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2010-12-28: NeonMice™

   NeonMice™ are the world's first commercially available Fluorescent mice.  They are genetically modified 'glow-in-the-dark' mice.  When viewed under a standard UV black light, NeonMice™ emit green, red, blue, or yellow light.

2010-12-26: Zeus – The Deermouse

Diary of Angie’s Deermouse




2010-12-21: Cattanach’s translocation is not the cause of Splashed and Tricolour


Cattanach's translocation involves the transposition of material* from an autosome into a X chromosome, so that this X* becomes the longest chromosome in the complement.

X-inactivation (also called lyonization) is a process by which one of the two copies of the X chromosomes present in females is inactivated. The inactive X chromosome is silenced by packaging into transcriptionally inactive heterochromatine. X-inactivation occurs so that the female, with two X chromosomes, does not have twice as many X chromosome geneproducts as a male, which only possess a single copy of the X chromosome. The choice of which X chromosome will be inactivated is random in mice and other mammals (including humans), but once an X chromosome is inactivated it will remain inactive throughout the lifetime of the cell and its descendants in the organism.

The coloration of tortoiseshell cats is a visible manifestation of X-inactivation. The black and orange alleles of a fur coloration gene reside on the X chromosome. For any given patch of fur, the inactivation of an X chromosome that carries one gene results in the fur color of the other, active gene.


Cattanach's insertions which include the normal C-allele translocated to the X-chromsosome is subject lyonisation too, so that XXC / cc mice have albino and pigmented patches. This is well known since the early sixties, see this publication for example: http://dev.biologists.org/content/96/1/295.full.pdf .

Therefore some fanciers thought Cattanach’s translocation is the molecular genetic background of Splashed and Tricolour mice. Unfortunately this can not be true, because Splashed (Spl) has a autosomal genetics and no gonosomal genetics. A splashed buck of course has one X chromosome only. If Spl would be located on the Cattanach’s translocation, the X-chromosome, he could give birth to splashed daughters only, but never to splashed sons, if crossed to a non-splashed female: XC/Y ce/ce crossed with X/X ce/ce would give non-splashed sons only (XY ce/ce) and 100% splashed daughters (XCX ce/ce).


We all know that this does not happen. Fazit: Unfortunately the molecular basis of Spl still remains unknown.

2010-12-15: Deermice - The Gang

2010-12-12: This is a new couple Black Tan Merle. Both carry piebald. The size of Merle in my stud is slowly improving, the type and ears still need a lot of work.

2010-12-10: Viable Female and Male Mice from Two Fathers Produced


Using stem cell technology, reproductive scientists at the M.D. Anderson Cancer Center have produced male and female mice from two fathers. Lead researcher Richard R. Behringer said the knowledge gained could help in preserving endangered species and improving livestock breeds, as well as opening up the possibility of same-sex couples having their own genetic children.

In the journal Biology of Reproduction, Behringer explains how his team manipulated fibroblasts from a male (XY) mouse fetus to produce an induced pluripotent stem (iPS) cell line. About one percent of iPS cell colonies grown from this XY cell line spontaneously lost the Y chromosome, resulting in XO cells. The XO iPS cells were injected into blastocysts from donor female mice. The treated blastocysts were transplanted into surrogate mothers, which gave birth to female XO/XX chimeras having one X chromosome from the original male mouse fibroblast.

The female chimeras, carrying oocytes derived from the XO cells, were mated with normal male mice. Some of the offspring were male and female mice that had genetic contributions from two fathers.

According to the authors, "Our study exploits iPS cell technologies to combine the alleles from two males to generate male and female progeny, i.e. a new form of mammalian reproduction."

The technique described in this study could be applied to agriculturally important animal species to combine desirable genetic traits from two males without having to outcross to females with diverse traits.

"It is also possible that one male could produce both oocytes and sperm for self-fertilization to generate male and female progeny," the scientists point out. Such a technique could be valuable for preserving species when no females remain.

In the future, it may also be possible to generate human oocytes from male iPS cells in vitro. Used in conjunction with in vitro fertilization, this would eliminate the need for female XO/XX chimeras, although a surrogate mother would still be needed to carry the two-father pregnancy to term.

Using a variation of the iPS technique, the researchers say "it may also be possible to generate sperm from a female donor and produce viable male and female progeny with two mothers."


Source: Deng et al. Generation of Viable Male and Female Mice from Two Fathers. Biology of Reproduction, Dec 8, 2010



2010-12-07: The day of birth and the biological clock

The season in which babies are born can have a dramatic and persistent effect on how their biological clocks function.


That is the conclusion of a new study published online on Dec. 5  by Ciarleglio et al, Nature Neuroscience, 2010. The experiment provides the first evidence for seasonal imprinting of biological clocks in mammals. The imprinting effect, which was found in baby mice, may help explain the fact that people born in winter months have a higher risk of a number of neurological disorders including seasonal affective disorder (winter depression), bipolar depression and schizophrenia.

In the experiment, groups of mouse pups were raised from birth to weaning in artificial winter or summer light cycles. After they were weaned, they were maintained in either the same cycle or the opposite cycle for 28 days. Once they were mature, the mice were placed in constant darkness and their activity patterns were observed.

The winter-born mice showed a consistent slowing of their daily activity period, regardless of whether they had been maintained on a winter light cycle, or had been shifted to summer cycle after weaning. When the scientists examined the master biological clocks in the mouse brains, using a gene that makes the clock cells glow green when active, they found a similar pattern: slowing of the gene clocks in winter-born mice compared to those born on a summer light cycle.

"What is particularly striking about our results is the fact that the imprinting affects both the animal's behavior and the cycling of the neurons in the master biological clock in their brains," said Ciarleglio.

In addition, their experiments found that the imprinting of clock gene activity near birth had dramatic effects on the reaction of the biological clock to changes in season later in life. The biological clocks and behavior of summer-born mice remain stable and aligned with the time of dusk while that of the winter-born mice varied widely when they were placed in a summer light cycle.

"The mice raised in the winter cycle show an exaggerated response to a change in season that is strikingly similar to that of human patients suffering from seasonal affective disorder," McMahon commented.

The new study raises an intriguing but highly speculative possibility: seasonal variations in the day/night cycle that individuals experience as their brains are developing may affect their personality.

(Remark Roland Fischer: A typical artificial summer has 16 hours of light and 8 hours darkness, a winter cycle has 8 hours of light)

"We know that the biological clock regulates mood in humans. If an imprinting mechanism similar to the one that we found in mice operates in humans, then it could not only have an effect on a number of behavioral disorders but also have a more general effect on personality," said McMahon.

"It's important to emphasize that, even though this sounds a bit like astrology, it is not: it's seasonal biology!" McMahon added.

Read the background and full story here:




2010-12-06: Why do mice get larger and larger during the decades of breeding for showtype?


The phenomenon, that humans grow to a higher bodysize from generation to generation, is often called acceleration: The mean body size increased from the last century to now.

Recently an interesting study about the genetics of human body size has been published in “Nature”. The genome-wide association (GWA) study of more than 180,000 individuals has identified hundreds of genetic variants in at least 180 loci associated with adult human height. The loci are not clustered randomly but are enriched for genes involved in growth-related processes that influence adult height (Allen et al., Nature, 2010: http://www.nature.com/nature/journal/v467/n7317/full/nature09410.html ). The growth hormon level is not the only factor involved.

Several studies have shown, that bigger persons are favored by several mechanism. One of these factors, but not the only, is the fact, that bigger people have a better chance to find a partner. This selection selects for persons with many loci coding for big bodysize and length.

Nevertheless the intake of food is an important factor too. A lot of essential aminoacids (animal protein) and vitamins are needed to realise the phenotypic potential , which is encoded by the genotype. Therefore humans in industrial areas and peaceful times grow to a higher size than individuals living in wartimes and poor countries.


The same system seems to be true for showtype mice. Bigger mice are selected for breeding, enriching the studs with mice carrying many loci coding for size. In addition the amount of animal proteins in food is high and reducing littersize allows the remaining weanlings to grow under best conditions.

2010-12-04: This buck is a carrier for piebald and will be my new stud buck for breeding broken merle. He was not bred to be a good black, he was bred to be a big black piebald carrier for improving the type of broken merle.



Anne is pregnant now:

Spl/* has an influence on p/p without c-dilutions, but only for the first 4 weeks. The adults do not show Splashed anymore. Here are pictures of three Spl/* p/p babies and her Spl/* p/p sa/sa mother and her little splashed brother:

2010-11-17: Finally we did it: 13 Mice from Chilloutarea Mousery are in Russia now...

...and they are in the hands of an enthusiastic and well educated veterinarian. Elena worked hard against many difficulties, but she was tough enough to realise  it. I love people who know what they want, and just do it! Congratulations, Elena!

This was not the last time of collaboration! Click the pic.

2010-11-14: Some Tricolors playing in the dirt and getting dirty:

2010-11-12: Chilloutarea Mousery is different !

2010-11-05: I found a  video with a pregnant Chilloutarea Tricolor in the www (click the pic):

2010-10-31: Today a Chilloutarea Mouse has won BIS2 in Sweden.

Congratulations to the new owner 'Lottiz' for treating the mouse so well that she could win!


New pictures of Deermice added, click here:

I got several deermice from a different line. The animals are from a research laboratory and some animal rescue people organized the transfer. The lab guys do not want to kill the animals which are not needed for experiments, they are happy if they find a home as pets. Nice people.
I got 8 of them, but not 8 females as they told us, there was 1 buck and 7 females in the group. Well, I’m a breeder, so I do not care...
These deermice are used to live in tiny macrolon boxes and got water and pellets only. The first hour they were unable to run straight forward, they moved in small circles and made saltos backwards.
Now they are the happiest deermice the world has seen. Life can be so exciting if you have been a lab mouse  all of your life and get free! They experience the taste of leafes, vegetables and seeds, and they have a lot of fun in their new box. They notice that they do not need to run in circles and that they can climb. Wow, life is beautiful!
I am sure, these mice think that they are in mouse heaven now.
Welcome in the  Chilloutarea Mousery!

Homo musculus: Researchers Create a "Humanized" Mouse for Liver Disease Studies


Long-awaited breakthroughs in developing preclinical animal models are signaling a new era


Chronic infection with malaria and hepatitis B and C occurring in more than 800 million people worldwide leads to at least 1.5 million deaths yearly. Although significant strides have been made in treatment and vaccination for these liver-based diseases, shortfalls remain. Progress has been stymied for several reasons, chief among them is the lack of an effective research model. Now, advances in mouse model creation are conspiring to usher in a new era in the research and treatment of these life-threatening maladies, and possibly many others.

Scientists studying these diseases have sought a research animal with both human liver cells and a human immune system. But this raises a conundrum: Engineering mice with human liver cells requires annihilation of the mouse immune system so that the foreign cells are not rejected, but the detrimental effects of both hepatitis B and C (HBV and HCV)—cirrhosis, scarring and even liver cancer stem from the immune response against the virus. Without an intact immune system, studying how viruses work and the potency of new therapies and vaccines is greatly hindered; new drugs can be explored, but the vital role that the immune system plays in enhancing efficacy will be lost. With chimpanzee research prohibited by ethical and financial concerns, and cell cultures providing an imperfect match to in vivo disease, the need for a way to devise a research mouse with humanized liver and immune cells has been clear.

Researchers at the Salk Institute for Biological Studies recently succeeded in overcoming two hurdles for a "humanized" model: engineering mice with livers housing enough human cells to properly study HBV and HCV, and creating enough of the animals. In addition to being immune-deficient, the mice also carried a genetic defect that leads to production of a liver toxin. From birth, the animals were given a drug to suppress the toxin, which was then slowly withdrawn, obliterating the mice's liver cells and leaving a space for human liver cells to engraft and expand within the architecture of the mice's livers. The approach led to mice with consistently high amounts of human liver cells. The animals also proved hardier than previous models, indicating that a population large enough to provide meaningful data could be obtained. The mice were susceptible to both HBV and HCV, and viral antigens present in the liver signaled that a humanlike process was at play.


Source: www.scientificamerican.com Jessica Wapner 2010-10-21

Tricolors from Chilloutarea Mousery in France:




2010-10-26:  Mother of 21:

This is one of my Tricolor does at the day before giving birth to her third litter. She is a very tame mouse and a good mother, but she is 10 months old now and this will be her last litter. The number of babies was 21...

2010-10-24: Deermice in Chilloutarea Mousery. New page added:

2010-10-22: Inbreeding - Line Breeding -Outcrossing

What is Inbreeding and what is it usefull  for?

What is Inbreeding Depression ?

How could the laboratory inbred mouse strains develop nevertheless?

What is hybrid vigour (Heterosis effect) ?

What is Outcrossing  ?

What is Line breeding ?

What has to be done if you want to use line breeding for your mousery ?

What should be done, if you have any questions ?


The full text is available as a pdf download here:


2010-10-21: Alien Anne - an update

Anne is a new mutation, but we do not know if it is a somatic mutation which will never breed true, or a germline mutation, which could be the  start of something great: If black dots on red fur breed true, this could be the start of a true Calico mouse with white & red & black, when combined with piebald. I will put her together with a buck in December. The fotos shows her brother too.
The chance to have a germline mutation is very low, but keep your fingers crossed, please.


2010-10-12: Rapid chromosomal evolution in island mice

Madeira is a small volcanic island in the Atlantic Ocean with steep mountains separating narrow valleys that are the only areas habitable by humans and their commensals. The extreme topography of Madeira has restricted the movement of mouse populations between valleys, setting the stage for extensive chromosomal radiation.

The authors of an interesting publication in “Nature” found six distinct chromosomal races of the house mouse on Madeira, separated from each other by mountain barriers.

The races have severely reduced diploid Chromosome numbers relative to the standard for the species (2n=40) owing to the presence of numerous robertsonian chromosomal fusions, each of which results from the joining of a pair of the standard chromosomes.

A Robertsonian translocation is a type of  nonreciprocal involving two chromosomes. A feature of chromosomes that are commonly found to undergo such translocations is that they possess an acrocentric centromere, partitioning the chromosome into a large arm containing the vast majority of genes, and a short arm with a much smaller proportion of genetic content. During a Robertsonian translocation, the participating chromosomes break at their centromeres and the long arms fuse to form a single chromosome with a single centromere. The short arms also join to form a reciprocal product, which typically contains nonessential genes and is usually lost within a few cell divisions.

These fusions have heen recorded in wild house mice, but the six races on Madeira that carry robertsonian fusions differ from each other and from races elsewhere as a result of the particular combinations of fusions that characterize them.

House mice are thought to have been introduced onto Madeira following the first Portuguese settlement during the fifteenth century, althongh fourteenth-century charts indicate that the island was known about before then. The extent of their chromosomal differentiation indicates that populations of house mice were isolated in different valleys for long enough to allow fusions to accumulate.

So far, not a single hybrid has been recorded between races carrying robertsonian fusions among the 143 mice that have been karyotyped.

Hybrids between any of the Madeirar mouse races carrying robertsonian fusions would be sterile or infertile owing to the complex chromosomal configurations that would be produced at meiosis.


Source: Janice Britton-Davidian et al., Rapid chromosomal evolution in island mice, Nature, Vol 403, 2000.

What is the impact of these findings for the mouse fancier? At least many more questions about what we know about our mice and what is still unknown. For the author of this homepage it remains unclear, how the races of Madeira have developed. Since hybrids between any of the Madeirar mouse races carrying robertsonian fusions and any of the original diploid 2n=40 wildtype would be sterile, at least one buck and one doe has to be born with the same chromosomal change at the same time and at the same place.

Is it god, who plays the game of evolution this way?

2010-10-06: Heimvorteil – Home Game Advantage

Auf heimischem Terrain kämpft es sich besser, aber warum?

Forscher haben in den Gehirnen von Mäusen jetzt eine Antwort gefunden: Das Gewinnen daheim verstärkt aggressives Verhalten - und macht auch auf dem Terrain des Gegners Lust auf weitere Raufereien.

Quelle: http://www.spiegel.de/wissenschaft/natur/0,1518,705041,00.html

Winning territorial disputes selectively enhances androgen sensitivity in neural pathways related to motivation and social aggression

Fuxjager et al.,  PNAS July 6, 2010 vol. 107 no. 27 12393-12398


Winning aggressive disputes can enhance future fighting ability and the desire to seek out additional contests. In some instances, these effects are long lasting and vary in response to the physical location of a fight. Thus, in principle, winning aggressive encounters may cause long-term and context-dependent changes to brain areas that control the output of antagonistic behavior or the motivation to fight (or both). We examined this issue in the territorial California mouse (Peromyscus californicus) because males of this species are more likely to win fights after accruing victories in their home territory but not after accruing victories in unfamiliar locations. Using immunocytochemistry and real-time quantitative PCR, we found that winning fights either at home or away increases the expression of androgen receptors (AR) in the medial anterior bed nucleus of the stria terminalis, a key brain area that controls social aggression. We also found that AR expression in brain regions that mediate motivation and reward, nucleus accumbens (NAcc) and ventral tegmental area (VTA), increases only in response to fights in the home territory. These effects of winning were likely exclusive to the neural androgenic system because they have no detectible impact on the expression of progestin receptors. Finally, we demonstrated that the observed changes in androgen sensitivity in the NAcc and VTA are positively associated with the ability to win aggressive contests. Thus, winning fights can change brain phenotype in a manner that likely promotes future victory and possibly primes neural circuits that motivate individuals to fight.

Source: http://www.pnas.org/content/107/27/12393.abstract


2010-09-29 The teeth of Satins


Sometimes it is not easy to tell from the appearance of the fur, if a black self mouse is Satin (sa/sa) or not. If you want to be sure, you should not examine the fur, but the teeth: Satins have white teeth as shown in the following pictures, while non-satins (Sa/Sa or Sa/sa) have typical cream/yellow teeth.

The pictures have been done by Monica Amadigi (the owner from www.redcarpetmaus.ch), a breeder of high quality show type mice in Switzerland.

Teeth of Blue Satin (sa/sa)

Teeth of Black Satin (sa/sa)

Teeth of a NON Satin (Sa/*)

2010-09-28: Black Tan Merle and Choco Tan Merle Satin Bucks

2010-09-26: Recessive Reds from Chilloutarea feel well in  Lottiz's stud in Sweden:

Three young Piebald Merle sisters. They have little k-factors, but this is how I want  pied Merle, because Merle Piebalds with  more k-factors are sometimes very light. The darkest one is the best, they should have equal amounts of black & grey & white.

2010-09-23: American Scientists have finally identified the stupidity gene RGS14


American scientists have discovered a gene in mice, deletion of which leads to the improvement of their mental faculties. This stupid gene, called the Homer Simpson gene on behalf of the protagonist of the popular cartoon series, was found also in humans. So American Scientist have finally identified the stupidity gene RGS14, but will we be able delete them at will?

According to recent publication of the National Academy of Sciences,experts from Emory University in the U.S. city of Atlanta (Georgia) during the experiment in laboratory mice have deleted the gene RGS14. This gene is associated with a particular area called CA2 of the hippocampus. This part of the brain is involved in consolidation of new knowledge and memory.

During the experiments, it was found that mice with gene RGS14 deleted are better at remembering different things that researchers have put them in a cage and quickly found a way out of the tangled maze, guided by the fixed in-memory pointers, rather than animals in which this gene was not deleted. Scientists have suggested that RGS14 limits the ability of the animals to remember and learn and therefore called it “the genome of Homer Simpson.”

The same gene was also found in humans. However, researchers are not sure that removing RGS14 can benefit both people and mice. “The question is, why do we, and mice have this Homer Simpson gene in the first place – a gene that makes the individual more stupid? – reflects one of the workers on the project scientists, John Hepler. – I think that we do not see the big picture entirely. RGS14 may be very important for the processes of learning and memory. In this case its removal may adversely affect the mental abilities.




2010-09-21: Drofi's Passiflora Tetraploids & Science:

(click the pic to download the paper)

2010-09-20: Pictures from Chilloutarea Mice living in Sweden now:

(click the pic for the link)

2010-09-14: Tricolors from Chilloutarea Mousery arrived

in France:(click the pictures for the links)

and here:


and Luxemburg  (Luxembourg) :


and Sweden: 

Enjoy your new mice!


2010-09-04: Today I finished the new headcount

and I am proud  to care for exactly 429 adult Mus musculus.

I know them all individually, they all are different individuals and personalities, and not a single one of them has to live in a lab cage. It is a good piece of work ( and a lot of fun!). We did not count the pygmies and other rodents.

2010-09-04: Mr. Charming, a true gentleman !

Mouse bred by Jack Garcia from Kentucky,  picture created by Zia from Georgia

2010-09-03: Happy people, happy mice:

2010-09-01: This is a true Chillout Area – not only for mice!


2010-08-26: The Plantsman Vol. 9 2010:
My tetraploid hybrids are the base for breeding hardy Passiflora in the UK. Click the pic for the download and start reading about my hybrids at page 272:

2010-08-20: Do you like camel spiders?


2010-08-19:   not guilty - informed !


Chilloutarea Mousery is the first european breeder of Tricolor with extensive experience and has adapted the first european Standard definition for Tricolors with the help of american friends. Feel free to Copy&Paste the text and example fotos of this standard for any purpose without restriction! Just cite me as the author please.

Download the Standard for Tricolor in German Language here:


Here are fotos of some new babies, which are from my programm to breed Broken Tan Satin Merle. One of the babies has markings, which come close to my goal: Broken black merle, who have 1/3 white, 1/3 grey and 1/3 black. It is typical for my recessive merle lines, that they show the merle markings very early in life.

2010-08-13: an update about Alien Anne

She is less sooty now and e/e for sure, but still shows her black markings. A strange and cute girly.

2010-08-01: The colours of recessive RED

Recessive Yellow (e/e) can Recessive Red, if you are willing to add more pheomelanine factors, eg by crossing with Golden Agoutis. Here are some examples from my stud:


1 is similar to the original US import mice

2 is from crossing no 1 with GA and selfing the resulting F1 agoutis (linebreeding, no inbreeding)

3 is from crossing no 2 with GA and selfing the resulting F1 agoutis (linebreeding, no inbreeding)

4 is from crossing no 1 with GA and selfing the resulting F1 agoutis (linebreeding, no inbreeding), but Tan (recessive Sable).

2010-07-31 ‘Alien Anne’ – who are you?

This little lady came up in a litter of agoutis carrying recessive yellow. The parents are A/* B/b E/e. There is no chance that the parents carry merle or splashed, and even if they did, this girly is not typical. I would be happy if she is a new mutation. So far she is doing well, although she is much smaller than her siblings. Perhaps she is just a poor girly having a Trisomy (triple chromosome) or a somatic mutation as shown here:

http://www.ashgi.org/color/Aussie_somatic_mutations.html ? Keep, your fingers crossed for having a new germcell mutation instead of a trisomy or a somatic mutation!

Anyway, I love ‘Alien Anne’ and will protect her for ever!


Chilloutarea Mousery in TV !

The Truth of the News:

The owner of Chilloutarea Mousery in the Television:

(Speakers on!  Full screen!)


2010-07-19: Golden Agouti, what is it and why should we breed it ?

GA is a version of Agouti, which has been selected in more than hundred years for pheomelanine factors. The siblings of GA have been Dominant Reds (Ay/*).

This colour is very helpfull for breeding red into different lines.

Here are some pics of 4 GA and their Cinnamon Cousin:

2010-07-16: Surprised Kitty


2010-07-12: Jenna Dewan Tatum & Peta


5 splashed CPB sisters, 6 weeks old.

They have the gene code a/ae ce/ch S/s Spl/spl. One of them is not as dark as the others.

2010-06-14: Extreme Nonagouti Black & Tans (ae/at)


Black-and-tan (at) mice have a black dorsum and yellow or cream belly. They have been first described by Dunn in 1928. Some yellow pigment is also found behind the ears of at mice. at is dominant over non-agouti. It is not possible to separate at/at from a/at by the phenotype, both homocygotous and heterocygotous Black & Tans just look black and tan. The allele at is particularly interesting because it is recessive to A on the dorsum, but dominant to A on the ventrum.


Extreme nonagouti ( ae) was found and described by Hollander & Gowen in 1956. It appeared after irradiation mutagenesis (J Hered.1956; 47: 221-224). The Jax homepage describes ae as recessive to all the other alleles of the agouti series. Homocygotous ae mice are completely eumelanotic. No yellow hairs occur on the ears or around the genitals.

Here are some pictures from Jax: http://www.informatics.jax.org/javawi2/servlet/WIFetch?page=alleleImages&key=12


No information is available about the phenotype of at/ae. Is there any interaction between at and ae? What is the phenotype of an Extreme Non-Agouti Black and Tan (ae/at)?


From my experiments to improve the colour of Merle, I crossed a nice nonagouti black and tan merle buck (a/at) to a normal non-agouti black (a/a) female and to an extreme nonagouti (ae/ae) female. The tan halfsiblings from both mothers differ very much:

The picture on the left shows a/at, while the right picture shows ae/at.

NOTE! These mice are no Black & Tan Showtype! They are a very small step to improve colour and type of Merle only!

Conclusion: Black & Tan (at) is dominant over ae, but there seems to be some interaction between ae and at on the phenotype of heterocygotous mice.



The genetics of Hereford mice


Little information is available in the web about the genetic background of Hereford mice. While mice with headspots normally are just piebalds (s/s) with little or no k-factors, the genetic basis of herefords seems to be an own distinct mutation.

Silvia Iseli from Switzerland breeds nice Herefords and has good knowledge about the variety, she found the following paper (click the pic):

The genetic background of Herefords seems to be the autosomal recessive mutation on chromosome 15, called “white nose” (wn).

Here is a picture of Silvia’s Hereford babies:

2010-05-26: Tricolors from Chilloutarea Mousery arrived in the Netherlands and got a very warm welcome:



Merle Babies


Some pics of a splashed Buck and his dove doe. I am waiting for a litter.


Chilloutarea Mice arrived in the USA.

They will be the start for American/European hybrids in the mousery of one of the best breeders in the United States.


Mouse Agility – World’s smartest mouse:


2010-04-18 NMC UK Spring Show

Mouse breeding has a long tradition in the United Kingdom and most (if not all) showtype mice have their roots on the British Island.

The NMC Spring Show was a nice chance for me to visit some of the very best UK breeders.

Many thanks to Heather, Samantha and Sarah for the warm welcome! It was a pleasure to meet you, and your mice are lovely! Thank you for the exciting and wonderful weekend! I will never forget  and your mice will be treated very well in my stud.
Congratulations to Heather for winning "Best of Show", and I really fell in love with Sarah's Doves. Sarah, your mice are amazing! You will have a great future as a leading breeder in the UK, I am sure!
Visitors of my homepage, please enjoy the  pics. They are a pale copy of my impressions at this wonderful weekend only. Reality was better.

The area around Hermitage is very nice!

... and relaxed: The local supermarket in Hermitage and the cemetery.

Mouse Show at Hermitage Village Hall. Breeders from all over the UK drive many miles to visit this lovely place and meet other mouse enthusiasts here.

Heather, Sam , Sarah

Me and Alan.
Together we have 134 years of experience in mouse breeding, but the ladies just have more feeling (and beauty). Heather, Sarah, Sam, thank you for the nice weekend!


Click the pic:


Ist es möglich Farbe und negativen Einfluss auf die Gesundheit in dominant roten Mäusen züchterisch zu trennen?


Die folgenden Publikationen belegen sehr deutlich die direkte und untrennbare Verknüpfung der gelben Haarfarbe und der Belastung durch Übergewicht, Diabetes und Tumoranfälligkeit  bei dominant gelben (roten) Mäusen.

Es ist unmöglich Farbe und schlechte Gesundheit bei Ay Mäusen züchterisch zu trennen, beides ist untrennbar miteinander verbunden.


It is impossible to separate colour and pronounced obesity, diabetes, and the development of neoplasms in dominant yellow (AY) mice.


Obesity, diabetes, and neoplasia in yellow AVY mice: ectopic expression of the agouti gene.

The viable yellow AY mutation results in a mottled yellow mouse that is obese, slightly larger than its nonyellow sibs, and more susceptible to tumor formation in those tissues sensitized by the strain genome. The mutation exhibits variable expressivity resulting in a continuum of coat color phenotypes, from clear yellow to pseudoagouti. The mouse agouti protein is a paracrine signaling molecule that induces hair follicle melanocytes to switch from the synthesis of black pigment to yellow pigment. Molecular cloning studies indicate that the obesity and growth effects of the A mutation result from ectopic expression of the normal agouti gene product. This review seeks to summarize the current state of knowledge regarding the obesity, stimulation of somatic growth, and enhancement of tumor formation caused by the AVY mutation, and to interpret these pleiotropic effects in terms of the normal function of the agouti protein.

Yen, T. et al., FASEBJ. 8: 479-488; 1994.

Sources: http://www.fasebj.org/cgi/reprint/8/8/479 (free Fulltext)

Mittenberger et al., The Role of the agouti Gene in the Yellow Obese Syndrome, J. Nutr. 127: 1902S–1907S, 1997 http://jn.nutrition.org/cgi/reprint/127/9/1902S (free Fulltext)

BULTMANN, S.J.; MICHAUD, E.J.; WOYCHIK, R.P.: Molecular characterization of the mouse agouti locus. Cell,71,1195-1204,1992: “...we found that the pleiotropic effects associated with the lethal yellow (Ay) mutation, which include pronounced obesity, diabetes, and the development of neoplasms, are accompanied by deregulated overexpression of the agouti gene in numerous tissues of the adult animal.”

MOUSSA, N.M.; CLAYCOMBE, K.J.: The yellow mouse obesity syndrome and mechanisms of agouti-induced obesity. Obesity research,7(5),506-514,1999: “This syndrome is caused by ectopic expression of Agouti in multiple tissues.”


Besteht eine Verbindung zwischen Farbe und Körpergröße bei Mäusen?

Is there an influence of certain colour alleles on body size?

In verschiedenen Publikation wird der Zusammenhang zwischen Größe und Farbmutationen bei Farbmäusen beschrieben. Bei heutigen Showtype Mäusen sind oft die Albinos sehr groß und typvoll. Es besteht jedoch kein Zusammenhang mit dem c-Allel, wie oft angenommen wird. Sehr wahrscheinlich war nur die einfachere Selektion dafür verantwortlich, da die Züchter nur auf den Typ und nicht auf Farbfehler achten mussten. Ein direkter Zusammenhang besteht dagegen bei Mäusen in chocolate (b/b).


CASTLE, W.E.: Influence of certain color mutations on body size in mice, rats and rabbits. Genetics,26,177-191,1941

This paper is a further contribution to a series of studies on size inheritance in mice begun some years ago at the Bussey Institution of Harvard University by my colleagues and myself and designed to throw light on the question how particular mutant genes affect the growth of the body and so influence adult body size.

In previous studies it was found that the gene for brown pigmentation and the gene for dilute pigmentation accelerate growth and thus increase adult body size, as judged by criteria of body weight, body length, and tail length. By like criteria it has been found that the gene for short-ear and the gene for pink-eye decrease adult body size, but that the gene for agouti and the gene for complete albinism are neutral, neither increasing nor decreasing body size.

The present study is concerned with the influence on body size of three other mutant genes, leaden, pink-eye 2, and yellow. Leaden is phenotypically similar to blue dilution, and pink-eye 2 is phenotypically similar to ordinary pink-eye, but both are entirely distinct genetically from the better known mutants which they resemble. Leaden, unlike blue dilution, has a retarding influence on growth, and pink-eye 2 has a stronger retarding effect than ordinary pink-eye, as will presently appear. Yellow, as is well known, has a lethal effect when homozygous but increases body size when heterozygous. This paper deals also with a further study of the influence of the brown mutation on body size, the investigation being extended from mice to rats and rabbits also.

In all crosses studied brown mice are larger than their dominant black sibs. The evidence from coupling and repulsion experiments along with the fact that all strains of brown mice so far tested have shown association between the brown gene and larger body size, suggests that the brown gene itself is influencing general body growth.

Piebald mice are smaller than their unspotted sibs for all characters

except tail length in males.

Breeders of albinos or other pale colours do not need to take care of colour mistakes and can focus on type. Therefore mice with these colours often have larger bodies after geerations of selection, allthough the colour alleles of these colours do not contribute to the larger size directly.

Sources: http://www.genetics.org/cgi/reprint/26/2/177 (free Fulltext) and

LAW, L. W., 1938, Studies on size inheritance in mice. Genetics 23: 399-422.


Melanogenesis, the molecular basis of fur colour in mice


The different fur colours in mice are caused by the regulation of pigments and their distribution in melanocytes. Mice and most other mammals have two types of pigments, the black or dark brown eumelanin and the yellow or reddish pheomelanin.

The cordination of switching between the synthesis of eumelanin or pheomelanin is controlled by several genes in the melanocytes.

The colour of the individual hairs is the basis for the colour of the fur in mice and is determined by the density of melanintypes and the distribution melanin types.

Typical wild-type (agouti) hairs in mice have a subterminal band of light-colored pheomelanin flanked by dark eumelanin, giving an overall brushed appearance.

Mutations in these genes for this pathway alter the overall coat colour of our mice.


New fotos of Eurasian Pygmy Mice added. Click the pic:

There are several texts in the www about this species and they write the groups would be dominated by a female and females would be aggressive against each other. From my experience this is not true at all. Females live in harmony very well, but two bucks fight each other to death.

Fathers even kill their own boys, when the boys are some weeks old. I have to separate the boys from their father early enough and have to separate them from each other some weeks later, when I see the start of disharmony. This species shows the strongest aggressive behaviour between males compared to all mouse species I have ever owned.

My conclusion: Micromys minutus shows no difference in this aspect to other mouse species, males do not live in harmony. Probably one author was wrong a long time ago and the others just copied him again and again.


Hautpilze bei Mäusen sollte man ernst nehmen!

Dealing with Ringworm in Mice

by Jack García with help from Amanda Mullins, B.Sc.(Agr.)



New fotos added to "Tricolors" (click the pic):

New fotos added to "Other Colours" (click the pic):


This song (click the pic) is dedicated to a very special person, she is a very typey Recessive Red :-)

oh oh oh oh oh yeeeeaaaaah!


Was sind Knockout Mäuse?

Es handelt sich um genveränderte Mäuse, die inzwischen in vielen Forschungsbereichen von grundlegender Bedeutung sind.

Mehr als 10.000 Gene, etwa die Hälfte aller Säugetier-Gene, wurden bereits mittels Gen-Targeting verändert, und weitere Gene werden folgen, denn technisch ist es möglich, jede beliebige Veränderung in der DNA von Mäusen vorzunehmen, um auf diese Weise die Rolle der Gene für die normale Physiologie oder für Erkrankungen zu erforschen.

Quelle: http://www.aerzteblatt.de/v4/news/news.asp?id=30065




What are knockout mice?

Mus musculus is an excellent model for human diseases because the organisation and expression of their genes is very similar to humans. If the mouse genes are manipulated another disease can develope that does not normally affect them. Studying these mice helps to understand human physiology and diseases.


What are transgenic mice?

Altering chromosomes of mice so that its genes contain foreign DNA forms transgenic mice. The foreign DNA can come from any source of DNA, eg humans.


How are  transgenic mice made?

DNA introduced into embryonic stems cells usually integrates randomly into the genome. If the new DNA has a similar sequence to an existing part of the sequence from the mouse it can be exchanged by homologous recombination. The result is that a single copy is integrated into the mouse DNA at a specific location. If these embryonic cells are injected into a host embryo, they will become a part of the adult mouse. The adult mouse still is a chimera, because it is formed from embryonic cells of two different individuals. Some of the sperm or eggcells produced by this chimeric mouse will contain the foreign DNA, and when these cells fertilise a normal germcell, the resulting offspring which grows from it is transgenic with the foreign DNA in each cell.


What are knockout mice?

A new technique allows to alter particular genes on the DNA. The particular genes can be removed, or inserted or inactivated. Since the complete mouse genome is seuquenced now, many genes can be targets of this technique now. It is possible to study the exact function of the particular gene. When a gene is missing or inactivated the researchers will see what function is lost in the mouse.

Therefore knockout mice are very good models for many human diseases, where no animal models were avaialable before. In 2007 Mario Capecchi, Martin Evans and Oliver Smithies were honored with the Nobel Prize in mecine for the creation of the first knockout mice.


How are  knock-out mice made?

The technique which allows to alter specific genes of the mouse is gene-targeting. A similar genetic sequence is used to replace the target gene. Often minor changes in the sequence prevent the gene from functioning. If the original dectivated mouse gene is replaced by a human gene, it is often possible to study the function of this particular human gene.

The similar gene sequence used to replace the original mouse gene is produced by chemical synthesis and/or by amplification in bacterial plasmids. The DNA is harvested in larger amounts and then injected into mouse embryo stem cells from a very early mouse embryo. They have the potential to develope and divide to build up each type of cell in the body of the mouse. The injected DNA recombines with the natural genetic material and this brings the new mutant gene into the genome of the mouse embryo cells, which have to be implanted inot a normal mouse embryo. Normally th researchers use embrynic cells from white mice for the mutagenesis and ebryos from coloured mice as hosts fro these cells. When the mouse is grown to an adult it is easy to see from the colour of the fur which mouse has the mutant genes. These animal will develope sperm cells containing the mutant gene.

The mouse which is bornis a chimera from fur of both colours (white and dark), and only some of its cells will be modified.

When sperm from this chimera fertilises a normal eggcell, some of the babies will have the same colour as the mouse whose gene was altered. Inbreeding will result in offspring with two alleles of the mutant gene. These mice are knockout mice.

If you want to read more details, please have a look to the homepage of the Nobel Prize organisation:



Brauchen Mäuse Vitamin C?

Die meisten Tierarten können Vitamin C (Ascorbinsäure) selbst synthetisieren. Zu den Ausnahmen zählen u.a. der Mensch, Primaten, Meerschweinchen und obstfressende Fledermäuse, denen allesamt das Enzym L-Gulonolaktonoxydase fehlt. 

Für Mäuse und Ratten stellt Ascorbinsäure also kein Vitamin dar, sie sind nicht auf Zufuhr mit der Nahrung angewiesen.

Einen Überblick über die Besonderheiten der Nährstoffansprüche von Mäusen findet man hier:



Do mice need additional Vitamin C?

Inability to synthesize vitamin C (ascorbic acid) because of a deficiency in gulonolactone oxidase expression, is a genetic deficiency shared by a small number of animals including humans, primates, guinea pigs and bats. Mice do not need food with ascorbic acid, it is no vitamin for mice, because they express gulonolactone oxidase.

If you want to read a good overview about the nutient requirements of mice, have a look here:




Konventionelle Käfighaltung beeinträchtigt die Gehirnentwicklung und das Wohlergehen von Labormäusen

Verbesserungen durch Käfiganreicherung mittels Unterschlupf, Nestmaterial sowie Spiel- und Klettermöglichkeiten wären leicht realisierbar. Doch Tierexperimentatoren befürchten, dass komplexere Haltungsbedingungen die Standardisierung von Tierversuchen gefährden. Forscher der Universitäten Gießen und Zürich belegen nun, dass diese Befürchtungen haltlos sind: Daten von Mäusen aus angereicherten Käfigen waren ebenso präzis und reproduzierbar wie die von Mäusen aus konventioneller Käfighaltung. Einer Verbesserung der Haltungsbedingungen für Versuchstiere steht damit aus wissenschaftlicher Sicht nichts mehr im Wege. Davon könnten jährlich Millionen von Tieren weltweit profitieren.

Vermutungen, wonach komplexere Umweltbedingungen die Standardisierung von Tierversuchen gefährden, standen bisher Verbesserungen der Haltungsbedingungen von Versuchstieren im Wege. Diese Befürchtungen wogen doppelt: Eine größere Variabilität der Daten würde nicht nur die wissenschaftliche Aussagekraft von Tierversuchen gefährden, sondern würde aus statistischen Gründen zudem eine größere Anzahl von Versuchstieren pro Versuch erfordern. Unter der Leitung von Hanno Würbel, Professor für Tierschutz und Ethologie an der Universität Gießen, wurde diese Vermutung nun erstmals systematisch geprüft. In seinem Gießener Labor sowie in zwei Forschungslabors der Universität Zürich wurden Mäuse verschiedener Zuchtlinien in konventionellen und in angereicherten Käfigen aufgezogen und anschließend in vier gebräuchlichen Verhaltenstests untersucht. Die Befunde, die in der Fachzeitschrift Nature am 16. Dezember 2004 publiziert werden, sind eindeutig: Durch die angereicherte und damit tiergerechtere Haltung wurde weder die Variabilität der Versuchsergebnisse, noch deren Vergleichbarkeit zwischen unabhängigen Versuchswiederholungen in den drei Labors beeinträchtigt. Zudem verhielten sich die angereichert aufgezogenen Mäuse in allen Tests wesentlich weniger ängstlich. Somit steht einer Verbesserung der Haltungsbedingungen für Labormäuse auch aus wissenschaftlicher Sicht nichts mehr im Wege.

Quelle: http://www.innovations-report.de/html/berichte/studien/bericht-37900.html

Laboratory animal welfare: Cage enrichment and mouse behaviour

Mice housed in standard cages show impaired brain development, abnormal repetitive behaviours (stereotypies) and an anxious behavioural profile, all of which can be lessened by making the cage environment more stimulating. But concerns have been raised that enriched housing might disrupt standardization and so affect the precision and reproducibility of behavioural-test results. The authors show that environmental enrichment increases neither individual variability in behavioural tests nor the risk of obtaining conflicting data in replicate studies. Their findings indicate that the housing conditions of laboratory mice can be markedly improved without affecting the standardization of results.

Source: Wolfer et al., Nature 432, 821-822, 2004


Tiergerechte Haltung von Labormäusen.

Das umfangreiche  Heft der Gesellschaft für Versuchstierkundehttp://www.gv-solas.de/auss/hal/maushaltung.pdf


APPENDIX A to the European Convention for the Protection of Vertebrate Animals used for Experimental and other Scientific Purposes. Guidelines for accomodation and care of animals).



Dollar Bill in Mouse Pictures


The reason the mouse fancy (and a few other small animal fancies) uses the bill in pictures with mice is because it is uniform in size and shape and gives a good reference point. The American bill is readily available in most countries where mice are fancied, and has become a universal reference point.

Mice can't control their poop so that's why there is poop on the pictures sometimes. It's a consequence, not a major point. We have the utmost respect  for the American dollar.

The US East Coast Mouse Association (eastcoastmice.org) uses the dollar bill in all its online shows as a universal size and color reference.



Today a nice lady sent this postcard to me.

I like it, but I do not agree, I am not shy...


Kuschelnde Männchen und balzende Weibchen -

Neue Forschergruppe untersucht vorgeburtlich erworbene Eigenschaften: Fehlverhalten oder Anpassung?


Männlich oder weiblich? Bei einem Meerschweinchen ist das nicht auf den ersten Blick erkennbar. Es sei denn, es balzt. Dann ist es ein Männchen - meistens. Es kann aber auch ein Weibchen sein, dessen Mutter während der Schwangerschaft sozialem Stress ausgesetzt war. Dann haben die Töchter körperliche Besonderheiten wie einen erhöhten Spiegel "männlicher" Hormone im Blut und zeigen Balzverhalten. "Vorgeburtlicher Stress kann bei Meerschweinchen und anderen Tieren ebenso wie beim Menschen die Entwicklung beeinflussen", sagt der Verhaltensbiologe Prof. Dr. Norbert Sachser von der Westfälischen Wilhelms-Universität Münster (WWU). "Bislang ging man davon aus, dass solche Verhaltensänderungen Abweichungen von der Norm darstellen oder gar krankhaft sind. Wir fragen uns nun: Können sie auch eine Anpassung an die Umwelt sein?" Eine Antwort darauf wollen die Wissenschaftler durch ein neues Forschungsprojekt finden.

Das Team vom Institut für Neuro- und Verhaltensbiologie um Norbert Sachser und Privatdozentin Dr. Sylvia Kaiser ist Teil einer überregionalen Forschergruppe, die von der Deutschen Forschungsgemeinschaft (DFG) neu eingerichtet wurde. Die Wissenschaftler vermuten: Neben der evolutionären Anpassung durch Selektion über die Generationen gibt es auch kurzfristige Verhaltensanpassungen. Diese werden beispielsweise durch die Lebensumstände der Mutter während der Schwangerschaft festgelegt und sind nicht genetisch bestimmt.

"In stabilen kleineren Meerschweinchengruppen bekommen Weibchen, die sich 'typisch weiblich' verhalten, mehr Nachwuchs", vermutet Sylvia Kaiser. "Dagegen könnten in sehr großen Gruppen, in denen die Sozialpartner häufig wechseln, die durchsetzungsstärkeren 'vermännlichten' Weibchen einen Vorteil haben und sich besser fortpflanzen." Norbert Sachser ergänzt: "In der Natur schwankt die Populationsdichte von Wildmeerschweinchen stark. Wir vermuten, dass eine Meerschweinchenmutter, die während der Schwangerschaft in einer großen, instabilen Gruppe lebt, ihre Töchter auf genau diese Lebensbedingungen optimal vorbereitet. Die Vermännlichung wäre dann eine Anpassung, kein Fehlverhalten."

Auch die Söhne von "gestressten" Müttern verhalten sich anders als ihre Artgenossen. "Während andere Meerschweinchen mit der Pubertät Balzverhalten und Dominanzgebaren an den Tag legen, um möglichst viele Weibchen für sich zu gewinnen, haben diese Männchen eine verzögerte Entwicklung. Sie kuscheln gern und verhalten sich, als wären sie noch nicht geschlechtsreif", so Norbert Sachser. Was klingt, als könnten die Tiere mit den "richtigen Männern" in der Gruppe nicht mithalten, könnte sich als Vorteil entpuppen - zumindest solange sie wie ihre Mütter in einer großen Gruppe mit vielen dominanten älteren Männchen leben. Denn die jungen Männchen warten, bis ihre Chance gekommen ist. Erst wenn sie körperlich in der Lage sind, mit den "Platzhirschen" um die Weibchen zu konkurrieren, zeigen sie Werbeverhalten. Vorher vermeiden sie aussichtslose Auseinandersetzungen.

Neben der Phase vor der Geburt interessieren sich die münsterschen Forscher noch für einen anderen sensiblen Zeitraum: die Pubertät. "Hier wird noch einmal 'nachjustiert'. Die Tiere entwickeln in dieser Phase ein Verhalten, das angesichts der gegebenen Umstände einen maximalen Fortpflanzungserfolg garantiert", vermutet Norbert Sachser. Gemeinsam mit Wissenschaftlern in Potsdam und Bielefeld, von wo aus das Projekt koordiniert wird, wollen die Münsteraner ihre Hypothesen nun überprüfen. Dazu untersucht die Forschergruppe nicht nur Meerschweinchen, sondern auch Wühlmäuse, Zebrafinken, Blattkäfer und Wachsmotten. Die DFG unterstützt das Projekt für zunächst drei Jahre mit 1,5 Millionen Euro. Rund 450.000 Euro gehen an die münsterschen Forscher, welche auch die Hormonuntersuchungen für alle beteiligten Wissenschaftler durchführen.


Quelle: Universität Münster 17.2.2010


Effects of Prenatal Social Stress on Offspring Development: Pathology or Adaptation?


Kaiser & Sachser, Current Directions in Psychological Science, Volume 18, Number 2, April 2009 , pp. 118-121(4)


In nonhuman mammals, the social environment in which pregnant females live is critical for their offsprings' brain development, endocrine state, and social and sexual behavior later in life. Social instability during pregnancy generally brings about a behavioral and neuroendocrine masculinization in daughters and a less pronounced expression of male-typical traits in sons. We favor the hypothesis that such behavioral effects of prenatal social stress are not necessarily “pathological” (nonadaptive) consequences of adverse social conditions. Rather, pregnant mothers could be adjusting their offspring to their environment in an adaptive way.


Source: http://www.ingentaconnect.com/content/bpl/cdir/2009/00000018/00000002/art00011

Musical Greetings:
This songtext very well reflects what I have learned in life and what I try to live. Be well!



Kuhpocken bei Haltern von zahmen Farbratten

Cowpox Virus Infection in Pet Rat Owners—Not Always Immediately Recognized


The aim of this article is to make pet owners and physicians of all specialties aware of the possible variations of clinical course in human cowpox infection. This has been a matter of current interest since the detection of a first cluster of infections among owners of white pet rats in the Krefeld area in the spring of 2008. Two further cases arose in the Krefeld area in November 2008, and there have since been multiple further reports from various regions in Germany and the neighboring countries.


Englisch: http://www.aerzteblatt.de/int/article.asp?id=64638

German: http://edoc.rki.de/oa/articles/reCiWOPzE5Ew/PDF/23u4n8APNz7o6.pdf



Impressions from the Championshow Utrecht NL


What is bluer than blue?

Some thoughts about Dilute and Leaden


There are two mutations in Mus musculus which are phenotypically very similar: Leaden (ln, chromosome 1) and Dilute (d, chromosome 9). Both are recessive mutations and have a dilution effect on the colour when introduced into genotypes which otherwise provide for intensely pigmented hairs. The mice are called “blue” in the fancier community , although “grey” would be a better description than “blue”, but the wording “blue” is very common and well established for grey individuals of different species, eg grey pigeons (Columba livia) which are called “blue” too.


Is it possible to identify the genotype (ln/ln or d/d) from the look of the phenotype?

It is very difficult if not impossible to determine the genotype from the phenotype, because the phenotypes of ln/ln and d/d are very similar. Other genetic factors of the individual mouse can have an influence on the intensity of the colour, therefore two d/d mice can be different from each other. The same is true for ln/ln mice, which can be different to each other, and the differences can be stronger than the difference between ln/ln and d/d of otherwise similar mice, depending on the line and other genetic factors.


Does the combination of ln/ln and d/d have an effect on the phenotype?

No, when the d/d and ln/ln occur together, the mice are not different to mice which carry only one of these mutations.


What colour does the offspring have, when we cross d/d with ln/ln?

It is very surprising for breeders, when they breed two blue mice together and get a litter of 100% black mice. Both mutations ln and d are located on different chromosomes and recessive. Therefore the offspring is black, because the genotype is D/d Ln/ln. To be phenotypically blue, both alleles have to be mutated, not wildtype.


Do ln and d influence other colours differently?

Yes, leaden lilacs are a little lighter than dilute lilacs. The difference is very small. Leaden has less effect on the brightness of tan bellies than Dilute. Therefore Leaden Tans often have a better look than Dilute Tans.


What can a breeder do to find out, if his blue line is ln/ln or d/d?

Leaden, but not Dilute is epistatic to Recessive Yellow. Test matings of blue with Recessive Yellow will show what kind of blue it is. Recessive Yellow Leaden (e/e ln/ln) show no difference to Recessive Yellow Black (E/E ln/ln), while Recessive Yellow Dilute(e/e d/d) are lighter than Recessive Yellow Black.


The introductory question was, what is “bluer than blue”? Satin has a very nice and strong effect on Leaden and Dilute as well. The combination with satin gives grey mice, which are a little bit closer to the word “blue”.


The Ideal Mouse, by Jack García


Many people are curious about what makes up an "ideal mouse”.

Below is a drawing that will perhaps help people get a better understanding of what the standards actually mean.



HEAD- The head should be long, clean and wedge-shaped. It should not be too wide or too narrow but should have a rounded shape. The lines of the face should be soft and should taper to a clean, dry nose that is not too pointy or fine. The width of the muzzle should be in proportion to the width of the head and should not be pinched or narrow. Bucks will have broader cheeks than does."


TAIL- The tail should be free from kinks and bumps and as long as possible, at least the length of the mouse. It should come out of a well-defined rump and should have a long, thick set-on that leads into the tail. The base to be thick, tapering to a fine point."


The author of several pieces of the above text and the owner of the drawing is Jack Garcia from Kentucky, who allowed me to use the pic and make an excerpt of his text.

Thank you for the good work and thank you for the collaboration , Jack!

Longevity in the Rat

This article originally appeared in Pro-Rat-A, January/February 2009 (number 169). The electronic format contains an extended bibliography. While originally written for rat fanciers, the methods discussed here can easily be modified and applied to just about any domestically kept species.


Red Light:

"The poor vision of mice makes them unable to detect color and red light is often used to observe animals during the dark cycle."


Just use a red light-bulb as a single light source at night and you will be able to observe your mice and watch their natural behaviour, while they are unable to detect you and are not shy at all.


Amino-acid imbalance explains extension of lifespan by dietary restriction in Drosophila


Richard C. Grandison1,2, Matthew D. W. Piper1,2 & Linda Partridge1

  1. Institute of Healthy Ageing, Department of Genetics Evolution and Environment, University College London, Gower St, London WC1E 6BT, UK
  2. These authors contributed equally to this work.

Correspondence to: Linda Partridge1 Correspondence and requests for materials should be addressed to L.P. (Email: l.partridge@ucl.ac.uk).

Dietary restriction extends healthy lifespan in diverse organisms and reduces fecundity1, 2. It is widely assumed to induce adaptive reallocation of nutrients from reproduction to somatic maintenance, aiding survival of food shortages in nature3, 4, 5, 6. If this were the case, long life under dietary restriction and high fecundity under full feeding would be mutually exclusive, through competition for the same limiting nutrients. Here we report a test of this idea in which we identified the nutrients producing the responses of lifespan and fecundity to dietary restriction in Drosophila. Adding essential amino acids to the dietary restriction condition increased fecundity and decreased lifespan, similar to the effects of full feeding, with other nutrients having little or no effect. However, methionine alone was necessary and sufficient to increase fecundity as much as did full feeding, but without reducing lifespan. Reallocation of nutrients therefore does not explain the responses to dietary restriction. Lifespan was decreased by the addition of amino acids, with an interaction between methionine and other essential amino acids having a key role. Hence, an imbalance in dietary amino acids away from the ratio optimal for reproduction shortens lifespan during full feeding and limits fecundity during dietary restriction. Reduced activity of the insulin/insulin-like growth factor signalling pathway extends lifespan in diverse organisms7, and we find that it also protects against the shortening of lifespan with full feeding. In other organisms, including mammals, it may be possible to obtain the benefits to lifespan of dietary restriction without incurring a reduction in fecundity, through a suitable balance of nutrients in the diet.


2009-11-27 How do you do it, if you have to euthanize an ill mouse?

There is a discussion about this difficult topic here:


2009-11-06  Inbreeding, Linebreeding and Crossbreeding



Zur Vermeidung von Inzuchtdepression sollte auch bei einer notwendigen Rückkreuzung zur Etablierung rezessiver Mutationen der Inzuchtkoeffizient klein gehalten werden.

Wenn man blutsfremd auskreuzen möchte kann man auch bei rezessiven Mutationen auf Inzestverpaarungen verzichten, sondern nutzt auschließlich die Linienzucht.

Der wichtigste Unterschied der beiden Verfahren besteht ja in dem unterschiedlich großen Inzuchtkoeffizienten der erlaubten Verpaarungen. Beim Verfahren der Linienzucht beträgt der Inzuchtkoeffizient dann schon in der F2 nur 12,5% und wird bei jeder weiteren Generation immer geringer, gleichzeitig gibt es aber in jeder Generation ausreichend viele Tiere, die auch phenotypisch die zu festigende Mutation tragen.

Das Prinzip dieser Methode der Auskreuzung ist denkbar einfach. Man geht in der praktischen Anwendung so vor, dass man grundsätzlich bei allen Verpaarungen nur einen Inzuchtkoeffizienten von 12,5% oder 6,25% erhält. Auf diese Weise ist es in relativ wenigen Generationen möglich auch rezessive Farben von der Verwandtschaft der Originaltiere zu trennen.

Wenn man den Inzuchtkoeffizienten nicht genau berechnen will kann man sich als Anhaltspunkt folgendes merken:

Es dürfen keine Eltern-Kinderverpaarungen erfolgen und auch keine

Verpaarungen von Geschwistern. Andere Verwandschaftgrade dürfen verpaart werden, da sich z.B. bei der Verpaarung von Halbgeschwistern nur ein Inzuchtkoeffizient von 12,5% ergibt, bei Verpaarung von Cousin und Cousine gar nur noch 6,25%

Wenn man danach erneut mit nicht verwandeten Tieren kreuzt und das gleiche Prinzip wiederholt, dann kann man sehr schnell Tiere erhalten, deren Inzuchtgrad in Bezug auf das Ursprungstier extrem gering ist.




To avoid inbreeding depression it is necessary to avoid close inbreeding. How can we establish a new recessive trait without close inbreeding?

Linebreeding is the way, and paying attention to the inbreeding coefficient is the best way.

The coefficient of kinship is defined as the probability that the alleles at a particular locus chosen at random from two individuals are identical. In the mouse, the coefficient of relationship between parent and offspring is 50%, meaning half of the offspring's genome comes from that parent. Half the genes are identical by descent. The inbreeding coefficient from pairing parents x offspring is 25%. The inbreeding coefficient is roughly half the relationship coefficient.


Linebreeding differs from inbreeding by the pairings which are allowed for.

In linebreeding it is not allowed to breed for inbreeding coefficients higher than 12.5%.

The homozygous offspring showing the recessive trait has to be selected and crossed with other, unrelated partners again. If this procedure is repeated several times, the relationship between the original carrier and the offspring goes below 1% after some circles.


Not allowed for linebreeding:

parent x offspring 25%

full siblings x full siblings 25%


Allowed for linebreeding:

grandparent X grandchild 12.5%

half siblings x half siblings 12.5%

first cousins x first cousins 6.25%

great grandparent x great grandchild 6.25%

second cousins x second cousins 3.125%


2009-10-30 Umbrous: A case of dominance modification in mice


There is a phenotype of agouti mice called intermediate agouti, which is "in between" full agouti (A/*) and non-agouti (a/a) when umbrous is present, which can present as a thick black stripe down the back of an agouti mouse. The original full article is online, though it is poorly scanned. http://www.ias.ac.in/jarch/jgenet/40/229.pdf

This interesting paper was found by Jack Garcia. Thank you, Jack!