| First Author | Wallace ME | Year | 1970 |
| Journal | Mouse News Lett | Volume | 42 |
| Pages | 20 | Mgi Jnum | J:15065 |
| Mgi Id | MGI:63208 | Citation | Wallace ME (1970) his. Mouse News Lett 42:20 |
| abstractText | Full text of MNL contribution: Research News: Anomalies in Peru Mice. Our colony is purebred from specimens trapped for Dr. Wallace by Miss Olga Atteck in a Peruvian yard used to dry maize cobs (MNL 39, 17). It has reached 24 generations of more-or-less random mating within the small closed colony. Since no new anomalies have appeared since the 10th generation, those which appeared in the early generations are now summarised: (a) Size, agility and agouti colouring. These mice are typically very small, 12 g at 6 weeks, some males having bred at 10 g. They are also very agile (Wallace & Hudson, Lab. Animals 3, 107, 1969, where caging is described), easily jumping 16" from the ground. This is probably of selective advantage as cats were kept to reduce their numbers in the yard. Their agouti colouring is unusually yellowish and pale, again of probable advantage among the ripening cobs. They tend to "freeze" when frightened, and have very prominent eyes and large thin ears. Fl yellows, from Peru x sabled Ay from AG/Cam, were all unsabled. Fl yellow back-crossed to AG/Cam gave an approx. ratio 3 unsabled : 1 sabled (among yellows), but segregation in subsequent backcrosses was not clear-cut. While two dominant inhibitors of sabling would explain this, minor genes must also be involved. Selection for unsabled yellow, over many generations after the outcross, with selection against agility, succeeded with unsablei but failed with agility and the mice remained small. The relation between size and agility is probably physiological (MacArthur, Genetics 34, 194, 1949 and Falconer, Genet. 51, 470, 1953), but linkage with one or more colour factors is not ruled out. The provisional symbol is Cf (MNL 29, 21). No further investigation is planned. Their probable genetic adaptation to stress in a habitat of severe predation prompted the author's suggestion that these mice be used to study endocrine variation and other metabolic processes here (Spickett & Badr, Acta Endocrin. Kbh Supple. 100, 93, and Badr & Spickett Ibid 100, 92, 1965; Stewart & Spickett, Endocrin. 44, 417, and Shire Ibid 33, 2, 1965; and subsequent papers). b) Balance defect: Many Perus have shown circling behaviour (provisional symbol bla, MNL 30, 19). Crosses with sh-1, pi and fi have given normal progeny. Circlers were recovered in generations following an outcross to AG/Cam, and subsequent selection established a colony with 80% incidence of circlers. As the defect disappears on outcross and has a very low incidence in the first few backcrosses to the high incidence stock, the genetic basis is polygenic; variation of incidence between litters from the same mating indicates also an environmental component. Most circlers develop a rough sticky-looking coat with increasing age, a feature distinguishing it from other characters with a similarly polygenic basis such as "Zigzag" (Zg) and careener (Chai & Chiang, Genetics 47, 435, 1962). The selected stock of circlers will shortly be abandoned, but the pure colony may still give occasional specimens. |
