Mice homozygous for the yellow spontaneous mutation (Ay) die before implantation or shortly thereafter. The time of death and type of abnormality is, in part, determined by the genetic background on which the mutation is placed. Hair pigment in heterozygous mice is yellow, but eyes are black. Heterozygotes usually become obese and infertile after the first few months. Increased adipose tissue mass is due to fat-cell hypertrophy. It has been hypothesized that the obesity results from the observed reduction in hypothalamic norepinephrine and dopamine levels. Insulin resistance and hyperglycemia follow development of hyperinsulinemia in early adulthood, although the degree is less severe than on the KK/UpJ genetic background (Stock No. <a href="https://www.jax.org/strain/002468">002468</a>). Heterozygotes are also more susceptible to several kinds of tumors than normal mice, and their spleen cells cause a significantly lower graft vs. host reaction. The level of malic enzyme in the liver is elevated.

Nonagouti; agouti yellow (Ay) is a semidominant spontaneous mutation with homozygotes dying before implantation. Heterozygotes are characterized by obesity, yellow hair pigment, black eyes, elevated malic enzyme in the liver, and susceptibility to several kinds of tumors.

Typically mice are recovered in 12-16 weeks. Contact Customer Service to place an order or for more information.

<a target="_blank" href="https://www.jax.org/jax-mice-and-services/customer-support" rel="noreferrer">Contact Customer Service</a> for more information.