The mandarin vole, Lasiopodomys mandarinus, is one of the most intriguing species among mammals with non-XX/XY sex chromosome system. It combines polymorphism in diploid chromosome numbers, variation in the morphology of autosomes, heteromorphism of X chromosomes, and several sex chromosome systems the origin of which remains unexplained. Here we elucidate the sex determination system in Lasiopodomys mandarinus vinogradovi using extensive karyotyping, crossbreeding experiments, molecular cytogenetic methods, and single chromosome DNA sequencing. Among 205 karyotyped voles, one male and three female combinations of sex chromosomes were revealed. The chromosome segregation pattern and karyomorph-related reproductive performances suggested an aberrant sex determination with almost half of the females carrying neo-X/neo-Y combination. The comparative chromosome painting strongly supported this proposition and revealed the mandarin vole sex chromosome systems originated due to at least two de novo autosomal translocations onto the ancestral X chromosome. The polymorphism in autosome 2 was not related to sex chromosome variability and was proved to result from pericentric inversions. Sequencing of microdissection derived of sex chromosomes allowed the determination of the coordinates for syntenic regions but did not reveal any Y-specific sequences. Several possible sex determination mechanisms as well as interpopulation karyological differences are discussed.
In animal populations inhabiting ecologically suboptimal environmental conditions, phenotypical shifts in physiological traits responsible for coping with environmental challenges can be expected. If such variations are of heritable origin, then they will manifest themselves even in individuals bred in captivity. In laboratory-born red-backed voles (Myodes rutilus (Pallas, 1779)) originating from a population with constantly low density, maximum cold-induced metabolic rates were higher than in voles from a high-density population, similar to the data obtained on wild-caught individuals from the same populations. However, unlike wild-caught voles, in laboratory-born individuals maintained under comfortable conditions, we revealed no interpopulation differences either in basal plasma corticosterone level or in corticosterone response to acute cooling. These data confirm the suggestion about the heritable origin of increased maximum cold-induced metabolic rate in a red-backed vole population with relatively low density.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.