| aberrant sex chromosome mechanisms in mammals. evolutionary aspects. | there are a number of mammalian species with complicated or unknown mechanisms for sex determination. the literature is reviewed with special reference to the origin and evolution of the sex chromosome mechanisms in three species of monotremes and in the following species of rodents: the creeping vole (microtus oregoni), the mole vole (ellobius lutescens), the amami spinous country rat (tokudaia osimensis), the wood lemming (myopus schisticolor), the varying lemming (dicrostonyx torquatus), sout ... | 1983 | 6444170 |
| aberrant chromosomal sex-determining mechanisms in mammals, with special reference to species with xy females. | both mouse and man have the common xx/xy sex chromosome mechanism. the x chromosome is of original size (5-6% of female haploid set) and the y is one of the smallest chromosomes of the complement. but there are species, belonging to a variety of orders, with composite sex chromosomes and multiple sex chromosome systems: xx/xy1y2 and x1x1x2x2/x1x2y. the original x or the y, respectively, have been translocated on to an autosome. the sex chromosomes of these species segregate regularly at meiosis; ... | 1988 | 2907806 |
| natural exceptions to normal gonad development in mammals. | gonads are the only organs with 2 possible developmental pathways, testis or ovary. a consequence of this unique feature is that mutations in genes controlling gonad development give rise not only to gonadal malformation or dysfunction but also to frequent cases of sex reversal, including xy females, xx males and intersexes. most of our current knowledge on mammalian sex determination, the genetic process by which the gonadal primordia are committed to differentiate as either testes or ovaries, ... | 2013 | 22626995 |
| sperm dna and sex chromosome differences between two geographical populations of the creeping vole, microtus oregoni. | the relative dna content of the "o" and y chromosome-bearing sperm is presented for the creeping vole, microtus oregoni. the animals had been trapped in oregon and in washington state. the two populations had very similar autosomal chromosome relationships but differed greatly in the size of their x chromosome (which is not carried by vole sperm) and in their y chromosome. the greater size and banding differences of the y chromosome of the washington state vole compared to the oregon vole parall ... | 1990 | 2248779 |
| a model of the evolution of the unusual sex chromosome system of microtus oregoni. | in the creeping vole, microtus oregoni, females are x0 and males are xy. in the female germ line, mitotic nondisjunction ensures that the products of meiosis all carry the x chromosome. similarly, mitotic nondisjunction in the male germ line leads to the production of 0 and y sperm. we propose that the present situation in m. oregoni has evolved by invasion of a normal xx/xy system by a mutant x chromosome, x', with a complete transmission advantage in x'x females, and a complete transmission di ... | 2001 | 11520338 |
| sex chromosomes, sex determination, and sex-linked sequences in microtidae. | the arvicolidae is a widely distributed rodent group with several interesting characteristics in their sex chromosomes. here, we summarize the actual knowledge of some of these characteristics. this mammalian group has species with abnormal sex determination systems. in fact, some species present the same karyotype in both males and females, with total absence of a y chromosome, and hence of sry and zfy genes. other species present fertile, sex-reversed xy females, generally due to mutations aff ... | 2003 | 14684993 |
| the creeping vole, microtus oregoni: karyotype and sex-chromosome differences between two geographical populations. | the g-banded karyotype of the creeping vole, microtus oregoni, prepared from animals trapped in oregon and washington, is presented. the two populations had similar autosomal banding patterns but exhibited striking differences in their sex chromosomes. the x chromosome of voles captured in oregon was 39% longer than that of voles trapped in washington. the length difference was primarily due to an increase in size of light g-bands, which, in both populations, comprised large segments of the x ch ... | 1988 | 3046846 |
| sex preselection in mammals? separation of sperm bearing y and "o" chromosomes in the vole microtus oregoni. | the two sex determining sperm populations of the vole microtus oregoni were separated according to dna content by use of flow sorting instrumentation. although the sperm were not viable, they should be useful for addressing the question of haploid expression of genes linked to sex chromosomes and for efficiently searching for biochemical markers that differentiate the two populations. | 1982 | 6753153 |
| the creeping vole (microtus oregoni) as a gonosomic mosaic. i. the oy/xy constitution of the male. | | 1963 | 14104168 |