[Recent advances on sex determining mechanisms of Microtus mandarinus].

Most mammalian sex determination belongs to male heterogametic type of genetic sex determination. Sex determination of most mammals depends on the Y chromosome. SRY gene is the testis-determining factor on Y chromosome of most mammals, which is thought to be the most important gene in sex determination by far. Recent studies on Microtus mandarinus mandarinus demonstrated that the subspecies has Y chromosome, but there is no SRY gene on Y chromosome. Sex determination of Microtus mandarinus mandarinus is independent of SRY gene. R-spondin1 has also been excluded as the sex determination gene of Microtus mandarinus mandarinus. This paper reviews recent advances on sex determining mechanisms of Microtus mandarinus mandarinus. Possible sex determining mechanisms of Microtus mandarinus mandarinus in the absence of SRY gene are also discussed.

[An overview of phylogenetic relationship between Mus and Microtus].

Muriod is the most successful one among rodents struggling for existence, and biologists have been paying much attention to it, especially Mus musculus. Because of the thorough study on Mus musculus, it has been widely applied in lab, and becomes a good material for studying other animals. Phylogenetic relationship between different species and populations of Mus and Microtus are more clearly revealed with some genetic markers of modern genetics, such as protein, mtDNA, and rDNA. Taxonomy and evolution of species of both genus have also been revealed. Whereas the taxonomy and genetic relationships of some species and populations between both genus need to be further studied.

[A study on the karyotype, C-banding and Ag-NORs in Rana nigromaculata].

The chromosome samples of Rana nigromaculata were prepared by peripheral blood lymphocyte cultured in vitro. Karyotype, C-banding and silver-staining nucleolus organizer regions (Ag-NORs) were observed on chromosomes samples. The result showed that: (1) the chromosome number of Rana nigromaculata is 26 (2n=26), i.e., 10 large and 16 small chromosomes, the large chromosomes are matched into 5 homologous pairs and small chromosomes are matched into 8 homologous pairs, and further indicates the karyotype of Rana nigromaculata is bi-modal; (2) Metaphases of female and male were observed separately, the chromosome of No.11 has a pronounced secondary constriction in the middle of long arms. But the position of secondary constriction in the aberrant type individuals is in the middle of long arms of the No.8; (3) it has only one obvious C-banding close to the telomere, which is located in the long arms of the No.5; (4) The chromosome No.11 is a pair of homologous chromosomes with Ag-NORs, and the position of Ag-NORs in female and male is identical.

[The effect of CSN1 S2, CSN3 and beta-lg genes on milk performance in Xinong Saanen dairy goat].

PCR-RFLP technique was applied to analyze correlation between the polymorphisms of CSN1 S2 (alpha(s2) casein), CSN3 (kappa casein) and beta-lg (beta-lactoglobulin) genes and milk performance in 69 individuals of Xinong Saanen dairy goat. The results showed that there was significant correlation between different genotypes of CSN1 S2 locus and milk yield:average milk yield of individuals with genotype FF was less than that of genotype NN (P < 0.05); the second lactation milk yield of individuals with genotype NN was over 90 kg higher than that with genotype FF (P < 0.01). This indicates that allele F of CSN1 S2 locus probably has significant negative effect on milk yield. The results of CSN3 gene digested with endonuclease Hind III cleavage showed that no significant difference of milk yield between genotype DE and genotype EE was detected in first, second, third and fourth lactation milk yield and average milk yield (P > 0.05). The results of CSN3 gene with endonuclease Taq I cleavage showed that no significant difference of milk yield among individuals with genotype TT, TC and CC was detected (P > 0.05). No polymorphism was detected in PCR products of CSN3 gene digested with endonuclease Hae III. The analysis of beta-lg gene's 5' flanking region (710 bp) by PCR-RFLP in Xinong Saanen dairy goat showed that milk yield of individuals with genotype AA was higher than that with genotype AB in second, third lactation milk yield and average milk yield (P < 0.05). The results implied that allele A of beta-lg gene's 5' flanking region is probably related to high milk yield.

[Detection of Y chromosome in human and Microtus mandarinus with FISH].

The purpose of the investigation was to detect the Y chromosome of human and Microtus mandarinus with the satellite DNA probe in human's Yq by fluorescence in situ hybridization(FISH). We hybridizied the probe with the metaphase chromosome and interphase nucleus specimens of humanbeing and Microtus mandarinus respectively. The results showed that there was hybridization signal on metaphase chromosome and interphase nucleus of human, but no signal on metaphase chromosome and interphase nucleus of Microtus mandarinus. According to the results,we discussed the homologue between pY3.4 in Y chromosome of humanbeing and DNA of Microtus mandarinus and FISH result of Microtus mandarinus.

[A family history of vitiligo with autosomal dominant inheritance].

A family history of vitiligo was reported in this paper,and the reason causing disease was discussed. We think that the vitiligo in the family history is caused by autosomal dominant inheritance.