The Tufted Deer (elaphodus, Cephalophus) Kernel-type Polymorphism, Susceptibility To Environmental Factors, And The Case Between The Evolutionary Relationship

The cell strain from the skin cells of a male Elaphodus cephalophus was established by primary culture and subculture. Analysis of chromosome showed a new karyotype. There were 24 pairs of chromosomes in somatic cell, including one pair of heteromorphic chromosomes which lengths were different from corresponding chromosomes in other karyotypes reported. They were marked with "a" and "b" chromosomes respectively, "a" chromosome had rich heterochromatin by C-band, and "b" was a large subtelocentric chromosome almost consisting of heterochromatin. G-band analysis showed there were some faintly-stained bands in the hereochromatinic regions of the pair of chromosomes.With comparasion of chromosome relative length, ratio of arm and proportion of heterochromatin among three karyotypes, combining other karyotypes existed, we discussed the chromosome polymorphism of Elaphodus cephalophus. The karyotype polymorphism was mainly caused by "a" and "b" chromosomes, which differed in chromosome number, morphisniN length and proportion of heterochromatin, etc. The proportion of heterochromatin is between 78.58%-89.99%, and the proportion became higher with the longer chromosome. Besides, we discussed on the sex chromosome and the mechanism of sex determination of Elaphodus cephalophus.To find out the reasons of chromosome polymorphism of Elaphodus cephalophus , we analysed the effect of different environmental factors (including low temperature, high temperature, ultraviolet radiation and MNNG) on karyotype polymorphism. The chromosome number variation (48.77%-75.31%) and polyhaploid (10.47%-44.19%) and some structure variation were defected in the cell strains which were preserved in liquid nitrogen for different periods of time. The sensitivity of different cell strains to low temperature were different, and the karyotype variation time was correlative with cell frozen preserving time. After treated with high temperature, ultraviolet radiation and MNNG, cell strains of Elaphodus cephalophus changed in karyotype and polyhaploid number. The result proved that the karyotype of cell strains of Elaphodus cephalophus was unstable and environmental factors took a role on the unstablity. The karyotype variation and polymorphism mainly focused on "a" chromosome, so we considered that the polymorphism of the cell strain ofElaphodus cephalophus was caused by "a" chromosome.For the identification of sex chromosome and studying sex determination mechanism of Elaphodus cephalophus, we amplified the SRY gene fragment of Elaphodus cephalophus, Muntiacus crinifrons and Muntiacus reevesi homologous to Muntiacus muntjak SRY by PCR with Muntiacus muntjak SRY gene primers. Each fragment of PCR products had 630 base pairs in length by direct sequencing. The nuclearted divergence of the SRY region was 0.79%-1.90% among three species of Muntiacus, 3.02%-3.97% between Elaphodus and three species of Muntiacus. The divergence time was about 79-190 Myr among three species of Muntiacus, Elaphodus diverged from Muntiacus about 302-397 Myr ago, and Cervus nippon diverged from Muntiacus about 349-460 Myr ago. The SRY sequences of Cervus nippon and Bovidae bonasus came from Genebank. Bovidae bonasus was as outgroup, the phylogenetic tree was contructed by neighbor-joining method and maximum parsimony method and the phylogeny relationship of the 5 kinds animals of Cervidae was analyzed. The phylogeny relationship between Elaphodus cephalophus and Muntiacus from SRY gene was consistent with their phylogenetic study of mitochondrial cytochrome b gene.