Studies On Germplasm Characters Of Triplophysa Xiangxiensis

At present,the germplasm research of cavefish is still in the blank stage.There were many reasons such as sampling difficulty,personal safety and scarce resources,and so on. The study on a cave fish,Triplophysa xiangxiensis,is lack of germplasm identification and still at the level of classification.For protecting and exploiting the fish genetic resources,this experiment studied several kinds of idioplasmic characters of Triplophysa xiangxiensis.This paper studies the main morphological character,the genetic character of chromosomes and the physiology and biochemistry of genetic character of Triplophysa xiangxiensis.The result shows as the follows:1.The main morphological characterTriplophysa xiangxiensis is described from external form,countable character and metrical proportional character by the observation of its exterior character and the measurement of traditional morphology.Triplophysa xiangxiensis has general characters of typical troglobite fishes.The result showed there areⅲ-8 dorsal fin-rays,ⅲ-6 proctal fin-rays,ⅰ-11 pectoral fin-rays,ⅰ-6 ventral fin-rays,16 caudal fin-rays in countable characters.The average ratio(+SD) of TL/BL,BL/BD,BL/HL,BL/CPL,BD/BW,CPL/CPD,HL/SL and PFL/BL were 1.21±0.03,5.44±0.47,3.74±0.49,5.94±1.08,1.17±0.22,3.34±0.76,3.88±0.50 and 0.34±0.10 in comparatives of measurable characters.2.The genetic character of chromosomesThe chromosomes of Triplophysa xiangxiensis were prepared directly from the kidney cell of lively fish.The analysis of the result shows that there are 48 chromosomes in diploid number of Triplophysa xiangxiensis,and there are 12 metacentric chromosomes(m),16 submetacentric chromosomes(sin),12 subtelocentric chromosomes(st) and 8 telocentfic chromosomes(t).Thus the karyotype formula is 2n=12m+16sin+12st+8t,NF=76.3.The physiology and biochemistry of genetic characterThe genetic diversity of a population of Triplophysa xiangxiensis were detect by using vertical polyacrylamide gel electrophoresis(PAGE).Among the 21 loci in 7 isozymes(LDH,MDH,ME,EST,ADH,GDH and G-6-PDH) of six tissues examined,3 were polymorphic.Mean proportion of polymorphic loci was 14.29%and the observed heterozygosity was 0.0483.The expected heterozygosity was 0.0514.The genetic deviation index(d value) was -0.0603.The Chi-Square test showed that all polymorphic loci were not in Hardy-Weinberg equilibrium and existed heterozygote deficiency.The results showed the population of Triplophysa xiangxiensis has a low genetic diversity, and inbreeding may give rise to it.