Allotetraploid Hybrids And Related Fish Mitochondrial Dna Restriction Analysis

The mitochondrial DNAs (mtDNAs) from livers of red crucian carp, common carp, F, hybrid of red crucian carp (♀) × common carp(♂), F2 hybrid, allotetroploid crucian carp, triploid crucian carp, Japanese crucian carp, C. auratus auratus&n& ovary of Japanese crucian carp were isolated by the means of differential centrifugation and nuclease digestion, then purifing them by means of phenol extraction. After having been digested by 9 restriction enzyme recogenizing 6 base pairs: Eco R I, Hind III, Pstl. Bglll, BamH I. Xho I, Xbal. Sal I and Kpn I,the mtDNAs were analysed by using agarose gel electrophoresis and detected by Gel-Pro Analyzer. The size of mtDNAs for red crucian carp, common carp, F, hybrid, F2hybrid, allotetroploid crucian carp, triploid crucian carp, Japanese crucian carp and C. auratus auratus were 16. 19kb ± 0. 13, 16. 61 ± 0.05kb, 16. 02 ± 0.09kb, 16. 02 ± 0. 09kb, 16. 20 ± 0.10kb, 16.24 ± 0. 14kb, 16. 60 ± 0. 09kb and 16. 06 ± 0. 17kb respectively. Based on the number and size of the restriction fragments abtained by single or double enzyme digestion, the physical map of mtDNA from allotetraploid crucian carp of 7 kinds of restriction endonucleases (Pst I. Bgl II, Bam H I> Xho I, Sal I and Kpn I) was constructed, which laid a foundation for analysing further the heretidy and evolution of allotetraploid crucian carp and other correlated fishers. At the same time, the improvement ofmtDNAs extraction and purification conditions and the method estimating molecular size were also studied.Using "Mathematical model for studying genetic variation in terms of restriction endonucleases", established by Nel and Li (1979), calculated the proportion of shared restriction fragments (F) and the genetic distances (P) between populations. The results manifested that there was minor genetic divergence between original maternal red crucian card and F1 hybrid, F2 hybricK allotetraploid crucian carp, but there was obvious genetic divergence between paternal common carp and Fi hybrid, F2 hybrid, allotetraploid crucian carp. The digestion result between F1 hybrid and F2 hybrid was unanimous, and mtDNA showed completely real heredity. .With the same mathematical model, the proportion of shared restriction fragments (F) and the genetic distances (P) of triploid crucian carp and its parent were calculated. By comparing the genetic distance of three populations, the genetic distance between triploid crucian carp and maternal Japanese crucian carp was smallest (P=0. 62). The genetic distance between triploid crucian carp or Japanese crucian'carp and allotetraploid crucian carp(I-type) were 1.97 , 2.76 respectively. According to the endonucleases digestion results of mtDNAs from C. auralus auratus and other strains, the hereditary and evolutional relation of several populations was analysed.The statistical analysis of restriction fragments of several inter- species or inter-populations showed that mtDNA followed the character of matrilinear inheritance in crossing breeding. The two different breeding ways(breeding allo- tetraploid and allotriploid) could not only be regarded as the model ofresearching matrilinear inheritance of mtDNA, but could offered accurate testimony for concisely analysing mtDNA paternal leakage and leakage inheritance. From the point view of mtDNA evoltion and according to mtDNA the evolution rate being raised by Brown and his coleague,we can draw conclusions that allotetraploids and allotriploids gained from the natural evolution, they need 5 million years , 1 million years respect ively.