Comparative Analysis Of Intermuscular Bones In Hybrid Of (Blunt Snout Bream×Topmouth Culter)((?))×Blunt Snout Bream((?)) And Its Parents

The top5aquacluture species are all Cyprinidae fish in China. However the large number of intermuscular bones inhibite accessed by international market, further devolpment of fish culture has been limited. The large number of intermuscular bones in Cyprinidae fish not only reduce consumption of fresh fish but aslo increase the difficulty and expense of further processing, which requier for genetic improvement. Thus the develop new species of Cyprinidae fish that has less intermuscular bones are very important. Intermuscular bones(Abbr. IB) are small, hard bone spicules, located in the muscular intervals on both sides of the vertebrae, consisting of membranous ossifications of connective tissue in the muscular septum. They are unique to teleost fish and more common in the low teleosts (non-spine fin fish). This small bone has gradually reduced during fish evolution. In the first Teleostei, a relatively simple form of intermuscular bone existed, with the evolution of fish from simple to complex it’s morphology has changed, and with the evolution of the cyprinids, in particular, intermuscular bone morphology has become extremely complex. Although there is much study of small intermuscular bone morphology in fish, but hardly any observational studies on the number, morphology, and distribution in intermuscular bone of new Cyprinidae species.Distant hybridization is hybrid between interspecific, intergeneric, even farther distant, and it makes it possible to transfer the genome of one species to another, which results in changes in phenotypes and genotypes of the progenies. The key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education of China in Hunan Normal University successfully produced partial fertile diploid individuals in the first generation by fish genus distant hybridization of Blunt snout bream (Blunt snout bream, ♀)×Topmouth culter (Topmouth culter,♂),called F1(hybrid of Blunt snout bream(♀)×Topmouth culter(♂)). And then we obtained (hybrid of (Blunt snout bream×Topmouth culter)(♀)×Blunt snout bream(♂)) by back crossing F1(♀)and Blunt snout bream(♂).Currently, the formation of the two generations hybrid provided good germplasm resources for future genetic breeding and the gain of the2nBTB showed good prospect for production of new kind of strains for aquaculture with the two kinds of hybrid strains.This kind of hybrid strain provided a biological platform for the comparative analysis of intermuscular bone in different ploidy fish. Our study exhibit the number, morphology, and distribution of intermuscular bone in four hybrid fishes which including Blunt snout bream Topmouth culter、 hybrid of Blunt snout bream(♀)×Topmouth culter(♂) and hybrid of (Blunt snout bream×Topmouth culter)(♀)×Blunt snout bream(♂). The results of this research will provide a morphological basis in both fish bone developmental biology and genetic breeding. The major results were presented as follows:1. The number of intermuscular bones in Topmouth culter, hybrid of (Blunt snout bream×Topmouth culter)(♀)×Blunt snout bream(♂), hybrid of Blunt snout bream(♀)×Topmouth culter(♂) and Blunt snout bream from126to136(=130),116to125(=120),121to139(=129), and112to119(=116),respectively.The number of intermuscular bones in Topmouth culter is larger than that in Blunt snout bream may directly caused by the larger number of vertebrate in Topmouth culter than Blunt snout bream.2. Taking the body size of different hybrid fish and the number of sarcomeres into account, the average number of intermuscular bones in each sarcomere was further analyzed; they ranked in order from highest to lowest, hybrid of Blunt snout bream(♀)×Topmouth culter (♂)(0.8100), Topmouth culter (0.7570), Blunt snout bream (0.7256) and hybrid of (Blunt snout bream X Topmouth culter)(♀) X Blunt snout bream(♂)(0.6971). In addition, the four kinds of fishes are significantly different from other three (P<0.05). That means Topmouth culter has less intermuscular bones in each sarcomere than other three fish that provides it a greater edible value under the same nutrition, size and other basic physiology condition.3. Intermuscular bone of these four fishes is divided into seven shape categories, non-forked(I),one-end-unequal-bi-fork(卜), one-end-equal-bi-fork (Y),one-end-multi-fork, two-end-bi-fork, two-end-multi-fork, and tree-branch types. Generally, more morphological complexity was seen in the anterior intermuscular bones than in those of the posterior body.4. The number of intermuscular bones was similar but not equal in the left and right sides of the body. The IB count also varied among different regions within the same individual.The results of this research show that hybrid of (Blunt snout bream X Topmouth culter)(♀) X Blunt snout bream(♂), which are the hybrid fish of the artificial cultivation, had less intermuscular bone than Topmouth culter and Blunt snout bream. The results of this research are of certain significance in both fish bone developmental biology and genetic breeding.