Application Of Nuclear Gene C-mos In Molecular Phylogenctic Studies And Construction Of Bacterial Artificial Chromosome Library Form The Mitten Crabs

The present thesis includes mainly two parts. 1. Application of nuclear gene c-mos in molecular phylogenetic studiesThe molecular markers to reconstruct phylogenetic relationships should meet some conditions. What are commonly used are mitochondrial DNA sequences and some nuclear gene sequences. We introduced here a nuclear gene c-mos. This is a kind of single copy nuclear gene with no introns, totally 1 kb or so. It is now mainly applied in the phylogenetic studies of reptiles and avians.The present study investigated the application of nuclear gene c-mos in higher level phylogeny among lizards, caenophidian snakes and amniotes respectively. Lacertilia phylogenetic relationship was reconstructed using minimum evolution method in MEGA2.1, and many families and subfamilies come out as monophyletic groups: Iguanidae, Xantusiidae, Scincidae, Lacertidae, Gekkonidae, Eublepharidae, Pygopodidae. Agamidae is clustered with Chamaeleonidae. Gerrhosauridae is clustered with Cordylidae. Shinisaurus crocodilurus is clustered with Varanus salvator. The result suggests that the amphisbaenians should be Included in the Scincomorpha and does not surport Shinisauridae to be a separate family but a subfamily level. The phylogenetic trees of caenophidian snakes were obtained using maximum likelihood method, maximum parsimony method in PAUP 4.0b8 software and minimum evolution method in MEGA. The result is consistent with result based on mitochondrial sequences that Elapids is closer to Colubrids; viperids is the sister group of Colubrids plus Elapids. The position ofEnhydris (Colubridae: Homalopsinae) in Colubridae is questioned in the study and we support the homalopsines be recognized as a separate family. The relationship among amniotes was reconstructed using maximum likelihood method in TREE-PUZZLE 5.0 software, maximum parsimony method in PAUP 4.0b8 software and minimum evolution method inMEGA2.1. The result suggests that mammals, turtles, birds and squamates are monophyletic. Mammals are the sister group to other amniotes. Squamates are the most basal living reptiles. Meanwhile, the study suggested that different methods should be applied in the reconstruction of molecular phylogeny.Additionally, we searched the database (http://www.sanger.ac.uk) using TBLASTN with the human MOS protein sequence and found one apparent MOS-like sequence (p<2.4e-13) in C. elegans. The structure and evolution of MOS in animal kingdom are discussed.2. Construction of bacterial artificial chromosome library from the mitten crabsThere are many vectors used in the construction of genomic library. Among them, bacterial artificial chromosome is more and more preferred recently because of its high cloning efficiency, easy manipulation, large insert and stable storage.Eriocheir japonicus is a kind of edible crab in China. Recent studies mostly based on its morphological characters. The intention of constructing the BAG library is to cooperate the ongoing studies on the mitten crabs at molecular level. But the construction of the library has not been completed yet.