Studies On AmphiTCTP, AmphiG10 And Ribosomal Protein Genes Of Amphioxus, Branchiostoma Belcheri Tsingtaunese

Amphioxus is a species of Amphioxi, the only Class of Cephalochordata and has about 29 species alive now. The main species of amphioxus in our country is Branchiostoma belcheri Gray, including two subspecies: Branchiostoma belcheri and Branchiostoma belcheri tsingtauense.Amphioxus has a special evolutionary status in traditional classification and is important to the study of animal evolution. Researchers debate on whether Amphioxus is the living invertebrate relatives closest to vertebrate during evolution. One opinion is that Amphioxus is the closest living invertebrate relatives of the vertebrate in the world, the ancestor of vertebrate might be more or less like an amphioxus. This opinion is widely accepted now. First of all, amphioxus looks like a fish in shape and structure. Amphioxus has notochord, nerve tube and pharynx, which are considered as three basic characteristics of chordate. Amphioxus also has somites and muscular segmentation. Secondly, studies of neuroendocrinology and reproductive-endocrinology of amphioxus support this opinion. Hatschek's pit of amphioxus is the control and regulation center of endocrine, like the hypothalamus of vertebrate. Thirdly, evolutionary study of Amphioxus genes such as AmphiD1/beta, beta-microseminoprotein (MSP)-like gene, HOX₁, HOXb₁,HOX₃ also supports this opinion. Those genes of amphioxus have high identities with the homologous genes of vertebrate. The second opinion is: urochordata, not lancelet, is the closest extant relative of vertebrate. Amphioxus is not a close relative of either vertebrate or tunicata, but is more akin to echinoderms. This opinion was supported by genomic analysis. Although there is variance between these two opinions, both agree on solving the problem of the origination of vertebrate using methods of genomic evolution analysis. Therefore, it is very important and necessary to study evolution of...