The Reproductive System And Karyotype Analysis Of Ovomermis Sinensis

Ovomermis sinensis is a kind of entomopathogenic nematodes. It can live on the larva of Lepidoptera positively, and assimilate the nutrition until host death, parasitic rate equal to mortality rate, it can effectively kill the pests which endanger the growth of crops (cotton, vegetables), therefore, it is a very valuable and important resources of biocontrol.Chromosome numbers, morphological structure characteristics for creature is specific, karyotype analysis has an important role in the classification of organisms, which is an important basis for classification of flora and fauna. And it is of very great significance to study mechanism of sex determination. As we know, nematodes gender decision? mechanism includes genetic sex determination (GSD) and environmental sex determination (ESD). GSD refers to the sex of nematode is controlled and determined by a signaling pathway which is composed by a number of genes, There are two major types, XX/XO and XX/XY, mostly is XX/XO. ESD refers to the sex of nematode is determined by their living environment, such as temperature, the density of infection and nutritional conditions, and so on. The sex of O. sinensis is determined by host nutrition, it is also a very special mechanism of sex determination, when the low density of nematode infection, single nematode can get more nutrition, then they are female, otherwise, they are male.In recent years, researchers go into studying the mechanism of sex determination of O. sinensis in molecular biology and biochemical level, they come a long way and have a certain understanding to determination mechanism of mermithidae. But so far, no one study in cytogenetic. In this study, author study O. sinensis mechanism of sex determination in cytogenetic, moreover, researcher have a rough morphological description of O. sinensis reproductive system, it is first dissecting the reproductive system of O. sinensis, morphology results show that it similar to other dioecious nematodes. In O. sinensis females, the reproductive system consist of oocyte, ovary, oviduct, spermatheca, uterus and vagina(vulva); in O. sinensis males, it includes spermatocyte, testis, vas deferens, seminal vesicle, ductus ejaculatorius and spicule. The karyotype analysis results show that the chromosome numbers of female is n=6,2n=12, the chromosome numbers of male also is n=6,2n=12, the chromosome numbers are identical between males and females. And there is no significant difference in chromosomes. Moreover, no apparent sex chromosomes and satellites were observed in this study, it indicates that O. sinensis is ESD, which is consistent with previous research. In a word, it is important impetus to further explore to study sex determination mechanism of mermithidae by studying O.sinensis in cytogenetic, but aslo it can provide an important basis for cytoplasmic genetics research of O.sinensis...