Gonad Development And Research Of Sox14 Genne In Andrias Davidianus

The Chinese giant salamanders Andrias davidianus is an important species in the processof evolution and it also has the high economic value and scientific research value in china. Due to long-term neglect of the natural environment protection and illegal hunting, the wild resources are being dramatically declined, making it anendangered species. At the beginning of the 21 st century, along with further attenuation of giant salamander resources and market price rising, farmed giant salamander rise gradually, has become a part of characteristic industries.But, due to the lack of basic research on breeding of giant salamander,combined with the appearance of the uniqueness of gonad development and reproduction,made the appearance of artificial breeding technology has been no big breakthrough.Among them, the non-synchronous development of male and female salamanders gonad is a major cause of lead to low reproduction rate, also a bottleneck of salamander breeding technology.For insight into the gonad development regularities and reproductive characteristics of A.davidianus, we carried some preliminary study on the tissue characteristicsof the pituitary and testis, hormone levels and metabolism intensity, as well as Sox14 gene structure and expression characteristic inA.davidianus. The results obtained are as follows:1.By tissue slice observation, the result shows that: similar to fish and other amphibians,the pituitary gland of A.davidianusalso include neurohypophysis and adenohypophysis.Adenohypophysis including pars tuberalis, pars intermedia and pars distalis.The pars intermedia is more flourishing.According to the cell’s color,thepars distalis can be divided into basophilic area, acidophilic area and mixed area.with the long and narrow tube cavity,the seminiferous tubule of A.davidianus united to form a testis-net. The development of sperm cells are not synchronized in same individual,testis development is out of sync between different individuals.both of this two reasons lead to low induced spawning rate and fertilization rate of A.davidianus.2.Hormone level testing found that the development of AD’s gonad has the following three characteristics:(1) the gonad development regularity of viripotent male and femaleA.davidianusare basicallycoincident. with the temperature rising,serum hormone levels increased in spring, peaked in June and began to reduce after that.It’s suggests that under the condition of artificial breeding male and female AD’s gonad development is synchronous, but the breeding season is too short.(2) the gonad development of viripotent male and female A.davidianus have different sensitivity to temperature.The testosterone levels of MaleA.davidianus vary with temperature variation sharply,but the female react gently.It’s suggests that the male AD’ gonad development more sensitive to temperature.(3)The hormone level of viripotent male and female A.davidianushave a great difference between different individuals. It may be one of the reasons for low reproduction rate in A.davidianus.3.The measured results of the serum biochemical indexes show thatthe concentration of total cholesterol(TC),triglyceride(TG), HDL-c and LDL-c in females were higher than males.Thus,these differences of serum biochemical indexes between males and females have a guiding significance for sex-testing and gonad development period in A.davidianus.The peak of BUN concentration of males and females appeared out of sync.It meight be one of reason that the gonad development of males and females are not synchronized.4.The experimental results of sensitivity to aphrodisiac in A.davidianus show thatboth of the viripotent male and female A.davidianus are sensitive to HCG.The hormone level rised to the highest after injected HCG 24 hours, then began to decline.on the contrary,both of the viripotent male and female A.davidianus are sensitive to LH-A2. The hormone level have no obvious change after injected LH-A2 within 48 hours.It’s suggest that HCG is best for artificial propagation ofA.davidianus.5.The bioinformatics and researchs on gene expression of AD’Sox14 show that the full cDNA sequence of Sox14 of A.davidianus is 1470 bp, with an open reading frame(ORF) 720 bp,coding 239 AAwhich pI is 9.68 and molecular weight is 26.75 kd.Homology comparison showed Sox14 was very conservative, and thehomology compared withX.topiciles is 91%,the homology compared with fish and humanbeings is 80~90%.Sox14 was highest expressed in gonad of viripotentA.davidianus.Express quantity increased with the increase of the age.Above reasearch resualts show that:(1)thegerm cell development out of sync in the pituitary testis may be the main cause of low reproduction rate inA.davidianus.(2) the gonad development of A.davidianus in artificial aquaculture is basically synchronous,but males are more sensitive to temperature change. Both of the males and females are sensitive to HCG,HCG can be used for artificial oxytocininA.davidianus.(3)Sox14 genes are expressed mainly in the gonad of viripotentA.davidianus.Thus,Sox14 genesis associated withthe gonaddevelopment, it can be used as a marker gene of gonad developmentinA.davidianus.