The Study Of The Influence And Mechanism Of Sea Water Temperature On Gonadal Development And Reproductive Activity Of Amphioxus

Amphioxus or lancelet, a cephalochordate, is the extant invertebrate most closely related to the proximate ancestor of vertebrate, and has long been regarded as the model animal for insights into the evolution of vertebrate and developmental homology analysis. In this paper, we studied the influence of sea water temperature on the gonadal development and reproductive activity using the method of experimental biology, meanwhile, we studied its mechanism by the way of immunohistochemistry and magnetic enzyme immunoassay.From 12/27/2006 to 4/5/2007(110 days) and 12/25/2007 to 3/9/2008(75 days), the amphioxuses in the gonadal period of reproductive cycle were cultured in 16℃,22℃,28℃respectively. The result showed that amphioxuses of the highest temperature group gained remarkable gonadal enlargement than the other two groups. Further study of the gonadal phase of each group showed that in the highest temperature group there were more amphioxuses of the large phase of growth than the other two groups. The immunohistochemistry showed that the immunohistochemisty intensity and the quality of reactive cells of GnRH in brain and LH in Hatschek's pit is stronger and larger with the rise of the gonadal phase. The immunohistochemisty intensity and the quality of reactive cells of aromatase in the brain is remarkably stronger and larger when the gonad is developed into the small phase of growth, and is maintained in a high level among the whole growth phase. The immunohistochemisty intensity and the quality of reactive cells of FSH in Hatschek's pit is strongest in small phase of gonadal growth. The AR and ER reactive cells were found in the early period of the gonadal development, and their quantity rise with the gonadal development.From June 10 to July 10 of 2007 and the same period of 2008, amphioxuses in the later period of large phase of gonadal growth and maturation phase were cultured in 16℃,22℃,28℃to study the spermiation and ovulation. The result showed that spermiation and ovulation were promoted in 28℃, and were inhibited in 16℃and 22℃.Magnetic enzyme immunoassay showed that testosterone and estrodiol level in amphioxus was high between the small and large phase of gonadal growth, and was much more lower in other phases. They can't be detected when the gonad is not developed.In this paper, the influence and mechanism of sea water temperature on gonadal development and reproductive activity of amphioxus was preliminarily studied by means of experimental biology,immunhistochemisty and magnetic enzyme immunoassay. It can give data to the further study on reproductive endocrinology of amphioxus.