Studies On Reproduction Physiology And Some Biological Characteristics Of Pelteobagrus Fulvidraco

In this paper, Reproduction Physiology and some Biological Characteristics of Pelteobagrus fulvidraco of Dongting Lake in Hunan Province were studied by the method of histological section and ultramicrotomy, chromosomes preparation, PAGE ( polyacrylamide gradient gel electrophoresis ) and PCR (Ploymerase Chain Reaction). The main results and conclusions were as follows:1 . With the method of the histological section, the morphology, histology and annual cyclical changes of ovary in Pelteobagrus fulvidraco were observed. According to the morphological and histological features, the development of ovary can be devided into six stages and the change of the oocytes of the female can be devided into six phases. The ovaries are in stage I when the fishes are 30 to 60 days old and only appears once in their life. When they are 60-270 days old, the ovaries began to grow to stage II and the yolk nucleus are very distinct. When they are 270-300 days old, the ovaries enter into stage III, the unilayer vacuoles can not be seen in the stage III. The ovaries grow to stage IV when they are 310 days old, the micropyle and the micropylar cell are very clear. After 330 days old, the fishes reach to sexual maturation. The mature coefficent of ovaries is 10. 9%-26. 5%. The maturation age of female is 1 year old. The breeding season of Pelteobagrus fulvidraco is from May to July. The results of this paper indicate that this fish spawns only once a year.2 . The development and annual change of testis, spermatogenesis and spermatoleosis in Pelteobagrus fulvidraco were studied with the method of histological section and ultramicrotomy. According to the morphological and histological features, the development of testis can be devided into six stages. The testis is stage I in 30 days to 60 days oldand stage II in 60 days to 90 days old and stage III in 90 days old and it grows to stage IV in 150 days to 200 days old. After 300 days old, the fishes reach to sexual maturation. The mature coefficient of testis is 0. 3%-0. 65%. The maturation age of male is 1 year old. The breeding season of the fishes is from May to July. The results of this paper indicate that the male appears for twice. The spermatogenesis and spermatoleosis are from spermatogonia, through the following stages including spermatogonium , spermatocytes, spermatids and spermatozoa. The spermatozoa have no acrosome. The tail is long, mitochondria and lateral fins are very developed. The f lagellum shows a typical microtube organization "9+2" in the view of cross-section.3. The histological and ultrasstructure of pituity gland from sexually matured female Pelteobagrus fulvidraco were studied. The pituitary gland consisted of neurohypophysis and adenohypophysis. The adenohypophysis was devided into anterior lobe, intermediate lobe and posterior lobe. There aretwo types of cells including the acidophile and the basophile. Prolactin cell (PROL) and adrenocorticotopic hormone cell (ACTH) exist in the anterior lobe, the gonadotropic hormone cell (GTH), growth hormone cell (GH) and thyrotropic hormone cell (TSH) exist in the intermediate lobe, the posterior lobe cosists of melanotropic stimulating hormone cell (MSH).4. The Sox genes of Pelteobagrus fulvidraco were amplified and cloned using Ploymerase Chain Reaction(PCR) with primers designed according to the known SRY or Sox sequence from the Human genomic DNA and other animal genomic DNAs. We selected five different fragment of Sox gene HMG-box DNA and sequenced, the length of sequences is 220bp or so. The results indicated that Sox gene was conservative in evolution, in which the nucleotide sequences have about 85% or above 85% identical toother animals ( Human, Mus, Chicken and Zebrafish), the amino acid sequences encoded by PFSox have about 94% or above 94% identical to those encoded by other animals (Human, Mus , Chicken and Zebrafish). The nucleotide and amino acid sequences identities of Sox gene fragments of Zebrafish or Alligator from Genebank were compared with the Sox gene fragments of Pelteobagrus...