Background: The breeding performance is an important parameter to evaluate the breeding success in captivity conditions. The optimum dose of hormone in combination with latency period is desirable for getting best breeding performance in fish. Objectives: The objective of the study was to find the spawning latency period in the hormonal induced reproduction of Snow trout with two inducers (Ovaprim and hCG) separately and in combination. Materials and Methods: The fish spawners were randomly divided into five groups and treated with Ovaprim, Ovaprim and high dose of hCG, Ovaprim and low dose ofhCG, hCG and saline water as control. Results: The results suggested that Ovaprim and high dose of hCG treatment lead to shorter latency time (40 hours and 40 minutes), but ovulation percent, percentage of live embryos in the eyed stage and ovulation synchronization were lower than treated groups with Ovaprim alone or Ovaprim and low dose of hCG. Females from the control and hCG groups did not spawn. Conclusions: The highest hormonal stimulation effectiveness was recorded in the group in which one hormonal substance (Ovaprim) was applied. Therefore the accurate ovulation time of snow trout, Schizothorax zarudnyi was difficult to be predicted.
The in vivo effect of 11-ketotestosterone (11KT) on transcript levels of the gonadotropin receptors (fshr and lhr) and sex differentiation-related genes (dmrt1 and foxl2) was examined in the ovaries of immature female beluga. For this purpose, six fish were treated with implants containing 2.5 mg 11KT and a placebo group of six females of the same age and gametogenic stage were given a blank implant. The implants were intraperitoneally inserted into 4-year-old females at the previtellogenic stage (mean body weight 5580 ± 165 g) and maintained under culture conditions for 8 weeks. Ovary samples for gene expression analysis of lhr, fshr, dmrt1 and foxl2 were collected by biopsy at 3 and 8 weeks post implantation. Diameters of oocytes increased in response to 11KT treatment, both at 3 and at 8 weeks post implantation, but no obvious changes were evident in cytology. Three weeks of 11KT treatment did not affect target gene expression, but a tendency for a time-dependent decrease of lhr and dmrt1 mRNA levels was observed in both treatment and placebo groups. By 8 weeks of treatment, however, 11KT implants provoked the upregulation of fshr and foxl2 transcript levels. Furthermore, lhr and dmrt1 transcript abundances recovered by 8 weeks of exposure in both blank-and 11KT-implanted beluga. These results suggest that 11KT, either directly or indirectly, may affect gametogenesis and regulate some key components of the reproductive axis in female beluga.
The development of digestive tract and accessory glands in Hamun mahi (Schizothorax zarudnyi, Family: Cyprinidae) from hatching to 21 days after hatching (DAH) is described in this study. This information is critical for evaluating the digestive tract functional capacity and physiology of digestion in larvae, and designing optimal rearing techniques and artificial diets for this commercially valuable species. Based upon its feeding mode and structural changes in the digestive tract, larval ontogeny in S. zarudnyi was divided into three stages, Stage 1: 0-2 DAH, Stage 2: 3-8 DAH and Stage 3: from 9 DAH onwards. As in most teleosts, Hamun mahi at hatching had an undifferentiated digestive tract. The most critical ontogenetic events occurred at Stage 2. At the beginning of Stage 2, mouth opened in conjunction with the differentiation of the digestive tract. During Stages 2 and 3 the gut differentiated, and buccopharyngeal cavity, oesophgus and incipient intestine became distinguishable. At this stage digestive tract processes continued to develop (e.g. entrocyte's brushborders, appearance of digestive mucous cells at 4 DAH, and gut mucosal folds). The first taste buds and pharyngeal teeth appeared at the beginning of Stage 2. Histological observations suggest that digestive tract development of the Hamun mahi larvae, involving the presence of functional liver (vacuolated hepatocyes), exocrine and endocrine pancreas, and gallbladder enabled early larvae (from 3 DAH) to ingest, digest and assimilate the first exogenous food, even before endogenous reserves were completely resorbed. From Stage 3 onwards, most organs essentially exhibited an increase in tissue structure, size and number.
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