Maw-Sheng Yeh

Cold shock-induced norepinephrine triggers apoptosis of haemocytes via caspase-3 in the white shrimp, Litopenaeus vannamei.

The total haemocyte count (THC), haemolymph norepinephrine (NE) level, caspase-3 mRNA expression and activity levels, and apoptotic haemocyte rate were measured when shrimp Litopenaeus vannamei (20-25 g) were transferred from 28 to 22 degrees C after 0, 2, and 7 days, and the caspase-3 mRNA expression and activity levels and the apoptotic cell rate of haemocytes, in vitro, were determined after incubation with 2 x 10(-8) M NE for 0, 30, 60, and 120 min at 27 +/- 1.0 degrees C. For shrimp transferred from 28 +/- 1.0 to 22 +/- 0.5 degrees C after 2 and 7 days, the THC decreased by 17.9% and 18.0%, but the NE concentration, caspase-3 transcription and activity levels, and apoptotic cell rate increased by 62.5% and 37.3%, 5100.0% and 446.6%, 148.6% and 152.0%, and 88.7% and 200.1%, respectively, compared to those of shrimp held at 28 +/- 0.5 degrees C which served as the control. Similar tendencies were observed for the apoptotic cell rate, and caspase-3 transcription and activity levels of haemocytes exposed to 2 x 10(-8) M NE in vitro. These results suggest that NE plays an important role in the apoptosis of haemocytes in L. vannamei under hypothermal stress, which causes depressive effects on immunological responses.

Expression of clottable protein of tiger shrimp (Penaeus monodon) in gonads and its possible role as nutrient source for the embryo.

We have investigated the expression of clottable protein (CP) in gonad of tiger shrimp (Penaeus monodon) and extent of its phosphorylation. Polyclonal antibodies against purified CP were prepared from rabbit serum. Using this anti-CP antiserum, the temporal expression of CP in gonads of tiger shrimp was analyzed. It was found that the CP occurs only in mature ovaries but not in immature ovaries and testes. Results of RT-PCR confirmed that these tissues expressed low levels of CP mRNA transcripts. Upon eyestalk-ablation, the ovaries in female shrimps were induced to develop, and the CP expression levels in ovaries were traced chronically by RT-PCR analyses. The expression level peaked on day 3 with an increase of about 40 folds relative to the basal level and returned to normal level (as the control shrimp) at day 12. The shrimp embryos at different intervals from spawning to 16h post-spawning were also collected, and it was found that CP contents were gradually decreased in the embryos until the nauplii were hatched. In addition, purified CP was shown to react with specific anti-phosphoserine, anti-phosphothreonine, and anti-phosphotyrosine antibodies suggesting that CP is a phosphoprotein with all types of phosphorylations. Taken together the results suggest that expression of CP in shrimp ovaries is coupled to ovarian development and CP possibly supply nutrition for shrimp embryo.