Effects of Salinity Fluctuation Frequency on the Osmolarity,Na^+-K^+-ATPase Activity and HSP70 Expression in Juvenile Chinese Shrimp,Fenneropenaeus chinensis

Experiments were conducted to examine the effects of salinity fluctuation frequency on the osmolarity, Na^＋-K^＋-ATPase activity and HSP70 of Chinese shrimp Fenneropenaeus chinensis ruth initial wet body weight of 1.460g±0.091 g. The salinity in the control group （DO） was 28 throughout the experiment, whereas treatments D2, D4, D6 and D8 were subjected to different salinity fluctuation frequencies of 2, 4, 6 and 8d, respectively. The salinity in treatments D2, D4, D6 and D8 was kept at 28 for 2, 4, 6 and 8d, respectively, decreased abruptly to salinity 24, lasted for another 2 d, and then was raised to its initial value 28. This was a complete salinity fluctuation cycle that afterwards repeated itself. After 32 days, the osmolarity in treatments D2, D4, D6 and D8 was significantly lower than that in treatment DO （P〈0.05）. There were significant differences in both muscle and eyestalks HSP70 expression among groups. The HSP70 expressions in muscle and eyestalks in group D4 were 61.4% and 57.0% higher, respectively, than that in the control group DO （P〈0.05）. There were, however, no significant differences in gill or hepatopancreas Na^＋-K^＋-ATPase activity between the treatments and the control.

Impact of Some Agronomic Practices on Paddy Field Soil Health Under Varied Ecological Conditions: II. Influence of Soil Temperature

A 21-d incubation experiment was conducted under controlled laboratory conditions to study the effects of elevated temperatures (10, 25, and 40 ℃) on some microbiological and biochemical properties in flooded paddy soil amended or unamended with urea at 100 μg N g-1 soil and/or insecticide (triazophos) at field rate (FR). Enhancements in temperature led to increase the electron transport system (ETS) / dehydrogenase activity and phospholipid contents of the soil, while soil organic matter phenol and protein contents decreased with increasing temperature with or without the addition of inputs. An increase of temperature from 10 ℃ to 25 or 40 ℃ enhanced the ETS activity 2 folds (on average for all soils), while the inclusion of N and insecticide increased and decreased it, respectively, compared to the control. The soil phenol and protein contents were highly correlated with temperatures (for all soils, r = -0.936 and -0.971, respectively) and the additions of N and insecticide produced slight reductions and enhancements in them, respectively. At a particular temperature, the soil protein contents remained unaffected among all the soil treatments. An overall slight increase in phospholipid contents with N and a small decline with insecticide addition were noticed against the untreated soil. The toxicity of fertilizer and insecticide decreased as the incubation temperature increased, suggesting faster degradation of agrochemicals with raising temperature.

EFFECTS OF CALDESMON, CALPONIN, AND TROPOMYOSIN ON THE MG^(2+)-ATPase ACTIVITIES OF SMOOTH MUSCLE MYOSIN

Objective To test whether in the absence of actin, actin-binding proteins such as caldesmon, calponin, and tropomyosin interact with the myosin of unphosphorylation, Ca 2+ -dependent phosphorylation (CDP), and Ca 2+ -independent phosphorylati-on (CIP) and stimulate myosin Mg 2+ -ATPase activities. Methods Mg 2+ -ATPase activities were measured to evaluate the effects of caldesmon, calponin, and tropomyosin on the myosin in unphosphorylation, CDP by myosin light chain kinase (MLCK), and CIP by MLCK. Results (1) At different incubation-time, i.e., 5, 10, 20, 40, and 60 minutes, the highest Mg 2+ -ATPase activity was ob-served when myosin was in the state of CDP, the medium was CIP of myosin, and the lowest was the unphosphorylated myosin. (2) In the absence of caldesmon, calponin, and tropomyosin, the Mg 2+ -ATPase activities from high to low were in the following order: CDP, CIP, and unphosphorylated myosin. However, in the presence of caldesmon, calponin, and tropo-myosin, the order of relative value of Mg 2+ -ATPase activities from high to low was unphosphorylated, CIP, and CDP of myosin respectively compared to the corresponding controls. Conclusions The results propose that caldesmon, calponin, and tropomyosin are capable of stimulating Mg 2+ -ATPase activity of smooth muscle myosin in Ca 2+ -independent manner, since Ca 2+ is not obligating for the stimulating effects of the three proteins. The common characteristic of the three proteins is that when myosin activities are low, their activations are relatively strong and this property might be involved in smooth muscle tension keeping.

Studies on the Effects of Polyaspartate Protease Fertilizer Enhancer in the Absorptions of Soil Nutrition and the Enzymatic Activities of Crops

The effects of polyaspartate protease fertilizer enhancer, made from oyster shell proteins, on the absorption of soil nutrition and the enzymatic activities of crops were studied. It has been found that the enhancer contributes 30%, 50% and 50% augmentation of nitrogen (N), phosphate (P) and potassium (K) absorption respectively and about 20% of nitrate reductase and peroxide enzyme activities of crops. These results show that polyaspartate protease fertilizer enhancer could improve significantly the absorption and utilization efficiencies of soil nutrition and the activities of nitrate reductase and peroxide enzyme of crops, thus elevating the utilization rates of chemical fertilizers to a certain extent.

Mechanical Stress Induces Neuroendocrine and Immune Responses of Sea Cucumber(Apostichopus japonicus)

Grading procedure in routine sea cucumber hatchery production is thought to affect juvenile sea cucumber immunologi- cal response. The present study investigated the impact of a 3-min mechanical perturbation mimicking the grading procedure on neuroendocrine and immune parameters of the sea cucumber Apostichopusjaponicus. During the application of stress, concentrations of noradrenaline and dopamine in coelomic fluid increased significantly, indicating that the mechanical perturbation resulted in a transient state of stress in sea cucumbers. Coelomocytes concentration in coelomic fluid increased transiently after the beginning of stressing, and reached the maximum in 1 h. Whereas, coelomocytes phagocytosis at 3 min, superoxide anion production from 3 min to 0.5 h, acid phosphatase activity at 0.5 h, and phenoloxidase activity from 3 min to 0.5 h were all significantly down-regulated. All of the immune parameters recovered to baseline levels after the experiment was conducted for 8 h, and an immunostimulation occurred after the stress considering the phagocytosis and acid phosphatase activity. The results suggested that, as in other marine invertebrates, neuroendocrine/immnne connections exist in sea cucumber A. japonicus. Mechanical stress can elicit a profound influence on sea cucumber neuroendocrine system. Neuroendocrine messengers act in turn to modulate the immunity fimctions. Therefore, these ef- fects should be considered for developing better husbandry procedures.