http://nopr.niscair.res.in/handle/123456789/1490 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/1505 Title: Effect of temperature and body size on food utilization in the marine pearl oyster Pinctada fucata (Bivalvia: Pteridae) <br/> <br/>Authors: Mondal, Sandip Kumar <br/> <br/>Abstract: Physiological parameters such as clearance rates, absorption efficiency, oxygen consumption and ammonia excretion were estimated for four size groups ranging from 16 to 60 mm in Dorso Ventral Measurements (DVM) of the marine pearl oyster Pinctada fucata at different water temperatures and the results were integrated by means of two physiological indices, namely Scope For Growth (SFG) and Net Growth Efficiency (K2). The rates of clearance, oxygen consumption and ammonia excretion were found strongly correlated (p ≤ 0.01) with size groups (as tissue dry weight) at water temperature from 18o to 31ºC. Absorption efficiency ranged from 43.2 to 56.9 % and was not related to body size in the tested temperature range. Oxygen consumption and ammonia excretion increased with temperature within the same size group from 18º to 31ºC. Clearance rate increased with temperature from 18º to 28ºC, but declined with further increase of temperature to 31ºC. Excreted energy contributed 2.4 to 4.0% to the total absorbed energy for different size groups and water temperatures. The SFG and K2 were higher at 26º and 28ºC and were minimum at 18ºC for all the size groups. The result showed that the optimum physiological conditions for survival and growth of P. fucata were in the temperature range of 26º to 28ºC. <br/> <br/>Page(s): 43-49 http://nopr.niscair.res.in/handle/123456789/1504 Title: Microbial diversity and enzyme production in mullet Mugil cephalus L. (Pisces) along Goa, west coast of India <br/> <br/>Authors: Nagvenkar, G.S.; Nagvenkar, S.S.; Rivonker, C.U.; Sangodkar, U.M.X. <br/> <br/>Abstract: Twelve bacterial species were isolated from different organs of the mullets. A comparative analysis of different bacterial communities isolated from surface, gills and intestinal tract showed significantly diverse population with reference to different groups and density. During present investigations, some of the important microbial groups occurred in the different regions of the Mugil cephalus were Pseudomonas sp., Vibrio parahaemolyticus, Serratia sp., Azotobacter sp., Streptococcus sp., Proteus vulgaris, Planococcus sp., Bacillus subtilis and Serratia marescens. Further study on production of enzyme in the gut content suggested that proteolytic and amylolytic activity were of elevated level, thus emphasizing that these microbial communities do play an important role in promoting efficient food utilization among mullets. <br/> <br/>Page(s): 36-42 http://nopr.niscair.res.in/handle/123456789/1503 Title: Is gender a factor contributing to the variations in the concentrations of heavy metals (Cd, Cu, Pb and Zn) by the green-lipped mussel Perna viridis ? <br/> <br/>Authors: Yap, C. K.; Ismail, A.; Tan, S. G.; Ismail, A. Rahim <br/> <br/>Abstract: The concentrations of Cd, Cu, Pb and Zn were determined in mantles plus gills, gonads and the remaining soft tissues of males and females from a single population of the green-lipped mussel Perna viridis. In addition, the metal concentrations were determined in the total soft tissues of male and female mussels collected from 15 sampling sites in Malaysia. Females generally accumulated higher concentrations of metals than the males but the difference was not significant (P> 0.05). The correlation coefficients showed higher R-values in the females than in the males. Although the differences in the metal concentrations of the tissues were not significant (P> 0.05), gender was still an important factor in contributing to the variations of concentrations of Cu, Pb and Zn in the soft tissues of P. viridis as was shown by multiple stepwise regression analysis. <br/> <br/>Page(s): 29-35 http://nopr.niscair.res.in/handle/123456789/1502 Title: Cryopreservation of the sperm of spotted halibut Verasper variegates (Pleuronectiformes, Pleuronectidae) <br/> <br/>Authors: Liu, Xuezhou; Zhang, Shicui; Zhang, Yongzhong; Xu, Yongjiang <br/> <br/>Abstract: The sperm of spotted halibut Verasper variegates was cryopreserved by a simple and convenient protocol. The cryoprotectants used were dimethyl sulfoxide (Me₂SO), glycerol (Gly), methanol (MeOH), Me₂SO + egg yolk, Gly + egg yolk and MeOH + egg yolk. The percentage of forward motile sperm in semen cryopreserved in the different extenders with Me₂SO, Gly, MeOH, Me₂SO + egg yolk, Gly + egg yolk and MeOH + egg yolk was 40.5 ± 4.2%, 49.5 ± 4.2%, 38.3 ± 2.4%, 65.0 ± 4.0%, 67.5 ± 2.9% and 49.5 ± 8.4%, respectively. The fertilization and hatching rates of cryopreserved sperm were from 59 ± 2.4% to 70 ± 3.0%, and from 11 ± 3.0% to 18 ± 2.6%, respectively. These tended to be highest when Gly + egg yolk or Me₂SO + egg yolk were used as cryoprotectants. Under SEM, it could be seen that while the majority of the freeze-thawed sperm remained morphologically normal, some exhibited damaged or lost mitochondria, which possibly caused the decrease in motility and fertility of the freeze-thawed sperm <br/> <br/>Page(s): 24-28