Effect of saccharomyces cerevisiae on survival, growth, biochemical constituents and energy utilization in the prawn macrobrachium rosenbergii.

A probiotic yeast, Saccharomyces cerevisiae was incorporated in basal diet prepared with fish meal, soybean meal, groundnut oil cake, corn flour, tapioca flour, egg albumin, cod liver oil and vitamin Bcomplex, at four different concentrations (10g, 20g, 30g and 40g kg-1) and fed to Macrobrachium rosenbergii post larvae (PL) for 90 days. The effect of this probiotic incorporation on the growth and survival performances, concentration of protein, amino acid, carbohydrate and lipid, and energy utilization was found to be significantly (P<0.05) higher at 40g kg-1 followed by 30g, 20g and 10g kg-1. 40g kg-1 S. cerevisiae incorporation was found to be established the highest rate of colony formation, 234x10-4 cfu (colony formation units). Actually, presence of Bacillus spp., Bacillus cereus, Pseudomonas spp., Escherichia coli, Streptococcus spp., and Klebsiella pneumoniae were deducted in water medium and the PL gut of control group. There is a general belief that Pseudomonas spp. and K. pneumonia are pathogenic to prawns. The establishment of S. cerevisiae colony in the gut of experimental PL has eradicated these pathogenic bacteria. Therefore, it is suggested that establishment of S. cerevisiae colony has led to better growth, survival and biochemical constituents in M. rosenbergii PL. Thus, S. cerevisiae could be taken as a useful probiotic in M. rosenbergii culture.

Growth of macrobrachium rosenbergii fed with mango seed kernel, banana peel and papaya peel incorporated feeds.

The growth promoting potential of fruits wastes, mango seed kernel, banana peel and papaya peel on the freshwater prawn, Macrobrachium rosenbergii post larvae (PL) was evaluated. Basal diet equated to 35% protein was prepared by using soybean meal, groundnut oilcake, horse gram and wheat flour. Each fruit waste powder was separately incorporated with basal diet at a proportion of 10%. Sunflower oil was used as lipid source. Egg albumin and tapioca flour were used as binding agents. Vitamin B-complex with Vitamin-C was also mixed. Feed without any fruit waste was served as control. M. rosenbergii PL (length: 1.2-1.4 cm; weight: 0.09- 0.13 g) was fed with these feeds for a period of 90 days. Significant improvements in the nutritional indices (survival rate, weight gain, biomass index, specific growth rate and condition factor), concentrations of biochemical constituents (total protein, carbohydrate and lipid), levels of non-enzymatic antioxidants (vitamin-C and E), content of minerals (Na+ and K+), activities of digestive enzymes (protease, amylase and lipase), and profiles of essential amino acids and fatty acids were recorded in fruits wastes incorporated feeds fed PL when compared with control (P< 0.003 – 0.878). The overall results indicated the fact that mango seed kernel incorporated feed was produced the best performance, followed by better performance of banana peel and good performance of papaya peel. These fruits wastes incorporated feeds enhance digestive enzymes activities and act as appetizer, which in turn enhances food utilization and ultimately yielded better survival and growth of M. rosenbergii PL. Therefore, these fruits wastes have considerable potentials in sustainable development of Macrobrachium culture.

Glutathione S-transferase and metallothionein levels in the freshwater prawn Macrobrachium malcolmsonii exposed to mercury.

Healthy juveniles of M. malcolmsonii were exposed to 24.1 <g l-1 of mercury (96 hr LC50: 145 <g l-1 Hg) for a period of 21 days. The hepatopancreas and gills of the prawns were sampled on 8th, 15th and 22nd day of exposure. Accumulation and elimination of Hg, activity of glutathione S-transferase (GST), content of glutathione (GSH) and metallothionein (MT) level were studied. Mercury accumulation was found to be higher in the hepatopancreas (88.60 <g g-1) and lower in the gills (67.8 <g g-1). However, Hg elimination was found to be faster in the gills (62%) and slower in the hepatopancreas (58%). Therefore, the rate of Hg elimination did not match the rate of its uptake. The activity of GST was found to be higher in tissues of test prawns (5.94-9.13 nmol mg-1 protein min-1) on all sampling days when compared with controls (3.45-4.23 nmol mg-1 protein min-1). Similarly, the content of GSH was found to be higher in tissues of test prawns (0.80-1.43 <mol g-1 protein) on all sampling days when compared with controls (0.55-1.00 <mol g-1 protein). These results indicate the formation of glutathione conjugate in test prawns to eliminate Hg. The induction of MT level was also found to be higher in tissues of test prawns (57.50-75.76 nmol g-1 protein) on all sampling days when compared with control (20.24-45.22 nmol g-1 protein). This indicates the fact that sequestration of Hg has occurred for its easy elimination. Thus, induction of GST-GSH and MT ensured protection and adaptation of test prawns to thrive in Hg contaminated environment.

Sub-lethal impact of carbaryl on food utilization in the freshwater prawn Macrobrachium malcolmsonii.

This study determines the toxic effect of carbaryl (Sevin® 50% W.P) on the food utilization parameters in intermoult juveniles of the prawn, Macrobrachium malcolmsonii. The prawns (4.5-5.0 cm in length and 1.0- 1.25 g wet wt.) were exposed to three sub-lethal concentrations of carbaryl (5.15, 7.73 and 15.47 μg l-1) for duration of 40 days. The toxic medium was renewed daily. The prawns were fed ad libitum with known energy quantity of boiled goat liver on daily basis. The overall wet weight gain was calculated. The energy lost through unconsumed food (15-60%), faeces (15-109%), ammonia excretion (9-27%) and moults (13-26%) of the prawns were calculated. The feeding rate, the rate and efficiency of absorption, the metabolic and food conversion rates and the gross and net food conversions efficiencies were found to be significantly declined (p<0.05) in test prawns when compared to that of the control. The energy lost through faeces, ammonia excretion and exuvia was found to be significantly elevated (p<0.05) in test prawns than that of the control. The effect of carbaryl on the bioenergetics parameters was severe in the highest sub-lethal concentration, less in the intermediate concentration and least in the lowest sub-lethal concentration. The results indicated that decrease in feeding, absorption, metabolism and food conversion are interdependent and toxicity of carbaryl diverting energy from production to maintenance pathways, which ultimately resulting in declined growth of M. malcolmsonii.

Ultrastructural observations in gills and hepatopancreas of prawn Macrobrachium malcolmsonii exposed to mercury.

The juveniles of M. malcolmsonii were exposed to 24.1 µg l-1 of Hg for a period of 21 days. The gills and hepatopancreas of test prawns were sampled and processed for electron microscopic observations. Mitochondria are the organelle most affected in the gills of test prawns. The number of mitochondria and the electron-density of the matrix were found to be less in test prawns. The in-folding of cell membrane associated with mitochondria was absent in test prawns. This suggests that operation of the mitochondrial pumps was affected in the gills of test prawns. Vacuoles with crystalline granular inclusions were noted in the gills of test prawns. These are suggestive of metal-rich inorganic deposits or granules representing detoxified dumps of Hg. In the hepatopancreas of test prawns, the tubules exhibit vacuoles with granular inclusion and the cell cytoplasm contains electron-dense granules, which indicate a storage detoxification of Hg. The mitochondria were shrunken in the hepatopancreas of test prawns. This suggests attenuation of its function. The rough endoplasmic reticulum appeared vesiculated and dilated. These reactions denote the hyperactivity of the rough endoplasmic reticulum. Membranous whorl-like structures with myelin fibers and residual bodies were seen in the hepatopancreas of test prawns. Such structures indicate the involvement of lysosomal breakdown in detoxification process. The ultrastructural alterations are suggestive of the operation of compensatory mechanisms within the test prawns to enable it to tolerate Hg toxicity. However, these alterations would have an impact on the cellular integrity of the gills and hepatopancreas and such alterations can be taken as ‘biomarkers’ for assessing Hg pollution in the aquatic environment.

Manifestation of carbaryl toxicity on soluble protein and histopathology in the hepatopancreas and gills of the prawn, Macrobrachium malcolmsonii.

The present study examined alterations in the protein pattern and histopathology of the hepatopancreas and gills of Macrobrachium malcolmsonii following exposure to Sevin®, the commercial grade of carbaryl (1-Naphthylmethyl carbamate) pesticide. Juvenile prawns were exposed to sub-lethal concentrations 5.15 'g l-1, 7.73 'g l -1and 15.47 'g l -1of carbaryl for 21 days. Samples were obtained from the hepatopancreas and gills of prawns. The concentration of buffer soluble protein in tissues of test prawns was significantly (p<2.5%) lower than the control. This suggests that proteins were utilized to generate energy in order to withstand carbaryl induced toxic stress. Polypeptide bands of different molecular mass (150 - 10 kDa) in tissues of test prawns stained less intensely than those in control. This indicates that carbaryl toxicity caused protein degradation in tissues of test prawns. The histology of the hepatopancreas and gills showed few marked pathological changes in prawns exposed to carbaryl. These include rupture of the basal laminae, abnormal infiltration / aggregation of hemocytes in the interstitial sinus of the hepatopancreas and in the hemocoelic space of gill lamellae, fused gill lamellae and necrosis like appearance both in the tubules of the hepatopancreas and gill lamellae. The structural alterations observed in the hepatopancreas and gills of the prawns suggest that carbaryl caused tissue damage in M. malcolmsonii. Protein degradation is a phenomenon in damaging tissues, and thus, under such condition the hepatopancreas and gills of test prawns would not perform their vital functions, which in turn ultimately affect the survival and growth of M. malcolmsonii. The changes noted in protein and histology of test prawns can be taken as biomarkers for monitoring pesticide pollution in aquatic environments. Since this species of prawn is a nutritious delicacy to human being, monitoring aquatic pollution by carbaryl is warranted.

Profiles of acid and alkaline phosphatases in the prawn Macrobrachium malcolmsonii exposed to endosulfan.

The present study was performed to determine the toxic effects of endosulfan on the quantitative and qualitative aspects of acid and alkaline phosphatases (ACP and ALP) in Macrobrachium malcolmsonii. Intermoult juvenile prawns were exposed to 32.0 ng/l of endosulfan for a period of 21 days. Samples were taken from the hemolymph, hepatopancreas, gills and muscle of test prawns on the 21st day. The content of ACP and ALP in the hepatopancreas of test prawns were found to be higher in comparison to respective controls. The levels of these enzymes in the hemolymph, gills and muscle of test prawns were found to be lower than in the same tissues of controls. In non-denaturing PAGE, phosphatases appeared as white bands. The intensity of white bands in the hepatopancreas of test prawns were found to be higher when compared to controls. In the hemolymph, gills and muscle of test prawns, the intensity of white bands were found to be lower in comparison to controls. The results of the present study suggest that endosulfan affects the quantity and quality of ACP and ALP in the tissues of M. malcolmsonii.

Carbaryl-induced alterations in biochemical metabolism of the prawn, Macrobrachium malcolmsonii.

The present study was performed to investigate the toxic impact of carbaryl on biochemical metabolism in the hemolymph, brain, hepatopancreas, gills and muscle of intermoult juveniles of the economically important prawn, Macrobrachium malcolmsonii. The concentration of glutathione S-transferase (GST) was found to be higher in test prawns when compared with controls. This suggests that a mechanism of detoxification was in operation to neutralise carbaryl toxicity. However, the toxic effect of carbaryl was not fully neutralised, and hence, alterations were recorded in basic biochemical metabolism of test prawns. The concentration of acetylcholinestrase (AchE) was found to be lower in test prawns than that of controls. Carbaryl toxicity resulted in utilisation of major biochemical constituents, such as total carbohydrate, glycogen, protein and lipid to generate required energy as an attempt to withstand the toxic stress. Glycogenolysis resulted in elevation of total free sugar level in the hemolymph of test prawns. While proteolysis led to elevation of total free amino acid level in test prawns. The content of total lipid have also been found lower in test prawns than that of controls. This suggests that carbaryl toxicity resulted in severe energy crises in test prawns. In the present study, toxic effects of carbaryl impair basic metabolic functions and hence pose a threat to the life of M. malcolmsonii.