a b s t r a c tThe Hsp70 class of heat shock proteins (Hsps) has been implicated at multiple points in the immune response of both vertebrates and invertebrates. This class of chaperones is highly conserved in both sequence and structure, from prokaryotes to higher eukaryotes. In view of their high degree of homology, it was assumed that these Hsp70 proteins derived either from the prokaryotes or eukaryotes would have similar functions, especially in relation to their protective ability in a challenge assay. To verify this, we compared two evolutionary diverse Hsp70s, Artemia Hsp70 and Escherichia coli Hsp70 equivalent DnaK (each overproduced in E.coli), for their ability to protect Artemia against Vibrio challenge. Results showed that Artemia fed with E. coli producing Artemia Hsp70 or DnaK proteins, as assessed by immune-probing in western blots, survived better in a Vibrio challenge assay. The observed effects could be due to enhancement of the Artemia immune system as phenoloxidase activity was found to be increased by these proteins. These two Hsp70 proteins exhibit a high degree of homology, particularly in the peptidebinding domain (the putative innate immunity-activating portion) with 59.6% identity, indicating that the observed protective capacity of homologous or heterologous Hsp70 proteins might reside within this peptide-binding domain.

The proximate composition of the whole body and the fatty acid composition of the liver, muscle, eye and brain of wild and cultured rohu (Labeo rohita) were analyzed. The cultured species was found to have significantly (P < 0.05) higher lipid contents than its wild counterpart. The saturated (SFA) and monounsaturated (MUFA) fatty acid contents were significantly higher in the cultured species, whereas the n-6 and n-3 polyunsaturated fatty acid (PUFA) levels were higher in the wild species. Fatty acids C16:0 and C18:1 n-9 were the principal fatty acids of the SFAs and MUFAs, respectively, identified in the analyses. Docosahexaenoic acid, eicosapentaenoic acid, and arachidonic acid were the predominant PUFAs in both groups, and all three were found to be present at significantly (P < 0.05) higher levels in the wild species. Erucic acid (C22:1 n-9), which was the predominant fatty acid (30.76%) in the feed, was detected only at low levels in muscle (0.30%), liver (1.04%) and eye (1.28%) of cultured fish tissue.

A 60-day experiment was conducted to study the effect of dietary gelatinized (G) and non-gelatinized (NG) starch on the key metabolic enzymes of glycolysis (hexokinase, glucokinase, pyruvate kinase, and lactate dehydrogenase), gluconeogenesis (glucose-6 phosphatase and fructose-1,6 bisphosphatase), protein metabolism (aspartate amino transferase and alanine amino transferase), and TCA cycle (malate dehydrogenase) in Labeo rohita juveniles. In the analysis, 234 juveniles (2.53 +/- 0.04 g) were randomly distributed into six treatment groups each with three replicates. Six semi-purified diets containing NG and G cornstarch, each at six levels of inclusion (0, 20, 40, 60, 80, and 100) were prepared viz., T1 (100% NG, 0% G starch), T2 (80% NG, 20% G starch), T3 (60% NG, 40% G starch), T4 (40% NG, 60% G starch), T5 (20% NG, 80% G starch), and T6 (0% NG, 100% G starch). Dietary G:NG starch ratio had a significant (P < 0.05) effect on the glycolytic enzymes, the highest activities were observed in the T6 group and lowest in the T1 group. On the contrary, the gluconeogenic enzymes, the glucose-6-phosphatase and fructose-1,6 bisphosphatase activities in the organs, liver and kidney were recorded highest in the T1 group and lowest in the T6 group. The liver aspartate amino transferase activity showed an increasing trend with the decrease in the dietary G level. However, the muscle aspartate amino transferase activity was not significantly (P > 0.05) influenced by the type of dietary starch. The alanine amino transferase activity in both liver and muscle showed an increasing trend with the decrease in the dietary G level. The liver and muscle malate dehydrogenase activities were lowest in the T6 group and highest in the T1 group. Results suggest that NG (100%) starch diet significantly induced more the enzyme activities of amino acid metabolism, gluconeogenesis, and TCA cycle, whereas partial or total replacement of raw starch by gelatinized starch increased the glycolytic enzyme activity.

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White spot syndrome virus (WSSV), the sole member of the monotypic family Nimaviridae, is considered an extremely lethal shrimp pathogen. Despite its impact, some essential biological characteristics related to WSSV genome dynamics, such as the synonymous codon usage pattern and selection pressure in genes, remain to be elucidated. The results show that compositional limitations and mutational pressure determine the codon usage bias and base composition in WSSV. Furthermore, different forces of selective pressure are acting across various regions of the WSSV genome. Finally, this study points out the possible occurrence of two major recombination events.

A 60‐d feeding trial was conducted to study the effect of dietary gelatinized (G) and nongelatinized (NG) starch on deposition of nucleic acid in liver and muscle of Labeo rohita juveniles. Two hundred and thirty‐four juveniles (av. wt. 2.53 ± 0.04 g) were randomly distributed into six triplicate experimental groups. Six semipurified diets containing graded levels of (0, 20, 40, 60, 80, 100) NG and G corn starch, were prepared accordingly: T1 (100% NG, 0% G); T2 (80% NG, 20% G); T3 (60% NG, 40% G); T4 (40% NG, 60% G); T5 (20% NG, 80% G); and T6 (0% NG, 100% G). After a feeding period of 60 d, DNA content in muscle and liver decreased linearly with increasing level of G starch in the diet, whereas protein/DNA in muscle increased linearly with increasing levels of G starch in the diet. No significant effect of G starch on RNA deposition in liver and muscle was found. RNA/DNA ratio increased linearly with increasing level of gelatinized starch in the diet. Results from this study indicate that protein/DNA and RNA/DNA ratio in muscle increase with increasing levels of G starch in the diet, which also reflects in terms of growth performance.