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The distributions of D-amino acid oxidase (D-AAO, EC 1.4.3.3) and D-aspartate oxidase (D-AspO, EC 1.4.3.1) activities were examined on several tissues of various fish species. Both enzyme activities were commonly high in kidney and liver and low in intestine with some exceptions. After oral administration of D-alanine at 5 micromol /g body weight(-1)day(-1) to carp for 30 days, D-AAO activity increased by about 8-, 3-, and 1.5-fold in intestine, hepatopancreas, and kidney, respectively, whereas no increase was found in brain. In contrast, oral administration of D-glutamate or D-aspartate did not show any increase of D-AspO activity in any tissues. D-AAO and D-AspO of common carp kidney and hepatopancreas were subcellularly localized in peroxisomes, as clarified in mammals. D-proline was the best substrate for D-AAO in rainbow trout kidney, common carp kidney, and hepatopancreas, followed by D-alanine and D-phenylalanine. N-methyl-D-aspartate was the best substrate for D-AspO in rainbow trout kidney and common carp hepatopancreas. The optimal pH for D-AAO in rainbow trout kidney was broad, from 7.4 to 8.2, and that for D-AspO was around 10. D-AAO was inhibited by benzoate known as D-AAO inhibitor and D-AspO was strongly inhibited by meso-tartarate as D-AspO inhibitor. From these results, at least D-AAO in fish is considered to work as a metabolizing agent of exogenous and endogenous free D-alanine that is abundant in aquatic invertebrates such as crustaceans and bivalve mollusks, which are potential food sources of these fishes.

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Recently mud crab (Scylla olivacea) has emerged as a potential export commodity. Its farming is increasing rapidly in Bangladesh because of its lucrative price and high demand in international market. However, the farming or fattening of mud crab is totally dependent on capture of wild crablets. A huge quantity of mud crabs is being caught indiscriminately from nature and thus putting intense pressure on its wild stock, which is a major concern of conservation. Imposing ban at peak breeding season and setting a legal capture size are considered effective management tools for safe migration and spawning of berried females. There is contradictory information on breeding season of mud crab in Bangladesh. Thus, it is crucial to identify the peak breeding season of it and to formulate conservation policies to protect the berried crabs. Live crabs were collected year-round from the river adjacent to southwest part of Sundarbans. Although mud crab breeds throughout the year, March-April was identified as the peak breeding season of it. The second peak was observed in August-September. The highest abundance of crablets (1-2 months age) was recorded in May-June, and the lowest in January-February. Immature crablets were found all through the year that proves that mud crab is a continuous breeder. The highest amount of GSI value (11.6) was observed in February-March, which indicates that the breeding is very near. The size at first maturity (M 50 ) was estimated as 95.5 mm CW which lied at size class 91-100 mm (CW). The findings from the study will assist in fixing up the banning time and thus protecting the mother crabs; and will assist in formulating police to conserve and protect juvenile crabs in the sense that the minimum legal capture size of crabs will allow the adults to mate and spawn at least once before their capture.

The biochemical composition (proteins, lipid, ash and moisture) of different parts of the body (gill, meat, egg) of fattened and natural mud crab Scylla serrata was determined. Twenty four samples of S. serrata (12 from wild & 12 from fattening farm) of different sizes and sexes (half of the sample is male) were used in this study. The mean protein and lipid contents are significantly (p<0.05) higher in fattened crabs than natural in natural crabs regardless of size and sexes. Moisture and ash were higher in natural crab than in fattened ones. The highest and lowest moisture content was noticed in gills and eggs in both natural and fattened crabs. Protein and lipid contents were comparatively higher in eggs than in other body parts. Female crabs contained high protein and lipid than males in both natural and fattened crabs. From the results of this study it may considered that fattened crab might be comparatively superior to natural crabs as they appear to provide higher levels of protein and fat for human nutrition.

The amount of phenolics, flavonoids, and anthocyanins in ethanol extracts and antioxidant activity of both ethanol and lipophilic extracts of common fruity vegetables in Bangladesh were studied. Among the ethanol extracts of 15 fruity vegetables, M. oleifera had the highest total polyphenol content (85.05 mg gallic acid equivalent/g extract) followed by L. acutangula (61.74 mg gallic acid equivalent/g extract) and A. esculentus (48.92 mg gallic acid equivalent/g extract). L. acutangula had high a content of flavonoids (14.46 mg (+)catechin equivalent/g extract), which was almost similar to L. siceraria (13.67 mg catechin equivalent/g extract) followed by A. esculentus (11.95 mg catechin equivalent/g extract) and S. melongena (11.42 mg catechin equivalent/g extract). Highest anthocyanins content was in F. hispida (2.22 µmol/g extract) followed by S. melongena (1.04 µmol/g extract). Ethanol extracts of A. esculentus, F. hispida, L. acutangula, L. siceraria, and S. melongena exhib-ited high DPPH free radical scavenging activity with IC 50 of 70.4, 64.9, 70.4, 64.9, and 94.3 µg/mL respectively, whereas for the same lipophilic extracts of F. hispida and S. melongena showed lowest (37 µg/mL) IC 50 followed by M. oleifera (47.6 µg/mL), L. siceraria (57.5 µg/mL), and A. esculentus (63.3 µg/mL). These vegetables also showed high reducing powers, NO scavenging and total antioxidant capacity. Therefore, the top five potential fruity vegetables consist of both hydrophilic and lipophilic antioxidant(s), the order being F. hispida > M. oleifera > A. esculentus, L. acutangula > L. siceraria > and S. melongena.

Taxonomy of mud crabs genus Scylla has been misidentified for several years due to their high morphological plasticity. Several reports concerning mud crab have been published with misleading identification in Bangladesh. In this study, partial fragments of nuclear and mitochondrial DNA of Scylla species obtained from four locations along the Bangladesh coast were used to resolve taxonomical ambiguity of mud crab species. A single PCR product from the nuclear first internal transcribed spacer (ITS-1) marker and phylogenetic trees constructed based on 16S rDNA sequences indicated that all Scylla species obtained in this study were S. olivacea. Both molecular data and morphological characters revealed that S. olivacea is the only major species in Bangladesh coastal waters. Further, the 16S rDNA haplotypes significantly differed with known S. serrata by 33%. From this study it is clear that 'S. serrata' commonly reported from Bangladesh should be S. olivacea.