M. Aminur Rahman

Tilapia Lake Virus (TiLV) is a disease that affects tilapia fish, causing a high rate of sudden death at any stage of their growth. Unfortunately, there are currently no effective antiviral drugs or vaccines to control the progression of this disease. Researchers have discovered that the CRM1 protein plays a critical function in the development and spreading of animal viruses. By inhibiting CRM1, the virus’s spread in commercial fish farms can be suppressed. With this in mind, this study intended to identify potential antiviral drugs from two different tropical mangrove plants from tropical regions: Heritiera fomes and Ceriops candolleana . To identify promising compounds that target the CRM1 protein, a computer-aided drug discovery approach is employed containing molecular docking, ADME (absorption, distribution, metabolism and excretion) analysis, toxicity assessment as well as molecular dynamics (MD) simulation. To estimate binding affinities of all phytochemicals, molecular docking is used and the top three candidate compounds with the highest docking scores were selected, which are CID107876 (-8.3), CID12795736 (-8.2), and CID12303662 (-7.9). We also evaluated the ADME and toxicity properties of these compounds. Finally, molecular dynamics simulation was conducted to analyze the stability of the protein-ligand complex structures and confirm the suitability of these compounds. The computational study demonstrated that the phytochemicals found in H. fomes and C. candolleana could potentially serve as important inhibitors of TiLV, offering practical utility. However, further in vivo investigations are necessary to investigate the effectiveness of these compounds as antiviral drugs against the virus TiLV.

A field study was carried out to investigate the livelihood patterns the socio-economic conditions of the small-scale traditional fishermen of Kharingcha baor at Chaugachha upazilla in Jashore, Bangladesh. The survey was conducted on 100 peoples from 70 families of the fishermen in the study area. It was found from the study that 94% fishermen were comprising of males, while 6% were of females. Among them, the majority was Hindus (88%) and the minority was Muslims (12%). During the suvey, the proportion of semi paka houses were documented to be 88%, while kancha were 12%, and all the families had electricity facilities. It was found that 20% of fishermen had no education, 6% had passed SSC-HSC examinations, 14% had passed 6-10 classes and 24% had passed 1-5 classes. It revealed that 84% of fishermen were married and 16% were unmarried. Throughout the study, 33% of the fishermen were found to be dependent on village doctors, 40% on upazilla hospital and 27% on MBBS doctors. Several types of local boats and dingi nouka as well as nets such as tana jal (surrounding net), set bagnet, khapla jal (cast net), thela jal (push net) etc. were used for the harvesting of different fish species (Labeo rohita, Catla catla, Cyprinus carpio, Cirrhinus mrigala, Heteropneustes fossilis, Channa striatus, C. punctatus etc.). Averagely, 35-80 kg fish per day was caught by a group of fishermen using a boat. The majority of the fishers sold their harvested fishes upon the fulfillment of their demands. The monthly mean income of fishermen was around BDT. 5,000-15,000 in the baor area. Among the fishermen, 56% of them were observed to lend money from money lenders and 44% from the NGOs for their fishing-related activities and livelihoods. It revealed from the present findings that the traditional fishermen of Kharingcha baor require more technical, organizational and institutional helps for the improvement of their socioeconomic condition and sustainable livelihood.

Four recently-diverged species of Indo-Pacific sea urchins, belonging to the genus Echinometra, occur most abundantly and sympatrically along the coast of Okinawa Island, southern Japan. Among them, the two most distinct species—Echinometra sp. A (Ea) and Echinometra mathaei (Blainville, 1825) (Em)—were examined for potential hybridization through a series of cross-fertilization and hybrid raising experiments. Compared to conspecific crosses, fertilization rates in both heterospecific crosses were very low, even at a very high concentration of sperm. At limited sperm concentration, where conspecific crosses achieved near 100% fertilization, heterospecific crosses had <3% fertilization success. This strong block to fertilization in either heterospecific cross indicates the presence of a protein-binding system for gamete recognition. A significantly lower survival rate in larvae, juveniles, and adults does indicate a postzygotic isolating mechanism that is strong enough to limit hybrid survival, but is not complete, and did in fact cause some amount of developmental incompatibility or hybrid inviability. In adults, Em (ova) × Ea (sperm) was largest in live weight, followed by Ea (ova) × Em (sperm), Ea × Ea, and Em × Em, in that order. Other growth performances, such as test sizes, gonad weight, and gonad index of hybrids and their conspecifics, also followed the same trend as live weight. Phenotypic color patterns of the hybrids were maternally inherited, while other characters (spine length, morphology of tubefoot and gonad spicules, pedicellaria valve length, and gamete sizes) were intermediate. Ova and sperm of the F1 hybrids were fertile in backcrosses, minimizing the possibility that hybrid infertility is a postzygotic isolating mechanism. Nevertheless, intensive surveys failed to find individuals with such hybrid characteristics, suggesting a very low presence or complete absence of natural hybrids in the field. This strongly suggests that pre- and postzygotic isolating mechanism(s) are isolating these species. Among these mechanisms, strong gametic incompatibility and probably microhabitat separation, differences in spawning times, gamete competition, or other factors appear to be important for maintaining genetic integrity of these two species.

The present study investigates the geo-morphological features, hydro-biological profiles and resource characteristics of some selected wetlands in Brahmanbaria district, Bangladesh. Two categories of wetland have been classified on the basis of area such as the small category (40–100 ha), which belongs to 11 wetlands and the large category (100–200 ha) to nine wetlands. The mean depth of all the surveyed wetland does not exceed 3.29 ± 0.83 m. The mean value of organic matter was measured as 7.5 ± 6.34%. The maximum organic matter was recorded at Gagotia beel (24.60%) and the minimum organic matter was recorded at Kajolia beel (2.06%). The mean value of organic carbon was measured as 3.93 ± 3.33%. The highest amount of organic carbon was found at Gagotia beel (12.95%) while the lowest amount of organic carbon was observed at kajolia beel (1.08%). Soil texture indicates the percentage composition of sand, silt and clay in sediment. The average concentration of sand, silt and clay was recorded to be 53.31 ± 15.32, 17.61 ± 9.56 and 29.08 ± 12.87%, respectively. Among the 20 selected wetlands examined, 13 were found to be perennial wetlands where water is available throughout the year. There was significant difference among different wetlands in terms of organic carbon, organic matter, sand, silt and clay (P < 0.05) as analyzed by One Way Analysis of Variance (SPSS v.22). The sampling stations were presented as a map created by GIS (ArcMap v.10.1). This qualitative and quantitative assessment will not only provide new information about the geo-morphological and hydro-biological insights into the wetland but also will facilitate the development, management, and conservation of aquatic biodiversity in a significant and worthwhile manner.

The present study investigated the influence of different temperature levels (16, 19, 22, 25, 28, 31 and 34oC) on embryonic and early larval development of the tropical sea urchin, Tripneustes gratilla (Linnaeus, 1758) in a controlled laboratory condition. The critical lower and higher temperature for embryonic development was found to be 16 and 34oC, respectively. Embryos reared in these temperatures exhibited 100% abnormality within 48 h post-insemination. The time required to reach embryonic and larval stages was increased with temperature from 28oC followed by 31, 25, 22 and 19oC. The developmental time of 2-cell to 4-arm pluteus larvae showed significant (p<0.05) differences. The survival (%) of larvae at the prism, 2-arm and 4-arm stages were observed as dissimilar from 22 to 34oC, and the highest values (100% or near 100%) were found at 25 and 28oC. The morphometric measurements from prism to 4-arm pluteus larvae at different temperatures differed significantly (p<0.05). However among the temperatures evaluated, 28oC was found as the best temperature for better growth and development of larvae at all stages. The findings of the study would help to develop captive breeding and seed production programmes for commercial aquaculture of the species.

Sea cucumbers belonging to echinoderm are traditionally used as tonic food in China and other Asian countries. They produce abundant biologically active triterpene glycosides. More than 300 triterpene glycosides have been isolated and characterized from various species of sea cucumbers, which are classified as holostane and nonholostane depending on the presence or absence of a specific structural unit γ(18,20)-lactone in the aglycone. Triterpene glycosides contain a carbohydrate chain up to six monosaccharide units mainly consisting of d-xylose, 3-O-methy-d-xylose, d-glucose, 3-O-methyl-d-glucose, and d-quinovose. Cytotoxicity is the common biological property of triterpene glycosides isolated from sea cucumbers. Besides cytotoxicity, triterpene glycosides also exhibit antifungal, antiviral and hemolytic activities. This review updates and summarizes our understanding on diverse chemical structures of triterpene glycosides from various species of sea cucumbers and their important biological activities. Mechanisms of action and structural–activity relationships (SARs) of sea cucumber glycosides are also discussed briefly.

Sea urchin gonad is considered as a highly prized delicacy in several countries. It is also rich in valuable bioactive compounds including polyunsaturated fatty acids (PUFAs) and β-carotene. This study was undertaken to examine the antimicrobial properties of the ovary extract from sea urchin Diadema setosum against selected Gram-negative and Gram-positive bacteria. The ovary extract was obtained using two different solvents such as methanol and chloroform. The obtained extract was used to examine its potential antimicrobial properties against the following 11 bacterial species using the disc diffusion method: Gram-negative bacteria (Salmonella typhi, Salmonella typhimurium, Shigella flexneri, Pseudomonas aeruginosa, Aeromonas hydrophila, Acinetobacter sp, Citrobacter freundii and Klebsiella pneumonia) and Gram-positive bacteria (Bacillus subtilis, Staphylococcus epidermidis and Staphylococcus aureus). The activity was measured in terms of zone of inhibition (mm). The methanol extract exhibited a higher zone of inhibition against all the bacteria taken for examination. Whereas, the ovary extract obtained by chloroform did not show any antimicrobial activity against S. typhi, S. epidermidis, C. freundii and K. pneumonia. The results indicated that the ovary extract obtained by methanol extracts are capable of inhibiting the growth of pathogenic microbes taken for analysis. Moreover, the result indicates the presence of antimicrobial agents in sea urchin ovary. The study suggests that the ovary extract of D. setosum may be a potential source of antimicrobial agent for pathogenic microorganisms.

The Giant River Catfish Sperata seenghala, locally known as “Guizza Air” (and hereafter referred to as just Guizza), has significant aquacultural and conservational values, but closer monitoring of the fish is now badly needed. To protect the species from extinction, an experiment was undertaken to breed and produce seed of Guizza in a captive‐rearing system. In our study, Guizza were successfully bred and the naturally produced fry were reared at different stocking densities in nine earthen nursery ponds having an area of 0.012 ha each with an average depth of 0.8 m. Three stocking densities were evaluated in three replicates each. Fry produced from natural propagation that were stocked at 100,000/ha were defined as treatment 1 (T₁), those stocked at 150,000/ha as treatment 2 (T₂), and those stocked at 200,000/ha as treatment 3 (T₃). At stocking, all reared fry were of the same age‐group with a mean±SD length and weight of 1.74±0.27 cm and 0.20±0.03 g, respectively. Fry in all the experimental ponds were reared with commercial Saudi Bangla (SABINCO) nursery feed (32.06% crude protein) for the first 14 d and starter‐I (31.53% crude protein) for days 15–56. Growth (final weight, final length, weight gain, length gain, and specific growth rate) and survival of the fingerlings were significantly higher in T₁ than in T₂ and T₃. Feed conversion rate was significantly lower in T₁ than in T₂ and T₃. Moreover, the physicochemical measurements and plankton population of the pond water were within the optimal level for fish culture, with plankton abundance being higher in T₁ than in T₂ and T₃. Consistently higher net benefits were obtained from T₁ than from T₂ and T₃. Hence, of the three stocking densities, 100,000 fry/ha was the most suitable density for rearing Guizza fingerlings in nursery ponds.

We report here, the effects of extended competency on larval survival, metamorphosis, and postlarval juvenile growth of four closely related species of tropical sea urchins,Echinometrasp. A (Ea),E. mathaei(Em),Echinometrasp. C (Ec), andE. oblonga(Eo). Planktotrophic larvae of all four species fed on cultured phytoplankton (Chaetoceros gracilis) attained metamorphic competence within 22–24 days after fertilization. Competent larvae were forced to delay metamorphosis for up to 5 months by preventing them from settling in culture bottles with continuous stirring on a set of 10 rpm rotating rollers and larval survival per monthly intervals was recorded. Larval survival was highest at 24 days, when competence was attained (0 delayed period), and there were no significant differences among the four species. Larvae that had experienced a prolonged delay had reduced survival rate, metamorphosis success, and juvenile survival, but among older larvae, Em had the highest success followed by Ea, Eo, and Ec. Juveniles from larvae of all four species that metamorphosed soon after becoming competent tended to have higher growth rates (test diameter and length of spines) than juveniles from larvae that metamorphosed after a prolonged period of competence with progressively slower growth the longer the prolonged period. Despite the adverse effects of delaying metamorphosis on growth parameters, competent larvae of all four species were able to survive up to 5 months and after metamorphosis grew into 1-month-old juveniles in lab condition. Overall, delayed larvae of Em showed significantly higher larval survival, metamorphosis, and juvenile survival than Ea and Eo, while Ec showed the lowest values in these performances. Em has the most widespread distribution of these species ranging from Africa to Hawaii, while Ec probably has the most restricted distribution. Consequently, differences in distribution may be related to differences in the ability to delay metamorphosis.