Assessing the bioavailability of L‐methionine and a methionine hydroxy analogue (MHA‐Ca) compared to DL‐methionine in rainbow trout (Oncorhynchus mykiss)

Different synthetic forms of supplemental methionine (Met) are produced commercially by various manufacturers. Limited information exists on the bioavailability of these different forms in commercially relevant fish species. The objective of this study was to compare the relative bioavailability of L‐methionine and a methionine hydroxy analogue calcium salt (MHA‐Ca) to DL‐methionine in a commercially relevant species, rainbow trout, using a linear slope‐ratio assay. In addition, the ability of the rainbow trout to effectively convert the D‐isomer of methionine into the biologically active L‐isomer was studied by comparing the relative bioavailability of L‐methionine to DL‐methionine. Nine (9) diets were created from a methionine‐deficient basal diet which was supplemented with graded equimolar levels of methionine (0.1%, 0.2%, 0.3% of diet by weight) from either DL‐methionine, L‐methionine and methionine hydroxy analogue calcium salt (MHA‐Ca). Diets were fed in triplicate (IBW = 24.0 ± 0.6 g) for 12 weeks using a pair‐feeding protocol. The basal diet was formulated to be deficient in both methionine (0.5%) and cysteine (0.3%), whereas meeting all other known nutritional requirements of rainbow trout. MHA‐Ca was found to be less available (P < 0.05) than DL‐methionine with relative bioavailability values of 69%, 60% and 73% based upon weight gain, growth rate (TGC) and retained nitrogen values respectively. No significant differences (P > 0.05) in bioavailability were found between DL‐methionine and L‐methionine. These findings lead to the conclusion that differences in bioavailability do exist between sources of synthetic methionine, additionally findings suggest that rainbow trout are able to effectively convert the D‐isomer of methionine into the L‐isomer without significantly affecting fish performance.     

Dietary phytase and protease improved growth and nutrient utilization in tilapia (Oreochromis niloticus × Oreochromis aureus) fed low phosphorus and fishmeal‐free diets

A 10‐week study was conducted to evaluate the effects of supplemental phytase and protease in low phosphorus (LP) and fishmeal‐free diets (FMF) on growth and nutrient utilization of tilapia. Seven isonitrogenous diets were prepared as positive control diet (PC) containing 60 g/kg fishmeal and 18 g/kg monocalcium phosphate (MCP), LP diet (12 g/kg MCP), FMF diet, LP‐FMF diet, and three enzyme diets with phytase (LP + Ph), protease (FMF + Pr), and phytase + protease (LP‐FMF + Ph + Pr) supplementation in LP, FMF and LP‐FMF diets, respectively. Weight gain, nutrient (except Ca) retention and digestibility of LP, FMF and LP‐FMF groups were lower than those of PC group (p < 0.05). Compared to LP, FMF and LP‐FMF groups, the supplementation of phytase, protease and phytase + protease improved WG by 13.2%, 11.1% and 13.0% (p < 0.05). The three enzyme groups showed higher digestibility of protein and P, and higher intestinal villus length than those of LP, FMF and LP‐FMF groups (p < 0.05), respectively. Dietary phytase and Ph + Pr also promoted the retentions of crude protein and P (p < 0.05). The results indicated that the supplementation of phytase in LP diet and protease in FMF diet improved the growth and nutrient utilization, and phytase reduced MCP inclusion in the diet of tilapia.     

Farmers' perceptions of and responses to environmental change in southwest coastal Bangladesh

Coastal Bangladesh is highly vulnerable to climate change and salinisation; hence, farm‐level adaptation is critically important. Farmers' perceptions of and responses to environmental change were investigated in two villages in Khulna District. Perceived environmental trends included increases in temperature, extreme weather events, soil toxicity, erratic rainfall and scarcity of water for irrigation. Perceptions of climate trends were consistent with measured trends in Khulna. On‐farm adaptation strategies included adjusting planting dates, excavating trenches in rice‐fields, adopting new crops, salinity‐reducing technologies, livestock‐rearing and home‐yard cropping. Non‐farm adaptation strategies included wage employment, short‐term migration and self‐employment. Adaptation was facilitated by income‐earning opportunities, training, and credit, and impeded by lack of access to water, markets, capital, and extension services. Farmers suggested policy support for dissemination of stress‐tolerant cultivars, access to irrigation, and price stabilisation or crop insurance to assist adaptation. While the study shows an impressive degree of awareness and adaptation, external support is needed to increase adaptive capacity.     

Characterization of HOX gene expression in canine mammary tumour cell lines from spontaneous tumours

Spatial/temporal controls of development are regulated by the homeotic (HOX) gene complex and require integration with oncogenes and tumour suppressors regulating cell cycle exit. Spontaneously derived neoplastic canine mammary carcinoma cell models were investigated to determine if HOX expression profiles were associated with neoplasia as HOX genes promote neoplastic potential in human cancers. Comparative assessment of human and canine breast cancer expression profiles revealed remarkable similarity for all four paralogous HOX gene clusters and several unlinked HOX genes. Five canine HOX genes were overexpressed with expression profiles consistent with oncogene‐like character (HOXA1, HOXA13, HOXD4, HOXD9 and SIX1) and three HOX genes with underexpressed profiles (HOXA11, HOXC8 and HOXC9) were also identified as was an apparent nonsense mutation in HOXC6. This data, as well as a comparative analysis of similar data from human breast cancers suggested expression of selected HOX genes in canine mammary carcinoma could be contributing to the neoplastic phenotype.     

Antiproliferative and Antimicrobial Potentials of a Lectin from Aplysia kurodai (Sea Hare) Eggs

In recent years, there has been considerable interest in lectins from marine invertebrates. In this study, the biological activities of a lectin protein isolated from the eggs of Sea hare (Aplysia kurodai) were evaluated. The 40 kDa Aplysia kurodai egg lectin (or AKL-40) binds to D-galacturonic acid and D-galactose sugars similar to previously purified isotypes with various molecular weights (32/30 and 16 kDa). The N-terminal sequence of AKL-40 was similar to other sea hare egg lectins. The lectin was shown to be moderately toxic to brine shrimp nauplii, with an LC₅₀ value of 63.63 µg/mL. It agglutinated Ehrlich ascites carcinoma cells and reduced their growth, up to 58.3% in vivo when injected into Swiss albino mice at a rate of 2 mg/kg/day. The morphology of these cells apparently changed due to AKL-40, while the expression of apoptosis-related genes (p53, Bax, and Bcl-XL) suggested a possible apoptotic pathway of cell death. AKL-40 also inhibited the growth of human erythroleukemia cells, probably via activating the MAPK/ERK pathway, but did not affect human B-lymphoma cells (Raji) or rat basophilic leukemia cells (RBL-1). In vitro, lectin suppressed the growth of Ehrlich ascites carcinoma and U937 cells by 37.9% and 31.8%, respectively. Along with strong antifungal activity against Talaromyces verruculosus, AKL showed antibacterial activity against Staphylococcus aureus, Shigella sonnei, and Bacillus cereus whereas the growth of Escherichia coli was not affected by the lectin. This study explores the antiproliferative and antimicrobial potentials of AKL as well as its involvement in embryo defense of sea hare.     

Anti-Alzheimer’s Molecules Derived from Marine Life: Understanding Molecular Mechanisms and Therapeutic Potential

Alzheimer’s disease (AD) is a devastating neurodegenerative disease and the most common cause of dementia. It has been confirmed that the pathological processes that intervene in AD development are linked with oxidative damage to neurons, neuroinflammation, tau phosphorylation, amyloid beta (Aβ) aggregation, glutamate excitotoxicity, and cholinergic deficit. Still, there is no available therapy that can cure AD. Available therapies only manage some of the AD symptoms at the early stages of AD. Various studies have revealed that bioactive compounds derived from marine organisms and plants can exert neuroprotective activities with fewer adverse events, as compared with synthetic drugs. Furthermore, marine organisms have been identified as a source of novel compounds with therapeutic potential. Thus, there is a growing interest regarding bioactive compounds derived from marine sources that have anti-AD potentials. Various marine drugs including bryostatin-1, homotaurine, anabaseine and its derivative, rifampicins, anhydroexfoliamycin, undecylprodigioisin, gracilins, 13-desmethyl spirolide-C, and dictyostatin displayed excellent bioavailability and efficacy against AD. Most of these marine drugs were found to be well-tolerated in AD patients, along with no significant drug-associated adverse events. In this review, we focus on the drugs derived from marine life that can be useful in AD treatment and also summarize the therapeutic agents that are currently used to treat AD.     

Developing capacity of forest users through participatory forest management: Evidence from Madhupur Sal forest in Bangladesh

Participatory forest management is credited for supporting social learning processes and fostering capacity of forest users for collaboration and collective actions. Despite more than a decade of practice, the empirical evidence substantiating the contribution of participatory management for the capacity development of forest users is scarce. This study assesses a participatory forest management program in Madhupur Sal forest, Bangladesh, by comparing the capacity of de-facto groups of participants and nonparticipants and identifies factors that influence the capacity development. Data were collected using a mixed method approach which combines both qualitative and quantitative methods of data collection. Results indicate that participants differed from nonparticipants significantly in terms of various capacity dimensions related to collective actions. Extension services, credit support, trust within society, information and communication influence the level of capacities in tribal population to adapt and respond to changes. The initiatives to manage natural resources are likely to be more successful if the forest management program initiators consider several factors that influence the capacity development of resource users.     

Effects of different salinity and temperatures on the growth,survival, haematocrit and blood biochemistry of Goldfish (Carassius auratus)

The aim of the present study was to investigate the effects of different salinities (0‰, 6‰ and 12‰) and temperatures (23, 27 and 31 °C) on the food consumption, growth, blood biochemistry and haematocrit of Goldfish. After 45 days of exposure to different salinities and temperatures, Goldfish showed a good adaptation to these salinities and temperatures in terms of blood biochemistry (glucose and triglyceride) and haematocrit. Salinities (0‰ and 6‰) and temperatures (23 and 27 °C) did not affect the weight gain, specific growth rate, final biomass and feed conversion rates, but these parameters were significant (P<0.05) at 12‰ salinity and 31 °C temperature. Plasma total protein levels decreased with the increase in salinity (P<0.05), while they were independent of temperature. In conclusion, Carassius auratus, a freshwater stenohaline fish, showed good growth in saline waters with maximum 12‰ salinity and 31 °C temperature.     

Household and homegarden characteristics in southwestern Bangladesh

Homegardens around the world often exhibit remarkable variation in composition and structure depending on the physiographic and climatic conditions of the area and a wide variety of household characteristics. This research investigated whether households’ contextual attributes have a quantitative and predictable relationship with homegarden vegetation structure from a total of 402 randomly selected households in southwestern Bangladesh. The central analytical tool to test the relationship between household characteristics and the homegarden vegetation structure was multiple regression. The moderate to low regression R ² values revealed that most household characteristics were not strong predictors of homegarden vegetation structure. Despite the weak explanatory power of the majority household characteristics, time spent and homestead size had the strongest relationship with species richness and income in a homegarden. Households being the main source of labor for a majority of households suggest that outside labor shortage would not influence homegarden vegetation structure. We suggest that women’s active participation in homegardening activities to reduce gender inequality in the family which will perhaps result in more diverse and economically viable homegarden. However, increasing population density and the concomitant fragmentation of landholdings to homesteads may create opportunity for homegarden promotion in Bangladesh. Our results of decreased species richness in the homegarden with improved roads and proximity to market support the general hypothesis of subsistence homegardens and did not reinforce the general fears of gradual decline in species richness due to a market economy. Household characteristics had no influence on the presence of IUCN Red Listed species in the homegarden, except for gender and education of the household head. However, most homegardeners were unaware about the status of red listed species, suggesting that occurrence of red listed species in homegardens was by chance. Thus, efforts to improve awareness and to save and conserve rare species from extirpation are needed.     

RELEVANCE OF A RAPID APPRAISAL APPROACH TO IDENTIFY LOCALLY AVAILABLE FEED INGREDIENTS TO SMALL-SCALE NILE TILAPIA (Oreochromis niloticus L.) AQUACULTURE

Applications of a rapid appraisal approach to identify locally available feed ingredients in feed formulation, production, and socio-economics of Nile tilapia aquaculture in Bangladesh are discussed. Three diets of 35%, 30%, and 25% crude protein were formulated using locally available ingredients, and their essential amino acid profiles were assessed for Nile tilapia. Six production scenarios were constructed using these diets and two culture periods of 100 and 150 days were considered. The production scenarios with 35% protein yielded the highest productivity and profitability over the 150-day culture period followed by the 30% protein scenario. Identification of locally available ingredients and their application in small-scale Nile tilapia aquaculture may lead to: (1) increased availability of inexpensive sources of fish production for poor people; (2) increased fish consumption; (3) increased self employment and involvement of women in productive activities; and (4) increased household income to reduce poverty.