Suvra Roy

Application of Probiotics in Shrimp Aquaculture: Importance, Mechanisms of Action, and Methods of Administration

ABSTRACT Shrimp aquaculture is the fastest growing animal food producing sectors in the world due to its high demand in developed countries; however, they are affected by diseases mainly caused by opportunistic pathogens results in huge economic losses. Today preventive and management measures are central concern to overcome such outbreak of diseases. The adverse effect of chemotherapeutics in shrimp farming has drawn attention for the development of non-antibiotic and environment friendly agents, which is one of the key factors for health management in shrimp aquaculture. In recent years, application of probiotics against virus and bacteria in shrimp farming had been a novel and safe approach since they promote the innate immune response. Probiotics for bacterial diseases like vibriosis is well reported, but for viral diseases, the authentic strains still need research. Apart from the discovery of new or better formulations, improvement in the probiotic benefits may be helpful. Thus, better and economic production methods, administration ways or combination with other preventive/therapeutic measures are welcomed. Further studies are still necessary to increase the knowledge about use of probiotics to control bacterial infections in shrimp but much more efforts are needed in the case of viral diseases. In this review, potential application of probiotics in shrimp aquaculture: importance, mechanisms of action and methods of administration are being focused. The article also explains the limitations and prospects of probiotics in sustainable and ecofriendly shrimp culture to augment the total shrimp aquaculture production.

Population structure and genetic diversity of Indian Major Carp, Labeo rohita (Hamilton, 1822) from three phylo-geographically isolated riverine ecosystems of India as revealed by mtDNA cytochrome b region sequences

Abstract The population structure and genetic diversity of Rohu (Labeo rohita Hamilton, 1822) was studied by analysis of the partial sequences of mitochondrial DNA cytochrome b region. We examined 133 samples collected from six locations in three geographically isolated rivers of India. Analysis of 11 haplotypes showed low haplotype diversity (0.00150), nucleotide diversity (π) (0.02884) and low heterogeneity value (0.00374). Analysis of molecular variance (AMOVA) revealed the genetic diversity of L. rohita within population is very high than between the populations. The Fst scores (−0.07479 to 0.07022) were the indication of low genetic structure of L. rohita populations of three rivers of India. Conspicuously, Farakka-Bharuch population pair Fst score of 0.0000, although the sampling sites are from different rivers. The phylogenetic reconstruction of unique haplotypes revealed sharing of a single central haplotype (Hap_1) by all the six populations with a point mutations ranging from 1–25 nucleotides.

In Silico Structural Studies and Molecular Docking Analysis of Delta6-desaturase in HUFA Biosynthetic Pathway

ABSTRACT Fish are an important source of highly unsaturated fatty acids (HUFA) such as eicosapentaenoic acid EPA (20:5 n-3) and docosahexaenoic acid DHA (22:6 n-3) and play a significant role in human nutrition. The fatty acyl delta6-desaturase (Δ6 desaturase) is a rate-limiting enzyme in the biosynthetic pathway of highly unsaturated fatty acids (HUFA) that converts polyunsaturated fatty acids (PUFA) such as linoleic (18:2n-6) and α-linolenic (18:3n-3) acids into HUFA. In this study, fatty acyl Δ6 desaturase was identified from pangasius (Pangasianodon hypophthalmus) and further analyzed for sequenced-based characterization and 3D structural conformation. Sequenced-based analysis revealed some important secondary information such as physicochemical property. e.g., isoelectric point, extinction coefficient, aliphatic index, and grand average hydropathy, among others, and also post-translational modification sites were identified. An evolutionary-conserved stretch of amino acid residue and a functionally significant conserved structural ancestor, N-terminal cytochrome b5 and membrane FADS-like superfamily, were identified. Protein association analysis showed a high confidence score with acyl-CoA synthetase, elovl5, elovl2, and phospholipase A2. Herein, we report, for the first time, a 3D native structure of Δ6 desaturase protein by homology modeling approach; molecular docking analysis was performed with linoleic (18:2n-6) and α-linolenic (18:3n-3) acids, which are the two key substrates in the HUFA biosynthetic pathway. This work provides insight into the structural and functional characterization of Δ6 desaturase, which is involved in HUFA biosynthesis as a rate-limiting enzyme.

Aquaculture Drugs: Sources, Active Ingredients, Pharmaceutic Preparations and Methods of Administration

Aquaculture remains a growing, vibrant and important food production sector. However, disease outbreaks have disrupted aquaculture production, often with severe socio-economic and ecological consequences. Anti-microbial chemotherapy has been used in aquaculture for over past 60 years and discovery of new and effective anti-microbial agents have changed the microbial virulence and severity of disease, leading to a dramatic reduction in morbidity and mortality, and contributing to significant advances in the health of the general population. Anti-microbials are used both as prophylactic, at times of heightened risk of disease and as therapeutic, when an outbreak of disease occurs in the system. There are several anti-microbials drugs used for fish health management however, information on anti-microbial used in aquaculture and pharmacokinetics and pharmacodynamics of administration is very limited. In recent years, the issues relating to antibacterial use in animal food is under severe scientific and public scrutiny due to human health concern. Besides providing protection against microbial infection, chemotherapy may complicate health management by triggering toxicity, resistance, residues and occasionally public health and environmental consequences. Therefore, highly efficient and relatively safer drug is required to develop with the emphasis on prevention, which is likely to be more cost-effective than cure, which will reduce the possible problems associated with excessive use anti-microbials.

Acute Phase Proteins and their Potential Role as an Indicator for Fish Health and in Diagnosis of Fish Diseases

The acute phase proteins are biochemically and functionally unrelated protein predominantly synthesized in the liver. The local inflammatory cells i.e. macrophages and neutrophils secretes various cytokines like IL-1, IL-6, IL-8 (interleukins) and TNF-α into bloodstream in response to injury and tissue damage, which stimulate hepatocytes to produce protein and release them into the circulation; these proteins are called as acute phase protein (e.g. C-reactive protein (CRP), serum amyloid A (SAA), metal binding protein, lysozyme, lectin, etc.). The acute phase proteins are involved in variety of defence related activities e.g., inactivation of proteolytic enzymes, preventing the distribution of infectious agents (i.e. either by destruction of microorganism or making microbial cell suitable for cell response by modifying surface targets) and restoration of damage tissue and healthy condition. A number of well-known acute phase proteins have disease prognosis importance and change in the APPs level reflects the presence and intensity of inflammation during infection or injury. Further studies are still necessary to develop our knowledge in diagnostic importance of different acute phase proteins in fish and more efforts are needed to differentiate the APPs levels in case of viral, bacterial and parasitic diseases.