Aeromonas hydrophila infection induces Toll-like receptor 2 (tlr2) and associated downstream signaling in Indian catfish, Clarias magur (Hamilton, 1822)

Motile Aeromonas septicaemia (MAS), caused by Aeromonas hydrophila, is one of the most significant bacterial disease responsible for mortality in Indian catfish, Clarias magur, a potential aquaculture species in the Indian subcontinent. In fish, innate immunity elicited by pathogen recognition receptors (PRRs) plays an important role in providing protection against bacterial infection. Information on PRRs including Toll-like receptors (tlrs) and their response to bacterial pathogens remains unexplored in magur. Toll-like receptor 2 (tlr2), a phylogenetically conserved germ-line encoded PRR recognizes specific microbial structure and trigger MyD88-dependent signaling pathway to induce release of various cytokines responsible for innate immune response. In the present study, tlr2 gene of magur was characterized and downstream signaling was studied following challenge with A. hydrophila. The full-length cDNA of magur tlr2 (mtlr2) comprised of 3,066 bp with a single open reading frame of 2,373 bp encoding 790 amino acids having a theoretical pI value of 6.11 and molecular weight of 90 kDa. Structurally, it comprised of signal peptide (1–42aa), one leucine-rich repeat region (LRR) at N-terminal (LRR1-NT: 50–73 aa) and C-terminal (LRR-CT: 588–608 aa), twenty LRRs in between, one trans-membrane (Tm) domain (609–631aa) followed by cytoplasmic TIR domain (670–783aa). Phylogenetically, mtlr2 is closely related to pangasius and channel catfish. Highest basal expression of mtlr2, myd88 and il-1β in spleen, nf-kb in anterior kidney was observed. Lowest basal expression of mtlr2 in skin and myd88, nf-kb and il-1β in muscle was detected. Significant up-regulation of mtlr2 and downstream expression occurred at 3, 8, 24 h post infection to A. hydrophila in important immune organs such as liver, spleen, intestine and kidney. These findings highlight the vital role of tlr2 in eliciting innate immune defence against A. hydrophila infection.

Changes in the level of oxidative stress markers in Indian catfish (Wallago attu) infected with Isoparorchis hypselobagri

Background Helminth infection and infestation in fishes are detrimental and have a major effect on fish health and fish production. Among various factors, parasitic infections are known to modulate antioxidant defences in fish. Similar to other aerobic animals, fish are also susceptible to the effect of reactive oxygen species and thus have well established intrinsic and efficient antioxidant defences. ‘Oxidative stress markers are an important indicator of the physiological state of the parasite and its host’. Indian catfish, Wallago attu is a freshwater fish that serves as the definitive host of the adult piscine trematode Isoparorchis hypselobagri. Our two years prevalence data signifies the intensity of the problem revealing a minimum of 5.5% and a maximum of 54% I. hypselobagri infection in Indian catfish W. attu (unpublished data). The present study aimed to achieve baseline data attributed to changes in some oxidative markers due to parasitic infection. Results During the present study, the level of enzyme activities of Catalase (CAT), Glutathione reductase (GR), Glutathione-S-transferase (GST), Glutathione peroxidase (GPx), Superoxide dismutase (SOD) and lipid peroxidation was investigated to explore the pathogenic impact on the fish host. The level of these oxidative stress markers was monitored in the swim bladder, liver, intestine and muscle of the host. We also recorded the enzyme activities in the parasite I. hypselobagri. Analysis of data revealed an elevation in GST, SOD, GR, GPx and CAT activity in the infected host tissue as compared to the non-infected fish. Further, we observed presence of GST, SOD, GR and GPx enzymes in the parasite I. hypselobagri while CAT did not show any enzyme activity. Conclusions Increased level of enzyme activity in liver, muscle and intestine of infected host has been recorded which indicates increased oxidative stress in the host due to parasitic invasion. The presence of antioxidant enzymes in the parasites suggests an active antioxidant defence system to avoid immune responses to long term survival and establishment in their host.

Pertumbuhan dan status eksploitasi ikan sembilang (Plotosus canius) di perairan Kota Tanjung Pinang, Kepulauan Riau, Indonesia

Research on the growth and exploitation status of indian catfish (Plotosus canius) is important in supporting the management of fish resources in the waters of Tanjungpinang City, Riau Islands. The study aims to determine the pattern of growth, growth parameters, and the status of indian catfish exploitation in the waters of Tanjungpinang City, Riau Islands Province. The study was conducted with a purposive sampling method of 3 stations with a total sample of 529 individual fish crosses. Analysis of growth and exploitation status data using FISAT II software and regression analysis using Excel 2017. This study resulted in a pattern of long relations and the weight of fish as a female and males both are negative allometric (faster increase in length than weight increase). The highest rate of exploitation of indian catfish is obtained from the data of 0.73 per year. This exploit value exceeds the optimum exploitation value of 0.5.

Pertumbuhan dan status eksploitasi ikan sembilang (Plotosus canius) di perairan Kota Tanjung Pinang, Kepulauan Riau, Indonesia

Research on the growth and exploitation status of indian catfish (Plotosus canius) is important in supporting the management of fish resources in the waters of Tanjungpinang City, Riau Islands. The study aims to determine the pattern of growth, growth parameters, and the status of indian catfish exploitation in the waters of Tanjungpinang City, Riau Islands Province. The study was conducted with a purposive sampling method of 3 stations with a total sample of 529 individual fish crosses. Analysis of growth and exploitation status data using FISAT II software and regression analysis using Excel 2017. This study resulted in a pattern of long relations and the weight of fish as a female and males both are negative allometric (faster increase in length than weight increase). The highest rate of exploitation of indian catfish is obtained from the data of 0.73 per year. This exploit value exceeds the optimum exploitation value of 0.5.

Fatty acid, amino acid and vitamin composition of indian catfish, magur (Clarias batrachus) and singhi (Heteropneustes fossilis)

The fatty acid, amino acid and fat soluble vitamin content of magur (Clarias batrachus) and singhi (Heteropneustes fossilis) were assayed from collected samples from different geographical locations. Length and weight of collected samples were (50-235g and 165-300 mm) for magur and (50-210g and 190-255mm) for singhi. The essential amino acid (EAA) and the non-essential amino acid (NEAA) content in magur and singhi did not differ significantly. The Vitamin A and D contents were significantly (P<0.05) higher in magur when compared to singhi. The Vitamin K content was significantly (P<0.05) higher in singhi compared to magur. Monounsaturated fatty acid (MUFA) content was 38.34±4.62 and 49.69±7.82 in magur and singhi respectively. Among the MUFA, oleic acid was significantly (P<0.05) higher in singhi. Palmitic acid was significantly (P<0.05) higher in magur than singhi. The PUFA content were 25.52±1.40 and 13.86±0.64 in magur and singhi respectively. The eicosapentanoic acid (EPA) and docosahexaenoic acid (DHA) content were 2.98±1.00 and 3.60±1.11; 2.25±0.86 and 1.60±1.09 respectively in magur and singhi. The ?3:?6 ratio in magur was 0.45:1 and in singhi 0.82:1. Both the catfishes were found to be nutrient rich with amino acid, fatty acid and vitamin.SAARC J. Agri., 14(2): 189-199 (2016)