Grouper Epinephelus Malabaricus Research Articles

Biodegradation of the pyrethroid pesticide cyfluthrin by the halophilic bacterium Photobacterium ganghwense isolated from coral reef ecosystem

A halophilic bacterial strain T14 isolated from the mucus of coral Acropora sp. was found to be highly effective in degrading the pyrethroid pesticide, cyfluthrin. T14 was identified as Photobacterium ganghwense (GenBank Accession No. MT360254) based on phenotypic and biochemical characteristics as well as by 16S rRNA gene sequence analysis. The pyrethroid degrading efficiency of P. ganghwense T14 strain was examined under different culture conditions. It was observed that P. ganghwense T14 was able to utilise cyfluthrin as a sole carbon source and was found to grow on mineral medium with pesticide concentrations ranging from 10 to 100 mg l-1. Optimal temperature and pH conditions for efficient cyfluthrin degradation by P. ganghwense T14 were determined as 30° C and 8 respectively. Degradation of cyfluthrin by P. ganghwense T14 was quantitated by gas chromatography-tandem mass spectrometry (GC-MS/MS). Mineral medium supplemented with 100 mg l-1 cyfluthrin and inoculated with P. ganghwense T14 (106 cells ml-1) recorded 92.13% pesticide decomposition within 120 h. Cytotoxicity assay on a fish cell line EM4SpEx derived from the grouper Epinephelus malabaricus, revealed a drastic reduction in cyfluthrin toxicity as evidenced by reduction in the intensity of cell destruction as well as morphological changes when exposed to P. ganghwense T14 treated filtrate, in comparison with that of parent cyfluthrin filtrate. Results of the study clearly indicated potential bioremediative use of P. ganghwense T14 in cyfluthrin contaminated sites.

TỔNG QUAN VỀ VIỆC SỬ DỤNG SELEN (Se) TRONG NUÔI TRỒNG THỦY SẢN

Effects of antibiotics usage in aquaculture on environment and human health has prompted the search for alternative products. Recently, the microelements in organic form have been used as alternative to antibiotics in aquaculture. Se is one of the microelements that have received heightened attention. This report reviews the role of Se in the culture of fishes (cobia Rachycentron canadum L., red sea bream Pagrus major, fingerling channel catfish Ictalurus punctatus, seabass Lates calcarifer, snubnose dart Trachinotus blochii, rainbow trout Oncorhynchus mykiss, common carp Cyprinus carpio L., Atlantic salmon parr Salmo salar, nile tilapia Oreochromis niloticus, african catfish Clarias gariepinus, Senegalese sole Solea senegalensis, grouper Epinephelus malabaricus, gilthead seabream Sparus aurata, Chinook salmon Oncorhynchus tshawytscha, fathead minnow Pimephales promelas, striped bass Morone saxatilis, bluegill Lepomis macrochirus, crucian carp Carassius auratus gibelio) and crustacean (giant freshwater prawn Macrobrachium rosenbergii, white shrimp Penaeus vannamei, marron Cherax cainii, crayfish Procambarus clarkii). Suggestion for further research on the application of Se in aquaculture is also included.

The effects of a sudden salinity change on cortisol, glucose, lactate, and osmolality levels in grouper Epinephelus malabaricus

Grouper Epinephelus malabaricus (weighing 46.37±5.10g) previously maintained in 24‰ seawater were transferred to 14, 19, 24 (control), 29, and 34‰ seawater. Serum cortisol, glucose, lactate, and osmolality levels were measured at 7 time points during 240min. Serum cortisol and glucose levels of fish transferred to 29 and 34‰ seawater significantly increased to the highest after 10 and 20min, respectively. No significant differences in serum cortisol and glucose levels were observed for the fish after 30min among all treatments. Serum lactate level of fish transferred to 14, 19, 29, and 34‰ seawater was significantly lower than that of the control fish after 10-30min. However, no significant differences in serum lactate were observed 60min among five treatments. The serum osmolality of the fish following 240-min transfer increased directly with salinity, whereas the osmoregulatory capacity value (medium osmolality-plasma osmolality) of the fish following 240-min transfer was inversely related to salinity. It is concluded that grouper showed strong osmoregulation in 14-34‰ seawater. Serum cortisol and glucose levels of fish transferred to 29 and 34‰ seawater increased rapidly in 10-30min, indicating an early stress response.

Virus-like particles of a fish nodavirus display a capsid subunit domain organization different from that of insect nodaviruses.

The structure of recombinant virus-like particles of malabaricus grouper nervous necrosis virus (MGNNV), a fish nodavirus isolated from the grouper Epinephelus malabaricus, was determined by electron cryomicroscopy (cryoEM) and three-dimensional reconstruction at 23-A resolution. The cryoEM structure, sequence comparison, and protein fold recognition analysis indicate that the coat protein of MGNNV has two domains resembling those of tomato bushy stunt virus and Norwalk virus, rather than the expected single-domain coat protein of insect nodaviruses. The analysis implies that residues 83 to 216 fold as a beta-sandwich which forms the inner shell of the T=3 capsid and residues 217 to 308 form the trimeric surface protrusions observed in the cryoEM map. The structural similarities between fish nodaviruses and members of the tombusvirus and calicivirus groups provide significant new data for understanding the evolution of the nodavirus family.