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Shewanella putrefaciens: an emerging pathogen for farmed yellow catfish Pelteobagrus fulvidraco
Get PDFBacteriosis has caused significant economic losses in farmed yellow catfish Pelteobagrus fulvidraco. Information is limited on Shewanella putrefaciens as a pathogen for yellow catfish. In this study, a virulent strain, temporarily named Y2, was isolated from diseased yellow catfish, identified phenotypically and molecularly as S. putrefaciens. A phylogenetic tree was constructed to examine isolate Y2 and compare it to other known isolates. In addition, isolate Y2 is apparently susceptible to aminoglycosides and tetracycline drugs for veterinary use in aquaculture as revealed when screened against a range of common antibiotics. To the best of our knowledge, this is the first report of S. putrefaciens as an emerging pathogen for cultured yellow catfish
Intestinal fatty acid binding protein gene (I-FABP) in golden pompano Trachinotus ovatus (Linnaeus 1758) larvae: ontogenetic expression and response to water temperature and nutrition manipulation
Get PDFThe gene for fatty acid binding proteins (I-FABP) in golden pompano Trachinotus ovatus larvae was cloned and analyzed from hatch to 18 days-post hatch (DPH). The I-FABP gene (GenBank accession: MF034871) of golden pompano is composed of 815 bp with an open reading frame of 399 bp, encoded in one amino acid with a molecular weight of 15.24 kDa. The predicted amino acid sequence of I-FABP genes from golden pompano showed high similarity and identity with Japanese sea bass Lateolabrax japonicus (97% and 87.9%, AOW69620.1). The highest tissue expression of I-FABP genes was found in the intestine, followed by the eye on 18 DPH. During the ontogenetic development, the expression of I-FABP genes remained at a low level during the first five days, and reached the highest level on 12 and 18 DPH. The expression of I-FABP genes was not significantly affected by environmental temperature on 12 DPH, but was significantly affected by the temperature on 18 DPH. Nutrition enhancement with algae containing high fatty acids significantly affected the expression of I-FABP genes. The highest expression was observed in the non-enriched treatment, but the lowest expression was in the Nannochloropsis feeding treatment. Results of the present study indicate that the expression of the I-FABP gene varies with environmental temperature and nutritional conditions during the ontogenetic development of golden pompano larvae. The expression of I-FABP genes may be potentially used as an indicator for assessing nutrient supply and functional development of the digestive system in fish larvae
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Get PDFNewsletter Vol. 42 no. 6Monthly newsletter of the Institute for Research, Extension and Training in Agriculture and School of Agriculture, located in Apia, Samoa
Multiplex Taqman Real-Time Pcr For Detecting Aeromonas Hydrophila, A. Veronii and A. Schubertii
Get PDFIn this study, pathogenic Aeromonas hydrophila, A. veronii, and A. schubertii from fish were detected by multiplex TaqMan real-time PCR assay. The assay utilized three pairs of specific primers and three corresponding TaqMan probes designed to detect the aerolysin gene in A. hydrophila, the aerolysin gene in A. veronii, and the gyrB gene in A. schubertii. The specificity of the probe and primers was evaluated. The detectable concentration for the multiplex real-time PCR was 3.33×10^1 copies/μL per reaction, respectively. In addition, the coefficient of variation was less than 1.5% for both intra-and inter-assay. The assay, when screened for 120 cultured fish samples, showed 76.7% positive for Aeromonas spp. and could accurately identify these bacterial strains. These results indicated that this assay could be used as an effective tool for rapid detection and epidemiology investigation of A. hydrophila, A. veronii, and A. schubertii