Estimation of Tissue Distribution of mRNA Transcripts for Desaturase and Elongase Enzymes in Channa striata (Bloch, 1793) Fingerlings using PCR Technique

Fish species are varied in their capacity to biosynthesize n-3 highlyunsaturated fatty acids (HUFA) such as eicosapentaenoic and docosahexaenoic acids (EPA & DHA) that are crucial to the health and well-being of all higher vertebrates. Experts report that HUFA metabolism involves enzyme-mediated fatty acyl desaturation (FAD) and elongation (FAE) processes. In previous studies, different workers cloned, characterized, identified and reported several genes for FAD and FAE enzymes in different fish species such as Atlantic salmon, gilthead seabream, rainbow trout and zebrafish, and also demonstrated the up- and down-regulation in the activity of these enzymes in response to fluctuations in dietary HUFA. In this paper, we report on the expression of genes (mRNA transcripts) for FAD and FAE enzymes in different tissues of Channa striata (Bloch, 1793) fingerling, to evaluate the tissues of the fish in which activity of both enzymes are high. To achieve this objective, we used conventional polymerase chain reaction (PCR) technique to isolate and quantify the absolute copy number for each gene transcripts from 8 different tissues of the fish (reared with a commercial feed). Our estimate show that the distribution of the 2 enzyme transcripts were significantly (P < 0.05) higher in the liver and brain of C. striata than detected in the 6 other tissues evaluated (muscle, ovary, testis, intestine, kidney and skin). Subsequently, we discuss here extensively, the implication of this observation with respect to the use of vegetable oils (VO) as substitute to fish oil (FO) in diets for freshwater fish species

Hemolymph coagulation and phenoloxidase activity in <i>Uca tangeri</i> induced by <i>Escherichia coli</i> endotoxin

<p><i>Uca tangeri</i> is a marine fiddler crab found commonly in the West African coast and is often exposed to Gram-negative pathogens upon injury. The aim of this study was to document the patterns of endotoxin-induced protein coagulation and phenoloxidase (PO) activity in hemolymph fractions of <i>Uca tangeri</i>. Hemolymph from live crabs was obtained by carapace puncture, pooled. and then separated into plasma, hemocyte Lysate (HL), hemocyte lysate supernatant (HLS) and hemocyte lysate debris (HLD). The effect of <i>Escherichia coli</i> (O1111:B4) endotoxin and calcium ion (Ca²⁺) on protein coagulation in the presence/absence of endotoxin and the endotoxin dose-dependence of coagulation and PO activity were each studied in the plasma, HL, HLS and HLD. The results showed Ca²⁺ was required to induce coagulation, and was endotoxin concentration-dependent in the plasma. PO activity was highest in the HLS but PO specific activity was highest in HLD. PO activity remained relatively constant with increased LPS concentration in the range studied 0–10 EU/ml. From the data we conclude that endotoxin-induced protein coagulation occurs in the plasma alone and might be mediated by trans-glutaminases, while PO activity is localized inside hemocytes and cell membranes in <i>Uca tangeri</i>.</p