The African sharptooth catfish (Clarias gariepinus) is indigenous to South Africa where it is commonly found in calm waters such as lakes, streams, rivers, swamps and floodplains. The males of this gonochoristic species can be readily distinguished from females via a distinct elongated urogenital papilla with a pointed tip, located just behind the anus. This structure is an androgen controlled ...

AIM To develop a method for conducting pulsed-field gel electrophoresis (PFGE) on Flavobacterium columnare, to use PFGE to characterize F. columnare channel catfish isolates, and to determine whether variation in pathogenic potential exists in F. columnare isolates from channel catfish. METHODS AND RESULTS On the basis of PFGE-derived profiles, similarity dendrograms constructed for more than...

The pathogenicity of a Streptococcus ictaluri isolate in channel catfish Ictalurus punctatus at the fry (0.5 g), fingerling (15 g), and juvenile (55 g) stages was determined by experimental bath immersion and injection experiments. Channel catfish were exposed in 1-L immersion baths containing 10(8), 10(9), 10(10), 10(11) or 10(12) colony-forming units (cfu) of S. ictaluri. Fish were also injec...

Oogenesis begins when the stem cell (oogonium) transforms into leptotene oocytes at the initiation of meiosis. The cell now called an oocyte produces the cellular material needed to complete the pre-vitellogenic phase of development. These may include gene amplification and organelle production. In addition, this leads to the accumulation of nutrients, messenger RNAs (mRNA), precursors of DNA a...

Oogenesis begins when the stem cell (oogonium) transforms into leptotene oocytes at the initiation of meiosis. The cell now called an oocyte produces the cellular material needed to complete the pre-vitellogenic phase of development. These may include gene amplification and organelle production. In addition, this leads to the accumulation of nutrients, messenger RNAs (mRNA), precursors of DNA a...

The fresh water catfish is the most predominant species of the teleost bred in captivity in Nigeria and has provided a model for the study of reproduction in aquatic vertebrates, but information on the number of mitotic divisions and spermatogonial generations remains inconclusive. This investigation aimed at assessing the number of generations of spermatogonia produced prior to meiotic divisio...

Fish oil was extracted from the viscera of African Catfish using supercritical carbon dioxide (SC-CO(2)). A Central Composite Design of Response Surface methodology (RSM) was employed to optimize the SC-CO(2) extraction parameters. The oil yield (Y) as response variable was executed against the four independent variables, namely pressure, temperature, flow rate and soaking time. The oil yield v...

To identify differentially expressed genes from channel catfish macrophages, a cDNA library from LPS-stimulated catfish macrophages was screened by subtractive hybridization. This screening yielded a 552-bp cDNA coding for catfish thioredoxin (CF-TRX). The deduced amino acid sequence revealed that CF-TRX contains 107 amino acids and is 59% homologous to human adult T cell leukemia-derived facto...

The present experiments were designed to determine the efficacy of metomidate hydrochloride as an alternative anesthetic with potential cortisol blocking properties for channel catfish Ictalurus punctatus. Channel catfish (75 g) were exposed to concentrations of metomidate ranging from 0.5 to 16 ppm for a period of 60 min. At 16-ppm metomidate, mortality occurred in 65% of the catfish. No morta...

Ferritins are the major iron storage protein in the cytoplasm of cells, responsible for regulating levels of intracellular iron. Ferritin genes are widely distributed in both prokaryotes and eukaryotes. In mammals, ferritin molecules are composed of heavy- (H) and light- (L) chain subunits; amphibian genomes contain three ferritin-type genes (H; middle, M; and L subunits); and teleost genomes t...