Behavioural, chromosomal: aberrations and hematological changes associated with acute nitrite toxicity in African Catfish "clarias gariepinus"

This investigation presents the results of acute toxicity in Clarias gariepinus [C. gariepinus] exposed to median lethal dose of nitrite [58 mg/L] for 1, 2 and 4 days. The 96 hr LC[50] of nitirite for C. gariepinus was determined. Behavioural changes, as well as the developing lesions in nitrite-treated fish were recorded. Hematological changes and chromosomal aberrations induced were also observed. The results revealed that, the nitrite-treated fish developed a significant decrease in erythrocyte population, total leukocyte count, hematocrite vale and hemoglobin content. The percent of methemoglobin was highly significant increased in all nitrite-treated groups compared with controls. Serum cortisol was significantly higher in nitrite-treated fish for 4 days compared with control. Different types of chromosomal aberrations were observed as break, fragment, deletion, end to end, endomitosis and centromeric attenuation. The total aberrations were significantly increased in all nitrite-treated fish compared with controls. Addition of sodium chloride [25 mg sod. Chloride/1 mg nitrite] or transferring of fish to freshwater after 24 hr of exposure treat methemoglobinemia. Hemoglobin content and methemoglobin percent of recovered fish in both treatments returned nearly to the normal level within 24 hr post treatment

Vibriosis in some fishes: molecular characterization of fish pathogenic vibrios

Studies were undertaken to isolate and characterize vibrio species pathogenic to fish. Thirty six vibrio-like isolates were obtained from twenty one of 160 fish samples. Biochemically the collected isolates were identified as Listonella anguillarum biotype B and C, Vibrio alginolyticus and unidentified lactose-fermenting vibrio spp. Eight vibrio strains of different origins were selected and were grown onto tryptose soya agar with 5% sheep blood for preparation of outer membrane proteins [OMPs]. The OMP profiles of the tested strains were separated using sodium dodecyl- sulphate polyacrylamide gel electrophoresis [SDS- PAGE]. Dice index of similarity was determined with each strain. Analysis of OMPs showed that the local vibrio strains had 8-9 protein bands of molecular weight ranging from 19.7- 212.9 KDa and they contained three major protein bands of molecular weight 19.7, 36 and 80 KDa. Moreover, SDS - PAGE analysis of the local vibrio strains indicated OMP expression differences in protein between strains defined mutant and within the same species strains belonging to different biogroups possessed distinct electrophoretic banding proteins. In conclusion SDS-PAGE analysis of OMPs may be considered as sensitive, reliable and rapid diagnostic method to characterize vibrio isolates

Pathological and parasitological investigations of eels [anguilla anguilla] naturally infested with anguillicola crassus and pseudergasilus zacconi in Egypt

For the first time in Egypt Anguillicola crassus and Pseudergasilus zacconi were recognized and identified from Anguilla anguilla. The naturally diseased fish showed skin hemorrhages, low body gain and occasionally abdominal swelling. In anguillicolosis, the infected swim bladders showed great thickening of their wall and multiple areas of hemorrhages together with the presence of round worms floating in chocolate like material within their luminae. The prevalence of infection was 30% and the intensity of parasite ranged from 1- 15 worms per fish. Histopathologically, cross sections of adult worms and numerous ensheathed larvae were present inside the lumen of the examined swim bladders. Severe congestion, submucosal hemorrhages and mononuclear cellular infiltration were recorded. Epithelial hyperplasia and desquamation with fibrosis of the swim bladder wall were also detected. In pseudergasilosis, the gill lesions were represented by excess mucous secretion with presence of grayish white elongated nodules firmly attached to the gill filaments. Microscopical examination of the gills revealed presence of parasitic elements in-between destructed gill filaments with diffuse hemorrhages, mononuclear cellular infiltration and fusion of gill lamellae. The morphological description used in identification of recognized parasites is discussed in the text