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Flexibacter columnaris was isolated from 13 cultured Oreochromis niloticus showing respiratory disorders. The isolates developed typical swarming rhizoid colonies on Cytophaga agar medium. Antibiotic sensitivity test revealed the susceptibility of F. columnaris isolated to oxytetracycline, chloramphenicol and erythromycin. A marked difference in the pathogenicity of seven tested isolates was observed: two were highly virulent, one was moderately virulent and four were avirulent. No experimental infection could be induced with the highly virulent isolates except after injuring one of the natural barriers of the fish body. The severity of the disease and the increased median death time shortened by keeping infected fishes with injured gills in water containing ammonia. In naturally infected O. niloticus, the disease became chronic as indicated by the presence of excessive proliferative and necrotic changes. On the other hand, severe dilatation of branchial blood vessel, oedema and round cell infiltration proved that, the disease among experimentally infected tilapias was acute.

This study was conducted to evaluate the modulatory effect of aqueous extract of Curcuma longa (L.) against γ-irradiation (GR), which induces biochemical disorders in male rats. The sublethal dose of GR was determined in primary hepatocytes. Also, the effect of C. longa extract was examined for its activity against GR. In rats, C. longa extract was administered daily (200 mg/kg body mass) for 21 days before, and 7 days after GR exposure (6.5 Gy). The lipid profile and antioxidant status, as well as levels of transaminases, interleukin-6 (IL-6), and tumour necrosis factor α (TNFα) were assessed. The results showed that in hepatocytes, the aqueous extract exhibited radioprotective activity against exposure to GR. Exposure of untreated rats to GR resulted in transaminase disorders, lipid abnormalities, elevation of lipid peroxidation, trace element alterations, release of IL-6 and TNF, and decrease in glutathione and protein level of superoxide dismutase-1 (SOD-1) and peroxiredoxin-1 (PRDX-1). However, treatment of rats with this extract before and after GR exposure improved antioxidant status and minimized the radiation-induced increase in inflammatory cytokines. Changes occurred in the tissue levels of trace elements, and the protein levels of SOD-1 and PRDX-1 were also modulated by C. longa extract. Overall, C. longa exerted a beneficial radioprotective effect against radiation-induced oxidative stress in male rats by alleviating pathological disorders and modulating antioxidant enzymes.

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A total of 25 T. nilotica (S. niloticus) fish showing clinical altrations were subjected to clinical, P. M., complete parasitologic and bacteriologic examinations. Results of clinical and post-mortem exam inations revealed two forms of the disease: 1. The first was characterized by redness of the skin, presence of haemorrhagic patches of various size distributed all over the body and fins, exophthalmia and anal prolapse with abdominal distention, which was considered as the acute septicaemic form of the disease. 2. The second was characterized by roughness of the scales and their detachment from some parts of the body and formation of ulcers which were small at first, then became enlarged, have irregular shape, white centrally, surrounded by hyperemic zone and found on the lateral sides of the body. This was classified as chronic ulcerative form of the disease. Parasitologic examination of diseased fish revealed the presence of Ichthyophthirius multifilis protozoan which was considered as a stress factor. Bacteriologic examination of diseased fish revealed the presence of fourteen isolates of bacteria, morphologically and biochemically related to Aeromonas hydrophila. Biological experiments conducted on T. nilotica yearlings revealed that eight isolates of A. hydrophila were highly virulent, three isolates were moderately virulent and the other three isolates were avirulent to the tested fish. The infection with A. hydrophila to T. nilotica was transmitted experimentally by I/P and I/M routes and not transmitted by scarification of the epidermis. Crowdness was a major factor for increasing mortalities among inoculated tilapias. Besides, T. nilotica have been proved to be a good model for studying the biological properties of fish pathogenic bacteria.