Isolation and Purification of an Anticoagulant from Schizymenia dubyi by Fermentation

Natural fermentation is a method of extracting anticoagulant compounds from red algae Schizymenia dubyi. Preliminary screening was carried out on the basis of the activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT) assays. The optimal fermentation time period for the highest APTT, PT, and TT values was found to be 8 weeks. Purification of the fermented sample by DEAE-anion exchange chromatography followed by Sepharose-4B chromatography resulted in a single polysaccharide, which was reconfirmed by a single spot on agarose gel electrophoresis. The purified sample had >1000s APTT activity at 130 μg/mL. The molecular weight estimated by polyaccrylamide gel electrophoresis was >500,000 Da. This is the first report indicating the presence of the anticoagulant compound in S. dubyi.

Effects of water temperature on mortality in Megalocytivirus-infected rock bream Oplegnathus fasciatus (Temminck et Schlegel) and development of protective immunity

Rock bream iridovirus (RBIV) causes huge losses, especially in rock bream Oplegnathus fasciatus. Rock bream injected with RBIV and held at 29, 26, 23 or 20 °C had 100% mortality. Conversely, all infected fish held at 17 °C survived even after the temperature was progressively increased to 26 °C at 100 dpi. Rock bream exposed to virus and held for 2, 4 and 7 days at 23/26 °C before the temperature was reduced to 17 °C had mortality rates of 26.6/73.2%, 66.6/100% and 93.4/100%, respectively, through 100 dpi. When surviving fish had the water temperature increased from 17 to 26 °C at 100 dpi, they did not exhibit signs of disease and had low virus copy numbers (below 10(3)). To investigate the development of a protective immune, rock bream were infected with RBIV and held at 23 °C before shifting the water temperature to 17 °C at 4 dpi. All injected fish survived until 120 dpi. While 100% of the previously unexposed fish died, 80.2% of the previously infected fish survived. When the survivors were rechallenged again at 160 dpi, no further mortality occurred. The high survival rate of fish following rechallenge with RBIV indicates that protective immunity was established in the surviving rock bream.