Browsing by Author "Seraspe, Ebonia B."
ArticleEB Seraspe, BF Ticar, MJ Formacion, IG Pahila, MR de la Peña & EC Amar -
Asian Fisheries Science, 2012 - Asian Fisheries SocietyThe antibacterial properties of the microalgae Chaetoceros calcitrans were assessed. Samples of C. calcitrans were first extracted in methanol, and then in different organic solvents of increasing polarity, n-hexane (n-Hex), dichloromethane (DCM) and ethyl acetate (EA) by liquid-liquid extraction. Solvent extracts were screened for antibacterial activity against four species of bacteria: Gram positive, Staphylococcus aureus and Bacillus subtilis; and Gram negative, Escherichia coli and Vibrio harveyi, with Amoxicillin as positive control, N-Hex extract, with significantly lower antibacterial activity than Amoxicillin, showed significantly higher activity than DCM and EA extracts, and least in methanolic extract. High antibacterial activity of n-Hex extract against all the microorganisms indicates that the bioactive components could be non-polar since the activity decreased as the solvent became more polar like methanol, and finally lost in aqueous extract. Results also showed that the extracts have a broad spectrum activity. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of all solvent extracts on all microorganisms tested ranged from 125 to 500 μg.mL-1. Partial purification and characterisation of the extracts confirmed the antibacterial activity in the non-polar fraction, which could be terpenes. The results suggest a good prospect in using C. calcitrans against Vibrio and other bacterial species.
Evaluation of dietary freeze-dried Chaetoceros calcitrans supplementation to control Vibrio harveyi infection on Penaeus monodon juvenile Effects of supplementation of diets with freeze-dried Chaetoceros calcitrans to control Vibrio harveyi infection are evaluated through immune responses, and disease resistance of juvenile Penaeus monodon. Total lipid and fatty acid profile of Chaetoceros calcitrans is also analyzed. A challenge infection with 107 cfu/mL concentration of Vibrio harveyi is intramuscularly injected to juvenile Penaeus monodon after 45 days of feeding of diets supplemented with 15 g/kg and 30 g/kg dried Chaetoceros calcitrans. The use of dried Chaetoceros calcitrans is compared with that of ß-1,3 glucan Curdlan, a commercial immune enhancer. Incorporation of 30 g/kg Chaetoceros calcitrans in the diet enhances the immune system of shrimp as effected by high prophenoloxidase activity and plasma protein concentration and is better compared to the commercially available Curdlan. Chaetoceros calcitrans also contains polyunsaturated fatty acids (PUFAs) such as linolenic acid and eicosapentanoic acid (EPA) which are responsible for its antibacterial action against Vibrio harveyi. All these biological activities of Chaetoceros calcitrans add up to increase resistance of the juvenile Penaeus monodon to vibriosis as shown by its high survival rate from the challenge infection with Vibrio harveyi. Therefore, it is worthwhile to use Chaetoceros calcitrans as supplementary feed. Its effect in increasing the immune competence coupled with its antibacterial action, make the shrimp resistant to luminous vibriosis that continues to affect the industry, thereby augmenting aquaculture production.
Conference paperEB Seraspe, CH Tan & TJ Lam - In CL Marte, GF Quinitio & AC Emata (Eds.), Proceedings of the Seminar-Workshop on Breeding and Seed Production of Cultured Finfishes in the Philippines, Tigbauan, Iloilo, Philippines, 4-5 May 1993, 1996 - Aquaculture Department, Southeast Asian Fisheries Development CenterThe role of cyclic AMP in oocyte maturation was investigated using denuded goldfish oocytes cultured in vitro. The oocytes were stimulated with a maturation-inducing steroid (MIS), 17α, 20ß dihydroxy-4-pregnen-3-one (17, 20 P) with or without forskolin or forskolin only. Changes in cAMP concentrations and percent maturation of the oocytes were determined. Results showed that elevated levels of cAMP maintain the oocytes in meiotic arrest while a decrease would trigger the resumption of meiotic maturation.