Browsing by Author "Palma, Peter A."
Gonadal response of juvenile protogynous grouper (Epinephelus fuscoguttatus) to long term recombinant follicle-stimulating hormone administration P Palma, J Nocillado, J Superio, EGdJ Ayson, F Ayson, I Bar & A Elizur -
Biology of Reproduction, 2018 - Oxford University PressThe role of follicle stimulating hormone (FSH) in the gonadal development of protogynous hermaphroditic grouper (E. fuscoguttatus) was investigated. Recombinant giant grouper (E. lanceolatus) FSH (rggFSH) was produced in yeast. Its receptor binding capacity and steroidogenic potency were confirmed in vitro. Weekly injections of rggFSH to juvenile tiger grouper for 8 weeks (100 μg/kg body weight, BW) resulted in significantly larger and more advanced oocytes (cortical alveolar stage vs. primary growth stage in control). Sustained treatment with rggFSH (20 to 38 weeks at 200 μg/kg BW) resulted in significant reduction in gonad size, degeneration of oocytes and proliferation of spermatogonial cells, indicative of female to male sex change. Gene expression analysis showed that, while initiating female to male sex change, the rggFSH significantly suppressed the steroidogenic genes cyp11b, cyp19a1a and foxl2 which restrained the endogenous production of sex steroid hormones thus prevented the differentiation of spermatogonial cells. Expression profile of sex markers dmrt1, amh, figla and bmp15 suggests that the observed sex change was restricted at the initiation stage. Based on these results, we propose that the process of female to male sex change in the protogynous grouper is initiated by FSH, rather than sex steroids and likely involves steroid-independent pathway. The cortical alveolar stage in oocyte development is the critical point after which FSH-induced sex change is possible in grouper.
Quantitative and qualitative analyses of the bacterial microbiota of tilapia (Oreochromis niloticus) cultured in earthen ponds in the Philippines R Pakingking Jr., P Palma & R Usero -
World Journal of Microbiology and Biotechnology, 2015 - Springer VerlagThe quantity and composition of the bacterial microbiota in the rearing water, sediment, gills and intestines of tilapia Oreochromis niloticus collected every 2 weeks from Day 30 to Day 120 after stocking for grow-out culture in 6 earthen brackish water ponds in the Philippines were examined. The total heterotrophic aerobic bacterial counts obtained in the water, sediment, gills and intestines of tilapia ranged from 103 to 104 c.f.u. ml−1, 103–105, 105–107 and 104–107 c.f.u. g−1, respectively. In terms of composition, a total of 20 bacterial genera and 31 species were identified with the preponderance of gram-negative bacteria constituting 84% of all bacterial isolates examined. Aeromonas hydrophila, Bacillus spp., Plesiomonas shigelloides, Shewanella putrefaciens, Pseudomonas fluorescens, Staphylococcus spp. and Vibrio cholerae were the dominant bacteria identified in the gills and intestine of tilapia. These bacteria also dominated in the pond sediment and rearing water, except for the nil isolation of S. putrefaciens and V. cholerae in the water samples examined, indicating that resident bacteria in the pond water and sediment congruently typify the composition of bacterial microbiota in the gills and intestine of tilapia which under stressful conditions may propel the ascendance of disease epizootics.
ArticlePA Palma, ER Cruz-Lacierda & VL Corre Jr. -
Bulletin of the European Association of Fish Pathologists, 2015 - European Association of Fish PathologistsTrichodiniasis was noted in an intensive milkfish (Chanos chanos) nursery pond in Dumangas, Iloilo, Philippines. It was predominantly caused by a small trichodinid species (body diameter=23-29 µm) with well-developed denticles, identified as Paratrichodina sp. The trichodinid infection resulted in proliferative changes, including clubbing and epithelial hyperplasis of the gill lamellae sufficient to disrupt respiratory function. Tolerance tests of milkfish fingerlings in an earthen pond-simulated environment resulted in a 24 h TL90 value of 1.98 ± 0.25 ppm KMnO4. A treatment of 1.0 ppm KMnO4 was highly efficacious (96%) in eliminating trichodinids on gills with minimal mortality of treated milkfish observed 24 hours post-treatment.