Browsing by Author "de la Peña, Milagros R."
Antimicrobial activity screening of Lyngbya majuscula crude methanolic extract against selected aquaculture pathogens LG Ayukil III, EB Seraspe, DEG Corda, IG Pahila & MR de la Peña -
Philippine Journal of Natural Sciences, 2010 - University of the Philippines VisayasLyngbya majuscula crude methanolic extract (LMCME) was screened for antimicrobial properties in vitro. The Gram-negative Vibrio harveyi and Aeromonas hydrophila and the Gram-positive Staphylococcus aureus and Micrococcus luteus were used as reference test bacteria. The filamentous Lagenidium sp. was used as test fungus. LMCME showed a poor or weak antibacterial activity against the bacterial isolates. The activity against V. harveyi was observed at 1,000 mg/mL-1 while that against A. hydrophila was at 500 and 1,000 mg/mL-1 concentrations. These activities, however, were significantly lower (p<0.05) than the positive control (chloramphenicol). The activity of LMCME against S. aureus and M. luteus was observed in all the test concentrations, but it was against the M. luteus that the extract had high antibacterial activity. This activity, however, was significantly lower (p<0.05) than chloramphenicol. The antifungal activity test exhibited 100% mycelial growth inhibition at 100 mg/mL-1 concentration and was comparable (p>0.05) with the positive control (malachite green). The minimum inhibitory concentration (MIC) of LMCME against Lagenidium sp. was at 50 mg/mL-1, and the minimum fungicidal (lethal) concentration (MFC) at 100 mg/mL-1. Phytochemical screening revealed the presence of alkaloids to which its antifungal activity may be attributed. Brine shrimp assay against the larvae of Artemia salina L each showed that the LMCME was not toxic even at the highest concentration (1,000 mg/mL-1). By and large, L. majuscula can be a potential source of secondary metabolites that can be used for the control and treatment of larval mycosis in the aquaculture industry.
ArticleK Adachi, K Arai, MR de la Peña, S Moriyama & SI Okumura -
Journal of Shellfish Research, 2018 - National Shellfisheries AssociationGenome size (C-value) and the percentage of adenine and thymine nucleotides in the genome (AT content) are fundamental characteristics of every species, and very important parameters in molecular cytogenetic and phylogenic studies, and for the progress of whole-genome sequencing. In this study, the C-value and AT content of nine abalone species inhabiting the Northwest Pacific (around Japan), Southeast Asia, South Africa, and Oceania were determined using flow cytometry. C-value ranged from 1.32 pg for Haliotis varia (Southeast Asia) to 2.01 pg for Haliotis laevigata (Oceania), and AT content ranged from 58.0% for Haliotis planata (Southeast Asia) to 66.3% for Haliotis diversicolor aquatilis (Southeast Asia). Reported chromosome numbers ranged from 2n = 32 to 36, and were higher in Oceanian, South African, and Northwest Pacific species (2n = 36) compared with the Southeast Asian group (2n = 32). This increase of chromosome number in the Oceanian species seems to be related to an increase in the DNA amount, unlike that of Haliotis midae (South African species). An increase of the C-value associated with an increase in DNA amount was also shown in the North Pacific group. These results suggest that increases in the DNA amount occurred independently in the ancestor of each of the different lineages.