University of the Philippines

About: University of the Philippines is a education organization based out in Quezon City, Philippines. It is known for research contribution in the topics: Population & Health care. The organization has 4589 authors who have published 4437 publications receiving 114846 citations. The organization is also known as: UP.

Divergence of the Venom Exogene Repertoire in Two Sister Species of Turriconus.

Abstract: The genus Conus comprises approximately 700 species of venomous marine cone snails that are highly efficient predators of worms, snails, and fish. In evolutionary terms, cone snails are relatively young with the earliest fossil records occurring in the Lower Eocene, 55 Ma. The rapid radiation of cone snail species has been accompanied by remarkably high rates of toxin diversification. To shed light on the molecular mechanisms that accompany speciation, we investigated the toxin repertoire of two sister species, Conus andremenezi and Conus praecellens, that were until recently considered a single variable species. A total of 196 and 250 toxin sequences were identified in the venom gland transcriptomes of C. andremenezi and C. praecellens belonging to 25 and 29 putative toxin gene superfamilies, respectively. Comparative analysis with closely (Conus tribblei and Conus lenavati) and more distantly related species (Conus geographus) suggests that speciation is associated with significant diversification of individual toxin genes (exogenes) whereas the expression pattern of toxin gene superfamilies within lineages remains largely conserved. Thus, changes within individual toxin sequences can serve as a sensitive indicator for recent speciation whereas changes in the expression pattern of gene superfamilies are likely to reflect more dramatic differences in a species' interaction with its prey, predators, and competitors.

Photosynthesis of Prochloron as affected by environmental factors.

Abstract: The effects of light intensity, pH, temperature, and UV irradiation on the photosynthetic rate of Prochloron isolated from the ascidian host Lissoclinum patella, collected from Palau, were examined. Photosynthesis increased with light intensity with saturation at 500 μmol/m2 per second. It was maximum at pH 8 to 9 but almost completely suppressed below pH 7. The optimum temperature was 35° to 40°C, but the photosynthesis was absent at ≤20°C and at 45°C. It was recovered when the symbiont was transferred from 1 hour of incubation at ≤20°C to 35°C but not when transferred from incubation at 45°C. Ultraviolet irradiation severely inhibited the photosynthesis of Prochloron in isolation but not in vivo. This protection was brought about by the tunic covering the ascidian colony, which contains UV-absorbing mycosporine-like amino acids. These results indicate that the characteristic condition of the tropical marine environment largely determines the ecological distribution of Prochloron, and the ascidian tunic protects the organism from UV radiation.

The terwilliger algebras of the group association schemes of s5 and a5

Abstract: Terwilliger proposed a method for studying commutative association schemes by introducing a non-commutative, semi-simple C-algebra, whose structure reflects the combinatorial nature of the corresponding scheme, and applied the method to the P and Q polynomial schemes. In this paper, we continue the initial investigation of Bannai and Munemasa of the Terwilliger algebras of group association schemes. In particular, we determine the structure of the Terwilliger algebras of the group schemes of S 5 and A 5.

Structural features of conopeptide genes inferred from partial sequences of the Conus tribblei genome.

Abstract: The evolvability of venom components (in particular, the gene-encoded peptide toxins) in venomous species serves as an adaptive strategy allowing them to target new prey types or respond to changes in the prey field. The structure, organization, and expression of the venom peptide genes may provide insights into the molecular mechanisms that drive the evolution of such genes. Conus is a particularly interesting group given the high chemical diversity of their venom peptides, and the rapid evolution of the conopeptide-encoding genes. Conus genomes, however, are large and characterized by a high proportion of repetitive sequences. As a result, the structure and organization of conopeptide genes have remained poorly known. In this study, a survey of the genome of Conus tribblei was undertaken to address this gap. A partial assembly of C. tribblei genome was generated; the assembly, though consisting of a large number of fragments, accounted for 2160.5 Mb of sequence. A large number of repetitive genomic elements consisting of 642.6 Mb of retrotransposable elements, simple repeats, and novel interspersed repeats were observed. We characterized the structural organization and distribution of conotoxin genes in the genome. A significant number of conopeptide genes (estimated to be between 148 and 193) belonging to different superfamilies with complete or nearly complete exon regions were observed, ~60 % of which were expressed. The unexpressed conopeptide genes represent hidden but significant conotoxin diversity. The conotoxin genes also differed in the frequency and length of the introns. The interruption of exons by long introns in the conopeptide genes and the presence of repeats in the introns may indicate the importance of introns in facilitating recombination, evolution and diversification of conotoxins. These findings advance our understanding of the structural framework that promotes the gene-level molecular evolution of venom peptides.

Genetic diversity and structure of the tropical seagrass Cymodocea serrulata spanning its central diversity hotspot and range edge

Abstract: Persistence of populations at their distributional ranges relies on local population dynamics and the fitness of species with low dispersal potential. We analyzed the population genetic diversity and structure of a tropical seagrass species, Cymodocea serrulata, at 34 sites spanning Philippine (diversity hotspot) and Ryukyu Islands (northern limit of distribution) populations using microsatellite (SSR) markers. Seagrass populations in the diversity hotspot are hypothesized to contain higher genetic diversity and clonal richness than those resulting from expansion or geographic range limits. We tested this hypothesis by comparing the genetic diversity, genetic structure and clonal richness of C. serrulata populations in the Philippines and Ryukyu Islands. C. serrulata populations showed decreased genetic diversity and clonal richness at their northern limit. Clonal reproduction predominated at the northern limit, while sexual reproduction prevailed in the diversity hotspot. Decreased genetic diversity and clonal richness at the northern limit may be the consequence of drift resulting from founder effect, reduced habitat, sea surface temperature and low gene flow and/or natural selection across life stages, wherein clonal reproduction confers greater environmental fitness. Analysis of molecular variance (AMOVA) and the fixation index, F ST, showed significant genetic differentiation within and among geographic populations. STRUCTURE analysis revealed that the Ryukyu Islands populations were mosaics of genets from the eastern Philippines, likely carried by the Kuroshio Current.