Researches:

Article title: Exploring the potential of clay in mitigating Pyrodinium bahamense var. compressum and other harmful algal species in the Philippines
Authors: Larry V. Padilla, Maria Lourdes San Diego-McGlone & Rhodora V. Azanza
Publication title: Journal of Applied Phycology 22(6):761-768, 2010

Abstract:
Harmful algal bloom occurrences worldwide have prompted the testing and use of methods to control and mitigate their detrimental effects. This study investigates the potential of Philippine clay minerals to physically remove phytoplankton cells under laboratory conditions. Ball clay had the highest removal efficiency (∼95%) for Pyrodinium bahamense (paralytic shellfish poisoning causative organism) cells. A slight decrease in the efficiency by 10–20% was seen when culture volume was increased from 50 mL to 1 L. Removal efficiency was reduced to ∼95% when water motion was introduced. Removal of other phytoplankton species (Gymnodinium sanguineum, Amphidinium carterae, Pyrophacus horologium, Chatonella marina, and Alexandrium sp.) using ball clay was less efficient (<70%). Cell removal efficiencies differed with phytoplankton species belonging to the same taxonomic group. Possible mechanisms for cell removal are described.
Full text available upon request to the author/s.

Article title: Immune response of tilapia (Oreochromis niloticus) after vaccination with autoclavekilled, heat-killed, and formalin-killed whole cell Aeromonas hydrophila vaccines as possible serotype-independent vaccines
Authors: Ivan Daryl C. Bactol, Larry V. Padilla and Allan L. Hilario
Publication title: International Journal of Agriculture and Biology 20(4):846-850, 2018

Abstract:
Nile tilapia, Oreochomis niloticus, is the most commonly produced and consumed fish in the Philippines. This fish is highly susceptible to Aeromonas hydrophila infection brought about by wastewater contamination. Since antibiotics are not routinely recommended in aqua farming, vaccination is the alternative way in preventing such bacterial infection. This study aimed to evaluate the immune response of Nile tilapia after vaccination with autoclave-killed, heat-killed and formalin-killed whole cells vaccine derived from Aeromonas hydrophila as possible serotype-independent vaccines. One hundred twenty Nile tilapia were randomly distributed into four tanks with corresponding treatments: normal saline solution (NSS), autoclave-killed vaccine (AKV), heat-killed vaccine (HKV), and formalin-killed vaccine (FKV) and were subjected to blood extraction 2 weeks after acclimatization and 2 weeks after vaccination. Immune response was evaluated using agglutination test. On post-vaccination, AKV had the highest mean antibody titer (p < 0.05). Pre-vaccination antibody level was significantly different to the post-vaccination antibody levels in AKV, HKV, and FKV (p < 0.05). This study showed that autoclave-killed, heat-killed, and formalin-killed whole cell Aeromonas hydrophila vaccines are possible serotype-independent whole cell vaccines that produced significant immune response in Nile tilapia.
Full text link https://tinyurl.com/2tmrkfzj

Article title: Preliminary Results On The Use Of Clay To Control Pyrodinium Bloom - A Mitigation Strategy
Authors: Larry V. Padilla, Maria Lourdes San Diego-McGlone, Rhodora V. Azanza
Publication title: Science Diliman 18(1):35-42, 2006

Abstract:
The frequent and expanded occurrence of Pyrodinium bahamense var compressum blooms in the Philippines since 1983 has prompted the need to find mechanisms to control the harmful effects of these toxic dinoflagellates. A promising method now being explored is the use of powdered clay minerals which when added to the growth media is capable of flocculating with the algal cells. In this study, the efficiency of ball clay, brown bentonite, and Malampaya Sound sediments to remove Pyrodinium cells in seawater was tested. The addition of 1 g/L of suspended ball clay to 50 mL of cultured Pyrodinium cells (~1.037 x106 cells/L) removed 99.56% of the algal cells after 2.5 hours. Prolonging the exposure time to 5 and 24 hours showed no significant increase in flocculation. Brown bentonite and Malampaya Sound sediments showed low to moderate removal efficiency not exceeding 70% and 50%, respectively. The effect of ball clay addition on seawater chemistry showed no change in ammonia concentration but nitrate decreased after 5 and 24 hours of clay addition. Results for nitrite and phosphate were however more variable.
Full text link https://tinyurl.com/yzt2rjmw

Article title: Effects Of Chronodisruption On The Locomotor Activity Of Zebrafish (Danio Rerio) Larvae
Authors: Larry V. Padilla, Divine Joy A. Mauhay, Fe Corazon A. Jacinto, Eileen Z. Vitug
Publication title: International Journal of Scientific & Technology Research 9(3):7255-7259, 2020

Abstract:
Zebrafish (Danio rerio) has been used as a vertebrate model organism for various biological assays and scientific studies. It has been reared and bred because of its importance to science and the aquarium industry. Rearing and breeding conditions varies depending on the operational procedures implemented by each rearing facility. Some of the disruptive factors affecting their growth, development, and behavior in these facilities are water quality, light, temperature and feeding cycles. There may be facilities that operate beyond the reported optimal light/dark cycle of 14L/10D for zebrafishes, hence affecting their physiology including their locomotor activity. In this study, the effects of disruption of light and dark cycles on the locomotor activity of zebrafish larvae were investigated. The zebrafish larvae were exposed after acclimation to optimal light cycle (from 1dpf to 5dpf) to different hemeral light and dark cycles (from 6 to 7 dpf): 1L/23D, 7L/17D, 14L/10D, 17L/7D, and 23L/1D. Results show that higher zebrafish larvae locomotor activity in terms of swimming bouts and swimming indices were obtained for those placed under shorter light cycles or longer dark periods. Zebrafish exposed to longer dark periods probably exhibited quiescent to low locomotor activity during dark phases, which enabled them to conserve energy for eventual use at the onset of light cycle. Higher swimming bouts were recorded for those exposed at 1L/23D and 7L/17D set ups than those placed under 17L/7D and 23L/1D set ups. No definitive trends were seen for swimming velocity and routine turns although variations in the activities were recorded among the different treatments. Statistical results showed that light disruption may affect locomotor activity in terms of routine turns and swimming velocity as early as 24 hours after changing the light and dark cycles. The disruptive effect was statistically significant for swimming bouts at 8 dpf. It is possible that prolonged exposure of these zebrafishes to disruption in light and dark cycles could aggravate the effects, not just to swimming bouts and index, but also for other physiological responses. The experiment only ran until 8 dpf, however, the influence of light as a zeitgeber had already been manifested.
Full text link https://tinyurl.com/5n92aecp

Article title: Critical evaluation of the hydrological, biological and sociological impacts of the implementation of flood control check dams in the Upper Marikina River Basin Protected Landscape, Philippines
Authors: Rej Winlove M. Bungabong, Wade L. Hadwen, Larry V. Padilla
Publication title: International Journal of River Basin Management 2021

Abstract:
Check dams, installed to control sediment and flood risk along streams, can significantly influence the hydrology and ecology of aquatic ecosystems. Few studies assessing its impacts have been done in some countries, however, such has not been the case in the Philippines. Implementation of check dam projects in the Philippines has not been paired with monitoring and evaluation strategies to determine their success or impacts in relation to their objective to manage sediment and flow. This study focused on assessing check dams impacts on hydrology, biology, and stakeholders reflection on check dam purpose and success in Upper Marikina River Basin Protected Landscape (UMRBPL), Philippines. To explore the balance in socioeconomic and ecological sustainability of check dam installation, interviews with stakeholders revealed a wide range of perceptions around the project’s success and potential impacts. The findings revealed a clear need for the enhancement of the enabling environment (i.e. data baselining and implementation of management strategies) and institutional arrangements (i.e. coordinated management action). There is also an urgent need for the development of management instruments (i.e. monitoring and evaluation programme and communication and awareness strategy) to improve stakeholders’ understanding of the project’s objectives and outcomes and to improve sustainable management throughout UMRBPL.
Full text available upon request to the author/s.

Article title: Endozoochory and Germination of Selected Ingested Seeds by Malayan Box Turtles (Cuoraamboinensis) from Laguna Province, Philippines
Authors: Kliff Eldry G. Ibañez and Larry V. Padilla
Publication title: Journal of Advances in Biology & Biotechnology 24(3):19-27, 2021

Abstract:
Aims: Malayan box turtles’ (Cuoraamboinensis) ecological niche are essential in an ecosystem but are often overlooked. This study investigated the germination of selected seeds that passed through the gut of Malayan box turtles to determine its role in promoting seed dispersal and aiding seed germination.

Study Design: Experimental approach. Place and Duration of Study:Pamantasan ng Lungsod ng Maynila (University of the City of Manila) and Dasmarinas, Cavite between June 2016 to March 2017.

Methodology: The seeds that passed through the turtle’s gut (Gut Passed Seeds) and seeds that did not pass through its gut (Mechanically Extracted Seeds) underwent comparative germination test. The Germination Rate (GR) and Percent Germination (%GR) of each group were determined in the study.Seed shadowing was also conducted to evaluate the turtle’s seed dispersal capacity (endozoochory).

Results: Results showed that after gut passage, seed GR and %GR were enhanced on Lycopersiconesculentum, Carica papaya, Psidiumguajava, and Muntingiacalabura. However, Germination Rate and Percent Germination of Passifloraquadrangularis decreased after gut passage. Statistical analyses revealed that there is a significant difference in the GR and %G of M. calabura and %G of L. esculentum, and P. quadrangularis. Thread trailing method showed that C. amboinensis can disperse seeds at a distance of 24.8 to 52.8 meters.

Conclusion: This study demonstrates the important role of C. amboinensis in the ecosystem through its contribution to plant seed germination and dispersal.It showed that Malayan box turtles are not only seed dispersal agents but are also important in the germination of seeds that they have ingested and defecated.
Full text link https://tinyurl.com/26a9psfr

Article title: Morphological Variation In Pollen Grains Of Philippine Hibiscus Rosa-Sinensis Hybrids
Authors: Divine Joy A. Mauhay, Larry V. Padilla, Fe Corazon A. Jacinto, Eileen Z. Vitug
Publication title: International Journal of Scientific & Technology Research 9(3):10-15, 2020

Abstract:
Hybridization of both plants and animals has innumerably benefitted man. An example of which is the numerous hybrids of Hibiscus rosa-sinensis which are primarily used for aesthetic purposes because of their colourful flowers. Phenotypic variations can already be observed in various parts of H.rosa-sinensis because of hybridization; hence, it is likely that modifications are occurring on microscopic structures such as the pollen. Through time, such variations could change the frequencies of alleles in the gene pool and could possibly lead to microevolution of the species. This study focused on the determination of variations in pollen grain morphology of ten (10) selected H. rosa-sinensis hybrids from the Institute of Plant Breeding of the University of the Philippines-Los Banos, specifically in terms of pollen aperture, size, shape, length of spine and sculpturing. The pollen shape, type of aperture and sculpturing were determined qualitatively. One-way ANOVA was employed if there is significant difference among the pollen of the hybrids in terms of the said quantitative characters. Pollen shape variation was determined through Elliptic Fourier Coefficient Analysis. Results showed that all hybrids have pantoporate type of aperture, echinate type of sculpturing, and spheroidal shape. Among the characters observed, variation was noted in their pollen size and spine length. Pollen size ranges from large to very large and long to very long spine length. Majority of the hybrids observed (7 out of 10) have very large pollen size and long pollen spines. One (1) hybrid has very large pollen size and short spines while two (2) have large pollen size and short pollen spines. There was also significant difference among the samples in terms of these characters based on statistical analysis. The hybrids with variations (Claire Baltazar x Cely Hermosa, Diamond Star and Vicky) cannot be considered outgroups on the basis of the said quantitative characters alone. Nevertheless, such variations observed should not be discounted as a possible modification in pollen morphology in progress as a result of hybridization.
Full text link https://tinyurl.com/mr2etez7

Article title: Anti-Quorum Sensing Activity of Tetracera scandens and Aleurites moluccana Leaf Extracts against Chromobacterium violaceum
Authors: John Paul Matthew D. Guzman and Larry V. Padilla
Publication title: Microbiology Research Journal International 22(1):1-10, January 2017

Abstract:
No abstract
Full text link https://tinyurl.com/2758hnaz