Determination of Saxitoxin by Receptor Binding Assay: A New Radiolabeled Kit in Thailand

Objective: A receptor binding assay for detection of saxitoxin, a paralytic shellfish poisoning toxin, was formatted for use in a high throughputdetection system using microplate scintillation counting. The RBA technology was transferred from the NOAA National Ocean Service, SC USA, tothe Thailand Institute of Nuclear Technology, which uses a Perkin Elmer Microbeta TriLux 1450 microplate scintillation counter. Methods: Validationof method was performed by participating in the regional inter-laboratory program. The result yielded all parameters within the critical control point(i.e. RSD less than 30%). Results: The slope of the calibration graph = 1.2 + 0.26 (RSD = 21.7%) (criteria = 0.8 - 1.2), half maximal inhibition (IC50)= 3.1 + 0.47 nM (RSD = 15.2%) (criteria = 3.0 nM), dynamic range = 1.2 - 10 nM and the limit of detection (IC80) from graph = 1.2 nM, equivalentto the limit of quantification of 2.57 mg/100 g shellfish. The result of analysis of unknown samples yielded the RSD between assays ranging from 6 -23% and the recovery compared to the expected value ranging from 79 -133%. The application of RBA for determination of PSP in shellfish samplesyielded RSD in assays less than 30% and between assays ranging from 1.4-15.2%. Conclusion: RBA for STX has showed a valuable for rapid,reliable, cost-effective alternative to live animal testing and high throughput screen prior to testing by the conventional mouse bioassay (MBA) and itssuitability for providing an early warning of increasing PSP toxicity when toxin levels are below the MBA limit of detection.Keywords: saxitoxin, receptor binding assay, paralytic shellfish poisoning, tritiumThai Pharm Health Sci J 2010;5(4):287-295

Urban coral reefs: Degradation and resilience of hard coral assemblages in coastal cities of East and Southeast Asia

© 2018 The Author(s) Given predicted increases in urbanization in tropical and subtropical regions, understanding the processes shaping urban coral reefs may be essential for anticipating future conservation challenges. We used a case study approach to identify unifying patterns of urban coral reefs and clarify the effects of urbanization on hard coral assemblages. Data were compiled from 11 cities throughout East and Southeast Asia, with particular focus on Singapore, Jakarta, Hong Kong, and Naha (Okinawa). Our review highlights several key characteristics of urban coral reefs, including “reef compression” (a decline in bathymetric range with increasing turbidity and decreasing water clarity over time and relative to shore), dominance by domed coral growth forms and low reef complexity, variable city-specific inshore-offshore gradients, early declines in coral cover with recent fluctuating periods of acute impacts and rapid recovery, and colonization of urban infrastructure by hard corals. We present hypotheses for urban reef community dynamics and discuss potential of ecological engineering for corals in urban areas