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    • Conference paper

      High throughput RNA sequencing reveals temperature tolerance mechanisms in Scylla serrata 

      MC Ablan-Lagman & E Meyer - In ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines, 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The effects of increasing temperature from global climate change threaten the sustainability and production of mud crabs from farms and wild populations in mangroves. Adaptation of mud crab populations to temperature stress is difficult to evaluate until now, with the emergence of RNA-Seq, a method which evaluates total mRNA expression under different conditions. In this study, 10 individuals each of S. serrata from Buguey, Cagayan were exposed to 26~’C and 32~’C for two weeks and the mRNA profiles were compared based on 186 million high quality pair-end reads which were aligned to a S. serrata reference transcriptome assembled de novo from 24,350 contigs with an average N50 of 1564 bp. Temperature related differences in gene expression were not significantly detected between the control and treatment groups and this was mostly due to the highly expressed genes such as the low and high molecular weight heat shock proteins. However, variations were greater among genes involved in the process of cell cycle regulation, the dissimilation processes such as oxidative phosphorylation, reproduction and transport across membranes. Greater differences were observed between immature or mature males and females.
    • Conference paper

      Population structure of Scylla serrata from microsatellite and mtDNA markers 

      CCE Vince Cruz & MC Ablan-Lagman - In ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines, 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Determination of the population structure and connectivity of natural populations of Scylla serrata are useful tools for decision making related to conservation and management efforts of this species. They provide important considerations as recovery and sustainability of the industry relies on the availability of hardy recruits that can replenish harvested resources from the system. In the case of marine domesticated species, admixture is expected due to commodity trade and exchanges.

      Current population structure of five wild populations of S. serrata from Pangasinan, Bataan, Cagayan, Quezon, and Panay was determined using five microsatellite markers, cross-amplified from Scylla paramamosain in a total of 259 samples. Mitochondrial 16S rDNA sequences of 25 representative individuals from the same locations were used to provide a comparison with original evolutionary patterns. Quality check of microsatellite data revealed no null alleles in the data set, with all loci and populations exhibiting Hardy-Weinberg Equilibrium. Pairwise FST analysis reveals FST values between 0.001-0.08432 with 9 out of the 16 possible comparisons considered significant. Phylogenetic analysis was performed on the 16S rDNA sequences, supported by bootstrap values. Both sets of data suggest 2 distinct groupings: the east coast populations of Cagayan and Quezon, the west coast populations of Pangasinan and Bataan, with admixture observed in the group from Panay. Additional data from 5 microsatellite markers specifically developed for S. serrata and the D-loop region will be added to the analysis.

      The results from both mitochondrial and microsatellite markers, revealing an East-West separation of S. serrata populations, suggest that current and evolutionary population patterns are matching. Aquaculture practices appear to have not yet significantly affected the population structure of this domesticated species, as initially speculated.