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This is the first report to describe the differential growth of cutaneous pigments and the molecular processes involved in two red discus (Symphysodon spp.), Red Melon and Red Cover, with different tones of red pigmentation develop from juveniles to adults. Microscopic observation detected xanthophores in all samples, erythrophores in both adult groups and Red Melon juveniles, while melanophores were only found in Red Cover. The skin transcriptome analysis revealed extracellular matrix (ECM) activities and collagen metabolic genes were elevated in both juveniles, as compared to the adults. The development of erythrophores and xanthophores in the Red Melon juveniles were regulated by genes involved in the pteridine synthesis, one-carbon metabolism, and lipid metabolism. Temporal inhibition of melanophore development in Red Melon juveniles might be attributed to the active expression of Wnt-signalling inhibitor genes, sost and notum2. Melanosome transport in Red Cover was likely relied on microtubules and the spectrin-associated cytoskeleton. Tyrosinase late N-glycan processing and its transport from Golgi apparatus into the melanosome were differentially expressed in RC adults and juveniles.

Seagrasses comprise the only submerged marine angiosperms, a feat of adaptation from three independent freshwater lineages within the Alismatales. These three parallel lineages offer the unique opportunity to study convergent versus lineage-specific adaptation to a fully marine lifestyle. Here, we present chromosome-level genome assemblies from a representative species of each of the seagrass lineages -Posidonia oceanica(Posidoniaceae),Cymodocea nodosa(Cymodoceaceae), andThalassia testudinum(Hydrocharitaceae)-along with an improved assembly forZostera marina(Zosteraceae). We also include a draft genome ofPotamogeton acutifolius, a representative of Potamogetonaceae, the freshwater sister lineage to the Zosteraceae. Genome analysis reveals that all seagrasses share an ancient whole genome triplication (WGT) event, dating to the early evolution of the Alismatales. An additional whole genome duplication (WGD) event was uncovered forC. nodosaandP. acutifolius. Dating of ancient WGDs and more recent bursts of transposable elements correlate well with major geological and recent climatic events, supporting their role as rapid generators of genetic variation. Comparative analysis of selected gene families suggests that the transition from the submerged-freshwater to submerged-marine environment did not require revolutionary changes. Major gene losses related to, e.g., stomata, volatiles, defense, and lignification, are likely a consequence of the submerged lifestyle rather than the cause (‘use it or lose it’). Likewise, genes, often retained from the WGD and WGT, were co-opted for functions requiring the alignment of many small adaptations (‘tweaking’), e.g., osmoregulation, salinity, light capture, carbon acquisition, and temperature. Our ability to manage and conserve seagrass ecosystems depends on our understanding of the fundamental processes underpinning their resilience. These new genomes will accelerate functional studies and are expected to contribute to transformative solutions — as continuing worldwide losses of the ‘savannas of the sea’ are of major concern in times of climate change and loss of biodiversity.

Benthic species, though ecologically important, are vulnerable to genetic loss and population size reduction due to impacts from fishing trawls. An assessment of genetic diversity and population structure is therefore needed to assist in a resource management program. To address this issue, the two-spined yellowtail stargazer (Uranoscopus cognatus) was collected within selected locations in the Indo-West Pacific (IWP). The partial mitochondrial DNA cytochrome c oxidase subunit 1 and the nuclear DNA recombination activating gene 1 were sequenced. Genetic diversity analyses revealed that the populations were moderately to highly diversified (haplotype diversity, H = 0.490–0.900, nucleotide diversity, π = 0.0010–0.0034) except sampling station (ST) 1 and 14. The low diversity level, however was apparent only in the matrilineal marker (H = 0.118–0.216; π = 0.0004–0.0008), possibly due to stochastic factors or anthropogenic stressors. Population structure analyses revealed a retention of ancestral polymorphism that was likely due to incomplete lineage sorting in U. cognatus, and prolonged vicariance by the Indo-Pacific Barrier has partitioned them into separate stock units. Population segregation was also shown by the phenotypic divergence in allopatric populations, regarding the premaxillary protrusion, which is possibly associated with the mechanism for upper jaw movement in biomechanical feeding approaches. The moderate genetic diversity estimated for each region, in addition to past population expansion events, indicated that U. cognatus within the IWP was still healthy and abundant (except in ST1 and 14), and two stock units were identified to be subjected to a specific resource management program.

Present study investigates the genetic diversity and genetic distribution of the longtail tuna Thunnus tonggol collected from east Malaysia (Borneo states of Sabah and Sarawak) based on mitochondrial DNA D-loop sequence analysis. 58 fish samples were obtained, specifically from Kota Kinabalu, KK (n = 22), Miri, MR (n=20) and Bintulu, BT (n = 17). DNA template was isolated using the salt extraction method. Final length of 404 base pair (bp) D-loop sequences revealed 52 haplotypes that comprise of 77 variable sites (38 of parsimony informative and 39 singleton). A total of 20 haplotypes were found in KK, 19 haplotypes in MR and 16 haplotypes in BT. Molecular diversity indices revealed high haplotype diversity and low nucleotide diversity in all populations; KK (h = 0.9913 ± 0.0165, π = 0.00239 ± 0.0127), MR (h = 0.9942 ± 0.0193, π = 0.0226 ± 0.0121) and BT (h = 0.9926 ± 0.0230, π = 0.0196 ± 0.0171). Population comparison pairwise FST show that KK and BT were significantly genetically differentiated. The result from this study will be beneficial for fisheries management and also to provide information on the population genetics of T. tonggol in East Malaysian waters.

Grouper aquaculture is rapidly expanding in both tropical and subtropical regions. The presence of marine leeches (

Present study provides a first characterization of the complete mitochondrial DNA (mtDNA) genome of the Pearse’s mudskipper Periophthalmus novemradiatus and describes its population genetics based on mtDNA cytochrome c oxidase subunit 1 (co1) gene. The whole mitogenome of P. novemradiatus is the fourth representative for its genus that consists of 23 formally described species to date. Eighty samples from six localities in Setiu Wetlands, Terengganu, Malaysia were sequenced at partial co1 gene region and analyzed, revealing an overall moderate haplotype diversity (h = 0.613) and low nucleotide diversity (π = 0.20%). Moreover, both the neutrality tests and mismatch distribution analyses of co1 suggest that the mudskipper populations might experience a genetic bottleneck or founder event followed by rapid expansion and accumulation of mutations dating approximately 46,251 years ago. Hap01 was the most dominant (61.13%) haplotype that present at all sampling locations, while five haplotypes were respectively observed in two to four locations, and nine haplotypes were singleton. This supports the close relationship of P. novemradiatus in Setiu Wetlands, as also corroborated in the population pairwise FST and genetic distance analyses. Interestingly, genetic propinquity with P. novemradiatus at Java and Bali, Indonesia (the only available sequences in GenBank) was also apparent, suggesting a common source of origin or long range dispersal ability of its planktonic larvae (> 1600 km). The lack of phylogeographic structure suggests there is no evidence of a barrier to gene flow between the South China Sea and Java/ Bali Sea and such pattern is most likely driven by ecological and environmental factor. Preservation of all the P. novemradiatus habitats in Setiu Wetlands is highly recommended because they each possess unique haplotypes present only at the respective location.

We sequenced and assembled three whole mitogenome sequences of the commercially important snakeskin gourami Trichopodus pectoralis isolated from Malaysia (introduced), Viet Nam (native) and Thailand (native). The mitogenome length range from 16,397 to 16,420 bp. The final partitioned nucleotide alignment consists of 14,002 bp and supports the monophyly of the genus Trichopodus (95% ultrafast bootstrap support) with T. trichopterus forming a sister group with the members of T. pectoralis.

Eighty-four specimens collected from 13 populations from Malaysia, Thailand, and Vietnam were analysed, revealing 21 putative haplotypes with overall estimated haplotype and nucleotide diversities of 0.79 and 0.0079, respectively. High levels of diversity and an absence of founder effects were observed among populations in peninsular Malaysia. In contrast, populations from Sarawak exhibited low genetic diversity, which is a typical sign of colonies introduced from a single source. Historical translocation of Trichopodus pectoralis from Thailand to Malaysia, as well as to the Philippines, Indonesia, and Myanmar was apparent. Historical introduction of T. pectoralis from Vietnam was also detected in peninsular Malaysia.

Plants and herbal extracts are indispensable for controlling the spread of disease-causing bacteria, including those that infect aquatic organisms used in aquaculture. The use of plant or herbal extract is expected to be safe for aquatic animals and less harmful to the environment, as opposed to conventional therapeutic alternatives such as antibiotics that promote the occurrence of potential antibiotic-resistant bacteria when used improperly. The efficacy of Pandanus tectorius fruit extract in the regulation of Hsp70 expression, pro-phenoloxidase (ProPO), peroxinectin, penaeidin, crustin and transglutaminase, all immune peptides essential for Vibrio tolerance in white leg shrimp, Penaeus vannamei, was investigated in this study, which included the determination of the safety levels of the extract. Tolerance of shrimp against Vibrio parahaemolyticus, a pathogenic bacteria that causes Acute Hepatopancreas Necrosis Disease (AHPND), was assessed on the basis of median lethal dose challenge survival (LD50 = 106 cells/ml). Mortality was not observed 24 h after exposure of 0.5–6 g/L of the fruit extract, indicating that P. tectorius was not toxic to shrimp at these concentrations. A 24-h incubation of 2–6 g/L of the fruit extract increased shrimp tolerance to V. parahaemolyticus, with survival doubled when the maximum dose tested in this study was used. Concomitant with a rise in survival was the increase in immune-related proteins, with Hsp70, ProPO, peroxinectin, penaeidin, crustin and transglutaminase increased 10, 11, 11, 0.4, 8 and 13-fold respectively. Histological examination of the hepatopancreas and muscle tissues of Vibrio-infected shrimp primed with P. tectorius extract revealed reduced signs of histopathological degeneration, possibly due to the accumulation of Hsp70, a molecular chaperone crucial to cellular protein folding, tissue repair and immune response of living organisms, including Penaeid shrimp.

The population genetic diversity and demographic history of the longtail tunaThunnus tonggolin Malaysian waters was investigated using mitochondrial DNA D-loop and NADH dehydrogenase subunit 5 (ND5). A total of 203 (D-loop) and 208 (ND5) individuals ofT. tonggolwere sampled from 11 localities around the Malaysian coastal waters. Low genetic differentiation between populations was found, possibly due to the past demographic history, dispersal potential during egg and larval stages, seasonal migration in adults, and lack of geographical barriers. The gene trees, constructed based on the maximum likelihood method, revealed a single panmictic population with unsupported internal clades, indicating an absence of structure among the populations studied. Analysis on population pairwise comparison ФSTsuggested the absence of limited gene flow among study sites. Taken all together, high haplotype diversity (D-loop = 0.989–1.000; ND5 = 0.848–0.965), coupled with a low level of nucleotide diversity (D-loop = 0.019–0.025; ND5 = 0.0017–0.003), “star-like” haplotype network, and unimodal mismatch distribution, suggests a recent population expansion for populations ofT. tonggolin Malaysia. Furthermore, neutrality and goodness of fit tests supported the signature of a relatively recent population expansion during the Pleistocene epoch. To provide additional insight into the phylogeographic pattern of the species within the Indo-Pacific Ocean, we included haplotypes from GenBank and a few samples from Taiwan. Preliminary analyses suggest a more complex genetic demarcation of the species than an explicit Indian Ocean versus Pacific Ocean delineation.

High-throughput sequencing technologies have expanded gene-based to genome-wide research in aquaculture species. Several techniques adopting the Second Generation Sequencing (SGS), Third Generation Sequencing (TGS) platforms and/or hybrid genome assemblies have been widely employed in various aquaculture research areas including general breeding program, disease and health management, sex determination and reproduction biology, environmental stress response, nutrigenomics, morphological appearance, and meat quality/texture. Notably, the application of these novel sequencing technologies has generated Quantitative Trait Loci (QTL) and novel genes associated with commercially important production traits, which are useful for essential processes in selective breeding programs such as population genomics evaluation, Marker-Assisted Selection (MAS) and Genomic Selection (GS). These genomic approaches are also used as genetic traceability tools for seafood fraud assessment and tracking of farm escapees for wild stock conservation. Genomic data generated by these platforms could aid in establishing proper breeding strategies for more profitable and sustainable aquaculture.

The population genetic diversity and demographic history of the longtail tuna Thunnus tonggol in Malaysian waters was investigated using mitochondrial DNA D-loop and NADH dehydrogenase subunit 5 (ND5). A total of 203 (D-loop) and 208 (ND5) individuals of T. tonggol were sampled from 11 localities around the Malaysian coastal waters. Low genetic differentiation between populations was found, possibly due to the past demographic history, dispersal potential during egg and larval stages, seasonal migration in adults, and lack of geographical barriers. The gene trees, constructed based on the maximum likelihood method, revealed a single panmictic population with unsupported internal clades, indicating an absence of structure among the populations studied. Analysis on population pairwise comparison ФST suggested the absence of limited gene flow among study sites. Taken all together, high haplotype diversity (D-loop = 0.989–1.000; ND5 = 0.848–0.965), coupled with a low level of nucleotide diversity (D-loop = 0.019–0.025; ND5 = 0.0017–0.003), “star-like” haplotype network, and unimodal mismatch distribution, suggests a recent population expansion for populations of T. tonggol in Malaysia. Furthermore, neutrality and goodness of fit tests supported the signature of a relatively recent population expansion during the Pleistocene epoch. To provide additional insight into the phylogeographic pattern of the species within the Indo-Pacific Ocean, we included haplotypes from GenBank and a few samples from Taiwan. Preliminary analyses suggest a more complex genetic demarcation of the species than an explicit Indian Ocean versus Pacific Ocean delineation.

Genetic variability and differences in wild striped snakehead Channa striata from Malaysia were analysed by genotyping nine novel nuclear microsatellite loci. Analysis revealed moderate-to-high genetic diversity in most of the populations, indicative of large effective population sizes. The highly diversified populations are admixed populations and, therefore, can be recommended as potential candidates for selective breeding and conservation since they each contain most of the alleles found in their particular region. Three homogenous groups of the wild populations were identified, apparently separated by effective barriers, in accordance with contemporary drainage patterns. The highest population pairwise FST found between members of the same group reflects the ancient population connectivity; yet prolonged geographical isolation resulted in adaptation of alleles to local contemporary environmental change. A significant relationship between genetic distance and geographical isolation was observed (r = 0·644, P < 0·01). Anthropogenic perturbations indicated apparent genetic proximity between distant populations.

Aquatic ecosystems that form major biodiversity hotspots are critically threatened due to environmental and anthropogenic stressors. We believe that, in this genomic era, computational methods can be applied to promote aquatic biodiversity conservation by addressing questions related to the evolutionary history of aquatic organisms at the molecular level. However, huge amounts of genomics data generated can only be discerned through the use of bioinformatics. Here, we examine the applications of next-generation sequencing technologies and bioinformatics tools to study the molecular evolution of aquatic animals and discuss the current challenges and future perspectives of using bioinformatics toward aquatic animal conservation efforts.

Brine shrimp Artemia franciscana release either encysted embryos via oviparous reproduction or motile nauplii via ovoviviparous reproduction. Artemia cysts contain an abundant amount of ArHsp21, ArHsp22, artemin, and p26, small heat shock proteins which regulate diapause and stress tolerance of this branchiopod crustacean. However, not much is known of the role of molecular chaperone, Hsp70 in this animal. In this study, the immunostimulatory role of Hsp70 in A. franciscana was investigated, work which included examining the function of this protein in embryo development, growth, survival and stress tolerance. Knockdown of Hsp70 was successfully performed by RNA interference (RNAi), with specific Hsp70 dsRNA construct delivered to female broods by microinjection to knockdown the protein in nauplii. The loss of Hsp70 neither affected the growth nor morphology as Artemia nauplii hatched normally and thereafter grew to adult within 28 days, observations similar to the control animals, the latter injected with GFP dsRNA. The survival of nauplii lacking Hsp70 appeared lower upon 28 days culture but the differences were insignificant when comparisons were made with the controls (P > .05). On other aspect, knockdown of Hsp70 reduced approximately 31% survival upon Vibrio campbellii challenge, indicating that Hsp70 assisted in the tolerance of Artemia nauplii during pathogen infection, perhaps through immune stimulation. Initial findings revealed that Hsp70 knockdown did not affect the expression of prophenoloxidase (proPO), a crucial immune protein of the shrimp innate immunity. By examining the morphology, growth, viability and molecular changes upon Hsp70 elimination, this study contributes to our understanding of the important roles of Hsp70 in A. franciscana, an important live food species used in aquaculture.

We explored the genetic diversity and structure of the striped snakehead (Channa striata) across Malaysia and Sumatra (Indonesia) using the partial mtDNA CO1 gene. Twenty five populations (n = 345) were assayed and subdivided into six regions, following the physiogeographical barriers. Populations Sega (SG), Tanjung Tambutan (TR), Kajang (KJ) and Linggi (LG) are highly diversified (Hd: 0.484–0.762, π: 0.0033–0.0059) which could serve as candidates for a selective breeding programme. The only population that contributed to the total allelic richness is Takengon (CS) as it is highly differentiated from other populations and genetically variable within population. We detected two major phylogenies: 1) northwest Peninsular Malaysia and 2) all other regions of Malaysia and Sumatra, Indonesia. They are products of the physical restriction to gene flow between the two lineages by the Bintang Mountain Range. A total of 92.4% of the population pairwise comparison FST showed significant structuring, yet several geographically distant populations showed a close genetic relationship. The discrepancy is due to ancient population dispersal and human-mediated translocation. These major findings provide an important base study for initiating a selective breeding program. The high population genetic diversity requires independent conservation as they contain most of the total diversity in this area.

Previous studies have suggested that a specific community of bacteria coexists within the phycosphere of marine dinoflagellates. In order to better understand the dinoflagellate-bacteria relationships, a fosmid clone library was constructed from the metagenome DNA and analyzed. Some of the fosmid clones were end-sequenced. A total of 1501 fosmid clones with insert sizes of 30–40 Kbp were produced. End sequencing of 238 clones showed that 55% of the genes had known functions, 11% were of putative function and 34% were genes of unknown function or had no match in Genbank. There were approximately 14% sequences with no classification and could potentially represent novel genes. Analysis of these partial sequences also revealed some promising enzymes that possess various potential industrial applications such as chitinases, kinases, agarases and oxygenases. The results also showed that the bacterial flora of the Alexandrium tamiyavanichii culture was dominated by the Alpha-proteobacteria, followed by Bacteroidetes and Gamma-proteobacteria. The findings in this study suggested that the bacterial community may play various role in the association with dinoflagellate. This study had also shown that dinoflagellate-associated bacterial community is a valuable source for discovery of novel genes and gene products.