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Increasing seawater temperatures coupled with more intense and frequent heatwaves pose an increasing threat to marine species. In this study, the New Zealand green-lipped mussel, Perna canaliculus , was used to investigate the effect of genetics and ontogeny on thermal resilience. The culturally and economically significant mussel P. canaliculus (Gmelin, 1971) has been selectively-bred in New Zealand for two decades, making it a unique biological resource to investigate genetic interactions in a temperate bivalve species. Six selectively-bred full sibling families and four different ages, from early juveniles (6, 8, 10 weeks post-fertilisation) to sub-adults (52 weeks post-fertilisation), were used for experimentation. At each age, each family was exposed to a three-hour heat challenge, followed by recovery, and survival assessments. The shell lengths of live and dead juvenile mussels were also measured. Gill tissue samples from sub-adults were collected after the thermal challenge to quantify the 70 kDa heat shock protein gene ( hsp70 ). Results showed that genetics, ontogeny and size influence thermal resilience in P. canaliculus , with LT 50 values ranging between 31.3 and 34.4 °C for all studied families and ages. Juveniles showed greater thermotolerance compared to sub-adults, while the largest individuals within each family/age class tended to be more heat sensitive than their siblings. Sub-adults differentially upregulated hsp70 in a pattern that correlated with net family survival following heat challenge, reinforcing the perceived role of inducible HSP70 protein in molluscs. This study provides insights into the complex interactions of age and genotype in determining heat tolerance of a key mussel species. As marine temperatures increase, equally complex selection pressure responses may therefore occur. Future research should focus on transcriptomic and genomic approaches for key species such as P. canaliculus to further understand and predict the effect of genetic variation and ontogeny on their survival in the context of climate change.

Mussels, which occupy important positions in marine ecosystems, attach tightly to underwater substrates using a proteinaceous holdfast known as the byssus, which is tough, durable, and resistant to enzymatic degradation. Although various byssal proteins have been identified, the mechanisms by which it achieves such durability are unknown. Here we report comprehensive identification of genes involved in byssus formation through whole-genome and foot-specific transcriptomic analyses of the green mussel, Perna viridis . Interestingly, proteins encoded by highly expressed genes include proteinase inhibitors and defense proteins, including lysozyme and lectins, in addition to structural proteins and protein modification enzymes that probably catalyze polymerization and insolubilization. This assemblage of structural and protective molecules constitutes a multi-pronged strategy to render the byssus highly resistant to environmental insults.

Oceanographic features shape the distributional and genetic patterns of marine species by interrupting or promoting connections among populations. Although general patterns commonly arise, distributional ranges and genetic structure are species-specific and do not always comply with the expected trends. By applying a multimarker genetic approach combined with Lagrangian particle simulations (LPS) we tested the hypothesis that oceanographic features along northeastern Atlantic and Mediterranean shores influence dispersal potential and genetic structure of the intertidal mussel Perna perna. Additionally, by performing environmental niche modelling we assessed the potential and realized niche of P. perna along its entire native distributional range and the environmental factors that best explain its realized distribution. Perna perna showed evidence of panmixia across > 4,000 km despite several oceanographic breaking points detected by LPS. This is probably the result of a combination of life history traits, continuous habitat availability and stepping-stone dynamics. Moreover, the niche modelling framework depicted minimum sea surface temperatures (SST) as the major factor shaping P. perna distributional range limits along its native areas. Forthcoming warming SST is expected to further change these limits and allow the species to expand its range polewards though this may be accompanied by retreat from warmer areas.

The ‘Abundant-Centre Hypothesis’ is a well-established but controversial hypothesis stating that the abundance of a species is highest at the centre of its range and decreases towards the edges, where conditions are unfavourable. As genetic diversity depends on population size, edge populations are expected to show lower intra-population genetic diversity than core populations, while showing high inter-population genetic divergence. Here, the genetic implications of the Abundant-Centre Hypothesis were tested on two coastal mussels from South Africa that disperse by means of planktonic larvae, the native Perna perna and the invasive Mytilus galloprovincialis . Genetic structure was found within P . perna , which, together with evidence from Lagrangian particle simulations, points to significant reductions in gene flow between sites. Despite this, the expected diversity pattern between centre and edge populations was not found for either species. We conclude that the genetic predictions of the Abundant-Centre Hypothesis are unlikely to be met by high-dispersal species with large population sizes, and may only become evident in species with much lower levels of connectivity.

Mussels, particularly Indian brown mussels ( Perna perna L.), have great ecological and economic value due to their restricted distribution along the Indian coastline. They are ideal model organisms for various study domains such as climate change adaptability, biomonitoring, biomaterials, bioadhesion, biofouling, and antifouling. However, there is a noticeable scarcity of genetic information about this species. There is no previous transcriptomic study of the Indian brown mussel. This study used a de novo transcriptomic technique to generate a mussel foot-specific transcriptome for P. perna using 31.72 million high-quality Illumina paired-end reads. A total of 33,567 unigenes were generated, and 18,951 coding sequences (CDS) were predicted. We identified several gene families and key functional genes, including Cytochrome P450 ( CYP2 , CYP1 , CYP3, CYP4 ), Heat-shock proteins ( HSP-70, HSP-90 ), Superoxide dismutase ( SOD ), Catalase ( CAT ), Glutathione-S transferase ( GST ), Toll-like receptors ( TLR-13, TLR-8, TLR-7 ), Aquaporins ( AQP-4, AQP-8 ), growth factor ( IGF ), Glutathione peroxidase, Acetylcholinesterase ( AchE ), Hypoxia-inducible factor-2 and proteins and enzymes involved in bio-adhesion. Our current study serves as a platform for future functional and comparative transcriptomics studies.

The Byssus, which is derived from the foot gland of mussels, has been proved to bind heavy metals effectively, but few studies have focused on the molecular mechanisms behind the accumulation of heavy metals by the byssus. In this study, we integrated high-throughput transcriptome and proteome sequencing to construct a comprehensive protein database for the byssus of Chinese green mussel (Perna viridis), aiming at providing novel insights into the molecular mechanisms by which the byssus binds to heavy metals. Illumina transcriptome sequencing generated a total of 55,670,668 reads. After filtration, we obtained 53,047,718 clean reads and subjected them to de novo assembly using Trinity software. Finally, we annotated 73,264 unigenes and predicted a total of 34,298 protein coding sequences. Moreover, byssal samples were analyzed by proteome sequencing, with the translated protein database from the foot transcriptome as the reference for further prediction of byssal proteins. We eventually determined 187 protein sequences in the byssus, of which 181 proteins are reported for the first time. Interestingly, we observed that many of these byssal proteins are rich in histidine or cysteine residues, which may contribute to the byssal accumulation of heavy metals. Finally, we picked one representative protein, Pvfp-5-1, for recombinant protein synthesis and experimental verification of its efficient binding to cadmium (Cd2+) ions.

The trace elemental composition of biogenic calcium carbonate (CaCO 3 ) structures is thought to reflect environmental conditions at their time of formation. As CaCO 3 structures such as shell are deposited incrementally, sequential analysis of these structures allows reconstructions of animal movements. However, variation driven by genetics or ontogeny may interact with the environment to influence CaCO 3 composition. This study examined how genetics, ontogeny, and the environment influence shell composition of the bivalve Perna canaliculus . We cultured genetically distinct families at two sites in situ and in the laboratory. Analyses were performed on shell formed immediately prior to harvest on all animals as well as on shell formed early in life only on animals grown in the laboratory. Discriminant analysis using 8 elements (Co, Ti, Li, Sr, Mn, Ba, Mg, Pb, Ci, Ni) classified 80% of individuals grown in situ to their family and 92% to growth site. Generalised linear models showed genetics influenced all elements, and ontogeny affected seven of eight elements. This demonstrates that although genetics and ontogeny influence shell composition, environmental factors dominate. The location at which shell material formed can be identified if environmental differences exist. Where no environmental differences exist, genetically isolated populations can still be identified.

Some marine organisms can resist to aqueous tidal environments and adhere tightly on wet surface. This behavior has raised increasing attention for potential applications in medicine, biomaterials, and tissue engineering. In mussels, adhesive forces to the rock are the resultant of proteinic fibrous formations called byssus. We present the solution structure of Pvfp-5β, one of the three byssal plaque proteins secreted by the Asian green mussel Perna viridis , and the component responsible for initiating interactions with the substrate. We demonstrate that Pvfp-5β has a stably folded structure in agreement with the presence in the sequence of two EGF motifs. The structure is highly rigid except for a few residues affected by slow local motions in the µs-ms time scale, and differs from the model calculated by artificial intelligence methods for the relative orientation of the EGF modules, which is something where computational methods still underperform. We also show that Pvfp-5β is able to coacervate even with no DOPA modification, giving thus insights both for understanding the adhesion mechanism of adhesive mussel proteins, and developing of biomaterials. Solution structure of byssal plaque protein Pvfp-5β secreted by the Asian green mussel Perna viridis gives molecular insight into mussel adhesion on wet surfaces.

Perna viridis (Linnaeus, 1758), the Asian green mussel, belonging to the family Mytilidae is widely distributed along the Indian coast. The species is majorly found in southeastern countries and is considered an ideal candidate for aquaculture due to its high nutritional value and growth rate. Obtaining their genetic information is essential for their sustainable capture-based production. In the present study, genetic variation, population structure, and demographic processes of the populations across the distribution of this species were assessed using the mitochondrial DNA ATPase6 and cytb gene. In total, we selected 170 samples from five localities across the Indian subcontinent including Andaman Sea. Sequence analysis of partial cytb (885 bp) and ATPase6 (714 bp) genes revealed 45 and 58 haplotypes, respectively. The significant coefficient of genetic differentiation ( F ST : 0.255 for cytb and 0.252 for ATPase6) and analyses of molecular variance indicated three varieties of stocks, namely Arabian Sea, Bay of Bengal, and Andaman Sea. All the populations showed low nucleotide diversity, suggesting severe historical bottleneck events and high haplotype diversity, indicating population expansion. The genetic variation and demographic process reported in this study will form the baseline information for framing policies, which can be adopted while planning stock specific ranching and relaying programmes in the Indian subcontinent with view to enhance and manage the fishery.

Background Perna viridis (Linnaeus, 1758), the Asian green mussel, is native to the Asia-Pacific region. The species is extensively distributed in the Indian subcontinent and is a candidate species for aquaculture in the Southeast Asian region. Availability of genetic information on wild populations is essential for the effective conservation and management of Perna species. The present study assessed the genetic variation and population structure across the distribution range of this species from the Indian peninsula by using microsatellite markers to determine the genetic structuring among the species. Methods A total of 15 microsatellite loci with M13 labeling were used for the genetic characterization of P. viridis along Indian waters. Genotyped data were analyzed using analytical software to determine the genetic stocks and understand the genetic variability across the populations. Results We identified 15 polymorphic markers to understand the genetic stocks and variability across Perna populations. The mean value of the observed heterozygosity (Hobs: 0.741) for all populations was closer to the expected heterozygosity (Hexp: 0.75). The pairwise Fst values between the west and east coasts of India varied significantly, indicating the existence of significant genetic structure between the populations. Conclusions Genetic stock identification using software analysis exhibited two distinct stocks, one along the west coast (Arabian Sea) and another along the east coast (Bay of Bengal). Bottleneck analysis indicated the genetic stability of species in the wild. P. viridis is a commercially vital species in Indian peninsular regions. The present study suggests the adoption of stock-specific relaying programs of the species from Indian waters in future studies.