Project description:BackgroundThe laminin receptors (LRs) play important roles in cell adhesion to the extracellular matrix, certain cell-cell adhesions, and the activation of many intracellular signaling pathways. Studies of LRs have primarily focused on mammals, while few studies of LRs in marine invertebrates have been reported. The functions of LRs in marine bivalve species are still unclear.Methodology/principal findingsIn this study, we cloned and sequenced an LR gene, MmeLR, from the clam Meretrix meretrix. The MmeLR mRNA and protein detected by realtime PCR and western blots were primarily distributed in muscle tissues. Far-western analysis showed a specific interaction between recombinant MmeLR and the LR ligand laminin. The results of the binding assay suggested a role of LR in cell adhesion and apoptosis in cultured primary cells of mantle tissues from M. meretrix. The Bcl-2 mRNA expression level in primary cells cultured in matrigel (mainly laminin) coated plates was significantly higher than in cells cultured in non-coated plates at 48 h of culture, while the p53 mRNA expression pattern was inversely related to that of bcl-2, suggesting that MmeLR is involved in p53-dependent apoptosis, and the binding between MmeLR and laminin inhibits apoptosis during primary cell culture.ConclusionsOur results suggest that MmeLR may be involved in cell adhesion and apoptosis. This study may increase the understanding of the role of laminin receptor in cell adhesion and apoptosis and help to improve the culture of primary cells of marine invertebrates.
Project description:Bivalve mitochondrial genomes show many uncommon features, like additional genes, high rates of gene rearrangement, high A-T content. Moreover, Doubly Uniparental Inheritance (DUI) is a distinctive inheritance mechanism allowing some bivalves to maintain and transmit two separate sex-linked mitochondrial genomes. Many bivalve mitochondrial features, such as gene extensions or additional ORFs, have been proposed to be related to DUI but, up to now, this topic is far from being understood. Several species are known to show this unusual organelle inheritance but, being widespread only among Unionidae and Mytilidae, DUI distribution is unclear. We sequenced and characterized the complete female- (F) and male-transmitted (M) mitochondrial genomes of Meretrix lamarckii, which, in fact, is the second species of the family Veneridae where DUI has been demonstrated so far. The two mitochondrial genomes are comparable in length and show roughly the same gene content and order, except for three additional tRNAs found in the M one. The two sex-linked genomes show an average nucleotide divergence of 16%. A 100-aminoacid insertion in M. lamarckii M-cox2 gene was found; moreover, additional ORFs have been found in both F and M Long Unassigned Regions of M. lamarckii. Even if no direct involvement in DUI process has been demonstrated so far, the finding of cox2 insertions and supernumerary ORFs in M. lamarckii both strengthens this hypothesis and widens the taxonomical distribution of such unusual features. Finally, the analysis of inter-sex genetic variability shows that DUI species form two separate clusters, namely Unionidae and Mytilidae+Veneridae; this dichotomy is probably due to different DUI regimes acting on separate taxa.
Project description:The Asian hard clam, Meretrix petechialis, is an economically important bivalve, but its catch and population sizes are decreasing rapidly, owing to many factors, including large-scale reclamation of its natural habitat on the western coast of the Korean peninsula. Attempts to restore the resources and production of this species require genetic structure and diversity information. In this study, we developed 15 microsatellite markers from a partial genomic library enriched in GT repeats. Nine of these markers were polymorphic, with an average allele number of six, and six were monomorphic in 95 tested individuals. No linkage disequilibrium was found between any pair of loci (p > 0.05), and deviations from the Hardy-Weinberg equilibrium (HWE) test showing excess of heterozygotes was observed in only one of nine loci. In addition, no null alleles or genetic differentiation between two tested populations were detected. A cross-species amplification in 12 species of four families resulted in two M. petechialis-specific loci and three possible universal markers. This information will be useful in the future development of high-quality artificial seedlings and sustainable resource management.