Project description:Mollusk secretes a periostracum layer prior to the underlying calcified shell. This organic membrane serves as the first line of protection and primary template for shell orchestration. However, the chemical composition and formation mechanism of the periostracum layer is largely unknown. In this study, we applied transcriptomic, proteomics, physical and chemical analysis to unravel the mysteries of the periostracum formation in the green mussel Perna viridis (Linnaeus). Scanning electron microscopy examination and FTIR analysis showed that the periostracum layer was a multilayered organic membrane composed of polysaccharides, lipids and proteins. Interestingly, proteomic study identified components enriched in tyrosine and some enzymes evolved in tyrosine oxidation, indicating that tyrosine oxidation might play an important role in the periostracum formation. Moreover, comparative transcriptomics suggested that tyrosine-rich proteins were intensively synthesize in the periostracum groove. After being secreted, the periostracum proteins were gradually tanned by oxidation in the sea water, and the level of crosslink increased significantly as revealed by the ATR-FTIR. Our present study sheds light on the chemical composition and putative tanning mechanism of the periostracum layer in bivalve mollusk.
Project description:The 3,4-dihydroxyphenyl-l-alanine (Dopa)-containing proteins of mussel byssus play a critical role in wet adhesion and have inspired versatile new synthetic strategies for adhesives and coatings. Apparently, however, not all mussel adhesive proteins are beholden to Dopa chemistry. The cDNA-deduced sequence of Pvfp-1, a highly aromatic and redox active byssal coating protein in the green mussel Perna viridis, suggests that Dopa may be replaced by a post-translational modification of tryptophan. The N-terminal tryptophan-rich domain of Pvfp-1 contains 42 decapeptide repeats with the consensus sequences ATPKPW(1)TAW(2)K and APPPAW(1)TAW(2)K. A small collagen domain (18 Gly-X-Y repeats) is also present. Tandem mass spectrometry of isolated tryptic decapeptides has detected both C(2)-hexosylated tryptophan (W(1)) and C(2)-hexosylated hydroxytryptophan (W(2)), the latter of which is redox active. The UV absorbance spectrum of W(2) is consistent with 7-hydroxytryptophan, which represents an intriguing new theme for bioinspired opportunistic wet adhesion.
Project description:For understanding the structural characteristics and the proteome of Perna shell, the microstructure, polymorph, and protein composition of the adult Perna viridis shell were investigated. The P. viridis shell have two distinct mineral layers, myostracum and nacre, with the same calcium carbonate polymorph of aragonite, determined by scanning electron microscope, Fourier transform infrared spectroscopy, and x-ray crystalline diffraction. Using Illumina sequencing, the mantle transcriptome of P. viridis was investigated and a total of 69,859 unigenes was generated. Using a combined proteomic/transcriptomic approach, a total of 378 shell proteins from P. viridis shell were identified, in which, 132 shell proteins identified with more than two matched unique peptides. Of the 132 shell proteins, 69 are exclusive to the nacre, 12 to the myostracum, and 51 are shared by both. The Myosin-tail domain containing proteins, Filament-like proteins, and Chitin-binding domain containing proteins represent the most abundant molecules. In addition, the shell matrix proteins (SMPs) containing biomineralization-related domains, such as Kunitz, A2M, WAP, EF-hand, PDZ, VWA, Collagen domain, and low complexity regions with abundant certain amino acids, were also identified from P. viridis shell. Collagenase and chitinase degradation can significantly change the morphology of the shell, indicating the important roles of collagen and chitin in the shell formation and the muscle-shell attachment. Our results present for the first time the proteome of P. viridis shell and increase the knowledge of SMPs in this genus.
Project description:Here, 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 of byssal binding to heavy metals.
Project description:Primary objectives: The primary objective is to investigate circulating tumor DNA (ctDNA) via deep sequencing for mutation detection and by whole genome sequencing for copy number analyses before start (baseline) with regorafenib and at defined time points during administration of regorafenib for treatment efficacy in colorectal cancer patients in terms of overall survival (OS).
Primary endpoints: circulating tumor DNA (ctDNA) via deep sequencing for mutation detection and by whole genome sequencing for copy number analyses before start (baseline) with regorafenib and at defined time points during administration of regorafenib for treatment efficacy in colorectal cancer patients in terms of overall survival (OS).
Project description:A multidisciplinary approach was applied to explore deeper knowledge about the reproductive biology and ecology of the green mussel (Perna viridis) by interlinking among ecological factors, ingested gut plankton, gonad fatty acid profile, and reproductive traits. Mussels were collected throughout the year from the coastal region of the Bay of Bengal of Bangladesh, and the histological analysis of 242 mussels revealed five stages of gametogenesis with an annual spawning season from January to April. The gonadosomatic index showed a strong correlation with the water quality parameters, ingested gut plankton groups, and gonadal fatty acids, and also displayed prominent effects of seasonality. In all datasets, we performed principal component analysis in which the first two principal components showed that seasonality explained >65% of the variability, and the multivariate spaces of seasonality corresponded to the gonad development. High salinity, nutrients, chlorophyll a, and plankton abundance in the water column were positively correlated with gonad development and the spawning of mussels. During the development stage, mussel ingested more plankton, particularly Bacillariophyceae and Pyrrophyceae, which were an important source of increased n-3 polyunsaturated fatty acids content in gonads. Furthermore, gonads accumulated more lipids and saturated fatty acids during the mature and spawning stages, which were probably utilized during embryogenesis and early larval development as energy sources and constituents of the cell membrane. This research provides a model toward a better understanding of reproductive biological traits and how these traits are interrelated with the surrounding environmental variables of the green mussel, which would be helpful in marine aquaculture and the sustainable exploitation of the fishery resources.