Fig 1.
The photograph of inner surface and the SEM images of cross-section of P. viridis shell.
A: the photograph of inner surface of an adult P. viridis shell. The black dot line represents the cutting plane; “AMS-A”, “AMS”, and “AMS-P” represent the area of anterior side from adductor muscle scar (AMS), central AMS, and the posterior side from AMS, respectively. B: the SEM image of the section of AMS-A. N represents the nacre layer, M represents the myostracum layer; C: the SEM image of the section of central AMS; D: the SEM image of the section of AMS-P. E: the SEM image of the section close to the outside of the shell; F: the SEM image of the section of the outside of the shell. The bar is 10 μm for B, C, D, and E, and 20 μm for F.
Fig 2.
Surface images of AMS and AMS-A region.
A: the inner surface image of natural shell of P. viridis at AMS region with the adductor muscle attached; B: the SEM image of surface of AMS region after the adductor muscle removed. The pit structures are denoted by arrows; C: the SEM image of the surface from transition zone between the AMS and AMS-A; D: the SEM image of the surface of AMS-A; E: The SEM image of the AMS surface after deproteinization; F: The SEM image of the AMS-A surface after deproteinization.
Fig 3.
FTIR spectra and XRD profiles of the nacre layer and myostracum layer.
A: FTIR spectra of the two layers of P. viridis shell. The single star and the double star indicate the amide I and amide II region, respectively. B: XRD profiles of the two layers of P. viridis shell. The arrows represent the aragonite peaks.
Fig 4.
SEM images of shell cross-section at AMS-A and AMS of P. viridis after collagenases digestion.
A: the section image of AMS-A from the control sample; B: the section image of AMS from the control sample; C: the SEM image of AMS–A section after type-I collagenase digestion; the etched cracks and holes can be seen at the tablet of the nacre layer; D: the SEM image of AMS section after type-I collagenase digestion; the etched area at the myostracum layer are denoted by black arrows; E: the section image of AMS-A from the control sample; F: the section image of AMS from the control sample; G: the SEM image of AMS–A section after type-II collagenase digestion; the etched area at the nacre layer are circled with white dash line and the etched crack of the myostracum layer are denoted by black arrows; H: the SEM image of AMS section after type-II collagenase digestion; the etched area at the nacre layer are denoted by black arrows. The bar is 5 μm.
Fig 5.
SEM images of shell cross-section at AMS-A and AMS of P. viridis after chitinases digestion.
A: the section image of AMS-A from the control sample; B: the section image of AMS from the control sample; C: the SEM image of AMS–A section after chitinase digestion; the etched long cracks at the nacre layer are denoted by arrows; D: the SEM image of AMS section after chitinase digestion; the etched long cracks at the nacre layer are denoted by arrows. E: the section image of AMS-A from the control sample; F: the section image of AMS from the control sample; G: the SEM image of AMS–A section after chitinase digestion; the etched long cracks at the nacre layer are denoted by arrows; H: the SEM image of AMS section after chitinase digestion; the etched long cracks at the nacre layer are denoted by arrows. The bar is 5 μm for A, B, E, F and G, and 10 μm for C, D, and H, respectively.
Fig 6.
SEM images of inner surface at the AMS-A and the AMS area after enzyme digestion.
A: the surface image of AMS-A from control sample; B: the surface image of AMS from control sample; C: the SEM image of AMS–A surface after collagenase digestion; D: the SEM image of AMS surface after collagenase digestion; E: the SEM image of AMS–A surface after chitinase digestion; F: the SEM image of AMS surface after chitinase digestion.
Fig 7.
Gene Ontology annotation of the unigenes from P. viridis mantle transcriptome.
Fig 8.
KOG annotation of the unigenes from P. viridis mantle transcriptome.
Fig 9.
COG annotation of the unigenes from P. viridis mantle transcriptome.
Table 1.
The candidate mantle transcripts involved in biomineralization from P. viridis mantle.
Table 2.
The MS information of the four samples extracted from P. viridis shell.
M-AIS, the acid-insoluble sample from myostracum layer. M-AS, the acid-soluble sample from myostracum layer. N-AIS, the acid-insoluble sample from nacre layer. N-AS, the acid-soluble sample from nacre layer.
Fig 10.
Functionally annotation of the myostracum SMPs identified from P. viridis shell.
A: COG annotation of the SMPs from myostracum layer; B: GO annotation of the SMPs from myostracum layer.
Fig 11.
Functionally annotation of the nacre SMPs identified from P. viridis shell.
A: COG annotation of the SMPs from the nacrelayer; B: GO annotation of the SMPs from the nacre layer.
Table 3.
The top 10 KEGG pathways of the identified proteins from the nacre and the myostracum layer of P. viridis shell.
Table 4.
SMPs identified with more than two matched peptides from the P. viridis shell by LC-MS/MS.
The MS/MS spectra were used for searching against the Illumina-sequencing based P. viridis mantle transcriptome using Mascot software. N represents the nacre layer and M represents the myostracum layer.
Table 5.
Comparison of SMPs with domain features in the shells of various Bivalves.
The “√” indicates identification of this protein in this species.