SUMMARY
Background: Molluscs can accumulate carotenoids in their body tissues by predominantly feeding on aquatic
plant sources. Carotenoid transport and absorption are determined by the regulation of various proteins such
as Scavenger receptor class B(SR-BI). We report the identification and characterisation of pearl oyster Pinctada
fuctada martensii SR-BI (PmSR-BI). The correlation between total carotenoid content (TCC) and gene expression
was also estimated.
Results: The full-length cDNA of PmSR-BI was 1828 bp, including an open-reading frame encoding of 1518 bp with
a pI value of 5.83. PmSR-BI protein contains a hydrophobic CD36 domain and four centrally clustered cysteine
residues for the arrangement of disulphide bridges. The deduced amino acid sequence had an identity of 30%
to 60% with the SR-B of other organisms. Reverse transcription polymerase chain reaction analysis showed
that mRNA transcripts were expressed in multiple tissues of adult pearl oyster. A higher expression of PmSR-BI
gene was observed in the hepatopancreas than in the adductor muscle, gill and mantle. The TCC and gene
expression of PmSR-BI were significantly correlated (P b 0.05), with a correlation coefficient of 0.978.
Conclusions: The results suggested that PmSR-BI is involved in the absorption of carotenoids in the pearl oyster
P. fuctada martensii.