Yunyan Guan

Molecular characterization of interferon regulatory factor 2 (IRF-2) homolog in pearl oyster Pinctada fucata.

Interferon regulatory factors (IRFs) control many facets of the innate and adaptive immune responses, regulate the development of the immune system itself and involve in reproduction and morphogenesis. In the present study, the IRF-2 homology gene, PfIRF-2 from pearl oyster Pinctada fucata was cloned and its genomic structure and promoter were analyzed. PfIRF-2 encodes a putative protein of 350 amino acids, and contains a highly conserved N-terminal DNA-binding domain and a variable C-terminal regulatory domain. Comparison and phylogenetic analysis revealed that PfIRF-2 shared a relatively higher identity with other mollusk but relatively lower identity with vertebrate IRF-2, and was clustered with IRF-1 subfamily composed of IRF-2 and IRF-1. Furthermore, gene expression analysis revealed that PfIRF-2 involved in the immune response to LPS and poly(I:C) stimulation. Immunofluorescence assay showed that the expressed PfIRF-2 was translocated into the nucleus and dual-luciferase reporter assays indicated that PfIRF-2 could involved and activate interferon signaling or NF-κB signal pathway in HEK293 cells. The study of PfIRF-2 may help better understand the innate immune in mollusk.

Molecular cloning, characterization and expression analysis of tumor necrosis factor receptor-associated factor 3 (TRAF3) from pearl oyster Pinctada fucata.

TRAF3 is a highly versatile regulator that negatively regulates JNK and alternative nuclear factor-κB signalling, but positively controls type I interferon production. To investigate TRAF3 function in innate immune responses among invertebrate especially mollusk, we characterized TRAF3 (PfTRAF3) from pearl oyster Pinctada fucata, one of the most important bivalve mollusks for seawater pearl production. PfTRAF3 cDNA is 2261 bp with an open reading frame of 1623 bp encoding a putative protein of 541 amino acids. The deduced PfTRAF3 contains a RING finger domain, two TRAF domains with zinc finger domains and a conserved C-terminal meprin and TRAF homology (MATH) domain. Comparison and phylogenetic analysis revealed that PfTRAF3 from mollusk shared a higher identity with Ciona intestinalis TRAF3 from urochordata, Branchiostoma belcheri TRAF3 from cephalochordate, and even TRAF3 from vertebrate than with insect homologues. Furthermore, gene expression analyses suggested that PfTRAF3 was involved in the immune response to Vibrio alginolyticus.

Identification of sixteen single-nucleotide polymorphism markers in the pearl oyster, Pinctada fucata, for population genetic structure analysis

The pearl oyster, Pinctada fucata, a marine bivalve belonging to the family Pteriidae, is the primary species cultured for marine pearls in China and Japan (Zhang 2002). To increase the yield, successful techniques for artificial breeding have been established in China (Zhang 2002). However, with increasing acreage for artificial farming, several issues such as declining genetic diversity in culture are being taken into consideration in the modern pearl oyster farming industry. Further study on these topics would require the available genetic tools such as molecular markers (Liu and Cordes 2004). Single-nucleotide polymorphisms (SNPs) are nucleotide variations in the DNA sequence of individuals. As the most abundant molecular markers in the genome, they are sequence-tagged markers with codominant inheritance, and thus are ideal for population genetic studies (Morin et al. 2004). Therefore, in recent years, SNP have been characterized and applied in many aquaculture species such as Salmo salar (Hayes et al. 2007), Crassostrea virginica (Zhang and Guo 2010) and Chlamys farreri (Li et al. 2013). However, to our knowledge, although the draft genome of P. fucata has been established which could provide a platform for the identification of selection markers (Takeuchi et al. 2012), there are no SNP loci which have been identified for the pearl oyster, P. fucata. At present, there are many SNP genotyping systems (Kim and Misra 2007). For our research focussing on developing a limited number of SNP markers for