Molecular identification, expression and function analysis of peroxidasin in Chilo suppressalis.

Peroxidasin plays a unique role in the formation and stability of extracellular matrix (ECM) in the animal kingdom; however, it was only characterized in Diptera, not in other insect orders. In this study peroxidasin (CsPxd) was first identified and characterized from Chilo suppressalis, a lepidopteran pest. CsPxd complementary DNA with a 4080 bp open reading frame encodes a peptide of 1359 amino acids; the derived amino acid sequence of CsPxd harbors the typical structural characteristics of peroxidasin family in heme-peroxidase superfamily, including the signal peptide at N-terminal, leucine-rich repeat domain, Ig-loop motifs and peroxidase domain, signifying the extracellular location of protein and the involvement in ECM formation. Eukaryotic expression reveals CsPxd protein displays peroxidase activity on H2 O2 , justifying the membership of peroxidase. Phyletic analysis shows the monophyletic evolution pattern of peroxidasin in insect phyle, and moreover only one peroxidasin is present in each species of insects, suggesting its evolutionary conservation on function. Peroxidasin messenger RNA is mainly expressed in egg and the final instar larvae stage. Injection of peroxidasin double-stranded RNA into the final instar larvae impacts the cuticle sclerotization during the metamorphosis from larvae to pupa, and eventually lead to lethality of larvae and pupa. These results suggest the presence of collagen crosslink in chorion and cuticle of insects, and indicate peroxidasin plays a role in the development of chorion and cuticle; furthermore peroxidasin might be the one of potential target genes for pest control using RNA interference.

[A novel polymorphism of IGFBP-3 gene and its relationship with several wool traits in Chinese Merino sheep].

In this study, PCR-SSCP analysis was used to identify genetic variation in IGFBP-3 gene in Chinese Merino and Kazakh sheep. A PCR product of 178 bp corresponding to partial intron1 illustrated three unique binding patterns by SSCP analysis. Frequencies of the genotype AA, AB, BB and allele A, B in Chinese Merino sheep were 0.70, 0.24, 0.06, and 0.82, 0.18 respectively , and they were 0.87, 0.13, 0.00, and 0.93, 0.07 respectively in Kazaka sheep. Sequence analysis revealed a G/T transversion at position 122 of the fragment. This polymorphic locus of IGFBP-3 gene was at Hardy-Weinberg dis-equilibrium (P<0.01) in the two breeds. Different genotypes slightly affected several wool traits of Chinese Merino sheep. The individuals of genotype AA, AB, and BB had no significant difference in post-shearing weight and clean wool rate. Sta-ple length (SL) was decreased with the genotype of AA, AB, and BB, and the difference between AA and AB was significant (P<0.01). Greasy fleece weight (GFW) and follicle density in individuals of genotype AA was significantly lower than that in individuals of genotype AB (P<0.01) and BB (P<0.05); Average fiber diameter (AFD) in individuals of genotype AA was significantly higher than that in individuals of genotype AB (P<0.01) and BB (P<0.05).