Delta of Exopalaemon carinicauda: molecular characterization, expression in different tissues and developmental stages, and its SNPs association analysis with development.

BACKGROUND: The Notch signaling pathway plays a significant role in the gene regulatory network of development of vertebrate and invertebrate. However, as a ligand for the Notch signaling pathway, the mechanism of Delta in the development of Exopalaemon carinicauda is still unclear. METHODS AND RESULTS: The Delta's molecular characteristics, tissue distribution and their association with development in E. carinicauda were studied by RACE (rapid amplification of cDNA end), qRT-PCR (quantitative Real-time PCR) and SNP (single nucleotide polymorphism), respectively. The delta in E. carinicauda had a full-length cDNA of 2807 bp and its Delta of 808 amino-acid residue had the highest identity with the Delta of Homarus americanus (identity = 76.63%). Delta had the highest expression in the ovary, and its expression varied with different stages of embryonic, larval, and ovarian development. After delta RNA interference (with a highest interference efficiency of 66% at 24 h), the expression of Notch signaling pathway genes and developmental related genes was significantly reduced, and the ovarian development was significantly delayed. Further study found that there were 4 SNPs (ds1-4) in delta cDNA, of which two (ds2 T1521G caused a mutation Asn422Lys and ds3 G1674A caused a mutation Tyr473Cys in the EGF-like domain) were associated with the development of E. carinicauda. The Gonadosomatic Index (GSI) of the ds2 TT genotypes was 37.28% and 134.60% higher than E. carinicauda of GT and GG genotype respectively (P < 0.05). CONCLUSION: Our research indicated that delta was involved in the development of E. carinicauda and provided new insights for molecular breeding with SNP markers in E. carinicauda.

A novel Bacillus sp. with antagonistic activity against a plant pathogen, Fusarium graminearum, and its potential antagonistic mechanism.

Fusarium head blight (FHB) is a wheat disease caused by the plant pathogen Fusarium graminearum, which leads to crop yield losses and agricultural economic losses, as well as poses a threat to the environment and human health. Effective biocontrol of F. graminearum is urgent. An antagonistic strain HZ-5 with 59.2% antagonistic activity against F. graminearum in vitro had been isolated from sea mud of Haizhou Bay using a dual-culture assay, which was highly homologous with Bacillus halosaccharovorans according to the 16S rRNA sequence. The antagonistic activity of HZ-5 had been further studied. HZ-5 had a broad range of antagonistic activity against another six plant pathogenic fungi and was effective in controlling FHB of wheat in pot experiment. The substances with antagonistic activity were temperature insensitive, and had been purified by HPLC (High Performance Liquid Chromatography) to prove to be secreted lipopeptides. The antagonistic substances induced the biosynthesis of chitin and glycerol, while ergosterol , cholesterol, and phosphatidylcholine reduced their inhibitory effects on F. graminearum. These data would be helpful to provide a better biocontrol strain against FHB, and to provide important basis to elucidate the antagonistic mechanism of biocontrol.

Genomic organization and promoter analysis of a transcriptional repressor gene from Fenneropenaeus chinensis.

In this study, we cloned and sequenced genomic sequences from a Fenneropenaeus chinensis transcriptional repressor gene, FcTR. The FcTR gene is 2,671 bp in length and has four exons and three introns. The 873 bp promoter contains several transcription factor binding sites, including a TATA box and a cyclic AMP-responsive element. Promoter deletion analysis using a luciferase reporter gene identified regulatory elements. Challenge with white spot syndrome virus increased expression from the promoter-deletion constructs. These results suggest that FcTR might play an important role in the shrimp immune response.

Identification of sex-linked DNA markers by AFLP in Portunus trituberculatus.

To investigate the mechanism of sex determination of crabs, amplified fragment-length polymorphism DNA analysis was applied to identify sex-specific markers for Portunus trituberculatus. Eleven pairs of primers were used to amplify DNA isolated from male and female crabs. A total of 481 and 499 fragments were amplified for females and males, respectively, and the ratios of polymorphic fragments were 20.59-65.52% and 27.27-62.22%, respectively. Distribution difference values between female and male groups for 10 polymorphisms were greater than 40%; Cluster analysis revealed that Nei's genetic distances for 57 polymorphisms clustered according to sex. The results indicate that a difference at the DNA level exists between female and male crabs and provide data for further study on sex determination.