Blotched snakehead

Abstract: A warm-water fish cell line developed from blotched snakehead caudal peduncle (BSN) was found to have persistent birnavirus infection. Purified virus particles were of icosahedral shape and had 57+/-1.6 nm diameter. The BSN virus was resistant to 5-iodo-2'-deoxyuridine and induced yellowish-green cytoplasmic inclusions when stained with acridine orange. The virus was resistant to chloroform, acid and alkaline pH and heat treatment at 56 degrees C for 2 h. Purified virions had a buoyant density of 1.33 g/ml in CsCl and contained two genomic segments with molecular masses of 2.56 x 10(6) and 2.00 x 10(6) Da and four structural polypeptides of 112 (polyprotein, PP), 91 (VP1), 44 (VP2) and 37 (VP3) kDa. Reciprocal beta cross-neutralization tests incorporating four classical strains of infectious pancreatic necrosis virus (IPNV) (WB, Sp, Ab and TV-1) and the BSN virus established the complete serological distinctness of the virus from IPNV. Considering the uniqueness of the virus, the name blotched snakehead virus is proposed for this agent.

Abstract: Birnaviruses of aquatic organisms constitute small, nonenveloped icosahedral viruses with bisegmented, double-stranded RNA (dsRNA) genomes, and currently, two genera infect aquatic organisms; Aquabirnavirus and Blosnarvirus Among aquabirnaviruses, the infectious pancreatic necrosis virus (IPNV) is the type species and causes severe diseases in salmonids, while there are a number of other aquabirnaviruses that infect other aquatic organisms Blotched snakehead virus is the type strain of the Blosnarvirus genus, infecting blotched snakehead (Channa maculata) The genome of birnaviruses is organized into two segments, A and B Segment A encodes the structural proteins VP2 and VP2 plus the virus protease (VP4) and a nonstructural protein, VP5 Segment B encodes the viral polymerase The virulence traits of IPNV have been well defined, and for strains infecting Atlantic salmon, highly virulent strains carry defined amino acids in defined residues of the VP2 protein Vaccination and selective breeding in Atlantic salmon have contributed to reducing the impact of IPNV infection in salmonid aquaculture worldwide

Abstract: Dmrt1 is an important transcriptional regulator that plays critical role in male gonadogenesis, testicular differentiation and development. In this study, Dmrt1 was cloned from blotched snakehead (Channa maculata), which is designated as CmDmrt1. CmDmrt1 encoded a putative protein with 293 amino acids and presented an extremely conserved DM domain. It was nearly expressed in the gonads, and the expression was more than 15 times higher in the testis than in the ovary. 1851 bp promoter sequence of CmDmrt1 was characterized and the methylation levels of the CpG sites were analyzed to detect sex-related differences. A significant negative correlation between CmDmrt1 expression and CpG methylation level of its promoter was found in the testis and ovary. During gonadal development, CmDmrt1 transcription displayed strong male-biased expression patterns, increased with the maturation of testis and reached the peak at 195 days after hatching (dah), which indicates a significant role of Dmrt1 in spermatogenesis. Steroid treatment could influence CmDmrt1 expression, and long-term 17β-estradiol (E2) treatment could induce the male-to-female secondary sex reversal (SSR), which resulted in the differentiated testis transformed to ovary or ovotestis. Meanwhile, CmDmrt1 expression was down-regulated to fairly low level in the ovary of the SSR XY fish, which was similar to that in normal XX females ovary. Our research illustrates that Dmrt1 is linked to testis differentiation and spermatogenesis in blotched snakehead, providing information for functional studies on sex differentiation and gonadal development of C. maculata, and scientific basis for the production practice of all-male snakehead breeding.