Acute Toxicity of Four Drugs to Larvae of Channa argus

The acute toxicity of 4 drugs, dipterex, potassium permanganate, copper sulfate and formaldehyde to larvae of black-spot hybrid snakehead was tested with the semi hydrostatic test method under water temperature of （28.3± 1.5）℃, pH of（8.01 ±0.12） and dissolved oxygen of （4.6 ±0.5） mg/L. The results showed that 96 h median-lethal concentration （LCso） of copper sulphate was the lowest, 1. 586 mg/L, while 96 h LC50 of formaldehyde was the highest, 115. 159 mg/L. The toxicity of the 4 drugs ranked in the order of copper sulphate, dipterex, potassium permanganate and formaldehyde from high to low. The safe concentrations（SCs） of the 4 drugs were in order of formaldehyde （35. 529 mg/L）, potassium permanganate （ 1. 277 mg/L）, dipterex （ 1. 450 mg/L） and copper sulphate （0.882 mg/L）. According to the rosults,the SCs of dipterex, formaldehyde and copper sulphate were higher than the conventional dosage, they were safe to be used for control of corresponding diseases of Channa argus by the conventional dosage. The SC of potassium permanganate was in the conventional dosage range, so it could be used for control of diseases in accordance with the SC of C. argus to the drug in production.

Investigation of Phylogenetic Relationship among Three Species of Channa Based on ITS Sequence Analysis

[ Objective ] This study aimed to analyze genetic variation of ribosomal ITS region sequences in Channa argus, C moculata and C. asiatica, and to in- vestigate the phylogenetic relationship among Charma species based on ITS sequences. [ Method] ITS sequences of three Channa species were amplified by PCR, cloned and assembled to obtain the full length of ITS sequences. [ Result] The full length of ITS sequences of C. argus, C. maculata and C. asiatica was 902, 927, and 902/903 bp, respectively. ITS sequences of C. argus, C. maculata and C. asiatica exhibited higher G ＋ C （72%） than A ＋ T. Interspecific nucleotide differences were significantly greater than intraspecific differences of these three Channa species. Thus, these remarkably differential ITS fragments could be used to identify C. argus, C. maculata and C. asiatica. Phylogenetic tree constructed by Neighbor-joining and Maximum Likehood methods showed that C. argus shared the lowest genetic distance with C. maculata and the highest genetic distance with C. asiatica. [ Conclusion] This study provided reference for classification, i- dentification, phylogenetic analysis and interspecific hybridization of Channa species.

Full-length transcriptome sequencing analysis reveals differential skin color regulation in snakeheads fish Channa argus

Albinism is a genetic disorder caused by a series of genetic abnormalities that result in a decrease in melanin.Golden yellow snakehead fish(GCAS)has been discovered while the Channa argus(CAS)breeding,but the genetic mechanism that causes its albinism is not known.Transcriptome sequencing and comparison of CAS and GCAS skin using Oxford Nanopore Technologies(ONT)technology to elucidate the molecular mechanisms of snakehead albinism.27.1 G clean reads and 26,198 full-length non-redundant sequences were generated via ONT sequencing.Overall,8079 new transcripts and 7231 genes were identified by comparing and analyzing redundant removed transcripts and known reference genome annotations.The results of DEGs analysis showed that a total of 59 transcripts were differentially expressed in the two groups,including 22 up-regulated transcripts and 37 down-regulated transcripts.Five causative genes associated with albinism have been identified,including TYR(Tyrosinase)and SOX10(SRY-box transcription factor 10)(tyrosinase synthesis and metabolism),S-100(S100 calcium binding protein A1)(melanin production),NLRC3(NLR family CARD domain containing 3)(disease immunity)are significantly down-regulated in GCAS,while RhoGEFs expression(melanin synthesis)is up-regulated.Protein interaction analysis revealed that GAPDH(Glyceraldehyde-3-phosphate dehydrogenase)is the top hub gene in the regulation of skin color in C.argus.In addition,the skin of snakehead fish is regulated by metabolic(GAPDH),immune[Tumor protein p53(TP53),C-X-C motif chemokine ligand 8(CXCL8),SRC proto-oncogene,non-receptor tyrosine kinase(SRC),CD274]and neural[Notch receptor 1(NOTCH1),C-X-C motif chemokine ligand 12(CXCL12)]related genes to achieve differences in skin color.These findings in understanding the process by which albinism in fish develops.