Redtail catfish

Abstract: Sex-specific markers provide significant molecular basis for sex control breeding biotechnology to produce all-male or all-female fish in commercial breeding. Redtail catfish (Mystus wyckioides), one of the commercial bagrid catfishes distributed in Southeast Asian, which have a long sexual maturation period that can last 3-5 years and males have apparent growth advantage over females, but its sex determination system remains unknown. In this study, we first applied 2b-RAD-seq approach to identify three male-specific 2b-RAD-tags and one male heterogametic SNP locus and validated by blast to the genome survey sequences and PCR amplification in both wild and breeding populations. To get longer sex-specific region, we performed genome walking and obtained a 4,630 bp of Y-specific sequence and 4,581 bp of X-specific sequence from the 2b-RAD-tag ref189950 with 92.19% nucleotide identity between them. And 9,923 bp/3,935 bp of Y-specific sequences and 8,491 bp/5,172 bp of X-specific sequences were also identified with 77.49% and 57.07% nucleotide identity in ref208528 and ref210837, respectively. Subsequently, three different kinds of sex-specific primers with different length products were designed based on the detected highly sex differentiated regions and could be used to distinguish males and females both in wild and artificially bred populations. What is more, the X-specific fragment was discovered to produce the dosage effect association in females and in males. The data suggest that male heterogametic XX/XY sex determination system should exist in the redtail catfish. More significantly, the sex-specific markers are of great value to protect wild resources and improve the efficiency of all-male breeding practices for aquaculture in the redtail catfish.

Abstract: Ictalurid catfishes (Siluriformes) in North America harbor proteocephalid tapeworms of the subfamily Corallobothriinae. Type species of 2 of 3 genera of these tapeworms from ictalurids are redescribed, based on museum and newly collected material. Essexiella fimbriata (Essex, 1928) is typified mainly by a wide, umbrella-shaped scolex with a metascolex formed by numerous folds of tissue, anteriorly directed suckers without sphincters, vitellarium bent inwards posteriorly, "flower-shaped" uterus (with anterior, lateral, and posterior diverticula), and a conspicuously pre-equatorial genital atrium. Verified host records of this cestode are only from 3 species of Ictalurus Rafinesque, 1820. Megathylacoides giganteum (Essex, 1928), which seems to be specific to the channel catfish (Ictalurus punctatus), possesses a globular scolex, with a weakly developed metascolex formed by tissue folds posterior to the suckers, anterolaterally directed suckers with large semilunar sphincters, proglottids that are widest at the level of the genital atrium at the anterior third of the proglottid, and uterine diverticula that do not reach the vitelline follicles laterally. A new subfamily, Essexiellinae Scholz and Barcak, is proposed to accommodate species of EssexiellaScholz, de Chambrier, Mariaux and Kuchta, 2011 (type genus), MegathylacoidesJones, Kerley and Sneed, 1956, and CorallotaeniaFreze, 1965 from ictalurid catfishes in the Nearctic Region. These tapeworms possess a metascolex, medullary genital organs, uterus lined with numerous chromophilic cells, pre-equatorial genital atrium, and uterine development of type 2. The new subfamily was monophyletic in all molecular phylogenetic analyses, being most closely related to 3 Neotropical proteocephalids from the redtail catfish, Phractocephalus hemioliopterus (Bloch and Schneider, 1801), but distant from all remaining proteocephalid tapeworms from freshwater fishes in North America.

Abstract: Gelatins from the skin of four different species of fresh water fish, namely pangas catfish (Pangasius pangasius), Asian redtail catfish ( Hemibagrus nemurus), striped snakehead (Channa Striata), and Nile tilapia (Oreochromis niloticus) have been successfully extracted by citric acid. The gelatin from pangas catfish was found to possessed the highest rheology properties compared to the others. It had the following properties: gel strength of 273.58 g, viscosity of 36.5 cP, melting point at 32 o C, gelling temperature at 12 o C, melting temperature at 29 o C and total amino acid content of 754.47 mg/g. The gelatin from fresh water fish had lower physicochemical and rheological properties compared to the commercial gelatin, though total amino acid were 699.86 mg/g for pangas catfish and 734.94 mg/g for striped snakehead, respectively. The fishes investigated in this study were potential alternative sources of gelatin.

Abstract: Asian Redtail Catfish (Hemibagrus nemurus) is highly economic important catfish in South Sumatra. Investigating DNA authentication is of importance for species conservation and breeding selection. Cytochrome C Oxidase subunit I is one of mitochondrial DNA markers used for species barcoding in freshwater, brackishwater and marine fish. This research aims to explore the use of COI gene for species barcoding, constructing phylogenetic tree of Asian Redtail Catfish (ARC). The methods used in the research consisted of DNA extraction, PCR (Polymerase Chain Reaction) amplification and sequencing mtDNA COI gene of ARC obtained from Musi and Penukal Rivers (South Sumatra). A 572 and 596 base pairs of partial coding sequences were obtained representing each river. Phylogenetic analyses indicated that ARC was at the same cluster from Bagridae family, and different cluster from others catfish, Pangasius sp and Oreochomis niloticus. Further study using more species of Bagridae and habitat are needed to investigate the diversity of DNA from South Sumatra water resources