Gene Editing of the Follicle-Stimulating Hormone Gene to Sterilize Channel Catfish, Ictalurus punctatus, Using a Modified Transcription Activator-like Effector Nuclease Technology with Electroporation.

Follicle-stimulating hormone (fsh) plays an important role in sexual maturation in catfish. Knocking out the fsh gene in the fish zygote should suppress the reproduction of channel catfish (Ictalurus punctatus). In this study, transcription activator-like effector nuclease (TALEN) plasmids targeting the fsh gene were electroporated into fertilized eggs with the standard double electroporation technique. Targeted fsh cleavage efficiency was 63.2% in P1fsh-knockout catfish. Ten of fifteen (66.7%) control pairs spawned, and their eggs had 32.3-74.3% average hatch rates in 2016 and 2017. Without hormone therapy, the spawning rates of P1 mutants ranged from 33.3 to 40.0%, with an average egg hatching rate of 0.75%. After confirmation of the low fertility of P1 mutants in 2016, human chorionic gonadotropin (HCG) hormone therapy improved the spawning rates by 80% for female mutants and 88.9% for male mutants, and the mean hatch rate was 35.0% for F1 embryos, similar to that of the controls (p > 0.05). Polymerase chain reaction (PCR) identification showed no potential TALEN plasmid integration into the P1 channel catfish genome. Neither the P1 nor the F1 mutant fish showed any noticeable changes in in body weight, survival rate, and hatching rate when the reproductive gene was knocked out. F1 families had a mean inheritance rate of 50.3%. The results brought us one step closer to allowing implementation of certain genetic techniques to aquaculture and fisheries management, while essentially eliminating the potential environment risk posed by transgenic, hybrid, and exotic fish as well as domestic fish.

Diallel Cross Application and Histomolecular Characterization: An Attempt to Develop Reference Stock of Labeo ariza.

The objective of the present study was to evaluate the growth performance and genetic variation in diallel crosses of Ariza labeo (Labeo ariza) originating from three geographically separated rivers (Atrai, Jamuna and Kangsha) in Bangladesh. Intra (G1K♀K♂, G2J♀J♂, and G3A♀A♂) and inter (G4K♀A♂, G5K♀J♂, G6A♀K♂, G7A♀J♂, G8J♀K♂, and G9J♀A♂) stocks were produced following diallel cross (sex ratio-1:1 and n = 48; 16 from each river). Reproductive and growth performance, muscle cellularity and genetic variation following genotyping of eight microsatellite markers (Lr1, Lr2, Lr3, Lr22, Lr24, Lr27, Lr28 and Lr29) and analysis of all crossbreeds was performed. The fertilization (95% ± 2.11%), hatching (88% ± 1.03%), and survival rates (82% ± 1.88%) of G4K♀A♂ were higher compared to other groups. With respect to length and weight gains (2.67 ± 0.4 cm and 3.39 ± 0.2 g), SGR (3.23% ± 0.20%), and heterosis (8.87% and 24.74%) G4K♀A♂ was the superior group. A higher number of hyperplastic muscle fibers, mean number of alleles (2.75) and mean observed heterozygosity (0.417) from G4K♀A♂ could be interpreted to mean that G4K♀A♂ comprise better performance efficiency compared to others and are considered for continuing the L. ariza stock improvement program.

First draft genome assembly and identification of SNPs from hilsa shad ( Tenualosa ilisha) of the Bay of Bengal.

Background: Hilsa shad ( Tenualosa ilisha), a widely distributed migratory fish, contributes substantially to the economy of Bangladesh. The harvest of hilsa from inland waters has been fluctuating due to anthropological and climate change-induced degradation of the riverine habitats.  The whole genome sequence of this valuable fish could provide genomic tools for sustainable harvest, conservation and productivity cycle maintenance. Here, we report the first draft genome of  T. ilisha from the Bay of Bengal, the largest reservoir of the migratory fish. Methods: A live specimen of T. ilisha was collected from the Bay of Bengal. The whole genome sequencing was performed by the Illumina HiSeqX platform (2 × 150 paired end configuration). We assembled the short reads using SOAPdenovo2 genome assembler and predicted protein coding genes by AUGUSTUS. The completeness of the T. ilisha genome assembly was evaluated by BUSCO (Benchmarking Universal Single Copy Orthologs). We identified single nucleotide polymorphisms (SNPs) by calling them directly from unassembled sequence reads using discoSnp++. Results: We assembled the draft genome of 710.28 Mb having an N50 scaffold length of 64157 bp and GC content of 42.95%. A total of 37,450 protein coding genes were predicted of which 29,339 (78.34%) were annotated with other vertebrate genomes. We also identified 792,939 isolated SNPs with transversion:transition ratio of 1:1.8. The BUSCO evaluation showed 78.1% completeness of this genome. Conclusions: The genomic data generated in this study could be used as a reference to identify genes associated with physiological and ecological adaptations, population connectivity, and migration behaviour of this biologically and economically important anadromous fish species of the Clupeidae family.