Performing Department
College of Agriculture
Non Technical Summary
In this project, we will knockout the myostatin gene in farmed US catfish, which is a negative growth regulator. In other words, it slows down growth and if we knock it out, increased growth is expected. Also, the number of muscle fibers will increase that may affect texture in a positive way. The US imports many times more seafood products than what we produce, which damages our US economy and our fish farming communities financially. Having genetically improved fish that can improve production and flesh quality could have major effects on farm income as well as other steps in the value chain, helping the US economically as well as making us less dependent on other countries for protein, which in reality is a national security threat. The long-term objective/goal is to genetically improve the overall genotype/phenotype of both channel catfish and the F1 hybrid between channel catfish females and the blue catfish males as sectors of the catfish industry use both. Our expected result is the development of genetically enhanced catfish improved for growth, feed conversion efficiency, texture and disease resistance, impacting and benefitting the hatchery, producer, processor and consumer.
Animal Health Component
10%
Research Effort Categories
Basic
65%
Applied
35%
Developmental
0%
Goals / Objectives
The long-term objective/goal is to genetically improve the overall genotype/phenotype of catfish, both channel catfish, Ictalurus punctatus, and the F1 hybrid between channel catfish females and the blue catfish, I. furcatus males. Among the traits of interest addressed in this proposal are growth, feed conversion efficiency, carcass yield, texture and disease resistance.Our supporting/specific objectives are 1) Produce channel catfish and hybrid catfish gene edited for myostatin and determine their growth, feed conversion efficiency, carcass yield, body composition, texture and disease resistance compared to normal, non-mutated controls, 2) Determine if zygosity affects performance of myostatin gene edited channel catfish and hybrid catfish allowing for the determination of the gene action of the mutation, and 3) Determine the effect of myostatin knock out on the immune gene expression in catfishOur overall long-term goal is pond-to-plate genetic enhancement of catfish: improvement of traits important to hatchery managers, food fish producers, processors and the consumer. The traits addressed in the current proposal focus on fish growers and processors, and their enhancement will indirectly benefit consumers.
Project Methods
Channel catfish and hybrid catfish gene edited for myostatin will be compared to normal, non-mutated controls for growth, feed conversion efficiency, carcass yield, body composition, texture and disease resistance, and the effect of zygosity on performance will be determined. Communally (all families together) together will be conducted in earthen ponds at 25,000 fish/ha. Fish from each gene-edited and control family will be sampled to determine dressout%, fillet%, texture, protein, fat, moisture, muscle fiber size and number of the muscle. By comparing the growth of the controls, heterozygous mutants and homozygous mutants, the gene action; recessive, additive, dominant or incompletely dominant; can be determined for the gene edit. Mutation analysis will be determined with Surveyor Analysis and sequencing. Parallel experiments will be conducted in aquaria to determine feed conversion efficiency.Sensory analysis will be conducted using the protocols of the American Meat Science Association (AMSA) Research Guidelines for Cookery, Sensory Evaluation, and Instrumental Tenderness Measurements of Meat (2nd ed.) (AMSA 2015). All fresh, raw fillets will be scored for color with a colorimeter for whiteness, yellowness and redness. Texture and flavor will be measured. They will be split into 2 sets, one for analysis of fresh, uncooked flesh and one for analysis of cooked product. The properties of the fresh, uncooked fillet are important to the processor to allow cutting the flesh into different products as well as trimming of standard products. For texture analysis of fresh fillets, catfish fillets will be cooked and evaluated for toughness, mushiness, flakiness and fibrousness. Histological analysis will be conducted and the results correlated to the other parameters to determine its potential value as a carcass quality predictor. Muscles fibers will be counted. Cell numbers will be calculated as the number of fibers per cross-sectional muscle area using the "Cell Counter" features of Image J program and used for evaluating fiber sizeOne-month to 4-month-old naïve fish will be challenged with pathogens. Four bacterial challenges and one viral challenge will be conducted in succession. In order, the pathogens tested against the catfish genetic types will be channel catfish virus (CCV), Flavobacterium columnare, Edwardsiella ictaluri, E. pisicida and Aeromonas hydrophila. Gene expression will be determined. Fish will be sampled just prior to death during the challenge, as well as unchallenged controls of each genetic type, and survivors of each genetic type. Trunk kidney, liver, blood, intestine, gill, and skin will be evaluated For all challenges, TLR4/TLR7/8, CD4/CD14, IL-1β/TNFa/tgf-β1, myd88/NF-kB, MHC Class II, CC chemokine SCYA106; the innate AMPs, leap2, hamp; LH, FSH, GnRH, the transgene cathelicidinand GH will be examined for gene expression; and for the CCV challenge IFNg, will be added. Results in 2022 will determine what genes and treatments will be evaluated with qPCR in 2024.Data will be evaluated with a variety, but appropriate tests. We will make presentations at School of Fisheries seminars, scientific conferences, the annual PI meeting, at farmer meetings and keep biotechnology companies informed of our results.