2008 Annual Report
(1) Animal holding facilities: One experimental recirculating fish-holding system was designed and set up with 12 x 30-ft gallon tanks, a sump system, mechanical filters, chemical filters, UV sterilizer, degassing tower and a ½ hp chiller. Also, two separate flow-through systems were designed and set up. They consist of 8 x 15-ft gallon tanks, a header tank with a 1500W heater, degassing column, feeders, lights, aeration, and an activated carbon sump for studies utilizing steroids. Lastly, 4 x 6-ft diameter tanks were set up for holding animals under flow-through conditions. (2) Completed animal studies: Three studies were undertaken to examine the control of genes involved with growth of yellow perch. Study 1-- this study simply involved a fasting (5-week) versus feeding study in adult yellow perch. After 5 weeks, tissues (brain, pituitary, gill, liver, kidney, head kidney, stomach, skin, muscle and plasma) were sampled to examine the expression of genes involved with growth. Study 2 -- Immature animals were fed a diet with 15 mg/kg of estrogen or an untreated diet. Lengths and weights were collected every two weeks for 12 weeks, and then sampled for tissues as above. Dietary estrogen treatment significantly increased weight and length yellow perch at all time points. Study 3 -- this study involved the time-course effects of lipopolysaccharide (LPS: stimulates the immune response) in yellow perch. Our aim is to understand common molecular pathways involved with growth and immunity. Equal numbers of male and female yellow perch were injected with 10 micrograms/gram body weight LPS or saline (control), and sampled at 3, 6, 12, 24, 48, and 72 hours after injection and tissues collected as above. (3) Characterize genes involved with growth and immunity: In yellow perch, GH does not stimulate growth, which suggests a condition of GH insensitivity. We hypothesize that the estrogen-dependent growth seen in yellow perch may be a causal factor underlying GH insensitivity and that any genetic gain in growth may be offset by decreases in immunity. We have cloned genes which encode for a family of proteins that regulate the signaling of hormones that control growth and immunity. We have cloned other growth-regulating genes including prolactin, growth hormone, somatolactin, insulin-like growth factor-I, the estrogen receptors (alpha and beta), aromatase, and myostatin 1 & 2. We are isolating ribonucleic acid (RNA) from the tissues of animals from the described studies, and the expression patterns, and control, of these genes will be examined.
This work addresses the following components in the NP-106 action plan: Genetic Improvement parts C (Selective Breeding for Economically-Important Traits) and D (Development of Genomics Resources); Integrated Aquatic Animal Health part C (immunology and Disease Resistance); and Growth and Development, and Nutrition part b (Tissue Growth and Development).
1)slow growth to market size (~14-16 months) and small size at harvest. Physiologically, yellow perch display an estrogen-dependent, sexually-dimorphic growth rate where females grow faster, and larger, than males which pose concerns for a selective breeding program. Additionally, growth hormone (GH) does not appear to stimulate growth which suggests a condition of GH insensitivity. We hypothesize that the estrogen-dependent growth seen in yellow perch may be a causal factor underlying GH insensitivity and that any genetic gain in growth (due to selection) may be offset by decreases in immunity. Consequently, we have characterized and published sequences for the growth-regulating hormones in yellow perch. These hormones include pituitary hormones, growth hormone (GH), prolactin (PRL) and somatolactin (SL), their associated growth factors (insulin-like growth factors: IGF-I, IGF-II), and steroid receptors (estrogen receptors) and a steroidogenic enzyme (aromatase). An understanding of the hormonal pathways responsible for estrogen-dependent growth in yellow perch will provide unprecedented insights into how female sex steroids promote growth in this species as well as developing ways to manipulate and select for more uniform growth among the sexes. Such an understanding will be essential to selecting for improved growth in this species while, potentially, minimizing any deleterious effects on other important phenotypic traits such as sexual maturation and immunity. (National Program 106, Action Plan Component: Growth and Development, and Nutrition, part b -- Tissue Growth and Development). 4. Develop methods to alter timing of reproductive development (yellow perch). Photothermal regimes were used to develop out-of-cycle spawning perch broodstocks. Gametes were collected & artificially fertilized from wild broodstock in 3/2007. These eggs produced a F1 generation that was manipulated photothermally to become a July spawning broodstock & subsequently transferred to private industry. Gametes were collected & artificially fertilized from wild broodstock of the Sassafras River (MD) in 3/2003. These eggs produced an F1 generation that was manipulated photothermally to become a January spawning broodstock. F1 broodstock egg production was: normal spawners, 7,525,000 (2005), 6,320,000 (2006),16,435,000 (2007) &14,400,000 (2008); Out-of-cycle spawners: 5,805,000 (2005), 9,985,000 (2006), 23,665,000 (2007) & 22,800,000 (2008). Jan 2007 eggs resulted in F2 fingerlings that were photothermally conditioned to become January spawning broodstock (2009-2010). Fingerlings produced from the Jan spawning of the Sassafras River strain in 2006 were raised for 14 months in a recirculating aquaculture system (RAS) at constant temperature between 20-22 degrees C. Adult fish were selected to become additional broodstock, & manipulated photothermally to spawn in Oct 2007. These fish produced 11 million eggs to make a F3 generation. The history of this F3 generation is: great-grandparents were wild March spawners, grandparents were captive January spawners, & parents were captive Oct 2007 spawners. These F3 generation perch were evaluated for the timing of first-feeding, general behavior, early mortality syndrome, & transition to a commercial diet. These techniques will be used to induce maturity of the F1 generation (National Program 106, Action Plan Component: Genetic Improvement, part d -- Specific Breeding Aids; Plan Component: Reproduction and Early Development, part a -- Control of Reproduction).
5.Significant Activities that Support Special Target Populations
“Improving Growth in Finfish: Approaches and Mechanisms”. U.S. Trout Farmers Association meeting, September 18-20, Hilton Milwaukee Center, Milwaukee, WI. Oral presentation.
USDA-ARS, NP-106 (Aquaculture) National Stakeholder Workshop, Kansas City, MO, April 15-17, 2008. ARS/USDA Lead SY recorded and organized the “Percid” and “Physiology” break-out sessions. SCA participants were also in attendance.
Early Life Stage Culture Workshop held in conjunction with the USDA/North Central Regional Aquaculture Center, November 3, 2007, in southwestern Wisconsin. Used a variety of species as examples.
20th Annual Native American Fish and Wildlife Society Conference, Great Lakes Region “Northern Wisconsin Aquaculture Demonstration Facility Overview”. Presented by Northern Aquaculture Demonstration Facility (NADF) Manager, Lac du Flambeau, WI, September 13, 2007. Wisconsin Aquaculture Industry Advisory Committee and the Wisconsin Aquaculture Association Meeting, “Rearing Advanced Growth Walleye in Northern Wisconsin”. Presented by NADF Manager, Bayfield, WI, September 7, 2007.
“Viral Hemorrhagic Septicemia Virus Symposium”. Organized by NADF and the Wisconsin Veterinary Diagnostic Laboratory, Madison, WI, August 9, 2007.
Workshop on the “Introduction to Aquaculture” and Advanced Aquaculture” presented at the Wisconsin Association of Agricultural Educators (WAAE) Summer Conference on June 25-28, 2007, Madison, Wisconsin. Presented by Great Lakes Water Institute SCA cooperators.
NADF Field Day and VHS Biosecurity Workshop on “How to Protect Your Farm from VHS and Other Diseases”. Organized by the Northern Aquaculture Demonstration Facility, Bayfield, WI, June 14, 2007.
Gahr, S.A., Vallejo, R.L., Weber, G.M., Shepherd, B.S., Silverstein, J., Rexroad III, C.E. 2008. Effects of short term growth hormone treatment on the rainbow trout (Oncorhynchus mykiss) liver and muscle transcriptomes. Physiological Genomics. 32:380-9.