Browsing by Subject "red drum"
Now showing 1 - 10 of 10
Results Per Page
Sort Options
Item Biological Activity of Thyrotropin in Two Teleost Fish, Red Drum (Sciaenops ocellatus) and Goldfish (Carassius auratus)(2012-07-16) Miller, Thomas CharlesThyrotropin (TSH) is a glycoprotein hormone released from the pituitary gland to promote the synthesis and secretion of thyroid hormone. The existence of well-established peripheral mechanisms for regulation of thyroid hormone delivery to targets has called into question the significance of TSH as a primary regulator of circulating thyroid hormone concentrations in fish. However, relatively little is known about the regulation or action of endogenously secreted teleost TSH, largely due to lack of purified TSH suitable for biological testing and immunoassay development. I developed a red drum in vivo bioassay to aid in the production and purification of recombinant TSH from the red drum, a perciform fish demonstrating dynamic daily thyroxine (T4) cycles hypothesized to be driven by TSH. Exogenous bovine TSH injection resulted in a time and dose-dependent increase in circulating TSH and T4 in red drum. However, the sensitivity of the red drum thyroid gland to stimulation by bovine TSH was lost during growth under controlled laboratory conditions, even when circulating levels of exogenously-administered mammalian TSH remained elevated. The insensitivity of the thyroid was not due to prior TSH injection or feed source. Because insensitivity of the Thyrotropin (TSH) is a glycoprotein hormone released from the pituitary gland to promote the synthesis and secretion of thyroid hormone. The existence of well-established peripheral mechanisms for regulation of thyroid hormone delivery to targets has called into question the significance of TSH as a primary regulator of circulating thyroid hormone concentrations in fish. However, relatively little is known about the regulation or action of endogenously secreted teleost TSH, largely due to lack of purified TSH suitable for biological testing and immunoassay development. I developed a red drum in vivo bioassay to aid in the production and purification of recombinant TSH from the red drum, a perciform fish demonstrating dynamic daily thyroxine (T4) cycles hypothesized to be driven by TSH. Exogenous bovine TSH injection resulted in a time and dose-dependent increase in circulating TSH and T4 in red drum. However, the sensitivity of the red drum thyroid gland to stimulation by bovine TSH was lost during growth under controlled laboratory conditions, even when circulating levels of exogenously-administered mammalian TSH remained elevated. The insensitivity of the thyroid was not due to prior TSH injection or feed source. Because insensitivity of the red drum thyroid precluded their use as a bioassay species, the plasma TSH and T4 response to exogenous TSH was next characterized in goldfish. The T4 response in goldfish was stable and repeatable, with T4 levels peaking at 5 hours and remaining elevated for more than 11 hours after bovine TSH injection. Plasma TSH peaked from 2-5 hours following TSH injection with more than 90 percent cleared by 11 hours. The goldfish bioassay was further utilized to evaluate the effects of structural modifications on TSH biological activity. Substitution of four positively charged amino acids at the n-recombinant human TSH, had the same effect in goldfish. The heterothyrotropic potency of mammalian follicle stimulating hormone in goldfish was also enhanced by the same amino acid substitutions. Finally, the importance of oligosaccharides to TSH bioactivity was also examined in goldfish. Deglycosylation abolished TSH bioactivity, even when immunoreactivity persisted in circulation. Furthermore, recombinant canine TSH was less potent when produced in cell lines generating insect-type glycosylation than when produced in a cell line capable of mammalian-type glycosylation. These studies utilizing recombinant mammalian demonstrated conservation of mammalian TSH hormone-receptor interactions in goldfish, suggesting TSH function might likewise be conserved. Thus, I have established goldfish as a sensitive and stable bioassay which can now be utilized to monitor the biological activity of teleost TSH expressed in vitro as well as to evaluate how structural modifications of the TSH molecule influence its vivo biological activity.Item Contrasting survival strategies of hatchery and wild red drum: implications for stock enhancement(2009-05-15) Beck, Jessica LouisePost-release survival of hatchery fishes is imperative to the success of any supplemental stocking program. The purpose of this research was to identify differences between hatchery and wild red drum (Sciaenops ocellatus) and determine if pre-release exposure techniques improve survival of hatchery individuals. Objectives were to contrast survival skills of hatchery and wild red drum from different locations, and examine if exposure to natural stimuli (e.g., habitat, predators, live prey) enhances survival skills in na?ve hatchery red drum. Laboratory trials using high-speed videography (250 frames per second, fps) and field mesocosm experiments were used to investigate differences in prey-capture (e.g., attack distance, mean attack velocity, capture time, maximum gape, time to maximum gape, gape cycle duration, and foraging behaviors) and anti-predator performance (e.g., reaction distance, response distance, maximum velocity, time to maximum velocity, mean acceleration, and maximum acceleration) of hatchery and wild red drum. Results indicated that anti-predator performance measures differed significantly between hatchery and wild red drum. Variability in prey-capture and anti-predator performance for hatchery and wild red drum was high (CV range: 5.6 ? 76.5%), and was greatest for hatchery fish for the majority of performance variables tested. Exposure to habitat (Spartina alterniflora marsh) did not appear to afford any obvious survival benefits to hatchery red drum, although survival skills did vary according to ontogenetic stage. Hatchery red drum exposed to natural predators (pinfish, Lagodon rhomboides) exhibited significantly greater attack distances during feeding events, and anti-predator performance variables were 20 ? 300% in these individuals versus na?ve red drum. In predation experiments with free-ranging pinfish predators, mortality rates (Z) ranged from 0.047 ? 0.060 h-1 ? predator-1; however no significant differences in mortality were found between fish reared with and without predators. Hatchery red drum reared on live prey (Artemia franciscana, mysid shrimp) demonstrated enhanced prey-capture and foraging behaviors as well as anti-predator performance relative to fish reared on artificial (pellet) diets. Findings of this research indicate that several behavioral patterns differed between hatchery and wild red drum; however, these differences can be mediated through the use of various pre-release exposure techniques.Item Evaluation of fisheries by-catch and by-product meals in diets for red drum (Sciaenops ocellatus)(Texas A&M University, 2006-04-12) Whiteman, KaseyBy-catch and wastes from processed fish and shrimp constitute a sizeable portion of commercial fishery landings. This discarded material is potentially valuable, for its content of fish meals and other substances. Fish meals, in particular, are increasingly in short supply for the manufacture of animal feeds, including feeds for farmed fish. Therefore, in this study, various by-catch and by-product meals of marine origin were evaluated with red drum (Sciaenops ocellatus), a carnivorous fish species native to the Gulf of Mexico that has been cultured over the past two decades for stock enhancement as well as for food. Four different kinds of by-catch or by-product meals [shrimp by-catch meal, shrimp processing waste meal, red salmon (Oncorhynchus nerka) head meal, and Pacific whiting (Merluccius productus) meal] were substituted for Special Select?? menhaden fish meal at two different levels (33% or 67% of crude protein) in prepared diets for red drum. Another treatment consisted of shrimp processing waste meal formulated on a digestible-protein basis to replace 33% of the protein from menhaden fish meal. Levels of calcium carbonate were reduced in two additional diets containing Pacific whiting, to evaluate the effects of ash content. Diets were formulated to contain 40% crude protein, 12% lipid, and 3.5 kcal digestible energy/g. Each diet was fed to triplicate groups of juvenile red drum in 38-l aquaria containing brackish water (7 ?? 1 ppt) in two separate 6-week feeding trials. Survival, weight gain, feed efficiency, protein efficiency ratio and body composition responses were measured in each trial. Fish fed the by-catch meal at either level of substitution performed as well as fish fed the control diet containing protein solely from menhaden fish meal; whereas, fish fed the shrimp processing waste meal diets did significantly (P ≤ 0.05) worse than the controls, even when fed a diet formulated to be equivalent on a digestible-protein basis. Fish fed the red salmon head meal diet fared poorly, probably owing to an excessive amount of lipid in the diet that tended to become rancid. Overall, by-catch meal associated with shrimp trawling appears to be a very suitable protein feedstuff for red drum.Item Evaluation of Seafood Processing Wastes in Prepared Feeds for Red Drum (Sciaenops ocellatus)(2012-07-16) Pernu, Benjamin MarkHigh feed costs and increasing demand for fishmeal have intensified the search for alternative protein sources which are needed to allow world aquaculture to continue expanding. A severely underused marine resource is processing wastes of various types of seafood, which are often disposed of at great cost. Therefore, this study was conducted to evaluate three different types of seafood processing wastes as potential feed ingredients for the red drum (Sciaenops ocellatus). The three processing wastes evaluated were heads and shells from Penaeid shrimp, and viscera and skeletal remains from filleted black drum (Pogonias cromis) and channel catfish (Ictaluras punctatus). These wastes were blended with soybean meal in a 40:60 ratio, dry extruded and dried to produce stable ingredients. All three byproduct meals produced had crude protein levels ranging from 45 to 50 percent. Two feeding trials were conducted to evaluate the different processing waste byproduct meals in comparison to menhaden fishmeal. A digestibility trial was conducted with sub-adult red drum which led to the computation of apparent digestibility coefficients (ADCs) for organic matter, protein, lipid and energy for each of the byproduct meals. Each byproduct meal had relatively high ADC values that were generally similar to those of menhaden fishmeal. A comparative growth trial with red drum was then conducted in which experimental diets were formulated with the three byproduct meals replacing menhaden fishmeal on an equal-digestible-protein basis at levels of 65 percent, 80 percent, or 95 percent. Juvenile red drum were fed the various diets for 8 weeks in a brackish (6 plus/minus 1 ppt) water recirculating system after which weight gain, survival, feed efficiency, as well as whole-body proximate composition and condition indices were measured. All three of the byproduct meals could replace up to 65 percent of the protein provided by fishmeal without adversely affecting performance of red drum. However, the shrimp byproduct consistently provided the highest performance values at 80 percent replacement. The catfish byproduct yielded the lowest fish performance at all levels. This study indicates that dry extrusion of seafood processing wastes can be used to replace a considerable amount of fishmeal in feeds for red drum.Item Evaluation of Whole and Lipid-Extracted Algae Meals (LEA) in the Diet of Juvenile Red Drum (Sciaenops ocellatus) and Digestibility of LEA by Red Drum and Hybrid Striped Bass (Morone chrysops x Morone saxatilis)(2013-04-02) Patterson, Donovan AaronAs aquaculture continues to expand, protein sources have become more costly and less available. Simultaneously, lipid-extracted algal meals (LEA) (co-products of bio-diesel production) are becoming increasingly available as alternative sources of energy are investigated. By integrating LEA into aquaculture diets, feed prices could be lowered and bio-diesel production would have an additional revenue stream. Three feeding trials each of 7 weeks duration were conducted to evaluate five different algal meals as partial replacements for fishmeal and soy protein concentrate in diets for juvenile red drum (Sciaenops ocellatus). Apparent digestibility coefficients (ADCs) for CP and energy in various LEAs also were determined with red drum and hybrid striped bass (HSB). In the first trial, whole algae meal and LEA derived from Navicula sp. replaced 5 or 10% of the crude protein (CP) in the reference diet. Weight gain, feed efficiency (FE), hepatosomatic index (HSI), as well as protein and energy retention were not significantly (P>0.05) affected by the dietary treatments. Algal inclusion significantly affected the ADCs of the various dietary treatments for dry matter, CP, and energy. The inclusion of ash in the form of diatomaceous earth improved digestibility of protein as well as weight gain, survival and FE. A second feeding trial evaluated LEA derived from Chlorella sp. processed at high temperatures, replacing 5, 10, 20, and 25% of the CP in the reference diet. Weight gain, FE, survival, and protein efficiency ratio (PER) were significantly reduced at substitution levels of 20 and 25%. The third feeding trial evaluated LEA derived from Nanochloropsis salina, replacing 5, 7.5, 10, and 15% of the CP in the reference diet. Weight gain, FE, survival, and PER were significantly affected by some dietary treatments, with the 15% substitution levels causing significant reductions in performance. Intraperitoneal fat ratio and whole-body lipids were significantly lower in the fish fed the 15% substitution diet. Based on the results of these experiments, replacement of up to 10% of CP from fishmeal and soy protein concentrate with LEA was possible without causing substantial reductions in fish performance, and the whole algae product provided a more nutritious product. Red drum and HSB showed similar responses in their ability to digest CP and energy from the various algal products, although ADCs varied greatly among the different products and processing methods.Item Genetic studies for aquaculture and stock-enhancement of red drum (Sciaenops ocellatus)(Texas A&M University, 2007-09-17) Ma, LiangHypervariable, nuclear-encoded microsatellites were used to (i) estimate genetic effective size (Ne) of red drum spawning over a two-week period in nine brood tanks at a TPWD hatchery; (ii) estimate heritability of early-larval growth and of growth rate and cold tolerance of juveniles; and (iii) test Mendelian segregation and independent assortment of 31 nuclear-encoded microsatellites. Assuming all tanks contributed equally to an offspring population, the maximum (expected) and observed Ne over the nine brood tanks was 43.2 and 27.0, respectively. The estimate of Ne based on observed variation in family size was 19.4. Simulations indicated that over a limited time period the simplest approach to maximizing Ne for a release population would be to utilize equal numbers of progeny from each brood tank. A family (genetic) effect was found to contribute significantly to the variance in early larval growth, juvenile growth rate, and cold tolerance. Estimates of narrow-sense heritability for these three traits were 0.07 +- 0.03, 0.52 +- 0.21 and 0.20 +- 0.10 (two growth intervals measured), and 0.30 +- 0.11, respectively, under the genetic models employed. The relatively low estimate of heritability for early larval growth suggests that genetic improvement for this trait likely would be slow. The heritability estimates for juvenile growth rate and cold tolerance, alternatively, suggest that genetic selection for these traits could be effective. Segregation at all 31 microsatellites fit Mendelian expectations for autosomal loci; a null allele was inferred at two of the microsatellites. Results from pairwise tests of independent assortment demonstrated that 20 of the 31 microsatellites could be placed into seven linkage groups. Additional linkage groups inferred from a prior study increased the number of inferred linkage groups in red drum to nine, with a range of two - five (avg. = 2.78) microsatellites in each linkage group. The remaining 11 microsatellites tested in this study assorted independently from all other microsatellites, suggesting the possibility of 11 additional linkage groups.Item Interaction of temperature, dissolved oxygen and feed energy on ecophysiological performance of juvenile red drum(Texas A&M University, 2008-10-10) Fontaine, Lance PierreThe red drum (Sciaenops ocellatus) is important for recreational fishing and aquacultural production in Texas' coastal waters and elsewhere in the nearshore Gulf of Mexico and in subtemperate to subtropical areas of the western North Atlantic Ocean. I performed indoor-tank and outdoor-pond experiments, in conjunction with automa ted respirometry and ecophysiological modeling, to assess interacting effects of temperature, dissolved-oxygen concentration (DO) and feed energy density on survival, growth, metabolism, and other measures of juvenile red drum performance. The main objective was to test an energy/metabolism tradeoff hypothesis, which states that growth of fish exposed to high temperatures can be limited by available feed energy; whereas, growth of fish exposed to lower temperatures can be limited by their metabolic capacity to exploit available feed energy. Also, I examined the influence of DO on this relationship and evaluated the effects of cyclical regimes of temperature and DO on fish performance. Insights from laboratory-based feeding trials were incorporated in experiments conducted in hatchery ponds to assess effects of oxygen supplementation and dietary additives - nucleotides and prebiotics - on performance in a more natural setting. In examining these issues, various technologies were developed. These included a computer-based apparatus for autonomously inducing cyclical regimes of temperature and DO in experimental tanks over an extended period of time. Additionally, I developed a soft feed with low energy-density to simulate natural forage. Experimental results supported the principal research hypothesis: At high temperature and DO, ecophysiological performance of juvenile red drum was enhanced by feeding to satiation with a high-energy feed (15.9 kJ/g) versus with a foragesimulating feed having lower energy density (4.1 kJ/g). Cyclical regimes of temperature and DO - as imposed in my particular laboratory experiments -did not impart growth benefits; however, the potential for enhanced growth via an appropriate cyclical environmental regime remains intact. Results from outdoor-pond experiments were consistent with laboratory results; however, the strong positive effect of feed energy density overwhelmed potential effects of dietary additives or oxygen supplementation on growth.Item Regulation of Thyrotropin mRNA Expression in Red Drum, Sciaenops ocellatus(2012-10-19) Jones, Richard AlanThe role of thyroid-stimulating hormone (TSH) in the regulation of peripheral thyroid function in non-mammalian species is still poorly understood. Thyroxine (T?), the principal hormone released from the thyroid gland in response to TSH stimulation, circulates with a robust daily rhythm in the sciaenid fish, red drum. Previous research has suggested that the red drum T? cycle is circadian in nature, driven by TSH secretion in the early photophase and inhibited by T? feedback in the early scotophase. To determine whether TSH is produced in a pattern consistent with driving this T? cycle, I developed quantitative real time RT-PCR (qPCR) techniques to quantify the daily cycle of expression of the pituitary TSH subunits GSU[alpha], and TSH[beta]. I found that pituitary TSH expression cycled inversely to, and 6-12 hours out of phase with, the T? cycle, consistent with the hypothesis that TSH secretion drives the T? cycle. To examine the potential role of deiodinases in negative feedback regulation of this TSH cycle, I also utilized qPCR to assess the pituitary expression patterns of the TH activating enzyme outer-ring deiodinase (Dio2) and the TH deactivating enzyme inner ring deiodinase (Dio3). Whereas Dio2 was not expressed with an obvious daily cycle, Dio3 was expressed in the pituitary mirroring the TSH cycle. These results are consistent with T? negative feedback on TSH and suggest that TH inactivation by pituitary cells is an important component of the negative feedback system. To further examine the TH regulation of this Dio3 cycle, I developed an immersion technique to administer physiological doses of T? and T? in vivo. Both hormones persist in static tank water for at least 40 hours. Immersion in 200ng/ml T? significantly increased both plasma T? and T? within physiological ranges above control at 4.5 hours. Immersion in 100ng/ml T? increased plasma T? within physiological ranges over control by 22 hours while significantly decreasing plasma T? below control, presumably through inhibition of TSH secretion. T? also significantly inhibited the expression of the TSH [alpha] and [beta] subunits at 4.5 and 22 hours of immersion whereas T? immersion significantly inhibited the expression of the [alpha] and [beta] subunits of TSH by 22 hours. Both Dio2 and Dio3 expression were significantly diminished by T3 and T? at 22 hours. Inhibition of circulating THs with the goitrogen methimazole significantly increased the expression of TSH. These results indicate that both T? and T? are capable of negative feedback regulation of TSH expression in red drum on a time scale consistent with the T? daily cycle, and further support Dio3 destruction of THs in the pituitary, potentially regulated by circulating T?, as a critical component of negative feedback on TSH. This study supports the importance of central mechanisms acting through pituitary TSH secretion in regulating thyroid function in red drum.Item Supplementation of Organic Acids and Algae Extracts in Aqua Feeds: Immunological Impacts(2013-12-02) Mendoza Rodriguez, Maria GTwo organic acids, polyhydroxybutyrate (PHB) and potassium diformate (KDF) have been researched to only a limited extent with aquatic species but have been shown to have various positive effects on terrestrial animals. Two algae extracts, carrageenan and alginic acid, also have been shown to elicit immunostimulation in some fish. Therefore, the present study was conducted with red drum (Sciaenops ocellatus) as a model marine species to study the effects of organic acids and algae extracts as feed supplements by evaluating several humoral immune responses. Two feeding trials, one of 7-week duration and the other of 3-week were conducted with disease-free juvenile red drum (average initial wt. 2.6?0.2 g and 78.2 ?0.2 g, respectively). Semipurified diets were formulated to be isocaloric and contain 40% crude protein. Experimental diets were produced by supplementing the basal diet with KDF at 0.6%, PHB at 2%, alginic acid at 1% or carrageenan at 0.5% by weight in place of cellulose. Fish were stocked into 110-L aquaria operated as a recirculating system with each diet assigned to three replicate aquaria containing either 15 fish (7-week trial) or 9 fish per aquarium (3-week trial). All fish were fed their respective diets at the same fixed percentage of body weight (initially 6% and gradually reduced to 4% as the fish grew). Body weight was monitored by collectively weighing fish from each aquarium every week. At the end of each feeding trial, weight gain and feed efficiency were significantly (P<0.0001) reduced in fish feed PHB compared to the basal diet and both algae extracts. There were no significant differences in condition indices such as hepatosomatic index (HSI) and intraperitoneal fat (IPF) ratio among fish fed the various diets. Lysozyme activity was significantly higher in fish fed alginic acid. The greatest phagocytic activity was found in fish fed the diet containing PHB. Total immunoglobulin level was higher in fish fed the diet supplemented with carrageenan. Goblet cell proliferation was greatest in the posterior end of the gastrointestinal tract but not different among dietary treatments. Organic acids and algae extracts evaluated in this study produced variable immunological responses in red drum with carrageenan showing the greatest potential as an immunostimulant.