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Markus Hecker - One of the best experts on this subject based on the ideXlab platform.
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Toxicokinetic Models for Bioconcentration of Organic Contaminants in Two Life Stages of White Sturgeon (Acipenser transmontanus)
'American Chemical Society (ACS)', 2021Co-Authors: Chelsea Grimard, John P Giesy, Markus Hecker, Annika Mangold-döring, Hattan Alharbi, Lynn Weber, Natacha Hogan, Paul D. Jones, Markus BrinkmannAbstract:The White Sturgeon (Acipenser transmontanus) is an endangered ancient fish species that is known to be particularly sensitive to certain environmental contaminants, partly because of the uptake and subsequent toxicity of lipophilic pollutants prone to bioconcentration as a result of their high lipid content. To better understand the bioconcentration of organic contaminants in this species, toxicokinetic (TK) models were developed for the embryo-larval and subadult life stages. The embryo-larval model was designed as a one-compartment model and validated using whole-body measurements of benzo[a]pyrene (B[a]P) metabolites from a waterborne exposure to B[a]P. A physiologically based TK (PBTK) model was used for the subadult model. The predictive power of the subadult model was validated with an experimental data set of four chemicals. Results showed that the TK models could accurately predict the bioconcentration of organic contaminants for both life stages of White Sturgeon within 1 order of magnitude of measured values. These models provide a tool to better understand the impact of environmental contaminants on the health and the survival of endangered White Sturgeon populations
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Investigating the Role of Ionoregulatory Processes in the Species- and Life-Stage-Specific Differences in Sensitivity of Rainbow Trout and White Sturgeon to Cadmium
2018Co-Authors: Kamran Shekh, Markus Hecker, Song Tang, Som NiyogiAbstract:There are huge variations in life-stage- and species-specific sensitivities among the fishes to the exposure with metals; however, the physiological mechanisms underlying these differences are not well understood to date. This study revealed significant life-stage-specific (larval, swim-up, and juvenile) and species-specific differences between two evolutionary distant species of fishes, rainbow trout (Oncorhynchus mykiss) and White Sturgeon (Acipenser transmontanus), following acute exposures to Cd. Although the 96 h LC50 of Cd was similar in both species at the larval stage, trout demonstrated an increased sensitivity to Cd at later life stages as compared to Sturgeon. Moreover, exposure to Cd disrupted calcium (Ca) uptake and whole body Ca levels in trout by a greater degree relative to that in Sturgeon regardless of life stage. Finally, White Sturgeon demonstrated a lower affinity for Cd uptake relative to the more sensitive rainbow trout. This infers a differential nature of the interaction between Cd and Ca transport pathways in the two species and partially explains the differences in Cd sensitivity between rainbow trout and White Sturgeon described previously. Overall, our results suggest that species- and life-stage-specific differences in sensitivity to waterborne Cd in fish are likely a function of the interplay between Cd uptake and Cd-induced disruption of Ca homeostasis
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Linking Oxidative Stress and Magnitude of Compensatory Responses with Life-Stage Specific Differences in Sensitivity of White Sturgeon (Acipenser transmontanus) to Copper or Cadmium
2016Co-Authors: Song Tang, Jon A Doering, John P Giesy, Kamran Shekh, Jianxian Sun, Shawn C. Beitel, Sarah Patterson, Sarah Crawford, Steve B. Wiseman, Markus HeckerAbstract:Sensitivity of White Sturgeon (Acipenser transmontanus) to copper (Cu) or cadmium (Cd) has been shown to significantly differ as a function of life-stage. This study investigated oxidative stress, metal homeostasis, and associated compensatory responses as potential mechanisms of this sensitivity pattern in three early life-stages. Sturgeon were most sensitive to Cu at 15 days post hatch (dph), which was accompanied by a significant increase in lipid peroxidation (LPO). Genes involved with amelioration of oxidative stress were significantly less inducible at this stage than in older, less sensitive fry. At 48 dph, acute lethality of Sturgeon exposed to Cd was greatest and body LPO was significantly induced by 3.5-fold at 5 μg Cd/L. Moreover, there was a small but significant increase in antioxidative responses. At 139 dph, Sturgeon were most tolerant to Cu and Cd and accumulation of these metals was least. Also, expression of metallothionein (MT) and apoptotic genes were greatest while expression of metal transporters was reduced and concentration of LPO was not different from controls. Our results suggest that life-stage specific sensitivity of White Sturgeon to metals is complex, encompassing differences in the ability to mount compensatory responses important for metal homeostasis and combating oxidative stress and concomitant damages
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High Conservation in Transcriptomic and Proteomic Response of White Sturgeon to Equipotent Concentrations of 2,3,7,8-TCDD, PCB 77, and Benzo[a]pyrene
2016Co-Authors: Jon A Doering, Steve Wiseman, John P Giesy, Song Tang, Jianxian Sun, Hui Peng, Bryanna K. Eisner, Markus HeckerAbstract:Adverse effects associated with exposure to dioxin-like compounds (DLCs) are mediated primarily through activation of the aryl hydrocarbon receptor (AHR). However, little is known about the cascades of events that link activation of the AHR to apical adverse effects. Therefore, this study used high-throughput, next-generation molecular tools to investigate similarities and differences in whole transcriptome and whole proteome responses to equipotent concentrations of three agonists of the AHR, 2,3,7,8-TCDD, PCB 77, and benzo[a]pyrene, in livers of a nonmodel fish, the White Sturgeon (Acipenser transmontanus). A total of 926 and 658 unique transcripts were up- and down-regulated, respectively, by one or more of the three chemicals. Of the transcripts shared by responses to all three chemicals, 85% of up-regulated transcripts and 75% of down-regulated transcripts had the same magnitude of response. A total of 290 and 110 unique proteins were up- and down-regulated, respectively, by one or more of the three chemicals. Of the proteins shared by responses to all three chemicals, 70% of up-regulated proteins and 48% of down-regulated proteins had the same magnitude of response. Among treatments there was 68% similarity between the global transcriptome and global proteome. Pathway analysis revealed that perturbed physiological processes were indistinguishable between equipotent concentrations of the three chemicals. The results of this study contribute toward more completely describing adverse outcome pathways associated with activation of the AHR
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Differences in Activation of Aryl Hydrocarbon Receptors of White Sturgeon Relative to Lake Sturgeon Are Predicted by Identities of Key Amino Acids in the Ligand Binding Domain
2015Co-Authors: Jon A Doering, Reza Farmahin, Steve Wiseman, Sean W Kennedy, John P Giesy, Shawn C. Beitel, Markus HeckerAbstract:Dioxin-like compounds (DLCs) are pollutants of global environmental concern. DLCs elicit their adverse outcomes through activation of the aryl hydrocarbon receptor (AhR). However, there is limited understanding of the mechanisms that result in differences in sensitivity to DLCs among different species of fishes. Understanding these mechanisms is critical for protection of the diversity of fishes exposed to DLCs, including endangered species. This study investigated specific mechanisms that drive responses of two endangered fishes, White Sturgeon (Acipenser transmontanus) and lake Sturgeon (Acipenser fulvescens) to DLCs. It determined whether differences in sensitivity to activation of AhRs (AhR1 and AhR2) can be predicted based on identities of key amino acids in the ligand binding domain (LBD). White Sturgeon were 3- to 30-fold more sensitive than lake Sturgeon to exposure to 5 different DLCs based on activation of AhR2. There were no differences in sensitivity between White Sturgeon and lake Sturgeon based on activation of AhR1. Adverse outcomes as a result of exposure to DLCs have been shown to be mediated through activation of AhR2, but not AhR1, in all fishes studied to date. This indicates that White Sturgeon are likely to have greater sensitivity in vivo relative to lake Sturgeon. Homology modeling and in silico mutagenesis suggests that differences in sensitivity to activation of AhR2 result from differences in key amino acids at position 388 in the LBD of AhR2 of White Sturgeon (Ala-388) and lake Sturgeon (Thr-388). This indicates that identities of key amino acids in the LBD of AhR2 could be predictive of both in vitro activation by DLCs and in vivo sensitivity to DLCs in these, and potentially other, fishes
Silas S O Hung - One of the best experts on this subject based on the ideXlab platform.
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Development of growth rate, body lipid, moisture, and energy models for White Sturgeon (Acipenser transmontanus) fed at various feeding rates.
eScholarship University of California, 2017Co-Authors: Lee Seunghyung, Silas S O Hung, Sonmez Ozan, Fadel, James GAbstract:The objectives were to develop and evaluate: 1) growth rate models, 2) body lipid, moisture, and energy models for White Sturgeon fed at various feeding rates (FR; % body weight [BW] per day) and then evaluate responses at proportions of optimum feeding rate (OFR) across increasing BW (g). For objective 1, 19 datasets from the literature containing initial BW, FR and specific growth rate (SGR; % BW increase per day) were used. For objective 2, 12 datasets from the literature (11 from objective 1) containing SGR, FR, final BW, body lipid (%), protein (%), ash (%), moisture (%), and energy (kJ/g) were used. The average rearing temperatures was 19.2 ± 1.5 °C (mean ± SD). The average nutrient compositions and gross energy of the diets were 45.7 ± 4.3% protein, 14.8 ± 3.2% lipid, and 20.4 ± 1.3 kJ/g, respectively. The logistic model was used for objectives 1 and 2 to develop a statistical relationship between SGR and FR, then an iterative technique was used to estimate OFR for each dataset. For objective 2, the statistical relationship between body lipid, energy, and moisture and FR was established. Using the OFR estimate, SGR, body lipid, energy and moisture were computed at various FR as a proportion of OFR. Finally, a nonparametric fitting procedure was used to establish relationships between SGR, body lipid, energy and moisture (responses) compared with BW (predictor) at various proportions of OFR. This allows visualization of the effect of under- or over-feeding on the various responses. When examining the differences between OFR at 100% and various proportions of OFR, SGR differences decrease and moisture differences increase as BW increases. Lipid and energy differences decrease as BW increases. To our knowledge, these are the first description of changes in nutrient compositions when White Sturgeon are fed at various FR. Because physiological and behavioral properties that are unique to Sturgeon, results from this study are specific to Sturgeon under the conditions of this study and cannot be compared directly with salmonids even if some of the results are similar. This research provides insight to designing future nutritional studies in Sturgeon
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effects of feed restriction on the upper temperature tolerance and heat shock response in juvenile green and White Sturgeon
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2016Co-Authors: Seunghyung Lee, Silas S O Hung, Liran Y Haller, Nann A Fangue, Christine E Verhille, Juan Zhao, Anne E TodghamAbstract:The objective of the current study was to investigate the effects of feed restriction on whole-organism upper thermal tolerance and the heat shock response of green and White Sturgeon to determine how changes in food amount might influence physiological performance of each species when faced with temperature stress. Two parallel feed restriction trials were carried out for juvenile green (202g; 222-day post hatch: dph) and White Sturgeon (205g; 197-dph) to manipulate nutritional status at 12.5%, 25%, 50%, or 100% of optimum feeding rate (100% OFR were 1.6% and 1.8% body weight/day, respectively) for four weeks. Following the trials, the critical thermal maximum (CTMax, 0.3°C/min) of Sturgeon (N=12/treatment/species) was assessed as an indicator of whole-organism upper thermal tolerance. To assess temperature sensitivity, Sturgeon (N=9/treatment/species) were acutely transferred to two temperature treatments (28°C and 18°C as a handling control) for 2h followed by 2h of recovery at 18°C before being sacrificed, and gill, brain, and mucus sampled for measurements of 70-kDa heat shock protein levels (Hsc/Hsp70). Feeding rate had species-specific effects on CTMax in green and White Sturgeon such that CTMax of green Sturgeon decreased as the magnitude of feed restriction increased; whereas, CTMax of White Sturgeon did not change with feed restriction. Elevated temperature (28°C) and feed restriction increased Hsc/Hsp70 levels in the gill tissue of green Sturgeon, while heat shock increased Hsc/Hsp70 levels in the mucus of White Sturgeon. Our results suggest that green Sturgeon may be more susceptible to temperature stress under food-limited conditions.
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effects of feeding rate on growth performance and nutrient partitioning of young of the year White Sturgeon acipenser transmontanus
Aquaculture Nutrition, 2016Co-Authors: Seunghyung Lee, Liran Y Haller, Nann A Fangue, J G Fadel, Silas S O HungAbstract:A 10-week growth trial was performed to evaluate the effects of feeding rate on growth performance, nutrient partitioning, and to determine the optimum feeding rate for young-of-the-year White Sturgeon. Three tanks with 30 fish per tank each were assigned to five feeding rates, 0.4–2.0% body weight per day (BW day−1). Weight gain significantly (P < 0.05) increased with increasing feeding rate up to 1.2% BW day−1. Feed efficiency exhibited an inverse relationship to weight gain. Hepatosomatic and gonadal-fat-body (GFB)-somatic indices were significantly affected by feeding rate, and the lowest values were observed at 0.4% BW day−1. The increased feeding rate significantly affected whole-body and carcass lipid and moisture contents. Protein gain in the carcass, but not in the GFB, was significantly influenced by feeding rate. Lipid gain in the carcass and GFB was also significantly affected by feeding rate. Four regression models were tested for the estimation of optimum feeding rate, including one-slope straight broken-line, two-slope straight broken-line, quadratic broken-line and quadratic models. Adjusted coefficient of correlation and corrected Akaike information criterion were used to compare model performance. The quadratic broken-line model was chosen as the best based on the criteria. The estimated optimum feeding rate for young-of-the-year White Sturgeon (360 g) is 1.5% BW day−1.
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Responses of heat shock protein 70 and caspase-3/7 to dietary selenomethionine in juvenile White Sturgeon.
eScholarship University of California, 2016Co-Authors: Wang Weifang, Silas S O Hung, Lee Seunghyung, Deng Dong-fangAbstract:An 8-week feeding trial was conducted to investigate the responses of juvenile White Sturgeon (Acipenser transmontanus) to elevated dietary selenium (Se) based on the determination of the RNA/DNA ratio in muscle, heat shock protein 70 (Hsp70), and caspase-3/7 in muscle and/or liver tissues. Four semi-purified test diets were prepared by adding different levels of L-selenomethionine (0, 50, 100, and 200 mg/kg diet). The analytical determinations of total Se were 2.2, 19.7, 40.1, and 77.7 mg/kg diet. The Sturgeon (initial body weight: 30 ± 2 g; mean ± SEM) were raised in indoor tanks provided with flow through freshwater (18-19 °C). There were three replicates for each dietary treatment with 25 fish per replicate. The liver and muscle tissues were collected at 4 and 8 weeks after feeding the test diets. A significant interaction between duration and levels of dietary Se exposures on RNA/DNA ratio in the muscle tissue was detected (P < 0.05). Although there was no significant main effect due to the duration of dietary Se exposures (i.e., 4 weeks versus 8 weeks) on muscle RNA/DNA ratio (P ≥ 0.05), the ratio was significantly decreased with increasing dietary Se levels. Significant main effects were caused by the duration and levels of dietary Se exposures on Hsp70 in both the muscle and liver tissues, with significant increases in Hsp70 due to a longer exposure (8 weeks) and higher levels (40.1 and 77.7 mg Se/kg diet) of dietary Se. The caspase-3/7 activity in the liver were significantly higher in fish fed the diets containing 40.1 and 77.7 mg Se/kg diet than those fed the other diets. The toxic thresholds of Se in the muscle were estimated to be 32.2 and 26.6 mg Se/kg for the depressed specific growth rate and the induced Hsp70 response in muscle, respectively. This result indicated that the Hsp70 response in muscle is a more sensitive biomarker than the SGR of Sturgeon for evaluating Se toxicity in White Sturgeon. Results of the current study suggest that a mechanism involved with the activation of stress protein production and apoptosis protects White Sturgeon from the lethal effect of Se
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Responses of heat shock protein 70 and caspase-3/7 to dietary selenomethionine in juvenile White Sturgeon
KeAi, 2016Co-Authors: Weifang Wang, Silas S O Hung, Seunghyung Lee, Dongfang DengAbstract:An 8-week feeding trial was conducted to investigate the responses of juvenile White Sturgeon (Acipenser transmontanus) to elevated dietary selenium (Se) based on the determination of the RNA/DNA ratio in muscle, heat shock protein 70 (Hsp70), and caspase-3/7 in muscle and/or liver tissues. Four semi-purified test diets were prepared by adding different levels of L-selenomethionine (0, 50, 100, and 200 mg/kg diet). The analytical determinations of total Se were 2.2, 19.7, 40.1, and 77.7 mg/kg diet. The Sturgeon (initial body weight: 30 ± 2 g; mean ± SEM) were raised in indoor tanks provided with flow through freshwater (18–19 °C). There were three replicates for each dietary treatment with 25 fish per replicate. The liver and muscle tissues were collected at 4 and 8 weeks after feeding the test diets. A significant interaction between duration and levels of dietary Se exposures on RNA/DNA ratio in the muscle tissue was detected (P
Molly A H Webb - One of the best experts on this subject based on the ideXlab platform.
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effect of dietary fat on adipocyte size in farmed age 2 White Sturgeon acipenser transmontanus richardson 1836
Journal of Applied Ichthyology, 2018Co-Authors: H B Treanor, Serge I Doroshov, Isaac R Miller, Leif J Halvorson, J P Van Eenennaam, Molly A H WebbAbstract:Determining the age at which farmed Sturgeon begin storing ovarian fat will potentially enable Sturgeon farmers to adjust husbandry practices, such as feeding different dietary fat levels at an early age. We investigated the influence of dietary fat on the size of ovarian adipocytes in farmed age‐2 White Sturgeon Acipenser transmontanus. At age 1 month, all fish were fed a commercial high fat (HF; 17% fat) diet. At age 6 months, half were transitioned to an experimental low fat (LF; 9% fat) diet. Fish at this time averaged 160 g (±30 g), and individual tank density was 4.1 kg/m³. Tanks were 3.7 m in diameter, 1.3 m deep, each with a volume of 13.7 m³. Each tank maintained a flow rate of 150 L/min using groundwater with water temperatures ranging from 19 to 21°C and dissolved oxygen ranging from 6.5 to 12.0 ppm. All fish were fed the diet assigned to their tank for an additional 18 months prior to sampling. At age 25 months (now referred to as “age 2”), tissue was collected from fish and processed histologically. Adipocytes were measured along the ovarian fold (anterior), furthest from the ovarian fold (posterior), and randomly in between the anterior and posterior sections. Randomly chosen adipocytes from each location were measured histologically. Mean adipocyte size did not statistically differ among sample locations in fish fed the same diet. Once pooled by sampling location, average adipocyte size was 5,491.18 μm (±98.97) in fish fed the HF diet and 3,348.62 μm (±40.85) in fish fed the LF diet. Fish fed the HF diet had larger adipocytes than fish fed the LF diets (t = 20.01, df = 78.54, p < .01). The results demonstrate that diet can influence the size of adipocytes found in juvenile White Sturgeon ovaries. Additional research is needed to determine whether the accumulation of large adipocytes as a juvenile confers to adulthood and influences reproductive ability and caviar yield and quality.
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Potential Classification of Sex and Stage of Gonadal Maturity of Wild White Sturgeon
2016Co-Authors: Using Blood Plasma Indicators, Molly A H Webb, E P Foster, Carl B Schreck, W. Feist, Martin S FitzpatrickAbstract:Abstract.—Because White Sturgeon Acipenser transmontanus show no readily discernible external signs of gender, management agencies use surgical biopsies to determine the sex and stage of gonadal maturity of individuals. This procedure is highly invasive and can be difficult under field conditions. Therefore, gonadal tissue and blood were collected from White Sturgeon captured in tribal and commercial fisheries (fishery fish) and by fish and wildlife agencies (oversize fish) in the Columbia River basin to develop a method of determining sex and stage of maturity using the blood plasma indicators testosterone (T), 11-ketotestosterone (KT), estradiol (E2), and calcium (Ca21). The sex and stage of maturity was determined by histology or by visual examination in maturing fish. Plasma sex steroid levels were measured by radioimmunoassay, and plasma Ca21 was measured spectrophotometrically. White Sturgeon showed sex- and maturity-specific levels of steroids and Ca21. Stepwise discriminant function analysis (DFA) was used to choose the best variable(s) for predicting sex and stage of maturity, and quadratic DFA was conducted to classify fish into two groups of sex or four groups of sex and stage of maturity. In the classification of the fishery plus oversize fish, plasma T and E2 were the best predictors of sex and stage of maturity. Of the 151 females and 106 males, 85 % of the females and 79 % of the males were correctl
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ENVIRONMENTAL CONTAMINANTS IN White Sturgeon: IS ENDOCRINE DISRUPTION OCCURRING IN THE COLUMBIA RIVER?
2015Co-Authors: Grant W Feist, Molly A H Webb, E P Foster, Carl B Schreck, Martin S Fitzpatrick, Deke T. Gundersen, Alec G. MauleAbstract:The lower Columbia River supports one of the most productive White Sturgeon, Acipenser transmontanus, fisheries in North America. Fish trapped behind the dams of the hydroelectric system however, have reduced reproductive success when compared to animals in the free-flowing portion of the river. Reduced reproductive fitness of fish in these impounded sections of the river has been attributed to habitat, flow and temperature but environmental toxicants could also be playing a role. The long-lived, late-maturing and benthic lifestyle of Sturgeon make them particularly susceptible to the actions of persistent bioaccumulating pollutants. We are presenting the preliminary findings of an 60 ongoing study examining possible effects of environmental toxicants on Sturgeon reproductive physiology. Fish were collected from the free-flowing portion of the Columbia River in the estuary and pools above Bonneville, The Dalles and John Day dams. Condition factor (CF) and gonadosomatic index (GSI) were determined for each fish an
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investigating the use of plasma testosterone and estradiol 17β to detect ovarian follicular atresia in farmed White Sturgeon acipenser transmontanus
Aquaculture, 2011Co-Authors: Mariah J Talbott, Joel P Van Eenennaam, Javier Linarescasenave, Serge I Doroshov, Peter Struffenegger, Molly A H WebbAbstract:Abstract To improve quality and yield of caviar in farmed White Sturgeon it is essential to correctly assess the stage of ovarian maturity and avoid harvesting females with atretic ovarian follicles. To detect atresia by changes in blood plasma sex steroids, individual females (N = 10) in the late phase of oogenesis were repeatedly bled and their ovaries biopsied before and after onset of ovarian atresia. Follicular atresia was induced by transferring females from cold (10–13 °C) to warm water (20 °C). Ovarian follicle diameter increased and oocyte polarization index decreased in sampled fish over time. Plasma testosterone concentrations in fish with normal follicles were significantly higher, compared to fish with early histological signs of follicular atresia, such as structural changes in the chorion. Plasma estradiol concentrations declined to below detection limit prior to histological signs of atresia in 55% of the fish. Ninety five percent of fish with normal ovarian follicles and 93% of fish with atretic ovarian follicles were correctly classified using a discriminant function analysis based upon plasma testosterone concentrations. Logistic regression models were developed to predict the probability of normal ovaries based on plasma concentrations of sex steroids and can be further refined to improve selection of fish with normal ovaries for caviar harvest.
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rapid noninvasive characterization of ovarian follicular atresia in cultured White Sturgeon acipenser transmontanus by near infrared spectroscopy
Aquaculture, 2011Co-Authors: Sarah A Servid, Mariah J Talbott, Joel P Van Eenennaam, Serge I Doroshov, Peter Struffenegger, Molly A H Webb, Anna G CavinatoAbstract:Abstract We report a rapid and noninvasive method based on short wavelength near infrared (SW-NIR) spectroscopy to detect onset of atresia in farmed White Sturgeon ( Acipenser transmontanus ) (N = 10). The only current means to assess follicular atresia is by direct oocyte examination which requires a surgical biopsy of the ovary. In this study, abdominal scans were collected noninvasively by SW-NIR on anesthetized females using a diffuse reflectance fiber optic probe. In addition, to further verify the ability to detect spectroscopical changes related to onset of atresia, during each sampling roughly 30 cm 3 of ovarian follicles was surgically removed from each female and transferred to a Teflon holder for spectral acquisition. Comparison of spectra collected on normal or atretic fish or ovarian follicles was conducted using Principal Component Analysis (PCA). Principal components suggest that the best indicator of atresia onset is a decrease in the intensity of the lipid bands at 930 nm. Prediction models for atresia were constructed using Soft Independent Modeling of Class Analogy (SIMCA) with leave-one-out cross validation. Seventy one percent of all atretic spectra and 65% of normal spectra collected on ovarian follicles were correctly classified. Exclusion of spectra from two potential outlier fish improved the predictability of normal ovarian follicles to 76%. Similarly, 72% of all atretic spectra and 59% of all normal spectra collected noninvasively in whole fish were correctly classified. Exclusion from the model of spectra from the same two outlier fish improved prediction of atresia from 72% to 75% as well as improving the prediction of normal spectra from 59% to 62%. This study represents the first example of using a noninvasive approach based on SW-NIR to detect onset of atresia in female Sturgeon. Upon further development, this approach may potentially replace the need for surgical biopsy to detect ovarian regression. The availability of the proposed spectroscopic approach would grant Sturgeon growers a powerful tool to follow more closely the maturation cycle with the goal of producing a consistently uniform product, standardize processing conditions, and maximize caviar yield by harvesting fish when the ovarian follicles have the appropriate firmness and a larger size.
Esteban Soto - One of the best experts on this subject based on the ideXlab platform.
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outbreaks of severe myositis in cultured White Sturgeon acipenser transmontanus l associated with streptococcus iniae
Journal of Fish Diseases, 2020Co-Authors: Felipe Pierezan, Khalid Shahin, Taylor I Heckman, June Ang, Barbara A Byrne, Esteban SotoAbstract:Outbreaks of an infectious disease affecting cultured White Sturgeon (Acipenser transmontanus) were investigated. Clinical signs included erratic swimming, arching of the back and mortality. Necropsy findings included poorly demarcated yellow to dark-red and friable lesions in the epaxial muscle, ulcerative skin lesions and haemorrhages in the swim bladder and coelomic wall. Histological evaluation revealed areas of necrotizing and heterophilic myositis with aggregates of bacterial cocci. The lumen of blood vessels in the dermis, under ulcerated areas, and in the posterior kidney, was occluded by fibrin thrombi. Aggregates of Gram-positive cocci were observed in the muscle lesions and within the fibrin thrombi in the dermis and kidney. Genetically homogeneous Streptococcus iniae strains were recovered from affected fish from different outbreaks. The isolates shared high degree of similarity at gene locus (gyrB) with previously characterized S. iniae from cultured fish in California, confirming the emergence of this particular strain of S. iniae in US aquaculture.
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Effects of temperature on Veronaea botryosa infections in White Sturgeon Acipenser transmontanus and fungal induced cytotoxicity of fish cell lines
Veterinary Research, 2018Co-Authors: Denver J. Coleman, Alvin C. Camus, Beatriz Martínez-lópez, Susan Yun, Brittany Stevens, Esteban SotoAbstract:AbstractVeronaea botryosa is a melanized mold and cause of systemic fungal infections in cultured Sturgeon (Acipenser spp.). Mortality in adult female Sturgeon caused by this emergent pathogen results in significant economic losses for the caviar industry. Little is known regarding environmental conditions conducive to V. botryosa infection. This study evaluated the effect of temperature on V. botryosa infectivity and dissemination following intramuscular injection challenge of White Sturgeon maintained at 13 or 18 °C for 40 days. Daily mortality was recorded and persistence of the fungus in the livers of moribund and surviving fish was investigated using culture and histopathological analysis. Fish maintained at 18 °C developed systemic phaeohyphomycosis and had significantly greater mortality than controls and fish maintained at 13 °C (p
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co infection of acipenserid herpesvirus 2 acihv 2 and streptococcus iniae in cultured White Sturgeon acipenser transmontanus
Diseases of Aquatic Organisms, 2017Co-Authors: Esteban Soto, Susan Yun, Christine Richey, Brittany N Stevens, Kirsten Kenelty, Stephen R Reichley, Matt J Griffin, Tomofumi Kurobe, A CamusAbstract:A mortality event in cultured White Sturgeon Acipenser transmontanus (Richardson, 1836) sub-adults was investigated. After transfer between farms, high mortality was observed in fish, associated with back arching, abnormal swimming, and ulcerative skin lesions. Necropsy of moribund individuals revealed hemorrhagic ascites and petechial hemorrhages in the coelomic peritoneum and serosa of internal organs. Acipenserid herpesvirus 2 (AciHV-2) was isolated from external tissue samples, then identified and genotyped by sequencing of the terminase and polymerase genes. In addition, Streptococcus iniae was recovered from internal organs of affected fish. Histologic changes were limited to interstitial hematopoietic areas of the kidney and consisted of small foci of necrosis accompanied by fibrin deposition, minimal inflammatory response, and small numbers of bacterial cocci compatible with streptococci. Identity was confirmed by partial sequencing of the 16S rRNA, rpoB, and gyrB genes. Genetic fingerprinting demonstrated a genetic profile distinct from S. iniae isolates recovered from previous outbreaks in wild and cultured fish in North America, South America, and the Caribbean. Although the isolates were resistant to White Sturgeon complement in serum killing assays, in vivo challenges failed to fulfill Koch's postulates. However, the clinical presentation, coupled with consistent recovery of S. iniae and AciHV-2 from moribund fish, suggests viral and bacterial co-infection were the proximate cause of death. To our knowledge, this represents the first report of AciHV-2 and S. iniae co-infection in cultured White Sturgeon.
Seunghyung Lee - One of the best experts on this subject based on the ideXlab platform.
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effects of feed restriction on the upper temperature tolerance and heat shock response in juvenile green and White Sturgeon
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2016Co-Authors: Seunghyung Lee, Silas S O Hung, Liran Y Haller, Nann A Fangue, Christine E Verhille, Juan Zhao, Anne E TodghamAbstract:The objective of the current study was to investigate the effects of feed restriction on whole-organism upper thermal tolerance and the heat shock response of green and White Sturgeon to determine how changes in food amount might influence physiological performance of each species when faced with temperature stress. Two parallel feed restriction trials were carried out for juvenile green (202g; 222-day post hatch: dph) and White Sturgeon (205g; 197-dph) to manipulate nutritional status at 12.5%, 25%, 50%, or 100% of optimum feeding rate (100% OFR were 1.6% and 1.8% body weight/day, respectively) for four weeks. Following the trials, the critical thermal maximum (CTMax, 0.3°C/min) of Sturgeon (N=12/treatment/species) was assessed as an indicator of whole-organism upper thermal tolerance. To assess temperature sensitivity, Sturgeon (N=9/treatment/species) were acutely transferred to two temperature treatments (28°C and 18°C as a handling control) for 2h followed by 2h of recovery at 18°C before being sacrificed, and gill, brain, and mucus sampled for measurements of 70-kDa heat shock protein levels (Hsc/Hsp70). Feeding rate had species-specific effects on CTMax in green and White Sturgeon such that CTMax of green Sturgeon decreased as the magnitude of feed restriction increased; whereas, CTMax of White Sturgeon did not change with feed restriction. Elevated temperature (28°C) and feed restriction increased Hsc/Hsp70 levels in the gill tissue of green Sturgeon, while heat shock increased Hsc/Hsp70 levels in the mucus of White Sturgeon. Our results suggest that green Sturgeon may be more susceptible to temperature stress under food-limited conditions.
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effects of feeding rate on growth performance and nutrient partitioning of young of the year White Sturgeon acipenser transmontanus
Aquaculture Nutrition, 2016Co-Authors: Seunghyung Lee, Liran Y Haller, Nann A Fangue, J G Fadel, Silas S O HungAbstract:A 10-week growth trial was performed to evaluate the effects of feeding rate on growth performance, nutrient partitioning, and to determine the optimum feeding rate for young-of-the-year White Sturgeon. Three tanks with 30 fish per tank each were assigned to five feeding rates, 0.4–2.0% body weight per day (BW day−1). Weight gain significantly (P < 0.05) increased with increasing feeding rate up to 1.2% BW day−1. Feed efficiency exhibited an inverse relationship to weight gain. Hepatosomatic and gonadal-fat-body (GFB)-somatic indices were significantly affected by feeding rate, and the lowest values were observed at 0.4% BW day−1. The increased feeding rate significantly affected whole-body and carcass lipid and moisture contents. Protein gain in the carcass, but not in the GFB, was significantly influenced by feeding rate. Lipid gain in the carcass and GFB was also significantly affected by feeding rate. Four regression models were tested for the estimation of optimum feeding rate, including one-slope straight broken-line, two-slope straight broken-line, quadratic broken-line and quadratic models. Adjusted coefficient of correlation and corrected Akaike information criterion were used to compare model performance. The quadratic broken-line model was chosen as the best based on the criteria. The estimated optimum feeding rate for young-of-the-year White Sturgeon (360 g) is 1.5% BW day−1.
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Responses of heat shock protein 70 and caspase-3/7 to dietary selenomethionine in juvenile White Sturgeon
KeAi, 2016Co-Authors: Weifang Wang, Silas S O Hung, Seunghyung Lee, Dongfang DengAbstract:An 8-week feeding trial was conducted to investigate the responses of juvenile White Sturgeon (Acipenser transmontanus) to elevated dietary selenium (Se) based on the determination of the RNA/DNA ratio in muscle, heat shock protein 70 (Hsp70), and caspase-3/7 in muscle and/or liver tissues. Four semi-purified test diets were prepared by adding different levels of L-selenomethionine (0, 50, 100, and 200 mg/kg diet). The analytical determinations of total Se were 2.2, 19.7, 40.1, and 77.7 mg/kg diet. The Sturgeon (initial body weight: 30 ± 2 g; mean ± SEM) were raised in indoor tanks provided with flow through freshwater (18–19 °C). There were three replicates for each dietary treatment with 25 fish per replicate. The liver and muscle tissues were collected at 4 and 8 weeks after feeding the test diets. A significant interaction between duration and levels of dietary Se exposures on RNA/DNA ratio in the muscle tissue was detected (P
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development of optimum feeding rate model for White Sturgeon acipenser transmontanus
Aquaculture, 2014Co-Authors: Seunghyung Lee, Silas S O Hung, Nann A Fangue, Yichuan Wang, A B Strathe, J G FadelAbstract:Abstract Establishing the optimum feeding rate (OFR; % body weight per day) for a cultured fish is a significant step toward the success of the aquaculture operation. Therefore, the objectives of this study were 1) the estimation of OFR for 19 datasets with different initial body weights by applying broken-line and quadratic regression models and 2) an investigation of potential OFR prediction models using 19 estimated OFRs from objective 1. Objective 1) Nineteen datasets were obtained from five published studies (14 datasets) and one unpublished study (5 datasets) which were carried out to evaluate the effects of feeding rate on growth performance in White Sturgeon of initial body weights varying from 0.05 g to 764 g. Each dataset, containing feeding rate (independent variable) and specific growth rate (% body weight increase per day; dependent variable) was used to estimate OFR by one-slope straight broken-line, two-slope straight broken-line, quadratic broken-line, and quadratic models for each body weight class. Calculations of model selection criteria, including the adjusted coefficient of correlation, Akaike information criterion, and corrected Akaike information criterion were performed to compare model performance on OFR estimation for each dataset. Three models (two-slope straight broken-line, quadratic broken-line, and quadratic models) were considered acceptable for the estimation of OFR, and the three sets of estimated OFRs obtained by these models were used in objective 2. Objective 2) Several regression models, including polynomial models of order from 1 to 6, a simple exponential model with a constant, and a bi-exponential model, were fitted to each set of the 19 estimated OFRs against transformed initial body weights. A power function model was also fitted to the estimated OFRs against untransformed initial body weights. The model selection criteria for objective 2 were the same as those for objective 1. Overall model performance on the estimation of OFR for the 19 datasets shows that the quadratic broken-line model performed best, followed by the quadratic, two-slope straight broken-line, and one-slope straight broken-line models. Given the overall performance of model fitness to the sets of the OFR estimates, the bi-exponential regression model emerged as the most favorable one. As a result, the bi-exponential model equation. OFR % body weight per day = 0.00344 ± 0.0123 e − 5.684 ± 2.309 ln ( body weight ) + 8.695 ± 0.606 e − 0.549 ± 0.065 ln ( body weight ) obtained by fitting the estimated OFRs derived from the quadratic broken-line model analysis, can be used to predict the OFR for White Sturgeon from about 0.05 g to 800 g.
