The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Paul K Hershberger - One of the best experts on this subject based on the ideXlab platform.
-
Optimization of a Plaque Neutralization Test (PNT) to Identify the Exposure History of Pacific Herring to Viral Hemorrhagic Septicemia Virus (VHSV).
Journal of aquatic animal health, 2017Co-Authors: Lucas M. Hart, Maureen K. Purcell, Ashley Mackenzie, Rachel L. Powers, Paul K HershbergerAbstract:Methods for a plaque neutralization test (PNT) were optimized for the detection and quantification of viral hemorrhagic septicemia virus (VHSV) neutralizing activity in the plasma of Pacific Herring Clupea pallasii. The PNT was complement dependent, as neutralizing activity was attenuated by heat inactivation; further, neutralizing activity was mostly restored by the addition of exogenous complement from specific-pathogen-free Pacific Herring. Optimal methods included the overnight incubation of VHSV aliquots in serial dilutions (starting at 1:16) of whole test plasma containing endogenous complement. The resulting viral titers were then enumerated using a viral plaque assay in 96-well microplates. Serum neutralizing activity was virus-specific as plasma from viral hemorrhagic septicemia (VHS) survivors demonstrated only negligible reactivity to infectious hematopoietic necrosis virus, a closely related rhabdovirus. Among Pacific Herring that survived VHSV exposure, neutralizing activity was detected in the plasma as early as 37 d postexposure and peaked at approximately 64 d postexposure. The onset of neutralizing activity was slightly delayed in fish reared at 7.4°C relative to those in warmer temperatures (9.9°C and 13.1°C); however, neutralizing activity persisted for at least 345 d postexposure in all temperature treatments. It is anticipated that this novel ability to assess VHSV neutralizing activity in Pacific Herring will enable retrospective comparisons between prior VHS infections and year-class recruitment failures. Additionally, the optimized PNT could be employed as a forecasting tool capable of identifying the potential for future VHS epizootics in wild Pacific Herring populations. Received November 7, 2016; accepted January 14, 2017.
-
The parasite Ichthyophonus sp. in Pacific Herring from the coastal NE Pacific.
Journal of fish diseases, 2015Co-Authors: Paul K Hershberger, Jacob L Gregg, Lucas M. Hart, Johanna J. Vollenweider, Steve Moffitt, Richard L. Brenner, K. Stick, Eric Coonradt, E. O. Otis, Kyle A. GarverAbstract:The protistan parasite Ichthyophonus occurred in populations of Pacific Herring Clupea pallasii Valenciennes throughout coastal areas of the NE Pacific, ranging from Puget Sound, WA north to the Gulf of Alaska, AK. Infection prevalence in local Pacific Herring stocks varied seasonally and annually, and a general pattern of increasing prevalence with host size and/or age persisted throughout the NE Pacific. An exception to this zoographic pattern occurred among a group of juvenile, age 1+ year Pacific Herring from Cordova Harbor, AK in June 2010, which demonstrated an unusually high infection prevalence of 35%. Reasons for this anomaly were hypothesized to involve anthropogenic influences that resulted in locally elevated infection pressures. Interannual declines in infection prevalence from some populations (e.g. Lower Cook Inlet, AK; from 20-32% in 2007 to 0-3% during 2009-13) or from the largest size cohorts of other populations (e.g. Sitka Sound, AK; from 62.5% in 2007 to 19.6% in 2013) were likely a reflection of selective mortality among the infected cohorts. All available information for Ichthyophonus in the NE Pacific, including broad geographic range, low host specificity and presence in archived Pacific Herring tissue samples dating to the 1980s, indicate a long-standing host-pathogen relationship.
-
Molecular identification of erythrocytic necrosis virus (ENV) from the blood of Pacific Herring (Clupea pallasii).
Veterinary microbiology, 2014Co-Authors: Eveline J Emmenegger, Jacob L Gregg, James R. Winton, William N. Batts, Jolene A Glenn, Paul K HershbergerAbstract:Viral erythrocytic necrosis (VEN) is a condition affecting the red blood cells of more than 20 species of marine and anadromous fishes in the North Atlantic and North Pacific Oceans. Among populations of Pacific Herring (Clupea pallasii) on the west coast of North America the disease causes anemia and elevated mortality in periodic epizootics. Presently, VEN is diagnosed by observation of typical cytoplasmic inclusion bodies in stained blood smears from infected fish. The causative agent, erythrocytic necrosis virus (ENV), is unculturable and a presumed iridovirus by electron microscopy. In vivo amplification of the virus in pathogen-free laboratory stocks of Pacific Herring with subsequent virus concentration, purification, DNA extraction, and high-throughput sequencing were used to obtain genomic ENV sequences. Fragments with the highest sequence identity to the family Iridoviridae were used to design four sets of ENV-specific polymerase chain reaction (PCR) primers. Testing of blood and tissue samples from experimentally and wild infected Pacific Herring as well as DNA extracted from other amphibian and piscine iridoviruses verified the assays were specific to ENV with a limit of detection of 0.0003 ng. Preliminary phylogenetic analyses of a 1448 bp fragment of the putative DNA polymerase gene supported inclusion of ENV in a proposed sixth genus of the family Iridoviridae that contains other erythrocytic viruses from ectothermic hosts. This study provides the first molecular evidence of ENV's inclusion within the Iridoviridae family and offers conventional PCR assays as a means of rapidly surveying the ENV-status of wild and propagated Pacific Herring stocks.
-
Viability and Infectivity of Ichthyophonus sp. in Post-Mortem Pacific Herring, Clupea pallasii
The Journal of parasitology, 2014Co-Authors: Richard M. Kocan, Lucas M. Hart, Naomi Lewandowski, Paul K HershbergerAbstract:Abstract: Ichthyophonus-infected Pacific Herring, Clupea pallasii, were allowed to decompose in ambient seawater then serially sampled for 29 days to evaluate parasite viability and infectivity for Pacific staghorn sculpin, Leptocottus armatus. Ichthyophonus sp. was viable in decomposing Herring tissues for at least 29 days post-mortem and could be transmitted via ingestion to sculpin for up to 5 days. The parasite underwent morphologic changes during the first 48 hr following death of the host that were similar to those previously reported, but as host tissue decomposition progressed, several previously un-described forms of the parasite were observed. The significance of long-term survival and continued morphologic transformation in the post-mortem host is unknown, but it could represent a saprozoic phase of the parasite life cycle that has survival value for Ichthyophonus sp.
-
Influence of temperature on viral hemorrhagic septicemia (Genogroup IVa) in Pacific Herring, Clupea pallasii Valenciennes☆
Journal of Experimental Marine Biology and Ecology, 2013Co-Authors: Paul K Hershberger, Maureen K. Purcell, Lucas M. Hart, Rachel L. Thompson, Kyle A. Garver, James R. WintonAbstract:Abstract An inverse relationship between water temperature and susceptibility of Pacific Herring ( Clupea pallasii ) to viral hemorrhagic septicemia, genogroup IVa (VHS) was indicated by controlled exposure studies where cumulative mortalities, viral shedding rates, and viral persistence in survivors were greatest at the coolest exposure temperatures. Among groups of specific pathogen-free (SPF) Pacific Herring maintained at 8, 11, and 15 °C, cumulative mortalities after waterborne exposure to viral hemorrhagic septicemia virus (VHSV) were 78%, 40%, and 13%, respectively. The prevalence of survivors with VHSV-positive tissues 25 d post-exposure was 64%, 16%, and 0% (at 8, 11 and 15 °C, respectively) with viral prevalence typically higher in brain tissues than in kidney/spleen tissue pools at each temperature. Similarly, geometric mean viral titers in brain tissues and kidney/spleen tissue pools decreased at higher temperatures, and kidney/spleen titers were generally 10-fold lower than those in brain tissues at each temperature. This inverse relationship between temperature and VHS severity was likely mediated by an enhanced immune response at the warmer temperatures, where a robust type I interferon response was indicated by rapid and significant upregulation of the Herring Mx gene. The effect of relatively small temperature differences on the susceptibility of a natural host to VHS provides insights into conditions that preface periodic VHSV epizootics in wild populations throughout the NE Pacific.
James R. Winton - One of the best experts on this subject based on the ideXlab platform.
-
Molecular identification of erythrocytic necrosis virus (ENV) from the blood of Pacific Herring (Clupea pallasii).
Veterinary microbiology, 2014Co-Authors: Eveline J Emmenegger, Jacob L Gregg, James R. Winton, William N. Batts, Jolene A Glenn, Paul K HershbergerAbstract:Viral erythrocytic necrosis (VEN) is a condition affecting the red blood cells of more than 20 species of marine and anadromous fishes in the North Atlantic and North Pacific Oceans. Among populations of Pacific Herring (Clupea pallasii) on the west coast of North America the disease causes anemia and elevated mortality in periodic epizootics. Presently, VEN is diagnosed by observation of typical cytoplasmic inclusion bodies in stained blood smears from infected fish. The causative agent, erythrocytic necrosis virus (ENV), is unculturable and a presumed iridovirus by electron microscopy. In vivo amplification of the virus in pathogen-free laboratory stocks of Pacific Herring with subsequent virus concentration, purification, DNA extraction, and high-throughput sequencing were used to obtain genomic ENV sequences. Fragments with the highest sequence identity to the family Iridoviridae were used to design four sets of ENV-specific polymerase chain reaction (PCR) primers. Testing of blood and tissue samples from experimentally and wild infected Pacific Herring as well as DNA extracted from other amphibian and piscine iridoviruses verified the assays were specific to ENV with a limit of detection of 0.0003 ng. Preliminary phylogenetic analyses of a 1448 bp fragment of the putative DNA polymerase gene supported inclusion of ENV in a proposed sixth genus of the family Iridoviridae that contains other erythrocytic viruses from ectothermic hosts. This study provides the first molecular evidence of ENV's inclusion within the Iridoviridae family and offers conventional PCR assays as a means of rapidly surveying the ENV-status of wild and propagated Pacific Herring stocks.
-
Influence of temperature on viral hemorrhagic septicemia (Genogroup IVa) in Pacific Herring, Clupea pallasii Valenciennes☆
Journal of Experimental Marine Biology and Ecology, 2013Co-Authors: Paul K Hershberger, Maureen K. Purcell, Lucas M. Hart, Rachel L. Thompson, Kyle A. Garver, James R. WintonAbstract:Abstract An inverse relationship between water temperature and susceptibility of Pacific Herring ( Clupea pallasii ) to viral hemorrhagic septicemia, genogroup IVa (VHS) was indicated by controlled exposure studies where cumulative mortalities, viral shedding rates, and viral persistence in survivors were greatest at the coolest exposure temperatures. Among groups of specific pathogen-free (SPF) Pacific Herring maintained at 8, 11, and 15 °C, cumulative mortalities after waterborne exposure to viral hemorrhagic septicemia virus (VHSV) were 78%, 40%, and 13%, respectively. The prevalence of survivors with VHSV-positive tissues 25 d post-exposure was 64%, 16%, and 0% (at 8, 11 and 15 °C, respectively) with viral prevalence typically higher in brain tissues than in kidney/spleen tissue pools at each temperature. Similarly, geometric mean viral titers in brain tissues and kidney/spleen tissue pools decreased at higher temperatures, and kidney/spleen titers were generally 10-fold lower than those in brain tissues at each temperature. This inverse relationship between temperature and VHS severity was likely mediated by an enhanced immune response at the warmer temperatures, where a robust type I interferon response was indicated by rapid and significant upregulation of the Herring Mx gene. The effect of relatively small temperature differences on the susceptibility of a natural host to VHS provides insights into conditions that preface periodic VHSV epizootics in wild populations throughout the NE Pacific.
-
Susceptibility of Pacific Herring to viral hemorrhagic septicemia is influenced by diet
Journal of aquatic animal health, 2012Co-Authors: J. Beaulaurier, C A Grady, James R. Winton, Nathaniel A Bickford, A. L. Gannam, Paul K HershbergerAbstract:Abstract Groups of specific-pathogen-free Pacific Herring Clupea pallasii were highly susceptible to infection by viral hemorrhagic septicemia virus (VHSV); however, the level of mortality was influenced by diet during the 40–71 d before, during, and after the first exposure to the virus. Cumulative mortality was highest among the Herring maintained on an experimental soy-based pellet, intermediate among those maintained on a commercially available fish-meal-based pellet, and lowest among those maintained on a second commercially available fish-meal-based pellet containing β-glucans. Additionally, the Herring maintained on the experimental soy-based feed demonstrated less growth than those on the commercially available feeds. The results indicate the importance of standardizing diet during empirical determinations of disease susceptibility and provide insights into the risk factors affecting VHS susceptibility in wild populations. Received August 26, 2011; accepted November 4, 2011
-
Passive Immunization of Pacific Herring against Viral Hemorrhagic Septicemia
Journal of aquatic animal health, 2011Co-Authors: Paul K Hershberger, Jacob L Gregg, C A Grady, Scott E. Lapatra, James R. WintonAbstract:Abstract The plasma of Pacific Herring Clupea pallasii that survived laboratory-induced viral hemorrhagic septicemia (VHS) epizootics contained humoral substances that, when injected into naive animals, conferred passive immunity against the disease. Among groups exposed to viral hemorrhagic septicemia virus (VHSV), injection of donor plasma from VHS survivors resulted in significantly greater survival (50%) and significantly lower tissue titers (1.5 × 105 plaque-forming units [PFU]/g) than the injection of plasma from VHSV-naive donors (6% survival; 3.7 × 106 PFU/g). Additionally, the magnitude of the protective immune response increased during the postexposure period; plasma that was collected from survivors at 123 d postexposure (931 degree-days) provided greater protection than plasma collected from survivors at 60 d postexposure (409 degree-days). These results provide proof of concept that the VHSV exposure history of Pacific Herring populations can be determined post hoc; furthermore, the results c...
-
Chronic and persistent viral hemorrhagic septicemia virus infections in Pacific Herring.
Diseases of aquatic organisms, 2010Co-Authors: Paul K Hershberger, C A Grady, L. Taylor, James R. WintonAbstract:Chronic viral hemorrhagic septicemia virus (VHSV) infections were established in a lab- oratory stock of Pacific Herring Clupea pallasii held in a large-volume tank supplied with pathogen- free seawater at temperatures ranging from 6.8 to 11.6°C. The infections were characterized by viral persistence for extended periods and near-background levels of host mortality. Infectious virus was recovered from mortalities occurring up to 167 d post-exposure and was detected in normal-appear- ing Herring for as long as 224 d following initial challenge. Geometric mean viral titers were gener- ally as high as or higher in brain tissues than in pools of kidney and spleen tissues, with overall preva- lence of infection being higher in the brain. Upon re-exposure to VHSV in a standard laboratory challenge, negligible mortality occurred among groups of Herring that were either chronically infected or fully recovered, indicating that survival from chronic manifestations conferred protection against future disease. However, some survivors of chronic VHS infections were capable of replicat- ing virus upon re-exposure. Demonstration of a chronic manifestation of VHSV infection among Pacific Herring maintained at ambient seawater temperatures provides insights into the mechanisms by which the virus is maintained among populations of endemic hosts.
Timothy E. Essington - One of the best experts on this subject based on the ideXlab platform.
-
evaluating hypoxia inducible factor 1α mrna expression in a pelagic fish Pacific Herring clupea pallasii as a biomarker for hypoxia exposure
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2015Co-Authors: Halley E Froehlich, Steven B Roberts, Timothy E. EssingtonAbstract:Abstract Hypoxia [dissolved oxygen (DO) − 1 ] is a major environmental perturbation for many aquatic ecosystems, particularly highly productive estuaries. Most research attention and understanding about the impacts of hypoxia on estuarine species has focused on the benthos, where hypoxia is most common. Although the pelagic zone is also susceptible to the effects of hypoxia, the biological interactions and consequences are not as well understood in marine environments because documenting exposure or avoidance of hypoxia is often difficult. Physiological biomarkers may provide a way to gain more detailed spatiotemporal information regarding species' exposure to hypoxia. Here, we identified and tested a hypoxia-specific responsive gene, hypoxia-inducible factor-1α (hif-1α), to evaluate its potential as a biomarker for hypoxia exposure in Pacific Herring ( Clupea pallasii ). We conducted controlled laboratory experiments to establish the level of hepatic hif-1α elevated gene expression (> 1 sd normoxic mean), exposure amplification (≥ 2 hours), reduction rate (ca. 24 hours), and some evidence of a lethal hypoxic limit (ca. 2 mg L − 1 , ≥ 4 hours). We then used these findings to evaluate the spatiotemporal patterns of hif-1α for Pacific Herring in a seasonally hypoxia estuary, Hood Canal, Washington, USA. Although expression did not parallel the local hypoxic conditions in the estuary, Herring from the more severe hypoxic year (2013) had a higher probability of having elevated mRNA levels. These patterns indicate that hepatic hif-1α levels may not be directly indicative of local DO levels for pelagic marine fish, but rather provide insight into hypoxia exposure over broader scales.
-
evaluating hypoxia inducible factor 1α mrna expression in a pelagic fish Pacific Herring clupea pallasii as a biomarker for hypoxia exposure
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2015Co-Authors: Halley E Froehlich, Steven B Roberts, Timothy E. EssingtonAbstract:Hypoxia [dissolved oxygen (DO) 1 sd normoxic mean), exposure amplification (≥2 hours), reduction rate (ca. 24 hours), and some evidence of a lethal hypoxic limit (ca. 2 mg L(-1), ≥4 hours). We then used these findings to evaluate the spatiotemporal patterns of hif-1α for Pacific Herring in a seasonally hypoxia estuary, Hood Canal, Washington, USA. Although expression did not parallel the local hypoxic conditions in the estuary, Herring from the more severe hypoxic year (2013) had a higher probability of having elevated mRNA levels. These patterns indicate that hepatic hif-1α levels may not be directly indicative of local DO levels for pelagic marine fish, but rather provide insight into hypoxia exposure over broader scales.
Gary D. Marty - One of the best experts on this subject based on the ideXlab platform.
-
Failure of population recovery in relation to disease in Pacific Herring.
Diseases of aquatic organisms, 2010Co-Authors: Gary D. Marty, Terrance J. Quinn, Peterjohn F Hulson, Sara E Miller, Steve D. Moffitt, Richard A. MerizonAbstract:Following an estimated 60% decline in population abundance in early 1993, recovery of the Pacific Herring Clupea pallasii population of Prince William Sound, Alaska, USA, has been impaired by disease. Comprehensive epidemiological study from 1994 through 2002 validated an age-structured assessment (ASA) model of disease and population abundance; from 2003 to 2006, the impact of disease was modeled by analyzing only 2 lesions: ulcers and white foci in the heart. The ASA model identified increased natural mortality since 1993 that can be explained by (1) epidemics associated with ulcers (prevalence about 3%) and the North American strain of viral hemorrhagic septicemia virus (VHSV Type IVa; prevalence up to 14%) in 1994 and 1998 and (2) relatively high prevalence of the mesomycetozoean Ichthyophonus hoferi from 1994 through 2006, including epi- demics with the greatest sample prevalence in 2001 (38%, by histopathology) and 2005 (51%, esti- mated histopathology prevalence). Fourteen other parasites occurred at prevalence >10%, but none were considered significant contributors to fish mortality. We predict that if natural mortality after 1994 had returned to background levels that best fit the model from 1980 to 1992 (0.25 yr -1 ), popula- tion biomass in 2006 would have been 3 times the best estimate, despite relatively poor recruitment since 1994. In conclusion, disease information can be used to explain and predict changes in popula- tions that have confounded traditional fisheries assessment.
-
data conflicts in fishery models incorporating hydroacoustic data into the prince william sound Pacific Herring assessment model
Ices Journal of Marine Science, 2008Co-Authors: Peterjohn F Hulson, Gary D. Marty, Terrance J. Quinn, Sara E Miller, Steven D Moffitt, Frederick FunkAbstract:Hulson, P-J. F., Miller, S. E., Quinn, T. J. II, Marty, G. D., Moffitt, S. D., and Funk, F. 2008. Data conflicts in fishery models: incorporating hydroacoustic data into the Prince William Sound Pacific Herring assessment model. - ICES Journal of Marine Science, 65: 25-43.Data conflicts present difficulties in running integrated assessment models as shown by the age-structured assessment (ASA) model for the Pacific Herring population in Prince William Sound (PWS), Alaska. After the 1989 “Exxon Valdez” oil spill in PWS, the Pacific Herring (Clupea pallasi) ASA model indicated a significant decline in the population, starting in winter 1992. Back-calculated estimates from hydroacoustic abundance surveys that started in 1993 suggested that the ASA model overestimated Herring biomass from 1990 to 1992 and that the population decline actually began in 1989. To expose data conflicts, we incorporated the hydroacoustic survey information with all available spawning population indices directly into the age-structured model. In this way, the substantial uncertainty about population parameters from 1989 to 1992 attributable to data conflicts was quantified. Consequently, the magnitude of declines for that period estimated from both linear and ASA models depend on the type of integrated datasets and weighting, particularly with indices of male spawners. Our view is that a major decline started in 1992 when disease affected a large population that was in weakened condition. Other views are consistent with the existing data too.
-
Role of disease in abundance of a Pacific Herring (Clupea pallasi) population
Canadian Journal of Fisheries and Aquatic Sciences, 2003Co-Authors: Gary D. Marty, T R Meyers, Terrance J. Quinn, Greg Carpenter, Neil H. WillitsAbstract:Disease significantly affects population abundance of Pacific Herring (Clupea pallasi). Comprehensive epidemiological study of the Pacific Herring population of Prince William Sound, Alaska, U.S.A., from 1994 to 2000 included complete necropsy examination of 230500 fish each spring and 40160 fish each fall (total n = 2983 fish). Mortality is best estimated, through modifications of an age-structured assessment model, using a disease index that combines the prevalence of viral hemorrhagic septicemia virus (VHSV) with the prevalence of ulcers. Risk factors for an epidemic include poor body condition and abundant recruitment before spawning in the spring. Prevalence of the pathogen Ichthyophonus hoferi increased as fish aged, but changes in I. hoferi prevalence were not related to changes in population abundance. Disease that caused an epidemic in 1998 (VHSV and ulcers) nearly disappeared from the population when changes in abundance were detected by traditional stock assessment methods in 1999. Disease si...
-
Synthesis of the toxicological impacts of the Exxon Valdez oil spill on Pacific Herring (Clupea pallasi) in Prince William Sound, Alaska, U.S.A.
Canadian Journal of Fisheries and Aquatic Sciences, 2002Co-Authors: Mark G. Carls, Gary D. Marty, Jo Ellen HoseAbstract:Pacific Herring (Clupea pallasi) in Prince William Sound (PWS) were affected by two major events in the past decade: the Exxon Valdez oil spill in 1989 and a 75% collapse in the adult population in...
-
viral hemorrhagic septicemia virus ichthyophonus hoferi and other causes of morbidity in Pacific Herring clupea pallasi spawning in prince william sound alaska usa
Diseases of Aquatic Organisms, 1998Co-Authors: Gary D. Marty, T R Meyers, Ellen F Freiberg, John Wilcock, Thomas B Farver, David E HintonAbstract:Pacific Herring Clupea pallasi populations in Prince William Sound, Alaska, USA, declined from an estimated 9.8 x 10(7) kg in 1992 to 1.5 x 10(7) kg in 1994. To determine the role of disease in population decline, 233 Pacific Herring from Prince William Sound were subjected to complete necropsy during April 1994. The North American strain of viral hemorrhagic septicemia virus (VHSV) was isolated from 11 of 233 fish (4.7%). VHSV was significantly related to myocardial mineralization, hepatocellular necrosis, submucosal gastritis, and meningoencephalitis. Ichthyophonus hoferi infected 62 of 212 (29%) fish. I. hoferi infections were associated with severe, disseminated, granulomatous inflammation and with increased levels of plasma creatine phosphokinase (CPK) and aspartate aminotransferase (AST). I. hoferi prevalence in 1994 was more than double that of most previous years (1989 to 1993). Plasma chemistry values significantly greater (p < 0.01) in males than females included albumin, total protein, cholesterol, chloride, glucose, and potassium; only alkaline phosphatase was significantly greater in females. Hypoalbuminemia was relatively common in postspawning females; other risk factors included VHSV and moderate or severe focal skin reddening. Pacific Herring had more than 10 species of parasites, but they were not associated with significant lesions. Two of the parasites have not previously been described: a renal intraductal myxosporean (11% prevalence) and an intestinal coccidian (91% prevalence). Transmission electron microscopy of a solitary mesenteric lesion revealed viral particles consistent with lymphocystis virus. No fish had viral erythrocytic necrosis (VEN). Prevalence of external gross lesions and major parasites was not related to fish age, and fish that were year-lings at the time of the 1989 'Exxon Valdez' oil spill (1988 year class) had no evidence of increased disease prevalence.
Halley E Froehlich - One of the best experts on this subject based on the ideXlab platform.
-
evaluating hypoxia inducible factor 1α mrna expression in a pelagic fish Pacific Herring clupea pallasii as a biomarker for hypoxia exposure
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2015Co-Authors: Halley E Froehlich, Steven B Roberts, Timothy E. EssingtonAbstract:Abstract Hypoxia [dissolved oxygen (DO) − 1 ] is a major environmental perturbation for many aquatic ecosystems, particularly highly productive estuaries. Most research attention and understanding about the impacts of hypoxia on estuarine species has focused on the benthos, where hypoxia is most common. Although the pelagic zone is also susceptible to the effects of hypoxia, the biological interactions and consequences are not as well understood in marine environments because documenting exposure or avoidance of hypoxia is often difficult. Physiological biomarkers may provide a way to gain more detailed spatiotemporal information regarding species' exposure to hypoxia. Here, we identified and tested a hypoxia-specific responsive gene, hypoxia-inducible factor-1α (hif-1α), to evaluate its potential as a biomarker for hypoxia exposure in Pacific Herring ( Clupea pallasii ). We conducted controlled laboratory experiments to establish the level of hepatic hif-1α elevated gene expression (> 1 sd normoxic mean), exposure amplification (≥ 2 hours), reduction rate (ca. 24 hours), and some evidence of a lethal hypoxic limit (ca. 2 mg L − 1 , ≥ 4 hours). We then used these findings to evaluate the spatiotemporal patterns of hif-1α for Pacific Herring in a seasonally hypoxia estuary, Hood Canal, Washington, USA. Although expression did not parallel the local hypoxic conditions in the estuary, Herring from the more severe hypoxic year (2013) had a higher probability of having elevated mRNA levels. These patterns indicate that hepatic hif-1α levels may not be directly indicative of local DO levels for pelagic marine fish, but rather provide insight into hypoxia exposure over broader scales.
-
evaluating hypoxia inducible factor 1α mrna expression in a pelagic fish Pacific Herring clupea pallasii as a biomarker for hypoxia exposure
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2015Co-Authors: Halley E Froehlich, Steven B Roberts, Timothy E. EssingtonAbstract:Hypoxia [dissolved oxygen (DO) 1 sd normoxic mean), exposure amplification (≥2 hours), reduction rate (ca. 24 hours), and some evidence of a lethal hypoxic limit (ca. 2 mg L(-1), ≥4 hours). We then used these findings to evaluate the spatiotemporal patterns of hif-1α for Pacific Herring in a seasonally hypoxia estuary, Hood Canal, Washington, USA. Although expression did not parallel the local hypoxic conditions in the estuary, Herring from the more severe hypoxic year (2013) had a higher probability of having elevated mRNA levels. These patterns indicate that hepatic hif-1α levels may not be directly indicative of local DO levels for pelagic marine fish, but rather provide insight into hypoxia exposure over broader scales.
