ole nielsen | Fisheries and Oceans Canada (original) (raw)

Papers by ole nielsen

Research paper thumbnail of Epizootiology of Morbillivirus Infection in Harp, Hooded, and Ringed Seals from the Canadian Arctic and Western Atlantic

Journal of Wildlife Diseases, 1997

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Research paper thumbnail of Novel Poxvirus Infection in Northern and Southern Sea Otters (Enhydra Lutris Kenyoni and Enhydra Lutris Neiris), Alaska and California, Usa

Journal of Wildlife Diseases, 2014

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Research paper thumbnail of Brucellosis in Ringed Seals and Harp Seals from Canada

Journal of Wildlife Diseases, 2000

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Research paper thumbnail of Serologic Survey for Potential Pathogens and Assessment of Disease Risk in Australian Fur Seals

Journal of Wildlife Diseases, 2011

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Research paper thumbnail of Epizootiology of Brucella Infection in Australian Fur Seals

Journal of Wildlife Diseases, 2011

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Research paper thumbnail of Sequential cold-sensitive mutations in Aspergillus fumigatus . II. Analysis by the parasexual cycle

Canadian Journal of Microbiology, 1981

From Aspergillus fumigatus I-21 (ATCC 32722), which grows at temperatures from 12 to 50 °C, three... more From Aspergillus fumigatus I-21 (ATCC 32722), which grows at temperatures from 12 to 50 °C, three multistep, independently derived, cold-sensitive mutants unable to grow at 37 °C or below (Cs-37) were obtained by sequential exposure to ethylmethane sulfonate (strain AT2) or N-methyl-N′-nitro-N-nitrosoguanidine (AT1 and AT3). These mutants and ON5, a five-step Cs-37 mutant, were marked by mutations affecting spore color and nutritional requirements and crossed in four combinations by classical parasexual means.The heterokaryons demonstrated partial complementation with respect to auxotrophic requirements (suboptimal growth on minimal medium) and cold sensitivity (growth at 37 °C but not at 25 °C). Most presumed diploids, formed by exposure of the heterokaryons to d-camphor vapors, showed complete complementation but were unstable, as demonstrated by variations in spore sizes and markedly different ratios of segregant classes derived from different clones.Analysis of the segregants of...

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Research paper thumbnail of Streptococcus phocae in Marine Mammals of Northeastern Pacific and Arctic Canada: A Retrospective Analysis of 85 Postmortem Investigations

Journal of wildlife diseases, Jan 5, 2017

Streptococcus phocae is a pathogen of marine mammals, although its pathogenicity remains poorly u... more Streptococcus phocae is a pathogen of marine mammals, although its pathogenicity remains poorly understood. Recovery of this bacterium from asymptomatic carriers suggests that it is an opportunistic pathogen. We investigated the role of S. phocae in naturally occurring disease and its significance as a pathogen based on postmortem investigations. Between 2007 and 2012, 1,696 whole carcasses, tissue samples, or both were submitted from the northeastern Pacific and Arctic Canada for diagnostic testing. Streptococcus phocae was cultured from phocids (n=66), otariids (n=12), harbor porpoises (Phocoena phocoena; n=5), and sea otters (Enhydra lutris; n=2). Pathologic manifestations of S. phocae-associated disease included localized, as well as systemic, inflammatory lesions with common findings of suppurative bronchopneumonia (n=17) and bacteremia (n=27). Lung lesions were frequently culture-positive for S. phocae, suggesting commensal colonization of the oropharynx with subsequent opport...

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Research paper thumbnail of Demographic, ecological, and physiological responses of ringed seals to an abrupt decline in sea ice availability

PeerJ, 2017

To assess whether demographic declines of Arctic species at the southern limit of their range wil... more To assess whether demographic declines of Arctic species at the southern limit of their range will be gradual or punctuated, we compared large-scale environmental patterns including sea ice dynamics to ringed seal (Pusa hispida) reproduction, body condition, recruitment, and stress in Hudson Bay from 2003 to 2013. Aerial surveys suggested a gradual decline in seal density from 1995 to 2013, with the lowest density occurring in 2013. Body condition decreased and stress (cortisol) increased over time in relation to longer open water periods. The 2010 open water period in Hudson Bay coincided with extremes in large-scale atmospheric patterns (North Atlantic Oscillation, Arctic Oscillation, El Nino-Southern Oscillation) resulting in the earliest spring breakup and the latest ice formation on record. The warming event was coincident with high stress level, low ovulation rate, low pregnancy rate, few pups in the Inuit harvest, and observations of sick seals. Results provide evidence of ch...

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Research paper thumbnail of Saxitoxin increases phocine distemper virus replication upon in-vitro infection in harbor seal immune cells

Harmful Algae, 2016

Several marine mammal epizootics have been closely linked to infectious diseases, as well as to t... more Several marine mammal epizootics have been closely linked to infectious diseases, as well as to the biotoxins produced by harmful algal blooms (HABs). In two of three saxitoxin (STX) associated mortality events, dolphin morbillivirus (DMV) or phocine distemper virus (PDV) was isolated in affected individuals. While STX is notorious for its neurotoxicity, immunotoxic effects have also been described. This study investigated the role of STX in altering immune function, specifically T lymphocyte proliferation, in harbor seals (Phoca vitulina concolor) upon in-vitro exposure. In addition, the study also examined whether exposure to STX could alter the susceptibility of harbor seal immune cells to PDV infection upon in-vitro exposure. STX caused an increase in harbor seal lymphocyte proliferation at 10ppb and exposure to STX significantly increased the amount of virus present in lymphocytes. These results suggest that low levels of STX within the range of those reported in northeast U.S. seals may affect the likelihood of systemic PDV infection upon in-vivo exposure in susceptible seals. Given the concurrent increase in morbillivirus epizootics and HAB events in the last 25 years, the relationship between low level toxin exposure and host susceptibility to morbillivirus needs to be further explored.

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Research paper thumbnail of DEVELOPMENT OF A ONE-STEP DUPLEX RT-qPCR FOR THE QUANTIFICATION OF PHOCINE DISTEMPER VIRUS

Journal of wildlife diseases, Jan 3, 2015

Worldwide, stranded marine mammals and the network personnel who respond to marine mammal mortali... more Worldwide, stranded marine mammals and the network personnel who respond to marine mammal mortality have provided much of the information regarding marine morbillivirus infections. An assay to determine the amount of virus present in tissue samples would be useful to assist in routine surveying of animal health and for monitoring large-scale die-off events. False negatives from poor-quality samples prevent determination of the true extent of infection, while only small amounts of tissue samples or archived RNA may be available at the time of collection for future retrospective analysis. We developed a one-step duplex real-time reverse transcriptase-quantitative-PCR assay (RT-qPCR) based on Taqman probe technology to quantify phocine distemper virus (PDV) isolated from an outbreak in harbor (Phoca vitulina concolor) and gray seals (Halichoerus grypus) along the northeast US coast in 2006. The glyceraldehyde-3-phosphate-dehydrogenase (GAPDH) gene was selected to assess RNA quality. Th...

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Research paper thumbnail of Results of a community based disease monitoring program of marine mammals in arctic Canada

Oceans '04 MTS/IEEE Techno-Ocean '04 (IEEE Cat. No.04CH37600), 2004

It is the right of Canadian Inuit to hunt marine mammals for subsistence. Most of this food is co... more It is the right of Canadian Inuit to hunt marine mammals for subsistence. Most of this food is consumed raw, yet it under goes no formal government inspection or certification. Hunters also encounter sick or abnormal animals and they are becoming increasingly concerned about the wholesomeness of the food that they eat. They are also concerned about epizootics that may

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Research paper thumbnail of An insight into the epidemiology of dolphin morbillivirus worldwide

Veterinary Microbiology, 2001

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Research paper thumbnail of Cetacean Morbillivirus: Current Knowledge and Future Directions

Viruses, 2014

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Research paper thumbnail of Antibodies to selected pathogens in free-ranging terrestrial carnivores and marine mammals in Canada

Veterinary Record, 2004

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Research paper thumbnail of A Morbillivirus Antibody Survey of Atlantic Walrus, Narwhal and Beluga in Canada

Journal of Wildlife Diseases, 2000

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Research paper thumbnail of Serologic Survey of Brucella Spp. Antibodies in Some Marine Mammals of North America

Journal of Wildlife Diseases, 2001

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Research paper thumbnail of Bartonella Henselae in Captive and Hunter-Harvested Beluga (Delphinapterus Leucas)

Journal of Wildlife Diseases, 2008

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Research paper thumbnail of Use of a Slam Transfected Vero Cell Line to Isolate and Characterize Marine Mammal Morbilliviruses Using an Experimental Ferret Model

Journal of Wildlife Diseases, 2008

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Research paper thumbnail of Serologic Evidence of Influenza A Infection in Marine Mammals of Arctic Canada

Journal of Wildlife Diseases, 2001

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Research paper thumbnail of A Highly Divergent Picornavirus in a Marine Mammal

Journal of Virology, 2008

Nucleic acids from an unidentified virus from ringed seals (Phoca hispida) were amplified using s... more Nucleic acids from an unidentified virus from ringed seals (Phoca hispida) were amplified using sequence-independent PCR, subcloned, and then sequenced. The full genome of a novel RNA virus was derived, identifying the first sequence-confirmed picornavirus in a marine mammal. The phylogenetic position of the tentatively named seal picornavirus 1 (SePV-1) as an outlier to the grouping of parechoviruses was found consistently in alignable regions of the genome. A mean protein sequence identity of only 19.3 to 30.0% was found between the 3D polymerase gene sequence of SePV-1 and those of other picornaviruses. The predicted secondary structure of the short 506-base 5′-untranslated region showed some attributes of a type IVB internal ribosome entry site, and the polyprotein lacked an apparent L peptide, both properties associated with the Parechovirus genus. The presence of two SePV-1 2A genes and of the canonical sequence required for cotranslational cleavage resembled the genetic organ...

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Research paper thumbnail of Epizootiology of Morbillivirus Infection in Harp, Hooded, and Ringed Seals from the Canadian Arctic and Western Atlantic

Journal of Wildlife Diseases, 1997

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Research paper thumbnail of Novel Poxvirus Infection in Northern and Southern Sea Otters (Enhydra Lutris Kenyoni and Enhydra Lutris Neiris), Alaska and California, Usa

Journal of Wildlife Diseases, 2014

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Research paper thumbnail of Brucellosis in Ringed Seals and Harp Seals from Canada

Journal of Wildlife Diseases, 2000

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Research paper thumbnail of Serologic Survey for Potential Pathogens and Assessment of Disease Risk in Australian Fur Seals

Journal of Wildlife Diseases, 2011

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Research paper thumbnail of Epizootiology of Brucella Infection in Australian Fur Seals

Journal of Wildlife Diseases, 2011

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Research paper thumbnail of Sequential cold-sensitive mutations in Aspergillus fumigatus . II. Analysis by the parasexual cycle

Canadian Journal of Microbiology, 1981

From Aspergillus fumigatus I-21 (ATCC 32722), which grows at temperatures from 12 to 50 °C, three... more From Aspergillus fumigatus I-21 (ATCC 32722), which grows at temperatures from 12 to 50 °C, three multistep, independently derived, cold-sensitive mutants unable to grow at 37 °C or below (Cs-37) were obtained by sequential exposure to ethylmethane sulfonate (strain AT2) or N-methyl-N′-nitro-N-nitrosoguanidine (AT1 and AT3). These mutants and ON5, a five-step Cs-37 mutant, were marked by mutations affecting spore color and nutritional requirements and crossed in four combinations by classical parasexual means.The heterokaryons demonstrated partial complementation with respect to auxotrophic requirements (suboptimal growth on minimal medium) and cold sensitivity (growth at 37 °C but not at 25 °C). Most presumed diploids, formed by exposure of the heterokaryons to d-camphor vapors, showed complete complementation but were unstable, as demonstrated by variations in spore sizes and markedly different ratios of segregant classes derived from different clones.Analysis of the segregants of...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Streptococcus phocae in Marine Mammals of Northeastern Pacific and Arctic Canada: A Retrospective Analysis of 85 Postmortem Investigations

Journal of wildlife diseases, Jan 5, 2017

Streptococcus phocae is a pathogen of marine mammals, although its pathogenicity remains poorly u... more Streptococcus phocae is a pathogen of marine mammals, although its pathogenicity remains poorly understood. Recovery of this bacterium from asymptomatic carriers suggests that it is an opportunistic pathogen. We investigated the role of S. phocae in naturally occurring disease and its significance as a pathogen based on postmortem investigations. Between 2007 and 2012, 1,696 whole carcasses, tissue samples, or both were submitted from the northeastern Pacific and Arctic Canada for diagnostic testing. Streptococcus phocae was cultured from phocids (n=66), otariids (n=12), harbor porpoises (Phocoena phocoena; n=5), and sea otters (Enhydra lutris; n=2). Pathologic manifestations of S. phocae-associated disease included localized, as well as systemic, inflammatory lesions with common findings of suppurative bronchopneumonia (n=17) and bacteremia (n=27). Lung lesions were frequently culture-positive for S. phocae, suggesting commensal colonization of the oropharynx with subsequent opport...

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Research paper thumbnail of Demographic, ecological, and physiological responses of ringed seals to an abrupt decline in sea ice availability

PeerJ, 2017

To assess whether demographic declines of Arctic species at the southern limit of their range wil... more To assess whether demographic declines of Arctic species at the southern limit of their range will be gradual or punctuated, we compared large-scale environmental patterns including sea ice dynamics to ringed seal (Pusa hispida) reproduction, body condition, recruitment, and stress in Hudson Bay from 2003 to 2013. Aerial surveys suggested a gradual decline in seal density from 1995 to 2013, with the lowest density occurring in 2013. Body condition decreased and stress (cortisol) increased over time in relation to longer open water periods. The 2010 open water period in Hudson Bay coincided with extremes in large-scale atmospheric patterns (North Atlantic Oscillation, Arctic Oscillation, El Nino-Southern Oscillation) resulting in the earliest spring breakup and the latest ice formation on record. The warming event was coincident with high stress level, low ovulation rate, low pregnancy rate, few pups in the Inuit harvest, and observations of sick seals. Results provide evidence of ch...

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Research paper thumbnail of Saxitoxin increases phocine distemper virus replication upon in-vitro infection in harbor seal immune cells

Harmful Algae, 2016

Several marine mammal epizootics have been closely linked to infectious diseases, as well as to t... more Several marine mammal epizootics have been closely linked to infectious diseases, as well as to the biotoxins produced by harmful algal blooms (HABs). In two of three saxitoxin (STX) associated mortality events, dolphin morbillivirus (DMV) or phocine distemper virus (PDV) was isolated in affected individuals. While STX is notorious for its neurotoxicity, immunotoxic effects have also been described. This study investigated the role of STX in altering immune function, specifically T lymphocyte proliferation, in harbor seals (Phoca vitulina concolor) upon in-vitro exposure. In addition, the study also examined whether exposure to STX could alter the susceptibility of harbor seal immune cells to PDV infection upon in-vitro exposure. STX caused an increase in harbor seal lymphocyte proliferation at 10ppb and exposure to STX significantly increased the amount of virus present in lymphocytes. These results suggest that low levels of STX within the range of those reported in northeast U.S. seals may affect the likelihood of systemic PDV infection upon in-vivo exposure in susceptible seals. Given the concurrent increase in morbillivirus epizootics and HAB events in the last 25 years, the relationship between low level toxin exposure and host susceptibility to morbillivirus needs to be further explored.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of DEVELOPMENT OF A ONE-STEP DUPLEX RT-qPCR FOR THE QUANTIFICATION OF PHOCINE DISTEMPER VIRUS

Journal of wildlife diseases, Jan 3, 2015

Worldwide, stranded marine mammals and the network personnel who respond to marine mammal mortali... more Worldwide, stranded marine mammals and the network personnel who respond to marine mammal mortality have provided much of the information regarding marine morbillivirus infections. An assay to determine the amount of virus present in tissue samples would be useful to assist in routine surveying of animal health and for monitoring large-scale die-off events. False negatives from poor-quality samples prevent determination of the true extent of infection, while only small amounts of tissue samples or archived RNA may be available at the time of collection for future retrospective analysis. We developed a one-step duplex real-time reverse transcriptase-quantitative-PCR assay (RT-qPCR) based on Taqman probe technology to quantify phocine distemper virus (PDV) isolated from an outbreak in harbor (Phoca vitulina concolor) and gray seals (Halichoerus grypus) along the northeast US coast in 2006. The glyceraldehyde-3-phosphate-dehydrogenase (GAPDH) gene was selected to assess RNA quality. Th...

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Research paper thumbnail of Results of a community based disease monitoring program of marine mammals in arctic Canada

Oceans '04 MTS/IEEE Techno-Ocean '04 (IEEE Cat. No.04CH37600), 2004

It is the right of Canadian Inuit to hunt marine mammals for subsistence. Most of this food is co... more It is the right of Canadian Inuit to hunt marine mammals for subsistence. Most of this food is consumed raw, yet it under goes no formal government inspection or certification. Hunters also encounter sick or abnormal animals and they are becoming increasingly concerned about the wholesomeness of the food that they eat. They are also concerned about epizootics that may

Bookmarks Related papers MentionsView impact

Research paper thumbnail of An insight into the epidemiology of dolphin morbillivirus worldwide

Veterinary Microbiology, 2001

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Cetacean Morbillivirus: Current Knowledge and Future Directions

Viruses, 2014

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Antibodies to selected pathogens in free-ranging terrestrial carnivores and marine mammals in Canada

Veterinary Record, 2004

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A Morbillivirus Antibody Survey of Atlantic Walrus, Narwhal and Beluga in Canada

Journal of Wildlife Diseases, 2000

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Serologic Survey of Brucella Spp. Antibodies in Some Marine Mammals of North America

Journal of Wildlife Diseases, 2001

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Bartonella Henselae in Captive and Hunter-Harvested Beluga (Delphinapterus Leucas)

Journal of Wildlife Diseases, 2008

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Use of a Slam Transfected Vero Cell Line to Isolate and Characterize Marine Mammal Morbilliviruses Using an Experimental Ferret Model

Journal of Wildlife Diseases, 2008

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Serologic Evidence of Influenza A Infection in Marine Mammals of Arctic Canada

Journal of Wildlife Diseases, 2001

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A Highly Divergent Picornavirus in a Marine Mammal

Journal of Virology, 2008

Nucleic acids from an unidentified virus from ringed seals (Phoca hispida) were amplified using s... more Nucleic acids from an unidentified virus from ringed seals (Phoca hispida) were amplified using sequence-independent PCR, subcloned, and then sequenced. The full genome of a novel RNA virus was derived, identifying the first sequence-confirmed picornavirus in a marine mammal. The phylogenetic position of the tentatively named seal picornavirus 1 (SePV-1) as an outlier to the grouping of parechoviruses was found consistently in alignable regions of the genome. A mean protein sequence identity of only 19.3 to 30.0% was found between the 3D polymerase gene sequence of SePV-1 and those of other picornaviruses. The predicted secondary structure of the short 506-base 5′-untranslated region showed some attributes of a type IVB internal ribosome entry site, and the polyprotein lacked an apparent L peptide, both properties associated with the Parechovirus genus. The presence of two SePV-1 2A genes and of the canonical sequence required for cotranslational cleavage resembled the genetic organ...

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