Dataset Information

Molecular characterization of a novel gammaretrovirus in killer whales (Orcinus orca).

ABSTRACT: There are currently no published data documenting the presence of retroviruses in cetaceans, though the occurrences of cancers and immunodeficiency states suggest the potential. We examined tissues from adult killer whales and detected a novel gammaretrovirus by degenerate PCR. Reverse transcription-PCR also demonstrated tissue and serum expression of retroviral mRNA. The full-length sequence of the provirus was obtained by PCR, and a TaqMan-based copy number assay did not demonstrate evidence of productive infection. PCR on blood samples from 11 healthy captive killer whales and tissues from 3 free-ranging animals detected the proviral DNA in all tissues examined from all animals. A survey of multiple cetacean species by PCR for gag, pol, and env sequences showed homologs of this virus in the DNA of eight species of delphinids, pygmy and dwarf sperm whales, and harbor porpoises, but not in beluga or fin whales. Analysis of the bottlenose dolphin genome revealed two full-length proviral sequences with 97.4% and 96.9% nucleotide identity to the killer whale gammaretrovirus. The results of single-cell PCR on killer whale sperm and Southern blotting are also consistent with the conclusion that the provirus is endogenous. We suggest that this gammaretrovirus entered the delphinoid ancestor's genome before the divergence of modern dolphins or that an exogenous variant existed following divergence that was ultimately endogenized. However, the transcriptional activity demonstrated in tissues and the nearly intact viral genome suggest a more recent integration into the killer whale genome, favoring the latter hypothesis. The proposed name for this retrovirus is killer whale endogenous retrovirus.

SUBMITTER: Lamere SA

PROVIDER: S-EPMC2786842 | biostudies-literature | 2009 Dec

REPOSITORIES: biostudies-literature

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Publications

Molecular characterization of a novel gammaretrovirus in killer whales (Orcinus orca).

Lamere Sarah A SA St Leger Judy A JA Schrenzel Mark D MD Anthony Simon J SJ Rideout Bruce A BA Salomon Daniel R DR

Journal of virology 20091007 24

There are currently no published data documenting the presence of retroviruses in cetaceans, though the occurrences of cancers and immunodeficiency states suggest the potential. We examined tissues from adult killer whales and detected a novel gammaretrovirus by degenerate PCR. Reverse transcription-PCR also demonstrated tissue and serum expression of retroviral mRNA. The full-length sequence of the provirus was obtained by PCR, and a TaqMan-based copy number assay did not demonstrate evidence o ...[more]

PMID: 19812152

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Project description:Local adaption through ecological niche specialization can lead to genetic structure between and within populations. In the Northeast Pacific, killer whales (Orcinus orca) of the same population have uniform specialized diets that are non-overlapping with other sympatric, genetically divergent, and socially isolated killer whale ecotypes. However, killer whales in Iceland show intrapopulation variation of isotopic niches and observed movement patterns: some individuals appear to specialize on herring and follow it year-round while others feed upon herring only seasonally or opportunistically. We investigated genetic differentiation among Icelandic killer whales with different isotopic signatures and observed movement patterns. This information is key for management and conservation purposes but also for better understanding how niche specialization drives genetic differentiation. Photo-identified individuals (N = 61) were genotyped for 22 microsatellites and a 611 bp portion of the mitochondrial DNA (mtDNA) control region. Photo-identification of individuals allowed linkage of genetic data to existing data on individual isotopic niche, observed movement patterns, and social associations. Population subdivision into three genetic units was supported by a discriminant analysis of principal components (DAPC). Genetic clustering corresponded to the distribution of isotopic signatures, mtDNA haplotypes, and observed movement patterns, but genetic units were not socially segregated. Genetic differentiation was weak (F ST < 0.1), suggesting ongoing gene flow or recent separation of the genetic units. Our results show that killer whales in Iceland are not as genetically differentiated, ecologically discrete, or socially isolated as the Northeast Pacific prey-specialized killer whales. If any process of ecological divergence and niche specialization is taking place among killer whales in Iceland, it is likely at a very early stage and has not led to the patterns observed in the Northeast Pacific.

Project description:Over the past five decades, marine mammal interactions with fisheries have become a major human-wildlife conflict globally. The emergence of longline fishing is concomitant with the development of depredation-type interactions i.e., marine mammals feeding on fish caught on hooks. The killer whale (Orcinus orca) is one of the species most involved in depredation on longline fisheries. The issue was first reported in high latitudes but, with increasing expansion of this fishing method, other fisheries have begun to experience interactions. The present study investigated killer whale interactions with two geographically isolated blue-eye trevalla (Hyperoglyphe antarctica) fisheries operating in temperate waters off Amsterdam/St. Paul Islands (Indian Ocean) and south-eastern Australia. These two fisheries differ in the fishing technique used (vertical vs. demersal longlines), effort, catch, fleet size and fishing area size. Using 7-year (2010-16) long fishing and observation datasets, this study estimated the levels of killer whale interactions and examined the influence of spatio-temporal and operational variables on the probability of vessels to experience interactions. Killer whales interactions occurred during 58.4% and 21.2% of all fishing days, and over 94% and 47.4% of the fishing area for both fisheries, respectively. In south-eastern Australia, the probability of occurrence of killer whale interactions during fishing days varied seasonally with a decrease in spring, increased with the daily fishing effort and decreased with the distance travelled by the vessel between fishing days. In Amsterdam/St. Paul, this probability was only influenced by latitude, with an increase in the southern part of the area. Together, these findings document two previously unreported cases of high killer whale depredation, and provide insights on ways to avoid the issue. The study also emphasizes the need to further examine the local characteristics of fisheries and the ecology of local depredating killer whale populations in as important drivers of depredation.

Dataset Information

Molecular characterization of a novel gammaretrovirus in killer whales (Orcinus orca).

Publications

Molecular characterization of a novel gammaretrovirus in killer whales (Orcinus orca).

Similar Datasets

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