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  • 1
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR á€" Recent investigations of the ocean's iron cycle have focused primarily on the response of phytoplankton to iron enrichment1. Bacteria, however, are important in the trophodynamics and elemental cycles of marine ecosystems2'3. With the exception of phototrophic ...
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  • 2
    Publication Date: 2022-05-25
    Description: Author Posting. © National Shellfisheries Association, 2007. This article is posted here by permission of National Shellfisheries Association for personal use, not for redistribution. The definitive version was published in Journal of Shellfish Research 26 (2007): 371-381, doi:10.2983/0730-8000(2007)26[371:EOQPUQ]2.0.CO;2.
    Description: The economically important marine bivalve mollusc, Mercenaria mercenaria, (commonly called a northern quahog or hard clam), has endured considerable mortalities caused by a thraustochytrid pathogen called Quahog Parasite X (QPX). Data on the percent prevalence of QPX infections were compiled from published reports along with our data to describe the epizootiology of QPX disease. QPX infections occurred in clams collected from both cultured beds and wild populations, but a higher percentage of QPX cases (76.5%) were from cultured clam beds. In addition, samples from cultured beds had a significantly higher prevalence (29.2 ± 27.2%) of QPX infections compared with samples from wild populations (9.6 ± 9.6%). The highest prevalence of QPX infections occurred in clams from samples with an intermediate size range (shell lengths 20–55 mm). QPX infections occurred in both male and female clams, but infection prevalence does not appear to be correlated with sex or sex ratios. The geographical range of QPX-related clam mortalities was Atlantic Canada to the Eastern Shore of Virginia, USA. Only marginally significant differences were detected between the prevalence of QPX at different locations. There were no latitudinal gradients in QPX prevalence or frequencies, suggesting local factors were important in determining its distribution. Although QPX infections occurred throughout the year, no seasonal trends in the prevalence or frequencies of QPX were discernable. This summary of information available on QPX disease highlights the need for more thorough data collection regarding factors believed to be associated with its presence and severity in hard clams.
    Description: This work was funded by a National Science Foundation Graduate Fellowship to M. Lyons, and partially funded by an Ecology of Infectious Disease Grant (EF 0429004) to R. S. and J. E. W. Surveys in Rhode Island were funded by the Rhode Island Aquaculture Initiative and the Rhode Island Department of Environmental Management, Fish and Wildlife.
    Keywords: Quahog Parasite X (QPX) ; Thraustochytrid ; Mercenaria mercenaria ; Clam ; Northern quahog
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 3
    Publication Date: 2022-05-25
    Description: Author Posting. © Inter-Research, 2008. This article is posted here by permission of Inter-Research for personal use, not for redistribution. The definitive version was published in Diseases of Aquatic Organisms 81 (2008): 219-229, doi:10.3354/dao01948.
    Description: Quahog Parasite Unknown (QPX) is the cause of mass mortality events of hard clams Mercenaria mercenaria from Virginia, USA, to New Brunswick, Canada. Aquaculture areas in Massachusetts, USA, have been particularly hard hit. The parasite has been shown to be a directly infective organism, but it is unclear whether it could exist or persist outside of its clam host. We used molecular methods to examine water, sediment, seaweeds, seagrass and various invertebrates for the presence of QPX. Sites in Virginia and Massachusetts were selected based upon the incidence of QPX-induced clam die-offs, and they were monitored seasonally. QPX was detectable in almost all of our different sample types from Massachusetts, indicating that the parasite was widely distributed in the environment. Significantly more samples from Massachusetts were positive than from Virginia, and there was a seasonal pattern to the types of samples positive from Massachusetts. The data suggest that, although it may be difficult to completely eradicate QPX from the environment, it may be possible to keep the incidence of disease under control through good plot husbandry and the removal of infected and dying clams.
    Description: This work is the result of research sponsored by NOAA National Sea Grant College Program Office, Department of Commerce, under Grant No. NA16RG2273, Woods Hole Oceanographic Institution Sea Grant Project No. R/B-168.
    Keywords: Quahog Parasite Unknown ; QPX ; Environmental detection ; Remediation
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 4
    Publication Date: 2022-05-25
    Description: Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of American Society of Limnology and Oceanography for personal use, not for redistribution. The definitive version was published in Limnology and Oceanography 50 (2005): 1983-1988, doi:10.4319/lo.2005.50.6.1983.
    Description: We evaluated marine aggregates as environmental reservoirs for a thraustochytrid pathogen, Quahog Parasite Unknown (QPX), of the northern quahog or hard clam, Mercenaria mercenaria. Positive results from in situ hybridization and denaturing gradient gel electrophoresis confirm the presence of QPX in marine aggregates collected from coastal embayments in Cape Cod, Massachusetts, where QPX outbreaks have occurred. In laboratory experiments, aggregates were observed and recorded by entering a quahog’s pallial cavity, thereby delivering embedded particles from the water column to its benthic bivalve host. The occurrence of pathogen-laden aggregates in coastal areas experiencing repeated disease outbreaks suggests a means for the spread and survival of pathogens between epidemics and provides a specific target for environmental monitoring of those pathogens.
    Description: This work was funded by an NSF grant as part of the joint NSF-NIH Ecology of Infectious Disease program, by the Woods Hole Oceanographic Institution (WHOI) Sea Grant Program, under a grant from the National Oceanic and Atmospheric Administration, U.S. Department of Commerce, and a National Science Foundation Graduate Fellowship to M. Lyons.
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
    Format: 511524 bytes
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  • 5
    Publication Date: 2022-05-26
    Description: Author Posting. © Inter-Research, 2006. This article is posted here by permission of Inter-Research for personal use, not for redistribution. The definitive version was published in Diseases of Aquatic Organisms 72 (2006): 45-52, doi:10.3354/dao072045.
    Description: Quahog Parasite Unknown (QPX) is a thraustochytrid pathogen responsible for catastrophic mortalities of the northern quahog (hard clam) Mercenaria mercenaria. A real-time quantitative polymerase chain reaction (qPCR) assay was developed to assist research efforts on QPX ecology and pathology. Sensitivity of the assay was evaluated with serial dilutions of QPX-cultured cells to determine the lowest concentration of DNA that remained detectable in both the presence and absence of extraneous environmental substances. QPX cells were quantified before DNA extraction to calibrate standard curves to cell counts. Based on our results, the qPCR assay is able to quantify QPX within the range of 1 to several thousand organisms per reaction. Specificity of the assay was assessed by testing 29 thraustochytrid-like protists isolated from suspension-feeding bivalves from China, Oregon, Maryland, and Virginia. Application of the assay was demonstrated with positive qPCR results from naturally contaminated environmental samples including marine aggregates (i.e. marine snow), clam pseudofeces, and inflammatory nodules from infected clams. This quantitative assay for QPX will provide a valuable tool for characterizing QPX parasite abundances in coastal environments and for improving clam disease diagnostics.
    Description: This research was funded in part by NSF-NIH Ecology of Infectious Disease Grant (No. 0429018) to R.S. and a grant to R.S. and S.B.R. from the County of Barnstable, Massachusetts.
    Keywords: Quahog Parasite Unknown ; QPX ; Thraustochytrids ; Mercenaria mercenaria ; Real-time PCR ; Histology ; Marine aggregates ; Pseudofeces ; Clams
    Repository Name: Woods Hole Open Access Server
    Type: Article
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