Abundance of thraustochytrid fungi in the Arabian Sea

Raghukumar, Seshagiri; Raghukumar, Chandralata; Rajendran, A.

doi:10.1016/0272-7714(90)90109-5

Cited by 18 publications

(17 citation statements)

References 5 publications

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“…Therefore, the involvement of thraustochytrid-C in POC is negligible. In a previous study (Raghukumar et al 1990), thraustochytrid abundance and POC concentration were not significantly correlated in the pelagic Arabian Sea water. The study area, Seto Inland Sea, receives a river discharge of, for example, 62 km 3 yr -1 in 1985 (Yanagi 1996).…”

Section: Correlation Between Decomposer Abundances and Environmental mentioning

confidence: 59%

“…Previous studies have determined the abundance of thraustochytrids over a wide range of habitats, including the water column, algae, particulate detritus and invertebrates (Raghukumar et al 1990, Riemann & Schaumann 1993, Frank et al 1994, Naganuma et al 1998, Kimura et al 1999. A rapid direct detection tech- ABSTRACT: Abundances of planktonic thraustochytrids and bacterioplankton were investigated in the Seto Inland Sea, Japan, with reference to concentrations of potential growth substrates such as dissolved organic carbon (DOC) and particulate organic carbon (POC) concentration and of phytoplankton (chlorophyll a concentration).…”

Section: Introductionmentioning

confidence: 99%

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Coupling of thraustochytrids and POM, and of bacterio- and phytoplankton in a semi-enclosed coastal area: implication for different substrate preference by the planktonic decomposers

Kimura¹,

Sato²,

Sugiyama³

et al. 2001

Aquat. Microb. Ecol.

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Section: Correlation Between Decomposer Abundances and Environmental mentioning

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Coupling of thraustochytrids and POM, and of bacterio- and phytoplankton in a semi-enclosed coastal area: implication for different substrate preference by the planktonic decomposers

Kimura¹,

Sato²,

Sugiyama³

et al. 2001

Aquat. Microb. Ecol.

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“…Thraustochytrids were found In the water column (Fig 2) at a population (Raghukumar et al 1990) and to 1.5 X 10' cells 1 ' SD, the thraustochytrid counts were correlated with in coastal North Sea water, counted as 'infectious the abundances of bacterioplankton and phytoplankentities' (Schneider 1977). These counts were based ton, thus indicat~ng a general relationship among them on cultivation, and thus the counts were predictably (Table 2; see next section).…”

Section: Abundance Of Thraustochytridsmentioning

confidence: 99%

“…Thraustochytrids are found in saline lakes as well as marine and estuarine waters. Although thraustochytrid thalli, sporangia and resting spores are noted as being epi/endobiotic and sessile (Karling 1981, Rheinheimer 1991, some have been found in the water column (Schneider 1977, Moss 1986, Raghukumar et al 1990). Recently, a rapid direct detection technique using the fluorogenic acriflavine dye was developed and used for the enumeration of particle-bound thraustochytrids (Raghukumar & Schaumann 1993).…”

Section: Introductionmentioning

confidence: 99%

Abundance of thraustochytrids in coastal plankton

Naganuma¹,

Takasugi²,

Kimura³

1998

Mar. Ecol. Prog. Ser.

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The abundance of thraustochytrids was investigated in and off the Seto Inland Sea, Japan. Thraustochytrid cells were stained with acriflavine and counted directly by epifluorescence rnicroscopy. Thraustochytrids were present in the water column at a density of 2.1 X 103 to 5.6 X 10' cells I-', with an overall average of 1.0 X 104 cells I-', which was about IO-' to 10-%of the bacterioplankton abundance. In contrast to the low abundance of thraustochytrids, their biovolume was estmated to compose a not negligible fraction of manne microbiota, correspond~ng to about 3 to 43'-X, of the bacterioplankton b~ovolume. Thus, it is suggested that thraustochytrids play an ecological role as alternative food sources for picoplankton feeders, as well as being actlve degraders and consumers in aquatic microbial food chains.

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“…the closest relatives to QPX) are ubiquitous yet taxonomically enigmatic. Thraustochytrids have been documented in coastal (Naganuma et al 1998), oceanic (Raghukumar et al 1990) and benthic (Santangelo et al 2000) habitats, living on both plant (Sharma et al 1994) and animal (Raghukumar 2002) substrates, but the number of DNA sequences available for comparison remains limited (Mo et al 2002). The suite of thraustochytridlike isolates used in our study represents the best available current resource for comparison to QPX-like organisms, and thereby demonstrates specificity of the qpxIRK primer set to the target parasite.…”

Section: Discussionmentioning

confidence: 90%

Development of a real time quantitative PCR assay for the hard clam pathogen Quahog Parasite Unknown (QPX)

Lyons

Smolowitz²,

Dungan³

et al. 2006

Dis. Aquat. Org.

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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.KEY WORDS: Quahog Parasite Unknown · QPX · Thraustochytrids · Mercenaria mercenaria · Real-time PCR · Histology · Marine aggregates · Pseudofeces · Clams Resale or republication not permitted without written consent of the publisherDis Aquat Org 72: [45][46][47][48][49][50][51][52] 2006 recorded (Dove et al. 2004). These large-scale mortality events in both cultured and wild clam beds have devastated parts of the hard clam shellfishing industry. QPX remains a primary concern for regulators because there are several clam-growing areas within the range of QPX (i.e. Canada to Virginia) that have not experienced clam mortalities due to QPX.QPX is broadly classified with the thraustochytrids (Maas et al. 1999, Ragan et al. 2000, Stokes et al. 2002, a group of elusive marine protists common in coastal environments (Raghukumar 2002). They are facultative parasites recently detected embedded within marine aggregates (i.e. marine snow) collected from clam-growing coastal waters affected by QPX outbreaks (Lyons et al. 2005). In the environment, marine aggregates are aspirated through the inhalant siphon of the clam during normal feeding processes, and are thought to facilitate entry of this microscopic pathogen into its benthic host. Marine aggregates have been identified as a possible target for environmental surveillance of QPX (Lyons et al. 2005). However, ecological disease research is hindered because there is no quantitative detection technique to enumerate the number of QPX parasites in environmental samples.The primary diagnostic method for QPX infections in clams is histological analysis (Howard et al. 2004). This procedure cannot be used for environmental samples such as seawater, sediment, macrophytes, or marine a...

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Abundance of thraustochytrid fungi in the Arabian Sea

Cited by 18 publications

References 5 publications

Coupling of thraustochytrids and POM, and of bacterio- and phytoplankton in a semi-enclosed coastal area: implication for different substrate preference by the planktonic decomposers

Coupling of thraustochytrids and POM, and of bacterio- and phytoplankton in a semi-enclosed coastal area: implication for different substrate preference by the planktonic decomposers

Abundance of thraustochytrids in coastal plankton

Development of a real time quantitative PCR assay for the hard clam pathogen Quahog Parasite Unknown (QPX)

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