| characterization of the small subunit ribosomal rna gene of the oyster parasite haplosporidium costale. | the small subunit ribosomal rna (ssu rrna) gene of the oyster parasite haplosporidium costale was characterized from spore dna by polymerase chain reaction (pcr) and molecular cloning. sequence analysis showed that identical clones were obtained from separate batches of spore samples. the gene is 1791 nucleotides in size. it has 84.5% sequence similarity to that of a related oyster parasite, haplosporidium nelsoni, 71.8% similarity to that of its oyster host, crassostrea virginica, and 75.4% sim ... | 1995 | 7670599 |
| acute osmotic tolerance of cultured cells of the oyster pathogen perkinsus marinus (apicomplexa:perkinsida). | cultured perkinsus marinus cells were exposed for 24 hr to salinities of 0, 3, 6, 9, 12 and 22 ppt at temperatures of 1, 5, 10, 15 and 28 degrees c in artificial seawater (asw) and to the same salinities at 28 degrees c in asw with the osmotic concentration adjusted with sucrose to the equivalent of 22 ppt. at 28 degrees c mortality increased as salinity decreased below 22 ppt. mortality was greater than 99% at 0 ppt and greater than 90% at 3 ppt. mortality was 70% at 6 ppt, 43% at 9 ppt and 20% ... | 1994 | 8529003 |
| in vitro interaction of perkinsus marinus merozoites with eastern and pacific oyster hemocytes. | this study compared hemocyte responses of eastern and pacific oysters to perkinsus marinus, in vitro. except for the percentage of hemocytes associated with p. marinus there was little or no significant difference between eastern and pacific oysters with regard to their hemocytic response to p. marinus. in phagocytosis assays, merozoites were bound to all hemocyte types but in unequal proportions, unlike zymosan which was found predominantly associated with granulocytes. the number of merozoites ... | 1995 | 8617400 |
| contribution of perkinsus marinus extracellular products in the infection of eastern oysters (crassostrea virginica). | | 1996 | 8931368 |
| in vitro activity of the limulus antimicrobial peptide tachyplesin i on marine bivalve pathogens | tachyplesin 1 is an antimicrobial peptide extracted from hemocytes of the japanese horseshoe crab tachypleus tridentatus. we studied the in vitro activity of tachyplesin i against bivalve pathogens: the oyster parasites bonamia ostreae, the intrahemocytic parasite of the flat oyster ostrea edulis and perkinsus marinus, the histozoic parasite of the eastern oyster crassostrea virginica, and the bacterium vibrio p1, pathogenic for the clam tapes philippinarum. viability of the protozoans was asses ... | 1997 | 9056468 |
| phylogenetic analysis of perkinsus based on actin gene sequences. | perkinsus species presently are classified within the phylum apicomplexa. this placement, however, is controversial. based upon morphological observations and phylogenetic analyses of the small subunit ribosomal rna gene, it has been suggested that perkinsus may be more closely related to dinoflagellates. to reevaluate the phylogenetic position of perkinsus, we obtained nucleotide sequence data for actin genes from perkinsus marinus and 2 dinoflagellates, prorocentrum minimum and amphidinium car ... | 1997 | 9194820 |
| acid phosphatase activity in perkinsus marinus, the protistan parasite of the american oyster, crassostrea virginica. | the effect of temperature (4, 12, 20, and 28 c) and osmolality (400, 570, and 840 mosm/kg) on extracellular acid phosphatase (ap) secretion in vitro, and ultrastructural localization of ap activity in the parasite were investigated. the extracellular ap secretion by perkinsus marinus was cell density dependent (p < 0.001). increasing culture temperatures resulted in increased p. marinus proliferation concomitant with ap secretion (p < 0.0001). ap secretion was similar in p. marinus cultured at 4 ... | 1997 | 9406785 |
| perkinsus marinus tissue distribution and seasonal variation in oysters crassostrea virginica from florida, virginia and new york. | perkinsus marinus infection intensity was measured in eastern oysters crassostrea virginica collected in october and december 1993, and march, may, and july 1994 from 3 u.s. sites: apalachicola bay (fl), chesapeake bay (va), and oyster bay (ny). gill, mantle, digestive gland, adductor muscle, hemolymph, and remaining tissue (including gonadal material and rectum) were dissected from 20 oysters from each site at each collection time. samples were separately diagnosed for p. marinus infections by ... | 1998 | 9789979 |
| species-specificity and sensitivity of a pcr-based assay for perkinsus marinus in the eastern oyster, crassostrea virginica: a comparison with the fluid thioglycollate assay. | we examined the species-specificity and sensitivity of a polymerase chain reaction (pcr)-based assay for perkinsus marinus and compared its overall performance with the fluid thioglycollate medium (ftm) assay on oyster (crassostrea virginica) hemolymph, mantle, and rectum samples. our results indicated that the pcr-based methodology is species-specific because perkinsus olseni, perkinsus atlanticus, and perkinsus spp. dnas were not amplified with the pcr primers developed for p. marinus diagnosi ... | 1998 | 9920320 |
| in vivo dynamics of the microparasite perkinsus marinus during progression and regression of infections in eastern oysters. | we used a total body parasite burden assay for the oyster pathogen perkinsus marinus to investigate quantitative changes in microparasite burdens and frequency distributions. heretofore, this type of study was limited mainly to macroparasites. the apparent in vivo growth pattern of p. marinus was characterized by a "lag" phase (< 10 cells/g wet weight [g wwt], a "log" phase (10-10,000 cells/g wwt), and a "stationary" phase (> 10,000 cells/g wwt). infections declined exponentially under condition ... | 1999 | 10219308 |
| characterization of two perkinsus spp. from the softshell clam, mya arenaria using the small subunit ribosomal rna gene. | sequence analysis and riboprinting of the small subunit ribosomal rna genes were used to characterize two morphologically different perkinsus species isolates from the gill (g117) and the hemolymph (h49) of the softshell clam, mya arenaria. sequence data of the polymerase chain reaction amplified ribosomal rna loci of g117 and h49 indicated that these genes are 1803 and 1806 base-pair long, respectively. a sequence similarity of > 98.9% was calculated among ribosomal rna sequences of the two iso ... | 1999 | 10461386 |
| perkinsus marinus extracellular protease modulates survival of vibrio vulnificus in eastern oyster (crassostrea virginica) hemocytes. | the in vitro effects of the perkinsus marinus serine protease on the intracellular survival of vibrio vulnificus in oyster hemocytes were examined by using a time-course gentamicin internalization assay. results showed that protease-treated hemocytes were initially slower to internalize v. vulnificus than untreated hemocytes. after 1 h, the elimination of v. vulnificus by treated hemocytes was significantly suppressed compared with hemocytes infected with invasive and noninvasive controls. our d ... | 1999 | 10473449 |
| analysis of the effects of perkinsus marinus proteases on plasma proteins of the eastern oyster (crassostrea virginica) and the pacific oyster (crassostrea gigas). | we employed two in vitro buffer systems to determine the potential pathogenic effects of perkinsus marinus serine proteases on the plasma proteins of the eastern oyster (crassostrea virginica) and the pacific oyster (crassostrea gigas). specifically, this study characterized the oyster plasma protein targets of p. marinus proteases. additionally, protease-specific inhibitory activity was revealed upon comparison of artificial (pbs) and endogenous (plasma-based) diluents employed during protease ... | 1999 | 10486230 |
| discrimination between two perkinsus spp. isolated from the softshell clam, mya arenaria, by sequence analysis of two internal transcribed spacer regions and the 5.8s ribosomal rna gene. | the internal transcribed spacer (its-1 and its-2) regions and the 5.8s ribosomal rna gene of 2 perkinsus spp. (g117 and h49) originating from the softshell clam, mya arenaria, of the chesapeake bay were cloned and sequenced to obtain evidence for their genetic divergence. a high level of heterogeneity in both regions, probably resulting from deletions, insertions, and base substitutions, was evident from alignments of the sequences of the 2 isolates with published sequences of other perkinsus sp ... | 1999 | 10581614 |
| use of micromanipulation and "feeder layers" to clone the oyster pathogen perkinsus marinus. | genetic and biochemical characterization of microbes often requires the use of clonal cultures. a method to clone the oyster parasite perkinsus marinus is described. individual cells are isolated via micromanipulation and maintained above an actively proliferating "feeder layer" of p. marinus on a 0.45-microm membrane. extracellular products released from the proliferating feeder layer can diffuse across the membrane and bathe the isolated cell, stimulating it to proliferate. the method is relat ... | 2000 | 10750845 |
| a quantitative competitive polymerase chain reaction assay for the oyster pathogen perkinsus marinus. | a quantitative competitive polymerase chain reaction (qcpcr) assay was developed for the oyster parasite perkinsus marinus. pcr primers for the rrna gene region of p. marinus amplified dna isolated from p. marinus but not from perkinsus atlanticus, crassostrea virginica, or the dinoflagellates peridinium sp., gymnodinium sp., or amphidinium sp. a mutagenic primer was used to create a competitor plasmid molecule identical to the p. marinus target dna sequence except for a 13-bp deletion. both p. ... | 2000 | 10958465 |
| characterization of the ribosomal rna locus of perkinsus atlanticus and development of a polymerase chain reaction-based diagnostic assay. | the rrna locus of perkinsus atlanticus from the clam ruditapes decussatus cultivated on the atlantic coast of spain was cloned and sequenced. sequences of the internal transcribed spacer (its) from the rrna locus were compared to sequences reported earlier for a p. atlanticus isolate from portugal and to those from other perkinsus species. the its i sequence of the spanish p. atlanticus isolate was identical to the portuguese p. atlanticus sequence and had 76.6% identity to the its1 of perkinsus ... | 2000 | 11128520 |
| the geographic distribution of population health and contaminant body burden in gulf of mexico oysters. | as part of noaa's national status and trends mussel watch program, oysters were sampled along the gulf of mexico coast each winter from 1986 to 1993 (the present analysis deals with 1986-1993 mussel watch data; the mussel watch project itself continues at this printing) and analyzed for trace metal, polynuclear aromatic hydrocarbons and pesticide body burden, plus a series of biological variables designed to assess population status and health. we identified contaminant and biological variables ... | 2001 | 11385588 |
| development of a multiplex pcr for the detection of haplosporidium nelsoni, haplosporidium costale and perkinsus marinus in the eastern oyster (crassostrea virginica, gmelin, 1971). | haplosporidium costale (sso), haplosporidium nelsoni (msx) and perkinsus marinus (dermo) have caused oyster mortality on the north american east coast since the 1950s. currently, the monitoring of oyster populations for these pathogens depends on histopathology for h. nelsoni, h. costale and the ray/mackin assay for p. marinus. in this study we describe the development and optimization of a multiplex polymerase chain reaction (mpcr) for the detection of h. nelsoni, h. costale and p. marinus. in ... | 2001 | 11851382 |
| serological affinities of the oyster pathogen perkinsus marinus (apicomplexa) with some dinoflagellates (dinophyceae). | the protozoan oyster pathogen perkinsus marinus is classified in the phylum apicomplexa, although molecular-genetic and ultrastructural evidence increasingly concur on its closer phylogenetic relationship with the dinoflagellates. to test for evidence of serological epitopes common to p. marinus and dinoflagellates, we probed 19 free-living and 8 parasitic dinoflagellate, or dinoflagellate-like, species for cross-reactivity with polyclonal antibodies to p. marinus. three of 19 free-living dinofl ... | 2002 | 11908893 |
| phospholipid biosynthesis in the oyster protozoan parasite, perkinsus marinus. | perkinsus marinus is a protozoan parasite that causes high mortality in its commercially and ecologically important host, the eastern oyster crassostrea virginica. in order to understand the host-parasite relationship in lipid metabolism, the ability of p. marinus to synthesize phospholipids from polar headgroup precursors was investigated. pulse/chase experiments were conducted using radiolabled serine, choline, ethanolamine and inositol. timecourse incubations revealed that in vitro cultured p ... | 2002 | 12034458 |
| protease inhibitors and haemagglutinins associated with resistance to the protozoan parasite, perkinsus marinus, in the pacific oyster, crassostrea gigas. | perkinsus marinus is a protozoan responsible for dramatic mortality in the eastern oyster, crassostrea virginica, but not in the pacific oyster, c. gigas. to understand the host-parasite relationship, we inoculated p. marinus trophozoites into the shell cavity of c. gigas and measured, over 2 months, (i) intensity of infection, (ii) protease inhibitory activities against p. marinus proteases and against bovine z-chymotrypsin, (iii) plasma haemagglutinin titre, (iv) plasma protein concentration, ... | 2002 | 12403320 |
| development of an in vitro clonal culture and characterization of the rrna gene cluster of perkinsus atlanticus, a protistan parasite of the clam tapes decussatus. | perkinsus atlanticus cultures were established either with trophozoites isolated from fresh gills, with hypnospores isolated from tissues incubated in fluid thioglycollate medium, or directly from infected hemocytes of carpet shell clams tapes decussatus from algarve (southern portugal), using a culture medium and conditions optimized for perkinsus marinus. perkinsus atlanticus isolates were cloned by limiting dilution, and their identity unequivocally established by pcr-based species-specific d ... | 2002 | 12425530 |
| comparison of in vitro-cultured and wild-type perkinsus marinus. iii. fecal elimination and its role in transmission. | perkinsus marinus, a pathogen of the eastern oyster crassostrea virginica, is transmitted directly among oysters. previous studies found viable p. marinus parasites in the feces and pseudofeces of oysters within hours of injection with parasites, suggesting that the parasite may be voided from live oysters and subsequently dispersed in the water column. the experiments described here were designed to quantify p. marinus shed in the feces and pseudofeces of experimentally infected oysters. the re ... | 2002 | 12465879 |
| continuous in vitro culture of the carpet shell clam tapes decussatus protozoan parasite perkinsus atlanticus. | continuous in vitro cultures of the clam tapes decussatus parasite perkinsus atlanticus were established from infected gill fragments, infected haemolymph and parasite hypnospores isolated from infected gill fragments following incubation in ray's fluid thioglycollate medium (rftm). no continuous cultures could be initiated from p. atlanticus zoospores. cultures initiated from hypnospores yielded the highest percentage of continuous cultures (100%, 6/6), followed by cultures initiated from gill ... | 2002 | 12553450 |
| the pmsod1 gene of the protistan parasite perkinsus marinus complements the sod2delta mutant of saccharomyces cerevisiae, and directs an iron superoxide dismutase to mitochondria. | the facultative intracellular oyster parasite, perkinsus marinus, taxonomically related to both dinoflagellates and apicomplexan parasites, possesses at least two distinct genes (pmsod1 and pmsod2) predicted to encode iron-containing superoxide dismutases (fe-sod). the present study demonstrates that pmsod1 complements a saccharomyces cerevisiae mutant lacking the mitochondrial manganese-containing sod (mn-sod), whereas pmsod2 complements an escherichia coli mutant lacking genes for cytosolic so ... | 2003 | 12554087 |
| comparison of in vitro-cultured and wild-type perkinsus marinus. ii. dosing methods and host response. | endoparasites must breach host barriers to establish infection and then must survive host internal defenses to cause disease. such barriers may frustrate attempts to experimentally transmit parasites by 'natural' methods. in addition, the host's condition may affect a study's outcome. the experiments reported here examined the effect of dosing method and host metabolic condition on measures of virulence for the oyster parasite perkinsus marinus. oysters, crassostrea virginica, were challenged wi ... | 2002 | 12465878 |
| gene organization and homology modeling of two iron superoxide dismutases of the early branching protist perkinsus marinus. | the facultative intracellular oyster parasite, perkinsus marinus, taxonomically related to both dinoflagellates and apicomplexans, possesses at least two distinct genes (pmsod1 and pmsod2) predicted to encode iron-containing superoxide dismutases (fesod). dna blots and sequence analysis suggest that both pmsod1 and pmsod2 are single copy and are unlinked. pmsod1 and pmsod2 are composed of five and six exons, respectively. all introns are delimited by canonical gt/ag boundaries, and have some fea ... | 2003 | 12727353 |
| host oyster tissue extracts modulate in vitro protease expression and cellular differentiation in the protozoan parasite, perkinsus marinus. | perkinsus marinus is responsible for a chronic disease (dermo) of the eastern oyster, crassostrea virginica. in order to simulate the in vivo environment more closely, a chemically defined medium (jl-odrp-3) was supplemented with tissue homogenate extracts or plasma from oysters possessing varying degrees of susceptibility to p. marinus infection. in media supplemented with extracts from highly susceptible oysters (c. virginica), p. marinus cells secreted elevated amounts of a set of low molecul ... | 2003 | 12741508 |
| superoxide dismutases from the oyster parasite perkinsus marinus: purification, biochemical characterization, and development of a plate microassay for activity. | we have isolated and biochemically characterized superoxide dismutase (sod) activity in cell extracts of clonally cultured perkinsus marinus, a facultative intracellular parasite of the eastern oyster, crassostrea virginica. in order to assess the sod activity throughout the purification, we developed and optimized a 96-well-plate microassay based on the inhibition of pyrogallol oxidation. the assay was also adapted to identify sod activity type (cu/zn-, mn-, or fesod), even in mixtures of more ... | 2003 | 12782041 |
| comparison of in vitro-cultured and wild-type perkinsus marinus. i. pathogen virulence. | perkinsus marinus is a highly contagious pathogen of the eastern oyster crassostrea virginica. until recently, transmission studies have employed wild-type parasites isolated directly from infected oysters. newly developed methods to propagate p. marinus in vitro have led to using cultured parasites for infection studies, but results suggest that cultured parasites are less virulent than wild-type parasites in this paper, we report results of experiments designed to quantify differences between ... | 2002 | 12465877 |
| cdna cloning and characterization of two iron superoxide dismutases from the oyster parasite perkinsus marinus. | | 2002 | 12165391 |
| apoptosis in the pathogenesis of infectious diseases of the eastern oyster crassostrea virginica. | apoptosis, or programmed cell death, has been reported as being pivotal in infectious diseases of different organisms. the effects of apoptosis on the progression and transmission of the protistan parasites perkinsus marinus and haplosporidium nelsoni in the eastern oyster crassostrea virginica were studied. oysters were diagnosed for their respective infections by standard methods, and apoptosis was detected using in situ hybridization to detect dna fragments by end labeling on paraffin section ... | 2003 | 14598992 |
| protease activity in the plasma of american oysters, crassostrea virginica, experimentally infected with the protozoan parasite perkinsus marinus. | perkinsus marinus is responsible for disease and mortality of the american oyster, crassostrea virginica. to investigate the interactions between p. marinus and oyster hemocytes, protease activity was measured in plasma of oysters collected 4 hr, 24 hr, 4 days, and 2 mo after experimental infection with p. marinus. a significant increase in protease activity was observed in oyster plasma 4 hr after injection with p. marinus, followed by a sharp decrease within 24 hr. gelatin-impregnated gel elec ... | 2003 | 14627141 |
| effects of plasma from bivalve mollusk species on the in vitro proliferation of the protistan parasite perkinsus marinus. | the in vitro culture of the eastern oyster parasite perkinsus marinus has provided a unique opportunity to examine its susceptibility to putative recognition and effector defense mechanisms operative in refractory bivalve species. in this study, we report the effect of supplementing the culture medium with plasma from: (1) uninfected to heavily infected eastern oysters; (2) oyster species considered to be disease-resistant; and (3) bivalve mollusk species that are naturally exposed to the parasi ... | 2002 | 11857456 |
| de novo arachidonic acid synthesis in perkinsus marinus, a protozoan parasite of the eastern oyster crassostrea virginica. | the capability of synthesizing fatty acids de novo in the meront stage of the oyster protozoan parasite, perkinsus marinus, was investigated employing stable-isotope-labeled precursors (1,2 13c-acetate and palmitic-d(31) acid). fatty acid methyl esters derived from 1,2 13c-acetate and palmitic-d(31) acid were analyzed using gas chromatography/mass spectrometry and gas chromatography/flame ionization detection. results revealed that in vitro cultured p. marinus meronts utilized 13c-acetate to syn ... | 2002 | 11814570 |
| cellular responses and disease expression in oysters (crassostrea virginica) exposed to suspended field contaminated sediments. | exposure of oysters to water soluble fractions derived from field-contaminated sediments (fcs) containing predominantly lower molecular weight organic aromatic compounds, has been previously demonstrated to enhance pre-existing infections caused by the protozoan parasite, perkinsus marinus (dermo), and the prevalence of experimentally induced infections. to further explore the role of pollution on the onset and progression of disease, effects of suspended fcs from an estuarine creek in virginia, ... | 2002 | 11767253 |
| perkinsus marinus, a protozoan parasite of the eastern oyster (crassostrea virginica): effects of temperature on the uptake and metabolism of fluorescent lipid analogs and lipase activities. | the effects of temperature on the uptake and metabolism of fluorescent labeled palmitic acid (flc16) and phosphatidylcholine (flpc) and lipase activities in the oyster protozoan parasite, perkinsus marinus, meront stage were tested at 10, 18, and 28 degrees c. temperature significantly affected not only the uptake, assimilation, and metabolism of both flc16 and flpc in p. marinus, but also its triacylglycerol (tag) lipase activities. the incorporation of both flc16 and flpc increased with temper ... | 2003 | 14969689 |
| the protistan parasite perkinsus marinus is resistant to selected reactive oxygen species. | the parasite perkinsus marinus has devastated natural and farmed oyster populations along the atlantic and gulf coasts of north america. when viable p. marinus trophozoites are engulfed by oyster hemocytes, the typical accumulation of reactive oxygen species (ros) normally associated with phagocyte activity is not observed. one hypothesis to explain this is that the parasite rapidly removes ros. a manifestation of efficient ros removal should be a high level of resistance to exogenous ros. we in ... | 2003 | 14990317 |
| development of a pcr-elisa assay for diagnosis of perkinsus marinus and perkinsus atlanticus infections in bivalve molluscs. | perkinsus atlanticus and p. marinus have been associated with mass mortality of bivalve molluscs. perkinsus infections are routinely diagnosed by histology or the fluid thioglycollate medium (ftm) assay. in this study, we describe the development of a pcr-enzyme-linked immunosorbent assay (elisa) for amplification and rapid detection of perkinsus species. the pcr reactions were selected to either amplify an igs sequence region shared by currently accepted perkinsus species or to simultaneously a ... | 2004 | 15051117 |
| proteolytic activity of cultured pseudoperkinsus tapetis extracellular products. | several pathogenic protozoan release proteases are necessary for host invasion and initiation of infection. we have identified proteolytic activities in extracellular proteins secreted by the clam parasite pseudoperkinsus tapetis (mesomycetozoa) in vitro. the protein concentration of the p. tapetis extracellular products (ecp) increased only during the first week of culture. the appearance of new proteins of 10 and 157 kda at the second week sample and of 12 kda at the third week sample was show ... | 2001 | 11544090 |
| ultrastructural characteristics of the in vitro cell cycle of the protozoan pathogen of oysters, perkinsus marinus. | ultrastructural characteristics of vegetative and zoosporangial stages of cultured perkinsus marinus, a pathogen of the eastern oyster, crassostrea virginica, were examined by transmission electron microscopy. an axenic cell culture was propagated from infected chesapeake bay oyster hemolymph. different stages of the in vitro cell cycle, including schizonts and different size trophonts, were examined. trophonts had spherical nuclei with wide perinuclear spaces, mitochondria with tubular cristae, ... | 2001 | 11411844 |
| fine structure of clonally propagated in vitro life stages of a perkinsus sp. isolated from the baltic clam macoma balthica. | we established monoclonal in vitro cultures of a perkinsus sp. isolated from the baltic clam macoma balthica and compared morphological features of various life stages by light and transmission electron microscopy to those of the currently accepted perkinsus species: perkinsus marinus, perkinsus olseni, perkinsus atlanticus, and perkinsus qugwadi. except that trophozoites were slightly larger than those of p. marinus, and that they underwent zoosporulation in culture, observation of our isolate ... | 2001 | 11249192 |
| flow cytometric analysis of lectin binding to in vitro-cultured perkinsus marinus surface carbohydrates. | parasite surface glycoconjugates are frequently involved in cellular recognition and colonization of the host. this study reports on the identification of perkinsus marinus surface carbohydrates by flow cytometric analyses of fluorescein isothiocyanate-conjugated lectin binding. lectin-binding specificity was confirmed by sugar inhibition and kolmogorov-smirnov statistics. clear, measurable fluorescence peaks were discriminated, and no parasite autofluorescence was observed. parasites (gtla-5 an ... | 2004 | 15270084 |
| lipid class composition of the protozoan perkinsus marinus, an oyster parasite, and its metabolism of a fluorescent phosphatidylcholine analog. | perkinsus marinus is one of two important protozoan parasites of the eastern oyster, crassostrea virginica. the other is haplosporidium nelsoni. lipids extracted from 7-d-old in vitro cultured p. marinus meronts, incubated with fluorescent-labeled phosphatidylcholine (fl pc) and nonincubated p. marinus meronts, were analyzed by a high-performance liquid chromatography (hplc) system equipped with a diol phase column, in combination with thin-layer chromatography coupled with a flame-ionization de ... | 2000 | 11202001 |
| uptake and interconversion of fluorescent lipid analogs in the protozoan parasite, perkinsus marinus, of the oyster, crassostrea virginica. | uptake, distribution, and interconversion of fluorescent lipid analogs (phosphatidylcholine, pc; cholesteryl ester, che; phosphatidylethanolamine, pe; palmitic acid, c16; sphingomyelin, sm) by the two life stages, meront and prezoosporangium, of the oyster protozoan parasite, perkinsus marinus, were investigated. class composition of these two life stages and lipid contents in meront cells were also examined. both meronts and prezoosporangia incorporated and modified fluorescent lipids from the ... | 2000 | 11038307 |
| gene organization and expression of the divalent cation transporter nramp in the protistan parasite perkinsus marinus. | trophozoites of the protistan parasite perkinsus marinus reside and proliferate inside phagosomelike structures of hemocytes from the host, the eastern oyster crassostrea virginica. in a murine model, it has been proposed that the outcome of intracellular parasite-host interactions is determined, at least in part, by the activity of the host's divalent cation transporter natural resistance-associated macrophage protein 1 (nramp1). although nucleotide sequences from members of the nramp family in ... | 2004 | 15562599 |
| analysis of extracellular proteins of two perkinsus spp. isolated from the softshell clam mya arenaria in vitro. | biochemical characterization of the extracellular proteins (ecp) of two softshell clam perkinsus spp. cloned isolates, perkinsus chesapeaki isolate g-117 and perkinsus marinus h-49, was performed and compared to that of the oyster-derived p. marinus isolate p-1. g-117 and h-49 demonstrated distinct differences in enzyme activities; however, all three isolates shared common bands. substrate-impregnated gels showed h-49 to possess proteolytic activities while g-117 did not. inhibition studies reve ... | 2000 | 11026671 |
| whole animal and gill tissue oxygen uptake in the eastern oyster, crassostrea virginica: effects of hypoxia, hypercapnia, air exposure, and infection with the protozoan parasite perkinsus marinus(1). | the eastern oyster, crassostrea virginica, lives in shallow coastal waters and experiences many different environmental extremes including hypoxia, hypercapnia and air exposure and many oysters are infected with the protozoan parasite perkinsus marinus. the effects of these conditions on oyster metabolism, as measured by oxygen uptake, were investigated. mild hypercapnia had no effect on the ability of oysters to regulate oxygen uptake in hypoxic water, as measured by the b2 coefficient of oxyge ... | 2000 | 10713278 |
| assessment of the cell viability of cultured perkinsus marinus (perkinsea), a parasitic protozoan of the eastern oyster, crassostrea virginica, using sybrgreen-propidium iodide double staining and flow cytometry. | a flow cytometry (fcm) assay using sybrgreen and propidium iodide double staining was tested to assess viability and morphological parameters of perkinsus marinus under different cold- and heat-shock treatments and at different growth phases. p. marinus meront cells, cultivated at 28 degrees c, were incubated in triplicate for 30 min at -80 degrees c, -20 degrees c, 5 degrees c, and 20 degrees c for cold-shock treatments and at 32 degrees c, 36 degrees c, 40 degrees c, 44 degrees c, 48 degrees c ... | 2005 | 16313441 |
| nucleotide sequence variability in the nontranscribed spacer of the rrna locus in the oyster parasite perkinsus marinus. | we examined the sequence variability of the nontranscribed spacer (nts) and internal-transcribed spacer (its1 and its2) domains of the rrna locus of perkinsus marinus from maryland, florida, and louisiana. the sequence of p. marinus dna including the 5s rrna, nts, small subunit (ssu) rrna, itsi, and its2 regions confirmed their contiguity in the rrna locus and revealed differences at 28 positions with the ssu rrna sequences published earlier. the 307-bp polymerase chain reaction (pcr)-amplified ... | 1999 | 10461944 |
| real-time pcr investigation of parasite ecology: in situ determination of oyster parasite perkinsus marinus transmission dynamics in lower chesapeake bay. | perkinsus marinus is a severe pathogen of the oyster crassostrea virginica on the east coast of the united states. transmission dynamics of this parasite were investigated in situ for 2 consecutive years (may through october) at 2 lower chesapeake bay sites. compared to previous studies where seasonal infection patterns in oysters were measured, this study also provided parasite water column abundance data measured using real-time pcr. as previously observed, salinity and temperature modulated p ... | 2006 | 16476183 |
| 'total evidence' refutes the inclusion of perkinsus species in the phylum apicomplexa. | the phylogenetic affinities of the oyster pathogen perkinsus marinus were investigated with morphology, 18s-like rdna data and actin sequence data. morphological investigations revealed that perkinsus species do not have a conoid and that other criteria which have been used to place them in the apicomplexa are general to alveolates. when considered separately, 18s-like rdna and actin data sets each support a closer affinity for perkinsus marinus with the dinoflagellates. however, each of these s ... | 1997 | 10190172 |
| recombinant expression of the antimicrobial peptide polyphemusin and its activity against the protozoan oyster pathogen perkinsus marinus. | polyphemusin is a broad-spectrum antimicrobial peptide isolated from hemocytes of the north american horseshoe crab limulus polyphemus. to date the polyphemusin used for scientific analyses has been purified from the natural materials or obtained by chemical synthesis. we report here the recombinant expression in escherichia coli, and subsequent purification, of a polyphemusin analogue (rlim1). to prevent toxicity of the antimicrobial peptide in the highly susceptible e. coli host, we used a car ... | 1997 | 9284563 |
| small subunit ribosomal rna gene sequence of the oyster parasite perkinsus marinus. | the small subunit rrna gene of the oyster pathogen perkinsus marinus was characterized from cells of infected oyster hemolymph by polymerase chain reaction and molecular cloning. the gene, 1,793 nucleotides in size, has 77.2% sequence similarity to that of its host, the eastern oyster crassostrea virginica. the sequence was confirmed using recently available in vitro cultures of p. marinus. dna from pure p. marinus culture was amplified with specific primers synthesized according to the sequence ... | 1993 | 8193669 |
| inhibition of in vitro replication of the oyster parasite perkinsus marinus by the natural iron chelators transferrin, lactoferrin, and desferrioxamine. | the mammalian iron-binding proteins transferrin and lactoferrin, the bactericidal peptide lactoferricin b, and the bacterial siderophore desferrioxamine were tested for their ability to inhibit the in vitro replication of the oyster parasite perkinsus marinus. all three chelators were effective in reducing the parasite proliferation in a dose-dependent manner. lactoferricin b, a peptide of lactoferrin that exhibits bactericidal properties unrelated to iron chelation, had no inhibitory activity o ... | 1994 | 7883057 |
| a semiquantitative pcr assay for assessing perkinsus marinus infections in the eastern oyster, crassostrea virginica. | a 3.2-kb fragment of perkinsus marinus dna was cloned and sequenced. a noncoding domain was identified and targeted for the development of a semiquantitative polymerase chain reaction (pcr) assay for the presence of p. marinus in eastern oyster tissues. the assay involves extracting total dna from oyster hemolymph and using 1 microgram of that dna as template in a stringent pcr amplification with oligonucleotide primers that are specific for the p. marinus 3.2-kb fragment. with this assay, we ca ... | 1995 | 7623200 |
| suppression of chemiluminescence of eastern oyster (crassostrea virginica) hemocytes by the protozoan parasite perkinsus marinus. | experiments were conducted to determine the ability of the protistan parasite, perkinsus marinus, to inhibit chemiluminescence of hemocytes from the eastern oyster, crassostrea virginica. luminol-enhanced chemiluminescence (cl) was used to measure the production of reactive oxygen intermediates (roi) generated by oyster hemocytes using zymosan as a stimulant. to determine whether p. marinus suppresses roi evoked from zymosan-stimulated hemocytes, live or heat killed p. marinus in filtered estuar ... | 1995 | 7556800 |
| effect of fetal bovine serum glycoproteins on the in vitro proliferation of the oyster parasite perkinsus marinus: development of a fully defined medium. | the oyster parasite perkinsus marinus replicates in our medium consisting of dulbecco modified eagle's medium: ham's f12 nutrient mixture (1:1) supplemented with 1-5% fetal bovine serum, with a doubling time of 24 hours during the exponential phase of the culture. fetal bovine serum concentrations above 5% dramatically reduced parasite proliferation in a dose-dependent manner. we tested the individual effects of the three major protein components of fetal bovine serum (fetuin, transferrin and al ... | 1995 | 7496389 |
| fine structure of perkinsus atlanticus n. sp. (apicomplexa, perkinsea) parasite of the clam ruditapes decussatus from portugal. | a new apicomplexan species, perkinsus atlanticus, is described from gill filaments of the clam ruditapes decussatus (bivalvia) from portugal, where it causes great mortality. the zoospores differ from those of other species of perkinsus in size and shape, dimensions, insertion of the 2 flagella, and in the identity of the host. on the other hand, the life cycle stages showed some ultrastructural differences compared with perkinsus marinus, the only species previously studied in detail. when the ... | 1989 | 2760774 |
| role of nitric oxide in the defenses of crassostrea virginica to experimental infection with the protozoan parasite perkinsus marinus. | we investigated the role of nitric oxide (no) in the responses of the eastern oyster, crassostrea virginica, to the protozoan parasite perkinsus marinus, causative agent of dermo disease. p. marinus induced a slight but significant increase in no production by oyster hemocytes in vitro, comparable to the increase induced by the immune stimulants phorbol myristrate acetate (pma) and lipopolysaccharide (lps). p. marinus also activated the no response in oysters in vivo, as shown by induction of a ... | 2007 | 17368535 |
| influence of water allocation and freshwater inflow on oyster production: a hydrodynamic-oyster population model for galveston bay, texas, usa. | a hydrodynamic-oyster population model was developed to assess the effect of changes in freshwater inflow on oyster populations in galveston bay, texas, usa. the population model includes the effects of environmental conditions, predators, and the oyster parasite, perkinsus marinus, on oyster populations. the hydrodynamic model includes the effects of wind stress, river runoff, tides, and oceanic exchange on the circulation of the bay. simulations were run for low, mean, and high freshwater infl ... | 2003 | 12447579 |
| detection of minchinia sp., in rock oysters saccostrea cuccullata (born, 1778) using dna probes. | haplosporidian parasites infect various invertebrate hosts including some commercially important shellfish. haplosporidium nelsoni (along with perkinsus marinus) has severely affected eastern oyster production on the eastern seaboard of the united states and flat oyster production in europe has been severely impacted by bonamia ostreae. these parasites are also often present at a very low prevalence and there are a variety of morphologically similar species that can be difficult to differentiate ... | 2008 | 17709114 |
| multiple protein phylogenies show that oxyrrhis marina and perkinsus marinus are early branches of the dinoflagellate lineage. | oxyrrhis marina and perkinsus marinus are two alveolate species of key taxonomic position with respect to the divergence of apicomplexans and dinoflagellates. new sequences from oxyrrhis, perkinsus and a number of dinoflagellates were added to datasets of small-subunit (ssu) rrna, actin, alpha-tubulin and beta-tubulin sequences, as well as to a combined dataset of all three protein-coding genes, and phylogenetic trees were inferred. the parasitic perkinsus marinus branches at the base of the din ... | 2003 | 12656195 |
| lipid class and fatty acid composition of the protozoan parasite of oysters, perkinsus marinus cultivated in two different media. | the meront stage of the oyster protozoan parasite, perkinsus marinus, cultivated in two media with different fatty acid profiles was analyzed for its fatty acid and lipid class composition. the composition of fatty acids in the prezoosporangium stage of the parasite as well as that of the host oyster were investigated. although the lipid class composition of meronts was dominated by phospholipids and triacylglycerol, there was no triaclgycerol detected in either culture medium. despite the diffe ... | 2001 | 11411839 |
| heat shock protein (hsp70) expression and thermal tolerance in sublethally heat-shocked eastern oysters crassostrea virginica infected with the parasite perkinsus marinus. | to investigate whether sublethal heat shock protects perkinsus marinus (dermo)-infected oysters crassostrea virginica from lethal heat stress, and the effects of p. marinus infection on sublethal heat shock response, oysters were first experimentally challenged with p. marinus. then, when infections in oysters progressed to moderate levels (parasite burden = 10(4) to 10(5) cells g(-1) wet tissue weight), oysters were treated with a sublethal heat shock at 40 degrees c for 1 h (heat shock + dermo ... | 2007 | 17803111 |
| real-time pcr for detection and quantification of the protistan parasite perkinsus marinus in environmental waters. | the protistan parasite perkinsus marinus is a severe pathogen of the oyster crassostrea virginica along the east coast of the united states. very few data have been collected, however, on the abundance of the parasite in environmental waters, limiting our understanding of p. marinus transmission dynamics. real-time pcr assays with sybrgreen i as a label for detection were developed in this study for quantification of p. marinus in environmental waters with p. marinus species-specific primers and ... | 2004 | 15528525 |
| monoclonal antibody analysis of perkinsus marinus extracellular products. | the protozoan oyster parasite perkinsus marinus releases a complex set of extracellular products (ecp) during in vitro culture. these products have been previously implicated in parasite virulence, and their expression can be altered by medium supplementation with oyster tissue homogenate. little is known regarding ecp function, regulation, or mechanism of storage and release. perkinsus marinus ecp were purified from a protein-free medium and used to produce a panel of five monoclonal antibodies ... | 2004 | 15710438 |
| potential novel epitopes in the extracellular products of oyster homogenate-supplemented perkinsus marinus cells are not detected by subtractive immunization. | the extracellular products (ecps) of the oyster parasite perkinsus marinus have been posed to contain virulence factors, including serine proteases. supplementation of p. marinus cultures with oyster homogenates enhances infectivity and changes the ecp composition. therefore, subtractive immunization was used to attempt creation of antibodies to proteins unique to ecps produced following parasite exposure to oyster homogenates. while control mice remained competent to respond to an unrelated ant ... | 2005 | 16108568 |
| effects of triclosan on growth, viability and fatty acid synthesis of the oyster protozoan parasite perkinsus marinus. | perkinsus marinus, a protozoan parasite of the eastern oyster crassostrea virginica, has severely impacted oyster populations from the mid-atlantic region to the gulf of mexico coast of north america for more than 30 yr. although a chemotherapeutic treatment to reduce or eliminate p. marinus from infected oysters would be useful for research and hatchery operations, an effective and practical drug treatment does not currently exist. in this study, the antimicrobial drug triclosan 5-chloro-2-(2,4 ... | 2005 | 16408837 |
| determination of the effects of temperature on viability, metabolic activity and proliferation of two perkinsus species, and its significance to understanding seasonal cycles of perkinsosis. | the range of water temperatures in which perkinsus species can survive and proliferate remains ill-defined, particularly at lower temperatures. the in vitro viability, metabolic activity, and proliferation of 3 isolates each of p. marinus and p. olseni trophozoites at 28 degrees c, and at 15 and 4 degrees c, after transfer from 28 degrees c, were compared. both species showed declines in metabolic activity and proliferation from 28 degrees c to 15 degrees c. at 4 degrees c, both species had viab ... | 2008 | 18248687 |
| parasite survey of the eastern oyster crassostrea virginica in coastal lagoons of the southern gulf of mexico. | a parasitological study of the eastern oyster crassostrea virginica from 11 coastal lagoons in the southern gulf of mexico in dry and rainy seasons between late 1999 and early 2001 revealed the presence of 36 bacterial, 2 protozoan (nematopsis prytherchi and perkinsus marinus), and 4 helminth species (urastoma cyprinae, proctoeces maculatus, a bucephalus sp., and a tylocephalum sp.). the prevalence and mean abundances for the protozoa and helminths varied widely between locations but were genera ... | 2007 | 18333483 |
| experimental cross-infections by perkinsus marinus and p. chesapeaki in three sympatric species of chesapeake bay oysters and clams. | in controlled laboratory transmission experiments, uniform doses of axenic in vitro isolate cultures of perkinsus marinus from a crassostrea virginica oyster, and of independent p. chesapeaki isolates from chesapeake bay mya arenaria and macoma balthica clams, were used to reciprocally challenge perkinsus sp.-free c. virginica, m. arenaria, and m. balthica experimental hosts. following mantle cavity inoculations, all 3 experimental hosts acquired high incidences (30 to 100%) of infections by eac ... | 2007 | 17718167 |
| the humoral response to in vitro generated parasite antigens is enhanced by the removal of a defined media component prior to immunization. | concentrated culture supernatants containing the extracellular products (ecp) of the protozoan oyster parasite perkinsus marinus were used to immunize mice. this preparation, produced by ultrafiltration, was found to be both poorly immunogenic and toxic to experimental animals. the possibility that these effects were due to toxic parasite products and/or medium constituents was examined. co-administration of this material with highly immunogenic oyster hemolymph caused a substantive suppression ... | 2003 | 12957397 |
| systematic evaluation of factors controlling perkinsus marinus transmission dynamics in lower chesapeake bay. | the transmission of perkinsus marinus in eastern oysters crassostrea virginica in relation to water temperature, host oyster mortality, and water-column abundance of anti-p. marinus antibody-labeled cells was systematically examined for 20 mo at a site in the lower york river, virginia, usa. uninfected sentinel oysters were naturally exposed to the parasite at 2 wk intervals throughout the course of the study to determine the periodicity and rates of parasite transmission. the timing and magnitu ... | 2003 | 14524504 |
| assessment of the northern distribution range of selected perkinsus species in eastern oysters (crassostrea virginica) and hard clams (mercenaria mercenaria) with the use of pcr-based detection assays. | perkinsus species are protistan parasites of molluscs. in chesapeake bay, perkinsus marinus, perkinsus chesapeaki, and perkinsus andrewsi are sympatric, infecting oysters and clams. although p. marinus is a pathogen for crassostrea virginica, it remains unknown whether p. andrewsi and p. chesapeaki are equally pathogenic. perkinsus species have been reported in c. virginica as far north as maine, sometimes associated with high prevalence, but low mortality. thus, we hypothesized that, in additio ... | 2008 | 18564742 |
| a galectin of unique domain organization from hemocytes of the eastern oyster (crassostrea virginica) is a receptor for the protistan parasite perkinsus marinus. | invertebrates display effective innate immune responses for defense against microbial infection. however, the protozoan parasite perkinsus marinus causes dermo disease in the eastern oyster crassostrea virginica and is responsible for catastrophic damage to shellfisheries and the estuarine environment in north america. the infection mechanisms remain unclear, but it is likely that, while filter feeding, the healthy oysters ingest p. marinus trophozoites released to the water column by the infect ... | 2007 | 17709523 |
| effects of salinity, heavy metals and pesticides on health and physiology of oysters in the caloosahatchee estuary, florida. | the caloosahatchee estuary has been exhibiting signs of impaired ecological health due to the extensive hydrological alteration, agricultural land use, and increasing watershed development. this project investigated the responses of the american oyster, crassostrea virginica at five locations in the caloosahatchee river in relation to salinity changes, levels of heavy metals, pesticides, and pcbs in the water as well as in the oyster tissue. individual heavy metal and organochlorine pesticide co ... | 2008 | 18686029 |
| arachidonic acid synthetic pathways of the oyster protozoan parasite, perkinsus marinus: evidence for usage of a delta-8 pathway. | the meront stage of the oyster protozoan parasite, perkinsus marinus, is capable of synthesizing saturated and unsaturated fatty acids including the essential fatty acid, arachidonic acid [20:4(n-6)]. eukaryotes employ either delta-6 (delta-6) or delta-8 (delta-8) desaturase pathway or both to synthesize arachidonic acid. to elucidate the arachidonic acid synthetic pathways in p. marinus, meronts were incubated with deuterium-labeled precursors [18:1(n-9)-d6, 18:2(n-6)-d4, 18:3(n-3)-d4, and 20:3 ... | 2004 | 14668011 |
| supplementation of perkinsus marinus cultures with host plasma or tissue homogenate enhances their infectivity. | the protozoan oyster parasite perkinsus marinus can be cultured in vitro in a variety of media; however, this has been associated with a rapid attenuation of infectivity. supplementation of defined media with products of p. marinus-susceptible (crassostrea virginica) and -tolerant (crassostrea gigas, crassostrea ariakensis) oysters alters proliferation and protease expression profiles and induces differentiation into morphological forms typically seen in vivo. it was not known if attenuation cou ... | 2004 | 14711671 |
| molecular epizootiology of perkinsus marinus and p. chesapeaki infections among wild oysters and clams in chesapeake bay, usa. | perkinsus marinus and p. chesapeaki host ranges among wild chesapeake bay, usa, region bivalves were examined by surveying crassostrea virginica oysters and members of several sympatric clam species from 11 locations. perkinsus genus- and species-specific pcr assays were performed on dna samples from 731 molluscs, and species-specific in situ hybridization assays were performed on a selected subset of histological samples whose pcr results indicated dual or atypical perkinsus sp. infections. pcr ... | 2008 | 19244976 |
| proteins related to green algal striated fiber assemblin are present in stramenopiles and alveolates. | in green algae, striated fiber assemblin (sfa) is the major protein of the striated microtubule-associated fibers that are structural elements in the flagellar basal apparatus. using basic local alignment search tool (blast) searches of recently established databases, sfa-like sequences were detected in the genomes not only of green algal species but also of a range of other protists. these included species in two alveolate subgroups, the ciliates (tetrahymena thermophila, paramecium tetraurelia ... | 2009 | 19333716 |
| isolation and characterization of serine protease gene(s) from perkinsus marinus. | this study reports the first serine protease gene(s) isolated from perkinsus marinus. using universal primers, a 518 bp subtilisin-like serine protease gene fragment was amplified from p. marinus genomic dna and used as a probe to screen a lambda-phage p. marinus genomic library; 2 different lambda-phage clones hybridized to the digoxigenin(dig)-labeled subtilisin-like gene fragment. following subcloning and sequencing of the larger dna fragment, a 1254 bp open reading frame was identified and l ... | 2003 | 14735929 |
| serine protease inhibitor cvsi-1 potential role in the eastern oyster host defense against the protozoan parasite perkinsus marinus. | the serine protease inhibitor cvsi-1, purified from plasma of eastern oysters, inhibited the proliferation of the protozoan parasite perkinsus marinus in vitro. in situ hybridization located cvsi-1 gene expression in basophil cells of the digestive tubules and cvsi-1 expression measured by real-time quantitative reverse transcriptase polymerase chain reaction was several hundred folds greater in digestive glands than in other organs examined or circulating hemocytes. cvsi-1 gene expression was a ... | 2010 | 19720077 |
| flow cytometry as a tool to quantify oyster defence mechanisms. | the fast growing oyster aquaculture industry is greatly hindered by perkinsus marinus and haplosporidium nelsoni which can kill up to 80% of the production. the relationship between parasites and oyster defence mechanisms is unclear. two defence mechanisms of the eastern oyster (crassostrea virginica) were quantified at the single cell level utilising flow cytometry. phagocytosis was measured using fluorescent beads. respiratory burst activity was quantified as the h2o2-specific increase in dich ... | 2004 | 15123295 |
| application of a multiplex pcr for the detection of protozoan pathogens of the eastern oyster crassostrea virginica in field samples. | populations of eastern oysters crassostrea virginica along the east coast of north america have repeatedly experienced epizootic mass mortality due to infections by protozoan parasites, and molecular diagnostic methodologies are fast becoming more widely available for the diagnosis of protozoan diseases of oysters. in this study we applied a modified version of an existing multiplex polymerase chain reaction (pcr) for detection of the eastern oyster parasites haplosporidium nelsoni, h. costale a ... | 2004 | 15212297 |
| the alveolate perkinsus marinus: biological insights from est gene discovery. | perkinsus marinus, a protozoan parasite of the eastern oyster crassostrea virginica, has devastated natural and farmed oyster populations along the atlantic and gulf coasts of the united states. it is classified as a member of the perkinsozoa, a recently established phylum considered close to the ancestor of ciliates, dinoflagellates, and apicomplexans, and a key taxon for understanding unique adaptations (e.g. parasitism) within the alveolata. despite intense parasite pressure, no disease-resis ... | 2010 | 20374649 |
| perkinsus marinus in crassostrea gigas in the gulf of california. | to determine the agent responsible for the massive mortalities of the pacific oyster crassostrea gigas in northwest mexico, 30 oysters were sampled after a severe mortality event in 2006 along the sonoran coast. histological analyses revealed the presence of a protozoan and ray's fluid thioglycollate medium (rftm) assays showed the presence of perkinsus sp., identified as p. marinus from the dna sequence of the internal transcribed spacer (its) of the ribosomal rna (rrna) gene complex. pcr analy ... | 2010 | 20481094 |
| extensive frameshift at all agg and ccc codons in the mitochondrial cytochrome c oxidase subunit 1 gene of perkinsus marinus (alveolata; dinoflagellata). | diverse mitochondrial (mt) genetic systems have evolved independently of the more uniform nuclear system and often employ modified genetic codes. the organization and genetic system of dinoflagellate mt genomes are particularly unusual and remain an evolutionary enigma. we determined the sequence of full-length cytochrome c oxidase subunit 1 (cox1) mrna of the earliest diverging dinoflagellate perkinsus and show that this gene resides in the mt genome. apparently, this mrna is not translated in ... | 2010 | 20507907 |
| multiple polymorphic sites at the its and atan loci in cultured isolates of perkinsus marinus. | sequence analysis of genomic dna from the protozoan parasite perkinsus marinus at two loci revealed genetic polymorphisms within and among different cultured isolates. genomic dna from 12 perkinsus marinus isolates was amplified at the internal transcribed spacer region and at an anonymous locus previously identified to contain polymorphisms by restriction fragment length polymorphism analysis. fourteen polymorphic nucleotide positions were identified at the internal transcribed spacer region; e ... | 2004 | 15218700 |
| introns, alternative splicing, spliced leader trans-splicing and differential expression of pcna and cyclin in perkinsus marinus. | to gain understanding on the structure and regulation of growth-related genes of the parasitic alveolateperkinsus marinus, we analyzed genes encoding proliferating cell nuclear antigen (pcna) and cyclins (cyclin). comparison of the full-length cdnas with the corresponding genomic sequences revealedtrans-splicing of the mrnas of these genes with a conserved 21-22 nt spliced leader. over 10 copies ofpcnawere detected, with identical gene structures and similar nucleotide (nt) sequences (88-99%), e ... | 2011 | 20650682 |
| phylogenetic analyses of the dinoflagellate noctiluca scintillans based on beta-tubulin and hsp90 genes. | the noctilucid dinoflagellate noctiluca scintillans is an unarmed heterotrophic protist that inhabits the world's oceans and is sometimes responsible for harmful red tides. the phylogenetic position of the noctilucids has been widely disputed because of two alternative views based on morphological characters and phylogenetic analyses using ssu rdna. specifically, noctilucids are either placed in a basal position within the dinoflagellates or they are seen as evolutionarily recent derivations des ... | 2008 | 17900881 |
| upregulation in response to infection and antibacterial activity of oyster histone h4. | several histones and histone-derived peptides have been shown to have antimicrobial activity and a potential role in innate immune defenses. a histone h4 sequence was identified in a subtractive suppression library containing genes upregulated in american cupped oysters, crassostrea virginica, in response to challenge with the protozoan parasite perkinsus marinus. oyster histone h4 protein levels significantly increased in hemocyte lysates and cell free hemolymph of oysters experimentally challe ... | 2010 | 20883794 |
| discovery of genes expressed in response to perkinsus marinus challenge in eastern (crassostrea virginica) and pacific (c. gigas) oysters. | the protozoan pathogen perkinsus marinus is the causative agent of dermo, a lethal disease of the eastern oyster crassostrea virginica, but not the pacific oyster crassostrea gigas. to understand the response of these two oysters to parasite exposure, a suppression subtractive hybridization (ssh) method was employed to characterize genes up-regulated during parasite challenge in both hemocytes and gills. the number of differentially expressed gene sequences obtained was 107 for c. virginica and ... | 2004 | 15302413 |
| polymorphism in a serine protease inhibitor gene and its association with disease resistance in the eastern oyster (crassostrea virginica gmelin). | serine protease inhibitors (spis) are a superfamily of structurally related but functionally diverse proteins found in almost all organisms ranging from viruses to humans. some of them play important roles in host defense. a recently identified spi from the eastern oyster (crassostrea virginica), cvsi-1, has been shown to inhibit the proliferation of the dermo pathogen perkinsus marinus in vitro, although direct evidence linking it to disease resistance is lacking. in this study, we identified p ... | 2011 | 21215804 |
| a novel slow-tight binding serine protease inhibitor from eastern oyster (crassostrea virginica) plasma inhibits perkinsin, the major extracellular protease of the oyster protozoan parasite perkinsus marinus. | a serine protease inhibitor was purified from plasma of the eastern oyster, crassostrea virginica. the inhibitor is a 7609.6 da protein consisting of 71 amino acids with 12 cysteine residues that are postulated to form 6 intra-chain disulfide bridges. sequencing of the cloned cdna identified an open reading frame encoding a polypeptide of 90 amino acids, with the 19 n-terminal amino acids forming a signal peptide. no sequence similarity with known proteins was found in sequence databases. the pr ... | 2006 | 16872855 |
| identification of two spliced leader rna transcripts from perkinsus marinus. | spliced leader (sl) variants are present in a number of mrnas from perkinsus marinus. three different sls of 22 nucleotides (nt) in length were previously reported, with a consensus sequence of (dccguagccauyuuggcucaag). a truncated 21 nt sl, with an (a) at nt-1 and a (u) deletion at nt-13, has also been reported. here, we report an additional 21 nt sl variant with (g) at nt-1. using cdna analysis, a full-length sl rna transcript was identified for both 21 nt sls (sl2[a] and sl2[g]). this transcr ... | 2011 | 21435079 |
| efl gtpase in cryptomonads and the distribution of efl and ef-1alpha in chromalveolates. | efl (ef-like protein) is a member of the gtpase superfamily that includes several translation factors. because it has only been found in a few eukaryotic lineages and its presence correlates with the absence of the related core translation factor ef-1alpha, its distribution is hypothesized to be the result of lateral gene transfer and replacement of ef-1alpha. in one supergroup of eukaryotes, the chromalveolates, two major lineages were found to contain efl (dinoflagellates and haptophytes), whi ... | 2006 | 16904374 |
| copper exposure affects hemocyte apoptosis and perkinsus marinus infection in eastern oysters crassostrea virginica (gmelin). | dermo disease in the eastern oyster (crassostrea virginica) is caused by an intracellular protistan parasite perkinsus marinus. the progression and outcome of this disease is determined by a complex interplay between the host's immunity and parasite's escape mechanisms, both of which can be influenced by environmental pollutants including heavy metals such as copper (cu). the goal of the present study was to determine the effects of cu on the levels of apoptosis (which can serve as an important ... | 2011 | 21658453 |
| viability, infectivity and fatty acid synthetic activity of perkinsus marinus meront cells incubated in estuarine and artificial seawater. | we investigated the viability and fatty acid synthetic activity of in vitro cultured perkinsus marinus (dermo) in lipid-free medium and estuarine water, and the infectivity of p. marinus maintained in artificial seawater (asw). viability and fatty acid synthetic activity in 7 d old p. marinus meronts maintained in lipid-free medium and estuarine water were tested. the infectivity of meronts incubated in asw was examined by first incubating p. marinus meronts in asw for 2, 3 or 7 d, and then inoc ... | 2006 | 16956060 |