Feeding by the newly described mixotrophic dinoflagellate Paragymnodinium shiwhaense: feeding mechanism, prey species, and effect of prey concentration.

To investigate the feeding by the newly described mixotrophic dinoflagellate Paragymnodinium shiwhaense (GenBank accession number=AM408889), we explored the feeding process and the kinds of prey species that P. shiwhaense is able to feed on using several different types of microscopes, including a transmission electron microscope and high-resolution video-microscopy. In addition, we measured the growth and ingestion rates of P. shiwhaense on its optimal algal prey Amphidinium carterae as a function of prey concentration. We also measured these parameters for edible prey at a single concentration at which the growth and ingestion rates of P. shiwhaense on A. carterae were saturated. Paragymnodinium shiwhaense feed on algal prey using a peduncle after anchoring the prey by a tow filament. Among the algal prey offered, P. shiwhaense ingested small algal species that had equivalent spherical diameters (ESDs) < or =11 microm (e.g. the prymnesiophyte Isochrysis galbana, the cryptophytes Teleaulax sp. and Rhodomonas salina, the raphidophyte Heterosigma akashiwo, and the dinoflagellates Heterocapsa rotundata and A. carterae). However, it did not feed on larger algal species that had ESDs > or =12 microm (e.g. the dinoflagellates Prorocentrum minimum, Heterocapsa triquetra, Scrippsiella trochoidea, Alexandrium tamarense, Prorocentrum micans, Gymnodinium catenatum, Akashiwo sanguinea, and Lingulodinium polyedrum) or the small diatom Skeletonema costatum. The specific growth rates for P. shiwhaense feeding upon A. carterae increased rapidly with increasing mean prey concentration before saturating at concentrations of ca. 350 ng C/ml (5,000 cells/ml). The maximum specific growth rate (i.e. mixotrophic growth) of P. shiwhaense on A. carterae was 1.097/d at 20 degrees C under a 14:10 h light-dark cycle of 20 microE/m(2)/s, while its growth rate (i.e. phototrophic growth) under the same light conditions without added prey was -0.224/d. The maximum ingestion and clearance rates of P. shiwhaense on A. carterae were 0.38 ng C/grazer/d (5.4 cells/grazer/d) and 0.7 microl/grazer/h, respectively. The calculated grazing coefficients for P. shiwhaense on co-occurring Amphidinium spp. was up to 0.07/h (i.e. 6.7% of the population of Amphidinium spp. was removed by P. shiwhaense populations in 1 h). The results of the present study suggest that P. shiwhaense can have a considerable grazing impact on algal populations.

Localization of perialgal vacuoles beneath the host cell surface is not a prerequisite phenomenon for protection from the host's lysosomal fusion in the ciliate Paramecium bursaria.

In a ciliate Paramecium bursaria cell, each symbiotic 3-4-mum-diameter Chlorella cell is enclosed within a perialgal vacuole membrane. It localizes near trichocysts beneath the host cell surface. Gomori's staining of this surface shows that it is an acid phosphatase activity-negative area to 5-10mum depth. Trichocysts were removed by treatment with 1mg/ml lysozyme to elucidate whether algal protection from the host lysosomal fusion is controlled by localization of the perialgal vacuole membrane to the acid phosphatase activity-negative area or by the capability of the perialgal vacuole membrane to give protection from lysosomal fusion. The trichocyst-free cell reduced the acid phosphatase activity-negative area to less than 3mum depth at the dorsal surface. However, even though a part of the algal cell had been exposed in the acid phosphatase activity-positive area, the algae were able to attach beneath the host surface and to protect it from lysosomal fusion. Results of this study show that the perialgal vacuole membrane can give protection from host lysosomal fusion, and that the membrane does not require trichocysts for intracellular localization.

Loop-mediated isothermal amplification method for rapid detection of the toxic dinoflagellate Alexandrium, which causes algal blooms and poisoning of shellfish.

The marine dinoflagellate genus Alexandrium includes a number of species that produce potent neurotoxins responsible for paralytic shellfish poisoning, which in humans may cause muscular paralysis, neurological symptoms and, in extreme cases, death. Because of the genetic diversity of different genera and species, molecular tools may help to detect the presence of target microorganisms in marine field samples. Here we employed a loop-mediated isothermal amplification (LAMP) method for the rapid and simple detection of toxic Alexandrium species. A set of four primers were designed based upon the conserved region of the 5.8S rRNA gene of members of the genus Alexandrium. Using this detection system, toxic Alexandrium genes were amplified and visualized as a ladder-like pattern of bands on agarose gels under isothermal condition within 60 min. The LAMP amplicons were also directly visualized by eye in the reaction tube by the addition of SYBR Green I. This LAMP assay was 10-fold more sensitive than a conventional PCR method with a detection limit of 5 cells per tube when targeting DNA from Alexandrium minutum. The LAMP assay reported here indicates the potential usefulness of the technique as a valuable simple, rapid alternative procedure for the detection of target toxic Alexandrium species during coastal water monitoring.

Molecular phylogeny of a potentially parasitic dinoflagellate isolated from the solitary radiolarian, Thalassicolla nucleata.

Thalassicolla nucleata, a solitary radiolarian, has been described as being parasitized by two dinoflagellates, Solenodinium (Syndiniales) and Caryotoma (Blastodiniales). Several T. nucleata were stripped of their extracapsular material and allowed to regenerate their rhizopodial structures without symbionts. Within a week, two were observed to disintegrate, leaving behind non-pigmented swimming dinoflagellate cells. Identical full-length ribosomal sequences were recovered from both samples. Upon alignment and phylogenetic analysis, it was determined that these putative parasite sequences were distinct from Scrippsiella nutricula (the dinoflagellate symbiont of the host), and also from all other dinoflagellate parasites sequenced to date.

Chlamydomonas pitschmannii Ettl, a little known species from thermoacidic environments.

Three Chlamydomonas strains were isolated from the soils of a hot spring located in the Campi Flegrei Caldera (Naples, Italy). Ecophysiological, morpho-cytological and molecular features were used to characterize these isolates and to compare them with chlamydomonax acidophila strains from algal culture collections. The strains were collected from three points of the volcanic site, differing in their physico-chemical conditions. Among the examined Chlamydomonas strains, only the isolates from Campi Flegrei could grow optimally at pH values < or =3.0. These isolates also showed a high tolerance to desiccation and high temperatures, not evidenced by the other Chlamydomonas strains included in the study. 18S rDNA phylogeny indicates that the isolates from Campi Flegrei are closely related to Chlamydomonas pitschmannii and two strains isolated in Canada and Europe, that have been designated as Chlamydomonas acidophila. A Chlamydomonas acidophila strain isolated from the type locality in Japan is less closely related according to its molecular phylogeny, and can also be discerned by light and electron microscopy. Moreover, vegetative cells and sporangia of Chlamydomonas acidophila from Japan showed a median trilaminar structure not observed in the other strains. Our results show that Chlamydomonas pitschmannii could represent a hitherto unknown extremophilic Chlamydomonas species.

Trilosporoides platessae gen. et sp. n. (Myxozoa: Multivalvulida) in the plaice Pleuronectes platessa (Teleostei: Pleuronectidae) from Denmark.

A new myxosporean species, Trilosporoides platessae gen. et sp. n. (Multivalvulida), is described from the gallbladder of the plaice Pleuronectes platessa L. (Pleuronectidae) from Denmark. The myxospore of T. platessae is conical in side view, with a 24 microm long, pointed posterior projection. In apical view, the myxospore (diameter 9.4 microm) is round, trilobed and with three spherical polar capsules arranged peripherally, equidistant and opening peripherally through protruding tips. The polar capsules are of different sizes, one often larger than the others (diameter 3.3 microm vs. 2.5 microm). Apart from the long posterior projection, the myxospore of T. platessae differs from those of the three known species of Trilospora Noble, 1959 and from all genera within the order Multivalvulida Shulman, 1959 in the arrangement of the polar capsules. Trilosporoides platessae may temporarily be placed in the vicinity of the Trilosporidae.

Febre amarela, malária e protozoologia

Após introdução sobre a formação de Adolpho Lutz e sua capacitação como cientista, analisa alguns trechos de relatórios do Instituto Bacteriológico de 1893 a 1908; o parecer de Adolpho Lutz sobre um soro proposto para o tratamento da febre amarela; o relatório sobre sua missão em Montevidéu para verificar a provável 'descoberta' do Dr. Sanarelli relativa ao micróbio da febre amarela; os trabalhos sobre a febre amarela em São Paulo e sobre o mosquito como seu agente de propagação; a descoberta da malária silvestre; as instruções para profilaxia do impaludismo; e, finalmente, as suas 'Reminiscências da febre amarela no Estado de São Paulo', publicadas em 1930, quando Adolpho Lutz já era pesquisador do Instituto Oswaldo Cruz havia mais de 20 anos.

Adolpho Lutz: obra completa / Adolpho Lutz: complete works

Após introduçäo sobre a formaçäo de Adolpho Lutz e sua capacitaçäo como cientista, analisa alguns trechos de relatórios do Instituto Bacteriológico de 1893 a 1908; o parecer de Adolpho Lutz sobre um soro proposto para o tratamento da febre amarela; o relatório sobre sua missäo em Montevidéu para verificar a provável "descoberta" do Dr. Sanarelli relativa ao micróbio da febre amarela; os trabalhos sobre a febre amarela em Säo Paulo e sobre o mosquito como seu agente de propagaçäo; a descoberta da malária silvestre; as instruções para profilaxia do impaludismo; e, finalmente, as suas "Reminiscências da febre amarela no Estado de Säo Paulo", publicadas em 1930, quando Adolpho Lutz já era pesquisador do Instituto Oswaldo Cruz havia mais de 20 anos. (AU)

Use of ELISA to identify Protoceratium reticulatum as a source of yessotoxin in Norway.

Picked cells of Protoceratium reticulatum collected from five locations in Norway were shown by ELISA analysis to contain yessotoxins (YTXs). The production of yessotoxin (YTX) was verified by culturing followed by LC-MS analysis of one of the Norwegian isolates. This is the first report of the biogenic origin of YTXs in Norway. The sensitivity of the ELISA method made it possible to quantitate YTXs in algal cultures, net-hauls, and in single cells of P. reticulatum. The cells picked from cultures and net-hauls contained 18-79 pg YTXs per cell. Dilution series and analyses of cells from non-YTX-producing algal species demonstrated the presence of only minimal matrix effects on the ELISA, probably attributable to the presence of salts. The sensitivity of this method makes it possible to search for other possible producers of YTXs, and might also make it possible to follow the YTXs through the food chain. This method allows, for the first time, measurement of the variability in toxin content within a population of dinoflagellate cells--rather than just the average amount of toxin per cell.

Molecular players of homologous recombination in protozoan parasites: implications for generating antigenic variation.

A major impediment to vaccine development against infections caused by protozoan parasites such as Plasmodium falciparum and Trypanosoma is the extraordinary ability of these parasites to rapidly change their surface molecules, a phenomenon known as antigenic variation. A prominent determinant of antigenic variation in these organisms is associated with rearrangements of genes, especially those known as var in P. falciparum and vsg in Trypanosoma. However, mechanisms underlying generation of anitgenic diversities among these protozoan parasites are poorly understood. The hypothesis that links all the different sections in this review is that antigenic variations in the protozoan parasites is coupled with genetic rearrangements, which occur during the course of DNA break repair. Here, we provide comprehensive and up-to-date information on Rad51 in these organisms, an eukaryotic homologue of bacterial RecA, and homologous recombination mechanisms. In trypanosomes both Rad51-dependent and -independent mechanisms have been suggested to play roles in antigenic variation. Finally, we speculate on how might similar DNA repair mechanisms contribute to genetic rearrangement associated with antigenic variation in the apicomplexan Plasmodium parasites, an immune evasion strategy.

Actin and ubiquitin protein sequences support a cercozoan/foraminiferan ancestry for the plasmodiophorid plant pathogens.

The plasmodiophorids are a group of eukaryotic intracellular parasites that cause disease in a variety of economically significant crops. Plasmodiophorids have traditionally been considered fungi but have more recently been suggested to be members of the Cercozoa, a morphologically diverse group of amoeboid, flagellate, and amoeboflagellate protists. The recognition that Cercozoa constitute a monophyletic lineage has come from phylogenetic analyses of small subunit ribosomal RNA genes. Protein sequence data have suggested that the closest relatives of Cercozoa are the Foraminifera. To further test a cercozoan origin for the plasmodiophorids, we isolated actin genes from Plasmodiophora brassicae, Sorosphaera veronicae, and Spongospora subterranea, and polyubiquitin gene fragments from P. brassicae and S. subterranea. We also isolated actin genes from the chlorarachniophyte Lotharella globosa. In protein phylogenies of actin, the plasmodiophorid sequences consistently branch with Cercozoa and Foraminifera, and weakly branch as the sister group to the foraminiferans. The plasmodiophorid polyubiquitin sequences contain a single amino acid residue insertion at the functionally important processing point between ubiquitin monomers, the same place in which an otherwise unique insertion exists in the cercozoan and foraminiferan proteins. Taken together, these results indicate that plasmodiophorids are indeed related to Cercozoa and Foraminifera, although the relationships amongst these groups remain unresolved.

Phylogenetic diversity and whole-cell hybridization of oxymonad flagellates from the hindgut of the wood-feeding lower termite Reticulitermes flavipes.

SSU rRNA genes of oxymonad protists from the hindgut of the wood-feeding termite Reticulitermes flavipes were PCR-amplified using a newly designed oxymonad-specific forward primer and a newly designed reverse primer specific for termite gut flagellates. After cloning, the clone library was sorted into four groups by RFLP analysis and nearly full-length SSU rRNA gene sequences were obtained for representative clones from each group. Phylogenetic analysis revealed that sequences of all four groups formed a monophyletic cluster with the only other existing SSU rRNA gene sequence of oxymonads. Using whole-cell hybridization with clone-specific fluorescently labeled probes, each of the four clone groups could be assigned to a specific morphotype, which were identified as Dinenympha gracilis, Dinenympha fimbriata, and so-far undescribed species of Pyrsonympha and Dinenympha. Our results demonstrate that the morphological variety of oxymonads is not caused by the presence of different developmental stages of the same organism, but that the various morphotypes represent different species.

Eficiência de algumas estaçöes de tratamento de esgotos de Feira de Santana na remoçäo da carga orgânica, coliformes, helmintos e protozoários e situaçöes de risco de usuários a jusante do lançamento / Study of the persistence of helminthes and protozoa in affluent and effluent of sanitary sewer treatment station in Feira de Santana and the evaluation of the impact to the health of launching ebb tide users

É comum a ocupaçäo das margens dos recursos hídricos por pessoas que se utilizam das águas desses recursos para vários fins sem qualquer tratamento prévio, estando sujeitas a impactos à saúde devido à poluiçäo causada pelos lançamentos dos esgotos sanitários nesses corpos hídricos. Essa pesquisa visa caracterizar os afluentes e efluentes de quatro estaçöes de tratamento de esgotos sanitários de comunidades que dispöem dos serviços de abastecimento de água e esgotamento sanitário em Feira de Santana; verificar como ocorre a persistência de parasitas intestinais - helmintos e protozoários - nos esgotos sanitários dessas comunidades; avaliar a eficiência das estaçöes de tratamento estudadas quanto à remoçäo da carga orgânica e de coliformes; verificar a capacidade de remoçäo de microorganismos nos sistemas de tratamento de esgotos sanitários estudados e o que isso representa em termos de impacto à saúde dos usuários de jusante dos pontos de lançamentos de efluentes tratados. Trata-se de um estudo analítico, constituídos de levantamentos de parâmetros: físicos - temperatura, pH, vazäo -; químicos - DBO e DQO - e biológicos - coliformes totais e fecais, nove espécies de helmintos e seis espécies de protozoários, parasitos do intestino humano. As coletas de amostras foram realizadas uma vez por semana, durante o período de um ano, em quatro plantas de tratamento de esgotos selecionadas para estudo, em dois pontos - entrada e saída das mesmas. As análises foram executadas no Laboratório de Saneamento do Departamento de Tecnologia e no Laboratório de Parasitologia do Departamento de Biologia, ambos da UEFS - Universidade Estadual de Feira de Santana. Os resultados obtidos nos afluentes analisados mostram que nas comunidades pesquisadas há persistência de helmintos e protozoários, nas quatro estaçöes do ano; que a eficiência do tratamento nos diferentes sistemas de tratamento de esgotos estudados atende ou se aproxima das exigências previstas em Lei quanto à remoçäo de DBO e DQO; que a remoçäo de coliformes é baixa, embora atenda à exigência prevista em Lei do Estado da Bahia; e que parasitas dos grupos helmintos e protozoários näo säo retidos pelos sistemas de tratamento e säo lançados nos corpos receptores, impactando-os.

The evolution of parasites from their hosts: intra- and interspecific parasitism and Emery's rule.

In some taxa of Hymenoptera, fungi, red algae and mistletoe, parasites and their hosts are either sibling species or at least closely related (Emery's rule). Three evolutionary mechanisms have been proposed for this phenomenon: (i) intraspecific parasitism is followed by sympatric speciation; (ii) allopatric speciation is followed by secondary sympatry and the subsequent parasitism of one sibling species by the other; and (iii) allopatric speciation of a species with intraspecific parasitism is followed by secondary sympatry, in which one species becomes an obligate parasite of the other. Mechanisms (i) and (ii) are problematic, while mechanism (iii) has not, to our knowledge, been analysed quantitatively. In this paper, we develop a model for single- and two-species evolutionary stable strategies (ESSs) to examine the basis for Emery's rule and to determine whether mechanism (iii) is consistent with ESS reasoning. In secondary sympatry after allopatric speciation, the system's evolution depends on the relative abundances of the two sibling species and on the proportional damage wrought by parasites of each species on non-parasitic members of the other. Depending on these interspecific effects, either the rarer or the commoner species may become the parasite and the levels of within-species parasitism need not determine which evolves to obligate parasitism.

[Overview of tropical endoparasitic diseases with cutaneous manifestations]. / Survol des endoparasitoses tropicales à expression cutanée.

Among the diverse endoparasitic disorders some are primary cutaneous disorders and others exhibit signs on the skin in association with predominant internal manifestations. A variety of protozoans and helminths are responsible for these disorders.

Ichthyophthirius multifilis protozoa in gasteropelecus sternicola, Linnaeus 1758, collected in the area of Belém state of Pará Brazil

The present study describes for the first time Ichthyophthirius multifilis infecting twenty ornamental fishes Gasteropelecus sternicola (white butterfly fish). Parasites were found in 100 percent of examined fishes. Light microscopy and scanning electron microscopy (SEM) were used in this exam. SEM showed fins destroyed by the parasites action. High prevalence of the parasitism has a high concern as those fishes are of commercial importance for Brazil

Contaminaçäo por enteroparasitas em hortaliças comercializadas nas cidades de Niterói e Rio de Janeiro, Brasil / Intestinal parasites contamination from vegetables comercialized in Niterói and Rio de Janeiro cities, Brazil

O objetivo deste estudo foi avaliar a contaminaçäo por enteroparasitas em hortaliças consumidas cruas comercializadas nas cidades de Niterói e Rio de Janeiro. Foram estudadas 128 amostras de hortaliças - alface (Lactuca sativa) e agriäo (Nasturtium officinale) provenientes do comércio (supermercados, feiras-livre e quitandas) e de restaurantes tipo self-services. Apenas 6,2 por cento das amostras apresentaram presença de estruturas parasitárias com morfologia semelhante as de espécies parasitas de animais. Foi encontrado presença de contaminantes como ácaros, ovos de ácaros, insetos, larvas de nematóides e protozoários ciliados em quase todas as amostras (96,1 por cento), inclusive nas de restaurantes. Este alto percentual sugere a presença de risco de infecçäo, pois associado a esses agentes poderiam existir estruturas parasitárias infectantes para o homem

The effect of azadirachtin on Blastocrithidia triatomae and Trypanosoma cruzi in Triatoma infestans (Insecta, Hemiptera).

The effect of azadirachtin on Blastocrithidia triatomae and Trypanosoma cruzi, which colonise the intestinal tract of the blood-sucking bug Triatoma infestans, was investigated. In established infections of controls without azadirachtin treatment, the small intestine of fifth-instar T. infestans contained up to 7 x l0(6) B. triatomae and the rectum 3 x 10(6). In comparison to this homoxenous flagellate, the population densities of T. cruzi in the respective regions were 99.3 and 76% lower. Treatment with azadirachtin (1 microg ml(-1)) via a blood meal and a concurrent infection with B. triatomae resulted in an increase of the population density (3 weeks p.i.), caused mainly by the mastigote stages in the rectum. In an established B. triatomae infection (12 weeks p.i.), feeding of azadirachtin did not affect the population density and composition. In an optimal T. cruzi-vector system, i.e. parasite and bug originate from the same locality, the treatment with azadirachtin at 20 weeks p.i. strongly reduced the population density in the small intestine of all bugs up to 100 days after treatment, but only in a minor percentage of the bugs in the rectum. Trypanosoma (cruzi incubated for up to 24 h in faeces of azadirachtin-treated bugs were not affected, indicating that the rectum of these bugs contained no toxic substances. The importance of these findings is that investigations of the mechanisms of action of azadirachtin offer a possibility to identify vector-derived compounds, which are necessary for the development of T. cruzi, thereby, giving us a possible new strategy to combat Chagas' disease.