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1.
Nat Microbiol ; 6(2): 173-186, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33398100

RESUMO

Marine microeukaryotes play a fundamental role in biogeochemical cycling through the transfer of energy to higher trophic levels and vertical carbon transport. Despite their global importance, microeukaryote physiology, nutrient metabolism and contributions to carbon cycling across offshore ecosystems are poorly characterized. Here, we observed the prevalence of dinoflagellates along a 4,600-km meridional transect extending across the central Pacific Ocean, where oligotrophic gyres meet equatorial upwelling waters rich in macronutrients yet low in dissolved iron. A combined multi-omics and geochemical analysis provided a window into dinoflagellate metabolism across the transect, indicating a continuous taxonomic dinoflagellate community that shifted its functional transcriptome and proteome as it extended from the euphotic to the mesopelagic zone. In euphotic waters, multi-omics data suggested that a combination of trophic modes were utilized, while mesopelagic metabolism was marked by cytoskeletal investments and nutrient recycling. Rearrangement in nutrient metabolism was evident in response to variable nitrogen and iron regimes across the gradient, with no associated change in community assemblage. Total dinoflagellate proteins scaled with particulate carbon export, with both elevated in equatorial waters, suggesting a link between dinoflagellate abundance and total carbon flux. Dinoflagellates employ numerous metabolic strategies that enable broad occupation of central Pacific ecosystems and play a dual role in carbon transformation through both photosynthetic fixation in the euphotic zone and remineralization in the mesopelagic zone.


Assuntos
Ciclo do Carbono , Dinoflagelados/metabolismo , Água do Mar/parasitologia , Dinoflagelados/classificação , Oceano Pacífico , Filogenia , Proteínas de Protozoários/metabolismo
2.
Protist ; 171(4): 125743, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32731120

RESUMO

The phylum Perkinsozoa is known as an exclusively parasitic group including the parasites of shellfish, fish, dinoflagellates, cryptophytes, and tadpoles and at present comprises seven genera across three families (Parviluciferaceae, Perkinsidae, and Xcellidae), with the genus Parvilucifera having the most abundant species in the family Parviluciferaceae. During intensive sampling along the Korean coast in August and September 2017, a new species of the genus Parvilucifera was discovered and successfully established in cultures. Morphological and ultrastructural observations revealed that the new parasitoid shares almost all known diagnostic characters with other species of Parvilucifera, except that its sporangium has a higher number of apertures although with smaller diameters than those in P. infectans. Molecular phylogenetic trees based on both nuclear small subunit (SSU) and concatenated SSU and large subunit (LSU) ribosomal DNA (rDNA) sequences revealed that the new parasitoid was nested within the family Parviluciferaceae and had a sister relationship with P. infectans. Based on morphological, ultrastructural, and molecular data, we propose to erect a new species, P. multicavata sp. nov., for the new parasitoid found in this study.


Assuntos
Alveolados/classificação , Dinoflagelados/parasitologia , Filogenia , Alveolados/genética , Alveolados/ultraestrutura , DNA Ribossômico/genética , República da Coreia , Água do Mar/parasitologia , Especificidade da Espécie
3.
Eur J Protistol ; 75: 125717, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32585571

RESUMO

The loricate choanoflagellate genera Pleurasiga and Parvicorbicula are taxonomically ambiguous. Pleurasiga because of the uncertainty that relates to the true identity of the type species, and Parvicorbicula because too many newly described species over time have been dumped here in lack of better options. While all species currently allocated to the genus Pleurasiga (with the exception of the type species) are observed in our samples from the global warm water belt, the genus Parvicorbicula is represented by just a few and mostly infrequently recorded taxa. Two new species, viz. Pl. quadrangiella sp. nov. and Pl. minutissima sp. nov., are described here. While the former is closely related to Pl. echinocostata, the latter is reminiscent of Pl. minima. Core species of Pleurasiga and Parvicorbicula deviate from the vast majority of loricate choanoflagellates in having both the anterior and the mid-lorica transverse costae located exterior to the longitudinal costae. In Pl. quadrangiella there is no mid-lorica transverse costa but rather a small posterior transverse costa located inside the longitudinal costae. In Pl. minutissima the mid-lorica transverse costa has extensive costal strip overlaps which reveal patterns of costal strip junctions that deviate from the norm.


Assuntos
Coanoflagelados/classificação , Coanoflagelados/citologia , Distribuição Animal , Animais , Coanoflagelados/fisiologia , Temperatura Alta , Oceanos e Mares , Água do Mar/parasitologia , Especificidade da Espécie
4.
Protist ; 171(1): 125709, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32004979

RESUMO

This study investigated protist community composition and biotic interactions focusing on microplankton at four distinct sites around the Kerguelen Islands (Southern Ocean) after the summer phytoplankton bloom. Protist diversity in different size fractions, sampled with Niskin bottles and plankton nets, was assessed by sequencing of the V4 18S rDNA region. Combining different approaches, i.e. sequencing of different plankton size fractions, and isolation and sequencing of single cells, provided new insights into microbial interactions in protist communities. The communities displayed high variability, including short-term fluctuations in relative abundance of large protists (>35µm) highlighted by the plankton net samples. Size fractionation of protist communities showed high concentrations of free Syndiniales spores but relatively few Syndiniales associated with microplankton, suggesting low parasitic infection in early autumn. Co-variance network analyses and sequencing of individually isolated single cells highlighted the important role of Rhizaria as consumers of a wide range of different diatom taxa. The data also raised the hypothesis that different Syndiniales clades might be directly or indirectly associated with some diatom genera, thus suggesting a potentially wider host range of these parasites than has been previously reported. These associations and the potential impact on carbon fluxes are discussed.


Assuntos
Biodiversidade , Interações Hospedeiro-Parasita/fisiologia , Plâncton/classificação , Estações do Ano , Água do Mar/parasitologia , Eucariotos/fisiologia , Oceanos e Mares , Plâncton/genética , Plâncton/microbiologia , RNA Ribossômico 18S/genética , Água do Mar/microbiologia
5.
Eur J Protistol ; 73: 125665, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31978633

RESUMO

Cafeteria is one of the most common and ecologically significant genera of heterotrophic nanoflagellates in marine plankton. We could isolate and cultivate 29 strains morphologically similar to Cafeteria obtained from surface waters and the deep sea all over the world's ocean. Morphological characterization obtained by high resolution microscopy revealed only small differences between the strains. Sequencing the type material of the type species C. roenbergensis (CCAP 1900/1) and molecular analyses (18S rDNA, 28S rDNA) of newly isolated strains resulted in a revision and separation of the Cafeteriaceae into two known species (C. roenbergensis, C. mylnikovii) and six new species (C. maldiviensis, C. biegae, C. loberiensis, C. chilensis, C. graefeae, C. burkhardae). Many deposited Cafeteria sequences at GenBank and most of our own sequences clustered within one clade (C. burkhardae) with a p-distance of 5% to strain CCAP 1900/1. Only C. maldiviensis clustered together with the type species C. roenbergensis. While C. burkhardae seems to have a cosmopolitan distribution, the distribution of the other species seems to be more restricted. A strain from the Angola Basin had a p-distance of 10% to Cafeteria species and clustered separately within the Anoecales requiring the erection of a new genus, Bilabrum gen. nov., with B. latius sp. nov. as type species.


Assuntos
Filogenia , Estramenópilas/classificação , Oceanos e Mares , RNA Ribossômico 18S/genética , RNA Ribossômico 28S/genética , Água do Mar/parasitologia , Estramenópilas/citologia , Estramenópilas/genética
6.
Int J Parasitol ; 50(1): 75-83, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31857073

RESUMO

Bivalve molluscs are now considered indicator species of aquatic contamination by human parasitic protozoa. Nonetheless, the possible effects of these protozoa on the immune system of their paratenic hosts are poorly documented. The aim of this study was to evaluate the effects of two protozoa on hemocyte viability and phagocytosis from two mussels, the zebra mussel (freshwater habitat) and the blue mussel (seawater habitat). For these purposes, viability and phagocytic markers have been analysed on hemocytes from mussels without biological stress (control hemocytes), and on hemocytes exposed to a biological stress (Toxoplasma gondii and Cryptosporidium parvum oocysts). We report, for the first known time, the interactions between protozoa and hemocytes of mussels from different aquatic environments. Zebra mussel hemocytes showed a decrease in phagocytosis of fluorescent microbeads after exposure to both protozoa, while blue mussel hemocytes reacted only to T. gondii oocysts. These decreases in the ingestion of microbeads can be caused by competition between beads and oocysts and can be influenced by the size of the oocysts. New characterisations of their immune capacities, including aggregation, remain to be developed to understand the specificities of both mussels.


Assuntos
Dreissena/imunologia , Hemócitos/parasitologia , Mytilus edulis/imunologia , Fagocitose/fisiologia , Espécies Sentinelas , Animais , Cryptosporidium , Transmissão de Doença Infecciosa , Dreissena/citologia , Água Doce/parasitologia , Hemócitos/imunologia , Humanos , Imunidade Celular/fisiologia , Mytilus edulis/citologia , Água do Mar/parasitologia , Toxoplasma
7.
Eur J Protistol ; 72: 125663, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31869711

RESUMO

In this study, we investigated the morphology and molecular phylogeny of four marine or brackish spirotrichean ciliates found in China, namely: Caryotricha sinica sp. nov., Prodiscocephalus orientalis sp. nov., P. cf. borrori, and Certesia quadrinucleata. Caryotricha sinica is characterized by its small size, seven cirral rows extending posteriorly to about 65% of the cell length, and four transverse cirri. Prodiscocephalus orientalis differs from its congeners mainly by the number of cirri in the "head" region and on the ventral side. The SSU rDNA sequence of P. cf. borrori differs from that of other population of P. borrori by ca. 40 bp. Consequently, the nominal species P. borrori is considered to be a species-complex. New data are provided for Certesia quadrinucleata. The Chinese population of C. quadrinucleata, for example, has fewer left marginal cirri than the other populations for which such data are available. Phylogenetic analyses based on SSU rDNA sequence data show that the genus Caryotricha is monophyletic. All typical "discocephalids" with a discoid "head" form a strongly supported clade that is sister to the unstable uronychiids + pseudoamphisiellids clade within the Euplotia. The genus Certesia forms a sister group to the Euplotes clade, also within the Euplotia assemblage.


Assuntos
Cilióforos/classificação , Cilióforos/citologia , Filogenia , Água do Mar/parasitologia , China , Cilióforos/genética , Águas Salinas , Especificidade da Espécie
8.
Eur J Protistol ; 72: 125659, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31825791

RESUMO

Three species of tintinnines, namely Tintinnopsis tentaculata Nie and Cheng, 1947, Tintinnopsis orientalis Kofoid and Campbell, 1929, and Eutintinnus lususundae (Entz, 1885) Kofoid and Campbell, 1939, were isolated from coastal waters of China. The morphology of each was investigated based on observations of live and protargol-stained specimens, and their SSU rDNA- and LSU rDNA-based phylogenetic relationships were analyzed. The ciliary patterns of these species are revealed for the first time. Based on the original descriptions and data from the present study, an improved diagnosis is given for each species. Unlike its congeners, the second dorsal kinety of Eutintinnus lususundae is displaced below the left ciliary field, which may suggest that the second dorsal kinety is evolving into a posterior kinety by a migration process. The ventral kinety in Eutintinnus is redefined. A neotype is fixed for T. tentaculata to stabilize the species name objectively, mainly because of the unavailability of type material.


Assuntos
Cilióforos/classificação , Água do Mar/parasitologia , China , Cilióforos/citologia , Cilióforos/genética , DNA de Protozoário/genética , Filogenia , RNA Ribossômico 18S/genética , Subunidades Ribossômicas Maiores de Eucariotos/genética , Especificidade da Espécie
9.
Appl Environ Microbiol ; 86(3)2020 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-31732569

RESUMO

Human viruses are ubiquitous contaminants in surface waters, where they can persist over extended periods of time. Among the factors governing their environmental persistence, the control (removal or inactivation) by microorganisms remains poorly understood. Here, we determined the contribution of indigenous bacteria and protists to the decay of human viruses in surface waters. Incubation of echovirus 11 (E11) in freshwater from Lake Geneva and seawater from the Mediterranean Sea led to a 2.5-log10 reduction in the infectious virus concentration within 48 h at 22°C, whereas E11 was stable in sterile controls. The observed virus reduction was attributed to the action of both bacteria and protists in the biologically active matrices. The effect of microorganisms on viruses was temperature dependent, with a complete inhibition of microbial virus control in lake water at temperatures of ≤16°C. Among three protist isolates tested (Paraphysomonas sp., Uronema marinum, and Caecitellus paraparvulus), Caecitellus paraparvulus was particularly efficient at controlling E11 (2.1-log10 reduction over 4 days with an initial protist concentration of 103 cells ml-1). In addition, other viruses (human adenovirus type 2 and bacteriophage H6) exhibited different grazing kinetics than E11, indicating that the efficacy of antiviral action also depended on the type of virus. In conclusion, indigenous bacteria and protists in lake water and seawater can modulate the persistence of E11. These results pave the way for further research to understand how microorganisms control human viral pathogens in aquatic ecosystems and to exploit this process as a treatment solution to enhance microbial water safety.IMPORTANCE Waterborne human viruses can persist in the environment, causing a risk to human health over long periods of time. In this work, we demonstrate that in both freshwater and seawater environments, indigenous bacteria and protists can graze on waterborne viruses and thereby reduce their persistence. We furthermore demonstrate that the efficiency of the grazing process depends on temperature, virus type, and protist species. These findings may facilitate the design of biological methods for the disinfection of water and wastewater.


Assuntos
Cadeia Alimentar , Lagos , Viabilidade Microbiana , Viroses/virologia , Fenômenos Fisiológicos Virais , Doenças Transmitidas pela Água/virologia , Oceano Atlântico , Fenômenos Fisiológicos Bacterianos , Chrysophyta/fisiologia , Lagos/microbiologia , Lagos/parasitologia , Lagos/virologia , Mar Mediterrâneo , Oligoimenóforos/fisiologia , Água do Mar/microbiologia , Água do Mar/parasitologia , Água do Mar/virologia , Espanha , Especificidade da Espécie , Estramenópilas/fisiologia , Suíça , Vírus/classificação
10.
Eur J Protistol ; 72: 125643, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31734636

RESUMO

The colonization features of periphytic protozoa have proved to be a useful tool for indicating water quality status in aquatic ecosystems. In order to reveal the seasonal variations in colonization dynamics of the protozoa, a 1-year baseline survey was carried out in coastal waters of the Yellow Sea, northern China. Using glass slides as artificial substrates, a total of 240 slides were collected at a depth of 1 m in four seasons after colonization periods of 3, 7, 10, 14, 21, and 28 days. A total of 122 ciliate species were identified with 21 dominant species. The colonization dynamics of the protozoa were well fitted to the MacArthur-Wilson and logistic models in all four seasons (P < 0.05). However, the equilibrium species numbers (Seq), colonization rates (G), and the time to 90% Seq (T90%) represented a clear seasonal variability: (1) more or less similar levels in spring and autumn (Seq = 29/23; G = 0.301/0.296; T90%=7.650/7.779); (2) with a significant difference in summer and winter (Seq = 32/121; G = 0.708/0.005; T90% = 3.252/479.705). Multivariate approaches demonstrated that the exposure time for the species composition and community structure of the protozoa to an equilibrium period were 10-14 days in spring and autumn, but less and more time periods were needed in summer and winter, respectively. Based on the results, we suggest that the colonization dynamics of periphytic protozoa were different within four seasons, and an optimal sampling strategy for monitoring surveys should be modified during different seasons in marine ecosystems.


Assuntos
Biodiversidade , Cilióforos/fisiologia , Estações do Ano , Água do Mar/parasitologia , China , Monitoramento Ambiental , Modelos Logísticos
11.
Eur J Protistol ; 71: 125634, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31585231

RESUMO

Vannella samoroda n. sp. (Amoebozoa, Vannellida) was isolated from the mouth of the Malaya Samoroda river flowing into Elton, the largest European hypersaline lake (Russia). Among all rivers of the area, it has the highest salt content (ca. 110‰). Amoebae maintained in seawater medium with ca. 77‰ salts concentration had a set of morphological characters typical of Vannella spp.: rounded, fan-shaped, or spatulate locomotive form, floating form with bent, blunt-ended hyaline pseudopodia, and a cell coat consisting of regularly packed palisade elements and scarce simple filaments. Phylogenetic analyses based on SSU rRNA and cytochrome C oxidase subunit 1 genes show that the amoeba is most closely related to Vannella ebro Smirnov, 2001, but represents a distinct species. The clade of V. ebro and V. samoroda branches among marine species of Vannella. The studied species is the first member of the genus Vannella from a continental saline habitat described using molecular data. Interestingly, it has a broad range of salinity tolerance: cells reproduce above 18‰, while survival of a few cells regularly occurs even in highly diluted Prescott and James medium. The normal culture restores itself when PJ medium is substituted with 77‰ seawater medium even after months of experimental incubation.


Assuntos
Amebozoários/classificação , Filogenia , Água do Mar/parasitologia , Amebozoários/genética , Complexo IV da Cadeia de Transporte de Elétrons/genética , RNA Ribossômico 18S/genética , Federação Russa , Especificidade da Espécie
12.
Parasit Vectors ; 12(1): 472, 2019 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-31604479

RESUMO

BACKGROUND: The parasitic dinoflagellates of the genus Hematodinium represent the causative agent of so-called bitter or pink crab disease in a broad range of shellfish taxa. Outbreaks of Hematodinium-associated disease can devastate local fishing and aquaculture efforts. The goal of our study was to examine the potential role of the common shore (green) crab Carcinus maenas as a reservoir for Hematodinium. Carcinus maenas is native to all shores of the UK and Ireland and the North East Atlantic but has been introduced to, and subsequently invaded waters of, the USA, South Africa and Australia. This species is notable for its capacity to harbour a range of micro- and macro-parasites, and therefore may act as a vector for disease transfer. METHODS: Over a 12-month period, we interrogated 1191 crabs across two distinct locations (intertidal pier, semi-closed dock) in Swansea Bay (Wales, UK) for the presence and severity of Hematodinium in the haemolymph, gills, hepatopancreas and surrounding waters (eDNA) using PCR-based methods, haemolymph preparations and histopathology. RESULTS: Overall, 13.6% were Hematodinium-positive via PCR and confirmed via tissue examination. Only a small difference was observed between locations with 14.4% and 12.8% infected crabs in the Dock and Pier, respectively. Binomial logistic regression models revealed seasonality (P < 0.002) and sex (P < 0.001) to be significant factors in Hematodinium detection with peak infection recorded in spring (March to May). Male crabs overall were more likely to be infected. Phylogenetic analyses of the partial ITS and 18S rRNA gene regions of Hematodinium amplified from crabs determined the causative agent to be the host generalist Hematodinium sp., which blights several valuable crustaceans in the UK alone, including edible crabs (Cancer pagurus) and langoustines (Nephrops norvegicus). CONCLUSIONS: Shore crabs were infected with the host generalist parasite Hematodinium sp. in each location tested, thereby enabling the parasite to persist in an environment shared with commercially important shellfish.


Assuntos
Alveolados/patogenicidade , Braquiúros/parasitologia , Reservatórios de Doenças/parasitologia , Alveolados/classificação , Alveolados/genética , Alveolados/fisiologia , Animais , Distribuição Binomial , DNA Espaçador Ribossômico/genética , Dinoflagelados/classificação , Dinoflagelados/genética , Dinoflagelados/patogenicidade , Dinoflagelados/fisiologia , Feminino , Brânquias/parasitologia , Hemolinfa/química , Hemolinfa/parasitologia , Modelos Logísticos , Masculino , Filogenia , Reação em Cadeia da Polimerase , RNA Ribossômico 18S/análise , Estações do Ano , Água do Mar/parasitologia , País de Gales
13.
Eur J Protistol ; 71: 125632, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31563814

RESUMO

Aided by an extensive collection of specimens from warm water seas, it has been possible to revisit the loricate choanoflagellate genus Cosmoeca. While the type species C. norvegica and also C. ventricosa sensu stricto have been described from temperate North Atlantic realms and share a cosmopolitan distribution, the remaining species and morphotypes of Cosmoeca are largely confined to warmer waters. The new data broadly validates the initial circumscription of species of Cosmoeca. The persisting taxonomic puzzle with respect to C. ventricosa, which in addition to the core type accommodates no less than five different morphotypes (form A-E), has been further elucidated. The Cosmoeca paper is part of a 'monographic' series of warm water loricate choanoflagellate contributions in progress, where the aim is to provide the best possible account of warm water species diversity, based on traditional light and electron microscopical techniques, as a tool for future identification work based on microscopy, and in support of the work in progress with establishing a quality assured molecular tool for future recognition of diversity.


Assuntos
Biodiversidade , Coanoflagelados/classificação , Temperatura Alta , Coanoflagelados/citologia , Coanoflagelados/ultraestrutura , Água do Mar/parasitologia , Especificidade da Espécie
14.
Eur J Protistol ; 71: 125635, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31553939

RESUMO

The morphology, infraciliature, and silverline system of two peritrich ciliates, Pseudovorticella littoralis sp. n. and P. alani sp. n., isolated from coastal waters of southern China, were investigated based on both living and silver-stained specimens. Pseudovorticella littoralis sp. n. is characterized by the following combination of characters: cell inverted cone-shaped; contractile vacuole ventral; J-shaped macronucleus; infundibular polykinety 3 with two kinetosome rows of equal length; 19-26 silverlines from peristome to trochal band and 5-14 from trochal band to scopula. Pseudovorticella alani sp. n. is characterized by: cell inverted bell-shaped; contractile vacuole ventral; J-shaped macronucleus recurved almost forming a loop; infundibular polykinety 3 with three kinetosome rows, outer two rows longer than inner one; 48-61 silverlines between peristome and aboral trochal band, and 12-20 between aboral trochal band and scopula. The SSU rDNA sequences of both new species are reported and their genetic distances with congeners and phylogenetic relationships are investigated. Pseudovorticella and Epicarchesium cluster into two subclades with low support values. One subclade contains nearly all the available sequences of Pseudovorticella and Epicarchesium. Another one contains P. monilata and E. pectinatum. This calls on the need of a generic re-classification of Pseudovorticella and Epicarchesium based on more morphological and molecular data.


Assuntos
Oligoimenóforos/classificação , Filogenia , Água do Mar/parasitologia , China , Oligoimenóforos/citologia , Oligoimenóforos/genética , RNA Ribossômico 18S/genética , Especificidade da Espécie
15.
Eur J Protistol ; 71: 125633, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31520849

RESUMO

Loricate choanoflagellate genera that incorporate flattened costal strips in the lorica (i.e. Calotheca, Stephanacantha, Thomsenella (= Platypleura) and Syndetophyllum) are prevalent in warm water habitats. The genus Thomsenella (=Platypleura) thus comprises four species and three of these have an Andaman Sea type locality. Our ongoing examination of loricate choanoflagellate material from all major warm water oceans has provided us with the opportunity of revisiting species of Thomsenella in order to test and fortunately verify, in a morpho-specific context, the robustness of the species matrix initially defined.


Assuntos
Coanoflagelados/classificação , Temperatura Alta , Água do Mar/parasitologia , Coanoflagelados/citologia , Coanoflagelados/fisiologia , Ecossistema , Especificidade da Espécie
16.
Acta Parasitol ; 64(3): 528-543, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31270659

RESUMO

BACKGROUND: Of the 43 valid species of Rhadinorhynchus Lühe, 1911, 20 species are now known from the Pacific Ocean off Australia, Japan, and Vietnam. We have already described over 50 species and higher taxa from the Pacific Ocean off Vietnam over the last 15 years. PURPOSE: The present research is a continuation of our efforts to taxonomically map new acanthocephalan taxa, especially from Vietnam. Some of our collections in 2016 and 2017 revealed the presence of new species of the genus Rhadinorhynchus from various species of marine fish off the Pacific coast of Vietnam. We provide descriptions of these new species here. METHODS: Standard methods of collection and examination of marine hosts, processing and illustrating of specimens, and taxonomic identification of parasites using the extensive collections of the lead author were used. Type specimens were deposited at the Harold W. Manter Lab. collection, Lincoln, Nebraska. RESULTS: Three species Rhadinorhynchus are described from marine fish off the Vietnamese coast. Rhadinorhynchus circumspinus n. sp. with fusiform trunk, 1 field of anterior trunk spines, and anteriorly globular proboscis with up to 21 dorsoventrally differentiated hooks in 17-18 rows is described from Triacanthus biaculeatus Bloch (Triacanthidae) off Hai Phong. Rhadinorhynchus pacificus n. sp. with cylidrical trunk and proboscis with up to 25 dorso-ventrally similar hooks in 14-18 rows and trunk spines in 2 fields of dorsal, ventral and lateral spines is described from Auxis thazard (Lacepède) and Auxis rochei (Lacepède) (Scombridae) off Nha Trang. Rhadinorhynchus multispinosus n. sp. with cylindrical trunk and proboscis with up to 32 dorso-ventrally differentiated hooks in 12 rows, and many trunk spines in 2 fields of dorsal, ventral and lateral spines is described from Decapterus maruadsi (Temminck and Schlegel) (Carangidae) also off Hai Phong. Rhadinorhynchus polynemi Smales, 2014 of Australia is not the Indian species (with smallest basal hooks) as the basal hooks are largest and is now named Rhadinorhynchus australis nom. nov. (=Rhadinorhynchus polynemi Smales, 2014). Rhadinorhynchus trivandricus George and Nadakal, 1978 with smallest basal hooks and 8 pyriform cement glands is relegated to genus Indorhynchus Golvan, 1969. CONCLUSIONS: With the description of these 3 new species, the numner of valid species of Rhadinorhynchus has now increased to 46. We include a new generic diagnosis to accommodate the increased knowledge of variability within this genus.


Assuntos
Acantocéfalos/isolamento & purificação , Doenças dos Peixes/parasitologia , Helmintíase Animal/parasitologia , Acantocéfalos/classificação , Acantocéfalos/genética , Acantocéfalos/crescimento & desenvolvimento , Animais , Feminino , Masculino , Oceano Pacífico , Perciformes/classificação , Perciformes/parasitologia , Água do Mar/parasitologia , Vietnã
17.
Acta Parasitol ; 64(3): 596-602, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31187389

RESUMO

INTRODUCTION: Ceratomyxa Thélohan, 1892 is one of the largest genera under Myxosporea Butschli, 1881, and has a worldwide distribution, but little attention has been paid to myxosporean parasites from the Chinese seawaters, East China Sea. METHODS: Morphology and molecular biology methods were combined for species identification and phylogenetic analysis. RESULTS: A new coelozoic myxosporean species, Ceratomyxa siganicola n. sp., was found to infect the gallbladder of Siganus fuscescens (Houttuyn, 1782) (Perciformes, Siganidae) from coastal waters of Xiamen, East China Sea, China. Mature myxospores of the novel species exhibited the morphologically typical features of the genus Ceratomyxa. They were slightly crescent shaped with rounded ends, measuring 5.6 ± 0.5 (4.8-6.5) µm in length and 19.1 ± 1.8 (16.0-22.1) µm in thickness. The posterior angle was slightly convex to straight and measured 177.1 ± 0.5 (175.2-178.4)°. Spore valves were slightly unequal and smoothly ovoid in the lateral view. Two polar capsules were spherical, equal in size and measured 2.7 ± 0.2 (2.1-3.0) µm in diameter. The 18S rDNA sequence of C. siganicola n. sp. was unique among all myxozoans, and the highest similarity was 97.4% with Ceratomyxa barnesi. Phylogenetic analysis showed that C. siganicola n. sp. was clustered within the clade of siganid ceratomyxids. The present results also indicated that the species radiation of Ceratomyxa occurred not only within host affinity but also within locality.


Assuntos
Doenças dos Peixes/parasitologia , Myxozoa/genética , Myxozoa/isolamento & purificação , Doenças Parasitárias em Animais/parasitologia , Animais , China , Feminino , Peixes/classificação , Peixes/parasitologia , Vesícula Biliar/parasitologia , Masculino , Myxozoa/classificação , Myxozoa/crescimento & desenvolvimento , Filogenia , Água do Mar/parasitologia
18.
Eur J Protistol ; 70: 1-16, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31176174

RESUMO

Although it is widely recognized that oligotrich ciliates are the dominant constituent of microzooplankton communities and perform key functions in energy flow and material cycling in marine microbial food webs, knowledge of their diversity is scant. In the present study, we investigate the oligotrich genera, Cyrtostrombidium and Apostrombidium, with emphasis on their morphology and evolutionary relationships. Three isolates were collected from coastal waters of northern and southern China including two new species, viz., Cyrtostrombidium paraboreale sp. n., Apostrombidium orientale sp. n., and Apostrombidium pseudokielum Xu et al., 2009. Cyrtostrombidium paraboreale sp. n. is characterized by possessing 64-98 cytopharyngeal rods and two macronuclear nodules. Apostrombidium orientale sp. n. is characterized by its somatic kinety consisting of five fragments including a horizontally orientated subterminal fragment and possessing conspicuously long dorsal cilia. Apostrombidium pseudokielum is redescribed based on the new population and a re-examination of the type material. Phylogenetic analyses were performed for the subclass Oligotrichia, incorporating SSU rRNA gene sequences of the three species investigated here. The results indicate that the genus Cyrtostrombidium is monophyletic with C. paraboreale sp. n. occupying the basal position. The genus Apostrombidium is not monophyletic as Varistrombidium kielum is nested within it.


Assuntos
Organismos Aquáticos/classificação , Cilióforos/classificação , Filogenia , Organismos Aquáticos/citologia , Organismos Aquáticos/genética , China , Cilióforos/citologia , Cilióforos/genética , DNA de Protozoário/genética , DNA Ribossômico/genética , Água do Mar/parasitologia , Especificidade da Espécie
19.
J Eukaryot Microbiol ; 66(6): 966-980, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31166639

RESUMO

The deep sea has long been a mysterious and attractive habitat for protistologists. However, logistical difficulties severely limit sampling opportunities. Consequently, our knowledge of the protists in the deep sea, (arguably the largest habitat on earth), is relatively sparse. Here, we present a unique time-series concerning three different protist taxa that share only the characteristics of being relatively large, robust to sampling, and easily identifiable to species level using light microscopy: tintinnid ciliates, phaeogromid cercozoans (e.g. Challengerids) and amphisolenid dinoflagellates. We sampled a near-shore deep water site in the N.W. Mediterranean Sea at 250 m depth over a 2-yr period at approximately weekly intervals from January 2017 to December 2018. To our knowledge, no previous studies have employed sampling on a similar time scale. We found taxa that appear to be restricted to deep waters, distinct seasonal patterns of abundance in some taxa, and in others nonseasonal successional patterns. Based on data from sampling following a flash flood event, the Challengerid population appeared to respond positively to a pulse of terrigenous input. Some of the distinct mesopelagic tintinnid ciliates and amphisolinid dinoflagellates were also found in two samples from the North Atlantic mesopelagic gathered from near the Azores Islands in September 2018. We conclude that there are a variety of protist taxa endemic to the mesopelagic, that the populations are dynamic, and they may be widely distributed in the deep waters of the world ocean.


Assuntos
Cercozoários/isolamento & purificação , Cilióforos/isolamento & purificação , Dinoflagelados/isolamento & purificação , Água do Mar/parasitologia , Biodiversidade , Ecossistema , Mar Mediterrâneo , Dinâmica Populacional , Estações do Ano
20.
Appl Environ Microbiol ; 85(14)2019 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-31053582

RESUMO

For photosynthetic microbial eukaryotes, the rate-limiting step in NO3 - assimilation is its reduction to nitrite (NO2 -), which is catalyzed by assimilatory nitrate reductase (NR). Oceanic productivity is primarily limited by available nitrogen and, although nitrate is the most abundant form of available nitrogen in oceanic waters, little is known about the identity of microbial eukaryotes that take up nitrate. This lack of knowledge is especially severe for ice-covered seas that are being profoundly affected by climate change. To address this, we examined the distribution and diversity of NR genes in the Arctic region by way of clone libraries and data mining of available metagenomes (total of 4.24 billion reads). We directly compared NR clone phylogenies with the V4 region of the 18S rRNA gene (DNA pool) and 18S rRNA (RNA pool) at two ice-influenced stations in the Canada Basin (Beaufort Sea). The communities from the two nucleic acid templates were similar at the level of major groups, and species identified by way of NR gene phylogeny and microscopy were a subset of the 18S results. Most NR genes from arctic clone libraries matched diatoms and chromist nanoflagellates, including novel clades, while the NR genes in arctic eukaryote metagenomes were dominated by chlorophyte NR, in keeping with the ubiquitous occurrence of Mamiellophyceae in the Arctic Ocean. Overall, these data suggest that a dynamic and mixed eukaryotic community utilizes nitrate across the Arctic region, and they show the potential utility of NR as a tool to identify ongoing changes in arctic photosynthetic communities.IMPORTANCE To better understand the diversity of primary producers in the Arctic Ocean, we targeted a nitrogen cycle gene, NR, which is required for phytoplankton to assimilate nitrate into organic forms of nitrogen macromolecules. We compared this to the more detailed taxonomy from ice-influenced stations using a general taxonomic gene (18S rRNA). NR genes were ubiquitous and could be classified as belonging to diatoms, dinoflagellates, other flagellates, chlorophytes, and unknown microbial eukaryotes, suggesting novel diversity of both species and metabolism in arctic phytoplankton.


Assuntos
Biodiversidade , Eucariotos/metabolismo , Plâncton/metabolismo , Água do Mar , Organismos Aquáticos/metabolismo , Regiões Árticas , Canadá , DNA Ribossômico/análise , Sequenciamento de Nucleotídeos em Larga Escala , Microbiota , RNA Ribossômico 18S/análise , Água do Mar/microbiologia , Água do Mar/parasitologia
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