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1.
Eur J Protistol ; 73: 125688, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32143143

RESUMO

The molecular divergence, morphology and pathology of a cryptic gregarine that is related to the bee parasite Apicystis bombi Lipa and Triggiani, 1996 is described. The 18S ribosomal DNA gene sequence of the new gregarine was equally dissimilar to that of A. bombi and the closest related genus Mattesia Naville, 1930, although phylogenetic analysis supported a closer relation to A. bombi. Pronounced divergence with A. bombi was found in the ITS1 sequence (69.6% similarity) and seven protein-coding genes (nucleotide 78.05% and protein 90.2% similarity). The new gregarine was isolated from a Bombus pascuorum Scopoli, 1763 female and caused heavy hypertrophism of the fat body tissue in its host. In addition, infected cells of the hypopharyngeal gland tissue, an important excretory organ of the host, were observed. Mature oocysts were navicular in shape and contained four sporozoites, similar to A. bombi oocysts. Given these characteristics, we proposed the name Apicystis cryptica sp. n. Detections so far indicated that distribution and host species occupation of Apicystis spp. overlap at least in Europe, and that historical detections could not discriminate between them. Specific molecular assays were developed that can be implemented in future pathogen screens that aim to discriminate Apicystis spp. in bees.


Assuntos
Apicomplexa/classificação , Abelhas/parasitologia , Animais , Apicomplexa/citologia , Apicomplexa/genética , DNA de Protozoário/genética , Europa (Continente) , Corpo Adiposo/parasitologia , Oocistos/citologia , Especificidade da Espécie
2.
J Eukaryot Microbiol ; 67(1): 4-17, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31231936

RESUMO

Eugregarines are understudied apicomplexan parasites of invertebrates inhabiting marine, freshwater, and terrestrial environments. Most currently known terrestrial eugregarines have been described parasitizing the gut from less than 1% of total insect diversity, with a high likelihood that the remaining insect species are infected. Eugregarine diversity in orthopterans (grasshoppers, locusts, katydids, and crickets) is still little known. We carried out a survey of the eugregarines parasitizing the Mexican lubber grasshopper, Taeniopoda centurio, an endemic species to the northwest of Mexico. We described two new eugregarine species from the gut of the host: Amoebogregarina taeniopoda n. sp. and Quadruspinospora mexicana n. sp. Both species are morphologically dissimilar in their life-cycle stages. Our SSU rDNA phylogenetic analysis showed that both species are phylogenetically distant to each other, even though they parasitize the same host. Amoebogregarina taeniopoda n. sp. clustered within the clade Gregarinoidea, being closely related to Amoebogregarina nigra from the grasshopper Melanoplus differentialis. Quadruspinospora mexicana n. sp. clustered within the clade Actinocephaloidea and grouped with Prismatospora evansi, a parasite from dragonfly naiads. Amoebogregarina taeniopoda n. sp. and Q. mexicana n. sp. represent the first record of eugregarines found to infect a species of the family Romaleidae.


Assuntos
Apicomplexa/classificação , Apicomplexa/citologia , Gafanhotos/parasitologia , Interações Hospedeiro-Parasita , Filogenia , Animais , Apicomplexa/ultraestrutura , DNA de Protozoário/análise , DNA Ribossômico/análise , México , Microscopia , Microscopia Eletrônica de Varredura , Análise de Sequência de DNA
3.
Nature ; 568(7750): 103-107, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30944491

RESUMO

Apicomplexa is a group of obligate intracellular parasites that includes the causative agents of human diseases such as malaria and toxoplasmosis. Apicomplexans evolved from free-living phototrophic ancestors, but how this transition to parasitism occurred remains unknown. One potential clue lies in coral reefs, of which environmental DNA surveys have uncovered several lineages of uncharacterized basally branching apicomplexans1,2. Reef-building corals have a well-studied symbiotic relationship with photosynthetic Symbiodiniaceae dinoflagellates (for example, Symbiodinium3), but the identification of other key microbial symbionts of corals has proven to be challenging4,5. Here we use community surveys, genomics and microscopy analyses to identify an apicomplexan lineage-which we informally name 'corallicolids'-that was found at a high prevalence (over 80% of samples, 70% of genera) across all major groups of corals. Corallicolids were the second most abundant coral-associated microeukaryotes after the Symbiodiniaceae, and are therefore core members of the coral microbiome. In situ fluorescence and electron microscopy confirmed that corallicolids live intracellularly within the tissues of the coral gastric cavity, and that they possess apicomplexan ultrastructural features. We sequenced the genome of the corallicolid plastid, which lacked all genes for photosystem proteins; this indicates that corallicolids probably contain a non-photosynthetic plastid (an apicoplast6). However, the corallicolid plastid differs from all other known apicoplasts because it retains the four ancestral genes that are involved in chlorophyll biosynthesis. Corallicolids thus share characteristics with both their parasitic and their free-living relatives, which suggests that they are evolutionary intermediates and implies the existence of a unique biochemistry during the transition from phototrophy to parasitism.


Assuntos
Antozoários/parasitologia , Apicomplexa/genética , Apicomplexa/metabolismo , Clorofila/biossíntese , Genes de Protozoários/genética , Filogenia , Animais , Apicomplexa/citologia , Recifes de Corais , Dinoflagelados/citologia , Dinoflagelados/genética , Dinoflagelados/metabolismo , Genoma de Protozoário/genética , Fotossíntese , Plastídeos/genética , Simbiose
4.
Trends Parasitol ; 34(9): 759-771, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30078701

RESUMO

Increased parasite burden is linked to the severity of clinical disease caused by Apicomplexa parasites such as Toxoplasma gondii, Plasmodium spp, and Cryptosporidium. Pathogenesis of apicomplexan infections is greatly affected by the growth rate of the parasite asexual stages. This review discusses recent advances in deciphering the mitotic structures and cell cycle regulatory factors required by Apicomplexa parasites to replicate. As the molecular details become clearer, it is evident that the highly unconventional cell cycles of these parasites is a blending of many ancient and borrowed elements, which were then adapted to enable apicomplexan proliferation in a wide variety of different animal hosts.


Assuntos
Apicomplexa/citologia , Apicomplexa/fisiologia , Ciclo Celular , Interações Hospedeiro-Parasita , Infecções por Protozoários/parasitologia
5.
PLoS One ; 12(6): e0179709, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28640849

RESUMO

Recent studies on motility of Apicomplexa concur with the so-called glideosome concept applied for apicomplexan zoites, describing a unique mechanism of substrate-dependent gliding motility facilitated by a conserved form of actomyosin motor and subpellicular microtubules. In contrast, the gregarines and blastogregarines exhibit different modes and mechanisms of motility, correlating with diverse modifications of their cortex. This study focuses on the motility and cytoskeleton of the blastogregarine Siedleckia nematoides Caullery et Mesnil, 1898 parasitising the polychaete Scoloplos cf. armiger (Müller, 1776). The blastogregarine moves independently on a solid substrate without any signs of gliding motility; the motility in a liquid environment (in both the attached and detached forms) rather resembles a sequence of pendular, twisting, undulation, and sometimes spasmodic movements. Despite the presence of key glideosome components such as pellicle consisting of the plasma membrane and the inner membrane complex, actin, myosin, subpellicular microtubules, micronemes and glycocalyx layer, the motility mechanism of S. nematoides differs from the glideosome machinery. Nevertheless, experimental assays using cytoskeletal probes proved that the polymerised forms of actin and tubulin play an essential role in the S. nematoides movement. Similar to Selenidium archigregarines, the subpellicular microtubules organised in several layers seem to be the leading motor structures in blastogregarine motility. The majority of the detected actin was stabilised in a polymerised form and appeared to be located beneath the inner membrane complex. The experimental data suggest the subpellicular microtubules to be associated with filamentous structures (= cross-linking protein complexes), presumably of actin nature.


Assuntos
Apicomplexa/citologia , Apicomplexa/fisiologia , Citoesqueleto/efeitos dos fármacos , Citoesqueleto/metabolismo , Movimento/efeitos dos fármacos , Apicomplexa/efeitos dos fármacos , Apicomplexa/ultraestrutura , Microscopia , Trofozoítos/efeitos dos fármacos , Trofozoítos/fisiologia
6.
Cell Host Microbe ; 20(6): 731-743, 2016 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-27978434

RESUMO

Apicomplexa exhibit a unique form of substrate-dependent gliding motility central for host cell invasion and parasite dissemination. Gliding is powered by rearward translocation of apically secreted transmembrane adhesins via their interaction with the parasite actomyosin system. We report a conserved armadillo and pleckstrin homology (PH) domain-containing protein, termed glideosome-associated connector (GAC), that mediates apicomplexan gliding motility, invasion, and egress by connecting the micronemal adhesins with the actomyosin system. TgGAC binds to and stabilizes filamentous actin and specifically associates with the transmembrane adhesin TgMIC2. GAC localizes to the apical pole in invasive stages of Toxoplasma gondii and Plasmodium berghei, and apical positioning of TgGAC depends on an apical lysine methyltransferase, TgAKMT. GAC PH domain also binds to phosphatidic acid, a lipid mediator associated with microneme exocytosis. Collectively, these findings indicate a central role for GAC in spatially and temporally coordinating gliding motility and invasion.


Assuntos
Apicomplexa/citologia , Apicomplexa/fisiologia , Lipídeos , Proteínas dos Microfilamentos/fisiologia , Proteínas Motores Moleculares/fisiologia , Proteínas de Protozoários/fisiologia , Citoesqueleto de Actina/fisiologia , Actinas/fisiologia , Animais , Apicomplexa/metabolismo , Moléculas de Adesão Celular/fisiologia , Movimento Celular , Exocitose/fisiologia , Proteínas de Membrana/metabolismo , Proteínas de Membrana/fisiologia , Metiltransferases/metabolismo , Proteínas dos Microfilamentos/metabolismo , Modelos Moleculares , Organelas , Ácidos Fosfatídicos/metabolismo , Plasmodium berghei/metabolismo , Plasmodium berghei/fisiologia , Conformação Proteica , Infecções por Protozoários/parasitologia , Proteínas de Protozoários/metabolismo , Coelhos , Toxoplasma/citologia , Toxoplasma/metabolismo , Toxoplasma/fisiologia , Toxoplasmose/parasitologia
7.
Protist ; 167(3): 279-301, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-27239726

RESUMO

Urosporids (Apicomplexa: Urosporidae) are eugregarines that parasitise marine invertebrates, such as annelids, molluscs, nemerteans and echinoderms, inhabiting their coelom and intestine. Urosporids exhibit considerable morphological plasticity, which correlates with their different modes of motility and variations in structure of their cortical zone, according to the localisation within the host. The gregarines Urospora ovalis and U. travisiae from the marine polychaete Travisia forbesii were investigated with an emphasis on their general morphology and phylogenetic position. Solitary ovoid trophozoites and syzygies of U. ovalis were located free in the host coelom and showed metabolic activity, a non-progressive movement with periodic changes of the cell shape. Solitary trophozoites of U. travisiae, attached to the host tissue or free floating in the coelom, were V-shaped. Detached trophozoites demonstrated gliding motility, a progressive movement without observable cell body changes. In both gregarines, the cortex formed numerous epicytic folds, but superfolds appeared exclusively on the surface of U. ovalis during metabolic activity. SSU rDNA sequences obtained from U. ovalis and U. travisiae revealed that they belong to the Lecudinoidea clade; however, they are not affiliated with other coelomic urosporids (Pterospora spp. and Lithocystis spp.), but surprisingly with intestinal lecudinids (Difficilina spp.) parasitising nemerteans.


Assuntos
Apicomplexa/classificação , Apicomplexa/isolamento & purificação , Poliquetos/parasitologia , Animais , Apicomplexa/citologia , Apicomplexa/genética , Análise por Conglomerados , DNA de Protozoário/química , DNA de Protozoário/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Locomoção , Microscopia , Filogenia , RNA Ribossômico 18S/genética , Análise de Sequência de DNA
8.
Annu Rev Microbiol ; 69: 129-44, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26092225

RESUMO

Apicomplexa are known to contain greatly reduced organellar genomes. Their mitochondrial genome carries only three protein-coding genes, and their plastid genome is reduced to a 35-kb-long circle. The discovery of coral-endosymbiotic algae Chromera velia and Vitrella brassicaformis, which share a common ancestry with Apicomplexa, provided an opportunity to study possibly ancestral forms of organellar genomes, a unique glimpse into the evolutionary history of apicomplexan parasites. The structurally similar mitochondrial genomes of Chromera and Vitrella differ in gene content, which is reflected in the composition of their respiratory chains. Thus, Chromera lacks respiratory complexes I and III, whereas Vitrella and apicomplexan parasites are missing only complex I. Plastid genomes differ substantially between these algae, particularly in structure: The Chromera plastid genome is a linear, 120-kb molecule with large and divergent genes, whereas the plastid genome of Vitrella is a highly compact circle that is only 85 kb long but nonetheless contains more genes than that of Chromera. It appears that organellar genomes have already been reduced in free-living phototrophic ancestors of apicomplexan parasites, and such reduction is not associated with parasitism.


Assuntos
Alveolados/citologia , Alveolados/genética , Apicomplexa/citologia , Apicomplexa/genética , Apicomplexa/metabolismo , Transporte de Elétrons , Genoma Mitocondrial , Plastídeos/genética , Plastídeos/metabolismo , Simbiose
9.
Int J Syst Evol Microbiol ; 65(8): 2598-2614, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25985834

RESUMO

The eugregarines are a group of apicomplexan parasites that mostly infect the intestines of invertebrates. The high level of morphological variation found within and among species of eugregarines makes it difficult to find consistent and reliable traits that unite even closely related lineages. Based mostly on traits observed with light microscopy, the majority of described eugregarines from marine invertebrates has been classified into a single group, the Lecudinidae. Our understanding of the overall diversity and phylogenetic relationships of lecudinids is very poor, mainly because only a modest amount of exploratory research has been done on the group and very few species of lecudinids have been characterized at the molecular phylogenetic level. In an attempt to understand the diversity of marine gregarines better, we surveyed lecudinids that infect the intestines of Pacific ascidians (i.e. sea squirts) using ultrastructural and molecular phylogenetic approaches; currently, these species fall within one genus, Lankesteria. We collected lecudinid gregarines from six ascidian host species, and our data demonstrated that each host was infected by a different species of Lankesteria: (i) Lankesteria hesperidiiformis sp. nov., isolated from Distaplia occidentalis, (ii) Lankesteria metandrocarpae sp. nov., isolated from Metandrocarpa taylori, (iii) Lankesteria halocynthiae sp. nov., isolated from Halocynthia aurantium, (iv) Lankesteria herdmaniae sp. nov., isolated from Herdmania momus, (v) Lankesteria cf. ritterellae, isolated from Ritterella rubra, and (vi) Lankesteria didemni sp. nov., isolated from Didemnum vexillum. Visualization of the trophozoites with scanning electron microscopy showed that four of these species were covered with epicytic folds, whereas two of the species were covered with a dense pattern of epicytic knobs. The molecular phylogenetic data suggested that species of Lankesteria with surface knobs form a clade that is nested within a paraphyletic assemblage species of Lankesteria with epicytic folds.


Assuntos
Apicomplexa/classificação , Intestinos/parasitologia , Filogenia , Urocordados/parasitologia , Animais , Apicomplexa/citologia , Apicomplexa/isolamento & purificação , DNA de Protozoário/genética , Genes de RNAr , Microscopia Eletrônica de Varredura , Dados de Sequência Molecular , Oceano Pacífico , Análise de Sequência de DNA , Trofozoítos/citologia
10.
Parasitology ; 142(6): 816-26, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25736219

RESUMO

The uniform morphology of the developmental stages of Haemogregarina species and the insufficient information supplied by the simplistic descriptions of previous authors complicates their differential diagnosis and proper species identification. In this study, we detected Haemogregarina spp. in 6 out of 22 (27.2%) examined turtles originating from Southeast Asia, Malayemys subtrijuga (n = 4), Sacalia quadriocellata (n = 1) and Platysternon megacephalum (n = 1), and compared them with the available literature data. Microscopic analysis of our isolates distinguished 2 morphological species, Haemogregarina pellegrini and one new species, being described in this paper as Haemogregarina sacaliae sp. n. Phylogenetic analyses based on 1210 bp long fragment of 18S rDNA sequences placed both haemogregarines firmly within the monophyletic Haemogregarina clade. Isolates of H. pellegrini from 2 distantly related turtle hosts, M. subtrijuga and P. megacephalum, were genetically identical. Despite the fact that numerous Haemogregarina species of turtles have been described, the incompleteness of the morphological data and relatively low host specificity provides the space for large synonymy within this taxon. Therefore, a complex approach combining microscopic analyses together with molecular-genetic methods should represent the basic standard for all taxonomic studies.


Assuntos
Apicomplexa/classificação , Apicomplexa/citologia , Infecções Protozoárias em Animais/parasitologia , Animais , Ásia Sudeste , Filogenia , Infecções Protozoárias em Animais/epidemiologia , RNA de Protozoário/genética , RNA Ribossômico 18S/genética , Especificidade da Espécie , Tartarugas
11.
Rev Bras Parasitol Vet ; 23(1): 1-15, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24728354

RESUMO

The oocysts of the coccidia are robust structures, frequently isolated from the feces or urine of their hosts, which provide resistance to mechanical damage and allow the parasites to survive and remain infective for prolonged periods. The diagnosis of coccidiosis, species description and systematics, are all dependent upon characterization of the oocyst. Therefore, this review aimed to the provide a critical overview of the methodologies, advantages and limitations of the currently available morphological, morphometrical and molecular biology based approaches that may be utilized for characterization of these important structures. It has become apparent that no single methodology is sufficient to fully characterize these structures and the majority of researchers favor the use of combinational or polyphasic approaches.


Assuntos
Apicomplexa/citologia , Oocistos/citologia
12.
Rev. bras. parasitol. vet ; 23(1): 1-15, Jan-Mar/2014. tab, graf
Artigo em Inglês | LILACS | ID: lil-707194

RESUMO

The oocysts of the coccidia are robust structures, frequently isolated from the feces or urine of their hosts, which provide resistance to mechanical damage and allow the parasites to survive and remain infective for prolonged periods. The diagnosis of coccidiosis, species description and systematics, are all dependent upon characterization of the oocyst. Therefore, this review aimed to the provide a critical overview of the methodologies, advantages and limitations of the currently available morphological, morphometrical and molecular biology based approaches that may be utilized for characterization of these important structures. It has become apparent that no single methodology is sufficient to fully characterize these structures and the majority of researchers favor the use of combinational or polyphasic approaches.


Os oocistos de coccídios são estruturas robustas, frequentemente isoladas das fezes ou urina de seus hospedeiros, os quais oferecem resistência a danos mecânicos e permitem que os parasitas sobrevivam e permaneçam infecciosos por períodos prolongados. O diagnóstico da coccidiose, descrição das espécies e sistemática são dependentes da caracterização do oocisto. Portanto, esta revisão teve como objetivo fornecer uma visão crítica das metodologias, vantagens e limitações dos métodos morfológicos, morfométricos e moleculares que podem ser utilizados para a caracterização destas estruturas importantes. Tornou-se evidente que nenhuma metodologia única é suficiente para caracterizar completamente essas estruturas e que a maioria das pesquisas favorecem o uso de metodologias combinadas ou polifásicas.


Assuntos
Apicomplexa/citologia , Oocistos/citologia
13.
Nat Rev Microbiol ; 12(2): 125-36, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24384598

RESUMO

Toxoplasma gondii and Plasmodium falciparum are important human pathogens. These parasites and many of their apicomplexan relatives undergo a complex developmental process in the cells of their hosts, which includes genome replication, cell division and the assembly of new invasive stages. Apicomplexan cell cycle progression is both globally and locally regulated. Global regulation is carried out throughout the cytoplasm by diffusible factors that include cell cycle-specific kinases, cyclins and transcription factors. Local regulation acts on individual nuclei and daughter cells that are developing inside the mother cell. We propose that the centrosome is a master regulator that physically tethers cellular components and that provides spatial and temporal control of apicomplexan cell division.


Assuntos
Apicomplexa/fisiologia , Divisão Celular , Centrossomo/metabolismo , Infecções por Protozoários/parasitologia , Animais , Apicomplexa/citologia , Apicomplexa/genética , Núcleo Celular/metabolismo , Replicação do DNA , Humanos , Malária Falciparum/parasitologia , Modelos Biológicos , Plasmodium falciparum/citologia , Plasmodium falciparum/genética , Plasmodium falciparum/fisiologia , Proteínas de Protozoários/metabolismo , Toxoplasma/citologia , Toxoplasma/genética , Toxoplasma/fisiologia , Toxoplasmose/parasitologia
14.
Trends Parasitol ; 30(2): 58-64, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24411691

RESUMO

Apicomplexa are an ancient group of single-celled pathogens of humans and animals that include the etiological agents of such devastating plagues as malaria, toxoplasmosis, and coccidiosis. The defining feature of the Apicomplexa is the apical complex, the invasion machinery used to gain access to host cells. Evidence gathered from apicomplexans and their closest relatives argues that the apical complex is an extreme example of flagellum adaptability. The value of non-apicomplexan models, such as Chromera velia, is considered in an effort to understand the modern apical complex. The origin of the apical complex is unknown, but recent evidence points to a remarkable contribution from the flagellum to its evolution.


Assuntos
Apicomplexa/citologia , Apicomplexa/fisiologia , Animais , Evolução Biológica
15.
Int Rev Cell Mol Biol ; 306: 333-69, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24016529

RESUMO

Chromerida are algae possessing a complex plastid surrounded by four membranes. Although isolated originally from stony corals in Australia, they seem to be globally distributed. According to their molecular phylogeny, morphology, ultrastructure, structure of organellar genomes, and noncanonical pathway for tetrapyrrole synthesis, these algae are thought to be the closest known phototrophic relatives to apicomplexan parasites. Here, we summarize the current knowledge of cell biology and evolution of this novel group of algae, which contains only two formally described species, but is apparently highly diverse and virtually ubiquitous in marine environments.


Assuntos
Apicomplexa/metabolismo , Apicoplastos/parasitologia , Animais , Apicomplexa/citologia , Biologia Celular , Humanos
16.
J Eukaryot Microbiol ; 60(5): 514-25, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23879624

RESUMO

Selenidium is a genus of gregarine parasites that infect the intestines of marine invertebrates and have morphological, ecological, and motility traits inferred to reflect the early evolutionary history of apicomplexans. Because the overall diversity and phylogenetic position(s) of these species remain poorly understood, we performed a species discovery survey of Selenidium from tube-forming polychaetes. This survey uncovered five different morphotypes of trophozoites (feeding stages) living within the intestines of three different polychaete hosts. We acquired small subunit (SSU) rDNA sequences from single-cell (trophozoite) isolates, representing all five morphotypes that were also imaged with light and scanning electron microscopy. The combination of molecular, ecological, and morphological data provided evidence for four novel species of Selenidium, two of which were established in this study: Selenidium neosabellariae n. sp. and Selenidium sensimae n. sp. The trophozoites of these species differed from one another in the overall shape of the cell, the specific shape of the posterior end, the number and form of longitudinal striations, the presence/absence of transverse striations, and the position and shape of the nucleus. A fifth morphotype of Selenidium, isolated from the tube worm Dodecaceria concharum, was inferred to have been previously described as Selenidium cf. echinatum, based on general trophozoite morphology and host association. Phylogenetic analyses of the SSU rDNA sequences resulted in a robust clade of Selenidium species collected from tube-forming polychaetes, consisting of the two new species, the two additional morphotypes, S. cf. echinatum, and four previously described species (Selenidium serpulae, Selenidium boccardiellae, Selenidium idanthyrsae, and Selenidium cf. mesnili). Genetic distances between the SSU rDNA sequences in this clade distinguished closely related and potential cryptic species of Selenidium that were otherwise very similar in trophozoite morphology.


Assuntos
Apicomplexa/classificação , Apicomplexa/isolamento & purificação , Poliquetos/parasitologia , Animais , Apicomplexa/citologia , Apicomplexa/genética , Análise por Conglomerados , DNA de Protozoário/química , DNA de Protozoário/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Trato Gastrointestinal/parasitologia , Genes de RNAr , Microscopia , Dados de Sequência Molecular , Filogenia , RNA de Protozoário/genética , RNA Ribossômico 18S/genética , Análise de Sequência de DNA
17.
J Eukaryot Microbiol ; 60(2): 121-36, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23347320

RESUMO

Marine gregarines are poorly understood apicomplexan parasites with large trophozoites that inhabit the body cavities of marine invertebrates. Two novel species of gregarines were discovered in polychaete hosts collected in Canada and Japan. The trophozoites of Trichotokara japonica n. sp. were oval to rhomboidal shaped, and covered with longitudinal epicytic folds with a density of six to eight folds/micron. The nucleus was situated in the middle of the cell, and the mucron was elongated and covered with hair-like projections; antler-like projections also extended from the anterior tip of the mucron. The distinctively large trophozoites of Trichotokara eunicae n. sp. lacked an elongated mucron and had a tadpole-like cell shape consisting of a bulbous anterior region and a tapered tail-like posterior region. The cell surface was covered with longitudinal epicytic folds with a density of three to five folds/micron. Small subunit (SSU) rDNA sequences of both species were very divergent and formed a strongly supported clade with the recently described species Trichotokara nothriae and an environmental sequence (AB275074). This phylogenetic context combined with the morphological features of T. eunicae n. sp. required us to amend the description for Trichotokara. The sister clade to the Trichotokara clade consisted of environmental sequences and Lecudina polymorpha, which also possesses densely packed epicyctic folds (3-5 folds/micron) and a prominently elongated mucron. This improved morphological and molecular phylogenetic context justified the establishment of Paralecudina (ex. Lecudina) polymorpha n. gen. et comb.


Assuntos
Apicomplexa/classificação , Apicomplexa/isolamento & purificação , Poliquetos/parasitologia , Animais , Apicomplexa/citologia , Apicomplexa/genética , Canadá , Núcleo Celular/ultraestrutura , Análise por Conglomerados , DNA de Protozoário/química , DNA de Protozoário/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Genes de RNAr , Japão , Microscopia , Dados de Sequência Molecular , Organelas/ultraestrutura , Filogenia , RNA de Protozoário/genética , RNA Ribossômico 18S/genética , Análise de Sequência de DNA
18.
J Exp Biol ; 216(Pt 2): 230-5, 2013 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-22996442

RESUMO

Sexual reproduction of Ascogregarina taiwanensis (Apicomplexa: Lecudinidae), a parasite specific to the mosquito Aedes albopictus, in Malpighian tubules is initiated by the entry of the trophotozoites developed in the midgut shortly after pupation (usually <5 h). However, only a low proportion of trophozoites are able to migrate; others end up dying. In this study, we demonstrated that those trophozoites that failed to migrate eventually died of apoptosis. Morphological changes such as shrinkage, chromatin aggregations and formation of blunt ridges on the surface were seen in moribund trophozoites. In addition, DNA fragmentation of trophozoites isolated from the midgut of pupae was demonstrated by the presence of DNA ladders, Annexin V staining and TUNEL assays. Detection of caspase-like activity suggests that apoptosis of those trophozoites may have occurred through a mechanism of an intrinsic or mitochondrial-mediated pathway. Although apoptosis has been observed in various protozoan species, it is not clear how apoptosis in single-celled organisms might result from evolution by natural selection. However, we speculate that apoptosis may regulate the parasite load of A. taiwanensis within its natural mosquito host, leading to an optimized state of the survival rate for both parasite and host.


Assuntos
Aedes/parasitologia , Apicomplexa/fisiologia , Interações Hospedeiro-Parasita , Trofozoítos/citologia , Animais , Apicomplexa/citologia , Apoptose , Caspases/metabolismo , Movimento Celular , DNA de Protozoário/metabolismo , Marcação In Situ das Extremidades Cortadas , Infecções por Protozoários/parasitologia , Proteínas de Protozoários/metabolismo , Pupa/citologia , Pupa/fisiologia , Trofozoítos/fisiologia
19.
Folia Parasitol (Praha) ; 59(3): 167-72, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23136796

RESUMO

Records from a colubrid host are reported for Hepatozoon horridus, described originally from a viperid snake. Hepatozoon horridus in Pantherophis guttatus (Colubridae) has gamonts 14-18.0 by 4.0-5.5 microm, with length by width (LW) 60-99 microm2, and L/W ratio 2.5-3.9. Spherical to elongate, usually ovoid oocysts with L/W ratio 1.0-3.7 contain 16-160 spherical to usually ovoid sporocysts 15-31 by 14-26 microm, with L/W ratio 1.0-1.4, that contain 5-24 sporozoites. Two additional Hepatozoon species are described from ratsnakes in north Florida. Hepatozoon quadrivittata n. sp. from Pantherophis obsoletus quadrivittatus has gamonts 12-17 by 4-6 microm, LW 56-102 microm2, and L/W ratio 2.6-3.8. Nearly spherical oocysts with L/W 1.0-1.1 contain 5-227 spherical to slightly ovoid sporocysts 20-48 by 19-45 microm, with L/W ratio 1.0-1.4, that contain 13-48 sporozoites. Hepatozoon spiloides n. sp. from Pantherophis obsoletus spiloides forms gamonts 12-15 by 4-5 microm with LW 48-75 microm2 and L/W ratio 2.6-3.5. Occasionally rounded but usually elongate oocysts, with L/W ratio 1.0-2.7, contain 5-21 spherical to elongate sporocysts 28-43 by 18-35 microm, L/W ratio 2.5-3.9. In the distinctive Hepatozoon sp. present in Pantherophis obsoletus spiloides, gamonts are 13-17 by 5-10 microm, with LW 75-140 microm2 and L/W ratio 1.4-3.0. Infected erythrocytes are always distorted and enlarged on average 2.5 times the size of uninfected cells, with nuclei enlarged by one-third and broadly elongated. Gamonts often stained deep blue, and cytoplasm of erythrocytes infected with mature gamonts was always dehemoglobinized. Sporogony could not be obtained in three feedings by hundreds of Aedes aegypti, which usually died within the first 24-48 hr.


Assuntos
Apicomplexa/classificação , Apicomplexa/isolamento & purificação , Infecções Protozoárias em Animais/parasitologia , Serpentes/parasitologia , Animais , Apicomplexa/citologia , Florida/epidemiologia , Infecções Protozoárias em Animais/epidemiologia
20.
Int J Parasitol ; 42(12): 1071-81, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23068912

RESUMO

The alveolate superphylum includes many free-living and parasitic organisms, which are united by the presence of alveolar sacs lying proximal to the plasma membrane, providing cell structure. All species comprising the apicomplexan group of alveolates are parasites and have adapted to the unique requirements of the parasitic lifestyle. Here the evolution of apicomplexan secretory organelles that are involved in the critical process of egress from one cell and invasion of another is explored. The variations within the Apicomplexa and how these relate to species-specific biology will be discussed. In addition, recent studies have identified specific calcium-sensitive molecules that coordinate the various events and regulate the release of these secretory organelles within apicomplexan parasites. Some aspects of this machinery are conserved outside the Apicomplexa, and are beginning to elucidate the conserved nature of the machinery. Briefly, the relationship of this secretion machinery within the Apicomplexa will be discussed, compared with free-living and predatory alveolates, and how these might have evolved from a common ancestor.


Assuntos
Apicomplexa/citologia , Apicomplexa/fisiologia , Organelas/fisiologia , Animais , Apicomplexa/genética , Evolução Biológica , Regulação da Expressão Gênica/fisiologia , Infecções por Protozoários/parasitologia
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