Biochemical evidence for the existence of thymidylate synthase in the obligate intracellular parasite Chlamydia trachomatis.

Since eucaryotic cell-derived thymidine or thymidine nucleotides are not incorporated into Chlamydia trachomatis DNA, we hypothesized that C. trachomatis must obtain dTTP for DNA synthesis by converting dUMP to dTMP. In most cells, this reaction is catalyzed by thymidylate synthase (TS) and requires 5,10-methylenetetrahydrofolate as a cofactor. We used C. trachomatis serovar L2 and a mutant CHO K1 cell line with a genetic deficiency in folate metabolism as a host for chlamydial growth. This cell line lacks a functional dihydrofolate reductase (DHFR) gene and, as a result, is unable to carry out de novo synthesis of dTTP. C. trachomatis inclusions form normally when DHFR- cells are starved for thymidine 24 h prior to and during the course of infection. When [6-3H]uridine is used as a precursor to label C. trachomatis-infected CHO DHFR- cells, radiolabel is readily incorporated into chlamydia-specific DNA. When DNA from [6-3H]uridine-labelled infected cultures is acid hydrolyzed and subjected to high-performance liquid chromatography analysis, radiolabel is detected in thymine and cytosine nucleobases. By using the DHFR- cell line as a host and [5-3H]uridine as a precursor, we could monitor intracellular C. trachomatis TS activity simply by following the formation of tritiated water. There is a good correlation between in situ TS activity and DNA synthesis activity during the chlamydial growth cycle. In addition, both C. trachomatis-specific DNA synthesis and 3H2O release are inhibited by exogenously added 5-fluorouridine but not by 5-fluorodeoxyuridine. Finally, we demonstrated in vitro TS activity in crude extracts prepared from highly purified C. trachomatis reticulate bodies. The activity is dependent on the presence of methylenetetrahydrofolic acid and can be inhibited with 5-fluoro-dUMP. Taken together, these results indicate that C. trachomatis contains a TS for the synthesis of dTMP.     

Apoptotic mimicry by an obligate intracellular parasite downregulates macrophage microbicidal activity.

Programmed cell death by apoptosis of unnecessary or potentially harmful cells is clearly beneficial to multicellular organisms. Proper functioning of such a program demands that the removal of dying cells proceed without an inflammatory reaction. Phosphatidylserine (PS) is one of the ligands displayed by apoptotic cells that participates in their noninflammatory removal when recognized by neighboring phagocytes. PS ligation induces the release of transforming growth factor-beta (TGF-beta), an antiinflammatory cytokine that mediates the suppression of macrophage-mediated inflammation. In Hydra vulgaris, an organism that stands at the base of metazoan evolution, the selective advantage provided by apoptosis lies in the fact that Hydra can survive recycling apoptotic cells by phagocytosis. In unicellular organisms, it has been proposed that altruistic death benefits clonal populations of yeasts and trypanosomatids. Now we show that advantageous features of the apoptotic process can operate without death as the necessary outcome. Leishmania spp are able to evade the killing activity of phagocytes and establish themselves as obligate intracellular parasites. Amastigotes, responsible for disease propagation, similar to apoptotic cells, inhibit macrophage activity by exposing PS. Exposed PS participates in amastigote internalization. Recognition of this moiety by macrophages induces TGF-beta secretion and IL-10 synthesis, inhibits NO production, and increases susceptibility to intracellular leishmanial growth.     

Entomophthora pyriformis,sp. n., entomophthorale parasite de puceron

Summary A new species ofEntomophthora found in France on Aphids is described as new under the nameE, pyriformis. It is distinguished by the following characters: multinucleate, pear-shaped conidia, with large papilla; small resting spores; short, more or less branched hyphal bodies. A key of determination is given for the Aphid parasiteEntomophthora species with more or less spherical conidia.      

Haycocknema perplexum n. g., n. sp. (Nematoda: Robertdollfusidae): an intramyofibre parasite in man

Haycocknema perplexum n. g., n. sp. (Nematoda: Robertdollfusidae) is described from a man in Tasmania, Australia. Adult male and female nematodes and larvae were recovered from myofibres following biopsy of the right vastus lateralis muscle and were associated with a polymyositis. H. perplexum is distinguished from all other genera of the Muspiceoidea by the presence of a large amorphous cell supporting a granule-filled, flask- or gourd-shaped reservoir in the rectal region of mature and gravid female nematodes, often containing one or more large, refractile, thick-rimmed globules on the external surface of the reservoir, by the small number of ova/eggs/larvae developing in each uterus, by the minute, weakly-sclerotised, almost tubular spicule, by the presence of a pair of ampulla-shaped glands posteriorly and by the presence of lateral bacillary bands comprised of a single row of pore cells spaced irregularly and extending posteriorly to the region of the vulva in immature females.     

Studies on Porochlamydia buthi g. n., sp. n., an intracellular pathogen of the scorpion Buthus occitanus

An endemic disease caused by an intracellular microorganism related to the Chlamydiales, Porochlamydia buthi g. n., sp. n., exists in populations of the scorpion Buthus occitanus of Languedoc in southern France. The pathogen's developmental cycle occurs in the hepatopancreatic cells and progressively brings about the destruction of this organ. The microorganism is spread mostly through dejecta which contain the infectious forms during nearly the entire period of illness.     

Pleistophora finisterrensis n. sp., a microsporidian parasite of blue whiting Micromesistius poutassou

Pleistophora finisterrensis n. sp. is a microsporidian parasite of the hypoaxial musculature of the blue whiting Micromesistius poutassou (Risso). Foci of infection are between 3 and 6 mm in length and have no evident effects on adjacent muscle fibres. We found only a single type of spore (uninucleate, with mean dimensions of 4×2 µm in fresh preparations), contained within sporophorous vesicles (mean diameter 19 µm in fresh preparations; 150–250 spores per vesicle). All of the development stages of this microsporidian are monokaryotic. The meronts are initially uninucleate and bounded by a plasmalemma. Towards the end of merogony, meronts are multinucleate plasmodia with a well-defined surface coat. Sporogony is polysporous, with multinucleate sporonts, which likewise have a well-defined surface coat (about 130 nm thick), dividing by plasmotomy to give rise to uninucleate sporoblasts. The polar tube is isofilar and consists of 8–9 turns in the posterior half of spore. The polaroplast is made up of an anterior lamellar part and a posterior vesicular part.     

Furcohaptor cynoglossi n. g., n. sp., an ancyrocephaline monogenean gill parasite with a bifurcate haptor and a note on its adhesive attitude

An ancyrocephaline monogenean,Furcohaptor cynoglossi n. g., n. sp., is described from the gills of the marine teleost flatfishCynoglossus macrostomus caught off the coast of Kerala State in India. The parasite is also recorded onC. puncticeps. The haptor divides to form two elongated and slender haptoral arms, each bearing at the distal end a cluster of relatively small sclerites, comprising the following: two hamuli, one of which is rod-shaped and the other of typical hooked shape; a bar articulating with the typical hamulus; five marginal hooklets of typical shape, each with a domus; a sixth marginal hooklet which is shorter and more slender than the others and lacks a domus. This sixth marginal hooklet is hard to locate in some individuals. The haptoral arms embrace a primary gill lamella, their distal hook-bearing regions meeting or overlapping on the side of the lamella opposite to the parasite's body. Species of the genusBifurcohaptor Jain, 1958 differ in that two of the hamuli are greatly enlarged and support the haptoral arms.     

Retroporomonorchis pansho n. g., n. sp., an unusual monorchiid trematode exploiting an atypical host

Systematic Parasitology - The Monorchiidae Odhner, 1911 are well represented in tropical and subtropical marine fishes worldwide but rarely reported from the Lutjanidae, an important family of...     

Adelphamoeba galeacystis n. g., n. sp., an Amoeboflagellate Isolated from Soil*

SYNOPSIS. An amoeboflagellate isolated from common soil is described. The amoeboid stage is typically limax and contains a well differentiated uroid region. The flagellate has 2 flagella, which emerge anteriorly and are equal in length. It has a ventral cytostome near the anterior border. The cyst is helmet-shaped and without opercula. Polar masses are present during nuclear division.     

Description of Perkinsus beihaiensis n. sp., a new Perkinsus sp. parasite in oysters of Southern China

Oysters were collected from coastal locations in China from 1999-2006 for parasite analyses by molecular, culture, and histological techniques. Polymerase chain reaction-based assays targeting the internal transcribed spacer (ITS) region of the ribosomal RNA gene complex were performed to detect the presence of Perkinsus species. Sequencing and phylogenetic analysis of amplified Perkinsus sp. DNAs indicated that a novel Perkinsus sp. infects Crassostrea hongkongensis, Crassostrea ariakensis, and other bivalve hosts from Fujian to Guangxi provinces in southern China. Prevalence of this Perkinsus sp. reaches as high as 60% in affected oyster populations. Analyses of nucleotide sequences of the rRNA ITS region and of large subunit rRNA and actin genes, consistently confirmed the genus affiliation of this Perkinsus sp., but distinguished it from currently accepted Perkinsus species. Parasite cell types, such as signet ring trophozoites of 2-8 microm diameter, were observed by histology, and application of both genus Perkinsus and Perkinsus species-specific in situ hybridization probes consistently labelled the same Perkinsus sp. cells in histological sections from infected oyster tissues. Combined phylogenetic and histological results support the identity of a new parasite species, Perkinsus beihaiensis n. sp.     

Luteimonas dalianensis sp. nov., an obligate marine bacterium isolated from seawater

A marine bacterial strain, designated OB44-3^T, was isolated from a crude oil-contaminated seawater sample collected near Dalian Bay, China. Cells of strain OB44-3^T were Gramnegative, aerobic, rod-shaped, and oxidase- and catalasepositive. The major fatty acids were branched-chain saturated iso-C_15:0 (27.9%) and unsaturated iso-C_17:1 ω9c (14.8%). The DNA G+C content was 64.6 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain OB44-3^T was a member of the genus Luteimonas (95–96% 16S rRNA gene sequence similarity); its closest neighbors were the type strains of Luteimonas terricola (96% sequence similarity), Luteimonas mephitis (96%), and Luteimonas lutimaris (96%). On the basis of phenotypic, chemotaxonomic, and phylogenetic distinctiveness, strain OB44-3^T was considered to represent a novel species of the genus Luteimonas. The name Luteimonas dalianensis sp. nov. is proposed, with strain OB44-3^T (=CGMCC 1.12191^T =JCM 18136^T) as the type strain.     

Revision of the family Duboscquellidae with description of Euduboscquella crenulata n. gen., n. sp. (Dinoflagellata, Syndinea), an intracellular parasite of the ciliate Favella panamensis Kofoid & Campbell

Recent recognition that tintinnids are infected by dinophycean as well as syndinean parasites prompts taxonomic revision of dinoflagellate species that parasitize these ciliates. Long overlooked features of the type species Duboscquella tintinnicola are used to emend the genus and family Duboscquellidae, resulting in both taxa being moved from the Syndinea to the Dinophyceae. Syndinean species previously classified as Duboscquella are relocated to Euduboscquella n. gen., with Euduboscquella crenulata n. sp. as the type. As an endoparasitic species, E. crenulata shares with its congeners processes associated with intracellular development and sporogenesis, but differs from closely related species in nuclear and cortical morphology of the trophont, including a distinctively grooved shield (= episome) that imparts a crenulated appearance in optical section. In addition, E. crenulata produces three morphologically distinct spore types, two of which undergo syngamy to form a uninucleate zygote. The zygote undergoes successive division to produce four daughter cells of unequal size, but that resemble the nonmating spore type.     

Erhardorina n. g., Ascogregarina polynesiensis n. sp., Eimeria golemanskii n. sp., Isospora tamariscini n. sp., Gregarina kazumii n. nom., new combinations and emendations in the names of apicomplexan protozoa

On the basis of a review of the approximately 4300 species of apicomplexan protozoa, the following new species, new names, new combinations, and emendations are given: NEW GENUS, Erhardovina; NEW SPECIES, Ascogregarina polynesiensis, Eimeria golemanskii, Isospora tamariscini; NEW NAME, Gregarina kazumii; NEW COMBINATIONS, Ascogregarina brachyceri (Purrini, 1980), Erhardovina euzeti (Lipa, 1981), E. scutovertexi (Erhardová, 1955), Haemorhormidium batrachi (Chaudhuri & Choudhury, 1983); EMENDATIONS, Selenidium francianum (Arvy, 1952) Tuzet & Ormières, 1965, Pyxinioides bolitoides D. P. Henry, 1938, P. japonicus H. Hoshide, 1951, P. kamenote H. Hoshide, 1951, P. kurofuji H. Hoshide, 1951, P. oshoroensis H. Hoshide, 1951, P. pugetensis D. P. Henry, 1938, Gregarina levinei Haldar & Sarkar, 1980, Retractocephalus halticae Haldar, Chakraborty & Kundu, 1982, Cnemidospora schizophylli Tuzet & Guerin, 1947, Grebneckiella indica (Merton, 1911) Watson, 1916, Quadruspinospora atractomorphae Haldar & Chakraborty, 1978, Haemogregarina acipenseri Nawrotzky, 1914, H. lobianci Yakimov & Kohl-Yakimov, 1912, H. yakimovikohlae Wladimiroff, 1910, Hepatozoon luehi (Sambon, 1909) Pessoa, Cavalheiro & de Souza, 1970, Eimeria beyerae Ovezmukhammedov, 1977, E. (?) gigantea (Labbé, 1896) Reichenow, 1921, E. (?) labbei Hardcastle, 1943, E. rufi Prasad, 1960, E. (?) scylii (Drago, 1902) Levine & Becker, 1933, Isospora corvi Ray, Shivnani, Oommen & Bhaskaran, 1952, I. melopsittaci Bhatia, Chauhan, Arora & Agrawal, 1973, I. seicerci Ray, Shivnani, Oommen & Bhaskaran, 1952, I. stomatici Chakravarty & Kar, 1944, I. triffitae Nukerbaeva & Svanbaev, 1973, Wenyonella mackinnonae Misra, 1947, Octosporella sanguinolentae Ovezmukhammedov, 1975, Lankesterella millani Alvarez Calvo, 1975, Sarcocystis woodhousei Dogel', 1916, Haemoproteus lari Yakunin, 1972, Babesia ninakohlyakimovae (Yakimoff & Shokhor, 1916), Theileria ninakohlyakimovae (Yakimov, 1916) Krylov, 1974, Haemohormidium batrachi (Chaudhuri & Choudhury, 1983).