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Sample records for suppressive eukaryotic parasites

  1. Patterns of prokaryotic lateral gene transfers affecting parasitic microbial eukaryotes

    DEFF Research Database (Denmark)

    Alsmark, Cecilia; Foster, Peter G; Sicheritz-Pontén, Thomas

    2013-01-01

    BACKGROUND: The influence of lateral gene transfer on gene origins and biology in eukaryotes is poorly understood compared with those of prokaryotes. A number of independent investigations focusing on specific genes, individual genomes, or specific functional categories from various eukaryotes have...... approach to systematically investigate lateral gene transfer affecting the proteomes of thirteen, mainly parasitic, microbial eukaryotes, representing four of the six eukaryotic super-groups. All of the genomes investigated have been significantly affected by prokaryote-to-eukaryote lateral gene transfers...... indicated that lateral gene transfer does indeed affect eukaryotic genomes. However, the lack of common methodology and criteria in these studies makes it difficult to assess the general importance and influence of lateral gene transfer on eukaryotic genome evolution. RESULTS: We used a phylogenomic...

  2. In silico ionomics segregates parasitic from free-living eukaryotes.

    Science.gov (United States)

    Greganova, Eva; Steinmann, Michael; Mäser, Pascal; Fankhauser, Niklaus

    2013-01-01

    Ion transporters are fundamental to life. Due to their ancient origin and conservation in sequence, ion transporters are also particularly well suited for comparative genomics of distantly related species. Here, we perform genome-wide ion transporter profiling as a basis for comparative genomics of eukaryotes. From a given predicted proteome, we identify all bona fide ion channels, ion porters, and ion pumps. Concentrating on unicellular eukaryotes (n = 37), we demonstrate that clustering of species according to their repertoire of ion transporters segregates obligate endoparasites (n = 23) on the one hand, from free-living species and facultative parasites (n = 14) on the other hand. This surprising finding indicates strong convergent evolution of the parasites regarding the acquisition and homeostasis of inorganic ions. Random forest classification identifies transporters of ammonia, plus transporters of iron and other transition metals, as the most informative for distinguishing the obligate parasites. Thus, in silico ionomics further underscores the importance of iron in infection biology and suggests access to host sources of nitrogen and transition metals to be selective forces in the evolution of parasitism. This finding is in agreement with the phenomenon of iron withholding as a primordial antimicrobial strategy of infected mammals.

  3. Convergent use of RhoGAP toxins by eukaryotic parasites and bacterial pathogens.

    Directory of Open Access Journals (Sweden)

    Dominique Colinet

    2007-12-01

    Full Text Available Inactivation of host Rho GTPases is a widespread strategy employed by bacterial pathogens to manipulate mammalian cellular functions and avoid immune defenses. Some bacterial toxins mimic eukaryotic Rho GTPase-activating proteins (GAPs to inactivate mammalian GTPases, probably as a result of evolutionary convergence. An intriguing question remains whether eukaryotic pathogens or parasites may use endogenous GAPs as immune-suppressive toxins to target the same key genes as bacterial pathogens. Interestingly, a RhoGAP domain-containing protein, LbGAP, was recently characterized from the parasitoid wasp Leptopilina boulardi, and shown to protect parasitoid eggs from the immune response of Drosophila host larvae. We demonstrate here that LbGAP has structural characteristics of eukaryotic RhoGAPs but that it acts similarly to bacterial RhoGAP toxins in mammals. First, we show by immunocytochemistry that LbGAP enters Drosophila immune cells, plasmatocytes and lamellocytes, and that morphological changes in lamellocytes are correlated with the quantity of LbGAP they contain. Demonstration that LbGAP displays a GAP activity and specifically interacts with the active, GTP-bound form of the two Drosophila Rho GTPases Rac1 and Rac2, both required for successful encapsulation of Leptopilina eggs, was then achieved using biochemical tests, yeast two-hybrid analysis, and GST pull-down assays. In addition, we show that the overall structure of LbGAP is similar to that of eukaryotic RhoGAP domains, and we identify distinct residues involved in its interaction with Rac GTPases. Altogether, these results show that eukaryotic parasites can use endogenous RhoGAPs as virulence factors and that despite their differences in sequence and structure, eukaryotic and bacterial RhoGAP toxins are similarly used to target the same immune pathways in insects and mammals.

  4. Unexpected Importance of Potential Parasites in the Composition of the Freshwater Small-Eukaryote Community▿

    Science.gov (United States)

    Lepère, Cécile; Domaizon, Isabelle; Debroas, Didier

    2008-01-01

    The diversity of small eukaryotes (0.2 to 5 μm) in a mesotrophic lake (Lake Bourget) was investigated using 18S rRNA gene library construction and fluorescent in situ hybridization coupled with tyramide signal amplification (TSA-FISH). Samples collected from the epilimnion on two dates were used to extend a data set previously obtained using similar approaches for lakes with a range of trophic types. A high level of diversity was recorded for this system with intermediate trophic status, and the main sequences from Lake Bourget were affiliated with ciliates (maximum, 19% of the operational taxonomic units [OTUs]), cryptophytes (33%), stramenopiles (13.2%), and cercozoa (9%). Although the comparison of TSA-FISH results and clone libraries suggested that the level of Chlorophyceae may have been underestimated using PCR with 18S rRNA primers, heterotrophic organisms dominated the small-eukaryote assemblage. We found that a large fraction of the sequences belonged to potential parasites of freshwater phytoplankton, including sequences affiliated with fungi and Perkinsozoa. On average, these sequences represented 30% of the OTUs (40% of the clones) obtained for each of two dates for Lake Bourget. Our results provide information on lacustrine small-eukaryote diversity and structure, adding to the phylogenetic data available for lakes with various trophic types. PMID:18359836

  5. Wholly Rickettsia! Reconstructed Metabolic Profile of the Quintessential Bacterial Parasite of Eukaryotic Cells.

    Science.gov (United States)

    Driscoll, Timothy P; Verhoeve, Victoria I; Guillotte, Mark L; Lehman, Stephanie S; Rennoll, Sherri A; Beier-Sexton, Magda; Rahman, M Sayeedur; Azad, Abdu F; Gillespie, Joseph J

    2017-09-26

    Reductive genome evolution has purged many metabolic pathways from obligate intracellular Rickettsia ( Alphaproteobacteria ; Rickettsiaceae ). While some aspects of host-dependent rickettsial metabolism have been characterized, the array of host-acquired metabolites and their cognate transporters remains unknown. This dearth of information has thwarted efforts to obtain an axenic Rickettsia culture, a major impediment to conventional genetic approaches. Using phylogenomics and computational pathway analysis, we reconstructed the Rickettsia metabolic and transport network, identifying 51 host-acquired metabolites (only 21 previously characterized) needed to compensate for degraded biosynthesis pathways. In the absence of glycolysis and the pentose phosphate pathway, cell envelope glycoconjugates are synthesized from three imported host sugars, with a range of additional host-acquired metabolites fueling the tricarboxylic acid cycle. Fatty acid and glycerophospholipid pathways also initiate from host precursors, and import of both isoprenes and terpenoids is required for the synthesis of ubiquinone and the lipid carrier of lipid I and O-antigen. Unlike metabolite-provisioning bacterial symbionts of arthropods, rickettsiae cannot synthesize B vitamins or most other cofactors, accentuating their parasitic nature. Six biosynthesis pathways contain holes (missing enzymes); similar patterns in taxonomically diverse bacteria suggest alternative enzymes that await discovery. A paucity of characterized and predicted transporters emphasizes the knowledge gap concerning how rickettsiae import host metabolites, some of which are large and not known to be transported by bacteria. Collectively, our reconstructed metabolic network offers clues to how rickettsiae hijack host metabolic pathways. This blueprint for growth determinants is an important step toward the design of axenic media to rescue rickettsiae from the eukaryotic cell. IMPORTANCE A hallmark of obligate intracellular

  6. Reconstitution of a eukaryotic replisome reveals suppression mechanisms that define leading/lagging strand operation

    Science.gov (United States)

    Georgescu, Roxana E; Schauer, Grant D; Yao, Nina Y; Langston, Lance D; Yurieva, Olga; Zhang, Dan; Finkelstein, Jeff; O'Donnell, Mike E

    2015-01-01

    We have reconstituted a eukaryotic leading/lagging strand replisome comprising 31 distinct polypeptides. This study identifies a process unprecedented in bacterial replisomes. While bacteria and phage simply recruit polymerases to the fork, we find that suppression mechanisms are used to position the distinct eukaryotic polymerases on their respective strands. Hence, Pol ε is active with CMG on the leading strand, but it is unable to function on the lagging strand, even when Pol δ is not present. Conversely, Pol δ-PCNA is the only enzyme capable of extending Okazaki fragments in the presence of Pols ε and α. We have shown earlier that Pol δ-PCNA is suppressed on the leading strand with CMG (Georgescu et al., 2014). We propose that CMG, the 11-subunit helicase, is responsible for one or both of these suppression mechanisms that spatially control polymerase occupancy at the fork. DOI: http://dx.doi.org/10.7554/eLife.04988.001 PMID:25871847

  7. Leishmania eukaryotic initiation factor (LeIF inhibits parasite growth in murine macrophages.

    Directory of Open Access Journals (Sweden)

    Olga Koutsoni

    Full Text Available The leishmaniases constitute neglected global public health problems that require adequate control measures, prophylactic clinical vaccines and effective and non-toxic drug treatments. In this study, we explored the potential of Leishmania infantum eukaryotic initiation factor (LieIF, an exosomal protein, as a novel anti-infective therapeutic molecule. More specifically, we assessed the efficacy of recombinant LieIF, in combination with recombinant IFN-γ, in eliminating intracellular L. donovani parasites in an in vitro macrophage model. J774A.1 macrophages were initially treated with LieIF/IFN-γ prior to in vitro infection with L. donovani stationary phase promastigotes (pre-infection treatment, and resistance to infection was observed 72 h after infection. J774A.1 macrophages were also treated with LieIF/IFN-γ after L. donovani infection (post-infection treatment, and resistance to infection was also observed at both time points tested (19 h and 72 h after infection. To elucidate the LieIF/IFN-γ-induced mechanism(s that mediate the reduction of intracellular parasite growth, we examined the generation of potent microbicidal molecules, such as nitric oxide (NO and reactive oxygen species (ROS, within infected macrophages. Furthermore, macrophages pre-treated with LieIF/IFN-γ showed a clear up-regulation in macrophage inflammatory protein 1α (MIP-1α as well as tumor necrosis factor alpha (TNF-α expression. However, significant different protein levels were not detected. In addition, macrophages pre-treated with LieIF/IFN-γ combined with anti-TNF-α monoclonal antibody produced significantly lower amounts of ROS. These data suggest that during the pre-treatment state, LieIF induces intramacrophage parasite growth inhibition through the production of TNF-α, which induces microbicidal activity by stimulating NO and ROS production. The mechanisms of NO and ROS production when macrophages are treated with LieIF after infection are probably

  8. The cauliflower Orange gene enhances petiole elongation by suppressing expression of eukaryotic release factor 1.

    Science.gov (United States)

    Zhou, Xiangjun; Sun, Tian-Hu; Wang, Ning; Ling, Hong-Qing; Lu, Shan; Li, Li

    2011-04-01

    The cauliflower (Brassica oleracea var. botrytis) Orange (Or) gene affects plant growth and development in addition to conferring β-carotene accumulation. This study was undertaken to investigate the molecular basis for the effects of the Or gene mutation in on plant growth. The OR protein was found to interact with cauliflower and Arabidopsis eukaryotic release factor 1-2 (eRF1-2), a member of the eRF1 family, by yeast two-hybrid analysis and by bimolecular fluorescence complementation (BiFC) assay. Concomitantly, the Or mutant showed reduced expression of the BoeRF1 family genes. Transgenic cauliflower plants with suppressed expression of BoeRF1-2 and BoeRF1-3 were generated by RNA interference. Like the Or mutant, the BoeRF1 RNAi lines showed increased elongation of the leaf petiole. This long-petiole phenotype was largely caused by enhanced cell elongation, which resulted from increased cell length and elevated expression of genes involved in cell-wall loosening. These findings demonstrate that the cauliflower Or gene controls petiole elongation by suppressing the expression of eRF1 genes, and provide new insights into the molecular mechanism of leaf petiole regulation. © 2010 The Authors. New Phytologist © 2010 New Phytologist Trust.

  9. Current Perspectives of Telomerase Structure and Function in Eukaryotes with Emerging Views on Telomerase in Human Parasites.

    Science.gov (United States)

    Dey, Abhishek; Chakrabarti, Kausik

    2018-01-24

    Replicative capacity of a cell is strongly correlated with telomere length regulation. Aberrant lengthening or reduction in the length of telomeres can lead to health anomalies, such as cancer or premature aging. Telomerase is a master regulator for maintaining replicative potential in most eukaryotic cells. It does so by controlling telomere length at chromosome ends. Akin to cancer cells, most single-cell eukaryotic pathogens are highly proliferative and require persistent telomerase activity to maintain constant length of telomere and propagation within their host. Although telomerase is key to unlimited cellular proliferation in both cases, not much was known about the role of telomerase in human parasites (malaria, Trypanosoma , etc.) until recently. Since telomerase regulation is mediated via its own structural components, interactions with catalytic reverse transcriptase and several factors that can recruit and assemble telomerase to telomeres in a cell cycle-dependent manner, we compare and discuss here recent findings in telomerase biology in cancer, aging and parasitic diseases to give a broader perspective of telomerase function in human diseases.

  10. Unbiased RNA Shotgun Metagenomics in Social and Solitary Wild Bees Detects Associations with Eukaryote Parasites and New Viruses.

    Directory of Open Access Journals (Sweden)

    Karel Schoonvaere

    Full Text Available The diversity of eukaryote organisms and viruses associated with wild bees remains poorly characterized in contrast to the well-documented pathosphere of the western honey bee, Apis mellifera. Using a deliberate RNA shotgun metagenomic sequencing strategy in combination with a dedicated bioinformatics workflow, we identified the (micro-organisms and viruses associated with two bumble bee hosts, Bombus terrestris and Bombus pascuorum, and two solitary bee hosts, Osmia cornuta and Andrena vaga. Ion Torrent semiconductor sequencing generated approximately 3.8 million high quality reads. The most significant eukaryote associations were two protozoan, Apicystis bombi and Crithidia bombi, and one nematode parasite Sphaerularia bombi in bumble bees. The trypanosome protozoan C. bombi was also found in the solitary bee O. cornuta. Next to the identification of three honey bee viruses Black queen cell virus, Sacbrood virus and Varroa destructor virus-1 and four plant viruses, we describe two novel RNA viruses Scaldis River bee virus (SRBV and Ganda bee virus (GABV based on their partial genomic sequences. The novel viruses belong to the class of negative-sense RNA viruses, SRBV is related to the order Mononegavirales whereas GABV is related to the family Bunyaviridae. The potential biological role of both viruses in bees is discussed in the context of recent advances in the field of arthropod viruses. Further, fragmentary sequence evidence for other undescribed viruses is presented, among which a nudivirus in O. cornuta and an unclassified virus related to Chronic bee paralysis virus in B. terrestris. Our findings extend the current knowledge of wild bee parasites in general and addsto the growing evidence of unexplored arthropod viruses in valuable insects.

  11. Unbiased RNA Shotgun Metagenomics in Social and Solitary Wild Bees Detects Associations with Eukaryote Parasites and New Viruses.

    Science.gov (United States)

    Schoonvaere, Karel; De Smet, Lina; Smagghe, Guy; Vierstraete, Andy; Braeckman, Bart P; de Graaf, Dirk C

    2016-01-01

    The diversity of eukaryote organisms and viruses associated with wild bees remains poorly characterized in contrast to the well-documented pathosphere of the western honey bee, Apis mellifera. Using a deliberate RNA shotgun metagenomic sequencing strategy in combination with a dedicated bioinformatics workflow, we identified the (micro-)organisms and viruses associated with two bumble bee hosts, Bombus terrestris and Bombus pascuorum, and two solitary bee hosts, Osmia cornuta and Andrena vaga. Ion Torrent semiconductor sequencing generated approximately 3.8 million high quality reads. The most significant eukaryote associations were two protozoan, Apicystis bombi and Crithidia bombi, and one nematode parasite Sphaerularia bombi in bumble bees. The trypanosome protozoan C. bombi was also found in the solitary bee O. cornuta. Next to the identification of three honey bee viruses Black queen cell virus, Sacbrood virus and Varroa destructor virus-1 and four plant viruses, we describe two novel RNA viruses Scaldis River bee virus (SRBV) and Ganda bee virus (GABV) based on their partial genomic sequences. The novel viruses belong to the class of negative-sense RNA viruses, SRBV is related to the order Mononegavirales whereas GABV is related to the family Bunyaviridae. The potential biological role of both viruses in bees is discussed in the context of recent advances in the field of arthropod viruses. Further, fragmentary sequence evidence for other undescribed viruses is presented, among which a nudivirus in O. cornuta and an unclassified virus related to Chronic bee paralysis virus in B. terrestris. Our findings extend the current knowledge of wild bee parasites in general and addsto the growing evidence of unexplored arthropod viruses in valuable insects.

  12. The Eukaryotic Pathogen Databases: a functional genomic resource integrating data from human and veterinary parasites.

    Science.gov (United States)

    Harb, Omar S; Roos, David S

    2015-01-01

    Over the past 20 years, advances in high-throughput biological techniques and the availability of computational resources including fast Internet access have resulted in an explosion of large genome-scale data sets "big data." While such data are readily available for download and personal use and analysis from a variety of repositories, often such analysis requires access to seldom-available computational skills. As a result a number of databases have emerged to provide scientists with online tools enabling the interrogation of data without the need for sophisticated computational skills beyond basic knowledge of Internet browser utility. This chapter focuses on the Eukaryotic Pathogen Databases (EuPathDB: http://eupathdb.org) Bioinformatic Resource Center (BRC) and illustrates some of the available tools and methods.

  13. Experimental study on parasitic mode suppression using FeSiAl in relativistic klystron amplifier

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zehai [College of Basic Education, National University of Defense Technology, Changsha, Hunan 410072 (China)

    2015-03-15

    Experimental study of parasitic mode suppression using electromagnetic attenuate material FeSiAl in an S-band Relativistic Klystron Amplifier (RKA) is presented in this paper. The FeSiAl powder is coated and sintered onto the inner surface of a drift tube which locates between the input and the middle cavity of the RKA. Cold tests show that the attenuate rate of the tube against parasitic mode TE{sub 11} is about 50%. Experiments carried out on the Torch-01 accelerator present that the tube is effective in suppressing the parasitic mode. Two typical outputs are obtained. When the diode voltage is on a moderate level, the RKA operates well and the parasitic mode is totally suppressed. The pulse length of the High Power Microwave (HPM) almost equals the electron beam pulse length and the HPM average output power is about 300 MW, with a power efficiency of 10%. When the diode voltage is on a higher level, the output power and efficiency rise but the parasitic mode oscillation occurred and the pulse length is shortened. By contrast, the parasitic mode oscillation is too strong for the RKA to operate normally with un-sintered drift tube. The experimental study implies that FeSiAl is effective in suppressing the parasitic mode oscillation in a certain extent. However, total suppression needs a deeper attenuate rate and further investigation.

  14. Experimental study on parasitic mode suppression using FeSiAl in relativistic klystron amplifier

    Science.gov (United States)

    Zhang, Zehai

    2015-03-01

    Experimental study of parasitic mode suppression using electromagnetic attenuate material FeSiAl in an S-band Relativistic Klystron Amplifier (RKA) is presented in this paper. The FeSiAl powder is coated and sintered onto the inner surface of a drift tube which locates between the input and the middle cavity of the RKA. Cold tests show that the attenuate rate of the tube against parasitic mode TE11 is about 50%. Experiments carried out on the Torch-01 accelerator present that the tube is effective in suppressing the parasitic mode. Two typical outputs are obtained. When the diode voltage is on a moderate level, the RKA operates well and the parasitic mode is totally suppressed. The pulse length of the High Power Microwave (HPM) almost equals the electron beam pulse length and the HPM average output power is about 300 MW, with a power efficiency of 10%. When the diode voltage is on a higher level, the output power and efficiency rise but the parasitic mode oscillation occurred and the pulse length is shortened. By contrast, the parasitic mode oscillation is too strong for the RKA to operate normally with un-sintered drift tube. The experimental study implies that FeSiAl is effective in suppressing the parasitic mode oscillation in a certain extent. However, total suppression needs a deeper attenuate rate and further investigation.

  15. Experimental study on parasitic mode suppression using FeSiAl in relativistic klystron amplifier

    International Nuclear Information System (INIS)

    Zhang, Zehai

    2015-01-01

    Experimental study of parasitic mode suppression using electromagnetic attenuate material FeSiAl in an S-band Relativistic Klystron Amplifier (RKA) is presented in this paper. The FeSiAl powder is coated and sintered onto the inner surface of a drift tube which locates between the input and the middle cavity of the RKA. Cold tests show that the attenuate rate of the tube against parasitic mode TE 11 is about 50%. Experiments carried out on the Torch-01 accelerator present that the tube is effective in suppressing the parasitic mode. Two typical outputs are obtained. When the diode voltage is on a moderate level, the RKA operates well and the parasitic mode is totally suppressed. The pulse length of the High Power Microwave (HPM) almost equals the electron beam pulse length and the HPM average output power is about 300 MW, with a power efficiency of 10%. When the diode voltage is on a higher level, the output power and efficiency rise but the parasitic mode oscillation occurred and the pulse length is shortened. By contrast, the parasitic mode oscillation is too strong for the RKA to operate normally with un-sintered drift tube. The experimental study implies that FeSiAl is effective in suppressing the parasitic mode oscillation in a certain extent. However, total suppression needs a deeper attenuate rate and further investigation

  16. Cotesia vestalis parasitization suppresses expression of a Plutella xylostella thioredoxin.

    Science.gov (United States)

    Shi, M; Zhao, S; Wang, Z-H; Stanley, D; Chen, X-X

    2016-12-01

    Thioredoxins (Trxs) are a family of small, highly conserved and ubiquitous proteins involved in protecting organisms against toxic reactive oxygen species. In this study, a typical thioredoxin gene, PxTrx, was isolated from Plutella xylostella. The full-length cDNA sequence is composed of 959 bp containing a 321 bp open reading frame that encodes a predicted protein of 106 amino acids, a predicted molecular weight of 11.7 kDa and an isoelectric point of 5.03. PxTrx was mainly expressed in larval Malpighian tubules and the fat body. An enriched recombinant PxTrx had insulin disulphide reductase activity and stimulated Human Embryonic Kidney 293 (HEK293) cell proliferation. It also protected supercoiled DNA and living HEK293 cells from H 2 O 2 -induced damage. Parasitization by Cotesia vestalis and injections of 0.05 and 0.01 equivalents of C. vestalis Bracovirus (CvBv), the symbiotic virus carried by the parasitoid, led to down-regulation of PxTrx expression in host fat body. Taken together, our results indicate that PxTrx contributes to the maintenance of P. xylostella cellular haemostasis. Host fat body expression of PxTrx is strongly attenuated by parasitization and by injections of CvBv. © 2016 The Royal Entomological Society.

  17. BC047440 antisense eukaryotic expression vectors inhibited HepG2 cell proliferation and suppressed xenograft tumorigenicity

    International Nuclear Information System (INIS)

    Lu, Zheng; Ping, Liang; JianBo, Zhou; XiaoBing, Huang; Yu, Wen; Zheng, Wang; Jing, Li

    2012-01-01

    The biological functions of the BC047440 gene highly expressed by hepatocellular carcinoma (HCC) are unknown. The objective of this study was to reconstruct antisense eukaryotic expression vectors of the gene for inhibiting HepG 2 cell proliferation and suppressing their xenograft tumorigenicity. The full-length BC047440 cDNA was cloned from human primary HCC by RT-PCR. BC047440 gene fragments were ligated with pMD18-T simple vectors and subsequent pcDNA3.1(+) plasmids to construct the recombinant antisense eukaryotic vector pcDNA3.1(+)BC047440AS. The endogenous BC047440 mRNA abundance in target gene-transfected, vector-transfected and naive HepG 2 cells was semiquantitatively analyzed by RT-PCR and cell proliferation was measured by the MTT assay. Cell cycle distribution and apoptosis were profiled by flow cytometry. The in vivo xenograft experiment was performed on nude mice to examine the effects of antisense vector on tumorigenicity. BC047440 cDNA fragments were reversely inserted into pcDNA3.1(+) plasmids. The antisense vector significantly reduced the endogenous BC047440 mRNA abundance by 41% in HepG 2 cells and inhibited their proliferation in vitro (P < 0.01). More cells were arrested by the antisense vector at the G 1 phase in an apoptosis-independent manner (P = 0.014). Additionally, transfection with pcDNA3.1(+) BC047440AS significantly reduced the xenograft tumorigenicity in nude mice. As a novel cell cycle regulator associated with HCC, the BC047440 gene was involved in cell proliferation in vitro and xenograft tumorigenicity in vivo through apoptosis-independent mechanisms

  18. Suppression criteria of parasitic mode oscillations in a gyrotron beam tunnel

    Science.gov (United States)

    Kumar, Nitin; Singh, Udaybir; Singh, T. P.; Sinha, A. K.

    2011-02-01

    This paper presents the design criteria of the parasitic mode oscillations suppression for a periodic, ceramic, and copper loaded gyrotron beam tunnel. In such a type of beam tunnel, the suppression of parasitic mode oscillations is an important design problem. A method of beam-wave coupling coefficient and its mathematical formulation are presented. The developed design criteria are used in the beam tunnel design of a 42 GHz gyrotron to be developed for the Indian TOKAMAK system. The role of the thickness and the radius of the beam tunnel copper rings to obtain the developed design criteria are also discussed. The commercially available electromagnetic code CST and the electron trajectory code EGUN are used for the simulations.

  19. Suppression criteria of parasitic mode oscillations in a gyrotron beam tunnel

    International Nuclear Information System (INIS)

    Kumar, Nitin; Singh, Udaybir; Sinha, A. K.; Singh, T. P.

    2011-01-01

    This paper presents the design criteria of the parasitic mode oscillations suppression for a periodic, ceramic, and copper loaded gyrotron beam tunnel. In such a type of beam tunnel, the suppression of parasitic mode oscillations is an important design problem. A method of beam-wave coupling coefficient and its mathematical formulation are presented. The developed design criteria are used in the beam tunnel design of a 42 GHz gyrotron to be developed for the Indian TOKAMAK system. The role of the thickness and the radius of the beam tunnel copper rings to obtain the developed design criteria are also discussed. The commercially available electromagnetic code CST and the electron trajectory code EGUN are used for the simulations.

  20. Functional and phylogenetic evidence of a bacterial origin for the first enzyme in sphingolipid biosynthesis in a phylum of eukaryotic protozoan parasites.

    Science.gov (United States)

    Mina, John G; Thye, Julie K; Alqaisi, Amjed Q I; Bird, Louise E; Dods, Robert H; Grøftehauge, Morten K; Mosely, Jackie A; Pratt, Steven; Shams-Eldin, Hosam; Schwarz, Ralph T; Pohl, Ehmke; Denny, Paul W

    2017-07-21

    Toxoplasma gondii is an obligate, intracellular eukaryotic apicomplexan protozoan parasite that can cause fetal damage and abortion in both animals and humans. Sphingolipids are essential and ubiquitous components of eukaryotic membranes that are both synthesized and scavenged by the Apicomplexa. Here we report the identification, isolation, and analyses of the Toxoplasma serine palmitoyltransferase, an enzyme catalyzing the first and rate-limiting step in sphingolipid biosynthesis: the condensation of serine and palmitoyl-CoA. In all eukaryotes analyzed to date, serine palmitoyltransferase is a highly conserved heterodimeric enzyme complex. However, biochemical and structural analyses demonstrated the apicomplexan orthologue to be a functional, homodimeric serine palmitoyltransferase localized to the endoplasmic reticulum. Furthermore, phylogenetic studies indicated that it was evolutionarily related to the prokaryotic serine palmitoyltransferase, identified in the Sphingomonadaceae as a soluble homodimeric enzyme. Therefore this enzyme, conserved throughout the Apicomplexa, is likely to have been obtained via lateral gene transfer from a prokaryote. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  1. HpARI Protein Secreted by a Helminth Parasite Suppresses Interleukin-33.

    Science.gov (United States)

    Osbourn, Megan; Soares, Dinesh C; Vacca, Francesco; Cohen, E Suzanne; Scott, Ian C; Gregory, William F; Smyth, Danielle J; Toivakka, Matilda; Kemter, Andrea M; le Bihan, Thierry; Wear, Martin; Hoving, Dennis; Filbey, Kara J; Hewitson, James P; Henderson, Holly; Gonzàlez-Cìscar, Andrea; Errington, Claire; Vermeren, Sonja; Astier, Anne L; Wallace, William A; Schwarze, Jürgen; Ivens, Alasdair C; Maizels, Rick M; McSorley, Henry J

    2017-10-17

    Infection by helminth parasites is associated with amelioration of allergic reactivity, but mechanistic insights into this association are lacking. Products secreted by the mouse parasite Heligmosomoides polygyrus suppress type 2 (allergic) immune responses through interference in the interleukin-33 (IL-33) pathway. Here, we identified H. polygyrus Alarmin Release Inhibitor (HpARI), an IL-33-suppressive 26-kDa protein, containing three predicted complement control protein (CCP) modules. In vivo, recombinant HpARI abrogated IL-33, group 2 innate lymphoid cell (ILC2) and eosinophilic responses to Alternaria allergen administration, and diminished eosinophilic responses to Nippostrongylus brasiliensis, increasing parasite burden. HpARI bound directly to both mouse and human IL-33 (in the cytokine's activated state) and also to nuclear DNA via its N-terminal CCP module pair (CCP1/2), tethering active IL-33 within necrotic cells, preventing its release, and forestalling initiation of type 2 allergic responses. Thus, HpARI employs a novel molecular strategy to suppress type 2 immunity in both infection and allergy. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  2. The Romanomermis iyengari parasite for Anopheles pseudopunctipennis suppression in natural habitats in Oaxaca State, Mexico

    Directory of Open Access Journals (Sweden)

    Santamarina Mijares Alberto

    1999-01-01

    Full Text Available In September and November 1996 Romanomermis iyengari Welch, a parasite of larval mosquitoes, was released in 44 natural larval habitat sites of Anopheles pseudopunctipennis Theobald in an attempt to reduce the larval populations of this important malaria vector. The selected treatment sites ranged in size from 5 to 500 m². The study was carried out in Pochutla District of Oaxaca State, on the Pacific coast of Mexico. Chemical pesticides to reduce vector populations have been the principal tool in malaria suppression campaigns. However, the excessive use of these chemicals has created pesticide resistance and other serious collateral problems. Therefore, a biological control project using agents that are pathogens of Anopheles larvae was initiated in 1996. The principal objective was to establish mass rearing capacities for R. iyengari. Detailed methodology for rearing and introducing these nematodes into mosquito larval habitats was established at the National Polytechnic Institute of Oaxaca State. Before application of the parasites to larval habitats, site characteristics were determined, including size, depth, aquatic vegetation, salinity, pH, conductivity, temperature, and pretreatment larval density. With a compressed air sprayer, infective mermithid parasites were released at rates of either 2000 or 3000/m², and the parasites produced high levels of infection. Anopheles populations were sampled 72 h posttreatment, and the larvae obtained were taken to the laboratory and examined through microscopic dissection to determine infection levels and mean parasitism. Nematode parasitism ranged from 85 to 100% at all the treatment sites, even though no previous information concerning field parasitism of An. pseudopunctipennis by R. iyengari has been reported. In addition, a significant reduction of mosquito larval density at the treatment sites was found five days after the nematode application. Levels of parasitism were indicative of the number

  3. PfeIK1, a eukaryotic initiation factor 2α kinase of the human malaria parasite Plasmodium falciparum, regulates stress-response to amino-acid starvation

    Directory of Open Access Journals (Sweden)

    Ranford-Cartwright Lisa

    2009-05-01

    Full Text Available Abstract Background Post-transcriptional control of gene expression is suspected to play an important role in malaria parasites. In yeast and metazoans, part of the stress response is mediated through phosphorylation of eukaryotic translation initiation factor 2α (eIF2α, which results in the selective translation of mRNAs encoding stress-response proteins. Methods The impact of starvation on the phosphorylation state of PfeIF2α was examined. Bioinformatic methods were used to identify plasmodial eIF2α kinases. The activity of one of these, PfeIK1, was investigated using recombinant protein with non-physiological substrates and recombinant PfeIF2α. Reverse genetic techniques were used to disrupt the pfeik1 gene. Results The data demonstrate that the Plasmodium falciparum eIF2α orthologue is phosphorylated in response to starvation, and provide bioinformatic evidence for the presence of three eIF2α kinases in P. falciparum, only one of which (PfPK4 had been described previously. Evidence is provided that one of the novel eIF2α kinases, PfeIK1, is able to phosphorylate the P. falciparum eIF2α orthologue in vitro. PfeIK1 is not required for asexual or sexual development of the parasite, as shown by the ability of pfeik1- parasites to develop into sporozoites. However, eIF2α phosphorylation in response to starvation is abolished in pfeik1- asexual parasites Conclusion This study strongly suggests that a mechanism for versatile regulation of translation by several kinases with a similar catalytic domain but distinct regulatory domains, is conserved in P. falciparum.

  4. Suppression of parasitic oscillations in a core-doped ceramic Nd:YAG laser by Sm:YAG cladding.

    Science.gov (United States)

    Huss, Rafael; Wilhelm, Ralf; Kolleck, Christian; Neumann, Jörg; Kracht, Dietmar

    2010-06-07

    The onset of parasitic oscillations limits the extraction efficiency and therefore energy scaling of Q-switched lasers. A solid-state laser was end pumped with a fiber-coupled diode laser and operated in q-cw as well as in passively Q-switched operation. For Q-switched operation, we demonstrate the suppression of parasitic oscillations in a core-doped ceramic Nd:YAG laser by Sm:YAG cladding.

  5. Parasites

    Centers for Disease Control (CDC) Podcasts

    2010-05-06

    In this podcast, a listener wants to know what to do if he thinks he has a parasite or parasitic disease.  Created: 5/6/2010 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 5/6/2010.

  6. A Novel Meloidogyne incognita Effector Misp12 Suppresses Plant Defense Response at Latter Stages of Nematode Parasitism

    Science.gov (United States)

    Xie, Jialian; Li, Shaojun; Mo, Chenmi; Wang, Gaofeng; Xiao, Xueqiong; Xiao, Yannong

    2016-01-01

    Secreted effectors in plant root-knot nematodes (RKNs, or Meloidogyne spp.) play key roles in their parasite processes. Currently identified effectors mainly focus on the early stage of the nematode parasitism. There are only a few reports describing effectors that function in the latter stage. In this study, we identified a potential RKN effector gene, Misp12, that functioned during the latter stage of parasitism. Misp12 was unique in the Meloidogyne spp., and highly conserved in Meloidogyne incognita. It encoded a secretory protein that specifically expressed in the dorsal esophageal gland, and highly up-regulated during the female stages. Transient expression of Misp12-GUS-GFP in onion epidermal cell showed that Misp12 was localized in cytoplast. In addition, in planta RNA interference targeting Misp12 suppressed the expression of Misp12 in nematodes and attenuated parasitic ability of M. incognita. Furthermore, up-regulation of jasmonic acid (JA) and salicylic acid (SA) pathway defense-related genes in the virus-induced silencing of Misp12 plants, and down-regulation of SA pathway defense-related genes in Misp12-expressing plants indicated the gene might be associated with the suppression of the plant defense response. These results demonstrated that the novel nematode effector Misp12 played a critical role at latter parasitism of M. incognita. PMID:27446188

  7. Evidence for suppression of immunity as a driver for genomic introgressions and host range expansion in races of Albugo candida, a generalist parasite

    DEFF Research Database (Denmark)

    McMullan, Mark; Gardiner, Anastasia; Bailey, Kate

    2015-01-01

    How generalist parasites with wide host ranges can evolve is a central question in parasite evolution. Albugo candida is an obligate biotrophic parasite that consists of many physiological races that each specialize on distinct Brassicaceae host species. By analyzing genome sequence assemblies...... by normally non-infecting races. This facilitates introgression and the exchange of effector repertoires, and may enable the evolution of novel races that can undergo clonal population expansion on new hosts. We discuss recent studies on hybridization in other eukaryotes such as yeast, Heliconius butterflies...

  8. The novel GrCEP12 peptide from the plant-parasitic nematode Globodera rostochiensis suppresses flg22-mediated PTI.

    Science.gov (United States)

    Chen, Shiyan; Chronis, Demosthenis; Wang, Xiaohong

    2013-09-01

    The potato cyst nematode Globodera rostochiensis is a biotrophic pathogen that secretes effector proteins into host root cells to promote successful plant parasitism. In addition to the role in generating within root tissue the feeding cells essential for nematode development, (1) nematode secreted effectors are becoming recognized as suppressors of plant immunity. (2)(-) (4) Recently we reported that the effector ubiquitin carboxyl extension protein (GrUBCEP12) from G. rostochiensis is processed into free ubiquitin and a 12-amino acid GrCEP12 peptide in planta. Transgenic potato lines overexpressing the derived GrCEP12 peptide showed increased susceptibility to G. rostochiensis and to an unrelated bacterial pathogen Streptomyces scabies, suggesting that GrCEP12 has a role in suppressing host basal defense or possibly pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) during the parasitic interaction. (3) To determine if GrCEP12 functions as a PTI suppressor we evaluated whether GrCEP12 suppresses flg22-induced PTI responses in Nicotiana benthamiana. Interestingly, we found that transient expression of GrCEP12 in N. benthamiana leaves suppressed reactive oxygen species (ROS) production and the induction of two PTI marker genes triggered by the bacterial PAMP flg22, providing direct evidence that GrCEP12 indeed has an activity in PTI suppression.

  9. Acetate and succinate production in amoebae, helminths, diplomonads, trichomonads and trypanosomatids: common and diverse metabolic strategies used by parasitic lower eukaryotes.

    Science.gov (United States)

    Bringaud, F; Ebikeme, C; Boshart, M

    2010-08-01

    Parasites that often grow anaerobically in their hosts have adopted a fermentative strategy relying on the production of partially oxidized end products, including lactate, glycerol, ethanol, succinate and acetate. This review focuses on recent progress in understanding acetate production in protist parasites, such as amoebae, diplomonads, trichomonads, trypanosomatids and in the metazoan parasites helminths, as well as the succinate production pathway(s) present in some of them. We also describe the unconventional organisation of the tricarboxylic acid cycle associated with the fermentative strategy adopted by the procyclic trypanosomes, which may resemble the probable structure of the primordial TCA cycle in prokaryotes.

  10. Parasites and competitors suppress bacterial pathogen synergistically due to evolutionary trade-offs

    NARCIS (Netherlands)

    Wang, Xiaofang; Wei, Zhong; Li, Mei; Wang, Xueqi; Shan, Anqi; Mei, Xinlan; Jousset, Alexandre; Shen, Qirong; Xu, Yangchun; Friman, Ville Petri

    2017-01-01

    Parasites and competitors are important for regulating pathogen densities and subsequent disease dynamics. It is, however, unclear to what extent this is driven by ecological and evolutionary processes. Here, we used experimental evolution to study the eco-evolutionary feedbacks among Ralstonia

  11. Parasitic oscillation in and suppression of a gyro BW mode in a low-Q 8 GHz gyrotron

    International Nuclear Information System (INIS)

    Muggli, P.; Tran, M.Q.; Tran, T.M.

    1991-12-01

    The parasitic oscillation of the TE o 21 gyrotron Backward Wave (gyro BW) mode is observed in a low-Q, 8 GHz TE o 011 gyrotron. Although at low power (P BW o 011 mode efficiency of less than 0.25. The parasitic oscillation is suppressed by operating the gyrotron with a negative magnetic field gradient along the electron beam, which allows the maximum efficiency to reach 0.40 and the output power to be multiplied by a factor varying from 1.4 to 1.7. The optimum efficiency curve of the TE o 011 mode indicates that the low-Q cavity behaves as a much higher Q diff cavity. Too large magnetic field gradient and α values favour the TE o 012 longitudinal mode, which oscillates in place of the TE o 011 mode and limits its maximum output power. This competitive process is responsible for the high-Q like output power. (author) 14 figs., 14 refs

  12. Gammaherpesvirus Co-infection with Malaria Suppresses Anti-parasitic Humoral Immunity.

    Directory of Open Access Journals (Sweden)

    Caline G Matar

    2015-05-01

    Full Text Available Immunity to non-cerebral severe malaria is estimated to occur within 1-2 infections in areas of endemic transmission for Plasmodium falciparum. Yet, nearly 20% of infected children die annually as a result of severe malaria. Multiple risk factors are postulated to exacerbate malarial disease, one being co-infections with other pathogens. Children living in Sub-Saharan Africa are seropositive for Epstein Barr Virus (EBV by the age of 6 months. This timing overlaps with the waning of protective maternal antibodies and susceptibility to primary Plasmodium infection. However, the impact of acute EBV infection on the generation of anti-malarial immunity is unknown. Using well established mouse models of infection, we show here that acute, but not latent murine gammaherpesvirus 68 (MHV68 infection suppresses the anti-malarial humoral response to a secondary malaria infection. Importantly, this resulted in the transformation of a non-lethal P. yoelii XNL infection into a lethal one; an outcome that is correlated with a defect in the maintenance of germinal center B cells and T follicular helper (Tfh cells in the spleen. Furthermore, we have identified the MHV68 M2 protein as an important virus encoded protein that can: (i suppress anti-MHV68 humoral responses during acute MHV68 infection; and (ii plays a critical role in the observed suppression of anti-malarial humoral responses in the setting of co-infection. Notably, co-infection with an M2-null mutant MHV68 eliminates lethality of P. yoelii XNL. Collectively, our data demonstrates that an acute gammaherpesvirus infection can negatively impact the development of an anti-malarial immune response. This suggests that acute infection with EBV should be investigated as a risk factor for non-cerebral severe malaria in young children living in areas endemic for Plasmodium transmission.

  13. Comparative genome analysis of three eukaryotic parasites with differing abilities to transform leukocytes reveals key mediators of theileria-induced leukocyte transformation

    KAUST Repository

    Hayashida, Kyoko

    2012-09-04

    We sequenced the genome of Theileria orientalis, a tick-borne apicomplexan protozoan parasite of cattle. The focus of this study was a comparative genome analysis of T. orientalis relative to other highly pathogenic Theileria species, T. parva and T. annulata. T. parva and T. annulata induce transformation of infected cells of lymphocyte or macrophage/monocyte lineages; in contrast, T. orientalis does not induce uncontrolled proliferation of infected leukocytes and multiplies predominantly within infected erythrocytes. While synteny across homologous chromosomes of the three Theileria species was found to be well conserved overall, subtelomeric structures were found to differ substantially, as T. orientalis lacks the large tandemly arrayed subtelomere-encoded variable secreted protein-encoding gene family. Moreover, expansion of particular gene families by gene duplication was found in the genomes of the two transforming Theileria species, most notably, the TashAT/TpHN and Tar/Tpr gene families. Gene families that are present only in T. parva and T. annulata and not in T. orientalis, Babesia bovis, or Plasmo-dium were also identified. Identification of differences between the genome sequences of Theileria species with different abilities to transform and immortalize bovine leukocytes will provide insight into proteins and mechanisms that have evolved to induce and regulate this process. The T. orientalis genome database is available at http://totdb.czc.hokudai.ac.jp/. 2012 Hayashida et al. T.

  14. Suppression and nonlinear excitation of parasitic modes in second harmonic gyrotrons operating in a very high order mode

    International Nuclear Information System (INIS)

    Nusinovich, Gregory S.; Pu, Ruifeng; Granatstein, Victor L.

    2015-01-01

    In recent years, there was an active development of high-power, sub-terahertz (sub-THz) gyrotrons for numerous applications. For example, a 0.67 THz gyrotron delivering more than 200 kW with about 20% efficiency was developed. This record high efficiency was achieved because the gyrotron operated in a high-order TE 31,8 -mode with the power of ohmic losses less than 10% of the power of outgoing radiation. That gyrotron operated at the fundamental cyclotron resonance, and a high magnetic field of about 27 T was created by a pulse solenoid. For numerous applications, it is beneficial to use gyrotrons at cyclotron harmonics which can operate in available cryomagnets with fields not exceeding 15 T. However, typically, the gyrotron operation at harmonics faces severe competition from parasitic modes at the fundamental resonance. In the present paper, we consider a similar 0.67 THz gyrotron designed for operation in the same TE 31,8 -mode, but at the second harmonic. We focus on two nonlinear effects typical for interaction between the fundamental and second harmonic modes, viz., the mode suppression and the nonlinear excitation of the mode at the fundamental harmonic by the second harmonic oscillations. Our study includes both the analytical theory and numerical simulations performed with the self-consistent code MAGY. The simulations show that stable second harmonic operation in the TE 31,8 mode is possible with only modest sacrifice of efficiency and power

  15. Venom allergen-like proteins in secretions of plant-parasitic nematodes activate and suppress extracellular plant immune receptors

    NARCIS (Netherlands)

    Lozano Torres, J.L.

    2014-01-01

    Parasitic worms threaten human, animal and plant health by infecting people, livestock and crops worldwide. Animals and plants share an anciently evolved innate immune system. Parasites modulate this immune system by secreting proteins to maintain their parasitic lifestyle. This thesis

  16. Trans-suppression of defense DEFB1 gene in intestinal epithelial cells following Cryptosporidium parvum infection is associated with host delivery of parasite Cdg7_FLc_1000 RNA.

    Science.gov (United States)

    Ming, Zhenping; Gong, Ai-Yu; Wang, Yang; Zhang, Xin-Tian; Li, Min; Dolata, Courtney E; Chen, Xian-Ming

    2018-03-01

    To counteract host immunity, Cryptosporidium parvum has evolved multiple strategies to suppress host antimicrobial defense. One such strategy is to reduce the production of the antimicrobial peptide beta-defensin 1 (DEFB1) by host epithelial cells but the underlying mechanisms remain unclear. Recent studies demonstrate that a panel of parasite RNA transcripts of low protein-coding potential are delivered into infected host cells and may modulate host gene transcription. Using in vitro models of intestinal cryptosporidiosis, in this study, we analyzed the expression profile of host beta-defensin genes in host cells following infection. We found that C. parvum infection caused a significant downregulation of the DEFB1 gene. Interestingly, downregulation of DEFB1 gene was associated with host delivery of Cdg7_FLc_1000 RNA transcript, a C. parvum RNA that has previously demonstrated to be delivered into the nuclei of infected host cells. Knockdown of Cdg7_FLc_1000 in host cells could attenuate the trans-suppression of host DEFB1 gene and decreased the parasite burden. Therefore, our data suggest that trans-suppression of DEFB1 gene in intestinal epithelial cells following C. parvum infection involves host delivery of parasite Cdg7_FLc_1000 RNA, a process that may be relevant to the epithelial defense evasion by C. parvum at the early stage of infection.

  17. A novel Meloidogyne graminicola effector, MgGPP, is secreted into host cells and undergoes glycosylation in concert with proteolysis to suppress plant defenses and promote parasitism.

    Directory of Open Access Journals (Sweden)

    Jiansong Chen

    2017-04-01

    Full Text Available Plant pathogen effectors can recruit the host post-translational machinery to mediate their post-translational modification (PTM and regulate their activity to facilitate parasitism, but few studies have focused on this phenomenon in the field of plant-parasitic nematodes. In this study, we show that the plant-parasitic nematode Meloidogyne graminicola has evolved a novel effector, MgGPP, that is exclusively expressed within the nematode subventral esophageal gland cells and up-regulated in the early parasitic stage of M. graminicola. The effector MgGPP plays a role in nematode parasitism. Transgenic rice lines expressing MgGPP become significantly more susceptible to M. graminicola infection than wild-type control plants, and conversely, in planta, the silencing of MgGPP through RNAi technology substantially increases the resistance of rice to M. graminicola. Significantly, we show that MgGPP is secreted into host plants and targeted to the ER, where the N-glycosylation and C-terminal proteolysis of MgGPP occur. C-terminal proteolysis promotes MgGPP to leave the ER, after which it is transported to the nucleus. In addition, N-glycosylation of MgGPP is required for suppressing the host response. The research data provide an intriguing example of in planta glycosylation in concert with proteolysis of a pathogen effector, which depict a novel mechanism by which parasitic nematodes could subjugate plant immunity and promote parasitism and may present a promising target for developing new strategies against nematode infections.

  18. Trans-suppression of host CDH3 and LOXL4 genes during Cryptosporidium parvum infection involves nuclear delivery of parasite Cdg7_FLc_1000 RNA.

    Science.gov (United States)

    Ming, Zhenping; Gong, Ai-Yu; Wang, Yang; Zhang, Xin-Tian; Li, Min; Li, Yao; Pang, Jing; Dong, Stephanie; Strauss-Soukup, Juliane K; Chen, Xian-Ming

    2018-05-01

    Intestinal infection by Cryptosporidium parvum causes significant alterations in the gene expression profile in host epithelial cells. Previous studies demonstrate that a panel of parasite RNA transcripts of low protein-coding potential are delivered into infected host cells and may modulate host gene transcription. Using in vitro models of human intestinal cryptosporidiosis, we report here that trans-suppression of the cadherin 3 (CDH3) and lysyl oxidase like 4 (LOXL4) genes in human intestinal epithelial cells following C. parvum infection involves host delivery of the Cdg7_FLc_1000 RNA, a C. parvum RNA that has been previously demonstrated to be delivered into the nuclei of infected host cells. Downregulation of CDH3 and LOXL4 genes was detected in host epithelial cells following C. parvum infection or in cells expressing the parasite Cdg7_FLc_1000 RNA. Knockdown of Cdg7_FLc_1000 attenuated the trans-suppression of CDH3 and LOXL4 genes in host cells induced by infection. Interestingly, Cdg7_FLc_1000 was detected to be recruited to the promoter regions of both CDH3 and LOXL4 gene loci in host cells following C. parvum infection. Host delivery of Cdg7_FLc_1000 promoted the PH domain zinc finger protein 1 (PRDM1)-mediated H3K9 methylation associated with trans-suppression in the CDH3 gene locus, but not the LOXL4 gene. Therefore, our data suggest that host delivery of Cdg7_FLc_1000 causes CDH3 trans-suppression in human intestinal epithelial cells following C. parvum infection through PRDM1-mediated H3K9 methylation in the CDH3 gene locus, whereas Cdg7_FLc_1000 induces trans-suppression of the host LOXL4 gene through H3K9/H3K27 methylation-independent mechanisms. Copyright © 2018 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.

  19. Schistosoma mansoni infection suppresses the growth of Plasmodium yoelii parasites in the liver and reduces gametocyte infectivity to mosquitoes.

    Directory of Open Access Journals (Sweden)

    Taeko Moriyasu

    2018-01-01

    Full Text Available Malaria and schistosomiasis are major parasitic diseases causing morbidity and mortality in the tropics. Epidemiological surveys have revealed coinfection rates of up to 30% among children in Sub-Saharan Africa. To investigate the impact of coinfection of these two parasites on disease epidemiology and pathology, we carried out coinfection studies using Plasmodium yoelii and Schistosoma mansoni in mice. Malaria parasite growth in the liver following sporozoite inoculation is significantly inhibited in mice infected with S. mansoni, so that when low numbers of sporozoites are inoculated, there is a large reduction in the percentage of mice that go on to develop blood stage malaria. Furthermore, gametocyte infectivity is much reduced in mice with S. mansoni infections. These results have profound implications for understanding the interactions between Plasmodium and Schistosoma species, and have implications for the control of malaria in schistosome endemic areas.

  20. Single Cell Genomics and Transcriptomics for Unicellular Eukaryotes

    Energy Technology Data Exchange (ETDEWEB)

    Ciobanu, Doina; Clum, Alicia; Singh, Vasanth; Salamov, Asaf; Han, James; Copeland, Alex; Grigoriev, Igor; James, Timothy; Singer, Steven; Woyke, Tanja; Malmstrom, Rex; Cheng, Jan-Fang

    2014-03-14

    Despite their small size, unicellular eukaryotes have complex genomes with a high degree of plasticity that allow them to adapt quickly to environmental changes. Unicellular eukaryotes live with prokaryotes and higher eukaryotes, frequently in symbiotic or parasitic niches. To this day their contribution to the dynamics of the environmental communities remains to be understood. Unfortunately, the vast majority of eukaryotic microorganisms are either uncultured or unculturable, making genome sequencing impossible using traditional approaches. We have developed an approach to isolate unicellular eukaryotes of interest from environmental samples, and to sequence and analyze their genomes and transcriptomes. We have tested our methods with six species: an uncharacterized protist from cellulose-enriched compost identified as Platyophrya, a close relative of P. vorax; the fungus Metschnikowia bicuspidate, a parasite of water flea Daphnia; the mycoparasitic fungi Piptocephalis cylindrospora, a parasite of Cokeromyces and Mucor; Caulochytrium protosteloides, a parasite of Sordaria; Rozella allomycis, a parasite of the water mold Allomyces; and the microalgae Chlamydomonas reinhardtii. Here, we present the four components of our approach: pre-sequencing methods, sequence analysis for single cell genome assembly, sequence analysis of single cell transcriptomes, and genome annotation. This technology has the potential to uncover the complexity of single cell eukaryotes and their role in the environmental samples.

  1. Protein moonlighting in parasitic protists.

    Science.gov (United States)

    Ginger, Michael L

    2014-12-01

    Reductive evolution during the adaptation to obligate parasitism and expansions of gene families encoding virulence factors are characteristics evident to greater or lesser degrees in all parasitic protists studied to date. Large evolutionary distances separate many parasitic protists from the yeast and animal models upon which classic views of eukaryotic biochemistry are often based. Thus a combination of evolutionary divergence, niche adaptation and reductive evolution means the biochemistry of parasitic protists is often very different from their hosts and to other eukaryotes generally, making parasites intriguing subjects for those interested in the phenomenon of moonlighting proteins. In common with other organisms, the contribution of protein moonlighting to parasite biology is only just emerging, and it is not without controversy. Here, an overview of recently identified moonlighting proteins in parasitic protists is provided, together with discussion of some of the controversies.

  2. Communities of microbial eukaryotes in the mammalian gut within the context of environmental eukaryotic diversity

    Energy Technology Data Exchange (ETDEWEB)

    Parfrey, Laura Wegener; Walters, William A.; Lauber, Christian L.; Clemente, Jose C.; Berg-Lyons, Donna; Teiling, Clotilde; Kodira, Chinnappa; Mohiuddin, Mohammed; Brunelle, Julie; Driscoll, Mark; Fierer, Noah; Gilbert, Jack A.; Knight, Rob

    2014-06-19

    Eukaryotic microbes (protists) residing in the vertebrate gut influence host health and disease, but their diversity and distribution in healthy hosts is poorly understood. Protists found in the gut are typically considered parasites, but many are commensal and some are beneficial. Further, the hygiene hypothesis predicts that association with our co-evolved microbial symbionts may be important to overall health. It is therefore imperative that we understand the normal diversity of our eukaryotic gut microbiota to test for such effects and avoid eliminating commensal organisms. We assembled a dataset of healthy individuals from two populations, one with traditional, agrarian lifestyles and a second with modern, westernized lifestyles, and characterized the human eukaryotic microbiota via high-throughput sequencing. To place the human gut microbiota within a broader context our dataset also includes gut samples from diverse mammals and samples from other aquatic and terrestrial environments. We curated the SILVA ribosomal database to reflect current knowledge of eukaryotic taxonomy and employ it as a phylogenetic framework to compare eukaryotic diversity across environment. We show that adults from the non-western population harbor a diverse community of protists, and diversity in the human gut is comparable to that in other mammals. However, the eukaryotic microbiota of the western population appears depauperate. The distribution of symbionts found in mammals reflects both host phylogeny and diet. Eukaryotic microbiota in the gut are less diverse and more patchily distributed than bacteria. More broadly, we show that eukaryotic communities in the gut are less diverse than in aquatic and terrestrial habitats, and few taxa are shared across habitat types, and diversity patterns of eukaryotes are correlated with those observed for bacteria. These results outline the distribution and diversity of microbial eukaryotic communities in the mammalian gut and across

  3. Parasitic lasing suppression in large-aperture Ti:sapphire amplifiers by optimizing the seed–pump time delay

    International Nuclear Information System (INIS)

    Chu, Y X; Liang, X Y; Yu, L H; Xu, L; Lu, X M; Liu, Y Q; Leng, Y X; Li, R X; Xu, Z Z

    2013-01-01

    Theoretical and experimental investigations are carried out to determine the influence of the time delay between the input seed pulse and pump pulses on transverse parasitic lasing in a Ti:sapphire amplifier with a diameter of 80 mm, which is clad by a refractive index-matched liquid doped with an absorber. When the time delay is optimized, a maximum output energy of 50.8 J is achieved at a pump energy of 105 J, which corresponds to a conversion efficiency of 47.5%. Based on the existing compressor, the laser system achieves a peak power of 1.26 PW with a 29.0 fs pulse duration. (letter)

  4. The parasitic plant Cuscuta australis is highly insensitive to abscisic acid-induced suppression of hypocotyl elongation and seed germination.

    Science.gov (United States)

    Li, Juan; Hettenhausen, Christian; Sun, Guiling; Zhuang, Huifu; Li, Jian-Hong; Wu, Jianqiang

    2015-01-01

    Around 1% of angiosperms are parasitic plants. Their growth and development solely or partly depend on host plants from which they extract water, nutrients, and other molecules using a parasitic plant-specific organ, the haustorium. Strong depletion of nutrients can result in serious growth retardation and in some cases, death of the hosts. The genus Cuscuta (dodder) comprises about 200 holoparasitic species occurring on all continents. Their seedlings have no roots and cotyledons but are only string-like hypocotyls. When they contact suitable host plants, haustoria are formed and thereafter seedlings rapidly develop into vigorously growing branches without roots and leaves. This highly specialized lifestyle suggests that Cuscuta plants likely have unique physiology in development and stress responses. Using germination and seedling growth assays, we show that C. australis seeds and seedlings are highly insensitive to abscisic acid (ABA). Transcriptome analysis and protein sequence alignment with Arabidopsis, tomato, and rice homologs revealed that C. australis most likely consists of only four functional ABA receptors. Given that Cuscuta plants are no longer severely challenged by drought stress, we hypothesize that the ABA-mediated drought resistance pathway in Cuscuta spp. might have had degenerated over time during evolution.

  5. The parasitic plant Cuscuta australis is highly insensitive to abscisic acid-induced suppression of hypocotyl elongation and seed germination.

    Directory of Open Access Journals (Sweden)

    Juan Li

    Full Text Available Around 1% of angiosperms are parasitic plants. Their growth and development solely or partly depend on host plants from which they extract water, nutrients, and other molecules using a parasitic plant-specific organ, the haustorium. Strong depletion of nutrients can result in serious growth retardation and in some cases, death of the hosts. The genus Cuscuta (dodder comprises about 200 holoparasitic species occurring on all continents. Their seedlings have no roots and cotyledons but are only string-like hypocotyls. When they contact suitable host plants, haustoria are formed and thereafter seedlings rapidly develop into vigorously growing branches without roots and leaves. This highly specialized lifestyle suggests that Cuscuta plants likely have unique physiology in development and stress responses. Using germination and seedling growth assays, we show that C. australis seeds and seedlings are highly insensitive to abscisic acid (ABA. Transcriptome analysis and protein sequence alignment with Arabidopsis, tomato, and rice homologs revealed that C. australis most likely consists of only four functional ABA receptors. Given that Cuscuta plants are no longer severely challenged by drought stress, we hypothesize that the ABA-mediated drought resistance pathway in Cuscuta spp. might have had degenerated over time during evolution.

  6. How does the suppression of energy supplementation affect herbage intake, performance and parasitism in lactating saddle mares?

    Science.gov (United States)

    Collas, C; Fleurance, G; Cabaret, J; Martin-Rosset, W; Wimel, L; Cortet, J; Dumont, B

    2014-08-01

    Agroecology opens up new perspectives for the design of sustainable farming systems by using the stimulation of natural processes to reduce the inputs needed for production. In horse farming systems, the challenge is to maximize the proportion of forages in the diet, and to develop alternatives to synthetic chemical drugs for controlling gastrointestinal nematodes. Lactating saddle mares, with high nutritional requirements, are commonly supplemented with concentrates at pasture, although the influence of energy supplementation on voluntary intake, performance and immune response against parasites has not yet been quantified. In a 4-month study, 16 lactating mares experimentally infected with cyathostome larvae either received a daily supplement of barley (60% of energy requirements for lactation) or were non-supplemented. The mares were rotationally grazed on permanent pastures over three vegetation cycles. All the mares met their energy requirements and maintained their body condition score higher than 3. In both treatments, they produced foals with a satisfying growth rate (cycle 1: 1293 g/day; cycle 2: 1029 g/day; cycle 3: 559 g/day) and conformation (according to measurements of height at withers and cannon bone width at 11 months). Parasite egg excretion by mares increased in both groups during the grazing season (from 150 to 2011 epg), independently of whether they were supplemented or not. This suggests that energy supplementation did not improve mare ability to regulate parasite burden. Under unlimited herbage conditions, grass dry matter intake by supplemented mares remained stable around 22.6 g DM/kg LW per day (i.e. 13.5 kg DM/al per day), whereas non-supplemented mares increased voluntary intake from 22.6 to 28.0 g DM/kg LW per day (13.5 to 17.2 kg DM/al per day) between mid-June and the end of August. Hence total digestible dry matter intake and net energy intake did not significantly differ between supplemented and non-supplemented mares during the

  7. One Health: parasites and beyond…

    OpenAIRE

    Blake, DP; Betson, ME

    2016-01-01

    The field of parasitism is broad, encompassing relationships between organisms where one benefits at the expense of another. Traditionally the discipline focuses on eukaryotes, with the study of bacteria and viruses complementary but distinct. Nonetheless, parasites vary in size and complexity from single celled protozoa, to enormous plants like those in the genus Rafflesia. Lifecycles range from obligate intracellular to extensive exoparasitism. Examples of parasites include high profile med...

  8. Autophagy in unicellular eukaryotes

    NARCIS (Netherlands)

    Kiel, J.A.K.W.

    2010-01-01

    Cells need a constant supply of precursors to enable the production of macromolecules to sustain growth and survival. Unlike metazoans, unicellular eukaryotes depend exclusively on the extracellular medium for this supply. When environmental nutrients become depleted, existing cytoplasmic components

  9. Dynamic protein S-palmitoylation mediates parasite life cycle progression and diverse mechanisms of virulence.

    Science.gov (United States)

    Brown, Robert W B; Sharma, Aabha I; Engman, David M

    2017-04-01

    Eukaryotic parasites possess complex life cycles and utilize an assortment of molecular mechanisms to overcome physical barriers, suppress and/or bypass the host immune response, including invading host cells where they can replicate in a protected intracellular niche. Protein S-palmitoylation is a dynamic post-translational modification in which the fatty acid palmitate is covalently linked to cysteine residues on proteins by the enzyme palmitoyl acyltransferase (PAT) and can be removed by lysosomal palmitoyl-protein thioesterase (PPT) or cytosolic acyl-protein thioesterase (APT). In addition to anchoring proteins to intracellular membranes, functions of dynamic palmitoylation include - targeting proteins to specific intracellular compartments via trafficking pathways, regulating the cycling of proteins between membranes, modulating protein function and regulating protein stability. Recent studies in the eukaryotic parasites - Plasmodium falciparum, Toxoplasma gondii, Trypanosoma brucei, Cryptococcus neoformans and Giardia lamblia - have identified large families of PATs and palmitoylated proteins. Many palmitoylated proteins are important for diverse aspects of pathogenesis, including differentiation into infective life cycle stages, biogenesis and tethering of secretory organelles, assembling the machinery powering motility and targeting virulence factors to the plasma membrane. This review aims to summarize our current knowledge of palmitoylation in eukaryotic parasites, highlighting five exemplary mechanisms of parasite virulence dependent on palmitoylation.

  10. Multilevel Empirical Bayes Modeling for Improved Estimation of Toxicant Formulations to Suppress Parasitic Sea Lamprey in the Upper Great Lakes

    Science.gov (United States)

    Hatfield, L.A.; Gutreuter, S.; Boogaard, M.A.; Carlin, B.P.

    2011-01-01

    Estimation of extreme quantal-response statistics, such as the concentration required to kill 99.9% of test subjects (LC99.9), remains a challenge in the presence of multiple covariates and complex study designs. Accurate and precise estimates of the LC99.9 for mixtures of toxicants are critical to ongoing control of a parasitic invasive species, the sea lamprey, in the Laurentian Great Lakes of North America. The toxicity of those chemicals is affected by local and temporal variations in water chemistry, which must be incorporated into the modeling. We develop multilevel empirical Bayes models for data from multiple laboratory studies. Our approach yields more accurate and precise estimation of the LC99.9 compared to alternative models considered. This study demonstrates that properly incorporating hierarchical structure in laboratory data yields better estimates of LC99.9 stream treatment values that are critical to larvae control in the field. In addition, out-of-sample prediction of the results of in situ tests reveals the presence of a latent seasonal effect not manifest in the laboratory studies, suggesting avenues for future study and illustrating the importance of dual consideration of both experimental and observational data. ?? 2011, The International Biometric Society.

  11. Eukaryotic systematics: a user's guide for cell biologists and parasitologists.

    Science.gov (United States)

    Walker, Giselle; Dorrell, Richard G; Schlacht, Alexander; Dacks, Joel B

    2011-11-01

    Single-celled parasites like Entamoeba, Trypanosoma, Phytophthora and Plasmodium wreak untold havoc on human habitat and health. Understanding the position of the various protistan pathogens in the larger context of eukaryotic diversity informs our study of how these parasites operate on a cellular level, as well as how they have evolved. Here, we review the literature that has brought our understanding of eukaryotic relationships from an idea of parasites as primitive cells to a crystallized view of diversity that encompasses 6 major divisions, or supergroups, of eukaryotes. We provide an updated taxonomic scheme (for 2011), based on extensive genomic, ultrastructural and phylogenetic evidence, with three differing levels of taxonomic detail for ease of referencing and accessibility (see supplementary material at Cambridge Journals On-line). Two of the most pressing issues in cellular evolution, the root of the eukaryotic tree and the evolution of photosynthesis in complex algae, are also discussed along with ideas about what the new generation of genome sequencing technologies may contribute to the field of eukaryotic systematics. We hope that, armed with this user's guide, cell biologists and parasitologists will be encouraged about taking an increasingly evolutionary point of view in the battle against parasites representing real dangers to our livelihoods and lives.

  12. Biochar-enhanced composts reduce the potential leaching of nutrients and heavy metals and suppress plant-parasitic nematodes in excessively fertilized cucumber soils.

    Science.gov (United States)

    Cao, Yune; Gao, Yanming; Qi, Yanbin; Li, Jianshe

    2018-03-01

    Excessive fertilization is a common agricultural practice that has largely reduced soil nutrient retention capacity and led to nutrient leaching in China. To reduce nutrient leaching, in this study, we evaluated the application of biochar, compost, and biochar-compost on soil properties, leaching water quality, and cucumber plant growth in soils with different nutrient levels. In general, the concentrations of nutrients and heavy metals in leaching water were higher under high-nutrient conditions than under low-nutrient conditions. Both biochar and compost efficiently enhanced soil cation exchange capacity (CEC), water holding capacity (WHC), and microbial biomass carbon (MBC), nitrogen (MBN), and phosphorus (MBP), reduced the potential leaching of nutrients and heavy metals, and improved plant growth. The efficiency of biochar and compost in soil CEC, WHC, MBC, MBN, and MBP and plant growth was enhanced when applied jointly. In addition, biochar and biochar-enhanced compost efficiently suppressed plant-parasitic nematode infestation in a soil with high levels of both N and P. Our results suggest that biochar-enhanced compost can reduce the potential environmental risks in excessively fertilized vegetable soils.

  13. Towards New Antifolates Targeting Eukaryotic Opportunistic Infections

    Energy Technology Data Exchange (ETDEWEB)

    Liu, J.; Bolstad, D; Bolstad, E; Wright, D; Anderson, A

    2009-01-01

    Trimethoprim, an antifolate commonly prescribed in combination with sulfamethoxazole, potently inhibits several prokaryotic species of dihydrofolate reductase (DHFR). However, several eukaryotic pathogenic organisms are resistant to trimethoprim, preventing its effective use as a therapeutic for those infections. We have been building a program to reengineer trimethoprim to more potently and selectively inhibit eukaryotic species of DHFR as a viable strategy for new drug discovery targeting several opportunistic pathogens. We have developed a series of compounds that exhibit potent and selective inhibition of DHFR from the parasitic protozoa Cryptosporidium and Toxoplasma as well as the fungus Candida glabrata. A comparison of the structures of DHFR from the fungal species Candida glabrata and Pneumocystis suggests that the compounds may also potently inhibit Pneumocystis DHFR.

  14. Inorganic phosphate uptake in unicellular eukaryotes.

    Science.gov (United States)

    Dick, Claudia F; Dos-Santos, André L A; Meyer-Fernandes, José R

    2014-07-01

    Inorganic phosphate (Pi) is an essential nutrient for all organisms. The route of Pi utilization begins with Pi transport across the plasma membrane. Here, we analyzed the gene sequences and compared the biochemical profiles, including kinetic and modulator parameters, of Pi transporters in unicellular eukaryotes. The objective of this review is to evaluate the recent findings regarding Pi uptake mechanisms in microorganisms, such as the fungi Neurospora crassa and Saccharomyces cerevisiae and the parasite protozoans Trypanosoma cruzi, Trypanosoma rangeli, Leishmania infantum and Plasmodium falciparum. Pi uptake is the key step of Pi homeostasis and in the subsequent signaling event in eukaryotic microorganisms. Biochemical and structural studies are important for clarifying mechanisms of Pi homeostasis, as well as Pi sensor and downstream pathways, and raise possibilities for future studies in this field. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Eukaryotic Cell Panorama

    Science.gov (United States)

    Goodsell, David S.

    2011-01-01

    Diverse biological data may be used to create illustrations of molecules in their cellular context. This report describes the scientific results that support an illustration of a eukaryotic cell, enlarged by one million times to show the distribution and arrangement of macromolecules. The panoramic cross section includes eight panels that extend…

  16. Eukaryotic cell flattening

    Science.gov (United States)

    Bae, Albert; Westendorf, Christian; Erlenkamper, Christoph; Galland, Edouard; Franck, Carl; Bodenschatz, Eberhard; Beta, Carsten

    2010-03-01

    Eukaryotic cell flattening is valuable for improving microscopic observations, ranging from bright field to total internal reflection fluorescence microscopy. In this talk, we will discuss traditional overlay techniques, and more modern, microfluidic based flattening, which provides a greater level of control. We demonstrate these techniques on the social amoebae Dictyostelium discoideum, comparing the advantages and disadvantages of each method.

  17. Comparative Genomics of Eukaryotes.

    NARCIS (Netherlands)

    Noort, V. van

    2007-01-01

    This thesis focuses on developing comparative genomics methods in eukaryotes, with an emphasis on applications for gene function prediction and regulatory element detection. In the past, methods have been developed to predict functional associations between gene pairs in prokaryotes. The challenge

  18. The COG database: an updated version includes eukaryotes

    Directory of Open Access Journals (Sweden)

    Sverdlov Alexander V

    2003-09-01

    Full Text Available Abstract Background The availability of multiple, essentially complete genome sequences of prokaryotes and eukaryotes spurred both the demand and the opportunity for the construction of an evolutionary classification of genes from these genomes. Such a classification system based on orthologous relationships between genes appears to be a natural framework for comparative genomics and should facilitate both functional annotation of genomes and large-scale evolutionary studies. Results We describe here a major update of the previously developed system for delineation of Clusters of Orthologous Groups of proteins (COGs from the sequenced genomes of prokaryotes and unicellular eukaryotes and the construction of clusters of predicted orthologs for 7 eukaryotic genomes, which we named KOGs after eukaryotic orthologous groups. The COG collection currently consists of 138,458 proteins, which form 4873 COGs and comprise 75% of the 185,505 (predicted proteins encoded in 66 genomes of unicellular organisms. The eukaryotic orthologous groups (KOGs include proteins from 7 eukaryotic genomes: three animals (the nematode Caenorhabditis elegans, the fruit fly Drosophila melanogaster and Homo sapiens, one plant, Arabidopsis thaliana, two fungi (Saccharomyces cerevisiae and Schizosaccharomyces pombe, and the intracellular microsporidian parasite Encephalitozoon cuniculi. The current KOG set consists of 4852 clusters of orthologs, which include 59,838 proteins, or ~54% of the analyzed eukaryotic 110,655 gene products. Compared to the coverage of the prokaryotic genomes with COGs, a considerably smaller fraction of eukaryotic genes could be included into the KOGs; addition of new eukaryotic genomes is expected to result in substantial increase in the coverage of eukaryotic genomes with KOGs. Examination of the phyletic patterns of KOGs reveals a conserved core represented in all analyzed species and consisting of ~20% of the KOG set. This conserved portion of the

  19. Arsenic and Antimony Transporters in Eukaryotes

    Directory of Open Access Journals (Sweden)

    Ewa Maciaszczyk-Dziubinska

    2012-03-01

    Full Text Available Arsenic and antimony are toxic metalloids, naturally present in the environment and all organisms have developed pathways for their detoxification. The most effective metalloid tolerance systems in eukaryotes include downregulation of metalloid uptake, efflux out of the cell, and complexation with phytochelatin or glutathione followed by sequestration into the vacuole. Understanding of arsenic and antimony transport system is of high importance due to the increasing usage of arsenic-based drugs in the treatment of certain types of cancer and diseases caused by protozoan parasites as well as for the development of bio- and phytoremediation strategies for metalloid polluted areas. However, in contrast to prokaryotes, the knowledge about specific transporters of arsenic and antimony and the mechanisms of metalloid transport in eukaryotes has been very limited for a long time. Here, we review the recent advances in understanding of arsenic and antimony transport pathways in eukaryotes, including a dual role of aquaglyceroporins in uptake and efflux of metalloids, elucidation of arsenic transport mechanism by the yeast Acr3 transporter and its role in arsenic hyperaccumulation in ferns, identification of vacuolar transporters of arsenic-phytochelatin complexes in plants and forms of arsenic substrates recognized by mammalian ABC transporters.

  20. Arsenic and Antimony Transporters in Eukaryotes

    Science.gov (United States)

    Maciaszczyk-Dziubinska, Ewa; Wawrzycka, Donata; Wysocki, Robert

    2012-01-01

    Arsenic and antimony are toxic metalloids, naturally present in the environment and all organisms have developed pathways for their detoxification. The most effective metalloid tolerance systems in eukaryotes include downregulation of metalloid uptake, efflux out of the cell, and complexation with phytochelatin or glutathione followed by sequestration into the vacuole. Understanding of arsenic and antimony transport system is of high importance due to the increasing usage of arsenic-based drugs in the treatment of certain types of cancer and diseases caused by protozoan parasites as well as for the development of bio- and phytoremediation strategies for metalloid polluted areas. However, in contrast to prokaryotes, the knowledge about specific transporters of arsenic and antimony and the mechanisms of metalloid transport in eukaryotes has been very limited for a long time. Here, we review the recent advances in understanding of arsenic and antimony transport pathways in eukaryotes, including a dual role of aquaglyceroporins in uptake and efflux of metalloids, elucidation of arsenic transport mechanism by the yeast Acr3 transporter and its role in arsenic hyperaccumulation in ferns, identification of vacuolar transporters of arsenic-phytochelatin complexes in plants and forms of arsenic substrates recognized by mammalian ABC transporters. PMID:22489166

  1. Origins and evolution of viruses of eukaryotes: The ultimate modularity

    International Nuclear Information System (INIS)

    Koonin, Eugene V.; Dolja, Valerian V.; Krupovic, Mart

    2015-01-01

    Viruses and other selfish genetic elements are dominant entities in the biosphere, with respect to both physical abundance and genetic diversity. Various selfish elements parasitize on all cellular life forms. The relative abundances of different classes of viruses are dramatically different between prokaryotes and eukaryotes. In prokaryotes, the great majority of viruses possess double-stranded (ds) DNA genomes, with a substantial minority of single-stranded (ss) DNA viruses and only limited presence of RNA viruses. In contrast, in eukaryotes, RNA viruses account for the majority of the virome diversity although ssDNA and dsDNA viruses are common as well. Phylogenomic analysis yields tangible clues for the origins of major classes of eukaryotic viruses and in particular their likely roots in prokaryotes. Specifically, the ancestral genome of positive-strand RNA viruses of eukaryotes might have been assembled de novo from genes derived from prokaryotic retroelements and bacteria although a primordial origin of this class of viruses cannot be ruled out. Different groups of double-stranded RNA viruses derive either from dsRNA bacteriophages or from positive-strand RNA viruses. The eukaryotic ssDNA viruses apparently evolved via a fusion of genes from prokaryotic rolling circle-replicating plasmids and positive-strand RNA viruses. Different families of eukaryotic dsDNA viruses appear to have originated from specific groups of bacteriophages on at least two independent occasions. Polintons, the largest known eukaryotic transposons, predicted to also form virus particles, most likely, were the evolutionary intermediates between bacterial tectiviruses and several groups of eukaryotic dsDNA viruses including the proposed order “Megavirales” that unites diverse families of large and giant viruses. Strikingly, evolution of all classes of eukaryotic viruses appears to have involved fusion between structural and replicative gene modules derived from different sources

  2. Origins and evolution of viruses of eukaryotes: The ultimate modularity

    Energy Technology Data Exchange (ETDEWEB)

    Koonin, Eugene V., E-mail: koonin@ncbi.nlm.nih.gov [National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894 (United States); Dolja, Valerian V., E-mail: doljav@science.oregonstate.edu [Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331 (United States); Krupovic, Mart, E-mail: krupovic@pasteur.fr [Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Department of Microbiology, Paris 75015 (France)

    2015-05-15

    Viruses and other selfish genetic elements are dominant entities in the biosphere, with respect to both physical abundance and genetic diversity. Various selfish elements parasitize on all cellular life forms. The relative abundances of different classes of viruses are dramatically different between prokaryotes and eukaryotes. In prokaryotes, the great majority of viruses possess double-stranded (ds) DNA genomes, with a substantial minority of single-stranded (ss) DNA viruses and only limited presence of RNA viruses. In contrast, in eukaryotes, RNA viruses account for the majority of the virome diversity although ssDNA and dsDNA viruses are common as well. Phylogenomic analysis yields tangible clues for the origins of major classes of eukaryotic viruses and in particular their likely roots in prokaryotes. Specifically, the ancestral genome of positive-strand RNA viruses of eukaryotes might have been assembled de novo from genes derived from prokaryotic retroelements and bacteria although a primordial origin of this class of viruses cannot be ruled out. Different groups of double-stranded RNA viruses derive either from dsRNA bacteriophages or from positive-strand RNA viruses. The eukaryotic ssDNA viruses apparently evolved via a fusion of genes from prokaryotic rolling circle-replicating plasmids and positive-strand RNA viruses. Different families of eukaryotic dsDNA viruses appear to have originated from specific groups of bacteriophages on at least two independent occasions. Polintons, the largest known eukaryotic transposons, predicted to also form virus particles, most likely, were the evolutionary intermediates between bacterial tectiviruses and several groups of eukaryotic dsDNA viruses including the proposed order “Megavirales” that unites diverse families of large and giant viruses. Strikingly, evolution of all classes of eukaryotic viruses appears to have involved fusion between structural and replicative gene modules derived from different sources

  3. Eukaryotic DNA Replication Fork.

    Science.gov (United States)

    Burgers, Peter M J; Kunkel, Thomas A

    2017-06-20

    This review focuses on the biogenesis and composition of the eukaryotic DNA replication fork, with an emphasis on the enzymes that synthesize DNA and repair discontinuities on the lagging strand of the replication fork. Physical and genetic methodologies aimed at understanding these processes are discussed. The preponderance of evidence supports a model in which DNA polymerase ε (Pol ε) carries out the bulk of leading strand DNA synthesis at an undisturbed replication fork. DNA polymerases α and δ carry out the initiation of Okazaki fragment synthesis and its elongation and maturation, respectively. This review also discusses alternative proposals, including cellular processes during which alternative forks may be utilized, and new biochemical studies with purified proteins that are aimed at reconstituting leading and lagging strand DNA synthesis separately and as an integrated replication fork.

  4. [What makes a parasite "transforming"? Insights into cancer from the agents of an exotic pathology, Theileria spp].

    Science.gov (United States)

    Cheeseman, K M; Weitzman, J B

    2017-02-01

    Theileria are obligate eukaryotic intracellular parasites of cattle. The diseases they cause, Tropical theileriosis and East Coast Fever, cause huge economic loss in East African, Mediterranean and central and South-East Asian countries. These apicomplexan parasites are the only intracellular eukaryotic parasites known to transform their host cell and represent a unique model to study host-parasite interactions and mechanisms of cancer onset.Here, we review how Theileria parasites induce transformation of their leukocyte host cell and discuss similarities with tumorigenesis. We describe how genomic innovation, epigenetic changes and hijacking of signal transductions enable a eukaryotic parasite to transform its host cell.

  5. Eukaryotic DNA Replicases

    KAUST Repository

    Zaher, Manal S.; Oke, Muse; Hamdan, Samir

    2014-01-01

    The current model of the eukaryotic DNA replication fork includes three replicative DNA polymerases, polymerase α/primase complex (Pol α), polymerase δ (Pol δ), and polymerase ε (Pol ε). The primase synthesizes 8–12 nucleotide RNA primers that are extended by the DNA polymerization activity of Pol α into 30–35 nucleotide RNA-DNA primers. Replication factor C (RFC) opens the polymerase clamp-like processivity factor, proliferating cell nuclear antigen (PCNA), and loads it onto the primer-template. Pol δ utilizes PCNA to mediate highly processive DNA synthesis, while Pol ε has intrinsic high processivity that is modestly stimulated by PCNA. Pol ε replicates the leading strand and Pol δ replicates the lagging strand in a division of labor that is not strict. The three polymerases are comprised of multiple subunits and share unifying features in their large catalytic and B subunits. The remaining subunits are evolutionarily not related and perform diverse functions. The catalytic subunits are members of family B, which are distinguished by their larger sizes due to inserts in their N- and C-terminal regions. The sizes of these inserts vary among the three polymerases, and their functions remain largely unknown. Strikingly, the quaternary structures of Pol α, Pol δ, and Pol ε are arranged similarly. The catalytic subunits adopt a globular structure that is linked via its conserved C-terminal region to the B subunit. The remaining subunits are linked to the catalytic and B subunits in a highly flexible manner.

  6. Eukaryotic DNA Replicases

    KAUST Repository

    Zaher, Manal S.

    2014-11-21

    The current model of the eukaryotic DNA replication fork includes three replicative DNA polymerases, polymerase α/primase complex (Pol α), polymerase δ (Pol δ), and polymerase ε (Pol ε). The primase synthesizes 8–12 nucleotide RNA primers that are extended by the DNA polymerization activity of Pol α into 30–35 nucleotide RNA-DNA primers. Replication factor C (RFC) opens the polymerase clamp-like processivity factor, proliferating cell nuclear antigen (PCNA), and loads it onto the primer-template. Pol δ utilizes PCNA to mediate highly processive DNA synthesis, while Pol ε has intrinsic high processivity that is modestly stimulated by PCNA. Pol ε replicates the leading strand and Pol δ replicates the lagging strand in a division of labor that is not strict. The three polymerases are comprised of multiple subunits and share unifying features in their large catalytic and B subunits. The remaining subunits are evolutionarily not related and perform diverse functions. The catalytic subunits are members of family B, which are distinguished by their larger sizes due to inserts in their N- and C-terminal regions. The sizes of these inserts vary among the three polymerases, and their functions remain largely unknown. Strikingly, the quaternary structures of Pol α, Pol δ, and Pol ε are arranged similarly. The catalytic subunits adopt a globular structure that is linked via its conserved C-terminal region to the B subunit. The remaining subunits are linked to the catalytic and B subunits in a highly flexible manner.

  7. [Parasites and cancer: is there a causal link?

    Science.gov (United States)

    Cheeseman, Kevin; Certad, Gabriela; Weitzman, Jonathan B

    2016-10-01

    Over 20 % of cancers have infectious origins, including well-known examples of microbes such as viruses (HPV, EBV) and bacteria (H. pylori). The contribution of intracellular eukaryotic parasites to cancer etiology is largely unexplored. Epidemiological and clinical reports indicate that eukaryotic protozoan, such as intracellular apicomplexan that cause diseases of medical or economic importance, can be linked to various cancers: Theileria and Cryptosporidium induce host cell transformation while Plasmodium was linked epidemiologically to the "African lymphoma belt" over fifty years ago. These intracellular eukaryotic parasites hijack cellular pathways to manipulate the host cell epigenome, cellular machinery, signaling pathways and epigenetic programs and marks, such as methylation and acetylation, for their own benefit. In doing so, they tinker with the same pathways as those deregulated during cancer onset. Here we discuss how epidemiological evidence linking eukaryotic intracellular parasites to cancer onset are further strengthened by recent mechanistic studies in three apicomplexan parasites. © 2016 médecine/sciences – Inserm.

  8. Mitochondrial uncoupling proteins in unicellular eukaryotes.

    Science.gov (United States)

    Jarmuszkiewicz, Wieslawa; Woyda-Ploszczyca, Andrzej; Antos-Krzeminska, Nina; Sluse, Francis E

    2010-01-01

    Uncoupling proteins (UCPs) are members of the mitochondrial anion carrier protein family that are present in the mitochondrial inner membrane and mediate free fatty acid (FFA)-activated, purine nucleotide (PN)-inhibited proton conductance. Since 1999, the presence of UCPs has been demonstrated in some non-photosynthesising unicellular eukaryotes, including amoeboid and parasite protists, as well as in non-fermentative yeast and filamentous fungi. In the mitochondria of these organisms, UCP activity is revealed upon FFA-induced, PN-inhibited stimulation of resting respiration and a decrease in membrane potential, which are accompanied by a decrease in membranous ubiquinone (Q) reduction level. UCPs in unicellular eukaryotes are able to divert energy from oxidative phosphorylation and thus compete for a proton electrochemical gradient with ATP synthase. Our recent work indicates that membranous Q is a metabolic sensor that might utilise its redox state to release the PN inhibition of UCP-mediated mitochondrial uncoupling under conditions of phosphorylation and resting respiration. The action of reduced Q (QH2) could allow higher or complete activation of UCP. As this regulatory feature was demonstrated for microorganism UCPs (A. castellanii UCP), plant and mammalian UCP1 analogues, and UCP1 in brown adipose tissue, the process could involve all UCPs. Here, we discuss the functional connection and physiological role of UCP and alternative oxidase, two main energy-dissipating systems in the plant-type mitochondrial respiratory chain of unicellular eukaryotes, including the control of cellular energy balance as well as preventive action against the production of reactive oxygen species. Copyright © 2009 Elsevier B.V. All rights reserved.

  9. Co-operative suppression of inflammatory responses in human dendritic cells by plant proanthocyanidins and products from the parasitic nematode Trichuris suis

    DEFF Research Database (Denmark)

    Williams, Andrew R; Klaver, Elsenoor J; Laan, Lisa C

    2017-01-01

    Interactions between dendritic cells (DCs) and environmental, dietary and pathogen antigens play a key role in immune homeostasis and regulation of inflammation. Dietary polyphenols such as proanthocyanidins (PAC) may reduce inflammation, and we therefore hypothesized that PAC may suppress lipopo...

  10. Peroxisomes in parasitic protists.

    Science.gov (United States)

    Gabaldón, Toni; Ginger, Michael L; Michels, Paul A M

    Representatives of all major lineages of eukaryotes contain peroxisomes with similar morphology and mode of biogenesis, indicating a monophyletic origin of the organelles within the common ancestor of all eukaryotes. Peroxisomes originated from the endoplasmic reticulum, but despite a common origin and shared morphological features, peroxisomes from different organisms show a remarkable diversity of enzyme content and the metabolic processes present can vary dependent on nutritional or developmental conditions. A common characteristic and probable evolutionary driver for the origin of the organelle is an involvement in lipid metabolism, notably H 2 O 2 -dependent fatty-acid oxidation. Subsequent evolution of the organelle in different lineages involved multiple acquisitions of metabolic processes-often involving retargeting enzymes from other cell compartments-and losses. Information about peroxisomes in protists is still scarce, but available evidence, including new bioinformatics data reported here, indicate striking diversity amongst free-living and parasitic protists from different phylogenetic supergroups. Peroxisomes in only some protists show major involvement in H 2 O 2 -dependent metabolism, as in peroxisomes of mammalian, plant and fungal cells. Compartmentalization of glycolytic and gluconeogenic enzymes inside peroxisomes is characteristic of kinetoplastids and diplonemids, where the organelles are hence called glycosomes, whereas several other excavate parasites (Giardia, Trichomonas) have lost peroxisomes. Amongst alveolates and amoebozoans patterns of peroxisome loss are more complicated. Often, a link is apparent between the niches occupied by the parasitic protists, nutrient availability, and the absence of the organelles or their presence with a specific enzymatic content. In trypanosomatids, essentiality of peroxisomes may be considered for use in anti-parasite drug discovery. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Sexual reproduction and genetic exchange in parasitic protists.

    Science.gov (United States)

    Weedall, Gareth D; Hall, Neil

    2015-02-01

    A key part of the life cycle of an organism is reproduction. For a number of important protist parasites that cause human and animal disease, their sexuality has been a topic of debate for many years. Traditionally, protists were considered to be primitive relatives of the 'higher' eukaryotes, which may have diverged prior to the evolution of sex and to reproduce by binary fission. More recent views of eukaryotic evolution suggest that sex, and meiosis, evolved early, possibly in the common ancestor of all eukaryotes. However, detecting sex in these parasites is not straightforward. Recent advances, particularly in genome sequencing technology, have allowed new insights into parasite reproduction. Here, we review the evidence on reproduction in parasitic protists. We discuss protist reproduction in the light of parasitic life cycles and routes of transmission among hosts.

  12. Glyoxalase diversity in parasitic protists.

    Science.gov (United States)

    Deponte, Marcel

    2014-04-01

    Our current knowledge of the isomerase glyoxalase I and the thioesterase glyoxalase II is based on a variety of prokaryotic and eukaryotic (model) systems with an emphasis on human glyoxalases. During the last decade, important insights on glyoxalase catalysis and structure-function relationships have also been obtained from parasitic protists. These organisms, including kinetoplastid and apicomplexan parasites, are particularly interesting, both because of their relevance as pathogens and because of their phylogenetic diversity and host-parasite co-evolution which has led to specialized organellar and metabolic adaptations. Accordingly, the glyoxalase repertoire and properties vary significantly among parasitic protists of different major eukaryotic lineages (and even between closely related organisms). For example, several protists have an insular or non-canonical glyoxalase. Furthermore, the structures and the substrate specificities of glyoxalases display drastic variations. The aim of the present review is to highlight such differences as well as similarities between the glyoxalases of parasitic protists and to emphasize the power of comparative studies for gaining insights into fundamental principles and alternative glyoxalase functions.

  13. Parasites: Water

    Science.gov (United States)

    ... Consultations, and General Public. Contact Us Parasites Home Water Language: English Español (Spanish) Recommend on Facebook Tweet Share Compartir Parasites can live in natural water sources. When outdoors, treat your water before drinking ...

  14. Social Parasites

    Science.gov (United States)

    Lopez, Miguel A.; Nguyen, HoangKim T.; Oberholzer, Michael; Hill, Kent L.

    2011-01-01

    Summary of recent advances Protozoan parasites cause tremendous human suffering worldwide, but strategies for therapeutic intervention are limited. Recent studies illustrate that the paradigm of microbes as social organisms can be brought to bear on questions about parasite biology, transmission and pathogenesis. This review discusses recent work demonstrating adaptation of social behaviors by parasitic protozoa that cause African sleeping sickness and malaria. The recognition of social behavior and cell-cell communication as a ubiquitous property of bacteria has transformed our view of microbiology, but protozoan parasites have not generally been considered in this context. Works discussed illustrate the potential for concepts of sociomicrobiology to provide insight into parasite biology and should stimulate new approaches for thinking about parasites and parasite-host interactions. PMID:22020108

  15. Functions of myosin motors tailored for parasitism

    DEFF Research Database (Denmark)

    Mueller, Christina; Graindorge, Arnault; Soldati-Favre, Dominique

    2017-01-01

    Myosin motors are one of the largest protein families in eukaryotes that exhibit divergent cellular functions. Their roles in protozoans, a diverse group of anciently diverged, single celled organisms with many prominent members known to be parasitic and to cause diseases in human and livestock......, are largely unknown. In the recent years many different approaches, among them whole genome sequencing, phylogenetic analyses and functional studies have increased our understanding on the distribution, protein architecture and function of unconventional myosin motors in protozoan parasites. In Apicomplexa......, myosins turn out to be highly specialized and to exhibit unique functions tailored to accommodate the lifestyle of these parasites....

  16. Diversity and distribution of eukaryotic microbes in and around a brine pool adjacent to the Thuwal cold seeps in the Red Sea

    KAUST Repository

    Wang, Yong; Zhang, Wei Peng; Cao, Hui Luo; Shek, Chun Shum; Tian, Ren Mao; Wong, Yue Him; Batang, Zenon B.; Al-Suwailem, Abdulaziz M.; Qian, Pei-Yuan

    2014-01-01

    abundant species highly similar to invertebrate gregarine parasites identified in different oxygen-depleted sediments. Therefore, the present findings support the uniqueness of some microbial eukaryotic groups in this cold seep brine system. 2014 Wang

  17. Parasitism and the biodiversity-functioning relationship

    Science.gov (United States)

    Frainer, André; McKie, Brendan G.; Amundsen, Per-Arne; Knudsen, Rune; Lafferty, Kevin D.

    2018-01-01

    Biodiversity affects ecosystem functioning.Biodiversity may decrease or increase parasitism.Parasites impair individual hosts and affect their role in the ecosystem.Parasitism, in common with competition, facilitation, and predation, could regulate BD-EF relationships.Parasitism affects host phenotypes, including changes to host morphology, behavior, and physiology, which might increase intra- and interspecific functional diversity.The effects of parasitism on host abundance and phenotypes, and on interactions between hosts and the remaining community, all have potential to alter community structure and BD-EF relationships.Global change could facilitate the spread of invasive parasites, and alter the existing dynamics between parasites, communities, and ecosystems.Species interactions can influence ecosystem functioning by enhancing or suppressing the activities of species that drive ecosystem processes, or by causing changes in biodiversity. However, one important class of species interactions – parasitism – has been little considered in biodiversity and ecosystem functioning (BD-EF) research. Parasites might increase or decrease ecosystem processes by reducing host abundance. Parasites could also increase trait diversity by suppressing dominant species or by increasing within-host trait diversity. These different mechanisms by which parasites might affect ecosystem function pose challenges in predicting their net effects. Nonetheless, given the ubiquity of parasites, we propose that parasite–host interactions should be incorporated into the BD-EF framework.

  18. Fish parasites

    DEFF Research Database (Denmark)

    This book contains 22 chapters on some of the most important parasitic diseases in wild and farmed fish. International experts give updated reviews and provide solutions to the problems......This book contains 22 chapters on some of the most important parasitic diseases in wild and farmed fish. International experts give updated reviews and provide solutions to the problems...

  19. Parasitic diseases

    International Nuclear Information System (INIS)

    Rozenshtraukh, L.S.

    1983-01-01

    Foundations of roentgenological semiotics of parasitic diseases of lungs, w hich are of the greatest practical value, are presented. Roentgenological pictu res of the following parasitic diseases: hydatid and alveolar echinococcosis, pa ragonimiasis, toxoplasmosis, ascariasis, amebiasis, bilharziasis (Schistosomias is) of lungs, are considered

  20. Gonococcal attachment to eukaryotic cells

    International Nuclear Information System (INIS)

    James, J.F.; Lammel, C.J.; Draper, D.L.; Brown, D.A.; Sweet, R.L.; Brooks, G.F.

    1983-01-01

    The attachment of Neisseria gonorrhoeae to eukaryotic cells grown in tissue culture was analyzed by use of light and electron microscopy and by labeling of the bacteria with [ 3 H]- and [ 14 C]adenine. Isogenic piliated and nonpiliated N. gonorrhoeae from opaque and transparent colonies were studied. The results of light microscopy studies showed that the gonococci attached to cells of human origin, including Flow 2000, HeLa 229, and HEp 2. Studies using radiolabeled gonococci gave comparable results. Piliated N. gonorrhoeae usually attached in larger numbers than nonpiliated organisms, and those from opaque colonies attached more often than isogenic variants from transparent colonies. Day-to-day variation in rate of attachment was observed. Scanning electron microscopy studies showed the gonococcal attachment to be specific for microvilli of the host cells. It is concluded that more N. gonorrhoeae from opaque colonies, as compared with isogenic variants from transparent colonies, attach to eukaryotic cells grown in tissue culture

  1. Defensins: antifungal lessons from eukaryotes

    Directory of Open Access Journals (Sweden)

    Patrícia M. Silva

    2014-03-01

    Full Text Available Over the last years, antimicrobial peptides (AMPs have been the focus of intense research towards the finding of a viable alternative to current antifungal drugs. Defensins are one of the major families of AMPs and the most represented among all eukaryotic groups, providing an important first line of host defense against pathogenic microorganisms. Several of these cysteine-stabilized peptides present a relevant effect against fungi. Defensins are the AMPs with the broader distribution across all eukaryotic kingdoms, namely, Fungi, Plantæ and Animalia, and were recently shown to have an ancestor in a bacterial organism. As a part of the host defense, defensins act as an important vehicle of information between innate and adaptive immune system and have a role in immunomodulation. This multidimensionality represents a powerful host shield, hard for microorganisms to overcome using single approach resistance strategies. Pathogenic fungi resistance to conventional antimycotic drugs is becoming a major problem. Defensins, as other AMPs, have shown to be an effective alternative to the current antimycotic therapies, demonstrating potential as novel therapeutic agents or drug leads. In this review, we summarize the current knowledge on some eukaryotic defensins with antifungal action. An overview of the main targets in the fungal cell and the mechanism of action of these AMPs (namely, the selectivity for some fungal membrane components are presented. Additionally, recent works on antifungal defensins structure, activity and citotoxicity are also reviewed.

  2. Parasites and chronic renal failure

    OpenAIRE

    Mohammadi Manesh, Reza; Hosseini Safa, Ahmad; Sharafi, Seyedeh Maryam; Jafari, Rasool; Bahadoran, Mehran; Yousefi, Morteza; Nasri, Hamid; Yousofi Darani, Hossein

    2014-01-01

    Suppression of the human immune system results in an increase in susceptibility to infection by various infectious agents. Conditions such as AIDS, organ transplantation and chronic renal insufficiency (CRI) are the most important cause of insufficient immune response against infections. Long term renal disorders result in uremia, which can suppress human immune system. Parasitic infections are one of the most important factors indicating the public health problems of the societies. These inf...

  3. The revised classification of eukaryotes

    Czech Academy of Sciences Publication Activity Database

    Adl, S.; Simpson, A. G. B.; Lane, C. E.; Lukeš, Julius; Bass, D.; Bowser, S. S.; Brown, M W.; Burki, F.; Dunthorn, M.; Hampl, V.; Heiss, A.; Hoppenrath, M.; Lara, E.; Gall, L. L.; Lynn, D. H.; McManus, H.; Mitchell, E. A. D.; Mozley-Stanridge, S. E.; Parfrey, L. W.; Pawlowski, J.; Rueckert, S.; Shadwick, L.; Schoch, C.L.; Smirnov, A.; Spiegel, F. W.

    2012-01-01

    Roč. 59, č. 5 (2012), s. 429-514 ISSN 1066-5234 Institutional support: RVO:60077344 Keywords : Algae * amoebae * biodiversity * ciliates * flagellates * fungi * parasites * protozoa * systematics * taxonomy Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.162, year: 2012 http://onlinelibrary.wiley.com/doi/10.1111/j.1550-7408.2012.00644.x/pdf

  4. The adaptive significance of inquiline parasite workers

    DEFF Research Database (Denmark)

    Sumner, Seirian; Nash, David R; Boomsma, Jacobus J

    2003-01-01

    Social parasites exploit the socially managed resources of their host's society. Inquiline social parasites are dependent on their host throughout their life cycle, and so many of the traits inherited from their free-living ancestor are removed by natural selection. One trait that is commonly lost...... is the worker caste, the functions of which are adequately fulfilled by host workers. The few inquiline parasites that have retained a worker caste are thought to be at a transitional stage in the evolution of social parasitism, and their worker castes are considered vestigial and non-adaptive. However...... a vital role in ensuring the parasite's fitness. We show that the presence of these parasite workers has a positive effect on the production of parasite sexuals and a negative effect on the production of host sexuals. This suggests that inquiline workers play a vital role in suppressing host queen...

  5. Diversity of Eukaryotic Translational Initiation Factor eIF4E in Protists.

    Science.gov (United States)

    Jagus, Rosemary; Bachvaroff, Tsvetan R; Joshi, Bhavesh; Place, Allen R

    2012-01-01

    The greatest diversity of eukaryotic species is within the microbial eukaryotes, the protists, with plants and fungi/metazoa representing just two of the estimated seventy five lineages of eukaryotes. Protists are a diverse group characterized by unusual genome features and a wide range of genome sizes from 8.2 Mb in the apicomplexan parasite Babesia bovis to 112,000-220,050 Mb in the dinoflagellate Prorocentrum micans. Protists possess numerous cellular, molecular and biochemical traits not observed in "text-book" model organisms. These features challenge some of the concepts and assumptions about the regulation of gene expression in eukaryotes. Like multicellular eukaryotes, many protists encode multiple eIF4Es, but few functional studies have been undertaken except in parasitic species. An earlier phylogenetic analysis of protist eIF4Es indicated that they cannot be grouped within the three classes that describe eIF4E family members from multicellular organisms. Many more protist sequences are now available from which three clades can be recognized that are distinct from the plant/fungi/metazoan classes. Understanding of the protist eIF4Es will be facilitated as more sequences become available particularly for the under-represented opisthokonts and amoebozoa. Similarly, a better understanding of eIF4Es within each clade will develop as more functional studies of protist eIF4Es are completed.

  6. Update on pathology of ocular parasitic disease.

    Science.gov (United States)

    Das, Dipankar; Ramachandra, Varsha; Islam, Saidul; Bhattacharjee, Harsha; Biswas, Jyotirmay; Koul, Akanksha; Deka, Panna; Deka, Apurba

    2016-11-01

    Parasites are a group of eukaryotic organisms that may be free-living or form a symbiotic or parasitic relationship with the hosts. Consisting of over 800,000 recognized species, parasites may be unicellular (Protozoa) or multicellular (helminths and arthropods). The association of parasites with human population started long before the emergence of civilization. Parasitic zoonotic diseases are prevalent worldwide including India. Appropriate epidemiological data are lacking on existing zoonotic parasitic diseases, and newer diseases are emerging in our scenario. Systemic diseases such as cysticercosis, paragonimiasis, hydatidosis, and toxoplasmosis are fairly common. Acquired Toxoplasma infections are rising in immune-deficient individuals. Amongst the ocular parasitic diseases, various protozoas such as Cystoidea, trematodes, tissue flagellates, sporozoas etc. affect humans in general and eyes in particular, in different parts of the world. These zoonoses seem to be a real health related problem globally. Recent intensification of research throughout the world has led to specialization in biological fields, creating a conducive situation for researchers interested in this subject. The basics of parasitology lie in morphology, pathology, and with recent updates in molecular parasitology, the scope has extended further. The current review is to address the recent update in ophthalmic parasites with special reference to pathology and give a glimpse of further research in this field.

  7. Update on pathology of ocular parasitic disease

    Directory of Open Access Journals (Sweden)

    Dipankar Das

    2016-01-01

    Full Text Available Parasites are a group of eukaryotic organisms that may be free-living or form a symbiotic or parasitic relationship with the hosts. Consisting of over 800,000 recognized species, parasites may be unicellular (Protozoa or multicellular (helminths and arthropods. The association of parasites with human population started long before the emergence of civilization. Parasitic zoonotic diseases are prevalent worldwide including India. Appropriate epidemiological data are lacking on existing zoonotic parasitic diseases, and newer diseases are emerging in our scenario. Systemic diseases such as cysticercosis, paragonimiasis, hydatidosis, and toxoplasmosis are fairly common. Acquired Toxoplasma infections are rising in immune-deficient individuals. Amongst the ocular parasitic diseases, various protozoas such as Cystoidea, trematodes, tissue flagellates, sporozoas etc. affect humans in general and eyes in particular, in different parts of the world. These zoonoses seem to be a real health related problem globally. Recent intensification of research throughout the world has led to specialization in biological fields, creating a conducive situation for researchers interested in this subject. The basics of parasitology lie in morphology, pathology, and with recent updates in molecular parasitology, the scope has extended further. The current review is to address the recent update in ophthalmic parasites with special reference to pathology and give a glimpse of further research in this field.

  8. Regulation of Gene Expression in Protozoa Parasites

    Directory of Open Access Journals (Sweden)

    Consuelo Gomez

    2010-01-01

    Full Text Available Infections with protozoa parasites are associated with high burdens of morbidity and mortality across the developing world. Despite extensive efforts to control the transmission of these parasites, the spread of populations resistant to drugs and the lack of effective vaccines against them contribute to their persistence as major public health problems. Parasites should perform a strict control on the expression of genes involved in their pathogenicity, differentiation, immune evasion, or drug resistance, and the comprehension of the mechanisms implicated in that control could help to develop novel therapeutic strategies. However, until now these mechanisms are poorly understood in protozoa. Recent investigations into gene expression in protozoa parasites suggest that they possess many of the canonical machineries employed by higher eukaryotes for the control of gene expression at transcriptional, posttranscriptional, and epigenetic levels, but they also contain exclusive mechanisms. Here, we review the current understanding about the regulation of gene expression in Plasmodium sp., Trypanosomatids, Entamoeba histolytica and Trichomonas vaginalis.

  9. Regulation of gene expression in protozoa parasites.

    Science.gov (United States)

    Gomez, Consuelo; Esther Ramirez, M; Calixto-Galvez, Mercedes; Medel, Olivia; Rodríguez, Mario A

    2010-01-01

    Infections with protozoa parasites are associated with high burdens of morbidity and mortality across the developing world. Despite extensive efforts to control the transmission of these parasites, the spread of populations resistant to drugs and the lack of effective vaccines against them contribute to their persistence as major public health problems. Parasites should perform a strict control on the expression of genes involved in their pathogenicity, differentiation, immune evasion, or drug resistance, and the comprehension of the mechanisms implicated in that control could help to develop novel therapeutic strategies. However, until now these mechanisms are poorly understood in protozoa. Recent investigations into gene expression in protozoa parasites suggest that they possess many of the canonical machineries employed by higher eukaryotes for the control of gene expression at transcriptional, posttranscriptional, and epigenetic levels, but they also contain exclusive mechanisms. Here, we review the current understanding about the regulation of gene expression in Plasmodium sp., Trypanosomatids, Entamoeba histolytica and Trichomonas vaginalis.

  10. Parasitic Apologies

    Science.gov (United States)

    Galatolo, Renata; Ursi, Biagio; Bongelli, Ramona

    2016-01-01

    The action of apologizing can be accomplished as the main business of the interaction or incidentally while participants are doing something else. We refer to these apologies as "parasitic apologies," because they are produced "en passant" (Schegloff, 2007), and focus our analysis on this type of apology occurring at the…

  11. Genome-wide mapping reveals single-origin chromosome replication in Leishmania, a eukaryotic microbe.

    Science.gov (United States)

    Marques, Catarina A; Dickens, Nicholas J; Paape, Daniel; Campbell, Samantha J; McCulloch, Richard

    2015-10-19

    DNA replication initiates on defined genome sites, termed origins. Origin usage appears to follow common rules in the eukaryotic organisms examined to date: all chromosomes are replicated from multiple origins, which display variations in firing efficiency and are selected from a larger pool of potential origins. To ask if these features of DNA replication are true of all eukaryotes, we describe genome-wide origin mapping in the parasite Leishmania. Origin mapping in Leishmania suggests a striking divergence in origin usage relative to characterized eukaryotes, since each chromosome appears to be replicated from a single origin. By comparing two species of Leishmania, we find evidence that such origin singularity is maintained in the face of chromosome fusion or fission events during evolution. Mapping Leishmania origins suggests that all origins fire with equal efficiency, and that the genomic sites occupied by origins differ from related non-origins sites. Finally, we provide evidence that origin location in Leishmania displays striking conservation with Trypanosoma brucei, despite the latter parasite replicating its chromosomes from multiple, variable strength origins. The demonstration of chromosome replication for a single origin in Leishmania, a microbial eukaryote, has implications for the evolution of origin multiplicity and associated controls, and may explain the pervasive aneuploidy that characterizes Leishmania chromosome architecture.

  12. Repair of DNA DSB in higher eukaryotes

    International Nuclear Information System (INIS)

    Wang, H.; Perrault, A.R.; Takeda, Y.; Iliakis, G.

    2003-01-01

    Cells of higher eukaryotes process within minutes double strand breaks (DSBs) in their genome using a NHEJ apparatus that engages DNA-PKcs, Ku, DNA ligase IV, XRCC4, and other as of yet unidentified factors. Although chemical inhibition, or mutation, in any of these factors delays processing, cells ultimately remove the majority of DNA DSBs using an alternative pathway operating with slower kinetics. This alternative pathway is active in mutants deficient in genes of the RAD52 epistasis group. We proposed, therefore, that it reflects an alternative form of NHEJ that operates as a backup (B-NHEJ) to the DNA-PK- dependent (D-NHEJ) pathway, rather than homology directed repair of DSBs. We studied the role of Ku and DNA-PKcs in the coordination of these pathways using as a model end joining of restriction endonuclease linearized plasmid DNA in whole cell extracts. Efficient error-free endjoining observed in such in-vitro reactions is strongly inhibited by anti-Ku antibodies. The inhibition requires DNA-PKcs, despite that fact that Ku efficiently binds DNA ends in the presence of antibodies, or in the absence of DNA-PKcs. Strong inhibition of DNA endjoining is also mediated by wortmannin, an inhibitor of DNA-PKcs, in the presence but not in the absence of Ku, and this inhibition can be rescued by pre-incubating the reaction with double stranded oligonucleotides. The results are compatible with a role of Ku in directing endjoining to a DNA-PK dependent pathway, mediated by efficient end binding and productive interactions with DNA-PKcs. On the other hand, efficient end joining is observed in extracts of cells lacking DNA-PKcs, as well as in Ku-depleted extracts sugggesting the operation of alternative pathways. Extracts depleted of Ku and DNA-PKcs rejoin blunt ends, as well as homologous ends with 3' or 5' protruding single strands with similar efficiency, but addition of Ku suppresses joining of blunt ends and homologous ends with 3' overhangs. We propose that the

  13. Origin and evolution of SINEs in eukaryotic genomes.

    Science.gov (United States)

    Kramerov, D A; Vassetzky, N S

    2011-12-01

    Short interspersed elements (SINEs) are one of the two most prolific mobile genomic elements in most of the higher eukaryotes. Although their biology is still not thoroughly understood, unusual life cycle of these simple elements amplified as genomic parasites makes their evolution unique in many ways. In contrast to most genetic elements including other transposons, SINEs emerged de novo many times in evolution from available molecules (for example, tRNA). The involvement of reverse transcription in their amplification cycle, huge number of genomic copies and modular structure allow variation mechanisms in SINEs uncommon or rare in other genetic elements (module exchange between SINE families, dimerization, and so on.). Overall, SINE evolution includes their emergence, progressive optimization and counteraction to the cell's defense against mobile genetic elements.

  14. How natural a kind is "eukaryote?".

    Science.gov (United States)

    Doolittle, W Ford

    2014-06-02

    Systematics balances uneasily between realism and nominalism, uncommitted as to whether biological taxa are discoveries or inventions. If the former, they might be taken as natural kinds. I briefly review some philosophers' concepts of natural kinds and then argue that several of these apply well enough to "eukaryote." Although there are some sticky issues around genomic chimerism and when eukaryotes first appeared, if we allow for degrees in the naturalness of kinds, existing eukaryotes rank highly, higher than prokaryotes. Most biologists feel this intuitively: All I attempt to do here is provide some conceptual justification. Copyright © 2014 Cold Spring Harbor Laboratory Press; all rights reserved.

  15. Arabinogalactan proteins have deep roots in eukaryotes

    DEFF Research Database (Denmark)

    Hervé, Cécile; Siméon, Amandine; Jam, Murielle

    2016-01-01

    Arabinogalactan proteins (AGPs) are highly glycosylated, hydroxyproline-rich proteins found at the cell surface of plants, where they play key roles in developmental processes. Brown algae are marine, multicellular, photosynthetic eukaryotes. They belong to the phylum Stramenopiles, which...

  16. One Health: parasites and beyond.

    Science.gov (United States)

    Blake, Damer P; Betson, Martha

    2017-01-01

    The field of parasitism is broad, encompassing relationships between organisms where one benefits at the expense of another. Traditionally the discipline focuses on eukaryotes, with the study of bacteria and viruses complementary but distinct. Nonetheless, parasites vary in size and complexity from single celled protozoa, to enormous plants like those in the genus Rafflesia. Lifecycles range from obligate intracellular to extensive exoparasitism. Examples of parasites include high-profile medical and zoonotic pathogens such as Plasmodium, veterinary pathogens of wild and captive animals and many of the agents which cause neglected tropical diseases, stretching to parasites which infect plants and other parasites (e.g. Kikuchi et al. 2011; Hotez et al. 2014; Blake et al. 2015; Hemingway, 2015; Meekums et al. 2015; Sandlund et al. 2015). The breadth of parasitology has been matched by the variety of ways in which parasites are studied, drawing upon biological, chemical, molecular, epidemiological and other expertise. Despite such breadth bridging between disciplines has commonly been problematic, regardless of extensive encouragement from government agencies, peer audiences and funding bodies promoting multidisciplinary research. Now, progress in understanding and collaboration can benefit from establishment of the One Health concept (Zinsstag et al. 2012; Stark et al. 2015). One Health draws upon biological, environmental, medical, veterinary and social science disciplines in order to improve human, animal and environmental health, although it remains tantalizingly difficult to engage many relevant parties. For infectious diseases traditional divides have been exacerbated as the importance of wildlife reservoirs, climate change, food production systems and socio-economic diversity have been recognized but often not addressed in a multidisciplinary manner. In response the 2015 Autumn Symposium organized by the British Society for Parasitology (BSP; https

  17. Transfer of DNA from Bacteria to Eukaryotes

    Directory of Open Access Journals (Sweden)

    Benoît Lacroix

    2016-07-01

    Full Text Available Historically, the members of the Agrobacterium genus have been considered the only bacterial species naturally able to transfer and integrate DNA into the genomes of their eukaryotic hosts. Yet, increasing evidence suggests that this ability to genetically transform eukaryotic host cells might be more widespread in the bacterial world. Indeed, analyses of accumulating genomic data reveal cases of horizontal gene transfer from bacteria to eukaryotes and suggest that it represents a significant force in adaptive evolution of eukaryotic species. Specifically, recent reports indicate that bacteria other than Agrobacterium, such as Bartonella henselae (a zoonotic pathogen, Rhizobium etli (a plant-symbiotic bacterium related to Agrobacterium, or even Escherichia coli, have the ability to genetically transform their host cells under laboratory conditions. This DNA transfer relies on type IV secretion systems (T4SSs, the molecular machines that transport macromolecules during conjugative plasmid transfer and also during transport of proteins and/or DNA to the eukaryotic recipient cells. In this review article, we explore the extent of possible transfer of genetic information from bacteria to eukaryotic cells as well as the evolutionary implications and potential applications of this transfer.

  18. Enhanced Transmission of Drug-Resistant Parasites to Mosquitoes following Drug Treatment in Rodent Malaria

    OpenAIRE

    Bell, Andrew S.; Huijben, Silvie; Paaijmans, Krijn P.; Sim, Derek G.; Chan, Brian H. K.; Nelson, William A.; Read, Andrew F.

    2012-01-01

    The evolution of drug resistant Plasmodium parasites is a major challenge to effective malaria control. In theory, competitive interactions between sensitive parasites and resistant parasites within infections are a major determinant of the rate at which parasite evolution undermines drug efficacy. Competitive suppression of resistant parasites in untreated hosts slows the spread of resistance; competitive release following treatment enhances it. Here we report that for the murine model Plasm...

  19. Are all red algal parasites cut from the same cloth?

    Directory of Open Access Journals (Sweden)

    Eric D. Salomaki

    2014-12-01

    Full Text Available Parasitism is a common life strategy throughout the eukaryotic tree of life. Many devastating human pathogens, including the causative agents of malaria and toxoplasmosis, have evolved from a photosynthetic ancestor. However, how an organism transitions from a photosynthetic to a parasitic life history strategy remains mostly unknown. This is largely because few systems present the opportunity to make meaningful comparisons between a parasite and a close free-living relative. Parasites have independently evolved dozens of times throughout the Florideophyceae (Rhodophyta, and often infect close relatives. The accepted evolutionary paradigm proposes that red algal parasites arise by first infecting a close relative and over time diversify and infect more distantly related species. This provides a natural evolutionary gradient of relationships between hosts and parasites that share a photosynthetic common ancestor. Elegant microscopic work in the late 20th century provided detailed insight into the infection cycle of red algal parasites and the cellular interactions between parasites and their hosts. Those studies led to the use of molecular work to further investigate the origins of the parasite organelles and reveal the evolutionary relationships between hosts and their parasites. Here we synthesize the research detailing the infection methods and cellular interactions between red algal parasites and their hosts. We offer an alternative hypothesis to the current dogma of red algal parasite evolution and propose that red algae can adopt a parasitic life strategy through multiple evolutionary pathways, including direct infection of distant relatives. Furthermore, we highlight potential directions for future research to further evaluate parasite evolution in red algae.

  20. Parasitic diseases of lungs

    International Nuclear Information System (INIS)

    Rozenshtraukh, L.C.; Rybakova, N.I.; Vinner, M.G.

    1987-01-01

    Roentgenologic semiotics of the main parasitic diseases of lungs is described: echinococcosis, paragonimiasis, cysticercosis, toxoplasmosis, ascariasis, amebiosis and some rarely met parasitic diseases

  1. Introns Protect Eukaryotic Genomes from Transcription-Associated Genetic Instability.

    Science.gov (United States)

    Bonnet, Amandine; Grosso, Ana R; Elkaoutari, Abdessamad; Coleno, Emeline; Presle, Adrien; Sridhara, Sreerama C; Janbon, Guilhem; Géli, Vincent; de Almeida, Sérgio F; Palancade, Benoit

    2017-08-17

    Transcription is a source of genetic instability that can notably result from the formation of genotoxic DNA:RNA hybrids, or R-loops, between the nascent mRNA and its template. Here we report an unexpected function for introns in counteracting R-loop accumulation in eukaryotic genomes. Deletion of endogenous introns increases R-loop formation, while insertion of an intron into an intronless gene suppresses R-loop accumulation and its deleterious impact on transcription and recombination in yeast. Recruitment of the spliceosome onto the mRNA, but not splicing per se, is shown to be critical to attenuate R-loop formation and transcription-associated genetic instability. Genome-wide analyses in a number of distant species differing in their intron content, including human, further revealed that intron-containing genes and the intron-richest genomes are best protected against R-loop accumulation and subsequent genetic instability. Our results thereby provide a possible rationale for the conservation of introns throughout the eukaryotic lineage. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Atypical mitochondrial inheritance patterns in eukaryotes.

    Science.gov (United States)

    Breton, Sophie; Stewart, Donald T

    2015-10-01

    Mitochondrial DNA (mtDNA) is predominantly maternally inherited in eukaryotes. Diverse molecular mechanisms underlying the phenomenon of strict maternal inheritance (SMI) of mtDNA have been described, but the evolutionary forces responsible for its predominance in eukaryotes remain to be elucidated. Exceptions to SMI have been reported in diverse eukaryotic taxa, leading to the prediction that several distinct molecular mechanisms controlling mtDNA transmission are present among the eukaryotes. We propose that these mechanisms will be better understood by studying the deviations from the predominating pattern of SMI. This minireview summarizes studies on eukaryote species with unusual or rare mitochondrial inheritance patterns, i.e., other than the predominant SMI pattern, such as maternal inheritance of stable heteroplasmy, paternal leakage of mtDNA, biparental and strictly paternal inheritance, and doubly uniparental inheritance of mtDNA. The potential genes and mechanisms involved in controlling mitochondrial inheritance in these organisms are discussed. The linkage between mitochondrial inheritance and sex determination is also discussed, given that the atypical systems of mtDNA inheritance examined in this minireview are frequently found in organisms with uncommon sexual systems such as gynodioecy, monoecy, or andromonoecy. The potential of deviations from SMI for facilitating a better understanding of a number of fundamental questions in biology, such as the evolution of mtDNA inheritance, the coevolution of nuclear and mitochondrial genomes, and, perhaps, the role of mitochondria in sex determination, is considerable.

  3. Comparative genomics and evolution of eukaryotic phospholipidbiosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Lykidis, Athanasios

    2006-12-01

    Phospholipid biosynthetic enzymes produce diverse molecular structures and are often present in multiple forms encoded by different genes. This work utilizes comparative genomics and phylogenetics for exploring the distribution, structure and evolution of phospholipid biosynthetic genes and pathways in 26 eukaryotic genomes. Although the basic structure of the pathways was formed early in eukaryotic evolution, the emerging picture indicates that individual enzyme families followed unique evolutionary courses. For example, choline and ethanolamine kinases and cytidylyltransferases emerged in ancestral eukaryotes, whereas, multiple forms of the corresponding phosphatidyltransferases evolved mainly in a lineage specific manner. Furthermore, several unicellular eukaryotes maintain bacterial-type enzymes and reactions for the synthesis of phosphatidylglycerol and cardiolipin. Also, base-exchange phosphatidylserine synthases are widespread and ancestral enzymes. The multiplicity of phospholipid biosynthetic enzymes has been largely generated by gene expansion in a lineage specific manner. Thus, these observations suggest that phospholipid biosynthesis has been an actively evolving system. Finally, comparative genomic analysis indicates the existence of novel phosphatidyltransferases and provides a candidate for the uncharacterized eukaryotic phosphatidylglycerol phosphate phosphatase.

  4. Translational Control in Plasmodium and Toxoplasma Parasites

    Science.gov (United States)

    Joyce, Bradley R.; Sullivan, William J.; Nussenzweig, Victor

    2013-01-01

    The life cycles of apicomplexan parasites such as Plasmodium spp. and Toxoplasma gondii are complex, consisting of proliferative and latent stages within multiple hosts. Dramatic transformations take place during the cycles, and they demand precise control of gene expression at all levels, including translation. This review focuses on the mechanisms that regulate translational control in Plasmodium and Toxoplasma, with a particular emphasis on the phosphorylation of the α subunit of eukaryotic translation initiation factor 2 (eIF2α). Phosphorylation of eIF2α (eIF2α∼P) is a conserved mechanism that eukaryotic cells use to repress global protein synthesis while enhancing gene-specific translation of a subset of mRNAs. Elevated levels of eIF2α∼P have been observed during latent stages in both Toxoplasma and Plasmodium, indicating that translational control plays a role in maintaining dormancy. Parasite-specific eIF2α kinases and phosphatases are also required for proper developmental transitions and adaptation to cellular stresses encountered during the life cycle. Identification of small-molecule inhibitors of apicomplexan eIF2α kinases may selectively interfere with parasite translational control and lead to the development of new therapies to treat malaria and toxoplasmosis. PMID:23243065

  5. Translational control in Plasmodium and toxoplasma parasites.

    Science.gov (United States)

    Zhang, Min; Joyce, Bradley R; Sullivan, William J; Nussenzweig, Victor

    2013-02-01

    The life cycles of apicomplexan parasites such as Plasmodium spp. and Toxoplasma gondii are complex, consisting of proliferative and latent stages within multiple hosts. Dramatic transformations take place during the cycles, and they demand precise control of gene expression at all levels, including translation. This review focuses on the mechanisms that regulate translational control in Plasmodium and Toxoplasma, with a particular emphasis on the phosphorylation of the α subunit of eukaryotic translation initiation factor 2 (eIF2α). Phosphorylation of eIF2α (eIF2α∼P) is a conserved mechanism that eukaryotic cells use to repress global protein synthesis while enhancing gene-specific translation of a subset of mRNAs. Elevated levels of eIF2α∼P have been observed during latent stages in both Toxoplasma and Plasmodium, indicating that translational control plays a role in maintaining dormancy. Parasite-specific eIF2α kinases and phosphatases are also required for proper developmental transitions and adaptation to cellular stresses encountered during the life cycle. Identification of small-molecule inhibitors of apicomplexan eIF2α kinases may selectively interfere with parasite translational control and lead to the development of new therapies to treat malaria and toxoplasmosis.

  6. Eukaryotes first: how could that be?

    Science.gov (United States)

    Mariscal, Carlos; Doolittle, W Ford

    2015-09-26

    In the half century since the formulation of the prokaryote : eukaryote dichotomy, many authors have proposed that the former evolved from something resembling the latter, in defiance of common (and possibly common sense) views. In such 'eukaryotes first' (EF) scenarios, the last universal common ancestor is imagined to have possessed significantly many of the complex characteristics of contemporary eukaryotes, as relics of an earlier 'progenotic' period or RNA world. Bacteria and Archaea thus must have lost these complex features secondarily, through 'streamlining'. If the canonical three-domain tree in which Archaea and Eukarya are sisters is accepted, EF entails that Bacteria and Archaea are convergently prokaryotic. We ask what this means and how it might be tested. © 2015 The Author(s).

  7. DETECTION OF PROTOZOAN PARASITES IN SOURCE AND FINISHED WATER - 3RD EDITION ASM'S METHODS IN ENVIRONMENTAL MICROBIOLOGY

    Science.gov (United States)

    Protozoans are eukaryotic organisms which can live either a free-living or parasitic existence. Some free-living forms, under the right conditions, can become opportunistic parasites. Enteric pathogenic protozoans, like Giardia and Cryptosporidium, which are now known to be tra...

  8. Reproduction, symbiosis, and the eukaryotic cell

    Science.gov (United States)

    Godfrey-Smith, Peter

    2015-01-01

    This paper develops a conceptual framework for addressing questions about reproduction, individuality, and the units of selection in symbiotic associations, with special attention to the origin of the eukaryotic cell. Three kinds of reproduction are distinguished, and a possible evolutionary sequence giving rise to a mitochondrion-containing eukaryotic cell from an endosymbiotic partnership is analyzed as a series of transitions between each of the three forms of reproduction. The sequence of changes seen in this “egalitarian” evolutionary transition is compared with those that apply in “fraternal” transitions, such as the evolution of multicellularity in animals. PMID:26286983

  9. Host-Parasite Interactions and Purifying Selection in a Microsporidian Parasite of Honey Bees.

    Directory of Open Access Journals (Sweden)

    Qiang Huang

    Full Text Available To clarify the mechanisms of Nosema ceranae parasitism, we deep-sequenced both honey bee host and parasite mRNAs throughout a complete 6-day infection cycle. By time-series analysis, 1122 parasite genes were significantly differently expressed during the reproduction cycle, clustering into 4 expression patterns. We found reactive mitochondrial oxygen species modulator 1 of the host to be significantly down regulated during the entire infection period. Our data support the hypothesis that apoptosis of honey bee cells was suppressed during infection. We further analyzed genome-wide genetic diversity of this parasite by comparing samples collected from the same site in 2007 and 2013. The number of SNP positions per gene and the proportion of non-synonymous substitutions per gene were significantly reduced over this time period, suggesting purifying selection on the parasite genome and supporting the hypothesis that a subset of N. ceranae strains might be dominating infection.

  10. Host-Parasite Interactions and Purifying Selection in a Microsporidian Parasite of Honey Bees.

    Science.gov (United States)

    Huang, Qiang; Chen, Yan Ping; Wang, Rui Wu; Cheng, Shang; Evans, Jay D

    2016-01-01

    To clarify the mechanisms of Nosema ceranae parasitism, we deep-sequenced both honey bee host and parasite mRNAs throughout a complete 6-day infection cycle. By time-series analysis, 1122 parasite genes were significantly differently expressed during the reproduction cycle, clustering into 4 expression patterns. We found reactive mitochondrial oxygen species modulator 1 of the host to be significantly down regulated during the entire infection period. Our data support the hypothesis that apoptosis of honey bee cells was suppressed during infection. We further analyzed genome-wide genetic diversity of this parasite by comparing samples collected from the same site in 2007 and 2013. The number of SNP positions per gene and the proportion of non-synonymous substitutions per gene were significantly reduced over this time period, suggesting purifying selection on the parasite genome and supporting the hypothesis that a subset of N. ceranae strains might be dominating infection.

  11. The origin of the eukaryotic cell

    Science.gov (United States)

    Hartman, H.

    1984-01-01

    The endosymbiotic hypothesis for the origin of the eukaryotic cell has been applied to the origin of the mitochondria and chloroplasts. However as has been pointed out by Mereschowsky in 1905, it should also be applied to the nucleus as well. If the nucleus, mitochondria and chloroplasts are endosymbionts, then it is likely that the organism that did the engulfing was not a DNA-based organism. In fact, it is useful to postulate that this organism was a primitive RNA-based organism. This hypothesis would explain the preponderance of RNA viruses found in eukaryotic cells. The centriole and basal body do not have a double membrane or DNA. Like all MTOCs (microtubule organising centres), they have a structural or morphic RNA implicated in their formation. This would argue for their origin in the early RNA-based organism rather than in an endosymbiotic event involving bacteria. Finally, the eukaryotic cell uses RNA in ways quite unlike bacteria, thus pointing to a greater emphasis of RNA in both control and structure in the cell. The origin of the eukaryotic cell may tell us why it rather than its prokaryotic relative evolved into the metazoans who are reading this paper.

  12. Eukaryotic acquisition of a bacterial operon

    Science.gov (United States)

    The yeast Saccharomyces cerevisiae is one of the champions of basic biomedical research due to its compact eukaryotic genome and ease of experimental manipulation. Despite these immense strengths, its impact on understanding the genetic basis of natural phenotypic variation has been limited by strai...

  13. Anaerobic energy metabolism in unicellular photosynthetic eukaryotes.

    Science.gov (United States)

    Atteia, Ariane; van Lis, Robert; Tielens, Aloysius G M; Martin, William F

    2013-02-01

    Anaerobic metabolic pathways allow unicellular organisms to tolerate or colonize anoxic environments. Over the past ten years, genome sequencing projects have brought a new light on the extent of anaerobic metabolism in eukaryotes. A surprising development has been that free-living unicellular algae capable of photoautotrophic lifestyle are, in terms of their enzymatic repertoire, among the best equipped eukaryotes known when it comes to anaerobic energy metabolism. Some of these algae are marine organisms, common in the oceans, others are more typically soil inhabitants. All these species are important from the ecological (O(2)/CO(2) budget), biotechnological, and evolutionary perspectives. In the unicellular algae surveyed here, mixed-acid type fermentations are widespread while anaerobic respiration, which is more typical of eukaryotic heterotrophs, appears to be rare. The presence of a core anaerobic metabolism among the algae provides insights into its evolutionary origin, which traces to the eukaryote common ancestor. The predicted fermentative enzymes often exhibit an amino acid extension at the N-terminus, suggesting that these proteins might be compartmentalized in the cell, likely in the chloroplast or the mitochondrion. The green algae Chlamydomonas reinhardtii and Chlorella NC64 have the most extended set of fermentative enzymes reported so far. Among the eukaryotes with secondary plastids, the diatom Thalassiosira pseudonana has the most pronounced anaerobic capabilities as yet. From the standpoints of genomic, transcriptomic, and biochemical studies, anaerobic energy metabolism in C. reinhardtii remains the best characterized among photosynthetic protists. This article is part of a Special Issue entitled: The evolutionary aspects of bioenergetic systems. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. The Superoxide Reductase from the Early Diverging Eukaryote Giardia Intestinalis

    International Nuclear Information System (INIS)

    Cabelli, D.E.; Testa, F.; Mastronicola, D.; Bordi, E.; Pucillo, L.P.; Sarti, P.; Saraiva, L.M.; Giuffre, A.; Teixeira, M.

    2011-01-01

    Unlike superoxide dismutases (SODs), superoxidereductases (SORs) eliminate superoxide anion (O 2 # sm b ullet# - ) not through its dismutation, but via reduction to hydrogen peroxide (H 2 O 2 ) in the presence of an electron donor. The microaerobic protist Giardia intestinalis, responsible for a common intestinal disease in humans, though lacking SOD and other canonical reactive oxygen species-detoxifying systems, is among the very few eukaryotes encoding a SOR yet identified. In this study, the recombinant SOR from Giardia (SOR Gi ) was purified and characterized by pulse radiolysis and stopped-flow spectrophotometry. The protein, isolated in the reduced state, after oxidation by superoxide or hexachloroiridate(IV), yields a resting species (T final ) with Fe 3+ ligated to glutamate or hydroxide depending on pH (apparent pK a = 8.7). Although showing negligible SOD activity, reduced SOR Gi reacts with O 2 # sm b ullet# - with a pH-independent second-order rate constant k 1 = 1.0 x 10 9 M -1 s -1 and yields the ferric-(hydro)peroxo intermediate T 1 ; this in turn rapidly decays to the T final state with pH-dependent rates, without populating other detectable intermediates. Immunoblotting assays show that SOR Gi is expressed in the disease-causing trophozoite of Giardia. We propose that the superoxide-scavenging activity of SOR in Giardia may promote the survival of this air-sensitive parasite in the fairly aerobic proximal human small intestine during infection.

  15. Molecular detection of eukaryotes in a single human stool sample from Senegal.

    Directory of Open Access Journals (Sweden)

    Ibrahim Hamad

    Full Text Available BACKGROUND: Microbial eukaryotes represent an important component of the human gut microbiome, with different beneficial or harmful roles; some species are commensal or mutualistic, whereas others are opportunistic or parasitic. The diversity of eukaryotes inhabiting humans remains relatively unexplored because of either the low abundance of these organisms in human gut or because they have received limited attention from a whole-community perspective. METHODOLOGY/PRINCIPAL FINDING: In this study, a single fecal sample from a healthy African male was studied using both culture-dependent methods and extended molecular methods targeting the 18S rRNA and ITS sequences. Our results revealed that very few fungi, including Candida spp., Galactomyces spp., and Trichosporon asahii, could be isolated using culture-based methods. In contrast, a relatively a high number of eukaryotic species could be identified in this fecal sample when culture-independent methods based on various primer sets were used. A total of 27 species from one sample were found among the 977 analyzed clones. The clone libraries were dominated by fungi (716 clones/977, 73.3%, corresponding to 16 different species. In addition, 187 sequences out of 977 (19.2% corresponded to 9 different species of plants; 59 sequences (6% belonged to other micro-eukaryotes in the gut, including Entamoeba hartmanni and Blastocystis sp; and only 15 clones/977 (1.5% were related to human 18S rRNA sequences. CONCLUSION: Our results revealed a complex eukaryotic community in the volunteer's gut, with fungi being the most abundant species in the stool sample. Larger investigations are needed to assess the generality of these results and to understand their roles in human health and disease.

  16. Genomic minimalism in the early diverging intestinal parasite Giardia lamblia.

    Science.gov (United States)

    Morrison, Hilary G; McArthur, Andrew G; Gillin, Frances D; Aley, Stephen B; Adam, Rodney D; Olsen, Gary J; Best, Aaron A; Cande, W Zacheus; Chen, Feng; Cipriano, Michael J; Davids, Barbara J; Dawson, Scott C; Elmendorf, Heidi G; Hehl, Adrian B; Holder, Michael E; Huse, Susan M; Kim, Ulandt U; Lasek-Nesselquist, Erica; Manning, Gerard; Nigam, Anuranjini; Nixon, Julie E J; Palm, Daniel; Passamaneck, Nora E; Prabhu, Anjali; Reich, Claudia I; Reiner, David S; Samuelson, John; Svard, Staffan G; Sogin, Mitchell L

    2007-09-28

    The genome of the eukaryotic protist Giardia lamblia, an important human intestinal parasite, is compact in structure and content, contains few introns or mitochondrial relics, and has simplified machinery for DNA replication, transcription, RNA processing, and most metabolic pathways. Protein kinases comprise the single largest protein class and reflect Giardia's requirement for a complex signal transduction network for coordinating differentiation. Lateral gene transfer from bacterial and archaeal donors has shaped Giardia's genome, and previously unknown gene families, for example, cysteine-rich structural proteins, have been discovered. Unexpectedly, the genome shows little evidence of heterozygosity, supporting recent speculations that this organism is sexual. This genome sequence will not only be valuable for investigating the evolution of eukaryotes, but will also be applied to the search for new therapeutics for this parasite.

  17. Women and Parasitic Diseases

    Science.gov (United States)

    ... Consultations, and General Public. Contact Us Parasites Home Women Recommend on Facebook Tweet Share Compartir Infection with ... of parasites can lead to unique consequences for women. Some examples are given below. Infection with Toxoplasma ...

  18. Immunity to parasitic infection

    National Research Council Canada - National Science Library

    Lamb, Tracey J

    2012-01-01

    ... may be manipulated to develop therapeutic interventions against parasitic infection. For easy reference, the most commonly studied parasites are examined in individual chapters written by investigators at the forefront of their field...

  19. Immunity to parasitic infection

    National Research Council Canada - National Science Library

    Lamb, Tracey J

    2012-01-01

    .... Often endemic in developing countries many parasitic diseases are neglected in terms of research funding and much remains to be understood about parasites and the interactions they have with the immune system...

  20. Pets and Parasites

    Science.gov (United States)

    ... good news is that this rarely happens. Most pet-to-people diseases can be avoided by following a few ... your doctor Can a parasite cause death in people and pets? Can human disease from a parasite be treated ...

  1. Symbiosis and the origin of eukaryotic motility

    Science.gov (United States)

    Margulis, L.; Hinkle, G.

    1991-01-01

    Ongoing work to test the hypothesis of the origin of eukaryotic cell organelles by microbial symbioses is discussed. Because of the widespread acceptance of the serial endosymbiotic theory (SET) of the origin of plastids and mitochondria, the idea of the symbiotic origin of the centrioles and axonemes for spirochete bacteria motility symbiosis was tested. Intracellular microtubular systems are purported to derive from symbiotic associations between ancestral eukaryotic cells and motile bacteria. Four lines of approach to this problem are being pursued: (1) cloning the gene of a tubulin-like protein discovered in Spirocheata bajacaliforniesis; (2) seeking axoneme proteins in spirochets by antibody cross-reaction; (3) attempting to cultivate larger, free-living spirochetes; and (4) studying in detail spirochetes (e.g., Cristispira) symbiotic with marine animals. Other aspects of the investigation are presented.

  2. Parasites as prey

    NARCIS (Netherlands)

    Goedknegt, M.A.; Welsh, J.E.; Thieltges, D.W.

    2012-01-01

    Parasites are usually considered to use their hosts as a resource for energy. However, there is increasing awareness that parasites can also become a resource themselves and serve as prey for other organisms. Here we describe various types of predation in which parasites act as prey for other

  3. Neglected Parasitic Infections: Toxocariasis

    Centers for Disease Control (CDC) Podcasts

    This podcast is an overview of the Clinician Outreach and Communication Activity (COCA) Call: Neglected Parasitic Infections in the United States. Neglected Parasitic Infections are a group of diseases that afflict vulnerable populations and are often not well studied or diagnosed. A subject matter expert from CDC's Division of Parasitic Diseases and Malaria describes the epidemiology, diagnosis, and treatment of toxocariasis.

  4. Enzymes from Higher Eukaryotes for Industrial Biocatalysis

    Directory of Open Access Journals (Sweden)

    Zhibin Liu

    2004-01-01

    Full Text Available The industrial production of fine chemicals, feed and food ingredients, pharmaceuticals, agrochemicals and their respective intermediates relies on an increasing application of biocatalysis, i.e. on enzyme or whole-cell catalyzed conversions of molecules. Simple procedures for discovery, cloning and over-expression as well as fast growth favour fungi, yeasts and especially bacteria as sources of biocatalysts. Higher eukaryotes also harbour an almost unlimited number of potential biocatalysts, although to date the limited supply of enzymes, the high heterogeneity of enzyme preparations and the hazard of infectious contaminants keep some interesting candidates out of reach for industrial bioprocesses. In the past only a few animal and plant enzymes from agricultural waste materials were employed in food processing. The use of bacterial expression strains or non-conventional yeasts for the heterologous production of efficient eukaryotic enzymes can overcome the bottleneck in enzyme supply and provide sufficient amounts of homogenous enzyme preparations for reliable and economically feasible applications at large scale. Ideal enzymatic processes represent an environmentally friendly, »near-to-completion« conversion of (mostly non-natural substrates to pure products. Recent developments demonstrate the commercial feasibility of large-scale biocatalytic processes employing enzymes from higher eukaryotes (e.g. plants, animals and also their usefulness in some small-scale industrial applications.

  5. Emerging Functions of Transcription Factors in Malaria Parasite

    Directory of Open Access Journals (Sweden)

    Renu Tuteja

    2011-01-01

    Full Text Available Transcription is a process by which the genetic information stored in DNA is converted into mRNA by enzymes known as RNA polymerase. Bacteria use only one RNA polymerase to transcribe all of its genes while eukaryotes contain three RNA polymerases to transcribe the variety of eukaryotic genes. RNA polymerase also requires other factors/proteins to produce the transcript. These factors generally termed as transcription factors (TFs are either associated directly with RNA polymerase or add in building the actual transcription apparatus. TFs are the most common tools that our cells use to control gene expression. Plasmodium falciparum is responsible for causing the most lethal form of malaria in humans. It shows most of its characteristics common to eukaryotic transcription but it is assumed that mechanisms of transcriptional control in P. falciparum somehow differ from those of other eukaryotes. In this article we describe the studies on the main TFs such as myb protein, high mobility group protein and ApiA2 family proteins from malaria parasite. These studies show that these TFs are slowly emerging to have defined roles in the regulation of gene expression in the parasite.

  6. Comparative analysis of the 5S rRNA and its associated proteins reveals unique primitive rather than parasitic features in Giardia lamblia.

    Science.gov (United States)

    Feng, Jin-Mei; Sun, Jun; Xin, De-Dong; Wen, Jian-Fan

    2012-01-01

    5S rRNA is a highly conserved ribosomal component. Eukaryotic 5S rRNA and its associated proteins (5S rRNA system) have become very well understood. Giardia lamblia was thought by some researchers to be the most primitive extant eukaryote while others considered it a highly evolved parasite. Previous reports have indicated that some aspects of its 5S rRNA system are simpler than that of common eukaryotes. We here explore whether this is true to its entire system, and whether this simplicity is a primitive or parasitic feature. By collecting and confirming pre-existing data and identifying new data, we obtained almost complete datasets of the system of three isolates of G. lamblia, two other parasitic excavates (Trichomonas vaginalis, Trypanosoma cruzi), and one free-living one (Naegleria gruberi). After comprehensively comparing each aspect of the system among these excavates and also with those of archaea and common eukaryotes, we found all the three Giardia isolates to harbor a same simplified 5S rRNA system, which is not only much simpler than that of common eukaryotes but also the simplest one among those of these excavates, and is surprisingly very similar to that of archaea; we also found among these excavates the system in parasitic species is not necessarily simpler than that in free-living species, conversely, the system of free-living species is even simpler in some respects than those of parasitic ones. The simplicity of Giardia 5S rRNA system should be considered a primitive rather than parasitically-degenerated feature. Therefore, Giardia 5S rRNA system might be a primitive system that is intermediate between that of archaea and the common eukaryotic model system, and it may reflect the evolutionary history of the eukaryotic 5S rRNA system from the archaeal form. Our results also imply G. lamblia might be a primitive eukaryote with secondary parasitically-degenerated features.

  7. Acetate formation in the energy metabolism of parasitic helminths and protists.

    Science.gov (United States)

    Tielens, Aloysius G M; van Grinsven, Koen W A; Henze, Katrin; van Hellemond, Jaap J; Martin, William

    2010-03-15

    Formation and excretion of acetate as a metabolic end product of energy metabolism occurs in many protist and helminth parasites, such as the parasitic helminths Fasciola hepatica, Haemonchus contortus and Ascaris suum, and the protist parasites, Giardia lamblia, Entamoeba histolytica, Trichomonas vaginalis as well as Trypanosoma and Leishmania spp. In all of these parasites acetate is a main end product of their energy metabolism, whereas acetate formation does not occur in their mammalian hosts. Acetate production might therefore harbour novel targets for the development of new anti-parasitic drugs. In parasites, acetate is produced from acetyl-CoA by two different reactions, both involving substrate level phosphorylation, that are catalysed by either a cytosolic acetyl-CoA synthetase (ACS) or an organellar acetate:succinate CoA-transferase (ASCT). The ACS reaction is directly coupled to ATP synthesis, whereas the ASCT reaction yields succinyl-CoA for ATP formation via succinyl-CoA synthetase (SCS). Based on recent work on the ASCTs of F. hepatica, T. vaginalis and Trypanosoma brucei we suggest the existence of three subfamilies of enzymes within the CoA-transferase family I. Enzymes of these three subfamilies catalyse the ASCT reaction in eukaryotes via the same mechanism, but the subfamilies share little sequence homology. The CoA-transferases of the three subfamilies are all present inside ATP-producing organelles of parasites, those of subfamily IA in the mitochondria of trypanosomatids, subfamily IB in the mitochondria of parasitic worms and subfamily IC in hydrogenosome-bearing parasites. Together with the recent characterisation among non-parasitic protists of yet a third route of acetate formation involving acetate kinase (ACK) and phosphotransacetylase (PTA) that was previously unknown among eukaryotes, these recent developments provide a good opportunity to have a closer look at eukaryotic acetate formation. (c) 2010 Australian Society for Parasitology

  8. Suppressed Belief

    Directory of Open Access Journals (Sweden)

    Komarine Romdenh-Romluc

    2009-12-01

    Full Text Available Moran’s revised conception of conscious belief requires us to reconceptualise suppressed belief. The work of Merleau-Ponty offers a way to do this. His account of motor-skills allows us to understand suppressed beliefs as pre-reflective ways of dealing with the world.

  9. Paradigms for parasite conservation.

    Science.gov (United States)

    Dougherty, Eric R; Carlson, Colin J; Bueno, Veronica M; Burgio, Kevin R; Cizauskas, Carrie A; Clements, Christopher F; Seidel, Dana P; Harris, Nyeema C

    2016-08-01

    Parasitic species, which depend directly on host species for their survival, represent a major regulatory force in ecosystems and a significant component of Earth's biodiversity. Yet the negative impacts of parasites observed at the host level have motivated a conservation paradigm of eradication, moving us farther from attainment of taxonomically unbiased conservation goals. Despite a growing body of literature highlighting the importance of parasite-inclusive conservation, most parasite species remain understudied, underfunded, and underappreciated. We argue the protection of parasitic biodiversity requires a paradigm shift in the perception and valuation of their role as consumer species, similar to that of apex predators in the mid-20th century. Beyond recognizing parasites as vital trophic regulators, existing tools available to conservation practitioners should explicitly account for the unique threats facing dependent species. We built upon concepts from epidemiology and economics (e.g., host-density threshold and cost-benefit analysis) to devise novel metrics of margin of error and minimum investment for parasite conservation. We define margin of error as the risk of accidental host extinction from misestimating equilibrium population sizes and predicted oscillations, while minimum investment represents the cost associated with conserving the additional hosts required to maintain viable parasite populations. This framework will aid in the identification of readily conserved parasites that present minimal health risks. To establish parasite conservation, we propose an extension of population viability analysis for host-parasite assemblages to assess extinction risk. In the direst cases, ex situ breeding programs for parasites should be evaluated to maximize success without undermining host protection. Though parasitic species pose a considerable conservation challenge, adaptations to conservation tools will help protect parasite biodiversity in the face of

  10. P. berghei telomerase subunit TERT is essential for parasite survival.

    Directory of Open Access Journals (Sweden)

    Agnieszka A Religa

    Full Text Available Telomeres define the ends of chromosomes protecting eukaryotic cells from chromosome instability and eventual cell death. The complex regulation of telomeres involves various proteins including telomerase, which is a specialized ribonucleoprotein responsible for telomere maintenance. Telomeres of chromosomes of malaria parasites are kept at a constant length during blood stage proliferation. The 7-bp telomere repeat sequence is universal across different Plasmodium species (GGGTTT/CA, though the average telomere length varies. The catalytic subunit of telomerase, telomerase reverse transcriptase (TERT, is present in all sequenced Plasmodium species and is approximately three times larger than other eukaryotic TERTs. The Plasmodium RNA component of TERT has recently been identified in silico. A strategy to delete the gene encoding TERT via double cross-over (DXO homologous recombination was undertaken to study the telomerase function in P. berghei. Expression of both TERT and the RNA component (TR in P. berghei blood stages was analysed by Western blotting and Northern analysis. Average telomere length was measured in several Plasmodium species using Telomere Restriction Fragment (TRF analysis. TERT and TR were detected in blood stages and an average telomere length of ∼ 950 bp established. Deletion of the tert gene was performed using standard transfection methodologies and we show the presence of tert- mutants in the transfected parasite populations. Cloning of tert- mutants has been attempted multiple times without success. Thorough analysis of the transfected parasite populations and the parasite obtained from extensive parasite cloning from these populations provide evidence for a so called delayed death phenotype as observed in different organisms lacking TERT. The findings indicate that TERT is essential for P. berghei cell survival. The study extends our current knowledge on telomere biology in malaria parasites and validates further

  11. Phylogenomic analyses support the monophyly of Excavata and resolve relationships among eukaryotic "supergroups".

    Science.gov (United States)

    Hampl, Vladimir; Hug, Laura; Leigh, Jessica W; Dacks, Joel B; Lang, B Franz; Simpson, Alastair G B; Roger, Andrew J

    2009-03-10

    Nearly all of eukaryotic diversity has been classified into 6 suprakingdom-level groups (supergroups) based on molecular and morphological/cell-biological evidence; these are Opisthokonta, Amoebozoa, Archaeplastida, Rhizaria, Chromalveolata, and Excavata. However, molecular phylogeny has not provided clear evidence that either Chromalveolata or Excavata is monophyletic, nor has it resolved the relationships among the supergroups. To establish the affinities of Excavata, which contains parasites of global importance and organisms regarded previously as primitive eukaryotes, we conducted a phylogenomic analysis of a dataset of 143 proteins and 48 taxa, including 19 excavates. Previous phylogenomic studies have not included all major subgroups of Excavata, and thus have not definitively addressed their interrelationships. The enigmatic flagellate Andalucia is sister to typical jakobids. Jakobids (including Andalucia), Euglenozoa and Heterolobosea form a major clade that we name Discoba. Analyses of the complete dataset group Discoba with the mitochondrion-lacking excavates or "metamonads" (diplomonads, parabasalids, and Preaxostyla), but not with the final excavate group, Malawimonas. This separation likely results from a long-branch attraction artifact. Gradual removal of rapidly-evolving taxa from the dataset leads to moderate bootstrap support (69%) for the monophyly of all Excavata, and 90% support once all metamonads are removed. Most importantly, Excavata robustly emerges between unikonts (Amoebozoa + Opisthokonta) and "megagrouping" of Archaeplastida, Rhizaria, and chromalveolates. Our analyses indicate that Excavata forms a monophyletic suprakingdom-level group that is one of the 3 primary divisions within eukaryotes, along with unikonts and a megagroup of Archaeplastida, Rhizaria, and the chromalveolate lineages.

  12. Phylogenetic analysis of ferlin genes reveals ancient eukaryotic origins

    Directory of Open Access Journals (Sweden)

    Lek Monkol

    2010-07-01

    reproduction-related divergence and specialization of species-specific functions within their genus. Conclusions Our phylogenetic studies provide evolutionary insight into the ferlin gene family. We highlight the existence of ferlin-like proteins throughout eukaryotic evolution, from unicellular phytoplankton and apicomplexan parasites, through to humans. We characterise the preservation of ferlin structural motifs, not only of C2 domains, but also the more poorly characterised ferlin-specific motifs representing the DysF, FerA and FerB domains. Our data suggest an ancient role of ferlin proteins, with lessons from vertebrate biology and human disease suggesting a role relating to vesicle fusion and plasma membrane specialization.

  13. Do the mitochondria of malaria parasites behave like the phoenix after return in the mosquito? Regeneration of degenerated mitochondria is required for successful Plasmodium infection.

    NARCIS (Netherlands)

    Bongaerts, G.P.A.

    2005-01-01

    Mitochondria are energy generators in eukaryotic organisms like man and the pathogenic malaria parasites, the Plasmodium spp. From the moment a mosquito-mediated malaria infection occurs in man the parasite multiplies profusely, but eventually the oxygen supply becomes the limiting factor in this

  14. Are Human Intestinal Eukaryotes Beneficial or Commensals?

    Czech Academy of Sciences Publication Activity Database

    Lukeš, Julius; Stensvold, C.R.; Jirků-Pomajbíková, Kateřina; Parfrey, L.W.

    2015-01-01

    Roč. 11, č. 8 (2015), e1005039 E-ISSN 1553-7374 R&D Projects: GA ČR GAP305/12/2261 EU Projects: European Commission(XE) 316304 Institutional support: RVO:60077344 Keywords : human gut microbiota * Blastocystis * infection * diversity * parasites * impact Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 7.003, year: 2015

  15. Prokaryotes versus Eukaryotes: Who is hosting whom?

    Directory of Open Access Journals (Sweden)

    Guillermo eTellez

    2014-10-01

    Full Text Available Microorganisms represent the largest component of biodiversity in our world. For millions of years, prokaryotic microorganisms have functioned as a major selective force shaping eukaryotic evolution. Microbes that live inside and on animals outnumber the animals’ actual somatic and germ cells by an estimated 10-fold. Collectively, the intestinal microbiome represents a ‘forgotten organ’, functioning as an organ inside another that can execute many physiological responsibilities. The nature of primitive eukaryotes was drastically changed due to the association with symbiotic prokaryotes facilitating mutual coevolution of host and microbe. Phytophagous insects have long been used to test theories of evolutionary diversification; moreover, the diversification of a number of phytophagous insect lineages has been linked to mutualisms with microbes. From termites and honey bees to ruminants and mammals, depending on novel biochemistries provided by the prokaryotic microbiome, the association helps to metabolize several nutrients that the host cannot digest and converting these into useful end products (such as short chain fatty acids, a process which has huge impact on the biology and homeostasis of metazoans. More importantly, in a direct and/or indirect way, the intestinal microbiota influences the assembly of gut-associated lymphoid tissue, helps to educate immune system, affects the integrity of the intestinal mucosal barrier, modulates proliferation and differentiation of its epithelial lineages, regulates angiogenesis, and modifies the activity of enteric as well as the central nervous system,. Despite these important effects, the mechanisms by which the gut microbial community influences the host’s biology remains almost entirely unknown. Our aim here is to encourage empirical inquiry into the relationship between mutualism and evolutionary diversification between prokaryotes and eukaryotes which encourage us to postulate: Who is

  16. The Intestinal Eukaryotic and Bacterial Biome of Spotted Hyenas: The Impact of Social Status and Age on Diversity and Composition.

    Science.gov (United States)

    Heitlinger, Emanuel; Ferreira, Susana C M; Thierer, Dagmar; Hofer, Heribert; East, Marion L

    2017-01-01

    In mammals, two factors likely to affect the diversity and composition of intestinal bacteria (bacterial microbiome) and eukaryotes (eukaryome) are social status and age. In species in which social status determines access to resources, socially dominant animals maintain better immune processes and health status than subordinates. As high species diversity is an index of ecosystem health, the intestinal biome of healthier, socially dominant animals should be more diverse than those of subordinates. Gradual colonization of the juvenile intestine after birth predicts lower intestinal biome diversity in juveniles than adults. We tested these predictions on the effect of: (1) age (juvenile/adult) and (2) social status (low/high) on bacterial microbiome and eukaryome diversity and composition in the spotted hyena ( Crocuta crocuta ), a highly social, female-dominated carnivore in which social status determines access to resources. We comprehensively screened feces from 35 individually known adult females and 7 juveniles in the Serengeti ecosystem for bacteria and eukaryotes, using a set of 48 different amplicons (4 for bacterial 16S, 44 for eukaryote 18S) in a multi-amplicon sequencing approach. We compared sequence abundances to classical coprological egg or oocyst counts. For all parasite taxa detected in more than six samples, the number of sequence reads significantly predicted the number of eggs or oocysts counted, underscoring the value of an amplicon sequencing approach for quantitative measurements of parasite load. In line with our predictions, our results revealed a significantly less diverse microbiome in juveniles than adults and a significantly higher diversity of eukaryotes in high-ranking than low-ranking animals. We propose that free-ranging wildlife can provide an intriguing model system to assess the adaptive value of intestinal biome diversity for both bacteria and eukaryotes.

  17. Long- and short-term selective forces on malaria parasite genomes

    DEFF Research Database (Denmark)

    Nygaard, Sanne; Braunstein, Alexander; Malsen, Gareth

    2010-01-01

    Plasmodium parasites, the causal agents of malaria, result in more than 1 million deaths annually. Plasmodium are unicellular eukaryotes with small ~23 Mb genomes encoding ~5200 protein-coding genes. The protein-coding genes comprise about half of these genomes. Although evolutionary processes ha...

  18. Graph theoretic analysis of protein interaction networks of eukaryotes

    Science.gov (United States)

    Goh, K.-I.; Kahng, B.; Kim, D.

    2005-11-01

    Owing to the recent progress in high-throughput experimental techniques, the datasets of large-scale protein interactions of prototypical multicellular species, the nematode worm Caenorhabditis elegans and the fruit fly Drosophila melanogaster, have been assayed. The datasets are obtained mainly by using the yeast hybrid method, which contains false-positive and false-negative simultaneously. Accordingly, while it is desirable to test such datasets through further wet experiments, here we invoke recent developed network theory to test such high-throughput datasets in a simple way. Based on the fact that the key biological processes indispensable to maintaining life are conserved across eukaryotic species, and the comparison of structural properties of the protein interaction networks (PINs) of the two species with those of the yeast PIN, we find that while the worm and yeast PIN datasets exhibit similar structural properties, the current fly dataset, though most comprehensively screened ever, does not reflect generic structural properties correctly as it is. The modularity is suppressed and the connectivity correlation is lacking. Addition of interologs to the current fly dataset increases the modularity and enhances the occurrence of triangular motifs as well. The connectivity correlation function of the fly, however, remains distinct under such interolog additions, for which we present a possible scenario through an in silico modeling.

  19. Consistent mutational paths predict eukaryotic thermostability

    Directory of Open Access Journals (Sweden)

    van Noort Vera

    2013-01-01

    Full Text Available Abstract Background Proteomes of thermophilic prokaryotes have been instrumental in structural biology and successfully exploited in biotechnology, however many proteins required for eukaryotic cell function are absent from bacteria or archaea. With Chaetomium thermophilum, Thielavia terrestris and Thielavia heterothallica three genome sequences of thermophilic eukaryotes have been published. Results Studying the genomes and proteomes of these thermophilic fungi, we found common strategies of thermal adaptation across the different kingdoms of Life, including amino acid biases and a reduced genome size. A phylogenetics-guided comparison of thermophilic proteomes with those of other, mesophilic Sordariomycetes revealed consistent amino acid substitutions associated to thermophily that were also present in an independent lineage of thermophilic fungi. The most consistent pattern is the substitution of lysine by arginine, which we could find in almost all lineages but has not been extensively used in protein stability engineering. By exploiting mutational paths towards the thermophiles, we could predict particular amino acid residues in individual proteins that contribute to thermostability and validated some of them experimentally. By determining the three-dimensional structure of an exemplar protein from C. thermophilum (Arx1, we could also characterise the molecular consequences of some of these mutations. Conclusions The comparative analysis of these three genomes not only enhances our understanding of the evolution of thermophily, but also provides new ways to engineer protein stability.

  20. Strong eukaryotic IRESs have weak secondary structure.

    Directory of Open Access Journals (Sweden)

    Xuhua Xia

    Full Text Available BACKGROUND: The objective of this work was to investigate the hypothesis that eukaryotic Internal Ribosome Entry Sites (IRES lack secondary structure and to examine the generality of the hypothesis. METHODOLOGY/PRINCIPAL FINDINGS: IRESs of the yeast and the fruit fly are located in the 5'UTR immediately upstream of the initiation codon. The minimum folding energy (MFE of 60 nt RNA segments immediately upstream of the initiation codons was calculated as a proxy of secondary structure stability. MFE of the reverse complements of these 60 nt segments was also calculated. The relationship between MFE and empirically determined IRES activity was investigated to test the hypothesis that strong IRES activity is associated with weak secondary structure. We show that IRES activity in the yeast and the fruit fly correlates strongly with the structural stability, with highest IRES activity found in RNA segments that exhibit the weakest secondary structure. CONCLUSIONS: We found that a subset of eukaryotic IRESs exhibits very low secondary structure in the 5'-UTR sequences immediately upstream of the initiation codon. The consistency in results between the yeast and the fruit fly suggests a possible shared mechanism of cap-independent translation initiation that relies on an unstructured RNA segment.

  1. RNA Export through the NPC in Eukaryotes.

    Science.gov (United States)

    Okamura, Masumi; Inose, Haruko; Masuda, Seiji

    2015-03-20

    In eukaryotic cells, RNAs are transcribed in the nucleus and exported to the cytoplasm through the nuclear pore complex. The RNA molecules that are exported from the nucleus into the cytoplasm include messenger RNAs (mRNAs), ribosomal RNAs (rRNAs), transfer RNAs (tRNAs), small nuclear RNAs (snRNAs), micro RNAs (miRNAs), and viral mRNAs. Each RNA is transported by a specific nuclear export receptor. It is believed that most of the mRNAs are exported by Nxf1 (Mex67 in yeast), whereas rRNAs, snRNAs, and a certain subset of mRNAs are exported in a Crm1/Xpo1-dependent manner. tRNAs and miRNAs are exported by Xpot and Xpo5. However, multiple export receptors are involved in the export of some RNAs, such as 60S ribosomal subunit. In addition to these export receptors, some adapter proteins are required to export RNAs. The RNA export system of eukaryotic cells is also used by several types of RNA virus that depend on the machineries of the host cell in the nucleus for replication of their genome, therefore this review describes the RNA export system of two representative viruses. We also discuss the NPC anchoring-dependent mRNA export factors that directly recruit specific genes to the NPC.

  2. Foodborne parasites from wildlife

    DEFF Research Database (Denmark)

    Kapel, Christian Moliin Outzen; Fredensborg, Brian Lund

    2015-01-01

    The majority of wild foods consumed by humans are sourced from intensively managed or semi-farmed populations. Management practices inevitably affect wildlife density and habitat characteristics, which are key elements in the transmission of parasites. We consider the risk of transmission...... of foodborne parasites to humans from wildlife maintained under natural or semi-natural conditions. A deeper understanding will be useful in counteracting foodborne parasites arising from the growing industry of novel and exotic foods....

  3. Parasites, Plants, and People.

    Science.gov (United States)

    Johnson, Marion; Moore, Tony

    2016-06-01

    Anthelminthic resistance is acknowledged worldwide and is a major problem in Aotearoa New Zealand, thus alternative parasite management strategies are imperative. One Health is an initiative linking animal, human, and environmental health. Parasites, plants, and people illustrate the possibilities of providing diverse diets for stock thereby lowering parasite burdens, improving the cultural wellbeing of a local community, and protecting the environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Intestinal parasites and tuberculosis

    Directory of Open Access Journals (Sweden)

    Anuar Alonso Cedeño-Burbano

    2017-10-01

    Conclusions: The available evidence was insufficient to affirm that intestinal parasites predispose to developing tuberculous. The studies carried out so far have found statistically insignificant results.

  5. Neglected Parasitic Infections: Toxocariasis

    Centers for Disease Control (CDC) Podcasts

    2012-01-05

    This podcast is an overview of the Clinician Outreach and Communication Activity (COCA) Call: Neglected Parasitic Infections in the United States. Neglected Parasitic Infections are a group of diseases that afflict vulnerable populations and are often not well studied or diagnosed. A subject matter expert from CDC's Division of Parasitic Diseases and Malaria describes the epidemiology, diagnosis, and treatment of toxocariasis.  Created: 1/5/2012 by Center for Global Health, Division of Parasitic Diseases and Malaria (DPDM); Emergency Risk Communication Branch (ERCB)/Joint Information Center (JIC), Office of Public Health Preparedness and Response (OPHPR).   Date Released: 1/9/2012.

  6. Do the mitochondria of malaria parasites behave like the phoenix after return in the mosquito? Regeneration of degenerated mitochondria is required for successful Plasmodium infection.

    Science.gov (United States)

    Bongaerts, Ger

    2005-01-01

    Mitochondria are energy generators in eukaryotic organisms like man and the pathogenic malaria parasites, the Plasmodium spp. From the moment a mosquito-mediated malaria infection occurs in man the parasite multiplies profusely, but eventually the oxygen supply becomes the limiting factor in this process. Consequently, the parasite will increasingly generate energy (and lactic acid) from sugar fermentation. Simultaneously, the cristate structure of Plasmodium mitochondria degenerates and becomes acristate. The degenerated acristate mitochondria of mammalian Plasmodium parasites seem to be able to revitalise by transforming to cristate mitochondria inside the oxygen-rich mosquito, like the rebirth of the old phoenix. In this way the infectivity of the parasite is revitalised.

  7. The Genome of Naegleria gruberi Illuminates Early Eukaryotic Versatility

    Energy Technology Data Exchange (ETDEWEB)

    Fritz-Laylin, Lillian K.; Prochnik, Simon E.; Ginger, Michael L.; Dacks, Joel; Carpenter, Meredith L.; Field, Mark C.; Kuo, Alan; Paredez, Alex; Chapman, Jarrod; Pham, Jonathan; Shu, Shengqiang; Neupane, Rochak; Cipriano, Michael; Mancuso, Joel; Tu, Hank; Salamov, Asaf; Lindquist, Erika; Shapiro, Harris; Lucas, Susan; Grigoriev, Igor V.; Cande, W. Zacheus; Fulton, Chandler; Rokhsar, Daniel S.; Dawson, Scott C.

    2010-03-01

    Genome sequences of diverse free-living protists are essential for understanding eukaryotic evolution and molecular and cell biology. The free-living amoeboflagellate Naegleria gruberi belongs to a varied and ubiquitous protist clade (Heterolobosea) that diverged from other eukaryotic lineages over a billion years ago. Analysis of the 15,727 protein-coding genes encoded by Naegleria's 41 Mb nuclear genome indicates a capacity for both aerobic respiration and anaerobic metabolism with concomitant hydrogen production, with fundamental implications for the evolution of organelle metabolism. The Naegleria genome facilitates substantially broader phylogenomic comparisons of free-living eukaryotes than previously possible, allowing us to identify thousands of genes likely present in the pan-eukaryotic ancestor, with 40% likely eukaryotic inventions. Moreover, we construct a comprehensive catalog of amoeboid-motility genes. The Naegleria genome, analyzed in the context of other protists, reveals a remarkably complex ancestral eukaryote with a rich repertoire of cytoskeletal, sexual, signaling, and metabolic modules.

  8. PARASITES OF FISH

    Science.gov (United States)

    The intent of this chapter is to describe the parasites of importance to fishes maintained and used in laboratory settings. In contrast to the frist edition, the focus will be only on those parasites that pose a serious threat to or are common in fishes held in these confined en...

  9. Parasites from the Past

    DEFF Research Database (Denmark)

    Søe, Martin Jensen; Fredensborg, Brian Lund; Nejsum, Peter

    will investigate how the diversity of food-borne parasitic infections has changed with cultural and dietary habits, hunting practice and intensity of animal husbandry. This is done by isolating and typing ancient DNA remains from parasite eggs found in archeological samples from across Denmark....

  10. Ultrastructural diversity between centrioles of eukaryotes.

    Science.gov (United States)

    Gupta, Akshari; Kitagawa, Daiju

    2018-02-16

    Several decades of centriole research have revealed the beautiful symmetry present in these microtubule-based organelles, which are required to form centrosomes, cilia, and flagella in many eukaryotes. Centriole architecture is largely conserved across most organisms, however, individual centriolar features such as the central cartwheel or microtubule walls exhibit considerable variability when examined with finer resolution. Here, we review the ultrastructural characteristics of centrioles in commonly studied organisms, highlighting the subtle and not-so-subtle differences between specific structural components of these centrioles. Additionally, we survey some non-canonical centriole structures that have been discovered in various species, from the coaxial bicentrioles of protists and lower land plants to the giant irregular centrioles of the fungus gnat Sciara. Finally, we speculate on the functional significance of these differences between centrioles, and the contribution of individual structural elements such as the cartwheel or microtubules towards the stability of centrioles.Centriole structure, cartwheel, triplet microtubules, SAS-6, centrosome.

  11. Protein splicing and its evolution in eukaryotes

    Directory of Open Access Journals (Sweden)

    Starokadomskyy P. L.

    2010-02-01

    Full Text Available Inteins, or protein introns, are parts of protein sequences that are post-translationally excised, their flanking regions (exteins being spliced together. This process was called protein splicing. Originally inteins were found in prokaryotic or unicellular eukaryotic organisms. But the general principles of post-translation protein rearrangement are evolving yielding different post-translation modification of proteins in multicellular organisms. For clarity, these non-intein mediated events call either protein rearrangements or protein editing. The most intriguing example of protein editing is proteasome-mediated splicing of antigens in vertebrates that may play important role in antigen presentation. Other examples of protein rearrangements are maturation of Hg-proteins (critical receptors in embryogenesis as well as maturation of several metabolic enzymes. Despite a lack of experimental data we try to analyze some intriguing examples of protein splicing evolution.

  12. Redox characteristics of the eukaryotic cytosol

    DEFF Research Database (Denmark)

    López-Mirabal, H Reynaldo; Winther, Jakob R

    2007-01-01

    The eukaryotic cytoplasm has long been regarded as a cellular compartment in which the reduced state of protein cysteines is largely favored. Under normal conditions, the cytosolic low-molecular weight redox buffer, comprising primarily of glutathione, is highly reducing and reactive oxygen species...... (ROS) and glutathionylated proteins are maintained at very low levels. In the present review, recent progress in the understanding of the cytosolic thiol-disulfide redox metabolism and novel analytical approaches to studying cytosolic redox properties are discussed. We will focus on the yeast model...... organism, Saccharomyces cerevisiae, where the combination of genetic and biochemical approaches has brought us furthest in understanding the mechanisms underlying cellular redox regulation. It has been shown in yeast that, in addition to the enzyme glutathione reductase, other mechanisms may exist...

  13. Bacterial proteins pinpoint a single eukaryotic root

    Czech Academy of Sciences Publication Activity Database

    Derelle, R.; Torruella, G.; Klimeš, V.; Brinkmann, H.; Kim, E.; Vlček, Čestmír; Lang, B.F.; Eliáš, M.

    2015-01-01

    Roč. 112, č. 7 (2015), E693-E699 ISSN 0027-8424 R&D Projects: GA ČR GA13-24983S Grant - others:GA MŠk(CZ) ED2.1.00/03.0100; Howard Hughes Medical Institute International Early Career Scientist Program(US) 55007424; Spanish Ministry of Economy and Competitiveness, European Molecular Biology Organization Young Investigator Program(ES) BFU2012-31329; Spanish Ministry of Economy and Competitiveness, "Centro de Excelencia Severo Ochoa" - European Regional Development Fund(ES) Sev-2012-0208, BES-2013-064004 Institutional support: RVO:68378050 Keywords : eukaryote phylogeny * phylogenomics * Opimoda * Diphoda * LECA Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 9.423, year: 2015

  14. Different polyamine pathways from bacteria have replaced eukaryotic spermidine biosynthesis in ciliates Tetrahymena thermophila and Paramecium tetaurelia.

    Science.gov (United States)

    Li, Bin; Kim, Sok Ho; Zhang, Yang; Hanfrey, Colin C; Elliott, Katherine A; Ealick, Steven E; Michael, Anthony J

    2015-09-01

    The polyamine spermidine is absolutely required for growth and cell proliferation in eukaryotes, due to its role in post-translational modification of essential translation elongation factor eIF5A, mediated by deoxyhypusine synthase. We have found that free-living ciliates Tetrahymena and Paramecium lost the eukaryotic genes encoding spermidine biosynthesis: S-adenosylmethionine decarboxylase (AdoMetDC) and spermidine synthase (SpdSyn). In Tetrahymena, they were replaced by a gene encoding a fusion protein of bacterial AdoMetDC and SpdSyn, present as three copies. In Paramecium, a bacterial homospermidine synthase replaced the eukaryotic genes. Individual AdoMetDC-SpdSyn fusion protein paralogues from Tetrahymena exhibit undetectable AdoMetDC activity; however, when two paralogous fusion proteins are mixed, AdoMetDC activity is restored and spermidine is synthesized. Structural modelling indicates a functional active site is reconstituted by sharing critical residues from two defective protomers across the heteromer interface. Paramecium was found to accumulate homospermidine, suggesting it replaces spermidine for growth. To test this concept, a budding yeast spermidine auxotrophic strain was found to grow almost normally with homospermidine instead of spermidine. Biosynthesis of spermidine analogue aminopropylcadaverine, but not exogenously provided norspermidine, correlated with some growth. Finally, we found that diverse single-celled eukaryotic parasites and multicellular metazoan Schistosoma worms have lost the spermidine biosynthetic pathway but retain deoxyhypusine synthase. © 2015 John Wiley & Sons Ltd.

  15. Host-parasite interactions and ecology of the malaria parasite-a bioinformatics approach.

    Science.gov (United States)

    Izak, Dariusz; Klim, Joanna; Kaczanowski, Szymon

    2018-04-25

    Malaria remains one of the highest mortality infectious diseases. Malaria is caused by parasites from the genus Plasmodium. Most deaths are caused by infections involving Plasmodium falciparum, which has a complex life cycle. Malaria parasites are extremely well adapted for interactions with their host and their host's immune system and are able to suppress the human immune system, erase immunological memory and rapidly alter exposed antigens. Owing to this rapid evolution, parasites develop drug resistance and express novel forms of antigenic proteins that are not recognized by the host immune system. There is an emerging need for novel interventions, including novel drugs and vaccines. Designing novel therapies requires knowledge about host-parasite interactions, which is still limited. However, significant progress has recently been achieved in this field through the application of bioinformatics analysis of parasite genome sequences. In this review, we describe the main achievements in 'malarial' bioinformatics and provide examples of successful applications of protein sequence analysis. These examples include the prediction of protein functions based on homology and the prediction of protein surface localization via domain and motif analysis. Additionally, we describe PlasmoDB, a database that stores accumulated experimental data. This tool allows data mining of the stored information and will play an important role in the development of malaria science. Finally, we illustrate the application of bioinformatics in the development of population genetics research on malaria parasites, an approach referred to as reverse ecology.

  16. Inevitability of Genetic Parasites

    Science.gov (United States)

    Iranzo, Jaime; Puigbò, Pere; Lobkovsky, Alexander E.; Wolf, Yuri I.

    2016-01-01

    Abstract Almost all cellular life forms are hosts to diverse genetic parasites with various levels of autonomy including plasmids, transposons and viruses. Theoretical modeling of the evolution of primordial replicators indicates that parasites (cheaters) necessarily evolve in such systems and can be kept at bay primarily via compartmentalization. Given the (near) ubiquity, abundance and diversity of genetic parasites, the question becomes pertinent: are such parasites intrinsic to life? At least in prokaryotes, the persistence of parasites is linked to the rate of horizontal gene transfer (HGT). We mathematically derive the threshold value of the minimal transfer rate required for selfish element persistence, depending on the element duplication and loss rates as well as the cost to the host. Estimation of the characteristic gene duplication, loss and transfer rates for transposons, plasmids and virus-related elements in multiple groups of diverse bacteria and archaea indicates that most of these rates are compatible with the long term persistence of parasites. Notably, a small but non-zero rate of HGT is also required for the persistence of non-parasitic genes. We hypothesize that cells cannot tune their horizontal transfer rates to be below the threshold required for parasite persistence without experiencing highly detrimental side-effects. As a lower boundary to the minimum DNA transfer rate that a cell can withstand, we consider the process of genome degradation and mutational meltdown of populations through Muller’s ratchet. A numerical assessment of this hypothesis suggests that microbial populations cannot purge parasites while escaping Muller’s ratchet. Thus, genetic parasites appear to be virtually inevitable in cellular organisms. PMID:27503291

  17. Interocular suppression

    Science.gov (United States)

    Tuna, Ana Rita; Almeida Neves Carrega, Filipa; Nunes, Amélia Fernandes

    2017-08-01

    The objective of this work is to quantify the suppressive imbalance, based on the manipulation of ocular luminance, between a group of subjects with normal binocular vision and a group of subjects with amblyopia. The result reveals that there are statistically significant differences in interocular dominance between two groups, evidencing a greater suppressive imbalance in amblyopic subjects. The technique used, proved to be a simple, easy to apply and economic method, for quantified ocular dominance. It is presented as a technique with the potential to accompany subjects with a marked dominance in one of the eyes that makes fusion difficult.

  18. DNA to DNA transcription might exist in eukaryotic cells

    OpenAIRE

    Li, Gao-De

    2016-01-01

    Till now, in biological sciences, the term, transcription, mainly refers to DNA to RNA transcription. But our recently published experimental findings obtained from Plasmodium falciparum strongly suggest the existence of DNA to DNA transcription in the genome of eukaryotic cells, which could shed some light on the functions of certain noncoding DNA in the human and other eukaryotic genomes.

  19. Morphological and ecological complexity in early eukaryotic ecosystems.

    Science.gov (United States)

    Javaux, E J; Knoll, A H; Walter, M R

    2001-07-05

    Molecular phylogeny and biogeochemistry indicate that eukaryotes differentiated early in Earth history. Sequence comparisons of small-subunit ribosomal RNA genes suggest a deep evolutionary divergence of Eukarya and Archaea; C27-C29 steranes (derived from sterols synthesized by eukaryotes) and strong depletion of 13C (a biogeochemical signature of methanogenic Archaea) in 2,700 Myr old kerogens independently place a minimum age on this split. Steranes, large spheroidal microfossils, and rare macrofossils of possible eukaryotic origin occur in Palaeoproterozoic rocks. Until now, however, evidence for morphological and taxonomic diversification within the domain has generally been restricted to very late Mesoproterozoic and Neoproterozoic successions. Here we show that the cytoskeletal and ecological prerequisites for eukaryotic diversification were already established in eukaryotic microorganisms fossilized nearly 1,500 Myr ago in shales of the early Mesoproterozoic Roper Group in northern Australia.

  20. Positive selection for unpreferred codon usage in eukaryotic genomes

    Directory of Open Access Journals (Sweden)

    Galagan James E

    2007-07-01

    Full Text Available Abstract Background Natural selection has traditionally been understood as a force responsible for pushing genes to states of higher translational efficiency, whereas lower translational efficiency has been explained by neutral mutation and genetic drift. We looked for evidence of directional selection resulting in increased unpreferred codon usage (and presumably reduced translational efficiency in three divergent clusters of eukaryotic genomes using a simple optimal-codon-based metric (Kp/Ku. Results Here we show that for some genes natural selection is indeed responsible for causing accelerated unpreferred codon substitution, and document the scope of this selection. In Cryptococcus and to a lesser extent Drosophila, we find many genes showing a statistically significant signal of selection for unpreferred codon usage in one or more lineages. We did not find evidence for this type of selection in Saccharomyces. The signal of positive selection observed from unpreferred synonymous codon substitutions is coincident in Cryptococcus and Drosophila with the distribution of upstream open reading frames (uORFs, another genic feature known to reduce translational efficiency. Functional enrichment analysis of genes exhibiting low Kp/Ku ratios reveals that genes in regulatory roles are particularly subject to this type of selection. Conclusion Through genome-wide scans, we find recent selection for unpreferred codon usage at approximately 1% of genetic loci in a Cryptococcus and several genes in Drosophila. Unpreferred codons can impede translation efficiency, and we find that genes with translation-impeding uORFs are enriched for this selection signal. We find that regulatory genes are particularly likely to be subject to selection for unpreferred codon usage. Given that expression noise can propagate through regulatory cascades, and that low translational efficiency can reduce expression noise, this finding supports the hypothesis that translational

  1. Natural metabolites for parasitic weed management.

    Science.gov (United States)

    Vurro, Maurizio; Boari, Angela; Evidente, Antonio; Andolfi, Anna; Zermane, Nadjia

    2009-05-01

    Compounds of natural origin, such as phytotoxins produced by fungi or natural amino acids, could be used in parasitic weed management strategies by interfering with the early growth stages of the parasites. These metabolites could inhibit seed germination or germ tube elongation, so preventing attachment to the host plant, or, conversely, stimulate seed germination in the absence of the host, contributing to a reduction in the parasite seed bank. Some of the fungal metabolites assayed were very active even at very low concentrations, such as some macrocyclic trichothecenes, which at 0.1 microM strongly suppressed the germination of Orobanche ramosa L. seeds. Interesting results were also obtained with some novel toxins, such as phyllostictine A, highly active in reducing germ tube elongation and seed germination both of O. ramosa and of Cuscuta campestris Yuncker. Among the amino acids tested, methionine and arginine were particularly interesting, as they were able to suppress seed germination at concentrations lower than 1 mM. Some of the fungal metabolites tested were also able to stimulate the germination of O. ramosa seeds. The major findings in this research field are described and discussed.

  2. Genomic impact of eukaryotic transposable elements.

    Science.gov (United States)

    Arkhipova, Irina R; Batzer, Mark A; Brosius, Juergen; Feschotte, Cédric; Moran, John V; Schmitz, Jürgen; Jurka, Jerzy

    2012-11-21

    The third international conference on the genomic impact of eukaryotic transposable elements (TEs) was held 24 to 28 February 2012 at the Asilomar Conference Center, Pacific Grove, CA, USA. Sponsored in part by the National Institutes of Health grant 5 P41 LM006252, the goal of the conference was to bring together researchers from around the world who study the impact and mechanisms of TEs using multiple computational and experimental approaches. The meeting drew close to 170 attendees and included invited floor presentations on the biology of TEs and their genomic impact, as well as numerous talks contributed by young scientists. The workshop talks were devoted to computational analysis of TEs with additional time for discussion of unresolved issues. Also, there was ample opportunity for poster presentations and informal evening discussions. The success of the meeting reflects the important role of Repbase in comparative genomic studies, and emphasizes the need for close interactions between experimental and computational biologists in the years to come.

  3. Genomic impact of eukaryotic transposable elements

    Directory of Open Access Journals (Sweden)

    Arkhipova Irina R

    2012-11-01

    Full Text Available Abstract The third international conference on the genomic impact of eukaryotic transposable elements (TEs was held 24 to 28 February 2012 at the Asilomar Conference Center, Pacific Grove, CA, USA. Sponsored in part by the National Institutes of Health grant 5 P41 LM006252, the goal of the conference was to bring together researchers from around the world who study the impact and mechanisms of TEs using multiple computational and experimental approaches. The meeting drew close to 170 attendees and included invited floor presentations on the biology of TEs and their genomic impact, as well as numerous talks contributed by young scientists. The workshop talks were devoted to computational analysis of TEs with additional time for discussion of unresolved issues. Also, there was ample opportunity for poster presentations and informal evening discussions. The success of the meeting reflects the important role of Repbase in comparative genomic studies, and emphasizes the need for close interactions between experimental and computational biologists in the years to come.

  4. Do lipids shape the eukaryotic cell cycle?

    Science.gov (United States)

    Furse, Samuel; Shearman, Gemma C

    2018-01-01

    Successful passage through the cell cycle presents a number of structural challenges to the cell. Inceptive studies carried out in the last five years have produced clear evidence of modulations in the lipid profile (sometimes referred to as the lipidome) of eukaryotes as a function of the cell cycle. This mounting body of evidence indicates that lipids play key roles in the structural transformations seen across the cycle. The accumulation of this evidence coincides with a revolution in our understanding of how lipid composition regulates a plethora of biological processes ranging from protein activity through to cellular signalling and membrane compartmentalisation. In this review, we discuss evidence from biological, chemical and physical studies of the lipid fraction across the cell cycle that demonstrate that lipids are well-developed cellular components at the heart of the biological machinery responsible for managing progress through the cell cycle. Furthermore, we discuss the mechanisms by which this careful control is exercised. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

  5. Children and Parasitic Diseases

    Science.gov (United States)

    ... because they disproportionately affect impoverished people. More on: Neglected Tropical Diseases Prevention One of the most important ways to help prevent these parasitic diseases is to teach children the importance of washing hands correctly with soap ...

  6. Parasites and the skin

    African Journals Online (AJOL)

    2009-06-11

    Jun 11, 2009 ... those conditions that are encountered in daily practice and to remind you of those ... care conditions. Parasitic infections can be solely confined to the skin, as seen ..... endemic areas or may become chronic and disseminate.

  7. Parasitic Diseases: Glossary

    Science.gov (United States)

    ... of the leg. Endemic: A disease that is native to a particular geographic region. Epidemiology: The study ... parasites/glossary.html) T Telediagnosis: The transmission of digital images captured from a clinical specimen and sent ...

  8. The role of extracellular vesicles in parasite-host interaction

    Directory of Open Access Journals (Sweden)

    Justyna Gatkowska

    2016-09-01

    Full Text Available Extracellular vesicles (EVs, initially considered cell debris, were soon proved to be an essential tool of intercellular communication enabling the exchange of information without direct contact of the cells. At present EVs are the subject of extensive research due to their universal presence in single- and multi-cell organisms, regardless of their systematic position, and their substantial role in cell-to-cell communication. EVs seem to be released by both prokaryotic and eukaryotic cells under natural (in vivo and laboratory (in vitro conditions. Even purified fractions of isolated EVs comprise various membrane-derived structures. However, EVs can be classified into general groups based primarily on their size and origin. EVs may carry various materials, and ongoing research investigations give new insight into their potenti participation in critical biological processes, e.g. carcinogenesis. This paper presents current knowledge on the EVs’ involvement in host–parasite interactions including the invasion process, the maintenance of the parasite infection and modulation of the host immune response to parasite antigenic stimulation, as well as perspectives of the potential use of EVs as immunoprophylactic and diagnostic tools for controlling parasite infections. The most numerous literature data concern protozoan parasites, especially those of the greatest medical and social importance worldwide. However, available information about the EVs’ contribution to helminth invasion has also been included.

  9. Imaging of parasitic diseases

    International Nuclear Information System (INIS)

    Haddad, Maurice C.

    2008-01-01

    This book provides an overview of the imaging findings of parasitic diseases using modern imaging equipment. The chapters consist of short descriptions of causative pathogens, epidemiology, modes of transmission, pathology, clinical manifestations, laboratory tests, and imaging findings, with illustrative examples of parasitic diseases that can affect various systems of the human body. Tables summarizing key diagnostic features and clinical data pertinent to diagnosis are also included. This book is intended for radiologists worldwide. (orig.)

  10. Imaging of parasitic diseases

    Energy Technology Data Exchange (ETDEWEB)

    Haddad, Maurice C. [American Univ. of Beirut Medical Center (Lebanon). Dept. of Diagnostic Radiology; Abd El Bagi, Mohamed E. [Riyadh Military Hospital (Saudi Arabia). Radiology and Imaging Dept. 920W; Tamraz, Jean C. (eds.) [CHU Hotel-Dieu de France, Beirut (Lebanon)

    2008-07-01

    This book provides an overview of the imaging findings of parasitic diseases using modern imaging equipment. The chapters consist of short descriptions of causative pathogens, epidemiology, modes of transmission, pathology, clinical manifestations, laboratory tests, and imaging findings, with illustrative examples of parasitic diseases that can affect various systems of the human body. Tables summarizing key diagnostic features and clinical data pertinent to diagnosis are also included. This book is intended for radiologists worldwide. (orig.)

  11. Pathoecology of Chiribaya parasitism

    Directory of Open Access Journals (Sweden)

    Martinson Elizabeth

    2003-01-01

    Full Text Available The excavations of Chiribaya culture sites in the Osmore drainage of southern Peru focused on the recovery of information about prehistoric disease, including parasitism. The archaeologists excavated human, dog, guinea pig, and llama mummies. These mummies were analyzed for internal and external parasites. The results of the analysis and reconstruction of prehistoric life from the excavations allows us to interpret the pathoecology of the Chiribaya culture.

  12. Prevalence of Parasitic Contamination

    Science.gov (United States)

    Ismail, Yazan

    2016-01-01

    One of the main ways in transmitting parasites to humans is through consuming contaminated raw vegetables. The aim of this study was to evaluate the prevalence of parasitological contamination (helminthes eggs, Giardia and Entamoeba histolytica cysts) of salad vegetables sold at supermarkets and street vendors in Amman and Baqa’a – Jordan. A total of 133 samples of salad vegetables were collected and examined for the prevalence of parasites. It was found that 29% of the samples were contaminated with different parasites. Of the 30 lettuce, 33 tomato, 42 parsley and 28 cucumber samples examined the prevalence of Ascaris spp. eggs was 43%, 15%, 21% and 4%; Toxocara spp. eggs was 30%, 0%, 0% and 4%; Giardia spp. cysts was 23%, 6%, 0% and 0%; Taenia/Echinococcus eggs was 20%, 0%, 5% and 0%; Fasciola hepatica eggs was 13%, 3%, 2% and 0%; and E. histolytica cysts was 10%, 6%, 0% and 0%, respectively. There was no significant difference in the prevalence of parasite in salad vegetables either between supermarkets and street vendors, or between Amman and Baqa’a, Ascaris spp. was found to be the highest prevalent parasite in salad vegetables from supermarkets and street vendors and from Amman and Baqa’a. Our results pointed out that, the parasitic contamination of salad vegetables found in our study might be caused by irrigating crops with faecal contaminated water. We concluded that salad vegetables sold in Amman and Baqa’a may cause a health risk to consumers.

  13. Parasites in marine food webs

    Science.gov (United States)

    Lafferty, Kevin D.

    2013-01-01

    Most species interactions probably involve parasites. This review considers the extent to which marine ecologists should consider parasites to fully understand marine communities. Parasites are influential parts of food webs in estuaries, temperate reefs, and coral reefs, but their ecological importance is seldom recognized. Though difficult to observe, parasites can have substantial biomass, and they can be just as common as free-living consumers after controlling for body mass and trophic level. Parasites have direct impacts on the energetics of their hosts and some affect host behaviors, with ecosystem-level consequences. Although they cause disease, parasites are sensitive components of ecosystems. In particular, they suffer secondary extinctions due to biodiversity loss. Some parasites can also return to a system after habitat restoration. For these reasons, parasites can make good indicators of ecosystem integrity. Fishing can indirectly increase or decrease parasite populations and the effects of climate change on parasites are likely to be equally as complex.

  14. Structure of the prolyl-tRNA synthetase from the eukaryotic pathogen Giardia lamblia

    Energy Technology Data Exchange (ETDEWEB)

    Larson, Eric T.; Kim, Jessica E.; Napuli, Alberto J.; Verlinde, Christophe L. M. J.; Fan, Erkang; Zucker, Frank H.; Van Voorhis, Wesley C.; Buckner, Frederick S.; Hol, Wim G. J.; Merritt, Ethan A., E-mail: merritt@u.washington.edu [Medical Structural Genomics of Pathogenic Protozoa, (United States); University of Washington, Seattle, WA 98195 (United States)

    2012-09-01

    The structure of Giardia prolyl-tRNA synthetase cocrystallized with proline and ATP shows evidence for half-of-the-sites activity, leading to a corresponding mixture of reaction substrates and product (prolyl-AMP) in the two active sites of the dimer. The genome of the human intestinal parasite Giardia lamblia contains only a single aminoacyl-tRNA synthetase gene for each amino acid. The Giardia prolyl-tRNA synthetase gene product was originally misidentified as a dual-specificity Pro/Cys enzyme, in part owing to its unexpectedly high off-target activation of cysteine, but is now believed to be a normal representative of the class of archaeal/eukaryotic prolyl-tRNA synthetases. The 2.2 Å resolution crystal structure of the G. lamblia enzyme presented here is thus the first structure determination of a prolyl-tRNA synthetase from a eukaryote. The relative occupancies of substrate (proline) and product (prolyl-AMP) in the active site are consistent with half-of-the-sites reactivity, as is the observed biphasic thermal denaturation curve for the protein in the presence of proline and MgATP. However, no corresponding induced asymmetry is evident in the structure of the protein. No thermal stabilization is observed in the presence of cysteine and ATP. The implied low affinity for the off-target activation product cysteinyl-AMP suggests that translational fidelity in Giardia is aided by the rapid release of misactivated cysteine.

  15. Genome-reconstruction for eukaryotes from complex natural microbial communities.

    Science.gov (United States)

    West, Patrick T; Probst, Alexander J; Grigoriev, Igor V; Thomas, Brian C; Banfield, Jillian F

    2018-04-01

    Microbial eukaryotes are integral components of natural microbial communities, and their inclusion is critical for many ecosystem studies, yet the majority of published metagenome analyses ignore eukaryotes. In order to include eukaryotes in environmental studies, we propose a method to recover eukaryotic genomes from complex metagenomic samples. A key step for genome recovery is separation of eukaryotic and prokaryotic fragments. We developed a k -mer-based strategy, EukRep, for eukaryotic sequence identification and applied it to environmental samples to show that it enables genome recovery, genome completeness evaluation, and prediction of metabolic potential. We used this approach to test the effect of addition of organic carbon on a geyser-associated microbial community and detected a substantial change of the community metabolism, with selection against almost all candidate phyla bacteria and archaea and for eukaryotes. Near complete genomes were reconstructed for three fungi placed within the Eurotiomycetes and an arthropod. While carbon fixation and sulfur oxidation were important functions in the geyser community prior to carbon addition, the organic carbon-impacted community showed enrichment for secreted proteases, secreted lipases, cellulose targeting CAZymes, and methanol oxidation. We demonstrate the broader utility of EukRep by reconstructing and evaluating relatively high-quality fungal, protist, and rotifer genomes from complex environmental samples. This approach opens the way for cultivation-independent analyses of whole microbial communities. © 2018 West et al.; Published by Cold Spring Harbor Laboratory Press.

  16. Potential of industrial biotechnology with cyanobacteria and eukaryotic microalgae.

    Science.gov (United States)

    Wijffels, René H; Kruse, Olaf; Hellingwerf, Klaas J

    2013-06-01

    Both cyanobacteria and eukaryotic microalgae are promising organisms for sustainable production of bulk products such as food, feed, materials, chemicals and fuels. In this review we will summarize the potential and current biotechnological developments. Cyanobacteria are promising host organisms for the production of small molecules that can be secreted such as ethanol, butanol, fatty acids and other organic acids. Eukaryotic microalgae are interesting for products for which cellular storage is important such as proteins, lipids, starch and alkanes. For the development of new and promising lines of production, strains of both cyanobacteria and eukaryotic microalgae have to be improved. Transformation systems have been much better developed in cyanobacteria. However, several products would be preferably produced with eukaryotic microalgae. In the case of cyanobacteria a synthetic-systems biology approach has a great potential to exploit cyanobacteria as cell factories. For eukaryotic microalgae transformation systems need to be further developed. A promising strategy is transformation of heterologous (prokaryotic and eukaryotic) genes in established eukaryotic hosts such as Chlamydomonas reinhardtii. Experimental outdoor pilots under containment for the production of genetically modified cyanobacteria and microalgae are in progress. For full scale production risks of release of genetically modified organisms need to be assessed. Copyright © 2013. Published by Elsevier Ltd.

  17. Endosymbiosis undone by stepwise elimination of the plastid in a parasitic dinoflagellate

    KAUST Repository

    Gornik, Sebastian G.

    2015-04-20

    Organelle gain through endosymbiosis has been integral to the origin and diversification of eukaryotes, and, once gained, plastids and mitochondria seem seldom lost. Indeed, discovery of nonphotosynthetic plastids in many eukaryotes - notably, the apicoplast in apicomplexan parasites such as the malaria pathogen Plasmodium - highlights the essential metabolic functions performed by plastids beyond photosynthesis. Once a cell becomes reliant on these ancillary functions, organelle dependence is apparently difficult to overcome. Previous examples of endosymbiotic organelle loss (either mitochondria or plastids), which have been invoked to explain the origin of eukaryotic diversity, have subsequently been recognized as organelle reduction to cryptic forms, such as mitosomes and apicoplasts. Integration of these ancient symbionts with their hosts has been too well developed to reverse. Here, we provide evidence that the dinoflagellate Hematodinium sp., a marine parasite of crustaceans, represents a rare case of endosymbiotic organelle loss by the elimination of the plastid. Extensive RNA and genomic sequencing data provide no evidence for a plastid organelle, but, rather, reveal a metabolic decoupling from known plastid functions that typically impede organelle loss. This independence has been achieved through retention of ancestral anabolic pathways, enzyme relocation from the plastid to the cytosol, and metabolic scavenging from the parasite\\'s host. Hematodinium sp. thus represents a further dimension of endosymbiosis-life after the organelle. © 2015, National Academy of Sciences. All rights reserved.

  18. Functions and structures of eukaryotic recombination proteins

    International Nuclear Information System (INIS)

    Ogawa, Tomoko

    1994-01-01

    We have found that Rad51 and RecA Proteins form strikingly similar structures together with dsDNA and ATP. Their right handed helical nucleoprotein filaments extend the B-form DNA double helixes to 1.5 times in length and wind the helix. The similarity and uniqueness of their structures must reflect functional homologies between these proteins. Therefore, it is highly probable that similar recombination proteins are present in various organisms of different evolutional states. We have succeeded to clone RAD51 genes from human, mouse, chicken and fission yeast genes, and found that the homologues are widely distributed in eukaryotes. The HsRad51 and MmRad51 or ChRad51 proteins consist of 339 amino acids differing only by 4 or 12 amino acids, respectively, and highly homologous to both yeast proteins, but less so to Dmcl. All of these proteins are homologous to the region from residues 33 to 240 of RecA which was named ''homologous core. The homologous core is likely to be responsible for functions common for all of them, such as the formation of helical nucleoprotein filament that is considered to be involved in homologous pairing in the recombination reaction. The mouse gene is transcribed at a high level in thymus, spleen, testis, and ovary, at lower level in brain and at a further lower level in some other tissues. It is transcribed efficiently in recombination active tissues. A clear functional difference of Rad51 homologues from RecA was suggested by the failure of heterologous genes to complement the deficiency of Scrad51 mutants. This failure seems to reflect the absence of a compatible partner, such as ScRad52 protein in the case of ScRad51 protein, between different species. Thus, these discoveries play a role of the starting point to understand the fundamental gene targeting in mammalian cells and in gene therapy. (J.P.N.)

  19. HIV-1 Replication and the Cellular Eukaryotic Translation Apparatus

    Directory of Open Access Journals (Sweden)

    Santiago Guerrero

    2015-01-01

    Full Text Available Eukaryotic translation is a complex process composed of three main steps: initiation, elongation, and termination. During infections by RNA- and DNA-viruses, the eukaryotic translation machinery is used to assure optimal viral protein synthesis. Human immunodeficiency virus type I (HIV-1 uses several non-canonical pathways to translate its own proteins, such as leaky scanning, frameshifting, shunt, and cap-independent mechanisms. Moreover, HIV-1 modulates the host translation machinery by targeting key translation factors and overcomes different cellular obstacles that affect protein translation. In this review, we describe how HIV-1 proteins target several components of the eukaryotic translation machinery, which consequently improves viral translation and replication.

  20. AUG is the only initiation codon in eukaryotes

    Energy Technology Data Exchange (ETDEWEB)

    Sherman, F; McKnight, G; Stewart, J W

    1980-01-01

    An analysis of mutants of the yeast Saccharomyces cerevisiae indicates that AUG is the sole codon capable of initiating translation of iso-1-cytochrome c. This result with yeast and the sequence results of numerous eukaryotic genes indicate that AUG is the only initiation codon in eukaryotes; in contrast, results with Escherichia colia and bacteriophages indicate that both AUG and GUG are initiation codons in prokaryotes. The difference can be explained by the lack of the t/sup 6/ A hypermodified nucleoside (N-(9-(..beta..-D-ribofuranosyl)purin-6-ylcarbamoyl)threonine) in prokaryotic initiator tRNA and its presence in eukaryotic initiator tRNA.

  1. David and Goliath: chemical perturbation of eukaryotes by bacteria.

    Science.gov (United States)

    Ho, Louis K; Nodwell, Justin R

    2016-03-01

    Environmental microbes produce biologically active small molecules that have been mined extensively as antibiotics and a smaller number of drugs that act on eukaryotic cells. It is known that there are additional bioactives to be discovered from this source. While the discovery of new antibiotics is challenged by the frequent discovery of known compounds, we contend that the eukaryote-active compounds may be less saturated. Indeed, despite there being far fewer eukaryotic-active natural products these molecules interact with a far richer diversity of molecular and cellular targets.

  2. Not all are free-living: high-throughput DNA metabarcoding reveals a diverse community of protists parasitizing soil metazoa

    NARCIS (Netherlands)

    Geisen, S.; Laros, I.; Vizcaino, A.; Bonkowski, M.; Groot, de G.A.

    2015-01-01

    Protists, the most diverse eukaryotes, are largely considered to be free-living bacterivores, but vast numbers of taxa are known to parasitize plants or animals. High-throughput sequencing (HTS) approaches now commonly replace cultivation-based approaches in studying soil protists, but insights into

  3. Enhanced transmission of drug-resistant parasites to mosquitoes following drug treatment in rodent malaria.

    Directory of Open Access Journals (Sweden)

    Andrew S Bell

    Full Text Available The evolution of drug resistant Plasmodium parasites is a major challenge to effective malaria control. In theory, competitive interactions between sensitive parasites and resistant parasites within infections are a major determinant of the rate at which parasite evolution undermines drug efficacy. Competitive suppression of resistant parasites in untreated hosts slows the spread of resistance; competitive release following treatment enhances it. Here we report that for the murine model Plasmodium chabaudi, co-infection with drug-sensitive parasites can prevent the transmission of initially rare resistant parasites to mosquitoes. Removal of drug-sensitive parasites following chemotherapy enabled resistant parasites to transmit to mosquitoes as successfully as sensitive parasites in the absence of treatment. We also show that the genetic composition of gametocyte populations in host venous blood accurately reflects the genetic composition of gametocytes taken up by mosquitoes. Our data demonstrate that, at least for this mouse model, aggressive chemotherapy leads to very effective transmission of highly resistant parasites that are present in an infection, the very parasites which undermine the long term efficacy of front-line drugs.

  4. Role of transposon-derived small RNAs in the interplay between genomes and parasitic DNA in rice.

    Directory of Open Access Journals (Sweden)

    Misuzu Nosaka

    2012-09-01

    Full Text Available RNA silencing is a defense system against "genomic parasites" such as transposable elements (TE, which are potentially harmful to host genomes. In plants, transcripts from TEs induce production of double-stranded RNAs (dsRNAs and are processed into small RNAs (small interfering RNAs, siRNAs that suppress TEs by RNA-directed DNA methylation. Thus, the majority of TEs are epigenetically silenced. On the other hand, most of the eukaryotic genome is composed of TEs and their remnants, suggesting that TEs have evolved countermeasures against host-mediated silencing. Under some circumstances, TEs can become active and increase in copy number. Knowledge is accumulating on the mechanisms of TE silencing by the host; however, the mechanisms by which TEs counteract silencing are poorly understood. Here, we show that a class of TEs in rice produces a microRNA (miRNA to suppress host silencing. Members of the microRNA820 (miR820 gene family are located within CACTA DNA transposons in rice and target a de novo DNA methyltransferase gene, OsDRM2, one of the components of epigenetic silencing. We confirmed that miR820 negatively regulates the expression of OsDRM2. In addition, we found that expression levels of various TEs are increased quite sensitively in response to decreased OsDRM2 expression and DNA methylation at TE loci. Furthermore, we found that the nucleotide sequence of miR820 and its recognition site within the target gene in some Oryza species have co-evolved to maintain their base-pairing ability. The co-evolution of these sequences provides evidence for the functionality of this regulation. Our results demonstrate how parasitic elements in the genome escape the host's defense machinery. Furthermore, our analysis of the regulation of OsDRM2 by miR820 sheds light on the action of transposon-derived small RNAs, not only as a defense mechanism for host genomes but also as a regulator of interactions between hosts and their parasitic elements.

  5. The impact of HIV-1 on the malaria parasite biomass in adults in sub-Saharan Africa contributes to the emergence of antimalarial drug resistance

    NARCIS (Netherlands)

    J.P. van Geertruyden (Jean Pierre); J. Menten (Joris); R. Colebunders (Robert); E.L. Korenromp (Eline); U. D'Alessandro (Umberto)

    2008-01-01

    textabstractBackground. HIV-related immune-suppression increases the risk of malaria (infection, disease and treatment failure) and probably the circulating parasite biomass, favoring the emergence of drug resistance parasites. Methods. The additional malaria parasite biomass related to HIV-1

  6. Numerical design and analysis of parasitic mode oscillations for 95 GHz gyrotron beam tunnel

    Science.gov (United States)

    Kumar, Nitin; Singh, Udaybir; Yadav, Vivek; Kumar, Anil; Sinha, A. K.

    2013-05-01

    The beam tunnel, equipped with the high lossy ceramics, is designed for 95 GHz gyrotron. The geometry of the beam tunnel is optimized considering the maximum RF absorption (ideally 100%) and the suppression of parasitic oscillations. The excitation of parasitic modes is a concerning problem for high frequency, high power gyrotrons. Considering the problem of parasitic mode excitation in beam tunnel, a detail analysis is performed for the suppression of these kinds of modes. Trajectory code EGUN and CST Microwave Studio are used for the simulations of electron beam trajectory and electromagnetic analysis, respectively.

  7. Potential of industrial biotechnology with cyanobacteria and eukaryotic microalgae.

    NARCIS (Netherlands)

    Wijffels, R.H.; Kruse, O.; Hellingwerf, K.J.

    2013-01-01

    Both cyanobacteria and eukaryotic microalgae are promising organisms for sustainable production of bulk products such as food, feed, materials, chemicals and fuels. In this review we will summarize the potential and current biotechnological developments. Cyanobacteria are promising host organisms

  8. Conservation and Variability of Meiosis Across the Eukaryotes.

    Science.gov (United States)

    Loidl, Josef

    2016-11-23

    Comparisons among a variety of eukaryotes have revealed considerable variability in the structures and processes involved in their meiosis. Nevertheless, conventional forms of meiosis occur in all major groups of eukaryotes, including early-branching protists. This finding confirms that meiosis originated in the common ancestor of all eukaryotes and suggests that primordial meiosis may have had many characteristics in common with conventional extant meiosis. However, it is possible that the synaptonemal complex and the delicate crossover control related to its presence were later acquisitions. Later still, modifications to meiotic processes occurred within different groups of eukaryotes. Better knowledge on the spectrum of derived and uncommon forms of meiosis will improve our understanding of many still mysterious aspects of the meiotic process and help to explain the evolutionary basis of functional adaptations to the meiotic program.

  9. DNA mismatch repair and its many roles in eukaryotic cells

    DEFF Research Database (Denmark)

    Liu, Dekang; Keijzers, Guido; Rasmussen, Lene Juel

    2017-01-01

    in the clinic, and as a biomarker of cancer susceptibility in animal model systems. Prokaryotic MMR is well-characterized at the molecular and mechanistic level; however, MMR is considerably more complex in eukaryotic cells than in prokaryotic cells, and in recent years, it has become evident that MMR plays...... novel roles in eukaryotic cells, several of which are not yet well-defined or understood. Many MMR-deficient human cancer cells lack mutations in known human MMR genes, which strongly suggests that essential eukaryotic MMR components/cofactors remain unidentified and uncharacterized. Furthermore......, the mechanism by which the eukaryotic MMR machinery discriminates between the parental (template) and the daughter (nascent) DNA strand is incompletely understood and how cells choose between the EXO1-dependent and the EXO1–independent subpathways of MMR is not known. This review summarizes recent literature...

  10. Nitrate storage and dissimilatory nitrate reduction by eukaryotic microbes

    DEFF Research Database (Denmark)

    Kamp, Anja; Høgslund, Signe; Risgaard-Petersen, Nils

    2015-01-01

    The microbial nitrogen cycle is one of the most complex and environmentally important element cycles on Earth and has long been thought to be mediated exclusively by prokaryotic microbes. Rather recently, it was discovered that certain eukaryotic microbes are able to store nitrate intracellularly......, suggesting that eukaryotes may rival prokaryotes in terms of dissimilatory nitrate reduction. Finally, this review article sketches some evolutionary perspectives of eukaryotic nitrate metabolism and identifies open questions that need to be addressed in future investigations....... and use it for dissimilatory nitrate reduction in the absence of oxygen. The paradigm shift that this entailed is ecologically significant because the eukaryotes in question comprise global players like diatoms, foraminifers, and fungi. This review article provides an unprecedented overview of nitrate...

  11. Structure and Mechanism of a Eukaryotic FMN Adenylyltransferase

    OpenAIRE

    Huerta, Carlos; Borek, Dominika; Machius, Mischa; Grishin, Nick V.; Zhang, Hong

    2009-01-01

    Flavin mononucleotide adenylyltransferase (FMNAT) catalyzes the formation of the essential flavocoenzyme FAD and plays an important role in flavocoenzyme homeostasis regulation. By sequence comparison, bacterial and eukaryotic FMNAT enzymes belong to two different protein superfamilies and apparently utilize different set of active site residues to accomplish the same chemistry. Here we report the first structural characterization of a eukaryotic FMNAT from a pathogenic yeast Candida glabrata...

  12. Massive expansion of the calpain gene family in unicellular eukaryotes

    Directory of Open Access Journals (Sweden)

    Zhao Sen

    2012-09-01

    Full Text Available Abstract Background Calpains are Ca2+-dependent cysteine proteases that participate in a range of crucial cellular processes. Dysfunction of these enzymes may cause, for instance, life-threatening diseases in humans, the loss of sex determination in nematodes and embryo lethality in plants. Although the calpain family is well characterized in animal and plant model organisms, there is a great lack of knowledge about these genes in unicellular eukaryote species (i.e. protists. Here, we study the distribution and evolution of calpain genes in a wide range of eukaryote genomes from major branches in the tree of life. Results Our investigations reveal 24 types of protein domains that are combined with the calpain-specific catalytic domain CysPc. In total we identify 41 different calpain domain architectures, 28 of these domain combinations have not been previously described. Based on our phylogenetic inferences, we propose that at least four calpain variants were established in the early evolution of eukaryotes, most likely before the radiation of all the major supergroups of eukaryotes. Many domains associated with eukaryotic calpain genes can be found among eubacteria or archaebacteria but never in combination with the CysPc domain. Conclusions The analyses presented here show that ancient modules present in prokaryotes, and a few de novo eukaryote domains, have been assembled into many novel domain combinations along the evolutionary history of eukaryotes. Some of the new calpain genes show a narrow distribution in a few branches in the tree of life, likely representing lineage-specific innovations. Hence, the functionally important classical calpain genes found among humans and vertebrates make up only a tiny fraction of the calpain family. In fact, a massive expansion of the calpain family occurred by domain shuffling among unicellular eukaryotes and contributed to a wealth of functionally different genes.

  13. Massive expansion of the calpain gene family in unicellular eukaryotes.

    Science.gov (United States)

    Zhao, Sen; Liang, Zhe; Demko, Viktor; Wilson, Robert; Johansen, Wenche; Olsen, Odd-Arne; Shalchian-Tabrizi, Kamran

    2012-09-29

    Calpains are Ca2+-dependent cysteine proteases that participate in a range of crucial cellular processes. Dysfunction of these enzymes may cause, for instance, life-threatening diseases in humans, the loss of sex determination in nematodes and embryo lethality in plants. Although the calpain family is well characterized in animal and plant model organisms, there is a great lack of knowledge about these genes in unicellular eukaryote species (i.e. protists). Here, we study the distribution and evolution of calpain genes in a wide range of eukaryote genomes from major branches in the tree of life. Our investigations reveal 24 types of protein domains that are combined with the calpain-specific catalytic domain CysPc. In total we identify 41 different calpain domain architectures, 28 of these domain combinations have not been previously described. Based on our phylogenetic inferences, we propose that at least four calpain variants were established in the early evolution of eukaryotes, most likely before the radiation of all the major supergroups of eukaryotes. Many domains associated with eukaryotic calpain genes can be found among eubacteria or archaebacteria but never in combination with the CysPc domain. The analyses presented here show that ancient modules present in prokaryotes, and a few de novo eukaryote domains, have been assembled into many novel domain combinations along the evolutionary history of eukaryotes. Some of the new calpain genes show a narrow distribution in a few branches in the tree of life, likely representing lineage-specific innovations. Hence, the functionally important classical calpain genes found among humans and vertebrates make up only a tiny fraction of the calpain family. In fact, a massive expansion of the calpain family occurred by domain shuffling among unicellular eukaryotes and contributed to a wealth of functionally different genes.

  14. Parasitic Helminths: New Weapons against Immunological Disorders

    Directory of Open Access Journals (Sweden)

    Yoshio Osada

    2010-01-01

    Full Text Available The prevalence of allergic and autoimmune diseases is increasing in developed countries, possibly due to reduced exposure to microorganisms in childhood (hygiene hypothesis. Epidemiological and experimental evidence in support of this hypothesis is accumulating. In this context, parasitic helminths are now important candidates for antiallergic/anti-inflammatory agents. Here we summarize antiallergic/anti-inflammatory effects of helminths together along with our own study of the effects of Schistosoma mansoni on Th17-dependent experimental arthritis. We also discuss possible mechanisms of helminth-induced suppression according to the recent advances of immunology.

  15. Parasitic helminths: new weapons against immunological disorders.

    Science.gov (United States)

    Osada, Yoshio; Kanazawa, Tamotsu

    2010-01-01

    The prevalence of allergic and autoimmune diseases is increasing in developed countries, possibly due to reduced exposure to microorganisms in childhood (hygiene hypothesis). Epidemiological and experimental evidence in support of this hypothesis is accumulating. In this context, parasitic helminths are now important candidates for antiallergic/anti-inflammatory agents. Here we summarize antiallergic/anti-inflammatory effects of helminths together along with our own study of the effects of Schistosoma mansoni on Th17-dependent experimental arthritis. We also discuss possible mechanisms of helminth-induced suppression according to the recent advances of immunology.

  16. Internal parasites of reptiles.

    Science.gov (United States)

    Raś-Noryńska, Małgorzata; Sokół, Rajmund

    2015-01-01

    Nowadays a growing number of exotic reptiles are kept as pets. The aim of this study was to determine the species of parasites found in reptile patients of veterinary practices in Poland. Fecal samples obtained from 76 lizards, 15 turtles and 10 snakes were examined by flotation method and direct smear stained with Lugol's iodine. In 63 samples (62.4%) the presence of parasite eggs and oocysts was revealed. Oocysts of Isospora spp. (from 33% to 100% of the samples, depending on the reptilian species) and Oxyurids eggs (10% to 75%) were predominant. In addition, isolated Eimeria spp. oocysts and Giardia intestinalis cysts were found, as well as Strongylus spp. and Hymenolepis spp. eggs. Pet reptiles are often infected with parasites, some of which are potentially dangerous to humans. A routine parasitological examination should be done in such animals.

  17. Malaria parasites: the great escape

    Directory of Open Access Journals (Sweden)

    Laurent Rénia

    2016-11-01

    Full Text Available Parasites of the genus Plasmodium have a complex life cycle. They alternate between their final mosquito host and their intermediate hosts. The parasite can be either extra- or intracellular, depending on the stage of development. By modifying their shape, motility, and metabolic requirements, the parasite adapts to the different environments in their different hosts. The parasite has evolved to escape the multiple immune mechanisms in the host that try to block parasite development at the different stages of their development. In this article, we describe the mechanisms reported thus far that allow the Plasmodium parasite to evade innate and adaptive immune responses.

  18. On the Diversification of the Translation Apparatus across Eukaryotes

    Directory of Open Access Journals (Sweden)

    Greco Hernández

    2012-01-01

    Full Text Available Diversity is one of the most remarkable features of living organisms. Current assessments of eukaryote biodiversity reaches 1.5 million species, but the true figure could be several times that number. Diversity is ingrained in all stages and echelons of life, namely, the occupancy of ecological niches, behavioral patterns, body plans and organismal complexity, as well as metabolic needs and genetics. In this review, we will discuss that diversity also exists in a key biochemical process, translation, across eukaryotes. Translation is a fundamental process for all forms of life, and the basic components and mechanisms of translation in eukaryotes have been largely established upon the study of traditional, so-called model organisms. By using modern genome-wide, high-throughput technologies, recent studies of many nonmodel eukaryotes have unveiled a surprising diversity in the configuration of the translation apparatus across eukaryotes, showing that this apparatus is far from being evolutionarily static. For some of the components of this machinery, functional differences between different species have also been found. The recent research reviewed in this article highlights the molecular and functional diversification the translational machinery has undergone during eukaryotic evolution. A better understanding of all aspects of organismal diversity is key to a more profound knowledge of life.

  19. An Evolutionary Framework for Understanding the Origin of Eukaryotes

    Directory of Open Access Journals (Sweden)

    Neil W. Blackstone

    2016-04-01

    Full Text Available Two major obstacles hinder the application of evolutionary theory to the origin of eukaryotes. The first is more apparent than real—the endosymbiosis that led to the mitochondrion is often described as “non-Darwinian” because it deviates from the incremental evolution championed by the modern synthesis. Nevertheless, endosymbiosis can be accommodated by a multi-level generalization of evolutionary theory, which Darwin himself pioneered. The second obstacle is more serious—all of the major features of eukaryotes were likely present in the last eukaryotic common ancestor thus rendering comparative methods ineffective. In addition to a multi-level theory, the development of rigorous, sequence-based phylogenetic and comparative methods represents the greatest achievement of modern evolutionary theory. Nevertheless, the rapid evolution of major features in the eukaryotic stem group requires the consideration of an alternative framework. Such a framework, based on the contingent nature of these evolutionary events, is developed and illustrated with three examples: the putative intron proliferation leading to the nucleus and the cell cycle; conflict and cooperation in the origin of eukaryotic bioenergetics; and the inter-relationship between aerobic metabolism, sterol synthesis, membranes, and sex. The modern synthesis thus provides sufficient scope to develop an evolutionary framework to understand the origin of eukaryotes.

  20. Compositional patterns in the genomes of unicellular eukaryotes.

    Science.gov (United States)

    Costantini, Maria; Alvarez-Valin, Fernando; Costantini, Susan; Cammarano, Rosalia; Bernardi, Giorgio

    2013-11-05

    The genomes of multicellular eukaryotes are compartmentalized in mosaics of isochores, large and fairly homogeneous stretches of DNA that belong to a small number of families characterized by different average GC levels, by different gene concentration (that increase with GC), different chromatin structures, different replication timing in the cell cycle, and other different properties. A question raised by these basic results concerns how far back in evolution the compartmentalized organization of the eukaryotic genomes arose. In the present work we approached this problem by studying the compositional organization of the genomes from the unicellular eukaryotes for which full sequences are available, the sample used being representative. The average GC levels of the genomes from unicellular eukaryotes cover an extremely wide range (19%-60% GC) and the compositional patterns of individual genomes are extremely different but all genomes tested show a compositional compartmentalization. The average GC range of the genomes of unicellular eukaryotes is very broad (as broad as that of prokaryotes) and individual compositional patterns cover a very broad range from very narrow to very complex. Both features are not surprising for organisms that are very far from each other both in terms of phylogenetic distances and of environmental life conditions. Most importantly, all genomes tested, a representative sample of all supergroups of unicellular eukaryotes, are compositionally compartmentalized, a major difference with prokaryotes.

  1. Limonene Arrests Parasite Development and Inhibits Isoprenylation of Proteins in Plasmodium falciparum

    Science.gov (United States)

    Moura, Ivan Cruz; Wunderlich, Gerhard; Uhrig, Maria L.; Couto, Alicia S.; Peres, Valnice J.; Katzin, Alejandro M.; Kimura, Emília A.

    2001-01-01

    Isoprenylation is an essential protein modification in eukaryotic cells. Herein, we report that in Plasmodium falciparum, a number of proteins were labeled upon incubation of intraerythrocytic forms with either [3H]farnesyl pyrophosphate or [3H]geranylgeranyl pyrophosphate. By thin-layer chromatography, we showed that attached isoprenoids are partially modified to dolichol and other, uncharacterized, residues, confirming active isoprenoid metabolism in this parasite. Incubation of blood-stage P. falciparum treated with the isoprenylation inhibitor limonene significantly decreased the parasites' progression from the ring stage to the trophozoite stage and at 1.22 mM, 50% of the parasites died after the first cycle. Using Ras- and Rap-specific monoclonal antibodies, putative Rap and Ras proteins of P. falciparum were immunoprecipitated. Upon treatment with 0.5 mM limonene, isoprenylation of these proteins was significantly decreased, possibly explaining the observed arrest of parasite development. PMID:11502528

  2. Comparative and functional genomics of Legionella identified eukaryotic like proteins as key players in host-pathogen interactions

    Directory of Open Access Journals (Sweden)

    Laura eGomez-Valero

    2011-10-01

    Full Text Available Although best known for its ability to cause severe pneumonia in people whose immune defenses are weakened, Legionella pneumophila and Legionella longbeachae are two species of a large genus of bacteria that are ubiquitous in nature, where they parasitize protozoa. Adaptation to the host environment and exploitation of host cell functions are critical for the success of these intracellular pathogens. The establishment and publication of the complete genome sequences of L. pneumophila and L. longbeachae isolates paved the way for major breakthroughs in understanding the biology of these organisms. In this review we present the knowledge gained from the analyses and comparison of the complete genome sequences of different L. pneumophila and L. longbeachae strains. Emphasis is given on putative virulence and Legionella life cycle related functions, such as the identification of an extended array of eukaryotic-like proteins, many of which have been shown to modulate host cell functions to the pathogen's advantage. Surprisingly, many of the eukaryotic domain proteins identified in L. pneumophila as well as many substrates of the Dot/Icm type IV secretion system essential for intracellular replication are different between these two species, although they cause the same disease. Finally, evolutionary aspects regarding the eukaryotic like proteins in Legionella are discussed.

  3. Deciphering the ubiquitin-mediated pathway in apicomplexan parasites: a potential strategy to interfere with parasite virulence.

    Science.gov (United States)

    Ponts, Nadia; Yang, Jianfeng; Chung, Duk-Won Doug; Prudhomme, Jacques; Girke, Thomas; Horrocks, Paul; Le Roch, Karine G

    2008-06-11

    Reversible modification of proteins through the attachment of ubiquitin or ubiquitin-like modifiers is an essential post-translational regulatory mechanism in eukaryotes. The conjugation of ubiquitin or ubiquitin-like proteins has been demonstrated to play roles in growth, adaptation and homeostasis in all eukaryotes, with perturbation of ubiquitin-mediated systems associated with the pathogenesis of many human diseases, including cancer and neurodegenerative disorders. Here we describe the use of an HMM search of functional Pfam domains found in the key components of the ubiquitin-mediated pathway necessary to activate and reversibly modify target proteins in eight apicomplexan parasitic protozoa for which complete or late-stage genome projects exist. In parallel, the same search was conducted on five model organisms, single-celled and metazoans, to generate data to validate both the search parameters employed and aid paralog classification in Apicomplexa. For each of the 13 species investigated, a set of proteins predicted to be involved in the ubiquitylation pathway has been identified and demonstrates increasing component members of the ubiquitylation pathway correlating with organism and genome complexity. Sequence homology and domain architecture analyses facilitated prediction of apicomplexan-specific protein function, particularly those involved in regulating cell division during these parasite's complex life cycles. This study provides a comprehensive analysis of proteins predicted to be involved in the apicomplexan ubiquitin-mediated pathway. Given the importance of such pathway in a wide variety of cellular processes, our data is a key step in elucidating the biological networks that, in part, direct the pathogenicity of these parasites resulting in a massive impact on global health. Moreover, apicomplexan-specific adaptations of the ubiquitylation pathway may represent new therapeutic targets for much needed drugs against apicomplexan parasites.

  4. mRNA export in the apicomplexan parasite Toxoplasma gondii: emerging divergent components of a crucial pathway.

    Science.gov (United States)

    Ávila, Andréa Rodrigues; Cabezas-Cruz, Alexjandro; Gissot, Mathieu

    2018-01-25

    Control of gene expression is crucial for parasite survival and is the result of a series of processes that are regulated to permit fine-tuning of gene expression in response to biological changes during the life-cycle of apicomplexan parasites. Control of mRNA nuclear export is a key process in eukaryotic cells but is poorly understood in apicomplexan parasites. Here, we review recent knowledge regarding this process with an emphasis on T. gondii. We describe the presence of divergent orthologs and discuss structural and functional differences in export factors between apicomplexans and other eukaryotic lineages. Undoubtedly, the use of the CRISPR/Cas9 system in high throughput screenings associated with the discovery of mRNA nuclear export complexes by proteomic analysis will contribute to identify these divergent factors. Ligand-based or structure-based strategies may be applied to investigate the potential use of these proteins as targets for new antiprotozoal agents.

  5. Dormant origins as a built-in safeguard in eukaryotic DNA replication against genome instability and disease development.

    Science.gov (United States)

    Shima, Naoko; Pederson, Kayla D

    2017-08-01

    DNA replication is a prerequisite for cell proliferation, yet it can be increasingly challenging for a eukaryotic cell to faithfully duplicate its genome as its size and complexity expands. Dormant origins now emerge as a key component for cells to successfully accomplish such a demanding but essential task. In this perspective, we will first provide an overview of the fundamental processes eukaryotic cells have developed to regulate origin licensing and firing. With a special focus on mammalian systems, we will then highlight the role of dormant origins in preventing replication-associated genome instability and their functional interplay with proteins involved in the DNA damage repair response for tumor suppression. Lastly, deficiencies in the origin licensing machinery will be discussed in relation to their influence on stem cell maintenance and human diseases. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Transcriptionally Driven DNA Replication Program of the Human Parasite Leishmania major

    Directory of Open Access Journals (Sweden)

    Rodrigo Lombraña

    2016-08-01

    Full Text Available Faithful inheritance of eukaryotic genomes requires the orchestrated activation of multiple DNA replication origins (ORIs. Although origin firing is mechanistically conserved, how origins are specified and selected for activation varies across different model systems. Here, we provide a complete analysis of the nucleosomal landscape and replication program of the human parasite Leishmania major, building on a better evolutionary understanding of replication organization in Eukarya. We found that active transcription is a driving force for the nucleosomal organization of the L. major genome and that both the spatial and the temporal program of DNA replication can be explained as associated to RNA polymerase kinetics. This simple scenario likely provides flexibility and robustness to deal with the environmental changes that impose alterations in the genetic programs during parasitic life cycle stages. Our findings also suggest that coupling replication initiation to transcription elongation could be an ancient solution used by eukaryotic cells for origin maintenance.

  7. Unique physiology of host-parasite interactions in microsporidia infections.

    Science.gov (United States)

    Williams, Bryony A P

    2009-11-01

    Microsporidia are intracellular parasites of all major animal lineages and have a described diversity of over 1200 species and an actual diversity that is estimated to be much higher. They are important pathogens of mammals, and are now one of the most common infections among immunocompromised humans. Although related to fungi, microsporidia are atypical in genomic biology, cell structure and infection mechanism. Host cell infection involves the rapid expulsion of a polar tube from a dormant spore to pierce the host cell membrane and allow the direct transfer of the spore contents into the host cell cytoplasm. This intimate relationship between parasite and host is unique. It allows the microsporidia to be highly exploitative of the host cell environment and cause such diverse effects as the induction of hypertrophied cells to harbour prolific spore development, host sex ratio distortion and host cell organelle and microtubule reorganization. Genome sequencing has revealed that microsporidia have achieved this high level of parasite sophistication with radically reduced proteomes and with many typical eukaryotic pathways pared-down to what appear to be minimal functional units. These traits make microsporidia intriguing model systems for understanding the extremes of reductive parasite evolution and host cell manipulation.

  8. Past Intestinal Parasites.

    Science.gov (United States)

    Le Bailly, Matthieu; Araújo, Adauto

    2016-08-01

    This chapter aims to provide some key points for researchers interested in the study of ancient gastrointestinal parasites. These few pages are dedicated to my colleague and friend, Prof. Adauto Araújo (1951-2015), who participated in the writing of this chapter. His huge efforts in paleoparasitology contributed to the development and promotion of the discipline during more than 30 years.

  9. Enteric parasites and AIDS

    Directory of Open Access Journals (Sweden)

    Sérgio Cimerman

    1999-11-01

    Full Text Available OBJECTIVE: To report on the importance of intestinal parasites in patients with AIDS, showing relevant data in the medical literature, with special emphasis on epidemiology, diagnosis and treatment of enteroparasitosis, especially cryptosporidiasis, isosporiasis, microsporidiasis and strongyloidiasis. DESIGN: Narrative review.

  10. A parasitic selfish gene that affects host promiscuity.

    Science.gov (United States)

    Giraldo-Perez, Paulina; Goddard, Matthew R

    2013-11-07

    Selfish genes demonstrate transmission bias and invade sexual populations despite conferring no benefit to their hosts. While the molecular genetics and evolutionary dynamics of selfish genes are reasonably well characterized, their effects on hosts are not. Homing endonuclease genes (HEGs) are one well-studied family of selfish genes that are assumed to be benign. However, we show that carrying HEGs is costly for Saccharomyces cerevisiae, demonstrating that these genetic elements are not necessarily benign but maybe parasitic. We estimate a selective load of approximately 1-2% in 'natural' niches. The second aspect we examine is the ability of HEGs to affect hosts' sexual behaviour. As all selfish genes critically rely on sex for spread, then any selfish gene correlated with increased host sexuality will enjoy a transmission advantage. While classic parasites are known to manipulate host behaviour, we are not aware of any evidence showing a selfish gene is capable of affecting host promiscuity. The data presented here show a selfish element may increase the propensity of its eukaryote host to undergo sex and along with increased rates of non-Mendelian inheritance, this may counterbalance mitotic selective load and promote spread. Demonstration that selfish genes are correlated with increased promiscuity in eukaryotes connects with ideas suggesting that selfish genes promoted the evolution of sex initially.

  11. A broad distribution of the alternative oxidase in microsporidian parasites.

    Directory of Open Access Journals (Sweden)

    Bryony A P Williams

    2010-02-01

    Full Text Available Microsporidia are a group of obligate intracellular parasitic eukaryotes that were considered to be amitochondriate until the recent discovery of highly reduced mitochondrial organelles called mitosomes. Analysis of the complete genome of Encephalitozoon cuniculi revealed a highly reduced set of proteins in the organelle, mostly related to the assembly of iron-sulphur clusters. Oxidative phosphorylation and the Krebs cycle proteins were absent, in keeping with the notion that the microsporidia and their mitosomes are anaerobic, as is the case for other mitosome bearing eukaryotes, such as Giardia. Here we provide evidence opening the possibility that mitosomes in a number of microsporidian lineages are not completely anaerobic. Specifically, we have identified and characterized a gene encoding the alternative oxidase (AOX, a typically mitochondrial terminal oxidase in eukaryotes, in the genomes of several distantly related microsporidian species, even though this gene is absent from the complete genome of E. cuniculi. In order to confirm that these genes encode functional proteins, AOX genes from both A. locustae and T. hominis were over-expressed in E. coli and AOX activity measured spectrophotometrically using ubiquinol-1 (UQ-1 as substrate. Both A. locustae and T. hominis AOX proteins reduced UQ-1 in a cyanide and antimycin-resistant manner that was sensitive to ascofuranone, a potent inhibitor of the trypanosomal AOX. The physiological role of AOX microsporidia may be to reoxidise reducing equivalents produced by glycolysis, in a manner comparable to that observed in trypanosomes.

  12. Archaeal “Dark Matter” and the Origin of Eukaryotes

    Science.gov (United States)

    Williams, Tom A.; Embley, T. Martin

    2014-01-01

    Current hypotheses about the history of cellular life are mainly based on analyses of cultivated organisms, but these represent only a small fraction of extant biodiversity. The sequencing of new environmental lineages therefore provides an opportunity to test, revise, or reject existing ideas about the tree of life and the origin of eukaryotes. According to the textbook three domains hypothesis, the eukaryotes emerge as the sister group to a monophyletic Archaea. However, recent analyses incorporating better phylogenetic models and an improved sampling of the archaeal domain have generally supported the competing eocyte hypothesis, in which core genes of eukaryotic cells originated from within the Archaea, with important implications for eukaryogenesis. Given this trend, it was surprising that a recent analysis incorporating new genomes from uncultivated Archaea recovered a strongly supported three domains tree. Here, we show that this result was due in part to the use of a poorly fitting phylogenetic model and also to the inclusion by an automated pipeline of genes of putative bacterial origin rather than nucleocytosolic versions for some of the eukaryotes analyzed. When these issues were resolved, analyses including the new archaeal lineages placed core eukaryotic genes within the Archaea. These results are consistent with a number of recent studies in which improved archaeal sampling and better phylogenetic models agree in supporting the eocyte tree over the three domains hypothesis. PMID:24532674

  13. Evolution of DNA replication protein complexes in eukaryotes and Archaea.

    Directory of Open Access Journals (Sweden)

    Nicholas Chia

    Full Text Available BACKGROUND: The replication of DNA in Archaea and eukaryotes requires several ancillary complexes, including proliferating cell nuclear antigen (PCNA, replication factor C (RFC, and the minichromosome maintenance (MCM complex. Bacterial DNA replication utilizes comparable proteins, but these are distantly related phylogenetically to their archaeal and eukaryotic counterparts at best. METHODOLOGY/PRINCIPAL FINDINGS: While the structures of each of the complexes do not differ significantly between the archaeal and eukaryotic versions thereof, the evolutionary dynamic in the two cases does. The number of subunits in each complex is constant across all taxa. However, they vary subtly with regard to composition. In some taxa the subunits are all identical in sequence, while in others some are homologous rather than identical. In the case of eukaryotes, there is no phylogenetic variation in the makeup of each complex-all appear to derive from a common eukaryotic ancestor. This is not the case in Archaea, where the relationship between the subunits within each complex varies taxon-to-taxon. We have performed a detailed phylogenetic analysis of these relationships in order to better understand the gene duplications and divergences that gave rise to the homologous subunits in Archaea. CONCLUSION/SIGNIFICANCE: This domain level difference in evolution suggests that different forces have driven the evolution of DNA replication proteins in each of these two domains. In addition, the phylogenies of all three gene families support the distinctiveness of the proposed archaeal phylum Thaumarchaeota.

  14. Endosymbiosis undone by stepwise elimination of the plastid in a parasitic dinoflagellate

    KAUST Repository

    Gornik, Sebastian G.; Febrimarsa,; Cassin, Andrew M.; MacRae, James I.; Ramaprasad, Abhinay; Rchiad, ‍ Zineb; McConville, Malcolm J.; Bacic, Antony; McFadden, Geoffrey I.; Pain, Arnab; Waller, Ross F.

    2015-01-01

    Organelle gain through endosymbiosis has been integral to the origin and diversification of eukaryotes, and, once gained, plastids and mitochondria seem seldom lost. Indeed, discovery of nonphotosynthetic plastids in many eukaryotes - notably, the apicoplast in apicomplexan parasites such as the malaria pathogen Plasmodium - highlights the essential metabolic functions performed by plastids beyond photosynthesis. Once a cell becomes reliant on these ancillary functions, organelle dependence is apparently difficult to overcome. Previous examples of endosymbiotic organelle loss (either mitochondria or plastids), which have been invoked to explain the origin of eukaryotic diversity, have subsequently been recognized as organelle reduction to cryptic forms, such as mitosomes and apicoplasts. Integration of these ancient symbionts with their hosts has been too well developed to reverse. Here, we provide evidence that the dinoflagellate Hematodinium sp., a marine parasite of crustaceans, represents a rare case of endosymbiotic organelle loss by the elimination of the plastid. Extensive RNA and genomic sequencing data provide no evidence for a plastid organelle, but, rather, reveal a metabolic decoupling from known plastid functions that typically impede organelle loss. This independence has been achieved through retention of ancestral anabolic pathways, enzyme relocation from the plastid to the cytosol, and metabolic scavenging from the parasite's host. Hematodinium sp. thus represents a further dimension of endosymbiosis-life after the organelle. © 2015, National Academy of Sciences. All rights reserved.

  15. Calcium signaling in closely related protozoan groups (Alveolata): non-parasitic ciliates (Paramecium, Tetrahymena) vs. parasitic Apicomplexa (Plasmodium, Toxoplasma).

    Science.gov (United States)

    Plattner, H; Sehring, I M; Mohamed, I K; Miranda, K; De Souza, W; Billington, R; Genazzani, A; Ladenburger, E-M

    2012-05-01

    The importance of Ca2+-signaling for many subcellular processes is well established in higher eukaryotes, whereas information about protozoa is restricted. Recent genome analyses have stimulated such work also with Alveolates, such as ciliates (Paramecium, Tetrahymena) and their pathogenic close relatives, the Apicomplexa (Plasmodium, Toxoplasma). Here we compare Ca2+ signaling in the two closely related groups. Acidic Ca2+ stores have been characterized in detail in Apicomplexa, but hardly in ciliates. Two-pore channels engaged in Ca2+-release from acidic stores in higher eukaryotes have not been stingently characterized in either group. Both groups are endowed with plasma membrane- and endoplasmic reticulum-type Ca2+-ATPases (PMCA, SERCA), respectively. Only recently was it possible to identify in Paramecium a number of homologs of ryanodine and inositol 1,3,4-trisphosphate receptors (RyR, IP3R) and to localize them to widely different organelles participating in vesicle trafficking. For Apicomplexa, physiological experiments suggest the presence of related channels although their identity remains elusive. In Paramecium, IP3Rs are constitutively active in the contractile vacuole complex; RyR-related channels in alveolar sacs are activated during exocytosis stimulation, whereas in the parasites the homologous structure (inner membrane complex) may no longer function as a Ca2+ store. Scrutinized comparison of the two closely related protozoan phyla may stimulate further work and elucidate adaptation to parasitic life. See also "Conclusions" section. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Role of parasites in cancer.

    Science.gov (United States)

    Mandong, B M; Ngbea, J A; Raymond, Vhriterhire

    2013-01-01

    In areas of parasitic endemicity, the occurrence of cancer that is not frequent may be linked with parasitic infection. Epidemiological correlates between some parasitic infections and cancer is strong, suggesting a strong aetiological association. The common parasites associated with human cancers are schistosomiasis, malaria, liver flukes (Clonorchis sinenses, Opistorchis viverrini). To review the pathology, literature and methods of diagnosis. Literature review from peer reviewed Journals cited in PubMed and local journals. Parasites may serve as promoters of cancer in endemic areas of infection.

  17. Role of the Ubiquitin-Proteasome Systems in the Biology and Virulence of Protozoan Parasites

    Directory of Open Access Journals (Sweden)

    Christian Muñoz

    2015-01-01

    Full Text Available In eukaryotic cells, proteasomes perform crucial roles in many cellular pathways by degrading proteins to enforce quality control and regulate many cellular processes such as cell cycle progression, signal transduction, cell death, immune responses, metabolism, protein-quality control, and development. The catalytic heart of these complexes, the 20S proteasome, is highly conserved in bacteria, yeast, and humans. However, until a few years ago, the role of proteasomes in parasite biology was completely unknown. Here, we summarize findings about the role of proteasomes in protozoan parasites biology and virulence. Several reports have confirmed the role of proteasomes in parasite biological processes such as cell differentiation, cell cycle, proliferation, and encystation. Proliferation and cell differentiation are key steps in host colonization. Considering the importance of proteasomes in both processes in many different parasites such as Trypanosoma, Leishmania, Toxoplasma, and Entamoeba, parasite proteasomes might serve as virulence factors. Several pieces of evidence strongly suggest that the ubiquitin-proteasome pathway is also a viable parasitic therapeutic target. Research in recent years has shown that the proteasome is a valid drug target for sleeping sickness and malaria. Then, proteasomes are a key organelle in parasite biology and virulence and appear to be an attractive new chemotherapeutic target.

  18. Interaction of tRNA with Eukaryotic Ribosome

    Directory of Open Access Journals (Sweden)

    Dmitri Graifer

    2015-03-01

    Full Text Available This paper is a review of currently available data concerning interactions of tRNAs with the eukaryotic ribosome at various stages of translation. These data include the results obtained by means of cryo-electron microscopy and X-ray crystallography applied to various model ribosomal complexes, site-directed cross-linking with the use of tRNA derivatives bearing chemically or photochemically reactive groups in the CCA-terminal fragment and chemical probing of 28S rRNA in the region of the peptidyl transferase center. Similarities and differences in the interactions of tRNAs with prokaryotic and eukaryotic ribosomes are discussed with concomitant consideration of the extent of resemblance between molecular mechanisms of translation in eukaryotes and bacteria.

  19. Gain media edge treatment to suppress amplified spontaneous emission in a high power laser

    Science.gov (United States)

    Hackel, Lloyd A.; Soules, Thomas F.; Fochs, Scott N.; Rotter, Mark D.; Letts, Stephan A.

    2008-12-09

    A novel method and apparatus for suppressing ASE and parasitic oscillation modes in a high average power laser is introduced. By roughening one or more peripheral edges of a solid-state crystal or ceramic laser gain media and by bonding such edges using a substantially high index bonding elastomer or epoxy to a predetermined electromagnetic absorbing arranged adjacent to the entire outer surface of the peripheral edges of the roughened laser gain media, ASE and parasitic oscillation modes can be effectively suppressed.

  20. Drug target prediction and prioritization: using orthology to predict essentiality in parasite genomes

    Directory of Open Access Journals (Sweden)

    Hall Ross S

    2010-04-01

    Full Text Available Abstract Background New drug targets are urgently needed for parasites of socio-economic importance. Genes that are essential for parasite survival are highly desirable targets, but information on these genes is lacking, as gene knockouts or knockdowns are difficult to perform in many species of parasites. We examined the applicability of large-scale essentiality information from four model eukaryotes, Caenorhabditis elegans, Drosophila melanogaster, Mus musculus and Saccharomyces cerevisiae, to discover essential genes in each of their genomes. Parasite genes that lack orthologues in their host are desirable as selective targets, so we also examined prediction of essential genes within this subset. Results Cross-species analyses showed that the evolutionary conservation of genes and the presence of essential orthologues are each strong predictors of essentiality in eukaryotes. Absence of paralogues was also found to be a general predictor of increased relative essentiality. By combining several orthology and essentiality criteria one can select gene sets with up to a five-fold enrichment in essential genes compared with a random selection. We show how quantitative application of such criteria can be used to predict a ranked list of potential drug targets from Ancylostoma caninum and Haemonchus contortus - two blood-feeding strongylid nematodes, for which there are presently limited sequence data but no functional genomic tools. Conclusions The present study demonstrates the utility of using orthology information from multiple, diverse eukaryotes to predict essential genes. The data also emphasize the challenge of identifying essential genes among those in a parasite that are absent from its host.

  1. Arabidopsis transcription factors: genome-wide comparative analysis among eukaryotes.

    Science.gov (United States)

    Riechmann, J L; Heard, J; Martin, G; Reuber, L; Jiang, C; Keddie, J; Adam, L; Pineda, O; Ratcliffe, O J; Samaha, R R; Creelman, R; Pilgrim, M; Broun, P; Zhang, J Z; Ghandehari, D; Sherman, B K; Yu, G

    2000-12-15

    The completion of the Arabidopsis thaliana genome sequence allows a comparative analysis of transcriptional regulators across the three eukaryotic kingdoms. Arabidopsis dedicates over 5% of its genome to code for more than 1500 transcription factors, about 45% of which are from families specific to plants. Arabidopsis transcription factors that belong to families common to all eukaryotes do not share significant similarity with those of the other kingdoms beyond the conserved DNA binding domains, many of which have been arranged in combinations specific to each lineage. The genome-wide comparison reveals the evolutionary generation of diversity in the regulation of transcription.

  2. Eukaryotic ribosome display with in situ DNA recovery.

    Science.gov (United States)

    He, Mingyue; Edwards, Bryan M; Kastelic, Damjana; Taussig, Michael J

    2012-01-01

    Ribosome display is a cell-free display technology for in vitro selection and optimisation of proteins from large diversified libraries. It operates through the formation of stable protein-ribosome-mRNA (PRM) complexes and selection of ligand-binding proteins, followed by DNA recovery from the selected genetic information. Both prokaryotic and eukaryotic ribosome display systems have been developed. In this chapter, we describe the eukaryotic rabbit reticulocyte method in which a distinct in situ single-primer RT-PCR procedure is used to recover DNA from the selected PRM complexes without the need for prior disruption of the ribosome.

  3. Characterization of prokaryotic and eukaryotic promoters usinghidden Markov models

    DEFF Research Database (Denmark)

    Pedersen, Anders Gorm; Baldi, Pierre; Brunak, Søren

    1996-01-01

    In this paper we utilize hidden Markov models (HMMs) and information theory to analyze prokaryotic and eukaryotic promoters. We perform this analysis with special emphasis on the fact that promoters are divided into a number of different classes, depending on which polymerase-associated factors...... that bind to them. We find that HMMs trained on such subclasses of Escherichia coli promoters (specifically, the so-called sigma-70 and sigma-54 classes) give an excellent classification of unknown promoters with respect to sigma-class. HMMs trained on eukaryotic sequences from human genes also model nicely...

  4. Characterization of prokaryotic and eukaryotic promoters using hidden Markov models

    DEFF Research Database (Denmark)

    Pedersen, Anders Gorm; Baldi, P.; Chauvin, Y.

    1996-01-01

    In this paper we utilize hidden Markov models (HMMs) and information theory to analyze prokaryotic and eukaryotic promoters. We perform this analysis with special emphasis on the fact that promoters are divided into a number of different classes, depending on which polymerase-associated factors...... that bind to them. We find that HMMs trained on such subclasses of Escherichia coli promoters (specifically, the so-called sigma 70 and sigma 54 classes) give an excellent classification of unknown promoters with respect to sigma-class. HMMs trained on eukaryotic sequences from human genes also model nicely...

  5. Surface antigens and potential virulence factors from parasites detected by comparative genomics of perfect amino acid repeats

    Directory of Open Access Journals (Sweden)

    Adler Joël

    2007-12-01

    Full Text Available Abstract Background Many parasitic organisms, eukaryotes as well as bacteria, possess surface antigens with amino acid repeats. Making up the interface between host and pathogen such repetitive proteins may be virulence factors involved in immune evasion or cytoadherence. They find immunological applications in serodiagnostics and vaccine development. Here we use proteins which contain perfect repeats as a basis for comparative genomics between parasitic and free-living organisms. Results We have developed Reptile http://reptile.unibe.ch, a program for proteome-wide probabilistic description of perfect repeats in proteins. Parasite proteomes exhibited a large variance regarding the proportion of repeat-containing proteins. Interestingly, there was a good correlation between the percentage of highly repetitive proteins and mean protein length in parasite proteomes, but not at all in the proteomes of free-living eukaryotes. Reptile combined with programs for the prediction of transmembrane domains and GPI-anchoring resulted in an effective tool for in silico identification of potential surface antigens and virulence factors from parasites. Conclusion Systemic surveys for perfect amino acid repeats allowed basic comparisons between free-living and parasitic organisms that were directly applicable to predict proteins of serological and parasitological importance. An on-line tool is available at http://genomics.unibe.ch/dora.

  6. Distinct gene number-genome size relationships for eukaryotes and non-eukaryotes: gene content estimation for dinoflagellate genomes.

    Directory of Open Access Journals (Sweden)

    Yubo Hou

    Full Text Available The ability to predict gene content is highly desirable for characterization of not-yet sequenced genomes like those of dinoflagellates. Using data from completely sequenced and annotated genomes from phylogenetically diverse lineages, we investigated the relationship between gene content and genome size using regression analyses. Distinct relationships between log(10-transformed protein-coding gene number (Y' versus log(10-transformed genome size (X', genome size in kbp were found for eukaryotes and non-eukaryotes. Eukaryotes best fit a logarithmic model, Y' = ln(-46.200+22.678X', whereas non-eukaryotes a linear model, Y' = 0.045+0.977X', both with high significance (p0.91. Total gene number shows similar trends in both groups to their respective protein coding regressions. The distinct correlations reflect lower and decreasing gene-coding percentages as genome size increases in eukaryotes (82%-1% compared to higher and relatively stable percentages in prokaryotes and viruses (97%-47%. The eukaryotic regression models project that the smallest dinoflagellate genome (3x10(6 kbp contains 38,188 protein-coding (40,086 total genes and the largest (245x10(6 kbp 87,688 protein-coding (92,013 total genes, corresponding to 1.8% and 0.05% gene-coding percentages. These estimates do not likely represent extraordinarily high functional diversity of the encoded proteome but rather highly redundant genomes as evidenced by high gene copy numbers documented for various dinoflagellate species.

  7. An algorithm for detecting eukaryotic sequences in metagenomic ...

    Indian Academy of Sciences (India)

    species but also from accidental contamination from the genome of eukaryotic host cells. The latter scenario generally occurs in the case of host-associated metagenomes, e.g. microbes living in human gut. In such cases, one needs to identify and remove contaminating host DNA sequences, since the latter sequences will ...

  8. Potential of industrial biotechnology with cyanobacteria and eukaryotic microalgae

    NARCIS (Netherlands)

    Wijffels, R.H.; Kruse, O.; Hellingwerf, K.J.

    2013-01-01

    Both cyanobacteria and eukaryotic microalgae are promising organisms for sustainable production of bulk products such as food, feed, materials, chemicals and fuels. In this review we will summarize the potential and current biotechnological developments.Cyanobacteria are promising host organisms for

  9. A Synthetic Biology Framework for Programming Eukaryotic Transcription Functions

    Science.gov (United States)

    Khalil, Ahmad S.; Lu, Timothy K.; Bashor, Caleb J.; Ramirez, Cherie L.; Pyenson, Nora C.; Joung, J. Keith; Collins, James J.

    2013-01-01

    SUMMARY Eukaryotic transcription factors (TFs) perform complex and combinatorial functions within transcriptional networks. Here, we present a synthetic framework for systematically constructing eukaryotic transcription functions using artificial zinc fingers, modular DNA-binding domains found within many eukaryotic TFs. Utilizing this platform, we construct a library of orthogonal synthetic transcription factors (sTFs) and use these to wire synthetic transcriptional circuits in yeast. We engineer complex functions, such as tunable output strength and transcriptional cooperativity, by rationally adjusting a decomposed set of key component properties, e.g., DNA specificity, affinity, promoter design, protein-protein interactions. We show that subtle perturbations to these properties can transform an individual sTF between distinct roles (activator, cooperative factor, inhibitory factor) within a transcriptional complex, thus drastically altering the signal processing behavior of multi-input systems. This platform provides new genetic components for synthetic biology and enables bottom-up approaches to understanding the design principles of eukaryotic transcriptional complexes and networks. PMID:22863014

  10. Geminin: a major DNA replication safeguard in higher eukaryotes

    DEFF Research Database (Denmark)

    Melixetian, Marina; Helin, Kristian

    2004-01-01

    Eukaryotes have evolved multiple mechanisms to restrict DNA replication to once per cell cycle. These mechanisms prevent relicensing of origins of replication after initiation of DNA replication in S phase until the end of mitosis. Most of our knowledge of mechanisms controlling prereplication...

  11. Eu-Detect: An algorithm for detecting eukaryotic sequences in ...

    Indian Academy of Sciences (India)

    Supplementary figure 1. Plots depicting the classification accuracy of Eu-Detect with various combinations of. 'cumulative sequence count' (40K, 50K, 60K, 70K, 80K) and 'coverage threshold' (20%, 30%, 40%, 50%, 60%, 70%,. 80%). While blue bars represent Eu-Detect's average classification accuracy with eukaryotic ...

  12. Uncoupling of Sister Replisomes during Eukaryotic DNA Replication

    NARCIS (Netherlands)

    Yardimci, Hasan; Loveland, Anna B.; Habuchi, Satoshi; van Oijen, Antoine M.; Walter, Johannes C.

    2010-01-01

    The duplication of eukaryotic genomes involves the replication of DNA from multiple origins of replication. In S phase, two sister replisomes assemble at each active origin, and they replicate DNA in opposite directions. Little is known about the functional relationship between sister replisomes.

  13. Data from: Not all are free-living: high-throughput DNA metabarcoding reveals a diverse community of protists parasitizing soil metazoa

    NARCIS (Netherlands)

    Geisen, Stefan; Laros, I.; Vizcaino, A.; Bonkowski, M.; Groot, de G.A.

    2015-01-01

    Protists, the most diverse eukaryotes, are largely considered to be free-living bacterivores, but vast numbers of taxa are known to parasitize plants or animals. High-throughput sequencing (HTS) approaches now commonly replace cultivation-based approaches in studying soil protists, but insights into

  14. Uniting sex and eukaryote origins in an emerging oxygenic world.

    Science.gov (United States)

    Gross, Jeferson; Bhattacharya, Debashish

    2010-08-23

    Theories about eukaryote origins (eukaryogenesis) need to provide unified explanations for the emergence of diverse complex features that define this lineage. Models that propose a prokaryote-to-eukaryote transition are gridlocked between the opposing "phagocytosis first" and "mitochondria as seed" paradigms, neither of which fully explain the origins of eukaryote cell complexity. Sex (outcrossing with meiosis) is an example of an elaborate trait not yet satisfactorily addressed in theories about eukaryogenesis. The ancestral nature of meiosis and its dependence on eukaryote cell biology suggest that the emergence of sex and eukaryogenesis were simultaneous and synergic and may be explained by a common selective pressure. We propose that a local rise in oxygen levels, due to cyanobacterial photosynthesis in ancient Archean microenvironments, was highly toxic to the surrounding biota. This selective pressure drove the transformation of an archaeal (archaebacterial) lineage into the first eukaryotes. Key is that oxygen might have acted in synergy with environmental stresses such as ultraviolet (UV) radiation and/or desiccation that resulted in the accumulation of reactive oxygen species (ROS). The emergence of eukaryote features such as the endomembrane system and acquisition of the mitochondrion are posited as strategies to cope with a metabolic crisis in the cell plasma membrane and the accumulation of ROS, respectively. Selective pressure for efficient repair of ROS/UV-damaged DNA drove the evolution of sex, which required cell-cell fusions, cytoskeleton-mediated chromosome movement, and emergence of the nuclear envelope. Our model implies that evolution of sex and eukaryogenesis were inseparable processes. Several types of data can be used to test our hypothesis. These include paleontological predictions, simulation of ancient oxygenic microenvironments, and cell biological experiments with Archaea exposed to ROS and UV stresses. Studies of archaeal conjugation

  15. Patterns of intron gain and conservation in eukaryotic genes

    Directory of Open Access Journals (Sweden)

    Wolf Yuri I

    2007-10-01

    Full Text Available Abstract Background: The presence of introns in protein-coding genes is a universal feature of eukaryotic genome organization, and the genes of multicellular eukaryotes, typically, contain multiple introns, a substantial fraction of which share position in distant taxa, such as plants and animals. Depending on the methods and data sets used, researchers have reached opposite conclusions on the causes of the high fraction of shared introns in orthologous genes from distant eukaryotes. Some studies conclude that shared intron positions reflect, almost entirely, a remarkable evolutionary conservation, whereas others attribute it to parallel gain of introns. To resolve these contradictions, it is crucial to analyze the evolution of introns by using a model that minimally relies on arbitrary assumptions. Results: We developed a probabilistic model of evolution that allows for variability of intron gain and loss rates over branches of the phylogenetic tree, individual genes, and individual sites. Applying this model to an extended set of conserved eukaryotic genes, we find that parallel gain, on average, accounts for only ~8% of the shared intron positions. However, the distribution of parallel gains over the phylogenetic tree of eukaryotes is highly non-uniform. There are, practically, no parallel gains in closely related lineages, whereas for distant lineages, such as animals and plants, parallel gains appear to contribute up to 20% of the shared intron positions. In accord with these findings, we estimated that ancestral introns have a high probability to be retained in extant genomes, and conversely, that a substantial fraction of extant introns have retained their positions since the early stages of eukaryotic evolution. In addition, the density of sites that are available for intron insertion is estimated to be, approximately, one in seven basepairs. Conclusion: We obtained robust estimates of the contribution of parallel gain to the observed

  16. Parasitic worms: how many really?

    Science.gov (United States)

    Strona, Giovanni; Fattorini, Simone

    2014-04-01

    Accumulation curves are useful tools to estimate species diversity. Here we argue that they can also be used in the study of global parasite species richness. Although this basic idea is not completely new, our approach differs from the previous ones as it treats each host species as an independent sample. We show that randomly resampling host-parasite records from the existing databases makes it possible to empirically model the relationship between the number of investigated host species, and the corresponding number of parasite species retrieved from those hosts. This method was tested on 21 inclusive lists of parasitic worms occurring on vertebrate hosts. All of the obtained models conform well to a power law curve. These curves were then used to estimate global parasite species richness. Results obtained with the new method suggest that current predictions are likely to severely overestimate parasite diversity. Copyright © 2014 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

  17. Quantum-mechanical suppression of bremsstrahlung

    Energy Technology Data Exchange (ETDEWEB)

    Becker-Szendy, R.; Keller, L.; Niemi, G.; Perl, M.; Rochester, L. [Stanford Univ., CA (United States); Anthony, P. [Stanford Univ., CA (United States)]|[Lawrence Livermore National Lab., CA (United States); Bosted, P. [American Univ., Washington, DC (United States); Cavalli-Sforza, M.; Kelley, L.; Klein, S. [Univ. of California, Santa Cruz, CA (United States)] [and others

    1994-12-01

    The authors have studied quantum-mechanical suppression of bremsstrahlung of low-energy 1-500 MeV photons from high-energy 25 GeV electrons. They have measured the LPM effect, where multiple scattering of the radiating electron destroys coherence required for the emission of low-energy photons, and the dielectric effect, where the emitted photon traveling in the radiator medium interferes with itself. For the experiment, the collaboration developed a novel method of extracting a parasitic low-intensity high-energy electron beam into the fixed target area during normal SLC operation of the accelerator. The results agree quantitatively with Migdal`s calculation of the LPM effect. Surface effects, for which there is no satisfactory theoretical prediction, are visible at low photon energies. For very thin targets, the suppression disappears, as expected. Preliminary results on dielectric suppression of bremsstrahlung are in qualitative agreement with the expectation.

  18. Resistance of a rodent malaria parasite to a thymidylate synthase inhibitor induces an apoptotic parasite death and imposes a huge cost of fitness.

    Science.gov (United States)

    Muregi, Francis W; Ohta, Isao; Masato, Uchijima; Kino, Hideto; Ishih, Akira

    2011-01-01

    The greatest impediment to effective malaria control is drug resistance in Plasmodium falciparum, and thus understanding how resistance impacts on the parasite's fitness and pathogenicity may aid in malaria control strategy. To generate resistance, P. berghei NK65 was subjected to 5-fluoroorotate (FOA, an inhibitor of thymidylate synthase, TS) pressure in mice. After 15 generations of drug pressure, the 2% DT (the delay time for proliferation of parasites to 2% parasitaemia, relative to untreated wild-type controls) reduced from 8 days to 4, equalling the controls. Drug sensitivity studies confirmed that FOA-resistance was stable. During serial passaging in the absence of drug, resistant parasite maintained low growth rates (parasitaemia, 15.5%±2.9, 7 dpi) relative to the wild-type (45.6%±8.4), translating into resistance cost of fitness of 66.0%. The resistant parasite showed an apoptosis-like death, as confirmed by light and transmission electron microscopy and corroborated by oligonucleosomal DNA fragmentation. The resistant parasite was less fit than the wild-type, which implies that in the absence of drug pressure in the field, the wild-type alleles may expand and allow drugs withdrawn due to resistance to be reintroduced. FOA resistance led to depleted dTTP pools, causing thymineless parasite death via apoptosis. This supports the tenet that unicellular eukaryotes, like metazoans, also undergo apoptosis. This is the first report where resistance to a chemical stimulus and not the stimulus itself is shown to induce apoptosis in a unicellular parasite. This finding is relevant in cancer therapy, since thymineless cell death induced by resistance to TS-inhibitors can further be optimized via inhibition of pyrimidine salvage enzymes, thus providing a synergistic impact. We conclude that since apoptosis is a process that can be pharmacologically modulated, the parasite's apoptotic machinery may be exploited as a novel drug target in malaria and other protozoan

  19. Evidence that the intra-amoebal Legionella drancourtii acquired a sterol reductase gene from eukaryotes

    Directory of Open Access Journals (Sweden)

    Fournier Pierre-Edouard

    2009-03-01

    Full Text Available Abstract Background Free-living amoebae serve as a natural reservoir for some bacteria that have evolved into «amoeba-resistant» bacteria. Among these, some are strictly intra-amoebal, such as Candidatus "Protochlamydia amoebophila" (Candidatus "P. amoebophila", whose genomic sequence is available. We sequenced the genome of Legionella drancourtii (L. drancourtii, another recently described intra-amoebal bacterium. By comparing these two genomes with those of their closely related species, we were able to study the genetic characteristics specific to their amoebal lifestyle. Findings We identified a sterol delta-7 reductase-encoding gene common to these two bacteria and absent in their relatives. This gene encodes an enzyme which catalyses the last step of cholesterol biosynthesis in eukaryotes, and is probably functional within L. drancourtii since it is transcribed. The phylogenetic analysis of this protein suggests that it was acquired horizontally by a few bacteria from viridiplantae. This gene was also found in the Acanthamoeba polyphaga Mimivirus genome, a virus that grows in amoebae and possesses the largest viral genome known to date. Conclusion L. drancourtii acquired a sterol delta-7 reductase-encoding gene of viridiplantae origin. The most parsimonious hypothesis is that this gene was initially acquired by a Chlamydiales ancestor parasite of plants. Subsequently, its descendents transmitted this gene in amoebae to other intra-amoebal microorganisms, including L. drancourtii and Coxiella burnetii. The role of the sterol delta-7 reductase in prokaryotes is as yet unknown but we speculate that it is involved in host cholesterol parasitism.

  20. Homologous Recombination in Protozoan Parasites and Recombinase Inhibitors

    Directory of Open Access Journals (Sweden)

    Andrew A. Kelso

    2017-09-01

    Full Text Available Homologous recombination (HR is a DNA double-strand break (DSB repair pathway that utilizes a homologous template to fully repair the damaged DNA. HR is critical to maintain genome stability and to ensure genetic diversity during meiosis. A specialized class of enzymes known as recombinases facilitate the exchange of genetic information between sister chromatids or homologous chromosomes with the help of numerous protein accessory factors. The majority of the HR machinery is highly conserved among eukaryotes. In many protozoan parasites, HR is an essential DSB repair pathway that allows these organisms to adapt to environmental conditions and evade host immune systems through genetic recombination. Therefore, small molecule inhibitors, capable of disrupting HR in protozoan parasites, represent potential therapeutic options. A number of small molecule inhibitors were identified that disrupt the activities of the human recombinase RAD51. Recent studies have examined the effect of two of these molecules on the Entamoeba recombinases. Here, we discuss the current understandings of HR in the protozoan parasites Trypanosoma, Leishmania, Plasmodium, and Entamoeba, and we review the small molecule inhibitors known to disrupt human RAD51 activity.

  1. Parasite communities: patterns and processes

    National Research Council Canada - National Science Library

    Esch, Gerald W; Bush, Albert O; Aho, John M

    1990-01-01

    .... Taking examples from many hosts including molluscs, marine and freshwater fish, amphibians, reptiles, birds and mammals, this book shows how parasitic communities are influenced by a multitude...

  2. Eukaryotic checkpoints are absent in the cell division cycle of ...

    Indian Academy of Sciences (India)

    Unknown

    protozoan parasite, Entamoeba histolytica suggest that in its proliferative phase, this organism may accumulate ... phase, despite the failure to undergo complete mitosis ..... CDC2 from Schizosachharomyces pombe; patterns of splicing.

  3. Structure and biochemical characterization of proliferating cellular nuclear antigen from a parasitic protozoon

    Energy Technology Data Exchange (ETDEWEB)

    Cardona-Felix, Cesar S.; Lara-Gonzalez, Samuel; Brieba, Luis G. (LNLS)

    2012-02-08

    Proliferating cellular nuclear antigen (PCNA) is a toroidal-shaped protein that is involved in cell-cycle control, DNA replication and DNA repair. Parasitic protozoa are early-diverged eukaryotes that are responsible for neglected diseases. In this work, a PCNA from a parasitic protozoon was identified, cloned and biochemically characterized and its crystal structure was determined. Structural and biochemical studies demonstrate that PCNA from Entamoeba histolytica assembles as a homotrimer that is able to interact with and stimulate the activity of a PCNA-interacting peptide-motif protein from E. histolytica, EhDNAligI. The data indicate a conservation of the biochemical mechanisms of PCNA-mediated interactions between metazoa, yeast and parasitic protozoa.

  4. Natural suppression of Meloidogyne incognita by Pasteuria penetrans in cotton

    Science.gov (United States)

    The endospore-forming bacterium Pasteuria penetrans is an obligate parasite of root-knot nematodes (Meloidogyne spp.). This bacterium is commonly found in agricultural soils and has been associated with suppression of Meloidogyne spp. In a field site naturally infested with both P. penetrans and M...

  5. Infrared suppression by hybrid EUV multilayer - IR lossy etalon structures

    NARCIS (Netherlands)

    Medvedev, Viacheslav; Yakshin, Andrey; van de Kruijs, Robbert Wilhelmus Elisabeth; Krivtsun, V.M.; Yakunin, A.M.; Bijkerk, Frederik

    2012-01-01

    Many optical applications demand high reflectivity in a particular wavelength range and, simultaneously, suppression of radiation outside this prime range. Such parasitic radiation can lead to image distortions in imaging applications, or poor signal-noise ratios in spectroscopy. When working with

  6. Extreme Ultraviolet Bragg mirrors with suppressed infrared reflectivity properties

    NARCIS (Netherlands)

    Medvedev, Viacheslav; Yakshin, Andrey; Louis, Eric; van de Kruijs, Robbert Wilhelmus Elisabeth; van den Boogaard, Toine; Krivtsun, V.M.; Yakinun, A.M.; Bijkerk, Frederik

    2013-01-01

    Many optical applications demand high reflectivity in a particular wavelength range while simultaneously requiring suppression of radiation outside this range. Such parasitic radiation can for instance lead to image distortions in imaging applications or poor signal-noise ratios in spectroscopy. The

  7. Extreme Ultraviolet Bragg mirrors with suppressed infrared reflectivity properties

    NARCIS (Netherlands)

    Medvedev, Viacheslav; Yakshin, Andrey; Louis, Eric; van de Kruijs, Robbert Wilhelmus Elisabeth; van den Boogaard, Toine; Krivtsun, V.M.; Yakunin, A.M.; Bijkerk, Frederik

    2012-01-01

    Many optical applications demand high reflectivity in a particular wavelength range while simultaneously requiring suppression of radiation outside this range. Such parasitic radiation can for instance lead to image distortions in imaging applications or poor signal-noise ratios in spectroscopy. The

  8. The fitness of drug-resistant malaria parasites in a rodent model: multiplicity of infection

    OpenAIRE

    Huijben, Silvie; Sim, Derek G.; Nelson, William, A.; Read, Andrew F.

    2011-01-01

    Malaria infections normally consist of more than one clonally-replicating lineage. Within-host interactions between sensitive and resistant parasites can have profound effects on the evolution of drug resistance. Here, using the Plasmodium chabaudi mouse malaria model, we ask whether the costs and benefits of resistance are affected by the number of co-infecting strains competing with a resistant clone. We found strong competitive suppression of resistant parasites in untreated infections and...

  9. A novel phytomyxean parasite associated with galls on the bull-kelp Durvillaea antarctica (Chamisso) Hariot.

    Science.gov (United States)

    Goecke, Franz; Wiese, Jutta; Núñez, Alejandra; Labes, Antje; Imhoff, Johannes F; Neuhauser, Sigrid

    2012-01-01

    Durvillaea antarctica (Fucales, Phaeophyceae) is a large kelp of high ecological and economic significance in the Southern Hemisphere. In natural beds along the central coast of Chile (Pacific Ocean), abnormal growth characterized by evident gall development and discolorations of the fronds/thallus was observed. Analysing these galls by light microscopy and scanning electron microscopy revealed the presence of endophytic eukaryotes showing typical characteristics for phytomyxean parasites. The parasite developed within enlarged cells of the subcortical tissue of the host. Multinucleate plasmodia developed into many, single resting spores. The affiliation of this parasite to the Phytomyxea (Rhizaria) was supported by 18S rDNA data, placing it within the Phagomyxida. Similar microorganisms were already reported once 23 years ago, indicating that these parasites are persistent and widespread in D. antarctica beds for long times. The symptoms caused by this parasite are discussed along with the ecological and economic consequences. Phytomyxean parasites may play an important role in the marine ecosystem, but they remain understudied in this environment. Our results demonstrate for the first time the presence of resting spores in Phagomyxida, an order in which resting spores were thought to be absent making this the first record of a phagomyxean parasite with a complete life cycle so far, challenging the existing taxonomic concepts within the Phytomyxea. The importance of the here described resting spores for the survival and ecology of the phagomyxid parasite will be discussed together with the impact this parasite may have on 'the strongest seaweed of the world', which is an important habitat forming and economic resource from the Southern Hemisphere.

  10. A novel phytomyxean parasite associated with galls on the bull-kelp Durvillaea antarctica (Chamisso Hariot.

    Directory of Open Access Journals (Sweden)

    Franz Goecke

    Full Text Available Durvillaea antarctica (Fucales, Phaeophyceae is a large kelp of high ecological and economic significance in the Southern Hemisphere. In natural beds along the central coast of Chile (Pacific Ocean, abnormal growth characterized by evident gall development and discolorations of the fronds/thallus was observed. Analysing these galls by light microscopy and scanning electron microscopy revealed the presence of endophytic eukaryotes showing typical characteristics for phytomyxean parasites. The parasite developed within enlarged cells of the subcortical tissue of the host. Multinucleate plasmodia developed into many, single resting spores. The affiliation of this parasite to the Phytomyxea (Rhizaria was supported by 18S rDNA data, placing it within the Phagomyxida. Similar microorganisms were already reported once 23 years ago, indicating that these parasites are persistent and widespread in D. antarctica beds for long times. The symptoms caused by this parasite are discussed along with the ecological and economic consequences. Phytomyxean parasites may play an important role in the marine ecosystem, but they remain understudied in this environment. Our results demonstrate for the first time the presence of resting spores in Phagomyxida, an order in which resting spores were thought to be absent making this the first record of a phagomyxean parasite with a complete life cycle so far, challenging the existing taxonomic concepts within the Phytomyxea. The importance of the here described resting spores for the survival and ecology of the phagomyxid parasite will be discussed together with the impact this parasite may have on 'the strongest seaweed of the world', which is an important habitat forming and economic resource from the Southern Hemisphere.

  11. Parasitism and calfhood diseases.

    Science.gov (United States)

    Herlich, H; Douvres, F W

    1977-02-01

    That animals can and do acquire an effective immunity against helminth parasites has been demonstrated extensively experimentally, and the fact that domestic animals such as cattle, sheep, and horses become adults while maintaining good health in spite of constant exposure to reinfection long has suggested that immunity must be important to such survival. Although our attempts to date to vaccinate calves against helminth parasites have either failed or been unsatisfactory because of the pathosis induced by the experimental vaccines, the results are not surprising or discouraging. In contrast to the long history of immunization research on bacterial and viral diseases, only within a relatively short time have serious efforts been directed at exploiting hostal immunity for prevention and control of helminthic diseases. Unlike the comparatively simple structures of viruses and bacteria, helminths are complex multicellular animals with vast arrays of antigens and complicated physiological and immunological interactions with their hosts. Much more fundamental information on helminth-bovine interactions, on helminth antigens, and on cattle antibody systems must be developed before progress on control of cattle helminths by vaccination can be meaningful.

  12. Investigation into the Physiological Significance of the Phytohormone Abscisic Acid in Perkinsus marinus, an Oyster Parasite Harboring a Nonphotosynthetic Plastid.

    Science.gov (United States)

    Sakamoto, Hirokazu; Suzuki, Shigeo; Nagamune, Kisaburo; Kita, Kiyoshi; Matsuzaki, Motomichi

    2017-07-01

    Some organisms have retained plastids even after they have lost the ability to photosynthesize. Several studies of nonphotosynthetic plastids in apicomplexan parasites have shown that the isopentenyl pyrophosphate biosynthesis pathway in the organelle is essential for their survival. A phytohormone, abscisic acid, one of several compounds biosynthesized from isopentenyl pyrophosphate, regulates the parasite cell cycle. Thus, it is possible that the phytohormone is universally crucial, even in nonphotosynthetic plastids. Here, we examined this possibility using the oyster parasite Perkinsus marinus, which is a plastid-harboring cousin of apicomplexan parasites and has independently lost photosynthetic ability. Fluridone, an inhibitor of abscisic acid biosynthesis, blocked parasite growth and induced cell clustering. Nevertheless, abscisic acid and its intermediate carotenoids did not affect parasite growth or rescue the parasite from inhibition. Moreover, abscisic acid was not detected from the parasite using liquid chromatography mass spectrometry. Our findings show that abscisic acid does not play any significant roles in P. marinus. © 2016 The Authors. Journal of Eukaryotic Microbiology published by Wiley Periodicals, Inc. on behalf of International Society of Protistologists.

  13. Identification of a Golgi apparatus protein complex important for the asexual erythrocytic cycle of the malaria parasite Plasmodium falciparum.

    Science.gov (United States)

    Hallée, Stéphanie; Thériault, Catherine; Gagnon, Dominic; Kehrer, Jessica; Frischknecht, Friedrich; Mair, Gunnar R; Richard, Dave

    2018-03-26

    Compared with other eukaryotic cell types, malaria parasites appear to possess a more rudimentary Golgi apparatus being composed of dispersed, unstacked cis and trans-cisternae. Despite playing a central role in the secretory pathway of the parasite, few Plasmodium Golgi resident proteins have been characterised. We had previously identified a new Golgi resident protein of unknown function, which we had named Golgi Protein 1, and now show that it forms a complex with a previously uncharacterised transmembrane protein (Golgi Protein 2, GP2). The Golgi Protein complex localises to the cis-Golgi throughout the erythrocytic cycle and potentially also during the mosquito stages. Analysis of parasite strains where GP1 expression is conditionally repressed and/or the GP2 gene is inactivated reveals that though the Golgi protein complex is not essential at any stage of the parasite life cycle, it is important for optimal asexual development in the blood stages. © 2018 John Wiley & Sons Ltd.

  14. Invasion of Eukaryotic Cells by Legionella Pneumophila: A Common Strategy for all Hosts?

    Directory of Open Access Journals (Sweden)

    Paul S Hoffman

    1997-01-01

    Full Text Available Legionella pneumophila is an environmental micro-organism capable of producing an acute lobar pneumonia, commonly referred to as Legionnaires’ disease, in susceptible humans. Legionellae are ubiquitous in aquatic environments, where they survive in biofilms or intracellularly in various protozoans. Susceptible humans become infected by breathing aerosols laden with the bacteria. The target cell for human infection is the alveolar macrophage, in which the bacteria abrogate phagolysosomal fusion. The remarkable ability of L pneumophila to infect a wide range of eukaryotic cells suggests a common strategy that exploits very fundamental cellular processes. The bacteria enter host cells via coiling phagocytosis and quickly subvert organelle trafficking events, leading to formation of a replicative phagosome in which the bacteria multiply. Vegetative growth continues for 8 to 10 h, after which the bacteria develop into a short, highly motile form called the ‘mature form’. The mature form exhibits a thickening of the cell wall, stains red with the Gimenez stain, and is between 10 and 100 times more infectious than agar-grown bacteria. Following host cell lysis, the released bacteria infect other host cells, in which the mature form differentiates into a Gimenez-negative vegetative form, and the cycle begins anew. Virulence of L pneumophila is considered to be multifactorial, and there is growing evidence for both stage specific and sequential gene expression. Thus, L pneumophila may be a good model system for dissecting events associated with the host-parasite interactions.

  15. Winter-summer succession of unicellular eukaryotes in a meso-eutrophic coastal system.

    Science.gov (United States)

    Christaki, Urania; Kormas, Konstantinos A; Genitsaris, Savvas; Georges, Clément; Sime-Ngando, Télesphore; Viscogliosi, Eric; Monchy, Sébastien

    2014-01-01

    The objective of this study was to explore the succession of planktonic unicellular eukaryotes by means of 18S rRNA gene tag pyrosequencing in the eastern English Channel (EEC) during the winter to summer transition. The 59 most representative (>0.1%, representing altogether 95% of total reads), unique operational taxonomic units (OTUs) from all samples belonged to 18 known high-level taxonomic groups and 1 unaffiliated clade. The five most abundant OTUs (69.2% of total reads) belonged to Dinophyceae, Cercozoa, Haptophyceae, marine alveolate group I, and Fungi. Cluster and network analysis between samples distinguished the winter, the pre-bloom, the Phaeocystis globosa bloom and the post-bloom early summer conditions. The OTUs-based network revealed that P. globosa showed a relatively low number of connections-most of them negative-with all other OTUs. Fungi were linked to all major taxonomic groups, except Dinophyceae. Cercozoa mostly co-occurred with the Fungi, the Bacillariophyceae and several of the miscellaneous OTUs. This study provided a more detailed exploration into the planktonic succession pattern of the EEC due to its increased depth of taxonomic sampling over previous efforts based on classical monitoring observations. Data analysis implied that the food web concept in a coastal system based on predator-prey (e.g. grazer-phytoplankton) relationships is just a part of the ecological picture; and those organisms exploiting a variety of strategies, such as saprotrophy and parasitism, are persistent and abundant members of the community.

  16. Subversion of Immunity by Leishmania amazonensis Parasites: Possible Role of Phosphatidylserine as a Main Regulator

    Directory of Open Access Journals (Sweden)

    Joao Luiz Mendes Wanderley

    2012-01-01

    Full Text Available Leishmania amazonensis parasites cause progressive disease in most inbred mouse strains and are associated with the development of diffuse cutaneous leishmaniasis in humans. The poor activation of an effective cellular response is correlated with the ability of these parasites to infect mononuclear phagocytic cells without triggering their activation or actively suppressing innate responses of these cells. Here we discuss the possible role of phosphatidylserine exposure by these parasites as a main regulator of the mechanism underlying subversion of the immune system at different steps during the infection.

  17. Repetitive elements in parasitic protozoa

    Directory of Open Access Journals (Sweden)

    Clayton Christine

    2010-05-01

    Full Text Available Abstract A recent paper published in BMC Genomics suggests that retrotransposition may be active in the human gut parasite Entamoeba histolytica. This adds to our knowledge of the various types of repetitive elements in parasitic protists and the potential influence of such elements on pathogenicity. See research article http://www.biomedcentral.com/1471-2164/11/321

  18. Remarkable interkingdom conservation of intron positions and massive, lineage-specific intron loss and gain in eukaryotic evolution.

    Science.gov (United States)

    Rogozin, Igor B; Wolf, Yuri I; Sorokin, Alexander V; Mirkin, Boris G; Koonin, Eugene V

    2003-09-02

    Sequencing of eukaryotic genomes allows one to address major evolutionary problems, such as the evolution of gene structure. We compared the intron positions in 684 orthologous gene sets from 8 complete genomes of animals, plants, fungi, and protists and constructed parsimonious scenarios of evolution of the exon-intron structure for the respective genes. Approximately one-third of the introns in the malaria parasite Plasmodium falciparum are shared with at least one crown group eukaryote; this number indicates that these introns have been conserved through >1.5 billion years of evolution that separate Plasmodium from the crown group. Paradoxically, humans share many more introns with the plant Arabidopsis thaliana than with the fly or nematode. The inferred evolutionary scenario holds that the common ancestor of Plasmodium and the crown group and, especially, the common ancestor of animals, plants, and fungi had numerous introns. Most of these ancestral introns, which are retained in the genomes of vertebrates and plants, have been lost in fungi, nematodes, arthropods, and probably Plasmodium. In addition, numerous introns have been inserted into vertebrate and plant genes, whereas, in other lineages, intron gain was much less prominent.

  19. Re-evaluating the green versus red signal in eukaryotes with secondary plastid of red algal origin

    KAUST Repository

    Burki, Fabien

    2012-05-16

    The transition from endosymbiont to organelle in eukaryotic cells involves the transfer of significant numbers of genes to the host genomes, a process known as endosymbiotic gene transfer (EGT). In the case of plastid organelles, EGTs have been shown to leave a footprint in the nuclear genome that can be indicative of ancient photosynthetic activity in present-day plastid-lacking organisms, or even hint at the existence of cryptic plastids. Here,we evaluated the impact of EGTon eukaryote genomes by reanalyzing the recently published EST dataset for Chromera velia, an interesting test case of a photosynthetic alga closely related to apicomplexan parasites. Previously, 513 genes were reported to originate from red and green algae in a 1:1 ratio. In contrast, by manually inspecting newly generated trees indicating putative algal ancestry, we recovered only 51 genes congruent with EGT, of which 23 and 9 were of red and green algal origin, respectively,whereas 19 were ambiguous regarding the algal provenance.Our approach also uncovered 109 genes that branched within a monocot angiosperm clade, most likely representing a contamination. We emphasize the lack of congruence and the subjectivity resulting from independent phylogenomic screens for EGT, which appear to call for extreme caution when drawing conclusions for major evolutionary events. 2012 The Author(s).

  20. Exploring the host parasitism of the migratory plant-parasitic nematode Ditylenchus destuctor by expressed sequence tags analysis.

    Directory of Open Access Journals (Sweden)

    Huan Peng

    Full Text Available The potato rot nematode, Ditylenchus destructor, is a very destructive nematode pest on many agriculturally important crops worldwide, but the molecular characterization of its parasitism of plant has been limited. The effectors involved in nematode parasitism of plant for several sedentary endo-parasitic nematodes such as Heterodera glycines, Globodera rostochiensis and Meloidogyne incognita have been identified and extensively studied over the past two decades. Ditylenchus destructor, as a migratory plant parasitic nematode, has different feeding behavior, life cycle and host response. Comparing the transcriptome and parasitome among different types of plant-parasitic nematodes is the way to understand more fully the parasitic mechanism of plant nematodes. We undertook the approach of sequencing expressed sequence tags (ESTs derived from a mixed stage cDNA library of D. destructor. This is the first study of D. destructor ESTs. A total of 9800 ESTs were grouped into 5008 clusters including 3606 singletons and 1402 multi-member contigs, representing a catalog of D. destructor genes. Implementing a bioinformatics' workflow, we found 1391 clusters have no match in the available gene database; 31 clusters only have similarities to genes identified from D. africanus, the most closely related species to D. destructor; 1991 clusters were annotated using Gene Ontology (GO; 1550 clusters were assigned enzyme commission (EC numbers; and 1211 clusters were mapped to 181 KEGG biochemical pathways. 22 ESTs had similarities to reported nematode effectors. Interestedly, most of the effectors identified in this study are involved in host cell wall degradation or modification, such as 1,4-beta-glucanse, 1,3-beta-glucanse, pectate lyase, chitinases and expansin, or host defense suppression such as calreticulin, annexin and venom allergen-like protein. This result implies that the migratory plant-parasitic nematode D. destructor secrets similar effectors to

  1. Anionic lipids and the maintenance of membrane electrostatics in eukaryotes.

    Science.gov (United States)

    Platre, Matthieu Pierre; Jaillais, Yvon

    2017-02-01

    A wide range of signaling processes occurs at the cell surface through the reversible association of proteins from the cytosol to the plasma membrane. Some low abundant lipids are enriched at the membrane of specific compartments and thereby contribute to the identity of cell organelles by acting as biochemical landmarks. Lipids also influence membrane biophysical properties, which emerge as an important feature in specifying cellular territories. Such parameters are crucial for signal transduction and include lipid packing, membrane curvature and electrostatics. In particular, membrane electrostatics specifies the identity of the plasma membrane inner leaflet. Membrane surface charges are carried by anionic phospholipids, however the exact nature of the lipid(s) that powers the plasma membrane electrostatic field varies among eukaryotes and has been hotly debated during the last decade. Herein, we discuss the role of anionic lipids in setting up plasma membrane electrostatics and we compare similarities and differences that were found in different eukaryotic cells.

  2. Regulated eukaryotic DNA replication origin firing with purified proteins.

    Science.gov (United States)

    Yeeles, Joseph T P; Deegan, Tom D; Janska, Agnieszka; Early, Anne; Diffley, John F X

    2015-03-26

    Eukaryotic cells initiate DNA replication from multiple origins, which must be tightly regulated to promote precise genome duplication in every cell cycle. To accomplish this, initiation is partitioned into two temporally discrete steps: a double hexameric minichromosome maintenance (MCM) complex is first loaded at replication origins during G1 phase, and then converted to the active CMG (Cdc45-MCM-GINS) helicase during S phase. Here we describe the reconstitution of budding yeast DNA replication initiation with 16 purified replication factors, made from 42 polypeptides. Origin-dependent initiation recapitulates regulation seen in vivo. Cyclin-dependent kinase (CDK) inhibits MCM loading by phosphorylating the origin recognition complex (ORC) and promotes CMG formation by phosphorylating Sld2 and Sld3. Dbf4-dependent kinase (DDK) promotes replication by phosphorylating MCM, and can act either before or after CDK. These experiments define the minimum complement of proteins, protein kinase substrates and co-factors required for regulated eukaryotic DNA replication.

  3. Temporal and demographic blood parasite dynamics in two free-ranging neotropical primates

    Directory of Open Access Journals (Sweden)

    Gideon A. Erkenswick

    2017-08-01

    Full Text Available Parasite-host relationships are influenced by several factors intrinsic to hosts, such as social standing, group membership, sex, and age. However, in wild populations, temporal variation in parasite distributions and concomitant infections can alter these patterns. We used microscropy and molecular methods to screen for naturally occurring haemoparasitic infections in two Neotropical primate host populations, the saddleback (Leontocebus weddelli and emperor (Saguinus imperator tamarin, in the lowland tropical rainforests of southeastern Peru. Repeat sampling was conducted from known individuals over a three-year period to test for parasite-host and parasite-parasite associations. Three parasites were detected in L. weddelli including Trypanosoma minasense, Mansonella mariae, and Dipetalonema spp., while S. imperator only hosted the latter two. Temporal variation in prevalence was observed in T. minasense and Dipetalonema spp., confirming the necessity of a multi-year study to evaluate parasite-host relationships in this system. Although callitrichids display a distinct reproductive dominance hierarchy, characterized by single breeding females that typically mate polyandrously and can suppress the reproduction of subdominant females, logistic models did not identify sex or breeding status as determining factors in the presence of these parasites. However, age class had a positive effect on infection with M. mariae and T. minasense, and adults demonstrated higher parasite species richness than juveniles or sub-adults across both species. Body weight had a positive effect on the presence of Dipetalonema spp. The inclusion of co-infection variables in statistical models of parasite presence/absence data improved model fit for two of three parasites. This study verifies the importance and need for broad spectrum and long-term screening of parasite assemblages of natural host populations.

  4. Reciprocal relationships between behaviour and parasites suggest that negative feedback may drive flexibility in male reproductive behaviour.

    Science.gov (United States)

    Ezenwa, Vanessa O; Snider, Matthew H

    2016-05-25

    Parasites are ubiquitous components of the environment that contribute to behavioural and life-history variation among hosts. Although it is well known that host behaviour can affect parasite infection risk and that parasites can alter host behaviour, the potential for dynamic feedback between these processes is poorly characterized. Using Grant's gazelle (Nanger granti) as a model, we tested for reciprocal effects of behaviour on parasites and parasites on behaviour to understand whether behaviour-parasite feedback could play a role in maintaining variation in male reproductive behaviour. Adult male gazelles either defend territories to attract mates or reside in bachelor groups. Territoriality is highly variable both within- and between-individuals, suggesting that territory maintenance is costly. Using a combination of longitudinal and experimental studies, we found that individual males transition frequently between territorial and bachelor reproductive status, and that elevated parasite burdens are a cost of territoriality. Moreover, among territorial males, parasites suppress aspects of behaviour related to territory maintenance and defence. These results suggest that territorial behaviour promotes the accumulation of parasites in males, and these parasites dampen the very behaviours required for territory maintenance. Our findings suggest that reciprocal feedback between host behaviour and parasitism could be a mechanism maintaining variation in male reproductive behaviour in the system. © 2016 The Author(s).

  5. Integrated parasite management

    DEFF Research Database (Denmark)

    Clausen, Jesper Hedegaard; Madsen, Henry; Van, Phan Thi

    2015-01-01

    communities at risk through mass drug administration. However, we argue that treatment alone will not reduce the risk from eating infected fish and that sustainable effective control must adopt an integrated FZT control approach based on education, infrastructure improvements, and management practices...... that target critical control points in the aquaculture production cycle identified from a thorough understanding of FZT and host biology and epidemiology. We present recommendations for an integrated parasite management (IPM) program for aquaculture farms.......Fishborne zoonotic trematodes (FZT) are an emerging problem and there is now a consensus that, in addition to wild-caught fish, fish produced in aquaculture present a major food safety risk, especially in Southeast Asia where aquaculture is important economically. Current control programs target...

  6. The MCM Helicase Motor of the Eukaryotic Replisome.

    Science.gov (United States)

    Abid Ali, Ferdos; Costa, Alessandro

    2016-05-08

    The MCM motor of the CMG helicase powers ahead of the eukaryotic replication machinery to unwind DNA, in a process that requires ATP hydrolysis. The reconstitution of DNA replication in vitro has established the succession of events that lead to replication origin activation by the MCM and recent studies have started to elucidate the structural basis of duplex DNA unwinding. Despite the exciting progress, how the MCM translocates on DNA remains a matter of debate. Copyright © 2016. Published by Elsevier Ltd.

  7. Biological Influence of Deuterium on Procariotic and Eukaryotic Cells

    OpenAIRE

    Oleg Mosin; Ignat Ignatov

    2014-01-01

    Biologic influence of deuterium (D) on cells of various taxonomic groups of prokaryotic and eukaryotic microorganisms realizing methylotrophic, chemoheterotrophic, photo-organotrophic, and photosynthetic ways of assimilation of carbon substrates are investigated at growth on media with heavy water (D2О). The method of step by step adaptation technique of cells to D2О was developed, consisting in plating of cells on 2 % agarose nutrient media containing increasing gradient of concentration of ...

  8. An Evolutionary Framework for Understanding the Origin of Eukaryotes

    OpenAIRE

    Neil W. Blackstone

    2016-01-01

    Two major obstacles hinder the application of evolutionary theory to the origin of eukaryotes. The first is more apparent than real?the endosymbiosis that led to the mitochondrion is often described as ?non-Darwinian? because it deviates from the incremental evolution championed by the modern synthesis. Nevertheless, endosymbiosis can be accommodated by a multi-level generalization of evolutionary theory, which Darwin himself pioneered. The second obstacle is more serious?all of the major fea...

  9. Gram-Negative Bacterial Sensors for Eukaryotic Signal Molecules

    Directory of Open Access Journals (Sweden)

    Olivier Lesouhaitier

    2009-09-01

    Full Text Available Ample evidence exists showing that eukaryotic signal molecules synthesized and released by the host can activate the virulence of opportunistic pathogens. The sensitivity of prokaryotes to host signal molecules requires the presence of bacterial sensors. These prokaryotic sensors, or receptors, have a double function: stereospecific recognition in a complex environment and transduction of the message in order to initiate bacterial physiological modifications. As messengers are generally unable to freely cross the bacterial membrane, they require either the presence of sensors anchored in the membrane or transporters allowing direct recognition inside the bacterial cytoplasm. Since the discovery of quorum sensing, it was established that the production of virulence factors by bacteria is tightly growth-phase regulated. It is now obvious that expression of bacterial virulence is also controlled by detection of the eukaryotic messengers released in the micro-environment as endocrine or neuro-endocrine modulators. In the presence of host physiological stress many eukaryotic factors are released and detected by Gram-negative bacteria which in return rapidly adapt their physiology. For instance, Pseudomonas aeruginosa can bind elements of the host immune system such as interferon-γ and dynorphin and then through quorum sensing circuitry enhance its virulence. Escherichia coli sensitivity to the neurohormones of the catecholamines family appears relayed by a recently identified bacterial adrenergic receptor. In the present review, we will describe the mechanisms by which various eukaryotic signal molecules produced by host may activate Gram-negative bacteria virulence. Particular attention will be paid to Pseudomonas, a genus whose representative species, P. aeruginosa, is a common opportunistic pathogen. The discussion will be particularly focused on the pivotal role played by these new types of pathogen sensors from the sensing to the transduction

  10. Replication and Transcription of Eukaryotic DNA in Esherichia coli

    Science.gov (United States)

    Morrow, John F.; Cohen, Stanley N.; Chang, Annie C. Y.; Boyer, Herbert W.; Goodman, Howard M.; Helling, Robert B.

    1974-01-01

    Fragments of amplified Xenopus laevis DNA, coding for 18S and 28S ribosomal RNA and generated by EcoRI restriction endonuclease, have been linked in vitro to the bacterial plasmid pSC101; and the recombinant molecular species have been introduced into E. coli by transformation. These recombinant plasmids, containing both eukaryotic and prokaryotic DNA, replicate stably in E. coli. RNA isolated from E. coli minicells harboring the plasmids hybridizes to amplified X. laevis rDNA. Images PMID:4600264

  11. Extreme Diversity of Diplonemid Eukaryotes in the Ocean

    Czech Academy of Sciences Publication Activity Database

    Flegontova, Olga; Flegontov, Pavel; Malviya, S.; Audic, S.; Wincker, P.; de Vargas, C.; Bowler, C.; Lukeš, Julius; Horák, Aleš

    2016-01-01

    Roč. 26, č. 22 (2016), s. 3060-3065 ISSN 0960-9822 R&D Projects: GA ČR GPP506/12/P931; GA ČR(CZ) GA14-23986S Institutional support: RVO:60077344 Keywords : virus-sized particles * microbial eukaryotes * sea-floor * phytoplankton * communities * euglenozoa * dispersal * ecosystem Subject RIV: EG - Zoology Impact factor: 8.851, year: 2016

  12. diArk – a resource for eukaryotic genome research

    Directory of Open Access Journals (Sweden)

    Kollmar Martin

    2007-04-01

    Full Text Available Abstract Background The number of completed eukaryotic genome sequences and cDNA projects has increased exponentially in the past few years although most of them have not been published yet. In addition, many microarray analyses yielded thousands of sequenced EST and cDNA clones. For the researcher interested in single gene analyses (from a phylogenetic, a structural biology or other perspective it is therefore important to have up-to-date knowledge about the various resources providing primary data. Description The database is built around 3 central tables: species, sequencing projects and publications. The species table contains commonly and alternatively used scientific names, common names and the complete taxonomic information. For projects the sequence type and links to species project web-sites and species homepages are stored. All publications are linked to projects. The web-interface provides comprehensive search modules with detailed options and three different views of the selected data. We have especially focused on developing an elaborate taxonomic tree search tool that allows the user to instantaneously identify e.g. the closest relative to the organism of interest. Conclusion We have developed a database, called diArk, to store, organize, and present the most relevant information about completed genome projects and EST/cDNA data from eukaryotes. Currently, diArk provides information about 415 eukaryotes, 823 sequencing projects, and 248 publications.

  13. Biotransformation of arsenic by a Yellowstone thermoacidophilic eukaryotic alga.

    Science.gov (United States)

    Qin, Jie; Lehr, Corinne R; Yuan, Chungang; Le, X Chris; McDermott, Timothy R; Rosen, Barry P

    2009-03-31

    Arsenic is the most common toxic substance in the environment, ranking first on the Superfund list of hazardous substances. It is introduced primarily from geochemical sources and is acted on biologically, creating an arsenic biogeocycle. Geothermal environments are known for their elevated arsenic content and thus provide an excellent setting in which to study microbial redox transformations of arsenic. To date, most studies of microbial communities in geothermal environments have focused on Bacteria and Archaea, with little attention to eukaryotic microorganisms. Here, we show the potential of an extremophilic eukaryotic alga of the order Cyanidiales to influence arsenic cycling at elevated temperatures. Cyanidioschyzon sp. isolate 5508 oxidized arsenite [As(III)] to arsenate [As(V)], reduced As(V) to As(III), and methylated As(III) to form trimethylarsine oxide (TMAO) and dimethylarsenate [DMAs(V)]. Two arsenic methyltransferase genes, CmarsM7 and CmarsM8, were cloned from this organism and demonstrated to confer resistance to As(III) in an arsenite hypersensitive strain of Escherichia coli. The 2 recombinant CmArsMs were purified and shown to transform As(III) into monomethylarsenite, DMAs(V), TMAO, and trimethylarsine gas, with a T(opt) of 60-70 degrees C. These studies illustrate the importance of eukaryotic microorganisms to the biogeochemical cycling of arsenic in geothermal systems, offer a molecular explanation for how these algae tolerate arsenic in their environment, and provide the characterization of algal methyltransferases.

  14. Ubiquitination dynamics in the early-branching eukaryote Giardia intestinalis

    Science.gov (United States)

    Niño, Carlos A; Chaparro, Jenny; Soffientini, Paolo; Polo, Simona; Wasserman, Moises

    2013-01-01

    Ubiquitination is a highly dynamic and versatile posttranslational modification that regulates protein function, stability, and interactions. To investigate the roles of ubiquitination in a primitive eukaryotic lineage, we utilized the early-branching eukaryote Giardia intestinalis. Using a combination of biochemical, immunofluorescence-based, and proteomics approaches, we assessed the ubiquitination status during the process of differentiation in Giardia. We observed that different types of ubiquitin modifications present specific cellular and temporal distribution throughout the Giardia life cycle from trophozoites to cyst maturation. Ubiquitin signal was detected in the wall of mature cysts, and enzymes implicated in cyst wall biogenesis were identified as substrates for ubiquitination. Interestingly, inhibition of proteasome activity did not affect trophozoite replication and differentiation, while it caused a decrease in cyst viability, arguing for proteasome involvement in cyst wall maturation. Using a proteomics approach, we identified around 200 high-confidence ubiquitinated candidates that vary their ubiquitination status during differentiation. Our results indicate that ubiquitination is critical for several cellular processes in this primitive eukaryote. PMID:23613346

  15. Gene Transfer in Eukaryotic Cells Using Activated Dendrimers

    Science.gov (United States)

    Dennig, Jörg

    Gene transfer into eukaryotic cells plays an important role in cell biology. Over the last 30 years a number of transfection methods have been developed to mediate gene transfer into eukaryotic cells. Classical methods include co-precipitation of DNA with calcium phosphate, charge-dependent precipitation of DNA with DEAE-dextran, electroporation of nucleic acids, and formation of transfection complexes between DNA and cationic liposomes. Gene transfer technologies based on activated PAMAM-dendrimers provide another class of transfection reagents. PAMAM-dendrimers are highly branched, spherical molecules. Activation of newly synthesized dendrimers involves hydrolytic removal of some of the branches, and results in a molecule with a higher degree of flexibility. Activated dendrimers assemble DNA into compact structures via charge interactions. Activated dendrimer - DNA complexes bind to the cell membrane of eukaryotic cells, and are transported into the cell by non-specific endocytosis. A structural model of the activated dendrimer - DNA complex and a potential mechanism for its uptake into cells will be discussed.

  16. Enzymes involved in organellar DNA replication in photosynthetic eukaryotes.

    Science.gov (United States)

    Moriyama, Takashi; Sato, Naoki

    2014-01-01

    Plastids and mitochondria possess their own genomes. Although the replication mechanisms of these organellar genomes remain unclear in photosynthetic eukaryotes, several organelle-localized enzymes related to genome replication, including DNA polymerase, DNA primase, DNA helicase, DNA topoisomerase, single-stranded DNA maintenance protein, DNA ligase, primer removal enzyme, and several DNA recombination-related enzymes, have been identified. In the reference Eudicot plant Arabidopsis thaliana, the replication-related enzymes of plastids and mitochondria are similar because many of them are dual targeted to both organelles, whereas in the red alga Cyanidioschyzon merolae, plastids and mitochondria contain different replication machinery components. The enzymes involved in organellar genome replication in green plants and red algae were derived from different origins, including proteobacterial, cyanobacterial, and eukaryotic lineages. In the present review, we summarize the available data for enzymes related to organellar genome replication in green plants and red algae. In addition, based on the type and distribution of replication enzymes in photosynthetic eukaryotes, we discuss the transitional history of replication enzymes in the organelles of plants.

  17. Mechanisms and regulation of DNA replication initiation in eukaryotes.

    Science.gov (United States)

    Parker, Matthew W; Botchan, Michael R; Berger, James M

    2017-04-01

    Cellular DNA replication is initiated through the action of multiprotein complexes that recognize replication start sites in the chromosome (termed origins) and facilitate duplex DNA melting within these regions. In a typical cell cycle, initiation occurs only once per origin and each round of replication is tightly coupled to cell division. To avoid aberrant origin firing and re-replication, eukaryotes tightly regulate two events in the initiation process: loading of the replicative helicase, MCM2-7, onto chromatin by the origin recognition complex (ORC), and subsequent activation of the helicase by its incorporation into a complex known as the CMG. Recent work has begun to reveal the details of an orchestrated and sequential exchange of initiation factors on DNA that give rise to a replication-competent complex, the replisome. Here, we review the molecular mechanisms that underpin eukaryotic DNA replication initiation - from selecting replication start sites to replicative helicase loading and activation - and describe how these events are often distinctly regulated across different eukaryotic model organisms.

  18. Evolution of the protists and protistan parasites from the perspective of molecular systematics.

    Science.gov (United States)

    Sogin, M L; Silberman, J D

    1998-01-01

    phylogenetic affinity of many parasitic groups as well as a means to integrate molecular and cell biological information from diverse eukaryotes. We must place greater emphasis upon improved phylogenetic inference techniques and investigations of genomic diversity in protists.

  19. How have fisheries affected parasite communities?

    Science.gov (United States)

    Wood, Chelsea L; Lafferty, Kevin D

    2015-01-01

    To understand how fisheries affect parasites, we conducted a meta-analysis of studies that contrasted parasite assemblages in fished and unfished areas. Parasite diversity was lower in hosts from fished areas. Larger hosts had a greater abundance of parasites, suggesting that fishing might reduce the abundance of parasites by selectively removing the largest, most heavily parasitized individuals. After controlling for size, the effect of fishing on parasite abundance varied according to whether the host was fished and the parasite's life cycle. Parasites of unfished hosts were more likely to increase in abundance in response to fishing than were parasites of fished hosts, possibly due to compensatory increases in the abundance of unfished hosts. While complex life cycle parasites tended to decline in abundance in response to fishing, directly transmitted parasites tended to increase. Among complex life cycle parasites, those with fished hosts tended to decline in abundance in response to fishing, while those with unfished hosts tended to increase. However, among directly transmitted parasites, responses did not differ between parasites with and without fished hosts. This work suggests that parasite assemblages are likely to change substantially in composition in increasingly fished ecosystems, and that parasite life history and fishing status of the host are important in predicting the response of individual parasite species or groups to fishing.

  20. Dexamethasone suppression test

    Science.gov (United States)

    DST; ACTH suppression test; Cortisol suppression test ... During this test, you will receive dexamethasone. This is a strong man-made (synthetic) glucocorticoid medicine. Afterward, your blood is drawn ...

  1. Origin of phagotrophic eukaryotes as social cheaters in microbial biofilms

    Directory of Open Access Journals (Sweden)

    Jékely Gáspár

    2007-01-01

    Full Text Available Abstract Background The origin of eukaryotic cells was one of the most dramatic evolutionary transitions in the history of life. It is generally assumed that eukaryotes evolved later then prokaryotes by the transformation or fusion of prokaryotic lineages. However, as yet there is no consensus regarding the nature of the prokaryotic group(s ancestral to eukaryotes. Regardless of this, a hardly debatable fundamental novel characteristic of the last eukaryotic common ancestor was the ability to exploit prokaryotic biomass by the ingestion of entire cells, i.e. phagocytosis. The recent advances in our understanding of the social life of prokaryotes may help to explain the origin of this form of total exploitation. Presentation of the hypothesis Here I propose that eukaryotic cells originated in a social environment, a differentiated microbial mat or biofilm that was maintained by the cooperative action of its members. Cooperation was costly (e.g. the production of developmental signals or an extracellular matrix but yielded benefits that increased the overall fitness of the social group. I propose that eukaryotes originated as selfish cheaters that enjoyed the benefits of social aggregation but did not contribute to it themselves. The cheaters later evolved into predators that lysed other cells and eventually became professional phagotrophs. During several cycles of social aggregation and dispersal the number of cheaters was contained by a chicken game situation, i.e. reproductive success of cheaters was high when they were in low abundance but was reduced when they were over-represented. Radical changes in cell structure, including the loss of the rigid prokaryotic cell wall and the development of endomembranes, allowed the protoeukaryotes to avoid cheater control and to exploit nutrients more efficiently. Cellular changes were buffered by both the social benefits and the protective physico-chemical milieu of the interior of biofilms. Symbiosis

  2. Stripped-down DNA repair in a highly reduced parasite

    Directory of Open Access Journals (Sweden)

    Fast Naomi M

    2007-03-01

    Full Text Available Abstract Background Encephalitozoon cuniculi is a member of a distinctive group of single-celled parasitic eukaryotes called microsporidia, which are closely related to fungi. Some of these organisms, including E. cuniculi, also have uniquely small genomes that are within the prokaryotic range. Thus, E. cuniculi has undergone a massive genome reduction which has resulted in a loss of genes from diverse biological pathways, including those that act in DNA repair. DNA repair is essential to any living cell. A loss of these mechanisms invariably results in accumulation of mutations and/or cell death. Six major pathways of DNA repair in eukaryotes include: non-homologous end joining (NHEJ, homologous recombination repair (HRR, mismatch repair (MMR, nucleotide excision repair (NER, base excision repair (BER and methyltransferase repair. DNA polymerases are also critical players in DNA repair processes. Given the close relationship between microsporidia and fungi, the repair mechanisms present in E. cuniculi were compared to those of the yeast Saccharomyces cerevisiae to ascertain how the process of genome reduction has affected the DNA repair pathways. Results E. cuniculi lacks 16 (plus another 6 potential absences of the 56 DNA repair genes sought via BLASTP and PSI-BLAST searches. Six of 14 DNA polymerases or polymerase subunits are also absent in E. cuniculi. All of these genes are relatively well conserved within eukaryotes. The absence of genes is not distributed equally among the different repair pathways; some pathways lack only one protein, while there is a striking absence of many proteins that are components of both double strand break repair pathways. All specialized repair polymerases are also absent. Conclusion Given the large number of DNA repair genes that are absent from the double strand break repair pathways, E. cuniculi is a prime candidate for the study of double strand break repair with minimal machinery. Strikingly, all of the

  3. Deconstructing continuous flash suppression

    OpenAIRE

    Yang, Eunice; Blake, Randolph

    2012-01-01

    In this paper, we asked to what extent the depth of interocular suppression engendered by continuous flash suppression (CFS) varies depending on spatiotemporal properties of the suppressed stimulus and CFS suppressor. An answer to this question could have implications for interpreting the results in which CFS influences the processing of different categories of stimuli to different extents. In a series of experiments, we measured the selectivity and depth of suppression (i.e., elevation in co...

  4. Origin and evolution of the self-organizing cytoskeleton in the network of eukaryotic organelles.

    Science.gov (United States)

    Jékely, Gáspár

    2014-09-02

    The eukaryotic cytoskeleton evolved from prokaryotic cytomotive filaments. Prokaryotic filament systems show bewildering structural and dynamic complexity and, in many aspects, prefigure the self-organizing properties of the eukaryotic cytoskeleton. Here, the dynamic properties of the prokaryotic and eukaryotic cytoskeleton are compared, and how these relate to function and evolution of organellar networks is discussed. The evolution of new aspects of filament dynamics in eukaryotes, including severing and branching, and the advent of molecular motors converted the eukaryotic cytoskeleton into a self-organizing "active gel," the dynamics of which can only be described with computational models. Advances in modeling and comparative genomics hold promise of a better understanding of the evolution of the self-organizing cytoskeleton in early eukaryotes, and its role in the evolution of novel eukaryotic functions, such as amoeboid motility, mitosis, and ciliary swimming. Copyright © 2014 Cold Spring Harbor Laboratory Press; all rights reserved.

  5. Parasites in pet reptiles

    Directory of Open Access Journals (Sweden)

    Mavri Urška

    2011-05-01

    Full Text Available Abstract Exotic reptiles originating from the wild can be carriers of many different pathogens and some of them can infect humans. Reptiles imported into Slovenia from 2000 to 2005, specimens of native species taken from the wild and captive bred species were investigated. A total of 949 reptiles (55 snakes, 331 lizards and 563 turtles, belonging to 68 different species, were examined for the presence of endoparasites and ectoparasites. Twelve different groups (Nematoda (5, Trematoda (1, Acanthocephala (1, Pentastomida (1 and Protozoa (4 of endoparasites were determined in 26 (47.3% of 55 examined snakes. In snakes two different species of ectoparasites were also found. Among the tested lizards eighteen different groups (Nematoda (8, Cestoda (1, Trematoda (1, Acanthocephala (1, Pentastomida (1 and Protozoa (6 of endoparasites in 252 (76.1% of 331 examined animals were found. One Trombiculid ectoparasite was determined. In 563 of examined turtles eight different groups (Nematoda (4, Cestoda (1, Trematoda (1 and Protozoa (2 of endoparasites were determined in 498 (88.5% animals. In examined turtles three different species of ectoparasites were seen. The established prevalence of various parasites in reptiles used as pet animals indicates the need for examination on specific pathogens prior to introduction to owners.

  6. Diversity and distribution of eukaryotic microbes in and around a brine pool adjacent to the Thuwal cold seeps in the Red Sea

    KAUST Repository

    Wang, Yong

    2014-02-04

    A hypoxic/suboxic brine pool at a depth of about 850 m was discovered near the Thuwal cold seeps in the Red Sea. Filled with high concentrations of hydrogen sulfide and ammonia, such a brine pool might limit the spread of eukaryotic organisms. Here, we compared the communities of the eukaryotic microbes in a microbial mat, sediments and water samples distributed in 7 sites within and adjacent to the brine pool. Taxonomic classification of the pyrosequenced 18S rRNA amplicon reads showed that fungi highly similar to the species identified along the Arabic coast were almost ubiquitous in the water and sediment samples, supporting their wide distribution in various environments. The microbial mat displayed the highest species diversity and contained grazers and a considerable percentage of unclassified species. Phylogeny-based methods revealed novel lineages representing a majority of the reads from the interface between the sea water and brine pool. Phylogenetic relationships with more reference sequences suggest that the lineages were affiliated with novel Alveolata and Euglenozoa inhabiting the interface where chemosynthetic prokaryotes are highly proliferative due to the strong chemocline and halocline. The brine sediments harbored abundant species highly similar to invertebrate gregarine parasites identified in different oxygen-depleted sediments. Therefore, the present findings support the uniqueness of some microbial eukaryotic groups in this cold seep brine system. 2014 Wang, Zhang, Cao, Shek, Tian, Wong, Batang, Al-suwailem and Qian.

  7. Cloning and expression of an iron-containing superoxide dismutase in the parasitic protist, Trichomonas vaginalis.

    Science.gov (United States)

    Viscogliosi, E; Delgado-Viscogliosi, P; Gerbod, D; Dauchez, M; Gratepanche, S; Alix, A J; Dive, D

    1998-04-01

    A superoxide dismutase (SOD) gene of the parasitic protist Trichomonas vaginalis was cloned, sequenced, expressed in Escherichia coli, and its gene product characterized. It is an iron-containing dimeric protein with a monomeric mass of 22,067 Da. Southern blots analyses suggested the presence of seven iron-containing (FeSOD) gene copies. Hydrophobic cluster analysis revealed some peculiarities in the 2D structure of the FeSOD from T. vaginalis and a strong structural conservation between prokaryotic and eukaryotic FeSODs. Phylogenetic reconstruction of the SOD sequences confirmed the dichotomy between FeSODs and manganese-containing SODs. FeSODs of protists appeared to group together with homologous proteobacterial enzymes suggesting a possible origin of eukaryotic FeSODs through an endosymbiotic event.

  8. Fauna Europaea: Helminths (Animal Parasitic)

    Czech Academy of Sciences Publication Activity Database

    Gibson, D. I.; Bray, R. A.; Hunt, D.; Georgiev, B. B.; Scholz, Tomáš; Harris, P.D.; Bakke, T.A.; Pomajska, T.; Niewiadomska, K.; Kostadinova, Aneta; Tkach, V.; Bain, O.; Durette-Desset, M.-C.; Gibbons, L.; Moravec, František; Petter, A.; Dimitrova, Z.M.; Buchmann, K.; Valtonen, E. T.; de Jong, Y.

    -, č. 2 (2014), e1060 ISSN 1314-2828 Institutional support: RVO:60077344 Keywords : Acanthocephala * Biodiversity * Biodiversity Informatics * Cestoda * Fauna Europaea * Helminth * Monogenea * Nematoda * Parasite * Taxonomic indexing * Taxonomy * Trematoda * Zoology Subject RIV: EB - Genetics ; Molecular Biology

  9. Chromerid genomes reveal the evolutionary path from photosynthetic algae to obligate intracellular parasites

    KAUST Repository

    Woo, Yong

    2015-07-15

    The eukaryotic phylum Apicomplexa encompasses thousands of obligate intracellular parasites of humans and animals with immense socio-economic and health impacts. We sequenced nuclear genomes of Chromera velia and Vitrella brassicaformis, free-living non-parasitic photosynthetic algae closely related to apicomplexans. Proteins from key metabolic pathways and from the endomembrane trafficking systems associated with a free-living lifestyle have been progressively and non-randomly lost during adaptation to parasitism. The free-living ancestor contained a broad repertoire of genes many of which were repurposed for parasitic processes, such as extracellular proteins, components of a motility apparatus, and DNA- and RNA-binding protein families. Based on transcriptome analyses across 36 environmental conditions, Chromera orthologs of apicomplexan invasion-related motility genes were co-regulated with genes encoding the flagellar apparatus, supporting the functional contribution of flagella to the evolution of invasion machinery. This study provides insights into how obligate parasites with diverse life strategies arose from a once free-living phototrophic marine alga. © Woo et al.

  10. Chromerid genomes reveal the evolutionary path from photosynthetic algae to obligate intracellular parasites

    KAUST Repository

    Woo, Yong; Ansari, Hifzur Rahman; Otto, Thomas D.; Linger, Christen M K; Olisko, Martin K.; Michá lek, Jan; Saxena, Alka; Shanmugam, Dhanasekaran; Tayyrov, Annageldi; Veluchamy, Alaguraj; Ali, Shahjahan; Bernal, Axel; Del Campo, Javier; Cihlá ř, Jaromí r; Flegontov, Pavel; Gornik, Sebastian G.; Hajdušková , Eva; Horá k, Aleš; Janouškovec, Jan; Katris, Nicholas J.; Mast, Fred D.; Miranda-Saavedra, Diego; Mourier, Tobias; Naeem, Raeece; Nair, Mridul; Panigrahi, Aswini Kumar; Rawlings, Neil D.; Padron Regalado, Eriko; Ramaprasad, Abhinay; Samad, Nadira; Tomčala, Aleš; Wilkes, Jon; Neafsey, Daniel E.; Doerig, Christian; Bowler, Chris; Keeling, Patrick J.; Roos, David S.; Dacks, Joel B.; Templeton, Thomas J.; Waller, Ross F.; Lukeš, Julius; Oborní k, Miroslav; Pain, Arnab

    2015-01-01

    The eukaryotic phylum Apicomplexa encompasses thousands of obligate intracellular parasites of humans and animals with immense socio-economic and health impacts. We sequenced nuclear genomes of Chromera velia and Vitrella brassicaformis, free-living non-parasitic photosynthetic algae closely related to apicomplexans. Proteins from key metabolic pathways and from the endomembrane trafficking systems associated with a free-living lifestyle have been progressively and non-randomly lost during adaptation to parasitism. The free-living ancestor contained a broad repertoire of genes many of which were repurposed for parasitic processes, such as extracellular proteins, components of a motility apparatus, and DNA- and RNA-binding protein families. Based on transcriptome analyses across 36 environmental conditions, Chromera orthologs of apicomplexan invasion-related motility genes were co-regulated with genes encoding the flagellar apparatus, supporting the functional contribution of flagella to the evolution of invasion machinery. This study provides insights into how obligate parasites with diverse life strategies arose from a once free-living phototrophic marine alga. © Woo et al.

  11. Adaptations in the energy metabolism of parasites

    NARCIS (Netherlands)

    van Grinsven, K.W.A.|info:eu-repo/dai/nl/304833436

    2009-01-01

    For this thesis fundamental research was performed on the metabolic adaptations found in parasites. Studying the adaptations in parasite metabolisms leads to a better understanding of parasite bioenergetics and can also result in the identification of new anti-parasitic drug targets. We focussed on

  12. Pervasiveness of parasites in pollinators.

    Directory of Open Access Journals (Sweden)

    Sophie E F Evison

    Full Text Available Many pollinator populations are declining, with large economic and ecological implications. Parasites are known to be an important factor in the some of the population declines of honey bees and bumblebees, but little is known about the parasites afflicting most other pollinators, or the extent of interspecific transmission or vectoring of parasites. Here we carry out a preliminary screening of pollinators (honey bees, five species of bumblebee, three species of wasp, four species of hoverfly and three genera of other bees in the UK for parasites. We used molecular methods to screen for six honey bee viruses, Ascosphaera fungi, Microsporidia, and Wolbachia intracellular bacteria. We aimed simply to detect the presence of the parasites, encompassing vectoring as well as actual infections. Many pollinators of all types were positive for Ascosphaera fungi, while Microsporidia were rarer, being most frequently found in bumblebees. We also detected that most pollinators were positive for Wolbachia, most probably indicating infection with this intracellular symbiont, and raising the possibility that it may be an important factor in influencing host sex ratios or fitness in a diversity of pollinators. Importantly, we found that about a third of bumblebees (Bombus pascuorum and Bombus terrestris and a third of wasps (Vespula vulgaris, as well as all honey bees, were positive for deformed wing virus, but that this virus was not present in other pollinators. Deformed wing virus therefore does not appear to be a general parasite of pollinators, but does interact significantly with at least three species of bumblebee and wasp. Further work is needed to establish the identity of some of the parasites, their spatiotemporal variation, and whether they are infecting the various pollinator species or being vectored. However, these results provide a first insight into the diversity, and potential exchange, of parasites in pollinator communities.

  13. Insights into the Initiation of Eukaryotic DNA Replication.

    Science.gov (United States)

    Bruck, Irina; Perez-Arnaiz, Patricia; Colbert, Max K; Kaplan, Daniel L

    2015-01-01

    The initiation of DNA replication is a highly regulated event in eukaryotic cells to ensure that the entire genome is copied once and only once during S phase. The primary target of cellular regulation of eukaryotic DNA replication initiation is the assembly and activation of the replication fork helicase, the 11-subunit assembly that unwinds DNA at a replication fork. The replication fork helicase, called CMG for Cdc45-Mcm2-7, and GINS, assembles in S phase from the constituent Cdc45, Mcm2-7, and GINS proteins. The assembly and activation of the CMG replication fork helicase during S phase is governed by 2 S-phase specific kinases, CDK and DDK. CDK stimulates the interaction between Sld2, Sld3, and Dpb11, 3 initiation factors that are each required for the initiation of DNA replication. DDK, on the other hand, phosphorylates the Mcm2, Mcm4, and Mcm6 subunits of the Mcm2-7 complex. Sld3 recruits Cdc45 to Mcm2-7 in a manner that depends on DDK, and recent work suggests that Sld3 binds directly to Mcm2-7 and also to single-stranded DNA. Furthermore, recent work demonstrates that Sld3 and its human homolog Treslin substantially stimulate DDK phosphorylation of Mcm2. These data suggest that the initiation factor Sld3/Treslin coordinates the assembly and activation of the eukaryotic replication fork helicase by recruiting Cdc45 to Mcm2-7, stimulating DDK phosphorylation of Mcm2, and binding directly to single-stranded DNA as the origin is melted.

  14. [Structure and evolution of the eukaryotic FANCJ-like proteins].

    Science.gov (United States)

    Wuhe, Jike; Zefeng, Wu; Sanhong, Fan; Xuguang, Xi

    2015-02-01

    The FANCJ-like protein family is a class of ATP-dependent helicases that can catalytically unwind duplex DNA along the 5'-3' direction. It is involved in the processes of DNA damage repair, homologous recombination and G-quadruplex DNA unwinding, and plays a critical role in maintaining genome integrity. In this study, we systemically analyzed FNACJ-like proteins from 47 eukaryotic species and discussed their sequences diversity, origin and evolution, motif organization patterns and spatial structure differences. Four members of FNACJ-like proteins, including XPD, CHL1, RTEL1 and FANCJ, were found in eukaryotes, but some of them were seriously deficient in most fungi and some insects. For example, the Zygomycota fungi lost RTEL1, Basidiomycota and Ascomycota fungi lost RTEL1 and FANCJ, and Diptera insect lost FANCJ. FANCJ-like proteins contain canonical motor domains HD1 and HD2, and the HD1 domain further integrates with three unique domains Fe-S, Arch and Extra-D. Fe-S and Arch domains are relatively conservative in all members of the family, but the Extra-D domain is lost in XPD and differs from one another in rest members. There are 7, 10 and 2 specific motifs found from the three unique domains respectively, while 5 and 12 specific motifs are found from HD1 and HD2 domains except the conserved motifs reported previously. By analyzing the arrangement pattern of these specific motifs, we found that RTEL1 and FANCJ are more closer and share two specific motifs Vb2 and Vc in HD2 domain, which are likely related with their G-quadruplex DNA unwinding activity. The evidence of evolution showed that FACNJ-like proteins were originated from a helicase, which has a HD1 domain inserted by extra Fe-S domain and Arch domain. By three continuous gene duplication events and followed specialization, eukaryotes finally possessed the current four members of FANCJ-like proteins.

  15. Challenges in Whole-Genome Annotation of Pyrosequenced Eukaryotic Genomes

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, Alan; Grigoriev, Igor

    2009-04-17

    Pyrosequencing technologies such as 454/Roche and Solexa/Illumina vastly lower the cost of nucleotide sequencing compared to the traditional Sanger method, and thus promise to greatly expand the number of sequenced eukaryotic genomes. However, the new technologies also bring new challenges such as shorter reads and new kinds and higher rates of sequencing errors, which complicate genome assembly and gene prediction. At JGI we are deploying 454 technology for the sequencing and assembly of ever-larger eukaryotic genomes. Here we describe our first whole-genome annotation of a purely 454-sequenced fungal genome that is larger than a yeast (>30 Mbp). The pezizomycotine (filamentous ascomycote) Aspergillus carbonarius belongs to the Aspergillus section Nigri species complex, members of which are significant as platforms for bioenergy and bioindustrial technology, as members of soil microbial communities and players in the global carbon cycle, and as agricultural toxigens. Application of a modified version of the standard JGI Annotation Pipeline has so far predicted ~;;10k genes. ~;;12percent of these preliminary annotations suffer a potential frameshift error, which is somewhat higher than the ~;;9percent rate in the Sanger-sequenced and conventionally assembled and annotated genome of fellow Aspergillus section Nigri member A. niger. Also,>90percent of A. niger genes have potential homologs in the A. carbonarius preliminary annotation. Weconclude, and with further annotation and comparative analysis expect to confirm, that 454 sequencing strategies provide a promising substrate for annotation of modestly sized eukaryotic genomes. We will also present results of annotation of a number of other pyrosequenced fungal genomes of bioenergy interest.

  16. Recognition of extremophilic archaeal viruses by eukaryotic cells

    DEFF Research Database (Denmark)

    Uldahl, Kristine Buch; Wu, Linping; Hall, Arnaldur

    2016-01-01

    followed viral uptake, intracellular trafficking and cell viability in human endothelial cells of brain (hCMEC/D3 cells) and umbilical vein (HUVEC) origin. Whereas SMV1 is efficiently internalized into both types of human cells, SSV2 differentiates between HUVECs and hCMEC/D3 cells, thus opening a path......Viruses from the third domain of life, Archaea, exhibit unusual features including extreme stability that allow their survival in harsh environments. In addition, these species have never been reported to integrate into human or any other eukaryotic genomes, and could thus serve for exploration...

  17. Global issues in allergy and immunology: Parasitic infections and allergy.

    Science.gov (United States)

    Cruz, Alvaro A; Cooper, Philip J; Figueiredo, Camila A; Alcantara-Neves, Neuza M; Rodrigues, Laura C; Barreto, Mauricio L

    2017-11-01

    Allergic diseases are on the increase globally in parallel with a decrease in parasitic infection. The inverse association between parasitic infections and allergy at an ecological level suggests a causal association. Studies in human subjects have generated a large knowledge base on the complexity of the interrelationship between parasitic infection and allergy. There is evidence for causal links, but the data from animal models are the most compelling: despite the strong type 2 immune responses they induce, helminth infections can suppress allergy through regulatory pathways. Conversely, many helminths can cause allergic-type inflammation, including symptoms of "classical" allergic disease. From an evolutionary perspective, subjects with an effective immune response against helminths can be more susceptible to allergy. This narrative review aims to inform readers of the most relevant up-to-date evidence on the relationship between parasites and allergy. Experiments in animal models have demonstrated the potential benefits of helminth infection or administration of helminth-derived molecules on chronic inflammatory diseases, but thus far, clinical trials in human subjects have not demonstrated unequivocal clinical benefits. Nevertheless, there is sufficiently strong evidence to support continued investigation of the potential benefits of helminth-derived therapies for the prevention or treatment of allergic and other inflammatory diseases. Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

  18. Paleoparasitology: the origin of human parasites

    Directory of Open Access Journals (Sweden)

    Adauto Araujo

    2013-09-01

    Full Text Available Parasitism is composed by three subsystems: the parasite, the host, and the environment. There are no organisms that cannot be parasitized. The relationship between a parasite and its host species most of the time do not result in damage or disease to the host. However, in a parasitic disease the presence of a given parasite is always necessary, at least in a given moment of the infection. Some parasite species that infect humans were inherited from pre-hominids, and were shared with other phylogenetically close host species, but other parasite species were acquired from the environment as humans evolved. Human migration spread inherited parasites throughout the globe. To recover and trace the origin and evolution of infectious diseases, paleoparasitology was created. Paleoparasitology is the study of parasites in ancient material, which provided new information on the evolution, paleoepidemiology, ecology and phylogenetics of infectious diseases.

  19. Noise Depression of Parasitic Capacitance for Frequency Detection of Micromechanical Bulk Disk Resonator

    DEFF Research Database (Denmark)

    Tang, Meng; Cagliani, Alberto; Escouflaire, Marie

    2010-01-01

    the frequency noise of the system. A capacitor cancellation circuit is used to subtract the parasitic capacitor. Measurements are conducted before and after the cancellation, and results show that after cancellation, the anti resonance is suppressed and the frequency noise is decreased, thus decreasing...

  20. Building the perfect parasite: cell division in apicomplexa.

    Directory of Open Access Journals (Sweden)

    Boris Striepen

    2007-06-01

    Full Text Available Apicomplexans are pathogens responsible for malaria, toxoplasmosis, and crytposporidiosis in humans, and a wide range of livestock diseases. These unicellular eukaryotes are stealthy invaders, sheltering from the immune response in the cells of their hosts, while at the same time tapping into these cells as source of nutrients. The complexity and beauty of the structures formed during their intracellular development have made apicomplexans the darling of electron microscopists. Dramatic technological progress over the last decade has transformed apicomplexans into respectable genetic model organisms. Extensive genomic resources are now available for many apicomplexan species. At the same time, parasite transfection has enabled researchers to test the function of specific genes through reverse and forward genetic approaches with increasing sophistication. Transfection also introduced the use of fluorescent reporters, opening the field to dynamic real time microscopic observation. Parasite cell biologists have used these tools to take a fresh look at a classic problem: how do apicomplexans build the perfect invasion machine, the zoite, and how is this process fine-tuned to fit the specific niche of each pathogen in this ancient and very diverse group? This work has unearthed a treasure trove of novel structures and mechanisms that are the focus of this review.

  1. Modifying chemotherapy response by targeted inhibition of eukaryotic initiation factor 4A

    International Nuclear Information System (INIS)

    Cencic, R; Robert, F; Galicia-Vázquez, G; Malina, A; Ravindar, K; Somaiah, R; Pierre, P; Tanaka, J; Deslongchamps, P; Pelletier, J

    2013-01-01

    Translation is regulated predominantly at the initiation phase by several signal transduction pathways that are often usurped in human cancers, including the PI3K/Akt/mTOR axis. mTOR exerts unique administration over translation by regulating assembly of eukaryotic initiation factor (eIF) 4F, a heterotrimeric complex responsible for recruiting 40S ribosomes (and associated factors) to mRNA 5′ cap structures. Hence, there is much interest in targeted therapies that block eIF4F activity to assess the consequences on tumor cell growth and chemotherapy response. We report here that hippuristanol (Hipp), a translation initiation inhibitor that selectively inhibits the eIF4F RNA helicase subunit, eIF4A, resensitizes Eμ-Myc lymphomas to DNA damaging agents, including those that overexpress eIF4E—a modifier of rapamycin responsiveness. As Mcl-1 levels are significantly affected by Hipp, combining its use with the Bcl-2 family inhibitor, ABT-737, leads to a potent synergistic response in triggering cell death in mouse and human lymphoma and leukemia cells. Suppression of eIF4AI using RNA interference also synergized with ABT-737 in murine lymphomas, highlighting eIF4AI as a therapeutic target for modulating tumor cell response to chemotherapy

  2. Eukaryotic snoRNAs: a paradigm for gene expression flexibility.

    Science.gov (United States)

    Dieci, Giorgio; Preti, Milena; Montanini, Barbara

    2009-08-01

    Small nucleolar RNAs (snoRNAs) are one of the most ancient and numerous families of non-protein-coding RNAs (ncRNAs). The main function of snoRNAs - to guide site-specific rRNA modification - is the same in Archaea and all eukaryotic lineages. In contrast, as revealed by recent genomic and RNomic studies, their genomic organization and expression strategies are the most varied. Seemingly snoRNA coding units have adopted, in the course of evolution, all the possible ways of being transcribed, thus providing a unique paradigm of gene expression flexibility. By focusing on representative fungal, plant and animal genomes, we review here all the documented types of snoRNA gene organization and expression, and we provide a comprehensive account of snoRNA expressional freedom by precisely estimating the frequency, in each genome, of each type of genomic organization. We finally discuss the relevance of snoRNA genomic studies for our general understanding of ncRNA family evolution and expression in eukaryotes.

  3. Characterization of an eukaryotic peptide deformylase from Plasmodium falciparum.

    Science.gov (United States)

    Bracchi-Ricard, V; Nguyen, K T; Zhou, Y; Rajagopalan, P T; Chakrabarti, D; Pei, D

    2001-12-15

    Ribosomal protein synthesis in eubacteria and eukaryotic organelles initiates with an N-formylmethionyl-tRNA(i), resulting in N-terminal formylation of all nascent polypeptides. Peptide deformylase (PDF) catalyzes the subsequent removal of the N-terminal formyl group from the majority of bacterial proteins. Until recently, PDF has been thought as an enzyme unique to the bacterial kingdom. Searches of the genomic DNA databases identified several genes that encode proteins of high sequence homology to bacterial PDF from eukaryotic organisms. The cDNA encoding Plasmodium falciparum PDF (PfPDF) has been cloned and overexpressed in Escherichia coli. The recombinant protein is catalytically active in deformylating N-formylated peptides, shares many of the properties of bacterial PDF, and is inhibited by specific PDF inhibitors. Western blot analysis indicated expression of mature PfPDF in trophozoite, schizont, and segmenter stages of intraerythrocytic development. These results provide strong evidence that a functional PDF is present in P. falciparum. In addition, PDF inhibitors inhibited the growth of P. falciparum in the intraerythrocytic culture. (c)2001 Elsevier Science.

  4. Universal Temporal Profile of Replication Origin Activation in Eukaryotes

    Science.gov (United States)

    Goldar, Arach

    2011-03-01

    The complete and faithful transmission of eukaryotic genome to daughter cells involves the timely duplication of mother cell's DNA. DNA replication starts at multiple chromosomal positions called replication origin. From each activated replication origin two replication forks progress in opposite direction and duplicate the mother cell's DNA. While it is widely accepted that in eukaryotic organisms replication origins are activated in a stochastic manner, little is known on the sources of the observed stochasticity. It is often associated to the population variability to enter S phase. We extract from a growing Saccharomyces cerevisiae population the average rate of origin activation in a single cell by combining single molecule measurements and a numerical deconvolution technique. We show that the temporal profile of the rate of origin activation in a single cell is similar to the one extracted from a replicating cell population. Taking into account this observation we exclude the population variability as the origin of observed stochasticity in origin activation. We confirm that the rate of origin activation increases in the early stage of S phase and decreases at the latter stage. The population average activation rate extracted from single molecule analysis is in prefect accordance with the activation rate extracted from published micro-array data, confirming therefore the homogeneity and genome scale invariance of dynamic of replication process. All these observations point toward a possible role of replication fork to control the rate of origin activation.

  5. Marine biofilm bacteria evade eukaryotic predation by targeted chemical defense.

    Directory of Open Access Journals (Sweden)

    Carsten Matz

    Full Text Available Many plants and animals are defended from predation or herbivory by inhibitory secondary metabolites, which in the marine environment are very common among sessile organisms. Among bacteria, where there is the greatest metabolic potential, little is known about chemical defenses against bacterivorous consumers. An emerging hypothesis is that sessile bacterial communities organized as biofilms serve as bacterial refuge from predation. By testing growth and survival of two common bacterivorous nanoflagellates, we find evidence that chemically mediated resistance against protozoan predators is common among biofilm populations in a diverse set of marine bacteria. Using bioassay-guided chemical and genetic analysis, we identified one of the most effective antiprotozoal compounds as violacein, an alkaloid that we demonstrate is produced predominately within biofilm cells. Nanomolar concentrations of violacein inhibit protozoan feeding by inducing a conserved eukaryotic cell death program. Such biofilm-specific chemical defenses could contribute to the successful persistence of biofilm bacteria in various environments and provide the ecological and evolutionary context for a number of eukaryote-targeting bacterial metabolites.

  6. Cross-species complementation of bacterial- and eukaryotic-type cardiolipin synthases

    Directory of Open Access Journals (Sweden)

    Petra Gottier

    2017-11-01

    Full Text Available The glycerophospholipid cardiolipin is a unique constituent of bacterial and mitochondrial membranes. It is involved in forming and stabilizing high molecular mass membrane protein complexes and in maintaining membrane architecture. Absence of cardiolipin leads to reduced efficiency of the electron transport chain, decreased membrane potential, and, ultimately, impaired respiratory metabolism. For the protozoan parasite Trypanosoma brucei cardiolipin synthesis is essential for survival, indicating that the enzymes involved in cardiolipin production represent potential drug targets. T. brucei cardiolipin synthase (TbCLS is unique as it belongs to the family of phospholipases D (PLD, harboring a prokaryotic-type cardiolipin synthase (CLS active site domain. In contrast, most other eukaryotic CLS, including the yeast ortholog ScCrd1, are members of the CDP-alcohol phosphatidyl­ transferase family. To study if these mechanistically distinct CLS enzymes are able to catalyze cardiolipin production in a cell that normally expresses a different type of CLS, we expressed TbCLS and ScCrd1 in CLS-deficient yeast and trypanosome strains, respectively. Our results show that TbCLS complemented cardiolipin production in CRD1 knockout yeast and partly restored wild-type colony forming capability under stress conditions. Remarkably, CL remodeling appeared to be impaired in the transgenic construct, suggesting that CL production and remodeling are tightly coupled processes that may require a clustering of the involved proteins into specific CL-synthesizing domains. In contrast, no complementation was observed by heterologous expression of ScCrd1 in conditional TbCLS knockout trypanosomes, despite proper mitochondrial targeting of the protein.

  7. Gene Expression Contributes to the Recent Evolution of Host Resistance in a Model Host Parasite System

    Directory of Open Access Journals (Sweden)

    Brian K. Lohman

    2017-09-01

    Full Text Available Heritable population differences in immune gene expression following infection can reveal mechanisms of host immune evolution. We compared gene expression in infected and uninfected threespine stickleback (Gasterosteus aculeatus from two natural populations that differ in resistance to a native cestode parasite, Schistocephalus solidus. Genes in both the innate and adaptive immune system were differentially expressed as a function of host population, infection status, and their interaction. These genes were enriched for loci controlling immune functions known to differ between host populations or in response to infection. Coexpression network analysis identified two distinct processes contributing to resistance: parasite survival and suppression of growth. Comparing networks between populations showed resistant fish have a dynamic expression profile while susceptible fish are static. In summary, recent evolutionary divergence between two vertebrate populations has generated population-specific gene expression responses to parasite infection, affecting parasite establishment and growth.

  8. Deconstructing continuous flash suppression.

    Science.gov (United States)

    Yang, Eunice; Blake, Randolph

    2012-03-08

    In this paper, we asked to what extent the depth of interocular suppression engendered by continuous flash suppression (CFS) varies depending on spatiotemporal properties of the suppressed stimulus and CFS suppressor. An answer to this question could have implications for interpreting the results in which CFS influences the processing of different categories of stimuli to different extents. In a series of experiments, we measured the selectivity and depth of suppression (i.e., elevation in contrast detection thresholds) as a function of the visual features of the stimulus being suppressed and the stimulus evoking suppression, namely, the popular "Mondrian" CFS stimulus (N. Tsuchiya & C. Koch, 2005). First, we found that CFS differentially suppresses the spatial components of the suppressed stimulus: Observers' sensitivity for stimuli of relatively low spatial frequency or cardinally oriented features was more strongly impaired in comparison to high spatial frequency or obliquely oriented stimuli. Second, we discovered that this feature-selective bias primarily arises from the spatiotemporal structure of the CFS stimulus, particularly within information residing in the low spatial frequency range and within the smooth rather than abrupt luminance changes over time. These results imply that this CFS stimulus operates by selectively attenuating certain classes of low-level signals while leaving others to be potentially encoded during suppression. These findings underscore the importance of considering the contribution of low-level features in stimulus-driven effects that are reported under CFS.

  9. Microsporidia are natural intracellular parasites of the nematode Caenorhabditis elegans.

    Science.gov (United States)

    Troemel, Emily R; Félix, Marie-Anne; Whiteman, Noah K; Barrière, Antoine; Ausubel, Frederick M

    2008-12-09

    For decades the soil nematode Caenorhabditis elegans has been an important model system for biology, but little is known about its natural ecology. Recently, C. elegans has become the focus of studies of innate immunity and several pathogens have been shown to cause lethal intestinal infections in C. elegans. However none of these pathogens has been shown to invade nematode intestinal cells, and no pathogen has been isolated from wild-caught C. elegans. Here we describe an intracellular pathogen isolated from wild-caught C. elegans that we show is a new species of microsporidia. Microsporidia comprise a large class of eukaryotic intracellular parasites that are medically and agriculturally important, but poorly understood. We show that microsporidian infection of the C. elegans intestine proceeds through distinct stages and is transmitted horizontally. Disruption of a conserved cytoskeletal structure in the intestine called the terminal web correlates with the release of microsporidian spores from infected cells, and appears to be part of a novel mechanism by which intracellular pathogens exit from infected cells. Unlike in bacterial intestinal infections, the p38 MAPK and insulin/insulin-like growth factor (IGF) signaling pathways do not appear to play substantial roles in resistance to microsporidian infection in C. elegans. We found microsporidia in multiple wild-caught isolates of Caenorhabditis nematodes from diverse geographic locations. These results indicate that microsporidia are common parasites of C. elegans in the wild. In addition, the interaction between C. elegans and its natural microsporidian parasites provides a system in which to dissect intracellular intestinal infection in vivo and insight into the diversity of pathogenic mechanisms used by intracellular microbes.

  10. Genome Evolution of Plant-Parasitic Nematodes.

    Science.gov (United States)

    Kikuchi, Taisei; Eves-van den Akker, Sebastian; Jones, John T

    2017-08-04

    Plant parasitism has evolved independently on at least four separate occasions in the phylum Nematoda. The application of next-generation sequencing (NGS) to plant-parasitic nematodes has allowed a wide range of genome- or transcriptome-level comparisons, and these have identified genome adaptations that enable parasitism of plants. Current genome data suggest that horizontal gene transfer, gene family expansions, evolution of new genes that mediate interactions with the host, and parasitism-specific gene regulation are important adaptations that allow nematodes to parasitize plants. Sequencing of a larger number of nematode genomes, including plant parasites that show different modes of parasitism or that have evolved in currently unsampled clades, and using free-living taxa as comparators would allow more detailed analysis and a better understanding of the organization of key genes within the genomes. This would facilitate a more complete understanding of the way in which parasitism has shaped the genomes of plant-parasitic nematodes.

  11. Taming Parasites by Tailoring Them

    Directory of Open Access Journals (Sweden)

    Bingjian Ren

    2017-07-01

    Full Text Available The next-generation gene editing based on CRISPR (clustered regularly interspaced short palindromic repeats has been successfully implemented in a wide range of organisms including some protozoan parasites. However, application of such a versatile game-changing technology in molecular parasitology remains fairly underexplored. Here, we briefly introduce state-of-the-art in human and mouse research and usher new directions to drive the parasitology research in the years to come. In precise, we outline contemporary ways to embolden existing apicomplexan and kinetoplastid parasite models by commissioning front-line gene-tailoring methods, and illustrate how we can break the enduring gridlock of gene manipulation in non-model parasitic protists to tackle intriguing questions that remain long unresolved otherwise. We show how a judicious solicitation of the CRISPR technology can eventually balance out the two facets of pathogen-host interplay.

  12. An Interactive Exercise To Learn Eukaryotic Cell Structure and Organelle Function.

    Science.gov (United States)

    Klionsky, Daniel J.; Tomashek, John J.

    1999-01-01

    Describes a cooperative, interactive problem-solving exercise for studying eukaryotic cell structure and function. Highlights the dynamic aspects of movement through the cell. Contains 15 references. (WRM)

  13. [MiRNA system in unicellular eukaryotes and its evolutionary implications].

    Science.gov (United States)

    Zhang, Yan-Qiong; Wen, Jian-Fan

    2010-02-01

    microRNAs (miRNAs) in higher multicellular eukaryotes have been extensively studied in recent years. Great progresses have also been achieved for miRNAs in unicellular eukaryotes. All these studies not only enrich our knowledge about the complex expression regulation system in diverse organisms, but also have evolutionary significance for understanding the origin of this system. In this review, Authors summarize the recent advance in the studies of miRNA in unicellular eukaryotes, including that on the most primitive unicellular eukaryote--Giardia. The origin and evolution of miRNA system is also discussed.

  14. Parasites and immunotherapy: with or against?

    Science.gov (United States)

    Yousofi Darani, Hossein; Yousefi, Morteza; Safari, Marzieh; Jafari, Rasool

    2016-06-01

    Immunotherapy is a sort of therapy in which antibody or antigen administrates to the patient in order to treat or reduce the severity of complications of disease. This kind of treatment practiced in a wide variety of diseases including infectious diseases, autoimmune disorders, cancers and allergy. Successful and unsuccessful immunotherapeutic strategies have been practiced in variety of parasitic infections. On the other hand parasites or parasite antigens have also been considered for immunotherapy against other diseases such as cancer, asthma and multiple sclerosis. In this paper immunotherapy against common parasitic infections, and also immunotherapy of cancer, asthma and multiple sclerosis with parasites or parasite antigens have been reviewed.

  15. The fish parasite Ichthyophthirius multifiliis

    DEFF Research Database (Denmark)

    Jørgensen, Louise von Gersdorff

    2017-01-01

    Ichthyophthirius multifiliis, the causative agent of white spot disease (ichthyophthiriasis) is a major burden for fish farmers and aquarists globally. The parasite infects the skin and the gills of freshwater fish, which may acquire a protective adaptive immune response against this disease...... and recognition of carcinogenic and environmentally damaging effects the most efficient compounds are prohibited. A continuous search for novel substances, which are highly effective against the parasites and harmless for the fish is ongoing. These compounds should be environmentally friendly and cost...

  16. Automatic generation of gene finders for eukaryotic species

    DEFF Research Database (Denmark)

    Terkelsen, Kasper Munch; Krogh, A.

    2006-01-01

    and quality of reliable gene annotation grows. Results We present a procedure, Agene, that automatically generates a species-specific gene predictor from a set of reliable mRNA sequences and a genome. We apply a Hidden Markov model (HMM) that implements explicit length distribution modelling for all gene......Background The number of sequenced eukaryotic genomes is rapidly increasing. This means that over time it will be hard to keep supplying customised gene finders for each genome. This calls for procedures to automatically generate species-specific gene finders and to re-train them as the quantity...... structure blocks using acyclic discrete phase type distributions. The state structure of the each HMM is generated dynamically from an array of sub-models to include only gene features represented in the training set. Conclusion Acyclic discrete phase type distributions are well suited to model sequence...

  17. Nucleosome mediated crosstalk between transcription factors at eukaryotic enhancers

    International Nuclear Information System (INIS)

    Teif, Vladimir B; Rippe, Karsten

    2011-01-01

    A recent study of transcription regulation in Drosophila embryonic development revealed a complex non-monotonic dependence of gene expression on the distance between binding sites of repressor and activator proteins at the corresponding enhancer cis-regulatory modules (Fakhouri et al 2010 Mol. Syst. Biol. 6 341). The repressor efficiency was high at small separations, low around 30 bp, reached a maximum at 50–60 bp, and decreased at larger distances to the activator binding sites. Here, we propose a straightforward explanation for the distance dependence of repressor activity by considering the effect of the presence of a nucleosome. Using a method that considers partial unwrapping of nucleosomal DNA from the histone octamer core, we calculated the dependence of activator binding on the repressor–activator distance and found a quantitative agreement with the distance dependence reported for the Drosophila enhancer element. In addition, the proposed model offers explanations for other distance-dependent effects at eukaryotic enhancers. (communication)

  18. The biology of eukaryotic promoter prediction - a review

    DEFF Research Database (Denmark)

    Pedersen, Anders Gorm; Baldi, Pierre; Chauvin, Yves

    1999-01-01

    between functional promoters has been estimated to be in the range of 30-40 kilobases. Although it is conceivable that some of these predicted promoters correspond to cryptic initiation sites that are used in vivo, it is likely that most are false positives. This suggests that it is important to carefully......Computational prediction of eukaryotic promoters from the nucleotide sequence is one of the most attractive problems in sequence analysis today, but it is also a very difficult one. Thus, current methods predict in the order of one promoter per kilobase in human DNA, while the average distance...... reconsider the biological data that forms the basis of current algorithms, and we here present a review of data that may be useful in this regard. The review covers the following topics: (1) basal transcription and core promoters, (2) activated transcription and transcription factor binding sites, (3) Cp...

  19. A general strategy to construct small molecule biosensors in eukaryotes.

    Science.gov (United States)

    Feng, Justin; Jester, Benjamin W; Tinberg, Christine E; Mandell, Daniel J; Antunes, Mauricio S; Chari, Raj; Morey, Kevin J; Rios, Xavier; Medford, June I; Church, George M; Fields, Stanley; Baker, David

    2015-12-29

    Biosensors for small molecules can be used in applications that range from metabolic engineering to orthogonal control of transcription. Here, we produce biosensors based on a ligand-binding domain (LBD) by using a method that, in principle, can be applied to any target molecule. The LBD is fused to either a fluorescent protein or a transcriptional activator and is destabilized by mutation such that the fusion accumulates only in cells containing the target ligand. We illustrate the power of this method by developing biosensors for digoxin and progesterone. Addition of ligand to yeast, mammalian, or plant cells expressing a biosensor activates transcription with a dynamic range of up to ~100-fold. We use the biosensors to improve the biotransformation of pregnenolone to progesterone in yeast and to regulate CRISPR activity in mammalian cells. This work provides a general methodology to develop biosensors for a broad range of molecules in eukaryotes.

  20. Cytoplasmic Flow Enhances Organelle Dispersion in Eukaryotic Cells

    Science.gov (United States)

    Koslover, Elena; Mogre, Saurabh; Chan, Caleb; Theriot, Julie

    The cytoplasm of a living cell is an active environment through which intracellular components move and mix. We explore, using theoretical modeling coupled with microrheological measurements, the efficiency of particle dispersion via different modes of transport within this active environment. In particular, we focus on the role of cytoplasmic flow over different scales in contributing to organelle transport within two different cell types. In motile neutrophil cells, we show that bulk fluid flow associated with rapid cell deformation enhances particle transport to and from the cell periphery. In narrow fungal hyphae, localized flows due to hydrodynamic entrainment are shown to contribute to optimally efficient organelle dispersion. Our results highlight the importance of non-traditional modes of transport associated with flow of the cytoplasmic fluid in the distribution of organelles throughout eukaryotic cells.

  1. Ancient photosynthetic eukaryote biofilms in an Atacama Desert coastal cave

    Science.gov (United States)

    Azua-Bustos, A.; Gonzalez-Silva, C.; Mancilla, R.A.; Salas, L.; Palma, R.E.; Wynne, J.J.; McKay, C.P.; Vicuna, R.

    2009-01-01

    Caves offer a stable and protected environment from harsh and changing outside prevailing conditions. Hence, they represent an interesting habitat for studying life in extreme environments. Here, we report the presence of a member of the ancient eukaryote red algae Cyanidium group in a coastal cave of the hyperarid Atacama Desert. This microorganism was found to form a seemingly monospecific biofilm growing under extremely low photon flux levels. Our work suggests that this species, Cyanidium sp. Atacama, is a new member of a recently proposed novel monophyletic lineage of mesophilic "cave" Cyanidium sp., distinct from the remaining three other lineages which are all thermo-acidophilic. The cave described in this work may represent an evolutionary island for life in the midst of the Atacama Desert. ?? Springer Science + Business Media, LLC 2009.

  2. Short RNA guides cleavage by eukaryotic RNase III.

    Directory of Open Access Journals (Sweden)

    Bruno Lamontagne

    Full Text Available In eukaryotes, short RNAs guide a variety of enzymatic activities that range from RNA editing to translation repression. It is hypothesized that pre-existing proteins evolved to bind and use guide RNA during evolution. However, the capacity of modern proteins to adopt new RNA guides has never been demonstrated. Here we show that Rnt1p, the yeast orthologue of the bacterial dsRNA-specific RNase III, can bind short RNA transcripts and use them as guides for sequence-specific cleavage. Target cleavage occurred at a constant distance from the Rnt1p binding site, leaving the guide RNA intact for subsequent cleavage. Our results indicate that RNase III may trigger sequence-specific RNA degradation independent of the RNAi machinery, and they open the road for a new generation of precise RNA silencing tools that do not trigger a dsRNA-mediated immune response.

  3. Synthesis of eukaryotic lipid biomarkers in the bacterial domain

    Science.gov (United States)

    Welander, P. V.; Banta, A. B.; Lee, A. K.; Wei, J. H.

    2017-12-01

    Lipid biomarkers are organic molecules preserved in sediments and sedimentary rocks that can function as geological proxies for certain microbial taxa or for specific environmental conditions. These molecular fossils provide a link between organisms and their environments in both modern and ancient settings and have afforded significant insight into ancient climatic events, mass extinctions, and various evolutionary transitions throughout Earth's history. However, the proper interpretation of lipid biomarkers is dependent on a broad understanding of their diagenetic precursors in modern systems. This includes understanding the taphonomic transformations that these molecules undergo, their biosynthetic pathways, and the ecological conditions that affect their cellular production. In this study, we focus on one group of lipid biomarkers - the sterols. These are polycyclic isoprenoidal lipids that have a high preservation potential and play a critical role in the physiology of most eukaryotes. However, the synthesis and function of these lipids in the bacterial domain has not been fully explored. Here we utilize a combination of bioinformatics, microbial genetics, and biochemistry to demonstrate that bacterial sterol producers are more prevalent in environmental metagenomic samples than in the genomic databases of cultured organisms and to identify novel proteins required to synthesize and modify sterols in bacteria. These proteins represent a distinct pathway for sterol synthesis exclusive to bacteria and indicate that sterol synthesis in bacteria may have evolved independently of eukaryotic sterol biosynthesis. Taken together, these results demonstrate how studies in extant bacteria can provide insight into the biological sources and the biosynthetic pathways of specific lipid biomarkers and in turn may allow for more robust interpretation of biomarker signatures.

  4. Molecular basis of Trypanosoma cruzi and Leishmania interaction with their host(s): exploitation of immune and defense mechanisms by the parasite leading to persistence and chronicity, features reminiscent of immune system evasion strategies in cancer diseases.

    Science.gov (United States)

    Ouaissi, Ali; Ouaissi, Mehdi

    2005-01-01

    A number of features occurring during host-parasite interactions in Chagas disease caused by the protozoan parasite, Trypanosoma cruzi, and Leishmaniasis, caused by a group of kinetoplastid protozoan parasites are reminiscent of those observed in cancer diseases. In fact,although the cancer is not a single disease, and that T.cruzi and Leishmania are sophisticated eukaryotic parasites presenting a high level of genotypic variability the growth of the parasites in their host and that of cancer cells share at least one common feature, that is their mutual capacity for rapid cell division. Surprisingly, the parasitic diseases and cancers share some immune evasion strategies. Consideration of these immunological alterations must be added to the evaluation of the pathogenic processes. The molecular and functional characterization of virulence factors and the study of their effect on the arms of the immune system have greatly improved understanding of the regulation of immune effectors functions. The purpose of this review is to analyze some of the current data related to the regulatory components or processes originating from the parasite that control or interfere with host cell physiology. Attempts are also made to delineate some similarities between the immune evasion strategies that parasites and tumors employ. The elucidation of the mode of action of parasite virulence factors toward the host cell allow not only provide us with a more comprehensive view of the host-parasite relationships but may also represent a step forward in efforts aimed to identify new target molecules for therapeutic intervention.

  5. RNase MRP and the RNA processing cascade in the eukaryotic ancestor.

    Science.gov (United States)

    Woodhams, Michael D; Stadler, Peter F; Penny, David; Collins, Lesley J

    2007-02-08

    Within eukaryotes there is a complex cascade of RNA-based macromolecules that process other RNA molecules, especially mRNA, tRNA and rRNA. An example is RNase MRP processing ribosomal RNA (rRNA) in ribosome biogenesis. One hypothesis is that this complexity was present early in eukaryotic evolution; an alternative is that an initial simpler network later gained complexity by gene duplication in lineages that led to animals, fungi and plants. Recently there has been a rapid increase in support for the complexity-early theory because the vast majority of these RNA-processing reactions are found throughout eukaryotes, and thus were likely to be present in the last common ancestor of living eukaryotes, herein called the Eukaryotic Ancestor. We present an overview of the RNA processing cascade in the Eukaryotic Ancestor and investigate in particular, RNase MRP which was previously thought to have evolved later in eukaryotes due to its apparent limited distribution in fungi and animals and plants. Recent publications, as well as our own genomic searches, find previously unknown RNase MRP RNAs, indicating that RNase MRP has a wide distribution in eukaryotes. Combining secondary structure and promoter region analysis of RNAs for RNase MRP, along with analysis of the target substrate (rRNA), allows us to discuss this distribution in the light of eukaryotic evolution. We conclude that RNase MRP can now be placed in the RNA-processing cascade of the Eukaryotic Ancestor, highlighting the complexity of RNA-processing in early eukaryotes. Promoter analyses of MRP-RNA suggest that regulation of the critical processes of rRNA cleavage can vary, showing that even these key cellular processes (for which we expect high conservation) show some species-specific variability. We present our consensus MRP-RNA secondary structure as a useful model for further searches.

  6. The ecology of fish parasites with particular reference to helminth parasites and their salmonid fish hosts in Welsh rivers: a review of some of the central questions.

    Science.gov (United States)

    Thomas, J D

    2002-01-01

    was positively correlated with the condition factor and the adipose index. Two testable hypotheses were advanced to explain these observations. First, the more dominant well-conditioned fish in the hierarchy are more likely to acquire parasites because they ingest more food items and spend more time in sheltered habitats with depositing sediments where transmission mainly occurs. Second, the parasites may release factors that stimulate the host's immune and endocrinological systems to produce factors that enhance somatic growth and inhibit reproduction of the host. This benign relationship is considered to be indicative of long-term coevolution. The sex of the fish had a significant influence on the abundance of the parasites in total and also on particular species with the bias in all cases being in favour of the female fish. This review shows that sex bias in parasitism is generally not strong and that male bias in parasitism is not a general rule. Taken as a whole, the results fail to support most of the predictions based on the Hamilton-Zuk and the immunocompetence hypotheses. Possible hypotheses to explain why parasitism tends to be higher in female than in male trout include testosterone immunosuppression, corticosteroid-based immune suppression and differences between the size and behaviour of the sexes. However, the latter two hypotheses have more credence, although testosterone levels are higher in female than male trout. Between the early 1950s and 1998 there has been a marked decline in the prevalence, abundance and diversity of the helminth parasite communities in salmonid fish as well as their intermediate hosts. Possible reasons for these declines include heavy metal pollution, increased acidity and habitat degradation linked to changes in land use. It is concluded that although helminth parasites can provide supplementary information on pollution. the use of biotic indices based on the Biological monitoring working party (BMWP) or River invertebrate

  7. Can Parasites Really Reveal Environmental Impact?

    Science.gov (United States)

    This review assesses the usefulness of parasites as bioindicators of environmental impact. Relevant studies published in the past decade were compiled; factorial meta-analysis demonstrated significant effects and interactions between parasite levels and the presence and concentra...

  8. Parasitic Nematode Interactions with Mammals and Plants

    NARCIS (Netherlands)

    Jasmer, D.P.; Goverse, A.; Smant, G.

    2003-01-01

    Parasitic nematodes that infect humans, animals, and plants cause serious diseases that are deleterious to human health and agricultural productivity. Chemical and biological control methods have reduced the impact of these parasites. However, surviving environmental stages lead to persistent

  9. Everyday and Exotic Foodborne Parasites

    Directory of Open Access Journals (Sweden)

    Marilyn B Lee

    2000-01-01

    Full Text Available Everyday foodborne parasites, which are endemic in Canada, include the protozoans Entamoeba histolytica, Giardia lamblia and Cryptosporidium parvum. However, these parasites are most frequently acquired through unfiltered drinking water, homosexual activity or close personal contact such as in daycare centres and occasionally via a food vehicle. It is likely that many foodborne outbreaks from these protozoa go undetected. Transmission of helminth infections, such as tapeworms, is rare in Canada because of effective sewage treatment. However, a common foodborne parasite of significance is Toxoplasma gondii. Although infection can be acquired from accidental ingestion of oocysts from cat feces, infection can also result from consumption of tissue cysts in undercooked meat, such as pork or lamb. Congenital transmission poses an immense financial burden, costing Canada an estimated $240 million annually. Also of concern is toxoplasmosis in AIDS patients, which may lead to toxoplasmosis encephalitis, the second most common AIDS-related opportunistic infection of the central nervous system. Exotic parasites (ie, those acquired from abroad or from imported food are of growing concern because more Canadians are travelling and the number of Canada?s trading partners is increasing. Since 1996, over 3000 cases of Cyclospora infection reported in the United States and Canada were epidemiologically associated with importation of Guatemalan raspberries. Unlike toxoplasmosis, where strategies for control largely rest with individual practices, control of cyclosporiasis rests with government policy, which should prohibit the importation of foods at high risk.

  10. Energy parasites trigger oncogene mutation

    Czech Academy of Sciences Publication Activity Database

    Pokorný, Jiří; Pokorný, Jan; Jandová, Anna; Kobilková, J.; Vrba, J.; Vrba, J. jr.

    2016-01-01

    Roč. 92, č. 10 (2016), s. 577-582 ISSN 0955-3002 R&D Projects: GA ČR GA16-12757S Institutional support: RVO:68378271 ; RVO:67985882 Keywords : cancer initiation * cell-mediated immunity * coherent electromagnetic states * genome somatic mutation * LDH virus * parasitic energy consumption Subject RIV: BO - Biophysics Impact factor: 1.992, year: 2016

  11. Zoology: Invertebrates that Parasitize Invertebrates.

    Science.gov (United States)

    Giribet, Gonzalo

    2016-07-11

    The genome of an orthonectid, a group of highly modified parasitic invertebrates, is drastically reduced and compact, yet it shows the bilaterian gene toolkit. Phylogenetic analyses place the enigmatic orthonectids within Spiralia, although their exact placement remains uncertain. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Intestinal Parasites of the Grasscutter

    African Journals Online (AJOL)

    User

    excretions of carrier cane rats (Oboegbulem. & Okoronkwo, 1990). The possibility of transmission of parasites of the grasscutter to humans cannot be overlooked. This is more so as some people do not only cherish grasscutter meat but also use the content of the gut both for medicinal purposes and for food (pers. comm.).

  13. Fish immunity to scuticociliate parasites

    NARCIS (Netherlands)

    Piazzon de Haro, M.C.; Leiro, J.M.; Lamas, J.

    2013-01-01

    Some species of scuticociliates (Ciliophora) behave as facultative parasites and produce severe mortalities in cultured fish. Pathogenic scuticociliates can cause surface lesions and can also penetrate inside the body, where they feed on tissue and proliferate in the blood and most internal organs,

  14. Nuclear hormone receptors in parasitic helminths

    OpenAIRE

    Wu, Wenjie; LoVerde, Philip T

    2010-01-01

    Nuclear receptors (NRs) belong to a large protein superfamily that are important transcriptional modulators in metazoans. Parasitic helminths include parasitic worms from the Lophotrochozoa (Platyhelminths) and Ecdysozoa (Nematoda). NRs in parasitic helminths diverged into two different evolutionary lineages. NRs in parasitic Platyhelminths have orthologues in Deuterostomes, in arthropods or both with a feature of extensive gene loss and gene duplication within different gene groups. NRs in p...

  15. Eukaryotic translation initiation factor 5A of wheat: Identification ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-05-18

    . The available literature indi- cated that the expression of eIF5A was temporal and spatial difference and suppressing eIF5A activation causes pleiotropic effects. Transcript analysis reveals that two tobacco eIF5A genes ...

  16. Fishing drives declines in fish parasite diversity and has variable effects on parasite abundance.

    Science.gov (United States)

    Wood, Chelsea L; Sandin, Stuart A; Zgliczynski, Brian; Guerra, Ana Sofía; Micheli, Fiorenza

    2014-07-01

    Despite the ubiquity and ecological importance of parasites, relatively few studies have assessed their response to anthropogenic environmental change. Heuristic models have predicted both increases and decreases in parasite abundance in response to human disturbance, with empirical support for both. However, most studies focus on one or a few selected parasite species. Here, we assess the abundance of parasites of seven species of coral reef fishes collected from three fished and three unfished islands of the Line Islands archipelago in the central equatorial Pacific. Because we chose fish hosts that spanned different trophic levels, taxonomic groups, and body sizes, we were able to compare parasite responses across a broad cross section of the total parasite community in the presence and absence of fishing, a major human impact on marine ecosystems. We found that overall parasite species richness was substantially depressed on fished islands, but that the response of parasite abundance varied among parasite taxa: directly transmitted parasites were significantly more abundant on fished than on unfished islands, while the reverse was true for trophically transmitted parasites. This probably arises because trophically transmitted parasites require multiple host species, some of which are the top predators most sensitive to fishing impacts. The increase in directly transmitted parasites appeared to be due to fishing-driven compensatory increases in the abundance of their hosts. Together, these results provide support for the predictions of both heuristic models, and indicate that the direction of fishing's impact on parasite abundance is mediated by parasite traits, notably parasite transmission strategies.

  17. Parasites as prey in aquatic food webs: implications for predator infection and parasite transmission

    NARCIS (Netherlands)

    Thieltges, D.W.; Amundsen, P.-A.; Hechinger, R.F.; Johnson, P.T.J.; Lafferty, K.D.; Mouritsen, K.N.; Preston, D.L.; Reise, K.; Zander, C.D.; Poulin, R.

    2013-01-01

    While the recent inclusion of parasites into food-web studies has highlighted the role of parasites as consumers, there is accumulating evidence that parasites can also serve as prey for predators. Here we investigated empirical patterns of predation on parasites and their relationships with

  18. Parasites of mammals species abundance near zone Chernobyl

    International Nuclear Information System (INIS)

    Pen'kevich, V.A.

    2014-01-01

    In wildlife reserve parasitize various types of parasites: arachnids (mites) parasitic insects (horseflies, keds, mosquitoes, gnats, midges), helminths (trematodes, cestodes, nematodes and acanthocephalans) and parasitic protozoa. In quantity: 3 (beaver) to 25 species (wolf). (authors)

  19. Quantitative Analysis of a Parasitic Antiviral Strategy

    OpenAIRE

    Kim, Hwijin; Yin, John

    2004-01-01

    We extended a computer simulation of viral intracellular growth to study a parasitic antiviral strategy that diverts the viral replicase toward parasite growth. This strategy inhibited virus growth over a wide range of conditions, while minimizing host cell perturbations. Such parasitic strategies may inhibit the development of drug-resistant virus strains.

  20. 9 CFR 381.88 - Parasites.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Parasites. 381.88 Section 381.88 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE AGENCY... § 381.88 Parasites. Organs or other parts of carcasses which are found to be infested with parasites, or...

  1. New Laboulbeniales parasitic on endogean ground beetles.

    Science.gov (United States)

    Rossi, Walter; Santamaria, Sergi

    2008-01-01

    Three new species of Laboulbenia occurring on endogean Carabidae are described. These are L. lucifuga, parasitic on Winklerites spp. from Greece, L. magrinii, parasitic on Typloreicheia spp. from Italy, Reicheia spp. from Italy and Corsica and L. vailatii, parasitic on Coecoparvus spp. from Greece. New characters of L. coiffatii and L. endogea are pointed out, and the genus Scalenomyces is synonymized with Laboulbenia.

  2. What can we infer about the origin of sex in early eukaryotes?

    NARCIS (Netherlands)

    Speijer, Dave

    2016-01-01

    Current analysis shows that the last eukaryotic common ancestor (LECA) was capable of full meiotic sex. The original eukaryotic life cycle can probably be described as clonal, interrupted by episodic sex triggered by external or internal stressors. The cycle could have started in a highly flexible

  3. Sex is a ubiquitous, ancient, and inherent attribute of eukaryotic life

    NARCIS (Netherlands)

    Speijer, Dave; Lukeš, Julius; Eliáš, Marek

    2015-01-01

    Sexual reproduction and clonality in eukaryotes are mostly seen as exclusive, the latter being rather exceptional. This view might be biased by focusing almost exclusively on metazoans. We analyze and discuss reproduction in the context of extant eukaryotic diversity, paying special attention to

  4. Genome-wide Purification of Extrachromosomal Circular DNA from Eukaryotic Cells

    DEFF Research Database (Denmark)

    Møller, Henrik D.; Bojsen, Rasmus Kenneth; Tachibana, Chris

    2016-01-01

    Extrachromosomal circular DNAs (eccDNAs) are common genetic elements in Saccharomyces cerevisiae and are reported in other eukaryotes as well. EccDNAs contribute to genetic variation among somatic cells in multicellular organisms and to evolution of unicellular eukaryotes. Sensitive methods for d...

  5. Eelgrass Leaf Surface Microbiomes Are Locally Variable and Highly Correlated with Epibiotic Eukaryotes

    Directory of Open Access Journals (Sweden)

    Mia M. Bengtsson

    2017-07-01

    Full Text Available Eelgrass (Zostera marina is a marine foundation species essential for coastal ecosystem services around the northern hemisphere. Like all macroscopic organisms, it possesses a microbiome (here defined as an associated prokaryotic community which may play critical roles in modulating the interaction of eelgrass with its environment. For example, its leaf surface microbiome could inhibit or attract eukaryotic epibionts which may overgrow the eelgrass leading to reduced primary productivity and subsequent eelgrass meadow decline. We used amplicon sequencing of the 16S and 18S rRNA genes of prokaryotes and eukaryotes to assess the leaf surface microbiome (prokaryotes as well as eukaryotic epibionts in- and outside lagoons on the German Baltic Sea coast. Prokaryote microbiomes varied substantially both between sites inside lagoons and between open coastal and lagoon sites. Water depth, leaf area and biofilm chlorophyll a concentration explained a large amount of variation in both prokaryotic and eukaryotic community composition. The prokaryotic microbiome and eukaryotic epibiont communities were highly correlated, and network analysis revealed disproportionate co-occurrence between a limited number of eukaryotic taxa and several bacterial taxa. This suggests that eelgrass leaf surfaces are home to a mosaic of microbiomes of several epibiotic eukaryotes, in addition to the microbiome of the eelgrass itself. Our findings thereby underline that eukaryotic diversity should be taken into account in order to explain prokaryotic microbiome assembly and dynamics in aquatic environments.

  6. Use of prokaryotic transcriptional activators as metabolite biosensors in eukaryotic cells

    DEFF Research Database (Denmark)

    2018-01-01

    The present invention relates to the use of transcriptional activators from prokaryotic organisms for use in eukaryotic cells, such as yeast as sensors of intracellular and extracellular accumulation of a ligand or metabolite specifically activating this transcriptional activator in a eukaryot...

  7. Genome-wide Purification of Extrachromosomal Circular DNA from Eukaryotic Cells

    DEFF Research Database (Denmark)

    Møller, Henrik D.; Bojsen, Rasmus Kenneth; Tachibana, Chris

    2016-01-01

    Extrachromosomal circular DNAs (eccDNAs) are common genetic elements in Saccharomyces cerevisiae and are reported in other eukaryotes as well. EccDNAs contribute to genetic variation among somatic cells in multicellular organisms and to evolution of unicellular eukaryotes. Sensitive methods...

  8. Transcriptionally Driven DNA Replication Program of the Human Parasite Leishmania major.

    Science.gov (United States)

    Lombraña, Rodrigo; Álvarez, Alba; Fernández-Justel, José Miguel; Almeida, Ricardo; Poza-Carrión, César; Gomes, Fábia; Calzada, Arturo; Requena, José María; Gómez, María

    2016-08-09

    Faithful inheritance of eukaryotic genomes requires the orchestrated activation of multiple DNA replication origins (ORIs). Although origin firing is mechanistically conserved, how origins are specified and selected for activation varies across different model systems. Here, we provide a complete analysis of the nucleosomal landscape and replication program of the human parasite Leishmania major, building on a better evolutionary understanding of replication organization in Eukarya. We found that active transcription is a driving force for the nucleosomal organization of the L. major genome and that both the spatial and the temporal program of DNA replication can be explained as associated to RNA polymerase kinetics. This simple scenario likely provides flexibility and robustness to deal with the environmental changes that impose alterations in the genetic programs during parasitic life cycle stages. Our findings also suggest that coupling replication initiation to transcription elongation could be an ancient solution used by eukaryotic cells for origin maintenance. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

  9. Insect antimicrobial peptides act synergistically to inhibit a trypanosome parasite.

    Science.gov (United States)

    Marxer, Monika; Vollenweider, Vera; Schmid-Hempel, Paul

    2016-05-26

    The innate immune system provides protection from infection by producing essential effector molecules, such as antimicrobial peptides (AMPs) that possess broad-spectrum activity. This is also the case for bumblebees, Bombus terrestris, when infected by the trypanosome, Crithidia bombi Furthermore, the expressed mixture of AMPs varies with host genetic background and infecting parasite strain (genotype). Here, we used the fact that clones of C. bombi can be cultivated and kept as strains in medium to test the effect of various combinations of AMPs on the growth rate of the parasite. In particular, we used pairwise combinations and a range of physiological concentrations of three AMPs, namely Abaecin, Defensin and Hymenoptaecin, synthetized from the respective genomic sequences. We found that these AMPs indeed suppress the growth of eight different strains of C. bombi, and that combinations of AMPs were typically more effective than the use of a single AMP alone. Furthermore, the most effective combinations were rarely those consisting of maximum concentrations. In addition, the AMP combination treatments revealed parasite strain specificity, such that strains varied in their sensitivity towards the same mixtures. Hence, variable expression of AMPs could be an alternative strategy to combat highly variable infections.This article is part of the themed issue 'Evolutionary ecology of arthropod antimicrobial peptides'. © 2016 The Author(s).

  10. Comparative genomic analysis of multi-subunit tethering complexes demonstrates an ancient pan-eukaryotic complement and sculpting in Apicomplexa.

    Directory of Open Access Journals (Sweden)

    Christen M Klinger

    Full Text Available Apicomplexa are obligate intracellular parasites that cause tremendous disease burden world-wide. They utilize a set of specialized secretory organelles in their invasive process that require delivery of components for their biogenesis and function, yet the precise mechanisms underpinning such processes remain unclear. One set of potentially important components is the multi-subunit tethering complexes (MTCs, factors increasingly implicated in all aspects of vesicle-target interactions. Prompted by the results of previous studies indicating a loss of membrane trafficking factors in Apicomplexa, we undertook a bioinformatic analysis of MTC conservation. Building on knowledge of the ancient presence of most MTC proteins, we demonstrate the near complete retention of MTCs in the newly available genomes for Guillardiatheta and Bigelowiellanatans. The latter is a key taxonomic sampling point as a basal sister taxa to the group including Apicomplexa. We also demonstrate an ancient origin of the CORVET complex subunits Vps8 and Vps3, as well as the TRAPPII subunit Tca17. Having established that the lineage leading to Apicomplexa did at one point possess the complete eukaryotic complement of MTC components, we undertook a deeper taxonomic investigation in twelve apicomplexan genomes. We observed excellent conservation of the VpsC core of the HOPS and CORVET complexes, as well as the core TRAPP subunits, but sparse conservation of TRAPPII, COG, Dsl1, and HOPS/CORVET-specific subunits. However, those subunits that we did identify appear to be expressed with similar patterns to the fully conserved MTC proteins, suggesting that they may function as minimal complexes or with analogous partners. Strikingly, we failed to identify any subunits of the exocyst complex in all twelve apicomplexan genomes, as well as the dinoflagellate Perkinsus marinus. Overall, we demonstrate reduction of MTCs in Apicomplexa and their ancestors, consistent with modification during

  11. On the Archaeal Origins of Eukaryotes and the Challenges of Inferring Phenotype from Genotype.

    Science.gov (United States)

    Dey, Gautam; Thattai, Mukund; Baum, Buzz

    2016-07-01

    If eukaryotes arose through a merger between archaea and bacteria, what did the first true eukaryotic cell look like? A major step toward an answer came with the discovery of Lokiarchaeum, an archaeon whose genome encodes small GTPases related to those used by eukaryotes to regulate membrane traffic. Although 'Loki' cells have yet to be seen, their existence has prompted the suggestion that the archaeal ancestor of eukaryotes engulfed the future mitochondrion by phagocytosis. We propose instead that the archaeal ancestor was a relatively simple cell, and that eukaryotic cellular organization arose as the result of a gradual transfer of bacterial genes and membranes driven by an ever-closer symbiotic partnership between a bacterium and an archaeon. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  12. Engineering a palette of eukaryotic chromoproteins for bacterial synthetic biology.

    Science.gov (United States)

    Liljeruhm, Josefine; Funk, Saskia K; Tietscher, Sandra; Edlund, Anders D; Jamal, Sabri; Wistrand-Yuen, Pikkei; Dyrhage, Karl; Gynnå, Arvid; Ivermark, Katarina; Lövgren, Jessica; Törnblom, Viktor; Virtanen, Anders; Lundin, Erik R; Wistrand-Yuen, Erik; Forster, Anthony C

    2018-01-01

    Coral reefs are colored by eukaryotic chromoproteins (CPs) that are homologous to green fluorescent protein. CPs differ from fluorescent proteins (FPs) by intensely absorbing visible light to give strong colors in ambient light. This endows CPs with certain advantages over FPs, such as instrument-free detection uncomplicated by ultra-violet light damage or background fluorescence, efficient Förster resonance energy transfer (FRET) quenching, and photoacoustic imaging. Thus, CPs have found utility as genetic markers and in teaching, and are attractive for potential cell biosensor applications in the field. Most near-term applications of CPs require expression in a different domain of life: bacteria. However, it is unclear which of the eukaryotic CP genes might be suitable and how best to assay them. Here, taking advantage of codon optimization programs in 12 cases, we engineered 14 CP sequences (meffRed, eforRed, asPink, spisPink, scOrange, fwYellow, amilGFP, amajLime, cjBlue, meffBlue, aeBlue, amilCP, tsPurple and gfasPurple) into a palette of Escherichia coli BioBrick plasmids. BioBricks comply with synthetic biology's most widely used, simplified, cloning standard. Differences in color intensities, maturation times and fitness costs of expression were compared under the same conditions, and visible readout of gene expression was quantitated. A surprisingly large variation in cellular fitness costs was found, resulting in loss of color in some overnight liquid cultures of certain high-copy-plasmid-borne CPs, and cautioning the use of multiple CPs as markers in competition assays. We solved these two problems by integrating pairs of these genes into the chromosome and by engineering versions of the same CP with very different colors. Availability of 14 engineered CP genes compared in E. coli , together with chromosomal mutants suitable for competition assays, should simplify and expand CP study and applications. There was no single plasmid-borne CP that combined

  13. Sodium fire suppression

    Energy Technology Data Exchange (ETDEWEB)

    Malet, J C [DSN/SESTR, Centre de Cadarache, Saint-Paul-lez-Durance (France)

    1979-03-01

    Ignition and combustion studies have provided valuable data and guidelines for sodium fire suppression research. The primary necessity is to isolate the oxidant from the fuel, rather than to attempt to cool the sodium below its ignition temperature. Work along these lines has led to the development of smothering tank systems and a dry extinguishing powder. Based on the results obtained, the implementation of these techniques is discussed with regard to sodium fire suppression in the Super-Phenix reactor. (author)

  14. Sodium fire suppression

    International Nuclear Information System (INIS)

    Malet, J.C.

    1979-01-01

    Ignition and combustion studies have provided valuable data and guidelines for sodium fire suppression research. The primary necessity is to isolate the oxidant from the fuel, rather than to attempt to cool the sodium below its ignition temperature. Work along these lines has led to the development of smothering tank systems and a dry extinguishing powder. Based on the results obtained, the implementation of these techniques is discussed with regard to sodium fire suppression in the Super-Phenix reactor. (author)

  15. Diagnostic problems with parasitic and non-parasitic splenic cysts

    Directory of Open Access Journals (Sweden)

    Adas Gokhan

    2009-05-01

    Full Text Available Abstract Background The splenic cysts constitute a very rare clinical entity. They may occur secondary to trauma or even being more seldom due to parasitic infestations, mainly caused by ecchinocccus granulosus. Literature lacks a defined concencus including the treatment plans and follow up strategies, nor long term results of the patients. In the current study, we aimed to evaluate the diagnosis, management of patients with parasitic and non-parasitic splenic cysts together with their long term follow up progresses. Methods Twenty-four patients with splenic cysts have undergone surgery in our department over the last 9 years. Data from eighteen of the twenty-four patients were collected prospectively, while data from six were retrospectively collected. All patients were assessed in terms of age, gender, hospital stay, preoperative diagnosis, additional disease, serology, ultrasonography, computed tomography (CT, cyst recurrences and treatment. Results In this study, the majority of patients presented with abdominal discomfort and palpable swelling in the left hypochondrium. All patients were operated on electively. The patients included 14 female and 10 male patients, with a mean age of 44.77 years (range 20–62. Splenic hydatid cysts were present in 16 patients, one of whom also had liver hydatid cysts (6.25%. Four other patients were operated on for a simple cyst (16% two patients for an epithelial cyst, and the last two for splenic lymphangioma. Of the 16 patients diagnosed as having splenic hydatit cysts, 11 (68.7% were correctly diagnosed. Only two of these patients were administered benzimidazole therapy pre-operatively because of the risk of multicystic disease The mean follow-up period was 64 months (6–108. There were no recurrences of splenic cysts. Conclusion Surgeons should keep in mind the possibility of a parasitic cyst when no definitive alternative diagnosis can be made. In the treatment of splenic hydatidosis, benzimidazole

  16. Nuclear techniques in the study of parasitic infections

    International Nuclear Information System (INIS)

    1982-01-01

    Out of 57 papers published, 47 fall within the INIS subject scope. Seven main topics were covered: resistance to infections with protozoan parasites; resistance to infections with African trypanosomes and helminths of ruminant animals; resistance to infections with filarial parasites and schistosomes; pathology of parasitic infections; epidemiology and diagnosis of parasitic infections; physiology and biochemistry of parasitic organisms; pharmacodynamics of anti-parasitic agents

  17. Smart Parasitic Nematodes Use Multifaceted Strategies to Parasitize Plants

    Directory of Open Access Journals (Sweden)

    Muhammad A. Ali

    2017-10-01

    Full Text Available Nematodes are omnipresent in nature including many species which are parasitic to plants and cause enormous economic losses in various crops. During the process of parasitism, sedentary phytonematodes use their stylet to secrete effector proteins into the plant cells to induce the development of specialized feeding structures. These effectors are used by the nematodes to develop compatible interactions with plants, partly by mimicking the expression of host genes. Intensive research is going on to investigate the molecular function of these effector proteins in the plants. In this review, we have summarized which physiological and molecular changes occur when endoparasitic nematodes invade the plant roots and how they develop a successful interaction with plants using the effector proteins. We have also mentioned the host genes which are induced by the nematodes for a compatible interaction. Additionally, we discuss how nematodes modulate the reactive oxygen species (ROS and RNA silencing pathways in addition to post-translational modifications in their own favor for successful parasitism in plants.

  18. Parasitic infections of the external eye.

    Science.gov (United States)

    Pahuja, Shivani; Puranik, Charuta; Jelliti, Bechir; Khairallah, Moncef; Sangwan, Virender S

    2013-08-01

    To review the published literature on parasitic infections of external eye. Published articles and case reports on parasitic infections of external eye were reviewed and relevant information was collected. Parasitic infections of the eye are rare. However, being more commonly seen in developing nations, they require active measures for screening, diagnosis, and therapy. Parasites of importance causing external ocular disease are protozoan parasites, such as Leishmania; metazoans, such as nematodes (roundworms), cestodes (tapeworms), and trematodes (flatworms); or ectoparasites, such as Phthirus pubis and Demodex.

  19. RNA Interference: A Novel Source of Resistance to Combat Plant Parasitic Nematodes

    Directory of Open Access Journals (Sweden)

    Sagar Banerjee

    2017-05-01

    Full Text Available Plant parasitic nematodes cause severe damage and yield loss in major crops all over the world. Available control strategies include use of insecticides/nematicides but these have proved detrimental to the environment, while other strategies like crop rotation and resistant cultivars have serious limitations. This scenario provides an opportunity for the utilization of technological advances like RNA interference (RNAi to engineer resistance against these devastating parasites. First demonstrated in the model free living nematode, Caenorhabtidis elegans; the phenomenon of RNAi has been successfully used to suppress essential genes of plant parasitic nematodes involved in parasitism, nematode development and mRNA metabolism. Synthetic neurotransmitants mixed with dsRNA solutions are used for in vitro RNAi in plant parasitic nematodes with significant success. However, host delivered in planta RNAi has proved to be a pioneering phenomenon to deliver dsRNAs to feeding nematodes and silence the target genes to achieve resistance. Highly enriched genomic databases are exploited to limit off target effects and ensure sequence specific silencing. Technological advances like gene stacking and use of nematode inducible and tissue specific promoters can further enhance the utility of RNAi based transgenics against plant parasitic nematodes.

  20. Experimental Infection and Clearance of Coccidian Parasites in Mercury-Exposed Zebra Finches.

    Science.gov (United States)

    Ebers Smith, Jessica H; Cristol, Daniel A; Swaddle, John P

    2018-01-01

    Mercury is a globally distributed, persistent environmental contaminant that affects the health of many taxa. It can suppress the immune system, which often plays a role in defense against parasites. However, there have been few investigations of whether mercury affects the abilities of animals to resist parasitic infection. Here, we exposed zebra finches to a lifetime dietary exposure of methylmercury (1.2 μg/g wet weight) and experimentally infected them with coccidian parasites to examine the effect of methylmercury exposure on parasitic infection. The mercury-exposed birds did not have an altered immune response (heterophil:lymphocyte ratio) nor a reduced ability to clear the infection. However, mercury-exposed birds tended to have higher parasite loads at the time when we expected the greatest immune response (2-3 weeks post-infection). Although mercury did not greatly influence the infection-course of this parasite in captivity, responses may be more accentuated in the wild where birds face additional immune challenges.

  1. Relevance of intracellular polarity to accuracy of eukaryotic chemotaxis

    International Nuclear Information System (INIS)

    Hiraiwa, Tetsuya; Nishikawa, Masatoshi; Shibata, Tatsuo; Nagamatsu, Akihiro; Akuzawa, Naohiro

    2014-01-01

    Eukaryotic chemotaxis is usually mediated by intracellular signals that tend to localize at the front or back of the cell. Such intracellular polarities frequently require no extracellular guidance cues, indicating that spontaneous polarization occurs in the signal network. Spontaneous polarization activity is considered relevant to the persistent motions in random cell migrations and chemotaxis. In this study, we propose a theoretical model that connects spontaneous intracellular polarity and motile ability in a chemoattractant solution. We demonstrate that the intracellular polarity can enhance the accuracy of chemotaxis. Chemotactic accuracy should also depend on chemoattractant concentration through the concentration-dependent correlation time in the polarity direction. Both the polarity correlation time and the chemotactic accuracy depend on the degree of responsiveness to the chemical gradient. We show that optimally accurate chemotaxis occurs at an intermediate responsiveness of intracellular polarity. Experimentally, we find that the persistence time of randomly migrating Dictyostelium cells depends on the chemoattractant concentration, as predicted by our theory. At the optimum responsiveness, this ameboid cell can enhance its chemotactic accuracy tenfold. (paper)

  2. NMR comparison of prokaryotic and eukaryotic cytochromes c

    International Nuclear Information System (INIS)

    Chau, Meihing; Cai, Meng Li; Timkovich, R.

    1990-01-01

    1 H NMR spectroscopy has been used to examine ferrocytochrome c-551 from Pseudomonas aeruginosa (ATCC 19429) over the pH range 3.5-10.6 and the temperature range 4-60 degree C. Resonance assignments are proposed for main-chain and side-chain protons. Comparison of results for cytochrome c-551 to recently assigned spectra for horse cytochrome c and mutants of yeast iso-1 cytochrome reveals some unique resonances with unusual chemical shifts in all cytochromes that may serve as markers for the heme region. Results for cytochrome c-551 indicate that in the smaller prokaryotic cytochrome, all benzoid side chains are rapidly flipping on the NMR time scale. In contrast, in eukaryotic cytochromes there are some rings flipping slowly on the NMR time scale. The ferrocytochrome c-551 undergoes a transition linked to pH with a pK around 7. The pH behavior of assigned resonances provides evidence that the site of protonation is the inner or buried 17-propionic acid heme substituent (IUPAC-IUB porphyrin nomenclature). Conformational heterogeneity has been observed for segments near the inner heme propionate substituent

  3. Structural similarities between prokaryotic and eukaryotic 5S ribosomal RNAs

    International Nuclear Information System (INIS)

    Welfle, H.; Boehm, S.; Damaschun, G.; Fabian, H.; Gast, K.; Misselwitz, R.; Mueller, J.J.; Zirwer, D.; Filimonov, V.V.; Venyaminov, S.Yu.; Zalkova, T.N.

    1986-01-01

    5S RNAs from rat liver and E. coli have been studied by diffuse X-ray and dynamic light scattering and by infrared and Raman spectroscopy. Identical structures at a resolution of 1 nm can be deduced from the comparison of the experimental X-ray scattering curves and electron distance distribution functions and from the agreement of the shape parameters. A flat shape model with a compact central region and two protruding arms was derived. Double helical stems are eleven-fold helices with a mean base pair distance of 0.28 nm. The number of base pairs (26 GC, 9 AU for E. coli; 27 GC, 9 AU for rat liver) and the degree of base stacking are the same within the experimental error. A very high regularity in the ribophosphate backbone is indicated for both 5S RNAs. The observed structural similarity and the consensus secondary structure pattern derived from comparative sequence analyses suggest the conclusion that prokaryotic and eukaryotic 5S RNAs are in general very similar with respect to their fundamental structural features. (author)

  4. Biosurfactant gene clusters in eukaryotes: regulation and biotechnological potential.

    Science.gov (United States)

    Roelants, Sophie L K W; De Maeseneire, Sofie L; Ciesielska, Katarzyna; Van Bogaert, Inge N A; Soetaert, Wim

    2014-04-01

    Biosurfactants (BSs) are a class of secondary metabolites representing a wide variety of structures that can be produced from renewable feedstock by a wide variety of micro-organisms. They have (potential) applications in the medical world, personal care sector, mining processes, food industry, cosmetics, crop protection, pharmaceuticals, bio-remediation, household detergents, paper and pulp industry, textiles, paint industries, etc. Especially glycolipid BSs like sophorolipids (SLs), rhamnolipids (RLs), mannosylerythritol lipids (MELs) and cellobioselipids (CBLs) have been described to provide significant opportunities to (partially) replace chemical surfactants. The major two factors currently limiting the penetration of BSs into the market are firstly the limited structural variety and secondly the rather high production price linked with the productivity. One of the keys to resolve the above mentioned bottlenecks can be found in the genetic engineering of natural producers. This could not only result in more efficient (economical) recombinant producers, but also in a diversification of the spectrum of available BSs as such resolving both limiting factors at once. Unraveling the genetics behind the biosynthesis of these interesting biological compounds is indispensable for the tinkering, fine tuning and rearrangement of these biological pathways with the aim of obtaining higher yields and a more extensive structural variety. Therefore, this review focuses on recent developments in the investigation of the biosynthesis, genetics and regulation of some important members of the family of the eukaryotic glycolipid BSs (MELs, CBLs and SLs). Moreover, recent biotechnological achievements and the industrial potential of engineered strains are discussed.

  5. MCM Paradox: Abundance of Eukaryotic Replicative Helicases and Genomic Integrity.

    Science.gov (United States)

    Das, Mitali; Singh, Sunita; Pradhan, Satyajit; Narayan, Gopeshwar

    2014-01-01

    As a crucial component of DNA replication licensing system, minichromosome maintenance (MCM) 2-7 complex acts as the eukaryotic DNA replicative helicase. The six related MCM proteins form a heterohexamer and bind with ORC, CDC6, and Cdt1 to form the prereplication complex. Although the MCMs are well known as replicative helicases, their overabundance and distribution patterns on chromatin present a paradox called the "MCM paradox." Several approaches had been taken to solve the MCM paradox and describe the purpose of excess MCMs distributed beyond the replication origins. Alternative functions of these MCMs rather than a helicase had also been proposed. This review focuses on several models and concepts generated to solve the MCM paradox coinciding with their helicase function and provides insight into the concept that excess MCMs are meant for licensing dormant origins as a backup during replication stress. Finally, we extend our view towards the effect of alteration of MCM level. Though an excess MCM constituent is needed for normal cells to withstand stress, there must be a delineation of the threshold level in normal and malignant cells. This review also outlooks the future prospects to better understand the MCM biology.

  6. The prokaryote-eukaryote dichotomy: meanings and mythology.

    Science.gov (United States)

    Sapp, Jan

    2005-06-01

    Drawing on documents both published and archival, this paper explains how the prokaryote-eukaryote dichotomy of the 1960s was constructed, the purposes it served, and what it implied in terms of classification and phylogeny. In doing so, I first show how the concept was attributed to Edouard Chatton and the context in which he introduced the terms. Following, I examine the context in which the terms were reintroduced into biology in 1962 by Roger Stanier and C. B. van Niel. I study the discourse over the subsequent decade to understand how the organizational dichotomy took on the form of a natural classification as the kingdom Monera or superkingdom Procaryotae. Stanier and van Niel admitted that, in regard to constructing a natural classification of bacteria, structural characteristics were no more useful than physiological properties. They repeatedly denied that bacterial phylogenetics was possible. I thus examine the great historical irony that the "prokaryote," in both its organizational and phylogenetic senses, was defined (negatively) on the basis of structure. Finally, we see how phylogenetic research based on 16S rRNA led by Carl Woese and his collaborators confronted the prokaryote concept while moving microbiology to the center of evolutionary biology.

  7. The current state of eukaryotic DNA base damage and repair.

    Science.gov (United States)

    Bauer, Nicholas C; Corbett, Anita H; Doetsch, Paul W

    2015-12-02

    DNA damage is a natural hazard of life. The most common DNA lesions are base, sugar, and single-strand break damage resulting from oxidation, alkylation, deamination, and spontaneous hydrolysis. If left unrepaired, such lesions can become fixed in the genome as permanent mutations. Thus, evolution has led to the creation of several highly conserved, partially redundant pathways to repair or mitigate the effects of DNA base damage. The biochemical mechanisms of these pathways have been well characterized and the impact of this work was recently highlighted by the selection of Tomas Lindahl, Aziz Sancar and Paul Modrich as the recipients of the 2015 Nobel Prize in Chemistry for their seminal work in defining DNA repair pathways. However, how these repair pathways are regulated and interconnected is still being elucidated. This review focuses on the classical base excision repair and strand incision pathways in eukaryotes, considering both Saccharomyces cerevisiae and humans, and extends to some important questions and challenges facing the field of DNA base damage repair. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

  8. Susceptibilities to DNA Structural Transitions within Eukaryotic Genomes

    Science.gov (United States)

    Zhabinskaya, Dina; Benham, Craig; Madden, Sally

    2012-02-01

    We analyze the competitive transitions to alternate secondary DNA structures in a negatively supercoiled DNA molecule of kilobase length and specified base sequence. We use statistical mechanics to calculate the competition among all regions within the sequence that are susceptible to transitions to alternate structures. We use an approximate numerical method since the calculation of an exact partition function is numerically cumbersome for DNA molecules of lengths longer than hundreds of base pairs. This method yields accurate results in reasonable computational times. We implement algorithms that calculate the competition between transitions to denatured states and to Z-form DNA. We analyze these transitions near the transcription start sites (TSS) of a set of eukaryotic genes. We find an enhancement of Z-forming regions upstream of the TSS and a depletion of denatured regions around the start sites. We confirm that these finding are statistically significant by comparing our results to a set of randomized genes with preserved base composition at each position relative to the gene start sites. When we study the correlation of these transitions in orthologous mouse and human genes we find a clear evolutionary conservation of both types of transitions around the TSS.

  9. Isoprenoid biosynthesis in eukaryotic phototrophs: A spotlight on algae

    Energy Technology Data Exchange (ETDEWEB)

    Lohr M.; Schwender J.; Polle, J. E. W.

    2012-04-01

    Isoprenoids are one of the largest groups of natural compounds and have a variety of important functions in the primary metabolism of land plants and algae. In recent years, our understanding of the numerous facets of isoprenoid metabolism in land plants has been rapidly increasing, while knowledge on the metabolic network of isoprenoids in algae still lags behind. Here, current views on the biochemistry and genetics of the core isoprenoid metabolism in land plants and in the major algal phyla are compared and some of the most pressing open questions are highlighted. Based on the different evolutionary histories of the various groups of eukaryotic phototrophs, we discuss the distribution and regulation of the mevalonate (MVA) and the methylerythritol phosphate (MEP) pathways in land plants and algae and the potential consequences of the loss of the MVA pathway in groups such as the green algae. For the prenyltransferases, serving as gatekeepers to the various branches of terpenoid biosynthesis in land plants and algae, we explore the minimal inventory necessary for the formation of primary isoprenoids and present a preliminary analysis of their occurrence and phylogeny in algae with primary and secondary plastids. The review concludes with some perspectives on genetic engineering of the isoprenoid metabolism in algae.

  10. Specificity and evolvability in eukaryotic protein interaction networks.

    Directory of Open Access Journals (Sweden)

    Pedro Beltrao

    2007-02-01

    Full Text Available Progress in uncovering the protein interaction networks of several species has led to questions of what underlying principles might govern their organization. Few studies have tried to determine the impact of protein interaction network evolution on the observed physiological differences between species. Using comparative genomics and structural information, we show here that eukaryotic species have rewired their interactomes at a fast rate of approximately 10(-5 interactions changed per protein pair, per million years of divergence. For Homo sapiens this corresponds to 10(3 interactions changed per million years. Additionally we find that the specificity of binding strongly determines the interaction turnover and that different biological processes show significantly different link dynamics. In particular, human proteins involved in immune response, transport, and establishment of localization show signs of positive selection for change of interactions. Our analysis suggests that a small degree of molecular divergence can give rise to important changes at the network level. We propose that the power law distribution observed in protein interaction networks could be partly explained by the cell's requirement for different degrees of protein binding specificity.

  11. Classification and Lineage Tracing of SH2 Domains Throughout Eukaryotes.

    Science.gov (United States)

    Liu, Bernard A

    2017-01-01

    Today there exists a rapidly expanding number of sequenced genomes. Cataloging protein interaction domains such as the Src Homology 2 (SH2) domain across these various genomes can be accomplished with ease due to existing algorithms and predictions models. An evolutionary analysis of SH2 domains provides a step towards understanding how SH2 proteins integrated with existing signaling networks to position phosphotyrosine signaling as a crucial driver of robust cellular communication networks in metazoans. However organizing and tracing SH2 domain across organisms and understanding their evolutionary trajectory remains a challenge. This chapter describes several methodologies towards analyzing the evolutionary trajectory of SH2 domains including a global SH2 domain classification system, which facilitates annotation of new SH2 sequences essential for tracing the lineage of SH2 domains throughout eukaryote evolution. This classification utilizes a combination of sequence homology, protein domain architecture and the boundary positions between introns and exons within the SH2 domain or genes encoding these domains. Discrete SH2 families can then be traced across various genomes to provide insight into its origins. Furthermore, additional methods for examining potential mechanisms for divergence of SH2 domains from structural changes to alterations in the protein domain content and genome duplication will be discussed. Therefore a better understanding of SH2 domain evolution may enhance our insight into the emergence of phosphotyrosine signaling and the expansion of protein interaction domains.

  12. Discrepancy variation of dinucleotide microsatellite repeats in eukaryotic genomes

    Directory of Open Access Journals (Sweden)

    HUAN GAO

    2009-01-01

    Full Text Available To address whether there are differences of variation among repeat motif types and among taxonomic groups, we present here an analysis of variation and correlation of dinucleotide microsatellite repeats in eukaryotic genomes. Ten taxonomic groups were compared, those being primates, mammalia (excluding primates and rodentia, rodentia, birds, fish, amphibians and reptiles, insects, molluscs, plants and fungi, respectively. The data used in the analysis is from the literature published in the Journal of Molecular Ecology Notes. Analysis of variation reveals that there are no significant differences between AC and AG repeat motif types. Moreover, the number of alleles correlates positively with the copy number in both AG and AC repeats. Similar conclusions can be obtained from each taxonomic group. These results strongly suggest that the increase of SSR variation is almost linear with the increase of the copy number of each repeat motif. As well, the results suggest that the variability of SSR in the genomes of low-ranking species seem to be more than that of high-ranking species, excluding primates and fungi.

  13. The role of moulting in parasite defence.

    Science.gov (United States)

    Duneau, David; Ebert, Dieter

    2012-08-07

    Parasitic infections consist of a succession of steps during which hosts and parasites interact in specific manners. At each step, hosts can use diverse defence mechanisms to counteract the parasite's attempts to invade and exploit them. Of these steps, the penetration of parasites into the host is a key step for a successful infection and the epithelium is the first line of host defence. The shedding of this protective layer (moulting) is a crucial feature in the life cycle of several invertebrate and vertebrate taxa, and is generally considered to make hosts vulnerable to parasites and predators. Here, we used the crustacean Daphnia magna to test whether moulting influences the likelihood of infection by the castrating bacterium Pasteuria ramosa. This parasite is known to attach to the host cuticula before penetrating into its body. We found that the likelihood of successful parasite infection is greatly reduced if the host moults within 12 h after parasite exposure. Thus, moulting is beneficial for the host being exposed to this parasite. We further show that exposure to the parasite does not induce hosts to moult earlier. We discuss the implications of our findings for host and parasite evolution and epidemiology.

  14. Parasites in Forensic Science: a historic perspective

    Science.gov (United States)

    Cardoso, Rita; Alves, Helena; Richter, Joachim; Botelho, Monica C

    Parasites show a great potential to Forensic Science. Forensic Science is the application of any science and methodology to the legal system. The forensic scientist collects and analyses the physical evidence and produce a report of the results to the court. A parasite is an organism that lives at the expense of another and they exist in any ecosystem. Parasites are the cause of many important diseases. The forensic scientists can use the parasites to identify a crime scene, to determine the murder weapon or simply identify an individual. The applications for parasites in the Forensic Science can be many and more studies should be made in Forensic Parasitology. The most important parasites in Forensic Science are helminths specifically schistosomes. Through history there are many cases where schistosomes were described in autopsies and it was related to the cause of death. Here we review the applications of parasites in Forensic Science and its importance to the forensic scientist.

  15. PARASITIC MITES IN BACKYARD TURKEYS

    Directory of Open Access Journals (Sweden)

    Marco Antonio Camacho-Escobar

    2010-02-01

    Full Text Available To describe the parasitic mites in backyard turkeys, was did this work. The mites were obtain by hand for 30 backyard turkeys in Oaxaca’s Coast region, Mexico; the mites were mount in adhesive paper and wash with the 200X lent in a computer optical microscopy, the parasites size were determinate in the pictures obtained by the microscopy software, the images were sized using a specialist software for it, which relate the number of pixels in the picture with the size of the observation field. Were indentified the species Dermanyssus gallinae, Megninia ginglymura and Ornithonyssus sylviarum, the last two described for first time in backyard turkeys in Mexico. Â

  16. Successes against insects and parasites

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1967-10-15

    With more and more answers being found to intricate problems which have entailed years of research in many parts of the world, some successes can now be claimed in the fight to control insect threats to crops, animals and human beings. Nuclear techniques are playing an important part in world efforts, and recent reports show that they have been effective in pioneer work against crop pests as well as in finding an answer to some diseases caused by parasites

  17. Parasitic Diseases and Psychiatric Illness

    OpenAIRE

    Weiss, Mitchell Gralnick

    1994-01-01

    Distinguishing parasitic diseases from other infections and tropical medical disorders based on microbiological classification is a matter of convenience. Organic brain syndromes are associated with both protozoan and helminthic infections; side-effects of drugs commonly used to treat parasitoses may impair mood and cause anxiety, agitation or psychosis. Emotional states may in turn affect the experience of medical illness. Psychiatrically significant features of medical illness are determine...

  18. Fauna Europaea: Helminths (Animal Parasitic

    Directory of Open Access Journals (Sweden)

    David Gibson

    2014-09-01

    Full Text Available Fauna Europaea provides a public web-service with an index of scientific names (including important synonyms of all living European land and freshwater animals, their geographical distribution at country level (up to the Urals, excluding the Caucasus region, and some additional information. The Fauna Europaea project covers about 230,000 taxonomic names, including 130,000 accepted species and 14,000 accepted subspecies, which is much more than the originally projected number of 100,000 species. This represents a huge effort by more than 400 contributing specialists throughout Europe and is a unique (standard reference suitable for many users in science, government, industry, nature conservation and education. Helminths parasitic in animals represent a large assemblage of worms, representing three phyla, with more than 200 families and almost 4,000 species of parasites from all major vertebrate and many invertebrate groups. A general introduction is given for each of the major groups of parasitic worms, i.e. the Acanthocephala, Monogenea, Trematoda (Aspidogastrea and Digenea, Cestoda and Nematoda. Basic information for each group includes its size, host-range, distribution, morphological features, life-cycle, classification, identification and recent key-works. Tabulations include a complete list of families dealt with, the number of species in each and the name of the specialist responsible for data acquisition, a list of additional specialists who helped with particular groups, and a list of higher taxa dealt with down to the family level. A compilation of useful references is appended.

  19. Parasitic leiomyoma after laparoscopic myomectomy

    Directory of Open Access Journals (Sweden)

    Srithean Lertvikool

    2015-08-01

    Full Text Available A 31-year-old nulligravid underwent laparoscopic myomectomy and the masses were removed by an electric morcellator. Five years later, this patient suffered from acute pelvic pain and received an operation. During laparoscopic surgery, an 8-cm right-sided multiloculated ovarian cyst with chocolate-like content was seen. After adhesiolysis, two parasitic myomas (each ∼2 cm in diameter were found attached to the right ovarian cyst and the other two parasitic myomas (each ∼1 cm in diameter were found at the right infundibulopelvic ligament and omentum respectively. These tumors were successfully removed by laparoscopic procedure. Histopathological examination confirmed that all masses were leiomyomas and the right ovarian cyst was confirmed to be endometriosis. The formation of parasitic myomas was assumed that myomatous fragments during morcellation at the time of myomectomy may have been left behind unintentionally. Thus, morcellator should be used carefully. With that being said, all of the myomatous fragment should be removed after morcellation.

  20. Eosinophilic fasciitis after parasite infection

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    Marta Oliveira

    2016-03-01

    Full Text Available Eosinophilic fasciitis is a systemic inflammatory disease characterized by symmetrical swelling and skin induration of the distal portions of the arms and/or legs, evolving into a scleroderma-like appearance, accompanied by peripheral blood eosinophilia. It is a rare disease with a poorly understood etiology. Corticosteroid treatment remains the standard therapy, either taken alone or in association with an immunosuppressive drug. This paper presents a case of a male patient with palpebral edema and marked eosinophilia, diagnosed with intestinal parasitic infection in October 2006. He was treated with an antiparasitic drug, but both the swelling and the analytical changes remained. This was followed by a skin and muscle biopsy, which turned out to be compatible with eosinophilic fasciitis. There was progressive worsening of the clinical state, with stiffness of the abdominal wall and elevated inflammatory parameters, and the patient was referred to the Immunology Department, medicated with corticosteroids and methotrexate. Over the years there were therapeutic adjustments and other causes were excluded. Currently the patient continues to be monitored, and there is no evidence of active disease. The case described in this article is interesting because of the diagnosis of eosinophilic fasciitis probably associated/coexisting with a parasite infection. This case report differs from others in that there is an uncommon cause associated with the onset of the disease, instead of the common causes such as trauma, medication, non-parasitic infections or cancer.

  1. Plasmodium cysteine repeat modular proteins 1-4: complex proteins with roles throughout the malaria parasite life cycle.

    Science.gov (United States)

    Thompson, Joanne; Fernandez-Reyes, Delmiro; Sharling, Lisa; Moore, Sally G; Eling, Wijnand M; Kyes, Sue A; Newbold, Christopher I; Kafatos, Fotis C; Janse, Chris J; Waters, Andrew P

    2007-06-01

    The Cysteine Repeat Modular Proteins (PCRMP1-4) of Plasmodium, are encoded by a small gene family that is conserved in malaria and other Apicomplexan parasites. They are very large, predicted surface proteins with multipass transmembrane domains containing motifs that are conserved within families of cysteine-rich, predicted surface proteins in a range of unicellular eukaryotes, and a unique combination of protein-binding motifs, including a >100 kDa cysteine-rich modular region, an epidermal growth factor-like domain and a Kringle domain. PCRMP1 and 2 are expressed in life cycle stages in both the mosquito and vertebrate. They colocalize with PfEMP1 (P. falciparum Erythrocyte Membrane Antigen-1) during its export from P. falciparum blood-stage parasites and are exposed on the surface of haemolymph- and salivary gland-sporozoites in the mosquito, consistent with a role in host tissue targeting and invasion. Gene disruption of pcrmp1 and 2 in the rodent malaria model, P. berghei, demonstrated that both are essential for transmission of the parasite from the mosquito to the mouse and has established their discrete and important roles in sporozoite targeting to the mosquito salivary gland. The unprecedented expression pattern and structural features of the PCRMPs thus suggest a variety of roles mediating host-parasite interactions throughout the parasite life cycle.

  2. The independent prokaryotic origins of eukaryotic fructose-1, 6-bisphosphatase and sedoheptulose-1, 7-bisphosphatase and the implications of their origins for the evolution of eukaryotic Calvin cycle

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    Jiang Yong-Hai

    2012-10-01

    Full Text Available Abstract Background In the Calvin cycle of eubacteria, the dephosphorylations of both fructose-1, 6-bisphosphate (FBP and sedoheptulose-1, 7-bisphosphate (SBP are catalyzed by the same bifunctional enzyme: fructose-1, 6-bisphosphatase/sedoheptulose-1, 7-bisphosphatase (F/SBPase, while in that of eukaryotic chloroplasts by two distinct enzymes: chloroplastic fructose-1, 6-bisphosphatase (FBPase and sedoheptulose-1, 7-bisphosphatase (SBPase, respectively. It was proposed that these two eukaryotic enzymes arose from the divergence of a common ancestral eubacterial bifunctional F/SBPase of mitochondrial origin. However, no specific affinity between SBPase and eubacterial FBPase or F/SBPase can be observed in the previous phylogenetic analyses, and it is hard to explain why SBPase and/or F/SBPase are/is absent from most extant nonphotosynthetic eukaryotes according to this scenario. Results Domain analysis indicated that eubacterial F/SBPase of two different resources contain distinct domains: proteobacterial F/SBPases contain typical FBPase domain, while cyanobacterial F/SBPases possess FBPase_glpX domain. Therefore, like prokaryotic FBPase, eubacterial F/SBPase can also be divided into two evolutionarily distant classes (Class I and II. Phylogenetic analysis based on a much larger taxonomic sampling than previous work revealed that all eukaryotic SBPase cluster together and form a close sister group to the clade of epsilon-proteobacterial Class I FBPase which are gluconeogenesis-specific enzymes, while all eukaryotic chloroplast FBPase group together with eukaryotic cytosolic FBPase and form another distinct clade which then groups with the Class I FBPase of diverse eubacteria. Motif analysis of these enzymes also supports these phylogenetic correlations. Conclusions There are two evolutionarily distant classes of eubacterial bifunctional F/SBPase. Eukaryotic FBPase and SBPase do not diverge from either of them but have two independent origins

  3. Beyond Agrobacterium-Mediated Transformation: Horizontal Gene Transfer from Bacteria to Eukaryotes.

    Science.gov (United States)

    Lacroix, Benoît; Citovsky, Vitaly

    2018-03-03

    Besides the massive gene transfer from organelles to the nuclear genomes, which occurred during the early evolution of eukaryote lineages, the importance of horizontal gene transfer (HGT) in eukaryotes remains controversial. Yet, increasing amounts of genomic data reveal many cases of bacterium-to-eukaryote HGT that likely represent a significant force in adaptive evolution of eukaryotic species. However, DNA transfer involved in genetic transformation of plants by Agrobacterium species has traditionally been considered as the unique example of natural DNA transfer and integration into eukaryotic genomes. Recent discoveries indicate that the repertoire of donor bacterial species and of recipient eukaryotic hosts potentially are much wider than previously thought, including donor bacterial species, such as plant symbiotic nitrogen-fixing bacteria (e.g., Rhizobium etli) and animal bacterial pathogens (e.g., Bartonella henselae, Helicobacter pylori), and recipient species from virtually all eukaryotic clades. Here, we review the molecular pathways and potential mechanisms of these trans-kingdom HGT events and discuss their utilization in biotechnology and research.

  4. Quantitative prediction of shrimp disease incidence via the profiles of gut eukaryotic microbiota.

    Science.gov (United States)

    Xiong, Jinbo; Yu, Weina; Dai, Wenfang; Zhang, Jinjie; Qiu, Qiongfen; Ou, Changrong

    2018-04-01

    One common notion is emerging that gut eukaryotes are commensal or beneficial, rather than detrimental. To date, however, surprisingly few studies have been taken to discern the factors that govern the assembly of gut eukaryotes, despite growing interest in the dysbiosis of gut microbiota-disease relationship. Herein, we firstly explored how the gut eukaryotic microbiotas were assembled over shrimp postlarval to adult stages and a disease progression. The gut eukaryotic communities changed markedly as healthy shrimp aged, and converged toward an adult-microbiota configuration. However, the adult-like stability was distorted by disease exacerbation. A null model untangled that the deterministic processes that governed the gut eukaryotic assembly tended to be more important over healthy shrimp development, whereas this trend was inverted as the disease progressed. After ruling out the baseline of gut eukaryotes over shrimp ages, we identified disease-discriminatory taxa (species level afforded the highest accuracy of prediction) that characteristic of shrimp health status. The profiles of these taxa contributed an overall 92.4% accuracy in predicting shrimp health status. Notably, this model can accurately diagnose the onset of shrimp disease. Interspecies interaction analysis depicted how the disease-discriminatory taxa interacted with one another in sustaining shrimp health. Taken together, our findings offer novel insights into the underlying ecological processes that govern the assembly of gut eukaryotes over shrimp postlarval to adult stages and a disease progression. Intriguingly, the established model can quantitatively and accurately predict the incidences of shrimp disease.

  5. Genes of the bovine lungworm Dictyocaulus viviparus associated with transition from pasture to parasitism.

    Science.gov (United States)

    Strube, C; Buschbaum, S; Schnieder, T

    2012-08-01

    Genes necessary to enable nematode parasitic life after free-living larval life are of substantial interest to understand parasitism. We investigated transcriptional changes during transition to parasitism in the bovine lungworm Dictyocaulus viviparus, one of the most important parasites in cattle farming due to substantial economic losses. Upregulated transcripts in either free-living, developmentally arrested L3 or parasitic immature L5 were identified by suppression subtractive hybridization (SSH) followed by differential screening and subsequent virtual Northern blot verification. From 400 sequenced clones of parasitic L5, 372 (93.0%) upregulated high quality ESTs were obtained clustering into 30 contigs and 38 singletons. Most conceptual translated peptides were SCP/TAPS "family" members also known as pathogenesis-related protein (PRP) superfamily (28.5% of total ESTs), cysteine proteases (24.5%), and H-gal-GP orthologues (9.9%). These proteins are predicted to play key roles in fundamental biological processes such as nutrition and development but also parasite-host interactions and immune defense mechanisms. Increased energy requirement of the rapidly developing L5 lungworm stage was obvious in a proportion of 12.2% upregulated ESTs being components of the respiratory chain. From the developmentally arrested L3 stage sequencing of 200 clones resulted in 195 high quality ESTs (97.0%) clustering into 7 contigs and 3 singletons only. Besides a hypothetical protein (70.1% of total ESTs) most transcripts encoded the cleavage stimulation factor subunit 2 (17.5%), which is a component of the poly(A(+)) machinery and found to be involved in gene silencing. Obtained data provide the basis for future fundamental research into genes associated with parasitic lifestyle but also applied research like vaccine and/or drug development. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Potensi Jamur Parasit Telur Sebagai Agens Hayati Pengendali Nematoda Puru Akar Meloidogyne incognita pada Tanaman Tomat

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    Siwi Indarti

    2014-12-01

    Full Text Available Root-knot nematodes Meloidogyne spp. are sedentary endoparasitic that attacks various economically important plants. Utilization of nematode’s fungal egg parasite as biocontrol agents of sedentary endoparasitic nematodes have a good possibility of potential success to be applied in the field level, because this fungi is able to colonize in and causes damage to eggs as well as female nematodes inside the root. The purpose of this research are to know the parasitism ability of this parasitic fungi to Meloidogyne incognita eggs, and its effects on second stage larvae hatching rate and the development of galls number in the host. The result shows that the parasitic fungi, those of Trichoderma, Penicillium, Talaromyces, Fusarium genera were able to parasitize root-knot nematode eggs (25.09 to 89.79%, caused root-knot nematode egg hatching to decrease, suppressed the formation of galls, and reduced the population of second stage nematode larvae in the greenhouse. Nematoda puru-akar Meloidogyne spp. adalah nematoda endoparasitik sedentari, bersifat polifag, dan mempunyai nilai ekonomi tinggi. Pemanfaatan jamur parasit telur sebagai agens hayati pengendali nematoda endoparasitik sedentari mempunyai potensi tingkat keberhasilan tinggi untuk diterapkan pada aras lapangan karena mampu mengoloni dan merusak telur maupun stadium nematoda betina yang terlindungi jaringan tanaman. Tujuan penelitian adalah untuk mengetahui kemampuan parasitasi isolat-isolat jamur parasit telur terhadap telur nematoda Meloidogyne incognita, dan pengaruhnya terhadap tingkat penetasan telur menjadi L-2, serta pembentukan jumlah puru pada tanaman terserang. Hasil penelitian didapatkan bahwa jamur parasit telur yang termasuk genera Tricoderma, Penicillium, Talaromyces, dan Fusarium mampu memarasit telur M. incognita berkisar antara 25,09–89,79%, mengakibatkan penurunan persentase jumlah L-2 nematoda yang bersangkutan, serta menekan pembentukan puru akar pada aplikasi aras

  7. Phytoplankton chytridiomycosis: fungal parasites of phytoplankton and their imprints on the food web dynamics

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    Télesphore eSIME - NGANDO

    2012-10-01

    Full Text Available Parasitism is one of the earlier and common ecological interactions in the nature, occurring in almost all environments. Microbial parasites typically are characterized by their small size, short generation time, and high rates of reproduction, with simple life cycle occurring generally within a single host. They are diverse and ubiquitous in aquatic ecosystems, comprising viruses, prokaryotes and eukaryotes. Recently, environmental 18S-rDNA surveys of microbial eukaryotes have unveiled major infecting agents in pelagic systems, consisting primarily of the fungal order of Chytridiales (chytrids. Chytrids are considered the earlier branch of the Eumycetes and produce motile, flagellated zoospores, characterized by a small size (2-6 µm and a single, posterior flagellum. The existence of these dispersal propagules includes chytrids within the so-called group of zoosporic fungi, which are particularly adapted to the plankton lifestyle where they infect a wide variety of hosts, including fishes, eggs, zooplankton, algae, and other aquatic fungi but primarily freshwater phytoplankton. Related ecological implications are huge because chytrids can killed their hosts, release substrates for microbial processes, and provide nutrient-rich particles as zoospores and short fragments of filamentous inedible hosts for the grazer food chain. Furthermore, based on the observation that phytoplankton chytridiomycosis preferentially impacts the larger size species, blooms of such species (e.g. filamentous cyanobacteria may not totally represent trophic bottlenecks. Besides, chytrid epidemics represent an important driving factor in phytoplankton seasonal successions. In this review, I summarize the knowledge on the diversity, community structure, quantitative importance, and functional roles of fungal chytrids, primarily those who are parasites of phytoplankton, and infer the ecological implications and potentials for the food web dynamics and properties.

  8. Comparative genome analysis reveals a conserved family of actin-like proteins in apicomplexan parasites

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    Sibley L David

    2005-12-01

    Full Text Available Abstract Background The phylum Apicomplexa is an early-branching eukaryotic lineage that contains a number of important human and animal pathogens. Their complex life cycles and unique cytoskeletal features distinguish them from other model eukaryotes. Apicomplexans rely on actin-based motility for cell invasion, yet the regulation of this system remains largely unknown. Consequently, we focused our efforts on identifying actin-related proteins in the recently completed genomes of Toxoplasma gondii, Plasmodium spp., Cryptosporidium spp., and Theileria spp. Results Comparative genomic and phylogenetic studies of apicomplexan genomes reveals that most contain only a single conventional actin and yet they each have 8–10 additional actin-related proteins. Among these are a highly conserved Arp1 protein (likely part of a conserved dynactin complex, and Arp4 and Arp6 homologues (subunits of the chromatin-remodeling machinery. In contrast, apicomplexans lack canonical Arp2 or Arp3 proteins, suggesting they lost the Arp2/3 actin polymerization complex on their evolutionary path towards intracellular parasitism. Seven of these actin-like proteins (ALPs are novel to apicomplexans. They show no phylogenetic associations to the known Arp groups and likely serve functions specific to this important group of intracellular parasites. Conclusion The large diversity of actin-like proteins in apicomplexans suggests that the actin protein family has diverged to fulfill various roles in the unique biology of intracellular parasites. Conserved Arps likely participate in vesicular transport and gene expression, while apicomplexan-specific ALPs may control unique biological traits such as actin-based gliding motility.

  9. Horizontal transfer of a eukaryotic plastid-targeted protein gene to cyanobacteria

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    Keeling Patrick J

    2007-06-01

    Full Text Available Abstract Background Horizontal or lateral transfer of genetic material between distantly related prokaryotes has been shown to play a major role in the evolution of bacterial and archaeal genomes, but exchange of genes between prokaryotes and eukaryotes is not as well understood. In particular, gene flow from eukaryotes to prokaryotes is rarely documented with strong support, which is unusual since prokaryotic genomes appear to readily accept foreign genes. Results Here, we show that abundant marine cyanobacteria in the related genera Synechococcus and Prochlorococcus acquired a key Calvin cycle/glycolytic enzyme from a eukaryote. Two non-homologous forms of fructose bisphosphate aldolase (FBA are characteristic of eukaryotes and prokaryotes respectively. However, a eukaryotic gene has been inserted immediately upstream of the ancestral prokaryotic gene in several strains (ecotypes of Synechococcus and Prochlorococcus. In one lineage this new gene has replaced the ancestral gene altogether. The eukaryotic gene is most closely related to the plastid-targeted FBA from red algae. This eukaryotic-type FBA once replaced the plastid/cyanobacterial type in photosynthetic eukaryotes, hinting at a possible functional advantage in Calvin cycle reactions. The strains that now possess this eukaryotic FBA are scattered across the tree of Synechococcus and Prochlorococcus, perhaps because the gene has been transferred multiple times among cyanobacteria, or more likely because it has been selectively retained only in certain lineages. Conclusion A gene for plastid-targeted FBA has been transferred from red algae to cyanobacteria, where it has inserted itself beside its non-homologous, functional analogue. Its current distribution in Prochlorococcus and Synechococcus is punctate, suggesting a complex history since its introduction to this group.

  10. RNA trafficking in parasitic plant systems

    Science.gov (United States)

    LeBlanc, Megan; Kim, Gunjune; Westwood, James H.

    2012-01-01

    RNA trafficking in plants contributes to local and long-distance coordination of plant development and response to the environment. However, investigations of mobile RNA identity and function are hindered by the inherent difficulty of tracing a given molecule of RNA from its cell of origin to its destination. Several methods have been used to address this problem, but all are limited to some extent by constraints associated with accurately sampling phloem sap or detecting trafficked RNA. Certain parasitic plant species form symplastic connections to their hosts and thereby provide an additional system for studying RNA trafficking. The haustorial connections of Cuscuta and Phelipanche species are similar to graft junctions in that they are able to transmit mRNAs, viral RNAs, siRNAs, and proteins from the host plants to the parasite. In contrast to other graft systems, these parasites form connections with host species that span a wide phylogenetic range, such that a high degree of nucleotide sequence divergence may exist between host and parasites and allow confident identification of most host RNAs in the parasite system. The ability to identify host RNAs in parasites, and vice versa, will facilitate genomics approaches to understanding RNA trafficking. This review discusses the nature of host–parasite connections and the potential significance of host RNAs for the parasite. Additional research on host–parasite interactions is needed to interpret results of RNA trafficking studies, but parasitic plants may provide a fascinating new perspective on RNA trafficking. PMID:22936942

  11. RNA trafficking in parasitic plant systems

    Directory of Open Access Journals (Sweden)

    Megan L LeBlanc

    2012-08-01

    Full Text Available RNA trafficking in plants contributes to local and long-distance coordination of plant development and response to the environment. However, investigations of mobile RNA identity and function are hindered by the inherent difficulty of tracing a given molecule of RNA from its cell of origin to its destination. Several methods have been used to address this problem, but all are limited to some extent by constraints associated with accurately sampling phloem sap or detecting trafficked RNA. Certain parasitic plant species form symplastic connections to their hosts and thereby provide an additional system for studying RNA trafficking. The haustorial connections of Cuscuta and Phelipanche species are similar to graft junctions in that they are able to transmit mRNAs, viral RNAs, siRNAs and proteins from the host plants to the parasite. In contrast to other graft systems, these parasites form connections with host species that span a wide phylogenetic range, such that a high degree of nucleotide sequence divergence may exist between host and parasites and allow confident identification of most host RNAs in the parasite system. The ability to identify host RNAs in parasites, and vice versa, will facilitate genomics approaches to understanding RNA trafficking. This review discusses the nature of host parasite connections and the potential significance of host RNAs for the parasite. Additional research on host-parasite interactions is needed to interpret results of RNA trafficking studies, but parasitic plants may provide a fascinating new perspective on RNA trafficking.

  12. Pressure suppression device

    International Nuclear Information System (INIS)

    Mizumachi, Wataru; Fukuda, Akira; Kitaguchi, Hidemi; Shimizu, Toshiaki.

    1976-01-01

    Object: To relieve and absorb impact wave vibrations caused by steam and non-condensed gases releasing into the pressure suppression chamber at the time of an accident. Structure: The reactor container is filled with inert gases. A safety valve attached main steam pipe is provided to permit the excessive steam to escape, the valve being communicated with the pressure suppression chamber through an exhaust pipe. In the pressure suppression chamber, a doughnut-like cylindrical outer wall is filled at its bottom with pool water to condense the high temperature vapor released through the exhaust pipe. A head portion of a vent tube which leads the exhaust pipe is positioned at the top, and a down comer and an exhaust vent tube are locked by means of steady rests. At the bottom is mounted a pressure adsorber device which adsorbs a pressure from the pool water. (Kamimura, M.)

  13. Structural and biomechanical basis of mitochondrial movement in eukaryotic cells

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    Wu M

    2013-10-01

    Full Text Available Min Wu,1 Aruna Kalyanasundaram,2 Jie Zhu1 1Laboratory of Biomechanics and Engineering, Institute of Biophysics, College of Science, Northwest A&F University, Yangling, Shaanxi, People's Republic of China; 2College of Pharmacology, University of Illinois at Chicago, Chicago, IL, USA Abstract: Mitochondria serve as energy-producing organelles in eukaryotic cells. In addition to providing the energy supply for cells, the mitochondria are also involved in other processes, such as proliferation, differentiation, information transfer, and apoptosis, and play an important role in regulation of cell growth and the cell cycle. In order to achieve these functions, the mitochondria need to move to the corresponding location. Therefore, mitochondrial movement has a crucial role in normal physiologic activity, and any mitochondrial movement disorder will cause irreparable damage to the organism. For example, recent studies have shown that abnormal movement of the mitochondria is likely to be the reason for Charcot–Marie–Tooth disease, amyotrophic lateral sclerosis, Alzheimer's disease, Huntington's disease, Parkinson's disease, and schizophrenia. So, in the cell, especially in the particular polarized cell, the appropriate distribution of mitochondria is crucial to the function and survival of the cell. Mitochondrial movement is mainly associated with the cytoskeleton and related proteins. However, those components play different roles according to cell type. In this paper, we summarize the structural basis of mitochondrial movement, including microtubules, actin filaments, motor proteins, and adaptin, and review studies of the biomechanical mechanisms of mitochondrial movement in different types of cells. Keywords: mitochondrial movement, microtubules, actin filaments, motor proteins, adaptin

  14. MetWAMer: eukaryotic translation initiation site prediction

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    Brendel Volker

    2008-09-01

    Full Text Available Abstract Background Translation initiation site (TIS identification is an important aspect of the gene annotation process, requisite for the accurate delineation of protein sequences from transcript data. We have developed the MetWAMer package for TIS prediction in eukaryotic open reading frames of non-viral origin. MetWAMer can be used as a stand-alone, third-party tool for post-processing gene structure annotations generated by external computational programs and/or pipelines, or directly integrated into gene structure prediction software implementations. Results MetWAMer currently implements five distinct methods for TIS prediction, the most accurate of which is a routine that combines weighted, signal-based translation initiation site scores and the contrast in coding potential of sequences flanking TISs using a perceptron. Also, our program implements clustering capabilities through use of the k-medoids algorithm, thereby enabling cluster-specific TIS parameter utilization. In practice, our static weight array matrix-based indexing method for parameter set lookup can be used with good results in data sets exhibiting moderate levels of 5'-complete coverage. Conclusion We demonstrate that improvements in statistically-based models for TIS prediction can be achieved by taking the class of each potential start-methionine into account pending certain testing conditions, and that our perceptron-based model is suitable for the TIS identification task. MetWAMer represents a well-documented, extensible, and freely available software system that can be readily re-trained for differing target applications and/or extended with existing and novel TIS prediction methods, to support further research efforts in this area.

  15. Methyl labeling and TROSY NMR spectroscopy of proteins expressed in the eukaryote Pichia pastoris

    International Nuclear Information System (INIS)

    Clark, Lindsay; Zahm, Jacob A.; Ali, Rustam; Kukula, Maciej; Bian, Liangqiao; Patrie, Steven M.; Gardner, Kevin H.; Rosen, Michael K.; Rosenbaum, Daniel M.

    2015-01-01

    13 C Methyl TROSY NMR spectroscopy has emerged as a powerful method for studying the dynamics of large systems such as macromolecular assemblies and membrane proteins. Specific 13 C labeling of aliphatic methyl groups and perdeuteration has been limited primarily to proteins expressed in E. coli, preventing studies of many eukaryotic proteins of physiological and biomedical significance. We demonstrate the feasibility of efficient 13 C isoleucine δ1-methyl labeling in a deuterated background in an established eukaryotic expression host, Pichia pastoris, and show that this method can be used to label the eukaryotic protein actin, which cannot be expressed in bacteria. This approach will enable NMR studies of previously intractable targets

  16. The genome of the obligate intracellular parasite Trachipleistophora hominis: new insights into microsporidian genome dynamics and reductive evolution.

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    Eva Heinz

    Full Text Available The dynamics of reductive genome evolution for eukaryotes living inside other eukaryotic cells are poorly understood compared to well-studied model systems involving obligate intracellular bacteria. Here we present 8.5 Mb of sequence from the genome of the microsporidian Trachipleistophora hominis, isolated from an HIV/AIDS patient, which is an outgroup to the smaller compacted-genome species that primarily inform ideas of evolutionary mode for these enormously successful obligate intracellular parasites. Our data provide detailed information on the gene content, genome architecture and intergenic regions of a larger microsporidian genome, while comparative analyses allowed us to infer genomic features and metabolism of the common ancestor of the species investigated. Gene length reduction and massive loss of metabolic capacity in the common ancestor was accompanied by the evolution of novel microsporidian-specific protein families, whose conservation among microsporidians, against a background of reductive evolution, suggests they may have important functions in their parasitic lifestyle. The ancestor had already lost many metabolic pathways but retained glycolysis and the pentose phosphate pathway to provide cytosolic ATP and reduced coenzymes, and it had a minimal mitochondrion (mitosome making Fe-S clusters but not ATP. It possessed bacterial-like nucleotide transport proteins as a key innovation for stealing host-generated ATP, the machinery for RNAi, key elements of the early secretory pathway, canonical eukaryotic as well as microsporidian-specific regulatory elements, a diversity of repetitive and transposable elements, and relatively low average gene density. Microsporidian genome evolution thus appears to have proceeded in at least two major steps: an ancestral remodelling of the proteome upon transition to intracellular parasitism that involved reduction but also selective expansion, followed by a secondary compaction of genome

  17. The Evolutionary History of MAPL (Mitochondria-Associated Protein Ligase and Other Eukaryotic BAM/GIDE Domain Proteins.

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    Jeremy G Wideman

    Full Text Available MAPL (mitochondria-associated protein ligase, also called MULAN/GIDE/MUL1 is a multifunctional mitochondrial outer membrane protein found in human cells that contains a unique BAM (beside a membrane domain and a C-terminal RING-finger domain. MAPL has been implicated in several processes that occur in animal cells such as NF-kB activation, innate immunity and antiviral signaling, suppression of PINK1/parkin defects, mitophagy in skeletal muscle, and caspase-dependent apoptosis. Previous studies demonstrated that the BAM domain is present in diverse organisms in which most of these processes do not occur, including plants, archaea, and bacteria. Thus the conserved function of MAPL and its BAM domain remains an open question. In order to gain insight into its conserved function, we investigated the evolutionary origins of MAPL by searching for homologues in predicted proteomes of diverse eukaryotes. We show that MAPL proteins with a conserved BAM-RING architecture are present in most animals, protists closely related to animals, a single species of fungus, and several multicellular plants and related green algae. Phylogenetic analysis demonstrated that eukaryotic MAPL proteins originate from a common ancestor and not from independent horizontal gene transfers from bacteria. We also determined that two independent duplications of MAPL occurred, one at the base of multicellular plants and another at the base of vertebrates. Although no other eukaryote genome examined contained a verifiable MAPL orthologue, BAM domain-containing proteins were identified in the protists Bigelowiella natans and Ectocarpus siliculosis. Phylogenetic analyses demonstrated that these proteins are more closely related to prokaryotic BAM proteins and therefore likely arose from independent horizontal gene transfers from bacteria. We conclude that MAPL proteins with BAM-RING architectures have been present in the holozoan and viridiplantae lineages since their very beginnings

  18. TIMPs of parasitic helminths - a large-scale analysis of high-throughput sequence datasets.

    Science.gov (United States)

    Cantacessi, Cinzia; Hofmann, Andreas; Pickering, Darren; Navarro, Severine; Mitreva, Makedonka; Loukas, Alex

    2013-05-30

    Tissue inhibitors of metalloproteases (TIMPs) are a multifunctional family of proteins that orchestrate extracellular matrix turnover, tissue remodelling and other cellular processes. In parasitic helminths, such as hookworms, TIMPs have been proposed to play key roles in the host-parasite interplay, including invasion of and establishment in the vertebrate animal hosts. Currently, knowledge of helminth TIMPs is limited to a small number of studies on canine hookworms, whereas no information is available on the occurrence of TIMPs in other parasitic helminths causing neglected diseases. In the present study, we conducted a large-scale investigation of TIMP proteins of a range of neglected human parasites including the hookworm Necator americanus, the roundworm Ascaris suum, the liver flukes Clonorchis sinensis and Opisthorchis viverrini, as well as the schistosome blood flukes. This entailed mining available transcriptomic and/or genomic sequence datasets for the presence of homologues of known TIMPs, predicting secondary structures of defined protein sequences, systematic phylogenetic analyses and assessment of differential expression of genes encoding putative TIMPs in the developmental stages of A. suum, N. americanus and Schistosoma haematobium which infect the mammalian hosts. A total of 15 protein sequences with high homology to known eukaryotic TIMPs were predicted from the complement of sequence data available for parasitic helminths and subjected to in-depth bioinformatic analyses. Supported by the availability of gene manipulation technologies such as RNA interference and/or transgenesis, this work provides a basis for future functional explorations of helminth TIMPs and, in particular, of their role/s in fundamental biological pathways linked to long-term establishment in the vertebrate hosts, with a view towards the development of novel approaches for the control of neglected helminthiases.

  19. Thyroxin hormone suppression treatment

    International Nuclear Information System (INIS)

    Samuel, A.M.

    1999-01-01

    One of the important modalities of treatment of thyroid cancer (TC) after surgery is the administration of thyroxin as an adjuvant treatment. The analysis supports the theory that thyroid suppression plays an important role in patient management. 300 μg of thyroxin, as this is an adequate dose for suppression is given. Ideally the dose should be tailored by testing s-TSH levels. However, since a large number of the patients come from out station cities and villages this is impractical. We therefore depend on clinical criteria of hyperthyroid symptoms and adjust the dose. Very few patients need such adjustment

  20. Introduction of New Parasites in Denmark

    DEFF Research Database (Denmark)

    Enemark, Heidi L.

    examples of such parasites/parasitic diseases: Setaria tundra, a mosquito-borne filarioid nematode which was detected for the first time in Danish deer in 2010. This parasite is usually considered harmless but is capable of causing peritonitis and mortality in ungulates. The newly detected parasite...... was genetically very similar to previously published isolates from France and Italy, and may have been spread to Denmark from southern Europe. Giardia spp. a zoonotic, unicellular parasite (protozoa) well known in Danish livestock but recently found in extremely high numbers in Danish deer with chronic diarrhea...... for the first time in Denmark approximately 10 years ago in 3 foxes from the Copenhagen area. Since then, no systematic surveillance has been performed, and therefore the current prevalence among wildlife and pets is unknown. So far the parasite has not been found in intermediate hosts (rodents) in Denmark...

  1. Interferon-Mediated Innate Immune Responses against Malaria Parasite Liver Stages

    Directory of Open Access Journals (Sweden)

    Jessica L. Miller

    2014-04-01

    Full Text Available Mosquito-transmitted malaria parasites infect hepatocytes and asymptomatically replicate as liver stages. Using RNA sequencing, we show that a rodent malaria liver-stage infection stimulates a robust innate immune response including type I interferon (IFN and IFNγ pathways. Liver-stage infection is suppressed by these infection-engendered innate responses. This suppression was abrogated in mice deficient in IFNγ, the type I IFN α/β receptor (IFNAR, and interferon regulatory factor 3. Natural killer and CD49b+CD3+ natural killer T (NKT cells increased in the liver after a primary infection, and CD1d-restricted NKT cells, which secrete IFNγ, were critical in reducing liver-stage burden of a secondary infection. Lack of IFNAR signaling abrogated the increase in NKT cell numbers in the liver, showing a link between type I IFN signaling, cell recruitment, and subsequent parasite elimination. Our findings demonstrate innate immune sensing of malaria parasite liver-stage infection and that the ensuing innate responses can eliminate the parasite.

  2. Pressure suppressing device

    International Nuclear Information System (INIS)

    Naito, Makoto.

    1980-01-01

    Purpose: To prevent the pressure in the reactor container from excessively increasing even when vapor leaks from the dry well to a space of the suppression chamber, without passing though the suppression pool at the time of loss of coolant accident. Constitution: When vapor of a high temperature and a high pressure at the time of loss of coolant accident flows from the dry well to the suppression chamber without passing through suppression pool water, vapor dose not condense with pool water, and therefore the pressure within the chamber abnormally increases. For this reason, this abnormal pressure is detected by a pressure detector thereby to start the operations of a blower and a pump. By starting the blower, the pressure in the dry well becomes lower than the pressure in the chamber, and vapor entirely passes through the pool water and entirely condenses with the pool water. By starting the pump, the pool water is sprayed over the space of the chamber, and vapor in the space is condensed. (Yoshino, Y.)

  3. Hepatozoon parasites (Apicomplexa: Adeleorina) in bats.

    Science.gov (United States)

    Pinto, C Miguel; Helgen, Kristofer M; Fleischer, Robert C; Perkins, Susan L

    2013-08-01

    We provide the first evidence of Hepatozoon parasites infecting bats. We sequenced a short fragment of the 18S rRNA gene (~600 base pairs) of Hepatozoon parasites from 3 Hipposideros cervinus bats from Borneo. Phylogenies inferred by model-based methods place these Hepatozoon within a clade formed by parasites of reptiles, rodents, and marsupials. We discuss the scenario that bats might be common hosts of Hepatozoon.

  4. Non-coding RNA regulation in pathogenic bacteria located inside eukaryotic cells

    NARCIS (Netherlands)

    Ortega, Alvaro D.; Quereda, Juan J; Pucciarelli, M Graciela; García-del Portillo, Francisco

    2014-01-01

    Intracellular bacterial pathogens have evolved distinct lifestyles inside eukaryotic cells. Some pathogens coexist with the infected cell in an obligate intracellular state, whereas others transit between the extracellular and intracellular environment. Adaptation to these intracellular lifestyles

  5. Extracellular DNA amplicon sequencing reveals high levels of benthic eukaryotic diversity in the central Red Sea

    KAUST Repository

    Pearman, John K.; Irigoien, Xabier; Carvalho, Susana

    2015-01-01

    The present study aims to characterize the benthic eukaryotic biodiversity patterns at a coarse taxonomic level in three areas of the central Red Sea (a lagoon, an offshore area in Thuwal and a shallow coastal area near Jeddah) based

  6. Meeting Report: Minutes from EMBO: Ten Years of Comparative Genomics of Eukaryotic Microorganisms

    Czech Academy of Sciences Publication Activity Database

    Lukeš, Julius; López-García, P.; Louis, E.; Boekhout, T.

    2016-01-01

    Roč. 167, č. 3 (2016), s. 217-221 ISSN 1434-4610 Institutional support: RVO:60077344 Keywords : protist * eukaryotic microorganisms * genomics Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.794, year: 2016

  7. Phylogenetic analysis of P5 P-type ATPases, a eukaryotic lineage of secretory pathway pumps

    DEFF Research Database (Denmark)

    Møller, Annette; Asp, Torben; Holm, Preben Bach

    2008-01-01

    prokaryotic genome. Based on a protein alignment we could group the P5 ATPases into two subfamilies, P5A and P5B that, based on the number of negative charges in conserved trans-membrane segment 4, are likely to have different ion specificities. P5A ATPases are present in all eukaryotic genomes sequenced so......Eukaryotes encompass a remarkable variety of organisms and unresolved lineages. Different phylogenetic analyses have lead to conflicting conclusions as to the origin and associations between lineages and species. In this work, we investigated evolutionary relationship of a family of cation pumps...... exclusive for the secretory pathway of eukaryotes by combining the identification of lineage-specific genes with phylogenetic evolution of common genes. Sequences of P5 ATPases, which are regarded to be cation pumps in the endoplasmic reticulum (ER), were identified in all eukaryotic lineages but not in any...

  8. Changes in bacterial and eukaryotic communities during sewage decomposition in Mississippi River water

    Science.gov (United States)

    Microbial decay processes are one of the mechanisms whereby sewage contamination is reduced in the environment. This decomposition process involves a highly complex array of bacterial and eukaryotic communities from both sewage and ambient waters. However, relatively little is kn...

  9. Phylogenetic profiles of all membrane transport proteins of the malaria parasite highlight new drug targets

    Directory of Open Access Journals (Sweden)

    January Weiner 3rd

    2016-08-01

    Full Text Available In order to combat the on-going malaria epidemic, discovery of new drug targets remains vital. Proteins that are essential to survival and specific to malaria parasites are key candidates. To survive within host cells, the parasites need to acquire nutrients and dispose of waste products across multiple membranes. Additionally, like all eukaryotes, they must redistribute ions and organic molecules between their various internal membrane bound compartments. Membrane transport proteins mediate all of these processes and are considered important mediators of drug resistance as well as drug targets in their own right. Recently, using advanced experimental genetic approaches and streamlined life cycle profiling, we generated a large collection of Plasmodium berghei gene deletion mutants and assigned essential gene functions, highlighting potential targets for prophylactic, therapeutic, and transmission-blocking anti-malarial drugs. Here, we present a comprehensive orthology assignment of all Plasmodium falciparum putative membrane transport proteins and provide a detailed overview of the associated essential gene functions obtained through experimental genetics studies in human and murine model parasites. Furthermore, we discuss the phylogeny of selected potential drug targets identified in our functional screen. We extensively discuss the results in the context of the functional assignments obtained using gene targeting available to date.

  10. The first suicides: a legacy inherited by parasitic protozoans from prokaryote ancestors.

    Science.gov (United States)

    Taylor-Brown, Emilie; Hurd, Hilary

    2013-04-18

    It is more than 25 years since the first report that a protozoan parasite could die by a process resulting in a morphological phenotype akin to apoptosis. Since then these phenotypes have been observed in many unicellular parasites, including trypanosomatids and apicomplexans, and experimental evidence concerning the molecular pathways that are involved is growing. These observations support the view that this form of programmed cell death is an ancient one that predates the evolution of multicellularity. Here we review various hypotheses that attempt to explain the origin of apoptosis, and look for support for these hypotheses amongst the parasitic protists as, with the exception of yeast, most of the work on death mechanisms in unicellular organisms has focussed on them. We examine the role that addiction modules may have played in the original eukaryote cell and the part played by mitochondria in the execution of present day cells, looking for examples from Leishmania spp. Trypanosoma spp. and Plasmodium spp. In addition, the expanding knowledge of proteases, nucleases and other molecules acting in protist execution pathways has enabled comparisons to be made with extant Archaea and bacteria and with biochemical pathways that evolved in metazoans. These comparisons lend support to the original sin hypothesis but also suggest that present-day death pathways may have had multifaceted beginnings.

  11. The Clp Chaperones and Proteases of the Human Malaria Parasite Plasmodium falciparum

    Energy Technology Data Exchange (ETDEWEB)

    Bakkouri, Majida El; Pow, Andre; Mulichak, Anne; Cheung, Kevin L.Y.; Artz, Jennifer D.; Amani, Mehrnaz; Fell, Stuart; de Koning-Ward, Tania F.; Goodman, C. Dean; McFadden, Geoffrey I.; Ortega, Joaquin; Hui, Raymond; Houry, Walid A. (McMaster U.); (Melbourne); (Toronto); (Deakin); (HWMRI)

    2015-02-09

    The Clp chaperones and proteases play an important role in protein homeostasis in the cell. They are highly conserved across prokaryotes and found also in the mitochondria of eukaryotes and the chloroplasts of plants. They function mainly in the disaggregation, unfolding and degradation of native as well as misfolded proteins. Here, we provide a comprehensive analysis of the Clp chaperones and proteases in the human malaria parasite Plasmodium falciparum. The parasite contains four Clp ATPases, which we term PfClpB1, PfClpB2, PfClpC and PfClpM. One PfClpP, the proteolytic subunit, and one PfClpR, which is an inactive version of the protease, were also identified. Expression of all Clp chaperones and proteases was confirmed in blood-stage parasites. The proteins were localized to the apicoplast, a non-photosynthetic organelle that accommodates several important metabolic pathways in P. falciparum, with the exception of PfClpB2 (also known as Hsp101), which was found in the parasitophorous vacuole. Both PfClpP and PfClpR form mostly homoheptameric rings as observed by size-exclusion chromatography, analytical ultracentrifugation and electron microscopy. The X-ray structure of PfClpP showed the protein as a compacted tetradecamer similar to that observed for Streptococcus pneumoniae and Mycobacterium tuberculosis ClpPs. Our data suggest the presence of a ClpCRP complex in the apicoplast of P. falciparum.

  12. Trace Fossil Evidence of Trematode-Bivalve Parasite-Host Interactions in Deep Time.

    Science.gov (United States)

    Huntley, John Warren; De Baets, Kenneth

    2015-01-01

    Parasitism is one of the most pervasive phenomena amongst modern eukaryotic life and yet, relative to other biotic interactions, almost nothing is known about its history in deep time. Digenean trematodes (Platyhelminthes) are complex life cycle parasites, which have practically no body fossil record, but induce the growth of characteristic malformations in the shells of their bivalve hosts. These malformations are readily preserved in the fossil record, but, until recently, have largely been overlooked by students of the fossil record. In this review, we present the various malformations induced by trematodes in bivalves, evaluate their distribution through deep time in the phylogenetic and ecological contexts of their bivalve hosts and explore how various taphonomic processes have likely biased our understanding of trematodes in deep time. Trematodes are known to negatively affect their bivalve hosts in a number of ways including castration, modifying growth rates, causing immobilization and, in some cases, altering host behaviour making the host more susceptible to their own predators. Digeneans are expected to be significant agents of natural selection. To that end, we discuss how bivalves may have adapted to their parasites via heterochrony and suggest a practical methodology for testing such hypotheses in deep time. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Parasites in the Wadden Sea food web

    Science.gov (United States)

    Thieltges, David W.; Engelsma, Marc Y.; Wendling, Carolin C.; Wegner, K. Mathias

    2013-09-01

    While the free-living fauna of the Wadden Sea has received much interest, little is known on the distribution and effects of parasites in the Wadden Sea food web. However, recent studies on this special type of trophic interaction indicate a high diversity of parasites in the Wadden Sea and suggest a multitude of effects on the hosts. This also includes effects on specific predator-prey relationships and the general structure of the food web. Focussing on molluscs, a major group in the Wadden Sea in terms of biomass and abundance and an important link between primary producers and predators, we review existing studies and exemplify the ecological role of parasites in the Wadden Sea food web. First, we give a brief inventory of parasites occurring in the Wadden Sea, ranging from microparasites (e.g. protozoa, bacteria) to macroparasites (e.g. helminths, parasitic copepods) and discuss the effects of spatial scale on heterogeneities in infection levels. We then demonstrate how parasites can affect host population dynamics by acting as a strong mortality factor, causing mollusc mass mortalities. In addition, we will exemplify how parasites can mediate the interaction strength of predator-prey relationships and affect the topological structure of the Wadden Sea food web as a whole. Finally, we highlight some ongoing changes regarding parasitism in the Wadden Sea in the course of global change (e.g. species introduction, climate change) and identify important future research questions to entangle the role of parasites in the Wadden Sea food web.

  14. Mechanisms of host seeking by parasitic nematodes.

    Science.gov (United States)

    Gang, Spencer S; Hallem, Elissa A

    2016-07-01

    The phylum Nematoda comprises a diverse group of roundworms that includes parasites of vertebrates, invertebrates, and plants. Human-parasitic nematodes infect more than one billion people worldwide and cause some of the most common neglected tropical diseases, particularly in low-resource countries [1]. Parasitic nematodes of livestock and crops result in billions of dollars in losses each year [1]. Many nematode infections are treatable with low-cost anthelmintic drugs, but repeated infections are common in endemic areas and drug resistance is a growing concern with increasing therapeutic and agricultural administration [1]. Many parasitic nematodes have an environmental infective larval stage that engages in host seeking, a process whereby the infective larvae use sensory cues to search for hosts. Host seeking is a complex behavior that involves multiple sensory modalities, including olfaction, gustation, thermosensation, and humidity sensation. As the initial step of the parasite-host interaction, host seeking could be a powerful target for preventative intervention. However, host-seeking behavior remains poorly understood. Here we review what is currently known about the host-seeking behaviors of different parasitic nematodes, including insect-parasitic nematodes, mammalian-parasitic nematodes, and plant-parasitic nematodes. We also discuss the neural bases of these behaviors. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Automated Eukaryotic Gene Structure Annotation Using EVidenceModeler and the Program to Assemble Spliced Alignments

    Energy Technology Data Exchange (ETDEWEB)

    Haas, B J; Salzberg, S L; Zhu, W; Pertea, M; Allen, J E; Orvis, J; White, O; Buell, C R; Wortman, J R

    2007-12-10

    EVidenceModeler (EVM) is presented as an automated eukaryotic gene structure annotation tool that reports eukaryotic gene structures as a weighted consensus of all available evidence. EVM, when combined with the Program to Assemble Spliced Alignments (PASA), yields a comprehensive, configurable annotation system that predicts protein-coding genes and alternatively spliced isoforms. Our experiments on both rice and human genome sequences demonstrate that EVM produces automated gene structure annotation approaching the quality of manual curation.

  16. The proteasome of the differently-diverged eukaryote Giardia lamblia and its role in remodeling of the microtubule-based cytoskeleton.

    Science.gov (United States)

    Ray, Atrayee; Sarkar, Srimonti

    2017-08-01

    Giardia lamblia is the causative agent of the diarrheal disease giardiasis, against which only a limited number of drugs are currently available. Increasing reports of resistance to these drugs makes it necessary to identify new cellular targets for designing the next generation of anti-giardial drugs. Towards this goal, therapeutic agents that target the parasitic cellular machinery involved in the functioning of the unique microtubule-based cytoskeleton of the Giardia trophozoites are likely to be effective as microtubule function is not only important for the survival of trophozoites within the host, but also their extensive remodeling is necessary during the transition from trophozoites to cysts. Thus, drugs that affect microtubule remodeling have the potential to not only kill the disease-causing trophozoites, but also inhibit transmission of cysts in the community. Recent studies in other model organisms have indicated that the proteasome plays an integral role in the formation and remodeling of the microtubule-based cytoskeleton. This review draws attention to the various processes by which the giardial proteasome may impact the functioning of its microtubule cytoskeleton and highlights the possible differences of the parasitic proteasome and some of other cellular machinery involved in microtubule remodeling, compared to that of the higher eukaryotic host.

  17. Mapping and characterizing N6-methyladenine in eukaryotic genomes using single molecule real-time sequencing.

    Science.gov (United States)

    Zhu, Shijia; Beaulaurier, John; Deikus, Gintaras; Wu, Tao; Strahl, Maya; Hao, Ziyang; Luo, Guanzheng; Gregory, James A; Chess, Andrew; He, Chuan; Xiao, Andrew; Sebra, Robert; Schadt, Eric E; Fang, Gang

    2018-05-15

    N6-methyladenine (m6dA) has been discovered as a novel form of DNA methylation prevalent in eukaryotes, however, methods for high resolution mapping of m6dA events are still lacking. Single-molecule real-time (SMRT) sequencing has enabled the detection of m6dA events at single-nucleotide resolution in prokaryotic genomes, but its application to detecting m6dA in eukaryotic genomes has not been rigorously examined. Herein, we identified unique characteristics of eukaryotic m6dA methylomes that fundamentally differ from those of prokaryotes. Based on these differences, we describe the first approach for mapping m6dA events using SMRT sequencing specifically designed for the study of eukaryotic genomes, and provide appropriate strategies for designing experiments and carrying out sequencing in future studies. We apply the novel approach to study two eukaryotic genomes. For green algae, we construct the first complete genome-wide map of m6dA at single nucleotide and single molecule resolution. For human lymphoblastoid cells (hLCLs), joint analyses of SMRT sequencing and independent sequencing data suggest that putative m6dA events are enriched in the promoters of young, full length LINE-1 elements (L1s). These analyses demonstrate a general method for rigorous mapping and characterization of m6dA events in eukaryotic genomes. Published by Cold Spring Harbor Laboratory Press.

  18. Defending against parasites: fungus-growing ants combine specialized behaviours and microbial symbionts to protect their fungus gardens.

    Science.gov (United States)

    Little, Ainslie E F; Murakami, Takahiro; Mueller, Ulrich G; Currie, Cameron R

    2006-03-22

    Parasites influence host biology and population structure, and thus shape the evolution of their hosts. Parasites often accelerate the evolution of host defences, including direct defences such as evasion and sanitation and indirect defences such as the management of beneficial microbes that aid in the suppression or removal of pathogens. Fungus-growing ants are doubly burdened by parasites, needing to protect their crops as well as themselves from infection. We show that parasite removal from fungus gardens is more complex than previously realized. In response to infection of their fungal gardens by a specialized virulent parasite, ants gather and compress parasitic spores and hyphae in their infrabuccal pockets, then deposit the resulting pellet in piles near their gardens. We reveal that the ants' infrabuccal pocket functions as a specialized sterilization device, killing spores of the garden parasite Escovopsis. This is apparently achieved through a symbiotic association with actinomycetous bacteria in the infrabuccal pocket that produce antibiotics which inhibit Escovopsis. The use of the infrabuccal pocket as a receptacle to sequester Escovopsis, and as a location for antibiotic administration by the ants' bacterial mutualist, illustrates how the combination of behaviour and microbial symbionts can be a successful defence strategy for hosts.

  19. Characterization of Amoeboaphelidium protococcarum, an algal parasite new to the cryptomycota isolated from an outdoor algal pond used for the production of biofuel.

    Directory of Open Access Journals (Sweden)

    Peter M Letcher

    Full Text Available Mass culture of algae for the production of biofuels is a developing technology designed to offset the depletion of fossil fuel reserves. However, large scale culture of algae in open ponds can be challenging because of incidences of infestation with algal parasites. Without knowledge of the identity of the specific parasite and how to control these pests, algal-based biofuel production will be limited. We have characterized a eukaryotic parasite of Scenedesmus dimorphus growing in outdoor ponds used for biofuel production. We demonstrated that as the genomic DNA of parasite FD01 increases, the concentration of S. dimorphus cells decreases; consequently, this is a highly destructive pathogen. Techniques for culture of the parasite and host were developed, and the endoparasite was identified as the Aphelidea, Amoeboaphelidium protococcarum. Phylogenetic analysis of ribosomal sequences revealed that parasite FD01 placed within the recently described Cryptomycota, a poorly known phylum based on two species of Rozella and environmental samples. Transmission electron microscopy demonstrated that aplanospores of the parasite produced filose pseudopodia, which contained fine fibers the diameter of actin microfilaments. Multiple lipid globules clustered and were associated with microbodies, mitochondria and a membrane cisternae, an arrangement characteristic of the microbody-lipid globule complex of chytrid zoospores. After encystment and attachment to the host cells, the parasite injected its protoplast into the host between the host cell wall and plasma membrane. At maturity the unwalled parasite occupied the entire host cell. After cleavage of the protoplast into aplanospores, a vacuole and lipids remained in the host cell. Amoeboaphelidium protococcarum isolate FD01 is characteristic of the original description of this species and is different from strain X-5 recently characterized. Our results help put a face on the Cryptomycota, revealing that the

  20. Characterization of Amoeboaphelidium protococcarum, an Algal Parasite New to the Cryptomycota Isolated from an Outdoor Algal Pond Used for the Production of Biofuel

    Science.gov (United States)

    Letcher, Peter M.; Lopez, Salvador; Schmieder, Robert; Lee, Philip A.; Behnke, Craig; Powell, Martha J.; McBride, Robert C.

    2013-01-01

    Mass culture of algae for the production of biofuels is a developing technology designed to offset the depletion of fossil fuel reserves. However, large scale culture of algae in open ponds can be challenging because of incidences of infestation with algal parasites. Without knowledge of the identity of the specific parasite and how to control these pests, algal-based biofuel production will be limited. We have characterized a eukaryotic parasite of Scenedesmus dimorphus growing in outdoor ponds used for biofuel production. We demonstrated that as the genomic DNA of parasite FD01 increases, the concentration of S. dimorphus cells decreases; consequently, this is a highly destructive pathogen. Techniques for culture of the parasite and host were developed, and the endoparasite was identified as the Aphelidea, Amoeboaphelidium protococcarum. Phylogenetic analysis of ribosomal sequences revealed that parasite FD01 placed within the recently described Cryptomycota, a poorly known phylum based on two species of Rozella and environmental samples. Transmission electron microscopy demonstrated that aplanospores of the parasite produced filose pseudopodia, which contained fine fibers the diameter of actin microfilaments. Multiple lipid globules clustered and were associated with microbodies, mitochondria and a membrane cisternae, an arrangement characteristic of the microbody-lipid globule complex of chytrid zoospores. After encystment and attachment to the host cells, the parasite injected its protoplast into the host between the host cell wall and plasma membrane. At maturity the unwalled parasite occupied the entire host cell. After cleavage of the protoplast into aplanospores, a vacuole and lipids remained in the host cell. Amoeboaphelidium protococcarum isolate FD01 is characteristic of the original description of this species and is different from strain X-5 recently characterized. Our results help put a face on the Cryptomycota, revealing that the phylum is more

  1. How Many Parasites Species a Frog Might Have? Determinants of Parasite Diversity in South American Anurans.

    Directory of Open Access Journals (Sweden)

    Karla Magalhães Campião

    Full Text Available There is an increasing interest in unveiling the dynamics of parasite infection. Understanding the interaction patterns, and determinants of host-parasite association contributes to filling knowledge gaps in both community and disease ecology. Despite being targeted as a relevant group for conservation efforts, determinants of the association of amphibians and their parasites in broad scales are poorly understood. Here we describe parasite biodiversity in South American amphibians, testing the influence of host body size and geographic range in helminth parasites species richness (PSR. We also test whether parasite diversity is related to hosts' phylogenetic diversity. Results showed that nematodes are the most common anuran parasites. Host-parasite network has a nested pattern, with specialist helminth taxa generally associated with hosts that harbour the richest parasite faunas. Host size is positively correlated with helminth fauna richness, but we found no support for the association of host geographic range and PSR. These results remained consistent after correcting for uneven study effort and hosts' phylogenic correlation. However, we found no association between host and parasite diversity, indicating that more diversified anuran clades not necessarily support higher parasite diversity. Overall, considering both the structure and the determinants of PRS in anurans, we conclude that specialist parasites are more likely to be associated with large anurans, which are the ones harbouring higher PSR, and that the lack of association of PSR with hosts' clade diversification suggests it is strongly influenced by ecological and contemporary constrains.

  2. A ubiquitin carboxyl extension protein secreted from a plant-parasitic nematode Globodera rostochiensis is cleaved in planta to promote plant parasitism.

    Science.gov (United States)

    Chronis, Demosthenis; Chen, Shiyan; Lu, Shunwen; Hewezi, Tarek; Carpenter, Sara C D; Loria, Rosemary; Baum, Thomas J; Wang, Xiaohong

    2013-04-01

    Nematode effector proteins originating from esophageal gland cells play central roles in suppressing plant defenses and in formation of the plant feeding cells that are required for growth and development of cyst nematodes. A gene (GrUBCEP12) encoding a unique ubiquitin carboxyl extension protein (UBCEP) that consists of a signal peptide for secretion, a mono-ubiquitin domain, and a 12 amino acid carboxyl extension protein (CEP12) domain was cloned from the potato cyst nematode Globodera rostochiensis. This GrUBCEP12 gene was expressed exclusively within the nematode's dorsal esophageal gland cell, and was up-regulated in the parasitic second-stage juvenile, correlating with the time when feeding cell formation is initiated. We showed that specific GrUBCEP12 knockdown via RNA interference reduced nematode parasitic success, and that over-expression of the secreted Gr(Δ) (SP) UBCEP12 protein in potato resulted in increased nematode susceptibility, providing direct evidence that this secreted effector is involved in plant parasitism. Using transient expression assays in Nicotiana benthamiana, we found that Gr(Δ) (SP) UBCEP12 is processed into free ubiquitin and a CEP12 peptide (GrCEP12) in planta, and that GrCEP12 suppresses resistance gene-mediated cell death. A target search showed that expression of RPN2a, a gene encoding a subunit of the 26S proteasome, was dramatically suppressed in Gr(Δ) (SP) UBCEP12 but not GrCEP12 over-expression plants when compared with control plants. Together, these results suggest that, when delivered into host plant cells, Gr(Δ) (SP) UBCEP12 becomes two functional units, one acting to suppress plant immunity and the other potentially affecting the host 26S proteasome, to promote feeding cell formation. © 2013 The Authors The Plant Journal © 2013 Blackwell Publishing Ltd.

  3. Energy parasites trigger oncogene mutation.

    Science.gov (United States)

    Pokorný, Jiří; Pokorný, Jan; Jandová, Anna; Kobilková, Jitka; Vrba, Jan; Vrba, Jan

    2016-10-01

    Cancer initialization can be explained as a result of parasitic virus energy consumption leading to randomized genome chemical bonding. Analysis of experimental data on cell-mediated immunity (CMI) containing about 12,000 cases of healthy humans, cancer patients and patients with precancerous cervical lesions disclosed that the specific cancer and the non-specific lactate dehydrogenase-elevating (LDH) virus antigen elicit similar responses. The specific antigen is effective only in cancer type of its origin but the non-specific antigen in all examined cancers. CMI results of CIN patients display both healthy and cancer state. The ribonucleic acid (RNA) of the LDH virus parasitizing on energy reduces the ratio of coherent/random oscillations. Decreased effect of coherent cellular electromagnetic field on bonding electrons in biological macromolecules leads to elevating probability of random genome reactions. Overlapping of wave functions in biological macromolecules depends on energy of the cellular electromagnetic field which supplies energy to bonding electrons for selective chemical bonds. CMI responses of cancer and LDH virus antigens in all examined healthy, precancerous and cancer cases point to energy mechanism in cancer initiation. Dependence of the rate of biochemical reactions on biological electromagnetic field explains yet unknown mechanism of genome mutation.

  4. Local immune mechanisms against parasites

    International Nuclear Information System (INIS)

    Lloyd, S.

    1981-01-01

    The secretory immunological system of the gastrointestinal tract is associated with the production of secretory IgA immunoglobulins. However, despite the fact that secretory IgA antibodies are known to mediate protection against infection with a number of bacteria and viruses, little information is available on their role in protection against infection with parasites. Thus, although elevated levels of IgA immunoglobulins and antibodies are present in the gastrointestinal tract after infection with a number of helminths and protozoa, conclusive evidence that these are associated with protection against infection is often lacking. However, it has now been demonstrated that intestinal IgA antibodies are associated with protection against infection with Taenia taeniaeformis in mice. In addition, secretory IgA antibodies arising from the common mucosal immunological system of the mammary gland are associated with protection against infection with T. taeniaeformis in mice and rats. Thus, since the portal of entry and site of residence of many parasites is the gastrointestinal tract, the secretory immunological system may act as a first line of defence against infection, and it is possible that oral immunization and local stimulation of the gastrointestinal tract may be effective in inducing protection against infection. The use of nuclear techniques (radioisotope-labelled IgA, autoradiography to follow the role of hepatocytes in IgA transport across the liver) are mentioned marginally only in this review

  5. Apoptotic markers in protozoan parasites

    Directory of Open Access Journals (Sweden)

    Fasel Nicolas

    2010-11-01

    Full Text Available Abstract The execution of the apoptotic death program in metazoans is characterized by a sequence of morphological and biochemical changes that include cell shrinkage, presentation of phosphatidylserine at the cell surface, mitochondrial alterations, chromatin condensation, nuclear fragmentation, membrane blebbing and the formation of apoptotic bodies. Methodologies for measuring apoptosis are based on these markers. Except for membrane blebbing and formation of apoptotic bodies, all other events have been observed in most protozoan parasites undergoing cell death. However, while techniques exist to detect these markers, they are often optimised for metazoan cells and therefore may not pick up subtle differences between the events occurring in unicellular organisms and multi-cellular organisms. In this review we discuss the markers most frequently used to analyze cell death in protozoan parasites, paying special attention to changes in cell morphology, mitochondrial activity, chromatin structure and plasma membrane structure/permeability. Regarding classical regulators/executors of apoptosis, we have reviewed the present knowledge of caspase-like and nuclease activities.

  6. Transcriptomic immune response of Tenebrio molitor pupae to parasitization by Scleroderma guani.

    Directory of Open Access Journals (Sweden)

    Jia-Ying Zhu

    Full Text Available BACKGROUND: Host and parasitoid interaction is one of the most fascinating relationships of insects, which is currently receiving an increasing interest. Understanding the mechanisms evolved by the parasitoids to evade or suppress the host immune system is important for dissecting this interaction, while it was still poorly known. In order to gain insight into the immune response of Tenebrio molitor to parasitization by Scleroderma guani, the transcriptome of T. molitor pupae was sequenced with focus on immune-related gene, and the non-parasitized and parasitized T. molitor pupae were analyzed by digital gene expression (DGE analysis with special emphasis on parasitoid-induced immune-related genes using Illumina sequencing. METHODOLOGY/PRINCIPAL FINDINGS: In a single run, 264,698 raw reads were obtained. De novo assembly generated 71,514 unigenes with mean length of 424 bp. Of those unigenes, 37,373 (52.26% showed similarity to the known proteins in the NCBI nr database. Via analysis of the transcriptome data in depth, 430 unigenes related to immunity were identified. DGE analysis revealed that parasitization by S. guani had considerable impacts on the transcriptome profile of T. molitor pupae, as indicated by the significant up- or down-regulation of 3,431 parasitism-responsive transcripts. The expression of a total of 74 unigenes involved in immune response of T. molitor was significantly altered after parasitization. CONCLUSIONS/SIGNIFICANCE: obtained T. molitor transcriptome, in addition to establishing a fundamental resource for further research on functional genomics, has allowed the discovery of a large group of immune genes that might provide a meaningful framework to better understand the immune response in this species and other beetles. The DGE profiling data provides comprehensive T. molitor immune gene expression information at the transcriptional level following parasitization, and sheds valuable light on the molecular

  7. Transcriptomic immune response of Tenebrio molitor pupae to parasitization by Scleroderma guani.

    Science.gov (United States)

    Zhu, Jia-Ying; Yang, Pu; Zhang, Zhong; Wu, Guo-Xing; Yang, Bin

    2013-01-01

    Host and parasitoid interaction is one of the most fascinating relationships of insects, which is currently receiving an increasing interest. Understanding the mechanisms evolved by the parasitoids to evade or suppress the host immune system is important for dissecting this interaction, while it was still poorly known. In order to gain insight into the immune response of Tenebrio molitor to parasitization by Scleroderma guani, the transcriptome of T. molitor pupae was sequenced with focus on immune-related gene, and the non-parasitized and parasitized T. molitor pupae were analyzed by digital gene expression (DGE) analysis with special emphasis on parasitoid-induced immune-related genes using Illumina sequencing. In a single run, 264,698 raw reads were obtained. De novo assembly generated 71,514 unigenes with mean length of 424 bp. Of those unigenes, 37,373 (52.26%) showed similarity to the known proteins in the NCBI nr database. Via analysis of the transcriptome data in depth, 430 unigenes related to immunity were identified. DGE analysis revealed that parasitization by S. guani had considerable impacts on the transcriptome profile of T. molitor pupae, as indicated by the significant up- or down-regulation of 3,431 parasitism-responsive transcripts. The expression of a total of 74 unigenes involved in immune response of T. molitor was significantly altered after parasitization. obtained T. molitor transcriptome, in addition to establishing a fundamental resource for further research on functional genomics, has allowed the discovery of a large group of immune genes that might provide a meaningful framework to better understand the immune response in this species and other beetles. The DGE profiling data provides comprehensive T. molitor immune gene expression information at the transcriptional level following parasitization, and sheds valuable light on the molecular understanding of the host-parasitoid interaction.

  8. Transcriptomic Immune Response of Tenebrio molitor Pupae to Parasitization by Scleroderma guani

    Science.gov (United States)

    Zhu, Jia-Ying; Yang, Pu; Zhang, Zhong; Wu, Guo-Xing; Yang, Bin

    2013-01-01

    Background Host and parasitoid interaction is one of the most fascinating relationships of insects, which is currently receiving an increasing interest. Understanding the mechanisms evolved by the parasitoids to evade or suppress the host immune system is important for dissecting this interaction, while it was still poorly known. In order to gain insight into the immune response of Tenebrio molitor to parasitization by Scleroderma guani, the transcriptome of T. molitor pupae was sequenced with focus on immune-related gene, and the non-parasitized and parasitized T. molitor pupae were analyzed by digital gene expression (DGE) analysis with special emphasis on parasitoid-induced immune-related genes using Illumina sequencing. Methodology/Principal Findings In a single run, 264,698 raw reads were obtained. De novo assembly generated 71,514 unigenes with mean length of 424 bp. Of those unigenes, 37,373 (52.26%) showed similarity to the known proteins in the NCBI nr database. Via analysis of the transcriptome data in depth, 430 unigenes related to immunity were identified. DGE analysis revealed that parasitization by S. guani had considerable impacts on the transcriptome profile of T. molitor pupae, as indicated by the significant up- or down-regulation of 3,431 parasitism-responsive transcripts. The expression of a total of 74 unigenes involved in immune response of T. molitor was significantly altered after parasitization. Conclusions/Significance obtained T. molitor transcriptome, in addition to establishing a fundamental resource for further research on functional genomics, has allowed the discovery of a large group of immune genes that might provide a meaningful framework to better understand the immune response in this species and other beetles. The DGE profiling data provides comprehensive T. molitor immune gene expression information at the transcriptional level following parasitization, and sheds valuable light on the molecular understanding of the host

  9. J/Ψ suppression

    International Nuclear Information System (INIS)

    Giubellino, P.; Abreu, M.C.; Alessandro, B.; Alexa, C.; Arnaldi, R.; Astruc, J.; Atayan, M.; Baglin, C.; Baldit, A.; Bedjidian, M.; Bellaiche, F.; Beole, S.; Boldea, V.; Bordalo, P.; Bussiere, A.; Capony, V.; Casagrande, L.; Castor, J.; Chambon, T.; Chaurand, B.; Chevrot, I.; Cheynis, B.; Chiavassa, E.; Cicalo, C.; Comets, M.P.; Constantinescu, S.; Cruz, J.; De Falco, A.; De Marco, N.; Dellacasa, G.; Devaux, A.; Dita, S.; Drapier, O.; Espagnon, B.; Fargeix, J.; Filippov, S.N.; Fleuret, F.; Force, P.; Gallio, M.; Gavrilov, Y.K.; Gerschel, C.; Giubellino, P.; Golubeva, M.B.; Gonin, M.; Grigorian, A.A.; Grossiord, J.Y.; Guber, F.F.; Guichard, A.; Gulkaninan, H.; Hakobyan, R.; Haroutunian, R.; Idzik, M.; Jouan, D.; Karavitcheva, T.L.; Kluberg, L.; Kurepin, A.B.; Le Bornec, Y.; Lourenco, C.; Mac Cormick, M.; Macciotta, P.; Marzari-Chiesa, A.; Masera, M.; Masoni, A.; Mehrabyan, S.; Mourgues, S.; Musso, A.; Ohlsson-Malek, F.; Petiau, P.; Piccotti, A.; Pizzi, J.R.; Prado da Silva, W.L.; Puddu, G.; Quintans, C.; Racca, C.; Ramello, L.; Ramos, S.; Rato-Mendes, P.; Riccati, L.; Romana, A.; Sartori, S.; Saturnini, P.; Scomparin, E.; Serci, S.; Shahoyan, R.; Silva, S.; Soave, C.; Sonderegger, P.; Tarrago, X.; Temnikov, P.; Topilskaya, N.S.; Usai, G.; Vale, C.; Vercellin, E.; Willis, N.

    1999-01-01

    The cross section for J/Ψ production in Pb-Pb interactions at 158 GeV per nucleon is measured at the CERN SPS by the NA50 experiment. The final results from the 1995 run are presented here together with preliminary ones from the high-statistics 1996 run. An anomalous J/Ψ suppression is observed in Pb-Pb collisions as compared to extrapolations of the previous results obtained by the NA38 experiment with proton and lighter ion beams. The results of the two runs are in good agreement. The results from the 1996 run allow the study of the onset of the anomalous suppression within the same set of data, showing evidence of a sharp change of behaviour around a value of neutral transverse energy, as measured by our electromagnetic calorimeter, of about 50 GeV

  10. Trichostatin A effects on gene expression in the protozoan parasite Entamoeba histolytica

    Directory of Open Access Journals (Sweden)

    Singh Upinder

    2007-07-01

    Full Text Available Abstract Background Histone modification regulates chromatin structure and influences gene expression associated with diverse biological functions including cellular differentiation, cancer, maintenance of genome architecture, and pathogen virulence. In Entamoeba, a deep-branching eukaryote, short chain fatty acids (SCFA affect histone acetylation and parasite development. Additionally, a number of active histone modifying enzymes have been identified in the parasite genome. However, the overall extent of gene regulation tied to histone acetylation is not known. Results In order to identify the genome-wide effects of histone acetylation in regulating E. histolytica gene expression, we used whole-genome expression profiling of parasites treated with SCFA and Trichostatin A (TSA. Despite significant changes in histone acetylation patterns, exposure of parasites to SCFA resulted in minimal transcriptional changes (11 out of 9,435 genes transcriptionally regulated. In contrast, exposure to TSA, a more specific inhibitor of histone deacetylases, significantly affected transcription of 163 genes (122 genes upregulated and 41 genes downregulated. Genes modulated by TSA were not regulated by treatment with 5-Azacytidine, an inhibitor of DNA-methyltransferase, indicating that in E. histolytica the crosstalk between DNA methylation and histone modification is not substantial. However, the set of genes regulated by TSA overlapped substantially with genes regulated during parasite development: 73/122 genes upregulated by TSA exposure were upregulated in E. histolytica cysts (p-value = 6 × 10-53 and 15/41 genes downregulated by TSA exposure were downregulated in E. histolytica cysts (p-value = 3 × 10-7. Conclusion This work represents the first genome-wide analysis of histone acetylation and its effects on gene expression in E. histolytica. The data indicate that SCFAs, despite their ability to influence histone acetylation, have minimal effects on gene

  11. Parasites and cancers: parasite antigens as possible targets for cancer immunotherapy.

    Science.gov (United States)

    Darani, Hossein Yousofi; Yousefi, Morteza

    2012-12-01

    An adverse relationship between some parasite infections and cancer in the human population has been reported by different research groups. Anticancer activity of some parasites such as Trypanosoma cruzi, Toxoplasma gondii, Toxocara canis, Acantamoeba castellani and Plasmodium yoelii has been shown in experimental animals. Moreover, it has been shown that cancer-associated mucin-type O-glycan compositions are made by parasites, therefore cancers and parasites have common antigens. In this report anticancer activities of some parasites have been reviewed and the possible mechanisms of these actions have also been discussed.

  12. Signalling in malaria parasites. The MALSIG consortium.

    NARCIS (Netherlands)

    Doerig, C.; Baker, D.; Billker, O.; Blackman, M.J.; Chitnis, C.; Dhar Kumar, S.; Heussler, V.; Holder, A.A.; Kocken, C.; Krishna, S.; Langsley, G.; Lasonder, E.; Menard, R.; Meissner, M.; Pradel, G.; Ranford-Cartwright, L.; Sharma, A.; Sharma, P.; Tardieux, T.; Tatu, U.; Alano, P.

    2009-01-01

    Depending on their developmental stage in the life cycle, malaria parasites develop within or outside host cells, and in extremely diverse contexts such as the vertebrate liver and blood circulation, or the insect midgut and hemocoel. Cellular and molecular mechanisms enabling the parasite to sense

  13. Considering RNAi experimental design in parasitic helminths.

    Science.gov (United States)

    Dalzell, Johnathan J; Warnock, Neil D; McVeigh, Paul; Marks, Nikki J; Mousley, Angela; Atkinson, Louise; Maule, Aaron G

    2012-04-01

    Almost a decade has passed since the first report of RNA interference (RNAi) in a parasitic helminth. Whilst much progress has been made with RNAi informing gene function studies in disparate nematode and flatworm parasites, substantial and seemingly prohibitive difficulties have been encountered in some species, hindering progress. An appraisal of current practices, trends and ideals of RNAi experimental design in parasitic helminths is both timely and necessary for a number of reasons: firstly, the increasing availability of parasitic helminth genome/transcriptome resources means there is a growing need for gene function tools such as RNAi; secondly, fundamental differences and unique challenges exist for parasite species which do not apply to model organisms; thirdly, the inherent variation in experimental design, and reported difficulties with reproducibility undermine confidence. Ideally, RNAi studies of gene function should adopt standardised experimental design to aid reproducibility, interpretation and comparative analyses. Although the huge variations in parasite biology and experimental endpoints make RNAi experimental design standardization difficult or impractical, we must strive to validate RNAi experimentation in helminth parasites. To aid this process we identify multiple approaches to RNAi experimental validation and highlight those which we deem to be critical for gene function studies in helminth parasites.

  14. [Dipylidium caninum, a rare parasite in man].

    Science.gov (United States)

    Brandstetter, W; Auer, H

    1994-01-01

    Dipylidium caninum, the dog tapeworm, is a common cosmopolitan parasite of dogs and cats. Infestations of man are observed only sporadically. We report the case of a 22 months-old child living in Upper Austria with dipylidiasis. The parasite is briefly outlined with respect to biology, epidemiology, clinical features, diagnosis, therapy and prevention.

  15. Mammalian gastrointestinal parasites in rainforest remnants

    Indian Academy of Sciences (India)

    Here, we studied the gastrointestinal parasites of nonhuman mammalian hosts living in 10 rainforest patches of the Anamalai Tiger Reserve, India. We examined 349 faecal samples of 17 mammalian species and successfully identified 24 gastroin-testinal parasite taxa including 1 protozoan, 2 trematode, 3 cestode and 18 ...

  16. Parasites in the Wadden Sea food web

    NARCIS (Netherlands)

    Thieltges, D.W.; Engelsma, M.Y.; Wendling, C.C.; Wegner, K.M.

    2013-01-01

    While the free-living fauna of the Wadden Sea has received much interest, little is known on the distribution and effects of parasites in the Wadden Sea food web. However, recent studies on this special type of trophic interaction indicate a high diversity of parasites in the Wadden Sea and suggest

  17. The effect of parasites on wildlife

    NARCIS (Netherlands)

    Borgsteede, F.H.M.

    1996-01-01

    Populations of animals which live in the wild are regulated by many biotic and abiotic factors. Parasites are one of the biotic factors. Parasites may influence their hosts in different ways. They may cause the death of the host due to a direct lethal effect or an indirect effect. Direct lethal

  18. Parasitic Rachipagus Conjoined Twins: Surgical Management and ...

    African Journals Online (AJOL)

    parasite upper limb. The parasite was successfully excised. Subsequent follow up of the child has revealed a boy who despite the weakness of his left lower limb is able ... of the limbs. The defect in dura in the lumbar region was also repaired. The limbs excised are shown in figures 5 and 6, with the post operative picture in.

  19. Parasitic nematode interactions with mammals and plants.

    Science.gov (United States)

    Jasmer, Douglas P; Goverse, Aska; Smant, Geert

    2003-01-01

    Parasitic nematodes that infect humans, animals, and plants cause serious diseases that are deleterious to human health and agricultural productivity. Chemical and biological control methods have reduced the impact of these parasites. However, surviving environmental stages lead to persistent reinfection of host species. In addition, development of resistance to nematicides and anthelmintics by these parasites and reduced availability of some nematicides, for environmental protection, pose significant obstacles for current and future prospects of effective parasite control. Due to marked differences in host species, research on animal and plant parasitic nematodes often proceeds independently. Despite the differences between animals and plants, basic cellular properties are shared among these host organisms. Some common properties may be important for mechanisms [homologous or convergent (homoplastic)] by which nematodes successfully infect these diverse hosts or by which animal and plant hosts resist infections by these pathogens. Here we compare host/parasite interactions between plant parasitic nematodes (PPN) and animal parasitic nematodes, with an emphasis on mammalian hosts (MPN). Similarities and differences are considered in the context of progress on molecular dissection of these interactions. A comprehensive coverage is not possible in the space allotted. Instead, an illustrative approach is used to establish examples that, it is hoped, exemplify the value of the comparative approach.

  20. First report of Orobanche ludoviciana parasitizing sunflowers

    Science.gov (United States)

    Broomrape is the common name given to a group of flowering plants belonging to the genus Orobanche that parasitize the roots of higher dicotyledonous plants. More than 100 species of Orobanche have been identified, all of which are obligate parasites that lack chlorophyll and depend upon their host ...

  1. Prevalence of intestinal parasitic infections among patients ...

    African Journals Online (AJOL)

    Gastrointestinal helminths and protozoan parasites may cause mild, acute and chronic human infections. There is inadequate reliable information on the epidemiology of these parasites among patients attending tertiary hospitals in Tanzania. This retrospective study was conducted using hospital data obtained from the ...

  2. Cell fractionation of parasitic protozoa: a review

    Directory of Open Access Journals (Sweden)

    Souza Wanderley de

    2003-01-01

    Full Text Available Cell fractionation, a methodological strategy for obtaining purified organelle preparations, has been applied successfully to parasitic protozoa by a number of investigators. Here we present and discuss the work of several groups that have obtained highly purified subcellular fractions from trypanosomatids, Apicomplexa and trichomonads, and whose work have added substantially to our knowledge of the cell biology of these parasites.

  3. Parasite stress promotes homicide and child maltreatment

    Science.gov (United States)

    Thornhill, Randy; Fincher, Corey L.

    2011-01-01

    Researchers using the parasite-stress theory of human values have discovered many cross-cultural behavioural patterns that inform a range of scholarly disciplines. Here, we apply the theory to major categories of interpersonal violence, and the empirical findings are supportive. We hypothesize that the collectivism evoked by high parasite stress is a cause of adult-on-adult interpersonal violence. Across the US states, parasite stress and collectivism each positively predicts rates of men's and women's slaying of a romantic partner, as well as the rate of male-honour homicide and of the motivationally similar felony-related homicide. Of these four types of homicide, wealth inequality has an independent effect only on rates of male-honour and felony-related homicide. Parasite stress and collectivism also positively predict cross-national homicide rates. Child maltreatment by caretakers is caused, in part, by divestment in offspring of low phenotypic quality, and high parasite stress produces more such offspring than low parasite stress. Rates of each of two categories of the child maltreatment—lethal and non-lethal—across the US states are predicted positively by parasite stress, with wealth inequality and collectivism having limited effects. Parasite stress may be the strongest predictor of interpersonal violence to date. PMID:22042922

  4. Rodent malaria parasites : genome organization & comparative genomics

    NARCIS (Netherlands)

    Kooij, Taco W.A.

    2006-01-01

    The aim of the studies described in this thesis was to investigate the genome organization of rodent malaria parasites (RMPs) and compare the organization and gene content of the genomes of RMPs and the human malaria parasite P. falciparum. The release of the complete genome sequence of P.

  5. Blood parasites from California ducks and geese

    Science.gov (United States)

    Herman, C.M.

    1951-01-01

    Blood smears were procured from 1,011 geese and ducks of 19 species from various locations in California. Parasites were found in 28 individuals. The parasites observed included Haemoproteus hermani, Leucocytozoon simondi, microfilaria, Plasmodium relictum (=P. biziurae), and Plasmodium sp. with elongate gametocytes. This is the first report of a natural infection with a Plasmodium in North American wild ducks.

  6. Characterization of Soil Suppressiveness to Root-Knot Nematodes in Organic Horticulture in Plastic Greenhouse.

    Science.gov (United States)

    Giné, Ariadna; Carrasquilla, Marc; Martínez-Alonso, Maira; Gaju, Núria; Sorribas, Francisco J

    2016-01-01

    The fluctuation of Meloidogyne population density and the percentage of fungal egg parasitism were determined from July 2011 to July 2013 in two commercial organic vegetable production sites (M10.23 and M10.55) in plastic greenhouses, located in northeastern Spain, in order to know the level of soil suppressiveness. Fungal parasites were identified by molecular methods. In parallel, pot tests characterized the level of soil suppressiveness and the fungal species growing from the eggs. In addition, the egg parasitic ability of 10 fungal isolates per site was also assessed. The genetic profiles of fungal and bacterial populations from M10.23 and M10.55 soils were obtained by Denaturing Gradient Gel Electrophoresis (DGGE), and compared with a non-suppressive soil (M10.33). In M10.23, Meloidogyne population in soil decreased progressively throughout the rotation zucchini, tomato, and radish or spinach. The percentage of egg parasitism was 54.7% in zucchini crop, the only one in which eggs were detected. Pochonia chlamydosporia was the only fungal species isolated. In M10.55, nematode densities peaked at the end of the spring-summer crops (tomato, zucchini, and cucumber), but disease severity was lower than expected (0.2-6.3). The percentage of fungal egg parasitism ranged from 3 to 84.5% in these crops. The results in pot tests confirmed the suppressiveness of the M10.23 and M10.55 soils against Meloidogyne. The number of eggs per plant and the reproduction factor of the population were reduced (P < 0.05) in both non-sterilized soils compared to the sterilized ones after one nematode generation. P. chlamydosporia was the only fungus isolated from Meloidogyne eggs. In in vitro tests, P. chlamydosporia isolates were able to parasitize Meloidogyne eggs from 50 to 97% irrespective of the site. DGGE fingerprints revealed a high diversity in the microbial populations analyzed. Furthermore, both bacterial and fungal genetic patterns differentiated suppressive from non-suppressive

  7. Characterization of soil suppressiveness to root-knot nematodes in organic horticulture in plastic greenhouse

    Directory of Open Access Journals (Sweden)

    Ariadna eGiné

    2016-02-01

    Full Text Available The fluctuation of Meloidogyne population density and the percentage of fungal egg parasitism were determined from July 2011 to July 2013 in two commercial organic vegetable production sites (M10.23 and M10.55 in plastic greenhouses, located in northeastern Spain, in order to know the level of soil suppressiveness. Fungal parasites were identified by molecular methods. In parallel, pot tests characterized the level of soil suppressiveness and the fungal species growing from the eggs. In addition, the egg parasitic ability of ten fungal isolates per site was also assessed. The genetic profiles of fungal and bacterial populations from M10.23 and M10.55 soils were obtained by Denaturing Gradient Gel Electrophoresis (DGGE, and compared with a non-suppressive soil (M10.33. In M10.23, Meloidogyne population in soil decreased progressively throughout the rotation zucchini, tomato, and radish or spinach. The percentage of egg parasitism was 54.7% in zucchini crop, the only one in which eggs were detected. Pochonia chlamydosporia was the only fungal species isolated. In M10.55, nematode densities peaked at the end of the spring-summer crops (tomato, zucchini, and cucumber, but disease severity was lower than expected (0.2 to 6.3. The percentage of fungal egg parasitism ranged from 3 to 84.5% in these crops. The results in pot tests confirmed the suppressiveness of the M10.23 and M10.55 soils against Meloidogyne. The number of eggs per plant and the reproduction factor of the population were reduced (P < 0.05 in both non-sterilized soils compared to the sterilized ones after one nematode generation. Pochonia chlamydosporia was the only fungus isolated from Meloidogyne eggs. In in vitro tests, P. chlamydosporia isolates were able to parasitize Meloidogyne eggs from 50 to 97% irrespective of the site. DGGE fingerprints revealed a high diversity in the microbial populations analyzed. Furthermore, both bacterial and fungal genetic patterns differentiated

  8. Timing of host feeding drives rhythms in parasite replication

    KAUST Repository

    Prior, Kimberley F.; van der Veen, Daan R.; O’ Donnell, Aidan J.; Cumnock, Katherine; Schneider, David; Pain, Arnab; Subudhi, Amit; Ramaprasad, Abhinay; Rund, Samuel S. C.; Savill, Nicholas J.; Reece, Sarah E.

    2018-01-01

    by the central, light-entrained circadian oscillator in the brain, determine the timing (phase) of parasite rhythms. Further investigation reveals that parasite rhythms correlate closely with blood glucose rhythms. In addition, we show that parasite rhythms

  9. Immunodiagnosis of parasitic infections using nuclear techniques

    International Nuclear Information System (INIS)

    1985-07-01

    This report documents the recommendations of the ''Advisory Group on Immunodiagnosis of Parasitic Infections Using Nuclear Techniques'' with a focus on malaria, schistosomiasis and filariasis. Radionuclide tracers are considered an important component of present and future immunological methods for the assessment of the host's humoral and cellular immunity to the parasite and the detection of parasite antigen(s) in human body fluids. The Advisory Group has concluded that there is a continuing need for the development and application of immunodiagnostic methods in parasitic diseases. This report concerns methods which are currently or potentially applicable to immunodiagnostic investigations in parasitic diseases. Reference is made, where appropriate, to recent developments in research which may lead to improvement and standardization of methods now available and the development of new methodology. Separate abstracts on various papers presented were prepared

  10. Parasites and poverty: the case of schistosomiasis.

    Science.gov (United States)

    King, Charles H

    2010-02-01

    Simultaneous and sequential transmission of multiple parasites, and their resultant overlapping chronic infections, are facts of life in many underdeveloped rural areas. These represent significant but often poorly measured health and economic burdens for affected populations. For example, the chronic inflammatory process associated with long-term schistosomiasis contributes to anaemia and undernutrition, which, in turn, can lead to growth stunting, poor school performance, poor work productivity, and continued poverty. To date, most national and international programs aimed at parasite control have not considered the varied economic and ecological factors underlying multi-parasite transmission, but some are beginning to provide a coordinated approach to control. In addition, interest is emerging in new studies for the re-evaluation and recalibration of the health burden of helminthic parasite infection. Their results should highlight the strong potential of integrated parasite control in efforts for poverty reduction. Copyright 2009 Elsevier B.V. All rights reserved.

  11. Subversion of complement by hematophagous parasites.

    Science.gov (United States)

    Schroeder, Hélène; Skelly, Patrick J; Zipfel, Peter F; Losson, Bertrand; Vanderplasschen, Alain

    2009-01-01

    The complement system is a crucial part of innate and adaptive immunity which exerts a significant evolutionary pressure on pathogens. It has selected for those pathogens, mainly microorganisms but also parasites, that have evolved countermeasures. The characterization of how pathogens evade complement attack is a rapidly developing field of current research. In recent years, multiple complement evasion strategies have been characterized. In this review, we focus on complement escape mechanisms expressed by hematophagous parasites, a heterogeneous group of metazoan parasites that share the property of ingesting the whole blood of their host. Complement inhibition is crucial for parasite survival within the host tissue or to facilitate blood feeding. Finally, complement inhibition by hematophagous parasites may also contribute to their success as pathogen vectors.

  12. Coccidian intestinal parasites in the Priapulidae (Priapulida).

    Science.gov (United States)

    Saldarriaga, J F; Storch, V

    1997-01-01

    Four relatively uncommon members of the family Priapulidae (Priapulida) from very different parts of the world were examined to determine the presence of a parasitic coccidian in their midgut. The parasite was found in three of those priapulid species, Priapulopsis bicaudatus, P. australis, and Halicryptus higginsi, but not in the fourth one, Priapulus tuberculatospinosus. Using electron-microscopy techniques, we compared parasites of the different species with one another and with a parasite of Priapulus caudatus investigated by McLean in 1984. All of these parasites apparently belong to the same species and are likely to be Alveocystis intestinalis, a coccidian first described by Beltenev from P. caudatus and H. spinulosus. The present work greatly expands the geographical range of Alveocystis intestinalis and documents an uncommon case of low host specificity in eimeriid coccidians.

  13. A description of parasites from Iranian snakes.

    Science.gov (United States)

    Nasiri, Vahid; Mobedi, Iraj; Dalimi, Abdolhossein; Mirakabadi, Abbas Zare; Ghaffarifar, Fatemeh; Teymurzadeh, Shohreh; Karimi, Gholamreza; Abdoli, Amir; Paykari, Habibollah

    2014-12-01

    Little is known of the parasitic fauna of terrestrial snakes in Iran. This study aimed to evaluate the parasitic infection rates of snakes in Iran. A total of 87 snakes belonging to eight different species, that were collected between May 2012 and September 2012 and died after the hold in captivity, under which they were kept for taking poisons, were examined for the presence of gastrointestinal and blood parasites. According to our study 12 different genera of endoparasites in 64 (73.56%) of 87 examined snakes were determined. Forty one snakes (47.12%) had gastrointestinal parasites. In prepared blood smears, it was found that in 23 (26.43%) of 87 examined snakes there are at least one hemoparasite. To our knowledge, these are the first data on the internal parasitic fauna of Iranian terrestrial snakes and our findings show a higher prevalence of these organisms among them. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Amplicon-Based Pyrosequencing Reveals High Diversity of Protistan Parasites in Ships' Ballast Water: Implications for Biogeography and Infectious Diseases.

    Science.gov (United States)

    Pagenkopp Lohan, K M; Fleischer, R C; Carney, K J; Holzer, K K; Ruiz, G M

    2016-04-01

    Ships' ballast water (BW) commonly moves macroorganisms and microorganisms across the world's oceans and along coasts; however, the majority of these microbial transfers have gone undetected. We applied high-throughput sequencing methods to identify microbial eukaryotes, specifically emphasizing the protistan parasites, in ships' BW collected from vessels calling to the Chesapeake Bay (Virginia and Maryland, USA) from European and Eastern Canadian ports. We utilized tagged-amplicon 454 pyrosequencing with two general primer sets, amplifying either the V4 or V9 domain of the small subunit (SSU) of the ribosomal RNA (rRNA) gene complex, from total DNA extracted from water samples collected from the ballast tanks of bulk cargo vessels. We detected a diverse group of protistan taxa, with some known to contain important parasites in marine systems, including Apicomplexa (unidentified apicomplexans, unidentified gregarines, Cryptosporidium spp.), Dinophyta (Blastodinium spp., Euduboscquella sp., unidentified syndinids, Karlodinium spp., Syndinium spp.), Perkinsea (Parvilucifera sp.), Opisthokonta (Ichthyosporea sp., Pseudoperkinsidae, unidentified ichthyosporeans), and Stramenopiles (Labyrinthulomycetes). Further characterization of groups with parasitic taxa, consisting of phylogenetic analyses for four taxa (Cryptosporidium spp., Parvilucifera spp., Labyrinthulomycetes, and Ichthyosporea), revealed that sequences were obtained from both known and novel lineages. This study demonstrates that high-throughput sequencing is a viable and sensitive method for detecting parasitic protists when present and transported in the ballast water of ships. These data also underscore the potential importance of human-aided dispersal in the biogeography of these microbes and emerging diseases in the world's oceans.

  15. The origin of malarial parasites in orangutans.

    Directory of Open Access Journals (Sweden)

    M Andreína Pacheco

    Full Text Available BACKGROUND: Recent findings of Plasmodium in African apes have changed our perspectives on the evolution of malarial parasites in hominids. However, phylogenetic analyses of primate malarias are still missing information from Southeast Asian apes. In this study, we report molecular data for a malaria parasite lineage found in orangutans. METHODOLOGY/PRINCIPAL FINDINGS: We screened twenty-four blood samples from Pongo pygmaeus (Kalimantan, Indonesia for Plasmodium parasites by PCR. For all the malaria positive orangutan samples, parasite mitochondrial genomes (mtDNA and two antigens: merozoite surface protein 1 42 kDa (MSP-1(42 and circumsporozoite protein gene (CSP were amplified, cloned, and sequenced. Fifteen orangutans tested positive and yielded 5 distinct mitochondrial haplotypes not previously found. The haplotypes detected exhibited low genetic divergence among them, indicating that they belong to one species. We report phylogenetic analyses using mitochondrial genomes, MSP-1(42 and CSP. We found that the orangutan malaria parasite lineage was part of a monophyletic group that includes all the known non-human primate malaria parasites found in Southeast Asia; specifically, it shares a recent common ancestor with P. inui (a macaque parasite and P. hylobati (a gibbon parasite suggesting that this lineage originated as a result of a host switch. The genetic diversity of MSP-1(42 in orangutans seems to be under negative selection. This result is similar to previous findings in non-human primate malarias closely related to P. vivax. As has been previously observed in the other Plasmodium species found in non-human primates, the CSP shows high polymorphism in the number of repeats. However, it has clearly distinctive motifs from those previously found in other malarial parasites. CONCLUSION: The evidence available from Asian apes indicates that these parasites originated independently from those found in Africa, likely as the result of host

  16. Identification of a secreted casein kinase 1 in Leishmania donovani: effect of protein over expression on parasite growth and virulence.

    Directory of Open Access Journals (Sweden)

    Mary Dan-Goor

    Full Text Available Casein kinase 1 (CK1 plays an important role in eukaryotic signaling pathways, and their substrates include key regulatory proteins involved in cell differentiation, proliferation and chromosome segregation. The Leishmania genome encodes six potential CK1 isoforms, of which five have orthologs in other trypanosomatidae. Leishmania donovani CK1 isoform 4 (Ldck1.4, orthologous to LmjF27.1780 is unique to Leishmania and contains a putative secretion signal peptide. The full-length gene and three shorter constructs were cloned and expressed in E. coli as His-tag proteins. Only the full-length 62.3 kDa protein showed protein kinase activity indicating that the N-terminal and C-terminal domains are essential for protein activity. LdCK1.4-FLAG was stably over expressed in L. donovani, and shown by immunofluorescence to be localized primarily in the cytosol. Western blotting using anti-FLAG and anti-CK1.4 antibodies showed that this CK1 isoform is expressed and secreted by promastigotes. Over expression of LdCK1.4 had a significant effect on promastigote growth in culture with these parasites growing to higher cell densities than the control parasites (wild-type or Ld:luciferase, P<0.001. Analysis by flow cytometry showed a higher percentage, ∼4-5-fold, of virulent metacyclic promastigotes on day 3 among the LdCK1.4 parasites. Finally, parasites over expressing LdCK1.4 gave significantly higher infections of mouse peritoneal macrophages compared to wild-type parasites, 28.6% versus 6.3%, respectively (p = 0.0005. These results suggest that LdCK1.4 plays an important role in parasite survival and virulence. Further studies are needed to validate CK1.4 as a therapeutic target in Leishmania.

  17. Lysine acetylation in sexual stage malaria parasites is a target for antimalarial small molecules.

    Science.gov (United States)

    Trenholme, Katharine; Marek, Linda; Duffy, Sandra; Pradel, Gabriele; Fisher, Gillian; Hansen, Finn K; Skinner-Adams, Tina S; Butterworth, Alice; Ngwa, Che Julius; Moecking, Jonas; Goodman, Christopher D; McFadden, Geoffrey I; Sumanadasa, Subathdrage D M; Fairlie, David P; Avery, Vicky M; Kurz, Thomas; Andrews, Katherine T

    2014-07-01

    Therapies to prevent transmission of malaria parasites to the mosquito vector are a vital part of the global malaria elimination agenda. Primaquine is currently the only drug with such activity; however, its use is limited by side effects. The development of transmission-blocking strategies requires an understanding of sexual stage malaria parasite (gametocyte) biology and the identification of new drug leads. Lysine acetylation is an important posttranslational modification involved in regulating eukaryotic gene expression and other essential processes. Interfering with this process with histone deacetylase (HDAC) inhibitors is a validated strategy for cancer and other diseases, including asexual stage malaria parasites. Here we confirm the expression of at least one HDAC protein in Plasmodium falciparum gametocytes and show that histone and nonhistone protein acetylation occurs in this life cycle stage. The activity of the canonical HDAC inhibitors trichostatin A (TSA) and suberoylanilide hydroxamic acid (SAHA; Vorinostat) and a panel of novel HDAC inhibitors on early/late-stage gametocytes and on gamete formation was examined. Several compounds displayed early/late-stage gametocytocidal activity, with TSA being the most potent (50% inhibitory concentration, 70 to 90 nM). In contrast, no inhibitory activity was observed in P. falciparum gametocyte exflagellation experiments. Gametocytocidal HDAC inhibitors caused hyperacetylation of gametocyte histones, consistent with a mode of action targeting HDAC activity. Our data identify HDAC inhibitors as being among a limited number of compounds that target both asexual and sexual stage malaria parasites, making them a potential new starting point for gametocytocidal drug leads and valuable tools for dissecting gametocyte biology. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  18. Metabarcoding analysis of eukaryotic microbiota in the gut of HIV-infected patients.

    Directory of Open Access Journals (Sweden)

    Ibrahim Hamad

    Full Text Available Research on the relationship between changes in the gut microbiota and human disease, including AIDS, is a growing field. However, studies on the eukaryotic component of the intestinal microbiota have just begun and have not yet been conducted in HIV-infected patients. Moreover, eukaryotic community profiling is influenced by the use of different methodologies at each step of culture-independent techniques. Herein, initially, four DNA extraction protocols were compared to test the efficiency of each method in recovering eukaryotic DNA from fecal samples. Our results revealed that recovering eukaryotic components from fecal samples differs significantly among DNA extraction methods. Subsequently, the composition of the intestinal eukaryotic microbiota was evaluated in HIV-infected patients and healthy volunteers through clone sequencing, high-throughput sequencing of nuclear ribosomal internal transcribed spacers 1 (ITS1 and 2 (ITS2 amplicons and real-time PCRs. Our results revealed that not only richness (Chao-1 index and alpha diversity (Shannon diversity differ between HIV-infected patients and healthy volunteers, depending on the molecular strategy used, but also the global eukaryotic community composition, with little overlapping taxa found between techniques. Moreover, our results based on cloning libraries and ITS1/ITS2 metabarcoding sequencing showed significant differences in fungal composition between HIV-infected patients and healthy volunteers, but without distinct clusters separating the two groups. Malassezia restricta was significantly more prevalent in fecal samples of HIV-infected patients, according to cloning libraries, whereas operational taxonomic units (OTUs belonging to Candida albicans and Candida tropicalis were significantly more abundant in fecal samples of HIV-infected patients compared to healthy subjects in both ITS subregions. Finally, real-time PCR showed the presence of Microsporidia, Giardia lamblia, Blastocystis

  19. Molecular Phylogeny of the Parasitic Dinoflagellate Chytriodinium within the Gymnodinium Clade (Gymnodiniales, Dinophyceae).

    Science.gov (United States)

    Gómez, Fernando; Skovgaard, Alf

    2015-01-01

    The dinoflagellate genus Chytriodinium, an ectoparasite of copepod eggs, is reported for the first time in the North and South Atlantic Oceans. We provide the first large subunit rDNA (LSU rDNA) and Internal Transcribed Spacer 1 (ITS1) sequences, which were identical in both hemispheres for the Atlantic Chytriodinium sp. The first complete small subunit ribosomal DNA (SSU rDNA) of the Atlantic Chytriodinium sp. suggests that the specimens belong to an undescribed species. This is the first evidence of the split of the Gymnodinium clade: one for the parasitic forms of Chytriodiniaceae (Chytriodinium, Dissodinium), and other clade for the free-living species. © 2014 The Author(s) Journal of Eukaryotic Microbiology © 2014 International Society of Protistologists.

  20. Proton-pumping rhodopsins are abundantly expressed by microbial eukaryotes in a high-Arctic fjord.

    Science.gov (United States)

    Vader, Anna; Laughinghouse, Haywood D; Griffiths, Colin; Jakobsen, Kjetill S; Gabrielsen, Tove M

    2018-02-01

    Proton-pumping rhodopsins provide an alternative pathway to photosynthesis by which solar energy can enter the marine food web. Rhodopsin genes are widely found in marine bacteria, also in the Arctic, and were recently reported from several eukaryotic lineages. So far, little is known about rhodopsin expression in Arctic eukaryotes. In this study, we used metatranscriptomics and 18S rDNA tag sequencing to examine the mid-summer function and composition of marine protists (size 0.45-10 µm) in the high-Arctic Billefjorden (Spitsbergen), especially focussing on the expression of microbial proton-pumping rhodopsins. Rhodopsin transcripts were highly abundant, at a level similar to that of genes involved in photosynthesis. Phylogenetic analyses placed the environmental rhodopsins within disparate eukaryotic lineages, including dinoflagellates, stramenopiles, haptophytes and cryptophytes. Sequence comparison indicated the presence of several functional types, including xanthorhodopsins and a eukaryotic clade of proteorhodopsin. Transcripts belonging to the proteorhodopsin clade were also abundant in published metatranscriptomes from other oceanic regions, suggesting a global distribution. The diversity and abundance of rhodopsins show that these light-driven proton pumps play an important role in Arctic microbial eukaryotes. Understanding this role is imperative to predicting the future of the Arctic marine ecosystem faced by a changing light climate due to diminishing sea-ice. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  1. Diversity patterns of microbial eukaryotes mirror those of bacteria in Antarctic cryoconite holes.

    Science.gov (United States)

    Sommers, Pacifica; Darcy, John L; Gendron, Eli M S; Stanish, Lee F; Bagshaw, Elizabeth A; Porazinska, Dorota L; Schmidt, Steven K

    2018-01-01

    Ice-lidded cryoconite holes on glaciers in the Taylor Valley, Antarctica, provide a unique system of natural mesocosms for studying community structure and assembly. We used high-throughput DNA sequencing to characterize both microbial eukaryotic communities and bacterial communities within cryoconite holes across three glaciers to study similarities in their spatial patterns. We expected that the alpha (phylogenetic diversity) and beta (pairwise community dissimilarity) diversity patterns of eukaryotes in cryoconite holes would be related to those of bacteria, and that they would be related to the biogeochemical gradient within the Taylor Valley. We found that eukaryotic alpha and beta diversity were strongly related to those of bacteria across scales ranging from 140 m to 41 km apart. Alpha diversity of both was significantly related to position in the valley and surface area of the cryoconite hole, with pH also significantly correlated with the eukaryotic diversity. Beta diversity for both bacteria and eukaryotes was significantly related to position in the valley, with bacterial beta diversity also related to nitrate. These results are consistent with transport of sediments onto glaciers occurring primarily at local scales relative to the size of the valley, thus creating feedbacks in local chemistry and diversity. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  2. Genetic exchange in eukaryotes through horizontal transfer: connected by the mobilome.

    Science.gov (United States)

    Wallau, Gabriel Luz; Vieira, Cristina; Loreto, Élgion Lúcio Silva

    2018-01-01

    All living species contain genetic information that was once shared by their common ancestor. DNA is being inherited through generations by vertical transmission (VT) from parents to offspring and from ancestor to descendant species. This process was considered the sole pathway by which biological entities exchange inheritable information. However, Horizontal Transfer (HT), the exchange of genetic information by other means than parents to offspring, was discovered in prokaryotes along with strong evidence showing that it is a very important process by which prokaryotes acquire new genes. For some time now, it has been a scientific consensus that HT events were rare and non-relevant for evolution of eukaryotic species, but there is growing evidence supporting that HT is an important and frequent phenomenon in eukaryotes as well. Here, we will discuss the latest findings regarding HT among eukaryotes, mainly HT of transposons (HTT), establishing HTT once and for all as an important phenomenon that should be taken into consideration to fully understand eukaryotes genome evolution. In addition, we will discuss the latest development methods to detect such events in a broader scale and highlight the new approaches which should be pursued by researchers to fill the knowledge gaps regarding HTT among eukaryotes.

  3. Arginine deiminase pathway enzymes: evolutionary history in metamonads and other eukaryotes.

    Science.gov (United States)

    Novák, Lukáš; Zubáčová, Zuzana; Karnkowska, Anna; Kolisko, Martin; Hroudová, Miluše; Stairs, Courtney W; Simpson, Alastair G B; Keeling, Patrick J; Roger, Andrew J; Čepička, Ivan; Hampl, Vladimír

    2016-10-06

    Multiple prokaryotic lineages use the arginine deiminase (ADI) pathway for anaerobic energy production by arginine degradation. The distribution of this pathway among eukaryotes has been thought to be very limited, with only two specialized groups living in low oxygen environments (Parabasalia and Diplomonadida) known to possess the complete set of all three enzymes. We have performed an extensive survey of available sequence data in order to map the distribution of these enzymes among eukaryotes and to reconstruct their phylogenies. We have found genes for the complete pathway in almost all examined representatives of Metamonada, the anaerobic protist group that includes parabasalids and diplomonads. Phylogenetic analyses indicate the presence of the complete pathway in the last common ancestor of metamonads and heterologous transformation experiments suggest its cytosolic localization in the metamonad ancestor. Outside Metamonada, the complete pathway occurs rarely, nevertheless, it was found in representatives of most major eukaryotic clades. Phylogenetic relationships of complete pathways are consistent with the presence of the Archaea-derived ADI pathway in the last common ancestor of all eukaryotes, although other evolutionary scenarios remain possible. The presence of the incomplete set of enzymes is relatively common among eukaryotes and it may be related to the fact that these enzymes are involved in other cellular processes, such as the ornithine-urea cycle. Single protein phylogenies suggest that the evolutionary history of all three enzymes has been shaped by frequent gene losses and horizontal transfers, which may sometimes be connected with their diverse roles in cellular metabolism.

  4. Evolution of glutamate dehydrogenase genes: evidence for lateral gene transfer within and between prokaryotes and eukaryotes

    Directory of Open Access Journals (Sweden)

    Roger Andrew J

    2003-06-01

    Full Text Available Abstract Background Lateral gene transfer can introduce genes with novel functions into genomes or replace genes with functionally similar orthologs or paralogs. Here we present a study of the occurrence of the latter gene replacement phenomenon in the four gene families encoding different classes of glutamate dehydrogenase (GDH, to evaluate and compare the patterns and rates of lateral gene transfer (LGT in prokaryotes and eukaryotes. Results We extend the taxon sampling of gdh genes with nine new eukaryotic sequences and examine the phylogenetic distribution pattern of the various GDH classes in combination with maximum likelihood phylogenetic analyses. The distribution pattern analyses indicate that LGT has played a significant role in the evolution of the four gdh gene families. Indeed, a number of gene transfer events are identified by phylogenetic analyses, including numerous prokaryotic intra-domain transfers, some prokaryotic inter-domain transfers and several inter-domain transfers between prokaryotes and microbial eukaryotes (protists. Conclusion LGT has apparently affected eukaryotes and prokaryotes to a similar extent within the gdh gene families. In the absence of indications that the evolution of the gdh gene families is radically different from other families, these results suggest that gene transfer might be an important evolutionary mechanism in microbial eukaryote genome evolution.

  5. The pressure suppression system

    International Nuclear Information System (INIS)

    Aust, E.

    1985-01-01

    Nuclear plants with boiling water reactors have a safety containment with a pressure suppression system (PSS). Proceeding on significant self-developments, today the three PSS-lines of General Electric Co. (GE), Kraftwerk Union AG (KWU) and ASEA-ATOM are predominant, which are currently represented by the MARK III type, the KWU type 72 and the BWR 75 containment. In addition, there are special developments for the nuclear ship propulsion and for the pressurized water reactors in the Soviet Union. Key design values of the PSS allow a first valuation of its loads during a hypothetical loss-of-coolant accident. (orig.) [de

  6. Function of Rad51 paralogs in eukaryotic homologous recombinational repair

    International Nuclear Information System (INIS)

    Liu, N.; Skowronek, K.

    2003-01-01

    Full text: Homologous recombinational repair (HRR) is an important mechanism for maintaining genetic integrity and cancer prevention by accurately repair of DNA double strand breaks induced by environmental insults or occurred in DNA replication. A critical step in HRR is the polymerization of Rad51 on single stranded DNA to form nuclear protein filaments, the later conduct DNA strand paring and exchange between homologous strands. A number of proteins, including replication protein A (RPA), Rad52 and Rad51 paralogs, are suggested to modulate or facilitate the process of Rad51 filament formation. Five Rad51 paralogs, namely XRCC2, XRCC3, Rad51B, Rad51C and Rad51D have been identified in eucaryotic cells. These proteins show distant protein sequence identity to Rad51, to yeast Rad51 paralogs (Rad55 and Rad57) and to each other. Hamster or chicken mutants of Rad51 paralogs exhibit hypersensitivity to a variety of DNA damaging agents, especially cross-linking agents, and are defective in assembly of Rad51 onto HRR site after DNA damage. Recent data from our and other labs showed that Rad51 paralogs constitute two distinct complexes in cell extracts, one contains XRCC2, Rad51B, Rad51C and Rad51D, and the other contains Rad51C and XRCC3. Rad51C is involved in both complexes. Our results also showed that XRCC3-Rad51C complex interacts with Rad51 in vivo. Furthermore, overexpression of Rad52 can partially suppress the hypersensitivity of XRCC2 mutant irs1 to ionizing radiation and corrected the defects in Rad51 focus formation. These results suggest that XRCC2 and other Rad51 paralogs play a mediator function to Rad51 in the early stage of HRR

  7. Helminth parasites alter protection against Plasmodium infection.

    Science.gov (United States)

    Salazar-Castañon, Víctor H; Legorreta-Herrera, Martha; Rodriguez-Sosa, Miriam

    2014-01-01

    More than one-third of the world's population is infected with one or more helminthic parasites. Helminth infections are prevalent throughout tropical and subtropical regions where malaria pathogens are transmitted. Malaria is the most widespread and deadliest parasitic disease. The severity of the disease is strongly related to parasite density and the host's immune responses. Furthermore, coinfections between both parasites occur frequently. However, little is known regarding how concomitant infection with helminths and Plasmodium affects the host's immune response. Helminthic infections are frequently massive, chronic, and strong inductors of a Th2-type response. This implies that infection by such parasites could alter the host's susceptibility to subsequent infections by Plasmodium. There are a number of reports on the interactions between helminths and Plasmodium; in some, the burden of Plasmodium parasites increased, but others reported a reduction in the parasite. This review focuses on explaining many of these discrepancies regarding helminth-Plasmodium coinfections in terms of the effects that helminths have on the immune system. In particular, it focuses on helminth-induced immunosuppression and the effects of cytokines controlling polarization toward the Th1 or Th2 arms of the immune response.

  8. Where are the parasites in food webs?

    Directory of Open Access Journals (Sweden)

    Sukhdeo Michael VK

    2012-10-01

    Full Text Available Abstract This review explores some of the reasons why food webs seem to contain relatively few parasite species when compared to the full diversity of free living species in the system. At present, there are few coherent food web theories to guide scientific studies on parasites, and this review posits that the methods, directions and questions in the field of food web ecology are not always congruent with parasitological inquiry. For example, topological analysis (the primary tool in food web studies focuses on only one of six important steps in trematode life cycles, each of which requires a stable community dynamic to evolve. In addition, these transmission strategies may also utilize pathways within the food web that are not considered in traditional food web investigations. It is asserted that more effort must be focused on parasite-centric models, and a central theme is that many different approaches will be required. One promising approach is the old energetic perspective, which considers energy as the critical resource for all organisms, and the currency of all food web interactions. From the parasitological point of view, energy can be used to characterize the roles of parasites at all levels in the food web, from individuals to populations to community. The literature on parasite energetics in food webs is very sparse, but the evidence suggests that parasite species richness is low in food webs because parasites are limited by the quantity of energy available to their unique lifestyles.

  9. Mechanisms of cellular invasion by intracellular parasites.

    Science.gov (United States)

    Walker, Dawn M; Oghumu, Steve; Gupta, Gaurav; McGwire, Bradford S; Drew, Mark E; Satoskar, Abhay R

    2014-04-01

    Numerous disease-causing parasites must invade host cells in order to prosper. Collectively, such pathogens are responsible for a staggering amount of human sickness and death throughout the world. Leishmaniasis, Chagas disease, toxoplasmosis, and malaria are neglected diseases and therefore are linked to socio-economical and geographical factors, affecting well-over half the world's population. Such obligate intracellular parasites have co-evolved with humans to establish a complexity of specific molecular parasite-host cell interactions, forming the basis of the parasite's cellular tropism. They make use of such interactions to invade host cells as a means to migrate through various tissues, to evade the host immune system, and to undergo intracellular replication. These cellular migration and invasion events are absolutely essential for the completion of the lifecycles of these parasites and lead to their for disease pathogenesis. This review is an overview of the molecular mechanisms of protozoan parasite invasion of host cells and discussion of therapeutic strategies, which could be developed by targeting these invasion pathways. Specifically, we focus on four species of protozoan parasites Leishmania, Trypanosoma cruzi, Plasmodium, and Toxoplasma, which are responsible for significant morbidity and mortality.

  10. Where are the parasites in food webs?

    Science.gov (United States)

    2012-01-01

    This review explores some of the reasons why food webs seem to contain relatively few parasite species when compared to the full diversity of free living species in the system. At present, there are few coherent food web theories to guide scientific studies on parasites, and this review posits that the methods, directions and questions in the field of food web ecology are not always congruent with parasitological inquiry. For example, topological analysis (the primary tool in food web studies) focuses on only one of six important steps in trematode life cycles, each of which requires a stable community dynamic to evolve. In addition, these transmission strategies may also utilize pathways within the food web that are not considered in traditional food web investigations. It is asserted that more effort must be focused on parasite-centric models, and a central theme is that many different approaches will be required. One promising approach is the old energetic perspective, which considers energy as the critical resource for all organisms, and the currency of all food web interactions. From the parasitological point of view, energy can be used to characterize the roles of parasites at all levels in the food web, from individuals to populations to community. The literature on parasite energetics in food webs is very sparse, but the evidence suggests that parasite species richness is low in food webs because parasites are limited by the quantity of energy available to their unique lifestyles. PMID:23092160

  11. Blood parasites in reptiles imported to Germany.

    Science.gov (United States)

    Halla, Ursula; Ursula, Halla; Korbel, Rüdiger; Rüdiger, Korbel; Mutschmann, Frank; Frank, Mutschmann; Rinder, Monika; Monika, Rinder

    2014-12-01

    Though international trade is increasing, the significance of imported reptiles as carriers of pathogens with relevance to animal and human health is largely unknown. Reptiles imported to Germany were therefore investigated for blood parasites using light microscopy, and the detected parasites were morphologically characterized. Four hundred ten reptiles belonging to 17 species originating from 11 Asian, South American and African countries were included. Parasites were detected in 117 (29%) of individual reptiles and in 12 species. Haemococcidea (Haemogregarina, Hepatozoon, Schellackia) were found in 84% of snakes (Python regius, Corallus caninus), 20% of lizards (Acanthocercus atricollis, Agama agama, Kinyongia fischeri, Gekko gecko) and 50% of turtles (Pelusios castaneus). Infections with Hematozoea (Plasmodium, Sauroplasma) were detected in 14% of lizards (Acanthocercus atricollis, Agama agama, Agama mwanzae, K. fischeri, Furcifer pardalis, Xenagama batillifera, Acanthosaura capra, Physignathus cocincinus), while those with Kinetoplastea (Trypanosoma) were found in 9% of snakes (Python regius, Corallus caninus) and 25 % of lizards (K. fischeri, Acanthosaura capra, G. gecko). Nematoda including filarial larvae parasitized in 10% of lizards (Agama agama, Agama mwanzae, K. fischeri, Fu. pardalis, Physignathus cocincinus). Light microscopy mostly allowed diagnosis of the parasites' genus, while species identification was not possible because of limited morphological characteristics available for parasitic developmental stages. The investigation revealed a high percentage of imported reptiles being carriers of parasites while possible vectors and pathogenicity are largely unknown so far. The spreading of haemoparasites thus represents an incalculable risk for pet reptiles, native herpetofauna and even human beings.

  12. Parasitism, personality and cognition in fish.

    Science.gov (United States)

    Barber, I; Mora, A B; Payne, E M; Weinersmith, K L; Sih, A

    2017-08-01

    It is well established that parasites can have profound effects on the behaviour of host organisms, and that individual differences in behaviour can influence susceptibility to parasite infections. Recently, two major themes of research have developed. First, there has been a growing interest in the proximate, mechanistic processes underpinning parasite-associated behaviour change, and the interactive roles of the neuro-, immune, and other physiological systems in determining relationships between behaviour and infection susceptibility. Secondly, as the study of behaviour has shifted away from one-off measurements of single behaviours and towards a behavioural syndromes/personality framework, research is starting to focus on the consequences of parasite infection for temporal and contextual consistency of behaviour, and on the implications of different personality types for infection susceptibility. In addition, there is increasing interest in the potential for relationships between cognition and personality to also have implications for host-parasite interactions. As models well-suited to both the laboratory study of behaviour and experimental parasitology, teleost fish have been used as hosts in many of these studies. In this review we provide a broad overview of the range of mechanisms that potentially generate links between fish behaviour, personality, and parasitism, and illustrate these using examples drawn from the recent literature. In addition, we examine the potential interactions between cognition, personality and parasitism, and identify questions that may be usefully investigated with fish models. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Radiation effluent suppression system

    International Nuclear Information System (INIS)

    Watanabe, Atsushi.

    1992-01-01

    In a radiation release suppression system upon accident, an electromotive valve, a pneumatic operation valve or a manual operation valve is disposed to gas ventilation pipelines which are extended from both of a dry well and a wet well of a reactor container to a stuck. In addition, a combination filter of a metal fiber filter made of stainless steel etc. and an activated carbon fiber filter is disposed in the midway of pipelines in a reactor building. With such a constitution, the inside of the container can be depressurized (prevention of ruptures) and the amount of radioactive substances released to circumstances is remarkably suppressed by the effect of radioactive substance capturing effect of the metal fiber filter made of stainless steel etc. disposed in the vent pipe in the container and a radioactive substance capturing effect by the combination filter of the metal fiber filter made of stainless steel, etc. and the activated carbon fiber filter disposed in the gas ventilation pipelines even upon occurrence of an accident exceeding design basis. Systems can be simplified and minimized, and cost down can also be attained. (N.H.)

  14. Planck-suppressed operators

    International Nuclear Information System (INIS)

    Assassi, Valentin; Baumann, Daniel; Green, Daniel; McAllister, Liam

    2014-01-01

    We show that the recent Planck limits on primordial non-Gaussianity impose strong constraints on light hidden sector fields coupled to the inflaton via operators suppressed by a high mass scale Λ. We study a simple effective field theory in which a hidden sector field is coupled to a shift-symmetric inflaton via arbitrary operators up to dimension five. Self-interactions in the hidden sector lead to non-Gaussianity in the curvature perturbations. To be consistent with the Planck limit on local non-Gaussianity, the coupling to any hidden sector with light fields and natural cubic couplings must be suppressed by a very high scale Λ > 10 5 H. Even if the hidden sector has Gaussian correlations, nonlinearities in the mixing with the inflaton still lead to non-Gaussian curvature perturbations. In this case, the non-Gaussianity is of the equilateral or orthogonal type, and the Planck data requires Λ > 10 2 H

  15. Host Diet Affects the Morphology of Monarch Butterfly Parasites.

    Science.gov (United States)

    Hoang, Kevin; Tao, Leiling; Hunter, Mark D; de Roode, Jacobus C

    2017-06-01

    Understanding host-parasite interactions is essential for ecological research, wildlife conservation, and health management. While most studies focus on numerical traits of parasite groups, such as changes in parasite load, less focus is placed on the traits of individual parasites such as parasite size and shape (parasite morphology). Parasite morphology has significant effects on parasite fitness such as initial colonization of hosts, avoidance of host immune defenses, and the availability of resources for parasite replication. As such, understanding factors that affect parasite morphology is important in predicting the consequences of host-parasite interactions. Here, we studied how host diet affected the spore morphology of a protozoan parasite ( Ophryocystis elektroscirrha ), a specialist parasite of the monarch butterfly ( Danaus plexippus ). We found that different host plant species (milkweeds; Asclepias spp.) significantly affected parasite spore size. Previous studies have found that cardenolides, secondary chemicals in host plants of monarchs, can reduce parasite loads and increase the lifespan of infected butterflies. Adding to this benefit of high cardenolide milkweeds, we found that infected monarchs reared on milkweeds of higher cardenolide concentrations yielded smaller parasites, a potentially hidden characteristic of cardenolides that may have important implications for monarch-parasite interactions.

  16. PARASITIC INFECTIONS IN HEMATOPOIETIC STEM CELL TRANSPLANTATION

    Directory of Open Access Journals (Sweden)

    Isidro Jarque

    2016-07-01

    Full Text Available Parasitic infections are rarely documented in hematopoietic stem cell transplant recipients. However, they may be responsible for fatal complications that are only diagnosed at autopsy. Increased awareness of the possibility of parasitic diseases both in autologous and allogeneic stem cell transplant patients is relevant not only for implementing preventive measures but also for performing an early diagnosis and starting appropriate therapy for these unrecognized but fatal infectious complications in hematopoietic transplant recipients. In this review, we will focus on parasitic diseases occurring in this population especially those with major clinical relevance including toxoplasmosis, American trypanosomiasis, leishmaniasis, malaria, and strongyloidiasis, among others, highlighting the diagnosis and management in hematopoietic transplant recipients.

  17. Blood parasites of penguins: a critical review.

    Science.gov (United States)

    Vanstreels, Ralph Eric Thijl; Braga, Érika Martins; Catão-Dias, José Luiz

    2016-07-01

    Blood parasites are considered some of the most significant pathogens for the conservation of penguins, due to the considerable morbidity and mortality they have been shown to produce in captive and wild populations of these birds. Parasites known to occur in the blood of penguins include haemosporidian protozoans (Plasmodium, Leucocytozoon, Haemoproteus), piroplamid protozoans (Babesia), kinetoplastid protozoans (Trypanosoma), spirochete bacteria (Borrelia) and nematode microfilariae. This review provides a critical and comprehensive assessment of the current knowledge on these parasites, providing an overview of their biology, host and geographic distribution, epidemiology, pathology and implications for public health and conservation.

  18. Bacterial and parasitic diseases of parrots.

    Science.gov (United States)

    Doneley, Robert J T

    2009-09-01

    As wild-caught birds become increasingly rare in aviculture, there is a corresponding decline in the incidence of bacterial and parasitic problems and an increase in the recognition of the importance of maintaining health through better nutrition and husbandry. Nevertheless, the relatively close confines of captivity mean an increased pathogen load in the environment in which companion and aviary parrots live. This increased pathogen load leads to greater exposure of these birds to bacteria and parasites, and consequently a greater risk of infection and disease. This article discusses bacterial and parasitic infections in companion and aviary parrots. It includes the origins, pathogens, diagnosis, treatment, and some of the associated risk factors.

  19. Helminth parasites of conventionally mantained laboratory mice

    Directory of Open Access Journals (Sweden)

    Roberto Magalhães Pinto

    1994-03-01

    Full Text Available The spectrum of intestinal parasites present in the SwissWebster, C57B1/6 and DBA/2 mice strains from different animal houses was identified and prevalences compared. Three parasites were observed during the course ofthis study, namely the cestode. Vampirolepis nana (Siebold, 1852 Spasskii, 1954(=Hymenolepis nana and the nematodes Aspiculuris tetraptera (Nitzsch, 1821 Schulz, 1924 and Syphacia obvelata (Rudolphi, 1802 Seurat, 1916. The scope of thisinvestigation has been widened to also include morphometric data on the parasites, to further simplify their identification, since the presence of helminths in laboratory animals is regarded as a restricting factor for the proper attainment of experimental protocols.

  20. Insights into the diversity of eukaryotes in acid mine drainage biofilm communities.

    Science.gov (United States)

    Baker, Brett J; Tyson, Gene W; Goosherst, Lindsey; Banfield, Jillian F

    2009-04-01

    Microscopic eukaryotes are known to have important ecosystem functions, but their diversity in most environments remains vastly unexplored. Here we analyzed an 18S rRNA gene library from a subsurface iron- and sulfur-oxidizing microbial community growing in highly acidic (pH morphological characterization. Results revealed that the populations vary significantly with the habitat and no group is ubiquitous. Surprisingly, many of the eukaryotic lineages (with the exception of the APC) are closely related to neutrophiles, suggesting that they recently adapted to this extreme environment. Molecular analyses presented here confirm that the number of eukaryotic species associated with the acid mine drainage (AMD) communities is low. This finding is consistent with previous results showing a limited diversity of archaea, bacteria, and viruses in AMD environments and suggests that the environmental pressures and interplay between the members of these communities limit species diversity at all trophic levels.

  1. A second pathway to degrade pyrimidine nucleic acid precursors in eukaryotes

    DEFF Research Database (Denmark)

    Andersen, Gorm; Bjornberg, Olof; Polakova, Silvia

    2008-01-01

    Pyrimidine bases are the central precursors for RNA and DNA, and their intracellular pools are determined by de novo, salvage and catabolic pathways. In eukaryotes, degradation of uracil has been believed to proceed only via the reduction to dihydrouracil. Using a yeast model, Saccharomyces kluyv...... of the eukaryotic or prokaryotic genes involved in pyrimidine degradation described to date.......Pyrimidine bases are the central precursors for RNA and DNA, and their intracellular pools are determined by de novo, salvage and catabolic pathways. In eukaryotes, degradation of uracil has been believed to proceed only via the reduction to dihydrouracil. Using a yeast model, Saccharomyces......, respectively. The gene products of URC1 and URC4 are highly conserved proteins with so far unknown functions and they are present in a variety of prokaryotes and fungi. In bacteria and in some fungi, URC1 and URC4 are linked on the genome together with the gene for uracil phosphoribosyltransferase (URC6). Urc1...

  2. Metabolism in anoxic permeable sediments is dominated by eukaryotic dark fermentation

    DEFF Research Database (Denmark)

    Bourke, Michael F.; Marriott, Philip J.; Glud, Ronnie N.

    2017-01-01

    Permeable sediments are common across continental shelves and are critical contributors to marine biogeochemical cycling. Organic matter in permeable sediments is dominated by microalgae, which as eukaryotes have different anaerobic metabolic pathways to prokaryotes such as bacteria and archaea....... Here we present analyses of flow-through reactor experiments showing that dissolved inorganic carbon is produced predominantly as a result of anaerobic eukaryotic metabolic activity. In our experiments, anaerobic production of dissolved inorganic carbon was consistently accompanied by large dissolved H....../hydrogenase pathway of fermentative eukaryotic H2 production, suggesting that pathway as the source of H2 and dissolved inorganic carbon production. Metabolomic analysis showed large increases in lipid production at the onset of anoxia, consistent with documented pathways of anoxic dark fermentation in microalgae...

  3. Large-scale analysis of phosphorylation site occupancy in eukaryotic proteins

    DEFF Research Database (Denmark)

    Rao, R Shyama Prasad; Møller, Ian Max

    2012-01-01

    in proteins is currently lacking. We have therefore analyzed the occurrence and occupancy of phosphorylated sites (~ 100,281) in a large set of eukaryotic proteins (~ 22,995). Phosphorylation probability was found to be much higher in both the  termini of protein sequences and this is much pronounced...... maximum randomness. An analysis of phosphorylation motifs indicated that just 40 motifs and a much lower number of associated kinases might account for nearly 50% of the known phosphorylations in eukaryotic proteins. Our results provide a broad picture of the phosphorylation sites in eukaryotic proteins.......Many recent high throughput technologies have enabled large-scale discoveries of new phosphorylation sites and phosphoproteins. Although they have provided a number of insights into protein phosphorylation and the related processes, an inclusive analysis on the nature of phosphorylated sites...

  4. Initiation of translation in bacteria by a structured eukaryotic IRES RNA.

    Science.gov (United States)

    Colussi, Timothy M; Costantino, David A; Zhu, Jianyu; Donohue, John Paul; Korostelev, Andrei A; Jaafar, Zane A; Plank, Terra-Dawn M; Noller, Harry F; Kieft, Jeffrey S

    2015-03-05

    The central dogma of gene expression (DNA to RNA to protein) is universal, but in different domains of life there are fundamental mechanistic differences within this pathway. For example, the canonical molecular signals used to initiate protein synthesis in bacteria and eukaryotes are mutually exclusive. However, the core structures and conformational dynamics of ribosomes that are responsible for the translation steps that take place after initiation are ancient and conserved across the domains of life. We wanted to explore whether an undiscovered RNA-based signal might be able to use these conserved features, bypassing mechanisms specific to each domain of life, and initiate protein synthesis in both bacteria and eukaryotes. Although structured internal ribosome entry site (IRES) RNAs can manipulate ribosomes to initiate translation in eukaryotic cells, an analogous RNA structure-based mechanism has not been observed in bacteria. Here we report our discovery that a eukaryotic viral IRES can initiate translation in live bacteria. We solved the crystal structure of this IRES bound to a bacterial ribosome to 3.8 Å resolution, revealing that despite differences between bacterial and eukaryotic ribosomes this IRES binds directly to both and occupies the space normally used by transfer RNAs. Initiation in both bacteria and eukaryotes depends on the structure of the IRES RNA, but in bacteria this RNA uses a different mechanism that includes a form of ribosome repositioning after initial recruitment. This IRES RNA bridges billions of years of evolutionary divergence and provides an example of an RNA structure-based translation initiation signal capable of operating in two domains of life.

  5. The reduced kinome of Ostreococcus tauri: core eukaryotic signalling components in a tractable model species.

    Science.gov (United States)

    Hindle, Matthew M; Martin, Sarah F; Noordally, Zeenat B; van Ooijen, Gerben; Barrios-Llerena, Martin E; Simpson, T Ian; Le Bihan, Thierry; Millar, Andrew J

    2014-08-02

    The current knowledge of eukaryote signalling originates from phenotypically diverse organisms. There is a pressing need to identify conserved signalling components among eukaryotes, which will lead to the transfer of knowledge across kingdoms. Two useful properties of a eukaryote model for signalling are (1) reduced signalling complexity, and (2) conservation of signalling components. The alga Ostreococcus tauri is described as the smallest free-living eukaryote. With less than 8,000 genes, it represents a highly constrained genomic palette. Our survey revealed 133 protein kinases and 34 protein phosphatases (1.7% and 0.4% of the proteome). We conducted phosphoproteomic experiments and constructed domain structures and phylogenies for the catalytic protein-kinases. For each of the major kinases families we review the completeness and divergence of O. tauri representatives in comparison to the well-studied kinomes of the laboratory models Arabidopsis thaliana and Saccharomyces cerevisiae, and of Homo sapiens. Many kinase clades in O. tauri were reduced to a single member, in preference to the loss of family diversity, whereas TKL and ABC1 clades were expanded. We also identified kinases that have been lost in A. thaliana but retained in O. tauri. For three, contrasting eukaryotic pathways - TOR, MAPK, and the circadian clock - we established the subset of conserved components and demonstrate conserved sites of substrate phosphorylation and kinase motifs. We conclude that O. tauri satisfies our two central requirements. Several of its kinases are more closely related to H. sapiens orthologs than S. cerevisiae is to H. sapiens. The greatly reduced kinome of O. tauri is therefore a suitable model for signalling in free-living eukaryotes.

  6. (macro- Evolutionary ecology of parasite diversity: From determinants of parasite species richness to host diversification

    Directory of Open Access Journals (Sweden)

    Serge Morand

    2015-04-01

    Full Text Available The present review summarized the factors or determinants that may explain parasite diversity among host species and the consequences of this parasite diversity on the evolution of host-life history traits. As host–parasite interactions are asymmetrical exploited–exploiter relationships, ecological and epidemiological theories produce hypotheses to find the potential determinants of parasite species richness, while life-history theory helps for testing potential consequences on parasite diversity on the evolution of hosts. This review referred only to studies that have specifically controlled or took into account phylogenetic information illustrated with parasites of mammals. Several points needing more investigation were identified with a special emphasis to develop the metabolic theory of epidemiology.

  7. Reduced helminth parasitism in the introduced bank vole (Myodes glareolus: More parasites lost than gained

    Directory of Open Access Journals (Sweden)

    Karen C. Loxton

    2016-08-01

    Full Text Available Introduced species are often less parasitised compared to their native counterparts and to ecologically similar hosts in the new environment. Reduced parasitism may come about due to both the loss of original parasites and low acquisition of novel parasites. In this study we investigated the intestinal helminth parasites of the introduced bank vole (Myodes glareolus in Ireland. Results were compared to data from other European studies and to the intestinal helminth fauna of an ecologically similar native rodent in Ireland, the wood mouse (Apodemus sylvaticus. The helminth fauna of introduced bank voles exhibited low diversity with only 3 species recovered: Aspiculuris tianjinensis; Aonchotheca murissylvatici and Taenia martis larvae. In particular, no adult parasites with indirect life-cycles were found in bank voles suggesting that indirectly transmitted parasites are less likely to establish in invasive hosts. Also, the results of this study add support to the enemy release hypothesis.

  8. Revisiting the Relationship between Transposable Elements and the Eukaryotic Stress Response.

    Science.gov (United States)

    Horváth, Vivien; Merenciano, Miriam; González, Josefa

    2017-11-01

    A relationship between transposable elements (TEs) and the eukaryotic stress response was suggested in the first publications describing TEs. Since then, it has often been assumed that TEs are activated by stress, and that this activation is often beneficial for the organism. In recent years, the availability of new high-throughput experimental techniques has allowed further interrogation of the relationship between TEs and stress. By reviewing the recent literature, we conclude that although there is evidence for a beneficial effect of TE activation under stress conditions, the relationship between TEs and the eukaryotic stress response is quite complex. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Comparative radiobiology of genetic loci of eukaryots as the basis of the general theory of mutations

    International Nuclear Information System (INIS)

    Aleksandrov, I.D.

    1983-01-01

    One of the fundamental problems of modern molecular cellular radiobiology is to reveal general and peculiar processes of the formation of gene mutations and chromosome aberrations in each stage of their formation in the irradiated genome of the higher eukaryots. The solution of the problems depends on the development of research within the framework of comparative radiobiology of genetic loci of the higher eukaryots that makes it possible to study quantitative regularities in the formation of gene (point) mutations and chromosome aberrations in one object and in the same experiment

  10. Once in a lifetime: strategies for preventing re-replication in prokaryotic and eukaryotic cells

    DEFF Research Database (Denmark)

    Nielsen, Olaf; Løbner-Olesen, Anders

    2008-01-01

    DNA replication is an extremely accurate process and cells have evolved intricate control mechanisms to ensure that each region of their genome is replicated only once during S phase. Here, we compare what is known about the processes that prevent re-replication in prokaryotic and eukaryotic cells...... prokaryotes and eukaryotes are inactivated until the next cell cycle. Furthermore, in both systems the beta-clamp of the replicative polymerase associates with enzymatic activities that contribute to the inactivation of the helicase loaders. Finally, recent studies suggest that the control mechanism...

  11. Signaling mechanisms of apoptosis-like programmed cell death in unicellular eukaryotes.

    Science.gov (United States)

    Shemarova, Irina V

    2010-04-01

    In unicellular eukaryotes, apoptosis-like cell death occurs during development, aging and reproduction, and can be induced by environmental stresses and exposure to toxic agents. The essence of the apoptotic machinery in unicellular organisms is similar to that in mammals, but the apoptotic signal network is less complex and of more ancient origin. The review summarizes current data about key apoptotic proteins and mechanisms of the transduction of apoptotic signals by caspase-like proteases and mitochondrial apoptogenic proteins in unicellular eukaryotes. The roles of receptor-dependent and receptor-independent caspase cascades are reviewed. 2010 Elsevier Inc. All rights reserved.

  12. Eukaryotic RNA polymerase subunit RPB8 is a new relative of the OB family.

    Science.gov (United States)

    Krapp, S; Kelly, G; Reischl, J; Weinzierl, R O; Matthews, S

    1998-02-01

    RNA polymerase II subunit RPB8 is an essential subunit that is highly conserved throughout eukaryotic evolution and is present in all three types of nuclear RNA polymerases. We report the first high resolution structural insight into eukaryotic RNA polymerase architecture with the solution structure of RPB8 from Saccharomyces cerevisiae. It consists of an eight stranded, antiparallel beta-barrel, four short helical regions and a large, unstructured omega-loop. The strands are connected in classic Greek-key fashion. The overall topology is unusual and contains a striking C2 rotational symmetry. Furthermore, it is most likely a novel associate of the oligonucleotide/oligosaccharide (OB) binding protein class.

  13. Deep sequencing-based transcriptome analysis of Plutella xylostella larvae parasitized by Diadegma semiclausum

    Science.gov (United States)

    2011-01-01

    Background Parasitoid insects manipulate their hosts' physiology by injecting various factors into their host upon parasitization. Transcriptomic approaches provide a powerful approach to study insect host-parasitoid interactions at the molecular level. In order to investigate the effects of parasitization by an ichneumonid wasp (Diadegma semiclausum) on the host (Plutella xylostella), the larval transcriptome profile was analyzed using a short-read deep sequencing method (Illumina). Symbiotic polydnaviruses (PDVs) associated with ichneumonid parasitoids, known as ichnoviruses, play significant roles in host immune suppression and developmental regulation. In the current study, D. semiclausum ichnovirus (DsIV) genes expressed in P. xylostella were identified and their sequences compared with other reported PDVs. Five of these genes encode proteins of unknown identity, that have not previously been reported. Results De novo assembly of cDNA sequence data generated 172,660 contigs between 100 and 10000 bp in length; with 35% of > 200 bp in length. Parasitization had significant impacts on expression levels of 928 identified insect host transcripts. Gene ontology data illustrated that the majority of the differentially expressed genes are involved in binding, catalytic activity, and metabolic and cellular processes. In addition, the results show that transcription levels of antimicrobial peptides, such as gloverin, cecropin E and lysozyme, were up-regulated after parasitism. Expression of ichnovirus genes were detected in parasitized larvae with 19 unique sequences identified from five PDV gene families including vankyrin, viral innexin, repeat elements, a cysteine-rich motif, and polar residue rich protein. Vankyrin 1 and repeat element 1 genes showed the highest transcription levels among the DsIV genes. Conclusion This study provides detailed information on differential expression of P. xylostella larval genes following parasitization, DsIV genes expressed in the

  14. Immunological responses to parasitic arthropods.

    Science.gov (United States)

    Baron, R W; Weintraub, J

    1987-03-01

    Parasitic arthropods are responsible for enormous economic losses to livestock producers throughout the world. These production losses may range from simple irritation caused by biting and non-biting flies to deaths and/or damage to carcass, fleece, or skin resulting from attack by myiasis flies. The estimated costs of these losses are colossal but even these usually include only direct losses and ignore those associated with pesticide application. In the USA alone (in 1976), these losses were conservatively estimated at more than 650 million US dollars. The long term use of chemical control measures for these pests has resulted in many serious problems including residues in meat and milk products, rapid development of insecticide resistance, the destruction of non-target organisms, environmental pollution, and mortality and morbidity of livestock. These concerns have prompted researchers to seek alternative methods of arthropod control, including the artificial induction of immunity. In this review, R. W. Baron and J. Weintraub discuss several examples of ectoparasites that can induce immunological resistance in the host, including Sarcoptes and Demodex mites, the sheep ked (Melophagus ovinus), Anopluran lice and myiasis-causing flies such as Hypoderma.

  15. Parasite specialization in a unique habitat: hummingbirds as reservoirs of generalist blood parasites of Andean birds.

    Science.gov (United States)

    Moens, Michaël A J; Valkiūnas, Gediminas; Paca, Anahi; Bonaccorso, Elisa; Aguirre, Nikolay; Pérez-Tris, Javier

    2016-09-01

    Understanding how parasites fill their ecological niches requires information on the processes involved in the colonization and exploitation of unique host species. Switching to hosts with atypical attributes may favour generalists broadening their niches or may promote specialization and parasite diversification as the consequence. We analysed which blood parasites have successfully colonized hummingbirds, and how they have evolved to exploit such a unique habitat. We specifically asked (i) whether the assemblage of Haemoproteus parasites of hummingbirds is the result of single or multiple colonization events, (ii) to what extent these parasites are specialized in hummingbirds or shared with other birds and (iii) how hummingbirds contribute to sustain the populations of these parasites, in terms of both prevalence and infection intensity. We sampled 169 hummingbirds of 19 species along an elevation gradient in Southern Ecuador to analyse the host specificity, diversity and infection intensity of Haemoproteus by molecular and microscopy techniques. In addition, 736 birds of 112 species were analysed to explore whether hummingbird parasites are shared with other birds. Hummingbirds hosted a phylogenetically diverse assemblage of generalist Haemoproteus lineages shared with other host orders. Among these parasites, Haemoproteus witti stood out as the most generalized. Interestingly, we found that infection intensities of this parasite were extremely low in passerines (with no detectable gametocytes), but very high in hummingbirds, with many gametocytes seen. Moreover, infection intensities of H. witti were positively correlated with the prevalence across host species. Our results show that hummingbirds have been colonized by generalist Haemoproteus lineages on multiple occasions. However, one of these generalist parasites (H. witti) seems to be highly dependent on hummingbirds, which arise as the most relevant reservoirs in terms of both prevalence and

  16. Parasitic myoma after supracervical laparoscopic histerectomy

    Directory of Open Access Journals (Sweden)

    Maurício Paulo Angelo Mieli

    2013-06-01

    Full Text Available Parasitic myoma is a condition defined as a myoma of extrauterine nourishing. It may occur spontaneously or as a consequence of surgical iatrogeny, after myomectomy or videolaparoscopic supracervical hysterectomy, due to remaining residues of uterine tissue fragments in the pelvic cavity after morcellation. The authors describe two cases in which the patients were submitted to videolaparoscopic supracervical hysterectomy and uterine body removal through morcellation. The sites of development of the parasitic myomas were next to the cervix stump in Case 1, and next to the right round ligament in Case 2. These parasitic myomas were removed by videolaparoscopy. After myomectomies or videolaparoscopic supracervical hysterectomies followed by uterine fragments removal from the pelvic cavity through morcellation, meticulous searching for residues or fragments of uterine tissue is mandatory to prevent the occurrence of parasitic myomas.

  17. Mammalian gastrointestinal parasites in rainforest remnants of ...

    Indian Academy of Sciences (India)

    2015-04-27

    Apr 27, 2015 ... parasite recovery by sucrose floatation and sedimentation techniques ..... We thank the Chief Wildlife Warden,Tamil Nadu Forest. Department ... disease is a strong and general service of biodiversity conservation: Response ...

  18. Molecular characterization of intestinal protozoan parasites from ...

    African Journals Online (AJOL)

    Koffi Mathurin

    2014-02-17

    Feb 17, 2014 ... three major protozoan parasites which cause diarrhea. Out of ... 2010) regarding the under 5 mortality rate (U5MR) and .... Positive (%) Negative Total ..... Checkley W, Epstein LD, Gilman RH, Black RE, Cabrera L, Sterling CR.

  19. Identifying energy constraints to parasite resistance.

    Science.gov (United States)

    Allen, D E; Little, T J

    2011-01-01

    Life-history theory suggests that energetically expensive traits may trade off against each other, resulting in costs associated with the development or maintenance of a particular phenotype. The deployment of resistance mechanisms during parasite exposure is one such trait, and thus their potential benefit in fighting off parasites may be offset by costs to other fitness-related traits. In this study, we used trade-off theory as a basis to test whether stimulating an increased development rate in juvenile Daphnia would reveal energetic constraints to its ability to resist infection upon subsequent exposure to the castrating parasite, Pasteuria ramosa. We show that the presumably energetically expensive process of increased development rate does result in more infected hosts, suggesting that parasite resistance requires the allocation of resources from a limited source, and thus has the potential to be costly.

  20. Ant parasite queens revert to mating singly

    DEFF Research Database (Denmark)

    Sumner, Seirian; Hughes, William Owen Hamar; Pedersen, Jes Søe

    2004-01-01

    quantified and they tend to be similar in related species. Here we compare the mating strategies of the leaf-cutting ant Acromyrmex echinatior and its recently derived social parasite Acromyrmex insinuator, which is also its closest relative 2 (see Fig. 1 ). We find that although the host queens mate with up......A parasitic ant has abandoned the multiple mating habit of the queens of its related host. Multiple mating (polyandry) is widespread among animal groups, particularly insects 1 . But the factors that maintain it and underlie its evolution are hard to verify because benefits and costs are not easily...... to a dozen different males, the social parasite mates only singly. This rapid and surprising reversion to single mating in a socially parasitic ant indicates that the costs of polyandry are probably specific to a free-living lifestyle....