104 Baruch, D.I., Pasloske, B.L., Singh, H.B., Bi, X.H., Ma, X.C., Feldman, M., Taraschi, T.F., and Howar d, R.J. (1995). Cloning the Plasmodium falciparum gene encoding Pfemp1, a malarial variant antigen and adherence receptor on the surface of parasitized human erythrocytes Cell 82, 7787. Bock, R., Jackson, L., de Vos, A., and Jorgensen, W. (2004). Babesiosis of cattle. Parasitology 129 Suppl S247269. Borst, P., Bitter, W., Blundell, P.A., Chaves, I., Cross, M., Gerrits, H., van Leeuwen, F., McCulloch, R., Taylor, M., and Rudenko, G. (1998). Control of VSG gene expression sites in Trypanosoma brucei Mol Biochem Parasitol 91 6776. Borst, P., and Ulbert, S. (2001). Control of VSG gene expression sites. Molecular and Biochemical Parasitology 114, 1727. Brayton, K.A., Lau, A.O.T., Herndon, D.R., Hannick, L., Kappmeyer, L.S., Berens, S.J., Bidwell, S.L., Br own, W.C., Crabtree, J., Fadrosh, D., et al. (2007). Genome sequence of B abesia bovis and comparative analysis of apicomplexan hemoprotozoa. ...
2nd International Workshop on Foundations of Coordination Languages and Software Architectures (Foclasa 2002) September 2, 2003, Marseille, France Workshop affiliated to CONCUR2003, 02 - 06 September 2003. http://www.info.fundp.ac.be/~jmj/Foclasa03.html ====================================================================== SCOPE AND TOPICS Modern information systems rely more and more on combining concurrent, distributed, mobile and heterogenous components. This move from old systems, typically conceived in isolation, induces the need for new languages and software architectures. In particular, coordination languages have been proposed to cleanly separate computational aspects and communication. On the other hand, software architects face the problem of specifying and reasoning on non-functional requirements. All these issues are widely perceived as fundamental to improve software productivity, enhance maintainability, advocate modularity, promote reusability, and lead to systems more tractable ...
Production of gametocytes by asexually dividing parasites is a selective disadvantage. Inducible recombination allows controlled expression of ap2-g and
Matrajt, M.; Donald, R.G.K.; Singh, U.; Roos, D.S., 2002: Identification and characterization of differentiation mutants in the protozoan parasite Toxoplasma gondii
We have an immediate opening for a Post-doctoral Scientist to work on a Leishmania genome sequencing project at Seattle Biomedical Research Institute. We have recently received NIH funding to sequence 10-20 Mb of the Leishmania genome over the next 5 years. Leishmania is a protozoan parasite with a total genome size of 36 Mb, spread over 36 chromosomes. Specific duties will include cloning, template prep, mapping, sequencing, analysis, and supervision of several research technicians. Experiences with database development and genome informatics will be essential, and familiarity with MS Access and Visual Basic would be an advantage. SBRI is an Equal Opportunity Employer and offers a full benefit package. Interested parties should send a resume via e-mail, FAX or mail to: Peter J. Myler, Ph.D. Seattle Biomedical Research Institute 4 Nickerson Street Seattle, WA 98109-1651 e-mail: mylerpj at sbri.org Phone: (206)-284-8846x332 FAX: (206)-284-0313 -- ======================================= Peter J. ...
Citation: Dubey, J.P. 2013. The history and life cycle of Toxoplasma gondii. In: Weiss, L.M. and Kim, K., editors. Toxoplasma gondii, The model apicomplexan: Perspective and methods. 2nd edition. Waltham, MA: Elsevier. p. 1-14. Interpretive Summary: Toxoplasma gondii is a single-celled parasite of all warm-blooded hosts worldwide. It causes mental retardation and loss of vision in children, and abortion in livestock. Cats are the main reservoir of T. gondii because they are the only hosts that can excrete the resistant stage (oocyst) of the parasite in the feces. Humans become infected by eating under cooked meat from infected animals and food and water contaminated with oocysts. In the present paper the author reviews life cycle of Toxoplasma. The results will be of interest to biologists, parasitologists, and public health workers. Technical Abstract: Infections by the protozoan parasite Toxoplasma gondii are widely prevalent in humans and other animals on all continents. There are many ...
Trypanosoma brucei, a causative agent of African sleeping sickness in humans and nagana in animals, constantly changes its dense variant surface glycoprotein (VSG) coat to avoid elimination by the immune system of its mammalian host, using an extensive repertoire of dedicated genes. Although this process, referred to as antigenic variation, is the major mechanism of pathogenesis for T. brucei, the dynamics of VSG expression in T. brucei during an infection are poorly understood. In this thesis, I describe the development of VSG-seq, a method for quantitatively examining the diversity of expressed VSGs in any population of trypanosomes. Using VSG-seq, I monitored VSG expression dynamics in vivo during both acute and chronic mouse infections. My experiments revealed unexpected diversity within parasite populations, and the expression of as much as one-third of the functional genomic VSG repertoire after only one month of infection. In addition to suggesting that the host-pathogen interaction in T.
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Autophagy is a eukaryotic catabolic pathway that degrades and recycles cellular components to maintain homeostasis. It can target protein aggregates, superfluous biomolecular complexes, dysfunctional and damaged organelles, as well as pathogenic intracellular microbes. Autophagy is a dynamic process in which the different stages from initiation to final degradation of cargo are finely regulated. Therefore, the study of this process requires the use of a palette of techniques, which are continuously evolving and whose interpretation is not trivial. Here, we present the social amoeba Dictyostelium discoideum as a relevant model to study autophagy. Several methods have been developed based on the tracking and observation of autophagosomes by microscopy, analysis of changes in expression of autophagy genes and proteins, and examination of the autophagic flux with various techniques. In this review, we discuss the pros and cons of the currently available techniques to assess autophagy in this organism.
Macroautophagy is a mechanism employed by eukaryotic cells to recycle non-essential cellular components during starvation, differentiation, and development. Two conjugation reactions related to ubiquitination are essential for autophagy: Apg12p conjugation to Apg5p, and Apg8p conjugation to the lipid phosphatidylethanolamine. These reactions require the action of the E1-like enzyme, Apg7p, and the E2-like enzymes, Apg3p and Apg10p. In Dictyostelium, development is induced by starvation, conditions under which autophagy is required for survival in yeast and plants. We have identified Dictyostelium homologues of 10 budding yeast autophagy genes. We have generated mutations in apg5 and apg7 that produce defects typically associated with an abrogation of autophagy. Mutants are not grossly affected in growth, but survival during nitrogen starvation is severely reduced. Starved mutant cells show little turnover of cellular constituents by electron microscopy, whereas wild-type cells show significant ...
Females in various species typically avoid males infected with parasites, while parasite-free males advertise their status through conspicuous phenotypic traits. This process selects for heritable resistance and reduces direct exposure of the female to parasites. Coevolving parasites are likely to attempt to circumvent this obstacle. In this paper, we demonstrate a case of parasitic manipulation of host mate choice. We report that Toxoplasma gondii, a sexually transmitted infection of brown rats, enhances sexual attractiveness of infected males. Thus under some evolutionary niches, parasites can indeed manipulate host sexual signaling to their own advantage ...
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I recently wondered, in response to an ideas paper in BioEssays, whether animals, fungi, slime moulds etc. actually had a multicellular common ancestor. Dickinson and colleagues argument (partly) hinged on the shared presence of epithelia, barrier cell layers with distinct insides and outsides, in animals and the social amoeba Dictyostelium discoideum. The most recent crop…
Just as water molecules spontaneously arrange to form geometric snowflakes, the â socialâ amoeba Dictyostelium discoideum transitions from a collection of unicellular organisms to a fruiting body during its life cycle. This aggregation is guided by cyclic AMP (cAMP): when stimulated with cAMP, cells respond by producing and secreting more of the molecule, which, once levels reach a threshold, results in nondissipating waves of cAMP and collective amoeba movement.. Published by Learning Registry #GoOpen. 2 Views, 0 Likes on Docs.com. #Cyclic AMP #NSDL_SetSpec_BEN #nondissipating waves #unicellular organisms #amoeba
The UK/EU Dicty Christmas Meeting 2014 took place on 17th and 18th December in Somerville College, Oxford. Researchers from all over the UK, coming as far afield as Dundee and Cambridge, gathered to discuss a diverse range of biological features of the social amoeba Dictyostelium discoideum. The meeting also attracted delegates from Europe with…
Tetrahymena thermophila ATCC ® 30383™ Designation: B-18686 Isolation: derived from WH-6 X WH-14, Urbana, IL, early 1950s
At the end of this unit, the student is able to:  Classify the Protozoans  Describe the morphology of each protozoa  Explain the pathophysiology, life cycle…
Human malaria is a devastating disease and a major cause of poverty in resource-limited countries. To develop and adapt within hosts Plasmodium falciparum undergoes drastic switches in gene expression. To identify regulatory regions in the parasite genome, we performed genome-wide profiling of chromatin accessibility in two culture-adapted isogenic subclones at four developmental stages during the intraerythrocytic cycle by using the Assay for Transposase-Accessible Chromatin by sequencing (ATAC-seq). Tn5 transposase hypersensitivity sites (THSSs) localize preferentially at transcriptional start sites (TSSs). Chromatin accessibility by ATAC-seq is predictive of active transcription and of the levels of histone marks H3K9ac and H3K4me3. Our assay allows the identification of novel regulatory regions including TSS and enhancer-like elements. We show that the dynamics in the accessible chromatin profile matches temporal transcription during development. Motif analysis of stage-specific ATAC-seq ...
The mature erythrocyte is a terminally differentiated, nonendocytic cell in nature. Membrane invagination is uncommon in mature healthy erythrocytes. However, these cells are readily invaded by malaria parasites, which involute the red cell1,2 to generate a host-derived parasitophorous vacuolar membrane (PVM). This process is central to the establishment of the blood-stage infection that is responsible for all symptoms and pathologies of this major human disease.3. Recently, we and others have shown that erythrocytes contain detergent-resistant membranes (DRMs).4⇓⇓⇓⇓⇓-10 These highly buoyant, lipid-rich complexes have also been isolated from various other cell types and appear to be enriched for proteins and lipids present in lipid rafts of cellular membranes. The leading definition of membrane rafts suggests that they may consist of small dynamic domains in the plasma membrane stabilized by cholesterol11 and in response to various stimuli coalesce into a larger, less mobile zone, as ...
Vaccination with live attenuated parasites has been shown to induce high level of protection against Toxoplasma gondii. In this study we compared the Mic1-3KO tachyzoite (a live attenuated strain) with the parental wild type (WT) tachyzoite in terms of virulence in mice in vivo, dissemination in mouse tissues and persistence in mouse brain. Survival of mice infected with the Mic1-3KO parasites correlated with reduced parasite burden in mouse tissues compared to the parental strain. Like the WT parasite, Mic1-3KO is able to form tissue cysts in vivo which are not, in our experimental conditions, infectious when given by oral route. Infection with the attenuated tachyzoite induced lower levels of cytokine and chemokine than with the parental strain. These data demonstrate that the deleted strain derived from a type I strain behaves like type II strain in outbred mice in terms of virulence, dissemination in mouse tissue and persistence in brain ...
Finding an immune system in the social amoeba (Dictyostelium discoideum) is not only surprising but it also may prove a clue as to what is necessary for an organism to become multicellular, said the Baylor College of Medicine ...
The obligate intracellular protozoan parasite Toxoplasma gondii infects humans and other warm-blooded animals and establishes a chronic infection in the central nervous system after invasion. Studies showing a positive correlation between anti-Toxopl
Due to its central role in both evolutionary change and human disease, mutation has been the focus of intensive research. The probability that a spontaneous mut...
Quadrulus membranelle (4 rows of cilia) in the buccal cavity of Paramecium tetraurelia. Microtubules of the axonemes of the cilia and the triplet fibe...
Information on this disease caused by the protozoan parasite Toxoplasma gondii, its life cycle, the symptoms, diagnosis, treatment, public health significance and prevention. ...
A high resolution view of a median longitudinal section through this collecting canal that may be artificially swollen at two sites where it is encirc...
Looking for antigenic variation? Find out information about antigenic variation. Alteration of an antigen on the surface of a microorganism; may enable a pathogenic mocroorganism to evade destruction by the hosts immune system Explanation of antigenic variation
Κάτοχος Φρούτου: Ellefson Suruperasus Όνομα Φρούτου: Purutotaipu Purutotaipu No Mi Τύπος Φρούτου: Paramecia Αναλυτική Περιγραφή Φρούτου: Είναι ένα υπερβολικά
Copyright 2013 by the Massachusetts General Hospital. Some sections copyright 2008-2009 by The President and Fellows of Harvard College.. ...
Molecular genetic studies of the human malaria parasite Plasmodium falciparum have been hampered in part due to difficulties in stably cloning and propagating parasite genomic DNA in bacteria. This is thought to be a result of the unusual A+T bias (|80%) in the parasites DNA. Pulsed-field gel electrophoretic separation of P. falciparum chromosomes has shown that large chromosomal polymorphisms, resulting from the deletion of DNA from chromosome ends, frequently occur. Understanding the biological implications of this chromosomal polymorphism will require the analysis of large regions of genomic, and in particular telomeric, DNA. To overcome the limitations of cloning parasite DNA in bacteria, we have cloned genomic DNA from the P. falciparum strain FCR3 in yeast as artificial chromosomes. A pYAC4 library with an average insert size of approximately 100 kb was established and found to have a three to fourfold redundancy for single-copy genes. Unlike bacterial hosts, yeast stably maintain and propagate
Ciliated protozoan (Tetrahymena vorax), coloured scanning electron micrograph (SEM). Tetrahymena vorax is a fresh water, holotrichous, oligohymenophoran, ciliate. Shown here are 3 cells with nice ciliated pellicle surfaces. Tetrahymena are free-living ciliated protozoa that can switch from commensalistic to pathogenic modes of survival. They are common in freshwater ponds. Tetrahymena species are used as model organisms. Magnification: x260 when shortest axis printed at 25 millimetres. - Stock Image C032/0976
In general, the cellular structure of T. brucei is similar to all other eukaryotes. There are however, a few differences. T. bruceis cell surface has, (in addition to its surface antigens), a thick layer of proteins, called Variant Surface Glycoprotein (VSGs) genes. These allow the surface antigens to mutate, by switching variants.(2) Having over 1000 VSG genes and psuedogenes, T. brucei is able to switch variants frequently. Trascription occurs one gene at a time, from one of many telomeric VSG expression sites.(3) In order to switch an active VSG gene, DNA rearrangements must occur, to switch the old VSG gene with a new one. Using the bloodstream form of T. brucei, scientists in the Netherlands discovered that telomere exchange, thought to be rare, was indeed occuring. The scientists marked a VSG gene with a hygromycin resistance gene, allowed the gene to undergo variation, and selected switched Trypanosomes. The drug sensitivity and polymerase chain reactions (PCR), revealed that telomere ...
Surprisingly, our ML analyses indicate that the distribution of mutational effects in T. thermophila is best approximated by the equal effects model (shape parameter, β → ∞). An alternative explanation is that the distribution of mutational effects is complex (e.g., a bimodal distribution including a high probability of slightly deleterious mutations and a second peak of moderately deleterious mutations) and not well approximated by any gamma distribution (Davies et al. 1999; Halligan and Keightley 2009). These hypotheses could be tested by repeating the multiple GE analysis for more MA lines, which would allow us to estimate the variance in mutational effects (Vs) directly.. In a survey of MA studies, Halligan and Keightley (2009) noted that the dominance of new mutations has been studied only in a handful of organisms and is not well understood even in those. Therefore, estimates in additional organisms are valuable. Our estimate of the average dominance coefficient of new mutations (h = ...
Hemozoin is generally considered a waste deposit that is formed for the sole purpose of detoxification of free heme that results from the digestion of hemoglobin by Plasmodium parasites. However, several observations of parasite multiplication, both in vertebrate and invertebrate hosts are suggestive of a wider, but overlooked, metabolic role for this product. The presence of clinical peripheral blood samples of P. falciparum with high parasitemia containing only hemozoin-deficient (non-pigmented) asexual forms has been repeatedly confirmed. Such samples stand in contrast with other samples that contain mostly pigmented circulating trophozoites and gametocytes, indicating that pigment accumulation is a prominent feature of gametocytogenesis. The restricted size, i.e. below detection by light microscopy, of hemozoin in asexual merozoites and ringforms of P. falciparum implies its continuous turnover, supporting a role in metabolism. The prominent interaction of hemozoin with several antimalarial ...
... POSITION Biochemistry, Microbiology, Drug development Indiana University School of Medicine POSTDOCTORAL POSITION available to investigate the efficacy and mechanism of experimental drugs to treat infection caused by the protozoan parasite Toxoplasma gondii. Related to the malaria parasite, Toxoplasma causes birth defects and life-threatening infection in immunocompromised AIDS or heart transplant patients. The successful candidate will continue the … Continue reading. ...
Evolution had a few more drinks once again, according to a new paper in Proceedings of the National Academy of Sciences which wants to prompts a rethink of what it means to be an animal.
Biology Assignment Help, Heliozoans - protozoan, Heliozoans - Protozoan Heliozoans are spherical protozoan that occur in the sea or in still bodies of fresh water. They are mainly located in the bottom debris. Fine needle like pseudopodia radiate from the surface of the body. These are known a
Browse the database consisting of PfEMP1 from seven P. falciparum genomes (3D7, DD2, HB3, IT4, PFCLIN, IGH, RAJ116) and related proteins (see reference below for details). Press submit to see all proteins with all homology blocks, or filter output by filling one or more fields below ...
Genetic investigations of malaria require a genome-wide, high-resolution linkage map of Plasmodium falciparum. A genetic cross was used to construct such a map from 901 markers that fall into 14 inferred linkage groups corresponding to the 14 nuclear chromosomes. Meiotic crossover activity in the genome proved high (17 kilobases per centimorgan) and notably uniform over chromosome length. Gene conversion events and spontaneous microsatellite length changes were evident in the inheritance data. The markers, map, and recombination parameters are facilitating genome sequence assembly, localization of determinants for such traits as virulence and drug resistance, and genetic studies of parasite field populations. ...
The relationship between cytoplasmic pH (pHi) and prestalk/prespore differentiation in the cellular slime mould Dictyostelium discoideum was investigated by: (1) comparing the pHi of prestalk and prespore cells, and (2) examining the effects on pHi of weak acids, weak bases and proton-pump inhibitors. These substances are known to affect the spore-to-stalk ratio. The pHj of dissociated slug cells was measured by microfluorometry using a pH-sensitive fluorescence dye, carboxyfluorescein.. There was a slight but significant difference in pH, between prestalk cells (7.38 ± 0.09) and prespore cells (7.49 ± 0.03), and prestalk cells were more sensitive to acid load than prespore cells. In addition, weak acids and proton-pump inhibitors, which promote prestalk differentiation, significantly lowered pHi whereas weak bases, which induce prespore differentiation, elevated pHi. However, differentiation inducing factor (DIF), an endogenous inducer of stalk differentiation, caused only a slight and ...
Bifunctional enzyme. Involved in de novo dTMP biosynthesis. Key enzyme in folate metabolism. Catalyzes an essential reaction for de novo glycine and purine synthesis, DNA precursor synthesis, and for the conversion of dUMP to dTMP (By similarity).
The traditional view of RNA being merely an intermediate in the transfer of genetic information, as mRNA, spliceosomal RNA, tRNA, and rRNA, has become outdated. The recent discovery of numerous regulatory RNAs with a plethora of functions in biological processes has truly revolutionized our understanding of gene regulation. Tiny RNAs such as microRNAs and small interfering RNAs play vital roles at different levels of gene control. Small nucleolar RNAs are much more abundant than previously recognized, and new functions beyond processing and modification of rRNA have recently emerged. Longer non-coding RNAs (ncRNAs) can also have important regulatory roles in the cell, e.g., antisense RNAs that control their target mRNAs. The majority of these important findings arose from analyses in various model organisms. In this review, we focus on ncRNAs in the social amoeba Dictyostelium discoideum. This important genetically tractable model organism has recently received renewed attention in terms of ...
Antigenic variation by variant surface glycoprotein (VSG) coat switching in African trypanosomes is one of the most elaborate immune evasion strategies found among pathogens. Changes in the identity of the transcribed VSG gene, which is always flanked by 70-bp and telomeric repeats, can be achieved either by transcriptional or DNA recombination mechanisms. The major route of VSG switching is DNA recombination, which occurs in the bloodstream VSG expression site (ES), a multigenic site transcribed by RNA polymerase I. Recombinogenic VSG switching is frequently catalyzed by homologous recombination (HR), a reaction normally triggered by DNA breaks. However, a clear understanding of how such breaks arise-including whether there is a dedicated and ES-focused mechanism-is lacking. Here, we synthesize data emerging from recent studies that have proposed a range of mechanisms that could generate these breaks: action of a nuclease or nucleases; repetitive DNA, most notably the 70-bp repeats, providing ...
TY - CHAP. T1 - Bradyzoite Development. AU - Knoll, Laura J.. AU - Tomita, Tadakimi. AU - Weiss, Louis M.. PY - 2013/9/1. Y1 - 2013/9/1. N2 - Once the acute phase of Toxoplasma gondii infection resolves, the parasite remains latent as bradyzoite forms that persist within tissue cysts. The stress-induced conversion of tachyzoites to bradyzoites is a critical step in pathogenesis of toxoplasmosis, because latent bradyzoite forms can reactivate with waning immune function and are infectious to other hosts. Despite their biological importance, the biology of bradyzoites and the molecular mechanisms for developmental transition are not well understood. Bradyzoites express unique antigens and metabolic enzymes and are encased within a highly glycosylated cyst wall, This chapter reviews our progress in understanding unique structural components of bradyzoite cysts and the signalling processes that lead to T. gondii persistence.. AB - Once the acute phase of Toxoplasma gondii infection resolves, the ...
Lien vers Pubmed [PMID] - 22100161. Cell Host Microbe 2011 Nov;10(5):451-63. Many microbial pathogens, including the malaria parasite Plasmodium falciparum, vary surface protein expression to evade host immune responses. P. falciparium antigenic variation is linked to var gene family-encoded clonally variant surface protein expression. Mututally exclusive var gene expression is partially controlled by spatial positioning; silent genes are retained at distinct perinuclear sites and relocated to transcriptionally active locations for monoallelic expression. We show that var introns can control this process and that var intron addition relocalizes episomes from a random to a perinuclear position. This var intron-regulated nuclear tethering and repositioning is linked to an 18 bp nuclear protein-binding element that recruits an actin protein complex. Pharmacologically induced F-actin formation, which is restricted to the nuclear periphery, repositions intron-carrying episomes and var genes and ...
A model is developed and used to study within-human malaria parasite dynamics. The model integrates actors involved in the development-progression of parasitemia, gametocytogenesis and mechanisms for...
High resolution image of the macronucleus which contains microtubules that lie inside a seemingly intact nuclear envelope. Microtubules orient along t...
Dictyostelium discoideum PIK1 protein: similar to phosphatidylinositide 3-kinases; regulate endosomal pathway; isolated from Dictyostelium discoideum; amino acid sequence in first source
David Lloyd, Catrin F. Williams Diplomonads: both harmless free-living protozoa and important parasites Single-cells with paired nuclei and....
Bekijk Stockfoto van Didinium Is A Predatory Protozoan That Feeds Primarily On Paramecium Sem X800. Ga voor hoogwaardige fotos met een hoge resolutie naar Getty Images.