Comparative analysis of the kinomes of three pathogenic trypanosomatids: Leishmania major, Trypanosoma brucei and Trypanosoma cruzi

BACKGROUND: The trypanosomatids Leishmania major, Trypanosoma brucei and Trypanosoma cruzi cause some of the most debilitating diseases of humankind: cutaneous leishmaniasis, African sleeping sickness, and Chagas disease. These protozoa possess complex life cycles that involve development in mammalian and insect hosts, and a tightly coordinated cell cycle ensures propagation of the highly polarized cells. However, the ways in which the parasites respond to their environment and coordinate intracellular processes are poorly understood. As a part of an effort to understand parasite signaling functions, we report the results of a genome-wide analysis of protein kinases (PKs) of these three trypanosomatids. RESULTS: Bioinformatic searches of the trypanosomatid genomes for eukaryotic PKs (ePKs) and atypical PKs (aPKs) revealed a total of 176 PKs in T. brucei, 190 in T. cruzi and 199 in L. major, most of which are orthologous across the three species. This is approximately 30% of the number in the human host and double that of the malaria parasite, Plasmodium falciparum. The representation of various groups of ePKs differs significantly as compared to humans: trypanosomatids lack receptor-linked tyrosine and tyrosine kinase-like kinases, although they do possess dual-specificity kinases. A relative expansion of the CMGC, STE and NEK groups has occurred. A large number of unique ePKs show no strong affinity to any known group. The trypanosomatids possess few ePKs with predicted transmembrane domains, suggesting that receptor ePKs are rare. Accessory Pfam domains, which are frequently present in human ePKs, are uncommon in trypanosomatid ePKs. CONCLUSION: Trypanosomatids possess a large set of PKs, comprising approximately 2% of each genome, suggesting a key role for phosphorylation in parasite biology. Whilst it was possible to place most of the trypanosomatid ePKs into the seven established groups using bioinformatic analyses, it has not been possible to ascribe function based solely on sequence similarity. Hence the connection of stimuli to protein phosphorylation networks remains enigmatic. The presence of numerous PKs with significant sequence similarity to known drug targets, as well as a large number of unusual kinases that might represent novel targets, strongly argue for functional analysis of these molecules

Functional Identification Of A Leishmania Gene Related To The Peroxin 2 Gene Reveals Common Ancestry Of Glycosomes And Peroxisomes

Glycosomes are membrane-bounded microbody organelles that compartmentalize glycolysis as well as other important metabolic processes in trypanosomatids, The compartmentalization of these enzymatic reactions is hypothesized to play a crucial role in parasite physiology, Although the metabolic role of glycosomes differs substantially from that of the peroxisomes that are found in other eukaryotes, similarities in signals targeting proteins to these organelles suggest that glycosomes and peroxisomes may have evolved from a common ancestor, To examine this hypothesis, as well as gain insights into the function of the glycosome, we used a positive genetic selection procedure to isolate the first Leishmania mutant (gim1-1 [glycosome import] mutant) with a defect in the import of glycosomal proteins, The mutant retains glycosomes but mislocalizes a subset glycosomal proteins to the cytoplasm, Unexpectedly, the gim1-1 mutant lacks lipid bodies, suggesting a heretofore unknown role of the glycosome. We used genetic approaches to identify a gene, GIM1, that is able to restore import and lipid bodies, A nonsense mutation was found in one allele of this gene in the mutant line, The predicted Gim1 protein is related the peroxin 2 family of integral membrane proteins, which are required for peroxisome biogenesis, The similarities in sequence and function provide strong support for the common origin model of glycosomes and peroxisomes. The novel phenotype of gim1-1 and distinctive role of Leishmania glycosomes suggest that future studies of this system will provide a new perspective on microbody biogenesis and function

Widespread variation in transcript abundance within and across developmental stages of Trypanosoma brucei

<p>Abstract</p> <p>Background</p> <p><it>Trypanosoma brucei</it>, the causative agent of African sleeping sickness, undergoes a complex developmental cycle that takes place in mammalian and insect hosts and is accompanied by changes in metabolism and cellular morphology. While differences in mRNA expression have been described for many genes, genome-wide expression analyses have been largely lacking. Trypanosomatids represent a unique case in eukaryotes in that they transcribe protein-coding genes as large polycistronic units, and rarely regulate gene expression at the level of transcription initiation.</p> <p>Results</p> <p>Here we present a comprehensive analysis of mRNA expression in several stages of parasite development. Utilizing microarrays that have multiple copies of multiple probes for each gene, we were able to demonstrate with a high degree of statistical confidence that approximately one-fourth of genes show differences in mRNA expression levels in the stages examined. These include complex patterns of gene expression within gene families, including the large family of variant surface glycoproteins (VSGs) and their relatives, where we have identified a number of constitutively expressed family members. Furthermore, we were able to assess the relative abundance of all transcripts in each stage, identifying the genes that are either weakly or highly expressed. Very few genes show no evidence of expression.</p> <p>Conclusion</p> <p>Despite the lack of gene regulation at the level of transcription initiation, our results reveal extensive regulation of mRNA abundance associated with different life cycle and growth stages. In addition, analysis of variant surface glycoprotein gene expression reveals a more complex picture than previously thought. These data provide a valuable resource to the community of researchers studying this lethal agent.</p

Trouble with the edTPA: Sliding from Teaching to Preparing for the Test

This paper was written by a group of instructors responsible for preparing 100 elementary/middle school licensure students for the edTPA portfolio assessment. It is an analysis of our experiences doing so in the pilot year. The edTPA is a performance assessment required for teacher licensure. We considered this assessment to have significant advantages over a multiple choice test and we debated for a year how best to implement it. Our plan was to integrate what they needed to know into our courses rather than to prepare them directly for the test. We approached this with a positive attitude but emerged with a skeptical one. We gradually slid from preparing students to be teachers, to preparing them for the test. Using a narrative self-study, we chronicle and analyze this unexpected trajectory

NADH dehydrogenase of Trypanosoma brucei is important for efficient acetate production in bloodstream forms

This work was supported by a grant from the National Institutes of Health (USA) [AI 5R01 AI069057] to MP and AS; a grant from the Medical Research Council (UK) [G0600129] to AS; grants from the Centre National de la Recherche Scientifique (CNRS, France), The Université de Bordeaux, The Agence Nationale de la Recherche (ANR) [ACETOTRYP of the ANR-BLANC-2010 call and GLYCONOV of the “Générique” call] and the Laboratoire d’Excellence (LabEx) ParaFrap [grant ANR-11-LABX-0024] to FB; and a grant from the Wellcome Trust [093228] to TKS.In the slender bloodstream form, Trypanosoma brucei mitochondria are repressed for many functions. Multiple components of mitochondrial complex I, NADH:ubiquinone oxidoreductase, are expressed in this stage, but electron transfer through complex I is not essential. Here we investigate the role of the parasite’s second NADH:ubiquinone oxidoreductase, NDH2, which is composed of a single subunit that also localizes to the mitochondrion. While inducible knockdown of NDH2 had a modest growth effect in bloodstream forms, NDH2 null mutants, as well as inducible knockdowns in a complex I deficient background, showed a greater reduction in growth. Altering the NAD+/NADH balance would affect numerous processes directly and indirectly, including acetate production. Indeed, loss of NDH2 led to reduced levels of acetate, which is required for several essential pathways in bloodstream form T. brucei and which may have contributed to the observed growth defect. In conclusion our study shows that NDH2 is important, but not essential, in proliferating bloodstream forms of T. brucei, arguing that the mitochondrial NAD+/NADH balance is important in this stage, even though the mitochondrion itself is not actively engaged in the generation of ATP.Publisher PDFPeer reviewe

The Ursinus Weekly, May 3, 1954

Jack Westerhoff elected assistant head waiter • Y officers begin duties at retreat • Honor system advances • Meistersingers present last scheduled concert • Tilton Barron to transfer to Clark Univ. • Pi Gamma Mu honors 11 with membership • The real Man who came • May Day festivities will be held this Saturday • Eugene P. Bertin spoke to F.T.A. • Dr. Rice presents model O train display in Library • Band will present twilight concert at Ursinus May Day • Rosicrucians elect officers for 1954-55 • Your obligation • Letter to the editor • Pre-med story • Average student • Professor says • Collegeville-Trappe story: Today • Batsmen still roll on glory road; Track injuries plague Eshbach, Ruth • Bryn Mawr defeats tennisettes by 3-2 • UC Varsity Club to fete outstanding senior athlete • Ehlers edges powerful Delaware, 2-1: Art wins 4th on 7 hitter; Slotter hurls 3rd shutout • Brodbeck I, Curtis II softballers lead interdorm diamond pack • Racketgals cop 5-0 court win in straight sets • Albright falls tennis victim to Ursinus, 6-3 • Lehigh takes 12 firsts; Crush tracksters 92-33https://digitalcommons.ursinus.edu/weekly/1496/thumbnail.jp

Integrative analysis of the Trypanosoma brucei gene expression cascade predicts differential regulation of mRNA processing and unusual control of ribosomal protein expression

Background: Trypanosoma brucei is a unicellular parasite which multiplies in mammals (bloodstream form) and Tsetse flies (procyclic form). Trypanosome RNA polymerase II transcription is polycistronic, individual mRNAs being excised by trans splicing and polyadenylation. We previously made detailed measurements of mRNA half-lives in bloodstream and procyclic forms, and developed a mathematical model of gene expression for bloodstream forms. At the whole transcriptome level, many bloodstream-form mRNAs were less abundant than was predicted by the model. Results: We refined the published mathematical model and extended it to the procyclic form. We used the model, together with known mRNA half-lives, to predict the abundances of individual mRNAs, assuming rapid, unregulated mRNA processing; then we compared the results with measured mRNA abundances. Remarkably, the abundances of most mRNAs in procyclic forms are predicted quite well by the model, being largely explained by variations in mRNA decay rates and length. In bloodstream forms substantially more mRNAs are less abundant than predicted. We list mRNAs that are likely to show particularly slow or inefficient processing, either in both forms or with developmental regulation. We also measured ribosome occupancies of all mRNAs in trypanosomes grown in the same conditions as were used to measure mRNA turnover. In procyclic forms there was a weak positive correlation between ribosome density and mRNA half-life, suggesting cross-talk between translation and mRNA decay; ribosome density was related to the proportion of the mRNA on polysomes, indicating control of translation initiation. Ribosomal protein mRNAs in procyclics appeared to be exceptionally rapidly processed but poorly translated. Conclusions: Levels of mRNAs in procyclic form trypanosomes are determined mainly by length and mRNA decay, with some control of precursor processing. In bloodstream forms variations in nuclear events play a larger role in transcriptome regulation, suggesting aquisition of new control mechanisms during adaptation to mammalian parasitism

The Iowa Homemaker vol.33, no.4

An American Task, Dr. Paul Sharp, page 7 Pizza, Doris Jirsa, page 8 International Social Whirl, Ann Lindemeyer, page 9 Enchanting Paris, Else Nielsen, page 10 New Foods and Flavors, Dorothy Will, page 11 Costa Rican Friendships, Margaret Cole, page 12 A Debt Is Due, Marilyn Heu and Lillian Nakamota, page 13 Information Please, Rachel Bernau and Margaret Mattison, page 14 Overseas Jobs for YOU, Kay Scholten, page 15 Food for the Male, Pat Stiff, page 16 An Invitation to the U. N. Tea, Jane Hammerly, page 17 A.H.E.A. Ambassadors, Harriet Parsons, page 18 Nationally Speaking, Dorothy Will, page 19 What’s New, page 20 Trends, Gwen Owen, page 2

Two essential Thioredoxins mediate apicoplast biogenesis, protein import, and gene expression in Toxoplasma gondii.

Apicomplexan parasites are global killers, being the causative agents of diseases like toxoplasmosis and malaria. These parasites are known to be hypersensitive to redox imbalance, yet little is understood about the cellular roles of their various redox regulators. The apicoplast, an essential plastid organelle, is a verified apicomplexan drug target. Nuclear-encoded apicoplast proteins traffic through the ER and multiple apicoplast sub-compartments to their place of function. We propose that thioredoxins contribute to the control of protein trafficking and of protein function within these apicoplast compartments. We studied the role of two Toxoplasma gondii apicoplast thioredoxins (TgATrx), both essential for parasite survival. By describing the cellular phenotypes of the conditional depletion of either of these redox regulated enzymes we show that each of them contributes to a different apicoplast biogenesis pathway. We provide evidence for TgATrx1's involvement in ER to apicoplast trafficking and TgATrx2 in the control of apicoplast gene expression components. Substrate pull-down further recognizes gene expression factors that interact with TgATrx2. We use genetic complementation to demonstrate that the function of both TgATrxs is dependent on their disulphide exchange activity. Finally, TgATrx2 is divergent from human thioredoxins. We demonstrate its activity in vitro thus providing scope for drug screening. Our study represents the first functional characterization of thioredoxins in Toxoplasma, highlights the importance of redox regulation of apicoplast functions and provides new tools to study redox biology in these parasites

Debating Technology for Dialogical Argument:Sensemaking, Engagement and Analytics

Debating technologies, a newly emerging strand of research into computational technologies to support human debating, offer a powerful way of providing naturalistic, dialogue-based interaction with complex information spaces. The full potential of debating technologies for dialogical argument can, however, only be realized once key technical and engineering challenges are overcome, namely data structure, data availability, and interoperability between components. Our aim in this article is to show that the Argument Web, a vision for integrated, reusable, semantically rich resources connecting views, opinions, arguments, and debates online, offers a solution to these challenges. Through the use of a running example taken from the domain of citizen dialogue, we demonstrate for the first time that different Argument Web components focusing on sensemaking, engagement, and analytics can work in concert as a suite of debating technologies for rich, complex, dialogical argument