Wednesday, May 13, 2009

What's new for 'Trypanosomatids' in PubMed

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Search kinetoplastids OR kinetoplastid OR Kinetoplastida OR "trypanosoma brucei" OR leishmania OR brucei OR leishmaniasis OR "African trypanosomiasis"
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PubMed Results
Items 1 -6 of 6

1: PLoS Negl Trop Dis. 2009;3(5):e435. Epub 2009 May 12.

Prospects for Developing Odour Baits To Control Glossina fuscipes spp., the Major Vector of Human African Trypanosomiasis.

Omolo MO, Hassanali A, Mpiana S, Esterhuizen J, Lindh J, Lehane MJ, Solano P, Rayaisse JB, Vale GA, Torr SJ, Tirados I.

International Center for Insect Physiology and Ecology, ICIPE, Nairobi, Kenya.

We are attempting to develop cost-effective control methods for the important vector of sleeping sickness, Glossina fuscipes spp. Responses of the tsetse flies Glossina fuscipes fuscipes (in Kenya) and G. f. quanzensis (in Democratic Republic of Congo) to natural host odours are reported. Arrangements of electric nets were used to assess the effect of cattle-, human- and pig-odour on (1) the numbers of tsetse attracted to the odour source and (2) the proportion of flies that landed on a black target (1x1 m). In addition responses to monitor lizard (Varanus niloticus) were assessed in Kenya. The effects of all four odours on the proportion of tsetse that entered a biconical trap were also determined. Sources of natural host odour were produced by placing live hosts in a tent or metal hut (volumes approximately 16 m(3)) from which the air was exhausted at approximately 2000 L/min. Odours from cattle, pigs and humans had no significant effect on attraction of G. f. fuscipes but lizard odour doubled the catch (P<0.05). Similarly, mammalian odours had no significant effect on landing or trap entry whereas lizard odour increased these responses significantly: landing responses increased significantly by 22% for males and 10% for females; the increase in trap efficiency was relatively slight (5-10%) and not always significant. For G. f. quanzensis, only pig odour had a consistent effect, doubling the catch of females attracted to the source and increasing the landing response for females by approximately 15%. Dispensing CO(2) at doses equivalent to natural hosts suggested that the response of G. f. fuscipes to lizard odour was not due to CO(2). For G. f. quanzensis, pig odour and CO(2) attracted similar numbers of tsetse, but CO(2) had no material effect on the landing response. The results suggest that identifying kairomones present in lizard odour for G. f. fuscipes and pig odour for G. f. quanzensis may improve the performance of targets for controlling these species.

PMID: 19434232 [PubMed - in process]

2: Infect Immun. 2009 May 11. [Epub ahead of print]

Over-expression of the natural inhibitor of cysteine peptidases, ICP, in Leishmania mexicana leads to reduced virulence and a Th1 response.

Bryson K, Besteiro S, McGachy HA, Coombs GH, Mottram JC, Alexander J.

Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, The John Arbuthnott Building, 27 Taylor St, Glasgow G4 ONR, United Kingdom; Wellcome Centre for Molecular Parasitology and Division of Infection & Immunity, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow G12 8TA, United Kingdom.

Leishmania mexicana cysteine peptidases (CPs) have been identified as important parasite virulence factors. More recently a natural inhibitor of CPs (ICP) from L. mexicana has been characterised and ICP mutants have been created. Infection of BALB/c mice with ICP null mutants or ICP re-expressing mutants resulted in non-healing progressively growing lesions albeit slightly attenuated compared with the growth of wild-type parasites. In contrast BALB/c mice infected with mutants over-expressing ICP were able to significantly control lesion growth or heal. While BALB/c mice infected with wild-type parasites, ICP null mutants or ICP re-expressing mutants produced significant antibody responses including IgE, no Th1 response as indicated by antigen-induced splenocyte IFN-gamma production could be demonstrated. In contrast, BALB/c mice infected with mutants over-expressing ICP produced significantly less antibody, particularly IgE, as well as significantly reduced splenocyte IL-4, and enhanced IFN-gamma production. BALB/c mice were able to resolve infection following infection with one ICP over-expressing clone, which was subsequently used for vaccination studies in BALB/c mice. However, no protection was afforded these mice when they were challenged with wild-type parasites. Nevertheless, 2 other mouse strains susceptible to L. mexicana, C3H and C57BL/6, vaccinated with over-expressing ICP mutants were able to control challenge infection associated with an enhanced Th1 response. This study confirms that L. mexicana CPs are virulence factors and that ICPs have therapeutic potential.

PMID: 19433541 [PubMed - as supplied by publisher]

3: Acta Trop. 2009 May 8. [Epub ahead of print]

Stimulation of Leishmania tropica protein kinase CK2 activities by platelet-activating factor (PAF).

Dutra PM, Vieira DP, Meyer-Fernandes JR, Silva-Neto MA, Lopes AH.

Disciplina de Parasitologia, DPL, FCM, Universidade do Estado do Rio de Janeiro, Rua Prof. Manoel de Abreu, 444, PAPC 5 degrees andar, Vila Isabel, Rio de Janeiro, 20550-170, Brazil.

Leishmania tropica is one of the causative agents of cutaneous leishmaniasis. Platelet-activating factor (PAF) is a phospholipid mediator in diverse biological and pathophysiological processes. Here we show that PAF promoted a three-fold increase on ecto-protein kinase and a three-fold increase on the secreted kinase activity of L. tropica live promastigotes. When casein was added to the reaction medium, along with PAF, there was a four-fold increase on the ecto-kinase activity. When live L. tropica promastigotes were pre-incubated for 30min in the presence of PAF plus casein, a six-fold increase on the secreted kinase activity was observed. Also, a protein released from L. tropica promastigotes reacted with polyclonal antibodies for the mammalian CK2 alpha catalytic subunit. Furthermore, in vitro mouse macrophage infection by L. tropica was doubled when promastigotes were pre-treated for two hours with PAF. Similar results were obtained when the interaction was performed in the presence of purified CK2 or casein. TBB and DRB, CK2 inhibitors, reversed PAF enhancement of macrophage infection by L. tropica. WEB 2086, a competitive PAF antagonist, reversed all PAF effects here described. This study shows for the first time that PAF promotes the activation of two isoforms of CK2, secreted and membrane-bound, correlating these activities to infection of mouse macrophages.

PMID: 19433049 [PubMed - as supplied by publisher]

4: BMC Microbiol. 2009 May 11;9(1):90. [Epub ahead of print]

Evaluation of high efficiency gene knockout strategies for Trypanosoma cruzi.

Xu D, Brandan CP, Basombrio MA, Tarleton RL.

ABSTRACT: BACKGROUND: Trypanosoma cruzi, a kinetoplastid protozoan parasite that causes Chagas disease, infects approximately 15 million people in Central and South America. In contrast to the substantial in silico studies of the T. cruzi genome, transcriptome, and proteome, only a few genes have been experimentally characterized and validated, mainly due to the lack of facile methods for gene manipulation needed for reverse genetic studies. Current strategies for gene disruption in T. cruzi are tedious and time consuming. In this study we have compared the conventional multi-step cloning technique with two knockout strategies that have been proven to work in other organisms, one-step-PCR- and Multisite Gateway-based systems. RESULTS: While the one-step-PCR strategy was found to be the fastest method for production of knockout constructs, it does not efficiently target genes of interest using gene-specific sequences of less than 80 nucleotides. Alternatively, the Multisite Gateway based approach is less time-consuming than conventional methods and is able to efficiently and reproducibly delete target genes. CONCLUSIONS: Using the Multisite Gateway strategy, we have rapidly produced constructs that successfully produce specific gene deletions in epimastigotes of T. cruzi. This methodology should greatly facilitate reverse genetic studies in T. cruzi.

PMID: 19432966 [PubMed - as supplied by publisher]

5: Mol Biochem Parasitol. 2009 May;165(1):19-31. Epub 2009 Jan 15.Click here to read LinkOut

Homology, paralogy and function of DGF-1, a highly dispersed Trypanosoma cruzi specific gene family and its implications for information entropy of its encoded proteins.

Kawashita SY, da Silva CV, Mortara RA, Burleigh BA, Briones MR.

Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, São Paulo, SP, Brazil.

Surface adhesion proteins are essential for Trypanosoma cruzi invasion of mammalian cells. Here we show that Dispersed Gene Family-1 (DGF-1) members, previously identified as nuclear repeated sequences present in several chromosomes and comprising the third largest T. cruzi specific gene family, have conserved adhesin motifs including four segments with significant similarity to human beta 7 integrin. Flow cytometry and biotinylation assays with anti-DGF-1 antibodies indicated that, as expected, DGF-1 members are expressed on the trypomastigote surface. The DGF-1 genealogy, inferred using T. cruzi Genome Project data and network phylogeny algorithms, suggests that this gene family is separated in at least three groups with differential distribution of functional domains. To identify which members of this gene family are expressed we used a combined approach of RT-PCR and codon usage profiles, showing that expressed members have a very biased codon usage favoring GC, whereas non-expressed members have a homogeneous distribution. Shannon information entropy was used to measure sequence variability and revealed four major high entropy segments in the extracellular domain of DGF-1 overlapping with important putative functional modules of the predicted proteins. Testing for natural selection, however, indicated that these high entropy segments were not under positive selection, which contradicts the notion that positive selection is the cause of high variability in specific domains of a protein relative to other less variable regions in the same molecule. We conjectured that members of the DGF-1 family might be associated with the ability of T. cruzi to bind extracellular matrix proteins, such as fibronectin and laminin, and speculated on mechanisms that would be generating the localized diversity in these molecules in the absence of selection.

PMID: 19393159 [PubMed - indexed for MEDLINE]

6: Biochem Biophys Res Commun. 2009 Apr 24;382(1):30-4. Epub 2009 Feb 24.Click here to read LinkOut

Proteomic analysis of the Trypanosoma cruzi ribosomal proteins.

Ayub MJ, Atwood J, Nuccio A, Tarleton R, Levin MJ.

Laboratorio de Biología Molecular de la Enfermedad de Chagas, Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI-CONICET), Buenos Aires, Argentina.

Trypanosoma cruzi is a parasite responsible for Chagas disease. The identification of new targets for chemotherapy is a major challenge for the control of this disease. Several lines of evidences suggest that the translational system in trypanosomatids show important differences compared to other eukaryotes. However, there little is known information about this. We have performed a detailed data mining search for ribosomal protein genes in T. cruzi genome data base combined with mass spectrometry analysis of purified T. cruzi ribosomes. Our results show that T. cruzi ribosomal proteins have approximately 50% sequence identity to yeast ones. Nevertheless, some parasite proteins are longer due to the presence of several N- or C-terminal extensions, which are exclusive of trypanosomatids. In particular, L19 and S21 show C-terminal extensions of 168 and 164 amino acids, respectively. In addition, we detected two 60S subunit proteins that had not been previously detected in the T. cruzi total proteome; namely, L22 and L42.

PMID: 19245787 [PubMed - indexed for MEDLINE]

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