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- Arai, M, et al.
(författare)
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Both mosquito-derived xanthurenic acid and a host blood-derived factor regulate gametogenesis of Plasmodium in the midgut of the mosquito
- 2001
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Ingår i: Molecular and biochemical parasitology (Print). - : Elsevier. - 0166-6851 .- 1872-9428. ; 116:1, s. 17-24
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Tidskriftsartikel (refereegranskat)abstract
- Gametogenesis of Plasmodium in vitro can be induced by the combined stimulus of a 5 degrees C fall in temperature and the presence of xanthurenic acid (XA). In-vitro experiments showed that P. gallinaceum (EC(50)=80 nM) is much more sensitive to XA than P. berghei (9 microM), P. yoelii (8 microM), and P. falciparum (2 microM). However, in the mosquito vector, we do not know whether the temperature shift and XA are the only gametocyte-activating factors (GAF), nor do we know with certainty the true source(s) of XA in the mosquito blood meal. Previous studies indicate that XA is the only source of GAF in the mosquito. By defining, and then contrasting, the ability of an XA-deficient mutant of Aedes aegypti, with the wild-type mosquito to support exflagellation and ookinete formation in vivo, we determined the roles of parasite-, mosquito- and host blood-derived GAF in the regulation of gametogenesis of P. gallinaceum. Removal of both host and vector sources of GAF totally inhibited both exflagellation and ookinete production, whilst the lack of either single source resulted in only a partial reduction of exflagellation and ookinete formation in the mosquito gut. Both sources can be effectively replaced/substituted by synthetic XA. This suggests (1) both mosquito- and vertebrate-derived factors act as GAF in the mosquito gut in vivo; (2) the parasite itself is unable to produce any significant GAF activity. Studies are underway to determine whether vertebrate-derived GAF is XA. These data may form the basis of further studies of the development of new methods of interrupting malarial transmission.
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- Fusai, T, et al.
(författare)
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Characterisation of the chondroitin sulphate of Saimiri brain microvascular endothelial cells involved in Plasmodium falciparum cytoadhesion
- 2000
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Ingår i: Molecular and biochemical parasitology (Print). - 0166-6851 .- 1872-9428. ; 108:1, s. 25-37
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Tidskriftsartikel (refereegranskat)abstract
- Cytoadhesion of Plasmodium falciparum-infected erythrocytes (IRBC) to chondroitin-4-sulphate (CSA) is inhibited by soluble CSA in vitro on Saimiri brain microvascular endothelial cells (SBEC) and in vivo in P. falciparum-infected Saimiri monkeys. We tested whether the SBEC model was appropriate for studying CSA-binding IRBC using four cell lines. All SBEC expressed a chondroitin sulphate (CS), with a composition of CSA. The mean sizes of these CSA were 20.5, 22, 23, 32.5 and 36 kDa for SBEC 3A and C2, CHO, SBEC 1D and 17, respectively. We found that cytoadhesion of the Palo-Alto (FUP)1 CSA-binding phenotype, selected by panning on SBEC 17, was specifically inhibited in a dose-dependent manner by all the purified CSA. The extent of inhibition depended on the cellular origin of the tested CSA. SBEC 17 CSA was 33 times more efficient than CHO-CSA and 21 times more efficient than the 50 kDa commercial bovine trachaea CSA. Dynabeads coated with a total extract of SBEC 1D CS-proteoglycans interacted with CSA- but not with CD36- or ICAM-1-binding IRBC. These Dynabeads also interacted specifically with the PfEMP1 DBL-3 domain, on the surface of CHO transfectants, but not with the CIDR-1 domain. Thrombomodulin was involved in IRBC adhesion to all SBEC whereas CD44 was only expressed by SBEC 1D and 17. These two CSA-proteoglycans have also been detected at the surface of human endothelial cells. Thus, the two homologous models, SBEC/Saimiri sciureus, are useful and reliable tools for the evaluation of new anti-CSA adhesion treatments and anti-disease vaccines for pregnant women.
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- Henriksson, Jan, et al.
(författare)
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Chromosome specific markers reveal conserved linkage groups in spite of extensive chromosomal size variation in Trypanosoma cruzi
- 1995
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Ingår i: Molecular and biochemical parasitology (Print). - 0166-6851 .- 1872-9428. ; 73:1-2, s. 63-74
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Tidskriftsartikel (refereegranskat)abstract
- The karyotypes of three cloned stocks, CL Brener (CL), CA I/72 (CA) and Sylvio X10/7 (X10), of Trypanosoma cruzi were studied by pulsed-field gel electrophoresis followed by ethidium bromide staining and hybridization with 35 different probes, 30 of which identified single chromosomes. The chromosome-specific probes identified between 26 and 31 chromosomal bands in the three cloned stocks, corresponding to 20 unique chromosomes in CL and 19 in CA and X10. Considering the DNA content of the parasite, it was predicted that the markers recognise at least half of all T. cruzi chromosomes. A majority of identified chromosomes showed large differences in size among different strains, in some cases by up to 50%. Interestingly, CL had in general larger chromosomes than the two other studied cloned stocks. Several of the markers showed linkage and nine different linkage groups were identified, each comprising 2-4 markers. The linkage between the markers was maintained in 8 of the 9 linkage groups when a panel comprising 26 different T. cruzi strains representing major T. cruzi populations was tested. One linkage group was found to be maintained in some strains but not in others. This result shows that chromosomal rearrangements occur in the T. cruzi genome, albeit with a low frequency. Repetitive DNA, both non-coding and in one case coding, was more abundant in the cloned stock CL Brener than in CA and X10. The information presented will make it possible to select chromosomes for the construction of physical chromosomal maps required for the T. cruzi genome project.
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