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11.
Marsollier L Aubry J Coutanceau E André JP Small PL Milon G Legras P Guadagnini S Carbonnelle B Cole ST 《Cellular microbiology》2005,7(7):935-943
Mycobacterium ulcerans was first identified as the causative agent of Buruli ulcer; this cutaneous tissue-destructive process represents the third most important mycobacterial disease in humans after tuberculosis and leprosy. More recently other life traits were documented. M. ulcerans is mainly detected in humid tropical zones as part of a complex ecosystem comprising algae, aquatic insect predators of the genus Naucoris, and very likely their vegetarian preys. Coelomic plasmatocytes could be the first cells of Naucoris cimicoides to be involved in the infection process, acting as shuttle cells that deliver M. ulcerans to the salivary glands as suggested by both in vitro and in vivo approaches. Furthermore, a key element for the early and long-term establishment of M. ulcerans in Naucoridae is demonstrated by the fact that only mycolactone toxin-producing M. ulcerans isolates are able to invade the salivary glands, a site where they proliferate. Later, the raptorial legs of Naucoris are covered by M. ulcerans-containing material that displays features of biofilms. 相似文献
12.
Margaret?O?Nwagwu Helen?Baines Jeffrey?B?Kerr Francis?JP?EblingEmail author 《Reproductive biology and endocrinology : RB&E》2005,3(1):48
Background
Testicular development is arrested in the hypogonadal (hpg) mouse due to a congenital deficiency in hypothalamic gonadotropin-releasing hormone (GnRH) synthesis. Chronic treatment of male hpg mice with estradiol induces FSH synthesis and secretion, and causes testicular maturation and qualitatively normal spermatogenesis. As estradiol negative feedback normally inhibits FSH production in the male, this study tested whether this paradoxical response to estradiol in the male hpg mouse might be due to inadequate masculinisation or incomplete defeminization in the neonatal period. Previous studies have demonstrated that treatment of hpg mice with testosterone propionate in the immediate neonatal period is necessary to allow full reproductive behaviors to be expressed following suitable endocrine stimulation at adult ages. 相似文献13.
Federico Mazzei Laura Ghigliotti Guillaume Lecointre Catherine Ozouf-Costaz Jean-Pierre Coutanceau William Detrich III Eva Pisano 《Polar Biology》2006,29(12):1071-1076
Using comparative cytogenetic techniques, we characterized the chromosomes of fishes from the family Bovichtidae, the basal lineage of the largely Antarctic suborder Notothenioidei. We focused on three Sub-Antarctic species of the genus Bovichtus that differ greatly in their circumpolar distributions: B. diacanthus (Tristan da Cunha Island Group), B. variegatus (New Zealand) and B. angustifrons (Tasmania). Chromosomes were analyzed both by conventional karyotyping and by cytogenetic mapping of ribosomal genes using fluorescence in situ hybridization. The three species displayed a strongly conserved karyotype consisting entirely of telocentric chromosomes (diploid number = 48; Fundamental Number = 48), in agreement with our previously published hypothesis that the bovichtid karyotype is the basal state for notothenioid fishes. The chromosomal distribution of ribosomal genes differed from those of most notothenioid species studied to date, with the 45S and 5S genes separated on two different chromosome pairs. Separation of two classes of ribosomal genes is the most widespread condition in teleosts, including the bovichtids. Most notothenioid lineages on the other hand exhibit a derived consolidation of these genes. 相似文献
14.
We compare the chromosomal 28S and 5S rDNA patterns of the spined loach C. taenia (2n = 48) from an exclusively diploid population and from a diploid–polyploid population using 28S and 5S rDNA probe preparation
and labelling, and fluorescence in situ hybridization (FISH). The 5S rDNA was located in two to three chromosome pairs, and separated from the 28S loci for the males
and one female (F1) from the diploid population. Loaches from a diploid–polyploid population, and one female (F2) from the
diploid population were characterized by at least one chromosome pair with 5S and 28S overlapping signals. The fishes differed
mainly in their number of 28S rDNA loci, located on 3–6 chromosomes. All individuals from both populations were characterized
by one acrocentric chromosome bearing a 28S rDNA signal on the telomeres of its long arm. The number of major ribosomal DNA
in the karyotype of C. taenia by FISH was always higher than the number of Ag-NORs. Our data confirm the extensive polymorphism of NORs in both populations,
as already has been observed in closely related Cobitis species, and less polymorphic 5S rDNA pattern. However, this preliminary result highlights the need for a wider scale study. 相似文献
15.
Hong H Coutanceau E Leclerc M Caleechurn L Leadlay PF Demangel C 《PLoS neglected tropical diseases》2008,2(10):e325
Background
Buruli ulcer (BU) is a progressive disease of subcutaneous tissues caused by Mycobacterium ulcerans. The pathology of BU lesions is associated with the local production of a diffusible substance, mycolactone, with cytocidal and immunosuppressive properties. The defective inflammatory responses in BU lesions reflect these biological properties of the toxin. However, whether mycolactone diffuses from infected tissues and suppresses IFN-γ responses in BU patients remains unclear.Methodology/Principal Findings
Here we have investigated the pharmacodistribution of mycolactone following injection in animal models by tracing a radiolabeled form of the toxin, and by directly quantifying mycolactone in lipid extracts from internal organs and cell subpopulations. We show that subcutaneously delivered mycolactone diffused into mouse peripheral blood and accumulated in internal organs with a particular tropism for the spleen. When mice were infected subcutaneously with M. ulcerans, this led to a comparable pattern of distribution of mycolactone. No evidence that mycolactone circulated in blood serum during infection could be demonstrated. However, structurally intact toxin was identified in the mononuclear cells of blood, lymph nodes and spleen several weeks before ulcerative lesions appear. Importantly, diffusion of mycolactone into the blood of M. ulcerans–infected mice coincided with alterations in the functions of circulating lymphocytes.Conclusion
In addition to providing the first evidence that mycolactone diffuses beyond the site of M. ulcerans infection, our results support the hypothesis that the toxin exerts immunosuppressive effects at the systemic level. Furthermore, they suggest that assays based on mycolactone detection in circulating blood cells may be considered for diagnostic tests of early disease. 相似文献16.
17.
Amiloride does not alter NaCl avoidance in Fischer-344 rats 总被引:2,自引:2,他引:0
Fischer-344 (F-344) rats differ from other common rat strains in that they
fail to show any preference for NaCl at any concentration in two- bottle
preference tests. Because 100 microM amiloride partially blocks the
NaCl-evoked chorda tympani (CT) response in electrophysiological studies,
we tested NaCl preference (0.068-0.273 M) in F-344 rats with and without
100 microM amiloride solution as the solvent. A third group was tested with
unadulterated NaCl solutions following CT transection. Amiloride had no
significant effect on the NaCl preference-aversion function, whereas CT
transection significantly reduced NaCl avoidance. These results suggest
that the amiloride-sensitive component of the NaCl response is not
necessary for F-344 rats to display avoidance of NaCl, but the entire CT
input is.
相似文献
18.
Cassava is infected by numerous geminiviruses in Africa and India that cause devastating losses to poor farmers. We here describe the molecular diversity of seven representative cassava mosaic geminiviruses (CMGs) infecting cassava from multiple locations in Tanzania. We report for the first time the presence of two isolates in East Africa: (EACMCV-[TZ1] and EACMCV-[TZ7]) of the species East African cassava mosaic Cameroon virus, originally described in West Africa. The complete nucleotide sequence of EACMCV-[TZ1] DNA-A and DNA-B components shared a high overall sequence identity to EACMCV-[CM] components (92% and 84%). The EACMCV-[TZ1] and -[TZ7] genomic components have recombinations in the same genome regions reported in EACMCV-[CM], but they also have additional recombinations in both components. Evidence from sequence analysis suggests that the two strains have the same ancient origin and are not recent introductions. EACMCV-[TZ1] occurred widely in the southern part of the country. Four other CMG isolates were identified: two were close to the EACMV-Kenya strain (named EACMV-[KE/TZT] and EACMV-[KE/TZM] with 96% sequence identity); one isolate, TZ10, had 98% homology to EACMV-UG2Svr and was named EACMV-UG2 [TZ10]; and finally one isolate was 95% identical to EACMV-[TZ] and named EACMV-[TZ/YV]. One isolate of African cassava mosaic virus with 97% sequence identity with other isolates of ACMV was named ACMV-[TZ]. It represents the first ACMV isolate from Tanzania to be sequenced. The molecular variability of CMGs was also evaluated using partial B component nucleotide sequences of 13 EACMV isolates from Tanzania. Using the sequences of all CMGs currently available, we have shown the presence of a number of putative recombination fragments that are more prominent in all components of EACMV than in ACMV. This new knowledge about the molecular CMG diversity in East Africa, and in Tanzania in particular, has led us to hypothesize about the probable importance of this part of Africa as a source of diversity and evolutionary change both during the early stages of the relationship between CMGs and cassava and in more recent times. The existence of multiple CMG isolates with high DNA genome diversity in Tanzania and the molecular forces behind this diversity pose a threat to cassava production throughout the African continent. 相似文献
19.
Celine Scornavacca Vincent Berry Vincent Lefort Emmanuel JP Douzery Vincent Ranwez 《BMC bioinformatics》2008,9(1):413
Background
Supertree methods combine phylogenies with overlapping sets of taxa into a larger one. Topological conflicts frequently arise among source trees for methodological or biological reasons, such as long branch attraction, lateral gene transfers, gene duplication/loss or deep gene coalescence. When topological conflicts occur among source trees, liberal methods infer supertrees containing the most frequent alternative, while veto methods infer supertrees not contradicting any source tree, i.e. discard all conflicting resolutions. When the source trees host a significant number of topological conflicts or have a small taxon overlap, supertree methods of both kinds can propose poorly resolved, hence uninformative, supertrees. 相似文献20.
Helen Baines Margaret O Nwagwu Graham R Hastie Roman A Wiles Terry M Mayhew Francis JP Ebling 《Reproductive biology and endocrinology : RB&E》2008,6(1):4