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Melting and reannealing of purified kinetoplast DNA (kDNA) from Crithidia fasciculata, Trypanosoma mega, and T. brucei have been studied with an automated optical system. The slow reassociation rate of trypanosome kDNA is due neither to the formation of hyperpolymers nor to mispairing of bases and certainly reflects extensive sequence heterogeneity. Simulation of the reassociation kinetics indicates that the kDNA comprises essentially two kinetic components: a fast renaturing component which might be a common sequence present in all the minicircles and a slow renaturing component which is responsible for minicircle heterogeneity. The rapidly renaturing component is more abundant in Crithidia than in trypanosomes. 相似文献
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Nurtaza Aidana Magzumova Gulmira Yessimseitova Assel Karimova Venera Shevtsov Alexandr Silayev Dmitriy Lutsay Viktoriya Ramankulov Yerlan Kakimzhanova Almagul 《In vitro cellular & developmental biology. Plant》2021,57(6):965-976
In Vitro Cellular & Developmental Biology - Plant - Biodiversity conservation requires advanced and effective ex situ plant propagation techniques. The present study was conducted to optimize... 相似文献
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A gene from the variant surface glycoprotein expression site encodes one of several transmembrane adenylate cyclases located on the flagellum of Trypanosoma brucei. 总被引:9,自引:1,他引:8 下载免费PDF全文
P Paindavoine S Rolin S Van Assel M Geuskens J C Jauniaux C Dinsart G Huet E Pays 《Molecular and cellular biology》1992,12(3):1218-1225
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Nabila El-Bassel Louisa Gilbert Stacey A. Shaw Gaukhar Mergenova Assel Terlikbayeva Sholpan Primbetova Xin Ma Mingway Chang Leyla Ismayilova Tim Hunt Brooke West Elwin Wu Chris Beyrer 《PloS one》2016,11(3)
Objectives
We examined whether mobility, migrant status, and risk environments are associated with sexually transmitted infections (STIs) and HIV risk behaviors (e.g. sex trading, multiple partners, and unprotected sex).Methods
We used Respondent Driven Sampling (RDS) to recruit external male migrant market vendors from Kyrgyzstan, Uzbekistan, and Tajikistan as well internal migrant and non-migrant market vendors from Kazakhstan. We conducted multivariate logistic regressions to examine the effects of mobility combined with the interaction between mobility and migration status on STIs and sexual risk behaviors, when controlling for risk environment characteristics.Results
Mobility was associated with increased risk for biologically-confirmed STIs, sex trading, and unprotected sex among non-migrants, but not among internal or external migrants. Condom use rates were low among all three groups, particularly external migrants. Risk environment factors of low-income status, debt, homelessness, and limited access to medical care were associated with unprotected sex among external migrants.Conclusion
Study findings underscore the role mobility and risk environments play in shaping HIV/STI risks. They highlight the need to consider mobility in the context of migration status and other risk environment factors in developing effective prevention strategies for this population. 相似文献6.
miRNAs regulate gene expression by binding with mRNAs of many genes. Studying their effects on genes involved in oncogenesis is important in cancer diagnostics and therapeutics. The RNAHybrid 2.1 program was used to predict the strong miRNA binding sites (p < 0.0005) in target mRNAs. The program Finder 2.2 was created to verify 784 intergenic miRNAs (ig-miRNA) origin. Among 54 considered oncogenes and tumor suppressor genes, 47 genes are the best targets for ig-miRNAs. Accordingly, these genes are strongly regulated by 111 ig-miRNAs. Some miRNAs bind several mRNAs, and some mRNAs have several binding sites for miRNAs. Of the 54 mRNAs, 21.8%, 43.0%, and 35.2% of the miRNA binding sites are present in the 5'UTRs, CDSes, and 3'UTRs, respectively. The average density of the binding sites for miRNAs in the 5'UTR was 4.4 times and 4.1 times greater than in the CDS and the 3'UTR, respectively. Three types of interactions between miRNAs and mRNAs were identified, which differ according to the region of the miRNA bound to the mRNA: 1) binding occurs predominantly via the 3'-region of the miRNA; 2) binding occurs predominantly through the central region of the miRNA; and 3) binding occurs predominantly via the 5'-region of the miRNA. Several miRNAs effectively regulate only one gene, and this information could be useful in molecular medicine to modulate translation of the target mRNA. We recommend described new sites for validation by experimental investigation. 相似文献
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A novel circular DNA, 11.3 μm in contour length, has been found in a pure kinetoplast DNA fraction of Crithidia luciliae. The mitochondrial nature of the kinetoplast and the absence of these large circular molecules in the nuclear fraction of DNA suggest that they constitute the mitochondrial genome of this species. 相似文献
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Telomere interactions may condition the programming of antigen expression in Trypanosoma brucei. 总被引:5,自引:0,他引:5 下载免费PDF全文
The AnTat 1.1 antigen type typically occurs late in a chronic infection by the EATRO 1125 stock of Trypanosoma brucei. The AnTat 1.1 gene, which is located 24 kb from a chromosome end, seems exclusively expressed by acting as a donor in gene conversion events targeted to the telomeric expression site. We report that this gene is sufficiently provided with the homology blocks required for recombination with the expression site, and is not interrupted by stop codons up to the 3' block of homology. A possible reason for its low probability of activation is an inverse orientation with respect to the proximal chromosome end, since, if correctly positioned, it is readily expressed at an early stage of infection, following gene conversion. This suggests that interactions between chromosome ends may precede and favour the rearrangements leading to antigenic variation. 相似文献
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Specific detection of kinetoplast DNA in cytological preparations of trypanosomes by hybridization with complementary RNA 总被引:3,自引:0,他引:3
M Steinert S Van Assel P Borst J N Mol C M Kleisen B A Newton 《Experimental cell research》1973,76(1):175-185
Fibroblasts from patients with Xeroderma pigmentosum (X.P.) were used together with normal fibroblasts, in order to test (1) whether complementation takes place in heterokaryons formed by these cells; (2) whether the ‘factor’ defective in X.P. limits the rate of DNA repair synthesis in normal fibroblasts. Proximity to normal fibroblasts as well as treatment with their extract does not significantly affect the DNA repair synthesis of the abnormal cells, as measured by autoradiography. By contrast, in heterodikaryons a corrective substance rapidly diffuses into the abnormal nuclei which then perform a normal amount of DNA repair synthesis. Such complementation does not require de novo protein synthesis, since it occurs in the presence of daunomycin or cycloheximide. Furthermore, the dilution of normal ‘factor’, which follows diffusion, does not prevent each nucleus in these hybrids from showing a normal amount of DNA repair synthesis even after UV doses capable of saturating the DNA repair system of the normal parental cells. Thus it seems that in normal fibroblasts the factor defective in X.P. is not rate limiting.Nevertheless, a comparison of heteropolykaryons with a high (3:1) and a low (1:1.25) average ratio of X.P. to normal nuclei shows that, in the former, DNA repair synthesis is reduced. This effect, which seems rather long lasting, indicates that the carrier state for X.P. could be detected using the dosimetric help of heteropolykaryons. 相似文献
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Dineke Frentz Charles A. B. Boucher Matthias Assel Andrea De Luca Massimiliano Fabbiani Francesca Incardona Pieter Libin Nino Manca Viktor Müller Breanndán ó. Nualláin Roger Paredes Mattia Prosperi Eugenia Quiros-Roldan Lidia Ruiz Peter M. A. Sloot Carlo Torti Anne-Mieke Vandamme Kristel Van Laethem Maurizio Zazzi David A. M. C. van de Vijver 《PloS one》2010,5(7)