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21.
Quashie NB Dorin-Semblat D Bray PG Biagini GA Doerig C Ranford-Cartwright LC De Koning HP 《The Biochemical journal》2008,411(2):287-295
Plasmodium falciparum is incapable of de novo purine biosynthesis, and is absolutely dependent on transporters to salvage purines from the environment. Only one low-affinity adenosine transporter has been characterized to date. In the present study we report a comprehensive study of purine nucleobase and nucleoside transport by intraerythrocytic P. falciparum parasites. Isolated trophozoites expressed (i) a high-affinity hypoxanthine transporter with a secondary capacity for purine nucleosides, (ii) a separate high-affinity transporter for adenine, (iii) a low-affinity adenosine transporter, and (iv) a low-affinity/high-capacity adenine carrier. Hypoxanthine was taken up with 12-fold higher efficiency than adenosine. Using a parasite clone with a disrupted PfNT1 (P. falciparum nucleoside transporter 1) gene we found that the high-affinity hypoxanthine/nucleoside transport activity was completely abolished, whereas the low-affinity adenosine transport activity was unchanged. Adenine transport was increased, presumably to partly compensate for the loss of the high-affinity hypoxanthine transporter. We thus propose a model for purine salvage in P. falciparum, based on the highly efficient uptake of hypoxanthine by PfNT1 and a high capacity for purine nucleoside uptake by a lower affinity carrier. 相似文献
22.
Two novel gene orders and the role of light-strand replication in rearrangement of the vertebrate mitochondrial genome 总被引:22,自引:8,他引:14
Macey JR; Larson A; Ananjeva NB; Fang Z; Papenfuss TJ 《Molecular biology and evolution》1997,14(1):91-104
Two novel mitochondrial gene arrangements are identified in an agamid
lizard and a ranid frog. Statistical tests incorporating phylogeny indicate
a link between novel vertebrate mitochondrial gene orders and movement of
the origin of light-strand replication. A mechanism involving errors in
light-strand replication and tandem duplication of genes is proposed for
rearrangement of vertebrate mitochondrial genes. A second mechanism
involving small direct repeats also is identified. These mechanisms
implicate gene order as a reliable phylogenetic character. Shifts in gene
order define major lineages without evidence of parallelism or reversal.
The loss of the origin of light-strand replication from its typical
vertebrate position evolves in parallel and, therefore, is a less reliable
phylogenetic character. Gene junctions also evolve in parallel. Sequencing
across multigenic regions, in particular transfer RNA genes, should be a
major focus of future systematic studies to locate novel gene orders and to
provide a better understanding of the evolution of the vertebrate
mitochondrial genome.
相似文献
23.
In cell suspension of Desulfovibrio desulfuricans B-1388, oxidation of CO as the only energy source is associated with reduction of SO42-. After a 2-h incubation of cells in 8% CO, 81% of the gas is converted. Oxidation of 1 mole CO results in formation of 0.23 mole H2S. Intracellular ATP content increases from 2.5 (control) to 8.3 nmoles/mg (during CO conversion). Dinitrophenol inhibits sulfate reduction and CO oxidation. CO dehydrogenase was detected in cytoplasmic and membrane cell fractions (59 and 34%, respectively). 相似文献
24.
25.
Chattopadhyay MB Mukherjee S Kulkarni I Vijayan V Doloi M Kanjilal N Chatterjee M 《Cancer cell international》2005,5(1):16
Combined effect of vanadium and beta-carotene on rat liver DNA-chain break and Proton induced X-ray emission (PIXE) analysis
was studied during a necrogenic dose (200 mg/kg of body weight) of Diethyl Nitrosamine (DENA) induced rat liver carcinogenesis.
Morphological and histopathological changes were observed as an end point biomarker. Supplementation of vanadium (0.5 ppm
ad libitum) in drinking water and beta-carotene in the basal diet (120 mg/Kg of body weight) were performed four weeks before DENA treatment
and continued till the end of the experiment (16 weeks). PIXE analysis revealed the restoration of near normal value of zinc,
copper, and iron, which were substantially altered when compared to carcinogen treated groups. Supplementation of both vanadium
and beta-carotene four weeks before DENA injection was found to offer significant (64.73%, P < 0.001) protection against generation
of single-strand breaks when compared with the carcinogen control counter parts. A significant stabilization of hepatic architecture
of the cells was observed as compared to carcinogen control in vanadium plus beta-carotene treated group. This study thus
suggests that vanadium, a prooxidant but potential therapeutic agent yield safe and effective pharmacological formulation
with beta-carotene, an antioxidant, in the inhibition of experimental rat hepatocarcinogenesis. 相似文献
26.
Quashie PK Mesplède T Han YS Oliveira M Singhroy DN Fujiwara T Underwood MR Wainberg MA 《Journal of virology》2012,86(5):2696-2705
27.
Hunter NB Moseley 《BMC bioinformatics》2010,11(1):139