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91.
Estimates of nuclear genome size for 9 Selaginella species were obtained using flow cytometry, and measurements for 7 of these species are reported for the first time. Estimates range from 0.086 to 0.112 pg per holoploid genome (84-110 Mb). The data presented here agree with the previously published flow cytometric results for S. moellendorffii. Within the 9 species sampled here, chromosome number varies from 2n = 16 to 2n = 27. Nuclear genome size appears to be strongly correlated with chromosome number (Spearman's rank correlation; p = 0.00003725). Cultivated S. moellendorffii lacks sexual reproduction--manifest by the production of abortive megasporangia. Flow cytometric data generated from a herbarium specimen of a fertile wild-collected S. moellendorffii are virtually indistinguishable from the data generated from fresh material (0.088 vs. 0.089 pg/1C). Therefore, the limited fertility observed in cultivated plants is probably not the result of abnormal chromosome number (e.g., induced by interspecific hybridization). 相似文献
92.
Sutton D Wang S Nasongkla N Gao J Dormidontova EE 《Experimental biology and medicine (Maywood, N.J.)》2007,232(8):1090-1099
Polymer micelles with two different core-forming blocks, poly(d,l -lactide) (PLA) and poly(epsilon-caprolactone) (PCL), but the same coronal material, poly(ethylene glycol) (PEG), were investigated in this study as nanoscopic drug carriers. The release of two different drugs, doxorubicin (DOX) and beta-lapachone (beta-lap), from PEG(5k)-b-PCL(5k) and PEG(5k)-b-PLA(5k) micelles was studied at pH 5.0 and 7.4. Mathematical solutions of both Higuchi's model and Fickian diffusion equations were utilized to elucidate the differences between the micelle core materials for the two drugs. The neutral and smaller of the two drugs tested, beta-lap, demonstrated faster, pH-independent release, suggesting that no substantial changes occurred in either micelle core at lower pH. In contrast, the release rate of DOX was found to noticeably increase at lower pH with a larger cumulative amount of drug released. Different core materials were shown to have considerable influence on the release kinetics of both drugs: in both cases, the more hydrophobic PCL core showed slower drug release rates compared with the less hydrophobic PLA core. 相似文献
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Background
The pathways regulating the transition of mammalian cells from quiescence to proliferation are mediated by multiple miRNAs. Despite significant improvements in our understanding of miRNA targeting, the majority of miRNA regulatory networks are still largely unknown and require experimental validation.Results
Here we identified miR-503, miR-103, and miR-494 as negative regulators of proliferation in primary human cells. We experimentally determined their genome wide target profiles using RNA-induced silencing complex (RISC) immunoprecipitations and gene expression profiling. Analysis of the genome wide target profiles revealed evidence of extensive regulation of gene expression through non-canonical target pairing by miR-503. We identified the proto-oncogene DDHD2 as a target of miR-503 that requires pairing outside of the canonical 5′ seed region of miR-503, representing a novel mode of miRNA-target pairing. Further bioinformatics analysis implicated miR-503 and DDHD2 in breast cancer tumorigenesis.Conclusions
Our results provide an extensive genome wide set of targets for miR-503, miR-103, and miR-494, and suggest that miR-503 may act as a tumor suppressor in breast cancer by its direct non-canonical targeting of DDHD2.Electronic supplementary material
The online version of this article (doi:10.1186/s12864-015-1279-9) contains supplementary material, which is available to authorized users. 相似文献98.
Huber D Rajagopalan N Preissler S Rocco MA Merz F Kramer G Bukau B 《Molecular cell》2011,41(3):343-353
In Escherichia coli, translocation of exported proteins across the cytoplasmic membrane is dependent on the motor protein SecA and typically begins only after synthesis of the substrate has already been completed (i.e., posttranslationally). Thus, it has generally been assumed that the translocation machinery also recognizes its protein substrates posttranslationally. Here we report a specific interaction between SecA and the ribosome at a site near the polypeptide exit channel. This interaction is mediated by conserved motifs in SecA and ribosomal protein L23, and partial disruption of this interaction in?vivo by introducing mutations into the genes encoding SecA or L23 affects the efficiency of translocation by the posttranslational pathway. Based on these findings, we propose that SecA could interact with its nascent substrates during translation in order to efficiently channel them into the "posttranslational" translocation pathway. 相似文献
99.
Carroll DS Emerson GL Li Y Sammons S Olson V Frace M Nakazawa Y Czerny CP Tryland M Kolodziejek J Nowotny N Olsen-Rasmussen M Khristova M Govil D Karem K Damon IK Meyer H 《PloS one》2011,6(8):e23086
Cowpox virus (CPXV) is described as the source of the first vaccine used to prevent the onset and spread of an infectious disease. It is one of the earliest described members of the genus Orthopoxvirus, which includes the viruses that cause smallpox and monkeypox in humans. Both the historic and current literature describe "cowpox" as a disease with a single etiologic agent. Genotypic data presented herein indicate that CPXV is not a single species, but a composite of several (up to 5) species that can infect cows, humans, and other animals. The practice of naming agents after the host in which the resultant disease manifests obfuscates the true taxonomic relationships of "cowpox" isolates. These data support the elevation of as many as four new species within the traditional "cowpox" group and suggest that both wild and modern vaccine strains of Vaccinia virus are most closely related to CPXV of continental Europe rather than the United Kingdom, the homeland of the vaccine. 相似文献
100.
Roess AA Monroe BP Kinzoni EA Gallagher S Ibata SR Badinga N Molouania TM Mabola FS Mombouli JV Carroll DS MacNeil A Benzekri NA Moses C Damon IK Reynolds MG 《PLoS neglected tropical diseases》2011,5(10):e1356