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Plant microtubules are organized into specific cell cycle-dependent arrays that have been implicated in diverse cellular processes, including cell division and organized cell expansion. Mutations in four Arabidopsis genes collectively called the PILZ group result in lethal embryos that consist of one or a few grossly enlarged cells. The mutant embryos lack microtubules but not actin filaments. Whereas the cytokinesis-specific syntaxin KNOLLE is not localized properly, trafficking of the putative auxin efflux carrier PIN1 to the plasma membrane is normal. The four PILZ group genes were isolated by map-based cloning and are shown to encode orthologs of mammalian tubulin-folding cofactors (TFCs) C, D, and E, and associated small G-protein Arl2 that mediate the formation of alpha/beta-tubulin heterodimers in vitro. The TFC C ortholog, PORCINO, was detected in cytosolic protein complexes and did not colocalize with microtubules. Another gene with a related, although weaker, embryo-lethal phenotype, KIESEL, was shown to encode a TFC A ortholog. Our genetic ablation of microtubules shows their requirement in cell division and vesicle trafficking during cytokinesis, whereas cell growth is mediated by microtubule-independent vesicle trafficking to the plasma membrane during interphase.  相似文献   
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High circulating concentration of insulin-like growth factor-I (IGF-I) and low circulating concentration of IGF binding protein-3 (IGFBP-3) have been associated with increased risk for breast, prostate, and colorectal cancers. Building on previous work in the Multiethnic Cohort (MEC) showing significant differences in IGF-I levels across racial/ethnic groups, we investigated which lifestyle and dietary factors are associated with levels of IGF-I and IGFBP-3 in a random sample of 1,000 MEC participants, which included Native Hawaiian, African American, Japanese, Latino, and White men and women. Crude analyses confirmed the existence of differences in protein levels with race/ethnicity, sex, age, and body size. Reproductive, physical activity, smoking, and diet variables had less consistent effects. In multivariate analyses, IGF-I levels were lower and IGFBP-3 were higher in females versus males. IGF-I and IGFBP-3 declined with increasing age in both genders. Women in the highest quartile of body mass index showed depressed IGF-I and IGFBP-3 levels; in men, height was significantly positively associated with both proteins. In women, alcohol was directly associated with IGFBP-3. Both proteins were lowest among female Latinos. IGF-I was highest among female African Americans. In men, IGFBP-3 was lowest among African Americans. Overall, although these factors were statistically significant determinants of IGF-related protein levels, they did not explain much of the variation in these levels. A positive correlation was found between IGF-I levels (ng/mL) and colon cancer incidence rates (per 100,000) within the MEC by race/ethnicity for both sexes but not for either breast or prostate cancer.  相似文献   
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The Coulter LH 750 is a new haematology analyser with several new features: a count of nucleated red blood cells (NRBCs), automated WBC correction in presence of a flag indicating a cellular interference and a lower incidence of platelet or WBC interference flags when compared with the GEN.S, our current instrument. We had three main goals in our study: evaluating the LH 750 WBC counts when a GEN.S flag suggests a risk of WBC interference, ascertaining whether the platelet counts not flagged by the LH 750 were accurately assessed in samples flagged by the GEN.S and evaluating the NRBC assay provided by the LH 750. Flow cytometry, using CD45 and CD41, respectively for WBC and platelet labelling, was used as a reference method to assess the accuracy of the LH 750 counts. NRBC were identified by double labelling with propidium iodide (PI) and CD45, NRBCs being CD45-/PI+. A significant relationship was found between LH 750 and flow cytometric WBC counts, whether a WBC correction was made by the LH 750 (r = 0.9809, n = 54) or not (r = 0.9901, n = 23). A highly significant relationship was observed for platelets not only in the range from 0 to 450 x 10(9)/l (r = 0.981, n = 108) but also in cases of thrombocytopenia (range: 0-80 x 10(9)/l; r = 0.956, n = 51). In samples with NRBCs, the NRBC percentages given by the LH 750 and by flow cytometry were highly correlated (r = 0.977, n = 60) and WBC counts were accurate. In conclusion, the reduction in flagging by the LH 750, the accuracy of the results, and the availability of a NRBC count, constitute major advantages.  相似文献   
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