We report on new measurements of inclusive J/ψ polarization at mid-rapidity in p+p collisions at $\sqrt{s}$ = 200 GeV by the STAR experiment at RHIC. The polarization parameters, λθ, λφ, and λθφ, are ...measured as a function of transverse momentum (pT) in both the Helicity and CollinsSoper (CS) reference frames within pT < 10 GeV/c. Except for λθ in the CS frame at the highest measured pT, all three polarization parameters are consistent with 0 in both reference frames without any strong pT dependence. Several model calculations are compared with data, and the one using the Color Glass Condensate effective field theory coupled with non-relativistic QCD gives the best overall description of the experimental results, even though other models cannot be ruled out due to experimental uncertainties.
We have isolated and characterized a set of overlapping cDNA clones that encode the human centromere autoantigen centromere protein C (CENP-C). The identity of these clones has been established using ...several criteria. First, they were shown to encode a polypeptide that migrates at the expected position for CENP-C on SDS-polyacrylamide gel electrophoresis. Second, we have demonstrated that this polypeptide shares at least two epitopes with human CENP-C. Polyclonal antibodies were raised to fusion proteins encoded by nonoverlapping regions of the cDNA clones. These antibodies were shown to recognize a protein at a position appropriate for CENP-C on immunoblots of human chromosomal proteins. In addition, we used indirect immunofluorescence to demonstrate that these antibodies recognize centromeres of HeLa chromosomes in the expected pattern for CENP-C. Localization of CENP-C by immunoelectron microscopy reveals that this protein is a component of the inner kinetochore plate.
The human autoantigen CENP-C has been demonstrated by immunoelectron microscopy to be a component of the inner kinetochore plate. Here we have used antibodies raised against various portions of ...CENP-C to probe its function in mitosis. We show that nuclear microinjection of anti-CENP-C antibodies during interphase causes a transient arrest at the following metaphase. Injection of the same antibodies after the initiation of prophase, however, does not disrupt mitosis. Correspondingly, indirect immunofluorescence using affinity-purified human anti-CENP-C antibodies reveals that levels of CENP-C staining are reduced at centromeres in cells that were injected during interphase, but appear unaffected in cells which were injected during mitosis. Thus, we suggest that the injected antibodies cause metaphase arrest by reducing the amount of CENP-C at centromeres. Examination of kinetochores in metaphase-arrested cells by electron microscopy reveals that the number of trilaminar structures is reduced. More surprisingly, the few remaining kinetochores in these cells retain a normal trilaminar morphology but are significantly reduced in diameter. In cells arrested for extended periods, these small kinetochores become disrupted and apparently no longer bind microtubules. These observations are consistent with an involvement of CENP-C in kinetochore assembly, and suggest that CENP-C plays a critical role in both establishing and/or maintaining proper kinetochore size and stabilizing microtubule attachments. These findings also support the idea that proper assembly of kinetochores may be monitored by the cell cycle checkpoint preceding the transition to anaphase.
In many organisms, homolog pairing and synapsis at meiotic prophase depend on interactions between chromosomes and the nuclear membrane. Male Drosophila lack synapsis, but nonetheless, their ...chromosomes closely associate with the nuclear periphery at prophase I. To explore the functional significance of this association, we characterize mutations in nuclear blebber (nbl), a gene required for both spermatocyte nuclear shape and meiotic chromosome transmission. We demonstrate that nbl corresponds to dtopors, the Drosophila homolog of the mammalian dual ubiquitin/small ubiquitin-related modifier (SUMO) ligase Topors. We show that mutations in dtopors cause abnormalities in lamin localizations, centriole separation, and prophase I chromatin condensation and also cause anaphase I bridges that likely result from unresolved homolog connections. Bridge formation does not require mod(mdg4) in meiosis, suggesting that bridges do not result from misregulation of the male homolog conjunction complex. At the ultrastructural level, we observe disruption of nuclear shape, an uneven perinuclear space, and excess membranous structures. We show that dTopors localizes to the nuclear lamina at prophase, and also transiently to intranuclear foci. As a role of dtopors at gypsy insulator has been reported, we also asked whether these new alleles affected expression of the gypsy-induced mutation ct(6) and found that it was unaltered in dtopors homozygotes. Our results indicate that dTopors is required for germline nuclear structure and meiotic chromosome segregation, but in contrast, is not necessary for gypsy insulator function. We suggest that dtopors plays a structural role in spermatocyte lamina that is critical for multiple aspects of meiotic chromosome transmission.
The partially conserved Mad3/BubR1 protein is required during mitosis for the spindle assembly checkpoint (SAC). In meiosis, depletion causes an accelerated transit through prophase I and ...missegregation of achiasmate chromosomes in yeast, whereas in mice, reduced dosage leads to severe chromosome missegregation. These observations indicate a meiotic requirement for BubR1, but its mechanism of action remains unknown. We identified a viable bubR1 allele in Drosophila resulting from a point mutation in the kinase domain that retains mitotic SAC activity. In males, we demonstrate a dose-sensitive requirement for BubR1 in maintaining sister-chromatid cohesion at anaphase I, whereas the mutant BubFM protein localizes correctly. In bubR1 mutant females, we find that both achiasmate and chiasmate chromosomes nondisjoin mostly equationally consistent with a defect in sister-chromatid cohesion at late anaphase I or meiosis II. Moreover, mutations in bubR1 cause a consistent increase in pericentric heterochromatin exchange frequency, and although the synaptonemal complex is set up properly during transit through the germarium, It is disassembled prematurely in pro-phase by stage 1. Our results demonstrate that BubFR1 is essential to maintain sister-chromatid cohesion during meiotic progression in both sexes and for normal maintenance of SC in females.
Recent studies have begun to yield some insight into the structural and regulatory components of centromeres, and new assays have been developed that promise to be of use in advancing our ...understanding of centromere structure and function. In the budding yeast Saccharomyces cerevisiae new proteins that are required for centromere function have been identified and an in vitro microtubule-binding assay that should assist in dissecting the process of centromere microtubule attachment has been developed. The centromere-specific DNA sequences in the fission yeast Schizosaccharomyces pombe have been identified and partially characterized. In addition, several mammalian centromere proteins have been further characterized, and localization and inhibition studies suggest roles for these proteins in the regulation and assembly of a functional kinetochore.
Hyperalimentation worksheet Skaredoff, M N; Westerman, C; Hoffman, D ...
Critical care medicine
14, Številka:
1
Journal Article
Recenzirano
Parenteral hyperalimentation is an important means of nutritional support for critically ill patients. Calculating the amount of additives necessary for the appropriate compounding of ...hyperalimentations is a tedious process with many opportunities for error. A new computer program written in Pascal has been created to reduce pharmacy processing time. Menus and single-keystroke entry are implemented wherever practicable. A hard-copy printout and an individualized label are generated on command. Program testing has resulted in an 88% reduction of processing time.
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