''嘎拉''苹果对不同浓度1-MCP处理的反应

以'嘎拉'('Kid's Orange'×'Delicious')苹果为试材,研究了0℃贮藏期间及贮藏30、60、90和120 d后转入室温7d货架期间1-MCP(1-甲基环丙烯)对果实呼吸速率、乙烯释放速率、品质和蛋白质变化的影响.结果表明,1-MCP处理显著抑制嘎拉苹果贮藏期间和贮后货架期间呼吸和乙烯释放速率,延缓果实硬度、可滴定酸含量的下降,对可溶性固形物含量无影响.对照果实在贮藏过程中,出现5条明显的特异性蛋白条带,1-MCP处理能抑制特异蛋白表达.300 nL·L-1浓度1-MCP处理与600 nL·L-11-MCP处理作用效果无显著差异.     

Variability of serum levels of tumor necrosis factor-alpha, interleukin 6, and soluble interleukin 6 receptor over 2 years in young women

Serum levels of tumor necrosis factor-alpha (TNF-alpha), interleukin 6 (IL-6), and soluble interleukin 6 receptor (sIL-6R) have been studied as risk factors of cardiovascular disease in longitudinal studies. However, it is unknown about their long-term intra-individual variations and whether single measurements of these cytokines and receptor are reliable biomarkers in epidemiological studies. In this study, serum levels of TNF-alpha, IL-6, and sIL-6R were assayed by ELISAs in 36 young, healthy women from whom three blood samples were collected at 12-month intervals over 2 years, and the intraclass correlation coefficients (ICC) were estimated. The ICC of 0.73 (95% CI=0.49-0.79) for TNF-alpha was comparable to those of other commonly used biomarkers, justifying its use in epidemiological studies. The ICC of 0.48 (95% CI=0.25-0.58) for IL-6 was not optimal. However, IL-6 has been demonstrated as a consistent risk factor for cardiovascular disease, suggesting it could still be a useful biomarker if its disease association is substantial. The ICC of 0.36 (95% CI=0.10-0.47) for sIL-6R was relatively low, and multiple samples would need to be collected in prospective studies for this receptor.     

APC and EB1 function together in mitosis to regulate spindle dynamics and chromosome alignment

Recently, we have shown that a cancer causing truncation in adenomatous polyposis coli (APC) (APC(1-1450)) dominantly interferes with mitotic spindle function, suggesting APC regulates microtubule dynamics during mitosis. Here, we examine the possibility that APC mutants interfere with the function of EB1, a plus-end microtubule-binding protein that interacts with APC and is required for normal microtubule dynamics. We show that siRNA-mediated inhibition of APC, EB1, or APC and EB1 together give rise to similar defects in mitotic spindles and chromosome alignment without arresting cells in mitosis; in contrast inhibition of CLIP170 or LIS1 cause distinct spindle defects and mitotic arrest. We show that APC(1-1450) acts as a dominant negative by forming a hetero-oligomer with the full-length APC and preventing it from interacting with EB1, which is consistent with a functional relationship between APC and EB1. Live-imaging of mitotic cells expressing EB1-GFP demonstrates that APC(1-1450) compromises the dynamics of EB1-comets, increasing the frequency of EB1-GFP pausing. Together these data provide novel insight into how APC may regulate mitotic spindle function and how errors in chromosome segregation are tolerated in tumor cells.     

Exopolysaccharide biosynthesis genes required for social motility in Myxococcus xanthus

Social (S)-motility in Myxococcus xanthus is a flagellum-independent gliding motility system that allows bacteria to move in groups on solid surfaces. S-motility has been shown to require type IV pili (TFP), exopolysaccharide (EPS; a component of fibrils) and lipopolysaccharide (LPS). Previously, information concerning EPS biogenesis in M. xanthus was lacking. In this study, we screened 5000 randomly mutagenized colonies for defects in S-motility and EPS and identified two genetic regions essential for EPS biogenesis: the EPS synthesis (eps) region and the EPS-associated (eas) region. Mutants with insertions in the eps and eas regions were defective in S-motility and fruiting body formation. These mutants failed to bind the dye calcofluor white, indicating that they lacked EPS; however, they retained normal TFP and LPS. Analysis of the eps locus showed several open reading frames (ORFs) that encode homologues to glycosyltransferases, glucanases and EPS transporters as well as regulatory proteins; the eas locus contains two ORFs: one exhibits homology to hypothetical proteins with a conserved domain of unknown function and the other displays no apparent homology to other proteins in the database. Further genetic mutagenesis analysis indicates that the whole eps region is involved in the biosynthesis of fibrils and fibril EPS. The operon at the proximal end of the eps region was analysed by generating in-frame deletion mutations. These mutants showed varying degrees of defects in the bacterium's ability to produce EPS or perform EPS-related functions, confirming the involvement of these genes in M. xanthus EPS biogenesis.     

Synthesis and SAR of diazepine and thiazepine TACE and MMP inhibitors

Potent and selective TACE and MMP inhibitors utilizing the diazepine and thiazepine ring systems were synthesized and evaluated for biological activity in in vitro and in vivo models of TNF-alpha release. Oral activity in the mouse LPS model of TNF-alpha release was seen. Efficacy in the mouse collagen induced arthritis model was achieved with diazepine 20.     

Ecological implications of the emergence of non-toxic subcultures from toxic Microcystis strains

Two toxic, microcystin-producing, Microcystis sp. strains KLL MG-K and KLL MB-K were isolated as single colonies on agar plates from Lake Kinneret, Israel. Two non-toxic subcultures, MG-J and MB-J spontaneously succeeded the toxic ones under laboratory conditions. Southern analyses showed that MG-J and MB-J are lacking at least 34 kb of the mcy region, encoding the microcystin synthetase. Analyses of the 16S rRNA genes, the intergenic spacer region between cpcB and cpcA and the patterns of the polymerase chain reaction products of randomly amplified polymorphic DNA and highly iterated palindrome, and presence of mobile DNA elements did not allow unequivocal distinction between toxic and non-toxic subcultures. Laboratory and field experiments indicated an advantage of the toxic strain over its non-toxic successor. When grown separated by a membrane, which allowed passage of the media but not the cells, MG-K severely inhibited the growth of MG-J. Furthermore, when MG strains were placed in dialysis bags in Lake Kinneret during the season in which Microcystis is often observed, cells of MG-J lysed, whereas MG-K survived. Mechanisms whereby the non-toxic subcultures emerged and prevailed over the corresponding toxic ones under laboratory conditions, as well as a possible role of microcystin under natural conditions, are discussed.     

Validation of a brief telephone battery for neurocognitive assessment of patients with pulmonary arterial hypertension

Background

The effects of pulmonary arterial hypertension on brain function are not understood, despite patients'' frequent complaints of cognitive difficulties. Using clinical instruments normally administered during standard in-person assessment of neurocognitive function in adults, we assembled a battery of tests designed for administration over the telephone. The purpose was to improve patient participation, facilitate repeated test administration, and reduce the cost of research on the neuropsychological consequences of acute and chronic cardiorespiratory diseases. We undertook this study to validate telephone administration of the tests.

Methods

23 adults with pulmonary arterial hypertension underwent neurocognitive assessment using both standard in-person and telephone test administration, and the results of the two methods compared using interclass correlations.

Results

For most of the tests in the battery, scores from the telephone assessment correlated strongly with those obtained by in-person administration of the same tests. Interclass correlations between 0.5 and 0.8 were observed for tests that assessed attention, memory, concentration/working memory, reasoning, and language/crystallized intelligence (p ≤ 0.05 for each). Interclass correlations for the Hayling Sentence Completion test of executive function approached significance (p = 0.09). All telephone tests were completed within one hour.

Conclusion

Administration of this neurocognitive test battery by telephone should facilitate assessment of neuropsychological deficits among patients with pulmonary arterial hypertension living across broad geographical areas, and may be useful for monitoring changes in neurocognitive function in response to PAH-specific therapy or disease progression.     

Theoretical study of the electron affinities of the alkaline-earth tetramers possessing T d symmetry: Be4 and Mg4

The electron affinities of beryllium and magnesium tetramers are calculated at the ROMP2 level employing the Dunning-type aug-cc-pVQZ basis set. The vertical electron detachment energy (VEDE) amounts to 1.685 eV for Be₄^– and 0.943 eV for Mg₄ . The decomposition of the VEDE into physical components and an atomic orbital population analysis are used to elucidate the nature of the outer electron binding in these anions.Figure The lowest unoccupied molecular orbitals in the ground state of Mg4 : a LUMO, symmetry A₁, b LUMO + 1, symmetry T₂; c the highest occupied molecular orbital (HOMO), symmetry A1 in the ground state of Mg₄^–.