羊蹄甲属植物种子的裂解色谱鉴定法研究

本文探索了裂解气相色谱法作为植物种子分类表征方法的可能性。对豆科植物中不同属、不同亚属及相同亚属的共10种种子的裂解色谱图,用分区编码法进行区别,分析结果表明,不同种子最少有一个编码不同,方法简易快速,可为高等植物种子的区分提供一种佐证手段。     

Patterns of Risk of Cancer in Patients with Metal-on-Metal Hip Replacements versus Other Bearing Surface Types: A Record Linkage Study between a Prospective Joint Registry and General Practice Electronic Health Records in England

Background

There are concerns that metal-on-metal hip implants may cause cancer. The objective of this study was to evaluate patterns and timing of risk of cancer in patients with metal-on-metal total hip replacements (THR).

Methods

In a linkage study between the English National Joint Registry (NJR) and the Clinical Practice Research Datalink (CPRD), we selected all THR surgeries (NJR) between 2003 and 2010 (n = 11,540). THR patients were stratified by type of bearing surface. Patients were followed up for cancer and Poisson regression was used to derive adjusted relative rates (RR).

Results

The risk of cancer was similar in patients with hip resurfacing (RR 0.69; 95% Confidence Interval [CI] 0.39–1.22) or other types of bearing surfaces (RR 0.96; 95% CI 0.64–1.43) compared to individuals with stemmed metal-on-metal THR. The pattern of cancer risk over time did not support a detrimental effect of metal hip implants. There was substantial confounding: patients with metal-on-metal THRs used fewer drugs and had less comorbidity.

Conclusions

Metal-on-metal THRs were not associated with an increased risk of cancer. There were substantial baseline differences between the different hip implants, indicating possibility of confounding in the comparisons between different types of THR implants.     

Activation of the Endoplasmic Reticulum Calcium Sensor STIM1 and Store-Operated Calcium Entry by Rotavirus Requires NSP4 Viroporin Activity

Rotavirus nonstructural protein 4 (NSP4) induces dramatic changes in cellular calcium homeostasis. These include increased endoplasmic reticulum (ER) permeability, resulting in decreased ER calcium stores and activation of plasma membrane (PM) calcium influx channels, ultimately causing a 2- to 4-fold elevation in cytoplasmic calcium. Elevated cytoplasmic calcium is absolutely required for virus replication, but the underlying mechanisms responsible for calcium influx remain poorly understood. NSP4 is an ER-localized viroporin, whose activity depletes ER calcium, which ultimately leads to calcium influx. We hypothesized that NSP4-mediated depletion of ER calcium activates store-operated calcium entry (SOCE) through activation of the ER calcium sensor stromal interaction molecule 1 (STIM1). We established and used a stable yellow fluorescent protein-expressing STIM1 cell line (YFP-STIM1) as a biosensor to assess STIM1 activation (puncta formation) by rotavirus infection and NSP4 expression. We found that STIM1 is constitutively active in rotavirus-infected cells and that STIM1 puncta colocalize with the PM-localized Orai1 SOCE calcium channel. Expression of wild-type NSP4 activated STIM1, resulting in PM calcium influx, but an NSP4 viroporin mutant failed to induce STIM1 activation and did not activate the PM calcium entry pathway. Finally, knockdown of STIM1 significantly reduced rotavirus yield, indicating STIM1 plays a critical role in virus replication. These data demonstrate that while rotavirus may ultimately activate multiple calcium channels in the PM, calcium influx is predicated on NSP4 viroporin-mediated activation of STIM1 in the ER. This is the first report of viroporin-mediated activation of SOCE, reinforcing NSP4 as a robust model to understand dysregulation of calcium homeostasis during virus infections.     

Effect of external stresses on protein conformation: a computer modelling study

The increasing use of digital technologies such as mobile phones has led to major health concerns about the effects of non-ionizing pulsed radiation exposure. We believe that the health implications of exposure to radiation cannot be fully understood without establishing the molecular mechanisms of biological effects of pulsed microwaves. We aim to establish methods for studying the molecular mechanisms of protein structural and energetic changes occurring due to external stresses related to non-ionizing radiation by using a combination of experimental and theoretical approaches. In this paper, we present the results from our fully atomistic simulation study of chemical and thermal stress response of a prototype protein, insulin. We performed a series of molecular dynamics simulations of insulin in solution under equilibrium conditions, under chemical stress (imitated by reducing the disulfide bonds in the protein molecule), and under short-lived thermal stress (imitated by increasing simulation temperature for up to 2 ns). The resultant protein conformational behaviour was analysed for various properties with the aim of establishing analysis routines for classification of protein unfolding pathways and associated molecular mechanisms.Submitted as a record of the 2002 Australian Biophysical Society meeting     

Robust smooth segmentation approach for array CGH data analysis

MOTIVATION: Array comparative genomic hybridization (aCGH) provides a genome-wide technique to screen for copy number alteration. The existing segmentation approaches for analyzing aCGH data are based on modeling data as a series of discrete segments with unknown boundaries and unknown heights. Although the biological process of copy number alteration is discrete, in reality a variety of biological and experimental factors can cause the signal to deviate from a stepwise function. To take this into account, we propose a smooth segmentation (smoothseg) approach. METHODS: To achieve a robust segmentation, we use a doubly heavy-tailed random-effect model. The first heavy-tailed structure on the errors deals with outliers in the observations, and the second deals with possible jumps in the underlying pattern associated with different segments. We develop a fast and reliable computational procedure based on the iterative weighted least-squares algorithm with band-limited matrix inversion. RESULTS: Using simulated and real data sets, we demonstrate how smoothseg can aid in identification of regions with genomic alteration and in classification of samples. For the real data sets, smoothseg leads to smaller false discovery rate and classification error rate than the circular binary segmentation (CBS) algorithm. In a realistic simulation setting, smoothseg is better than wavelet smoothing and CBS in identification of regions with genomic alterations and better than CBS in classification of samples. For comparative analyses, we demonstrate that segmenting the t-statistics performs better than segmenting the data. AVAILABILITY: The R package smoothseg to perform smooth segmentation is available from http://www.meb.ki.se/~yudpaw.     

Evolutionary duplication of lipo oligochitin-like receptor genes in soybean differentiates their function in cell division and cell invasion

Gene duplication in evolution has long been viewed as a mechanism for functional divergence. We recently cloned two related lipo-oligochitin receptor genes (GmNFR1α and GmNFR1β) in Glycine max (soybean) that allowed the distinction of two nodulation factor (NF) responses during early legume nodule ontogeny, namely invasion of the root hair and concomitant cortical cell divisions. Root-controlled GmNFR1α mutants nod49 and rj1 failed to form curled root hairs, infection threads and nodules but develop subepidermal cortical cell divisions (CCD) and mycorrhizal associations. In contrast GmNFR1β mutant PI437.654 had full symbiotic abilities. However, GmNFR1α mutants formed normal nodules at reduced frequency when inoculated with high Bradyrhizobium titers. The mutation was complemented in Agrobacterium rhizogenes K599 transformed roots using both CaMV 35S and the native GmNFR1α promoters. GmNFR1α may encode a high affinity NF receptor responsible for the entire nodulation cascade while GmNFR1β with lower affinity to NF suffices to induce cell divisions but not early infection events.Key words: gene duplication, LysM receptor kinase, Glycine max L. Merr., nodulation, cell division, cell invasionNodulation and symbiotic nitrogen fixation provide a major conduit for nitrogen into the earth''s biosphere, capable of replacing synthetic fertilizer augmentation of high input food production. With ever-increasing fossil fuel costs needed for fertilizer production, storage, distribution and application, the understanding and concomitant optimization of the natural symbiotic process of plant-bacterium interaction is gaining emphasis.     

Genotype-dependent expression of endothelial nitric oxide synthase (eNOS) and its regulatory proteins in cultured endothelial cells

DNA polymorphisms in endothelial nitric oxide synthase (eNOS) gene have been shown to be associated with constitutive eNOS expression and coronary artery disease (CAD). In the present study we explored the hypothesis whether genotype-dependent effects can be maintained in vitro during replication, or the effect is conditional on in vivo biological environments. Human umbilical vein endothelial cells (HUVEC) were collected and cultured from 89 normal deliveries of Mexican Americans. The cells were treated with or without cigarette smoking extracts (CSE) and genotypes of eNOS polymorphisms were determined by PCR. We measured the levels of eNOS by ELISA and its binding proteins including heat-shock protein 90 (Hsp-90) and caveolin-1 by Western blotting. The rare C allele for the promoter T786C polymorphism (0.2), and the rare 4 x 27-bp repeat allele in the intron 4 (0.30) were different from those reported in other populations. Yet, the rare T allele in the exon 7 (G894T polymorphism) was similar as others. After four passages in vitro, both the intron 4 and promoter polymorphisms maintained significant effects on eNOS mRNA levels in HUVECs (P < 0.05). However, the effects on eNOS protein and enzyme activity were less consistent. Although primary smokers had significantly lower eNOS protein levels (P < 0.05), the in vitro CSE treatment on cultured HUVECs only resulted in a significant reduction in NO levels as measured by the stable metabolites of nitrite/nitrate (P < 0.001). Neither Hsp-90 nor caveolin-1--important eNOS regulators--appears to mediate the genotypesmoking effects on eNOS expression although HUVECs did produce more Hsp-90 when exposed to CSE. Our study demonstrates that endothelial cells maintain genotype-dependent expression even after the deprivation of in vivo environment. However, the cigarette smoking-genotype interaction may require such in vivo conditions to be manifested.