变铅青链霉菌与放线菌噬菌体φHAU3相互关系的研究

变铅青链霉菌ＺＸ１,是由变铅青链霉菌ＪＴ４６经ＮＴＧ诱变后产生的一株修饰基因突变株,与其亲本ＪＴ４６相比,ＺＸ１除了与ＤＮＡ降解有关的基因发生了突变（Ｄｎｄ－,即该突变株的ＤＮＡ在含有Ｆｅ２＋的缓冲液中电泳不受到降解,而野生型变铅青链霉菌在同样条件下则遭到降解）以外,对噬菌体　ＨＡＵ３的抗性也随之消失,这项特征主要表现在噬菌斑大小和成斑单位（效价）上的显著变化。研究结果表明,噬菌体　ＨＡＵ３以同等的频率吸附野生型变铅青链霉菌及其突变菌株ＺＸ１,从　ＨＡＵ３基因组中没有克隆到被变铅青链霉菌识别的特异性靶位点;噬菌体ＨＡＵ３的ＤＮＡ也可以转染野生型变铅青链霉菌原生质,但其释放的噬菌体粒子只能感染突变菌株ＺＸ１,而不能感染野生型变铅青链霉菌。噬菌体ＨＡＵ３在突变株ＺＸ１中的繁殖遵循一步生长曲线,单菌释放量大约为１００,而　ＨＡＵ３感染野生型变铅青链霉菌后,则检测不到噬菌体的释放。     

Gene expression changes with age in skin,adipose tissue,blood and brain

Background

Previous studies have demonstrated that gene expression levels change with age. These changes are hypothesized to influence the aging rate of an individual. We analyzed gene expression changes with age in abdominal skin, subcutaneous adipose tissue and lymphoblastoid cell lines in 856 female twins in the age range of 39-85 years. Additionally, we investigated genotypic variants involved in genotype-by-age interactions to understand how the genomic regulation of gene expression alters with age.

Results

Using a linear mixed model, differential expression with age was identified in 1,672 genes in skin and 188 genes in adipose tissue. Only two genes expressed in lymphoblastoid cell lines showed significant changes with age. Genes significantly regulated by age were compared with expression profiles in 10 brain regions from 100 postmortem brains aged 16 to 83 years. We identified only one age-related gene common to the three tissues. There were 12 genes that showed differential expression with age in both skin and brain tissue and three common to adipose and brain tissues.

Conclusions

Skin showed the most age-related gene expression changes of all the tissues investigated, with many of the genes being previously implicated in fatty acid metabolism, mitochondrial activity, cancer and splicing. A significant proportion of age-related changes in gene expression appear to be tissue-specific with only a few genes sharing an age effect in expression across tissues. More research is needed to improve our understanding of the genetic influences on aging and the relationship with age-related diseases.     

<Emphasis Type="Italic">Bridelia stipularis</Emphasis>: a new source for anthocyanin production in vitro

The present study prospects Bridelia stipularis (L.) Blume as a new source of anthocyanins through leaf and internode explants-derived callus cultures. Murashige and Skoog (MS) medium fortified with 21.48 μM α-naphthaleneacetic acid was superior for callus growth. Of the different regimes, the anthocyanin production relied on synergic effects of plant growth regulators, pH, light, and carbon source. The calluses incubated in light on MS medium with 4% glucose containing 2.22 μM N⁶-benzyladenine (BA) and 2.26 μM 2,4-dichlorophenoxyacetic acid (2,4-D) at pH 3.5 yielded the highest amount (a mean of 0.42 mg g⁻¹ callus) of anthocyanins. Subsequent cultures of the calluses on the above medium yielded a stable production of anthocyanins. Medium containing glucose was superior to that with sucrose for anthocyanin formation. Kinetin was inhibitory to anthocyanin accumulation. Suspension cultures of MS medium containing 2.26 μM 2,4-D and 2.22 μM BA at pH 5.0 started excretion of anthocyanins into the medium on reaching to pH 4.4–4.6.     

Limited Density of an Antigen Presented by RMA-S Cells Requires B7-1/CD28 Signaling to Enhance T-Cell Immunity at the Effector Phase

The association of B7-1/CD28 between antigen presenting cells (APCs) and T-cells provides a second signal to proliferate and activate T-cell immunity at the induction phase. Many reports indicate that tumor cells transfected with B7-1 induced augmented antitumor immunity at the induction phase by mimicking APC function; however, the function of B7-1 on antitumor immunity at the effector phase is unknown. Here, we report direct evidence of enhanced T-cell antitumor immunity at the effector phase by the B7-1 molecule. Our experiments in vivo and in vitro indicated that reactivity of antigen-specific monoclonal and polyclonal T-cell effectors against a Lass5 epitope presented by RMA-S cells is increased when the cells expressed B7-1. Use of either anti-B7-1 or anti-CD28 antibodies to block the B7-1/CD28 association reduced reactivity of the T effectors against B7-1 positive RMA-S cells. Transfection of Lass5 cDNA into or pulse of Lass5 peptide onto B7-1 positive RMA-S cells overcomes the requirement of the B7-1/CD28 signal for T effector response. To our knowledge, the data offers, for the first time, strong evidence that supports the requirement of B7-1/CD28 secondary signal at the effector phase of antitumor T-cell immunity being dependent on the density of an antigenic peptide.     

Two percent of men with early-onset prostate cancer harbor germline mutations in the BRCA2 gene

Studies of families with breast cancer have indicated that male carriers of BRCA2 mutations are at increased risk of prostate cancer, particularly at an early age. To evaluate the contribution of BRCA2 mutations to early-onset prostate cancer, we screened the complete coding sequence of BRCA2 for germline mutations, in 263 men with diagnoses of prostate cancer who were 相似文献   

A new nonhydrolyzable reactive cAMP analog, (Sp)-adenosine-3',5'-cyclic-S-(4-bromo-2,3-dioxobutyl)monophosphorothioate irreversibly inactivates human platelet cGMP-inhibited cAMP phosphodiesterase

Levels of cAMP that control critical platelet functions are regulated by cGMP-inhibited cAMP phosphodiesterase (PDE3A). We previously showed that millimolar concentrations of the hydrolyzable 8-[(4-bromo-2,3-dioxobutyl)thioadenosine 3',5'-cyclic monophosphate (8-BDB-TcAMP) inactivate PDE3A. We have now synthesized a nonhydrolyzable affinity label to probe the active site of PDE3A. The nonhydrolyzable adenosine 3',5'-cyclic monophosphorothioates, Sp-cAMPS and Rp-cAMPS, function as competitive inhibitors of PDE3A with K(i) = 47.6 and 4400 microM, respectively. We therefore coupled Sp-cAMPS with 1,4-dibromobutanedione to yield (Sp)-adenosine-3',5'-cyclic-S-(4-bromo-2,3-dioxobutyl)monophosphorothioate, [Sp-cAMPS-(BDB)]. Sp-cAMPS-(BDB) inactivates PDE3A in a time-dependent, irreversible reaction with k(max) = 0.0116 min(-1) and K(I) = 10.1 microM. The order of effectiveness of protectants in decreasing the rate of inactivation (with K(d) in microM) is: Sp-cAMPS (24) > Rp-cGMPS (1360), Sp-cGMPS (1460) > GMP (4250), AMP (10600), Rp-cAMPS (22170). These results suggest that the inactivation of PDE3A by Sp-cAMPS-(BDB) is a consequence of reaction at the overlap of the cAMP and cGMP binding regions in the active site.     

Suitability of UK Biobank Retinal Images for Automatic Analysis of Morphometric Properties of the Vasculature

PurposeTo assess the suitability of retinal images held in the UK Biobank - the largest retinal data repository in a prospective population-based cohort - for computer assisted vascular morphometry, generating measures that are commonly investigated as candidate biomarkers of systemic disease.MethodsNon-mydriatic fundus images from both eyes of 2,690 participants - people with a self-reported history of myocardial infarction (n=1,345) and a matched control group (n=1,345) - were analysed using VAMPIRE software. These images were drawn from those of 68,554 UK Biobank participants who underwent retinal imaging at recruitment. Four operators were trained in the use of the software to measure retinal vascular tortuosity and bifurcation geometry.ResultsTotal operator time was approximately 360 hours (4 minutes per image). 2,252 (84%) of participants had at least one image of sufficient quality for the software to process, i.e. there was sufficient detection of retinal vessels in the image by the software to attempt the measurement of the target parameters. 1,604 (60%) of participants had an image of at least one eye that was adequately analysed by the software, i.e. the measurement protocol was successfully completed. Increasing age was associated with a reduced proportion of images that could be processed (p=0.0004) and analysed (p<0.0001). Cases exhibited more acute arteriolar branching angles (p=0.02) as well as lower arteriolar and venular tortuosity (p<0.0001).ConclusionsA proportion of the retinal images in UK Biobank are of insufficient quality for automated analysis. However, the large size of the UK Biobank means that tens of thousands of images are available and suitable for computational analysis. Parametric information measured from the retinas of participants with suspected cardiovascular disease was significantly different to that measured from a matched control group.     

香菇的学名及其在当代真菌分类中的位置

本文综述了香菇(Lentinula edodes)的分类历史,确认其在蘑菇目(Agaricales)Tricholomataceae科下的分类地位,并证实了它与多孔菌目(Poriales)Lentinaceae科的Lentinus属没有联系。根据《真菌、地衣汉语学名命名法规》,作者讨论了译为“香菇属”的Lentinus和“小香菇属”的Lentinellus两属的汉语学名问题,提出Lentinus的汉语学名应订正为“韧伞属”,Lentinellus为“螺壳菌属”。香菇所在的Lentinula属的汉语学名建议为“木菇属”。     

The many roles of small RNAs in leaf development

Leaf development involves many complex genetic interactions,signals between adjacent cells or between more distant tissues and consequent changes in cell fate.This review describes three stages in leaf development where regulation by small RNAs have been used to modulate gene expression patterns.