三七、肉苁蓉、枸杞和黄芪总DNA提取方法的研究

本实验研究以中药材三七的叶子、肉苁蓉的茎、宁夏枸杞的果实、黄芪的根为材料,对改进CTAB法、SDS法提取的基因组DNA进行了比较研究.由于四种中药材所含成分有很大的差别,所得到的DNA样品在直观上也有很大的区别.结果表明,改良CTAB法适合四种中药材基因组DNA的提取.     

创新型文化及其构建——基于企业DNA理论的探讨

创新是企业获得竞争优势的源泉,丰硕的创新成果孕育于企业的创新文化。企业文化对创新活动既可能是支持性,也可能会产生消极的阻碍。创新型文化是一种激发、培育和实现创新的文化,创新型文化的形成必须有稳定的基础。创新文化的特征主要有:共同愿景和目标、信任与开放的氛围、鼓励冒险的精神、团队工作的方式、高层领导的支持和激励、宽容失败的态度等。根据企业DNA理论,创新型文化的建设要基于组织架构,决策权,信息传导和激励机制诸方面展开。     

存世曹氏族谱与曹操后裔无关——与复旦“曹操墓人类基因调查的历史学研究”课题组商榷

据陈寿所撰<三国志>载,曹操之父曹嵩乃中常侍曹腾之养子,其"生出本末"已不可考.春秋已降,就一直有"同姓不婚"的禁忌,夏侯与曹氏世为婚姻,故"曹氏源于夏侯氏"一说不能成立.目前国内所藏的家谱,宋代的极为罕见.大多数图书馆所藏的谱牒多为清代或民国时所修,明代族谱已不易见.存世曹氏族谱所录之远祖系唐末宋初人,与曹操时代相距近八百年.又由于历史上盛行冒姓、赐姓、改姓、认领养子、伪造谱牒之风,这就使今人寻求曹操后裔几无可能.     

Gender-dependent variations in systemic biomarkers of oxidative protein,DNA, and lipid damage in aged rats

Introduction.?The effect of aging on plasma-protein, lipid and DNA oxidation is well documented. However, none of the studies specify the effect of gender. The purpose of this study is to clarify the ambiguity raised in preliminary reports as to gender dependency of oxidative damage in plasma.

Methods.?In the current study, we investigated the relation between 8-hydroxy-2′-deoxyguanosine levels (8-OHdG), which is a measure of DNA oxidation and protein oxidation parameters such as protein carbonyl (PCO), total thiol (T-SH), and advanced oxidation protein products (AOPP). Our study also covered other oxidative stress parameters, such as lipid hydroperoxides (LHP), malondialdehyde (MDA), erythrocyte glutathione (GSH), superoxide dismutase (Cu-Zn SOD) and the catalase (CAT) activity in plasma of the male and female aged rats.

Results.?8-OHdG and MDA levels in male rats were significantly higher than those in the female group (p?<?0.01 for both parameters). T-SH levels were found to be higher in female rats than in the male (p?<?0.05). Plasma Cu-Zn SOD activities of male rats were significantly higher compared with those of the female rats (p?<?0.05). On the other hand, PCO, AOPP, LHP, GSH levels, and CAT activity were not found to be different between genders.

Conclusions.?We suggest that increased T-SH levels found in female rats may point to an adaptive reaction to oxidative damage, reflecting 8-OHdG and MDA overproduction. We are of the conviction that the increased 8-OHdG and MDA that we have determined in aged male rats may be a risk factor in the extent of oxidation in plasma.     

Interpreting forensic DNA mixtures: allowing for uncertainty in population substructure and dependence

We consider the assessment of deoxyribonucleic acid (DNA) profiles from biological samples containing a mixture of DNA from more than one person. The problem has been investigated in the context of likelihood ratios by Weir and co-workers under the assumption of independent alleles in DNA profiles. However, uncertainty about independence may arise from various factors such as population substructure and relatedness. This issue has received considerable attention in recent years. Ignoring this uncertainty may seriously overstate the strength of the evidence and therefore disadvantage innocent suspects. Taking this uncertainty into account, we develop a general formula for calculating the match probabilities of DNA profiles. Thus, we extend the result derived by Weir and co-workers to the dependence situation, which is often more to the benefit of the defendant in comparison with the simple product rule result based on an independence assumption. The effect of dependence of alleles on likelihood ratio estimates can be seen in the analysis of two real data sets.     

Limiting distribution of the number of clumps of palindromes in DNA

An important aspect in the analysis of long DNA sequences is to identify whether palindromes are over- or under-represented. The essential step in that direction is the analysis of the limiting distribution of the number of clumps of palindromes where clump is defined as the overlapping occurrence of palindromes. Using the Chen–Stein method, it is shown in this paper that the limiting distribution, under suitable conditions and a type of heterogeneous sequence, is the Poisson distribution. Moreover, error bounds and the rate of convergence are derived in terms of total variation distance between two probability distributions.     

The Identification of “Unusual” Health-Care Providers From a Hierarchical Model

It has become common to adopt a hierarchical model structure when comparing the performance of multiple health-care providers. This structure allows some variation in such measures, beyond that explained by sampling variation, to be “normal,” in recognition of the fact that risk-adjustment is never perfect. The shrinkage estimates arising from such a model structure also have appealing properties.

It is not immediately clear, however, how “unusual” providers, that is, any with particularly high or low rates, can be identified based on such a model. Given that some variation in underlying rates is assumed to be the norm, we argue that it is not generally appropriate to identify a provider as interesting based only on evidence of it lying above or below the population mean. We note with concern, however, that this practice is not uncommon.

We examine in detail three possible strategies for identifying unusual providers, carefully distinguishing between statistical “outliers” and “extremes.” A two-level normal model is used for mathematical simplicity, but we note that much of the discussion also applies to alternative data structures. Further, we emphasize throughout that each approach can be viewed as resulting from a Bayesian or a classical perspective. Three worked examples provide additional insight.     

A new hybrid estimation method for the generalized pareto distribution

ABSTRACT

The generalized Pareto distribution (GPD) is important in the analysis of extreme values, especially in modeling exceedances over thresholds. Most of the existing methods for estimating the scale and shape parameters of the GPD suffer from theoretical and/or computational problems. A new hybrid estimation method is proposed in this article, which minimizes a goodness-of-fit measure and incorporates some useful likelihood information. Compared with the maximum likelihood method and other leading methods, our new hybrid estimation method retains high efficiency, reduces the estimation bias, and is computation friendly.     

Unresolved issues in the forensic use of DNA profiling

The enormous amount of genetic diversity in humans allows for a powerful form of individual identification. This “DNA profiling”; is based on the fact that sites within the human genome have variable numbers of tandem repeats (VNTRs) and has been hailed in forensic sciences as the greatest discovery since fingerprinting. The techniques involved are virtually the same as those used in all molecular biology laboratories. A major difference however is that in forensic science DNA samples can be less than ideal in both quality and quantity. Furthermore, in basic molecular biology the origin of the sample is known while in forensic testing it is not. Thus, the challenge is to reconcile a “match”; between a crime scene DNA sample and one from a suspect(s). Presently, a debate exists regarding the use of the unmodified product rule versus a more conservative ceiling principle approach to calculate the probability of a coincidentally matching DNA profiles. The latter was endorsed in a recently published report by the prestigious National Research Council but has not received widespread support from testing laboratories. Further exacerbating the debate over how much weight should be attached to DNA profile evidence is a lack of widely accepted standards for forensic laboratories especially in the areas of proficiency testing, publication of error rates and laboratory personnel certification.     

Teaching about science

Science is one of the most exciting frontiers of human endeavor and yet is often poorly understood. In this article I argue that improved education of both our children and our adults is key for the future. It is incumbent on all scientists to help educate our citizenry. In addition to the traditional methods we should make better use of television for this purpose. I strongly advocate permeating regular news programs with science news and education.