Alternative mating tactics and extreme male dimorphism in fig wasps

The dimorphisms in morphology and behaviour of male fig wasps are among the most extreme in the animal kingdom, and offer excellent opportunities to test the predictions of certain sexual selection models. Winged males resemble their conspecific females closely, but wingless males are so divergent in form that they have repeatedly been classified into different taxa. Wingless males mate within their natal fig fruits, whereas winged males disperse to mate. Individual species may have winged males, wingless males or both morphs. A key hypothesis proposes that sexual selection on male mating opportunities favours winged males in species with small broods and wingless males in species with large broods. Using data from 114 species in 33 genera, we show that both simple and formal comparative analyses support the correlated evolution of large brood size and male winglessness. Theoretical models further predict that, in male dimorphic species, the proportion of winged males should equal (in cases without local mate competition) or exceed (in cases with local mate competition) the proportion of females developing in fig fruits without wingless males. These predictions are met by eight out of nine male dimorphic species studied. Taken together, the patterns across all species, and between different male dimorphic species, strongly support sexual selection on mating opportunities as the major determinant of male morph ratios in fig wasps.     

Molecular Biomarkers of Pancreatic Intraepithelial Neoplasia and Their Implications in Early Diagnosis and Therapeutic Intervention of Pancreatic Cancer

Lack of early detection and effective interventions is a major reason for the poor prognosis and dismal survival rates for pancreatic cancer. Pancreatic intraepithelial neoplasia (PanIN) is the most common precursor of invasive pancreatic ductal adenocarcinoma (PDAC). Each stage in the progression from PanIN to PDAC is well characterized by multiple significant genetic alterations affecting signaling pathways. Understanding the biological behavior and molecular alterations in the progression from PanIN to PDAC is crucial to the identification of noninvasive biomarkers for early detection and diagnosis and the development of preventive and therapeutic strategies for control of pancreatic cancer progression. This review focuses on molecular biomarkers of PanIN and their important roles in early detection and treatment of pancreatic cancer.     

Nothing reliable about genes or environment: new perspectives on analysis of similarity among relatives in light of the possibility of underlying heterogeneity

Despite the long history of scientific, philosophical, and political debate around heritability studies, certain fundamental conceptual issues have not been recognized or well appreciated. The starting point is that heritability does not measure the degree of influence that genes have on a trait or provide a reliable basis for choosing which traits to investigate further with molecular genetic research. (Similarly, for equivalent interpretations of shared and non-shared environmental effects in studies of human variation.) The short argument on this point revolves around two issues: the disconnect between analyzing measurements of a trait and exposing the measurable genetic and environmental factors underlying the trait’s development; and the possibility of heterogeneity in these underlying factors, that is, different factors may lead to the same trait value. The idea of underlying heterogeneity is elaborated through schematic diagrams and distinguished from other senses of heterogeneity. Five conceptually distinct approaches for addressing underlying heterogeneity are identified, corresponding to distinct ways of managing the reciprocal relationship between the degree of knowledge of the dynamics through which the trait develops and the actions that can be reliably be based on what is known (or unknown). This framework, which extends the interventionist notion of causality, allows the scope and limitations of heritability studies to be clarified in greater detail. It can also inform critical appreciation of newer methods of analysis of genetic and environmental factors. The issues discussed in this article do not centre on empirical data or technical detail and should be accessible to non-specialists as well as challenging active researchers.     

Glucosinolates, isothiocyanates and human health

Concurrent with the increase in our knowledge of the genetic and environmental factors that lead to glucosinolate accumulation in plants, and the role of these compounds and their derivatives in mediating plant–herbivore interactions, there has been significant advances in our understanding of how glucosinolates and their products may contribute to a reduction in risk of carcinogenesis and heart disease when consumed as part of the diet. In this paper, we review the epidemiological evidence for the health promoting effects of cruciferous vegetables, the processes by which glucosinolates and isothiocyanates are absorbed and metabolised by humans, with particular regard to the role of glutathione S-transferases, and the biological activity of isothiocyanates towards mammalian cells and tissues.     

Folate intake and bowel cancer risk

Folate is a B vitamin required for one-carbon transfer reactions including methylation of cell macromolecules including DNA and synthesis of the purines adenosine and guanosine and the pyrimidine thymidine. Epidemiological evidence suggests that diets providing higher amounts of folates lower the risk of colo-rectal cancer (CRC) and these observations are supported by plausible biological mechanisms. Inadequate folate supply results in DNA damage through (a) the incorporation of uracil (in place of thymidine) into DNA and subsequent unsuccessful attempts at DNA repair and (b) aberrant patterns of DNA methylation. However, human intervention studies using relatively large doses (500–5,000 μg/day) of folic acid (a synthetic form of folate) have provided no evidence of benefit in terms of adenoma recurrence. Indeed, there is some evidence of potential harm in increased risk of prostate cancer. Possible reasons for the apparent divergence in findings from the observational and intervention studies include the use of (unphysiologically) large doses of folic acid in the intervention studies whereas smaller intakes of food folates appeared to offer “protection” against CRC in case–control and prospective cohort studies. With intakes of folic acid greater than 400 μg/day, unmetabolised folic acid appears in peripheral blood and there are suggestions that this folic acid may have adverse effects e.g. reduced cytotoxicity of Natural Killer cells. Until the benefit-risk relationship associated with mandatory fortification with folic acid has been clarified (and, in particular, the possible risk of inducing extra cases of bowel or other cancer), it would seem wise to delay further mandatory folic acid fortification.     

The cost of dishonesty

The handicap principle states that stable biological signals must be honest and costly to produce. The cost of the signal should reflect the true quality of the signaller. Here, it is argued that honest signalling may be maintained although the used signals are not handicaps. A game theoretic model in the form of a game of signalling is presented: all the existing evolutionarily stable strategies (ESSs) are found. Honest and cheap signalling of male quality is shown to be evolutionarily stable if females divorce the mate if it turns out that he has cheated about his quality. However, for this ESS to apply, the cost of lost time must not be too great. The stability of the honest signalling is based on deceivers being prevented from spreading in the population because they suffer from a cost of divorce. Under some fairly strict conditions, a mixed polymorphism of dishonesty and honesty represents another possible ESS.     

肿瘤干细胞及其模型的研究现状及临床治疗最新进展

癌症发生最有名的模型之一肿瘤CSCcancer stem cell(CSC)模型已经被确立为一种细胞机制,有助于体现不同类型的肿瘤表型和功能的异质性。然而,最新研究突出显示了肿瘤CSC模型的复杂性和挑战性:CSC表型在不同的病人间有本质上的不同,肿瘤可能含有多种表型或遗传上不同的CSC,转移的肿瘤CSC可能由原始肿瘤CSC进展而来,肿瘤细胞可进行可逆的表型的改变。虽然在特定情况下,肿瘤CSC的概念具有临床相关性,但越来越多的证据表明,定位、鉴定出肿瘤灶中所有亚型的肿瘤CSC将对临床上预防肿瘤复发具有特殊意义。有以下几个因素可以促使异质性的发生:基因突变,后生的变化,与微环境间的相互作用以及存在或缺失细胞分级等。肿瘤异质性可以用不同的细胞机制来解释。虽然CSC具有CSC自我更新和分化的特性,但是它们不一定是正常组织CSC转化而形成的。这种CSC模型引起了科研工作者广泛的关注,我们结合新近的相关文献综述如下。     

高龄ST段抬高心肌梗死患者经皮冠状动脉介入术后的院内预后及其影响因素分析

目的:探讨高龄ST段抬高心肌梗死(STEMI)患者行直接经皮冠状动脉介入(PCI)术后住院期间的预后情况及其影响因素。方法:回顾性分析2009年1月至2013年12月因STEMI入住我院并行直接PCI的高龄患者(年龄≥75岁)的一般情况、既往史、入院情况、术中及术后情况、并发症等资料,总结分析该类患者住院期间的临床预后,并采用logistic回归模型对可能影响住院期间主要不良心脏事件(MACE)的危险因素进行分析。结果:研究共纳入127例患者,其中男性84例(66.14%),女性43例(33.86%),年龄79±3岁,住院时间13.07±7.80天,住院期间MACE的发生率为17.32%,其中死亡4例(3.15%)。单因素logistic回归分析显示入院时心功能(Killip分级)≥2级、完全性房室传导阻滞、窦性停搏与高龄STEMI患者直接PCI术后住院期间MACE的发生相关,具有统计学意义(P0.05)。而多因素logistic回归分析显示入院时心功能(Killip分级)和完全性房室传导阻滞是高龄STEMI患者住院期间MACE的危险因素。结论:高龄STEMI患者接受直接PCI治疗总体安全,影响其住院期间MACE的危险因素包括心功能不全和完全性房室传导阻滞。     

术前参观对冠状动脉介入治疗患者焦虑的影响

目的:探讨术前参观对择期进行心脏介入术患者心理焦虑的影响。方法:将400例择期行心脏介入手术的患者分为参观组和对照组,对照组术前采用常规护理干预,参观组患者在此基础上进行术前参观,熟悉环境,了解手术过程。调查比较两组患者术前2日及术前1小时的焦虑值。结果:参观组与对照组术前2日焦虑值无明显差异,术前1小时参观组焦虑值明显低于对照组,差异具有统计学意义(P0.05)。结论:通过术前参观能够减轻患者的焦虑程度。     

Sampling-rate-dependent probabilistic Boolean networks

External control of a genetic regulatory network is used for the purpose of avoiding undesirable states, such as those associated with a disease. To date, intervention has mainly focused on the external control of probabilistic Boolean networks via the associated discrete-time discrete-space Markov processes. Implementation of an intervention policy derived for probabilistic Boolean networks requires nearly continuous observation of the underlying biological system since precise application requires the observation of all transitions. In medical applications, as in many engineering problems, the process is sampled at discrete time intervals and a decision to intervene or not must be made at each sample point. In this work, sampling-rate-dependent probabilistic Boolean network is proposed as an extension of probabilistic Boolean network. The proposed framework is capable of capturing the sampling rate of the underlying system.