Character displacement drives floral variation in Pelargonium (Geraniaceae) communities

Interactions between plant community members are an underexplored driver of angiosperm floral variation. We investigate character displacement as a potential contributor to floral variation in Pelargonium communities. Pelargoniums all place pollen on the ventral sides of their pollinators, potentially leading to interspecific pollen transfer (IPT) in sympatry. We show that the positions of pollen placement and receipt are determined by anther and style exsertion lengths. Using field experiments, we demonstrate that heterospecific species experience higher IPT if they have similar style lengths than when they have greater style length differences. Using crosses, we show that IPT has negative consequences on seed set. In combination, these results suggest that character displacement in style length is likely to reduce IPT and increase female fitness in sympatry. Patterns of style length variation across 29 different Pelargonium communities suggest that character displacement has occurred in multiple communities. Furthermore, analyses using a wide-ranging species pair show that style lengths are more different between sympatric populations than they are between allopatric populations. In addition to pollinators as agents of floral divergence, this study suggests that variation in Pelargonium community structure has driven style length variation through character displacement.     

Comparing methods for metabolic network analysis and an application to metabolic engineering

Bioinformatics tools have facilitated the reconstruction and analysis of cellular metabolism of various organisms based on information encoded in their genomes. Characterization of cellular metabolism is useful to understand the phenotypic capabilities of these organisms. It has been done quantitatively through the analysis of pathway operations. There are several in silico approaches for analyzing metabolic networks, including structural and stoichiometric analysis, metabolic flux analysis, metabolic control analysis, and several kinetic modeling based analyses. They can serve as a virtual laboratory to give insights into basic principles of cellular functions. This article summarizes the progress and advances in software and algorithm development for metabolic network analysis, along with their applications relevant to cellular physiology, and metabolic engineering with an emphasis on microbial strain optimization. Moreover, it provides a detailed comparative analysis of existing approaches under different categories.     

哺乳期BALB/c小鼠胆道梗阻模型的探索

目的探讨新生BALB/c小鼠胆道梗阻模型的建立,并与报告的新生BALB/c小鼠感染猕猴轮状病毒(RRV)模型小鼠生存曲线进行比较。方法将出生后5～7 d的BALB/c小鼠随机分为实验组和对照组,实验组进行胆总管结扎,然后关腹。对照组打开腹部后关腹不结扎胆总管。实验完成后每天观察小鼠的体重变化、无毛区皮肤颜色变化、小鼠存活天数以及在术后第5、10天时分别取小鼠肝脏做病理及免疫组化。结果小鼠在结扎后随着时间的延长,小鼠的体重及肝体比、无毛区皮肤颜色、存活天数、肝脏病理等都存在一定变化。小鼠体重增长逐渐缓慢,术后第2天就会出现无毛区的皮肤变黄,在尿道口会有淡黄色的液体并随后出现陶土样便。在术后第5天及第10天时取肝脏做肝体比有统计学差异(P≤0.05),小鼠在术后第10天左右会出现死亡高峰。结论新生BALB/c小鼠胆总管结扎模型是研究胆道梗阻的可靠动物实验,其生存曲线与报告的猕猴轮状病毒致胆道闭锁大体类似。     

Floral specialization for different pollinators and divergent use of the same pollinator among co‐occurring Impatiens species (Balsaminaceae) from Southeast Asia

Floral variation among closely related species is thought to often reflect differences in pollination systems. Flowers of the large genus Impatiens are characterized by extensive variation in colour, shape and size and in anther and stigma positioning, but studies of their pollination ecology are scarce and most lack a comparative context. Consequently, the function of floral diversity in Impatiens remains enigmatic. This study documents floral variation and pollination of seven co‐occurring Impatiens spp. in the Southeast Asian diversity hotspot. To assess whether floral trait variation reflects specialization for different pollination systems, we tested whether species depend on pollinators for reproduction, identified animals that visit flowers, determined whether these visitors play a role in pollination and quantified and compared key floral traits, including floral dimensions and nectar characteristics. Experimental exclusion of insects decreased fruit and seed set significantly for all species except I. muscicola, which also received almost no visits from animals. Most species received visits from several animals, including bees, birds, butterflies and hawkmoths, only a subset of which were effective pollinators. Impatiens psittacina, I. kerriae, I. racemosa and I. daraneenae were pollinated by bees, primarily Bombus haemorrhoidalis. Impatiens chiangdaoensis and I. santisukii had bimodal pollination systems which combined bee and lepidopteran pollination. Floral traits differed significantly among species with different pollination systems. Autogamous flowers were small and spurless, and did not produce nectar; bee‐pollinated flowers had short spurs and large floral chambers with a wide entrance; and bimodally bee‐ and lepidopteran‐pollinated species had long spurs and a small floral chamber with a narrow entrance. Nectar‐producing species with different pollination systems did not differ in nectar volume and sugar concentration. Despite the high frequency of bee pollination in co‐occurring species, individuals with a morphology suggestive of hybrid origin were rare. Variation in floral architecture, including various forms of corolla asymmetry, facilitates distinct, species‐specific pollen‐placement on visiting bees. Our results show that floral morphological diversity among Impatiens spp. is associated with both differences in functional pollinator groups and divergent use of the same pollinator. Non‐homologous mechanisms of floral asymmetry are consistent with repeated independent evolution, suggesting that competitive interactions among species with the same pollination system have been an important driver of floral variation among Impatiens spp.     

Protein side chain conformation predictions with an MMGBSA energy function

The prediction of protein side chain conformations from backbone coordinates is an important task in structural biology, with applications in structure prediction and protein design. It is a difficult problem due to its combinatorial nature. We study the performance of an “MMGBSA” energy function, implemented in our protein design program Proteus, which combines molecular mechanics terms, a Generalized Born and Surface Area (GBSA) solvent model, with approximations that make the model pairwise additive. Proteus is not a competitor to specialized side chain prediction programs due to its cost, but it allows protein design applications, where side chain prediction is an important step and MMGBSA an effective energy model. We predict the side chain conformations for 18 proteins. The side chains are first predicted individually, with the rest of the protein in its crystallographic conformation. Next, all side chains are predicted together. The contributions of individual energy terms are evaluated and various parameterizations are compared. We find that the GB and SA terms, with an appropriate choice of the dielectric constant and surface energy coefficients, are beneficial for single side chain predictions. For the prediction of all side chains, however, errors due to the pairwise additive approximation overcome the improvement brought by these terms. We also show the crucial contribution of side chain minimization to alleviate the rigid rotamer approximation. Even without GB and SA terms, we obtain accuracies comparable to SCWRL4, a specialized side chain prediction program. In particular, we obtain a better RMSD than SCWRL4 for core residues (at a higher cost), despite our simpler rotamer library. Proteins 2016; 84:803–819. © 2016 Wiley Periodicals, Inc.     

覆膜支架腔内修复术与药物保守治疗对Stanford B型主动脉夹层动脉瘤患者肝肾功能、炎性因子以及预后的影响

目的:比较覆膜支架腔内修复术与药物保守治疗对Standford B型主动脉夹层动脉瘤的疗效及对患者肝肾功能、炎性因子及预后的影响。方法:选择2012年1月～2014年8月我院收治的Standford B型主动脉夹层动脉瘤患者68例,按照随机数字表法分为对照组与研究组,各34例。对照组入院后采取药物保守治疗,研究组应用覆膜支架腔内修复术治疗。观察两组住院期间死亡率、再次手术或介入率以及治疗前、治疗2周后肝肾功能、血清炎性因子变化。所有患者随访36个月,比较两组患者预后情况。结果:研究组再次手术或介入率为2.94%,低于对照组的22.58%(P0.05)。治疗2周后,研究组丙氨酸转氨酶(ALT)、天门冬氨酸氨基转移酶(AST)、尿素氮(BUN)、肌酐(Cr)、胱抑素C、肿瘤坏死因子-α(TNF-α)、白细胞介素-1β(IL-1β)、γ-干扰素(INF-γ)、C反应蛋白(CRP)水平较治疗前降低(P0.05),且研究组低于对照组(P0.05)。两组患者均随访36个月,随访12个月时两组患者生存率分别为100.00%和80.65%,随访36个月时两组患者生存率分别为91.18%和29.03%,经Log Rank分析显示,两组生存率比较差异有统计学意义(P0.05)。结论:覆膜支架腔内修复术治疗Standford B型主动脉夹层动脉瘤的疗效确切,能够改善患者肝肾功能,降低炎症反应,患者近中期随访生存率较高,其效果优于保守治疗。     

胆囊切除术医源性胆管损伤的处理

目的:探讨开腹胆囊切除术医源性胆道损伤的诊断、手术时机和手术方式的选择。方法:对18例胆道损伤进行分析总结:分别施行了胆管修补、T管引流术10例,保守治疗2例,Roux-en-Y胆肠吻合术6例。结果:3例术后过早拔管发生吻合口狭窄,再次手术。1例因梗阻性胆管炎并发肝功能衰竭、多器官功能衰竭死亡。1例因胆肠吻合术后并发消化道出血、肝昏迷死亡。余术后良好。结论:尽早发现及正确处理对提高疗效和预防术后胆管狭窄起着决定性的作用。术中发现胆管损伤立即行端端吻合加T管引流;术后数天发现或多次胆道修补术失败者,则宜行规范的Roux-en-Y胆肠吻合术。     

Correlations of pelvis state to foot placement do not imply within-step active control

Experimental studies of human walking have shown that within an individual step, variations in the center of mass (CoM) state can predict corresponding variations in the next foot placement. This has been interpreted by some to indicate the existence of active control in which the nervous system uses the CoM state at or near mid-stance to regulate subsequent foot placement. However, the passive dynamics of the moving body and/or moving limbs also contribute (perhaps strongly) to foot placement, and thus to its variation. The extent to which correlations of CoM state to foot placement reflect the effects of within-step active control, those of passive dynamics, or some combination of both, remains an important and still open question. Here, we used an open-loop-stable 2D walking model to show that this predictive ability cannot by itself be taken as evidence of within-step active control. In our simulations, we too find high correlations between the CoM state and subsequent foot placement, but these correlations are entirely due to passive dynamics as our system has no active control, either within a step or between steps. This demonstrates that any inferences made from such correlations about within-step active control require additional supporting evidence beyond the correlations themselves. Thus, these within-step predictive correlations leave unresolved the relative importance of within-step active control as compared to passive dynamics, meaning that such methods should be used to characterize control in human walking only with caution.     

The role of mitochondria in sepsis-induced cardiomyopathy

Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. Myocardial dysfunction, often termed sepsis-induced cardiomyopathy, is a frequent complication and is associated with worse outcomes. Numerous mechanisms contribute to sepsis-induced cardiomyopathy and a growing body of evidence suggests that bioenergetic and metabolic derangements play a central role in its development; however, there are significant discrepancies in the literature, perhaps reflecting variability in the experimental models employed or in the host response to sepsis. The condition is characterised by lack of significant cell death, normal tissue oxygen levels and, in survivors, reversibility of organ dysfunction. The functional changes observed in cardiac tissue may represent an adaptive response to prolonged stress that limits cell death, improving the potential for recovery. In this review, we describe our current understanding of the pathophysiology underlying myocardial dysfunction in sepsis, with a focus on disrupted mitochondrial processes.