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1.
We review the significance of two forms of sexual conflict (different evolutionary interests of the two sexes) for genetic differentiation of populations and the evolution of reproductive isolation. Conflicting selection on the alleles at a single locus can occur in males and females if the sexes have different optima for a trait, and there are pleiotropic genetic correlations between the sexes for it. There will then be selection for sex limitation and hence sexual dimorphism. This sex limitation could break down in hybrids and reduce their fitness. Pleiotropic genetic correlations between the sexes could also affect the likelihood of mating in interpopulation encounters. Conflict can also occur between (sex-limited) loci that determine behaviour in males and those that determine behaviour in females. Reproductive isolation may occur by rapid coevolution of male trait and female mating preference. This would tend to generate assortative mating on secondary contact, hence promoting speciation. Sexual conflict resulting from sensory exploitation, polyspermy and the cost of mating could result in high levels of interpopulation mating. If females evolve resistance to make pre- and postmating manipulation, males from one population could be more successful with females from the other, because females would have evolved resistance to their own (but not to the allopatric) males. Between-locus sexual conflict could also occur as a result of conflict between males and females of different populations over the production of unfit hybrids. We develop models which show that females are in general selected to resist such matings and males to persist, and this could have a bearing on both the initial level of interpopulation matings and the likelihood that reinforcement will occur. In effect, selection on males usually acts to promote gene flow and to restrict premating isolation, whereas selection on females usually acts in the reverse direction. We review theoretical models relevant to resolution of this conflict. The winning role depends on a balance between the ''value of winning'' and ''power'' (relating to contest or armament costs): the winning role is likely to correlate with high value of winning and low costs. Sperm-ovum (or sperm-female tract) conflicts (and their plant parallels) are likely to obey the same principles. Males may typically have higher values of winning, but it is difficult to quantify ''power'', and females may often be able to resist mating more cheaply than males can force it. We tentatively predict that sexual conflict will typically result in a higher rate of speciation in ''female-win'' clades, that females will be responsible for premating isolation through reinforcement, and that ''female-win'' populations will be less genetically diverse.  相似文献   

2.
Gerald Waring 《CMAJ》1967,97(4):192-195
In a national disaster, the medical profession would lose physicians and auxiliary personnel and would need assistance. Canada''s 22,000 physicians and 85,000 nurses are located for the most part in potential target areas. Survivors among Canada''s 6396 dentists could supply 30% reinforcement. The dentist''s training, his manual dexterity and experience acquired in the management of hemorrhage, shock, débridement, suturing, reduction and immobilization of fractures, and control of pain and infection would be valuable. Additional functions he could perform would be first-aid, including but not limited to artificial respiration, early management of chest wounds, preparation of casualties for movement, and assistance in general surgical procedures. Dentists with special training in anesthesia, oral surgery or public health could be of particular value in relieving anesthetists, surgeons, radiologists and public health officers of some of their duties. Joint training of physicians and dentists in mass casualty care could increase the efficiency of the team work in disaster and is being considered by many medical and dental faculties.  相似文献   

3.
K-Ras is a well-validated cancer target but is considered to be “undruggable” due to the lack of suitable binding pockets. We previously discovered small molecules that bind weakly to K-Ras but wanted to improve their binding affinities by identifying ligands that bind near our initial hits that we could link together. Here we describe an approach for identifying second site ligands that uses a cysteine residue to covalently attach a compound for tight binding to the first site pocket followed by a fragment screen for binding to a second site. This approach could be very useful for targeting Ras and other challenging drug targets.  相似文献   

4.
By encouraging and supporting general practitioners to undertake brief intervention on a routine basis smokers'' clinics could reach many more smokers than are willing to attend for intensive treatment. In a study with 101 general practitioners from 27 practices 4445 cigarette smokers received brief intervention with the support of a smokers'' clinic, brief intervention without such support, or the general practitioners'' usual care. At one year follow up the numbers of smokers who reported that they were no longer smoking cigarettes were 51 (13%), 63 (9%), and 263 (8%), respectively (p less than 0.005). After an adjustment was made for those cases not validated by urine cotinine concentrations the respective success rates were 8%, 5%, and 5%. Use of nicotine chewing gum was associated with higher self reported success rates. General practitioners providing supported brief intervention encouraged not only more smokers to use the gum but also more effective use; gum users in this group reported a success rate of 27% at one year. Compliance by the general practitioners in recording smoking state averaged 45%, and significantly higher success rates were reported by patients whose smoking state had been recorded. Brief intervention by general practitioners with the support of a smokers'' clinic thus significantly enhanced success rates based on self reports. Better results might be obtained if general practitioners'' compliance with the procedure could be improved and if they encouraged more of their patients to try nicotine gum. Collaboration of this kind between a smokers'' clinic and local general practitioners could deliver effective help to many more smokers than are likely to be affected if the two continue to work separately.  相似文献   

5.
OBJECTIVE--To identify aspects of outpatient referral in which general practitioners'', consultants'', and patients'' satisfaction could be improved. DESIGN--Questionnaire survey of general practitioners, consultant orthopaedic surgeons, and patients referred to an orthopaedic clinic. SETTING--Orthopaedic clinic, Doncaster Royal Infirmary. SUBJECTS--628 consecutive patients booked into the orthopaedic clinic. MAIN OUTCOME MEASURES--Views of the general practitioners as recorded both when the referral letter was received and again after the patient had been seen, views of the consultants as recorded at the time of the clinic attendance, and views of the patients as recorded immediately after the clinic visit and some time later. RESULTS--Consultants rated 213 of 449 referrals (42.7%) as possibly or definitely inappropriate, though 373 of 451 patients (82.7%) reported that they were helped by seeing the consultant. Targets for possible improvement included information to general practitioners about available services, communication between general practitioners and consultants, and administrative arrangements in clinics. Long waiting times were a problem, and it seemed that these might be reduced if general practitioners could provide more advice on non-surgical management. Some general practitioners stated that they would value easier telephone access to consultants for management advice. It was considered that an alternative source of management advice on musculoskeletal problems might enable more effective use to be made of specialist orthopaedic resources. Conclusion--A survey of patients'' and doctors'' views of referrals may be used to identify aspects in which the delivery of care could be made more efficient. Developing agreed referral guidelines might help general practitioners to make more effective use of hospital services.  相似文献   

6.
马晓菲  石龙宇 《生态学报》2020,40(22):8167-8175
雨洪径流失控引发的负面问题已经影响到城市居民的正常生活。雨水花园作为典型的用于雨洪治理的生态基础设施,是进行城市水管理的重要手段。为提升雨水花园以径流控制为主的生态系统服务能力,研究团队基于物联网技术在中科院城市所内建成一座带有径流控制效益监测系统的雨水花园研究示范样地。景感学作为研究生态系统服务和可持续发展的有效途径,基于其理论分析雨水花园样地这一景感的营造途径、原则、生态系统服务能力,有助于使人—生态基础设施—自然环境三者更和谐地相互融入和适应,进而为雨水花园这类生态基础设施的营造提供借鉴经验。经探究发现雨水花园样地营造遵循了愿景呈现的双向性、方位的顺脉性、营造过程的渐进性三项原则,它可从多方面提供调节服务、支持服务与文化服务,有利于改善区域人居环境。通过径流控制效益监测系统监测、分析得出样地具备显著的调节服务(径流削减)能力,且人们可通过视感、听感、触感感知并享受雨水花园样地供给的文化服务。由于物联网监测技术与居民对各部分生态系统服务的监测和感知能力各有侧重,本研究认为可结合物联网相关监测技术和人的物理感知对雨水花园这类生态基础设施的营造工作进行评估,进而指导这类生态基础设施的建...  相似文献   

7.
目的:加强对儿童巴特综合征药物治疗的认识,探讨医院药学部门的处方点评模式。方法:分析我院2015年12月的1张巴特综合征患者处方的合理性,并复习相关文献。结果:本张处方初评时被判定为不合理处方,经过临床药师与临床医师的沟通和查阅相关文献,复评时将此处方改判为合理处方,证明了我院三级处方点评模式可以提高药师审查处方的能力,确保处方点评合理、公平。结论:表面上看用药不合理的处方并不一定是真正的不合理,要深入分析处方的内涵,才能对处方进行准确的判定。三级处方点评模式能促进药师学习掌握专业知识技能,提高判断处方的能力。  相似文献   

8.
Over the past years, the substitution of the classical biochemical quantification techniques by Fourier transform infrared (FTIR) spectroscopy has been widely studied on microalgae because of its tremendous application potential for bioprocess monitoring. In the present work, mandatory aspects that have never been approached by FTIR end-users working onto fresh biomass were assessed. We demonstrated first that fresh cells’ FTIR spectra main characteristics could be severely and unspecifically altered when the properties of the sampled biomass were not monitored. Microscopy indicated that important cell reorganization could occur when diminishing the cells density of the sample. Molecular probing approach suggested that such a modification could provoke an alteration of the hydrogen-bonding network of the sample. The sample heterogeneity was found to impact also the shape and intensity of the recorded FTIR bands, participating then to a matrix effect uncharacterized until now. In the second part of our study, we selected FTIR spectra not influenced by this matrix effect and the corresponding accurate calibration data obtained by the whole cell analytical procedure to elaborate an optimized total lipid quantification PLS-R model. Results demonstrated that our strategy could provide a small volume sampling (1 mL of fresh culture), rapid (within minutes), robust (physiological condition independent), and accurate (as accurate as the reference method could be) FTIR absolute quantification method to determine the fresh microalgae intracellular total lipid content. To validate our unbiased FTIR approach, a photobioprocess monitoring pipeline was developed and allowed assessing the effect of light attenuation on total lipid production by the marine microalga Nannochloropsis oculata.  相似文献   

9.
中国生命周期评价理论与实践研究进展及对策分析   总被引:6,自引:0,他引:6  
王玉涛  王丰川  洪静兰  孙明星 《生态学报》2016,36(22):7179-7184
主要分析了我国生命周期评价的理论与实践研究进展与数据库构建现状,针对当前我国生命周期评价理论与应用研究的关键薄弱环节即不确定性分析、本土化数据库构建、本土化生命周期环境影响评价模型构建,指出了利用泰勒系列展开模型进行符合我国产业链生产现状的精确、完整、具有代表性、具有时空动态特征的生命周期数据库构建的必要性;并指出需要根据我国国情(例如:环境、地理、人口、暴露等)来构建生命周期环境影响评价模型的紧迫性。  相似文献   

10.
A detailed summary of the content and composition of total proteins, RNA and DNA in 57 yeast-like microorganisms is presented. On the basis of the correlation between the content of amino acids in proteins the studied strains could be divided into 8 groups that differ not only in the content of proteins and amino acids but also in the RNA and DNA content. According to this characteristic the groups ofBasidiomycetes andAscomycetes could be discriminated. The present study should also serve as orientation for the screening of strains suitable for the production of fodder yeasts.  相似文献   

11.
Ben Davies 《Bioethics》2016,30(6):462-468
Greg Bognar has recently offered a prioritarian justification for ‘fair innings’ distributive principles that would ration access to healthcare on the basis of patients' age. In this article, I agree that Bognar's principle is among the strongest arguments for age‐based rationing. However, I argue that this position is incomplete because of the possibility of ‘time‐relative' egalitarian principles that could complement the kind of lifetime egalitarianism that Bognar adopts. After outlining Bognar's position, and explaining the attraction of time‐relative egalitarianism, I suggest various ways in which these two kinds of principle could interact. Since various options have very different implications for age‐based rationing, proponents of such a rationing scheme must take a position on time‐relative egalitarianism to complement a lifetime prioritarian view like Bognar's.  相似文献   

12.
Clickers might own a bright future in China if properly introduced although they have not been widely acknowledged as an effective tool to facilitate English learning and teaching in Chinese contexts. By randomly selecting participants from undergraduates in a university in China over four academic years, this study aims to identify the impact of clickers on college English listening and speaking skills, and differences in cognitive loads between clickers and traditional multimedia assisted instruction modes. It was concluded that in China''s college English class, compared with multimedia assisted instruction, (1) clickers could improve college English listening skills; (2) clickers could improve college English speaking skills; and (3) clickers could reduce undergraduates'' cognitive loads in College English Class. Reasons for the results and defects in this study were also explored and discussed, based on learning, teaching and cognitive load theories. Some Suggestions for future research were also raised.  相似文献   

13.
While amphipols have been proven useful for refolding of seven transmembrane helical (7-TM) proteins including G-protein-coupled receptors (GPCRs) and it could be shown that an amphipol environment is in principle suitable for NMR structural studies of the embedded protein, high-resolution NMR insights into amphipol refolded and isotopically labeled GPCRs are still very limited. Here we report on the recent progress toward NMR structural studies of the melanocortin-2 and -4 receptors, two class A GPCRs which so far have not been reported to be incorporated into an amphipol environment. Making use of the established 7-TM protein bacteriorhodopsin (BR) we initially tested and optimized amphipol refolding conditions. Most promising conditions were transferred to the refolding of the two melanocortin receptors. Analytical-scale refolding experiments on the melanocortin-2 receptor show very similar behavior to the results obtained on BR. Using cell-free protein expression we could generate sufficient amounts of isotopically labeled bacteriorhodopsin as well as melanocortin-2 and -4 receptors for an initial NMR analysis. Upscaling of the amphipol refolding protocol to protein amounts needed for NMR structural studies was, however, not straightforward and impeded detailed NMR insights for the two GPCRs. While well-resolved and dispersed NMR spectra could only be obtained for bacteriorhodopsin, a comparison of NMR data recorded on the melanocortin-4 receptor in SDS and in an amphipol environment indicates that amphipol refolding induces larger structural modifications in the receptor.  相似文献   

14.
In a survey of the farming population of Orkney, Ayrshire, and East Lothian the prevalence of farmer''s lung was estimated at 86 per 1,000 in both Orkney and Ayrshire and 23 per 1,000 in East Lothian. If cases with a negative farmer''s lung hay (F.L.H.) precipitin test are excluded these figures are reduced to 43, 36, and nil respectively, but those for Orkney and Ayrshire are still about 20 times higher than any figure previously reported for the prevalence of farmer''s lung in Britain.Regional variations in prevalence are probably related both to climatic conditions and to differences in agricultural methods, the latter often being dictated by economic circumstances. Nevertheless the prevalence of farmer''s lung could be reduced considerably by the energetic application of preventive measures, backed by financial incentives. The most important of these are efficient drying of hay and cereals before storage, more extensive use of silage, better ventilation of farm buildings, and the introduction of mechanical feeding systems. Individual farmworkers could be taught how to recognize the early symptoms of the disease and encouraged to wear respirators when handling mouldy fodder.  相似文献   

15.
Translation of 2'-modified mRNA in vitro and in vivo.   总被引:1,自引:1,他引:0  
  相似文献   

16.
A necessary condition for a snowshoe hare population to cycle is reduced reproduction after the population declines. But the cause of a cyclic snowshoe hare population's reduced reproduction during the low phase of the cycle, when predator density collapses, is not completely understood. We propose that moderate‐severe browsing by snowshoe hares upon preferred winter‐foods could increase the toxicity of some of the hare's best winter‐foods during the following hare low, with the result being a decline in hare nutrition that could reduce hare reproduction. We used a combination of modeling and experiments to explore this hypothesis. Using the shrub birch Betula glandulosa as the plant of interest, the model predicted that browsing by hares during a hare cycle peak, by increasing the toxicity B. glandulosa twigs during the following hare low, could cause a hare population to cycle. The model's assumptions were verified with assays of dammarane triterpenes in segments of B. glandulosa twigs and captive hare feeding experiments conducted in Alaska during February and March 1986. The model's predictions were tested with estimates of hare density and measurements of B. glandulosa twig growth made at Kluane, Yukon from 1988–2008. The empirical tests supported the model's predictions. Thus, we have concluded that a browsing‐caused increase in twig toxicity that occurs during the hare cycle's low phase could reduce hare reproduction during the low phase of the hare cycle.  相似文献   

17.
Social cohesion and prey location in seabirds are largely enabled through visual and olfactory signals, but these behavioural aspects could potentially also be enhanced through acoustic transfer of information. Should this be the case, calling behaviour could be influenced by different social–ecological stimuli. African Penguins Spheniscus demersus were equipped with animal-borne video recorders to determine whether the frequency and types of calls emitted at sea were dependent on behavioural modes (commuting, sedentary and dive bout) and social status (solitary vs. group). For foraging dive bouts we assessed whether the timing and frequency of calls were significantly different in the presence of schooling prey vs. single fish. The probability of call events was significantly more likely for birds commuting early and late in the day (for solitary birds) and during dive bouts (for groups). During foraging dive bouts the frequency of calls was significantly greater for birds diving in the presence of schooling fish and birds called sooner after a catch in these foraging scenarios compared with when only single fish were encountered. Three call types were recorded, 'flat', 'modulated' and 'two-voice' calls, but there was no significant relationship detected with these call types and behavioural modes for solitary birds and birds in groups. The results of this study show that acoustic signalling by African Penguins at sea is used in a variety of behavioural contexts and that increased calling activity in the presence of more profitable prey could be of crucial importance to seabirds that benefit from group foraging.  相似文献   

18.
The archaeal phylum ‘Diapherotrites'' was recently proposed based on phylogenomic analysis of genomes recovered from an underground water seep in an abandoned gold mine (Homestake mine in Lead, SD, USA). Here we present a detailed analysis of the metabolic capabilities and genomic features of three single amplified genomes (SAGs) belonging to the ‘Diapherotrites''. The most complete of the SAGs, Candidatus ‘Iainarchaeum andersonii'' (Cand. IA), had a small genome (∼1.24 Mb), short average gene length (822 bp), one ribosomal RNA operon, high coding density (∼90.4%), high percentage of overlapping genes (27.6%) and low incidence of gene duplication (2.16%). Cand. IA genome possesses limited catabolic capacities that, nevertheless, could theoretically support a free-living lifestyle by channeling a narrow range of substrates such as ribose, polyhydroxybutyrate and several amino acids to acetyl-coenzyme A. On the other hand, Cand. IA possesses relatively well-developed anabolic capabilities, although it remains auxotrophic for several amino acids and cofactors. Phylogenetic analysis suggests that the majority of Cand. IA anabolic genes were acquired from bacterial donors via horizontal gene transfer. We thus propose that members of the ‘Diapherotrites'' have evolved from an obligate symbiotic ancestor by acquiring anabolic genes from bacteria that enabled independent biosynthesis of biological molecules previously acquired from symbiotic hosts. ‘Diapherotrites'' 16S rRNA genes exhibit multiple mismatches with the majority of archaeal 16S rRNA primers, a fact that could be responsible for their observed rarity in amplicon-generated data sets. The limited substrate range, complex growth requirements and slow growth rate predicted could be responsible for its refraction to isolation.  相似文献   

19.
目的:通过检测沙棘油作用高脂小鼠海马神经元内微管相关蛋白(Tau)及脑源性神经营养因子(BDNF)的表达水平,探讨沙棘油对高脂小鼠并发阿尔兹海默综合征的预防作用。方法:40只KM小鼠,随机取10只为正常对照组;30只以高脂饲料喂养建立高脂模型(HF),按10 mg/kg以生理盐水(阴性对照)、沙棘油(实验)、辛伐他丁(阳性对照)灌胃3 w。取小鼠海马组织进行HE染色、免疫组织化学检测和蛋白印迹分析,检测不同组别小鼠海马神经元内Tau蛋白及BDNF表达的变化。结果:高脂模型组与正常组比较,海马神经元结构在光镜下有明显差别;阴性对照组小鼠海马神经细胞数目减少,神经元内有黄色颗粒样沉淀;实验及阳性组海马损伤有改善,斑块状淀粉样蛋白减少;免疫组化及蛋白印迹显示各组间两种蛋白表达水平不同。结论:沙棘油对高脂小鼠海马体内Tau蛋白表达有抑制作用,加速淀粉样前体蛋白的代谢,降低了由β-淀粉样蛋白沉积诱发阿尔茨海默病的风险;而对BDNF表达有促进作用,能防止神经元受损伤死亡、改善神经元的病理状态、促进受损伤神经元再生。即沙棘油能有效预防高脂人群并发阿尔兹海默综合征。  相似文献   

20.
Absolute concentrations of total macromolecules (triglycerides, proteins and carbohydrates) in microorganisms can be rapidly measured by FTIR spectroscopy, but caution is needed to avoid non-specific experimental bias. Here, we assess the limits within which this approach can be used on model solutions of macromolecules of interest. We used the Bruker HTSXT-FTIR system. Our results show that the solid deposits obtained after the sampling procedure present physical and chemical properties that influence the quality of the absolute concentration prediction models (univariate and multivariate). The accuracy of the models was degraded by a factor of 2 or 3 outside the recommended concentration interval of 0.5–35 µg spot?1. Change occurred notably in the sample hydrogen bond network, which could, however, be controlled using an internal probe (pseudohalide anion). We also demonstrate that for aqueous solutions, accurate prediction of total carbohydrate quantities (in glucose equivalent) could not be made unless a constant amount of protein was added to the model solution (BSA). The results of the prediction model for more complex solutions, here with two components: glucose and BSA, were very encouraging, suggesting that this FTIR approach could be used as a rapid quantification method for mixtures of molecules of interest, provided the limits of use of the HTSXT-FTIR method are precisely known and respected. This last finding opens the way to direct quantification of total molecules of interest in more complex matrices.  相似文献   

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