首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
This is a review of the film Through These Eyes , by Charles Laird. The film explores the historical moment during the Cold War in which the National Science Foundation funded educational curricula and programs to advance education in the sciences. Through These Eyes focuses on the history of one course of study as a part of these programs, a year-long course called "Man, a Course of Study" that presented fifth-grade students with materials designed to have them explore what it means to be a human being, by combining biology, primatology, and some anthropology.  相似文献   

2.
This article explores the interplay between culture and Christianity by detailing the history, experience, and impact of the Charismatic Catholic Renewal in the Autonomous Region of Bougainville in Papua New Guinea (PNG). In 1985, the PNG Catholic Bishops' Conference approved the charismatic movement as one of the authentic movements for spiritual renewal of the Catholic Church in PNG. However, the conference stressed this renewal not to be made independent or outside of the Church. In this article I discuss how in Bougainville the Catholic Charismatic Renewal (CCR) has been predominantly operating ‘outside’ the institutional Catholic Church, drawing upon both Catholic and cultural logics to mobilise devotees across Bougainville towards renewal and political change. In particular, I will focus on various local Marian movements, elucidating the power and force of the CCR in contexts of Bougainville's civil war (1988–1998). In doing so, this paper will explore what Catholicism and CCR may contribute to discussions about the positioning of culture within Christianity, at the same time showing how charismatic Marian devotion invites reassessment of recent prevailing discussions on cultural ‘continuity’ versus ‘rupture’, as well as doctrinal boundaries held so dearly by the CCR and the Roman Catholic Church in general.  相似文献   

3.
4.
Bacterial toxin-antitoxin (TA) systems are operons that code for a stable toxic protein and a labile antitoxin. TA modules are widespread on the chromosomes of free-living Bacteria and Archaea, where they presumably act as stress response elements. The chromosome of Escherichia coli K-12 encodes four known TA pairs, as well as the dinJ-yafQ operon, which is hypothesized to be a TA module based on operon organization similar to known TA genes. Induction of YafQ inhibited cell growth, but its toxicity was counteracted by coexpression of dinJ cloned on a separate plasmid. YafQ(His)(6) and DinJ proteins coeluted in Ni(2+)-affinity and gel filtration chromatography, implying the formation of a specific and stable YafQ-DinJ protein complex with an estimated molecular mass of c. 37.3 kDa. Induction of YafQ reduced protein synthesis up to 40% as judged by incorporation of [(35)S]-methionine, but did not influence the rates of DNA and RNA synthesis. Structure modelling of E. coli YafQ revealed its structural relationship with bacterial toxins of known structure suggesting that it might act as a sequence-specific mRNA endoribonuclease.  相似文献   

5.
Benzoic acid, sulfosalicylic acid and methyl salicylic acid wereevaluated for their regulatory role in inducing multiple stress tolerance inbean (Phaseolus vulgaris cv Brown Beauty) and tomato(Lycopersicum esculentum cv Romano) plants. All threemolecules were effective in inducing tolerance to heat, drought and chillingstress similar to that reported previously for salicylic and acetylsalicylicacids. Benzoic acid is effective at lower concentrations than salicylic acid orits derivatives. The benzoic acid structural portion is common to all fivemolecules and is the most likely basic functional molecular structure impartingstress tolerance in plants.  相似文献   

6.
Golden egg bug Phyllomorpha laciniata (Heteroptera, Coreidae) females oviposit on male and female conspecifics that carry ova until they hatch. Embryos benefit from being carried because of diminished risks of predation. Female carriers are never the parents of carried eggs, and males are only rarely the fathers of any carried eggs. Eggs develop and hatch without being carried in the laboratory. Egg carriers may be viewed as victims, exploited by females that encumber them with eggs. The intensity of selection favouring resistance to egg carrying should be proportional to the costs of this behaviour. One possible cost could be a reduction in mobility caused by carried eggs. We compare movement rates among encumbered and unencumbered golden egg bugs of both sexes. Protracted copulations (often exceeding 20 h) typical of this species and mating may also cause reduction in bugs mobility. Therefore, we also evaluate rates of movement of coupled pairs of bugs. Our results indicate that egg loads do not affect the mobility and speed of either males or females. However, copulating pairs are significantly slowed as compared to single bugs. Thus protracted copulations have a clear cost in rates of movement and possibly risks of predation, but there are no apparent mobility costs for egg carrying.  相似文献   

7.
The purpose of this article is to investigate temporal shifts in skeletal robusticity to infer behavioral changes in two populations (Neolithic, NEOL and Medieval, MED) settled in the same geographic area but involved in different subsistence economies (pastoralism and coastal resources exploitation). This comparison allows us to test the hypothesis that occupational stress and mobility in the same environment produce predictable changes in the robusticity of both upper and lower limbs. Results show a lower degree of humeral robusticity and a similar degree of humeral asymmetry in the two sexes in the MED population. These results are consistent with the relatively less stressful subsistence economy documented in the MED population relative to that of the NEOL. Lower limb results suggest that femoral robusticity does not correlate directly with the level of logistical mobility, but is instead due to the summation of several diverse factors that place biomechanical loads on the hindlimb, particularly unevenness of the terrain. However, female femoral gracility seems to indicate that below a certain "threshold" of mobility, i.e., movement over the natural terrain, terrain conformation is no longer the main contributing factor to femoral robusticity. The femoral shape index I(x)/I(y) declines through time, particularly in males. This agrees with the expected mobility of the samples based on archaeological and historical data, providing further evidence on the reliability of this index in inferring terrestrial mobility.  相似文献   

8.
In a field study of the grain aphid Sitobion avenae (F.) almost all apterous aphids were found to move from the natal ear before reproducing, and alatiform nymphs usually moved between ears during their development. Apterae were very mobile, with over 50% staying on one ear for less than 24 h. Movements did not appear to be a response to climatic conditions, predation or colony density.
Résumé Lors de l'étude de Sitobion avenae dans la nature, on a constaté que presque tous les individus aptères avaient quitté leur épi d'origine avant la reproduction, et que les larves de type ailé s'étaient déplacées généralement entre les épis pendant leur développement. Les aptères étaient très mobiles, la majorité restant moins de 24 h sur le même épi. Ces déplacements n'ont pas semblé dépendre des conditions climatiques, de la prédation ou de la densité des colonies.
  相似文献   

9.
This review of Natasha Warikoo’s timely and insightful intervention on the relationship between race, social mobility and elite university institutions argues that education has always presented a profoundly contested terrain for debates about race, racism and inclusion but that for too long those debates were confined to pre-eighteen education. The review argues that this study, with its revelatory, comparative U.S./U.K. lens, reveals the complex tensions, ambitions, achievements, identifications, anxieties, limits of diversity, and denials that shape the experiences and perspectives of those students who are part of the population of elite universities. It concludes that Warikoo’s work makes an original and important contribution to the emergent and much needed sociology of higher education.  相似文献   

10.
The experiments were conducted with Cucumis sativus L., Triticum aestivum L., Brassica capitata, Solanum tuberosum, Zea mays L. and Pisum sativum L. Temperature drop increased cold resistance in all studied species. Level of cold resistance under the drop treatments was much higher than under the constant low temperature. It remained at a higher level for a longer period during de-acclimation. It is concluded that DROP technology is a good way for successful transplantation of greenhouse agricultural and bedding plants in early spring.  相似文献   

11.
In parentage assignment by exclusion, using multiple and very polymorphic loci, genotyping errors are a major cause of non‐assignment. Using stochastic simulations, we tested the possibility to allow for mismatches at one or more allele as a way to recover assignment power. This was very efficient provided the set of loci used had a high assignment power (> 99%) and the error rate was not too high (below 3–4%). In these cases, most of the theoretical assignment power could be recovered. We also showed the efficiency of the method in a practical experiment with rainbow trout.  相似文献   

12.
Water beetles are proficient drag-powered swimmers,with oar-like legs.Inspired by this mechamsm,here we propose a miniature robot,with mobility provided by a pair of legs with swimming appendages.The robot has optimized linkage structure to maximize the stroke angle,which is actuated by a single DC motor with a series of gears and a spring.A simplified swimming appendage model is proposed to calculate the deflection due to the applied drag force,and is compared with simulated data using COMSOL Multiphysics.Also,the swimming appendages are optimized by considering their locations on the legs using two fitness functions,and six different configurations are selected.We investigate the performance of the robot with various types of appendage using a high-speed camera,and motion capture cameras.The robot with the proposed configuration exhibits fast and efficient movement compared with other robots.In addition,the locomotion of the robot is analyzed by considering its dynamics,and compared with that of a water boatman (Corixidae).  相似文献   

13.
14.
15.
Cdc42 plays important roles in cytoskeleton organization, cell cycle progression, signal transduction, and vesicle trafficking. Overactive Cdc42 has been implicated in the pathology of cancers, immune diseases, and neuronal disorders. Therefore, Cdc42 inhibitors would be useful in probing molecular pathways and could have therapeutic potential. Previous inhibitors have lacked selectivity and trended toward toxicity. We report here the characterization of a Cdc42-selective guanine nucleotide binding lead inhibitor that was identified by high throughput screening. A second active analog was identified via structure-activity relationship studies. The compounds demonstrated excellent selectivity with no inhibition toward Rho and Rac in the same GTPase family. Biochemical characterization showed that the compounds act as noncompetitive allosteric inhibitors. When tested in cellular assays, the lead compound inhibited Cdc42-related filopodia formation and cell migration. The lead compound was also used to clarify the involvement of Cdc42 in the Sin Nombre virus internalization and the signaling pathway of integrin VLA-4. Together, these data present the characterization of a novel Cdc42-selective allosteric inhibitor and a related analog, the use of which will facilitate drug development targeting Cdc42-related diseases and molecular pathway studies that involve GTPases.  相似文献   

16.
17.
Theoretical studies have predicted that reproductive interference must exclude either of the interacting species, but no testing of this prediction has ever been reported for natural populations. This study surveyed the distribution patterns of herbaceous Veronica plants, including one native and three alien species, to test whether the invasion of the alien species exerting reproductive interference excluded the native species. Results showed that the native species was repeatedly excluded from islands where an alien species invaded, exerting reproductive interference, and that other alien species had no significant effect on the native population survival. This survey also demonstrated that the native species altered its habitat from the ground to stone walls on the mainland where the alien species had been predominant. In the mainland populations, the fruit morphology differed from that of the islands, and the morphology in the mainland population seemed suitable for seed dispersion by ants at a stone wall habitat. We also surveyed the genetic differentiation among populations, the results of which did not support the native species genetically differentiated between mainland and island populations before the alien species invasion. These results strongly suggest that the reproductive interference excluded the recipient species at the population level and facilitated the habitat change. Additionally, results indicated that a series of field surveys of islands close to the mainland can be a powerful tool to test the ecological importance of reproductive interference.  相似文献   

18.
Actin is a key structural protein that makes up the cytoskeleton of cells, and plays a role in functions such as division, migration, and vesicle trafficking. It comprises six different cell-type specific isoforms: ACTA1, ACTA2, ACTB, ACTC1, ACTG1, and ACTG2. Abnormal actin isoform expression has been reported in many cancers, which led us to hypothesize that it may serve as an early biomarker of cancer. We show an overview of the different actin isoforms and highlight mechanisms by which they may contribute to tumorigenicity. Furthermore, we suggest how the aberrant expression of actin subunits can confer cells with greater proliferation ability, increased migratory capability, and chemoresistance through incorporation into the normal cellular F-actin network and altered actin binding protein interaction. Studying this fundamental change that takes place within cancer cells can further our understanding of neoplastic transformation in multiple tissue types, which can ultimately aid in the early-detection, diagnosis and treatment of cancer.  相似文献   

19.
The nucleolus is considered to be a stress sensor and rDNA-based regulation of cellular senescence and longevity has been proposed. However, the role of rDNA in the maintenance of genome integrity has not been investigated in detail. Using genomically diverse industrial yeasts as a model and array-based comparative genomic hybridization (aCGH), we show that chromosome level may be balanced during passages and as a response to alcohol stress that may be associated with changes in rDNA pools. Generation- and ethanol-mediated changes in genes responsible for protein and DNA/RNA metabolism were revealed using next-generation sequencing. Links between redox homeostasis, DNA stability, and telomere and nucleolus states were also established. These results suggest that yeast genome is dynamic and chromosome homeostasis may be controlled by rDNA.  相似文献   

20.
《Cell Stem Cell》2022,29(7):1067-1082.e18
  1. Download : Download high-res image (259KB)
  2. Download : Download full-size image
  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号