走在坎坷的路上

<正>尕考说:除非政府强行要我们单户放牧,否则绝对不分,这是出于对整体的考虑。关于联户的话题,在曲合尔一队的冬窝子里再次展开了。曲合尔一队位于玛曲县西北部,属于欧拉乡,既临着黄河,又靠着阿尼玛卿山,与青海交界,算是黄河拐完了大U形弯后最后即将流出甘肃境内的部分。草场也涵盖了从河滩到山地等各种类型。     

Green revolution: the way forward

The origin of agriculture led to the domestication of many plant species and to the exploitation of natural resources. It took almost 10,000 years for food grain production to reach 1 billion tons, in 1960, and only 40 years to reach 2 billion tons, in 2000. This unprecedented increase, which has been named the 'green revolution', resulted from the creation of genetically improved crop varieties, combined with the application of improved agronomic practices.     

Chemotaxis: signalling the way forward

During random locomotion, human neutrophils and Dictyostelium discoideum amoebae repeatedly extend and retract cytoplasmic processes. During directed cell migration--chemotaxis--these pseudopodia form predominantly at the leading edge in response to the local accumulation of certain signalling molecules. Concurrent changes in actin and myosin enable the cell to move towards the stimulus. Recent studies are beginning to identify an intricate network of signalling molecules that mediate these processes, and how these molecules become localized in the cell is now becoming clear.     

Wild pedigrees: the way forward

Metrics derived from pedigrees are key to investigating several major issues in evolutionary biology, including the quantitative genetic architecture of traits, inbreeding depression, and the evolution of cooperation and inbreeding avoidance. There is merit in studying these issues in natural populations experiencing spatially and temporally variable environmental conditions, since these analyses may yield different results from laboratory studies and allow us to understand population responses to rapid environmental change. Partial pedigrees are now available for several natural populations which are the subject of long-term individual-based studies, and analyses using these pedigrees are leading to important insights. Accurate pedigree construction supported by molecular genetic data is now feasible across a wide range of taxa, and even where only imprecise pedigrees are available it is possible to estimate the consequences of imprecision for the questions of interest. In outbred diploid populations, the pedigree approach is superior to analyses based on marker-based pairwise estimators of coancestry.     

Lipids in exosomes: Current knowledge and the way forward

Lipids are essential components of exosomal membranes, and it is well-known that specific lipids are enriched in exosomes compared to their parent cells. In this review we discuss current knowledge about the lipid composition of exosomes. We compare published data for different lipid classes in exosomes, and what is known about their lipid species, i.e. lipid molecules with different fatty acyl groups. Moreover, we elaborate on the hypothesis about hand-shaking between the very-long-chain sphingolipids in the outer leaflet and PS 18:0/18:1 in the inner leaflet, and we propose this to be an important mechanism in membrane biology, not only for exosomes. The similarity between the lipid composition of exosomes, HIV particles, and detergent resistant membranes, used as lipid rafts models, is also discussed. Furthermore, we summarize knowledge about the role of specific lipids and lipid metabolizing enzymes on the formation and release of exosomes. Finally, the use of exosomal lipids as biomarkers and how the lipid composition of exosomes may be of importance for researchers aiming to use exosomes as drug delivery vehicles is discussed. In conclusion, we have summarized what is presently known about lipids in exosomes and identified issues that should be taken into consideration in future studies.     

ecopa: a powerful concept in the way forward for alternative methods

ecopa, the European Consensus-Platform on Alternatives, is an international not-for-profit organisation, based in Belgium and complying with Belgium Law. It is the only quadripartite organisation that promotes the Three Rs at the European level. Ecopa brings together national consensus platforms on alternative methods. Consensus means that all parties concerned are represented, including animal welfare, industry, academia and government. Ecopa currently includes the National Platforms of 14 EU Member State (or future Member State; eight full members, namely, Austria, Belgium, Finland, Germany, The Netherlands, Spain, Switzerland and the UK, and six associate members, being the Czech Republic, Denmark, Italy, Norway, Poland and Sweden). Ecopa also has three working groups, concerned with: a) the 6th Framework Programme of the EC for Research, Technological Development and Demonstration Activities; b) the EC White Paper Strategy for a Future EU Chemicals Policy; and c) the formation of educational programmes on alternative methods within the EU. Ecopa is thus uniquely placed and has huge expertise to offer to the debate around political topics, including the White Paper, the 6th Framework Programme, and the 7th Amendment of the EU Cosmetics Directive. Ecopa should be considered a key stakeholder by the European Commission and Parliament, and it is essential that the views of ecopa are fully incorporated into future legislation. Recently, the ecopa working groups made a strong common statement on the Chemicals Policy White Paper and made a number of recommendations to the Commission based on scientific, practical and realistic grounds. These are to be found on the ecopa Web site (http://www.ecopa.tsx.org/).     

Unpacking the species conundrum: philosophy,practice and a way forward

The history of ecology and evolutionary biology is rife with attempts to define and delimit species. However, there has been confusion between concepts and criteria, which has led to discussion, debate, and conflict, eventually leading to lack of consistency in delimitation. Here, we provide a broad review of species concepts, a clarification of category versus concept, an account of the general lineage concept (GLC), and finally a way forward for species discovery and delimitation. Historically, species were considered as varieties bound together by reproduction. After over 200 years of uncertainty, Mayr attempted to bring coherence to the definition of species through the biological species concept (BSC). This has, however, received much criticism, and the last half century has spawned at least 20 other concepts. A central philosophical problem is that concepts treat species as ‘individuals’ while the criteria for categorization treats them as ‘classes’. While not getting away from this problem entirely, the GLC attempts to provide a framework where lineage divergence is influenced by a number of different factors (and correlated to different traits) which relate to the different species concepts. We also introduce an ‘inclusive’ probabilistic approach for understanding and delimiting species. Finally, we provide a Wallacean (geography related) approach to the Linnaean problem of identifying and delimiting species, particularly for cases of allopatric divergence, and map this to the GLC. Going one step further, we take a morphometric terrain approach to visualizing and understanding differences between lineages. In summary, we argue that while generalized frameworks may work well for concepts of what species are, plurality and ‘inclusive’ probabilistic approaches may work best for delimitation.     

The contemporary refugee crisis: an overview of mental health challenges

There has been an unprecedented upsurge in the number of refugees worldwide, the majority being located in low‐income countries with limited resources in mental health care. This paper considers contemporary issues in the refugee mental health field, including developments in research, conceptual models, social and psychological interventions, and policy. Prevalence data yielded by cross‐sectional epidemiological studies do not allow a clear distinction to be made between situational forms of distress and frank mental disorder, a shortcoming that may be addressed by longitudinal studies. An evolving ecological model of research focuses on the dynamic inter‐relationship of past traumatic experiences, ongoing daily stressors and the background disruptions of core psychosocial systems, the scope extending beyond the individual to the conjugal couple and the family. Although brief, structured psychotherapies administered by lay counsellors have been shown to be effective in the short term for a range of traumatic stress responses, questions remain whether these interventions can be sustained in low‐resource settings and whether they meet the needs of complex cases. In the ideal circumstance, a comprehensive array of programs should be provided, including social and psychotherapeutic interventions, generic mental health services, rehabilitation, and special programs for vulnerable groups. Sustainability of services, ensuring best practice, evidence‐based approaches, and promoting equity of access must remain the goals of future developments, a daunting challenge given that most refugees reside in settings where skills and resources in mental health care are in shortest supply.