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1.
Mirror neurons are a specific type of visuomotor neuron that discharge both when a monkey executes a motor act and when it observes a similar motor act performed by another individual. In this article, we review first the basic properties of these neurons. We then describe visual features recently investigated which indicate that, besides encoding the goal of motor acts, mirror neurons are modulated by location in space of the observed motor acts, by the perspective from which the others’ motor acts are seen, and by the value associated with the object on which others’ motor acts are performed. In the last part of this article, we discuss the role of the mirror mechanism in planning actions and in understanding the intention underlying the others’ motor acts. We also review some human studies suggesting that motor intention in humans may rely, as in the monkey, on the mirror mechanism.  相似文献   

2.
Vertebrate evolution: recent perspectives from fish   总被引:9,自引:0,他引:9  
Recent progress in understanding the evolution of vertebrate genomes has been rapid, and previous notions that all such genomes could be regarded as equivalent in their gene content have been rendered outdated. This notion, often embodied in the representation that vertebrates possess four Hox complexes, still appears in contemporary textbooks of developmental biology. Recent data from the genomes of teleost fish show that this assumption is untrue and suggest that interesting situations might arise from the apparent proliferation of genes among fish.  相似文献   

3.
Superovulation protocols have evolved greatly over the past 40 to 50 years. The development of commercial pituitary extracts and prostaglandins in the 1970s, and partially purified pituitary extracts and progesterone-releasing devices in the 1980s and 1990s have provided for the development of many of the protocols that we use today. Furthermore, the knowledge of follicular wave dynamics through the use of real-time ultrasonography and the development of the means by which follicular wave emergence can be controlled have provided new practical approaches. Although some embryo transfer practitioners still initiate superstimulatory treatments during mid-cycle in donor cows, the elective control of follicular wave emergence and ovulation has had a great effect on the application of on-farm embryo transfer, especially when large groups of donors need to be superstimulated at the same time. The most common treatment for the synchronization of follicular wave emergence for many years has been estradiol and progestins. In countries where estradiol cannot be used, practitioners have turned to alternative treatments for the synchronization of follicle wave emergence, such as mechanical follicle ablation or the administration of GnRH to induce ovulation. An approach that has shown promise is to initiate FSH treatments at the time of the emergence of the new follicular wave after GnRH-induced ovulation of an induced persistent follicle. Alternatively, it has been suggested recently that it might be possible to ignore follicular wave status, and by extending the treatment protocol, induce small antral follicles to grow and superovulate. Recently, the mixing of FSH with sustained release polymers or the development of long-acting recombinant FSH products have permitted superstimulation with a single or alternatively, two gonadotropin treatments 48 hours apart, reducing the need for animal handling during superstimulation. Although the number of transferable embryos per donor cow superstimulated has not increased, the protocols that are used today have increased the numbers of transferable embryos recovered per unit time and have facilitated the application of on-farm embryo transfer programs. They are practical, easy to administer by farm personnel, and more importantly, they eliminate the need for detecting estrus.  相似文献   

4.
Aggression and violence are concerns that engage us across society as moral and cultural issues. They are also critical issues for mental health research--both for survivors and for understanding how such behaviors occur. Interpersonal violence often explodes in deliberate acts of physical force leaving survivors behind with a diminished sense of control that is often shadowed by persistent fear and anxiety. The treatment of the victims is a clear and immediate concern; from their perspectives the medical consequences require effective attention whether they suffered as a result of acts of nature, mental disease, ideology, or combinations of these. At the same time preventing violent behavior from happening in the first place is a compelling challenge for public health research.  相似文献   

5.
青钱柳叶是一种古老茶饮,也是国家卫健委认定的新食品原料。青钱柳多糖是其主要活性成分之一,具有降血糖、降血脂、抗氧化、免疫调节等多种功能,在食品、医药和生物医学等领域应用市场潜力巨大。通过综述国内外相关研究文献报道,对青钱柳叶所含功能性多糖的提取工艺、结构特征、药理活性及开发应用的研究现状进行较系统的归纳和分析,并对青钱柳多糖未来研究方向作了展望,拟为开发高活性青钱柳多糖保健食品或药物提供理论依据及研究支撑。  相似文献   

6.
7.
Bacterial resistance to commonly used antibiotics is constantly increasing. Bacteria particularly dangerous for human life are methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecium and fluoroquinolone-resistant Pseudomonas aeruginosa. Hence, there is an incessant need for developing compounds with new modes of action and seeking alternate drug targets. In this review, the authors discuss the current situation of antibacterial medicines and present data on new antibiotic targets. Moreover, alternatives to antibiotics, such as bacteriophages, antimicrobial peptides and monoclonal antibodies, are presented. The authors also draw attention to the valuable features of natural sources in developing antibacterial compounds. The need to prevent and control infections as well as the reasonable use of currently available antibiotics is also emphasized.  相似文献   

8.
All organisms on Earth have evolved biological rhythms to face alternation of periods of favorable and unfavorable environmental conditions, at various temporal scales. Diapause is a state of seasonal dormancy adapted to recurring periods of adverse environmental conditions and triggered by biotic and abiotic factors that precede the arrival of these conditions. Several monographs already review the mechanisms of diapause expression in arthropods, from initiation to termination phases. Rather than adding another review to the literature on this topic, this paper primarily aims to link past concepts on seasonal strategies with new perspective on diapause research in arthropods. By focusing on insects, I examine the legacy of diapause history research in terrestrial arthropods since antiquity but mostly over the past 3 centuries, its contribution to the understanding of insect seasonal ecology, and I explore some of the reasons why it is still relevant to study diapause. I highlight some of the topical issues on which current work focuses to better understand and integrate arthropod diapause with their ecology, especially in the climate change context and for the provision of ecosystem services.  相似文献   

9.
10.
A report on the American Association for Cancer Research Conference 'Advances in Proteomics in Cancer Research', Amelia Island, USA, 27 February-2 March 2007.  相似文献   

11.
Flavonoid glycosides are required for a number of crucial roles in planta and have the potential for development in a variety of agricultural, medicinal, and biotechnological applications. A number of recent advancements have been made in characterizing glycosyltransferases, the enzymes that are responsible for the synthesis of these important molecules. In this review, glycosyltransferases are considered with regard to biochemical properties, expression patterns, levels of enzyme activity during development, and structure/function relationships. This is presented with historical context to highlight critical findings, particularly with regard to the innovative work that has come from research on citrus species. The plant glycosyltransferase crystal structures that have been solved over the past decade, either alone or in complex with sugar donor and/or acceptor molecules, are discussed. The application of results from these structures to inform current structure/function work as well as implications and goals for future crystallography and tertiary modeling studies are considered. A thorough understanding of the properties of glycosyltransferases will be a critical step in any future biotechnological application of these enzymes in areas such as crop improvement and custom design of enzymes to produce desired compounds for nutritional and/or medicinal usage.  相似文献   

12.
Photosynthesis Research - The photosynthetic performance of crop plants under a variety of environmental factors and stress conditions, at the fundamental level, depends largely on the organization...  相似文献   

13.
Yvon Le Maho 《Polar Biology》1994,14(5):315-318
New technology, that is based on miniaturization of electronic equipment and progress in computers, now enables us to get data on the foraging behavior of Antarctic birds and mammals. This technical revolution is of a major scientific importance because until recently it was considered impossible to study where animals feed and how much they consume. Accordingly, feeding strategies may now be studied in relation to breeding status or availability in marine resources. This, in turn, facilitates the use of antarctic animals as indicators of the changes in these resources. Automatic indentification and weighing of breeding seabirds has also become possible. This means changes in their body condition, i.e. body fuel reserves and food stores at sea, can be monitored. Thus a short-term indication of the changes in the availability of some marine resources may now be obtained. These new methods represent a major advance because they open new research possibilities, whereby antarctic animals can be individually monitored or at a population level, ashore and at sea, while minimizing human disturbance.Paper presented at the Symposium on Polar regions: the challenge for biological and ecological research organized by the Swiss Committee for Polar Research, Basel on 2 October 1992  相似文献   

14.
The challenge of discovering new, urgently needed anti-TB drugs from natural sources requires a truly interdisciplinary research. Cutting-edge mycobacteriology and innovative natural products chemistry tools have to be developed and employed in tandem, in order to meet these demands. The present review provides cross-linkage to the most recent literature on anti-TB active natural products and summarizes the recent developments in both fields and their potential to impact the early steps of the TB drug discovery process.  相似文献   

15.
Biotechnical production processes often operate with plasmid-based expression systems in well-established prokaryotic and eukaryotic hosts such as Escherichia coli or Saccharomyces cerevisiae, respectively. Genetically engineered organisms produce important chemicals, biopolymers, biofuels and high-value proteins like insulin. In those bioprocesses plasmids in recombinant hosts have an essential impact on productivity. Plasmid-free cells lead to losses in the entire product recovery and decrease the profitability of the whole process. Use of antibiotics in industrial fermentations is not an applicable option to maintain plasmid stability. Especially in pharmaceutical or GMP-based fermentation processes, deployed antibiotics must be inactivated and removed. Several plasmid addiction systems (PAS) were described in the literature. However, not every system has reached a full applicable state. This review compares most known addiction systems and is focusing on biotechnical applications.  相似文献   

16.
寒武纪大爆发是地球历史上唯一的动物门类创生事件, 导致所有现生动物门类几乎同时在寒武纪早期海洋中首现——地球动物树成型。显生宙之后的其他重大地质事件甚至动植物登陆过程中地球再无新的动物门类出现。因此, 寒武纪大爆发既是重大生命事件也是地质事件, 成为地球宜居性演化研究的关键。国内外许多研究团队和学者从不同的视角对寒武纪大爆发做了深入探索和思考, 取得了系列成果和认识。基于生命物质的组织层次(organismal hierarchical level)及其地质背景, 本文提出了地球早期生命宏演化包括分子水平进化、细胞水平进化和组织水平进化三大宏演化阶段。据此, 认为寒武纪大爆发的实质是原生生物细胞群“组织化”的必然结果, 并提出寒武纪动物大爆发组织“拼图”新假说(Lego Blocks Hypothesis)。寒武纪动物大爆发的突发性和爆发性是在现代板块构造体制建立和异养型消费者生态位空缺的背景下, 在全球圈层联动、全球海洋微生物和化学循环的促使下, 部分真核细胞发生“分化和特化”形成原始组织后, 快速“拼图组装”的必然结果。期间, 地球海洋生态空间(生态位)多样性剧增、动物消费者生态位空缺及其导致的古地理和生殖隔离, 成为寒武纪早期动物门类爆发的生态动力和生物发育内在需求。罗迪尼亚超大陆裂解和冈瓦纳大陆形成过程中, 全板块深俯冲为标志的现代板块构造体制的建立, 导致全球圈层联动和全球海洋微生物化学循环, 进一步加速了动物门类的生态扩张。显生宙盘古大陆演化和原、古、新特提斯洋发育过程中全球海洋生态空间多样性阈值的稳定甚至减少, 可能成为寒武纪大爆发后地球海洋再无新的动物门类出现的环境条件和地质背景制约。  相似文献   

17.
Behavioral sensitization of psychostimulants was accompanied by alterations in a variety of biochemical molecules in different brain regions. However, which change is actually related to drug-produced sensitization lacks of accurate clarification. In this study, we investigated the role of integrin-linked kinase (ILK) in both the induction and expression of cocaine sensitization. Conditional inhibition of ILK expression was established in the nucleus accumbens (NAc) core by microinjecting recombinant adeno-associated virus-carrying, tetracycline-on-regulated small interfering RNA which reversed the chronic cocaine-induced psychomotor sensitization, as well as the changes in protein kinase B Ser473 phosphorylation, dendritic density, and dendritic spine numbers locally. Importantly, the reversed psychomotor sensitization did not recover after cessation of the silencing for 8 days. We also demonstrated that inhibition of ILK expression pre- and during-chronic cocaine treatments blocked the induction of cocaine psychomotor sensitization and abolished the stimulant effect of cocaine on ILK expression. In contrast, inhibition of ILK expression in the NAc core has no significant effect on cocaine-induced stereotypical behaviors. This concludes that ILK is involved in cocaine sensitization with the earlier induction and later expression functioning as a kinase to regulate protein kinase B Ser473 phosphorylation and a scaffolding protein to regulate the reorganization of the NAc spine morphology.  相似文献   

18.
Immunotherapy of cancer has long been considered as an attractive therapeutic approach but with no impact on clinical practice. Two clinical protocols of immunotherapy, one based on a cancer vaccine in patients with prostate cancer or melanoma and the other using an immunomodulator targeting T cells (anti-CTLA4 mAb) in melanoma patients, have demonstrated clinical efficacy in two phase?III clinical trials. To improve these encouraging clinical results, biomarkers to better select patients which may benefit from this therapy are actively searched. In addition, immunosuppression associated with cancer has to be overcome to allow a better immunostimulation. In contrast to chemotherapy, clinical variables to monitor the efficacy of immunotherapy has to be revisited and overall survival appears to be a better endpoint than clinical response defined by the RECIST criteria. Combination of immunotherapy with conventional treatments (chemotherapy, anti-angiogenic, etc.) should further improve this approach both in its effectiveness and in its clinical indications.  相似文献   

19.
20.
Hedgehog signal transduction: recent findings   总被引:21,自引:0,他引:21  
The Hedgehog (Hh) family of signaling molecules are key agents in patterning numerous types of tissues. Mutations in Hh and its downstream signaling molecules are also associated with numerous oncogenic and disease states. Consequently, understanding the mechanisms by which Hh signals are transduced is important for understanding both development and disease. Recent studies have clarified several aspects of Hh signal transduction. Several new Sonic Hedgehog binding partners have been identified. Cholesterol and palmitic acid modifications of Hh and Sonic hedgehog have been examined in greater detail. Characterization of the trafficking patterns of the Patched and Smoothened proteins has demonstrated that these two proteins function very differently from the previously established models. The Fused kinase has been demonstrated to phosphorylate the kinesin-like protein Costal2 and the sites identified, while Cubitus interruptus has been shown to be phosphorylated in a hierarchical manner by three different kinases. Finally, the interactions, both genetic and physical, between Fused, Costal2, Cubitus interruptus, and Suppressor of Fused have been further elucidated.  相似文献   

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