Biomedicine. New insights into type 2 diabetes

Researchers studying type 2 diabetes are optimistic that they are closing in on the elusive causes of the world's most prevalent metabolic disorder--although no one is willing to bet the bank on it. Using both biochemical and genetic approaches, diabetes researchers have identified multiple intracellular signaling pathways that appear to lie at the heart of this condition, which affects some 250 million people worldwide and is the leading cause of blindness, kidney failure, and amputation among adults. And in the process, they have thrown out much of the dogma of the past 10 years.     

Behavioral neurophysiology: insights into seeing and grasping

One marvels at a batter's ability to hit a baseball traveling at 150 kilometers per hour or a monkey's skill in snatching a flying insect. Indeed, the ability of many animals to reach out, grasp, and manipulate objects is a feat of biological engineering unmatched by even state-of-the-art robots. But how are the objects of our attention chosen and how are the eyes and hands directed to it? Recent progress in behavioral neurophysiology has clarified some of the brain mechanisms at work.     

The Structure of Ordinary Water: New data and interpretations are yielding new insights into this fascinating substance

The train of thought pursued in this article has led to the conclusion that the structure of cold water seems likely to consist, for the most part, of hydrogen-bonded, four-coordinated, framework regions, with interstitial monomers occupying some fraction of the cavities the framework encloses. The precise geometry of the framework has not been specified, but some evidence suggests that it is rather regular at low temperatures and becomes more random as the water gets warmer. These conclusions, meager as they are in comparison with what we shall eventually need to know about water, are still "subject to change without notice." Such a change would, for instance, be made necessary by the discrediting either of the data or of the interpretations on which the model is based. The discovery of new facts, or of new meanings in old facts, which were clearly in conflict with the model, would also make it necessary to modify, if not to abandon, it. Even this would be progress, however, for it would be another product of the method of drawing upon data from diverse sources and would be a further step toward the progressively more comprehensive model to which this method will lead and the progressively greater confidence we will be able to place in our conclusions.     

农业科技传播新思维

根据当前我国农业科技传播体系与机制现状及存在问题,提出了体系与机制创新的思路,强调将农民职业教育作为农业科技传播体系的重要组成部分。     

Protein kinase inhibitors: insights into drug design from structure

Protein kinases are targets for treatment of a number of diseases. This review focuses on kinase inhibitors that are in the clinic or in clinical trials and for which structural information is available. Structures have informed drug design and have illuminated the mechanism of inhibition. We review progress with the receptor tyrosine kinases (growth factor receptors EGFR, VEGFR, and FGFR) and nonreceptor tyrosine kinases (Bcr-Abl), where advances have been made with cancer therapeutic agents such as Herceptin and Gleevec. Among the serine-threonine kinases, p38, Rho-kinase, cyclin-dependent kinases, and Chk1 have been targeted with productive results for inflammation and cancer. Structures have provided insights into targeting the inactive or active form of the kinase, for targeting the global constellation of residues at the ATP site or less conserved additional pockets or single residues, and into targeting noncatalytic domains.     

Genomic insights into the immune system of the sea urchin

Comparative analysis of the sea urchin genome has broad implications for the primitive state of deuterostome host defense and the genetic underpinnings of immunity in vertebrates. The sea urchin has an unprecedented complexity of innate immune recognition receptors relative to other animal species yet characterized. These receptor genes include a vast repertoire of 222 Toll-like receptors, a superfamily of more than 200 NACHT domain-leucine-rich repeat proteins (similar to nucleotide-binding and oligomerization domain (NOD) and NALP proteins of vertebrates), and a large family of scavenger receptor cysteine-rich proteins. More typical numbers of genes encode other immune recognition factors. Homologs of important immune and hematopoietic regulators, many of which have previously been identified only from chordates, as well as genes that are critical in adaptive immunity of jawed vertebrates, also are present. The findings serve to underscore the dynamic utilization of receptors and the complexity of immune recognition that may be basal for deuterostomes and predicts features of the ancestral bilaterian form.     

Structure-based mechanistic insights into DNMT1-mediated maintenance DNA methylation

DNMT1, the major maintenance DNA methyltransferase in animals, helps to regulate gene expression, genome imprinting, and X-chromosome inactivation. We report on the crystal structure of a productive covalent mouse DNMT1(731-1602)-DNA complex containing a central hemimethylated CpG site. The methyl group of methylcytosine is positioned within a shallow hydrophobic concave surface, whereas the cytosine on the target strand is looped out and covalently anchored within the catalytic pocket. The DNA is distorted at the hemimethylated CpG step, with side chains from catalytic and recognition loops inserting through both grooves to fill an intercalation-type cavity associated with a dual base flip-out on partner strands. Structural and biochemical data establish how a combination of active and autoinhibitory mechanisms ensures the high fidelity of DNMT1-mediated maintenance DNA methylation.     

Genome sequence of a polydnavirus: insights into symbiotic virus evolution

Little is known of the fate of viruses involved in long-term obligatory associations with eukaryotes. For example, many species of parasitoid wasps have symbiotic viruses to manipulate host defenses and to allow development of parasitoid larvae. The complete nucleotide sequence of the DNA enclosed in the virus particles injected by a parasitoid wasp revealed a complex organization, resembling a eukaryote genomic region more than a viral genome. Although endocellular symbiont genomes have undergone a dramatic loss of genes, the evolution of symbiotic viruses appears to be characterized by extensive duplication of virulence genes coding for truncated versions of cellular proteins.     

Comparative transcriptome analysis provides insights into the mechanism of pear dwarfing

Dwarfism is an important trait which is closely related to the efficiency of fruit orchard management and production. However, dwarfing cannot be widely applied in the cultivation of pears, especially Asian pears. Developing varieties with dwarf characteristics is a goal of paramount importance in pear breeding. In the present study, dwarf phenotype pears(DPPs) and arborescent phenotype pears(APPs) were obtained from the offspring of a cross between ‘Aiyuxiang’ and ‘Cuiguan’ pear cultivars, whic...     

传播学视角下选择性理论对高校思想政治教育工作的启示

高校思想政治教育工作可以视为一种传播活动,即思想政治教育信息在教育者和大学生之间的传递和接受。将传播学选择性理论研究同高校思想政治教育实践联系起来,探索高校思想政治教育工作新思路和新方法。通过大量的理论研究和实证分析,认为深入有效的了解和沟通、尊重个性差异的因材施教、易得易懂易记的信息传播、妥帖有效的方法技巧,是提高思...     

Atomic structure of PDE4: insights into phosphodiesterase mechanism and specificity

Cyclic nucleotides are second messengers that are essential in vision, muscle contraction, neurotransmission, exocytosis, cell growth, and differentiation. These molecules are degraded by a family of enzymes known as phosphodiesterases, which serve a critical function by regulating the intracellular concentration of cyclic nucleotides. We have determined the three-dimensional structure of the catalytic domain of phosphodiesterase 4B2B to 1.77 angstrom resolution. The active site has been identified and contains a cluster of two metal atoms. The structure suggests the mechanism of action and basis for specificity and will provide a framework for structure-assisted drug design for members of the phosphodiesterase family.