Geographic structure and dynamics of coevolutionary selection

Coevolution of species is one of the major processes organizing the Earth's biodiversity. Recent coevolutionary theory has indicated that the geographic structure of species has the potential to impose powerful and continuing effects on coevolutionary dynamics, if that structure creates selection mosaics and coevolutionary hotspots across landscapes. Here we confirm that current coevolutionary selection in interspecific interactions can be highly divergent across both narrow and broad geographic scales, thereby fueling continuing coevolution of taxa. Study of a widespread plant insect interaction across a broad range of habitats for several years showed that an insect functioning both as a pollinator and a floral parasite can be strongly mutualistic in some habitats but commensal or antagonistic in neighbouring habitats. The results for one of the habitats span seven years, demonstrating that the local structure of coevolutionary selection can remain stable across multiple generations. Conservation of the evolutionary processes maintaining long-term biological diversity may require preservation of the conditions that allow a long-term shifting geographic mosaic of coevolutionary hotspots and coldspots.     

Biological pacemaker created by gene transfer

The pacemaker cells of the heart initiate the heartbeat, sustain the circulation, and dictate the rate and rhythm of cardiac contraction. Circulatory collapse ensues when these specialized cells are damaged by disease, a situation that currently necessitates the implantation of an electronic pacemaker. Here we report the use of viral gene transfer to convert quiescent heart-muscle cells into pacemaker cells, and the successful generation of spontaneous, rhythmic electrical activity in the ventricle in vivo. Our results indicate that genetically engineered pacemakers could be developed as a possible alternative to implantable electronic devices.     

卤素离子在多晶铜电极表面的微分电容研究

本文通过测量金属晶体电极表面的微分电容研究了金属电极表面在金属与水溶液界面上的吸附能力,以及金属与吸附质之间的相互作用。文中论述了多晶铜电极在(0.5-x)mNaClO_4+xmNaBr的一系列不同x值的溶液中的微分电容测量值及微分电容-电位曲线,证明了F~-和ClO_4~-离子在多晶铜电极表面是非常弱的吸附,Br~-离子在多晶铜电极表面具有特定的吸附,每条电容-电位曲线有一个凸起的峰。在峰所对应的位能值,金属表面对阴离子的吸附能力强,证实金属-吸附质之间的相互作用强,吸附的阴离子在过渡层中散射导电电子的能力也强。对于相同阴离子和金属的体系,其微分电容与吸附质的浓度、电压、溶液的pH值和表面的非均匀性等因素密切有关。研究证明,金属晶体电极表面在电解质溶液中的微分电容的变化规律类似于表面电反射信号的强弱变化规律,微分电容大小取决于金属-吸附质之间的电荷转移程度。     

The European dimension for the mouse genome mutagenesis program

The European Mouse Mutagenesis Consortium is the European initiative contributing to the international effort on functional annotation of the mouse genome. Its objectives are to establish and integrate mutagenesis platforms, gene expression resources, phenotyping units, storage and distribution centers and bioinformatics resources. The combined efforts will accelerate our understanding of gene function and of human health and disease.     

Mutagenic insertion and chromosome engineering resource (MICER)

Embryonic stem cell technology revolutionized biology by providing a means to assess mammalian gene function in vivo. Although it is now routine to generate mice from embryonic stem cells, one of the principal methods used to create mutations, gene targeting, is a cumbersome process. Here we describe the indexing of 93,960 ready-made insertional targeting vectors from two libraries. 5,925 of these vectors can be used directly to inactivate genes with an average targeting efficiency of 28%. Combinations of vectors from the two libraries can be used to disrupt both alleles of a gene or engineer larger genomic changes such as deletions, duplications, translocations or inversions. These indexed vectors constitute a public resource (Mutagenic Insertion and Chromosome Engineering Resource; MICER) for high-throughput, targeted manipulation of the mouse genome.     

Chemical properties of alcohols and their protein binding sites

Alcohols affect a wide array of biological processes including protein folding, neurotransmission and immune responses. It is becoming clear that many of these effects are mediated by direct binding to proteins such as neurotransmitter receptors and signaling molecules. This review summarizes the unique chemical properties of alcohols which contribute to their biological effects. It is concluded that alcohols act mainly as hydrogen bond donors whose binding to the polypeptide chain is stabilized by hydrophobic interactions. The electronegativity of the O atom may also play a role in stabilizing contacts with the protein. Properties of alcohol binding sites have been derived from X-ray crystal structures of alcohol-protein complexes and from mutagenesis studies of ion channels and enzymes that bind alcohols. Common amino acid sequences and structural features are shared among the protein segments that are involved in alcohol binding. The alcohol binding site is thought to consist of a hydrogen bond acceptor in a turn or loop region that is often situated at the N-terminal end of an alpha-helix. The methylene chain of the alcohol molecule appears to be accommodated by a hydrophobic groove formed by two or more structural elements, frequently a turn and an alpha-helix. Binding at these sites may alter the local protein structure or displace bound solvent molecules and perturb the function of key proteins.     

Evolution of genes and genomes on the Drosophila phylogeny

Comparative analysis of multiple genomes in a phylogenetic framework dramatically improves the precision and sensitivity of evolutionary inference, producing more robust results than single-genome analyses can provide. The genomes of 12 Drosophila species, ten of which are presented here for the first time (sechellia, simulans, yakuba, erecta, ananassae, persimilis, willistoni, mojavensis, virilis and grimshawi), illustrate how rates and patterns of sequence divergence across taxa can illuminate evolutionary processes on a genomic scale. These genome sequences augment the formidable genetic tools that have made Drosophila melanogaster a pre-eminent model for animal genetics, and will further catalyse fundamental research on mechanisms of development, cell biology, genetics, disease, neurobiology, behaviour, physiology and evolution. Despite remarkable similarities among these Drosophila species, we identified many putatively non-neutral changes in protein-coding genes, non-coding RNA genes, and cis-regulatory regions. These may prove to underlie differences in the ecology and behaviour of these diverse species.