High-quality male field crickets invest heavily in sexual display but die young

Only high-quality males can bear the costs of an extreme sexual display. As a consequence, such males are not only more attractive, but they often live longer than average. Recent theory predicts, however, that high-quality males should sometimes invest so heavily in sexual displays that they die sooner than lower quality males. We manipulated the phenotypic quality of field crickets, Teleogryllus commodus, by altering the protein content of their diet. Here we show that nymphs and adult females reared on a high-protein diet lived longer than those on a low-protein diet. In contrast, adult males reared on a high-protein diet died sooner than those on low-protein diets because they invested more energy in calling during early adulthood. Our findings uphold the theoretical prediction that the relationship between longevity and sexual advertisement may be dynamic (that is, either positive or negative), depending on local conditions such as resource availability. Moreover, they caution the use of longevity as a proxy for fitness in sexual selection studies, and suggest avenues for future research on the relationship between sexual attractiveness and ageing.     

Comparative analyses of multi-species sequences from targeted genomic regions

The systematic comparison of genomic sequences from different organisms represents a central focus of contemporary genome analysis. Comparative analyses of vertebrate sequences can identify coding and conserved non-coding regions, including regulatory elements, and provide insight into the forces that have rendered modern-day genomes. As a complement to whole-genome sequencing efforts, we are sequencing and comparing targeted genomic regions in multiple, evolutionarily diverse vertebrates. Here we report the generation and analysis of over 12 megabases (Mb) of sequence from 12 species, all derived from the genomic region orthologous to a segment of about 1.8 Mb on human chromosome 7 containing ten genes, including the gene mutated in cystic fibrosis. These sequences show conservation reflecting both functional constraints and the neutral mutational events that shaped this genomic region. In particular, we identify substantial numbers of conserved non-coding segments beyond those previously identified experimentally, most of which are not detectable by pair-wise sequence comparisons alone. Analysis of transposable element insertions highlights the variation in genome dynamics among these species and confirms the placement of rodents as a sister group to the primates.     

Crystal structure of an NK cell immunoglobulin-like receptor in complex with its class I MHC ligand

Target cell lysis is regulated by natural killer (NK) cell receptors that recognize class I MHC molecules. Here we report the crystal structure of the human immunoglobulin-like NK cell receptor KIR2DL2 in complex with its class I ligand HLA-Cw3 and peptide. KIR binds in a nearly orthogonal orientation across the alpha1 and alpha2 helices of Cw3 and directly contacts positions 7 and 8 of the peptide. No significant conformational changes in KIR occur on complex formation. The receptor footprint on HLA overlaps with but is distinct from that of the T-cell receptor. Charge complementarity dominates the KIR/HLA interface and mutations that disrupt interface salt bridges substantially diminish binding. Most contacts in the complex are between KIR and conserved HLA-C residues, but a hydrogen bond between Lys 44 of KIR2DL2 and Asn 80 of Cw3 confers the allotype specificity. KIR contact requires position 8 of the peptide to be a residue smaller than valine. A second KIR/HLA interface produced an ordered receptor-ligand aggregation in the crystal which may resemble receptor clustering during immune synapse formation.     

难解的闪光之谜?

来自遥远宇宙边缘的闪光,可能打碎人类已知关于宇宙运行所想象到的一切清规戒律。本文作者迈克尔·布鲁克斯(Michael Brooks)则对物理学的未来忧心忡忡——     

Genome sequence of Yersinia pestis, the causative agent of plague

The Gram-negative bacterium Yersinia pestis is the causative agent of the systemic invasive infectious disease classically referred to as plague, and has been responsible for three human pandemics: the Justinian plague (sixth to eighth centuries), the Black Death (fourteenth to nineteenth centuries) and modern plague (nineteenth century to the present day). The recent identification of strains resistant to multiple drugs and the potential use of Y. pestis as an agent of biological warfare mean that plague still poses a threat to human health. Here we report the complete genome sequence of Y. pestis strain CO92, consisting of a 4.65-megabase (Mb) chromosome and three plasmids of 96.2 kilobases (kb), 70.3 kb and 9.6 kb. The genome is unusually rich in insertion sequences and displays anomalies in GC base-composition bias, indicating frequent intragenomic recombination. Many genes seem to have been acquired from other bacteria and viruses (including adhesins, secretion systems and insecticidal toxins). The genome contains around 150 pseudogenes, many of which are remnants of a redundant enteropathogenic lifestyle. The evidence of ongoing genome fluidity, expansion and decay suggests Y. pestis is a pathogen that has undergone large-scale genetic flux and provides a unique insight into the ways in which new and highly virulent pathogens evolve.     

中国首次岸基GNSS-R海洋遥感实验

GNSS-Reflection技术是一种崭新的海洋遥感技术. 它利用导航卫星的海面反射信号可获取海浪、潮汐及海面风场等重要信息, 是海洋遥感的前沿领域. 报道了中国岸基GNSS-R海洋遥感实验—— CORE实验, 研究了利用GPS卫星直达波与反射波信号反演海洋参数的方法, 给出了有效波高的最新反演结果, 并利用同步观测进行了对比验证.     

Developing a genome-wide selection model for genetic improvement of residual feed intake and carcass merit in a beef cattle breeding program

Residual feed intake (RFI) and carcass merit (CM) are both complex traits emerging as critical targets for beef genetic improvement.RFI and CM traits are difficult and expensive to measure and genetic improvement for these traits through traditional selection methods is not very effective.Therefore,genome-wide selection using DNA markers may be a potential alternative for genetic improvement of these traits.In this study,the efficiency of a genome-wide selection model for genetic improvement of RFI and CM was assessed.The Illumina Bovine50K bead chip was used to genotype 922 beef cattle from the Kinsella Beef Research Ranch of the University of Alberta.A Bayes model and multiple marker regression using a stepwise method were used to conduct the association test.The number of significant SNP markers for carcass weight (CWT),carcass back fat (BF),carcass rib eye area (REA),carcass grade fat (GDF),lean meat yield (LMY),and residual feed intake (RFI) were 75,54,67,57,44 and 50,respectively.Bi-variate analysis of marker scores and phenotypes for all traits were made using DMU Software.The genetic parameter for each trait was estimated.The genetic correlations of marker score and phenotype for CWT,BF,REA,GDF,LMY and RFI were 0.75,0.69,0.87,0.77,0.78,and 0.85,respectively.The average prediction accuracies of phenotypic EBV for the six traits were increased by 0.05,0.16,0.24,0.23,0.17 and 0.19,respectively.The results of this study indicated that the two-trait marker-assisted evaluation model used was a suitable alternative of genetic evaluation for these traits in beef cattle.     

我们生活在一个五维世界里

我们大家对于四维(空间的三维和时间的一维)是很熟悉的,可是理论家们现在正在重新考虑后加入的第五维,它可能对更清楚地了解宇宙的过去起重要的作用。     

The genome of the simian and human malaria parasite Plasmodium knowlesi

Plasmodium knowlesi is an intracellular malaria parasite whose natural vertebrate host is Macaca fascicularis (the 'kra' monkey); however, it is now increasingly recognized as a significant cause of human malaria, particularly in southeast Asia. Plasmodium knowlesi was the first malaria parasite species in which antigenic variation was demonstrated, and it has a close phylogenetic relationship to Plasmodium vivax, the second most important species of human malaria parasite (reviewed in ref. 4). Despite their relatedness, there are important phenotypic differences between them, such as host blood cell preference, absence of a dormant liver stage or 'hypnozoite' in P. knowlesi, and length of the asexual cycle (reviewed in ref. 4). Here we present an analysis of the P. knowlesi (H strain, Pk1(A+) clone) nuclear genome sequence. This is the first monkey malaria parasite genome to be described, and it provides an opportunity for comparison with the recently completed P. vivax genome and other sequenced Plasmodium genomes. In contrast to other Plasmodium genomes, putative variant antigen families are dispersed throughout the genome and are associated with intrachromosomal telomere repeats. One of these families, the KIRs, contains sequences that collectively match over one-half of the host CD99 extracellular domain, which may represent an unusual form of molecular mimicry.     

凝胶剂中脂溶性茶多酚的含量测定

目的:建立凝胶剂中脂溶性茶多酚的含量测定方法,为制定脂溶性茶多酚凝胶剂质量控制标准提供依据。方法:以无水乙醇为提取溶剂,酒石酸亚铁为显色剂,采用比色法,在540 nm处测定含量。结果:脂溶性茶多酚在0～250 mg.(100 mL)-1浓度范围内线性关系良好(R2=0.9991),平均回收率为102.80%,相对标准偏差为0.93%(n=9)。结论:本法简单、精确、重复性好,可用于凝胶剂中脂溶性茶多酚的含量测定。