Trypanosoma cruzi: Immunoperoxidase antibody test for serologic diagnosis

An indirect antiglobulin immunoperoxidase test was developed for the serological diagnosis of American Trypanosomiasis. Purified rabbit antihuman IgG was labeled with the enzyme and the conjugate so obtained was characterized according to its immune and enzymatic activities, with the help of such parameters as the authors have recently described. For a maximal sensitivity in the tests, high antibody levels and a high-labeling ratio were chosen, as well as dilutions of conjugate ensuring maximal reactivity. Positive tests were found in all 90 serum samples from patients with Chagas' disease and titers did not differ significantly from those observed in immunofluorescence tests done in parallel. The specificity of both tests was also similar, as indicated by the results found for serum samples from 60 patients with other diseases, parasitic or not, showing high levels of antibodies against other infective agents or autoantibodies, and in 15 normals.     

北京永定河-海河干流河岸带植物的区系分析

探讨了北京永定河-海河干流河岸带植物区系特征。结果表明,河岸带植被中共有维管束植物37科100属134种,其中包括种子植物36科100属133种,蕨类植物1科1种。北京永定河-海河干流河岸带植物种类比较丰富,其中,在科的组成结构上,植物种类主要集中于少数几个大科如为禾本科和菊科,而多数科只有少数种或单种。在属的组成结构上,主要以单种属和小属为主。对其中种子植物的植物区系分布类型在种级水平上进行了分析,结果表明:河岸带共有4大类区系性质成分和16个地理成分类型,总体呈温带特性,各类温带分布类型67种,占河岸带植物总种数的50%。各河段河岸带植物区系结构存在差异:永定河山峡段与海河干流段区系结构比较相近,各结构在植物种所占比例上的排序为温带类世界类热带类亚洲类;而大部分长期干涸的永定河平原段,则温带类热带类世界类亚洲类。     

Genome‐wide association study identifies loci associated with liability to alcohol and drug dependence that is associated with variability in reward‐related ventral striatum activity in African‐ and European‐Americans

Genetic influences on alcohol and drug dependence partially overlap, however, specific loci underlying this overlap remain unclear. We conducted a genome‐wide association study (GWAS) of a phenotype representing alcohol or illicit drug dependence (ANYDEP) among 7291 European‐Americans (EA; 2927 cases) and 3132 African‐Americans (AA: 1315 cases) participating in the family‐based Collaborative Study on the Genetics of Alcoholism. ANYDEP was heritable (h ² in EA = 0.60, AA = 0.37). The AA GWAS identified three regions with genome‐wide significant (GWS; P < 5E‐08) single nucleotide polymorphisms (SNPs) on chromosomes 3 (rs34066662, rs58801820) and 13 (rs75168521, rs78886294), and an insertion‐deletion on chromosome 5 (chr5:141988181). No polymorphisms reached GWS in the EA. One GWS region (chromosome 1: rs1890881) emerged from a trans‐ancestral meta‐analysis (EA + AA) of ANYDEP, and was attributable to alcohol dependence in both samples. Four genes (AA: CRKL, DZIP3, SBK3; EA: P2RX6) and four sets of genes were significantly enriched within biological pathways for hemostasis and signal transduction. GWS signals did not replicate in two independent samples but there was weak evidence for association between rs1890881 and alcohol intake in the UK Biobank. Among 118 AA and 481 EA individuals from the Duke Neurogenetics Study, rs75168521 and rs1890881 genotypes were associated with variability in reward‐related ventral striatum activation. This study identified novel loci for substance dependence and provides preliminary evidence that these variants are also associated with individual differences in neural reward reactivity. Gene discovery efforts in non‐European samples with distinct patterns of substance use may lead to the identification of novel ancestry‐specific genetic markers of risk.     

Site-directed chemically-modified magnetic enzymes: fabrication,improvements, biotechnological applications and future prospects

Numerous enzymes of biotechnological importance have been immobilized on magnetic nanoparticles (MNP) via random multipoint attachment, resulting in a heterogeneous protein population with potential reduction in activity due to restriction of substrate access to the active site. Several chemistries are now available, where the modifier can be linked to a single specific amino acid in a protein molecule away from the active-site, thus enabling free access of the substrate. However, rarely these site-selective approaches have been applied to immobilize enzymes on nanoparticles. In this review, for the first time, we illustrate how to adapt site-directed chemical modification (SDCM) methods for immobilizing enzymes on iron-based MNP. These strategies are mainly chemical but may additionally require genetic and enzymatic methods. We critically examine each method and evaluate their scope for simple, quick, efficient, mild and economical immobilization of enzymes on MNP. The improvements in the catalytic properties of few available examples of immobilized enzymes are also discussed. We conclude the review with the applications and future prospects of site-selectively modified magnetic enzymes and potential benefits of this technology in improving enzymes, including cold-adapted homologues, modular enzymes, and CO₂-sequestering, as well as non-iron based nanomaterials.     

Nuclear localization of enhanced green fluorescent protein homomultimers

The green fluorescent protein (GFP) and its variants are used in many studies to determine the subcellular localization of other proteins by analyzing fusion proteins. The main problem for nuclear localization studies is the fact that, to some extent, GFP translocates to the nucleus on its own. Because the nuclear import could be due to unspecific diffusion of the relatively small GFP through the nuclear pores, we analyzed the localization of multimers of a GFP variant, the enhanced GFP (EGFP). By detecting the fluorescence of the expressed proteins in gels after nonreducing SDS-PAGE, we demonstrate the integrity of the expressed proteins. Nevertheless, even EGFP homotetramers and homohexamers are found in the nuclei of the five analyzed mammalian cell lines. The use of fusion constructs of small proteins with multimeric EGFP alone, therefore, is not adequate to prove nuclear import processes. Fusion to tetrameric EGFP in combination with a careful quantification of the fluorescence intensities in the nucleus and cytoplasm might be sufficient in many cases to identify a significant difference between the fusion protein and tetrameric EGFP alone to deduce a nuclear localization signal.     

Individualistic responses of bird species to environmental change

We investigated how the population dynamics of the same bird species varied in different environments, and how the population dynamics of different species varied in the same environment, by calculating long-term population trends for 59 insectivorous songbird species in 22 regions or strata of eastern and central North America using data from the North American Breeding Bird Survey. Of the 47 species that occurred in more than one region 77% increased in some regions and declined in others. Of the 22 regions 91% had some species that increased and others that decreased. There were only slightly more significant correlations between strata in species trends and between species for stratum trends than would be expected by chance. Because of nonlinearities in the data, the actual patterns of population fluctuations of the same species in different regions and of different species in the same region were even more heterogeneous than suggested by our analyses of linear trends. We conclude that these bird species respond to spatial and temporal variation in their environment in a very individualistic fashion. These individualistic responses show that the extrapolation of population trends gained from a few local studies to a larger spatial scale, and the use of a few indicator species to monitor the status of a broader community, are suspect.     

Voles on small islands: effects of food limitation and alien predation

Ecosystems of three trophic levels may be bottom-up (by food-plant availability) and/or top-down (by predators) limited. Top-down control might be of greater consequence when the predation impact comes from an alien predator. We conducted a replicated two-factor experiment with field voles (Microtus agrestis) during 2004-2005 on small islands of the outer archipelago of the Baltic Sea, south-west Finland, manipulating both predation impact by introduced American mink (Mustela vison) and winter food supply. In autumn 2004, we live-trapped voles on five islands from which mink had been consistently removed, and on four islands where mink were present, and provided half of these islands with 1.8 kg oats per vole. Body mass of female voles increased as a response to supplementary food, whereas both food supplementation and mink removal increased the body mass of male voles in subsequent spring. During winter, there was a positive effect of supplementary food, but in the subsequent summer, possible positive long-term impacts of food supplementation on field voles were not detected. Mink removal appeared not to affect density estimates of field voles during the winter and summer immediately after food addition. Trapping data from 2004 to 2005 and 2007 suggested, however, that in two out of three summers densities of voles were significantly higher in the absence than in the presence of mink. We conclude that vole populations on small islands in the archipelago of the Baltic Sea are mainly bottom-up limited during winter (outside the growing season of food plants), when food availability is low, and limited by mink predation during summer which slows population growth during the reproductive season of voles.     

The pace of past climate change vs. potential bird distributions and land use in the United States

Climate change may drastically alter patterns of species distributions and richness, but predicting future species patterns in occurrence is challenging. Significant shifts in distributions have already been observed, and understanding these recent changes can improve our understanding of potential future changes. We assessed how past climate change affected potential breeding distributions for landbird species in the conterminous United States. We quantified the bioclimatic velocity of potential breeding distributions, that is, the pace and direction of change for each species’ suitable climate space over the past 60 years. We found that potential breeding distributions for landbirds have shifted substantially with an average velocity of 1.27 km yr^?1, about double the pace of prior distribution shift estimates across terrestrial systems globally (0.61 km yr^?1). The direction of shifts was not uniform. The majority of species’ distributions shifted west, northwest, and north. Multidirectional shifts suggest that changes in climate conditions beyond mean temperature were influencing distributional changes. Indeed, precipitation variables that were proxies for extreme conditions were important variables across all models. There were winners and losers in terms of the area of distributions; many species experienced contractions along west and east distribution edges, and expansions along northern distribution edges. Changes were also reflected in the potential species richness, with some regions potentially gaining species (Midwest, East) and other areas potentially losing species (Southwest). However, the degree to which changes in potential breeding distributions are manifested in actual species richness depends on landcover. Areas that have become increasingly suitable for breeding birds due to changing climate are often those attractive to humans for agriculture and development. This suggests that many areas might have supported more breeding bird species had the landscape not been altered. Our study illustrates that climate change is not only a future threat, but something birds are already experiencing.     

Genetic diversity among isolates of Paenibacillus larvae from Austria

Genetic diversity of 214 Paenibacillus larvae strains from Austria was studied. Genotyping of isolates was performed by polymerase chain reaction (PCR) with primers corresponding to enterobacterial repetitive intergenic consensus (ERIC), BOX repetitive and extragenic palindromic (REP) elements (collectively known as rep-PCR) using ERIC primers, BOX A1R and MBO REP1 primers. Using ERIC-PCR technique two genotypes could be differentiated (ERIC I and II), whereas using combined typing by BOX- and REP-PCR, five different genotypes were detected (ab, aB, Ab, AB and αb). Genotypes aB and αb are new and have not been reported in other studies using the same techniques.     

西洋参有效成分与气候生态因子的关系

通过回归分析、灰色关联分析等方法系统地分析了气候生态因子对西洋参有效成分含量的影响,结果表明：温度和日照是影响西洋参总皂甙含量的主要气候因子;其总皂甙的含量与总氨基酸的含量呈显著负相关,故气候因子对二者的作用方向相反;影响西洋参醚浸出物、醇浸出物以及水溶性浸出物含量的主要气候因子均为气温日较差和日照时。