外源亚精胺和精胺对NaHCO3胁迫下南蛇藤抗氧化系统的影响

研究了叶面喷施亚精胺和精胺对NaHCO₃胁迫下南蛇藤叶片抗氧化系统的影响.结果表明：外源亚精胺和精胺处理使NaHCO₃胁迫下南蛇藤叶片O₂^-·产生速率、H₂O₂、丙二醛(MDA)含量和电解质外渗率显著降低(P<0.05).亚精胺处理明显提高了盐胁迫下超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)等抗氧化酶的活性,以及还原型谷胱甘肽(GSH)、类胡萝卜素(CAR)和脯氨酸(Pro)等抗氧化剂的含量,但对还原型抗坏血酸(AsA)含量没有作用;精胺处理明显提高NaHCO₃胁迫下POD和APX的活性以及GSH、CAR和Pro的含量,但对SOD和AsA含量影响不显著,甚至引起CAT活性明显降低.亚精胺和精胺处理明显改善了NaHCO₃胁迫下南蛇藤的生长.外源亚精胺和精胺可以改善NaHCO₃胁迫下南蛇藤叶片的膜保护功能,减少叶片中活性氧的积累,从而提高南蛇藤对NaHCO₃胁迫的抗性.     

Artificial intelligence in pest insect monitoring

Abstract Global problems of hunger and malnutrition induced us to introduce a new tool for semi‐automated pest insect identification and monitoring: an artificial neural network system. Multilayer perceptrons, an artificial intelligence method, seem to be efficient for this purpose. We evaluated 101 European economically important thrips (Thysanoptera) species: extrapolation of the verification test data indicated 95% reliability at least for some taxa analysed. Mainly quantitative morphometric characters, such as head, clavus, wing, ovipositor length and width, formed the input variable computation set in a Trajan neural network simulator. The technique may be combined with digital image analysis.     

Antibodies designed as effective cancer vaccines

Antigen/antibody complexes can efficiently target antigen presenting cells to allow stimulation of the cellular immune response. Due to the difficulty of manufacture and their inherent instability complexes have proved inefficient cancer vaccines. However, anti-idiotypic antibodies mimicking antigens have been shown to stimulate both antibody and T cell responses. The latter are due to T cell mimotopes expressed within the complementarity-determining regions (CDRs) of antibodies that are efficiently presented to dendritic cells in vivo. Based on this observation we have designed a DNA vaccine platform called ImmunoBody™, where cytotoxic T lymphocyte (CTL) and helper T cell epitopes replace CDR regions within the framework of a human IgG1 antibody. The ImmunoBody™ expression system has a number of design features which allow for rapid production of a wide range of vaccines. The CDR regions of the heavy and light chain have been engineered to contain unique restriction endonuclease sites, which can be easily opened, and oligonucleotides encoding the T cell epitopes inserted. The variable and constant regions of the ImmunoBody™ are also flanked by restriction sites, which permit easy exchange of other IgG subtypes. Here we show a range of T cell epitopes can be inserted into the ImmunoBody™ vector and upon immunization these T cell epitopes are efficiently processed and presented to stimulate high frequency helper and CTL responses capable of anti-tumor activity.Key words: DNA vaccines, cancer vaccines, melanoma, CTL, helper T cells     

New observations and reinterpretation on the enigmatic taxon Colombitherium (?Pyrotheria,Mammalia) from Colombia

Abstract: The controversial taxon Colombitherium tolimense (Mammalia) (probably Late Eocene in age) from Colombia, although known for nearly 40 years, still bears much mystery. Aside from the problematic ordinal attribution of the holotype and only specimen, its determination as an upper or lower jaw remains a highly debated issue. New observations include the presence of a contact facet on the distal face of the most posterior tooth, which indicates that the fragmentary jaw preserves three premolars and two molars; the M3, unpreserved but present, being most probably reduced. This new interpretation completely fits the morphology of the teeth. Furthermore, the shape of these latter and the deeper wear encompassed by their lingual part relative to the labial one is typical of upper dentition. This is in agreement with the internal curving of the roots of the anterior premolars and with several other arguments that lead interpreting the holotype of C. tolimense as a maxillary bearing P2‐M2. This new interpretation deepens the morphological gap between Colombitherium and other pyrotherians (except Proticia) and challenges further its referral to Pyrotheria. The peculiar morphology of Colombitherium relative to other pyrotherians is indeed striking. In fact, Colombitherium has nothing in common with pyrotherians but bilophodont cheek teeth, a feature largely widespread in placental mammals. It is here referred to ?Pyrotheria until additional evidence of its relationships is known. Associated with the putative removal of Proticia from Pyrotheria as argued by some authors, the hypothetical removal of Colombitherium from the order would adjust the widely accepted assumption that the pyrotherian bilophodont cheek teeth originated from bunodont cheek teeth. It would also make an origin from lophodont forms plausible. This in turn would have critical relevance, especially to the hypothesis that pyrotherians are notoungulates.     

Azygos Vein Lead Implantation For High Defibrillation Thresholds In Implantable Cardioverter Defibrillator Placement

Evaluation of defibrillation threshold is a standard of care during implantation of implantable cardioverter defibrillator. High defibrillation thresholds are often encountered and pose a challenge to electrophysiologists to improve the defibrillation threshold. We describe a case series where defibrillation thresholds were improved after implanting a defibrillation lead in the azygos vein.     

Photosynthetic generation of O2 and H2 by photosystem I-deficient chlamydomonas mutants

A comparative study of aerobic generation of O2 and anaerobic photoproduction of H2 in whole cells of a wild-type strain of Chlamydomonas reinhardtii and its photosystem I-deficient mutants B4 and F8 found no contribution of photosystem II to ferredoxin photoreduction, which is not consistent with data of recent studies by Greenbaum et al. (Nature, 1995, 376, 438-441; and Science, 1996, 273, 364-367) who reported that they had discovered such a capacity in these mutant strains. In the wild-type and mutant strains, action spectra showed that O2 was evolved by photosystem II, whereas photoinhibition of chlororespiration and evolution of H2 depended on the activity of photosystem I. Single-turnover flash measurements of H2 evolution showed that the contents of photosystem I in mutant strains amounted to 3-35% of that in the wild-type strain. This fraction of photosystem I in "leaky" mutants displayed abnormal kinetic features and was highly sensitive to photoinhibition.     

Detection of two loci involved in (1-->3)-beta-glucan (curdlan) biosynthesis by Agrobacterium sp. ATCC31749, and comparative sequence analysis of the putative curdlan synthase gene

Genes essential for the production of a linear, bacterial (1-->3)-beta- glucan, curdlan, have been cloned for the first time from Agrobacterium sp. ATCC31749. The genes occurred in two, nonoverlapping, genomic fragments that complemented different sets of curdlan( crd )-deficient transposon-insertion mutations. These were detected as colonies that failed to stain with aniline blue, a (1-->3)-beta-glucan specific dye. One fragment carried a biosynthetic gene cluster (locus I) containing the putative curdlan synthase gene, crdS, and at least two other crd genes. The second fragment may contain only a single crd gene (locus II). Determination of the DNA sequence adjacent to several locus I mutations revealed homology to known sequences only in the cases of crdS mutations. Complete sequencing of the 1623 bp crdS gene revealed highest similarities between the predicted CrdS protein (540 amino acids) and glycosyl transferases with repetitive action patterns. These include bacterial cellulose synthases (and their homologs), which form (1-->4)-beta-glucans. No similarity was detected with putative (1-->3)- beta-glucan synthases from yeasts and filamentous fungi. Whatever the determinants of the linkage specificity of these beta-glucan synthases might be, these results raise the possibility that (1-->3)-beta-glucans and (1-->4)-beta-glucans are formed by related catalytic polypeptides.      

A state and transition model for the eastern Monte Phytogeographycal Province in Rio Negro

We developed a functional model for a shrub steppe vegetation of the eastern Monte Phytogeographical Province in Río Negro (Argentina) with six stable states and 12 transitions, based on the woody encroachment degree, characteristics of the herbaceous layer and the soil surface, and biological crust cover. Information was obtained from letters of naturalists and travelers along the region since the late eighteenth century, reports of old settlers, and our own research work. On the Monte, different functional groups can be distinguished. Our work focused on the three most conspicuous to analyze the dynamics of the system: shrubs, grasses and biological crust. The shrub layer is only affected by large-scale disturbances (fire, mechanical clearing) which maintain the balance between grasses and shrubs in the system. Mechanical clearing with soil removal also causes a decrease in grass cover and vegetation diversity. This layer, however, is most frequently affected by intensive and continuous grazing, which reduces the occurrence of fires and shifts the equilibrium toward the shrubs. All disturbances in general deteriorate the biological crust that covers the soil, which offers situations of facilitation for the regeneration of the herbaceous layer. Grazing and mechanical clearing reduce soil cover and promote the development of soil compaction, which reduce water infiltration and germination and/or seedling establishment, and this creates deteriorated states difficult to reverse. Those states can also be produced by tillage for agriculture and stubble grazing. Some of the transitions that we describe can be favored through grassland management strategies, in order to reach higher states of pastoral value and reverse deteriorating situations.     

A multi-population phenome-wide association study of genetically-predicted height in the Million Veteran Program

BackgroundHeight has been associated with many clinical traits but whether such associations are causal versus secondary to confounding remains unclear in many cases. To systematically examine this question, we performed a Mendelian Randomization-Phenome-wide association study (MR-PheWAS) using clinical and genetic data from a national healthcare system biobank.Methods and findingsAnalyses were performed using data from the US Veterans Affairs (VA) Million Veteran Program in non-Hispanic White (EA, n = 222,300) and non-Hispanic Black (AA, n = 58,151) adults in the US. We estimated height genetic risk based on 3290 height-associated variants from a recent European-ancestry genome-wide meta-analysis. We compared associations of measured and genetically-predicted height with phenome-wide traits derived from the VA electronic health record, adjusting for age, sex, and genetic principal components. We found 345 clinical traits associated with measured height in EA and an additional 17 in AA. Of these, 127 were associated with genetically-predicted height at phenome-wide significance in EA and 2 in AA. These associations were largely independent from body mass index. We confirmed several previously described MR associations between height and cardiovascular disease traits such as hypertension, hyperlipidemia, coronary heart disease (CHD), and atrial fibrillation, and further uncovered MR associations with venous circulatory disorders and peripheral neuropathy in the presence and absence of diabetes. As a number of traits associated with genetically-predicted height frequently co-occur with CHD, we evaluated effect modification by CHD status of genetically-predicted height associations with risk factors for and complications of CHD. We found modification of effects of MR associations by CHD status for atrial fibrillation/flutter but not for hypertension, hyperlipidemia, or venous circulatory disorders.ConclusionsWe conclude that height may be an unrecognized but biologically plausible risk factor for several common conditions in adults. However, more studies are needed to reliably exclude horizontal pleiotropy as a driving force behind at least some of the MR associations observed in this study.