Mechanisms and genetic diversity for host plant resistance to spotted stem borer,Chilo partellus in sorghum,Sorghum bicolor

Levels of resistance to spotted stem borer, Chilo partellus, in the germplasm are low to moderate and therefore we evaluated 25 sorghum genotypes for resistance to stem borer to identify lines with diverse mechanisms of resistance to this insect. Leaf glossiness was significantly and negatively associated with low deadheart formation. Dwarf genotypes with fewer nodes showed more deadheart formation. Antixenosis and/or antibiosis for leaf feeding, and reduced deadheart formation, tunnelling, and number of exit holes resulted in lower losses owing to C. partellus damage. Axillary tillers compensated for loss in grain yield owing to borer infestation as a result of deadheart formation, but their synchrony for maturity with the main plant is quite important. Path coefficient analysis revealed that direct effects of stem tunnelling on loss in grain yield were greater than leaf feeding and deadhearts. However, leaf feeding via stem tunnelling showed maximum indirect effects on loss in grain yield. Estimates for broad‐sense heritability and genetic advance suggested that it is possible to improve for grain yield under stem borer infestation. Heritability estimates for grain yield were usually higher than for stem borer damage parameters. Multi‐trait cluster analysis placed the test genotypes into four and five clusters in rainy and post‐rainy seasons, respectively. The genotypes placed in different groups, and showing resistance to leaf feeding, deadheart formation, stem tunnelling, and/or compensation in grain yield can be used for sorghum improvement.     

欧洲李种子的化学成分研究

利用溶剂萃取和色谱分离手段,从蔷薇科植物欧洲李(Prunus domestica L.)种子中得到6个化合物。通过光谱分析,分别鉴定为松柏醛(1)、东莨菪亭(2)、(-)-二氢脱氢二松柏醇(3)、(-)-榕醛(4)、(E)-3,3’-二甲氧基-4,4’-二羟基茋(5)和5-羟甲基糠醛(6)。这些化合物均系首次从欧洲李种子中分离得到。     

不同减害材料对烟草薄片的减害效果研究

烟草薄片是一种新型的烟草制品,将之回用于卷烟生产过程,既实现了废烟料的综合利用,又提高了卷烟的内在品质。通过采用不同种类的减害材料处理薄片,经过检测分析主流烟气中有害成分含量的变化,筛选出柠檬酸钠、酒石酸钾钠、纳米TiO2-VK-TG01、纳米TiO2-VK-TG02、沸石分子筛这5种合适的材料,作为今后薄片减害的有效添加物。     

WILL POPULATION BOTTLENECKS AND MULTILOCUS EPISTASIS INCREASE ADDITIVE GENETIC VARIANCE?

We apply new analytical methods to understand the consequences of population bottlenecks for expected additive genetic variance. We analyze essentially all models for multilocus epistasis that have been numerically simulated to demonstrate increased additive variance. We conclude that for biologically plausible models, large increases in expected additive variance--attributable to epistasis rather than dominance--are unlikely. Naciri-Graven and Goudet (2003) found that as the number of epistatically interacting loci increases, additive variance tends to be inflated more after a bottleneck. We argue that this result reflects biologically unrealistic aspects of their models. Specifically, as the number of loci increases, higher-order epistatic interactions become increasingly important in these models, with an increasing fraction of the genetic variance becoming nonadditive, contrary to empirical observations. As shown by Barton and Turelli (2004), without dominance, conversion of nonadditive to additive variance depends only on the variance components and not on the number of loci per se. Numerical results indicating that more inbreeding is needed to produce maximal release of additive variance with more loci follow directly from our analytical results, which show that high levels of inbreeding (F > 0.5) are needed for significant conversion of higher-order components. We discuss alternative approaches to modeling multilocus epistasis and understanding its consequences.     

Imaging and speciation of trace elements in biological environment

Mineral elements, often at the trace level, play a considerable role in physiology and pathology of biological systems. Metallogenomics, metalloproteomics, and metallomics are among the emerging disciplines which are critically dependent on spatially resolved concentration maps of trace elements in a cell or tissue, on information on chemical speciation, and on that on metal-binding coordination sites. The mini-review discusses recent progress in analytical techniques for element profiling on the genome scale, biological trace element imaging, and probing, identification and quantification of chemical species in the biological environment. Imaging of the element distribution in cells and tissue sections is becoming possible with sub-micrometer spatial resolution and picogram-level sensitivity owing to advances in laser ablation MS, ion beam and synchrotron radiation X-ray fluorescence microprobes. Progress in nanoflow chromatography and capillary electrophoresis coupled with element specific ICP MS and molecule-specific electrospray MS/MS and MALDI enables speciation of elements in microsamples in a complex biological environment. Laser ablation ICP MS, micro-SXRF, and micro-PIXE allow mapping of trace element distribution in 1D and 2D proteomics gels. The increasing sensitivity of EXAFS and XANES owing to the use of more intense synchrotron beams and efficient focusing optics provide information about oxidation state, fingerprint speciation of metal sites and metal-site structures.     

Climatic limits for the present distribution of beech (Fagus L.) species in the world

Aim Beech (Fagus L., Fagaceae) species are representative trees of temperate deciduous broadleaf forests in the Northern Hemisphere. We focus on the distributional limits of beech species, in particular on identifying climatic factors associated with their present range limits. Location Beech species occur in East Asia, Europe and West Asia, and North America. We collated information on both the southern and northern range limits and the lower and upper elevational limits for beech species in each region. Methods In total, 292 lower/southern limit and 310 upper/northern limit sites with available climatic data for all 11 extant beech species were collected by reviewing the literature, and 13 climatic variables were estimated for each site from climate normals at nearby stations. We used principal components analysis (PCA) to detect climatic variables most strongly associated with the distribution of beech species and to compare the climatic spaces for the different beech species. Results Statistics for thermal and moisture climatic conditions at the lower/southern and upper/northern limits of all world beech species are presented. The first two PCA components accounted for 70% and 68% of the overall variance in lower/southern and upper/northern range limits, respectively. The first PCA axis represented a thermal gradient, and the second a moisture gradient associated with the world‐wide distribution pattern of beech species. Among thermal variables, growing season warmth was most important for beech distribution, but winter low temperature (coldness and mean temperature for the coldest month) and climatic continentality were also coupled with beech occurrence. The moisture gradient, indicated by precipitation and moisture indices, showed regional differences. American beech had the widest thermal range, Japanese beeches the most narrow; European beeches occurred in the driest climate, Japanese beeches the most humid. Climatic spaces for Chinese beech species were between those of American and European species. Main conclusions The distributional limits of beech species were primarily associated with thermal factors, but moisture regime also played a role. There were some regional differences in the climatic correlates of distribution. The growing season temperature regime was most important in explaining distribution of Chinese beeches, whilst their northward distribution was mainly limited by shortage of precipitation. In Japan, distribution limits of beech species were correlated with summer temperature, but the local dominance of beech was likely to be dependent on snowfall and winter low temperature. High summer temperature was probably a limiting factor for southward extension of American beech, while growing season warmth seemed critical for its northward distribution. Although the present distribution of beech species corresponded well to the contemporary climate in most areas, climatic factors could not account for some distributions, e. g., that of F. mexicana compared to its close relative F. grandifolia. It is likely that historical factors play a secondary role in determining the present distribution of beech species. The lack of F. grandifolia on the island of Newfoundland, Canada, may be due to inadequate growing season warmth. Similarly, the northerly distribution of beech in Britain has not reached its potential limit, perhaps due to insufficient time since deglaciation to expand its range.     

Convergence of chemical mimicry in a guild of aphid predators

Abstract.  1. A variety of insects prey on honeydew-producing Homoptera and many do so even in the presence of ants that tend, and endeavour to protect, these trophobionts from natural enemies. Few studies have explored the semiochemical mechanisms by which these predators circumvent attack by otherwise aggressive ants.
2. Ants use specific mixtures of cuticular hydrocarbons (CHCs) as recognition labels, but this simple mechanism is frequently circumvented by nest parasites that engage in 'chemical mimicry' of their host ants by producing or acquiring a critical suite of these CHCs.
3. Analysis of the CHCs from the North American woolly alder aphid, Prociphilus tessellatus (Homoptera: Aphididae), their tending ants, and aphid predators from three insect orders, Feniseca tarquinius (Lepidoptera: Lycaenidae), Chrysopa slossonae (Neuroptera: Chrysopidae), and Syrphus ribesii (Diptera: Syrphidae), showed that while the CHC profile of each predatory species was distinct, each was chemically more similar to the aphids than to either tending ant species. Further, the CHCs of each predator species were a subset of the compounds found in the aphids' profile.
4. These results implicate CHCs as a recognition cue used by ants to discriminate trophobionts from potential prey and a probable mechanism by which trophobiont predators circumvent detection by aphids and their tending ants.
5. Although several features of the aphids' CHC profile are shared among the chemically mimetic taxa, variation in the precision of mimicry among the members of this predatory guild demonstrates that a chemical mimic need not replicate every feature of its model.     

Differential activation of protein kinase C isoforms following chemical ischemia in rat cerebral cortex slices

The aim of the current study was to characterize the effects of chemical ischemia and reperfusion at the transductional level in the brain. Protein kinase C isoforms (, β₁, β₂, γ, δ and ) total levels and their distribution in the particulate and cytosolic compartments were investigated in superfused rat cerebral cortex slices: (i) under control conditions; (ii) immediately after a 5-min treatment with 10 mM NaN₃, combined with 2 mM 2-deoxyglucose (chemical ischemia); (iii) 1 h after chemical ischemia (reperfusion). In control samples, all the PKC isoforms were detected; immediately after chemical ischemia, PKC β₁, δ and isoforms total levels (cytosol + particulate) were increased by 2.9, 2.7 and 9.9 times, respectively, while isoform was slightly reduced and γ isoform was no longer detectable. After reperfusion, the changes displayed by , β₁, γ, δ and were maintained and even potentiated, moreover, an increase in β₂ (by 41 ± 12%) total levels became significant. Chemical ischemia-induced a significant translocation to the particulate compartment of PKC isoform, which following reperfusion was found only in the cytosol. PKC β₁ and δ isoforms particulate levels were significantly higher both in ischemic and in reperfused samples than in the controls. Conversely, following reperfusion, PKC β₂ and isoforms displayed a reduction in their particulate to total level ratios. The intracellular calcium chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid, 1 mM, but not the N-methyl-d-asparate receptor antagonist, MK-801, 1 μM, prevented the translocation of β₁ isoform observed during ischemia. Both drugs were effective in counteracting reperfusion-induced changes in β₂ and isoforms, suggesting the involvement of glutamate-induced calcium overload. These findings demonstrate that: (i) PKC isoforms participate differently in neurotoxicity/neuroprotection events; (ii) the changes observed following chemical ischemia are pharmacologically modulable; (iii) the protocol of in vitro chemical ischemia is suitable for drug screening.     

Chemical modification of siRNAs to improve serum stability without loss of efficacy

Development of RNA interference as a novel class of therapeutics requires improved pharmacokinetic properties of short interfering RNA (siRNA). To confer enhanced serum stability to Sur10058, a hyperfunctional siRNA which targets survivin mRNA, a systematic modification at the 2'-sugar position and phosphodiester linkage was introduced into Sur10058. End modification of three terminal nucleotides by 2'-OMe and phosphorothioate substitutions resulted in a modest increase in serum stability, with 3' end modification being more effective. Alternating modification by 2'-OMe substitution significantly stabilized Sur10058, whereas phosphorothioate modification was only marginally effective. Through various combinations of 2'-OMe, 2'-F and phosphorothioate modifications that were directed mainly at pyrimidine nucleotides, we have identified several remarkably stable as well as efficient forms of Sur10058. Thus, our results provide an effective means to stabilize siRNA in human serum without compromising the knockdown efficiency. This advancement will prove useful for augmenting the in vivo potency of RNA interference.