River corridor plants revisited: What drives their unique distribution patterns?

The phenomenon whereby some plant species display a river corridor distribution pattern has long been recognized but is still poorly understood. The goals of this study were to supplement the list of river corridor plants for Central Europe, analyse their habitats and compare their ecological features with those of their widely distributed counterparts. The ATPOL (Atlas of Poland) database was used to compile a list of river corridor plants of Poland and calculate their river corridor-specificity indices (RCSIs). The Ellenberg indicator values, dispersal modes and life forms of river corridor and widely distributed species were compared using generalized linear mixed models (GLMMs). Eighty-five species were classified as river corridor species. The most numerous habitat groups were meadow species (19%), wet-habitat therophytes (15%), riverside tall herbs (13%) and species of dry, sandy soils (12%). These species had mostly requirements for a higher temperature and alkalinity than widespread species. Among river corridor plants, there were a few eurytopic species. Corridor species had usually only one life form and less dispersal modes than widespread species. Hence, specific demands of corridor plants and lower phenotypic plasticity may explain their restricted geographical distribution. The definition of the river corridor plant species needs modification.     

Selecting a more realistic uncertainty factor: Reducing compounding effects of multiple uncertainties

Available toxicology datasets provide a unique opportunity to validate some of the currently used Uncertainty Factors in the development of acceptable exposure levels for noncancer effects. Toxicity studies from two separate sources, the FAO/WHO database on pesticides (1978–1987) and the Monsanto database (through 1988) were chosen to evaluate three of the five currently used Uncertainty Factors. Interspecies differences in NOELs between the three mammalian species evaluated are equal to or less than a factor of 10 for both the FAO/WHO data and the Monsanto data in greater than 90% of the cases evaluated. Median values for the comparison of interspecies NOELs were 3.0 or less for all comparisons except the comparison between the mouse and rat for the Monsanto dataset where the median value was 7.5. Analyses of the Monsanto toxicity database show that the reprotoxicity NOELs were always equivalent to or higher than the chronic or subchronic NOELs for the same material. Therefore, even without conduct of a specific study to address reproductive effects, reasonable protection from adverse reproductive effects can be afforded by use of either subchronic or chronic study NOELs without application of UFD. The median ratio of subchronic NOELs and chronic NOELs was 4, and for a majority of the studies the difference between the NOELs was within one order of magnitude. Our analysis aids in validating the assumption that the upperbound for individual uncertainties maybe accounted for by use of 10‐fold uncertainty factors. However, the current U.S. Environmental Protection Agency (USEPA) reference doses/concentrations may be overly conservative because upperbounds of each of the uncertainty factors are used and each of the uncertainty factors are considered to be independent variables. Because uncertainties are probably not independent variables, the influence of compounding upperbounds when multiple uncertainty factors are used is generally only considered when four or more areas of uncertainty are outstanding. When multiple uncertainties exist, we recommend upperbound estimates only be used for the first two Uncertainty Factors, and median values be used to account for the remaining uncertainties.     

Studies on the use of uncertainty factors in deriving RfDs

Risk assessment of exposure to chemicals having a toxic end point routinely uses the reference dose (RfD) approach based on uncertainty factors of 10. RfD model can be used with widely different databases. However, the quality of individual risk assessment is unequal among chemicals, often resulting in either an over‐ or underestimation of adverse health risk. The purpose of this investigation was to evaluate whether the magnitude of the 10X uncertainty factors has scientific merit against data from recent human and animal experimental studies. Although we assessed the use of uncertainty factors for representative chemicals from various classes of compounds, such as volatile organics, alcohols, gasoline components, and pesticides, we are presenting our findings for 24 chemicals.

A compilation and comparison of ratios between LOAEL/NOAEL (Lowest Observed Adverse Effect Level/No Observed Adverse Effect Level), and subchronic/chronic values were made. Although a 10X uncertainty factor is most commonly used in the risk assessment processes, an examination of the datasets which have been used to calculate RfDs suggests different values which are scientifically justifiable.     

A Flow Cytometric Analysis of the Nuclear 2C DNA Content in 17 Phaseolus Species (53 Genotypes)

The genus Phaseolus is characterized by a highly stable karyotype of 2n = 22. Despite this constancy, the size of the chromosomes varies, and crossing of species is possible only in a few cases. We determined the 2C nuclear DNA content of a number of Phaseolus species, cultivars and genotypes by flow cytometry, in order to realize the interspecific and intraspecific variation of the 2C value. The data range from 1.03 pg to 2.18 pg without any clear correlation to systematic relationships. The mean DNA values of wild and cultivated forms, as well as those of Andean and Mesoamerican genotypes, do not differ significantly. The variation is interpreted in terms of some nucleotypic adaptations. The data may be useful for molecular biological analyses, as well as for biotechnological and classical breeding programmes.     

Denaturant m values and heat capacity changes: relation to changes in accessible surface areas of protein unfolding.

Denaturant m values, the dependence of the free energy of unfolding on denaturant concentration, have been collected for a large set of proteins. The m value correlates very strongly with the amount of protein surface exposed to solvent upon unfolding, with linear correlation coefficients of R = 0.84 for urea and R = 0.87 for guanidine hydrochloride. These correlations improve to R = 0.90 when the effect of disulfide bonds on the accessible area of the unfolded protein is included. A similar dependence on accessible surface area has been found previously for the heat capacity change (delta Cp), which is confirmed here for our set of proteins. Denaturant m values and heat capacity changes also correlate well with each other. For proteins that undergo a simple two-state unfolding mechanism, the amount of surface exposed to solvent upon unfolding is a main structural determinant for both m values and delta Cp.     

基于BLUP育种值与GGE双标图分析杉木第三代全同胞家系生长性状的适生性

杉木Cunninghamialanceolata是中国南方重要的商品用材和碳汇造林树种。本研究以广东杉木33个第三代全同胞家系在不同生长地点的8年生径向生长表现(胸径)为基础开展多地点方差分析。结果表明,家系适生性遗传差异大(P<0.01),且地点、区组及地点与家系间的互作效应显著。采用基于个体模型的BLUP分析法计算每个试验地点参试家系的个体育种值,可将参试家系适生性进行初步划分,并筛选出个体育种值水平较高、适生性好的家系(家系1、4、13和31)。在此基础上,运用GGE双标图分析法进一步获得参试家系“哪个赢在哪里”功能图、不同家系高产性与稳产性结论、理想家系选择列表,发现家系1、4、13、31和其他家系适生性评价结果与BLUP分析结果基本一致,具有较好的分析效果。     

Different Ks values for hydrogen of methanogenic bacteria and sulfate reducing bacteria: An explanation for the apparent inhibition of methanogenesis by sulfate

Desulfovibrio vulgaris (Marburg) and Methanobrevibacter arboriphilus (AZ) are anaerobic sewage sludge bacteria which grow on H₂ plus sulfate and H₂ plus CO₂ as sole energy sources, respectively. Their apparent K_s values for H₂ were determined and found to be approximately 1 M for the sulfate reducing bacterium and 6 M for the methanogenic bacterium. In mixed cell suspensions of the two bacteria (adjusted to equal V _max) the rate of H₂ consumption by D. vulgaris was five times that of M. arboriphilus, when the hydrogen supply was rate limiting. The apparent inhibition of methanogenesis was of the same order as expected from the different K_s values for H₂. Difference in substrate affinities can thus account for the inhibition of methanogenesis from H₂ and CO₂ in sulfate rich environments, where the H₂ concentration is well below 5 M.     

Why there are no objective values: A critique of ethical intuitionism from an evolutionary point of view

Using concepts of evolutionary game theory, this paper presents a critique of ethical intuitionism, or non-naturalism, in its cognitivist and objectivist interpretation. While epistemological considerations suggest that human rational learning through experience provides no basis for objective moral knowledge, it is argued below that modern evolutionary theory explains why this is so, i.e., why biological organisms do not evolve so as to experience objective preferences and obligations. The difference between the modes of the cognition of objective and of valuative environmental attributes is explained with reference to different modes of natural selection acting on the cognitive apparatus of the organism. The negative implications are pointed out which the observable diversity of intraspecific behavioural adaptations and of cultural values has for the cognitivist, objectivist foundation of ethics. Eventually a non-cognitivist alternative to ethical intuitionism is outlined in terms of empirical authority relations, with the ritualisation of dominance-submission patterns as the evolutionary origin of human charismatic authority.