Mitochondrial DNA haplogrouping of the brown bear,Ursus arctos (Carnivora: Ursidae) in Asia,based on a newly developed APLP analysis

Sequence analyses of the complete brown bear, Ursus arctos, mitochondrial DNA (mtDNA) genome have detected scattered single nucleotide polymorphisms (SNPs) that define distinct mtDNA haplogroups in phylogeographical studies. The degraded DNA in historical samples, such as stuffed or excavated specimens, however, is often not suitable for sequence analyses. To address this problem, we developed an amplified product length polymorphism (APLP) analysis for mtDNA‐haplogrouping U. arctos specimens by detecting haplogroup‐specific SNPs. We verified the validity and utility of this method by analysing up to 170‐year‐old skin samples from U. arctos specimens collected widely across continental Eurasia. We detected some of the same haplogroups as those occurring in eastern Hokkaido (Japan) and eastern Alaska in continental Eurasia (the Altai and the Caucasus). Our results show that U. arctos in eastern Hokkaido and eastern Alaska descended from a common ancestor in continental Eurasia, and suggest that U. arctos occupied several refugia in southern Asia during the Last Glacial Maximum. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 627–635.     

EVOLUTION AND EXTINCTION IN A CHANGING ENVIRONMENT: A QUANTITATIVE-GENETIC ANALYSIS

Because of the ubiquity of genetic variation for quantitative traits, virtually all populations have some capacity to respond evolutionarily to selective challenges. However, natural selection imposes demographic costs on a population, and if these costs are sufficiently large, the likelihood of extinction will be high. We consider how the mean time to extinction depends on selective pressures (rate and stochasticity of environmental change, and strength of selection), population parameters (carrying capacity, and reproductive capacity), and genetics (rate of polygenic mutation). We assume that in a randomly mating, finite population subject to density-dependent population growth, individual fitness is determined by a single quantitative-genetic character under Gaussian stabilizing selection with the optimum phenotype exhibiting directional change, or random fluctuations, or both. The quantitative trait is determined by a finite number of freely recombining, mutationally equivalent, additive loci. The dynamics of evolution and extinction are investigated, assuming that the population is initially under mutation-selection-drift balance. Under this model, in a directionally changing environment, the mean phenotype lags behind the optimum, but on the average evolves parallel to it. The magnitude of the lag determines the vulnerability to extinction. In finite populations, stochastic variation in the genetic variance can be quite pronounced, and bottlenecks in the genetic variance temporarily can impair the population's adaptive capacity enough to cause extinction when it would otherwise be unlikely in an effectively infinite population. We find that maximum sustainable rates of evolution or, equivalently, critical rates of environmental change, may be considerably less than 10% of a phenotypic standard deviation per generation.     

Fluorescence anisotropy from diphenylhexatriene in rat liver plasma membranes

Rat livers were fractionated to obtain intracellular membrane preparations and a highly purified preparation of bile canaliculi. The fraction containing bile canaliculi was homogenized and subfractionated to give fractions representing fragments of contiguous membrane and of canalicular microvilli. The relative purity and extent of contamination of each preparation was determined. When the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene was incorporated into aliquots of each fraction at the same probe: lipid ratio and the steady-state anisotropy of its fluorescence measured, it was found that the plasma membrane preparations were much more ordered than the intracellular membrane preparations. Of the plasma membrane preparations, that containing the canalicular microvilli was the most ordered, even allowing for any contribution of contaminants. Thus the microvillus membrane of the bile canaliculus appears to be the most ordered domain of the plasma membrane of the hepatocyte. The high order in this domain may be a factor in reducing the susceptibility to bile salt damage during bile secretion, since it is this region which is exposed to high concentrations of bile salts in vivo.     

VARIATION IN ALCOHOL DEHYDROGENASE ACTIVITY AND FLOOD TOLERANCE IN WHITE CLOVER,TRIFOLIUM REPENS

Flooding results in induction of anaerobic metabolism in many higher plants. As an important component of anaerobic energy production, alcohol dehydrogenase (ADH) activity increases markedly in response to flooding in white clover, Trifolium repens. Significant inter-individual variation in flood-induced ADH activity exists in natural populations of T. repens. The genetic basis of this variation was analyzed by offspring-midparent regression of data from 75 greenhouse reared families; the estimated heritability of flood-induced ADH activity was 0.55 (±0.13). Genetic variation in flood-induced ADH activity has pronounced effects on physiological response and flood tolerance in this species. ADH activity is positively correlated with the rate of ethanol production, indicating that observed in vitro activity differences are manifested in in vivo physiological function. T. repens plants with higher ADH activities during flooding have greater flood tolerance (measured as growth rate when flooded/unflooded growth rate). Variation in ADH activity during flooding accounts for more than 79% of the variance in flood tolerance. On the basis of a limited field survey of populations occupying three sites differing in exposure to flooding conditions, individuals from site C, the most frequently flooded site, expressed significantly higher average ADH activity when flooded than individuals from site A, a site with no history of flooding. Since ADH activity levels are not correlated with electrophoretic mobility variation in T. repens, this work supports previous suggestions that regulatory variation in enzyme activity may play a central role in biochemical adaptations to environmental stress.     

A new approach to polarized fluorescence using phase and modulation fluorometry

In the preceding paper, an alternative method is described for obtaining information about the reorientational behavior of a fluorophore in a membrane system from frequency domain measurements. To demonstrate this new analysis procedure, we present data for the probe-molecule 1,6-diphenyl-1,3,5-hexatriene (DPH) in l--dimyristoyl- and l--dipalmitoylphosphatidylcholine (DMPC and DPPC) obtained with two different phase fluorometers: the SLM 4800A Subnanosecond Spectrofluorometer which has only three fixed frequencies available (6, 18 and 30 MHz) and the recently constructed continuously variable multifrequency phasefluorometer (Gratton and Limkeman 1983).It will be shown that reasonable information about the anisotropy behavior of a fluorophore can be obtained even if only three frequencies are used. The phase modulation technique was also used to check the new expression for the anisotropy, r(t), called the general model and introduced by Van der Meer et al. (1984). The parameters P ₂, P ₄ and D, obtained from the nonlinear least squares fit (Bevington 1969) for this general model, confirm the results from the pulse technique of Ameloot and coworkers (Ameloot et al. 1984; Pottel et al. 1986).     

重楼属植物甾体皂甙的高效液相色谱分析

应用高效液相层析技术,对重楼属十八个种植物的甾体皂甙进行了定性、定量分析。植物用甲醇提取,抽出物经DIAION柱,以90％甲醇洗出总甙。在HPLC上,用ODS柱先将总甙以用醇:水(9:1)洗脱分为三馏段,每馏再在ODS柱或Rp-8柱上以甲醇:水(8:2;7:3.5)洗脱,使各个皂甙成分完全分离。被分离的每个色谱峰与已知重楼皂甙的保留时间进行比较并配合HPLC的加入法,TLC分析及用HPLC制备少量样品做MS测定来加以定性鉴定。定量采用内标及校正曲线法。     

The analysis of planktonic rotifer populations: A plea for long-term investigations

Short-term species succession, and long-term community development, of planktonic rotifer populations of the temperate zone and factors influencing species' abundance (ie., physical and chemical limitations, food and exploitative competition, mechanical interference competition, predation, parasitism) are described and discussed. The long-term development of plankton communities in three European lakes is described and the major events are discussed in relation to ecological interactions. Frequently, the shortcomings of our knowledge about population ecology and ecophysiology of rotifers prevent explanations of short-term and, especially, of long-term developments of these plankton organisms. The need for qualitative and quantitative observations in the field and in the laboratory over long periods becomes obvious.