Population structure and historical demography of Dipteronia dyeriana (Sapindaceae), an extremely narrow palaeoendemic plant from China: implications for conservation in a biodiversity hot spot.

Inferring past demography is a central question in evolutionary and conservation biology. It is, however, sometimes challenging to disentangle their roles of contemporary versus historical processes in shaping the current patterns of genetic variation in endangered species. In this study, we used both chloroplast microsatellite (cpSSR) loci and nuclear microsatellite (nSSR) loci to assess the levels of genetic differentiation, genetic effective population size, contemporary/historical levels of gene flow and demographic history for five populations sampled across the range of Dipteronia dyeriana, an endangered palaeoendemism from Southwestern China. We found that D. dyeriana had a mixed pattern of moderate genetic diversity and high inbreeding. Bayesian clustering divided D. dyeriana populations into two nSSR genetic clusters. Coalescent-based approximate Bayesian computation analyses suggest the western and eastern groups of D. dyeriana likely persisted in a long-term refuge in Southern China since the beginning of the last glacial period, whereas increasingly colder and arid climates at the onset of the last glacial maximum might have fostered the fragmentation of D. dyeriana within refugia. Following their divergence, the western group kept relatively stable effective population size, whereas the eastern group had experienced 500-fold population expansion during the Holocene. Although clear loss of genetic diversity by human activities was not suggested, recent habitat fragmentation has led to a reduction of population connectivity and increased genetic differentiation by ongoing genetic drift in isolated populations, possibly owing to decreased population size in recent dozen years. Finally, we discussed the implications of these results on conservation policies.

Observation of B+/- -->omegaK+/- decay.

We report the first observation of the charmless two-body mode B+/--->omegaK+/- decay, and a new measurement of the branching fraction for the B+/--->omegapi(+/-) decay. The measured branching fractions are B(B+/--->omegaK+/-)=(9.2(+2.6)(-2.3)+/-1.0)x10(-6) and B(B+/--->omegapi(+/-))=(4.2(+2.0)(-1.8)+/-0.5)x10(-6). We also measure the partial rate asymmetry of B+/--->omegaK+/- decays and obtain A(CP)=-0.21+/-0.28+/-0.03. The results are based on a data sample of 29.4 fb(-1) collected on the Upsilon(4S) resonance by the Belle detector at the KEKB e(+)e(-) collider.

[Differential pulse voltammetric measurements of cholesterol based on its oxidation after adsorption at the mercury electrode].

Cholesterol can be adsorbed on the surface of the static mercury drop electrode, and then oxidized during anodic potential scan. The stripping peak potential in differential pulse voltammetry is at -0.08 V in 0.1 mol/L K2HPO4-KH2PO4 buffer solution. The stripping current is linear with the concentration of cholesterol in the range of 10(-7)-10(-6) mol/L. The detection limit found is 8 x 10(-8) mol/L after a 5 min pre-concentration period. The adsorption and oxidation mechanisms of cholesterol at the mercury electrode were then explored. The experimental conditions for measuring free cholesterol in human sera were examined.

[Adsorptive stripping voltammetry of chlorprothixene at glassy carbon electrode].

A new electrochemical stripping method for measuring the antipsychotic drug chlorprothixene was reported. The drug, which was adsorbed on the surface of glassy carbon electrode, showed a sharp oxidative stripping peak at about +0.7 V (vs. Ag-AgCl) in voltammetry. The response was linear over the 0.01-1 microgram/ml concentration range. The detection limit was 2 ng/ml, about 400 times higher than UV method. The electrode surface was polished with alumina between the measurements to activate the electrode and provide good reproducibility. The open circuit accumulation/medium exchange/stripping voltammetry scheme has been proposed to avoid interference. The method has been used for direct determination of chlorprothixene in tablets and urine samples.

[Stripping voltammetric determination of perphenazine and some antipsychotic drugs at carbon paste electrodes].

A sensitive electrochemical method for the determination of four drugs: perphenazine, fluphenazine chlorpromazine and trifluperazine is reported. These compounds exhibited accumulation at carbon paste electrodes in an open circuit. Differential pulse voltammetric determination gave linear calibration curves in the range of 0.02-1 microgram/ml. Detection limits found were 5-7 ng/ml. The drugs in tablets and body fluids were determined directly without separation. The preconcentration mechanism and determination conditions in a new kind of carbon paste piston electrode were investigated. Adsorption and extraction played important roles in accumulation process and the ratio of these two parts was measured by chronocoulometry.