[Genetic diversity and genetic differentiation of Rhododendron concinnum wild populations in Qinling Mountains of Northwest China: an AFLP analysis].

By using amplified fragment length polymorphism (AFLP) technique, an investigation was made on the genetic diversity and genetic differentiation of seven wild populations of Rhododendron concinnum in Qinling Mountains of Northwest China. A total of 182 amplification products were generated from three AFLP selective primer combinations, of which, 151 were polymorphic. The percentage of polymorphism was 83.1%. The change trends showed by the percentage of polymorphic loci (PPL), Nei's gene diversity (h), and Shannon's information index (I) were uniform, and the order of the populations was Meixian > Zhashui > Zhen' an > Huxian > Ningqiang > Nanzheng > Zhouzhi. The POPGENE analysis showed that the R. concinnum had higher genetic diversity at both species level (PPL = 91.22%, I = 0.7217, h = 0.5095) and population level (PPL = 77.56%, I = 0.6409, h = 0.4725). The coefficient of gene differentiation among the populations (Gst) was 0.0726, indicating that 92.74% of genetic variation occurred within the populations. The analysis of molecular variance (AMOVA) showed that 85.3% of the genetic variation was within the populations, and 14.7% of it was among the populations. The unweighted pair group method with arithmeticmean (UPGMA) indicated that there was no significant correlation between the genetic distance and the geographic distance among the R. concinnum populations. The conservation strategies for R. concinnum germplasm resources were put forward.

Effect of flow shear stress gradient on the arrangement and shape of endothelial cells / 医用生物力学

Objective The effect of different flow shear stress gradient on the changes of arrangement and shape of endothelial cells was evaluated in order to investigate the effect of shear stress gradient on ECs morphology and function. Method A flow chamber system with gradient shear stress was established, in which the range of shear stress is from 15 dyn/cm2 to 6.6 dyn/cm2(1 dyn=10-5 N), and the shear stress gradient is 1.5 dyn/cm2 and 3 dyn/cm2 respectively. After ECs were subjected to the gradient shear stress for 6 hours, cell angle, cell width length ratio, as well as cell shape index of ECs under the different shear stress gradient were examined. Results The cell angles of ECs were straggling under both 1.5 dyn/cm2 and 3 dyn/cm2 shear stress gradient. The cell width length ratio and cell shape index of ECs were decreased under 1.5 dyn/cm2 shear stress gradient compared with that of 3 dyn/cm2 shear stress gradient. Conclusions The ECs show random orientation under the different shear stress gradient. The ECs are trending to stretch and elongate shape under smaller shear stress gradient, and to approach cycloid under larger shear stress gradient.