野生与栽培黄花蒿净光合速率对光强和CO2浓度的响应

比较了相同种源的野生和栽培黄花蒿(Artemisia annua L.)净光合速率对光强和CO2浓度的响应特性。结果表明,野生和栽培黄花蒿的光饱和点(LSP)分别为1 183和1 564μmol m-2s-1,光补偿点(LCP)为17和18μmol m-2s-1,最大净光合速率(Pmax)为18.78和22.38μmol m-2s-1,表观量子效率(AQY)为0.08和0.075μmol m-2s-1,表明黄花蒿的光合能力强,能够利用很高的光强,且对弱光的适应性也较强。栽培黄花蒿的Pmax、LSP和最大羧化速率(Vcmax)显著高于野生黄花蒿,两者的LCP、不包括光下呼吸的CO2补偿点、AQY、光下呼吸速率和最大电子传递速率(Jmax)差异不显著。强光下栽培黄花蒿主要通过提高Vcmax和Jmax等来增强光合能力,强的光合能力有利于黄花蒿的生长,因此在人工栽培黄花蒿的过程中应选择阳光充足的开阔生境。     

近视眼LASIK术后眼高阶像差变化

探讨近视眼LASIK术后眼波阵面像差高阶像差各项的变化。方法:采用NIDEK OPD-Scan ARK-1000型波前像差扫描系统对LASIK治疗近视的62只眼在术前术后眼的波前像差进行了评估。在术前、术后10天、术后一个月分别测量眼的波阵面像差。比较6mm瞳孔下高阶像差各项的变化。结果:在全部接受检查的病例中,总的高阶像差(RMSh)均有所增加。从Zernik各项绝对值来看,球差C12变化最大。术后10天比术前增加6．7742倍(P=0．0001)。其次是彗差C7 C8(X轴、Y轴上的彗差),分别增加了4．883倍(P=0．0001)、3．7523倍(P=0．0001)。结论:LASIK术后眼的总的高阶像差均方根值(RMSh)明显增加,尤其是球差和彗差;但在恢复过程中高阶像差有下降的趋势。用像差仪来指导和评估LASIK等屈光手术可以更全面、更准确。     

Hypoxia suppresses KV1.5 channel expression through endogenous 15-HETE in rat pulmonary artery

Hypoxia initiated pulmonary vasoconstriction is due to the inhibition of voltage-gated K(+) (K(V)) channels. But the mechanism is unclear. We have evidence that hypoxia activates 15-lipoxygenase (15-LOX) in distal pulmonary arteries and increases the formation of 15-hydroxyeicosatetraenoate (15-HETE). 15-HETE-induced pulmonary artery constriction to be through the inhibition of K(V) channels (K(V)1.5, K(V)2.1 and K(V)3.4). However, no direct link among hypoxia, 15-HETE and inhibition of K(V) subtypes is established. Therefore, we investigated whether 15-LOX/15-HETE pathway contributes to the hypoxia-induced down-regulation of K(V) channels. As K(V)1.5 channel is O(2)-sensitive, it was chosen in the initial study. We found that inhibition of 15-LOX suppressed the response of hypoxic pulmonary artery rings to phenylephrine. The expressions of K(V)1.5 channel mRNA and protein was robustly up-regulated in cultured PASMC and pulmonary artery after blocking of 15-LOX by lipoxygenase inhibitors in hypoxia. The 15-LOX blockade also partly rescued the voltage-gated K(+) current (I(K(V))). 15-HETE contributes to the down-regulation of K(V)1.5 channel, inhibition of I(K(V)) and increase of native pulmonary artery tension after hypoxia. Hypoxia inhibits K(V)1.5 channel through 15-LOX/15-HETE pathway.     

Karyotypic, palynological, and RAPD study on 12 taxa from two subsections of section Idaeobatus in Rubus L. and taxonomic treatment of R. ellipticus, R. pinfaensis, and R. ellipticus var. obcordatus

Twelve taxa belonging to two subsections of section Idaeobatus in Rubus L. from southwestern China were characterized by karyotypic, palynological, and random amplified polymorphic DNA (RAPD) data as follows: (1) The 12 taxa were all diploid species (2n = 2x = 14), among which the chromosome counts for R. mesogaeus var. oxycomus, R. subtibetanus, R. ellipticus var. obcordatus, R. inopertus var. echinocalyx, and R. stans were reported for the first time; (2) All taxa except for R. ellipticus and R. pinfaensis could be distinguished from each other by karyotype, pollen morphology, and RAPD markers. Karyotypes were mainly characterized by the difference in numbers and positions of submetacentric chromosomes and chromosomes with satellited pair, the index of the karyotypic asymmetry, and the ratio of the longest to the shortest chromosome. Pollen morphology were mainly characterized by the discrepancy in specific pollen size, P/E ratio, colpi width, distance between the apices of two ectocolpi, and exine ornamentation characters. The cluster results based on RAPD markers were consistent with morphology classification except for R. pinfaensis; (3) Based on the general data of karyotypic, palynological, and RAPD, R. ellipticus var. obcordatus should be treated as a species R. obcordatus, R. ellipticus and R. pinfaensis should be combined as R. ellipticus, and it was more reasonable to place the combinants and R. obcordatus into subsection Stimulantes rather than into subsection Pungentes.     

Dexamethasone upregulates mitochondrial Tom20, Tom70, and MnSOD through SGK1 in the kidney cells

Journal of Physiology and Biochemistry - Dexamethasone augments mitochondrial protein abundance. The translocase of the outer membrane (Tom) of mitochondria plays a major role in importing largely...     

Environmental constraints on the inter-genus variation in the scaling relationship between leaf nitrogen and phosphorus concentrations

环境因子对叶氮、磷含量异速生长关系的属水平差异的影响植物叶片中氮(N)、磷(P)含量的异速生长关系表明了植物对这两种元素的相对投入。而,现有的研究很少关注这一关系在分类单元之间的差异及其成因。本研究基于来自全国1733个样地,属于46个木本被子植物属的2483个叶片样品,利用异速生长方程([N] = α[P]^β)分别计算了各属的叶氮、磷含量异速生长指数(β_L)。然后利用谱系路径分析检验了这些属的气候和土壤生态位条件如何影响属间的β_L的差异。生活在贫磷土壤中的属更可能表现出更高的β_L,即相对于氮而言更强的磷积累,这可能表明了植物对磷限制的抵抗倾向。此外,各属的β_L与相对应的土壤氮、磷含量异速生长指数(β_S)正相关,这可能表明了叶养分的变化受制于作为来源的土壤养分的变化。最后,包括温度和湿度在内的气候因子不会直接影响β_L的属间变化,但可能通过调节土壤养分水平发挥间接的作用。谱系关系不会影响各属β_L随环境梯度的变化。这些结果揭示了植物对氮、磷摄取的权衡关系可能受属生态位,特别是土壤生态位的影响,表明了β_L可以作为一项反映植物养分利用特征如何响应生态位差异的功能属性。     

An asymmetric contribution to gamma-aminobutyric type A receptor function of a conserved lysine within TM2-3 of alpha1, beta2, and gamma2 subunits

Mutations that impair the expression and/or function of gamma-aminobutyric acid type A (GABAA) receptors can lead to epilepsy. The familial epilepsy gamma2(K289M) mutation affects a basic residue conserved in the TM2-3 linker of most GABAA subunits. We investigated the effect on expression and function of the Lys --> Met mutation in mouse alpha1(K278M), beta2(K274M), and gamma2(K289M) subunits. Compared with cells expressing wild-type and alpha1beta2gamma2(K289M) receptors, cells expressing alpha1(K278M)beta2gamma2 and alpha1beta2(K274M)gamma2 receptors exhibited reduced agonist-evoked current density and reduced GABA potency, with no change in single channel conductance. The low current density of alpha1beta2(K274M)gamma2 receptors coincided with reduced surface expression. By contrast the surface expression of alpha1(K278M)beta2gamma2 receptors was similar to wild-type and alpha1beta2gamma2(K289M) receptors suggesting that the alpha1(K278M) impairs function. In keeping with this interpretation GABA-activated channels mediated by alpha1(K278M)beta2gamma2 receptors had brief open times. To a lesser extent gamma2(K289M) also reduced mean open time, whereas beta2(K274M) had no effect. We used propofol as an alternative GABAA receptor agonist to test whether the functional deficits of mutant subunits were specific to GABA activation. Propofol was less potent as an activator of alpha1(K278M)beta2gamma2 receptors. By contrast, neither beta2(K274M) nor gamma2(K289M) affected the potency of propofol. The beta2(K274M) construct was unique in that it reduced the efficacy of propofol activation relative to GABA. These data suggest that the alpha1 subunit Lys-278 residue plays a pivotal role in channel gating that is not dependent on occupancy of the GABA binding site. Moreover, the conserved TM2-3 loop lysine has an asymmetric function in different GABAA subunits.     

The impacts of flowering phenology on the reproductive success of the narrow endemic Nouelia insignis Franch. (Asteraceae)

Nouelia insignis Franch. (Asteraceae) is a short, narrow endemic and endangered tree, growing with a natural population in the dry and hot valley of the Jinsha River in the southwest area of China. In this work, flowering phenology (time and duration), floral biology, visit frequency and behavior of pollinators, and pollination characteristics were studied based on investigation in the field and analysis in the laboratory with the help of a stereomicroscope, and the relationship between seed setting rate and reproductive traits, as well as the relationship between flowering time and rainfall before flowering, was tested using the method of general linear regression model. The results showed that natural population of N. insignis exhibited high flowering synchrony with relatively stable flowering duration, and the flowering time fluctuated greatly depending on the rainfall 5 months before flowering. The pollination of N. insignis required pollinators, and insect activities played a very important role in the pollination process. However, lack of the pollinators was not a limitation for reproductive fitness in N. insignis, although the number of pollinators was small and the frequency of visits was low. In addition, no pollen limitation was found during pollination. The average seed setting rate of N. insignis in the natural condition was only 1.52%–3.73%, and it was generally affected by changes in flowering phenology between years and had a higher seed set in early flowering year. The annual variation of seed set might be related to the annual variations of stamen and pistil functions, such as changes of pollen viability and stigma receptivity, which were closely related to flowering time. The results of this study are of value for further conservation actions on natural population of this threatened endemic plant.