Photoinhibition and Photooxidation in Leaves of indica and  japonica Rice Under Different Temperatures and Light Intensities

Physiological indices related to the efficiency （ Fv/Fm ） of light energy conversion in PSⅡ and the peroxidation of membrane lipid were measured in leaves of Oryza sativa L. sp. indica rice cv. “Shanyou 63” and sp. japonica rice cv. “9516” under different temperatures and light intensities for 4 days. No changes in Fv/Fm and membrane lipid peroxidation product (MDA) were observed, so neither photoinhibition nor photooxidation happened in both rice cultivars under moderate temperature and medium light intensity. However, Fv/Fm dropped obviously with no change in MDA contents, and photoinhibition appeared in indica rice cv. “Shanyou 63” under medium temperature and strong light intensity. Furthermore, both photoinhibition and photooxidation were observed in two rice cultivars under chilling temperature and strong light intensity. Experiments with inhibitors under chilling temperature and strong light intensity showed that indica rice had a decrease in D1 protein content and SOD activity, and the extent of inhibition of xanthophyll cycle and nonphotochemical quenching ( qN ) was larger, and a higher level of MDA was observed. The photoinhibition and photooxidation in indica rice were more distinct as compared with japonica rice. The authors suggested that PSⅡ light energy conversion efficiency ( Fv/Fm ) and membrane lipid peroxidation were the key indices for the detection of photooxidation.     

Kinetic Fluorescence Spectral Analysis of Core Antennas CP43 and CP47 of Photosystem Ⅱ with Ultrafast Time-resolved Technology

Ultrafast time-resolved fluorescence experiments have been performed with core antennas CP43 and CP47 of PS Ⅱ. Their dynamic fluorescence spectra were obtained with excitation wavelength 514.5 nm. For CP43, the emission spectrum was found to be from 640 to 780 nm with a peak at ～680 nm and the lifetime of fluorescence was 3.54 ns. For CP47, the emission spectrum was from 630 to 775 nm with a peak at ～691 nm and the fluorescence lifetime was 3.22 ns. The fluorescence emission efficiencies of Chl a in CP43 and CP47 were calculated to be approximately 38.3% and 40.6%, respectively. The energy transfer from β-Car to Chl a in CP43 and CP47 was discussed. The rates of energy transfer from β-Car to Chl a were measured to be about 9.6×1011 s-1 and 1.3×1012 s-1 and energy transfer efficiencies 47.5% and 66.5% respectively. The edge-edge distances between β-Car and Chl a in CP43 and CP47 were estimated to be ～0.110 nm and ～0.085nm respectively.     

Singlet Oxygen Generated in PS￠ò Particles Promotes the Superoxide Generation

The relationship between superoxide and singlet oxygen in PSⅡ particle of spinach under strong illumination was studied with spin-trap ESR technique. The generation of superoxide was increased under D2 environment which prolonged the half life of singlet oxygen. The generation of superoxide was decreased when histidine existed as a scavenger of singlet oxygen. It is highly possible that the superoxide generated in PSⅡ particle originates from singlet oxygen.     

薇甘菊叶和茎的光合特性

薇甘菊(Mikania micranth)是世界性的入侵有害植物,对其入侵特性的理解将有助于我们更进一步揭示入侵机理和开展植物入侵的防治工作。叶片的光合作用是入侵植物薇甘菊入侵特性的研究内容之一,但到目前为止,仍没有开展对薇甘菊非同化器官茎的同化特性的研究。该文采取对比的研究方法,使用LICOR-6400气体交换系统和荧光系统对其幼嫩的绿色茎和成熟叶片的气体交换和叶绿素荧光特性进行测定,并对测定结果进行了对比分析,同时应用激光共聚焦显微镜对薇甘菊茎中叶绿体分布进行观察。使用叶绿素荧光系统测量瞬时叶绿素荧光特性表明,茎和叶的电子传输速率(Electron transport rate, ETR)和光系统Ⅱ实际光化学量子产量(Φ_PSⅡ)存在较好的正比例关系,相关系数达到0.97,说明茎中存在和叶中类似的光合结构。但在应用LICOR-6400气体交换系统测量稳定状态下的CO₂的气体交换速率时,观察到叶的气体交换速率稳定性较好,而茎的气体交换速率出现较大的波动,这可能是由于茎的气孔因素引起。综合来看,在相同面积和饱合光强下(光通量密度(Photosynthetic photo flux density, PPFD)=2 000 μmol·m ^-2·s^-1),叶的ETR为42.44 μmol·m ^-2·s^-1,茎的ETR为30.32 μmol·m ^-2·s^-1。在相同面积和低光强(PPFD=10 μmol·m ^-2·s^-1)下,叶的Φ_PSⅡ为0.69;茎的Φ_PSⅡ为0.57。在单位SPAD下,茎中ETR是每单位SPAD 4.24 μmol·m ^-2·s^-1,是叶的2.3倍,实际光化学量子产量是每单位SPAD 0.08,是叶的3倍。在比较茎和叶ETR中观察到茎比叶有更强的强光适应能力。激光共聚焦图像观察到薇甘菊茎的叶绿体主要分布在两个区域:皮层区和维管束周围。对照以往关于茎中叶绿体功能的研究表明,可能分布在两个区域中的叶绿体功能上存在差别。如上,薇甘菊茎中存在一定的光合作用能力,且在叶绿体的光能利用瞬时效率上茎明显强于叶,但在茎中这些光合作用的具体作用仍不清楚。     

高温对水稻开花期剑叶抗氧化酶活性及基因表达的影响

以杂交水稻‘Ⅱ优838’为研究材料,检测了高温胁迫下‘Ⅱ优838’开花期剑叶中叶绿素含量、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)活性及SOD、CAT、POD基因的表达水平。结果显示,高温胁迫使‘Ⅱ优838’剑叶中叶绿素含量及叶绿素a和叶绿素b含量的比值(Chl a/Chl b)降低且下降幅度显著低于‘冈优725’(对照);SOD和POD活性增高且增幅显著大于‘冈优725’,但CAT活性降低且降幅显著小于‘冈优725’;热胁迫使‘Ⅱ优838’剑叶中SOD、CAT和POD基因的表达量显著增加。说明‘Ⅱ优838’在开花期遭遇高温胁迫后能保持较高的光合效率,并通过提高抗氧化保护酶的基因表达水平以维持较高的活性来应答高温胁迫,这为深入剖析水稻高温胁迫下的生理反应和适应机理提供了参考。     

基于LANDIS-II的陕西黄龙山森林景观演变动态模拟

应用空间直观景观模型LANDIS-II模拟了陕西黄龙山森林景观在不考虑风、火、病虫害及采伐等干扰因素前提下300a(2004—2304年)的自然演替进行动态,采用景观格局统计软件APACK计算了林区内优势树种所占的面积百分比以及反映物种分布格局的聚集度指数,分析了各个树种在模拟的时间尺度上龄级组成的变化趋势。结果表明:油松是针叶树中的优势种,辽东栎是阔叶树中的优势种;在演替后期油松取代辽东栎成为所占面积比例最大的优势树种;油松和辽东栎的相对聚集度较其它几类树种小;随着模拟年代的推进,树种年龄结构发生显著变化,呈现出复杂多样的异龄林空间分布格局。     

血清降钙素原在感染性休克患者中的表达及与APACHEⅡ评分的相关性分析

目的:探讨血清降钙素原在感染性休克患者中的表达及与APACHEⅡ评分的相关性分析。方法:选取2012年1月至2013年9月我院收治的58例感染性休克患者,设为感染性休克组,早期采取液体复苏的方法进行救治。另选取同期于我院体检的年龄、性别与之相匹配的52例健康人设为对照组。测定两组不同时间的血清PCT含量,对APACHEⅡ评分进行评定,并进行统计学分析。结果:感染行休克组患者的复苏液体量最少为4332mL,最多为10645mL,平均为(7602.85±1628.47)mL,复苏达标的平均时间为(17.67±3.75)h。感染性休克组患者血清PCT含量治疗后24h为(8.77±4.66)μg/L,明显低于治疗前的(17.78±5.89)μg/L;感染性休克组患者治疗前与治疗后24h血清PCT含量相比于对照组受试者的(0.03±0.01)μg/L均显著提高;感染性休克组患者治疗前与治疗后24hAPACHEⅡ评分分别为(16.68±3.27)分、(10.46±3.18)分,相比于对照组的(7.22±1.15)分均显著提高;感染性休克组患者APACHEⅡ评分治疗后24h明显低于治疗前。差异有统计学意义(P0.05)。感染性休克组治疗前后PCT含量与APACHEⅡ评分均呈一定的正相关(P0.05);PCT含量变化与快速复苏的液体量呈一定的负相关(P0.05);而与APACHEⅡ评分不存在明显的相关性(P0.05)。结论:将血清降钙素原应用于感染性休克患者的诊断及治疗过程中评估病情变化,能够为液体复苏提供有效的指导。血清降钙素原含量与APACHEⅡ评分呈正相关,但其变化与APACHEⅡ评分不存在相关性,而与复苏液体量呈负相关。     

ACEI/ARB对糖尿病肺病的影响

近年来,糖尿病肺部病变越来越受到关注。研究发现糖尿病患者存在肺通气功能障碍、弥散功能障碍,易于发生肺纤维化、合并感染等。这主要与糖尿病时炎症介质的参与,ACE基因存在插入多态性,氧化应激损伤和抗氧化失衡等有关。目前研究发现血管紧张素转换酶抑制剂（ACEI）/血管紧张素受体阻滞剂（ARB）对糖尿病肺炎、慢性阻塞性肺疾病、肺间质纤维化等肺损伤有保护作用,这可能与ACEI具有调节免疫反应、减轻细胞因子水平、抗氧化应激损伤等机制有关。     

成人骨性Ⅱ类上气道与颅颌面关系初探

目的:比较骨性Ⅱ类不同垂直骨面型成人上气道鼻咽、腭咽、舌咽大小的差异,并探讨其与颅面部骨骼形态的关系.方法:将64名(男34例,女30例)成人骨性Ⅱ类错患者按GoGn-SN角大小分为高角、均角、低角三组.分别行颅面部锥体束计算机断层扫描(CBCT),对各段的矢状径、横径、长度、截面积以及容积等指标进行测量分析,比较三组间的差异.同时,对上气道各测量项目与颅颌面结构指标进行相关性分析.结果:在上气道各线性测量项目中,鼻咽和腭咽长度(Ln、Lp)随着垂直骨面型增大而逐渐减小,差异有统计学意义(P＜0.05).高角组舌咽段的高度(Hg)与均角、低角组存在差异,差异有统计学意义(P＜0.05),均角组和低角组间并无统计学差异(P＞0.05).上气道各段宽度在不同垂直骨面型之间均无统计学差异.不同垂直骨面型上气道总体积(Vt)无明显差异.高角组舌咽段体积(Vg)及鼻咽段横截面积(CSAn)与均角、低角组存在差异,差异有统计学意义(P＜0.05),均角组和低角组间并无统计学差异(P＞0.05).而其余测量项目在各垂直骨面型间均未发现统计学差异.由相关性分析可知,舌咽和腭咽的体积与横截面积与上下颌骨垂直向不调指数(ODI)正相关,而腭咽体积和横截面积与下颌平面角负相关.结论:随着垂直骨面型增大上气道结构存在着差异,且主要影响腭咽段和舌咽段,对鼻咽段影响较小.