外源Ca2+对高温强光胁迫下小麦叶绿体D1蛋白磷酸化及光系统Ⅱ功能的影响

用10 mmol·L^-1 CaCl₂溶液预处理灌浆期小麦叶片,以水预处理为对照,然后将预处理植株进行高温强光（35 ℃,1600 μmol·m^-2·s^-1）胁迫,测定胁迫处理过程中小麦旗叶光合电子传递速率、净光合速率、叶绿素荧光参数及D₁蛋白的变化,以研究外源Ca²⁺对高温强光胁迫下小麦叶片类囊体膜D₁蛋白磷酸化和PSⅡ功能的影响.结果表明：CaCl₂溶液预处理使小麦叶片在高温强光逆境下PSⅡ反应中心发生可逆失活,有效抑制了高温强光下D₁蛋白的净降解,保持了较高的D₁蛋白磷酸化水平,暗恢复后PSⅡ反应中心活性迅速恢复,全链电子传递速率和PSⅡ电子传递速率恢复至对照水平,维持了较高的PSⅡ原初光化学效率（F_v/F_m）、实际光化学效率(Ф_PSⅡ)、光化学猝灭系数（q_P）和净光合速率（P_n）.表明外源Ca²⁺通过调节小麦叶绿体D₁蛋白的周转,促进了PSⅡ的正常运转,减轻了高温强光胁迫对叶片光合机构的损伤.     

三种园林植物对夜间光照的响应与适应特征

光污染是城市生态系统中重要的污染类型,目前的研究集中在光污染对人类健康、昆虫生活史、生活习性、活动规律等方面,对植物生理生态的效应研究则较少。以凤仙花(Impatiens balsamina)、小叶栀子(Gardenia jasminoides)、夏菊(Dendranthema morifolium)为研究对象,研究白光LED灯从每天18:00—24:00照光(T1处理)、每天18:00—次日8:00照光(T2处理)以及自然光周期(CK)等3种光环境条件下,3种植物生物量积累与分配、开花特征、色素含量、碳氮含量及其比值(C/N比)、抗氧化酶等方面的响应与适应特征。结果表明,T1和T2处理增加了凤仙花的生物量(分别为CK的1.4和1.9倍),降低了叶片和茎的N含量,增加了叶片的C/N比(分别为CK的1.2和1.9倍),降低了叶片的色素含量;T1处理延迟了凤仙花的花期,T2处理条件下凤仙花不开花。T1和T2处理虽然没有影响小叶栀子的花期,但增加了花的数量,减小了花的平均重量,花的C/N比显著增加(T2处理为CK的1.3倍);T2处理降低了小叶栀子叶片的叶绿素a、b及总叶绿素含量,增加了丙二醛的含量(T2处理为CK的1.7倍)。夏菊的生物量及生理特征受到T1和T2处理的影响最小,但T1和T2处理均抑制了夏菊开花。这些结果表明凤仙花和夏菊开花对光污染引起光周期的变化比较敏感,凤仙花的生长和养分特征也受到夜间光照的显著影响,光污染对小叶栀子的叶片造成了显著伤害。总的来讲,与T2相比,T1处理对3种植物的负面影响较小,在城市照明的管理过程中,可以根据需要缩短夜间光照的时间,既可以节约能源,又可以减小对植物生理生态的负面影响。     

不同光脉冲方案对光下最大荧光参数及其计算参数的影响

光下最大荧光(F_m′)是植物生理生态研究中的重要参数,一般采用饱和脉冲(RF)方案来估计.然而,光系统Ⅱ(PSⅡ)受体库的反馈调节会影响RF方案对F_m′估计的准确性.为消除PSⅡ受体库反馈调节的影响,根据光脉冲强度(Q′)与叶绿素荧光(F′)的线性关系提出多相脉冲(MPF)方案,估算Q′无穷大时的F′(即F_m′).本研究采用MPF和RF方案分别对苦槠、青冈和乌桕3个树种叶片的叶绿素荧光和气体交换数据进行同步测量,并对两种方案估计的F_m′及其计算参数PSⅡ光化学效率(Φ_PSII)、PSⅡ的电子传递速率(J)、最大电子传递速率(J_max)、叶肉导度(g_m)和叶绿体内CO₂浓度(C_c)等光合参数进行比较,分析两种方案对3个树种叶片6个光合参数的影响.结果表明: 当光合有效辐射(PAR)<200 μmol·m^-2·s^-1时,两种方案对苦槠、青冈和乌桕叶片F_m′、Φ_PSII和J的估计无显著影响;当PAR>200 μmol·m^-2·s^-1时,采用MPF方案获得的苦槠、青冈和乌桕的F_m′分别比RF方案获得的F_m′高3.5%～5.2%、11.7%～18.0%和3.2%～7.1%;当PAR>200 μmol·m^-2·s^-1时,采用MPF方案获得的Φ_PSII、J和J_max分别不同程度地大于RF方案获得的参数,g_m和C_c分别不同程度地小于RF方案获得的参数.说明当PAR较低(<200μmol·m^-2·s^-1)时,MPF与RF方案对植物叶片F_m′、Φ_PSII、J的估计没有显著影响;当PAR较高(≥200μmol·m^-2·s^-1)时,MPF与RF方案对植物叶片F_m′、Φ_PSII、J、J_max、g_m和C_c的估计有显著影响,且RF方案对植物叶片的F_m′、Φ_PSII、J和J_max比MPF方案分别有不同程度的低估,对g_m和C_c则有不同程度的高估.     

夜间增温对亚高山针叶林主要树种无机氮吸收的影响

吸收营养物质是植物根系的主要生理功能。氮素吸收是植物体内氮代谢的第一步, 也是最关键的一步。为了全面地认识亚高山针叶林在全球气候变化背景下对两种主要无机氮(NH₄⁺和NO₃^-)吸收特点的变化, 该研究以川西亚高山针叶林优势树种——云杉(Picea asperata)和岷江冷杉(Abies fargesii var. faxoniana)为材料, 通过红外辐射加热器模拟增温, 利用非损伤微测技术(non-invasive micromeasurement technology)研究了这两个树种吸收NH₄⁺和NO₃^-特点的变化, 同时还探究了NH₄⁺和NO₃^- 之间的相互作用对植物吸收这两种离子的影响。研究结果显示: 在云杉根系中, NH₄⁺和NO₃^-的最大吸收速率分别发生在距离根尖最顶端17-18 mm区域和17 mm处, 而岷江冷杉对这两种离子的最大吸收速率分别发生在距离根尖顶端11 mm和11.5 mm处。增温对云杉和岷江冷杉根系吸收NH₄⁺和NO₃^-有促进作用。在增温条件下, NO₃^-能够促进云杉根系对NH₄⁺的吸收, 而NH₄⁺则抑制了其对NO₃^-的吸收。无论是否增温, 岷江冷杉对NH₄⁺的吸收都不受NO₃^-的影响, 而在增温条件下, NH₄⁺会抑制岷江冷杉对NO₃^-的吸收。     

Objective working hour characteristics and work–life conflict among hospital employees in the Finnish public sector study

This epidemiological cohort study, based on Finnish public sector data, investigated the associations between objective working hour characteristics and work–life conflict in day and shift work. The comprehensive data of hospital workers (n = 8 931, 92% women, average age 45 years), consisted of survey responses from 2012, linked with the payroll data of working hour characteristics from 91 days preceding the survey. Logistic regression analysis was used to investigate the associations between working hour characteristics and experiencing work–life conflict often/very often. The analyses were adjusted for age (< 39, 40–49 and >50 years), sex, level of education, marital status, number of small (0–6 years) and school-aged (7–18 years) children, and the overall stressfulness of the life situation. We also conducted stratified analyses of age and sex on the basis of significant interactions. Difficulties in combining work and life were more often associated with shift work without night shifts and shift work with night shifts than with day work (41% and 34 versus 27%; OR for shift work with night shifts 1.78, 95% CI 1.59–2.00, OR for shift work without night shifts 1.42, 95% CI 1.26–1.60). A high proportion (> 25%) of long (> 40h, (OR 1.26, 95% 1.14–1.39) and very long (> 48h, OR 1.31, 95% CI 1.15–1.49) weekly working hours were associated with work–life conflict, and in the stratified analysis, the latter was also true among women (OR 1.54, 95% CI 1.25–1.89). Of the unsocial working hour characteristics, a relatively large amount (> 10% of all shifts) of evening (OR 1.56, 95% CI 1.41–1.72) and night shifts (OR 1.46, 95%CI 1.32–1.61), a high proportion (> 25% of all shifts) of quick returns (< 11h) (OR 1.46, 95% CI 1.31–1.63), and weekend work (OR 1.44, 95% CI 1.31–1.58) were associated with work–life conflict. A large amount of single days off (> 25% of all days off) was associated with work–life conflict among men (OR 1.90, 95% CI 1.11–3.25), but not in the whole sample. When the two types of shift work were analyzed separately, shift work without night shifts and very long work weeks had higher odds (OR 1.47, 95% CI 1.20–1.80) of work–life conflict than shift work with night shifts. Conversely, weekend work and evening shifts had higher odds of work–life conflict among shift workers with night shifts (OR 1.74, 95% 1.55–1.96; (OR 1.57, 95% CI 1.40–1.77) than among those without night shifts. To conclude, this study shows that shift workers with and without night shifts more often have difficulties combining work and life than day workers. Several unsocial working hour characteristics, including long work weeks, evening and night shifts, weekend work, and quick returns, are associated with work–life conflict.     

The association between artificial light at night and prostate cancer in Gwangju City and South Jeolla Province of South Korea

Exposure to artificial light at night (ALAN) has been reported to be associated with various pathological changes including sleep deprivation, circadian rhythm disruption, and melatonin suppression with increase in various cancers such as breast or prostate cancers. In this study, we sought to elucidate the association between ALAN and prostate cancer in 27 districts within Gwangju City and urban and rural areas from South Jeolla Province in South Korea. We analyzed the correlation between ALAN and the incidence of a range of cancers by Poisson regression analysis, after adjustment for confounding risk factors, such as smoking, drinking, obesity, stress, air pollution (particulate matter <10 μm in diameter), urbanization (proportion of urbanized area), and the cancer screening rate. Interestingly, the incidence of prostate cancer was significantly associated with ALAN (risk ratio = 1.02, p = 0.0369) and urbanization (risk ratio = 1.06, p = 0.0055). In particular, comparing the prostate cancer incidence at 25% and 75% level of ALAN, the risk ratio was 1.726 (12.6 over 7.3, respectively). No significant association was observed between ALAN and other cancers, including stomach, esophageal, liver, pancreatic, laryngeal, lung and tracheal, bladder, and brain and central nervous system cancers, as well as lymphoma and multiple myeloma. In conclusion, this study shows that a high incidence of prostate cancer may be independently associated with light pollution and urbanization, which represent significant factors in the rapid process of industrialization of South Korea.     

The transition from day-to-night activity is a risk factor for the development of CNS oxygen toxicity in the diurnal fat sand rat (Psammomys obesus)

Performance and safety are impaired in employees engaged in shift work. Combat divers who use closed-circuit oxygen diving apparatus undergo part of their training during the night hours. The greatest risk involved in diving with such apparatus is the development of central nervous system oxygen toxicity (CNS-OT). We investigated whether the switch from day-to-night activity may be a risk factor for the development of CNS-OT using a diurnal animal model, the fat sand rat (Psammomys obesus). Animals were kept on a 12:12 light–dark schedule (6 a.m. to 6 p.m. at 500?lx). The study included two groups: (1) Control group: animals were kept awake and active during the day, between 09:00 and 15:00. (2) Experimental group: animals were kept awake and active during the night, between 21:00 and 03:00, when they were exposed to dim light in order to simulate the conditions prevalent during combat diver training. This continued for a period of 3?weeks, 5?days a week. On completion of this phase, 6-sulphatoxymelatonin (6-SMT) levels in urine were determined over a period of 24?h. Animals were then exposed to hyperbaric oxygen (HBO). To investigate the effect of acute melatonin administration, melatonin (50?mg/kg) or its vehicle was administered to the animals in both groups 20?min prior to HBO exposure. After the exposure, the activity of superoxide dismutase, catalase and glutathione peroxidase was measured, as were the levels of neuronal nitric oxide synthase (nNOS) and overall nitrotyrosylation in the cortex and hippocampus. Latency to CNS-OT was significantly reduced after the transition from day-to-night activity. This was associated with alterations in the level of melatonin metabolites secreted in the urine. Acute melatonin administration had no effect on latency to CNS-OT in either of the groups. Nevertheless, the activity of superoxide dismutase and catalase, as well as nitrotyrosine and nNOS levels, were altered in the hippocampus following melatonin administration. On the basis of these results, we suggest that a switch from diurnal to nocturnal activity may represent an additional risk factor for the development of CNS-OT. Utilizing a diurnal animal model may contribute to our understanding of the heightened risk of developing CNS-OT when diving with closed-circuit oxygen apparatus at night.     

Social facilitation is a better predictor of frog reproductive activity than environmental factors

Anuran breeding activity is frequently linked to environmental factors, mainly temperature and rainfall. However, a key feature of anuran reproductive behavior—gathering in choruses and producing loud advertisement calls to attract females—generates a conspicuous social cue that may also facilitate reproductive behavior. Here, I examine the relative importance of environmental and social factors in explaining the intensity of reproductive activity in the Neotropical treefrog Hypsiboas rosenbergi. I show that social cues generally play an important role, but that there are sex differences: male behavior is associated with a combination of environmental and social factors, while female behavior is associated almost exclusively with social cues. I discuss the potential benefits of using social cues in regulating breeding activity, and suggest that conservation efforts may take advantage of the apparently widespread pattern of social facilitation in anuran reproductive ecology.     

光照下菜豆叶片抗氰呼吸与光合作用关系的分析

为了进一步了解光照下植物呼吸作用的内在机理以及呼吸作用和光合作用的关系, 该文研究了在光照下菜豆(Phaseolus vulgaris)叶片抗氰呼吸与光合作用的关系。研究发现, 将黑暗下生长的菜豆幼苗叶片转到光照下10 h, 总呼吸、抗氰呼吸以及抗氰呼吸在总呼吸中的比例均逐步上升; 光照也导致了叶片叶绿体光合放氧和CO₂固定的出现及其速率的增加, 但光合放氧和CO₂固定速率的增加均滞后于抗氰呼吸的增加。将黑暗下生长的叶片转到光照下之前用抗氰呼吸的抑制剂水杨基氧肟酸(SHAM)处理叶片, 发现用SHAM处理并没有导致叶片在光照下光合放氧和CO₂固定速率的明显变化, 这也提示了黑暗下生长的叶片转至光照的过程中, 抗氰呼吸和光合作用没有产生偶联。进一步研究发现, 在黑暗中对叶片施加短时间的光照能够增加抗氰呼吸在总呼吸中的比例, 但短时间的光照对叶片光合CO₂固定速率没有影响。这些结果表明了光照对抗氰呼吸的诱导可以不依赖于光合作用, 光照可能是作为一种直接的信号去诱导抗氰呼吸。     

Comparative floral development in the tribe Mentheae (Nepetoideae: Lamiaceae) and its bearing on the evolution of floral patterns in asterids

A comparative developmental study of flowers was carried out using epi-illumination light microscopy on four genera of Lamiaceae (Nepeta, Rosmarinus, Salvia, andZiziphora), representing all three subtribes of Mentheae. All species examined share unidirectional (adaxial to abaxial) sepal initiation, except Rosmarinus, which has the reverse unidirectional sequence, starting abaxially. Initiated but suppressed bracteoles were detected only in Rosmarinus. In Rosmarinus, Salvia, and Ziziphora, initiation of petals and stamens proceeds unidirectionally from the abaxial side. Floral initiation of Nepeta has bidirectional inception of petals and unidirectional stamen initiation from the adaxial side. Temporal overlap in organ initiation between petal and stamen whorls occurs in all taxa, though this feature is more prominent in Rosmarinus. Significant structural and developmental features that distinguish the four genera include: (1) polysymmetric calyx tube, highly tomentose corolla and deeply four-partitioned ovary in Nepeta; (2) monosymmetric two-lipped calyx and shallowly four-partitioned ovary in Ziziphora; and (3) suppression of adaxial stamens in Salvia and Rosmarinus. Adaxial stamens are absent from Rosmarinus, but reduced stamens remain as staminodia in Salvia. In a phylogenetic context, the late monosymmetry of Nepeta and very early monosymmetry of Rosmarinus could both be regarded as derived conditions compared with the early monosymmetry ofSalvia and Ziziphora.