Influence of root-zone temperature on growth,development and yield of cucumber plants cv. Toska

Summary In a first experiment, cucumber transplants (cucumis sativa L. cv. Toska) were grwon at five root-zone temperatures (RZT) ranging from 12° to 36°C. Maximum shoot growth and total leaf area were obtained at 24° and 30°C (RZT). In a second experiment, cucumber transplants were submitted to five RZT (12, 18, 24, 30 and 36°C) and five night air temperatures (NAT) that were maintained either constant at 9°, 13° and 17°C or splitted (in two halfs) at midnight (17°/12°C, 17°/9°C). Root-zone warming to 24° or 30°C increased cucumber plant growth and leaf development, but did not compensate completely the loss of productivity induced by low NAT. Split-night temperature had greater effects under the lowest NAT (17°/9°C) and at high RZT (24° or 30°C). In a third experiment, soil warming caused large increase in yields when cucumber plants were grown in the spring, but had very little effects in the fall.     

夜鹭种群越冬生态学的研究

198 3- 12～ 1984- 0 5对聚集在上海西郊的 15 0 0只越冬夜鹭进行研究 ,又在 1998～ 1999年的相应月份进行了复查和研究。研究结果 :①夜鹭越冬种群在 12～ 1月达到高峰 ,数量为 (15 31± 2 75 )只 ;幼 /成比为 1 73∶1± 0 0 35。 3月中旬 ,夜鹭成鸟开始迁离越冬区 ,至 4月初绝大部分已迁飞 ;而幼鸟是在 4月中旬开始迁离本地。②光照强度是控制夜鹭活动的主要因子。夜鹭在黄昏 4 3～ 0 48lx时飞离栖息地 ,在黎明前 0 2lx时返回。随着夜长日短 ,夜鹭有提前集群飞离、延迟返回的倾向。③夜鹭在越冬数量高峰期的种群分布为均匀分布 ,在数量下降的迁徙期为集群分布 ,这与栖息地的环境容量和夜鹭集群方式有关 ;研究表明 ,夜鹭很可能以家族的形式将栖息点固定下来。④风是影响夜鹭栖息点分布的主要因素 ,其他气候因子影响不明显     

无锡太湖地区夜鹭及白鹭繁殖生物学研究

1999年 4～ 6月对分布在无锡地区的夜鹭 (Nycticoraxnycticorax)和白鹭 (Egrettagarzetta)的繁殖生物学进行了调查研究 ,调查地面积约 2 72 37 5m2 ,植被以马尾松 (Pinusmassoniana)和香樟树 (Cinnamomumhupehanum)为主。研究结果表明 :栖息地共有鹭巢近万个 ,平均密度为 0 36个 /m2 ,每棵树上平均巢数为1 0 6个 ,最多达 2 5个 /棵树 ;平均窝卵数夜鹭为 3 5 5枚 ,白鹭为 4 89枚 ;平均窝雏数夜鹭为 2 6 8只 ,白鹭为3 96只 ;孵化期白鹭为 1 9～ 2 1天 ,夜鹭为 2 2～ 2 3天 ;孵化成功率白鹭为 84 2 5 % ,夜鹭为 75 46 % ;白鹭雏鸟主要以小型鱼类和虾类为食 ,夜鹭雏鸟主要以鱼类和两栖类为食。     

Docking of human rhodopsin mutant (Gly90→Asp) with beta-arrestin and cyanidin 3-rutinoside to cure night blindness

MOTIVATION: Rhodopsin is a visual pigment present in rod cells of retina. It belongs to GPCR family and involves photoisomerization of 11-cis-retinal to all-trans-retinal isomers, conformational changes in rhodopsin and signal transduction cascade to generate a nerve impulse. This signaling pathway has been targeted to eliminate the effect of a mutation (Gly90→Asp) responsible for abnormal activation of G-protein without retinal conformations in the absence of light leading to congenital night blindness. A theoretical model of rhodopsin with induced mutation has been deliberated in order to find potential ligands which can offset this mutational effect. The binding interactions between the target mutated rhodopsin model and potential ligands have been predicted with the help of molecular docking. The results indicated strong functional benefits of ligands as an inhibitor and an agonist for mutated rhodopsin model. Therefore, we propose a new visual cascade model which can initiate the normal signaling of rhodopsin mutant with the help of proposed ligands and can provide a hope for vision in future.     

Controlled exposure to light and darkness realigns the salivary cortisol rhythm in night shift workers

The efficacy of a light/darkness intervention designed to promote circadian adaptation to night shift work was tested in this combined field and laboratory study. Six full-time night shift workers (mean age ± SD:37.1 ± 8.1 yrs) were provided an intervention consisting of an intermittent exposure to full-spectrum bright white light (∼2000 lux) in the first 6 h of their 8 h shift, shielding from morning light by tinted lenses (neutral gray density, 15% visual light transmission), and regular sleep/darkness episodes in darkened quarters beginning 2 h after the end of each shift. Five control group workers (41.1 ± 9.9 yrs) were observed in the presence of a regular sleep/darkness schedule only. Constant routines (CR) performed before and after a sequence of ∼12 night shifts over 3 weeks revealed that treatment group workers displayed significant shifts in the time of peak cortisol expression and realignment of the rhythm with the night-oriented schedule. Smaller phase shifts, suggesting an incomplete adaptation to the shift work schedule, were observed in the control group. Our observations support the careful control of the pattern of light and darkness exposure for the adaptation of physiological rhythms to night shift work.     

Circadian Phase,Sleepiness, and Light Exposure Assessment in Night Workers With and Without Shift Work Disorder

Most night workers are unable to adjust their circadian rhythms to the atypical hours of sleep and wake. Between 10% and 30% of shiftworkers report symptoms of excessive sleepiness and/or insomnia consistent with a diagnosis of shift work disorder (SWD). Difficulties in attaining appropriate shifts in circadian phase, in response to night work, may explain why some individuals develop SWD. In the present study, it was hypothesized that disturbances of sleep and wakefulness in shiftworkers are related to the degree of mismatch between their endogenous circadian rhythms and the night-work schedule of sleep during the day and wake activities at night. Five asymptomatic night workers (ANWs) (3 females; [mean?±?SD] age: 39.2?±?12.5 yrs; mean yrs on shift?=?9.3) and five night workers meeting diagnostic criteria (International Classification of Sleep Disorders [ICSD]-2) for SWD (3 females; age: 35.6?±?8.6 yrs; mean years on shift?=?8.4) participated. All participants were admitted to the sleep center at 16:00?h, where they stayed in a dim light (<10 lux) private room for the study period of 25 consecutive hours. Saliva samples for melatonin assessment were collected at 30-min intervals. Circadian phase was determined from circadian rhythms of salivary melatonin onset (dim light melatonin onset, DLMO) calculated for each individual melatonin profile. Objective sleepiness was assessed using the multiple sleep latency test (MSLT; 13 trials, 2-h intervals starting at 17:00?h). A Mann-Whitney U test was used for evaluation of differences between groups. The DLMO in ANW group was 04:42?±?3.25?h, whereas in the SWD group it was 20:42?±?2.21?h (z = 2.4; p?<?.05). Sleep did not differ between groups, except the SWD group showed an earlier bedtime on off days from work relative to that in ANW group. The MSLT corresponding to night work time (01:00–09:00?h) was significantly shorter (3.6?±?.90?min: [M?±?SEM]) in the SWD group compared with that in ANW group (6.8?±?.93?min). DLMO was significantly correlated with insomnia severity (r = ?.68; p < .03), indicating that the workers with more severe insomnia symptoms had an earlier timing of DLMO. Finally, SWD subjects were exposed to more morning light (between 05:00 and 11:00?h) as than ANW ones (798 vs. 180 lux [M?±?SD], respectively z?=??1.7; p?<?.05). These data provide evidence of an internal physiological delay of the circadian pacemaker in asymptomatic night-shift workers. In contrast, individuals with SWD maintain a circadian phase position similar to day workers, leading to a mismatch/conflict between their endogenous rhythms and their sleep-wake schedule. (Author correspondence: vgumeny1@hfhs.org)     

Factors Associated With Shift Work Disorder in Nurses Working With Rapid-Rotation Schedules in Japan: The Nurses’ Sleep Health Project

Workers who meet the criteria for shift work disorder (SWD) have elevated levels of risk for various health and behavioral problems. However, the impact of having SWD on shiftworkers engaged in rapid-rotation schedules is unknown. Moreover, the risk factors for the occurrence of SWD remain unclear. To clarify these issues, we conducted a questionnaire-based, cross-sectional survey on a sample of shiftworking nurses. Responses were obtained from 1202 nurses working at university hospitals in Tokyo, Japan, including 727 two-shift workers and 315 three-shift workers. The questionnaire included items relevant to age, gender, family structure, work environment, health-related quality of life (QOL), diurnal type, depressive symptoms, and SWD. Participants who reported insomnia and/or excessive sleepiness for at least 1 mo that was subjectively relevant to their shiftwork schedules were categorized as having SWD. The prevalence of SWD in the sampled shiftworking nurses was 24.4%; shiftworking nurses with SWD showed lower health-related QOL and more severe depressive symptoms, with greater rates of both actual accidents/errors and near misses, than those without SWD. The results of logistic regression analyses showed that more time spent working at night, frequent missing of nap opportunities during night work, and having an eveningness-oriented chronotype were significantly associated with SWD. The present study indicated that SWD might be associated with reduced health-related QOL and decreased work performance in shiftworking nurses on rapid-rotation schedules. The results also suggested that missing napping opportunities during night work, long nighttime working hours, and the delay of circadian rhythms are associated with the occurrence of SWD among shiftworking nurses on rapid-rotation schedules. (Author correspondence: yuinoue@tokyo-med.ac.jp)     

Metabolic Syndrome in Permanent Night Workers

Night and shift work might be risk factors for metabolic and cardiovascular disorders due to interference with diet, circadian metabolic rhythms, and lifestyle. The relationship between permanent night work and metabolic and cardiovascular risk factors was explored in a retrospective longitudinal study of workers employed in a large municipal enterprise in charge of street cleaning and domestic waste collection. All subjects who had worked night shifts between 1976 and 2007 as hand sweepers, motor sweepers, and delivery tricar drivers were compared with subjects who always worked the same jobs but on day shifts. From the periodical medical surveillance files, we identified 488 male workers who had been examined on average five times (minimum 2, maximum 14) during the study period, for a total of 2,328 medical examinations; 157 always had worked day shifts, 12 always the night shift, and 319 both (initially day and subsequently night shifts). Their age ranged from 22 to 62 yrs, and work experience varied from 1 to 28 yrs. Lifestyle habits (smoking, alcohol consumption), body mass index, serum glucose, total cholesterol, tryglicerides, hepatic enzymes, blood pressure, resting electrocardiogram, diabetes, coronary heart disease, hypertension, and related drugs were taken into consideration for the analysis. We used generalized estimating equations (GEE) models (exchangeable correlation matrix) to analyze the relationship between night work and health effects while accounting for within‐subject correlations and adjusting for study period, job, age, and lifestyle variables. As a whole, night workers smoked more and had significantly higher BMI, serum total cholesterol, and triglycerides than day workers. Both the inter‐individual comparison between day and night workers and the intra‐individual comparison among the workers, who were day workers at the beginning of their employment and later became night workers, showed a significant increase in BMI, total cholesterol, and tryglicerides associated with night work. No consistent effect was seen on fasting glucose, hepatic enzymes, and blood pressure, whereas a higher incidence of coronary heart disease was recorded in night workers.     

Self-Reported Health and Sleep Complaints Among Nursing Personnel Working Under 12 h Night and Day Shifts

This cross-sectional exploratory study involved health care workers of various skill types and levels. We tested the hypothesis that the prevalence of diseases, sleep complaints, and insufficient time for nonprofessional activities (family, leisure, and rest) are higher among night than day workers. Data collection was carried out in two public hospitals using questionnaires and other forms. Night work was explored as a risk factor, considering a night worker as one who had at least one night job on the occasion of the research. Data were assessed by a univariate analysis. The association between work schedule and the dependent variables—health conditions, sleep complaints, and insufficient time for nonprofessional activities—was evaluated through the estimation of the prevalence ratio, with a confidence interval of 95%. Two hundred and fifty-eight female nursing personnel participated; 41.5% were moonlighters, and only 20 worked a shift of less than 12 h in length. Reports of migraine and need of medical care the 2 weeks before the survey were more prevalent among day than night workers (PR = 0.71; CI = 0.55–0.92 and PR = 0.71; CI = 0.52–0.95, respectively). Migraine headaches occurred less frequently among night than day workers as confirmed by comparing the reports of the night workers and day workers whose work history was always day shifts (PR = 0.74; CI = 0.57–0.96). Reports of mild emotional disorders (mild depression, tension, anxiety, or insomnia) were less frequent among night (PR = 0.76; CI = 0.59–0.98) and ex-night workers (PR = 0.68; CI = 0.50–0.91) than day workers who never had worked a night job. The healthy worker effect does not seem to explain the results of the comparisons between day and night workers. The possible role of exposure by day workers to some risk factors, such as stress, was suggested as an explanation for these results. No significant difference was observed between night and day workers as to sleep complaints, a result that may have been influenced by the nature of the shift-work schedule (no successive night shifts) and possibly nap taking during the night shift. Moreover, the long work hours and moonlighting of the healthcare workers, which is common in Brazil, may have masked other possible differences between the day and night workers. Among night workers, a significant relation was found between years working nights (more than 10 yrs) and high cholesterol values (PR = 2.58; CI = 1.07–6.27), a result that deserves additional study. Working nights more than four times per 2-week span was related to complaints about insufficient time for children (PR = 1.96; CI = 1.38–2.78) and rest/leisure (PR = 1.54; CI = 1.20–1.99). These results can be related to the “social value of time,” as evenings and nights are when families usually spend time together. The complexity of the professional life and the consequent heterogeneity of the group of workers under shift-work schemes confound the results. More in-depth study of the questions raised here demands a more sophisticated epidemiological treatment and larger sample size.