The effect of season and light intensity on the core interthreshold zone

The hypothesis tested in the present study is a seasonal difference in the core interthreshold zone (CIZ), as we suggested in an earlier study that individual awareness of heat may change the CIZ due to thermoregulatory behavior. A series of human experiments were carried out in a climatic chamber in January and August of 2009 and January of 2010. The air temperature in the chamber was controlled at 20-24°C. Subjects wore a water-perfused suit that was perfused with 25°C water at a rate of 600 cc/min. They exercised on an ergometer at 50% of their maximum work rate for 10-15 min until their sweating rate increased and then remained seated without exercise until oxygen uptake increased. Subjects' rectal temperature and skin temperatures at four sites were monitored by thermistors. The sweating rate was measured at the forehead with a sweat rate monitor (SKD 4000, Skinos Co.). Oxygen uptake was monitored with a gas analyzer (Respiromonitor RM-300i, Minato Med. Science Co.). In the 2009 winter experiment, 5 male subjects were exposed to lighting of 36 cd/m(2)/1,050 lx, and in the 2009 summer and 2010 winter experiments, 10 male subjects were exposed to lighting of 18 cd/m2/510 lx. The results showed that the CIZ of 0.69±0.29°C (n=22, data from 2005-2007 experiments) at 36 cd/m(2) and that of 0.37±0.17°C (n=10) at 18 cd/m(2) in summer were greater than the CIZ of 0.37±0.13°C (n=5) at 36 cd/m(2) and that of 0.18±0.17°C (n=10) at 18 cd/m(2) in winter, and thus demonstrated a seasonal difference in the CIZ as well as an effect of lighting conditions on the CIZ.     

Temperatures of skin, subcutaneous tissue, muscle and core in resting men in cold, comfortable and hot conditions

To examine the core-shell model of temperature distribution and the possible role of subcutaneous temperature in heat regulation, comprehensive temperature measurements were made on six nude resting men exposed for 2-3 h to comfort (27 degrees C), cold (15 degrees C) and heat (45 degrees C). Cold produced strong shivering and heat caused heavy sweating. Temperatures were recorded every 10 min from: esophagus, rectum and auditory canal; back muscle and thigh muscle at 20 mm and 40 mm depths; 6 subcutaneous sites; and 16 skin sites. Average temperatures at these 29 sites were tabulated at the ends of comfort, hot and cold and the onsets of sweating and shivering. Body temperature changes were slow to develop, the skin temperatures being fastest, and successively deeper tissues progressively slower. There was occasional after-drop and after-rise. The data were consistent with the core-shell concept. The temperature gradient from subcutaneous tissue to skin, which differed substantially with comfort, the onset of shivering and the onset of sweating, could serve as a regulatory signal. The data are now in computer format and may be of interest to biothermal modelers.     

Thermoregulatory responses in humans during exercise after exposure to two different light intensities

The effects after exposure to two different light intensities (dim, 50 lx and bright, 5000 lx) on thermoregulatory responses during exercise in a climatic chamber (27 degrees C, 60% relative humidity) were studied in nine untrained female subjects, aged 19-22 years. The subjects were in either the dim or bright light intensities from 0600 hours to 1200 hours. They were then instructed to exercise on a cycle ergometer at an intensity of 60% maximal oxygen uptake from 1200 hours to 1300 hours in a light intensity of 500 Ix. The main results can be summarized as follows. Firstly, exercise-induced increases of core temperature were significantly smaller, after exposure to the bright than after the dim light intensities, although both tests were performed in the same light intensity. Secondly, body mass loss after exercise was significantly greater after exposure to the bright light intensity. Thirdly, an increase in salivary lactic acid during exercise was significantly lower after the bright intensity. Fourthly although the salivary melatonin level was not different between the two light intensities both before and after the exercise, it increased significantly during exercise only after the bright intensity. These results are discussed in terms of the establishment of a lower set-point in the core temperature after exposure to a bright light intensity.     

The effects of blue and red light on Acetabularia mediterranea after long exposure to darkness

After Acetabularia mediterranea cells were kept in darkness for 2–8 weeks, all the cellular processes were arrested and the algae did not grow. In particular, the transcellular electrical potential (V_AB) decreased to almost zero and cytoplasmic streaming was arrested. Upon illumination with continous blue light (BL), the first events were (as with white light (WL)), immediate increase in V_AB and movements of water, followed, after a lag period of 1–3 min, by transient recovery of cytoplasmic streaming which lasted about 16 min. After 10 min (earlier than in WL), the frequency of the spontaneous action potentials increased much more than in WL. Then, after 1.5–4 hr during which V_AB often decreased to zero while the cytoplasmic movements stopped, both activities resumed with diurnal oscillations. BL stimulated (as WL) rRNA synthesis, migration of rRNA from nucleus towards apex and cell growth. Upon illumination with red light (RL), V_AB also increased, but water movements were much less pronounced than in BL. The transient streaming phase was shorter. The spontaneous action potentials increased in frequency much later (several hr) and much less than in BL or WL. V_AB did not decreased at any time and was maintained at particularly high values. Cytoplasmic streaming resumed, but showed very attenuated or no rhythm. rRNA synthesis and migration remained low. Cell growth did not resume during the experiments. By comparing our results with those of other studies relating to growth, morphogenesis and photosynthesis, we suggest that BL and RL could affect all these processes by differentially modifying the cytoplasmic concentrations of ions which may influence the functions of the cytoskeleton.     

Intramuscular temperatures during exercise in the heat following pre-cooling and pre-heating

Pre-cooling improves heat tolerance and time to exhaustion in the heat. We tested the possibility that reduced tissue temperatures may explain this phenomenon, using three whole-body treatments: pre-cooling, thermoneutral (control) and pre-heating. Pre-cooling reduced muscle temperature (T_m) by 6.3 °C while pre-heating increased T_m 3.4 °C, relative to control. Despite this offset, T_m climbed towards a common asymptote, with pre-cooling offering no thermal protection beyond 40 min. Following pre-cooling, exercising oesophageal temperature (T_es) initially increased at 0.09 °C min⁻¹, being significantly faster than control (0.05 °C min⁻¹) and pre-heated conditions (0.03 °C min⁻¹). Pre-cooling lowered the sweat threshold and also resulted in a reduced cardiac frequency across the exercise-heat exposure. Our observations do not support the hypothesis that pre-cooling reduces T_m at the end of an exercise-heat exposure, thereby delaying the development of fatigue.     

红蓝光调控茉莉开花的转录组分析

茉莉花是多年生常绿灌木植物,因其香气芬芳怡人,常被作为天然香料的原材料。本研究通过红光和蓝光分别处理茉莉植株,以白光模拟日光作为对照,观察茉莉植株开花早晚情况,结果表明,红光处理可促使茉莉花提前开花且增加花蕾数量,而蓝光延迟茉莉开花但花蕾数量减少,且各组之间花蕾数量差异显著。采用Illumina Hiseq/Miseq 2000高通量测序技术对红光组、蓝光组及白光组的顶芽部分进行转录组测序,共得到2 452 457条单基因簇(Unigene),其中1 760 723个Unigenes注释到GO、COG、KEGG、KOG、NR、Pfam、Swiss-Prot、NOG数据库。差异表达基因分析显示,对照组vs红光组共获得894个DEGs,对照组vs蓝光组共获得2 690个DEGs,红光组vs蓝光组共获得3 828个DEGs,共有的DEGs有72个。KEGG富集分析显示对照组vs红光组与对照组vs蓝光组共有的显著富集通路包括次生代谢物生物合成、苯丙素生物合成、吲哚生物碱生物合成、光合作用、植物激素信号传导和植物-病原体相互作用等,并从中筛选出24条差异表达基因,采用荧光定量PCR技术检测其表达...     

Habituation of the metabolic and ventilatory responses to cold-water immersion in humans

An experiment was undertaken to answer long-standing questions concerning the nature of metabolic habituation in repeatedly cooled humans. It was hypothesised that repeated skin and deep-body cooling would produce such a habituation that would be specific to the magnitude of the cooling experienced, and that skin cooling alone would dampen the cold-shock but not the metabolic response to cold-water immersion. Twenty-one male participants were divided into three groups, each of which completed two experimental immersions in 12 °C water, lasting until either rectal temperature fell to 35 °C or 90 min had elapsed. Between these two immersions, the control group avoided cold exposures, whilst two experimental groups completed five additional immersions (12 °C). One experimental group repeatedly immersed for 45 min in average, resulting in deep-body (1.18 °C) and skin temperature reductions. The immersions in the second experimental group were designed to result only in skin temperature reductions, and lasted only 5 min. Only the deep-body cooling group displayed a significantly blunted metabolic response during the second experimental immersion until rectal temperature decreased by 1.18 °C, but no habituation was observed when they were cooled further. The skin cooling group showed a significant habituation in the ventilatory response during the initial 5 min of the second experimental immersion, but no alteration in the metabolic response. It is concluded that repeated falls of skin and deep-body temperature can habituate the metabolic response, which shows tissue temperature specificity. However, skin temperature cooling only will lower the cold-shock response, but appears not to elicit an alteration in the metabolic response.     

Physiological significance of 3-h bright and dim light exposure prior to taking a bath for core and forehead skin temperatures and heart rate during 1-h bathing of 38.5°C

1. The study investigated the effect of exposure to 3-h bright light (2500 lx) or dim light (200 lx) just prior to taking a hot bath upon thermophysiological responses during the 1-h bath (at 38.5°C water temperature). 2. Core and forehead skin temperature increases during the bath were significantly lower after bright than after dim light exposure. 3. Heart rate during the bath was significantly lower after exposure to bright light than dim light. 4. These results are discussed in terms of a reduced set-point of core temperature due to a probable higher secretion of melatonin under the bright light condition.     

Acute dim light at night increases body mass,alters metabolism,and shifts core body temperature circadian rhythms

The circadian system is primarily entrained by the ambient light environment and is fundamentally linked to metabolism. Mounting evidence suggests a causal relationship among aberrant light exposure, shift work, and metabolic disease. Previous research has demonstrated deleterious metabolic phenotypes elicited by chronic (>4 weeks) exposure to dim light at night (DLAN) (～5?lux). However, the metabolic effects of short-term (<2 weeks) exposure to DLAN are unspecified. We hypothesized that metabolic alterations would arise in response to just 2 weeks of DLAN. Specifically, we predicted that mice exposed to dim light would gain more body mass, alter whole body metabolism, and display altered body temperature (T_b) and activity rhythms compared to mice maintained in dark nights. Our data largely support these predictions; DLAN mice gained significantly more mass, reduced whole body energy expenditure, increased carbohydrate over fat oxidation, and altered temperature circadian rhythms. Importantly, these alterations occurred despite similar activity locomotor levels (and rhythms) and total food intake between groups. Peripheral clocks are potently entrained by body temperature rhythms, and the deregulation of body temperature we observed may contribute to metabolic problems due to “internal desynchrony” between the central circadian oscillator and temperature sensitive peripheral clocks. We conclude that even relatively short-term exposure to low levels of nighttime light can influence metabolism to increase mass gain.     

Fluorescence in blue light (FLU) is involved in inactivation and localization of glutamyl‐tRNA reductase during light exposure

Fluorescent in blue light (FLU) is a negative regulator involved in dark repression of 5‐aminolevulinic acid (ALA) synthesis and interacts with glutamyl‐tRNA reductase (GluTR), the rate‐limiting enzyme of tetrapyrrole biosynthesis. In this study, we investigated FLU‘s regulatory function in light‐exposed FLU‐overexpressing (FLUOE) Arabidopsis lines and under fluctuating light intensities in wild‐type (WT) and flu seedlings. FLUOE lines suppress ALA synthesis in the light, resulting in reduced chlorophyll content, but more strongly in low and high light than in medium growth light. This situation indicates that FLU's impact on chlorophyll biosynthesis depends on light intensity. FLU overexpressors contain strongly increased amounts of mainly membrane‐associated GluTR. These findings correlate with FLU‐dependent localization of GluTR to plastidic membranes and concomitant inhibition, such that only the soluble GluTR fraction is active. The overaccumulation of membrane‐associated GluTR indicates that FLU binding enhances GluTR stability. Interestingly, under fluctuating light, the leaves of flu mutants contain less chlorophyll compared with WT and become necrotic. We propose that FLU is basically required for fine‐tuned ALA synthesis. FLU not only mediates dark repression of ALA synthesis, but functions also to control balanced ALA synthesis under variable light intensities to ensure the adequate supply of chlorophyll.     

A comparison of sweating responses during exercise and recovery in terms of sweating rate and body temperature

Based on the hypothesis that the relation between sweating rate and body temperature should be different during exercise and rest after exercise, we compared the sweating response during exercise and recovery at a similar body temperature. Healthy male subjects performed submaximal exercise (Experiment 1) and maximal exercise (Experiment 2) in a room at 27° C and 35% relative humidity. During exercise and recovery of 20 min after exercise, esophageal temperature (Tes), mean skin temperature, mean body temperature ( ), chest sweating rate ( ), and the frequency of sweat expulsion (F _SW) were measured. In both experiments, andF _SW were clearly higher during exercise than recovery at a similar body temperature (Tes, ). was similar during exercise and recovery, or a little less during the former, at a similarF _SW. It is concluded that the sweating rate during exercise is greater than that during recovery at the same body temperature, due to greater central sudomotor activity during exercise. The difference between the two values is thought to be related to non-thermal factors and the rate of change in mean skin temperature.     

Effects of a single short exposure to blue light on cognitive performance

The aim of the present study is to explore the effects of a single short one-minute exposure to blue light on cognitive performance. For this purpose, 32 young adults (16 females, mean age 24.06 ± 1.88 years) took part in a within-subjects research design, under two conditions: blue light and no light. Under both conditions, they performed the lexical decision task (LDT) in order to assess the degree of automatic activation of semantic memory through an embedded semantic priming (reaction times to prime – reaction times to target), together with the Attention Network Test (ANT) to assess the efficiency of the alerting, executive and orienting networks. During the LDT, a significantly stronger semantic priming under the blue light condition compared to no light was observed, while during the ANT a significant difference in orienting network efficiency between conditions was observed. The present data appear to highlight that even a single short exposure to blue light has an effect on cognitive performance in young adults.     

Patterns and dynamics of rest-phase hypothermia in wild and captive blue tits during winter

We evaluated biotic and abiotic predictors of rest-phase hypothermia in wintering blue tits (Cyanistes caeruleus) and also assessed how food availability influences nightly thermoregulation. On any given night, captive blue tits (with unrestricted access to food) remained largely homeothermic, whereas free-ranging birds decreased their body temperature (T _b) by about 5°C. This was not an effect of increased stress in the aviary as we found no difference in circulating corticosterone between groups. Nocturnal T _b in free-ranging birds varied with ambient temperature, date and time. Conversely, T _b in captive birds could not be explained by climatic or temporal factors, but differed slightly between the sexes. We argue that the degree of hypothermia is controlled predominantly by birds’ ability to obtain sufficient energy reserves during the day. However, environmental factors became increasingly important for thermoregulation when resources were limited. Moreover, as birds did not enter hypothermia in captivity when food was abundant, we suggest that this strategy has associated costs and hence is avoided whenever resource levels permit.     

Exposing broiler eggs to green,red and white light during incubation

Previous work has shown that exposing broiler eggs to white light during incubation can improve hatchability and post-hatch animal welfare. It was hypothesized that due to how different wavelengths of light can affect avian physiology differently, and how pigmented eggshells filter light that different monochromatic wavelengths would have differential effects on hatchability and post-hatch animal welfare indicators. To determine, we incubated chicken eggs (n=6912) under either no light (dark), green light, red light or white light; the light level was 250 lux. White and red light were observed to increase hatch of fertile (P<0.05) over dark and green light incubated eggs. White, red and green light exposure during incubation improved (P<0.05) the proportion of non-defect chicks over dark incubated eggs. Post-hatch 45-day weight and feed conversion was not affected by light exposure of any wavelength (P>0.05). Fear response of during isolation and tonic immobility was reduced (P<0.05) in broilers incubated under white or red light when compared with either green or dark broilers. Broilers incubated with white or red light had lower (P<0.05) composite asymmetry scores and higher (P<0.05) humoral immunity titers than dark incubated broilers, however, green light broilers did not differ (P>0.05) from dark incubated broilers. All light incubated broilers had lower (P<0.05) plasma corticosterone and higher (P<0.05) plasma serotonin concentrations than dark incubated broilers. These results indicate that white light and red light that is a component of it are possibly the key spectrum to improving hatchability and lower fear and stress susceptibility, whereas green light is not as effective. Incubating broiler eggs under these spectrums could be used to improve hatchery efficiency and post-hatch animal welfare at the same time.     

Effects of blue and red light on unrolling of rice leaves

Unrolling of the second leaf of 8-day-old rice (Oryza sativa L.) seedlings was promoted by weak blue light (B), but not by red light (R). The effect of B was counteracted by irradiation with R just before or after the B. The counteracting effect of R was reversed by subsequent irradiation with far-red light but not by B, even if B was applied for 10 h. The B was effective when the region 0.5–2 cm from the tip of the leaf was irradiated. These results indicate that in rice photoreceptors for blue light located in the region 0.5–2 cm from the tip of the leaf play a key role in leaf unrolling and that a B-absorbing pigment and phytochrome participate in leaf unrolling in a closely related manner.Abbreviations B blue light - R red light - FR far-red light - W white light - D dark This work was presented at the Annual Meeting of the Japanese Society of Plant Physiologists on April 4, 1978, in Hiroshima     

Desensitization by red and blue light of phototropism in maize coleoptiles

The effects of pretreatments with red and blue light (RL, BL) on the fluence-response curve for the phototropism induced by a BL pulse (first positive curvature) were investigated with darkadapted maize (Zea mays L.) coleoptiles. A pulse of RL, giving a fluence sufficient to saturate phytochrome-mediated responses in this material, shifted the bell-shaped phototropic fluence-response curve to higher fluences and increased its peak height. A pulse of high-fluence BL given immediately prior to this RL treatment temporarily suppressed the phototropic fluence-response curve, and shifted the curve to higher fluences than induced by RL alone. The shift by BL progressed rapidly compared to that by RL. The results indicate (1) that first positive curvature is desensitized by both phytochrome and a BL system, (2) that desensitization by BL occurs with respect to both the maximal response and the quantum efficiency, and (3) that the desensitization responses mediated by phytochrome and the BL system can be induced simultaneously but develop following different kinetics. It is suggested that theses desensitization responses contribute to the induction of second positive curvature, a response induced by prolonged irradiation.Abbreviations BL blue light - RL red light CIW-DPB Publication No. 1001     

Cheek skin temperature and thermal resistance in active and inactive individuals during exposure to cold wind

1. The present study examined the effect of the thermal state of the body (as reflected by rectal temperature) on cheek skin temperature and thermal resistance in active and inactive subjects.

2. Active subjects were exposed to a 30 min conditioning period (CP) (0 °C air with a 2 m/s wind), followed immediately by a 30 min experimental period (EP) (0 °C with a 5 m/s wind). Inactive subjects were exposed to a 30 min CP (22 °C air with no wind), followed immediately by a 45 min EP (0 °C air with a 4.5 m/s wind). The CP period was used to establish a core temperature difference between the active and inactive subjects prior to the start of EP. The 0 °C exposure was replaced with a −10 °C ambient air exposure and the experiment was repeated on a separate day. Subjects were comfortably dressed for each ambient condition.

3. Cheek skin temperature was not significantly higher in active subjects when compared to inactive subjects, but thermal resistance was higher in active subjects.

4. Cheek skin temperature and thermal resistance both decreased as ambient temperature decreased from 0 to −10 °C. The lower cheek thermal resistance at −10 °C may have been due to a greater cheek blood flow as a result of cold-induced vasodilation.

Quantitative correlation of peripheral and intrinsic core polypeptides of photosystem II with photosynthetic electron-transport activity ofAcetabularia mediterranea in red and blue light

The high photosynthetic activity (O₂ production and CO₂ consumption) ofAcetabularia mediterranea Lamour. (=A. acetabulum (L.) Silva) characteristic of cells cultured in white light decreases slowly when cells are kept in continuous red light, and is less than 20% of the original activity after three weeks. Subsequent blue irradiation restores the original activity completely within 3–5 d. The polypeptide composition of the thylakoids from cells grown in either red or blue light and after transfer from red to blue light was analyzed mainly with regards to photosystem II (PSII). The P700-containing reaction-centre complex of photosystem I, CPI, showed only minor quantitative alterations as a consequence of the growth-light quality, which correlated well with the activity of photosystem I under these conditions. In PSII, no drastic changes occurred in the quantity of the reaction-centre components D1 (herbicide-binding polypeptide) and D2, as determined by immunoblots. Likewise, the proteins associated with the water-splitting apparatus did not change detectably in thylakoids from red- or blue-light-treated cells (the 16-kDa component could not be found inAcetabularia thylakoids). The level of the major light-harvesting complex was completely unaffected by the light quality. In contrast, the quantities of the chlorophyll a-protein complexes of the core antenna, CP43 and CP47 (and probably CP29), changed, with kinetics similar to those of total photosynthetic activity. We postulate that the function of the PSII antenna became increasingly impaired in the absence of blue light (i.e. in red light), while blue light had a restoring effect. The peripheral antenna, comprising the light-harvesting complexes, is probably functionally connected with the reaction-centre chlorophylls via the core antenna chlorophyll-protein complexes (CP43, CP47 and probably CP29). A deficiency of these complexes would lead to uncoupling of antenna and reaction centre in the majority of PSII complexes after long periods of red-light treatment.     

Relative effectiveness and interaction of ultraviolet-B, red and blue light in anthocyanin synthesis of apple fruit

The effect of light on anthocyanin production in apple ( Malus pumila Mill. cv. Jonathan) skin disks was investigated, with prolonged irradiation from different light sources. High fluence rates of white light provided from a xenon lamp were unable to produce large amounts of anthocyanin, and anthocyanin production became saturated at about 30 W m⁻². When UV-B light, provided by a fluorescent lamp which had an emission peak at 312 nm, was combined with the white light, anthocyanin production was synergistically stimulated and increased up to the highest fluence rates of white light tested (44 W m⁻²). This UV-B light was more effective than red and blue light provided from fluorescent lamps, but anthocyanin production became saturated at about 1.7 W m⁻². However, simultaneous irradiation with red and UV-B light had a synergistic effect. UV-B light was also effective in increasing anthocyanin production in whole fruit. Therefore this synergism seemed to have an important role in the development of the desirable red skin color under field light conditions. The results of aminoethoxyvinylglycine treatment suggested that ethylene was not involved in the stimulative effect of UV-B light.     

Assembly of LH2 light-harvesting complexes in Rhodopseudomonas palustris cells illuminated by blue and red light

We investigated the formation of the B800-850 complex in cells of the bacterium Rhodopseudomonas palustris AB illuminated by red and blue light under anaerobic growth conditions. Under red illumination, the B800-850 complex was assembled with a reduced absorption band at 850 nm. The results of re-electrophoresis of the B800-850 complex and oxidation in the presence of potassium iridate suggest its heterogeneity. It may be a mixture of two complexes (B800 and B800-850). The B800-850 complex lacks the capacity for conformational transitions if assembled under blue illumination. Accordingly, the light-harvesting complex assembled in the blue light contains polypeptides that are not synthesized under normal conditions or at increased or decreased light intensities. The mechanism of regulation of the synthesis of the polypeptides of light-harvesting the B800-850 complex and its dependence on the spectral composition of the light is discussed.