TSH circadian secretions in aged men and effect of phosphatidylserine treatment

In 20 euthyroid aged men (from 65 to 85 years of age) no significant circadian periodicity of thyrotropin (TSH) secretion has been shown by the population mean cosinor method. At the end of a period of 30 days of hospitalization the cosinor evaluation of TSH secretion showed a restored highly significant (p less than 0.001) circadian rhythmicity in phosphatidylserine (PS) (400 mg/daily) treated group (10 aged subjects). By contrast, hospitalization seems to further deteriorate the periodicity of the hormone secretion in 10 placebo-treated subjects.     

Temperature change of the ripple structure in fully hydrated dimyristoylphosphatidylcholine/cholesterol multibilayers.

The ripple structure was studied as a function of temperature in fully hydrated dimyristoylphosphatidylcholine (DMPC)/cholesterol multibilayers using synchrotron x-ray small-angle diffraction and freeze-fracture electron microscopy. In the presence of cholesterol, the ripple structure appears below the pretransition temperature of pure DMPC multibilayers. In this temperature range the ripple periodicity is relatively large (25-30 nm) and rapidly decreases with increasing temperature. In this region, defined as region I, we observed coexistence of the P beta' phase and the L beta' phase. The large ripple periodicity is caused by the formation of the P beta' phase region in which cholesterol is concentrated and the L beta' phase region from which cholesterol is excluded. An increase in ripple periodicity also takes place in the narrow temperature range just below the main transition temperature. We define this temperature region as region III, where the ripple periodicity increases dramatically toward the main transition temperature. In region II, between regions I and III, the ripple periodicity decreases gradually with temperature. This behavior is quite similar to that of pure DMPC. Temperature-versus-ripple periodicity curves are parallel among pure DMPC and DMPCs with various cholesterol contents. We explain this behavior in terms of a model proposed by other workers.     

Both spillover and light absorption cross-section changes are involved in the regulation of excitation energy distribution between the two photosystems during state transitions in wheat leaf

Weak red light-induced changes in chlorophyll fluorescence parameters and in the distribution of PS I and PS II in thylakoid membranes were measured in wheat leaves to investigate effective ways to alter the excitation energy distribution between the two photosystems during state transition in vivo. Both the chlorophyll fluorescence parameter Fm/Fo and F685/F735, the ratio of fluorescence yields of the two photosystems at low temperature (77 K), decreased when wheat leaves were illuminated by weak red light of 640 nm, however, Fm/Fo decreased to its minimum in a shorter time than F685/F735. When Photosystem (PS II) thylakoid (BBY) membranes from adequately dark-adapted leaves (control) and from red light-illuminated leaves were subjected to SDS-polyacrylamide gel electrophoresis under mildly denaturing conditions, PS I was almost absent in the control, but was present in the membranes from the leaves preilluminated with the weak red light. In consonance with this result, the content of Cu, measured by means of the energy dispersive X-ray microanalysis (EDX), increased in the central region, but decreased in the margin of the grana stacks from the leaves preilluminated by the red light as compared with the control. It is therefore suggested that: (i) both spillover and absorption cross-section changes are effective ways to alter the excitation energy distribution between the two photosystems during state transitions in vivo, and the change in spillover has a quicker response to the unbalanced light absorption of the two photosystems than the change in light absorption cross-section, and (ii) the migration of PS I towards the central region of grana stack during the transition to state 2 leads to the enhancement of excitation energy spillover from PS II to PS I.     

低温弱光胁迫对日光温室栽培杏树光系统功能的影响

以温室栽培的金太阳杏为材料,测定了金太阳杏叶片光合速率(P_n)、光系统Ⅱ(PSⅡ)光下实际光化学效率(Φ_PSⅡ)、光化学猝灭系数(q_P)和开放的PSⅡ反应中心的激发能捕获效率(F_v^′/F_m^′), 探讨了低温弱光(7 ℃、200 μmol·m^-2·s^-1 PFD)对叶片光系统Ⅰ(PSⅠ)和PSⅡ的抑制作用.结果表明：温室栽培的金太阳杏叶光合作用的最适温度在25 ℃左右.光下7 ℃的低温可使叶片净光合速率(P_n)大幅下降,造成激发压(1-q_P)增大,进而引起光抑制.低温弱光条件使PSⅠ和PSⅡ功能受到破坏,与单纯低温胁迫(7 ℃,黑暗)处理相比,经低温、弱光(7 ℃, 200 μmol·m^-2·s^-1PFD)胁迫2 h后,PSⅠ活性下降了28.26%,而PSⅡ最大光化学效率（F_v/F_m）没有发生显著变化,表明低温弱光条件下PSⅠ比PSⅡ 更易发生光抑制.     

Some Effects of Temperature on the Nutation of Young Phaseolus Epicotyls

The effect of temperature on the periodicity of nutation inPhaseolus multiflours has been investigated using a mechanicalrecording system. Frequency of nutation was found to bear alinear relationship with temperature within the range studied(15–27 °C), the cycle length of the movement decreasingas temperature increased. Changes in periodicity follow changesin temperature with no appreciable delay.     

Temperature as a cue for the periodicity in feeding of Brachycentrus occidentalis (Insecta: Trichoptera)

Filtering behaviour of two groups of Brachycentrus occidentalis larvae exposed to a diel temperature cycle and a LD12:12 photoperiod, was observed for 5 days at 4-hr intervals. Both groups were then subjected to 5 days of continuous light; however, a diel temperature pattern was maintained for only one group. Behaviour of larvae showed a diel periodicity under the initial conditions that was quickly lost in continuous light and constant temperature. Under continuous light and daily fluctuating temperatures, larvae could maintain a diel periodicity. However, the amplitude of the periodicity was moderated.     

Ultrastructural differences between the myelin sheaths of peripheral nerve fibres and CNS white matter

Summary Electron microscopic studies of peripheral nerves and spinal cord white matter of adult mice, as prepared by the freeze-etching method, show distinct differences in the periodicity of the myelin lamellae as well as of the ultrastructural lamellar pattern. A periodicity of 185 Å is to be determined for peripheral myelin whereas it is 160 Å in the myelin of central origin.In contrast to the appearance in the peripheral myelin the lamellar structure in the central myelin sheath is less pronounced and tends towards a fundamental repeating unit of 80 Å.This work was supported by the Swiss National Foundation (Nr. 4065).     

Seasonal periodicity of aquatic fungi in tanks at Kurukshetra,India

The occurrence, distribution and seasonal periodicity of 49 species of aquatic fungi belonging to the orders Chytridiales, Lagenidiales, Blastocladiales, Saprolegniales and Peronosporales from two tanks of Kurukshetra, India, is described. Seasonal periodicity was found to be governed by temperature.     

Paradoxical sleep inhibition by central alpha-adrenoceptor stimulant clonidine antagonized by alpha-receptor blocker yohimbine.

In cats clonidine produces sedation and dose dependent inhibition of paradoxical sleep (PS). With 10 μg/kg PS is suppressed for ca. 8 hours. The α-adrenoceptor blocking drug yohimbine (2mg/kg) increases arousal and antagonizes the PS depressing effect of clonidine. This implies that the impact of clonidine on PS is due to its stimulating effect on central α-receptors. This interpretation, however, does not resolve the current controversy, whether noradrenaline (NA) is a positive or a negative factor in PS control. Stimulation of post-synaptic α-receptors may mimic the action of liberated NA, while stimulation of presynaptic receptors inhibits NA-liberation. Both clonidine and yohimbine are claimed to have a predominance of action on the presynaptic side. Definitive conclusions, however, would require more data about the central receptors, and the timing and balance of the agonist and antagonist actions envolved. Also central adrenaline receptors and interactions with the 5-HT system may complicate the situation.     

The influence of summer/winter conditions of temperature and irradiance on diel oscillations in photosynthesis by Fragilaria crotonensis

SUMMARY. 1. The common pennate diatom (Bacillaryiophyta) Fragilaria crotonensis Kitton showed strong periodicity in its photosynthesis -irradiance (P—I) relationship under summer conditions of high irradiance and temperature which damped progressively throughout the growth phase. Under winter conditions of low irradiance and temperature, weak periodicity was observed.
2. The amplitude of diel oscillations in photosynthesis as a function of irradiance under winter conditions showed only slight variation throughout the growth phase. Under summer conditions, however, amplitudes for both α and P_max were highest in the early exponential phase, declining progressively during growth.
3. These results indicate that the occurrence of periodicity is dependent, in part, on the growth phase of the cells and, in part, on environmental parameters of irradiance and temperature variations under simulated summer and winter conditions.     

Effect of High Temperature on Photosynthetic Electron Transport Activities of the Cyanobacterium Spirulina Platensis

The activities of photosystem 2 (PS2) and whole chain electron transport declined in high temperature treated cells at the room temperature beyond 35 °C, while photosystem 1 (PS1) showed increased activity. Thylakoid membrane studies did not exhibit increase in PS1 activity indicating that the enhancement of PS1 activity is due to permeability change of cell membranes. However, the electron transport activity measured from reduced duroquinone to methylviologen which involves intersystem electron transport was extremely sensitive to high temperature. The activity of PS2 at different irradiance, which was accompanied by alterations in absorption and fluorescence emission properties, indicated changes in the energy transfer processes within phycobilisomes. Thus high temperature has multiple target sites in photosynthetic electron transport system of Spirulina platensis.     

Differential action upon sleep states of ventrolateral and central areas of pontine tegmental field

In order to study oral pontine mechanisms of the sleep- wakefulness cycle (SWC), modifications in the total amount, frequency, and duration of episodes of wakefulness (W), drowsiness (D), slow sleep (SS) and paradoxical sleep (PS) together with modifications in the hourly distribution of both sleep states were analyzed in 15 adult cats. Three animals were used as sham-operated controls. Six of them, Group I, received unilateral lesions in ventral and lateral areas of the nucleus reticularis pontis oralis (RPO) and rostral nucleus reticularis pontis caudalis (RPC). The remaining 6 cats, Group II, had unilateral lesions in the central part of the same nuclei. After ventrolateral lesions (Group I) decrease of PS and SS occurred, but only PS changes reached statistically significant values; while, on the contrary, a significant increase of SS and PS followed central lesions (Group II). Hourly distribution analysis indicated that in Group I decrease of both sleep states took place mainly at night, while in Group II increase of both SS and PS occurred during day. These results suggest a complex and non- uniform influence of the pontine tegmental area on SWC mechanisms. Effects obtained after unilateral lesions, precisely located in ventral and lateral or central parts, point to the existence of two functionally distinct, although almost overlapping, systems, at this level.     

低温光抑制恢复过程中黄瓜叶片PSⅡ活性及其电子传递对PSⅠ的影响

以“津春4号”黄瓜为试材,通过测定黄瓜叶片叶绿素荧光快速诱导动力学曲线和对820 nm光的吸收曲线,结合叶绿素荧光淬灭分析,研究低温光胁迫(4℃,200 μmol·m-2·s-1)6 h后,黄瓜叶片在常温(25℃)不同光强(0、15、200μmol·m-2·s-1)下PS Ⅰ和PS Ⅱ活性的恢复,以及恢复过程中PS Ⅰ与PS Ⅱ的相互作用.结果表明:低温光胁迫6h后,PS Ⅰ和PS Ⅱ发生不同程度的光抑制.在常温恢复阶段,PS Ⅱ活性快速恢复且对光强不敏感;PS Ⅰ活性在弱光下(15 μmol·m-2·s-1)快速恢复,在较强光(200 μmol·m-2·s-1)下恢复较慢.在低温光抑制恢复过程中,常温下PS Ⅱ活性恢复较快可能导致PS Ⅱ向PS Ⅰ的线性电子传递过快,进而抑制PS Ⅰ的活性恢复.因此,在进行黄瓜抗冷性育种时,不应该仅追求较高的PS Ⅱ抗性和较快的PS Ⅱ恢复速度,还应该注意两个光系统活性的协调.在生产中,应当在低温逆境发生及其之后较长一段时间内采取措施降低叶表面光照强度,以利于对植株光合机构的保护和光合活性的恢复.     

Probing the effects of light and temperature on diurnal rhythms of phytosiderophore release in wheat

* The existing literature is ambiguous as to whether the diurnal pulse in phytosiderophore (PS) release in the Poaceae is mediated by light or temperature, or both. * Here, wheat (Triticum aestivum cv. Yecora Rojo) seedlings were grown in Fe-sufficient (pFe = 16.5) and Fe-deficient (pFe = 17.8) chelator-buffered nutrient solutions. Six different light/temperature regimes were tested over 8 d in paired growth chambers. * Phytosiderophore release patterns under a square-wave light regime were similar, irrespective of whether temperature was varied diurnally or held constant, but PS release was negligible when the light was removed. Release patterns of PS for Fe-deficient and Fe-sufficient plants grown under the square-wave vs ramped light and temperature regimes were similar in the corresponding Fe treatments. * Our results strongly support the notion that the diurnal pulse in PS release in the Poaceae is mainly mediated by changes in light rather than temperature. Our comparison of square-wave with more natural ramped light/temperature regimes suggests that the diurnal response patterns of PS release in wheat can be confidently studied using traditional square-wave regimes, and this is likely to be the case with other Poaceae as well.     

Effect of chromate on photosynthesis in Cr(VI)-resistant Chlorella

Chromate-resistant Chlorella spp. isolated from effluents of electroplating industry could grow in the presence of 30 μM K₂Cr₂O₇. Since photosynthesis is sensitive to oxidative stress, chromate toxicity to photosynthesis was examined in this algal isolate. Chromate [Cr(VI)] up to 100 μM was found to stimulate photosynthesis, while 90% inhibition was found, when the cells were incubated with 1 mM Cr(VI) for 4 h. Photosystem (PS) II was inhibited by 80% and PSI by 40% after such Cr(VI) treatment. Thermoluminescence studies on cells treated with 1 mM Cr(VI) for 4 h showed that S₂Q_A ^? recombination peak (Q) was shifted to higher temperature, whereas S₂/S₃Q_B ^? recombination peak (B) was shifted to lower temperature. These shifts indicated alga stress response in order to overcome an excitation stress resulting from the inhibition of photosynthesis by Cr(VI). The nontreated Chlorella cells kept in the dark showed periodicity of four for the Q peak (4–8°C) and B peak (34–38°C) after exposure to series of single, turnover, saturating flashes. This periodicity was lost in Cr(VI)-treated cells. Higher concentrations of Cr(VI) inhibited mainly the electron flow in the electron transport chain, inactivated oxygen evolving complex, and affected also Calvin cycle enzymes in the Cr(VI)-resistant isolates of Chlorella.     

Large temperature plunges recorded by data loggers at different depths on an Indian Ocean atoll: comparison with satellite data and relevance to coral refuges

Seawater temperature was recorded at two-hourly intervals for two years (March 2006-March 2008) by six data loggers in Diego Garcia atoll, central Indian Ocean. Loggers were substrate mounted, in two transects of 5, 15 and 25 m depth on a seaward reef and in a lagoonal pass. During the season of mixed but predominantly northwest winds, regular plunges of temperature of 5–7°C occurred with a periodicity of 1–4 days. This partly coincided with the period of greatest annual warming. Temperature fluctuations increased with increasing depth. Temperature traces are compared with HadISST1 and AVHRR satellite-derived temperature data which do not capture the deeper water temperature plunges. Reasons for the regular temperature plunges appear to include both tidal cycles and unidentified, internal waves. This is important for issues of coral refuges, complicating use of satellite-derived temperature data for planning optimal coral reef conservation areas.     

Changes of phosphatidylserine distribution in human red blood cells during the process of loading sugars

The plasma membrane of red blood cells permits sugars to be loaded into the cytoplasm simply by incubation in a suitable buffer solution containing the sugar. This may provide some hope for the freeze-drying of human red blood cells. However, the effect of the loading process on red blood cells has not been fully investigated. The exposure of phosphatidylserine (PS) on the surface of the cell can be recognized by macrophages and result in shortened circulation in vivo. This study evaluates the effects of the concentration, the incubation time, and the temperature of exposure of human red blood cells to extracellular trehalose or glucose. Exposure of PS was demonstrated by annexin V labeling. It was shown that the efficiency of loading of glucose was significantly greater than that of trehalose. The loading efficiency of both sugars increased with increase in extracellular sugar concentration, prolongation of incubation time, and increase of incubation temperature. The percentages of cells with exposed PS and of damaged cells were dependent on the extracellular sugar concentration, the incubation time, and the temperature. With an extracellular glucose concentration of 0.8M, the percentage of cells with exposed PS was more than 80% and significantly higher than that of red blood cells loaded with trehalose (approximate 20%, P<0.01). As the incubation time was prolonged, the percentage of PS exposure and of damaged cells also increased. After incubation for 5h, the percentage of red cells with exposed PS following loading with glucose was more than 80% and significantly higher than that of cells loaded with trehalose (40%, P<0.01). In addition, the incubation temperature had a major effect on PS exposure. The percentage of cells with PS exposure and the proportion of damaged cells increased with increase of incubation temperature. At 37 degrees C, the percentage of cells with exposed PS and of damaged cells after loading with glucose was more than 80% and significantly higher than that of cells loaded with trehalose (P<0.01). However, when the temperature was below 25 degrees C, the percentage of cells with exposed PS and of damaged cells after loading with glucose or trehalose were both less than 10%. In conclusion, the loading efficiency for glucose was higher than that for trehalose, but the lesser effect of trehalose on exposure of PS suggests that it can maintain the asymmetrical distribution of membrane phospholipids and the intracellular trehalose can increase the osmotic tolerance of cells.     

Central administration of phosphatidylserine attenuates isolation stress-induced behavior in chicks

The present study investigated whether centrally administered phosphatidylserine (PS) could modify the behavior of chicks under isolation-induced stress. Isolation stress-induced vocalization and spontaneous activity for 10 min, which were attenuated by intracerebroventricular (i.c.v.) injection of PS. The effect of PS was compared with other phospholipids or L-serine, a constituent of PS. Phosphatidylcholine (PC) had no effect on these behavior, but phosphatidylethanolamine (PE) significantly increased vocalizations and spontaneous activity compared with PS. L-Serine similarly decreased isolation-induced vocalizations and spontaneous activity. To clarify the mechanism by which central PS attenuates isolation-induced stress behavior, the contribution of the acetylcholine (ACh) receptor (AChR) was also investigated. PS was co-injected i.c.v. with the muscarinic AChR (M-AChR) antagonist scopolamine or the nicotinic AChR (N-AChR) antagonist hexamethonium. The suppression of vocalizations and spontaneous activity by PS was partially attenuated by scopolamine, but not hexamethonium. These findings indicate that isolation-induced stress behavior are attenuated by PS, acting partially through the M-AChR.     

High-resolution mapping reveals topologically distinct cellular pools of phosphatidylserine

Phosphatidylserine (PS) plays a central role in cell signaling and in the biosynthesis of other lipids. To date, however, the subcellular distribution and transmembrane topology of this crucial phospholipid remain ill-defined. We transfected cells with a GFP-tagged C2 domain of lactadherin to detect by light and electron microscopy PS exposed on the cytosolic leaflet of the plasmalemma and organellar membranes. Cytoplasmically exposed PS was found to be clustered on the plasma membrane, and to be associated with caveolae, the trans-Golgi network, and endocytic organelles including intraluminal vesicles of multivesicular endosomes. This labeling pattern was compared with the total cellular distribution of PS as visualized using a novel on-section technique. These complementary methods revealed PS in the interior of the ER, Golgi complex, and mitochondria. These results indicate that PS in the lumenal monolayer of the ER and Golgi complex becomes exposed cytosolically at the trans-Golgi network. Transmembrane flipping of PS may contribute to the exit of cargo from the Golgi complex.     

The cercarial emergence of Schistosoma japonicum from Oncomelania quadrasi under outdoor conditions in the Philippines

The cercarial emergence of Schistosoma japonicum from Oncomelania quadrasi was observed under outdoor conditions in Leyte, Philippines. Nocturnal periodicity of the emergence within 24 hours was recognized. Peak emergence usually occurs between 18:00 and 20:00 and occasionally between 8:00 and 10:00. The peaks were usually synchronized with a sudden lowering of water temperature and light intensity and occasionally with their increase. As the nocturnal periodicity of the emergence was observed in the dark and outdoors, it was suggested that emergence might be dependent on temperature, which is secondarily influenced by photoperiodicity and light intensity.