The influence of long-term estrogen treatments on daily plasma prolactin levels in ovariectomized rats

Prolactin levels were determined in the plasma of female rats from 4 to 54 days after ovariectomy or ovariectomy and treatment with a long acting polymer of estradiol, polyestradiol phosphate (PEP), or Silastic implants of crystalline estradiol-17β. Blood samples were withdrawn from indwelling aortic catheters in the morning (0900–1100) and afternoon (1500–1700). Both methods of estrogen delivery elevated plasma prolactin in the morning and afternoon compared to ovariectomized controls. However, the increases in the afternoon were significantly greater than those in the morning. The difference from ovariectomized controls and the morning-afternoon differences were maintained for 25–26 days in the polyestradiol phosphate-treated group whereas those differences in the group receiving the implants of estradiol were significant for the entire length of the experiment (54 days). In addition, there were periodic fluctuations in the morning and afternoon levels of prolactin in the estradiol implanted animals. It is suggested that the plasma prolactin response to estrogen varies with time of day, time after administration of estrogen and with the method of estrogen delivery.     

Importance of sandy bottoms in coral reefs to the oscillation of daily rhythms in the tropical wrasse Halichoeres trimaculatus

Most wrasse species swim during the day and bury themselves in the sandy bottoms of shallow reefs at night. This study aimed to evaluate the importance of sandy bottoms to the day-active/night-inactive rhythmicity of the tropical wrasse Halichoeres trimaculatus. Actogram analysis revealed that fish were active during the photophase and inactive during the scotophase in aquariums with both sandy and bare bottoms. When fish were kept in aquariums with bare bottoms, rhythmicity was maintained under constant dark conditions (DD) but became obscured under constant light conditions (LL), suggesting that a day-active/night-inactive rhythmicity is regulated by the circadian system. Robust fluctuations in Period1 (wPer1) and Period2 (wPer2) expression were observed in the pectoral fin tissue under light–dark conditions (LD). Similar fluctuations in wPer1 expression persisted under DD. When fish were kept under LD conditions for 7 days and then DD for 20 days, the emergence of fish from the sandy bottom was delayed gradually. At the same time, the peak time of wPer1 expression under DD was retarded from 06:00 to 10:00. Although wPer2 expression was dampened under DD, it increased after exposing fish to light. These results suggest that wPer1 and wPer2 are differentially involved in the day-active/night-inactive rhythmicity, and that blocking light with a sandy bed at night and exposing fish to light during emergence in the morning play important roles in maintaining consistent activities in wrasse species.     

COP1 re‐accumulates in the nucleus under shade

Shade‐avoider plants typically respond to shade‐light signals by increasing the rate of stem growth. CONSTITTUTIVE PHOTOMORPHOGENESIS 1 (COP1) is an E3 ligase involved in the ubiquitin labelling of proteins targeted for degradation. In dark‐grown seedlings, COP1 accumulates in the nucleus and light exposure causes COP1 migration to the cytosol. Here, we show that in Arabidopsis thaliana, COP1 accumulates in the nucleus under natural or simulated shade, despite the presence of far‐red light. In plants grown under white light, the transfer to shade‐light conditions triggers an unexpectedly rapid re‐accumulation of COP1 in the nucleus. The partial simulation of shade by lowering either blue or red light levels (maintaining far‐red light) caused COP1 nuclear re‐accumulation. Hypocotyl growth of wild‐type seedlings is more sensitive to afternoon shade than to morning shade. A residual response to shade was observed in the cop1 mutant background, but these seedlings showed inverted sensitivity as they responded to morning shade and not to afternoon shade. COP1 overexpression exaggerated the wild‐type pattern by enhancing afternoon sensitivity and making morning shade inhibitory of growth. COP1 nuclear re‐accumulation also responded more strongly to afternoon shade than to morning shade. These results are consistent with a signalling role of COP1 in shade avoidance. We propose a function of COP1 in setting the daily patterns of sensitivity to shade in the fluctuating light environments of plant canopies.     

Effects of seed hydropriming in presence of exogenous proline on chilling injury limitation in <Emphasis Type="Italic">Vigna radiata</Emphasis> L. seedlings

Three-day-old seedlings (t ₀ stage) of Vigna radiata (L.) Wilczek obtained from seeds hydroprimed (H) and hydroprimed with proline (HPro) were examined. H and HPro slightly improved mung bean seed germination and seedlings growth at 5°C. The best growth was observed in the seedlings obtain from HPro5 (5 mM) seeds in comparison with the seedlings obtained from the control-non-primed seeds and H seeds. Exposure of mung bean seedlings grown from non-primed seeds to chilling for 4 days induced chilling injury: membrane lipid peroxidation, decrease in endogenous proline level and inhibition of growth of roots and hypocotyls. The seedlings obtain from HPro seeds grew better during the time of chilling and after rewarming at 25°C. The possible role of HPro in chilling injury limitation is discussed.     

Diurnal Variations in Cycling Kinematics

Physiological and biomechanical constraints as well as their fluctuations throughout the day must be considered when studying determinant factors in the preferred pedaling rate of elite cyclists. The aim of this study was to monitor the diurnal variation of spontaneous pedaling rate and movement kinematics over the crank cycle. Twelve male competitive cyclists performed a submaximal exercise on a cycle ergometer for 15 min at 50% of their W_max. Two test sessions were performed at 06:00 and 18:00 h on two separate days to assess diurnal variation in the study variables. For each test session, the exercise bout was divided into three equivalent 5‐min periods during which subjects were requested to use different pedal rates (spontaneous cadence, 70 and 90 rev min^?1). Pedal rate and kinematics data (instantaneous pedal velocity and angle of the ankle) were collected. The results show a higher spontaneous pedal rate in the late afternoon than in the early morning (p < 0.001). For a given pedal rate condition, there was a less variation in pedal velocity during a crank cycle in the morning than in the late afternoon. Moreover, diurnal variations were observed in ankle mobility across the crank cycle, the mean plantar flexion observed throughout the crank cycle being greater in the 18:00 h test session (p < 0.001). These results suggest that muscular activation patterns during a cyclical movement could be under the influence of circadian fluctuations.     

外源水杨酸对盐胁迫下大黄种子萌发及幼苗生长的影响

该研究以掌叶大黄、唐古特大黄和药用大黄种子为材料,采用双层滤纸培养法,设置系列浓度NaCl (0、100、150、200、250 mmol/L) 胁迫试验,以及系列浓度水杨酸(SA)溶液(0、50、100、150、200、250 mg/L)拌种和浸种后盐胁迫实验,测定3种大黄种子萌发及幼苗生长指标,揭示外源水杨酸对盐胁迫下大黄种子萌发及幼苗生长的影响。结果显示：(1)随NaCl浓度增大3种大黄种子的发芽率均呈直线下降趋势,且子叶、胚轴、根和苗等生长均受到强烈抑制。(2)在拌种条件下, 200 mmol/L NaCl胁迫下掌叶大黄苗长在200 mg/L SA处理下受到显著促进; 200 mmol/L NaCl浓度盐胁迫下唐古特大黄种子发芽率在250 mg/L SA处理下受到显著抑制;100 mmol/L NaCl胁迫下药用大黄种子发芽势在200 mg/L SA处理下受到显著抑制,其发芽率在150 mg/L SA处理下得到显著抑制,其苗长在250 mg/L SA处理下受到显著抑制。(3)在浸种条件下, 200 mmol/L NaCl胁迫下掌叶大黄种子发芽率在50 mg/L SA处理下显著提高,其幼苗根长和苗长的生长在250 mg/L SA处理受到显著促进;200 mmol/L NaCl胁迫下唐古特大黄种子的发芽势在200 mg/L SA处理下得到显著促进,其幼苗根和苗的生长在50 mg/L SA处理下得到显著促进;100 mmol/L NaCl 胁迫下药用大黄根和苗的生长在100 mg/L SA处理下均得到显著促进。研究表明,3种大黄种子和幼苗对盐胁迫的响应趋势一致,但对不同浓度SA拌种和浸种的响应有较大差异。     

The importance of seed reserves for seedling performance: an integrated approach using morphological,physiological, and stable isotope techniques

To investigate how seed reserves affect early seedling performance, we conducted a factorial greenhouse experiment using Lithocarpus densiflora (Tanoak). Seedlings were grown from large (5.8±0.7 g) and small (3.2±0.4 g) seeds and, following shoot emergence, seeds were either removed or left attached. Seedlings were harvested for quantification of biomass and ¹³C at seven time periods following seed removal (2, 4, 8, 16, 32, 64, 128 days) and seedling photosynthesis was measured three separate time periods (2–4, 49–82, 95–128 days after seed removal). Biomass increased for all seedlings, but the increase was significantly larger for seedlings with attached seeds than with removed seeds. Seed removal just after shoot emergence significantly decreased seedling biomass, but seed removal 64 days after shoot emergence had no effect on seedling biomass. Seedling photosynthesis per unit leaf area varied by time and seed presence, but not by seed size. At the first period, seedlings with attached seeds had significantly higher photosynthetic rates than seedlings with removed seeds, at the second period there was no effect of seed removal, and at the third time period seedlings with attached seeds had significantly lower photosynthetic rates than seedlings with removed seeds. Despite temporal variation in photosynthesis per unit leaf area, seedlings with attached seeds always had significantly greater leaf area than seedlings with removed seeds, resulting in significantly higher total plant photosynthesis at all three time periods. The ¹³C values of both the leaves and roots were more similar to that of the seed for seedlings with attached seeds than for seedlings with removed seeds, however, seed removal and seed size strongly affected root ¹³C. This study demonstrates that seed reserves have important effects on the early growth, physiology, and ¹³C of L. densiflora seedlings.     

A Temporal Dimension to the Influence of Pollen Rewards on Bee Behaviour and Fecundity in Aloe tenuior

The net effect of pollen production on fecundity in plants can range from negative – when self-pollen interferes with fecundity due to incompatibility mechanisms, to positive – when pollen availability is associated with increased pollinator visitation and fecundity due to its utilization as a reward. We investigated the responses of bees to pollen and nectar rewards, and the effects of these rewards on pollen deposition and fecundity in the hermaphroditic succulent shrub Aloe tenuior. Self-pollinated plants failed to set fruit, but their ovules were regularly penetrated by self-pollen tubes, which uniformly failed to develop into seeds as expected from ovarian self-incompatibility (or strong early inbreeding depression). Bees consistently foraged for pollen during the morning and early afternoon, but switched to nectar in the late afternoon. As a consequence of this differential foraging, we were able to test the relative contribution to fecundity of pollen- versus nectar-collecting flower visitors. We exposed emasculated and intact flowers in either the morning or late afternoon to foraging bees and showed that emasculation reduced pollen deposition by insects in the morning, but had little effect in the afternoon. Despite the potential for self-pollination to result in ovule discounting due to late-acting self-sterility, fecundity was severely reduced in artificially emasculated plants. Although there were temporal fluctuations in reward preference, most bee visits were for pollen rewards. Therefore the benefit of providing pollen that is accessible to bee foragers outweighs any potential costs to fitness in terms of gender interference in this species.     

Age-related differences in daily attention patterns in preschool, kindergarten, first-grade, and fifth-grade pupils

The purpose of this study was to examine age-related differences in the daily attention patterns of preschool, kindergarten, first-grade, and fifth-grade pupils by means of a cross-sectional sample of 4-11-year-old French students. The importance of this study comes from the need to understand attention and apply the information it provides in educational settings. The first study conducted in a school setting with three age groups (4-5-, 6-7-, and 10-11-year-olds) demonstrated a rapid rhythmicity (60 minute period) for preschoolers (4-5 years old), with higher performance at the beginning of a teaching session. This pattern evolved until the fifth grade (10-11-year-olds), after which the temporal variation in attention was comparable to that of working adults, with fluctuations occurring on a half-day basis. The children's scores on crossing-out tests rose during the morning, declined in the early afternoon, and then rose again later during the afternoon. The second study enhanced our understanding of the change of the rhythm in attention of 4-7-year-old pupils. The rapid daily rhythmicity, linked to a session effect, seems to gradually disappear as children move from preschool 2 to kindergarten (4-5- to 5-6-year-olds) and then on to first grade (6-7-year-olds), where the daily attention patterns are closer to the standard pattern found by chronopsychology studies. The evolving patterns obtained from group means were confirmed by analysis of individual patterns. Exploratory statistical analysis of the data provided greater detail on the observed interindividual patterns, indicating that within each school grade, the attention patterns of some children are similar to the standard pattern while the attention patterns of others are more atypical. Deviations were mainly found in the 5-6-year-old age range (kindergarteners). The greatest 'mixture' of patterns was observed in the kindergartners (5-6-year-olds). Age plays a role not only in modifying daily changes but also in the distribution of interindividual differences in daily fluctuations, which occur most when children are of kindergarten age (5-6 years of age).     

Diurnal Variation in Glucose Tolerance: Associated Changes in Plasma Insulin,Growth Hormone,and Non-esterified

Oral glucose tolerance tests were performed in the morning and afternoon of separate days on 31 people derived from a normal population sample. Blood sugar levels were higher in the afternoon test from and including 60 minutes after the glucose load. The degree of diurnal variation was similar in men and women, but greater in the older half of the group. It was negatively correlated with the degree of obesity. The plasma insulin response was less at the 30 minute time point in the afternoon, but significantly exceeded the morning values at 120 and 150 minutes after the glucose load. Growth hormone levels were similar in morning and afternoon tests. Fasting non-esterified fatty acid levels were significantly higher before the afternoon test.The relatively impaired glucose tolerance in the afternoon is associated with a delayed insulin response to the glucose load. This seems unlikely to be the sole explanation, however, and increased non-esterified fatty acid metabolism with a consequent decrease in glucose disposal may also contribute.     

Diurnal Variation in Oral Glucose Tolerance: Blood Sugar and Plasma Insulin Levels Morning,Afternoon, and Evening

Twenty-four subjects received three oral glucose tolerance tests, in the morning, afternoon, and evening of separate days. The mean blood sugar levels in the afternoon and evening tests were similar, and they were both significantly higher than those in the morning test. Plasma immunoreactive insulin levels, however, were highest in the morning test. The pattern of insulin levels during the afternoon and evening tests resembled that described as typical of maturity-onset diabetes.     

Age‐Related Differences in Daily Attention Patterns in Preschool,Kindergarten, First‐Grade,and Fifth‐Grade Pupils

The purpose of this study was to examine age‐related differences in the daily attention patterns of preschool, kindergarten, first‐grade, and fifth‐grade pupils by means of a cross‐sectional sample of 4–11‐year‐old French students. The importance of this study comes from the need to understand attention and apply the information it provides in educational settings. The first study conducted in a school setting with three age groups (4–5‐, 6–7‐, and 10–11‐year‐olds) demonstrated a rapid rhythmicity (60 minute period) for preschoolers (4–5 years old), with higher performance at the beginning of a teaching session. This pattern evolved until the fifth grade (10–11‐year‐olds), after which the temporal variation in attention was comparable to that of working adults, with fluctuations occurring on a half‐day basis. The children's scores on crossing‐out tests rose during the morning, declined in the early afternoon, and then rose again later during the afternoon. The second study enhanced our understanding of the change of the rhythm in attention of 4–7‐year‐old pupils. The rapid daily rhythmicity, linked to a session effect, seems to gradually disappear as children move from preschool 2 to kindergarten (4–5‐ to 5–6‐year‐olds) and then on to first grade (6–7‐year‐olds), where the daily attention patterns are closer to the standard pattern found by chronopsychology studies. The evolving patterns obtained from group means were confirmed by analysis of individual patterns. Exploratory statistical analysis of the data provided greater detail on the observed interindividual patterns, indicating that within each school grade, the attention patterns of some children are similar to the standard pattern while the attention patterns of others are more atypical. Deviations were mainly found in the 5–6‐year‐old age range (kindergarteners). The greatest ‘mixture’ of patterns was observed in the kindergartners (5–6‐year‐olds). Age plays a role not only in modifying daily changes but also in the distribution of interindividual differences in daily fluctuations, which occur most when children are of kindergarten age (5–6 years of age).     

Diurnal variation of salivary cortisol in captive African elephants (Loxodonta africana) under routine management conditions and in relation to a translocation event

The present study assessed the diurnal variation in salivary cortisol in captive African elephants during routine management (baseline) and in relation to a potential stressor (translocation) to evaluate to what extent acute stress may affect diurnal cortisol patterns. Under baseline conditions, we collected morning and afternoon saliva samples of 10 animals (three zoos) on different days in two study periods (n = 3–10 per animal, daytime and period). Under stress conditions, we sampled the transported cow (newcomer) and the two cows of the destination zoo before and after the transport in the morning and afternoon (n = 3–9 per animal, daytime and transport phase), as well as after the first introduction of the newcomer to the bull (n = 1 per animal). Cortisol was measured in unextracted samples by enzyme immunoassay. Under baseline conditions, we observed the expected diurnal variation with higher cortisol levels in the morning than in the afternoon. Under stress conditions, neither a significant difference between pre- and posttransport, nor between morning and afternoon levels was found. The percentage difference between morning and afternoon cortisol after the transport, however, was remarkably lower than before the transport in the newcomer potentially indicating a stress response to familiarization. Saliva samples taken immediately after the introduction of the newcomer to the bull revealed a marked cortisol increase. Our findings indicate that stressors may disturb the diurnal cortisol rhythm. Furthermore, provided that samples can be collected promptly, salivary cortisol is a useful minimally invasive measure of physiological stress in the African elephant.     

Respiratory metabolism in mangrove seedlings

The respiratory gaseous exchanges of detached whole mangrove seedlings (Avicennia, Bruguiera, Rhizophora) in a range of O₂ concentrations from 0 to 21% (air) were markedly reduced by the presence of external CO₂. Aerobic respiration decreased steadily for 16 days but the RQ remained at unity.     

Episodic corticosterone secretion in the female rat

Studies conducted in several laboratories have shown primate glucocorticoid secretion to occur episodically. In light of the methodological, as well as physiological importance of this finding, the present study was undertaken to determine whether the rat corticosteroid secretion also occurs episodically. Female rats were outfitted with chronic intravenous cannulas, and 1 week later 200 units of heparin were injected through the implanted cannula and blood samples (0.3-0.4 ml) were collected from each rat every 10 min for 3 h during the morning (06.00-10.00 h) or during the afternoon (16.00-19.00 h) (lights on from 05.00 to 19.00 h). Plasma corticosterone levels in cannulated rats showed fluctuations indicative of episodic secretion. The pattern of plasma corticosterone levels was characterized by periodic rapid increases in hormone concentration during both the morning and afternoon sampling periods; the occurrence of these hormonal fluctuations did not have a characteristic frequency. When the data were grouped to obtain single morning and afternoon values, the AM-PM difference was significant (p < 0.005). Collectively, these data suggest that in the rat, adrenal corticosteroids are secreted episodically.     

Diurnal Variation in Oral Temperature,Sleepiness, and Performance of High School Girls

Evaluation of rhythmic fluctuations of physical and mental variables should be of special significance for the understanding of students' performance and setting the schedules of school activities. The present study investigated the pattern of diurnal variation in oral temperature, sleepiness and performance of a group of adolescents undergoing a daytime school schedule. Eighteen girls (mean age 16 years-old), who attended the same class from 0715h to 1645h, were tested on seven days. They measured their oral temperature, quantified their sleepiness level by means of a visual analogue scale, and completed the following tests: letter cancellation test, addition test, and a simple motor task. One-way ANOVA statistics for repeated measures was used in order to verify the effect of test time on oral temperature, sleepiness and performance. Possible correlations between the level of sleepiness and performance were investigated by means of Spearman rank correlation. The results revealed significant time of day effect on all variables, except for the number of addition errors. Oral temperature values showed an increase from morning to afternoon. Letter cancellation, motor task and addition scores increased from early morning to late afternoon, showing rapid fluctuations throughout the day. Sleepiness level was negatively correlated with letter cancellation scores during the first three tests of the day. In agreement with other work, the diurnal variation of oral temperature, letter cancellation and addition test showed an improvement as the day progressed. Sleepiness, on the other hand, decreased throughout the day, with the highest level associated with the first test of the day, suggesting a circadian pattern of variation rather than a cumulative effect due to school activities.     

A field test of food information transfer in communally roosting greenfinches Carduelis chloris

We tested whether communally roosting greenfinches Carduelis chloris obtained information from conspecifics on the distribution of unpredictable food sources (sunflower seeds, Helianthus sp.) during a severe winter. Seeds were provided at randomly chosen sites in the afternoon and the numbers of greenfinches at these bait sites in the afternoon and the following morning were compared. Numbers did not increase from the afternoon to the morning in eight out of nine trials where greenfinches turned up at the bait sites. Attraction to the bait decreased with increasing ambient temperatures, more birds turning up during severe frost. Subordinate females were attracted to the bait more frequently than dominant male greenfinches.     

The diurnal course of plant water potential,stomatal conductance and transpiration in a papyrus (Cyperus papyrus L.) canopy

Summary The diurnal course of water potential, stomatal conductance and transpiration was measured on mature umbels (the major evaporating surface) of papyrus (Cyperus papyrus L.) growing in a fringing swamp on Lake Naivasha, Kenya.Umbel water potential declined only slightly during the morning but fell rapidly after midday to a minimum value of-1.5 M Pa in early afternoon. The two main structures forming the umbels, the bracteoles and rays, showed similar patterns of change of stomatal conductance throughout the day. The values of conductance indicate major stomatal opening during the morning, partial midday closure and some recovery of opening during the afternoon.It appears that the increase in water vapour pressure deficit of the air is the major cause of the midday closure of the stomata and that plant water potential has little effect. The reason why transpiration is reduced at high vapour pressure deficits when water is freely available to the roots is not clear. However, it is speculated that the restricted water movement into the plant from the anaerobic root environment has the effect of reducing the uptake of toxic ferrous iron.The daily total of canopy transpiration is estimated to be 12.5 mm, twice the value previously reported for papyrus but similar to daily valus determined for other wetland communities.     

Studies on the behaviour and substratum preference in juveniles of the marine prawn,Metapenaeus monoceros (Fabricius)

Circadian rhythmicity in the behaviour of the marine prawn, Metapenaeus monoceros (Fab) and its substratum preference has been observed under laboratory conditions. In the morning at 9. a.m. 80% prawns remain buried and in the afternoon at 3 p.m. 60% burrowing was observed. A contrasting situation was observed in the night i.e. 17% burrowing at 9 p.m. and 30% burrowing at 3 a.m. was registered. In the second set of experiments juveniles were subjected to four types of substrata viz. mud, black fine sand, white coarse sand and stones. It was noted that M. monoceros showed more affinity towards the mud and less preference to other substrata. The obtained results are discussed to provide clues for prawn fishing.This work was supported by I.C.A.R., New Delhi through a project on Reprod. Endocr. Edible prawns.     

Diurnal Variation in Oral Temperature, Sleepiness, and Performance of High School Girls

Evaluation of rhythmic fluctuations of physical and mental variables should be of special significance for the understanding of students' performance and setting the schedules of school activities. The present study investigated the pattern of diurnal variation in oral temperature, sleepiness and performance of a group of adolescents undergoing a daytime school schedule. Eighteen girls (mean age 16 years-old), who attended the same class from 0715h to 1645h, were tested on seven days. They measured their oral temperature, quantified their sleepiness level by means of a visual analogue scale, and completed the following tests: letter cancellation test, addition test, and a simple motor task. One-way ANOVA statistics for repeated measures was used in order to verify the effect of test time on oral temperature, sleepiness and performance. Possible correlations between the level of sleepiness and performance were investigated by means of Spearman rank correlation. The results revealed significant time of day effect on all variables, except for the number of addition errors. Oral temperature values showed an increase from morning to afternoon. Letter cancellation, motor task and addition scores increased from early morning to late afternoon, showing rapid fluctuations throughout the day. Sleepiness level was negatively correlated with letter cancellation scores during the first three tests of the day. In agreement with other work, the diurnal variation of oral temperature, letter cancellation and addition test showed an improvement as the day progressed. Sleepiness, on the other hand, decreased throughout the day, with the highest level associated with the first test of the day, suggesting a circadian pattern of variation rather than a cumulative effect due to school activities.