The Influence of Exogenous Nutrients on the Abundance of Yeasts on the Phylloplane of Turfgrass

Four experiments were conducted to assess the effect of foliar applications of various nutrient solutions on the phylloplane yeast community of tall fescue (Festuca arundinacea Schreb.). In the first three experiments, increasing concentrations of sucrose (2–16%), yeast extract (0.5–2.5%), and sucrose plus yeast extract (2.5–18.5% total) were applied and the yeast colony forming units (cfu) enumerated 14 h later by dilution plating. Significant positive linear relationships were observed between the number of yeast cfu and applications of both yeast extract and sucrose plus yeast extract. Foliar applications of sucrose alone had no significant effect on yeast community abundance, indicating that phylloplane yeasts of turfgrass are not limited by the amount or availability of carbohydrates. In the fourth experiment, five different solutions were applied to tall fescue to investigate the response of the yeast community to organic and inorganic nitrogen sources. Tryptone or yeast extract, both with considerable amino acid composition, significantly increased the yeast population, while yeast nitrogen base (with or without amino acids) and ammonium sulfate had no affect on yeast abundance. These results suggest that organic nitrogen stimulate yeast community growth and development on the phylloplane of tall fescue, while carbohydrates, inorganic nitrogen, and non-nitrogenous nutrients have little positive effect.     

Variable adhesion and diurnal population patterns of epiphytic yeasts on creeping bentgrass

Irrigation and an in vitro agitation assay were used to determine the percentage of the epiphytic yeast community (Cryptococcus, Pseudozyma, Rhodotorula, and Sporobolomyces) adhering to the phylloplane of creeping bentgrass (Agrostis palustris (Huds.) Pers.). Colony-forming units (cfu) of total epiphytic yeast populations (adherent and nonadherent cells) and of adherent populations (cells not removed by agitation) were determined by leaf washing and dilution plating. In an in vitro assay, 40.0% and 57.1% of the yeast adhered to the leaves, whereas, in initial field trials the percentage of adherent yeasts ranged from 40.0% to 71.9% of the total population. Adherent yeast cfu on leaves in the morning were significantly lower on bentgrass (8.0 x 103 to 3.1 x 104 cfu.cm(-2)) compared with total yeast cfu (1.4 x 104 to 4.7 x 104 cfu.cm(-2)) on the nonirrigated control. No differences in yeast populations were observed between irrigated and nonirrigated plots 2 h after the 0900 treatments. Yeast populations followed a diurnal pattern, with larger cfu recovered from bentgrass leaves in the morning and significantly lower populations recovered in the afternoon. At 1400 the adherent yeast were 83.1%-100% of the total yeast population recovered from the leaves. The relative adhesiveness of the epiphytic yeast community on bentgrass leaves is dynamic with nonadherent cells making up a larger percentage of the population in the mornings than the afternoons.     

Collegiate rowing crew performance varies by morningness-eveningness

During adolescence and early adulthood, most humans are predisposed developmentally, both biologically and socially, toward evening/night activity. The morningness-eveningness (M-E) tendency to be an evening-preferring (E-type) rather than a morning-preferring (M-type) or intermediate/neither (N-type) "chronotype" may affect athletic performance at various times of day. This study evaluated M-E effects on rowing performance of an intact, experienced, university club crew with near-daily early morning (0500-0700 hours) and late afternoon (1630-1800 hours) training schedules. The hypothesis tested was that chronotype would modify circadian effects during morning and afternoon performances. Eight men and eight women (mean age 19.6 +/- 1.5 years) were tested in a randomized, counterbalanced design. A standard qualifying 2000-m ergometer rowing sprint and a nonroutine standing broad jump task were measured during early morning and late afternoon, separated by 3 days of rest. Each subject's chronotype was determined using two standard self-rating M-E scales, resulting in eight E-type (three women/five men), four M-type (two women/two men), and four N-type (three women/one man) subjects. The rowing results show that E-type and N-type subjects did not differ between morning and afternoon rowing performances, whereas M-type subjects rowed significantly faster in the morning. In contrast, the standing broad jump showed no consistent time-of-day or chronotype effect. These findings suggest that basic performance timing in young athletes is determined to some extent by naturally occurring M-E predispositions. Further, modification of time-of-day influences may be possible by routine practice at the same time each day, as was suggested here by the absence of evening superiority in performances. Understanding their personal M-E tendencies could allow young athletes to arrange training schedules at specific times of day to help counteract any natural circadian influences that might work against their performance.     

Effect of foliar disease on the epiphytic yeast communities of creeping bentgrass and tall fescue

The effect of mechanical wounding or foliar diseases caused by Sclerotinia homoeocarpa or Rhizoctonia solani on the epiphytic yeast communities on creeping bentgrass and tall fescue were determined by leaf washing and dilution plating. Total yeast communities on healthy bentgrass and tall fescue leaves ranged from 7.9 x 103 to 1.4 x 105 CFU.cm-2 and from 2.4 x 103 to 1.6 x 104 CFU.cm-2, respectively. Mechanically wounded leaves (1 of 2 trials) and leaves with disease lesions (11 of 12 trials) supported significantly larger communities of phylloplane yeasts. Total yeast communities on S. homoeocarpa infected or R. solani infected bentgrass leaves were 3.6-10.2 times and 6.2-6.4 times larger, respectively, than the communities on healthy leaves. In general, healthy and diseased bentgrass leaves supported larger yeast communities than healthy or diseased tall fescue leaves. We categorized the majority of yeasts as white-pigmented species, including Cryptococcus laurentii, Cryptococcus flavus, Pseudozyma antarctica, Pseudozyma aphidis, and Pseudozyma parantarctica. The percentage of pink yeasts in the total yeast community ranged from 2.6% to 9.9% on healthy leaves and increased to 32.0%-44.7% on S. homoeocarpa infected leaves. Pink-pigmented yeasts included Rhodotorula glutinis, Rhodotorula mucilaginosa, Sakaguchia dacryoidea, and Sporidiobolus pararoseus. Foliar disease significantly affected community size and composition of epiphytic yeasts on bentgrass and tall fescue.     

The effect of training at a specific time of day: a review

This article focuses on physical performances after training at a specific time of day. To date, although the effect of time of day on aerobic performances appears to be equivocal, during anaerobic exercises, the effect of time of day has been well established with early morning nadirs and peak performances in the late afternoon. These diurnal rhythms can be influenced by several factors such as the regular training at a specific time of day. Indeed, regular training in the morning hours may increase the lower morning performances to the same or even higher level as their normal diurnal peak typically observed in the late afternoon by a greater increase of performance in the evening. However, regular training in the evening hours may increase the morning-evening (i.e., amplitude of the rhythm) difference by a greater increase of performance in the late afternoon. Therefore, adaptations to training are greater at the time of day at which training is regularly performed than at other times. Nevertheless, although modifications in resting hormones concentrations could explain this time-of-day specific adaptations, precise information on the underlying mechanisms is lacking.     

Evidence of daily spawning in natural populations of the New Zealand snapper Pagrus auratus (Sparidae)

Synopsis New Zealand snapper, Pagrus auratus, were captured by trawling from NE New Zealand over two successive spawning seasons, and examined for acute temporal changes in gonad condition. Fish with oocytes completing final oocyte maturation predominated during the morning, with a peak in ovulated fish occurring just after midday. Afternoon catches were dominated by fish in which the most advanced oocytes had yet to begin final maturation. This suggests that ovulation is synchronised to occur soon after midday, and the high proportion (up to 100% of the catch) of fish with particular gonad stages captured at any one time indicates that daily spawning involves most of the population. Diurnal changes in oocyte diameter support a daily spawning rhythm, with numbers of large hydrated oocytes peaking in the late morning, followed by the disappearance of these oocyte stages in the afternoon. Snapper captured alive by longlining were returned to the laboratory to examine the relationship between ovulation and probable time of spawning. Unovulated fish generally ovulated close to midday on the day of capture (morning captures), or the following day (afternoon captures). The viability of ovulated eggs (proportion undergoing division after fertilization) decreased markedly after oviduct residence times of over 8 hours. This suggests that natural spawning occurs before the late evening. The results of this study are consistent with anecdotal evidence suggesting that spawning occurs every day during the late afternoon or early evening, and is similar to the reproductive patterns displayed by a number of closely related sparids. Department of Zoology, University of Otago, PO Box 56, Dunedin, New Zealand     

Circadian variations in psychophysiological responses to heat exposure and exercise

Ten healthy men were tested at 0600, 1200, 1800 and 2400 hours on different days at rest in a laboratory at room temperature followed by 1 h of heat exposure in a climatic chamber at 42 degrees C, 60% rh (50 min rest and 10 min exercise on a cycle ergometer at 50% VO2max). Heart rate, blood pressure, rectal temperature Tre, metabolic rate, number connection test, visual and auditory reaction time, flicker test and catecholamine excretion were measured. Heat exposure and exercise caused lower heart rate acceleration at 2400 hours than at 0600 and 1200 hours, the smallest increase of Tre at 1800 hours, and an increase in metabolic rate greater at 1200 than at 1800 hours. In the afternoon, when, according to the circadian rhythm, the body temperature is highest, the additional heat load produced the smallest physiological effects. Performance efficiency, after heat exposure combined with physical exercise, improved slightly, but diurnal variations did not show significant circadian rhythm.     

Phase Typing of Patients with Seasonal Affective Disorder: A Test for the Phase Shift Hypothesis

The study evaluates the phase-shift hypothesis for seasonal affective disorder (Lewy et al., 1987, 1988) in parallel-design comparison of effects of morning (800-1000) or afternoon (1600-1800) light treatment on mood and circadian phase. Subjective arousal, body temperature, melatonin and cortisol were measured at 800, 1200, 1600, 2000 and 2400 in 23 women with seasonal depression and 20 controls before and after a week of bright light (2 hours per day). The rates of clinical response to both treatments were similar. Comparison of circadian variations did not provide evidence for significant phase-delay in patients compared to controls. However, morning light produced significant phase advance in patients, but not in controls. Also we found that advance phase shifts in well-responded patients were more often than in patients with worse response and controls. Before light treatment phase concordance between different variables in patients was lower compared to either themselves after light treatment or controls before and after light treatment. Dependence of antidepressant response to light from pretreatment circadian phases was also observed. Those patients who responded worse to morning light tended to have advance circadian phases, while those who responded worse to afternoon light tended to have delay phases. Although some results are lending support for the phase-shift hypothesis, other explanations for mechanisms by which biological rhythms are implicated in winter depression and light treatment might be suggested.     

Circadian Rhythm in Serum Iron Levels

This study was aimed at assessing the circadian rhythm of serum iron levels in Chinese healthy subjects. The project was conducted in 19 healthy, Chinese male subjects following a 4-day diet equilibration. Blood samples were collected on day 5 at 0800, 1000, 1200, 1400, 1600, 1800, 2000, and 2400 hours to determine endogenous serum iron concentrations. Iron concentrations were determined using an inductively coupled plasma mass spectrometry. Iron concentration was decreased from morning to afternoon. The minimum value of iron level was 1,987 μg/L at 2000 hours while the maximum was 2,229 μg/L at 1000 hours, and 2,278 μg/L at 1400 hours, respectively, the amplitude was 291 μg/L. This study indicates that when assessing the bioequivalence of iron formulations, baseline levels of iron (obtained before dosing) should not be subtracted simply from the amount obtained on the drug dosing day to yield the net effect of iron formulation administration. More valid methods to optimize the design of such bioequivalence studies should be taken into consideration.     

Phase Typing of Patients with Seasonal Affective Disorder: A Test for the Phase Shift Hypothesis

The study evaluates the phase-shift hypothesis for seasonal affective disorder (Lewy et al., 1987, 1988) in parallel-design comparison of effects of morning (800-1000) or afternoon (1600-1800) light treatment on mood and circadian phase. Subjective arousal, body temperature, melatonin and cortisol were measured at 800, 1200, 1600, 2000 and 2400 in 23 women with seasonal depression and 20 controls before and after a week of bright light (2 hours per day). The rates of clinical response to both treatments were similar. Comparison of circadian variations did not provide evidence for significant phase-delay in patients compared to controls. However, morning light produced significant phase advance in patients, but not in controls. Also we found that advance phase shifts in well-responded patients were more often than in patients with worse response and controls. Before light treatment phase concordance between different variables in patients was lower compared to either themselves after light treatment or controls before and after light treatment. Dependence of antidepressant response to light from pretreatment circadian phases was also observed. Those patients who responded worse to morning light tended to have advance circadian phases, while those who responded worse to afternoon light tended to have delay phases. Although some results are lending support for the phase-shift hypothesis, other explanations for mechanisms by which biological rhythms are implicated in winter depression and light treatment might be suggested.     

The effect of training at the same time of day and tapering period on the diurnal variation of short exercise performances

The purpose of this investigation was to assess the effects of training and tapering at the same time of the day on the diurnal variations of short exercise performances. Thirty-one physically active men underwent 12 weeks of lower-extremity resistance training and 2 weeks of tapering. These subjects were matched and randomly assigned to a morning training group (MTG, training times 0700-0800 hours, n = 10), an evening training group (ETG, training times 1700-1800 hours, n = 11), and a control group (CG, completed all tests but did not train, n = 10). Muscular strength and power testing was conducted before (T0) and after 12 weeks of training (T1) and after 2 weeks of tapering (T2) in the morning (0700-0800 hours) and in the evening (1700-1800 hours). All morning and evening tests were performed in separate sessions (minimum interval = 36 hours) in a randomized design. In T0, the oral temperature and performances during the Wingate, vertical jump (squat jump and countermovement jump), and maximal voluntary contraction tests were higher in the evening than in the morning for all the groups. In T1, these diurnal variations were blunted in the MTG and persisted in the ETG and CG. In T2, the 2 weeks of tapering resulted in further time of day-specific adaptations and increases in short-term maximal performances. However, there was no significant difference in the relative increase between the MTG and the ETG after both training and tapering. From a practical point of view, if the time of competition is known, training and tapering sessions before a major competition must be conducted at the same time of the day at which one's critical performance is programmed. Moreover, if the time of the competition is not known, a tapering phase after resistance training program could be performed at any time of the day with the same benefit.     

Daily Changes in the Competence for Photo- and Gravitropic Response by Potato Plantlets

Competence for phototropic (PT) and gravitropic (GT) bending by potato plantlets grown in vitro manifests regular daily changes indicating possible involvement of circadian regulation. Unilateral stimulation of plantlets with blue light at dawn resulted in moderate PT response regarding both attained curvature and long lag phase. The PT response was the strongest between 8:00 and 12:00 h. Throughout the afternoon and in the evening, bending rate and maximal PT curvature declined significantly until 23:00 h. The GT response was fastest and strongest for plantlets stimulated early in the morning and late in the evening. During the rest of the day, GT competence did not change much apart from a minimum at 15:00. In conditions comprising either prolonged day or prolonged night, plantlets appeared to maintain rhythmicity of competence for PT and GT at least in the short-term. Introduction of a dark period prior to the tropic stimulation at 11:00 h when both PT and GT responses were strong resulted in the opposite effect: PT was depressed, and GT was enhanced. There was a time threshold of 60 min for the duration of the dark period so the plants can sense interruption in the daylight. Levels of relative expression of a PHOT2 gene indicate rhythmic daily changes. The PHOT2 gene was present at high levels during morning hours and late in the evening. As the mid-day and the afternoon hours approached, PHOT2 expression decreased and reached a daily minimum at 17:00 h. We believe that our data offer strong support for the conclusion that there is an involvement of circadian rhythms in control of both PT and GT.     

Grazing and an invasive grass confound spatial pattern of exotic and native grassland plant species richness

Previous work has shown exotic and native plant species richness are negatively correlated at fine spatial scales and positively correlated at broad spatial scales. Grazing and invasive plant species can influence plant species richness, but the effects of these disturbances across spatial scales remain untested. We collected species richness data for both native and exotic plants from five spatial scales (0.5–3000 m²) in a nested, modified Whittaker plot design from severely grazed and ungrazed North American tallgrass prairie. We also recorded the abundance of an abundant invasive grass, tall fescue (Schedonorus phoenix (Scop.) Holub), at the 0.5-m² scale. We used linear mixed-effect regression to test relationships between plant species richness, tall fescue abundance, and grazing history at five spatial scales. At no scale was exotic and native species richness linearly related, but exotic species richness at all scales was greater in grazed tracts than ungrazed tracts. Native species richness declined with increasing tall fescue abundance at all five spatial scales, but exotic species richness increased with tall fescue abundance at all but the broadest spatial scales. Severe grazing did not reduce native species richness at any spatial scale. We posit that invasion of tall fescue in this working landscape of originally native grassland plants modifies species richness-spatial scale relationships observed in less disturbed systems. Tall fescue invasion constitutes a unique biotic effect on plant species richness at broad spatial scales.     

Spot determinations of urinary cortisol for the screening of Cushing's syndrome.

The usefulness of spot determination of urinary cortisol in the screening of Cushing's syndrome was evaluated by measuring the cortisol concentration in randomly sampled urine in 68 normal subjects and in 9 patients with Cushing's syndrome. The urinary cortisol concentration in the morning was significantly higher in patients with Cushing's syndrome but some overlap existed between normal subjects and patients with Cushing's syndrome. In contrast, there was a clear discrimination between two groups when urinary cortisol was measured in the late evening: urinary cortisol was lower than 75 micrograms per gram creatinine (microgram/gCr) in normal subjects but higher than 150 micrograms/gCr in patients with Cushing's syndrome. When 1 mg dexamethasone was administered at 2300 h in the evening, spot urinary cortisol the next morning was less than 80 micrograms/gCr in normal subjects while it was above 100 micrograms/gCr in patients with Cushing's syndrome. Dexamethasone-induced suppression of urinary cortisol in normal subjects lasted until late in the afternoon, which allows sampling of urine at any time in the morning and possibly in the afternoon. These results suggest the usefulness of spot determination of urinary cortisol in the screening of Cushings' syndrome.     

Inhibin secretion during the rat estrous cycle: relationships to FSH secretion and FSH beta subunit mRNA concentrations

Serum inhibin and FSH and FSH beta subunit mRNA levels were measured at 3h intervals throughout the 4 day estrous cycle in female rats and hourly between 1000 and 2400 h of proestrus. On proestrus, serum inhibin concentrations fell during the late morning-early afternoon, then increased transiently during the late afternoon gonadotropin surges. Inhibin levels decreased during the late evening of proestrus, coincident with the FSH surge-related rise in FSH beta mRNA levels. Serum inhibin remained relatively stable during estrus and early metestrus, but rose during the late evening of metestrus and remained elevated until early diestrus. FSH beta mRNA levels were elevated on late estrus and early metestrus and declined during the evening of metestrus as serum inhibin levels increased. These data show that concentrations of serum inhibin change during the estrous cycle and that a general inverse relationship exists between serum inhibin and FSH levels and FSH beta mRNA concentrations in the pituitary. This suggests that inhibin may inhibit FSH beta gene expression and FSH secretion during the 4 day cycle in female rats.     

The impact of time of day on the gait and balance control of Alzheimer’s patients

Alzheimer’s patients suffer from circadian dysregulation. The aim of this study was to examine the evolution of balance control and gait at different times of the day (11:00, 14:00, 18:00) in order to identify whether Alzheimer’s patients were more likely to fall at certain periods of the day. Spatio-temporal parameters of centre of foot pressure displacements were measured with a force platform and spatio-temporal parameters of walking were evaluated with a gait analysis device. The results highlighted that balance control was worse in the evening and the afternoon than in the morning. Furthermore, the walking speed was faster and support duration, swing duration and cycle duration were shorter in the evening than in the morning and afternoon. The combined analysis of balance control and gait parameters revealed that balance control and walking are concomitantly altered in the evening which increases the fall risk in the evening, in comparison with the morning, for Alzheimer’s patients.     

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.     

Effects of grazing endophyte-infected tall fescue on eCG and progestogen concentrations from gestation days 21 to 300 in the mare

The influence of grazing endophyte-infected tall fescue on endometrial cup formation and function, progestogen production, and embryonic and fetal development were examined in pregnant mares between Day 21 and Day 300 of gestation. Total immunoreactive progestogens and equine chorionic gonadotropin (eCG) concentrations were compared between untreated controls (endophyte-free, n = 12) and treated mares (endophyte-infected, n = 12). There were no differences in endometrial cup formation or function, as determined by eCG concentrations at Days 45, 60, 75, 90 and 120 (P > 0.05) between mares grazing endophyte-infected and endophyte-free tall fescue. Mares grazing the endophyte-infected tall fescue had lower total progestogen concentrations (P < 0.01) from Days 90 to 120 than the mares grazing endophyte-free tall fescue. Embryonic development based on mean vesicle height was not affected by endophyte exposure. No pregnancies were lost by mares in either treatment group during the trial period. The results of this study indicate that grazing endophyte-infected tall fescue between Day 21 and Day 300 does not alter endometrial cup formation and function, or result in increased pregnancy losses during this period. Lower progestogen concentrations between Days 90 and 120 with exposure to endophyte-infected tall fescue could reflect decreased luteal progesterone production.     

Diel variations in carbonate incorporation into otoliths in goldfish

When D-[¹⁴C-U]-glucose was administered intraperitoneally into goldfish Carassius amatus at 20° C and 12L: 12D (dark period 1800–0600 hours) at 0600, 1200, 1800, 2400 and 0600 hours on the following day, glucose was metabolized to release ¹⁴CO₂ and then it was incorporated into otoliths as carbonate. The rate of metabolic activity, judging from the ratio of inorganic to organic radiocarbon in plasma, was low during the dark period. Carbon incorporation into otoliths was also minimized during 1800–2400 h. When fish were exposed to ambient water containing NaH¹⁴CO₃, plasma radioactivity was lowest during 1800–2400 hours, during which time carbon incorporation into otoliths was lowest. Plasma total CO₂ levels markedly increased during the dark period. These results clearly indicate that carbonate formation in otoliths has a diel variation with a nadir lasting 6 h from 1800 to 2400 hours under the photoperiod used.     

The effects of time of day-specific resistance training on adaptations in skeletal muscle hypertrophy and muscle strength: A systematic review and meta-analysis

The present paper endeavored to elucidate the topic on the effects of morning versus evening resistance training on muscle strength and hypertrophy by conducting a systematic review and a meta-analysis of studies that examined time of day-specific resistance training. This systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines with searches conducted through PubMed/MEDLINE, Scopus, and SPORTDiscus databases. The Downs and Black checklist was used for the assessment of the methodological quality of the included studies. Studies that examined the effects of time of day-specific resistance training (while equating all other training variables, such as training frequency and volume, between the groups) on muscle strength and/or muscle size were included in the present review. The random effects model was used for the meta-analysis. Meta-analyses explored (1) the differences in strength expression between morning and evening hours at baseline; (2) the differences in strength within the groups training in the morning and evening by using their post-intervention strength data from the morning and evening strength assessments; (3) the overall differences between the effects of morning and evening resistance training (with subgroup analyses conducted for studies that assessed strength in the morning hours and for the studies that assessed strength in the evening hours). Finally, a meta-analysis was also conducted for studies that assessed muscle hypertrophy. Eleven studies of moderate and good methodological quality were included in the present review. The primary findings of the review are as follows: (1) at baseline, a significant difference in strength between morning and evening is evident, with greater strength observed in the evening hours; (2) resistance training in the morning hours may increase strength assessed in the morning to similar levels as strength assessed in the evening; (3) training in the evening hours, however, maintains the general difference in strength across the day, with greater strength observed in the evening hours; (4) when comparing the effects between the groups training in the morning versus in the evening hours, increases in strength are similar in both groups, regardless of the time of day at which strength assessment is conducted; and (5) increases in muscle size are similar irrespective of the time of day at which the training is performed.