Daylight Period Research Articles

Assessment of cloudless-to-cloud transition zone from downwelling longwave irradiance measurements

The transition zone has been defined as corresponding to atmospheric conditions between cloud-free (albeit containing a suspension of dry particles, i.e. aerosol) and clouds (air containing a suspension of highly hydrated particles, i.e. droplets or ice crystals). Since clouds significantly affect the infrared radiation reaching the Earth's surface, broadband infrared measurements, which are usually performed with pyrgeometers, are implicated in some of the methods proposed for detecting clouds. The present work uses one of these methods to characterize the transition between cloud-free and cloudy conditions. Two years of downwelling longwave irradiance measured with a pyrgeometer located in Girona (in the northeast of the Iberian Peninsula) have been used to determine the values of a cloud detection index. The method must be previously tuned against a set of selected cloud-free cases to detect cloudiness to a certain confidence level. The effect of changing the detection confidence level was studied and used to derive the occurrence of transition conditions. The performance of the cloudiness detection method, with the support of observations by broadband shortwave instruments, ceilometer retrievals and images captured by hemispherical camera, was then analyzed for some short time periods. The duration of the transition periods is presented here, showing that 41% are very short (10 min, the temporal resolution of the detection method), that the median of the distribution is about 20 min, and that, although periods of more than one hour are observed, longer durations steadily decrease in frequency. It was found that 10–15% of the observations included may correspond to the transition zone, thus strengthening the estimations from other shortwave-based methods that are only suitable for daylight periods.

Comparison of Urban Heat Island Diurnal Cycles under Various Atmospheric Conditions Using WRF-UCM

The rapid growth of urbanization significantly influences local atmospheric conditions and life quality of residents living in urban areas by creating a localized phenomenon known as an urban heat island. Urban heat island characteristics are strongly formed by prevailing atmospheric conditions influencing their magnitude and intensity. In this study, we used the Weather Research and Forecasting model to investigate the effects of different airmass and windspeed characteristics on the diurnal cycle of the urban heat island phenomenon during four real weather situations presenting typical scenarios with clear sky conditions. The scenarios consisted of warm dynamic and non-dynamic situations and cold dynamic and non-dynamic situations identified with respect to temperature profiles, humidity and wind speed. The comparison of urban heat island intensity between all four scenarios showed a significant effect of wind speed on urban heat island characteristics and intensity as well as the role of humidity and airmass temperature in diurnal changes. The results showed that urban heat island is best defined by conditions with strong radiative heating and weak wind speed regardless of temperature. Air humidity appears to have significant influence on UHII with cold non-dynamic situations in dry air showing a very high UHII amplitude during the daylight period and high intensity during the night. The comparison of warm and cold dynamics situations showed the influence of vertical heat exchange with strong mixing of air between near-surface levels and lower levels of the troposphere with a mild effect on UHII during the warm situation and strong influence on decreasing UHII during the cold scenario.

Long-term High Resolution Image Dataset of Antarctic Coastal Benthic Fauna

Antarctica is a remote place, the continent is covered by ice and its surrounding coastal areas are frozen for the majority of the year. Due to its peculiarity the observation of the underwater organisms is particularly difficult, complicated by logistic factors. We present a long-term dataset consisting of 755 images acquired by using a non-invasive, autonomous imaging device and encompassing both the Antarctic daylight and dark periods, including the corresponding transition phases. All images have the same field of view showing the benthic fauna and part of the water column above, including fishes present in the monitored period. All the images are manually annotated after a visual inspection performed by expert biologists. The extended monitoring period and the annotated images make the dataset a valuable benchmark suitable for studying the dynamics of the long-term Antarctic underwater fauna as well as for developing and testing algorithms for automated image analysis focused on the recognition and classification of the Antarctic organisms and the automated analysis of their long-term dynamics.

Influence of Different Growth Conditions on Saponarin, Water-Soluble Vitamins, and Mineral Content of Barley Sprouts Cultivated in Chamber System

Barley sprouts contain various secondary metabolites such as polyphenol, policosanol, and γ-aminobutyric acid (GABA). In particular, saponarin, which accounts for about 72% of polyphenols, is well known for antioxidant, anti-inflammatory, and liver function protection effects. Saponarin is greatly affected by environmental conditions such as light, temperature, and moisture. However, there is a lack of studies about the effect of the microclimatic environment on saponarin content in barley sprouts. This study was conducted to evaluate the influence of daily temperature range, light intensity, and light period on saponarin, water-soluble vitamins, and minerals content in barley sprouts. Seeds of Hordeum vulgare L. were sown on a plastic box and cultivated in growth chambers with different conditions by adjusting daily temperature range (DT, 0 → 10°C), light intensity (LI, 120 → 180 µmol m-2 s-1), and light period (LP, day 12 hours → day 18 hours). The plants were harvested when the leaf length reach 15 cm. The fresh weight was not significantly different between each treatment, yet the growth period was highest in barley sprouts cultivated with DT. Saponarin content was higher in DT, LI and LP than control, and highest saponarin content in DT. In contrast, vitamin C content was highest in control and lowest in DT. Similarly, vitamin B1 and B5 content showed the highest in control. Changes in light and temperature elevated saponarin content in barley sprouts, especially daily temperature range showed a dramatic increase. However, the change in daily temperature range affects an increase in growth period and a decrease in vitamin C content. In conclusion, daily temperature range is the predominant environmental factor to produce saponarin-enriched barley sprouts.Different response of saponarin and vitamin C in barley sprouts to change in daily temperature range.

SUN HATS FOR BAT BOXES: MITIGATING THE RISK OF OVERHEATING AT NORTHERN LATITUDES

At northern latitudes, bats often use roosting structures provided by people. Conventional thinking suggests that bat boxes should be entirely black to absorb heat and assist bats with thermoregulation. However, with long periods of summer daylight in subarctic Canada, we suspected that risk of overheating might occur in black boxes. We investigated whether roost temperatures exceeded 42°C, the upper limit of the thermoneutral zone in Little Brown Myotis (Myotis lucifugus), and whether replacing the black roof with a white one, akin to a sun hat, would alleviate the risk of overheating without compromising roost temperatures especially at night. We also investigated whether bats used the boxes. The internal temperature of black boxes exceeded 42°C on some days in 2 summers. Substituting the black roof with a white one consistently reduced the maximum daily roost temperature to below 42°C, but this was also accompanied by a slightly lower minimum roost temperature at night and a cooler roost temperature regime overall. The reduction in maximum daily roost temperature by the white roof was more pronounced on days with higher maximum daily ambient temperatures. At 5 sites with paired white-roof and black-roof boxes, 4 had bat use of both boxes and 1 had no use of either box. Bats used 10 of 19 (53%) black-roof boxes in 2019, and 16 of 21 (77%) in 2020. Replacing a black roof with a white one can mitigate risk of overheating for boxes in subarctic latitudes, and likely through a range of temperate latitudes. However, completely black boxes are still necessary to enhance the thermal environment for roosting bats through most of the summer. We suggest that providing bats with roosting options, such as paired black-roof and white-roof boxes immediately adjacent to one another, is a better habitat enhancement option than just single black boxes.

Impacts of artificial light at night on the vegetative growth and yield attributes of fodder oat (Avena sativa)

Aim: The present investigation was designed to study the impact of artificial light at night on the phenological phases and yield contributing traits of fodder oat variety Kent for holistic breeding along the roadsides or highways. Methodology: The experiment was conducted at Central Research Farm of ICAR-IGFRI, Jhansi, India, in a plot under natural conditions. The treatment Lc (controlled) was under natural conditions receiving normal daylight and dark periods. However, treatment L1 (300-350 lux), L2 (200-300 lux), L3 (100-200 lux), and L4 (10-50 lux) were different light affected areas having distances 0, 5, 10, and 15 m from the light source. Duncan's test, OPSTAT, and SPSS version 16.0 software were used for statistical analysis. Results: The vegetative growth parameters such as plant height, total leaf area, flag leaf area, days to 50% flowering, panicle length, total dry biomass, and test weight were increased linearly as the distance increased from the artificial light source (minimum value for L1 treatment and maximum for Lc). However, plant population per meter square was maximum for L1 treatment and minimum for local control (Lc; no night light effect). Moreover, it is the first report of artificial light at night on the fodder oat from India and concluded that night light significantly affects the plant phenology and yield potential, and opens a new research paradigm on plant-artificial light at night interactions. Interpretation: Plants close to the light source received maximum intensity of night light (L1) than distantly located treatments (L2, L3, and L4). Artificial light at night-time had adverse effects on the yield-contributing traits and showed a significant negative relationship. Key words: Artificial light, Fodder oat, Light intensity, Morphological traits, Night time

Explicit memory, anxiety and depressive like behavior in mice exposed to chronic intermittent hypoxia, sleep fragmentation, or both during the daylight period

Obstructive sleep apnea (OSA) is a chronic and highly prevalent condition characterized by chronic intermittent hypoxia (IH) and sleep fragmentation (SF), and can lead to a vast array of end-organ morbidities, particularly affecting cardiovascular, metabolic and neurobehavioral functioning. OSA can induce cognitive and behavioral and mood deficits.Male C57Bl/6J 8-week-old mice were housed in custom-designed cages with a silent motorized mechanical sweeper traversing the cage floor at 2-min intervals (SF) during daylight for four weeks. Sleep control (SC) consisted of keeping sweeper immobile. IH consisted of cycling FiO2 21% 90 seconds-6.3% 90s or room air (RA; FiO2 21%) for sixteen weeks and combined SF-IH was conducted for nine weeks. Open field novel object recognition (NOR) testing, elevated-plus maze test (EPMT), and forced swimming test (FST) were performed.SF induced cognitive NOR performance impairments in mice along with reduced anxiety behaviors while IH induced deficits in NOR performance, but increased anxiety behaviors. SF-IH induced impaired performance in NOR test of similar magnitude to IH or SF alone. Combined SF-IH exposures did not affect anxiety behaviors.Thus, both SF an IH altered cognitive function while imposing opposite effects on anxiety behaviors. SF-IH did not magnify the detrimental effects of isolated SF or IH and canceled out the effects on anxiety. Based on these findings, the underlying pathophysiologic processes underlying IH and SF adverse effects on cognitive function appear to differ, while those affecting anxiety counteract each other.

Selection of stevia elite genotypes aiming at the development of cultivars adapted to the Brazilian Savanna

In this work, the objective was to evaluate morphoagronomic traits, correlate and select elite genotypes of Stevia rebaudiana (Bert.) Hemsley with high productivity, and adapted to Brazilian Savanna conditions. A total of 230 genotypes were evaluated, from the Embrapa Cerrados Working Collection, from 2018 to 2019, with 24 evaluations, carried out in six cuts, with each cut representing a certain moment of generation of the response data of the analyzed genotypes. Four traits were analyzed: green biomass production (g), plant height (cm), tillering number and juvenile period of each individual. The means of the characteristics of each genotype were correlated according to Pearson's correlation coefficient. The Mulamba and Mock index was applied, with a selection intensity of 10%, to choose the superior genotypes. There are high positive correlations between juvenile period, height and green biomass production. The selected population were 23 superior genotypes, based on the application of rank sum resulting in high selection gains for the traits of interest. Finally, the selection of elite stevia genotypes with high production of green biomass, greater insensitivity to length of the daily light period, as well as taller plants, are essential for the continuity of the stevia breeding program on the Brazilian Savanna.

Cardiovascular regulation in female students of northern university during extreme photoperiod seasons

Objective. The aim of study was to assess the state of cardiovascular system in female students in the northern region during the seasons with extreme photoperiod. Design and methods. The study was conducted in Nizhnevartovsk, Khanty-Mansi Autonomous Okrug-Yugra (a region equated to the Far North) in the seasons with extreme values of photoperiod. The female students of Nizhnevartovsk State University (n = 73) aged 18-21 years were examined. Anthropometric measurements were carried out. Systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) were recorded automatically using UA-101 model tonometer. Pulse and mean dynamic pressure were calculated according to Hickam's formula. On the basis of HR we determined the average duration of cardiac cycle. Autonomic tone was assessed according to calculated Kerdo index (KI). We used CardioVisor-06c to determine the prenosological state of cardiac activity. Results. There was a significant increase in body weight in the short daylight period. The HR during the long daylight period was significantly higher than during light deprivation, leading to a shorter cardiac cycle duration. Seasonal dynamics of blood pressure characteristics were not evident, although during “white nights” at least 10 % female students had SBP higher than 130 mm Hg, and maximal SBP reached 135 mm Hg. KI values demonstrated significant changes in autonomic tone. During short daylight hours average characteristics of KI were negative and reflected activity of parasympathetic activity. Increase of sympathetic influences was during longer daylight hours. During “biological twilight” “Myocardium” index was significantly lower than during white nights. During short daylight hours only 10 % students showed “Myocardium” index over normal values (15 %), while half of respondents had higher values during white nights. “Rhythm” index was normal during the short daylight hours and significantly higher during the long daylight hours, only 10 % participants had normal values. Conclusions. The analysis of electrophysiological parameters of myocardium showed seasonal changes in female students and “white nights” were associated with more negative effects than “biological twilight”. During “white nights” we showed increase in integral indices of dispersion mapping, increase in resting HR and KI.

Decisive Climatic Factors for Production of Bioactive Saponarin-Rich Barley Sprouts: A Study of Seasonal Effect

Saponarin content in barley sprouts may vary greatly with environmental conditions, such as climate, leading to difficulty in uniformly producing saponarin-rich barley sprouts in situ farmlands throughout the year. This research was an early attempt to identify the optimal conditions of various climatic factors, such as temperature, light, and humidity according to seasonal change, for maximizing the saponarin content of sprouted barley through the two-year field experiment. As a result, the growth index, as leaf length relative to growth period, of barley sprouts varied greatly with sowing time, and they tended to decrease with an increase in the ambient temperature, such as average daily temperature. In contrast, higher saponarin contents were observed in the sprouts collected in March, April, September, and October than those collected from May to August. We also found significantly positive correlations of saponarin content with daily temperature range and average light period, indicating that they could be decisive climatic factors for the production of barley sprouts with a higher saponarin content. Interestingly, the polynomial relationship between saponarin yield and leaf length showed the highest yield with 2.18 mg plant−1 at 15.9 cm in length, suggesting a best cutting time for the production of saponarin-rich barely sprouts based on the leaf length. Overall, the decisive climatic factors according to seasonal change for saponarin biosynthesis may be considered to be daily temperature differences and light hours.

Foraging Oxaea flavescens bees as a function of the dynamics of abiotic factors and food resource availability from Styrax camporum flowers

We examined the abiotic factors and co-specific competition for food resources that regulate the foraging activity of Oxaea flavescens bees on Styrax camporum flowers. Foraging records were gathered during 20 min. periods at the beginning of each hour between 05:00h and 18:00h during three nonconsecutive days. Pearson correlation and linear regression tests indicated that the foraging activity of O. flavescens was associated with abiotic factors during the day. O. flavescens represented 89.9% of the observed foraging visits to S. camporum flowers. On the first day of sampling, when environmental conditions were stressful, the foraging activity of O. flavescens was significantly negatively correlated with light intensity, wind speed, and temperature, and positively correlated with relative humidity. Under those conditions, optimal foraging was little affected by the availability of floral resources. On the second and third days, however, when environmental conditions were more favorable, the principal limiting factor of O. flavescens foraging activity was nectar depletion. The maximum peak of foraging under those conditions occurred before the abiotic conditions were fully favorable, however, as the eventual depletion of floral resources resulted in unfavorable cost/benefit implications for foraging during the otherwise most adequate daylight period.

First report of triterpenes pathway in Calotropis procera revealed to accumulate beta-amyrin

The major reports on Calotropis procera (C. procera) indicated the importance of this plant as a resource of pharmaceutically active ingredients as well as its medical advantages. β-amyrin (BA) is a significant substance in this plant and has a pharmacological effects in some frameworks, like focal and fringe sensory system, digestive and immune systems. In this study, the impact of sunlight before and after irrigation on the BA production in C. procera is studied its pathway with involved eight key enzymes. The eight enzymes' genes were characterized and successfully submitted to NCBI; AAS (acc.no. KU997645) for α-amyrin synthase, BAS (acc.no. MW976955) for β-amyrin synthase, SE (acc.no. MW976956) for squalene epoxidase, SS (acc.no. MW976957) for squalene synthase, GPPS, (acc.no. MW976958) for geranyl pyrophosphate synthase, FPPS (acc.no. MW976959) for farnasyl pyrophosphate synthase, CAS1, (acc.no. MZ00598) for cycloartenol synthase1 and LS (acc.no. MZ005982) for lupeol synthase. qRT-PCR analysis revealed high expression levels of GPPS, FPPS, SS, SE, and BAS genes at all times specially midday. Otherwise, CAS1, LS and BAS expression levels were very low at all daylight periods. The UPLC β-amyrin data are in accordance with qRT-PCR results. This indicates that triterpenes biosynthetic pathway in C. procera is going to β-amyrin accumulation with the highest level at midday.

Daytime, tidal amplitude and protected areas influence movements and habitat use on mudflats of wintering black-tailed godwits

Understanding environmental factors underlying animal foraging distribution is of major importance in defining priority conservation actions. During their wintering stage, most shorebirds depend on intertidal areas, as foraging grounds, and on supratidal areas, as high tide roosts. The accessibility of foraging areas and food resources is thus limited, and most wintering shorebirds have to forage whenever mudflats are available, both day and night, to fulfil their daily energetic demands. However, current knowledge of shorebirds’ spatio-temporal use of foraging habitats is often restricted to the daylight period. In that context, we investigated the spatial distribution and habitat selection of wintering black-tailed godwits Limosa limosa islandica, during both the day and night, and in relation to the environmental characteristics. We equipped wintering black-tailed godwits at two different sites on the Pertuis Charentais (Atlantic French coast) with miniaturised GPS loggers. We then tested the hypothesis that godwits feed both during day and night, and show contrasting foraging behaviours and distribution in response to different visual capacities, prey availability, predation risks and human activities. The selection of feeding areas was highly variable according to nycthemeral periodicities, with little change in the habitat types selected. The estimated nocturnal surface of feeding areas were two times smaller than daytime ones, and located closer to the coastline. Moreover, birds largely foraged inside protected areas during the daytime, while most of them foraged outside at night. Finally, godwits with the smallest feeding home ranges stayed inside the Nature Reserves, during both day and night, while the others prospected outside the protected areas more often, preferentially at night.

Ultra-light photosensor collars to monitor Arctic lemming activity

BackgroundStudying the anti-predatory behavior of mammals represents an important challenge, especially for fossorial small mammals that hide in burrows. In the Arctic, such behaviors are critical to the survival of lemmings considering that predation risks are high every summer. Because detailed information about how lemmings use burrows as hideouts is still lacking, we developed a 1.59 g photosensitive collar to record any event of a small mammal moving between a dark area (e.g., burrow) and a bright area (e.g., outside the burrow). Tests of how collars affected lemming behavior were conducted in captivity in Cambridge Bay, Nunavut, Canada, in November 2019 and field tests were conducted on Bylot Island, Nunavut, Canada, in August 2021.ResultsThe device was made of two chemical batteries and a printed circuit board (PCB) equipped with a photosensor and a real-time clock that recorded amplitude transient thresholds of light (lux) continuously. In accordance with ethical use of such devices, we verified that no abnormal loss of body mass was observed in captive or free-ranging lemmings, and no difference in recapture rates were observed between those with and without a collar, though we could not test this for periods longer than 108 h. Measurements of light intensities revealed consistent patterns with high lux levels at mid-day and lowest during the night. Lemmings showed clearly defined behavioral patterns alternating between periods outside and inside burrows. Despite 24-h daylight in the middle of the summer, August nighttime (i.e., 11 PM to 4 AM) lux levels were insufficient for amplitude transient thresholds to be reached.ConclusionBy taking advantage of the long periods of daylight in the Arctic, such technology is very promising as it sets new bases for passive recording of behavioral parameters and builds on the prospect of further miniaturization of batteries and PCBs.

Growth, nitrate uptake kinetics, and biofiltration potential of eucheumatoids with different thallus morphologies.

The declining production of commercially important eucheumatoids related to serious problems, like increasing susceptibility to ice-ice disease and epiphytism, may be ameliorated by nutrition. This ushered an increasing interest in incorporating seaweeds into an integrated multi-trophic aquaculture (IMTA) setup to take up excess inorganic nutrients produced by fish farms for their nourishment. In this regard, it is important to understand the nutrient uptake capacity of candidate seaweeds for incorporation into an IMTA system. Here, we examined the growth, nitrate ( ) uptake kinetics, and biofiltration potential of Eucheuma denticulatum and three strains of Kappaphycus alvarezii (G-O2, TR-C16, and SW-13) with distinct thallus morphologies. The uptake rates of the samples were determined under a range of concentrations (1-48 µM) and uptake rates were fitted to the Michaelis-Menten saturation equation. Among the examined eucheumatoids, only SW-13 had a linear response to concentration while other strains had uptake rates that followed the Michaelis-Menten saturation equation. Eucheuma denticulatum had the lowest Km (9.78 ± 1.48 µM) while G-O2 had the highest Vmax (307 ± 79.3 µmol · g-1 · min-1 ). The efficiency in uptake (highest Vmax /Km and α) was translated into the highest growth rate (3.41 ± 0.58% · d-1 ) measured in E. denticulatum. Our study provided evidence that eucheumatoids could potentially take up large amount of and fix CO2 when cultivated proximate to a fish farm as one component of an IMTA system. During a 45 -d cultivation period of eucheumatoids, as much as 370 g can be sequestered by every 1 kg initial biomass of E. denticulatum growing at 3% · d-1 . Furthermore, based on our unpublished photosynthetic measurements, the congeneric K. striatus can fix 27.5 g C · kg-1 DW during a 12 h daylight period.

Controlled Mass Rearing of Cochineal Insect (Hemiptera: Dactylopiidae) Using Two Laboratory-Scale Production Systems in Peru.

The carmine cochineal (Dactylopius coccus Costa) has high economic value as it is a natural source of carminic acid, an organic chromophore used in a wide range of sectors including pharmaceutics, food, and cosmetics. High demand is fuelling the search for innovative production techniques in order to move away from dependence on the prickly pear, which carries a number of limitations. The aim of this study was to establish cochineal colonies and breed and mass-produce the insects using two laboratory-scale production systems. The first system (STC-01) comprised a prismatic acrylic box with three compartments; synthetic matrices were placed vertically inside the box to provide support and a source of nutrients for the cochineal, and the system was lit artificially during fixed daylight periods. The second system (STC-02) comprised an automated micro-tunnel allowing the insects to move towards the sunlight, containing synthetic matrices arranged horizontally. There was a significant difference in yield between the two systems in a cochineal total life cycle of 120 d (80–90 d harvest period in both cases), with STC-01 being superior and producing a maximum yield of 4.86 ± 0.68 g fresh weight per day per square metre compared with 3.20 ± 0.14 g fresh weight per day per square metre production yield in STC-02. We conclude that cochineal production under controlled artificial conditions is feasible and sustainable, removing the need for natural and biological support and overcoming the environmental limitations posed by traditional production methods.

Behavior of domestic pigs under near-natural forest conditions with ad libitum supplementary feeding

Today's livestock agriculture faces major changes in domestic pig husbandry—besides animal health and productivity, aspects of animal welfare and animal-friendly husbandry systems for pigs increasingly gain attention. To get a basic and current overview of the behavior of pigs in a near-natural habitat, we studied two groups of 20 domestic fattening pigs kept in two free-range forest enclosures in southern Germany. The pigs had ad libitum access to supplementary concentrate feed (CF), green fodder (GF), water and shelters. During the 6-month observation period, we found that the pigs showed no biphasic activity rhythm. The activity phase began at ca. 05:15 and ended at 21:00 in summer, and it shortened in winter. The peak of activity was between 14:00 and 18:00. The individual behaviors were assessed on 16 observation days during three direct-observation-intervals each (morning: 08:00 to 10:00; midday: 12:00 to 14:00; evening: 16:00 to 18:00). In the course of a day, some of the occurring behaviors such as rooting and locomotion continually increased from morning to evening. In contrast, resting occurred the least in the evening. Feed and water uptake were observed without noticeable influence of the daytime during the entire daylight period. Despite ad libitum availability of CF and GF at the feeding place, the pigs spent only about 13% of the observation time eating (including food uptake in the forest), with the total time and average duration being greater for GF than for CF uptake. Furthermore, the pigs spent about 24% of the time rooting. Thus, rooting seems to be an essential behavior of domestic pigs without the primary motivation of hunger. Resting made up 47% of the total observation time. The remaining 16% of the observation time was spent with several short-lasting active behaviors, such as interacting with the environment, locomotion, playing and comfort behavior. Based on the results of our study, we provide recommendations for adequate management practices in modern, animal-friendly pig stalls and free-range enclosures.

Can Annual Daylight Cycles and Seasons Have an Effect on Male Sexual Functions?

IntroductionMammals’ sexual functions exhibit seasonal variations that have been attributed to changes in the daylight. In this study, taking into consideration endocrine and psychogenic status, we aimed to investigate whether human males experience changes in erectile functions and sexual desire depending on daylight periods and seasons, and whether periodicity exists in human sexual behavior.Materials and methodsInternational Index of Erectile Function (IIEF) and psychiatric scale scores of 221 male patients were evaluated. In addition, hormonal parameters of the patients were examined. These data were first evaluated in two groups (summer and winter) according to local daylight amounts the participants received. Then IIEF scores were also analyzed according to four conventional seasons (winter, spring, summer, and autumn).ResultsThere was no significant difference in laboratory data, psychiatric scale scores and IIEF evaluations between summer and winter groups. Moreover, no significant difference was found in terms of sexual desire and erectile functions in terms of four seasons (p > 0.05).ConclusionAccording to the results of this study, there is no periodicity in human sexual functions both in relation to daylight and four seasons.

Suppression of red color development associated with anthocyanin accumulation in the epicarp of grape (Vitis labrusca × vinifera cv. Ruby Roman) berries caused by air temperature in daylight periods higher than 33°C during maturation

The effect of high air temperature on the anthocyanin accumulation in the epicarp of 'Ruby Roman' grape (Vitis labruscana × vinifera) berries was examined. Seventeen types of anthocyanin were detected from the epicarp tissue of the matured berries using HPLC. Since a strong positive correlation (P < 0.005, R2 = 0.937) was confirmed between the degree of color density evaluated using a color chart and the total content of anthocyanins quantified separately, it seems possible to trace anthocyanin accumulation using the color chart on each berry during maturation at different air temperatures. Four conditions were designed for cooling the fruit clusters with a spot-cooling system, which can keep air temperature 4–5°C lower for 60–70 days after the full–bloom, i.e. consecutive (0:00–24:00) cooling, daytime (6:00–18:00) cooling, nighttime (18:00–6:00) cooling and no–cooling (control). The degree of color density showed statistically higher (P < 0.05) values in the consecutive–cooling treatment than that of the control through the post–cooling duration (0–15 days after cooling). To clarify the effect of temperature zones with or without daylight on the anthocyanin accumulation in the epicarp, percentage of exposure time to each temperature zone of < 21, 21–24, 24–27, 27–30, 30–33, 33–36 and 36°C ≤ were calculated for both daylight and dark periods, separately. Correlations of the ∆ time% (the amount of difference in percentage of exposure time from the control) with the ∆ color degree (the amount of difference in degree of color density from the control) in the daylight period were positive at temperature zones of < 30°C, but turned to negative at those of 30°C ≤. The fact that correlation coefficient was statistically significant (P < 0.05) at the temperature zones of 27–30°C (positive) and 33–36°C (negative) in the daylight period shows that the threshold where the anthocyanin accumulation starts to be suppressed exists within 30–33°C.

Circadian and Seasonal Patterns of Body Temperature in Arctic Migratory and Temperate Non-migratory Geese

Arctic migration presents unique challenges to circadian physiology. In addition to the metabolic cost of maintaining a relatively high body temperature (Tb) above ambient temperature, migratory birds are also exposed to rapidly changing light conditions as they transition between light-dark cycles and a 24-hour polar day. A previous study suggested that Arctic-migratory barnacle geese (Branta leucopsis) may utilise adaptive heterothermy (i.e., a controlled decrease in core Tb) during and around the autumn migratory period in order to minimise the metabolic cost of migration, but the impact of seasonally changing daylight conditions on other parameters of the circadian profile of Tb in these geese remained obscure. Here, we provide a detailed comparative analysis on the circadian rhythm of Tb and its seasonal development in free-living barnacle geese from three study populations that differ in their migratory behaviour and in the environments they occupy. We recorded abdominal Tb in non-migratory geese from a temperate breeding colony in Netherlands and in migratory geese from a colony in the Russian low Arctic, and analysed these data together with previously published Tb data on geese from a migratory colony in the high Arctic of Svalbard. We found that the circadian Tb profile in the barnacle goose was well aligned with the daily and seasonally changing daylight conditions. In the migratory populations, a fast re-entrainment of the rhythm and its phase was observed when zeitgeber conditions changed during migratory movements. The circadian rhythmicity of Tb was lost once the geese encountered permanent daylight at their northern staging and breeding sites. Circadian Tb rhythmicity was re-established when the period of permanent daylight ended, at rates corresponding to rates of seasonal changes in daylength in the high and low Arctic. Although our data corroborated findings of a decrease in daily mean Tb before autumn migration in both migratory populations in this study, the pre-migratory decrease in Tb was less drastic than previously reported. Moreover, in contrast to previous study, the decrease in Tb stopped at the onset of migration. Overall, our data reveal no evidence that heterothermy in the barnacle goose is functionally linked to migration.