Short-day Period Research Articles

Stability of immunohaematological reagents used for blood typing of recipients in the tube technique.

The storage temperature of immunohaematological reagents generally ranges from 2 to 8°C, and they should be utilised at room temperature. This study aimed to analyse the stability of immunohaematological reagents used in ABO and RhD typing. The evaluation encompassed the potency, specificity, and integrity of anti-A, anti-B, anti-D, RhD control sera, and A1 and B red blood cells (RBC) reagents after long (8 h) and short (4 h) daily periods of exposure to room temperature (20-24°C), 5 days a week for 4 weeks. Additionally, the A1 and B RBC reagents were exposed daily for 11 h and 30 min at room temperature, including 30 more minutes at room temperature with simultaneous homogenisation through equipment. For the control, an aliquot of each reagent was constantly stored at refrigeration temperature, while another was exposed to room temperature for 12 h daily. Tests conducted included reaction intensity, titration, and avidity for antisera, reaction intensity, free haemoglobin determination, and electrical conductivity for the RBC reagents. The antisera maintained the reaction intensity. The titre and avidity of the antisera satisfied the minimum Brazilian requirements after different exposure periods. A higher free haemoglobin concentration was noted in the RBC reagents subjected to room temperature and simultaneous homogenisation, although this did not affect the potency and specificity. The electrical conductivity average of the RBC reagent remained consistent. The findings indicate that the immunohaematological reagents from a specific manufacturer are stable under the tested temperature, ensuring the quality of the results under these conditions.

Effect of photoperiod on the DNA, RNA and protein concentration in the silkgland of tasar silkworm, Antheraea mylitta (D) (Lepidoptera, Saturniidae)

In Antheraea mylitta (D) (Lepidoptera, Saturniidae), the effect of photoperiod on total DNA, RNA, and protein concentration in the middle silk gland (MSG) and posterior silk gland (PSG) was studied. The photoperiod caused enhancement in the secretory activity and stimulates the sericogenesis process in MSG and PSG. The total nucleic acids and protein concentration of MSG and PSG under 24L:00D condition reached maximum level and then it decreased. Maximum nucleic acids and protein concentration were observed during long-day period and the minimum during short-day period. The photoperiod activated or inhibited the biological clock which acted upon the respective endocrine glands accordingly and control the process of sericogenesis. The larvae underwent significant changes with high DNA, RNA and protein concentration under 24L:00D, which is highly suitable for the silk protein synthesis.

Effect of dietary supplementation with algae extracts on growth performance and caecal microbiota of broiler chickens

ABSTRACT 1. The objective of this study was to test the dose response of dietary supplementation with algae extracts rich in marine-sulphated polysaccharides (MSP1 and MSP2) on the growing performance, body composition at slaughter and caecal microbiota of broiler chickens. 2. Male broiler Ross 308 chicks 1-d-old were distributed into eight groups, a control group (unsupplemented), four groups supplemented with increasing doses of algae extract MSP1 (40, 81, 121 and 162 g/ton feed) and three groups supplemented with increasing doses of algae extract MSP2 (40, 81 and 162 g/ton feed). Each group comprised six pens of 56 chickens. 3. All chickens were reared under challenging conditions, i.e. high rearing density of 42 kg/m2, fed growing and finishing diets containing, palm oil, rye and high levels of wheat and subjected to short daily fasting periods. The growth performance was recorded during rearing. At 10, 22 and 31 d of age, 12 chickens per group were euthanised to collect the caecal contents and determine microbiota composition and short-chain fatty acid levels. At d 35, the quality of litter and the condition of feathers, footpads and tarsals were scored. At d 36, 7 chickens per pen were slaughtered under commercial conditions to determine carcass composition and breast meat quality (ultimate pH and colour). 4. Algal extract MSP1 increased the weight of the caeca and butyrate concentration in the caeca at d 22 (p ≤ 0.05). It increased the ultimate pH of breast fillet measured after slaughter at d 36 (p ≤ 0.05). Moreover, the group receiving 162 g/t MSP1 had a more diverse microbiota at d22. However, algal extract MSP2 had negligible effect on the different measured parameters.

Sex-specific heterothermy patterns in wintering captive Microcebus murinus do not translate into differences in energy balance

The physiological mechanisms of responses to stressors are at the core of ecophysiological studies that examine the limits of an organism's flexibility. Interindividual variability in these physiological responses can be particularly important and lead to differences in the stress response among population groups, which can affect population dynamics. Some observations of intersexual differences in heterothermy raise the question of whether there is a difference in energy management between the sexes. In this study, we assessed male and female differences in mouse lemurs (Microcebus murinus), a highly seasonal malagasy primate, by measuring their physiological flexibility in response to caloric restriction and examining the subsequent impact on reproductive success. Using complementary methods aiming to describe large-scale and daily variations in body temperature throughout a 6-month winter-like short-day (SD) period, we monitored 12 males and 12 females, applying chronic 40% caloric restriction (CR) to 6 individuals in each group. We found variations in Tb modulation throughout the SD period and in response to caloric treatment that depended on sex, as females, regardless of food restriction, and CR males, only, entered deep torpor. The use of deeper torpor, however, did not translate into a lower loss of body mass in females and did not affect reproductive success. Captive conditions may have buffered the depth of torpor and minimised the positive effects of torpor on energy savings. However, the significant sex differences in heterothermy we observed may point to physiological benefits other than preservation of energy reserves.

Data collected by citizen scientists reveal the role of climate and phylogeny on the frequency of shelter types used by frogs across the Americas

Shelters are microhabitats where animals rest and hide. These microhabitats can be used from short daily periods to long-term estivation or hibernation. Environmental conditions and the phenotypical characteristics of the animal drive habitat selection in relation to shelters. Based on this, climate regions and phylogeny are expected to affect the use of different shelter types. Although shelters are yet to be described for most anuran species, a variety of microhabitats have already been reported as shelter-sites, including dense vegetation, rock crevices, and holes in the ground. In this study, we evaluated photos of frogs for sheltering behaviour from 29 countries in the Americas deposited on the popular citizen-science platform, iNaturalist. We compared the frequency of use of different shelter types identified on the photos among different climate regions and anuran families, also testing possible phylogenetic signals. We identified 11,133 photographs of 378 frog species showing individuals hiding in shelters or in a resting position. We classified observations into 10 shelter types, with live vegetation (24.7 %) being the most commonly recorded natural shelter, followed by hole in the ground (11.4 %) and tree trunk (11.1 %). The use of different shelter types varied between arid and humid climates, and also among different anuran families. We found strong phylogenetic signal for three shelter types (hole in the ground, live vegetation, and water) and the differences in shelter use among taxa suggest a relation with body characteristics. Approximately 47 % of observations of threatened and near threatened species were in hole in the ground, while artificial habitat represented only 3.6 % of the observations in this group. The daily pattern of shelter use corroborated the nocturnal activity of most species. Our findings also expanded the description of shelter sites for 330 species that had no published information on this behaviour. This study contributes to our current knowledge about animal behaviour and highlights the use of citizen science as an effective approach to understand the natural history of amphibians at a large scale.

Seasonal reproduction and gonadal function: a focus on humans starting from animal studies.

Photoperiod impacts reproduction in many species of mammals. Mating occurs at specific seasons to achieve reproductive advantages, such as optimization of offspring survival. Light is the main regulator of these changes during the photoperiod. Seasonally breeding mammals detect and transduce light signals through extraocular photoreceptor, regulating downstream melatonin-dependent peripheral circadian events. In rodents, hormonal reduction and gonadal atrophy occur quickly and consensually with short-day periods. It remains unclear whether photoperiod influences human reproduction. Seasonal fluctuations of sex hormones have been described in humans, although they seem to not imply adaptative seasonal pattern in human gonads. This review discusses current knowledge about seasonal changes in the gonadal function of vertebrates, including humans. The photoperiod-dependent regulation of hypothalamic-pituitary-gonadal axis, as well as morphological and functional changes of the gonads is evaluated herein. Endocrine and morphological variations of reproductive functions, in response to photoperiod, are of interest as they may reflect the nature of past population selection for adaptative mechanisms that occurred during evolution.

The size of signal detection and emission organs in a synchronous firefly: sexual dimorphism, allometry and assortative mating.

The size of the organs responsible for emitting and detecting sexual communication signals is a likely target for selection. Communication via bioluminescent signals in synchronous fireflies is a promising model to test hypotheses regarding differences between males and females in the effect of the size of signal emission and detection organs on fitness components. Synchronous firefly species congregate in large numbers during the mating season, displaying bioluminescent signals aimed at potential mates during relatively short nightly periods. Operational sex ratios are male-biased and, thus, the so-called typical sex roles (indiscriminate males and choosy females) are expected to evolve. We studied the synchronous firefly Photinus palaciosi, a species that during the mating season congregates in forests of central Mexico offering a magnificent natural show that attracts numerous tourists. P. palaciosi females have reduced wings (brachyptery) and cannot fly. Our field study tested the hypothesis that the male-biased operational sex ratio and the short daily mating period result in strong male-male competition that selects for males with larger lanterns and larger eyes, and against male mate choice, whereas female-female mate competition is absent and, thus, no selection on lantern or eye size is expected. Even though lantern, eye or body size do not predict the probability of being found in copula for either sex, sexual dimorphism in these features, along with allometric slopes of lantern size and assortative mating in terms of relative lantern size, support not only the hypothesis of intense sexual selection among males, but the possibility of subtle mechanisms of sexual selection among females. Trade-offs between investment in signaling (lanterns) versus detection (eyes) structures, or with pressures different from sexual selection such as those imposed by predators, are also likely to be important in shaping the evolution of sexual signaling in these fireflies.

Yield stability and adaptability of kenaf (Hibiscus cannabinus L.) genotypes at different kenaf growing regions in Indonesia

Stability and adaptability analysis is a very important tool for breeders to find out the potentiality of a genotype in various environments. Twenty kenaf genotypes were evaluated in 6 locations, namely Asembagus (Situbondo Regency), Muktiharjo (Pati Regency), Sumberrejo (Bojonegoro Regency), Laren (Lamongan Regency), Wanareja (Cilacap Regency), and Sukolilo (Pati Regency). For Asembagus, Muktiharjo, and Sumberrejo testing was carried out in 2013 for 2 seasons, namely longday and shortday period, while testing in Laren, Wanareja, and Sukolilo carried out in 2014 for one season on a longday period. The study is to determine the effect of the environment on the fiber yield of kenaf genotypes and their adaptation in various environments. The results of variance analysis showed that genotypes, environment, and genotype by environment interactions had a very significant effect on the fiber yield of kenaf. The average fiber yield of kenaf ranges from 0.846 to 3.758 tons per ha. Regression coefficients and mean square of deviation from regressions differ from each other indicating that there are variations in stability and adaptability between genotypes tested.

Làm mất ảnh hưởng của quang kỳ trên giống lúa Nàng Thơm Chợ Đào

Traditional rice in the Mekong Delta is only able to flower after exposing to a short-day period due to its photoperiod sensitivity. Therefore, deflecting the photoperiod of these good quality, good adaptability and salinity tolerance seasonal rice varieties is an urgent requirement now, serving production in the saline affected areas in the Mekong Delta. This study was carried out with a traditional rice rice variety: “Nang Thom Cho Dao”, by treating 1,000 seeds at the germination stage at temperature of 500C during 5 minutes. The treated seeds were planted and selected mutant lines from generation M1 to M5 in the greenhouse in the condition alternative long- and short-day lighting time. The results showed that mutant frequency was 2‰, the particle length changed in compared to the original variety (increased by 0.1 to 0.2 mm). Two of mutant rice lines were selected, photoperiod-insensitive, with short duration (

New onion (Allium cepa L.) cultivars for long- and short-day periods

ISHS XXX International Horticultural Congress IHC2018: II International Symposium on Root and Tuber Crops: Value Added Crops for the Next Generation New onion (Allium cepa L.) cultivars for long- and short-day periods

Role of melatonin and circadian rhythms in seasonal reproduction in rams

In the ram, changes in daylength influence testicular activity by modifying the release of luteinizing hormone-releasing hormone (LH-RH) and thus the gonadotrophins. To investigate the nature of this response the hourly fluctuations in the circulating levels of prolactin, luteinizing hormone (LH) and melatonin were measured in rams kept under various artificial lighting conditions. In Exp. 1, 8 Soay rams (4 control and 4 from which the superior cervical ganglia had been removed) were exposed to alternating 16-week periods of short days (8L: 16D) and long days (16L: 8D) for over 2 years, and blood samples were collected hourly for 25 h on two occasions. The lighting regimen resulted in marked testicular and endocrine changes in the controls but not in the ganglionectomized rams which had low or undetectable levels of melatonin (less than or equal to 33 pg/ml) and an unusual diurnal rhythm in prolactin. In Exp. 2, 8 intact Soay rams were exposed to an ahemeral lighting regimen of 8L: 28D for 16 weeks; at the end of this period blood samples were collected hourly for 52 h and assayed for prolactin. During the pretreatment period of long days (16L: 8D), the testes became fully regressed. During the 16 weeks of 8L: 28D, redevelopment occurred, but the growth of the testes was slow compared to that normally occurring under short days of 8L: 16D. The prolactin profiles showed evidence of circadian rhythm in hormone secretion, with a correlation between the timing and duration of the rhythm and the degree of testicular development. These combined results support the idea that the photoperiodic response in the ram involves an interplay between the secretory activity of the pineal gland, and a light/dark entrained circadian mechanism in the brain.

A chronological assessment of foraging activities of the Cotton Pigmy Goose, Nettapus coromandelianus Gmelin, 1789 at Dulahara pond, Ratanpur, Chhattisgarh, India

ABSTRACTThis study was planned to assess the foraging activity of ecological important avian species the N. coromandelianus at Dulahara pond of Ratanpur, Chhattisgarh. In present work we observed the effect of “time of the day” and “photoperiod” on daytime foraging activities of N. coromandelianus. The most applied foraging skills of N. coromandelianus were documented for two repetitive days each for the period of long days (March and April 2015) and short days (December 2015 and January 2016). One-way ANOVA (by SPSS 16.0) was employed to observe the effects of “photoperiod” and “time of the day” on daytime foraging pattern in order to the frequency of foraging techniques. The rhythms in daytime foraging movement were estimated by means of Cosinor rhythmometry at 24 h and 12 h. The current study clarified that the N. coromandelianus mostly applied three main techniques viz., head and neck dipping, diving and striking on which both the diving and striking were the most employed technique while the head and neck dipping was less employed technique during foraging. Moreover, the N. coromandelianus maximally involved for foraging activities during the short day than long day.

Production and quality of three varieties of chrysanthemum grown in pots with different NPK rates

Chrysanthemum can be grown for cutting or as a pot plant year-round, providing a constant production flow. In Brazil, little is known about mineral nutrition and fertilization for this crop. Thus, the objective of this work was to evaluate the production and quality of chrysanthemum varieties cultivated in pots with different NPK rates. The experiment was conducted in a completely randomized design with the NPK rates (10-10-10) of 3 g L-1, 6 g L-1 and 9 g L-1 and chrysanthemum varieties Sheena, Calabria and Indianapolis. Pots of 1.2 L capacity were filled with substrate and placed three cuttings per pot kept in a fog chamber under long days. After 21 days, apical pruning was done and started the short-day period. After flowering induction, short days were suspended. It was realized analysis of variance and it was noticed that stem length and EC were affected by NPK rates. It was observed an inverse relation between the increase in NPK rate and cultivation cycle, resulting in precocity of flowering for all varieties. Plants cultivated under 9 g L-1 rate did not present toxicity symptoms, suggesting that this dose was more adequate for the production of pot plants for all three varieties.

Daylight Savings Time Transitions and the Incidence Rate of Unipolar Depressive Episodes.

Daylight savings time transitions affect approximately 1.6 billion people worldwide. Prior studies have documented associations between daylight savings time transitions and adverse health outcomes, but it remains unknown whether they also cause an increase in the incidence rate of depressive episodes. This seems likely because daylight savings time transitions affect circadian rhythms, which are implicated in the etiology of depressive disorder. Therefore, we investigated the effects of daylight savings time transitions on the incidence rate of unipolar depressive episodes. Using time series intervention analysis of nationwide data from the Danish Psychiatric Central Research Register from 1995 to 2012, we compared the observed trend in the incidence rate of hospital contacts for unipolar depressive episodes after the transitions to and from summer time to the predicted trend in the incidence rate. The analyses were based on 185,419 hospital contacts for unipolar depression and showed that the transition from summer time to standard time were associated with an 11% increase (95% CI = 7%, 15%) in the incidence rate of unipolar depressive episodes that dissipated over approximately 10 weeks. The transition from standard time to summer time was not associated with a parallel change in the incidence rate of unipolar depressive episodes. This study shows that the transition from summer time to standard time was associated with an increase in the incidence rate of unipolar depressive episodes. Distress associated with the sudden advancement of sunset, marking the coming of a long period of short days, may explain this finding. See video abstract at, http://links.lww.com/EDE/B179.

Flowering time regulation in perennial ryegrass

Flowering in perennial ryegrass (Lolium perenne L.) is induced by a period of short days and low temperatures (vernalisation), followed by long-day photoperiod conditions. Genetic linkage mapping and association genetics studies have collectively identified 36 quantitative trait loci for flowering time which were distributed across all seven linkage groups of perennial ryegrass. Close to 40 genes (or putative orthologues/homologues of genes known from other species) for flowering time regulation have been identified, including central integrators and genes involved in four pathways (vernalisation, photoperiod, gibberellin, and autonomous). The structure and function of these predicted genes remains to be characterised. Although the photoperiod pathway is conserved in comparison to that of other temperate grasses, the vernalisation pathway appears to differ, due to absence of an orthologue of the cereal VRN2 gene. Although putative components from the autonomous pathway were identified, their target is unclear. No counterparts of genes from two other pathways (ageing and ambient temperature) have so far been reported. Given that c. 200 genes for flowering time regulation have been described in the model plant species Arabidopsis thaliana (L.) Heynh., additional genes may be identified from ryegrasses through comparative genomics approaches in the near future.

Diurnal Temperature Variations Significantly Affect Cucumber Fruit Growth

Decreasing the temperature in heated greenhouses significantly reduces heat costs and CO2 emissions. However, the thermophile cucumber is known to be very sensitive to low temperatures. In particular, fruit growth decreases considerably as temperature declines. Nevertheless, reports show that cucumber can be grown successfully at low night temperatures. To explain this phenomenon, it is necessary to investigate the effect of the diurnal temperature variation on fruit growth. Fruit-bearing cucumber plants were grown in two experiments, either at a constant low temperature during the light and dark phase of 15 or 16 °C or at an extremely low temperature during the dark phase of 10 or 11 °C with an increase to 24 or 25 °C during the middle of the light phase resulting in a daily average of 15 or 16 °C, respectively. Introducing the diurnal temperature variation considerably increased fruit growth compared with cultivation at a constant temperature. The vegetative dry matter, however, was greater at a constant than at variable temperatures. Therefore, the total dry matter appeared to be unaffected by the treatments, meaning that photosynthesis was unaffected. Model calculations indicate that the relationship between temperature and fruit growth is not linear in the low-temperature range. For practical applications, it can be concluded that short daily periods with high temperature can mitigate the negative effect of low night temperature on fruit growth and yield.

Digest

Ending summer time increases depressionPutting the clocks back at the end of summer increases the incidence of depressive episodes by 11%, say Danish investigators (Epidemiology 2016; doi: 10.1097/EDE.0000000000000580).Their analysis of the national Psychiatric Central Research Register from 1995 to 2012 included a total of 185 419 hospital contacts for episodes of unipolar depression. The incidence rate increased by 11% during the period of transition from summer time to winter time, then diminished over the following 10 weeks. There was no corresponding increase in spring when clocks moved forward. The authors suggest the change could be explained by ‘distress associated with the sudden advancement of sunset, marking the coming of a long period of short days’.

Estimation of Planting Dates for Roselle (<i>Hibiscus sabdariffa</i> L.) in the Humid Tropical Environment of Owerri, South-eastern Nigeria.

In order to fill the gap existing between the production and consumption of roselle in the humid tropical areas of Nigeria, this experiment was carried out in Owerri between May and December, 2012 to evaluate the effects of planting dates and accessions on the growth and performance of roselle (Hibiscus sabdariffa). Six planting dates including planting at monthly intervals from May to October and two accessions (Purple calyx and Green calyx) were evaluated. The experiment was laid out as a 2 x 6 factorial in Randomized Complete Block (RCB) with three replications. Results revealed that all roselle crops planted in May through August flowered within the same period (26 – 29th September) which coincided with the period of short days in the northern hemisphere. Consequently, roselle planted in May produced flower buds significantly (138 days after planting) compared to other dates. July sown roselle in addition to producing flower bud relatively earlier (80.2 days after planting), had comparably higher number of flower buds/plant and calyx length. Roselle sown in September and October however did not flower. For use as vegetables in soup making, green calyx roselle should be sown in May and harvested not later than 8 weeks after planting. Planting in July appears to favour early flowering and is appropriate for purple calyx roselle.Keywords: Roselle, Accession, Planting Date, Month, Calyx Length

Seasonal Reproductive Activity of Domestic Queens (Felis catus) in the Tropics of Mexico

The objective of this study was to determine the seasonal ovarian activity of domestic queens under the tropical conditions of southern Mexico (19° 30' and 21° 35' N latitude). A total of 250 reproductive tracts were evaluated, and the frequencies of queens with ovarian activity (oestrus, dioestrus or pregnant), anoestrus, pregnancies and ovulation rate by season of the year (spring, summer, autumn and winter) were calculated. Ovarian activity was observed throughout the year, but a significant reduction occurred during the winter; conversely, anoestrous cases were lower during spring and showed an increase during summer, autumn and winter. Pregnancies were most common during spring and decreased during summer, autumn and winter. Ovulation rate varied from 2.5 to 2.8 during the four seasons. Cystic endometrial hyperplasia, pyometra and ovarian follicular cysts were the most common lesions found. The results demonstrate that domestic queens are not seasonal in tropical conditions, but a clear effect of the season of the year reducing ovarian activity is present.

Effect of Refractoriness to Long Photoperiod on Sperm Production and Quality in Tomcats

The aim of this study was to assess whether refractoriness to long photoperiod (LP) could be reversed by subjecting tomcats to a period of short days. Our hypothesis was that photoperiod changes can avoid refractoriness and restore sperm quality and production to that before refractoriness. Tomcats (n = 6) were housed in a conditioned room with LP (12L: 12D) for 45 days of acclimation and then maintained under LP for 18 month. Then, tomcats were changed to a period of decreasing light at a rate of 8 min/day for 1 month. Tomcats stayed for 1 month with short photoperiod (SP; 8L: 16D) and then were switched back to a period of increasing light at a rate of 8 min/day for 1 month. The experiment was completed after tomcats remained in LP for 2 months. Toms were anaesthetized and semen samples were collected by electroejaculation every 2 weeks. Sperm parameters were evaluated in all ejaculates, and data were analysed by anova. Motility, velocity, volume, sperm concentration, total sperm count, viability, acrosome integrity, plasma membrane integrity and sperm morphology were higher during LP compared with a refractory LP (p < 0.01). Likewise, velocity, viability, acrosome integrity, plasma membrane integrity and sperm morphology were higher in a LP compared with a SP (p < 0.05). On the other hand, motility, volume, concentration and total sperm count were similar between LP and SP (p > 0.20).Whereas motility, velocity, viability, acrosome integrity and plasma membrane integrity were similar in a refractory LP compared with SP (p > 0.05), volume, sperm concentration, total sperm count and sperm morphology were lower in a refractory LP compared with SP (p < 0.05). In conclusion, refractoriness and reduced sperm production and quality induced by a prolonged LP of 18 month can be restored after placing tomcats to a SP.