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To survive adverse environments, many animals enter a dormant state such as hibernation, dauer, or diapause. Various Drosophila species undergo adult reproductive diapause in response to cool temperatures and/or short day-length. While flies are less active during diapause, it is unclear how adverse environmental conditions affect circadian rhythms and sleep. Here we show that in diapause-inducing cool temperatures, Drosophila melanogaster exhibit altered circadian activity profiles, including severely reduced morning activity and an advanced evening activity peak. Consequently, the flies have a single activity peak at a time similar to when nondiapausing flies take a siesta. Temperatures ≤15 °C, rather than photoperiod, primarily drive this behavior. At cool temperatures, flies rapidly enter a deep-sleep state that lacks the sleep cycles of flies at higher temperatures and require high levels of stimulation for arousal. Furthermore, we show that at 25 °C, flies prefer to siesta in the shade, a preference that is virtually eliminated at 10 °C. Resting in the shade is driven by an aversion to blue light that is sensed by Rhodopsin 7 outside of the eyes. Flies at 10 °C show neuronal markers of elevated sleep pressure, including increased expression of Bruchpilot and elevated Ca2+ in the R5 ellipsoid body neurons. Therefore, sleep pressure might overcome blue light aversion. Thus, at the same temperatures that cause reproductive arrest, preserve germline stem cells, and extend lifespan, D. melanogaster are prone to deep sleep and exhibit dramatically altered, yet rhythmic, daily activity patterns.

Organisms adapt to unfavorable seasonal conditions to survive. These seasonal adaptations rely on the correct interpretation of environmental cues such as photoperiod, and temperature. Genetic studies in several organisms, including the genetic powerhouse Drosophila melanogaster, indicate that circadian clock components, such as period and timeless, are involved in photoperiodic-dependent seasonal adaptations, but our understanding of this process is far from complete. In particular, the role of temperature as a key factor to complement photoperiodic response is not well understood. The development of new sequencing technologies has proven extremely useful in understanding the plastic changes that the clock and other cellular components undergo in different environmental conditions, including changes in gene expression and alternative splicing. This article discusses the integration of photoperiod and temperature for seasonal biology as well as downstream molecular and cellular pathways involved in the regulation of physiological adaptations that occur with changing seasons. We focus our discussion on the current understanding of the involvement of the molecular clock and the circadian clock neuronal circuits in these adaptations in D. melanogaster.

P/TGMS (Photo/thermo-sensitive genic male sterile) lines are crucial resources for two-line hybrid rice breeding. Previous studies revealed that slow development is a general mechanism for sterility-fertility conversion of P/TGMS in Arabidopsis. However, the difference in P/TGMS genes between rice and Arabidopsis suggests the presence of a distinct P/TGMS mechanism in rice. In this study, we isolated a novel P/TGMS line, ostms19, which shows sterility under high-temperature conditions and fertility under low-temperature conditions. OsTMS19 encodes a novel pentatricopeptide repeat (PPR) protein essential for pollen formation, in which a point mutation GTA(Val) to GCA(Ala) leads to ostms19 P/TGMS phenotype. It is highly expressed in the tapetum and localized to mitochondria. Under high temperature or long-day photoperiod conditions, excessive ROS accumulation in ostms19 anthers during pollen mitosis disrupts gene expression and intine formation, causing male sterility. Conversely, under low temperature or short-day photoperiod conditions, ROS can be effectively scavenged in anthers, resulting in fertility restoration. This indicates that ROS homeostasis is critical for fertility conversion. This relationship between ROS homeostasis and fertility conversion has also been observed in other tested rice P/TGMS lines. Therefore, we propose that ROS homeostasis is a general mechanism for the sterility-fertility conversion of rice P/TGMS lines.

Many migratory animals use daylength, or photoperiod, to signal when to migrate and transition between annual phenological states. Whether animals use photoperiod as a temporal or spatial cue while migrating, however, requires additional empirical support. We used hatch-year dunnocks, Prunella modularis (a songbird), caught during their first migration in southern Sweden to elucidate whether migratory animals incorporate photoperiod as a spatiotemporal cue into their endogenous migratory program during migration. We exposed the migratory-naïve to light environments that simulated either the local photic conditions or a shorter daylength and larger transitions between photoperiods. All birds experienced local geomagnetic conditions. We hypothesized that migratory dunnocks used photoperiod to inform their first migration and predicted that the experimental treatment represented either a spatial displacement to the north or a temporal advancement towards winter at the capture site compared to the local control conditions. We found, though, that the short photoperiods terminated the expression of the migratory phenotype compared to controls by reducing body mass gain and ending migratory activity, indicating that the endogenous migratory program integrates photoperiod during migration. The incorporation of photoperiod into the endogenous program may complement geomagnetic cues to ensure ending migration at the correct time and location. The incorporation of photoperiod can also provide a mechanism that facilitates poleward shifts of overwintering distribution under climate change by allowing migrants to overwinter in newly suitable habitat at higher latitude (i.e. short stopping). • Short photoperiods end migratory activity and reduce migratory gain in body mass. • The endogenous migratory program incorporates photoperiod as a spatiotemporal cue. • Photic and geomagnetic cues may complement each other during migration. • Response to short photoperiods may facilitate short-stopping migration. [ABSTRACT FROM AUTHOR]

Floral initiation in biennial-fruiting red raspberry is controlled by the interaction of temperature and photoperiod. To determine the threshold temperatures for short day (SD) floral initiation in early- and late-flowering cultivars, we exposed plants of 'Glen Ample', 'Glen Mor' and 'Duo' to 12°, 16° and 20°C in a daylight phytotron under naturally decreasing autumn daylength at Ås, Norway (59°40'N). While none of the cultivars ceased growing or initiated floral primordia at 20°C, 'Glen Ample' and 'Glen Mor' initiated buds at 12° and 16°C, whereas 'Duo' formed flower buds at 12°C only. Surprisingly, however, all plants flowered abundantly in spring after winter chilling in the dark at −1.5 ± 0.5°C for 7 months. We discuss two possible explanations for this unusual and novel flowering response. Fractional induction is well known in raspberry, and we visualise that in SD at 20°C, the SD requirement is fulfilled, while floral induction is still blocked by inappropriate temperature. A vernalisation-like response is alternatively suggested as this can take place at near-freezing temperatures in the dark. A combination of the two mechanisms is also possible and likely. We conclude, however, that the two floral induction processes are fundamentally different and controlled by different physiological mechanisms. [ABSTRACT FROM AUTHOR]

Summary The present study investigated the phenolic profile, sugar composition and amino acid profile of lyophilised 10‐day‐old wheatgrass cultivated under varying temperature and photoperiod conditions. The targeted phenolic profile showed the abundant presence of chlorogenic, caffeic, ferulic and p‐coumaric acid. The phenolic content varied with temperature and photoperiod conditions. The comprehensive sugar profile indicated the variation in the concentration of glucose with different growing conditions altered carbohydrate metabolism in wheatgrass. Similarly, the concentration of amino acids also varied with growing conditions. Notably, the concentration of proline, arginine and GABA in wheatgrass from all wheat varieties increased more prominently in photoperiod of 22 h and growth temperature of 22 °C in light and 17 °C in dark as a response of defence mechanism. [ABSTRACT FROM AUTHOR]

Introduction: Maturation in seawater-adapted (smoltified) male Atlantic salmon is undesirable yet frequently reported in fish weighing up to 1 kg reared under intensive conditions in land-based facilities. Although the photoperiod regulates both smoltification and maturation, the optimal post-smoltification regimen for the prevention of maturation is unclear. Methods: In this study, mixed-sex Atlantic salmon weighing 95 g were exposed to three different photoperiod regimes: continuous daylength, gradually decreasing daylength, and short-to-long daylength after the induction of smoltification by the "winter signal" (12 h:12 h light:dark). Fish were maintained under these conditions in triplicate for 18 weeks in a brackish water flow-through system at 12℃ and with a salinity of 20 ppt. This initial phase was followed by a grow-out period (1 kg-2.5 kg) in seawater (32-ppt salinity) at 13℃ for 11 weeks, with exposure to decreasing daylength. Throughout the 29-week study, body condition, gonad development, and morphological traits were assessed. Additionally, during exposure to brackish water, serum 11-ketotestosterone (11-KT) levels were quantified, and the testes were examined histologically. Upon termination of the study, the maturation rate was determined. Results: This study exclusively detected maturation among male salmon. Under continuous light exposure, the number of fish initiating maturity steadily increased from week 8 and continued to increase in the subsequent samplings. In the short-to-long daylength group, a subset of male fish showed elevated 11-KT levels at week 14, although their gonadal development and morphological changes were not evident until week 18. Male fish exposed to decreasing daylength showed no substantial increase in 11-KT levels, although a few fish exhibited advanced gonad development by week 18. At the end of the trial, markedly lower percentages of maturing and fully mature male fish were observed among those fish previously exposed to decreasing daylength. The maturation rates at study termination were 44.4% for the short-to-long daylength group, 29.4% for the continuous daylength group, and 4.3% for the decreasing daylength group. Discussion: These results show that photoperiod can be utilized to regulate maturation in male Atlantic salmon. In addition, decreasing the photoperiod after smoltification seems to limit early sexual maturation without compromising body size development. Thus, decreasing the photoperiod could be utilized to limit maturation in the production of post-smolt salmon or salmon in landbased facilities. [ABSTRACT FROM AUTHOR]

Plants are sessile organisms that have acquired highly plastic developmental strategies to adapt to the environment. Among these processes, the floral transition is essential to ensure reproductive success and is finely regulated by several internal and external genetic networks. The photoperiodic pathway, which controls plant response to day length, is one of the most important pathways controlling flowering. In Arabidopsis photoperiodic flowering, CONSTANS (CO) is the central gene activating the expression of the florigen FLOWERING LOCUS T (FT) in the leaves at the end of a long day. The circadian clock strongly regulates CO expression. However, to date, no evidence has been reported regarding a feedback loop from the photoperiod pathway back to the circadian clock. Using transcriptional networks, we have identified relevant network motifs regulating the interplay between the circadian clock and the photoperiod pathway. Gene expression, chromatin immunoprecipitation experiments, and phenotypic analysis allowed us to elucidate the role of CO over the circadian clock. Plants with altered CO expression showed a different internal clock period, measured by daily leaf rhythmic movements. We showed that CO upregulates the expression of key genes related to the circadian clock, such as CCA1 , LHY , PRR5 , and GI , at the end of a long day by binding to specific sites on their promoters. Moreover, a high number of PRR5-repressed target genes are upregulated by CO, and this could explain the phase transition promoted by CO. The CO-PRR5 complex interacts with the bZIP transcription factor HY5 and helps to localize the complex in the promoters of clock genes. Taken together, our results indicate that there may be a feedback loop in which CO communicates back to the circadian clock, providing seasonal information to the circadian system. Daily information from the clock to plant physiological processes for growth or metabolism needs to integrate information from light quality and daylength. The complex between the regulators of the clock (PRRs), light (HY5), and photoperiod (CONSTANS), guarantees that plant clock controls the photoperiod response but also receives feedback from the changing daylength to make critical physiological and developmental decisions. [ABSTRACT FROM AUTHOR]

Background: Environmental factors influence the mosquito behavior, particularly the oviposition behavior. Therefore, understanding the response of mosquitoes to their environmental conditions like photoperiod, humidity, rainfall, etc., can lead to more precise predictions of transmission cycles which help in the development of more effective vector control strategies. To understand the importance of photoperiod in determining the oviposition cycle of Anopheles subpictus and Culex quinquefasciatus, experiments were conducted under different conditions of normal light (LD 12: 12), reversed photoperiod (DL 12: 12) and continuous light (24 LL) for three consecutive days. Results: It was noticed that ovipositional activity was exclusively restricted to the scotophase. When both the mosquito species were exposed to reverse photoperiod, the oviposition activity also reversed but they showed an erratic oviposition behavior when exposed to 24 h light condition. Conclusions: Understanding the oviposition behavior of mosquito species may favor to design and develop new vector control strategies. [ABSTRACT FROM AUTHOR]

Cats claw creeper leaf-tying moth Hypocosmia pyrochroma (Lepidoptera: Pyralidae) enter pupal diapause in the soil from middle of autumn (April), in response to declining photoperiod. Proportion of larvae entering pupal diapause increased with decreasing Daily Solar Radiation (DSR), and all larvae completing development in winter under low DSR entered pupal diapause. Under natural photoperiod, adults emerged from pupal diapause, from late spring (October) to middle of summer (January), with peak adult emergence in late spring (November) and early summer (December). Pupae did not undergo diapause when the entire development (eggs and all larval instars) occurred under prolonged photoperiod (14 L:10D). However, it was not possible to terminate the pupal diapause either by prolonging photoperiod or by increasing the temperate regimes. Based on larval incidence in the field it is proposed that H. pyrochroma is a bivoltine species with overlapping generations. [ABSTRACT FROM AUTHOR]

The saccus vasculosus is an organ present in gnathostome fishes, located ventral to the hypothalamus and posterior to the pituitary gland, whose structure is highly variable among species. In some fishes, this organ is well-developed; however, its physiological function is still under debate. Recently, it has been proposed that this organ is a seasonal regulator of reproduction. In the present work, we examined the histology, ultrastructure, and development of the saccus vasculosus in Cichlasoma dimerus. In addition, immunohistochemical studies of proteins related to reproductive function were performed. Finally, the potential response of this organ to different photoperiods was explored. C. dimerus presented a well-developed saccus vasculosus consisting of a highly folded epithelium, composed of coronet and supporting cells, closely associated with blood vessels, and a highly branched lumen connected to the third ventricle. Coronet cells showed all the major characteristics described in other fish species. In addition, some of the vesicles of the globules were positive for thyrotropin beta subunit, while luteinizing hormone beta subunit immunostaining was observed at the edge of the apical processes of some coronet cells. Furthermore, neuropeptide Y and gonadotropin inhibitory hormone innervation in the saccus vasculosus of C. dimerus were shown. Finally, animals exposed to the long photoperiod showed lower levels of thyrotropin beta and common alpha subunits expression in the saccus compared to those of animals exposed to short photoperiod. All these results support the hypothesis that the saccus vasculosus is involved in the regulation of reproductive function in fish. [ABSTRACT FROM AUTHOR]

Tetraselmis has been investigated as a potential source of lipids. This microalga possesses good growth characteristics and can be used to develop viable platforms for fatty acid production. This research aims to evaluate the effect of high photon flux density with light-dark cycles and light wavelength on biomass production and fatty acid profile in Tetraselmis subcordiformis. A low light control and treatments with high photon flux density with different light-dark cycles (24:0 h, 12:12 h, 1:1 h, and 15:15 min) and different light wavelength (white, green, red, and blue) were evaluated to determine cell concentration, nutrient consumption, chlorophyll content, photosynthetic yields, lipid content, and fatty acid profile. Significant differences were found in all variables, except for phosphate consumption. High photon flux density promotes cell growth with T. subcordiformis reaching biomass productivities of 0.10 g L-1 day-1 when continuous white light is used. However, no differences were observed in biomass productivities and lipid content for all high photon flux density treatments. On the other hand, red light resulted in higher cell growth, with a productivity of 0.12 g L-1 day-1, and the highest lipid content was achieved under white light. There was a significant effect on the fatty acid profile under different light conditions, with palmitic acid, oleic acid, and eicosapentaenoic acid being the most abundant. This study demonstrated that cellular growth and fatty acid profiles in T. subcordiformis can be influenced by different lighting schemes in the cultivation. [ABSTRACT FROM AUTHOR]

Flowering time and maturity are crucial agronomic traits that affect the regional adaptability of soybean plants. The development of soybean cultivars with early maturity adapted to longer days and colder climates of high latitudes is very important for ensuring normal ripening before frost begins. FUL belongs to the MADS‐box transcription factor family and has several duplicated members in soybeans. In this study, we observed that overexpression of GmFULc in the Dongnong 50 cultivar promoted soybean maturity, while GmFULc knockout mutants exhibited late maturity. Chromatin immunoprecipitation sequencing (ChIP‐seq) and RNA sequencing (RNA‐seq) revealed that GmFULc could bind to the CArG, bHLH and homeobox motifs. Further investigation revealed that GmFULc could directly bind to the CArG motif in the promoters of the GmZTL3 and GmZTL4 genes. Overexpression of GmZTL4 promoted soybean maturity, whereas the ztl4 mutants exhibited delayed maturity. Moreover, we found that the cis element box 4 motif of the GmZTL4 promoter, a motif of light response elements, played an important role in controlling the growth period. Deletion of this motif shortened the growth period by increasing the expression levels of GmZTL4. Functional investigations revealed that short‐day treatment promoted the binding of GmFULc to the promoter of GmZTL4 and inhibited the expression of E1 and E1Lb, ultimately resulting in the promotion of flowering and early maturation. Taken together, these findings suggest a novel photoperiod regulatory pathway in which GmFULc directly activates GmZTL4 to promote earlier maturity in soybean. [ABSTRACT FROM AUTHOR]

CONSTANS-LIKE (COL) genes are a key signalling molecule that regulates plant growth and development during the photoperiod. Our preliminary experiments showed that the photoperiod greatly influence the formation of Tetrastigma hemsleyanum root tubers. In this study, we examined the oscillation patterns and expression characteristics of COL genes in leaves of T. hemsleyanum under different photoperiod conditions. Six genes were selected as candidate reference genes for further analyses: (1) 18S ribosomal RNA (18S rRNA); (2) α-tubulin (TUBA); (3) 30S ribosomal RNA (30S rRNA); (4) TATA binding protein (TBP); (5) elongation factor 1α (EF-1α); and (6) RNA polymerase II (RPII). The geNorm, NormFinder, and BestKeeper software programs were used to evaluate expression stability. Two ThCOL genes were screened in the T. hemsleyanum transcriptome library, and their expression patterns under different photoperiod conditions were analysed using quantitative reverse transcription PCR. The genes EF-1α , TUBA , and 18S rRNA were used to analyse the expression profiles of CONSTANS genes (ThCOL4 and ThCOL5) under different photoperiods. The expression peaks of ThCOL4 and ThCOL5 appeared at different times, demonstrating that their oscillation patterns were influenced by the photoperiod. We speculate that these two ThCOL genes may be involved in different biological processes. The CONSTANS-LIKE (COL) gene is key to plant photoperiod signalling. Tetrastigma hemsleyanum is a medicinal plant that grows only in China. Its root tuber extracts have good effect on the clinical treatment of tumours. The formation and development of its tuberous roots are related to photoperiod. In this study, the expression profiles of COL genes in T. hemsleyanum leaf under different photoperiod conditions was analysed and used to analyse whether COL genes have a role in T. hemsleyanum perception of photoperiod signalling. [ABSTRACT FROM AUTHOR]

The Institute of Physiology of the Czech Academy of Sciences (CAS) has been involved in the field of chronobiology, i.e., in research on temporal regulation of physiological processes, since 1970. The review describes the first 35 years of the research mostly on the effect of light and daylength, i.e., photoperiod, on entrainment or resetting of the pineal rhythm in melatonin production and of intrinsic rhythms in the central biological clock. This clock controls pineal and other circadian rhythms and is located in the suprachiasmatic nuclei (SCN) of the hypothalamus. During the early chronobiological research, many original findings have been reported, e.g. on mechanisms of resetting of the pineal rhythm in melatonin production by short light pulses or by long exposures of animals to light at night, on modulation of the nocturnal melatonin production by the photoperiod or on the presence of high affinity melatonin binding sites in the SCN. The first evidence was given that the photoperiod modulates functional properties of the SCN and hence the SCN not only controls the daily programme of the organism but it may serve also as a calendar measuring the time of a year. During all the years, the chronobiological community has started to talk about “the Czech school of chronobiology”. At present, the today´s Laboratory of Biological Rhythms of the Institute of Physiology CAS continues in the chronobiological research and the studies have been extended to the entire circadian timekeeping system in mammals with focus on its ontogenesis, entrainment mechanisms and circadian regulation of physiological functions. [ABSTRACT FROM AUTHOR]

Background: The transition from vegetative to reproductive growth is a key factor in yield maximization. Sesame (Sesamum indicum), an indeterminate short-day oilseed crop, is rapidly being introduced into new cultivation areas. Thus, decoding its flowering mechanism is necessary to facilitate adaptation to environmental conditions. In the current study, we uncover the effect of day-length on flowering and yield components using F 2 populations segregating for previously identified quantitative trait loci (Si_DTF QTL) confirming these traits. Results: Generally, day-length affected all phenotypic traits, with short-day preceding days to flowering and reducing yield components. Interestingly, the average days to flowering required for yield maximization was 50 to 55 days, regardless of day-length. In addition, we found that Si_DTF QTL is more associated with seed-yield and yield components than with days to flowering. A bulk-segregation analysis was applied to identify additional QTL differing in allele frequencies between early and late flowering under both day-length conditions. Candidate genes mining within the identified major QTL intervals revealed two flowering-related genes with different expression levels between the parental lines, indicating their contribution to sesame flowering regulation. Conclusions: Our findings demonstrate the essential role of flowering date on yield components and will serve as a basis for future sesame breeding. [ABSTRACT FROM AUTHOR]

Summary The interplay of daily life factors, including mood, physical activity, or light exposure, influences sleep architecture and quality. Laboratory‐based studies often isolate these determinants to establish causality, thereby sacrificing ecological validity. Furthermore, little is known about time‐of‐year changes in sleep and circadian‐related variables at high resolution, including the magnitude of individual change across time of year under real‐world conditions. The Ecology of Human Sleep (EcoSleep) cohort study will investigate the combined impact of sleep determinants on individuals’ daily sleep episodes to elucidate which waking events modify sleep patterns. A second goal is to describe high‐resolution individual sleep and circadian‐related changes across the year to understand intra‐ and inter‐individual variability. This study is a prospective cohort study with a measurement‐burst design. Healthy adults aged 18–35 years (N = 12) will be enrolled for 12 months. Participants will continuously wear actimeters and pendant‐attached light loggers. A subgroup will also measure interstitial fluid glucose levels (six paticipants). Every 4 weeks, all participants will undergo three consecutive measurement days of four ecological momentary assessments each day (‘bursts’) to sample sleep determinants during wake. Participants will also continuously wear temperature loggers (iButtons) during the bursts. Body weight will be captured before and after the bursts in the laboratory. The bursts will be separated by two at‐home electroencephalogram recordings each night. Circadian phase and amplitude will be estimated during the bursts from hair follicles, and habitual melatonin onset will be derived through saliva sampling. Environmental parameters (bedroom temperature, humidity, and air pressure) will be recorded continuously. [ABSTRACT FROM AUTHOR]

Background: Improving the rate of genetic gain of cereal crop will rely on the accelerated crop breeding pipelines to allow rapid delivery of improved crop varieties. The laborious, time-consuming traditional breeding cycle, and the seasonal variations are the key factor restricting the breeder to develop new varieties. To address these issues, a revolutionized cost-effective speed breeding protocol for large-scale rice germplasm advancement is presented in the present study. The protocol emphasises on optimizing potting material, balancing the double-edged sword of limited nutritional dose, mode and stage of application, plant density, temperature, humidity, light spectrum, intensity, photoperiod, and hormonal regulation to accelerate rice growth and development. Results: The plant density of 700 plants/m2, cost-effective halogen tubes (B:G:R:FR-7.0:27.6:65.4:89.2) with an intensity of ∼ 750–800 µmol/m2/s and photoperiod of 13 h light and 11 h dark during seedling and vegetative stage and 8 h light and 16 h dark during reproductive stage had a significant effect (P < 0.05) on reducing the mean plant height, tillering, and inducing early flowering. Our results confirmed that one generation can be achieved within 68–75 days using the cost-effective SpeedyPaddy protocol resulting in 4–5 generations per year across different duration of rice varieties. The other applications include hybridization, trait-based phenotyping, and mapping of QTL/genes. The estimated cost to run one breeding cycle with plant capacity of 15,680 plants in SpeedyPaddy was $2941 including one-time miscellaneous cost which is much lower than the advanced controlled environment speed breeding facilities. Conclusion: The protocol offers a promising cost-effective solution with average saving of 2.0 to 2.6 months per breeding cycle with an integration of genomics-assisted selection, trait-based phenotyping, mapping of QTL/genes, marker development may accelerate the varietal development and release. This outstanding cost-effective break-through marks a significant leap in rice breeding addressing climate change and food security. [ABSTRACT FROM AUTHOR]

This study investigated the influence of photoperiod (day length) on the efficacy of grape seed proanthocyanidin extract (GSPE) in mitigating metabolic disorders in obese rats fed a cafeteria diet. Rats were exposed to standard (L12), long (L18), or short (L6) photoperiods and treated with GSPE or vehicle. In the standard photoperiod, GSPE reduced body weight gain (50.5%), total cholesterol (37%), and triglycerides (34.8%), while increasing the expression of hepatic metabolic genes. In the long photoperiod, GSPE tended to decrease body weight gain, increased testosterone levels (68.3%), decreased liver weight (12.4%), and decreased reverse serum amino acids. In the short photoperiod, GSPE reduced glycemia (~10%) and lowered triglyceride levels (38.5%), with effects modified by diet. The standard photoperiod showed the greatest efficacy against metabolic syndrome-associated diseases. The study showed how day length affects GSPE's benefits and underscores considering biological rhythms in metabolic disease therapies. [ABSTRACT FROM AUTHOR]

Plants must accurately integrate external environmental signals with their own development to initiate flowering at the appropriate time for reproductive success. Photoperiod and temperature are key external signals that determine flowering time; both are cyclical and periodic, and they are closely related. In this review, we describe photoperiod-sensitive genes that simultaneously respond to temperature signals in rice (Oryza sativa). We introduce the mechanisms by which photoperiod and temperature synergistically regulate heading date and regional adaptation in rice. We also discuss the prospects for designing different combinations of heading date genes and other cold tolerance or thermo-tolerance genes to help rice better adapt to changes in light and temperature via molecular breeding to enhance yield in the future. [ABSTRACT FROM AUTHOR]

Adaptation of physiology and behavior to seasonal changes in the environment are for many organisms essential for survival. Most of our knowledge about the underlying mechanisms comes from research on photoperiodic regulation of reproduction in plants, insects and mammals. However, even humans, who mostly live in environments with minimal seasonal influences, show annual rhythms in physiology (e.g., immune activity, brain function), behavior (e.g., sleep–wake cycles) and disease prevalence (e.g., infectious diseases). As seasonal variations in environmental conditions may be drastically altered due to climate change, the understanding of the mechanisms underlying seasonal adaptation of physiology and behavior becomes even more relevant. While many species have developed specific solutions for dedicated tasks of photoperiodic regulation, we find a number of common principles and mechanisms when comparing insect and mammalian systems: (1) the circadian system contributes to photoperiodic regulation; (2) similar signaling molecules (VIP and PDF) are used for transferring information from the circadian system to the neuroendocrine system controlling the photoperiodic response; (3) the hormone melatonin participates in seasonal adaptation in insects as well as mammals; and (4) changes in photoperiod affect neurotransmitter function in both animal groups. The few examples of overlap elaborated in this perspective article, as well as the discussion on relevance for humans, should be seen as encouragement to unravel the machinery of seasonal adaptation in a multitude of organisms. [ABSTRACT FROM AUTHOR]

Decades have now passed since Colin Pittendrigh first proposed a model of a circadian clock composed of two coupled oscillators, individually responsive to the rising and setting sun, as a flexible solution to the challenge of behavioral and physiological adaptation to the changing seasons. The elegance and predictive power of this postulation has stimulated laboratories around the world in searches to identify and localize such hypothesized evening and morning oscillators, or sets of oscillators, in insects, rodents, and humans, with experimental designs and approaches keeping pace over the years with technological advances in biology and neuroscience. Here, we recount the conceptual origin and highlight the subsequent evolution of this dual oscillator model for the circadian clock in the mammalian suprachiasmatic nucleus; and how, despite our increasingly sophisticated view of this multicellular pacemaker, Pittendrigh's binary conception has remained influential in our clock models and metaphors. [ABSTRACT FROM AUTHOR]

The fruit fly Drosophila melanogaster exhibits two activity peaks, one in the morning and another in the evening. Because the two peaks change phase depending on the photoperiod they are exposed to, they are convenient for studying responses of the circadian clock to seasonal changes. To explain the phase determination of the two peaks, Drosophila researchers have employed the two-oscillator model, in which two oscillators control the two peaks. The two oscillators reside in different subsets of neurons in the brain, which express clock genes, the so-called clock neurons. However, the mechanism underlying the activity of the two peaks is complex and requires a new model for mechanistic exploration. Here, we hypothesize a four-oscillator model that controls the bimodal rhythms. The four oscillators that reside in different clock neurons regulate activity in the morning and evening and sleep during the midday and at night. In this way, bimodal rhythms are formed by interactions among the four oscillators (two activity and two sleep oscillators), which may judiciously explain the flexible waveform of activity rhythms under different photoperiod conditions. Although still hypothetical, this model would provide a new perspective on the seasonal adaptation of the two activity peaks. [ABSTRACT FROM AUTHOR]

The effect of photoperiod on the growth performance, survival rate, swim bladder inflation (SBI) and presence of vertebral anomalies was evaluated in pikeperch larvae reared under intensive production in a recirculating system (RAS). Three different photoperiods were tested from 1 to 30 days post hatch, 12:12 LD, 16:8 LD and 24:0 LD. Larvae were stocked with an initial density of 100 larvae per liter, light intensity of 100 lx and 16.0°C water temperature. The SGR among treatments ranged between 11.17 and 12.04% day−1. The highest survival rate (56.7 ± 2.4%) was found in 24:0 LD with a negative effect on the number of larvae with SBI. The highest presence of vertebral anomalies at 30 dph was found in 24:0 LD (40.8 ± 8.2%) compared to 12:12 LD (2.5 ± 1.4%) and 16:8 LD (1.7 ± 1.6%). These results suggest that constant light compromises culture of pikeperch larvae in RAS. A 16:8 LD photoperiod seems suitable for the growth performance, SBI and low vertebral anomalies at this life stage. [ABSTRACT FROM AUTHOR]

An understanding of thermal limits and variation across geographic regions is central to predicting how any population may respond to global change. Latitudinal clines, in particular, have been used to demonstrate that populations can be locally adapted to their own thermal environment and, as a result, not all populations will be equally impacted by an increase in temperature. But how robust are these signals of thermal adaptation to the other ecological challenges that animals commonly face in the wild? Seasonal changes in population density, food availability, or photoperiod are common ecological challenges that could disrupt patterns of thermal tolerance along a cline if each population differentially used these signals to anticipate future temperatures and adjust their thermal tolerances accordingly. In this study, we aimed to test the robustness of a cline in thermal tolerance to simulated signals of seasonal heterogeneity. Experimental animals were derived from clones of the Australian water flea, Daphnia carinata, sampled from nine distinct populations along a latitudinal transect in Eastern Australia. We then factorially combined summer (18 h light, 6 h dark) and winter (6 h light, 18 h dark) photoperiods with high (5 million algal cells individual−1 day−1) and low (1 million algal cells individual−1 day−1) food availabilities, before performing static heat shock assays to measure thermal tolerance. We found that the thermal tolerances of the clonal populations were sensitive to both measures of seasonal change. In general, higher food availability led to an increase in thermal tolerances, with the magnitude of the increase varying by clone. In contrast, a switch in photoperiod led to rank‐order changes in thermal tolerances, with heat resistance increasing for some clones, and decreasing for others. Heat resistance, however, still declined with increasing latitude, irrespective of the manipulation of seasonal signals, with clones from northern populations always showing greater thermal resistance, most likely driven by adaptation to winter thermal conditions. While photoperiod and food availability can clearly shape thermal tolerances for specific populations, they are unlikely to overwhelm overarching signals of thermal adaptation, and thus, observed clines in heat resistance will likely have remained robust to these forms of seasonal heterogeneity. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) is a common staple food widely cultivated and consumed globally. The increase in world population and slow genetic gain in rice production in the face of a rapidly evolving climate could cause food scarcity and decreased crop productivity. It is crucial to expedite the development and release of climate-resilient crop varieties through selective breeding and improvement to mitigate the impact of climate change. Speed breeding has emerged as a promising tool for rice breeding, offering the potential to accelerate the generation time. By streamlining the breeding process and reducing the time taken for each generation, speed breeding empowers breeders to screen for desired traits rapidly and efficiently, enhancing the selection and development of improved rice varieties to meet the growing global demand for food. This review focuses on the applications of speed breeding technology to accelerate rice breeding and further highlights the critical factors for speed breeding development in rice production, such as temperature, humidity, light, and genetic diversity. Understanding and optimizing these factors is vital in successfully implementing speed breeding technology in developing robust, high-yielding, and climate-resilient rice varieties for feeding the future. [ABSTRACT FROM AUTHOR]

Light, as a critical environmental factor, plays a pivotal role in photosynthesis, ultimately influencing the timing of bud flush in tea plants. However, the synergistic effects of different photoperiods and light qualities on the timing of bud flush in the albino tea cultivar 'HuangKui' (later germination variety) remain unknown. Thus, the objective of this study was to investigate the effects of different photoperiods (12L/12D, 14L/10D, 16L/8D, and 18L/6D, where L = the number of daylight hours and D = the number of hours of darkness) and ratios of red (R) to blue (B) light (R/B 1:1, R/B 1:2, R/B 1:3, and R/B 2:1) on the germination and growth of the albino tea variety 'HuangKui'. In our study, we examined how different photoperiods and red light and blue light affected tea germination and growth by investigating the timing of bud flush, photosynthesis, chlorophyll content, and growth indicators. First, our study showed that 'HuangKui' germinated 4 days, 2 days, and 1 day earlier under the 16L/8D photoperiod at the one bud and one leaf period compared with plants cultivated under the 12L/12D, 14L/10D, and 18L/6D photoperiods under light simulating the solar spectrum. Also, the growth of 'HuangKui' was maximumly promoted under the 16L/8D photoperiod treatment. Additionally, the earliest germination of 'HuangKui' was observed for the 16L/8D photoperiod under the R/B 2:1 (red/blue) treatment compared with the other treatments. Moreover, the greatest plant height, length of the new shoots, and new leaf areas were detected in the albino tea variety 'HuangKui' under R/B 2:1. Moreover, the contents of auxin (indole acetic acid, IAA) and trans-zeatin (tZ) under R/B 2:1 were significantly higher than those under the R/B 1:1 and control treatments with the 16L/8D photoperiod. Additionally, the auxin-related expression levels of CsIAA13, CsGH3.1, CsAUX1, and CsARF2 under the R/B 2:1 treatment were significantly higher than those in the control. The expression of CsARR-B, a positive regulator of cytokinin-related genes, was significantly higher under the R/B 2:1 treatment than under the control treatment, while the opposite result was found for the expression of the negative regulator CsARR-A. Therefore, the R/B 2:1 treatment with the 16L/8D photoperiod was an appropriate means of timing the bud flush for the albino tea variety 'HuangKui', which may be related to IAA or tZ signal transduction. In conclusion, our research offers a novel lighting strategy that promotes the germination and growth of albino tea cultivars. [ABSTRACT FROM AUTHOR]

To explore the effect of the photoperiod on the accumulation and distribution of dry matter in potato, a pot experiment was carried out in 2021 and 2022 with two varieties (Atlantic and Hezuo 88). The varieties were used as the main plot, and light treatments (short-day and long-day) were used as the subplot. The results showed that extended hours of light delayed tuber formation in Hezuo 88, however, the effect was not obvious for the Atlantic. Comprehensive analyses were carried out using the potato developmental process, dynamic equation fitting of the tuber and whole-plant dry matter accumulation, and the dry matter accumulation and distribution rate of each organ of the two varieties under two photoperiods. The two photoperiods had different effects on the parameters of rapid tuber and whole-plant dry matter accumulation: the starting point of the period of the rapid dry matter accumulation (t1), the duration period of the rapid dry matter accumulation (Δt), and the average growth rate of the period of the rapid dry matter accumulation (Vmean). According to comprehensive analysis, tuber dry matter accumulation in Atlantic was the highest under the short-day condition, while Hezuo 88 showed the lowest tuber dry matter accumulation under the long-day condition and was the latest to enter the rapid tuber dry matter accumulation period. The whole-plant dry matter accumulation in Atlantic was the highest under the long-day condition and lowest in Hezuo 88; meanwhile, Hezuo 88 was the latest to enter the rapid whole-plant dry matter accumulation period. In terms of the dry matter accumulation and dry matter partitioning ratio of various organs, Hezuo 88 had the lowest mean tuber dry matter accumulation and partitioning ratio under the long-day condition but the highest mean stem, leaf, root, underground stem, and stolon dry matter partitioning ratio. On the contrary, Atlantic had the highest mean tuber dry matter accumulation and portioning ratio under the short-day condition but the lowest mean stem, leaf, root, underground stem, and stolon dry matter partitioning ratio. It was concluded that different varieties of potato respond differently to the photoperiod. In the case of Hezuo 88, prolonging the photoperiod affected the dynamics and distribution of dry matter accumulation; increased the stem, leaf, root, and underground stem dry matter partitioning ratio; and decreased the tuber dry matter partitioning ratio, which resulted in a decrease in tuber dry matter accumulation and consequently delayed the emergence of the equilibrium period between the aboveground and underground dry matter. [ABSTRACT FROM AUTHOR]

This study was conducted to assess the effect of photoperiod on the growth and maturation of male gonads in featherback fish, Notopterus notopterus, from Farhatabad Nala of Gulbarga district, Karnataka, India. Five experimental groups were setup with five different photoperiod treatments, such as the control group (10 hr light and 14 hr dark (10L:14D), 18 hr light and 6 hr dark (18L:06D), 24 hr continuous light (24L:00D), 24 hr continuous dark (00L:24D) and 6 hr light and 18 hr dark (6L:18D). The parameters selected for the gonadal response to these light and dark regimes were the gonadosomatic index (GSI) and the hepatosomatic index (HSI). The mean GSI values were highest in the fish after 24 hours of continuous dark treatment (0.28±0.008, p < 0.001), suggesting an enhancement of gonadal growth with increased spermatogenesis. On the other hand, the same parameter was minimal in the fish with a 24-hour continuous light period (0.10 ± 0.008, p<0.001), revealing the inhibition of spermatogenesis with degenerated testicular components. The hepatosomatic index studies indicate that there is an increase in HSI during longer periods of light exposure and a decrease during shorter periods of light exposure. The decrease of HSI in longer periods of darkness exposure may be related to the hepatic involvement in gonadal growth and maturity. This study indicates that prolonged photoperiods negatively affect the reproductive success of N. notopterus. [ABSTRACT FROM AUTHOR]

Objective: To examine light and heat effects on the morphological, histological, and micrometric structure of the prostate of rats. Methods: Thirty adult male rats were divided into three groups. The control group was kept under 20 °C-22 °C and an artificial 12 h/12 h day/night cycle; the temperature group was under normal light and at (42±1) °C heat for 4 to 5 h daily, and the light group was exposed to 8 h/16 h day/night cycle with 20 °C-22 °C. Rats were weighed five times (at the beginning of the study and every seven days). Five milliliters (mL) of their peripheral blood were taken. The tissue staining was performed using the hematoxylin-eosin (H & E) stain and periodic acid-Schiff (PAS). In the following, tissue and cellular reactions to the PAS were examined. Results: Folds were located entirely on the surface of the anterior lobe and periphery of the other lobes. The secretory units in the anterior lobe were more than the lateral lobe. A strong reaction of the secretory cells to the PAS was observed. Testosterone serum levels of the light group also significantly increased compared to the control group (P

Abstract Background Environmental factors influence the mosquito behavior, particularly the oviposition behavior. Therefore, understanding the response of mosquitoes to their environmental conditions like photoperiod, humidity, rainfall, etc., can lead to more precise predictions of transmission cycles which help in the development of more effective vector control strategies. To understand the importance of photoperiod in determining the oviposition cycle of Anopheles subpictus and Culex quinquefasciatus, experiments were conducted under different conditions of normal light (LD 12: 12), reversed photoperiod (DL 12: 12) and continuous light (24 LL) for three consecutive days. Results It was noticed that ovipositional activity was exclusively restricted to the scotophase. When both the mosquito species were exposed to reverse photoperiod, the oviposition activity also reversed but they showed an erratic oviposition behavior when exposed to 24 h light condition. Conclusions Understanding the oviposition behavior of mosquito species may favor to design and develop new vector control strategies.

Abstract Background The transition from vegetative to reproductive growth is a key factor in yield maximization. Sesame (Sesamum indicum), an indeterminate short-day oilseed crop, is rapidly being introduced into new cultivation areas. Thus, decoding its flowering mechanism is necessary to facilitate adaptation to environmental conditions. In the current study, we uncover the effect of day-length on flowering and yield components using F $$_2$$ 2 populations segregating for previously identified quantitative trait loci (Si_DTF QTL) confirming these traits. Results Generally, day-length affected all phenotypic traits, with short-day preceding days to flowering and reducing yield components. Interestingly, the average days to flowering required for yield maximization was 50 to 55 days, regardless of day-length. In addition, we found that Si_DTF QTL is more associated with seed-yield and yield components than with days to flowering. A bulk-segregation analysis was applied to identify additional QTL differing in allele frequencies between early and late flowering under both day-length conditions. Candidate genes mining within the identified major QTL intervals revealed two flowering-related genes with different expression levels between the parental lines, indicating their contribution to sesame flowering regulation. Conclusions Our findings demonstrate the essential role of flowering date on yield components and will serve as a basis for future sesame breeding.

OPN5 is one of the main deep brain photoreceptors (DBPs), converting photoperiodic information into neuroendocrine signals to regulate reproduction in birds. This study investigated the mechanism of OPN5-mediated photoperiodic regulation of reproduction by active immunization against OPN5. 96 female quail were divided into OPN5-immunized and control group under the same photoperiod: 16 L:8 D (d 1 to d 35), 8 L:16 D (d 36 to d 70) and 12 L:12 D (d 71 to d 126). OPN5-immunized group was conducted with OPN5 protein vaccination and control group was given a blank vaccine. Samples were collected on d 1, d 30, d 60, and d 126. Results showed switching photoperiod to 8 L:16 D decreased the laying rate, GSI%, numbers of YFs and WFs, serum levels of PRL, P4 and E2, and pituitary PRL and TSHβ protein expressions in both groups (P < 0.05). Whereas the OPN5-immunized group exhibited higher laying rates than the control group (P < 0.05). The control group showed reduced GnRHR and TSHβ gene expressions in the pituitary and increased GnIH and DIO3 transcript and/or protein abundance in the hypothalamus. (P < 0.05). The OPN5-immunized group had lower DIO3 expression at both mRNA and protein levels. (P < 0.05). Switching photoperiod from 8 L:16 D to 12 L:12 D increased the laying rates, GSI%, numbers of YFs and WFs, serum levels of PRL, and PRL protein expression in both groups (P < 0.05), and the responses were more pronounced in OPN5-immunized group (P < 0.05). In contrast to the control group, quail with OPN5-immunization had higher OPN5 and DIO2 transcript and/or protein levels but lower DIO3 expressions in the hypothalamus along the transition photoperiods (P < 0.05). The results revealed that OPN5 responds to photoperiod transition, and its activation mediates related signaling to up-regulate TSH-DIO2/DIO3 pathway and VIP-PRL secretion to prime quail reproductive functions. • OPN5 immunization slowed down the Inhibition of short-photoperiod on reproduction. • OPN5 immunization enhanced the stimulation of prolong-photoperiod on reproduction. • OPN5 immunization enhanced OPN5 signaling to promote follicular development in quail. • OPN5 may have a regulatory effect on PRL while mediating photoperiod. [ABSTRACT FROM AUTHOR]

Efficient post‐drought recovery of growth and assimilation enables a plant to return to its undisturbed state and functioning. Unlike annual plants, trees suffer not only from the current drought, but also from cumulative impacts of consecutive water stresses which cause adverse legacy effects on survival and performance. This review provides an integrated assessment of ecological, physiological and molecular evidence on the recovery of growth and photosynthesis in trees, with a view to informing the breeding of trees with a better ability to recover from water stress. Suppression of recovery processes can result not only from stress damage but also from a controlled downshift of recovery as part of tree acclimation to water‐limited conditions. In the latter case, recovery processes could potentially be activated by turning off the controlling mechanisms, but several obstacles make this unlikely. Tree phenology, and specifically photoperiodic constraints, can limit post‐drought recovery of growth and photosynthesis, and targeting these constraints may represent a promising way to breed trees with an enhanced ability to recover post‐drought. The mechanisms of photoperiod‐dependent regulation of shoot, secondary and root growth and of assimilation processes are reviewed. Finally, the limitations and trade‐offs of altering the photoperiodic regulation of growth and assimilation processes are discussed. [ABSTRACT FROM AUTHOR]

Farming of red tilapia is one promising direction in aquaculture. The objective of this study was to investigate the impact of long-day photoperiod on the growth performance, reproductive parameters, maturity, sex ratio, β-carotene content, and skin coloration of red tilapia. Early life larvae were allocated into three treatment groups in triplicates: T1 = control group (12L:12D), T2 = long-day group (18L:6D), and T3 = continuous illumination group (24L:0D) for 90 days. By the end of the experiment, gonadosomatic index (GSI), relative fecundity, steroid hormones, maturity stages, sex ratio, and ovarian and testicular histology were examined; also, growth performance, survival rate, skin color, and total β-carotene content were measured. The results indicated that GSI% and serum testosterone (T) in T3 group significantly increased with greater amount of spermatozoa of male fish. Also, growth parameters and HSI% in female fish displayed significantly increased for T3 group. Females in group T2 showed significant elevation in GSI%, relative fecundity, and estradiol (E2) with higher number of mature stage. Continuous light group (T3) showed shifted male sex ratio, while female percentage was higher in T2 group. The total β-carotene content of T3 group showed significant elevation with less number of black spots. This study demonstrated that continuous light manipulation during red tilapia early life could stimulate the growth and enhance coloration by reducing black spots that significantly affects economic profitability. Long-day application was effective in female reproductive performance and maturity. This study also served as an important reference for red tilapia aquaculture. [ABSTRACT FROM AUTHOR]

Properly regulated flowering time is pivotal for successful plant reproduction. The floral transition from vegetative growth to reproductive growth is regulated by a complex gene regulatory network that integrates environmental signals and internal conditions to ensure that flowering takes place under favorable conditions. Brassica rapa is a diploid Cruciferae species that includes several varieties that are cultivated as vegetable or oil crops. Flowering time is one of the most important agricultural traits of B. rapa crops because of its influence on yield and quality. The transition to flowering in B. rapa is regulated by several environmental and developmental cues, which are perceived by several signaling pathways, including the vernalization pathway, the autonomous pathway, the circadian clock, the thermosensory pathway, and gibberellin (GA) signaling. These signals are integrated to control the expression of floral integrators BrFTs and BrSOC1s to regulate flowering. In this review, we summarized current research advances on the molecular mechanisms that govern flowering time regulation in B. rapa and compare this to what is known in Arabidopsis.

This review highlights the recent developments regarding neuroendocrine mechanisms controlling teleost reproduction. In teleosts, the pituitary gland receives major neuronal innervations from Gnrh neurons as well as minor innervations from small population of neurons that will secrete neurotransmitters and/or neuropeptides. The diversity of Kiss/Kissr system in various teleost species and their actions in the context of HPG axis and reproduction has been extensively covered. In teleost model systems, zebrafish and medaka, mutant lines for key components of the HPG axis have been generated through targeted mutagenesis but surprisingly most of the mutants developed normally without major defects in reproduction; these mutant phenotypes are described. In the last decade, complex role of diverse neuropeptides in teleost reproduction is being revealed. A brief overview about the reproductive functions of neuropeptides is presented. Finally, the effects of environmental factors namely photoperiodism and temperature on the functions of HPG axis is summarised.

SUMMARY: Photoperiod employs complicated networks to regulate various developmental processes in plants, including flowering transition. However, the specific mechanisms by which photoperiod affects epigenetic modifications and gene expression variations in plants remain elusive. In this study, we conducted a comprehensive analysis of DNA methylation, small RNA (sRNA) accumulation, and gene expressions under different daylengths in facultative long‐day (LD) grass Brachypodium distachyon and short‐day (SD) grass rice. Our results showed that while overall DNA methylation levels were minimally affected by different photoperiods, CHH methylation levels were repressed under their favorable light conditions, particularly in rice. We identified numerous differentially methylated regions (DMRs) that were influenced by photoperiod in both plant species. Apart from differential sRNA clusters, we observed alterations in the expression of key components of the RNA‐directed DNA methylation pathway, DNA methyltransferases, and demethylases, which may contribute to the identified photoperiod‐influenced CHH DMRs. Furthermore, we identified many differentially expressed genes in response to different daylengths, some of which were associated with the DMRs. Notably, we discovered a photoperiod‐responsive gene MYB11 in the transcriptome of B. distachyon, and further demonstrated its role as a flowering inhibitor by repressing FT1 transcription. Together, our comparative and functional analysis sheds light on the effects of daylength on DNA methylation, sRNA accumulation, and gene expression variations in LD and SD plants, thereby facilitating better designing breeding programs aimed at developing high‐yield crops that can adapt to local growing seasons. Significance Statement: Our comprehensive analysis of DNA methylation, small RNA accumulation, and gene expressions combined with functional analysis of long‐day (LD) photoperiod‐induced MYB11 in Brachypodium distachyon offers insights into the impact of daylength on epigenetic modifications, and gene expression variations in LD and short‐day plants. Our research fosters the potential for more calculated scheming of breeding programs that strive to produce high‐yielding crops capable of adapting to their respective local growing seasons. [ABSTRACT FROM AUTHOR]

We investigated the effect of supplemental CO2, gibberellic acid (GA3), and light on the quality and yield of Humulus lupulus L. strobili (cones). When applied separately, CO2 and light increased the yield by 22% and 43%, respectively, and had a significant effect on the components of cone mass and quality. Exogenous GA3 increased flower set; however, the yield decreased by approximately 33%. Combining CO2, GA3, and light, and any combination thereof, resulted in significant increases in flower set and cone yield enhancement compared to separate applications. A synergistic effect occurred when some factors were combined. For example, the combination of CO2 and light resulted in a yield increase of approximately 122%. The combination of all three resources, CO2, GA3, and light, resulted in an approximate 185% yield increase per plant. Thus, in comparison to the addition of one supplementary resource, a greater increase in yield resulted from the combination of two or more supplemental resources. Flower set stimulation due to GA3 decreased cone alpha- and beta-acid quality attributes, unless combined with CO2 and light as additional carbohydrate-generating resources. Additional research is needed to close the hop yield gap between current hop yields and the achievement of the plant's genetic potential. [ABSTRACT FROM AUTHOR]

Seasonal variation in photoperiod may affect psychosocial and physical well‐being in healthy persons. We tested this hypothesis in healthy pre‐menopausal women, without a history of mood disorders, living year‐round in Reykjavik, Iceland (64.1°N). Participants reported daily self‐assessments of well‐being throughout a complete ovulatory menstrual cycle in summer and/or winter (70% participated in both seasons). Scores for mood, cognitive acuity, social support, physical health and a composite of these four indicators were each significantly higher in summer than in winter (linear mixed effects models: p <.001 for each model); tiredness did not differ by season. The effect of season was not significantly changed by inclusion of body mass index and/or age as covariates. Some prior studies have been hampered by sparse time sampling, inattention to covariates and/or relying on recalled data. This is to our knowledge the first investigation to test the study hypothesis with daily real‐time data spanning complete ovulatory menstrual cycles in each of two seasons. This dense sampling has revealed modest seasonal variation in well‐being in healthy women. Daylength (sunlight exposure) is likely a major, but not necessarily sole, factor in these seasonal differences in well‐being; temperature is likely less important given Iceland's relatively moderate (for its high latitude) seasonal temperature swings. [ABSTRACT FROM AUTHOR]

Sorghum production system in the semi-arid region of Africa is characterized by low yields which are generally attributed to high rainfall variability, poor soil fertility, and biotic factors. Production constraints must be well understood and quantified to design effective sorghum-system improvements. This study uses the state-of-the-art in silico methods and focuses on characterizing the sorghum production regions in Mali for drought occurrence and its effects on sorghum productivity. For this purpose, we adapted the APSIM-sorghum module to reproduce two cultivated photoperiod-sensitive sorghum types across a latitude of major sorghum production regions in Western Africa. We used the simulation outputs to characterize drought stress scenarios. We identified three main drought scenarios: (i) no-stress; (ii) early pre-flowering drought stress; and (iii) drought stress onset around flowering. The frequency of drought stress scenarios experienced by the two sorghum types across rainfall zones and soil types differed. As expected, the early pre-flowering and flowering drought stress occurred more frequently in isohyets < 600 mm, for the photoperiod-sensitive, late-flowering sorghum type. In isohyets above 600 mm, the frequency of drought stress was very low for both cultivars. We quantified the consequences of these drought scenarios on grain and biomass productivity. The yields of the highly-photoperiod-sensitive sorghum type were quite stable across the higher rainfall zones > 600 mm, but was affected by the drought stress in the lower rainfall zones < 600 mm. Comparatively, the less photoperiod-sensitive cultivar had notable yield gain in the driest regions < 600 mm. The results suggest that, at least for the tested crop types, drought stress might not be the major constraint to sorghum production in isohyets > 600 mm. The findings from this study provide the entry point for further quantitative testing of the Genotype × Environment × Management options required to optimize sorghum production in Mali. [ABSTRACT FROM AUTHOR]

New protein resources can be developed to alleviate the shortage of protein in the feed industry. Photosynthetic bacteria (PSB) can serve as unique microbial protein sources. Among them, the light environment is a crucial influencing factor in the growth and metabolism of PSB. In this study, the light supply strategies were employed to enhance the growth of Rhodopseudomonas palustris (R. palustris) and the synthesis of single-cell protein (SCP) in the wastewater resource systems of PSB. Additionally, a systematic analysis was made on the correlations between substance synthesis and pollutant degradation under different light supply strategies. The results indicated that a full spectrum of light was more conducive to the accumulation of biomass and protein concentration in R. palustris, compared with the segmented spectra. Under incandescent lamp and white LED irradiation, the highest biomass concentration, daily bacterial production, bacterial yield, and protein concentration reached (1 023.18±201.17) mg/L, (0.32±0.10) g/(L·d), (0.31±0.03) mg/mg and (555.66±9.18) mg/L, respectively. These values increased by 37.26%-43.79%, 108.82%-137.92%, 42.01%-91.85%, and 24.77%-33.47%, respectively, compared with the blue and green light groups (P<0.05). Moderate light intensity was favored to accumulate biomass and protein concentration, while excessive or low intensity was detrimental to the accumulation of high-value products by R. palustris. Specifically, under a light intensity of 120 μmol/(m² ·s), the highest biomass concentration, daily bacterial production, bacterial yield, and protein concentration reached (1 646.12±2.47) mg/L, (0.77±0.01) g/(L·d), (0.44±0.05) mg/mg and (803.59±2.62) mg/L, respectively. There was an increase of 60.23%-140.19% in biomass and an increase of 61.90%-94.18% in protein concentration, compared with the 0 μmol/(m² ·s) (control) and 240 μmol/(m² ·s) groups (P<0.05). Intermittent light exhibited significant advantages over continuous light. An appropriate light cycle was selected to significantly promote the growth and protein synthesis of R. palustris. In the condition of 18 L/6 D, the highest biomass concentration, daily bacterial production, protein concentration, and nitrogen conversion efficiency reached (1 140.56±19.72) mg/L, (0.32±0.02) g/(L·d), (506.53±48.20) mg/L, and (1.77±0.35) mg/mg, respectively. There were increases by 17.06%-93.21%, 54.43%-299.93%, 24.35%-43.88% and 38.78%, respectively, compared with the 3 L/21 D and 9 L/15 D groups (P<0.05). The 3 L/21 D group exhibited the highest protein content at 67.47%, indicating an increase of 21.96%-44.54%, compared with all the other experimental groups (P<0.05). Additionally, under conditions of incandescent light, the light intensity of 120 μmol/(m² ·s) and photoperiod of 18 L/6 D, COD and NH4+ -N removal efficiencies reached 72.03%-78.40%. Furthermore, there were significant negative correlations between light intensity and spectrum with the protein content and concentration. Conversely, the photoperiod shared a significant positive correlation with protein concentration. Therefore, the photoperiod can be expected to enhance the production of SCP by R. palustris. Its mechanism involves the direct regulation of PSB growth and metabolism by the light/dark cycle. During the light period, PSB pigments capture photons through photoreactions, driving electron transfer, generating electrical energy, and ultimately converting it into ATP; Simultaneously, the Calvin cycle efficiency is enhanced, leading to the accumulation of cell growth and SCP. During the dark period, PSB cells focus on the division process, increasing overall biomass. This research can provide innovative insights to enhance the SCP synthesis in wastewater systems using PSB. [ABSTRACT FROM AUTHOR]

Main conclusion: The hop phenological cycle was described in subtropical condition of Brazil showing that flowering can happen at any time of year and this was related to developmental molecular pathways. Hops are traditionally produced in temperate regions, as it was believed that vernalization was necessary for flowering. Nevertheless, recent studies have revealed the potential for hops to flower in tropical and subtropical climates. In this work, we observed that hops in the subtropical climate of Minas Gerais, Brazil grow and flower multiple times throughout the year, independently of the season, contrasting with what happens in temperate regions. This could be due to the photoperiod consistently being inductive, with daylight hours below the described threshold (16.5 h critical). We observed that when the plants reached 7–9 nodes, the leaves began to transition from heart-shaped to trilobed-shaped, which could be indicative of the juvenile to adult transition. This could be related to the fact that the 5th node (in plants with 10 nodes) had the highest expression of miR156, while two miR172s increased in the 20th node (in plants with 25 nodes). Hop flowers appeared later, in the 25th or 28th nodes, and the expression of HlFT3 and HlFT5 was upregulated in plants between 15 and 20 nodes, while the expression of HlTFL3 was upregulated in plants with 20 nodes. These results indicate the role of axillary meristem age in regulating this process and suggest that the florigenic signal should be maintained until the hop plants bloom. In addition, it is possible that the expression of TFL is not sufficient to inhibit flowering in these conditions and promote branching. These findings suggest that the reproductive transition in hop under inductive photoperiodic conditions could occur in plants between 15 and 20 nodes. Our study sheds light on the intricate molecular mechanisms underlying hop floral development, paving the way for potential advancements in hop production on a global scale. [ABSTRACT FROM AUTHOR]

Tribulus terrestris is traditionally used to treat various diseases. The current research aimed to study the protective effects of methanolic extract of Tribulus terrestris (TT) against Spirotetramat (SPT) induced reproductive toxicity in adult male domestic pigeons (Columba livia domestica). For ten consecutive weeks and under an artificial photoperiod (19L: 5D), thirty male pigeons weighing approximately 309,20 ± 14,41g were divided equally into six groups as follows: CT served as the control, SPT group orally given with 15 mg/kg BW/day, TT100 and TT50 groups orally administrated with 100 and 50 mg/kg BW/day of TT respectively, and SPT+ TT100 and SPT + TT50 groups. Testicular volume and body weight were measured each two weeks. Whereas histopathological profile and luteinizing hormone (LH), folliclestimulating hormone (FSH), testosterone (T), total cholesterol (TC), LDL-C, HDL-C, and triglyceride (TG) were evaluated at week 10. The obtained data reveal that under a long photoperiod of 19L:5D, sexual activity lasted only 06 weeks in the control and TT groups, with a significant increase in testicular volume followed by spontaneous gonadal regression up to week 10. But testicular weights were superior in TT pigeons compared to the control during all experiments. However, the administration of SPT has suppressed gonadal growth and delayed photo-refractoriness. Sex hormones levels revealed a significant increase in LH and FSH levels in all groups compared to controls. However, a significant depletion in testosterone levels. Nevertheless, there was a substantial increase in TC, HDL-C, and LDL-C levels. Furthermore, co-administration of TT with SPT restored the lowered testicular volume, relative testicular weight, and T level but decreased the TC, HDL-C, and LDL-C levels. Finally, the histopathological investigation revealed degenerative changes in testes and gonad damage in the SPT group. However, TT reduced the damage induced by SPT. In conclusion, TT could be beneficial in preventing SPT reproductive toxicity and improving sex hormone synthesis. [ABSTRACT FROM AUTHOR]

Plant factories offer a promising solution to some of the challenges facing traditional agriculture, allowing for year-round rapid production of plant-derived foods. However, the effects of conditions in plant factories on metabolic nutrients remain to be explored. In this study, we used three rice accessions (KongYu131, HuangHuaZhan, and Kam Sweet Rice) as objectives, which were planted in a plant factory with strict photoperiods that are long-day (12 h light/12 h dark) or short-day (8 h light/16 h dark). A total of 438 metabolites were detected in the harvested rice grains. The difference in photoperiod leads to a different accumulation of metabolites in rice grains. Most metabolites accumulated significantly higher levels under the short-day condition than the long-day condition. Differentially accumulated metabolites were enriched in the amino acids and vitamin B6 pathway. Asparagine, pyridoxamine, and pyridoxine are key metabolites that accumulate at higher levels in rice grains harvested from the short-day photoperiod. This study reveals the photoperiod-dependent metabolomic differences in rice cultivated in plant factories, especially the metabolic profiling of taste- and nutrition-related compounds. [ABSTRACT FROM AUTHOR]

Wing dimorphism is regarded as an important phenotypic plasticity involved in the migration and reproduction of aphids. However, the signal transduction and regulatory mechanism of wing dimorphism in aphids are still unclear. Herein, the optimal environmental conditions were first explored for inducing winged offspring of green peach aphid, and the short photoperiod was the most important environmental cue to regulate wing dimorphism. Compared to 16 L:8 D photoperiod, the proportion of winged offspring increased to 90% under 8 L:16 D photoperiod. Subsequently, 5 differentially expressed microRNAs (miRNAs) in aphids treated with long and short photoperiods were identified using small RNA sequencing, and a novel miR‐3040 was identified as a vital miRNA involved in photoperiod‐mediated wing dimorphism. More specifically, the inhibition of miR‐3040 expression could reduce the proportion of winged offspring induced by short photoperiod, whereas its activation increased the proportion of winged offspring under long photoperiod. Meanwhile, the expression level of miR‐3040 in winged aphids was about 2.5 times that of wingless aphids, and the activation or inhibition of miR‐3040 expression could cause wing deformity, revealing the dual‐role regulator of miR‐3040 in wing dimorphism and wing development. In summary, the current study identified the key environmental cue for wing dimorphism in green peach aphid, and the first to demonstrate the dual‐role regulator of miR‐3040 in photoperiod‐mediated wing dimorphism and wing development. [ABSTRACT FROM AUTHOR]