Effect Of Different Photoperiods Research Articles

Effects of Different Photoperiods on Peripheral 5-Hydroxytryptamine Metabolism, Breast Muscle Glucose Metabolism, and Myopathies in Broilers.

Background: There is a close relationship between breast muscle glucose metabolism, peripheral 5-hydroxytryptamine (5-HT), and myopathies in animals. Here, this study aimed to investigate the effects of different photoperiods on peripheral 5-HT metabolism, white striping (WS), and wooden breast (WB) in broilers. Methods: A total of 216 healthy 5-day-old (d) Arbor Acres (AA) male broilers were randomly assigned to 12L:12D, 18L:6D, and 24L:0D photoperiods for 4 weeks. Results: Compared with the 12L:12D photoperiod, we found the WB score in broilers was significantly increased in the 18L:6D and 24L:0D photoperiod at week 4 (p < 0.05). Muscle glycogen was significantly reduced (p < 0.05) and glycolysis was promoted in the breast muscles of broilers under the 18L:6D and 24L:0D photoperiods at week 2 and 4. Peripheral 5-HT concentrations, the mRNA expression of tryptophan hydroxylase 1 (TPH1) and serotonin transporter (SERT) in the cecal mucosa, and 5-hydroxytryptamine receptor 2A (5-HTR2A) mRNA expression in the breast muscle of broilers significantly up-regulated in the 18L:6D and 24L:0D photoperiod at week 2 and 4 (p < 0.05). Conclusions: Our findings revealed that extending the photoperiod improved the breast muscle growth rate, but up-regulated 5-HT synthesis and secretion to higher peripheral 5-HT, induced breast muscle glucose metabolism disorder, and increased WB incidence rates in broilers.

Effects of Different Photoperiods on Growth Performance, Glucose Metabolism, Acetylcholine, and Its Relative Acetylcholine Receptor Modulation in Broiler Chickens.

Photoperiods are crucial environmental factors in the growth and health of modern intensive broiler chicken production. To date, the effects of different photoperiods on glucose metabolism, acetylcholine (ACh), and its relative acetylcholine receptor modulation in broilers remain elusive. Herein, we aimed to identify the effects of different photoperiods on regulating glucose metabolism, ACh, nicotinic acetylcholine receptor alpha 4 (α4 nAChR) mRNA, and M3 muscarinic acetylcholine receptor (M3 mAChR) modulation in broilers. A total of 216 healthy 5-day-old Arbor Acres (AA) male broilers was randomly assigned to 12L:12D, 18L:6D, and 24L:0D photoperiods for 4 weeks. The results show that, compared with the 12L:12D photoperiod, the 18L:6D and 24L:0D photoperiods significantly increase the average daily gain (ADG) and average daily feed intake (ADFI) of broilers (p < 0.05). However, the feed efficiency (FE) of broilers significantly decreased in the 18L:6D and 24L:0D photoperiods (p < 0.05). Moreover, compared with the 12L:12D photoperiod, the ACh concentrations and α4 nAChR mRNA expression levels in the hypothalamus and medulla oblongata of broilers significantly increased (p < 0.05); M3 mAChR mRNA expression levels in cecum significantly reduced in the 18L:6D photoperiod and the 24L:0D photoperiod (p < 0.05). Compared with the 12L:12D photoperiod, the serum glucose (GLU), serum insulin (INS), serum triglyceride (TG) levels, and homeostasis model assessment of insulin resistance (HOMA-IR) of broilers significantly enhanced in the 18L:6D and 24L:0D photoperiods (p < 0.05). Our results indicate that extending the photoperiod can promote the growth rate, ACh expression, and α4 nAChR mRNA expression of broilers while reducing the feed efficiency, inhibiting M3 mAChR mRNA expression, and inducing glucose metabolism disorders in broilers.

Effects of Different Photoperiods on the Transcriptome of the Ovary and Small White Follicles in Zhedong White Geese.

Photoperiod can regulate the broodiness of geese and thus increase their egg-laying rate. The laying performance of geese is mainly determined by ovary and follicle development. To understand the effect of photoperiod on the ovary and small white follicles, sixteen 220-day-old healthy female Zhedong white geese were randomly divided into two groups for long photoperiods (15L:9D) and short photoperiods (9L:15D). The geese were euthanized after two months of feeding, and their ovaries and follicles were collected for transcriptome sequencing. RNA-seq analysis identified 187 and 448 differentially expressed genes in ovaries and small white follicles of different photoperiod groups, respectively. A long photoperiod promotes high expression of SPP1, C6, MZB1, GP1BA, and FCGBP genes in the ovaries, and increases the expression of SPP1, ANGPTL5, ALPL, ZP1, and CHRNA4 genes in small white follicles. Functional enrichment analysis showed that photoperiod could affect respiratory system development, smooth muscle cell proliferation in ovaries, and extracellular matrix-related function in small white follicles. WGCNA revealed 31 gene modules, of which 2 were significantly associated with ovarian weight and 17 with the number of small white follicles. Our results provide a better understanding of the molecular regulation in the photoperiod affecting goose reproduction.

Effects of Different Photoperiods during Incubation on Post-Hatch Broiler Performance and Stress Response.

This study evaluated the subsequent effect of photoperiods during incubation on post-hatch growth and stress response of commercial broiler chickens. A total of 875 Ross 308 broiler breeder (48 weeks of age) eggs were hatched using different durations (0, 4, 8, 12, 16, 20, and 24 h a day) of dichromatic light [green and red (495 to 750 nm); 2700 K; 250 lux; SUNJIE; China] throughout the whole period of incubation. A total of 50 0-day-old hatched straight run broiler chicks from each photoperiod during incubation were used to evaluate subsequent growth performance (feed intake, body weight, and feed conversion ratio); stress parameters (physical asymmetry, tonic immobility, and vocalization,); welfare traits (feather score and gait score); carcass traits (live weight, dressed weight, carcass yield, liver weight, gizzard weight, heart weight, abdominal fat weight, breast weight, and leg weight); and serum chemistry (globulin, total protein, cholesterol, glucose, and uric acid). There were no influences of photoperiod during incubation on post-hatch growth, stress parameters, welfare, and carcass traits. Heart yield was higher in birds incubated under 20 h light than in those from the 16 h light group. Incubation under different lighting durations also altered blood biochemical profile but did not influence serum globulin and cholesterol levels. It was concluded that under experimental conditions, incubation of broiler eggs under different lighting durations did not impact subsequent post-hatch performance (21-35 d).

Interference of skeleton photoperiod in circadian clock and photosynthetic efficiency of tea plant: in-depth analysis of mathematical model.

The circadian system of plants is a complex physiological mechanism, a biological process in which plants can adjust themselves according to the day and night cycle. To understand the effects of different photoperiods on the biological clock of tea plants, we analyzed the expression levels of core clock genes (CCA1, PRR9, TOC1, ELF4) and photosynthesis-related genes (Lhcb, RbcS, atpA) under normal light (light/dark = 12h/12h, 12L12D) and took the cost function defined by cycle and phase errors as the basic model parameter. In the continuous light environment (24h light, 24L), the peak activity and cycle of key genes that control the biological clock and photosynthesis were delayed by 1-2h. Under a skeleton photoperiod (6L6D, 3L3D), the expression profiles of clock genes and photosynthesis-related genes in tea plants were changed and stomatal opening showed a circadian rhythm. These observations suggest that a skeleton photoperiod may have an effect on the circadian rhythm, photosynthetic efficiency and stomatal regulation of tea plants. Our study and model analyzed the components of circadian rhythms under different photoperiodic pathways, and also revealed the underlying mechanisms of circadian regulation of photosynthesis in tea plants.

Structure and function of vasa gene in gonadal gametogenesis of Pacific abalone

Pacific abalone (Haliotis discus hannai) is a marine gastropod mollusc with significant economic importance in both global fisheries and aquaculture. However, studies exploring the gonadal development and regulatory mechanisms of Haliotis discus hannai are limited. This study aimed to explore whether the vasa gene acted as a molecular marker for germ cells. Initially, the vasa gene was successfully cloned using the cDNA-end rapid amplification technique. The cloned gene had a 2478-bp-long open reading frame and encoded 825 amino acids. Then, a recombinant expression vector was constructed based on the Vasa protein, and an 87-kDa recombinant protein was prepared. Subsequently, a polyclonal antibody was prepared using the purified recombinant protein. The enzyme-linked immunosorbent assay (ELISA) confirmed the titer of the antibody to be ≥512 K. The immunohistochemical analysis revealed that Vasa was widely expressed in oogonia, Stage I oocytes, spermatogonia, and primary spermatocytes. The specific expression of Vasa in the hermaphroditic gonads of abalone was assessed using western blotting to investigate the effects of different photoperiods (12 L:12D, 24 L:0D, 18 L:6D, and 6 L:18D) on the gonadal development of abalone (P < 0.05), with higher expression levels observed in the ovarian proliferative and spermary maturing stages compared with other developmental stages (P < 0.05). Additionally, Vasa exhibited the highest expression in the spermary and ovary under a photoperiod of 18 L:6D (P < 0.05). These data demonstrated the key role of Vasa in developing germ cells in abalone. They shed light upon the molecular mechanism through which the photoperiod influenced Vasa expression and regulated gonadal development in abalone. The findings might provide theoretical references for analyzing the differentiation pattern of abalone germ cells and the genetic improvement and conservation of germplasm resources.

Variations in photoperiods and their impact on yield, photosynthesis and secondary metabolite production in basil microgreens

BackgroundThe effects of different photoperiods on plant phytochemical synthesis can be improved by adjusting the daily light integral. Photoperiod is one of the most important environmental factors that control growth, plant’s internal rhythm and the synthesis of secondary metabolites. Information about the appropriate standard in terms of photoperiod for growing basil microgreens as one of the most important medicinal plants is limited. In this study, the effects of five different photoperiods, 6 (6 h × 3 cycles), 8 (8 h × 2 cycles), 16, 18, and 24 h day− 1 on the yield, photosynthesis and synthesis of secondary metabolites of three cultivars and one genotype of basil microgreens in floating system were evaluated. The purpose of this research was to determine the feasibility of using permanent light in growing basil microgreens and to create the best balance between beneficial secondary metabolites and performance.ResultsThe results showed that the effects of photoperiod and cultivar on all investigated traits and their interaction on photosynthetic pigments, antioxidant capacity, total phenolic compounds, proline content and net photosynthesis rate were significantly different at the 1% level. The highest levels of vitamin C, flavonoids, anthocyanins, yield and antioxidant potential composite index (APCI) were obtained under the 24-h photoperiod. The highest antioxidant capacity was obtained for the Kapoor cultivar, and the highest total phenolic compound and proline contents were measured for the Ablagh genotype under a 24-h photoperiod. The highest yield (4.36 kg m− 2) and APCI (70.44) were obtained for the Ablagh genotype. The highest nitrate content was obtained with a photoperiod of 18 h for the Kapoor cultivar. The highest net photosynthesis rate was related to the Violeto cultivar under a 24-hour photoperiod (7.89 μmol CO2 m− 2 s− 1). Antioxidant capacity and flavonoids had a positive correlation with phenolic compounds and vitamin C. Yield had a positive correlation with antioxidant capacity, flavonoids, vitamin C, APCI, and proline.ConclusionsUnder continuous light conditions, basil microgreens resistance to light stress by increasing the synthesis of secondary metabolites and the increase of these biochemical compounds made basil microgreens increase their performance along with the increase of these health-promoting compounds. The best balance between antioxidant compounds and performance was achieved in continuous red + blue light. Based on these results, the use of continuous artificial LED lighting, due to the increase in plant biochemical with antioxidant properties and yield, can be a suitable strategy for growing basil microgreens in floating systems.

Effects of Photoperiod and Light Quality on Germination and Growth of Camellia sinensis 'HuangKui'.

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.

The Photoperiod Significantly Influences the Growth Rate, Digestive Efficiency, Immune Response, and Antioxidant Activities in the Juvenile Scalloped Spiny Lobster (Panulirus homarus)

This study aimed to elucidate the effects of different photoperiods (0 L:24 D, 6 L:18 D, 12 L:12 D, 18 L:6 D, 24 L:0 D, “Light (L) and Dark (D)”) on the growth performance and physiological responses of the juvenile scalloped spiny lobster (Panulirus homarus). Over a period of 56 days, parameters such as growth rate, digestive enzyme, immune enzyme, and antioxidant enzyme were meticulously evaluated in 90 lobsters subjected to these varying light conditions. The present study found no significant differences in survival rate (SR), molting frequency (MF), and meat yield production (MYP) among the various photoperiod treatments (p &gt; 0.05). Notably, the highest weight gain rate (WGR) and specific growth rate (SGR) were observed under a 12 L:12 D photoperiod. In the continuous dark phase (0 L:24 D), pepsin (PEP) activity remained high in gastric tissues, while trypsin (TRYP) and chymotrypsin (CHT) activities reached the highest in hepatopancreas tissues. The α-amylase (AMS) activity in the hepatopancreas was most elevated under 18 L:6 D, and the optimal lipase (LPS) activity was recorded under 12 L:12 D. The activity of acid phosphatase (ACP) in the hepatopancreas was highest in the absence of light (0 L:24 D), whereas the activities of alkaline phosphatase (AKP) and lysozyme (LZM) were most effective under the 12 L:12 D photoperiod. The total antioxidant capacity (T-AOC), along with catalase (CAT) and superoxide dismutase (SOD) activities of the hepatopancreas reached the highest at 12 L:12 D. The highest activity of glutathione peroxidase (GSH-Px) was seen under 18 L:6 D. The concentration of malondialdehyde (MDA), a marker of oxidative stress, was found to be highest under 12 L:12 D. Consequently, this specific photoperiod is essential for achieving optimal growth and maintaining appropriate physiological balance in the scalloped spiny lobster during aquaculture. These findings provide a foundational guideline for establishing the lighting environment in the farming of the juvenile scalloped spiny lobster.

Effects of different photoperiods on the growth and survival of cultured edible frog Hoplobatrachus occipitalis (Günther 1858) from tadpole to full metamorphosis

ABSTRACT Three photoperiods designed as 24L:0D; 0L:24D and 12L:12D were used to culture Hoplobatrachus occipitalis (Günther 1858) tadpoles to evaluate the growth performance and survival rate. One hundred and eighty tadpoles were distributed into the three photoperiodic ponds for 20 weeks and fed with duck weed. The frogs reared using the 0L:24D photoperiod had significantly higher growth performance, survival rate and metamorphosis where the tadpoles reached full metamorphosis after 20 weeks, than the other two photoperiods (P < .05.) Full metamorphosis of the tadpoles was seen when the limbs have been fully formed, tails and gills have been completely absorbed, the eyes become bulgy and they are completely out of water breathing by their lungs. Higher growth performance, survival rate and metamorphosis in 0L:24D photoperiod could be attributed to complete utilization of food, low ammonia concentration and high dissolved oxygen. Commercial aquaculture of H. occipitalis tadpoles should be done in 0L:24D to obtain complete metamorphosis, survival and faster growth in less time. Using 0L:24D to culture the tadpoles and releasing them into the wild will decrease overexploitation of the species, thereby aiding in their conservation.

Effects of Different Photoperiods on the Growth and Nutritional Characteristics of Two Celery Cultivars in Plant Factory

Effects of Different Photoperiods on the Growth and Nutritional Characteristics of Two Celery Cultivars in Plant Factory

Effect of different photoperiods on the biology of immatures and adults of Anopheles darlingi (Diptera: Culicidae)

Studies on the mosquito Anopheles darlingi Root (Diptera: Culicidae) are essential since it is the main vector of human malaria in the Brazilian Amazon. Photoperiod affects several biological variables of mosquitoes including motor, e.g., mating behavior, and oviposition and behavioral, e.g., consuming sugar and blood diets, activities, therefore, this work investigated the effect of different photoperiods on the biology of this species. Mosquitoes were reared under three different treatments: (i) 12 L:12 D, (ii) 24 L:0 D (constant light), and (iii) 0 L:24 D (constant darkness). Fifty larvae per tray were reared under different light periods and fed ground fish food. Survival and larval development times, emergence and pupation rates, the male-to-female ratio, and adult longevity were recorded. The use of different photoperiods affected several biological parameters of A. darlingi. The 24 L:0 D and 0 L:24 D treatments resulted in higher mortality, whereas constant light increased larval development time. The male-to-female ratio was greatly reduced under constant light conditions, but adult longevity was not affected by the photoperiods used. Thus, unnatural light conditions (complete light or complete darkness) result in suboptimal mosquito rearing.

Transcriptome profiles reveal gene regulation of ginger flowering induced by photoperiod and light quality

BackgroundUnder natural conditions, ginger (Zingiber officinale Rosc.) rarely blossom and has seed, which limits new variety breeding of ginger and industry development. In this study, the effects of different photoperiods and light quality on flowering induction in ginger were performed, followed by gene expression analysis of flower buds differentiation under induced treatment using RNA-seq technology.ResultsFirst, both red light and long light condition (18 h light/6 h dark) could effectively induce differentiation of flower buds in ginger. Second, a total of 3395 differentially expressed genes were identified from several different comparisons, among which nine genes, including CDF1, COP1, GHD7, RAV2-like, CO, FT, SOC1, AP1 and LFY, were identified to be associated with flowering in induced flower buds and natural leaf buds. Aside from four down-regulated genes (CDF1, COP1, GHD7 and RAV2-like), other five genes were all up-regulated expression. These differentially expressed genes were mainly classified into 2604 GO categories, which were further enriched into 120 KEGG metabolic pathways. Third, expression change of flowering-related genes in ginger indicated that the induction may negatively regulated expression of CDF1, COP1, GHD7 and RAV2-like, and subsequently positively regulated expression of CO, FT, SOC1, LFY and AP1, which finally led to ginger flowering. In addition, the RNA-seq results were verified by qRT-PCR analysis of 18 randomly selected genes, which further demonstrated the reliability of transcriptome analysis.ConclusionThis study revealed the ginger flowering mechanism induced by light treatment and provided abundant gene information, which contribute to the development of hybrid breeding of ginger.

Effects of different photoperiods on growth and ovarian development and maturation of silver pomfret Pampus argenteus.

Photoperiod has a great influence on the growth and ovarian development and maturation of fishes. To analyse the effects of photoperiod on growth and ovarian development of an important marine economic fish, silver pomfret Pampus argenteus, short photoperiod group (L:D = 8:16), control group (L:D = 12:12) and long photoperiod group (L:D = 18:6) were set up for 60 days. The growth performance, ovarian development, changes in hormones and key enzyme activities in the hypothalamic-pituitary-gonadal (HPG) axis and expressions of key regulatory genes in the HPG axis were studied under different photoperiod conditions. The results showed that the final weight gain, body weight index, specific growth rate for weight, specific growth rate for length and average daily growth were the highest in the long photoperiod group, and the feed conversion rate was the lowest. Under long photoperiod condition, gonado-somatic index and hepato-somatic index were higher, ovarian maturity was better and expressions of HPG axis-related regulatory genes foxl2a, foxl2b, cyp19a1a, cyp19a1b, kiss, gpr54-2, gnrh2, fsh and lh were higher. When compared with the other two groups, in the long photoperiod group, the change trend of estradiol (E2) was consistent with those of luteinizing hormone, melatonin (MT) and kisspeptin, and the levels were higher on the 20th and 50th days. These results indicate that prolongation of the photoperiod can improve the growth performance of P. argenteus and promote ovary development and maturation. The authors speculate that photoperiod may regulate the ovarian activity of P. argenteus through MT and kisspeptin/gpr54 signalling pathways. The results show that photoperiod can regulate the ovarian development of P. argenteus, which would help in breaking the seasonal restrictions of animals and regulating an animal's reproductive cycle.

Moving Away from 12:12; the Effect of Different Photoperiods on Biomass Yield and Cannabinoids in Medicinal Cannabis

The standard practice to initiate flowering in medicinal cannabis involves reducing the photoperiod from a long-day period to an equal duration cycle of 12 h light (12L)/12 h dark (12D). This method reflects the short-day flowering dependence of many cannabis varieties but may not be optimal for all. We sought to identify the effect of nine different flowering photoperiod treatments on the biomass yield and cannabinoid concentration of three medicinal cannabis varieties. The first, "Cannatonic", was a high cannabidiol (CBD)-accumulating line, whereas the other two, "Northern Lights" and "Hindu Kush", were high Δ9-tetrahydrocannabinol (THC) accumulators. The nine treatments tested, following 18 days under 18 h light/6 h dark following cloning and propagation included a standard 12L:12D period, a shortened period of 10L:14D, and a lengthened period of 14L:10D. The other six treatments started in one of the aforementioned and then 28 days later (mid-way through flowering) were switched to one of the other treatments, thus causing either an increase of 2 or 4 h, or a decrease of 2 or 4 h. Measured parameters included the timing of reproductive development; the dry weight flower yield; and the % dry weight of the main target cannabinoids, CBD and THC, from which the total g cannabinoid per plant was calculated. Flower biomass yields were highest for all lines when treatments started with 14L:10D; however, in the two THC lines, a static 14L:10D photoperiod caused a significant decline in THC concentration. Conversely, in Cannatonic, all treatments starting with 14L:10D led to a significant increase in the CBD concentration, which led to a 50-100% increase in total CBD yield. The results show that the assumption that a 12L:12D photoperiod is optimal for all lines is incorrect as, in some lines, yields can be greatly increased by a lengthened light period during flowering.

Effects of different photoperiods and feeding regimes on immune response, oxidative status, and tissue damage in juvenile rainbow trout (Oncorhynchus mykiss)

A three-month culture experiment was conducted to investigate the effects of the feeding regime on liver health, non-specific immunity, and apoptosis of juvenile rainbow trout under constant light conditions. A total of six experimental groups contained two photoperiods [LL (24L:0D) and LD (12L:12D)] and three feeding regimes [R (random feeding), D (mid-dark stage feeding), L (mid-light stage feeding)], defined as R-LL, D-LL, L-LL, R-LD, D-LD, L-LD. The experiment results revealed a significantly higher alanine aminotransferase (ALT) level in the nocturnal feeding group (D-LD) and significantly higher aspartate aminotransferase (AST) in the R-LL and D-LL groups, indicating possible liver damage in these groups. In addition, high serum levels of immunoglobulins M (IgM), complement 3 (C3), and complement 4 (C4) were observed in the LL (compared to LD), R (LL conditions), and D (LD conditions) groups, suggesting that stress may be present in these groups. Meanwhile, under LL, high cytokine genes (tnf-α, il-1β, il-6, and il-8) expression were observed in the liver and intestine of the L group, possibly reflecting a stronger immune response. In the liver, high malondialdehyde (MDA) content was observed in the LL (compared to LD), R (LD conditions), and D (LL conditions) groups, suggesting that these groups were subjected to oxidative damage. Further, higher apoptosis genes (cytc and bcl-2) expression in the liver was detected in the R and D-LD groups. The highest level of hepatic apoptotic cells was also observed in the D-LD group. Taken together, long-term exposure to LL, random feeding, and nocturnal feeding can cause oxidative damage to juvenile rainbow trout, leading to hepatocyte apoptosis, while scheduled diurnal feeding can alleviate the oxidative damage caused by LL.

Morphological, Biochemical, and Physiological Response of Butterhead Lettuce to Photo-Thermal Environments

Plants actively respond to changes in photoperiods, light intensities, and temperatures; an interplay of these three factors can result in increased biomass, growth, and improved plant morphology. This study aimed to investigate the effects of different photoperiods, light intensities, and day/night temperatures on the growth and quality of glasshouse-grown lettuce, as well as to determine the optimal photo-thermal conditions. Two separate experiments were conducted; in the first experiment, the effects of photoperiods (11, 14, and 17 h d−1) and light intensities (150, 200, 250, and 300 μmol m−2 s−1 PPFD) were investigated. In the second experiment, the effects of day/night temperature combinations (15/20, 20/20, 25/20, and 30/20 °C) were assessed. The highest growth, biochemical, and physiological attributes of lettuce were obtained either at 14 or 17 h d−1 + 200 and 250 μmol m−2 s−1 PPFD. Lettuce plants grown at a 20/20 °C day/night temperature also showed promising results compared to other temperature combinations. Based on a principal component analysis and factor analysis of mixed data analyses, most of the lettuce attributes showed a negative correlation with an 11 h d−1 photoperiod and a positive correlation with 14 and 17 h d−1 photoperiods. The most positive responsive attributes to higher light intensity were leaf fresh weight:root fresh weight ratio, root dry, and water use efficiency. An increase in the day/night temperature significantly affected the N, P, K, root fresh weight:leaf fresh weight ratio, E, Pn, and root dry weight. Our findings suggest that the growth, biochemical, and physiological attributes of lettuce significantly increased to a certain level of light intensity (200 and 250 μmol m−2 s−1 PPFD), photoperiod (14 and 17 h d−1), and day/night temperature (20/20 °C), referred to as an effective combination.

Circadian activity in different photoperiod (12L: 12 D) and (8L: 16D) in passerine finches

Circadian rhythms are more synchronized in birds than mammals. Circadian clock functions as a timing reference allow organisms fluctuations in their environments and are the basis for the transduction of seasonality from photoperiod. The present study was performed to determine the effect of constant dim and bright light illumination on circadian behavior of baya weaver bird ( Ploceus philippinus), black-headed munia ( Lonchura malaca malaca), and red-headed bunting ( Emberiza bruniceps). It analyzed the data of locomotors activity of these under the effect of different photoperiods (12L: 12D and 8L: 16D) for a period of 30 days. In the captivity, birds were acclimatized for 4 weeks and were subjected to photoperiodic chambers (60×45×35 cm3) providing short-day conditions (8h light: 16h darkness; 8L:16D). Total activity profile was observed for 30 days under 12L: 12D and 8L: 16D photoperiod. Under 12 L: 12D photoperiod, significant response was observed in two of the four birds in daily profile of baya weaver bird and also in black-headed munia but the marginal significant response noticed in one of the four birds under 8L: 16D. The comparison of day and night total activity count in baya weaver bird and black-headed munia showed the maximum activity in weaver bird under 12L: 12D photoperiod.

Effects of different photoperiods on growth performance, daily rhythm of growth axis-related genes, and hormones in Nile tilapia (Oreochromis niloticus)

The aim of this study was to explore the effects of different photoperiods on the daily rhythm of the growth axis of Nile tilapia (Oreochromis niloticus). Fish were subjected to five photoperiod treatments in this experiment: [light (L) dark (D) ratio: 0 L:24D, 8 L:16D, 12 L:12D, 16 L:8D, 24 L:0D, light intensity 1000 lx]. The growth performance and the daily rhythm of the transcript levels of growth axis-related genes (gh, ghr1, pacap1b, igf-1, igf-1ra) and the contents of growth-related hormones (GH, IGF-1 protein) were analyzed after 4 weeks of culture in the different treatments. To allow for comparisons among treatments, the start of the light period was set to 0 h Zeitberger time (0 h ZT). The results showed that the weight-specific growth rate and daily weight gain of Nile tilapia were highest under 16 L:8D. Under 12 L:12D, the transcript levels of ghr1, igf-1, and igf-1ra and the IGF-1 protein content in the liver showed a clear daily rhythm, and the peak in the daily oscillation (acrophase) was at ZT 7.83 h, ZT 23.53 h, ZT 2.54 h, and ZT 5.91 h, respectively. When the photoperiod changed, ghr1 lost its daily rhythm. Compared with the acrophase under 12 L:12D, the acrophase of igf-1 delayed to ZT 1.71 h under 8 L:16D and ZT 0.06 h under 16 L:8D; that of igf-1ra was delayed to ZT 16.19 h under 16 L:8D and ZT 16.57 h under 24 L:0D; and that of IGF-1 protein was delayed to ZT 8.23 h under 8 L:16D and ZT 8.43 h under 16 L:8D. These results indicated that 16 L:8D was most suitable for the growth of Nile tilapia, because this photoperiod increased the amplitude of IGF-1 including the transcript level and protein and advanced their acrophase. These results shed light on the daily rhythm of growth axis of Nile tilapia, and provided a theoretical basis for optimizing the industrial culture conditions and increasing the yield of this important aquaculture fish species.

Effects of different photoperiods on flower opening, flower closing and circadian expression of clock-related genes in Iris domestica and I. dichotoma.

The circadian clock can entrain to forced light-dark cycles by adjusting the phases and periods of flower opening and closing in ephemeral flowers. The responses of circadian rhythms to the same light conditions differ from species. However, the differences in internal genetic mechanisms underlying the different responses between species remain unclear. Iris domestica and I. dichotoma have ephemeral flowers and significantly divergent flower opening and closing times. The effects of different photoperiods (continuous darkness, 4L20D, 8L16D, 12L12D, 16L8D, 20L4D and continuous white light) on flower opening and closing, and expression patterns of seven genes (CRYPTOCHROME 1, PHYTOCHROME B, LATE ELONGATED HYPOCOTYL, PSEUDO RESPONSE REGULATOR 95, PHYTOCHROME INTERACTING FACTOR 4-like, SMUX AUXIN UP RNA 64-like and senescence-associated gene 39-like) involved in the circadian regulation of flower opening and closing were compared between I. domestica and I. dichotoma. Flower opening and closing in the two species exhibited circadian rhythms under continuous darkness (DD), but showed arrhythmia in continuous white light (LL). In the two species, keeping robust rhythms, strong synchronicity, rapid progressions of flower opening and closing and reaching full opening stage required a dark period longer than 4h. In light-dark cycles with dark periods longer than 4h, flower opening and closing times of the two species delayed with the delay of dawn, and the degree to which flower opening time varies with the time of dawn was greater in I. dichotoma than in I. domestica. The arrhythmia of flower opening and closing under 20L4D and LL would result from the arrhythmic output signals rather than arrhythmia of oscillators and photoreceptors. The different responses of the two species to the change of photoperiods would be caused by the transcriptional differences of genes in the output pathway of circadian clock system rather than in the input pathway or oscillators.