Light Photoperiod Research Articles

Revealing the adaptation mechanism of different color morphs of sea cucumber Apostichopus japonicus to light intensities from the perspective of metabolomics

Global warming has multi-dimensional and complex impacts on the Earth's system, among which changes in light intensities cannot be overlooked. Sea cucumbers are a marine biological resource with significant economic and ecological value. Their presence and activity help maintain the balance and stability of marine ecosystems. The variation in light intensities have important ecological effects on sea cucumbers. Light intensities can alter the synthesis and degradation of metabolic substances within the bodies of Apostichopus japonicus by changing their body color. Their changes affect the production of microorganisms in the environment, thereby achieving the goal of bioremediation. This study investigated metabolic variations in green, purple, and white sea cucumber Apostichopus japonicus under different light conditions (0 lx and 910 lx) with a 12-h light and 12-h dark photoperiod. The findings indicated that the sea cucumbers displayed more diverse metabolic alterations under 910 lx illumination compared to 0 lx. Specifically, these color morphs primarily responded to changes in light intensities through “tryptophan metabolism” and “biosynthesis of steroid hormones”. Additionally, high light intensities environment exacerbated the consumption of fatty acids by sea cucumbers. Different color morphs of sea cucumbers have differences in key metabolites in response to changes in light intensities. Green and white sea cucumbers primarily adapt to environment through phospholipids, while purple sea cucumbers mainly utilize fatty acids. These results enhance our comprehension of how sea cucumbers adapt ecologically to varying light intensities, and they offer valuable insights for systematically uncovering the regulatory processes that marine animals employ in response to environmental changes.

Growing Tomato Seedlings Suitable for Mechanical Grafting under Regulated Light Regime

Abstract: The uniformity of growth and mechanical properties of grafted seedlings affect the quality of mechanical grafting operations. The growth uniformity of grafted seedlings in a greenhouse will be poor due to the uneven and unstable light and temperature conditions. Plant factories can cultivate grafted seedlings in the most suitable environment by regulating environmental parameters such as light and temperature. The aim of this study was to investigate the impact of the light conditions on tomato seedlings in plant factory and to develop an optimal cultivation light formula. The effects of light intensity (50, 100, 150, 200, and 250 μmol m−2 s−2) and photoperiod (10, 12, 14, 16, and 18 h a day(h/d)) on the morphological and mechanical properties of tomato seedlings were experimentally investigated. Orthogonal experiments were conducted involving light quality (R:B = 75:25, R:B = 50:50, and R:B = 25:75), light intensity (150 μmol m−2 s−2, 200 μmol m−2 s−2, and 250 μmol m−2 s−2), and photoperiod (14, 16, and 18 h/d) as independent variables to determine the optimal combination. Finally, a comparative grafting experiment was conducted between the seedlings cultivated using the optimal light formula and commercially available seedlings. The result showed that increasing light intensity inhibited hypocotyl length and promoted seedling stem growth, and excessive light intensity decreased seedling mechanical properties. The optimal light intensity for rootstocks is 200 μmol m−2 s−2, and the optimal light intensity for scions is 250 μmol m−2 s−2. Shortening the photoperiod would promote hypocotyl growth and inhibit seedling stem elongation. Different photoperiods had a significant impact on the mechanical properties of tomato seedlings. The most suitable photoperiod for rootstocks was 18 h/d and for scions was 16 h/d. The most suitable light formula was R:B = 50:50, 250 μmol m−2 s−2, 18 h/d. By analyzing the experimental results, the mechanical properties of seedlings grown by the regulated light environment were better than those of commercially available seedlings, and the success rate of mechanical grafting was 7% higher. Overall, in plant factories compared to commercially available tomato seedlings, tomato seedlings cultivated by the regulated light environment were more suitable for mechanical grafting. This research result provides theoretical support for subsequent research on grafting machinery.

The modified artificial cohort method for three dominant pelagic copepods in the northern North Pacific revealed species-specific differences in the optimum temperature

The most concerning recent ocean changes in temperature issues are known as marine heat waves. Under these conditions, it is important to evaluate the effects of temperature on zooplankton. In this study, we investigated the growth rates of three dominant copepod species (Eucalanus bungii, Metridia pacifica, and Neocalanus plumchrus) in the northern North Pacific under three different temperature conditions (3, 7, and 11°C) using an artificial cohort method. Experimental conditions for 42 hour incubations were set to light intensity and photoperiod corresponding to 50 m depth. The dissolved oxygen solubility after rearing ranged from 69.2% to 102.1%, suggesting sufficient conditions for copepod growth. Chlorophyll a increased in 83% of the experiments, indicating that the food conditions were sufficient for the copepods. The mean proportion of dead specimens evaluated using neutral red was 10.2%, corresponding with the reported values in the field. Thus, it can be concluded that the laboratory-rearing conditions used in this study provided sufficient food, and the only effect evaluated would be that of the three different temperatures. Since the developmental time for each stage is longer than the rearing period, it is important to conduct experiments with a large number of individuals to obtain accurate growth rate results. The specific growth rates of E. bungii and M. pacifica increased with increasing temperature. In contrast, N. plumchrus showed the highest growth rate under moderate water temperature conditions. In terms of weight units (dry, carbon, and nitrogen), the carbon weight-specific growth rates were higher than those of the other two units, a common characteristic of the three species. This reflected lipid accumulation during the late copepodite stages. The interspecies differences in growth rate responses to water temperature reflect species-specific differences in temperature tolerance or the optimum temperature for each species. As E. bungii and M. pacifica reproduce near the surface layer through income breeding, their temperature tolerance or optimum temperature is expected to be high. However, because the reproduction of N. plumchrus occurs in the cold deep layer by using capital breeding, its temperature tolerance and optimum temperature would be lower than those of the former two species.

Comparative transcriptome analysis reveals molecular mechanisms of the effects of light intensity and photoperiod on ovarian development in Procambarus clarkii (Girard, 1852)

Procambarus clarkii (Girard, 1852) has important economic value in China and internationally. In this research, the comparative transcriptome analysis was used to reveal molecular mechanisms of influences of photoperiod and light intensity on ovarian development in P. clarkii for the first time. Some genes (such as laminin, collagen, integrin beta, catenin) and pathways (including TGF-beta signaling pathway, focal adhesion, ECM–receptor interaction) associated with ovarian development and oocyte maturation were significantly upregulated. Some genes related to circadian clock (such as CLK, PER) were identified in this research. The results indicated that when light intensity or photoperiod increased, P. clarkii could up-regulate the expression levels of the laminin and collagen, thereby synthesizing related proteins, promoting meiosis of the oocytes, thus increasing the number of oocytes in the ovary. At the same time, P. clarkii could up-regulate the expression levels of integrin beta, integrin alpha 6, and diacylglycerol to synthesize related proteins, thereby promoting the formation of proteins and fats such as triglycerides, these proteins and fats can provide material basis for maturation and development of oocytes, resulting in oocyte maturation and ovarian development. P. clarkii could synthesize related proteins by upregulating expression levels of genes (such as catenin), these proteins or hormones can adhere to other actins (such as integrins), thereby stabilizing the morphology of the oocytes and ensuring normal development. Meantime, the increase in light intensity or photoperiod could cause release GSH and VTG, resulting in oocytes development and maturation. The data in this research can reveal molecular mechanisms of impacts of photoperiod and light intensity on oocyte maturation and ovarian development in P. clarkii, can offer crucial genomic data for studying developmental mechanisms of ovary and oocyte in crustacean.

Sweet cherries modulate thyroid hormones and hepatic glucose metabolism in F344 rats in a photoperiod-dependent manner

Sweet cherry intake affects oxidative stress and hepatic lipid metabolism, depending on composition, mainly (poly)phenol profile and daylight length. Thyroid hormones (TH) respond to daylight changes and regulate the hepatic glucose metabolism. This study investigated whether cherries with different phenolic hallmarks exhibit seasonal responses to TH and hepatic glucose metabolism. Fischer 344 rats fed a standard diet were chronically exposed to L6 (6 h light), L12 (12 h light), and L18 (18 h light) photoperiods and were supplemented with two sweet cherries (Ch1 and Ch2). Serum TH levels and glucose metabolism-related metabolites were affected by both the cherry composition and photoperiod. Thus, Ch1 and Ch2 reduced serum T3 levels in L6, whereas Ch2 increased it in L18, nullifying the photoperiod effect. Moreover, although photoperiod was the main factor affecting the hepatic expression of gluconeogenesis-related genes, Ch1 exerted effects mainly on L6 photoperiod and Ch2 on L18, tending to cancel out the photoperiod effects.

Violet Light Effects on the Circadian Rest-Activity Rhythm and the Visual System.

Rooms illuminated by "black light" (<400 nm wavelength) has become popular, but there is not enough scientific evidence to support its implementation. This study aims to assess the effects of violet light (392 nm) on the circadian rest-activity rhythm and the visual system through animal experimentation. Five groups of four mice were exposed to different white light, violet light, and dark periods, and their circadian rhythm was analyzed by measuring the circadian period using rest-activity cycles. Electroretinographic recordings and structural analysis of the retina were also performed on experimental animals. Our study demonstrates that mice present normal circadian activity during exposure to violet light, taking rest not only under white light but under violet lighting periods. However, mice suffered a decrease in electrical retinal response after exposure to violet light as measured by electroretinography. Nevertheless, no structural changes were observed in the retinas of the animals under different lighting conditions. Violet light elicits circadian rest-activity rhythm in mice but alters their visual function, although no structural changes are observed after short periods of violet light exposure.

Optimization of phycobiliprotein biosynthesis in thermotolerant cyanobacteria through light parameter adjustment

This study addressed the optimization of biomass and C-phycocyanin (C-PC) concentration and its purity in the thermotolerant cyanobacterium Potamosiphon sp by adjusting key light quality parameters. Custom design and Central Composite Design experimental designs were employed, using LEDs light intensity, wavelength, and photoperiod. The results demonstrated that these lighting parameters significantly influence biomass and C-phycocyanin production, achieving up to a 100 % increase in phycocyanin accumulation and biomass production and a 50 % improvement in purity index compared to conventional white light under optimal conditions of Red:Blue light (3:1), Intensity (283 μmol m−2 s−1), and photoperiod (17.8 H light). The findings support the use of specific LEDs wavelengths that optimize the performance of production processes and the quality of products derived from cyanobacteria, such as high-value phycobiliproteins.

Zygotic Exposure to Venlafaxine Disrupts the Circadian Locomotor Activity Behaviour in Zebrafish Larvae.

The antidepressant venlafaxine, a selective serotonin and norepinephrine reuptake inhibitor, is commonly prescribed to treat major depressive disorder and is found at high concentrations in the aquatic environment. Concerns have been raised related to the health of aquatic organisms in response to this nontargeted pharmaceutical exposure. For instance, we previously demonstrated that exposure to venlafaxine perturbs neurodevelopment, leading to behavioural alterations in zebrafish (Danio rerio). We also observed disruption in serotonin expression in the pineal and raphe, regions critical in regulating circadian rhythms, leading us to hypothesize that zygotic exposure to venlafaxine disrupts the circadian locomotor rhythm in larval zebrafish. To test this, we microinjected zebrafish embryos with venlafaxine (1 or 10 ng) and recorded the locomotor activity in 5-day-old larvae over a 24-h period. Venlafaxine deposition reduced larval locomotor activity during the light phase, but not during the dark phase of the diurnal cycle. The melatonin levels were higher in the dark compared to during the light photoperiod and this was not affected by embryonic venlafaxine deposition. Venlafaxine exposure also did not affect the transcript abundance of clock genes, including clock1a, bmal2, cry1aand per2, which showed a clear day/night rhythmicity. A notable finding was that exposure to luzindole, a melatonin receptor antagonist, decreased the locomotor activity in the control group in light, whereas the activity was higher in larvae raised from the venlafaxine-deposited embryos. Overall, zygotic exposure to venlafaxine disrupts the locomotor activity of larval zebrafish fish during the day, demonstrating the capacity of antidepressants to disrupt the circadian rhythms in behaviour. Our results suggest that disruption in melatonin signalling may be playing a role in the venlafaxine impact on circadian behaviour, but further investigation is required to elucidate the possible mechanisms in larval zebrafish.

Effects of light colors on the growth, body color changes, and phototactic behaviors of green, purple, and white sea cucumbers, Apostichopus japonicus

The sea cucumber (Apostichopus japonicus) is a high valuable species in Chinese aquaculture. Light significantly impacts the life cycle of sea cucumbers. However, existing studies mainly focus on the effect of light intensity and photoperiod on adult green sea cucumbers, with fewer studies on light color and inconsistent results. Research on the photoreceptive responses of different color morphs is still insufficient. Therefore, this study aims to explore the physiological and behavioral effects of different light colors on various color morphs (green, purple, white) of sea cucumbers. The results showed that short-wavelength light inhibits sea cucumber growth, while long-wavelength light and darkness promote higher growth rates. Green sea cucumbers adapted best to light stress, followed by purple and white morphs. Purple sea cucumbers grew better under long-wavelength light and darkness. Under low light, color changes in sea cucumbers were minimal. Sea cucumbers exhibited negative phototaxis to all light colors, with stronger reactions to blue and purple light, leading to stacking behavior. They aggregated less under red and yellow light, using tentacle contact to reduce light exposure. White sea cucumbers showed the most aggregation under light. The results provide a theoretical basis for further research on sea cucumber photoreception, new insights into environmental adaptation, and information for aquaculture improvement.

Effects of Incubation Light on Behaviour, Growth Performance, Blood Parameters, and Digestive Enzymes in Post-Hatch Layer Chicks.

Manipulation of light during incubation may have an effect on post-hatch chicks through the role of prenatal stage. The effects of providing different wavelengths of light (white, blue, and green lights, dark as control) during incubation on the growth performance, organ development, immune response, stress related hormones, digestive enzymes and behaviour of post-hatch chicks were investigated for 1-42 days. A total of 60 chicks per light treatment in three batches were used in this study. The results showed that the percentage of chicks accessing to feed and water resources appeared not to be affected by incubation light. Chicks hatched under white light were found to have a growth advantage (p < 0.05). The weight of organs (except thymus), IgA, IgY, IgM and heterophil to lymphocyte (H/L) ratio for post-hatch chicks were not affected by incubation light (p > 0.05). Thymus weight was reduced in chicks incubated under blue light compared to dark incubation (p < 0.05). The jejunum amylase and ileum lipase activities were significantly affected by the light treatments (p < 0.01). All light incubation chicks had stable plasma corticosterone levels and may have better ability to cope with environmental changes. Hence, white light photoperiod incubation may have potential to improve post-hatch chicks' growth performance and environmental adaptability.

Ribosome Pausing Negatively Regulates Protein Translation in Maize Seedlings during Dark-to-Light Transitions.

Regulation of translation is a crucial step in gene expression. Developmental signals and environmental stimuli dynamically regulate translation via upstream small open reading frames (uORFs) and ribosome pausing. Recent studies have revealed many plant genes that are specifically regulated by uORF translation following changes in growth conditions, but ribosome-pausing events are less well understood. In this study, we performed ribosome profiling (Ribo-seq) of etiolated maize (Zea mays) seedlings exposed to light for different durations, revealing hundreds of genes specifically regulated at the translation level during the early period of light exposure. We identified over 400 ribosome-pausing events in the dark that were rapidly released after illumination. These results suggested that ribosome pausing negatively regulates translation from specific genes, a conclusion that was supported by a non-targeted proteomics analysis. Importantly, we identified a conserved nucleotide motif downstream of the pausing sites. Our results elucidate the role of ribosome pausing in the control of gene expression in plants; the identification of the cis-element at the pausing sites provides insight into the mechanisms behind translation regulation and potential targets for artificial control of plant translation.

Light Flux Density and Photoperiod Affect Growth and Secondary Metabolism in Fully Expanded Basil Plants.

Indoor production of basil (Ocimum basilicum L.) is influenced by light spectrum, photosynthetic photon flux density (PPFD), and the photoperiod. To investigate the effects of different lighting on growth, chlorophyll content, and secondary metabolism, basil plants were grown from seedlings to fully expanded plants in microcosm devices under different light conditions: (a) white light at 250 and 380 μmol·m-2·s-1 under 16/8 h light/dark and (b) white light at 380 μmol·m-2·s-1 under 16/8 and 24/0 h light/dark. A higher yield was recorded under 380 μmol·m-2·s-1 compared to 250 μmol·m-2·s-1 (fresh and dry biomasses 260.6 ± 11.3 g vs. 144.9 ± 14.6 g and 34.1 ± 2.6 g vs. 13.2 ± 1.4 g, respectively), but not under longer photoperiods. No differences in plant height and chlorophyll content index were recorded, regardless of the PPFD level and photoperiod length. Almost the same volatile organic compounds (VOCs) were detected under the different lighting treatments, belonging to terpenes, aldehydes, alcohols, esters, and ketones. Linalool, eucalyptol, and eugenol were the main VOCs regardless of the lighting conditions. The multivariate data analysis showed a sharp separation of non-volatile metabolites in apical and middle leaves, but this was not related to different PPFD levels. Higher levels of sesquiterpenes and monoterpenes were detected in plants grown under 250 μmol·m-2·s-1 and 380 μmol·m-2·s-1, respectively. A low separation of non-volatile metabolites based on the photoperiod length and VOC overexpression under longer photoperiods were also highlighted.

First Report of Pantoea ananatis causing leaf streak disease on wheat (Triticum aestivum) in the United States of America.

Wheat (Triticum aestivum) loses 21.5% yield to pests and diseases annually (Savary et al. 2019). Among the wheat diseases, bacterial leaf streak (BLS) is a growing problem, costing $78.5 million in losses (https://cropprotectionnetwork.org/). In July 2022, we sampled winter wheat leaf samples at Volga (44.30, -96.92), South Dakota, USA with an estimated disease incidence of 40% (n=100). The typical symptoms were water-soaking with large necrotic and chlorotic streaks extending the length of the leaves and were strikingly similar to BLS. To isolate the pathogen, leaves were cut lengthwise into 1 cm pieces and surface-sterilized using a 10% NaOCl solution for 3 min, followed by 70% ethanol for 3 min, and then rinsed with sterile distilled water and placed in 500 ul of sterile distilled water for 5 min and using a sterile loop the water was streaked over a plate of Nutrient Agar (NA). Following Duveiller et al. (1997), the streaked plate was incubated in the dark at 28℃ for 48 h. Observed single colonies were sub-cultured thrice onto fresh NA plates to obtain a pure culture. We named the culture SD101. Bacteria were found to be gram-negative with a colony morphology initially raised, smooth, and white that later turned yellow. DNA was extracted using the Wizard HMW DNA Extraction Kit (Promega, Madison, WI) following the manufacturer's protocol, and sequenced using Nanopore MinION R9.4 (Oxford Nanopore Technology). We used the Rapid Annotation Using Subsystems Technology approach (Aziz eal. 2008) to extract the 16S rDNA, DNA gyrase subunit B (gyrB), and translation initiation factor IF-2 (infB) gene sequences that were deposited in GenBank under accession numbers PP329908.1 for 16S rDNA, PP496481 for infB, and PP328920.1 for gyrB. Homology analysis using CLC Genomics Workbench 22.0.2 (QIAGEN) and BLASTn against the GenBank nucleotide database resulted in a 99.74% match (1543/ 1547 bp) of the 16S sequence, 99.59% match (2674/ 2685 bp) of the infB sequence, and 99.42% match (2396/ 2410 bp) of the gyrB sequence with Pantoea ananatis strain AJ13355 (AP012032). To test pathogenicity, seeds of spring wheat breeding line SD4892 were planted in 30 cm × 30 cm pots in a greenhouse under a 16 h light photoperiod. The inoculum was prepared from 48-h-old NA plates of SD101 rinsed with 1X Phosphate Buffer Saline (PBS buffer), adjusted to an OD600 = 1.0, and amended with two drops of Tween 20 (polyoxyethylene sorbitol ester, Millipore Sigma). PBS with Tween 20 was used as a negative control. The inoculum was sprayed on 15 replicates of 15-day-old seedlings, kept at 95% relative humidity for 48 h, then moved to the greenhouse at 23 to 25°C. The symptoms appeared as water soaking that later turned to necrotic streaks with surrounding chlorosis on all 15 inoculated plants while control plants remained healthy. The pathogen was re-isolated from the leaves as described above. The 16S rDNA, infB, and gyrB sequences amplified and sequenced were identical to the gene sequences from the whole genome sequencing. The experiment was repeated with the same results, completing Koch's postulates. Although P. ananatis is pathogenic on corn, rice, and other plant species in the United States (Coutinho et al. 2009), and was reported pathogenic on wheat in Poland (Krawczyk et al. 2020), this is the first report of its pathogenicity on wheat in the United States. The prevalence, and incidence of BLS disease caused by P. ananatis in wheat is needed to estimate its threat to wheat production and to develop management strategies.

Research Note: Effects of different light-emitting diode lights during egg incubation on hatching performance and embryo development in White King pigeons

The light provide during incubation can influence hatching characteristics (hatching time, hatchability, etc.) and embryo development in chickens, geese, and turkeys. However, relevant studies on this factor in pigeons are lacking. This study investigated the effects of in ovo photostimulation during embryogenesis on hatching performance, squab quality, and embryo development in pigeons. 400 eggs from paired- bred pigeons were randomly distributed into 4 incubation lighting treatments, with 2 replicates per treatment. The treatments included dark as a control (NL), 12-h light, and 12-h dark photoperiods of white light (WL), red light (RL), and green light (GL) (100 lx at egg level) during the first 15 d of incubation. A total of 1,600 eggs in 4 batches from White King pigeons were used. The results showed that hatching time of the WL group was significantly shorter than that of the dark light group (P < 0.05). The hatchability of fertile eggs in the WL group was significantly higher (P < 0.05), whereas the hatchability of fertile eggs in the RL group was significantly lower (P < 0.05) than that of in the control group. Light stimulation had no effect on time to 90% hatching or average hatching time (P > 0.05). In addition, the hatch window was not extended by light stimulation (P > 0.05). The group incubated under GL showed an increase in embryo weight and relative leg muscle on embryonic d 14 and the hatching day compared to the dark incubation (P < 0.05). Green light stimulated the heart and liver development during the early and middle stages of embryogenesis. It was concluded that white light stimulation during embryogenesis accelerated the hatching process, whereas monochromatic green light had a positive effect on embryo development. Our findings provide important guidance for developing light protocols for pigeon egg incubation.

Efficacy and Optimal Timing of Warm-white or Red + Far-red LED Lamps in Regulation of Flowering in Long-day Ornamentals

When natural days are short, photoperiodic lighting at the end or beginning of the day (day extension) or in the middle of the night (night break) promotes flowering of long-day plants. The objective of this study was to compare broad-spectrum warm-white light-emitting diodes (LEDs) and red (R) + far-red (FR) LEDs at flowering regulation when delivered at different timings in the night period. We performed a greenhouse experiment on four long-day ornamentals [coreopsis (Coreopsis grandiflora) ‘Early Sunrise’, snapdragon (Antirrhinum majus) ‘Liberty Classic Yellow’, petunia (Petunia ×hybrida) ‘Easy Wave Burgundy Star’, and petunia ‘Wave Purple Improved’]. We grew plants under a truncated 8-hour photoperiod with or without low-intensity (∼2 μmol·m−2·s−1) nighttime lighting from warm-white or R+FR LEDs. For each light quality, we delivered four timings: 1) 8 hours after dusk; 2) 8 hours before dawn; 3) 4 hours after dusk + 4 hours before dawn; and 4) 4-hour night break. The effectiveness of floral promotion was determined by time from the treatment onset to the first open flower. Coreopsis flowered similarly under all lighting treatments, irrespective of light quality and timing, but did not flower under the short-day treatment by the end of the experiment. At flowering, coreopsis was 18% to 19% shorter under white than R+FR LEDs. In contrast, snapdragon flowered 9 to 20 days later under white than R+FR LEDs, when delivered for 8 hours at night, but flowered similarly under these two lamp types as a 4-hour night break. Compared with the short-day treatment, white and R+FR LEDs promoted flowering of both petunia cultivars, although flowering generally occurred later under white than R+FR LEDs. Snapdragon and petunia ‘Easy Wave Burgundy Star’ developed 30% to 122% more lateral branches under white than R+FR LEDs, when delivered for 8 hours at night. The effectiveness of warm-white LEDs was generally unaffected by timing, although it was most promotive of flowering in snapdragon when delivered for 8 hours before dawn. For R+FR LEDs, 8-hour day-extension lighting was generally more effective than 4-hour night-break lighting, irrespective of timing. We conclude when delivered for 8 hours at night, warm-white LEDs are generally less effective than R+FR LEDs at promoting flowering of long-day ornamentals but similarly effective as 4-hour night-break lighting. The effectiveness of day-extension lighting is generally independent of timing, although for R+FR LEDs, 8 hours after-dusk and/or before-dawn lighting was generally more effective than 4-hour night-break lighting.

Photoperiod-Dependent Effects on Blood Biochemical Markers of Phenolic-Enriched Fruit Extracts.

Fruits are rich in bioactive compounds, such as (poly)phenols, and their intake is associated with health benefits, although recent animal studies have suggested that the photoperiod of consumption influences their properties. Fruit loss and waste are critical issues that can be reduced by obtaining functional fruit extracts. Therefore, the aim of this study was to obtain phenolic-enriched extracts from eight seasonal fruits that can modulate blood biochemical parameters and to investigate whether their effects depend on the photoperiod of consumption. Eight ethanol-based extracts were obtained and characterized, and their effects were studied in F344 rats exposed to short (6 h light, L6) and long (18 h light) photoperiods. Cherry and apricot extracts decreased blood triacylglyceride levels only when consumed under the L6 photoperiod. Pomegranate, grape, and orange extracts reduced cholesterol and fasting glucose levels during the L6 photoperiod; however, plum extract reduced fasting glucose levels only during the L18 photoperiod. The results showed the importance of photoperiod consumption in the effectiveness of phenolic-enriched fruit extracts and promising evidence regarding the use of some of the developed fruit extracts as potential functional ingredients for the management of several blood biomarkers.

Optimal growth conditions to enhance Chlorella vulgaris biomass production in indoor phyto tank and quality assessment of feed and culture stock

Commercial microalgae cultivation is a dynamic field with ongoing efforts to improve efficiency, reduce costs, and explore new applications. We conducted a study to examine how different light exposure periods affect Chlorella vulgaris's growth. We employed a Phyto tank batch system of approximately 3.5 L with LED light control, controlled airflow, and sterilized bags, maintained at 22.0 ± 2.0 °C indoors. Various methods, including spectrophotometry, and cell counter were employed to monitor Chlorella vulgaris growth under different light exposure cycles. Additionally, quality analysis as feed source was employed by proximate, amino acid, beta-glucan, and microbial content analysis. The results revealed significant variations in C. vulgaris biomass production based on light exposure duration. Notably, the 16:8-h light-dark photoperiod exhibited the highest biomass concentration, reaching 6.48 × 107 ± 0.50 cells/mL with an optical density (OD) of 1.165 absorbance at 682 nm. The 12:12-h light-dark photoperiod produced the second-highest biomass concentration, with 2.305 × 106 ± 0.60 cells/mL at an OD of 0.489. Proximate analysis of dry algae powder revealed low lipid content (0.48 %), high protein content (37.61 %), variable ash concentration (average 10.75 %), and a significant carbohydrate fraction (51.16 %) during extended daylight and shorter dark periods. Amino acid analysis identified nine essential amino acids, with glutamic acid being the most abundant (17.7 %) and methionine the least (0.4 %). Furthermore, quality analysis and microbiological assays demonstrated that the C. vulgaris biomass is well-suited for fish and livestock use as a feed source and possibility as human nutraceuticals. These findings can be considered more environmentally friendly and ethically sound due to the absence of genetic modification.

Long-term substitution of fish oil with alternative sources in Atlantic salmon (Salmo salar): Performance, health, and consumer appeal

Salmon farming in Chile faces the dual challenge of maintaining growth while improving sustainability. One approach to advance sustainability involves the feeds without marine-fishery inputs. This study aimed to evaluate the effect of completely replacing fish oil (FO) on the performance of Salmo salar throghout marine grow-out. The investigation involved fish ranging from 400 g to 4000 g and explored three diets without fish meal, each which included 2.2% EPA + DHA from different sources: FO (control), transgenic canola oil (Can n-3) and Schizochytrium sp. oil (AOV) as unique type of oils. Each diet was randomly distributed in triplicate among nine tanks with a recirculation system maintained at 12 °C, with automatic feeding and a 24-h light photoperiod. Fish density was 29 fish m−3 at day 133 of the experiment and seven fish m−3 at day 319. The diets were isoproteic, isolipidic and isoenergetic. Fish were evaluated at 133 and 319 days of experiment in terms of productive performance, liver health, EPA + DHA and lipid retention efficiency, fatty acid metabolism, response to acute stress, and final product quality. The results showed similar productive performance and liver health among the three diets during both sampling periods. No differences were observed in lipid or EPA + DHA retention efficiency in the whole body or fillet. Eicosanoids and receptors for anti-inflammatory mediators derived from EPA and DHA showed similar or higher capacities in fish fed with Can n-3 and AOV than those fed FO. Responses to induced stress, measured through lactate, cortisol, sodium, potassium, chloride, glucose, and the liver profile were similar between the three diets. Similarly in fillet quality between the three diets. However, sensory analysis revealed a lower intensity of “global aroma” in Can n-3-fed fish fillets and lower evaluations in “typical salmon aroma”, “oily aroma” and “fresh flavor” in AOV-fed fish fillets when they are compared with FO. The nutritional indicators of the final product were similar between the three diets, except for PUFA/SFA, the thrombogenicity index, hypercholesterolemia/hypocholesterolemia, and the health promotion index. In these specific indicators, fish fed with Can n-3 and AOV demonstrated more favorable results for consumer health than the FO-fed fish.

Integrated transcriptome and metabolome analysis reveals anthocyanin biosynthesis mechanisms in pepper (Capsicum annuum L.) leaves under continuous blue light irradiation

BackgroundDifferent metabolic compounds give pepper leaves and fruits their diverse colors. Anthocyanin accumulation is the main cause of the purple color of pepper leaves. The light environment is a critical factor affecting anthocyanin biosynthesis. It is essential that we understand how to use light to regulate anthocyanin biosynthesis in plants.ResultPepper leaves were significantly blue–purple only in continuous blue light or white light (with a blue light component) irradiation treatments, and the anthocyanin content of pepper leaves increased significantly after continuous blue light irradiation. This green-to-purple phenotype change in pepper leaves was due to the expression of different genes. We found that the anthocyanin synthesis precursor-related genes PAL and 4CL, as well as the structural genes F3H, DFR, ANS, BZ1, and F3’5’H in the anthocyanin synthesis pathway, had high expression under continuous blue light irradiation. Similarly, the expression of transcription factors MYB1R1-like, MYB48, MYB4-like isoform X1, bHLH143-like, and bHLH92-like isoform X3, and circadian rhythm-related genes LHY and COP1, were significantly increased after continuous blue light irradiation. A correlation network analysis revealed that these transcription factors and circadian rhythm-related genes were positively correlated with structural genes in the anthocyanin synthesis pathway. Metabolomic analysis showed that delphinidin-3-O-glucoside and delphinidin-3-O-rutinoside were significantly higher under continuous blue light irradiation relative to other light treatments. We selected 12 genes involved in anthocyanin synthesis in pepper leaves for qRT-PCR analysis, and the accuracy of the RNA-seq results was confirmed.ConclusionsIn this study, we found that blue light and 24-hour irradiation together induced the expression of key genes and the accumulation of metabolites in the anthocyanin synthesis pathway, thus promoting anthocyanin biosynthesis in pepper leaves. These results provide a basis for future study of the mechanisms of light quality and photoperiod in anthocyanin synthesis and metabolism, and our study may serve as a valuable reference for screening light ratios that regulate anthocyanin biosynthesis in plants.

Effect of light intensity and photoperiod on high-value production and nutrient removal performance with bacterial-algal coupling system

Direct discharge of mariculture wastewater can lead to eutrophication, posing a threat to aquatic ecosystems. A novel Bacteria-Algae Coupled Reactor (BACR) offers advantages in treating mariculture wastewater, which can effectively remove pollutants while simultaneously obtaining microalgal products. However, there is limited information available on how illumination affects the cultivation of mixotrophic microalgae in this bacteria-algae coupling system. Therefore, a combined strategy of photoperiod and light intensity regulation was employed to improve the biological mariculture wastewater remediation, promote microalgae biomass accumulation, and increase the high-value product yield in this study. Optimal light conditions could effectively enhance microalgal carbohydrate, protein, lipid accumulation and photosynthetic activity, with the carbohydrate, protein and lipid contents reached 44.11, 428.57 and 399.68 mg/L, respectively. Moreover, excellent removal rates were achieved for SCOD, NH4+-N and TP, reaching 86.68%, 87.35% and 95.13% respectively. This study proposes a comprehension of BACR processes in mariculture wastewater under different light conditions.