Effect Of Light Regimes Research Articles

Effects of light regimes on circadian gene co‐expression networks in Arabidopsis thaliana

AbstractLight/dark (LD) cycles are responsible for oscillations in gene expression, which modulate several aspects of plant physiology. Those oscillations can persist under constant conditions due to regulation by the circadian oscillator. The response of the transcriptome to light regimes is dynamic and allows plants to adapt rapidly to changing environmental conditions. We compared the transcriptome of Arabidopsis under LD and constant light (LL) for 3 days and identified different gene co‐expression networks in the two light regimes. Our studies yielded unforeseen insights into circadian regulation. Intuitively, we anticipated that gene clusters regulated by the circadian oscillator would display oscillations under LD cycles. However, we found transcripts encoding components of the flavonoid metabolism pathway that were rhythmic in LL but not in LD. We also discovered that the expressions of many stress‐related genes were significantly increased during the dark period in LD relative to the subjective night in LL, whereas the expression of these genes in the light period was similar. The nocturnal pattern of these stress‐related gene expressions suggested a form of “skotoprotection.” The transcriptomics data were made available in a web application named Cyclath, which we believe will be a useful tool to contribute to a better understanding of the impact of light regimes on plants.

Effects of weaning time, light regime, and stocking density on growth, condition, survival, and cannibalism rates in northern pike (Esox lucius L.) larvae and early juveniles under intensive culture

In this study, three separate experiments were conducted to optimize the intensive larviculture of pike (Esox lucius L.) under different weaning times, light regimes, and stocking densities. In the first experiment, larvae were fed sequential combinations of live feed (LF), co-feeding with dry starter (DS), and only DS feed for 18 days as follows: 9 days LF followed by 3 days co-feeding and 5 days DS (group A); 6 days LF followed by 3 days co-feeding and 9 days DS (group B); 3 days LF followed by 3 days co-feeding and 12 days DS (group C); and DS alone for 18 days (group D). Fish fed LF had significantly higher growth rates than those fed a dry diet (p< 0.05). Extending the feeding period on LF resulted in a significantly higher growth rate (24.6% d−1), variability (13.5%), and heterogeneity (299.5% d−1) than fish fed a DS. In the second experiment, the effect of the light regime was assessed at eight different levels (L0:D24; L24:D0; L16:D8; L4:D4:L4:D4:L4:D4; L8:D4:L8:D4; L12:D12; L8:D16; and L4:D8:L4:D8). The growth and survival of the larvae increased with increasing light period. Groups exposed to complete light (L24:D0) and 16 h of light (L16:D8) exhibited significantly higher weight gain and specific growth rate (SGR, %) than the other groups. The highest survival was observed in fish reared with complete light (68.5 ± 4.5%) and an L8:D4:L8:D4 light regime (61.4 ± 5.2%). All larvae maintained under L0:D24 died during the experiment. The third experiment tested the effect of the fish density within four experimental groups: 10 ind L−1, 20 ind L−1, 40 ind L−1, and 80 ind L−1. Fish at densities of 20 and 40 ind L−1 had significantly higher weight gain and SGR (%) than those in the other groups. The highest survival was in fish reared with 20 ind L−1 density (72.5 ± 8.5%). Fish at densities of 10 and 80 ind L−1 showed significantly higher cannibalism rates than those in the other groups. These results indicated that weaning time, photoperiod, and stocking density play significant roles in early pike larval performance.

Effects of light regimes and benthic fish disturbance on the foraging behavior of Vallisneria natans in heterogeneous sediments.

In shallow eutrophic lakes, submersed macrophytes are significantly influenced by two main factors: light availability and benthic fish disturbance. Plant foraging is one of the most crucial aspects of plant behavior. The present study was carried out to effects of light regimes and fish disturbance on the foraging behavior of Vallisneria natans in heterogeneous sediments. V. natans was cultivated in heterogeneous sediments with four treatments: high-light regime (H), high-light regime with benthic fish (HF), low-light regime (L), and low-light regime with benthic fish (LF). We use plant trait network analysis to evaluate the relationships between traits in heterogeneous sediments. We found the plant foraging intensity was positively correlated with trait network modularity. The biomass of stem, maternal plant biomass ratio, and ramet number were the hub traits of plant growing in heterogeneous habitats. Although the plant relative growth rate (RGR) was positively correlated with foraging intensity, the hub traits had closer links with plant RGR than foraging intensity. Light regime and benthic fish indirectly affected the plant foraging intensity by changing the chlorophyll a content and pH of overlying water. Overall, our analysis provides valuable insights into plant foraging behavior in response to environmental changes.

Studies on Aspergillus flavus on Tiger Nut (Cyperus esculentus) Incubated at Different Regimes of Light and Two Temperatures

An experiment was carried out to ascertain the effect of light regimes (continuous day light, continuous darkness and alternating day light and darkness) on the growth of A. flavus on tiger nut at temperature of 28oC and 30oC. The experiment was a 2 x 3 factorial laid out in a completely randomized design (CRD) replicated 10 times. A. flavus was isolated from naturally infected tiger nuts obtained from different sellers at Delta Park, Abuja Park and Choba campus, University of Port Harcourt, Rivers State, Nigeria. The isolation and sub-culturing were done using Malt Extract Agar (MEA). A tiger nut-based-medium (15ml/Plate) was centrally inoculated with 6-day-old inoculums of A. flavus and incubated appropriately. Assessment of fungal growth was done daily for 10 days and mycelia diameter and mycelia growth rate obtained from the data. Result from the statistical analysis showed that the effect of light regime and temperature on the mycelia diameter of A. flavus was highly significant (P<0.001) and the interaction between light regime and temperature was also significant (P<0.0.01). Growth rate also showed significant (P<0.001) main effect of temperature and light regime and the light regimes x temperature was also significant (P=0.03). The highest mycelia growth rate and mycelia diameter occurred in continuous day light, followed by continuous darkness and finally alternating day light and darkness, with all higher at 30oC. Thus, storage of tiger nut under continuous day light and/or at temperature 28oC and above should be discouraged, in order to reduce microbial spoilage caused by Aspergillus flavus.

The effects of light regime on carbon cycling, nutrient removal, biomass yield, and polyhydroxybutyrate (PHB) production by a constructed photosynthetic consortium

Microalgae can add value to biological wastewater treatment processes by capturing carbon and nutrients and producing valuable biomass. Harvesting small cells from liquid media is a challenge easily addressed with biofilm cultivation. Three experimental photobioreactors were constructed from inexpensive materials (e.g. plexiglass, silicone) for hybrid liquid/biofilm cultivation of a microalgal-bacterial consortia in aquaculture effluent. Three light regimes (full-spectrum, blue-white, and red) were implemented to test light spectra as a process control. High-intensity full-spectrum light caused photoinhibition and low biomass yield, but produced the most polyhydroxybutyrate (PHB) (0.14 mg g−1); a renewable bioplastic polymer. Medium-intensity blue-white light was less effective for carbon capture, but removed up to 82 % of phosphorus. Low-intensity red light was the only net carbon-negative regime, but increased phosphorus (+4.98 mg/L) in the culture medium. Light spectra and intensity have potential as easily-implemented process controls for targeted wastewater treatment, biomass production, and PHB synthesis using photosynthetic consortia.

The effect of light regime and time of slaughter in broiler on broiler performance, liver antioxidant status, and expression of genes related to peptide absorption in the jejunum and melatonin synthesis in the brain.

This study aimed to assess the effects of light regime and time of slaughter on primal cut and organ weights, peptide transporter 1 (PEPT1) gene expression in the jejunum, arylalkylamine N-acetyltransferase (AANAT) gene expression in the brain, and liver oxidant/antioxidant status in broilers aged 37 days. The experiment was conducted in a factorial completely randomized design, with two light regimes (intermittent light varying according to bird age and continuous light under an 18 h light/6 h dark photoperiod) and four times of slaughter (2:00, 8:00, 14:00 and 20:00 h). There was an interaction effect on PEPT1 and AANAT expression, lipid and protein oxidation and superoxide dismutase (SOD) activity. In both light regimes, PEPT1 expression responded cubically to slaughter time. In the continuous light group, PEPT1 expression was highest in birds slaughtered at 2:00 and 14:00 h, whereas, in the intermittent light treatment, expression was highest at 8:00 h. In the continuous light regime, AANAT expression had a cubic relationship with time of slaughter, with the greatest values recorded at 20:00 h. In the intermittent light regime, slaughter time showed a cubic effect on lipid oxidation, which was highest at 8:00 h. In the continuous light group, there was a cubic effect on nitrite concentration, lipid oxidation, protein oxidation, and SOD activity; nitrite levels, lipid oxidation, and protein oxidation were highest and SOD activity was lowest in birds slaughtered at 14:00 h. Time of slaughter influenced catalase activity, which responded cubically; catalase activity was lowest at 8:00 and 14:00 h. This study is the first to demonstrate that PEPT1 expression in the jejunum of broilers follows a diurnal rhythm and varies according to light regime. The results also suggest that mainly continuous lighting and slaughter at 14:00 h when the animals are possibly more active may be more stressful to broilers.

Effects of light regime on circadian rhythmic behavior and reproductive parameters in native laying hens

The paper aimed to study the effects of light regime on circadian rhythmic behavior and reproductive parameters in a native laying hen, Beijing You Chicken (BYC) during 22 to 30 wk. A total of 630 19-wk-old BYC female chicken were allocated to 6 light regime groups with 3 replicates per group and 35 birds per replicate, reared in individually lit floor pens with separate outdoor areas. A 2 × 3 factorial experiment (2 lighting patterns: continuous and intermittent lighting; 3 photoperiods: 16 h, 14 h, 12 h) was arranged, including 16L:8D for group 1; 12L:2D:4L:6D for group 2; 14L:10D for group 3; 10L:2D:4L:8D for group 4; 12L:12D for group 5, and 8L:4D:4L:8D for group 6, respectively. The circadian rhythmic behavior of the hens, including feeding, egg-laying and sleeping behaviors were observed by scan sampling and target sampling method for consecutive 3 d every other week during 22 to 30 wk. Infrared cameras were set outside each pen to record the rhythmic behaviors of the birds every other hour (6:00–7:00;8:00–9:00;10:00–11:00;12:00–13:00;14:00–15:00;16:00–17:00;18:00–19:00;20:00–21:00;22:00–23:00;0:00–1:00;2:00–3:00;4:00–5:00). Theovarian weight, oviduct weight, oviduct length, the number of large yellow follicles (LYF), and small yellow follicles (SYF) were measured at the end of 30 wk. The egg-laying rate during 22 to 30 wk was measured. The results showed that the highest feeding frequency was given by the 16L:8D, and the lowest given by the 12L:12D (P < 0.05). The average feeding duration was the longest in the 8L:4D:4L:8D at 6:00 to 8:00 (18.67 min/hen) (P < 0.05), and the shortest in the 8L:4D:4L:8D at 18:00 to 20:00 (3.75 min/hen) (P < 0.05). The highest egg-laying frequency was given by the 8L:4D:4L:8D (0.28), the lowest given by the 10L:2D:4L:8D (0.21) (P < 0.05). The shortest egg-laying duration occurred at 6:00 to 8:00, was given by the 16L:8D (8 min/hen), and the longest egg-laying duration occurred at 18:00 to 20:00, was given by 16L:8D and 8L:4D:4L:8D (>20.5 min/hen) (P < 0.05). The highest sleeping frequency was given by the 12L:2D:4L:6D, the lowest was given by the 12L:12D (P < 0.05). At 6:00 to 8:00, the shortest sleeping duration was given by 12L:2D:4L:6D (1.5 s/hen), at 18:00 to 20:00, the longest given by 8L:4D:4L:8D (14.3 s/hen) (P < 0.05). Lighting pattern and photoperiod alone or in interaction had no effect on egg-laying rate during 22 to 30 wk (P > 0.05), but had significant effects on ovarian weight, oviduct weight, oviduct length, the number of LYF and SYF (P < 0.05), and the continuous groups were all significantly higher than the intermittent groups (P < 0.05). The present study indicated that light regimes affected the frequency and duration of circadian behavior in BYC laying hens, and the continuous light was more beneficial to the reproductive development than the intermittent light in the early laying period.

Effects of light regime on the hatching performance, body development and serum biochemical indexes in Beijing You Chicken

The paper aimed to study the effects of light regime during the incubation on hatching performance, body development and serum biochemical indexes in Beijing You Chicken (BYC). A total of 1,408 BYC eggs were randomly allocated into 4 groups: 24 h dark as the control (Inc24D); 3 light regimes were 8 h light and 16 h dark group (Inc8L:16D); 12 h light and 12 h dark group (Inc12L:12D); 16 h light and 8 h dark group (Inc16L:8D), respectively. There were 352 eggs in each group, 4 replicates each group and 1 tray each replicate, 88 eggs each tray. Light-emitting diode (LED) strips, white light with temperature of 4,500 to 5,000 K, 150 to 200 lx were set up. The results showed that light regimes had no significant effects on hatching rate of eggs, hatching rate of fertile eggs and healthy rate of chicks (P > 0.05), but the hatching rate of eggs was the lowest in the Inc24D group (87.22%), and the highest in the Inc12L:12D group (93.64%); Lighted incubation significantly affected the incidence of leg problems of 1-day-old chicks (P < 0.05). The incidence rate of leg problems was the highest in the Inc24D group (4.21%), and was decreased in Inc12L:12D and Inc16L:8D groups (P < 0.05). Femur length in the Inc12L:12D group was greater than that in the Inc24D and Inc16L:8D groups (P = 0.011), but there were no differences between Inc8L:16D group and other three groups (P > 0.05). The relative brain weight of 1-day-old chicks was higher in Inc24D and Inc16L:8D groups than in Inc8L:16D group (P = 0.052), but had no difference with Inc12L:12D group. Light regimes during incubation had no effects on serum total protein, albumen, globulin, and urea nitrogen content of 1-day-old chicks (P > 0.05), while the globulin content in Inc12L:12D group was numerically greater than in other three groups (P = 0.063). Lysozyme content in Inc12L:12D group was higher than that in the Inc24D and Inc8L:16D groups (P < 0.05), but had no difference with that in Inc16L:8D group. Light regime had no effect on serum total antioxidant capability (T-AOC) (P > 0.05), but significantly affected the activities of glutathione peroxidase (GSH-Px) and total superoxide dismutase (T-SOD) (P < 0.05). The GSH-Px and T-SOD activities in the Inc12L:12D group were higher than those in the Inc24D and Inc8L:16D groups. The MDA content of Inc24D was the highest (9.67 nmol/mL) compared to the others, which was very close to the significant level (P = 0.056). In conclusion, 12 h light and 12 h dark incubation has the potential to improve the hatching performance of BYC eggs, benefit for the long bone development, improve some serum immune and antioxidant indexes, and reduce the leg problems in 1-day-old chicks.

Effects of different light regimes on Dunaliella salina growth and β-carotene accumulation

Outdoor cultivations of microalgae for commercial scale production usually rely on natural sunlight following ‘Sine’ regime, but most lab scale studies adopt ‘Block’ or ‘Continuous’ regimes, leading to poor prediction of outdoor cultivation results. To fill this gap on β-carotene production by Dunaliella salina, the effects of light regimes (‘Block’, ‘Sine’, ‘Continuous’) on cell growth and β-carotene accumulation in D. salina were investigated in this study. The results showed significant difference between these regimes. When receiving the same amount of illumination, ‘Sine’ mode inferred 10–55% higher biomass yield and 31–58% higher β-carotene yield than those under the ‘Block’ mode. The biomass concentration, as well as protein and total fatty acid (TFA) content, has no significant difference between different light regimes, but the starch content in the ‘Continuous’ light regime was higher than that of ‘Sine’ and ‘Block’ regime. β-carotene accumulation under ‘Continuous in summer’ and ‘Simulated diurnal irradiance in summer’ regimes were correlated with increase (C18:1, C18:2) and decrease (C16:4, C18:3) of specific fatty acids (FAs) contents, rather than TFA content. Meanwhile, it was found that β-carotene accumulation was correlated with periodical Fv/Fm fluctuations under different light regimes, and indicate that exposure to periodical strong light is more favorable for β-carotene accumulation, rather than continuous light. These results indicated the significance of using ‘Sine’ light regime since it not only provided better predictions on outdoor production, but also helpful for increase biomass and β-carotene productivities.

The Response of Egyptian Spinach and Vegetable Amaranth Microgreens to Different Light Regimes

Production of specialty microgreens under controlled environments can help increase their supply in Texas. This experiment was carried out to evaluate the effects of light regimes on the growth of Egyptian spinach and vegetable amaranth microgreens in a grow tent.

Effects of solar radiation on regeneration patterns in a Nothofagus dombeyi (Mirb.) Oerst. old-growth forest in Chile&amp;#8217;s central-southern Andes

Nothofagus species behave like early successional species that recolonize open sites after of regular and large-scale disturbances. This study analyzed the effects of light regimes on patterns of advanced regeneration dynamics, growth in diameter and height of Nothofagus dombeyi (Mirb.) Oerst. (Density of 240 trees ha-1, basal area of 56.7 m2 ha-1). Systematic sampling every 50 m in three stands (7.5 ha) was used. At each point and with the same center, two concentric circular plots were established, 9.0 m and 1.8 m radius. For estimate solar radiation transmissivity in plots, a solariscope hemispheric photographic camera was used. Diameters at breast height and basal areas (BA), heights (H) were measured and then counted and measured N. dombeyi seedlings and saplings. 13 saplings of advanced regeneration were harvested from all gaps to obtain age (E), total height (TH), absolute radial growth (ARG), and absolute height growth (AHG). As results, solar radiation varied between 3 and 40%. ARG varied between 1.20 and 2.22 mm yr-1 and AHG between 0.15 and 0.43 m yr-1. We found correlation for ARG and AHG with direct and global solar radiation transmissivity, but not with diffuse solar radiation transmissivity. The plant age and transmittance of direct and global solar radiation explains the increases in diameter and height. However, in our study stated that in the Andean region of south-central Chile, N. dombeyi stands is affected by small-scale disturbances. Therefore, transmissivity radiation solar inside the forest, explaining natural regeneration patterns and growth of N. dombeyi.

Removal of metals from water using a novel high-rate algal pond and submerged macrophyte pond treatment reactor.

A combined high-rate algal pond and submerged macrophyte pond (APMP) reactor was introduced as a novel biotechnique for efficient heavy metals (HMs) removal from wastewater. The role of water temperature, light regime, and N:P mass ratio on algae growth and HMs removal as well as effects of macrophyte species and densities on algae extermination were investigated through batch experiments. Results showed that water temperature significantly affected algae proliferation and HMs removal. Effects of light regime and N:P only showed obvious influences on HMs removal performance at high temperature. HMs removal efficiency reached 75.8% (Cr), 63.6% (Pb), and 61.1% (Zn) at 5-day hydraulic retention time (HRT) in APMP. Positive correlation existed closely between HMs removal and algal growth with long HRT. Algae were strongly inhibited by Ceratophyllum demersum and Vallisneria natans at plant density of 20-30 rhizomes m-2 with effluent algae concentration about 1,000 cells mL-1 at 7-day HRT. Results suggested that the APMP reactor was efficient for HMs removal from wastewater, indicating a possible effective metals removal technique by using APMP.

Seed enhancing treatments: comparative analysis of germination characteristics of 23 key herbaceous species used in European restoration programmes.

The response of seeds from 23 wild plant species to a range of seed enhancing treatments was studied. We tested the hypothesis that sensitivity of the 23 species to these compounds is related to their ecological niche. The three ecological niches considered were open land, open-pioneer and woodland. Hence, the germination of a species is likely adapted to different light conditions and other environmental signals related to the niche. As representatives of environmental signals, the effects of smoke-related compounds (karrikinolide, KAR1 ), nitrate and plant growth regulator (gibberellic acid, GA3 ) on germination were studied. Seeds were exposed to these additives in the imbibition medium; all described as germination cues. We also investigated the effect of light regimes and additives on germination parameters, which included final germination, germination rate and uniformity of germination. Seeds were placed to germinate under three light conditions: constant red light, constant darkness and 12h white light photoperiod. We observed inhibition by KAR under light in some species, which may have ecological implications. The results showed that no single treatment increased the germination of all the tested species, rather a wide variation of responsiveness of the different species to the three compounds was found. Additionally, no interaction was found between responsiveness to compounds and ecological niche. However, species in the same ecological niche and dormancy class showed a similar responsiveness to light. Species that share a similar environment have similar light requirements for germination, while differences exist among species in their responsiveness to other germination cues.

Between and within laboratory reliability of mouse behaviour recorded in home-cage and open-field

BackgroundReproducibility of behavioural findings between laboratories is difficult due to behaviour being sensitive to environmental factors and interactions with genetics. The objective of this study was to investigate reproducibility of behavioural data between laboratories using the PhenoTyper home cage observation system and within laboratory reproducibility using different lighting regimes. New methodThe ambulatory activity of C57BL/6 and DBA/2 mice was tested in PhenoTypers in two laboratories under near identical housing and testing conditions (Exp. 1). Additionally activity and anxiety were also assessed in the open-field test. Furthermore, testing in either a normal or inverted light/dark cycle was used to determine effects of lighting regime in a within-laboratory comparison in Aberdeen (Exp. 2). ResultsUsing the PhenoTyper similar circadian rhythms were observed across laboratories. Higher levels of baseline and novelty-induced activity were evident in Aberdeen compared to Utrecht although strain differences were consistent between laboratories. Open field activity was also similar across laboratories whereas strain differences in anxiety were different. Within laboratory analysis of different lighting regimes revealed that behaviour of the mice was sensitive to changes in lighting. Comparison with existing methodsUtilisation of a home cage observation system facilitates the reproducibility of activity but not anxiety-related behaviours across laboratories by eliminating environmental factors known to influence reproducibility in standard behavioural tests. ConclusionsStandardisation of housing/test conditions resulted in reproducibility of home cage and open field activity but not anxiety-related phenotypes across laboratories with some behaviours more sensitive to environmental factors. Environmental factors include lighting and time of day.

Germination responses to water potential in Bromus sterilis L. under different temperatures and light regimes

Barren brome (Bromus sterilis L.) is a troublesome weed of winter cereals in western and central Europe and its control requires an exact estimation of emergence time. The study focused on the germination response of populations from the Czech Republic to water availability at different temperatures and under different light regimes. Seeds were able to germinate even at very low water potential (Ψ) close to the wilting point, but decreasing temperatures below 25°C and exposure to light decreased the germination percentage (GP) and prolonged the time to reach 50% germination (T&lt;sub&gt;50&lt;/sub&gt;). At higher temperatures of 15, 20, and 25°C, seeds germinated up to a Ψ value of–1.5 MPa; however, the GP differed between light (0–3%) and darkness (50–75%). At the highest temperature of 25°C and germination in water, T&lt;sub&gt;50&lt;/sub&gt; was less than 1 day, but a decrease in Ψ to –1.5 MPa prolonged the T&lt;sub&gt;50&lt;/sub&gt; to&lt;br /&gt; 5 days; however, this occurred without any significant effect of light regime. With decreasing temperature and Ψ, seeds were more sensitive to the light regime and the disproportion between T&lt;sub&gt;50&lt;/sub&gt; in light and darkness increased. At a Ψ of less than –1.0 MPa, seeds needed twice as long for germination in light than in darkness when germinating at 20°C or 15°C. The results may be of value for the development of predictive models and for identifying times when weed control may be the most effective.

Diving behaviour of Atlantic salmon at sea: effects of light regimes and temperature stratification

Accepted manuscript version. Published version available in Marine Ecology Progress Series, 2017;574:127-140

Biomass Allocation, Compensatory Growth and Internal C/N Balance ofLolium perennein Response to Defoliation and Light Treatments

ABSTRACT Light environments can have a considerable influence on how plants respond to defoliation through influencing the biomass allocation patterns and internal C/N ratio. Seedlings of Lolium perenne, a common perennial grass species, were grown for eight weeks under three different light environments (natural light, red light and shading) and two different defoliation treatments (no defoliation versus 50% aboveground biomass removal). This study was conducted to examine (1) the effects of light regimes and defoliation on biomass accumulation, biomass allocation and internal C/N ratio status in plants; (2) how the light regimes influence the pattern of compensatory growth after defoliation; and (3) the relationship between compensatory growth and the internal C/N ratio status. We found that red light altered the shoot-to-root allometry, enhanced the leaf C concentrations and induced N deficiency. By contrast, the leaf N concentrations of L. perenne were greater during shading treatment, which simultane...

Effect of light regime and provenance on leaf characteristics, growth and flavonoid accumulation in Cyclocarya paliurus (Batal) Iljinskaja coppices.

BackgroundAs a highly valued and multiple function tree species, Cyclocarya paliurus is planted and managed for timber production and medical use. However, limited information is available on its genotype selection and cultivation for growth and phytochemicals. Responses of growth and secondary metabolites to light regimes and genotypes are useful information to determine suitable habitat conditions for the cultivation of medicinal plants.ResultsBoth light regime and provenance significantly affected the leaf characteristics, leaf flavonoid contents, biomass production and flavonoid accumulation per plant. Leaf thickness, length of palisade cells and chlorophyll a/b decreased significantly under shading conditions, while leaf areas and total chlorophyll content increased obviously. In the full light condition, leaf flavonoid contents showed a bimodal temporal variation pattern with the maximum observed in August and the second peak in October, while shading treatment not only reduced the leaf content of flavonoids but also delayed the peak appearing of the flavonoid contents in the leaves of C. paliurus. Strong correlations were found between leaf thickness, palisade length, monthly light intensity and measured flavonoid contents in the leaves of C. paliurus. Muchuan provenance with full light achieved the highest leaf biomass and flavonoid accumulation per plant.Conclusions Cyclocarya paliurus genotypes show diverse responses to different light regimes in leaf characteristics, biomass production and flavonoid accumulation, highlighting the opportunity for extensive selection in the leaf flavonoid production.

Effects of light regime and substrain on behavioral profiles of male C57BL/6 mice in three tests of unconditioned anxiety

Substrains of the C57BL/6 inbred mouse are widely used in genetic, behavioral and physiological research, as well as models for human disease. Throughout, the choice of the respective substrain can have a large influence on experimental results. Likewise, the conditions under which experiments are performed, such as the light regime, can significantly affect the outcome of an experiment, especially when aiming at experimental behavior. Here, two commonly used mouse substrains, C57BL/6JOlaHsd and C57BL/6NCrl, were housed under either a conventional or a reverse light regime and were tested in either the light phase or the dark phase, respectively. All animals were exposed to three unconditioned anxiety-related behavior set-ups: the modified Hole Board test, the light-dark box and the elevated plus maze. Significant substrain and light regime effects were found in all three behavioral tests, with some of the latter being substrain and test specific. This signifies the importance of the choice of substrain used in for example, a mouse knockout experiment studying behavior, also in relation to light regime under which the animals are tested.

Development of an algal treatment system for Se removal: Effects of light regimes, nutrients, sulfate and hypersalinity

Selenium (Se) exposure poses potential risks to wildlife at the Salton Sea. Our previous research suggests Chlorella sp. be highly efficient at absorbing and volatilizing Se. In developing an algal treatment system for Se removal, this study further evaluated the performance under the conditions to be encountered in the field using Chlorella pyrenoidosa and Chlorella vulgaris. The results show the algal Se removal efficiency was little affected by photoperiod, yet volatilization became relatively greater in dark/light cycles over a longer term. The rates of Se absorption and volatilization by C. vulgaris were 88% and 77% more, respectively, in the DI water, while C. pyrenoidosa acted oppositely, indicating C. vulgaris will perform better in Se removal if nutrient levels are reduced in advance. The presence of sulfate reduced biomass Se, especially through volatilization, by 8% for C. vulgaris, lessening potential ecotoxicity. Finally, C. vulgaris released biomass Se back to the water column under hypersaline conditions, leading to a 6% increase in water Se concentrations. These results suggest C. vulgaris be the best alga for the treatment of Se laden river water in the Salton Sea area, yet a filtering system is required to prevent Se containing algae from entering food chains.