Effect Of Light Regimes Research Articles

Substrain and light regime effects on integrated anxiety-related behavioral z-scores in male C57BL/6 mice—Hypomagnesaemia has only a small effect on avoidance behavior

Magnesium (Mg) has been described to possess an anxiolytic function, but a number of studies present inconsistent results on this matter. In this study the effect of Mg deficiency on anxiety-related behavior, brain and blood plasma Mg in young adult male C57BL/6JOlaHsd and C57BL/6NCrl mice was studied. The animals were put on a control or Mg deficient diet from day 0 and significant hypomagnesaemia was evident from day 12 onwards in the test animals. Housing and test conditions were under either conventional light regime (white light behavioral test conditions) or reverse light regime (red light behavioral test conditions). The animals were tested in three tests for unconditioned anxiety: the modified Hole Board (day 14), the light-dark test (day 21) and the elevated plus maze (day 28). Overall integrated behavioral z-scores were calculated over these three behavioral tests. Mg showed a structure dependent distribution at the level of the brain, that differed between C57BL/6 substrain and light regime (conventional versus reverse), respectively. Likewise, total brain Mg did differ between substrain and light regime, but was not affected by the diet. Animals on the Mg deficient diet housed under conventional light regime had a higher final (day 28) blood plasma corticosterone level as compared to controls. Animals housed under reverse light regime exhibited no diet effect of plasma corticosterone levels. The significant hypomagnesaemia at blood plasma level resulted in an effect of Mg deficiency on avoidance, but not overall anxiety-related behavior. Significant differences regarding avoidance behavior were found between the two substrains and light regimes, respectively.

Regimes de luz na produção de conídios de Trichoderma harzianum para controle do mofo branco em feijoeiro

RESUMO O mofo branco tem sido responsável por danos expressivos à cultura do feijoeiro. Objetivou-se avaliar o efeito de regimes de luz na produção de conídios de Trichoderma harzianum e na efetividade destes em inibir a germinação miceliogênica de escleródios de Sclerotinia sclerotiorum, bem como de isolados de T. harzianum na supressão de lesões causadas por S. sclerotiorum sobre folíolos de feijoeiro. O isolado CEN287 inibiu a germinação miceliogênica de 80 % dos escleródios avaliados. Tal efetividade não se alterou quanto ao regime de luz empregado para a obtenção dos conídios de T. harzianum. Os isolados CEN287, CEN288 e CEN316 proporcionaram os menores valores médios de lesão foliar aos 10 dias após a inoculação, sendo de 4,25 mm2; 2,97 mm2; e 2,98 mm2, respectivamente. Em relação à testemunha, tais valores foram significativamente inferiores (72,90 mm2), o que impediu a rápida deterioração do tecido vegetal.

Effect of different light regimes on fitness of two species of Drosophila montium subgroup

Most organisms possess “biological chronometers” in the form of circadian clocks. Organism possessing circadian clock gains fitness advantage in two ways, by synchronizing its behavior through physiological process and secondly by coordinating its internal metabolic process. Environmental manipulations of circadian clocks have been shown to affect many life-history-related traits. Life-history traits are important components of fitness. To enhance individual fitness, organism has to synchronize the physiology with the surrounding environment. The present investigations were made to understand whether rhythm changes affect fitness of two co-existing species of montium a subgroup of Drosophila. The stocks were maintained at 20 ± 1 °C with 75% RH. Fitness such as fecundity, male lifetime fertility, female lifetime fertility, and longevity was assessed in LD (light/dark), LL (continuous light), and DD (continuous dark) for 15 and 30th generations. Fecundity was assessed in 25 pairs of flies for 20 days, and fertility and longevity was assessed in 10 pairs of flies until lifetime. The result revealed differential effect of light regimes on the two different species of Drosophila. Although the two species are related, effect of the three light regimes, LD, LL, and DD on them was different. It is evident that these two species although genetically related exhibit different responses to different light regimes.

Effects of light regime on larvae survival, growth and settling behavior of hatchery reared American lobster (Homarus americanus)

Abstract Throughout the world, several efforts currently exist for restocking clawed lobster ( Homarus sp.) by releasing mass amounts of postlarvae in the wild. Therefore, optimization of hatchery techniques and evaluation of their influence on lobster postlarvae behavior at release time are of interest. This study looked at the effects of light regime (photoperiod and light intensity) on growth, survival, and behavior of American lobster postlarvae (stage IV) at release time. Results showed that photophase length did not induce any significant differences in growth and survival at 100 lx. Light intensity did not affect larval development at 16 h photophase. Results showed a significant interaction between the two factors (photoperiod and light intensity) on larval survival, but not on growth. When compared to other studies, our results indicate that the feeding time (night vs. day) may be of importance for optimizing growth and survival of early larvae. Behavior results clearly demonstrated that the age of the lobster at postlarvae stage IV had more influence than the day length or light intensity, and that the light intensity induced more variability than the day length. The results suggest that a light regime of 16 h photophase at 1000 lx light intensity, both survival and settling behavior at release time.

Implications of physical key factors in the early rearing of the long-snouted seahorse Hippocampus guttulatus

Abstract Although breeding conditions are rather well established for some seahorse species ( Hippocampus spp.), zootechnics and the effect of non-biological factors are still unknown for many species. The present study is focussed on the effects of aquarium type/design, photoperiod regime and aeration level on the early performance (growth and survival) of Hippocampus guttulatus juveniles. Three aquarium types were evaluated: pseudoKreisel, spherical and rectangular. Juveniles grown in pseudoKreisel aquaria showed lower growth rates but significantly higher survivals (69 ± 15%) at day 30 after male's pouch release (DAR) when compared to either spherical (30 ± 22%) or rectangular (16 ± 12%) aquaria. Survival enhancement in pseudoKreisel aquaria was mainly related to the very lower proportion of juveniles showing swim bladder hyperinflation during the first days of life. Conversely, the other aquarium types did not avoid juveniles to remain near water surface and to gulp air in excess for swim bladder inflation. The effects of light regime and aeration level were assayed in H. guttulatus juveniles reared in all three aquarium types or in pseudoKreisel aquaria only, respectively. In general, the application of extended (continuous light) or natural photoperiods (day–night cycle; 16 h light:8 h dark) did not affect survival nor growth significantly. On the other hand, aeration levels in pseudoKreisel aquaria significantly affected juvenile survival. Survivals in 30 day old seahorses reared under a strong aeration were significantly higher (41 ± 12%) than when reared under weak aeration (13 ± 0%). Strong aeration levels enhanced the distribution of juveniles in the aquaria and diminished both their over-exposition to water surface and the resulting appearance of hyperinflation problems. The overall results suggest that the best rearing conditions were met when H. guttulatus juveniles grew in pseudoKreisel aquaria under both a strong aeration level and, to a lesser extent, a natural photoperiod regime, due to a slight enhancement in seahorse juvenile performance.

Effects of light regime on diurnal plasma melatonin levels and vertical distribution in farmed Atlantic cod (Gadus morhua L.)

Two studies were performed to study the effect of different light intensities on melatonin secretory profiles in Atlantic cod (Gadus morhua L.). In an indoor tank study, plasma melatonin profiles were measured over a 24-hour cycle in juvenile Atlantic cod reared under a 12h light:12h dark photoperiod, having either a high or low daytime light intensity (15.5 or 0.16μE·cm−2·s−1). In a second study, plasma melatonin levels were measured in Atlantic cod kept in traps at three depths (4, 9 and 14m) in a large sea cage following exposure to the following five experimental light regimes: (1) natural light (NL), (2) NL+artificial constant light (LL) at 2, 7 and 12m depth, (3) NL+LL at 2 or 12m, (4) NL+LL at 2m and (5) NL+LL at 2m together with additional surface shading. The vertical distribution of free swimming Atlantic cod in the same sea cage was monitored using hydroacoustics. In the tank experiment, diurnal plasma melatonin profiles were similar under low and high light intensity, remaining low during the light period, then increasing rapidly within 15–30min of lights off, before peaking around midnight. In the sea cage experiment, fish under NL showed a similar diurnal rhythm in plasma melatonin levels, with high melatonin levels during the dark period, although at sunrise melatonin levels started to fall earlier in fish kept at 4m depth compared to fish kept at 9 and 14m. Overall, melatonin profiles were most effectively reduced, in terms of relative (day/night) plasma levels, in those fish sampled at the deepest depth (14m). Relative plasma melatonin levels were correlated to the distance from the artificial light source and the intensity of the ambient light. Dispersed light (lamps at 2, 7 and 12m) was the most effective light regime for inhibiting the nocturnal rise in plasma melatonin ratios in fish sampled at all three depths. Finally, exposure to the different light regimes did not influence the vertical distribution of Atlantic cod within the sea cage, which consistently remained close to the bottom of the cage.

Effects of light regimes on in vitro seed germination and silymarin content in Silybum marianum

Silybum marianum is an economically important crop worldwide. It is renowned for production of biologically important silymarin. Average sale of silymarin is about US$ 8 billion/annum and its demand varies from 18 to 20tons/year. Despite of its demand, there is lack of research efforts on cultivation and improvement of this plant. We hereby established feasible seed germination protocol for production of healthier and chemically consistent plantlets. Combination of benzyladenine (BA, 0.5mgl−1)+gibberellic acid (GA3, 1.5mgl−1)+thidiazuron (TDZ, 1.0mgl−1) produced optimum germination frequency in seeds kept in 2 weeks dark and subsequently transferred to 2 weeks light (16h photoperiod) conditions. Correlation among mean shoot length, mean root length, set of antioxidative enzyme activities was also observed in current report. Silymarin was determined by high performance liquid chromatography (HPLC). Considerable amount of silymarin (5.48mgg−1DW) was detected in our study, which was comparative to other reports available. Antioxidant activity (1,1-diphenyl-2-picrylhydrazyl; FRSA) and phenylalanine ammonia lyase (PAL) activity was also determined. Silymarin content had shown direct relationship with these activities. It showed that silymarin was a major antioxidant in current report. This study provides basis for expedited production of S. marianum plantlets with feasible content of silymarin.

Seed germination of Pinus koraiensis in response to light regimes caused by shading and seed positions

Pinus koraiensis Siebold & Zucc. (Korean pine), the dominant tree species in the mixed broadleaved Korean pine forests (regional climax), is severely restricted by its regeneration failure. To determine the effects of light regimes on P. koraiensis regeneration, the seed germination process was examined in shade houses and forest stands (before and after leaf expansion) with various light levels created by shading and seed positions. Despite the large size of P. koraiensis seeds (500-600 mg), both light intensity and quality significantly affected the germination percentage in both shade houses and forests. Substantial changes in light intensity and quality led the majority of seeds (80%) to germinate in leafless forests and shade houses, while only a minority (≤ 20%) germinated after leaf expansion in the forests. Moreover, seed germination in shade houses and leafless forests exhibited similar patterns; they consistently reached a 70% shading degree, which was optimal for the seed germination of P. koraiensis on topsoil. Seed positioning significantly affected germination for each shading degree, especially when litter and soil coverings drastically inhibited germination. In conclusion, (1) when seeds were not stressed by temperature and moisture, light irradiance played a critical role in the seed germination of P. koraiensis; (2) seed positioning, in relation to alterations in light intensity and quality, affected the germination of P. koraiensis; (3) a shade house experiment using neutral cloth provided an applicable and controllable way to monitor the P. koraiensis seed germination in early spring before leaf expansion. The light requirement for the germination of P. koraiensis played a key role in the regeneration of P. koraiensis throughout the temperate secondary forests.

Effects of light regimes on photosynthetic characteristics and antioxidant system in seedlings of two alder species

Aims Our objective was to investigate the effects of different light intensities on leaf morphology, photosynthetic capacity, heat dissipation and antioxidant enzyme activities in seedlings of Alnus formosana and A. cremastogyne from a hilly region near Lingyan Mountain in northwestern Sichuan Province in China. We also discuss photosynthetic acclimation and photoprotection strategies in seedlings of the two species Methods Three light regimes of 100%, 56.2% and 12.5% of natural light were simulated to match forest openings, forest gaps and forest canopies, respectively. After more than three months, we measured the parameters of gas exchange, including maximum net photosynthetic rate (Pmax), light saturation point (LSP), light compensation point (LCP), net photosynthetic rate (P n ), stomatal conductance (G s ), transpiration rate (T r ), intercellular CO 2 concentration (C i ), fluorescent non-photochemical quenching (NPQ), maximum efficiency of PSII photochemistry (F v /F m ) and light use efficiency (LUE), using a LI-6400 in seedling leaves. We also determined pigment contents per unit leaf area, lamina mass per unit area (LMA) and activity of antioxidant enzymes (superoxide dismutase, catalase and ascorbate peroxidase). Important findings LMA, carotenoid content (Cars), ratio of carotenoid to total chlorophyll (Car/Chl) and activities of superoxide dismutase, catalase and ascorbate peroxidase in leaves increased with the increase of light intensities. P max , LSP, LCP and NPQ tended to increase, while the chlorophyll content (Chl) and LUE decreased. However, the C i decreased with the increase of P n , G s and stomatal limitation value (L s ). We speculated that non-stomatal limitation was the main factor that inhibited P n . Seedlings of the two alder species could acclimate to different light regimes in this study through changing of physiological and morphological traits. Under all lightregimes, diurnal photoinhibition of photosynthesis, as judged by F v /F m , was significantly more severe in A. cremastogyne than in A. formosana. The acclimation capacity to high light regime was stronger in A. formosana than in A. cremastogyne. With the increase of light intensities, P max and antioxidant enzyme activities increased significantly, but not NPQ in A. formosana. The opposite trends occurred in A. cremastogyne. At the same light intensity, thermal dissipation was much lower, but P max was much higher in A. formosana than in A. cremastogyne. These results indicated that A. formosana seedlings might adapt resistance to photoinhibition through improving the use of solar energy by higher P max and antioxidant enzyme system, while A. cremastogyne seedling avoided photoinhibition mainly through converting excess light energy to heat energy in the form of non-radiative dissipation through the antenna system.

Effect of light regime on biochemical parameters of development of stress-reactions of Musca domestica L. Lines with different lifespan

The paper presents results obtained at recording under conditions of stresses of different character of activities of enzymes (tyrosinase, DOPA-oxidase, acetylcholinesterase) and level of the catecholamine content in tissues of head and fat body of imago and larvae of housefly from lines with different lifespan. A suggestion is put forward about different mechanisms mediating photoperiodic regulation of metabolism in individuals with different intensity of metabolism.

Effect of the Light Regime and Phototrophic Conditions on Growth of the H2-producing Green Alga Chlamydomonas Reinhardtii

Development of the capacity to produce hydrogen economically from renewable energy resources is of critical importance to the future viability of that fuel. The inexpensive and widely available green alga Chlamydomonas reinhardtii has the ability to photosynthetically synthesise molecular hydrogen. Green algal hydrogen production does not generate any toxic or polluting bi-products and could potentially offer value-added products derived from algal biomass. The growth of dense and healthy algal biomass is a vital requirement for efficient hydrogen production. Algal cell density is principally limited by the illumination conditions of the algal culture and by the availability of key nutrients, including the sources of carbon, nitrogen, sulphur and phosphorus. In this study, the effect of different light regimes and carbon dioxide feeds on Chlamydomonas reinhardtii growth were investigated. The objective was to increasing the algal growth rate and the cell density, leading to enhanced biohydrogen production. State-of-the art photobioreactors were used to grow algal cultures, and to measure the pH and optical density of those cultures. Under mixotrophic growth conditions, using both acetate and carbon dioxide, increasing the carbon dioxide feed rate increased the optical density of the culture but reduced the growth rate. Under autotrophic growth conditions, with carbon dioxide as the only carbon source, a carbon dioxide feed with a partial pressure of circa 11% was determined to optimise both the algal growth rate and the optical density.

The effects of light regimes and hormones on corneal growth in vivo and in organ culture

When chicks are exposed to constant light (CL) during growth, their corneas become flatter and lighter in weight, and their anterior segments become shallower than those of chicks exposed to cyclical periods of light and dark. These effects have been correlated with CL suppression of cyclical changes in melatonin levels. The question of whether light directly influences corneal growth (e.g. via cryptochromes in the cornea) or acts remotely via the suppression of the melatonin rhythm has not yet been answered. Retinoic acid (RA), an ubiquitous morphogen, also causes non-functional flattening during corneal growth, but its effect in vivo has not been correlated with light regimes. We wished to characterize and distinguish between hormonal and light effects on corneal growth. We used organ culture to study the direct effects of light regimes, melatonin, and RA, and compared these results with those of parallel in vivo experiments. In this study, eye drops containing melatonin or RA were applied to corneas exposed to CL in vivo or in organ culture, and effects on corneal mass and hydration were measured. We applied a melatonin blocker, luzindole, to chick corneas in normal light/dark conditions to confirm that the observed melatonin effects are mediated at the cell membrane. Anterior chamber depth and refraction in vivo were measured. We found that, during CL exposure, combined application of melatonin and RA eye drops increased the depth of the anterior segment in vivo, (P = 0.003) and interestingly, both also reduced the hyperopia of CL exposure after 2 weeks (P = 0.002), thus partially reversing the effects of CL. RA increased corneal hydration in vivo (P = 0.030) but not in organ culture. Melatonin had no effect on corneal hydration in vivo, but in organ culture, melatonin significantly decreased hydration (P < 0.001). We found no evidence for a direct effect of light on corneal hydration in growing chick corneas in culture. Melatonin is required for normal corneal growth in vivo, and together melatonin and RA, or RA alone, affects the regulation of water content within the chick cornea. Melatonin also affects corneal hydration in vitro, but RA does not.

Effects of post-eclosion light-dark regimes on mating performance of mass-reared tephritid fly Anastrepha ludens

Many insect species show daily rhythms in their reproductive behaviour, with male and female cycles often being synchronized by photoperiod. In mass-rearing facilities, many environmental factors, including photoperiod, are standardized to favour insect production. However, these standardizations could affect sexual performance. Herein we studied, under semi-natural conditions, the effect of different photoperiods on the copulation behaviour of mass-reared Anastrepha ludens Loew (Diptera: Tephritidae) flies. Adult flies were exposed to six combinations of light conditions during the first 12 days after eclosion: (1) 12 days under a L12:D12 h regime (12-LD), (2) 8 days under L12:D12 followed by 4 days in complete darkness (8-L:4-D), (3) 4 days under L12:D12, then 8 days in darkness (4-L:8-D), (4) 12 days in darkness (12-D), (5) 8 days in darkness, then 4 days under L12:D12 (8-D:4-L), and (6) 4 days in darkness followed by 8 days under L12:D12 (4-D:8-L). On day 13, field-cage tests were carried out to determine fly mating performance. There was a sex-specific effect of light regime on fly copulation behaviour. Females exposed to absolute darkness during periods longer than 4 days had fewer copulations compared with females subjected to other light regimes. In contrast, periods of darkness of 8 or 12 days immediately before the field test affected male mating performance. There was no significant difference in the latency to copulation or in copula duration among males or females of the six treatments. We conclude that a period of 4 days under dark conditions does not affect male mating performance. We discuss our results in terms of the light conditions encountered by mass-reared tephritids when emerging in packing devices, which may negatively affect their sexual performance once released in the field.

Effects of Light Regime, Temperature, and Plant Age on Uptake of Arsenic by Spartina Pectinata and Carex Stricta

We report here on efforts to show that a combination of native wetland plant species might perform better than a monoculture in wetlands designed for arsenic remediation by supplementing weaknesses. Carex stricta and Spartina pectinata were used in hydroponic experiments. (i) Arsenic uptake was first assessed at two ages via exposure to control or arsenic-laden solutions (0 or 1.5 mg As L−1 as Na2HAsO4) for two weeks. Age had no significant effect on arsenic concentrations in roots, but translocation factors were greater in older plants of C. stricta and S. pectinata (0.45 and 0.07, respectively) than in younger plants (0.10 and 0.01, respectively). (ii) Seasonal effects were assessed by determining uptake kinetics for both species in conditions representative of spring temperatures (15/5°C) and light regimes (1050 μmol m−2 s−1, 13 h day−1) and summer temperatures (28/17°C) and light regimes (1300 μmol m−2 s−1, 15 h day−1). Both species had comparable rates of arsenic uptake into roots in summer conditions (44.0 and 46.5 mg As kg−1 dry wt. h−1 in C. stricta and S. pectinata, respectively), but C. stricta had a higher maximum net influx rate in spring conditions (24.5 versus 10.4 mg As kg−1 dry wt. h−1).

Soil pro pert ies in sessile oak fore sts (Quercetum montanum typicum Cer. et Jov. 1953) in the are a of Fruska Gora

The soils formed on sandstones in sessile oak forests (Quercetum montanum typicum Cer. et Jov. 1953) were researched in the area of Fruska Gora. On permanent sample plots established in management units ?Cortanovacka Forest-Hopovo-Velika Remeta? and ?Beocin-Manastir-Katanske Livade-Osovlje?, in the are of NP ?Fruska Gora?, aiming at the monitoring of the effect of light regime on the development of sessile oak progeny in the given environmental conditions, based on the morphogenetic characteristics of the soil and analytic values of the soil properties, and based on the soil classification by Skoric et al. (1985), the following two soil types were defined: acid brown soil (dystric cambisol), and illimerised soil (luvisol). Acid brown soil belongs to the form of medium deep soils, and illimerised soil is classified as deep soil.

Effects of light regime and oxygen profile on transformation of oxolinic acid in pond sediment

This study investigated the effects of light (visible light – 5800 lux, 24 h) or dark regime and aerobic or anaerobic condition on the decay of added oxolinic acid (OA) at 5, 10 and 20 mg L −1 in eel pond sediment. An asymptotic decaying exponential model C t = C min + C o × exp (− k × t) was used to facilitate quantitative approach to OA transformation, where C t is the concentration of OA after t days, C min the estimated level-off concentration of OA residue, C o the concentration of added OA and k the decaying coefficient. OA decayed faster under light ( C min = 4.6 mg L −1) than under dark ( C min = 7.8 mg L −1) and also decayed faster under aerobic ( C min = 4.0 mg L −1) than under anaerobic condition ( C min = 8.5 mg L −1). C min increased with C o . Sundrying and tilling eel pond bottom should be able to reduce OA residue significantly.

Effect of light regimes on the utilisation of an exogenous carbon source by freshwater biofilm bacterial communities

This study reports the novel use of nucleic acid stable isotope probing (NA-SIP) to identify metabolically active ([13C]-acetate assimilating) bacteria in freshwater biofilms. Currently, a little is known of the factors affecting the structure and activity of these complex microbial biofilm communities, although it is likely that they are influenced by riparian vegetation through attenuation of light and alteration of allochthonous inputs of carbon. NA-SIP was used to investigate the effect of varying light regimes on [13C]-acetate assimilating bacteria within laboratory biofilm microcosms. Differences in clone libraries of 16S rRNA and rRNA genes from 13C-labelled and unlabelled nucleic acids indicated differential uptake of acetate and the rapid transfer of 13C to organisms at a higher trophic level. Biofilm communities incubated in the dark changed least over time and retained a significant fraction of phototrophic organisms. Incubation under elevated light caused the greatest change in bacterial community structure. Contrary to expectation, a complete loss of chlorophyll containing organisms occurred within this treatment, challenging current thinking that elevated light promotes communities dominated by photoautotrophs in nutrient enriched environments.

Digestive efficiency, free amino acid pools and quality of growth performance in Atlantic salmon (Salmo salar L.) affected by light regimes and vaccine types

This study comprised the results of three different seawater trials using unique combination of techniques to study protease digestive efficiency and growth performance quality to illustrate the effects of light regimes and vaccine types in Atlantic salmon (Salmo salar L.). Fish with higher growth had higher trypsin (T) and chymotrypsin (C) specific activities with higher T/C ratio or slope T/C ratio [calculated from the regression between trypsin (y) and chymotrypsin (x) specific activities] in the pyloric caeca. The T/C ratios indicated fish growth rates over a period of 1-2 months, while the slope T/C ratios indicated fish growth rates at sampling. Adaptation period for adjustment to the new environment of continuous light was 70 days, indicated by the differences in trypsin specific activities and the crossing of slope T/C ratio regressions following with the changes in growth rate directions between the control and the treated group. Vaccine types affected fish vertebral growth, and additional continuous light enhanced the impact of vaccines on fish growth during springtime, indicated by differences in slope T/C ratios. Continuous light stimulated fish growth during winter to spring, when the natural day length was short, without significantly changing white muscle and oocyte qualities in the fish of about 500 g, except for significantly increased white muscle RNA concentration. Continuous light also reduced fish growth rate later during summer, when the natural day length was long, by precedently decreasing the T/C ratio in late spring. Interestingly, plasma levels of free lysine related to tryptic digestion were correlated with trypsin specific activity levels. Continuous light caused higher levels of most free amino acids (FAA) involved in nitrogen metabolism, higher incorporation of essential FAA for protein synthesis, and higher protein turnover rate (free hydroxyproline levels) in both plasma and white muscle. However, continuous light did not affect higher protein content, intracellular buffering capacity and RNA levels in the white muscle of the fish of about 1 kg, probably due to limitation of FAA available for protein synthesis. It is therefore suggested that enhancing fish growth by continuous light stimulation should be accompanied by increasing availability or content of dietary protein (and probably minerals), which in turn would improve the quality of fish growth performance through increasing fillet protein concentration, strengthening vertebral growth, and delaying oocyte development.

Effects of shade on the development and sugar metabolism of coffee (Coffea arabica L.) fruits

Coffee fruits grown in shade are characterized by larger bean size than those grown under full-sun conditions. The present study assessed the effects of shade on bean characteristics and sugar metabolism by analyzing tissue development, sugar contents, activities of sucrose metabolizing enzymes and expression of sucrose synthase-encoding genes in fruits of coffee (Coffea arabica L.) plants submitted to full-sun (FS) and shade (SH) conditions. Evolution of tissue fresh weights measured in fruits collected regularly from flowering to maturation indicated that this increase is due to greater development of the perisperm tissue in the shade. The effects of light regime on sucrose and reducing sugar (glucose and fructose) contents were studied in fresh and dry coffee beans. Shade led to a significant reduction in sucrose content and to an increase in reducing sugars. In pericarp and perisperm tissues, higher activities of sucrose synthase (EC 2.4.1.13) and sucrose-phosphate synthase (SPS: EC 2.4.1.14) were detected at maturation in the shade compared with full sun. These two enzymes also had higher peaks of activities in developing endosperm under shade than in full sun. It was also noted that shade modified the expression of SUS-encoding genes in coffee beans; CaSUS2 gene transcripts levels were higher in SH than in FS. As no sucrose increase accompanied these changes, this suggests that sucrose metabolism was redirected to other metabolic pathways that need to be identified.

Effects of interlighting on yield and external fruit quality in year-round cultivated cucumber

The effects of interlighting and of the proportion of interlight on the yield and fruit quality of year-round cultivated cucumber ( Cucumis sativus L. cv. Cumuli) were investigated for this study. Artificial lighting was provided by high pressure sodium (HPS) lamps and the lighting regimes included top lighting (TL), top + interlighting 24% (T + IL24) and top + interlighting 48% (T + IL48). In TL, all of the lamps were mounted above the canopy. In T + IL24 and T + IL48, top lamps covered 76 and 52% of the lighting, respectively, while 24 and 48% of the lighting came from interlighting lamps which were mounted vertically 1.3 m above the ground between the single plant rows. The outdoor daily light integral (DLI) varied greatly during the cultivation periods; the mean values were 36.8, 5.3 and 19.9 mol m −2 day −1 for the summer, autumn–winter and spring stands, respectively. Lighting regime affected both yield and external fruit quality. Interlighting increased first class yield and decreased unmarketable yield, both in weight and number. The increase in the annual first class yield in weight was 15% in the two T + IL regimes. Interlighting improved energy use efficiency in lighting, being for the whole year 120, 130 and 127 g total yield kW h −1 in TL, T + IL24 and T + IL48, respectively. Interlighting increased the fruit skin chlorophyll concentration in all seasons, but had only a minor effect on the fruit dry matter concentration. The mean total chlorophyll concentration in fruit skin was 70.8, 76.7 and 82.2 μg cm −2 in TL, T + IL24 and T + IL48, respectively. In addition, interlighting extended the post-harvest shelf life of cucumber fruits in spring. Besides interlighting per se, also the higher proportion of interlight tended to further improve the fruit quality. For example, the fruit skin chlorophyll concentration increased along with the higher proportion of interlighting. In general, the effects of lighting regime were more prominent in lower natural light conditions in winter and spring. It is concluded that interlighting is a recommendable lighting method in cucumber cultivation, especially in lower natural light conditions.