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Light Period (light + period)
Selected AbstractsDoes timing of daily feeding affect growth rates of juvenile three-spined sticklebacks, Gasterosteus aculeatus L?ECOLOGY OF FRESHWATER FISH, Issue 3 2001M. Ali Abstract , To assess the consequences of unpredictability in the availability of food, this study measured the effect of timing of the daily feeding on food consumption and growth rates of juvenile Gasterosteus aculeatus. The experiment lasted 21 days at 14 °C and a photoperiod of 10 hours of light and 14 hours of dark. Fish were housed individually and allocated at random to three treatments. The mean initial weight of fish was 0.402 g. Group 1 were fed live enchytraeid worms for 2 h after lights came on ("morning"), group 2 was offered food for 2 h randomly at any time of the day ("random") during the light period and group 3 received food for 2 h before the lights went off ("evening"). There was no significant effect of timing of feeding on mean daily food consumption, which was 0.052 g day,1. Daily consumption on the random schedule was more irregular than on the two fixed schedules. Timing of feeding had no significant effect on mean specific growth rate (G) (2.42% day,1), gross growth efficiency (23.3%), white muscle RNA:DNA ratio (5.6), carcase lipid content (31.7% dry wt) and carcase dry matter content (27.4% wet wt). Thus, a lack of predictability in the availability of food during the light period of the day did not impose a detectable cost on the growth performance of the stickleback., [source] CYSTATIN ACCUMULATION IN TOMATO LEAVES AFTER METHYL JASMONATE TREATMENT OR MECHANICAL INJURYJOURNAL OF FOOD BIOCHEMISTRY, Issue 1 2002JU WEN WU The elicitation of cystatin accumulation in tomato leaves was studied with mature and seedling cv. Bonnie Best. Repetitive mechanical injury (MI) or methyl jasmonate (MJ) treatment of seedlings elicited plentiful cystatin accumulation in the leaves when plants were held at 30C under continuous lighting. Cystatin accumulation in leaves of MI seedlings decreased by 50% when incubated at a reduced light period of 12 h light/day. Cystatin accumulation in MJ treated plants was not influenced by reducing the light period from 24 h to 12 h/day. Cystatin accumulation after MJ treatment was optimal at 35C and negligible at 40C. At ambient field conditions (I8,33C), MJ treated seedlings still accumulated a significant amount of cystatin; however, very little cystatin accumulated in leaves of MI seedlings under these conditions of lower temperature and light exposure. The leaves of mature plants accumulated less cystatin after MJ or MI treatment than did those of seedlings. [source] Rhythm-Dependent Light Induction of the c-fos Gene in the Turkey HypothalamusJOURNAL OF NEUROENDOCRINOLOGY, Issue 6 2007A. Thayananuphat Day length (photoperiod) is a powerful synchroniser of seasonal changes in the reproductive neuroendocrine activity in temperate-zone birds. When exposed to light during the photoinducible phase, reproductive neuroendocrine responses occur. However, the neuroendocrine systems involved in avian reproduction are poorly understood. We investigated the effect of light exposure at different circadian times upon the hypothalamus and components of the circadian system, using c-fos mRNA expression, measured by in situ hybridisation, as an indicator of light-induced neuronal activity. Levels of c-fos mRNA in these areas were compared after turkey hens (on a daily 6-h light period) had been exposed to a 30-min period of light occurring at 8, 14, or 20 h after the onset of first light of the day (subjective dawn). Non-photostimulated control birds were harvested at the same times. In birds, photostimulated within the photoinducibile phase (14 h), in contrast to before or after, c-fos mRNA was significantly increased in the nucleus commissurae pallii (nCPa), nucleus premamillaris (PMM), eminentia mediana (ME), and organum vasculosum lamina terminalis (OVLT). Photostimulation increased c-fos mRNA expression in the pineal gland, nucleus suprachiasmaticus, pars visualis (vSCN) and nucleus inferioris hypothalami compared to that of their corresponding nonphotostimulated controls. However, the magnitudes of the responses in these areas were similar irrespective of where in the dark period the pulses occurred. No c-fos mRNA was induced in the nucleus infundibulari, in response to the 30-min light period at any of the circadian times tested. The lack of c-fos up-regulation in the pineal gland and vSCN following photostimulation during the photoinducible phase lends credence to the hypothesis that these areas are not involved in the photic initiation of avian reproduction. On the other hand, c-fos mRNA increases in the nCPa, ME, and OVLT support other studies showing that these areas are involved in the onset of reproductive behaviour initiated by long day lengths. The present study provides novel data showing that the PMM in the caudal hypothalamus is involved in the neuronally mediated, light-induced initiation of reproductive activity in the turkey hen. [source] Changes in Hypothalamic-Pituitary-Adrenal Function, Body Temperature, Body Weight and Food Intake with Repeated Social Stress Exposure in RatsJOURNAL OF NEUROENDOCRINOLOGY, Issue 1 2006S. Bhatnagar Abstract These present studies aimed to compare changes in hypothalamic-pituitary-adrenal (HPA) activity and body temperature in response to acute social defeat, to repeated social stress and to novel restraint after repeated stress, as well as to assess effects on metabolic parameters by measuring body weight gain and food and water intake. We found that social defeat produced a marked increase in both adrenocorticotrophic hormone and corticosterone compared to placement in a novel cage. Similarly, body temperature was also increased during social defeat and during 30 min of recovery from defeat. We then examined the effects of 6 days of repeated social stress and observed minimal HPA responses to repeated social stress compared to control rats. These neuroendocrine responses were contrasted by robust increases in body temperature during stress and during recovery from stress during 6 days of repeated stress. However, in response to novel restraint, repeatedly stressed rats displayed facilitated body temperature responses compared to controls, similar to our previous findings with HPA activity. Food intake was increased during the light period during which defeat took place, but later intake during the dark period was not affected. Repeated stress decreased body weight gain in the dark period but food intake was increased overall during the 6 days of repeated stress in the light period. As a result, repeated stress increased cumulative food intake during the light period in the stressed rats but these relatively small increases in food intake were unable to prevent the diminished total weight gain in repeatedly stressed rats. Overall, the results demonstrate that, although acute social defeat has similar effects on temperature and HPA activity, repeated exposure to social stress has divergent effects on HPA activity compared to body temperature and that dampened weight gain produced by repeated social stress cannot be fully explained by changes in food intake. [source] MORPHOLOGICAL CHANGES IN MITOCHONDRIAL AND CHLOROPLAST NUCLEOIDS AND MITOCHONDRIA DURING THE CHLAMYDOMONAS REINHARDTII (CHLOROPHYCEAE) CELL CYCLE,JOURNAL OF PHYCOLOGY, Issue 5 2006Takayoshi Hiramatsu Morphological changes in the organellar nucleoids and mitochondria of living Chlamydomonas reinhardtii Dang were examined during the cell cycle under conditions of 12:12 light:dark. The nucleoids were stained with SYBR-Green I, and the mitochondria were stained with 3,3-dihexyloxacarbocyanine iodide. An mocG33 mutant, which contains one large chloroplast nucleoid throughout the cell cycle, was used to distinguish between the mitochondrial and chloroplast nucleoids. Changes in the total levels of organellar DNA levels were assessed by real-time PCR. Each of the G1, S, M, and Smt,cp phases was estimated. At the start of the light period, the new daughter cells were in G1 and contained about 30 mitochondrial and 10 chloroplast nucleoids, which were dispersed and had diameters of 0.1 and 0.2 ,m, respectively. During the G1 phase of the light period, and at the start of the S phase, both nucleoids formed short thread-like or bead-like structures, probably divided, and increased continuously in number, concomitantly with DNA synthesis. The nucleoids probably became smaller due to the decrease in DNA of each particle and were indistinguishable. The cells in the S and M phases contained extremely high numbers of scattered nucleoids. However, in the G1 phase of the dark period, the nucleoids again formed short thread-like or bead-like structures, probably fused, and decreased in number. The mitochondria appeared as tangled sinuous structures that extended throughout the cytoplasm and resembled a single large mitochondrion. During the cell cycle, the numbers of mitochondrial nucleoids and sinuous structures varied relative to one another. [source] Thermoperiod affects the diurnal cycle of nitrate reductase expression and activity in pineapple plants by modulating the endogenous levels of cytokininsPHYSIOLOGIA PLANTARUM, Issue 3 2009Luciano Freschi Nitrate reductase (NR, EC 1.6.6.1) activity in higher plants is regulated by a variety of environmental factors and oscillates with a characteristic diurnal rhythm. In this study, we have demonstrated that the diurnal cycle of NR expression and activity in pineapple (Ananas comosus, cv. Smooth Cayenne) can be strongly modified by changes in the day/night temperature regime. Plants grown under constant temperature (28°C light/dark) showed a marked increase in the shoot NR activity (NRA) during the first half of the light period, whereas under thermoperiodic conditions (28°C light/15°C dark) significant elevations in the NRA were detected only in the root tissues at night. Under both conditions, increases in NR transcript levels occurred synchronically about 4 h prior to the corresponding elevation of the NRA. Diurnal analysis of endogenous cytokinins indicated that transitory increases in the levels of zeatin, zeatin riboside and isopentenyladenine riboside coincided with the accumulation of NR transcripts and preceded the rise of NRA in the shoot during the day and in the root at night, suggesting these hormones as mediators of the temperature-induced modifications of the NR cycle. Moreover, these cytokinins also induced NRA in pineapple when applied exogenously. Altogether, these results provide evidence that thermoperiodism can modify the diurnal cycle of NR expression and activity in pineapple both temporally and spatially, possibly by modulating the day/night changes in the cytokinin levels. A potential relationship between the day/night NR cycle and the photosynthetic pathway performed by the pineapple plants (C3 or CAM) is also discussed. [source] The Effect of Irradiance on Carboxylating/Decarboxylating Enzymes and Fumarase Activities in Mesembryanthemum crystallinum L. Exposed to Salinity StressPLANT BIOLOGY, Issue 1 2001Z. Miszalski Abstract: In Mesembryanthemum crystallinum plants, treated for 9 days with 0.4 M NaCl at low light intensities (80 - 90 or 95 - 100 ,E m -2 s -1; , = 400 - 700 nm), no day/night malate level differences (,malate) were detected. At high light (385 - 400 ,E m -2 s -1) strong stimulation of PEPC activity, accompanied by a ,malate of 11.3 mM, demonstrated the presence of CAM metabolism. This indicates that, to evolve day/night differences in malate concentration, high light is required. Salt treatment at low light induces and increases the activity of NAD- and NADP-malic enzymes by as much as 3.7- and 3.9-fold, while at high light these values reach 6.4- and 17.7-fold, respectively. The induction of activity of both malic enzymes and PEPC (phospoenolpyruvate carboxylase) take place before ,malate is detectable. An increase in SOD (superoxide dismutase) was observed in plants cultivated at high light in both control and salt-treated plants. However, in salt-treated plants this effect was more pronounced. Carboxylating and decarboxylating enzymes seem to be induced by a combination of different signals, i.e., salt and light intensity. Plants performing CAM, after the decrease of activity of both the decarboxylating enzymes at the beginning of the light period, showed an increase in these enzymes in darkness when the malate pool reaches higher levels. In CAM plants the activity of fumarase (Krebs cycle) is much lower than that in C3 plants. The role of mitochondria in CAM plants is discussed. [source] Stomatal responses to CO2 during a diel Crassulacean acid metabolism cycle in Kalanchoe daigremontiana and Kalanchoe pinnataPLANT CELL & ENVIRONMENT, Issue 5 2009SUSANNE VON CAEMMERER ABSTRACT To investigate the diurnal variation of stomatal sensitivity to CO2, stomatal response to a 30 min pulse of low CO2 was measured four times during a 24 h time-course in two Crassulacean acid metabolism (CAM) species Kalanchoe daigremontiana and Kalanchoe pinnata, which vary in the degree of succulence, and hence, expression and commitment to CAM. In both species, stomata opened in response to a reduction in pCO2 in the dark and in the latter half of the light period, and thus in CAM species, chloroplast photosynthesis is not required for the stomatal response to low pCO2. Stomata did not respond to a decreased pCO2 in K. daigremontiana in the light when stomata were closed, even when the supply of internal CO2 was experimentally reduced. We conclude that stomatal closure during phase III is not solely mediated by high internal pCO2, and suggest that in CAM species the diurnal variability in the responsiveness of stomata to pCO2 could be explained by hypothesizing the existence of a single CO2 sensor which interacts with other signalling pathways. When not perturbed by low pCO2, CO2 assimilation rate and stomatal conductance were correlated both in the light and in the dark in both species. [source] Elevated carbon dioxide increases nitrate uptake and nitrate reductase activity when tobacco is growing on nitrate, but increases ammonium uptake and inhibits nitrate reductase activity when tobacco is growing on ammonium nitratePLANT CELL & ENVIRONMENT, Issue 11 2001P. Matt Abstract The influence of elevated [CO2] on the uptake and assimilation of nitrate and ammonium was investigated by growing tobacco plants in hydroponic culture with 2 mm nitrate or 1 mm ammonium nitrate and ambient or 800 p.p.m. [CO2]. Leaves and roots were harvested at several times during the diurnal cycle to investigate the levels of the transcripts for a high-affinity nitrate transporter (NRT2), nitrate reductase (NIA), cytosolic and plastidic glutamine synthetase (GLN1, GLN2), the activity of NIA and glutamine synthetase, the rate of 15N-nitrate and 15N-ammonium uptake, and the levels of nitrate, ammonium, amino acids, 2-oxoglutarate and carbohydrates. (i) In source leaves of plants growing on 2 mm nitrate in ambient [CO2], NIA transcript is high at the end of the night and NIA activity increases three-fold after illumination. The rate of nitrate reduction during the first part of the light period is two-fold higher than the rate of nitrate uptake and exceeds the rate of ammonium metabolism in the glutamate: oxoglutarate aminotransferase (GOGAT) pathway, resulting in a rapid decrease of nitrate and the accumulation of ammonium, glutamine and the photorespiratory intermediates glycine and serine. This imbalance is reversed later in the diurnal cycle. The level of the NIA transcript falls dramatically after illumination, and NIA activity and the rate of nitrate reduction decline during the second part of the light period and are low at night. NRT2 transcript increases during the day and remains high for the first part of the night and nitrate uptake remains high in the second part of the light period and decreases by only 30% at night. The nitrate absorbed at night is used to replenish the leaf nitrate pool. GLN2 transcript and glutamine synthetase activity rise to a maximum at the end of the day and decline only gradually after darkening, and ammonium and amino acids decrease during the night. (ii) In plants growing on ammonium nitrate, about 30% of the nitrogen is derived from ammonium. More ammonium accumulates in leaves during the day, and glutamine synthetase activity and glutamine levels remain high through the night. There is a corresponding 30% inhibition of nitrate uptake, a decrease of the absolute nitrate level, and a 15,30% decrease of NIA activity in the leaves and roots. The diurnal changes of leaf nitrate and the absolute level and diurnal changes of the NIA transcript are, however, similar to those in nitrate-grown plants. (iii) Plants growing on nitrate adjust to elevated [CO2] by a coordinate change in the diurnal regulation of NRT2 and NIA, which allows maximum rates of nitrate uptake and maximum NIA activity to be maintained for a larger part of the 24 h diurnal cycle. In contrast, tobacco growing on ammonium nitrate adjusts by selectively increasing the rate of ammonium uptake, and decreasing the expression of NRT2 and NIA and the rate of nitrate assimilation. In both conditions, the overall rate of inorganic nitrogen utilization is increased in elevated [CO2] due to higher rates of uptake and assimilation at the end of the day and during the night, and amino acids are maintained at levels that are comparable to or even higher than in ambient [CO2]. (iv) Comparison of the diurnal changes of transcripts, enzyme activities and metabolite pools across the four growth conditions reveals that these complex diurnal changes are due to transcriptional and post-transcriptional mechanisms, which act several steps and are triggered by various signals depending on the condition and organ. The results indicate that nitrate and ammonium uptake and root NIA activity may be regulated by the sugar supply, that ammonium uptake and assimilation inhibit nitrate uptake and root NIA activity, that the balance between the influx and utilization of nitrate plays a key role in the diurnal changes of the NIA transcript in leaves, that changes of glutamine do not play a key role in transcriptional regulation of NIA in leaves but instead inhibit NIA activity via uncharacterized post-transcriptional or post-translational mechanisms, and that high ammonium acts via uncharacterized post-transcriptional or post-translational mechanisms to stabilize glutamine synthetase activity during the night. [source] Reciprocal diurnal changes of phosphoenolpyruvate carboxylase expression and cytosolic pyruvate kinase, citrate synthase and NADP-isocitrate dehydrogenase expression regulate organic acid metabolism during nitrate assimilation in tobacco leavesPLANT CELL & ENVIRONMENT, Issue 11 2000W.-R. Scheible ABSTRACT Diurnal changes of transcript levels for key enzymes in nitrate and organic acid metabolism and the accompanying changes of enzyme activities and metabolite levels were investigated in nitrogen-sufficient wild-type tobacco, in transfomants with decreased expression of nitrate reductase, and in nitrate-deficient wild-type tobacco. (i) In nitrogen-sufficient wild-type plants, transcript levels for nitrate reductase (NR, EC 1.6.6.1), nitrite reductase (NIR, EC 1.7.7.1) and phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) were high at the end of the night and decreased markedly during the light period. The levels of these three transcripts were increased and the diurnal changes were damped in genotypes with decreased expression of nitrate reductase. The levels of these transcripts were very low in nitrate-limited wild-type plants, except for a small rise after irrigation with 0·2 mM nitrate. (ii) The levels of the transcripts for cytosolic pyruvate kinase (PK, EC 2.7.1.40), mitochondrial citrate synthase (CS, EC 4.1.3.7) and NADP-isocitrate dehydrogenase (NADP-ICDH, EC 1.1.1.42) were highest at the end of the light period and beginning of the night. These three transcripts increase and the diurnal changes were damped in genotypes with decreased expression of NR. (iii) The diurnal changes of transcript levels were accompanied by changes in the activities of the encoded enzymes. The activities of NR and PEPC were highest in the early part of the light period, whereas the activities of PK and NADP-ICDH were highest later in the light period and during the first part of the night and CS activity was highest at the end of the night. Activity of PEPC, PK, CS and NADP-ICDH increased and the diurnal changes were damped in genotypes with low expression of NR. Activity of all four enzymes decreased in nitrate-limited wild-type plants. (iv) In the light, malate accumulated, citrate decreased, and about 30% of the assimilated nitrate accumulated temporarily as glutamine, ammonium, glycine and serine. These changes were reversed during the night. (v) It is proposed that the diurnal changes of expression facilitate preferential synthesis of malate to act as a counter-anion for pH regulation during the first part of the light period when NR activity is high, and preferential synthesis of 2-oxoglutarate to act as a nitrogen acceptor later in the day when large amounts of nitrogen have accumulated in ammonium, glutamine and other amino acids including glycine in the photorespiration pathway, and NR activity has been decreased. [source] Intermittent hypoxia reverses the diurnal glucose rhythm and causes pancreatic ,-cell replication in miceTHE JOURNAL OF PHYSIOLOGY, Issue 3 2008Takuya Yokoe Obstructive sleep apnoea (OSA) and type 2 diabetes frequently co-exist and potentially interact haemodynamically and metabolically. However, the confounding effects of obesity have obscured the examination of any independent or interactive effects of the hypoxic stress of OSA and the hyperglycaemia of type 2 diabetes on haemodynamic and metabolic outcomes. We have developed a chronically catheterized, unhandled, lean murine model to examine the effects of intermittent hypoxic (IH) exposure and exogenous glucose infusion on the diurnal pattern of arterial blood pressure and blood glucose, as well as pancreatic ,-cell growth and function. Four experimental groups of adult male C57BL/J mice were exposed to 80 h of (1) either IH (nadir of inspired oxygen 5,6% at 60 cycles h,1 for 12 h during light period) or intermittent air (IA; control) and (2) continuous infusion of either 50% dextrose or saline (control). IH exposure during saline infusion caused a sustained increase in arterial blood pressure of 10 mmHg (P < 0.0001), reversed the normal diurnal rhythm of blood glucose (P < 0.03), doubled corticosterone levels (P < 0.0001), and increased replication of pancreatic ,-cells from 1.5 ± 0.3 to 4.0 ± 0.8% bromodeoxyuridine (BrdU)-positive) ,-cells. The combined stimulus of IH exposure and glucose infusion attenuated the hypertension, exacerbated the reversed diurnal glucose rhythm, and produced the highest rates of apoptosis in ,-cells, without any additive effects on ,-cell replication. We conclude that, in contrast to the development of sustained hypertension, IH impaired glucose homeostasis only during periods of hypoxic exposure. IH acted as a stimulus to pancreatic ,-cell replication, but the presence of hyperglycaemia may increase the hypoxic susceptibility of ,-cells. This model will provide a basis for future mechanistic studies as well as assessing the metabolic impact of common comorbities in OSA, including obesity, insulin resistance and type 2 diabetes. [source] Plastidic metabolite transporters and their physiological functions in the inducible crassulacean acid metabolism plant Mesembryanthemum crystallinumTHE PLANT JOURNAL, Issue 3 2000Rainer E. Häusler Summary The inducible crassulacean acid metabolism (CAM) plant Mesembryanthemum crystallinum accumulates malic acid during the night and converts it to starch during the day via a pathway that, because it is located in different subcellular compartments, depends on specific metabolite transport across membranes. The chloroplast glucose transporter (pGlcT) and three members of the phosphate translocator (PT) family were isolated. After induction of CAM, transcript amounts of the phosphoenolpyruvate (PEP) phosphate translocator (PPT) and the glucose-6-phosphate (Glc6P) phosphate translocator (GPT) genes were increased drastically, while triose phosphate (TP) phosphate translocator (TPT) and the pGlcT transcripts remained unchanged. PPT- and GPT-specific transcripts and transporter activities exhibited a pronounced diurnal variation, displaying the highest amplitude in the light. pGlcT transcripts were elevated towards the end of the light period and at the beginning of the dark period. These findings, combined with diurnal variations of enzyme activities and metabolite contents, helped to elucidate the roles of the PPT, GPT, TPT and pGlcT in CAM. The main function of the PPT is the daytime export from the stroma of PEP generated by pyruvate orthophosphate:dikinase (PPDK). The increased transport activity of GPT in the light suggests a higher requirement for Glc6P import for starch synthesis rather than starch mobilization. Most likely, Glc6P rather than 3-phosphoglycerate or triose phosphates is the main substrate for daytime starch biosynthesis in M. crystallinum plants in which CAM has been induced (CAM-induced), similar to non-green plastids. In the dark, starch is mobilized both phosphorylytically and amylolytically and the products are exported by the GPT, TPT and pGlcT. The transport activities of all three phosphate translocators and the transcript amounts of the pGlcT adapt to changing transport requirements in order to maintain high metabolic fluxes during the diurnal CAM cycle. [source] Effects of Monochromatic Light on Proliferation Response of Splencyte in BroilersANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 5 2008D. Xie Summary To investigate the effects of various monochromatic lights on splenocyte proliferation responses, a total of 260 Arbor Acre male broilers on P1 (post-hatching day 1) were exposed to blue light (BL), green light (GL), red light (RL) and white light treatments by light emitting diode system for 7 weeks, respectively. All light sources were equalized on the intensity of 15 lx and light period of 23 h daily. Morphological change of spleen and response of splenocyte proliferation were assessed by using histochemistry staining and colorimetric test in cultures of purified splenic cells. The results were as follows: (1) At P21, GL increased significantly the spleen weight by 163.6% and spleen index by 118.8% compared with RL (P < 0.05). Until P49, BL enhanced significantly the spleen weights by 42.2% compared with RL (P < 0.05), but no significant difference was found in the spleen index among four light-treated groups (P > 0.05). (2) Compared with RL, GL increased significantly the diameter of splenic nodule and area of periarterial lymphatic sheath at P21 by 87.2 and 58.1%, respectively (P < 0.05); BL increased significantly the diameter of splenic nodule and area of periarterial lymphatic sheath at P49 by 64.4 and 50.5%, respectively (P < 0.05). (3) At P21, GL enhanced spleen lymphocytes proliferation in response to concanavalin A compared with RL by 50.0% (P < 0.05). Until P49, the mitogenic response in BL was significantly higher (29.4%) than that of RL (P < 0.05). (4) The interleukin-2 (IL-2) bioactivity was significantly increased to 34.3% in GL than in RL at P21 (P < 0.05). Until P49, the IL-2 bioactivity in BL was significantly higher (62.2%) than that of RL (P < 0.05). (5) There was no significant difference in the nitric oxide (NO) concentration of splenocyte among RL, GL and BL groups at P21 (P > 0.05), but the concentration in RL group at P49 was significantly increased, 59.0 and 63.7% compared to that of GL and BL groups, respectively (P < 0.05). These results suggested that the monochromatic light affected splenocyte proliferation mainly because of alterations in IL-2 bioactivity and NO production in splenocyte of broiler. In early stage of broiler growth, the action of GL was obvious, while the response of BL was stronger in later stage. [source] Photic and non-photic entrainment on daily rhythm of locomotor activity in goatsANIMAL SCIENCE JOURNAL, Issue 1 2010Claudia GIANNETTO ABSTRACT We studied the photic (L/D cycle) and non-photic (restricted feeding) entrainment on the patterns of daily rhythm of total locomotor activity in goats. Six female Maltese goats were subjected to three different artificial L/D cycles: 12/12 L/D, 12/12 D/L and constant light. During the 12/12 L/D and 12/12 D/L, food and water were available ad libitum. During constant light, animals were subjected to a restricted feeding treatment. Total activity was recorded by means of an actigraphy-based data logger (Actiwatch-Mini®). Our results showed that goats exhibited clear daily rhythms of activity in 12/12 L/D cycle, 12/12 D/L cycle and constant light, although they showed FAA prior the feeding time during the restricted feeding treatment. Goats were diurnal, with activity consistently beginning promptly following the onset of light. Even when the L/D cycle was delayed by 12 h on some days, to the daily rhythm was re-established. During the constant light period, the onset of activity was linked to the time of food administration. Our study evidences two factors for the rhythm of total locomotor activity in goats: light stimuli (photic) and food access (non photic), strongly coupled to permit organisms the adaptive temporal coordination of behaviour with stable and unstable environmental periodicities. [source] Influence of sudden changes in management program on physiological and behavioral parameters in hensANIMAL SCIENCE JOURNAL, Issue 3 2004Ashraf M. KHALIL ABSTRACT The present study was designed to test the effects of sudden changes of food access and light duration on the physiological and behavioral parameters of hens. The physiological parameters investigated were heart rate (HR), body temperature (BT), and locomotor activity (LA) using a radiotelemetry system. After implantation of the telemetry transmitters, six hens were housed individually in cages under constant environmental conditions for 10 days with a photoperiod of 15 h light (04.00,19.00 hours), and food was available ad libitum at all times. After that, the same hens were subjected to a feed withdrawal trial, from 12.00 to 08.30 hours, followed by a lighting hour reduction trial by changing the time of lights-off from 19.00 to 14.00 hours. The physiological and behavioral data were recorded for 2 days before each trial, as control data. With the feed withdrawal trial, during the light and dark periods, HR and BT were significantly lower in the hens without food access than in the control. Whereas, LA was significantly lower only during the light period in the hens without food access than in the control. Further, the time spent resting increased significantly, but the time spent feeding decreased significantly in the hens without food access than in the control. Also, the number of times the cage was pecked and pecking of the feeder occured at a significantly higher level, while the number of times beaks were wiped occured at a significantly lower level in the hens without food access than in the control. With the lighting hour reduction trial, during the light period, HR and BT were significantly higher, whereas LA was significantly lower in the 'sudden light-off' treated hens than in the control. In addition, during the dark period, HR, BT and LA were significantly higher in the sudden light-off treated hens than in the control. Moreover, in the sudden light-off treated hens, the time spent preening and feeding decreased significantly, but the time spent resting increased significantly than in the control. It is concluded that sudden changes in a management program might result in many significant differences as were found in the physiological and behavioral parameters of hens in the present study. [source] Diurnal and oviposition-related changes in heart rate, body temperature and locomotor activity of laying hensANIMAL SCIENCE JOURNAL, Issue 2 2004Ashraf M. KHALIL ABSTRACT Diurnal and oviposition patterns of heart rate (HR), deep body temperature (BT) and locomotor activity (LA) in conscious and unrestrained Rhode Island Red hens were studied by a radiotelemetry system. Behavioral observations were also made on diurnal changes and during the pre- and post-laying period. Heart rate, BT and LA showed characteristic diurnal changes synchronized with a photoperiod of 15 h light and 9 h dark. In the light period, HR, BT, and LA levels were significantly higher than in the dark period (P < 0.001). Furthermore, the highest levels of these parameters were recorded just after they were fed (08.30 hours), while the lowest level was measured after lights-off and remained stable throughout the dark period. Behavioral observations indicated that during the light period the hens spent most of their time in very active movement, exhibiting various behavioral patterns. However, in the dark period the hens spent almost all their time resting. The present results suggest that performing various behavioral activities cause heat generated by muscle exertion, which plays a significant role in daily HR, BT, and LA in laying hens. However, during the 60 min before and after oviposition, LA appeared to have increased steadily toward the moment of laying, and then regressed gradually in the post-laying period to a level significantly lower than in the pre-laying period (P < 0.001). Furthermore, the pre-laying behavior of hens indicated extreme restlessness and more activity, whereas the post-laying period is characterized by less activity and increased relaxation. Consequently, laying behavior has a profound but transitory effect on HR and BT, suggesting that oviposition was probably associated with intense LA. [source] Growth and phenotype of potato plants expressing an antisense gene of P-protein of glycine decarboxylase under control of a promoter with preference for the mesophyllANNALS OF APPLIED BIOLOGY, Issue 1 2001T WINZER Summary A cDNA encoding P-protein of glycine decarboxylase was expressed in antisense orientation in leaves of potato (Solanum tuberosum cv. Solara) under control of the promoter of a P-protein gene of glycine decarboxylase from Flaveria pringlei. This promoter targets gene expression preferentially to the leaf mesophyll cells. In two of the transgenic lines, mitochondria oxidise glycine only with extremely low rates. Phenotypically, these transgenic lines were only marginally different from wild type plants under ambient carbon dioxide concentrations and indistinguishable from wild type plants when grown under 800 ppm carbon dioxide. When grown in ambient carbon dioxide, transgenic plants accumulated high amounts of glycine during the light period followed by nearly complete degradation in the following night. [source] Diel rhythm of nitrogen and carbon metabolism in the unicellular, diazotrophic cyanobacterium Crocosphaera watsonii WH8501ENVIRONMENTAL MICROBIOLOGY, Issue 2 2010Wiebke Mohr Summary We examined the diel variation in nitrogen and carbon metabolism in Crocosphaera watsonii WH8501 at the physiological and gene expression level in order to determine the temporal constraints for N2 fixation and photosynthesis. N2 fixation and photosynthesis were restricted to the dark and light periods, respectively, during a 24 h light,dark cycle. All genes studied here except one (psbA2) showed diel variations in their expression levels. The highest variation was seen in nifH and nifX relative transcript abundance with a factor of 3,5 × 103 between light and dark periods. Photosynthesis genes showed less variation with a maximum factor of about 500 and always had high relative transcript abundances relative to other genes. At the protein level, the photosystems appeared more stable than the nitrogenase complex over a 24 h light,dark cycle, suggesting that C. watsonii retains the ability to photosynthesize during the dark period of the diel cycle. In contrast, nitrogenase is synthesized daily and exhibits peak abundance during the dark period. Our results have implications for field studies with respect to the interpretation of environmental gene expression data. [source] Sleep during the Antarctic winter: preliminary observations on changing the spectral composition of artificial lightJOURNAL OF SLEEP RESEARCH, Issue 3 2008GAVIN FRANCIS Summary Antarctic Base personnel live for 3 months in winter with no natural sunlight. This project compared sleep, by actigraphy, during periods of increased exposure to white light or blue enriched light in 2003. The primary aim was to help define the optimum spectral composition and intensity of artificial environmental light. Nine men and one woman (33 ± 7 years, mean ± SD), wore activity and light monitors continuously from 28.2 to 9.10, and kept sleep diaries. Extra light was provided by light boxes (standard white, 5300 K, or prototype blue enriched, 10 000K, Philips Lighting), which were turned on in bedrooms and in communal/work areas approximately 08.00,18.00 hours. After a no-treatment control period, 28.2,20.3, sequential 4,5 week periods of first white, then blue light, were imposed with a further control period 19.9,9.10. A limited baseline study in 2002 (no interventions) similarly measured light and activity in seven men and one woman (30 ± 7 years). Daily light exposure in winter (lux, mean ± SD) was doubled in 2003 (maximum 1039 ± 281, average 64 ± 21), compared to 2002 (572 ± 276 and 30 ± 11), P < 0.05 and P < 0.01, with no differences between white and blue light. There were no major differences in sleep between light conditions in 2003. A delay in sleep timing was found in midwinter compared to control (2003, bedtime, P < 0.05, sleep start, P < 0.05, sleep end, P < 0.01) and sleep fragmentation increased (P < 0.05). Sleep efficiency was slightly higher during all blue light periods compared to all white periods (P < 0.05). The use of higher intensity light of suitable spectral composition is proposed. [source] Oxygen dynamics during submergence in the halophytic stem succulent Halosarcia pergranulataPLANT CELL & ENVIRONMENT, Issue 7 2006O. PEDERSEN ABSTRACT This study elucidated O2 dynamics in shoots and roots of submerged Halosarcia pergranulata (Salicornioideae), a perennial halophytic stem succulent that grows on flood-prone mudflats of salt lakes. Oxygen within shoots and roots was measured using microelectrodes, for plants when waterlogged or completely submerged, with shoots in light or in darkness, in a controlled environment. Net photosynthesis (PN) when underwater, at a range of dissolved CO2 concentrations, was measured by monitoring O2 production rates by excised stems. The bulky nature and apparently low volume of gas-filled spaces of the succulent stems resulted in relatively high radial resistance to gas diffusion. At ambient CO2, quasi-steady state rates of PN by excised succulent stems were estimated to be close to zero; nevertheless, in intact plants, underwater photosynthesis provided O2 to tissues and led to radial O2 loss (ROL) from the roots, at least during the first several hours (the time period measured) after submergence or when light periods followed darkness. The influence of light on tissue O2 dynamics was confirmed in an experiment on a submerged plant in a salt lake in south-western Australia. In the late afternoon, partial pressure of O2 (pO2) in the succulent stem was 23.2 kPa (i.e. ,10% above that in the air), while in the roots, it was 6.2,9.8 kPa. Upon sunset, the pO2 in the succulent stems declined within 1 h to below detection, but then showed some fluctuations with the pO2 increasing to at most 2.5 kPa during the night. At night, pO2 in the roots remained higher than in the succulent stems, especially for a root with the basal portion in the floodwater. At sunrise, the pO2 increased in the succulent stems within minutes. In the roots, changes in the pO2 lagged behind those in the succulent stems. In summary, photosynthesis in stems of submerged plants increased the pO2 in the shoots and roots so that tissues experience diurnal changes in the pO2, but O2 from the H2O column also entered submerged plants. [source] | |||||||||||||||||||||||||