Increase In Daylength Research Articles

Seasonal variation in D2/3 dopamine receptor availability in the human brain

PurposeBrain functional and physiological plasticity is essential to combat dynamic environmental challenges. The rhythmic dopamine signaling pathway, which regulates emotion, reward and learning, shows seasonal patterns with higher capacity of dopamine synthesis and lower number of dopamine transporters during dark seasons. However, seasonal variation of the dopamine receptor signaling remains to be characterized.MethodsBased on a historical database of healthy human brain [11C]raclopride PET scans (n = 291, 224 males and 67 females), we investigated the seasonal patterns of D2/3 dopamine receptor signaling. Daylength at the time of scanning was used as a predictor for brain regional non-displaceable binding of the radiotracer, while controlling for age and sex.ResultsDaylength was negatively correlated with availability of D2/3 dopamine receptors in the striatum. The largest effect was found in the left caudate, and based on the primary sample, every 4.26 h (i.e., one standard deviation) increase of daylength was associated with a mean 2.8% drop (95% CI -0.042 to -0.014) of the receptor availability.ConclusionsSeasonally varying D2/3 receptor signaling may also underlie the seasonality of mood, feeding, and motivational processes. Our finding suggests that in future studies of brain dopamine signaling, especially in high-latitude regions, the effect of seasonality should be considered.

Seasonality in regional brain glucose metabolism.

Daylength and the rates of changes in daylength have been associated with seasonal fluctuations in psychiatric symptoms and in cognition and mood in healthy adults. However, variations in human brain glucose metabolism in concordance with seasonal changes remain under explored. In this cross-sectional study, we examined seasonal effects on brain glucose metabolism, which we measured using 18F-fluorodeoxyglucose-PET in 97 healthy participants. To maximize the sensitivity of regional effects, we computed relative metabolic measures by normalizing the regional measures to white matter metabolism. Additionally, we explored the role of rest-activity rhythms/sleep-wake activity measured with actigraphy in the seasonal variations of regional brain metabolic activity. We found that seasonal variations of cerebral glucose metabolism differed across brain regions. Glucose metabolism in prefrontal regions increased with longer daylength and with greater day-to-day increases in daylength. The cuneus and olfactory bulb had the maximum and minimum metabolic values around the summer and winter solstice respectively (positively associated with daylength), whereas the temporal lobe, brainstem, and postcentral cortex showed maximum and minimum metabolic values around the spring and autumn equinoxes, respectively (positively associated with faster daylength gain). Longer daylength was associated with greater amplitude and robustness of diurnal activity rhythms suggesting circadian involvement. The current findings advance our knowledge of seasonal patterns in a key indicator of brain function relevant for mood and cognition. These data could inform treatment interventions for psychiatric symptoms that peak at specific times of the year.

Seasonal Changes in Photoperiod: Effects on Growth and Redox Signaling Patterns in Atlantic Salmon Postsmolts.

Farmed Atlantic salmon reared under natural seasonal changes in sea-cages had an elevated consumption of antioxidants during spring. It is, however, unclear if this response was caused by the increase in day length, temperature, or both. The present study examined redox processes in Atlantic salmon that were reared in indoor tanks at constant temperature (9 °C) under a simulated natural photoperiod. The experiment lasted for 6 months, from vernal to autumnal equinoxes, with the associated increase and subsequent decrease in day length. We found that intracellular antioxidants were depleted, and there was an increase in malondialdehyde (MDA) levels in the liver and muscle of Atlantic salmon with increasing day length. Antioxidant enzyme activity in liver and muscle and their related gene profiles was also affected, with a distinct upregulation of genes involved in maintaining redox homeostasis, such as peroxiredoxins in the brain in April. This study also revealed a nuclear factor-erythroid 2-related factor 2 (Nrf2)-mediated oxidative stress response in muscle and liver, suggesting that fish integrate environmental signals through redox signaling pathways. Furthermore, growth and expression profiles implicated in growth hormone (GH) signaling and cell cycle regulation coincided with stress patterns. The results demonstrate that a change in photoperiod without the concomitant increase in temperature is sufficient to stimulate growth and change the tissue oxidative state in Atlantic salmon during spring and early summer. These findings provide new insights into redox regulation mechanisms underlying the response to the changing photoperiod, and highlight a link between oxidative status and physiological function.

Possible link between Earth\u2019s rotation rate and oxygenation

The biotic and abiotic controls on major shifts in atmospheric oxygen and the persistence of low-oxygen periods over a majority of Earth’s history remain under debate. Explanations of Earth’s stepwise pattern of oxygenation have mostly neglected the effect of changing diel illumination dynamics linked to daylength, which has increased through geological time due to Earth’s rotational deceleration caused by tidal friction. Here we used microsensor measurements and dynamic modelling of interfacial solute fluxes in cyanobacterial mats to investigate the effect of changing daylength on Precambrian benthic ecosystems. Simulated increases in daylength across Earth’s historical range boosted the diel benthic oxygen export, even when the gross photosynthetic production remained constant. This fundamental relationship between net productivity and daylength emerges from the interaction of diffusive mass transfer and diel illumination dynamics, and is amplified by metabolic regulation and microbial behaviour. We found that the resultant daylength-driven surplus organic carbon burial could have shaped the increase in atmospheric oxygen that occurred during the Great and Neoproterozoic Oxidation Events. Our suggested mechanism, which links the coinciding increases in daylength and atmospheric oxygen via enhanced net productivity, reveals a possible contribution of planetary mechanics to the evolution of Earth’s biology and geochemistry.

Evaluation of seasonal breeding of the domestic canary (Serinus canaria) in an artificial environment

ABSTRACT: The domestic canary (Serinus canaria) has been bred for hundreds of years to improve the quality of its plumage and its song. Reproduction in this species occurs seasonally, stimulated by a gradual increase in day length. Although, the occurrence of seasonal breeding in canaries is well known, whether canary reproduction can be manipulated remains unknown. Our objective was to determine whether the conditions of captivity (photoperiod and temperature) can be adjusted to enable canaries to reproduce outside of their natural breeding season. Thirty days before the natural breeding season, canary pairs were assigned and separated into three different groups: External Control (housed outdoors under ambient conditions), Artificial Control (housed artificially indoors under conditions similar to the external conditions), and Artificial Altered (housed artificially indoors for five months, with the photoperiod gradually manipulated to simulate that of the natural breeding season) groups. The number of clutches laid was greater in the Artificial Control than in External Control; however, more birds hatched in the External Control. In the Artificial Altered group, the beginning of the breeding season was delayed when the same parameters were used. Although, further research is needed, this study presents new data to assist in the development of protocols that entail gradual changes in environmental conditions to try to reduce the impacts of the processes on animal welfare.

Seasonal weight changes in laboratory ferrets.

Ferrets (Mustela putorius furo) are a valuable animal model used in biomedical research. Like many animals, ferrets undergo significant variation in body weight seasonally, affected by photoperiod, and these variations complicate the use weight as an indicator of health status. To overcome this requires a better understanding of these seasonal weight changes. We provide a normative weight data set for the female ferret accounting for seasonal changes, and also investigate the effect of fluid regulation on weight change. Female ferrets (n = 39) underwent behavioural testing from May 2017 to August 2019 and were weighed daily, while housed in an animal care facility with controlled light exposure. In the winter (October to March), animals experienced 10 hours of light and 14 hours of dark, while in summer (March to October), this contingency was reversed. Individual animals varied in their body weight from approximately 700 to 1200 g. However, weights fluctuated with light cycle, with animals losing weight in summer, and gaining weight in winter such that they fluctuated between approximately 80% and 120% of their long-term average. Ferrets were weighed as part of their health assessment while experiencing water regulation for behavioural training. Water regulation superimposed additional weight changes on these seasonal fluctuations, with weight loss during the 5-day water regulation period being greater in summer than winter. Analysing the data with a Generalised Linear Model confirmed that the percentage decrease in weight per week was relatively constant throughout the summer months, while the percentage increase in body weight per week in winter decreased through the season. Finally, we noted that the timing of oestrus was reliably triggered by the increase in day length in spring. These data establish a normative benchmark for seasonal weight variation in female ferrets that can be incorporated into the health assessment of an animal’s condition.

Reproductive timing and synchronized reproduction of the sea urchin Pseudechinus magellanicus (Echinoidea: Temnopleuridae) in central Patagonia, Argentina

ABSTRACT The reproduction of the sea urchin Pseudechinus magellanicus and the influence of environmental factors were studied during a 27-month period in central Patagonia, Argentina, where this species is among the dominant grazers in kelp forests and tide pools. The monthly variation in the gonad dry weights, gonadal stages and other quantitative reproductive variables (oocyte diameter, density and thickness of spermatogenic columns) indicated a clearly annual gametogenic cycle and revealed a high level of spawning synchrony. A main spawning event occurs between August and September, and a minor and asynchronous spawning event was recorded during the austral summer (January–March). The highest gonadal growth rate occurs between late spring and summer, accompanied by growth and early prematurity gonadal stages, indicating active vitellogenesis. The accumulation of ova begins in autumn and shows a peak during winter. After spawning, the recovery stages are not extended in time and ovaries do not show a complete meshwork of nutritive phagocytes within the acinus, suggesting simultaneous reabsorption and inversion processes. Spermatogenesis shows a higher maturation rate than oogenesis, and a higher temporal prevalence of premature and mature stages. Major spawning coincides with the first rise in seawater temperature, the maximum rate of increase in day length and the maximum peak of chlorophyll a. Results also revealed some temporal differences in the gonadal cycle, vitellogenesis and spawning periods compared with other P. magellanicus populations from different latitudes. This could be attributed to individual differences in the acquisition and allocation of energy for gametogenesis, as well as to local environmental factors.

Intraspecific variation in testosterone-induced neuroplasticity in two canary strains

Temperate zone songbird species, such as the canary (Serinus canaria), can serve as model systems to investigate adult seasonal plasticity in brain and behavior. An increase in day length, experienced by canaries in the early spring stimulates gonadal recrudescence and an associated increase in circulating testosterone concentrations. This increase in plasma testosterone results in marked morphological changes in well-defined neural circuitry regulating reproductive behaviors including birdsong as well as behavioral changes such as increases in song length and complexity. An obvious measure of plasticity in neural morphology can be assessed via changes in brain nuclei volume and testosterone actions on a number of cellular features including the integration and incorporation of new neurons in the adult canary brain. Previous work in our lab suggests that there may be systematic intraspecific variability within canaries in testosterone-induced adult neuroplasticity. For example, the song nucleus HVC increases in size in response to testosterone in male canaries but we found that males of the American Singer strain exhibited minimal and variable responses as compared to other canary strains such as the Border canary strain, which is thought to be closer to wild type canaries. In this study, we systematically compared the effects of testosterone on the volume of song nuclei and the number of new neurons as assessed with the neurogenesis marker doublecortin in American Singer and Border canaries. We found more pronounced testosterone-induced neuroplasticity in the Border strain than the American Singer. These data suggest that the process of selection for certain strain phenotypes is also associated with significant changes in hormone-regulated brain plasticity.

Assessment of The role of Light in Welfare of Layers

Due to the difference in spectral sensitivity between poultry and human, there was an importance to identify the optimal light environment for the health, behavior, welfare, and production of layers. Overall birds have many types of retinal regional specializations, which have been interpreted with respect to both ecology and behavior. Light is one part of a complex of the physical phenomenon called electromagnetic radiation, which is depending on its wavelength. Light consists of 3 different aspects; intensity, photoperiod, and spectral content color. Photoperiod manipulation is likely the most important aspect of light in poultry production. Lighting programs in laying hen farms are depending on photoperiod, whereas, one hour increase in daylength leads to increase in 4 egg numbers. Overall, the use of either an increasing or intermittent lighting program will improve the welfare over those birds raised on constant light photoperiods. The light source may have an effect on leg disorders, with the use of fluorescent bulbs causing a lower incidence of the problem as compared to incandescent bulbs. Furthermore, the light intensity plays important role in poultry welfare, where the decrease in light intensities may cause lower body weights by altering behavioral patterns and can also cause eye damage, increased mortality, and a result in physiological changes in the birds. The different light colors had significant differences in all behaviors, plumage scores, foot condition, and growth performance of layers due to the presence of many types of retinal regional specializations. Thus, this article concludes that the source, spectra, intensity, and regime of light supplementation become major factors in modern poultry management.

Seasonal singing of a songbird living near the equator correlates with minimal changes in day length

Behaving in accordance with natural cycles is essential for survival. Birds in the temperate regions use the changes of day length to time their behavior. However, at equatorial latitudes the photoperiod remains almost constant throughout the year, and it is unclear which cues songbirds use to regulate behaviors, such as singing. Here, we investigated the timing of dawn-song of male silver-beaked tanagers in the equatorial lowland Amazonas over two years. In this region, birds experience around nine minutes of annual day length variation, with sunrise times varying by 32 minutes over the year. We show that the seasonal timing of dawn-song was highly regular between years, and was strongly correlated with slight increases in day length. During the singing season the daily dawn-song onset was precisely aligned to variations in twilight time. Thus, although photoperiodic changes near the equator are minimal, songbirds can use day length variation to time singing.

Duration of cambial activity is determined by water availability while cambial stimulus is day-length dependent in a Neotropical evergreen species

Experimental manipulations are essential for understanding the causal factors of plant growth and cambial activity. Here, we studied the potential effect of water availability and natural variation of day length and temperature on cambial activity in Cordiera concolor (Cham.) Kuntze, an evergreen tropical species. Experiments were conducted in a greenhouse using ninety one-year-old plants divided into two groups. Each group was observed for five weeks during two different times of the year (early spring and late summer). Plants were subjected to three distinct water regimes (waterlogging, field capacity and water deficit). Temperature and day length were recorded daily and stem samples were taken weekly during both sampling intervals. Anatomical procedures were used to describe the cambial activity per stem. Our results suggest that soil water content and its influence on cambial activity depend on the time of year, while cambial stimulus was positively related to day length, independent of the time of year. In early spring, cambial activity was stimulated by an increase of day length, regardless of water supply. In contrast, in late summer, cambial dormancy was delayed in waterlogged plants and advanced in plants subjected to a water deficit, followed by decreasing day length. Analyses of the wood anatomy showed that the marginal bands of axial parenchyma were initial. Our study highlights a more complex scenario of plant functioning and its causal factors in tropical systems.

Effect of photoperiod on growth characteristics in Chrysanthemum morifolium Ramat. cv. Zembla using high pressure sodium light

This experiment was conducted to study the effect of photoperiod on growth characteristics in chrysanthemum cv. Zembla during 1st October 2014 to 20th December 2014 in naturally ventilated greenhouse at Centre for Protected Cultivation Technology (CPCT), IARI, New Delhi. Chrysanthemum cv. Zembla was exposed under different photoperiodic treatments of day length extension illuminating from high pressure sodium (HPS) for 6, 9, 12, 15 days @ 15 h/day in growth chamber. All the growth parameters (plant height, number of leaves, internode length and leaf area)varied significantly during different stages of growth and found that the increase in photoperiod by 15 days using high pressure sodium (HPS) lighting resulted in a significant increase in stem elongation and leaf number. Increased plant height (46.25 and 42.70 cm), internodal length (2.70 and 2.63 cm) and leaf number (32.75 and 29.75) were observed in cv. Zembla due to long day extension treatments as compared to the control. Flower bud appeared at the earliest (57 days) in the plants without any exposure to the photoperiod. However, flower opening delayed with increase in day length exposure from 6 days (66 days) to 15 days (68 days) treatments. The results also revealed that supplemental high pressure sodium lighting significantly increased in plant height, internodal length as well as leaves number with increase in day length (photoperiod).

Reproductive state modulates testosterone-induced singing in adult female European starlings (Sturnus vulgaris)

European starlings (Sturnus vulgaris) exhibit seasonal changes in singing and in the volumes of the neural substrate. Increases in song nuclei volume are mediated at least in part by increases in day length, which is also associated with increases in plasma testosterone (T), reproductive activity, and singing behavior in males. The correlations between photoperiod (i.e. daylength), T, reproductive state and singing hamper our ability to disentangle causal relationships. We investigated how photoperiodic-induced variation in reproductive state modulates the effects of T on singing behavior and song nuclei volumes in adult female starlings. Female starlings do not naturally produce measureable levels of circulating T but nevertheless respond to exogenous T, which induces male-like singing. We manipulated photoperiod by placing birds in a photosensitive or photorefractory state and then treated them with T-filled or empty silastic implants. We recorded morning singing behavior for 3weeks, after which we assessed reproductive condition and measured song nuclei volumes. We found that T-treated photosensitive birds sang significantly more than all other groups including T-treated photorefractory birds. All T-treated birds had larger song nuclei volumes than with blank-treated birds (despite photorefractory T-treated birds not increasing song-rate). There was no effect of photoperiod on the song nuclei volumes of T-treated birds. These data show that the behavioral effects of exogenous T can be modulated by reproductive state in adult female songbirds. Furthermore, these data are consistent with other observations that increases in singing rate in response to T are not necessarily due to the direct effects of T on song nuclei volume.

Photoperiod control of downstream movements of Atlantic salmon Salmo salar smolts.

This study provides the first direct observations that photoperiod controls the initiation of downstream movement in Atlantic salmon Salmo salar smolts. Under simulated natural day length (LDN) conditions and seasonal increases in temperature, smolts increased their downstream movements five-fold for a period of 1 month in late spring. Under the same conditions, parr did not show changes in downstream movement behaviour. When given a shortened day length (10L:14D) beginning in late winter, smolts did not increase the number of downstream movements. An early increase in day length (16L:8D) in late winter resulted in earlier initiation and termination of downstream movements compared to the LDN group. Physiological status and behaviour were related but not completely coincident: gill Na(+) /K(+) -ATPase activity increased in all treatments and thyroid hormone was elevated prior to movement in 16L:8D treatment. The most parsimonious model describing downstream movement of smolts included synergistic effects of photoperiod treatment and temperature, indicating that peak movements occurred at colder temperatures in the 16L:8D treatment than in LDN, and temperature did not influence movement of smolts in the 10L:14D treatment. The complicated interactions of photoperiod and temperature are not surprising since many organisms have evolved to rely on correlations among environmental cues and windows of opportunity to time behaviours associated with life-history transitions. These complicated interactions, however, have serious implications for phenological adjustments and persistence of S. salar populations in response to climate change.

Influence of photoperiod on the development of diapause in larvae and its cost for individuals of a univoltine population of Dendrolimus punctatus (Lepidoptera: Lasiocampidae)

Larvae of Dendrolimus punctatus overwinter in diapause. In the Yangtze River Region, this species is multivoltine at altitudes below 400 m and univoltine above 700 m a.s.l. The photoperiodic response of the univoltine population, investigated at five day lengths (11.5, 12.5, 13.5, 14.5 and 15.5 h) at 27 + 1°C, indicates that D. punctatus is a long-day species. Diapause was induced in 95-100% of the individuals by three short photophases (11.5-13.5 h), while diapause incidence decreased steeply with increase in day length down to 10% at 15.5 h. The critical daylength (CDL = day length resulting in a 50% incidence of diapause) is 14.6 h. When induced by critical or longer photophases (14.5 and 15.5 h), diapause terminated spontaneously, without any change in photoperiod or temperature. Diapause induced at shorter photophases was more intense and not terminated without activation by diapause averting conditions. Larvae in diapause lived for up to 190 d when kept under a 11.5 h photophase during which they remained sensitive to the photoperiodic signal. In transfer experiments, diapause was terminated after an increase in photoperiod, even if it was within the range of diapause inducing photoperiods: from 11.5 h to 13.5 h. This study revealed that the univoltine hill dwelling population of D. punctatus undergoes a facultative diapause. Although potentially multivoltine they are univoltine because of the low temperatures at that altitude.

Photorefractoriness and energy availability interact to permit facultative timing of spring breeding

In seasonally breeding mammals, vernal reproductive development is not directly triggered by increases in day length, rather, an endogenous program of photorefractoriness to short winter days initiates spontaneous development in advance of spring. The transition to the reproductive phenotype is energetically demanding. How food availability in late winter and early spring impacts the onset and expression of photorefractoriness is not known. In this study, male Siberian hamsters were born into a simulated natural photoperiod, and at the winter solstice, they were subjected to a restricted feeding protocol in which a daily food ration was provided in an amount equal to ad libitum (AL) intake during the weeks preceding the solstice. Over the next several months, AL-fed control hamsters exhibited spontaneous recrudescence or spontaneous development. In contrast, vernal reproductive development was abolished in most food-rationed hamsters. In food-rationed hamsters that did exhibit recrudescence, conspicuous delays in the onset of gonadal development and decreases in the magnitude of growth were evident. In all hamsters, the termination of food rationing triggered rapid gonadal development. The data indicate that late winter/early spring increases in environmental food availability are required for the normal manifestation of photorefractoriness-induced reproductive development and suggest that a function of photorefractoriness may be merely to disinhibit the reproductive axis from photoperiodic suppression. Vernal gonadal development or recrudescence appears to be strongly affected by proximate energy availability.

Registro del año 2010 de Nutrición Parenteral Domiciliaria en España: Grupo NADYA-SENPE

Objectives: To report the Group Registry NADYASENPE data about home parenteral nutrition (HPN) in Spain in 2010. Material and methods: A descriptive study of the database of the national registry of HPN of NADYA-SENPE (December 10, 2009 to December 10, 2010). For the calculation of prevalence the latest data published by the Institute National Statistics Office (01/01/2009) was used. Results: There were registered 148 patients from 23 hospitals, 86 women (58.11%) and 9 children (6.08%). The average age of the 139 patients older than 14 years was 53.06 ± 15.41 years. The average duration of HPN was 316.97 days/patient. The most common diagnosis in those younger than 14 years was short bowel traumatic with 5 cases (55.55%) and in those older than 14 years, palliative care cancer with 29 cases (19.59%). The reason for the indication for HPN was short bowel syndrome in 74 cases (47%). The access via most frequently recorded was tunneled catheter in 36 cases (22.78%) followed by implanted port-catheters in 13 cases (8.23%) and other pathways in 3 cases (1.90%). There were 23 catheterrelated infections (82.14%) which represented 0.49 /1,000 days of PN, all of which occurred in cases older than 14 years. During the year 24 episodes of HPN ended, the most frequent cause was the transition to oral nutrition in 12 episodes (50%). It was reported that patients had a normal activity in 70 episodes of HPN (44.30%) with complete autonomy in 88 episodes (55.69%). Some patients 39 (24.68%) were potential candidates for intestinal transplantation. Conclusions: The number of registered patients is slightly lower than the previous year, although the number of participating hospitals is the same. The most frequent complication remains catheter-related infection but its incidence has decreased from previous years, presenting the lowest rate since the creation of the record. Differences in participation in the registry observed in the Autonomous Communities causes the development of implementation strategies. There is a gradual increase in day length of HPN over the years, which suggests the chronic treatments of some patients and obliges to study the existence of a possible confounding factor, in case there is an oversight of closing an episode. Therefore, it is necessary to update the registry with warning systems that facilitate periodic review of the patients and optimize the validity of registration.

Home parenteral nutrition registry in Spain for the year 2010: NADYA-SENPE Group

To report the Group Registry NADYASENPE data about home parenteral nutrition (HPN) in Spain in 2010. A descriptive study of the database of the national registry of HPN of NADYA-SENPE (December 10, 2009 to December 10, 2010). For the calculation of prevalence the latest data published by the Institute National Statistics Office (01/01/2009) was used. There were registered 148 patients from 23 hospitals, 86 women (58.11%) and 9 children (6.08%). The average age of the 139 patients older than 14 years was 53.06 ± 15.41 years. The average duration of HPN was 316.97 days/patient. The most common diagnosis in those younger than 14 years was short bowel traumatic with 5 cases (55.55%) and in those older than 14 years, palliative care cancer with 29 cases (19.59%). The reason for the indication for HPN was short bowel syndrome in 74 cases (47%). The access via most frequently recorded was tunneled catheter in 36 cases (22.78%) followed by implanted port-catheters in 13 cases (8.23%) and other pathways in 3 cases (1.90%). There were 23 catheterrelated infections (82.14%) which represented 0.49 /1,000 days of PN, all of which occurred in cases older than 14 years. During the year 24 episodes of HPN ended, the most frequent cause was the transition to oral nutrition in 12 episodes (50%). It was reported that patients had a normal activity in 70 episodes of HPN (44.30%) with complete autonomy in 88 episodes (55.69%). Some patients 39 (24.68%) were potential candidates for intestinal transplantation. The number of registered patients is slightly lower than the previous year, although the number of participating hospitals is the same. The most frequent complication remains catheter-related infection but its incidence has decreased from previous years, presenting the lowest rate since the creation of the record. Differences in participation in the registry observed in the Autonomous Communities causes the development of implementation strategies. There is a gradual increase in day length of HPN over the years, which suggests the chronic treatments of some patients and obliges to study the existence of a possible confounding factor, in case there is an oversight of closing an episode. Therefore, it is necessary to update the registry with warning systems that facilitate periodic review of the patients and optimize the validity of registration.

Sensitivity of CERES-Rice model to different environmental parameters on the productivity of aromatic rice in middle Gujarat

The present investigation was carried out during kharif season of 2007 and 2008 to develop genetic coefficients of four different genotypes of aromatic rice (cv. Pankhali, Narmada, GR-104 and Pusa Basmati-1) transplanted on three different dates viz., D1 (8th July), D2 (22nd July) and D3 (8th August). The sensitivity analysis of CERES-Rice model with respect to different scenarios of duration of photoperiods, solar radiation, CO2 concentration, maximum and minimum temperatures were carried out. The simulated grain yield increased linearly with incremental unit increase in day length, solar radiation, reduction of maximum temperature and vice versa. Simulated grain yields increased up to 27.9% under elevated scenarios of CO2 from 380 to 410 ppm by the model. Large yield reductions were observed on decreasing plant population. However, model did not show any significant change due to increase in the plant population. The model was found enough sensitive to account for the effects of transplant age of seedlings on simulated grain yield in comparison with the base yield.

Photoperiod History Differentially Impacts Reproduction and Immune Function in Adult Siberian Hamsters

Seasonal changes in numerous aspects of mammalian immune function arise as a result of the annual variation in environmental day length (photoperiod), but it is not known if absolute photoperiod or relative change in photoperiod drives these changes. This experiment tested the hypothesis that an individual's history of exposure to day length determines immune responses to ambiguous, intermediate-duration day lengths. Immunological (blood leukocytes, delayed-type hypersensitivity reactions [DTH]), reproductive, and adrenocortical responses were assessed in adult Siberian hamsters (Phodopus sungorus) that had been raised initially in categorically long (15-h light/day; 15L) or short (9L) photoperiods and were subsequently transferred to 1 of 7 cardinal experimental photoperiods between 9L and 15L, inclusive. Initial photoperiod history interacted with contemporary experimental photoperiods to determine reproductive responses: 11L, 12L, and 13L caused gonadal regression in hamsters previously exposed to 15L, but elicited growth in hamsters previously in 9L. In hamsters with a 15L photoperiod history, photoperiods < or = 11L elicited sustained enhancement of DTH responses, whereas in hamsters with a 9L photoperiod history, DTH responses were largely unaffected by increases in day length. Enhancement and suppression of blood leukocyte concentrations occurred at 13L in hamsters with photoperiod histories of 15L and 9L, respectively; however, prior exposure to 9L imparted marked hysteresis effects, which suppressed baseline leukocyte concentrations. Cortisol concentrations were only enhanced in 15L hamsters transferred to 9L and, in common with DTH, were unaffected by photoperiod treatments in hamsters with a 9L photoperiod history. Photoperiod history acquired in adulthood impacts immune responses to photoperiod, but manifests in a markedly dissimilar fashion as compared to the reproductive system. Prior photoperiod exposure has an enduring impact on the ability of the immune system to respond to subsequent changes in day length.