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Photoperiodic Response (photoperiodic + response)

Distribution by Scientific Domains

Life Sciences	92%

Selected Abstracts

THE CONTRIBUTION OF AN HOURGLASS TIMER TO THE EVOLUTION OF PHOTOPERIODIC RESPONSE IN THE PITCHER-PLANT MOSQUITO, WYEOMYIA SMITHII

EVOLUTION, Issue 10 2003
W. E. Bradshaw
Abstract Photoperiodism, the ability to assess the length of day or night, enables a diverse array of plants, birds, mammals, and arthropods to organize their development and reproduction in concert with the changing seasons in temperate climatic zones. For more than 60 years, the mechanism controlling photoperiodic response has been debated. Photoperiodism may be a simple interval timer, that is, an hourglasslike mechanism that literally measures the length of day or night or, alternatively, may be an overt expression of an underlying circadian oscillator. Herein, we test experimentally whether the rhythmic response in Wyeomyia smithii indicates a causal, necessary relationship between circadian rhythmicity and the evolutionary modification of photoperiodic response over the climatic gradient of North America, or may be explained by a simple interval timer. We show that a day-interval timer is sufficient to predict the photoperiodic response of W. smithii over this broad geographic range and conclude that rhythmic responses observed in classical circadian-based experiments alone cannot be used to infer a causal role for circadian rhythmicity in the evolution of photoperiodic time measurement. More importantly, we argue that the pursuit of circadian rhyth-micity as the central mechanism that measures the duration of night or day has distracted researchers from consideration of the interval-timing processes that may actually be the target of natural selection linking internal photoperiodic time measurement to the external seasonal environment. [source]

Effect of variation in photoperiodic response on diapause induction and developmental time in the willow leaf beetle, Plagiodera versicolora

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 1 2000
Michihiro Ishihara
Abstract The willow leaf beetle, Plagiodera versicolora (Coleoptera: Chrysomelidae) overwinters in adult diapause. In this study, the photoperiodic responses for diapause induction and developmental time were examined in the Ishikari (Hokkaido, Japan) population of P. versicolora. All females entered reproductive diapause under short daylength (L10:D14), but 31.7% of females did not enter diapause under long daylength (L16:D8). The developmental time from oviposition to adult emergence was significantly longer at L10:D14 than that at L16:D8. Norm of reaction curves illustrated variation among families in the photoperiodic responses for diapause induction and for developmental time. ANOVA indicated significant family × photoperiod interactions in the developmental time. At L16:D8, developmental time was positively correlated with the incidence of diapause in females. This means that a female having a longer developmental time tends to have a longer critical photoperiod. Such variation may be maintained by differences in selection pressures on the growth rate and the critical photoperiod for diapause induction between univoltine and bivoltine genotypes because Ishikari is located in a transitional area between populations with univoltine and bivoltine life cycles. [source]

THE CONTRIBUTION OF AN HOURGLASS TIMER TO THE EVOLUTION OF PHOTOPERIODIC RESPONSE IN THE PITCHER-PLANT MOSQUITO, WYEOMYIA SMITHII

Circadian rhythms and the evolution of photoperiodic timing in insects

PHYSIOLOGICAL ENTOMOLOGY, Issue 4 2009
DAVID S. SAUNDERS
Abstract. This review discusses possible evolutionary trends in insect photoperiodism, mainly from a chronobiological perspective. A crucial step was the forging of a link between the hormones regulating diapause and the systems of biological rhythms, circadian or circannual, which have independently evolved in eukaryotes to synchronize physiology and behaviour to the daily cycles of light and darkness. In many of these responses a central feature is that the circadian system resets to a constant phase at the beginning of the subjective night, and then ,measures' the duration of the next scotophase. In ,external coincidence', one version of such a clock, light now has a dual role. First, it serves to entrain the circadian system to the stream of pulses making up the light/dark cycle and, second, it regulates the nondiapause/diapause switch in development by illuminating/not illuminating a specific light sensitive phase falling at the end of the critical night length. Important work by A. D. Lees on the aphid Megoura viciae using so-called ,night interruption experiments' demonstrates that pulses falling early in the night lead to long-day effects that are reversible by a subsequent dark period longer than the critical night length and also show maximal sensitivity in the blue,green range of the spectrum. Pulses falling in the latter half of the night, however, produce long-day effects that are irreversible by a subsequent long-night and show a spectral sensitivity extending into the red. With movement to higher latitudes, insects develop genetic clines in various parameters, including critical night length, the number of long-night cycles needed for diapause induction, the strength of the response, and the ,depth' or intensity of the diapause thus induced. Evidence for these and other types of photoperiodic response suggests that they provided strong selective advantages for insect survival. [source]

Photoperiodic and temperature control of nymphal development and induction of reproductive diapause in two predatory Orius bugs: interspecific and geographic differences

PHYSIOLOGICAL ENTOMOLOGY, Issue 4 2008
DMITRY L. MUSOLIN
Abstract The effects of day-length and temperature on pre-adult growth and induction of reproductive diapause are studied in Orius sauteri and Orius minutus (Heteroptera: Anthocoridae) from northern (43.0°N, 141.4°E) and central (36.1°N, 140.1°E) Japan. In the north, at 20 °C, pre-adult growth is slower under an LD 14 : 10 h photoperiod than under shorter or longer photophases. At 24 and 28 °C, the longer photophases result in shorter pre-adult periods. Acceleration of nymphal growth by short days in autumn appears to be adaptive. In the central region, this response is less pronounced, suggesting that timing of adult emergence is less critical than in the north. Day length also influences the thermal requirements for pre-adult development. The slope of the regression line representing temperature dependence of pre-adult development is significantly smaller and the lower development threshold (LDT) is significantly lower under an LD 12 : 12 h photoperiod than under long-day conditions. The weaker dependence of nymphal growth on temperature and the lower LDT in autumn might be adaptive. In the north, increased temperature shifts the critical day length of diapause induction and suppresses the photoperiodic response in O. sauteri but not in O. minutus. Further south, the incidence of diapause in both species is low even under short-day conditions but the same interspecific difference is observed (i.e. increase of temperature affects the response in O. sauteri but not in O. minutus). This suggests seasonally earlier diapause induction with weaker temperature dependence in O. minutus than in O. sauteri. [source]

Photoperiod and temperature affect the life cycle of a subtropical cockroach, Opisoplatia orientalis: seasonal pattern shaped by winter mortality

PHYSIOLOGICAL ENTOMOLOGY, Issue 1 2004
Dao-Hong Zhu
Abstract.,Opisoplatia orientalis is an ovoviviparous cockroach living in the subtropical areas in Japan. Both adults and nymphs overwinter on Hachijo Island (33°N). The nymphs sampled before and after overwintering showed a similar pattern in frequency distribution of head widths with a definite peak of fifth instars. The present study was conducted to determine how this pattern was formed by investigating the effects of photoperiod and temperature on development and reproduction. Photoperiod influenced the number of nymphal instars, resulting in a longer duration of nymphal development at LD 12 : 12 h than at LD 16 : 8 h. However, the rate of development at each instar was only affected to a small extent by photoperiod and no sign of diapause was detected. It was suggested that the photoperiodic response controlling the number of nymphal instars might have evolved to adjust the timing of adult emergence and reproduction to the favourable season. The prereproductive period and time intervals between nymph depositions were prolonged as temperature declined, but there was no evidence for diapause in adults. Mortality occurred in eggs and embryos inside of the body of the females during winter. Thus, it was inferred that female adults would reset ovarian development in spring and deposit nymphs in summer simultaneously, and these nymphs would reach the fifth instar before winter comes. This winter mortality hypothesis was supported by experiments in which reproductive activity and mortality were monitored for field-collected adults under either constant or changing temperature conditions simulating those in the field. [source]

Photoperiodic and temperature control of diapause induction and colour change in the southern green stink bug Nezara viridula

PHYSIOLOGICAL ENTOMOLOGY, Issue 2 2003
Dmitry L. Musolin
Abstract. The effect of photoperiod and temperature on the duration of the nymphal period, diapause induction and colour change in adults of Nezara viridula (L.) (Heteroptera: Pentatomidae) from Japan was studied in the laboratory. At 20 °C, the developmental period for nymphs was significantly shorter under LD 10 : 14 h (short day) and LD 16 : 8 h (long day) than under intermediate photoperiods, whereas at 25 °C it was slightly shorter under intermediate than short- and long-day conditions. It is assumed that photoperiod-mediated acceleration of nymphal growth takes place in autumn when day-length is short and it is unlikely that nymphal development is affected by day-length under summer long-day and hot conditions. Nezara viridula has an adult diapause controlled by a long-day photoperiodic response. At 20 °C and 25 °C in both sexes, photoperiodic responses were similar and had thresholds close to 12.5 h, thus suggesting that the response is thermostable within this range of temperatures and day-length plays a leading role in diapause induction. Precopulation and preoviposition periods were significantly longer under near-critical regimes than under long-day ones. Short-day and near-critical photoperiods induced a gradual change of adult colour from green to brown/russet. The rate of colour change was significantly higher under LD 10 : 14 h than under LD 13 : 11 h, suggesting that the colour change is strongly associated with diapause induction. The incidences of diapause or dark colour did not vary among genetically determined colour morphs, indicating that these morphs have a similar tendency to enter diapause and change colour in response to short-day conditions. [source]

Phytochromes confer the photoperiodic control of flowering in rice (a short-day plant)

THE PLANT JOURNAL, Issue 5 2000
Takeshi Izawa
Summary The photoperiodic sensitivity 5 (se5) mutant of rice, a short-day plant, has a very early flowering phenotype and is completely deficient in photoperiodic response. We have cloned the SE5 gene by candidate cloning and demonstrated that it encodes a putative heme oxygenase. Lack of responses of coleoptile elongation by light pulses and photoreversible phytochromes in crude extracts of se5 indicate that SE5 may function in phytochrome chromophore biosynthesis. Ectopic expression of SE5 cDNA by the CaMV 35S promoter restored the photoperiodic response in the se5 mutant. Our results indicate that phytochromes confer the photoperiodic control of flowering in rice. Comparison of se5 with hy1, a counterpart mutant of Arabidopsis, suggests distinct roles of phytochromes in the photoperiodic control of flowering in these two species. [source]

Red jungle fowl (Gallus gallus) as a model for studying the molecular mechanism of seasonal reproduction

ANIMAL SCIENCE JOURNAL, Issue 3 2009
Hiroko ONO
ABSTRACT Photoperiodism is an adaptation mechanism that enables animals to predict seasonal changes in the environment. Japanese quail is the best model organism for studying photoperiodism. Although the recent availability of chicken genome sequences has permitted the expansion from single gene to genome-wide transcriptional analysis in this organism, the photoperiodic response of the domestic chicken is less robust than that of the quail. Therefore, in the present study, we examined the photoperiodic response of the red jungle fowl (Gallus gallus), a predecessor of the domestic chicken, to test whether this animal could be developed as an ideal model for studying the molecular mechanisms of seasonal reproduction. When red jungle fowls were transferred from short-day- to long-day conditions, gonadal development and an increase in plasma LH concentration were observed. Furthermore, rapid induction of thyrotropin beta subunit, a master regulator of photoperiodism, was observed at 16 h after dawn on the first long day. In addition, the long-day condition induced the expression of type 2 deiodinase, the key output gene of photoperiodism. These results were consistent with the results obtained in quail and suggest that the red jungle fowl could be an ideal model animal for the genome-wide transcriptional analysis of photoperiodism. [source]

Oral thyroxine administration mimics photoperiodically induced gonadal growth in Japanese quail

ANIMAL SCIENCE JOURNAL, Issue 5 2004
Shinobu YASUO
ABSTRACT Most temperate-zone animals are seasonal breeders. In a previous study, it was found that light-induced hormone conversion of thyroxine (T4) prohormone to active 3,5,3,-triiodothyronine (T3) in the mediobasal hypothalamus regulates photoperiodic response of gonads in Japanese quail. Here the effect of T4 or T3, administered in drinking water, on testicular growth in the Japanese quail kept under short days is shown. Testicular length was significantly increased in birds given T4 at doses of 4, 8 and 10 mg/L, while any dose of T3 had little effect on testicular growth. High doses (8 and 10 mg/L) of T4 and T3 resulted in high mortality and/or reduction of bodyweight. Among all of the treatment, 4 mg/L of T4 was the most effective on photoperiodic testicular growth, which caused little reduction in bodyweight. These data provide a new conventional method for promoting gonadal growth under short days. [source]

Effect of variation in photoperiodic response on diapause induction and developmental time in the willow leaf beetle, Plagiodera versicolora

Changes in Basal Hypothalamic Chicken Gonadotropin-Releasing Hormone-I and Vasoactive Intestinal Polypeptide Associated with a Photo-Induced Cycle in Gonadal Maturation and Prolactin Secretion in Intact and Thyroidectomized Starlings (Sturnus vulgaris)

JOURNAL OF NEUROENDOCRINOLOGY, Issue 7 2002
A. Dawson
Abstract Chicken gonadotropin-releasing hormone-I (GnRH-I) and the avian prolactin-releasing hormone, vasoactive intestinal polypeptide (VIP), were measured in the basal hypothalamus in male starlings during photo-induced gonadal growth and the subsequent development and maintenance of reproductive photorefractoriness. Comparisons were made with thyroidectomized birds, which maintain breeding condition irrespective of changes in photoperiod. In intact birds, basal hypothalamic GnRH-I increased four-fold after photostimulation and then decreased 115-fold over 12 weeks to values characteristic of long-term photorefractoriness. Pituitary and plasma prolactin increased after photostimulation, reaching peak values when the testes were regressing, and returned to low values in long-term photorefractory birds. Basal hypothalamic VIP did not change after photostimulation in intact birds. In photostimulated thyroidectomized birds, values for basal hypothalamic GnRH-I and VIP, and for pituitary and plasma prolactin, remained no different to those of nonphotostimulated intact birds. These observations confirm that reproductive photorefractoriness is related to a decrease in hypothalamic GnRH-I. However, photorefractoriness in terms of prolactin secretion is not similarly related to a decrease in basal hypothalamic VIP. The mechanisms responsible for the decrease in prolactin in long-term photorefractory birds and for the total lack of photoperiodic responses in thyroidectomized birds remain unresolved. [source]