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29182. Photoperiod, diapause and cold-hardiness
- Creator:
- Hodkova, Magdalena and Hodek, Ivo
- Type:
- article, model:article, and TEXT
- Subject:
- Photoperiod, temperature, diapause, cold-hardiness, hormones, survival, supercooling, cryoprotectants, and Pyrrhocoris apterus
- Language:
- English
- Description:
- Great progress has recently been made in cryobiology. One field, however, has been neglected: the temporal sequence of the effects of photoperiod and temperature, and their relative importance in cold hardening. This is relevant to the question of importance of diapause in cold-hardiness. Denlinger (1991) outlined the categories of such relations and stressed a great need for further detailed research. A survey of studies done over the past decade revealed many gaps in the evidence and the ambiguous nature of the data on the photoperiodic regulation of cold-hardiness. We hope that this review will stimulate further research in this field. Among several directions where research is most needed we have stressed (1) simultaneous recording of changes in survival and dynamics of suspected cryoprotectants (stressed also by Danks, 1996), (2) checking the regulation of different phases of cold hardening, and (3) discrimination between direct and indirect (mediated via neuroendocrine system) effects of environmental cues on cold hardening.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
29183. Photoperiodic clock of diapause termination in Pseudopidorus fasciata (Lepidoptera: Zygaenidae)
- Creator:
- Li, Aiqing, Xue, Fangsen, Hua, Ai, and Tang, Jianjun
- Type:
- article, model:article, and TEXT
- Subject:
- Pseudopidorus fasciata, photoperiod, diapause termination, and hourglass
- Language:
- English
- Description:
- Photoperiodic control of diapause termination was systematically investigated in Pseudopidorus fasciata. In 24 h light-dark cycles, the rate of diapause termination in this species depended on photoperiod. The critical night length (CNL) for diapause termination was 10 h, 0.5 h shorter than that for diapause induction. Night-interruption experiments with T = 24 showed that diapause was effectively terminated when the scotophases separated by light pulse were shorter than the critical night length (10 h); no developing individuals were found if the duration of the pre-interruption scotophase or the post-interruption scotophase exceeded the CNL. A 15-min light pulse was sufficient to reverse the effect of long night when it was placed 8 h after lights-off. Resonance experiments with a constant photophase of 12 h or 16 h and various scotophases of 4-80 h showed an hourglass-type photoperiodic response, where no rhythmicity was found. In another resonance experiment with constant scotophase of 8 h and various photophases of 4-72 h, all individuals developed into cocoons. In the Bünsow experiment, the response curve showed two apparent peaks for diapause termination, one being 8 h after lights-off, and another 8 h before lights-on. However, there was no periodic rhythmicity, which again indicates an hourglass principle. The results lead to the conclusion that the same photoperiodic clock mechanism (a long-night measuring hourglass) is involved in both diapause induction and termination.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
29184. Photoperiodic control of development and reproduction in Harmonia axyridis (Coleoptera: Coccinellidae)
- Creator:
- Reznik, Sergey Ya. and Vaghina, Nina P.
- Type:
- article, články, model:article, and TEXT
- Subject:
- Zoologie, entomologie, Coccinellidae, Harmonia axyridis, photoperiod, development, maturation, diapause, phenology, 2, and 59
- Language:
- English
- Description:
- The effects of photoperiod on pre-imaginal development and reproductive maturation of adult females of the multicolored Asian lady beetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), were investigated at 20°C and at photoperiods from 10L : 14D to 18L : 6D. Experiments were conducted on a laboratory strain that originated from the Russian Far East. Larvae and adults were fed on the green peach aphid Myzus persicae. Under short day conditions the pre-imaginal development was faster than under long day conditions. The acceleration of pre-imaginal development occurred when day length was shorter than 16 h and the threshold day length was ca 14 h. The rate of reproductive maturation of adult females, in contrast, was twice as high under long day conditions, with the threshold between 14L : 10D and 12L : 12D, although even under short day conditions ca 10% of the females show a tendency to mature more quickly. This difference between the thresholds of these two photoperiodic reactions indicates they are relatively independent of one another. and Sergey Ya. Reznik, Nina P. Vaghina.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
29185. Photoperiodic control of the intensity of diapause and diapause development in the bean bug, Riptortus clavatus (Heteroptera: Alydidae)
- Creator:
- Nakamura , Keiji and Numata, Hideharu
- Type:
- article, model:article, and TEXT
- Subject:
- Heteroptera, Riptortus clavatus, adult diapause, diapause intensity, diapause development, and photoperiod
- Language:
- English
- Description:
- Adult diapause in Riptortus clavatus (Thunberg) was induced by short-day photoperiods, and the critical daylength for its induction was 13.5 h. When insects were reared from eggs under diapause-inducing photoperiods near the critical daylength, the duration of diapause was shorter than when reared under the shorter daylengths. Adults terminated diapause under long-day photoperiods earlier when they had been raised under a near-critical photoperiod than under shorter daylengths; this indicated that the initial intensity of diapause was dependent on the length of the inducing photoperiod. Not only the photoperiods experienced during preimaginal development but also the value of the long-day photoperiods experienced after adult emergence affected the time of onset of oviposition. When the photophase was shortened, either abruptly or gradually after adult emergence, the duration of diapause was prolonged. Diapause was long when induced by shorter daylengths than the near-critical photoperiod. Different photoperiods have thus different quantitative effects on both the initial intensity of diapause and the rate of diapause development.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
29186. Photoperiodic induction and termination of summer diapause in adult Epilachna admirabilis (Coleoptera: Coccinellidae) from a warm temperate region
- Creator:
- Imai, Chobei
- Type:
- article, model:article, and TEXT
- Subject:
- Adult summer diapause, Coccinellidae, diapause development, Epilachna admirabilis, intermediate photoperiodism, latitudinal difference, recurrent photoperiodic response, reproductive diapause, and reversible response
- Language:
- English
- Description:
- In warm temperate and subtropical regions an adult summer diapause regulates the timing of oviposition. Epilachna admirabilis is a univoltine phytophagous lady beetle ranging from south to north Japan, Taiwan, China and Myanmar. In Japan the species hibernates in the full-grown larval stage. In cool temperate Sapporo (43°04´N) the adults never enter summer diapause but pass a second winter in diapause. This study revealed that in Kyoto (35°01´N), the adults had a summer diapause induced by an intermediate photoperiodic response; they had a critical photoperiod of approximately 14.5 h light per day. All females entered reproductive diapause under a long photoperiod of 16L (light) : 8D (dark) and 6.7% of them did so under shorter photoperiods of 13L : 11D and 12L : 12D. However, diapause incidence was 40% at 8L : 16D, suggesting the existence of a second critical photoperiod at a photophase slightly less than 8 h. At photophases of 12-15 h, non-diapausing females laid eggs on average between 27.1 to 39.0 days after emergence. Photoperiod reversibly regulated the induction, maintenance and termination of the adult diapause. Temperatures of 20-30°C did not affect the incidence and termination of diapause at 16L : 8D. Adult winter diapause at the higher latitude Sapporo might have originated from adult summer diapause at middle latitude regions such as Kyoto. Selection at increasing latitudes would have forced northerly populations of the species to lose the adult summer diapause in the range of natural day-lengths. Subsequent selection pressure should have favored adults that avoided futile oviposition in late summer or autumn, survived cold winters in diapause and commenced an additional oviposition in the second summer. Thus, a latitudinal difference in photoperiodic responses might have developed.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
29187. Photoperiodic receptor in the nymph of Poecilocoris lewisi (Heteroptera: Scutelleridae)
- Creator:
- Miyawaki, Ryo, Tanaka, Shinichi I., and Numata, Hideharu
- Type:
- article, model:article, and TEXT
- Subject:
- Photoreceptor, photoperiodism, compound eye, nymphal diapause, and Poecilocoris lewisi
- Language:
- English
- Description:
- The receptor for photoperiodism in nymphs of Poecilocoris lewisi was examined using a phosphorescent paint, which absorbs light energy and emits phosphorescence in the dark. This species shows a facultative diapause in the fifth (final) nymphal instar and its induction is primarily controlled by photoperiod in the fourth instar. The incidence of diapause in the fifth instar was determined after exposing selected regions of the body surface to a longer photophase than the rest by applying a phosphorescent paint in the fourth instar. The incidence of diapause was significantly lower in insects with their compound eyes painted than in control insects at near-critical daylengths. However, painting the central part of the head had no effect. It is concluded, therefore, that the compound eyes are the principal receptor for photoperiodism in nymphs of P. lewisi. This is the first report implicating the compound eyes in the reception of photoperiod in nymphal insects.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
29188. Photoperiodic regulation of PER1 and PER2 protein expression in rat peripheral tissues
- Creator:
- Bendová, Z. and Sumová, A.
- Type:
- article, model:article, and TEXT
- Subject:
- Circadian rhythms, Peripheral tissue, PER proteins, and Rat
- Language:
- English
- Description:
- Circadian oscillations in biological variables in mammals are controlled by a central pacemaker in the suprachiasmatic nuclei (SCN) of the hypothalamus which coordinates circadian oscillators in peripheral tissues. The molecular clockwork responsible for this rhythmicity consists of several clock genes and their corresponding proteins that compose interactive feedback loops. In the SCN, two of the genes, Per1 and Per2, show circadian rhythmicity in their expression and protein production. This SCN rhythmicity is modified by the length of daylight, i.e. the photoperiod. The aim of the present study was to find out whether profiles of PER1 and PER2 proteins in peripheral organs are also affected by the photoperiod. Rats were maintained under a long photoperiod with 16 h of light and 8 h of darkness per day (LD 16:8) and under a short, LD 8:16, photoperiod. The PER1 and PER2 daily profiles were measured in peripheral organs by Western blotting. The photoperiod affected significantly the PER1 profile in livers and the PER2 profile in lungs and hearts. In lungs, PER2 in the cytoplasmic, but not in the nuclear fraction, was affected significantly. The effect of the photoperiod on PER1 profiles in peripheral organs appears to differ from that in the SCN.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
29189. Photoperiodism and seasonal adaptations in some seed-sucking bugs (Heteroptera) in central Japan
- Creator:
- Numata, Hideharu and Nakamura, Keiji
- Type:
- article, model:article, and TEXT
- Subject:
- Photoperiodic response, critical daylength, adult diapause, seed-sucking bugs, Heteroptera, Pentatomidae, and Alydidae
- Language:
- English
- Description:
- Photoperiodic responses and their adaptive significance were examined in Riptortus clavatus (Heteroptera: Alydidae), Plautia crossota stali, Dolycoris baccarum, Aelia fieberi, Nezara viridula, Nezara antennata, Graphosoma rubrolineatum, Dybowskyia reticulata, and Eurydema rugosum (Heteroptera: Pentatomidae) in the Kyoto-Osaka area, central Japan. All of these species overwinter as adults in diapause. Although they have similar feeding habits, their photoperiodic responses were quite different. Riptortus clavatus, P. c. stali, D. baccarum and N. viridula showed long-day photoperiodic responses with critical daylengths between 13 and 14 h, and were assumed to have three generations per year. The photoperiodic responses of the other five species were different both from those of the above species and from each other. These results suggested that A. fieberi and N. antennata produce two generations per year, and G. rubrolineatum, D. reticulata and E. rugosum have one or two generations per year. Nezara antennata showed a long-day-short-day photoperiodic response with summer adult diapause, which may avoid production of heat-susceptible nymphs in the hottest season. With the exception of N. antennata, the photoperiodic responses resulting in fewer generations were shown to be adaptations to dietary conditions in the field.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
29190. Phototoxic activity and the possibilities of its testing
- Creator:
- Chobot, V.
- Type:
- model:article and TEXT
- Language:
- English
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public