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P. M. Brakefield F. Kesbeke 《Proceedings. Biological sciences / The Royal Society》1997,264(1382):717-723
Experiments on life history genetics are usually performed using constant temperature environments in the laboratory. However, the dynamics of insect growth can be influenced profoundly by daily fluctuations in temperature such as those which characterize field environments. We report here on experiments using different stocks and selected lines of a tropical butterfly, Bicyclus anynana, to examine whether genotype-environment interactions occur for three traits describing pre-adult growth. These traits were measured over two pairs of environments differing in mean temperature, each of which had a constant, and a cycling temperature regime. Development time, pupal weight and growth rate show genotype-environment interactions, especially at comparatively low average temperatures. Researchers should, therefore, take care when extrapolating from the form of genetic covariance matrices and ''trade-offs'' among life history traits found in constant temperature environments to those likely to occur in nature. <br> 相似文献
2.
The effects of thermo- and photoperiodicity on elongation growth and on endogenous level of gibberellins (GAs) in Begonia x hiemalis during various phases of the day-night cycle have been studied. Plant tissue was harvested during the day and night cycle
after temperature and photoperiodic treatments and analyzed for endogenous GAs using combined gas chromatography and mass
spectrometry. Elongation growth increased when the difference between day and night temperature (DIF = DT − NT) increased
from a negative value (−9.0 and −4.5°C) to zero and with increasing photoperiod from 8 to 16 h. When applied to the youngest
apical leaf, gibberellins A1, A4, and A9 increased the elongation of internodes and petioles. GA4 had a stronger effect on elongation growth than GA1 and GA9. In relative values, the effect of these GAs decreased when DIF increased from −9 to 0°C. The time of applying the GAs during
a day and night cycle had no effect on the growth responses. In general, endogenous levels of GA19 and GA20 were higher under negative DIF compared with zero DIF. The level of endogenous GA1 in short day (SD)-grown plants was higher under zero DIF than under negative DIF, but this relationship did not appear in
long day (LD)-grown plants. The main effects of photoperiod seem to be a higher level of GA19 and GA1 at SD compared with LD, whereas GA20 and GA9 show the opposite response to photoperiod. No significant differences in endogenous level of GA1, GA9, GA19, and GA20 were found for various time points during the diurnal day and night cycle. Endogenous GA20 was higher in petiole and leaf compared with stem, whereas there were no differences of GA1, GA9, and GA19 between plant parts. No clear relationship was found between elongation of internodes and petioles and levels of endogenous
GAs.
Received December 26 1996; accepted July 1, 1997 相似文献
3.
Watari Y 《Journal of insect physiology》2002,48(9):881-886
When non-diapause and diapause pupae of Deliaantiqua were exposed to various thermoperiods where thermophase (T) was 25 °C and the cryophase (C) was 15 or 20 °C (TC15 or TC20) in constant darkness (DD), the majority of both types of flies emerged before the rise in temperature. Eclosion time was delayed at the lower cryophase temperature. Moreover, there was a significant difference in the time of adult eclosion between non-diapause and diapause pupae; diapause pupae eclosed earlier than non-diapause pupae. When the two types of pupae were transferred to a constant low temperature (15 or 20 °C) after having experienced TC15 or TC20 12:12 h, they showed circadian rhythmicity in eclosion. The free-running period (τ) of the eclosion rhythm changed after transfer to constant low temperatures in both non-diapause and diapause pupae, suggesting that this change represents a transient cycle until the temperature-sensitive oscillator is coupled again to the temperature-insensitive pacemaker. However, diapause pupae tended to show a shorter τ than non-diapause pupae. This observation suggests that the difference in adult eclosion time under thermoperiodic conditions between non-diapause and diapause pupae is related to their different τ s. 相似文献
4.
SHIGERU KIKUKAWA RYOU HASHIZUME MIHO HONDA YUKA INOUE TATSUYA MAEKAWA RISA SAKATA NANAKO TAKAHASHI KUNIAKI TANAKA YU UCHIDA 《Physiological Entomology》2013,38(3):253-259
In addition to photoperiod, thermoperiod (or thermocycle) might be an important Zeitgeber for entraining the circadian oscillator controlling adult eclosion rhythm in the Indian meal moth Plodia interpunctella Hübner (Lepidoptera: Pyralidae). This is confirmed by exposing larvae receiving diapause‐preventing treatments to various thermocycles with different means and amplitudes of temperature. The thermocycles investigated in the present study are TC 8 : 16 h, TC 12 : 12 h, TC 16 : 8 h and TC 20 : 4 h, where T and C represent thermophase (30 °C) and cryophase (20 °C), respectively. For all thermocycles, the peak of adult eclosion rhythm occurs at around the mid‐thermophase. This indicates that the larvae use both ‘temperature‐rise’ and ‘temperature‐fall’ signals to adjust the eclosion phase in each thermocycle. The absence (DD) or presence (LL) of light affects this time‐keeping system slightly under the given thermocycle. The rhythmic adult eclosion noted after exposure of larvae to 30 °C DD for 14 days is recorded in the thermocycles (TC 12 : 12 h, DD; mean temperature = 25 °C) with different amplitudes of 27.5/22.5 °C, 26.5/23.5 °C and 25.5/24.5 °C. The peak in adult eclosion advances in time as the amplitude of the temperature cycle decreases. In the temperature cycle of 25.5/24.5 °C, a peak occurs at the end of the cryophase, 2 h before the temperature‐rise. The adult eclosion rhythm is also observed under various thermocycles (TC 12 : 12 h, DD) consisting of different temperature levels (30 to 20 °C) with different amplitudes. It is found that the temporal position of the peak advances significantly when the amplitude of the thermocycle becomes lower. 相似文献
5.
Thermoperiodic regulation of the circadian eclosion rhythm in the flesh fly, Sarcophaga crassipalpis
We recorded the eclosion time of the flesh fly, Sarcophaga crassipalpis, at different depths in the outdoor soil and under temperature cycles with various amplitudes in the laboratory, to examine the timing adjustment of eclosion in response to temperature cycles and their amplitudes in the pupal stage. In the soil, most eclosions occurred in the late morning, which was consistent with the eclosion time under pseudo-sinusoidal temperature cycles in the laboratory. The circadian clock controlling eclosion was reset by temperature cycles and free-ran with a period close to 24 h. This clock likely helps pupae eclose at an optimal time even when the soil temperature does not show clear daily fluctuations. The eclosion phase of the circadian clock progressively advanced as the amplitude of the pseudo-sinusoidal temperature cycle decreased. This response allows pupae located at any depth in the soil to eclose at the appropriate time despite the depth-dependent phase delay of the temperature change. In contrast, the abrupt temperature increase in square-wave temperature cycles reset the phase of the circadian clock to the increasing time, regardless of the temperature amplitude. The rapid temperature increase may act as the late-morning signal for the eclosion clock. 相似文献
6.
Thermoperiodic acclimations enhance cold hardiness of the eggs of the migratory locust 总被引:2,自引:0,他引:2
Treatment of thermoperiods that simulate the patterns of natural occurrence is most efficient in enhancing cold hardiness. To examine the effects of different thermoperiods on cold hardiness of eggs in the migratory locust, Locusta migratoria (L.), the survival rates, cryoprotectant levels and three hsps expressions in mid-stage eggs (7-day-old) were measured after the eggs were subjected to three different thermoperiod regimes, : short (2 day), long (10 day), and nature-mimicking thermoperiodic acclimation. The thermoperiodic acclimations resulted in the highest egg survival rates in both the short and the long period acclimation groups in comparison with the groups treated with constant temperatures. The egg survival of nature-mimicking thermoperiod groups was significantly higher than those of constant temperature groups for the same acclimation duration. The survival rate of eggs under single daily thermoperiod was higher than that of multiple daily thermoperiods. The concentration of cryoprotectants (myo-inositol, trehalose, mannitol and sorbitol) and the expression levels of hsp20.5, hsp70, and hsp90 all increased in thermoperiodic acclimation eggs. 相似文献
7.
In the spider mite Tetranychus urticae photoperiodic time measurement proceeds accurately in orange-red light of 580 nm and above in light/dark cycles with a period length of 20 h but not in 'natural' cycles with a period length of 24 h. To explain these results it is hypothesized that the photoperiodic clock in the spider mite is sensitive to orange-red light, but the Nanda-Hamner rhythm (a circadian rhythm with a free-running period tau of 20 h involved in the photoperiodic response) is not and consequently free runs in orange-red light. To test this hypothesis a zeitgeber was sought that could entrain the Nanda-Hamner rhythm to a 24-h cycle without inducing diapause itself, in order to manipulate the rhythm independently from the orange-red sensitive photoperiodic clock. A suitable zeitgeber was found to be a thermoperiod with a 12-h warm phase and a 12-h cold phase. Combining the thermoperiod with the long-night orange-red light/dark regime, both with a cycle length of 24 h, resulted in a high diapause incidence, although neither regime was capable of inducing diapause on its own. The conclusion is that the Nanda-Hamner rhythm is necessary for the realization of the photoperiodic response, but is not part of the photoperiodic clock, because photoperiodic time measurement takes place in orange-red light whereas the rhythm is not able to 'see' the orange-red light. It is speculated that the Nanda-Hamner rhythm is involved in the timely synthesis of a substrate for the photoperiodic clock in the spider mite. 相似文献
8.
The present study showed that the eggs of the desert locust, Schistocerca gregaria, and the migratory locust, Locusta migratoria, responded to photoperiod by hatching when placed on sand in the laboratory. S. gregaria mainly hatched during the dark phase and L. migratoria during the light phase. The importance of light as a hatching cue depended on the magnitude of the temperature change during the thermoperiod; photoperiod played a more important role in the control of hatching time in both species when the magnitude of the temperature change was small. In addition, the eggs of the two species that were covered with sand did not respond to photoperiod and hatched during both the light and dark phases, indicating that light did not penetrate through the sand. Because locust eggs are normally laid as egg pods and a foam plug is deposited between the egg mass and the ground surface, we tested a possibility that naturally deposited eggs perceived light through the foam plug. The eggs that were deposited and left undisturbed in the sand hatched during the light and dark phases at similar frequencies. These results suggest that the eggs of both locust species responded to light and controlled their hatching timing accordingly but would not use light as a hatching cue in the field. The evolutionary significance of the ability of eggs to respond to light in these locusts was discussed. 相似文献
9.
T. J. J. Tsafack Gilbert P. Charles A. Hourmant N. D. Omokolo M. Branchard 《Plant Cell, Tissue and Organ Culture》2009,96(2):151-159
Cocoyam (Xanthosoma sagittifolium L. Schott) is an important staple tuber crop for tropic populations and consists of three cultivars with different productivity.
In vitro tuber induction of a broad range of genotypes could be a very useful way to propagate and increase valuable cocoyam.
Shoot tips were cultured on a multiplication medium containing MS mineral salts, Morel and Wetmore (Ann J Bot 38:141–143,
1951) vitamins, 3% sucrose and 6% agar. Multiple shoots induced with 6-benzylaminopurine (BAP) were allowed to develop on the
basal medium without plant growth regulators (PGRs). The subsequent explants obtained were used for the production of microtubers
on MS-based PGRs free medium supplemented with 8% sucrose. Microtuberization was evaluated after 60 days of culture under
different photo- and thermoperiod regimes. Changes in carbohydrates were also examined enzymatically during this process.
Microtuberization response of three cocoyam cultivars (White, Red and Yellow) was influenced by photoperiod and thermoperiod
regimes. A short photoperiod (8 h lighting), combined with an application of a day/night temperature regime 25/20°C for 10 days,
followed by a continuous darkness at 20°C for 50 days, was the most effective treatment. The best response was observed with
White followed by Red and Yellow cultivar. The sprouting frequency of microtubers varied significantly with cvs. after 15 days
of culture (56% for White, 50% for Red and 40% for Yellow). Under tuber promoting condition, the onset of the process was
characterized by an accumulation of starch and hexoses in leaves. The glucose:fructose ratio changed in favour of glucose
earlier in White cultivar leaves where it doubled in 10 days. Moreover, in young developing tubers, the sucrose content increased
concomitantly with starch. 相似文献
10.
Timing of circadian activities is controlled by rhythmic expression of clock genes in pacemaker neurons in the insect brain. Circadian behavior and clock gene expression can entrain to both thermoperiod and photoperiod but the availability of such cues, the organization of the brain, and the need for circadian behavior change dramatically during the course of insect metamorphosis. We asked whether photoperiod or thermoperiod entrains the clock during pupal and pharate adult stages by exposing flies to different combinations of thermoperiod and photoperiod and observing the effect on the timing of adult eclosion. This study used qRT-PCR to examine how entrainment and expression of circadian clock genes change during the course of development in the flesh fly, Sarcophaga crassipalpis. Thermoperiod entrains expression of period and controls the timing of adult eclosion, suggesting that the clock gene period may be upstream of the eclosion pathway. Rhythmic clock gene expression is evident in larvae, appears to cease during the early pharate adult stage, and resumes again by the time of adult eclosion. Our results indicate that both patterns of clock gene expression and the cues to which the clock entrains are dynamic and respond to different environmental signals at different developmental stages in S. crassipalpis. 相似文献
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