• Molecules and Cells
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• 제39권10호
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• pp.715-721
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• 2016

Plants have become physiologically adapted to a seasonally shifting environment by evolving many sensory mechanisms. Seasonal flowering is a good example of adaptation to local environmental demands and is crucial for maximizing reproductive fitness. Photoperiod and temperature are major environmental stimuli that control flowering through expression of a floral inducer, FLOWERING LOCUS T (FT) protein. Recent discoveries made using the model plant Arabidopsis thaliana have shown that the functions of photoreceptors are essential for the timing of FT gene induction, via modulation of the transcriptional activator CONSTANS (CO) at transcriptional and post-translational levels in response to seasonal variations. The activation of FT transcription by the fine-tuned CO protein enables plants to switch from vegetative growth to flowering under inductive environmental conditions. The present review briefly summarizes our current understanding of the molecular mechanisms by which the information of environmental stimuli is sensed and transduced to trigger FT induction in leaves.

• 한국응용곤충학회지
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• 제29권2호
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• pp.123-131
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• 1990

숫검 은밤나방(Agrotis tokionis Butler) 유충 하면의 개시와 종료에 온도와 광주기가 어떠한 역할을 하는지 조사하였다. 자연조건에서 하면기간은 유충이 하면을 시작하는 시기가 늦을수록 짧아져서 조사짐단내 용화시기는 일치하는 경향을 보였다. 실험한 모든 광주기 및 온도 조건에서 유충의 발육속도에는 변화가 있었으나 하면개시에는 아무런 영향을 미치지 못하 였기 때문에 이 곤충의 하면은 내인성으로 추측되었다. 그러나 하면의 종료는 이상의 두가 지 환경조건의 변화에 영향을 받았다. 온도조건에 대한 반응에 따라 하면기간은 2시기로 나눌 수 있었는데 전기에는 평균온도가 높을수록 하면시간이 단축되었으나 후기에는 저온 일수록 짧아졌다. 또한 실험한 광주기에서는 단일조건 (LD 8 : 16)에서 하면기간이 가장 짧았다.

• International Journal of Industrial Entomology and Biomaterials
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• 제15권1호
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• pp.1-7
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• 2007

At present, multivoltine silkworm races reared five times per year involving huge manpower and rearing expenditure. Egg diapausing behavior is facultative in multivoltine and egg diapause was induced in selected multivoltine races by regulating temperature at $18^{\circ}C$, relative humidity 80% and photoperiod (6L:18D) in the late stage silkworm rearing. The maximum percentage of egg diapause induction was recorded in Rong Diazo, Diazo and MW13 showed 94%, 93% and 92% respectively, whereas the races A14DY and OS-616 showed minimum diapause induction 15% and 18% respectively. The diapause induced multivoltine eggs were preserved up to six months by cold preservation schedule normally adopted for bivoltine. After three and six months egg preservation, the diapause induced layings were released and observed for hatching percentage, all races showed above 82 % of hatching except the race AP12, which showed only 78 % of hatching. This methods reduce the crop cycle, gives strong safety backup and preventing the genetic erosion. This study helps formulating a new conservation method for multivoltine silkworm germplasm.

• Journal of Photoscience
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• 제9권2호
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• pp.252-254
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• 2002

Djungarian hamsters show distinct seasonal rhythms in several physiological parameters. One of them is daily torpor that occurs in winter with decreased body temperature (about 1O-20$^{\circ}$C) during daytime. Daily torpor is induced by short-day photoperiod, food restriction and castration. But the mechanism to induce daily torpor has not been clarified. In the present study, we tried to clarify the process of daily torpor induction in detail. Adult male hamsters were kept in long photoperiod and high temperature (LP-HT) before the experiment and, thereafter, the animals were transferred to short photoperiod and low temperature (SP-LT), and they were kept in this condition for about six months. The daily rhythms of locomotor activity and body temperature were recorded every three-minutes by using the Minimitter telemetry system. Locomotor activity and body temperature showed very closely synchronized rhythms. All animals under LP-HT showed daily rhythms with higher locomotor activity and body temperature in nighttime than in daytime. Under SP-LT, there were two types of animals with and without showing daily torpor. Thus, they have individual differences in the response to SP -LT.

• 한국수산과학회지
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• 제41권5호
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• pp.381-388
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• 2008

Induction of regeneration and maturation for the free-living gametophytes of Ecklonia cava Kjellman was conducted under various temperature, irradiance and photoperiod conditions. Culture conditions for female or male gametophyte fragments were 4 temperature (5, 10, 15 and $20^{\circ}C$), 4 irradiance (5, 10, 20 and $40{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) and 3 photoperiod (14:10, 12:12 and 10:14 h L:D). Female and male gametophyte fragments were maintained in active regeneration without reaching sexual maturity under $5{\sim}10^{\circ}C$, $5{\sim}10{\mu}mol{\cdot}m-2{\cdot}s-1$, 12:12h or 10:14h (L:D) and $15-20^{\circ}C$, $20-40{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, 14:10h (L:D), respectively. Sexual maturation of female and male gametophytes facilitated under $15^{\circ}C$, $20-40{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, 14:10h (L:D) and $5-10^{\circ}C$, $5-10{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, 10:14h (L:D), respectively. These results provide basic informations to control the regeneration or maturation of the free-living gametophytes for artificial seed production of E. cava.

• 환경생물
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• 제17권3호
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• pp.331-335
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• 1999

광주기가 방사선에 의해 유발된 자주달개비 체세포돌연변이에 미치는 영향을 실험적으로 평가하였다. 포트에서 생육된 Tradescantia 4430 식물체에 코발트 선원으로부터 0.3, 0.5및 1.0Gy의 감마선을 조사하였으며 수술털 세포에 나타나는 분홍돌연변이를 분석하였다. 감마선 0.5 Gy를 기준선량으로 평가하였을 때 대조 실험군(CT)은 방사선 조사 후 6일 경과시부터 돌연변이율이 증가하기 시작하여 조사 후 10일째에 최고값에 도달하였다. 명기가 20시간인 실험군(PP20)에서는 방사선 조사 후 6일 경과시부터 돌연변이율이 증가하기 시작하여 조사 후 9일째에 최고값에 이르렀다. 반면에 명기가 4시간으로 제한된 실험군(PP4)에 있어서는 조사 후 10일째부터 돌연변이율이 급격히 증가하기 시작하여 16일 경과시 최고값에 도달하였다. CT실험군에 있어서 감마선 조사에 의하여 유발되는 분홍돌연변이 빈도의 증가계수 5.99($r^2$=0.99)에 비해 PP20과 PP4 실험군에 있어서의 각각의 돌연변이 빈도 증가계수는 6.93 ($r^2$=0.98)과 11.74($r^2$=0.99)로 PP20 실험군에 있어서는 15.7%, PP4 실험군은 95.9%의 증가 효과를 나타내었다. 결론적으로 비정상적인 광주기는 자주달개비 수술털에 대한 이온화 방사선의 분홍돌연변이 유발효과를 증가시키는 동시에 방사선에 의한 세포 유전자 손상의 회복을 상당기간 지연시키는 원인이 된다.

• 한국응용곤충학회지
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• 제29권4호
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• pp.277-285
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• 1990

담배나방 (Heliothis assulta Guenee)의 용휴면에 대한 유기와 종료요인 및 휴면 지속기간 등에 대하여 실험실과 야외개체에 대하여 실험하였다. 일장과 온도조건이 용휴면유기에 밀접한 관련을 맺으며 $20^{\circ}C$와 lOL/140의 팡주기하에서 유충율 키웠을 때 100%의 휴면율을 얻을 수 있었다. 그러나 $25^{\circ}C$의 경우에는 본 실험에서 시도한 가장 짧은 광주기인 8시간하에서도 약 85%의 휴면율만 나타내었다. 결국 휴면을 유기하는 임계일장이 $25^{\circ}C$에서는 12-12.5시간, $20^{\circ}C$에서는 14-14.5시간으로 계산되었으며 휴면유기 조건에 감응하는 발육단계는 4령과 5령유충기였다. 수원 및 우리나라 중부지역에서 9월 20일경부터 채집되는 노숙유충은 모두 휴면으로 들어갔다. 그러나 성충, 알, 용 등은 실험실내 휴면유기 조건 ($20^{\circ}C$, lOL/140)에 처리해도 아무런 반응이 없었다. 휴면기간은 휴면유기온도가 낮으면 길어지는 경향이었으며 광주기와는 무관한 것으로 나타났다. 휴면용들은 저온처리를 받지않아도 깨어나지만 저온처리 기간이 길어질수록 휴면기간은 짧아졌다.

• International Journal of Industrial Entomology and Biomaterials
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• 제5권1호
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• pp.1-12
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• 2002

Ecophysiologically diapause represents a syndrome of physiological and biochemical characteristics, all of which ensure survival during a long period of dormancy. Since, silkworm enters diapause as embryo at the early embryonic stage, the duration of egg life depends on the duration of embryonic diapause. The nature of diapause in silkworm, Bombyx mori, is primarily determined by genetic characters and endocrinologicnl mechanisms, mediated by environmental factors such as temperature and photoperiod. Hibernating potency value besides nucleic acid and carbohydrate metabolism, production and utilization of sorbitol are also equally responsible for induction, initiation, determination, maintenance and termination of diapause. Embryonic diapause in Bombyx moir, induced by active secretion of sub-oesophageal ganglion is attributed to hormonal system and metabolic adjustment, which serves to bring about a new physiological state. Metabolic conversion of trehalose to glycogen at induction, glycogen to sorbitol at initiation and sorbitol to glycogen at termination of diapause is correlated and in each metabolic shift a key enzyme becomes active in response to hormonal and environmental stimulation. An attempt has been made in this review article to discuss briefly the nature of embryonic diapause, influence of various factors on diapause nature, hormonal mechanism of diapause besides biochemical composition of egg, nucleic acid and carbohydrate metabolism, production and utilization of sorbitol in relation to induction, determination, maintenance, initiation and termination of diapause in the silkworm, Bombyx mori.

• 원예과학기술지
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• 제33권1호
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• pp.31-38
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• 2015

This study was carried out to investigate the relationship between endogenous polyamines (PAs) and floral bud differentiation in chrysanthemum (Chrysanthemum morifolium). In this study, PA content (free, bound, and conjugated) in apical buds, leaves, and roots changed appreciably during floral bud differentiation. PAs accumulated during series of processes such as floral induction, differentiation of floret primordia, and crown formation in apical buds; changes in PAs in apical buds may have a relationship with those in leaves and roots. The levels of free PAs and conjugated PAs [putrescine (Put) and spermine (Spm)] in apical buds rapidly increased during the initiation stage of floral bud differentiation, while free and conjugated spermidine (Spd) reached their highest levels at the stage of floret primordium differentiation. In the free, conjugated, and bound PA fractions, the changes in Spm content were negligible compared to those of Put and Spd throughout the experiment. These findings indicate that PAs participate in regulating the process of flower bud differentiation in chrysanthemum.

• International Journal of Industrial Entomology and Biomaterials
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• 제43권2호
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• pp.37-44
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• 2021

Mulberry silkworm is classified into uni, bi and multivoltine based on the frequency of diapause incidence. The variation in the incidence of diapause in bivoltine silkworm provides a unique opportunity to study the process of evolution of adaptive plasticity towards seasonal variations. The diapause expression in bivoltine silkworm is highly variable and is determined by environmental factors experienced by the maternal generation. Diapause in natural populations is functionally associated with the overwintering mechanism that facilitates survival in harsh winter conditions. In contrast, under standard commercial rearing conditions, the domesticated bivoltine silkworm is known to enter diapause in every generation. This paper presents a short review of the literature dealing with the role of temperature, photoperiod, diapause hormone and its receptor in diapause induction. Also, we briefly review the incidence of non-diapause eggs in bivoltine silkworm under controlled conditions.