Involvement of indole-3-acetic acid in the circadian growth of the first internode of Arabidopsis

The extension rate of the first inflorescence node of Arabidopsis was measured during light/dark or continuous light exposure and was found to exhibit oscillations which showed a circadian rhythmicity. Decapitation induced a strong inhibition of stem extension. Subsequent application of IAA restored growth and the associated extension–rate oscillations. In addition, IAA treatments, after decapitation, re-established the circadian rhythmicity visible in the intact plants during free run. This indicates that the upper zone of the inflorescence has a major influence on the extension rate of floral stems and implies a role for auxin. Application of N-(1-naphthyl)phthalamic acid, an IAA transport inhibitor, to an intact floral stem inhibited growth and the rhythmicity in the extension rate oscillations, indicating that IAA polar transport may play a role in the dynamics of stem elongation. Furthermore, IAA-aspartate application, after decapitation, did not restore growth and rhythmicity. Nevertheless, biochemical analysis of IAA and IAA-aspartate demonstrated circadian fluctuations of the endogenous levels of both compounds. These observations suggest that IAA metabolism is an essential factor in the regulation of the circadian growth rhythm of Arabidopsis floral stems. Received: 21 September 1998 / Accepted: 23 January 1999     

骚扰阿蚊生物学的实验室研究

选育采自上海的骚扰阿蚊实验室品系,成蚊可在26×20×20cm蚊笼内饲养繁殖.该品系蚊虫在实验室养殖条件下:卵、幼虫及蛹期分别为4.02天、9.79天和3.99天.孵化、化蛹及羽化率分别为80.25%、82.66%和97.42%.成蚊的性比为1.00.喂糖水雌蚊、喂鼠血雌蚊和雄蚊的寿命分别为29.27天、61.96天和28.75天.成蚊一生平均产卵1.4次,每蚊平均产卵163.28粒.各变态期转换时间具有明显的昼夜节律,孵化和羽化主要在白昼而产卵,蜕皮及化蛹集中在黑夜.     

秦岭羚牛中独栖现象的初步观察

在群栖的秦岭羚牛种群中,存在着少数单独活动的羚牛, 称为独牛。野外见到独牛50只次, 占见到羚牛总数的4.59 %。独牛中有老年雄性个体、青壮年雄性个体、雌性个体、亚成体和幼仔。在繁殖季节独牛出现的次数最多, 其中大部分是雄性个体, 也有雌性个体。与羚牛的四川亚种不同, 在秦岭亚种中很少见到公牛集群的现象。羚牛种群中独牛的形成主要与繁殖有关, 同时还与疾病及防御迁移有关。独牛在不同季节、不同生境内均可见到 , 绝大多数老年独牛活动区域的海拔高度低于集群的羚牛活动的高度。老年独牛在离群活动后,其活动节律与群体中的雄牛有一定的差异, 这种差异在夜间的活动时间和活动率方面表现得更加明显。     

长爪沙鼠与黑线仓鼠的温度选择比较

本文使用自制的陆生动物温度选择仪,对长爪沙鼠和黑线仓鼠的温度选择进行了比较,结果表明,长爪沙鼠的选择温度(29.06±0.62℃)较黑线仓鼠(26.65±0.64℃)高。这种差异可能与两种鼠的栖息环境及昼夜节律的不同有关。     

The Effect of Activity on the Waking Temperature Rhythm in Humans

Nine healthy female subjects were studied when exposed to the natural light-dark cycle, but living for 17 “days” on a 27h day (9h sleep, 18h wake). Since the circadian endogenous oscillator cannot entrain to this imposed period, forced desynchronization between the sleep/activity cycle and the endogenous circadian temperature rhythm took place. This enabled the effects of activity on core temperature to be assessed at different endogenous circadian phases and at different stages of the sleep/activity cycle. Rectal temperature was measured at 6-minute intervals, and the activity of the nondominant wrist was summed at 1-minute intervals. Each waking span was divided into overlapping 3h sections, and each section was submitted to linear regression analysis between the rectal temperatures and the total activity in the previous 30 minutes. From this analysis were obtained the gradient (of the change in rectal temperature produced by a unit change in activity) and the intercept (the rectal temperature predicted when activity was zero). The gradients were subjected to a two-factor analysis of variance (ANOVA) (circadian phase/ time awake). There was no significant effect of time awake, but circadian phase was highly significant statistically. Post hoc tests (Newman-Keuls) indicated that gradients around the temperature peak were significantly less than those around its trough. The intercepts formed a sinusoid that, for the group, showed a mesor (±SE) of 36.97 (±0.12) and amplitude (95% confidence interval) of 0.22°C (0.12°C, 0.32°C). We conclude that this is a further method for removing masking effects from circadian temperature rhythm data in order to assess its endogenous component, a method that can be used when subjects are able to live normally. We suggest also that the decreased effect of activity on temperature when the endogenous circadian rhythm and activity are at their peak will reduce the possibility of hyperthermia.     

高原鼢鼠(Myospalax baileyi)的挖掘活动及其种群数量统计方法的探讨

作者对高原鼢鼠的年挖掘活动规律,及其与气候、植物地下生物量和物候等环境因子的关系进行了研究。对不同季节内的日掘土活动节律进行了比较分析,并依其活动规律探讨了用土丘数估测鼠数量的可行性。     

侧金盏花成株年生长节律生理特性的研究

本文对侧金盏花成株两次生长两次休眠年生长节律的某些生理的月变化进行了研究。发现冬眠期和早春可溶性糖含量、可溶性蛋白质含量、脯氨酸含量、抗氰呼吸明显提高,入冬前淀粉酶活性提高,过氧化氢酶活性在寒冷和高温季节提高。在春天生长旺盛季节,淀粉在根中贮存量高达43%(DW)。     

Inspiratory muscle activity during bird song

The apparently continuous flow of bird song is in reality punctuated by brief periods of silence during which there are short inspirations called minibreaths. To determine whether these minibreaths are accompanied, and thus perhaps caused, by activity in inspiratory muscles, electromyographic (EMG) activity was recorded in M. scalenus in zebra finches and in M. scalenus and Mm. levatores costarum in cowbirds, together with EMGs from the abdominal expiratory muscles, air sac pressure and tracheal airflow. EMG activity in Mm. scalenus and levatores costarum consistently preceded the onset of negative air sac pressure by ∼11 ms during both quiet respiration and singing in both species. The electrical activity of these two muscles was very similar. Compared with during quiet respiration, the amplitude of inspiratory muscle EMG during singing was increased between five- and 12-fold and its duration was decreased from >200 ms to on average 41 ms during minibreaths, again for both species, but inspiratory muscle activity did not overlap with that of the expiratory muscles. Thus, there was no indication that the inspiratory muscles acted either to shorten the duration of expiration or to reduce the expiratory effort as might occur if both expiratory and inspiratory muscles were simultaneously active. Inspiratory and expiratory muscle activities were highly stereotyped during song to the extent that together, they defined the temporal pattern of the songs and song types of individual birds. © 1998 John Wiley & Sons, Inc. J Neurobiol 36: 441–453, 1998     

大鼠松果体Clock基因和芳烷脘N-乙酰基转移酶基因的昼夜节律性表达及光照影响

探讨12h光照、12h黑暗交替(12h-light：12h-dark cycle,LD)及持续黑暗(constant darkness,DD)光制下松果体Clock基因和芳烷脘N-乙酰基转移酶基因(arylalkylamine N-acetyltransferase gene,NAT)是否存在昼夜节律性表达及其光反应变化。Sprague-Dawley大鼠在LD和DD光制下分别被饲养4周(n=36)和8周(n=36)后,在一昼夜内每隔4h采集一组松果体组织(n=6),提取总RNA,用竞争性定量RT-PCR测定不同昼夜时点样品中Clock及NAT基因的mRNA相对表达量,通过余弦法和ClockLab软件获取节律参数,并经振幅检验是否存在昼夜节律。结果如下：(1)在DD或LD光制下,松果体Clock和NAT基因mRNA的表达均呈现夜高昼低的节律性振荡(P＜0．05)。(2)与DD光制下比较,LD光制下松果体Clock和NAT基因的表达振幅及峰值相的mRNA水平均降低(P＜0．05)。(3)在DD或LD光制下,Clock和NAT基因之间显示相似的节律性表达(P＞0．05)。结果表明,Clock和NAT基因在松果体中存在同步的内源性昼夜节律表达,光照作用可使其表达下调。     

Rhythmic activities of isolated and clustered pacemaker neurons and photoreceptors of Aplysia retina in culture

Each eye of Aplysia contains a circadian clock that produces a robust rhythm of optic nerve impulse activity. To isolate the pacemaker neurons and photoreceptors of the eye and determine their participation in the circadian clock and its generation of rhythmic autoactivity, the retina was dissociated and its cells were placed in primary cell culture. The isolated neurons and photoreceptors survived and vigorously extended neurites tipped with growth cones. Many of the photoreceptors previously described from histological sections of the intact retina were identified in culture, including the large R-type photoreceptor, which gave robust photoresponses, and the smaller tufted, whorled, and flared photoreceptors. The pacemaker neurons responsible for the rhythmic impulse activity generated by the eye were identified by their distinctive monopolar morphology and recordings were made of their activity. Isolated pacemaker neurons produced spontaneous action potentials in darkness, and pacemaker neurons attached to fragments of retina or in an isolated cluster interacted to produce robust spontaneous activity. This study establishes that isolated retinal pacemaker neurons retain their innate autoactivity and ability to produce action potentials in culture and that clusters of coupled pacemaker neurons are capable of generating robust autoactivity comparable to pacemaker neuron rhythmic activity recorded in the intact retina, which was previously shown to correspond to 1:1 with the optic nerve compound action potential activity. © 1996 John Wiley & Sons, Inc.