ON TEMPERATURE INDEPENDENCE IN THE CLOCK SYSTEM CONTROLLING EMERGENCE TIME IN DROSOPHILA
ON TEMPERATURE INDEPENDENCE IN THE CLOCK SYSTEM CONTROLLING EMERGENCE TIME IN DROSOPHILA
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DOI：
10.1073/pnas.40.10.1018
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发表时间：
1954-01-01
影响因子：
11.1
通讯作者：
PITTENDRIGH, CS
中科院分区：
文献类型：
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作者：
PITTENDRIGH, CS
方法。这里给出的数据都是使用1950年从内华达州山脉的加州州马瑟收集的一株拟暗果蝇（Drosophila pseudobscura斯图尔特万特）获得的。杜布赞斯基培养物在160、210或260 ℃的恒温条件下培养。在下面指定的一些实验中，它们在自然波动的温度下升高。通过使用五对特定年龄限制的亲本来控制种群密度，在转移到新小瓶之前在小瓶中产卵48小时。交替光照（12小时）和黑暗（12小时）的条件（下文称为”LD”条件）用荧光灯获得，由定时开关控制。在本文中，“黎明”是用来表示在自然或实验文化的黑暗和光明的过渡。将一些培养物保持在恒定黑暗中，下文称为”DD“。“当培养物准备化蛹时，将一小段圆柱形棉牙塞放入小瓶中。几乎所有的化蛹都发生在这个塞子的尖端，然后从小瓶中取出，夹在一个装有20个这样的塞子的罐子里。根据给药的光照条件，用一个带塞子的有机玻璃漏斗或铝漏斗封闭罐。需要强调的是，在所有这些实验中，严格遵守了光照时间表。Au操作在绝对黑暗条件下进行。这种容器有几个优点：它们允许同时观察20个培养物的羽化时间（通过倒置和通过漏斗振出苍蝇）;避免了食物的掉落;在一个给定的实验中，20个这样的容器可以有效地进行操作，因此大量的苍蝇允许精确地估计时间事件。在LD条件下的出现模式。图1（A、B和C）显示了在三种温度下维持并每小时观察的LD培养物中出苗的分布。一种文化的出现活动是量化的：它在黎明后的几个小时内爆发。在自然界中最热和最干燥的上午和下午，它被抑制了（图2）。因此，无论温度条件如何，都有一个24小时的羽化节律。将允许的羽化活动时间限制在一天中最冷和最潮湿的时间内的适应意义是足够清楚的：刚羽化的果蝇失水的速度至少是成熟果蝇的两倍，而且当湿度太低时，它们的翅膀不能适当地展开。所有每日峰值的包络线形成一个分布，向右倾斜，在几天内传播，其数量取决于温度。每个尖峰的精确形状是它在包络中的位置的函数;最早的峰值向左倾斜，后来的峰值向右倾斜（图3）。此外，在三种温度下，峰的一般形状不同;在较高温度下，分布一般向右倾斜。解释的变化形状的峰值内的包络线是发展在一个
Methods.-Data given here were all obtained using a single strain of Drosophila pseudoobscura Sturtevant collected in 1950 from Mather, California, in the Sierra Nevada, by Professor Th. Dobzhansky. Cultures were raised under constanttemperature conditions at 160, 210, or 260 C. In some experiments, specified below, they were raised under naturally fluctuating temperatures. Population den-sity was controlled by using five pairs of parents of specified age limits, left to oviposit 48 hours in a vial before transfer to a fresh vial. Conditions of alternating light (12 hours) and darkness (12 hours), hereafter specified as" LD" conditions, were obtained with fluorescent lamps, controlled by a time switch. Throughout this paper" dawn" is used to designate the dark-light transition in a natural or ex-perimental culture. Some cultures were maintained in constant darkness, hereafter specified as" DD." When the cultures were ready to pupate, a short strip of cylindrical cotton dental plug was introduced into the vial. Virtually all pupation took place on the tip of this plug, which was then removed from the vial and clipped into a canister that held twenty such plugs. The canister was closed with a stop-pered funnelof either lucite or aluminum, according to the light conditions to be administered. It is emphasized that in all these experiments the light schedule was rigorously observed. AU manipulations were performed in absolute darkness when they fellin the dark period. The canistershave several advantages: they permit observation of eclosion time (by inverting and shaking out-flies through the funnel) in twenty cultures simultaneously; falling food is avoided; and in a given expeii-ment twenty such canisters may be handled with effective simultaneity, so that the huge number of flies permits a precise estimate of the timed event. Pattern ofEmergence under LD Conditions.-Figure 1 (A, B, and C) shows the distribution of emergence in LD cultures, maintained at three temperatures and observed hourly. The emergence activity of a culture is quantized: it occurs in bursts in the hours following dawn. It is inhibited throughout those hours of the late morning and afternoon that are in nature the hottest and driest (Fig. 2). There is, then, a 24-hour rhythm ofemergence, no matter what the temperature conditions are. The adaptive significance of restricting the allowed period for emergence ac-tivity to the coldest and wettest hours of the day is clear enough: emerging flies lose water at a rate at least double that of mature flies and fail to expand theirwings properly when the humidity is too low.The envelope of all the daily spikes forms a distribution, skewed to the right, spreading over several days, the number of which depends on the temperature. The precise shape of each spike is a function of its position in the envelope; the ear-liest peak is skewed to the left, later peaks to the right (Fig. 3). The general shape of peaks differs, moreover, at the three temperatures; the distributions are in general skewed more to the right at the higher temperatures. Explanation of the changing shape of peaks within the envelope is developed in a