PNAS：剖析昼夜基因座间的内在关系

生物谷

德国雷根斯堡大学的Ralf  Stanewsky和同事们通过研究果蝇的Veela突变体，揭开了自然遗传突变体和昼夜基因座突变之间相互关系的秘密，该文发表在11月14日的PNAS杂志上。

持续照明条件下果蝇突变体表现出的昼夜节奏性（circadian  rhythmicity）特征，为科学家们阐明生物体内昼夜节律时间钟(circadian  clock；也可称生物钟；biological  clock；见备注)和环境同步化的内在机制提供重要线索。蛋白质Cryptochrome,  Timeless和Jetlag是至今发现的调控该同步化的关键蛋白。通过研究称作Veela的果蝇突变体（它可以在持续有关照的环境下表现出节奏性）,  Ralf  Stanewsky和同事们揭开了自然遗传突变体和昼夜基因座突变之间相互关系的秘密1。图谱展示了Veela紧挨在Timeless基因的附近，然而序列分析并没有发现任何Timeless的突变。但作者发现Veela果蝇有着Timeless的ls等位基因。野生型果蝇可以携带ls等位基因或s等位基因；ls等位基因编码的Timeless蛋白使得个体对光诱导的降解过程更不敏感。因为ls等位基因本身并不能揭示在Veela突变体身上发现的表型，作者随后分析了Jetlag基因，该基因就在Veela的附近。研究者们在该基因上发现了一个编码突变。作者怀疑Timeless  的ls等位基因与Jetlag突变的结合导致了Veela表型。确实地，当Jetlag突变遇到Timeless  的s等位基因时，果蝇表现出正常的表型。

1            N.  Peschel,  S.  Veleri,  and  R.  Stanewsky,  Proc  Natl  Acad  Sci  U  S  A  103  (46),  17313  (2006).

Lab:Institute  of  Zoology,  University  of  Regensburg,  Universitatsstrasse  31,  93040  Regensburg,  Germany.

备注：

生物节律主要有：1)　近日节律（20-28小时，即昼夜节律circadian  rhythm）；2)　近月节律（30±7天circamensual  rhythm）；3)　近年节律（12±2月circannual  rhythm）。生物节律具有四个基本特征：1）内源性；2)  遗传性；3）独立性；4)  可调性。

部分英文原文：

Veela defines a molecular link between Cryptochrome and Timeless in the light-input pathway to Drosophila's circadian clock

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Fig. 1. Locomotor activity of individual flies during constant light. Genotypes are indicated on top of each actogram accompanied by its corresponding autocorrelogram. Actograms show the raw activity of each fly, in which the height of each bar indicates the amount of locomotion during a 30-min interval. Autocorrelograms show period and rhythmicity index values of each fly as an objective way to determine rhythmicity (see Materials and Methods). The upper four flies also have their polymorphisms in regard to the tim and jet variants indicated (see text). Flies to the left are arrhythmic; individuals to the right are rhythmic. al I-40 and al I-3 each designate recombinants resulting from meiotic crossing over between two second chromosomes in females heterozygous for Veela and the marker combination al dp b pr. Both the I-40 and the I-3 recombinants carry the al marker and the jetc variant but differ with respect to tim. Note that al I-40 flies behaved arrhythmically in LL (like the controls), although they carry jetc.

更多原文链接：http://intl.pnas.org/cgi/content/figsonly/103/46/17313