Eyespot-assembly mutants in Chlamydomonas reinhardtii.
Eyespot-assembly mutants in Chlamydomonas reinhardtii.
复制标题
莱茵衣藻的眼斑组装突变体。
DOI：
10.1093/genetics/153.2.721
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发表时间：
1999
期刊：
影响因子：
3.3
通讯作者：
Dieckmann,CL
中科院分区：
文献类型：
--
作者：
Lamb,MR;Dutcher,SK;Worley,CK;Dieckmann,CL
莱茵衣藻是一种单细胞绿色藻类，通过一种感光细胞器（眼斑）对光进行感光。眼斑由细胞质膜中的光感受器和Ca++通道信号转导组分和大叶绿体的下层区域中的反射性类胡萝卜素色素层组成。为了确定组件的定位和组装的功能性眼点的重要性，大量收集的nonphototactic突变体进行了筛选与异常色素点。确定了4个位点。eye 2和eye 3突变体没有色素斑。min 1突变体具有比野生型更小的眼点。MLT 1（PTX 4）突变体具有多个眼点。MIN 1、MLT 1（PTX 4）和EYE 2基因座彼此紧密连锁; EYE 3与其他三个基因座不连锁。eye 2和eye 3突变体对min 1和mlt 1突变是上位性的;所有双突变体都是无眼的。min 1 mlt 1双突变体具有合成表型;它们是无眼的或具有非常小的错位的眼点。超微结构研究表明，min 1突变体是有缺陷的物理连接之间的质膜和叶绿体被膜的色素颗粒的区域。这四个位点的表征将提供一个开始的理解眼点组装和定位在细胞中。
Chlamydomonas reinhardtii is a single-celled green alga that phototaxes toward light by means of a light-sensitive organelle, the eyespot. The eyespot is composed of photoreceptor and Ca++-channel signal transduction components in the plasma membrane of the cell and reflective carotenoid pigment layers in an underlying region of the large chloroplast. To identify components important for the positioning and assembly of a functional eyespot, a large collection of nonphototactic mutants was screened for those with aberrant pigment spots. Four loci were identified. eye2 and eye3 mutants have no pigmented eyespots. min1 mutants have smaller than wild-type eyespots. mlt1(ptx4) mutants have multiple eyespots. The MIN1, MLT1(PTX4), and EYE2 loci are closely linked to each other; EYE3 is unlinked to the other three loci. The eye2 and eye3 mutants are epistatic to min1 and mlt1 mutations; all double mutants are eyeless. min1 mlt1 double mutants have a synthetic phenotype; they are eyeless or have very small, misplaced eyespots. Ultrastructural studies revealed that the min1 mutants are defective in the physical connection between the plasma membrane and the chloroplast envelope membranes in the region of the pigment granules. Characterization of these four loci will provide a beginning for the understanding of eyespot assembly and localization in the cell.