Nicolas P, Heizmann P, Nigon V
C R Seances Acad Sci III. 1982 Jan 18;294(3):145-8.
In Euglena gracilis, pigment-less mutants appear spontaneously with a frequency of about 2-5 x 10(-3). Ultraviolet-irradiation increases the proportion of chlorophyll-less colonies to an upper limit where green colonies represent 4 x 10(-4) of the surviving ones. This limit indicate the occurrence of processes involving repair of the chloroplastic DNA. Most of the photosynthetic-deficient (phot-) mutants induced by ultraviolet irradiation are characterized by the presence of a reduced number of chloroplast DNA molecules showing deletions (phi class). Most of the phi- mutants present the phenotype phi- chlo- car-, where neither chlorophyll nor carotenoids are obvious; the phi- chlo- car+ mutants, devoid of chlorophyll but containing carotenoids, are obtained among the phi- strains with a frequency lower than 10(-3). The phot- mutants which belong to the cp- class are characterized by the maintenance of a great number of chloroplastic DNA molecules, where large deletions are absent; their occurrence after ultraviolet irradiation is low.
在纤细裸藻中，无色素突变体自发出现的频率约为2 - 5×10⁻³。紫外线照射会增加无叶绿素菌落的比例，直至达到一个上限，此时绿色菌落占存活菌落的4×10⁻⁴。这个上限表明存在涉及叶绿体DNA修复的过程。紫外线照射诱导的大多数光合缺陷（phot-）突变体的特征是叶绿体DNA分子数量减少且存在缺失（phi类）。大多数phi-突变体呈现phi- chlo- car-表型，即叶绿素和类胡萝卜素均不明显；phi- chlo- car+突变体不含叶绿素但含有类胡萝卜素，在phi-菌株中出现的频率低于10⁻³。属于cp-类的phot-突变体的特征是维持大量叶绿体DNA分子，不存在大的缺失；紫外线照射后它们的出现频率较低。
