Molecular and morphological analyses of maternal inheritance of Chlamydomonas mutants by fluorescence microscopy

母本遗传是指只有母本的叶绿体特征遗传给所有后代的现象。因此，我们试图分离出具有叶绿体或类叶绿体核(pt核)形态异常特征的突变体。分离到两个突变细胞(m-1、2)，分别含有约20个和50个类叶绿体。它们的类铂核数量分别是野生型细胞的2倍和5倍。从生理分析来看，每个叶绿体中的类铂核总DNA含量是野生型细胞的2倍和5倍，新形成的受精卵优先消化来自父本的类核被认为是造成叶绿体母系遗传现象的主要原因。在野生型细胞的双亲杂交后，受精卵在5h时优先消化的频率通常为100%。然而，当m-1细胞被用作fem…时，受精卵中的频率为85%。更多的ALE亲本要与野生型细胞的父本杂交。在以m-2细胞为母本的受精卵中，频率为80%。遗传分析表明，两个突变体各有一个基因突变。本实验中分离到的两个突变可能是连锁的，因为在两个突变细胞杂交后的31个四分体中没有得到四型四分体，而分离到两个突变细胞(m-3，4)，具有少量的pt类核数。遗传分析显示，他们有一个基因突变。从m-1和m-2突变细胞获得的结果可能表明，这些突变的受精卵对类铂核的优先消化需要较长的时间，这是因为优先消化的频率并不低。这表明母本遗传独立于pT类核体的DNA含量，并反对亲本中具有较多pT类核体DNA含量的亲本之一可以将其质体特征遗传给所有后代的说法。较少

Maternal inheritance is a phenomenon that the characteristics of plastids of only maternal parent are transmitted to all progenies. Therefore we attempted to isolate mutants which have morphologically abnormal characteristics of plastid or plastid nucleoids (pt nucleoids). Two mutant cells (m-1, 2), having about 20 and 50 of plastid nucleoids, respectively, were isolated. Their numbers of pt nucleoids were about two and five times that of wild type cells, respectively. From the physiological analysis, total DNA contents of pt nucleoids per plastid were two and five times that of a wild type cell.Preferential digestion of pt nucleoids derived from a male parent in newly formed young zygotes is thought to be the primary cause of the phenomenon of maternal inheritance of plastids. Usually the frequency of preferential digestion is 100% in the zygotes at 5 h. after crossing between two parents of wild type cells. However, the frequency was 85% in the zygotes when a m-1 cell was used as fem … More ale parent to cross to a male parent of wild type cell. In the zygotes when a m-2 cell was used as the female parent, the frequency was 80%.Genetic analysis showed that each of two mutants had one gene mutation. Two mutations isolated in the present experiment were probably linked because no tetra type tetrads were obtained among 31 tetrads after crossing between two mutant cells.Contrarily, two mutant cells (m-3, 4), having small pt nucleoid number, were isolated. Genetic analysis showed that they had one gene mutation. The results obtained from m-1 and m-2 mutant cells probably indicate that the preferential digestion of pt nucleoids in zygotes derived from these mutants requires a longer period because the frequencies of preferential digestion were not low. This suggests that maternal inheritance occurs independently on the DNA amount of pt nucleoids and opposes a proposal that one of parents having more DNA amount of pt nucleoids can transmit to its plastid characteristics to all progenies. Less