Analysis of mechanisms of maternal inheritance using laser fluorescence fluorimetory

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Attempts to isolate nucleases from young zygotes of C. reinhardtii showed that extracted nucleases required the presence of Ca++ for full activation and are thus call Nuclease C. They show polymorphism and are composed of six molecules with molecular masses of 16K,18K,21K,22K,and 26K. Nucleases with similar properties have been found in other algae. Since preferentail destruction of cp-nuclei of male origin is inhibited by EGTA. Nuclease C may be responsible for the preferential digestion of cpDNA in vivo. I proposed a mechanism for the regulation of maternal inhericance of cpDNA in young zygotes called as the active digestion hypothesis. Female gametes have the ability to protect their cpDNA against Nuclease C during gametogenesis by changing the domains surrounding female cpDNA. Soon after mating of male and female gametes, specific mRNAs are synthesized in a cell nucleus of female origin in the newly formed zygote. Then proteins which are coded by the mRNAs are synthesized de novo in the cytoplasm and directly or indirectly activated Nuclease C. Nuclease C preferentially digests cpDNA in the chloroplast of male origin. Since cpDNA of female origin remains, and is transmitted into progeny, maternal inheritance occurs.