Burton W G, Grabowy C T, Sager R
Proc Natl Acad Sci U S A. 1979 Mar;76(3):1390-4. doi: 10.1073/pnas.76.3.1390.
The different metabolic paths followed by homologous chloroplast DNAs of maternal and paternal origins in zygotes of Chlamydomonas were examined by prelabeling parental cells, before mating them, with [3H]adenine, [3H]thymidine, and [3H]deoxycytidine. Within 6 hr after mating, maternal chloroplast DNA was extensively methylated to 5-methylcytosine and its bouyant density decreased. Paternal chloroplast DNA was largely degraded. Some radioactivity from deoxycytidine of maternal origin reappeared in thymine, and residual paternal DNA contained radioactivity in a base tentatively identified as uracil. These results confirm and extend our previous findings and support our hypothesis that modification (methylation) and restriction enzymes determine maternal inheritance of chloroplast DNA and that the two parental DNAs have different metabolic fates within the zygote.
通过在交配前用[3H]腺嘌呤、[3H]胸腺嘧啶核苷和[3H]脱氧胞苷预标记亲本细胞，研究了衣藻合子中母本和父本来源的同源叶绿体DNA所遵循的不同代谢途径。交配后6小时内，母本叶绿体DNA大量甲基化为5-甲基胞嘧啶，其浮力密度降低。父本叶绿体DNA大部分被降解。母本来源的脱氧胞苷中的一些放射性重新出现在胸腺嘧啶中，残留的父本DNA在一个初步鉴定为尿嘧啶的碱基中含有放射性。这些结果证实并扩展了我们之前的发现，支持了我们的假设，即修饰（甲基化）酶和限制酶决定了叶绿体DNA的母系遗传，并且两个亲本DNA在合子中有不同的代谢命运。
