Weeden N F
J Mol Evol. 1981;17(3):133-9. doi: 10.1007/BF01733906.
The hypothesis stating that chloroplasts were derived from a photosynthetic procaryote is explored at a genetic and biochemical level. A transfer of genetic material from the endosymbiont to the nucleus of the host cell is proposed along with a corollary argument that the protein products of such transferred genes have remained specific to the chloroplast. This model provides an explanation for the presence of plastid-specific isozymes which are coded by nuclear DNA. It also suggests that the genome of the endosymbiont contributed the information necessary for the biosynthesis of carotenoids and the "essential" amino acids and the assimilation of nitrate-nitrogen and sulfate-sulfur. Animal cells lack these capabilities not because such were lost subsequent to the divergence of the plant and animal lines, but because animal cells did not become host to the appropriate symbionts. Additional implications of this thesis are discussed.
关于叶绿体起源于光合原核生物的假说在遗传和生化层面进行了探讨。提出了遗传物质从内共生体转移到宿主细胞核的观点，以及这样一个必然的论点，即此类转移基因的蛋白质产物仍对叶绿体具有特异性。该模型解释了由核DNA编码的质体特异性同工酶的存在。它还表明，内共生体的基因组为类胡萝卜素和“必需”氨基酸的生物合成以及硝酸盐氮和硫酸盐硫的同化提供了必要信息。动物细胞缺乏这些能力，并非因为在动植物谱系分化后这些能力丧失了，而是因为动物细胞没有成为合适共生体的宿主。本文还讨论了这一论点的其他影响。
