GENOME COMPLEXITY IN RHODOBACTER SPHAEROIDES 241

描述(改编自申请者摘要)：在不到十年的时间里 我们已经了解到细菌，也许还有一般的原核生物，都拥有 线形染色体和质粒，以及多条，但不同 染色体。到目前为止，人们一直认为原核生物含有 一种独特的圆形染色体。到目前为止，大约有5-7个不同的属 细菌被发现含有两条或更多条染色体，而且它是 有趣的是，这些属中的大多数已经被证明与 高等生物的细胞。这项研究，正如这里所描述的，旨在 提供了理解这一行的第一个实验方法 微生物发展。一种方法是基于观察到的 已证明有几个基因在第一和第二染色体之间是杂合的。 在细菌中，球形红杆菌为2.4.1。利用这一经过充分研究的 我们将确定细菌之间存在杂合性的程度 染色体I和II，无论两个成员是否为同源的 基因是有功能的，在什么生长条件下；基因的种类是什么 以及映射到每条染色体上的真正必要基因的类型 最后，这条发展路线是这个集团的所有成员所共有的吗 细菌，如果不是，为什么不呢？ 众所周知，杂合性可以增加这些人的“适合度”。 在其生命周期内表现出倍性的高等生物体。这有可能吗？ 原核生物是真的吗？如果是真的，又是如何做到的？因此，基因的杂合性程度 球形乳杆菌2.4.1及其杂合基因产生的条件 EXPRESS应有助于解决这一问题。虽然杂合子基因 配对也可以是必要的基因，不需要这样的先决条件。 因此，必须基因的种类和分布映射到 染色体I和II可能有助于揭示黄热病的起源(S) 球形乳杆菌2.4.1的多染色体状态。最后，因为有几个 在被发现为杂合子的基因对中，与基因家族非常相似 在高等生物中发现，我们也可能了解真核生物的起源 类型单元格及其夹杂物。

DESCRIPTION (Adapted from the Applicant's Abstract): In less than a decade we have learned that bacteria and perhaps prokaryotes in general, possess linear chromosomes and plasmids, as well as multiple, but different chromosomes. Heretofore it had been accepted that prokaryotes contained but a unique, circular chromosome. To date, some 5-7 different genera of bacteria have been found to contain two or more chromosomes and it is interesting that most of these genera have been shown to interact with the cells of higher organisms. This research, as described here, is designed to provide the first experimental approach to understanding this line of microbial development. One approach is based on the observation that several genes have been shown to be heterozygous between chromosomes I and II in the bacterium, Rhodobacter sphaeroides 2.4.1. Using this well studied bacterium we will determine the extent of heterozygosity existing between chromosomes I and II, whether or not both members of a pair of homologous genes are functional and under what growth conditions; what are the kinds and types of truly essential genes which are mapped to each chromosome and finally; is this line of development shared by all members of this group of bacteria and if not, why not? Heterozygosity is known to increase the "fitness" of those populations of higher organisms which show ploidy within their life cycle. Can this be true of prokaryotes, and if so, how? Thus, the extent of heterozygosity in R. sphaeroides 2.4.1 and the conditions under which heterozygous genes are expressed should help to address this question. Although heterozygous gene pairs can also be essential genes, no such prerequisite is necessary. Therefore, the kinds and distribution of essential genes which map to chromosomes I and II may help to reveal the origin(s) of the multi-chromosomal state in R. sphaeroides 2.4.1. Finally, because several of the gene pairs found to be heterozygous are very similar to gene families found in higher organisms, we may also learn the origins of the eukaryotic type cell and its inclusions.