Genome analysis of the cellular slime molds to understand the genetic system controlling cell differentiation

以细胞黏菌盘状盘齿钢霉（Dictyostelium disideum）为研究对象，研究其发育和分化的遗传调控。这种生物通常以单细胞变形虫的形式繁殖，但在饥饿时聚集并构建多细胞结构。首先，进行了大规模的cdna分析，以建立遗传资源。从5个发育阶段的细胞中构建了14个cDNA文库，测定了95,884个克隆的核苷酸序列，其中全长克隆72,703个。这些序列被组装成6790个独立的基因，占预测的12500个基因的54%。然后将这些资源用于逆向遗传和生物信息学分析。得到了以下结果：正常发育过程中的基因表达模式显示细胞聚集后表达基因发生了全面的剧烈变化。全株原位杂交显示茎前区有精细的花纹形成。提取260个基因编码可能的转录因子，通过实时荧光定量PCR获得了其中40个基因的精确表达模式。13个基因被破坏。根据野生型和断裂突变体发育过程中的基因表达模式，采用s系统计算得到9个可能的转录因子之间的遗传网络。将全长cDNA与基因组序列比对获得上游启动子序列，并根据表达特异性提取候选顺式调控元件。

The cellular slime mold, Dictyostelium discoideum, was used to understand the genetic control of development and differentiation. This organism normally proliferates as unicellular amoebae but gathers and constructs multicellular structures upon starvation. First, large scale analysis of cDNAs was performed to establish the genetic resources. Fourteen cDNA libraries were constructed from the cells at 5 developmental stages, and the nucleotide sequences of 95,884 clones, including 72,703 full-length ones, were determined. The sequences were assembled into 6,790 independent genes, which corresponded to 54% of the predicted 12,500 genes. These resources were then used for reverse-genetic and bioinformatic analyses. The following results were obtained.1. Gene expression patterns during normal development were obtained showing occurrence of the overall drastic changes in expressed genes after cell aggregation. Whole mount in situ hybridization revealed the fine pattern formation in the prestalk region.2. Two hundred and sixty genes were extracted to encode probable transcription factors, and precise expression patterns were obtained by real-time PCR for 40 of them. Thirteen genes were disrupted.3. The Genetic network among 9 probable transcription factors was obtained using the S-system calculation based on the gene expression patterns during development in the wild type and disruption mutants.4. Upstream promoter sequences were obtained by aligning the full-length cDNA and genome sequences, and candidate cis regulatory elements were extracted referring to the expression specificities.