Organ formation without cellular boundaries: development of the single-celled giant alga Caulerpa

没有细胞边界的器官形成：单细胞巨藻Caulerpa的发育

• 批准号: 2129803
• 负责人: Elliot Meyerowitz
• 金额: $ 119万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-05-15 至 2025-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2129803&HistoricalAwards=false
• 关键词: Organ; formation; without; cellular; boundaries

The project seeks to understand the genome and development of an unusual and little-studied plant, the green alga Caulerpa prolifera. Most plants and animals are composed of very large numbers of small cells, each serving a specific function in the organism as a whole. Caulerpa is as large as ordinary plants, and has the equivalents of leaves, stems and roots – but it is, exceptionally, one giant cell that can be up to a meter across. The single algal cell partitions into organs, rather than, as in other plants, the organs forming from the division and differentiation of many cells. To understand how organs develop without cell division and cellular specialization, experiments are planned to characterize the expression of genes in different organs when mature and as they develop, and to study the structure of the functionally different parts of this giant cell using electron microscopy. Additional experiments are planned to localize different gene transcripts to different locations within the cell; and to develop methods for introducing new genetic material to the alga to test mechanisms of gene expression control. The planned work will fill in knowledge of a little-known part of the ocean ecosystem, and will also inform about the growth and development, and potentially control, of Caulerpa, some species of which are invasive pests. Algae are also sustainable sources of industrial products. The knowledge gained has the potential to lead to novel products from a currently unused source. Undergraduate and graduate students, along with postdoctoral reasearchers, will be trained in state-of-the-art genomics methods while learning to address questions that span disciplines of development, cell biology and genomics.The chlorophyte alga Caulerpa prolifera poses a challenge to the cell theory, which considers organisms with differentiated parts to be social organizations of specialized cells. Caulerpa has fronds, stolons and rhizoids as differentiated organs, but consists of a single, giant, multinucleate cell. Preliminary work shows it to have a 35Mb genome containing around 11,000 genes. The goal of the proposed work is to learn how organs differentiate without cell division or cellular differentiation. There are five specific sets of experiments, whose aims are: complete the analysis of the genome with determination of long contigs; test differential RNA expression and differential presence of proteins in mature and developing organs; develop methods for in situ hybridization and FISH-seq for RNA localization in early developing organs; describe the internal structure and development of the different parts of the giant cell using serial block-face scanning electron microscopy; and attempt genetic transformation of the alga by biolistic delivery of fluorescent reporter constructs composed of promoter, gene and 3’ untranslated regions derived from endogenous genes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该项目旨在了解一种罕见的、很少被研究的植物--绿色蕨藻的基因组和发育。 大多数植物和动物都是由大量的小细胞组成的，每个小细胞在整个生物体中起着特定的作用。蕨藻与普通植物一样大，具有相当于叶、茎和根的大小--但例外的是，它是一个直径可达一米的巨细胞。 单个藻类细胞划分成器官，而不是像其他植物那样，由许多细胞分裂和分化形成的器官。 为了了解器官如何在没有细胞分裂和细胞特化的情况下发育，计划进行实验以表征成熟时和发育时不同器官中基因的表达，并使用电子显微镜研究该巨细胞功能不同部分的结构。 计划进行更多的实验，将不同的基因转录本定位到细胞内的不同位置;并开发将新的遗传物质引入细胞的方法，以测试基因表达控制的机制。 这项计划中的工作将填补海洋生态系统中鲜为人知的部分的知识，并将提供有关蕨藻的生长和发育以及潜在控制的信息，其中一些物种是入侵性害虫。 藻类也是工业产品的可持续来源。所获得的知识有可能从目前未使用的来源中产生新的产品。 本科生和研究生，沿着博士后研究人员，将接受最先进的基因组学方法的培训，同时学习解决跨越发育，细胞生物学和基因组学学科的问题。绿藻Caulerpa prolifera对细胞理论提出了挑战，该理论认为具有分化部分的生物体是专门细胞的社会组织。 蕨藻具有叶状体、匍匐茎和假根作为分化器官，但由单个、巨大、多核细胞组成。 初步研究表明，它有一个35 Mb的基因组，包含大约11，000个基因。 这项工作的目标是了解器官如何在没有细胞分裂或细胞分化的情况下分化。 有五组具体的实验，其目的是：完成基因组分析，确定长重叠群;测试成熟和发育器官中RNA的差异表达和蛋白质的差异存在;开发原位杂交和FISH-seq方法，用于早期发育器官中RNA的定位;用连续块面扫描电镜描述巨细胞不同部位的内部结构和发育;并尝试通过由启动子组成的荧光报告构建体的生物射弹递送来遗传转化所述大肠杆菌，该奖项反映了NSF的法定使命，并已被认为值得通过支持使用基金会的知识价值和更广泛的影响审查标准进行评估。