Modelling growth and gene regulation in floral organs

生物是由不同的器官组成的，这些器官的形状和功能是由基因决定的。几十年的基因实验已经揭示了许多控制器官发育的关键基因，但我们仍然不明白这些基因如何共同作用，指导和组织成千上万的细胞的行为，这些细胞在每种器官类型的发育过程中繁殖并获得专门的角色。我们不了解器官发育的一个原因是，尽管我们可以单独描述基因之间和细胞之间的相互作用，但基因和细胞的集体行为太复杂，无法直观地掌握。因此，将需要计算机建模来描述和预测基因和细胞在发育过程中的集体行为。另一个限制是，我们对器官生长和支撑器官生长的细胞活动的测量过于粗糙，无法用于有关基因活动和生长的计算机模型。本项目旨在通过研究花器官（萼片和花瓣）的发育，促进我们对基因网络如何控制器官生长的理解。选择花器官有几个原因：它们的形状独特，但相对简单，它们的生长只基于细胞分裂和细胞扩张，没有细胞之间的相对运动，这在动物发育中经常看到。-许多控制花器官发育的基因已被深入研究，包括控制花器官形成的类型、器官的数量、形状和边界的基因。近年来，法国和英国的实验室已经开发出可视化和精确测量植物器官生长的方法，并在计算机中进行模拟。这些实验室开发了不同的方法来研究器官生长的早期阶段，包括细胞细节，或后期阶段，捕捉生长的更大特征。我们将结合现有的计算机模拟植物器官生长的专业知识和我们对调控基因的了解，建立计算机模型，模拟和预测关键基因与花器官生长之间的相互作用。为了实现这一目标，我们将：-直接观察和记录器官形成早期阶段的细胞行为-标记小细胞群并追踪它们在器官发育较长时期内的增殖和生长-利用这些信息构建花器官生长的计算机模拟-收集花器官发育过程中关键调控基因如何相互作用的信息，并建立这些相互作用的计算机模型。-将调控基因的作用纳入生长模型。为了做到这一点，我们将使用植物，我们可以操纵关键的调节基因来改变器官的身份，从萼片到花瓣，在不同的发育阶段，或在器官的不同区域。我们还将跟踪以关键调控基因表达为标志的细胞的行为。-使用计算机模型预测特定扰动（如调节基因表达改变）后的生长情况，并对这些预测进行实验测试（使用调节基因突变或功能改变的植物）。

Living beings are made of different organs whose shape and function are determined by genes. Decades of genetic experiments have revealed many key genes that control organ development, but we still do not understand how these genes act together to direct and organise the behaviour of the thousands of cells that multiply and acquire specialised roles during the development of each organ type. One reason why we do not understand organ development is that although we can describe the interactions between genes and between cells individually, the collective behaviour of genes and cells is too complex to grasp intuitively. Therefore, computer modelling will be required to describe and predict the collective behaviour of genes and cells during development. Another limitation is that our measurements of organ growth and of the cellular activities that underpin it are too crude to use in computer models relating gene activity and growth. The present project aims to advance our understanding of how networks of genes control organ growth, by studying the development of floral organs (sepals and petals). There are several reasons for choosing floral organs: - Their shapes are distinctive but relatively simple and their growth is based only on cell division and cell expansion, with no movement of cells relative to each other, as seen often in animal development. - Many genes controlling floral organ development have been intensively studied, including genes that control the type of floral organ formed, the number, shape and boundaries of organs. - In recent years, laboratories in France and in the UK have developed methods to visualise and measure precisely the growth of plant organs and simulate it in the computer. These labs have developed different approaches to study the very early stages of organ growth, with cellular detail, or later stages, capturing larger features of growth. We will combine the existing expertise on computer modelling of plant organ growth with our knowledge of regulatory genes to produce computer models that simulate and predict the interactions between key genes and growth of floral organs. To achieve this, we will: - Directly observe and record cell behaviour at early stages of organ formation - Mark small groups of cells and trace their proliferation and growth during longer periods of organ development - Use this information to construct computer simulations of floral organ growth - Collect information on how key regulatory genes interact with each other during floral organ development and build computer models of these interactions. - Integrate the action of regulatory genes into the growth models. To do this, we will use plants in which we can manipulate key regulatory genes to change the identity of organs from sepals to petals at different stages of development, or in different regions of the organs. We will also follow the behaviour of cells that are marked by expression of key regulatory genes. - Use the computer models to predict what happens to growth after specific perturbations (such as altered expression of regulatory genes) and test experimentally these predictions (using plants with mutation or altered function of regulatory genes).