Morphogenesis of hierarchically patterned diatom biosilica: theory and experiment

硅藻细胞壁错综复杂的硅模式因其遗传编码的可变性和结构的复杂性而吸引了生物学家，因其应用潜力而吸引了工程师，因其美丽而吸引了自然科学家和外行。然而，我们并不了解引导生物二氧化硅自组织形成的物理和化学原理，这些生物二氧化硅图案具有规则间距的棱和纳米孔，也没有通过今天的材料合成获得类似复杂性的结构。我们的目的是揭示跨中心硅藻物种的生物硅模式形成的一般原理。为了实现这一目标，我们提出了物理指导的数学建模和有针对性的遗传扰动实验相结合的方法，以机械地理解分层生物二氧化硅图案是如何在生长隔间内形成的。由于硅藻二氧化硅形态形成实验分析的最新进展，该项目成为可能。它建立在Kröger和Friedrich小组之间建立的合作基础上，产生了一个关键硅藻物种分支肋骨模式形成的模型。我们的目标是在一个不断增长的二维领域中以相分离反应扩散系统的形式建立一个集成模型，该模型定量地解释了(i)支肋模式，（ii）肋之间的横向连接，以及（iii）有规律定位的孔隙，其中模型参数的可解释变化解释了三种具有径向对称的硅藻原型物种中不同的硅阀模式。以硅藻为模型系统，我们将推进对活细胞的遗传编码有机机制如何雕刻无机矿物的一般理解。

The intricate silica patterns of diatom cell walls have fascinated biologists for their genetically encoded variability and structural intricacy, engineers for their application potential, and natural scientists and laymen alike for their beauty. Yet, we do not understand the physical and chemical principles that guide the self-organized formation of biosilica patterns with regularly spaced ribs and nano-pores, nor are structures of similar complexity accessible through material synthesis today. We aim to reveal general principles of biosilica pattern formation across centric diatom species. To achieve this, we propose a combination of physics-guided mathematical modeling and targeted genetic perturbation experiments to mechanistically understand how hierarchical biosilica patterns form inside a growing compartment. This project has become possible through recent advances in experimental analysis of diatom silica morphogenesis. It builds on an established collaboration between the Kröger and Friedrich groups resulting in a model for the formation of branched rib patterns in a key diatom species. We aim for an integrated model in the form of a phase-separating reaction-diffusion system in a growing two-dimensional domain that quantitatively accounts for (i) branched rib patterns, (ii) transverse connections between ribs, and (iii) regularly positioned pores, where interpretable changes of model parameters account for different silica valve patterns in three prototypical diatom species with radial symmetry. Using diatoms as model system, we will advance a general understanding how the genetically-encoded organic machineries of living cells sculpture inorganic minerals.