Individual Final Project

ABSTRACT

The project explores how diatoms adapt to rapidly changing salinity in transitional environments such as river plumes, where freshwater mixes with seawater. These zones are increasingly important under climate change, as shifting salinity patterns affect microbial survival and ecosystem stability. Understanding how diatoms respond at molecular and structural levels is critical, as they play a key role in global oxygen production and biogeochemical cycles.

The overall objective is to model and visualize adaptive mechanisms in diatoms under osmotic stress. The project hypothesizes that changes in ion transport and stress-response pathways can be linked to observable shifts in cell behavior and morphology, including frustule structure.

To address this, the project will

• design a controlled salinity gradient using a microfluidic chip;
• simulate adaptive mutations in key proteins using computational tools;
• visualize stress-response activation using a fluorescent reporter system such as GFP

The expected outcome is an integrated scientific and visual framework that connects molecular adaptation with environmental transitions, offering both biological insight and a platform for interdisciplinary exploration.

Aim 1: Experimental Aim

The first aim of my final project is to model and visualize stress-response activation in diatoms under controlled salinity gradients by utilizing a microfluidic chip system, fluorescent reporter constructs (e.g., GFP linked to stress-response genes), and computational protein design tools such as ESM-based models and AlphaFold for simulating adaptive mutations in ion transport and stress-related proteins.

Aim 2: Development Aim

The second aim is to extend this system by experimentally validating computationally predicted adaptive mutations, integrating optimized genetic constructs into diatom cells, and improving the microfluidic platform to allow long-term observation of adaptive dynamics and potential evolutionary changes across multiple generations.

Aim 3: Visionary Aim

The third aim is to translate laboratory-based insights into real-world environmental applications by developing strategies to enhance the salinity tolerance of diatoms in transitional ecosystems such as river plumes and estuaries. In the long term, this could contribute to maintaining ecosystem balance, supporting primary productivity, and strengthening the role of diatoms in global carbon and oxygen cycles.

BACKGROUND

Diatoms are key primary producers in aquatic ecosystems and contribute significantly to global carbon fixation and oxygen production. In transitional environments such as river plumes and estuaries, diatoms are exposed to rapid and often extreme fluctuations in salinity, requiring efficient adaptive responses. Previous studies have shown that osmotic stress in microalgae activates ion transport systems and stress-response pathways that regulate intracellular ion balance and protect cellular structures.[1] For example, research on salinity stress in diatoms demonstrates that ion transporters and compatible solute pathways play a central role in maintaining cellular homeostasis under changing environmental conditions.

Additionally, the change in the morphology of diatom frustules during the transition between freshwater and marine conditions is analyzed, as well as its dependence on genetic and environmental factors that determine adaptive mechanisms.[2]

[1] - Diatom community response to inland water salinization: a review, C. Stenger-Kovács, V. B. Béres, K. Buczkó, K. Tapolczai, J. Padisák, G. B. Selmeczy & E. Lengyel/Published: 26 April 2023, pages 4627–4663, (2023) [2] - Kamakura, S. et al. Morphological plasticity in response to salinity change in the euryhaline diatom Pleurosira laevis (Bacillariophyta). J. Phycol.58, 631–642 (2022)