Algal Cell Biology and Biophysics
The group of Dr. Adrian Nievergelt is interested in the fundamental molecular processes that define how algal cells work, with a special focus on ciliary biology and intracellular transport mechanisms. The group works primarily on the green model alga Chlamydomonas Reinhardtii and uses precision genetic engineering, advanced light and electron microscopy, biochemical methods and custom built instrumentation.
Algae are a diverse group of photosynthetic eukaryotes that are predominately aquatic. Their stunning diversity results in a large variety of potential uses for humans, whether it is as a source of nutrition or as a sustainable, photosynthetic chassis for biotechnology. Unlike flowering plants, algae commonly possess basal bodies and cilia which are used for motility. These microtubule based organelles are found throughout the tree of life and are essential for all mammalian life. These organelles are unique in their almost crystalline makeup and are characterized by their rotational axial symmetry and longitudinal repeats which span a length of many micrometers. Defects in this structure, generally referred to as ciliopathies, cause rare but often debilitating diseases in humans.
The unicellular green alga Chlamydomonas used in the lab has two such cilia which it uses for motility. Since Chlamydomonas is very easy to culture, fast growing, and can be readily genetically manipulated, it is a powerful model organism for ciliary biology, including a plethora of intracellular transport processes that are involved in assembly and maintenance.
The group uses a state of the art biochemical toolkit, advanced light microscopy and (cryo) electron microscopy together with precision genetic editing to gain structural and functional insights into the inner workings of algal cells. In addition to these established techniques, we develop new methods and instruments with the aim of answering, among other topics the following questions:
How are cilia assembled at a molecular level?
In mature cilia, over 2000 different proteins can be found. While much of the rigid architecture of motile cilia is known today, much of the process by which a cilium is built up from scratch is not well understood. We are interested in the molecular dynamics that happen during this incredibly complex assembly process which happens in mere minutes and involves a highly sophisticated system of active transport called intraflagellar transport.
How are cellular components transported to specific locations inside cells?
The plethora of proteins that cells are composed of have to be transported to their intended place. In cilia, these proteins are either integrated into the rigid central scaffold, called the axoneme, transported to the ciliary membrane or brought into the disordered soluble cilioplasm. Much of how this is achieved is unknown and we're especially interested in how some components are selectively transported or allowed to diffuse into the cilia, while others are prevented from entry.
What are the constituents of the ciliary membrane and what are their functions?
In all cilia, a membrane encloses the central axonemal structure. This membrane in turn contains a large variety of transmembrane proteins that are involved in diverse functions, from mechanical protection to chemical, mechanical and optical sensing of the environment. The composition and the structure and function of the constituents is not well known. We are interested in understanding how the ciliary membrane of microalgae acts as an interface to the direct environment and how sensing and transaction of mechanical force is achieved on a structural and biochemical level.