How has cell shape been selected for in evolution?
Many filamentous organisms such as fungi display a diversity of shapes at the hyphal tips and it is not clear how and why this variability in shapes exist.
In a recent publication, we discovered that tip growing cells (including fungi, plants and protists) occupy the top of a "fitness cliff" whereby the shapes we observe in nature have principally been selected to optimize for fast growth rates.
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This has implications for our understanding of fungal and microbial evolution.
Hyphal tips in nature can vary from being rounded to pointed
Growing hypha of Achlya bisexualis with a pointed cell shape
Fitness Cliff demonstrating that observed shapes are selected to optimize elongation rates. Other shapes are possible at the base of fitness cliff but are unoccuppied
Dynamics of Pressurized Flow in Hyphal Networks
Hyphae behave as inflated pipes carrying cytoplasm and organelles. There is inherent flow of material towards the growing tip and hence hyphae can be viewed as pressurized pipes with a flow of cytoplasm and material. Interestingly, these 'pipes' are connected to each other in contiguous cytoplasmic networks, as they are no absolute separations. It is not clear how pressurized flow is distributed between connected hyphae.
In my research, I aim to study how flow may be distributed in the simple coenocytic mycelium of Achlya bisexualis. I employ hyperosmotic shocks to rapidly decrease the turgor pressure and investigate how pressure may be redistributed. So far, I have observed that hyperosmotic shock causes a differential response between adjacent hyphae, implying complex pressure redistribution between connected hyphae. I plan to study this phenomenon further
Young mycelium of Achlya bisexualis
