Lamees Mohammad

Insect Low Temperature Biology
The Sinclair Lab at UWO

Lamees Mohammad

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Hi all! I’m a second-year Ph.D. student in the biology graduate program. I started in the Sinclair lab as an intern and honours thesis student on ‘team beetle. After I finished undergraduate studies, I became interested in neuroscience and understanding how the brain works so I went on an adventure to the University of Calgary and received my MSc.

For my Ph.D. project, I want to know how the nervous system of freeze-tolerant insects withstands freezing. Freezing causes neuronal dysfunction and tissue damage which will ultimately kill insects.

The cool thing about freeze-tolerant insects is after they freeze and thaw, the insects regain mobility suggesting neurological function is restored. I think these insects either protect their nervous systems from freezing or repair any damage after thawing.

Like everyone else in the lab, I am using Gryllus veletis to study the neurobiology of insect freeze tolerance. If you want to learn more about frozen cricket brains don’t hesitate to send an email, or DM me on Twitter (@cricketbrain1).

Here's the poster I presented at the 2022 APS intersociety meeting in San Diego (click here for a larger version)

Ice formation in the brain is usually harmful. Freeze tolerant insects withstand internal ice formation (i.e. are freeze tolerant), but how do they protect their nervous system during and after freezing? The spring field cricket (Gryllus veletis) is a model to explore the mechanisms underlying insect freeze tolerance. Acclimated G. veletis are freeze tolerant, and can withstand freezing at -8 °C for up to one week. By comparing acclimated and unacclimated crickets, we can identify basal changes associated with freeze tolerance, while comparison of frozen and chilled crickets allows us to dissect the differential effects of cold from ice formation. The metathoracic ganglion contains all components of the brain including nerve cell bodies, and a mass of nerve fibers and glial cells, making it an experimentally accessible system to study neuroprotection in freeze tolerance. We tested three non mutually-exclusive hypotheses: (1) that the central nervous system of G. veletis is inherently tolerant to freezing; (2) that acclimation confers freeze tolerance in the insect central nervous system, and (3) that the central nervous system of freeze tolerant insects is damaged by freezing but repaired after thawing. Using live/dead staining we found most nervous tissue cells from frozen freeze tolerant crickets are viable while most cells from frozen freeze intolerant nervous tissue were dead. Histology of metathoracic ganglion sections revealed swelling of frozen freeze-intolerant metathoracic ganglia analogous to cerebral edema, while the metathoracic ganglia from frozen freeze-tolerant crickets were intact. These findings suggest that freeze tolerant G.veletis protect their nervous system from freeze damage. Ongoing work is exploring the post-thaw recovery and performance of the ganglia using electrophysiology.