Stefane Saruhashi

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I received my BSc, teaching degree, and MSc in Biological Science from the University of Sao Paulo, Brazil - yes, Iím Brazilian! During my undergrad, I mostly worked with amphibians and lizards. I worked with the gliding lizards Draco spp. when I studied aboard at the University of New South Wales, and I described the daily thermal regulation and energetic demand of the toad Rhinella icterica for my honourís thesis.

In my Masterís research, I got into the world of insect physiology, studying the thermal sensitivity of a species from the complex Anastrepha frateculus. When I was about to finish my degree in 2019, I met Brent at the symposium ISEPEP 9 and decided to join the Sinclair lab!

 

I started my PhD at Western University in 2020, to explore the cellular mechanisms underlying the freeze-tolerant of the cricket, Gryllus veletis. Iím investigating whether and how how the crickets protect or repair their mitochondria, the powerhouse of the cell, from freeze-injury in the highly metabolically active tissue, Malpighian tubules.  

 

If you like our work, feel free to email me!


Here is a link to my most recent poster, from the CSZ 2023 meeting in Saskatoon (click to enlarge):


Many insects can withstand internal ice formation (i.e. are freeze tolerant). However, the sub-cellular processes associated with freeze tolerance are poorly understood. We use the spring field cricket Gryllus veletis as a model freeze tolerant insect: By comparing acclimated and non-acclimated crickets, we can distinguish the basal changes associated with acquiring freeze tolerance, and by comparing chilled and frozen crickets, we can disentangle the effects of cold from ice formation. Frozen mitochondrial samples are rarely viable, yet G. veletis is able to return to normal Ė or even increased Ė whole organism metabolic rate after freezing and thawing, which implies that they are able to either protect their mitochondria, or rapidly repair damage after thawing. We used high-resolution respirometry on Malpighian tubule tissue to measure the function of mitochondria in response to acclimation and freezing. Acclimated crickets had lower state 3 respiration than their unacclimated counterparts, but increased mitochondrial respiration after cold exposure. By contrast, frozen unacclimated crickets had decreased state 3 respiration upon thawing. This decrease appears to be driven by damage to the inner mitochondrial membrane. We are currently using transmission electron microscopy to explore the physical damage to the mitochondria, and a range of assays to understand the oxidative damage implications of freezing for mitochondria. 

Stefane is an Asian woman wearing a knitted hat and scarf and sunglasses, enjoying the sunshine in a snowy forest.