Research

The Toxopeus lab focuses on understanding how animals and their cells survive in challenging environments. This is important for understanding how organisms tolerate current environmental stressors, and how they might respond to future changes in their environment (e.g. due to global climate change). We use an integrative approach to answer questions about stress tolerance, employing molecular biology (e.g. qPCR), cell biology (e.g. confocal microscopy), bioinformatics (e.g. transcriptomics, metabolomics), functional genetics (e.g. RNA interference) and whole animal physiology.

Image showing that stress can affect insects at all biological levels of organization, from cells to tissues to the whole animal

Specifically, our lab focuses on how insects protect their cells at low temperatures (including when they are frozen!), and how this affects their overwintering success. For details on our research projects, read on!

The Challenges of Freezing

Remarkably, some insect species survive freezing, including the spring field cricket (Gryllus veletis). We assume that internal ice formation is challenging, but we don’t know much about how it harms organisms at the cellular level. We use G. veletis as a model to study how low temperatures and freezing damage cells, testing the hypotheses in the graphical summary below.

Hypothesized challenges associated freezing include those associated with low temperatures (e.g. loss of membrane fluidity), mechanical damage from ice (e.g. cell rupture), osmotic stress (e.g. dehydration-induced protein denaturation), and metabolic injury (e.g. oxidative damage over time)

Interested in learning more? Read this review about insect freeze tolerance.

The Cell Biology of Freeze Tolerance Acclimation

The spring field cricket (Gryllus veletis) becomes freeze-tolerant in the Fall, allowing it to survive internal ice formation. We know that acclimation to Fall conditions (i.e. low temperatures and short days) is required for freeze tolerance in this species. However, we know little about the cellular changes that occur during acclimation, which could protect against the challenges associated with freezing. We use G. veletis as a model to study how animals might modify their cell biology to promote freeze tolerance, testing the hypotheses in the graphical summary below.

Hypothesized cellular changes during acclimation include membrane and cytoskeletal remodelling, chaperone and antioxidant accumulation, decreased cell proliferation, and altered biochemical pathway activity

Interested in learning more? Read about previous research on the physiology and transcriptomics of acclimation in these crickets.

The Biochemistry and Genetics of Freeze Tolerance

The spring field cricket (Gryllus veletis) substantially alters its gene expression and metabolite composition when it becomes freeze-tolerant, and previous work has suggested that several genes and small molecules (e.g. cryoprotectants) are important for surviving freezing. We use methods to manipulate gene expression (e.g. RNA interference) and metabolite concentrations in these crickets to test their function in freeze tolerance – both for survival of the whole animal and its cells.

Interested in learning more? Read about previous experiments on cryoprotectants in these crickets, and/or the transcriptomics of acclimation in these crickets.