Biophysical Society Thematic Meeting | Singapore

Mechanobiology of Disease

Thursday Speaker Abstracts

Mechanical Impact of Apoptosis in a Tissue Yusuke Toyama 1,2,3 .

1 Mechanobiology Institute, National University of Singapore, Singapore, 2 Department of Biological Sciences, National University of Singapore, Singapore, 3 Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore. Apoptosis, or programmed cell death, is the most common mechanism of eliminating damaged or unnecessary cells during embryonic development, tissue homeostasis, and certain pathological conditions. It has been well known that apoptotic cell is expelled from a tissue mainly by the formation and contraction of the actomyosin cables in the dying and the neighboring non-dying cells. However, this was not been correlated with the dynamics of adherens junction (AJ) and the temporal changes in tissue mechanical tension. We explored the extrusion process of apoptotic cell in developing Drosophila pupae. Here we show that in the middle of cell extrusion, AJs between apoptotic and non-dying cells become defective, with a reduction in the levels of AJ components, including E-cadherin. Concurrently, tissue tension is transiently released. Formation and contraction of a supra-cellular actomyosin cable forms in neighboring cells, brings the non-dying cells together and further reshapes tissue tension toward the completion of extrusion. The extrusion-associated mechanical force deforms not only the nearest-neighbor cells but also the surrounding tissue and contributes to large-scale tissue dynamics. All together, we conclude that a mechanical coordination between adhesion remodeling and tissue tension reshaping represents a mechanism of apoptotic cell extrusion.

Biogeography of in vivo Microbial Biofilms Marvin Whiteley , The University of Texas at Austin, Austin, TX, USA.

Biogeography is the study of the spatial distribution of species within an ecosystem across space and time. The field of microbial ecology has long focused on the micron-scale biogeography and its consequences in polymicrobial communities. For example, studies of the leaf-associated microbiota of plants show that the arrangement of single cells in structured polymicrobial communities is responsible for desiccation tolerance, persistence, and resistance to invading species. The biogeography of human-associated polymicrobial communities, including those in disease, has not been studied to similar depth. While it is now widely accepted that most polymicrobial communities living in natural environments, including the human body, form spatially structured consortia, the mechanisms used by microbes to form these communities is not understood. Here I will discuss the use of a microscopic three-dimensional printing strategy in combination with the micro-scale analytical technique scanning electrochemical microscopy to elucidate these mechanisms. This experimental framework has allowed for the assessment of the role of micro-scale spatial structure on bacterial interactions as well as important clinical phenotypes including antibiotic resistance.

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