Biology subjects

Deniset-Besseau, A.

Publications and source records attributed to Deniset-Besseau, A..

3 recordsLinked to original sources

bioRxiv2022

Cuticle architecture and mechanical properties: a functional relationship delineated through correlated multimodal imaging

O_LICuticle are multifunctional hydrophobic biocomposites that protect aerial organs of plants. Along plant development, plant cuticle must accommodate different mechanical constraints combining extensibility and stiffness, the corresponding structure-function relationships are unknown. Recent data showed a fine architectural tuning of the cuticle architecture and the corresponding chemical clusters along fruit development which raise the question of their impact on the mechanical properties of the cuticle. C_LIO_LIWe investigated the in-depth nanomechanical properties of tomato fruit cuticle from early development to ripening, in relation to chemical and structural heterogeneities by developing a correlative multimodal imaging approach. C_LIO_LIUnprecedented sharps heterogeneities were evidenced with the highlighting of an in-depth mechanical gradient and a soft central furrow that were maintained throughout the plant development despite the overall increase in elastic modulus. In addition, we demonstrated that these local mechanical areas are correlated to chemical and structural gradients. C_LIO_LIThis study shed light on a fine tuning of mechanical properties of cuticle through the modulation of their architecture, providing new insight for our understanding of structure-function relationships of plant cuticle and for the design of biosinpired material. C_LI

plant biology↗

bioRxiv2021

Plastic biodegradation: do Galleria mellonella larvae - bio-assimilate polyethylene? A spectral histology approach using isotopic labelling and infrared microspectroscopy.

Environmental pollution by non-biodegradable polyethylene (PE) plastics is of major concern, thus, organisms capable of bio-degrading PE are required. The larvae of the Greater Wax Moth, Galleria mellonella (Gm), were identified as a potential candidate to digest PE. In this study, we tested whether PE was metabolized by Gm larvae and could found in their tissues. We examined the implication of the larval gut microbiota by using conventional and axenic reared insects. First, our study showed that neither beeswax nor PE alone favour the growth of young larvae. We then used Fourier-Transform Infrared Microspectroscopy ({micro}FTIR) to detect deuterium in larvae fed with isotopically labelled food. Perdeuterated molecules were found in most tissues of larvae fed with deuterium labelled oil for 72 hours proving that {micro}FTIR can detect metabolization of 1-2 mg of deuterated food. No bio-assimilation was detected in the tissues of larvae fed with 1-5 mg of perdeuterated PED4 for 72 hours and 19-21 days, but micron sized PE particles were found in the larval digestive tract cavities. We evidenced weak bio-degradation of PE films in contact for 24 hours with the dissected gut of conventional larvae; and in the PED4 particles from excreted larval frass. Our study confirms that Gm larvae can bio-degrade PE but can not necessarily metabolize it.

ecology↗

bioRxiv2021

Consequences of the constitutive NOX2 activity in living cells: cytosol acidification, apoptosis, and localized lipid peroxidation

The phagocyte NADPH oxidase (NOX2) is a key enzyme of the innate immune system generating superoxide anions (O2*-), precursors of reactive oxygen species. The NOX2 protein complex is composed of six subunits: two membrane proteins (gp91phox and p22phox) forming the catalytic core, three cytosolic proteins (p67phox, p47phox and p40phox) and a small GTPase Rac. The sophisticated activation mechanism of the NADPH oxidase relies on the assembly of cytosolic subunits with the membrane-bound components. A chimeric protein, called Trimera, composed of the essential domains of the cytosolic proteins p47phox (aa 1-286), p67phox (aa 1-212) and full-length Rac1Q61L, enables a constitutive and robust NOX2 activity in cells without the need of any stimulus. We employed Trimera as a single activating protein of the phagocyte NADPH oxidase in living cells and examined the consequences on the cell physiology of this continuous and long-term NOX activity. We showed that the sustained high level of NOX activity causes acidification of the intracellular pH, triggers apoptosis and leads to local peroxidation of lipids in the membrane. These local damages to the membrane correlate with the strong tendency of the Trimera to clusterize in the plasma membrane observed by FRET-FLIM microscopy. HighlightsO_LITrimera is a tool to trigger a continuous ROS production in living cells C_LIO_LIContinuous NOX2 activity causes cytosol acidification and apoptosis C_LIO_LIROS overproduction leads to localized oxidation of the membrane lipids C_LIO_LITrimera tends to clusterize in the plasma membrane of COSNOX and COS-7 cells C_LI

biophysics↗