Biology subjects

Guyot, F.

Publications and source records attributed to Guyot, F..

3 recordsLinked to original sources

bioRxiv2024

Heat flows solubilize apatite to boost phosphate availability for prebiotic chemistry

Phosphorus is an essential building block of the most prominent biomolecules, such as polynucleic acids, and has likely played that role since the beginning of life. Despite this importance for prebiotic chemistry, phosphate could not be supplied by the atmosphere, and had to be fueled mainly by geological phosphate sources. However, phosphorus was scarce in Earths rock record and often bound in poorly soluble minerals, with the calcium phosphate mineral apatite as key example. While specific chemical boundary conditions that bind calcium have been used to address this so-called phosphate problem, a fundamental process that solubilizes and enriches phosphate from geological sources remains elusive. Here, we show that ubiquitous heat flows through rock cracks can liberate phosphate from apatite by the selective removal of calcium. Phosphates surprisingly strong thermophoresis not only achieves its 100-fold up-concentration in aqueous solution, in particular it also boosts its solubility by two orders of magnitude. We show that the heat-flow-solubilized phosphate can feed the synthesis of trimetaphosphate, increasing the conversion 260-fold compared to the thermal equilibrium case. Heat flows thus enhance solubility as a geological parameter to unlock apatites as phosphate source for prebiotic chemistry, providing a key element in solving early lifes phosphate problem.

biophysics↗

bioRxiv2022

Molecular Acclimation of Halobacterium salinarum to Halite Brine Inclusions

1Halophilic microorganisms have long been known to survive within the brine inclusions of salt crystals, as evidenced by the change in color for salt crystals containing pigmented halophiles. However, the molecular mechanisms allowing this survival has remained an open question for decades. While protocols for the surface sterilization of halite (NaCl) have enabled isolation of cells and DNA from within halite brine inclusions, "-omics" based approaches have faced two main technical challenges: (1) removal of all contaminating organic biomolecules (including proteins) from halite surfaces, and (2) performing selective biomolecule extractions directly from cells contained within halite brine inclusions with sufficient speed to avoid modifications in gene expression during extraction. In this study, we present methods to resolve these two technical challenges. In addition, we apply these methods to perform the first examination of the early acclimation of a model haloarchaeon (Halobacterium salinarum NRC-1) to halite brine inclusions. Examinations of the proteome of Halobacterium cells two months post-evaporation revealed a high degree of similarity with stationary phase liquid cultures, but with a sharp down-regulation of ribosomal proteins. Low quantities of RNA from halite brine inclusions corroborate the hypothesis of low transcriptional and translational activities. While proteins for central metabolism were part of the shared proteome between liquid cultures and halite brine inclusions, proteins involved in cell mobility (archaellum, gas vesicles) were either absent or less abundant in halite samples. Proteins unique to cells within brine inclusions included transporters, suggesting modified interactions between cells and the surrounding brine inclusion microenvironment. The methods and hypotheses presented here enable future studies of the survival of halophiles in both culture model and natural halite systems.

microbiology↗

bioRxiv2020

Engineering E. coli for magnetic control and the spatial localization of functions

The fast-developing field of synthetic biology enables broad applications of programmed microorganisms including the development of whole-cell biosensors, delivery vehicles for therapeutics, or diagnostic agents. However, the lack of spatial control required for localizing microbial functions could limit their use and induce their dilution leading to ineffective action or dissemination. To overcome this limitation, the integration of magnetic properties into living systems enables a contact-less and orthogonal method for spatiotemporal control. Here, we generated a magnetic-sensing Escherichia coli by driving the formation of iron-rich bodies into bacteria. We found that these bacteria could be spatially controlled by magnetic forces and sustained cell growth and division, by transmitting asymmetrically their magnetic properties to one daughter cell. We combined the spatial control of bacteria with genetically encoded-adhesion properties to achieve the magnetic capture of specific target bacteria as well as the spatial modulation of human cell invasions.

synthetic biology↗