Biology subjects

Mendes, F.

Publications and source records attributed to Mendes, F..

3 recordsLinked to original sources

bioRxiv2024

A flexible fluid delivery system for rodent behavior experiments

Experimental behavioral neuroscience relies on the ability to deliver precise amounts of liquid volumes to animal subjects. Among others, it allows the progressive shaping of behavior through successive, automated, reinforcement, thus allowing training in more demanding behavioral tasks and the manipulation of variables that underlie the decision making process (e.g.: reward magnitude). Here we introduce a stepper-motor-based, fully integrated, open-source solution, that allows the reproducible delivery of small (<1 {micro}L) liquid volumes. The system can be controlled via software using the Harp protocol (e.g.: from Bonsai or Python interfaces), or directly through a low-level I/O interface. Both the control software and electronics are compatible with a wide variety of motor models and mechanical designs. However, we also provide schematics, and step-by-step assembly instructions, for the mechanical design used and characterized in this manuscript. We provide benchmarks of the full integrated system using a computer-vision method capable of measuring across-trial delivery of small volumes, an important metric when having behavior experiments in mind. Finally, we provide experimental validation of our system by employing it in a psychophysics rodent task, and during electrophysiological recordings.

bioengineering↗

bioRxiv2024

The widely used cymoxanil fungicide impairs respiration in Saccharomyces cerevisiae via cytochrome c oxidase inhibition

Cymoxanil (CYM) is a synthetic acetamide fungicide that has been widely used to combat downy mildew diseases in grapevine cultures and late blight diseases in tomato and potato caused by the oomycetes Plasmopara viticola and Phytophthora infestans, respectively. Despite its extensive application, the biochemical mode of action of CYM remains elusive. Previous reports indicate that CYM affects growth, DNA and RNA synthesis in Phytophthora and inhibits cell growth, biomass production and respiration rate in the well-characterized fungal model Saccharomyces cerevisiae. We therefore used this model to further characterize the effect of CYM on mitochondria. We found that CYM inhibits oxygen consumption in whole cells after 3 h of exposure, which persists over time. Using isolated mitochondria, we demonstrated that CYM specifically inhibits cytochrome c oxidase (CcO) activity during oxidative phosphorylation. Based on molecular docking algorithms, we propose that CYM acts by blocking the interaction of cytochrome c (cyt c) with CcO, hampering electron transfer and inhibiting CcO catalytic activity. Although other targets cannot be excluded, our data offer valuable insights into the mode of action of CYM that can be instrumental to drive informed management of the use of this fungicide.

biochemistry↗

bioRxiv2024

The antifungal activity of cymoxanil is associated with proton pump inhibition and disruption of plasma membrane potential

Worldwide use of agrochemicals, particularly pesticides, is necessary to increase agricultural production to feed the ever-growing population. However, despite widespread use, the biochemical mode of action of many agrochemicals and their potential deleterious effects on the environment are poorly characterized. Cymoxanil (CYM) is a fungicide used to combat downy mildew diseases in grapevine cultures and late blight diseases in tomato and potato cultures caused by the oomycetes Plasmopara viticola and Phytophthora infestans, respectively. Previous reports indicate that CYM affects growth, DNA and RNA synthesis in Phytophthora and inhibits cell growth, biomass production and respiration rate in the well-characterized fungal model Saccharomyces cerevisiae. We therefore used this model to further dissect mechanisms underlying the toxicological effects of CYM. We found that CYM induced genome-wide alterations, particularly in membrane transporter systems. These alterations were associated with perturbations in lipid-raft organization and inhibition of Pma1p, leading to a decrease in plasma membrane potential and intracellular acidification. Altogether, these findings identify the plasma membrane as one of the targets of CYM and proposes a mode of action underlying its antifungal activity.

cell biology↗