Biology subjects

Cazals, G.

Publications and source records attributed to Cazals, G..

3 recordsLinked to original sources

bioRxiv2026

Connecting gene expression and cytokinin signaling during meristem determinacy transition in the rice panicle

Structural complexity in the rice inflorescence (panicle) is determined by the activity of indeterminate meristems, which allow sequential branching events to occur but later acquire a determinate character that precludes the initiation of new growth axes. To better understand the underlying regulatory processes, we combined a detailed time-course of panicle development with tissue-specific sampling of meristems before and after the determinacy switch, monitoring global gene expression programs and hormone accumulation. This allowed the delineation of three dynamic transcriptional modules and the inference of gene regulatory networks highlighting hormone regulatory hubs associated with the indeterminate-to-determinate meristem transition. Our data confirm the importance of known regulators of inflorescence development and identify novel actors, notably genes encoding transcription factors, that were not previously described in the regulation of flowering. The combined biochemical and transcriptomic data support a model in which cytokinin signalling is particularly active during the proliferative branching phase, during which meristem maintenance is promoted while a feedback mechanism is also triggered, ultimately leading to the acquisition of determinate meristem fate later in development. HighlightInvestigating the molecular nature of rice inflorescence meristem determinacy, we studied temporal and spatial gene expression alongside hormone accumulation, identifying novel regulatory interactions and a key role for cytokinins.

plant biology↗

bioRxiv2025

Pleiotropic role of PAX cyclolipopeptides in the Xenorhabdus bacterium mutualistically associated with entomopathogenic nematodes

Xenorhabdus is an entomopathogenic bacterium involved in a mutualistic relationship with Steinernema nematodes. Xenorhabdus produces a multitude of specialized metabolites by Non-Ribosomal Peptide Synthetases (NRPSs) pathways to mediate bacterial-nematode- insect interactions. PAX cyclolipopeptides are a family of NRP-type molecules whose ecological role remains poorly understood. In this study, the pleiotropic role of PAX peptides in the life cycle of Xenorhabdus nematophila has been investigated. By mass spectrometry analysis, we first demonstrated that PAX peptides were detected from the pathogenic stage up to the necrotrophic stage. We discovered that the bromothymol blue adsorption phenotype historically used to discriminate Xenorhabdus variants was associated with the presence of PAX peptides. We found that PAX peptides were positively involved in biofilm formation and negatively involved in swimming motility. PAX peptides were also shown to promote in vivo the production of infective Steinernema juveniles, suggesting their involvement in the mutualistic relationship between Xenorhabdus and its nematode partner. Finally, we showed that the paxTABC cluster as well as PAX peptide production was conserved across the whole Xenorhabdus genus except in Xenorhabdus poinarii and Xenorhabdus ishibashii. This work has revealed multiple new ecological roles for NRP-type peptides. ImportanceXenorhabdus bacteria are models of particular interest for their mutualistic relationship with Steinernema nematodes and their ability to produce a wide range of natural NRP-type bioactive metabolites. These compounds are mostly studied for their medical or industrial applications, but their ecological role is poorly understood. This study provides a dynamic characterization of PAX cyclolipopeptide presence during Xenorhabdus nematophila life cycle, as well as confirmation of their production by 7 different strains within the Xenorhabdus genus. We revealed new multiple functions for PAX peptides in biofilm formation, swimming motility and juvenile nematode production. A deeper understanding of how PAX peptides interact with the nematode host would provide a better insight into the role of these cyclolipopeptides in bacterial-nematode mutualism.

microbiology↗

bioRxiv2021

Artemisinin-independent inhibitory activity of Artemisia sp. infusions against different Plasmodium stages including relapse-causing hypnozoites

Artemisinin-based combination therapies (ACT) are the frontline treatments against malaria worldwide. Recently the use of traditional infusions from Artemisia annua (from which artemisinin is obtained) or A. afra (lacking artemisinin) has been controversially advocated. Such unregulated plant-based remedies are strongly discouraged as they might constitute sub-optimal therapies and promote drug resistance. Here, we conducted the first comparative study of the anti-malarial effects of both plant infusions in vitro against the asexual erythrocytic stages of P. falciparum and the pre-erythrocytic (i. e., liver) stages of various Plasmodium species. Low concentrations of either infusion accounted for significant inhibitory activities across every parasite species and stage studied. We show that these antiplasmodial effects were essentially artemisinin-independent and were additionally monitored by observations of the parasite apicoplast and mitochondrion. In particular, the infusions significantly incapacitated sporozoites, and for P. vivax and P. cynomolgi, disrupted the hypnozoites. This provides the first indication that compounds other than 8-aminoquinolines could be effective antimalarials against relapsing parasites. These observations advocate for further screening to uncover urgently needed novel antimalarial lead compounds.

microbiology↗