Biology subjects

Collin, S.

Publications and source records attributed to Collin, S..

2 recordsLinked to original sources

bioRxiv2022

Membrane lipid adaptation of soil Gram-negative bacteria isolates to temperature and pH

3-hydroxy fatty acids (3-OH FAs) are characteristic components of the Gram-negative bacterial membrane, recently proposed as promising temperature and pH (paleo) proxies in soil. Nevertheless, to date, the relationships between the 3-OH FA distribution and temperature/pH are only based on empirical studies, with no work at the microbial level. This work investigated the influence of growth temperature and pH on the lipid profile in three strains of soil Gram-negative bacteria belonging to the Bacteroidetes phylum. Even though the non-hydroxy FAs were more abundant than the 3-OH FAs in the investigated strains, we showed the important role of the 3-OH FAs in the membrane adaptation of Gram-negative bacteria to temperature. The strains shared a common adaptation mechanism to temperature, with a significant increase in the ratio of anteiso vs. iso or normal 3-OH FAs at lower temperature. In contrast with temperature, no common adaptation mechanism to pH was noticed, the variations in the FA lipid profiles differing from one strain to another. The models envisioning the reconstruction of environmental changes in soils should include the whole suite of 3-OH FAs present in the membrane of Gram-negative bacteria, as all of them can be influenced by temperature or pH at the microbial level.

microbiology↗

bioRxiv2021

Hippocampal reconfiguration of events in mnemonic networks

It is widely assumed that episodic memories are not stored in isolation but rather in dynamic event networks. However, the mechanisms of the underlying dynamic of these representations, in particular how such networks are updated, remain elusive. In this study, we investigated the reconfiguration of events into event networks in the hippocampus by presenting new events that could update either one of two competing narratives. During the first session, participants viewed four animated movies, each representing a distinct narrative; two distinct narratives from the Jones family and two distinct narratives from the Smith family. During the second session, we re-exposed participants to snapshots of these narratives along with snapshots of new events from one of the two families, allowing updating of the acquired event networks of that family. Our findings show that the hippocampus integrated new events that relate to the old family, and then integrated these new events with the corresponding old events. Furthermore, hippocampal representations of the events within a narrative became better integrated after updating. Our results shed new light on the neural mechanisms underlying flexible mnemonic updating with realistic events and further advance our understanding of the structured reconfiguration of event networks in memory.

neuroscience↗