Biology subjects

Lejeune, R.

Publications and source records attributed to Lejeune, R..

3 recordsLinked to original sources

bioRxiv2025

Fetal magnetoencephalography based on optically pumped magnetometers

The fetus in the third trimester of gestation has already the remarkable capacity to process external sensory information in utero. So far, investigations of fetal brain responses to sensory information have mostly relied on cryogenic magnetoencephalography (MEG), which is suitable to record fetal brain activity and is not much affected by layers of maternal tissues. Nevertheless, this solution is extremely expensive and limited to a couple of laboratories worldwide. In this work, we took advantage of the next generation cryogenic-free MEG, that is MEG based on optically pumped magnetometers (OPM), to develop a system that could record both fetal and newborn brain responses to auditory stimulation in a longitudinal design. Twenty-one pregnant women in their late third trimester of gestation (35-40 weeks of gestational age) were exposed to sequences of 500 Hz tones. Fetal brain activity was recorded using a wearable belt equipped with OPM sensors arranged on the womens abdomen based on fetal head position. Results revealed that fetal OPM-MEG successfully recorded significant evoked brain responses to auditory stimuli that peaked ~300 ms post-stimulus at the group level. A similar auditory paradigm was performed with on-scalp OPM-MEG in 14 one-month-old infants, with 9 participants common to both timepoints. Infant responses showed a significant latency decrease compared to the fetal ones in terms of magnetometers; a decrease that did not reach significance level for virtual gradiometers. This work demonstrates the ability of OPM-MEG to non-invasively record fetal brain responses to external sensory stimuli. It paves the way for a wider use of fetal MEG to investigate fetal cognition and positions OPM-MEG as the most promising lifespan-compliant solution for monitoring early brain development.

neuroscience↗

bioRxiv2025

Phenological turnover matters when making trait-based predictions of plant-pollinator interactions

1. Understanding the processes determining species interactions is key to predicting and safeguarding ecological networks under rapid environmental change. One approach to estimating interactions is to use morphologies of taxa interacting across trophic levels to reveal suites of traits they are more likely to interact with (i.e. a trait niche). 2. Previous work studying these morphological trait niches has typically used interactions between species that are pooled in space and time. However, species assemblages, and the traits of individuals within species, can change across even small landscapes over a season, leading to morphological trait space being dynamically reshaped. Therefore, it is unclear how morphological trait turnover affects our inferences of trait niches, and our ability to answer this is in part limited by a lack of individual-level trait data. 3. Here, we directly address this by studying a montane Arctic plant-pollinator community over five growing seasons (>1,300 hours of fieldwork). Specifically, we linked every recorded plant-bumblebee interaction with the traits of the bee individual involved (n = 1,150), to investigate 1) whether plant taxa (n = 10) exhibited bee trait niches by interacting with specific regions of multidimensional trait space of visiting bumblebees, and 2) how our inference of these trait niches was affected by considering bumblebee trait turnover and plant taxon turnover. 4. When not considering turnover (interactions in space and time are pooled), plant taxa demonstrated bee trait niches. However, next we considered how bee trait space is reshaped over the elevational and seasonal gradient (especially with the emergence of different castes), and how this reshaping co-occurs with different spatiotemporal ranges of the plant taxa. From this we found the degree to which plant taxa exhibited trait niches declined significantly, and that seasonal reshaping of bee trait space was the primary driver of this trend. 5. Overall, in highly dynamic systems, like the Arctic, overlooking community turnover could mask and even overestimate the ability of morphology to explain interactions. Hence, determining how morphological traits of individual interaction partners are in phenological synchrony at localised scales will be fundamental to understanding the role morphology plays in underpinning plant-pollinator interactions.

ecology↗

bioRxiv2024

Mountain roads across the globe significantly alter local soil microclimates

Mountain roads have repeatedly shown to host significantly different plant species communities compared to the adjacent natural vegetation. Besides the effect of propagule pressure, altered disturbance regime and soil processes, one of the reasons given for the strong influence of mountain roads on species distributions is a significantly altered microclimate in the roadside compared to the adjacent vegetation, a direct consequence of the altered disturbance regime. However, the microclimatic differences between roadside and natural vegetation have rarely been quantified, particularly lacking global analyses, hampering a better understanding of their importance for mountain biodiversity. In this study, we analysed in-situ measured soil temperatures along mountain roads in seven mountain regions across the globe, in order to assess the impact of mountain roads on a range of bioclimatic variables across the elevational gradient. Our results undeniably show the importance of roadsides as unique microhabitats, even in heterogeneous mountain environments. In most regions, roadside soils had warmer maxima (3.95 {+/-} 2.35{degrees}C warmer) and colder minima (0.85 {+/-} 1.11 {degrees}C colder) than the soil in the adjacent vegetation, with higher frost risks in winter. Therefore, we recommend future research to incorporate the notion that the local microclimates created by mountain roads could play a critical role in species redistributions in space and time.

ecology↗