67 research outputs found
Strigolactone biosynthesis and signaling in plant development.
Strigolactones (SLs), first identified for their role in parasitic and symbiotic interactions in the rhizosphere, constitute the most recently discovered group of plant hormones. They are best known for their role in shoot branching but, more recently, roles for SLs in other aspects of plant development have emerged. In the last five years, insights into the SL biosynthetic pathway have also been revealed and several key components of the SL signaling pathway have been identified. Here, and in the accompanying poster, we summarize our current understanding of the SL pathway and discuss how this pathway regulates plant development
Can Peto\u27s paradox be used as the null hypothesis to identify the role of evolution in natural resistance to cancer? A critical review
BACKGROUND: Carcinogenesis affects not only humans but almost all metazoan species. Understanding the rules driving the occurrence of cancers in the wild is currently expected to provide crucial insights into identifying how some species may have evolved efficient cancer resistance mechanisms. Recently the absence of correlation across species between cancer prevalence and body size (coined as Peto\u27s paradox) has attracted a lot of attention. Indeed, the disparity between this null hypothesis, where every cell is assumed to have an identical probability to undergo malignant transformation, and empirical observations is particularly important to understand, due to the fact that it could facilitate the identification of animal species that are more resistant to carcinogenesis than expected. Moreover it would open up ways to identify the selective pressures that may be involved in cancer resistance. However, Peto\u27s paradox relies on several questionable assumptions, complicating the interpretation of the divergence between expected and observed cancer incidences. DISCUSSIONS: Here we review and challenge the different hypotheses on which this paradox relies on with the aim of identifying how this null hypothesis could be better estimated in order to provide a standard protocol to study the deviation between theoretical/theoretically predicted and observed cancer incidence. We show that due to the disproportion and restricted nature of available data on animal cancers, applying Peto\u27s hypotheses at species level could result in erroneous conclusions, and actually assume the existence of a paradox. Instead of using species level comparisons, we propose an organ level approach to be a more accurate test of Peto\u27s assumptions. SUMMARY: The accuracy of Peto\u27s paradox assumptions are rarely valid and/or quantifiable, suggesting the need to reconsider the use of Peto\u27s paradox as a null hypothesis in identifying the influence of natural selection on cancer resistance mechanisms
Large-scale signatures of unconsciousness are consistent with a departure from critical dynamics
Loss of cortical integration and changes in the dynamics of
electrophysiological brain signals characterize the transition from wakefulness
towards unconsciousness. The common mechanism underlying these observations
remains unknown. In this study we arrive at a basic model, which explains these
empirical observations based on the theory of phase transitions in complex
systems. We studied the link between spatial and temporal correlations of
large-scale brain activity recorded with functional magnetic resonance imaging
during wakefulness, propofol-induced sedation and loss of consciousness, as
well as during the subsequent recovery. We observed that during unconsciousness
activity in frontal and thalamic regions exhibited a reduction of long-range
temporal correlations and a departure of functional connectivity from the
underlying anatomical constraints. These changes in dynamics and
anatomy-function coupling were correlated across participants, suggesting that
temporal complexity and an efficient exploration of anatomical connectivity are
inter-related phenomena. A model of a system exhibiting a phase transition
reproduced our findings, as well as the diminished sensitivity of the cortex to
external perturbations during unconsciousness. This theoretical framework
unifies different empirical observations about brain activity during
unconsciousness and predicts that the principles we identified are universal
and independent of the causes behind loss of awareness.Comment: to appear in Journal of the Royal Society Interfac
High-Resolution Solid-State Oxygen-17 NMR of Actinide-Bearing Compounds: An Insight into the 5f Chemistry
Two different methods to assess sympathetic tone during general anesthesia lead to different findings.
Noxious stimulation influences the autonomic nervous system activity. Sympathetic tone monitoring is currently used to assess the adequacy of the balance between nociception and anti-nociception during general anesthesia. The Surgical Plethysmographic Index (SPI) and the EBMi software (Custos(c)) are commercial devices that use different algorithms to measure it. We aimed at determining whether those devices provide similar information during routine surgical procedures under general anesthesia. Data acquired during a previously published study in patients undergoing surgery under general anesthesia were retrospectively analyzed and passed through the EBMi software. The occurrence of EBMi alarms of increased sympathetic tone was compared to the occurrence of SPI values >/= 60, a commonly recommended intraoperative SPI threshold. Trends in classical parameters of sympathetic tone during the 5 min preceding a SPI >/= 60, namely blood pressure, heart rate, and plethysmographic pulse amplitude were assessed. SPI >/= 60 episodes (n = 307) were more frequent than EBMi alerts (n = 240). Approximately 70% of EBMi alerts occurred during periods where the SPI was below 60. Among all episodes of SPI >/= 60, absence of any EBMi alerts was much more frequent than the inverse. A majority, but not all SPI >/= 60 episodes were consistently preceded by an increase in heart rate and/or a decrease in pulse amplitude. Blood pressure did not significantly change before SPI >/= 60. Longer SPI >/= 60 episodes were associated with lower anti-nociception anesthetic regimen. Different methods of sympathetic tone assessment during general anesthesia provide conflicting information. Prospective studies should be undertaken to clarify the clinical indications of both techniques
Polymorphism of metallothionein genes in the Pacific oyster Crassostrea gigas as a biomarker of response to metal exposure
International audienc
Analyse de la mise en place du système foliaire et des organes reproducteurs du maïs en fonction de la contrainte hydrique
National audienc
LeMoan_4_pops_all_samples_anchovy_working_dataset_MAC2_1SNPperRAD
The global SNP dataset used in NewHybrids analysis and in the PCA analysis containing hybrids (Figure 1A). The VCF file contains 5638 SNPs typed in 128 individuals. The minor allele count (MAC) threshold is 2 and only one SNP per RAD was kept
LeMoan_Atlantic_anchovy_working_dataset_MAC1_1SNPperRAD
The Atlantic subdataset containing 5260 SNPs typed 41 non-admixed individuals that were classified either as pure marine (30 PM) or pure coastal (11 PC) ecotypes using a 95% assignment probability threshold in NewHybrids. The minor allele count (MAC) threshold is 1 and only one SNP per RAD was kept
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