In Vitro Mutational and Bioinformatics Analysis of the M71 Odorant Receptor and Its Superfamily

We performed an extensive mutational analysis of the canonical mouse odorant receptor (OR) M71 to determine the properties of ORs that inhibit plasma membrane trafficking in heterologous expression systems. We employed the use of the M71::GFP fusion protein to directly assess plasma membrane localization and functionality of M71 in heterologous cells in vitro or in olfactory sensory neurons (OSNs) in vivo. OSN expression of M71::GFP show only small differences in activity compared to untagged M71. However, M71::GFP could not traffic to the plasma membrane even in the presence of proposed accessory proteins RTP1S or mβ2AR. To ask if ORs contain an internal “kill sequence”, we mutated ~15 of the most highly conserved OR specific amino acids not found amongst the trafficking non-OR GPCR superfamily; none of these mutants rescued trafficking. Addition of various amino terminal signal sequences or different glycosylation motifs all failed to produce trafficking. The addition of the amino and carboxy terminal domains of mβ2AR or the mutation Y289A in the highly conserved GPCR motif NPxxY does not rescue plasma membrane trafficking. The failure of targeted mutagenesis on rescuing plasma membrane localization in heterologous cells suggests that OR trafficking deficits may not be attributable to conserved collinear motifs, but rather the overall amino acid composition of the OR family. Thus, we performed an in silico analysis comparing the OR and other amine receptor superfamilies. We find that ORs contain fewer charged residues and more hydrophobic residues distributed throughout the protein and a conserved overall amino acid composition. From our analysis, we surmise that it may be difficult to traffic ORs at high levels to the cell surface in vitro, without making significant amino acid modifications. Finally, we observed specific increases in methionine and histidine residues as well as a marked decrease in tryptophan residues, suggesting that these changes provide ORs with special characteristics needed for them to function in olfactory neurons

In Vitro Mutational Analysis of the β2 Adrenergic Receptor, an In Vivo Surrogate Odorant Receptor

Many G-protein coupled receptors (GPCRs), such as odorant receptors (ORs), cannot be characterized in heterologous cells because of their difficulty in trafficking to the plasma membrane. In contrast, a surrogate OR, the GPCR mouse β2-adrenergic-receptor (mβ2AR), robustly traffics to the plasma membrane. We set out to characterize mβ2AR mutants in vitro for their eventual use in olfactory axon guidance studies. We performed an extensive mutational analysis of mβ2AR using a Green Fluorescent Protein-tagged mβ2AR (mβ2AR::GFP) to easily assess the extent of its plasma membrane localization. In order to characterize mutants for their ability to successfully transduce ligand-initiated signal cascades, we determined the half maximal effective concentrations (EC50) and maximal response to isoprenaline, a known mβ2AR agonist. Our analysis reveals that removal of amino terminal (Nt) N-glycosylation sites and the carboxy terminal (Ct) palmitoylation site of mβ2AR do not affect its plasma membrane localization. By contrast, when both the Nt and Ct of mβ2AR are replaced with those of M71 OR, plasma membrane trafficking is impaired. We further analyze three mβ2AR mutants (RDY, E268A, and C327R) used in olfactory axon guidance studies and are able to decorrelate their plasma membrane trafficking with their capacity to respond to isoprenaline. A deletion of the Ct prevents proper trafficking and abolishes activity, but plasma membrane trafficking can be selectively rescued by a Tyrosine to Alanine mutation in the highly conserved GPCR motif NPxxY. This new loss-of-function mutant argues for a model in which residues located at the end of transmembrane domain 7 can act as a retention signal when unmasked. Additionally, to our surprise, amongst our set of mutations only Ct mutations appear to lower mβ2AR EC50s revealing their critical role in G-protein coupling. We propose that an interaction between the Nt and Ct is necessary for proper folding and/or transport of GPCRs

The Arginine Methyltransferase Carm1 is Necessary for Heart Development

To discover genes implicated in human congenital disorders, we performed ENU mutagenesis in the mouse and screened for mutations affecting embryonic development. In this work we report defects of heart development in mice homozygous for a mutation of Coactivator-associated Arginine Methyltransferase 1 (Carm1). While Carm1 has been extensively studied, it has never been previously associated with a role in heart development. Phenotype analysis combining histology and micro-computed tomography (micro-CT) imaging shows a range of cardiac defects. Most notably, many affected mid-gestation embryos appear to have cardiac rupture and hemorrhaging in the thorax. Mice that survive to late gestation show a variety of cardiac defects, including Ventricular Septal Defects (VSDs), Double Outlet Right Ventricle (DORV), and Persistent Truncus Arteriosus (PTA). Transcriptome analyses of the mutant embryos by mRNA-seq reveal the perturbation of several genes involved in cardiac morphogenesis and muscle development and function. In addition, we observe the mis-localization of cardiac neural crest cells at E12.5 in the outflow tract. The cardiac phenotype of Carm1 mutant embryos is similar to that of Pax3 null mutants, and PAX3 is a putative target of CARM1. However, our analysis does not support the hypothesis that developmental defects in Carm1 mutant embryos are primarily due to a functional defect of PAX3

Community-Level Responses to Iron Availability in Open Ocean Plankton Ecosystems

Predicting responses of plankton to variations in essential nutrients is hampered by limited in situ measurements, a poor understanding of community composition, and the lack of reference gene catalogs for key taxa. Iron is a key driver of plankton dynamics and, therefore, of global biogeochemical cycles and climate. To assess the impact of iron availability on plankton communities, we explored the comprehensive bio-oceanographic and bio-omics data sets from Tara Oceans in the context of the iron products from two state-of-the-art global scale biogeochemical models. We obtained novel information about adaptation and acclimation toward iron in a range of phytoplankton, including picocyanobacteria and diatoms, and identified whole subcommunities covarying with iron. Many of the observed global patterns were recapitulated in the Marquesas archipelago, where frequent plankton blooms are believed to be caused by natural iron fertilization, although they are not captured in large-scale biogeochemical models. This work provides a proof of concept that integrative analyses, spanning from genes to ecosystems and viruses to zooplankton, can disentangle the complexity of plankton communities and can lead to more accurate formulations of resource bioavailability in biogeochemical models, thus improving our understanding of plankton resilience in a changing environment

A Strategy for Direct Mapping and Identification of Mutations by Whole-Genome Sequencing

Mutant screens have proven powerful for genetic dissection of a myriad of biological processes, but subsequent identification and isolation of the causative mutations are usually complex and time consuming. We have made the process easier by establishing a novel strategy that employs whole-genome sequencing to simultaneously map and identify mutations without the need for any prior genetic mapping

Effet de la complexité visuelle du packaging sur l’attention portée à la marque

International audienceDepuis plusieurs années, le nombre d’informations présentes sur les packagings de nombreux produits augmente régulièrement. Nous n’avons que peu de connaissances sur les conséquences d’un environnement de plus en plus saturé d’informations sur l’attention portée à la marque. Dans ce travail est examinée l’influence de la complexité du packaging sur l’attention portée par le consommateur au packaging et à la marque lors du choix d’un produit. En utilisant un dispositif d’oculométrie (eye-tracking), nos résultats montrent que l’augmentation du nombre d’unités d’information présentes sur le facing de deux catégories de produits alimentaires (jus d’orange et chocolat en tablettes) accroît l’attention visuelle dévolue au packaging, sans pour autant altérer l’attention portée à la marque. Mots-clés : Packaging, attention visuelle, eye-tracking, unités d’information

Ecological succession of pico- and nanophytoplankton in a coastal bay of NW Mediterranean sea

International audienceThe long-term evolution of pico- and nanophytoplanktonic communities in two coastal contrasting sites from the bay of Toulon was studied using monthly flow cytometry analyses during a seven-year period. Results highlighted higher abundance of both pico- and nanophytoplanktonic communities in the more eutrophic site (i. e. the Little Bay). Moreover, even if both sites were widely dominated by Synechococcus spp. population, it represented more than 90% of the population during summer in the Large Bay. Using diversity indices and rank frequency diagrams to study ecological successions in both sites, communities from the Little Bay (the most polluted site) appeared, paradoxically, as more diversified and more mature than that from the Large Bay. Communities from the Large Bay appeared as less diversified and juvenile linked to the dominance of Synechococcus spp. The complementarity of diversity indices and rank frequency diagram was revealed in this present work

Ecological succession of pico- and nanophytoplankton in a coastal bay of NW Mediterranean sea

International audienceThe long-term evolution of pico- and nanophytoplanktonic communities in two coastal contrasting sites from the bay of Toulon was studied using monthly flow cytometry analyses during a seven-year period. Results highlighted higher abundance of both pico- and nanophytoplanktonic communities in the more eutrophic site (i. e. the Little Bay). Moreover, even if both sites were widely dominated by Synechococcus spp. population, it represented more than 90% of the population during summer in the Large Bay. Using diversity indices and rank frequency diagrams to study ecological successions in both sites, communities from the Little Bay (the most polluted site) appeared, paradoxically, as more diversified and more mature than that from the Large Bay. Communities from the Large Bay appeared as less diversified and juvenile linked to the dominance of Synechococcus spp. The complementarity of diversity indices and rank frequency diagram was revealed in this present work

Overview of literature monitoring practice of clinical trials vigilance units in French institutional sponsors - A study from the REVISE working group

International audienceINTRODUCTION: The evaluation of clinical trial (CT) safety is the main task of CT vigilance units. In addition to the management of adverse events, the units must review the literature to identify information that may impact the benefit-risk assessment of studies. In this survey, we investigated the literature monitoring (LM) activity of French Institutional Vigilance Units (IVU) from the working group "REflexion sur la VIgilance et la SEcurite des essais cliniques" (REVISE). MATERIAL AND METHODS: We sent a questionnaire of 26 questions, divided into four themes, to the 60 IVU: (1) Presentation of the IVU and the LM activity; (2) Used sources, queries and criteria for selecting articles; (3) Valuation of the LM and (4) Practical organisation. RESULTS: Of the 27 IVU that responded to the questionnaire, 85% of them carried out LM. This was mainly provided by medical staff to improve general knowledge (83%), to detect Adverse Reactions (AR) not listed in the reference documents (70%) and to detect new safety information (61%). Due to lack of time, staff, available recommendations and sources, only 21% of IVU conducted LM for all CT. On average, units reported four sources: ANSM information (96%), PubMed database (83%), EMA alerts (57%) and the subscription to APM international (48%). The LM had an impact on the CT of 57% of the IVU such as changing the conditions of a study (39%) or suspending a study (22%). DISCUSSION/CONCLUSION: LM is an important but time-consuming activity with heterogeneous practices. According to the results of this survey, we proposed seven ways to improve this practice: (1) Target the highest risk CT; (2) Refine the PubMed queries; (3) Use other tools; (4) Create a decision flowchart for the selection of PubMed articles; (5) Improve training; (6) Value the activity and (7) Outsource the activity