Quantitative and Discrete Evolutionary Changes in the Egg-Laying Behavior of Single Drosophila Females

How a nervous system assembles and coordinates a suite of elementary behavioral steps into a complex behavior is not well understood. While often presented as a stereotyped sequence of events, even extensively studied behaviors such as fly courtship are rarely a strict repetition of the same steps in a predetermined sequence in time. We are focusing on oviposition, the act of laying an egg, in flies of the genus Drosophila to describe the elementary behavioral steps or microbehaviors that a single female fly undertakes prior to and during egg laying. We have analyzed the hierarchy and relationships in time of these microbehaviors in three closely related Drosophila species with divergent egg-laying preferences and uncovered cryptic differences in their behavioral patterns. Using high-speed imaging, we quantified in depth the oviposition behavior of single females of Drosophila suzukii, Drosophila biarmipes and Drosophila melanogaster in a novel behavioral assay. By computing transitions between microbehaviors, we identified a common ethogram structure underlying oviposition of all three species. Quantifying parameters such as relative time spent on a microbehavior and its average duration, however, revealed clear differences between species. In addition, we examined the temporal dynamics and probability of transitions to different microbehaviors relative to a central event of oviposition, ovipositor contact. Although the quantitative analysis highlights behavioral variability across flies, it reveals some interesting trends for each species in the mode of substrate sampling, as well as possible evolutionary differences. Larger datasets derived from automated video annotation will overcome this paucity of data in the future, and use the same framework to reappraise these observed differences. Our study reveals a common architecture to the oviposition ethogram of three Drosophila species, indicating its ancestral state. It also indicates that Drosophila suzukii’s behavior departs quantitatively and qualitatively from that of the outgroup species, in line with its known divergent ethology. Together, our results illustrate how a global shift in ethology breaks down in the quantitative reorganization of the elementary steps underlying a complex behavior

The genomic basis of color pattern polymorphism in the Harlequin ladybird

© 2018 The Authors Many animal species comprise discrete phenotypic forms. A common example in natural populations of insects is the occurrence of different color patterns, which has motivated a rich body of ecological and genetic research [1–6]. The occurrence of dark, i.e., melanic, forms displaying discrete color patterns is found across multiple taxa, but the underlying genomic basis remains poorly characterized. In numerous ladybird species (Coccinellidae), the spatial arrangement of black and red patches on adult elytra varies wildly within species, forming strikingly different complex color patterns [7, 8]. In the harlequin ladybird, Harmonia axyridis, more than 200 distinct color forms have been described, which classic genetic studies suggest result from allelic variation at a single, unknown, locus [9, 10]. Here, we combined whole-genome sequencing, population-based genome-wide association studies, gene expression, and functional analyses to establish that the transcription factor Pannier controls melanic pattern polymorphism in H. axyridis. We show that pannier is necessary for the formation of melanic elements on the elytra. Allelic variation in pannier leads to protein expression in distinct domains on the elytra and thus determines the distinct color patterns in H. axyridis. Recombination between pannier alleles may be reduced by a highly divergent sequence of ∼170 kb in the cis-regulatory regions of pannier, with a 50 kb inversion between color forms. This most likely helps maintain the distinct alleles found in natural populations. Thus, we propose that highly variable discrete color forms can arise in natural populations through cis-regulatory allelic variation of a single gene. More than 200 distinct color forms have been described in natural populations of the harlequin ladybird, Harmonia axyridis. Gautier et al. show that this variation is controlled by the transcription factor Pannier. Pannier is necessary to produce black pigment, and its expression pattern prefigures the coloration pattern in each color form

Origine évolutive de la segmentation chez les bilateriens (étude de la formation des segments chez l'annélide platynereis dumerilii)

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Enquête sur le Burning Mouth Syndrome auprès des chirurgiens dentistes

À la croisée de plusieurs disciplines médicales, le Burning Mouth Syndrome ou BMS est une affection relativement peu connue qui se manifeste par des douleurs au niveau de la cavité buccale sans signes cliniques ou biologiques. Son étiologie reste mal définie et est le sujet de nombreuses investigations dans des directions toutes aussi diverses. Afin de mieux appréhender cette pathologie, une enquête a été réalisée directement auprès des chirurgiens-dentistes lors du congrès de l'association dentaire française (ADF) 2010, qui avait pour objectif d'étudier l'état actuel de leurs savoirs sur le BMS. Nous avons distribué 301 questionnaires dont nous avons analysé les informations. Il en ressort qu'environ la moitié des praticiens connaissent cette pathologie mais sous différentes appellations.NANTES-BU Médecine pharmacie (441092101) / SudocNANTES-Bib.Odontologie (441092219) / SudocSudocFranceF

EPySeg: a coding-free solution for automated segmentation of epithelia using deep learning

International audienceEpithelia are dynamic tissues that self-remodel during their development. During morphogenesis, the tissue-scale organization of epithelia is obtained through a sum of individual contributions of the cells constituting the tissue. Therefore, understanding any morphogenetic event first requires a thorough segmentation of its constituent cells. This task, however, usually implies extensive manual correction, even with semi-automated tools. Here we present EPySeg, an open-source, coding-free software that uses deep learning to segment membrane-stained epithelial tissues automatically and very efficiently. EPySeg, which comes with a straightforward graphical user interface, can be used as a python package on a local computer, or on the cloud via Google Colab for users not equipped with deep-learning compatible hardware. By substantially reducing human input in image segmentation, EPySeg accelerates and improves the characterization of epithelial tissues for all developmental biologists

3D, laserscanning and geomorphological studies in Orgnac cave (Ardèche, France)

Recent laserscanning techniques can revisit the geomorphological analysis methods traditionally used in caves. Indeed, laser scanning offers very high resolution topography. Very large point clouds are acquired and after consolidation, meshing and processing, analyzes on the 3D models can be performed. This type of approach is particularly interesting in cavities where size or conservation issues are important. This is the case of Orgnac, a major French tourist cavity, the only cave ranked "Grand Site de France". Three examples of 3D geomorphology studies illustrate here the relevance of this approach. (1) The gigantic underground volumes did not allow direct observation of all parietal morphologies. A 3D reconstruction of the "Salles rouges" chamber permits the identification of bench-marks on the 3D model. These works give us a reconstitution of the sedimentary aggradations during Pliocene. (2) A forest of stalagmites tilted was protected for conservation reasons and access restrictions. Again, the construction of a 3D model and some informatics developments give us automatic mapping to study, in their environment, the geometrical characteristics of 140 stalagmites. Finally (3), a detrital fan is currently being excavated for archaeological studies. This excavation destroys irreparably a side of this unique underground archive. Site supervision by lidar offers at each stage of the search, a topography which is a very fine memory of the deposit. In addition, 3D reconstruction and analysis of sedimentary structures provides information about its genesis. Through the diversity of these three examples, we measure the value of this type of analysis on 3D model to better understand underground morphologies. The implementation of this approach in tourist cave also offers an additional opportunity: the scientific mediation to the public, eager for this type of 3D production with many possibilities of representation

The new animal phylogeny: Reliability and implications

DNA sequence analysis dictates new interpretation of phylogenic trees. Taxa that were once thought to represent successive grades of complexity at the base of the metazoan tree are being displaced to much higher positions inside the tree. This leaves no evolutionary “intermediates” and forces us to rethink the genesis of bilaterian complexity