The power of proximity: mechanisms and biological roles of transvection.

The phenomenon of transvection, defined as a proximity-dependent interallelic interaction, has been observed in the context of complementation between mutant alleles for numerous Drosophila genes. Cases of transvection-like phenomena have also been observed in other species, including mammals. However, the potential contribution of transvection to wild-type gene regulation and the underlying mechanisms remain uncertain.

Regulatory evolution tuning pigmentation intensity quantitatively in .

Quantitative variation in attributes such as color, texture, or stiffness dominates morphological diversification. It results from combinations of alleles at many Mendelian loci. Here, we identify an additional source of quantitative variation among species, continuous evolution in a gene regulatory region.

Increased sugar valuation contributes to the evolutionary shift in egg-laying behavior of the fruit pest Drosophila suzukii.

Behavior evolution can promote the emergence of agricultural pests by changing their ecological niche. For example, the insect pest Drosophila suzukii has shifted its oviposition (egg-laying) niche from fermented fruits to ripe, non-fermented fruits, causing significant damage to a wide range of fruit crops worldwide. We investigate the chemosensory changes underlying this evolutionary shift and ask whether fruit sugars, which are depleted during fermentation, are important gustatory cues that direct D.

Segmentation and Quantitative Analysis of Epithelial Tissues.

Epithelial tissues regulate exchanges with the environment. They are highly dynamic and can acquire virtually any shape. At the cellular level, they are composed of cells tightly connected by junctions.

Relevance and mechanisms of transvection.

Transvection, the functional interaction between homologous alleles, was first described in Drosophila in the 1950's. While transvection has been documented in a growing list of genes, using mutant alleles or synthetic constructs, in Drosophila and other organisms, the extent of its relevance to gene expression in physiological conditions has remained questionable. The molecular mechanisms underlying transvection are still largely unexplored, although hints suggest a link with the general machinery that controls the genome organization in the nucleus.

Transvection regulates the sex-biased expression of a fly X-linked gene.

Sexual dimorphism in animals results from sex-biased gene expression patterns. These patterns are controlled by genetic sex determination hierarchies that establish the sex of an individual. Here we show that the male-biased wing expression pattern of the gene , located on the X chromosome, is independent of the fly sex determination hierarchy.

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

Epithelia 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.

Regulatory encoding of quantitative variation in spatial activity of a enhancer.

Developmental enhancers control the expression of genes prefiguring morphological patterns. The activity of an enhancer varies among cells of a tissue, but collectively, expression levels in individual cells constitute a spatial pattern of gene expression. How the spatial and quantitative regulatory information is encoded in an enhancer sequence is elusive.

Near-chromosome level genome assembly of the fruit pest Drosophila suzukii using long-read sequencing.

Over the past decade, the spotted wing Drosophila, Drosophila suzukii, has invaded Europe and America and has become a major agricultural pest in these areas, thereby prompting intense research activities to better understand its biology. Two draft genome assemblies already exist for this species but contain pervasive assembly errors and are highly fragmented, which limits their values. Our purpose here was to improve the assembly of the D.

Inherent privacy limitations of decentralized contact tracing apps.

Recently, there have been many efforts to use mobile apps as an aid in contact tracing to control the spread of the SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) (COVID-19 [coronavirus disease 2019]) pandemic. However, although many apps aim to protect individual privacy, the very nature of contact tracing must reveal some otherwise protected personal information. Digital contact tracing has endemic privacy risks that cannot be removed by technological means, and which may require legal or economic solutions.

A Whole-Genome Scan for Association with Invasion Success in the Fruit Fly Drosophila suzukii Using Contrasts of Allele Frequencies Corrected for Population Structure.

Evidence is accumulating that evolutionary changes are not only common during biological invasions but may also contribute directly to invasion success. The genomic basis of such changes is still largely unexplored. Yet, understanding the genomic response to invasion may help to predict the conditions under which invasiveness can be enhanced or suppressed.

Evolution: Remodelling Animal Body Plans, Gene by Gene.

Changes in Homeotic (Hox) gene regulation have long been thought to drive the evolution of animal body plans. Direct genetic evidence of their evolutionary role has, however, remained limited. A new study reveals how several mutations distributed across a gene network mask the phenotypic effects of a Hox gene's evolution.

Quantitative and Discrete Evolutionary Changes in the Egg-Laying Behavior of Single 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 to describe the elementary behavioral steps or microbehaviors that a single female fly undertakes prior to and during egg laying.

Evolution of Ovipositor Length in Drosophila suzukii Is Driven by Enhanced Cell Size Expansion and Anisotropic Tissue Reorganization.

Morphological diversity is dominated by variation in body proportion [1], which can be described with scaling relationships and mathematical equations, following the pioneering work of D'Arcy Thompson [2] and Julian Huxley [3]. Yet, the cellular processes underlying divergence in size and shape of morphological traits between species remain largely unknown [4-8]. Here, we compare the ovipositors of two related species, Drosophila melanogaster and D.

A short guide to insect oviposition: when, where and how to lay an egg.

Egg-laying behavior is one of the most important aspects of female behavior, and has a profound impact on the fitness of a species. As such, it is controlled by several layers of regulation. Here, we review recent advances in our understanding of insect neural circuits that control when, where and how to lay an egg.

The Genomic Basis of Color Pattern Polymorphism in the Harlequin Ladybird.

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.

Revisiting the developmental and cellular role of the pigmentation gene yellow in Drosophila using a tagged allele.

Pigmentation is a diverse and ecologically relevant trait in insects. Pigment formation has been studied extensively at the genetic and biochemical levels. The temporality of pigment formation during animal development, however, is more elusive.

Evolution of Multiple Sensory Systems Drives Novel Egg-Laying Behavior in the Fruit Pest Drosophila suzukii.

The rise of a pest species represents a unique opportunity to address how species evolve new behaviors and adapt to novel ecological niches [1]. We address this question by studying the egg-laying behavior of Drosophila suzukii, an invasive agricultural pest species that has spread from Southeast Asia to Europe and North America in the last decade [2]. While most closely related Drosophila species lay their eggs on decaying plant substrates, D.

Looking under the lamp post: neither fruitless nor doublesex has evolved to generate divergent male courtship in Drosophila.

How do evolved genetic changes alter the nervous system to produce different patterns of behavior? We address this question using Drosophila male courtship behavior, which is innate, stereotyped, and evolves rapidly between species. D. melanogaster male courtship requires the male-specific isoforms of two transcription factors, fruitless and doublesex.

Emergence and diversification of fly pigmentation through evolution of a gene regulatory module.

The typical pattern of morphological evolution associated with the radiation of a group of related species is the emergence of a novel trait and its subsequent diversification. Yet the genetic mechanisms associated with these two evolutionary steps are poorly characterized. Here, we show that a spot of dark pigment on fly wings emerged from the assembly of a novel gene regulatory module in which a set of pigmentation genes evolved to respond to a common transcriptional regulator determining their spatial distribution.

Smells like evolution: the role of chemoreceptor evolution in behavioral change.

In contrast to physiology and morphology, our understanding of how behaviors evolve is limited. This is a challenging task, as it involves the identification of both the underlying genetic basis and the resultant physiological changes that lead to behavioral divergence. In this review, we focus on chemosensory systems, mostly in Drosophila, as they are one of the best-characterized components of the nervous system in model organisms, and evolve rapidly between species.