Biology subjects

Finet, C.

Publications and source records attributed to Finet, C..

9 recordsLinked to original sources

bioRxiv2026

Cuticulome.org: a centralized database of proteins in arthropod cuticles

Cuticle proteins, especially the cuticular protein (CP) multigene family, are essential for the building, maintenance, and environmental adaptation of the arthropod exoskeleton. The extensive size of CP repertoire, which often represents 1-2% of the protein-coding genes, is a challenge. The discontinuation of previous centralized databases for CPs and the lack of consistent nomenclature in the field have hindered functional analyses and comparative studies. Here, we present Cuticulome.org (accessible at https://www.Cuticulome.org), a curated knowledgebase of proteins that are found in arthropod cuticles. Database entries include protein sequences, tissue and developmental stage specificity, and diverse functional annotations where available, while implementing a standardized nomenclature system to facilitate intra- and cross-species analyses. At Cuticulome.org, users can download complete taxon-specific cuticular proteomes, entire CP families, or build their own custom datasets defined by taxonomic, protein family, functional, or keyword-based criteria. Cuticulome.org also offers two integrated sequence analysis tools: miniBLAST, which allows users to identify putative orthologous CPs, and Cuticular Protein Classifier, which accurately classifies a protein sequence to an established CP family based on custom Hidden Markov Models. Together, these features establish Cuticulome.org as the new centralized resource for systematic analysis of cuticle proteins.

bioinformatics↗

bioRxiv2024

Calreticulin is required for cuticle deposition and trabeculae formation inside butterfly wing scale cells

Insect cuticle is normally deposited outside the plasma membrane of epidermal cells, making it unclear how cuticular pillars (trabeculae) are found inside butterfly wing scale cells. By co-labelling the cuticle and the plasma membrane, we found evidence that the plasma membrane invaginates towards the interior of the scale during development, and that chitin pillars form within these invaginations within the cell, but topologically outside it. Furthermore, we found that Calreticulin, a multifunctional protein, is essential for the formation of these trabeculae. This protein was found colocalized with chitin outside the cell membrane, as scales were developing, and its knockout led to loss of chitin pillars, disruption of other scale morphologies, and loss of pigmentation. Our results implicate this multifunctional protein in butterfly wing scale coloration and morphology.

developmental biology↗

bioRxiv2024

Ridge and crossrib height of butterfly wing scales is a toolbox for structural color diversity

The brightest and most vivid colors of butterflies usually originate from light reflecting off the cuticular scales that cover the wing membrane. These scales have an intricate architecture that consists of an upper layer, a grid of longitudinal ridges and transverse crossribs, connected to a lower lamina by pillars called trabeculae. Whereas the role of the lower lamina as a reflector has been well documented in simpler scales, this study unveils the role of the scales upper surface in generating or fine-tuning hue, brightness, and saturation. In the nymphalid Bicyclus anynana, we showed that changes in ridge and trabecula heights accompanied changes in hue of scales produced via artificial selection. We further found that this correlation between ridge height and hue can be generalized to 40 scale types from 35 species across butterfly families. By combining focused ion beam milling, microspectrophotometry, and optical modelling, we found that modifying the ridge height is sufficient to change ridge hue, notably in Morpho didius whose blue color was thought to be generated exclusively by lamella protruding from ridges, rather than ridge height. This study identifies the scales upper surface as a toolbox for structural color diversity in butterflies and proposes a geometrical model to predict color that unifies species with and without Morpho-type Christmas-tree ridges.

evolutionary biology↗

bioRxiv2021

Antennapedia regulates metallic silver wing scale development and cell shape in Bicyclus anynana butterflies

Butterfly wing scale cells can develop very intricate cuticular nanostructures that interact with light to produce structural colors including silvery hues, but the genetic basis of such nanostructures is mostly unexplored. Here, we first identified that optix is necessary for metallic scale development in the butterfly Bicyclus anynana. We then characterized different subtypes of wildtype metallic silver scales and addressed the function of five genes - apterous A, Ultrabithorax, doublesex, Antennapedia, and optix - in the differentiation of silver scales, at a single-cell resolution, by leveraging crispants that exhibited either ectopic gains or losses of silver scales. Wildtype silver scales were generally rounded and had low amounts of pigmentation, exhibiting a common ultrastructural modification for metallic broadband reflectance, i.e., an undulatory air layer enclosed by an upper and lower lamina. Our results indicated that the varying air layer thickness was the important parameter of the bilaminate scale for producing a broadband reflectance across visible wavelengths. While a single lamina of the appropriate thickness could also produce broadband colors, the bilaminate structure is advantageous as it increases the overall reflectivity. Crispant brown scales differed from wildtype silver scales via the loss of the continuous upper lamina, increased lower lamina thickness, and increased pigmentation. The reverse was seen when brown scales became silver. We identified Antennapedia and optix as high-level regulators in the network differentiating different silver scale subtypes and determining overall cell shape in both sexes. In addition, Antp exhibits a novel, post-embryonic role in the determination of ridge and crossrib orientation.

developmental biology↗

bioRxiv2021

DrosoPhyla: genomic resources for drosophilid phylogeny and systematics

The vinegar fly Drosophila melanogaster is a pivotal model for invertebrate development, genetics, physiology, neuroscience, and disease. The whole family Drosophilidae, which contains over 4000 species, offers a plethora of cases for comparative and evolutionary studies. Despite a long history of phylogenetic inference, many relationships remain unresolved among the groups and genera in the Drosophilidae. To clarify these relationships, we first developed a set of new genomic markers and assembled a multilocus data set of 17 genes from 704 species of Drosophilidae. We then inferred well-supported group and species trees for this family. Additionally, we were able to determine the phylogenetic position of some previously unplaced species. These results establish a new framework for investigating the evolution of traits in fruit flies, as well as valuable resources for systematics.

evolutionary biology↗

bioRxiv2020

The Evolution of Insect Metallothioneins

Metallothioneins (MTs) are a family of cysteine-rich metal-binding proteins that are important in the chelating and detoxification of toxic heavy metals. Until now, the short length and the low sequence complexity of MTs has hindered the possibility of any phylogenetic reconstruction, hampering the study of their evolution. To answer this longstanding question, we developed an iterative BLAST search pipeline that allowed us to build a unique dataset of more than 300 MT sequences in insects. By combining phylogenetics and synteny analysis, we reconstructed the evolutionary history of MTs in insects. We show that the MT content in insects has been shaped by lineage-specific tandem duplications from a single ancestral MT. Strikingly, we also uncovered a sixth MT, MtnF, in the model organism Drosophila melanogaster. MtnF evolves faster than other MTs and is characterized by a non-canonical length and higher cysteine content. Our methodological framework not only paves the way for future studies on heavy metal detoxification but also can allow us to identify other previously unidentified genes and other low complexity genomic features.

evolutionary biology↗

bioRxiv2019

Birth-and-death evolution of the fatty acyl-CoA reductase (FAR) gene family and diversification of cuticular hydrocarbon synthesis in Drosophila

The birth-and-death evolutionary model proposes that some members of a multigene family are phylogenetically stable and persist as a single copy over time whereas other members are phylogenetically unstable and undergo frequent duplication and loss. Functional studies suggest that stable genes are likely to encode essential functions, while rapidly evolving genes reflect phenotypic differences in traits that diverge rapidly among species. One such class of rapidly diverging traits are insect cuticular hydrocarbons (CHCs), which play dual roles in chemical communications as short-range recognition pheromones as well as protecting the insect from desiccation. Insect CHCs diverge rapidly between related species leading to ecological adaptation and/or reproductive isolation. Because the CHC and essential fatty acid biosynthetic pathways share common genes, we hypothesized that genes involved in the synthesis of CHCs would be evolutionary unstable, while those involved in fatty acid-associated essential functions would be evolutionary stable. To test this hypothesis, we investigated the evolutionary history of the fatty acyl-CoA reductases (FARs) gene family that encodes enzymes in CHC synthesis. We compiled a unique dataset of 200 FAR proteins across 12 Drosophila species. We uncovered a broad diversity in FAR content which is generated by gene duplications, subsequent gene losses, and alternative splicing. We also show that FARs expressed in oenocytes and presumably involved in CHC synthesis are more unstable than FARs from other tissues. We suggest that a comparative approach investigating the birth-and-death evolution of gene families can identify candidate genes involved in rapidly diverging traits between species.

evolutionary biology↗

bioRxiv2018

Actomyosin-driven tension at compartmental boundaries orients cell division independently of cell geometry in vivo

During animal development, planar polarization of the actomyosin cytoskeleton underlies key morphogenetic events such as axis extension and boundary formation. Actomyosin is enriched along compartment boundaries during segmentation of the Drosophila embryo, forming supracellular contractile cables that keep cells segregated at boundaries. Here, we show that these contractile actomyosin cables bias the orientation of division in cells in contact with compartment boundaries. By decreasing actomyosin cable tension locally using laser ablation or, conversely ectopically increasing tension using laser wounding, we demonstrate that localised subcellular force is necessary and sufficient to orient mitoses in vivo. Moreover this bias is independent of cell geometry and involves capture of the spindle pole by the actomyosin cortex.

developmental biology↗

bioRxiv2018

The genome of the water strider Gerris buenoi reveals expansions of gene repertoires associated with adaptations to life on the water

The semi-aquatic bugs conquered water surfaces worldwide and occupy ponds, streams, lakes, mangroves, and even open oceans. As such, they inspired a range of scientific studies from ecology and evolution to developmental genetics and hydrodynamics of fluid locomotion. However, the lack of a representative water strider genome hinders thorough investigations of the mechanisms underlying the processes of adaptation and diversification in this group. Here we report the sequencing and manual annotation of the Gerris buenoi (G. buenoi) genome, the first water strider genome to be sequenced so far. G. buenoi genome is about 1 000Mb and the sequencing effort recovered 20 949 predicted protein-coding genes. Manual annotation uncovered a number of local (tandem and proximal) gene duplications and expansions of gene families known for their importance in a variety of processes associated with morphological and physiological adaptations to water surface lifestyle. These expansions affect key processes such as growth, vision, desiccation resistance, detoxification, olfaction and epigenetic components. Strikingly, the G. buenoi genome contains three Insulin Receptors, a unique case among metazoans, suggesting key changes in the rewiring and function of the insulin pathway. Other genomic changes include wavelength sensitivity shifts in opsin proteins likely in association with the requirements of vision in water habitats. Our findings suggest that local gene duplications might have had an important role during the evolution of water striders. These findings along with the G. buenoi genome open exciting research opportunities to understand adaptation and genome evolution of this unique hemimetabolous insect.

genomics↗