Biology subjects

Juravel, K.

Publications and source records attributed to Juravel, K..

4 recordsLinked to original sources

bioRxiv2026

An Integrative Taste Receptor Links pH and Amino Acids to Sugar Sensing in Bemisia tabaci

Phloem-feeding insects execute complex behavioral decisions to secure essential nutrients from a diet characterized by nitrogen scarcity and severe osmotic pressure due to high sucrose concentrations. We investigated the sensory mechanisms underlying these decisions in the phloem-feeding whitefly Bemisia tabaci. We demonstrate that the sweet taste receptor BtabGR1, expressed in mouthpart and gut tissues, integrates three environmental chemical cues: sucrose concentration, the presence of the essential amino acid arginine, and pH values. Arginine is a pH-dependent positive modulator of sucrose sensing, increasing receptor responses nearly fourfold under apoplast-like conditions and more than doubling the receptor responses in the gut luminal environment. Insects show a strong feeding preference for arginine-containing diets in dual-choice bioassays, with markedly higher intake when arginine is present. RNAi-mediated silencing of BtabGR1 disrupt intake regulation, leading to increased honeydew excretion. These findings suggest a putative link between arginine and the BtabGR1 receptor in regulating both feeding-site evaluation and diet ingestion. Furthermore, the ability to integrate three distinct environmental cues makes BtabGR1 one of the most complex interdependent sensory systems described for a single insect chemoreceptor.

physiology↗

bioRxiv2021

Improved resolution of recalcitrant nodes in the animal phylogeny through the analysis of genome gene content and morphology

An accurate phylogeny of animals is needed to clarify their evolution, ecology, and impact on shaping the biosphere. Although datasets of several hundred thousand amino acids are nowadays routinely used to test phylogenetic hypotheses, key deep nodes in the metazoan tree remain unresolved: the root of animals, the root of Bilateria, and the monophyly of Deuterostomia. Instead of using the standard approach of amino acid datasets, we performed analyses of newly assembled genome gene content and morphological datasets to investigate these recalcitrant nodes in the phylogeny of animals. We explored extensively the choices for assembling the genome gene content dataset and model choices of morphological analyses. Our results are robust to these choices and provide additional insights into the early evolution of animals, they are consistent with sponges as the sister group of all the other animals, the worm-like bilaterian lineage Xenacoelomorpha as the sister group of the other Bilateria, and tentatively support monophyletic Deuterostomia.

evolutionary biology↗

bioRxiv2020

The genomic basis of animal origins: a chromosomal perspective from the sponge Ephydatia muelleri

The genomes of non-bilaterian metazoans are key to understanding the molecular basis of early animal evolution. However, a full comprehension of how animal-specific traits such as nervous systems arose is hindered by the scarcity and fragmented nature of genomes from key taxa, such as Porifera. Ephydatia muelleri is a freshwater sponge found across the northern hemisphere. Here we present its 326 Mb genome, assembled to high contiguity (N50: 9.88 Mb) with 23 chromosomes on 24 scaffolds. Our analyses reveal a metazoan-typical genome architecture, with highly shared synteny across Metazoa, and suggest that adaptation to the extreme temperatures and conditions found in freshwater often involves gene duplication. The pancontinental distribution and ready laboratory culture of E. muelleri make this a highly practical model system, which with RNAseq, DNA methylation and bacterial amplicon data spanning its development and range allows exploration of genomic changes both within sponges and in early animal evolution.

evolutionary biology↗

bioRxiv2018

To B or not to B: Arsenophonus as a source of B-vitamins in whiteflies.

1Insect lineages feeding on nutritionally restricted diets such as phloem, xylem, or blood, were able to diversify by acquiring bacterial species that complemented the missing nutrients. These bacteria, considered obligate/primary endosymbionts, share a long evolutionary history with their hosts. In some cases, however, these endosymbionts are not able to fulfill all the nutritional requirements of their host, driving the acquisition of additional symbiotic species. Whiteflies, which feed on phloem, established an obligate relationship with Candidatus Portiera aleyrodidarum, who provides essential amino acids and carotenoids to the host. As many Whiteflies species harbor additional endosymbionts, they could provide their hosts with missing nutrients. To test this hypothesis, genomes of several endosymbionts from the whiteflies Aleurodicus dispersus, A. floccissimus and Trialeurodes vaporariorum were sequenced and analyzed. All three species were found to harbor an endosymbiont from the genus Arsenophonus, and the two former also host Wolbachia. A comparative analysis of the three Arsenophonus genomes revealed that although all of them are capable of synthesizing B-vitamins and cofactors, such as pyridoxal, riboflavin, or folate, their genomes and phylogenetic relationship vary greatly. Arsenophonus of A. floccissimus and T. vaporariorum belong to the same clade and display characteristics of facultative endosymbionts, such as large genomes (3 Mb) with thousands of genes, many pseudogenes, intermediate GC content, and mobile genetic elements (MGEs). In contrast, Arsenophonus of A. dispersus belongs to a different lineage and displays the characteristics of a primary endosymbiont, such as a reduced genome (670 kb) with 400 genes, 32% GC content, and no MGEs. However, the presence of 274 pseudogenes suggests that this symbiotic association is more recent than other reported hemipterans primary endosymbionts. Arsenophonus of A. dispersus gene repertoire is completely integrated in the symbiotic consortia, and the biosynthesis of most vitamins occurs in shared pathways with its host. In addition, Wolbachia have also retained the ability to produce riboflavin, FAD, and folate, and may have a nutritional contribution. Taken together, our results show that Arsenophonus have a pivotal place in whiteflies nutrition by their ability to produce B-vitamins, even if they diverge and/or go through a genome reduction process.

microbiology↗