Biology subjects

Rahioui, I.

Publications and source records attributed to Rahioui, I..

6 recordsLinked to original sources

bioRxiv2026

Neprilysin 1 in the Mushroom Body controls Feeding behavior by regulating SIFamide levels in Drosophila melanogaster

Feeding-related behavior in Drosophila melanogaster encompasses olfactory and gustatory detection of odors, foraging, and food intake. In Drosophila melanogaster, the neuropeptide SIFamide (SIFa), has been shown to integrate hunger signals to promote feeding in Drosophila and is considered a central regulator of mutually exclusive behavioral states. Here, we identify the mushroom bodies as a key downstream circuit of SIFamidergic neurons for regulation of food-seeking and feeding. Furthermore, we show that mushroom bodies are not merely downstream effectors but actively shape SIFamidergic signaling through the peptidase Neprilysin 1 for which SIFamide is a substrate. Thus, SIFa signaling is embedded within a feedforward-feedback circuit that couples internal state to the selection and execution of feeding behavior. We propose that the distinct neuronal subtypes postsynaptic to the elaborately arborized SIFamidergic neurons define discrete neuronal subroutines that differentially control the mutually exclusive behaviors related to sexual reproduction, sleep and feeding. Our findings reveal an evolutionary ancient peptidergic system that is modified by recruitment of novel genes for the flexible control of distinct behavioral programs and feeding strategies.

animal behavior and cognition↗

bioRxiv2025

Liver FGF21 mediates sex-specific adaptation to juvenile protein malnutrition

Dietary protein sufficiency during childhood is essential for healthy growth and tissue development. Chronic protein deficiency leads to stunting, height-for-age more than two standard deviations below the median, and affects 149 million children under five (https://www.who.int/publications/i/item/9789240073791). Linear growth is governed by the somatotropic axis, wherein pituitary growth hormone (GH) stimulates hepatic insulin-like growth factor 1 (IGF-1) to promote bone elongation1. Although boys are consistently more stunted than girls across populations (ranging from 18% to 45%)2,3, mechanisms underlying this apparent resilience remain unclear. Rodent studies suggest that the protein-to-carbohydrate ratio modulates life-history traits such as metabolism, lifespan, and reproduction, with evidence of sex-dependent sensitivity4,5. Whether such dimorphism reflects coordinated developmental adaptations in response to protein scarcity, particularly in females, has not been fully explored. Here, we show that juvenile dietary protein restriction causes sexually dimorphic adaptations with pronounced stunting in males and delayed reproductive maturation in females. Using liver-specific deletion, we identify fibroblast growth factor 21 (FGF21) as a sex-specific hepatic regulator of female somatic growth and reproductive development, revealing a dimorphic endocrine adaptation to early-life protein scarcity. Our findings position FGF21 as a critical physiological checkpoint coordinating growth and reproductive timing in response to nutritional stress.

physiology↗

bioRxiv2022

Diet as a major driver of endosymbiont proliferation in cereal weevils

Nutritional symbioses between insects and intracellular bacteria (endosymbionts) are a major force of adaptation, allowing animals to colonize nutrient-poor ecological niches. Many beetles feeding on tyrosine-poor substrates rely on a surplus of aromatic amino acids produced by bacterial endosymbionts. This surplus of aromatic amino acids is crucial for the biosynthesis of a thick exoskeleton, the cuticle, which is made of a matrix of chitin with proteins and pigments built from tyrosine-derived molecules, providing an important defensive barrier against biotic and abiotic stress. Other endosymbiont-related advantages for beetles include faster development and improved fecundity. The association between Sitophilus oryzae and Sodalis pierantonius endosymbiont represents a unique case study among beetles: endosymbionts undergo an exponential proliferation in young adults concomitant with the cuticle tanning, then they are fully eliminated. While endosymbiont clearance, as well as total endosymbiont titer, are host-controlled processes, the mechanism triggering endosymbiont exponential proliferation remains poorly understood. Here, we show that endosymbiont exponential proliferation relies on host carbohydrate intake, unlike the total endosymbiont titer or the endosymbiont clearance, which are under host genetic control. Remarkably, insect fecundity was preserved, and the cuticle tanning was achieved, even when endosymbiont exponential proliferation was experimentally blocked, except in the context of a severely unbalanced diet. Moreover, a high endosymbiont titer coupled with nutrient shortage, dramatically impacted host survival, revealing possible environment-dependent disadvantages for the host, likely due to the high energy cost of exponentially proliferating endosymbionts. Abstract ImportanceBeetles thriving on tyrosine-poor diet sources often develop mutualistic associations with endosymbionts able to synthesize aromatic amino acids. This surplus of aromatic amino acids is used to reinforce the insects protective cuticle. An exceptional feature of the Sitophilus oryzae / Sodalis pierantonius interaction is the exponential increase in endosymbiotic titer observed in young adult insects, in concomitance with cuticle biosynthesis. Here, we show that host carbohydrate intake triggers endosymbiont exponential proliferation, even in conditions that lead to the detriment of the host survival. In addition, when hosts thrive on a balanced diet, endosymbiont proliferation is dispensable for several host fitness traits. The endosymbiont exponential proliferation is therefore dependent on the nutritional status of the host, and its consequences on host cuticle biosynthesis and survival depend on food quality and availability.

evolutionary biology↗

bioRxiv2021

The aphid BCR4 structure and activity uncover a new defensin peptide superfamily

Aphids (Hemiptera: Aphidoidea) are among the most injuring insects for agricultural plants and their management is a great challenge in agronomical research. A new class of proteins, called Bacteriocyte-specific Cysteine-Rich (BCR), provides an alternative to chemical insecticides for pest control. BCRs have been initially identified in the pea aphid Acyrthosiphon pisum. They are small disulfide bond-rich proteins expressed exclusively in aphid bacteriocytes, the insect derived cells that host intracellular symbiotic bacteria. Here, we show that one out of the A. pisum BCRs, BCR4, displays an outstanding insecticidal activity against the pea aphid, impairing insect survival and nymphal growth, providing evidence for its potential use as a new biopesticides. Our comparative genomics and phylogenetic analysis indicate that BCRs seem restricted to the aphid lineage. The 3D structure of the BCR4 reveals that this peptide belongs to a yet unknown structural class of peptides and defines a new superfamily of defensins.

biochemistry↗

bioRxiv2020

Metabolic cooperation among commensal bacteria supports Drosophila juvenile growth under nutritional stress

The gut microbiota shapes animal growth trajectory in stressful nutritional environments, but the molecular mechanisms behind such physiological benefits remain poorly understood. The gut microbiota is mostly composed of bacteria, which construct metabolic networks among themselves and with the host. Until now, how the metabolic activities of the microbiota contribute to host juvenile growth remains unknown. Here, using Drosophila as a host model, we report that two of its major bacterial partners, Lactobacillus plantarum and Acetobacter pomorum engage in a beneficial metabolic dialogue that boosts host juvenile growth despite nutritional stress. We pinpoint that lactate, produced by L. plantarum, is utilized by A. pomorum as an additional carbon source, and A. pomorum provides essential amino-acids and vitamins to L. plantarum. Such bacterial cross-feeding provisions a set of anabolic metabolites to the host, which may foster host systemic growth despite poor nutrition. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=165 SRC="FIGDIR/small/119370v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@1923739org.highwire.dtl.DTLVardef@679795org.highwire.dtl.DTLVardef@110cbecorg.highwire.dtl.DTLVardef@1bc0804_HPS_FORMAT_FIGEXP M_FIG C_FIG HIGHLIGHTSO_LIL. plantarum feeds lactate to A. pomorum C_LIO_LIA. pomorum supplies essential amino acids and vitamins to L. plantarum C_LIO_LIMicrobiota metabolic dialogue boosts Drosophilas larval growth C_LIO_LILactate utilization by Acetobacter releases anabolic metabolites to larvae C_LI

microbiology↗

bioRxiv2019

Commensal bacteria differentially shape the nutritional requirements of Drosophila during juvenile growth

The interplay between nutrition and the microbial communities colonizing the gastro-intestinal tract (i.e. gut microbiota) determines juvenile growth trajectory. Nutritional deficiencies trigger developmental delays, and an immature gut microbiota is a hallmark of pathologies related to childhood undernutrition. However, how commensal bacteria modulate the impact of nutrition on juvenile growth remains elusive. Here, using gnotobiotic Drosophila melanogaster larvae independently associated with two model commensal bacterial strains, Acetobacter pomorumWJL (ApWJL) and Lactobacillus plantarumNC8 (LpNC8), we performed a large-scale, systematic nutritional screen based on larval growth in 40 different and precisely controlled nutritional environments. We combined these results with genome-based metabolic network reconstruction to define the biosynthetic capacities of Drosophila germ-free (GF) larvae and its two commensal bacteria. We first established that ApWJL and LpNC8 differentially fulfills the nutritional requirements of the ex-GF larvae and parsed such difference down to individual amino acids, vitamins, other micronutrients and trace metals. We found that Drosophila commensal bacteria not only fortify the hosts diet with essential nutrients but, in specific instances, functionally compensate for host auxotrophies, by either providing a metabolic intermediate or nutrient derivative to the host or by uptaking, concentrating and sparing contaminant traces of micronutrients. Our systematic work reveals that, beyond the molecular dialogue engaged between the host and its commensal partners, Drosophila and its facultative bacterial partners establish an integrated nutritional network relying on nutrients sparing and utilization.

physiology↗