Specialized structure and function of the apical extracellular matrix at sense organs

Transcriptomic response of male Anastrepha fraterculus (Diptera: Tephritidae) to sexual stimulation by host plant volatiles

Anastrepha fraterculus is a major pest of fruits in South America. Previous studies revealed that males exposed to volatiles from guava, a likely ancestral host, intensify courtship behavior and increase mating success. However, the molecular and physiological mechanisms underlying this effect remain unknown. Here, we explore the impact of exposure to guava essential oil volatiles on the gene expression profile of adult male heads through de novo transcriptome assembly and differential expression analysis. We found 678 differentially expressed genes (FDR < 0.05 and |FC| > 2), 308 of which were over-expressed in exposed males and 370 in non-exposed males. The exposure treatment affected the transcription of genes putatively involved in mucus-forming, lipid metabolism and neuropeptide processing. Our findings provide the first insights into the molecular mechanisms underlying sexual stimulation in A. fraterculus males triggered by host fruit volatiles.

C. elegans epicuticlins define specific compartments in the apical extracellular matrix and function in wound repair

The apical extracellular matrix (aECM) of external epithelia often contains lipid-rich outer layers that contribute to permeability barrier function. The external aECM of nematodes is known as the cuticle and contains an external lipid-rich layer - the epicuticle. Epicuticlins are a family of tandem repeat cuticle proteins of unknown function. Here, we analyze the localization and function of the three C. elegans epicuticlins (EPIC proteins). EPIC-1 and EPIC-2 localize to the surface of the cuticle near the outer lipid layer, as well as to interfacial cuticles and adult-specific struts. EPIC-3 is expressed in dauer larvae and localizes to interfacial aECM in the buccal cavity. Skin wounding in the adult induces epic-3 expression, and EPIC proteins localize to wound sites. Null mutants lacking EPIC proteins are viable with reduced permeability barrier function and normal epicuticle lipid mobility. Loss of function in EPIC genes modifies the skin blistering phenotypes of Bli mutants and reduces survival after skin wounding. Our results suggest EPIC proteins define specific cortical compartments of the aECM and promote wound repair.