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In order to investigate the mechanisms of final maturation and capacitation of spermatozoa in Pecten maximus, we used a 2D proteomic approach coupled with MALDI-TOF/TOF mass spectrometry (MS) and bioinformatics search against the Pecten database, to set up a reference map of the proteome of spawned spermatozoa, and identified 133 proteins on the basis of the EST database. These proteins are mainly involved in energy production, ion and electron transport (44%), cell movement (22%) and developmental processes (10%). Comparison between proteomes of spermatozoa collected before and after transit through the genital ducts of P. maximus led to the identification of differentially expressed proteins. Most of them are associated with energy metabolism (aconitate hydratase, malate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase), indicating important modifications of energy production during transit in gonoducts, potentially linked with acquisition of sperm motility. Three proteins involved in cell movement (Tektin-2, tubulin and microtubule-associated protein RP/EB family member 3) were down-regulated in spermatozoa stripped from the gonad. 40S ribosomal protein SA, involved in maturation of 40S ribosomal subunits, was also found to be down-regulated in spermatozoa obtained by induced spawning, suggesting reduction of the efficiency of RNA translation, a characteristic of late spermatozoon differentiation. These results confirm that maturation processes of P. maximus spermatozoa during transit through the gonoduct involve RNA translation, energy metabolism and structural proteins implicated in cell movement. Spermatozoa maturation processes clearly differ between P. maximus and gonochoric or alternately hermaphroditic bivalves, potentially in relation to reproductive strategies: the final maturation of the spermatozoon along the genital tract probably contributes to reduction of autofertilization in this simultaneously hermaphroditic species. 00000 ăWOS:000386901500011 International audience

The identification and delimitation of species boundaries are essential for understanding speciationand adaptation processes and for the management of biodiversity as well as development forapplications. Ophiocordyceps unilateralis sensu lato is a complex of fungal pathogens parasitizingFormicine ants, inducing zombie behaviors in their hosts. Previous taxonomic works with limitednumbers of samples and markers led to the “one ant-one fungus” paradigm, resulting in the use ofant species as a proxy for fungal identification. Here, a population genomic study with sampling onthree ant species across Thailand supported the existence of host-specific species in O. unilateraliss.l. with no footprints of long term introgression despite occasional host shifts and first-generationhybrids. We further detected genetic clusters within the previously delimited fungal species, witheach little footprints of recombination, suggesting high levels of inbreeding. The clusters withineach of O. camponoti-leonardi and O. camponoti-saundersi were supported by differentiationthroughout the genome, suggesting they may constitute further cryptic species parasitizing the samehost, challenging the one ant-one fungus paradigm. These genetic clusters had differentgeographical ranges, supporting different biogeographic influences between the north/center and thesouth of Thailand, reinforcing the scenario in which Thailand endured compartmentation during thelatest Pleistocene glacial cycles. International audience