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The choice of criteria to delimit a group or class is a subjective matter, even though the reasoning, the objectives and the criteria themselves should always be clearly stated. This paper is part of a discussion about the criteria used to identify seminal fluid proteins (SFPs) in Drosophila species. SFPs are proteins that are transferred to females during copulation together with sperm. The only way to ascertain that a protein is an SFP is to prove that it is produced in a male reproductive organ and is found in the female reproductive tract after insemination. Nevertheless, the required methodology is labour‐intensive and expensive, and therefore this kind of data is unlikely to be available for many species, precluding comparative and evolutionary studies on the subject. To conduct evolutionary analyses, in a previous study, we capitalized on the accumulated knowledge we have in the model species D. melanogaster to recommend a set of criteria for identifying candidate SFPs in other Drosophila species. Those criteria, based on transcriptomic evidence and in silico predictions from sequences, would allow a good balance between sensitivity (the inclusion of true SFPs) and specificity (the exclusion of false positives). In view of the criticism raised by another group, here we defend our criteria on one hand while accepting there is room for improvement on the other. The results are updated sets of criteria and SFPs that we believe can be useful in future evolutionary studies. [ABSTRACT FROM AUTHOR]

(2008) Proteomics reveals novel Drosophila seminal fluid proteins transferred at mating. (1999) Drosophila seminal fluid proteins enter the circulatory system of the mated female fly by crossing the posterior vaginal wall. Keywords: Drosophila; proteomics; reproduction; seminal fluid; Sfp EN Drosophila proteomics reproduction seminal fluid Sfp 533 536 4 09/07/22 20221001 NES 221001 Seminal fluid proteins (Sfps) have striking effects on the behaviour and physiology of females in many insects. [Extracted from the article]

While the striking effects of seminal fluid proteins (SFPs) on females are fairly conserved among Diptera, most SFPs lack detectable homologues among the SFP repertoires of phylogenetically distant species. How such a rapidly changing proteome conserves functions across taxa is a fascinating question. However, this and other pivotal aspects of SFPs' evolution remain elusive because discoveries on these proteins have been mainly restricted to the model Drosophila melanogaster. Here, we provide an overview of the current knowledge on the inter‐specific divergence of the SFP repertoire in Drosophila and compile the increasing amount of relevant genomic information from multiple species. Capitalizing on the accumulated knowledge in D. melanogaster, we present novel sets of high‐confidence SFP candidates and transcription factors presumptively involved in regulating the expression of SFPs. We also address open questions by performing comparative genomic analyses that failed to support the existence of many conserved SFPs shared by most dipterans and indicated that gene co‐option is the most frequent mechanism accounting for the origin of Drosophila SFP‐coding genes. We hope our update establishes a starting point to integrate further data and thus widen the understanding of the intricate evolution of these proteins. [ABSTRACT FROM AUTHOR]

The seed beetle Callosobruchus maculatus is a significant agricultural pest and increasingly studied model of sexual conflict. Males possess genital spines that increase the transfer of seminal fluid proteins (SFPs) into the female body. As SFPs alter female behaviour and physiology, they are likely to modulate reproduction and sexual conflict in this species. Here, we identified SFPs using proteomics combined with a de novo transcriptome. A prior 2D-sodium dodecyl sulphate polyacrylamide gel electrophoresis analysis identified male accessory gland protein spots that were probably transferred to the female at mating. Proteomic analysis of these spots identified 98 proteins, a majority of which were also present within ejaculates collected from females. Standard annotation workflows revealed common functional groups for SFPs, including proteases and metabolic proteins. Transcriptomic analysis found 84 transcripts differentially expressed between the sexes. Notably, genes encoding 15 proteins were highly expressed in male abdomens and only negligibly expressed within females. Most of these sequences corresponded to 'unknown' proteins (nine of 15) and may represent rapidly evolving SFPs novel to seed beetles. Our combined analyses highlight 44 proteins for which there is strong evidence that they are SFPs. These results can inform further investigation, to better understand the molecular mechanisms of sexual conflict in seed beetles. [ABSTRACT FROM AUTHOR]

Mating causes dramatic changes in female insects at the behavioural, physiological and molecular level. The factors driving these changes (e.g. seminal proteins, seminal volume) and the molecular pathways by which these factors are operating have been characterized only in a handful of insect species. In the present study, we use instrumental insemination of honey bee queens to examine the role of the insemination substance and volume in triggering post-mating changes. We also examine differences in gene expression patterns in the fat bodies of queens with highly activated ovaries to determine if events during copulation can cause long-term changes in gene expression. We found that the instrumental insemination procedure alone caused cessation of mating flights and triggered ovary activation, with high-volume inseminated queens having the greatest ovary activation. Hierarchical clustering grouped queens primarily by insemination substance and then insemination volume, suggesting that while volume may trigger short-term physiological changes (i.e. ovary activation) substance plays a greater role in regulating long-term transcriptional changes. The results of gene ontology analysis and comparison with previous studies suggest that both insemination substance and volume trigger molecular post-mating changes by altering overlapping gene pathways involved in honey bee reproduction. We also discuss the effects on two genes ( vitellogenin and transferrin) involved in reproduction and defence responses. [ABSTRACT FROM AUTHOR]

Reproductive proteins are amongst the most evolutionarily divergent proteins known, and research on genetically well-characterized species suggests that postcopulatory sexual selection might be important in their evolution; however, we lack the taxonomic breadth of information on reproductive proteins that is required to determine the general importance of sexual selection for their evolution. We used transcriptome sequencing and proteomics to characterize the sperm and seminal fluid proteins of a cricket, Teleogryllus oceanicus, that has been widely used in the study of postcopulatory sexual selection. We identified 57 proteins from the sperm of these crickets. Many of these had predicted function in glycolysis and metabolism, or were structural, and had sequence similarity to sperm proteins found across taxa ranging from flies to humans. We identified 21 seminal fluid proteins, some of which resemble those found to be involved in postmating changes to female reproduction in other species. Some 27% of sperm proteins and 48% of seminal fluid proteins were of unknown function. The characterization of seminal fluid proteins in this species will allow us to explore their adaptive significance, and to contribute comparative data that will facilitate a general appreciation of the evolution of reproductive proteins within and among animal taxa. [ABSTRACT FROM AUTHOR]