Accessory gland proteins of males in the male‐diphenic ant Cardiocondyla obscurior

Abstract

Seminal fluid proteins are important agents in sperm competition and sexual conflict. In solitary insects, males and females may have different interests concerning the outcome of a mating episode, and males may use seminal fluid to manipulate the physiology and behaviour of the female against the latter's fitness interests. Less is known about the role of seminal fluids in social insects, where the interests of mating partners are more aligned because of life‐long pair‐bonding. In the male‐diphenic ant Cardiocondyla obscurior, mating even with sterilized males appears to prolong the lifespan of queens, suggesting a positive role of seminal fluids. In the present study, using two approaches (two‐dimensional gel electrophoresis/mass spectrometry and representational difference analysis), we analyze the seminal fluid and the male accessory glands of both winged and wingless males of C. obscurior. The results obtained reveal the presence of hundreds of proteins, of which proteases and protease inhibitors are also widespread in the seminal fluids of other insects.

Seminal fluid and accessory male investment in sperm competition

“…(Associated sperm trait plasticity is based on the same study unless additional sources are cited.) plainfin midshipman fish, Porichthys notatus guarder versus sneaker alternative reproductive tactics accessory glands-lobules and total accessory gland mass (but not nodes) relatively larger in guarders [83] yes-evidence for trade-off: sneaker males have relatively larger testes and much larger ejaculates, but guarders have higher sperm velocity owing to lobule secretions black goby, Gobius niger guarder versus sneaker alternative reproductive tactics accessory glands-seminal vesicles and mesorchial glands larger in guarder males [84] yes-evidence for trade-off: sneaker males have larger testes; seminal fluid enhances the velocity and fertilization ability of guarder sperm [85] grass goby, Zosterisessor ophiocephalus large (guarder) versus small (sneaker) males seminal vesicles-larger in larger (guarder) males [86] yes-evidence for trade-off, because testes larger in smaller (sneaker) males Chinook salmon, Oncorhynchus tswatchysha jack versus hooknose alternative reproductive tactics seminal fluid proteome [87] yes-jacks (sneakers) have relatively larger testes and faster sperm [88]; seminal fluid can affect own and rival sperm velocity [89] ant, Cardiocondyla obscurior winged versus wingless males seminal fluid proteome-56 out of 920 spots differed in intensity [90] yes [91]. with more rivals (but see [92]) [93] yes-daily sperm production rate and epididymal sperm numbers increase with more rivals [92] bank vole, Myodes glareolus number of rival male odours seminal vesicle size [94] no-testis size, epididymal sperm counts, daily sperm production and sperm motility all unaffected fruit fly, Drosophila melanogaster sperm competition intensity cues seminal fluid gene expression (2 out of 3 genes investigated) [95] n/a population density during larval development sex peptide and ovulin expression [96] n/a larval density, presence/absence of adult males during larval development accessory gland size-larger in response to competitive cues [97] no-testis size unaffected or reduced by same cues socio-sexual environment seminal fluid gene expression 2, 26 and 50 h after exposure to rivals (complex responses across genes and replicates) [98] n/a (Continued.…”

“…[125,126]). (a) bank vole, Myodes glareolus dominant versus subordinate males seminal vesicle size (but not copulatory plug size)-larger in dominant males [81] yes-absolute (but not relative) testis size larger and sperm numbers per ejaculate greater in dominant males house mouse, Mus musculus domesticus dominant versus subordinate males seminal vesicle size (larger in dominant males), protein concentration (higher in subordinates) and seminal fluid protein abundance (consistent differences in multiple proteins according to social status) [82] yes-dominant males have greater epididymal sperm reserves (despite similar testis size to subordinates) plainfin midshipman fish, Porichthys notatus guarder versus sneaker alternative reproductive tactics accessory glands-lobules and total accessory gland mass (but not nodes) relatively larger in guarders [83] yes-evidence for trade-off: sneaker males have relatively larger testes and much larger ejaculates, but guarders have higher sperm velocity owing to lobule secretions black goby, Gobius niger guarder versus sneaker alternative reproductive tactics accessory glands-seminal vesicles and mesorchial glands larger in guarder males [84] yes-evidence for trade-off: sneaker males have larger testes; seminal fluid enhances the velocity and fertilization ability of guarder sperm [85] grass goby, Zosterisessor ophiocephalus large (guarder) versus small (sneaker) males seminal vesicles-larger in larger (guarder) males [86] yes-evidence for trade-off, because testes larger in smaller (sneaker) males Chinook salmon, Oncorhynchus tswatchysha jack versus hooknose alternative reproductive tactics seminal fluid proteome [87] yes-jacks (sneakers) have relatively larger testes and faster sperm [88]; seminal fluid can affect own and rival sperm velocity [89] ant, Cardiocondyla obscurior winged versus wingless males seminal fluid proteome-56 out of 920 spots differed in intensity [90] yes [91].…”

Genome-wide identification and expression analysis of the mating-responsive genes in the male accessory glands of Spodoptera litura (Lepidoptera: Noctuidae)

“…The secretions from MAGs transferred along with sperms to the female reproductive tract during mating facilitate several processes that modify female post-mating behaviour. Across diverse taxa, transcriptome and proteome analysis [ 5 , 8 , 20 , 44 , 51 , 55 ] suggests that MAG proteins are transferred during mating affecting the reproductive success of both sexes and providing valuable information for a comprehensive understanding of insect reproduction. Thus, transcriptome analysis is one of the possible ways to identify the mating-responsive genes in the MAGs of S. litura .…”

Discovering novel reproductive genes in a non-model fly using de novo GridION transcriptomics

“…Many studies on AG secretions have focused on model systems with well-characterized reference genomes like Drosophila melanogaster, disease vectors like Aedes mosquitoes, as well as agricultural pests like Tribolium castaneum and Callosobruchus maculatus beetles ( Parthasarathy et al, 2009 ; Avila et al, 2011 ; Goenaga et al, 2015 ; Yamane et al, 2015 ; Ahmed-Braimah, 2016 ; Sayadi et al, 2016 ; Bayram et al, 2017 ; Bayram et al, 2019 ; Degner et al, 2019 ; Wigby et al, 2020 ). A handful of other insect groups that include crickets, moths, bees, and ants have also been explored ( Braswell et al, 2006 ; Gorshkov et al, 2015 ; Fuessl et al, 2018 ; Gotoh et al, 2018 ; Saraswathi et al, 2020 ), but overall, studies on non-model insect reproductive gene discovery are still sparse. In a recent study on dung beetle, we discovered that AGs are hotspots for recruitment of completely novel genes for reproductive function whilst the testes generally express more conserved genes involved in sperm production ( Mrinalini et al, 2021 ).…”