Male Accessory Gland Protein Reduces Egg Laying in a Simultaneous Hermaphrodite

Seminal fluid is an important part of the ejaculate of internally fertilizing animals. This fluid contains substances that nourish and activate sperm for successful fertilization. Additionally, it contains components that influence female physiology to further enhance fertilization success of the sperm donor, possibly beyond the recipient's optimum. Although evidence for such substances abounds, few studies have unraveled their identities, and focus has been exclusively on separate-sex species. We present the first detailed study into the seminal fluid composition of a hermaphrodite (Lymnaea stagnalis). Eight novel peptides and proteins were identified from the seminal-fluid-producing prostate gland and tested for effects on oviposition, hatching and consumption. The gene for the protein found to suppress egg mass production, Ovipostatin, was sequenced, thereby providing the first fully-characterized seminal fluid substance in a simultaneous hermaphrodite. Thus, seminal fluid peptides and proteins have evolved and can play a crucial role in sexual selection even when the sexes are combined

Phenotypic and transcriptional responses associated with multi-generation exposure of Folsomia candida to engineered nanomaterials

Sublethal effects of toxicants may cumulate over time and become apparent only when test organisms are exposed for multiple generations. In this study we determined phenotypic effects and transcriptional responses in the parthenogenetic soil invertebrate Folsomia candida over four generations, followed by two generations of recovery. Animals were exposed to two metal-based nanomaterials (NMs): copper oxide (CuO) and tungsten carbide–cobalt (WCCo), both homogenously mixed in with the soil. Survival and reproduction were not affected in any of four consecutive generations of F. candida exposed to CuO-NM at concentrations as high as 6400 mg Cu per kg dry LUFA 2.2 soil. WCCo-NM affected reproduction and survival from the third generation onwards, with EC50 values between 2400 and 5600 mg NM per kg dry soil, but recovery was seen in recovery generations 1 and 2 when kept in clean soil. Histological investigations showed that WCCo-NM (3200 mg kg−1) induced tissue damage and loss of villi from the gut epithelial cells. Expression of four target genes known to be responsive to stress were investigated by quantitative PCR at different exposure levels and in different generations. Expression of all genes was significantly affected by NMs even though exposures were below toxic threshold concentrations. In addition, gene expression did not always return to control levels during consecutive recovery over two generations in clean soil. This shows that gene expression assays can detect physiological alterations cumulating from one generation to the next initially without visible effects on phenotypic variables such as reproduction. The possibility of multi-generation carry-over of sublethal toxicity needs more attention in environmental risk assessment

The fate of received sperm in the reproductive tract of a hermaphroditic snail and its implications for fertilisation.

Multiple mating, sperm storage and internal fertilisation enhance sperm competition. The great pond snail can use stored sperm for over three months, and frequently mates with different partners. This hermaphrodite, Lymnaea stagnalis, can also self-fertilise and often produces egg masses containing both selfed and outcrossed eggs. Hence, a sperm recipient may exert considerable control over paternity. Using microsatellite markers, we show that when allosperm are present, all genotyped eggs are cross-fertilised. We also find that sperm have the opportunity to compete, because double matings lead on average to equal paternity for each sperm donor. This indicates that received sperm are randomly mixed in storage. To gain further insight into the mechanisms underlying the process of sperm storage, digestion and utilisation, we investigated the fate of donated sperm at different times after copulation. We find that within 3 h after transfer most sperm have been transported into the sperm-digesting organ. Fluorescent labelling of sperm in histological sections further reveals that allosperm are not stored in the fertilisation pouch, but upstream in either the hermaphroditic duct, seminal vesicles, or ovotestis. Besides contributing to the understanding of the mechanisms underlying sperm competition and/or cryptic sperm choice, this study shows that mixed mating cannot be treated as a separate issue in hermaphroditic animals. © Springer Science+Business Media B.V. 2008

Importância do positivismo em tempos pós-modernos: a racionalidade jurídica do positivismo ao pós-positivismo

a b s t r a c t Competition for fertilisation in hermaphroditic animals seems to have led to many odd behaviours and complex morphologies involved in the transfer of accessory-gland products to the partner. Terrestrial slugs of the genus Deroceras show remarkably elaborate and interspecifically diverse penis morphologies and mating behaviours. Most species have an appending penial gland, which in Deroceras panormitanum consists of a few long fingers that are everted after sperm exchange and laid onto the partner's back. To investigate whether this gland transfers a secretion onto the partner's skin, we killed slugs at different mating stages and studied their penial glands and skin histologically. Two types of secretion granules appeared at a very early stage of courtship, and the penial gland was already filled 15 min into the courtship. At copulation, the gland everted this secretion onto the partner's body, where it remained for at least 50 min. No lysis of skin tissue or other effects on the skin were observed. The slugs tried to lick the received secretion off their own body, and some droplets were observed to be shed with the body mucus. Our results indicate the external application of a glandular substance that could function as either a pheromone or allohormone. The behaviours of the recipients suggest sexual conflict, although mutual interest cannot be ruled out

Histological sections of the dart gland and sac.

<p><b>A.</b> The section of the dart gland shows the muscular dart-gland ducts (DGD) surrounded by dart-gland tissue (DG, dart-glands). <b>B.</b> The section of the dart sac (DS) shows its thick muscular layer. Inside the sac, many of the dart-gland channels (DGC) leading into the channels of the dart can be clearly seen. These sections are taken from the same individual, but note that the dart in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0069968#pone-0069968-g001" target="_blank">Figure 1</a> is from a different individual.</p

Scanning electron micrograph of the love dart of <i>Everettia corrugata corrugata</i>.

<p><b>A.</b> The side view illustrates the row of perforations on one of the two sides. <b>B.</b> The cross section shows the channels inside the shaft of the dart that connect to the perforations along the dart’s flank.</p

Effects of age, size, and mating history on sex role decision of a simultaneous hermaphrodite

Nakadera Y, Swart EM, Maas JPA, Montagne-Wajer K, Ter Maat A, Koene JM. Effects of age, size, and mating history on sex role decision of a simultaneous hermaphrodite. Behavioral Ecology. 2014;26(1):232-241.Contrasting with separate-sexed animals, simultaneous hermaphrodites display unique reproductive strategies as they are male and female at the same time. Simultaneous hermaphrodites that copulate unilaterally, for instance, make a decision to mate as a male or female. Previous studies have demonstrated that sex role preference in hermaphrodites is flexible and is controlled by several, often confounding, factors. We examined the relationship between sex role decisions and 3 life-history traits (age, size, and mating history) in the great pond snail, Lymnaea stagnalis . Based on our field observations, which indicate that adult individuals show overlapping generations and large variation in body size during the breeding season, we performed a sex role choice experiment in the laboratory. We found that young and small snails mate as males first. Both age and size significantly affected sex role decision, with age having a stronger effect. Furthermore, we tested whether L. stagnalis becomes reluctant to inseminate a mate after being inseminated because it is known that after insemination, male investment substantially reduces. Contrary to expectations, our results indicate that the receipt of seminal fluid does not seem to reduce male motivation. In sum, sex role decisions in L. stagnalis are largely determined by age and size but not by having received seminal fluid. This mating pattern, however, does not fully support the size-advantage model because large or old individuals did not perform better as females in our experiment. These results imply a conflicting mating interest, rather than harmonious agreement, between age- and size-different hermaphrodites