Pheromonal Cues Deposited by Mated Females Convey Social Information about Egg-Laying Sites in Drosophila Melanogaster.

Individuals can make choices based on information learned from others, a phenomenon called social learning. How observers differentiate between which individual they should or should not learn from is, however, poorly understood. Here, we showed that Drosophila melanogaster females can influence the choice of egg-laying site of other females through pheromonal marking. Mated females mark territories of high quality food by ejecting surplus male sperm containing the aggregation pheromone cis-11-vaccenyl acetate (cVA) and, in addition, deposit several sex- and species-specific cuticular hydrocarbon (CHC) pheromones. These pheromonal cues affect the choices of other females, which respond by preferentially laying eggs on the marked food. This system benefits both senders and responders, as communal egg laying increases offspring survival. Virgin females, however, do not elicit a change in the egg-laying decision of mated females, even when food has been supplemented with ejected sperm from mated females, thus indicating the necessity for additional cues. Genetic ablation of either a female's CHC pheromones or those of their mate results in loss of ability of mated females to attract other females. We conclude that mated females use a pheromonal marking system, comprising cVA acquired from male ejaculate with sex- and species-specific CHCs produced by both mates, to indicate egg-laying sites. This system ensures information reliability because mated, but not virgin, females have both the ability to generate the pheromone blend that attracts other flies to those sites and a direct interest in egg-laying site quality.

No protective effect of breastfeeding on inhibitor formation in severe hemophilia.

It has been suggested that breastfeeding may prevent inhibitor formation in patients with hemophilia. In a single-center retrospective cohort study, the authors studied the association between breastfeeding and inhibitor development in 90 severe hemophilia A patients born 1975-2003. Mean follow-up was 13.2 years (standard deviation 8.7). A total of 62% of patients received breastfeeding and 20% developed inhibitors. The inhibitor rate according to breastfeeding was similar: 21% in patients who were breastfed and 18% in others. Patients who were breastfed received their first treatment 0.3 years earlier. After adjustment for age at first treatment, we found no protective effect of breastfeeding on inhibitor formation.