Phéromone | EPFL Graph Search

Une phéromone (ou phérormone ou encore phérohormone) est une substance chimique comparable aux hormones, émise par la plupart des animaux et certains végétaux, et qui agit comme un message entre les individus d'une même espèce (communication intraspécifique, à l'opposé des ectomones impliquées dans la ). Ce composé sémiochimique transmet aux autres organismes des informations qui influencent la physiologie et les comportements (sexuel, maternel, agression, agrégation, pistage…). Très actives, certaines phéromones agissent même en faible quantité, et elles peuvent être transportées et être détectées à plusieurs kilomètres. Chez les mammifères et les reptiles, les phéromones sont principalement détectées par l'organe voméronasal, tandis que les insectes utilisent généralement leurs antennes. À la différence des hormones classiques (insuline, adrénaline, etc.) produites par les glandes endocrines et qui circulent uniquement à l'intérieur de l'organisme en participant à son métabolisme,

Drosophila melanogaster cloak their eggs with pheromones, which prevents cannibalism

Laure Menin, Konstantin Nagornov, Yury Tsybin

Oviparous animals across many taxa have evolved diverse strategies that deter egg predation, providing valuable tests of how natural selection mitigates direct fitness loss. Communal egg laying in nonsocial species minimizes egg predation. However, in cannibalistic species, this very behavior facilitates egg predation by conspecifics (cannibalism). Similarly, toxins and aposematic signaling that deter egg predators are often inefficient against resistant conspecifics. Egg cannibalism can be adaptive, wherein cannibals may benefit through reduced competition and added nutrition, but since it reduces Darwinian fitness, the evolution of anticannibalistic strategies is rife. However, such strategies are likely to be nontoxic because deploying toxins against related individuals would reduce inclusive fitness. Here, we report how D. melanogaster use specific hydrocarbons to chemically mask their eggs from cannibal larvae. Using an integrative approach combining behavioral, sensory, and mass spectrometry methods, we demonstrate that maternally provisioned pheromone 7,11-heptacosadiene (7,11-HD) in the eggshell's wax layer deters egg cannibalism. Furthermore, we show that 7,11-HD is nontoxic, can mask underlying substrates (for example, yeast) when coated upon them, and its detection requires pickpocket 23 (ppk23) gene function. Finally, using light and electron microscopy, we demonstrate how maternal pheromones leak-proof the egg, consequently concealing it from conspecific larvae. Our data suggest that semiochemicals possibly subserve in deceptive functions across taxa, especially when predators rely on chemical cues to forage, and stimulate further research on deceptive strategies mediated through nonvisual sensory modules. This study thus highlights how integrative approaches can illuminate our understanding on the adaptive significance of deceptive defenses and the mechanisms through which they operate.

PUBLIC LIBRARY SCIENCE2019

Quorum Sensing Contributes to Natural Transformation of Vibrio cholerae in a Species-Specific Manner

Melanie Blokesch, Patrick Martin Seitz, Gaia Francesca Marianne Suckow

Although it is a human pathogen, Vibrio cholerae is a regular member of aquatic habitats, such as coastal regions and estuaries. Within these environments, V. cholerae often takes advantage of the abundance of zooplankton and their chitinous molts as a nutritious surface on which the bacteria can form biofilms. Chitin also induces the developmental program of natural competence for transformation in several species of the genus Vibrio. In this study, we show that V. cholerae does not distinguish between species-specific and non-species-specific DNA at the level of DNA uptake. This is in contrast to what has been shown for other Gram-negative bacteria, such as Neisseria gonorrhoeae and Haemophilus influenzae. However, species specificity with respect to natural transformation still occurs in V. cholerae. This is based on a positive correlation between quorum sensing and natural transformation. Using mutant-strain analysis, cross-feeding experiments, and synthetic cholera autoinducer-1 (CAI-1), we provide strong evidence that the species-specific signaling molecule CAI-1 plays a major role in natural competence for transformation. We suggest that CAI-1 can be considered a competence pheromone.

American Society for Microbiology2011

The oxylipin chemistry of attraction and defense in brown algae and diatoms

Max Planck Institute for Chemical Ecology, Jena, Germany. This review covers the research on brown algal pheromones from the first structural characterisation of an active principle in 1971 to the recent detailed insight into their biosynthesis. Development of analytical methods and bioassays that lead to the identification of a structural variety of different fatty acid-derived pheromones are reported. Special emphasis is focused on the inactivation of initially released pheromones through pericyclic reactions. The impact of pheromone-research on the defensive chemistry of brown algae and diatoms is discussed. 121 references are cited.

2002

Drosophila melanogaster cloak their eggs with pheromones, which prevents cannibalism

Laure Menin, Konstantin Nagornov, Yury Tsybin

PUBLIC LIBRARY SCIENCE2019