Abstract
The dauer larva is a specialized dispersal stage in the nematode Caenorhabditis elegans that allows the animal to survive starvation for an extended period of time. The dauer does not feed, but uses chemosensation to identify new food sources and to determine whether to resume reproductive growth. Bacteria produce food signals that promote recovery of the dauer larva, but the chemical identities of these signals remain poorly defined. We find that bacterial fatty acids in the environment augment recovery from the dauer stage under permissive conditions. The effect of increased fatty acids on different dauer constitutive mutants indicates a role for insulin peptide secretion in coordinating recovery from the dauer stage in response to fatty acids. These data suggest that worms can sense the presence of fatty acids in the environment and that elevated levels can promote recovery from dauer arrest. This may be important in the natural environment where the dauer larva needs to determine whether the environment is appropriate to support reproductive growth following dauer exit.
Highlights
During development, the nematode C. elegans acutely senses its environment by integrating signals pertaining to food availability, temperature, and population density in order to determine whether conditions are appropriate to support normal larval development and subsequent progeny production [1]
Bacterial Fatty Acids Influence Dauer Recovery We found that cfa bacteria did not affect the fraction of daf
We considered that the presence of cyclopropane fatty acids (CFA) in the worm could be slowing down dauer recovery, so we grew dauers on K12 and cfa bacteria and shifted them to the opposite condition during recovery
Summary
The nematode C. elegans acutely senses its environment by integrating signals pertaining to food availability, temperature, and population density in order to determine whether conditions are appropriate to support normal larval development and subsequent progeny production [1]. If conditions are deemed unsuitable, developing first-stage larvae are able to change their developmental program to enter an alternate third larval stage called the dauer larva, which is non-feeding, non-reproducing, and long-lived [2,3]. The dauer pheromone, temperature, and food availability are the major signals that regulate dauer entry and exit [1]. In early studies of dauer formation, Riddle and colleagues determined that entry into dauer is influenced by a pheromone which is produced by the worm and whose concentration reflects population density [4,5,6]. Little is known about the chemical nature of the bacterial food signal [7]
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