One of my favorite things about the Worm meetings each summer is taking brand-new students, right after they join the lab. Watching new students immerse themselves in wormy-awesomeness is amazing – and I am always excited to see how enthusiastic the new students are! It is a great way to jump-start graduate studies in the Miller Lab, in my opinion. This year, our newest grad student is Katherine Manbeck, who is joining us from the Neurobiology and Behavior program. Here are her reflections on the International Worm Meeting:
There was significant discussion at the 19th international C. Elegans meeting of worm predators, such as nematophagous fungus and predator nematodes. The Sternberg Lab at Cal Tech studies the carnivorous nematophagous fungi, A. Oligospora (abstract). The fungus produces traps for worms only in the presence of the C. Elegans pheromone ascaroside. A. Oligospora produces significantly reduced traps in the presence of dauers alone, indicating a reduced pheromone release in developmental diapause; if this is the case, one wonders when in development pheromone release begins or what the transition looks like.
Interestingly, a compound produced by A. Oligospora is attractive to C. Elegans in an AWC neuron-dependent way (Hsueh et al). AWC olfactory neurons are critical for chemotaxis to volatile odorants, particularly turn promotion and search behavior. Their role in promoting directed movement toward a volatile compound is somewhat unexpected. Taken together, this indicates that C. Elegans and A. Oligospora are likely in an evolutionary arms race.
Similarly, C. Elegans and predator nematodes experience co-evolution, as explored by Kevin Curran in the lab of Sreekanth Chalasani (abstract). The development of teeth in the Pristionchus Pacificus is a particularly interesting phenomenon; the omnivore can either be eurystomatous or stenostomatous. The former, in which the P. Pacificus have two teeth which “scissor” together, is much more effective than the single tooth which characterizes stenostomum. Surprisingly, both phenotypes arise from a single identical genome, in a phenomenon attributed to developmental conditions (for more information on this phenomenon and the additionally fascinating low occurrence of eurystomatous in male nematodes, see the research of Erik Ragsdale (abstract)).
To feed on C. Elegans, P. Pacificus bite and trap worms (primarily L1s) and use their teeth to break the cuticular exoskeleton and consume the worm. C. Elegans ASI, ASJ, and ASH chemosensory neurons modulate a defensive aversive response to P. Pacificus. Further, exposure to fluoxetine, an SSRI (selective serotonin reuptake inhibitor) decreases C. Elegans avoidance response, which the presenters took to indicate that predator avoidance may mimic fear or anxiety-like human responses. This claim seems a bit farfetched, but the overall message was interesting and well researched.
This summary of predation of C. Elegans represents but a small subsection of information presented at the 2013 Worm Meeting. Other highlights included the problematic but unique work implying that the timing of death by thermal stress follows the trajectory of normal aging by Nicholas Stroustrup of the Fontana Lab (abstract), a preliminary but titillating poster exploring the inhibitors of transcription factor-driven cell reprogramming given by Ena Kolundzic (Tursun lab (abstract)), and a talk about the male C. Elegans refractory period (see work by the Garcia Lab (abstract)).
One of the most promising tools discussed at the conference was a project focused on mapping the connectome: wormwiring, discussed by Cook from the Emmons Lab (abstract). This tool, which is still being developed, provides connectivity data based on electromicroscopic images of C. Elegans males, hermaphrodites, and larva. This could be a useful way of microscopically evaluating which neurons may be likely to be involved in the protective effect of HIF-1 in H2S.