[
International Worm Meeting,
2019]
For animals that do not provide parental care, when and where eggs are laid in the environment can have profound effects on the reproductive success of an individual. Because of its importance, it is not surprising that egg-laying is highly regulated in response to environmental cues. This regulation, coupled with the well described neural circuitry involved in the act of egg-laying, make it a great system for studying how animals interpret their environment and make behavioral choices. To facilitate this line of research we have developed a microfluidic "egg-counter" that allows 32 nematodes to reside in individual growth chambers while their egg-laying behavior is recorded at a sub-minute temporal resolution. The platform utilizes a perfusion-based feeding system that allows experimental control of the chemical environment as well as a built-in temperature control unit that allows the temperature to be patterned with 0.1 deg C accuracy without the use of incubators or temperature control rooms. Preliminary analysis of egg-laying behavior from wildtype animals in our microfluidic environment grossly fits that of the three-state model used to describe egg-laying on agar plates, with the log-tail distribution of egg-laying intervals exhibiting a bi-phasic distribution consistent with two interval types, inter and intra-cluster intervals. We will present a genetic characterization of the role of insulin signaling in regulating egg-laying behavior.
[
Front Microbiol,
2019]
Antimicrobial drug discovery against drug-resistant bacteria is an urgent need. Beyond agents with direct antibacterial activity, anti-virulent molecules may also be viable compounds to defend against bacterial pathogenesis. Using a high throughput screen (HTS) that utilized <i>Caenorhabditis elegans</i> infected with methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) strain of MW2, we identified 4-(1,3-dimethyl-2,3-dihydro-1H-benzimidazol-2-yl)phenol (BIP). Interestingly, BIP had no <i>in vitro</i> inhibition activity against MW2, at least up to 64 g/ml. The lack of direct antimicrobial activity suggests that BIP could inhibit bacterial virulence factors. To explore the possible anti-virulence effect of the identified molecule, we first performed real-time PCR to examine changes in virulence expression. BIP was highly active against MRSA virulence factors at sub-lethal concentrations and down-regulated virulence regulator genes, such as <i>agrA</i> and <i>codY</i>. However, the benzimidazole derivatives omeprazole and pantoprazole did not down-regulate virulence genes significantly, compared to BIP. Moreover, the BIP-pretreated MW2 cells were more vulnerable to macrophage-mediated killing, as confirmed by intracellular killing and live/dead staining assays, and less efficient in establishing a lethal infection in the invertebrate host <i>Galleria mellonella</i> (<i>p</i> = 0.0131). We tested the cytotoxicity of BIP against human red blood cells (RBCs), and it did not cause hemolysis at the highest concentration tested (64 g/ml). Taken together, our findings outline the potential anti-virulence activity of BIP that was identified through a <i>C. elegans</i>-based, whole animal based, screen.