ABSTRACT
The insulin/insulin-like signaling (IIS) pathway regulates many of C. elegans' adult functions, including learning and memory 1 . While whole-worm and tissue-specific transcriptomic analyses have identified IIS targets 2,3 , a higher-resolution single-cell approach is required to identify changes that confer neuron-specific improvements in the long-lived insulin receptor mutant, daf-2 . To understand how behaviors that are controlled by a small number of neurons change in daf-2 mutants, we used the deep resolution of single-nucleus RNA sequencing to define each neuron type's transcriptome in adult wild-type and daf-2 mutants. First, we found surprising differences between wild-type L4 larval neurons and young adult neurons in chemoreceptor expression, synaptic genes, and learning and memory genes. These Day 1 adult neuron transcriptomes allowed us to identify adult AWC-specific regulators of chemosensory function and to predict neuron-to-neuron peptide/receptor pairs. We then identified gene expression changes that correlate with daf-2's improved cognitive functions, particularly in the AWC sensory neuron that controls learning and associative memory 4 , and used behavioral assays to test their roles in cognitive function. Combining deep single-neuron transcriptomics, genetic manipulation, and behavioral analyses enabled us to identify genes that may function in a single adult neuron to control behavior, including conserved genes that function in learning and memory. One-Sentence Summary: Single-nucleus sequencing of adult wild-type and daf-2 C. elegans neurons reveals functionally relevant transcriptional changes, including regulators of chemosensation, learning, and memory.
ABSTRACT
Caenorhabditis elegans (C. elegans) lifespan assays constitute a broadly used approach for investigating the fundamental biology of longevity. Traditional C. elegans lifespan assays require labor-intensive microscopic monitoring of individual animals to evaluate life/death over a period of weeks, making large-scale high throughput studies impractical. The lifespan machine developed by Stroustrup et al. (2013) adapted flatbed scanner technologies to contribute a major technical advance in the efficiency of C. elegans survival assays. Introducing a platform in which large portions of a lifespan assay are automated enabled longevity studies of a scope not possible with previous exclusively manual assays and facilitated novel discovery. Still, as initially described, constructing and operating scanner-based lifespan machines requires considerable effort and expertise. Here we report on design modifications that simplify construction, decrease cost, eliminate certain mechanical failures, and decrease assay workload requirements. The modifications we document should make the lifespan machine more accessible to interested laboratories.
