A portable, low-cost device for precise control of specimen temperature under stereomicroscopes

Abstract

To facilitate precise and convenient control of biological sample temperature, we developed a low-cost device that can be used independently or with any stereomicroscope. The purpose of the device is to control the thermal environment during experimental intervals in which a specimen must be manipulated outside of an incubator, e.g. for dissection or slide-mounting in preparation for imaging. Sample temperatures can be both cooled to below and heated to above room temperatures, and stably maintained at a precision of +/-0.1˚C. To demonstrate the utility of this device, we report improved characterization of the penetrance of a short-acting temperaturesensitive allele in C. elegans embryos, and identification of the upper temperature threshold for embryonic viability for six Caenorhabditis species. By controlling the temperature environment even as a specimen is manipulated, this device offers consistency and flexibility, reduces environmental noise, and enables precision timing in experiments requiring temperature shifts.

Diversification of small RNA pathways underlies germline RNAi incompetence in wild C. elegans strains

“…Identifying mechanisms of variation will help to bridge the gulf between our understanding of the genetics of RNAi and the role of RNAi in nature, and future work may benefit from evaluating wild-type isolates in the context of carefully chosen environmental perturbations ( Rockman, 2008 ). For example, temperature likely matters for RNAi, given the exquisite sensitivity of C. elegans to temperature ( Testa et al, 2020 ) and the intimate relationship between temperature and other stresses and RNAi ( Frézal et al, 2018; Houri-Zeevi et al, 2021; Pagliuso et al, 2021 ); our observations of QX1211 would have been obscured without rigorous temperature control. Sydney Brenner’s selection of C. elegans as a model species, and N2 as the strain of study, was fortuitous for the future discovery of RNAi ( Félix, 2008 ), and it remains the most fertile area for elucidating gene regulation by small RNAs ( Youngman & Claycomb, 2014 ).…”

Open-Source Thermometer, Temperature Controller, and Light Meter for Use in Animal Facilities and During Experiments

“…Device cost starts at $40. This platform can also be used to regulate temperature in a sample chamber using a simple heating element and proportional control scheme, similar to previously reported devices to keep and rapidly change temperature conditions under a stereomicroscope [7] or confocal microscope [8].…”