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 slidemounting 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 temperature-sensitive 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. OPEN ACCESS Citation: Testa ND, Kaul S, Le KN, Zhan M, Lu H, Paaby AB (2020) A portable, low-cost device for precise control of specimen temperature under stereomicroscopes. PLoS ONE 15(3): e0230241.

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

“…However, the extent of condition-dependent interactions in RNAi may preclude true experimental control. For example, temperature likely plays an unseen hand in RNAi experimentation, 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). We controlled environmental temperature by conducting all RNAi assays at 20°C, but RNAi competence may be maximized at different temperatures in different 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).…”

Diversification of small RNA pathways underlies germline RNA interference incompetence in wild Caenorhabditis 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 strains 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 and Claycomb 2014 ).…”