Critical thermal minimum assay (Drosophilidae)

Knowledge graph centered on Critical thermal minimum assay (Drosophilidae) with 23 nodes and 63 connections. Top connected: Spruce, Bacteria, thermal performance, Drosophila melanogaster, ecological speciation.

Method synopsis

Laboratory assays measuring critical thermal minimum (CTmin) and chill coma recovery time (CCRT) to quantify cold tolerance in Drosophila populations.

Synthesized from method descriptions across 1 paper using this protocol.

Procedure from a recent peer-reviewed implementation

Steps below were extracted from the most recent peer-reviewed implementation of this protocol in the corpus — Cold adaptation drives population genomic divergence in the ecological specialist, <i> Drosophila montana </i> (2021), Molecular Ecology. Implementations in other papers (listed below) may differ.

1. Cold tolerance phenotyping - CTmin assay
   Fly samples collected from five populations (Seward, Terrace, Ashford, Crested Butte, and Korpilahti) from mass-bred populations maintained in laboratory since 2013-2014. CTmin tests based on detecting temperature at which flies lose neuromuscular function and enter reversible state of chill coma. Flies placed into tubes sealed with parafilm and submerged into 30% glycol-water mixture in Julabo F32-HL chamber. Temperature decreased at rate of 0.6°C per min from 19°C to -6°C and CTmin determined by eye as temperature at which fly was unable to stand on its legs.
   Quantities: 328 females and 302 males total, between 22 and 30 flies per batch, 21 batches total, 32-46 flies per population per sex testedDuration: Temperature ramped from 19°C to -6°C at 0.6°C per minuteConditions: Constant temperature (19 ± 1°C) and light (24 h of light) maintenance, 20-21 days old flies at testing
   Equipment: parafilm tubes, 30% glycol-water mixture, Julabo F32-HL chamber
2. Cold tolerance phenotyping - CCRT assay
   Same individual flies first assayed for CTmin then used for CCRT. After CTmin test, temperature set to -6°C and flies left in this temperature for 16 h, were then quickly taken out of glycol-water bath and flies' CCRT determined as time required for flies to recover from chill coma and stand on their legs. Ambient room temperatures recorded during trials.
   Quantities: Same 328 females and 302 males from CTmin assayDuration: 16 hours at -6°C, then recovery time measuredConditions: Ambient room temperatures recorded, no statistically significant effect of room temperature found (F5,560 = 0.72, p = .4)

Typical Equipment

• parafilm tubes
• glycol-water mixture
• Julabo F32-HL chamber

Output Measurements

• CTmin temperature
• chill coma recovery time

Papers Using This Protocol (1)

Species Studied With This Protocol