Metabolic plasticity suggests increased resilience to climate variability in temperate compared to tropical lizards

Abstract

Altogether 3 Takydromus lizards across latitudes were acclimated under cold and warm temperatures for no less than 40 days, then the livers of 6 individuals under cold and warm treatments from each species were collected freshly and used for metabolite extraction. Metabolite analysis was conducted by OE Biotech (Shanghai, People’s Republic of China) in relative quantitation by GC-TOF-MS.The livers were homogenized and then ultrasound treated on ice. The homogenate was then centrifuged and the supernatant with polar metabolites of each sample was transferred to a 2 mL GC-MS vial, another 11 μL supernatant from each sample were pooled as QC sample. Then the samples were condensed, reconstituted in sequence for incubation and cooled at room temperature. A total of 10 μL FAMEs (Standard mixture of fatty acid methyl esters, C8-C16: 1 mg/mL, C18-C24: 0.5 mg/mL, in chloroform) was added to the QC sample, and then GC-TOF-MS analysis conducted.GC-TOF-MS analysis was performed using an Agilent 7890 gas chromatograph system coupled with a Pegasus HT time-of-flight mass spectrometer. The system utilized a DB-5MS capillary column coated with 5% diphenyl cross-linked with 95% dimethylpolysiloxane (30 m x 250 μm inner diameter, 0.25 μm film thickness; J&W Scientific, Folsom, CA, USA). A total of 1 μL aliquot of the analyte was injected in splitless mode. Helium was used as the carrier gas, the front inlet purge flow was 3 mL/min and the gas flow rate through the column was 1 mL/min. The initial temperature was kept at 50 °C for 1 min, then raised to 310 °C at a rate of 10 °C/min, then kept for 8 min at 310 °C. The injection, transfer line and ion source temperatures were 280, 270 and 220 °C, respectively.Mass spectrometry was conducted on a Pegasus HT time-of-flight mass spectrometer (LECO Chroma TOF PEGASUS HT, LECO, USA). The mass spectrometry data were acquired in full-scan mode with the mass range of 50-500 m/z at a rate of 20 spectra/s after a solvent delay of 455 s. The energy was -70 eV in electron impact mode. The acquired MS data were analyzed by Chroma-TOF software (v 4.34, LECO, St Joseph, MI).