Rising floor and dropping ceiling: organ heterogeneity in response to cold acclimation of the largest extant amphibian

Abstract

Low temperature imposes strong selective pressure on ectotherms. To maximize their overall fitness under cold conditions, the ectotherms may either try to maintain their physiological activities through metabolic compensation or enter into metabolic depression; however, some species adopt both strategies to cope with different degrees of cold. Nevertheless, how these two seemingly opposite strategies are coordinated has rarely been elucidated. Here, we investigated the molecular strategy underlying the cold acclimation of Andrias davidianus , the largest extant amphibian, using multi-organ metabolomics and transcriptomics. The results showed remarkable organ heterogeneity in response to cold. While most organs showed transcriptional upregulation of metabolic processes, the heart exhibited downregulation. This heterogeneity explained the adaptive reorganization in resource allocation, which compensates for metabolic maintenance by compromising growth. Importantly, the cardiac function might constitute a ‘ceiling’ to constrain the space for compensation, especially under colder conditions. Additionally, the opposite transcriptional regulation of oxidative phosphorylation and other pathways might also shape the overall metabolic capacity under cold conditions. The heterogeneity in cold responses may have directed a shift in cold adaptive strategy from compensation to depression with a drop in temperature. These results provide a novel insight into the regulatory mechanisms underlying cold survival strategies of ectotherms.

Albinism in the largest extant amphibian: A metabolic, endocrine, or immune problem?

“…RNA-seq was performed on an Illumina HiSeq 4000 platform by Annoroad (Beijing); paired-end reads were generated. A previously-reported multi-organ whole-length transcriptome was used as the reference genome for transcript identification, annotation, and gene expression quantification ( 24 ), and FPKM values were calculated for each unigene (see gene expression matrix in Table S1 ). This approach may improve the accuracy and reliability of the transcriptional quantification in comparison to a de novo assembly approach.…”

Validation of Salamander Dermal Mucus Swabs as a Novel, Nonlethal Approach for Amphibian Metabolomics and Glutathione Analysis Following Pesticide Exposure

“…To date, dermal swabs have been used in amphibians for DNA collection (Prunier et al, 2012) and disease profiling for two chytridiomycosis species: Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal), as well as frogvirus 3-like ranavirus (FV3; Standish et al, 2018). Mucosal sampling has been validated as a viable technique for metabolomic profiling in fish (Ekman et al, 2015), as well as peptide (reviewed in Barros et al, 2022), amino acid (Dejing, 2010;Rickrode et al, 1986), and transcriptomic analyses in amphibians (Zhu et al, 2022(Zhu et al, , 2023. However, a comparison of the metabolomic profile from full-body dermal swabs relative to hepatic tissue samples among amphibians following exposure to a chemical stressor has not yet been published.…”