HSP70 localization in Podarcissiculus embryos under natural thermal regime and following a non-lethal cold shock

Differential Mitochondrial Genome Expression of Three Sympatric Lizards in Response to Low-Temperature Stress

Ecological factors related to climate extremes have a significant influence on the adaptability of organisms, especially for ectotherms such as reptiles that are sensitive to temperature change. Climate extremes can seriously affect the survival and internal physiology of lizards, sometimes even resulting in the loss of local populations or even complete extinction. Indeed, studies have shown that the expression levels of the nuclear genes and mitochondrial genomes of reptiles change under low-temperature stress. At present, the temperature adaptability of reptiles has rarely been studied at the mitochondrial genome level. In the present study, the mitochondrial genomes of three species of lizards, Calotes versicolor, Ateuchosaurus chinensis, and Hemidactylus bowringii, which live in regions of sympatry, were sequenced. We used RT-qPCR to explore the level of mitochondrial gene expression under low-temperature stress, as compared to a control temperature. Among the 13 protein-coding genes (PCGs), the steady-state transcript levels of ND4L, ND1, ATP6, and COII were reduced to levels of 0.61 ± 0.06, 0.50 ± 0.08, 0.44 ± 0.16, and 0.41 ± 0.09 in C. versicolor, respectively, compared with controls. The transcript levels of the ND3 and ND6 genes fell to levels of just 0.72 ± 0.05 and 0.67 ± 0.05 in H. bowringii, compared with controls. However, the transcript levels of ND3, ND5, ND6, ATP6, ATP8, Cytb, and COIII genes increased to 1.97 ± 0.15, 2.94 ± 0.43, 1.66 ± 0.07, 1.59 ± 0.17, 1.46 ± 0.04, 1.70 ± 0.16, and 1.83 ± 0.07 in A. chinensis. Therefore, the differences in mitochondrial gene expression may be internally related to the adaptative strategy of the three species under low-temperature stress, indicating that low-temperature environments have a greater impact on A. chinensis, with a small distribution area. In extreme environments, the regulatory trend of mitochondrial gene expression in reptiles is associated with their ability to adapt to extreme climates, which means differential mitochondrial genome expression can be used to explore the response of different lizards in the same region to low temperatures. Our experiment aims to provide one new research method to evaluate the potential extinction of reptile species in warm winter climates.

Acute temperature adaptation mechanisms in the native reptile species Eremias argus

Reptiles are sensitive to temperature changes as ectotherm animals. The climate warming may pose more serious threat to reptiles. Although the behavior effect and reproduction biology have been well studied, little information is available about the adaptation mechanisms of reptiles to temperature stress. In this study, the native Chinese species, Eremias argus were incubated at 15 (cold stress), 25 (control group) and 35 °C (thermal stress) for 24 h. The transcriptome and metabolome technology were applied to investigate the molecular regulation mechanisms of lizards to acute temperature changes. The CIRBP and HSPA8 were hub genes in response to temperature adaptation. The increased expression of PER gene in lizard circadian rhythm is associated with tyrosine metabolism after cold or thermal stress. The poly-unsaturated fatty acids in female lizard liver were significantly increased with up-regulation of FASN and ACACA genes after thermal stress, which proved the disruption of fatty acid biosynthesis pathway in corporation with the altered body weight. The cortisol and testosterone were important steroid hormones in response to temperature changes especially in male lizard liver. The increased CIRBP gene expression in lizard gonads suppressed the KDM6B gene, which regulates the testis development and may induce sex reversal in male lizard after thermal stress. The adaptation responses of lizards to temperature stress may threaten the health status of wild population.