Establishment of heat stress resistance in <i>G</i>. <i>przewalskii</i> after exposure to mid-high temperature under further severe heat stress.

<p>(a) Schematic diagram of heat exposure experiment. <i>G</i>. <i>przewalskii</i> embryos were incubated at 16°C from fertilization to 192 hpf (hatching out). Larvae at 192 hpf were exposed to heat stress at 24°C (HS group) and the controls (CT group) were maintained at 16°C. Samples for RNA-seq and miRNA-seq were collected at 216 hpf. After a comparative treatment for 12 h, larvae from both groups were further exposed to severe heat stress (30°C) for 48 h. The heating rate is ~ 0.8°C per hour. Images of larvae were taken by using stereomicroscope from Zeiss SteREO DiscoveryV12 with a color CCD camera. Death rates of larvae from both groups were recorded respectively. (b) Bar plot indicates the death rates of larvae from HS and CT groups at different time. HS and CT groups were colored by orange and blue, respectively. Data was shown as mean ± standard error of the mean (n = 3). “**” above error bars indicate <i>p</i> < 0.01. (c) Samples from HS and CT groups were exposed to 30°C for 48 h. Image of larvae were also taken by using Zeiss SteREO DiscoveryV12. Red arrowheads indicate representative malformed and dead larvae.