Institute of Neurobiology, Ulm University, Germany.
Institute of Evolutionary Ecology and Conservation Genomics, Ulm University, Germany.
FEBS Open Bio. 2022 Feb;12(2):443-459. doi: 10.1002/2211-5463.13350. Epub 2021 Dec 20.
The energy-saving strategy of Djungarian hamsters (Phodopus sungorus, Cricetidae) to overcome harsh environmental conditions comprises of behavioral, morphological, and physiological adjustments, including spontaneous daily torpor, a metabolic downstate. These acclimatizations are triggered by short photoperiod and orchestrated by the hypothalamus. Key mechanisms of long-term photoperiodic acclimatizations have partly been described, but specific mechanisms that acutely control torpor remain incomplete. Here, we performed comparative transcriptome analysis on hypothalamus of normometabolic hamsters in their summer- and winter-like state to enable us to identify changes in gene expression during photoperiodic acclimations. Comparing nontorpid and torpid hamsters may also be able to pin down mechanisms relevant for torpor control. A de novo assembled transcriptome of the hypothalamus was generated from hamsters acclimated to long photoperiod or to short photoperiod. The hamsters were sampled either during long photoperiod normothermia, short photoperiod normothermia, or short photoperiod-induced spontaneous torpor with a body temperature of 24.6 ± 1.0 °C, or. The mRNA-seq analysis revealed that 32 and 759 genes were differentially expressed during photoperiod or torpor, respectively. Biological processes were not enriched during photoperiodic acclimatization but were during torpor, where transcriptional and metabolic processes were reinforced. Most extremely regulated genes (those genes with |log2(FC)| > 2.0 and padj < 0.05 of a pairwise group comparison) underpinned the role of known key players in photoperiodic comparison, but these genes exhibit adaptive and protective adjustments during torpor. Targeted analyses of genes from potentially involved hypothalamic systems identified gene regulation of previously described torpor-relevant systems and a potential involvement of glucose transport.
沙鼠（Phodopus sungorus，仓鼠科）为克服恶劣环境条件而采取的节能策略包括行为、形态和生理上的调整，包括自发性日常蛰伏，即代谢下降状态。这些适应是由短光照周期和下丘脑协调触发的。长期光周期适应的关键机制已部分描述，但控制蛰伏的特定机制仍不完整。在这里，我们对处于夏季和冬季样态的代谢正常沙鼠的下丘脑进行了比较转录组分析，以使我们能够在光周期适应过程中识别基因表达的变化。比较非蛰伏和蛰伏沙鼠也可能能够确定与蛰伏控制相关的机制。从适应长光照周期或短光照周期的沙鼠中生成了下丘脑的从头组装转录组。在长光照周期正常体温、短光照周期正常体温或短光照周期诱导的自发性蛰伏（体温为 24.6±1.0°C）期间，对沙鼠进行采样。mRNA-seq 分析显示，在光周期或蛰伏期间分别有 32 和 759 个基因差异表达。在光周期适应过程中没有富集生物过程，但在蛰伏期间有，在蛰伏期间，转录和代谢过程得到加强。大多数极调控基因（那些基因的 |log2(FC)|>2.0 和成对组比较的 padj<0.05）支持了已知关键参与者在光周期比较中的作用，但这些基因在蛰伏期间表现出适应性和保护性调整。对潜在涉及下丘脑系统的基因进行的靶向分析确定了先前描述的与蛰伏相关系统的基因调控，并可能涉及葡萄糖转运。
