Department of Biological Science, Faculty of Science, Shizuoka University, Shizuoka 422-8529, Japan.
Gen Comp Endocrinol. 2020 May 1;290:113396. doi: 10.1016/j.ygcen.2020.113396. Epub 2020 Jan 24.
Biological activities in ectothermic vertebrates depend to a great extent on ambient temperature. Adapting their biological systems to annual or short-term alterations in temperature may play an important role in thermal resistance or overwintering survival. Using SDS-PAGE and western blot, we examined plasma proteins in bullfrog (Rana catesbeiana) tadpoles that were seasonally acclimatized (winter vs. summer) or thermally acclimated (4 °C vs. 21 °C) and identified two season-responsive proteins. The first, transthyretin (TTR), is a plasma thyroid hormone distributor protein that was abundant in summer, and the second is a protein containing C-type lectin-like domain (CTLD) that was abundant in winter and cold acclimation of 4 weeks. Sequence analysis revealed that the C-terminal carbohydrate recognition domain of this CTLD protein (termed collectin X) was highly similar to those of the collectin family members, which participate in complement activation of the innate immune system; however, it lacked most of collagen-like domain. Among the hepatic genes involved in the thyroid system, ttr and dio3 were up-regulated, whereas thra and thrb were down-regulated, in summer acclimatization or warm acclimation. In contrast, the collectin X gene (colectx), as well as colect10 and colect11 in the collectin family involved in the innate immune system, were down-regulated during warm acclimation, although fcn2 in the ficolin family was up-regulated during summer acclimatization and warm acclimation. These findings indicate that seasonal acclimatization and thermal acclimation differentially affect some components of the thyroid and innate immune systems at protein and transcript levels.
变温动物的生物活性在很大程度上依赖于环境温度。使生物系统适应年度或短期温度变化可能在热抵抗或越冬生存中发挥重要作用。使用 SDS-PAGE 和 Western blot，我们检测了季节性驯化（冬季与夏季）或热驯化（4°C 与 21°C）的牛蛙（Rana catesbeiana）蝌蚪的血浆蛋白，并鉴定了两种对季节有反应的蛋白质。第一种是转甲状腺素蛋白（TTR），它是一种血浆甲状腺激素分配蛋白，在夏季丰富，第二种是富含 C 型凝集素样结构域（CTLD）的蛋白质，在冬季和 4 周的冷驯化中丰富。序列分析表明，该 CTLD 蛋白的 C 末端碳水化合物识别结构域（称为集落蛋白 X）与参与先天免疫系统补体激活的集落家族成员高度相似；然而，它缺乏大多数胶原样结构域。在参与甲状腺系统的肝脏基因中，ttr 和 dio3 在夏季驯化或温暖驯化中上调，而 thra 和 thrb 下调。相反，集落蛋白 X 基因（colectx）以及先天免疫系统中涉及的集落蛋白家族的 colect10 和 colect11 在温暖驯化期间下调，尽管 ficolin 家族的 fcn2 在夏季驯化和温暖驯化期间上调。这些发现表明，季节性驯化和热驯化在蛋白质和转录水平上对甲状腺和先天免疫系统的某些成分产生不同的影响。
