Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, SP, Brazil.
Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, SP, Brazil
J Exp Biol. 2021 Feb 4;224(Pt 3):jeb233890. doi: 10.1242/jeb.233890.
Owing to their extraordinary niche diversity, the Crustacea are ideal for comprehending the evolution of osmoregulation. The processes that effect systemic hydro-electrolytic homeostasis maintain hemolymph ionic composition via membrane transporters located in highly specialized gill ionocytes. We evaluated physiological and molecular hyper- and hypo-osmoregulatory mechanisms in two phylogenetically distant, freshwater crustaceans, the crab and the shrimp , when osmotically challenged for up to 10 days. When in distilled water, survived without mortality, hemolymph osmolality and [Cl] increased briefly, stabilizing at initial values, while [Na] decreased continually. Expression of gill V-type H-ATPase (V-ATPase), Na/K-ATPase and Na/K/2Cl symporter genes was unchanged. In , hemolymph osmolality, [Cl] and [Na] decreased continually for 12 h, the shrimps surviving only around 15-24 h exposure. Gill transporter gene expression increased 2- to 5-fold. After 10 days exposure to brackish water (25‰S), was isosmotic, iso-chloremic and iso-natriuremic. Gill V-ATPase expression decreased while Na/K-ATPase and Na/K/2Cl symporter expression was unchanged. In (20‰S), hemolymph was hypo-regulated, particularly [Cl]. Transporter expression initially increased 3- to 12-fold, declining to control values. Gill V-ATPase expression underlies the ability of to survive in fresh water while V-ATPase, Na/K-ATPase and Na/K/2Cl symporter expression enables to confront hyper/hypo-osmotic challenges. These findings reveal divergent responses in two unrelated crustaceans inhabiting a similar osmotic niche. While does not secrete salt, tolerating elevated cellular isosmoticity, exhibits clear hypo-osmoregulatory ability. Each species has evolved distinct strategies at the transcriptional and systemic levels during its adaptation to fresh water.
由于甲壳动物的特殊生态位多样性，它们是理解渗透调节进化的理想选择。影响全身水盐动态平衡的过程通过位于高度特化的鳃离子细胞中的膜转运蛋白来维持血淋巴离子组成。我们评估了两种系统发育上相距较远的淡水甲壳动物——蟹和虾在渗透压挑战下长达 10 天的生理和分子高渗和低渗调节机制。在蒸馏水中， 能够存活而没有死亡率，血淋巴渗透压和 [Cl]短暂增加，稳定在初始值，而 [Na]持续下降。鳃 V 型 H+-ATP 酶 (V-ATPase)、Na/K-ATPase 和 Na/K/2Cl 协同转运蛋白基因的表达没有变化。在 中，血淋巴渗透压、[Cl]和 [Na]持续下降 12 小时，虾类只能存活约 15-24 小时。鳃转运蛋白基因表达增加 2-5 倍。在 10 天暴露于咸水中（25‰S）后， 是等渗、等氯和等钠的。鳃 V-ATPase 表达降低，而 Na/K-ATPase 和 Na/K/2Cl 协同转运蛋白表达不变。在 （20‰S）中，血淋巴被低渗调节，特别是 [Cl]。转运蛋白表达最初增加 3-12 倍，下降到对照值。鳃 V-ATPase 表达是 能够在淡水中生存的基础，而 V-ATPase、Na/K-ATPase 和 Na/K/2Cl 协同转运蛋白表达使 能够应对高渗/低渗挑战。这些发现揭示了两种亲缘关系较远的甲壳动物在栖息于相似渗透环境中时表现出的不同反应。虽然 不分泌盐，但能耐受升高的细胞等渗性，但 表现出明显的低渗调节能力。在适应淡水的过程中，每个物种在转录和系统水平上都进化出了独特的策略。
