Kuhn Donald E, O'Brien Kristin M, Crockett Elizabeth L
Department of Biological Sciences, Ohio University, Athens, Ohio; and.
Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska.
Am J Physiol Regul Integr Comp Physiol. 2016 Oct 1;311(4):R649-R657. doi: 10.1152/ajpregu.00188.2016. Epub 2016 Jul 27.
The family Channichthyidae or "icefishes" (suborder Notothenioidei) represents the only vertebrates lacking hemoglobin (Hb) as adults. Several icefish species also do not express cardiac myoglobin (Mb). We address how levels of proteins involved in iron (Fe) processing (transport, sequestration, and export) vary among white- and red-blooded notothenioids, and whether absence of Hb and/or Mb in channichthyids is accompanied by expansion of contents of Fe-binding proteins to protect against unchaperoned Fe. Levels of transferrin (Tf), ferritin (Ft), ceruloplasmin (Cp), and non-heme Fe were quantified in plasma, serum, and/or nonhematopoietic tissues (cardiac ventricle, skeletal muscle, and liver) from species of white-blooded (Chaenocephalus aceratus, Champsocephalus gunnari, Chionodraco rastrospinosus, Pseudochaenichthys georgianus) (the first two species not expressing Mb) and red-blooded (Notothenia coriiceps, Gobionotothen gibberifrons) notothenioids. We also measured levels of ascorbate (Asc), a mediator of Fe uptake. While plasma concentrations of Tf and tissue levels of Asc are similar among species, concentrations of plasma Asc are lower in white-blooded species. Concentrations of Ft and non-heme Fe and activities of Cp are also generally reduced in icefishes compared with red-blooded notothenioids. The presence of cardiac Mb in some icefish species does not appear to influence levels of proteins involved in Fe processing. To address further the question of Fe sequestration within a physiological context, we account for well-characterized differences in blood volume and heart mass among white- and red-blooded notothenioids. We report that total contents of plasma Tf are greater, while ventricle non-heme Fe is at least at parity in white- vs. red-blooded species.
南极冰鱼科或“冰鱼”（亚目南极鱼亚目）是唯一成年后缺乏血红蛋白（Hb）的脊椎动物。几种冰鱼物种也不表达心肌肌红蛋白（Mb）。我们研究了参与铁（Fe）处理（运输、螯合和输出）的蛋白质水平在白血和红血南极鱼亚目鱼类之间如何变化，以及南极冰鱼科中缺乏Hb和/或Mb是否伴随着铁结合蛋白含量的增加以防止游离铁的危害。对来自白血（裸头冰鱼、冈氏冰鱼、棘头南极冰鱼、乔治王岛拟冰鱼）（前两个物种不表达Mb）和红血（科氏南极鱼、吉氏南极鱼）南极鱼亚目鱼类的血浆、血清和/或非造血组织（心室、骨骼肌和肝脏）中的转铁蛋白（Tf）、铁蛋白（Ft）、铜蓝蛋白（Cp）和非血红素铁水平进行了定量。我们还测量了铁摄取介质抗坏血酸盐（Asc）的水平。虽然物种间血浆Tf浓度和组织Asc水平相似，但白血物种的血浆Asc浓度较低。与红血南极鱼亚目鱼类相比，冰鱼中的Ft和非血红素铁浓度以及Cp活性通常也较低。一些冰鱼物种中存在心肌Mb似乎不影响参与铁处理的蛋白质水平。为了在生理背景下进一步解决铁螯合问题，我们考虑了白血和红血南极鱼亚目鱼类在血容量和心脏质量方面已明确的差异。我们报告，白血物种的血浆Tf总含量更高，而心室非血红素铁在白血与红血物种中至少相当。
