Gene transcription of neuroglobin is upregulated by hypoxia and anoxia in the brain of the anoxia-tolerant turtle Trachemys scripta.
Neuroglobin is a heme protein expressed in the vertebrate brain in mammals, fishes, and birds. The physiological role of neuroglobin is not completely understood but possibilities include serving as an intracellular oxygen-carrier or oxygen-sensor, as a terminal oxidase to regenerate NAD(+) under anaerobic conditions, or involvement in NO or ROS metabolism. As the vertebrate nervous system is particularly sensitive to hypoxia, an intracellular protein that helps sustain cellular respiration would aid hypoxic survival. However, the regulation of Neuroglobin (Ngb) under conditions of varying oxygen is controversial. This study examines the regulation of Ngb in an anoxia-tolerant vertebrate under conditions of hypoxia and anoxia. The freshwater turtle Trachemys scripta can withstand complete anoxia for days, and adaptations that permit neuronal survival have been extensively examined. Turtle neuroglobin specific primers were employed in RT-PCR for determining the regulation of neuroglobin mRNA expression in turtles placed in normoxia, hypoxia (4 h), anoxia (1 and 4 h), and anoxia-reoxygenation. Whole brain expression of neuroglobin is strongly upregulated by hypoxia and post-anoxic-reoxygenation in T. scripta, with a lesser degree of upregulation at 1 and 4 h anoxia. Our data implicate neuroglobin in mediating brain anoxic survival.
Milton
Sarah L
SL
Department of Biological Sciences SC 281, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431, USA. smilton@fau.edu
Nayak
Gauri
G
Lutz
Peter L
PL
Prentice
Howard M
HM
D000704:Analysis of Variance; D000818:Animals; D017931:DNA Primers; D005786:Gene Expression Regulation; D005914:Globins / Q000235:genetics / Q000378:metabolism*; D002534:Hypoxia, Brain / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D000078787:Neuroglobin; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014158:Transcription, Genetic / Q000502:physiology*; D014426:Turtles / Q000235:genetics / Q000502:physiology*
D017931:DNA Primers; D009419:Nerve Tissue Proteins; D000078787:Neuroglobin; D005914:Globins