Metamorphic Changes in Glycolipids and Myelin Proteins and 2′,3′‐Cyclic Nucleotide 3′‐Phosphohydrolase in Bullfrog and Axolotl Brains

Abstract

The metamorphic changes in levels of glycolipids and myelin proteins and 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP) in the brains of bullfrog tadpoles, adult frogs, and axolotls were investigated, with particular emphasis on myelin maturation. The concentrations of cerebroside, sulfatide, and galactosyldiacylglycerol gradually increased from the onset of prometamorphosis throughout the active metamorphic period and then greatly increased after metamorphosis was completed. The ratio of glucocerebroside to galactocerebroside increased greatly in the prometamorphic period and then rapidly decreased to the frog level during the climax period. The fatty acid compositions of cerebroside and sulfatide showed a developmental change, with 24:1 being more predominant in the later metamorphic stage. The proportion of hydroxy fatty acids increased up to the onset of the prometamorphic stage and thereafter remained constant at approximately 50% of the total. The CNP activity remained unchanged throughout metamorphosis at 60% that in frog myelin and increased in the adult frog. The composition of tadpole myelin proteins remained constant during metamorphosis, with large basic protein being the most abundant, and in the frog, proteolipid protein and large basic protein were present in comparable amounts. The two adult forms of axolotl, i.e., the neotenous and metamorphosed forms, exhibited almost identical myelin constituents, and CNP activity in the neotenous form amounted to one-fifth that in the bullfrog. These results indicate that active biosynthesis of myelin marker components occurs as metamorphosis proceeds, but more pronounced changes of myelin components occur after metamorphosis is completed.

Transcriptional profiling reveals evidence for signaling and oligodendroglial abnormalities in the temporal cortex from patients with major depressive disorder

“…46 CNP encodes 2 0 ,3 0 -cyclic nucleotide 3 0 -phosphodiesterase, which plays a role in signaling pathways mediated by lipid-protein domains, 47 and is a commonly used marker of myelin. 48 ENPP2 encodes an ectonucleotide pyrophosphatase/phosphodiesterase 2 that may play a role during active myelination and/or late stages of oligodendrocyte differentiation, possibly through cell-cell and/or cell-extracellular matrix recognition. 49 EDG2 encodes a G-proteincoupled receptor involved in myelin formation or maintenance.…”

A Comparative Study of 2′,3′‐Cyclic‐Nucleotide 3′‐Phosphodiesterase in Vertebrates: cDNA Cloning and Amino Acid Sequences for Chicken and Bullfrog Enzymes

“…2 ',3 '-Cyclic-nucleotide 3 '-phosphodiesterase (CNP; EC 3.1.4.37) is found mainly in the CNS of vertebrates, especially of amphibia and higher vertebrates Tsukada, 1967, 1968;Tamai et al, 1993). On subcellular fractionation of mammalian brain, CNP is recovered mainly from the myelin fraction (Kurihara and Tsukada, 1967).…”