Tamm-Horsfall protein, a kidney marker is expressed on brain sulfogalactosylceramide-positive astroglial structures

The Tamm-Horsfall (TH) glycoprotein and the acidic glycosphingolipid sulfogalactosylceramide (SGC) have a strictly superimposable localization on kidney tissue sections. The fact that SGC is a prevalent glycolipid in mammalian brain, prompted us to look for the presence of TH in the rat central nervous system (CNS). An antiserum raised against human TH was found to react with rat CNS homogenate in the complement fixation assay. This anti-TH antiserum recognized a rat CNS protein having an identical electrophoretical mobility on SDS polyacrylamide gel electrophoresis (PAGE). Indirect immunofluorescence on rat brain tissue sections allowed us to localize this brain TH cross-reacting material to ependymal cells and astrocytic processes such as the Bergmann fibers or astrocytic feet in contact with either the blood vessels or the meninges. All these astroglial structures are also SGC-positive. Since TH and SGC in the kidney are localized on a membrane that possesses an electrogenic Cl-pump, we propose that the astroglial structures which contain these two molecules are also the site of a Cl-transport system.

Immunohistochemical localization of galactosyl and sulfogalactosyl ceramide in the brain of the 30-day-old mouse

We have used purified antibodies against galactosylceramide (galCb) and sulfogalactosylceramide (sulf) to study the topographical distribution of these two lipid haptens in the brain of the 30-day-old mouse. This study has been conducted, using the indirect immunofluorescence method, on cerebellum, brain stem and hemispherical tissue sections. Both haptens are present in the myelin sheaths and in the oligodendrocytes within the myelinated bundles. Cortical oligodendrocytes as well as some of the subependymal cells are also galCb-positive but sulf-negative. On the contrary, ciliated ependymal cells and subpial astrocytic processes (especially the Bergmann glia fibers in the cerebellum) are sulf-positive and galCb-negative. Astrocyte cell bodies and other astrocytic cell processes are devoid of both haptens. Lastly, some-sulf positive galCb-negative processes, as yet unidentified, were also found in the periaqueductal gray matter and in the nucleus interpeduncularis.

Determination of glial fibrillary acidic protein (GFAP) in human brain tumors

Brain tumors have been tested for their glial fibrillary acidic protein (GFAP) content by means of the rocket electrophoresis technique. Meningiomas and neurinomas were low in GFAP. Metastases had a low level of GFAP except when contaminated with surrounding tissue. Non-nervous tumors such as myeloma, myeloplaxoma and adenocarcinoma gave negative results. More detailed correlations with histological observations have been looked for in glial tumors. Low levels of GFAP were always associated with signs of malignancy such as mitoses and giant or atypical cells, whereas high levels of GFAP were correlated with the presence of well-preserved astrocytes.

Pelizaeus-Merzbacher disease: biochemical analysis of isolated myelin (electron-microscopy; protein, lipid and unsubstituted fatty acids analysis)

Analysis of myelin from a leukodystrophic brain was performed (Pelizaeus-Merzbacher disease, classical type). Myelin recovery was 7% of normal, when isolated by ultracentrifugation. Electron microscopy showed a great amount of loose lamellae, with less thick sheaths and periodicity close to normal. This myelin contains fewer lipids than normal, sphingolipids and plasmalogens being reduced. FAtty acids from phospholipids are essentially normal, however enols from plasmalogens are largely reduced. Purified sphingolipids (cerebrosides, sulfatides and sphingomyelin) present a considerable diminution in very long chain fatty acids; the ratio of very long chain fatty acids (over C18) on shorter chains is 1% of the normal value for saturated fatty acids and 2% for the monounsaturated homologues. Protein analysis showed that basic protein and proteolipids were reduced, Wolfgram proteins being relatively increased.

Lignoceric acid biosynthesis in the developing brain. Activities of mitochondrial acetyl-CoA-dependent synthesis and microsomal malonyl-CoA chain-elongating system in relation to myelination. Comparison between normal mouse and dysmyelinating mutants (quaking and jimpy)

Age-related changes in the activities of microsomal and mitochondrial elongating systems have been determined in mouse brain from birth to maturity. In microsomes, the components necessary for behenyl-CoA (docosanoly-CoA) elongation have been found to be NADPH and malonyl-CoA. In mitochondria, both NADH and NADPH are used and acetyl-CoA is the only donor of two-carbon-atoms unit. The synthesised fatty acids were identified by thin-layer and gas chromatography. The specific activity is higher in microsomes than in mitochondria. In microsomes, the specific activity for malonyl-Co-A incorporation reached a maximum at 15 - 20 days of age; this peak was not obtained in the Quaking and Jimpy mutants. The increase in enzyme activity (specific activity and total activity per brain) paralleled the myelin deposition. The activity of the mitochondrial system increases regularly during development: it is not correlated to myelination and it is not affected in the Quaking mutant. The interplay between microsomal and mitochondrial elongation systems is studied.

Mouse brain uptake and metabolism of stearic acid

After injection, labelled stearic acid is transported directly into the brain and incorporated into brain lipids without prior oxydation to acetate and resynthesis of fatty acids. Contamination by blood can be excluded. (The preparation contains all subcellular fraction except cytosol). The labelled stearic acid taken up is partly metabolized in the brain either by elongation or by degradation and in situ resynthesis of fatty acids. The activity in oleic acid and mono-unsaturated chains is hardly detectable. The labelled acids are incorporated into lipids or subcellular particles following characteristic kinetics, which show a diminution by 24 hours. When analysing the evolution of each lipid, it is shown that this profile is followed by phospholipids, but not by cerebrosides and free fatty acids. The formers are still increasing up to 50 hours, the latters are stable (suggesting a physical binding between membranes and free fatty acids). Thus nutrition is an important parameter for the synthesis of brain membranes as far as exogenous saturated fatty acids are needed.