Levels of sulfatide synthesis distinguish oligodendroglia in different stages of maturation

In the central nervous system, oligodendroglia elaborate extensive quantities of membranes to form the multilamellar myelin sheath. Whether the production of extensive networks of processes by oligodendroglia in culture is a similar type of phenomenon as the formation of myelin is an unanswered question. Rat oligodendroglia, prepared by a modification of a differential shaking and plating method, elaborate extensive processes in culture. In contrast, bovine oligodendroglia, obtained by a bulk-isolation method, produce whorls of membrane lamellae, adjacent to the cell soma. The incorporation of various radiolabeled substrates into specific lipids was compared with the two cell types. It was found that rat oligodendroglia do produce myelin specific lipids, but at a lower level than bovine oligodendroglia which are actively synthesizing myelin lipids, especially cerebrosides, from a variety of substrates. Interestingly sulfatides are produced at a higher level in the cells not producing myelin, rat oligodendroglia. Other lipids that are associated with myelination (cerebrosides with -hydroxy fatty acids and phosphatidylinositides) are produced at higher levels in bovine oligodendroglia. Thus it appears that the extension of processes by oligodendroglia in culture is a different phenomenon than the production of myelin membranes and requires lower levels of myelin lipids.     

Electron microscopic and cytochemical research on the function of the glial cells in a focus of local cortical destruction

The activity of DNA-RNA-protein synthesizing system of some glial cells was studied using electron cytochemical method for determination of chromatin state and RNA-particles. A dependence of functional state of satellite glial cells (oligodendroglia and astroglia) on the tinctorial neuron state (hyper- and hypochromic scale) was shown. The functional state of interfascicular oligodendroglial cells has been characterized.     

Biochemical and histochemical study on the intestinal mucosa of the common carp Cyprinus carpio L., with special consideration of mucin glycoproteins

The biochemical and histochemical properties of intestinal mucin glycoproteins of virus and parasite-free common carp Cyprinus carpio were investigated. The presence of carbohydrates in mucin glycoproteins could be demonstrated by histochemical methods, but generally, no obvious differences in specific staining for mucin glycoproteins were observed in contrast to biochemical techniques. Biochemical staining methods displayed differences in structure and composition of intestinal glycoproteins. Released intestinal glycoproteins contained two types of mucin glycoproteins: type 1 mucins displayed a size of >2000 kDa, and were highly glycosylated, while type 2 mucins ranged between 700 and 70 kDa, and were weakly glycosylated. In epithelial (intracellular) glycoproteins, mainly N-acetyl-α-galactosamine and mannose were found, while in luminal (extracellular) glycoproteins in addition sialic acid was evident. Fucose was not detected. Thus, structure and composition of intestinal glycoproteins of common carp were similar to those found in mammals.     

The histochemistry of complex carbohydrates in the testes of patients of idiopathic male infertility

Summary In testis tissues from patients with idiopathic male infertility, complex carbohydrates have been studied by means of light microscopic histochemical methods, comparisons being made with the normal testes. In the infertile testes, histochemical reactions for acidic and neutral complex carbohydrates were in general weaker in intensity than in the normal testes. In the seminiferous tubules and interstitium of the infertile testes, a histochemical finding of primary importance was obtained with the demonstration of galactose deficiency in the complex carbohydrates involved. These glycoproteins contained only small numbers of sulfhydryl and disulfide groups. The possible histophysiological significance of these complex carbohydrates is discussed, with special reference to their histochemical properties determined in the present study.     

The histochemistry of complex carbohydrates in the testes of patients of idiopathic male infertility.

In testis tissues from patients with idiopathic male infertility, complex carbohydrates have been studied by means of light microscopic histochemical methods, comparisons being made with the normal testes. In the infertile testes, histochemical reactions for acidic and neutral complex carbohydrates were in general weaker in intensity than in the normal testes. In the seminiferous tubules and interstitium of the infertile testes, a histochemical finding of primary importance was obtained with the demonstration of galactose deficiency in the complex carbohydrates involved. These glycoproteins contained only small numbers of sulfhydryl and disulfide groups. The possible histophysiological significance of these complex carbohydrates is discussed, with special reference to their histochemical properties determined in the present study.     

Oligodendroglial Signal Transduction Systems Are Developmentally Regulated

Abstract: Studies from several laboratories indicate that oligodendroglia exhibit signal transduction systems that can be activated by classical neurotransmitters. Previous studies from this laboratory indicate that oligodendroglia express neuroligand receptors linked to the regulation of Ca²⁺_i. Experiments presented in this article were designed to determine if developmental processes that influence the ability of oligodendroglia to respond to neuroligands with an increase in Ca²⁺_i proceed either in vitro or in vivo. Findings support the view that developmental processes markedly affected the sensitivity of these cells to both purinergic and cholinergic receptor agonists, whereas their responsiveness to either histamine or bradykinin appeared relatively stable over time. Approximately 90 and 75% of oligodendroglia responded to ATP or carbachol, respectively, after 4 days in vitro, whereas <10% of these cells responded to either of these neuroligands after 8 days in vitro. The decrease in the percentage of oligodendroglia responding to ATP, but not carbachol, could be prevented by including dibutyryl cyclic AMP in the culture medium during the final 4 days in vitro. However, once the loss in responsiveness to ATP had occurred, it could not be reversed by exposure to dibutyryl cyclic AMP. Developmental changes in the ATP sensitivity of oligodendroglia occurred in cells expressing galactocerebroside and myelin basic protein. The neuroligand sensitivity of oligodendroglia isolated from either neonatal, 2-, 3-, or 5-week-old spinal cord was examined to determine if developmental changes in oligodendroglial Ca²⁺ regulation occurred in vivo. The results of these experiments indicate that the percentage of oligodendroglia responding to either ATP or carbachol markedly decreased as a function of the age of the animal used to prepare the cultures; this was not the case for the stimulation of Ca²⁺_i by histamine. The decreased sensitivity of oligodendroglia isolated from older animals could not be reversed through the addition of dibutyryl cyclic AMP. Overall, the results of these experiments indicate that developmental processes selectively influence the sensitivity of oligodendroglia to specific neuroligands and suggest that oligodendroglial processes unrelated to myelin formation may be regulated by neuroligands in vivo.     

STALOSYLGALACTOSYL CERAMTDE AS A SPECIFIC MARKER FOR HUMAN MYELIN AND OLIGODENDROGLIAL PERIKARYA: GANGLIOSIDES OF HUMAN MYELIN, OLIGODENDROGLIA AND NEURONS

Gangliosides were isolated from human brain myelin, oligodendroglia, and neurons. Quantitative analysis revealed the following ganglioside contents: myelin, 2.0; neurons, 1.3; and oligodendroglia, 0.35 μg ganglioside sialic acid per mg protein. Myclin had a relatively simple ganglioside pattern with G_M4 and G_M1 as the predominant ganglioside species. The ganglioside pattern of oligodendroglia was quite complex and it resembled that of whole white matter rather than that of myelin. A high concentration of G_M4 was found in oligodendroglial fractions in addition to G_M1, G_D1a, G_D1b, and G_T1b. The usually- minor brain gangliosides G_M3, G_M2, and G_M3 were also enriched in oligodendroglia. The neuronal ganglioside pattern was generally similar to the pattern of whole gray matter. Both neurons and whole gray matter contained very low amounts of G_M4. These results indicate that G_M4 is specifically localized in myelin and oligodendroglia of the CNS. Evidence is also presented that myelin, but not oligodendroglia, is the major reservoir of human white matter G_M1 and G_M4.     

Morphometrics of the avian small intestine compared with that of nonflying mammals: a phylogenetic approach

Flying animals may experience a selective constraint on gut volume because the energetic cost of flight increases and maneuverability decreases with greater digesta load. The small intestine is the primary site of absorption of most nutrients (e.g., carbohydrates, proteins, fat) in both birds and mammals. Therefore, we used a phylogenetically informed approach to compare small intestine morphometric measurements of birds with those of nonflying mammals and to test for effects of diet within each clade. We also compared the fit of nonphylogenetic and phylogenetic models to test for phylogenetic signal after accounting for effects of body mass, clade, and/or diet. We provide a new MATLAB program (Regressionv2.m) that facilitates a flexible model-fitting approach in comparative studies. As compared with nonflying mammals, birds had 51% less nominal small intestine surface area (area of a smooth bore tube) and 32% less volume. For animals <365 g in body mass, birds also had significantly shorter small intestines (20%-33% shorter, depending on body mass). Diet was also a significant factor explaining variation in small intestine nominal surface area of both birds and nonflying mammals, small intestine mass of mammals, and small intestine volume of both birds and nonflying mammals. On the basis of the phylogenetic trees used in our analyses, small intestine length and nominal surface area exhibited statistically significant phylogenetic signal in birds but not in mammals. Thus, for birds, related species tended to be similar in small intestine length and nominal surface area, even after accounting for relations with body mass and diet. A reduced small intestine in birds may decrease the capacity for breakdown and active absorption of nutrients. Birds do not seem to compensate for reduced digestive and absorptive capacity via a longer gut retention time of food, but we found some evidence that birds have an increased mucosal surface area via a greater villus area, although not enough to compensate for reduced nominal surface area. We predict that without increased rate of enzyme hydrolysis and/or mediated transport and without increased passive absorption of water-soluble nutrients, birds may operate with a reduced digestive capacity, compared with that of nonflying mammals, to meet an increase in metabolic needs (i.e., a reduced spare capacity).     

Distribution of metabolic activity (cytochrome oxidase) and immunoreactivity to calcium-binding proteins in the turtle brainstem auditory nuclei

Using histochemical and immunohistochemical techniques, distribution of activity of oxidative mitochondrial enzyme cytochrome oxidase (CO) and calcium-binding proteins-immunoreactivity was studied in the spiral ganglion and auditory nuclei of brainstem in two turtle species. Calbindin-, parvalbumin-and calretinin-immunoreactivity in neurons and neuropil of cochlear, supraolivary complexes, the lateral lemniscal nucleus and neuropil of spiral ganglion is shown to coincide topographically with high activity of CO. Similarity of the studied metabolic and neuro-chemical characteristics of these auditory centers in reptiles, birds and mammals suggests some general principles of their organization in amniotes, despite phylogenetic differences and peculiarities of auditory system in different species.     

Disturbance of lipid composition in spinal cord of rabbits with experimental allergic encephalomyelitis

EAE in rabbits was induced by means of inocculation of purified myelin of homologous spinal cord with complete Freund's adjuvant. The content of all the major lipid classes was studied by biochemical and histochemical methods in the different parts of spinal cord and in the brain stem in combination with morphological control for the demyelinating process presence. The most expressed myelin damage was found in the lumbar and sacral parts of spinal cord. In the same parts the content of phospholipids, cerebrosides, and free cholesterol decreased and cholesterol esters were shown to accumulate. Histochemical analysis supported these findings and revealed that the loss of lipids occured directly in the demyelination foci. Changes in total ganglioside content and in ganglioside fractions ratio were not observed. In the brain stem neither morphological, nor biochemical changes were found. On the basis of these data it was concluded that pathological processes of periaxonal demyelination, induced by the sensitization with purified myelin, have not damaged neuronal structures and not involved the brain.Special Issue dedicated to Dr. Eugene Kreps.     

UDP-Galactose:Ceramide Galactosyl Transferase of Isolated Oligodendroglia

Abstract: The activity of UDP-galactose:ceramide galactosyl transferase (CGalT) has been studied in isolated oligodendroglia from bovine brain white matter and myelinating rat brain. The specific activity and activity per mg DNA are 4- and 10-fold higher in rat oligodendroglia compared with neuronal perikarya from rat brain, and is higher in oligodendroglia from myelinating rat brain compared with bovine oligodendroglia. In membranes isolated from oligodendroglia, the specific activity decreased in the order endoplasmic reticulum > plasma membrane > myelin.     

Histochemical characteristics of the epitheliocytes of the avian glandular stomach

A complex histochemical investigation has been undertaken to study the epithelial lining of the glandular stomach in birds having various types of nutrition. The protective barrier of the avian stomach has been found to be characterized as a resistant (mucosal) barrier, with neutral glycoproteins, sialo- and sulphoglycoproteins as its components. Differences in histochemical properties of the epitheliocyte secretion have been described in birds with different types of nutrition. They are connected with various correlation of carbohydrates and proteins in the composition of the micromolecular glycoprotein complex. The data obtained are compared with those concerning the histochemical properties of the stomach in amphibia and reptiles which have the mucous membrane structure similar to that in the avian stomach.     

Biosynthesis of long chain fatty acids by oligodendroglia isolated from bovine white matter.

Abstract— Radioactively labelled fatty acids were incubated with interfascicular oligodendroglial preparations isolated from 9 month fetal and adult bovine CNS white matter to study their metabolism by these cells. Of the various acids studied, the uptake was greatest for palmitic acid and decreased with decreasing chain length. Laurie acid was converted to the greatest extent to other fatty acids. The incorporation of oleic and linoleic acids in the oligodendroglia from both the fetal and adult brains was higher than that of linolenic acid. Fatty acids underwent chain elongation, desaturation and oxidation. Oleic acid was elongated to nervonic acid. Fatty acids were incorporated into both cerebrosides and phospholipids, with preferential incorporation into ethanolamine phosphoglyceride.     

Peripheral Nervous System Myelin and Schwann Cell Glycoproteins: Identification by Lectin Binding and Partial Purification of a Peripheral Nervous System Myelin-Specific 170,000 Molecular Weight Glycoprotein

Radioiodinated lectins were used to detect glycoproteins of peripheral nervous system (PNS) myelin (rat, human, bovine) and cultured rat Schwann cells. Proteins were resolved by sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis and transferred to nitrocellulose filters. The filters were overlaid with radioiodinated lectins of known saccharide affinities. These included concanavalin A, Helix pomatia, Limulus polyphemus, Maclura pomifera, peanut, soybean, Ulex europaeus, and wheat germ agglutinins. Inclusion of the appropriate monosaccharide in the overlay solution (0.2 M) inhibited lectin binding to the nitrocellulose-fixed proteins. Fluorography permitted identification of 26 myelin glycoproteins and many more in Schwann cells. All lectins labeled a band present in myelin, but not Schwann cells, corresponding to the major PNS myelin protein, P0. Our attention focused on a high-molecular-weight myelin glycoprotein [apparent molecular weight (Mr) 170,000], which appeared abundant by Coomassie Blue staining and which was heavily labeled by all lectins except concanavalin A. A protein with approximately this Mr and lectin-binding pattern was present in human and bovine PNS myelin as well, but not detected in rat Schwann cells, CNS myelin, liver and fibroblast homogenates, or cultured bovine oligodendroglia. Hence this 170,000 Mr glycoprotein is apparently unique to PNS myelin.     

Proliferation and differentiation potential of rat forebrain oligodendroglial progenitors both in vitro and in vivo

We have followed the development of the O-2A progenitor cell from the neonatal rat forebrain, both in dissociated cell culture and in cryostat sections, using immunocytochemical techniques employing a panel of antibodies that recognise the cells at different stages of their development. This included the monoclonal antibody LB1, which binds to the surface ganglioside GD3 expressed on O-2A progenitor cells. In secondary cultures enriched for O-2A progenitors maintained in a serum-free chemically defined medium, a large proportion of the cells are primed to differentiate into oligodendroglia and go on to express the oligodendroglial specific surface glycolipid galactocerebroside (GC) and then the myelin proteins CNP and MBP. However, a significant proportion of immature bipolar GD3+ cells remained after 6 days in secondary culture. It appears that not all the O-2A progenitors in our cultures differentiate immediately and some cells remain in an undifferentiated state and divide to replenish progenitor numbers. We have also identified in our cultures a small apolar GD3- cell, which when isolated differentiated into a GD3+ bipolar O-2A progenitor cell. We have termed this cell type a preprogenitor. The differentiation of this cell type into O-2A progenitors may be the source of the immature GD3+ cells present at the later stages of our secondary cultures. The proliferative profile of the cultures was studied using 5'bromo-2-deoxyuridine (BrdU) incorporation as an index of mitosis. Only the immature, bipolar O-2A progenitors were seen to divide at any time in serum-free culture. Neither the more mature multipolar O-2A cells nor the oligodendroglia were seen to divide. The developmental profile of the O-2A cells in the rat forebrain in vivo showed a largely similar progression to that in culture, with a time lag of at least 6 days between GD3 expression and the onset of myelination. BrdU incorporation studies in vivo also showed that the GD3+ progenitor cell is mitotic whereas the GC(+)-expressing oligodendroglia is not. We have shown that there are several significant alterations in the timing of antigen expression in both O-2A progenitors and oligodendroglia in vitro compared to that seen in vivo.     

Glycohistochemistry of the Tilapia spp. stomach

A histochemical study using conventional and lectin methods was performed on the stomach of fasting and feeding adults of Tilapia spp. A battery of HRP-conjugated lectins combined with exoglycosidase digestion was used. The differences found in the epithelium, gastric pits and gastric glands between fasting and feeding subjects were related to the functional stages of the organ. Carbohydrate composition was also compared with that of mammals and birds.     

The histochemistry of complex carbohydrates in the epithelium lining the ventral prostate of the rat

Summary In the epithelium lining the ventral prostate of the rat, complex carbohydrate-containing structures have been studied by means of both light and electron microscopic histochemical methods. According to light microscopy, the free surface and granules of different sizes in the distal cytoplasm of the epithelial cells were found to exhibit positive reactions for complex carbohydrates with 1,2-glycol and acidic groups and sialic acid residues. In addition, secretory substances within the glandular lumen were shown to exhibit positive reactions for similar groups and saccharide residues of complex carbohydrates. In electron microscopy, the surface coat of the plasma membrane, certain elements of the Golgi apparatus and lysosomal dense bodies were found to exhibit positive reactions for glycoproteins with 1,2-glycol groupings. The histophysiological significances of the carbohydrate-containing structures have been discussed with special reference to the known physiological functions of the prostate in the rat.     

Melano-macrophage centres in liver and spleen of ruffe(Gymnocephalus cernua) from the Elbe Estuary

Macrophages with yellow or black deposits of melanin occur singly or in groups in the melano-macrophage centres are functionally the primitive analogues of lymph nodes in birds and mammals. From 1980 to 1982, tumours and pretumorous tissue changes in ruffe from the Elbe Estuary were studied. Pathological alterations occur mainly in the liver and spleen. In connection with both, neoplastic abnormalities in liver and spleen, and fatty degenerative processes in the liver, an obvious increase in number and size of the melano-macrophage centres was observed. The colour, structure and some histochemical properties of melano-macrophage centres in the liver differ somewhat from those in the spleen. The majority of splenic centres were filled with large amounts of haemosiderin, whereas many hepatic macrophages contained fatty inclusions. Possible differences in the functions of splenic and hepatic melano-macrophage centres are discussed.     

Early Proliferation Does Not Prevent the Loss of Oligodendrocyte Progenitor Cells during the Chronic Phase of Secondary Degeneration in a CNS White Matter Tract

Partial injury to the central nervous system (CNS) is exacerbated by additional loss of neurons and glia via toxic events known as secondary degeneration. Using partial transection of the rat optic nerve (ON) as a model, we have previously shown that myelin decompaction persists during secondary degeneration. Failure to repair myelin abnormalities during secondary degeneration may be attributed to insufficient OPC proliferation and/or differentiation to compensate for loss of oligodendrocyte lineage cells (oligodendroglia). Following partial ON transection, we found that sub-populations of oligodendroglia and other olig2+ glia were differentially influenced by injury. A high proportion of NG2+/olig2–, NG2+/olig2+ and CC1−/olig2+ cells proliferated (Ki67+) at 3 days, prior to the onset of death (TUNEL+) at 7 days, suggesting injury-related cues triggered proliferation rather than early loss of oligodendroglia. Despite this, a high proportion (20%) of the NG2+/olig2+ OPCs were TUNEL+ at 3 months, and numbers remained chronically lower, indicating that proliferation of these cells was insufficient to maintain population numbers. There was significant death of NG2+/olig2– and NG2−/olig2+ cells at 7 days, however population densities remained stable, suggesting proliferation was sufficient to sustain cell numbers. Relatively few TUNEL+/CC1+ cells were detected at 7 days, and no change in density indicated that mature CC1+ oligodendrocytes were resistant to secondary degeneration in vivo. Mature CC1+/olig2– oligodendrocyte density increased at 3 days, reflecting early oligogenesis, while the appearance of shortened myelin internodes at 3 months suggested remyelination. Taken together, chronic OPC decreases may contribute to the persistent myelin abnormalities and functional loss seen in ON during secondary degeneration.