The mannose receptor is expressed by olfactory ensheathing cells in the rat olfactory bulb.

Complex carbohydrate structures are essential molecules of infectious bacteria, parasites, and host cells and are involved in cell signaling associated with immune responses, glycoprotein homeostasis, and cell migration. The uptake of mannose-tailed glycans is usually carried out by professional phagocytes to trigger MHC class I- and MHC class II-restricted antigen presentation or, alternatively, to end inflammation. We have detected the mannose receptor (MR) in cultured olfactory ensheathing cells (OECs), so we investigated by flow cytometry whether recently dissociated cells of the olfactory bulb (OB) nerve fiber layer (ONL) could bind a mannosylated ligand (fluorescein conjugate of mannosyl bovine serum albumin; Man/BSA-FITC) in a specific manner. In addition, we estimated the relative proportion of ONL OECs, microglia, and astrocytes, tagged by 2'3'-cyclic nucleotide 3'-phosphodiesterase (CNPase), by the B4 isolectin of Griffonia simplicifonia (IB4), and by glial fibrillary acidic protein (GFAP), respectively, that were Man/BSA-FITC(+) . We also determined by histochemistry and/or immunohistochemistry whether Man/BSA-FITC or an anti-MR antibody (anti-C-terminal MR peptide; anti-cMR) labeled OECs and/or parenchymal microglia. In addition, we confirmed by Western blot with the K1K2 (against the entire MR molecule) antibody that a band of about 180 kDA is expressed in the OB. Our findings are compatible with a prospective sentinel role of OECs against pathogens of the upper airways and/or damage-associated glycidic patterns as well as with homeostasis of OB mannosylated glycoproteins.

Regionally specific distribution of the binding of anti-glutamine synthetase and anti-S100 antibodies and of Datura stramonium lectin in glial domains of the optic lobe of the giant prawn.

We previously characterized some crustacean glial cells by markers such as 2',3'-cyclic nucleotide 3'-phosphodiesterase and glial fibrillary acidic protein. Here we use antibodies against glutamine synthetase full-length molecule (anti-GS/FL), a GS C-terminal peptide (anti-GS/20aa-C), and brain S100 (anti-S100), as well as the binding of the insect glia and rat astrocytic marker Datura stramonium lectin (DSL), in the optic lobe of the prawn Macrobrachium rosenbergii. All markers label the lamina ganglionaris cartridge region (lighter: anti-GS/FL; heavier: DSL). In addition, anti-GS/FL labels superficial somata of external and internal medullas and internal chiasm cells. Both anti-GS/20aa-C and anti-S100 label heavily the glial sheaths of the lamina ganglionaris. In addition, anti-S100 binds to the perineurial glia of medullary parenchymal vessels. Western blot analyses show that both anti-GS/FL and anti-GS/20aa-C bind mostly to a band of 50-55 kDa, compatible with a long isoform of vertebrate GS, and accessorily to a possible dimer and, in the case of anti-GS/20aa-C, to an ill-defined band of intermediate mass. Binding of anti-S100 is selective for a single band of about 68 kDa but shows no protein in the weight range of the canonical S100 protein superfamily. DSL reveals two bands of about 75 and about 120 kDa, thus within the range of maximal recognition for rat astrocytes. Our results suggest that phenotype protein markers of the optic lobe glia share antigenic determinants with S100 and (a long form of) GS and that, similarly to vertebrate and insect glia, crustacean glia protein and N-glycan residue markers display regional heterogeneity.

Expression of 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) in the developing olfactory bulb and subventricular zone rostral extension.

The olfactory bulb (OB) presents a unique pattern of permanent acquisition of primary afferents and interneurons, but not much detail is known about the differentiation of its oligodendroglial cells. We studied the expression of 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase), a protein related to axonal ensheathment by myelinating cells. Expression of CNPase in OB follows a general caudorostral gradient, with the exception of the glomerular layer (GL). At postnatal day 5-6 (P5-P6), the first CNPase(+) profiles appeared in the dorsal lateral olfactory tract adjacent to the accessory OB (AOB), followed by rare cell bodies and processes in AOB internal plexiform layer at P7. At P9, the main OB (MOB) granular cell layer (GrCL) already showed intensely stained CNPase(+) processes. From P5 to P12, small numbers of CNPase(+) cells were found in the subventricular zone (SVZ), throughout its rostral extension (SVZ-RE), and in the intrabulbar subependymal layer. The appearance of CNPase(+) profiles delimiting glomeruli started in the GL rostralmost region at P12, extending to all GL levels, but glomeruli remained open caudally at P15. At P18, oligodendroglial glomeruli were evident throughout OB, but the adult pattern was established only after P30. There was no age-related loss of CNPase immunoreactivity in glial cell bodies, possibly indicating de novo ensheathment of neurites. Our results show an earlier onset of oligodendroglial differentiation in OB than previously reported and a rostrocaudal gradient of formation of oligodendroglial glomeruli. They also raise the possibility that a minor fraction of OB oligodendrocytes might derive from the SVZ-RE.

Lectin histochemistry of microglia in superior colliculus of the developing opossum

The development of microglia in the opossum superior colliculus (SC) has been studied by lectin histochemistry (Griffonia simplicifolia B4 isolectin, GsI/B4). Prior to the end of neurogenesis (by postconceptional day 26, PcD 26), there are virtually no GsI/B4+ cells in the SC parenchyma although rare roundish elements are found at the tectal and, in larger numbers, the tegmental border of the aqueduct. The appearance of microglia in the SC follows a ventrodorsal gradient, correlating with the direction of neurogenesis, cytomorphological differentiation and growth of the vascular network rather than with a leptomeningeal source, and without forecasting value for astroglial differentiation. In the superficial layers (sSC), relatively few but moderately ramified cells rather than macrophages coexist with regressive changes in retinocollicular axons (by PcD 39-53). By the end of and soon after this period, there is a striking increase in the number of fairly ramiried GsI/B4+ cells within the SC proper. Macrophages also become abundant but remain restricted to the vicinity of the aqueductal ependyma and are fewer at the tectal than at the tegmental aspect. These supraependymal macrophages as well as ramified parenchymal cells maintain the ability to divide at a low rate throughout maturation. The ingress via the aqueduct and cell proliferation may contribute to the complement of SC microglia but the major immediate source remains unknown.