[Lectin histochemistry of choroidal malignant melanoma]

Tumor specimens of malignant choroidal melanoma from a 50 year-old man were studied with reference to labeling with fluorescence-labeled lectins: wheat germ agglutinin (WGA), specific for sialic acid and N-acetylglucosamine, and Ricinus communis agglutinin-1 (RCA-1), specific for galactose. Epithelioid cells occupying the apex and internal portion of a dome-shaped tumor had intense labeling of WGA but little binding to RCA-1. Spindle-shaped cells in the base of the tumor were labeled moderately with WGA and faintly with RCA-1. Neuraminidase treatment of the specimens led to a marked increase in the RCA-1 binding to both epithelioid and spindle-shaped tumor cells. The results suggest association of the malignancy of choroidal melanoma cells with oligosaccharides of cell membrane-bound glycoconjugates.

Developmental change of distribution of beta-galactoside alpha 2,6-sialyltransferase mRNA in rat retina

A substantial change in the glycoconjugates of the rat interphotoreceptor matrix (IPM) has recently been shown to occur between post-natal day (P) 14 and P16 in rat retinas using lectin histochemistry. This suggests that the sialic acid content on the terminus of N-glycoside linked carbohydrate chains of the IPM increases between P14 and P16. In the present study, to test this hypothesis, we examined the developmental change of distribution of beta-galactoside alpha 2,6-sialyltransferase mRNA in rat retina using in situ hybridization histochemistry. C-DNA of rat alpha 2,6-sialyltransferase was isolated by PCR and cloned into the polylinker site of Bluescript KS (+). Antisense and sense RNA probes were labelled with digoxigenin-UTP by in vitro transcription with T3 and T7 RNA polymerases, respectively. Paraffin sections of rat retinas between P12 and P42 were incubated with the antisense or sense RNA probes. Specific labelling with the antisense probe was observed strongly in the cytoplasm of all ganglion cells and weakly in partial cells of the inner nuclear layers throughout the examined postnatal days. A remarkable change was observed in the photoreceptor cells between P14 and P16. Hybridization signals of the outer nuclear layer was observed from P14, while those of the inner segments were detected on P16 and thereafter. The alpha 2,6-sialyltransferase newly expressed in the inner segments on P16 appears to sialylate the Gal beta 1, 4GlcNAc residue of N-glycosidically linked glycoconjugates of the IPM, resulting in the change of lectin staining profiles.

[Light response of the interphotoreceptor matrix in inherited degenerative retina]

The light-evoked distributional changes of the interphotoreceptor matrix (IPM) in mice with three types of inherited retinal degeneration were examined by histochemistry using fluorescence isocyanate-labeled wheat germ agglutinin. In mice with nervous and Purkinje cell degeneration, the light response of the IPM was still somewhat preserved during the early stage of photoreceptor degeneration, whereas it became extinct when the outer segments (OS) became moderately or markedly shortened. In mice with slow retinal degeneration mice without development of OS, the light response of the IPM was absent throughout the developmental stages. These findings suggest that the presence of normal OS is necessary for the light response of the IPM to occur.

Interphotoreceptor matrix in the colored-light-adapted rat

The interphotoreceptor matrix (IPM) was examined histochemically using colloidal iron, wheat germ agglutinin and Ricinus communis agglutinin-1 for rats adapted to blue, green or red light before tissue preparation. In blue- and green-light-adapted animals, IPM was intensely stained in the apical zone of photoreceptor outer segments and in the outer and inner segment junction, conforming to the light pattern of IPM distribution in previous studies. In red-light-adapted animals, the IPM was prominent and uniform in the interstitial zone of photoreceptor outer segments, consistent with the dark pattern. The results indicate that rod photoreceptors are predominantly responsible for light-evoked changes in IPM.

[Aging effects on the light response of the interphotoreceptor matrix as revealed by binding of Ricinus communis agglutinin-1]

This study intended to explore whether the light response of the interphotoreceptor matrix (IPM) is affected by aging. The binding pattern of fluorescence-labeled Ricinus communis agglutinin-1 (RCA) to IPM was examined histochemically in 2 month-old and 1.5 year-old rats under light- and dark-adapted conditions. Two month-old animals showed obvious light-evoked changes in the rod associated IPM: the photoreceptor inner segment zone showed a greater fluorescence than the outer segment zone in the light, whereas the staining-intensity of the former was less than that of the latter in the dark. On the other hand, 1.5 year-old rats did not show such light-evoked IPM responses as in 2 month-old animals: no light-dark differences were found in RCA-1 binding. The scarce, linear, preferential binding of RCA-1 to the cone-associated IPM was the same in both lighting conditions independent of the age.

[Detection of dual phase of light response of interphotoreceptor matrix]

The postnatal development of light-evoked changes in the interphotoreceptor matrix (IPM), a complex of the extracellular matrix that surrounds the photoreceptors and lies between them and the retinal pigment epithelium, was studied by use of a histochemical probe colloidal iron in rats at various postnatal days of age. In the dark, IPM constituents distributed uniformly throughout the outer segment zone and in the apical region of the inner segment zone; this dark pattern of IPM distribution was commonly observed in animals ranging from postnatal day 12 to one year. In the light, little changes were observed at postnatal day 12, followed by varying light-evoked changes in the IPM with increasing ages. At postnatal day 14, the IPM constituents showed a distribution towards the basal region of the inner segment zone along with the dark pattern. At postnatal day 16, they concentrated in bands at the apical and basal region of the outer segment zone, and also in the inner segment zone with expansion from the apical to basal region with increasing time after light exposure. At age one year, the light-adapted IPM constituents were distributed in a manner similar to that on postnatal day 14. The present results confirm the light-evoked changes in the IPM as revealed by colloidal iron-recognized IPM components and provide evidence for postnatal development of the light-evoked changes in the IPM components, whereby the changes appeared earlier and were preserved longer in the basal region of the inner segment.

Development of light-evoked changes of the interphotoreceptor matrix in normal and RCS rats with inherited retinal dystrophy

The interphotoreceptor matrix (IPM) has recently been shown to undergo a change in distribution following the transition between light and dark [IPM light response: Uehara et al., (1990 b) Science 248, 1633-36]. In the present study, the development of light-evoked IPM changes has been examined histochemically in the retinas of normal and Royal College of Surgeons (RCS) rats with inherited retinal dystrophy between the ages of post-natal day (P) 12 and 40. In normal rats at P12 and P14, the IPM was uniformly and intensely stained with the colloidal iron reaction in both light- and dark-adapted retinas. The capacity of the IPM to undergo the light-evoked distributional change shown previously in adults appeared between P14 and P16. At P16 and older ages, the IPM in light-adapted rats was concentrated in bands at the apical and basal regions of the outer segment zone, whereas the IPM remained uniformly stained in dark-adapted rats. In RCS rats, the light-evoked change developed at the same age as in normal rats, although it was lost between P20 and P25. Correlations of the time of onset and loss (in RCS rats only) of the light-evoked IPM distributional change with other developmental events suggest that mature, organized photoreceptor outer segments are necessary for the IPM light response to occur, and that in RCS rats the disruption of the IPM light response may contribute to the characteristic accumulation of IPM in the basal outer segment zone and photoreceptor cell death in this form of retinal degeneration.

[Classification of light-evoked distribution of interphotoreceptor matrix]

Distributional patterns of the interphotoreceptor matrix (IPM) under several different light conditions were examined in adult rats using colloidal iron staining. In the dark, the IPM distributed uniformly throughout photoreceptor outer segments including apical halves of inner segments. After exposure to light for 1 min, the colloidal iron-bound IPM concentrated in bands at apical and basal regions of outer segments and at apical inner segments. After exposure to light for 5-30 min, the IPM distributed throughout inner segments, in addition to the distribution at apical and basal outer segments. In excessive light, diffuse IPM staining was observed throughout the photoreceptor layer. These findings suggest that the light response of the IPM around outer segments precedes that around basal inner segments. It is also remarkable that the excessive light-induced distributional pattern of the IPM is similar to patterns in inherited retinal dystrophy and light-induced retinal degenerations.

[Lectin binding in the interphotoreceptor matrix in neuraminidase-induced retinal detachment]

Binding sites of fluorescence isocyanate-labeled lectins, peanut agglutinin (PNA) and Ricinus communis agglutinin-1 (RCA-1), were studied in the interphotoreceptor matrix (IPM) of adult rat retinas that were pretreated with an intravitreous injection of neuroaminidase. The localization of binding sites to the subretinal IPM differed significantly between the two lectins. PNA bound to the subretinal IPM components in a cord-like fashion that formed a bridge between the apical photoreceptor outer segments and the surface of the RPE. On the other hand, RCA-1 showed homogeneously prominent binding to the subretinal space IPM, the intensity of which appeared to inversely correlate with the extent of neuraminidase-induced retinal separation. The results suggest that the IPM may consist of mucin-type glycoconjugates as recognized by PNA and serum-type ones as bound by RCA-1, and that these IPM components may play different roles in the maintenance and organization of photoreceptor-RPE complex, e.g. the mucin-type for the retinal adhesion and the serum-type for the transport of metabolites.

Rod- and cone-associated interphotoreceptor matrix in the rat retina. Differences in light-evoked distributional changes

Several of the components of the interphotoreceptor matrix (IPM) in the rat have recently been shown to undergo a light-evoked shift in distribution or molecular conformation. In the light, the IPM appears concentrated at the apical surface of the retinal pigment epithelium (RPE) and in the basal outer segment region at the inner and outer segment junction, with relatively little present in the intervening interstitial zone adjacent to the outer segments. By contrast, the IPM in the dark is distributed almost uniformly across the outer segment layer. In the present study, the authors explored whether specialized domains of IPM known as the cone matrix sheaths undergo light-induced changes similar to those previously shown for the IPM as a whole. Fluorescence lectin histochemistry was used on retinal sections of light- and dark-adapted rats with lectins that show selective or preferential binding to cone matrix sheaths, peanut agglutinin (PNA), and Ricinus communis agglutinin (RCA-1). Lectin binding to cone matrix sheaths was the same in both lighting conditions, unlike the rod-associated IPM. These experiments and others using pretreatment of sections with neuraminidase suggested different roles of RCA-1 and PNA-binding components of the IPM in different photoreceptor-RPE cell interactions, including the transfer of substances between the two cell types and retinal adhesion.

Lectin binding of the interphotoreceptor matrix during retinal development in normal and RCS rats

The retinas of both normal and Royal College of Surgeons (RCS) rats with inherited retinal dystrophy have been examined using lectin histochemistry to determine the developmental and degenerative changes of the glycoconjugates in the interphotoreceptor matrix (IPM) between postnatal day (P) 10 and P25, when the adult lectin binding patterns are seen in normal rats. Wheat germ agglutinin (WGA; recognizing sialic acid and/or N-acetyl-D-glucosamine) bound to the apical surface of the retinal pigment epithelium (RPE) sparsely at P10 and prominently at P12 in both strains. In both strains at P14, WGA also stained the basal outer segment zone at the inner segment-outer segment junction. Between P14 and P16 in both strains, there was a dramatic increase in the binding of the interstitial region, the space alongside the outer segments and between the apical and basal outer segment zones. The binding pattern of WGA in normal rats remained basically unchanged from P16 to P25, although the intensity of binding was increased somewhat. Ricinus communis agglutinin-1 (RCA-1; specific for galactosyl residues) bound to the outer segment zone prominently and diffusely with increasing intensity with age at P10, P12 and P14 in both strains. At P16 and older, the intense binding of the interstitial zone was dramatically reduced and the RCA-1 bound primarily to the inner and outer segment junctional region, with weak binding to the apical surface of the RPE in both strains. At P25, the binding of the inner and outer segment junctional region was even more restricted, limited to punctate sites in this zone in normal rats and almost missing in RCS rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Light-evoked changes in the interphotoreceptor matrix

The normal function of vertebrate photoreceptor cells depends on multiple interactions and transfer of substances between the photoreceptors and the retinal pigment epithelium (RPE), but the mechanisms of these interactions are poorly understood. Many are thought to be mediated by the interphotoreceptor matrix (IPM), a complex extracellular matrix that surrounds the photoreceptors and lies between them and the RPE. Histochemical, immunocytochemical, and lectin probes for several IPM constituents revealed that components of the IPM in the rat undergo a major shift in distribution or molecular conformation after the transition between light and dark. In the light, various IPM constituents concentrated in bands at the apical and basal regions of the outer segment zone; in the dark, they distributed much more uniformly throughout the zone. The change in IPM distribution was triggered by the light-dark transition; it was not a circadian event, and it was not driven by a systemic factor. The light-evoked change in IPM distribution may facilitate the transfer of substances between the photoreceptors and the RPE.

Distribution of glycosyltransferase in bovine eyes

The activities of sialyl-, fucosyl- and galactosyltransferase were measured in membrane preparations from bovine eyes. Radioactive sugars from CMP-N-neuraminic acid, GDP-fucose and UDP-galactose were incorporated into the endogenous and exogenous acceptors. The enzymatic activities of all three glycosyltransferases were found to be high in the neural retina and retinal pigment epithelium, moderate in the cornea and uvea, and low in the lens and sclera, except for a high galactosyltransferase activity in the cornea.

Lectin-cytochemical study on epithelial mucus glycoprotein of conjunctiva and pterygium

The epithelium of pterygium and conjunctiva was studied with reference to cytochemical reactivity to six fluorescein-labeled lectins that recognize a certain carbohydrate residue(s) of cellular membrane-bound or secretory glycoprotein: Ulex europaeus agglutinin-1 (UEA-1, specific for fucose); Dolichos biflorus agglutinin (DBA, specific for N-acetylgalactosamine); peanut agglutinin (PNA, specific for galactose-beta 1-3N-acetylgalactosamine): wheat germ agglutinin (WGA, specific for N-acetylglucosamine and N-acetylneuraminic acid); Concanavalia ensiformis (Con A, specific for mannose); Ricinus communis agglutinin-1 (RCA-1, specific for galactose). Non-goblet epithelial cells of pterygium were labeled with UEA-1, DBA and PNA, while those of conjunctiva were not. Distribution density of goblet cells was larger in pterygium than in conjunctiva, but there was no distinct difference in lectin reactivity between the two tissues, with marked label with WGA, PNA and RCA-1. Con A did not bind to either pterygium or conjunctiva. The observations suggest the presence of anomalous mucus glycoproteins secreted from pterygium.

Specific binding of peanut agglutinin to foveal and peripheral cone photoreceptors of monkey retina

peanut agglutinin, a lectin with specific affinity for galactose beta-(1----3)-N-acetyl-galactosamine disaccharides, showed binding to the slender cones in the rod-free fovea as well as to the conical cones in the periphery of the monkey (Macaca fuscata) retina, but not to the rods, as revealed by light-microscopic cytochemistry with horseradish-peroxidase-conjugated lectin.

Specialization of the interphotoreceptor matrices around cone and rod photoreceptor cells in the monkey retina, as revealed by lectin cytochemistry

The binding sites of two lectins, peanut agglutinin (PNA) and wheat germ agglutinin (WGA), in the interphotoreceptor matrix (IPM) and photoreceptor plasma membranes of the Japanese monkey (Macaca fuscata) retina were localized using a pre-embedding staining method with ferritin-conjugated (Fer) lectins as well as a postembedding staining method with fluorescence-labeled (FITC) lectins. FITC-PNA, but not WGA, stained cylindrical domains of the IPM around cone outer and inner segments, while the IPM around rods stained with FITC-WGA but not PNA. When the intact (not detached) retinal tissues were incubated with Fer-lectin, the lectin generally labeled neither the IPM nor photoreceptor plasma membranes, but labeled only those structures in detached portions occurring at the edges of occasional retinal tissue blocks. Thus, the neural retinas physically isolated from the retinal pigment epithelium (RPE) were utilized principally here. Ultrastructurally, the IPM in the intact retina consisted of granular and filamentous materials; the IPM in the isolated neutral retina also retained those components, although somewhat loosely organized, and the IPM around cones appeared to be preserved better than did the IPM around rods. Fer-PNA bound to the IPM associated with cones, but not rods; Fer-WGA bound to the rod- but not cone-associated IPM. The ferritin particles were found to lie close to the granular and filamentous materials. Those photoreceptor-associated IPMs extended to the apical surface of the RPE in detached portions or to the apical villi of the RPE which were frequently found in the isolated neural retinas. Also, Fer-PNA labeled the cone, but not rod, plasma membranes; Fer-WGA bound heavily to the plasma membranes of rod and cone outer segments, but sparsely to those of their inner segments. These results suggest that the IPM comprises chemically and physically differential domains specialized for cone and rod photoreceptor cells, and that these specialized IPM are structurally so stable that may be involved in isolating photoreceptor cells physicochemically from each other and in the interactions between the photoreceptors and the RPE, such as retinal adhesion.