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At least 19 recordsLinked to original sources
PubMed1976

Isolation of retina-specific cell-aggregating factor from membranes of embryonic neural retina tissue.

There is increasing evidence that developmental associations among embryonic cells are mediated by specific components of the cell surface. Earlier work has indicated that such components are extruded into the medium of primary monolayer cultures of embryonic cells, and that they represent the active constituents of the tissue-spedific cell-aggregating factors isolated fro- the supernatant medium of such cultures. We presently report that tissue-specific cell-aggregating factors can be obtained directly from embryonic tissues, and describe the isolation and partial purification of retina-spedific factor from a cell-membrane preparation derived from retina tissue of the chick embryo. Extraction of the purified membrane preparation with 1-butanol yielded an activity in the aqueous phase which resides in a protein probably a glycoprotein, with an estimated molecular weight of 50,000 in solution. This material could be obtained from retinas of embryos not older than 13 days, and only pre-13-day cells responded to its cell-aggregating activity. By these characteristics, this membrane-derived retina factor closely resembles the retina cell-aggregating glycoprotein previously purified from the supernatant medium of retina cell cultures. It is of special interest that the cell-aggregating protein is obtainable from cellular membranes during those stages of development when retina cells are most actively engaged in histological organization. Work in progress indicates that, by the procedures described herein, tissue-specific cell-aggregating factors can also be obtained from membrane preparations of other embryonic tissues.

Age Factors↗
PubMed1976

[Changes of the phosphatides and their fatty acids in the retina and in the fasciculus opticus after retinal detachment: investigations of human and animal retinae (author's transl)].

In this study the effect of an experimentally provoked retinal detachment on the pattern of the phosphatides and fatty acids of the retina and the optic nerve of adult rabbits was investigated. The analysis was performed one month, and 4 months after the operation, and the values were related to the findings in control animals of the same age, and of the age of one day and 30 days respectively. In this way changes in the total lipide, in the phosphatides and in their fatty acids could be revealed, with a tendency towards the developmental stage of the 20th up to the 30th day of life. Between retina and optic nerve no difference was found neither temporally nor regarding the quantitative reaction. In the detached human retinae the same reactions can be proved as in the animal experiment. The relationship of these findings to the recovery of the operatively reatached human retina is discussed.

Adult↗
PubMed1978

Studies on the retina and the pigment epithelium in hereditary canine ceroid lipofuscinosis, I. The distribution of enzymes in the whole retina and pigment epithelium.

The massive accumulation of autofluorescent lipopigments, representative of autoxidation, is a key morphological feature in canine ceroid lipofuscinosis (CCL). In the eye peroxidase, catalase, and four acid hydrolases were compared with regard to aged and clinical condition in a series of English setters affected with CCL. In unaffected English setters "soluble" peroxidase increased in the RPE to adult levels at 2 yr of age. Affected dogs had higher RPE peroxidase activity earlier in life, which then decline with age. The soluble retinal peroxidase of both unaffected and CCL dogs increased steadily with age, but the latter group of dogs were much lower in activity. By 2 yr of age, RPE and retinal peroxidase values were only 25% and 47% of unaffected dog levels. Although the soluble enzyme of unaffected dogs exhibited a maturational profile, membrane-bound RPE peroxidase showed a hyperbolic curve reaching a maximum at 10 mo of age. By 2 yr of age, the "bound" enzyme in affected dogs was below unaffected levels in the RPE and retina. Three acid hydrolases were slightly increased in the RPE and retina of affected dogs. Acid lipase activity, however, was similar in both unaffected and CCL dogs. Catalase was not found in the RPE of either group of dogs. The catalase activity in the retina of both affected and unaffected dogs was at similar levels. Since catalase is not present in the RPE, the major defense against peroxidase accumulation and peroxide toxicity probably depends upon peroxidase. The present study indicates that a decrease in this key regulating enzyme may be related to the formation of lipopigments in the retina and RPE of dogs with CCL.

Age Factors↗
PubMed1978

Biosynthesis of protein by the retina. The properties of a cell-free system obtained from rat retina.

We describe the properties of a post-mitochondrial (30,000 g) supernatant fluid obtained from rat retina which incorporated (3H) leucine into an alkali-stable acid-insoluble fraction (protein). It contained a substance, possibly leucine, which interfered with the incorporation of (3H) leucine into acid-insoluble fractions and which could be removed by passage through Sephadex G-25 or by dialysis. Magnesium was essential for protein synthesis and potassium enhanced it. Radioactive leucine was incorporated in the protein only when both adenosine triphosphate and guanosine triphosphate were present. Puromycin inhibited protein synthesis. The amount of material required for this assay is small. The system can be used to study changes in protein synthesis in the retinas of rats with retinal dystrophies.

Adenosine Triphosphate↗
PubMed1976

[Radioautographic study of melanin synthesis in cells of the pigmented epithelium of the retina in adult tritons following surgical removal of the retina].

The results are given for the autoradiographic study of melanin synthesis in the pigment epithelium cells of eye retina in the adult newts by the incorporation of 3H-dioxyphenylalanine (3H-DOPA). The synthesis of melanin began 4--8 days after the operation in the peripheral parts of the eye and but it was not observed in the central region of the eye fundus even 25 days alter the operation. A suggestion is put forward to the effect of the existence of different mechanisms for the initiation of melanin synthesis in these subpopulations of pigment epithelium.

Animals↗
PubMed1975

Choline acetyltransferase and acetylcholine esterase activities in normal and biologically fractionated mouse retinas.

Radiometric biochemical assays were carried out for choline acetyltransferase (ChAc) and acetylcholine esterase (AChE) in retinas isolated from 90-day-old pigmented mice. The retinas were either normal [(C57Bl (6) and rd/le controls)], or genetically receptorless (rd/le and C3H), or had markedly reduced inner layers due to postnatal treatment of C57Bl (6) mice with monosodium glutamate. The receptorless rd/le retinas were obtained from an inbred hybrid stock that provided littermate contols with normal retinas. Glutamate-damaged retinas were compared to retinas from untreated control animals. Receptorless C3H retinas were compared to both sources of normal retinas. Control retinas had specific activities (millimoles per kilogram dry weight per hour) of 36.5 to 38.5 for ChAc and 2,180 to 2,350 for AChE and total activities per retina (nanomoles per hour) of 23 to 26 for ChAc and 1,360 to 1,160 for AChE, with the higher total values coming from slightly heavier rd/le controls. Receptorless retinas had 44 to 48 times the ChAc specific activity of those from glutamate-treated animals and had 2.4 to 2.5 times that of retinas from control animals. They had five to six times the AChE specific activity of retinas of glutamate-treated animals and 2.4 to 2.5 times that of controls. On a total activity per retina basis, receptorless rd/le retinas had 81 per cent of the ChAc activity and 66 per cent of the AChE activity of those from littermate controls and receptorless C3H retinas had 97 per cent and 98 per cent of the total ChAc and AChE activity of the C57Bl (6) controls, but only 91 per cent and 82 per cent of the same total activities in the heavier rd/le controls. The data are consistent with the view that both enzymes are normally more concentrated in the inner than outer retina, with the disparity being more marked for ChAc.

Acetylcholinesterase↗
PubMed1979

Autoradiographic identification of acetylcholine in the rabbit retina.

Rabbit retinas were studied in vitro under conditions known to maintain their physiological function. Retinas incubated in the presence of [3H]choline synthesized substantial amounts of both [3H]phosphorylcholine and [3H]acetylcholine. With time, [3H]phosphorylcholine proceeded into phospholipids, primarily phosphatidylcholine. Retinas pulse-labeled by a 15-min exposure to 0.3 microM [3H]choline were incubated for a subsequent hour under chase conditions designed either to retain newly synthesized acetylcholine within synapses or to promote its release. At the end of this time the two groups of retinas were found to contain equal amounts of radioactivity in the phospholipid pathway, but only the retinas incubated under the acetylcholine-protecting conditions contained [3H]acetylcholine. Freeze-dried, vacuum-embedded tissue from each retina was autoradiographed on dry emulsion. All retinas showed silver grains over the photoreceptor cells and faint labeling of all ganglion cells. In the retinas that contained [3H]acetylcholine, silver grains also accumulated densely over a few cells with the position of amacrine cells, over a subset of the cells of the ganglion cell layer, and in two bands over the inner plexiform layer. Fixation of the retina with aqueous osmium tetroxide retained only the radioactive compounds located in the photoreceptor and ganglion cells. Sections from freeze-dried tissue lost their water-soluble choline metabolites when exposed to water, and autoradiography of such sections again revealed radioactivity primarily in the photoreceptor and ganglion cells. Radioactive compounds extracted from the sections were found to faithfully reflect those present in the tissue before processing; analysis of the compounds eluted from sections microdissected along the outer plexiform layer showed [3H]acetylcholine to have been synthesized only by cells of the inner retina. Taken together, these results indicate that the photoreceptor and ganglion cells are distinguished by a rapid synthesis of choline-containing phospholipids, while acetylcholine synthesis is restricted to a few cells at both margins of the inner plexiform layer. They imply that the only neurons to release acetylcholine within the rabbit retina are a small group of probable amacrine cells.

Acetylcholine↗
PubMed1975

Immunochemical analysis of water-soluble antigens of chick retina in the course of embryogenesis.

Water-soluble antigens of chick retina were investigated using rabbit antisera to total extract and to individual electrophoretic fractions of retinal extract by methods of immunoelectrophoresis and Ouchterlony precipitation test. In the retina of the adult chick six serum and eleven tissue antigens were demonstrated. The tissue antigens of the retina comprised one organ-specific antigen and ten inter-organ antigens which were characterized by nonuniform distribution in tissues and organs of adult chick. Three antigens out of these were found only in tissues of the eye (retina, iris) and in the brain--inter-organ antigens of 'narrow' specificity. The ohter seven inter-organ antigens were found in tissues of brain and eye, as well as in various tissues and organs of hens--inter-organ antigens of 'broad' specificity. A high degree of antigen similarity between retina and iris was observed. Anti-retina sera in chick lens could detect only inter-organ antigens of 'broad' specificity. In the course of embryogenesis the first to appear in the developing retina were inter-organ antigens of 'broad' specificity (on 3rd day of incubation). Formation of antigens of this group was completed by the 9th day of incubation. On the contrary, inter-organ antigens of 'narrow' specificity appeared later, in the period of histogenesis of retina (from 5 to 18 days of incubation). The organ-specific antigen of retina was found by 7th day of incubation. One of the inter-organ retinal antigens of'narrow' specificity (retina-iris-brain) appeared in the developing chick brain at the same time as in retina--on 10th-11th day of incubation. Using the indirect immunofluorescence antibody technique this antigen was identified in the cytoplasm of retinal cells and brain neurones, but was not detected in the nerve fibres.

Animals↗
PubMed1979

Postnatal neurogenesis in the kitten retina.

Postnatal neurogenesis in the kitten retina was studied using 3H-thymidine radioautography. Kittens were injected with 3H-thymidine at 1 day, 10 days, 3 weeks or 4 weeks after birth and allowed to survive until 14 weeks of age. Labeled neuronal nuclei were not found in the ganglion cell layer in any of the retinas, but they were seen in the other nuclear layers of the same retinas. In retinas from kittens injected at one day after birth, the peripheral 80% of the length of the retina (in sections cut parallel to the dorsoventral meridian) contained labeled nuclei; the central 20%, around the optic disc, contained no labeled nuclei. Near the ora serrata most nuclei in both inner and outer nuclear layers were labeled. Away from the ora serrata the proportion of labeled to unlabeled nuclei gradually decreased. Labeled nuclei extended farther centrally in the the inner than the outer nuclear layer. The same pattern of labeling was repeated in retinas from kittens injected at ten days after birth, but fewer nuclei were labeled, and the central, unlabeled region around the optic disc was longer--55% of the length of the retina. Only a few nuclei near the ora serrata were labeled in retinas from kittens injected at three weeks after birth, and no labeled neurons were found in kittens injected at four weeks. From these results we conclude that all of the ganglion cells in the kitten retina are present by one day after birth, as are all of the other neurons in the central retina. In peripheral regions of the inner and outer nuclear layers, proliferation of cells destined to become neurons continues up to three weeks after birth.

Animals↗
PubMed1979

Topographic organization of the projections of the retina to the pretectal region in the rat.

The pattern of projection of the retina to the pretectal region and its retinotopic organization were investigated in the rat by autoradiographic and silver impregnation techniques for axonal pathways. The endings of retinal axons form three terminal fields in the pretectum in: 1, olivary pretectal nucleus (PO), bilaterally; 2, posterior pretectal nucleus (PP), bilaterally; and 3, nucleus of the optic tract (NTO), contralaterally. The following retinotopic pattern was observed in rats surviving peripheral retinal lesions and injections of 3H-proline in the same eye, when the positions occupied by terminal degeneration in Fink-Heimer stained sections were matched with the corresponding areas deficient in radiolabel in adjacent autoradiographic sections showing the surviving parts of the terminal fields. The nasal periphery of the retina maps along the adjoining edges of PO and PP, both of which extend obliquely, in a posterolateral direction, through the entire extent of the pretectum. Both nuclei map the line of representation of the anterior midline (in the temporal retina) along their opposite edges (anterolaterally, in PO; posteromedially, in PP). This mirror-image symmetry is completed by the representation of the ventral peripheral retina separately in the rostral poles and the dorsal peripheral retina separately in the caudal poles of both nuclei. The map in NTO is vertically oriented, with the temporal retina, dorsally, the nasal retina, ventrally, the ventral retina, rostrally, and the dorsal retina caudally represented. The binocular area of the terminal field in PO is subdivided by a terminal-free zone into two parts that may process separately events in the central and lateral visual field.

Animals↗
PubMed1979

Solubilization of frog brain and retina cholinesterase and studies of different molecular forms.

1. The cholinesterase (ChE) of frog brain and retina could be easily solubilized. About 10% of the brain and 20% of the retina ChE were found to be soluble in 0.05 M phosphate buffer. After treatment with 0.5% (v/v) Triton X-100, about 30% of the total ChE activity of the brain and only 10% for retina was left particle bound. NaCl by itself did not solubilize ChE. Use of higher NaCl concentrations in combination with Triton X-100 as well as higher detergent concentrations alone seemed to cause an inhibiting effect of the solubilized ChE from retina. 2. The solubilized ChE from brain as well as retina were electrofocused as one main activity peak, corresponding to isoelectric points of pH 6.1 and 6.0, respectively. A second molecular form at pH 5.9 was distinguishable for the brain, but not for retina ChE. 3. Sucrose gradient centrifugation indicated that the ChE solubilized from the brain and retina consists of two molecular forms exhibiting S values of 5.1 +/- 0.24, 10.9 +/- 0.33 and 6.1 +/- 0.30, 10.9 +/- 0.43, respectively. After solubilization by higher Triton X-100 concentrations the soluble extracts from brain and retina seemed to contain the activity of these forms in different proportions. 4. Polyacrylamide gel electrophoresis separated three molecular forms of the brain ChE. One of these forms was found to have a molecular weight of 394,000 +/- 20,000. The others were found to have an identical molecular weight of 550,000 +/- 10,000. Two molecular forms exhibiting molecular weights of 292,000 +/- 10,000 and 470,000 +/- 10,000, could be separated for retina.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗