PURPOSE To determine the effects of human retinal pigment epithelial (RPE) cell pigment granules on photosensitized and iron ion-mediated oxidation and the effect of the photodegradation of melanosomes on their antioxidant properties. METHODS RPE cells were isolated from human and bovine eyes; pigmented and nonpigmented bovine retinal pigment epithelia were isolated separately. Melanosomes, m...

The pineal hormone, melatonin (5-methoxy N-acetyltryptamine) induces a rapid aggregation of melanin-containing pigment granules in isolated melanophores of Xenopus laevis. Treatment of melanophores with activators of protein kinase C (PKC), including phorbol esters, mezerein and a synthetic diacylglycerol, did not affect pigment granule distribution but did prevent and reverse melatonin-induced...

The pineal hormone, melatonin (5-methoxy N-acetyltryptamine) induces a rapid aggregation of melanin-containing pigment granules in isolated melanophores of Xenopus laevis. Treatment of melanophores with activators of protein kinase C (PKC), including phorbol esters, mezerein and a synthetic diacylglycerol, did not affect pigment granule distribution but did prevent and reverse melatonin-induced...

Neuromelanin is a complex polymer pigment found primarily in the dopaminergic neurons of human substantia nigra. Neuromelanin pigment is stored in granules including a protein matrix and lipid droplets. Neuromelanin granules are yet only partially characterised regarding their structure and function. To clarify the exact function of neuromelanin granules in humans, their enrichment and in-depth...

Microtubule (MT)-based organelle transport is driven by MT motor proteins that move cargoes toward MT minus-ends clustered in the cell center (dyneins) or plus-ends extended to the periphery (kinesins). Cells are able to rapidly switch the direction of transport in response to external cues, but the signaling events that control switching remain poorly understood. Here, we examined the signalin...

Microtubule (MT)-based organelle transport is driven by MT motor proteins that move cargoes towards MT minus-ends clustered in the cell center (dyneins), or plus-ends extended to the periphery (kinesins). Cells are able to rapidly switch the direction of transport in response to external cues, but the signaling events that control switching remain poorly understood. Here, we examined the signal...

In the teleost eye, the melanin granules of the retinal pigment epithelium (RPE) move in response to changes in light conditions. In the dark, pigment granules aggregate toward the cell base, and in the light, they disperse into long apical projections. Isolated RPE cells from the green sunfish (Lepomis cyanellus) were used to investigate the mechanism and regulation of pigment movement. Changi...

The properties of the amoebocytes and intestinal epithelium of Venus mercenaria were studied by a variety of cytochemical procedures designed to demonstrate proteins, enzymes, carbohydrates, and lipids. The cytoplasm of the amoebocytes contains specific granules which are constantly present and which are interpreted as being atypical mitochondria. Identification of their mitochondrial nature re...

When microtubules in teleost melanophores are disrupted with antimitotic agents, colchicine, high hydrostatic pressure, low temperature, and vinblastine, the alignment and movement of the pigment granules in these cells disappear; during recovery, the return of alignment and movement corresponds in both time and space with the repolymerization of microtubules. Furthermore, analysis of nearest n...

The presence of pigment granules in the anterior vitreous, in the absence of previous ocular surgery, is almost pathognomonic of a retinal break (Shafer, I 965). To investigate the accuracy of this observation, a consecutive series of patients with retinal holes were examined. Method All patients presenting to us over an i8-month period at Moorfields Eye Hospital with rhegmatogenous retinal det...