The effect of chloroquine in combination with bright light on the ultrastructure of crayfish (Orconectes limosus R.) photoreceptors was investigated in vivo. Chloroquine had several effects upon the crayfish retina. Multivesicular bodies (MVB) that are involved in lysosomal degradation of photosensory membrane were altered in ultrastructure. MVB frequently contained smaller MVB in a state of mo...

Using standard osmium fixation and methacrylate embedding techniques, a study has been made of the melanocyte of human biopsy skin removed under general and local anaesthesia. Melanogenesis was easily observable in the melanocytes, but immature pigment granules were rarely seen in the Malpighian cells. The passage of melanin from melanocyte to Malpighian cell-cytocrine secretion-is thought to h...

Necropsy material from the eye of a 23-year-old male known to have suffered from the Sjögren-Larsson syndrome, characterised by mental retardation, spastic diplegia or tetraplegia, congenital ichthyosis, and so-called glistening dots in the foveal and parafoveal areas of the fundus of the eye, was investigated ultrastructurally. The retinal pigment epithelium in the macular area showed a signif...

Three females in their fifties and five males in their seventies, all of whom had been exposed to the Nagasaki atomic bomb explosion in 1945, were investigated concerning the aging of neurons of the dorsal root ganglia. Through this study dealing with the frequency of neurons with intracytoplasmic pigments, lipofuscin, neuromelanin, eosinophilic granules and neurons free of pigment, no signific...

Polar arrays of microtubules play many important roles in the cell. Normally, such arrays are organized by a centrosome anchoring the minus ends of the microtubules, while the plus ends extend to the cell periphery. However, ensembles of molecular motors and microtubules also demonstrate the ability to self-organize into polar arrays. We use quantitative modeling to analyze the self-organizatio...

Streaming plasmodia of Physarum polycephalum were irradiated with a microscope-mounted ruby laser and the resulting changes were recorded by cinemicrography or streak photographs. Some lesions were processed for electron microscopy. By varying the incident energy, three levels of response were detected. Two transient responses, a gelation briefly blocking streams and a more severe gelation with...

Oocytes may remain in the ovary for months or years in a quiescent state from which they may be aroused within seconds by fertilization or activation. As a result of activation, the cortex of the sea urchin egg undergoes a radical reorganization that transforms it from a quiescent structure to one that undergoes rapid microvillar formation (2, 3) and membrane recycling (14). Initiation of this ...

. ABSTRACT Manganese (Mn) is postulated to play a role in wood decay caused by certain basidiomycetes. We determined the in vitro response of Heterobasidion annosum (Fr.) Bref. to Mn and compared differences between three isolates each of the S and the P intersterility groups from the Western United States. On manganese-amended malt agar plates, H. annosum produced a brownish-black pigment that...

Dermal specialized pigment cells (chromatophores) are thought to be one type of extraretinal photoreceptors responsible for a wide variety of sensory tasks, including adjusting body coloration. Unlike the well-studied image-forming function in retinal photoreceptors, direct evidence characterizing the mechanism of chromatophore photoresponses is less understood, particularly at the molecular an...