Distribution of tubulin, kinesin, and dynein in light- and dark-adapted octopus retinas

Abstract

Cephalopod retinas exhibit several responses to light and dark adaptation, including rhabdom size changes, photopigment movements, and pigment granule migration. Light- and dark-directed rearrangements of microfilament and microtubule cytoskeletal transport pathways could drive these changes. Recently, we localized actin-binding proteins in light-/dark-adapted octopus rhabdoms and suggested that actin cytoskeletal rearrangements bring about the formation and degradation of rhabdomere microvilli subsets. To determine if the microtubule cytoskeleton and associated motor proteins control the other light/dark changes, we used immunoblotting and immunocytochemical procedures to map the distribution of tubulin, kinesin, and dynein in dorsal and ventral halves of light- and dark-adapted octopus retinas. Immunoblots detected alpha- and beta-tubulin, dynein intermediate chain, and kinesin heavy chain in extracts of whole retinas. Epifluorescence and confocal microscopy showed that the tubulin proteins were distributed throughout the retina with more immunoreactivity in retinas exposed to light. Kinesin localization was heavy in the pigment layer of light- and dark-adapted ventral retinas but was less prominent in the dorsal region. Dynein distribution also varied in dorsal and ventral retinas with more immunoreactivity in light- and dark-adapted ventral retinas and confocal microscopy emphasized the granular nature of this labeling. We suggest that light may regulate the distribution of microtubule cytoskeletal proteins in the octopus retina and that position, dorsal versus ventral, also influences the distribution of motor proteins. The microtubule cytoskeleton is most likely involved in pigment granule migration in the light and dark and with the movement of transport vesicles from the photoreceptor inner segments to the rhabdoms.

Expression and light-dependent translocation of β-arrestin in the visual system of the terrestrial slug Limax valentianus

“…6A-E,S), which is reportedly enriched in the apical projection of the rhabdomere (Fig. 1B; Kataoka, 1975;Martinez et al, 2000). Similarly, the dot-like distribution of β-arrestin was almost equivalent to that of α-tubulin in a section crossing the apical projection of the rhabdomere (Fig.…”

Co‐expression of opsins in the eye photoreceptor cells of the terrestrial slug Limax valentianus

“…To further analyze the distribution of these opsins in the rhabdomere, each opsin was immunostained with the specific antibody in the thin serial sections of the retina, which was sectioned in a manner intersecting the apical projection of the photoreceptor cell (see Figure a,b). The anti‐α‐tubulin antibody was used to mark the apical projection (Figure a) of a photoreceptor cell in our previous study (Matsuo et al, ) because this structure is enriched with microtubules (Kataoka, ; Martinez et al, ). However, in the present study, Alexa594‐labeded streptavidin was used instead because streptavidin stained the apical projection more clearly than anti‐α‐tubulin for unknown reasons (Figure c).…”

Proteomics Studies on the three Larval Stages of Development and Metamorphosis of Babylonia areolata

“…Furthermore, dynein may regulate the proliferation and cycle of nerve cells, thereby promoting development of the nervous system 37 . There have been studies on distribution in the optic nerve system of molluscs 38 , the left and right spiral formations 39 , and reproductive development 28 . Spectrin, a cytoskeletal protein, may maintain the stability of membrane and its shape and participate in a variety of MFs 40 , and may also interact with actin to establish a membrane network that maintains the elasticity of the cell 41 .…”