Changes in volume of the rhabdom in the compound eye of Aedes aegypti L.

Abstract

The volume of the rhabdom in compound eyes of mosquitoes decreases upon illumination. This decrease is probably mediated by a bleaching of the visual pigment, since blue light is most effective in producing the change and red light is least effective. The reduction in rhabdom volume appears to be a result of rhabdomal membrane loss to coated vesicles and multivesicular bodies. These organelles were seen most frequently in blue adapted eyes, markedly less frequently in red adapted eyes, and only rarely in dark adapted eyes.

Light-/dark-induced changes in rhabdom structure in the retina of Octopus bimaculoides

“…This observation agreed with numerous reports on arthropods that demonstrated a cyclic breakdown and assembly of rhabdomere membranes (microvilli) in synchrony with the light/dark cycle (Eguchi and Waterman 1967;Meyer Rochow 1974;White and Lord 1975;Brammer and Clarin 1976;Nässel and Waterman 1979;Williams 1982a, b, c;Stowe 1980;1981;Blest 1978;Chamberlain and Barlow 1979;Herman 1991). In most instances, breakdown of the photoreceptive membrane began at dawn and new membrane was synthesized just after dusk.…”

“…Cephalopod photoreceptors contain two photopigments ± rhodopsin, localized primarily in the rhabdomeres, and retinochrome, concentrated in the myeloid bodies (Hara and Hara 1965, 1968, 1976Fukushima et al 1980;Robles et al 1987). Hara and Hara (1991) proposed that these two photopigments regenerate each other in the rhodopsin-retinochrome system.…”

Changes in the structure and pigmentation of the eyes of honeybee (Apis mellifera L.) queens with the "limão" mutation

“…Transmission electron microscopy of the compound eyes of individuals heterozygous (Ch/ch li ) and homozygous (ch li /ch li ) for the gene "limão" showed differences in the organization of the ommatidium and in the general pigmentation of the eye, which were similar to those of other bee eye mutants (Cruz-Landim et al, 1979, 1980aBrammer and Clarin, 1976).…”

“…The membranous structures containing pigment granules and an electron-dense ground material appeared to be of a lysosomal nature. These structures were present in the retinular cells of all mutants examined (Figure 2B) and corresponded to the multivesicular bodies responsible for the reduction in rhabdom volume in the presence of light (Brammer and Clarin, 1976). Since mutant eyes have less pigment in the pigmentary and retinular cells, the increase in incident light at the rhabdom could lead to a reduction in the number of rhabdomere microvilli as a mechanism of adaptation to brightness.…”

“…The shape of the rhabdom is correlated with the way in which incoming light excites the receptors. Thus, in mosquito eyes, the rhabdom volume decreases upon illumination, a response which is probably mediated by a bleaching of the visual pigment, since blue light is most effective in producing this change whereas red light is least effective (Brammer and Clarin, 1976). The reduction in rhabdom volume apparently results from a loss of membrane to multivesicular bodies and coated vesicles.…”