Studies on the structure of ocellar photoreceptor cells of Drosophila melanogaster with special reference to subrhabdomeric cisternae

Abstract

We studied the structure of ocellar photoreceptor cells of Drosophila melanogaster, particularly the subrhabdomeric cisternae which our previous studies have shown to be essential structures for turnover of photoreceptive membranes in compound eyes. Each ocellus contained elongated photoreceptor cells with rhabdomeres positioned distally. In the subrhabdomeric regions, endocytotic invaginations were frequently observed, suggesting active turnover of photoreceptive membranes. In the vicinity of the photoreceptive microvilli, membranous structures similar to the subrhabdomeric cisternae in compound eyes were observed. These membranous structures were immunopositive for the rdgB protein, a phosphatidylinositol transfer protein that is localized to the subrhabdomeric cisternae in compound eyes. The ocellar photoreceptor cells of the retinal degeneration mutants (rdgA,B) were also studied. In these mutants, retinal degeneration has been reported to start, in compound eyes, with the disappearance of the subrhabdomeric cisternae. We found that the ocellar subrhabdomeric cisternae also disappear during the initial stage of retinal degeneration. From these observations, we conclude that the mechanism of photoreceptive membrane turnover in ocellar photoreceptor cells involves the rdgB and probably the rdgA proteins which are associated with subrhabdomeric cisternae, as is the case for photoreceptive membrane turnover in compound eyes.

Understanding the Structural and Developmental Aspect of Simple Eye of Drosophila: The Ocelli

“…The rhabdomeric microvilli is disintegrated and SRC is absent in the sub rhabdomere region confirming the conserved role of rdgB in both compound eye and ocelli. In both rdgA and rdgB mutants, SRC in ocelli disappeared in the same manner as compound eye hinting that these proteins have activity in ocelli [66].…”

“…The structural differences between compound eye and ocellus are summarised in Table 1. [66] and ommatidia from Wolff, T. and Ready, D. F. [87].…”

“…Ocelli development is a result of interplay among otd, wg and hh signalling pathways. This interplay results in the patterning from lateral to medial which results in frons, orbital cuticle and ocellar complex [4,66]. The wnt and Otx family members involved in anterior head patterning of both invertebrates and vertebrates [76] ( Figure 5).…”

Ultrastructural comparison of the ocelli of Sinopanorpa tincta and Bittacus planus (Mecoptera)

“…The detailed structure of dorsal ocelli is only documented in some insect groups (Goodman, 1970, 1981), including Ephemeroptera and Trichoptera (Hallberg and Hagberg, 1986), Odonata (Berry et al, 2007a; Chappell and Dowling, 1972), Orthoptera (Berry et al, 2007b; Goodman et al, 1979), Dictyoptera (Cooter, 1975; Weber and Renner, 1976), Hemiptera (Insausti and Lazzari, 2002), Hymenoptera (Toh and Kuwabara, 1974; Warrant et al, 2006), Lepidoptera (Dow and Eaton, 1976; Grünewald and Wunderer, 1996; Link, 1909), and Diptera (Yoon et al, 1996). However in Mecoptera, the fine structure of the ocelli has not been reported to date.…”

Evolution of Insect Eyes: Tales of Ancient Heritage, Deconstruction, Reconstruction, Remodeling, and Recycling

“…Second, a triplet of ocelli are embedded in the dorsal head cuticle ( Fig. 1) (Yoon et al 1996). These organs tend to be underfocused singlechamber eyes, projecting a blurry image that, at least in dragon flies, is thought to detect the horizon and assist in flight control (Stange et al 2002).…”