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Biogenesis and content of rhodopsin in the retina of the chick during development
J J Plantner1, B B Lentrichia, E L Kean
1Lorand V. Johnson Laboratory for Research in Ophthalmology, Department of Surgery, Case Western Reserve University, Cleveland, OH 44106.
Insights
Rhodopsin, a key visual pigment, begins forming early in chick development. Its concentration increases significantly before hatching, with biosynthesis potentially preceding outer segment development.
Area of Science:
- Ophthalmology
- Developmental Biology
- Biochemistry
Background:
- Rhodopsin is the primary visual pigment in rod photoreceptor cells.
- Understanding rhodopsin development is crucial for comprehending visual system maturation.
Purpose of the Study:
- To investigate the developmental timeline of rhodopsin formation in chick retinas.
- To compare spectral and radioimmunoassay methods for rhodopsin detection during development.
Main Methods:
- Spectral analysis of rhodopsin content in chick retinas at various developmental stages.
- Radioimmunoassay (RIA) for sensitive detection of rhodopsin from embryonic day 12 to adult.
- Quantification of rhodopsin concentration in retinas of developing, newly hatched, and adult chickens.
Main Results:
- Spectral methods detected rhodopsin at day 18, with levels increasing by hatching.
- Radioimmunoassay detected rhodopsin as early as embryonic day 12, with a rapid increase around day 17.
- Newly hatched chicks had significantly higher rhodopsin concentrations than 16-day-old embryos.
- Adult chicken retinas had half the rhodopsin concentration of 1-day-old chicks.
Conclusions:
- Rhodopsin biosynthesis begins much earlier than its spectral detection or outer segment formation.
- Developmental changes in rhodopsin levels are substantial during late embryogenesis and early post-hatching stages.
Abstract:
Developmental aspects of the formation of rhodopsin in the chick were investigated. The content of rhodopsin was measured in the retina of the developing chick embryo, newly hatched and adult chickens by both spectral and immunological procedures. Rhodopsin was first detected spectrally at day 18 (stage 43) with the level increasing about 6 fold through hatching. The concentration in the adult retina was about one half that present in the 1 day old chick. By the more sensitive procedure of radioimmunoassay (RIA), rhodopsin was detected as early as day 12 (stage 37), but was undetectable in the 8 day old embryo. The rhodopsin concentration remained low and relatively constant until day 17 (stage 42), at which point it increased rapidly up to hatching. Retina from the newly-hatched chick had a rhodopsin concentration some 30 fold higher than the 16 day old embryo (stage 41). The results of RIA indicate that the biosynthesis of rhodopsin may significantly precede the morphological appearance of outer segments.