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Updated: Mar 20, 2026
Cytological Analysis of Spermatogenesis: Live and Fixed Preparations of Drosophila Testes
Published on: January 20, 2014
A conditional Orco requirement in the somatic cyst cells for maintaining spermatids in a tight bundle in Drosophila
Pankaj Dubey1, Prakash Joti, Krishanu Ray
1Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai 400 005, India.
Abstract:
Odorant receptors (OR) heterodimerizes with the OR co-receptor (Orco), forming specific odorant-gated cation channels, which are key to odor reception at the olfactory sensory neurons (OSN). Mammalian ORs are expressed in many other tissues, including testis. However, their biological implications are yet to be fully ascertained. In the mosquito, Orco is localized along the sperm tail and is indicated to maintain fidelity. Here, we show that orco expresses in Drosophila testis. The levels are higher in the somatic cyst cells. The orco-null mutants are perfectly fertile at 25 degree C. At 28 degree C, the coiled spermatid bundles are severely disrupted. The loss of Orco also disrupts the actin cap, which forms inside the head cyst cell at the rostral ends of the spermatid nuclei after coiling, and plays a key role in preventing the abnormal release of spermatids from the cyst enclosure. Both the defects are rescued by the somatic cyst cell-specific expression of the UAS-orco transgene. These results highlight a novel role of Orco in the somatic tissue during sperm release.
Insights
The odorant receptor co-receptor (Orco) plays a crucial role in Drosophila sperm development. Loss of Orco in somatic cyst cells disrupts sperm bundle integrity and actin cap formation, impacting fertility.
Area of Science:
- Reproductive biology
- Molecular genetics
- Insect physiology
Background:
- Odorant receptors (OR) and their co-receptor (Orco) form cation channels essential for olfaction.
- While ORs are found in mammalian testes, their function there is unclear.
- Orco has been implicated in sperm tail function and maintaining fidelity in mosquitoes.
Purpose of the Study:
- To investigate the expression and function of Orco in Drosophila testis.
- To determine Orco's role in male fertility and sperm development.
Main Methods:
- Analysis of orco expression patterns in Drosophila testis.
- Generation and phenotypic analysis of orco-null mutants at different temperatures.
- Assessment of spermatid bundle morphology and actin cap formation.
- Rescue experiments using somatic cyst cell-specific Orco expression.
Main Results:
- Orco is expressed in Drosophila testis, with higher levels in somatic cyst cells.
- orco-null mutants exhibit normal fertility at 25°C but show severe disruption of coiled spermatid bundles at 28°C.
- Loss of Orco disrupts the actin cap formation crucial for preventing premature spermatid release.
- Somatic cyst cell-specific Orco expression rescues these fertility defects.
Conclusions:
- Orco has a novel, essential function in somatic cyst cells during sperm development and release in Drosophila.
- Orco's role extends beyond olfaction to regulating male reproductive processes.
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