Allelic Expression of Drosophila Protamines during Spermatogenesis.

Rachelle L Kanippayoor,Amanda J Moehring

doi:10.1155/2012/947381

Rachelle L Kanippayoor, Amanda J Moehring

Open Access

https://doi.org/10.1155/2012/947381

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Abstract

In typical somatic cells, DNA is tightly organized by histones that are necessary for its proper packaging into the nucleus. In sexually-reproducing animals, the haploid product of male meiosis must be further condensed to fit within sperm heads, thus requiring an even greater degree of packaging. This is accomplished in most organisms by replacing histones with protamines, which allows DNA to be compacted into the reduced space. In mammals, protamines are produced after meiosis is complete and are transcribed by the single allele present in the haploid genome that is to be packaged into the sperm head. Here, we present our findings that protamine expression occurs from both alleles in diploid cells, rather than haploid cells, in two species of Drosophila. The differential allelic expression of protamines likely influences the selective pressures that shape their evolution.

Highlights

Spermatogenesis is a highly orchestrated process that, when operating properly, results in functional and motile sperm
Previous work on mammals found that protamines, used for packaging DNA into sperm heads, are expressed from the haploid genome after meiosis
It has been shown that protamines are expressed in the insect D. melanogaster, and are expressed in diploid cells prior to meiosis [11], it has not been shown whether this expression occurs from a single allele, as in mammals, or if both alleles are expressed

Summary

Introduction

Spermatogenesis is a highly orchestrated process that, when operating properly, results in functional and motile sperm. By crossing a male possessing the transgene of one fluorophore (e.g., RFP) with a female carrying the transgene of the other fluorophore (e.g., GFP) and examining the sperm fluorescence of the male offspring, referred to as a transgenic hybrid, we can elucidate when protamine gene expression occurs. Dual expression of RFP or GFP within one sperm head provides evidence of diploid gene expression from both alleles.

Results

Conclusion