Sperm RNA as a Mediator of Genomic Plasticity

Figure 2

RNA in sperm. Sperm RNA is associated with the nuclear scaffold visualised here in a decondensed human spermatozoon nucleus (a) stained with RiboGreen. Compared with typical spermatids (b), where 28S and 18S rRNA dominate the cytoplasmic RNA profile, seen here on a Bioanalyzer trace (Agilent Technologies), sperm appear to be dominated by smaller RNAs which are essentially free of intact 28S and 18S rRNA (c). The absence of these large subunit rRNAs has been used as a benchmark for purification of sperm to homogeneity. However one report suggests that although 28S RNA may indeed be depleted in sperm, ribosomes are present and the 18S RNA subunit can be detected if the background level of DNA contamination is reduced (d). The influence of round cell contamination in sperm preparations is shown in (e) for the individual sample 28S rRNA peaks shown in (d); boxed. As the level of round cell contamination drops (wedge), the quantity of 28S RNA as indicated by the peak shading in (e) falls correspondingly, adapted with permission from Lalancette et al, 2008 (a); Gilbert et al, 2007 (b) and (c); and Cappallo-Obermann et al, 2011 (d) and (e). M indicates Marker.

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