Highly dynamic temporal changes of TSPY gene copy number in aging bulls.

The Y-chromosomal TSPY gene is one of the highest copy number mammalian protein coding gene and represents a unique biological model to study various aspects of genomic copy number variations. This study investigated the age-related copy number variability of the bovine TSPY gene, a new and unstudied aspect of the biology of TSPY that has been shown to vary among cattle breeds, individual bulls and somatic tissues. The subjects of this prospective 30-month long study were 25 Holstein bulls, sampled every six months. Real-time quantitative PCR was used to determine the relative TSPY copy number (rTSPY CN) and telomere length in the DNA samples extracted from blood. Twenty bulls showed an altered rTSPY CN after 30 months, although only 9 bulls showed a significant change (4 significant increase while 5 significant decrease, P<0.01). The sequential sampling provided the flow of rTSPY CN over six observations in 30 months and wide-spread variation of rTSPY CN was detected. Although a clear trend of the direction of change was not identifiable, the highly dynamic changes of individual rTSPY CN in aging bulls were observed here for the first time. In summary we have observed a highly variable rTSPY CN in bulls over a short period of time. Our results suggest the importance of further long term studies of the dynamics of rTSPY CN variablility

Pie chart representation of change in TSPY copy number in the 25 bulls over a period of 30 months relative to 0-month samples.

<p>P≤0.01.</p

Relative TSPY copy number change over the 30 months sampling period (rTSPY CN at T30—rTSPY CN at T0) in each individual bull.

<p>Relative TSPY copy number change over the 30 months sampling period (rTSPY CN at T30—rTSPY CN at T0) in each individual bull.</p

rTSPY CN measured by qPCR at every six months (T0-T30) during the 30 months experiment.

<p>The rTSPY CN is calculated against T0 (thus CN = 1). A line diagram representing all 15 bulls, The size of the circles at each time points are proportional to rTSPY CN±SEM.</p