sperm ubiquitination correlation with human semen quality

background: ubiquitin, an 8.5 kda peptide that marks other proteins for proteasomal degradation, tags defective sperm dur­ing epididymal passage. thus, sperm ubiquitination is a universal marker for sperm defects and can be used as a sperm func­tion test. the objective of the present study was to examine the relationships between sperm ubiquiti­nation and clinical se­men parameters, using simplified immunofluorescence assays in order to establish ubiq­uitin as a biomarker of male infertil­ity. methods: semen samples from 100 couples attending avicenna infertility clinic, tehran, iran, were collected and ana­lyzed ac­cording to who criteria. each sample was washed and adjusted at 10 6 sperm/ml concentration. sperm were coated on slides, using cytospin centrifugation and were fixed in buffered formaldehyde. subsequently ubiq­uiti­nated spermatozoa were evaluated by direct immunofluorescence microscopy using fitc-labeled anti-ubiq­uitin antibodies. after counting at least 200 sperm per sample, while employing light microscopy, the percentage of ubiq­uitinated spermatozoa was recorded on the same fields through epifluorescence microscopy. results: negative correlations were obtained between sperm ubiquitination and sperm count (r=-0.278, p < 0.001), sperm concen­tration (r=-0.37, p < 0.001), viability (r=-0.407, p < 0.001), sperm morphology (r=-0.509, p < 0.001), rapid progres­sive motility (a) (r=-0.246, p < 0.001) and slow progressive motility (b) (r=-0.474, p < 0.001). there was a positive correla­tion between ubiquitinated sperm and the percentage of immotile spermatozoa (r=0.486, p < 0.000). conclusion: increased sperm ubiquitination is inversely associated with good semen quality parameters, supporting the use of ubiquitin as a biomarker for evaluation of human sperm quality.