Electrophoretic separation represents a highly effective, novel approach for the isolation of spermatozoa for assisted conception purposes.

Approximately 1800 children between the ages of 5 and 12 years were randomly selected and asked whether they had present or past experiences of imaginary companions. It was found that 829 (46.2%) children reported experiences of imaginary companions. These findings were unexpected as previous studies had suggested that imaginary companions are generally experienced by fewer, much younger children. There were no significant differences in creativity scores between children who reported imaginary companions compared with those who did not. Imaginary companions were reported by more girls than boys, and were not restricted to very young children.

The electrophoretic procedure holds promise as a convenient method for the rapid preparation of high-quality spermatozoa for assisted conception purposes.

BACKGROUND: Optimization of assisted conception outcomes involves the development of rapid, safe, effective techniques for the isolation of functional human spermatozoa free from significant DNA damage. In this study we describe a novel electrophoretic sperm isolation technique that achieves these objectives. METHODS: The separation system consisted of a cassette comprising two 400 ml chambers separated by a polycarbonate filter containing 5 mmol/l pores and bounded by a 15 kDa polyacrylamide membrane to allow the free circulation of buffer. Semen was introduced into one chamber, current applied (75 mA at variable voltage) and within seconds a purified suspension of spermatozoa could be collected from the adjacent chamber. These cells were assessed for their count, viability, motility, morphology and DNA integrity. RESULTS: The suspensions generated by the electrophoretic separation technique contained motile, viable, morphologically normal spermatozoa and exhibited low levels of DNA damage. Moreover, these cell suspensions were free from contaminating cells, including leukocytes. The technique was comparable to discontinuous gradient centrifugation except that it took a fraction of the time and generated cells with significantly less DNA damage. CONCLUSION: Electrophoretic separation represents a highly effective, novel approach for the isolation of spermatozoa for assisted conception purposes.

This study examines the properties of an electrophoretic device designed to effect the rapid isolation of spermatozoa for assisted conception purposes. In light of previous reports suggesting that X- and Y-bearing spermatozoa can be separated in an electric field, the first characteristic examined was the sex chromosome status of electrophoretically isolated spermatozoa. Exploiting sex chromosome-specific differences in the structure of the amelogenin gene, a quantitative PCR protocol was designed that allowed the rapid genotyping of isolated sperm suspensions. Reassuringly, application of this procedure demonstrated that the electrophoretic method did not result in a significant skewing of the ratio of X- and Y-bearing spermatozoa. Analysis of the molecular basis for electrophoretic sperm isolation demonstrated that sperm suspensions prepared in this manner were enriched in surface sialic acid residues that bound the Sambucus nigra agglutinin (SNA) lectin. Western blot analyses demonstrated the presence of four major SNA binding proteins, three of which were identified by MALDI-Tof mass spectrometry as aminopeptidase B, fucosyltransferase and prostatic acid phosphatase. The ability of neuraminidase to significantly suppress the electrophoretic isolation of spermatozoa emphasized the causative nature of this association between cell surface sialation and sperm behaviour in an electric field. Finally, seminal plasma proteins possessing decapacitation properties were shown to co-migrate with spermatozoa during their electrophoresis, necessitating their removal prior to in vitro fertilization. In terms of function, electrophoretically isolated cells were found to capacitate normally, exhibiting high levels of tyrosine phosphorylation and a capacity for extensive binding to homologous zonae pellucidae. We conclude that the electrophoretic procedure rapidly isolates functional spermatozoa via mechanisms that are independent of their genotype but reliant upon a net electronegative charge that is largely conferred by sperm surface glycoproteins.