The Advent of Sperm Proteomics has Arrived

Sperm proteomics is the identification and functional study of sperm proteins. It is based on the separation of proteins to generate a sample suitable for mass spectrometry and subsequent protein identification. Various proteomic approaches can be employed to study sperm proteins. Currently it has led to the identification and cataloging of thousands of sperm proteins. Ultimately, the goal is to apply sperm proteomics not only as a research method, but also as a clinical and diagnostic tool in the field of male infertility. This manuscript aims to review proteomics and the approaches used to analyze sperm proteins as well as put its application in context with some of the current findings. I. INTRODUCTION Male gametes are highly specialized cells that get pro- duced during the process of spermatogenesis in the testis. They represent a unique subtype of cells and differ drama- tically from somatic cells in general. Their crucial function remains the successful delivery of the paternal complement of genome to the oocyte. Despite spermatozoa being highly accessible cells, more in-depth studies still remain to be done on these gametes in order to elucidate their sub-cellular composition and activities in relation to their activities and function. Innovative methods and original technologies act as catalysts and driving forces for the expansion of knowledge with regards to systems and biological studies. One such emergent group of novel technologies that can be applied to study large sets of biological molecules in order to micro- measure the performance of cells at a given time is collectively referred to as omics. The term omics encompass the study of genes (genomics), transcript (transcriptomics), proteins (proteomics) and metabolites (metabolomics) (1). These technologies allow for the identification and quan- tification of cellular components in a spatiotemporal fashion. What researchers once envisioned is now a reality; omics now allows for a transformation from once only genomic analysis to proteomic analysis. This approach offers an opportunity to investigate the relationship between an organism's genotype and resulting phenotype. The specific field of proteomics allows for the measure- ment of the production of protein levels and describes the changes in all proteins expressed and translated from a single genome in a tissue or cell (2). It aims to provide the expression levels of all proteins of one functional state in a biological system (3-5). This enables researchers to gain