Sperm cell biology: current perspectives and future prospects

Major advances in biomolecular techniques as well as in the sensitivity and accuracy of mass spectrometers are transforming the scientific landscape by fueling unprecedented advances in analytical biochemistry—the 'omics revolution, which refers to the study of genes (genomics), transcripts (transcriptomics), proteins (proteomics) and the various metabolites (metabolomics). It is now possible to secure inventories of lipids, proteins, metabolites and RNA species in purified cell populations and to determine how these entities change in relation to cellular function. The humble spermatozoon is an ideal target for these new technologies because these cells can be obtained in large numbers, in an absolutely pure state and can be routinely and robustly induced to perform their major biological function—fertilization–in vitro. The spermatozoon is also an excellent target for proteomics because the functional transformation of these cells during their journey from the seminiferous tubules of the testes to the surface of the oocyte, takes place in the complete absence of contemporaneous gene transcription. Rather, functionality is conferred upon these cells by post-translational changes to their protein complement that, in turn, induce critical changes in sperm metabolism. Integrating the 'omics profiles of spermatozoa holds the key to understanding the molecular mechanisms that regulate their biology. The development of these powerful new analytical tools that include DNA sequencing, DNA microarrays, mass spectrometry and protein arrays, with user interfaces that encourage their incorporation into gamete biology laboratories, will ensure that we learn more about the cell biology of mammalian spermatozoa in the next 5 years than we have learnt in the previous 50.