‘The reproduction of mankind is a great marvel and mystery’ ~ Martin Luthur
This is the finished article. Feel free to educate yourself and be blown away by the intricate workings of a simple little human sperm cell. Seriously, it’s riveting stuff!
Sperm’s sprint booster demystified
Sperm cells bear a heavy burden, transmitting paternal DNA to the egg. It accomplishes this duty by relying on vigorous movement in the Fallopian tube finishing straight and conserving its limited energy resources until the final dash. Speed and timing are everything.
‘Activity depends on location within the male and female reproductive tracts’ explains Yuriy Kirichok, assistant professor at the University of California, San Fransisco. Acidic conditions of the male reproductive tract maintain sperm in an inactive state, whereas increased motility is observed when sperm are introduced to the female reproductive tract of higher pH. The linkage between sperm energetic state and intracellular, within sperm, pH is long-established but only recently have Yuriy and his team identified the mystery molecular mechanism responsible for this initiation of activity.
The main boundary to previous discovery was a direct method of observation due to the small size of human sperm cells. A delicate patch-clamp technique was used in which electrical activity across the sperm cell plasma membrane is measured. The resulting activity was similar to proton-releasing Hv1 channels present in immune cells. The Hv1 channels and sperm activity were inhibited by the presence of zinc, which is found in high concentrations in male seminal fluids. Researchers speculate that zinc inhibition is relieved whilst sperm are resting in the sticky folds of the Fallopian tubes through absorption and binding with other proteins. Furthermore endocannabinoid anandamine, a compound found in proximity to the egg and which acts in a similar way to the active components in marijuana, causes channel opening and sperm hyperactivity.
Further confirming the identity of this ‘turbo-boosting’ molecule a fluorescent stain specific for Hv1 and the presence of Hv1 mRNA, a template from which the Hv1 gene is produced, were used. Heavy staining was confirmed in the tail of the sperm showing a high density of the channels, and elevated concentrations of Hv1 mRNA in the cytoplasm. This revealing evidence verifies the machinery behind the sperm sprint booster.
Such findings give us a deeper insight into male fertility. Providing an explanation into the link between infertility and marijuana use, Kirichok speculates that ‘marijuana likely activates sperm prematurely’ causing them to burn out early eliminating them from the ‘great egg race’. Hv1 and its importance in sperm activation will make it a prime therapeutic target for controlling male fertility through tweaking sperm for boosted motility or contraceptive possibilities.