New structure discovered in human sperm tails
A highly effective tail is needed in order for a sperm to be able to swim, and for a baby to be conceived. By using cryo-electron tomography, researchers at the University of Gothenburg -- working in partnership with researchers in the United States -- have identified a completely new nanostructure inside sperm tails, Science daily reports.
The method, for which Joachim Frank, Jacques Dubochet and Richard Henderson were awarded a Nobel Prize in 2017, produces 3D images of cellular structures.
Illustration above showing close-up of structure in sperm tail.
The tail affects the ability to swim
The tail is a highly complex machine that consists of around a thousand different types of building blocks. The most important of these are called tubulins, which form long tubes (microtubules). The tubes are found inside the sperm tail.
Thousands of motorproteins -- molecules that can move -- are affixed to these tubes. By being fixed to one microtubule and "walking on" the adjacent microtubule, the motorproteins in the sperm tail pull and the tail bends, enabling the sperm to swim.
Examining the sperm tail
The research was started in order to see what human sperm tails look like in 3D. This would then provide clues about how sperms work, in the same way that a sketch of an engine helps to explain how it operates.
What the spiral is doing there, what it consists of and whether it is important in order for sperms to swim are questions that the research team will now focus on answering.
The study, which has now been published in the journal Scientific Reports, is a collaboration between researchers at the University of Gothenburg in Sweden and the University of Colorado in the USA.