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From flies to fetal viability
BBSRC-funded research on insect flight leads to better fertility prospects.
11 January 2012
Research by zoologists at the University of Oxford into how hoverflies achieve exquisite flight control has led to a means of improving in vitro fertilisation (IVF) techniques.
Studying insect flight using digital analysis of ultra-high speed photography has years later been applied to measure liquid flows around eggs retained for IVF procedures.
Fine flow measurements can help many applications.
Image: Animal Flight Group
The result is that the most viable single embryo can be selected for implantation, instead of multiple embryos being used. Clinical trials with IVF research groups from the universities of Oxford, Cambridge, and Cardiff are now under way, demonstrating how fundamental bioscience – or more specifically precise and detailed image analysis techniques – can lead to developments in seemingly unrelated field just a few years later.
Flight of the locust
Understanding how insects and birds remain upright during flight and how their wing shapes and movements contribute to their speed and manoeuvrability has long fascinated both zoologists and aircraft designers. Professor Adrian Thomas and his colleagues in the Animal Flight Group at the University of Oxford, including then BBSRC-funded PhD student Richard Bomphrey, used particle image velocimetry to measure flow velocities around flapping insect wings, and also used smoke visualisation to analyse the ways that vortexes form along the contours and leading edges of insects in flight (bees, hoverflies, locusts, dragonflies and butterflies).
Smoke reveals how air behaves around a locust in flight.
Video: A. Thomas, Animal Flight Group, Oxford University
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"We use correlation image velocimetry to analyse [air] flows in aerodynamic situations," says Thomas. "It works on any pair of images where there is sufficient structure in the image intensity across the image."
The technique analyses an image for a unique patterns of pixel intensity. It then compares the initial patterns with a second image to see where the patterns have moved. Using BBSRC funding, Thomas' team showed that details of insect wing topography, such as the way that insect wings deform during flight, are key considerations when constructing new models of flight as a whole – useful insights for aircraft and wing designers for example (ref 1). "We showed that bumblebees fly by using known high-lift aerodynamic mechanisms, with leading edge vortices over the left and right wings, and the wings working independently, which may improve manoeuvrability, but at the cost of reduced efficiency."
A few years later, the step to IVF work came from the observation that the kinds of image analysis techniques used for measuring the flows around flapping insect wings were quite general. "So we could use those techniques, with minor modifications, to measure flows in any situation where suitable images were available," says Thomas.
Fine analysis of flows associated with human eggs could help couples conceive.
So far as implantation is concerned, Thomas says that they found that the fertilised eggs showed telltale regular pulses of movement (ref 2). "The eggs with the highest viability have a regular pattern of movement-pulses that is neither too rapid, or not rapid enough."
The work has potential to have a major impact on human fertility because a critical issue in IVF is identifying the most viable embryo for implantation (ref 3). Current practices produce a large set of fertilised ova, only some of which will develop successfully. IVF clinics routinely use multiple embryos to maximise the chances of successful pregnancy; this has led to many more twin births that are associated with health issues for both the mother and the babies.
The IVF work, which has recently been patented, was funded by The Wellcome Trust. Other contributing organisations to the insect flight work include the European Research Council, MRC, EPSRC, and the US Air Force Office of Scientific Research. In addition, Thomas' image analysis software has been licensed, and negotiations are ongoing between the spin-out organisations from Oxford (Isis Innovation) and the equivalents for his collaborators at the universities of Cambridge and Cardiff.
- Details of insect wing design and deformation enhance aerodynamic function and flight efficiency (external link)
- Rhythmic actomyosin-driven contractions induced by sperm entry predict mammalian embryo viability (external link)
- Phospholipase C-ζ-induced Ca2+ oscillations cause coincident cytoplasmic movements in human oocytes that failed to fertilize after intracytoplasmic sperm injection (external link)
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