Flies’ Flight Factor

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Flies’ flight factor found, according to reports in ScienceDaily and Nature vol. 479, p406, 17 November 2011, doi:10.1038/nature10559. Flies have relatively small wings for their body size, but they have incredibly efficient wing muscles that can maintain an extremely rapid wing beat, which is the reason for the buzzing sound made by flies. In order to beat at this ultrafast speed, fly wing muscles have a different structure to their other muscles and are stimulated to contract in a different way.

Most muscles contract when they receive a stimulus from the nervous system. Fly wing muscles also contract in response to being stretched. A fly has two sets of wing muscle cells. One set pulls the wings downwards. As they do this they stretch the other muscles, whose function is to pull the wings up. The stretch stimulates the upward muscles to contract, which in turn stretches the downward muscles, and the cycle starts again. Scientists at the Max Planck Institute of Biochemistry in Germany have now found the genetic switch that turns on the cellular machinery needed to build these specialised stretch-activated muscles. This factor has been named Spalt major, and without it developing flies will not build their special flight muscles. Instead, they will make muscle cells identical to the rest of their body and will then be unable to fly. Spalt is a transcription factor, i.e. it regulates which genes are turned on and off as the cell makes and assembles contractile proteins. According to the researchers “Spalt function is conserved in insects evolutionarily separated by 280 million years.” They also suggest the function of Spalt has been “potentially conserved in the vertebrate heart” as heart muscle cells also contract in response to being stretched.


Editorial Comment: Since this transcription factor is found in the genetic code of all cells, the really tricky question is: what activates ‘Spalt major’ in cells that are developing into flight muscles, yet keeps it turned off in all other muscle cells? If all cells were flight muscle activated, the end result would again be an insect that couldn’t move properly. For such a system to work there has to be a master plan determining which bits fly and which bits don’t. There has to be an advance plan for the whole fly put there by a creative designer outside the fly. Evolution, with its naturalistic chance random processes, is no help in sorting this one out.

This study also reminds us that the regulation of genes is just as important as the genes themselves when it comes to building a body. Therefore, all comparisons of the genomes of different living things must consider the way genes are controlled, e.g. the activating factor Spalt major, as well as the genes for the components that will be activated such as the proteins that form the muscles. Component genes tend to be very large because structural proteins, such those in muscle cells, are enormous. Control genes on the other hand can be very small, but they can be responsible for the large differences in body structures and functions, just like small switch in a large machine. Hence the 98.4% similarity claim for Chimps and Man is meaningless.

Did you notice the evolutionary use of the word “conserved”. “Conserved” genes are often used as evidence for evolution, however, what they really mean is they have found the same gene in many different insects, and a similar gene in vertebrates, so they assume it has been passed down during evolution. Hence, it is not evidence for evolution but an interpretation that assumes evolution. (Ref. design, insects, genetics)

Evidence News 7 December 2011