Shoo fly…no wait, come back!

I recently had the good fortune to find myself chatting with our Curator of Anthropology, Dirk Van Tuerenhout, about everything from the baby woolly mammoth mummy to why flies are used in genetic research. The latter of these two really got me off on an overly-excited tangent as genetics is the subject in which I hold my degree. I decided then and there to blog about the fascinating, the miniscule, the dapper dipteran…Drosophila melanogaster (the fruit fly!)

fruit-fly
 © Photo credit: Image Editor

Fruit flies have been used as a genetic model since about 1910 for a number of reasons. One of these is that they have only 4 pairs of chromosomes, which makes it easy to track mutations, for one. Also, the fruit fly’s genome has been completely sequenced since 2000. Lastly, they are relatively inexpensive and very easy to breed and maintain, and their morphology (the way they look) is easily seen with the naked eye.

I can vividly recall my first year in basic genetics lab. We had to do all manner of experiments with genes and inheritance, and we spent a significant chunk of time doing experiments with these fruit flies. Every lab table in the class got two kinds of flies to cross and see what the resulting offspring looked like. The two my partner and I received were the female wild types, just think of them as normal, red-eyed fruit flies, and the mutant dumpy wing males, which have tiny wings. Because the dumpy wing mutant cannot fly, they had an extra-difficult time mating with the females, which were fully able to fly, albeit in a 4’x1’plastic tube. We decided we felt sorry for the men of the tube and decided to offer our ‘matchmaking’ services. Really all that meant was us singing ‘selections from Marvin Gaye’s Greatest Hits to a tube of flies in a serious, crowded-yet-quiet genetics laboratory at Texas A&M. The TA got a huge kick out of it and our boys ended up as successful as the rest of the flies in the room that day! The females laid their eggs and our experimentation continued. (Side note: See! There is NO reason science has to be stuffy!)

dna
 © Photo credit: Ynse

 One of the most fascinating things about this type of research is that some Drosophila genes have homologs (genes with structural and functional likenesses) in other animals, even vertebrates like humans! My two favorites of these in Drosophila are the singed bristle gene (structural) and the Notch gene (functional). The singed bristle gene makes actin filaments cross link, the same as in human muscles. Remember, actin in humans’ muscles is imperative in allowing them to contract and move us along!

The Notch gene is involved in cellular communication in both flies and humans. This gene is the basis for development, immunity, tissue repair -basically, your cells can’t do their jobs without it. Problems with cell communication lead to diseases like cancer and even diabetes. Also, by studying and understanding the way cells talk to each other, we can offer more effective treatments and may one day be able to grow artificial tissue!!! Imagine the potential…all made possible because of legions of devoted researchers and the genes of a tiny fly.

Evolution

Evolution: a never ending process

Most scientists date the appearance of life on our planet at around 3.5 billion years ago.  A fraction of these life forms left traces, or fossil forms, for us to find. If there is one conclusion we can draw from reviewing the story of life, it is the fact that it was subject, and continues to be subject, to change.

It is safe to say that as long as there is life on our planet, it will change over time. In other words, it will evolve.

This notion of an ongoing process of change has important implications. It renders the expression of “missing link,” or “intermediate fossil” meaningless.

Quite often, scientists who study and teach evolution are challenged to show such intermediate fossils, with questions like “Mommy, Did Apes Evolve from Dogs?” Questions like these are then followed by statements like “Scientists cannot produce the fossils of half-evolved dinosaurs or other creatures.”

The challenge is clear: unless one can produce these half-evolved creatures, whatever they are supposed to look like (an ape with a dog’s head?), then the concept of evolution must be wrong. One needs to realize, however, that the way in which the question is posed is misleading.

In an earlier blog I referred to all of us a being mutants. This tongue-in-cheek statement makes the point that we are all unique because of a small number of mutations that set us apart from our parents. The mechanism that supports evolution resides in the tiny genetic changes that occur as a result of mutations – not from a sudden appearance of a different body type or part.

However, when these small changes are allowed to accumulate over vast amounts of time – say millions of years – the results can be significant. The fossil record tells us that these results were, in fact, very significant: hundreds of thousands of animal and plant species flourished and perished over the last 3.5 billion years.

Each species exhibited tiny mutations in each generation. Sometimes, the results of the mutation gave that species an advantage that allowed it to survive where others did not – thus allowing it to continue to impact the story of life on Earth.