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  • Dr. Kim McKim: We're interested in the genes that control all the things we do, that even

  • control how we interact with the environment. So my specific interest is in cell division,

  • meiosis and mitosis. My real interest though is in meiosis, which is the way you make sperm

  • and egg, which is a special cell division which takes your chromosomes and normally,

  • everybody has two sets, you must have a backup of everything. You get two sets of chromosomes

  • and we only pass on one of them, and so this special division divides all of your genes

  • precisely in half and packages them into a sperm or an egg. The medical relevance is

  • that human infertility, particular in females, fertility goes down as women get older, and

  • women are reproducing at later and later, or older and older ages, and their fertility

  • goes down with age, and the reason is because as women get older meiosis starts to makes

  • more. The chromosomes, the genes, are not divided in half, so you get imbalance, and

  • so our work is to understand how those mistakes happen. We choose to study this in a small

  • little fruit fly. There's no moral dilemmas with working with them, so we can do whatever

  • we want, and we can do it quickly and so we get a lot of data quickly, and so fortunately,

  • meiosis happens, or meiosis uses a lot of the same instructions and proteins in almost

  • every organism that sexually reproduces. So, that means what we learn in Drosophila meiosis

  • will apply to human meiosis. Working with Drosophila, we work with it because we're

  • interested in genetics and that is an approach to biology and what a geneticist will do is

  • first of all, identify all the genes and the proteins they make that contribute to a certain

  • process. So, for example, we try to identify all of the, or most of the genes and proteins

  • that control meiosis, that make it happen. When I first started working here at Rutgers,

  • we studied a particularly gene called Mei-W68. It's a pretty boring name, because we didn't

  • know what it was. We knew it was important for meiosis, and that's because flies that

  • didn't have this gene were almost sterile, they just couldn't properly separate their

  • chromosomes and the reason was because they didn't have any of this genetic recombinations

  • as we call it, recombination process is ultimately responsible for separating all of the chromosomes

  • and genes into halves, and there's a particular gene that's required, or yeah, the protein

  • it makes is required for all of this recombination. When I started work here, it wasn't really

  • clear what that protein was, and so working on this gene, we didn't really know what it

  • was because all we knew was the flies really needed it. You go into a molecular analysis

  • and you find the DNA that is responsible for this gene, and it turned out that this gene

  • was quite important. That began a sort of train of thought that this process of how

  • recombination is initiated might be conserved in all organisms, and really based on what

  • we found in a couple of other model organisms, they then found the gene in mice and mammals

  • and that was quite an exciting time because it was when people studying mammals, mostly

  • mice, but of course humans, realized that really the basic mechanics of meiosis are

  • going to be the same. Every now and again you find a fly that has a reproductive problem

  • because they don't do meiosis very well. That gene is now very interesting to us and we've

  • spent most of my time here, as most geneticists do, doing what we call screams, trying to

  • find genes, which are important for meiosis, through this almost random mutation masse.

  • Mutation the gene, does it affect meiosis, if not we throw it away, rarely if we find

  • it, then we give it a cute name, and we start to study it. Eventually what you do is you

  • build up a collection of all these genes, that you've identified one at a time, and

  • you put them together into some sort of a pathway of instructions for how meiosis works

  • or whatever process you're studying. One of the wonderful things about meiosis is it's

  • dynamic. You can see the chromosomes come together, you can see the come apart, you

  • can see it when it goes wrong, you can learn a lot just by watching them do amazing things.

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Dr. Kim McKim - Meiosis in Drosophila melanogaster females

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    ツインテール に公開 2014 年 11 月 28 日