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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

843 タグ追加 保存
ツインテール 2014 年 11 月 28 日 に公開
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