So hi everybody, my name is Michael Rosbash,
and I'm an investigator of the Howard Hughes Medical
Institute, and a professor at Brandeis University in the department
of biology, where I've been for 40 years. So, the friendship
aspect of this title refers to the fact that I collaborated for
more than 20 years with my colleague, Jeff Hall,
who arrived at Brandeis at exactly the same time
I did. And we formed a fast friendship. Jeff is almost exactly
my age, and we had many interests in common. And
Jeff had worked as a postdoc for Seymour Benzer,
where he met Ron Konopka, where he became fluent
with the circadian story and also worked on that himself
in his own lab, before I got involved. So that's really how
this story began. And Jeff and I, as I indicated, had many
interests in common. One -- two of them are shown here,
tobacco and alcohol. We also both were great sports fans,
and also played basketball for a decade together in a
religious-obsession with the noon-time basketball game
during that decade. And it was after the basketball games I
in the locker room where everyone cools down and showers
that we would exchange scientific stories. And Jeff
would tell me about his research in circadian rhythms that was
ongoing. And it's really that friendship and those tales
which were the backdrop for this story. So to tell you
just a little bit about circadian biology, as shown here
is the wheel running activity of hamsters recorded
on an old machine and then plotted as a function of time
of day, from the top to the bottom. And all animals have some
circadian rhythms, from fungi to man. And they're commonly
assayed in constant darkness. And the rhythms, the
intrinsic rhythms of animals, are not precisely 24 hours
-- they're about 24 hours, a little slower, a little faster.
Hence, the term "circadian" or "circa dia," about a day.
And shown here, is the rhythm of these rodents in constant
darkness, which is a little faster than 24 hours, as indicated by
every day starts a little bit earlier than the day before.
And in a light-dark cycle, however, shown at the bottom
panel, where there's 12 hours of light and 12 hours of darkness,
then the animal locks on to the light-dark cycle in the incubator
as we lock onto a light-dark cycle from the external world.
The set rising and setting of the sun, and temperature cycles
can also do this as they accompany the light-dark in the external
light-dark cycle. You'll notice here also, that these animals
are nocturnal, their activity coincides with the night, they
sleep during the daytime, and that's a characteristic of any
but not all rodents. Now the star of our show is Drosophila
melanogaster, as shown here using a primitive counting
apparatus to keep time. This is drawn by my daughter, who is
a graphic designer. And here's a picture of Drosophila
locomotor activity rhythms, the analog if you like, of the
hamster's wheel running activity. And what's shown are the
fact that these animals, insects -- most insects, in general,
are active at dawn and dusk, with a morning peak
and an evening peak of activity. In this case, in an
incubator, so the morning peak coincides with the appearance
of light, whereas the evening peak coincides with the
transition from light to dark. And the arrows refer to
the fact that the activity ramps up in advance of those
discontinuous incubator transitions, indicating that there's
really a timing mechanism that can anticipate the change
in the external world's conditions. And anticipation
is the name of the game in circadian rhythms. It's
more advantageous to know what's going to happen
than to know what has just happened. And so that's
really what the circadian system contributes to the animals,
one of several things. So genetics, in terms of addressing
this kind of problem, has had some negative history, especially
in the first half of the 20th century. For example, the eugenics
movement, in which people of low intelligence, handicapped,
or even of some disfavored races at the time, were
inhibited from procreating, in some cases exterminated
as you all know from Nazi Germany. So this movement
gave behavioral genetics, gave intrinsic properties of
animals or people, a bad name. And similarly, the psychologist
B.F. Skinner, who had a long and distinguished career at Harvard,
had a tremendous amount of influence and believed that one
could change the behavior of virtually every individual
by simply subjecting them to constraining conditions,
which would then change their behavior. Meaning
that intrinsic behavioral features were not really, were not really
fixed. And so, of course there's positive history, especially
in the latter half of the 20th century that offsets that preceding
negative history. We know that we can breed plants
in order to enhance certain characteristics, that's also
true for animals, cattle, dogs, etc ... And of course,
the 1973 Nobel Prize was awarded to three scientists
who really worked on animal behavior as intrinsic
to those particular species. So the landscape shifted,
I would say, as the 20th century progressed.
And so, the question for you and for me, is
why use genetics to try and address the problem like
circadian rhythms? And I want to emphasize that this is
different from the nature/nurture problem, we're not
trying to debate how much of circadian biology is inherited,
and how much can be environmental. Nor whether
you're rhythm is different from my rhythm because of genetic
features or environmental features. We're using genetics
as an entree into this process. Can we figure out what
keeps time by finding mutants which disrupt that process?
And therefore will provide access to the genes and the proteins
which underlie the process. And to emphasize this distinction,
let me point out to you that even learning, the ultimate
in nurture, if you like, relies on proteins and therefore,
relies on genes. So genetics, genes, proteins are
inherent in everything. So I turn now to the studies of Konopka
and Benzer, who identified clock mutants of Drosophila
melanogaster in this landmark paper published in 1971.
So they fed fruit flies mutagens to increase frequency
of mutations and then screened those flies for aberrant
circadian properties. And they came up with three mutants
in single gene, all three were alleles of one gene,
which either gave rise to an absent clock, that is no
rhythm what so ever, a short period clock, which ran
fast, or a long period clock, which ran slow. And all
three of those, as I said, were single mutations, single
nucleotide changes in the same protein, which they named
Period, which suggested of course that this protein had some
important role in the timekeeping process. But it was really
-- and here's an example of the wild type circadian pattern
on the left, or the per short pattern on the right. And the
vertical line refers to the fact that the lights were turned
off. And you'll notice that the wild type fly, on your left,
keeps very good time during the course of the subsequent
days, that is almost exactly 24 hours. Whereas the per short
mutant strain, every day advances the period by several
-- advances the beginning of activity by several hours
hours by comparison to the day before. Very similar to
the hamster phenotype, as I said before, only more
profound, since this animal has a 19 or 20 hour period
as contrasted with the almost precise 24 hour period
of the wild type. So, how does one get at this problem?
And there was really almost a 15 years between the
publication of Konopka and Benzer and the appearance of
recombinant DNA, which could be applied to this problem
where the Period gene could be cloned and sequenced
to try to ask what might this gene be doing?
And so I was working on recombinant DNA in my laboratory
on studies on yeast gene expression, Jeff Hall had not
yet adopted this technology. So during one of these
basketball games, I suggested to Jeff that we get
together, that we collaborate and that we try to clone
this gene, our two laboratories, to see if we could
figure out what it was doing. And we did that at the same time
Mike Young's laboratory at the Rockefeller University also
accomplished the same task. And unfortunately, this protein
was a pioneer protein, as the expression goes, it
had no relatives in the database. These were early days
for DNA sequencing, there were a limited number of proteins
that had been sequenced and identified, and so we
were left still with the question of what this protein
did. And it was Paul Hardin in his explorations of the Period
gene's expression, where he discovered that the Period
messenger RNA underwent strong circadian oscillations
in time, so messenger RNA levels increased and decreased
by about a factor of 10. With a precise 24 hour period
even in constant darkness, and remarkably, shown in
blue, the per short messenger RNA, different, I remind you
by only one single nucleotide from the wild type or normal
strain, had only 20 hours between their peaks, just like
its behavior as compared to this 24 hour difference in
the wild type. So the RNA reflected the behavior and
we proposed that the protein must feed back onto its
messenger RNA somehow, and that that was intrinsic
and important for the timing process. But we didn't know
at what level this occurred. We didn't know whether this
was transcriptional in origin, yet the focus on gene expression
was something I was very familiar with and knew that the
half lives of mRNAs in higher organisms were generally
in the hours or even tens of hours range. Something that
was perfect for being related to circadian timing.
And then a publication in 1988 by Steve Crews and
colleagues identified a Drosophila transcription factor
named Single Minded, which had homology with the period
protein. And that set us off on an expedition to rapidly
see if transcription was part of the story.
And sure enough, within the next two years, we were able
to show through several independent kinds of investigation,
that the Period protein was nuclear and it affected transcription
and therefore, we could propose that the feedback
loop was direct and was transcriptional on origin.
And over the subsequent six years or so, the circadian
field really exploded. And both identified the positive transcription
factor, responsible for the synthesis of these regulators,
led by Takahashi and his colleagues in mammalian studies.
Followed very quickly by genetic studies in my lab and
others. And in addition, people made the leap between flies
and mammals, showing for example, that the Period protein
was conserved and had a relative, a very close relative in mammals
which did very similar, if not identical job. So there was
really a grand synthesis, if you'd like, and this story
has held up for the 17 years since 1998. And so
the question, the summary if you will, is what do I draw
as a personal conclusion from this journey of mine?
And I would say, both from the nature and nurture
standpoint, I've been incredibly lucky, from the nurture
point of view, I went to Brandeis almost by accident.
It was not a very well-considered decision, and Brandeis
has been a wonderful place to do work. I've had great
people who have come to my lab. I met Jeff Hall, to collaborate
and my colleagues in the administration have been remarkably
supportive and allowed me to undertake this thrilling
enterprise. The NIH and in particular, HHMI, which has
funded me for the last 25 years, have really been a wonderful
source of support. HHMI funds people and not projects.
Meaning I could more or less do whatever I wanted.
And was able to accomplish this. I've had a very supportive
family, that despite my obsessions loved me and allowed me to
pursue this. And finally, let me emphasize that even from
the nature point of view, whatever talents we individually
bring to a problem, those talents, what we inherit from our
parents, as we say, those parents are not -- those genes are not
by choice, we are all victims of accident. In my case,
a happy victim. And so it's really good fortune that underlies
this story. Thank you very much.