Prime Time Replay:
Dr. Thomas E. Johnson
on How Genes Affect Aging and Behavior
MsgId: *breakthrough(1)
Date: Wed Jul 30 20:58:44 EDT 1997
From: moderator At: 152.163.205.151
Welcome to Breakthrough Medicine. Tonight I'll be speaking with Dr. Thomas E. Johnson. Hi, Tom!
MsgId: *breakthrough(2)
Date: Wed Jul 30 20:59:42 EDT 1997
From: johnsont At: 128.138.139.32
Hi Madeline; I'm glad to be in despite the rainstorm.
MsgId: *breakthrough(3)
Date: Wed Jul 30 21:01:15 EDT 1997
From: moderator At: 152.163.205.151
Glad you could make it! I'm Madeleine Lebwohl, and tonight Tom and I will be discussing his work on how genes affect aging and behavior. Your research starts with work using mice and that useful worm, c. elegans. What is the current status of discovering how we age and how we achieve a longer lifespan?
MsgId: *breakthrough(5)
Date: Wed Jul 30 21:06:05 EDT 1997
From: johnsont At: 128.138.139.32
We have found that genes play a major role in determining life span if you happen to be a round worm. An alteration in a single gene can double your life from two weeks to four weeks.
MsgId: *breakthrough(6)
Date: Wed Jul 30 21:07:10 EDT 1997
From: moderator At: 152.163.205.151
What are the prospects for applying this to humans?
MsgId: *breakthrough(7)
Date: Wed Jul 30 21:08:46 EDT 1997
From: johnsont At: 128.138.139.32
We are very certain that human genes that play a similar role can be found. The genes that we have found in the worm do have similar genes in humans. However, we don't think that these genes play an identical role in humans.
MsgId: *breakthrough(8)
Date: Wed Jul 30 21:11:09 EDT 1997
From: moderator At: 152.163.205.151
Are you looking more at the differences or the similarities in the human and worm genes? Can any of your findings be useful to people right now?
MsgId: *breakthrough(9)
Date: Wed Jul 30 21:14:45 EDT 1997
From: johnsont At: 128.138.139.32
When one compares genes from two different species it is like comparing sentences written in two different languages. For example, compare old English with modern English. Some words are identical. Some words have changed completely and some are almost but not quite the same. Just like old English and modern English are similar and related by an evolutionary difference, so too are worm genes and human genes similar and related by evolutionary differences. If the gene is similar enough it can still be read as one can still read old English, sometimes. Thus, for example, at least one aging gene can be replaced by a human gene. One exciting result is that we have recently begun the screening of human genes to see if they can prolong worm life span. So far, at least one can.
MsgId: *breakthrough(10)
Date: Wed Jul 30 21:15:08 EDT 1997
From: guest At: 207.111.15.198
Do you think life forms are programmed to die?
MsgId: *breakthrough(13)
Date: Wed Jul 30 21:17:52 EDT 1997
From: moderator At: 152.163.205.151
We have a question from a guest. Perhaps you could answer that now.
MsgId: *breakthrough(14)
Date: Wed Jul 30 21:20:20 EDT 1997
From: johnsont At: 128.138.139.32
Organisms almost never kill themselves. It makes no evolutionary sense-and after all one of the greatest biologists said "Things only make sense in the light of evolution." Cells kill themsleves for the good of their neighbors (like to prevent their cancer from spreading) but organisms do not, in general, have the ability to evolve this type of response.
MsgId: *breakthrough(16)
Date: Wed Jul 30 21:22:44 EDT 1997
From: moderator At: 152.163.205.151
Getting back to your response, since people live so much longer than worms (right?) how much is the worm life span affected? And could we talk about this a little--sharing genes between species and seeing their effect. Can findings realistically be applied to such different species?
MsgId: *breakthrough(19)
Date: Wed Jul 30 21:25:15 EDT 1997
From: johnsont At: 128.138.139.32
Worm life spans can be doubled by some genes and only changed slightly by others. Altering most genes in the worm-or in people- results in bad effects, certainly a shorter life. Only very rarely can we find a gene that extends life when altered. We think that the class of gene that is important regulates stress resistance.
MsgId: *breakthrough(17)
Date: Wed Jul 30 21:24:58 EDT 1997
From: guest At: 207.111.15.198
Do you believe that part of our genetic "engineering" is to live for a certain length of time? Why do we wear out and die?
MsgId: *breakthrough(20)
Date: Wed Jul 30 21:26:18 EDT 1997
From: johnsont At: 128.138.139.32
Humans are clearly not programmed to die any more than is a car or a computer. Humans, cars, and computers all wear out and die. However, humans and worms, unlike cars and computers, don't have to die when a critical part fails because orgainsms can repair themselves, even without a mechanic. That's why I said earlier that the genes we found are involved in repair and why it makes sense that these genes should both make more effective repair systems and extend longevity. Worms and people do wear out and die. Repair is not perfect. Repair is a lot better in people than in worms and it's intermediate in mice (lives of two years).
MsgId: *breakthrough(22)
Date: Wed Jul 30 21:28:17 EDT 1997
From: moderator At: 152.163.205.151
What has studying how these genes affect stress shown? Can we actively limit the stresses and help the repairs?
MsgId: *breakthrough(28)
Date: Wed Jul 30 21:34:18 EDT 1997
From: johnsont At: 128.138.139.32
All the longevity genes in the worm also lead to increased resistance to enviornmental stress. All manipulations that increase resistance in the worms lead to exptended longevity. Most importantly, the only way to extend mammalian life that has been scientifcally proven to work is by a process called dieatry restriction. This process that I'll call DR involves a drastic reduction in food intake (only 40% of what a mouse would like to eat). However, it does extend life. It also makes the mouse more resistant to lots of environmental stresses.
MsgId: *breakthrough(30)
Date: Wed Jul 30 21:37:41 EDT 1997
From: moderator At: 152.163.205.151
Do you think there's a correlation in people? You did work investigating interventions that increase the response to stress and increase health. Is there a link here?
MsgId: *breakthrough(31)
Date: Wed Jul 30 21:38:55 EDT 1997
From: johnsont At: 128.138.139.32
Right now there are about 200 approved studies in which new genes are being added to human cells to achieve some medically desirable outcome. Human genetic enginerering is a reality. However, no one is tinkering with the germ line. So changeing genes is not the answer. There is a better way.We can alter the products of the genes-prteins that do the work of the cell. We can engineer proteins that will go in and affect protein function. It's this method that would be used to apply our results to humans. It would be something akin to a longevity drug.
There are a lot of studies in humans showing that a little stress is good for you. For instance, some of the early survivors of the atom bomb that were pretty far away are now doing alittle bit better than people of the same age and sex who were not exposed. There's even a name for this process; it's called hormesis. I'm convinced that hormesis is real and that some moderate stress is good-no it's essential for our well being. Let me give a few examples.
MsgId: *breakthrough(37)
Date: Wed Jul 30 21:44:12 EDT 1997
From: moderator At: 152.163.205.151
And why is stress good at certain times, bad at others? You can worry yourself sick and then prolong your life with a little stress? What is happening at the genetic level with this discrepancy?
MsgId: *breakthrough(38)
Date: Wed Jul 30 21:45:49 EDT 1997
From: johnsont At: 128.138.139.32
We have to be exposed to our environment (viruses, bacteria and the like) to produce the correct repetoire of antibodies and have a good immune system. We have to exercise to keep healthy and keep our spirits up-I think part of this is due to the stress of exercise. Even wheel chair bound nursing home residents do better after a little exercise. I think that it's moderate stress-at all times- that is needed. Obviously too much stress is damaging.None of this affects the genes-all the effects are played out at the level of the protein. Stress stimulates one protein to increase the ability to deal with further stresses and that it turn helps the cell be stress resistance and live longer.
MsgId: *breakthrough(34)
Date: Wed Jul 30 21:41:56 EDT 1997
From: guest At: 207.111.15.198
It is very interesting that there seems to be a correlation between food and longevity. Do you suppose there are sub-stances within the food we eat that damage our ability to repair ourselves.
MsgId: *breakthrough(42)
Date: Wed Jul 30 21:52:25 EDT 1997
From: johnsont At: 128.138.139.32
There are of course toxins in the food that we eat-and by the way organic produce has a MUCH higher level of many of these than non-organic food. Although the toxins are "natural". However, I don;t think that it's the toxins that are the problem. There's the program you were asking about earlier. Millions of years of evolution have programmed the body to survive starvation and the body does this by increasing its repair and stress resitance. Increased longevity is merely an unintentional by product.
MsgId: *breakthrough(41)
Date: Wed Jul 30 21:51:05 EDT 1997
From: moderator At: 152.163.205.151
So the evolutionary game plan for keeping an organism alive includes the stresses that surround it. Any ideas on how to help when something goes wrong and the stresses aren't being useful? When they cause disease? Is research going in this direction?
MsgId: *breakthrough(43)
Date: Wed Jul 30 21:55:58 EDT 1997
From: johnsont At: 128.138.139.32
A lot of us would like to be able to understand how to help a cell deal better with it. There are some companies now out there trying to make sense of this stuff-of the things we are understanding in the worm and seeing how it can be applied to humans. I think that the applications will come; we can't say when they will be. But they will!
MsgId: *breakthrough(44)
Date: Wed Jul 30 21:58:05 EDT 1997
From: moderator At: 152.163.205.151
I think we're all waiting eagerly for these answers. Tom, thank you for joining me tonight on Breakthrough Medicine. It's been great talking with you.
MsgId: *breakthrough(46)
Date: Wed Jul 30 21:58:51 EDT 1997
From: johnsont At: 128.138.139.32
Thank you Madeleine. It's been a pleasure for me also.
Home || Prime Time || Live Science || Machine Dreams || Project Open Book || SF-Fantasy-Horror
Continuum || Antimatter || Mind-Brain Lab || Interactive IQ || Gallery || OMNI ToonsQuestions, comments and suggestions can be mailed to the webmaster.
Copyright (C) 1997 by Omni Publications International, Ltd. All Rights Reserved.