Bacteriophage [Compatibility Mode] (2)

7/27/2019 Bacteriophage [Compatibility Mode] (2)

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20:20:20:20: BacteriophageBacteriophageBacteriophageBacteriophage

STSC123: Darwins Legacy Lecture 20


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20: Outline

Bacteriophage

20.1 Viruses

20.2 Delbrck and

Phage group

20.3 Community and the Rise

of Molecular Biology.


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20.1 Viruses


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Cash Crop in Danger Tobacco was cash crop and also legal tender

throughout the world

Heavily cultivated in monoculture fields

Tobacco Mosaic Disease first described inAmerica in Virginia area in late 19th century.


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Tobacco Mosaic Disease

1879 A. Mayer names this Tobacco Mosaic

Disease

1892 D. Ivanowski demonstrates that TMD

cannot

1898 M.W. Beijerinck TMD is neither bacteria

or corpuscular body but something else henames a contagium vivum fluidum


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Tobacco Mosaic Virus Abundantly produced in the

infected plant

Not transmitted by other vectors

Infected lants have visible

malformations

First virus to be purified and

crystallized(1935), detected in

analytical ultracentrifuge (1936),

and to be visualized in an

electron microscope (1939)


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Bacteriophage

Doctors in India notice cholera bacilli

destroyed by something in the Ganges

First theorized in 1915 by Frederick Twort

ept. , x e re e namesbacteriophage- bacteria eater- and recounts a

story of the dramatic recovery of a man with

dysentery cured by bacteriophage. Parasites versus chemical catalysts


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Two Directions

1. Clinical Applications

- University Systems and Government

- Pasteur Institute

- medical schools

2. Basic scientific experimentation

- Rockefeller Foundation- California Institute of Technology


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Rockefeller Foundation Science of Man funding program

eugenics pre WWII/molecular biology postWWII

Warren Weaver funnels money

into biology that is interdisciplinary-chemistry/physics/biology

Post 1953, the Nobel Prize was given to 18

scholars for molecular biology research; 17funded by Rockefeller Foundation underWeaver


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Emory Ellis

- Emory Ellis, a chemist, uses

phage to investigate tumorgrowth.

-

replicates itself.

- Follower of de Hrelle

- works with virus that infectse.coli


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From the beginning, our interest was in

growth processes, and not in classifying

different races of phage, or in findingmedical uses for them. It was fortunate that

the phage isolated was one which dHerelle

Model System

wou ave ca e v ru ent. Its a sorpt on tobacteria in young dense cultures was rapid,

making it possible to start growth of a parent

phage population with reasonable

simultaneity, so that their progeny might

graduate from the infected bacterial cells

also with a reasonable degree of simultaneity.


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Model System

Standardized organisms

Prototypes within which keybiological questions are askedand resolved

Technologies that study them

Self reinforcing qualityThe more people study them,

the more they are used, theeasier they are to use in studies


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20.2 Max Delbruck and the phage

group


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Max Delbruck- Born in Berlin-

1906

- Studied Physics

in Gttingen

-

- 1930-post

doctoral work

with Max Bornin Copenhagen


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Complementarity

-Multiple ways of

seeing a problem-Experimentation

natural occurrence

- paradoxes lead to

new avenues of

thinking

How can you apply this to Biology?


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Early Biology Work

-1932- back to Berlin to work withOtto Hahn and Lise Mietner

-Joins biology discussion group with

Russian Drosophila geneticist N.Timofeeff-Ressovsky and physicist

K.G. Zimmer

-Physical nature of the gene andeffects of radiation upon it


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On the whole, the successful theories of biology

always have been and are still today simple and

concrete. Presumably this is not accidental, but isbound up with the fact that every biological

henomenon is essentiall an historical one one

A Physicists Want Ad

unique situation in the infinite total complex oflife.

Such a situation from the outset diminishes the

hope of understanding any one living thing by

itself and the hope of discovering universal laws,

the pride and ambition of physicists.


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Take for instance, ordinary classical genetics of

some higher organism. We find that heredity is

controlled by genes linearly arranged in

chromosomes, and it might seem that the

Continued

pro em o repro uct on as een re uce tothat of the reproduction of the genes, but this is

not true because no gene has been observed to

reproduce except within the intact functionalcell. We have every reason to believe that this

dependence on the intactness of each cell is an

essential one.


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The fact that there are many different genesin each cell, and that we have learned to

combine different sets of enes in

Continued

hybridization experiments, teaches us thatthe thing that is reproduced is a complex

thing, but does not teach us how to break

down the problem into simpler problems.


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Move to CalTech- Accepted as a post-doctoral fellow for

Rockefeller Program- Welcomed into Morgans fly lab

-

Did he want to work on flies orwas he already leaning towardphage?


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Ellis and Delbrck- One Step Growth

Curve 1939

- Confirms de Herelles theories of virusreplication process

- mathematicall anal zes that rocess

- Helps Delbruck decide that the latent period

of the virus life cycle is worth further study.


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Salvador Luria- Born in Turin, Italy in 1912

- Studied Medicine atUniversity of Turin

- Fled Fascist Ital in 1938

and with help of EnricoFermi, was awarded a

Rockefeller Fellowship at

Columbia University


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Luria-Delbrck Experiment (1943)- Fluctuation Test

- Last Bastion ofLamarckism

- mutations in absence of

se ec on pressures

(bacteriophages)

-Constant rate of random

mutations in bacteria

populations

-Darwins natural selection

applies to bacteria


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Delbrck-Luria-Anderson (1943)-T.F. Anderson working

with RCA electron

microscope-Luria and Delbrck

become interested in

taking micrographs ofphage

-Public first micrographs

of phage-Raise questions- tails?

Mobility? Living or dead?


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Alfred D. Hershey-Born in Owosso,

Michigan

-Ph.D. in bacteriology

Michigan State University

-

Washington University inSaint Louis

-moved to Cold Spring

Harbor in 1950-Carnegie Institute

director 1962


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Hershey- Delbrck Phage

Recombination (1946) Working independently, they discovered that

introducing multiple strains of virus to bacteriacaused these viruses to recombine with eachother.

genetic recombination in T2when cells wereinfected simultaneously with several h andseveral r mutant particles, they produced not

only those two types but wild-type and hr doublemutants as well.

Beginning of phage genetics. Hershey and RaquelRothman man T2 phage genome (1948-49)


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Hershey Laboratory-Did not love

technology.

-Man of few words in

laboratory

- a on y one ot erworker in lab during

early years at Cold

Spring Harbor:Martha Chase


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Chase-Hershey Blender Experiment (1952)


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Blender Experiment continued Used radioactive sulfur isotopes to label protein

coat of virus; Used radioactive phosphorousisotopes to label DNA of virus. (two separate

cultures; two separate experimental steps)

Allows phage to infect bacteria Puts this into blender until bacteria and virus

proteins separate

Sulfur found in supernatant, phosphorous foundwith bacteria cells- can be isolated to create more

infective phage stock.


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20.3 Community and the Rise of

Molecular Biology


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Rise of Molecular Biology Unity of life common to all organisms

Employed simple biological systems-primarilybacteria and viruses- as model systems applicable

Generally looked for mechanisms of upward

causation

Borrowed methods from physics, mathematics,and chemistry as well as genetics, embryology,

physiolo0gy, immunology and microbiology


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Molecular biology continued Based on protein paradigm- salient features of

life can be explained by the structures andfunctions of protein molecules

Could only be investigated with sophisticatedand complex apparatus


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Tools of the Trade Microscopes

Petri dishes Autoclaves

Electron microscopes

Ultracentrifuges Electrophoresis

X-ray diffraction

Isotopes

Scintillation counters


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Social structure of research Interdisciplinary nature of problems

Interdisciplinary nature of people Cost of equipment

Led to a prizing of cooperation and a

heightened sense of scientific problems as groupproblems


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Social Structure In the early days I had not ultimate goal in research

except to see how life processes work. Once started

with bacteriophages, I continued research on thembecause it seemed that here one could do moreinteresting experiments than with any other material.

,

these viruses was highly compatible; among ourselveswe saw , and still see, very little competitive secrecyand back biting: we were all interested in cooperatingwith each other to promote the work as a whole.

-Thomas F. Anderson


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Cold Spring Harbor-Phage Courses begin in ColdSpring Harbor in 1945-Runs for 26 years


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California Institute of Technology

Max Delbrck

returns in 1947 The Vatican


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"The Phage Church, as we were sometimes

called, was led by the Trinity of Delbrck,Luria, and Hershey. Delbrck's status as

him the pope, of course, and Luria was thehard-working, socially sensitive priest-

confessor. And Al (Hershey) was the saint."


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Bacteriophage [Compatibility Mode] (2)

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