Transcript The Third International Colloquium on Endocytobiology

The Third International
Colloquium on Endocytobiology
June 10-12, 1986
The World Trade Center
New York City
• Meeting presided over by
John J. Lee and Jerome F.
Fredrick, both on the
faculty at City University
of New York
• Presentations related to
the interrelationships
between living things: all
types of symbioses
Lee: 1933-
Fredrick: 1926-1995
Some Background on Endosymbiosis
Endosymbiotic origin of chloroplasts and
mitochondria proposed much earlier.
Endosymbiotic Origin of Eukaryotes
Schimper (1883) and
Mereschcowsky
(1905) proposed that
chloroplasts are
cyanobacteria living
inside plant cells
Andreas Franz Wilhelm
Schimper (1856-1901,
Germany)
Konstantin Sergeevich
Mereschcowsky
(1855-1921, Russia)
Mereschcowsky, a
lichenologist, rejected
the importance of
natural selection and
explained
evolutionary novelties
by acquisition of
bacteria through
symbiosis.
Mereschcowsky’s tree of life, 1910
Ivan Emanuel Wallin
• Rejected cytoplasmic
origin of mitochondria
• Considered them to be
microbes living in the
cytoplasm
• Claimed to have
cultured isolated
mitochondria as proof
of their microbial
nature
1883-1969, USA
Lynn Sagan (1967)
• On the Origin of Mitosing Cells. J.
Theoret. Biol. 14: 225-274.
• Proposed the 9+2 basal body
together with mitochondria and
chloroplasts was an
endosymbiotic microbe
• Basal body from a spirochaete, a
microbe that has multiple
microbial flagella (microtubules
of flagellin) between the two
membranes.
• Microtubular array extended
inward makes spindle and
outward becomes a flagellum
• Basal bodies also function as
centrioles
• Endosymbiosis established as a working
theory by 1986.
• Examples of symbiosis and endosymbiosis on
program
• Models of organisms that meet criteria for the
endosymbiotic process (ex: Thermoplasma, an
archean without a wall as a model for the
nuclear host)
Mixotricha paradoxa
• Trichomonad that inhabits
gut of Australian termite.
• Has two species of surface
bacterial symbionts:
spirochaetes provide
locomotion and serve as de
facto flagella
• Internal mitochondria-like
symbionts
• Together with the nucleus
and the genome of the
hydrogenosome (Hproducing ‘degenerate’
mitochondrion), they
function together as 5
genomes.
Frank Round (1927-2010, Britain)
Proposal by Frank
Round (1980).
Endosymbiosis
would make
evolutionary history
of eukaryotes
impossible to
determine
Lynn (Sagan) Margulis (1938-2011, USA)
• Scientific iconoclast
• Founder of modern
endosymbiotic theory
• Co-Founder of Gaia
Hypothesis
• Chief apologist for the 5kingdom system
• After 2008
– AIDS due to syphilis
– 9/11 conspiracy theorist
Receiving National Medal of Science 2000
F. J. R. Max Taylor
Serial endosymbiotic theory (SET (19741990)) organelles are the result of
successive engulfments…
Max F.J.R. Taylor (1939, South Africa
and Canada); eukaryote created
following endosymbiosis with
mitochondrial bacterium. Further
developed Margulis Endosymbiosis
Taylor (1976)
Ran counter to Margulis (1967) in that
organisms without flagella were most primitive
–the prevailing scientific view
Thomas Cavalier-Smith
• Proposed eukaryotes evolved
gradually from bacteria which
lost the wall and relied on
cytoskeleton for cellular
integrity
• The internal microtubular
array gave rise to flagella,
mitotic spindles, etc.
1942- Britain; Professor
emeritus, University of
Oxford
Cavalier-Smith (2010)
Figure 3 from: Philos. Trans.
R. Soc. Lond. B Biol.
Sci. 365(1537): 111–132.
The Dispersed Archaeal Eukaryome and the
Complex Archaeal Ancestor of Eukaryotes
Eugene V. Koonin and Natalya Yutin (2014)
• Host derived from
Crenarchaea
• Sophisticated
cytoskeleton
• Phagocytic
capabilities
• No wall
• Mesophylic
• Co-existed with
other bacteria
• Capture many genes
through HGT (LTG)
Archaea or Archaeon?
Endosymbiotic theory for organelle origins
Verena Zimorski, Chuan Ku, William F
Martin and Sven B Gould (2014)
Endosymbiotic theory for organelle origins
Verena Zimorski, Chuan Ku, William F
Martin and Sven B Gould (2014)
Life Ascending
Nick Lane (2009)
Complex life not inevitable
– Accident of one getting inside
another
– Accident of a selfish genome
gathering genes by HGT from
environment and symbiont then
using barriers in the cell to slow
down mRNA to splice introns
– These accidents allowed the
new cells to be larger in size and
apply a concomitantly larger set
of physiological pathways
Reader in Evolutionary Biochemistry in
the Department of Genetics, Evolution
and Environment at University College
London