The Third International Colloquium on Endocytobiology

June 10-12, 1986The 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 (H-producing ‘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 5-

kingdom 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 (1974-1990)) 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 theComplex Archaeal Ancestor of EukaryotesEugene 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 originsVerena Zimorski, Chuan Ku, William F

Martin and Sven B Gould (2014)

Endosymbiotic theory for organelle originsVerena Zimorski, Chuan Ku, William F

Martin and Sven B Gould (2014)

Life AscendingNick 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