Could multicellularity in animals have been the result of endosymbiotic “fungi”?

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It has been known for some time that fungi are more closely related to animals than to plants (ref, 1997).  The split from plants occurred one billion years ago and 35 million years later the fungi and animals parted company…or did they? Candida endosymbionts can be found in a variety of beetles and even humans!

Mouse genome:  3,400 million nucleotides

Human genome: 3,300 million nucleotides

Neurospora crassa (pink bread mold),  38.6 million nucleotides, 88 full genomes could fit into a mouse nucleus.

Saccharomyces cerevisiae (bakers yeast), 12 million nucleotides, 283 full genomes could fit inside a mouse nucleus.

Eukaryotic endosymbiont of Guillardia theta, 551,264 nucleotides, ~ 6168 full genomes could fit inside a mouse nucleus.

Genes within the endosymbionts that are redundant to the host or those affecting endosymbiotic autonomy would be deleted out over time, reducing the endosymbiotic genomes still further.

Can symbionts themselves contain symbionts? They can and they do.  A classic example is the termite which contains eukaryotic protists within their gut that helps them digest wood . These protists, in turn, contain bacteria that do the actual work of digesting the cellulose. Spirochaetes can attach to the cell surface of the protists as ectosymbionts  (ref).   Visit my 1999 website and review my models on how spirochaetes acting as ectosymbionts may have led to the development of both mitosis and meiosis (figs. 30, 31, and 37).


About frankabernathy

I am a retired cell biologist and alumnus of Ohio State University. I became interested in chromosomes as far back as the 1960's when I wrote a term paper on the effects of radiomimetic drugs on chromosomes. I was fascinated at how they could break apart and reform new structures so easily. I became further involved in the early 1970's after taking a cytogenetics course at the University of Arkansas. I took that knowledge with me to Ohio State in 1980 where I eventually worked on my research and completed my Ph.D. dissertation, "Studies on Eukaryotic DNA Superstructure". My studies and later research suggested that the DNA within the eukaryotic chromosome is not the simple, linear molecular thread so widely suggested in all the classic textbooks published today. Instead, it may be the culmination of a geologically rapid set of endosymbiotic events where microorganisms plug into each other to create something greater than themselves. Feel free to contact me at
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