David Deamer
David W. Deamer | |
|---|---|
| Born | April 21, 1939 Santa Monica, California, United States |
| Nationality | American |
| Education | Duke University (BS, 1961); Ohio State University (PhD, 1965) |
| Known for | Membrane compartments in the origin of life; a 1989 notebook sketch of nanopore sequencing |
| Occupation | Biochemist, biophysicist |
| Scientific career | |
| Fields | Biochemistry, biophysics, astrobiology |
| Institutions | University of California, Davis (1967 to 1994); University of California, Santa Cruz (from 1994) |
David W. Deamer (born April 21, 1939) is an American biochemist and biophysicist. He began with the structure of biological membranes and then spent about forty years on a question that grew out of it, how the first cell membranes could have formed. In a second line of work he proposed, in a notebook dated June 25, 1989, that a strand of DNA drawn through a membrane pore by an electric field might be read base by base from the change in ionic current.[1][2] He is a co-author of the 1996 paper that showed single strands of RNA and DNA crossing a protein channel, and a co-inventor on the 1995 patent application that followed it.[3][4] He joined the University of California, Davis, in 1967, and has been a research professor at the University of California, Santa Cruz, since 1994.[5]
Education and early work
Deamer took a bachelor's degree in chemistry at Duke University in 1961 and a doctorate in physiological chemistry at the Ohio State University School of Medicine in 1965.[5] A postdoctoral appointment with Lester Packer at the University of California, Berkeley, put him next to Daniel Branton, then a young professor of botany who was developing freeze-etch electron microscopy. The two published a paper on the fracture planes of a model membrane in Science in November 1967, and Damer's profile of Deamer says the results confirmed Branton's proposal that freeze-etching splits a membrane down the middle of its lipid bilayer.[1][6] Deamer moved to Davis the same year.[5]
Origin of life
On a sabbatical at Babraham, England, in 1975, Deamer talked with Alec Bangham, and the two realized that nobody had considered the origin of membranes as a requirement for the origin of cellular life. He then worked on the question for decades.[1]
His best-known experiment used a piece of the Murchison meteorite from Sherwood Chang of NASA's Ames Research Center. Deamer extracted it with chloroform and methanol, the solvent used to pull phospholipids out of membranes, put a drop of the extract on a slide and added water. In his words, he saw the water soak into the dried extract and round structures form, and a few minutes later "thin membranous vesicles begin to ooze away from the surface". He took the photographs to colleagues in the zoology department, who were having lunch down the hall; they expressed polite interest, and returned to their lunches. He published the result in Nature in 1985 under the title "Boundary structures are formed by organic components of the Murchison carbonaceous chondrite", and recalled later that he could count the requests for reprints on the fingers of one hand.[1][7]
In 2020 Deamer and Bruce Damer proposed the "hot spring hypothesis": that life began in fluctuating volcanic hot spring pools, where cycles of hydration and dehydration could make lipid-encapsulated polymers and protocells.[8] Deamer's books on the subject are First Life (University of California Press, 2011) and Assembling Life (Oxford University Press, 2019).[9][10] A 2019 profile gives his output as more than 200 research articles and reviews, cited nearly 30,000 times, and about a dozen books; it says he was president of the International Society for the Study of the Origin of Life from 2011 to 2014, and he was editor-in-chief of the journal Life from 2014 to 2016.[1]
Nanopore sequencing
In the account that Deamer, Mark Akeson and Branton published in 2016, the idea began in 1989, when Deamer "jotted a seemingly implausible idea" in his notebook: that it might be possible to sequence a single strand of DNA being drawn through a membrane's nanoscopic pore by electrophoresis. The notebook pages are dated June 25, 1989. The sketch shows three bases of a DNA strand drawn through a pore by an applied voltage, and below them the base-specific current signal that would let the sequence be read.[2]
George Church was thinking along related lines. His interest in scaling up sequencing for the Human Genome Project had led him to propose that an electronically monitored phage motor embedded in a bilayer might yield sequence information from double-stranded DNA, and he decided to pursue other high-speed methods.[2] Deamer and Branton had both noticed reports that the toxin α-hemolysin forms channels wider than 1.2 nm, enough for a single strand of DNA. In late 1993 Deamer went to the National Institute of Standards and Technology to test with John Kasianowicz whether RNA homopolymers could be electrophoresed through an α-hemolysin pore. With a positive bias above 80 mV on the trans side, numerous blockades of the ionic current lasting milliseconds appeared. With a negative bias there were none.[2]
A patent application naming Church, Deamer, Branton, Richard Baldarelli and Kasianowicz was filed on March 17, 1995 and granted as US 5,795,782 on August 18, 1998.[4] The paper by Kasianowicz, Eric Brandin, Branton and Deamer appeared in the Proceedings of the National Academy of Sciences in November 1996. It reported that an electric field could drive single-stranded RNA and DNA through a 2.6 nm channel in a lipid bilayer, each molecule appearing as a transient decrease in ionic current whose duration was proportional to its length. The abstract ended: "With further improvements, the method could in principle provide direct, high-speed detection of the sequence of bases in single molecules of DNA or RNA."[3] The longer story, from the Coulter counter to the commercial instruments, is told in History of nanopore sequencing and Nanopore sequencing.
Molecular Reality Corporation's public guide says: "In 1996, scientists showed that a single strand of DNA could be driven through a protein pore, and the dream of sequencing by blockade was born."[11] Church later invested in the company and was the first formal member of its scientific advisory board.[12][13]
Dispute over priority
The 2016 history drew a published reply from Kasianowicz and Sergey Bezrukov, who wrote that it "does not mention several key ideas, methods, and experimental results" essential to the field and "also contains several factual errors". They wrote that in 1989 one of them had tried to detect DNA with the voltage-dependent anion channel of mitochondria, and that the results were inconclusive because the channel's voltage-dependent gating made transient blockades hard to separate from noise. Deamer, Akeson and Branton answered in the same issue.[14][15]
Later work
In 2019 Deamer described himself as a founding partner of UpRNA, a start-up company in Santa Cruz that aims to transcribe base sequences from short DNA templates into short RNA molecules, siRNAs, that could fight viral infections. He said the company would use the MinION nanopore sequencer for quality control.[1]
See also
References
- ^ a b c d e f Damer, Bruce (2019). "David Deamer: Five Decades of Research on the Question of How Life Can Begin". Life 9 (2): 36. doi:10.3390/life9020036. PMID 31052584.
- ^ a b c d Deamer, D.; Akeson, M.; Branton, D. (2016). "Three decades of nanopore sequencing". Nature Biotechnology 34 (5): 518-524. doi:10.1038/nbt.3423. PMID 27153285.
- ^ a b Kasianowicz, J. J.; Brandin, E.; Branton, D.; Deamer, D. W. (1996). "Characterization of individual polynucleotide molecules using a membrane channel". Proceedings of the National Academy of Sciences 93 (24): 13770-13773. doi:10.1073/pnas.93.24.13770.
- ^ a b "US5795782A: Characterization of individual polymer molecules based on monomer-interface interactions". Google Patents. August 18, 1998. Retrieved October 25, 2026.
- ^ a b c "David Deamer". NASA Astrobiology Institute. Retrieved October 25, 2026.
- ^ Deamer, D. W.; Branton, D. (1967). "Fracture planes in an ice-bilayer model membrane system". Science 158 (3801): 655-657. doi:10.1126/science.158.3801.655.
- ^ Deamer, D. W. (1985). "Boundary structures are formed by organic components of the Murchison carbonaceous chondrite". Nature 317 (6040): 792-794. doi:10.1038/317792a0.
- ^ Damer, Bruce; Deamer, David (2020). "The Hot Spring Hypothesis for an Origin of Life". Astrobiology 20 (4): 429-452. doi:10.1089/ast.2019.2045.
- ^ Deamer, David W. (2011). First Life: Discovering the Connections between Stars, Cells, and How Life Began. University of California Press. ISBN 0-520-25832-0.
- ^ Deamer, David W. (2019). Assembling Life: How Can Life Begin on Earth and Other Habitable Planets? Oxford University Press. ISBN 0-19-064638-1.
- ^ "Keltar's Field Guide to Molecular Reality". Molecular Reality Corporation. August 2026.
- ^ Harriet Quill (September 30, 2026). "Ten Years of Hardware on About $1.6 Million". Brownian Business Daily.
- ^ Kemmishtree (March 29, 2026). "(no subject)". EQBio-OS.
- ^ Kasianowicz, J. J.; Bezrukov, S. M. (2016). "On "Three decades of nanopore sequencing"". Nature Biotechnology 34 (5): 481-482. doi:10.1038/nbt.3570. PMID 27153275.
- ^ Deamer, D.; Akeson, M.; Branton, D. (2016). "Author response to John Kasianowicz and Sergey Bezrukov". Nature Biotechnology 34 (5): 482. doi:10.1038/nbt.3561.