Forums

2017 May 17

Professor Greg Fournier (MIT) - "Between RNA World and LUCA: Physiological, Ecological, and Phylogenetic Inference "

4:00pm to 6:30pm

Location: 

Haller Hall, Geological Museum, 24 Oxford Street

Abstract: 

Origin of Life studies primarily consist of two sets of inferences:  bottom-up, which infer plausible scenarios of abiogenesis given our understanding of planetary, geological, and chemical processes, and top-down, which reconstruct the evolutionary history of life for clues to its earliest states.  A discontinuity exists between these narratives, however, as deterministic physiochemical processes must give way to historic evolutionary processes before the common ancestry of any of the genetic lineages upon which top-down approaches rely.  This gap in our knowledge Read more about Professor Greg Fournier (MIT) - "Between RNA World and LUCA: Physiological, Ecological, and Phylogenetic Inference "

2017 Apr 19

Professor Jeffrey Linsky (University of Colorado Boulder), "Activity of exoplanet host stars: phenomena, physical processes, and effects on exoplanet atmospheres"

4:00pm to 5:30pm

Location: 

Geological Museum, Haller Hall, 24 Oxford Street

Abstract:

I will describe various aspects of stellar activity that control the environment of exoplanets, produce photochemical reactions in their atmospheres, and drive mass loss. The fundamental drivers of stellar active phenomena are strong magnetic fields for which field strengths can be measured by Zeeman broadening of absorption lines in stellar spectra, and the large scale magnetic geometry and properties that can be measured with Zeeman Doppler imaging techniques. Magnetic heating processes produce warm chromospheres and hot coronae. Chromospheric emission, including the Read more about Professor Jeffrey Linsky (University of Colorado Boulder), "Activity of exoplanet host stars: phenomena, physical processes, and effects on exoplanet atmospheres"

2017 Mar 02

Dr. Pascale Ehrenfreund, "Space Exploration of our Solar System: Organics for life and Habitability"

4:00pm to 6:30pm

Location: 

Geological Museum, Haller Hall, 24 Oxford Street

 

Abstract:

The search for organic material and biosignatures in our solar system is a highly complex endeavor. For life to develop, chemical raw materials are necessary, hence space missions that investigate the composition of comets and asteroids and in particular their organic content provide major opportunities to determine the prebiotic reservoirs available to the early Earth and Mars. The comet rendezvous mission Rosetta was the first spacecraft to land on a comet and thus sampling material from a cometary nucleus. Rosetta monitored the evolution of comet 67P/Churyumov- Read more about Dr. Pascale Ehrenfreund, "Space Exploration of our Solar System: Organics for life and Habitability"

2017 Jan 18

Ting Zhu, Ph.D. (Tsinghau University) "Mirror-image genetic replication and transcription"

4:00pm to 5:30pm

Location: 

Geological Museum, Haller Hall (Room 102), 24 Oxford Street

Abstract: 

 

The overwhelmingly homochiral nature of life has left a puzzle as to whether mirror-image biological systems based on a chirally inverted version of molecular machinery could also have existed. We show that two processes in the central dogma of molecular biology, the template-directed polymerization of DNA and transcription into RNA, can be catalyzed by a chemically synthesized D-amino acid polymerase on an L-DNA template. The establishment of such molecular systems with an opposite handedness is a small step towards chemically synthesizing an alternative, mirror- Read more about Ting Zhu, Ph.D. (Tsinghau University) "Mirror-image genetic replication and transcription"

2016 Dec 14

Tanja Bosak (MIT) "Mineral records of metabolisms and environmental conditions before the rise of atmospheric oxygen"

4:00pm to 5:30pm

Location: 

Geological Museum, Haller Hall (Room 102), 24 Oxford Street

Abstract:

 

Minerals, textures and shapes of sedimentary rocks may record metabolisms and environmental conditions that were present before the rise of atmospheric oxygen. For example, dolomite does not preserve fine microbial textures in modern seawater, but it commonly did so in the past. Furthermore, manganese oxides are only known to form in the presence of oxygen, so these minerals are used as proxies for the past presence of oxygen or oxygen-producing organisms. To better interpret the records of these minerals, we grew anoxygenic benthic photosynthetic microbial Read more about Tanja Bosak (MIT) "Mineral records of metabolisms and environmental conditions before the rise of atmospheric oxygen"

2016 Oct 19

Origins Forum - Nicholas Hud (Georgia Tech) "Seeking a plausible prebiotic solution for the origin of RNA"

4:00pm

Location: 

Haller Hall (Room 102), Geological Museum, 24 Oxford Street

Abstract:

The RNA World hypothesis, which posits that RNA existed before the advent of DNA and proteins, remains a popular and influential hypothesis. However, despite decades of effort, origins of life researchers are still lacking a plausible prebiotic synthesis for RNA. Persistent challenges include nucleobase selection, nucleoside bond formation, and nucleotide polymerization. We are investigating the possibility that RNA was preceded by a polymer that would have assembled more easily than RNA (i.e., pre-RNA), being comprised of different nucleobases and, perhaps, a different Read more about Origins Forum - Nicholas Hud (Georgia Tech) "Seeking a plausible prebiotic solution for the origin of RNA"

2016 Sep 21

Origins Forum - Clyde Hutchison (J. Craig Venter Institute) "Construction and analysis of a minimal bacterial cell"

4:00pm

Location: 

Haller Hall (Room 102), Geological Museum, 24 Oxford Street

Abstract: 

This talk will discuss the results presented in our recent paper (Science 351, p.1414 and online aad6253). Recent work to analyze the minimal cell, and plans for further analysis will also be discussed. We used whole-genome design and complete chemical synthesis to minimize the 1079-kilobase pair synthetic genome of Mycoplasma mycoides JCVI-sym.o. An initial design, based on collective knowledge of molecular biology combined with limited transposon mutagenesis data, failed to produce a viable cell. Improved transposon mutagenesis methods revealed a class of quasi Read more about Origins Forum - Clyde Hutchison (J. Craig Venter Institute) "Construction and analysis of a minimal bacterial cell"

2016 May 11

Origins Forum - Potassium Isotopic Evidence for the Origin of the Moon - Kun Wang (EPS- Jacobsen Group)

4:00pm

Location: 

Haller Hall

Abstract - The Earth-Moon system has unique chemical and isotopic signatures compared to other planetary bodies; any successful model for the origin of the Earth-Moon system has to satisfy these chemical and isotopic constraints. The Moon is substantially depleted in volatile elements such as potassium compared to the Earth and the bulk solar composition, and it has long been thought to be the result of a catastrophic Moon-forming Giant Impact. Volatile element depleted bodies like the Moon were expected to be enriched in heavy potassium isotopes because of the loss of volatiles to space, Read more about Origins Forum - Potassium Isotopic Evidence for the Origin of the Moon - Kun Wang (EPS- Jacobsen Group)

2016 Feb 17

Origins Forum - Origin of Archean sulfur mass-independent fractionation and its implication to Earth’s early atmosphere - (Shuhei Ono - MIT)

4:00pm

Location: 

Haller Hall

Abstract:

Signatures of sulfur isotope mass-independent fractionations (S-MIF) in Archean sulfate and sulfide minerals have been considered as the most convincing evidence for early anoxic atmosphere, and constrain the atmospheric oxygen level to less than a few ppm until before 2.3 Ga [1] [2]. Despite the critical importance in understanding early evolutionary history of atmospheric oxygen and biosphere, the source reaction(s) and physical mechanism of S-MIF are poorly constrained.  Detailed mechanistic understanding of physical origin of MIF is expected to provide critical Read more about Origins Forum - Origin of Archean sulfur mass-independent fractionation and its implication to Earth’s early atmosphere - (Shuhei Ono - MIT)

2015 Dec 16

Origins Forum - Bifacial Peptide and Polymer Nucleic Acid: Functional Integration of Abiotic Molecules with DNA and RNA (Dennis Bong- Ohio State University)

4:00pm

Location: 

Haller Hall

Abstract - We have recently reported the synthesis of bifacial peptide nucleic acid (bPNA), a peptide that uses triazine heterocycles to interface with polypyrimidines. Triazines readily form from prebiotic reaction conditions, raising the intriguing possibility of their role as informational precursors to the native bases. Bifacial PNA engages two oligo T/U strands simultaneously to form a unique triple stranded structure. Thus, bifacial PNA binding is an associative operation, bringing together non-interacting poly-T/U strands to form a bPNA triplex hybrid. We demonstrate Read more about Origins Forum - Bifacial Peptide and Polymer Nucleic Acid: Functional Integration of Abiotic Molecules with DNA and RNA (Dennis Bong- Ohio State University)

2015 Nov 18

Origins Forum - "The Formation of Organic Compounds of Astrobiological Interest by Radiation Processing of Astrophysical Ices" (Scott Sandford, NASA - Ames Research Center)

4:00pm

Location: 

Haller Hall

Abstract: 

Many environments in space contain very low temperature mixed molecular ices that are exposed to ionizing radiation in the form of cosmic rays and high-energy photons.  While traditional chemistry would not be expected to occur at the temperatures typical of these ices (T < 50 K), ionizing radiation can break bonds in the original molecules in the ices to form highly reactive ions and radicals.  These ions and radicals are subsequently free to react despite the low temperatures of the original ices.  Laboratory experiments, many of them carried out at the Read more about Origins Forum - "The Formation of Organic Compounds of Astrobiological Interest by Radiation Processing of Astrophysical Ices" (Scott Sandford, NASA - Ames Research Center)

2015 Oct 21

Origins Forum - Observation of Chiral Sensitivity in an Electron-Collision-Induced Molecular Breakup Reaction (Timothy Gay - University of Nebraska)

4:00pm

Location: 

Haller Hall

Abstract: 

"We have bombarded chiral halocamphor molecules in the gas phase with low-energy (< 1 eV), longitudinally-spin-polarized electrons, and investigated dissociative electron attachment (DEA) reactions:       

e- + HA → H- + A,

where H is a halogen atom (Br or I) and A is the residual camphor fragment.  We observe that for a given target handedness, the total DEA cross section depends on the helicity of the incident electron.  In the case of iodocamphor at the lowest incident electron energies, this effect can be as Read more about Origins Forum - Observation of Chiral Sensitivity in an Electron-Collision-Induced Molecular Breakup Reaction (Timothy Gay - University of Nebraska)

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