Effects of Pressure and pH on the Hydrolysis of Cytosine: Implications for Nucleotide Stability around Deep‐Sea Black Smokers

Lepper, Christopher P.; Williams, Martin A. K.; Penny, David; Edwards, Patrick J. B.; Jameson, Geoffrey B.

doi:10.1002/cbic.201700555

Cited by 5 publications

(3 citation statements)

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“…Samples for NMR spectra to be gathered under elevated pressure conditions were inserted into the specialised high-pressure NMR cell (Daedalus Innovations) and spectra obtained using 1360 scans. This cell comprised of a ceramic zirconia NMR tube attached to a titanium manifold and homeassembled pressurisation system [26] with low-viscosity paraffin oil as the pressurising medium.…”

Section: Methodsmentioning

confidence: 99%

Effects of Pressure and pH on the Physical Stability of an I‐Motif DNA Structure

et al. 2019

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The thermodynamic stability of a cytosine(C)‐rich i‐motif tract of DNA, which features pH‐sensitive [C..H..C]+ moieties, has been studied as function of both pressure (0.1–200 MPa) and pH (3.7–6.2). Careful attention was paid to correcting citrate buffer pH for known variations that stem from changes in pressure. Once pH‐corrected, (i) at pH >4.6 the i‐motif becomes less stable as pressure is increased (KD decreases), giving a small negative volume change for dissociation (ΔDV°) of the i‐motif – a conclusion opposite to that which would be drawn if the buffer pH was not corrected for the effects of pressure; (ii) the i‐motif's melting temperature increases by more than 30 K between pH 6.5 and 4.5, the consequence of an enthalpy for dissociation (ΔDH°) of 77(3) and 90(3) kJ (mol H+)−1 at 0.1 and 200 MPa, respectively; (iii) below pH 4.6 at 0.1 MPa (pH 4.3 at 200 MPa) the melting temperature decreases as a result of double protonation of cytosine pairs, and ΔDH° and ΔDV° change signs; and (iv) the combination of ΔDH° and ΔDV° lead to the melting temperature at pH 4.3 being 3 K higher at 200 MPa than at 0.1 MPa.

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Section: Methodsmentioning

confidence: 99%

Effects of Pressure and pH on the Physical Stability of an I‐Motif DNA Structure

et al. 2019

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“…The importance of this process stems from the fact that it serves as the ‘mother engine’ responsible for the origin of life as per some authors (Russell et al , 2013). In contrast, if the rock–ocean interface is acidic or characterized by a higher temperature, the rate of serpentinization will be significantly altered; furthermore, RNA nucleobases and amino acids have short half-lives at high temperatures and pressures (Levy and Miller, 1998; Aubrey et al , 2009; Kua and Bada, 2011; Lepper et al , 2018). In this regard, we note that it remains controversial as to whether the first lifeforms on the Earth were thermophilic (Akanuma et al , 2013; Weiss et al , 2016) or mesophilic (Miller and Lazcano, 1995; Bada and Lazcano, 2002; Cantine and Fournier, 2018).…”

Section: Energy Sources and Paths For Abiogenesismentioning

confidence: 99%

Subsurface exolife

Lingam

Loeb

2018

International Journal of Astrobiology

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We study the prospects for life on planets with subsurface oceans, and find that a wide range of planets can exist in diverse habitats with ice envelopes of moderate thickness. We quantify the energy sources available to these worlds, the rate of production of prebiotic compounds, and assess their potential for hosting biospheres. Life on these planets is likely to face challenges, which could be overcome through a combination of different mechanisms. We estimate the number of such worlds, and find that they may outnumber rocky planets in the habitable zone of stars by a few orders of magnitude. * Electronic address: manasvi.lingam@cfa.harvard.edu † Electronic address: aloeb@cfa.harvard.edu 1 As per NASA's Astrobiology Strategy: "Habitability has been defined as the potential of an environment (past or present) to support life of any kind."2 By "life-as-we-know-it", we will refer henceforth to organisms which involve carbon-based chemistry, and water constitutes the solvent.

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“…As earlier high-temperature, high-pressure lab experiments suggested, this NO 2 -(just like NO 3 -) should also be reduced to NH 4 + . Along the same line of reasoning, DON is also expected to be deaminated releasing NH 4 + at high temperature as suggested by several studies done on heat-induced deamination of amino acids (e.g., Lewis et al, 2016;Cleaves et al, 2018;Lepper et al, 2018).…”

Section: Sources and Sinks For Nh 4 + At Ventsmentioning

confidence: 76%

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The Production and Fate of Nitrogen Species in Deep-Sea Hydrothermal Environments

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Indeed, I have come so far from when I first approached him in the summer of 2012. For all that, and much more, I am truly grateful.Jeff Seewald is another person with whom I have worked very closely with through the course of this thesis. I have thoroughly enjoyed my time in his lab. Jeff spent a lot of time teaching me how to set up high-temperature, high-pressure experiments and very patiently coached me the optimized techniques and systems for sampling. In addition, he has been 'a fountain of optimism' through long hours in the lab.I would also like to thank the other members of my thesis committee: Stefan Sievert and Shuhei Ono. Stefan played an instrumental role in getting me on the 9°50'N East Pacific Rise cruise in 2017, and provided insights into the microbial dynamics at Crab Spa (yes, it is spelled correctly this time). Shuhei was always enthusiastic to hear about my thesis progress, and offered valuable advice and encouragements during our meetings. I am also indebted to Frieder Klein who not only chaired both my thesis proposal and defense, but also went above and beyond, providing suggestions to this final draft.This thesis would not have come to fruition without the expert technical assistance of Sean Sylva, whose incredible patience and recommendations helped troubleshoot both the bomb setup and instruments used for my work in the Seewald Lab. Labmates from the first summer when I first started my experiments, Niya Grozeva and Justin Snook, both provided tremendous assistance, shared neatly-kept notes, and most importantly, offered lab companionship. I am also thankful to Zoe Sandwith, who kept the IRMS in the Wankel Lab humming, dealt with leaks in the Valco valve, did the argon sniffing, and took care many other issues that would have taken much longer to fix without her help.I have benefited greatly from the body of works carried out by many colleagues. Archived samples from the Seewald Lab, which were the main part of Chapter 3, were collected during numerous cruises before I entered the Joint Program. Many of these were collected with the help of Eoghan Reeves and Jill McDermott, both former advisees of Jeff's. They have been very generous in providing sample data and insights that were instrumental to my work. Annie Bourbonnais, Marv Lilley, and Dave Butterfield generously shared their Juan de Fuca Ridge sample data, which also made up a sizeable part of the compilation. Tina Lin and Mike Rappe provided crustal fluid samples, which became great complements to the Juan de Fuca discussions. Jesse McNichol's thesis work on Crab Spa incubations laid the groundwork for development of Chapter 4 of this thesis.The world-class education I had received for my PhD would not happened without the highly acclaimed field experts at WHOI and MIT. Moreover, the Academic Programs Office had been a propelling force behind the scene. I would like to specifically thank Meg Tivey, Jim Yoder, Julia Westwater, Lea Fraser, and Christine Charette. I am also indebted to John Farrington who, despite not being the Dean...

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Effects of Pressure and pH on the Hydrolysis of Cytosine: Implications for Nucleotide Stability around Deep‐Sea Black Smokers

Cited by 5 publications

References 46 publications

Effects of Pressure and pH on the Physical Stability of an I‐Motif DNA Structure

Effects of Pressure and pH on the Physical Stability of an I‐Motif DNA Structure

Subsurface exolife

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