Research Interests
ISOECOL VII: for more information see http://www.uaf.edu/water/ISOECOL7/Welcome.html
I am interested in how naturally-occuring variations in stable isotope ratios can be used as markers for nutritional and physiological processes. A few of my current projects include:
Using Stable isotopes as dietary biomarkers in Yup'ik Eskimos
We are developing dietary biomarkers for Yup'ik Eskimos in the Southwest Alaska, using natural variations in the stable isotope ratios of subsistence and nonsubsistence foods. I collaborate with a multidisciplinary group investigating chronic disease in Alaska Natives, the Center for Alaska Native Health Research [CANHR]. Our aim is to provide accurate, unbiased dietary markers that can be used to better link dietary patterns to chronic diease in Alaska Natives. This project is funded through an NIH COBRE grant to the Center for Alaska Native Health Research at UAF , and is part of the PhD work of Sarah Nash.
15N as an indicator of tissue catabolism during hibernation This is an NSF funded project with Loren Buck and Brian Barnes. We're investigating changes in tissue 15N in hibernating arctic ground squirrels, which hibernate for 8 months in the wild and lose 20-30% of their lean mass during that time. This project is part of the PhD work of Trixie Lee.
Nutrient allocation to reproduction
Much of my previous work has investigated how nectar-feeding butterflies and moths meet the nutritional demands of oogenesis, given that their adult diets are sugar-rich and amino acid depauperate. Recent studies of reproductive resource allocation have also included fruit flies (collaborative with Marc Tatar and Kyung-Jin Min), walnut flies (PhD research of Laura Carsten Conner), and King Eiders (PhD research of Steffen Oppel, collaboratively with Abby Powell)
Publications
- Oppel, S., R. Federer, D.M. O’Brien, A.N. Powell, T. Hollmen 2010. “Effects of lipid extraction on stable isotope ratios in avian egg yolk – is arithmetic correction a reliable alternative?” AUK in press.
- Larsen T., D.L. Taylor, M.B. Leigh, D.M. O’Brien 2010. “Stable isotope fingerprinting: a novel method for identifying plant, fungal or bacterial origins of amino acids” Ecology in press.
- Nash, A.H., Kristal, A.R., Boyer, B.B., King, I.B., Metzgar, J.S., and O’Brien, D.M. 2009. “The relationship between stable isotope ratios in human red blood cells and hair: implications for using nitrogen isotope ratios of hair as a biomarker of eicosapentaenoic acid and docosahexaenoic acid.” The American Journal of Clinical Nutrition Early Online [PDF]
- Wang, Y., D.M. O’Brien, J. Jenson, D. Francis, and M. J. Wooller 2009 “The influence of diet and water on the stable oxygen and hydrogen isotope composition of chironomids (Chironomidae: Diptera), with paleoecological implications” Oecologia 160(2): 225-233 [PDF]
- O’Brien, D.M., A. R. Kristal, M.A. Jeannet, M.J. Wilkinson, A. Bersamin, B.R. Luick 2009 “Red blood cell d15N: a novel biomarker of dietary eicosapentaenoic acid and docosahexaenoic acid intake” The American Journal of Clinical Nutrition 89(3) 913-919 [PDF]
- Sears J., S.A. Hatch, and D.M. O’Brien 2009 “Disentangling effects of growth and nutritional status on seabird stable isotope ratios” Oecologia 159:41-48 [PDF]
- Oppel, S., A.N. Powell, and D.M. O’Brien 2009 “Using eggshell membranes as a non-invasive tool for investigating nutrient allocation to egg production” Journal of Ornithology 150(1): 109-115 [PDF]
- Kaufman, M.R., R.R. Gradinger, B.A. Bluhm, and D.M. O’Brien 2008 “Using stable isotopes to assess carbon and nitrogen turnover in the Arctic sympagic amphipod Onisimus litoralis” Oecologia 158(1) 11-22 [PDF]
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Wang, Y., D. Francis, D.M. O'Brien, and M.J. Wooller 2008 “A protocol for preparing subfossil Chironomid head capsules (Diptera: Chironomidae) for stable isotope analysis in paleoclimate reconstruction” Journal of Paleolimnology 40(3) 771-781 [PDF]
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O’Brien, D.M., K.J. Min, T. Larsen, and M. Tatar 2008. “Testing how diet restriction extends lifespan in Drosophila with stable isotopes” Current Biology 18(4) R155-R156. [PDF]
- O'Brien, D.M. and Wooller, M.J. 2007 "Tracking human migration using stable oxygen and hydrogen isotope analyses of hair and urine”. Rapid Communications in Mass Spectrometry 21: 2422-2430. [PDF]
- Wilkinson, M.J., Yai, Y. and O'Brien, D.M. 2007. "Age-related variation in red blood cell stable isotope ratios (d13C and d15N) from two Yup'ik villages in Southwest Alaska: a pilot study." International Journal of Circumpolar Health 66(1): 31-41 [PDF]
- Scott, J.H., D.M. O'Brien, D. Emerson, H. Sun, G.D. McDonald, A. Salgado, M.L. Fogel. 2006. "An examination of the carbon isotope effects associated with amino acid biosynthesis". Astrobiology 6(6):867-880. [PDF]
- Min, K.J., M. Hogan, M. Tatar, and D.M. O'Brien. 2006. "Resource allocation to reproduction and soma in Drosophila: a stable isotope analysis of carbon from dietary sugar." Journal of Insect Physiology 52(7): 763-770. [PDF]
- Suarez, R.W., C.A. Darveau, K. Welch, Jr., D.M. O'Brien, D.W. Roubik, P.W. Hochachka. 2005. "Energy metabolism in orchid bee flight muscles: Carbohydrate fuels all". Journal of Experimental Biology 208: 3573-3579. [PDF]
- O'Brien, D.M., C.L. Boggs,
and M.L. Fogel 2005. "The amino acids used in reproduction by butterflies:
a comparative study of dietary sources using compound specific
stable isotope analysis." Physiological and Biochemical Zoology 78(5):819-827. [PDF]
- Fisher,
K, D.M. O’Brien, and C.L. Boggs 2004 "Allocation
of larval and adult resources to reproduction in a fruit-feeding
butterfly." Functional Ecology, 18:656-663. [PDF]
- O’Brien,
D.M, C.L. Boggs and M.L. Fogel. 2004 "Making eggs
from nectar: the role of life history and dietary carbon turnover
in butterfly reproductive resource allocation." Oikos 105:
279-291. [PDF]
- O’Brien,
D.M, C.L. Boggs and M.L. Fogel. 2003. "Pollen feeding
in Heliconius charitonius: isotopic evidence for essential
amino acid transfer from pollen to eggs." Proceedings of
the Royal Society of London: B 270 (1533): 2631-2636. [PDF]
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O’Brien,
D.M., Fogel, M.L., and C.L. Boggs. 2002. "Renewable and non – renewable
resources: amino acid turnover and allocation to reproduction
in Lepidoptera." Proceedings of the National Academy of the Sciences
USA 99(7): 4413-4418. [PDF]
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O'Brien,
D.M. and R.K. Suarez. 2001. "Fuel use in hawkmoth (Amphion
floridensis) flight muscle: enzyme activities and flux rates." Journal
of Experimental Zoology 290:108-114. [PDF]
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O'Brien,
D.M., D.P. Schrag, and C. Martínez del Rio. 2000. "Allocation
to reproduction in a hawkmoth: a quantitative analysis using
stable carbon isotopes." Ecology 81:2822-2831. [PDF]
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O'Brien,
D.M. 1999. "Fuel use in flight and its dependence on nectar
feeding in the hawkmoth Amphion floridensis." Journal of
Experimental Biology 202:441-451. [PDF]
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Gannes,
L.Z., D.M. O'Brien, C. Martínez del Rio 1997. Stable isotopes
in animal ecology: Assumptions, caveats, and a call for more
laboratory experiments. Ecology 78:1271-1276. [PDF]
A few favorite bugs
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Amphion floridensis 
Euphydryas chalcedona 
Speyeria mormonia