Yale Bulletin and Calendar

August 26, 2005|Volume 34, Number 1

Graduate student John Vanden Brooks is pictured with some of the alligator eggs he is using in his studies.

Study: Alligator eggs show effect
of oxygen on development

The development of bone structures in alligator eggs raised under varying oxygen concentrations creates a link to fossil records of the evolution of vertebrates and prehistoric atmospheric oxygen concentrations, according to a paper presented by a Yale graduate student on Aug. 8 at the Earth System Processes 2 meeting in Alberta, Canada.

"Alligator eggs are an ideal self-contained unit for studying the effects of oxygen on development -- they have a limited food source in the yolk and they are incubated in their nesting material at a constant temperature of 89°F and 100% relative humidity," said John Vanden Brooks, a graduate student in the Department of Geology and Geophysics.

He noted that large-scale changes in atmospheric partial oxygen pressure would have had wide-ranging effects on vertebrate evolution and development throughout geologic time.

Understanding the environment's effect on vertebrate evolution and development is considered essential to the study of ecology, paleontology and evolutionary theory. Scientists know that oxygen is the most important component in the atmosphere for all vertebrate animals, and while the rise in oxygen level during the Precambrian era has been widely studied, little attention has previously been paid to continued fluctuations throughout the Phanerozoic.

Vanden Brooks' mentor, Robert A. Berner, the Alan M. Bateman Professor of Geology and Geophysics, characterized the range of atmospheric oxygen levels over multimillion-year times scales, and established an upper value of about 31% oxygen, and a sharp decline near the Permo-Triassic boundary to about 12%. Earth's current atmosphere is about 21% oxygen.

"Each clutch contains 30 to 50 eggs that are laid together, so easy comparison can be made between sibling eggs raised under different partial pressures of oxygen," said Vanden Brooks. Studying five different partial oxygen pressures across this broad range, he found an optimum at 27% oxygen. He found that both high and low oxygen levels altered growth patterns and affected the timing and extent of bone development, its chemical composition, and mortality of the developing eggs.

While it is well known that oxygen balance is important in human premature infant development, this work provides an important step in understanding the complex interaction between vertebrate development and oxygen levels, said Vanden Brooks.

The Earth System Processes 2 meeting was co-sponsored by the Geological Society of America and the Geological Association of Canada. Eggs were made available by Ruth Elsey of the Rockefeller Wildlife Refuge in Louisiana. The study was funded by the Geological Society of America, the Paleontological Society, the American Museum of Natural History, the American Philosophical Society, the National Science Foundation, Yale Institute for Biospheric Studies, and the Ecology and Systematics of Animals on the Verge of Extinction Fund.

-- By Janet Rettig Emanuel

T H I SW E E K ' SS T O R I E S

Margaret Grey is named dean of School of Nursing

Benson to step down as dean of School of Art after this year

Team discovers new planet in the outer solar system

Grant will fund center for study of nervous system

Study: Alligator eggs show effect of oxygen on development

Yale Librarian Prochaska appointed to a second term

New master's program prepares nurses for leadership roles

Exhibit explores the 18th-century 'worlds' of Francis Wheatley

Private portrait miniatures showcase the faces of public figures

Gallery hosting festive open house . . .

Architecture gallery to feature traveling art show 'Ant Farm'

Sterling Library launches new academic year with two exhibits

Researchers create powerful tool for decoding gene functions

Galapagos tortoises more diverse than once believed, say scientists

Team identifies 'signatures' of protons in water

'Canary Database' shows animals offer health warnings for humans

Team digitally reconstructs long-extinct 'Lamp Shell'

'Gene trapping' reveals how flower development is controlled

Discovery may aid development of treatment for melanoma

Drinking alcohol may lower risk of non-Hodgkin's lymphoma

Lyme disease prevention program launched in Connecticut

For 35 students, summer was a time of service in New Haven

IN MEMORIAM

John Ostrom: He revolutionized field of paleontology

Robert Abelson: Psychologist was adviser to presidential candidates

Greer Allen: University printer was inspiration to School of Art students