Although archaea are believed to be among the oldest organisms on Earth, finding paleontological evidence of these ancient microbes has proven elusive. At the AGU session, G. Todd Ventura of the University of Illinois-Chicago will describe what may be the earliest archaean fossil evidence yet discovered-rock samples that are 2.71 billion to 2.65 billion years old that were collected from a deep underground gold mine in Ontario, Canada. Ventura and his colleagues discovered that the rocks contained a type of lipid, or oily compound, found only in archaeal cell membranes. This finding indicates that an archaean community may have inhabited the region more than 2.65 billion years ago when the area was submerged and inundated with hydrothermal vents that eventually produced a gold deposit in what is now modern Ontario.
In another AGU presentation, Roger Summons of the Massachusetts Institute of Technology will report on the discovery of novel organic compounds recently extracted from the lipids of contemporary archaea. It is likely that many of these compounds have ''chemical structures that are new to science,'' he said.
Karyn Rogers of the Woods Hole Oceanographic Institution will discuss the effect of temperature and chemistry on archaeal communities inhabiting marine hydrothermal vents on the island of Vulcano, Italy. Several species of thermophilic archaea live in these shallow waters, where temperatures sometimes approach the boiling point. Rogers found that there were more than twice as many archaeal species at relatively moderate temperatures of 59 C (38 F) than at hotter vents where the thermometer reached 94 C (201 F).
Three AGU presentations will focus on surprising new findings about the significant im