and here it is, at NASA:
click image to source
'dec. 2, 2010: NASA-supported researchers have discovered the first known microorganism on earth able to thrive and reproduce using the toxic chemical arsenic. the microorganism, which lives in california's mono lake, substitutes arsenic for phosphorus in the backbone of its DNA and other cellular components.
"the definition of life has just expanded," said ed weiler, NASA's associate administrator for the science mission directorate at the agency's headquarters in washington. "as we pursue our efforts to seek signs of life in the solar system, we have to think more broadly, more diversely and consider life as we do not know it."
this finding of an alternative biochemistry makeup will alter biology textbooks and expand the scope of the search for life beyond earth. the research is published in this week's edition of science express.'
carl, how i wish you were here with us today:
'when you look more generally at life on earth, you find that it is all the same kind of life. there are not many different kinds; there's only one kind.'
'this then raises interesting questions about whether we have any idea of the possible range of life, of what could be elsewhere.'
- carl sagan, 'the varieties of scientific experience'
along the same lines of research, a shadow biosphere.
EDIT: and here's