ARSENIC DNA DISCOVERY IS FLAWED: NO DNA WITH ARSENIC IN PLACE OF PHOSPHATE

Last year  NASA made a sensational claim about discovery of  DNA in which the phosphorous is replaced by arsenic.  The bacterial strain GFAJ-1 was isolated from the arsenic-rich sediments of California’s Mono Lake by its ability to grow in the artificial Mono Lake medium without phosphate but with high concentrations of arsenate. It was claimed that GFAJ-1 grew in -P medium only when arsenate was provided, and  significant amounts of arsenate were detected in subcellular fractions.  This was interpreted as “ growth due to  use of arsenate in place of phosphate”. Wolfe-Simon et al. further reported that arsenic was incorporated into the DNA backbone of GFAJ-1 in place of phosphorus, with an  estimated 4% replacement of P by As based on the As:P ratio measured in DNA samples embedded in agarose gel slices.

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This discovery claim by NASA  Scientists was sensational as

XENO-NUCLEIC ACIDS – alternatives to DNA / RNA

Genetic information storage and processing rely on just two polymers, DNA and RNA, yet whether their role reflects evolutionary history or fundamental functional constraints is currently unknown. With the use of polymerase evolution and design, a Group of Scientists have shown that genetic information can be stored in and recovered from six alternative genetic polymers based on simple nucleic acid architectures not found in nature [xeno-nucleic acids (XNAs)]. They also select XNA aptamers, which bind their targets with high affinity and specificity, demonstrating that beyond heredity, specific XNAs have the capacity for Darwinian evolution and folding into defined structures. Thus, heredity and evolution,