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Re: La NASA encuentra vida extraterreste
Ahí 'stá, pa' que no digan:
"Our data show arsenic-dependent growth by GFAJ-1 (Fig. 1). Growth was accompanied by arsenate uptake and assimilation into biomolecules including nucleic acids, proteins and metabolites (Table 1 and 2, Figs. 2 and 3). In some organisms, arsenic induces specific resistance genes to cope with its toxicity (7); while some dissimilatory arsenicutilizing microbes can conserve energy for growth from the oxidation of reduced arsenic species, or ”breathe" AsO4 3-, as a terminal electron acceptor (18). Our study differs because we used arsenic as a selective agent and excluded phosphorus, a major requirement in all hitherto known organisms. However, GFAJ-1 is not an obligate arsenophile and it grew considerably better when provided with P (Fig. 1A, B). Although AsO4 3- esters are predicted to be orders of magnitude less stable than PO4 3- esters, at least for simple molecules (8), GFAJ-1 can cope with this instability. The vacuole-like regions observed in GFAJ-1 cells when growing under +As/-P conditions are potentially poly-β-hydroxybutyrate rich [as shown in other Halomonas species (19)] which may stabilize As(V)-O-C type structures because non-aqueous environments appear to promote slower hydrolysis rates for related compounds (8). We propose that intracellular regions or mechanisms that exclude water may also promote this stability.
We report the discovery of an unusual microbe, strain GFAJ-1, that exceptionally can vary the elemental composition of its basic biomolecules by substituting As for P. How arsenic insinuates itself into the structure of biomolecules is unclear, and the mechanisms by which such molecules operate are unknown."
(1 September 2010; accepted 8 November 2010
Published online 2 December 2010; 10.1126/science.1197258
Include this information when citing this paper)
Ahí 'stá, pa' que no digan:
"Our data show arsenic-dependent growth by GFAJ-1 (Fig. 1). Growth was accompanied by arsenate uptake and assimilation into biomolecules including nucleic acids, proteins and metabolites (Table 1 and 2, Figs. 2 and 3). In some organisms, arsenic induces specific resistance genes to cope with its toxicity (7); while some dissimilatory arsenicutilizing microbes can conserve energy for growth from the oxidation of reduced arsenic species, or ”breathe" AsO4 3-, as a terminal electron acceptor (18). Our study differs because we used arsenic as a selective agent and excluded phosphorus, a major requirement in all hitherto known organisms. However, GFAJ-1 is not an obligate arsenophile and it grew considerably better when provided with P (Fig. 1A, B). Although AsO4 3- esters are predicted to be orders of magnitude less stable than PO4 3- esters, at least for simple molecules (8), GFAJ-1 can cope with this instability. The vacuole-like regions observed in GFAJ-1 cells when growing under +As/-P conditions are potentially poly-β-hydroxybutyrate rich [as shown in other Halomonas species (19)] which may stabilize As(V)-O-C type structures because non-aqueous environments appear to promote slower hydrolysis rates for related compounds (8). We propose that intracellular regions or mechanisms that exclude water may also promote this stability.
We report the discovery of an unusual microbe, strain GFAJ-1, that exceptionally can vary the elemental composition of its basic biomolecules by substituting As for P. How arsenic insinuates itself into the structure of biomolecules is unclear, and the mechanisms by which such molecules operate are unknown."
(1 September 2010; accepted 8 November 2010
Published online 2 December 2010; 10.1126/science.1197258
Include this information when citing this paper)
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