Evidence that acetyl phosphate functions as a global signal during biofilm development

We used DNA macroarray analysis to identify genes that respond to the status of the intracellular acetyl phosphate (acP) pool. Genes whose expression correlated negatively with the ability to synthesize acP (i.e. negatively regulated genes) function primarily in flagella biosynthesis, a result consistent with observations that we published previously (Prüß and Wolfe, 1994, Mol Microbiol 12: 973-984). In contrast, genes whose expression correlated positively with the ability to synthesize acP (i.e. positively regulated genes) include those for type 1 pilus assembly, colanic acid (capsule) biosynthesis and certain stress effectors. To our knowledge, this constitutes the first report that these genes may respond to the status of the intracellular acP pool. Previously, other researchers have implicated flagella, type 1 pili, capsule and diverse stress effectors in the formation of biofilms. We therefore tested whether cells altered in their ability to metabolize acP could construct normal biofilms, and found that they could not. Cells defective for the production of acP and cells defective for the degradation of acP could both form biofilms, but these biofilms exhibited characteristics substantially different from each other and from biofilms formed by their wild-type parent. We confirmed the role of individual cell surface structures, the expression of which appears to correlate with acP levels, in fim or fli mutants that cannot assemble type 1 pili or flagella respectively. Thus, the information gained by expression profiling of cells with altered acP metabolism indicates that acP may help to co-ordinate the expression of surface structures and cellular processes involved in the initial stages of wild-type biofilm development

Austin Papers: Series IV, 1828-1829

Copy of transcript for three letters, written in December 1828, and one written in July of 1829. The first, from Stephen F. Austin, on December 9, 1828, claiming a mine he discovered. The second is from Tomas M. Duke on December 10, 1828, and the third is from Stephen F. Austin on December 13, 1828. The last, from Juan Martines and Pedro Vidaurri to Stephen F. Austin, on July 3, 1829, gives him control of the mine

The Benzylidenecarbene–Phenylacetylene Rearrangement: An Experimental and Computational Study

Benzylidenecarbene was generated from a new photochemical source, 1-benzylidene-1a,9b-dihydro-1<i>H</i>-cyclopropa­[<i>l</i>]­phenanthrene, in deuterated benzene at ambient temperature. The carbene undergoes a facile rearrangement to phenylacetylene and could not be trapped by olefins. Generation of the carbene bearing a ¹³C label at the β-carbon produced phenylacetylene in which the label was found exclusively at the carbon adjacent to the phenyl ring. This overwhelming preference for H shift is consistent with B3LYP and CCSD­(T) calculations. The label distribution observed in this work, however, contrasts previously reported high-temperature flash vacuum pyrolysis results where the interconversion of carbene and alkyne leads to the scrambling of labels over both alkynyl (sp) carbons

The Benzylidenecarbene–Phenylacetylene Rearrangement: An Experimental and Computational Study

Benzylidenecarbene was generated from a new photochemical source, 1-benzylidene-1a,9b-dihydro-1<i>H</i>-cyclopropa­[<i>l</i>]­phenanthrene, in deuterated benzene at ambient temperature. The carbene undergoes a facile rearrangement to phenylacetylene and could not be trapped by olefins. Generation of the carbene bearing a ¹³C label at the β-carbon produced phenylacetylene in which the label was found exclusively at the carbon adjacent to the phenyl ring. This overwhelming preference for H shift is consistent with B3LYP and CCSD­(T) calculations. The label distribution observed in this work, however, contrasts previously reported high-temperature flash vacuum pyrolysis results where the interconversion of carbene and alkyne leads to the scrambling of labels over both alkynyl (sp) carbons

The Benzylidenecarbene–Phenylacetylene Rearrangement: An Experimental and Computational Study

Benzylidenecarbene was generated from a new photochemical source, 1-benzylidene-1a,9b-dihydro-1<i>H</i>-cyclopropa­[<i>l</i>]­phenanthrene, in deuterated benzene at ambient temperature. The carbene undergoes a facile rearrangement to phenylacetylene and could not be trapped by olefins. Generation of the carbene bearing a ¹³C label at the β-carbon produced phenylacetylene in which the label was found exclusively at the carbon adjacent to the phenyl ring. This overwhelming preference for H shift is consistent with B3LYP and CCSD­(T) calculations. The label distribution observed in this work, however, contrasts previously reported high-temperature flash vacuum pyrolysis results where the interconversion of carbene and alkyne leads to the scrambling of labels over both alkynyl (sp) carbons