AEG [N-(<i>2</i>-aminoethyl)glycine] is a small molecule which when polymerized can form a peptide nucleic acid backbone.

<p>A, The AEG monomer. B, its proposed role as a peptide nucleic acid showing three AEG molecules each connected to a base by an acetyl linkage. C, Predicted fragmentation pattern of AQC derivatized AEG (<i>m/z</i> 459) following collision-induced dissociation to produce daughter ions of <i>m/z</i> 171, 214, 289 and 119. Predicted structures were produced using High Chem Mass Frontier 5.1 software (High Chem Ltd., Slovak Republic).</p

Occurrence of N-(<i>2</i>-aminoethyl)glycine in axenic and environmental cyanobacterial samples.

<p>ND =  not detected; FW =  fresh water; Terr =  terrestrial; MW =  marine water; # =  hydrolyzed TCA extract; * =  total AEG free + bound; ?Info from PCC; “Na0H hydrolysis; a =  quantification from Stockholm University; Morphological Sections from Ref 12.</p

Quantification of BMAA in diatoms.

<p>Mean of BMAA concentration (±STD) in different samples of diatoms.</p><p><i>n</i>: Biological replicates.</p

Germanium dioxide treated and non-treated field samples.

<p>Mean of BMAA concentration (±STD) in different samples of diatoms.</p><p><i>n</i>: Biological replicates.</p

BMAA in axenic diatom cultures.

<p>¹ Culture Collection of Algae and Protozoa.</p><p>D: Detected.</p><p><i>n</i>: Biological replicates.</p

LC-MS/MS chromatograms of (a) BMAA and its isomer standards (5 µg L^–1 for BAMA, BMAA, and AEG and 20 µg L^–1 for DAB), and chromatograms showing BMAA produced by axenic cultures of diatoms; (b) <i>Achnanthes</i> sp. CCAP 1095/1; (c) <i>Navicula pelliculosa</i> CCAP 1050/9; (d) <i>Skeletonema marinoi</i> SAAAE 08603; (e) <i>Skeletonema marinoi</i> ST28; (f) <i>Thalassiosira</i> sp. CCAP 1085/15; (g) <i>Proboscia inermis</i> CCAP 1064.

<p>LC-MS/MS chromatograms of (a) BMAA and its isomer standards (5 µg L^–1 for BAMA, BMAA, and AEG and 20 µg L^–1 for DAB), and chromatograms showing BMAA produced by axenic cultures of diatoms; (b) <i>Achnanthes</i> sp. CCAP 1095/1; (c) <i>Navicula pelliculosa</i> CCAP 1050/9; (d) <i>Skeletonema marinoi</i> SAAAE 08603; (e) <i>Skeletonema marinoi</i> ST28; (f) <i>Thalassiosira</i> sp. CCAP 1085/15; (g) <i>Proboscia inermis</i> CCAP 1064.</p

Host cell-derived lactate functions as an effector molecule in <i>Neisseria meningitidis</i> microcolony dispersal

<div><p>The development of meningococcal disease, caused by the human pathogen <i>Neisseria meningitidis</i>, is preceded by the colonization of the epithelial layer in the nasopharynx. After initial adhesion to host cells meningococci form aggregates, through pilus-pilus interactions, termed microcolonies from which the bacteria later detach. Dispersal from microcolonies enables access to new colonization sites and facilitates the crossing of the cell barrier; however, this process is poorly understood. In this study, we used live-cell imaging to investigate the process of <i>N</i>. <i>meningitidis</i> microcolony dispersal. We show that direct contact with host cells is not required for microcolony dispersal, instead accumulation of a host-derived effector molecule induces microcolony dispersal. By using a host-cell free approach, we demonstrated that lactate, secreted from host cells, initiate rapid dispersal of microcolonies. Interestingly, metabolic utilization of lactate by the bacteria was not required for induction of dispersal, suggesting that lactate plays a role as a signaling molecule. Furthermore, <i>Neisseria gonorrhoeae</i> microcolony dispersal could also be induced by lactate. These findings reveal a role of host-secreted lactate in microcolony dispersal and virulence of pathogenic <i>Neisseria</i>.</p></div

Lactate-induced microcolony dispersal is not dependent on metabolic utilization by <i>N</i>. <i>meningitidis</i>.

<p>Growth of FAM20 wild-type and its isogenic mutants Δ<i>lctP</i>, Δ<i>ldhA</i> Δ<i>ldhD</i>, Δ<i>lldA</i> in the presence of glucose (A), L-lactate (B) or D-lactate (C) as the major carbon source. (D-G) The timing of microcolony dispersal was examined after addition of DMEM (control), CM, L-lactate (10 mM) or D-lactate (10 mM) to preformed Δ<i>lctP</i> (D), Δ<i>ldhD</i> (E), Δ<i>ldhA</i> (F) or Δ<i>lldA</i> (G) microcolonies. Induction is represented by a black horizontal line. For panel A-C, one representative growth curve out of two is shown. For panel D-G, data represent the mean ± SD of three independent experiments. ^*p < 0.05. ns, non-significant.</p

Lactate induces microcolony dispersal in <i>N</i>. <i>meningitidis</i> strain JB515 and <i>N</i>. <i>gonorrhoeae</i> strain MS11.

<p>(A) Bacteria (10⁷ CFU/ml) were allowed to form microcolonies for 3 h (black horizontal line) before addition of DMEM supplemented with lactate at final concentrations ranging from 0.5–10 mM. Microcolony dispersal was examined by live-cell microscopy for 8 h. Data represent the mean ± SD of three independent experiments. ^*p < 0.05. (B) Representative images showing dispersal 40 min, 60 min and 80 min after addition of lactate (1 mM) to JB515 and MS11 microcolonies. Scale bar, 20 μm.</p

Cell-conditioned medium (CM) induces the dispersal of microcolonies.

<p>(A) Schematic drawing of the experimental set-up. Confluent FaDu cells were washed and incubated with DMEM. After 5 h, the CM was collected, sterile filtered, and added at a 1:1 volume ratio to bacterial meningococcal suspensions where microcolonies had been allowed to form for 3 h (initial bacterial concentration of 10⁷ CFU/ml). A black horizontal line in panels B and D represents the 3 h time point. Bacteria were observed by live-cell time-lapse microscopy. DMEM was used as a control. (B) Microcolony dispersal upon addition of CM from infected (+) or uninfected (-) cells to FAM20 bacteria in liquid. (C) Microcolony dispersal was examined by live-cell time-lapse microscopy after addition of CM. Representative images are shown 10, 20 and 30 min after induction. Scale bar, 10 μm. (D) Microcolony dispersal upon addition of CM collected from FaDu cells after 5, 15, and 30 min and 1 h and 5 h. (E) Microcolony dispersal of FAM20 resuspended (10⁷ CFU/ml) in either CM or DMEM (control) when the incubation was initiated. Data represent the mean ± SD of three independent experiments. ^*p < 0.05. ns, non-significant.</p