Nanoimprint Lithography–Based Fabrication of Plasmonic Array of Elliptical Nanoholes for Dual-Wavelength,Dual-Polarisation Refractive Index Sensing

Plasmonics - We report on the novel fabrication and characterisation of plasmonic arrays of elliptical nanohole, and their use for refractive index based sensing. The substrates were fabricated...     

National outbreak of Salmonella serotype saintpaul infections: importance of Texas restaurant investigations in implicating jalapeño peppers

Background

In May 2008, PulseNet detected a multistate outbreak of Salmonella enterica serotype Saintpaul infections. Initial investigations identified an epidemiologic association between illness and consumption of raw tomatoes, yet cases continued. In mid-June, we investigated two clusters of outbreak strain infections in Texas among patrons of Restaurant A and two establishments of Restaurant Chain B to determine the outbreak''s source.

Methodology/Principal Findings

We conducted independent case-control studies of Restaurant A and B patrons. Patients were matched to well controls by meal date. We conducted restaurant environmental investigations and traced the origin of implicated products. Forty-seven case-patients and 40 controls were enrolled in the Restaurant A study. Thirty case-patients and 31 controls were enrolled in the Restaurant Chain B study. In both studies, illness was independently associated with only one menu item, fresh salsa (Restaurant A: matched odds ratio [mOR], 37; 95% confidence interval [CI], 7.2–386; Restaurant B: mOR, 13; 95% CI 1.3–infinity). The only ingredient in common between the two salsas was raw jalapeño peppers. Cultures of jalapeño peppers collected from an importer that supplied Restaurant Chain B and serrano peppers and irrigation water from a Mexican farm that supplied that importer with jalapeño and serrano peppers grew the outbreak strain.

Conclusions/Significance

Jalapeño peppers, contaminated before arrival at the restaurants and served in uncooked fresh salsas, were the source of these infections. Our investigations, critical in understanding the broader multistate outbreak, exemplify an effective approach to investigating large foodborne outbreaks. Additional measures are needed to reduce produce contamination.     

Determination of the new anthelmintic monepantel and its sulfone metabolite in milk and muscle using a UHPLC-MS/MS and QuEChERS method

This is the first paper to report a method for the detection of the new anthelmintic monepantel and its sulfone metabolite in goat's milk and ovine muscle. Samples were extracted and purified using a modified QuEChERS method. A concentration step was included when analyzing in the low μg kg(-1) range. Analysis was carried out by ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in a 13min run time using atmospheric pressure electrospray ionisation in the negative mode (ESI(-)) and multiple reaction monitoring (MRM) scanning. Monepantel (m/z 472) and monepantel-sulfone (m/z 504) both had product ions at m/z 186 and m/z 166. The method has been single-laboratory validated according to the 2002/657/EC guidelines. The mean recovery in milk was 108 and 106% for monepantel and monepantel-sulfone, respectively. The mean recovery in muscle was 109 and 108% for monepantel and monepantel-sulfone, respectively. The coefficients of variation for the within laboratory repeatability and reproducibility were ≤6.4% in milk and ≤14.2% in muscle. The decision limits (CCα) in milk were 2.20 and 2.08 μg kg(-1) for monepantel and monepantel-sulfone, respectively. The decision limits (CCα) in muscle were 771 and 746 μg kg(-1) for monepantel and monepantel-sulfone, respectively.     

Protein Domains and Residues Involved in the CheZ/CheAS Interaction

CheZ localizes to chemoreceptor patches by binding CheA-short (CheA_S). Residues 70 to 134 of CheZ, constituting the apical loops and part of the dimerization domain, suffice for localization. Replacements of Tyr-118, Ile-119, Leu-123, Arg-124, and Leu-126 of CheA interfere with localization. These residues are exposed in the ′P1 domain of CheA_S.CheZ is the phosphorylated CheY (CheY-P) phosphatase of Escherichia coli (5) and a number of other gram-negative bacteria (2, 3). E. coli CheZ forms a homodimer that binds two molecules of CheY-P (Fig. ​(Fig.1A)1A) (20). Within each subunit, there is an N-terminal helix of about 30 residues that is involved in negative control of phosphatase activity (16). As CheZ is depicted in Fig. ​Fig.1,1, following this helix are a sharp turn, an extended ascending helix, a hairpin loop, and an extended descending helix. The Gln-147 residues at the active sites are in the middle of the extended helical region. Following the descending helix, there is an unstructured flexible connector to the short C-terminal helix that constitutes a CheY-P binding site.Open in a separate windowFIG. 1.Regions of CheZ and CheA_S required for localization of CheZ to receptor patches. (A) A backbone trace of CheZ from the CheZ-CheY cocrystal (20) is shown. Residues Try-97 and Phe-98, mutations of which specifically inhibit CheZ-GFP localization, are shown in blue. The portion of CheZ shown in red is not sufficient to localize CheZ-GFP fusions to receptor patches. The addition of the portion of CheZ shown in green enables the CheZ-GFP fusion protein to localize to receptor patches. The disconnected helices represent the peptides that bind CheY-P and present it to the active site. (B) Backbone trace of the Salmonella CheA P1 crystal structure (12). The images shown were created from the coordinates provided in the Protein Data Bank entry for identification number 1I5N by using RasTop. The part of the P1 domain retained in ′P1 is shown in cyan. The residue at the site of phosphorylation, His-48, is shown in green. Ala or Ser substitutions for Leu-123 and Leu-126 (shown in red) strongly inhibit CheZ-GFP localization, whereas an Ala or Ser substitution for Ile-119 (shown in yellow) and the Ser substitution for Phe-118 (also yellow) moderately affect localization.Shortly above the active sites, the two hairpin loops splay out from each other. The Trp-97 and Phe-98 residues that are important for localization but not for dimerization or activity (3, 19) are located near the apical loops of CheZ. Ser substitutions for hydrophobic residues Trp-94 through Val-121 block localization but also interfere with chemotaxis (3), perhaps because they interfere with dimer formation.A short form of the CheA kinase (CheA_S) (7) begins with Met-98 of the long form of CheA (CheA_L). CheA_S is produced in a 1:2 ratio relative to CheA_L (17) and is required for the localization of CheZ to the receptor patch. CheA_S is not essential for normal chemotaxis, as assessed in standard laboratory assays (15). However, both theoretical calculations (9, 10) and in vivo measurements (19) indicate that cells that fail to localize CheZ have very different intracellular distributions of CheY-P than wild-type cells. CheZ-localizing strains show a very abrupt decline in the CheY-P concentration near the receptor patch and rather uniform levels throughout the rest of the cell. Cells in which CheZ does not localize show a gradual decline in the CheY-P concentration with distance from the receptor patch, so that CheY-P concentrations vary throughout the cell.     

Estimates of milk constituents from lactating bonnet macaque (Macaca radiata) mothers between two and seven months post‐partum

Background The literature regarding milk composition in non‐human primates collected across offspring development is limited. We assayed milk samples from bonnet macaque (Macaca radiata) mothers as part of studies characterizing development of this species. Methods Milk was obtained when possible longitudinally from seven lactating bonnet macaque mothers. Samples were frozen until analysis. Individual samples were analyzed to determine the concentrations of electrolytes including sodium, potassium, calcium, chloride, and magnesium, as well as urea, protein, lipids, glucose, and lactose. Results A trend for increased lipids as well as protein percentage was noted with increasing infant age. Chloride and calcium showed an increase with age, whereas other electrolytes remained relatively stable across development. Conclusions The composition of the milk of this particular macaque species was similar to other Old World primates as well as humans. These data add to the limited information available on milk constituents among mammals.     

Mapping of the gene for endo-β-1,3-1,4-glucanase of Bacillus subtilis

Abstract An integrating plasmid has been used to mutagenise the gene coding for endo-β-1,3-1,4-glucanase of Bacillus subtilis . The gene, named bgl , has been mapped by PBS-1 transduction to the sacA-pureA region of the B. subtilis chromosome and is closely linked to the hutP 1 locus. The order of markers in this region is sacA 321- thiC 5- bgl - hutP 1- purA 16.