Joshua Lederberg (1925–2008)
Krishna Dronamraju in A Century of Geneticists, 2018
After a series of disappointing experiments to demonstrate transfer of genetic information by nucleic acid preparations, Ryan encouraged Josh to apply to the Department of Microbiology and Botany at Yale University to pursue a genetics project with bacteria under the direction of Edward L. Tatum, who had recently relocated from Stanford University. The original plan was for Josh to spend three to six months at Yale University and then return to Columbia’s Physicians and Surgeons Medical School. Within six weeks, using nutritional mutants of Escherichia coli K-12 that Tatum had prepared, Josh conducted experiments establishing that gene transfer occurred in bacteria (Zuckerman and Lederberg 1986). The initial reports in 1946 and 1947 were not universally accepted, it being argued by senior international authorities that the results could be attributed to exchange of released nutrients by the mutants, coupled with back mutation during the resulting limited growth. Max Zelle from Cornell University in Ithaca, New York, proposed that the issue be resolved by studies on single cells isolated by micromanipulation, a task that was not completed until 1950.
Chemical Synthesis of Core Structures
Helmut Brade, Steven M. Opal, Stefanie N. Vogel, David C. Morrison in Endotoxin in Health and Disease, 2020
For the unambiguous structural proof of the revised structure of the outer core of Escherichia coli K-12, containing one heptopyranosyl unit attached to a glucose residue of the outer core, the synthesis of the disaccharide l-α-d-Hepp-(l→6)-d-G1c was performed employing the trichloroacetimidate procedure (65). NMR and mass spectral data of the synthetic compound were identical with those of the natural derivative isolated from E. coli K-12 LPS. The synthetic scheme was further extended to include the neighboring glucose units (66). For the preparation of neoglycoconjugates, the heptopyranosyl derivatives of 3-O-kojibiosyl-glucose, i.e., l-α-d-Hepp-(l→6)-α-DGlcp-(1→2)-α-d-Glcp-(l→3)-α-d-Glcp and part structures thereof were prepared as the respective allyl glycosides (67).
Biocatalyzed Synthesis of Antidiabetic Drugs
Peter Grunwald in Pharmaceutical Biocatalysis, 2019
Remarkably, human insulin was the first animal protein to be produced in bacteria in a sequence identical to that of the human pancreatic peptide, as early as 1978 by Genentech (lab scale) and Eli Lilly and Co. (scale-up) (Johnson, 1983), working together to achieve expression of recombinant human insulin in Escherichia coli K-12 using genes for the insulin A and B chains; thus, each insulin chain was produced as a β-galactosidase fusion protein in separate fermentations using E. coli cells previously engineered with plasmids containing either the A or B insulin peptide sequence. The intracellular products, once removed from the inclusion bodies, were chemically cleavage by CNBr at the Met residue between the β-gal and the A or B chains, purified, suffered an oxidative sulfitolysis and chemically linked to afford crude insulin. A final purification process lead to the first production of recombinant human insulin, approved by drug regulatory agencies in 1982 (Ladisch and Kohlmann, 1992).
Thermostable xylanase inhibits and disassembles Pseudomonas aeruginosa biofilms
Published in Biofouling, 2018
Jin-Hyung Lee, Yong-Guy Kim, Jintae Lee
All experiments were conducted at 37°C in Luria-Bertani (LB, pH 7.0) broth, which was used to culture P. aeruginosa PAO1 (Holloway 1955), P. aeruginosa PA14 (Rahme et al. 1995), two methicillin-sensitive Staphylococcus aureus (MSSA; ATCC 25923 and ATCC 6538), and a methicillin-resistant Staphylococcus aureus (MRSA MW2, ATCC BAA-1707), two commensal Escherichia coli K-12 (MG1655, BW25113) and E. coli O157:H7 (ATCC 43895, also called EDL933) strains. To culture P. aeruginosa PAO1 (or PA14)/pMRP9-1 cells tagged with green fluorescent, LB broth containing 150 μg ml−1 of carbenicillin was used to maintain the pMRP9-1-GFP plasmid. Bacterial cells were initially streaked from –80°C glycerol stock on LB agar plates. After growth, cells were cultured from a fresh single colony in LB broth. Then, for phenotypic assays, overnight cultures (stationary phase cells) were inoculated again in LB broth at an initial turbidity of 0.05 at 600 nm. Alginate lyase, cellulase, glucanase, lipase, pectinase, and xylanase were purchased from Sigma-Aldrich (St Louis, MO, USA). The recombinant xylanase originally from Thermomyces lanuginosus was expressed in Aspergillus oryzae. All enzymes were dissolved in sterile water and the same amount of sterile water was used a negative control. For cell growth measurements, turbidity was measured at 600 nm using a spectrophotometer (Optizen 2120UV, Mecasys, Daejeon, Korea).
Multifunctional magnetite nanoparticles to enable delivery of siRNA for the potential treatment of Alzheimer’s
Published in Drug Delivery, 2020
Natalia Lopez-Barbosa, Juan G. Garcia, Javier Cifuentes, Lina M. Castro, Felipe Vargas, Carlos Ostos, Gloria P. Cardona-Gomez, Alher Mauricio Hernandez, Juan C. Cruz
Overexpression of OmpA protein in E. Coli was accomplished in accordance with the protocol by Gonzalez Barrios et al. (Aguilera Segura et al., 2014). Escherichia coli K-12 W3110/pCA24N OmpA + was cultured in LB agar plates containing yeast extract (5 g/L), bacto tryptone (10 g/L), NaCl (10 g/L) and chloramphenicol (50 μg/mL), overnight and at 37 °C. Further, inoculation of a colony was attained in LB medium with chloramphenicol (50 mL) and was incubated for 16 h at 37 °C, 250 rpm. In addition, a fresh LB medium (19.5 mL) was inoculated with the previous culture (500 μL) for 16 h at 37 °C, 250 rpm. Cultures were grown until reaching an optical density at 600 nm (OD600nm) of 0.7. At this point, isopropylthio-β-galactoside (IPTG, 95%, Sigma-Aldrich) (2 mM) was added to induce OmpA expression. IPTG exposure was performed for 3 h.
Modulation of cytokine/chemokine production in human macrophages by bisphenol A: A comparison to analogues and interactions with genistein
Published in Journal of Immunotoxicology, 2018
Yingjia Chen, Hannah Shibo Xu, Tai L. Guo
Suppression of cytokines/chemokines by BPA at 1 and 100 µM might help to explain how host defense in exposed individuals is compromised during bacterial and/or virus infection (Sugita-Konishi et al. 2003). Specifically, subcutaneous BPA exposure (5 mg/kg) diminished clearance of Escherichia coli K-12 from the peritoneal cavity of BALB/c mice within 24 h. These effects were accompanied by reductions in neutrophil phagocytic activity and by reductions in expected levels of macrophages and lymphocytes at infection foci. Another study noted that BPA exposure (perinatal, 5 μg/kg/day) of Wistar rats resulted in decreased numbers of T-cells and dendritic cells in the spleen and mesenteric lymph nodes, outcomes that contributed to an increased residence of Nippostrongylus brasiliensis following infection (Ménard et al. 2014).
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