Beitrag zur Frage der Stickstoffassimilation durch den Bacillus ellenbachensis α Caron

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Symmetric advantage? Ballot type, gender, and facial attractiveness in the Mexican Chamber of Deputies

Some research suggests that candidates with a "pretty face" may have an electoral advantage, but it is less clear whether this advantage is due to the information shortcut taken by low-information voters, or whether it is due to deeper cognitive preferences that apply equally in low- and high-information voters. Mexico's Chamber of Deputies, which elects 300 members from single-member plurality districts and 200 members from political parties (based on the results of a closed-list proportional representation votes), offers a natural experiment to test this effect. We analyze photographs of the members of the 2015-2018 Mexican Chamber of Deputies to calculate facial symmetry, and while we fail to find a significant difference for male candidates, female candidates are judged based on their appearance, as SMD females have more symmetric features and PR females less symmetric ones than their male colleagues.Political Scienc

Bakteriologische Untersuchungen über die Einwirkung Saurer Jodkaliwasserstoffsuperoxydmischungen auf Bakterien

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Regulation of nitrogenase-2 in Azotobacter vinelandii by ammonium, molybdenum, and vanadium.

Under diazotrophic conditions in the absence of molybdenum and in the presence of vanadium, Azotobacter vinelandii reduces N2 to NH4+ by using nitrogenase-2, a V-containing enzyme complex encoded by vnfH (the gene for dinitrogenase reductase-2), and vnfDGK (the genes for dinitrogenase-2 subunits). Accumulation of the vnfHorfFd and vnfDGK transcripts occurred under Mo-deficient conditions in the presence and absence of V; however, in the case of vnfDGK, the protein products only accumulated in the presence of V. This suggests that V is required for translation of the vnfDGK transcripts. In addition, expression of vnfH-lacZ and vnfD-lacZ transcriptional fusions was only partially repressed in the presence of NH4+. Transcripts hybridizing with vnfH (1.4 and 1.0 kb), vnfDG (3.4 and 1.8 kb), and vnfK (3.4 kb) were detected in RNA extracted from wild-type cells cultured with NH4+ in the presence or absence of V. However, nitrogenase-2 subunits were not detected in extracts of cells derepressed for nitrogenase-2 in the presence of NH4+. These results indicate that this nitrogen source acts at the posttranscriptional level as well as at the transcriptional level. vnf transcripts were not detected in the presence of Mo (with or without NH4+)

Wörterbuch der griechischen Sprache /

First pt. also has title: Griechisch-deutsches Wörterbuch zum Schul- und Privatgebrauch.1. T. Griechisch-deutsch.Mode of access: Internet

Phenotypic characterization of a tungsten-tolerant mutant of Azotobacter vinelandii.

A tungsten-tolerant mutant strain (CA6) of Azotobacter vinelandii first described in 1980 (P. E. Bishop, D. M. L. Jarlenski, and D. R. Hetherington, Proc. Natl. Acad. Sci. USA 77:7342-7346, 1980) has been further characterized. Results from growth experiments suggest that both nitrogenases 1 and 3 are utilized when CA6 grows in N-free medium containing Na2MoO4. Strain CA6.1.71, which lacks both nitrogenases 2 and 3, grew as well as strain CA in N-free medium containing Na2MoO4 after an initial lag. This indicates that nitrogenase 1 is fully functional in strain CA6. nifH-lacZ and anfH-lacZ transcriptional fusions were expressed in CA6 in the presence of Na2MoO4. Thus, in contrast to wild-type strain CA, transcription of the anfHDGK gene cluster in strain CA6 is not repressed by Mo. Expression of the vnfD-lacZ fusion was the same in both strains CA and CA6. In agreement with the results obtained with lac fusions, subunits of both nitrogenases 1 and 3 were found in protein extracts of CA6 cells grown in N-free medium containing Na2MoO4. However, CA6 cells, cultured in the presence of Na2WO4, accumulated nitrogenase 3 proteins without detectable amounts of nitrogenase 1 proteins. This indicates that expression of Mo-independent nitrogenase 3 is the basis for the tungsten tolerance phenotype of strain CA6. A measure of Mo accumulation as a function of time showed that accumulation by strain CA6 was slower than that for strain CA. When Mo accumulation was studied as a function of Na2MoO4 concentration, the two strains accumulated similar amounts of Mo in the concentration range of 0 to 1 microM Na2MoO4 during a 2-h period. Within the range of 1 to 5 microM Na2MoO4, Mo accumulation by strain CA increased linearly with increasing concentration whereas no further increases were observed for strain CA6. These results are consistent with the possibility that the tungsten tolerance mutation carried by CA6 is in a Mo transport system

It’s Critical: Student Attitudes toward Critical Thinking and an Assessment of a Lecture to an Introductory Engineering Class

Critical thinking is an essential skill for achievement as an engineering student and for success in the engineering profession. Critical thinking can be defined as a mental process to responsibly form an unbiased conclusion that includes identification, skillful analysis, and evaluation of evidence to guide decision-making. This article evaluates a research project undertaken by students at the University of San Diego. In the investigators’ work, they analyzed the definitions of critical thinking and bias, what tools could be used to help in the critical thinking process, and how concepts such as bias and critical thinking affect engineers in their occupations. The team then presented this information to several introductory engineering classes in the form of a lecture and asked the students to assess their knowledge and understanding of critical thinking concepts before and after the presentation. The investigators evaluated the surveys and discovered that most students improved their definitions of bias and critical thinking after the lecture. The students also generally improved their self-rating of understanding critical thinking concepts

Structural and computational studies of the Staphylococcus aureus sortase B-substrate complex reveal a substrate-stabilized oxyanion hole.

Sortase cysteine transpeptidases covalently attach proteins to the bacterial cell wall or assemble fiber-like pili that promote bacterial adhesion. Members of this enzyme superfamily are widely distributed in Gram-positive bacteria that frequently utilize multiple sortases to elaborate their peptidoglycan. Sortases catalyze transpeptidation using a conserved active site His-Cys-Arg triad that joins a sorting signal located at the C terminus of their protein substrate to an amino nucleophile located on the cell surface. However, despite extensive study, the catalytic mechanism and molecular basis of substrate recognition remains poorly understood. Here we report the crystal structure of the Staphylococcus aureus sortase B enzyme in a covalent complex with an analog of its NPQTN sorting signal substrate, revealing the structural basis through which it displays the IsdC protein involved in heme-iron scavenging from human hemoglobin. The results of computational modeling, molecular dynamics simulations, and targeted amino acid mutagenesis indicate that the backbone amide of Glu(224) and the side chain of Arg(233) form an oxyanion hole in sortase B that stabilizes high energy tetrahedral catalytic intermediates. Surprisingly, a highly conserved threonine residue within the bound sorting signal substrate facilitates construction of the oxyanion hole by stabilizing the position of the active site arginine residue via hydrogen bonding. Molecular dynamics simulations and primary sequence conservation suggest that the sorting signal-stabilized oxyanion hole is a universal feature of enzymes within the sortase superfamily