| 1. |
- Barbosa, Simone C., et al.
(författare)
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The Importance of Cyclic Structure for Labaditin on Its Antimicrobial Activity Against Staphylococcus aureus
- 2016
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Ingår i: Colloids and Surfaces B. - : Elsevier BV. - 0927-7765 .- 1873-4367. ; 148, s. 453-459
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Tidskriftsartikel (refereegranskat)abstract
- Antimicrobial resistance has reached alarming levels in many countries, thus leading to a search for new classes of antibiotics, such as antimicrobial peptides whose activity is exerted by interacting specifically with the microorganism membrane. In this study, we investigate the molecular-level mechanism of action for Labaditin (Lo), a 10-amino acid residue cyclic peptide from Jatropha multifida with known bactericidal activity againstStreptococcus mutans. We show that Lo is also effective against Staphylococcus aureus(S. aureus) but this does not apply to its linear analogue (L1). Using polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS), we observed with that the secondary structure of Lo was preserved upon interacting with Langmuir monolayers from a phospholipid mixture mimicking S. aureus membrane, in contrast to L1. This structure preservation for the rigid, cyclic Lo is key for the self-assembly of peptide nanotubes that induce pore formation in large unilamellar vesicles (LUVs), according to permeability assays and dynamic light scattering measurements. In summary, the comparison between Labaditin (Lo) and its linear analogue L1 allowed us to infer that the bactericidal activity of Lo is more related to its interaction with the membrane. It does not require specific metabolic targets, which makes cyclic peptides promising for antibiotics without bacteria resistance.
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| 2. |
- Freitas, André Victor Lucci, et al.
(författare)
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'Species' from two different butterfly genera combined into one : Description of a new genus of Euptychiina (Nymphalidae: Satyrinae) with unusually variable wing pattern
- 2016
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Ingår i: Revista Brasileira de Entomologia. - : FapUNIFESP (SciELO). - 0085-5626. ; 60:2, s. 157-165
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Tidskriftsartikel (refereegranskat)abstract
- Sepona Freitas and Barbosa, gen. nov. is proposed for the Neotropical satyrine butterfly species Euptychia punctata Weymer, 1911 and its junior subjective synonyms Euptychia griseola Weymer, 1911 and Taygetis indecisa Ribeiro, 1931. The new genus has a distinctive wing pattern and shape of the valvae in the male genitalia, the latter being a unique autapomorphy within the subtribe Euptychiina. Based on molecular data, this genus is not sister to any other single euptychiine genus, instead appearing as the sister to all remaining genera in the Taygetis clade. The present paper illustrates the complexity of the taxonomy of Euptychiina, and the importance of using different sources of evidence in taxonomic studies.
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| 3. |
- Terjesen, Siri, et al.
(författare)
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Does the presence of independent and female directors impact firm performance? A multi-country study of board diversity
- 2016
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Ingår i: Journal of Management and Governance. - : Springer Science and Business Media LLC. - 1385-3457 .- 1572-963X. ; 20:3, s. 447-483
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Tidskriftsartikel (refereegranskat)abstract
- This study empirically analyzes whether gender diversity enhances boards of directors’ independence and efficiency. Using data from 3,876 public firms in 47 countries and controlling for a wide set of corporate governance mechanisms, we find that firms with more female directors have higher firm performance by market (Tobin’s Q) and accounting (return on assets) measures. The results also suggest that external independent directors do not contribute to firm performance unless the board is gender diversified. These results hold with respect to different estimation models and robustness tests. Overall, our findings provide evidence that the female directors enhance boards of directors’ effectiveness. Finally, we find that firms that are concerned with board independence, and that firms in more complex environments are more likely to have gender-balanced boards.
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