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- Amorín, R. O., et al.
(författare)
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Ubiquitous broad-line emission and the relation between ionized gas outflows and Lyman continuum escape in Green Pea galaxies
- 2024
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Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 682
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Tidskriftsartikel (refereegranskat)abstract
- We report observational evidence of highly turbulent ionized gas kinematics in a sample of 20 Lyman continuum (LyC) emitters (LCEs) at low redshift (z ∼ 0.3). Detailed Gaussian modeling of optical emission line profiles in high-dispersion spectra consistently shows that both bright recombination and collisionally excited lines can be fitted as one or two narrow components with intrinsic velocity dispersion of σ ∼ 40 − 100 km s−1, in addition to a broader component with σ ∼ 100 − 300 km s−1, which contributes up to ∼40% of the total flux and is preferentially blueshifted from the systemic velocity. We interpret the narrow emission as highly ionized gas close to the young massive star clusters and the broader emission as a signpost of unresolved ionized outflows, resulting from massive stars and supernova feedback. We find a significant correlation between the width of the broad emission and the LyC escape fraction, with strong LCEs exhibiting more complex and broader line profiles than galaxies with weaker or undetected LyC emission. We provide new observational evidence supporting predictions from models and simulations; our findings suggest that gas turbulence and outflows resulting from strong radiative and mechanical feedback play a key role in clearing channels through which LyC photons escape from galaxies. We propose that the detection of blueshifted broad emission in the nebular lines of compact extreme emission-line galaxies can provide a new indirect diagnostic of Lyman photon escape, which could be useful to identify potential LyC leakers in the epoch of reionization with the JWST.
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| 2. |
- Bertorello, AM, et al.
(författare)
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Analysis of Na+,K+-ATPase motion and incorporation into the plasma membrane in response to G protein-coupled receptor signals in living cells
- 2003
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Ingår i: Molecular biology of the cell. - : American Society for Cell Biology (ASCB). - 1059-1524 .- 1939-4586. ; 14:3, s. 1149-1157
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Tidskriftsartikel (refereegranskat)abstract
- Dopamine (DA) increases Na+,K+-ATPase activity in lung alveolar epithelial cells. This effect is associated with an increase in Na+,K+-ATPase molecules within the plasma membrane ( Ridge et al., 2002 ). Analysis of Na+,K+-ATPase motion was performed in real-time in alveolar cells stably expressing Na+,K+-ATPase molecules carrying a fluorescent tag (green fluorescent protein) in the α-subunit. The data demonstrate a distinct (random walk) pattern of basal movement of Na+,K+-ATPase–containing vesicles in nontreated cells. DA increased the directional movement (by 3.5 fold) of the vesicles and an increase in their velocity (by 25%) that consequently promoted the incorporation of vesicles into the plasma membrane. The movement of Na+,K+-ATPase–containing vesicles and incorporation into the plasma membrane were microtubule dependent, and disruption of this network perturbed vesicle motion toward the plasma membrane and prevented the increase in the Na+,K+-ATPase activity induced by DA. Thus, recruitment of new Na+,K+-ATPase molecules into the plasma membrane appears to be a major mechanism by which dopamine increases total cell Na+,K+-ATPase activity.
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| 3. |
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| 4. |
- Travin, Dmitrii Y., et al.
(författare)
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Biosynthesis of Translation Inhibitor Klebsazolicin Proceeds through Heterocyclization and N-Terminal Amidine Formation Catalyzed by a Single YcaO Enzyme
- 2018
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 140:16, s. 5625-5633
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Tidskriftsartikel (refereegranskat)abstract
- Klebsazolicin (KLB) is a recently discovered Klebsiella pneumonia peptide antibiotic targeting the exit tunnel of bacterial ribosome. KLB contains an N-terminal amidine ring and four azole heterocycles installed into a ribosomally synthesized precursor by dedicated maturation machinery. Using an in vitro system for KLB production, we show that the YcaO-domain KlpD maturation enzyme is a bifunctional cyclodehydratase required for the formation of both the core heterocycles and the N-terminal amidine ring. We further demonstrate that the amidine ring is formed concomitantly with proteolytic cleavage of azole-containing pro-KLB by a cellular protease TldD/E. Members of the YcaO family are diverse enzymes known to activate peptide carbonyls during natural product biosynthesis leading to the formation of azoline, macroamidine, and thioamide moieties. The ability of KlpD to simultaneously perform two distinct types of modifications is unprecedented for known YcaO proteins. The versatility of KlpD opens up possibilities for rational introduction of modifications into various peptide backbones.
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