| 121. |
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| 122. |
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| 123. |
- Dion, Claude, et al.
(författare)
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Optimally Controlled Field-Free Orientation of the Kicked Molecule
- 2005
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Ingår i: Physical Review A. ; 72, s. 023402-
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Tidskriftsartikel (refereegranskat)abstract
- Efficient and long-lived field-free molecular orientation is achieved using only two kicks appropriately delayed in time. The understanding of the mechanism rests upon a molecular target state providing the best efficiency versus persistence compromise. An optimal control scheme is referred to for fixing the free parameters (amplitudes and the time delay between them). The limited number of kicks, the robustness and the transposability to different molecular systems advocate in favor of the process, when considering its experimental feasibility.
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| 124. |
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| 125. |
- Frohlich, Michael W., et al.
(författare)
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Molecular phylogenetics of Euploca (Boraginaceae) : homoplasy in many characters, including the C-4 photosynthetic pathway
- 2022
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Ingår i: Botanical journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4074 .- 1095-8339. ; 199:2, s. 497-537
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Tidskriftsartikel (refereegranskat)abstract
- We present a phylogenetic analysis using plastid (matK, rbcL) and nuclear (nrITS) DNA for diverse Euploca spp. (formerly Heliotropium section Orthostachys) from the worldwide distribution of a genus and including species encompassing the wide physiological and morphological diversity of the genus. Our results indicate that some remarkably complex features arose multiple times in parallel in Euploca, including attributes of its subsections under section Orthostachys, notably plants that, above ground, consist almost entirely of inflorescences. To elucidate in greater detail the distribution of C-4 species in Euploca and Heliotropium s.s., we made > 800 delta C-13 determinations, including some from the traditional genus Tournefortia. We greatly increase the number of proven C-4 species in Euploca, but found none outside Euploca. Of the tested Euploca spp., c. 28% are C-3 or intermediate in carbon fixation pathway. Our phylogenetic results indicate four parallel/convergent acquisitions of C-4 photosynthesis or fewer origins with subsequent loss in some species.
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| 126. |
- Gros-Louis, Francois, et al.
(författare)
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Chromogranin B P413L variant as risk factor and modifier of disease onset for amyotrophic lateral sclerosis
- 2009
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 106:51, s. 21777-21782
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Tidskriftsartikel (refereegranskat)abstract
- Recently, chromogranins were reported to interact specifically with mutant forms of superoxide dismutase that are linked to amyotrophic lateral sclerosis (ALS). This interaction led us to analyze the frequencies of sequence variants of the CHGB gene in ALS patients and matched controls from three different countries. Of particular interest was the finding of the P413L CHGB variant present in 10% of ALS patients (n = 705) as compared to 4.5% in controls (n = 751), conferring a 2.2-fold greater relative risk to develop the disease (P < 0.0001). This effect was mainly contributed by the samples of French origin that yielded a frequency of the P413L variation at 17% in ALS (n = 289) and 5% in controls (n = 448), conferring a 3.3-fold greater risk to develop ALS. Furthermore, the P413L CHGB variant is associated with an earlier age of onset by almost a decade in both sporadic ALS and familial ALS cases. Genetic variation influencing age of onset in ALS had not previously been reported. Expression of fusion CHGB-EGFP constructs in SHSY-5Y cells revealed that the P413L variation can cause defective sorting of CHGB into secretory granules. The finding that CHGB may act as a susceptibility gene and modifier of onset in ALS is consistent with the emerging view that dysfunction of the secretory pathway may contribute to increased vulnerability of motor neurons.
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| 127. |
- Langreth, D. C., et al.
(författare)
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A density functional for sparse matter
- 2009
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Ingår i: Journal of Physics Condensed Matter. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 21:8, s. 084203-
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Tidskriftsartikel (refereegranskat)abstract
- Sparse matter is abundant and has both strong local bonds and weak nonbonding forces, in particular nonlocal van der Waals (vdW) forces between atoms separated by empty space. It encompasses a broad spectrum of systems, like soft matter, adsorption systems and biostructures. Density-functional theory (DFT), long since proven successful for dense matter, seems now to have come to a point, where useful extensions to sparse matter are available. In particular, a functional form, vdW-DF (Dion et al 2004 Phys. Rev. Lett. 92 246401; Thonhauser et al 2007 Phys. Rev. B 76 125112), has been proposed for the nonlocal correlations between electrons and applied to various relevant molecules and materials, including to those layered systems like graphite, boron nitride and molybdenum sulfide, to dimers of benzene, polycyclic aromatic hydrocarbons (PAHs), doped benzene, cytosine and DNA base pairs, to nonbonding forces in molecules, to adsorbed molecules, like benzene, naphthalene, phenol and adenine on graphite, alumina and metals, to polymer and carbon nanotube (CNT) crystals, and hydrogen storage in graphite and metal–organic frameworks (MOFs), and to the structure of DNA and of DNA with intercalators. Comparison with results from wavefunction calculations for the smaller systems and with experimental data for the extended ones show the vdW-DF path to be promising. This could have great ramifications.
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| 128. |
- Marsit, Souhir, et al.
(författare)
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Did Mitochondria Kill the Frog?
- 2018
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Ingår i: Developmental Cell. - : Elsevier BV. - 1534-5807 .- 1878-1551. ; 44:5, s. 539-541
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Genomic divergence can cause reproductive isolation between species. The molecular mechanisms underlying reproductive isolation can thus reveal which genomic features evolve rapidly and become unstable or incompatible in hybrids. In a recent paper in Nature, Gibeaux et al. (2018) report paternal genome instability and metabolic imbalance in hybrids between frog species.
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| 129. |
- McGurk, Michael P., et al.
(författare)
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Rapid evolution at the Drosophila telomere : transposable element dynamics at an intrinsically unstable locus
- 2021
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Ingår i: Genetics. - : Oxford University Press. - 0016-6731 .- 1943-2631. ; 217:2
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Tidskriftsartikel (refereegranskat)abstract
- Drosophila telomeres have been maintained by three families of active transposable elements (TEs), HeT-A, TAHRE, and TART, collectively referred to as HTTs, for tens of millions of years, which contrasts with an unusually high degree of HTT interspecific variation. While the impacts of conflict and domestication are often invoked to explain HTT variation, the telomeres are unstable structures such that neutral mutational processes and evolutionary tradeoffs may also drive HTT evolution. We leveraged population genomic data to analyze nearly 10,000 HTT insertions in 85 Drosophila melanogaster genomes and compared their variation to other more typical TE families. We observe that occasional large-scale copy number expansions of both HTTs and other TE families occur, highlighting that the HTTs are, like their feral cousins, typically repressed but primed to take over given the opportunity. However, large expansions of HTTs are not caused by the runaway activity of any particular HTT subfamilies or even associated with telomere-specific TE activity, as might be expected if HTTs are in strong genetic conflict with their hosts. Rather than conflict, we instead suggest that distinctive aspects of HTT copy number variation and sequence diversity largely reflect telomere instability, with HTT insertions being lost at much higher rates than other TEs elsewhere in the genome. We extend previous observations that telomere deletions occur at a high rate, and surprisingly discover that more than one-third do not appear to have been healed with an HTT insertion. We also report that some HTT families may be preferentially activated by the erosion of whole telomeres, implying the existence of HTT-specific host control mechanisms. We further suggest that the persistent telomere localization of HTTs may reflect a highly successful evolutionary strategy that trades away a stable insertion site in order to have reduced impact on the host genome. We propose that HTT evolution is driven by multiple processes, with niche specialization and telomere instability being previously underappreciated and likely predominant.
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| 130. |
- Oster, S K, et al.
(författare)
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Myc is an essential negative regulator of platelet-derived growth factor beta receptor expression.
- 2000
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Ingår i: Molecular and cellular biology. - 0270-7306. ; 20:18, s. 6768-78
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Tidskriftsartikel (refereegranskat)abstract
- Platelet-derived growth factor BB (PDGF BB) is a potent mitogen for fibroblasts as well as many other cell types. Interaction of PDGF BB with the PDGF beta receptor (PDGF-betaR) activates numerous signaling pathways and leads to a decrease in receptor expression on the cell surface. PDGF-betaR downregulation is effected at two levels, the immediate internalization of ligand-receptor complexes and the reduction in pdgf-betar mRNA expression. Our studies show that pdgf-betar mRNA suppression is regulated by the c-myc proto-oncogene. Both constitutive and inducible ectopic Myc protein can suppress pdgf-betar mRNA and protein. Suppression of pdgf-betar mRNA in response to Myc is specific, since expression of the related receptor pdgf-alphar is not affected. We further show that Myc suppresses pdgf-betar mRNA expression by a mechanism which is distinguishable from Myc autosuppression. Analysis of c-Myc-null fibroblasts demonstrates that Myc is required for the repression of pdgf-betar mRNA expression in quiescent fibroblasts following mitogen stimulation. In addition, it is evident that the Myc-mediated repression of pdgf-betar mRNA levels plays an important role in the regulation of basal pdgf-betar expression in proliferating cells. Thus, our studies suggest an essential role for Myc in a negative-feedback loop regulating the expression of the PDGF-betaR.
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