The RNA polymerase II (Pol II) elongation rate influences poly(A) site selection, with slow and fast Pol II derivatives causing upstream and downstream shifts, respectively, in poly(A) site utilization. In yeast, depletion of either of the histone chaperones FACT or Spt6 causes an upstream shift of poly(A) site use that strongly resembles the poly(A) profiles of slow Pol II mutant strains. Like slow Pol II mutant strains, FACT- and Spt6-depleted cells exhibit Pol II processivity defects, indicating that both Spt6 and FACT stimulate the Pol II elongation rate. Poly(A) profiles of some genes show atypical downstream shifts; this subset of genes overlaps well for FACT- or Spt6-depleted strains but is different from the atypical genes in Pol II speed mutant strains. In contrast, depletion of histone H3 or H4 causes a downstream shift of poly(A) sites for most genes, indicating that nucleosomes inhibit the Pol II elongation rate in vivo. Thus, chromatin-based control of the Pol II elongation rate is a potential mechanism, distinct from direct effects on the cleavage/polyadenylation machinery, to regulate alternative polyadenylation in response to genetic or environmental changes.
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http://dx.doi.org/10.1073/pnas.2405827121 | DOI Listing |
Biochim Biophys Acta Mol Cell Biol Lipids
January 2025
Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, Canada.
The synthesis of n-3 and n-6 polyunsaturated acids (PUFAs) is associated with physiological functions in mammals, being catalyzed by Δ-5D and Δ-6D desaturases and elongases Elovl-2 and Elovl-5. In this context, we aimed to study the chief kinetic features of PUFA liver anabolism, looking upon (i) the time-dependency for the specific activity of Δ-6D, Δ-5D, Elovl2, Elovl2/5 and Elovl5, using n-3 and n-6 precursors between 0 and 240 min ex vivo in mouse liver.; and (ii) the specific activity-substrate (α-linolenic acid; ALA) concentration responses of Δ-6D in the absence and presence of linoleic acid (LA), arachidonic acid (ARA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), an enzyme regarded as the rate-limiting step in PUFA anabolism.
View Article and Find Full Text PDFBiophys J
January 2025
Department of Physics, Northeastern University, Boston, MA, 02115, USA. Electronic address:
Binuclear ruthenium complexes have been investigated for potential DNA-targeted therapeutic and diagnostic applications. Studies of DNA threading intercalation, in which DNA base pairs must be broken for intercalation, have revealed means of optimizing a model binuclear ruthenium complex to obtain reversible DNA-ligand assemblies with the desired properties of high affinity and slow kinetics. Here, we used single-molecule force spectroscopy to study a binuclear ruthenium complex with a longer semi-rigid linker relative to the model complex.
View Article and Find Full Text PDFMaterials (Basel)
January 2025
Faculty of Technology Novi Sad, University of Novi Sad, Bulevar Cara Lazara 1, 21000 Novi Sad, Serbia.
Herbal dust, a waste byproduct from filter-tea production, was annealed to form ash that can be incorporated into natural rubber as an eco-friendly filler. Three types of herbal dust ash (HDA), green tea, hibiscus, and lemon balm, were added at two different contents, 2.5 and 5 phr, into the rubber compound, while the content of carbon black, as a filler, was maintained at 50 phr in all samples.
View Article and Find Full Text PDFMaterials (Basel)
December 2024
School of Materials Science and Engineering, Taiyuan University of Science and Technology, Taiyuan 030024, China.
Damage mechanisms are a key factor in materials science and are essential for understanding and predicting the behavior of materials under complex loading conditions. In this paper, the influence of different directions, different rates and different model parameters on the mechanical behavior of AZ31 magnesium alloy during the tensile process is investigated based on the secondary development of the VUMAT user subroutine based on the GTN damage model and verified by the tensile experiments at different loading rates and in different directions. The results show that AZ31 magnesium alloy exhibits significant differences in mechanical properties in radial and axial stretching, where the yield strength is lower in the radial direction than in the axial direction, and the elongation is the opposite.
View Article and Find Full Text PDFMaterials (Basel)
December 2024
COMTES FHT a.s., Prumyslova 995, 334 41 Dobrany, Czech Republic.
One of the concepts behind Generation IV reactors is a molten salt coolant system, where the materials for the reactor itself and for the primary and secondary circuit components are subjected to extreme chemical and thermal stresses. Due to the unavailability of these materials, a nickel-molybdenum alloy known as MoNiCr has been developed in the Czech Republic. This paper discusses the manufacturing process for the MoNiCr alloy, covering conventional casting technology, forming, powder atomization, additive manufacturing (AM) using the directed energy deposition (DED-LB) process, and final heat treatment.
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