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1268. Xylem growth cessation in stems and branches of European beech and silver birch : influences of temperature and droughtLorène Julia Marchand, Jožica Gričar, Peter Prislan, Inge Dox, Melanie S. Verlinden, Omar Flores, Matteo Campioli, 2025, original scientific article Abstract: Introduction: Assessing wood growth phenology over multiple years is essential for understanding the environmental drivers of forest growth and improving large-scale predictions of the carbon cycle. Xylogenesis methods facilitate the assessment of the timing and rate of xylem cell wall thickening, the primary sink of carbon in wood. In angiosperm trees, where wood anatomy is complex, significantly less is known about the factors controlling growth cessation in autumn due to indirect, sinteracting, and lag effects, in contrast to growth resumption in spring. Furthermore, both branch and stem growth must be considered to account for the total aboveground phenology. Methods: In this study, we focused on European beech (Fagus sylvatica) and silver birch (Betula pendula) in a mild temperate region (Northern Belgium). We examined the progress of cell wall thickening in autumn and the seasonal timing of xylem growth cessation for these species’ stems over five years and for their branches over one year in mature trees. In addition, we investigated the same variables in the stems and branches of potted saplings for two years and for oak (Quercus robur) and aspen (Populus tremula) saplings over one year. Results: Our results demonstrate a considerable variation in the progression and cessation of wood growth, with differences of up to a month and a half in growth cessation (early September to late October), predominantly driven by climatic variables. Early cessation of xylem growth in stems was strongly associated with high temperatures in April and August, elevated vapour pressure deficit, and severe soil drought in August. The progression of cell wall thickening in late summer was generally synchronized between branches and stems for every species. However, branches sustained a higher percentage of growth (approximately 2 weeks) in early autumn during non-drought years. Discussion: These findings provide valuable insights for refining models of forest growth and carbon storage, enabling a more comprehensive representation that encompasses the entire tree under different climatic scenarios.
Keywords: phenology, cambium, cell wall thickening, hardwood species, atmospheric drought
Published in DiRROS: 08.09.2025; Views: 325; Downloads: 159
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1270. Silver binding dichotomy for 7-deazaadenine/thymine : preference for Watson–Crick pairing over homobase interactions in DNACarmen López-Chamorro, Antonio Pérez-Romero, Alicia Domínguez-Martín, Uroš Javornik, Oscar Palacios, Janez Plavec, Miguel A. Galindo, 2025, original scientific article Abstract: DNA strands modified with 7-deazaadenine (X) and 7-deazaguanine (Y) have shown promise in forming silver-DNA assemblies while maintaining canonical Watson–Crick base pairing, highlighting the compatibility of silver binding with standard DNA structures. However, critical questions remain regarding the binding preferences of AgI ions to sequences containing 7-deazapurine bases, particularly the prevalence of silver-modified Watson–Crick base pairs versus alternative homobase pair arrangements. To address this, we examined the binding of AgI to complementary X-T sequences, demonstrating a strong preference for canonical X-AgI-T pairing over homoleptic X-AgI-X or T-AgI-T pairs. Additionally, we report the discovery of a novel metallized DNA duplex featuring continuous X-AgI-X homobase pairs, whose structural analysis at the monomeric level, using model base 9-propyl-7-deazaadenine (pX) and AgI salts, reveals a unique silver-binding pattern through the Watson–Crick face. These findings not only advance our understanding of silver-mediated DNA architectures using 7-deazapurines but also provide a foundation for the rational design of sophisticated metal-DNA nanostructures with tailored properties, opening new avenues for the development of functional DNA-based materials.
Keywords: crystal structure, genetics, ions, silver, solution chemistry
Published in DiRROS: 08.09.2025; Views: 410; Downloads: 173
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