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Selecting dominant or rare tree species as habitat trees: Consequences for epiphyte diversity in temperate mountain forests
No full textThe retention of habitat trees, defined as large old trees saved from logging, is a key strategy for biodiversity conservation in production forests. Epiphytic bryophytes and lichens, which rely on the diverse microhabitats provided by large old trees, are expected to benefit significantly from this practice. The selection of habitat trees has become mandatory in some governmental biodiversity conservation strategies. While broadleaved trees are known to support epiphytes, the role of forest stand characteristics remains less understood. This study investigates whether selecting habitat trees of a stand's dominant tree species or of rare accessory tree species is most effective to conserve a high species richness of epiphytic bryophytes and lichens using 132 study plots and 657 habitat trees in temperate mountain forest of southwestern Germany, representing beech, spruce, and spruce co-dominant forests. Tree species identity of the habitat tree had different effects on epiphyte diversity for different forest types. In beech forest, epiphyte species richness was increased if the habitat tree was also a beech tree; this relationship was primarily driven by bryophytes. In spruce forests and spruce co-dominant forests, epiphyte species richness was higher if rare accessory tree species were selected as habitat trees. This result may guide foresters during habitat tree selection, which has become an important issue at least in German forest management
Elderly male patient presenting with jaundice and cholangitis brings an unexpected histopathological finding, case report
No full textIn this report, we present a case of the first-time manifestation of Langerhans cell histiocytosis in the biliary tract of a 79-year-old male patient. Cholangiocarcinoma was the suspected diagnosis, based on the patient's painless jaundice. The postoperative histological findings revealed a primary, single-system, unifocal Langerhans cell histiocytosis of the biliary tract, without the patient having any other typical clinical manifestations, e.g., of the skin or lungs. Neither the primary manifestation nor the patient's age fully aligns with current knowledge of Langerhans cell histiocytosis
Phosphorylation‐dependent activation of the bHLH transcription factor ICE1/SCRM promotes polarization of the Arabidopsis zygote
No full textIn Arabidopsis thaliana, the asymmetric cell division (ACD) of the zygote gives rise to the embryo proper and an extraembryonic suspensor, respectively. This process is controlled by the ERECTA-YODA-MPK3/6 receptor kinase-MAP kinase-signaling pathway, which also orchestrates ACDs in the epidermis. In this context, the bHLH transcription factor ICE1/SCRM is negatively controlled by MPK3/6-directed phosphorylation. However, it is unknown whether this regulatory module is similarly involved in the zygotic ACD.We investigated the function of SCRM in zygote polarization by analyzing the effect of loss-of-function alleles and variants that cannot be phosphorylated by MPK3/6, protein accumulation, and target gene expression.Our results show that SCRM has a critical function in zygote polarization and acts in parallel with the known MPK3/6 target WRKY2 in activating WOX8. Our work further demonstrates that SCRM activity in the early embryo is positively controlled by MPK3/6-mediated phosphorylation.Therefore, the effect of MAP kinase-directed phosphorylation of the same target protein fundamentally differs between the embryo and the epidermis, shedding light on cell type-specific, differential gene regulation by common signaling pathways
Regulation of plant development through hormonal and transcriptional pathways: insights into female germline initiation and root meristem maintenance in Arabidopsis thaliana
No full textThe regulation of plant development is highly coordinated process governed by the intricate interplay of hormonal and transcriptional pathways, which regulate cell fate, organogenesis, and tissue maintenance. In Arabidopsis thaliana, these regulatory networks are essential for several developmental processes including germline initiation and root meristem maintenance, where precise spatial and temporal control of gene expression is critical. Hormones like auxin and cytokinin act as key signaling molecules, modulating downstream transcriptional programs through the activity of specific transcription factors and regulatory complexes. These pathways often function within tightly controlled feedback loops and cross-regulatory networks, ensuring robust developmental outcomes in response to both intrinsic genetic cues and external environmental stimuli. By dissecting the molecular mechanisms underlying these processes, this research provides novel insights into the regulation of plant development which acts as a foundation for targeted genetic interventions for agricultural improvement.Unlike animals, plants initiate their germline from somatic cells within reproductive organs. In Arabidopsis thaliana ovules, a single sub-epidermal cell in the nucellus differentiates into the megaspore mother cell (MMC), the progenitor of the female germline. This process involves distinct morphological and molecular changes, including increased cell and nuclear volume, callose deposition, H2A.Z histone variant deposition, and specific transcriptional reprogramming, ultimately leading to meiosis and the formation of the female gametophyte. While factors restricting germline fate to a single sub-epidermal cell have been identified, understanding the mechanisms conferring MMC identity remains a key focus. The first chapter of my thesis investigates the role of WINDHOSE1 (WIH1) and WIH2, annexin-VII-related proteins, in Arabidopsis megasporogenesis. Localized to the plasma membrane, WIH1 and WIH2 interact with RAB GTPASE HOMOLOG A1 (RABA1) GTPases, crucial components of trans-Golgi vesicles, to regulate polar PIN-FORMED 1 (PIN1) subcellular localization and auxin accumulation in cells neighboring the MMC. These findings reveal a novel non-cell-autonomous mechanism by which WIH1 and WIH2, acting through RABA1-mediated vesicular trafficking, influence spatial auxin response patterning, thereby contributing to germline initiation. The study underscores the importance of orchestrated cell-cell communication and auxin dynamics in establishing germ cell fate during plant reproduction. Stem cells in plant apical meristems are crucial for continuous organogenesis throughout a plant's lifespan. In roots, the quiescent center (QC) cells, characterized by WUSCHEL-RELATED HOMEOBOX 5 (WOX5) expression, maintain the stem cell niche. The second chapter of my thesis investigates the role of another WOX transcription factor, WOX9, in regulating root meristem size in Arabidopsis thaliana. Unlike stem cells, which divide infrequently, their proliferating daughter cells, known as transit amplifying cells (TACs), undergo active division to produce the bulk of new cells. In the proximal root meristem, TACs exit proliferation and begin differentiation at the transition zone (TZ), a process promoted by the phytohormone cytokinin (CK). Although elevated CK levels have long been known to inhibit root growth, the mechanisms maintaining CK homeostasis remained elusive. This research uncovers a novel regulatory mechanism where WOX9 plays a critical role in vasculature cells of the TZ to sustain TAC proliferation and maintain meristem activity. Mechanistically, WOX9 interacts with the homeodomain leucine zipper III (HD-ZIPIII) transcription factors PHABULOSA (PHB) and PHAVOLUTA (PHV), attenuating their ability to activate the CK biosynthetic gene ISOPENTENYLTRANSFERASE 7 (IPT7). This interaction dampens CK biosynthesis, preventing premature proliferation exit of TACs and ensuring sustained meristem activity. These findings provide new insights into mechanisms fine-tuning CK levels in root development, contributing to our understanding of plant stem cell regulation and meristem maintenance
Algorithm-based analysis of lymph node dissection strategies and survival outcomes in primary oral squamous cell carcinoma
No full textIntroduction: Recent advancements in treatment approaches for oral squamous cell carcinomas (OSCCs) necessitate a reevaluation of neck dissection techniques and their impact on patient outcomes and morbidity.Methods: This retrospective study of 250 OSCC patients recruited between 2017–2022 examined the association between neck dissection techniques and survival metrics. Our cohort, drawn from a primary OSCC surgery population at our clinic, provided a rich dataset encompassing demographics, clinical parameters, and detailed surgical records. Two neck dissection techniques were analyzed: the Supraomohyoid Selective Neck Dissection (SND), which targets lymph nodes at Levels I–III, and Other Dissections (OD), which involve a more extensive extraction including Levels IV and V. Kaplan-Meier survival curves and Cox proportional hazards models assessed the influence of lymph node dissection on postoperative outcomes.Results: Findings indicated that each additional lymph node removed was associated with a 0.289-day increase in hospitalization (p = 0.002), yet no significant link was found between dissection techniques or total lymph node extraction count and survival metrics. Levels I to III emerged as critical areas with the highest likelihood of yielding tumor-positive lymph nodes, emphasizing the significance of these levels.Discussion: The study suggests that more extensive dissection does not necessarily confer survival benefits, highlighting the importance of strategic surgical focus and the potential for tailored interventions that prioritize disease-specific lymph node levels to optimize patient recovery and prognosis
Design and in vivo evaluation of an intraocular electrode for ciliary muscle biopotential measurement in a non-human primate model of human accommodation
No full textThe measurement of electrical potentials in the human body is becoming increasingly important in healthcare as a valuable diagnostic parameter. In ophthalmology, while these signals are primarily used to assess retinal function, other applications, such as recording accommodation-related biopotentials from the ciliary muscle, remain poorly understood. Here, we present the development and evaluation of a novel implantable ring electrode for recording biopotentials from the ciliary muscle. Inspired by capsular tension rings, the electrode was fabricated using laser cutting, wiring, and physical vapor deposition coating. The constant impedance and weight over a simulated aging period of 391 days, demonstrated the electrode’s stability. In vivo testing in non-human primates further validated the electrode’s surgical handling and long-term stability, with no delamination or tissue ingrowth after 100 days of implantation. Recorded biopotentials from the ciliary muscle (up to 700 µV) exceeded amplitudes reported in the literature. While the results are promising, further research is needed to investigate the signal quality and origin as well as the correlation between these signals and ciliary muscle activity. Ultimately, this electrode will be used in an implanted device to record ciliary muscle biopotentials to control an artificial lens designed to restore accommodation in individuals with presbyopia
Disparate mechanisms counteract extraneous CRISPR RNA production in type II-C CRISPR-Cas systems
No full textValve-sparing aortic root replacement: strategies to avoid residual aortic regurgitation
No full textObjectiveThe study objective was to identify quantitative criteria to avoid residual aortic valve regurgitation after valve-sparing aortic root replacement.MethodsBetween 2016 and 2023, 738 adult patients were recruited into the German Aortic Root Repair Registry. A total of 562 patients with datasets on aortic root measurements and tricuspid valve treated with reimplantation valve-sparing aortic root replacement were selected. End points were any grade of residual aortic valve regurgitation and postrepair coaptation height. Tested variables included procedural and anatomic characteristics, including length of cusp margins and geometric cusp heights.ResultsThe optimal classifier predicting freedom from residual aortic valve regurgitation was cusp coaptation height 8 to 9 mm or more (sensitivity = 0.7-0.8). Annular downsizing alone was not useful to predict residual aortic valve regurgitation (P = .472, 95% area CI, 0.414-0.54). Patients with a mean free margin length of at least 45 mm and a sum of free margin lengths of at least 125 mm were more likely to present coaptation heights of at least 10 mm (R2 0.038, P = .006).ConclusionsThe target coaptation height after valve-sparing aortic root replacement should exceed 8 to 9 mm. Chances of achieving it can be estimated on the basis of a measurement of cusp quantity. If in doubt when inspecting a valve, numerical criteria can help with surgical decision-making in favor of or against a valve-sparing approach