Forest responses to simulated elevated CO2 under alternate hypotheses of size‐ and age‐dependent mortality

Elevated atmospheric carbon dioxide (eCO₂) is predicted to increase growth rates of forest trees. The extent to which increased growth translates to changes in biomass is dependent on the turnover time of the carbon, and thus tree mortality rates. Size‐ or age‐dependent mortality combined with increased growth rates could result in either decreased carbon turnover from a speeding up of tree life cycles, or increased biomass from trees reaching larger sizes, respectively. However, most vegetation models currently lack any representation of size‐ or age‐dependent mortality and the effect of eCO₂ on changes in biomass and carbon turnover times is thus a major source of uncertainty in predictions of future vegetation dynamics. Using a reduced‐complexity form of the vegetation demographic model the Functionally Assembled Terrestrial Ecosystem Simulator to simulate an idealised tropical forest, we find increases in biomass despite reductions in carbon turnover time in both size‐ and age‐dependent mortality scenarios in response to a hypothetical eCO₂‐driven 25% increase in woody net primary productivity (wNPP). Carbon turnover times decreased by 9.6% in size‐dependent mortality scenarios due to a speeding up of tree life cycles, but also by 2.0% when mortality was age‐dependent, as larger crowns led to increased light competition. Increases in aboveground biomass (AGB) were much larger when mortality was age‐dependent (24.3%) compared with size‐dependent (13.4%) as trees reached larger sizes before death. In simulations with a constant background mortality rate, carbon turnover time decreased by 2.1% and AGB increased by 24.0%, however, absolute values of AGB and carbon turnover were higher than in either size‐ or age‐dependent mortality scenario. The extent to which AGB increases and carbon turnover decreases will thus depend on the mechanisms of large tree mortality: if increased size itself results in elevated mortality rates, then this could reduce by about half the increase in AGB relative to the increase in wNPP.     

Quantitative evaluation of intraspecific genetic diversity in a natural fish population using environmental DNA analysis

Recent advances in environmental DNA (eDNA) analysis using high‐throughput sequencing (HTS) enable evaluation of intraspecific genetic diversity in a population. As the intraspecific genetic diversity provides invaluable information for wildlife conservation and management, there is an increasing demand to apply eDNA analysis to population genetics and the phylogeography by quantitative evaluation of intraspecific diversity. However, quantitative evaluations of intraspecific genetic diversity using eDNA is not straightforward because the number of eDNA sequence reads obtained by HTS may not be an index of the quantity of eDNA. In this study, to quantitatively evaluate genetic diversity using eDNA analysis, we applied a quantitative eDNA metabarcoding method using the internal standard DNAs. We targeted Ayu (Plecoglossus altivelis altivelis) and added internal standard DNAs with known copy numbers to each eDNA sample obtained from three rivers during the library preparation process. The sequence reads of each Ayu haplotype were successfully converted to DNA copy numbers based on the relationship between the copy numbers and sequence reads of the internal standard DNAs. In all rivers, the calculated copy number of each haplotype showed a significant positive correlation with the haplotype frequency estimated by a capture‐based survey. Furthermore, estimates of genetic indicators such as nucleotide diversity based on the eDNA copy numbers were comparable with those estimated based on a capture‐based study. Our results demonstrate that eDNA analysis with internal standard DNAs enables reasonable quantification of intraspecific genetic diversity, and this method could thus be a promising tool in the field of population genetics and phylogeography.     

不同经皮克氏针内固定术治疗儿童GartlandⅡ、Ⅲ型肱骨髁上骨折疗效对比的回顾性分析

摘要 目的：对比不同经皮克氏针内固定术治疗GartlandⅡ、Ⅲ型肱骨髁上骨折患儿的治疗效果。方法：回顾性分析2017年3月~2020年3月期间我院收治的90例GartlandⅡ、Ⅲ型肱骨髁上骨折患儿的临床资料,根据治疗方式的不同,将患儿分为A组47例（采用切开复位经皮克氏针内固定术治疗）和B组43例（采用闭合复位经皮克氏针内固定术治疗）。观察两组疗效情况、围术期指标情况及并发症发生率。结果：A组、B组的优良率组间对比无统计学差异（P>0.05）。B组的手术时间、骨折愈合时间、住院时间均短于A组,术中失血量少于A组,组间对比差异有统计学意义（P<0.05）。两组术后并发症发生率比较差异无统计学意义（P>0.05）。结论：GartlandⅡ、Ⅲ型肱骨髁上骨折患儿采用闭合复位或切开复位经皮克氏针内固定术均可获得良好的手术效果,其中闭合复位在缩短手术时间、骨折愈合时间、住院时间和减少术中失血量方面更具备优势。     

Three-dimensional design optimisation of patient-specific femoral plates as a means of bone remodelling reduction

Previous investigations into the optimisation of internal plates have mostly focused on the material properties of the implant. In this work, we optimise the shape, size and placement of the plate for successfully minimising bone remodelling around the implant. A design optimisation algorithm based on strain energy density criterion, combined with the finite element analysis, has been used in this study. The main optimisation goal was to reduce this change and keep it close to the conditions of an intact femur. The results suggest that the anterolateral side of the bone would be the optimum location for the plate, as for the geometry, the optimum moves towards having a thick, wide and short plate. These important results could be directly applicable to orthopaedic surgeons treating a femur fracture with internal plates. Since the optimisation algorithm remains the same for any patient, this advancement provides the surgeon with a tool to minimise the post surgery remodelling by trying to maintain the natural structure of the bone.     

Prediction of shape and internal structure of the proximal femur using a modified level set method for structural topology optimisation

A computational framework was developed to simulate the bone remodelling process as a structural topology optimisation problem. The mathematical formulation of the Level Set technique was extended and then implemented into a coronal plane model of the proximal femur to simulate the remodelling of internal structure and external geometry of bone into the optimal state. Results indicated that the proposed approach could reasonably mimic the major geometrical and material features of the natural bone. Simulation of the internal bone remodelling on the typical gross shape of the proximal femur, resulted in a density distribution pattern with good consistency with that of the natural bone. When both external and internal bone remodelling were simulated simultaneously, the initial rectangular design domain with a regularly distributed mass reduced gradually to an optimal state with external shape and internal structure similar to those of the natural proximal femur.     

Phylogenetic relationships of Italian Bellevalia species (Asparagaceae), inferred from morphology,karyology and molecular systematics

The seven Bellevalia species and subspecies known from Italy, representing about 10% of the genus and three out of six sections, were studied. An integrated morphological, karyological and molecular approach was used to infer phylogenetic and systematic relationships among them. B. romana (the generitype) is the most distinctive species on karyotype asymmetry grounds. B. boissieri and B.dubia, usually considered as subspecies of one species (the latter endemic to Sicily), deserve specific status based on biparental nrDNA markers (internal transcribed spacer, ITS), since they do not form a single clade. The allotetraploid endemic B. pelagica, morphologically similar to B. romana, is sister to the latter under parsimony, both in morphological and ITS trees; it is also related with B. dubia, based on karyotype asymmetry and a uniparental cpDNA marker (trnL^(UAA)–trnF^(GAA) IGS (intergenic spacer)). A second allotetraploid endemic, B. webbiana, is closely related, on morphological, karyological and molecular grounds, with B. boissieri and B. ciliata, and also with B. trifoliata, three species that might all involved in its origin. B. sect. Conicae Feinbr. and sect. Nutantes Feinbr. are here typified, the former (type: B. ciliata) is most likely a synonym of the latter (type: B. trifoliata).     

Trafficking Highways to the Intercalated Disc: New Insights Unlocking the Specificity of Connexin 43 Localization

Abstract

With each heartbeat, billions of cardiomyocytes work in concert to propagate the electrical excitation needed to effectively circulate blood. Regulated expression and timely delivery of connexin proteins to form gap junctions at the specialized cell–cell contact region, known as the intercalated disc, is essential to ventricular cardiomyocyte coupling. We focus this review on several regulatory mechanisms that have been recently found to govern the lifecycle of connexin 43 (Cx43), the short-lived and most abundantly expressed connexin in cardiac ventricular muscle. The Cx43 lifecycle begins with gene expression, followed by oligomerization into hexameric channels, and then cytoskeletal-based transport toward the disc region. Once delivered, hemichannels interact with resident disc proteins and are organized to effect intercellular coupling. We highlight recent studies exploring regulation of Cx43 localization to the intercalated disc, with emphasis on alternatively translated Cx43 isoforms and cytoskeletal transport machinery that together regulate Cx43 gap junction coupling between cardiomyocytes.     

3D Coupling of Fibronectin Fibril Arrangement with Topology of Ventral Plasma Membrane

Abstract

Interaction of integrins with extracellular matrices is essential for cell adhesion to substrata. Ventral surfaces of fibroblasts adhering to flat substrata are not flat but have uneven 3D topology. However, spatial relationship between the topology of the ventral cell surface and arrangement of extracellular matrix fibrils remains unclear. Here, we report a novel and simple method based on total internal reflection fluorescence microscopy to quantify the distance between the ventral plasma membrane and the glass substratum. We observe that the distance varies from <?25 nm at focal adhesions to 40–50 nm at close contacts and >?80 nm in other regions. Furthermore, by applying this novel method, we show that fibronectin fibrils are also separated from the substratum in regions where the ventral cell surface-substratum distance is >?80 nm. Our results reveal that fibronectin fibrils are not simply adsorbed to the glass substratum but follow the ventral cell surface topology.     

应用坚固内固定技术治疗颌骨骨折的效果分析

目的：探究坚固内固定技术对颌骨骨折的治疗运用,为颌骨骨折的治疗方法选择提供理论指导。方法：选取我科自2009年4月-2012年7月收治的80例下颌骨骨折患者行手术切开复位、小型和微型钛板坚固内固定术治疗,纳入内固定组,并选取同期80例行颌间固定的颌骨骨折患者,纳入颌间固定组,对比两组患者治疗效果。结果：两组患者术后3个月张口度及张口型均得到明显改善,内固定组改善程度较颌间固定组更为显著（P〈0．05）;内固定组治疗周数、口臭及咬合错乱发生率均低于颌间固定组（P〈0．05）;内固定组疗效评价优43例,良26例,有效率86．3％,颌间固定组分别为31例和17例,有效率60．0％,内固定组治疗效果显著优于颌间固定组（P〈0．05）。结论：坚固内固定技术具有组织相容性高、口功能恢复快、不良反应发生率低等优势,是治疗颌骨骨折的安全、可靠、简便的治疗方案,能够有效保证患者的预后和生活质量,值得临床普遍应用。