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In Georgia’s Lesser Caucasus, extremely species rich wooded grasslands are still used as pastures or meadows. These silvopastoral systems are one of the oldest land-use types in Europe, hosting both light-demanding and shade-tolerant species. However, in Europe silvopastoral systems have decreased over the past centuries. The aim of this study is to map, quantify, and classify the local land use and forest types in comparison to the potential natural vegetation to analyze and evaluate the high-mountain landscape pattern. Therefore, we mapped a 223 km2 study area and classified this mountainous terrain by topographical variables in a cluster analysis. Our results revealed a small-scale pattern of agriculture and forest in the study area, both strongly interlinked. The forest pattern strongly depends on altitude and aspect. The mentioned wooded grassland consists of forests with varying canopy covers connecting the settlement-near pastures and meadows in the montane belt with the natural open grassland in the alpine belts. The forest is in a near-natural condition compared with the potential natural vegetation. However, the quantifications revealed shrub encroachment indicating land-use abandonment. The compiled GIS-maps and the spatial classification of the landscape can be used to support sustainable management strategies in forestry and agriculture.

High mountain ecosystems, with strong topographic and climatic gradients, are fragile and particularly sensitive to changes in land use. The abandonment of historic cultural landscapes has often led to changes in the pattern of land cover and thus, to a shift in the functions of high mountain landscapes, like fresh water supply, productivity or erosion control. In order to understand the effects of land-use change on the land-cover pattern at the local and regional scale, we analyzed and classified the mountainous landscape structure in the Kazbegi region in Georgia, located in the Central Greater Caucasus. For 13 settlements, we determined the land cover as present in 1987 and 2015, and quantified the changes over time to detect land-cover development trends for each settlement. Using a cluster analysis, the study area was analyzed regarding to topography (altitude, aspect, slope) and distance to settlements at the regional scale to gain six groups with separating conditions. Furthermore, each settlement was classified according to topography and land-cover change to obtain site-specific, comparative development trends. Our results show that this Caucasian high-mountain landscape is characterized by open grassland (67%) used as pasture and hay meadow, and natural birch forests (7%) in patches in the upper half of the subalpine belt. Within the settlements but also in their surroundings, field vegetables are cultivated in home gardens (1%). Land-cover change during the observation period mainly affected the cultural grassland with hay meadow abandonment. Moreover, shrubbery and forest expanded considerably on abandoned pastures. We further detected a strong relationship to topography that considerably varied between settlements resulting in specific trends in land-use change. Hay-making and arable land cultivation are focused today on sun-exposed and gentle slopes near the settlements. Shrub encroachment and reforestations were localized on farther distances and mostly on north-exposed slopes. Besides providing basic information about the historic and current land-use and land-cover patterns, our results quantify the landscape change during almost 30 years. A spatio-temporal analysis revealed an understanding of how land-use decisions influence the landscape pattern. In the context of societal development, regional socioeconomic processes, like shifts in the agricultural structure and population outmigration, seem to be societal drivers of changes. Our findings reveal linkages and interrelationships between natural, human-induced environmental and socioeconomic processes within high-mountain socio-ecological systems. Moreover, we suggest that sustainable land-use strategies for spatial development on sub-regional level, especially in marginal high-mountain regions, should consider topography and its influence on land-use change.

Aims: The encroachment of tree and shrub species in high mountains is an increasing worldwide phenomenon, which is expected to dramatically alter high-mountain ecosystems and their functioning. Moreover it indicates in some cases a reforestation process, which will result in important ecological and social benefits, including carbon sequestration and protection against landslides. We therefore examined the spatial extent of forest growth and shrub encroachment mainly of birch (Betula litwinowii) in the sub-alpine belt of the Central Greater Caucasus between 1987 and 2010 and its relation to topographic site conditions. Location: Kazbegi district, Central Greater Caucasus, Georgia. Methods: We analysed 155 vegetation relevés sampled in 2009, 2011 and 2015, mainly derived from the Caucasus Vegetation Database, to obtain information about topographic site conditions and structure of B. litwinowii stands. B. litwinowii forest growth was assessed by digitizing the forest outlines from aerial and space-borne imagery (1987, 2005 and 2010). To identify areas of B. litwinowii encroachment as an indicator for different encroachment stages, we modelled the tree and shrub cover using the Random Forest algorithm. Results: We found four types of B. litwinowii stands, characterized by different tree and shrub coverage (initial Bromus variegatus–Betula litwinowii encroachment indicating the first stage of succession, Aconitum nasutum–Betula litwinowii forest, Rubus idaeus–Betula litwinowii forest and Rhododendron caucasicum–Betula litwinowii tree line scrubs). B. litwinowii forest increased 25% compared to 1987 mainly in an uphill direction. Furthermore the modelled tree and shrub cover (R2 = .69) could be related to the four vegetation types. Conclusions: Our results indicate a recent trend towards shrub encroachment and consequently reforestation in the Kazbegi region.

Systemic and localized ischemia and reperfusion injury remain clinically relevant issues after organ transplantation and contribute to organ dysfunctions, among which acute kidney injury is one of the most common. An in vitro test-circuit for normothermic perfusion of porcine kidneys after warm ischemia was used to investigate the antioxidant properties of vitamin C during reperfusion. Vitamin C is known to enhance microcirculation, reduce endothelial permeability, prevent apoptosis, and reduce inflammatory reactions. Based on current evidence about the pleiotropic effects of vitamin C, we hypothesize that the antioxidant properties of vitamin C might provide organ-protection and improve the kidney graft function in this model of ischemia and reperfusion. Methods: 10 porcine kidneys from 5 Landrace pigs were perfused in vitro for 6 h. For each experiment, both kidneys of one animal were perfused simultaneously with a 1:1 mixture of autologous blood and modified Ringer’s solution at 38 °C and 75 mmHg continuous perfusion pressure. One kidney was treated with a 500 mg bolus injection of vitamin C into the perfusate, followed by continuous infusion of 60 mg/h vitamin C. In the control test circuit, an equal volume of Ringer’s solution was administered as a placebo. Perfusate samples were withdrawn at distinct points in time during 6 h of perfusion for blood gas analyses as well as measurement of serum chemistry, oxidative stress and antioxidant capacity. Hemodynamic parameters and urine excretion were monitored continuously. Histological samples were analyzed to detect tubular- and glomerular-injury. Results: vitamin C administration to the perfusate significantly reduced oxidative stress (49.8 ± 16.2 vs. 118.6 ± 23.1 mV; p = 0.002) after 6 h perfusion, and increased the antioxidant capacity, leading to red blood cell protection and increased hemoglobin concentrations (5.1 ± 0.2 vs. 3.9 ± 0.6 g/dL; p = 0.02) in contrast to placebo treatment. Kidney function was not different between the groups (creatinine clearance vit C: 2.5 ± 2.1 vs. placebo: 0.5 ± 0.2 mL/min/100 g; p = 0.9). Hypernatremia (187.8 ± 4.7 vs. 176.4 ± 5.7 mmol/L; p = 0.03), and a lower, but not significant decreased fractional sodium excretion (7.9 ± 2 vs. 27.7 ± 15.3%; p = 0.2) were observed in the vitamin C group. Histological analysis did not show differences in tubular- and glomerular injury between the groups. Conclusion: Vitamin C treatment increased the antioxidant capacity of in vitro perfused kidney grafts, reduced oxidative stress, preserved red blood cells as oxygen carrier in the perfusate, but did not improve clinically relevant parameters like kidney function or attenuate kidney damage. Nevertheless, due to its antioxidative properties vitamin C might be a beneficial supplement to clinical kidney graft perfusion protocols.

Zygnematophyceae are the algal sisters of land plants. Here we sequenced four genomes of filamentous Zygnematophyceae, including chromosome-scale assemblies for three strains of Zygnema circumcarinatum . We inferred traits in the ancestor of Zygnematophyceae and land plants that might have ushered in the conquest of land by plants: expanded genes for signaling cascades, environmental response, and multicellular growth. Zygnematophyceae and land plants share all the major enzymes for cell wall synthesis and remodifications, and gene gains shaped this toolkit. Co-expression network analyses uncover gene cohorts that unite environmental signaling with multicellular developmental programs. Our data shed light on a molecular chassis that balances environmental response and growth modulation across more than 600 million years of streptophyte evolution. Genome assemblies of four filamentous Zygnematophyceae and co-expression network analyses shed light on the evolutionary roots of the mechanism for balancing environmental responses and multicellular growth.

We present the direct imaging discovery of a giant planet orbiting the young star AF Lep, a 1.2 \\(M_{\\odot}\\) member of the 24 \\(\\pm\\) 3 Myr \\(\\beta\\) Pic moving group. AF Lep was observed as part of our ongoing high-contrast imaging program targeting stars with astrometric accelerations between Hipparcos and Gaia that indicate the presence of substellar companions. Keck/NIRC2 observations in \\(L'\\) with the Vector Vortex Coronagraph reveal a point source, AF Lep b, at \\({\\approx}340\\) mas which exhibits orbital motion at the 6-\\(\\sigma\\) level over the course of 13 months. A joint orbit fit yields precise constraints on the planet's dynamical mass of 3.2\\(^{+0.7}_{-0.6}\\) \\(M_\\mathrm{Jup}\\), semi-major axis of \\(8.4^{+1.1}_{-1.3}\\) au, and eccentricity of \\(0.24^{+0.27}_{-0.15}\\). AF Lep hosts a debris disk located at \\(\\sim\\)50 au, but it is unlikely to be sculpted by AF Lep b, implying there may be additional planets in the system at wider separations. The stellar inclination (\\(i_* = 54^{+11}_{-9} {}^\\circ\\)) and orbital inclination (\\(i_o = 50^{+9}_{-12} {}^\\circ\\)) are in good agreement, which is consistent with the system having spin-orbit alignment. AF Lep b is the lowest-mass imaged planet with a dynamical mass measurement and highlights the promise of using astrometric accelerations as a tool to find and characterize long-period planets.

The filamentous and unicellular algae of the class Zygnematophyceae are the closest algal relatives of land plants. Inferring the properties of the last common ancestor shared by these algae and land plants allows us to identify decisive traits that enabled the conquest of land by plants. We sequenced four genomes of filamentous Zygnematophyceae (three strains of and one strain of ) and generated chromosome-scale assemblies for all strains of the emerging model system . Comparative genomic analyses reveal expanded genes for signaling cascades, environmental response, and intracellular trafficking that we associate with multicellularity. Gene family analyses suggest that Zygnematophyceae share all the major enzymes with land plants for cell wall polysaccharide synthesis, degradation, and modifications; most of the enzymes for cell wall innovations, especially for polysaccharide backbone synthesis, were gained more than 700 million years ago. In Zygnematophyceae, these enzyme families expanded, forming co-expressed modules. Transcriptomic profiling of over 19 growth conditions combined with co-expression network analyses uncover cohorts of genes that unite environmental signaling with multicellular developmental programs. Our data shed light on a molecular chassis that balances environmental response and growth modulation across more than 600 million years of streptophyte evolution.

With a dynamical mass of \\(3 \\, M_\\mathrm{Jup}\\), the recently discovered giant planet AF Lep b is the lowest-mass imaged planet with a direct mass measurement. Its youth and spectral type near the L/T transition make it a promising target to study the impact of clouds and atmospheric chemistry at low surface gravities. In this work, we present JWST/NIRCam imaging of AF Lep b. Across two epochs, we detect AF Lep b in F444W (\\(4.4 \\, \\mathrm{\\mu m}\\)) with S/N ratios of \\(9.6\\) and \\(8.7\\), respectively. At the planet's separation of \\(320 \\, \\mathrm{mas}\\) during the observations, the coronagraphic throughput is \\({\\approx}7\\%\\), demonstrating that NIRCam's excellent sensitivity persists down to small separations. The F444W photometry of AF Lep b affirms the presence of disequilibrium carbon chemistry and enhanced atmospheric metallicity. These observations also place deep limits on wider-separation planets in the system, ruling out \\(1.1 \\, M_\\mathrm{Jup}\\) planets beyond \\(15.6 \\, \\mathrm{au}\\) (\\(0.58\\) arcsec), \\(1.1 \\, M_\\mathrm{Sat}\\) planets beyond \\(27 \\, \\mathrm{au}\\) (\\(1\\) arcsec), and \\(2.8 \\, M_\\mathrm{Nep}\\) planets beyond \\(67 \\, \\mathrm{au}\\) (\\(2.5\\) arcsec). We also present new Keck/NIRC2 \\(L'\\) imaging of AF Lep b; combining this with the two epochs of F444W photometry and previous Keck \\(L'\\) photometry provides limits on the long-term \\(3{-}5 \\, \\mathrm{\\mu m}\\) variability of AF Lep b on months-to-years timescales. AF Lep b is the closest-separation planet imaged with JWST to date, demonstrating that planets can be recovered well inside the nominal (50\\% throughput) NIRCam coronagraph inner working angle.