Effects of urbanization and accessibility to sanitation services on water quality in urban streams in Uruguay.

The world's urban population is growing rapidly, and threatening natural ecosystems, especially streams. Urbanization leads to stream alterations, increased peak flow frequencies, and reduced water quality due to pollutants, morphological changes, and biodiversity loss, known as the urban stream syndrome. However, a shift towards recognizing urban streams as valuable natural systems is occurring, emphasizing green infrastructure and nature-based solutions. This study in Uruguay examined water quality in various watersheds with different urbanization levels and socio-environmental characteristics along a precipitation gradient. Using Geographic Information Systems (GIS) and in situ data, we assessed physicochemical parameters, generated territorial variables, and identified key predictors of water quality. We found that urbanization, particularly urban areas, paved areas, and populations without sanitation, significantly influenced water quality parameters. These factors explained over 50% of the variation in water quality indicators. However, the relationship between urbanization and water quality was non-linear, with abrupt declines after specific urban intensity thresholds. Our results illustrate that ensuring sanitation networks and managing green areas effectively are essential for preserving urban stream water quality. This research underscores the importance of interdisciplinary teams and localized data for informed freshwater resource management.

Baseline assessment of the hydrological network and land use in riparian buffers of Pampean streams of Uruguay.

The integrated assessment of stream networks and terrestrial land use contributes a critical foundation for understanding and mitigating potential impacts on stream ecology. Riparian zone delineation and management is a key component for regulating water quality, particularly in agricultural watersheds. We present a national assessment of riparian zone land uses according to stream order for the entire hydrological network in the Uruguayan landscape in Southeastern South America. We classified over 82,500 km of streams and rivers in Uruguay into seven Strahler order classes and delineated riparian buffers of 100 and 500 m, depending on stream order, covering a total of 13% of the terrestrial land area in Uruguay. Natural vegetation cover in riparian zones averaged 77% among basins, whereby natural grassland dominated first and second order stream buffers at 58% and 49%, respectively. This highlighted the importance of grasslands in headwater regions of the country. Riparian forests formed corridors along larger streams, representing a mere 9% of buffers in first order streams but reaching 46% of buffers of 6th order streams. Among the six major basins of Uruguay, we found differences in the relative importance of riparian forests and crop cover in headwater stream riparian zones, as well as differences in relative crop cover within riparian zones. Results show that streams in subtropical grassland landscapes originate in open grassland environments, which has major implications for thermal regimes, carbon inputs, and stream biodiversity. Riparian buffer management should consider geographic differences among different basins and ecoregions within Uruguay.

Machine Learning for Medical Coding in Healthcare Surveys.

Objectives Medical coding, or the translation of healthcare information into numeric codes, is expensive and time intensive. This exploratory study evaluates the use of machine learning classifiers to perform automated medical coding for large statistical healthcare surveys.

Induction of muscle-regenerative multipotent stem cells from human adipocytes by PDGF-AB and 5-azacytidine.

Terminally differentiated murine osteocytes and adipocytes can be reprogrammed using platelet-derived growth factor-AB and 5-azacytidine into multipotent stem cells with stromal cell characteristics. We have now optimized culture conditions to reprogram human adipocytes into induced multipotent stem (iMS) cells and characterized their molecular and functional properties. Although the basal transcriptomes of adipocyte-derived iMS cells and adipose tissue-derived mesenchymal stem cells were similar, there were changes in histone modifications and CpG methylation at cis-regulatory regions consistent with an epigenetic landscape that was primed for tissue development and differentiation. In a non-specific tissue injury xenograft model, iMS cells contributed directly to muscle, bone, cartilage, and blood vessels, with no evidence of teratogenic potential. In a cardiotoxin muscle injury model, iMS cells contributed specifically to satellite cells and myofibers without ectopic tissue formation. Together, human adipocyte-derived iMS cells regenerate tissues in a context-dependent manner without ectopic or neoplastic growth.

Correction to: Water quality evaluation of two urban streams in Northwest Uruguay: are national regulations for urban stream quality sufficient?

The original version of this article unfortunately contained an error in the published paper.

Water quality evaluation of two urban streams in Northwest Uruguay: are national regulations for urban stream quality sufficient?

Poor water quality in urban streams places at risk the health of urban residents and the integrity of urban environments, ultimately leading to the "urban stream syndrome." In response to growing concerns regarding urban streams in Uruguay, we evaluated the spatiotemporal variation in water quality parameters in two urban streams, the Ceibal and La Curtiembre streams, over 12-18 months. A proposal for an Urban Water Quality Index (UWQI) was developed based on national water quality standards for two stream classes to assess variability in overall stream condition over time. Both streams displayed extremely high levels of fecal coliform concentrations in mid-downstream sites and relatively high levels of total dissolved phosphorus and ammonia well above the national standards of 0.025 mg/L and 0.02 mg/L, respectively. Nitrate was consistently below the national maximum of 44.3 mg/L, calling to question the adequacy of this standard for designated uses. Over 40% of samples had oxygen levels below the national standard of 5 mg/L, and a dead zone (average 1.5 mg/L) was detected in the downstream reach of the La Curtiembre stream. Despite differences in land use and urban context, monthly observations of nutrients and coliforms indicated high levels of contamination in mid-downstream reaches, which could present a health risk for the populations in Paysandú and Salto. This study highlights the degradation of urban streams in two major cities in Uruguay and the need for a comparative diagnosis of stream condition as a basis for decision-making regarding urban development and water resources.

Irradiation impairs mitochondrial function and skeletal muscle oxidative capacity: significance for metabolic complications in cancer survivors.

BACKGROUND: Metabolic complications are highly prevalent in cancer survivors treated with irradiation but the underlying mechanisms remain unknown. METHODS: Chow or high fat-fed C57Bl/6J mice were irradiated (6Gy) before investigating the impact on whole-body or skeletal muscle metabolism and profiling their lipidomic signature. Using a transgenic mouse model (Tg:Pax7-nGFP), we isolated muscle progenitor cells (satellite cells) and characterised their metabolic functions. We recruited childhood cancer survivors, grouped them based on the use of total body irradiation during their treatment and established their lipidomic profile. RESULTS: In mice, irradiation delayed body weight gain and impaired fat pads and muscle weights. These changes were associated with impaired whole-body fat oxidation in chow-fed mice and altered ex vivo skeletal muscle fatty acid oxidation, potentially due to a reduction in oxidative fibres and reduced mitochondrial enzyme activity. Irradiation led to fasting hyperglycaemia and impaired glucose uptake in isolated skeletal muscles. Cultured satellite cells from irradiated mice showed decreased fatty acid oxidation and reduced glucose uptake, recapitulating the host metabolic phenotype. Irradiation resulted in a remodelling of lipid species in skeletal muscles, with the extensor digitorum longus muscle being particularly affected. A large number of lipid species were reduced, with several of these species showing a positive correlation with mitochondrial enzymes activity. In cancer survivors exposed to irradiation, we found a similar decrease in systemic levels of most lipid species, and lipid species that increased were positively correlated with insulin resistance (HOMA-IR). CONCLUSION: Irradiation leads to long-term alterations in body composition, and lipid and carbohydrate metabolism in skeletal muscle, and affects muscle progenitor cells. Such changes result in persistent impairment of metabolic functions, providing a new mechanism for the increased prevalence of metabolic diseases reported in irradiated individuals. In this context, changes in the lipidomic signature in response to irradiation could be of diagnostic value.

Changes in Myosin Heavy Chain Isoforms Along the Length of Orbital Fibers in Rabbit Extraocular Muscle.

Purpose: Extraocular muscles express 10 myosin heavy chain (MyHC) isoforms that cater for a wide range of contractile speeds. We aim to characterize the variations in MyHC expression along the length of singly (SIFs) and multiply innervated fibers (MIFs) in the orbital layer of rabbit superior rectus muscle. Methods: Monospecific antibodies to nine MyHCs, including an anti-slow-tonic antibody characterized here were used to immunohistochemically map variations in MyHC distribution in serial sections along the muscle's full length. Results: The fastest MyHC, EO, is expressed at the endplate zone (EPZ) of SIFs, flanked proximally and distally by segments expressing the slower 2A, with or without embryonic MyHC. MIFs with constant diameter express α-cardiac MyHC at the EPZ, flanked by segments co-expressing α-cardiac/embryonic and possibly slow-tonic MyHCs. MIFs with varying diameter also express α-cardiac MyHC at the EPZ in their thin, central region, flanked by thin segments co-expressing α-cardiac/embryonic MyHCs, with long proximal and distal extensions of larger diameter that co-express embryonic/slow-tonic and α-cardiac or ß/slow MyHCs. Conclusions: Orbital fiber types express multiple MyHCs, with faster ones in SIFs, slower ones in MIFs, but all have fast EPZs and slower end segments. We hypothesize that these unique MyHC distributions enable these fibers to relax in two kinetically distinct phases while acting in an antagonistic manner during a saccade: the fast phases facilitate acceleration of eyeball rotation during agonist contraction, while the slow phases help its deceleration toward the visual target, thereby linearizing the saccade. These properties also facilitate pulley movements to implement Listing's law.

Parallel assembly of actin and tropomyosin, but not myosin II, during de novo actin filament formation in live mice.

Many actin filaments in animal cells are co-polymers of actin and tropomyosin. In many cases, non-muscle myosin II associates with these co-polymers to establish a contractile network. However, the temporal relationship of these three proteins in the de novo assembly of actin filaments is not known. Intravital subcellular microscopy of secretory granule exocytosis allows the visualisation and quantification of the formation of an actin scaffold in real time, with the added advantage that it occurs in a living mammal under physiological conditions. We used this model system to investigate the de novo assembly of actin, tropomyosin Tpm3.1 (a short isoform of TPM3) and myosin IIA (the form of non-muscle myosin II with its heavy chain encoded by Myh9) on secretory granules in mouse salivary glands. Blocking actin polymerization with cytochalasin D revealed that Tpm3.1 assembly is dependent on actin assembly. We used time-lapse imaging to determine the timing of the appearance of the actin filament reporter LifeAct-RFP and of Tpm3.1-mNeonGreen on secretory granules in LifeAct-RFP transgenic, Tpm3.1-mNeonGreen and myosin IIA-GFP (GFP-tagged MYH9) knock-in mice. Our findings are consistent with the addition of tropomyosin to actin filaments shortly after the initiation of actin filament nucleation, followed by myosin IIA recruitment.

On-target action of anti-tropomyosin drugs regulates glucose metabolism.

The development of novel small molecule inhibitors of the cancer-associated tropomyosin 3.1 (Tpm3.1) provides the ability to examine the metabolic function of specific actin filament populations. We have determined the ability of these anti-Tpm (ATM) compounds to regulate glucose metabolism in mice. Acute treatment (1 h) of wild-type (WT) mice with the compounds (TR100 and ATM1001) led to a decrease in glucose clearance due mainly to suppression of glucose-stimulated insulin secretion (GSIS) from the pancreatic islets. The impact of the drugs on GSIS was significantly less in Tpm3.1 knock out (KO) mice indicating that the drug action is on-target. Experiments in MIN6 ß-cells indicated that the inhibition of GSIS by the drugs was due to disruption to the cortical actin cytoskeleton. The impact of the drugs on insulin-stimulated glucose uptake (ISGU) was also examined in skeletal muscle ex vivo. In the absence of drug, ISGU was decreased in KO compared to WT muscle, confirming a role of Tpm3.1 in glucose uptake. Both compounds suppressed ISGU in WT muscle, but in the KO muscle there was little impact of the drugs. Collectively, this data indicates that the ATM drugs affect glucose metabolism in vivo by inhibiting Tpm3.1's function with few off-target effects.

Mutations in tropomyosin 4 underlie a rare form of human macrothrombocytopenia.

Platelets are anuclear cells that are essential for blood clotting. They are produced by large polyploid precursor cells called megakaryocytes. Previous genome-wide association studies in nearly 70,000 individuals indicated that single nucleotide variants (SNVs) in the gene encoding the actin cytoskeletal regulator tropomyosin 4 (TPM4) exert an effect on the count and volume of platelets. Platelet number and volume are independent risk factors for heart attack and stroke. Here, we have identified 2 unrelated families in the BRIDGE Bleeding and Platelet Disorders (BPD) collection who carry a TPM4 variant that causes truncation of the TPM4 protein and segregates with macrothrombocytopenia, a disorder characterized by low platelet count. N-Ethyl-N-nitrosourea-induced (ENU-induced) missense mutations in Tpm4 or targeted inactivation of the Tpm4 locus led to gene dosage-dependent macrothrombocytopenia in mice. All other blood cell counts in Tpm4-deficient mice were normal. Insufficient TPM4 expression in human and mouse megakaryocytes resulted in a defect in the terminal stages of platelet production and had a mild effect on platelet function. Together, our findings demonstrate a nonredundant role for TPM4 in platelet biogenesis in humans and mice and reveal that truncating variants in TPM4 cause a previously undescribed dominant Mendelian platelet disorder.

Recruitment Kinetics of Tropomyosin Tpm3.1 to Actin Filament Bundles in the Cytoskeleton Is Independent of Actin Filament Kinetics.

The actin cytoskeleton is a dynamic network of filaments that is involved in virtually every cellular process. Most actin filaments in metazoa exist as a co-polymer of actin and tropomyosin (Tpm) and the function of an actin filament is primarily defined by the specific Tpm isoform associated with it. However, there is little information on the interdependence of these co-polymers during filament assembly and disassembly. We addressed this by investigating the recovery kinetics of fluorescently tagged isoform Tpm3.1 into actin filament bundles using FRAP analysis in cell culture and in vivo in rats using intracellular intravital microscopy, in the presence or absence of the actin-targeting drug jasplakinolide. The mobile fraction of Tpm3.1 is between 50% and 70% depending on whether the tag is at the C- or N-terminus and whether the analysis is in vivo or in cultured cells. We find that the continuous dynamic exchange of Tpm3.1 is not significantly impacted by jasplakinolide, unlike tagged actin. We conclude that tagged Tpm3.1 may be able to undergo exchange in actin filament bundles largely independent of the assembly and turnover of actin.

How livestock and flooding mediate the ecological integrity of working forests in Amazon River floodplains.

The contribution of working forests to tropical conservation and development depends upon the maintenance of ecological integrity under ongoing land use. Assessment of ecological integrity requires an understanding of the structure, composition, and function and major drivers that govern their variability. Working forests in tropical river floodplains provide many goods and services, yet the data on the ecological processes that sustain these services is scant. In flooded forests of riverside Amazonian communities, we established 46 0.1-ha plots varying in flood duration, use by cattle and water buffalo, and time since agricultural abandonment (30-90 yr). We monitored three aspects of ecological integrity (stand structure, species composition, and dynamics of trees and seedlings) to evaluate the impacts of different trajectories of livestock activity (alleviation, stasis, and intensification) over nine years. Negative effects of livestock intensification were solely evident in the forest understory, and plots alleviated from past heavy disturbance increased in seedling density but had higher abundance of thorny species than plots maintaining low activity. Stand structure, dynamics, and tree species composition were strongly influenced by the natural pulse of seasonal floods, such that the defining characteristics of integrity were dependent upon flood duration (3-200 d). Forests with prolonged floods ≥ 140 d had not only lower species richness but also lower rates of recruitment and species turnover relative to forests with short floods <70 d. Overall, the combined effects of livestock intensification and prolonged flooding hindered forest regeneration, but overall forest integrity was largely related to the hydrological regime and age. Given this disjunction between factors mediating canopy and understory integrity, we present a subset of metrics for regeneration and recruitment to distinguish forest condition by livestock trajectory. Although our study design includes confounded factors that preclude a definitive assessment of the major drivers of ecological change, we provide much-needed data on the regrowth of a critical but poorly studied ecosystem. In addition to its emphasis on the dynamics of tropical wetland forests undergoing anthropogenic and environmental change, our case study is an important example for how to assess of ecological integrity in working forests of tropical ecosystems.

Iridium(I)/N-Heterocyclic Carbene Hybrid Materials: Surface Stabilization of Low-Valent Iridium Species for High Catalytic Hydrogenation Performance.

An Ir(I) (NHC)-based hybrid material was prepared using a methodology which allowed the precise positioning and isolation of the Ir centers along the pore channels of a silica framework. The full characterization of the material by solid-state NMR spectroscopy showed that the supported Ir sites were stabilized by the silica surface, as low-coordinated single-site complexes. The material is extremely efficient for the hydrogenation of functional alkenes. The catalytic performance (TOF and TON) is one to two orders of magnitude higher than those of their molecular Ir analogues, and could be related to the prevention of the bimolecular deactivation of Ir complexes observed under homogeneous conditions.

Regulation of cell proliferation by ERK and signal-dependent nuclear translocation of ERK is dependent on Tm5NM1-containing actin filaments.

ERK-regulated cell proliferation requires multiple phosphorylation events catalyzed first by MEK and then by casein kinase 2 (CK2), followed by interaction with importin7 and subsequent nuclear translocation of pERK. We report that genetic manipulation of a core component of the actin filaments of cancer cells, the tropomyosin Tm5NM1, regulates the proliferation of normal cells both in vitro and in vivo. Mouse embryo fibroblasts (MEFs) lacking Tm5NM1, which have reduced proliferative capacity, are insensitive to inhibition of ERK by peptide and small-molecule inhibitors, indicating that ERK is unable to regulate proliferation of these knockout (KO) cells. Treatment of wild-type MEFs with a CK2 inhibitor to block phosphorylation of the nuclear translocation signal in pERK resulted in greatly decreased cell proliferation and a significant reduction in the nuclear translocation of pERK. In contrast, Tm5NM1 KO MEFs, which show reduced nuclear translocation of pERK, were unaffected by inhibition of CK2. This suggested that it is nuclear translocation of CK2-phosphorylated pERK that regulates cell proliferation and this capacity is absent in Tm5NM1 KO cells. Proximity ligation assays confirmed a growth factor-stimulated interaction of pERK with Tm5NM1 and that the interaction of pERK with importin7 is greatly reduced in the Tm5NM1 KO cells.

An actin filament population defined by the tropomyosin Tpm3.1 regulates glucose uptake.

Actin has an ill-defined role in the trafficking of GLUT4 glucose transporter vesicles to the plasma membrane (PM). We have identified novel actin filaments defined by the tropomyosin Tpm3.1 at glucose uptake sites in white adipose tissue (WAT) and skeletal muscle. In Tpm 3.1-overexpressing mice, insulin-stimulated glucose uptake was increased; while Tpm3.1-null mice they were more sensitive to the impact of high-fat diet on glucose uptake. Inhibition of Tpm3.1 function in 3T3-L1 adipocytes abrogates insulin-stimulated GLUT4 translocation and glucose uptake. In WAT, the amount of filamentous actin is determined by Tpm3.1 levels and is paralleled by changes in exocyst component (sec8) and Myo1c levels. In adipocytes, Tpm3.1 localizes with MyoIIA, but not Myo1c, and it inhibits Myo1c binding to actin. We propose that Tpm3.1 determines the amount of cortical actin that can engage MyoIIA and generate contractile force, and in parallel limits the interaction of Myo1c with actin filaments. The balance between these actin filament populations may determine the efficiency of movement and/or fusion of GLUT4 vesicles with the PM.

Tropomyosin isoforms support actomyosin biogenesis to generate contractile tension at the epithelial zonula adherens.

Epithelial cells generate contractile forces at their cell-cell contacts. These are concentrated at the specialized apical junction of the zonula adherens (ZA), where a ring of stabilized E-cadherin lies adjacent to prominent actomyosin bundles. Coupling of adhesion and actomyosin contractility yields tension in the junction. The biogenesis of junctional contractility requires actin assembly at the ZA as well as the recruitment of nonmuscle myosin II, but the molecular regulators of these processes are not yet fully understood. We now report a role for tropomyosins 5NM1 (Tm5NM1) and 5NM2 (Tm5NM2) in their generation. Both these tropomyosin isoforms were found at the ZA and their depletion by RNAi or pharmacological inhibition reduced both F-actin and myosin II content at the junction. Photoactivation analysis revealed that the loss of F-actin was attributable to a decrease in filament stability. These changes were accompanied by a decrease in E-cadherin content at junctions. Ultimately, both long-term depletion of Tm5NM1/2 and acute inhibition with drugs caused junctional tension to be reduced. Thus these tropomyosin isoforms are novel contributors to junctional contractility and integrity.