Protein kinase C contributes to desensitization of ANG II signaling in adult rat cardiac fibroblasts

We have studiedG_q-linked ANG II signaling [inositol phosphate (IP)accumulation, Ca²⁺ mobilization] in primary cultures ofrat cardiac fibroblasts (CFs) and have found that ANG II initiates aprotein kinase C (PKC)-mediated negative feedback loop that rapidlyterminates the ANG II response. Pharmacological inhibition of PKC bystaurosporine and GF-109203X doubled IP production over that achievedin response to ANG II alone. Inhibition of PKC also led to largerCa²⁺ transients in response to ANG II, suggesting thatCa²⁺ mobilization was proportional toG_q-phospholipase C-IP₃ activity underthe conditions studied. Depletion of cellular PKC by overnight treatment with phorbol 12-myristate 13-acetate (PMA) similarly augmented ANG II-induced IP production. Acute activation of PKC by PMAhalved IP formation, with an EC₅₀1 nM; 4-PMA wasinactive. Time course data demonstrated that ANG II-mediated IPproduction fully desensitized within 30 s; PKC inhibition reducedthe rate and extent of this desensitization. In cells desensitized toANG II, a purinergic agonist still mobilized intracellularCa²⁺, indicating that desensitization was homologous. TheANG II-induced Ca²⁺ signal was fully resensitized within 30 min. The data demonstrate that a large portion of theIP-Ca²⁺ responses of rat CFs to ANG II are short-livedbecause of rapid, PKC-mediated desensitization.

     

Bacterial Cellulose-Binding Domain Modulates in Vitro Elongation of Different Plant Cells

Recombinant cellulose-binding domain (CBD) derived from the cellulolytic bacterium Clostridium cellulovorans was found to modulate the elongation of different plant cells in vitro. In peach (Prunus persica L.) pollen tubes, maximum elongation was observed at 50 μg mL⁻¹ CBD. Pollen tube staining with calcofluor showed a loss of crystallinity in the tip zone of CBD-treated pollen tubes. At low concentrations CBD enhanced elongation of Arabidopsis roots. At high concentrations CBD dramatically inhibited root elongation in a dose-responsive manner. Maximum effect on root hair elongation was at 100 μg mL⁻¹, whereas root elongation was inhibited at that concentration. CBD was found to compete with xyloglucan for binding to cellulose when CBD was added first to the cellulose, before the addition of xyloglucan. When Acetobacter xylinum L. was used as a model system, CBD was found to increase the rate of cellulose synthase in a dose-responsive manner, up to 5-fold compared with the control. Electron microscopy examination of the cellulose ribbons produced by A. xylinum showed that CBD treatment resulted in a splayed ribbon composed of separate fibrillar subunits, compared with a thin, uniform ribbon in the control.     

Changes in structure of savanna woodlands in northern Botswana following the impacts of elephants and fire

Fluctuations in densities of woody plant species were monitored in plots within three northern Botswana woodland types subjected to elephant damage and burning. Woodlands dominated by Baikiaea plurijuga and Colophospermum mopane sustained significant changes occurring on an annual basis, whereas Acacia erioloba plots maintained a typical structure. The structure of A. erioloba woodlands appeared to be influenced by factors other than elephants and the occurrence of fire. Woodlands dominated by C. mopane plants were subjected to obtrusive elephant damage, although the densities of tall trees remained largely unchanged. The effects of fire were most prominent in B. plurijuga woodlands. Tree densities declined consistently and plants of lower height classes, such as shrubs and seedlings increased in densities in areas subjected to a high occurrence of fire.     

Long-Term Weight Change: Association with Impaired Glucose Metabolism in Young Austrian Adults

Little is known about the associations between long-term weight change and the natural history of impaired fasting glucose (IFG) in young adults. We investigated the association between long-term body mass index (BMI) change and the risk of IFG using data of 24,930 20- to 40-year-old participants from the Vorarlberg Health Monitoring and Promotion Program (VHM&PP) cohort. Poisson models were applied to estimate the 10-year risk for new development of IFG (≥5.6 mmol/L), and persistence of IFG. Over 10 years, most men (68.2%) and women (70.0%) stayed within their initial BMI category. The risk for incident IFG was highest for men and women with persisting obesity (37.4% and 24.1%) and lowest with persisting normal weight (15.7% and 9.3%). Men transitioning from normal to overweight increased their risk of incident IFG by factor 1.45 (95%-CI: 1.31, 1.62), women by 1.70 (95%-CI: 1.50, 1.93), whereas transitioning from overweight to normal weight decreased the risk in men by 0.69 (95%-CI: 0.53, 0.90) and 0.94 (95%-CI: 0.66, 1.33) in women. Relative risks for men and women transitioning from obesity to overweight were 0.58 and 0.44, respectively. In conclusion, 10 year weight increase was associated with an increased IFG risk, weight decrease with a decreased risk of IFG in young adults.     

Immediate Effects of an Elastic Knee Sleeve on Frontal Plane Gait Biomechanics in Knee Osteoarthritis

Introduction

Osteoarthritis of the knee affects millions of people. Elastic knee sleeves aim at relieving symptoms. While symptomatic improvements have been demonstrated as a consequence of elastic knee sleeves, evidence for biomechanical alterations only exists for the sagittal plane. We therefore asked what effect an elastic knee sleeve would have on frontal plane gait biomechanics.

Methods

18 subjects (8 women, 10 men) with osteoarthritis of the medial tibiofemoral joint walked over ground with and without an elastic knee sleeve. Kinematics and forces were recorded and joint moments were calculated using an inverse dynamics approach. Conditions with sleeve and without sleeve were compared with paired t-Tests.

Results

With the sleeve, knee adduction angle at ground contact was reduced by 1.9±2.1° (P = 0.006). Peak knee adduction was reduced by 1.5±1.6° (P = 0.004). The first peak knee adduction moment and positive knee adduction impulse were decreased by 10.1% (0.74±0.9 Nm•kg-1; P = 0.002) and 12.9% (0.28±0.3 Nm•s•kg-1; P < 0.004), respectively.

Conclusion

Our study provides evidence that wearing an elastic knee sleeve during walking can reduce knee adduction angles, moments and impulse in subjects with knee osteoarthritis. As a higher knee adduction moment has previously been identified as a risk factor for disease progression in patients with medial knee osteoarthritis, we speculate that wearing a knee sleeve may be beneficial for this specific subgroup.     

Fish Biodiversity of the Vitória-Trindade Seamount Chain,Southwestern Atlantic: An Updated Database

Despite a strong increase in research on seamounts and oceanic islands ecology and biogeography, many basic aspects of their biodiversity are still unknown. In the southwestern Atlantic, the Vitória-Trindade Seamount Chain (VTC) extends ca. 1,200 km offshore the Brazilian continental shelf, from the Vitória seamount to the oceanic islands of Trindade and Martin Vaz. For a long time, most of the biological information available regarded its islands. Our study presents and analyzes an extensive database on the VTC fish biodiversity, built on data compiled from literature and recent scientific expeditions that assessed both shallow to mesophotic environments. A total of 273 species were recorded, 211 of which occur on seamounts and 173 at the islands. New records for seamounts or islands include 191 reef fish species and 64 depth range extensions. The structure of fish assemblages was similar between islands and seamounts, not differing in species geographic distribution, trophic composition, or spawning strategies. Main differences were related to endemism, higher at the islands, and to the number of endangered species, higher at the seamounts. Since unregulated fishing activities are common in the region, and mining activities are expected to drastically increase in the near future (carbonates on seamount summits and metals on slopes), this unique biodiversity needs urgent attention and management.     

Significance of Relative Position of Cellulases in Designer Cellulosomes for Optimized Cellulolysis

Degradation of cellulose is of major interest in the quest for alternative sources of renewable energy, for its positive effects on environment and ecology, and for use in advanced biotechnological applications. Due to its microcrystalline organization, celluose is extremely difficult to degrade, although numerous microbes have evolved that produce the appropriate enzymes. The most efficient known natural cellulolytic system is produced by anaerobic bacteria, such as C. thermocellum, that possess a multi-enzymatic complex termed the cellulosome. Our laboratory has devised and developed the designer cellulosome concept, which consists of chimaeric scaffoldins for controlled incorporation of recombinant polysaccharide-degrading enzymes. Recently, we reported the creation of a combinatorial library of four cellulosomal modules comprising a basic chimaeric scaffoldin, i.e., a CBM and 3 divergent cohesin modules. Here, we employed selected members of this library to determine whether the position of defined cellulolytic enzymes is important for optimized degradation of a microcrystalline cellulosic substrate. For this purpose, 10 chimaeric scaffoldins were used for incorporation of three recombinant Thermobifida fusca enzymes: the processive endoglucanase Cel9A, endoglucanase Cel5A and exoglucanase Cel48A. In addition, we examined whether the characteristic properties of the T. fusca enzymes as designer cellulosome components are unique to this bacterium by replacing them with parallel enzymes from Clostridium thermocellum. The results support the contention that for a given set of cellulosomal enzymes, their relative position within a scaffoldin can be critical for optimal degradation of microcrystaline cellulosic substrates.