Climate–ecosystem modelling made easy: The Land Sites Platform

Dynamic Global Vegetation Models (DGVMs) provide a state-of-the-art process-based approach to study the complex interplay between vegetation and its physical environment. For example, they help to predict how terrestrial plants interact with climate, soils, disturbance and competition for resources. We argue that there is untapped potential for the use of DGVMs in ecological and ecophysiological research. One fundamental barrier to realize this potential is that many researchers with relevant expertize (ecology, plant physiology, soil science, etc.) lack access to the technical resources or awareness of the research potential of DGVMs. Here we present the Land Sites Platform (LSP): new software that facilitates single-site simulations with the Functionally Assembled Terrestrial Ecosystem Simulator, an advanced DGVM coupled with the Community Land Model. The LSP includes a Graphical User Interface and an Application Programming Interface, which improve the user experience and lower the technical thresholds for installing these model architectures and setting up model experiments. The software is distributed via version-controlled containers; researchers and students can run simulations directly on their personal computers or servers, with relatively low hardware requirements, and on different operating systems. Version 1.0 of the LSP supports site-level simulations. We provide input data for 20 established geo-ecological observation sites in Norway and workflows to add generic sites from public global datasets. The LSP makes standard model experiments with default data easily achievable (e.g., for educational or introductory purposes) while retaining flexibility for more advanced scientific uses. We further provide tools to visualize the model input and output, including simple examples to relate predictions to local observations. The LSP improves access to land surface and DGVM modelling as a building block of community cyberinfrastructure that may inspire new avenues for mechanistic ecosystem research across disciplines.     

Effects of chronic fluorosis on electrocardiogram in sheep

This study was carried out to evaluate the effects of chronic fluorosis by means of the electrocardiograms in sheep. Ten sheep with fluorosis living around a volcanic mountain (Tendürek Mount) in East Anatolia in Turkey and 10 healthy sheep were used. Leads I, II, III, aVR, aVL, aVF, V₂, V₄, and V₁₀ were recorded in the electrocardiographs of the sheep. All waves were seen in all derivations. The P-Q interval was significantly (p<0.05) prolonged and sinus bradycardia was observed in the sheep with fluorosis. As a result of this, the number of heart beats was decreased significantly (p<0.05); that is, the number of heart beats was 110±15 in the control group and 75±10 in sheep with fluorosis.     

Effects of Calcium Supplementation on Glucose and Insulin Levels of Athletes at Rest and After Exercise

This study was performed to determine how the calcium supplementation for a 4-week period affects the glucose and insulin levels at rest and at exhaustion in athletes. This is a 4-week study performed on 30 healthy subjects varying between 18 and 22 ages. Subjects were separated into three groups: first group (group supplemented with calcium, sedentary group), second group (calcium supplementations + exercise group), and third group (training group). Glucose and insulin parameters of the groups were measured four times, at rest and exhaustion in the beginning of the research and at rest and exhaustion after the end of 4 weeks application period. Exhaustion measurements both before and after the supplementations significantly decreased in compared to rest measurements in terms of insulin (p < 0.05). Significant difference was not determined in the glucose values of groups. In terms of glucose, values increased in all of the three groups occurred with exercise both before and after the supplementation by exercise and exhaustion (p < 0.05). The results of our study indicate that calcium gluconate supplementations for 4 weeks in sedentary subjects and athletes did not significantly affect plasma insulin levels at rest and exhaustion. However, glucose levels were affected by calcium supplementation and exhausting exercise in athletes.     

The effects of magnesium supplementation on thyroid hormones of sedentars and Tae-Kwon-Do sportsperson at resting and exhaustion

The effect of magnesium on thyroid hormones of sedentars and sportsperson in Tae-Kwon-Do, has been investigated in a 4-weeks training program. Group 1 consisted of sedentars receiving 10 mg/kg/day Mg for 4 weeks. Group 2 consisted of subjects receiving magnesium (Mg) supplement and practicing Tae-Kwon-Do for 90-120 min/day, for five days a week. Group 3 consisted of subjects practicing Tae-Kwon-Do but receiving Mg supplements. TSH levels increased with training and Mg supplementation (p<0.05). Mg increased FT3 values. (p<0.05). TT3 values of groups reduced in all groups (p<005). After supplementation, group 1 had higher TT4 values than groups 1 and 3 and the group 2 had higher TT4 values than the third group (p<005). Results of this research show that training until exhaustion causes reduction in thyroid hormone activity in sedentars and sportsperson. It has been established that Mg supplementation however, prevents reduction in thyroid hormone activity in sedentars and sportsperson.     

The effect of magnesium supplementation on lactate levels of sportsmen and sedanter

This study was performed to assess how magnesium supplementation affects plasma lactate levels at rest and exhaustion in sportsmen and sedentary. Research was performed on 30 healthy subjects varying between 18-22 years of age for a four-week period. Subjects were separated into 3 groups: Group 1; sedentary taking magnesium supplementation only (10 mg/kg/day) (Mg + S), Group 2; subjects magnesium supplemented + training 90-120 min 5 days a week (Mg + Training), Group 3; training 90-120 min 5 days a week. Lactate levels of the groups were measured 4 times; at rest and exhaustion in the beginning of the research and after the end of the research. At the end of the research, exhaustion measurements both before and after supplement were found significantly higher than rest measurements in terms of lactate levels (p < 0.05). An important decrease was determined in the lactate levels of the 1st and 2nd groups when compared to their first measurements (p < 0.05). The results of this research indicate that lactate increases with exhaustion. However, magnesium supplement may positively affect performance of sportsmen by decreasing their lactate levels.     

L-Cysteine influx and efflux: a possible role for red blood cells in regulation of redox status of the plasma

The objective of this study was to investigate if erythrocytes play a role in the maintenance of redox homeostasis of the plasma. Thus, we studied L-cysteine efflux and influx in vitro in human erythrocytes. In the present study, we exposed the erythrocytes to different concentrations of L-cysteine and then measured the intracellular free -SH concentrations. Erythrocytes treated in the same manner were later utilized for the cysteine efflux studies. The effect of temperature on the influx and the efflux processes were also evaluated. Change in the free -SH content of the buffer was evaluated as a measure for the presence of an efflux process. The effects of free -SH depletion on L-cysteine transport is also investigated. We also determined the rate of L-cysteine efflux in the presence and absence of buthionine sulfoximine (BSO) in erythrocytes that are pretreated with 1-chloro-2,4-dinitro benzene, a glutathione (GSH) depletory. Our L-cysteine influx studies demonstrated that erythrocytes can respond to increases in L-cysteine concentration in the extracellular media and influx L-cysteine in a concentration-dependent manner. Free -SH concentrations in erythrocytes treated with 1 mM L-cysteine reached to 1.64 +/- 0.06 mM in 1 h whereas this concentration reached to 4.30 +/- 0.01 mM in 10 mM L-cysteine treated erythrocytes. The L-cysteine efflux is also determined to be time-and concentration-dependent. Erythrocytes that are pretreated with higher L-cysteine concentrations displayed a higher efflux process. Outside concentration of free -SH in 1 mM L-cysteine pretreated erythrocytes reached to 0.200 +/- 0.005 mM in 1 h whereas this concentration reached to 1.014 +/- 0.002 with 10 mM L-cysteine pretreated erythrocytes. Our results also indicate that the rate of inward and outward transport of L-cysteine is affected by the oxidative status of the erythrocytes. When GSH is depleted and GSH synthesis is blocked, the L-cysteine uptake and the efflux processes are significantly decreased. Depending on our results, it could be concluded that erythrocytes play a role in the regulation of the plasma redox status and intracellular level of GSH determines the rate of the L-cysteine efflux.     

Protein kinase D1 is essential for contraction-induced glucose uptake but is not involved in fatty acid uptake into cardiomyocytes

Increased contraction enhances substrate uptake into cardiomyocytes via translocation of the glucose transporter GLUT4 and the long chain fatty acid (LCFA) transporter CD36 from intracellular stores to the sarcolemma. Additionally, contraction activates the signaling enzymes AMP-activated protein kinase (AMPK) and protein kinase D1 (PKD1). Although AMPK has been implicated in contraction-induced GLUT4 and CD36 translocation in cardiomyocytes, the precise role of PKD1 in these processes is not known. To study this, we triggered contractions in cardiomyocytes by electric field stimulation (EFS). First, the role of PKD1 in GLUT4 and CD36 translocation was defined. In PKD1 siRNA-treated cardiomyocytes as well as cardiomyocytes from PKD1 knock-out mice, EFS-induced translocation of GLUT4, but not CD36, was abolished. In AMPK siRNA-treated cardiomyocytes and cardiomyocytes from AMPKα2 knock-out mice, both GLUT4 and CD36 translocation were abrogated. Hence, unlike AMPK, PKD1 is selectively involved in glucose uptake. Second, we analyzed upstream factors in PKD1 activation. Cardiomyocyte contractions enhanced reactive oxygen species (ROS) production. Using ROS scavengers, we found that PKD1 signaling and glucose uptake are more sensitive to changes in intracellular ROS than AMPK signaling or LCFA uptake. Furthermore, silencing of death-activated protein kinase (DAPK) abrogated EFS-induced GLUT4 but not CD36 translocation. Finally, possible links between PKD1 and AMPK signaling were investigated. PKD1 silencing did not affect AMPK activation. Reciprocally, AMPK silencing did not alter PKD1 activation. In conclusion, we present a novel contraction-induced ROS-DAPK-PKD1 pathway in cardiomyocytes. This pathway is activated separately from AMPK and mediates GLUT4 translocation/glucose uptake, but not CD36 translocation/LCFA uptake.