Microcystin aids in cold temperature acclimation: Differences between a toxic Microcystis wildtype and non-toxic mutant

For Microcystis aeruginosa PCC 7806, temperature decreases from 26 °C to 19 °C double the microcystin quota per cell during growth in continuous culture. Here we tested whether this increase in microcystin provided M. aeruginosa PCC 7806 with a fitness advantage during colder-temperature growth by comparing cell concentration, cellular physiology, reactive oxygen species damage, and the transcriptomics-inferred metabolism to a non-toxigenic mutant strain M. aeruginosa PCC 7806 ΔmcyB. Photo-physiological data combined with transcriptomic data revealed metabolic changes in the mutant strain during growth at 19 °C, which included increased electron sinks and non-photochemical quenching. Increased gene expression was observed for a glutathione-dependent peroxiredoxin during cold treatment, suggesting compensatory mechanisms to defend against reactive oxygen species are employed in the absence of microcystin in the mutant. Our observations highlight the potential selective advantages of a longer-term defensive strategy in management of oxidative stress (i.e., making microcystin) vs the shorter-term proactive strategy of producing cellular components to actively dissipate or degrade oxidative stress agents

The Occurrence of Microcystin-LR Photoisomerization Products in a New York State Local Lake

The hepatotoxin, Microcystin-LR (MC-LR) is common in New York State lakes. Microcystins undergoes a photochemical isomerization to form several photoisomerization products. These photoisomerization products were generated in the laboratory, characterized by high-field NMR spectroscopy, and an in-house LC-MS microcystin method modified to allow for their detection in natural waters. Lake Neatahwanta (Fulton County, NY) experiences persistent cyanobacteria blooms. Samples were taken weekly from the Lake Neatahwanta during the 2016 and 2017 bloom season to measure the occurrence and concentration of these photoisomerization products in the lake. The products were detected in ~95% of samples and had a strong positive correlation with the in-situ concentration of MC-LR. The proportion of photoisomerization products were higher in dissolved phase than in the particulate phase. There was no significant daily variation observed in a diurnal experiment conducted in both 2016 and 2017. Different analytical method (LC-MS, LC-MSMS and ELISA) were evaluated for their ability to detect these photoisomerization products. This study provides important information on the fate of microcystins in natural waters and the impact of these products on different microcystin detection methods

An Improved Prediction Model Combining Inverse Exponential Smoothing and Markov Chain

On the basis of the triple exponential smoothing prediction model, this paper introduces the reverse prediction idea and establishes the reverse triple exponential smoothing model by setting parameters such as threshold value and iteration times and reasonably correcting its initial value. This method can effectively reduce the error of early prediction value. At the same time, aiming at the problem that the predicting advantage of the reverse triple exponential smoothing model weakens in the later period, Markov theory is introduced to correct its error value, and an improved prediction model combining inverse exponential smoothing and Markov chain is further established. The improved model combines the advantages of index model trend prediction and Markov fluctuation prediction, and the prediction accuracy and stability of the model are significantly improved through case tests

Panax ginseng improves physical recovery and energy utilization on chronic fatigue in rats through the PI3K/AKT/mTOR signalling pathway

AbstractContext Panax ginseng C. A. Meyer (Araliaceae) is a tonic herb used in ancient Asia.Objective This study investigated the antifatigue effect of P. ginseng on chronic fatigue rats.Materials and methods Sprague-Dawley rats were divided into control, model and EEP (ethanol extraction of P. ginseng roots) (50, 100 and 200 mg/kg) groups (n = 8). The rats were subcutaneously handled with loaded swimming once daily for 26 days, except for the control group. The animals were intragastrically treated with EEP from the 15th day. On day 30, serum, liver and muscles were collected, and the PI3K/Akt/mTOR signalling pathway was evaluated.Results The swimming times to exhaust of the rats with EEP were significantly longer than that without it. EEP spared the amount of muscle glycogen, hepatic glycogen and blood sugar under the chronic state. In addition, EEP significantly (p < 0.05) decreased serum triglycerides (1.24 ± 0.17, 1.29 ± 0.04 and 1.20 ± 0.21 vs. 1.58 ± 0.13 mmol/L) and total cholesterol (1.64 ± 0.36, 1.70 ± 0.15 and 1.41 ± 0.19 vs. 2.22 ± 0.19 mmol/L) compared to the model group. Regarding the regulation of energy, EEP had a positive impact on promoting ATPase activities and relative protein expression of the PI3K/Akt/mTOR pathway.Conclusions Our results suggested that EEP effectively relieved chronic fatigue, providing evidence that P. ginseng could be a potential dietary supplement to accelerate recovery from fatigue

Spatial and Temporal Variation in Paralytic Shellfish Toxin Production by Benthic Microseira (Lyngbya) wollei in a Freshwater New York Lake

Butterfield Lake is a mesotrophic lake in New York State where residents and pets have experienced unexplained health issues. Microseira wollei (basionym Lyngbya wollei) was found at two of 15 sites in Butterfield Lake and analyzed for microcystins, anatoxins, cylindrospermopsins, and paralytic shellfish poisoning toxins (PSTs). Only PSTs and trace levels of anatoxin-a were detected in these samples. This is the first published report of PSTs within a New York State lake. To evaluate the environmental and temporal drivers leading to the observed toxicity, PST content at the two sites was examined in detail. There were distinct differences in the total PST content, filament nutrient, filament chlorophyll, and relationship to environmental drivers between the sites, as well as distinct differences in the total PST content measured using different analytical techniques. A multivariate model containing site, temperature, and filament chlorophyll explained 85% of the variation in PSTs observed over the growing season. This work emphasizes the importance of proper site selection and choice of analytical technique in the development of monitoring programs to protect lake users from the occurrence of benthic cyanobacteria toxins

Optimization of Sintering Time and Holding Time for 3D Printing of Fe-Based Metallic Glasses

Fe-based metallic glasses are amorphous alloys with high strength, high hardness, and excellent corrosion resistance; however, the immaturity of processing methods has prevented their wide application in industrial production. Fe-based metallic glass parts were manufactured employing pneumatic injection additive manufacturing in this study. An evenly dispersed and stable Fe-based metallic glass powder slurry with a solids content of 50% was prepared firstly. Then the Fe-based metallic glass parts were printed. The printed parts were dried, debinded, and sintered for strengthening. The deformations of the printed parts and sintered parts relative to the original model were then analyzed by a 3D scanning reconstruction method. The slightly average bulging and sunken deformation of the printed parts and sintered parts confirmed the good printing accuracy of the pneumatic injection manufacture system. The effects of the sintering temperature and holding time on the properties of the sintered parts were studied. For a sintering temperature of 580 &deg;C and holding time of 1 h, the surface quality of the sintered parts was better. The sintering of 3D-printed Fe-based metallic glass parts was preliminarily realized in this study, and the feasibility of preparing Fe-based metallic glass using pneumatic injection additive manufacture was verified

Microcystin aids in photo-acclimation during prolonged cold stress treatment in Microcystis aeruginosa strain PCC7806

Microcystis aeruginosa PCC7806 has been shown to increase toxin production in response to prolonged cold stress. To test whether this increase in toxin production is a beneficial adaptation that aids in cold fitness, the non-toxic mutant Microcystis aeruginosa PCC 7806 ΔmcyB was grown in duplicate chemostat cultures alongside chemostats containing the wildtype isolate. Strains reached steady-state at 26℃, then were subjected to an 11-day shift to 19℃, followed by a reversion back to 26℃. Throughout the experimental period, samples were collected to measure cell abundance, excitation pressure, effective quantum yield, microcystin production, reactive oxygen species (ROS) formation, and for RNA-seq analyses. During the 19℃ period, the mutant experienced elevated excitation pressure and ROS formation relative to the wildtype strain. Microcystin quota doubled in the wildtype strain by day 7 of the 19℃ treatment, followed by decreased effective quantum yields 24 h later. This was not observed in the mutant strains. Both mutant and wildtype populations began to recover after 8 days at 19℃. Microcystin did not aid in growth recovery during cold stress, although it seemed to play a part in the photo-acclimatory process based on excitation pressure and quantum yield readings

Reliability of a portable device for quantifying tone and stiffness of quadriceps femoris and patellar tendon at different knee flexion angles.

The reliability of MyotonPRO that can monitor the mechanical properties of tissues is still unclear. This study aimed to analyze the within-day inter-operator and between-day intra-operator reliability of MyotonPRO for assessing tone and stiffness of quadriceps femoris and patellar tendon at different knee angles. The tone and stiffness of healthy participants (15 males and 15 females, aged 24.7±1.6 years) in the supine and resting position were measured using the MyotonPRO device. The measurements were quantified at 0°, 30°, 60°, and 90° of knee flexion. The intraclass correlation coefficient (ICC), standard error of measurement (SEM), and minimal detectable change (MDC) were calculated and a Bland-Altman analysis was conducted to estimate reliability. The results indicated excellent inter-operator reliability (ICC > 0.78) and good to excellent intra-operator reliability (ICC > 0.41). The inter-operator SEM measurements ranged between 0.1-0.9 Hz and 3.8-37.9 N/m, and intra-operator SEM ranged between 0.5-1.3 Hz and 7.9-52.0 N/m. The inter-operator MDC ranged between 0.3-2.5 Hz and 10.5-105.1 N/m, and intra-operator SEM ranged between 1.1-3.3 Hz and 21.9-144.1 N/m. The agreement of inter-operator was better than that of intra-operator. The study concluded that MyotonPRO is a reliable device to detect the tone and stiffness of quadriceps femoris and patellar tendon