The present study aimed to investigate the effects of eccentric treadmill exercise on adaptive hypertrophy of skeletal muscle in rats. Thirty-two 3-month-old Sprague Dawley (SD) rats were selected and randomly assigned to one of the four groups based on their body weights: 2-week quiet control group (2C), 2-week downhill running exercise group (2E), 4-week quiet control group (4C), and 4-week downhill running exercise group (4E). The downhill running protocol for rats in the exercise groups involved slope of -16°, running speed of 16 m/min, training duration of 90 min, and 5 training sessions per week. Twenty-four hours after the final session of training, all the four groups of rats underwent an exhaustion treadmill exercise. After resting for 48 h, all the rats were euthanized and their gastrocnemius muscles were harvested for analysis. HE staining was used to measure the cross-sectional area (CSA) and diameter of muscle fibers. Transmission electron microscope was used to observe the ultrastructural changes in muscle fibers. Purithromycin surface labeling translation method was used to measure protein synthesis rate. Immunofluorescence double labeling was used to detect the colocalization levels of lysosomal-associated membrane protein 2 (Lamp2)-leucyl-tRNA synthetase (LARS) and Lamp2-mammalian target of rapamycin (mTOR). Western blot was used to measure the protein expression levels of myosin heavy chain (MHC) IIb and LARS, as well as the phosphorylation levels of mTOR, p70 ribosomal protein S6 kinase (p70S6K), and eukaryotic translation initiation factor 4E binding protein 1 (4E-BP1). The results showed that, compared with the 2C group rats, the 2E group rats showed significant increases in wet weight of gastrocnemius muscle, wet weight/body weight ratio, running distance, running time, pre- and post-exercise blood lactate levels, myofibrillar protein content, colocalization levels of Lamp2-LARS and Lamp2-mTOR, and LARS protein expression. Besides these above changes, compared with the 4C group, the 4E group further exhibited significantly increased fiber CSA, fiber diameter, protein synthesis rate, and phosphorylation levels of mTOR, p70S6K, and 4E-BP1. Compared with the quiet control groups, the exercise groups exhibited ultrastructural damage of rat gastrocnemius muscle, which was more pronounced in the 4E group. These findings suggest that eccentric treadmill exercise may promote mTOR translocation to lysosomal membrane, activating mTOR signaling via up-regulating LARS expression. This, in turn, increases protein synthesis rate through the mTOR-p70S6K-4E-BP1 signaling pathway, promoting protein deposition and inducing adaptive skeletal muscle hypertrophy. Although the ultrastructural changes of skeletal muscle are more pronounced, the relatively long training cycles during short-term exercise periods have a more significant effect on promoting gastrocnemius muscle protein synthesis and adaptive hypertrophy.
Animals ; Rats, Sprague-Dawley ; Physical Conditioning, Animal/physiology* ; Rats ; Muscle, Skeletal/metabolism* ; TOR Serine-Threonine Kinases/metabolism* ; Male ; Hypertrophy ; Adaptation, Physiological/physiology* ; Adaptor Proteins, Signal Transducing/metabolism* ; Ribosomal Protein S6 Kinases, 70-kDa/metabolism* ; Intracellular Signaling Peptides and Proteins

The balance between growth and defense in response to nearby or canopy shading in heliotropic plants has been deeply understood. However, the adaptive traits developed by shade-tolerant plants through long-term evolution remain unclear. In this study, the typical shade-tolerant medicinal plant Anoectochilus roxburghii was used as the experimental material.(1) Different planting densities were set, including 8 cm(row spacing) × 8 cm(plant spacing), 6 cm × 6 cm, 4 cm × 4 cm, and 2 cm × 2 cm, to monitor the individual plant responses to nearby shading.(2) Different light environments, including blue light∶red light=3∶2(B3R2), blue light∶red light∶far-red light=3∶2∶1(B3R2FR1), blue light∶red light∶far-red light=3∶2∶2(B3R2FR2), and blue light∶red light∶far-red light=3∶2∶4(B3R2FR4), were set to monitor the morphological and physiological changes in plants in response to actual shading conditions. The results showed that:(1) Moderate increases in planting density helped optimize morphological traits such as stem diameter and leaf area. This not only slightly increased biomass but also significantly improved SOD activity in both leaves and stems, as well as lignin content in stems, thereby enhancing the plant's defense capabilities.(2) Increasing the far-red light in the light environment negatively regulated the plant height of A. roxburghii, which was contrary to the typical shade-avoidance response observed in heliotropic plants. However, it significantly enhanced SOD and POD activity in both stems and leaves, as well as lignin content in stems. Furthermore, it reduced the incidence and disease index of stalk rot, effectively defending against biotic stress. Therefore, the shade-tolerant plant A. roxburghii has specific adaptive strategies for shading conditions. Reasonable dense planting or light environment modulation can synergistically improve yield, medicinal quality, and resistance of A. roxburghii. This study provides a theoretical foundation and technical support for optimizing the regional deployment and cultivation strategies of ecological planting for Chinese medicinal materials.
Orchidaceae/genetics* ; Light ; Plant Leaves/physiology* ; Sunlight ; Adaptation, Physiological/radiation effects* ; Plant Proteins/genetics*

OBJECTIVES: This study aims to investigate the impact of glutathione S-transferase (GST) on the environmental adaptability of Streptococcus mutans (S. mutans). METHODS: A GST knockout strain ΔgsT was constructed. Transcriptomic sequencing was performed to analyze the gene expression differences between the wild-type S. mutans UA159 and its GST knockout strain ΔgsT. Comprehensive functional assessments, including acid tolerance assays, hydrogen peroxide challenge assays, nutrient limitation growth assays, and fluorescence in situ hybridization, were conducted to evaluate the acid tolerance, antioxidant stress resistance, growth kinetics, and interspecies competitive ability of ΔgsT within plaque biofilms. RESULTS: Compared with the wild-type S. mutans, 198 genes in ΔgsT were significantly differentially expressed and enriched in pathways related to metabolism, stress response, and energy homeostasis. The survival rate of ΔgsT in acid tolerance assays was markedly reduced (P<0.01). After 15 min of hydrogen peroxide challenge, the survival rate of ΔgsT decreased to 38.12% (wild type, 71.75%). Under nutrient-limiting conditions, ΔgsT exhibited a significantly lower final OD₆₀₀ value than the wild-type strain (P<0.05). In the biofilm competition assays, the proportion of S. mutans ΔgsT in the mixed biofilm (8.50%) was significantly lower than that of the wild type (16.89%) (P<0.05). CONCLUSIONS GST enhances the acid resistance, oxidative stress tolerance, and nutrient adaptation of S. mutans by regulating metabolism-related and stress response-related genes.
Streptococcus mutans/enzymology* ; Biofilms ; Glutathione Transferase/physiology* ; Adaptation, Physiological ; Hydrogen Peroxide/pharmacology* ; Gene Expression Regulation, Bacterial ; Oxidative Stress ; Metabolic Reprogramming

Adaptation, Physiological ; Adenosine Monophosphate ; administration & dosage ; analogs & derivatives ; pharmacology ; therapeutic use ; Administration, Intranasal ; Alanine ; administration & dosage ; analogs & derivatives ; pharmacology ; therapeutic use ; Animals ; Betacoronavirus ; genetics ; physiology ; Chlorocebus aethiops ; Coronavirus Infections ; drug therapy ; virology ; Disease Models, Animal ; Female ; Host Specificity ; genetics ; Lung ; pathology ; virology ; Male ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; Mutation, Missense ; Nasal Mucosa ; virology ; Pandemics ; Pneumonia, Viral ; drug therapy ; virology ; RNA, Viral ; administration & dosage ; genetics ; Turbinates ; virology ; Vero Cells ; Viral Load ; Virus Replication

We wished to select a cold-adapted genotype G1P[8] ZTR-68 rotavirus (China southwest strain) in MA104 cells for possible use as a live vaccine. ZTR-68 was recovered originally from children with diarrhea. The virus was cultivated at 37 degrees C at the first passage. Then, the cultivation temperature was decreased stepwise by 3 degrees C per eight passages. In total, the virus was passaged 32 times, and cultivation was terminated at 28 degrees C. Biological characteristics of the virus were analyzed during serial passages. There was no difference between the migration patterns of genomic dsRNA segments according to polyacrylamide gel electrophoresis of original and cold-adapted viruses. Infectious and red cell-agglutination titers of cold-adapted virus were lower than those of the parent virus. Also, the virus formed small-size plaques with irregular shapes at 31 degrees C and 28 degrees C. These results suggested that a genetically stable attenuated virus can be obtained through serial cold-adapted passages. Thus, an alternative strategy is provided by cold-adaption for development of attenuated live rotavirus vaccines.
Adaptation, Physiological ; China ; Cold Temperature ; Diarrhea ; virology ; Female ; Genotype ; Humans ; Infant ; Male ; Rotavirus ; genetics ; growth & development ; isolation & purification ; physiology ; Serial Passage ; Virus Cultivation ; Virus Replication

Nowadays, for gait instability phenomenon, many researches have been carried out at home and abroad. However, the relationship between plantar pressure and gait parameters in the process of balance adjustment is still unclear. This study describes the human body adaptive balance reaction during slip events on slippery level walk by plantar pressure and gait analysis. Ten healthy male subjects walked on a level path wearing shoes with two contrastive contaminants (dry, oil). The study collected and analyzed the change rule of spatiotemporal parameters, plantar pressure parameters, vertical ground reaction force (VGRF), etc. The results showed that the human body adaptive balance reaction during slip events on slippery level walk mainly included lighter touch at the heel strikes, tighter grip at the toe offs, a lower velocity, a shorter stride length and longer support time. These changes are used to maintain or recover body balance. These results would be able to explore new ideas and provide reference value for slip injury prevention, walking rehabilitation training design, research and development of walking assistive equipments, etc.
Adaptation, Physiological ; Foot ; Gait ; Humans ; Male ; Postural Balance ; physiology ; Pressure ; Reference Values ; Walking

As human beings ascend to high altitude, a number of reactions may occur against hypoxic injuries. These hypoxic responses are related to intake, transportation and utility of the oxygen. As a crucial subcellular organelle of oxygen utility, mitochondrion is a central link of high altitude acclimatization, adaptation and mountain sicknesses. In this review, we discussed the recent advances in researches on hypoxic mitochondrial responses at high altitude.
Adaptation, Physiological ; Altitude ; Altitude Sickness ; Animals ; Humans ; Hypoxia ; Mitochondria ; pathology ; Oxygen ; physiology

Long-term endurance training or physical activity has been confirmed not only to improve physical performance, but to bring about an obvious beneficial effect on human health; however, the mechanism of this effect is not clear. The most studied health adaptations in skeletal muscle response to endurance exercise are increased muscle glycogen level and insulin sensitivity, fiber type transformation toward oxidative myofibers, and increased mitochondrial content/function. Mitochondria are dynamic organelles in eukaryotic cells critical in physical performance and disease occurrence. The mitochondrial life cycle spans biogenesis, maintenance, and clearance. Exercise training may promote each of these processes and confer positive impacts on skeletal muscle contractile and metabolic functions. This review focused on the regulation of these processes by endurance exercise and discussed its potential benefits in health and disease. We presented evidence suggesting that exercise training potentiates not only the biogenesis of mitochondria but also the removal of old and unhealthy mitochondria through mitochondrial quality control.
Adaptation, Physiological ; Exercise ; Humans ; Mitochondria ; physiology ; Muscle Contraction ; Muscle, Skeletal ; physiology

In order to lower the cost of lipid production of microalgae and reduce greenhouse gas emissions, microalgae Chlorococcum alkaliphilus MC-1 with the characteristics of rapid pH drift and high pH adaptability, was cultivated with bubbling of flue gas. The experiment was first performed in the photobioreactor (15 L) in three groups (control group, CO2 group and flue gas group), then, in the open raceway pond (24 m2). The adaptability of microalgae MC-1 to the cultivation with flue gas was studied. The results showed that the maximum biomass concentration, growth rate, total lipid content and CO2 fixation rate were (1.02+/-0.07) g/L, (0.12+/-0.02) g/(L.d), (37.84+/-0.58)% and (0.20+/-0.02) g/(L.d) in the photobioreactor treated with flue gas, 36%, 33.33%, 15.34% and 33.33% higher than those of the CO2 group, respectively. In the open raceway pond with aeration of flue gas, the maximum biomass concentration, growth rate, total lipid content and CO2 fixation rate were 147.40 g/m2, 14.73 g/(m2.d), 35.72% and 24.01 g/(m2.d), respectively, which were similar to the cultivation with pure CO2. The toxic heavy metal contents (Pb, As, Cd and Cr) in the biomass of MC-1 treated with flue gas were all below the legal limits. Additionally, the absorptive effect of CO2, NO and SO2 were determined. In the photobioreactor and open raceway pond, the average absorption ratios of these gases were all higher than previous studies. Therefore, our study showed that MC-1 can adapt to the cultivation with flue gas, and it is feasible to enlarge the outdoor cultivation of MC-1 for lipid production coupling with emissions reduction of flue gas.
Adaptation, Physiological ; physiology ; Carbon Dioxide ; chemistry ; Chlorophyta ; classification ; growth & development ; physiology ; Culture Media ; metabolism ; Culture Techniques ; methods ; Gases ; chemistry ; Microalgae ; classification ; growth & development ; physiology ; Nitric Oxide ; chemistry ; Sulfur Dioxide ; chemistry

OBJECTIVETo study the protection of stress protein calreticulin (CRT) in rat skeletal muscle during the adaptation mechanism of calmodulin in the course of heat treatment.

METHODSIncreased heat treatment program would be applied, 40 SD rats were randomly divided into the quiet control group C (n = 8) and heat-treated group H (n = 32), then the heat treatment group would be divided into immediately group (H1), 24-hour post-heat treatment group (H2), 48 -hour post-heat treatment group (H3) and six days post-heat treatment group (H4) (n = 8).

RESULTSAfter heat treatment, the Ca(2+)-ATP activity in rat skeletal muscle sarcoplasmic reticulum in H2 group reached the highest value compared with that in the quiet control group C (P < 0.01), and the value in H1 group showed significant differences compared with control group C (P < 0.05); The Ca(2+)-ATP activity in mitochondrial had the highest value in H1 group, compared with the quiet control group C (P < 0.05), while the Ca2+ concentration in rat skeletal muscle sarcoplasmic reticulum had the highest in group H2, followed by H1 group, both showing significant difference compared with the quiet control group (P < 0.05); The Ca2+ concentration in mitochondrial was high in H1 and H2 group than that of the quiet control group C, and the value in H3 and H4 group was lower than that of the quiet control group C, which had no difference; After heat treatment, the expression of stress proteins of CRT from H1, H2 and H3 group in rat skeletal muscle increased significantly compared with quiet group C.

CONCLUSIONIn the process of increased heat treatment, calreticulin played the regulatory role on the imbalance of calcium homeostasis in skeletal muscle cells, and the adaptation protection from the thermal stimulation could have the very good effect on muscle.

Adaptation, Physiological ; Animals ; Calcium ; metabolism ; Calreticulin ; physiology ; Heat Stress Disorders ; metabolism ; physiopathology ; Male ; Mitochondria ; metabolism ; Muscle, Skeletal ; metabolism ; physiology ; Rats ; Rats, Sprague-Dawley ; Sarcoplasmic Reticulum Calcium-Transporting ATPases ; metabolism