Time-Dependent Effects of Anesthetic Isoflurane on Reactive Oxygen Species Levels in HEK-293 Cells

The inhalation anesthetic isoflurane has been reported to induce caspase activation and apoptosis, which may lead to learning and memory impairment. However, the underlying mechanisms of these effects are largely unknown. Isoflurane has been shown to induce elevation of cytosol calcium levels, accumulation of reactive oxygen species (ROS), opening of the mitochondrial permeability transition pore, reduction in mitochondria membrane potential, and release of cytochrome c. The time course of these effects, however, remains to be determined. Therefore, we performed a pilot study to determine the effects of treatment with isoflurane for various times on ROS levels in HEK-293 cells. The cells were treated with 2% isoflurane plus 21% O2 and 5% CO2 for 15, 30, 60, or 90 min. We then used fluorescence imaging and microplate fluorometer to detect ROS levels. We show that 2% isoflurane for 60 or 90 min, but not 15 or 30 min, induced ROS accumulation in the cells. These data illustrated that isoflurane could cause time-dependent effects on ROS levels. These findings have established a system to further determine the time course effects of isoflurane on cellular and mitochondria function. Ultimately, the studies would elucidate, at least partially, the underlying mechanisms of isoflurane-induced cellular toxicity

Identification of drought-responsive microRNAs in Medicago truncatula by genome-wide high-throughput sequencing

<p>Abstract</p> <p>Background</p> <p>MicroRNAs (miRNAs) are small, endogenous RNAs that play important regulatory roles in development and stress response in plants by negatively affecting gene expression post-transcriptionally. Identification of miRNAs at the global genome-level by high-throughout sequencing is essential to functionally characterize miRNAs in plants. Drought is one of the common environmental stresses limiting plant growth and development. To understand the role of miRNAs in response of plants to drought stress, drought-responsive miRNAs were identified by high-throughput sequencing in a legume model plant, <it>Medicago truncatula</it>.</p> <p>Results</p> <p>Two hundreds eighty three and 293 known miRNAs were identified from the control and drought stress libraries, respectively. In addition, 238 potential candidate miRNAs were identified, and among them 14 new miRNAs and 15 new members of known miRNA families whose complementary miRNA*s were also detected. Both high-throughput sequencing and RT-qPCR confirmed that 22 members of 4 miRNA families were up-regulated and 10 members of 6 miRNA families were down-regulated in response to drought stress. Among the 29 new miRNAs/new members of known miRNA families, 8 miRNAs were responsive to drought stress with both 4 miRNAs being up- and down-regulated, respectively. The known and predicted targets of the drought-responsive miRNAs were found to be involved in diverse cellular processes in plants, including development, transcription, protein degradation, detoxification, nutrient status and cross adaptation.</p> <p>Conclusions</p> <p>We identified 32 known members of 10 miRNA families and 8 new miRNAs/new members of known miRNA families that were responsive to drought stress by high-throughput sequencing of small RNAs from <it>M. truncatula</it>. These findings are of importance for our understanding of the roles played by miRNAs in response of plants to abiotic stress in general and drought stress in particular.</p

Plant 3D Chromatin Organization: Important Insights from Chromosome Conformation Capture Analyses of the Last 10 Years

Over the past few decades, eukaryotic linear genomes and epigenomes have been widely and extensively studied for understanding gene expression regulation. More recently, the three-dimensional (3D) chromatin organization was found to be important for determining genome functionality, finely tuning physiological processes for appropriate cellular responses. With the development of visualization techniques and chromatin conformation capture (3C)-based techniques, increasing evidence indicates that chromosomal architecture characteristics and chromatin domains with different epigenetic modifications in the nucleus are correlated with transcriptional activities. Subsequent studies have further explored the intricate interplay between 3D genome organization and the function of interacting regions. In this review, we summarize spatial distribution patterns of chromatin, including chromatin positioning, configurations and domains, with a particular focus on the effect of a unique form of interaction between varieties of factors that shape the 3D genome conformation in plants. We further discuss the methods, advantages and limitations of various 3C-based techniques, highlighting the applications of these technologies in plants to identify chromatin domains, and address their dynamic changes and functional implications in evolution, and adaptation to development and changing environmental conditions. Moreover, the future implications and emerging research directions of 3D genome organization are discussed

Metabolic response of soybean leaves induced by short-term exposure of ozone

The ever-increasing ozone (O-3) concentration has led to reduced production and altered quality of soybean. Abundant reports have explored the damage mechanisms of O-3 on soybean. However, how the elevated O-3 affects metabolite profiling of soybean remains to be poorly understood. Here, we compare the metabolic profile of soybean leaves under charcoal filtered air (CF, <20 ppb) and short-term elevated O-3 concentration (EO, 100 ppb). High level of O-3 affects metabolites for the tricarbonic acid (TCA) cycle, reactive oxygen species, cell wall composition and amino acids. Significantly, jasmonic acid-related metabolite promoting stomata closure is highly induced with 125-fold change. Furthermore, O-3 fumigation alters the expression of genes contributing to the biosynthesis of certain metabolites in TCA cycle. Together, these findings identify a wide range of changed metabolites in response to O-3 pollution. Our results pave the way for the genetic improvement of soybean to adapt to O-3 pollution to maintain stable yields

The Adaptive Mechanism of Plants to Iron Deficiency via Iron Uptake, Transport, and Homeostasis

Iron is an essential element for plant growth and development. While abundant in soil, the available Fe in soil is limited. In this regard, plants have evolved a series of mechanisms for efficient iron uptake, allowing plants to better adapt to iron deficient conditions. These mechanisms include iron acquisition from soil, iron transport from roots to shoots, and iron storage in cells. The mobilization of Fe in plants often occurs via chelating with phytosiderophores, citrate, nicotianamine, mugineic acid, or in the form of free iron ions. Recent work further elucidates that these genes&#8217; response to iron deficiency are tightly controlled at transcriptional and posttranscriptional levels to maintain iron homeostasis. Moreover, increasing evidences shed light on certain factors that are identified to be interconnected and integrated to adjust iron deficiency. In this review, we highlight the molecular and physiological bases of iron acquisition from soil to plants and transport mechanisms for tolerating iron deficiency in dicotyledonous plants and rice

CIPK23 is involved in iron acquisition of Arabidopsis by affecting ferric chelate reductase activity

Iron deficiency is one of the major limiting factors affecting quality and production of crops in calcareous soils. Numerous signaling molecules and transcription factors have been demonstrated to play a regulatory role in adaptation of plants to iron deficiency. However, the mechanisms underlying the iron deficiency-induced physiological processes remain to be fully dissected. Here, we demonstrated that the protein kinase CIPK23 was involved in iron acquisition. Lesion of CIPK23 rendered Arabidopsis mutants hypersensitive to iron deficiency, as evidenced by stronger chlorosis in young leaves and lower iron concentration than wild-type plants under iron-deficient conditions by down-regulating ferric chelate reductase activity. We found that iron deficiency evoked an increase in cytosolic Ca2+ concentration and the elevated Ca2+ would bind to CBL1/CBL9, leading to activation of CIPK23. These novel findings highlight the involvement of calcium-dependent CBL-CIPK23 complexes in the regulation of iron acquisition. Moreover, mutation of CIPK23 led to changes in contents of mineral elements, suggesting that CBL-CIPK23 complexes could be as nutritional sensors to sense and regulate the mineral homeostasis in Arabisopsis. (C) 2016 Elsevier Ireland Ltd. All rights reserved

Calmodulin-like gene MtCML40 is involved in salt tolerance by regulating MtHKTs transporters in Medicago truncatula

Calcium (Ca2+) is a universal messenger mediating numerous physiological processes in responses to developmental and environmental cues in plant cells. Calmodulin (CaM) and calmodulin-like proteins (CMLs) are important plant Ca2+ sensors involved in decoding Ca2+ signatures to execute downstream physiological responses. Despite the involvements of CML proteins in the regulation of developmental processes, little is known about the function of CMLs in response to abiotic stresses in plants. To characterize CML proteins, we isolated and functionally characterized a gene encoding a CML protein from legume model plant Medicago truncatula, referred to as MtCML40. The MtCML40 belonged to subgroup VI of CML family. Expression of MtCML40 was up-regulated by salt, cold and osmotic stress as well as ABA treatment, suggesting a role of MtCML40 in abiotic stress. To test this hypothesis, we generated MtCML40 overexpressing transgenic lines in M. truncatula. Overexpression of MtCML40 rendered seed germination more sensitive to salt stress as evidenced by greater inhibition of seed germination of transgenic lines than wild-type seeds when exposed to NaCI, while seed germination of WT and transgenic lines was comparable under control conditions. In addition to seed germination, exposure to salt stress led to greater inhibition of shoot and root growth, reduction in chlorophyll and carotenoid concentrations and photosynthetic rates in the transgenic lines than WT plants, suggesting a negative regulation of salt tolerance by MtCML40. The greater accumulation of Na+ in shoots of transgenic lines may account for the greater sensitivity to salt stress. We further found that overexpression of MtCML40 resulted in down-regulation of MtHKT1;1 and MtlIKT1;2 that encoded proteins associated with removal of Na+ from shoots. Taken together, our results demonstrate that MtCML40 is involved in the regulation of salt tolerance by targeting MtHKT-dependent Na+ accumulation in M. truncoula

Sevoflurane induces cognitive impairment in young mice via autophagy.

BackgroundAnesthesia may induce neurotoxicity and neurocognitive impairment in young mice. However, the underlying mechanism remains largely to be determined. Meanwhile, autophagy is involved in brain development and contributes to neurodegenerative diseases. We, therefore, set out to determine the effects of sevoflurane on autophagy in the hippocampus of young mice and on cognitive function in the mice.MethodsSix day-old mice received 3% sevoflurane, for two hours daily, on postnatal days (P) 6, 7 and 8. We then decapitated the mice and harvested the hippocampus of the young mice at P8. The level of LC3, the ratio of LC3-II to LC3-I, and SQSTM1/p62 level associated with the autophagy in the hippocampus of the mice were assessed by using Western blotting. We used different groups of mice for behavioral testing via the Morris Water Maze from P31 to P37.ResultsThe anesthetic sevoflurane increased the level of LC3-II and ratio of LC3-II/LC3-I, decreased the p62 level in the hippocampus of the young mice, and induced cognitive impairment in the mice. 3-Methyladenine, the inhibitor of autophagy, attenuated the activation of autophagy and ameliorated the cognitive impairment induced by sevoflurane in the young mice.ConclusionThese data showed that sevoflurane anesthesia might induce cognitive impairment in the young mice via activation of autophagy in the hippocampus of the young mice. These findings from the proof of concept studies have established a system and suggest the role of autophagy in anesthesia neurotoxicity and cognitive impairment in the young mice, pending further investigation

Metabolite profiling for model cultivars of wheat and rice under ozone pollution

As essential source for human consumption, plants of wheat and rice are highly sensitive to ozone (O-3), resulting in significant agricultural losses under O-3 pollution. According to our results, photosynthesis and shoot biomass of wheat and rice were significantly reduced under elevated O-3. The activities of SOD, POD and CAT were responsive to O-3 pollution in two crops. However, lithe is known about the effects of elevated O-3 concentration on their metabolite profiling. The response of metabolites to elevated ozone was investigated in model cultivars of wheat and rice. A total of 172 compounds significantly changed in seedlings of wheat (103) and rice (89) under O-3 pollution. The strong up-regulation of phospholipids and markedly declined of fatty acids were detected in wheat and rice under elevated O-3. Methylerythritol 4-phosphate pathway was altered in both crops with reduced accumulation of carbon compound terpene under O-3 stress. Meanwhile, O-3 treatment led to the high levels of aspartate-derived asparagine or aspartate, which regulated carbon and nitrogen metabolism. Additionally, O-3 suppressed the generation of environmental stress-related flavonoids and cinnamic acids via shikimate pathway in the two crops. Moreover, the biosynthesis of sterols was suppressed and isocitrate was not changed under ozone fumigation in wheat, while both of them were increased in rice. The metabolic results reveal the involvement of O-3-related metabolites in photosynthesis, oxidative stress and carbon/nitrogen balance. Our findings provide valuable information for understanding of ozone's effects on the physiology and metabolite profiling of crop plants, boosting efforts to screen genetic resources for valuable traits to adapt to O-3 pollution