Metabolic network of ammonium in cereal vinegar solid-state fermentation and its response to acid stress.

Shanxi aged vinegar (SAV), a Chinese traditional vinegar, is produced by various microorganisms. Ammonium is an important nitrogen source for microorganisms and a key intermediate for the utilization of non-ammonium nitrogen sources. In this work, an ammonium metabolic network during SAV fermentation was constructed through the meta-transcriptomic analysis of in situ samples, and the potential mechanism of acid affecting ammonium metabolism was revealed. The results showed that ammonium was enriched as the acidity increased. Meta-transcriptomic analysis showed that the conversion of glutamine to ammonia is the key pathway of ammonium metabolism in vinegar and that Lactobacillus and Acetobacter are the dominant genera. The construction and analysis of the metabolic network showed that amino acid metabolism, nucleic acid metabolism, pentose phosphate pathway and energy metabolism were enhanced to resist acid damage to the intracellular environment and cell structures. The enhancement of nitrogen assimilation provides nitrogen for metabolic pathways that resist acid cytotoxicity. In addition, the concentration gradient allows ammonium to diffuse outside the cell, which causes ammonium to accumulate during fermentation.

Design and implementation of a parallel geographically weighted k-nearest neighbor classifier.

The development of high-performance classifiers represents an important step in improving the timeliness of remote sensing classification in the era of high spatial resolution. Geographically weighted k-nearest neighbors (gwk-NN)-a classifier that incorporates spatial information into the traditional k-NN classifier-has demonstrated to be better at mitigating salt-and-pepper noise and misclassification. However, the integration of spatial dependence relationships into spectral information is computationally intensive. To improve computing performance, this paper discusses two commonly used parallel strategies-data and task parallelism-used to parallelize the gwk-NN classifier in the model training and classification stages, and implements the parallel algorithm by calling MPI and GDAL in the C++ development environment on a standalone eight-core computer. We further investigate the potential performance of dual parallelism (the simultaneous exploitation of data and task parallelism) in image classification. The experimental results demonstrate that the parallel gwk-NN classifier can improve the efficiency of high-resolution, remotely sensed images with multiple land cover types. Specifically, data parallelism is more effective than task parallelism in both model training and classification stages because of the minor role of parallel overhead in total execution time. In addition, dual parallelism can take advantage of data and task parallel strategies in the image classification stage, as evidenced by the two largest speedups attained under dual parallelism I (5.28×) and II (5.73×). Comparatively, dual parallelism II, in which priority is given to data decomposition, achieves the best performance by overlapping computation and data transmission, which is compatible with the current trend toward multicore architectures.

Protective Effects of 18ß-Glycyrrhetinic Acid on Neonatal Rats with Hyperoxia Exposure.

Bronchopulmonary dysplasia (BPD) is a common devastating pulmonary complication in preterm infants. Supplemental oxygen is a lifesaving therapeutic measure used for premature infants with pulmonary insufficiency. However, oxygen toxicity is a significant trigger for BPD. Oxidative stress disrupts lung development, accompanied by increased pro-inflammatory cytokines and chemokines expression and immune cells infiltration in lung tissue. Licorice, a typical traditional herbal medicine, is commonly used in the medicine and food industries. 18ß-Glycyrrhetinic acid (18ß-GA), a primary active ingredient of licorice, has powerful anti-oxidative and anti-inflammatory effects. This study aimed to determine whether 18ß-GA has a protective effect on neonatal rats with hyperoxia exposure. Newborn Sprague-Dawley rats were kept in either 21% (normoxia) or 80% O2 (hyperoxia) continuously from postnatal day (PN) 1 to 14. 18ß-GA was injected intragastrically at 50 or 100 mg/kg body weight once a day from PN 1 to 14. We examined the body weight and alveolar development and measured ROS level and the markers of pulmonary inflammation. Mature-IL-1ß and NF-κB pathway proteins, and the NLRP3 inflammasome, were assessed; concurrently, caspase-1 activity was measured. Our results indicated that hyperoxia resulted in alveolar simplification and decreased bodyweight of neonatal rats. Hyperoxia increased ROS level and pulmonary inflammation and activated NF-κB and the NLRP3 inflammasome. 18ß-GA treatment inhibited the activation of NF-κB and the NLRP3 inflammasome, decreased ROS level and pulmonary inflammation, improved alveolar development, and increased the bodyweight of neonatal rats with hyperoxia exposure. Our study demonstrates that 18ß-GA has a protective effect on neonatal rats with hyperoxia exposure.

The Specific Connexin 43-Inhibiting Peptide Gap26 Improved Alveolar Development of Neonatal Rats With Hyperoxia Exposure.

Bronchopulmonary dysplasia (BPD) is a common devastating pulmonary complication in preterm infants. Alveolar maldevelopment is the crucial pathological change of BPD highly associated with oxidative stress-mediated excessive apoptosis. Cellular injury can be propagated and amplified by gap junction (GJ)-mediated intercellular communication. Connexin 43 (Cx43) is the most ubiquitous and critical GJ protein. Gap26 is a specific Cx43 mimic peptide, playing as a Cx43-GJ inhibitor. We hypothesized that Cx43-GJ was involved in alveolar maldevelopment of BPD via amplifying oxidative stress signaling and inducing excessive apoptosis. Neonatal Sprague Dawley rats were kept in either normoxia (21% O2) or hyperoxia (85% O2) continuously from postnatal day (PN) 1 to 14 in the presence or absence of Gap26. Moreover, RLE-6TN cells (type II alveolar epithelial cells of rats) were cultured in vitro under normoxia (21% O2) or hyperoxia (85% O2). RLE-6TN cells were treated by N-acetyl cysteine (NAC) (a kind of reactive oxygen species (ROS) scavenger) or Gap26. Morphological properties of lung tissue are detected. Markers associated with Cx43 expression, ROS production, the activity of the ASK1-JNK/p38 signaling pathway, and apoptotic level are detected in vivo and in vitro, respectively. In vitro, the ability of GJ-mediated intercellular communication was examined by dye-coupling assay. In vitro, our results demonstrated ROS increased Cx43 expression and GJ-mediated intercellular communication and Gap26 treatment decreased ROS production, inhibited ASK1-JNK/p38 signaling, and decreased apoptosis. In vivo, we found that hyperoxia exposure resulted in increased ROS production and Cx43 expression, activated ASK1-JNK/p38 signaling, and induced excessive apoptosis. However, Gap26 treatment reversed these changes, thus improving alveolar development in neonatal rats with hyperoxia exposure. In summary, oxidative stress increased Cx43 expression and Cx43-GJ-mediated intercellular communication. And Cx43-GJ-mediated intercellular communication amplified oxidative stress signaling, inducing excessive apoptosis via the ASK1-JNK/p38 signaling pathway. The specific connexin 43-inhibiting peptide Gap26 was a novel therapeutic strategy to improve the alveolar development of BPD.

Effects of Hyperoxia on Mitochondrial Homeostasis: Are Mitochondria the Hub for Bronchopulmonary Dysplasia?

Mitochondria are involved in energy metabolism and redox reactions in the cell. Emerging data indicate that mitochondria play an essential role in physiological and pathological processes of neonatal lung development. Mitochondrial damage due to exposure to high concentrations of oxygen is an indeed important factor for simplification of lung structure and development of bronchopulmonary dysplasia (BPD), as reported in humans and rodent models. Here, we comprehensively review research that have determined the effects of oxygen environment on alveolar development and morphology, summarize changes in mitochondria under high oxygen concentrations, and discuss several mitochondrial mechanisms that may affect cell plasticity and their effects on BPD. Thus, the pathophysiological effects of mitochondria may provide insights into targeted mitochondrial and BPD therapy.