34 research outputs found
Complete PHB mobilization in Escherichia coli enhances the stress tolerance: a potential biotechnological application
<p>Abstract</p> <p>Background</p> <p>Poly-<it>β</it>-hydroxybutyrate (PHB) mobilization in bacteria has been proposed as a mechanism that can benefit their host for survival under stress conditions. Here we reported for the first time that a stress-induced system enabled <it>E. coli</it>, a non-PHB producer, to mobilize PHB <it>in vivo </it>by mimicking natural PHB accumulation bacteria.</p> <p>Results</p> <p>The successful expression of PHB biosynthesis and PHB depolymerase genes in <it>E. coli </it>was confirmed by PHB production and 3-hydroxybutyrate secretion. Starvation experiment demonstrated that the complete PHB mobilization system in <it>E. coli </it>served as an intracellular energy and carbon storage system, which increased the survival rate of the host when carbon resources were limited. Stress tolerance experiment indicated that <it>E. coli </it>strains with PHB production and mobilization system exhibited an enhanced stress resistance capability.</p> <p>Conclusion</p> <p>This engineered <it>E. coli </it>with PHB mobilization has a potential biotechnological application as immobilized cell factories for biocatalysis and biotransformation.</p
Case report: A novel case of COVID-19 triggered tumefactive demyelinating lesions in one multiple sclerosis patient
The epidemic of COVID-19 is mainly manifested by respiratory symptoms caused by SARS-CoV-2 infection. Recently, reports of central nervous system diseases caused or aggravated by SARS-CoV-2 infection are also increasing. Thus, the COVID-19 pandemic poses an unprecedented challenge to the diagnosis and management of neurological disorders, especially to those diseases which have overlapping clinical and radiologic features with each other. In this study, a 31-year-old female patient had been diagnosed with relapsing–remitting multiple sclerosis (RRMS) initially and subsequently developed tumefactive demyelinating lesions (TDLs) following an infection with SARS-CoV-2. After immunotherapy (glucocorticoid pulses), a significant improvement was observed in her both clinical and radiological characteristics. The patient was started on disease-modifying therapy (DMT) with teriflunomide after cessation of oral glucocorticoids. Following two months of DMT treatment, the imaging follow-up revealed that the patient’s condition continued to deteriorate. This case was characterized by the transformation of a multiple sclerosis patient (MS) infected with SARS-CoV-2 into TDLs and the ineffectiveness of DMT treatment, which added complexity to its diagnosis and treatment. The case also gave us a hint that SARS-CoV-2 has a potential contributory role in inducing or exacerbating demyelinating diseases of the central nervous system that warrants further investigation
Identification and validation of genes with expression patterns inverse to multiple metastasis suppressor genes in breast cancer cell lines
Metastasis suppressor genes (MSGs) have contributed to an understanding of regulatory pathways unique to the lethal metastatic process. When re-expressed in experimental models, MSGs block cancer spread to, and colonization of distant sites without affecting primary tumor formation. Genes have been identified with expression patterns inverse to a single MSG, and found to encode functional, druggable signaling pathways. We now hypothesize that common signaling pathways mediate the effects of multiple MSGs. By gene expression profiling of human MCF7 breast carcinoma cells expressing a scrambled siRNA, or siRNAs to each of 19 validated MSGs (NME1, BRMS1, CD82, CDH1, CDH2, CDH11, CASP8, MAP2K4, MAP2K6, MAP2K7, MAPK14, GSN, ARHGDIB, AKAP12, DRG1, CD44, PEBP1, RRM1, KISS1), we identified genes whose expression was significantly opposite to at least five MSGs. Five genes were selected for further analysis: PDE5A, UGT1A, IL11RA, DNM3 and OAS1. After stable downregulation of each candidate gene in the aggressive human breast cancer cell line MDA-MB-231T, in vitro motility was significantly inhibited. Two stable clones downregulating PDE5A (phosphodiesterase 5A), an enzyme involved in the regulation of cGMP-specific signaling, exhibited no difference in cell proliferation, but reduced motility by 47 and 66 % compared to the empty vector-expressing cells (p = 0.01 and p = 0.005). In an experimental metastasis assay, two shPDE5A-MDA-MB-231T clones produced 47-62 % fewer lung metastases than shRNA-scramble expressing cells (p = 0.045 and p = 0.009 respectively). This study demonstrates that previously unrecognized genes are inversely related to the expression of multiple MSGs, contribute to aspects of metastasis, and may stand as novel therapeutic targets
DNA Double-Strand Break Repair Genes and Oxidative Damage in Brain Metastasis of Breast Cancer
Background
Breast cancer frequently metastasizes to the brain, colonizing a neuro-inflammatory microenvironment. The molecular pathways facilitating this colonization remain poorly understood.
Methods
Expression profiling of 23 matched sets of human resected brain metastases and primary breast tumors by two-sided paired t test was performed to identify brain metastasis–specific genes. The implicated DNA repair genes BARD1 and RAD51 were modulated in human (MDA-MB-231-BR) and murine (4T1-BR) brain-tropic breast cancer cell lines by lentiviral transduction of cDNA or short hairpin RNA (shRNA) coding sequences. Their functional contribution to brain metastasis development was evaluated in mouse xenograft models (n = 10 mice per group).
Results
Human brain metastases overexpressed BARD1 and RAD51 compared with either matched primary tumors (1.74-fold, P < .001; 1.46-fold, P < .001, respectively) or unlinked systemic metastases (1.49-fold, P = .01; 1.44-fold, P = .008, respectively). Overexpression of either gene in MDA-MB-231-BR cells increased brain metastases by threefold to fourfold after intracardiac injections, but not lung metastases upon tail-vein injections. In 4T1-BR cells, shRNA-mediated RAD51 knockdown reduced brain metastases by 2.5-fold without affecting lung metastasis development. In vitro, BARD1- and RAD51-overexpressing cells showed reduced genomic instability but only exhibited growth and colonization phenotypes upon DNA damage induction. Reactive oxygen species were present in tumor cells and elevated in the metastatic neuro-inflammatory microenvironment and could provide an endogenous source of genotoxic stress. Tempol, a brain-permeable oxygen radical scavenger suppressed brain metastasis promotion induced by BARD1 and RAD51 overexpression.
Conclusions
BARD1 and RAD51 are frequently overexpressed in brain metastases from breast cancer and may constitute a mechanism to overcome reactive oxygen species–mediated genotoxic stress in the metastatic brain
Benefit analysis of organic Rankine cycle power generation by using waste heat recovery in Refinery
Under the goal of achieving “carbon neutrality”, increasing energy-saving and reducing emissions has become a long-term strategy to ensure the sustainable development of China’s social economy. The unrecycled waste heat leads to a high energy penalty in refinery. This paper presents an Organic Rankine Cycle (ORC) power generation technology, which through the thermodynamic cycle to recover the waste heat from the Aromatics Complex units. This process is simulated and analysed from the environmental point. The results indicate that the application of ORC in aromatics combined units can indirectly save 41040 tons of coal every year. The annual emission of CO2 is reduced by 94455 tons. The proposed ORC system provides technological route for refineries to achieve waste heat recovery, thus advancing the green transition of the petrochemical plants
Genome-Wide Identification and Characterization of Growth Regulatory Factor Family Genes in Medicago
Growth Regulatory Factors (GRF) are plant-specific transcription factors that play critical roles in plant growth and development as well as plant tolerance against stress. In this study, a total of 16 GRF genes were identified from the genomes of Medicago truncatula and Medicago sativa. Multiple sequence alignment analysis showed that all these members contain conserved QLQ and WRC domains. Phylogenetic analysis suggested that these GRF proteins could be classified into five clusters. The GRF genes showed similar exon–intron organizations and similar architectures in their conserved motifs. Many stress-related cis-acting elements were found in their promoter region, and most of them were related to drought and defense response. In addition, analyses on microarray and transcriptome data indicated that these GRF genes exhibited distinct expression patterns in various tissues or in response to drought and salt treatments. In particular, qPCR results showed that the expression levels of gene pairs MtGRF2–MsGRF2 and MtGRF6–MsGRF6 were significantly increased under NaCl and mannitol treatments, indicating that they are most likely involved in salt and drought stress tolerance. Collectively, our study is valuable for further investigation on the function of GRF genes in Medicago and for the exploration of GRF genes in the molecular breeding of highly resistant M. sativa
Achieving mainstream nitrogen removal through coupling anammox with denitratation
Achieving maintream anammox is critical for energy-neutral sewage treatment. This study presents a new way to achieve mainstream anammox, which couples anammox with denitratation (nitrate reduction to nitrite) instead of nitritation (ammonium oxidation to nitrite). An anoxic/oxic (A/O) biofilm system treating systhetic domestic wastewater was used to demonstrate this concept for over 400 days. This A/O biofilm system achieved a total nitrogen (TN) removal efficiency of 80 ± 4% from the influent with a low C/N ratio of 2.6 and a TN concentration of 60.5 mg/L. Nitrogen removal via anammox was found to account for 70% of dinitrogen production in the anoxic reactor. Batch tests confirmed that the anoxic biofilm could oxidize ammonium using nitrite as electron acceptor, and that it had a higher nitrate reduction rate than the nitrite reduction rate, thus producing nitrite for the anammox reaction. Metagenomic analysis showed that Candidatus Jettenia caeni and Candidatus Kuenenia stuttgartiensis were the top two dominant species in anoxic biofilm. Genes involved in the metabolism of the anammox process were detected in anoxic biofilm. The abundance of nitrate reductase (73360 hits) was much higher than nitrite reductase (13114 hits) in anoxic biofilm. This system can be easily integrated with the high-rate activated sludge technology, which produces an effluent with a low C/N ratio. While this new design consumes 21% more oxygen in comparison to the currently studied nitritation/anammox process, the nitrite-producing process appears to be more stable
Identification and Characterization of Abiotic Stress–Responsive NF-YB Family Genes in Medicago
Nuclear factor YB (NF-YB) are plant-specific transcription factors that play a critical regulatory role in plant growth and development as well as in plant resistance against various stresses. In this study, a total of 49 NF-YB genes were identified from the genomes of Medicago truncatula and Medicago sativa. Multiple sequence alignment analysis showed that all of these NF-YB members contain DNA binding domain, NF-YA interaction domain and NF-YC interaction domain. Phylogenetic analysis suggested that these NF-YB proteins could be classified into five distinct clusters. We also analyzed the exon–intron organizations and conserved motifs of these NF-YB genes and their deduced proteins. We also found many stress-related cis-acting elements in their promoter region. In addition, analyses on genechip for M. truncatula and transcriptome data for M. sativa indicated that these NF-YB genes exhibited a distinct expression pattern in various tissues; many of these could be induced by drought and/or salt treatments. In particular, RT-qPCR analysis revealed that the expression levels of gene pairs MsNF-YB27/MtNF-YB15 and MsNF-YB28/MtNF-YB16 were significantly up-regulated under NaCl and mannitol treatments, indicating that they are most likely involved in salt and drought stress response. Taken together, our study on NF-YB family genes in Medicago is valuable for their functional characterization, as well as for the application of NF-YB genes in genetic breeding for high-yield and high-resistance alfalfa
Identification and Characterization of Abiotic Stress Responsive CBL-CIPK Family Genes in Medicago
The calcineurin B-like protein (CBL) and CBL-interacting protein kinase (CIPK) play important roles in plant signal transduction and response to abiotic stress. Plants of Medicago genus contain many important forages, and their growth is often affected by a variety of abiotic stresses. However, studies on the CBL and CIPK family member and their function are rare in Medicago. In this study, a total of 23 CBL and 58 CIPK genes were identified from the genome of Medicago sativa as an important forage crop, and Medicaog truncatula as the model plant. Phylogenetic analysis suggested that these CBL and CIPK genes could be classified into five and seven groups, respectively. Moreover, these genes/proteins showed diverse exon-intron organizations, architectures of conserved protein motifs. Many stress-related cis-acting elements were found in their promoter region. In addition, transcriptional analyses showed that these CBL and CIPK genes exhibited distinct expression patterns in various tissues, and in response to drought, salt, and abscisic acid treatments. In particular, the expression levels of MtCIPK2 (MsCIPK3), MtCIPK17 (MsCIPK11), and MtCIPK18 (MsCIPK12) were significantly increased under PEG, NaCl, and ABA treatments. Collectively, our study suggested that CBL and CIPK genes play crucial roles in response to various abiotic stresses in Medicago