As an important industrial chemical, isoprene is mainly used as a precursor for synthetic rubbers. In addition, it also has wide applications in the field of pharmaceutical and chemical intermediates, food, adhesives and aviation fuel. Compared with conventional petrochemical routes, production of isoprene in microbial systems has been the research focus considering environment friendly and sustainable development features. This article summarizes the metabolic pathways and key enzymes of isoprene biosynthesis, reviews current methods and strategies in improving isoprene production of Escherichia coli, and also gives some basic ideas and expectation.
Butadienes ; Escherichia coli ; Hemiterpenes ; biosynthesis ; Industrial Microbiology ; Metabolic Engineering ; Metabolic Networks and Pathways ; Pentanes

OBJECTIVETo discuss the urine biomarkers in 1,3-butadiene exposed workers, and to provide basement for establishing biological limit value.

METHODS44 BD exposed workers as exposure group and 25 BD non-exposed people as control group including 12 workers in boiler workshop in the same factory and 13 people in one public institute, we collected their in-end-of shift urine, then detected urine BD-derived mercapturic metabolites [3,4-dihydroxybutyl mercapturic acid (DHBMA),1- and 2-monohydroxy-3-butenyl mercapturic acid (MHBMA)] concentrations using UPLC-MS/MS method. Meanwhile, we detected air BD concentration with GC-FID in the workplace, and compared their relationship.

RESULTSlgDHBMA and lg (MHBMA + DHBMA) levels in exposed group (lgDHBMA: 2.51 ± 0.44) µg/L, lg [MHBMA + DHBMA: (2.68 ± 0.27) µg/L] were higher than which in control group (lgDHBMA: (2.20 ± 0.25) µg/L, lg(MHBMA + DHBMA: (2.49 ± 0.34) µg/L), and the differences were significant (P < 0.01). Urine DHBMA was obviously influenced by air BD concentrations (r = 0.539, P = 0.001). The equation of Multiple Regression Analysis was y = 2.417 + 0.520x (x represents air BD dose, and represents urinary DHBMA level). Adjusted R(2) of this model was 0.262. Urinary MHBMA was not affected by smoking, alcohol and years of works.

CONCLUSIONUrine metabolite DHBMA in BD-exposed workers might be major biological exposure indice.

Adult ; Biomarkers ; urine ; Butadienes ; Female ; Humans ; Male ; Middle Aged ; Occupational Exposure ; adverse effects ; Surveys and Questionnaires

Linalool is an important monoterpene, and widely used in food, pharmaceutical and cosmetic industry. The low concentration in plants and the difficulties in extraction restrict its large scale production. Saccharomyces cerevisiae can provide the monoterpene precursor, geranyl diphosphate (GPP) through its endogenous isoprenoid pathway. Therefore, it could be used as the host for monoterpene production. However, the weak metabolic flux through the isoprenoid pathway leads to the insufficient supply of GPP, and results in low monoterpene productivity. In order to increase the metabolic flux, we constructed the integrated expression plasmid pRS305-tHMG1 and free expression plasmid pYLIS-IDI1 to enhance the expression levels of isopentenyl diphosphate isomerase (IDI1) and a truncated 3-hydroxyl-3-methylglutaryl-CoA reductase gene (tHMG1). The two plasmids were separately transformed into S. cerevisiae CEN.PK2-1C, resulting in strains LS01 and LS02. The plasmid pYLIS-IDI1 was further transformed into strain LS01, resulting in strain LS03. GC-MS analysis showed that the linalool concentration was increased by 1.3 times and reached (127.71 +/- 7.68) microg/L. In conclusion, enhancement of the supply of GPP precursors through the regulation of isoprenoid pathway could increase the linalool production in S. cerevisiae.
Biosynthetic Pathways ; genetics ; Butadienes ; metabolism ; Hemiterpenes ; metabolism ; Monoterpenes ; metabolism ; Pentanes ; metabolism ; Saccharomyces cerevisiae ; genetics ; metabolism

The principal objective of this study was to evaluate the chemopreventive and therapeutic effects of a combination of all-trans-retinoic acid (RA) and knockdown of delta-like 1 homologue (Drosophila) (DLK1) on neuroblastoma, the most common malignant disease in children. As unfavorable neuroblastoma is poorly differentiated, neuroblastoma cell was induced differentiation by RA or DLK1 knockdown. Neuroblastoma cells showed elongated neurite growth, a hallmark of neuronal differentiation at various doses of RA, as well as by DLK1 knockdown. In order to determine whether or not a combination of RA and DLK1 knockdown exerts a greater chemotherapeutic effect on neuroblastoma, cells were incubated at 10 nM RA after being transfected with SiRNA-DLK1. Neuronal differentiation was increased more by a combination of RA and DLK1 knockdown than by single treatment. Additionally, in order to assess the signal pathway of neuroblastoma differentiation induced by RA and DLK1 knockdown, treatment with the specific MEK/ERK inhibitors, U0126 and PD 98059, was applied to differentiated neuroblastoma cells. Differentiation induced by RA and DLK1 knockdown increased ERK phosphorylation. The MEK/ERK inhibitor U0126 completely inhibited neuronal differentiation induced by both RA and DLK1 knockdown, whereas PD98059 partially blocked neuronal differentiation. After the withdrawal of inhibitors, cellular differentiation was fully recovered. This study is, to the best of our knowledge, the first to demonstrate that the specific inhibitors of the MEK/ERK pathway, U0126 and PD98059, exert differential effects on the ERK phosphorylation induced by RA or DLK1 knockdown. Based on the observations of this study, it can be concluded that a combination of RA and DLK1 knockdown increases neuronal differentiation for the control of the malignant growth of human neuroblastomas, and also that both MEK1 and MEK2 are required for the differentiation induced by RA and DLK1 knockdown.
Butadienes ; Child ; Flavonoids ; Humans ; Neurites ; Neuroblastoma ; Neurons ; Nitriles ; Phosphorylation ; Signal Transduction ; Tretinoin

Air ; analysis ; Alkenes ; analysis ; Butadienes ; analysis ; Chromatography, Gas ; methods ; Environmental Monitoring ; methods ; Workplace

Isoprene is an important precursor of synthetic rubber material. In our previous study, metabolic engineered Escherichia coli strain (BW-01) was constructed and used to produce isoprene. Based on the theory of protein budget, using synthetic biology strategies including the increased copy number of genes and rare codons, we regulated the expression of key enzyme to improve isoprene production in Escherichia coli strain. Under shake-flask conditions, isoprene productivity of the engineered strain (BW-07) increased by 73% compared with BW-01, reached 761.1 mg/L. It provides a reference for further studies.
Butadienes ; Escherichia coli ; genetics ; metabolism ; Gene Dosage ; Hemiterpenes ; biosynthesis ; Industrial Microbiology ; Metabolic Engineering ; Mevalonic Acid ; Pentanes ; Synthetic Biology

This article reviews newly available knowledge regarding occupational cancer based on an assessment of International Agency for Research on Cancer (IARC) Monograph program from 2006 to 2010. The IARC reviewed the agents to evaluate the carcinogenicity in humans according to their priority. During the last five years, the IARC has reviewed many kinds of agents, including all of the Group 1 carcinogenic agents. Agents belonging to groups other than Group 1 were also reviewed. A few agents, such as shiftwork and firefighting, were reviewed for the first time after introducing the IARC Monograph Program. Most of the reassessed Group 1 agents were reaffirmed, showing that there was sufficient evidence to prove their carcinogenicity to human beings. However, some carcinogens were correlated to the new cancer site, since it was deemed that sufficient evidence was present. For example, larynx and ovary cancer deemed to have sufficient evidence of carciongenicity relating to asbestos exposure, joining lung cancer and mesothelioma. Some agents, such as benzo(a)pyrene, ortho-toluidine, 1,3-butadiene, and others belonging to Group 2A were upgraded to Group 1 based on newly identified epidemiologic findings, along with sufficient animal and mechanistic evidence. Benzo(a)pyrene and benzidine-based dyes were classified as human carcinogens based on sufficient animal and pervasive mechanistic evidence. This new data shows that not only chemical agents but also working conditions, such as stress and shiftwork were found to apply to human carcinogenicity. The IARC listed these agents in order to prioritize their review regarding their carcinogenicity to humans. There is a great need to study these newly emerging agents suspected to relate human carcinogenicity, and deem they are worthy of notice.
Animals ; Asbestos ; Benzo(a)pyrene ; Butadienes ; Carcinogens ; Coloring Agents ; Firefighters ; Humans ; International Agencies ; Larynx ; Lung Neoplasms ; Mesothelioma ; Ovarian Neoplasms ; Polymethacrylic Acids ; Toluidines

OBJECTIVE: Triptolide (TP) has been reported to suppress the expression of mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1), of which main function is to inactivate the extracellular signal-regulated kinase-1/2 (ERK-1/2), the p38 MAPK and the c-Jun N-terminal kinase-1/2 (JNK-1/2), and to exert antiproliferative and pro-apoptotic activities. However, the mechanisms underlying antiproliferative and pro-apoptotic activities of TP are not fully understood. The purpose of this study was to examine whether the down-regulation of MKP-1 expression by TP would account for antiproliferative activity of TP in immortalized HT22 hippocampal cells. METHODS: MKP-1 expression and MAPK phosphorylation were analyzed by Western blot. Cell proliferation was assessed by 3H-thymidine incorporation. Small interfering RNA (siRNA) against MKP-1, vanadate (a phosphatase inhibitor), U0126 (a specific inhibitor for ERK-1/2), SB203580 (a specific inhibitor for p38 MAPK), and SP600125 (a specific inhibitor for JNK-1/2) were employed to evaluate a possible mechanism of antiproliferative action of TP. RESULTS: At its non-cytotoxic dose, TP suppressed MKP-1 expression, reduced cell growth, and induced persistent ERK-1/2 activation. Similar growth inhibition and ERK-1/2 activation were observed when MKP-1 expression was blocked by MKP-1 siRNA and its activity was inhibited by vanadate. The antiproliferative effects of TP, MKP-1 siRNA, and vanadate were significantly abolished by U0126, but not by SB203580 or SP600125. CONCLUSION: Our findings suggest that TP inhibits the growth of immortalized HT22 hippocampal cells via persistent ERK-1/2 activation by suppressing MKP-1 expression. Additionally, this study provides evidence supporting that MKP-1 may play an important role in regulation of neuronal cell growth.
Anthracenes ; Blotting, Western ; Butadienes ; Cell Proliferation ; Diterpenes ; Down-Regulation ; Epoxy Compounds ; Imidazoles ; Neurons ; Nitriles ; p38 Mitogen-Activated Protein Kinases ; Phenanthrenes ; Phosphorylation ; Protein Kinases ; Pyridines ; RNA, Small Interfering ; Vanadates

OBJECTIVETo explore the effects of valsartan and MEK1/2 inhibitor U0126 on atrial fibrosis and connexin40 (Cx40) remodeling in rats treated with isoproterenol (ISO).

METHODS32 male SD rats were randomly divided into control group (A), ISO (5 mg · kg(-1) · d(-1) for 7 days) + DMSO group (B), ISO + U0126 (0.5 mg · kg(-1) · d(-1) for 28 days) group (C, U0126 was dissolved in DMSO), ISO + valsartan (30 mg · kg(-1) · d(-1) for 28 days) + DMSO group (D). Rats were sacrificed after 28 days. The AngIIcontent in myocardial tissue was measured by radioimmunoassay, P-MEK1/2, P-ERK1/2 and Cx40 was detected by immunohistochemistry, atrial fibrosis was determined on HE and Masson stained heart sections.

RESULTSThe content of AngII was significantly higher in group B, C and D compared with group A [(368.243 ± 6.283) ng/L, (357.175 ± 5.944) ng/L, (359.908 ± 2.496) ng/L vs (250.380 ± 4.261) ng/L, P < 0.01]; the degree of atrial fibrosis was significantly lower in group C and D compared with group B [CVF(10.260 ± 0.525)%, (10.238 ± 0.524)% vs (78.710 ± 1.587)%, P < 0.01] while there was no atrial fibrosis in group A [CVF(9.025 ± 0.456)%]; the expression of P-MEK1/2 and P-ERK1/2 was significantly upregulated in group B compared with group A (P-MEK1/2: 0.311 ± 0.007 vs 0.203 ± 0.009, P < 0.01; P-ERK1/2: 0.259 ± 0.003 vs 0.173 ± 0.006, P < 0.01) and significantly lower in group C and D compared with group B (P-MEK1/2: 0.212 ± 0.004, 0.213 ± 0.005 vs 0.311 ± 0.007, P < 0.01, P-ERK1/2: 0.178 ± 0.004, 0.175 ± 0.007 vs 0.259 ± 0.003, P < 0.01). The content of Cx40 was obviously reduced and the distribution of Cx40 was disordered in group B compared with A (0.199 ± 0.007 vs 0.241 ± 0.004, P < 0.01) which could be partly reversed in group C and D (0.239 ± 0.037, 0.235 ± 0.006 vs 0.199 ± 0.007, P < 0.01). All parameters in group C and D were similar (P > 0.05).

CONCLUSIONThe chronically elevated AngII content in myocardium may be related to atrial fibrosis and Cx40 remodeling in this model, valsartan and U0126 were equivalent on attenuating atrial fibrosis and Cx40 remodeling by inhibiting ERK pathways at different levels.

Animals ; Butadienes ; pharmacology ; Connexins ; metabolism ; Fibrosis ; Heart Atria ; metabolism ; pathology ; Male ; Myocardium ; metabolism ; pathology ; Nitriles ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Tetrazoles ; pharmacology ; Valine ; analogs & derivatives ; pharmacology ; Valsartan

Adult ; Butadienes ; adverse effects ; Chemical Industry ; Environmental Monitoring ; Humans ; Middle Aged ; Occupational Exposure ; adverse effects ; Occupational Health ; Physical Examination ; Young Adult