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Biomedical subjects

Ling Chen

Publications and source records attributed to Ling Chen.

At least 37 records · Page 2Linked to original sources

Non-covalent interaction of 2', 4', 5', 7'-tetrabromo-4, 5, 6, 7-tetrachlorofluorescein with proteins and its application.

The interactions of 2', 4', 5', 7'-tetrabromo-4, 5, 6, 7-tetrachlorofluorescein (TBTCF) with BSA, ovalbumin (OVA) and poly-L-lysine (PLYS) at pH 3.70 have been investigated by combination of the spectral correction technique and the Langmuir isothermal adsorption. The active connection actions such as ion pairs, van der Waals' force, hydrogen bond, hydrophobic bond were proposed to explain the non-covalent interaction between TBTCF and BSA, OVA and PLYS. Effects of the electrolyte and high temperature indicated that union of the active connections between TBTCF and BSA and OVA was too firm to be destroyed. The relationship between the binding number of TBTCF and variety fraction of the amino acid residues was analyzed. The binding number of TBTCF depended on the number of positively charged amino acid residues. The other amino acid residues surrounded and seized TBTCF by hydrogen bonds and hydrophobic bonds when the electrostatic attraction pulled TBTCF to link protein. In addition, a novel method named the absorbance ratio difference was established for determination of protein in trace level and was applied with much higher sensitivity than the ordinary method.

Animals↗

Altered keratin 17 peptide ligands inhibit in vitro proliferation of keratinocytes and T cells isolated from patients with psoriasis.

BACKGROUND: Identification of critical autoantigenic T-cell epitopes is key to developing antigen-based therapies for autoimmune diseases, including psoriasis. Our previous work demonstrated that 3 peptides on keratin 17 are able to stimulate peripheral blood lymphocytes of HLA-DRB1*07-positive patients with psoriasis and to serve as immunodominant T-cell epitopes. OBJECTIVE: We sought to determine antagonistic altered peptide ligands to psoriatic T cells with a down-modulatory effect in inhibiting keratinocyte proliferation. METHODS: Psoriatic altered peptide ligands were generated by single alanine residue substitutions at a critical T-cell receptor contact residue position. Antagonistic altered peptide ligands were identified by suppression screening of psoriatic T-cell activation and keratinocyte proliferation. RESULTS: Altered peptide ligands 119R and 355L can inhibit psoriatic T-cell activation more effectively than other altered peptide ligands, especially 355L, with inhibition of T-cell proliferation and the secretion of interferon gamma and interleukin 2 in parallel with the up-regulation of interleukins 4 and 10 as well as transforming growth factor-beta. In coincubation assay, altered peptide ligands 119R and 355L can down-regulate the function of psoriatic T cells more effectively than wild-type epitopes solely, but less effectively than altered peptide ligands solely. In prepulse assay altered peptide ligand 119R can down-regulate the activation of psoriatic T cells more effectively than in coincubation but less effectively as compared with altered peptide ligand 119R only. Altered peptide ligand 355L was also shown to have a similar presentation. T-cell culture supernatants (1:100) from the concentrations (10 microg.mL(-1) and 100 microg.mL(-1) with 119R, 100 microg.mL(-1) with 355L) were more effective than the other ratios in inhibiting keratinocyte proliferation. LIMITATIONS: This study had a relatively small sample size (52 patients and 48 healthy controls). CONCLUSION: Our findings show that the altered peptide ligands 119R (VAALEEANTELEVKI) and 355L (ENRYCVQASQIQGLI) are capable of inhibiting proliferative responses of psoriatic T cells and keratinocyte proliferation in vitro, at least, with enhanced helper T cell type 2 polarization. Thus, to our knowledge, this article is the first report of the demonstration of therapeutic activity of altered peptide ligands derived from keratin 17.

Cell Proliferation↗

Glia maturation factor gamma (GMFG): a cytokine-responsive protein during hematopoietic lineage development and its functional genomics analysis.

Human hematopoiesis was evaluated using the techniques of controlled stem cell differentiation, two-dimensional gel electrophoresis-based proteomics, and functional genomics. We provide the first report that glia maturation factor gamma (GMFG) is a cytokine-responsive protein in erythropoietin-induced and granulocyte-colony stimulating factor-induced hematopoietic lineage development. Results from global functional genomics analysis indicate that GMFG possesses several other features: hematopoietic tissue-specific gene expression, a promoter concentrated with high-score hematopoiesis-specific transcription factors, and possible molecular coevolution with a rudimentary blood/immune system. On the basis of our findings, we hypothesize that GMFG is a hematopoietic-specific protein that may mediate the pluripotentiality and lineage commitment of human hematopoietic stem cells.

Amino Acid Sequence↗

[Expression and secretion of human bone morphogenetic protein-7 in Pichia pastoris].

The synonymous codons are used in a highly non-random manner in hosts of widely divergent species, which is termed "codon usage bias". Several reports suggest that codon usage bias sometimes frustrate attempts to express high levels of exogenous genes. In this study, we attempted to express mature peptide of human bone morphogenetic protein-7(hBMP7), with optimized codons in P. pastoris expression system. Three low-usage ARG codons (CGG or CGA) of gene fragment coding the mature peptide of hBMP7 have been successfully converted into P. pastoris-preferred ARG codons (AGA) by overlap extension PCR-based multiple-site-directed mutagenesis for a high level expression of hBMP7 mature peptide. The present results showed that the production level (25.45 mg/L) of codon-optimized hbmp7 had a remarkably improvement of 4.6-fold relative to that (5.5 mg/L) of non-codon-optimized hbmp7. Furthermore, a strain haboring multi-copy of codon-optimized hbmp7 expression cassette was screened, and showed a increased level of expression with 2-fold more potent than the single-copy one. The recombinant hBMP7 mature peptide were produced as a 18 kD monomer proteins, and were easily purified from culture supernatants by using ion-exchange chromatography. Functional assay demonstrated that rhBMP7 could induce ectopic cartilage formation, although its inductive ability was much less active than CHO cell-derived hBMP7.

Animals↗

Photomutagenicity of anhydroretinol and 5,6-epoxyretinyl palmitate in mouse lymphoma cells.

Retinyl palmitate (RP) is frequently used as an ingredient in cosmetics and other retail products. We previously reported that, under UVA light irradiation, RP is facilely decomposed into multiple products, including anhydroretinol (AR) and 5,6-epoxyretinyl palmitate (5,6-epoxy-RP). We also determined that combined treatment of mouse lymphoma cells with RP and UVA irradiation produced a photomutagenic effect. In this study, we evaluated the photomutagenicity of AR and 5,6-epoxy-RP, in L5178Y/Tk+/- mouse lymphoma cells. Treatment of cells with AR or 5,6-epoxy-RP alone at 10 and 25 microg/mL for 4 h did not show a positive mutagenic response. However, because these doses did not induce the required amount of cytotoxicity for mouse lymphoma assay, we are unable to determine whether or not these two compounds are mutagenic. Treatment of cells with 1-25 microg/mL AR or 5,6-epoxy-RP under UVA light (315-400 nm) for 30 min (1.38 mW/cm2) produced a synergistic photomutagenic effect. At 10 microg/mL (37.3 microM) AR with UVA exposure, the mutant frequency (MF) was about 3-fold higher than that for UVA exposure alone, whereas the MF for 25microg/mL (46.3microM) of 5,6-epoxy-RP + UVA was approximately 2-fold higher than that for UVA exposure alone. Compared with previous results for RP + UVA treatment, the potency of the induced phototoxicity and photomutagenicity was AR > RP > 5,6-epoxy-RP. To elucidate the underlying photomutagenic mechanism, we examined the loss of heterozygosity (LOH) at four microsatellite loci spanning the entire chromosome 11 for mutants induced by AR or 5,6-epoxy-RP. Most mutants lost the Tk+ allele, and more than 70% of the chromosome damage extended to 38 cM in chromosome length. AR + UVA induced about twice as many mutants that lost all four microsatellite markers from the chromosome 11 carrying the Tk+ allele as RP + UVA or 5,6-epoxy-RP + UVA. These results suggest that two of RP's photodecomposition products are photomutagenic in mouse lymphoma cells, causing events that affect a large segment of the chromosome.

Animals↗

Identification of key genes responsible for cytokine-induced erythroid and myeloid differentiation and switching of hematopoietic stem cells by RAGE.

We utilized a unique culture system to analyze the expression patterns of gene, protein, and cell surface antigen, and the biological process of the related genes in erythroid and myeloid differentiation and switching of hematopoietic stem cells (HSCs) in response to cytokine alterations. Gene-specific fragments (266) identified from five populations of cytokine-stimulated HSCs were categorized into three groups: (1) expressed specifically in a single cell population; (2) expressed in two cell populations, and (3) expressed in three or more populations. Of 145 defined cDNAs, three (2%) were novel genes. Protein two-dimensional gel electrophoresis and flow cytometry analyses showed overlapped and distinguished protein expression profiles in the cell populations studied. Biological process mapping of mRNAs expressed in erythroid and myeloid lineages indicated that mRNAs shared by both lineages attended 'core processes,' whereas genes specifically expressed in either lineage alone were related to specific processes or cellular maturation. Data from this study support the hypothesis that committed HSCs (E14 or G14) cells can still be redirected to develop into myeloid or erythroid cells when erythropoietin (EPO) is replaced with granulocyte-colony stimulating factor (G-CSF) under erythroid-cultured condition or G-CSF with EPO in myeloid-cultured environment, respectively. Our results suggest that genes or proteins co-expressed in erythroid and myeloid lineages may be essential for the lineage maintenance and switching in hematopoiesis.

Cell Differentiation↗

Efficient AAV1-AAV2 hybrid vector for gene therapy of hemophilia.

Adeno-associated virus (AAV) serotype 1 (AAV1) has been shown to be more effective than the well-studied AAV serotype 2 (AAV2) in muscle gene transfer. Replacement of amino acids 350 to 430 of AAV2 VP1 with the corresponding amino acids from VP1 of AAV1 resulted in a hybrid vector, termed AAV-221-IV, which behaved similarly to AAV1 in vitro and in vivo in muscle. Intramuscular injection of 1x10(11) vector particles per mouse of hybrid vector carrying a human FIX transgene in CD4 knockout mice resulted in an average level of human FIX in the plasma of 450 ng/ml, 4- to 10-fold higher than in mice injected with an AAV2 vector carrying the same transgene, and 80% of the transgene levels in animals treated with the same dose of AAV1. DNA analysis of injected muscle showed a 10-fold higher copy number after gene delivery by the hybrid vector compared with AAV2. A comparison of total DNA versus DNA from intact virus particles suggests a higher stability of hybrid virus particles. These results suggest that changes in the AAV capsid have an effect on virus-cell receptor interaction, and also influence trafficking and processing of the virus particle in the cell. This "hybrid vector" retains the heparin-binding sites of AAV2 and, therefore, can be purified by passage through a heparin-Sepharose column with the same efficiency as AAV2. When tested in vivo, either in CD4 knockout mice or in a hemophilic mouse model, the heparin-purified hybrid vector showed >10-fold higher activity than similarly purified AAV2. This demonstrates the utility of this hybrid vector in the performance of large-scale heparin column purification to generate a vector with a high expression profile for muscle-directed gene delivery. Initiation of clinical studies with this hybrid vector may be facilitated because it differs from AAV2 by only nine amino acids.

Animals↗

How does salt retention raise blood pressure?

A critical question in hypertension research is: How is long-term blood pressure controlled? Excessive NaCl ingestion or NaCl retention by the kidneys and the consequent tendency toward plasma volume expansion lead to hypertension. Nevertheless, the precise mechanisms linking salt to high blood pressure are unresolved. The discovery of endogenous ouabain, an adrenocortical hormone, provided an important clue. Ouabain, a selective Na+ pump inhibitor, has cardiotonic and vasotonic effects. Plasma endogenous ouabain levels are significantly elevated in approximately 40% of patients with essential hypertension and in animals with several forms of salt-dependent hypertension. Also, prolonged ouabain administration induces hypertension in rodents. Mice with mutant Na+ pumps or Na/Ca exchangers (NCX) and studies with a ouabain antagonist and an NCX blocker are revealing the missing molecular mechanisms. These data demonstrate that alpha2 Na+ pumps and NCX1 participate in long-term regulation of vascular tone and blood pressure. Pharmacological agents or mutations in the alpha2 Na+ pump that interfere with the action of ouabain on the pump, and reduced NCX1 expression or agents that block NCX all impede the development of salt-dependent or ouabain-induced hypertension. Conversely, nanomolar ouabain, reduced alpha2 Na+ pump expression, and smooth muscle-specific overexpression of NCX1 all induce hypertension. Furthermore, ouabain and reduced alpha2 Na+ pump expression increase myogenic tone in isolated mesenteric small arteries in vitro, thereby tying these effects directly to the elevation of blood pressure. Thus, endogenous ouabain, and vascular alpha2 Na+ pumps and NCX1, are critical links between salt and hypertension. New pharmacological agents that act on these molecular links have potential in the clinical management of hypertension.

Animals↗

A new method of noninvasive brain-edema monitoring in stroke: cerebral electrical impedance measurement.

OBJECTIVE: To explore the primary regularity of cerebral electrical impedance (CEI) change in healthy people, patients with intracerebral hemorrhage (ICH) and patients with cerebral infarction (CI). METHODS: CEI of 200 healthy volunteers, 78 patients with ICH and 51 patients with CI were measured by noninvasive brain-edema monitor. The results of perturbative index (PI) converted from CEI were compared with the volumes of infarction, hematoma and surrounding edema, which were calculated by image analysing system according to MRI or CT scan. RESULTS: (1) In the normal groups, PI in the left and right sides of cerebral hemispheres was respectively 7.98 +/- 0.95 and 8.02 +/- 0.71, and there was no significant difference between the two sides (p>0.05). (2) In the patients with ICH, PI of the hematoma side initially was lower than the other side, but then increased and finally exceeded that of the other side. The average transitional time was 19.67 +/- 11.52 hours. Perturbative index of the hematoma side after the transitional time was much higher than before the transitional time in the same patients (7.79 +/- 0.75 versus 7.09 +/- 0.72) (p<0.001). The volumes of peri-hematoma edema were also significantly larger after the transitional time than before (24.32 +/- 12.86 versus 13.33 +/- 6.12) (p<0.05). There was a positive correlation between the PI of hematoma side and the volumes of peri-hematoma edema (p<0.01). (3) In the patients with arterothrombotic cerebral infarction, PI in the infarct side was higher than that in the opposite side 3-5 days after onset (8.93 +/- 1.89 versus 8.58 +/- 1.61) (p<0.001), and PI of the infarct side had a positive correlation with the volume of infarction (p<0.001). (4) The sensitivity of PI was high when the volumes of lesions were >20 ml or the position of them were located in the basal ganglia, but was low when the volumes were <20 ml or the position near the midline. CONCLUSION: CEI may be a useful parameter for noninvasively monitoring the change of brain edema and hematoma in stroke at bedside. It could be a good complement to CT and MRI.

Adult↗

Invasive micropapillary carcinoma of the breast: association of pathologic features with lymph node metastasis.

Invasive micropapillary carcinoma (IMPC) of the breast is characterized by a high incidence of axillary lymph node metastasis. To investigate the relationship between pathologic features and lymph node metastasis, 51 cases of breast carcinoma with IMPC components were studied. Immunohistochemical analysis for vascular endothelial growth factor (VEGF)-C and VEGF receptor (VEGFR)-3 was performed, and lymphatic vessel density was measured. The main findings included a significantly increased number of positive lymph nodes and/or an increased rate of lymph node metastasis in IMPC with a higher histologic grade, prominent stromal infiltration of lymphocytes, and higher VEGF-C expression and lymphatic vessel density. The percentage of IMPC component in the tumor was not associated with the incidence of lymph node metastasis. The results suggest that the histologic grade, lymphatic vessel density, and lymphocyte infiltration of IMPC are the key factors that influence lymph node metastasis. Further studies are required to elucidate the mechanisms underlying the lymphotropism of this distinct variant of breast carcinoma.

Breast Neoplasms↗

[Relationship between lymph node metastasis and pathologic features of invasive micropapillary carcinoma of breast].

OBJECTIVE: To investigate the relationship between lymph node metastasis and pathologic features of invasive micropapillary carcinoma (IMPC) of the breast. METHODS: Histopathologic features and status of lymph node metastasis of fifty-one cases of IMPC were studied by microscopic examination, immunohistochemical staining (VEGF-C and VEGFR-3) and analysis of lymphatic vessel density. RESULTS: (1) The number of positive lymph nodes in histologic grade II/III IMPCs was significantly higher (mean 12.5) than that in histologic grade I tumors (mean 4.0). (2) The incidence of nodal metastases in IMPCs with lymphocyte infiltration (+)/(++) was significantly higher (27/28, 96.4%) than that in tumors with no or minimal lymphocyte infiltration (-)/(+/-) (14/23, 60.9%), and the number of positive nodes was also higher (mean 14.4) in tumors with lymphocyte infiltration compared with those without (mean 4.6). (3) In IMPCs with histologic grade II/III, the expression of VEGF-C was significantly higher than that of histologic grade I tumors (P = 0.03). VEGF-C expression was in positive correlation with lymph node metastasis (P = 0.006) and lymphatic vessel density (P = 0.009). Lymph node metastasis was also correlated with lymphatic vessel density (P = 0.007). (4) The percentage of IMPC component in the tumor did not correlate with nodal metastasis. The metastatic foci in lymph node were all IMPC or mainly IMPC. (5) Fourteen of twenty-eight cases (14/28, 50%) of IMPC containing ductal carcinoma in-situ (DCIS) were DCIS of micropapillary type. CONCLUSIONS: The histologic grade, lymphatic vessel density and lymphocyte infiltration are key histological features that are correlated with lymph node metastasis of IMPC. The expression of VEGF-C and VEGFR-3 may play an important role in the development of lymph node metastasis of IMPC. Micropapillary type DCIS may be the early stage of IMPC.

Adult↗

[Efficacy of FAEV regimen in treatment of high-risk drug-resistant gestational trophoblastic tumor].

OBJECTIVE: To evaluate the efficacy of floxuridine, actinomycin D, etoposide, vincristine (FAEV) regimen in treatment of high-risk drug-resistant gestational trophoblastic tumor (GTT). METHODS: From October 2001 to May 2004, 11 cases of high-risk drug-resistant GTT were treated with FAEV regimen. The International Federation of Gynecology and Obstetrics (FIGO) prognosis score (2000) was 7 to 13 (median 9). All patients were referred to Peking Union Medical College Hospital because of failure of chemotherapy previously. After the FAEV treatment, they were followed up for 15 to 42 months. RESULTS: Seven cases (64%, 7/11) were cured by FAEV regimen. The median treatment course for serum human chorionic gonadotropin reaching normal level was 3. Four cases (36%, 4/11) showed drug-resistant to FAEV regimen. The major side effect of FAEV regimen was myelosuppression. Granulocyte colony stimulating factor support was needed after 98% (63/64) of the courses. CONCLUSION: For those high-risk drug-resistant GTT cases, FAEV regimen could be considered as an effective choice of treatment.

Adult↗

[Determination of triazines in surface water using solid phase extraction-high performance liquid chromatography].

A method was developed to monitor triazines in surface water using the combination of solid phase extraction (SPE) and high performance liquid chromatography. Four different SPE cartridges were tested for extracting six triazines, including atrazine (A), simazine (S), prometryn (P), desethylatrazine (DEA), 2-hydroxyatrazine (OHA) and desisopropylatrazine (DIA), and finally ENVI-18 was selected as optimal. The method for solid phase extraction was further systematically studied for details. Optimal results of orthogonal design were determined as follows: pH 6, 5 mL methanol as eluting solvent, and no methanol added into water sample before extraction. The detection limits of six triazines were 0.14 microg/L for P, 0.12 microg/L for A, 0.08 microg/L for S, 0.08 microg/L for DEA, 0.10 microg/L for OHA and 0.18 microg/L for DIA. This method was applied for environmental aquatic samples, and the results showed that the concentration of prometryn in a lake was detected as (9.33 +/- 0.27) microg/L, as well as the concentrations of atrazine and prometryn in a river were detected as (5.28 +/- 0.43) microg/L and (7.12 +/- 0.54) microg/L respectively.

English Abstract↗

[Comparison of color character of VITA shade guide and the custom shade guide].

OBJECTIVE: To compare the color character of VITA shade guide and the custom shade guide with metal substrate. METHODS: Color of 9 sites of 5 series of VITA shade guides and custom shade guides with metal substrate were measured by means of PR-650 spectrophotometer. RESULTS: The color range of VITA shade guide were that L* was 56.86-73.86, a* was-1.29-3.69, b* was 7.09-21.94, and the transparence was 3.20-7.59. The color range of the custom shade guide was that L* was 60.59-78.54, a* was -1.09-4.99, b* was 7.60-22.35, and the transparence was 0.23-10.98. L*, a* and b* of the custom shade guide with metal substrate were higher than VITA shade guide, and the transparence was differet. The color difference of homonymy shade tab between custom shade guide and VITA shade guide was larger than 1.5 NBS. CONCLUSION: There is color difference between VITA shade guide and custom shade guide. Metal substrate has effects on the color of cero-metal prosthesis, and color selection in clinic should be carefully considered.

Color↗

[Effects of CaCOC addition under Zn supply on wheat seedlings growth and Zn uptake].

High concentration calcium carbonate in calcareous soils usually limits plant Zn uptake. In this paper, a solution culture experiment was conducted to study the effects of CaCO3 addition with or no Zn supply on the growth and Zn uptake of three genotypes winter wheat seedlings. The results showed that Zn supply or CaCO3 addition had no significant effects on seedlings biomass and root/canopy ratio, and there was no significant difference among the three genotypes. CaCO3 addition led to leaf chlorosis. No matter with or no Zn supply, CaCO3 addition had no significant effects on the Zn concentration and accumulation in wheat root, stem, and leaf. Zn supply increased the Zn concentration in Yuanfeng 998, Zhongyu 6, and Xiaoyan 22 by 80.0%, 104.8% and 139.6%, respectively. For Yuanfeng 998, a sensitive genotype to Zn-deficiency, the increment of Zn concentration and accumulation was much lower than that of Zhongyu 6 and Xiaoyan 22, non-sensitive genotypes to Zn-deficiency. Zn supply or CaCO3 addition had no significant effects on the P content in root, stem, and leaf, but the corresponding P content of Yuanfeng 998 was obviously lower than that of the other two genotypes. Zn supply greatly decreased the P/Zn ratio in root, stem and leaf, and CaCO3 addition also showed the same tendency. Under Zn-deficiency, CaCO3 addition caused leaf chlorosis, but did not decrease wheat plant Zn uptake. In conclusion, at least under solution culture condition, high concentration calcium carbonate had no obvious inhibitory effect on plant zinc uptake, and whether this situation was true in calcareous soils is worthy to be further investigated.

Biomass↗

[An experimental study on rat bone marrow mesenchymal stem cells transfected with dentin sialophosphoprotein gene in vitro].

OBJECTIVE: To evaluate the expression of dentin sialophosphoprotein (DSPP) in transfected rat bone marrow mesenchymal stem cells (BM-MSC) and the influence of the transfection. METHODS: Plasmid containing mice dentin DSPP was constructed by using the cytomegalovirus (CMV) promoter and then transfected the cultured BM-MSC by lipofectamine; The expression of Pax-9 and dentin matrix protein 1 (DMP1) gene of transfected BM-MSC were detected by RT-PCR. The expression of DSPP was examined by immunocytochemical staining, and the formation ratio of mineralized nodules of transfected BM-MSC was compared with untransfected ones after mineralized induction. RESULTS: The constructed pcDNA3.1(+)/mDSPP could produced 3.0 kb and 5.4 kb fragments, DSPP gene and Pax9 gene were expressed 24 h and 48 h respectively, after BM-MSC were transfected Pax-9 gene was exprssed, but DMP1 gene was not; Immunohistochemical staining showed that DSPP was positive in transfected BM-MSC; The formation ratio of mineralized nodules of transfected BM-MSC was higher than that of untransfected ones after mineralized induction. CONCLUSIONS: The expression of mice DSPP in BM-MSC by gene transfection can induce the expression of tooth development-associated gene Pax9 and enhance the formation of mineralized nodules, which suggests that DSPP gene might induce odontogenic differentiation of BM-MSC.

Animals↗

[Biodegradability and degradation mechanism of 3-fluorophenol by the activated sludge].

An acclimated activated sludge was examined for its ability to degrade 3-fluorophenol in aerobic batch cultures. The result indicated that the organism degrades up to 100 mg/L 3-fluorophenol completely with approximately 100% fluoride anion release within 16 h. 3-Fluorophenol can serve as the sole carbon source and energy source for the organism. The acclimated activated sludge can degrade 3-fluorophenol effectively. The degradation mechanism study reveal that the initial step in the aerobic biodegradation of 3-fluorophenol is its transformation to fluorocatechol. Following transformation of the fluorophenol to fluorocatechol, ring cleavage by catechol 1, 2-dioxygenase proceedes via an ortho-cleavage pathway, then defluorination occurres.

Acclimatization↗