Mortality and complications in elderly patients with cervical spine injuries.

PURPOSE: To assess the complications and mortality in elderly individuals with cervical spine injuries. METHODS: This retrospective observational study was conducted in a tertiary care hospital in a rural area in Japan. Data sets from the trauma registry (January 2011 to March 2018) were analyzed. Patients with cervical spine injury were divided into those aged ≥ 65 years (group Y) and > 65 years (group E). We then analyzed age, sex, 30-day mortality, hospital stay, level of cervical spine injury, presence of cervical vertebral fracture, perioperative complications (pneumonia, urinary tract infection, and severe bedsore), neurological deficit (Frankel classification), Abbreviated Injury Scale (AIS) score, and Injury Severity Score (ISS). RESULTS: We evaluated a total of 398 patients; among them, 177 were included in group Y and 221 in group E. The assessed parameters were as follows: age (group Y/E; 48.7/75.9 years), men (78.0/72.3%), 30-day mortality (8.5/10.0%, p = 0.159), hospital stay (17.2/19.1 days, p = 0.36), level of cervical spine injury (C1 [5.7/4.5%], C2 [12.4/15.8%], C3 [10.2/17.2%], C4 [14.1/16.3%], C5 [26.6/22.2%], C6 [22.0/12.2%], and C7 [11.3/10.9%]), vertebral fracture (56.6/61.9%), central cord syndrome (36.2/33%), operation (18.6/13.1%), pneumonia (6.8/11.8%, p = 0.077), urinary tract infection (4.0/6.3%, p = 0.26), severe bedsore (0/1.8%, p = 0.068), Frankel classification (grade A [5.7/6.3%], grade B [6.8/7.7%], grade C [24.9/28.5%], grade D [17.5/11.8%], and grade E [34.5/33.9%]), mean AIS score in the cervical spine (3.3/3.5, p = 0.04), and mean ISS (23.2/22.2, p = 0.38). C3 injuries tended to be higher in group E. CONCLUSION: Mortality and morbidity associated with cervical spine injuries did not differ between younger and older patients. Nevertheless, vigilance is required for the detection of C3 injury in elderly individuals.

Can postoperative deltoid weakness after cervical laminoplasty be prevented by using intraoperative neurophysiological monitoring?

Laminoplasty, frequently performed in patients with cervical myelopathy, is safe and provides relatively good results. However, motor palsy of the upper extremities, which occurs after decompression surgery for cervical myelopathy, often reduces muscle strength of the deltoid muscle, mainly in the C5 myotome. The aim of this study was to investigate prospectively whether postoperative deltoid weakness (DW) can be predicted by performing intraoperative neurophysiological monitoring (IONM) during cervical laminoplasty and to clarify whether it is possible to prevent palsy using IONM. We evaluated the 278 consecutive patients (175 males and 103 females) who underwent French-door cervical laminoplasty for cervical myelopathy under IONM between November 2008 and December 2016 at our hospital. IONM was performed using muscle evoked potential after electrical stimulation to the brain [Br(E)-MsEP] from the deltoid muscle. Seven patients (2.5%) developed DW after surgery (2 with acute and 5 with delayed onset). In all patients, deltoid muscle strength recovered to ≥ 4 on manual muscle testing 3-6 months after surgery. Persistent IONM alerts occurred in 2 patients with acute-onset DW. To predict the acute onset of DW, Br(E)-MsEP alerts in the deltoid muscle had both a sensitivity and specificity of 100%. The PPV of persistent Br(E)-MsEP alerts had both a sensitivity and specificity of 100% for acute-onset DW. There was no change in Br(E)-MsEP in patients with delayed-onset palsy. The incidence of deltoid palsy was relatively low. Persistent Br(E)-MsEP alerts of the deltoid muscle had a 100% sensitivity and specificity for predicting a postoperative acute deficit. IONM was unable to predict delayed-onset DW. In only 1 patient were we able to prevent postoperative DW by performing a foraminotomy.

Association of Lumbar Spondylolisthesis With Low Back Pain and Symptomatic Lumbar Spinal Stenosis in a Population-based Cohort: The Wakayama Spine Study.

STUDY DESIGN: Cross-sectional study. OBJECTIVE: To determine the association between lumbar spondylolisthesis and low back pain and symptomatic lumbar spinal stenosis (LSS) in a population-based cohort. SUMMARY OF BACKGROUND DATA: The basic epidemiology of lumbar spondylolisthesis is not well known. There is little information regarding the association between lumbar spondylolisthesis and clinical symptoms such as low back pain and LSS symptoms. METHODS: This cross-sectional study included data from 938 participants (308 males, 630 females; mean age, 67.3 years; range, 40-93 years). Lumbar spondylolisthesis was defined as a slip of ≥5%. Diagnostic criteria for symptomatic LSS required the presence of both leg symptoms and radiographic LSS findings on magnetic resonance imaging. The prevalence of low back pain and symptomatic LSS was compared between those with or without spondylolisthesis. Furthermore, we determined the association between the amount of slippage and presence of symptomatic LSS. RESULTS: The prevalence of spondylolisthesis at any level was 15.8% in the total sample, 13.0% in males, and 17.1% in females; the prevalence was not significantly different between males and females (P = 0.09). In both, males and females, symptomatic LSS was related to spondylolisthesis [odds ratio (OR): 2.07; 95% CI: 1.20-3.44]; however, no such association was found for spondylolisthesis and presence of low back pain. The amount of slippage was not related to the presence of symptomatic LSS (P = 0.93). CONCLUSION: This population-based cohort study revealed that lumbar spondylolisthesis had a closer association with leg symptoms than with low back pain. There was a significant difference in the presence of symptomatic LSS between participants with and without spondylolisthesis. However, the amount of slippage was not related to the presence of symptomatic LSS. LEVEL OF EVIDENCE: 3.

A Mathematical Model of the Olfactory Bulb for the Selective Adaptation Mechanism in the Rodent Olfactory System.

To predict the odor quality of an odorant mixture, the interaction between odorants must be taken into account. Previously, an experiment in which mice discriminated between odorant mixtures identified a selective adaptation mechanism in the olfactory system. This paper proposes an olfactory model for odorant mixtures that can account for selective adaptation in terms of neural activity. The proposed model uses the spatial activity pattern of the mitral layer obtained from model simulations to predict the perceptual similarity between odors. Measured glomerular activity patterns are used as input to the model. The neural interaction between mitral cells and granular cells is then simulated, and a dissimilarity index between odors is defined using the activity patterns of the mitral layer. An odor set composed of three odorants is used to test the ability of the model. Simulations are performed based on the odor discrimination experiment on mice. As a result, we observe that part of the neural activity in the glomerular layer is enhanced in the mitral layer, whereas another part is suppressed. We find that the dissimilarity index strongly correlates with the odor discrimination rate of mice: r = 0.88 (p = 0.019). We conclude that our model has the ability to predict the perceptual similarity of odorant mixtures. In addition, the model also accounts for selective adaptation via the odor discrimination rate, and the enhancement and inhibition in the mitral layer may be related to this selective adaptation.

Development of a support tool for the clinical diagnosis of symptomatic lumbar intra- and/or extra-foraminal stenosis.

BACKGROUND: Not all lumbar intra- and/or extra-foraminal stenosis (LIEFS) on MRI is symptomatic. Therefore, the establishment of clinical diagnostic tools that can identify patients with symptomatic LIEFS is crucial in the clinical setting. The aim of this study was to develop a support tool for clinical diagnosis of LIEFS. METHODS: Patients with L5 radiculopathy alone were prospectively enrolled. Fifty-one patients with lumbar spinal canal stenosis only at the L4-5 level and 49 patients with LIEFS only at the L5-S1 level were extracted from this cohort. We compared the two groups with regard to 12 variables--three subjective and three objective items from the Japanese Orthopaedic Association (JOA) score; Kemp's sign; results of the lumbar flexion test, Bonnet test, and Freiberg test; pain on sitting; and pain when recumbent--to determine which factors were associated with a high index of clinical suspicion of LIEFS. RESULTS: The significant predictors of a final diagnosis of LIEFS were identified as follows: pain when recumbent, Freiberg and Bonnet test results, and pain on sitting. To develop a diagnostic tool, a scoring system (0-20 points) was formulated on the basis of the contribution ratios of these risk factors. To determine the contribution ratio, an integer score was assigned to the identified risk factors as follows: pain when recumbent = 9 points, Freiberg = 5 points, Bonnet = 3 points, and pain on sitting = 3 points. The Hosmer-Lemeshow statistic for this scoring system was p = 0.063, and confirmed that it was a good model. Receiver operating characteristic (ROC) curve analysis demonstrated a cut-off value of 5 points, an area under the ROC curve of 0.87435, sensitivity of 75.5 %, and specificity of 82.3 %. CONCLUSIONS: We believe that the use of this tool in the clinical setting will improve the accuracy of diagnosing symptomatic LIEFS, which will lead to improved quality of patient care.

The prevalence of cervical myelopathy among subjects with narrow cervical spinal canal in a population-based magnetic resonance imaging study: the Wakayama Spine Study.

BACKGROUND CONTEXT: A narrow cervical spinal canal (CSC) is a well-known risk factor for cervical myelopathy (CM). However, no epidemiologic data of the CSC based on a population-based cohort are available. PURPOSE: The purpose of the study was to investigate the age-related differences in CSC diameters on plain radiographs and to examine the associated magnetic resonance imaging (MRI) abnormalities including cervical cord compression and increased signal intensity (ISI) as well as the clinical CM with the narrow CSC. STUDY DESIGN/SETTING: This was a cross-sectional study. PARTICIPANT SAMPLE: Data were obtained from the baseline survey of the Wakayama Spine Study that was performed from 2008 to 2010 in a western part of Japan. Finally, a total of 959 subjects (319 men and 640 women; mean age, 66.4 years) were included. OUTCOME MEASURES: The outcome measures included in the study were the CSC diameter at C5 level on plain radiographs, cervical cord compression and ISI on sagittal T2-weighted MRI, and physical signs related to CM (eg, the Hoffmann reflex, hyperreflexia of the patellar tendon, the Babinski reflex, sensory and motor function, and bowel/bladder symptoms). METHODS: The age-related differences of CSC diameters in men and women were investigated by descriptive statistics. The prevalence of MRI abnormalities and clinical CM was compared among the groups divided by the CSC diameter (less than 13, 13-15, and 15 mm or more). In addition, a logistic regression analysis was performed to determine the association of the CSC diameter with cervical cord compression/clinical CM after overall adjustment for age, sex, and body mass index. RESULTS: The CSC diameter was narrower with increasing age in both men and women. The prevalence of cervical cord compression, ISI, and the clinical CM was significantly higher in the narrower CSC group. The prevalence of cervical cord compression, ISI, and CM among subjects with CSC diameter less than 13 mm was 38.0%, 5.4%, and 10.1%, respectively. In the logistic model, the CSC diameter was a significant predictive factor for the clinical CM (p<.0001). CONCLUSIONS: This study firstly confirmed the age-related differences in CSC diameters and the significant association of the narrow CSC diameter with CM in a population-based cohort.

A comparison between the human sense of smell and neural activity in the olfactory bulb of rats.

Generally, odor qualities are evaluated via sensory tests in which predefined criteria are assessed by panelists and stochastically analyzed to reduce human inconsistencies. Because this method requires multiple, well-trained human subjects, a more convenient approach is required to enable predictions of odor qualities. In this article, we propose an approach involving linking internal states of the olfactory system with perceptual characteristics. In the study, the glomerular responses of rats were taken to represent internal olfactory system states. Similarities between the glomerular responses of rats were quantified by correlations between glomerular activity patterns, overlap rate of strongly activated part across glomerular activity patterns, and the similarity between histograms of the strength of activity. These indices were then compared with perceptual similarities measured from human subjects in sensory tests. The results of experiments involving 22 odorants showed medium strength correlations between each index and perceptual similarity. In addition, when the 3 indices were combined using their Euclidean distance, we observed middle to high correlations (r = 0.65-0.79) to human perceptual similarity. We also report the results of our use of a machine learning technique to classify the odorants into a similar and dissimilar category. Although the correct rate of classification varied from 33.3% to 92.9%, these results support the feasibility of linking the glomerular responses of rats to human perception.

Prevalence of cervical cord compression and its association with physical performance in a population-based cohort in Japan: the Wakayama Spine Study.

STUDY DESIGN: A population-based magnetic resonance imaging (MRI) study of the cervical spine. OBJECTIVE: This study was undertaken in order to investigate the prevalence of cervical cord compression (CCC) and to examine the association between CCC and physical performance measures in a population-based cohort established in Japan. SUMMARY OF BACKGROUND DATA: Population-based cohort studies of the prevalence of CCC, although essential for clarification of the prevalence of slowly progressive disease and specification of the time of incidence of CCC, are not available. METHODS: This cross-sectional study was performed as a part of the Research on Osteoarthritis/osteoporosis Against Disability study, a large-scale population-based cohort study in Japan. From 1011 inhabitants who underwent MRI examinations, images of the cervical spine of 977 subjects (324 men and 653 women, mean age of 66.4 yr) were evaluated. CCC was assessed by sagittal T2-weighted MRI and was defined as spinal cord compression. The prevalence of CCC and its association with myelopathic signs (hyper-reflexia of the patellar tendon and Hoffmann and Babinski reflexes) were examined. In addition, physical performance measures (grip and release test, grip strength, 6-m walking time, step length, chair-stand time, and one-leg standing time) were tested. RESULTS: The prevalence of CCC was 24.4% and was significantly higher in men (29.3% in men and 21.9% in women, P = 0.011). The prevalence of CCC was higher with increasing age in both sexes. CCC was not significantly associated with any myelopathic signs but was significantly associated with grip and release test, 6-m walking time, step length, and chair-stand time. CONCLUSION: In this MRI study, the prevalence of CCC was examined. The present results indicate that CCC correlates with physical performance measures from an early stage of the disease before myelopathic signs appear.

Distinct degree of radiculopathy at different levels of peripheral nerve injury.

BACKGROUND: Lumbar radiculopathy is a common clinical problem, characterized by dorsal root ganglion (DRG) injury and neural hyperactivity causing intense pain. However, the mechanisms involved in DRG injury have not been fully elucidated. Furthermore, little is known about the degree of radiculopathy at the various levels of nerve injury. The purpose of this study is to compare the degree of radiculopathy injury at the DRG and radiculopathy injury proximal or distal to the DRG. RESULTS: The lumbar radiculopathy rat model was created by ligating the L5 nerve root 2 mm proximal to the DRG or 2 mm distal to the DRG with 6.0 silk. We examined the degree of the radiculopathy using different points of mechanical sensitivity, immunohistochemistry and in vivo patch-clamp recordings, 7 days after surgery. The rats injured distal to the DRG were more sensitive than those rats injured proximal to the DRG in the behavioral study. The number of activated microglia in laminas I-II of the L5 segmental level was significantly increased in rats injured distal to the DRG when compared with rats injured proximal to the DRG. The amplitudes and frequencies of EPSC in the rats injured distal to the DRG were higher than those injured proximal to the DRG. The results indicated that there is a different degree of radiculopathy at the distal level of nerve injury. CONCLUSIONS: Our study examined the degree of radiculopathy at different levels of nerve injury. Severe radiculopathy occurred in rats injured distal to the DRG when compared with rats injured proximal to the DRG. This finding helps to correctly diagnose a radiculopathy.

An artificial neural network approach for glomerular activity pattern prediction using the graph kernel method and the gaussian mixture functions.

This paper proposes a neural network model for prediction of olfactory glomerular activity aimed at future application to the evaluation of odor qualities. The model's input is the structure of an odorant molecule expressed as a labeled graph, and it employs the graph kernel method to quantify structural similarities between odorants and the function of olfactory receptor neurons. An artificial neural network then converts odorant molecules into glomerular activity expressed in Gaussian mixture functions. The authors also propose a learning algorithm that allows adjustment of the parameters included in the model using a learning data set composed of pairs of odorants and measured glomerular activity patterns. We observed that the defined similarity between odorant structure has correlation of 0.3-0.9 with that of glomerular activity. Glomerular activity prediction simulation showed a certain level of prediction ability where the predicted glomerular activity patterns also correlate the measured ones with middle to high correlation in average for data sets containing 363 odorants.

Biomimetic control based on a model of chemotaxis in Escherichia coli.

In the field of molecular biology, extending now to the more comprehensive area of systems biology, the development of computer models for synthetic cell simulation has accelerated extensively and has begun to be used for various purposes, such as biochemical analysis. These models, describing the highly efficient environmental searching mechanisms and adaptability of living organisms, can be used as machine-control algorithms in the field of systems engineering. To realize this biomimetic intelligent control, we require a stripped-down model that expresses a series of information-processing tasks from stimulation input to movement. Here we selected the bacterium Escherichia coli as a target organism because it has a relatively simple molecular and organizational structure, which can be characterized using biochemical and genetic analyses. We particularly focused on a motility response known as chemotaxis and developed a computer model that includes not only intracellular information processing but also motor control. After confirming the effectiveness and validity of the proposed model by a series of computer simulations, we applied it to a mobile robot control problem. This is probably the first study showing that a bacterial model can be used as an autonomous control algorithm. Our results suggest that many excellent models proposed thus far for biochemical purposes can be applied to problems in other fields.

Pseudomonas aeruginosa as a model microorganism for investigation of chemotactic behaviors in ecosystem.

Motile bacteria sense changes in the concentration of chemicals in environments and respond in a behavioral manner. This behavioral response is called chemotaxis. Bacterial chemotaxis can be viewed as an important prelude to metabolism, prey-predator relationships, symbiosis, infections, and other ecological interactions in biological communities. Genome analysis reveals that a large number of environmental motile bacteria possess a number of genes involved in chemosensing and chemotatic signal transduction. Pseudomonas aeruginosa has a very complex chemosensory system with more than 20 chemotaxis (che) genes in five distinct clusters and 26 chemoreceptor (methyl-accepting chemotaxis protein [mcp]) genes. Among the 26 MCPs of P. aeruginosa, nine have been identified as MCPs for amino acids, inorganic phosphate, oxygen, ethylene, and volatile chlorinated aliphatic hydrocarbons, whereas 3 MCPs were demonstrated to be involved in biofilm formation and biosynthesis of type IV pilus. Six che genes are essential for chemotactic responses, while genes in Pil-Chp cluster and Wsp cluster are involved in type IV pilus synthesis and twitching motility and biofilm formation, respectively. P. aeruginosa, with its complex chemotaxis system, is a better model microorganism for investigating ecological aspects of chemotaxis in environmental bacteria than Escherichia coli and Salmonella enterica serovar Typhimurium, which possess a relatively simpler chemotaxis system.

Performance of mice in discrimination of liquor odors: behavioral evidence for olfactory attention.

We examined performance of mice in discrimination of liquor odors by Y-maze behavioral assays. Thirsty mice were initially trained to choose the odor of a red wine in the Y-maze. After successful training (>70% concordance for each trained mouse), the individual mice were able to discriminate the learned red wine from other liquors, including white wine, rosé wine, sake, and plum liqueur. However, when the mice were tested to distinguish fine differences between 2 brands of red wine, their performance significantly varied among the individual trained mice. Among 10 mice tested, 2 mice were able to discriminate between the red wines (>75% concordance) whereas 6 mice failed to distinguish between them (50-67% concordance, where chance could be assumed to be 50%). More importantly, 2 other mice exhibited lower than 30% concordance, indicating that they were more attracted to the nonrewarded red wine compared with the learned one. This result suggested that the individual mice directed attention to different subsets of volatile components emanating from the rewarded red wine, when they were trained to choose the liquor odor in the Y-maze. Selective attention of mice was also observed in Y-maze behavioral assays using the mixtures of 3 or less pure odorants. Additionally, we also observed that the olfactory attention of mice could be modified through their learning experiences.

Use of an Escherichia coli recombinant producing thermostable polyphosphate kinase as an ATP regenerator to produce fructose 1,6-diphosphate.

Heat-treated Escherichia coli producing Thermus polyphosphate kinase regenerated ATP by using exogenous polyphosphate. This recombinant could be used as a platform to produce valuable compounds in combination with thermostable phosphorylating or energy-requiring enzymes. In this work, we demonstrated the production of fructose 1,6-diphosphate from fructose and polyphosphate.

Inhibition of quorum sensing in Pseudomonas aeruginosa by N-acyl cyclopentylamides.

N-octanoyl cyclopentylamide (C8-CPA) was found to moderately inhibit quorum sensing in Pseudomonas aeruginosa PAO1. To obtain more powerful inhibitors, a series of structural analogs of C8-CPA were synthesized and examined for their ability to inhibit quorum sensing in P. aeruginosa PAO1. The lasB-lacZ and rhlA-lacZ reporter assays revealed that the chain length and the ring structure were critical for C8-CPA analogs to inhibit quorum sensing. N-decanoyl cyclopentylamide (C10-CPA) was found to be the strongest inhibitor, and its concentrations required for half-maximal inhibition for lasB-lacZ and rhlA-lacZ expression were 80 and 90 microM, respectively. C10-CPA also inhibited production of virulence factors, including elastase, pyocyanin, and rhamnolipid, and biofilm formation without affecting growth of P. aeruginosa PAO1. C10-CPA inhibited induction of both lasI-lacZ by N-(3-oxododecanoyl)-L-homoserine lactone (PAI1) and rhlA-lacZ by N-butanoyl-L-homoserine lactone (PAI2) in the lasI rhlI mutant of P. aeruginosa PAO1, indicating that C10-CPA interferes with the las and rhl quorum-sensing systems via inhibiting interaction between their response regulators (LasR and RhlR) and autoinducers.

Effect of mineral elements on phosphorus release from heated sewage sludge.

The aim of this work was to examine the influence of mineral elements on phosphorus (P) release from heated waste sludges. Energy dispersive X-ray microanalysis suggested that P was associated with Al, Ca, and Mg on the surface of waste sludge biomass obtained from six wastewater treatment plants. The extent of P release decreased with increasing the total concentrations of Al, Mg, and Ca in waste sludges. The addition of Al2(SO4)3, Ca(OH)2, CaCl2, MgSO4, or NaAlO2 to activated sludges, which were taken from a bench-scale EBPR process, reduced the P release significantly.

Identification and characterization of the chemotactic transducer in Pseudomonas aeruginosa PAO1 for positive chemotaxis to trichloroethylene.

Pseudomonas aeruginosa PAO1 is repelled by trichloroethylene (TCE), and the methyl-accepting chemotaxis proteins PctA, PctB, and PctC serve as the major chemoreceptors for negative chemotaxis to TCE. In this study, we found that the pctABC triple mutant of P. aeruginosa PAO1 was attracted by TCE. Chemotaxis assays of a set of mutants containing deletions in 26 potential mcp genes revealed that mcpA (PA0180) is the chemoreceptor for positive chemotaxis to TCE. McpA also detects tetrachloroethylene and dichloroethylene isomers as attractants.

Transcriptional analysis of the multicopy hao gene coding for hydroxylamine oxidoreductase in Nitrosomonas sp. strain ENI-11.

The nitrifying bacterium Nitrosomonas sp. strain ENI-11 has three copies of the gene encoding hydroxylamine oxidoreductase (hao(1), hao(2), and hao(3)) on its genome. Broad-host-range reporter plasmids containing transcriptional fusion genes between hao copies and lacZ were constructed to analyze the expression of each hydroxylamine oxidoreductase gene (hao) copy individually and quantitatively. beta-Galactosidase assays of ENI-11 harboring reporter plasmids revealed that all hao copies were transcribed in the wild-type strain. Promoter analysis of hao copies revealed that transcription of hao(3) was highest among the hao copies. Expression levels of hao(1) and hao(2) were 40% and 62% of that of hao(3) respectively. Transcription of hao(1) was negatively regulated, whereas a portion of hao(3) transcription was read through transcription from the rpsT promoter. When energy-depleted cells were incubated in the growth medium, only hao(3) expression increased. This result suggests that it is hao(3) that is responsible for recovery from energy-depleted conditions in Nitrosomonas sp. strain ENI-11.

Isolation and characterization of benzene-tolerant Rhodococcus opacus strains.

Twenty-two benzene-utilizing bacteria were isolated from soil samples. Among them, three isolates were highly tolerant to benzene. They grew on benzene when liquid benzene was added to the basal salt medium at 10--90% (v/v). Taxonomical analysis identified the benzene-tolerant isolates as Rhodococcus opacus. One of the benzene-tolerant isolates, designated B-4, could utilize many aromatic and aliphatic hydrocarbons including benzene, toluene, styrene, xylene, ethylbenzene, propylbenzene, n-octane and n-decane as sole sources of carbon and energy. Strain B-4 grew well in the presence of 10% (v/v) organic solvents that it was capable of using as growth substrates. Genetic analysis revealed the benzene dioxygenase pathway is involved in benzene catabolism in strain B-4. A deletion-insertion mutant defective in the benzene dioxygenase large and small subunits genes (bnz A 1 and bnz A 2) was as tolerant to organic solvents as the wild-type strain B-4, suggesting that utilization or degradation of organic solvents is not essential for the organic solvent tolerance of R. opacus B-4.

Identification of chemosensory proteins for trichloroethylene in Pseudomonas aeruginosa.

The involvement of the chemotaxis gene cluster 1 (cheYZABW) and cheR in repellent responses of Pseudomonas aeruginosa to trichloroethylene (TCE) is described and three methyl-accepting chemotaxis proteins (MCPs) for TCE are identified. TCE chemotaxis assays of a number of deletion-insertion mutants of P. aeruginosa PAO1 revealed that the chemotaxis gene cluster 1 and cheR are required for negative chemotaxis to TCE. Mutant strains which contained deletions in pctA, pctB and pctC showed decreased responses to TCE. The pctA, pctB and pctC genes have been reported to encode MCPs for amino acids [K. Taguchi et al., Microbiology, 143, 3223--3229 (2000)]. The pctA mutation more severely impaired chemotactic responses to TCE than did those of pctB and pctC, suggesting that PctA is the major MCP for TCE among the three MCPs. The pctA, pctB and pctC mutant strains showed decreased responses to chloroform and methylthiocyanate. This result demonstrates that PctA, PctB and PctC are also involved in repellent responses to chloroform and methylthiocyanate.