Near-real-time Biomonitoring of Heavy Metals Using the Xenoassay® System

Heavy metals have widespread industrial uses and have been found in increasing quantities as contaminants in all components of the biosphere. Water and sediment of rivers near industrial areas such as the Juru River in Penang and Langat River in Selangor are polluted with heavy metals. Thus, rapid and fast methods to detect the presence of heavy metals in the environment are necessary. Existing instrumental methods such as atomic absorption and emission spectrometry are very sensitive but the sole use of these instruments for heavy metal detection is extremely expensive, needs a skillful person to operate and is not amenable to near-real-time analysis. The best scenario for routine biomonitoring of heavy metals is the marriage between instrument- and bioassays. Currently, the USEPA has recognized whole cell-based bioassays such as as PolytoxTM and Microtox® for the detection of heavy metals. Unfortunately these cell-based assays cannot be used as real-time or near real-time assays in the field as they require bulky incubators. Near-real-time monitoring of heavy metals giving results in less than one hour is very useful in environmental CSI (Criminal Scene Investigation) or ECSI where temporal and spatial concentrations of heavy metals in running waters are a challenge to environmentalists to pinpoint heavy metals POS (point of source) for legal purposes. Enzyme-based inhibitive assays are simple, rapid and fast and could be developed for near real-time assays. We have developed an inhibitive assay system –Xenoassay® based on proteases for the assay of heavy metals. The system could detect the heavy metals mercury, cadmium, lead, copper, zinc and silver at the sub parts per million level. Field trial near-real-time assay capability shows promising results

Characterization of a sodium dodecyl sulphate-degrading Pseudomonas sp. strain DRY15 from Antarctic soil

A bacterium capable of biodegrading surfactant sodium dodecyl sulphate (SDS) was isolated from Antarctic soil. The isolate was tentatively identified as Pseudomonas sp. strain DRY15 based on carbon utilization profiles using Biolog GN plates and partial 16S rDNA molecular phylogeny. Growth characteristic studies showed that the bacterium grew optimally at 10 degrees C, 7.25 pH, 1 g l(-1) SDS as a sole carbon source and 2 g l(-1) ammonium sulphate as nitrogen source. Growth was completely inhibited at 5 g l(-1) SDS. At a tolerable initial concentration of 2 g l(-1), approximately 90% of SDS was degraded after an incubation period of eight days. The best growth kinetic model to fit experimental data was the Haldane model of substrate inhibition with a correlation coefficient value of 0.97. The maximum growth rate was 0.372 hr(-1) while the saturation constant or half velocity constant (Ks) and inhibition constant (Ki), were 0.094% and 11.212 % SDS, respectively. Other detergent tested as carbon sources at 1 g l(-1) was Tergitol NP9, Tergitol 15S9, Witconol 2301 (methyl oleate), sodium dodecylbenzene sulfonate (SDBS), benzethonium chloride, and benzalkonium chloride showed Tergitol NP9, Tergitol 15S9, Witconol 2301 and the anionic SDBS supported growth with the highest growth exhibited by SDBS.Fil: Halmi, M. I. E.. University of Putra; MalasiaFil: Hussin, W. S. W.. University of Putra; MalasiaFil: Aqlima, A.. University of Putra; MalasiaFil: Syed, M. A.. University of Putra; MalasiaFil: Ruberto, Lucas Adolfo Mauro. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: MacCormack, Walter P.. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Yukor, M. Y.. University of Putra; Malasi

An inhibitive determination method for heavy metals using tomato crude proteases

A new inhibitive heavy metals determination method using extract from Lycopersicon esculentum or tomato from has been developed. The enzyme was assayed using the casein-Coomassie-dye-binding method. In the absence of inhibitors, casein was hydrolysed to completion and the Coomassie-dye was unable to stain the protein and the solution became brown. In the presence of metals, the hydrolysis of casein was inhibited and the solution remained blue. The inhibitions shown by lead, chromium and zinc were, 67.9, 53.1 and 53 %, respectively. The IC50 (concentration causing 50% inhibition) values were 1.407, 0.835 and 0.707 mg/l, respectively. The limits of quantitation (LOQ), for zinc, chromium and lead were 0.729, 0.506 and 0.541 mg/l, respectively. The limits of detection (LOD) for zinc, chromium and lead were 0.032, 0.0317 and 0.0317 mg/l, respectively. The IC50 value for zinc was much lower than the IC50 values for papain and Rainbow trout assays. The IC50 value for zinc was lower than the immobilized urease assay. Other toxic heavy metals, such as silver, arsenic, copper, mercury and cadmium, did not inhibit the crude proteolytic enzyme activity. Based on the characteristics, crude protease enzyme from L. esculentum (tomato) can be used to detect heavy metals in various samples in conjunction with the dye-binding assay

Alsolation and characterization of a heavy metalreducing enterobacteriaceae bacterium strain DRY 7 with the ability to assimilate phenol and diesel

Background/Objectives: Molybdenum, phenol and diesel are toxic to organism, and are part of global pollution. Their removal using microorganisms with multiple detoxification ability is being intensely sought as a cleaner and economic approach. Methods/Statistical analysis: A soil suspension was spread plated on a minimal salts media supplemented with molybdenum. Blue colonies, indicating molybdenum reduction was then screened for phenol and diesel degradation capabilities. Findings: A molybdenum-reducing bacterium locally isolated showed the ability to grow on phenol and diesel. The bacterium required pHs of between 5.8 and 6.3 and temperatures of between 30 and 40oC for optimal reduction. Among the carbon sources tested for supporting reduction, glucose was the best. A critical concentration of phosphate at just 5 mM was required, while molybdenum (sodium molybdate) was required between 15 and 25 mM. The absorption spectrum of the Mo-blue produced showed a characteristic maximum peak at 865 nm. The reduction of molybdenum was inhibited by the ions mercury, copper, chromium, lead and silver by 78.9, 78.4, 77.4, 53.5 and 36.8%, respectively. Analysis using phylogenetic analysis identifies the bacterium as Enterobacteriaceae bacterium strain DRY7. Growth on phenol and diesel as carbon sources showed that the optimal concentrations supporting growth was between 300 and 400 mg/L and between 300 and 500 mg/L, respectively. Application/Improvements: The capacity of this bacterium to detoxify a number of toxicants is an important property or bioremediation of soils contaminated with multiple toxicants

Kinetics of Molybdenum Reduction to Molybdenum Blue by Bacillus sp. Strain A.rzi

Molybdenum is very toxic to agricultural animals. Mo-reducing bacterium can be used to immobilize soluble molybdenum to insoluble forms, reducing its toxicity in the process. In this work the isolation of a novel molybdate-reducing Gram positive bacterium tentatively identified as Bacillus sp. strain A.rzi from a metal-contaminated soil is reported. The cellular reduction of molybdate to molybdenum blue occurred optimally at 4 mM phosphate, using 1% (w/v) glucose, 50 mM molybdate, between 28 and 30 ∘ C and at pH 7.3. The spectrum of the Mo-blue product showed a maximum peak at 865 nm and a shoulder at 700 nm. Inhibitors of bacterial electron transport system (ETS) such as rotenone, sodium azide, antimycin A, and potassium cyanide could not inhibit the molybdenum-reducing activity. At 0.1 mM, mercury, copper, cadmium, arsenic, lead, chromium, cobalt, and zinc showed strong inhibition on molybdate reduction by crude enzyme. The best model that fitted the experimental data well was Luong followed by Haldane and Monod. The calculated value for Luong's constants max , , , and was 5.88 mole Mo-blue hr −1 , 70.36 mM, 108.22 mM, and 0.74, respectively. The characteristics of this bacterium make it an ideal tool for bioremediation of molybdenum pollution

Eating disorders: from twin studies to candidate genes and beyond

Substantial effort has been put into the exploration of the biological background of eating disorders, through family, twin and molecular genetic studies. Family studies have shown that anorexia (AN) and bulimia nervosa (BN) are strongly familial, and that familial etiologic factors appear to be shared by both disorders. Twin studies often focus on broader phenotypes or subthreshold eating disorders. These studies consistently yielded moderate to substantial heritabilities. In addition, there has been a proliferation of molecular genetic studies that focused on Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 1994) AN and BN. Seven linkage regions have been identified in genome-wide screens. Many genetic association studies have been performed, but no consistent association between a candidate gene and AN or BN has been reported. Larger genetic association studies and collaborations are needed to examine the involvement of several candidate genes and biological pathways in eating disorders. In addition, twin studies should be designed to assist the molecular work by further exploring genetic determinants of endophenotypes, evaluating the magnitude of contribution to liability of measured genotypes as well as environmental risk factors related to eating disorders. In this manner twin and molecular studies can move the field forward in a mutually informative way

Psychological and weight-related characteristics of patients with anorexia nervosa-restricting type who later develop bulimia nervosa

<p>Abstract</p> <p>Background</p> <p>Patients with anorexia nervosa-restricting type (AN-R) sometimes develop accompanying bulimic symptoms or the full syndrome of bulimia nervosa (BN). If clinicians could predict who might change into the bulimic sub-type or BN, preventative steps could be taken. Therefore, we investigated anthropometric and psychological factors possibly associated with such changes.</p> <p>Method</p> <p>All participants were from a study by the Japanese Genetic Research Group for Eating Disorders. Of 80 patients initially diagnosed with AN-R, 22 changed to the AN-Binge Eating/Purging Type (AN-BP) and 14 to BN for some period of time. The remaining 44 patients remained AN-R only from the onset to the investigation period. Variables compared by ANOVA included anthropometric measures, personality traits such as Multiple Perfectionism Scale scores and Temperament and Character Inventory scores, and Beck Depression Inventory-II scores.</p> <p>Results</p> <p>In comparison with AN-R only patients, those who developed BN had significantly higher current BMI (p < 0.05) and maximum BMI in the past (p < 0.05). They also scored significantly higher for the psychological characteristic of parental criticism (p < 0.05) and lower in self-directedness (p < 0.05), which confirms previous reports, but these differences disappeared when the depression score was used as a co-variant. No significant differences were obtained for personality traits or depression among the AN-R only patients irrespective of their duration of illness.</p> <p>Conclusion</p> <p>The present findings suggest a tendency toward obesity among patients who cross over from AN-R to BN. Low self-directedness and high parental criticism may be associated with the development of BN by patients with AN-R, although the differences may also be associated with depression.</p

Dissecting the Shared Genetic Architecture of Suicide Attempt, Psychiatric Disorders, and Known Risk Factors

Background Suicide is a leading cause of death worldwide, and nonfatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both have substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders. Methods We conducted a genome-wide association study (GWAS) of 29,782 suicide attempt (SA) cases and 519,961 controls in the International Suicide Genetics Consortium (ISGC). The GWAS of SA was conditioned on psychiatric disorders using GWAS summary statistics via multitrait-based conditional and joint analysis, to remove genetic effects on SA mediated by psychiatric disorders. We investigated the shared and divergent genetic architectures of SA, psychiatric disorders, and other known risk factors. Results Two loci reached genome-wide significance for SA: the major histocompatibility complex and an intergenic locus on chromosome 7, the latter of which remained associated with SA after conditioning on psychiatric disorders and replicated in an independent cohort from the Million Veteran Program. This locus has been implicated in risk-taking behavior, smoking, and insomnia. SA showed strong genetic correlation with psychiatric disorders, particularly major depression, and also with smoking, pain, risk-taking behavior, sleep disturbances, lower educational attainment, reproductive traits, lower socioeconomic status, and poorer general health. After conditioning on psychiatric disorders, the genetic correlations between SA and psychiatric disorders decreased, whereas those with nonpsychiatric traits remained largely unchanged. Conclusions Our results identify a risk locus that contributes more strongly to SA than other phenotypes and suggest a shared underlying biology between SA and known risk factors that is not mediated by psychiatric disorders.publishedVersio

Is season of birth related to disordered eating and personality in women with eating disorders?

We assessed the relation between season of birth and eating disorder symptoms and personality characteristics in a sample of 880 women with eating disorders and 580 controls from two Price Foundation Studies. Eating disorder symptoms were assessed using Structured Interview of Anorexic and Bulimic Disorders and the Structured Clinical Interview for DSM-IV. Personality traits were assessed using the Temperament and Character Inventory and the Frost Multidimensional Perfectionism Scale. Date of birth was obtained from a sociodemographic questionnaire

Dissecting the Shared Genetic Architecture of Suicide Attempt, Psychiatric Disorders, and Known Risk Factors

BACKGROUND: Suicide is a leading cause of death worldwide, and nonfatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both have substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders. METHODS: We conducted a genome-wide association study (GWAS) of 29,782 suicide attempt (SA) cases and 519,961 controls in the International Suicide Genetics Consortium (ISGC). The GWAS of SA was conditioned on psychiatric disorders using GWAS summary statistics via multitrait-based conditional and joint analysis, to remove genetic effects on SA mediated by psychiatric disorders. We investigated the shared and divergent genetic architectures of SA, psychiatric disorders, and other known risk factors. RESULTS: Two loci reached genome-wide significance for SA: the major histocompatibility complex and an intergenic locus on chromosome 7, the latter of which remained associated with SA after conditioning on psychiatric disorders and replicated in an independent cohort from the Million Veteran Program. This locus has been implicated in risk-taking behavior, smoking, and insomnia. SA showed strong genetic correlation with psychiatric disorders, particularly major depression, and also with smoking, pain, risk-taking behavior, sleep disturbances, lower educational attainment, reproductive traits, lower socioeconomic status, and poorer general health. After conditioning on psychiatric disorders, the genetic correlations between SA and psychiatric disorders decreased, whereas those with nonpsychiatric traits remained largely unchanged. CONCLUSIONS: Our results identify a risk locus that contributes more strongly to SA than other phenotypes and suggest a shared underlying biology between SA and known risk factors that is not mediated by psychiatric disorders