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PubMed2006

Solar rotation effects on the thermospheres of Mars and Earth.

The responses of Earth's and Mars' thermospheres to the quasi-periodic (27-day) variation of solar flux due to solar rotation were measured contemporaneously, revealing that this response is twice as large for Earth as for Mars. Per typical 20-unit change in 10.7-centimeter radio flux (used as a proxy for extreme ultraviolet flux) reaching each planet, we found temperature changes of 42.0 +/- 8.0 kelvin and 19.2 +/- 3.6 kelvin for Earth and Mars, respectively. Existing data for Venus indicate values of 3.6 +/- 0.6 kelvin. Our observational result constrains comparative planetary thermosphere simulations and may help resolve existing uncertainties in thermal balance processes, particularly CO2 cooling.

Journal Article↗
PubMed1999

Magnetic lineations in the ancient crust of mars

The Mars Global Surveyor spacecraft, in a highly elliptical polar orbit, obtained vector magnetic field measurements above the surface of Mars (altitudes >100 kilometers). Crustal magnetization, mainly confined to the most ancient, heavily cratered martian highlands, is frequently organized in east-west-trending linear features, the longest extending over 2000 kilometers. Crustal remanent magnetization exceeds that of terrestrial crust by more than an order of magnitude. Groups of quasi-parallel linear features of alternating magnetic polarity were found. They are reminiscent of similar magnetic features associated with sea floor spreading and crustal genesis on Earth but with a much larger spatial scale. They may be a relic of an era of plate tectonics on Mars.

Journal Article↗
PubMed1996

Identification for mar mutants among quinolone-resistant clinical isolates of Escherichia coli.

Quinolone-resistant clinical Escherichia coli isolates were examined for mutations in the marRAB operon of the multiple antibiotic resistance (mar) locus. Among 23 strains evaluated, 8 were chosen for further study: 3 that showed relatively high levels of uninduced, i.e., constitutive, expression of the operon and 5 with variable responses to induction by salicylate or tetracyclines. The marR genes, specifying the repressor of the operon, cloned from the three strains constitutively expressing the operon did not reduce the level of expression of beta-galactosidase from a marO::lacZ transcriptional fusion and were therefore mutant; however, marR genes cloned from the five other clinical strains repressed LacZ expression and were wild type. All three mutant marR genes contained more than one mutation: a deletion and a point mutation. Inactivation of the mar locus in the three known marR mutant strains with a kanamycin resistance cassette introduced by homologous recombination reduced resistance to quinolones and multiple antibiotics. These findings indicate that mar operon mutations exist in quinolone-resistant clinical E. coli isolates and contribute to quinolone and multidrug resistance.

4-Quinolones↗
PubMed1997

Inhibition of the multiple antibiotic resistance (mar) operon in Escherichia coli by antisense DNA analogs.

The multiple antibiotic resistance operon (marORAB) in Escherichia coli controls intrinsic susceptibility and resistance to multiple, structurally different antibiotics and other noxious agents. A plasmid construct with marA cloned in the antisense direction reduced LacZ expression from a constitutively expressed marA::lacZ translational fusion and inhibited the induced expression of LacZ in cells bearing the wild-type repressed fusion. The marA antisense construction also decreased the multiple antibiotic resistance of a Mar mutant. Two antisense phosphorothioate oligonucleotides, one targeted to marO and the other targeted to marA of the mar operon, introduced by heat shock or electroporation reduced LacZ expression in the strain having the marA::lacZ fusion. One antisense oligonucleotide, tested against a Mar mutant of E. coli ML308-225, increased the bactericidal activity of norfloxacin. These studies demonstrate the efficacy of exogenously delivered antisense oligonucleotides targeted to the marRAB operon in inhibiting expression of this chromosomal regulatory locus.

Cloning, Molecular↗
PubMed1995

Regulation of the multiple antibiotic resistance (mar) regulon by marORA sequences in Escherichia coli.

The mar operon and adjacent sequences were subcloned on a low-copy-number plasmid to identify essential regulatory elements. A 1.1-kbp fragment containing 133 bp of the operator-promoter region (marO), the full marRA gene sequences, and only 10 of 72 marB codons provided a dela mar strain with normal repressibility and inducibility and the ability to beget mar constitutive mutants.

Bacterial Proteins↗
PubMed1997

Chicken MAR-binding protein ARBP is homologous to rat methyl-CpG-binding protein MeCP2.

Here, we describe the cloning and further characterization of chicken ARBP, an abundant nuclear protein with a high affinity for MAR/SARs. Surprisingly, ARBP was found to be homologous to the rat protein MeCP2, previously identified as a methyl-CpG-binding protein. A region spanning 125 amino acids in the N-terminal halves is 96.8% identical between chicken ARBP and rat MeCP2. A deletion mutation analysis using Southwestern and band shift assays identified this highly conserved region as the MAR DNA binding domain. Alignment of chicken ARBP with rat and human MeCP2 proteins revealed six trinucleotide amplifications generating up to 34-fold repetitions of a single amino acid. Because MeCP2 was previously localized to pericentromeric heterochromatin in mouse chromosomes, we analyzed the in vitro binding of ARBP to various repetitive sequences. In band shift experiments, ARBP binds to two chicken repetitive sequences as well as to mouse satellite DNA with high affinity similar to that of its binding to chicken lysozyme MAR fragments. In mouse satellite DNA, use of several footprinting techniques characterized two high-affinity binding sites, whose sequences are related to the ARBP binding site consensus in the chicken lysozyme MAR (5'-GGTGT-3'). Band shift experiments indicated that methylation increased in vitro binding of ARBP to mouse satellite DNA two- to fivefold. Our results suggest that ARBP/MeCP2 is a multifunctional protein with roles in loop domain organization of chromatin, the structure of pericentromeric heterochromatin, and DNA methylation.

Amino Acid Sequence↗
PubMed2005

MARS: microarray analysis, retrieval, and storage system.

BACKGROUND: Microarray analysis has become a widely used technique for the study of gene-expression patterns on a genomic scale. As more and more laboratories are adopting microarray technology, there is a need for powerful and easy to use microarray databases facilitating array fabrication, labeling, hybridization, and data analysis. The wealth of data generated by this high throughput approach renders adequate database and analysis tools crucial for the pursuit of insights into the transcriptomic behavior of cells. RESULTS: MARS (Microarray Analysis and Retrieval System) provides a comprehensive MIAME supportive suite for storing, retrieving, and analyzing multi color microarray data. The system comprises a laboratory information management system (LIMS), a quality control management, as well as a sophisticated user management system. MARS is fully integrated into an analytical pipeline of microarray image analysis, normalization, gene expression clustering, and mapping of gene expression data onto biological pathways. The incorporation of ontologies and the use of MAGE-ML enables an export of studies stored in MARS to public repositories and other databases accepting these documents. CONCLUSION: We have developed an integrated system tailored to serve the specific needs of microarray based research projects using a unique fusion of Web based and standalone applications connected to the latest J2EE application server technology. The presented system is freely available for academic and non-profit institutions. More information can be found at http://genome.tugraz.at.

Algorithms↗
PubMed2004

Equipment review: the molecular adsorbents recirculating system (MARS).

The molecular adsorbents recirculating system (MARS) is a form of artificial liver support that has the potential to remove substantial quantities of albumin-bound toxins that have been postulated to contribute to the pathogenesis of liver cell damage, haemodynamic instability and multi-organ failure in patients with acute liver failure (ALF) and acute-on-chronic liver failure (AoCLF). These toxins include fatty acids, bile acids, tryptophan, bilirubin, aromatic amino acids and nitric oxide. Data from controlled clinical trials are limited so far. One of two studies performed on small numbers of patients with AoCLF suggest a survival benefit, but no controlled data are available in the ALF setting. Our preliminary experience with MARS therapy, instituted late in the clinical course of five patients with severely impaired liver function, including three with AoCLF precipitated by sepsis and two with liver dysfunction due to sepsis in the absence of pre-existing chronic liver disease, indicates some clinical efficacy. However, the overall survival rate (1 of 5; 20%) remained poor. More data obtained from larger cohorts of patients enrolled in randomised controlled studies will be required in both the AoCLF and ALF settings to identify categories of liver failure patients who might benefit most from MARS treatment, to ascertain the most appropriate timing of intervention and to determine the overall impact on outcome, including cost-effectiveness.

Humans↗
PubMed1996

The chicken lysozyme gene 5' MAR and the Drosophila histone SAR are electroelutable from encapsulated and digested nuclei.

Cultured chicken cells were encapsulated in agarose microbeads, lysed in a near-physiological buffer and resulting encapsulated nuclei were digested with a restriction enzyme and electroeluted. After removal of approximately 97% of the chromatin, the nuclear lamina, residual nucleoli and an internal nuclear network remained. The majority of nascent RNA was also recovered in digested and electroeluted nuclei. Surprisingly, however, the chicken lysozyme gene 5' MAR was quantitatively electroeluted from digested nuclei of expressing and non-expressing cells, as well as the promoter region and the coding sequence. When encapsulated nuclei were digested partially, the proportion of elutable 5' MAR chromatin was comparable to that of elutable bulk chromatin. Furthermore, after digestion of encapsulated nuclei from Drosophila Kc cells, the histone SAR was electroeluted to the same extent as bulk chromatin. We conclude that the lysozyme gene 5' MAR and the histone SAR are not permanently attached to a nuclear matrix or scaffold.

Animals↗
PubMed2006

Examining substrate uptake patterns of Rhodocyclus-related PAO in full-scale EBPR plants by using the MAR-FISH technique.

While recognised as the important population responsible for enhanced biological phosphorus removal (EBPR), detailed knowledge on the physiology of Rhodocyclus-related polyphosphate accumulating organisms (PAO) has yet to be grasped. The objective of this study was to examine the in situ substrate uptake patterns of Rhodocyclus-related PAO present in full-scale EBPR plants by the combined technique of microautoradiography-fluorescent in situ hybridization (MAR-FISH). The presence of these PAO in the four investigated plants was confirmed by FISH and they constituted 17%, 9%, 8%, and 7% of the sludge community. By using MAR-FISH technique, Rhodocyclus-related PAO in all the plants demonstrated similar anaerobic substrate uptake patterns. They were capable of assimilating acetate, aspartate and glutamate under anaerobic condition but they showed negative uptake with palmitate. A significant fraction of the MAR-positive cells assimilated acetate, aspartate or glutamate was found to be Rhodocyclus-related PAO. Dual staining with DAPI and FISH showed that these PAO also accumulated polyphosphate aerobically with aspartate and glutamate as carbon source. The ability of assimilating amino acids besides acetate strongly indicates the versatile physiology of Rhodocyclus-related PAO, which could benefit them to achieve predominance in EBPR activated sludge.

Environmental Restoration and Remediation↗
PubMed2000

The MAR-binding protein SATB1 orchestrates temporal and spatial expression of multiple genes during T-cell development.

SATB1 is expressed primarily in thymocytes and can act as a transcriptional repressor. SATB1 binds in vivo to the matrix attachment regions (MARs) of DNA, which are implicated in the loop domain organization of chromatin. The role of MAR-binding proteins in specific cell lineages is unknown. We generated SATB1-null mice to determine how SATB1 functions in the T-cell lineage. SATB1-null mice are small in size, have disproportionately small thymi and spleens, and die at 3 weeks of age. At the cellular level, multiple defects in T-cell development were observed. Immature CD3(-)CD4(-)CD8(-) triple negative (TN) thymocytes were greatly reduced in number, and thymocyte development was blocked mainly at the DP stage. The few peripheral CD4(+) single positive (SP) cells underwent apoptosis and failed to proliferate in response to activating stimuli. At the molecular level, among 589 genes examined, at least 2% of genes including a proto-oncogene, cytokine receptor genes, and apoptosis-related genes were derepressed at inappropriate stages of T-cell development in SATB1-null mice. For example, IL-2Ralpha and IL-7Ralpha genes were ectopically transcribed in CD4(+)CD8(+) double positive (DP) thymocytes. SATB1 appears to orchestrate the temporal and spatial expression of genes during T-cell development, thereby ensuring the proper development of this lineage. Our data provide the first evidence that MAR-binding proteins can act as global regulators of cell function in specific cell lineages.

Aging↗
PubMed2000

Caught in the act: binding of Ku and PARP to MARs reveals novel aspects of their functional interaction.

Specific regions of eukaryotic genomic DNA that exhibit high-affinity binding to the nuclear matrix in vitro are called matrix attachment regions (MARs) and are implicated in the loop domain organization of chromatin. Small regions possessing high base unpairing potential within these MARs are referred to as base unpairing regions (BURs). BUR-affinity chromatographic separations of proteins from breast cancer cells yielded, almost exclusively, a mixture of poly (ADP-ribose) polymerase (PARP) and DNA-dependent protein kinase (DNA-PK), two nuclear enzymes that are implicated in the cellular response to DNA damage. Contrary to the long-held notion that PARP and Ku autoantigen, the DNA-binding heterodimeric subunit of DNA-PK, bind only to DNA ends, recently we have shown that both proteins individually bind BURs with high affinity and specificity in an end-independent manner. Furthermore, Ku autoantigen forms a molecular complex with PARP in the absence of DNA, and the physical association of these proteins synergistically enhanced their BUR-binding activity. Autoribosylation of PARP abolished its association with Ku autoantigen and BUR-binding activity. These findings have, for the first time, provided a molecular link toward elucidating the functional interaction between PARP and DNA-PK. The identification of MARs as their common binding target suggests a novel role for these enzymes in the modulation of chromatin structure and function.

Antigens, Nuclear↗
PubMedDate not supplied

[Isolation of Escherichia coli O157:H7 in storm drains in the city of Mar del Plata with bacterial contamination of fecal origin].

The present study was focused on the isolation and characterization of Escherichia coli, particularly the serotype O157:H7, from five combined-sewer outflows waters, which drain into the beaches of Mar del Plata. Seventeen hemolytic uremic syndrome cases were reported in Mar del Plata during the sampling period (May 1995-April 1996) in children between 9 month- and 5 year-old, and 3 deaths were recorded. E. coli identification was carried out by biochemical tests. E. coli was detected in 75% of the samples and a total of 98 strains were selected, with 11 sorbol non-fermenting strains. The strains belonged to the O1, O6, O44, O86a, O119 and O168 serogroups. As none of the known virulence factors was detected, strains could not be grouped within any of the diarrheagenic E. coli categories. None of the E. coli strains belonged to the O157:H7 serotype, but E. coli isolation showed fecal contamination in the combined-sewer outflows. Since their waters drain into beaches for recreational use, it is necessary to emphasize the detection of E. coli that would cause severe human illness. Bacterial pollution in combined-sewer outflows draining into Mar del Plata coasts might represent a high risk for human health.

Argentina↗
PubMed2003

Cytokines and liver failure: modification of TNF- and IL-6 in patients with acute on chronic liver decompensation treated with Molecular Adsorbent Recycling System (MARS).

Liver transplantation, considered today as the most effective treatment for end-stage liver diseases, can not always be performed on every patient affected with a liver disease. Patients with end-stage liver diseases, usually have high bilirubin, encephalopathy and renal failure. In these situations cytokines play an important role in different processes, from apoptosis to regeneration. The aim of this clinical study has been to analyse the action of new artificial liver system, called Molecular Adsorbent Recycling System (MARS) on cytokines metabolism in patients affected with acute on chronic liver failure. The results are intriguing because an increase of IL-6 and a decrease of TNF-alpha observed during MARS treatment. The study confirms the efficacy of MARS therapy in terms of homeostasis of the cytokines network and suggests an usefulness of monitoring their level during liver failure.

Adsorption↗
PubMed2005

Unregulated use of antibiotics in Siliguri city vis-a-vis occurrence of MAR bacteria in community waste water and river Mahananda, and their potential for resistance gene transfer.

The unregulated use of antibiotics, including therapeutic and prophylactic prescribing, in the fastest growing city of West Bengal, Siliguri, was studied indirectly from a random survey conducted on retail medicine sellers at their counters. Ciprofloxacin, ampicillin, norfioxacin and amoxycillin were the highest retailed antibiotics and 58% of the city pharmacies sold antibiotics even without prescriptions. To understand the influence of the extent of antibiotic use by the community on the collective bacterial flora in the aquatic environment, we have determined the fraction(s) of Standard Plate Count (SPC) bacteria resistant to different antibiotics and multiple antibiotic resistance (MAR) profile of resistant SPC isolates from two municipal open drains and Mahananda river water samples of Siliguri. Within the MAR groups of Drain I and Drain II samples, 37.44% and 77.43% respectively were resistant to all seven antibiotics (ampicillin, chloramphenicol, ciprofloxacin, kanamycin, netilmicin, streptomycin and tetracycline) used in the study. Twenty Gram-negative SPC MAR isolates were examined for the presence of plasmids. Antibiotic resistance was shown to be associated with a carriage of a 47 kb (D1QN - 9), 48 kb (D2QN - 14) and 49.4 and 3.6 kb (MR - 1) plasmids, which were transmissible to the Escherichia coli DH5alpha recipient. The rapid spread of antibiotic resistance genes in bacterial population as a consequence of indiscriminate use of antibiotics, which can be partly attributed to plasmid-mediated horizontal transfer was discussed.

Anti-Bacterial Agents↗
PubMed1989

Immunoglobulin kappa gene expression after stable integration. II. Role of the intronic MAR and enhancer in transgenic mice.

MOPC41 immunoglobulin kappa gene constructs have been stably introduced into the mouse germ line to investigate the effects of deleting the conserved intronic sequences on gene expression. Intact kappa genes containing 1.5 kilobase pairs of upstream and 8.5 kilobase pairs of downstream flanking sequences were highly expressed tissue-specifically, raising the total level of kappa mRNA in spleens severalfold in most transgenic animals. This high expression was often accompanied by marked suppression of endogenous kappa gene activity. Transgenes containing a deletion of the matrix association region (MAR) or both the MAR and enhancer were expressed tissue-specifically at mean levels only 2- and 3-fold lower, respectively, than that of intact transgenes. Therefore, while the intronic enhancer and MAR appear to play a quantitative role in gene expression, these sequences are not absolutely essential for transcriptional activation of rearranged kappa genes in a normal developmental environment.

Animals↗
PubMedDate not supplied

The direct IgG-MAR test (mixed antiglobulin reaction test): results and correlations with seminal analysis in 1176 men from infertile couples.

The direct IgG mixed antiglobulin reaction (IgG-MAR) test was carried out as a screening test and as a routine test of semen analysis in 1176 male patients from infertile couples. We correlated the results of the IgG-MAR test with the semen analysis parameters. The test was only positive in 3.1% of the cases; other Authors describe incidences of much higher positive results than ours, for which reason we emphasize that our patients had not previously undergone any kind of preliminary section. The positive IgG-MAR test proved to correlate significantly both with the number and motility of the spermatozoa, while there appeared to be no correlation between its positiveness and the other parameters of the seminal liquid.

Adult↗
PubMed1994

The risk assessment of faecal contamination by MAR indexing of Escherichia coli.

Multiple Antibiotic Resistance (MAR) index of faecal indicator bacterium Escherichia coli, isolated from water and sediment in the Bhavani river was employed to assess the quality of the river, and the risk of contamination. The MAR index of all the stations exceeded the high risk level (0.250) of contamination. The study of MAR index for individual isolates also showed high resistance against the tested antibiotics and it was found that these antibiotic resistant E. coli were distributed throughout the length of river sampled. It is concluded that the river is contaminated with faecal enteric bacteria, originating from high risk sources such as night soil, commercial poultry farms etc. It is implied that the quality of river water is not safe for drinking purpose and that adequate measures may be taken before use.

Anti-Bacterial Agents↗