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PubMed2001

Recognition and long-range interactions of a minimal nanos RNA localization signal element.

Localization of nanos (nos) mRNA to the germ plasm at the posterior pole of the Drosophila embryo is essential to activate nos translation and thereby generate abdominal segments. nos RNA localization is mediated by a large cis-acting localization signal composed of multiple, partially redundant elements within the nos 3' untranslated region. We identify a protein of approximately 75 kDa (p75) that interacts specifically with the nos +2' localization signal element. We show that the function of this element can be delimited to a 41 nucleotide domain that is conserved between D. melanogaster and D. virilis, and confers near wild-type localization when present in three copies. Two small mutations within this domain eliminate both +2' element localization function and p75 binding, consistent with a role for p75 in nos RNA localization. In the intact localization signal, the +2' element collaborates with adjacent localization elements. We show that different +2' element mutations not only abolish collaboration between the +2' and adjacent +1 element but also produce long-range deleterious effects on localization signal function. Our results suggest that higher order structural interactions within the localization signal, which requires factors such as p75, are necessary for association of nos mRNA with the germ plasm.

3' Untranslated Regions↗
PubMed2003

The pairing of X and Y chromosomes during meiotic prophase in the marsupial species Thylamys elegans is maintained by a dense plate developed from their axial elements.

Unlike eutherian males, pairing of the sex chromosomes in marsupial males during the first meiotic prophase is not mediated by a synaptonemal complex. Instead, a specific structure, the dense plate, develops during pachytene between the sex chromosomes. We have investigated the development and structural nature of this asynaptic association in males of the marsupial species Thylamys elegans by means of immunolabelling and electron microscopy techniques. Our results show that the behaviour of male marsupial sex chromosomes during first meiotic prophase is complex, involving modifications of their structure and/or composition. Pairing of the sex chromosomes and formation of the dense plate take place in mid pachytene, paralleling morphological changes in the sex chromosomal axial elements. Components of the central element of the synaptonemal complex were not found in the sex body, in agreement with ultrastructural studies that reported the absence of a canonical tripartite synaptonemal complex between male marsupial sex chromosomes. Interestingly, the dense plate is labelled with antibodies against the SCP3 protein of the lateral elements of the synaptonemal complex. Moreover, as sex chromosome axial elements decrease in mass throughout mid-late pachytene, the dense plate increases, suggesting that material moves from the axial elements to the dense plate. Additionally, both sex chromosome axial elements and the dense plate have proteins that are specifically phosphorylated, as revealed by their labelling with the MPM-2 antibody, indicating that they undergo a chromosome-specific regulation process throughout first meiotic prophase. We propose that the unique modifications of the composition and structure of the axial elements of the sex chromosomes in meiotic prophase may result in the prescription of synaptonemal complex formation between male marsupial sex chromosomes, where the dense plate is an extension of the axial elements of sex chromosomes. This replaces synapsis to maintain X and Y association during first meiotic prophase.

Animals↗
PubMed2003

Linear element formation and their role in meiotic sister chromatid cohesion and chromosome pairing.

Fission yeast does not form synaptonemal complexes in meiotic prophase. Instead, linear elements appear that resemble the axial cores of other eukaryotes. They have been proposed to be minimal structures necessary for proper meiotic chromosome functions. We examined linear element formation in meiotic recombination deficient mutants. The rec12, rec14 and meu13 mutants showed altered linear element formation. Examination of rec12 and other mutants deficient in the initiation of meiotic recombination revealed that occurrence of meiosis-specific DNA breaks is not a precondition for the formation of linear elements. The rec11 and rec8 mutants exhibited strongly impaired linear elements with morphologies specific for these meiotic cohesin mutants. The rec10 and rec16/rep1 mutants lack linear elements completely. The region specificity of loss of recombination in the rec8, rec10 and rec11 mutants can be explained by their defects in linear element formation. Investigation of the rec10 mutant showed that linear elements are basically dispensable for sister chromatid cohesion, but contribute to full level pairing of homologous chromosomes.

Chromatids↗
PubMed1997

Element density and the efficiency of binocular matching.

Constraints on binocular matching were investigated by comparing the thresholds for interocular correlation in random element displays for human and model observers, with element density manipulated as a parameter. The models consisted of ideal decision rules operating on the entire stimulus, only on the edges in the stimulus, or only on the sparse minority elements in the stimulus. The results indicate that the human visual system selectively attends to the stimulus edges or to the sparse elements under most circumstances. Efficiencies (human or model) were highest at very low element densities (approximately 20%) and decreased with increasing element density with a log-log slope of -0.5, indicating that dynamic random element stereograms at the traditional 50% element density are vastly undersampled.

Computer Simulation↗
PubMed2001

Polarization elements: a group-theoretical study.

The classification of polarization elements, the polarization affecting optical devices that have a Jones-matrix representation according to the type of eigenvectors they possess, is given a new visit through the group-theoretical connection of polarization elements. The diattenuators and retarders are recognized as the elements corresponding to boosts and rotations, respectively. The structure of homogeneous elements other than diattenuators and retarders are identified by giving the quaternion corresponding to these elements. The set of degenerate polarization elements is identified with the so-called null elements of the Lorentz group. Singular polarization elements are examined in their more illustrative Mueller-matrix representation, and, finally the eigenstructure of a special class of singular Mueller matrices is studied.

Journal Article↗
PubMed1993

Verbal self-reports about matching to sample: effects of the number of elements in a compound sample stimulus.

Adults' self-reports about their choices in a delayed matching-to-sample task were studied as a function of the number of elements (one, two, or three) in a compound sample stimulus. Signal-detection analyses were used to examine control of self-reports by the number of sample elements, by the speed and accuracy of choices reported about, and by several events contingent on self-reports. On each matching-to-sample trial, a sample element appeared as one of two comparison stimuli. Choice of the matching element, if made within 500 ms of the onset of the comparison stimuli, produced points worth money or chances in a drawing for money, depending on the subject. After each choice, subjects pressed either a "yes" or "no" button to answer a computer-generated query about whether the choice met the point contingency. The number of sample elements in the matching-to-sample task varied across trials, and events contingent on self-reports varied across experimental conditions. In Experiment 1, the conditions were defined by different combinations of feedback messages and point consequences contingent on self-reports, but self-reports were systematically influenced only by the sample-stimulus manipulation. Self-report errors increased with the number of sample elements. False alarms (inaccurate reports of success) were far more common than misses (inaccurate reports of failure), and false alarms were especially likely after choices that were correct but too slow to meet the point contingency. Sensitivity (A') of self-reports decreases as the number of sample elements increased. In addition, self-reports were more sensitive to choice accuracy than to choice speed. All subjects showed a pronounced bias (B'H) for reporting successful responses, although the bias was reduced as the number of sample elements increased and successful choices became less frequent. Experiment 2 demonstrated that the failure of point contingencies to influence self-reports in the first experiment was not due to a general ineffectiveness of the point consequences. Rates of inaccurate self-reports decreased when they resulted in point losses and increased when they resulted in point gains.

Adolescent↗
PubMed2002

[Alteration of the content of minor elements in apoptotic cells induced by anti-cancer drugs with synchronous radiation]

OBJECTIVE: To explore the change of content of minor elements and its biological implication in apoptotic processes. METHODS: The content of minor elements of apoptotic cells from breast cancer induced by anti-cancer drugs was quantitatively analysed with synchronous radiation X-ray fluorescence. RESULTS: Seven kinds of minor elements including Ti, Cr, Fe, Cu, Zn, Ga and Ge as well as five major elements P, S, Ca, Cl and K were detected in the apoptotic and control cells. The content of elements Zn and P in apoptotic cells after 48 h treatment with taxol and colchicine was significantly increased higher than that in the control cells P<0.05). The content of element Fe in 48 h treatment with taxol was significantly decreased lower than that in the control cells P<0.05). The same trend of change of elements was observed during the process of apoptotic cells death induced with VP-16 or cycloheximide. CONCLUSION: This results suggest that the elements Zn, Fe and P should be involved in apoptosis induced by anti-cancer drugs.

Journal Article↗
PubMed2005

Development of a finite element-based injury metric for pulmonary contusion part I: model development and validation.

Pulmonary contusion is the most commonly identified thoracic soft tissue injury in an automobile crash and after blunt chest trauma and affects 10-17% of all trauma admissions. The mortality associated with pulmonary contusions is significant and is estimated to be 10-25%. Thus, there is a need to develop a finite element model based injury metric for pulmonary contusion for the purpose of predicting outcome. This will enable current and future finite element models of the lung to incorporate an understanding of how stress and strain may be related to contusion injuries. This study utilizes 14 impacts onto male Sprague-Dawley rats. In 5 of these tests, a calibrated weight (46 g) is dropped from a height of 44 cm directly onto the lungs of intubated, anesthetized rats in situ. Contused volume is estimated from MicroPET scans of the lung and normalized on the basis of liver uptake of 18F-FDG. The lungs are scanned at 24 hours, 7 days, and 28 days (15 scans), and the contused volume is measured. In addition, 9 controlled mechanical tests on in situ rat lung are used for model development and validation. Identical impacts are performed on a finite element model of the rat lung. The finite element model is developed from CT scans of normal rat and scaled to represent average rat lung volume. First principal strain is chosen as a candidate injury metric for pulmonary contusion. The volume of contused tissue at the three time points measured using PET is compared to the strain level achieved by a corresponding volume in the finite element model. For PET scans (n=5 scans per time point), the average contusion volume was 4.2 cm3 at 24 hours, 2.8 cm3 at 7 days, and 0.39 cm3 at 28 days. These volumes were used to identify threshold peak first principal strain levels measured by the finite element model. Maximum first principal strain from the finite element model for the three volume levels (4.2, 2.8, and 0.39 cm3) was 3.5%, 8.8%, and 35% strain, respectively. Furthermore, the lung model exhibited exponential decay in principal strain threshold as more of the lung volume was considered, correlating to the precise and well defined volume of the contusion as it healed. The results of this study may be used to establish an injury metric to predict pulmonary contusion due to an impact to the lungs. The results may be used to improve finite element models of the human body, which may then be used to tune stiffnesses of interior components of automobiles and tune safety systems for maximum mitigation of this serious injury.

Journal Article↗
PubMed1996

Important elements of outpatient care: a comparison of patients' and physicians' opinions.

OBJECTIVE: To compare patients' and physicians' opinions on the importance of discrete elements of health care as determinants of the quality of outpatient care. DESIGN: Analysis of results of a mailed survey. SETTING: Community-based internal medicine practices. PARTICIPANTS: 74 general internists and 814 patients randomly selected from the practices of these internists. MEASURES: 125 elements of care that covered nine domains were identified: physician clinical skill, physician interpersonal skill, support staff, office environment, provision of information, patient involvement, nonfinancial access, finances, and coordination of care. Participants rated each element on its importance to high-quality care on a 4-point scale: 1 = not important; 2 = of medium importance; 3 = of high importance; and 4 = essential. Patients' and physicians' ratings were compared for individual elements of care and for elements aggregated into domains. RESULTS: Survey response rates were 93% for physicians and 60% for patients. In an element-by-element comparison of ratings, ratings by the two groups differed substantially for 58% of the attributes. The most striking difference was seen in the domain of provision of information (median ratings, 3.56 for patients and 2.85 for physicians; P < 0.001). Ratings by the two groups also differed in the domains of clinical skill (3.75 for patients and 3.35 for physicians; P < 0.001), nonfinancial access (3.00 for patients and 2.87 for physicians; P < 0.001), and finances (3.00 for patients and 2.80 for physicians; P = 0.006). When relative rankings of the domains were compared, both groups agreed that clinical skill is most important; however, patients ranked provision of information second in importance whereas physicians ranked it sixth. CONCLUSIONS: Patients and physicians agreed that the most crucial element of outpatient care is clinical skill, but they disagreed about the relative importance of other aspects of care, particularly effective communication of health-related information. These differences in perception may influence the quality of interactions between physicians and patients.

Adolescent↗
PubMed2000

Profiles of faecal output of rare earth elements and stable isotopic tracers of iron and zinc after oral administration.

The objectives of this study were to confirm the non-absorbability and the reproducibility of faecal excretion kinetics of orally administered rare earth elements, and to investigate the excretion profiles of rare earth elements and stable isotopic tracers of Fe and Zn to establish the extent to which rare earth element markers duplicate the behaviour of isotopic tracers. Two investigations were performed: (1) six healthy subjects consumed a solution containing five rare earth elements in amounts varying from 1 to 10 mg; (2) seven healthy subjects were given a standard solution labelled with Sm marker and (57)Fe tracer, and a meal labelled with Yb marker and (58)Fe and (70)Zn tracers. Individual faecal samples were collected and analysed to determine recoveries of rare earth elements and unabsorbed isotopic tracers. The mean values for recoveries were 94.1 (sd 4.5) % for the five rare earth elements, and 103 (sd 3.0) % and 99.8 (sd 2.8) % for Sm and Yb respectively. For Fe consumed with the solution, excretion kinetics of the rare earth element marker and unabsorbed tracers with cumulative collections of the first two and three faecal samples were identical, but endogenous excretion of Fe was significant in stools collected after the third. For Fe and Zn consumed with the meal, the excretion kinetics for the first two individual faecal samples and composites of sequential outputs were identical. Rare earth elements can be used as markers in studies of measurement of absorption. The dose of tracer required for the measurement of absorption would be reduced proportionally to the reduction of the period of faecal sampling, so that studies with stable isotopes would be more economical, thus enabling epidemiological investigations.

Administration, Oral↗
PubMed2000

Identification of Glucose-responsive and Insulin-responsive Elements in Promoter of Mouse ob Gene.

Glucose and insulin stimulate leptin gene expression in vitro and in vivo. To identify cis-elements that are responsible for the glucose and insulin effects, mouse 3T3-L1 adipocytes were transiently transfected with reporter constructs with serial deletions in mouse ob gene promoter. The cis-elements were identified with Gel mobility shift assays (GMSA), DNase I footprint assays and PCR mediated site-directed mutation assays. Transient transfections detected a negative cis-acting element, a glucose-responsive element (GLRE), and an insulin-responsive element (IRE) in the region from -1 719 bp to -1 452 bp of mouse ob gene. This region does not contain any known GLRE or IRE. GMSA identified a DNA binding protein which specifically binds a native probe prepared from mouse ob gene promoter (-1 719 bp/-1 452 bp), and the binding was repressed by glucose or insulin. DNase I footprint assays and PCR mediated site-directed mutations assays identified that the binding motif AGCAAAA, spanning -1 698 bp to -1 692 bp of the mouse ob gene promoter, was responsible for the effects of glucose and insulin on ob gene expression. These studies suggest that a negative cis-acting element is located between -1 719 bp and -1 452 bp of the mouse ob gene promoter, and glucose and insulin simulate mouse ob gene expression by repressing the binding of a transcription factor to this element. This element, AGCAAAA, spanning -1 698 bp to -1 692 bp is a novel GLRE and IRE.

Journal Article↗
PubMed2001

Teratogenicity test of dimethoate containing insecticide formulation and heavy elements (Cu, Cd) in chicken embryos after administration as single compounds or in combination.

The teratogenic effects of heavy elements (Cu-sulphate, Cd-sulphate) and a 38% dimethoate containing insecticide formulation (Bi 58 EC) were studied on chicken after administration as a single compounds or in combination. The test materials were injected directly into the airchamber with an injector on day 12 of incubation. Applied concentrations of heavy elements (Cu-sulphate, Cd-sulphate) were: 0.01-0.001% and the concentration of pesticide was 0.1%. Final volume was 0.1 ml/egg. Evaluation was done on day 19 of incubation. After the administration of heavy elements (Cu-sulphate, Cd-sulphate) on day 12 of incubation, the average body mass of embryos significantly decreased at all the treated dose groups as compared to the control. Embryonic mortality did not increase at all the two dose levels of Cu-sulphate and at 0.001% conc. of Cd-sulphate, while the highest concentration of Cd-sulphate killed 20% of embryos treated. The number of embryos with developmental anomalies did not differ markedly from the control. The simultaneous administration of heavy elements (Cu-sulphate, Cd-sulphate) and dimethoate containing insecticide a statistically significant reduction in embryonic body mass occurred at all the treated dose groups. The incidence of developmental anomalies was markedly higher after the simultaneous use of heavy elements (Cu-sulphate, Cd-sulphate) and dimethoate containing formulation than in tests based on the separate use of heavy elements. Embryonic mortality increased at all the treated dose groups and reached almost 20% rate. In summary, it can be established that the simultaneous administration of heavy elements (Cu-sulphate, Cd-sulphate) and the dimethoate containing insecticide caused higher toxicity with respect to test of individual toxicity of heavy elements.

Abnormalities, Drug-Induced↗
PubMed2004

[Correlation of mercury, selenium and other elements in the tissues of fishes from the regions at different mercury exposure level].

The contents of selenium and other elements in fish liver and muscle tissues collected from mercury polluted area of Wanshan, Guizhou province of China and non-known mercury polluted one of Beijing were determined with instrumental neutron activation analysis, and that of mercury was determined with atomic fluorescence spectrometry. The correlation among the determined elements, especially between mercury and selenium, in the fish tissues were studied. For most of the elements significant difference of elemental content was found between tissues of liver and muscle, and mostly the content in liver was higher than that in muscle. It was interesting to note that the average content of mercury in Guizhou fish liver was 25-fold higher than that in Beijing one, and 5-fold higher in Guizhou fish muscle than that in Beijing one. For most of the elements no significant difference on the average content was found between the same tissues of the two areas. The molar ratio of Hg/Se increased with the increasing of Hg content at the low Hg level, but the alteration trend became gently and reached to a higher constant value (about 0.2) at the higher Hg level. Only the element of bromine and rubidium was found to have strong linear correlation between the two different tissues of liver and muscle. Though certain correlation existed among the different elements of fish tissues from the two areas, the most significant and the closest one existed between the mercury and selenium of muscle tissue of Guizhou fishes. A closer correlation was also found between them of liver tissue of Guizhou fishes. As for Beijing fish tissues, the correlation of mercury and selenium only existed in liver but no correlation of them was found in muscle. Our results confirm the fact that a certain interaction exists between mercury and selenium in organisms including fish, and it is more evident as the mercury-exposed level is higher. Some significant correlation was also observed between other elements, such as potassium and sodium, cesium and rubidium, iron and zinc, in fish tissues and it could be well explained by their similar chemical and physical properties or their different biological functions.

Animals↗
PubMed2006

Chromosomal evolution of elements B and C in the Sophophora subgenus of Drosophila: evolutionary rate and polymorphism.

The locations of 77 markers along the chromosomal elements B (41 markers) and C (36 markers) of Drosophila subobscura, D. pseudoobscura, and D. melanogaster were obtained by in situ hybridization on polytene chromosomes. In comparisons between D. subobscura and D. pseudoobscura, 10 conserved segments (accounting for 32% of the chromosomal length) were detected on element B and eight (17% of the chromosomal length) on element C. The fixation rate of paracentric inversions inferred by a maximum likelihood approach differs significantly between elements. Muller's element C (0.17 breakpoints/Mb/million years) is evolving two times faster than element B (0.08 breakpoints/Mb/million years). This difference in the evolutionary rate is paralleled by differences in the extent of chromosomal polymorphism in the corresponding lineages. Element C is highly polymorphic in D. subobscura, D. pseudoobscura, and in other obscura group species such as D. obscura and D. athabasca. In contrast, the level of polymorphism in element B is much lower in these species. The fixation rates of paracentric inversions estimated in the present study between species of the Sophophora subgenus are the highest estimates so far reported in the genus for the autosomes. At the subgenus level, there is also a parallelism between the high fixation rate and the classical observation that the species of the Sophophora subgenus tend to be more polymorphic than the species of the Drosophila subgenus. Therefore, the detected relationship between level of polymorphism and evolutionary rate might be a general characteristic of chromosomal evolution in the genus Drosophila.

Animals↗
PubMed1991

Identification of a possible control element, Mt5, in the major noncoding region of mitochondrial DNA by intraspecific nucleotide conservation.

Nucleotide sequences throughout the whole major noncoding region of mitochondrial DNA of 18 subjects were determined. Previously identified control elements were classified into three groups according to the degree of intraspecific nucleotide conservations: strictly conserved elements (LSP, HSP, Mt3, Mt3 on H-strand, mtTF1-element for HSP), relatively conserved elements (CSB-III, Mt4 on H-strand, and mtTF1-element for LSP), and variable elements (TAS, CSB-I, CSB-II). Moreover, alignment of nucleotide conservations disclosed a stretch of conserved sequence (5'-ATGCTTACAAGCAAG-3', nucleotide number 16, 194-16,208, designated as Mt5 element) in the middle of the hypervariable segment. Nucleotide conservation of this element was not only intraspecific but also interspecific.

Base Sequence↗
PubMed1990

[Influence of metal elements in Pd alloys on the bonding to porcelain].

The influence of metal elements in three Pd alloys on the bonding to porcelain was examined. The high-temperature oxidation behavior of metal elements in alloys, structure and morphology of oxidation zones on the alloy surface and the appearance of bonding between alloy and fused porcelain at the interface were studied by ESCA and EPMA. From ESCA analysis, metal oxides such as PdO, SnO2, In2O3, CuO or Cu2O, Sb2O3 or Sb2O5 were formed on the surface of the alloy after degassing (preheating) and heating following casting. The amount of metal elements concentrated on the alloy surface was measured by their characteristic X-rays using area analysis of EPMA under the technical conditions of A) Acc. voltage 10 kV, Abs. current 40 nA, and B) Acc. voltage 20 kV, Abs. current 10 nA. Consequently, the amount of additive metal elements concentrated on the alloy surface which was detected in condition A) was larger than that detected in condition B). However, the amount of main element (Pd) concentrated on the alloy surface which was detected in condition A) was smaller than that detected in condition B). From the EPMA observation of the interface between alloy and fused porcelain, cross-section of alloys showed that the additive metal elements were oxidized in the alloy matrix, forming an internal oxide layer or particles. The structure and morphology of oxidation zones showed a significant difference between degassed and not-degassed alloys. Cross-sections inclined approximately 5 degrees 43' to the fusing boundary were also analyzed to enlarge the oxidation zones. This analytical technique effectively revealed the structure and morphology of oxidation zones. In conclusion, not only additive metal elements but also the main element at the surface of alloys play important roles on the bonding to porcelain. Degassing of the alloy was considered to an essential procedure to obtain the adequate bonding to porcelain.

Dental Bonding↗
PubMed1990

Element and compound matching-to-sample performance in pigeons: the roles of information load and training history.

Pigeons were trained to match color and line orientation element or compound samples in a symbolic matching-to-sample task. In subsequent test sessions with element and compound samples, there was an initial superiority of element matching for the element-trained group and of compound matching for the compound-trained group. This difference persisted over the course of 100 test sessions for the element-trained group, whereas element- and compound-matching accuracy converged for the compound-trained group. In a second experiment, in which sample duration was manipulated, element-matching accuracy was superior to compound-matching accuracy for both groups. Thus, element-matching accuracy was superior to compound-matching accuracy under conditions that rule out generalization decrement and training history as explanations. The data are interpreted as supporting the view that the dimensions of visual compound stimuli compete for a limited cognitive resource.

Animals↗
PubMed1987

Functional elements of the human U1 RNA promoter. Identification of five separate regions required for efficient transcription and template competition.

We have determined the structure of the human U1 snRNA promoter by microinjection of several mutant U1 templates into Xenopus laevis oocytes. These deletion templates were assayed for their ability to express mature U1 RNA and for their ability to compete for limiting transcription factors. We have mapped five separate regions, called promoter elements A, B, C, D, and E. Element A, located between positions -8 and -50, stimulates transcription 3- to 5-fold increases the accuracy of initiation; element B (between -50 and -80) fixes the site of initiation and stimulates transcription greater than 100-fold; element C (upstream of -129) increases the efficiency of element B 3- to 5-fold; element D (between -191 and -231) is an orientation-independent and partially position-independent enhancer responsible for a 100-fold stimulation of transcription; element E (between -335 and -393) increases the ability to compete with other snRNA genes 4-fold. All five promoter elements are required for effective competition with the wild-type U1 promoter suggesting that binding of transcription factor(s) to the complex is cooperative. The U1 RNA and some mRNA gene transcription complexes appear to share one or more transcription factors.

Animals↗