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PubMed1980

The value of sewage sludge to agriculture and effects of the agricultural use of sludges contaminated with toxic elements: a review.

The effects of organic matter, nitrogen, phosphorus and toxic elements in sewage sludges applied to agricultural land are reviewed. Organic matter may improve the structure and water holding capacity of poor soils and the nitrogen and phosphorus in sludge have fertiliser value. However, and important consideration in applying sludge to land is the limitation of addition of toxic elements and any beneficial effects are secondary to this. Crops can accumulate toxic elements from sludge-amended soils and where heavily contaminated sludges and excessive rates of application are used plants may accumulate concentrations which are phytotoxic. The extent of accumulation varies considerably with plant species and cultivar; cereals and legumes accumulating lower concentrations than leafy plants such as lettuce and spinach. Although guidelines limit the addition of toxic elements in sludges and soils, thus reducing the quantities of these elements accumulated by plants, total concentrations of toxic elements in soil provide no indication of their availability to plants. The procedures applied to the determination of the forms of elements in sludges and soils and attempts to relate forms extractable in a variety of reagents to their availability to plants have been discussed. The factors which influence the forms of nutrient and toxic elements, their long term availability and hence their accumulation by crops are also reviewed.

Agriculture↗
PubMed1996

Positive and negative elements contribute to the cell-specific expression of the rat dopamine beta-hydroxylase gene.

Dopamine beta-hydroxylase catalyzes the final step in noradrenaline synthesis and is expressed exclusively in noradrenergic and adrenergic cells. In order to identify elements within the dopamine beta-hydroxylase (DBH) gene which contribute to the regulation of tissue-specific expression, we have analyzed the expression of the rat DBH promoter by transient transfection in both DBH-expressing and non-expressing cell lines. We have found that 1 kilobase of the DBH promoter can direct expression of the luciferase reporter gene in the DBH-expressing PC12, CATH.a, and SK-N-SH cell lines, but not in the non-DBH-expressing C6 glioma or CA77 cell lines. This activity was localized to a region between -133 and -173 upstream of the transcription start site. This element, however, also directed expression in non-DBH-expressing cell lines, but was inhibited when sequences between -212 and -388 were included. This inhibitory region contains sequences homologous to a silencer element recently identified in the human DBH gene, and shares homology with other previously identified silencer elements. Gel retardation experiments demonstrate that the rat DBH inhibitory region and the silencer elements found in the rat sodium type II channel and SCG10 genes bind a similar factor. The region between -133 and -173, which contains a consensus cyclic AMP response element (CRE), was also found to be responsive to cAMP in both DBH-expressing and non-expressing cells. Inclusion of sequences between -173 and -190 diminished the cAMP induction in PC12 cells, and nearly abolished the induction in C6 and CA77 cells, suggesting the presence of an additional negative element which inhibits cAMP induction in non-DBH expressing cells. DNA binding assays using antibodies to CRE binding protein-related transcription factors identified ATF-1 binding to the rat DBH-CRE, and further suggest that inhibition of cAMP regulation may be due to inhibition of ATF-1 binding by an additional factor, which binds to the DBH promoter immediately upstream of the CRE. These results demonstrate the importance of both positive and negative regulatory elements in the regulation of tissue-specific expression of the rat DBH gene.

Analysis of Variance↗
PubMed1989

Element content in tissues of four rodent species sampled in the Geysers geothermal steamfield.

Liver and kidney tissue samples from four rodent species collected in the Geysers geothermal steamfield of northern California were analyzed for content of 28 elements. Element concentrations in samples from the developed region of the Geysers were compared with samples from undeveloped reference regions to determine the influence of geothermal power development on element content in small mammal tissues. Eight elements (B, Ca, Cu, Mg, Mn, P, Sr, Ti) were enriched in samples from the Geysers, 12 (Ag, Al, Co, Cr, Fe, K, Mo, Na, Ni, Pb, Si, Zn) were decreased within the Geysers, Ba and Li were inconclusive, and six (As, Be, Cd, Hg, Sn, V) were below the minimum analytical limits. The longest-lived species (Neotoma fuscipes) had the greatest occurrence of statistically significant differences in element content. Sites in grassland habitat produced more significant differences in element content than either chaparral or streamside habitats for samples from Peromyscus maniculatus. Peromyscus boylii and P. truei provided additional data, but no distinct advantages for element monitoring. The data indicate regional influences from geothermal power development on element levels in rodent tissues.

Journal Article↗
PubMed1990

Quantitative energy-filtered image analysis in cytochemistry. II. Morphometric analysis of element-distribution images.

A combination of energy-filtered electron microscopy (EFEM) and an image-analysis system (IBAS/2000) is used for a morphometric analysis of chemical reaction products in cells. Electron energy-loss spectroscopic element-distribution images are acquired from cytochemical reaction products in a variety of cellular objects: (1) colloidal thorium particles in extra-cellular coat material, (2) iron-containing ferritin particles in liver parenchymal cells, (3) barium-containing reaction products in endoplasmic reticulum stacks, (4) elements present in lysosomal cerium- and barium-containing precipitates connected with acid phosphatase (AcPase) or aryl sulphatase (AS) enzyme activity. Areas or area fractions are determined from such element-distribution images by application of an objective image segmentation method. By superposition of two or more element-distribution images, mutual element relations are qualitatively established in lysosomal cerium- and barium-containing precipitates connected with acid phosphatase (AcPase) or aryl sulphatase (AS) enzyme activity. By comparing electron spectroscopic images (ESI) with element-distribution images, the mutual contrast per element relations are quantitatively investigated. The obtained gain in resolution in such electron energy-loss spectroscopic element-distribution images will be explained and discussed.

Animals↗
PubMed1993

Tissue-specific regulatory elements of the Drosophila Gld gene.

Putative cis-acting regulatory elements immediately upstream of the Gld promoter were identified by comparative analysis of three Drosophila species. A 509 bp region containing these elements and the Gld promoter region was shown to confer tissue-specific regulation to a reporter gene similar to the pattern observed for Gld mRNA and protein. A dispersed repeat with a core motif of TTAGA was also capable of directing the expression of a reporter gene to several epidermally derived tissues in which GLD is normally expressed. These tissues include male and female somatic reproductive organs. The TTAGA elements and a palindromic element act antagonistically to block expression of reporter gene in some tissues. Previously reported mutations of the heat shock response element resulted in the creation of three TTAGA elements. This mutated hsp70 promoter directs expression of a reporter gene to many of the same tissues as does the Gld TTAGA elements. We have found TTAGA elements near the promoter of two other genes which show an identical expression pattern in the male ejaculatory duct as Gld and the mutant hsp70.

Animals↗
PubMed1995

Origin of a negative calcium response element in an ALU-repeat: implications for regulation of gene expression by extracellular calcium.

The negative calcium response element type 2 (nCARE) is a regulatory DNA sequence consisting of a palindromic core sequence and several upstream T residues, which was originally described in the 5' flank of the human PTH gene. The nCARE functions in an orientation-specific manner to inhibit PTH transcription in response to raised extracellular calcium levels. Here we report that the PTH nCARE lies within a hitherto unrecognized ALU-like element situated approximately 3.6 kB upstream of the human PTH gene transcriptional start site. Since ALU elements are repetitive DNA sequences, which are widely distributed throughout the human genome, we hypothesized that other nCARE elements might also exist. A search of the GenBank/EMBL databases with the nCARE core sequence confirmed this to be the case showing the presence of 111 copies of the nCARE in human/primate sequences. Analysis of the 7SL RNA sequence from which ALU elements derive also showed the presence of an nCARE "core" sequence immediately upstream of the poly-A+ tail. These data suggest that the nCARE is derived from retrotransposition of 7SL RNA and forms an integral part of many ALU elements; reverse transcription of the poly-A+ tail of 7SL RNA adds T residues, which on retrotransposition into genomic DNA with the core sequence, forms an ALU element containing a functional nCARE. Some of the genes associated with nCARE elements express products which are affected by extracellular calcium concentrations and work is in progress to determine the functional effects of nCARE at these sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed2005

Trace element pollution records in some UK lake sediments, their history, influence factors and regional differences.

Sediment cores were taken from six sites across the UK. Apart from Banbury Reservoir in London, all the other sites are relatively remote lakes. Trace elements Pb, Zn, Cu, Cd, Cr, Ni, Sn, As and V, major elements such as Fe, Mn, Ti and Al were analysed, and organic content measured as loss-on-ignition was determined in all of these cores. The result shows that these relatively remote sites have experienced enhanced atmospheric deposition of anthropogenically derived trace elements for over 100 years, and the contamination might start before industrialisation. Trace metal contamination remains the highest level at Banbury Reservoir showing "pollution source" influence. Despite the considerable reduction in atmospheric deposition in recent years, although some of the element concentrations in the surface sediments have declined, they are still much higher than their natural background values. In these sites, trace element pollution records have been influenced by many different factors. Redox condition could affect As distribution in the sediments. Sediment matrix could also affect trace element pollution signal. Apart from direct atmospheric deposition, the distributions of trace elements in the sediments have been affected by forestry activities and catchment erosion, and more contaminated soil in-wash could increase sediment pollution whilst less contaminated soil could dilute sediment pollution. In some sites, data suggest that catchment in-wash is an important source of elements for the lakes.

Environmental Monitoring↗
PubMed2004

Identification of regulatory elements in the Plasmodium falciparum genome.

There is little information regarding regulatory sequences in the newly sequenced genome of the malaria parasite, Plasmodium falciparum. Thus, for the first time, a bioinformatic strategy was utilized to identify regulatory elements in this genome using the P. falciparum heat shock protein (hsp) gene family as a model system. Our analysis indicates that the P. falciparum hsp genes do not contain standard eukaryotic regulatory elements. However, a novel G-rich regulatory element named the G-box was identified upstream of several P. falciparum hsp genes and the P. yoelii yoelii, P. berghei, and P. vivax hsp86 genes. Remarkably, the Plasmodium sp. G-boxes were required for maximal reporter gene expression in transient transfection assays. The G-box is not homologous to known eukaryotic elements, and is the best-defined functional element elucidated from Plasmodium sp. Our analysis also revealed several other elements necessary for reporter gene expression including an upstream sequence element, the region surrounding the transcription start site, and the 5' and 3' untranslated regions. These data demonstrate that unique regulatory elements are conserved in the genomes of Plasmodium sp., and demonstrate the feasibility of bioinformatic approaches for their identification.

3' Untranslated Regions↗
PubMed2004

Removal of biological and non-biological viral surrogates by spiral-wound reverse osmosis membrane elements with intact and compromised integrity.

The removal of bacteriophage MS2 and fluorescent-dyed polystyrene microspheres with intact and purposely compromised spiral-wound RO membrane elements was investigated. MS2 rejection with intact membrane elements was >99.9995%. A model developed for data evaluation revealed that the advective passage of MS2 through imperfections of intact membrane elements was <2 x 10(-5)% of the overall product water flow produced. The advective passage of MS2 and microspheres through a pinhole induced in one of the elements was 0.05-0.1% of the overall product water flow. Prolonged testing of both intact and compromised elements resulted in increased MS2 rejection corresponding to advective MS2 passage through membrane imperfections of <3 x 10(-7)% of the overall product water flow. The permeate flow rate obtained with an element with a larger pinhole was 5-13% greater than that of the intact element, and the corresponding rejection of MS2 and microspheres was similar to that observed for sodium chloride. The use of a cracked o-ring in the connection of the permeate tube to the element vessel end-cup resulted in advective passage of MS2 through the crack of <0.0001% of the overall permeate flow.

Fluorescent Dyes↗
PubMed1997

An improved method for finite element mesh generation of geometrically complex structures with application to the skullbase.

An automated method has been developed to generate finite element meshes of geometrically complex structures from CT images using solely hexahedral elements. This technique improves upon previous voxel-based mesh reconstruction approaches by smoothing the irregular boundaries at model surfaces and material interfaces. Over a range of mesh densities, RMS error in surface Von Mises stress was higher in the unsmoothed circular ring models (0.11-0.24 MPa) than in the smoothed models (0.080-0.15 MPa) at each mesh density. The element-to-element oscillation in surface element stress, as measured by the average second spatial derivative of Von Mises stress along the outer surface of the ring, was higher in the unsmoothed models (11.5-15.0 kPa mm-2) than in the smoothed models (4.0-6.8 kPa mm-2). Similarly, in a human skullbase model, the element-to-element oscillation in surface Von Mises stress was higher in the unsmoothed model (5.52 kPa mm-2) than in the smoothed model (1.83 kPa mm-2). Using this technique, finite element models of complex geometries can be rapidly reconstructed which produce less error at the surface than voxel-based models with discontinuous surfaces.

Biomechanical Phenomena↗
PubMed1983

Freeze-fracture analysis of phloem structure in plant tissue cultures. I. The sieve element reticulum.

During the differentiation of phloem sieve elements, the endoplasmic reticulum undergoes unique modifications to form the sieve element reticulum (SER) which persists in mature, functioning sieve tubes. Cisternae of the SER lack ribosomes and are restricted to the periphery of the sieve element at late stages of development. Some of the SER is seen as single cisternae that are in close contact with the sieve element plasma membrane. Thin sections and freeze-fracture images of sieve elements formed in tissue cultures demonstrate that the SER consists of both single cisternae and regions of stacked cisternae at some stages of maturity. The unstacked regions of the SER are continuous with the cisternae of the stacked regions. In freeze-fracture images the single cisternae adjacent to the plasma membrane are seen to be fenestrated and the openings allow continuity between the plasma membrane and the cell lumen. It is concluded that the interface between the SER and the plasma membrane of the sieve element serves to allow membrane functions such as proton efflux, proton-sucrose cotransport and compensating movements of ions to occur in a microenvironment that is separated from the moving translocation stream in the sieve element lumen. Passage of water and translocated solutes from the plasma membrane or the SER/PM interface to the interior of the cell is enhanced by the openings in the fenestrated regions of the SER. It is suggested tha the SER may also play a role in channeling ATP from mitochondria associated with the SER to the proton-pumping ATPase in the plasma membrane and that the SER may function in the uptake and release of potassium ions in the sieve element.

Brassica↗
PubMed1998

Release of elements from dental casting alloys into cell-culture medium over 10 months.

OBJECTIVE: The release of elements from eight types of commonly used dental casting alloys into cell-culture medium was measured over a 10-month period. The release of elements was determined to provide information about the long-term biological risk these alloys may pose to the oral tissues. The current work extends previous studies of shorter time periods, and is more relevant to the in vivo situation, where dental alloys are present intraorally for years. METHOD: The alloys were Au-, Ag-, Pd-, and Ni-based with nobilities ranging from 0 to 95 at.%. Alloy samples (n = 12) were exposed to cell-culture medium. The medium was changed every 30 days for 10 months. Elemental release into the medium was measured by means of atomic absorption spectrophotometry. Differences in mass release were determined using ANOVA and Tukey multiple comparison intervals (alpha = 0.05). RESULTS: The release of elements continued through 10 months, and it appeared that the release was constant throughout most of the experiment. Higher initial rates were suspected but not verified. Most alloys reached a constant rate after < 100 days of exposure to the medium. Long-term element release was not generally intuitive based on the amount of an element in an alloy or the overall nobility of the alloy. Total mass lost over the 10-month period ranged from < 2 micrograms/cm2 for the Au-Pd alloy to 55 micrograms/cm2 for the Au-Ag-Cu alloy (Tukey interval at alpha = 0.05 was 0.8 microgram/cm2). By comparison, pure Cu lost 4500 micrograms/cm2 during this period. SIGNIFICANCE: Tests which assess biological risk from elemental release must consider longer-term release because elemental release continues for extended periods. Longer-term mass loss from a given alloy is often not intuitive based on its overall composition or noble metal content.

Analysis of Variance↗
PubMed2003

Particulate and dissolved elemental loads in the Kuji River related to discharge rate.

In order to investigate influences of discharge rates on fluvial transport behavior of elements in the Kuji River, Japan, suspended and dissolved phase concentrations in the river water were measured together with the water flow rates. The concentrations of suspended particulate matter (SPM) increased by two or three orders of magnitude with the water discharge, and also had seasonal variations. Adsorptive elements or heavy metal elements, which tend to form insoluble compounds, were present generally as suspended forms in the river waters, and their dissolved form concentrations tended to increase with the water discharge. On the other hand, non-adsorptive elements such as alkali and alkaline-earth elements were present as dissolved forms under a normal flow rate condition, but equivalent quantity of suspended species also occurred under a high flow condition. In this case, the dissolved form concentrations decreased with the water discharge. Characterization of SPM with analyses of chemical compositions, scanning electron microscopy (SEM) and X-ray diffractometry (XRD) indicated that clay mineral such as montmorillonite would be the main carrier material of trace and major elements during the fluvial transport in the Kuji River. Variations of contents of selected elements in SPM with the water discharge indicated that river bottom sediments, which are probably potential sources of SPM added due to high water flow rates, would be different in chemical compositions from SPM floating under a normal flow condition. Variations of chemical compositions of SPM as well as of suspended or dissolved form concentrations of elements in the river waters were formulated as a function of the water discharge rates.

Environmental Monitoring↗
PubMed2000

The COUP-adjacent repressor (CAR) element participates in the tissue-specific expression of the ovalbumin gene.

The ovalbumin (Ov) gene is an excellent model for the study of tissue-specific gene regulation as it is only active in the estrogen-stimulated oviduct. Previous studies have demonstrated that the negative regulatory element (NRE) in the Ov gene 5'-flanking region is responsible for silencing the gene in oviduct in the absence of steroids. Linker scanning analysis defined an element within the NRE designated the COUP-adjacent repressor (CAR) element as a repressor of Ov gene expression. However, the role of the CAR element in non-oviduct tissues has not been addressed. Using transient transfection analysis of various Ov 5'-flanking region constructs into the estrogen-responsive chicken hepatocyte cell line LMH/2A, we demonstrate that Ov gene expression is not induced by estrogen and that an active repressor element exists in the NRE. Deletion analysis indicates that the region from -134 to -87, which includes the CAR element, mediates this repression. Mutation of the CAR element relieves repression, leading to high levels of gene expression. These data support a model where the inhibition of Ov gene expression in non-oviduct cells is a combination of the lack of essential positive factors and the presence of an active repressor, which binds to the CAR element.

Animals↗
PubMed1998

A cis-acting regulatory element that affects the alternative splicing of a muscle-specific exon in the mouse NCAM gene.

The pre-mRNA encoding the neural cell adhesion molecule (NCAM) is spliced to generate NCAM isoforms containing the muscle-specific domain (MSD) during myogenesis. Utilizing chimeric NCAM minigenes, we searched for cis-acting elements that contribute to the alternative selection of exon MSDb, one of the four exons encoding MSD, and identified an intronic cis-element located downstream of exon MSDb. The cis-element acted as a negative regulator for the selection of exon MSDb in nonmuscle fibroblasts but not in myoblasts, that are already destined to differentiate into muscle cells. The suppressive effect of this cis-element on the selection of exon MSDb was released in the process of myogenesis. When MyoD was co-expressed with a minigene containing this element in fibroblasts, the suppressive effect of the cis-element was released as the cells underwent differentiation. We propose that this cis-element contributes at least as one of the regulatory elements in the differentiation state-dependent selection of MSD exons in vivo.

Alternative Splicing↗
PubMed2001

Elemental concentrations in different species of seaweeds from Loreto Bay, Baja California Sur, Mexico: implications for the geochemical control of metals in algal tissue.

Concentration levels of 21 elements were analyzed by instrumental neutron activation analysis (Rb, Cs, Ca, Sr, Ba, Sc, Cr, Fe, Co, Ni, Zn, Se, As, Sb, Th, U, Br, Hf, Ta, Zr, and Ag) in seven different seaweed species (Codium cuneatum, Sargassum sinicola, Padina durvillaei, Laurencia johnstonii, L. papillosa, Gracilaria pachidermatica and Hypnea pannosa), collected in a shallow coastal zone from Bahia de Loreto, Baja California Sur, Mexico. Measured concentrations in algal tissue spanned almost eight orders of magnitude (from 2.0 x 10(-3) microg g(-1) for Hf to 1.2 x 10(5) microg g(-1) for Ca). Ca was consistently the most abundant element in all analyzed seaweeds, followed by Fe and Sr. Brown algae showed a tendency to incorporate higher concentrations of elements than red and green algae. Additionally, there were significant linear correlations (P < 0.05 to P < 0.001) between a total of 76 different pairs of elements, some of them (e.g. Rb-Ni, Rb-Ag, Sc Cr, Sc-Fe, Sc Ni, Sc Hf, Cr Fe, Fe Ni, Fe-Hf and Ni-Th) highly correlated (r2 > 0.900). A significant correlation (r2 = 0.701, n = 18, P < 0.001) exists between our measurements in the tissue of algae and their corresponding average elemental concentrations in oceanic water from the North Pacific Ocean. Hence, overall elemental abundance in algal tissue apparently is controlled by the elemental abundance in oceanic water, whereas metabolic processes as well as environmental factors relevant to each region modify the final concentration of a given element in the body of a macroalgae.

Environmental Monitoring↗
PubMed1999

The EGF response element in the prolactin promoter.

Epidermal growth factor (EGF) increases prolactin gene expression in GH4 cells, but the promoter element(s) required for this response has not been clearly defined. We identified a bipartite element - 96/ - 87, - 76/ - 67 in the rat proximal promoter that is essential for EGF signaling using deletion and linker-scanning mutants of the prolactin promoter. This element was active in either normal or inverted orientation when transferred to a heterologous promoter (mammary-tumor virus). We had previously identified this element as the cAMP/insulin response element of the prolactin promoter. However, the effects of EGF are additive with the responses to insulin or cAMP implying that EGF activated prolactin gene transcription by a mechanism different from insulin or cAMP. The EGF response element of the prolactin promoter is a recognition sequence for the Ets-related family of transcription factors and Ets-related factors have been shown to bind this element. Expression of the DNA-binding domain of c-Ets-1, which acts as a dominant negative inhibitor of Ets-related transcription factors, reduces EGF-increased prolactin-CAT expression 65% in GH4 cells. Thus, both EGF and insulin may signal through Ets-related transcription factors to activate prolactin gene transcription at the same response element in the prolactin proximal promoter.

Animals↗
PubMed2000

Speciation of elements in NIST particulate matter SRMs 1648 and 1650

X-ray absorption fine structure (XAFS) spectra for S, Cl, V, Cr, Mn, Cu, Zn, As, Br, Cd and Pb and Mossbauer spectra for Fe have been obtained for two National Institute of Standards and Technology (NIST) particulate matter (PM) standard reference materials (SRMs): urban PM (SRM 1648) and diesel PM (SRM 1650). The spectral data, complemented by information on elemental concentrations from proton-induced X-ray-emission (PIXE) spectroscopy, were used to interpret the speciation of these elements in these complex materials. It appears that all the metallic elements investigated occur in oxidized forms, principally as sulfates in the diesel PM SRM and as sulfates, oxides, and possibly other forms (e.g. clays?) in the urban PM. A minor fraction of the sulfur and major fractions of the halogens, Cl and Br, occur as organosulfide (thiophene) and organohalide occurrences, respectively, that must be associated with the abundant carbonaceous matter that constitutes the major component of the two PM SRMs. Most of the sulfur, however, occurs as sulfate in the urban PM and as bisulfate in the diesel PM. In addition, elemental oxidation states have been determined directly by the spectroscopic techniques. Such information is often the key parameter in determining the toxicity and solubility of specific elements in PM, both of which are important in understanding the threat that such elements may pose to human health. For the two HAP elements, Cr and As, for which the toxicity depends greatly on oxidation state, the XAFS data showed that both elements are present in both SRMs predominantly in the less toxic oxidation states, Cr(III) and As(V). The potential of the XAFS spectra for use as source apportionment signatures is illustrated by reference to chromium, which exists in these two PM SRMs in very different forms.

Journal Article↗