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PubMed2002

Effects of paraquat on essential antioxidant elements in osteogenic disorder Shionogi rat.

This study reports the effect of paraquat (PQ) on concentrations of four elements (Cu, Fe, Mg, Zn) in lung, kidney, spleen, liver, and heart of male osteogenic disorder Shionogi (ODS) rats, a strain not able to synthesize vitamin C. PQ significantly increased the Cu concentrations in lung, liver, and plasma, accompanied by a fall in renal levels. Fe levels were elevated in liver and spleen but lowered in plasma. PQ produced an increase in kidney Mg and a rise in liver Mg and Zn levels. Cardiac elemental levels were not affected by PQ treatment. PQ, a known oxidant, produced changes in tissue elements involved in antioxidant mechanisms.

Animals↗
PubMedDate not supplied

The influence of manganese on the distribution of essential trace elements. II. The tissue distribution of manganese, magnesium, zinc, iron, and copper in rats after chronic manganese exposure.

Two groups of male Sprague-Dawley rats were treated ip for 30 d with either 3.0 mg Mn/kg or an equal volume of 0.9% NaCl. Liver, kidney, pancreas, duodenum, spleen, testes, lungs, brain, skeletal muscle, bone, and blood were analyzed by atomic absorption spectrophotometry for the elements Mn, Mg, Zn, Fe, and Cu. Mn increased in all tissues except liver due to treatment. Bone and pancreas revealed the largest increases. In blood, increased Mn levels were almost totally accounted for by increases in the erythrocyte fraction. Subcellularly, all fractions (crude nuclear, crude mitochondrial, lysosomal, microsomal, and supernatant) revealed elevations in Mn content due to treatment. Mn did not concentrate selectively in any one subcellular fraction. Mn exposure was accompanied by decreased Zn levels in plasma and bone, decreased Mg levels in heart and bone, increased pancreatic Fe concentration, and increased Cu concentrations in plasma and several tissues.

Animals↗
PubMed1977

[Nickel--an essential trace element. 1. Influence of the supply of nickel on live weight gains, food consumption and body composition of growing pigs and goats].

Pigs and goats were used in long-term trials to investigate in which way supplements of 100 mug Ni per kg of a semisynthetic diet (control rations: 10 mg Ni per kg of the diet) would influence the rate of weight gains and food consumption and the body composition of the animals. A significant decline in the rate of weight increase was noted in the Ni-deficient animals. Ni-supplements added to the diet (10 mg/kg) increased the weight gains by 21% (goats) and 13% (pigs). In the present trial goats showed a more sensitive response to Ni-deficiency than pigs. Ni-deficiency did not affect the food consumption of neither the growing goats nor the growing pits. It was only during their lactation period that the Ni-deficient goats showed a statistically well-established decrease in food consumption. The level of Ni supply did not affect the crude protein, crude fat and crude ash content of the pigs.

Animal Feed↗
PubMed1978

[Nickel--an essential trace element. 3. Effect of nickel deficiency on reproductive performance in female animals].

A total of 26 Ni-deficient (less than 100 ppm Ni in the ration) breeding goats and their 30 kids and 24 corresponding control goats with 37 kids were used to investigate, over 6 experimental years, the influence of Ni-deficiency on the reproductive performance until weaning. Following the same arrangement, 7 and 6 mini sows, respectively, and their piglets (71 and 67) were studied. The following statistically secured results were obtained. Ni-deficiency resulted in reduced pregnancy rates (after one insemination) in animals that had revealed clear estrus symptoms. This caused delayed pregnancies and birth of offspring. The conception and abortion rates, the number of offspring and the sex ratio were not influenced significantly by Ni-deficiency. Intra-uterine Ni-deficiency reduced the birth weights and caused lower weight gains during the suckling period. Its influence proved stronger in the kids as compared to the mini piglets. Ni-deficiency caused the mortality of the offspring during the suckling period to increase significantly. The losses in the Ni-deficient kids and mini piglets were by 41 and 51%, respectively, higher than in the corresponding control animals.

Abortion, Veterinary↗
PubMed1993

Two essential regulatory elements in the human interferon gamma promoter confer activation specific expression in T cells.

Like interleukin 2 (IL-2), interferon gamma (IFN-gamma) is an early response gene in T cells and both are prototypical T helper cell type 1 (Th-1) lymphokines. Yet IL-2 and IFN-gamma production are independently regulated, as demonstrated by their differential expression in certain T cell subsets, suggesting that the regulatory elements in these two genes must differ. To explore this possibility, the 5' flank of the human IFN-gamma gene was analyzed. Expression of IFN-gamma promoter-driven beta-galactosidase reporter constructs containing 538 bp of 5' flank was similar to that by constructs driven by the IL-2 promoter in activated Jurkat T cells; expression nearly as great was observed with the construct containing only 108 bp of IFN-gamma 5' flank. These IFN-gamma promoter constructs faithfully mirrored expression of the endogenous gene, in that expression required activation both with ionomycin and PMA, was inhibited by cyclosporin A, and was not observed in U937 or THP-1 cells. The region between -108 and -40 bp in the IFN-gamma promoter was required for promoter function and contained two elements that are conserved across species. Deletion of 10 bp within either element reduced promoter function by 70%, whereas deletions in nonconserved portions of this region had little effect on promoter function. The distal conserved element (-96 to -80 bp) contained a consensus GATA motif and a potential regulatory motif found in the promoter regions of the GM-CSF and macrophage inflammatory protein (MIP) genes. Factors binding to this element, including GATA-3, were found in Jurkat nuclear extracts by electromobility shift assays and two of the three complexes observed were altered in response to activation. One or both of these motifs are present in the 5' flank of multiple, other lymphokine genes, including IL-3, IL-4, IL-5, and GM-CSF, but neither is present in the promoter of the IL-2 gene. The proximal conserved element (-73 to -48 bp) shares homology with the NFIL-2A element in the IL-2 promoter; these elements compete for binding of factors in Jurkat nuclear extracts, although the NFIL-2A element but not the IFN-gamma element binds Oct-1. Factors binding to this element in the IFN-gamma gene were present in extracts from resting and activated Jurkat T cells. However, by in vivo footprinting of intact cells, this element was protected from methylation only with activation.(ABSTRACT TRUNCATED AT 400 WORDS)

Base Sequence↗
PubMed1989

Research review: studies in the nutrition of elderly people with particular reference to essential trace elements.

Duplicate diet analysis, metabolic balance studies and the measurement of biochemical and haematological indices were used to assess the trace element and overall nutritional status of 24 apparently healthy and 20 housebound elderly subjects. The housebound subjects had suboptimal status (as compared with the healthy subjects) for nitrogen, zinc, copper, iron, selenium, calcium and phosphorus.

Aged↗
PubMed2002

Selenium as a 'nutraceutical': how to conciliate physiological and supra-nutritional effects for an essential trace element.

PURPOSE OF REVIEW: To review how selenium has been appreciated in nutrition and therapeutics for the last few decades. RECENT FINDINGS: Selenium is a powerful micronutrient constituting the active centre of about 20 eukaryotic proteins highly relevant in biochemistry, mostly for redox state-regulating properties. This element is now better recognized as a biologically important nutrient. Insufficient dietary intake for satisfying biological requirements in several physiological or pathological conditions has been demonstrated, and it is now established that inadequate intake has adverse consequences for disease susceptibility and the maintenance of optimal health. The 'recommended dietary allowances' for selenium actually seem inadequately defined considering not only the recent evolutions of selenium biochemistry, but also the way in which selenium requirements are estimated. Indeed, the element also seems active at supra-nutritional levels of dietary intake, mostly in the field of cancer prevention, and maybe also at pharmacological levels as an adjuvant treatment of some cancers. SUMMARY: Selenium perfectly illustrates the concept of 'nutraceutical' and the need for changing paradigms in nutrition. Indeed, intakes for satisfying physiological needs as reflected by classical selenium-dependent biochemical functions (mostly glutathione peroxidase activity) only explain a part of selenium biological potency. Other beneficial effects can be obtained at higher nutritional intakes, which in turn implies specified chemical forms and doses. Studies are under way to document these effects in a more complete and convincing manner.

Anticarcinogenic Agents↗
PubMed2003

A novel pseudoknot element is essential for the action of a yeast telomerase.

Telomerase contains an essential RNA, which includes the template sequence copied by the reverse transcription action of telomerase into telomeric DNA. Using phylogenetic comparison, we identified seven conserved sequences in telomerase RNAs from Kluyveromyces budding yeasts. We show that two of these sequences, CS3 and CS4, are essential for normal telomerase function and can base-pair to form a putative long-range pseudoknot. Disrupting this base-pairing was deleterious to cell growth, telomere maintenance, and telomerase activity. Restoration of the base-pairing potential alleviated these phenotypes. Mutating this pseudoknot caused a novel mode of shifting of the boundaries of the RNA template sequence copied by telomerase. A phylogenetically derived model of yeast TER structure indicates that these RNAs can form two alternative predicted core conformations of similar stability: one brings the CS3/CS4 pseudoknot spatially close to the template; in the other, CS3 and CS4 move apart and the conformation of the template is altered. We propose that such disruption of the pseudoknot, and potentially the predicted telomerase RNA conformation, affects polymerization to cause the observed shifts in template usage.

Base Pairing↗
PubMed1999

Identification of two essential sequence elements in the nonconsensus type II PatpB-290 plastid promoter by using plastid transcription extracts from cultured tobacco BY-2 cells.

In higher plants, plastid genes are transcribed by at least two types of DNA-dependent RNA polymerases. One of them is the well-known plastid-encoded prokaryotic type of polymerase that recognizes sigma(70)-type promoters consisting of -35 and -10 consensus elements. The other recently recognized RNA polymerase has been found to be encoded entirely in the nucleus, and it recognizes a completely different set of promoters, designated previously as nonconsensus type II (NCII) promoters. Here, we report the development of an in vitro transcription system using nonphotosynthetic plastids of cultured tobacco BY-2 cells. This system preferentially and accurately initiates transcription from NCII promoters. The conditions for in vitro transcription were optimized by using the tobacco PatpB-290 promoter, which has been found to be the most highly expressed NCII promoter in vivo. Analysis of in vitro transcription initiation in a series of PatpB-290 5' deletion constructs revealed that sequences upstream of nucleotide -41 do not influence the transcriptional activity of this promoter. A 43-bp region (nucleotides -35 to +8) was further analyzed by introducing single or multiple nucleotide substitutions into two regions (box I and box II) of high sequence conservation. We report here that the ATAGAA sequence comprising box II and the -11 to +4 region (relative to transcription initiation) in box I significantly influence the activity of this NCII promoter.

Base Sequence↗
PubMed1979

Manganese, an essential trace element for N2 fixation by Rhodospirillum rubrum and Rhodopseudomonas capsulata: role in nitrogenase regulation.

Nitrogenase (N(2)ase) from the photosynthetic bacterium Rhodospirillum rubrum can exist in two forms, an unregulated form (N(2)ase A) and a regulatory form (N(2)ase R), the latter being identified in vitro by its need for activation by a Mn(2+)-dependent N(2)ase activating system. The physiological significance of this Mn(2+)-dependent N(2)ase activating system was suggested here by observations that growth of R. rubrum and Rhodopseudomonas capsulata on N(2) gas (a condition that produces active N(2)ase R) required Mn(2+), but growth on ammonia or glutamate did not. Manganese could not be shown to be required for the biosynthesis of either nitrogenase or glutamine synthetase or for glutamine synthetase turnover, but it was required for the in vitro activation of N(2)ases from N(2) and glutamate-grown R. rubrum and R. capsulata cells. Chromatium N(2)ase, in contrast, was always fully active and did not require Mn(2+) activation, suggesting that only the purple nonsulfur bacteria are capable of controlling their N(2)ase activity by this new type of regulatory system. Although R. rubrum could not substitute Fe(2+) for Mn(2+) in the in vivo N(2) fixation process, Fe(2+) and, to a lesser extent, Co(2+) could substitute for Mn(2+) in the in vitro activation of N(2)ase. Electron paramagnetic resonance spectroscopy of buffer-washed R. rubrum chromatophores showed lines characteristic of Mn(2+). Removal of the Mn(2+)-dependent N(2)ase activating factor by a salt wash of the chromatophores removed 90% of the Mn(2+), which suggested a specific coupling of this metal to the activating factor. The data presented here all indicate that Mn(2+) plays an important physiological role in regulating the N(2) fixation process by these photosynthetic bacteria.

Ammonia↗