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Query: UMLS:C0008272 (chlorosis)
 2,195 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Enlarged spleen, fever, increased susceptibility to infections, and thrombocytosis, are manifestations of iron deficiency which are relatively specific of pediatric patients. Iron deficiency anemia is part of everyday pediatrics. Patients are referred to the hematologist in the following situations: 1) Therapy is ineffective for one of the following reasons: the hypochromic anemia is not caused by iron deficiency (hemoglobinopathies); iron is less efficiently used because of transferrin deficiency or infectious, inflammatory or cancerous disease; iron therapy is inadequate either because of insufficient dosage or of suboptimal duration. 2) A relapse occurs in spite of adequate therapy. Before investigating the digestive tract, abnormal hemostasis. Osler-Weber-Rendu syndrome and pulmonary hemosiderosis should be considered. 3) Iron deficiency anemia is less common in adolescents. This condition, known as chlorosis, results mainly from increased needs, unbalanced diet, and onset of menses. In some cases no explanation is found but iron therapy leads to recovery. 4) Difficult problems arise in patients with complex anemias: iron deficiency with folic acid or vitamin B12 deficiency; hyposideremia complicating one of the hemoglobinopathies.
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PMID:[Iron-deficiency anemia. Hematologist's viewpoint]. 629 49

In light of the current interest in anorexia nervosa, this historical study explores the relationship of culture to age- and gender-specific symptomatologies. Between 1870 and 1920, chlorosis, a form of anemia, was widely reported in female adolescents in the United States. Diagnosis occurred on both the clinical and popular levels, yet neither the etiology nor the symptoms were precisely clear. Treatment generally included rest and large doses of iron salts. In large part, chlorosis was a cultural construction embedded in the context of Victorian medicine and family life. Physicians expected to see chlorosis in adolescent girls in the process of sexual maturation; girls learned to have the disease from family, friends, the popular press, and their doctors. Changes in diet and nutrition after 1900, coupled with increased understanding of ovarian function and iron deficiency anemia, provide only a partial explanation of the disease's eventual decline. By 1920, a changed social environment made chlorosis a social liability for girls and their mothers.
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PMID:Chlorotic girls, 1870-1920: a historical perspective on female adolescence. 675 9

Chlorosis was the first described by Lange in the 16th century as an anemia often found in adolescent girls and young women. Despite the recommendation by Sydenham in the 17th century that the condition be treated with iron supplements, chlorosis was classified among the hysterical diseases. By the end of the 19th century, the incidence of chlorosis apparently increased. It became an important subject of medical literature, but the true nature of the disease remained unknown. Many physicians believed that it was a result of a nervous disorder affecting various organ systems including the blood-forming organs. Iron medication became popular because of its therapeutic value, but its mode of action was controversial. Stockman in 1895 proposed that chlorosis was the result of a nutritional iron deficiency, but his view was largely ignored for decades. After World War I the incidence of chlorosis declined, and the disease ceased to be reported in the 1930s.
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PMID:Chlorosis: the rise and disappearance of a nutritional disease. 761 96

Arabidopsis thaliana (L.) Heynh. Columbia wild type and a root hair-less mutant RM57 were grown on iron-containing and iron-deficient nutrient solutions. In both genotypes, ferric chelate reductase (FCR) of intact roots was induced upon iron deficiency and followed a Michaelis-Menten kinetic with a Km of 45 and 54 microM FeIII-EDTA and a Vmax of 42 and 33 nmol Fe2+.(g FW)-1.min-1 for the wild type and the mutant, respectively. The pH optimum for the reaction was around pH 5.5. The approximately four fold stimulation of FCR activity was independent of formation of root hairs and/or transfer cells induced by iron deficiency. Iron-deficiency-induced chlorosis and the development of a rigid root habit disappeared when ferric chelate was applied to the leaves, while FCR activity remained unchanged. The time course of the responses to iron deficiency showed that morphological and physiological responses were controlled separately.
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PMID:Responses to iron deficiency in Arabidopsis thaliana: the Turbo iron reductase does not depend on the formation of root hairs and transfer cells. 776 49

Coronamic acid (CMA), an ethylcyclopropyl amino acid derived from isoleucine, functions as an intermediate in the biosynthesis of coronatine, a chlorosis-inducing phytotoxin produced by Pseudomonas syringae pv. glycinea PG4180. The DNA required for CMA biosynthesis (6.9 kb) was sequenced, revealing three distinct open reading frames (ORFs) which share a common orientation for transcription. The deduced amino acid sequence of a 2.7-kb ORF designated cmaA contained six core sequences and two conserved motifs which are present in a variety of amino acid-activating enzymes, including nonribosomal peptide synthetases. Furthermore, CmaA contained a spatial arrangement of histidine, aspartate, and arginine residues which are conserved in the ferrous active site of some nonheme iron(II) enzymes which catalyze oxidative cyclizations. The deduced amino acid sequence of a 1.2-kb ORF designated cmaT was related to thioesterases of both procaryotic and eucaryotic origins. These data suggest that CMA assembly is similar to the thiotemplate mechanism of nonribosomal peptide synthesis. No significant similarities between a 0.9-kb ORF designated cmaU and other database entries were found. The start sites of two transcripts required for CMA biosynthesis were identified in the present study. pRG960sd, a vector containing a promoterless glucuronidase gene, was used to localize and study the promoter regions upstream of the two transcripts. Data obtained in the present study indicate that CMA biosynthesis is regulated at the transcriptional level by temperature.
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PMID:The biosynthetic gene cluster for coronamic acid, an ethylcyclopropyl amino acid, contains genes homologous to amino acid-activating enzymes and thioesterases. 800 82

A synthetic siderophore, O-Trensox (L), has been designed and synthesized to improve iron nutrition of plants. The affinity for iron of this ligand [pFe(III) = 29.5 and pFe(II) = 17.9] is very high compared with EDTA. In spite of its high and specific affinity for iron, O-Trensox was found to be able to prevent, and to reverse, iron chlorosis in several plant species grown in axenic conditions. It also allows the iron nutrition and growth of Acer pseudoplatanus L. cell suspensions. The rate of iron metabolization was monitored by 59Fe radioiron. Ferritins, the iron storage proteins, are shown to be the first iron-labelled proteins during iron metabolization and to be able to further dispatch the metal. Using Fe(III)-Trensox, the rate of iron incorporation into ferritin was found to be higher than when using Fe-EDTA, but slower than with Fe-citrate, the natural iron carrier in xylem. During a plant cell culture, the extracellular concentrations of iron complex and free ligand were measured; changes in their relative amounts showed that the iron complex is dissociated extracellularly and that only iron is internalized. This suggests a high affinity for iron of a putative carrier on the plasmalemma. In contrast with Fe-citrate and Fe-EDTA complexes, Fe(III)-Trensox is not photoreducible. Its ability to induce radical damage as a Fenton reagent was tested using supercoiled DNA as target molecule. Unlike Fe-citrate and Fe-EDTA, Fe(II)-Trensox and Fe(III)-Trensox were proven to be harmless even during ascorbate-driven reduction, while Fe-EDTA and Fe-citrate generate heavy damage to DNA.
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PMID:Metabolization of iron by plant cells using O-Trensox, a high-affinity abiotic iron-chelating agent. 855 34

The uptake of iron in plants is a highly regulated process that is induced on iron starvation. In tomato, the mutant chloronerva exhibits constitutive expression of iron uptake responses and intercostal chlorosis. Biochemically, chloronerva is an auxotroph for nicotianamine, a key polyamine in plant iron uptake metabolism. The chloronerva gene has been fine-mapped onto the long arm of chromosome 1 in a large segregating tomato population and yeast artificial chromosome clones encompassing the region were isolated by using flanking markers. A cosmid contig containing the chloronerva gene was established, and complementing cosmids were identified by transformation into the mutant. The chloronerva transcript was identified by cDNA isolation using the complementing cosmids. The gene encodes a unique protein of 35 kDa. The mutant harbors a single base change compared with the wild type. Based on enzyme activity and sequence similarity to the coding DNA sequence of the purified barley enzyme the chloronerva gene encodes the enzyme nicotianamine synthase.
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PMID:Map-based cloning of chloronerva, a gene involved in iron uptake of higher plants encoding nicotianamine synthase. 1035 45

Xylella fastidiosa is a fastidious, xylem-limited bacterium that causes several economically important plant diseases, including citrus variegated chlorosis (CVC). X. fastidiosa is the first plant pathogen to have its genome completely sequenced. In addition, it is probably the least previously studied of any organism for which the complete genome sequence is available. Several pathogenicity-related genes have been identified in the X. fastidiosa genome by similarity with other bacterial genes involved in pathogenesis in plants, as well as in animals. The X. fastidiosa genome encodes different classes of proteins directly or indirectly involved in cell-cell interactions, degradation of plant cell walls, iron homeostasis, anti-oxidant responses, synthesis of toxins, and regulation of pathogenicity. Neither genes encoding members of the type III protein secretion system nor avirulence-like genes have been identified in X. fastidiosa.
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PMID:A genomic approach to the understanding of Xylella fastidiosa pathogenicity. 1105 Apr 42

A mutation in the Arabidopsis gene STARIK leads to dwarfism and chlorosis of plants with an altered morphology of leaf and cell nuclei. We show that the STARIK gene encodes the mitochondrial ABC transporter Sta1 that belongs to a subfamily of Arabidopsis half-ABC transporters. The severity of the starik phenotype is suppressed by the ectopic expression of the STA2 homolog; thus, Sta1 function is partially redundant. Sta1 supports the maturation of cytosolic Fe/S protein in Deltaatm1 yeast, substituting for the ABC transporter Atm1p. Similar to Atm1p-deficient yeast, mitochondria of the starik mutant accumulated more nonheme, nonprotein iron than did wild-type organelles. We further show that plant mitochondria contain a putative l-cysteine desulfurase. Taken together, our results suggest that plant mitochondria possess an evolutionarily conserved Fe/S cluster biosynthesis pathway, which is linked to the intracellular iron homeostasis by the function of Atm1p-like ABC transporters.
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PMID:A mutation of the mitochondrial ABC transporter Sta1 leads to dwarfism and chlorosis in the Arabidopsis mutant starik. 1115 31

Frequently, crop plants do not take up adequate amounts of iron from the soil, leading to chlorosis, poor yield and decreased nutritional quality. Extremely limited soil bioavailability of iron has led plants to evolve two distinct uptake strategies: chelation, which is used by the world's principal grain crops; and reduction, which is used by other plant groups. The chelation strategy involves extrusion of low-molecular-mass secondary amino acids (mugineic acids) known as 'phytosiderophores' which chelate sparingly soluble iron. The Fe(III)-phytosiderophore complex is then taken up by an unknown transporter at the root surface. The maize yellow stripe1 (ys1) mutant is deficient in Fe(III)-phytosiderophore uptake, therefore YS1 has been suggested to be the Fe(III)-phytosiderophore transporter. Here we show that ys1 is a membrane protein that mediates iron uptake. Expression of YS1 in a yeast iron uptake mutant restores growth specifically on Fe(III)-phytosiderophore media. Under iron-deficient conditions, ys1 messenger RNA levels increase in both roots and shoots. Cloning of ys1 is an important step in understanding iron uptake in grasses, and has implications for mechanisms controlling iron homeostasis in all plants.
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PMID:Maize yellow stripe1 encodes a membrane protein directly involved in Fe(III) uptake. 1120 43


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