Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.48 (transcriptase)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Using homologous recombination, both EKLF alleles in murine embryonic stem (ES) cells were inactivated. These EKLF-/- ES cells were capable of undergoing in vitro differentiation to form definitive erythroid colonies that were similar in size and number to those formed by wild-type ES cells. However, the EKLF-/- colonies were poorly hemoglobinized and enucleated erythrocytes in these colonies contained numerous Heinz bodies. Reverse transcriptase-polymerase chain reaction (RT-PCR) analyses revealed that adult and embryonic globin genes were appropriately regulated, with the exception of beta h1-globin, which continued to be expressed at a very low level. The ratio of adult beta-globin/alpha-globin mRNA in the mutant ES cells was 1/15 of that in wild-type ES cells. When the EKLF-/- cells were injected into blastocysts, they did not contribute at a detectable level to the mature erythrocyte compartment of the chimeric animals, based on analysis of glucose phosphate isomerase-1 (GPI-1) isozymes and hemoglobins that distinguish ES cell-derived erythrocytes from host blastocyst-derived erythrocytes. In contrast, semiquantitative RT-PCR analysis of RNA from reticulocytes of the same chimeric animals suggested that the ES cell-derived reticulocytes were present at a level of 6% to 8%. This indicated that the EKLF-/- erythrocytes in adult animals must be short-lived, apparently due to the imbalance of beta-versus alpha-globin chains, leading to the precipitation of excess alpha-globin chains to form Heinz bodies. Consistent with this hypothesis, the short life span was ameliorated by introduction into the EKLF-/- ES cells of a human LCR/gamma-globin gene, as evidenced by the presence of ES cell-derived reticulocytes as well as mature erythrocytes in the blood of the chimeric animals.
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PMID:A shortened life span of EKLF-/- adult erythrocytes, due to a deficiency of beta-globin chains, is ameliorated by human gamma-globin chains. 924 64

Allotetraploid plant species combine the genomes of related diploid species, but little is known about whether homologous genes from the diploid genomes are expressed, how they interact, or whether they evolve differently when in a common tetraploid nucleus. Polyploidy may lead to gene silencing, but few molecular characterizations of silenced genes encoding enzymes in polyploids and related diploids have been reported. Here we describe the PgiC genes in the tetraploid Clarkia gracilis and related diploid species, which are native from California to southern Washington. PgiC encodes the cytosolic isozyme of phosphoglucose isomerase (PGIC; EC 5.3.1.9). The gene was duplicated in the basal stock of Clarkia and now both genes, PgiC1 and PgiC2, are active in about half of the diploid species, whereas only PgiC1 is active in the others. Clarkia gracilis was found to have three PgiC genes: two PgiC1s and a PgiC2. Reverse-transcriptase-polymerase chain reaction (RT-PCR) experiments, starting with mRNAs prepared from seedling leaves of C. gracilis, showed that the three genes are expressed. Analysis of their sequences showed they are evolving at similar rates to their homologues and that they have the same intron-exon structure. The presence of an expressed PgiC2 in C. gracilis was unexpected because all related diploid species, including one identified as a parent, have only active PgiC1s. The donor of the PgiC2 is now presumed extinct, but parsimony analysis identified its phylogenetic position. None of the PgiC genes that were active when C. gracilis arose were silenced. A possible example of gene conversion involving a 300-nuclectide region of one PgiC1 and PgiC2 was identified, but it probably occurred in the diploid parental species rather than in C. gracilis. PgiC2 is the first known example of an active locus in a tetraploid plant species that is no longer expressed in its diploid relatives.
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PMID:MOLECULAR CHARACTERIZATION OF PgiC IN A TETRAPLOID PLANT AND ITS DIPLOID RELATIVES. 2856 13