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Experiments using plasmid-borne gene fusions and direct RNA measurements have revealed that expression from the nifA gene is induced in Rhizobium meliloti when the external oxygen concentration is reduced to microaerobic levels. Induction occurs in the absence of alfalfa and in the presence of fixed nitrogen and does not require ntrC. The production of(More)
BACKGROUND Fanconi anaemia (FA) is a heterogeneous inherited disorder clinically characterised by progressive bone marrow failure, congenital anomalies and a predisposition to malignancies. OBJECTIVE Determine, based on correction of cellular phenotypes, whether XRCC2 is a FA gene. METHODS Cells (900677A) from a previously identified patient with(More)
We have previously demonstrated that the nifA promoter (nifAp) of Rhizobium meliloti is inducible under microaerobic conditions in the absence of alfalfa. Here we show that microaerobic activation of nifAp involves both cis- and trans-acting regulatory controls identical to those used symbiotically. The start site for nifA mRNA synthesis was found to be the(More)
Fanconi anemia (FA) is a rare inherited disorder clinically characterized by congenital malformations, progressive bone marrow failure and cancer susceptibility. At the cellular level, FA is associated with hypersensitivity to DNA-crosslinking genotoxins. Eight of 17 known FA genes assemble the FA E3 ligase complex, which catalyzes monoubiquitination of(More)
With advancing age, the mammalian thymus undergoes involution, a progressive loss of architectural integrity and lymphoid cellularity that results in reduced T lymphopoiesis. Thymic involution also is associated with extreme malnutrition and states of immune deficiency, such as active HIV infection, after chemotherapy, or during pregnancy. Immune recovery(More)
Thymic involution begins early in life and continues throughout adulthood, resulting in a decreased population of naive T cells in the periphery and a reduced ability to fight off newly encountered infectious diseases. We have previously shown that the first step of thymopoiesis is specifically blocked in aging. This block at the DN1 to DN2 transition and(More)
Transgenic mice have been generated that carry a CD45 minigene under control of the human leukocyte function-associated antigen (LFA-1, CD11a) promoter. CD45-null mice carrying the transgene exhibit the lymphocyte lineage-specific isoform expression patterns of wild-type mice. Furthermore, these mice have normal thymocyte development and peripheral T-cell(More)
Petunia protoplasts were infected with the virulent Agrobacterium tumefaciens strain A348 or the avirulent strain A136 (lacking a Ti plasmid). The infection process was stopped at various time intervals up to 24 h after inoculation, and the DNA from the plant cells was isolated. Southern blot analysis indicated that the DNA isolated from infected Petunia(More)
Consistent expression from CD45 cDNA constructs has proven difficult to achieve. Through the use of new CD45 cDNA constructs and reporter genes, the role 5', 3', and intron sequences play in CD45 expression was determined. The CD45 polyadenylation signal sequence was fully functional in a beta-galactosidase reporter construct. Furthermore, the CD45(More)
During adult life, the thymus involutes and thymic output of mature T cells drastically declines. The molecular events underlying this process are not well understood. Here, we present evidence of the importance of miRNAs in regulating T cell differentiation in the aged. miRNAs are a wide-ranging regulatory element influencing gene expression throughout the(More)