Objective: To develop a new nonisotopic detection method of enzyme-amplified time-resolved fluorescence (EATRF) or enzyme-amplified lanthanide luminescence (EALL) for nucleic acid hybridization assays, which can be applied extensively in clinical diagnosis.
Methods: The method combines the high affinity of biotin-streptavidin system, amplification of enzyme, and inherent advantage of lanthanide chelate with the background elimination of time-resolved fluorescence detection. The conversion of 5-fluorosalicyl phosphate to 5-fluorosalicylic acid (5-FSA) by alkaline phosphatase. The salicylic acid product forms a luminescent ternary chelate with Tb3+ and EDTA.
Results: The dynamic range of the standard curve of EATRFA for nucleic acid hybridization assay was very wide, the range was more than third order of magnitude. The detection sensitivity was about 10 pg of target sequence. When the known target sequence was 20, 10 and 2 ng, the ratio of measured amount to known amount was 110%, 90% and 115% respectively. The main experimental conditions, for example, the irradiating time of ultraviolet rays, the concentrations of biotinylated probe, AP-SA, 5-FSAP and Tb-EDTA and the methods of washing in the related steps, have been optimized. A new stable technology of fluorescence has been developted.
Conclusions: EATRF detection for nucleic acid hybridization assays is a new sensitive simple method, which has a great prospect.
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Proc Natl Acad Sci U S A
January 2025
Department of Biology, Indiana University, Bloomington, IN 47405.
Transgenic expression of a double-stranded RNA in plants can induce silencing of homologous mRNAs in fungal pathogens. Although such host-induced gene silencing is well documented, the molecular mechanisms by which RNAs can move from the cytoplasm of plant cells across the plasma membrane of both the host cell and fungal cell are poorly understood. Indirect evidence suggests that this RNA transfer may occur at a very early stage of the infection process, prior to breach of the host cell wall, suggesting that silencing RNAs might be secreted onto leaf surfaces.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Department of Chemistry and Biochemistry, The University of Texas at Dallas, Richardson, TX 75080.
The TRAMP complex contains two enzymatic activities essential for RNA processing upstream of the nuclear exosome. Within TRAMP, RNA is 3' polyadenylated by a subcomplex of Trf4/5 and Air1/2 and unwound 3' to 5' by Mtr4, a DExH helicase. The molecular mechanisms of TRAMP assembly and RNA shuffling between the two TRAMP catalytic sites are poorly understood.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Center for Mitochondrial and Epigenomic Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104.
Mitochondrial DNA (mtDNA) is highly polymorphic, and host mtDNA variation has been associated with altered cancer severity. To determine the basis of this mtDNA-cancer association, we analyzed conplastic mice with the C57BL/6J (B6) nucleus but two naturally occurring mtDNA lineages, and , where mitochondria generate more oxidative phosphorylation (OXPHOS)-derived reactive oxygen species (mROS). In a cardiac transplant model, Foxp3+ T regulatory (Treg) cells supported long-term allograft survival, whereas Treg cells failed to suppress host T effector (Teff) cells, leading to acute rejection.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Laboratory of Obesity and Aging Research, Cardiovascular Branch, National Heart Lung and Blood Institute, NIH, Bethesda, MD 20892.
Mitochondrial endonuclease G (EndoG) contributes to chromosomal degradation when it is released from mitochondria during apoptosis. It is presumed to also have a mitochondrial function because EndoG deficiency causes mitochondrial dysfunction. However, the mechanism by which EndoG regulates mitochondrial function is not known.
View Article and Find Full Text PDFSci Adv
January 2025
Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, Louisiana Cancer Research Center, 1700 Tulane Avenue, New Orleans, LA 70112, USA.
Unlike most species that use telomerase for telomere maintenance, many dipterans, including , rely on three telomere-specific retrotransposons (TRs)-, , and -to form tandem repeats at chromosome ends. Although TR transcription is crucial in their life cycle, its regulation remains poorly understood. This study identifies the Mediator complex, E2F1-Dp, and Scalloped/dTEAD as key regulators of TR transcription.
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