Applied Biosystems

About: Applied Biosystems is a based out in . It is known for research contribution in the topics: Mass spectrometry & Nucleic acid. The organization has 1521 authors who have published 1579 publications receiving 285423 citations.

Inhibition of activated pericentromeric SINE/Alu repeat transcription in senescent human adult stem cells reinstates self-renewal

Abstract: Cellular aging is linked to deficiencies in efficient repair of DNA double strand breaks and authentic genome maintenance at the chromatin level. Aging poses a significant threat to adult stem cell function by triggering persistent DNA damage and ultimately cellular senescence. Senescence is often considered to be an irreversible process. Moreover, critical genomic regions engaged in persistent DNA damage accumulation are unknown. Here we report that 65% of naturally occurring repairable DNA damage in self-renewing adult stem cells occurs within transposable elements. Upregulation of Alu retrotransposon transcription upon ex vivo aging causes nuclear cytotoxicity associated with the formation of persistent DNA damage foci and loss of efficient DNA repair in pericentric chromatin. This occurs due to a failure to recruit of condensin I and cohesin complexes. Our results demonstrate that the cytotoxicity of induced Alu repeats is functionally relevant for the human adult stem cell aging. Stable suppression of Alu transcription can reverse the senescent phenotype, reinstating the cells' self-renewing properties and increasing their plasticity by altering so-called "master" pluripotency regulators.

Detection and Quantitation of Human Papillomavirus by Using the Fluorescent 5′ Exonuclease Assay

Abstract: A method for the detection and quantitation of oncogenic human papillomavirus (HPV) was developed by using the fluorescent 5′ exonuclease assay. The method is based on the amplification of a 180-bp fragment from the 3′ part of the E1 open reading frame in a single PCR with type-specific probes for HPV types 16, 18, 31, 33, and 35. The probes can be used separately or in combinations of up to three probes per assay. Quantitation over a range of 101 to 106 initial HPV copies was possible by using real-time detection of the accumulation of fluorescence with cycle number. Reconstitution experiments, performed to mimic mixed infections, showed that individual HPV types can be detected down to a ratio of about 1% in a mixture. The performance of the assay depends on DNA quality, the presence of PCR inhibitors, and the number of different probes used simultaneously. This homogeneous assay provides a fast and sensitive way of screening for oncogenic HPV types in biopsy specimens as well as cervical smear samples. The closed-tube nature of the assay and the inclusion of uracil N′-glycosylase reduces cross contamination of PCR products to a minimum. A similar assay for β-actin was used in parallel for quantitation of genomic DNA. After normalizing the samples for genomic DNA content, the mean number of HPV copies per cell could be calculated.

Methods, kits and compositions pertaining to linear beacons

Abstract: This invention is directed to methods, kits and compositions pertaining to Linear Beacons. In the absence of a target sequence, Linear Beacons facilitate efficient energy transfer between the donor and acceptor moieties linked to opposite ends of the probe. Upon hybridization of the probe to a target sequence, there is a measurable change in at least one property of at least one donor or acceptor moiety of the probe which can be used to detect, identify or quantitate the target sequence in a sample.

Variation in the holm oak leaf proteome at different plant developmental stages, between provenances and in response to drought stress.

Abstract: Major proteins of the holm oak leaf proteome have been previously identified using a combination of 2-DE, MS analysis and BLAST similarity search (Jorge et al., Proteomics 2005, 5, 222-234). That study, conducted with field samples from mature trees, revealed the existence of a great variability in the 2-DE protein map, with qualitative as well as quantitative changes, both analytical and biological. A similar study has been carried out with 2-year-old seedlings to analyze and study: (i) changes in the 2-DE protein profile at different tree developmental stages; (ii) the 2-DE protein map variability between three different Spanish provenances; and (iii) variations in the 2-DE protein profile in response to drought stress. Although the protein profile of leaves from seedlings and mature trees was fairly similar, the biological variance found was lower in the former. In the present study, new proteins have been identified. At least four different protein spots differentiated Spanish provenances, two of them identified as an ATP synthase alpha chain, and a 2,3-bisphosphoglycerate-independent phosphoglycerate mutase. Fourteen different protein spots were qualitatively variable between well-watered and drought-stressed seedlings, with some of them corresponding to enzymes of carbohydrate and protein metabolism. Data presented indicated the mobilization of storage proteins and carbohydrates, as well as photosynthesis inhibition under drought conditions.

Essential role for Argonaute2 protein in mouse oogenesis.

Abstract: Argonaute2 protein (Ago2) is a key component of RNA-induced gene silencing complex, which is crucial for microRNA-mediated repression of target genes The function of Ago2 in the mouse oocyte and early embryonic development is less well characterized but it is likely to have an important role in regulating maternally inherited mRNA We have examined the role of Ago2 by conditional deletion of the gene in developing oocytes Ago2 was deleted specifically in the growing oocytes Although the Ago2-deficient oocytes are able to develop to mature oocytes, they have abnormal spindles and chromosomes that are unable to cluster together properly This phenotype is very similar to the phenotype of Dicer-deficient oocytes We examined the microRNA expression profile in the Ago2-deficient oocyte and found that the expression of most microRNAs was reduced by more than 80% To determine the downstream genes that are regulated by Ago2, we used microarray analysis on Ago2-deficient oocytes and found that 512 genes were upregulated and 1,073 genes were downregulated (FC > 2, P < 005) Our study shows that Ago2 has a key function in the mouse oocyte through global regulation of microRNA stability, and through this mechanism it affects gene expression in developing oocytes