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.

Suppression of alpha-cyano-4-hydroxycinnamic acid matrix clusters and reduction of chemical noise in MALDI-TOF mass spectrometry

Abstract: Progress in high-throughput MALDI-TOFMS analysis, especially in proteome applications, requires development of practical and efficient procedures for the preparation of proteins and peptides in a form suitable for high acquisition rates. These methods should improve successful identification of peptides, which depends on the signal intensity and the absence of interfering signals. Contamination of MALDI samples with alkali salts results in reduced MALDI peptide sensitivity and causes matrix cluster formation (widely reported for CHCA matrix) observed as signals dominating in the range below m/z 1200 in MALDI spectra. One way to remove these background signals, especially for concentrations of peptides lower than 10 fmol/microL, is to wash matrix/sample spots after peptide cocrystallization on the MALDI plate with deionized water prior to analysis. This method takes advantage of the low water solubility of the CHCA compared to its alkali salts. We report here that the application of some ammonium salt solutions, such as citrates and phosphates, instead of deionized water greatly improves the efficiency of this washing approach. Another way to reduce matrix cluster formation is to add ammonium salts as a part of the MALDI matrix. The best results were obtained with monoammonium phosphate, which successfully suppressed matrix clusters and improved sensitivity. Combining both of these approaches-the addition of ammonium salts in the CHCA matrix followed by one postcrystallization washing step with ammonium buffer-provided a substantial ( approximately 3-5-fold) improvement in the sensitivity of MALDI-MS detection compared to unwashed sample spots. This sample preparation method resulted in improved spectral quality and was essential for successful database searching for subnanomolar concentrations of protein digests.

Separation of 4-color DNA sequencing extension products in noncovalently coated capillaries using low viscosity polymer solutions.

Abstract: A low viscosity (ca. 75cP) solution using polydimethylacrylamide (PDMA) was developed for separating DNA sequencing extension products by capillary electrophoresis (CE). This medium gave a length-of-read (LOR) value of approximately 600 bases in about 2 h using four-color sequencing in 50 microm capillary at 42 degrees C under a field of 160 V/cm. This medium also works in bare capillaries by noncovalently coating the surface to suppress both electroosmotic flow (EOF) and DNA-capillary wall interactions, and eliminates the need for complicated covalent coatings. At least 100 successive sequencing runs were performed in the same capillary by simply pumping fresh medium after every run, without requiring any reconditioning of the capillary surface between runs. The thermal stability of the noncovalent coating can be improved by adding small amounts of high molecular weight PDMA to the separation medium. The advantages of low viscosity separation media and uncoated capillaries are of paramount importance to develop high-throughput instruments for DNA sequencing.

Radiation modulation of microRNA in prostate cancer cell lines.

Abstract: Background MicroRNAs (miRNA) are gene regulators and play an important role in response to cellular stress.

Development and validation of the AmpFlSTR MiniFiler PCR Amplification Kit: a MiniSTR multiplex for the analysis of degraded and/or PCR inhibited DNA.

Abstract: DNA typing of degraded DNA samples can be a challenging task when using the current commercially available multiplex short tandem repeat (STR) analysis kits. However, the ability to type degraded DNA specimens improves by redesigning current STR marker amplicons such that smaller sized polymerase chain reaction (PCR) products are generated. In an effort to increase the amount of information derived from these types of DNA samples, the AmpFlSTR MiniFiler PCR Amplification Kit has been developed. The kit contains reagents for the amplification of eight miniSTRs which are the largest sized loci in the AmpFlSTR Identifiler PCR Amplification Kit (D7S820, D13S317, D16S539, D21S11, D2S1338, D18S51, CSF1PO, and FGA). Five of these STR loci (D16S539, D21S11, D2S1338, D18S51, and FGA) also are some of the largest loci in the AmpFlSTR SGM Plus kit. This informative nine-locus multiplex, which includes the gender-identification locus Amelogenin, has been validated according to the FBI/National Standards and SWGDAM guidelines. Our results demonstrate significant performance improvements in models of DNA degradation, PCR inhibition, and nonprobative samples when compared to the AmpFlSTR Identifiler and SGM Plus kits. These data support that the MiniFiler kit will increase the likelihood of obtaining additional STR information from forensic samples in situations in which standard STR chemistries fail to produce complete profiles.