New Study Shows Embryonic Stem Cell Lines Classified by ``MicroRNA'' Expression; Applied Biosystems TaqMan MicroRNA Assays Quantify Minute Changes in MicroRNA Expression during Stem Cell Differentiation.

SAN FRANCISCO -- Results May Have Implications in Determining Optimal Stem Cell Lines for Therapeutic Research

In conjunction with the International Society for Stem Cell Research (ISSCR) Annual Meeting, Applied Biosystems Group (NYSE:ABI), an Applera Corporation business, and the University of Colorado today presented data using a preliminary version of Applied Biosystems TaqMan(R) MicroRNA Assays to profile microRNA (miRNA) expression in mouse stem cells.

The collaborative research study shows embryonic stem cells can be classified according to miRNA expression profiles, potentially having implications in determining optimal stem cell lines. Using TaqMan miRNA assays, researchers were able to accurately determine expression levels across a large panel of miRNAs and reveal precise changes in individual miRNA expression during stem cell differentiation. The assays discriminated between miRNAs differing by as little as a single nucleotide and between mature miRNAs and their precursors, even in single cells.

Increasing evidence indicates miRNAs, a recently discovered class of small RNA molecules, play a powerful gene regulatory role in cell differentiation and developmental biology, cancer, and other diseases.

"The different microRNA expression profiles in embryonic stem cells suggest some embryonic cell cultures may contain variable subpopulations of spontaneously differentiated cells," said William M. Strauss, Ph.D., Assistant Research Professor, Department of Molecular, Chemical and Developmental Biology (MCDB), University of Colorado, Boulder. "Our newly identified microRNAs could one day be used as molecular markers for monitoring differentiation within embryonic stem cell lines."

Researchers examined the expression levels of 252 mouse and human miRNAs in four mouse embryonic stem cell lines, differentiated embryoid bodies, and six mouse tissues. Preliminary results found embryonic stem cells could be accurately classified and differentiated from embryoid bodies and adult tissue using their distinct miRNA expression signatures.

"We are excited about the potential of our novel TaqMan(R) MicroRNA Assays to provide further insights about the role of miRNAs in cell differentiation," said Dennis Gilbert, Ph.D., Chief Scientific Officer, Applied Biosystems. "This is the first time a technology has been able to quantify miRNAs easily and accurately using starting samples as small as a single cell. These findings may hold promise for stem cell researchers as they identify optimal cell lines for use in therapeutic research."

In addition, data showed a total of 55 percent (138) of miRNAs studied were up-regulated by more than a fold, while only one percent (3) were down-regulated during the development of embryonic stem cells into embryoid bodies, suggesting miRNA expression levels globally increase during embryonic stem cell differentiation and may play an important role in activating lineage-specific genes.

Applied Biosystems TaqMan(R) MicroRNA Assays distinguish between mature miRNAs and their precursor form by using a proprietary stem-loop technology for reverse transcription (RT) of the mature miRNA, followed by quantitative real-time PCR. Applied Biosystems currently has a large set of the miRNA assays in development and plans to commercialize its miRNA assay technology based on TaqMan(R) 5' nuclease chemistry for real-time PCR.

The poster (#53), titled "TaqMan-Based MiRNA Profiles Classify Embryonic Stem Cells (ES) and Differentiated Cells," will be presented at ISSCR today, June 23, from 5:30 to 7 p.m. and during an ISSCR tutorial, titled "Real-Time PCR Applications for Stem Cell Research," from 7 to 8 p.m. To register for the tutorial go to http://info.appliedbiosystems.com/isscr. A copy of the poster can be downloaded at http://miRNA.appliedbiosystems.com.

About University of Colorado

The University of Colorado is a three-campus system with campuses in Boulder and Colorado Springs, and the recently consolidated Denver and Health Sciences Center campuses located in Denver and at the former Fitzsimons Army Base in Aurora. For further information, please contact Michele McKinney in the CU System Office of Institutional Relations at [phone].

About Applera Corporation and Applied Biosystems

Applera Corporation consists of two operating groups. The Applied Biosystems Group serves the life science industry and research community by developing and marketing instrument-based systems, consumables, software, and services. Customers use these tools to analyze nucleic acids (DNA and RNA), small molecules, and proteins to make scientific discoveries, develop new pharmaceuticals, and conduct standardized testing. Applied Biosystems is headquartered in Foster City, CA, and reported sales of $1.7 billion during fiscal 2004. The Celera Genomics Group (NYSE:CRA) is engaged principally in the discovery and development of targeted therapeutics for cancer, autoimmune and inflammatory diseases. Celera Genomics is leveraging its proteomic, bioinformatic, and genomic capabilities to identify and validate drug targets, and to discover and develop small molecule therapeutics. It is also seeking to advance therapeutic antibody and selected small molecule drug programs in collaboration with global technology and market leaders. Celera Diagnostics, a 50/50 joint venture between Applied Biosystems and Celera Genomics, is focused on discovery, development, and commercialization of diagnostic products. Information about Applera Corporation, including reports and other information filed by the company with the Securities and Exchange Commission, is available at http://www.applera.com, or by telephoning 800.762.6923. Information about Applied Biosystems is available at www.appliedbiosystems.com.

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For Research Use Only. Not for use in diagnostic procedures.

The PCR process and the 5' nuclease process are covered by patents owned by Roche Molecular Systems, Inc. and F. Hoffmann-La Roche Ltd.

Copyright(C) 2005. Applera Corporation. All rights reserved. Applied Biosystems and Celera are registered trademarks and Applera is a trademark of Applera Corporation or its subsidiaries in the U.S. and/or certain other countries. TaqMan is a registered trademark of Roche Molecular systems, Inc.