Variations On Microarray Technology

The microarray platform used can be defined by the following factors:

• Probes can be double-stranded DNA (usually several thousand bases), single-stranded oligonucleotide sequences 20-75 bases), antibodies, other proteins or biomolecules, chemical entities, and even tissue slices.

• Probes can be deposited robotically or by fluid mechanics; oligonucleotide sequences can also be

Biomolecule Extraction Robot Rm4004

Fig. 1 Typical workflow for a cDNA microarray experiment. This example is based on oligonucleotide gene probes on a custom spotted array, using dual-dye cohybridization of two different samples on each array. Based on a genome of interest, probes are selected and synthesized. Using a robot, one can then arrange these probes into a grid on the substrate (in this case, a glass slide), where they remain bound to the surface by electrostatic forces, covalent cross-linking, or other means of attachment. On the other side of the process, biological samples are obtained from tissues or cell lines, followed by the extraction of total RNA and reverse transcription to cDNA. The last step also includes the dye-labeling step, and the sample is now referred to as target sample. In this case, a target sample from a control or reference condition has been dye labeled with Cy5, a target sample from an experimental or test condition with Cy3. These samples are then mixed and cohybridized to one array. This is followed by scanning the array at frequencies corresponding to both dye labels. The resulting false-color images can be obtained separately or as a composite image. Probes appearing red are more abundant (or higher expressed) in the experiment sample, probes appearing green are more abundant in the reference sample, and probes appearing yellow are equally abundant in both samples. (View this art in color at www.dekker.com.)

Fig. 1 Typical workflow for a cDNA microarray experiment. This example is based on oligonucleotide gene probes on a custom spotted array, using dual-dye cohybridization of two different samples on each array. Based on a genome of interest, probes are selected and synthesized. Using a robot, one can then arrange these probes into a grid on the substrate (in this case, a glass slide), where they remain bound to the surface by electrostatic forces, covalent cross-linking, or other means of attachment. On the other side of the process, biological samples are obtained from tissues or cell lines, followed by the extraction of total RNA and reverse transcription to cDNA. The last step also includes the dye-labeling step, and the sample is now referred to as target sample. In this case, a target sample from a control or reference condition has been dye labeled with Cy5, a target sample from an experimental or test condition with Cy3. These samples are then mixed and cohybridized to one array. This is followed by scanning the array at frequencies corresponding to both dye labels. The resulting false-color images can be obtained separately or as a composite image. Probes appearing red are more abundant (or higher expressed) in the experiment sample, probes appearing green are more abundant in the reference sample, and probes appearing yellow are equally abundant in both samples. (View this art in color at www.dekker.com.)

assembled in situ (e.g., using lithography methods) on the array.

The most common protein/DNA array formats are glass slides (standard microscopy size) with various coatings or fully encapsulated cartridges containing the array.

For single-target arrays, one target sample is labeled and assayed against one array. For dual-target arrays, two target samples are differentially labeled and assayed against one array.

Labeling approaches include dyes, reflective or light-scattering particles, antibodies, or radioactive material.

level of laboratory protocols is therefore required. It has now frequently become a prerequisite for publication to record these steps at minimum information about a micro-array experiment (MIAME) level set by the Microarray Gene Expression Data society (http://www.mged.org).

Laboratory protocols should cover precise instructions for sample acquisition and processing, array production and processing, the selection and synthesis of probes, labeling steps, the hybridization process, posthybridiza-tion processes, and storage. It is highly recommended that rigorous standard operating procedures be applied for both benchwork and data capture.[3]

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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