SDS 1.9.1

Macintosh G3

OS 9

Informal Description

The 7700 Does the same thing as the 9700 just slightly slower.  It uses a real laser (Golly Gee Whiz Batman!) so it is more accurate and versatile than halogen based systems like the 7500, 7300 and Strategenes MX systems.  The cycler is a modified 9600 which is easy to maintain, replace or repair now that there are so many spare parts available.  The two major drawbacks are size (about 1 bench with the MAC) and that you are stuck with MAC OS9.  There is no way to upgrade or convert to PC.  Other than that it is THE classic RT-PCR instrument and can be a good work horse for labs with small budgets.

Formal (somewhat antiquated) Description
The ABI 7700 Quantitative PCR Robot is a Real-Time PCR instrument that allows one to quantify PCR reactions as they happen. The ABI PRISM 7700 Sequence Detection System is a fully integrated system for real-time detection of PCR. The system includes a built-in thermal cycler, a laser to induce fluorescence, CCD (charge-coupled device) detector, real-time sequence detection software, and TaqMan® reagents for the fluorogenic 5' nuclease assay.

The ABI 7700 incorporates sequence specific primers specially designed with an end labeled fluorescent dye. These dye primers are used in addition to standard unlabeled sequence initiation primers. During the annealing phase of PCR, the labeled primer anneals to the fragment at its complementary site. In the extension phase the labeled primer is removed by polymerase, which also causes the primer to fluoresce. This fluorescence is then detected by a laser specific to each and every well in the reaction plate. The ABI 7700 system uses standard PCR in conjunction with a fluorogenic probe in which the intensity of fluorescence is proportional to the amount of target DNA present.

Applications
Some applications of real-time PCR using the 7700 system are: Allelic Discrimination, SR Plates, PlusMinus Scoring, and IPC's. Applications: real-time quantitation, allele detection, pathogen detection research

Specifications
Using the TaqMan® RNase P Instrument Verification Plate and protocol provided in the install kit, the 7700 Sequence Detector distinguishes between 5,000 and 10,000 replicate populations with 99.7% confidence level

Run Time
The run time for the 7700 is typical of most thermocyclers (about 2.5 hours) and can be adjusted depending on need.

Condition
Reconditioned to ABI service contract requirements and can be put directly under service contract.

Feature Highlights 
Precision optics provides highly reproducible and quantitative results

Large dynamic range eliminates the need to make serial dilutions of unknown samples

Closed-tube detection reduces the risk of sample contamination and eliminates the use of electrophoresis

Multiple chemistries enable versatile assay development.

The basis for PCR quantitation in the ABI 7700 instrument is to continuously measure PCR product accumulation using a dual-labeled flourogenic oligonucleotide probe called a TaqMan® probe. This probe is composed of a short (ca. 20-25 bases) oligodeoxynucleotide that is labeled with two different flourescent dyes. On the 5' terminus is a reporter dye and on the 3' terminus is a quenching dye. This oligonucleotide probe sequence is homologous to an internal target sequence present in the PCR amplicon. When the probe is intact, energy transfer occurs between the two flourophors and emission from the reporter is quenched by the quencher. During the extention phase of PCR, the probe is cleaved by 5' nuclease activity of Taq polymerase thereby releasing the reporter from the oligonucleotide-quencher and producing an increase in reporter emission intensity. The ABI Prism 7700 uses fiber optic systems which connect to each well in a 96-well PCR tray format . The laser light source excites each well and a CCD camera measures the fluorescence spectrum and intensity from each well to generate real-time data during PCR amplification. The ABI 7700 Prism software examines the fluorescence intensity of reporter and quencher dyes and calculates the increase in normalized reporter emission intensity over the course of the amplification. The results are then plotted versus time, represented by cycle number, to produce a continuous measure of PCR amplification. To provide precise quantification of initial target in each PCR reaction, the amplification plot is examined at a point during the early log phase of product accumulation. This is accomplished by assigning a fluorescence threshold above background and determining the time point at which each sample's amplification plot reaches the threshold (defined as the threshold cycle number or CT). Differences in threshold cycle number are used to quantify the relative amount of PCR target contained within each tube as described previously.

Practice of the patented polymerase chain reaction (PCR) process requires a license. The ABI PRISM® 7700 Sequence Detection System is an Authorized Thermal Cycler for PCR and may be used with PCR licenses available from Applied Biosystems. Its use with Authorized Reagents also provides a limited PCR license in accordance with the label rights accompanying such reagents. Purchase of this instrument does not convey any right to practice the 5' nuclease assay or any of the other real-time methods covered by patents owned by Roche or Applied Biosystems. The PCR process and 5' nuclease process are covered by patents owned by Roche Molecular Systems, Inc. and F. Hoffmann-La Roche Ltd

Quantitative PCR with no gel? Impossible! Now with the ABI PRISM 7700 Sequence Detection System, real time PCR has become a reality. Combining a novel chemistry with a fully integrated PCR amplification and detection system, the 7700 System is a unique, closed-tube system that allows for real time quantitative PCR without sample processing or electrophoresis.

At the core of the system is a 5' nuclease assay conducted with the TaqMan¨ PCR Reagent Kit utilizing a fluorogenic probe that has both a reporter and quencher dye attached. When both dyes are attached to the probe, reporter dye emission is quenched. However, once annealed to the target sequence and put into a PCR reaction, the nuclease activity of the Taq polymerase cleaves the reporter dye from the probe, resulting in a fluorescent signal. The fluorescent signal is monitored at every cycle as additional reporter dye molecules accumulate.

Real time PCR offers numerous advantages over previous attempts at quantitating PCR. Other methods typically rely on end-point measurements, when often the reaction has gone beyond the exponential phase because of limiting reagents. To compensate for such problems, competitive PCR was devised, which allows for normalization of the end product based on the ratio between target and competitor. Because this method is cumbersome, requiring a carefully constructed competitor target for each PCR reaction and a series of dilutions to ensure that there is a suitable ratio of target to competitor, it is seldom used successfully. In contrast, with real time PCR, the dynamic range is much greater than that of competitive PCR (over six orders of magnitude as compared to one with competitive PCR), post-reaction processing is eliminated, and the measurements are taken from the exponential range of the reaction, where component concentrations are not limiting. And best of all, the entire process is automated.

The ABI 7700 Sequence Detection System includes a built-in thermal cycler, a fluorogenic 5' nuclease assay, a laser for inducing fluorescence, charge-coupled device (CCD) detection, and PCR application software. The specially designed reaction tube with transparent lid allows light from a laser, carried on fiber optic cables, to excite the probe and allows the emitted light to be sent back to a CCD camera for detection without the user ever having to open the tube. Being a closed tube system all the way through to the detection phase eliminates the possibility of contamination and the necessity for special procedures and rooms. Designed for high- throughput applications, the 7700 System collects fluorescent emission between 500 and 660 nm in each of 96 sample wells every few seconds and displays results in one minute after the reaction is completed.

While not inexpensive, costing in the vicinity of $95,000, to some users, the savings in labor and in the expense of processing samples has actually made PCR more affordable. Of the ABI PRISM 7700, Mickey Williams of Genetech said, "In the past, PCR was simply too costly and time-consuming to be used as a routine test . . ." "A project that used to take weeks can now be completed in a matter of days." Charlotte Ip, Senior Research Fellow at Merck, said of the 7700 System,"After using other types of quantitative PCR methods, this system is by far the best. It has many applications and performs very well [both with respect to] quantitation and accuracy."

The PRISM 7700 system is able to analyze up to 500 samples a day, vastly more than any other kind of PCR analysis. With this system, time required to screen drugs for effects on gene expression should be significantly accelerated. A single computer with a graphical user interface controls not only data analysis but also set-up of PCR conditions, allowing fast and convenient programming of PCR reactions.