The Eppendorf Mastercycler Gradient is built around a single universal block that accommodates either 96-well plates, 96-0.2 ml PCR tubes or 77-0.5 ml PCR tubes. A distinguishing feature that sets it apart from competitors is the gradient range (spread over 20
oC). The remaining parameters – heated lid, user-selectable ramping rate of up to 3
o/s, programming capacity of 100 programs with up to 99 steps each, etc. are rather standard for all similar PCR instruments. Although other personal cyclers may be faster or present graphical information more clearly; the versatility of this instrument based on the gradient range is second to none. In addition, this system enables optimization of PCR reactions in a single step.
The system is best suited for labs that do a lot of exploratory PCR work, such as amplifying genomic DNA fragments or performing site-directed mutagenesis.
Programming of the instrument is adequate, but tedious, due to the small screen. The size of the screen imposes a major limitation on the operators and navigational tools that can be implemented in the software. Eppendorf engineers have attempted to solve the problem with an abundance of buttons on the front panel. There is a full numerical pad, 4-directional wheel, buttons for Start/Stop and Enter/Exit, as well as 4 somewhat less intuitive ones such as Sel(ect) or Ins(ert) (for example, Sel is used to scroll through alphabet during typing). The learning curve for the instrument is not steep, but a new user will be turning to the manual more often than would be the case with similar models from BioRad or Thermo to look up some of the more obscure button functions.
The temperature ramping rate in this cycler is also adequate, although not exceptional. In side-by-side testing, Mastercycler performed simple amplification on par with Takara Dice and Bio-Rad iCycler, trailing behind Thermo PX2. During long primer extension reactions – such as QuickChange site-directed mutagenesis – the differences became quite negligible, as ramping rate ceased to be a limiting factor.
We have used MasterCycler Gradients both in research and teaching labs, where these instruments have proven to be reliable tools for generating in vitro transcription templates, PCR screening of colonies, performing random and site-directed mutagenesis and amplifying segments of genomic DNA for subcloning into expression vectors (including high-GC genes from extremophiles). The heated lid positions are designed to fit Eppendorf’s own tubes only, thus PCR tubes from other manufacturers have to be checked for compatibility prior to use (we used both Eppendorf and CLP Direct tubes with similar results). Optional memory cards that store up to 10 individual programs work well, but are not very popular due to small capacity. Operation of the MasterCycler Gradient is rather quiet and does not negatively impact noise level in the lab.
Vladimir Svetlov PhD
Dept. Microbiology
Ohio State University