Selected Low Noise Detectors      In addition to optimised optical paths selected high quality detectors are key to excellent sensitivity. The photomultiplier tubes (PMTs) used in the Mithras multimode readers are operated in the state-of-the-art ultra-fast single photon counting mode. Stringent selection along narrow limits for lowest background and highest efficiency ensures reliable and superior performance throughout all instruments.      For very demanding applications the photomultiplier tubes can be equipped with a Peltier-type cooling unit reducing the noise even further. Extended wavelength range type PMTs are available for near-infrared (NIR) fluorophores commonly used in fluorescence and timeresolved fluorescence energy transfer methods.      Dedicated Optical Path System (DOPS)      The Mithras operates with a dedicated optical path system (DOPS): for each reading technology there is an optimum optical system guaranteeing high sensitivity and wide dynamic range for all measurements. The path selection is done automatically by the instrument based on the user-selected reading parameters. Even multiple measurement technologies may be selected within a run. Detection Limits of less than 6 attomol ATP in luminescence mode and less than 2 attomol Europium in time-resolved fluorescence mode are impressive examples for the outstanding performance.      Filters – the better choice for most applications      The Mithras LB 940 is a filter-based system to extract the greatest benefits from the Dedicated Optical Path System (DOPS) as only filters with high transmission characteristics ensure best sensitivity. BRET and other colour luminescence applications are only possible with an extremely efficient optical system together with appropriate filters as used in the Mithras readers. Especially when little emission light is present as in fluorescence polarization and time-resolved fluorescence measurements the readings can be performed with higher sensitivity and better reproducibility using appropriate filters.      On top of that fluorescence ratio kinetic measurements – a popular approach for receptor and ion channel monitoring – need fast wavelength switching only filter-based systems can provide. The Mithras microplate readers can work with up to 20 excitation and more than 30 emission filters fulfilling the needs of any user group.      Plate Stacker      Unattended operation and increased throughput are facilitated with the Stacker unit LB 931. The stacker unit can simply be attached to the Mithras without any modifications of the main instrument. Two different types of stacks are available to hold either 25 or 50 microplates. They are easily exchangeable to match everday´s varying throughput needs. The stacker accepts 24, 96, 384 and 1536 well microplates from all major plate manufacturers.      Manual and robotic loading is still possible even with the stacker attached by simply removing the plate stacks. A unique feature of the LB 931 Stacker is the re-stacking operation mode which can be used in long-term kinetic monitoring of samples in multiple microplates, e.g. circadian rhythms of gene expression. Barcode readers may be added and used for positive plate identification or for automatically selecting parameter files containing the respective measurement settings. The software supports multiple options   for data storage using the barcode information.      Robot Integration      Specially designed for but not restricted to the use in HTS departments of drug discovery companies the robot access module allows for uncomplicated integration of the Mithras into any type of lab automation system. Software and hardware easily integrate into existing robotic or liquid handling systems.      BUTLER Plate Handler      With the BUTLER LB 930 another dimension of automation is revealed. A total capacity of up to 100 microplates can be handled. Any type of microplate can be loaded to the removable stacks.      Besides the Mithras plate reader additional devices for plate washing, pipetting or incubation may be added. It enables the setup of a complete workstation for assay preparation and measurement.      Throughput is optimized by the integration of the unique High Throughput Transfer & Loading (HTTL) station. It minimises the time loss while transferring measured microplates back to the stacks. A barcode reader is available for positive plate identification. The barcodes of the microplates can be stored with the measurement data. The BUTLER comes with a pre-configured setup and layout but can be individually configured at any time by the users.      Microplate Formats      Any kind of microplate regardless of its colour and design can be measured in Mithras. All microplate formats from 6 wells up to 1536 well can be measured when the automatic plate height adjustment option is present. In addition Petri dishes, Terasaki plates and filter membranes can be loaded with respective adapters. There is no need for any mechanical adjustment by the user – simply select the appropriate plate format in the operating software. The plate height adjustment module detects the height of the plate loaded and automatically adjusts the measurement optics for it.      Excitation & Emission Filters      Mithras microplate readers can work with up to 20 excitation and more than 30 emission filters conveniently mounted in exchangeable slides and wheels. These filter carriers are software-driven and provide quick change of emission and excitation filters within one run especially important for all applications with ratiometric readout, e.g. Indo-1, Fura 2 or BRET. The changing time for adjacent filter positions is as low as 130 ms made for highest resolution in kinetics. The filters offered by Berthold Technologies are high quality filters with selected transmission and bandwidth specifications for the respective applications. Additional filters can by added by the users at any time. Only filters with high transmission characteristics ensure best sensitivity needed for BRET and other colour luminescence assays. When little emission light is present as in fluorescence polarization and time-resolved fluorescence measurements the readings can be performed with higher sensitivity and better reproducibility using appropriate filters.      Microplate Shaking      The integral shaking function with 3 shaking modes – linear, orbital and double orbital – each of them adjustable in amplitude and speed can be activated to enhance mixing and optimise sample distribution before measurement. This can be very useful in long-term kinetic assays with cells.      Small footprint      Mithras LB 940 has been designed with a very small footprint. Housing dimensions are only 472 mm x 494 mm including reagent injectors saving valuable laboratory space.      Temperature Control      The Mithras can be equipped with a heating system for the microplates for assays which need to be measured at elevated and constant temperatures, e.g. common in cells based assays. Each parameter file can have its individual temperature setting which is simply activated by loading the respective parameter file. The detector is cooled by a Peltier unit to keep its temperature and noise low and maintain its high sensitivity.      Kinetics      With the Kinetic and Repeated measurement modes time courses of physiological processes can be monitored over short (few seconds) and long periods of time, e.g. up to 7 days. Enzyme activities, phagocytosis and Calcium monitoring are typical applications for the use of the kinetic functionality. The Kinetic and Repeated modes include possibilities to define interval and cycle times as well as intermittent injections or dual label settings (as in BRET and Fura 2 assays).      Flexible graphical displays and numerous calculation options enable sophisticated data evaluation, e.g. AUC, Vmax, slope, minimum, maximum. In addition the kinetic mode can support the user to establish optimum assay conditions or to monitor the reaction time of luminescence or fluorescence assays and define appropriate measurement times.      Well Scanning      The Scanning mode enables the researcher to scan a well of a microplate in up to 10,000 steps each of them creating an individual data point. This procedure is recommended when the assay is based on adherent cells which are heterogeneously distributed and signals are not located at the centers of the wells. A graphical representation of the signal distribution as well as mathematical formula for minimum, maximum, average and total signal facilitate data interpretion e.g. in chemotaxis applications.      Reagent Injectors      Up to 4 independently controlled injectors with variable volume give entire freedom in the selection of assay type and assay sequence. The injectors are located in measurement and pre-measurement positions of the luminescence and the fluorescence path respectively. JET injection technology stands for precision and accuracy - better than 98 %-and the most reliable way of proper mixing of the added reagents.      Tuneable injection speed covers the different demands of viscosities, cells or filling heights. The volumes are adjustable from 10to100µL–in increments of 1 µL. This is perfectly matching the requirements for reagent addition into 96 and 384 well plates. Dispensing can even be performed within a running kinetic measurement, e.g. to watch the effects of added agonists / antagonists. Cell-friendly materials and diameters as well as the ability for low speed injection make the Berthold Technologies JET injectors the ideal tools for the addition of cell suspensions to compound plates, e.g. in Aequorin-type Calcium assays. “Economy Prime” a special priming mode which is unique to Berthold Technologies JET injectors has been developed and implemented to facilitate homogeneous filling of the injection lines whilst using as little prime volume as possible helping the users to save valuable reagents.      Red enhanced photomultiplier      The red enhanced photomultiplier with an extended spectral range (340 – 800 nm) is especially designed for measurement of fluorescence dyes with emission wavelengths higher than 650 nm. The photomultiplier is Peltier cooled to reduce background noise.      Applications  

  
• Calcium monitoring  
• ATP determination  
• DNA probe assays  
• Fluorescence Resonance Energy Transfer (FRET)  
• Reporter gene assays  
• Homogeneous Functional GPCR Assay Using BRET Detection  
• Luminescent Immunoassays (LIA, ILMA)  
• HTRF® Kinase Assays  
• AlphaScreen™ Technology for Secondary Messenger Screening  
• Receptor-Ligand Binding Assays Based on Fluorescence Polarisation  
• Caspase Assays  
• SNPs