Polara g2 microscope

Manufactured by Thermo Fisher Scientific

The Polara G2 microscope is a high-performance electron microscope designed for advanced imaging and analysis of a wide range of samples. It features a state-of-the-art electron optical system, robust mechanics, and a user-friendly interface, providing researchers with a powerful tool for their scientific investigations.

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Lab products found in correlation

Falcon 3 direct electron detector, by Thermo Fisher Scientific (2 mentions) Cryoplunge 3, by Ametek (2 mentions) Falcon 2 detector, by Thermo Fisher Scientific (1 mentions) Falcon 2, by Thermo Fisher Scientific (1 mentions) Falcon 3, by Thermo Fisher Scientific (1 mentions)

Close spelling variants of this product

Polara G2 electron microscope (18 citations) Polara (11 citations) Polara microscope (7 citations) Tecnai G2 Polara microscope (7 citations) Tecnai G2 Polara transmission electron microscope (6 citations) G2 Polara (3 citations)

6 protocols using polara g2 microscope

Cryo-EM Imaging of RelA Complex

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Aliquots of 3 μl of the RelA complex were incubated for 20 s on glow-discharged holey carbon grids (Quantifoil R2/2), on which a ~30 Å thick home-made amorphous carbon film had previously been deposited. The grids were blotted for 5 s in 100 % humidity at 4 °C before being flash cooled in liquid ethane using a Vitrobot MKII (FEI).
Grids were transferred to a Polara G2 microscope (FEI) operated at 300 kV. Images were recorded with the EPU automated data acquisition software on a Falcon III direct electron detector (FEI) at a calibrated magnification of 104,478 (yielding a pixel size of 1.34 Å). Images were collected with a total dose of 35 e^-/Å² and a defocus range of -1.8 to -3.0 μm. A bespoke system was used to intercept the videos from the detector at a speed of 30 frames for the 1.1 s exposures.

Brown A., Fernández I.S., Gordiyenko Y, & Ramakrishnan V. (2016). Ribosome-dependent activation of stringent control. Nature, 534(7606), 277-280.

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Cryo-EM Imaging of RelA Complex

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Brown A., Fernández I.S., Gordiyenko Y, & Ramakrishnan V. (2016). Ribosome-dependent activation of stringent control. Nature, 534(7606), 277-280.

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Electron Microscopy Sample Preparation

Cited 2 times

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The grids with sample for electron microscopy were prepared as described earlier (Fernández et al., 2014 (link)). Data acquisition was done on an FEI Polara G2 microscope operated at 300 kV under low-dose conditions (28 e⁻/Å²) using a defocus range of 1.6–4.0 μm. Images were recorded manually on a back-thinned FEI Falcon II detector at calibrated magnification of 104,478 (yielding a pixel size of 1.34 Å). An in-house system was used to intercept the videos from the detector at a speed of 16 frames/s exposures, as described earlier (Bai et al., 2013 (link)). Micrographs that showed noticeable signs of astigmatism or drift were discarded.

Hussain T., Llácer J.L., Fernández I.S., Munoz A., Martin-Marcos P., Savva C.G., Lorsch J.R., Hinnebusch A.G, & Ramakrishnan V. (2014). Structural Changes Enable Start Codon Recognition by the Eukaryotic Translation Initiation Complex. Cell, 159(3), 597-607.

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HPV Capsid Fab Complex Cryo-EM Imaging

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HPV16 was incubated with an excess of 4 Fab molecules for each of the predicted 360 binding sites per capsid for 1 h at room temperature and concentrated to 1.2 mg/mL in PBS buffer. A volume of 3 µL of virus-Fab complex was applied to Quantifoil holey carbon support grids (Quantifoil, Jena, Germany), blotted and plunged into liquid ethane using a Cryoplunge 3 (Gatan, Pleasanton, CA, USA). Low-dose micrographs were recorded using an FEI Polara G2 microscope operating at 300 kV. Images were collected under the control of the E Pluribus Unum software program (EPU) using an FEI Falcon 2 direct electron detector with 1.4× post-column magnification and a nominal magnifications of 59,000× for HPV-V5 and 93,000× for HPV-U4, yielding calibrated pixel sizes at the sample of 1.75 Å and 1.15 Å, respectively. Defocus ranges of 0.65–3.56 µm and 0.26–5.18 µm (Table 1) were measured for micrographs of HPV-V5 and HPV-U4, respectively. REgularized LIkelihood OptimizatioN (RELION), AUTO3DEM and Electron Micrograph ANaly-sis (EMAN2) program software suites were used for image processing and 3D reconstructions [46 (link),47 (link),48 (link)].

Guan J., Bywaters S.M., Brendle S.A., Ashley R.E., Makhov A.M., Conway J.F., Christensen N.D, & Hafenstein S. (2017). High-Resolution Structure Analysis of Antibody V5 and U4 Conformational Epitopes on Human Papillomavirus 16. Viruses, 9(12), 374.

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Cryo-EM Imaging of 80S Initiation Complex

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The 80S initiation complex was diluted to ∼80 nM, and 3 μL were spotted on glow-discharged holey carbon grids (Quantifoil R2/2) deposited with a homemade continuous thin carbon film (estimated to be ∼30 Å thick) for 30 s. Each grid was blotted for 2.5 s and flash-frozen in liquid ethane using an FEI Vitrobot. The grids were imaged with an FEI Polara G2 microscope operating at 300 kV. Defocus values in the final dataset ranged from 1.6 to 3.6 µm. Images were recorded manually on a back-thinned FEI Falcon III detector at a pixel size of 1.07 Å in linear mode. The individual frames from the detector (36 frames for each 1-s exposure) were captured and stored on disk. All electron micrographs were evaluated for astigmatism and drift.

Huang B.Y, & Fernández I.S. (2020). Long-range interdomain communications in eIF5B regulate GTP hydrolysis and translation initiation. Proceedings of the National Academy of Sciences of the United States of America, 117(3), 1429-1437.

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Structural Characterization of HPV-Heparin Binding

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HPV16 was incubated with a 5-fold excess of heparin molecules (Sigma-Aldrich, catalog no. H1027) according to an average mass of 16 kDa per molecule and 360 binding sites predicted per capsid. HPV-heparin was incubated for 1 hr at 37 C and concentrated to 0.8 mg/mL in PBS buffer. An aliquot of 3 mL of virus-Fab complex was vitrified on QUANTIFOIL R2/1 holey carbon support grids (Quantifoil) that were vitrified by plunge-freezing into liquid ethane using a Cryoplunge 3 (Gatan). Low-dose micrographs were recorded using an FEI Polara G2 microscope operating at 300 kV. Images were collected under the software control of the EPU program using an FEI Falcon 2 direct electron detector with a nominal magnification of 93,0003 yielding a calibrated pixel size at the sample of 1.15 A ˚. A similar procedure was followed to prepare and collect data for untreated HPV particles. Defocus ranges of 1.04-5.19 and 0.78-4.85 mm (Table 1) were measured respectively for micrographs of HPV16 and HPV16-heparin, respectively. RELION, AUTO3DEM, and EMAN2 program suites were used for image processing and 3D reconstructions (Scheres, 2012; Tang et al., 2007; Yan et al., 2007) .

Guan J., Bywaters S.M., Brendle S.A., Ashley R.E., Makhov A.M., Conway J.F., Christensen N.D, & Hafenstein S. (2017). Cryoelectron Microscopy Maps of Human Papillomavirus 16 Reveal L2 Densities and Heparin Binding Site. Structure (London, England : 1993), 25(2).

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