Centrifugation microfuges

Neomycin phosphotransferase II (NPTII) extraction from cotton leaves and cottonseed. The extraction buffer consists of 100 mM Tris, lOmM sodium borate, 5mM magnesium chloride, 0.2% ascorbate and 0.05% Tween 20 at pH 7.8. The frozen leaf sample is homogenized in cold (4 °C) buffer. An aliquot of the homogenate is transferred to a microfuge tube and centrifuged at 12 000 g for 15 min. The supernatant is diluted and assayed directly by ELISA. 

If some precipitation occurs, clarify the solution by centrifugation using a microfuge. Remove excess reactant by gel filtration using a desalting resin. 

Analysis of the Copolymerizabilities of Monomers The composition of the copolymers formed was determined by measuring the relative amounts of each monomer, NIPAAM and AAM, that remained in solution after a copolymerization. Copolymerizations were terminated by addition of 1 ml of reaction mix to 9 ml of 0.1% phosphoric acid at 50 C, followed by centrifugation of a 0.4 ml aliquot at 6,500 x g for 5 minutes in an Eppendorf microfuge. After 100 fold dilution of an aliquot of the supernate, 200 pi of this was injected onto an IBM reversed phase Cig HPLC column pre-equilibrated with 2% acetonitrile in 0.1% aqueous phosphoric acid and the eluent monitored at 214 nm. The monomers were eluted using a 0.1% aqueous phosphoric acid (solvent A) acetonitrile (solvent B) gradient as follows for 5 minutes the solvent was 98% solvent A and 2% solvent B, followed by a linear gradient to 80% A and 20% B over 10 minutes. After 5 more minutes at 80% A and 20% B, the solvent was returned to 98% A and 2% B. 

Centrifuge the last traces of PVDF membrane from the combined supernatants in a microfuge at maximum revolutions for 5 min. 

Centrifuge at 2000-4000g for 15-20 min at 4°C (alternatively for small volumes of 1-5 mL, microfuge for 1-2 min). Discard the supernatant, and dram the pellet (carefully invert the tube over a paper tissue). 

The dilution of the antibodies has to be determined empirically Polyclonal antibodies can usually be diluted between 1.50 and 1.250 Monoclonal antibodies in tissue culture supernatant may need to be concentrated by centrifuging a frozen sample m a microfuge for 10 min and discarding the top third of the solution. This solution (100 pL) can then have the other primary antibody diluted into it in place of PBS-BSA Monoclonal antibodies produced as ascites can usually be diluted between 1-200 and 1 1000. 

Pellet the cells from 1-mL aliquots ofthe culture by centrifugation at 12,000g for 2 min in a microfuge, and resuspend the bacterial pellets in 360 pL of nutrient broth containing 10 mM MgS04. 

Resuspend the phage pellet in 2 mL PBS, and clarify by a short pulse of centrifugation in a microfuge. 

Transfer 1.5 mL of an overnight culture to a microfuge tube. Centrifuge the tube at 4000 X g for 5 minutes. 

Section 23.), dried and rinsed with distilled water before use. The advantage of these reaction vessels is that many of the reactions can be carried out successively in the same tube. Centrifugation of ethanol precipitates is rapid in the Eppendorf microfuge (12,000 g) and precipitates are collected as barely visible pellets at the bottom of the tube. 

These are small bench-top centrifuges for use with Eppendorf 1.5 ml snap-cap microfuge tubes. An essential piece of equipment for all sequencing work. 

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