T I B T E C H - M A Y 1986

Conditioned media for

Feeder cells including thymocytes, spleen cells, peritoneal exudate cells, and irradiated fibroblasts are used to improve the growth of hybridomas. However, the initiation and maintenance of hybridoma cultures is easier if the feeder cells can be replaced by soluble factors: the feeder cells are first grown separately and the conditioned medium (CM) is then used to grow the hybridomas.

hybridoma production

Peritoneal exudate cells have been used to produce CM but the media produced in this way are prone to microbial infection. Therefore a CM from mouse fibroblast cultures, L-CM, has been developed. The medium is relatively easy to produce: confluent layers of L-929 fihroblast cells were grown in RPMI 1640 medium supplemented with 10% fetal calf sermn; medium was harvested and passed

through a 22 ~m filter and stored at 4°C. The media could be stored for up to three months.

The L-CM improved all phases of monoclonal antibody production from B cell hybridomas (directly following fusion, after cloning a limit dilution, and in bulk culture in flasks) compared with conditioned media produced from peri- toneal exudate cells. There is also preliminary evidence that L-CM can increase the recovery of viable cells after cryopreservation in liquid nitrogen.

Walker, K. Z., Gibson, J., Axiak, S. M. and Prentice, R.L. (1986) J. Immuno]. Methods 88, 75-81

New microbore separation system

The Model 130A is a liquid chroma- tography system designed for microbore chromatography of protein and peptides. Its manufacturers, Applied Biosystems, Inc., claim the Model 130A can separate

and isolate proteins or peptides with 20 times less dilution than conventional HPLC, resulting in better sensitivity, reduced sample handling and the ability to use smaller samples for sequencing.

The Model 130A is available with a wide range of narrow-bore and microbore columns for reverse phase, ion exchange, and hydrophobic interaction chromato- graphy of proteins and peptides.

Applied Biosystems, Inc., 850 Lincoln Centre Drive, Foster City, CA 94404, USA.

Rapid extraction of plasmids

Two methods have been described for the isolation of plasmids from C]ostridium peffringens both of which are quicker than equivalent density gradient procedures. Thefirstmethod is a micro modification of the conventional density gradient centri-

from Clostridium perfringens

fugation method for the extraction of plasmids from C. perfringens while the second is an adoption of a method described for the isolation of large plasmids from bacteria. The methods are described as relatively easy to perform,

requiring small volumes of culture and relatively inexpensive equipment.

Mahoney, D. E, Clark, G.A., Stringer, M. F., MacDonald, M. C., Duchesne, D. R. and Mader, J.A. (1986) Appl. Environ. Microbio]. 51,521-523

Automated immunoaffinity chromatography An efficient, low cost automated system for affinity chromatography has been described. The columns used in the system were cyanogen bromide-activated Sepharose 4B to which monoclonal antibodies were coupled. When the column has been loaded, up to 15 separate steps can be programmed for each cycle of the system but its basic operation involves

seven functions: an initial wash of the column, injection of the sample to be purified, a wash to remove unbound components of the sample, a high ionic strength wash to remove the bound antigen of interest, a third wash, elution of the column, and a final wash. Progress of the cycle was followed by monitoring the reservoir containing the sample and the

UV absorption of the ehrate from the column.

The column capacity remained stable (it could absorb 80% of its initial capacity after 100 cycles). A typical cycle would last three hours and would yield 23- 120 mg of antigen per cycle.

Bazin, H. and Malache, J-M. (1986) ]. lmmuno]. Methods 88, 19-24

Anaerobic rotating contact reactor

Methane yields of up to 0.093 litres per film structure of parallel plastic discs gram of volatile solids and productivities mounted on a horizontal shaft. Between up to 1.89 litres per day per litre of reactor the discs was an array of rectangular volume (at a hydraulic retention time of i scrubbers to scrape off excess bacterial day) were produced from dairy manure in film from the discs, thereby maintaining a an anaerobic reactor, constant reactor working volume. The

The reactor had a working volume of surface to volume ratio of the reactor was 5.5 litres and consisted of a rotating fixed 100.2 m2m -3,

The authors state that the reactor was viable and practical, giving a consistent performance and providing treatment for biodegradable dairy manure with chemi- cal oxygen demand concentrations of between 4.53 and 6.23 grams per litre.

Lo. K. V., Chert, W.Y. and Liao, P.H. (1986) Biomass 9, 81-92.

(~ 1986, Elsevier Science Publishers B.V., Amsterdam 0166-9430/86/$02.60