No abstract

Summary -Human and bovine milks were used as serum substitute for cell cultures. Two whey fractions termed LBS65 and LELm prepared by different steps were routinely used for culturing hybridomas in our laboratory. They stimulated 3H-thymidine incorporation into hybridoma, but a minimum of 1% of fetal calf serum (FCS) was required when the cells were propagated in the long-term. ln this investigation, the chemical composition of LBS65 and LELm was studied in parallel to FCS composition. LBS65 and FCS had a total protein level of about 40 g/l, while LELm contained them at a concentration of 11 g/l. The amino acid content of FCS and LBS65 was very similar (about 4 000 urnol/l), whereas it was lower in LELm (about 300 umorl). Although the values of nitrogen cornpounds were different in LBS65 and LELm, these 2 whey fractions behaved similarly to a substitute of FCS. Whey fractions were low in sodium, and high in calcium compared to FCS. The cholesterol level was lower and triglycerides were higher in whey than in FCS. The ratio of unsaturated! saturated fatty acids varied from 1 whey fraction to another. It differed from the FCS ratio. FCS and whey fractions contained small amounts of steroid or peptide hormones. However, progesterone, 17-0H-progesterone, ACTH and cAMP concentrations were higher in the whey fraction than in FCS. Whey fractions are a complex medium containing various compounds able to promote cell growth. However, sorne unknown compounds present in FCS and absent in milk fractions are required in long-term cell culturing.bovine milk 1 whey 1 whey hormone 1 whey amino acid

No abstract

No abstract

The aim of the present work was to study the binding of [125I]-BLGA (beta-lactoglobulin variant A) to the plasma membrane fraction of hybrid cells. This binding increased as a function of time with on-rate and off-rate constant at 4.47 +/- 0.18 x 10(6) M-1 min-1 and 0.17 +/- 0.07 min-1, respectively (n = 3). The saturation study showed a single binding site type corresponding to a Kd at 8.26 +/- 2.98 nM and 14.02 +/- 2.61 x 10(12) sites per mg of the plasma membrane protein (n = 3). Competitive of binding BLGA was observed with BLGA, complexed with retinol and also with RBP (retinol-binding protein). Gel filtration of [125I]-BLGA incubated with Triton X-100 solubilized membrane showed the formation of a ligand-receptor complex. Cross-linking of the tracer to plasma membrane showed a complex with a M(r) at 69 kDa, suggesting a receptor M(r) of 51 kDa, as seen by autoradiography of SDS-PAGE.