Bovine colostrum or milk as a serum substitute for the cultivation of a mouse hybridoma

A mouse-mouse hybridoma was grown in serum-free medium supplemented with bovine milk or colostrum. Bovine colostrum supported growth of the hybridoma whereas bovine milk alone did not support cellular proliferation. For growth in medium supplemented with colostrum, the maximum cell concentration achieved was 1.4 x 10(6) cells/mL in 2.2% colostrum, which is 44% of that obtained in 9% serum. When cells were grown in media containing milk and low amounts of serum (<1%) the maximum cell concentration in 2.2% milk with 0.4% serum was 2 x 10(6) cells/ml, whereas it was only 0.2 x 10(6) cells/ml and 1.3 x 10(6) cells/ml in 2.2% milk alone and 0.4% serum alone, respectively. Similar behavior was observed for growth in media containing colostrum and low amounts of serum. The monoclonal antibody production in media containing combinations of serum and milk or colostrum was comparable to that obtained in media with higher serum concentrations. Experiments performed with conditioned media suggest that the rapid decrease in viability, after the maximum cell concentration has been reached, is partially due to the presence of some inhibitory components generated during the cell culture rather than due to depletion of some serum components.     

Transplantation of the chick early eye primordium into a lensectomized optic cup of a host embryo

Eye primordia of young chick embryos (stage XII) were transplanted into lensectomized optic cups of older embryos (stage XVII) to analyze the influence of the host retina on the degree of morphological differentiation attained by the donor lens. Embryos were sacrificed 24-96 h later. The donor lens primordium showed a differentiation more in correlation with the host eye cup (stage XXIII) after 24-96 h of incubation.     

Interaction of surfactants with model and biological membranes. II. Effect of N-alkyl-N,N,N-trimethylammonium ions on phosphatidylcholine bilayers as studied by spin probe ESR

The interaction of N-alkyl-N,N,N-trimethylammonium (CnTMA, n = 6-18) salts (iodides and/or bromides) with model membranes prepared by hydration of egg yolk phosphatidylcholine (EYPC) over aqueous salt solutions has been studied by m-doxyl stearic acid (m-DSA, m = 12 and 16) spin probe method. In disoriented EYPC bilayers the CnTMA salts decrease the orientational order parameter S33 of m-DSA evaluated from the powder pattern ESR spectra. This effect is maximal for C6TMA. In oriented EYPC bilayers prepared by the parallel-beam sputtering method and hydrated over saturated NaCl solution the order parameter S33 calculated from the angular dependence of the nitrogen hyperfine splitting is decreased in the presence of C6TMA. The order parameter S11 obtained from the angular dependence of line positions indicates deviation of m-DSA motion from axial symmetry. C6TMA increases the probability of gauche conformations of the lipid chains by about 13-14%, and decreases the effective energy difference between the trans and gauche conformations by about 420-480 J/mol, at molar ratio of EYPC/C6TMA = 2:1. The angular dependence of linewidths is analysed by employing a theory of spin relaxation based on the strong collision model for molecular reorientations. The correlation time tau 0 of the reorientation of an axis orthogonal to the doxyl ring of 16-DSA is decreased in the presence of C6TMA, while that of 12-DSA is not influenced by it. The ratio of tau 2/tau 0 is increased in the presence of C6TMA for the both spin probes. The results are explained using the free-volume model of the CnTMA-EYPC membrane interaction.     

Phospholipid turnover during phagocytosis in human polymorphonuclear leucocytes

We have previously observed that the phagocytosis of zymosan particles coated with complement by human polymorphonuclear leucocytes is accompanied by a time- and dose-dependent inhibition of phosphatidylcholine synthesis by transmethylation [García Gil, Alonso, Sánchez Crespo & Mato (1981) Biochem. Biophys. Res. Commun. 101, 740–748]. The present studies show that phosphatidylcholine synthesis by a cholinephosphotransferase reaction is enhanced, up to 3-fold, during phagocytosis by polymorphonuclear cells. This effect was tested by both measuring the incorporation of radioactivity into phosphatidylcholine in cells labelled with [Me-¹⁴C]choline, and by assaying the activity of CDP-choline:diacylglycerol cholinephosphotransferase. The time course of CDP-choline:diacylglycerol cholinephosphotransferase activation by zymosan mirrors the inhibition of phospholipid methyltransferase activity previously reported. The extent of incorporation of radioactivity into phosphatidylcholine induced by various doses of zymosan correlates with the physiological response of the cells to this stimulus. This effect was specific for phosphatidylcholine, and phosphatidyl-ethanolamine turnover was not affected by zymosan. The purpose of this enhanced phosphatidylcholine synthesis is not to provide phospholipid molecules rich in arachidonic acid. The present studies show that about 80% of the arachidonic acid generated in response to zymosan derives from phosphatidylinositol. A transient accumulation of arachidonoyldiacylglycerol has also been observed, which indicates that a phospholipase C is responsible, at least in part, for the generation of arachidonic acid. Finally, isobutylmethylxanthine and quinacrine, inhibitors of phosphatidylinositol turnover, inhibit both arachidonic acid generation and phagocytosis, indicating a function for this pathway during this process.     

Basic electrophysiological parameters and frequency sensitivity of the ventricular myocardium of human embryos

The basic electrophysiological manifestations of the ventricular myocardium of twelve 7- to 12-week human embryos were measured with a glass electrode and a programmed stimulation technique. The resting membrane potential value was 79.37 +/- 0.34 mV and the overshoot 32.7 +/- 0.57 mV; the action potential (AP) duration at 1 Hz stimulation frequency was 120.0 +/- 5.7 ms at AP plateau phase levels and 258 +/- 17 ms at the level corresponding to 95% repolarization. The duration of the AP was a function of the stimulation frequency. i.e. it altered in correlation to the stimulation programme fully developed frequency sensitivity). In stimulation with different frequencies the duration of the steady state AP was in an inverse relation to the stimulation frequency, the maximum changes being found in the terminal repolarization zone. An interpolated extrasystole mainly affected the duration of the plateau phase.     

Hypophysis effect on the topographical distribution of toad oviduct mucoprotein components

In the present work the effects of the hypophysis hormones on oviduct mucoprotein components distribution patterns were studied. Remarkable changes after treating the toad with hypophysis injections were apparent. The distribution pattern for hexose, sialic acid, hexosamine and phosphate from 18 hours hypophysis treated toads were found to be identical with those obtained from preovulatory period animals. On the other hand, the levels for mucoprotein components from hypophysis treated animals were found to be approximately one-half or more higher than those obtained from postovulatory period toads. Otherwise, hypophysis treatment of the toads in preovulatory period had not effect on the levels and distribution patterns of mucoprotein components. These results suggest that hypophysis hormones are involved in the increase of the oviduct secretory activity.     

Relationship between the composition of phospholipids and respiratory activity of choline-deficient mutants ofNeurospora crassa

Phosphatidylcholine is one of the most frequent phospholipid components of the inner mitochondrial membrane ofNeurospora crassa. Quantitative analysis of phospholipids of the wild strain ofNeurospora crassa and of its twocho mutants showed that these strains did not significantly differ in the content of phosphatidylcholine. Mutants cultivated in a medium without choline contained, as compared with the wild strain, an increased amount of phosphatidylserine and a decreased quantity of phosphatidic acid. Respiratory activity increased and sensitivity to inhibitors of respiration changed. It is likely that the presence of choline in the growth medium exerts a regulatory effect on the cell metabolism of these mutants.     

Methionine degradation inCandida utilis

Incubation of cell-free extracts ofC. utilis and its ethionine-resistant mutants with methionine, aspartate and alanine, and with various acceptor oxo-acids showed the presence of several transamination activities (Glu-Asp, Ala-Glu, Met-Glu, Met-Ala, Ala-Asp, but not Met-Asp). The lack of utilization of methionine by mec mutants appears to be due to a transport lesion.     

Effect of changed cultivation conditions on the morphology ofAspergillus niger and on citric acid biosynthesis in laboratory cultivation

Cultivation ofAspergillus niger 97A in baffled flasks on a shaker brings about metabolic changes demonstrated in increased citric acid biosynthesis, morphological changes and alterations in the mycelial cell wall.