Continuous culture of Candida boidinii variant 60 growing on methanol

Summary A new variant, Candida boidinii variant 60, which is less sensitive to methanol and formaldehyde shocks was grown in continuous cultures with methanol as sole carbon source. The substrate concentration in the feeding medium was either 1% methanol or 3% methanol. Biomass production, methanol consumption, the formation of formaldehyde and gas exchange were measured at different dilution rates. With low methanol feeding (10 g/l) maximal productivity of 0.44 g biomass/l·h is obtained at a dilution rate of 0.14 h^–1. Maximal specific growth rate is 0.18 h^–1. A yield of 0.32 g biomass/g methanol was obtained and the respiration quotient was determined as 0.55. Independently of initial substrate concentration, biomass decreases if methanol and formaldehyde are accumulating in the culture broth.In the culture with high methanol feeding (30 g/l) cell concentratioon increases up to 9 g/l at D=0.04 h^–1. At higher dilution rates methanol and form-aldehyde appear in the medium. Formaldehyde is then preferably oxidized without energy advantages for the cells. It seems that this enables the cells to overcome toxic effects caused by methanol and formaldehyde.     

Active domains in wild-type and mutant glucocorticoid receptors.

[3H]Triamcinolone acetonide was used to tag covalently specific glucocorticoid receptors by photoaffinity labelling at lambda greater than or equal to 320 nm. Receptors of wild-type mouse lymphoma cells and two glucocorticoid resistant mutants of "nuclear transfer deficient" (nt-) and "increased nuclear transfer" (nti) phenotypes, respectively, were used. Wild-type and nt- receptors yielded radiolabelled polypeptide bands of mol. wt. 98 000 as revealed by gel electrophoresis under denaturing conditions and fluorography. In contrast, the nti receptor had a mol. wt. of 42 000. Partial proteolysis of the wild-type receptor with alpha-chymotrypsin resulted in a fragment of mol. wt. 39 000 which still contained the steroid binding site but had increased affinity for DNA indistinguishable from that of the nti receptor. Chymotrypsin thus removed a domain from the wild-type receptor polypeptide which is involved in modulating DNA binding. The same domain is missing from the nti receptor.     

Growth of the yeast Hansenula anomala with nitrate as sole source of nitrogen under aerobic and anaerobic conditions

Summary The oxygen requirement ofHansenula anomala growing in batch culture on nitrate as sole source of nitrogen was examined. An aeration rate of 0.03 vvm or a constant oxygen partial pressure of 0.01 bar is sufficient for optimal growth.     

Determinants of skin contact pressure formation during non-invasive ventilation

There is no published data about mask features that impact skin contact pressure during mask ventilation.To investigate the physical factors of skin contact pressure formation.We measured masks with original and reduced air cushion size and recorded contact pressure. We determined cushion contact and mask areas by planimetric measurements.Contact pressures necessary to prevent air leakage during inspiration exceed inspiratory pressure by 1.01±0.41 hPa independent of cushion size.Contact area, ventilator pressure and mask area during inspiration and expiration impact contact pressure. Mask contact pressures are higher during expiration. The contact pressure increases with increase in inspiratory pressures independent of the ventilator cycle. During expiration, the contact pressure will increase in proportion to the expiratory pressure reduction of the ventilator. The mask with reduced air cushion size developed higher contact pressures.Contact pressure can be reduced by selecting masks with a small mask area in combination with a large mask cushion.     

125I-endothelin-1 and 125I-big endothelin-1 in rat tissues: autoradiographic localization and receptor binding.

The potent vasoconstrictor peptide, endothelin-1 (ET-1), which exhibits a characteristically long-acting activity in vitro and in vivo, is thought to be generated in endothelial cells from a less active intermediate, big endothelin-1 (big ET-1). In addition to ET-1, big ET-1 is also present in the circulation. The autoradiographic localization of 125I-big ET-1 and 125I-ET-1 has been studied after intravenous administration in rat tissues. Highest enrichment of radioactivity was found in the kidney cortex for both peptides. Compared to blood levels, enrichment of radioactivity is also detected, in the vascular wall of the aorta. Comparing the radioactivity pattern of ET-1 and big ET-1, a nearly identical tissue distribution is observed, with the exception of the relative enrichment in the lung and the zona glomerulosa after administration of ET-1. Both radioligands show a specific and saturable binding to lung and kidney membranes. In the case of lung tissue, Ki values are 10(-10) M for endothelin-1 and 10(-8) M for big endothelin-1. This difference in affinities may account for the lack of binding of big endothelin-1 to lung tissue.     

Xylose fermentation by yeasts

Summary Xylose reductase from the xylose-fermenting yeastPichia stipitis was purified to electrophoretic homogeneity via ion-exchange, gel and affinity chromatography. At physiological pH values the thermodynamic equilibrium constant was determined to be 0.575x10¹⁰ (l·mol^-1). Product inhibiton studies are reported which clearly show that the kinetic mechanism of the xylose reductase is ordered-bi-bi with isomerisation of a stable enzyme form.     

Xylose fermentation by yeasts. 5. Use of ATP balances for modeling oxygen-limited growth and fermentation of yeast Pichia stipitis with xylose as carbon source

Kinetic studies are presented for the growth and fermentation of the yeast Pichia stipitis with xylose as the carbon source. Ethanol is produced from xylose under anaerobic as well as under oxygen-limiting conditions but only at dissolved oxygen concentrations up to 3 mumol/L Maximum yields and production rates were obtained under oxygen-limiting conditions, where the xylose metabolism may be considered to be consisted of three different components (assimilation, respiration, fermentation). The contribution of each pathway is determined by the availability of oxygen and the energy yield of each pathway. In order to describe the course of oxygen-limited fermentations, a mathematical model has been developed with the assumption that growth is coupled to the energy production. The resulting model requires only four independent parameters (Y(x/O(2) ), Y(ATP) (max), m(ATP), and P/O). These parameters were estimated on the basis of eight separate batch fermentations.     

Untersuchungen über die chemische Zusammensetzung des Zellsaftes der DiatomeeCoscinodiscus wailesii (Bacillariophyceae,Centrales)

Zusammenfassung 1. Die vorläufigen Ergebnisse von chemischen Analysen des Zellsaftes vonCoscinodiscus wailesii werden mitgeteilt und den vonBeklemishev et al. (1961) an Zellsaftproben vonEthmodiscus rex gewonnenen Resultaten gegenübergestellt.2. Eine eingehende kritische Diskussion der beiderseitigen, völlig widersprüchlichen Ergebnisse liefert keine Anhaltspunkte zur befriedigenden Erklärung dieser Diskrepanzen, die weiteren Untersuchungen vorbehalten bleiben muß.

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Investigations on the chemical composition of the cell sap in the diatomcoscinodiscus wailesii (bacillariophyceae, centrales)

A sample of cells of the plankton diatomCoscinodiscus wailesii was cultivated at 15° C under 14 hours illumination per day by fluorescent lamps (ca. 1000 lux). The aerated culture medium consisted of Erdschreiber solution of about 30 salinity enriched (afterLewin 1965) with B (5 · 10^–5 m) and provided with infusorial earth (1 g/l) as a source of Si and trace elements. When the cell concentration reached about 100 per ml the diatoms were sifted off by a piece of plankton cloth (mesh width 200µ) and rinsed on the sieve by artificial Li-sea-water. After this treatment most of the Li-solution still adhering was removed by filter paper; the remaining rest imbibed in the free accessible room of the cytoplasm as well as in the cell walls and in interstitial rooms between cells was determined by flame photometry as apparent free space (AFS). All results were obtained from a single sample only; they have therefore to be regarded as preliminary. Comparing these results with the information revealed by former investigations on the cell sap of other marine algae (Kesseler 1964, 1966) no uncommon facts could be established: Potassium and chloride proved to be the main intracellular ions, while sodium was restricted to about 0.25 times its medium concentration; NH ₄ ^· was not detectable. Mg^··, Ca^··, and H₂PO₄ were present in relatively small amounts, while the sulfate concentration was rather high, and thus obviously compensating for the deficit in chloride ions. Similar relations, but more pronounced, were found inDesmarestia viridis. Acidity of cell sap, determined by means of Merck indicator paper, was p_H 5. Considering the dilution of the sample by the artificial Li-sea water, and the buffering effect of H₂PO₄ ions (probably from the cytoplasm), the p_H of the original sap might have been about 4. The specific gravity of artificial sap (prepared in agreement with the analytical results and determined arcometrically) was 1,0287 g/cm³ at 20° C, while the density of the culture medium, at the same temperature, was 1,0243 g/cm³. The chemical properties of the cell sap ofCoscinodiscus wailesii provide in no way suitable means of buoyancy, as could be demonstrated for the cell sap ofNoctiluca (Kesseler 1966). This finding contradicts results by the Russian investigatorsBeklemishev,Petrikova &Semina (1961) employing ultramicrochemical methods on samples of cell sap from single cells of the rather closely related giant speciesEthmodiscus rex.

     

Zur Bestimmung des Volumens biologischer Objekte

Zusammenfassung 1. Es wird eine Glasapparatur zur Bestimmung des Volumens biologischer Objekte beschrieben.2. Die Genauigkeit der Methode und die Reproduzierbarkeit der Ergebnisse werden an Hand einer Meßreihe dargestellt.

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On the volume determination of biological objects

A new simple glass-made apparatus for very exact volume determinations of biological material is described. The accuracy and reproducibility of the measurements are demonstrated.

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Herrn Professor Dr.Adolf Bückmann zum 65. Geburstag in Verehrung gewidmet.