Wirkung von EDTA auf Sporulation,Kompetenz und potentielle Tranformanten von Bacillus subtilis

Zusammenfassung 1–5·10^–4 M EDTA verhinderte selektiv die Sporenbildung, wenn es zur Zeit t ₀–t ₃ zu Stickstoff-limitierten Bacillus subtilis-Kulturen gegeben wurde.EDTA beeinflußte in den genannten Konzentrationen nicht selektiv die Ausbildung kompetenter Zellen, die Transformationsrate war nicht vermindert. Jedoch hatte es eine spezifische stabilisierende Wirkung auf potentielle Transformanten. Aus diesen Ergebnissen wird gefolgert, daß kompetente Zellen keinen sporulationsspezifischen Stoffwechsel aufweisen. Erst, nachdem bei weiterer Bebrütung die Kompetenz verloren gegangen ist, verhalten sich diese Zellen wie Präsporen. Die stabilisierende Wirkung des EDTA auf potentielle Transformanten beruht dann auf der Konservierung des frühen, reversiblen Sporulationsstadiums.Kompetenz scheint ein Präsporulationsstadium zu sein, das ausgebildet wird in den Zellen, die in Anwesenheit von C- und N-Kataboliten zur Sporulation übergehen.

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Action of EDTA on sporulation, competence and potential transformants of Bacillus subtilis

Summary The formation of spores in a nitrogen-limited Bacillus subtilis-culture was suppressed selectively by addition of 1-5·10^-4 M EDTA during the first 3 hours of sporulation.EDTA at the concentrations mentioned did not alter the frequency of transformation when added to a young growing culture. The development of competent cells was not affected to a higher extent than the growth rate. However, a specific action of EDTA on potential transformants could be demonstrated. The presence of EDTA caused their stabilization for more than 5 hours. From these results ist was concluded that there is no sporulation specific metabolism in competent cells. Only after having lost their competence during further incubation they resemble forespores. The stabilizing effect of EDTA on potential transformants may then be caused by conserving the early, reversible phase of sporogenesis.Competence seems to represent a presporulation-state which occurs in cells which are going to sporulate in the presence of C- and N-catabolites.

     

Insect-catching behavior in socially inexperienced infant squirrel monkeys

Insects are an essential component of squirrel monkey natural food. Eight of ten socially inexperienced infant squirrel monkeys, during their 2nd and 3rd month of age, directed their attention to living insects or film presentations of moving insects. They attempted to catch them with gradually improving success, and on at least two occasions consumed them. For comparison, group-living squirrel monkeys begin to eat solid food around their 2nd month of age, continuing with some nursing until about 11 or 13 months, and were only at this age seen to successfully catch and eat insects. Thus, as infant squirrel monkeys proved to be able to catch and eat insects before their first experience with conspecifics, an innate basis for this behavior can be assumed.     

Greater Soil Carbon Sequestration under Nitrogen-fixing Trees Compared with <Emphasis Type="Italic">Eucalyptus</Emphasis> Species

Forests with nitrogen-fixing trees (N–fixers) typically accumulate more carbon (C) in soils than similar forests without N–fixing trees. This difference may develop from fundamentally different processes, with either greater accumulation of recently fixed C or reduced decomposition of older soil C. We compared the soil C pools under N–fixers with Eucalyptus (non–N–fixers) at four tropical sites: two sites on Andisol soils in Hawaii and two sites on Vertisol and Entisol soils in Puerto Rico. Using stable carbon isotope techniques, we tracked the loss of the old soil organic C from the previous C₄ land use (SOC₄) and the gain of new soil organic C from the C₃, N–fixer, and non–N–fixer plantations (SOC₃). Soils beneath N–fixing trees sequestered 0.11 ± 0.07 kg m⁻² y⁻¹ (mean ± one standard error) of total soil organic carbon (SOC_T) compared with no change under Eucalyptus (0.00 ± 0.07 kg m⁻² y⁻¹; P = 0.02). About 55% of the greater SOC_T sequestration under the N–fixers resulted from greater retention of old SOC₄, and 45% resulted from greater accretion of new SOC₃. Soil N accretion under the N–fixers explained 62% of the variability of the greater retention of old SOC₄ under the N–fixers. The greater retention of older soil C under N–fixing trees is a novel finding and may be important for strategies that use reforestation or afforestation to offset C emissions. Received 12 March 2001; accepted 5 October 2001.     

Die Wirkung von Ultraschall auf die O2-Aufnahme und die anaerobe CO2-Abgabe von Hefezellen

Ohne ZusammenfassungDie Untersuchungen wurden mit Unterstützung der Deutschen Forschungsgemeinschaft durchgeführt.     

Starvation-Induced Multiresistance in Enterococcus faecalis JH2-2

Compared with growing bacteria, carbohydrate-starved cells of Enterococcus faecalis show development of a multiresistance state against heat, H₂O₂, acid, and ethanol, but not against UV irradiation. The kinetics of acquisition of resistance is different according to the stress. Three hours of starvation provide maximal resistance against ethanol, while the tolerance to heat, H₂O₂, and acid increases progressively with the duration of starvation. Chloramphenicol treatment does not abolish the ethanol tolerance. Protein synthesis inhibition during the transitional growth phase and the first hours of starvation partially inhibit the acquisition of heat and oxidative resistances. Antibiotic treatment after 3 h of starvation does not affect the increase of these resistances. We suggest that synthesis of specific proteins revealed by 2-D gel analysis in the first 3 h of starvation, followed by a second mechanism related to protein degradation or alteration, is necessary for acquisition of maximal resistance towards heat and oxidative stresses.     

Plant Protoplasts Immobilized in Calcium Alginate: A Simple Method of Preparing Fragile Cells for Transmission Electron Microscopy

A simple method for electron microscopic preparation of plant protoplasts is described. The main problems in preparing these fragile protoplasts for electron microscopy have been cell collapse due to steep gradients between protoplasts and fixatives and unacceptable loss of material during the many steps of the procedure. These problems may be solved by immobilization of the protoplasts in calcium alginate beads. The free diffusion properties of this gel prevent steep gradients. The beads also simplify handling and prevent loss of material. Protoplasts isolated from hypocotyls of rape, Brassica napus (var. Niklas), have been used as a model system. Transmission electron microscopy of the immobilized protoplasts osmotically stabilized with glucose demonstrated adequate structural and ultrastructural preservation.