The effect of age on enolase turnover in the free-living nematode, Turbatrix aceti.

The rates of synthesis and degradation of enolase and total soluble proteins slow with age in the free-living nematode, Turbatrix aceti. The half-lives are 73 and 58 h for soluble protein and enolase, respectively, in young organisms (5 days old). The respective figures are 163 and 161 h for old organisms (22–30 days old). Similar slowing of protein turnover occurs when the organisms are aged by a repeated screening procedure which avoids the use of fluorodeoxyuridine, an inhibitor of DNA synthesis normally added to aging cultures to obtain synchrony. The results support the idea that slowed protein turnover may be responsible for the formation of altered enzymes in old organisms.     

Trophic interactions in soils as they affect energy and nutrient dynamics. IV. Flows of metabolic and biomass carbon

Flows of biomass and respiratory carbon were studied in a series of propylene-oxide sterilized soil microcosms. One-half of the microcosms received three pulsed additions of 200 ppm glucose-carbon to mimic rhizosphere carbon inputs. Biotic variables were: bacteria (Pseudomonas) alone, or amoebae (Acanthamoeba) and nematodes (Mesodiplogaster) singly, or both combined in the presence of bacteria.Over the 24-day experiment, respiration was significantly higher in the microcosms containing the bacterial grazers. Biomass accumulation by amoebae was significantly higher than that by nematodes. The nematodes respired up to 30-fold more CO₂ per unit biomass than did amoebae. Similar amounts of carbon flowed into both respiratory and biomass carbon in microcosms with fauna, compared with the bacteria-alone microcosms. However, partitioning of available carbon by the microfauna varied considerably, with little biomass production and relatively more CO₂-C produced in the nematode-containing microcosms. The amoebae, in contrast, allocated more carbon to tissue production (about 40% assimilation efficiency) and correspondingly less to CO₂.     

The interaction of metal ions with nucleic acids. NMR, EPR, CD and spectrophotometric study of the copper (II) interaction with 6-ketopurine ribosides

The copper (II)-inosine system in water-DMSO solutions was investigated as a function of pH and the molar ratio between the ligand and copper(II) ion by the EPR, NMR, CD and visible absorption spectrometric methods. It was concluded that a simple M.[-N]L copper(II)-inosine 1:1 complex is formed over the pH range 1.4-5.0, while M.[-N]L2 complexes are present in the solutions of pH 5.0-6.2. From pH 6.2 to 7.8 a diamagnetic, hydroxybridged complex M2.(OH)2.[-N]L4 dominates. At pH values of 7.8-9.2 an insoluble, oxybridged species (M.O.[-N]L)n is formed in addition to the soluble paramagnetic M.[-N-1)L4 complex. Above pH 9.1 the nitrogenbridged polymeric complex (M.[-N-1].M[-N-7] )n is formed which is stable up to pH 12.5, and above pH 12.5 the only species found is the M.[-OH]L2 chelate complex in which inosine is coordinated to copper through the two ionized hydroxyl groups.     

Universal measuring site for the determination of tissue-impedance variations in relation to blood perfusion]

In view of the importance of impedance plethysmography requirements are formulated for a modern impedance measuring device basing on a long experience with this method of measurement. The principle mode of action of the measuring equipment and the pneumatics with the timing element are described. A number of recordings is shown to illustrate the universality of the measuring equipment.