Size and specific activity of the UTP pool and overall rates of RNA synthesis in early mouse embryos

Mouse embryos from the one-cell to the blastocyst stage were cultured for 2 hr in the presence of 5 μM [³H]uridine or 10 μM [³H]adenosine, and the size and specific activity of the UTP and ATP pools were determined by an Escherichia coli RNA polymerase assay using synthetic poly(dA-dT) as template. The total UTP pool increased in size and specific activity with development from 0.05 pmole (0.06% labeled) in the one-cell stage to 0.54 pmole (27% labeled) in the blastocyst stage. The total ATP pool remained relatively constant in size at about 1 pmole/embryo, but increased in specific activity from 2.6 to 52% from one-cell to blastocyst. The turnover of the [³H]UTP pool was also examined under pulse-chase conditions in eight-cell and morula-stage embryos. The UTP pool decayed with approximately first-order kinetics up to 20 hr of chase, but the rate of decay was slower in eight-cell embryos (t_0.5 = 5.5 hr) than in morulae (t_0.5 = 2.8 hr). The observed specific activities of the UTP pools were used to calculate the overall rates of uridine incorporation into acid-precipitable material during early development. The rate of uridine incorporation per embryo increased from 3.6 × 10^?3 pmole/2 hr in the two-cell embryo to 1.8 × 10^?1 pmole/2 hr in the blastocyst. The rate of RNA synthesis per cell over a 2-hr period was estimated at 2.5 pg in the two- to four-cell embryo, 5 pg in the eight-cell, and 10 pg in the morula-early blastocyst.     

Dosage effect of the cytoplasmic superoxide dismutase (SOD-1) gene in the erythrocytes of Down's syndrome patients]

The activity of cytoplasmic superoxydase (SOD-1) was studied in erthrocytes of 17 patients affected with Down's syndrome (trisomy 21) and in 26 healthy persons. A 1.56-fold increase of the enzyme activity was observed in the group of patients as compared with the control group. This could be explained as the dosage effect of the corresponding gene located in the chromosome 21.     

KINETICS OF BRAIN GLUTAMATE DECARBOXYLASE. INTERACTIONS WITH GLUTAMATE,PYRIDOXAL 5-PHOSPHATE AND GLUTAMATE-PYRIDOXAL 5-PHOSPHATE SCHIFF BASE1

Abstract— The kinetic behavior of glutamate decarboxylase from mouse brain was analyzed in a wide range of glutamate and pyridoxal 5′-phosphate concentrations, approaching three limit conditions: (I) in the absence of glutamate-pyridoxal phosphate Schiff base; (II) when all glutamate is trapped in the form of Schiff base; (III) when all pyridoxal phosphate is trapped in the form of Schiff base. The experimental results in limit condition (I) are consistent with the existence of two different enzyme activities, one dependent and the other independent of free pyridoxal phosphate. The results obtained in limit conditions (II) and (III) give further support to this postulation. These data show that the free pyridoxal phosphate-dependent activity can be abolished when either all substrate or all cofactor are in the form of Schiff base. The free pyridoxal phosphate-independent activity is also abolished when all substrate is trapped as Schiff base, but it is not affected by the conversion of free pyridoxal phosphate into the Schiff base. A kinetic and mechanistic model for brain glutamate decarboxylase activity, which accounts for these observations as well as for the results of previous dead end-inhibition studies, is postulated. Computer simulations of this model, using the experimentally obtained kinetic constants, reproduced all the observed features of the enzyme behavior. The possible implications of the kinetic model for the regulation of the enzyme activity are discussed.     

Use of carminomycin on adult patients with acute leukemias]

The data on the clinical trials of karminomycin, a new antitumor antibiotic are presented. The drug was used in the treatment of 46 adult patients with leukemia. Karminomycin was used in primary inducing therapy and treatment of relapses. The results of the trials showed that karminomycin had a definite therapeutic activity in treatment of acute myeloblast leukemia at various stages of the process. A rapid effect of the antibiotic provided its use in emergency cases with rapidly progressing variants of the disease.     

Dihydroteugin,a neo-clerodane diterpenoid from Teucrium chamaedrys

From the aerial part of Teucrium chamaedrys a new neo-clerodane diterpenoid, dihydroteugin, has been isolated, besides the previously known diterpenoids teucrin A and teugin. The structure of dihydroteugin, (12S)-15,16-epoxy-2β,6β-dihydroxy-neo-cleroda-13(16), 14-diene-18,19:20,12-diolide, was established by chemical and spectroscopic means and by partial synthesis from teugin.     

Test of the electro-ultrafiltration method's applicability in soil analysis. Reproducibility of the method

Summary The applicability of the Electro-Ultra-Filtration (EUF) method in soil analyses was studied. The reproducibilities of the amounts of soil extracts, of ion concentrations in the extracts and of the distribution of cations and anions over the cathode and anode extracts by use of fully automatic EUF equipment were tested. The degree of variability among replicates was expressed as coefficient of variation (CV) and as the highest percentual divergence of an individual analytical measurement from the mean (L). The extraction volumes of five replicates of six different soils were found to vary between 1.1–7.1% with an average of 3.8%, as CV and between 1.5–11.3% as L. The reproducibility of desorbed P in the anode extract varied between 2.7–31.7% with an average of 8.7%, as CV and between 3.2–37.9% as L. Corresponding values for CV and L of K desorbed varied between 1.3–13.9% and 1.6–23.8%, respectively. Variations among replicates of desorbed P were especially high in the first 1–2 sub-fractions of a total of seven fractions in a single extraction run. Low K concentrations in the extract had a slightly negative influence on the reproducibility of K desorption. Furthermore, it was found that a portion of the cations is collected in the anode extract and a portion of the anions in the cathode extract, especially at the beginning of an extraction run. Pooling of anode and cathode extracts before analysis is therefore recommended.     

Development of regulation mechanisms for SO42- influx in spring wheat roots

The development of SO₄^2- influx in roots and sulfur transport to shoots was followed in ³⁵S-tracer experiments for sulfur-deficient spring wheat (Triticum aestivum L. cv. Svenno) seedlings pretreated for various time periods (0–24 h) in nutrient solutions with SO₄^2-. Effects of the metabolic inhibitor 2,4-dinitrophenol (DNP) and the protein synthesis inhibitor cycloheximide (CH) on SO₄^2- influx were also evaluated. The SO₄^2- influx appears feedback-regulated by the internal sulfur level of the roots. Regulation may be achieved solely by a rapidly changed SO₄^2- carrier activity through an allosteric effect by the intracellular SO₄^2- concentration of the roots, followed first by induction of carrier synthesis and then by repression of carrier synthesis after transfer of the roots from SO₄^2--deficient nutrient solutions to solutions with SO₄^2-. A Hill plot of the partly sigmoidal relationship between SO₄^2- influx and intracellular sulfur concentration in the roots gave a Hill coefficient of -4.2, indicating negative cooperativity between a minimum number of four interacting allosteric binding sites for sulfur on each carrier entity. DNP-experiments showed that SO₄^2- influx was mainly metabolic, especially after short pretreatment in SO₄^2- at an external SO₄^2- concentration of 0.1 mM. Pretreatment with CH rapidly prevented new SO₄^2- carriers from being formed. Long CH pretreatment (24 h) and different SO₄^2- pretreatments reduced SO₄^2- influx below the non-metabolic level obtained by uptake experiments with DNP, indicating the existence of SO₄^2- carriers mediating passive SO₄^2- transport across the plasmalemma of the root cells. SO₄^2- influx was further decreased for the CH pretreated (24 h) plants by the presence of both CH and DNP in the experimental nutrient solution. This probably indicates the diffusive part of the non-metabolic SO₄^2- influx in the present experiments. Finally, it is suggested that there is a feedback signal between root and shoot, regulating sulfur transport upwards.