Synthesis of dinucleoside tetraphosphates by RNA polymerase B (II) from calf thymus

Highly purified RNA polymerase B (II) from calf thymus catalyses the synthesis of dinucleoside tetraphosphates from ribonucleoside triphosphates in the absence of an oligonucleotide primer or additional protein factors. The reaction requires a DNA template and bivalent cations such as Mn2+ or Mg2+. It is strongly inhibited by heparin and high concentrations of alpha-amanitin but not by rifampicin. On a given template various dinucleoside tetraphosphates of different sequence are formed although the yield depends on the nature of the template.     

Mutants with Altered Ca2+-Channel Properties in PARAMECIUM TETRAURELIA: Isolation, Characterization and Genetic Analysis

Dancers are a group of mutants in Paramecium tetraurelia whose Ca²⁺ current inactivates poorly and are likely to be defective in the structure of their Ca²⁺ channels. These mutants show prolonged backward swimming in response to K⁺ and Ba ²⁺ in the medium and were selected by this property in a galvanotactic trough. The dancer mutants are semidominant, and all isolated mutants belong to one complementation group; they are not allelic to any of the previously isolated behavioral mutants of P. tetraurelia. The phenotypic change from the homozygous parent to heterozygous F₁ generation takes three to five fissions. There is no evidence of a cytoplasmic factor capable of converting the dancer to the wild-type phenotype, as has been demonstrated in the mutants pawn and cnr. We suggest that the dancer locus is a structural gene for the Ca²⁺ channel.     

Extremely short 20-33 nucleotide introns are the standard length in Paramecium tetraurelia.

Paramecium tetraurelia has the shortest known introns as its standard intron length. Sequenced introns vary between 20 and 33 nucleotides in length. The intron sequences were discovered in genomic sequences coding for a variety of different proteins, including phosphatases, kinases, and low-molecular weight GTP-binding proteins. All intron sequences begin with the conserved dinucleotide GT and end with the conserved dinucleotide AG. The sequences are more AT rich than the Paramecium coding sequences. The identified sequences were confirmed as introns by sequencing several cDNA fragments. We report here analysis of the characteristics of 50 separate introns, including size, base composition, and a consensus sequence.     

Morphologische und statistische Untersuchungen an Zellkernen von Ratten und Mäusen zur Frage einer cytologischen Geschlechtsdiagnostik

Zusammenfassung An Blutausstrichen und Gewebsschnitten von männlichen und weiblichen Mäusen und Ratten wurde das Vorkommen von geschlechtsspezifischen morphologischen Kernmerkmalen untersucht. Die Kerne der neutrophilen Granulocyten weisen bei beiden Arten keine an den Kernanhängen erkennbare Geschlechtsdifferenz auf. An den Kernen der Parenchymzellen wurde für weibliche und auch für männliche Tiere ein positiver Geschlechtsnachweis auf Grund einer charakteristischen Chromatinverteilung geführt.Wir stimmen dem Vorschlag von Th. Lüers (1957) zu, die Begriffe Geschlechts-bestimmung und Geschlechtsdifferenzierung nur in ihrer ursprünglichen Bedeutung zu verwenden.     

Stochastic-rheological Simulation of Free-fall Arm Impact in Children: Application to Playground Injuries

The aim of this study was to develop and pilot a stochastic-rheological biomechanical model to investigate the mechanics of impact fractures in the upper limbs of children who fall in everyday situations, such as when playing on playground equipment. The rheological aspect of the model characterises musculo-skeletal tissues in terms of inertial, elastic and viscous parameters. The stochastic aspect of the model allows natural variation of children's musculo-skeletal mechanical properties to be accounted for in the analysis. The relationship of risk factors, such as fall height, impact surface, child mass and bone density, to the probability of sustaining an injury in playground equipment falls were examined and found to closely match findings in epidemiological, clinical and biomechanical literature. These results suggest that the stochastic-rheological model is a useful tool for the evaluation of arm fracture risk in children. Once fully developed, information from this model will provide the basis for recommendations for modifications to playground equipment and surface standards.     

Digestive and metabolic utilization of lauric,myristic and stearic acid in cows,and associated effects on milk fat quality

A study was carried out to examine the effect of dietary supplementation of oregano essential oil on performance of broiler chickens experimentally infected with Eimeria tenella at 14 days of age. A total of 120 day-old Cobb-500 chicks separated into 4 equal groups with three replicates each, were used in this study. Two groups, one infected with 5·10⁴ sporulated oocysts of E. tenella and the other not, were given a basal diet and served as controls. The other two groups also infected with E. tenella were administered diets supplemented with oregano essential oil at a level of 300 mg/kg, or with the anticoccidial lasalocid at 75 mg/kg. Following this infection, survival rate, bloody diarrhoea and oocysts excretion as well as lesion score were determined. Throughout the experimental period of 42 days, body weight gain and feed intake were recorded weekly, and feed conversion ratios were calculated. Two weeks after the infection with E. tenella supplementation with dietary oregano oil resulted in body weight gains and feed conversion ratios not differing from the non-infected group, but higher than those of the infected control group and lower than those of the lasalocid group. These parameters correspond with the extent of bloody diarrhoea, survival rate, lesion score and oocyst numbers and indicated that oregano essential oil exerted an anticoccidial effect against E. tenella, which was, however, lower than that exhibited by lasalocid.     

Yeast pyruvate kinase: essential lysine residues in the active site

1. Yeast pyruvate kinase was purified to near homogeneity and subjected to chemical modification by trinitrobenzenesulfonate and by P1, P2-bis (5' pyridoxal) diphosphate. 2. Labeled peptides were isolated and their amino acid composition was determined. 3. The results suggest that yeast pyruvate kinase has an essential lysine residue, and that this residue is in a location equivalent to an essential lysine described in the muscle enzyme. 4. Protection experiments indicate that this lysine is located at the nucleotide binding site.