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The nonkeratinous proteins of wool can be partly or completely dissolved by controlled enzymatic digestion. A comparison between the keratose content of intact wool and that of wool which has been hydrolysed for 96 h with pronase confirms that specifically all the nonkeratinous components are dissolved out of the wool composite by pronase. The influence of microbial infection can be excluded.

Summary This communication reports on the release of Mycoplasmavirus L 1 after infection ofAcholeplasma laidlawii with purified L 3 virus. Release also occurred after transfection with certain restriction fragments from MV-L3 and MV-L1 genomes. Since circular molecules are efficiently taken up in polyethylene glycol-mediated transfection, inducing fragments were applied cloned inE. coli plasmids. Release was also observed after electroporation of cells incubated with MV-L 1 replicative intermediate DNA and linear MV-L 3 DNA isolated from virus particles, respectively. Released MV-L 1 viruses were identified after virus plaque formation on indicator lawns according to plaque morphology and hybridization with labeled viral DNA probes as well as by DNA restriction analysis. Uninfected and untransfected cells from six laboratory strains ofA. laidlawii (including a MV-L 1 resistant one) were examined for the presence of MV-L 1 DNA. They all bear MV-L 1 DNA integrated in their genomes.

Viroids are uncoated infectious RNA molecules pathogenic to certain higher plants. Four different highly purified viroids were studied. By ultracentrifugation, thermal denaturation, electron microscopy, and end group analysis the following features were established: (i) the molecular weight of cucumber pale fruit viroid from tomato is 110,000, of citrus exocortis viroid from Gynura 119,000, of citrus exocortis viroid from tomato 119,000 and of potato spindle tuber viroid from tomato 127,000. (ii) Viroids are single-stranded molecules. (iii) Virods exhibit high thermal stability, cooperativity, and self-complementarity resulting in a rod-like native structure. (iv) Viroids are covalently closed circular RNA molecules.

Tellerium 135 and 137 nuclei were produced in thermal neutron fission of235U separated by on-line isotope separator and deposited on a movable tape. Gamma ray singles,?-?, ß-? coincidences and time sequenced? spectra were collected using Ge(Li) detectors and scintillator (NE 102 A) telescope. The half-lives and mass excesses of135Te and137Te were measured and level schemes of135I and135I have been established. The level scheme of135I has been compared to different shell model calculations.

A theory of transfection is developed which describes three different types of experiments in transfection: The concentration dependence of transfection, transfection with marker rescue, and the mapping function in transfection crosses. The theory is applicable to transfection systems exhibiting quadratic or higher order dose response (SPP1, SP50, SP82). It pictures the essential process in transfection as follows: transfecting DNA molecules, having suffered inactivating events during uptake or intracellularly, have to recombine prior to replication under elimination of these lesions. The probability for recombination, successful in this sense, is calculated as a function of the number of DNA molecules within the competent cell, the mean number of inactivating events per DNA molecule, and the crossover probability per nucleotide.

The content of 5-methylcytosine (5MC) and 6-methyladenine (6MA) in modified and nonmodified DNAs from B. subtilis and B. subtilis phage SPP1 were determined. Nonmodified SPP1 · O DNA contains about 15 5MC residues/molecule. Each modified SPP1 ·R DNA molecule carries 190 modification specific methyl groups. This number is sufficient to account for modification of the 80 restriction sites in SPP1 DNA (Bron and Murray, 1975) against endo R · Bsu R, assuming each modified site contains two 5MC residues. Resistance of SP01 DNA against endo R · Bsu R restriction both in vivo and in vitro is probably not due to methylation of endo R·Bsu R recognition sites.

Previous reports have suggested an increasing incidence of highly fluoroquinolone-resistant Escherichia coli causing bacteremia among cancer patients on prophylactic therapy. We used genotyping by pulsed-field gel electrophoresis of chromosomal DNA digests and random amplified polymorphic DNA fingerprinting to study clonal relationships among such isolates obtained at 10 cancer centers located across Europe and the Middle East. Analysis by both methods indicated that isolates from different centers were genotypically unrelated to each other. There were five centers from which more than one individual patient isolate was available, and most demonstrated significant within-center genetic diversity of strains. Strains shared among patients could be identified at two centers. At the center with the largest number of bloodstream isolates from cancer patients available, fluoroquinolone-resistant control isolates from surgical patients and fluoroquinolone-susceptible control isolates from patients admitted to medical services during the same time period were unrelated to resistant cancer patient isolates and to each other as well. A substantial number of fluoroquinolone-resistant isolates (19 of 58) were nontypeable by pulsed-field gel electrophoresis. Fluoroquinolone resistance was commonly associated with multiple antibiotic resistance to chemically unrelated antibacterial agents irrespective of the origin of the isolates.

The kinetics of adsorption and growth of mycoplasmavirus MVL3 in Acholeplasma laidlawii 1305/68 host cells have been studied with one-step growth, premature lysis, and single-burst experiments. The virus was found to kill infected host cells. Virus release starts 90 min after infection and continues for about 10 to 15 h. Hence, virus production is unlike the classical lytic bacteriophages and instead resembles nonlytic cytocidal animal viruses. Structural details of the virus are described, and the molecular weight of the viral linear DNA has beenfound to be 26 x 10(6).

The species spectrum, antibiotic susceptibility, and genomic profile of coagulasenegative staphylococci (CNS) isolated from infected preterm infants were compared with those obtained in CNS from nursery personnel.Staphylococcus epidermidis was the predominant species in the 66 investigated preterm infants (171 isolates), accounting for 64 % of all isolates. A high proportion ofStaphylococcus haemolyticus (32 %) could be detected. In contrast to the results in patients, the spectrum in nursery personnel was broad and included more species of CNS. All isolates of CNS from preterm infants demonstrated a low rate of susceptibility to the ß-lactam antibiotics (2 % sensitivity to penicillin and 6 % sensitivity to oxacillin). Sensitivity to gentamicin (9 %) was also rare. An unexpected observation was susceptibility to teicoplanin in only 70 % of all CNS isolated from patients due to the high proportion ofStaphylococcus haemolyticus. Analysis of the genomic profile of 33 isolates ofStaphylococcus haemolyticus by pulsed-field gel electrophoresis revealed a relationship between the strains. An outbreak of one particular strain ofStaphylococcus haemolyticus in the neonatal intensive care unit investigated can therefore not be excluded.

Mattox & Kendallhaben 1951 neben anderen Verbindungen auch das ?1-17(a)-oxy-21-acetoxy-pregnen-trion (3,11,20) dargestellt. Das Steroid, welches man vereinfachend auch 4,5-Dihydroprednison (N) – diese Bezeichnung wird im Folgenden als 4,5-DHP abgekürzt – nennen könnte, ist, wie aus der Bezeichnung entnommen werden kann, dadurch gekennzeichnet, dass es aus der Normalreihe abzuleiten ist und im Ring A die Doppelbindung zwischen C4und C5nicht mehr besitzt. Kürzlich haben Caspi & Pechet(1958) die Isolierung dieser Substanz aus dem Harn eines Addison-Patienten während der Behandlung mit Prednisolon beschrieben.Über die biologische Wirksamkeit der Substanz im Tierversuch sind, ausser einer vorläufigen Notiz aus unserem Arbeitskreis (Hohensee, 1958), keine Befunde bekannt geworden. In der vorliegenden Mitteilung wollen wir über einige Wirkungen des 4,5-DHP berichten.

Complexes of ribosomal protein S4 and 16S RNA appear as large blobs with tails when spread in the presence of 80% dimethylsulfoxide (DMSO). By comparing the length of the tail with the length of 16S RNA, it was calculated that a maximum number of about 700 nucleotides are involved in binding protein S4. It furthermore appeared that the protein is located at one end of the RNA molecule. The stability of the complex under the strongly denaturing conditions caused by DMSO was assessed in two ways: 1. the complex was stable when it was subjected to polyacrylamide gel electrophoresis after treatment with 80% DMSO, and 2. spider-like structures (indicating cross-linking) were observed in the electron microscope when a complex of protein S4, 16S RNA, and antibody against S4 had been treated with DMSO. As a further control protein S4 and 16S RNA were mixed under conditions of non-specific binding. No blob-with-tail structures were observed in the electron microscope.

The origin and the direction of replication of the SPP1 chromosome, which has a unique, nonpermuted sequence of markers, was established by determination of the frequency distribution of various markers along the SPP1 map. For this purpose replicating DNA was isolated from transfected competent B. subtilis cells. Marker frequencies were measured by means of helper mediated transfection. In the range defined by the genetic map, replication is unidirectional, originating from a point in the “left” part of the map. Shearing the DNA into halves prior to transfection permits only one round of replication of that half molecule which carries the origin.

Transfection with marker rescue techniques provides a sensitive assay for the DNA of phage SPP1. The method was used in a study of the process of replication of this phage. The data show that early during the eclipse, SPP1 DNA increases exponentially, suggesting a geometric mode of replication. DNA replication ceases at the time of the appearance of the first intracellular phage particles.

l'application de la technique électro-myographique à l'étude de l'activité électrique des muscles intrinsèques du larynx a été proposée pour la première fois par Weddel et al. (14) en 1944. Mais c'est seulement aucours de ce dernières années que les progrès de cette technique ont permis la réalisation de nouvelles investigations. Le travail de base est constituté par la thèse de Faaborg-Andersen (1, 2) réalisé dans le laboratoire du professeur Buchthal dont l'autorité mondiale en matiere d'électromyographie est un garant de la technique employée et de Interprétation des résultas. Mais des enregistrements de l'activité électrique des mucles intrinsèques du larynx ont également été publiés par Portmann et al. (6, 7, 8, 9), et par van den Berg (12,13), Spoor & van Dishoeck (10). En 1957, nous avons présenté à la Société de Laryngologie des Hôpitaux de Paris (4) les premiers enregistrements que nous avions pratiques chez une dizaine de malades.

A physical measure within a segment of the SPP1 genetic map was derived from the comparison of map positions of the molecular center of wild type and deletion mutant DNA.

Much greater amounts of small polydisperse circular DNA (spcDNA) have been detected, in cell cultures derived from angiofibromas of six patients with tuberous sclerosis (TS) than in those from the skin of these patients or from the skin of 11 healthy donors. This observation could be confirmed by spreading the DNA of appropriate fractions from CsCl density gradients. The findings suggest the existence of a relationship between the chromosomal instability observed in angiofibroma cultures and the mobilization of spcDNA.

In contrast to mycoplasma virus L1 and L2 circular DNA, mycoplasma virus L3 linear DNA is not biologically active in polyethylene glycol-mediated transfection. Electroporation of Acholeplasma laidlawii, however, leads to plaque formation after incubation with L3 DNA. The efficiency of electroporation-mediated transfection is 1/10 that of polyethylene glycol-mediated transfection as estimated with L1 DNA. Trypsin treatment of cells before DNA addition increases the efficiency of DNA uptake.

The new beta-delayed neutron emitter15B has been observed. The measured half-life is 11 ms ±1 ms and limits have been set on other decay channels: P0n<5%, P2n<1.5%. The beta emitter12Be has been separated, unambiguously identified, and its half-life has been measured to be 24±1 ms.

The structure and structural transitions of transcripts of cloned oligomeric viroid were studied in physico-chemical experiments and stability calculations. Transcripts of (+) and (−) polarity, from unit up to sixfold length, were synthesized from DNA clones of the potato spindle tuber viroid (PSTV) with the SP6 transcription system. Their structural properties were investigated by optical denaturation curves, high performance liquid chromato-graphy (HPLC), electron microscopy, sedimentation-diffusion equilibrium and velocity sedimentation. Secondary structures of the RNAs and theoretical denaturation curves were calculated using an energy optimization program. The secondary structure of lowest free energy for unit length and oligomeric transcripts is a rod-like structure similar to that of the mature circular viroids. When this structure is used as a model for calculations, there is a large degree of agreement between the theoretical and the experimental denaturation curves. At high temperatures, however, (+) strand transcripts exhibited a transition which was more stable than expected from the calculations or than was known from curves of mature viroids. This transition arises from a rearrangement of the central conserved region of viroids to a helical region of 28 stable base pairs either intermolecularly leading to bimolecular complexes, or intramolecularly giving rise to a branched secondary structure. The rearrangement could be detected by electron microscopy, HPLC, and analytical ultracentrifugation. The helical region serves to divide up the oligomeric (+) strand into structural units which may be recognized by cleavage and ligation enzymes which process the oligomeric intermediates to circular mature viroids.

Double mutations in the quinolone resistance determining region of the gyrase A gene (gyrA) have recently been reported to be associated with high-level resistance to fluoroquinolones in clinical isolates of Escherichia coli. We examined the type and frequency of such mutations in a large number of clinical isolates that were obtained from ten different geographical locations and had been genotypically characterized by pulsed field gel electrophoresis (PFGE) of chromosomal DNA digests. Of 36 isolates with ofloxacin MICs ≥4 mg/L that represented at least 24 distinct genotypes, 35 had double mutations at amino acid codons 83 and 87 of gyrA, while two isolates with ofloxacin MICs of 0.5 and 4 mg/L, respectively, each had a single mutation at codon 83. Mutations at codon Ser-83 were uniform, resulting in substitution by Leu. The additional mutations at amino acid codon 87 in the 35 double-mutants were diverse, resulting in Asp-87 substitutions by residues Asn (23 isolates), Gly (7 isolates), Tyr (4 isolates), or His (1 isolate) without a discernable correlation with fluoroquinolone MICs or with phenotypic resistance to chemically unrelated antibacterial agents. Maximal differences between MICs of double-mutants with the same amino acid substitution were eight-fold. The changes of amino acid residues at codon Asp-87 differed between individual patient isolates with the same genotype (and similar MICs), suggesting that the amino acid codon 87 mutations (and possibly the development of high-level fluoroquinolone resistance) might have occurred after the transmission and sharing of a precursor strain carrying the Ser-83→ Leu mutation.