Mitochondrial DNA of the basidiomycete Polyporus ciliatus

Summary Mitochondrial (mt) DNA of the white rot fungus Polyporus ciliatus was isolated and characterized. As a result of detailed restriction enzyme analysis, a physical map was established showing that this circular DNA has a molecular weight of 88.2 kb. By heterologous cross hybridization the sites of three mt genes were recognized. By nonselective cloning of mt DNA fragments in Saccharomyces cerevisiae, an autonomously replicating sequence (ars) was identified which has potential application in the development of a prokaryotic/eukaryotic shuttle vector.     

Immunoelectron microscopic studies on the localization of peptidoglycan peptide subunit pentapeptides in bacterial cell walls

The peptide subunit pentapeptide H-L-Ala-D-Glu(L-Lys-D-Ala-D-Ala-OH)-NH₂ of peptidoglycan was localized in the cell walls of several Gram-positive bacteria employing the indirect immunoferritin technique. Specific antibodies to the D-alanyl-D-alanine moiety of non-crosslinked peptide subunit pentapeptide were raised in rabbits by immunization with synthetic immunogen albumin-(CH₂CO-Gly-L-Ala-L-Ala-D-Ala-D-Ala-OH)₃₉. Specificity of these antibodies for the peptide subunit pentapeptide and not for the peptide subunit tetrapeptide was corroborated in a Farr-type radio-active hapten binding assay. Specificity of labelling with ferritin was established by immunoelectron microscopic controls, and by the excellent correlation between specific labelling of cells with ferritin and the particular peptidoglycan primary structure of bacterial strains investigated. Cells of Lactobacillus gasseri, Streptococcus pyogenes and Staphylococcus aureus revealing non-crosslinked peptide subunit pentapeptides in their peptidoglycans could specifically be labelled. Lactobacillus acidophilus and Bacillus subtilis, on the contrary, missing such pentapeptides, failed in labelling.The implication of this method to possibly localize the points of attack of penicillin or cycloserine is discussed.Abbreviations used meso-A₂pm meso-diaminopimelic acid - DSM Deutsche Sammlung für Mikroorganismen, Göttingen, FRG This paper is dedicated to Professor Gerhart Drews on the occasion of his 60th birthday     

Effects of incubation in an atmosphere of 20% CO2 in air on the syrian hamster embryo clonal transformation assay

Summary An atmosphere containing 10% CO₂ has been generally accepted as optimal for the growth of Syrian hamster embryo cells in a clonal transformation assay. Data presented in this paper show that 10% CO₂ may not be the optimum environment for this assay. Using 10 or 20% (analytically measured) CO₂ in air (1 atm pressure), hamster embryo cell pools were examined for clonal growth characteristics and transformability using five known carcinogens and a single noncarcinogenic compound. At 10% CO₂, only 2 of 11 pools weee transformed by the five carcinogens but not by the noncarcinogen. At 20% CO₂, six of seven pools were transformed by the five carcinogens and not by the noncarcinogen. Further, the transformation frequencies were found to be greater in cultures incubated in an atmosphere consisting of 20% CO₂ in air. The data also show that 20% CO₂ increased the cloning efficiency of these cells. A comparison of the 10 and 20% CO₂ data to results reported from other conflicting interlaboratory results with this assay system may be due, in part, to variations of CO₂ concentrations. In some instances, the CO₂ levels indicated by incubator flow meters vary considerably from analytically determined CO₂ values. To prevent these CO₂ discrepancies and their resultant effects on transformation and cloning efficiency, methods for monitoring the CO₂ environment other than flow meters are recommended. The observation of increased cloning efficiencies and transformation rates strongly suggests that culture incubation at 20% CO₂ is a preferred environment for the conduct of this assay.     

Bruterfolg des Sumpfrohrs?ngers(Acrocephalus palustris) in Abh?ngigkeit von der Nistplatzwahl

Zusammenfassung Bei 267 Nestern des Sumpfrohrsängers(Acrocephalus palustris) im Rheinland wurden jeweils 6 verschiedene Habitatparameter erfaßt. Nur ca. 14 % der Bruten gingen durch Nesträuber verloren. Erfolgreiche Nester standen vorzugsweise auf feuchten Böden (an Bächen und Gräben) mit ausgedehnten, dichtstehenden Beständen hochstieliger Krautpflanzen, die guten Sichtschutz bieten. Ausgeplünderte Nester fanden sich gehäuft auf trockeneren Böden (Feldabgrenzungen) mit kleinflächigen, durchmischten und lockeren Krautbeständen, die nicht immer ausreichenden Sichtschutz bieten können. Der Sichtschutz wird sowohl durch vertikale Strukturelemente (Zahl der Krautstengel pro Fläche) als auch durch horizontale Elemente (Blätter und Verzweigungen in Nesthöhe) erreicht. Er beeinflußt den Bruterfolg am stärksten, gefolgt von der Größe des Krautbestandes, in der das Nest hängt. Relativ unbedeutend für das Auskommen der Brut waren Nesthöhe und Nistpflanzenspezies. Das Angebot optimaler Habitate war offensichtlich nur begrenzt vorhanden. Doch auch bei suboptimaler Habitateinpassung blieb der Bruterfolg im Vergleich zu einigen anderen Arten noch relativ hoch. Den Bruterfolg beeinflussende Faktoren und die Konsequenzen einer wahrscheinlich sehr guten Habitateinpassung des Nestes werden kurz diskutiert.

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Effects of nestsite selection on breeding success in the March Warbler(Acrocephalus palustris)

Summary During 1969–1973 and 1983 267 nests of Marsh Warblers were found in early breeding stages and controlled throughout the breeding cycle. At all nests 6 parameters describing habitat characteristics (as measures of nestsite selection) were measured. Failures due to other causes had been excluded. Only 14 % of nests were predated, presumably by mammalian predators mainly. There were marked differences comparing habitat characteristics of successfull and predated nests: Successfull nests were located preferably on moist grounds (along rivers and ditches) with large areas of herbaceous vegetation possessing a high density of stems, which offered a good nest cover (75–100 % concealment). Predated nests were found more frequently on dry grounds (field edges) with small areas of herbaceous vegetation having only a low density of stems. There is a reduced nest cover (under 50 % concealment). Nest cover is achieved by the amount of vertical structures (stems) as well as horizontal structures (leaves and twigs around the nest). Cover was the most important factor reducing predation followed by the size of areas of herbaceous vegetation containing the nest. Less important were nest height and plant species. Optimal habitats seemed to have only a limited availability. But even in suboptimal habitats breeding success was still relatively high compared to several other species. Factors influencing the breeding success and the consequences of a probably well, managed nestsite selection (habitat fitting) are discussed briefly.

     

Generation of nonspecific murine cytotoxic T cells in vitro by purified human interleukin 2

Murine spleen cells developed into nonspecific cytotoxic cells within 72 hr of culture in the presence of highly purified sources of human interleukin 2. In whole spleen cell cultures, human interleukin 2 generated effector cells which were Thy 1.2⁺, Lyt 2.2⁺, resistant to γ irradiation (1000 R), and capable of lysing both H-2 compatible and incompatible targets. The effector cells generated in this manner were not restricted to classical natural killer cell-sensitive targets. If thymus-derived cells (T cells) were depleted from the spleen cell population before culture with human interleukin 2, the effector cells generated were enriched in effectors capable of lysing natural killer cell-sensitive targets. Interferon was not produced in interleukin 2-stimulated spleen cell cultures. In addition, heterologous antibody to murine -γ-interferon did not abrogate the generation of cytotoxic cells by human interleukin 2. These and additional data suggest that human interleukin 2 is capable of stimulating γ-irradiation-sensitive Thy 1.2⁺ cell(s) capable of lysing a variety of target cells regardless of inherent sensitivities to classical natural killer cells. Thy 1.2^? cells were also stimulated by human interleukin 2 and lysed only natural killer cell-sensitive targets. Human interleukin 2 caused some Thy 1.2^? cells to become susceptible to lysis by anti-Thy 1.2 serum and complement.     

The case for a polyphyletic origin of mitochondria: Morphological and molecular comparisons

The comparative morphology and pigmentation of protists suggest that those with tubular mitochondrial cristae belong to a different lineage than those with lamellar cristae and that the evolutionary divergence might have been very early. We propose that the difference in cristal morphology is the result of separate origins of the mitochondria from endosymbionts related to the Rhodospirillaceae (purple nonsulfur bacteria) but differing in the morphology of their internal membranes. Comparisons of the cytochromes c of protists and the Rhodospirillaceae and of 16s rRNA T1 oligonucleotide catalogs in the Rhodospirillaceae do not contradict, and in fact provide support for, the idea. More extensive evidence may be lacking simply because cytochromes c have been studied in very few protists with tubular mitochondrial cristae.     

Chromosome Preparations in the Field from Mammals Long After Death

Chromosome preparations of high quality can be obtained from bone marrow cells of small mammals that have been dead for 20 hr or longer. The bone marrow is rinsed out of the femurs with RPMI medium supplemented with 15% fetal calf serum. Add 0.05-0.1 ml of a 0.01 % colchicine solution to 5 ml of medium-cell suspension. After Vi-1 hr of colchicine treatment at 37 C the cells are spun down and the supernatant replaced by 5 ml of hypotonic (0.075 M) KC1. After 12 min in the hypotonic solution at 37 C the cells are fixed in methanokacetic acid 3:1. Air dried preparations are made after repeating the fixation procedure three times and the chromosomes are stained with Gietnsa, if required after prclieatment of the preparations for banding; e.g., GTG. Technical hints for field work are given. The technique has proven successful with several species of rodents and shrews.     

Scleroblast cultures from the gorgonianLeptogorgia virgulata (Lamarck) (Coelenterata: Gorgonacea)

Summary Scleroblasts were separated from fragmented tissue of growing tips ofLeptogorgia virgulata and cultured using a modification of the technique of Rannou. Replacement of fetal bovine serum with horse serum seemed to increase scleroblast viability. Cell adhesion occurred from 14 to 43 d. Cultured scleroblasts demonstrated cell aggregation, spicule formation, and extrusion of spicules into the external medium. Cells showing spicules in the process of being extruded appeared on the average after 24 d of culture. Variability among cultures was marked with respect to both division and spicule formation. Healthy cultures were maintained for more than 4 mo. This work was supported by National Science Foundation grants PCM8201389 and DCB8502698. This is contribution No. 674 of Belle W. Baruch Institute for Marine Biology and Coastal Research, University of South Carolina.     

Selenocysteine lyase activity in a cysteine-requiring mutant ofEscherichia coli K-12

Selenocysteine lyase activity was detected in crude extracts from a cysteine-requiring mutant ofEscherichia coli K-12. The level of activity was the same whether cells had been grown aerobically or anaerobically, with or without selenocysteine. Selenocysteine lyase catalyzes the conversion of selenocysteine to alanine and elemental Se, a reaction that is followed by a nonenzymatic reduction of the Se to hydrogen selenide. Both of these end products were identified in this study. With cysteine as the substrate, alanine and H₂S were formed, but only at levels 50% less than the products formed from selenocysteine. Selenocysteine lyase has been identified in a number of mammals and bacteria; its presence in a cysK mutant ofE. coli K-12 suggests a common route whereby hydrogen selenide, derived from selenocysteine, can then be assimilated into selenoproteins.     

Response of muscle protein turnover to insulin after acute exercise and training.

To determine whether the enhanced insulin-sensitivity of glucose metabolism in muscle after acute exercise also extends to protein metabolism, untrained and exercise-trained rats were subjected to an acute bout of exercise, and the responses of protein synthesis and degradation to insulin were measured in epitrochlearis muscles in vitro. Acute exercise of both untrained and trained rats decreased protein synthesis in muscle in the absence or presence of insulin, but protein degradation was not altered. Exercise training alone had no effect on protein synthesis or degradation in muscle in the absence or presence of insulin. Acute exercise or training alone enhanced the sensitivities of both protein synthesis and degradation to insulin, but the enhanced insulin-sensitivities from training alone were not additive to those after acute exercise. These results indicate that: a decrease in protein synthesis is the primary change in muscle protein turnover after acute exercise and is not altered by prior exercise training, and the enhanced insulin-sensitivities of metabolism of both glucose and protein after either acute exercise or training suggest post-binding receptor events.