Different structure of polytene chromosomes ofPhaseolus coccineus suspensors during early embryogenesis

Summary The pattern of DNA and RNA puffs in pair VII of polytene chromosomes has been investigated in the suspensor ofPhaseolus coccineus during early embryo development. The pattern of³H-TdR and³H-U incorporation has been also detected. Collected data indicate that: 1. both heterochromatic regions, p₁₁ and q_(111+112), of chromosome pair VII, organize large DNA puffs; 2. DNA puffs of both regions are specific of different embryo differentiation steps; 3. a seasonal influence on the DNA puffing seems also to be present, as demonstrated by the comparison of the results collected in two different crops; 4. the incorporation experiment by³H-TdR evidences that not all DNA puffs show clustered labeling; 5. the RNA puffing of the two regions seems also to be specific of determined embryo stages.     

Glucosylation of Teichoic Acid: Solubilization and Partial Characterization of the Uridine Diphosphoglucose:Polyglycerolteichoic Acid Glucosyl Transferase from Membranes of Bacillus subtilis

Polyglycerolteichoic acid:glucosyl transferase (TAG transferase), one of the three enzymes involved in the pathway leading to the glucosylation of teichoic acid in Bacillus subtilis 168, was investigated. During the early stages of the growth of B. subtilis, TAG transferase is predominantly a soluble enzyme found in the cytoplasm. As growth proceeds, the amount of soluble enzyme decreases and the proportion of insoluble, membrane-bound TAG transferase increases, reaching a maximal value at the close of the logarithmic phase. Data are presented which suggest that these are two forms of the same enzyme, or have some common component. The effects of chaotropic agents, such as sodium trichloroacetate and sodium perchlorate, on the cytoplasmic membrane were also studied. These data show that such compounds can effectively remove the TAG transferase from the membrane in a water-soluble form. A study of some of the physical properties of this solubilized enzyme suggests that there is little difference between the two forms of the enzyme. Experiments are described which indicate that the glucosyl transfer by both the membrane-bound and soluble enzymes is not mediated by lipids.     

Nature of Escherichia coli B(P1) Yielder Cells at the Time of Infection with Restricted T1

In the infection of Escherichia coli B(P1) with restricted T1, it was shown that yielder cells consist of both special and nonspecial cells. Special or predetermined yielders occurred only among the earliest yielders. In most instances, yielder-cell formation was most easily explained by assuming that the first step was a chance escape of the restricted phage DNA from the degrading enzyme of the restricting cell.     

Locus-specific Changes in Cell Wall Composition Characteristic of Osmotic Mutants of Neurospora crassa

The osmotic phenotype of Neurospora crassa is characterized by inhibition of growth at high osmolalities of growth medium. Mutations at six osmotic loci of linkage group I were examined to assess the biochemical and physiological effects of these mutants. Isolated cell walls from 23 osmotic strains were compared with the wild type with regard to quantitative levels of the following components: percentage of total dry weight, total glucose, alkali-soluble glucose, nonglucose carbohydrates, amino acids, glucosamine, galactosamine, and a compound tentatively identified as quinovosamine. The last component has not previously been observed in N. crassa cell walls. Although the cell wall dry weight content of osmotic mutants was not altered, walls isolated from all of the osmotic strains had less alkali-insoluble glucose than those from the wild type. In addition, all of the loci except cut exhibited other consistent differences from the wild type. The os-1, os-3, and os-5 mutants had low levels of alkali-soluble glucose. The os-3 and os-5 mutants had high levels of nonglucose carbohydrates, and flm-2 had a low level of nonglucose carbohydrates. The os-4 mutants had low levels of galactosamine and amino acids and high levels alkali-soluble glucose. An os-1 mutant, B135, produced less of the whole alkali-soluble fraction of the cell wall.     

A propos de quelques groupements végétaux observés entre monaco et gênes

Résumé Le climat chaud et humide de la Ligurie méditerranéenne détermine la réapparition de quelques groupements végétaux connus de la Catalogne et rares ou nuls en Languedoc: Inulo-Oryzopsietum miliaceae, Cichorio-Sporoboletum poiretii, Hyparrhenietum hirto-pubescentis, Rubo-Coriarietum.Le caractère particulier de la végétation ligure a été exprimé par des groupements spéciaux: Pistacio-Rhamnetum alaterni, qui remplace le Quercetum cocciferae, groupements à Ostrya carpinifolia et à Brachypodium pinnatum des endroits frais, groupements buissonnants à Erica arborea et Genista germanica, à Rosmarinus et Genista cinerea, Asplenio-Campanuletum macrorhizae des rochers, etc.

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Summary The warm and humid climate of the Mediterranean Liguria determines the reappearance of some communities, known in Catalonia, and seldom or not existing in Languedoc: Inulo-Oryzopsietum miliaceae, Cichorio-Sporoboletum poiretii, Hyparrhenietum hirto-pubescentis, Rubo-Coriarietum.The particular character of the Liguric vegetation is expressed in special communities: Pistacio-Rhamnetum alaterni, which replaces the Quercetum cocciferae, communities with Ostrya carpinifolia and with Brachypodium pinnatum in the fresh places, bushy communities with Erica arborea and Genista germanica, with Rosmarinus and Genista cinerea, Asplenio-Campanuletum macrorhizae of the rocks, and so on.

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Zusammenfassung Das warme und feuchte Klima der mediterranen Ligurie bestimmt das Wiedererscheinen einiger Pflanzengesellschaften, die in Katalonien bekannt sind, aber selten oder nicht in Languedoc vorkommen: Inulo-Oryzopsietum miliaceae, Cichorio-Sporoboletum poiretii, Hyparrhenietum hirto-pubescentis, Rubo-Coriarietum.Der eigenartige Charakter der ligurischen Vegetation ist in besonderen Pflanzengesellschaften ausgedrückt: Pistacio-Rhamnetum alaterni, das das Quercetum cocciferae ersetzt, Gesellschaften mit Ostrya carpinifolia und mit Brachypodium pinnatum der frischen Standorte, Erica arborea-Genista germanica-Silikatbodengebüsche, Rosmarinus-Genista cinerea-Kalkbodengebüsche, Asplenio-Campanuletum macrorhizae der Felsen usw.