Influence of nitrogen components of wine on the growth of lactic acid bacteria]

Three different fractions of nitrogen compounds have been extracted from wine: proteins, peptides, amino acids. They have been tested to support the growth of malolactic bacteria in acid medium: only the peptidic fraction supports this growth.     

Critical effects of epigenetic regulation in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized by persistent pulmonary vasoconstriction and pulmonary vascular remodeling. The pathogenic mechanisms of PAH remain to be fully clarified and measures of effective prevention are lacking. Recent studies; however, have indicated that epigenetic processes may exert pivotal influences on PAH pathogenesis. In this review, we summarize the latest research findings regarding epigenetic regulation in PAH, focusing on the roles of non-coding RNAs, histone modifications, ATP-dependent chromatin remodeling and DNA methylation, and discuss the potential of epigenetic-based therapies for PAH.     

Action of stannous and stannic chlorides on bacteria

Summary Stannous or stannic chlorides reduced the growth rate ofK. aerogenes, Ps. reptilovora and an unidentified bacterium in a minimal liquid medium and on agar plates. The greatest effect was observed withK. aerogenes and was accompanied by a decreased viability, but 100% survival occurred with the other strains. The metal was loosely bound to the cells and there was no direct correlation between the amount adsorbed and the biological response.We are indebted to the Wolfson Foundation for a grant for research on natural resources.     

Ethanol as a ‘food’ forDrosophila melanogaster: Influence of theEbony gene

Summary The survival time of adultDrosophila melanogaster flies without food is greater in the presence of ethanol, especially for flies of strains or lines with a higher alcohol dehydrogenase activity. It seems that theebony gene can act in some populations as a selective factor favoring the ADH^F allele, as well as the minor genes enhancing the alcohol dehydrogenase activity level.Chargé de Recherches au F. N. R. S.     

Ecology and physiology of phototrophic bacteria and sulfate-reducing bacteria in marine salterns

Marine salterns are habitats for a large variety of halophilic bacteria. In the anoxic zones, halophilic sulfur bacteria develop mainly at the sediment surface, but only a few of them have so far been isolated from such environments. Among the phototrophic sulfur bacteria that sometimes form purple layers underneath the green cyanobacterial layers, members of the generaEctothiodhodospira, Chromatium (C. salexigens), Thiocapsa (T. halophila) were isolated. They grow by using sulfide as an electron donor. In the marine salterns, sulfide originates from active sulfate reduction. Among the halophilic sulfate-reducing bacteria, onlyDesulfovibrio halophilus andDesulfohalobium retbaense have so far been isolated. The ecology and physiology of both kinds of bacteria are discussed in this paper.     

Effect of pH on bacteria in early log phase]

The bacteria harvested in the early log phase lyse when they are submitted to a pH above 10. The peptidoglycan is not degraded in these conditions. Thus, the authors used these properties to extract the peptidoglycan from several gram negative and gram positive bacteria.     

Surface display of a single-domain antibody library on Gram-positive bacteria

Combinatorial protein engineering for selection of proteins with novel functions, such as enzymes and affinity reagents, is an important tool in biotechnology, drug discovery, and other biochemical fields. Bacterial display is an emerging technology for isolation of new affinity proteins from such combinatorial libraries. Cells have certain properties that are attractive for directed evolution purposes, in particular the option to use quantitative flow-cytometric cell sorting for selection of binders. Here, an immune library of around 10⁷ camelid single-domain antibody fragments (Nanobodies) was displayed on both the Gram-positive bacterium Staphylococcus carnosus and on phage. As demonstrated for the first time, the antibody repertoire was found to be well expressed on the bacterial surface and flow-cytometric sorting yielded a number of Nanobodies with subnanomolar affinity for the target protein, green fluorescent protein (GFP). Interestingly, the staphylococcal output repertoire and the binders from the phage display selection contained two slightly different sets of clones, containing both unique as well as several similar variants. All of the Nanobodies from the staphylococcal selection were also shown to enhance the fluorescence of GFP upon binding, potentially due to the fluorescence-based sorting principle. Our study highlights the impact of the chosen display technology on the variety of selected binders and thus the value of having alternative methods available, and demonstrates in addition that the staphylococcal system is suitable for generation of high-affinity antibody fragments.     

Electron microscopic observation of bacteria growing on the skin surface

Résumé Des observations au microscope électronique ont été faites sur des bacteries se développant à la surface de la peau. En utilisant la technique de fixation deRyter-Kellenberger, les auteurs ont obtenu bonne préservation des microorganismes, ce qui a permis l'étude de leur fine structure.

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Supported in part by grants from the Eli Lilly Co., Indianapolis, Indiana and the Upjohn Co., Kalamazoo, Michigan. — We are indebted to Drs.S. H. Black, E. Kellenberger andR. P. Williams for their valuable suggestions. — We are also grateful to MissS. Martin, MissN. Moreland and Mr.G. Adams for their technical assistance.     

Propagation of histone marks and epigenetic memory during normal and interrupted DNA replication

Although all nucleated cells within a multicellular organism contain a complete copy of the genome, cell identity relies on the expression of a specific subset of genes. Therefore, when cells divide they must not only copy their genome to their daughters, but also ensure that the pattern of gene expression present before division is restored. While the carrier of this epigenetic memory has been a topic of much research and debate, post-translational modifications of histone proteins have emerged in the vanguard of candidates. In this paper we examine the mechanisms by which histone post-translational modifications are propagated through DNA replication and cell division, and we critically examine the evidence that they can also act as vectors of epigenetic memory. Finally, we consider ways in which epigenetic memory might be disrupted by interfering with the mechanisms of DNA replication.     

Heritable changeability: Epimutation and the legacy of negative definition in epigenetic concepts

Epigenetic concepts are fundamentally shaped by a legacy of negative definition, often understood by what they are not. Yet the function and implication of negative definition for scientific discourse has thus far received scant attention. Using the term epimutation as exemplar, we analyze the paradoxical like-but-unlike structure of a term that must simultaneously connect with but depart from genetic concepts. We assess the historical forces structuring the use of epimutation and like terms such as paramutation. This analysis highlights the positive characteristics defining epimutation: the regularity, oxymoronic temporality, and materiality of stable processes. Integrating historical work, ethnographic observation, and insights from philosophical practice-oriented conceptual analysis, we detail the distinctive epistemic goals the epimutation concept fulfils in medicine, plant biology and toxicology. Epimutation and allied epigenetic terms have succeeded by being mutation-like and recognizable, yet have failed to consolidate for exactly the same reason: they are tied simultaneously by likeness and opposition to nouns that describe things that are assumed to persist unchanged over space and time. Moreover, negative definition casts the genetic-epigenetic relationship as an either/or binary, overshadowing continuities and connections. This analysis is intended to assist practitioners and observers of genetics and epigenetics in recognizing and moving beyond the conceptual legacies of negative definition.     

Excretion of porphyrins by bacteria

Zusammenfassung Escherichia coli, Pseudomonas aeruginosa undAchromobacter metalcaligenes bilden sämtliche, der Biosynthesekette zum Häm entsprechenden Porphyrine aus endogener -Aminolävulinsäure (ALS) und scheiden Koproporphyrin und Häm aus. Porphyrinsynthese-stimulation mit exogener ALS führt hingegen zur Elimination auch der übrigen Porphyrine aus den Organismen, wobei die höher carboxylierten zu 78–99% in die Kulturflüssigkeit übergehen und Protoporphyrin noch zu über 75% in den Zellen verbleibt.

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This work was supported by grants from the Deutsche Forschungs-gemeinschaft.