Non-B DNA structure-induced genetic instability and evolution

Repetitive DNA motifs are abundant in the genomes of various species and have the capacity to adopt non-canonical (i.e., non-B) DNA structures. Several non-B DNA structures, including cruciforms, slipped structures, triplexes, G-quadruplexes, and Z-DNA, have been shown to cause mutations, such as deletions, expansions, and translocations in both prokaryotes and eukaryotes. Their distributions in genomes are not random and often co-localize with sites of chromosomal breakage associated with genetic diseases. Current genome-wide sequence analyses suggest that the genomic instabilities induced by non-B DNA structure-forming sequences not only result in predisposition to disease, but also contribute to rapid evolutionary changes, particularly in genes associated with development and regulatory functions. In this review, we describe the occurrence of non-B DNA-forming sequences in various species, the classes of genes enriched in non-B DNA-forming sequences, and recent mechanistic studies on DNA structure-induced genomic instability to highlight their importance in genomes.     

Inhibition by carbaryl of DNA,RNA and protein synthesis in cultured rat lung cells

Summary The carbamate pesticide carbaryl rapidly inhibited DNA, RNA and protein synthesis in L-2 cells from rat lung. the inhibiton was partly reversible and was not accompanied by inhibiton of transport of tritiated precursors into intracellular pools or destruction of the integrity of the cell membrane.We thank W. H. J. Douglas for his gift of L-2 cells.This work was supported by contract 22140 of the Kentucky Tobacco Research Board.     

The effect of plant growth substances and natural products on RNA and DNA synthesis in leukocytes

Summary The effect of auxins, cytokinins, gibbrellins and phenolics on the incorporation of uridine and thymidine into the nucleic acids of human leukocytes was examined. Both the stimulation and inhibition of the incorporation of the precursors was noted. The auxins consistently promoted the incorporation of uridine.     

The effect of plant growth substances and natural products on RNA and DNA synthesis in leukocytes.

The effect of auxins, cytokinins, gibberellins and phenolics on the incorporation of uridine and thymidine into the nucleic acids of human leukocytes was examined. Both the stimulation and inhibition of the incorporation of the precursors was noted. The auxins consistently promoted the incorporation of uridine.     

A kinetic model for nucleohistone-dependent DNA synthesis

Résumé A basse concentration de «template» et de déoxynucléoside triphosphate, la vitesse de synthèse de DNA par la DNA polymérase deE. coli suit la loi simple de Michaelis. Les valeurs deK _m et deV pour les réactions dépendant de la nucléohistone sont plus basses que les valeurs pour les réactions dépendant du DNA, mais les rapportsV/K _m sont semblables. Les additions supplémentaires de constituants du mélange réactionnel de la polymérase n'ont eu qu'un très faible effet sur le système dépendant de la nucléohistone.

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This work was conducted under a cooperative agreement between the Division of Biology, California Institute of Technology and the Western Utilization Research and Development Division, Agricultural Research Service, U.S. Department of Agriculture. The work was supported in part by U.S. Public Health Service Grants Nos. GM-03977, GM-05143, AM-03102.Reference to a company or product name does not imply approval or recommendation of the product by the U.S. Department of Agriculture to the exclusion of others that may be suitable.     

A method for revealing inhibition of virus-induced synthesis of RNA

Zusammenfassung In mit Actinomycin D behandelten und mit dem Pseudogeflügelpest-Virus (NDV) infizierten Zellen gelingt der Nachweis einer ausgesprochenen Phase der Virus-RNS-Synthese. Mit dieser Methode lässt sich ebenfalls die Wirkung verschiedener Präparate auf die Virusnukleinsäuresynthese erfassen.     

The structure and function of initiation factors in eukaryotic protein synthesis

Protein synthesis is one of the most complex cellular processes, involving numerous translation components that interact in multiple sequential steps. The most complex stage in protein synthesis is the initiation process. It involves initiation factor-mediated assembly of a 40S ribosomal subunit and initiator tRNA into a 48S initiation complex at the initiation codon of an mRNA and subsequent joining of a 60S ribosomal subunit to form a translationally active 80S ribosome. The basal set of factors required for translation initiation has been determined, and biochemical, genetic, and structural studies are now beginning to reveal details of their individual functions in this process. The mechanism of translation initiation has also been found to be influenced significantly by structural properties of the 5' and 3' termini of individual mRNAs. This review describes some of the major developments in elucidating molecular details of the mechanism of initiation that have occurred over the last decade.     

Liver DNA and RNA in patothenic acid deficiency

Riassunto È stato studiato nel ratto mantenuto a dieta carente di acido pantotenico l'effetto della somministrazione dietetica della vitamina sul contenuto ed il turnover degli acidi nucleinici del fegato. L'acido pantotenico non influenza il contenuto degli acidi nucleinici e l'incorporazione del P³² nel DNA, mentre provoca un aumento dell'incorporazione del P³² nell'RNA, interpretato come un'azione indiretta della vitamina.

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This investigation was supported by a grant from the CNR, Roma.     

α-Amanitin: its effect on RNA synthesis in polytene chromosomes

Zusammenfassung Autoradiographisch wurde festgestellt, dass -Amanitin in explantierten Speicheldrüsen vonChironomus-thummi-Larven die Synthese der chromosomalen RNA hemmt. Die nukleoläre RNA-Synthese bleibt unbeeinflusst. Behandlung der Larven für 22–24 h in einer wässrigen Amanitin-Lösung ergab bisher keinen spezifischen Effekt.