A new method for determining nucleotide sequences in DNA is described. It is similar to the “plus and minus” method [Sanger, F. & Coulson, A. R. (1975) J. Mol. Biol. 94, 441-448] but makes use of the 2′,3′-dideoxy and arabinonucleoside analogues of the normal deoxynucleoside triphosphates, which act as specific chain-terminating inhibitors of DNA polymerase. The technique has been applied to the DNA of bacteriophage ϕX174 and is more rapid and more accurate than either the plus or the minus method.

/pdf/dna-sequencing-with-chain-terminating-inhibitors-t64rmetxr4.pdf

DNA sequencing with chain-terminating inhibitors

Oligodendrocytes, the myelin-forming cells of the central nervous system (CNS), and astrocytes constitute macroglia. This review deals with the recent progress related to the origin and differentiation of the oligodendrocytes, their relationships to other neural cells, and functional neuroglial interactions under physiological conditions and in demyelinating diseases. One of the problems in studies of the CNS is to find components, i.e., markers, for the identification of the different cells, in intact tissues or cultures. In recent years, specific biochemical, immunological, and molecular markers have been identified. Many components specific to differentiating oligodendrocytes and to myelin are now available to aid their study. Transgenic mice and spontaneous mutants have led to a better understanding of the targets of specific dys- or demyelinating diseases. The best examples are the studies concerning the effects of the mutations affecting the most abundant protein in the central nervous myelin, the p...

/pdf/biology-of-oligodendrocyte-and-myelin-in-the-mammalian-3ggbjcby4w.pdf

Biology of Oligodendrocyte and Myelin in the Mammalian Central Nervous System

Improvements in genomic and molecular methods are expanding the range of potential applications for circulating tumour DNA (ctDNA), both in a research setting and as a 'liquid biopsy' for cancer management. Proof-of-principle studies have demonstrated the translational potential of ctDNA for prognostication, molecular profiling and monitoring. The field is now in an exciting transitional period in which ctDNA analysis is beginning to be applied clinically, although there is still much to learn about the biology of cell-free DNA. This is an opportune time to appraise potential approaches to ctDNA analysis, and to consider their applications in personalized oncology and in cancer research.

/pdf/liquid-biopsies-come-of-age-towards-implementation-of-3ovu7jzn3f.pdf

Liquid biopsies come of age: towards implementation of circulating tumour DNA

Thousands of loci in the human and mouse genomes give rise to circular RNA transcripts; at many of these loci, the predominant RNA isoform is a circle. Using an improved computational approach for circular RNA identification, we found widespread circular RNA expression in Drosophila melanogaster and estimate that in humans, circular RNA may account for 1% as many molecules as poly(A) RNA. Analysis of data from the ENCODE consortium revealed that the repertoire of genes expressing circular RNA, the ratio of circular to linear transcripts for each gene, and even the pattern of splice isoforms of circular RNAs from each gene were cell-type specific. These results suggest that biogenesis of circular RNA is an integral, conserved, and regulated feature of the gene expression program.

/pdf/cell-type-specific-features-of-circular-rna-expression-4ao4gawmcm.pdf

Cell-type specific features of circular RNA expression.

Post-transcriptional gene regulation (PTGR) concerns processes involved in the maturation, transport, stability and translation of coding and non-coding RNAs. RNA-binding proteins (RBPs) and ribonucleoproteins coordinate RNA processing and PTGR. The introduction of large-scale quantitative methods, such as next-generation sequencing and modern protein mass spectrometry, has renewed interest in the investigation of PTGR and the protein factors involved at a systems-biology level. Here, we present a census of 1,542 manually curated RBPs that we have analysed for their interactions with different classes of RNA, their evolutionary conservation, their abundance and their tissue-specific expression. Our analysis is a critical step towards the comprehensive characterization of proteins involved in human RNA metabolism.

/pdf/a-census-of-human-rna-binding-proteins-1mii7pfs5y.pdf

A census of human RNA-binding proteins.

Acetylation regulates the stability of a bacterial protein: growth stage-dependent modification of RNase R.

Ribonucleases (RNases) are mediators in most reactions of RNA metabolism. In recent years, there has been a surge of new information about RNases and the roles they play in cell physiology....

Bacterial ribonucleases and their roles in RNA metabolism

Proteins are fragile molecules that often require great care during purification to ensure that they remain intact and fully active. Nowadays, many proteins are also purified in small amounts under denaturing conditions by various gel electrophoretic techniques, such that inactive proteins are obtained. But even here, it is usually advantageous to maintain the protein in an intact form. In the case of enzymes, and other proteins with assayable biological activities, maintenance of activity is generally of prime importance, both for following the protein during purification and for subsequent studies of function. This chapter will focus on the major points to keep in mind with regard to maintaining the stability of a protein during purification and storage. Various other chapters describe in detail stabilization procedures for specific biological systems and specific classes of proteins.

Maintaining protein stability.

An Important Role for the Multienzyme Aminoacyl-tRNA Synthetase Complex in Mammalian Translation and Cell Growth

Polyadenylation at the 3′ terminus has long been considered a specific feature of mRNA and a few other unstable RNA species. Here we show that stable RNAs in Escherichia coli can be polyadenylated as well. RNA molecules with poly(A) tails are the major products that accumulate for essentially all stable RNA precursors when RNA maturation is slowed because of the absence of processing exoribonucleases; poly(A) tails vary from one to seven residues in length. The polyadenylation process depends on the presence of poly(A) polymerase I. A stochastic competition between the exoribonucleases and poly(A) polymerase is proposed to explain the accumulation of polyadenylated RNAs. These data indicate that polyadenylation is not unique to mRNA, and its widespread occurrence suggests that it serves a more general function in RNA metabolism.

https://www.pnas.org/content/pnas/95/21/12158.full.pdf

Murray P. Deutscher

Papers

Acetylation regulates the stability of a bacterial protein: growth stage-dependent modification of RNase R.

Bacterial ribonucleases and their roles in RNA metabolism

Maintaining protein stability.

An Important Role for the Multienzyme Aminoacyl-tRNA Synthetase Complex in Mammalian Translation and Cell Growth

Polyadenylation of stable RNA precursors in vivo