微生物学技术

In the nucleus of eukaryotic cells, DNA is packaged into a nucleoprotein complex known as chromatin (1). This complex provides the compaction and structural organization of the DNA for processes such as replication, transcription, recombination, and repair. The highly compact struct ...

The majority of DNA in eukaryotic cells is packaged by histones and many poorly characterized nonhistone proteins to form a dynamic structure known as chromatin. Chromatin is a periodic structure made up of repeating, regularly spaced subunits, the nucleosomes. Elegant genetic experi ...

Specific acetylation at conserved lysines in the N-terminal tails of histones have been correlated with distinct chromatin structures, association of specific chromatin proteins, accessibility of nucleosomal DNA toward interaction of transcription factors, and unfolded ...

The value of a solid support was recognized early in history by the ancient Greek engineer Archimedes who, amazed by the power of the leverage machines that he invented, exclaimed that he could even move the entire planet had he only a suitable solid support to rely on. In biochemistry, sophisticated mu ...

Cell division in eukaryotes follows an extremely complex plan according to which chromosomes are first duplicated and condensed more than 10,000 times to form the mitotic chromosomes, which are finally separated by the cellular machinery into two new nuclei. Although the fascinating p ...

The packaging of DNA into a chromatin structure within the eukaryotic nucleus can affect processes such as DNA replication, transcription, recombination and repair. During nucleotide excision repair (NER), a major DNA repair pathway, rearrangements of the nucleosomal organisat ...

Folding of DNA into nucleosomes and higher order chromatin structures restricts its accessibility to proteins and drugs. Hence, the location of histone octamers on the DNA sequence (nucleosome positions) as well as structural and dynamic properties of nucleosomes may play important ...

An ideal biochemical source of a defined chromatin template assembled in vivo is the SV40 minichromosomes (see Note 1). At all stages in the viral lytic cycle, SV40 DNA is complexed with cellular histone and nonhistone proteins to form the episomal chromatin structure called a minichromosome ...

In vitro studies on nucleosome core particles (NCPs) and nucleosomes have generally been limited to the use of histone proteins isolated from chromatin. Numerous reliable and well-established methods have been described of obtaining single histone proteins in significant quant ...

In chromatin, each nucleosome contains two specific binding sites for nonhistone chromosomal proteins HMG-14 or HMG-17; however, because the amount of these proteins in the nucleus is limited, only a small fraction of the nucleosomes contain these proteins. A central question on the role of H ...

Eukaryotic genome replication implies that both the DNA and the associated proteins must be duplicated during each S phase. Model systems such as the simian virus 40 (SV40) in vitro replication system have provided important information on the mechanism of DNA replication in mammalian cel ...

In vivo DNA is associated with the proteins that constitute chromatin. This means that, any process that requires access to the genetic material must do so within the context of chromatin. It is now clear that there is a complex cellular machinery dedicated to regulating chromatin structure and t ...

Histones are the predominant protein component of chromatin and are subject to a variety of post-translational modifications. Of these, acetylation of the amino-terminal tails of core histones is most intensively studied and is linked to chromatin assembly, the regulation of gene exp ...

A central problem in the control of eukaryotic gene expression is how the compaction of DNA in chromatin is overcome to allow the initiation and elongation of transcription (1–6). Current studies reveal that multiple mechanisms are involved in counteracting chromatin-mediated repre ...

Treatment of nuclei with limited amounts of DNaseI can be used to reveal sites in chromatin that are hypersensitive (HS) to the nuclease (1,2). DNaseI HS sites are thought to correspond to sites where the regular nucleosome structure is perturbed, e.g., by binding of proteins to chromatin such that DNA ...

Posttranslational acetylation of the core histone amino-terminal tails correlates with both chromatin assembly and gene expression. This energy-intensive and reversible process is mediated by the opposing activities of histone acetyltransferase (HAT) and deacetylase ( ...

The structural and functional subunits of chromatin are nucleosome cores. In a nucleosome core 145 bp of DNA are coiled around the outer surface of an octamer of histone proteins which consists of a tetramer of 2(H3�H4) and two H2A�H2B dimers (1). DNA extending from the nucleosome core to the next nucleo ...

This chapter addresses the application of ribozymes in studying an important area of cancer biology, the process of metastasis. An example is given on how ribozymes can be used to study the role in this process of one particular gene. Initially, a brief introduction to the biology of cancer metastas ...

Inflammation and tissue injury are characterized by a massive infiltration of mononuclear cells responsible for the production of a variety of cytokines that alter the biosynthetic repertoire of the connective tissue cells (1,2). Recently, experiments in animal models of autoimmu ...

The use of oligodeoxynucleotides (ODN) to disrupt gene function has been studied in a variety of in vitro and in vivo systems (1–14). Antigene, antisense, ribozyme, and aptamer nucleic acid molecules have been shown in numerous model systems to effect DNA, RNA, or protein targets, or physiologic pr ...