细胞技术

Spliceosomes are multicomponent enzymes that remove introns from premessenger RNAs (pre-mRNAs) (1–3) in the reaction known as pre-mRNA splicing. Spliceosomes are ribonucleoprotein (RNP) machines consisting of both RNA and protein components. SnRNPs, composed of small nuclear ...

Splicing of eukaryotic precursor messenger RNAs (pre-mRNAs) excises the intron from the precursor and ligates the two exons together to produce the mature mRNA. It occurs via a two-step mechanism (Fig. 1) (reviewed in ref. 1). In the first step the 2′ hydroxyl group of an intronic adenylyl residue init ...

Splicing reactions are typically carried out using nuclear extracts, S100 extracts complemented with SR proteins, or partially purified fractions derived from the crude extracts. The extract preparation procedures are described in Chapter 24. Extracts derived from HeLa cells are ...

Following the initial discovery of split genes in 1977, it took several years before in vitro systems were successfully developed to study the biochemistry of pre-mRNA splicing. The first systems relied on coupling of transcription and splicing in whole-cell extracts and were fairly inef ...

Iterative selection strategies have been widely used to enrich specific RNA molecules from randomized pools based on binding affinities or an RNA-mediated activity (6,8). The vast majority of these procedures have been performed in cell-free systems. Of particular use would be iterati ...

Meiotic recombination is triggered by programmed DNA double-strand breaks (DSBs), which are catalyzed by Spo11 protein in a type II topoisomerase-like manner. Meiotic DSBs can be detected directly using physical assays (gel electrophoresis, Southern blotting, and indirect end-l ...

Traditional methods for surveying meiotic recombination in humans are limited to pedigree and linkage disequilibrium analyses. We have developed assays that allow the direct detection of crossover and gene conversion molecules in batches of sperm DNA. To date, we have characterized ...

The recombination between homologous chromosomes during the prophase of the first meiotic division plays an essential role in the formation of euploid gametes, as well as contributing to genetic diversity through the generation of new allele combinations. Two types of products are for ...

Cooperative actions of chromosomal proteins play critical roles in the dynamics, structural transition, segregation, and maintenance of meiotic chromosomes. A high-resolution genome-tiling array combined with a chromatin immunoprecipitation assay (ChIP-chip) is a powe ...

During meiotic prophase a number of important events require recombination between maternal and paternal chromosomes, which is initiated through the introduction of DNA double-strand breaks (DSBs). The majority of DSBs, which mostly occur at so-called hotspots, have been located b ...

One of the major features of meiosis is a high frequency of homologous recombination that not only confers genetic diversity to a successive generation but also ensures proper segregation of chromosomes. Meiotic recombination is initiated by DNA double-strand breaks that require many ...

The fission yeast Schizosaccharomyces pombe has many biological characteristics that make it an ideal model organism for the study of meiosis. A nearly synchronous meiosis is one of the most important. Under certain environmental and genetic conditions, large cultures of S. pombe can be in ...

Joint Molecule (JM) recombination intermediates result from DNA strand-exchange between homologous chromosomes. Physical monitoring of JM formation in budding yeast has provided a wealth of information about the timing and mechanism of meiotic recombination. These assays are ...

The SPO11 protein generates programmed DNA double-strand breaks (DSBs) that initiate meiotic recombination. Endonucleolytic cleavage 3′ to the DSB sites releases SPO11 from DNA, leaving SPO11 covalently associated with an oligonucleotide. This chapter describes detection of ...

During meiosis Spo11 catalyzes the formation of DNA double-strand breaks, becoming covalently attached to the 5′ ends on both sides of the break during this process. Spo11 is removed from the DSB by single-stranded endonucleolytic cleavage flanking the DSB, liberating a short-lived spec ...

DNA double-strand breaks (DSBs) initiate meiotic recombination in eukaryotes. We describe two strategies that use microarrays to determine the genome-wide distribution of meiotic DSBs in the yeast Saccharomyces cerevisiae. The first is a chromatin immunoprecipitation (ChIP) ...

The study of location and intensity of double-strand breaks (DSBs) in mammalian systems is more challenging than in yeast because, unlike yeast, the progression through meiosis is not synchronous and only a small fraction of all testis cells are actually at the stage where DSB formation is initi ...

Measuring meiotic gene conversion is important both because of its role in the fundamental mechanisms of meiotic recombination and because of its influence on linkage relationships and allelic diversity in the genome. Historically, gene conversion has been most thoroughly examin ...

Caenorhabditis elegans is an important experimental organism for the study of recombination during meiosis. A variety of techniques have been developed for the measurement of meiotic recombination in C. elegans, ranging from traditional genetic measures to direct cytological d ...

The fission yeast Schizosaccharomyces pombe is well-suited for studying meiotic recombination. Methods are described here for culturing S. pombe and for genetic assays of intragenic recombination (gene conversion), intergenic recombination (crossing-over), and spore via ...