细胞技术

Spermatogenesis is a continuous, highly organized process comprised of sequential steps of cell proliferation and differentiation (1). In male mammals, spermatogenesis proceeds for the reproductive lifetime of the animals. The continuation of this process depends on a pool of spe ...

Spermatogenesis is a complex, well-organized process including proliferation, differentiation, apoptosis, and morphogenesis through which differentiating daughter cells of spermatogonial stem cells develop into mature sperm (1,2). In men, this process requires approx ...

Transcription-coupled repair (TCR) is a sub-pathway of nucleotide excision repair that allows for the enhanced repair of the transcribed strand of active genes. A classical method to study DNA repair in vivo consists in the molecular analysis of UV-induced DNA damages at specific loci. Cells ...

Phosphorylation of histone H2AX on Ser 139 is a sensitive reporter of DNA damage, particularly if the damage involves induction of DNA double-strand breaks (DSBs). Phosphorylated H2AX has been named γH2AX and its presence in the nucleus can be detected immunocytochemically. Multipara ...

The comet assay is a simple gel electrophoresis method for visualizing and quantifying DNA damage. The comet assay is sensitive and reproducible and can be used to detect single-strand DNA breaks, double-strand DNA breaks, protein-associated DNA strand breaks and DNA crosslinks. The com ...

Comparative genomic hybridization (CGH) allows the global screening of copy number aberrations within a sample. Specifically, large (20 mb) deletions and amplifications are detected, which are likely to indicate regions harboring tumor suppressor and oncogenes. CGH involves the ...

Regulatory mechanisms for DNA replication are crucial to the control of the cell cycle in eukaryotic cells. One of the widely used assays to understand the complex mammalian replication system is the cell-free in vitro replication assay (IVRA). IVRA can provide a snapshot of the regulatory mec ...

Epigenetic modification plays a central role in the regulation of gene expression and therefore in the development of disease states. In particular, genomic methylation of cytosines within CpG dinucleotides is crucial to development, gene silencing and chromosome inactivation. ...

Histone methylation plays important roles in chromatin structure, transcription, and epigenetic state of the cell. Tremendous discoveries recently demonstrated that methylation mark is not static but is dynamically regulated by both histone methyltransferases and the his ...

Protein arginine methylation has emerged as an important mechanism for regulating the functions of proteins involved in diverse aspects of gene regulation such as transcriptional activation and repression, mRNA processing and nuclear-cytoplasmic shuttling. This modific ...

Histone chaperones are a group of histone-interacting proteins, involved in several important cellular functions. These chaperones are essential to facilitate ordered assembly of nucleosomes, both in replication dependent and independent manner. Replication independ ...

Histone deacetylases (HDACs) are enzymes that catalyze the removal of acetyl groups from the ɛ-amino groups of conserved lysine residues in the amino terminal tail of histones. In humans, there are 18 potential deacetylase enzymes that are responsible for the removal of acetyl groups and mai ...

Posttranslational histone modifications play important roles in regulating chromatin structure and function (Martin and Zhang, Nat Rev Mol Cell Biol 6:838–849, 2005; Jenuwein and Allis, Science 293:1074–1080, 2001). One example of such modifications is histone ubiquitination, w ...

A rigorous biochemical analysis of chromatin structure and function requires the assembly of chromatin in vitro. A useful alternative to reconstituting nucleosomal arrays from pure or recombinant histones by salt gradient dialysis is the assembly of more complex chromatin from as ...

Growth factor stimulation results in phosphorylation of histone H3 at ser 10 and this correlated with expression of immediate early genes suggesting that this phosphorylation is associated with transcriptional activation. Although Western immunoblot analysis allows the de ...

Studies in the past decade have shown that differential gene expression depends not only on the binding of specific transcription factors to discrete promoter elements but also on the epigenetic modification of the DNA as well as histones associated with the promoter. While techniques li ...

Deregulation of transcriptional activity of many genes has been causatively linked to human diseases including cancer. Altered patterns of gene expression in normal and cancer cells are the result of inappropriate expression of transcription factors and chromatin-modifying p ...

ChIP-Chip microarray data analysis is a multi-step approach that requires several different applications to progress from the initial stages of raw data analysis to the identification and characterization of ChIP-binding sites. There are multiple approaches to data analysis and s ...

The telomeric repeat amplification protocol (TRAP) assay is a highly sensitive PCR based assay and is an important tool for understanding the role of telomerase in cancer. This assay measures an enzymatic activity where the amount of target is dependent upon the activity of the enzyme. This pro ...

The ataxia telangiectasia-mutated gene product (ATM), whose loss of function is responsible for ataxia telangiectasia (A-T), is a protein kinase that interacts with several substrates and is implicated in mitogenic signal transduction, chromosome condensation, meiotic recom ...