HeterochromatinHeterochromatin is a tightly packed form of DNA or condensed DNA, which comes in multiple varieties. These varieties lie on a continuum between the two extremes of constitutive heterochromatin and facultative heterochromatin. Both play a role in the expression of genes. Because it is tightly packed, it was thought to be inaccessible to polymerases and therefore not transcribed; however, according to Volpe et al. (2002), and many other papers since, much of this DNA is in fact transcribed, but it is continuously turned over via RNA-induced transcriptional silencing (RITS).
Non-homologous end joiningNon-homologous end joining (NHEJ) is a pathway that repairs double-strand breaks in DNA. NHEJ is referred to as "non-homologous" because the break ends are directly ligated without the need for a homologous template, in contrast to homology directed repair (HDR), which requires a homologous sequence to guide repair. NHEJ is active in both non-dividing and proliferating cells, while HDR is not readily accessible in non-dividing cells. The term "non-homologous end joining" was coined in 1996 by Moore and Haber.
ImmunoelectrophoresisImmunoelectrophoresis is a general name for a number of biochemical methods for separation and characterization of proteins based on electrophoresis and reaction with antibodies. All variants of immunoelectrophoresis require immunoglobulins, also known as antibodies, reacting with the proteins to be separated or characterized. The methods were developed and used extensively during the second half of the 20th century.
Senescence-associated secretory phenotypeSenescence-associated secretory phenotype (SASP) is a phenotype associated with senescent cells wherein those cells secrete high levels of inflammatory cytokines, immune modulators, growth factors, and proteases. SASP may also consist of exosomes and ectosomes containing enzymes, microRNA, DNA fragments, chemokines, and other bioactive factors. Soluble urokinase plasminogen activator surface receptor is part of SASP, and has been used to identify senescent cells for senolytic therapy.
Yeast artificial chromosomeYeast artificial chromosomes (YACs) are genetically engineered chromosomes derived from the DNA of the yeast, Saccharomyces cerevisiae, which is then ligated into a bacterial plasmid. By inserting large fragments of DNA, from 100–1000 kb, the inserted sequences can be cloned and physically mapped using a process called chromosome walking. This is the process that was initially used for the Human Genome Project, however due to stability issues, YACs were abandoned for the use of Bacterial artificial chromosome The bakers' yeast S.
DNA polymerase betaDNA polymerase beta, also known as POLB, is an enzyme present in eukaryotes. In humans, it is encoded by the POLB gene. In eukaryotic cells, DNA polymerase beta (POLB) performs base excision repair (BER) required for DNA maintenance, replication, recombination, and drug resistance. The mitochondrial DNA of mammalian cells is constantly under attack from oxygen radicals released during ATP production. Mammalian cell mitochondria contain an efficient base excision repair system employing POLB that removes some frequent oxidative DNA damages.
Olney's lesionsOlney's lesions, also known as NMDA receptor antagonist neurotoxicity (NAT), is a form of brain damage observed in rats and certain other model animals exposed to large quantities of psychoactive drugs that inhibit the normal operation of the neuronal NMDA receptor. Such lesions are common in anesthesia, as well as certain psychiatric treatments. The visible signs of NAT are named after John Olney, who conducted a study in 1989 to investigate neurotoxicity caused by PCP and related drugs.
