China
Africa
Explore chapters and articles related to this topic
Recombinant DNA Technology
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2020
The centromeric function improves in YACs of 50 kb or more. YACs of 150 kb or more behave like regular yeast chromosomes. YACs are the predominant vector system used for cloning of very large (up to 100–1400 kb) DNA segments for mapping of complex eukaryotic chromosomes. YACs are reported to suffer from many problems, including chimerism, tedious steps in YAC library construction, and low yields of YAC insert DNA. The yeast genes present in different yeast vectors can become integrated into the host genome. This is called permanent transformation. It generally occurs through homologous recombination between the gene present in a vector (e.g., LEU2) and that present in the yeast chromosomes (e.g., LEU2). Rarely, the gene may become inserted at a random chromosome site. The homologous recombination may occur by regular crossing over or it may involve gene conversion (a nonreciprocal recombination).
Immune Reconstitution after Hematopoietic Stem Cell Transplantation
Published in Richard K. Burt, Alberto M. Marmont, Stem Cell Therapy for Autoimmune Disease, 2019
Andreas Thiel, Tobias Alexander, Christian A. Schmidt, Falk Hiepe, Renate Arnold, Andreas Radbruch, Larissa Verda, Richard K. Burt
B cells undergo further affinity maturation within lymph node germinal centers by a process of somatic hypermutation (SHM), gene conversion, and class switching recombination (CSR) (Fig. 4). SHM is the term for insertion of point mutations in the vicinity of the variable region exon (Fig. 4) and results in generation of antigen specific high affinity antibodies. Gene conversion is the transfer of a pseudovariable (ipV)gene sequence into the variable region exon (Fig. 4). Both SHM and gene conversion alters the antigen binding site of the immunoglobulin.71-72 CSR involves switching the constant region heavy change (e.g., IgM to IgG) that alters the effector function of the antibody (Fig. 4). The mechanisms involved in DNA SHM, gene conversion, and CSR although incompletely understood probably involve common mechanisms of DNA recognition, targeting, cleavage, and repair.73 The enzyme activation-induced cytidine deaminase (AID) is involved in all three reactions by helping to create the DNA cut or cleavage.65,74-75
Recombinant DNA technology
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2018
The centromeric function improves in YACs of 50 kb or more. YACs of 150 kb or more behave like regular yeast chromosomes. YACs are the predominant vector system used for cloning of very large (up to 100–1400 kb) DNA segments for mapping of complex eukaryotic chromosomes. YACs are reported to suffer from many problems, including chimerism, tedious steps in YAC library construction, and low yields of YAC insert DNA. The yeast genes present in different yeast vectors can become integrated into the host genome. This is called permanent transformation. It generally occurs through homologous recombination between the gene present in a vector (e.g., LEU2) and that present in the yeast chromosomes (e.g., LEU2—). Rarely, the gene may become inserted at a random chromosome site. The homologous recombination may occur by regular crossing over or it may involve gene conversion (a nonreciprocal recombination).
Modulating effect of DL-kavain on the mutagenicity and carcinogenicity induced by doxorubicin in Drosophila melanogaster
Published in Journal of Toxicology and Environmental Health, Part A, 2021
Thaís Teixeira da Silva, Júlia Braga Martins, Maria Do Socorro de Brito Lopes, Pedro Marcos de Almeida, José Luiz Silva Sá, Francielle Alline Martins
Carcinogenicity is often associated with homologous recombination. Although homologous recombination is an important DNA repair mechanism, there is growing evidence that it induces deleterious genomic rearrangements (Orsolin, Oliveira, and Nepomuceno 2012). Homologous recombination might also induce events such as gene conversion, deletion of chromosomal segments and translocations and it is also one of the main factors in the origin and progression of carcinogenic processes (Véras et al. 2020).