Deletion mapping was employed to determine the physical order of five morphological variants, pydl, yg2, wdl, u28 and u31, with respect to restriction fragment length polymorphism (RFLP) markers located at the distal end of chromosome 9s in maize. The genetic materials used were a series of terminaldeficiency mutants, newly derived with MCCLINTOCK’S original stocks developed in the 1940s, via b...

The frequency of sister chromatid exchange (SCE) has been followed sequentially after the addition of SV40 to human diploid fibroblast cultures. The SCE frequency was nearly the same in uninfected controls and in infected cultures before they became tumor antigen positive. When cells exhibited tumor antigen, the SCE frequency increased over a wide range, and changes in chromosome number and str...

Two aminoanthraquinone analogs 1,4-bis(2-[(2-hydroxyethyl)amino]ethylamino)-9,10-anthracenedione (HAQ) and 1,4-dihydroxy-5,8-bis(2-[(2-hydroxyethyl)amino]ethylamino]-9,10-anthracenedione (DHAQ) have been shown to possess similar therapeutic activities against experimental tumors but different toxicities to the animals. In this study, the genotoxic effects of these two drugs and a new analog, 1...

ONVENTIONAL recombination theory has held that genetic recombination occurs after DNA replication, when each chromosome is composed of two chromatids; that crossing over involves a full-chromatid interaction between nonsister chromatids, and yields reciprocal products from breakage reunion events; and that either no crossing over occurs between sister chromatids, or if it occurs it is unrelated...

Mutations in the human ChlR1 gene are associated with a unique genetic disorder known as Warsaw breakage syndrome characterized by cellular defects in sister chromatid cohesion and hypersensitivity to agents that induce replication stress. A role of ChlR1 helicase in sister chromatid cohesion was first evidenced by studies of the yeast homolog Chl1p; however, its cellular functions in DNA metab...

individuals handling antineoplastic drugs or their wastes may absorb these potent genotoxic agents. the effects of handling antineoplastic drugs were examined in a group of 24 nurses working in the hematology and oncology departments of two different university hospitals in shiraz (iran) and in a group of 18 unexposed nurses as control group. the cytogenetic repercussions of exposure were asses...

Breakage-fusion-bridge (BFB) cycle is a series of chromosome breaks and duplications that could lead to the increased copy number of a genomic segment (gene amplification). A critical step of BFB cycles leading to gene amplification is a palindromic fusion of sister chromatids following the rupture of a dicentric chromosome during mitosis. It is currently unknown how sister chromatid fusion is ...

Cytogenetic assays in peripheral blood lymphocytes (PBL) have been used extensively to survey the exposure of humans to genotoxic agents. The conceptual basis for this has been the hypothesis that the extent of genetic damage in PBL reflects critical events for carcinogenic processes in target tissues. Until now, no follow-up studies have been performed to assess the predictive value of these m...

Cyclophosphamide, an extensively used cancer chemotherapeutic agent, requires metabolic activation through a mixed-function oxygenase system. The capacity of this agent to produce oncogenic transformation and chromosomal damage, including increases in sister chromatid exchanges, was investigated in cell culture with or without an exogenous liver metabolic activation system. No oncogenic transfo...

The conserved family of cohesin proteins that mediate sister chromatid cohesion requires Scc2, Scc4 for chromatin-association and Eco1/Ctf7 for conversion to a tethering competent state. A popular model, based on the notion that cohesins form huge ring-like structures, is that Scc2, Scc4 function is essential only during G1 such that sister chromatid cohesion results simply from DNA replisome p...