The exchanges between sister chromatids were detected with the fluorescence plus Giemsa technique, in which the thymine analogue, bromodeoxyuridine, was used for DNA labelling. This method was used to examine the influence of bovine leukaemia virus on chromosomal disorders in bovine blood lymphocytes. In metaphasal chromosomes of BLV infected lymphocytes, numerous sister chromatid exchanges (SC...

The frequency of sister chromatid exchange (SCE) was determined in rat fibroblasts transformed by wild-type polyoma virus or by a mutant temperature sensitive for viral large tumor antigen function (ts-a). Elevated SCE frequencies were observed in two wild-type transformed cell lines growing at 37 degrees and in four ts-a-transformed lines upon growth at the permissive temperature for large vir...

To investigate the risks of exposure to ethylene oxide (EO) at current permissible levels and at past higher levels, an inception cohort of sterilizer operators and supervisors from the Central Processing Department (CPD), respiratory therapists, and engineers exposed to EO were identified at the McMaster University Medical Centre. A comparison group from Nutrition Services (NUTR) were matched ...

The potential mutagenicity of isoflurane was investigated by the sister chromatid exchange (SCE) test using peripheral blood lymphocytes from patients before and after anaesthesia. Thirty patients, aged 18-59 yr (median 29.5 yr), were anaesthetized for minor orthopaedic operations with isoflurane and nitrous oxide in oxygen for 37-90 min (median 64 min). Venous blood samples were drawn before t...

The frequency of sister chromatid exchange (SCE) was analyzed in bone marrow cells of 16 patients with chronic myeloid leukemia. We have compared the SCE frequency in these patients, in both chronic and blastic phases of the dis ease, to that of normal individuals. The frequency of SCE in blastic-phase chronic myeloid leukemia patients (mean, 1.86/ cell) was significantly lower than that in chr...

In mammalian cells, one of the most sensitive indicators of exposure to mutagenic carcinogens has been the induction of cytogenetic effects, chromosome aberrations and sister chromatid exchanges (SCEs). Some mutagens, such as ionizing radiations that induce double-strand breaks in DNA are very efficient at inducing chromosome aberrations and can induce them at all stages of the cell cycle. Some...

Rev1 is a deoxycytidyl transferase associated with DNA translesion synthesis (TLS). In addition to its catalytic domain, Rev1 possesses a so-called BRCA1 C-terminal (BRCT) domain. Here, we describe cells and mice containing a targeted deletion of this domain. Rev1(B/B) mice are healthy, fertile and display normal somatic hypermutation. Rev1(B/B) cells display an elevated spontaneous frequency o...

Reproductive failure of a number of fish-eating birds was observed on the Great Lakes in the mid-1960s to mid-1970s. The herring gull (Larus argentatus) has been used as the primary monitoring species. The low hatching success observed in this species on Lake Ontario in the mid-1970s was due to loss of eggs and failure of eggs to hatch. Egg exchange experiments demonstrated that this was due bo...

Sister chromatid cohesion is mediated by cohesin, whose Smc1, Smc3, and kleisin (Scc1) subunits form a ring structure that entraps sister DNAs. The ring is opened either by separase, which cleaves Scc1 during anaphase, or by a releasing activity involving Wapl, Scc3, and Pds5, which bind to Scc1 and open its interface with Smc3. We present crystal structures of Pds5 from the yeast L. thermotole...

Most mitotic homologous recombination (HR) events proceed via a synthesis-dependent strand annealing mechanism to avoid crossing over, which may give rise to chromosomal rearrangements and loss of heterozygosity. The molecular mechanisms controlling HR sub-pathway choice are poorly understood. Here, we show that human RECQ5, a DNA helicase that can disrupt RAD51 nucleoprotein filaments, promote...