Sister chromatid exchange

About: Sister chromatid exchange is a research topic. Over the lifetime, 3187 publications have been published within this topic receiving 90029 citations. The topic is also known as: replication-born DSB repair by SCE & GO:1990414.

Sister chromatid exchange and chromosome organization based on a bromodeoxyuridine Giemsa-C-banding technique (TC-banding).

Abstract: Hoechst 33258 fluorescent staining of bromodeoxyuridine substituted chromosomes provided a high resolution technique for following the segregation of replicated chromosomal DNA (Latt, 1973) Modifications have produced the same results after Giemsa staining (Wolff and Perry, 1975) Since this does not necessarily require Hoechst (Korenberg and Freedlander, 1975), we call this bromodeoxyuridine-Giemsa banding (BG-banding) We here describe a further modification which allows one to follow the T-rich strand of the AT-rich satellite DNA of C-band heterochromatin We call this TC-banding This technique was used to examine metacentric marker chromosomes found in mouse L-cells that contain many interstitial blocks of centromeric-type heterochromatin in each arm plus the usual two blocks of centromeric heterochromatin One of the advantages of this technique for such chromosomes is that it is possible to distinguish first from second cell cycle sister chromatid exchange and unambiguously detect centromeric sister chromatid exchange We found some chromosomes to have high rates of centromeric sister chromatid exchange After one cycle in bromodeoxyuridine we could examine the satellite polarity of the heterochromatic DNA Since there was no change in satellite polarity in any of the heterochromatic blocks, marker chromosomes could not have been formed by paracentric inversions, inverted insertions or inverted translocations These results allow the formulation of several rules of chromosome organization

The analysis of exchanges in tritium-labelled meiotic chromosomes: II. Stethophyma grossum

Abstract: The autoradiographic analysis of exchanges in tritium-labelled meiotic chromosomes is potentially a useful approach to the study of meiotic exchange events since this method differentially labels meiotic chromatids along their entire length. The main problem encountered in earlier autoradiographic studies is that of distinguishing label exchanges generated at chiasmata from label exchanges generated by sister chromatid exchange. This problem was overcome in the present study by the choice of a meiotic system (male meiosis of Stethophyma grossum) where chiasmata are limited to just one proximally localised chiasma in each bivalent. This system allows the positive identification of chiasma-generated label exchanges and demonstrates convincingly the origin of chiasmata through breakage and rejoining of homologous non-sister chromatids. Sister chromatid exchanges are also readily detected in labelled meiotic chromosomes of this species, where they occur with a mean frequency of 0.35 per chromosome. This frequency is similar to that found in mitotic spermatogonial cells and the exchanges are randomly distributed both within and between chromosomes. These features of meiotic sister chromatid exchanges suggest that they are unrelated to non-sister chiasmatic exchanges and they probably have no special meiotic significance.

Chromosome Aberrations in Psoriatic Patients Treated With Arsenic

Abstract: A significantly increased frequency of chromosomal aberrations was found in lymphocytes from eight psoriatic patients previously treated with arsenic than in lymphocytes from eight psoriatics with no such previous treatment. In most patients the arsenic therapy was discontinued more than 15 years ago. In the arsenic-treated group a statistically significant heterogeneity was found with respect to the frequency of aberrations. The frequency of sister chromatid exchange was not increased in the arsenic-treated patients.

Deceleration of carcinogenic potential by adaptation with low dose gamma irradiation.

Abstract: Animals that have been exposed to a very low dose of radiation are known to have many physiological benefits. Very low dose of ionizing radiation also induces mechanisms whereby cell or tissue become better fit to cope with subsequent exposures of high doses. This phenomenon of low dose radiation is termed 'adaptive response'. This response has been reported to be true in many biological systems and confirmed by experiments on chromosomal and chromatid aberrations, micronucleus formation, sister chromatid exchange tests, DNA mutation and cell survival study and using many other biological end points, although there are quite a few exceptions. The adaptation induced by low doses of radiation has been attributed to the induction of an efficient chromosome break repair mechanism at molecular and biochemical level. It is also substantiated in whole animal systems. When mice are initially conditioned with very small adapting doses, incidence of a challenging dose induced thymic lymphoma is recorded, with delayed latency and reduced frequency. Similarly, appearance of a transplanted barcl-95 thymic tumor has been delayed when mice are preconditioned with a small dose of radiation. Appearance and development of a tumour following transplantation of in vitro irradiated barcl-95 tumour cells with a small dose of 1 cGy are also delayed and volume of the tumour is reduced. Latency period of radiation-induced leukemia is modified by prior treatment with an adapting dose of radiation. Neoplastic transformation of several human cultured cells is also significantly decreased by prior low dose exposure of radiation compared to non-exposed cells. These results indicate that an earlier exposure to a small dose of radiation also reduces the radiation-induced carcinogenesis. Various aspects of molecular mechanism underlying the radio-adaptation have been explained. However, the mechanism underlying the inhibition of carcinogenesis by low dose radiation is yet to be fully resolved.

Antineoplastic and cytogenetic effects of platinum(II) and palladium(II) complexes with pyridine-2-carboxyaldehyde-thiosemicarbazone.

Abstract: The effect of six novel complexes of Pt(II) and Pd(II) with pyridine-2-carboxyaldehyde thiosemicarbazone (HPyTsc) on sister chromatid exchange rate and human lymphocyte proliferation kinetic was studi