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The laboratory basis of medical genetics
Published in Peter S. Harper, The Evolution of Medical Genetics, 2019
Following the development of chromosome banding, a later technique that would help to bridge cytogenetics and human molecular genetics was in situ hybridization, initially using autoradiography to detect radioactive probes for repetitive DNA sequences, by Pardue and Gall (1970) in America, then progressively refined to detect single copy sequences, using fluorescent rather than radioactive labels. Multiple probes allowed ‘chromosome painting’, pioneered by Malcolm Ferguson-Smith and colleagues, by now based in Cambridge; this proved especially useful in comparative cytogenetic studies of different species, where patterns of chromosome segment rearrangement could often indicate their evolutionary lineage. Ferguson-Smith (2015) has outlined the successive developments in this transition period.
A Survey of Newer Gene Probing Techniques
Published in Victor A. Bernstam, Pocket Guide to GENE LEVEL DIAGNOSTICS in Clinical Practice, 2019
In general, the competitive hybridization approach is used to enhance the specificity in detecting target sequences. “Chromosome painting’’ uses large pools of cloned genomic sequences from a single human chromosome as probe and, by performing a preannealing step in the presence of an excess of sonicated total human DNA, complete staining of a given chromosome can be achieved in metaphase and interphase nuclei. When applied to tissues, CISH can be helpful in reducing the contribution of the signal from repetitive DNA through the addition of competitor DNA, by analogy with the technique used in Southern hybridizations. A marked increase in the ratio of specific to nonspecific hybridization signal can be achieved under optimal preannealing conditions.
In Situ Hybridization
Published in Attila Lorincz, Nucleic Acid Testing for Human Disease, 2016
Multicolor FISH assays are indispensable for obtaining precise descriptions of complex chromosomal rearrangements. Routine application of such techniques to human chromosomes started in 1996 with the simultaneous use of all 24 human whole-chromosome painting probes in multiplex-FISH and spectral karyotyping (SKY). Since then, different approaches for chromosomal differentiation based on multicolor-FISH assays have been described,136 predominantly to characterize marker chromosomes identified in conventional banding analysis. Their characterization is of high clinical impact and is the requisite condition for further molecular investigations aimed at the identification of disease-related genes.
Acrylonitrile’s genotoxicity profile: mutagenicity in search of an underlying molecular mechanism
Published in Critical Reviews in Toxicology, 2023
Richard J. Albertini, Christopher R. Kirman, Dale E. Strother
ACN’s potential for inducing numerical chromosome aberrations, i.e. aneuploidy, is suggested by a single Drosophila study of sex-linked chromosomes. The human study with its several deficiencies also claims to have found sex-linked aneuploidy in ACN-exposed workers. Also, the cytogenetic study that reported an increase in chromosome aberrations in ACN-exposed mice included a class of meiotic changes that theoretically could result in aneuploidy, although no numerical chromosome changes were observed. These findings in the existing data base could all be addressed in a repeat cytogenetic study. Cytogenetic analyses of male germ cells, i.e. spermatogonia, spermatocytes and early spermatids, is a well-established method for detecting both structural and numerical chromosome aberrations in rodents (Allen et al. 1986; Adler et al. 2012; Yauk et al. 2015; OECD Guideline 483, 2016). Chromosome painting can add to the precision of the analysis. Micronuclei may also be measured in spermatids (Adler et al. 2012). An add-on to the proposed cytogenetic studies that may at least suggest transmission of numerical chromosome aberrations would be FISH analysis of mature sperm using sex-chromosome centromere probes.
Multifaceted applications of pre-mature chromosome condensation in radiation biodosimetry
Published in International Journal of Radiation Biology, 2020
Usha Yadav, Nagesh Nagabhushana Bhat, Kapil Bansidhar Shirsath, Utkarsha Sagar Mungse, Balvinder Kaur Sapra
Many laboratories use a cocktail DNA probes for detecting translocations in three pairs of chromosomes that comprise at least 20% of the human. Whole chromosome painting allows identification of chromosome specific fragments, translocations, and insertions involving painted chromosomes. We have tested the feasibility of detecting radiation induced chromosomal aberrations using the whole chromosome paints (Chr# 1, 2 and 4) on G0-PCCs prepared from mock and gamma rays irradiated lymphocytes (Figure 3(c)). PCCs prepared from mock treated cells showed two intact signals for each of the chromosome pairs while aberrant PCC spreads from irradiated cells showed more than 6 signals resulting from all types of chromosomal aberrations: fragments, translocations and insertions.