Neural ganglia of wild type third-instar larvae of Drosophila melanogaster were incubated for 13 hours at various concentrations of BUdR (1, 3, 9, 27 micrograms/ml). Metaphases were collected with colchicine, stained with Hoechst 33258, and scored under a fluorescence microscope. Metaphases in which the sister chromatids were clearly differentiated were scored for the presence of sister-chromat...

Inverted duplications are a common type of copy number variation (CNV) in germline and somatic genomes. Large duplications that include many genes can lead to both neurodevelopmental phenotypes in children and gene amplifications in tumors. There are several models for inverted duplication formation, most of which include a dicentric chromosome intermediate followed by breakage-fusion-bridge (B...

Previous analyses by fluorescence in situ hybridization of structures present 20-30 cell generations after the primary events of mammalian gene amplification have shown that tens of megabases of DNA separate each copy of the selected gene in chromosomal arrays that contain up to 15 copies. Since these structures are very unstable, it is necessary to study amplified DNA as soon as possible after...

Homologous chromosome synapsis ("homosynapsis") and crossing over are well-conserved aspects of meiotic chromosome behavior. The long-standing assumption that these two processes are causally related has been challenged recently by observations in Saccharomyces cerevisiae of significant levels of crossing over (1) between small sequences at nonhomologous locations and (2) in mutants where synap...

Combined cytogenetic, fluorescence in situ hybridization (FISH), and molecular analysis are useful in the diagnosis of sex chromosome aberrations. These methods were used in karyotype analysis of a 4-year-old girl with mild dysmorphism and growth retardation. Standard cytogenetic and FISH analysis was done on slides obtained from peripheral blood lymphocyte culture, and the molecular study was ...

background: in most mammals, sex is determined at the beginning of gestation by the constitution of the sex chromosomes, xy in males and xx in females. case: here we report an interesting case characterized by ambiguous genitalia and ovotestis in a newborn carrying an apparently female karyotype (46 xx). array comparative genomic hybridization (array-cgh) revealed an unbalanced rearrangement re...

second gamete. In each case, the broken end of the second chromosome 9 had no unsaturated end with which it could unite. As expected, this single broken end thereafter healed. Conclusions.-The experiments outlined allow some specific answers to be given to the questions presented in the first paragraph of this paper. Question (1) may be answered in the negative. Two chromosomes do not have to b...

The frequency of dicentric chromosomes in human peripheral blood lymphocytes at metaphase is considered as the "gold-standard" method for biological dosimetry and, presently, it is the most widely used for dose assessment. Yet, it needs lymphocyte stimulation and a 2-day culture, failing the requirement of rapid dose estimation, which is a high priority in radiation emergency medicine and triag...

Great articles often begin with an intriguing paradox, describe an elegant experimental approach, provide lasting and important data, and change the course of their discipline. Sturtevant and Beadle (1936) meets all of those criteria and stands as a paradigm for the genetic analysis of chromosome behavior in Drosophila. It began with two paradoxes, both ofwhichwere vexing but not obviously conn...