In the past few years much physical evidence has accumulated that the A-bomb survivors at Hiroshima were exposed to significant doses of neutrons, in contrast to the predictions of the current DS86 dosimetry. We discuss some biological measurements of exchange-type chromosomal aberrations in survivors at Hiroshima, which also strongly imply that the survivors received a significant neutron dose...

Annual fish which belong to the order Cyprinodontiformes constitute an excellent model for evolutionary studies. their short life cycle, distribution in ecologically dynamic environments, and low agility make them favorable for genetic analyses. The species Hypsolebias antenori (Rivulidae), encountered in seasonal pools located in the semiarid region of Northeastern Brazil, has been the object ...

The C-banding karyotype of the jerboas Allactaga tetradactyla, Jaculus jaculus jaculus, and Jaculus orientalis was described and interspecific relationships were discussed. Despite the conservation of a relatively small amount of C-heterochromatin located at the centromeric region of some chromosomes in all karyotypes, a striking loss of C-heterochromatin was clearly observed in J. orientalis. ...

During chromosome duplication, it is essential to replicate not only the DNA sequence, but also the complex nucleoprotein structures of chromatin. Pericentric heterochromatin is critical for silencing repetitive elements and plays an essential structural role during mitosis. However, relatively little is understood about its assembly and maintenance during replication. The Mi2/NuRD chromatin re...

A pericentric inversion in chromosome 1 of a severely oligospermic human male is reported. Pachytene analysis in microspread preparations shows an absence of full loop formation in the inversion bivalent and only the rare occurrence of a partial loop. The majority of cells exhibit extensive asynapsis across the inverted segment, or a normal looking synaptonemal complex indicative of heterologou...

The mitotic segregation apparatus composed of microtubules and chromatin functions to faithfully partition a duplicated genome into two daughter cells. Microtubules exert extensional pulling force on sister chromatids toward opposite poles, whereas pericentric chromatin resists with contractile springlike properties. Tension generated from these opposing forces silences the spindle checkpoint t...

Centromeres are more than just simple stretches of DNA that recruit the kineto-chore proteins required to bind spindle microtubules and segregate chromosomes during mitosis. In fact, the chromatin surrounding centromeres is organized into a spring-like structure that bridges the cen-tromeres of sister chromatids and resists the pull of spindle microtubules. The tension generated when sister kin...

With 82 species currently described, the genus <i>Leptodactylus</i> is most diverse and representative one in family Leptodactylidae. Concerning chromosomal organization, this represents an interesting underexplored group since data from molecular cytogenetics are incipient, little known about organization distribution of repetitive DNA elements karyotypes. In sense, study aimed at ...

MOTIVATION There have been several studies on the micro-inversions between human and chimpanzee, but there are large discrepancies among their results. Furthermore, all of them rely on alignment procedures or existing alignment results to identify inversions. However, the core alignment procedures do not take very small inversions into consideration. Therefore, their analyses cannot find invers...

Received 4 April 1972. * Cytogenetics Laboratory, Genetics Committee of the University of Iceland, Department of Pathology, Reykjavik, Iceland. t Paediatric Department, University Hospital Iceland; Home for the Mentally Retarded, K6pavogur; Paediatric Department, St Joseph's Hospital, Reykiavik, Iceland. t John F. Kennedy Instituttet, GI. Landevej 7-9, Copenhagen, Denmark. ** Faculty of Medicin...