The Semipalatinsk nuclear test site area is considered to have been highly contaminated with radioactive fallout during 40 years of continuous nuclear testing. Individuals living near the nuclear test site are considered to have been exposed to both internal and external radiation. In order to assess the effects of prolonged radiation, a chromosome analysis was performed in lymphocytes from 123...

Background: Microdeletions of the long arm of the chromosome Y are the most common molecular genetic cause of severe infertility in men which affect three regions of AZFa, AZFb and AZFc (Azoospermia factor). These regions contain various genes involved in spermatogenesis. The effect of ethnicity on the patterns of Y chromosome microdeletions has not been extensively studied, particulary in Iran...

We designed a system to determine whether dicentric chromosomes in Drosophila melanogaster break at random or at preferred sites. Sister chromatid exchange in a Ring-X chromosome produced dicentric chromosomes with two bridging arms connecting segregating centromeres as cells divide. This double bridge can break in mitosis. A genetic screen recovered chromosomes that were linearized by breakage...

Ionizing radiation is the most powerful mutagen in environmental and working conditions. The result of genotoxic effect of radiation is the development of chromosome aberrations. The structural chromosome aberrations in peripheral blood lymphocytes are dicentric, ring, acentric fragment. The observation of chromosome aberration frequency in lymphocyte karyotype is the conclusive method to asses...

During the development of disomic additions of rye (Secale cereale L.) chromosomes to wheat (Triticum aestivum L.), two reverse tandem duplications on wheat chromosomes 3D and 4A were isolated. By virtue of their meiotic pairing, the reverse tandem duplications initiated the chromatid type of the breakage-fusion-bridge (BFB) cycle. This BFB cycle continued through pollen mitoses and in the earl...

The success of the Human Genome Project (HGP) has provided a blueprint for the approximately 20,000 gene-encoded proteins potentially active in all of the hundreds of cell types that make up the human body. Yet we still have limited knowledge about a majority of the gene-encoded proteins which are the “building blocks of life” and “cellular machinery”. It is estimated that for nearly half of th...

The telomeres of eukaryotes are stable open double-strand ends that coexist with nonhomologous end joining (NHEJ), the repair pathway that directly ligates DNA ends generated by double-strand breaks. Since a single end-joining event between 2 telomeres generates a circular chromosome or an unstable dicentric chromosome, NHEJ must be prevented from acting on telomeres. Multiple mechanisms mediat...

Secondary chromosome aberrations in de novo acute myeloid leukemia ( AML) are less specific and occur in addition to the primary chromosome abnormalities. Secondary chromosome aberration in acute nonlymphocytic leukemia has been recognized for many years as the most serious long-term complication of malignant disease. Our aim in this study was to focus on patients with AML associated with secon...

Most Robertsonian translocations are dicentric, suggesting that the location of chromosomal breaks leading to their formation occur in the acrocentric short arm. Previous cytogenetic and molecular cytogenetic studies have shown that few Robertsonian translocations retain ribosomal genes or beta-satellite DNA. Breakpoints in satellite III DNA, specifically between two chromosome 14-specific subf...

objective: microdeletions of the y chromosome long arm are the most common molecular genetic causes of severe infertility in men. they affect three regions including azoospermia factors (azfa, azfb and azfc), which contain various genes involved in spermatogenesis. the aim of the present study was to reveal the patterns of y chromosome microdeletions in iranian infertile men referred to royan i...