Cytogenetic and Genome Research

Established in 2004, the Radiation and Nuclear Countermeasures Program (RNCP), within the National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH) has the central mission to advance medical countermeasure mitigators/therapeutics, and biomarkers and technologies to assess, triage, and inform medical management of patients experiencing acute radiation syndrome (ARS) and/or the delayed effects of acute radiation exposure (DEARE). The RNCP biodosimetry mission space encompasses: 1) basic research to elucidate novel approaches for rapid and accurate assessment of radiation exposure, 2) studies to support advanced development for U...

Constitutive heterochromatin, consisting of repetitive sequences, diverges very rapidly; therefore, its nucleotide sequences and chromosomal distributions are often largely different, even between closely related species. The chromosome C-banding patterns of two Gerbillinae species, Meriones unguiculatus and Gerbillus perpallidus, vary greatly, even though they belong to the same subfamily. To understand the evolution of C-positive heterochromatin in these species, we isolated highly repetitive sequences, determined their nucleotide sequences, and characterized them using chromosomal and filter hybridization...

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Radioiodine (131I) is widely used in the treatment of hyperthyroidism and as an effective ablative therapy for differentiated thyroid cancer (DTC). Radioiodine (131I) constitutes 90% of the currently used therapies in the field of nuclear medicine. Here, we report the cytogenetic findings of a long-term follow up study of 27 years on a male patient who received two rounds of radioiodine treatment within a span of 26 months between 1992 and 1994 for his papillary thyroid cancer. A comprehensive cytogenetic follow up study utilizing Cytokinesis Blocked Micronucleus (CBMN) assay, Dicentric Chromosome Assay (DCA), genome wide translocations and inversions was initiated on this patient since the first administration of radioiodine in 1992...

Following a mass-casualty nuclear/radiological event, there will be an important need for rapid and accurate estimation of absorbed dose for biological triage. The cytokinesis-block micronucleus (CBMN) assay is an established and validated cytogenetic biomarker used to assess DNA damage in irradiated peripheral blood lymphocytes. Here, we describe an intercomparison experiment between two biodosimetry laboratories, located at Columbia University (CU) and Health Canada (HC) that performed different variants of the human blood CBMN assay to reconstruct dose in human blood, with CU performing the assay on isolated lymphocytes and using semi-automated scoring whereas HC used the more conventional whole blood assay...

The Y chromosome is a haploid genome unique to males with no genes essential for life. It is easily transmitted to the next generation without being repaired by recombination, even if a major genomic structural alteration occurs. On the other hand, the Y chromosome genome is basically a genomic region transmitted only from father to son, reflecting a male-specific inheritance between generations. The Y chromosome exhibits genomic structural differences among different ethnic groups and individuals. The Y chromosome was previously thought to affect only male-specific phenotypes, but recent studies have revealed associations between the Y chromosomes and phenotypes common to both males and females, such as certain types of cancer and neuropsychiatric disorders...

Fluorescence live-cell microscopy is important in cell biology to perform artifact-free investigations. To analyze the dynamics of chromatin and centromeres at different stages of the cell cycle in nuclei and chromosomes we performed simultaneous EYFP-CENH3/H2B-DsRed and single H2B-YFP transformations in Arabidopsis wild-type and cohesin T-DNA mutants. All constructs were under the control of the strong CaMV 35S-promoter. While a strong silencing of fluorescence expression occurred differently in leaf and root tissues in the double transformants, nearly all single-transformed wild-type and most mutant cells showed H2B-YFP fluorescence...

The stingless bees Tetragonisca angustula and T. fiebrigi are widely distributed in Brazil, and both are commonly known as "jataí". Our goal was to investigate the possible origin of the B chromosomes in T. fiebrigi, a cytotaxonomic trait that differentiates T. fiebrigi from T. angustula. We analyzed diploid chromosome number, B chromosome incidence, patterns of constitutive heterochromatin, and in situ localization of different repetitive DNA probes in T. angustula and T. fiebrigi. Both species displayed 2n = 34, with similar karyotype structure...

Developmental and epileptic encephalopathy (DEE) refers to a group of severe epilepsy encephalopathy and development disorders, and its typical clinical features include seizures, drug resistance, and developmental delay or regression. To date, limited studies have reported DEEs driven by FGF13. Here, we reported a girl with DEE90 caused by variant of FGF13. Her electroencephalography (EEG) showed discontinuous hypsarrhythmia, and a heterozygous nonsynonymous variant in FGF13 [NM_004114.4: c.5C>G, p...

The cytokinesis-block micronucleus (CBMN) assay is a well-established method to assess radiation-induced genetic damage in human cells. This assay has been adapted to imaging flow cytometry (IFC), allowing automated analysis of many cells, and eliminating the need to create microscope slides. Furthermore, to improve the efficiency of assay performance, a small-volume method previously developed was employed. Irradiated human blood samples were cultured, stained, and analysed by IFC to produce images of the cells...

Chromosome 2p (chr2p) duplication, also known as trisomy 2p, is a rare chromosome abnormality associated with developmental delay, intellectual disability, behavioral problems, and distinctive facial features. Most of the reported cases involving trisomy 2p include additional copy number variants (CNVs) in other regions of the genome and are usually small in size. Little is known about the clinical outcomes of large duplications of chromosome 2p as the sole cytogenetic abnormality. In this study, 193 samples at the Greenwood Genetic Center (GGC) with CNVs involving chr2p were evaluated, out of which 86 had chromosome 2p duplications...

Intrachromosomal insertions are complex structural rearrangements that are challenging to interpret using classical cytogenetic methods. We report a male patient carrying a recombinant X chromosome derived from a maternally inherited intrachromosomal insertion. The patient exhibited developmental delay, intellectual disability, behavioral disorder, and dysmorphic facial features. To accurately identify the rearrangements in the abnormal X chromosome, additional cytogenetics studies were conducted, including fluorescence in situ hybridization (FISH), multicolor-banding FISH (mBAND) and array comparative genomic hybridization (aCGH)...

Ticks are haematophagous arthropods and obligate ectoparasites of humans and other animals. This study focused on the molecular discrimination of ticks in the tropical environment of Hainan according to multi-gene DNA barcode markers with the expectation of accurately distinguishing species. A total of 420 ticks, including 49 adult ticks, 203 nymphal ticks, and 168 larval ticks, were collected in the field, and the 49 adult ticks were identified as Rhipicephalus turanicus, Dermacentor marginatus, and Haemaphysalis longicornis...

Introduction Optical Genome Mapping (OGM) appears as a revolutionary tool consolidating analysis performed with standard cytogenetic methods (karyotype and array) into a single assay with performance that matches or exceeds that of these two methods combined. The chromosomal region 11p15.5 harbours two differentially methylated regions, the Imprinting Centre regions 1 and 2 (IC1, IC2). Disturbances of both regions alter human growth and are associated with two imprinting disorders, Beckwith-Wiedemann (BWS) and Silver Russell (SRS) syndromes...

In a nuclear or radiological incident, first responders must quickly and accurately measure radiation exposure among civilians, as medical countermeasures are radiation dose-dependent and time-sensitive. Although several approaches have been explored to measure absorbed radiation dose, there is an important need to develop point-of-care (POC) bioassay devices that can be used immediately to triage thousands of individuals potentially exposed to radiation.. Here we present a proof-of-concept study showing the use of a paper-based vertical flow immunoassay (VFI) to detect radiation dosimetry genes...

There is an increased threat of exposure to ionizing radiation, in the event of such exposure the availability of medical countermeasures will be vital to ensure the protection of the population. Effective countermeasures should be efficacious across a varied population and most importantly amongst both males and females. Radiation research must be conducted in animal models which act as a surrogate for the human response. Here we identify differences in survival in male and female C57BL/6 in both a total body irradiation (TBI) model using the Armed Forces Radiobiology Research Institute (AFRRI) 60Co source and a partial body irradiation (PBI) model using the AFRRI Linear Accelerator (LINAC) with 4MV photons and 2...

Radiation-related normal tissue injury sustained during cancer radiotherapy or in a radiological or mass casualty nuclear incident is a major health concern. Reducing the risk and mitigating consequences of radiation injury could have a broad impact on cancer patients and citizens. Efforts to discover biomarkers that can determine radiation dose, predict tissue damage, and aid medical triage are underway. Exposure to ionizing radiation causes changes in gene, protein and metabolite expression that needs to be understood to provide a holistic picture for treating acute and chronic radiation induced toxicities...

X chromosome inactivation (XCI) is an essential mechanism for gene dosage compensation between male and female cells in mammals. The Okinawa spiny rat (Tokudaia muenninki) is a native rodent in Japan with XX/XY sex chromosomes, like most mammals; however, the X chromosome has acquired a neo-X region (Xp) by fusion with an autosome. We previously reported that dosage compensation has not yet evolved in the neo-X region; however, X-inactive-specific transcript (Xist) RNA (long non-coding RNA required for the initiation of XCI) is partially localized in the region...

Quantification of gene expression signatures has been substantiated as a potential and rapid marker for radiation triage and biodosimetry during nuclear emergencies. Similar to the established biodosimetry assays, the gene expression assay has drawbacks such as being highly dynamic and transient, not specific to ionizing radiation, and also influenced by confounding factors such as gender, health status, lifestyle, and inflammation. In view of that, prior knowledge of baseline expression of certain candidate genes in a population could complement to discriminate the unexposed from exposed individuals without the need for individual pre-exposure controls...

We performed optical genome mapping (OGM), a newly developed cytogenetic technique, for a patient with a disorder of sex development (DSD) and a 46,XX,t(9;11)(p22;p13) karyotype. The results of OGM were validated using other methods. OGM detected a 9;11 reciprocal translocation and successfully mapped its breakpoints to small regions of 0.9-12.3 kb. OGM identified 46 additional small structural variants, only three of which were detected by array-based comparative genomic hybridization. OGM suggested the presence of complex rearrangements on chromosome 10; however, these variants appeared to be artifacts...