Earpits Syndrome in Children with Hearing Loss

Acta biologica Cracoviensia. Series botanica

The application of chromosome banding methods for plant karyosystematic studies is analyzed. The authors discuss ways of constructing C-band idiograms and interpretating the results of C-banding studies with respect to the polymorphism of heterochromatin and its histochemical differentiation. The role of quantitative changes of heterochromatin in evolution, its functional effect, and the division into dispensable and indispensable heterochromatin are presented. An overview of the recent literature on this subject is also given.

Reproductive Biology, 2019

Although the polymorphic heterochromatin regions of chromosomes (heteromorphisms) have been extensively studied for their phenotypic effects on humans, co-occurrences of chromosome 1, 9, 16 and Y heteromorphisms and of acrocentric variants have never been studied on humans with an objective scoring system. Here we compared the frequencies of individual heteromorphisms on a total of 602, 768 and 224 patients with the indications of infertility, recurrent miscarriage and in vitro fertilization (IVF) failure, respectively and on 272 controls. Then we examined whether there were significant co-occurrences between heteromorphisms within and between the groups. There were no statistically significant differences in the frequencies of heteromorphisms between the groups. Both statistically significant and non-significant correlations were observed within the non-acrocentric and certain acrocentric heteromorphisms in each group. When these co-occurrences were examined between the groups, a 2.2 fold increased risk of IVF failure in males in the presence of either chromosome 13 or chromosome 21 variants was observed (95 %CI:1.1-4.2). We conclude that the simultaneous manifestations of heteromorphisms have no effect on reproductive failure. There seems to be a correlation between the non-acrocentric heteromorphisms (1qh+, 9qh+, 16qh + and Yqh+/-), which might be the result of complex interactions of formation of these heterochromatin regions. The correlations observed between certain acrocentric chromosomes might be related to satellite association and nucleolus formation. The increased risk observed in males with IVF failure in the presence of either chromosome 13 or 21 variants should be interpreted cautiously due to the heterogeneity of the group.

Caryologia, 1998

Constitutive heterochromatin (HC = C-banding) distribution was studied in pig (Sus 5crofa) chromosomes from 20 animals belonging to Cinta Senese and Calabrese breeds raised in southern Italy. The use of CBG-banding, sequential GBG/CBA-banding and sequential GBG/ Ag-NOR/CBA-banding techniques allowed more detailed characterization of C-banding patterns in pig chromosomes (SSC). The following features were noticed: (a) all autosomes and the X-chromosome showed centromeric C-positive bands; (b) the entire q-arm and proximal part of the p-arm y chromosome were C-positive: (c) clear interstitial C-positive bands were noticed in SSC1q17, SSC3p14 and SSC16q21; (d) the nucleolus organizer (NO) chromosome 10 showed two distinct HCblocks very far apart in both arms with large, polymorphic (different size) NORs between the chromosome pair, while NO-chromosome 8 showed only one C-positive band (the smallest) in the qarms; (e) C-band polymorphism was observed between and within chromosome pairs also in related subjects (three generations were followed); (f) the C-banding patterns are inherited in Mendelian fashion; (g) the most common C-band polymorphic chromosomes pairs were SSC 1, 7, 9, 11, 12, 16, 17 and 18.

Molecular Cell, 2007

Chromosoma, 2001

The purpose of this investigation was twofold. The first objective was to demonstrate that, in most of ten mammalian species commonly used in biomedical research, not all constitutive heterochromatin (C-bands) represents telomeric DNA. For example, the C-bands in human chromosomes, the long arm of the X and the entire Y chromosome of Chinese hamster, and most of the short arms of Peromyscus and Syrian hamster chromosomes are not telomeric DNA. In addition to the usual terminal telomeric DNA in the chromosomes of these mammalian species, the pericentromeric regions of seven or eight Syrian hamster chromosomes and all Chinese hamster chromosomes except pair one have pericentromeric regions that hybridize with telomeric DNA, some in C-bands and some not. The second objective was to describe a simple fluorescence in situ hybridization (FISH) reverse-printing procedure to produce black-andwhite microphotographs of metaphase and interphase cells showing locations of telomeric DNA with no loss of resolution. Thus, at least three different types of heterochromatin (telomeric heterochromatin, nontelomeric heterochromatin and a combination of both) are present in these mammalian species, and this simple black-andwhite reverse printing of telomeric FISH preparations can depict them economically without sacrificing clarity.

Experimental Cell Research, 1971

The following features of the Indian muntjac (miniature Asian deer) make it ideal for cytogenetic studies: 1. A low chromosome number (female 6, male 7) with each chromosome individually identifiable: 2. Large chromosomes; 3. The nresence of a very long centromere region on a chromosome formed by fusion of the X-chromosome with an autosomal telocentric chromosome; 4. A nrominent secondary constriction on this autosomal telocentric chromosome. DNA replication studies demonstrate that the centromere regions and the Y chromosome undergo relatively intense replication during a short period occurring 5 to 7 h into the 8-h S period: Other portions of the chromosome complement continued replication after replication had ceased in these areas. These replicative characteristics indicated that all the centromere regions and the Y chromosome were heterochromatic. This was confirmed by staining for constitutive heterochromatin. The rest of the chromosomes showed a diffuse replication pattern during all periods of the S phase. It is suggested that any segmental labeling that may have been present was obscured by the high packing ratio of chromatin fibers into these large chromosomes. Measurements were made on the chromosomes with and without exposure to Colcemid. These indicated that the heterochromatic centromere region of the X-autosome chromosome remained long and narrow following Colcemid treatment while the non-heterochromatic regions became short and thick. These studies parallel the observations that following exposure to cold or Colcemid the heterochromatic areas in plant chromosomes tend to condense less than the euchromatic regions. These measurements also indicated that there was a gradient of chromosome contraction with the least contraction occurring in chromatin nearest the heterochromatin (or centromere) and the greatest contraction occurring in those segments furthest removed from the heterochromatin. Analytical ultracentrifugation of muntjac DNA showed a curve that was moderately nongaussian because of a heavy shoulder component constituting approx. 13 % of the total DNA. When the DNA was denatured, renatured for 5 h, and centrifuged a small satellite component constituting about 4 % of the total DNA became apparent. Similar studies of main band and heavy shoulder DNA isolated by preparative ultracentrifugation showed that the satellite was buried primarily within the main band DNA, indicating that its GC content was essentially the same as that of the main band. The heterochromatin staining reaction suggested that this rapidly renaturing DNA was probably localized to the centromeric heterochromatin. Centrifuaation after denaturation and martial renaturation indicated the heavy shoulder DNA did no> contain a disproportionate amount of rapidly renaturing DNA. After treatment with quinacrine mustard the fluorescent patterns showed a marked decrease in staining over the centromeric heterochromatin, in the region of the secondary constriction, and at numerous other bands in the chromosome arms. The fact that there was decreased staining in the centromeric heterochromatin, which was probably enriched in the rapidly renaturing fraction whose base composition was the same as that of the main band DNA, suggests that the base composition of DNA may play only a secondary or minor role in determining the fluorescent Exptl Cel l Res 67

Genetica, 1973

The distribution of heterochromatin in the chromosomes of the rat was determined by analysing two of its properties: late replication and differential stain with the DNA d-r method. The presence of late and non-late replicating c-heterochromatin in the genome of Rattus norvegicus indicates that this chromatin is an heterogeneous substance exhibiting different properties. Furthermore, the existence of heterochromatin formed by nonrepeated sequences or by sequences with a low degree of repetitiveness is suggested by the presence of late replicating areas which do not react with the DNA d-r method.

American Journal of Medical Genetics Part A, 2005

We applied comparative genomic hybridization (CGH) in six patients with de novo prenatal or postnatal extra marker chromosomes (MC). In four cases, MCs were mosaic and in one of them, the MC was detected in less than 50% of the cells. In three cases, CGH identified the origin of the extra MCs. In the other three, two prenatal cases and one child with an abnormal phenotype, CGH showed normal profiles. Among these cases, a normal profile and entirely C-band positive was identified suggesting that MC did not contain euchromatin. Genetic imbalances detected by CGH were as follow: a gain of 8p10-p12 in a boy with facial dysmorphism, hyperactivity and speech delay, a gain of 8q10-q12 in a healthy man with a history of spontaneous abortions, and a gain of 15q11-q13 in a girl with speech delay, and motor skill and object manipulation difficulties. Clinical data of these patients were compared with those reported in the literature. We conclude that CGH is a very useful and powerful tool for characterizing prenatal or postnatal MCs, even when the mosaicism is present and the MCs are present in less than 50% of the cells.

Human Genetics, 1987

The analysis of a sample of 100 isoacentric (IA) and isocentric (IC) chromosomes, which had originated from spontaneous or radiation-induced deletions in human lymphocytes, is reported. IC and also IA have a strong tendency to be formed after breakage in juxtacentromeric heterochromatin. When euchromatic regions are involved, the breaks are not distributed at random since they frequently occur at places where juxtacentromeric heterochromatin exists in other primate species. It is assumed that intercalary structures conserving some of the properties of heterochromatin exists in human chromosomes in intercalary positions.

Genome Biology, 2004

Assembly and characterization of heterochromatin and euchromatin on human artificial chromosomes <p>An assay of the formation of heterochromatin and euchromatin on de novo human artificial chromosomes containing alpha satellite DNA revealed that only a small amount of heterochromatin may be required for centromere function and that replication late in S phase is not a requirement for centromere function.</p> Abstract Background: Human centromere regions are characterized by the presence of alpha-satellite DNA, replication late in S phase and a heterochromatic appearance. Recent models propose that the centromere is organized into conserved chromatin domains in which chromatin containing CenH3 (centromere-specific H3 variant) at the functional centromere (kinetochore) forms within regions of heterochromatin. To address these models, we assayed formation of heterochromatin and euchromatin on de novo human artificial chromosomes containing alpha-satellite DNA. We also examined the relationship between chromatin composition and replication timing of artificial chromosomes.

Human Evolution, 1993

Image analysis can contribute to those fields of cytogenetics that are influenced most by subjectivity, especially evaluation of chromosome regions that are histochemically polymorphic. C-banding of human or primate chromosomes may be used as a typical example of this concept. In addition, using it quantitatively it is useful in studies of population cytogenetics of man and Primates. Therefore, the aim of this study was to determine the best conditions for measurement by image analysis of C-positive regions in a sample of 29 normal subjects. We looked for relationships of chromosomal C-positive areas with the dimensions of the corresponding metaphases. Finally, we suggest some criteria for potential use of C-banding in population and comparative studies.

Chromosoma, 1990

Heterochromatin (May 9-t3, 1990) brought some 70 geneticists, cytologists and molecular biologist to the lovely village of Alberobello in the Italian countryside near Bart. The meeting, organized by S. Pimpinelli and S. Gatti, was a lively one; considerable progress is being made in sorting out the differences and the similarities in the multiple elements that are too often lumped under the single heading of heterochromatin. Although the work presented was limited to studies of Drosophila, the findings should apply to heterochromatin in all organisms. The varieties of questions considered can be illustrated by the session topics, which we will use as' a framework for our thoughts on the discussions. This commentary reflects our personal views and is not an attempt to give a balanced review of the subject. Where specific presentations at the Workshop are mentioned, the name and institution of the speaker are given. Where possible, we have cited a recent relevant reference as an entry to the literature for the interested reader.

Cytogenetic and Genome Research

Trends in Plant Science, 2004

Cell identity is determined by the nuclear program and established by a complex molecular interplay between DNA sequence and proteins. The past few years have witnessed major breakthroughs in the elucidation of this intricate mechanism of epigenetic gene regulation. Covalent modifications in cytosine residues of DNA and in histone tails are revealed as hallmarks that establish the functional status of chromatin domains. In particular, our knowledge of the functional implication of histone tail modifications, known as the histone code, has rapidly increased. Cytogenetics has taken a prominent share in this expanding research field by linking nuclear structures with biochemical features such as gene activity, DNA replication, histone modification and DNA methylation. This review summarizes the role of cytogenetics in exploring the mechanism underlying higher order gene regulation.

Experimental Cell Research, 1990