Zeitschriftenartikel: „Heterochromatin polymorphism“

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Hatsumi, Machiko. „Karyotype polymorphism in Drosophila albomicans“. Genome 29, Nr. 3 (01.06.1987): 395–400. http://dx.doi.org/10.1139/g87-069.

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Supernumerary (B) chromosomes are present in Thai, Malay, and Burmese populations of Drosophila albomicans (2n = 6) in a polymorphic state. Although usually stable at mitosis, their numbers differed between individuals and their frequency was also different between isofemale lines and between populations. Arm 3 of the X3 chromosome was polymorphic for the presence and the size of a procentric heterochromatic segment. Chromosome 4 is polytypic for variation in length governed by differences in the amount of heterochromatin and the long variant is polymorphic for the location of its secondary constriction. Key words: Drosophila albomicans, karyotype polymorphism, B chromosome.

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Taran Kyzy, Jafar Aliyev. „Value heterochromatin and polymorphic varian gene folat cycle in women with miscarried and losses of pregnancy“. HEALTH OF WOMAN, Nr. 9(115) (30.11.2016): 148–51. http://dx.doi.org/10.15574/hw.2016.115.148.

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The article presents data from surveys of women of losses of pregnancy (LP) in history, conducted within the medical genetic counseling, given the urgency of specifying genetic factors that actually are in causal connection with the LP specification clinical effects of epigenetic variability. The objective: to clarify the meaning of the changes in women heterochromatin (chromosomal polymorphism) and polymorphic variants of genes folat cycle enzymes as potential risk factors and pathogenic primordial LP. Patients and methods. The study involved two groups of women: I - 154 observations with complicated obstetric history in LP and II - 32 healthy women with uncomplicated reproductive history, held preconception planning to prevent pregnancy. Studied genealogical history, especially of internal organs, genitalia. Special studies included cytogenetic analysis, identification of gene polymorphisms system folat cycle methylentetrahydrofolate reductase [MTHFR] (C677T, A1298C, G1793A); methionine synthase reductase [MTRR] (A66G). Results. Women with a history of LP in 36.4% identified chromosome polymorphisms (SNPs extreme variants of chromosome polymorphism) on the background of various risk alleles of polymorphic variants of genes folat cycle; 7.1% of them is a polymorphism of the 21st chromosome. These genetic features are interpreted as a significant risk factor for LP as grounds for targeted in-depth medical and genetic examination. Prevalence among women with a history of PL undifferentiated forms cjnnective tissue and mesoderm dysplasia, benign tumors and «precancerous» states, as well as the prevalence of cardiovascular and psycho-neurological disease in pedigree suggests pathogenetic link these phenomena, the role of chromosomal polymorphism and polymorphic variants of genes of pathogenic folat cycle as primordial. Conclusion. The data on the place and role of heterochromatin and gene polymorphisms folat cycle in the origin LP should be mandatory option when examining women within the medical genetic counseling. Key words: pregnancy, reproductive losses, chromosomal instability, folat cycle genes, ancestry.

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Sharma, Atashi, Nicholas A. Kinney, Vladimir A. Timoshevskiy, Maria V. Sharakhova und Igor V. Sharakhov. „Structural Variation of the X Chromosome Heterochromatin in the Anopheles gambiae Complex“. Genes 11, Nr. 3 (19.03.2020): 327. http://dx.doi.org/10.3390/genes11030327.

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Heterochromatin is identified as a potential factor driving diversification of species. To understand the magnitude of heterochromatin variation within the Anopheles gambiae complex of malaria mosquitoes, we analyzed metaphase chromosomes in An. arabiensis, An. coluzzii, An. gambiae, An. merus, and An. quadriannulatus. Using fluorescence in situ hybridization (FISH) with ribosomal DNA (rDNA), a highly repetitive fraction of DNA, and heterochromatic Bacterial Artificial Chromosome (BAC) clones, we established the correspondence of pericentric heterochromatin between the metaphase and polytene X chromosomes of An. gambiae. We then developed chromosome idiograms and demonstrated that the X chromosomes exhibit qualitative differences in their pattern of heterochromatic bands and position of satellite DNA (satDNA) repeats among the sibling species with postzygotic isolation, An. arabiensis, An. merus, An. quadriannulatus, and An. coluzzii or An. gambiae. The identified differences in the size and structure of the X chromosome heterochromatin point to a possible role of repetitive DNA in speciation of mosquitoes. We found that An. coluzzii and An. gambiae, incipient species with prezygotic isolation, share variations in the relative positions of the satDNA repeats and the proximal heterochromatin band on the X chromosomes. This previously unknown genetic polymorphism in malaria mosquitoes may be caused by a differential amplification of DNA repeats or an inversion in the sex chromosome heterochromatin.

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Amores, A., G. Martinez, J. Reina und M. C. Alvarez. „Karyotype, C-banding, and Ag-NOR analysis in Diplodus bellottii (Sparidae, Perciforms). Intra-individual polymorphism involving heterochromatic regions“. Genome 36, Nr. 4 (01.08.1993): 672–75. http://dx.doi.org/10.1139/g93-090.

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A karyotype analysis was carried out in nine specimens of the Sparid species Diplodus bellottii using conventional staining, as well as C-banding and Ag-NOR banding techniques, showing, respectively, 2n = 46 and fundamental number (FN) = 54, and scarce heterochromatic areas irregularly distributed and up to four NOR active regions that were C positive. When compared with the karyotypes of other related species, one centric fusion giving rise to a large metacentric pair and several pericentric inversions seem to have been involved in the karyotype evolution. An intra-individual polymorphism was detected in one specimen, resulting in two karyotypic forms in roughly identical proportion, owing to a larger C-band by the NOR regions, appearing either in a terminal position of the short arms of pair 2 or in telomeric position of pair 3. These findings suggest that the extra heterochromatic segment responsible for the heteromorphism apparently only involves associated heterochromatin and not the NORs themselves. This C-positive block seems to have eventually been transferred between heterologous NOR chromosomes by a somatic event, facilitated by the physical proximity of NOR pairs in the nucleolus.Key words: Sparidae, karyotype, heterochromatin, nucleolus organizers, chromosome polymorphism.

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Asamizu, Erika, Kenta Shirasawa, Hideki Hirakawa, Shusei Sato, Satoshi Tabata, Kentaro Yano, Tohru Ariizumi, Daisuke Shibata und Hiroshi Ezura. „Mapping of Micro-Tom BAC-End Sequences to the Reference Tomato Genome Reveals Possible Genome Rearrangements and Polymorphisms“. International Journal of Plant Genomics 2012 (27.11.2012): 1–8. http://dx.doi.org/10.1155/2012/437026.

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A total of 93,682 BAC-end sequences (BESs) were generated from a dwarf model tomato, cv. Micro-Tom. After removing repetitive sequences, the BESs were similarity searched against the reference tomato genome of a standard cultivar, “Heinz 1706.” By referring to the “Heinz 1706” physical map and by eliminating redundant or nonsignificant hits, 28,804 “unique pair ends” and 8,263 “unique ends” were selected to construct hypothetical BAC contigs. The total physical length of the BAC contigs was 495, 833, 423 bp, covering 65.3% of the entire genome. The average coverage of euchromatin and heterochromatin was 58.9% and 67.3%, respectively. From this analysis, two possible genome rearrangements were identified: one in chromosome 2 (inversion) and the other in chromosome 3 (inversion and translocation). Polymorphisms (SNPs and Indels) between the two cultivars were identified from the BLAST alignments. As a result, 171,792 polymorphisms were mapped on 12 chromosomes. Among these, 30,930 polymorphisms were found in euchromatin (1 per 3,565 bp) and 140,862 were found in heterochromatin (1 per 2,737 bp). The average polymorphism density in the genome was 1 polymorphism per 2,886 bp. To facilitate the use of these data in Micro-Tom research, the BAC contig and polymorphism information are available in the TOMATOMICS database.

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Jouve, Nicolas, Carmen Galindo, Montserrat Mesta, Fernando Diaz, Beatriz Albella, Pilar Garcia und Consuelo Soler. „Changes in triticale chromosome heterochromatin visualized by C-banding“. Genome 32, Nr. 5 (01.10.1989): 735–42. http://dx.doi.org/10.1139/g89-506.

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The distribution and characterization of heterochromatin in a series of cultivars, parents, new amphiploids and progeny of hexaploid triticale were comparatively studied using C-banding and morphometric analysis. A high level of intervarietal polymorphism was detected for the banding pattern. The chromosome pairs 4A and 1R presented the most constant pattern of heterochromatin distribution among 31 triticale lines studied. A total of 126 bands have been catalogued, from which 28, 59, and 39 belong, respectively, to the A, B and R genomes. The ratio of polymorphic bands per genome was 23/28, 36/59, and 30/39. The chromosomes displayed heterochromatin modifications consistent in both presence–absence and relative length of their content per genome, when passed from the parents to the amphiploids. Variations in the heterochromatin were also observed among sister plants coming from crosses between wheat and triticale. The heterochromatin content showed gradual tendencies either to increase or decrease in each genome during successive self-cross generations after that cross. The existence of a systematic process of variation of heterochromatin content in triticale is assumed, and the nature of this phenomenon is discussed.Key words: triticale, tetraploid wheat, rye, C-banding, heterochromatin.

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Mayr, B., G. Geber, H. Auer, M. Kalat und W. Schleger. „Heterochromatin composition and nucleolus organizer activity in four canid species“. Canadian Journal of Genetics and Cytology 28, Nr. 5 (01.10.1986): 744–53. http://dx.doi.org/10.1139/g86-105.

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Sequential staining with a counterstain-contrasted fluorescent banding technique (chromomycin A3 – distamycin A – DAPI) revealed the occurrence of distamycin A – 4,6-diamidino-2-phenylindole (DA–DAPI) staining heterochromatin in the centromeric regions of chromosomes 33, 36, 37, and 38 in the wolf (Canis lupus pallipes) and of chromosomes 13, 16, and 23 in the blue fox (Alopex lagopus). The red fox (Vulpes vulpes) lacked such regions. Staining with DAPI – actinomycin D produced a QFH-type banding pattern with clearcut differences in the staining behaviour of DA–DAPI positive regions between these three canid species. Staining with the fluorochrome D 287/170 did not preferentially highlight any of the DA–DAPI positive regions in any of them. Counterstain-enhanced chromomycin A3 R-banding and studies of nucleolus organizer region location and activity confirmed a close relationship between the karyotype of the wolf and the domestic dog. Few heterochromatic marker bands were encountered in these two species, but heterochromatin polymorphism was evident in the blue fox.Key words: Canidae, heterochromatin, nucleolus organizers.

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Cabrero, Josefa, und Juan Pedro M. Camacho. „Population cytogenetics of Chorthippus vagans. I. Polymorphisms for pericentric inversion and for heterochromatin deletion“. Genome 29, Nr. 2 (01.04.1987): 280–84. http://dx.doi.org/10.1139/g87-048.

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Two different polymorphisms have been identified in natural populations of the grasshopper Chorthippus vagans. One of these involved an inversion polymorphism in the M7 chromosome and was present in two populations from Granada. In one of these, from Prados del Pinar, the frequency of this polymorphism was constant over three consecutive generations, and meiotic studies of heterozygous individuals indicated that this inversion had not effect on male fertility. The second polymorphism involved a deletion of the distal C-band of the short arm of the M4 chromosome, which was observed in three different populations. From the observed difference between its frequency in adults and embryos in one of these populations, that of Prados del Pinar, it would appear that this deletion is strongly selected against. Despite this, its frequency was maintained in adult individuals of this population over 2 consecutive years. Complete meiotic drive in favour of the M4–d chromosomes in heterozygous females would explain the maintenance of its frequency despite the fact that it is counterselected. Key words: Chorthippus, inversion, heterochromatin, polymorphism (chromosome), meiotic drive.

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Di Meo, G. P., A. Perucatti, L. Iannuzzi, M. T. Rangel-Figueiredo und L. Ferrara. „Constitutive heterochromatin polymorphism in river buffalo chromosomes“. Caryologia 48, Nr. 2 (Januar 1995): 137–46. http://dx.doi.org/10.1080/00087114.1995.10797323.

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Ahearn, Jayne N., und Visut Baimai. „Cytogenetic study of three closely related species of Hawaiian Drosophila“. Genome 29, Nr. 1 (01.02.1987): 47–57. http://dx.doi.org/10.1139/g87-008.

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Three allopatric species from the Hawaiian islands, Drosophila bostrycha (Molokai), D. affinidisjuncta (West Maui), and D. disjuncta (East Maui), are extremely similar in morphology but differ in metaphase chromosomes by the amount and distribution of heterochromatin. Their polytene chromosomes are virtually homosequential with only slight differences at the tip of the microchromosome. Each is polymorphic for one or more inversions, especially in chromsome 4. Salivary gland chromosomes of F1 larvae reared either from wild-caught females or wild-caught males mated to standard laboratory stocks were examined for gene arrangements. Drosophila bostrycha and D. affinidisjuncta share a polymorphism for inversion 4v, which is much more frequent in the latter than in the former. In D. disjuncta 4v has been found only joined in a haplotype with three other inversions (g2 h2 i2) at a low frequency at Kipahulu Valley. Drosophila disjuncta is unique in having another fourth chromosome inversion, 4k, which is highest in frequency at Waikamoi. A new inversion, 2s, was discovered at Uluini Stream. Interspecific hybridizations were carried out in small mass matings. Backcrosses and dissections demonstrated that all F1 females were fertile. All F1 males were sterile in either of two categories with reciprocal hybrids uniformly manifesting one or the other type. Attempts to model the sterility mechanism suggest that more than chromosomal sterility is involved. Our results are discussed in relation to other closely related clusters of species having heterochromatin-based karyotype variations. Key words: heterochromatin, hybrid sterility, inversion, polymorphism, species divergence.

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Buño, I., J. L. Fernández, C. López-Fernández, J. L. Díez-Martín und J. Gosálvez. „Sau3A in situ digestion of human chromosome 3 pericentromeric heterochromatin. I. Differential digestion of α-satellite and satellite 1 DNA sequences“. Genome 44, Nr. 1 (01.02.2001): 120–27. http://dx.doi.org/10.1139/g00-088.

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In situ digestion with the restriction endonuclease (RE) Sau3A (Sau3A REISD) uncovers a polymorphism for the pericentromeric heterochromatin of human chromosome 3, which can be positively stained (3+) or not (3), and has proven useful to differentiate donor and recipient cells after sex-matched bone marrow transplantation and to analyze the so-called hemopoietic chimerism. The aim of the present investigation was to obtain insight into the molecular basis of such polymorphism to optimize its use for chimerism quantification using methodological approaches other than REISD. To this end, fluorescence in situ hybridization (FISH) assays using probes for the satellite DNA sequences that mainly constitute chromosome 3 pericentromeric heterochromatin (α-satellite and satellite 1 DNA) were performed on control and Sau3A-digested chromosomes. The results obtained suggest that chromosome 3 α-satellite DNA is digested in all individuals studied, irrespective of the karyotype obtained by Sau3A REISD (3++, 3+, 3--), and thus it does not seem to be involved in the polymorphism uncovered by Sau3A on this chromosome. Satellite 1 DNA is not digested in any case, and shows a polymorphism for its domain size, which correlates with the polymorphism uncovered by Sau3A in such a way that 3+ chromosomes show a large domain (3L) and 3 chromosomes show a small domain (3S). It seems, therefore, that the cause of the polymorphism uncovered by Sau3A on the pericentromeric region of chromosome 3 is a difference in the size of the satellite 1 DNA domain. Small satellite 1 DNA domains fall under the resolution level of REISD technique and are identified as 3.Key words: heterochromatin, α-satellite DNA, classical satellite DNA, satellite 1 DNA, restriction endonucleases, FISH.

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Hale, David W., und Ira F. Greenbaum. „Chromosomal pairing in deer mice heterozygous for the presence of heterochromatic short arms“. Genome 30, Nr. 1 (01.02.1988): 44–47. http://dx.doi.org/10.1139/g88-008.

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The pattern of chromosomal pairing was analyzed in male deer mice (Peromyscus maniculatus and Peromyscus sitkensis) heterozygous for the presence of heterochromatic short arms. G- and C-banding of somatic metaphases indicated that the presence of heterochromatic short arms increased the length of chromosome 4 by 15% in P. sitkensis and that of chromosome 8 by 9% in P. maniculatus. Analysis of silver-stained late zygotene and early pachytene nuclei revealed a low frequency of unequal axial lengths in the synaptonemal complexes corresponding to the heteromorphic bivalents. All mid- and late pachytene nuclei, however, exhibited fully paired synaptonemal complexes with equalized axial lengths. These observations suggest the existence of an adjustment mechanism which functions to equalize the lengths of the two axes of the heteromorphic synaptonemal complex.Key words: synaptonemal complex, Peromyscus, heterochromatin, chromosomal polymorphism, synaptic adjustment.

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Lundgren, Rolf, Roland Berger und Ulf Kristoffersson. „Constitutive heterochromatin C-band polymorphism in prostatic cancer“. Cancer Genetics and Cytogenetics 51, Nr. 1 (Januar 1991): 57–62. http://dx.doi.org/10.1016/0165-4608(91)90008-i.

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Bardhan, Amit, und T. Sharma. „Sequential meiotic prophase development in the pubertal Indian pygmy field mouse: Synaptic progression of the XY chromosomes, autosomal heterochromatin, and pericentric inversions“. Genome 43, Nr. 1 (01.02.2000): 172–80. http://dx.doi.org/10.1139/g99-080.

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Sequential meiotic prophase development has been followed in the pubertal male pygmy mouse Mus terricolor, with the objective to identify early meiotic prophase stages. The pygmy mouse differs from the common mouse by having large heterochromatic blocks in the X and Y chromosomes. These mice also show various chromosomal mutations; for example, fixed variations of autosomal short arms heterochromatin among different chromosomal species and pericentric inversion polymorphism. Identification of prophase stages was crucial to analyzing effects of heterozygosity for these chromosomal changes on the process of homologous synapsis. Here we describe identification of the prophase stages in M. terricolor, especially the pachytene substages, on the basis of morphology of the XY bivalent. Based on this substaging, we show delayed pairing of the heterochromatic short arms, which may be the reason for their lack of chiasmata. The identification of precise pachytene substages also reveals an early occurrence of "synaptic adjustment" in the pericentric inversion heterobivalents, a mechanism that would prevent chiasma formation in the inverted segment and thereby would abate adverse effects of such heterozygosity. The identification of pachytene substages would serve as the basis to analyze the nature of synaptic anomalies met in M. terricolor hybrids (which will be the basis of a subsequent paper). Key words: Mus terricolor, meiotic synapsis, sex chromosomes, pericentric inversion, heterochromatin.

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Mukhopadhyay, Saswati, Sujoy Dasgupta, Kushagradhi Ghosh und Tania Mukherjee. „Investigating the relation between chromosomal polymorphism and recurrent pregnancy loss: A cohort study“. Indian Journal of Obstetrics and Gynecology Research 9, Nr. 3 (15.08.2022): 391–96. http://dx.doi.org/10.18231/j.ijogr.2022.074.

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Chromosomal polymorphisms (CPM) are minor variation of karyotype, found in >1% of the general population. Heterochromatin, the inactive part of the chromosome, shows frequent polymorphism - increase/decrease in length. Recently, studies show that heterochromatin is not inert, but contains genes essential for spindle attachment, chromosome movement, meiotic pairing, and sister chromatid cohesion. Balanced translocation in parents, reciprocal and robertsonian, can disrupt important genes, and produce gametes with unbalanced gene dosage, causing spontaneous miscarriage. To correlate between chromosomal polymorphisms/ structural alterations and first trimester Recurrent Pregnancy Loss (RPL) primary infertility. : 100 couples with primary infertility or RPLs, were karyotyped by 72-h whole blood culture. Giemsa banding (GTG) was done in all cases. 20 metaphases were analysed according to the ISCN criteria. The total no. of RPLs was noted for each couple with abnormal karyotype. Of the 44 couples with abnormal karyotype, 36 (82%) had chromosomal polymorphism, 7 (16%) showed structural abnormality and 1 (2%) had numerical abnormality. Chromosome 9qh+ was present in the majority (33.33%). Among the D, G chromosomes, chromosome 15ps+/pstk+ were found in 22.22% but average no. of RPL was 2.15, whereas average RPL in Chr.22ps+ (incidence 5.55%.) was 3 (highest). Among male partners, Chr.Yqh+/Yqh- were found in 12 (33.33%) couples. Among the structural abnormalities (16%), balanced translocation accounted for 11.36%, maximum of which were Reciprocal translocations. The frequency of chromosomal abnormalities is higher among couples with RPLs and infertility, compared to the general population. Karyotyping gives important genetic information, thus acting as a good diagnostic tool, and helps to plan ART or perform prenatal testing.

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Chatterjee, Basanti, und P. K. Ghosh. „Constrcutive heterochromatin polymorphism and chromosome damage in viral hepatitis“. Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 210, Nr. 1 (Januar 1989): 49–57. http://dx.doi.org/10.1016/0027-5107(89)90043-2.

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Panzera, Fco, F. Alvarez, J. Sanchez-Rufas, R. Pérez, J. A. Suja, E. Scvortzoff, J. P. Dujardin, E. Estramil und R. Salvatella. „C-heterochromatin polymorphism in holocentric chromosomes of Triatoma infestans (Hemiptera: Reduviidae)“. Genome 35, Nr. 6 (01.12.1992): 1068–74. http://dx.doi.org/10.1139/g92-164.

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This is the first report of intraspecific variation of C-bands in Heteroptera, described in natural populations of Triatoma infestans (Hemiptera: Reduviidae), the main vector of Chagas disease in Uruguay. Marked variation in number, position, and size of C-heterochromatic bands was found in the three large autosomal pairs. A geographical pattern of this chromosomal polymorphism was observed. Evolutionary importance and epidemiological relevance are discussed.Key words: Triatoma infestans, cytogenetics, C-band polymorphism, holocentric chromosomes, Chagas disease.

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López-León, M. D., A. Martín-Alganza, M. C. Pardo, J. Cabrero und J. P. M. Camacho. „Temporal frequency stability and absence of effects on mating behaviour for an autosomal supernumerary segment in two natural populations of the grasshopper Eyprepocnemis plorans“. Genome 38, Nr. 2 (01.04.1995): 320–24. http://dx.doi.org/10.1139/g95-040.

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Interannual evolution of a polymorphism for a supernumerary segment in the smallest autosome of the grasshopper Eyprepocnemis plorans has been analysed in two natural populations. The polymorphism seemed to be stable in both populations, despite its undertransmission through heterozygous females carrying B chromosomes. Analyses of the effects of the extra segment on mating behaviour failed to show differential mating success in any sex or consistent effects on mating pattern. These results are discussed in relation to the maintenance of this polymorphism in natural populations.Key words: supernumerary segments, heterochromatin, repetitive DNA.

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Raskina, Olga, Alexander Belyayev und Eviatar Nevo. „Repetitive DNAs of wild emmer wheat (Triticum dicoccoides) and their relation to S-genome species: molecular cytogenetic analysis“. Genome 45, Nr. 2 (01.04.2002): 391–401. http://dx.doi.org/10.1139/g01-142.

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We have analyzed the chromosomal GISH molecular banding patterns of three populations of the wild allopolyploid wheat Triticum dicoccoides in an attempt to unravel the evolutionary relationships between highly repetitive DNA fractions of T. dicoccoides and proposed diploid progenitors of the B genome. Aegilops speltoides showed almost complete affinity of its repetitive DNA to C-heterochromatin of T. dicoccoides, whereas other S-genome species demonstrated relatedness only to distal heterochromatin. This substantiates the priority of Ae. speltoides as the most similar to the wheat B-genome donor in comparison with other Sitopsis species. Using molecular banding technique with DNA of different Aegilops species as a probe permits tracing of the origin of each heterochromatin cluster. Molecular banding analysis reveals polymorphism between three wild emmer wheat populations. Comparison of molecular banding patterns with chromosomal distribution of the Ty1-copia retrotransposons, which constitute a large share of T. dicoccoides genome, makes it possible to propose that the activity of transposable elements may lie in the background of observed intraspecific polymorphism.Key words: Aegilops, evolution, heterochromatin, Ty1-copia retrotransposons, Triticum.

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González, Graciela Esther, und Lidia Poggio. „Intragenomic Conflict between Knob Heterochromatin and B Chromosomes Is the Key to Understand Genome Size Variation along Altitudinal Clines in Maize“. Plants 10, Nr. 9 (08.09.2021): 1859. http://dx.doi.org/10.3390/plants10091859.

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In maize, we studied the causes of genome size variation and their correlates with cultivation altitude that suggests the existence of adaptive clines. To discuss the biological role of the genome size variation, we focused on Bolivian maize landraces growing along a broad altitudinal range. These were analyzed together with previously studied populations from altitudinal clines of Northwestern Argentina (NWA). Bolivian populations exhibited numerical polymorphism for B chromosomes (Bs) (from 1 to 5), with frequencies varying from 16.6 to 81.8 and being positively correlated with cultivation altitude. The 2C values of individuals 0B (A-DNA) ranged between 4.73 and 7.71 pg, with 58.33% of variation. The heterochromatic knobs, detected by DAPI staining, were more numerous and larger in individuals 0B than in those with higher doses of Bs. Bolivian and NWA landraces exhibited the same pattern of A-DNA downsizing and fewer and smaller knobs with increasing cultivation altitude, suggesting a mechanistic link among heterochromatin, genome size and phenology. The negative association between the two types of supernumerary DNA (knob heterochromatin and Bs), mainly responsible for the genome size variation, may be considered as an example of intragenomic conflict. It could be postulated that the optimal nucleotype is the result of such conflict, where genome adjustment may lead to an appropriate length of the vegetative cycle for maize landraces growing across altitudinal clines.

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Hashimoto, Diogo Teruo, und Fábio Porto-Foresti. „Chromosome polymorphism of heterochromatin and nucleolar regions in two populations of the fish Astyanax bockmanni (Teleostei: Characiformes)“. Neotropical Ichthyology 8, Nr. 4 (2010): 861–66. http://dx.doi.org/10.1590/s1679-62252010000400016.

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Karyotype and other chromosomal markers as revealed by C-banding and silver (Ag) impregnation in two Astyanax bockmanni populations (Barra Seca Stream and Campo Novo River) were examined. The diploid chromosome number 2n = 50 and nearly identical karyotypes were documented. C-banding revealed heterochromatic blocks on the terminal regions of some chromosomes, with high frequencies of polymorphisms. The Ag-impregnation showed that the nucleolus organizer regions (NORs) varied in number, location and organization. Astyanax bockmanni revealed chromosome characteristics similar those of the species complex "A. scabripinnis". Mechanisms that may be responsible for the high degree of polymorphism are discussed.

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Harshini, Vemula, P. Kumarasamy und S. M. K. Karthickeyan. „A rare chromosomal polymorphism in a Kangayam bull (Bos indicus) of south India“. Comparative Cytogenetics 15, Nr. 4 (15.12.2021): 459–65. http://dx.doi.org/10.3897/compcytogen.v15.i4.71295.

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A chromosomal polymorphism was detected on karyological screening of Kangayam breeding sires prior to subjecting them for frozen semen collection. One bull possessed the chromosomal complement 2n = 60, consisting of 58 acrocentric autosomes, one large sub-metacentric X-chromosome, and one small acrocentric Y-chromosome with a small visible p-arm, which was further confirmed using CBG- and GTG-banding. This polymorphism was attributed to a heterochromatin variation of the acrocentric Y-chromosome routine in the Bos indicus Linnaeus, 1758 cattle.

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Belyayev, Alexander, Elyzabeth Punina und Valery Grif. „Intrapopulation and individual polymorphism of heterochromatin segments inTrillium camschatcenseKer.-Gawl.“ Caryologia 48, Nr. 2 (Januar 1995): 157–64. http://dx.doi.org/10.1080/00087114.1995.10797325.

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Maffei, Eliane M. D., M. A. Marin-Morales, P. M. Ruas, C. F. Ruas und N. I. Matzenbacher. „Chromosomal polymorphism in 12 populations of Mikania micrantha (Compositae)“. Genetics and Molecular Biology 22, Nr. 3 (September 1999): 433–44. http://dx.doi.org/10.1590/s1415-47571999000300025.

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Mikania micrantha is a climbing perennial weed of the family Asteraceae, with a vast distribution from South America to south of the United States. This species is widely distributed throughout Brazil, where it shows little morphological variation. Mitotic chromosomes of 12 populations of M. micrantha derived from several Brazilian sites were studied using Feulgen staining and C-banding. The populations included eight diploid (2n = 36 and 42) and four tetraploid (2n = 72) cytotypes. Chromosome numbers of 2n = 36 and 2n = 42 are reported for the first time for M. micrantha. These populations had a secondary constriction in the middle of the larger arm of chromosome pair 1, following the same pattern described for all Mikania species analyzed so far. Numerical and structural variation of the chromosomes was quite common among the karyotypes and nearly all cytotypes differed from each other in some aspect. Most of the chromosomal differentiation may be attributed to inversions and addition or deletion of DNA fragments. C-banding, applied to three of the 12 populations, also revealed polymorphism in the distribution of heterochromatin. Additionally, one to 14 supernumerary or B-chromosomes were observed. The Bs were detected in six of the 12 populations and varied in size, number, and structure among karyotypes and also among cells of the same root meristem. The B chromosomes were also heterochromatic, showing a C-banding pattern similar to the A chromosomes, and suggesting that they may be derived from the chromosomes of the A complement.

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Sangines, N., und M. Aguilera. „Chromosome polymorphism in Holochilus venezuelae (Rodentia: Cricetidae): C- and G-bands“. Genome 34, Nr. 1 (01.02.1991): 13–18. http://dx.doi.org/10.1139/g91-003.

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Karyological analysis of C- and G-banding patterns of 44 specimens of Holochilus venezuelae revealed six distinct karyomorphs, which were designated as follows: I (2n = 44; fundamental number (FN) = 56); II (2n = 45; FN = 58); IV (2n = 43; FN = 56);V(2n = 44; FN = 58); IV-a(2n = 42; FN = 56); and V-a (2n = 44; FN = 58). This chromosomal polymorphism is interpreted as the result of (i) one or two Robertsonian changes of the centric-fusion type, originating from one member of chromosome pair 10 and one of pair 11 (in karyotypes IV and V) and two metacentric chromosomes from pairs 10 and 11 (in karyotype IV-a); (ii) one pericentric inversion (in karyotype V-a) forming one submetacentric chromosome from the metacentric fusion product described above; and (iii) the presence of B chromosomes, which are almost completely heterochromatic and do not pair with any member of group A. The pattern of C-banding reveals that the first five pairs of metacentric chromosomes contain very little centromeric heterochromatin, while pair 6 and the fusion chromosomes (10/11 F) present a thick band. Extensive homology was found between G-banding patterns of Holochilus brasiliensis from Brazil and H. venezuelae. These facts support the hypothesis of a karyotypic evolution via centric fusions previously proposed for this genus.Key words: accessory chromosome, C- and G-banding, polymorphism, Holochilus venezuelae.

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Alaoui, N., J. Jordana und M. Ponsa. „A centric fission and heterochromatin polymorphism in Equus asinus Spanish breeds“. Journal of Animal Breeding and Genetics 121, Nr. 2 (April 2004): 135–41. http://dx.doi.org/10.1046/j.1439-0388.2003.00437.x.

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Babu, Arvind, und Ram S. Verma. „Characterization of human chromosomal constitutive heterochromatin“. Canadian Journal of Genetics and Cytology 28, Nr. 5 (01.10.1986): 631–44. http://dx.doi.org/10.1139/g86-093.

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The constitutive heterochromatin of human chromosomes is evaluated by various selective staining techniques, i.e., CBG, G-11, distamycin A plus 4,6-diamidino-2-phenylindole-2-HCl (DA/DAPI), the fluorochrome D287/170, and Giemsa staining following the treatments with restriction endonucleases AluI and HaeIII. It is suggested that the constitutive heterochromatin could be arbitrarily divided into at least seven types depending on the staining profiles expressed by different regions of C-bands. The pericentromeric C-bands of chromosomes 1, 5, 7, 9, 13–18, and 20–22 consist of more than one type of chromatin, of which chromosome 1 presents the highest degree of heterogeneity. Chromosomes 3 and 4 show relatively less consistent heterogeneous fractions in their C-bands. The C-bands of chromosomes 10, 19, and the Y do not have much heterogeneity but have characteristic patterns with other methods using restriction endonucleases. Chromosomes 2, 6, 8, 11, 12, and X have homogeneous bands stained by the CBG technique only. Among the chromosomes with smaller pericentric C-bands, chromosome 18 shows frequent heteromorphic variants for the size and position (inversions) of the AluI resistant fraction of C-band. The analysis of various types of heterochromatin with respect to specific satellite and nonsatellite DNA sequences suggest that the staining profiles are probably related to sequence diversity.Key words: polymorphism, heteromorphism, heterogeneity, banding, restriction endonucleases.

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Marciniak, Marcin, Malgorzata Lenartowicz, Aniela Golas und Jozefa Styrna. „Correlation of Centromeric Heterochromatin C-band Polymorphism with Breeding Failure in Mice“. Folia Biologica 58, Nr. 3 (30.06.2010): 251–55. http://dx.doi.org/10.3409/fb58_3-4.251-255.

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Sentis, C., J. Santos und J. Fernandez-Piqueras. „C-heterochromatin polymorphism in Baetica ustulata: intraindividual variation and fluorescence banding patterns“. Chromosoma 94, Nr. 1 (Juli 1986): 65–70. http://dx.doi.org/10.1007/bf00293531.

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RAMOS, ROSEMAR S. L., WILLIAM G. VALE und FÁTIMA L. ASSIS. „Karyotypic analysis in species of the genus Dasyprocta (Rodentia: Dasyproctidae) found in Brazilian Amazon“. Anais da Academia Brasileira de Ciências 75, Nr. 1 (März 2003): 55–69. http://dx.doi.org/10.1590/s0001-37652003000100007.

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A total of 30 animals of the genus Dasyprocta were cytogenetically studied. They belong to the following species: D. prymnolopha (N=20), D. leporina (N=6), D. fuliginosa (N=1) and Dasyprocta sp. (N=3) (Dasyproctidae, Hystricognathi). Cell suspensions were obtained by peripheral blood culture, besides bone marrow and spleen cells, from D. prymnolopha and D. leporina. The diploid number was 64/65 for all samples. The karyotypes showed similarity, and chromosomal polymorphism was not detected by Giemsa conventional staining and G banding. The constitutive heterochromatin distribution at the pericentromeric region of all the chromosomes was similar in all species. D. prymnolopha, D. leporina and Dasyprocta sp. presented variation in the heterochromatical block size at one of the homologues of the A18 pair. D. fuliginosa presented the heterochromatin uniformly distributed in all chromosomes. There was not variation in the NORs pattern in the species studied.

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de Oliveira, Luciene Castuera, Marcos Otávio Ribeiro, Gerlane de Medeiros Costa, Cláudio Henrique Zawadzki, Ana Camila Prizon-Nakajima, Luciana Andreia Borin-Carvalho, Isabel Martins-Santos und Ana Luiza de Brito Portela-Castro. „Cytogenetic characterization of Hypostomus soniae Hollanda-Carvalho & Weber, 2004 from the Teles Pires River, southern Amazon basin: evidence of an early stage of an XX/XY sex chromosome system“. Comparative Cytogenetics 13, Nr. 4 (11.12.2019): 411–22. http://dx.doi.org/10.3897/compcytogen.v13i4.36205.

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In the present study, we analyzed individuals of Hypostomus soniae (Loricariidae) collected from the Teles Pires River, southern Amazon basin, Brazil. Hypostomus soniae has a diploid chromosome number of 2n = 64 and a karyotype composed of 12 metacentric (m), 22 submetacentric (sm), 14 subtelocentric (st), and 16 acrocentric (a) chromosomes, with a structural difference between the chromosomes of the two sexes: the presence of a block of heterochromatin in sm pair No. 26, which appears to represent a putative initial stage of the differentiation of an XX/XY sex chromosome system. This chromosome, which had a heterochromatin block, and was designated proto-Y (pY), varied in the length of the long arm (q) in comparison with its homolog, resulting from the addition of constitutive heterochromatin. It is further distinguished by the presence of major ribosomal cistrons in a subterminal position of the long arm (q). The Nucleolus Organizer Region (NOR) had different phenotypes among the H. soniae individuals in terms of the number of Ag-NORs and 18S rDNA sites. The origin, distribution and maintenance of the chromosomal polymorphism found in H. soniae reinforced the hypothesis of the existence of a proto-Y chromosome, demonstrating the rise of an XX/XY sex chromosome system.

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Babicz, Marek, Barbara Danielak-Czech, Anna Kozubska-Sobocińska, Iwona Łuszczewska-Sierakowska, Agata Wawrzyniak, Agnieszka M. Grzebalska und Kinga Kropiwiec-Domańska. „Cytogenetic and molecular studies in conservation breeding of Pulawska breed pigs“. Medycyna Weterynaryjna 73, Nr. 7 (2017): 395–98. http://dx.doi.org/10.21521/mw.5725.

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The paper presents the genetic characteristics of Pulawska breed pigs carried out on the basis of cytogenetic and molecular studies. Among chromosome markers, polymorphic variants of specific chromosome structures such as centromeric heterochromatin areas (C bands) and nucleolar organizing regions (NOR bands) were taken into account. The described breed-specific tendencies concerning size polymorphism of these structures are the source of chromosome markers that are useful for identifying the linkage with genes controlling important production traits. On the other hand, molecular studies presented in this work included DNA markers of the STR and SNP type (with particular consideration of the PRL, FST, MC4R, TNNT3, MTTP and DIO3 genes), which are useful in determining the genetic background of functional traits, as well as the characteristics of the breeds for terms of genetic variation, especially conservative breeds, where it is appropriate to maintain the existing genetic diversity and intra-breed variability.

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Küçük, Halime, Yunus Aydin, Ebru Erzurumluoglu, Muhsin Özdemir, Hikmet Hassa und Sevilhan Artan. „The effects of a heterochromatin polymorphism in chromosome 6 on premature ovarian failure“. Asian Pacific Journal of Reproduction 4, Nr. 1 (März 2015): 41–43. http://dx.doi.org/10.1016/s2305-0500(14)60056-7.

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Rovatsos, Michail T., Juan A. Marchal, Ismael Romero-Fernández, Maria Arroyo, Eva B. Athanasopoulou und Antonio Sánchez. „Extensive Sex Chromosome Polymorphism of Microtus thomasi/Microtus atticus Species Complex Associated with Cryptic Chromosomal Rearrangements and Independent Accumulation of Heterochromatin“. Cytogenetic and Genome Research 151, Nr. 4 (2017): 198–207. http://dx.doi.org/10.1159/000477114.

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The sibling species Microtus thomasi and M. atticus represent probably the highest karyotypic diversity within the genus Microtus and are an interesting model for chromosomal evolution studies. In addition to variation in autosomes, they show a high intraspecific variation in the size and morphology of both sex chromosomes. We analyzed individuals with different sex chromosome constitutions using 3 painting probes, 2 from Y chromosome variants and 1 from the small arm of the submetacentric X chromosome. Our comparative painting approach uncovered 12 variants of Y and 14 variants of X chromosomes, which demonstrates that the polymorphism of sex chromosomes is substantially larger than previously reported. We suggest that 2 main processes are responsible for this sex chromosome polymorphism: change of morphology from acrocentric to submetacentric or metacentric chromosomes and increase in size due to accumulation of repetitive DNA sequences, generating heterochromatic blocks. Strong genetic drift in small and fragmented populations of these 2 species could be related to the origin and maintenance of the large polymorphism of sex chromosomes. We proposed that a similar polymorphism variation combined with random drift fixing the biggest sex chromosomes could have occurred in the origin of some of the actual Microtus species with giant sex chromosomes.

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Cerro, A. L. del, und J. L. Santos. „Synapsis in grasshopper bivalents heterozygous for centric shifts“. Genome 38, Nr. 3 (01.06.1995): 616–22. http://dx.doi.org/10.1139/g95-078.

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Analysis of surface-spread synaptonemal complexes of zygotene and pachytene spermatocytes was carried out on centric-shift heterozygotes of grasshoppers. These rearrangements affected the M7 chromosome in Chorthippus vagans and the M6 and S8 chromosomes in Chorthippus apricarius. The shifts in the latter two chromosomes were also associated with C-heterochromatin variations between homologous chromosomes. Rearranged chromosomes proceeded directly to heterosynapsis without an apparent intervening homosynaptic phase in M7 bivalents of Ch. vagans and M6 bivalents of Ch. apricarius. In the latter case, axial equalization of the heterochromatin polymorphism was also achieved. On the other hand, asynapsis of the intercentromeric regions throughout pachytene was the rule in the centric shift involving the S8 chromosome of Ch. apricarius. In the three cases analysed, the production of unbalanced gametes in the heterozygotes is precluded either by the lack of chiasma formation in heterosynapsed rearranged segments or by the lack of pairing between such segments. Chiasmata were limited to the homologous regions of the heteromorphic bivalents.Key words: synapsis, surface spreading, centric shift, chiasma distribution, meiosis.

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Vaghasia, Ketan K., Nidhi D. Shah, Parth S. Shah, Vidhi M. Bhatt, Sandip C. Shah und Mandava V. Rao. „KARYOTYPIC ANALYSIS OF CHROMOSOMAL POLYMORPHISM IN RELATION TO REPRODUCTIVE FAILURE“. International Journal of Pharmacy and Pharmaceutical Sciences 9, Nr. 4 (27.02.2017): 140. http://dx.doi.org/10.22159/ijpps.2017v9i4.15787.

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Objective: This study was undertaken to elucidate the role of heteromorphism in causation of reproductive anomalies like infertility.Methods: In our study, cytogenetic analysis of 830 suspected referral cases of both sexes were assessed using standard karyotypic technique with Giemsa staining from their blood samples. We identified heteromorphism of D/G groups and non-acrocentric chromosomes following WHO nomenclature.Results: Our data revealed that most of our heteromorphic cases (38;4.58%) were related to p arm satellites (ps+) of the chromosomes and are related to infertility and abortion. No significant gender variation was noticed in this study.Conclusion: We hence, suggest that heteromorphism is associated with a loss of reproductive function, as heterochromatin may contain genes that regulate cellular roles in reproduction. Further, it becomes important that such cases are considered for molecular studies, genetic counseling and prenatal/pre-implantation screening.

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Phillips, Ruth B., Kent M. Reed und Petr Ráb. „Revised karyotypes and chromosome banding of coregonid fishes from the Laurentian Great Lakes“. Canadian Journal of Zoology 74, Nr. 2 (01.02.1996): 323–29. http://dx.doi.org/10.1139/z96-040.

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Karyotypes of lake whitefish, Coregonus clupeaformis, and various Great Lakes cisco species, lake herring or cisco, C. artedi, bloater, C. hoyi, blackfin cisco, C. nigripinnis, and shortjaw cisco, C. zenithicus, were analyzed using Giemsa staining, C-banding, silver staining, and Chromomycin A3 fluorescence. Coregonus clupeaformis had a karyotype (2n = 80, NF = 98) indistinguishable from that described for C. laveretus from Europe, with one pair of nuclear organizer regions (NORs) on the short arms of a small acrocentric chromosome pair and a second NOR on the short arms of another acrocentric chromosome pair. This species displayed a size polymorphism involving the heterochromatic short arm of the largest metacentric–submetacentric pair. All four cisco species had similar karyotypes (2n = 80, NF = 98), with the exception of some C. artedi from Lake Superior, which were heterozygous for a chromosome fusion involving the NOR chromosomes (2n = 79). One NOR was located pericentromerically on the long arm of the second largest acrocentric chromosome and a second NOR on the short arms of another acrocentric chromosome pair in several individuals. C-banding revealed that the difference in chromosome morphology between lake whitefish and the ciscoes probably resulted from amplification of heterochromatin on the short arms of one pair of large submetacentric–metacentric chromosomes.

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WEIMARCK, ANNA. „Heterochromatin polymorphism in the rye karyotype as detected by the Giemsa C-banding technique“. Hereditas 79, Nr. 2 (12.02.2009): 293–300. http://dx.doi.org/10.1111/j.1601-5223.1975.tb01486.x.

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Solovyeva, Anna, Ivan Levakin, Evgeny Zorin, Leonid Adonin, Yuri Khotimchenko und Olga Podgornaya. „Transposons-Based Clonal Diversity in Trematode Involves Parts of CR1 (LINE) in Eu- and Heterochromatin“. Genes 12, Nr. 8 (25.07.2021): 1129. http://dx.doi.org/10.3390/genes12081129.

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Trematode parthenitae have long been believed to form clonal populations, but clonal diversity has been discovered in this asexual stage of the lifecycle. Clonal polymorphism in the model species Himasthla elongata has been previously described, but the source of this phenomenon remains unknown. In this work, we traced cercarial clonal diversity using a simplified amplified fragment length polymorphism (SAFLP) method and characterised the nature of fragments in diverse electrophoretic bands. The repetitive elements were identified in both the primary sequence of the H. elongata genome and in the transcriptome data. Long-interspersed nuclear elements (LINEs) and long terminal repeat retrotransposons (LTRs) were found to represent an overwhelming majority of the genome and the transposon transcripts. Most sequenced fragments from SAFLP pattern contained the reverse transcriptase (RT, ORF2) domains of LINEs, and only a few sequences belonged to ORFs of LTRs and ORF1 of LINEs. A fragment corresponding to a CR1-like (LINE) spacer region was discovered and named CR1-renegade (CR1-rng). In addition to RT-containing CR1 transcripts, we found short CR1-rng transcripts in the redia transcriptome and short contigs in the mobilome. Probes against CR1-RT and CR1-rng presented strikingly different pictures in FISH mapping, despite both being fragments of CR1. In silico data and Southern blotting indicated that CR1-rng is not tandemly organised. CR1 involvement in clonal diversity is discussed.

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Woznicki, Pawel, und Malgorzata Jankun. „Chromosome polymorphism of Atlantic salmon (Salmo salar) from the River Dzwina, Baltic Sea Basin: arm length and NOR location variation of the eighth chromosome“. Canadian Journal of Zoology 72, Nr. 2 (01.02.1994): 364–67. http://dx.doi.org/10.1139/z94-050.

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A population of Atlantic salmon from the River Dzwina was karyotyped using conventional staining and banding techniques. The chromosome number was 2n = 58, and the chromosome arm number (NF) was 74. Variation in the size of the long arm of the eighth chromosome pair was observed. The presence of constitutive heterochromatin on this arm was confirmed by C-banding. Silver banding revealed variability in the location of nucleolus organizer regions (NORs) on this arm. Four cytotypes and three phenotypes of the NOR-bearing chromosome were found. The polymorphism of the eighth metacentric pair of chromosomes observed in Atlantic salmon was probably due to deletion and paracentric inversion of the arm involved.

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HIRAI, Hirohisa, Yoshinori SHONO, G. Antonieta ROJAS de ARIAS und Isao TADA. „Constitutive heterochromatin polymorphism of a Triatoma infestans strain, a main vector insect of Chagas' disease“. Medical Entomology and Zoology 42, Nr. 4 (1991): 301–3. http://dx.doi.org/10.7601/mez.42.301.

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Garagna, Silvia, Maria Vittoria Civitelli, Nicola Marziliano, Riccardo Castiglia, Maurizio Zuccotti, Carlo Alberto Redi und Ernesto Capanna. „Genome size variations are related to X‐chromosome heterochromatin polymorphism inArvicanthissp. from Benin (West Africa)“. Italian Journal of Zoology 66, Nr. 1 (Januar 1999): 27–32. http://dx.doi.org/10.1080/11250009909356233.

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Movafagh, A., S. A. Mortazavi-Tabatabaei und A. A. Kolahi. „The role of α-satellite DNA and heterochromatin polymorphism in leukemia patients and illicit drug addicts“. Genetics and Molecular Research 10, Nr. 4 (2011): 3999–4005. http://dx.doi.org/10.4238/2001.november.25.3.

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Vicari, M. R., R. F. Artoni und L. A. C. Bertollo. „Heterochromatin polymorphism associated with 18S rDNA: a differential pathway among Hoplias malabaricus fish populations“. Cytogenetic and Genome Research 101, Nr. 1 (2003): 24–28. http://dx.doi.org/10.1159/000073413.

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Yan, Huihuang, Guoqing Liu, Zhukuan Cheng, Shaokai Min und Lihuang Zhu. „Characterization of euploid backcross progenies derived from interspecific hybrids between Oryza sativa and O. eichingeri by restriction fragment length polymorphism (RFLP) analysis and genomic in situ hybridization (GISH)“. Genome 44, Nr. 1 (01.02.2001): 86–95. http://dx.doi.org/10.1139/g00-086.

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Restriction fragment length polymorphism (RFLP) analysis and GISH (genomic in situ hybridization) were performed on euploid plants derived from crosses between Oryza sativa (2n = 24, AA) and two brown planthopper-resistant accessions of O. eichingeri (2n = 24, CC). After screening with 164 RFLP markers, 60 of the 67 euploid plants were identified as introgression lines, each carrying 16 small O. eichingeri segments integrated on chromosomes 1, 2, 6, or 10. In the somatic chromosome preparations of F1 hybrid, O. eichingeri chromosomes, fluorescing greenish-yellow in the sequential GISH, appeared to be longer and to contain more heterochromatin than O. sativa ones, and this karyotypic polymorphism can be used to detect some introgressed O. eichingeri segments in euploid plants. In addition, GISH identification presented direct evidence for the transfer of small segments from O. eichingeri to O. sativa chromosome(s) which were subsequently recognized according to their condensation pattern, arm ratio, and chromosome length. The present results would contribute to the molecular mapping and selection of O. eichingeri - derived brown planthopper-resistant gene and positive yield QTLs.Key words: Oryza sativa, Oryza eichingeri, introgression lines, RFLP, genomic in situ hybridization (GISH).

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Kantek, Daniel Luis Zanella, Rafael Bueno Noleto, Alberto Sérgio Fenocchio und Marta Margarete Cestari. „Cytotaxonomy, heterochromatic polymorphism and natural triploidy of a species of Astyanax (Pisces, Characidae) endemic to the Iguaçu river basin“. Brazilian Archives of Biology and Technology 50, Nr. 1 (Januar 2007): 67–74. http://dx.doi.org/10.1590/s1516-89132007000100008.

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Cytogenetic analysis with Astyanax sp. D revealed a karyotype of 2n=50 with 2M+26SM+6ST+16A, besides a triploid specimen showing 2n=75 chromosomes (3M+39SM+9ST+24A). C-banding strongly stained the terminal regions of several SM-ST-A chromossomes. Two pairs of acrocentric chromosomes presented interstitial heterochromatin, this state being polymorphic and occuring due to possible paracentric inversions. The results obtained with the AluI restriction enzyme and A3 chromomycin were similar to the C-banding. Relationships were proposed between Astyanax sp. D and A. scabripinnis, as well as considerations for a possible origin of the triploid specimen (2n=3x=75). When comparing the present results with cytogenetic features of other endemic Astyanax species in the Iguaçu river (A. sp. B and C), a clear differentiation was observed between them, indicating cytogenetics as an important cytotaxonomic tool.

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Alvarez, W. Trillo, J. J. Molina Acosta, J. A. Medina Suarez, A. Z. Escalante Mercado und C. R. Ibañez Escalante. „Association between heterochromatin polymorphism 46, XX 9QH+ and multiple sclerosis (MS) with systemic lupus erythematosus (SLE). Case report“. Journal of the Neurological Sciences 405 (Oktober 2019): 90. http://dx.doi.org/10.1016/j.jns.2019.10.939.

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Вейко, Н. Н., Е. С. Ершова, М. С. Конькова, Е. М. Малиновская und С. В. Костюк. „Quantitative polymorphism of tandem repeats as a method of epigenetic regulation of the of human cells response to oxidative stress“. Nauchno-prakticheskii zhurnal «Medicinskaia genetika», Nr. 12(221) (28.12.2020): 68–70. http://dx.doi.org/10.25557/2073-7998.2020.12.68-70.

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Пространственная организация хроматина важна для нормального функционирования клетки. На архитектуру ядра влияют размеры отдельных фрагментов генома, которые коррелируют с числом копий этих фрагментов. Перемещение локусов 1q12 от поверхности ядра в центральные области является ключевой стадией адаптивного ответа клетки на стресс. Мы предположили, что размер локусов 1q12, который коррелирует с содержанием повтора f-SatIII, может влиять на перемещение этих участков хроматина в ядре. Методом FISH на выделенных лимфоцитах показали, что в контроле локусы 1q12 расположены вблизи поверхности ядра, в ядрах лимфоцитов больных шизофренией (БШ) и облученных контрольных клеток локусы 1q12 расположены в центральных районах ядра. Длительное культивирование облученных лимфоцитов сопровождалось гибелью клеток, и снижением содержания f-SatIII в ДНК. Очевидно, что погибали клетки с большим размером 1q12 (много f-SatIII), обогащая популяцию клетками с низким содержанием f-SatIII. В клетках БШ и в облученных клетках мы обнаружили повышение уровня РНК SATIII. Размеры гетерохроматина 1q12 в клетках человека могут влиять на процессы пролиферации и ответа клетки на стресс. Количественный полиморфизм тандемных повторов генома - один из эпигенетических механизмов регуляции ответа клеток на окислительный стресс. The spatial organization of chromatin is important for the normal functioning of the cell. Genome repeat cluster sizes can affect the chromatin spatial configuration and function. The 1q12 heterochromatin loci movement from the periphery to the center of the nucleus is the cells’ universal response to various types of stress. We hypothesized that a large 1q12 domain could affect chromatin movement, thereby inhibiting adaptive response (AR). Using the FISH method, we shown that in the control, 1q12 loci are located near the surface of the nucleus; in the lymphocyte nuclei of schizophrenic patients and irradiated control cells, 1q12 loci are located in the central regions of the nucleus. During prolonged cultivation, the irradiated cells with a large Large f-SatIII amount die and the population is enriched with the cells with low f-SatIII content. In intact SZ patients’ lymphocytes and in irradiated cells we found an increase in SATIII RNA levels. The size of heterochromatin 1q12 loci in human cells can affect to the proliferation and cells’ adaptive response to stress. Quantitative polymorphism of tandem genome repeats is one of the epigenetic mechanisms of genome expression’s regulation.

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Cuadrado, A., N. Jouve und C. Ceoloni. „Variation in highly repetitive DNA composition of heterochromatin in rye studied by fluorescence in situ hybridization“. Genome 38, Nr. 6 (01.12.1995): 1061–69. http://dx.doi.org/10.1139/g95-142.

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The molecular characterization of heterochromatin in six lines of rye has been performed using fluorescence in situ hybridization (FISH). The highly repetitive rye DNA sequences pSc 119.2, pSc74, and pSc34, and the probes pTa71 and pSc794 containing the 25S–5.8S–18S rDNA (NOR) and the 5S rDNA multigene families, respectively, were used. This allowed the individual identification of all seven rye chromosomes and most chromosome arms in all lines. All varieties showed similar but not identical patterns. A standard in situ hybridization map was constructed following the nomenclature system recommended for C-bands. All FISH sites observed appeared to correspond well with C-band locations, but not all C-banding sites coincided with hybridization sites of the repetitive DNA probes used. Quantitative and qualitative differences between different varieties were found for in situ hybridization response at corresponding sites. Variation between plants and even between homologous chromosomes of the same plant was found in open-pollinated lines. In inbred lines, the in situ pattern of the homologues was practically identical and no variation between plants was detected. The observed quantitative and qualitative differences are consistent with a corresponding variation for C-bands detected both within and between cultivars.Key words: fluorescence in situ hybridization, repetitive DNA, rye, Secale cereale, polymorphism.

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Pavet, Valeria, Cristián Quintero, Nicolás M. Cecchini, Alberto L. Rosa und María E. Alvarez. „Arabidopsis Displays Centromeric DNA Hypomethylation and Cytological Alterations of Heterochromatin Upon Attack by Pseudomonas syringae“. Molecular Plant-Microbe Interactions® 19, Nr. 6 (Juni 2006): 577–87. http://dx.doi.org/10.1094/mpmi-19-0577.

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Plant tissues display major alterations upon the perception of microbial pathogens. Changes of cytoplasmic and apo-plastic components that sense and transduce plant defenses have been extensively characterized. In contrast, less information is available about modifications affecting the plant nuclear genome under these circumstances. Here, we investigated whether the Arabidopsis thaliana DNA methylation status is altered in tissues responding to the attack of Pseudomonas syringae pv. tomato DC3000. We applied amplified fragment length polymorphism analysis to monitor cytosine methylation at anonymous 5′-CCGG-3′ and 5′-GATC-3′ sites in naïve and infected samples. Plant genomic fragments reducing methylation upon infection, including peri/centromeric repeats such as the 180-bp unit, Athila retrotansposon, and a portion of the nuclear insertion of mitochondrial DNA, were isolated and characterized. P. syringae pv. tomato-induced hypomethylation was detected by high-performance liquid chromatography assays and at the molecular level it did not seem to equally affect all 5-methyl cytosine (5-mC) residues. Nuclei from challenged tissues displayed structural chromatin alterations, including loosening of chromocenters, which also were stimulated by avirulent P. syringae pv. tomato, but not by the P. syringae pv. tomato hrpL¯ mutant. Finally, P. syringae pv. tomato-induced hypomethylation was found to occur in the absence of DNA replication, suggesting that it involves an active demethylation mechanism. All these responses occurred at 1 day postinfection, largely preceding massive plant cell death generated by pathogen attack.

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