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Journal articles on the topic 'Chromosome polymorphism'
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1
Taran Kyzy, Jafar Aliyev. "Value heterochromatin and polymorphic varian gene folat cycle in women with miscarried and losses of pregnancy." HEALTH OF WOMAN, no. 9(115) (November 30, 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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Nishioka, Yutaka. "Two types of mouse (Mus musculus domesticus) Y chromosomes in Quebec." Genome 35, no. 3 (June 1, 1992): 534–37. http://dx.doi.org/10.1139/g92-078.
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A Y chromosomal repetitive sequence identified two types of Y chromosomes in mice (Mus musculus domesticus) caught near Ste. Anne de Bellevue, Quebec. One type is apparently identical to the Y chromosome found in Maryland, Delaware, and California, whereas the other type is similar, but not identical, to the Y chromosome present in M.m. poschiavinus, an Alpine race of M.m. domesticus. These findings suggest that the domesticus Y chromosome is highly polymorphic and thus useful for elucidating the relationships among American and European house mouse populations.Key words: mouse Y chromosome, polymorphism, Mus musculus domesticus, repetitive sequence, Quebec.
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Angelova, Lyudmila, Maria Tsvetkova, and Mariya Levkova. "CHROMOSOMAL POLYMORPHISM IN BULGARIAN PATIENTS WITH REPRODUCTIVE PROBLEMS – ONE GENETIC CENTRE EXPERIENCE." Journal of IMAB - Annual Proceeding (Scientific Papers) 27, no. 4 (December 2, 2021): 4133–38. http://dx.doi.org/10.5272/jimab.2021274.4133.
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Chromosomal polymorphism is described as normal variants at chromosomal regions with no impact on the phenotype but a possible correlation to infertility and recurrent spontaneous abortions. The aim of this study was to evaluate the effect of the chromosomal polymorphisms involved in families with reproductive failures in the Bulgarian population. Material and methods: A total of 1733 patients with unexplained reproductive failures who visited the Laboratory of Medical Genetics – Varna, Bulgaria, (2004 - 2019) were investigated by conventional cytogenetic analysis GTG and CBG differential banding techniques and analyzed at the resolution 400-550 GTG bands. Results: Chromosomal polymorphisms were found in 173 infertile patients (9,98%). The sex distribution was 6,52% males and 3,46% females. The most frequent finding was inv(9)(qh) (23,7%). The other chromosomal variants, which were found, consisted: 9qh+/- variants (15,1%); polymorphisms on the short arms of the acrocentric chromosomes (21,4%); 16qh+ (12,7%) and 1qh+ (6,9%). Y chromosome polymorphism was found in 27,4% of the males with polymorphisms. Two rare cases of polymorphism involving the centromere regions - 19qcenh+ and 20pcenh+ were also found. Conclusion: There is growing evidence that polymorphisms may have a clinical impact on fertility and could take part in the etiology of RF. In this study, we found a significantly high percentage of polymorphisms (9,98%) among the tested patients, and they were more common among males. The statistical significance of increased incidence of chromosome variations found in our study emphasizes the need for routine evaluation of their role in families with RF in our country.
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Hatsumi, Machiko. "Karyotype polymorphism in Drosophila albomicans." Genome 29, no. 3 (June 1, 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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Mukhopadhyay, Saswati, Sujoy Dasgupta, Kushagradhi Ghosh, and Tania Mukherjee. "Investigating the relation between chromosomal polymorphism and recurrent pregnancy loss: A cohort study." Indian Journal of Obstetrics and Gynecology Research 9, no. 3 (August 15, 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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Rovatsos, Michail T., Juan A. Marchal, Ismael Romero-Fernández, Maria Arroyo, Eva B. Athanasopoulou, and 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, no. 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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Hashimoto, Diogo Teruo, and Fábio Porto-Foresti. "Chromosome polymorphism of heterochromatin and nucleolar regions in two populations of the fish Astyanax bockmanni (Teleostei: Characiformes)." Neotropical Ichthyology 8, no. 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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HENRIKSSON, J., J. C. DUJARDIN, C. BARNABÉ, S. BRISSE, G. TIMPERMAN, J. VENEGAS, U. PETTERSSON, M. TIBAYRENC, and A. SOLARI. "Chromosomal size variation in Trypanosoma cruzi is mainly progressive and is evolutionarily informative." Parasitology 124, no. 3 (March 2002): 277–86. http://dx.doi.org/10.1017/s0031182001001093.
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The evolutionary significance of chromosome size polymorphism was explored in a representative panel of 26 Trypanosoma cruzi stocks. We tested a progressive model (aCSDI) assuming that the larger the size difference between homologous chromosomes, the more divergent the parasites are. This was contrasted with a non-progressive model (Jaccard's distance), in which any chromosome size difference has the same weight. ACSDI-based dendrograms were very similar to those built-up from multilocus enzyme electrophoresis (MLEE) and random amplified polymorphic DNA (RAPD) data: structuring in 2 major lineages (T. cruzi I and T. cruzi II) and 5 small subdivisions within T. cruzi II was identical, and branching was very similar. Furthermore, a significant correlation (P<0·001) was observed between aCSDI and phenetic distances calculated from MLEE and RAPD data. In contrast, analysis of chromosome size polymorphism with Jaccard's distance generated dendrograms with relatively long branches, causing most branching points to cluster close together, which generates statistically uncertain branching points. Our results thus support a model of progressive chromosome size-variation and show that despite an extensive polymorphism, chromosomal sizes constitute valuable characters for evolutionary analyses. Furthermore, our data are consistent with the clonal evolution model previously proposed for T. cruzi.
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Vieira, Cristina P., Paula A. Coelho, and Jorge Vieira. "Inferences on the Evolutionary History of theDrosophila americanaPolymorphicX/4Fusion From Patterns of Polymorphism at theX-LinkedparalyticandelavGenes." Genetics 164, no. 4 (August 1, 2003): 1459–69. http://dx.doi.org/10.1093/genetics/164.4.1459.
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AbstractIn Drosophila there is limited evidence on the nature of evolutionary forces affecting chromosomal arrangements other than inversions. The study of the X/4 fusion polymorphism of Drosophila americana is thus of interest. Polymorphism patterns at the paralytic (para) gene, located at the base of the X chromosome, suggest that there is suppressed crossing over in this region between fusion and nonfusion chromosomes but not within fusion and nonfusion chromosomes. These data are thus compatible with previous claims that within fusion chromosomes the amino acid clines found at fused1 (also located at the base of the X chromosome) are likely maintained by local selection. The para data set also suggests a young age of the X/4 fusion. Polymorphism data on para and elav (located at the middle region of the X chromosome) suggest that there is no population structure other than that caused by the X/4 fusion itself. These findings are therefore compatible with previous claims that selection maintains the strong association observed between the methionine/threonine variants at fused1 and the status of the X chromosome as fused or unfused to the fourth chromosome.
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Zolan, M. E., N. K. Heyler, and N. Y. Stassen. "Inheritance of chromosome-length polymorphisms in Coprinus cinereus." Genetics 137, no. 1 (May 1, 1994): 87–94. http://dx.doi.org/10.1093/genetics/137.1.87.
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Abstract We have investigated the inheritance of chromosome-length polymorphisms in the basidiomycete Coprinus cinereus. The electrophoretic karyotypes of interfertile strains of C. cinereus are strikingly different, and crosses between strains with different karyotypes yield progeny with chromosomes of new sizes. Repeated backcrossing of a mutant to one parent often stabilizes the mutant chromosome at a unique size; this then becomes a chromosome-length polymorphism marker for that mutant gene. A comparison of mutant strains, their wild-type progenitor, and backcrossed strains revealed that these marker chromosomes are not caused by the initial mutagenic treatment and are found only in progeny of crosses between strains with polymorphic chromosomes. Thus, they are most likely formed by meiotic recombination. For the rad12 gene, the marker chromosome can further recombine to become the size of the homolog of the backcross parent. For the rad3 gene, both ectopic and homologous recombination events are likely involved in the generation of the marker chromosomes. As predicted by a recombination model, a cross to a new wild-type parent can change the size of a mutant marker chromosome. Therefore, changes in chromosome length are a common and prominent feature of the genome of this sexual fungus, and a variety of karyotypes is tolerated by the organism.
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Wei, Jun-Zhi, William F. Campbell, and Richard R. C. Wang. "Standard Giemsa C-banded karyotype of Russian wildrye (Psathyrostachys juncea) and its use in identification of a deletion–translocation heterozygote." Genome 38, no. 6 (December 1, 1995): 1262–70. http://dx.doi.org/10.1139/g95-166.
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Ten accessions of Russian wildrye, Psathyrostachys juncea (Fisch.) Nevski (2n = 2x = 14; NsNs), collected from different geographical regions were analyzed using the C-banding technique. C-banding pattern polymorphisms were observed at all levels, i.e., within homologous chromosome pairs of the same plant, among different individuals within accessions, between different accessions of the same geographic area, and among accessions of different origins. The seven homologous groups varied in the level of C-banding pattern polymorphism; chromosomes A, B, E, and F were more variable than chromosomes C, D, and G. The polymorphisms did not hamper chromosome identification in Ps. juncea, because each chromosome pair of the Ns genome had a different basic C-banding pattern and karyotypic character. A standard C-banded karyotype of Ps. juncea is proposed based on the overall karyotypes and C-bands in the 10 accessions. The C-bands on the Ns-genome chromosomes were designated according to the rules of nomenclature used in wheat. A deletion–translocation heterozygote of Russian wildrye was identified based on the karyotype and C-banding patterns established. The chromosome F pair consisted of a chromosome having the distal segment in the long arm deleted and a translocated chromosome having the distal segment of long arm replaced by the distal segment of the long arm of chromosome E. The chromosome E pair had a normal chromosome E and a translocated chromosome having the short arm and the proximal segment of the long arm of chromosome E and the distal segment of the long arm of chromosome F.Key words: Psathyrostachys juncea, karyotype, Giemsa C-banding, polymorphism, B chromosome.
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Shankar C., Abida P. S., Jiji Joseph, Rose Mary Francies, Deepu Mathew, and Beena R. "Evaluation for Parental Polymorphism and Identification of Microsatellites Linked to Drought Tolerance in Rice (Oryza sativa L.)." International Journal of Plant & Soil Science 35, no. 22 (November 21, 2023): 275–84. http://dx.doi.org/10.9734/ijpss/2023/v35i224134.
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Aims: To identify the ready-to-use polymorphic microsatellite markers associated with drought tolerance for marker-assisted backcross breeding through a polymorphism survey between Jyothi and Chuvannamodan rice varieties.
Place and Duration of Study: Centre for plant biotechnology and molecular biology, Thrissur, Kerala, India, during January to May 2023.
Methodology: The genomic DNA of Jyothi and Chuvannamodan was isolated by following CTAB (Cetyltrimethyl Ammonium Bromide) method with modification. Isolated DNA from both varieties was subjected to PCR amplification using 208 Simple Sequence Repeats (SSRs) primer pairs distributed in 12 chromosomes. The amplified PCR products were electrophoresed in 3% agarose gel and separated fragments were visualized and documented in the Gel Documentation System. Different allele sizes produced by the same SSRs primers between two varieties are identified as polymorphic markers. Polymorphism per-cent was calculated, and frequency distribution and chromosome distribution of polymorphic markers were analyzed.
Results: A total of 208 SSR primers were surveyed for the parental polymorphism. Out of which, 85 SSR primers exhibited clear polymorphism between Jyothi and Chuvannamodan and the remaining 123 were monomorphic primers. The amplicon size ranged from 83bp (RM430) to 495bp (RM18919) among the different primers. The survey revealed maximum parental polymorphism on chromosome 4 (69.23%), followed by chromosome 5 (64.28%), and minimum polymorphism on chromosome 8 (21.73%). The average per cent of polymorphism between the parents was 40.86%. Among the 85 polymorphic markers, 66 had dinucleotide repeats, 17 had trinucleotide repeats, and 1 had tetranucleotide repeats.
Markers with dinucleotide repeats showed higher level of polymorphism. A group of 28 polymorphic markers were identified to be linked with traits including root-related traits, grain yield, leaf rolling and leaf drying under drought conditions.
Conclusion: The polymorphic markers identified in the present study form the basis for tagging drought-tolerant QTLs/genes, fine mapping of those genes, and subsequently in marker-assisted breeding programs. The polymorphic markers linked with the QTLs for grain yield under drought can be pyramided in Jyothi through marker-assisted backcross breeding.
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Kaiser, P. E., J. A. Seawright, and B. K. Birky. "Chromosome polymorphism in natural populations of Anopheles quadrimaculatus Say species A and B." Genome 30, no. 2 (April 1, 1988): 138–46. http://dx.doi.org/10.1139/g88-024.
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Ovarian polytene chromosomes from eight populations of Anopheles quadrimaculatus in the southeastern United States were observed for chromosomal polymorphisms. Two sibling species, species A and B, each with intraspecific inversions, were distinguished. Species A correlates with the previously published standard maps for salivary gland and ovarian nurse-cell polytene chromosomes. Species A was found at all eight collection sites, and five of these populations also contained species B. Three inversions on the right arm of chromosome 3 were observed in species A. Species B contained a fixed inversion on the X chromosome, one fixed and one floating inversion on the left arm of chromosome 2, and one fixed and one floating inversion on the right arm of chromosome 3. The fixed inversion on the X chromosome makes this the best diagnostic chromosome for distinguishing species A and B. An unusual dimorphism in the left arm of chromosome 3, found in both species A and B, contained two inversions. The heterokaryotypes, as well as two distinct homokaryotypes, were seen in all of the field populations. Intraspecific clinal variations in the frequencies of the species A inversions were noted. The Florida populations were practically devoid of inversions, the Georgia and Alabama populations contained some inversions, and the Arkansas population was mostly homozygous for two of the inversions. The phylogenetic relationships of species A and B to the Maculipennis complex (Nearctic) are discussed.Key words: Anopheles, inversion, populations, chromosome polymorphism, phylogenetics.
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DUJARDIN, J. C., A. L. BAÑULS, J. P. DUJARDIN, J. AREVALO, M. TIBAYRENC, and D. LE RAY. "Comparison of chromosome and isoenzyme polymorphism in geographical populations of Leishmania (Viannia) peruviana." Parasitology 117, no. 6 (December 1998): 547–54. http://dx.doi.org/10.1017/s0031182098003357.
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Five chromosomes and 17 isoenzyme loci were analysed in 4 allopatric populations of Leishmania (Viannia) peruviana, and molecular distances calculated with 2 estimators, Chromosomal Size Difference Index and Jaccard Distance. Chromosome and isoenzyme data were in overall concordance: 13/30 isolates clustered similarly on the dendrograms constructed from the different estimators, and a significant correlation (P<0·001) was observed between the molecular distances calculated from the two sets of characters. This indicates an evolutionary association between chromosomal size polymorphism and isoenzymes. Chromosomes have a faster molecular clock than isoenzymes; twice as many genotypes were identified by chromosome analysis and significant size differences (for a total of up to 500 kb for 5 chromosomes together) were observed within a given zymodeme. Chromosomes most likely represent better indicators of genetic drift than isoenzymes, as suggested by the higher correlation between both estimators of chromosomal size-polymorphism and eco-geography. Some chromosomes might present an adaptive response to environmental variation.
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Mariotto, Sandra, Liano Centofante, Carlos S. Miyazawa, Luiz Antonio Carlos Bertollo, and Orlando Moreira Filho. "Chromosome polymorphism in Ancistrus cuiabae Knaack, 1999 (Siluriformes: Loricariidae: Ancistrini)." Neotropical Ichthyology 7, no. 4 (2009): 595–600. http://dx.doi.org/10.1590/s1679-62252009000400006.
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Cytogenetic and FISH analyses were performed in 30 Ancistrus cuiabae specimens from a bay near the town of Poconé, in the Pantanal of Mato Grosso, Brazil. The observed diploid number was 2n = 34 chromosomes for both sexes and three distinct katyotypic formulae were found, namely cytotype A (20m, 8sm, 6st, Fundamental Number/FN = 68; 6 males and 11 females), cytotype B (19m, 8sm, 6st, 1a, FN = 67; 8 males and 4 females) and cytotype C (18m, 8sm, 6st, 2a, FN = 66; a single male). NORs's analyses showed that these regions were located in distinct sites on the NOR-bearing chromosome pair, according to cytotypes. Thus, in cytotype A, NORs were located in the terminal region of the short arm of the second metacentric chromosome pair; in cytotype B, they were detected in the short arm of the metacentric chromosome and interstitially on the acrocentric chromosome and, in cytotype C, NORs were observed in the interstitial region of the acrocentric chromosome pair. C-positive heterochromatic bands were adjacent to the rDNA sites in the corresponding chromosomes. Thus, the chromosomal polymorphism of A. cuiabae was probably originated through a pericentric inversion in chromosome pair nº 2 involving the NOR sites, which represents a novelty in the Ancistrini tribe. The results also broaden the knowledge of the chromosomal evolution in Ancistrus, the most derived genus of the Ancistrini tribe.
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Valeri, Mirela P., Iara M. Tomazella, and José M. B. Duarte. "Intrapopulation Chromosomal Polymorphism in Mazama gouazoubira (Cetartiodactyla; Cervidae): The Emergence of a New Species?" Cytogenetic and Genome Research 154, no. 3 (2018): 147–52. http://dx.doi.org/10.1159/000488377.
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Mazama gouazoubira is a small deer species widely distributed in South America. Previous studies have shown that this species presents intraspecific chromosomal polymorphisms, which could affect fertility due to the effects of chromosomal rearrangements on gamete formation. Important aspects regarding the karyotype evolution of this species and the genus remain undefined due to the lack of information concerning the causes of this chromosomal variation. Nineteen individuals belonging to the Mazama gouazoubira population located in the Pantanal were cytogenetically evaluated. Among the individuals analyzed, 9 had B chromosomes and 5 carried a heterozygous centric fusion (2n = 69 and FN = 70). In 3 individuals, the fusion occurred between chromosomes X and 16, in 1 individual between chromosomes 7 and 21, and in another individual between chromosomes 4 and 16. These striking polymorphisms could be explained by several hypotheses. One is that the chromosome rearrangements in this species are recent and not fixed in the population yet, and another hypothesis is that they represent a balanced polymorphism and that heterozygotes have an adaptive advantage. On the other hand, these polymorphisms may negatively influence fertility and raise questions about sustainability or reproductive isolation of the population.
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Kam-Morgan, L. N. W., B. S. Gill, and S. Muthukrishnan. "DNA restriction fragment length polymorphisms: a strategy for genetic mapping of D genome of wheat." Genome 32, no. 4 (August 1, 1989): 724–32. http://dx.doi.org/10.1139/g89-503.
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The use of restriction fragment length polymorphisms (RFLPs) as genetic markers in bread wheat, Triticum aestivum, and a wild wheat progenitor, Aegilops squarrosa, was investigated. The objectives were (i) to identify RFLP loci; (ii) to assign cDNA sequences onto specific chromosomes and chromosome arms; and (iii) to determine linkage relationships between RFLP loci. A low level of polymorphism was found, utilizing barley cDNA clones as probes, in hexaploid cultivated wheats. However, accessions of A. squarrosa revealed greater polymorphism. Wheat–barley alien addition lines were used to assign 17 cDNA sequences to specific chromosome groups and ditelosomic and nullisomic–tetrasomic wheat stocks were used to assign these sequences to specific chromosome arms. Of 16 sets of RFLP loci, excluding α-Amy-1 and α-Amy-2, 14 are new sets of loci marking 6 of the 7 homoeologous groups of wheat. The construction of a linkage map of chromosome 5D was initiated by analyzing a segregating F2 population between two homozygous accessions of A. squarrosa. A strategy using wheat aneuploids for chromosome arm location and a segregating A. squarrosa population for linkage measurement was demonstrated for mapping the D-genome chromosomes of wheat.Key words: genetic map, restriction fragment length polymorphisms, Triticum aestivum, Aegilops squarrosa, polyploidy.
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Cabrero, Josefa, and Juan Pedro M. Camacho. "Population cytogenetics of Chorthippus vagans. I. Polymorphisms for pericentric inversion and for heterochromatin deletion." Genome 29, no. 2 (April 1, 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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Campenhout, S. Van, R. Aert, and G. Volckaert. "Orthologous DNA sequence variation among 5S ribosomal RNA gene spacer sequences on homoeologous chromosomes 1B, 1D, and 1R of wheat and rye." Genome 41, no. 2 (April 1, 1998): 244–55. http://dx.doi.org/10.1139/g98-016.
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5S ribosomal gene spacer sequences from the short-spacer arrays of wheat and rye were isolated by PCR. The 29 new DNA sequences displayed noticeable heterogeneity at scattered positions. Nevertheless, based on shared DNA sequence polymorphisms, sequence alignment clearly classified the sequences into three groups. Group-specific primer sets were designed to allow chromosomal assignment by PCR on nullitetrasomic wheat stocks, as well as on wheat-rye translocation and addition lines. The three groups were assigned to orthologous loci 5S-Rrna-B1, 5S-Rrna-D1, and 5S-Rrna-R1 on homoeologous chromosomes 1B, 1D, and 1R, respectively. Hence, group-specific DNA sequence variation could be related to fixed orthologous DNA sequence variation between 5S rRNA multigene families on the homoeologous group 1 chromosomes. In addition, members of the three groups showed fixed orthologous length polymorphism. Four sequenced 5S-Rrna-B1 units, however, had a duplication in the gene encoding region and are probably representatives of a nontranscribed subfamily of 5S rDNA repeating units. The observed chromosome-specific polymorphisms among sequences belonging to a multigene family with thousands of copies suggests that this type of polymorphism may exist in many genes and gene families in polyploid wheats. The implication of this finding in relation to the construction of molecular tools for wheat-genome analysis and manipulation is discussed.Key words: 5S ribosomal RNA loci, nontranscribed spacer, chromosome location, PCR markers, wheat-rye translocation.
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Oliveira, Kelly Cristina de, Bianca Bianco, Ieda T. N. Verreschi, Alexis Dourado Guedes, Bianca Borsato Galera, Marcial Francis Galera, Caio P. Barbosa, and Monica Vannucci Nunes Lipay. "Prevalence of the polymorphism MTHFR A1298C and not MTHFR C677T is related to chromosomal aneuploidy in Brazilian Turner Syndrome patients." Arquivos Brasileiros de Endocrinologia & Metabologia 52, no. 8 (November 2008): 1374–81. http://dx.doi.org/10.1590/s0004-27302008000800028.
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BACKGROUND: Dysfunctions in the folate metabolism can result in DNA hypomethylation and abnormal chromosome segregation. Two common polymorphisms of this enzyme (C677T and A1298C) reduce its activity, but when associated with aneuploidy studies the results are conflicting. The objective of the present study is to analyze the MTHFR gene polymorphisms in women with Turner Syndrome and in a control group, correlating the findings to the chromosomal aneuploidy. METHODS: The study comprised 140 patients with Turner Syndrome, of which 36 with chromosome mosaicism and 104 non-mosaics, and a control group of 209 fertile and healthy women without a history of any offspring with aneuploidy. Polymorphisms C677T and A1298C were studied by RFLP-PCR and the results were statistically analyzed. RESULTS: The frequency of genotypes MTHFR 677CC, 677CT and 677TT in the patients with Turner Syndrome and chromosome mosaicism was, respectively, 58.3%, 38.9% and 2.8%. Among the patients with non-mosaic Turner Syndrome, 47.1% presented genotype 677CC, 45.2% genotype 677CT, and 7.7% genotype 677TT. Among the 209 individuals of the control group, genotypes 677CC, 677CT and 677TT were found at the following frequencies: 48.3%, 42.1% and 9.6%, respectively. As for polymorphism A1298C, the patients with Turner Syndrome and chromosome mosaicism presented genotypes 1298AA, 1298AC and 1298CC at the following frequencies: 58.3%, 27.8% and 13.9%, respectively. Among the non-mosaic Turner Syndrome patients, genotype 1298AA was found in 36.5%, genotype 1298AC in 39.4%, and genotype 1298CC in 22.1%. In the control group, genotypes 1298AA, 1298AC and 1298CC were present at the following frequencies: 52.6%, 40.7% and 6.7%, respectively. CONCLUSION: No correlation was observed between the MTHFR gene polymorphism 677 and chromosomal aneuploidy in the Turner Syndrome patients. However, the MTHFR gene polymorphism at position 1298, mainly genotype 1298CC that reduces the enzyme efficiency, was more frequent in the group of Turner Syndrome patients, suggesting its involvement in mechanisms related to chromosomal imbalances.
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Ayala, Francisco J., Luis Serra, and Antonio Prevosti. "A grand experiment in evolution: the Drosophila subobscura colonization of the Americas." Genome 31, no. 1 (January 1, 1989): 246–55. http://dx.doi.org/10.1139/g89-042.
Full textAbstract:
Drosophila subobscura is a Palearctic species that has been extensively studied by population and evolutionary geneticists for nearly half a century. In 1978, it appeared in Puerto Montt, Chile; within a few years it extended over much of Chile and into Argentina and became the most common drosophilid in many places. In 1982, it appeared in the American northwest; shortly thereafter it was found extensively distributed from southern British Columbia, through Washington and Oregon, into southern California, west of Sierra Nevada. In North America also it has become a common drosophilid in many places. The source of the colonizers has been sought with four lines of research: sequence arrangement of the polytene chromosomes, allozyme polymorphisms, mitochondrial DNA restriction patterns, and frequency of lethal alleles. The origin of the colonizers remains uncertain, although all evidence indicates that both the North American and the South American colonizers derive from the same Palearctic population. The overall configuration of the chromosomal and allozyme frequencies suggests a western Mediterranean origin, which is consistent with the mtDNA data. The presence of a particular chromosome arrangement, O5, suggests a northern European origin. Lethal allelism has opened up the possibility of discovering the precise origin of the colonizers: all O5 chromosomes in the Americas carry a particular recessive lethal gene. There is strong evidence that the number of founders was not very small and not very large, perhaps between 10 individuals and several score. The chromosomal polymorphisms of D. subobscura exhibit well-defined latitudinal clines in the Old World. In the few years since the colonization, clines in every chromosome have evolved in the Americas that have identical latitudinal polarity with those in the Old World. This would seem strong evidence that the polymorphisms and the clines are adaptive.Key words: chromosomal polymorphism, mitochondrial DNA evolution, allozyme polymorphism, lethal allelism, adaptation, geographic clines.
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Sinthuwiwat, Thivaratana, Phanasit Poowasanpetch, Angsana Wongngamrungroj, Kamonwan Soonklang, Somying Promso, Chirayu Auewarakul, and Chintana Tocharoentanaphol. "Association of MTHFR Polymorphisms and Chromosomal Abnormalities in Leukemia." Disease Markers 32, no. 2 (2012): 115–21. http://dx.doi.org/10.1155/2012/292507.
Full textAbstract:
Genetic variation in MTHFR gene might explain the interindividual differences in the reduction of DNA repaired and the increase of chromosome breakage and damage. Nowadays, chromosomal rearrangement is recognized as a major cause of lymphoid malignancies. In addition, the association of MTHFR polymorphisms with aneuploidy was found in several studies, making the MTHFR gene as a good candidate for leukemia etiology. Therefore, in this study, we investigated the common sequence variation, 677C>T and 1298A>C in the MTHFR gene of 350 fixed cell specimens archived after chromosome analysis. The distribution of the MTHFR polymorphisms frequency was compared in leukemic patients with structural chromosome abnormality and chromosome aneuploidy, as well as in those with no evidence of chromosome abnormalities. We observed a significant decrease in the distribution of T allele in 677C>T polymorphisms among patients with chromosomal abnormalities including both structural aberration and aneuploidy. The same significance result also found in patients with structural aberration when compare with the normal karyotype patients. Suggesting that polymorphism in the MTHFR gene was involved in chromosome abnormalities of leukemia. However, further investigation on the correlation with the specific types of chromosomal aberrations is needed.
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Ocalewicz, K., and S. Dobosz. "Karyotype variation in the albino rainbow trout (Oncorhynchus mykiss (Walbaum))." Genome 52, no. 4 (April 2009): 347–52. http://dx.doi.org/10.1139/g09-009.
Full textAbstract:
A Robertsonian polymorphism resulting in diploid chromosome number ranging from 59 to 61 and constant chromosome arm number (fundamental number = 104) was observed in the albino rainbow trout ( Oncorhynchus mykiss (Walbaum)) from the yellow color strain. In one individual, 90 mitotic chromosomes and 156 chromosome arms were counted, indicating the fish as a triploid. Morphology of the chromosomes, DAPI staining, and the cytogenetic location of 5S rDNA sequences showed sex-related chromosomal heteromorphism in the specimens. Additionally, length polymorphism of the X chromosome was detected in the studied individuals and two morphs of the X chromosome were described, XL and XS, according to the size of its short arm (p). The XS was observed in the female as well as male albino rainbow trout; however, among females, no XSXS genotype was found. After primed in situ labeling with 5S rDNA primers, the p-arms of both types of the X chromosome showed similar hybridization signals. On the other hand, fluorescence in situ hybridization with telomeric PNA (peptide nucleic acid) probe exhibited weak hybridization spots on the p-arm of the XS chromosome compared with the distinct hybridization spots observed on the XL p-arm. This could reflect a different telomere length on the p-arm of the XS and XL chromosomes. Partial translocation and deletion of the X chromosome p-arm are considered to be responsible for the p-arm length difference between the two morphological variants of X chromosome.
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Felip, Alicia, Atushi Fujiwara, William P. Young, Paul A. Wheeler, Marc Noakes, Ruth B. Phillips, and Gary H. Thorgaard. "Polymorphism and differentiation of rainbow trout Y chromosomes." Genome 47, no. 6 (December 1, 2004): 1105–13. http://dx.doi.org/10.1139/g04-059.
Full textAbstract:
Most fish species show little morphological differentiation in the sex chromosomes. We have coupled molecular and cytogenetic analyses to characterize the male-determining region of the rainbow trout (Oncorhynchus mykiss) Y chromosome. Four genetically diverse male clonal lines of this species were used for genetic and physical mapping of regions in the vicinity of the sex locus. Five markers were genetically mapped to the Y chromosome in these male lines, indicating that the sex locus was located on the same linkage group in each of the lines. We also confirmed the presence of a Y chromosome morphological polymorphism among these lines, with the Y chromosomes from two of the lines having the more common heteromorphic Y chromosome and two of the lines having Y chromosomes morphologically similar to the X chromosome. The fluorescence in situ hybridization (FISH) pattern of two probes linked to sex suggested that the sex locus is physically located on the long arm of the Y chromosome. Fishes appear to be an excellent group of organisms for studying sex chromosome evolution and differentiation in vertebrates because they show considerable variability in the mechanisms and (or) patterns involved in sex determination.Key words: sex chromosomes, sex markers, cytogenetics, rainbow trout, fish.
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Konerat, Jocicléia Thums, Vanessa Bueno, Lucas Baumgartner, Isabel Cristina Martins-Santos, and Vladimir Pavan Margarido. "B chromosome and NORs polymorphism in Callichthys callichthys (Linnaeus, 1758) (Siluriformes: Callichthyidae) from upper Paraná River, Brazil." Neotropical Ichthyology 12, no. 3 (June 23, 2014): 603–9. http://dx.doi.org/10.1590/1982-0224-20130189.
Full textAbstract:
B chromosomes are extra chromosomes from the normal chromosomal set, found in different organisms, highlighting their presence on the group of fishes. Callichthys callichthys from the upper Paraná River has a diploid number of 56 chromosomes (26 m-sm + 30 st-a) for both sexes, with the presence of a sporadically acrocentric B chromosome. Moreover, one individual presented a diploid number of 57 chromosomes, with the presence of a morphologically ill-defined acrocentric B chromosome in all analyzed cells. The physical mapping of 5S and 18S rDNA shows multiple 5S rDNA sites and only one pair of chromosomes with 18S sites in C. callichthys, except for two individuals. These two individuals presented a third chromosome bearing NORs (Ag-staining and 18S rDNA) where 5S and 18S rDNA genes are syntenic, differing only in position. The dispersion of the 18S rDNA genes from the main st-achromosome pair 25 to one of the chromosomes from the m-sm pair 4 would have originated two variant individuals, one of which with the ill-defined acrocentric B chromosome. Mechanisms to justify the suggested hypothesis about this B chromosome origin are discussed in the present study.
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Wu, Dandan, Namei Yang, Qian Xiang, Mingkun Zhu, Zhongyan Fang, Wen Zheng, Jiale Lu, et al. "Pseudorogneria libanotica Intraspecific Genetic Polymorphism Revealed by Fluorescence In Situ Hybridization with Newly Identified Tandem Repeats and Wheat Single-Copy Gene Probes." International Journal of Molecular Sciences 23, no. 23 (November 26, 2022): 14818. http://dx.doi.org/10.3390/ijms232314818.
Full textAbstract:
The genus Pseudoroegneria (Nevski) Löve (Triticeae, Poaceae) with its genome abbreviated ‘St’ accounts for more than 60% of perennial Triticeae species. The diploid species Psudoroegneria libanotica (2n = 14) contains the most ancient St genome. Therefore, investigating its chromosomes could provide some fundamental information required for subsequent studies of St genome evolution. Here, 24 wheat cDNA probes covering seven chromosome groups were mapped in P. libanotica to distinguish homoelogous chromosomes, and newly identified tandem repeats were performed to differentiate seven chromosome pairs. Using these probes, we investigated intraspecific population chromosomal polymorphism of P. libanotica. We found that (i) a duplicated fragment of the 5St long arm was inserted into the short arm of 2St; (ii) asymmetrical fluorescence in situ hybridization (FISH) hybridization signals among 2St, 5St, and 7St homologous chromosome pairs; and (iii) intraspecific population of polymorphism in P. libanotica. These observations established the integrated molecular karyotype of P. libanotica. Moreover, we suggested heterozygosity due to outcrossing habit and adaptation to the local climate of P. libanotica. Specifically, the generated STlib_96 and STlib_98 repeats showed no cross-hybridization signals with wheat chromosomes, suggesting that they are valuable for identifying alien chromosomes or introgressed fragments of wild relatives in wheat.
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Li, J., D. L. Klindworth, F. Shireen, X. Cai, J. Hu, and S. S. Xu. "Molecular characterization and chromosome-specific TRAP-marker development for Langdon durum D-genome disomic substitution lines." Genome 49, no. 12 (December 2006): 1545–54. http://dx.doi.org/10.1139/g06-114.
Full textAbstract:
The aneuploid stocks of durum wheat ( Triticum turgidum L. subsp. durum (Desf.) Husnot) and common wheat ( T. aestivum L.) have been developed mainly in ‘Langdon’ (LDN) and ‘Chinese Spring’ (CS) cultivars, respectively. The LDN-CS D-genome chromosome disomic substitution (LDN-DS) lines, where a pair of CS D-genome chromosomes substitute for a corresponding homoeologous A- or B-genome chromosome pair of LDN, have been widely used to determine the chromosomal locations of genes in tetraploid wheat. The LDN-DS lines were originally developed by crossing CS nulli-tetrasomics with LDN, followed by 6 backcrosses with LDN. They have subsequently been improved with 5 additional backcrosses with LDN. The objectives of this study were to characterize a set of the 14 most recent LDN-DS lines and to develop chromosome-specific markers, using the newly developed TRAP (target region amplification polymorphism)-marker technique. A total of 307 polymorphic DNA fragments were amplified from LDN and CS, and 302 of them were assigned to individual chromosomes. Most of the markers (95.5%) were present on a single chromosome as chromosome-specific markers, but 4.5% of the markers mapped to 2 or more chromosomes. The number of markers per chromosome varied, from a low of 10 (chromosomes 1A and 6D) to a high of 24 (chromosome 3A). There was an average of 16.6, 16.6, and 15.9 markers per chromosome assigned to the A-, B-, and D-genome chromosomes, respectively, suggesting that TRAP markers were detected at a nearly equal frequency on the 3 genomes. A comparison of the source of the expressed sequence tags (ESTs), used to derive the fixed primers, with the chromosomal location of markers revealed that 15.5% of the TRAP markers were located on the same chromosomes as the ESTs used to generate the fixed primers. A fixed primer designed from an EST mapped on a chromosome or a homoeologous group amplified at least 1 fragment specific to that chromosome or group, suggesting that the fixed primers might generate markers from target regions. TRAP-marker analysis verified the retention of at least 13 pairs of A- or B-genome chromosomes from LDN and 1 pair of D-genome chromosomes from CS in each of the LDN-DS lines. The chromosome-specific markers developed in this study provide an identity for each of the chromosomes, and they will facilitate molecular and genetic characterization of the individual chromosomes, including genetic mapping and gene identification.
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Willhoeft, Ute, and Gerald Franz. "Comparison of the mitotic karyotypes of Ceratitis capitata, Ceratitis rosa, and Trirhithrum coffeae (Diptera: Tephritidae) by C-banding and FISH." Genome 39, no. 5 (October 1, 1996): 884–89. http://dx.doi.org/10.1139/g96-111.
Full textAbstract:
The sex chromosomes of the tephritid fruit fly Ceratitis capitata (Wiedemann) are heteromorphic. The male-determining region was located on the Y chromosome by deletion mapping using unbalanced offspring from several translocation strains. In addition, we showed that only 15% of the Y chromosome is required for male determination and male fertility. Based on this result, we expected to find Y-chromosomal length polymorphism in natural populations. Using fluorescence in situ hybridization with two repetitive DNA probes that label the Y chromosome, no obvious size differences were detected in seven wild-type strains and three mutant strains. As the medfly is probably of East African origin, we also analyzed two wild-type strains established recently from pupae sampled in Kenya. The Y chromosomes show a polymorphism in the hybridization pattern of a repetitive Y-specific medfly clone. However, the overall size of the Y chromosome is similar to that of the other strains. Besides C. capitata, the tephritid fruit flies Ceratitis (Pterandrus) rosa Karsch and Trirhithrum coffeae Bezzi also emerged from pupae sampled in Kenya. Their karyotype was analyzed by C-banding. Furthermore, the ribosomal genes were mapped to the sex chromosomes in these two species. Key words : Ceratitis capitata, Tephritidae, C-Banding, FISH, rDNA.
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Brockhouse, C., J. A. B. Bass, and N. A. Straus. "Chromocentre polymorphism in polytene chromosomes of Simulium costatum (Diptera: Simuliidae)." Genome 32, no. 4 (August 1, 1989): 510–15. http://dx.doi.org/10.1139/g89-476.
Full textAbstract:
The polytene chromosomes of the black fly species Simulium (Nevermannia) costatum are joined at the centromeres in a strongly heterochromatic chromocentre. Examination of the larval salivary gland chromosomes revealed two populations with a unique polymorphism for attachment to the chromocentre involving all centromeres. All three homologous pairs of chromosomes are polymorphic for centromeres that do not join to the chromocentre. Samples from one of these populations were large enough for thorough study. In this population, the attachment polymorphism is in Hardy-Weinberg equilibrium for two of the centromeres and was in the same frequency for 2 successive years of sampling. The polymorphism could be either primary, retained from an ancestral nonchromocentric state, or secondary, evolving independently or introduced via hybrid introgression. The evolution of chromocentres is discussed in the context of species in the Simulium vernum group.Key words: black fly, polytene chromosome, chromocentre, polymorphism, evolution.
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Asamizu, Erika, Kenta Shirasawa, Hideki Hirakawa, Shusei Sato, Satoshi Tabata, Kentaro Yano, Tohru Ariizumi, Daisuke Shibata, and 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 (November 27, 2012): 1–8. http://dx.doi.org/10.1155/2012/437026.
Full textAbstract:
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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Eenennaam, A. L., J. D. Murray, and J. F. Medrano. "Mitotic analysis of the North American white sturgeon, Acipenser transmontanus Richardson (Pisces, Acipenseridae), a fish with a very high chromosome number." Genome 41, no. 2 (April 1, 1998): 266–71. http://dx.doi.org/10.1139/g98-018.
Full textAbstract:
The average chromosome number of the North American white sturgeon, Acipenser transmontanus Richardson, was found to be 271 ± 2.5 (ranging from 265 to 276). This number is significantly higher than previous estimates for this species. A representative karyotype was found to consist of 132 meta- and submeta-centric chromosomes, 44 acrocentric chromosomes, and 98 microchromosomes. An improved C-banding technique revealed variation (2-7) between animals in the number of entirely heterochromatic metacentric chromosomes. These heterochromatic chromosomes may represent supernumerary chromosomes. There was no cytogenetic evidence of a heteromorphic sex chromosome pair or any sex-related chromosomal polymorphism in either sex of this species.Key words: C-banding, fish, karyotype, supernumerary chromosomes, white sturgeon.
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Ehlers, Anke, Stephan Beck, Simon A. Forbes, John Trowsdale, Armin Volz, Ruth Younger, and Andreas Ziegler. "MHC-Linked Olfactory Receptor Loci Exhibit Polymorphism and Contribute to Extended HLA/OR-Haplotypes." Genome Research 10, no. 12 (December 1, 2000): 1968–78. http://dx.doi.org/10.1101/gr.120400.
Full textAbstract:
Clusters of olfactory receptor (OR) genes are found on most human chromosomes. They are one of the largest mammalian multigene families. Here, we report a systematic study of polymorphism of OR genes belonging to the largest fully sequenced OR cluster. The cluster contains 36 OR genes, of which two belong to the vomeronasal 1 (V1-OR) family. The cluster is divided into a major and a minor region at the telomeric end of the HLA complex on chromosome 6. These OR genes could be involved in MHC-related mate preferences. The polymorphism screen was carried out with 13 genes from the HLA-linked OR cluster and three genes from chromosomes 7, 17, and 19 as controls. Ten human cell lines, representing 18 different chromosome 6s, were analyzed. They were from various ethnic origins and exhibited different HLA haplotypes. All OR genes tested, including those not linked to the HLA complex, were polymorphic. These polymorphisms were dispersed along the coding region and resulted in up to seven alleles for a given OR gene. Three polymorphisms resulted either in stop codons (genes hs6M1-4P,hs6M1-17) or in a 16–bp deletion (gene hs6M1-19P), possibly leading to lack of ligand recognition by the respective receptors in the cell line donors. In total, 13 HLA-linked OR haplotypes could be defined. Therefore, allelic variation appears to be a general feature of human OR genes.[The sequence data reported in this paper have been submitted to EMBL under accession nos. AC006137, AC004178, AJ132194, AL022727, AL031983,AL035402, AL035542, Z98744, CAB55431, AL050339, AL035402, AL096770,AL133267, AL121944, Z98745, AL021808, and AL021807.]
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Gale, M. D., P. J. Sharp, S. Chao, and C. N. Law. "Applications of genetic markers in cytogenetic manipulation of the wheat genomes." Genome 31, no. 1 (January 1, 1989): 137–42. http://dx.doi.org/10.1139/g89-025.
Full textAbstract:
A molecular map of wheat, Triticum aestivum, is being developed. Problems associated with the large genome size, the large number of linkage groups, polyploidy, and limited polymorphism at the DNA level are being overcome. In addition to the breeding applications expected from the map, various uses for restriction fragment length polymorphism markers as tools in cytogenetic manipulation of wheat chromosomes and those from related species are being found. These include identification of aneuploid genotypes, added precision in intervarietal chromosome manipulations, tests of chromosome stability, identification of alien chromosomes, and marker-aided introgression of genes of agronomic importance from related species.Key words: wheat, restriction fragment length polymorphism, genetic maps, aneuploidy, alien chromosomes.
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Vorsanova, S. G., I. V. Solovyev, O. S. Kurinnaya, V. S. Kravets, A. D. Kolotii, I. A. Demidova, V. O. Sharonin, Yu B. Yurov, and I. Yu Yurov. "The Y chromosome disomy syndrome (47, XYY) in children with mental retardation, deviations of sex development and different genome anomalies: molecular cytogenetic studies." Rossiyskiy Vestnik Perinatologii i Pediatrii (Russian Bulletin of Perinatology and Pediatrics) 65, no. 2 (May 15, 2020): 40–48. http://dx.doi.org/10.21508/1027-4065-2020-65-2-40-48.
Full textAbstract:
The article present the results of retrospectively analyzed children (4424 boys) with mental and psychomotor retardation, congenital malformations and/or developmental micro anomalies. 23 children had various forms of Y chromosome dysomy syndrome. The frequency of this syndrome in the studied cohort was 0.52%; and in this connection the authors discussed the role of Y-chromosome in the origin of mental retardation. Besides, the chromosome instability in sex and somatic cells is supposed to be a common mechanism of different chromosomal anomalies. The authors discussed the possibility of cytogenetic and molecular cytogenetic diagnosis, and also clinical polymorphism of the syndrome. The authors established the necessity of molecular cytogenetic technologies in the diagnosis of different forms of the syndrome, including mosaic forms and isodicentric chromosomes-connected forms. The severity of clinical symptoms doesn’t depend on presence of regular or mosaic forms of the syndrome. The study assumes a possible connection of clinical polymorphism with mosaisism, associated with the presence of abnormal cells (cell lines) in different tissues, together with the role of Y chromosome in the origin of mental retardation in children with Y- chromosome disomy syndrome and other chromosomal anomalies. The authors underline the necessity of molecular cytogenetic diagnosis of different forms of the syndrome for correct medical and genetic consultation.
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Maffei, E. M. D., M. A. Marin-Morales, P. M. Ruas, and C. F. Ruas. "Numerical chromosome polymorphism in Mikania cordifolia Willd. (Asteraceae)." Genetics and Molecular Biology 22, no. 4 (December 1999): 609–12. http://dx.doi.org/10.1590/s1415-47571999000400023.
Full textAbstract:
Cytogenetical analysis of Mikania cordifolia, from southeastern Brazil, using the conventional Feulgen method, showed a chromosome number of 2n = 36. Previous karyotypic descriptions for this species showed a numerical chromosome variation of 2n = 34 to 38. There was a secondary constriction in every metaphase in the first chromosome pair, which constitutes a cytological marker. Small extranumerary chromosomes with numerical variation in the same plant were found in the tenth chromosome pair.
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Harshini, Vemula, P. Kumarasamy, and S. M. K. Karthickeyan. "A rare chromosomal polymorphism in a Kangayam bull (Bos indicus) of south India." Comparative Cytogenetics 15, no. 4 (December 15, 2021): 459–65. http://dx.doi.org/10.3897/compcytogen.v15.i4.71295.
Full textAbstract:
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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Kokotas, Haris, Maria Grigoriadou, Margareta Mikkelsen, Aglaia Giannoulia-Karantana, and Michael B. Petersen. "Investigating the Impact of the Down Syndrome Related Common MTHFR 677C>T Polymorphism in the Danish Population." Disease Markers 27, no. 6 (2009): 279–85. http://dx.doi.org/10.1155/2009/725614.
Full textAbstract:
Chromosomal aneuploidy consists the leading cause of fetal death in our species. Around 50% of spontaneous abortions until 15 weeks of gestational age are chromosomally aneuploid, with trisomies accounting for 50% of the abnormal abortions. Trisomy 21 is the most common chromosome abnormality in liveborns and is usually the result of nondisjunction of chromosome 21 in meiosis in either oogenesis or spermatogenesis. To investigate the relationship between folate metabolism and Down syndrome (DS) in a Danish population, we analyzed the common 677C>T genetic polymorphism in the methylenetetrahydrofolate reductase (MTHFR) gene. Our cohort consisted of 181 mothers of children with DS versus 1,084 healthy controls. Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) were used to examine theMTHFR677C>T polymorphism. No significant association between the polymorphism and the risk for DS was found. We conclude that the commonMTHFR677C>T polymorphism is not likely to be a maternal risk factor for DS in our cohort and that the difference to previous studies can probably be explained by small sample size or geographic variation in gene polymorphisms involving gene-nutritional or gene-gene or gene-nutritional-environmental factors.
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Buño, I., J. L. Fernández, C. López-Fernández, J. L. Díez-Martín, and 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, no. 1 (February 1, 2001): 120–27. http://dx.doi.org/10.1139/g00-088.
Full textAbstract:
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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Sangines, N., and M. Aguilera. "Chromosome polymorphism in Holochilus venezuelae (Rodentia: Cricetidae): C- and G-bands." Genome 34, no. 1 (February 1, 1991): 13–18. http://dx.doi.org/10.1139/g91-003.
Full textAbstract:
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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Ramírez, Corália CL, and Eliana MB Dessen. "Chromosomal evidence for sibling species of the malaria vector Anopheles cruzii." Genome 43, no. 1 (February 1, 2000): 143–51. http://dx.doi.org/10.1139/g99-103.
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An analysis of the ovarian polytene chromosomes of Anopheles cruzii from three localities in Southeast Brazil revealed the existence of two genetic entities within this morphologically uniform taxon. These cryptic species differed in the banding patterns of the X chromosome and 3L arm. A pattern of bands that cannot be explained by the fixation of any of the known inversions in chromosome X was revealed and named chromosomal form B to distinguish it from the standard pattern of this X chromosome, form A. Each chromosomal form is characterized by a different set of inversions. The lack of heterozygotes (A/B) for these X chromosome forms in populations where both forms coexist is evidence of absence or limited gene flow between the two groups. Key words: Anopheles cruzii, inversion polymorphism, sibling species.
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Lemskaya, Natalya A., Irina V. Kartavtseva, Nadezhda V. Rubtsova, Fedor N. Golenishchev, Irina N. Sheremetyeva, and Alexander S. Graphodatsky. "Chromosome Polymorphism in Microtus(Alexandromys)mujanensis (Arvicolinae, Rodentia)." Cytogenetic and Genome Research 146, no. 3 (2015): 238–42. http://dx.doi.org/10.1159/000439096.
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The Muya Valley vole (Microtus mujanensis) has a constant diploid chromosome number of 2n = 38, but an unstable karyotype with polymorphic chromosome pairs. Here, we describe 4 karyotypic variants involving 2 polymorphic chromosome pairs, MMUJ8 and MMUJ14, in 6 animals from Buryatia using a combination of GTG-banding and chromosome painting with M. agrestis probes. We suggest that the polymorphic pairs MMUJ8 and MMUJ14 were formed through pericentric inversions that played a major role during karyotype evolution of the species. We also propose that the stable diploid number with some ongoing polymorphism in the number of chromosome arms indicates that this evolutionarily young endemic species of Russian Far East is on the way to karyotype and likely species stabilization.
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Habde, Sonali, S. K. Singh, Korada Mounika, Amrutlal Khaire, D. K. Singh, and Prasanta Kumar Majhi. "STUDY OF ALLELIC VARIATION AT GENOME WIDE SSR LOCI IN PARENTS OF MAPPING POPULATION FOR HIGH GRAIN ZINC IN RICE (Oryza sativa L.)." Journal of Experimental Biology and Agricultural Sciences 8, no. 5 (October 25, 2020): 558–75. http://dx.doi.org/10.18006/2020.8(5).558.575.
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Rice (Oryza sativa L.) is the source of energy and nutrition for more than half of the world’s population hence it is a crop of global significance. Breeding of mineral dense rice varieties is the main target of biofortification strategy to address micronutrient malnutrition globally. Landraces and local genotypes are proven sources of novel alleles and are a promising donor for high grain mineral. A parental polymorphism survey is a prerequisite of any QTL mapping experiment. Present study consisting of SSR markers based parental polymorphism survey at IRRI South Asia Hub ICRISAT, Hyderabad. Parents of mapping population viz Rajendrakasturi (short grain aromatic rice variety with low grain zinc content) and URG-30 (a local genotype from Eastern Uttar Pradesh with high grain zinc content) were screened with 1013 microsatellite markers covering the entire length of all 12 chromosomes to study allelic variation at genome-wide SSR loci. The geographical diverse origin of parents is reflected in genotypic variations in terms of polymorphism. Out of 1013 whole genome wide SSR markers screened, 294 were found to be polymorphic which resulted in 29.02% polymorphism between the two parents. The highest polymorphism was observed with chromosome 4 (40.96%) whereas the lowest polymorphism was observed in chromosome 9 (16%). Based on the outcomes of the present study, a set of genome-wide polymorphic SSRs will be selected for genotyping of mapping population, preparation of linkage map and QTL analysis for high grain zinc content, iron content, grain quality and yield traits.
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Bhargava, Kadthala, M. Sreedhar, S. Vanisri, Ramya Rathod, V. Jhansi Lakshmi, and K. Parimala. "Parental Polymorphism Survey for Identifying Genes/QTLs for BPH Resistance in Assam Land Race 10-3." International Journal of Bio-resource and Stress Management 14, Jun, 6 (June 27, 2023): 924–34. http://dx.doi.org/10.23910/1.2023.3498.
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The current research was taken up at Institute of Biotechnology (IBT), PJTSAU, Hyderabad Telangana, India in kharif from August to November, 2021 to access the parental polymorphism between 10-3 and Telangana Sona. 10-3, an Assam landrace, is a bold grain rice variety with high BPH resistance to biotype-4. Whereas, Telangana Sona (RNR 15048) is a short and slender grain variety of rice that is popular among farmers and consumers across Telangana and other Indian states due to its high yield and low glycemic index. Despite being blast resistant, Telangana Sona is susceptible to the insect pest Brown Plant hopper (BPH) Nilaparvata lugens (Stål). The present study aimed to characterize the parental polymorphism between 10–3 and Telangana sona to facilitate mapping of genetic loci linked with BPH resistance in the 10–3 and to optimize the retention of favourable alleles from Telangana sona during marker assisted backcross breeding. Eight hundred and sixteen highly variable Simple Sequence Repeats (SSRs) including thirty-five BPH linked markers covering 12 chromosomes were used to assess DNA polymorphism between 10-3 and Telangana Sona. Out of 816 markers screened, 97 (11.89%) were found to be polymorphic between 10–3 and Telangana Sona of which, 82 were genomic SSRs and 15 were BPH linked markers. Chromosome 6 exhibited highest polymorphism percentage with a value of 30%, indicating that this chromosome is useful in studying parental variation and lowest polymorphism percentage found on chromosome 5 (3.49%). These 97 polymorphic markers will help in construction of linkage map for identifying QTLs linked with BPH resistance and for marker assisted backcrossing breeding in Telangana Sona.
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Montchamp-Moreau, Catherine, and Michel Cazemajor. "Sex-Ratio Drive in Drosophila simulans: Variation in Segregation Ratio of X Chromosomes From a Natural Population." Genetics 162, no. 3 (November 1, 2002): 1221–31. http://dx.doi.org/10.1093/genetics/162.3.1221.
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Abstract The sex-ratio trait that exists in a dozen Drosophila species is a case of naturally occurring X chromosome drive that causes males to produce female-biased progeny. Autosomal and Y polymorphism for suppressors are known to cause variation in drive expression, but the X chromosome polymorphism has never been thoroughly investigated. We characterized 41 X chromosomes from a natural population of Drosophila simulans that had been transferred to a suppressor-free genetic background. We found two clear-cut groups of chromosomes, sex-ratio and standard. The sex-ratio X chromosomes differed in their segregation ratio (81-96% females in the progeny), the less powerful drivers being less stable in their expression. A sib analysis, using a moderate driver, indicated that within-X variation in drive expression depended on genetic (autosomal) or epigenetic factors and that the age of the males also affected the trait. The other X chromosomes produced equal or roughly equal sex ratios, but again with significant variation. The continuous pattern of variation observed within both groups suggested that, in addition to a major sex-ratio gene, many X-linked loci of small effect modify the segregation ratio of this chromosome and are maintained in a polymorphic state. This was also supported by the frequency distribution of sex ratios produced by recombinant X chromosomes.
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Bernard, Lynn E., and Stephen Wood. "Human chromosome 5 sequence primer amplifies Alu polymorphisms on chromosomes 2 and 17." Genome 36, no. 2 (April 1, 1993): 302–9. http://dx.doi.org/10.1139/g93-042.
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Members of the Alu family of repetitive elements occur frequently in the human genome and are often polymorphic. Techniques involving Alu element mediated polymerase chain reactions (Alu PCR) allow the isolation of region-specific human DNA fragments from mixed DNA sources. Such fragments are a source of region-specific Alu elements useful for the detection of Alu-related polymorphisms. A clone from human chromosome 5, corresponding to locus D5F40S1, was isolated using Alu PCR differential hybridization. Alu elements within this clone were investigated for the presence of potentially polymorphic 3′ polyA tails. Primers were devised to amplify the 3′ polyA tail of an Alu element present within the clone. One primer, D5F40S1-T, was specific to the DNA flanking the 3′ end of the Alu element, and the other primer was homologous to sequences within the element. When these primers were used in PCR reactions, products from chromosomes 2 and 17 (loci D2F40S2 and D17F40S3) were amplified in addition to the expected product from chromosome 5. The most likely explanation for this nonspecific amplification is that the D5F40S1-T primer is located within a low-copy repetitive element that is 3′ of the Alu element. This phenomenon presents a potential problem for the identification of region-specific Alu polymorphisms.Key words: Alu polymorphism, human chromosome 5, polymerase chain reaction, D5F40S1, D2F40S2, D17F40S3.
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Yi, Soojin, Doris Bachtrog, and Brian Charlesworth. "A Survey of Chromosomal and Nucleotide Sequence Variation inDrosophila miranda." Genetics 164, no. 4 (August 1, 2003): 1369–81. http://dx.doi.org/10.1093/genetics/164.4.1369.
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AbstractThere have recently been several studies of the evolution of Y chromosome degeneration and dosage compensation using the neo-sex chromosomes of Drosophila miranda as a model system. To understand these evolutionary processes more fully, it is necessary to document the general pattern of genetic variation in this species. Here we report a survey of chromosomal variation, as well as polymorphism and divergence data, for 12 nuclear genes of D. miranda. These genes exhibit varying levels of DNA sequence polymorphism. Compared to its well-studied sibling species D. pseudoobscura, D. miranda has much less nucleotide sequence variation, and the effective population size of this species is inferred to be several-fold lower. Nevertheless, it harbors a few inversion polymorphisms, one of which involves the neo-X chromosome. There is no convincing evidence for a recent population expansion in D. miranda, in contrast to D. pseudoobscura. The pattern of population subdivision previously observed for the X-linked gene period is not seen for the other loci, suggesting that there is no general population subdivision in D. miranda. However, data on an additional region of period confirm population subdivision for this gene, suggesting that local selection is operating at or near period to promote differentiation between populations.
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Woznicki, Pawel, Malgorzata Jankun, and Miroslaw Luczynski. "Chromosome polymorphism in." Aquatic Sciences 60, no. 4 (1998): 367. http://dx.doi.org/10.1007/s000270050047.
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Vahidi, Parisa, Seyed Ali Rahmani, and Nahid Hadige Rezvan. "Study of pregnant women with high risk of fetus abnormalities by routine cytogenetics method (karyotyping) and molecular method (FISH) by using X and Y probs and comparing the advantages and disadvantages of these methods in the northwest of Iran's patients." Medical Journal of Tabriz University of Medical Sciences and Health Services 43, no. 1 (April 17, 2021): 108–15. http://dx.doi.org/10.34172/mj.2021.035.
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Background: The health of the fetus during the 9 months of pregnancy is very important for every pregnant couple. Identifying carriers of the genetic diseases and their diagnosis before birth, controls the disease's prevalence and does not impose huge costs on the patient's family and community. This study aimed to evaluate the rapid prenatal diagnosis importance in the chromosomal abnormalities identification. Methods: 50 amniotic fluid samples were studied by karyotyping and fluorescence in situ hybridization (FISH). Karyotyping was performed on me taphase chromosomes to identify all the chromosomal abnormalities and FISH detected chromosomal abnormalities by using X and Y probs, as the rapid method. Results: We identified one cases of Down syndrome (2%), three cases of extension in the polymorphism region of P arms of chromosome 15(15p+) (6%), one cases of extension in the polymorphism region of chromosome 9 (9 qh+) (2%), one case of peristaltic inversion in chromosome Y (2%), one case of XYY mosaic embryo, 46, XY /47, XYY variant (2%) and one case with the extra unknown segment on P arms of chromosome 15 (2%). Conclusion: FISH is a useful method with high sensitivity to provide rapid results for couples who don't have enough time to end their pregnancy legally. In cases of X-linked diseases, it is a reliable method to learn the sex of the fetus. FISH is not able to detect structural anomalies, therefore karyotyping is required for absolute right outcomes of chromosome abnormalities.
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Nagano, Yasuhiko, Do Ha Kim, Li Zhang, Jill A. White, James C. Yao, Stanley R. Hamilton, and Asif Rashid. "Allelic alterations in pancreatic endocrine tumors identified by genome-wide single nucleotide polymorphism analysis." Endocrine-Related Cancer 14, no. 2 (June 2007): 483–92. http://dx.doi.org/10.1677/erc-06-0090.
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Pancreatic endocrine tumors (PETs) are uncommon and the genetic alterations in these indolent tumors are not well characterized. Chromosomal imbalances are frequent in tumors but PETs have not been studied by high-density single nucleotide polymorphism (SNP) array. We used genome-wide high-density SNP array analysis to detect copy number alterations using matched tumor and non-neoplastic tissue samples from 15 patients with PETs. In our study, whole or partial loss of chromosomes 1, 3, 11, 22 was present in 40, 47, 53, 40% of tumors respectively, and gain of chromosomes 5, 7, 12, 14, 17, and 20 was present in 47, 60, 47, 53, 53, and 47% of tumors respectively. One tumor had loss of heterozygosity of chromosome 3 and another of chromosome 22 without copy number alterations, suggesting uniparental disomy due to non-disjunction and deletion or to chromosomal recombination. Chromosomal aberrations of the autosomal chromosomes were correlated with chromosomal loss or gain of other chromosomes (r>0.5, P<0.5). About 60% of PETs had high allelic imbalances (AI) defined by more than four chromosomal aberrations, and 40% of tumors had low AI. The PETs with high AI were larger: the mean tumor size with high AI was 5.4 ± 3.1 cm compared with 2.3 ± 1.3 cm for low AI (P = 0.03). Our study shows that genome-wide allelotyping is a powerful new tool for the analysis of AI in PETs.
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Federico, Concetta, Desiree Brancato, Francesca Bruno, Daiana Galvano, Mariella Caruso, and Salvatore Saccone. "Robertsonian Translocation between Human Chromosomes 21 and 22, Inherited across Three Generations, without Any Phenotypic Effect." Genes 15, no. 6 (June 1, 2024): 722. http://dx.doi.org/10.3390/genes15060722.
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Chromosomal translocations can result in phenotypic effects of varying severity, depending on the position of the breakpoints and the rearrangement of genes within the interphase nucleus of the translocated chromosome regions. Balanced translocations are often asymptomatic phenotypically and are typically detected due to a decrease in fertility resulting from issues during meiosis. Robertsonian translocations are among the most common chromosomal abnormalities, often asymptomatic, and can persist in the population as a normal polymorphism. We serendipitously discovered a Robertsonian translocation between chromosome 21 and chromosome 22, which is inherited across three generations without any phenotypic effect, notably only in females. In situ hybridization with alpha-satellite DNAs revealed the presence of both centromeric sequences in the translocated chromosome. The reciprocal translocation resulted in a partial deletion of the short arm of both chromosomes 21, and 22, with the ribosomal RNA genes remaining present in the middle part of the new metacentric chromosome. The rearrangement did not cause alterations to the long arm. The spread of an asymptomatic heterozygous chromosomal polymorphism in a population can lead to mating between heterozygous individuals, potentially resulting in offspring with a homozygous chromosomal configuration for the anomaly they carry. This new karyotype may not produce phenotypic effects in the individual who presents it. The frequency of karyotypes with chromosomal rearrangements in asymptomatic heterozygous form in human populations is likely underestimated, and molecular karyotype by array Comparative Genomic Hybridization (array-CGH) analysis does not allow for the identification of this type of chromosomal anomaly, making classical cytogenetic analysis the preferred method for obtaining clear results on a karyotype carrying a balanced rearrangement.