Showing papers on "X chromosome published in 1971"
TL;DR: The mode of dose compensation for X chromosomes in kangaroos seems to be inactivation of the paternal X, in contrast to the random X inactivation characteristic of eutherian mammals.
Abstract: The mode of dose compensation for X chromosomes in kangaroos seems to be inactivation of the paternal X, in contrast to the random X inactivation characteristic of eutherian mammals.
227 citations
TL;DR: Random inactivation of one or other of the X chromosomes in female eutherians could have evolved from an ancestral paternal X inactivation, which has been retained in marsupials.
Abstract: Random inactivation of one or other of the X chromosomes in female eutherians could have evolved from an ancestral paternal X inactivation, which has been retained in marsupials.
140 citations
TL;DR: On the basis of staining reaction, late replicating heterochromatic regions fall into five categories, the relationships and functional significance of these categories is discussed.
Abstract: Cultured human peripheral blood lymphocytes were labelled with 3H-thymidine in the early or late S phase prior to mitosis. Quinacrine fluorescence patterns in metaphase chromosomes were then recorded photographically and the slides reprocessed for autoradiography so that the same metaphase cells were examined with the two techniques. The intensity and distribution of 3H-thymidine labelling was compared with the intensity and distribution of Q fluorescence with particular reference to chromosomes 1, 13, 14, 15, 17, 18, 19, 20, 21 and 22. It was found that chromosome regions showing bright fluorescence were also late replicating and that, in general, patterns of late replications reflected the patterns of fluorescence. Exceptions to this generalisation included the late labelling X chromosome in cells of female origin and areas near the centromeres on chromosomes 1, 9, 16 and 22. These centromeric regions show a dull fluorescence but, with exception of chromosome 9, are strongly Giemsa-positive in the ASG staining technique. On the basis of staining reaction, late replicating heterochromatic regions fall into five categories, the relationships and functional significance of these categories is discussed.
130 citations
TL;DR: In the normal XX female, one of the two X chromosomes is inactivated at an early stage in development.
Abstract: In the normal XX female, one of the two X chromosomes is inactivated at an early stage in development. This article discusses the current theories proposed to account for X inactivation.
112 citations
TL;DR: A karyotype of the mitotic chromosomes of the house mouse has been prepared based upon quinacrine fluorescence patterns and the tentative assignments of autosomal linkage groups (LG) to chromosomes as follows.
Abstract: A karyotype of the mitotic chromosomes of the house mouse has been prepared based upon quinacrine fluorescence patterns. All 19 pairs of autosomes and the X and Y chromosomes have been identified. Examination of the chromosomes of the following translocation stocks, T(11;?)1Ald, T(3;?)6Ca, T(2;9)138Ca, T(2;12)163H, and T(9;13)190Ca, have led to the tentative assignments of autosomal linkage groups (LG) to chromosomes as follows: LGII to chromosome number 10 (or 13), LGIII to 12 or 15, LGIX to 16, LGXI to 6, LGXII to 19 and LGXIII to 1. By definition, LGXX is on the X chromosome.
83 citations
TL;DR: Meiotic investigations revealed that the X and ring Y chromosome remained unpaired at diakinesis, and maturation in a subfertile male was delayed by at least three years.
Abstract: An account is given of a subfertile male carrying a ring Y chromosome in his blood. Meiotic investigations revealed that the X and ring Y chromosome remained unpaired at diakinesis, and maturation arr
61 citations
TL;DR: Findings suggest that the structural loci for both guanine phosphoribosyltransferase and G6PD have separated quite frequently through chromosome breakage and that they must be rather far apart on the X chromosome.
Abstract: Six interspecific somatic hybrid cell lines were derived from a mouse line deficient in hypoxanthine: guanine phosphoribosyltransferase (HGPRT) and human diploid cells with normal enzyme activity. Human HGPRT was present in all six hybrids and the clones derived from them. However, in two of the six, and in some clones from another two, human glucose-6-phosphate dehydrogenase (G6PD) was absent. Since the structural loci for both these enzymes are X-linked in man, these findings suggest that these two loci have separated quite frequently through chromosome breakage and that they must be rather far apart on the X chromosome.
53 citations
TL;DR: It has recently become possible to locate the major portion of the Y chromosomes in interphase nuclei1, and this technique is used to demonstrate that the Y chromosome is spatially associated with the nucleolus.
Abstract: INDIVIDUAL human chromosomes cannot be seen during interphase, and little is known of their intra-nuclear position during most of the cell cycle. The principal exception to this has been the X chromosomes: when there is more than one, they condense during interphase to form the sex chromatin, which is often located on the nuclear membrane. It has recently become possible to locate the major portion of the Y chromosome in interphase nuclei1, and we have used this technique to demonstrate that the Y chromosome is spatially associated with the nucleolus.
47 citations
Journal Article•
TL;DR: The child described in this report also has a translocation that involves the X chromosome and also displays a variety of abnormalities that are due not to a loss or gain of genetic material, but apparently to genetic inactivation.
Abstract: There have been several reports of translocations in man that involve the X chromosome. Lie et al. [1] reported a young woman with a karyotype in which a chromosomal segment of undetermined origin had been translocated to the short arm of the late-replicating X chromosome (46,XX,p+). Various abnormalities displayed by the young woman were interpreted as due to the loss of a portion of the short arm of the X involved in the translocation. Mukerjee and Burdette [2] described a child with multiple congenital abnormalities associated with a ring 3 and a late-replicating translocated 3/X chromosome (46,XX,p+,3r). The abnormalities in this case were due apparently to the loss of genetic material during the formation of the ring and the translocation, and to the subsequent instability of the ring itself. Neuhauser and Back [3] described a child with multiple abnormalities who had a translocation that involved a C group autosome and the latereplicating X chromosome (45,XX,p+,C-). The portion of the C group autosome not translocated to the X was lost, and again the abnormalities were attributed to the loss of genetic material. German [4] reported a malformed infant with a translocation involving a chromosomal segment of undetermined origin and the long arm of the late-replicating X (46,XX,q+). Her abnormalities were thought to be the result of genetic duplication. The child described in this report also has a translocation that involves the X chromosome and also displays a variety of abnormalities. Unlike the previously mentioned patients, however, she displays abnormalities that are due not to a loss or gain of genetic material, but apparently to genetic inactivation.
39 citations
TL;DR: A denaturating and renaturating technique, applied to mouse chromosomes, makes visible characteristic banding patterns by which all elements of the karyotype can be individually distinguished.
Abstract: A denaturating and renaturating technique, applied to mouse chromosomes, makes visible characteristic banding patterns by which all elements of the karyotype can be individually distinguished. The Y chromosome as a whole appears darkly stained. The X chromosome comprises 6.33% of the homogametic haploid set. The banding pattern of the chromosomes is compared with that obtained by aid of the quinacrine dihydrochloride fluorescence technique. After its use a banding pattern results which is similar to, but less distinct than, that found after the renaturation procedure.
38 citations
TL;DR: It is suggested that most of the heterochromatin disclosed by the DNA d-r method is formed by repetitious DNA; and that the Y chromosome and perhaps some autosome regions in guinea pigs are formed by a type of heterochromeatin with properties different from those of the constitutive and facultative heterochROMatin.
Abstract: The chromosome complement and patterns of heterochromatin distribution (as demonstrated by the DNA d-r method) were studied from three different guinea pigs. Karyotype analyses showed that one of the females had a heteromorphic sex pair formed by a submetacentric X chromosome and a subterminal X chromosome originated by a shortening of the short arm (x-chromosome). The heterochromatin was mainly found in the pericentromeric areas of the autosomes and X chromosomes and in the short arm of pair 7. The Y chromosome exhibited a degree of heterochromatinization different from that of pericentromeric areas.—The analysis of the heterochromatin distribution in the X chromosomes showed that the smaller size of the heteromorphic x-chromosoine was probably due to a lack of heterochromatin in its short arm. Moreover, two out of the three animals studied had a heteromorphic pattern of heterochromatinization in the pair 21 characterized by heterochromatinization of the pericentromeric area in one chromosome and almost complete heterochromatinization of the other homologue.—It is suggested that most of the heterochromatin disclosed by the DNA d-r method is formed by repetitious DNA; and that the Y chromosome and perhaps some autosome regions in guinea pigs are formed by a type of heterochromatin with properties different from those of the constitutive and facultative heterochromatin (intermediate heterochromatin).
TL;DR: The use of this technique to detect Y chromosomes in the amniotic fluid cells, in conjunction with a search for sex chromatin bodies in these cells, might provide a rapid and accurate means of prenatal sex determination.
Abstract: A FLUORESCENT staining technique has been described1–3 for identification of the Y chromosome in cells from various sources. The use of this technique to detect Y chromosomes in the amniotic fluid cells, in conjunction with a search for sex chromatin bodies in these cells, might provide a rapid and accurate means of prenatal sex determination.
TL;DR: A small metacentric chromosome was found to replace her second X chromosome, half of which was strongly fluorescing after staining with Quinacrinedihydrochloride, and late replicating after labelling with tritiated thymidine.
Abstract: The case of a sexchromatin negative “girl” with multiple malformations is presented. A small metacentric chromosome was found to replace her second X chromosome, half of which was strongly fluorescing after staining with Quinacrinedihydrochloride, and late replicating after labelling with tritiated thymidine. The chromosome was interpreted as a translocation chromosome between the long arms of a Y and a partially trisomic autosome.
TL;DR: The purpose of this communication is to provide additional cytological evidence for the association of the X and Y chromosomes at their short arms.
Abstract: EVIDENCE for the association of the X and Y chromosomes during the first meiotic division in man has been documented1,2. Until the centromere positions of the meiotic chromosomes were located with certainty, no information about the arm relationship between the two sex chromosomes could be obtained. The identification of the positions of the centromere in human male meiotic chromosomes at the late diplotene stage has been reported3. This observation revealed that the short arm of the Y chromosome was in association with the short arm of the X chromosome. Partial support for this finding was presented by Pearson and Bobrow4, who interpreted fluorescent staining of the distal end of the long arm of the Y chromosome of the XY bivalent in man as evidence that the short arm of the Y chromosome was associated with the X chromosome. Because the centromere position of the X chromosome could not be demonstrated in their material, it was not possible to determine which arm of the X chromosome was associated with the short arm of the Y chromosome. The purpose of this communication is to provide additional cytological evidence for the association of the X and Y chromosomes at their short arms.
TL;DR: The behaviour of X-linked glucose-6-phosphate dehydrogenase locus in a mule and two hinnies provides support for Lyon's single active X hypothesis.
Abstract: The behaviour of X-linked glucose-6-phosphate dehydrogenase locus in a mule and two hinnies provides support for Lyon's single active X hypothesis.
TL;DR: With differential staining it has been possible to demonstrate that the constitutive heterochromatin of the sex chromosomes are involved in the nucleolar organisation in this species, thus containing the ribosomal RNA cistrons.
Abstract: Microtus agrestis is characterised by long sex chromosomes, most of which are constitutively heterochromatic, and thus supposedly, genetically inactive. A method to assess the template activity of the chromosomes is to study the distribution of chromatid aberrations produced by H3UdR, among and within the chromosomes. In such a study, in female Microtus agrestis cells in culture, it was found that, a large number of localised chromatid aberrations was induced in the constitutively heterochromatic regions of both X chromosomes. The frequency distribution and types of aberrations were found to be cell cycle dependent. With differential staining it has been possible to demonstrate that the constitutive heterochromatin of the sex chromosomes are involved in the nucleolar organisation in this species, thus containing the ribosomal RNA cistrons.
TL;DR: Two new methods of measuring unusually large sex chromosomes are presented in rodents, of which three have unusually large X chromosomes, and one lagomorph has been made.
Abstract: Chromosome studies of six rodents, of which three have unusually large X chromosomes, and one lagomorph have been made. Two new methods of measuring unusually large sex chromosomes are presented. Comp
TL;DR: The findings support the hypothesis that heterochromatin does not participate in meiotic exchange, independent of possible homologies between the chromosome segments.
Abstract: In premeiotic stages of the male, the entire Y chromosome and the heterochromatio 3/4 of the X chromosome remain heavily condensed. Pairing of the sex chromosomes does not occur during zygotene. The sex vesicle stage lasts from middle pachytene to the beginning of diplotene. At the more advanced diplotene stages, X and Y lie again separate; chiasma formation has not been observed. Thus, it seems improbable that any pairing occurs at all between X and Y during meiosis. The findings support the hypothesis that heterochromatin does not participate in meiotic exchange, independent of possible homologies between the chromosome segments.
TL;DR: In XX; mei-S51 females, nonhomologous pairing of the fourth chromosomes occurs exclusively with the X chromosomes, implying that the specificity of nonhomologueous pairing (perhaps the size recognition mechanism demonstrated by Grell) is not affected by mei -S51.
Abstract: mei-S51 is a meiotic mutant of Drosophila melanogaster having the following properties:
1.
mei-S51 consists of two recessive genes, located near the centromere regions of the second and third chromosomes, which are both required for the expression of the mutant phenotype. Salivary analysis reveals normal structures for both the second and third chromosomes.
2.
mei-S51 has no effect in males but in females it causes a uniform decrease in X chromosome exchange, second chromosome exchange between c and bw, and increased nondisjunction of all chromosomes. Both of these effects appear to result from a defect prior to both exchange and disjunction, rather than one being the cause of the other.
3.
Nondisjunction in mei-S51 females having a normal sex chromosome complement is the result of nonhomologous pairing as is the greatly increased nondisjunction found for XXY; mei-S51 females. This nondisjunction is not competitive with exchange; that is, exchange occurs as frequently between the X chromosomes of XXY females as those of XX females in spite of a greatly increased frequency of X chromosome nondisjunction in the former.
4.
There is a pronounced increase in the frequency of nondisjunction in both XX and XXY; mei-S51 females if the X chromosomes are heterozygous for the inversion, In(1)dl49, although heterozygosity for In(1)dl49 causes-only a slight increase in nondisjunction in mei-S51+ (normal) XX females.
5.
It appears unlikely that, in all instances of nonhomologous pairing, both chromosomes of each bivalent pair nonhomologously. Rather, in many instances one chromosome pairs with a nonhomolog and the other two elements are distributed at random and without loss to the poles.
6.
In XX; mei-S51 females, nonhomologous pairing of the fourth chromosomes occurs exclusively with the X chromosomes, implying that the specificity of nonhomologous pairing (perhaps the size recognition mechanism demonstrated by Grell) is not affected by mei-S51.
TL;DR: Metaphase chromosomes of mice carrying Cattanach's translocation, which is the deletion of material from a medium-sized autosome and its insertion into an X chromosome, were stained with quinacrine mustard to identify the autosome involved in the translocation and localization of the transposed material within the X chromosome.
Abstract: Metaphase chromosomes of mice carrying Cattanach's translocation, which is the deletion of material from a medium-sized autosome and its insertion into an X chromosome, were stained with quinacrine mustard. Comparison of the fluorescence patterns of these chromosomes with those of the chromosomes of normal mice has allowed the identification of the autosome involved in the translocation and localization of the transposed material within the X chromosome. Since the material inserted into the X chromosome in Cattanach's translocation is known to carry part of linkage group I, we are now able to assign linkage group I to a specific chromosome pair of the normal fluorescent karyotype of the mouse.
TL;DR: The female mule, an interspecific hybrid of these two species, is an obligatory heterozygote for two electrophoretically distinguishable G6PD alleles that are known to be X-linked in the horse and donkey.
Abstract: THE glucose-6-phosphate dehydrogenase (G6PD) locus is known to be X-linked in the horse and donkey1,2. The female mule, an interspecific hybrid of these two species, is an obligatory heterozygote for two electrophoretically distinguishable G6PD alleles1,2.
TL;DR: A diagnosis of Turner's Syndrome is given to female patients who have small stature, primary amenorrhoea and a number of other variable stigmata.
Abstract: A diagnosis of Turner's Syndrome is given to female patients who have small stature, primary amenorrhoea and a number of other variable stigmata. The ovaries are absent and the genital ducts and external genitalia do not develop spontaneously beyond the pre-pubertal stage. Chromosome analysis shows that the majority have a 45, X karyotype, in which one of the pair of sex chromosomes is missing. Others have a structural abnormality of one of the two X chromosomes resulting in loss of short-arm material.
TL;DR: A male Chinese hamster cell line has been established through spontaneous transformation in a skin culture with selective advantage over other cell types in this cell line probably because they were more nearly genetically balanced.
Abstract: A male Chinese hamster cell line has been established through spontaneous transformation in a skin culture. Chromosome studies at passage 13 revealed one major and one minor type of pseudodiploid cells (77.3 and 20%). At passage 42, only the major subline persisted (78%). The two sublines, especially the major one, had selective advantage over other cell types in this cell line probably because they were more nearly genetically balanced. Autoradiographic studies indicated no overall increase in late replicating chromosomal elements in the two sublines. Both cell types lacked the X chromosome and chromosome 6, but they were largely compensated for by the presence of new marker chromosomes. However, more chromosomal material was missing in the minor type than in the major type, and this may account for the lower adaptability of the former.
TL;DR: Every sex chromosome constitution shows a specific nuclear pattern with regard to the number and size of drumsticks and F-bodies, which is of value in the screening of patients carrying sex chromosome abnormalities.
TL;DR: It is concluded that cells with deletions of heterochromatic segments of sex chromosomes, and, at least for some somatic cells, even the functional X portion, are viable and possess reproductive capability.
Journal Article•
01 Jan 1971
TL;DR: Since most chromosomes are difficult to classify, pairing is highly subjective, however, identification of the X chromosome offers no difficulty.
Abstract: Since most chromosomes are difficult to classify, pairing is highly subjective. However, identification of the X chromosome offers no difficulty.
TL;DR: It is shown that heterozygosity for bb deficiency is not the cause of this effect and a heterochromatic segment, associated with recombinational pairing in females, is postulated, and the genetic organization of the eu-heterochromatin junction is discussed.
Abstract: Recombinational behavior of the most proximal 34 complementation units of the Drosophila X-chromosome was studied. The studied region is divided into two equal-sized subsegments, the more proximal of which is thought to be part of the proximal heterochromatin. Recombination per complementation unit is homogenous along the 17 units of the distal segment with the rate being about twice that in the proximal segment. Deficiencies in the proximal segment have little effect on crossing-over in adjacent regions of the distal segment. If such deficiencies include the heterochromatin spanning the su(ƒ)-bb region, their efficiency in reducing crossing-over is sharply increased. It is shown that heterozygosity for bb deficiency is not the cause of this effect and a heterochromatic segment, associated with recombinational pairing in females, is postulated. In light of this preceding studies of the same region, the genetic organization of the eu-heterochromatin junction is discussed. To account for the relation between the number of complementation units and the number of salivary chromosome bands, as well as the types of mutations recovered, DNA content and sequence pattern, a supergenic functional unit named the “service unit” is postulated and its features are discussed.
TL;DR: It has been possible to identify the chromosomes in electron micrographs of a prophase neuroblast nucleus in Drosophila melanogaster by using stereophotographs of stacked transparencies made from serial sections using a stock carrying chromosomal rearrangements.
Abstract: It has been possible to identify the chromosomes in electron micrographs of a prophase neuroblast nucleus inDrosophila melanogaster by using stereophotographs of stacked transparencies made from serial sections. Depth was determined by increasing or decreasing the stereo angle. Identification was facilitated by the use of a stock carrying chromosomal rearrangements. In this stock only chromosome 2 is metacentric. Compound chromosomes [symbolized C(3L)RM and C(3R)RM] were formed from the left and from the right arms of chromosome 3, and the X chromosome was intercalated in an inverted position between the two arms of the Y (YSX·YL).—Three-dimensional aspects of the ultrastructure of these chromosomes were observed as follows. The compacted centric regions are composed of fibers coiled in irregular gyres. In the extended regions, the fibers subdivide and appear uncoiled except for regions of compaction—“chromomeres”—which are seen in both homologues. Each homologue appears to be composed of four fibers of 130 A diameter, a total of eight for the prophase chromosome. Since the larger neuroblast cells are 8C in the G2 phase, it would seem that the 130 A fiber is equivalent to the cytological chromatid.