bluuebunny/crossref_metadata_2025 huggingface dataset:
Variation in the number of genes for rRNA among human acrocentric chromosomes: correlation with frequency of satellite association
Authors: Warburton D. , Atwood K.C. , Henderson A.S.
Published: May 2008

Grain counts after hybridization of 125I-rRNA to human chromosomes indicate numerical polymorphism at the rDNA sites. Prephotographing procedures decrease labeling but do not change the proportions of labeled RNA annealed to different chromosomes. A positive correlation was found between the frequency of participation of a given chromosome in satellite associations and its rDNA content by the criterion of grain count. Certain individual chromosomes are clear exceptions to this correlation.
Quantitative analysis of human chromosome segregation in man-mouse somatic cell hybrids
Authors: Rushton A.R.
Published: May 2008

The presumed random and independent process of human chromosome segregation in man-mouse somatic cell hybrids was studied. The results of chromosome analysis on 196 cells from 15 related hybrid strains have provided the first convincing evidence that segregation of human chromosomes can be nonindependent and often concordant. Different human chromosomes were not retained with equal frequency in these hybrid clones. Some were present in 80 % of all the cells, whereas others appeared in less than 10 % of the same cells. Linear regression analysis was used to test for correlation of the frequencies of all pair-wise combinations of human chromosomes present in these hybrid clones. Twenty-two of 136 possible correlations were statistically significant, indicating that concordant segregation of particular pairs of human chromosomes is a rather frequent occurrence.
Variation in ribosomal RNA gene number in mouse chromosomes
Authors: Henderson A.S. , Eicher E.M. , Yu M.T. , Atwood K.C.
Published: May 2008

Hybridization of 125-I-ribosomal RNA to mouse chromosomes in situ produced significant differences in grain count at known rDNA sites, depending on the strains from which they were derived. This is interpreted to mean that the number of rRNA genes in a given nucleolar chromosome, and in the entire genome, is polymorphic among strains and among outbred individuals.
Sex-chromosome aberrations in wood lemmings (Myopus schisticolor)
Authors: Gropp A. , Winking H. , Frank F. , Noack G. , Fredga K.
Published: May 2008

The wood lemming displays certain peculiar features: (1) The sex ratio shows a prevalence of females (Frank, 1966; Kalela and Oksala, 1966), and some females produce only female offspring (Kalela and Oksala, 1966). (2) In a considerable proportion (in the present material, slightly less than half) of the females, an XY chromosome complement is found in the somatic tissues, but the Y is absent in the germ line of those studied (Fredga et al., 1976). Therefore, (3) a mechanism of double nondisjunction in early fetal life of XY females has to be postulated, which replaces the Y in the germ line by duplication of the X. It is assumed (4) that the X of XY females bears a sex-reversal factor that affects the male determining action of the Y (Fredga et al., 1977). There is (5) a strong presumption that in most cases the XY females are those that produce daughters only, but (6) a few exceptions may occur (Frank, unpublished observations), suggesting that the regulation according to assumption 3 (perhaps also to 4) is incomplete in XY females. In the present report, four females are described with a 31, XO karyotype, two females with 33, XYY or 32, XY/33, XYY, respectively, two males with a 33, XXY, and one male with a 32, XX/33, XXY karyotype, as observed in a consecutive series of 502 wood lemmings. The incidence of sex-chromosome anomalies in liveborn and adult animals was 2.3%; the overall incidence, including embryos, was 1.79%. Neither the somatic XO constitution nor the existence of an extra Y in females precludes fertility. However, the XXY condition in the male results in sterility. There is certain evidence that an instability of the proposed mechanism for double mitotic nondisjunction of the sex chromosomes in oogonia accounts for
The relationship between sister chromatid exchanges and chromosome aberrations in Bloom’s syndrome
Authors: Shiraishi Y. , Sandberg A.A.
Published: May 2008

The distribution of the break points of sister chromatid exchanges (SCE) was compared with that of chromosome aberrations in Bloom’s syndrome by using differential sister chromatid staining and banding techniques. A comparison was made of the distribution in chromosomes 1, 2, and 3, since the exact identification of other chromosomes is difficult with the differential sister-chromatid staining technique. It was shown that SCE and chromosome breaks do not necessarily correlate as to location. Some chromosome break points, e.g., 1q21, lp36, 2q31, 3ql2, and 3pl3, were common with those of SCE, whereas others (at 1pl3, 2pll, 2qll, and 3qll) showed little or no SCE. SCE breaks were not observed in the centromeric regions. In addition, the SCE frequency was examined in Bloom’s syndrome cells with and without chromosome aberrations, and no significant differences of SCE frequency were observed between cells with chromatid- or chromosome-type of aberrations and those with normal complements. Banding analyses indicated a nonrandom distribution of chromosome breaks in the lymphocytes and marrow cells of the Bloom’s syndrome patient.
Studies on sex chromosomes of four hamster species: Cricetus cricetus, Cricetulus griseus, Mesocricetus auratus, and Phodopus sungorus
Authors: Vistorin G. , Gamperl R. , Rosenkranz W.
Published: May 2008

In this paper, we present an analysis of the sex chromosomes of four hamster species after application of different staining techniques. The mitotic X chromosomes show a striking similarity in G-banding pattern but rather great differences in their C-banding patterns. A presumably homologous euchromatic segment that exhibits two distinct G-bands appears in the X chromosome of each species. The Y chromosome of Cricetus cricetus is in contrast to those of the other species, because it reveals a relatively well-differentiated G- and C-banding pattern. Inmeiotic metaphase I, interstitial chiasmata can be found in the sex bivalents ofCricetus cricetus and Cricetulus griseus, whereas the gonosomes of Mesocricetusauratus and Phodopus sungorus sungorus are terminally associated. The regionsthat are involved in pairing or association are always heterochromatic.
F-bodies as Y chromosome markers in mature human sperm heads: a quantitative approach
Authors: Beatty R.A.
Published: May 2008

It is generally accepted that at least some Y chromosomes in human mature sperm heads are represented in preparations by fluorescent F-bodies. From data consisting solely of F-body scorings and the visually estimated size of sperm heads from normal donors, a quantitative model is developed which permits simultaneous estimation of six parameters representing biological factors (the proportions of ploidy classes and of their sex-chromosome complements) and biassing factors (not all Y chromosomes represented by F-bodies, not all F-bodies representing Y chromosomes, and error in scoring ploidy from visual size). The analysis is statistically adequate and succeeds in predicting a variety of independently validated phenomena. The work may be regarded as a contribution to the integration of qualitative and quantitative evidence in the study of F-bodies. In all, 21,700 one-headed spermatozoa from 12 donors were scored. A mean of 54 % spermatozoa lacking F-bodies was subject to a standard deviation between donors of 4.8, over and above binomial error. Analysis yielded the following estimates: 83.3 % of diploid spermatozoa are XY, the remainder XX and YY in assumed equal number (this information assists analysis of the origin of embryonic triploidy); 2.4 % of spermatozoa are diploid (this estimate does not compete in accuracy with direct estimates from DNA absorbance); only 83 % of Y chromosomes are represented by F-bodies; 7 % of haploid heads and 14 % of diploids contain one or more “adventitious bodies” indistinguishable from true F-bodies. The visually scored head sizes “Small” and “Medium” correspond approximately with haploidy and diploidy; nearly all haploids are scored as Small, and 72% of the Medium are diploid. F-bodies are not thought at present to give a useful basis for estimating the presumably low incidence of sex-chromosome aneuploidy and nondisjunction. No such estimate has been attempted. The problem is overshadowed by not fully understood complicating factors of greater magnitude, which now appear to be a major subject of enquiry. Some implications and possible future developments are discussed.
Chromosome analysis in the Kruger National Park: the chromosomes of the bushbuck (Tragelaphus scriptus)
Authors: Wallace C.
Published: May 2008

Chromosome studies in a male and female bushbuck (Tragelaphus scriptus) are described. The male has a diploid chromosome number of one fewer than the female, and a Y-to-autosome fusion. The configuration of a quadrivalent observed in meiotic preparations from the male confirmed the presence of a fusion between a Y chromosome and an autosome. All other members of the tragelaphine tribe so far studied chromosomally show the presence of a Y-to-autosome fusion. It is postulated that the fusion observed in all present-day species of the tribe studied to date arose as a single event in a common ancestor.
A new translocation involving three chromosomes in chronic myelocytic leukemia, 46,XY,t(9;11;22)
Authors: Gahrton G. , Friberg K. , Zech L.
Published: May 2008

Bone-marrow metaphases in a 63-year-old male with newly discovered chronic myelocytic leukemia (CML) showed a complex translocation involving chromosomes 9, 11, and 22. About half of the short arm of chromosome 11 was translocated to the terminal part of the long arm of chromosome 9, and the missing fragment on chromosome 22 was translocated to the short arm of the abnormal chromosome 9. The clinical features were typical of CML, and the patient is in good physical condition 10 months after diagnosis on a regimen of busulfan.
Sex-chromosome ratios in cattle and their relationship to reproductive development in freemartins
Authors: Greene W.A. , Dunn H.O. , Foote R.H.
Published: May 2008

Nineteen “female” Holstein-Friesian calves born co-twin with a bull were purchased shortly after birth. One subsequently was judged to be a normal female with 0 % XY (100 % XX) karyotypes in cultures of blood lymphocytes. However, one typical freemartin also had 0 %XY (100 % XX) karyotypes in 300 cells when examined at three ages. Overall, 18 freemartins examined at 1, 24, and 52 weeks of age averaged 60.7 %, 57.9%, and 55.5 % XY cells, respectively (P > 0.05). No systematic relationship was found between the proportion of XY cells and the abnormalities of the reproductive organs, as judged by vaginal depth and clitoral development at 1, 24, and 52 weeks, and examination of the reproductive organs per rectum at 54 weeks of age. The clitoris of untreated freemartins and those treated with estrone or estradiol postnatally did not enlarge. Testosterone treatment caused enlargement. None of the hormones affected vaginal depth. These studies provide convincing evidence that the blood lymphocyte XX:XY karyotype ratio (1) is not related to the degree of masculinization and (2) is stabile in the postnatal freemartin. Thirdly, the freemartin reproductive organs do not respond to common sex-steroid hormones postnatally other than the clitoral response to testosterone.
Immunochemical analysis of the N-acetyl hexosaminidases in human-mouse hybrids made using a double selective system
Authors: Swallow D.M. , Solomon E. , Pajunen L.
Published: May 2008

A human-mouse hybrid, DUR 4 (Solomon et al., 1976), containing a human X/15 translocation chromosome and also chromosome 5, among other human chromosomes, was used in a double selection system to obtain hybrids of four different types: X/15+ 5+, X/15– 5+, X/15+ 5, and X/15– 5–. Standard positive and negative selection systems were used for the X chromosome, and negative selection for chromosome 5 was done with diphtheria toxin. The assignment of HEXB and the diphtheria toxin sensitivity gene to chromosome 5 was confirmed. HEXA was present only when both the X/15 chromosome and chromosome 5 were present. A “HEXA-like” band segregated with chromosome 15 (or X/15) but independently of chromosome 5. This component, unlike HEXA, does not contain human HEXβ antigen.
A comparative study of the karyotypes of eight Xenopus species and subspecies possessing a 36-chromosome complement
Authors: Tymowska J.
Published: May 2008

A comparative study of the karyotypes of eight Xenopus species and subspecies possessing a diploid number of 36 chromosomes (X.l. laevis, Xl. petersi, Xl. victorianus, X. borealis, X. gilli, X. fraseri, and X. clivii) was performed. Karyotypes based on the morphology and size of chromosomes differ only by the type and position of secondary constrictions. Some of these constrictions are nucleolar organizers, recognizable by mitotic chromosomal association. By comparing the chromosomes bearing secondary constrictions, an attempt is made to establish the cytotaxonomic relationships. The close relationship between the subspecies X.l. laevis, X.l. petersi, and X.l. victorianus is confirmed; X. borealis, however, is a separate species much nearer to X. muelleri. The karyotype of X. gilli is interpreted as being intermediate to these two groups. X. clivii could be regarded as a species close to the group of X. muelleri. X. fraseri, having a particular type of secondary constriction, is systematically more distant.
Distribution of F-bodies, heterochromatin, and nucleolar organizers in the genome of the central mudminnow, Umbra limi
Authors: Kligerman A.D. , Bloom S.E.
Published: May 2008

Due to the very limited amount of knowledge available on the cytochemistry and architecture of fish chromosomes, an extensive banding study was carried out on chromosomes of the central mudminnow, Umbra limi. Through the use of fluorescent staining, C-banding, and silver staining, the chromosomes were characterized, and an idiogram was constructed showing the location of C-band heterochromatin, F-bodies, and the nucleolar-organizer regions. G-banding was attempted but was unsuccessful. Results of fluorescent staining with 33258 Hoechst and quinacrine HCl raised some interesting questions concerning the cytochemistry of U. limi chromosomes, as well as the specificity of these stains.
Chromosomal evolution in Malagasy lemurs
Authors: Dutrillaux B. , Rumpler Y.
Published: May 2008

The chromosome analysis of meiosis in four lemurs, Lemur fulvus fulvus, L. f. collaris, L. f. albocollaris, and L. macaco, and particular hybrid crosses is reported. In metaphase I, trivalents and chain elements were detected and identified with T-banding. The study largely confirms our previous work on mitotic karyotype comparisons in the genus Lemur. The absence of chain multivalents elements in the pachytene stages of hybrid meiosis, where a chain is detected later in diakinesis, may offer evidence on the possible existence of a two-step pairing mechanism in meiotic homolog pairing. Considerations about the role of the chromosome rearrangements in establishing a gametic barrier in speciation are developed.
Distribution of constitutive heterochromatin in carnivores
Authors: Pathak S. , Wurster-Hill D.H.
Published: May 2008

The distribution of constitutive heterochromatin (C-banding) in the genomes of nine species of Felidae, one species of Mustelidae, two species of Procyonidae, one species of Viverridae, one species of Canidae, and one species of Ursidae has been studied. In the chromosomes of several felid species the C-band is apparently absent. A few chromosomes show only telomeric staining in one arm or sometimes in both arms. Centromeric and interstitial distribution of heterochromatin has also been demonstrated in other species of Carnivores, but, in general, the C-banded material in felids is comparatively less in amount, and more weakly staining, than in other mammals. Induction of C-banding patterns in certain carnivore species is rather difficult, probably because of the minimal amount of heterochromatin present.
Assignment of the gene for enolase to mouse chromosome 4 using somatic cell hybrids
Authors: D’Ancona G.G. , Croce C.M.
Published: May 2008

Somatic cell hybrids between mouse peritoneal macrophages (MPM) and human fibrosarcoma cells (HT-1080) or Chinese hamster cells (A3) were analyzed by starch-gel electrophoresis for the expression of murine enolase. Data obtained indicate that the locus for enolase is on chromosome 4 in the mouse.
Studies of the squirrel monkey, Saimiri sciureus, genome
Authors: Lau Y.-F. , Arrighi F.E. , Chuang C.R.
Published: May 2008

Cytological analysis of a squirrel monkey indicates a considerable degree of chromosomal polymorphism. DNA synthetic patterns reveal late synthesis in chromosomal segments that are C-band negative and asynchrony in DNA replication between homologs. Location of a satellite DNA with a CsCl neutral buoyant density of 1.691 g/ml was mainly in the noncentromeric constitutive heterochromatin.
Gene mapping in Mus musculusby interspecific cell hybridization: assignment of the genes for tripeptidase-1 to chromosome 10, dipeptidase-2 to chromosome 18, acid phosphatase-1 to chromosome 12, and adenylate kinase-1 to chromosome 2
Authors: Francke U. , Lalley P.A. , Moss W. , Ivy J. , Minna J.D.
Published: May 2008

Chinese hamster X mouse somatic cell hybrids segregating mouse chromosomes were examined for their mouse chromosome content using trypsin-Giemsa (GTG) banding and Hoechst 33258 staining techniques. Simultaneously, they were scored for the presence of 24 mouse enzymes. The results confirm the assignments of 11 genes previously mapped by sexual genetics: Dip-1 and Id-1 to chromosome 1; Pgm-2 and Pgd to 4; Pgm-1 to 5; Gpi-1 to 7; Gr-1 to 8; Mpi-1 and Mod-1 to 9; Np-1 and Es-10 to 14. They also confirm chromosomally the assignments of 3 genes that were made by other somatic cell genetic studies: Aprt to 8; Hprt and a-gal to the X chromosome. But most importantly, four enzyme loci are assigned to four chromosomes that until now were not known to carry a biochemical marker which is expressed in cultured cells: Trip-1 to 10; Dip-2 to 18; Acp-1 to 12; and Ak-1 to 2. Cytogenetic examination of clones showing discordant segregation of HPRT and A-GAL, suggested the assignment of a-gal to region XE→XF of the mouse X chromosome. The cytologic studies provide a comparison between data from sexual genetics and somatic cell hybrids and validate hybrid cell techniques. They provide evidence of the reliability of scoring chromosomes by GTG and Hoechst staining and stress the importance of identifying clones with multiple chromosome rearrangements. Striking examples of nonrandom segregation of mouse chromosomes were observed in these hybrids with preferential retention of 15 and segregation of 11 and the Y chromosome.
Nonpairing of the X and Y chromosomes in the spermatocytes of BDF1 mice
Authors: Rapp M. , Therman E. , Denniston C.
Published: May 2008

In the hybrid mouse strain BDF1; some 35–40 % of spermatocytes had unpaired X and Y chromosomes in stages ranging from diplotene to first meiotic metaphase. This phenomenon varied significantly from mouse to mouse. In pooled material from Swiss Albino and CF1 mice, the corresponding frequency was 5.7 %. In C57 BL/6 mice, one of the parent strains of BDFj mice, the X and Y were separate in 7.7 % of the spermatocytes. Based on the behavior of the X and Y in the BDF1 strain, it is concluded that they do not pair, rather than initially pairing and then precociously separating. The factor interfering with the pairing of the X and Y does not affect the autosomes; possibly it is an incompatibility of the two sex chromosomes, which come from different inbred lines.
Flow-cytogenetics: sources of DNA content variation among euploid individuals
Authors: Hoehn H. , Johnston P. , Callis J.
Published: May 2008

We have studied possible sources of resting human lymphocyte DNA content variation among euploid males and females as determined by flow-microfluorometry. A major source of variation arises from instrumental instability, most notably flow-rate changes. This variation can be detected and minimized by the use of chicken erythrocytes as an internal standard. A second source of variation arises from differences in rates of lymphocyte stain uptake. The lowest coefficients of variation (0.3 %) among individuals of like sex, and optimal distinction between sexes, were achieved after exposing lymphocyte samples for 24 h to the hypotonic staining solution. Four males and females with either low or high relative DNA contents within their respective sexes showed correspondingly divergent values upon repeat venipuncture. Some of the observed interindividual DNA content variation might therefore reflect truly genetic differences. For two male samples with repeatedly divergent DNA content values, preliminary C-banding of conventional metaphases suggests corresponding differences in constitutive heterochromatin.
G-band patterns of the Siberian snow sheep (Ovis nivicola) and their relationship to chromosomal evolution in sheep
Authors: Nadler C.F. , Bunch T.D.
Published: May 2008

G-band patterns of the Siberian snow sheep, Ovis nivicola alleni, 2n = 52, were compared with the patterns reported in 2n = 54 wild Asiatic mouflon and 2n = 54 North American sheep and those in domestic sheep with 2n = 54, 53, and 52. The three largest pairs of biarmed autosomes displayed indistinguishable, presumably homologous, G-banding patterns in all types of sheep. The banding and morphology of the fourth pair of biarmed autosomes in O. nivicola differed from those of the three translocation variants described in domestic sheep. Wild sheep with 2n = 54 may have evolved monophyletically from an ancestral 2n = 58–56–54 population or polyphyletically by a series of independent, nonrandom fusions. In contrast, the fourth pair of biarmed autosomes in o. nivicola and in 2n = 52 domestic sheep variants may have resulted from random fusions of different chromosomes.
Specific break points in chromosomally abnormal human fibroblast subpopulations
Authors: Benn P.A.
Published: May 2008

Common chromosome break points were found in a banding study of 25 chromosomally abnormal fibroblast clones derived from normal individuals and patients exposed to environmental carcinogens. Of 81 break points, 38 % appeared to be in terminal bands. This specificity did not appear to be the consequence of the biased recognition of exchanges. In addition, specificities for break points at exact interstitial loci were detected. The presence of clones in cultures grown in a wide variety of conditions, the finding of two identical clones in two independent lines from the same biopsy, and the absence of any obvious continuing instability in lines support the view that chromosomally abnormal fibroblasts occur in vivo.
Population kinetics of chromosomally abnormal human fibroblast subpopulations
Authors: Benn P.A.
Published: May 2008

The proportion of cells with clonally derived chromosome rearrangements has been recorded at different passage levels in 16 lines of human fibroblast cultures derived from adults. All abnormal clone populations recognized at the lowest passage levels showed a stable or declining frequency relative to the normal cells, although 2 out of the 21 clones detected did show a transient increase. Only 2 clones were found at higher passage levels that were not previously identified at low passage. The observed selection against cells with rearrangements may reflect a general property of chromosome organization which ensures that cytogenetic abnormalities do not normally accumulate in rapidly dividing tissues.
Assignment of the gene for glyoxalase I to region p21→pter of human chromosome 6
Authors: McBreen P. , Engel E. , Croce C.M.
Published: May 2008

Using somatic cell hybrids between TK-deficient mouse cells and white blood cells derived from a patient with a translocation of the region p21→pter of chromosome 17, we have assigned the gene for human GLO to region p21→pter of chromosome 6. Since the HLA region is only 10 cM distant from GLO, these results also confirm that the HLA region is located on the short arm of human chromosome 6.
Banded chromosomes of the owl monkey, Aotus trivirgatus
Authors: Miller C.K. , Miller D.A. , Miller O.J. , Tantravahi R. , Reese R.T.
Published: May 2008

Chromosomes of the owl monkey, Aotus trivirgatus, with 2n = 54, 53, or 52, have been stained to show quinacrine (Q-) and Giemsa (G-) bands, and a karyotypic arrangement has been proposed based on lengths, centromeric index, and banding pattern. C-bands were present at the centromeric region of every chromosome and over the entire short arm of certain acrocentric chromosomes; 5-methylcytosine was concentrated in the same regions. Bright Q-bands at the telomeric ends of the short arms of some chromosomes probably represent a second type of repetitive DNA. Ag-staining showed that only the chromosomes bearing a secondary constriction are nucleolus organizer chromosomes.
Association of nucleolus organizer chromosomes in domestic sheep (Ovis aries) shown by silver staining
Authors: Henderson L.M. , Bruère A.N.
Published: May 2008

The nucleolus organizer regions of domestic sheep (Ovis aries), as shown by silver staining, are located terminally on chromosomes 1, 2, 3, 4, and 25. Significant differences between individuals in the number of Ag-NORs per cell were found. The frequency of involvement of individual chromosome pairs in nucleolar organization was found to be a characteristic of individual animals. Association frequencies of individual chromosomes were accounted for by their frequency of participation in nucleolar organization. No evidence for nonrandom association of chromosome pairs was found.
The nature of the Ag-staining of nucleolus organizer regions
Authors: Schwarzacher H.G. , Mikelsaar A.-V. , Schnedl W.
Published: May 2008

Electron micrographs reveal that the Ag-stainable substance is located on the outside of NOR’s or around them but not in the chromosomes themselves. In association figures, the Ag-positive material lies between the acrocentric chromosomes. Light-microscopic studies show that the Ag stainability of the nucleolus in interphase is correlated with the function of the NOR, as seen from inactive and activated lymphocytes. Much more Ag-positive material is seen in prophase than in meta- and anaphase. It starts to increase again in late telophase. In male meiosis the NOR’s remain Ag-positive until pachytene. First and second metaphase figures are negative. Experiments using RNase, TCA, and trypsin indicate that the Ag-stainable substance is an acidic protein. The precipitation of Ag granules in interphase nuclei seen in the electron microscope is greatest over the fibrillar component of the nucleolus. The most likely interpretation is that the Ag-stainable material is a component of ribonucleic protein accumulating around active NOR’s. In mitosis some of this material remains at the NOR’s. In first meiosis it is completely removed before diakinesis.
Nucleolus organizer activity and the origin of Robertsonian translocations
Authors: Miller O.J. , Miller D.A. , Tantravahi R. , Dev V.G.
Published: May 2008

Chromosomes with active nucleolus organizer regions (NORs) were identified by combined Q-banding, C-banding (in some cases), and silver staining in mouse cell lines. NOR-bearing chromosomes were overrepresented among the chromosomes involved in Robertsonian translocations in LM(TK-), A9, and RAG cell lines. Usually only one NOR-bearing chromosome was seen in any biarmed chromosome; relatively few contained two NOR-bearing chromosomes. Thus the nucleolus plays an important role, but nucleolar fusion is relatively unimportant, in the origin of Robertsonian translocations in the mouse.
BSu restriction of DNA from cases exhibiting sex-chromosome abnormalities
Authors: Kinross J. , Fraccaro M. , Scappaticci S. , Tiepolo L. , Zuffardi O. , Pawlowitzki I.H. , Jones K.W.
Published: May 2008

The restriction endonuclease BSu, an isoschizomer of the enzyme HaeIII, cleaves human DNA to yield classes of fragments that are characteristic of the DNA of individuals having a Y chromosome. The fragments concerned are therefore diagnostic of the presence of Y-chromosome DNA and have been studied here with the intention of confirming the origin of various translocations thought, on other grounds, to involve the Y. The absence of the fragments from DNA of a case exhibiting absence of the fluorescent region of Yq suggests that the DNA concerned maps predominantly to Yq. Normal gender in the absence of the BSu fragments indicates that they do not function in sex determination.
Human somatic chromosome chains and rings
Authors: Dutrillaux B. , Croquette M.F. , Viegas-Pequignot E. , Aurias A. , Coget J. , Couturier J. , Lejeune J.
Published: May 2008

Chain and ring chromosome configurations were detected in a small percentage of the lymphocytes of a patient suffering from Thiberge-Weissenbach syndrome. Precise recognition of the chromosomes involved in the rearrangements did not indicate a systematic order of end-to-end fusions. A relationship between these configurations and the chromosome arrangement in the interphase nucleus is possible.
A cytogenetic survey of 14,069 newborn infants
Authors: Evans J.A. , Canning N. , Hunter A.G.W. , Martsolf J.T. , Ray M. , Thompson D.R. , Hamerton J.L.
Published: May 2008

A study of the chromosomes of 14,069 consecutive liveborn infants revealed 11 infants with balanced reciprocal and 13 with balanced Robertsonian translocations. A detailed physical assessment revealed no increase in major or minor malformations over control infants except for an increase in frequency of upslanting palpebral fissures and some possible minor dermatoglyphic changes. A preliminary psychologic assessment of six heterozygotes and 11 controls at 6 years of age revealed no detectable differences. The results of detailed family studies revealed only one child with an unbalanced karyotype, suggesting that where families are ascertained at random through balanced translocation heterozygotes, the frequency of children with unbalanced karyotypes is low in both the t(DqDq) and reciprocal translocation families. Fetal wastage was shown to be slightly increased in reciprocal but not in Robertsonian translocation families. In both the reciprocal and Robertsonian translocation families the segregation ratio for the translocation was not significantly different from 1:1. A significant excess of males was found among reciprocal but not among Robertsonian translocation heterozygotes. A study of the chromosomes involved in 60 reciprocal translocations ascertained at random by conventional staining in the present and two other series suggested that chromosome 11 and perhaps 13 were involved significantly more frequently than might have been expected by chance. However, with the possible exception of band ll(ql3), no “hot” spots for chromosome breakage were observed in these series. Breaks were, however, found to occur significantly more frequently in pale fluorescent, light-staining than in bright fluorescent, dark-staining bands. The importance of these findings in genetic counselling is discussed.
Fragility and spiralization anomalies of the chromosomes in three cases, including fraternal twins, with Fanconi’s anemia, type Estren-Dameshek
Authors: Schmid W. , Fanconi G.
Published: May 2008

Fraternal twins, offspring of consanguineous parents, developed pancytopenia, the boy at 7, the girl at 12 years of age. A third patient became anemic at 3 years. All three are free of associated malformations. In blood cultures the incidence of chromatid breaks, exchanges, and chromosome-type aberrations was elevated to 24 %, 18 %, and 28 %, respectively. In addition, in a low number of mitotic cells unusual observations, pointing to profound disturbances of chromosome structure, were made. It is suggested that these patients have a genetic defect impairing the normal process of mitotic chromosome condensation and decondensation.
Prenatal diagnosis in 100 structural rearrangements of the chromosomes
Authors: Boué J. , Boué A.
Published: May 2008

Among 900 couples referred for prenatal diagnosis, the indication was a parental balanced structural chromosome anomaly in 94, of which 39 were Robertsonian translocations, 38 reciprocal translocations, and 17 pericentric inversions. Six fetuses were unbalanced. The methods of ascertainment of the anomaly in these couples and the gametic segregation transmitted to the concepti are analyzed. A de novo unbalanced structural anomaly was detected in fetal cells in 6 diagnoses performed in couples referred for indications other than chromosomal.
Murine ovarian teratomas and parthenotes as cytogenetic tools
Authors: Eicher E.M.
Published: May 2008

The origin of murine ovarian teratomas and their use to estimate centromere-to-gene distances is discussed. As an example of how such a system can be used, the distance from the centromere of chromosome 7 to the Gpi-1 locus was determined by analyzing the Gpi-1 phenotypes in 47 ovarian teratomas from Gpi-1a/Gpi-1bfemales. The percent recombination was estimated to be 10.6. It is suggested that ovarian teratomas and parthenotes may be used for half-tetrad analysis.
Cytologic evidence for preferential inactivation of the paternally derived X chromosome in XX mouse blastocysts
Authors: Takagi N. , Wake N. , Sasaki M.
Published: May 2008

A total of 941 mouse blastocysts obtained from two types of crosses in which one of parents carried Cattanach’s X/autosome translocation was studied cytogenetically by quinacrine mustard fluorescence. The rearranged X (Xt) and the normal X (Xn) were distinguished by size. Karyotype analysis was successful in 721 embryos, of which 205 were heterozygous for Cattanach’s translocation. A single heterochromatic and brightly fluorescent X chromosome was identified in 154 metaphase spreads from 89 blastocysts consisting of 32–96 cells. The paternally derived X chromosome (Xp) was heterochromatic in 87 % and 88 % of the informative cells from the crosses XtXn × XtY and XtXn × χnγ; respectively. This preferential choice of Xp at the blastocyst stage might have an important bearing upon the preponderance of cells with an inactive Xp in the chorion and yolk-sac splanchnopleure.
Meiosis and fertility in XYY mice
Authors: Evans E.P. , Beechey C.V. , Burtenshaw M.D.
Published: May 2008

Four XYY male mice that showed no evidence of somatic-cell mosaicism are described. All had much reduced testis weights and considerable impairment of spermatogenesis, so that few spermatocytes survived to the second division of meiosis. In each mouse the primary spermatocytes observed were predominantly XYY, although, in two of the males, small populations of XY spermatocytes and spermatogonia were seen. However, unlike the situation in man, these XY components had failed to become dominant at the expense of the XYY cells. At diakinesis/first metaphase in the XYY spermatocytes the observed frequencies of the four possible kinds of sex-chromosome associations showed highly significant differences between males. These differences may be real or may in part be artifactual. It is suggested that conclusions drawn concerning pairing preferences of the three sex chromosomes and of their consequences as well should be treated with caution. In view of the small testis size and the few germ cells of all kinds seen in our males, we consider that in most mice the detrimental effect of the XYY constitution starts early and progresses through the seminiferous cycle rather than having a sudden effect at first anaphase, as has been previously suggested. The four males all produced some sperm, but only one gave an above-zero epididymal sperm count, and this was only 1 % of normal. This male, unlike all the previously tested XYY males, proved fertile early in life but soon became sterile. When the observations from all seven XYY males that have now been described are considered together, it is concluded that there is usually a severe impairment of spermatogenesis leading to sterility at an early age. However, the condition may have degrees of manifestation, as in man, and some XYY mice may be subfertile for a limited period rather than completely sterile.
Complementation studies with mouse translocations
Authors: Searle A.G. , Beechey C.V.
Published: May 2008

When heterozygotes for reciprocal translocations are intercrossed, the fusion of complementary unbalanced gametes normally gives fully viable, balanced zygotes. If one parent is homozygous for a genetic marker not carried by the other, the frequency of homozygous progeny resulting from such complementation can indicate whether the marker is distal or proximal to the translocation break point and thus fix the centromeric (proximal) end of the linkage group concerned. By the use of mouse translocations T(8;16)17H, T(10;18)18H, T(7;18)50H, and T(5;13)264Ca in this way, the centromeres were located at the rl, nv, nr, and dy ends of chromosomes 5, 7, 8, and 10, in line with findings by cytologic methods. Estimated frequencies of adjacent-2 disjunction (associated with complementation for interstitial segments) for T(2;9)11H, T50H, and T264Ca were 14 %, 29 %, and 12% respectively. In certain translocation intercrosses, the expected genetically marked complementation types failed to appear or else failed to survive the neonatal period. This phenomenon is associated with a maternal duplication and complementary paternal deficiency of the distal ends of chromosomes 2, 8, and possibly 7 (from other evidence). Data from other chromosomes show normal complementation, but a number remain to be tested. The possibility that haploid expression of particular maternal or paternal genes is important for normal mouse development is discussed.
G-band patterns of six species of mice belonging to subgenus Mus
Authors: Hsu T.C. , Markvong A. , Marshall J.T.
Published: May 2008

The G-band patterns of six species and one subspecies in the subgenus Mus were compared. Other than the differences in the amount and distribution of C-bands, all species had the same bands.
Comparative analysis of karyotypes in European shrew species
Authors: Olert J. , Schmid M.
Published: May 2008

The karyotypes of two closely related species of the genus Sorex (Mammalia, Insectivora) were compared with each other by G- and Q-banding techniques and by Ag-AS staining (Goodpasture and Bloom, 1975). By comparing the G-banded karyotypes, it could be ascertained that the basic differences in karyotype between the two species lie in three pericentric inversions, three paracentric inversions, and one reciprocal translocation. This is in near agreement with Ford and Hamerton (1970), who assumed that both species differ by three pericentric inversions and one tandem translocation. Furthermore, the karyotype of S. araneus (race C) presented by Halkka et al. (1974) has been compared with the S. araneus of the present report. Considering the species with respect to karyotypic evolution, it is supposed that S. araneus and S. gemelius derive from a common ancestor.
Mass production of human × rodent cell hybrids in the nude mouse — extent of chromosome and gene marker stability
Authors: Klinger H.P. , Eun C.K.
Published: May 2008

This study shows that many somatic cell hybrids can be mass produced in the nude mouse when gram quantities are required for biochemical or other studies. Of a large series of colonies and clones isolated from diploid human × mouse (A9 or RAG) and human X Chinese hamster (CHO) hybrids, the majority could grow as tumors in the nude mouse. When the chromosomes of cells of these tumors were examined, it was found that in 10 % of cases, 0 % to 5 % of the human chromosomes of the original hybrid were lost; in 70 %, between 6 % and 36 % were lost; and in the remaining 20 % of cases, between 36 % and 82 % were lost. When a human chromosome marker was detected biochemically in cells of tumors, the syntenic chromosome was always detected cytologically. The cells of daughter tumors all derived from one colony or clone generally had much greater than expected similarities in their human chromosome content, indicating that heterogeneity in the chromosome constitution of cells mass produced by this method should generally not be troublesome. Specific human chromosomes and combinations of these were lost more frequently than others, but each of the human chromosomes was retained in the cells of some of the tumors. The extent of chromosome stability appeared to be unique to each hybrid isolate. Gene products of contaminating mouse cells or fluids were sometimes detected biochemically in samples taken directly from the tumors, but not after these were maintained briefly in vitro. A few hybrids that were contaminated with mycoplasma generally failed to produce tumors in nude mice; when tumors did form, the cells had lost all or most of the human chromosomes. Thus, with noncontaminated clonal isolates the nude mouse can be used efficiently to produce large quantities of cell hybrids, which will often retain many of the human chromosomes of the original hybrid and will continue to express human gene products.
Meiotic studies in mice carrying the sex reversal (Sxr) factor
Authors: Winsor E.J.T. , Ferguson-Smith M.A. , Shire J.G.M.
Published: May 2008

A sex reversal factor (Sxr) that causes mice having apparently normal X chromosomes to become phenotypically male is transmitted in an autosomal pattern. The origin of the Sxr factor is still unknown. It seems most likely that it has originated from an autosomal gene mutation or is the result of a translocation of part of the Y chromosome to one of the autosomes. Chromosomes from four XY and six XO mice carrying this sex reversal factor were examined in the diakinesis stage of meiosis. The following unusual observations were noted: (1) in XY males carrying the Sxr factor, the X and Y chromosomes were separated more often than in controls. (2) The Y chromosome tends to be closer to an autosome when the X and Y are separate than when the X and Y are attached. (3) A chromosome fragment was present in 4/226 cells from two XO males and a single cell from an XY, Sxr carrier. Although there is no direct evidence, these observations seem to favor the possibility that the Sxr factor involves a chromosomal rearrangement rather than a single gene mutation.
The identification of a repeated DNA sequence involved in the karyotype polymorphism of the human Y chromosome
Authors: McKay R.D.G , Bobrow M. , Cooke H.J.
Published: May 2008

We show that individual men are polymorphic for the amount of two different repeated DNA sequences. The amount of one of these sequences is proportional to the length of the brightly fluorescent heterochromatin on the Y chromosome. There are no detectable alterations in sequence between polymorphic individuals. Female DNA contains sequences complementary to those found on the Y, but at a much reduced level.
Cytogenetic aspects of phylogeny in the Bovidae
Authors: Buckland R.A. , Evans H.J.
Published: May 2008

An extensive G-banding study of karyotypes of 12 species of Bovidae has been undertaken in an attempt to trace homologies and patterns of evolution of karyotype phenotypes throughout the family. G-banding profiles revealed a considerable degree of chromosome-arm homology throughout the group, which also extended into the related superfamilies, the Giraffoidea and Cervoidea. The conservation of banding patterns in chromosome arms strongly indicates that Robertsonian translocation type rearrangements have provided the major source of interspecies karyotype differences, with inversions and reciprocal and tandem translocations providing relatively minor contributions. Examples of individuals carrying newly arisen Robertsonian translocations are not infrequent, and in one instance there was evidence that two similar rearrangements had arisen independently in two species. Despite the extensive changes in karyotype organization, subfamilies within the Bovidae were characterized by the presence of common rearrangements, and those involving autosomal pairs 11 and 12 of the ox, as well as the X chromosome, separate the Bovinae from the Caprinae and Hippotraginae.
Cytogenetic aspects of phylogeny in the Bovidae
Authors: Buckland R.A. , Evans H.J.
Published: May 2008

Constitutive heterochromatin in the Bovidae, as revealed by C-banding, was mostly located in the centromeric regions. Considerable variation was, however, evident in the size of the C-bands both within and between subfamilies. Some evidence was found for a reduction in the amount of centromeric heterochromatin in bi-armed relative to acrocentric autosomes, and these findings are discussed in relation to karyotype evolution in the group.
Assignment of the gene for lactic dehydrogenase A to mouse chromosome 7 using mouse-human hybrids
Authors: O’Brien D. , Linnenbach A. , Croce C.M.
Published: May 2008

We have studied somatic cell hybrids between either mouse peritoneal macrophages or spleen cells and HT-1080–6TG human fibrosarcoma cells for the expression of mouse lactic dehydrogenase A (LDH-A). The hybrids were also studied for the expression of mouse glucose phosphate isomerase (GPI-1), the gene for which has been assigned to chromosome 7. Concordant segregation of the expression of mouse GPI-1 and LDH-1 was observed in 61 independent hybrid clones. These results indicate that the gene coding for LDH-A is located on mouse chromosome 7.
Differential frequency of human X and Y chromatin as related to cell density in vitro
Authors: Mukherjee A.B. , SanSebastian J.R.
Published: May 2008

The relationship between cell density in vitro and the frequency of fluorescent X chromatin and/or Y chromatin-positive interphase nuclei was studied in cultured cells from three human male and female subjects. It was found that although the frequency of fluorescent X chromatin-positive cells was proportional to cell density, the frequency of fluorescent Y chromatin-positive cells was independent of cell density. Our results are compared with those of other investigators.