bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on endoreduplication
Authors: Takanari H. , Izutsu K.
Published: May 2008

Cells with spontaneously endoreduplicated chromosomes were observed in tonsillar lymphocyte cultures from the second to the seventh day of culture, although at a low frequency. Cell cycle kinetics leading to endoreduplication were examined by the 5-bromodeoxyuridine (BrdU)-acridine orange method. The diplochromosomes showed four fluorescent patterns depending on the period during which BrdU was incorporated into the DNA. The kinetic data also revealed two populations among the cells with endoreduplicated chromosomes: one with a shorter (36 or 48 h) and the other with a longer cell cycle time. The existance of the latter population was shown by the fact that cell without differentially stained chromatids were observed many hours after BrdU addition (up to 120 h). This suggests that some cells with endoreduplicated chromosomes originate from cells arrested in G2.
Nucleolar organizer regions and constitutive heterochromatin in polyploid species of the genus Odontophrynus (Amphibia, Anura)
Authors: Ruiz I.R.G , Soma M. , Beçak W.
Published: May 2008

Chromosome banding patterns obtained by ammoniacal silver staining (Ag-AS) and alkaline Giemsa (CBG) have been analysed in several amphibian species of the genus Odontophrynus from South America. Ag-AS bands were found at secondary constrictions, mainly of chromosomes 4 and 11. The CBG technique revealed centromeric and telomeric constitutive heterochromatin on almost all chromosomes of these species. Moreover, intercalary bands were found at particular sites of several chromosomes. Some inter- and intra-population polymorphisms were found for the Ag-AS and C-banding patterns. The species variability in the number and position of the Ag-AS bands, known to be regions of active ribosomal cistrons, as well as the specific sites of intercalary heterochromatin, are used to discuss the possible evolutionary relationships among these species.
The gene map of the rabbit (Oryctolagus cuniculus L.)
Authors: Echard G. , Gellin J. , Benne F. , Gillois M.
Published: May 2008

A preferential loss of rabbit chromosomes was observed in 20 independent rabbit/hamster hybrid clones. Sixteen of these clones were analyzed for the enzymatic markers known to be X-linked in many species: HPRT, G6PD, PGK, GLA. These markers were shown to be syntenic, and the genes coding for them were localized on the rabbit X chromosome.
Flow sorting of the mouse Cattanach X chromosome, T (X; 7) 1 Ct, in an active or inactive state
Authors: Disteche C.M. , Carrano A.V. , Ashworth L.K. , Burkhart-Schultz K. , Latt S.A.
Published: May 2008

Cells containing the mouse T(X;7)1Ct translocation were used to separate active and inactive X chromosomes. Cytophotometric data showed that the X(7) chromosome was at least 15% larger than any normal mouse chromosome. Cloned cell lines were established from male and female embryos with a normal karyotype and carrying the X(7) chromosome in an active or inactive state as shown by replication kinetics. As expected from the cytophotometric data, flow histograms of normal mouse chromosomes stained with 33258 Hoechst had five peaks. A sixth peak was present when the chromosomes came from mice carrying T1Ct. In this peak 6, 30 to 50% of the chomosomes were X(7) and there was almost no contamination by the normal X chromosome.
Somatic pairings of the Y heterochromatin in human XYY and XYqi cells
Authors: Schmid M. , Poppen A. , Schmid W. , Engel W.
Published: May 2008

In human interphase nuclei containing Yq isochromosomes or two Y chromosomes, there are conspicuous somatic pairings between the brightly fluorescing Y-heterochromatin regions. These somatic pairings cannot be demonstrated in metaphases from conventional cell cultures because they are disrupted at the mitotic prophase. However, in lymphocytes cultivated in a medium containing distamycin A, the somatic pairing between Y-heterochromatin is preserved to metaphase. The present findings are compared with earlier observations of somatically paired heterochromatin. An explanation for the highly disparate frequency of somatic pairing between the Y-heterochromatin regions in Yq isochromosomes and YY chromosomes is proposed.
Chromosomal evolution in African megachiroptera: G- and C-band assessment of the magnitude of change in similar standard karyotypes
Authors: Haiduk M.W. , Baker R.J. , Robbins L.W. , Schlitter D.A.
Published: May 2008

Differential staining (G- and C-banding) is used to assess magnitude of chromosomal variation in eight species of African megachiropterans. These data are compared with those suggested by standard karyotypic studies, and it is concluded that in this example standard methods underestimate chromosomal variation by a factor greater than 4.5. The implication of these data is that models constructed from patterns of chromosomal evolution in standard karyotypes need to be evaluated in light of in-depth studies based on G- and C-bands.
Conservation of replication chronology of homoeologous chromosome bands between four species of the genus Cebus and man
Authors: Couturier J. , Dutrillaux B.
Published: May 2008

Replication patterns after 5-bromodeoxyuridine incorporation are analyzed in chromosomes of four species of the genus Cebus (C. capucinus, C. albifrons, C. appella, and C. nigrivittatus). They are compared with those of man, taking as reference the banding analyses previously described. It was found that the high degree of conservation of chromosome structures between Cebus and man was accompanied by conservation of the DNA-replication sequence of the bands. It is assumed that this conservation during the course of evolution may apply to other mammals. Thus, replication patterns may be useful for ensuring interspecific comparisons. The only detected difference concerns late-replicating X chromosomes from normal female cells: The predominant lymphocyte pattern described in man is rare in Cebus, in which the usual lymphocyte pattern corresponds to that of human fibroblasts or to the minor human lymphocyte pattern.
A search for a genetic basis for gonosomal univalency in mice
Authors: Gollapudi B.B. , Kamra O.P. , Blecher S.R.
Published: May 2008

The frequencies of cells with XY nonpairing at diakinesis/metaphase I were examined in random-bred ICR-Swiss, partly inbred DCH, and highly inbred DBA/2J and C57BL/6-bgJmice. The animals in a given inbred line displayed homogeneity in the proportion of cells with gonosomal univalents. In DBA/2J, the X and Y remained unpaired in 33.2% of the cells examined, whereas the corresponding frequency in C57BL/6-bgJ was only 7.0%. Previous data of Rapp et al. (1977) showed a low incidence of XY non-association in C57BL/6 and high frequencies in the BDF, hybrid (C57BL6 ♀ × DBA/2 ♂). We interpret our results, and the previous data of Rapp et al. (1977), to indicate the existence in mice of a genetic polymorphism for XY nonassociation. The DBA/2J strain appears to have factors that predispose to a high frequency of gonosomal univalency.
A complex four-break rearrangement between chromosomes 4 and 13 resulting in a recombinant chromosome 4
Authors: Andersen O. , Lundsteen C. , Niebuhr E.
Published: May 2008

A complex four-break rearrangement between chromosomes 4 and 13 was ascertained in a 10-year-old mentally retarded girl. The rearrangement was inherited from the phenotypically normal mother, who had an inverted insertion of part of the long arm of chromosome 4 into the long arm of 13 and, in addition, a pericentric inversion of the deleted 4. Meiotic crossing-over between the normal and the inverted 4 resulted in a recombinant chromosome 4, which was inherited by the proband, together with the 13/4 insertion. In this way the proband became monosomic for 4q35→qter and trisomic for 4pter→4p15, but she showed only minor physical malformations, as compared with other reports on the trisomy 4p syndrome. The cytogenetic findings were difficult to describe using the ISCN nomenclature.
Expression of silver-stained nucleolar organizing regions (Ag-NORs) in human cancer
Authors: Trent J.M. , Carlin D.A. , Davis J.R.
Published: May 2008

Five cases of ovarian adenocarcinoma, three cases of endometrial adenocarcinoma, and one case of transitional cell carcinoma of the bladder have been studied for expression of silver-stained nucleolar organizing regions (Ag-NORs). The modal chromosome number of these tumors varied from 37 to 72, with a wide range of chromosome numbers (13 to 150). The modal number of Ag-NORs in this sample varied from 3 to 7. Regression analysis among and between tumors demonstrated a proportionate increase in the number of Ag-NORs with increasing number of total chromosomes and increasing number of acrocentric chromosomes (r = 0.64 and 0.75, respectively). Modal assessment of Ag-NORs in both peripheral blood lymphocytes (PBLs) and cultured tumor cells in one patient revealed identical modes in normal and malignant cells. Also, no difference in the expression of Ag-NORs was observed between tumor cells obtained at biopsy and placed for 48 h in agar culture and tumor cells established in finite monolayer culture. Our study provides further evidence for a proportionate increase in Ag-NORs with increasing numbers of acrocentric chromosomes and total chromosomes.
The fragile site at 16q22, distamycin A, and the normal pachytene structure of chromosome 16: some possible interrelationships
Authors: Hungerford D.A.
Published: May 2008

It is possible to interpret the fragile site at 16q22 as an exaggerated expression of normal structure observed at pachytene, and to interpret the potential for such expression as a heritable trait. Exposure of cells from affected individuals to distamycin A in vitro may function to facilitate realization of this potential where the trait is not expressed spontaneously.
A pericentric inversion in the mouse
Authors: Davisson M.T. , Poorman P.A. , Roderick T.H. , Moses M.J.
Published: May 2008

A pericentric inversion induced in a Robertsonian chromosome was recovered and analyzed in a male heterozygous for the rearrangement. Identification was made from chromosome banding and confirmed by synaptonemal complex (SC) analyses. From the former, the chromosome was identified as Rb4Bnr. The inversion involves about 34% of the chromosome length, and is designated In(11.13LS)29Rk. Analysis of SC inversion loops gave break points at 0.20 in the short arm and 0.54 in the long arm. Inhibition of homologous synapsis in the inversion was observed at zygotene and early pachytene, while synaptic adjustment was found to lead to heterologous SC formation at late pachytene. The inversion is believed to be causally related to the reduction in fertility observed in the carriers.
Cytological similarity between the heterochromatin of the large X and Y chromosomes of the soft-furred field rat, Millardia meltada (family: Muridae)
Authors: Nanda I. , Raman R.
Published: May 2008

Patterns of DNA replication, fluorescence, and meiotic pairing have been studied in the composite X and Y chromosomes of a rodent, the soft-furred field rat, Millardia meltada. The heterochromatin of both the chromosomes replicates during late S and fluoresces brightly with Netropsin-Olivomycin. The fluorescence with Actinomycin D-Hoechst is dull, suggesting that the heterochromatin of both the X and the Y is relatively GC-rich. When surface-spread testis cells are analysed after silver staining considerable portions of the X and Y exhibit synapsis. On the basis of this study it appears that the heterochromatin of the X chromosome of M. meltada is substantially similar to that of the Y chromosome.
H-Y antigen as a tool for the determination of the heterogametic sex in Amphibia
Authors: Engel W. , Schmid M.
Published: May 2008

H-Y antigen was investigated in three amphibian species with different degrees of sex-chromosome differentiation: Bujo bufo, Triturus vulgaris, and Pyxicephalus adspersus. No heteromorphic sex chromosomes were found in B. bujo, but an examination of the progeny of hermaphrodites (Ponse, 1942) indicated that the female of this species was heterogametic (ZW). Sex chromosomes differing only by a very small heterochromatic region at their telomeres were found in the male of T. vulgaris (XY). Pyxicephalus adspersus revealed highly differentiated ZW sex chromosomes. The results of the H-Y antigen studies on these three species indicate that H-Y antigen is expressed only in the heterogametic sex, irrespective of differences in morphological differentiation of the sex chromosomes. Therefore, H-Y antigen could be a valuable tool in determining the heterogametic sex, not only in Amphibia but possibly also in other vertebrate species that have either evolved no heteromorphic sex chromosomes or where sex-reversal experiments are not possible.
Cattle gene mapping by somatic cell hybridization study of 17 enzyme markers
Authors: Heuertz S. , Hors-Cayla M.-C.
Published: May 2008

In 38 independent hamster-bovine hybrids, the segregation of 17 bovine enzyme markers was studied. The results showed three syntenic groups; LDHB-PEPB-TPI, PGM3-ME1-SOD2, and PGD-ENOl, whereas nine other markers did not show any syntenic relationship: LDHA, MDH2, LDH1, SOD1, PKM2, PGM1, PGM2, AK1, and MPI.
The effect of gamma irradiation of human cells and somatic cell hybridization on sister chromatid exchange frequencies in the hamster chromosomes of hamster-human hybrid lines
Authors: Wang H.S. , Christie N. , Hamerton J.L.
Published: May 2008

Sister chromatid exchange (SCE) frequency was studied in human/hamster hybrid lines in which the human cells had been exposed to gamma irradiation at doses of 0, 10, 20, and 40 grays. A higher SCE frequency was found in the hamster chromosomes in the hybrid lines than was found in the hamster parental cell line CHW1103. There was also a dose-dependent increase of SCE frequency in the unirradiated hamster chromosomes in the hybrid lines in which the human parental cells had been irradiated.
Gametogenesis in a male Indian muntjac × Chinese muntjac hybrid
Authors: Liming Shi , Pathak S.
Published: May 2008

Histological and cytogenetic examinations of testicular preparations from a male hybrid between an Indian muntjac × Chinese muntjac showed a certain degree of chromosomal homology, as evidenced by the synaptic behavior. The male hybrid is considered sterile because spermatogenetic stages were arrested at early prophase. Silver staining demonstrated that the nucleolus organizer regions of both parents were expressed, but no synaptonemal complex and sex vesicle were observed.
Sheep gene mapping by somatic cell hybridization: four syntenic groups: ENO1-PGD, ME1-PGM3, LDHB-PEPB-TPI, and G6PD-PGK-GALA
Authors: Saïdi-Mehtar N. , Hors-Cayla M.-C. , van Cong Nguyen
Published: May 2008

Gene segregation for 16 ovine enzyme markers was studied in 25 independently derived hamster-sheep hybrids. The results show four syntenic groups, ENOl-PGD, ME1-PGM3, LDHB-PEPB-TPI, G6PD-PGK-GALA, and markers for six different chromosomes: PGM1 (or PGM2?), IDH1, GPI, LDHA, MDH2, and ADA.
Translocation (5p;17q) in blast crisis of chronic myeloid leukemia
Authors: Hagemeijer A. , Sizoo W. , Smit E.M.E. , Abels J.
Published: May 2008

A new abnormality of chromosome 17, distinct from i(17q), was observed in bone marrow cells of two patients with CML during a blast crisis. The marker was identified as a translocation of the short arm of chromosome 5 onto the long arm of chromosome 17, i.e., t(5p;17q). In one case, the marker was clearly dicentric. The clinical history of these two patients showed some similarities. A slightly different marker has previously been observed in a cell line derived from a solid tumor.
The pattern of early replicating bands in the chromosomes of the mouse
Authors: Somssich I. , Hameister H. , Winking H.
Published: May 2008

Early replication of mouse chromosomes was studied with the BrdU-Hoechst-Giemsa technique. With the help of different Robertsonian translocation chromosomes as markers, chromosomal bands that replicate early were identified. An idiogram of each chromosome was constructed. The array of replicating bands along the chromosomes fits well into the existing nomenclature based on G-banding. The karyotype presented is useful for R-banding studies as well.
A cyclical translocation, t(1;8;5), in the domestic chicken (Gallus domesticus)
Authors: Bitgood J.J. , Otis J.S. , Shoffner R.N. , Fechheimer N.S.
Published: May 2008

A chromosome analysis of a translocation in the domestic chicken (Gallus domesticus) revealed that it was a cyclical translocation involving chromosomes 1, 5, and 8. Meiotic preparations showed a ring-of-six, and G-banding verified that a portion of 1p was translocated to 8q, a portion of 8q was translocated to 5q, and a portion of 5q was translocated to 1p.
Chromatid lesions and chromatid core morphology
Authors: Satya-Prakash K.L. , Hsu T.C. , Pathak S.
Published: May 2008

A silver-staining technique revealed the core morphology of metaphase chromosomes of irradiated CHO cells with chromatid lesions (breaks, gaps). These cells were photographed before and after silver staining. As a rule, the core was not continuous in chromatid gaps, suggesting that the chromatid is broken in many so-called gaps. Ten cytogeneticists who were asked to classify chromatid gaps and breaks from photographs of chromosome lesions before silver core staining agreed in only 19 of 53 cases.
Robertsonian polymorphism in chromosomes of Oryzomys subflavus(Rodentia, Cricetidae)
Authors: Maia V. , Hulak A.
Published: May 2008

Eighty-four specimens of Oryzomys subflavus, collected in the State of Pernambuco, Brazil, were studied. A Robertsonian chromosome polymorphism, characterized by a varying diploid number of 50, 49, 48, and 46, was found. All the specimens showed a chromosome arm number of 56. G-banding patterns in somatic cells allowed identification of the chromosome pairs (2, 3, 5, and 7) involved in centric fusion. C-banding revealed the presence of constitutive heterochromatin near the centromere the X chromosome and those of the autosomes. The Y chromosome presented a large heterochromatic block in the distal portion of its long arm.
Conserved autosomal syntenic group on mouse (MMU) chromosome 15 and human (HSA) chromosome 22: assignment of a gene for arylsulfatase A to MMU 15 and regional mapping of DIAl, ARSA, and ACO2 on HSA 22
Authors: Francke U. , Tetri P. , Taggart R.T. , Oliver N.
Published: May 2008

We have utilized a panel of Chinese hamster × mouse somatic cell hybrids segregating mouse chromosomes to assign a gene for arylsulfatase A (ARSA) to mouse chromosome 15. Considering our previous assignment of a gene for diaphorase-1 (DIAl) to the same mouse chromosome, we have evidence for another syntenic relationship that has been conserved, since the homologous loci for human ARSA and DIAl are both located on human chromosome 22. Because MMU 15 and HSA 22 are quite dissimilar in size and banding patterns, we have attempted to identify the conserved portion by regional mapping of human DIAl and ARSA using somatic cell hybrids segregating a human chromosome translocation t(15;22)(q14;q13.31). The results assign human DIAl and ARSA to the distal sub-band of 22q13 (region 22q13.31→qter). The locus for mitochondrial aconitase (ACO2) has been separated by the breakpoint from DIAl and ARSA and is located more proximally.
The influence of strain, maternal age, and method of maturation on mouse oocyte aneuploidy
Authors: Golbus M.S.
Published: May 2008

The chromosome complement of metaphase II oocytes matured by different methods was determined. These oocytes were collected from young and old Swiss-Webster random bred and CBA inbred mice. The results from the two strains were remarkably similar. Superovulation caused no increase in aneuploidy frequencies; however, in vitro maturation resulted in increased hyperploidy rates for oocytes from younger females of both strains. Of the six possible comparisons regarding a maternal age effect, there were no significant increases in hyperploidy. The absence of a maternal age effect on the first meiotic division of oocytes, while such an effect does exist for mid-gestation mouse fetuses, suggests that the maternal age effect on aneuploidy may be due to a decreased ability to select against (abort) aneuploid embryos/fetuses as a function of increasing maternal age.
Improved autoradiographic procedure for cytogenetics: inverted coverslips and double illumination
Authors: Stoll M. , Cardoso H.
Published: May 2008

The method described here has the advantage of presenting a clear image of both chromosomes and silver grains. Chromosomes are stained through the emulsion with Hoechst 33258. As two different sources of light are employed—epi-ultraviolet illumination and transmitted visible light—a separate photographic record of each optical plane can be obtained of chromosomes, silver grains, and chromosomes and grains together.
Reaggregation of rat gonadal cells in vitro: experiments on the function of H-Y antigen
Authors: Müller U. , Urban E.
Published: May 2008

Dispersed cells of the gonads of newborn rats reaggregate histotypically in rotation culture. Ovarian cells form follicles, while testicular cells organize tubuli. When testis cell supernatant is added to ovarian cells, they form tubulus-like structures. This effect is impeded by simultaneous addition of monoclonal anti-H-Y antibody. It is concluded that H-Y antigen is the active factor of testis cell supernatant that induces sex-reversal of ovarian cells in vitro. The reverse experiment, i.e., exposure of testicular cells to anti-H-Y antiserum, does not result in the organization of follicular structures. These findings are consistent with the view that H-Y antigen is involved in testis differentiation by inducing testis cell-specific functions, rather than by cross-linking cells.
Evidence for heteromorphic sex chromosomes in male amphibians (Anura: Leptodactylidae)
Authors: Iturra C. P. , Veloso M. A.
Published: May 2008

In Eupsophus migueli, an anuran species endemic to southern Chile, all males examined have a heteromorphic pair of chromosomes, a small metacentric and a telocentric of the same size. In females, the corresponding pair, No. 14, is telocentric. This suggests that this species has an XX/XY system of sex chromosomes. The male is the heterogametic sex.
Catalase levels in patients with aniridia and/or Wilms’ tumor: utility and limitations
Authors: Ferrell R.E. , Riccardi V.M.
Published: May 2008

The gene for red blood cell (RBC) catalase has recently been mapped to 11p13, and a gene dosage effect has been demonstrated for individuals with triplication or deletion of that region. Deletion of the 11pl3 band has also been associated with aniridia, with and without Wilms’ tumor. We studied the RBC catalase levels in individuals without detectable chromosomal abnormalities but with aniridia, Wilms’ tumor, and the combination of aniridia and Wilms’ tumor, to determine whether catalase levels might provide evidence for a sub-microscopic chromosomal deletion in the 11p13 region. All karyotypically normal patients were found to have normal catalase levels.
Sequence of centromere separation: an analysis of mitotic chromosomes from long-term cultures of Potorus cells
Authors: Vig B.K.
Published: May 2008

The sequence of centromere separation in late metaphase/anaphase cells from a long term culture of cells from a male rat-kangaroo, Potorus tridactylus, was studied. The karyotype of the PTK-1 line has five pairs of autosomes, one modified No. 1 (M1), and X, Y1 and Y2. In 87% of the cells the centromeres of No. 4 or 5 were among the first to separate. Y1, Y2, X, or the marker, M1, were not the earliest chromosomes to separate. Y2 separated last most frequently (59%), followed by X, M1 and Y1. The overall relative averages for the sequence of separation in the entire genome (centromere separation index or CSI) are 1.52, 1.40, 1.11, 0.92, 0.88, 0.86, 0.68, 0.56, and 0.27 for 5, 4, 2, 1, Y1, 3, M1, X, and Y2, respectively (the average for the whole genome is 1). The data indicate that the centromeres of the chromosomes of Potorus separate in a specific, genetically controlled, non-random sequence. The chromosomes separating late have larger amounts of centromeric heterochromatin; all of this or part of it may be the controlling element for the sequence of separation.
Chiasma frequency and distribution in a sample of human males: chromosomes 1, 2, and 9
Authors: Laurie D.A. , Hultén M. , Jones G.H.
Published: May 2008

Chiasma frequency and the distribution of chiasmata within chromosomes 1, 2, and 9 were investigated in a total of seven males with presumptively normal meiosis. With the exception of one unusual individual, there was little variation among the males examined for these characteristics. The exceptional male had a reduced chiasma frequency, which, rather than being considered abnormal, was thought to represent the lower end of the normal range of variability. A statistical analysis of the histograms of chiasma distribution confirmed the impression of overall similarity, and we conclude that genetic maps of these chromosomes may now be constructed without too much disturbance from differences between individuals. The maps will be presented separately in a subsequent paper.
Distribution of C-band heterochromatin in the ZW sex chromosomes of European and American eels (Anguillidae, Teleostomi)
Authors: Park E.-H. , Grimm H.
Published: May 2008

The ZW sex chromosomes of the European eel, Anguilla anguilla, and the American eel, A. rostrata, were examined with C-band and fluorescent staining to demonstrate the C-band heterochromatin. The W as well as Z chromosomes in both species are C-band negative except for a small amount of C-band heterochromatin in the centromeric region, in contrast to the W or Y elements of most other vertebrates. No fluorescing W-associated body is evident either in interphase nuclei or in metaphase plates. The ZW chromosomes of the two species have substantially similar size, morphology, and patterns of C-band heterochromatin. Karyologic and evolutionary implications are discussed.
A unique Y/Y translocation in an infertile male
Authors: Butler M.G. , Sanger W.G. , Walzak M.P.
Published: May 2008

A monocentric and submetacentric Y/Y translocation without evidence of mosaicism was observed in a male with tall stature and azoospermia. Chromosome measurements of the abnormal Y of this patient and the normal Y of his father were undertaken to determine more precisely the chromosome break points in this translocation. The measurements failed to show a definite loss of chromatin from the original short arm of the proband’s Y chromosome. The azoospermia and infertility in our patient, in contrast to his father, suggest that infertility may be associated with this specific Y/Y translocation in human males.
Chromosome localization of three syntenic gene pairs in the American mink (Mustela vison)
Authors: Rubtsov N.B. , Radjabli S.I. , Gradov A.A. , Serov O.L.
Published: May 2008

Twenty eight American mink × Chinese hamster somatic cell hybrids were analysed for the expression of mink enzymes and for mink chromosomes. The results of this analysis made it possible to assign the genes for phosphoglucomutase-1 and phosphogluconate dehydrogenase to chromosome 2, those for lactate dehydrogenase A and glucose phosphate isomerase to chromosome 7, and those for lactate dehydrogenase B and triosephosphate isomerase to chromosome 9.
An assessment of the nature of chromosomal rearrangements in 18 species of Peromyscus (Rodentia: Cricetidae)
Authors: Robbins L.W. , Baker R.J.
Published: May 2008

G- and C-banded karyotypes from 9 previously unstudied species of Peromyscus are described and compared to the 9 species described in the literature. Additional new data are presented for P. eremicus. A hypothetical evolutionary tree for the 18 species was constructed based on the assumption that, where possible, shared chromosomal rearrangements became established in a common ancestor. A minimum of 60 chromosomal rearrangements (34 heterochromatic additions and 26 pericentric inversions) were needed to construct the most parsimonious tree. Seven of the 18 species have heterochromatin in noncentromeric areas. Three times as many inversions have been identified in the 11 largest pairs as have been observed in the 12 smallest pairs. Peromyscine rodents are characterized by a pattern of chromosomal variation quite distinct from that described for other rodent genera, such as Sigmodon and Mus. Karyotypic orthoselection in rodents appears to be relatively common in closely related species.
Genetic analysis of tumorigenesis
Authors: Howell N. , Sager R.
Published: May 2008

Intraspecies somatic cell hybrids of BALB/c mouse 3T3 and SV40-transformed embryonic fibroblast (SVT2) cells were analyzed for transformation-associated properties and their tumorigenic potential in nude mice. In confirmation of our earlier findings, hybrids expressing the viral T-antigen were not suppressed for the ability to clone in medium with 1% serum. In contrast, division rate in medium with 1% or 10% serum, anchorage independence, cytochalasin-sensitive growth control, and tumorigenicity were suppressed noncoordinately, and the extent of suppression varied from one hybrid to another. Suppression was not simply determined by the increased chromosome content of the hybrid cells, nor was suppression correlated with rearrangements of the integrated viral sequence (Sager et al., 1981a, b). Similar results were found in cytoplasmic transferants expressing T-antigen. Four independent transferants and subclones derived from them varied in the extent of suppression of anchorage independence and tumorigenicity. In both hybrids and transferants, a low serum requirement for clonal growth apparantly was determined solely by expression of SV40 T-antigen, but other transformation properties, as well as tumorigenicity, appeared to require multiple changes in the cellular genome for their expression. These changes must occur during or after viral integration, since they are not expressed in uninfected 3T3 cells.
Comparative gene mapping of man and Cebus capucinus: a study of 23 enzymatic markers
Authors: Créau-Goldberg N. , Cochet C. , Turleau C. , de Grouchy J.
Published: May 2008

A total 23 enzymatic markers were analyzed in cell hybrids obtained between Cebus capucinus (CCA) fibroblasts and a Chinese hamster cell line. The following markers, or syntenic groups, could be localized in CCA chromosomes homologous to human chromosomes or chromosome segments: PGD-ENOl-PGMl, MDH1, IDH1, PGM2, PGM3-ME1, AK3, TPI-LDHB-PEPB, GPI, and SODl. The following syntenic groups were observed but could not be localized: GUK1-FH and MPI-PKM2. The following loci could not be localized with full confidence: LDHA, NP, PEPD, ITP, and PGK.
Differential fluorescent staining of porcine heterochromatin by chromomycin A3/distamycin A/DAPI and D 287/170
Authors: Schnedl W. , Abraham R. , Förster M. , Schweizer D.
Published: May 2008

R banding of porcine chromosomes by chromomycin A3 plus distamycin A and DAPI (DA-DAPI) revealed two distinct types of heterochromatin: The GC-rich centromeric heterochromatin of the biarmed autosomes (Nos. 1–12) and of the X chromosome exhibited bright chromomycin A3 fluorescence, while the heterochromatin of the acrocentric chromosomes (Nos. 13–18) stained brightly by DA-DAPI. The latter also fluoresced brightly when stained by D 287/170. In addition, significant fluorescent polymorphism was observed among both acrocentric and metacentric chromosomes.
The contribution of chromosome aberrations to the precision of human gene mapping
Authors: Ferguson-Smith M.A. , Aitken D.A.
Published: May 2008

Unbalanced chromosome aberrations detected by routine chromosome diagnostic services can be used for gene mapping by gene dosage. This procedure, once discredited by early observations in Down’s syndrome, has now provided some of the most precise intrachromosomal gene localizations known and these are reviewed. Cytogeneticists have an obligation to see that every opportunity is taken to obtain mapping information from suitable cases. Interpretation of cytogenetic findings may be improved by application of appropriate gene dosage studies, and examples are described in which a diagnosis was made possible by such studies. Cytogeneticists may also contribute to human gene mapping by application of the technique of in situ molecular hybridization. The localization of the immunoglobulin kappa light chain genes (IGKV) to the short arm of chromosome 2 reported at this workshop provides the first example of the localization of an unassigned, unique DNA gene sequence by this method. Combined with the use of chromosomal translocations, resolution of assignments to chromosomal sub-bands is possible, and, as suitable DNA clones become available, the technique should have wide applicability in human gene mapping.
Difficulties in assessing the human health effects of mutagenic carcinogens by cytogenetic analyses
Authors: Wolff S.
Published: May 2008

The analysis of induced chromosome aberrations in the peripheral lymphocytes of irradiated people is a reliable method for determining exposure to ionizing radiations. The system should also work for S-independent chemicals. For the majority of chemical clastogens, which are S-dependent, however, the utility of the system is far less certain because DNA repair can remove many of the adducts before the cells enter S. Sister chromatid exchanges are sensitive indicators of S-dependent mutagens; however, because of DNA repair, great interpersonal variability of response, and variability of reference populations, it has not yet been proved that they can be used to monitor populations for low-level chronic exposure. In any case, these cytogenetic tests can only be used to estimate the risk to the population as a whole. They cannot be used to predict whether a given person will suffer any particular form of ill health.
The chromatid gap — a useful parameter in genotoxicology?
Authors: Brøgger A.
Published: May 2008

Chromatid gaps occur as two morphologically indistinguishable types—the clastogenic (DNA damage) type and the turbagenic (no DNA damage) type—and are induced by many genotoxins in a dose-dependent way. Gaps may serve as a low-dose sentinel parameter in genotoxicology. However, their usefulness is limited until further studies have shown whether the turbagenic substances that cause gaps are all capable of inducing segregational errors. In genetic toxicology testing and monitoring, methanol/acetic acid-fixed and air-dried preparations are stained in Giemsa and are then studied under the light microscope. With this method gaps and breaks cannot be distinguished unambigously and should therefore be scored in the same class of aberrations.
The use of inhibitors of DNA repair in the study of the mechanisms of induction of chromosome aberrations
Authors: Preston R.J.
Published: May 2008

If cells exposed to X-rays or chemical agents are incubated with inhibitors of DNA repair (cytosine arabinoside or aphidicolin), it is possible to accumulate single-strand gaps in the DNA at repairing regions. Upon reversal of the inhibition, these gaps can interact to form chromosome aberrations. It appears that the aberration frequency observed following treatment with radiation or chemical agents is greatly influenced by the rate of repair of damage that is converted into aberrations. This argument also extends to considerations of the different cell-cycle-stage sensitivities, the relative sensitivities of different species, and the probability of observing interactive effects between two agents. These aspects are discussed in terms of their contribution to the interpretation of the mechanisms of induction of chromosome aberrations.
Hyperthermic potentiation of chromosome aberrations by anticancer antibiotics
Authors: Vig B.K. , Cornforth M. , Farook S.A.F.
Published: May 2008

In view of the success of hyperthermia as a modality in cancer treatment, we have studied its effect on chromosomes in combination with anticancer antibiotics. Three classes of chemicals, one with a non-delayed type of effect (adriamycin), one with a delayed type of effect (mitomycin C), and one with a truely radiomimetic effect (bleomycin) were selected for study on human lymphocytes and Chinese hamster K-l cells. Propane sultone was also included because its effect on plants is suppressed by hyperthermia. The data show increased potential of these chemicals to induce chromosome aberrations when applied at temperatures higher than 37° C, irrespective of the phase of cell cycle. The potentiation may be due to true synergism (bleomycin) or facilitation of entry of larger quantities of the drug (adriamycin). No potentiating effect was observed on the induction of sister chromatid exchanges (SCEs).
Sister chromatid exchange and gene mutation
Authors: Carrano A.V. , Thompson L.H.
Published: May 2008

The parallel induction of sister chromatid exchange (SCE) and single-gene mutation was quantified in Chinese hamster ovary cells following exposure to nine different physical or chemical agents representing a wide variety of inducing lesions. For each agent, the frequency of induced SCE was linearly related to the induction of mutation, but the efficiency of SCE formation relative to mutation induction differed for each. Studies in repair deficient cells suggested that unrepaired lesions enhanced the induction of both SCE and mutation but that the degree of enhancement was not necessarily the same for both endpoints.
Mouse spermatogonia and spermatocyte sensitivity to chemical mutagens
Authors: Adler I.-D.
Published: May 2008

Twenty-one chemicals have been tested for the induction of chromatid aberrations in differentiating spermatogonia, and 14 of them gave a positive response. However, when spermatocytes derived from treated As-spermatogonia were analyzed for reciprocal translocations, the results were negative for 10 out of 17 chemicals tested. For the remaining 7 chemicals, either conflicting results or no dose dependency has been reported. The difference between aberrations in differentiating spermatogonia and the lack of translocations in spermatocytes after treatment of stem-cell spermatogonia was most obvious with mitomycin C. Reasons for this difference are discussed. In meiotic prophase, mitomycin C and TEM caused aberrations observable at diakinesis only after treatment of spermatocytes in S-phase. In contrast, ionizing radiation produces its main effect during pachytene. Translocation heterozygotes were recovered among progeny of mitomycin C- and TEM-treated spermatocytes. Conclusions for human health hazards are: (1) chromosomal aberrations induced by chemical mutagens in spermatogonia do not pose a considerable risk because they do not sufficiently survive germinal selection; (2) chemical treatment of spermatocytes can result in chromosomally abnormal offspring. The quantification of human ill health based on translocation yields obtained in animal experiments poses great difficulties that have not been resolved.
Genetically determined chromosome instability syndromes
Authors: Schroeder T.M.
Published: May 2008

Spontaneously increased chromosomal instability is well documented in the three autosomal recessive diseases, Fanconi’s anemia (FA), Bloom’s syndrome (BS), and ataxia telangiectasia (AT). Other conditions have been reported to be associated with chromosomal breakage. Some are still single observations: in Werner’s syndrome only fibroblasts are affected, and systemic sclerosis may not be an inherited disease. Various aspects of FA, BS, and AT are discussed which have emerged since recent reviews have been published. The differential diagnosis in FA has become more important than it was in the past. Proven heterogeneity in FA demands definition of what to name FA and FA variants. The analysis of cancer frequencies and types in FA and AT lacks important clues. This should stimulate all of us to mutual exchange of data and creation of registries not only of patients and followups, but also of characterized cell strains. A synopsis of results from cell and cytogenetic studies demonstrates similarities and differences in detail of the general phenomenon of chromosomal instability which FA, BS, and AT share. Results from biochemical studies at the DNA level together with cytogenetic findings indicate different but still undefined failures in DNA metabolism or DNA repair mechanisms due to the different genes. A new approach to analyzing the impairment of DNA repair in FA is briefly described. DNA related enzymes are produced in the cytoplasm and have to be transported to the nucleus. The subcellular distribution of topoisomerase activity was found to be unusual in three placentas of FA patients. Other DNA enzymes were distributed normally. Thus, a specific mechanism for movement of the enzyme through the nuclear membrane seems to be defective.
Cytogenetic and flow cytometric studies of cells from patients with Fanconi’s anemia
Authors: Latt S.A. , Kaiser T.N. , Lojewski A. , Dougherty C. , Juergens L. , Brefach S. , Sahar E. , Gustashaw K. , Schreck R.R. , Powers M. , Lalande M.
Published: May 2008

Cells from patients with Fanconi’s anemia are unusually sensitive to agents which are capable of crosslinking DNA. This increased sensitivity can be detected both by cytogenetic and flow cytometric methods. An elevated frequency of chromosome aberrations, which is further exaggerated by exposure of cells to DNA crosslinking agents, is a general feature of Fanconi’s anemia. Information about the formation of sister chromatid exchanges in this disease is less consistent. Cytogenetic analysis of cells from patients with Fanconi’s anemia can be compromised by a low mitotic index. This is reflected in an accumulation of cells in the G2 phase of the cycle, after exposure to the bifunctional alkylating agent, mitomycin C. New methods for differentiating individuals with Fanconi’s anemia from unaffected individuals should be of empirical use and might also facilitate mechanistic studies of this disease.
Structural changes in chromatin as the basis for radiosensitivity in ataxia telangiectasia
Authors: Painter R.B.
Published: May 2008

Cells from patients with the autosomal recessive genetic disease ataxia telangiectasia (AT) are more sensitive to killing by ionizing radiation than are cells from normal individuals. In contrast, ionizing radiation inhibits the rate of DNA synthesis much less in AT cells than in normal cells. This radioresistant DNA synthesis can be partly mimicked by treating normal cells with caffeine or by incubating normal cells in hypertonic medium after irradiation. Because both of these treatments seem to affect chromatin structure, it is possible that the radioresistant DNA synthesis in AT cells is due to an intrinsic difference in chromatin structure between AT cells and normal cells. This difference allows normal cells to recognize chromatin damage and to pause and repair it, whereas AT cells fail to recognize this damage, which leads to chromosomal aberrations.
Attempts to detect ataxia telangiectasia (AT) heterozygotes by cytogenetical techniques
Authors: Natarajan A.T. , Meijers M. , van Zeeland A.A. , Simons J.W.I.M.
Published: May 2008

AT cells are known to be more sensitive than normal human cells to ionizing radiation as well as other agents, as judged by cell survival, induced chromosomal aberrations, and micronuclei. The inhibition of DNA replication following X-irradiation is less in AT cells than in normal cells. Four different cell lines heterozygous for AT were investigated for their response to various treatments in order to see whether they behaved in an intermediate way. In most of the tests, the heterozygous AT cells behaved like normal cells. In the frequencies of induced chromosomal aberrations following X-rays, there was heterogeneity in response, with one cell line showing a definite intermediate response.
Genetic factors that affect rates of spontaneous mutation and chromosome aberrations in Drosophila melanogaster
Authors: Woodruff R.C. , Thompson, Jr. J.N.
Published: May 2008

Several important human syndromes provide evidence for the idea that the rate of gene mutation and chromosome breakage is under genetic control. Although not understood in detail, their underlying mechanisms include deficiencies in DNA replication, repair, and increased sensitivity to external agents. The ease of genetic analysis in Drosophila melanogaster offers a number of model systems that may give useful insights into comparable human conditions. For example, some of the many meiotic mutants isolated from natural populations provide information on the genetics of DNA repair in a eukaryote. In addition, complex syndromes affecting mutation rate are available for study. One such system is hybrid dysgenesis in Drosophila. Hybrid dysgenesis refers to a collection of genetic changes, including chromosome breakage, increased mutation rates, and sterility expressed in crosses between independent population lines. Our recent work has focused upon chromosome breakage and mutator activity in this system. The pattern of inheritance and expression of mutator activity implicates a chromosome-cytoplasm interaction for its induction. Furthermore, the genetic elements responsible for this phenomenon appear to move from one location or chromosome to another. Indeed, one can draw a convincing parallel between hybrid dysgenesis and the behavior of transposable, or nomadic, DNA sequences. Thus, one must view the phenotype “mutation rate” as a conglomerate of factors affecting DNA stability, physiological condition, and the behavior of genetic elements.
Chromosomal instability of SV40-transformed human prostatic epithelial cell lines
Authors: Ohnuki Y. , Lechner J.F. , Bates S.E. , Jones L.W. , Kaighn M.E.
Published: May 2008

Three SV40-transformed derivatives (Tl, T2, and T5) of human prostatic epithelial cells were analyzed karyotypically. For comparison, an SV40 derivative (TA) obtained from isogenic fibroblasts, was also studied. The chromosome complements of these cells, as well as a subclone of T2 isolated in soft agar (T2-A5), were analyzed using banding techniques. Numerical as well as structural changes were observed in all transformed cultures. Karyotypic changes in all cells at a given passage level appeared to be random. On the other hand, characteristic differences in modal chromosome number, and type and number of abnormal chromosomes were observed among the different lines. Most cells of two of the three epithelial lines (Tl and T2) were either hypo- or pseudodiploid, whereas T5 consisted of a mixed hypodiploid and hypotetraploid population. The TA subline was also predominantly hypo- and pseudodiploid. Dicentrics, telomeric associations, translocations, and loss of chromosomes were the most prominent abnormalities. The loss of chromosome 18 was characteristic for all epithelial lines. All Tl and T5 cells had lost either one or both copies of the 18. While individual cells of the original T2 line had random karyotypes, most of T2-A5 cells had a relatively uniform karyotypic pattern. They also had a similar pattern of abnormal chromosomes. These observations suggest that culture in soft agar may have selected a particular chromosomal variant. We conclude that transformation of prostatic epithelial cells by SV40 may bring about site-specific as well as random chromosomal changes. These changes could reflect either intermediate or sequential stages in progression to neoplasia.