bluuebunny/crossref_metadata_2025 huggingface dataset:
Retinoblastoma, chromosome 13, and in vitro cellular radiosensitivity
Authors: Nove J. , Little J.B. , Weichselbaum R.R. , Nichols W.W. , Hoffman E.
Published: May 2008

Five diploid fibroblast strains from patients with deletions mapping in the long arm of chromosome 13 and three strains bearing partial trisomies of chromosome 13 were assayed for clonogenic survival following X-irradiation. Results of these experiments suggest the existence of a region on 13ql4 which is related to increased sensitivity to cell killing in vitro by X-rays. This locus seems to be distinct from but close to the retinoblastoma locus, which has been associated with the same band.
Aniridia-Wilms’ tumor association: evidence for specific deletion of 11p13
Authors: Francke U. , Holmes L.B. , Atkins L. , Riccardi V.M.
Published: May 2008

A 7-year-old boy with aniridia, Wilms’ tumor, and mental retardation, previously reported as having an interstitial deletion of the short arm of chromosome 8 resulting from a t(8p+;11q–) translocation (Ladda et al., 1974), has been restudied using high-resolution trypsin-Giemsa banding of prometaphase chromosomes. The results revealed a complex rearrangement with four break points in 8p, 11p, and 11q, leading to a net loss of an interstitial segment of 11p (region pl407→pl304) but not of 8p. His red blood cells contained normal activities of glutathione reductase (gene on 8p) and lactate dehydrogenase A (gene on 11p12), indicating a gene dosage consistent with the chromosomal findings. The revised interpretation of this case agrees with seven others reported as having aniridia and interstitial lip deletions in establishing the distal half of band 11p13 as the site of gene(s) which lead to aniridia and predispose to Wilms’ tumor if present in a hemizygous state. Possible relationships between heterozygous deletion of specific chromosomal bands llpl3 and 13ql4 and the autosomal dominant disorders aniridia, Wilms’ tumor, and retinoblastoma, respectively, are discussed.
Structural organization of chromosomes of the Indian muntjac (Muntiacus muntjak)
Authors: Ved Brat S. , Verma R.S. , Dosik H.
Published: May 2008

The identification, morphology, and banding pattern of the chromosomes of the Indian muntjac (Muntiacus muntjak) are described. A diagrammatic representation of the banding pattern as revealed by various techniques is presented following the nomenclature suggested by Paris Conference (1971) for human chromosomes. The Y2 chromosome and the neck of the X chromosome are late replicating based on observations made with the use of a bromodeoxyuridine plus Giemsa technique. Most of the G-bands are early replicating, contrary to earlier findings based on autoradiography.
Conservation of whole arms during chromosomal divergence of phyllotine rodents
Authors: Walker L.I. , Spotorno A.E. , Fernández-Donoso R.
Published: May 2008

The assumption of simple fusion in a group showing a constant number of chromosome arms was tested by comparison of the G-band patterns of chromosomes of three Phyllotis species. The karyotypes, each of which has 40 chromosome arms, have a 2n of 38, 38, and 40 and are made up of mostly metacentric chromosomes. Operational concepts describing the amount of matching in G-band patterns are proposed, separating chromosomes or arms into those with total correspondence, partial correspondence, or unique cases. Seven chromosomes and 21 arms out of the total were identical in the three species, denoting a conservation of whole-arm band sequences in this group. A greater number of identical arms than of identical chromosomes was observed, giving some support to the simple fusion hypothesis. An unexpected chromosomal divergence was detected, including chromosomal variation in the C-banded sex chromosomes.
Cytogenetic characteristics of 26 polyethylene glycol-induced human-hamster hybrid cell lines
Authors: Wang H.S. , Niewczas V. , de S. Nazareth H.R. , Hamerton J.L.
Published: May 2008

A cytological analysis of 26 polyethylene glycol (PEG) induced human/hamster hybrid lines has shown that such lines are similar to inactivated Sendai virus (ISV) induced hybrids in respect to stability, retention of specific chromosomes, and cell selection. The evolution of stable hybrid cell lines carrying variable human chromosome complements depends upon a balance being established between the retained human and hamster genomes. This balance is a result of random loss of human and hamster chromosomes followed by selection of the fittest stem lines. A major mechanism of chromosome loss may be fragmentation and elimination of acentric fragments. Twelve of the 26 lines had stabilized by the 30th passage, an incidence similar to that found with ISV-induced hybrids studied in this laboratory. Thus, PEG may be considered to be an ideal chemical for inducing somatic cell hybrids for genetic analysis.
Inheritance of Ag-stainability of the nucleolus organizer regions in domestic sheep, Ovis aries
Authors: Henderson L.M. , Bruère A.N.
Published: May 2008

One of the nucleolus organizer regions of sheep is located on chromosome 25, which forms one arm of a Robertsonian translocation chromosome (t3). By mating sheep heterozygous and homozygous for the t3 chromosome, and with various Ag-staining frequencies and deposit sizes, the heritability of the Ag-stainability could be determined. The inheritance of Ag-stainability was studied in 54 sheep in five pedigree groups. It was shown that the Ag-staining of a NOR is a heritable property. Matings of animals heterozygous for Ag-stainability provided an estimate of recombination frequency of the short arm of t3.
Chromosome damaging agent of low molecular weight in the serum of New Zealand black mice
Authors: Emerit I. , Levy A. , de Vaux Saint Cyr C.
Published: May 2008

Two substrains of NZB mice were developed by selective matings according to chromosome breakage frequencies in direct bone marrow preparations: HB, a line with increased chromosome breakage, and LB, a line with low or normal breakage rates. The serum of NZB mice from the HB strain contains a chromosome breaking factor that produces chromosome abnormalities in human lymphocytes. This clastogenic substance could not be detected in serum of NZB mice from the LB line. Nor does it exist in serum of Balb, C3H, C57 B1, Swiss, or AKR mice, in which no chromosomal breakage was observed in bone marrow. The breakage factor has a molecular weight between 1000 and 10,000 daltons.
The use of translocation-derived “marker-bivalents” for studying the origin of meiotic instability in female mice
Authors: de Boer P. , van der Hoeven F.A.
Published: May 2008

Female mice of two age groups, 3–4 and 11–14 months old, homozygous for the T(1;13)70H reciprocal mouse translocation were used for cytological observations of bivalents (in primary oocytes) and metaphase II chromosomes (in secondary oocytes). Special attention was given to the behavior of the long (131) and short (113) marker chromosomes. In primary oocytes, univalents were considered “true” or “opposite.” The aged females showed an eight-fold increase in “true” univalent frequency for chromosome 113 over the young ones. A nine-fold rise for nondisjunction with regard to this chromosome was observed. For the other chromosomes, these factors were 2 and 1.7, respectively. The absolute levels of nondisjunction remained low at old age (1.42% for chromosome 113, 1.22% for all other chromosomes). The long marker bivalent 131 was used for chiasma counts. No change in chiasma number with age was observed. It is argued that poorer physiological conditions within the maturing oocytes of older females are the major cause for both the increasing frequencies of “true” and “opposite” univalents and the increased incidence of nondisjunction.
Integration site(s) of herpes simplex virus type 1 thymidine kinase gene and regional assignment of the gene for aminoacylase-1 in human chromosomes
Authors: Kit S. , Hazen M. , Qavi H. , Dubbs D.R. , Pathak S.
Published: May 2008

To investigate the chromosomal sites of integration of the herpes simplex virus type 1 (HSV-1) thymidine kinase (TK) gene in HSV-1-transformed human HeLa(BU25)/ KOS 8–1 cells, the biochemically transformed cells were fused with TK-negative mouse LM(TK-) cells, and human-mouse somatic cell hybrid lines (LH81) were isolated using a HATG-ouabain selection system. The presence of HSV-1 TK activity in the hybrid lines was verified by disc polyacrylamide gel electrophoresis (PAGE) and by enzyme neutralization with type-specific rabbit anti-HSV-1 TK immunoglobulin. Karyotype analyses of several somatic cell hybrid clones using G-banding, Hoechst 33258 staining, and combined G-banding and Hoechst staining demonstrated that they retained only a few human chromosomes. A marker chromosome, M7, consisting of a chromosome 17 translocated to the short arm of 3, occurred in 25 of the 28 metaphases examined. Also, chromosomes 8 and X were found in a minority of metaphases. Isozyme analyses showed that all 19 hybrid clones analyzed expressed human aminoacylase-1 (ACYl) and esterase D (ESD), markers for 3 and 13, respectively. Back-selection of somatic cell hybrid clones with 5-bromodeoxyuridine resulted in the isolation of several subclones lacking HSV-1 TK activity, human ACYl, human ESD, and the human chromosomes. These experiments suggest that the HSV-1 TKgene is associated with either M7 or a segment of 13, or both, in biochemically transformed HeLa(BU25)/KOS 8–1 cells. These experiments also permit localization of the ACYl structural gene to the pter→p12 region of 3.
Meiotic chromosomes of antelope squirrels
Authors: Mascarello J.T.
Published: May 2008

Cytological preparations of testes from squirrels belonging to the genus Ammospermophilus exhibit meiotic peculiarities specifically associated with constitutive heterochromatin.
Inhibition of mitochondrial-specific protein synthesis in human lymphocytes and platelets is dependent upon the stage of cellular differentiation
Authors: McGill M.
Published: May 2008

Small lymphocytes differentiate into functionally active blast cells in vitro upon stimulation with such mitogens as phytohemagglutinin and sodium periodate. If stimulated lymphocytes are subsequently treated with the nucleic acid intercalating dye ethidium bromide, electron-dense complexes containing nucleic acid are formed in mitochondria, protein synthesis in mitochondria is inhibited, and lymphoblast division ceases. Formation of complexes and the development of morphologically abnormal mitochondria provide ultrastructural evidence of mitochondrial protein inhibition and serve as markers for mitogen-responsive lymphocytes. The formation of these abnormalities in all mitochondria of treated megakaryocytes and 22% of mitochondria in platelets indicates that platelets contain functional nucleic acid and that the induced structural changes may be occurring in a less-differentiated (i.e., younger) subpopulation of circulating platelets.
A characterization of mitochondrial and mycoplasmal DNAs associated with cloned HeLa thymidine kinase minus cells
Authors: Robberson D.L. , Gay M.L. , Wilkins C.E. , Hodnett J.L.
Published: May 2008

HeLa S3 cells were cloned, recloned, and then selected for growth in the presence of increasing concentrations of bromodeoxyuridine. Cultures of these cloned thymidine kinase minus (TK-) cells were found to harbor mycoplasma which sedimented with mitochondria in sucrose density step gradients. Examination of mitochondrial DNA (mitDNA) components by restriction enzyme analysis and electron microscopy revealed no gross alterations in size, sequence arrangements, or replicative forms compared with mitDNA of HeLa S3 cells. Restriction enzyme cleavage sites for BamHl (one site), PstI (two sites) and HpaI (three sites) were mapped on this genome relative to the three cleavage sites for each of EcoRI and HindIII, respectively. Analysis of topological complexity revealed similar frequencies of catenated mitDNA molecules in both cloned TK– (22.5 ± 1.5% of mass) and HeLa S3 cells (25.6 ± 1.5% of mass). Unicircular dimers comprise 6.7 ± 0.9% of the mitDNA mass in cloned TK– cells but were not detected in HeLa S3 mitDNA. Examination of the mycoplasmal contaminant of mitochondrial DNA after digestion with various restriction enzymes and agarose gel electrophoresis revealed that most of the DNA was distributed in discretely sized fragments in patterns that can probably be used to unambiguously identify and classify the organism.
Asynaptic behavior of X and Y chromosomes in the Virginia opossum and the southern pygmy mouse
Authors: Pathak S. , Elder F.F.B. , Maxwell B.L.
Published: May 2008

The meiotic behavior of silver-stained X and Y chromosomes of the Virginia opossum, Didelphis virginiana, and the southern pygmy mouse, Baiomys musculus, was studied by light microscopy. While the sex chromosomes of these two species differ in both size and morphology, their meiotic behavior is very similar. In both species, a typical sex vesicle is formed during pachytene, but unlike most other mammalian species thus far studied, a synaptonemal complex does not form between the X and Y chromosomes. During pachytene, variable modes of association of the ends of the sex chromosomes (both heterologous and autologous) are sometimes observed. During diplotene, diakinesis, and metaphase I, the X and Y rarely appear to be associated. In some pachytene nuclei of B. musculus, the single axis of the biarmed X chromosome folds back upon itself, and the telomeres form a close association. While synaptic pairing segments of the sex chromosomes of the Virginia opossum may be displaced by telomeric heterochromatin on the X, true pairing regions between the X and Y of the pygmy mouse may be lacking.
Observations in a case of an X/Y translocation, t(X;Y)(p22;q11), in a mother and son
Authors: Pfeiffer R.A. , Stehling D.
Published: May 2008

A t(X;Y)(p223;q11) was studied in a mother and son who share features of Turner’s syndrome (short stature, mild brachymesomelia, unusual dermatoglyphics) as well as mental deficiency. In the majority of the mother’s cells the extra chromosome is late replicating. Ten previous cases are summarized, and the significance of Xp deletions is discussed.
Variable positions of NORs in Mus musculus
Authors: Winking H. , Nielsen K. , Gropp A.
Published: May 2008

Silver-NOR staining has been applied to mouse (Mus musculus) chromosomes of different feral populations from Italy, Yougoslavia, and Germany and to chromosomes of M. spretus, a closely related species, from Portugal. In addition to the known pattern of proximal sites on smaller autosomes, terminal sites with silver-NORs on chromosomes 4 and 13 were detected. In M. spretus only terminal NORs were present on chromosomes 4, 13, and 19. Thus, the location of silver-NORs within the genus Mus and M. musculus subspecies shows wide variation
Chromosome bands and the subunit structure of Chinese hamster metaphase chromosomes
Authors: Stubblefield E.
Published: May 2008

Isolated Chinese hamster chromosomes dissociate into a series of specific chromatin subunits approximately the size of stainable chromosome bands upon reduction of the divalent ion concentration during or after isolation. At high pH the chromatin in some bands is differentially removable during chromosome isolation, leaving a banded chromosome with a pattern typical of most G-band procedures. This provides an alternate molecular mechanism to explain the production of banded chromosomes by a variety of staining procedures. These results also suggest an approach to chromatin fractionation, using metaphase chromosomes as a starting material.
Dinucleotide priming of RNA synthesis
Authors: Shaw P.A. , Marshall M.V. , Saunders G.F.
Published: May 2008

Initiation of RNA synthesis with preformed dinucleotides as primers and either a bacterial or a eukaryotic DNA-dependent RNA polymerase was used to probe sequences on DNA or chromatin that are available for transcription. Using saturating levels of Escherichia coli RNA polymerase or wheat germ RNA polymerase II to transcribe free DNA, a preference was noted for the dinucleotides GpA, GpG, ApG, and UpG for initiation of RNA synthesis. When saturating levels of E. coli RNA polymerase were used to transcribe chromatin, a little preference was noted for UpA and UpC; wheat germ RNA polymerase II, on the other hand, utilized the dinucleotides GpA, ApG, ApA, and UpG more efficiently. Under conditions of limiting amounts of enzyme to transcribe chromatin, wheat germ RNA polymerase preferred to initiate RNA synthesis with the dinucleotide primers GpA, ApA, ApC, and UpG; E. coli RNA polymerase preferred GpA and GpG. These results emphasize both the role of the configuration of the template and the role of the enzyme in sequence selection for initiation of transcription.
Differences between “spontaneous” and induced sister-chromatid exchanges with fixation time and their chromosome localization
Authors: Ockey C.H.
Published: May 2008

Mean “spontaneous” SCE values have been investigated in synchronized CHO and S3/4 fibroblasts and in phytostimulated human peripheral lymphocytes. Significant increases were found at progressive fixation times following BrdU introduction in all cultures. Similar increases were observed with fixation times in SCEs induced by pulse treatment with methyl methane sulphonate (MMS) at various stages in the S period in CHO cells. In the fibroblast cultures these increases ranged from 20 to 80% with an 8-h interval between fixations. The percentage increase depended on the real proliferation occurring during this fixation interval. In the lymphocyte cultures, fixation intervals ranging from 22 to 54 h yielded increases of 40 to 80%. It is proposed that when SCE yields are compared in the SCE test for potentially damaging agents, the stages in cell proliferation expressed as frequencies of first, second, and third mitoses after BrdU incorporation should be taken into account. The distribution of “spontaneous” and MMS-induced SCE’s have been examined in marker chromosomes of the CHO cells. Although “spontaneous” SCE’s are nonrandomly distributed, they do not appear to show a high incidence over any specific type of banded region. MMS-induced SCEs, on the other hand, are preferentially located over those chromosome sites in replication at the time of pulse treatment.
Phase response to heat shock as evidence for a timekeeping oscillator in synchronous animal cells
Authors: Klevecz R.R. , Kros J. , King G.A.
Published: May 2008

Synchronous animal cells given heat shocks at 0.5-h intervals through an 8.5-h cell cycle display a biphasic pattern of advances and delays in subsequent cell divisions. This phase-response curve to perturbation by heat shock has a period of approximately 4 h and cannot readily be explained by commonly used models of cell cycle traverse. We suggest that this outcome is the consequence of timekeeping by a macromolecular oscillator with limit cycle properties.
Nucleolar activity in differentiated cells after stimulation
Authors: Arrighi F.E. , Lau Y.-F. , Spallone A.
Published: May 2008

Initiation of nucleolar organizer region (NOR) activity was observed by using the silver staining method at various times after activation or stimulation of differentiated cells. Two methods were used: (1) activation of human lymphocytes by treatment with phytohemagglutinin (PHA), and (2) cell-cell fusion of chick erythrocytes with squirrel monkey cells. An increase in NOR activity in lymphocytes was seen as early as 4 h after PHA treatment and between 10 and 22 h in the chick erythrocytes after fusion. In both systems, as the size of the dormant cell nucleus increased, the amount of silver staining increased until the silver-stained area approached that of cycling cells.
Factors affecting the induction of chromosomal aberrations by cadmium in Chinese hamster cells
Authors: Deaven L.L. , Campbell E.W.
Published: May 2008

Chinese hamster cells (line CHO) were examined for cadmium-induced growth-rate perturbations and chromosomal aberrations. The threshold concentration of Cd++ for the induction of chromosomal aberrations in CHO cells cultured in F-10 medium supplemented with 15% newborn calf serum was determined to be 1 × 10–6 M. CHO cells grown in the presence of nontoxic levels of Cd+ + (2×10-7 m) for 12 wk became resistant to toxic levels (2 x 10–6 m) after this exposure. Metaphase cells in these resistant populations contained only background levels of chromosomal aberrations. CHO cells grown in medium supplemented with several types of serum (fetal calf, newborn calf, and human) at concentrations commonly used for in vitro culture (5–20% v/v) or found in mammalian circulatory systems (50% v/v) differed markedly in Cd+ + tolerance. Cells grown in medium containing 1 × 10–6 MCd++ and supplemented with human or newborn calf serum were slightly protected against Cd++ damage at high serum concentrations (30 and 50% v/v) and accumulated approximately 90 µg Cd++/109 cells in 48 h. Cells growing at low or high concentrations of fetal calf serum were completely protected from 1×10-6 m Cd++ and accumulated approximately 12 µg Cd/109 cells in 48 h. The threshold Cd++ concentration for euploid Chinese hamster cells derived from skin, lung, and kidney tissues was determined to be 2 x 10–δ m. Cadmium does not induce elevated sister chromatid exchange levels. These results demonstrate the necessity for standardized protocols for cytogenetic investigations of Cd++ toxicity and may help to explain the discrepancies between studies of chromosome damage in patients with high Cd++ blood levels.
The karyotype of the hexaploid species Xenopus ruwenzoriensis Fischberg and Kobel (Anura: Pipidae)
Authors: Tymowska J. , Fischberg M.
Published: May 2008

The chromosome number of the hexaploid species Xenopus ruwenzoriensis is 108. The chromosomes fall into sets of six usually similar chromosomes (hextets) which can be classified into the morphological groups characteristic for the genus Xenopus. However, the three distinct secondary constrictions, typical for X. ruwenzoriensis, appear on two homologs only within a particular hextet, unmasking an underlying heterogeneity. The secondary constrictions on chromosome pair 11 show chromosomal association and are considered to represent the nucleolar organizer regions. There is no evidence of dimorphic sex chromosomes. Plates of spermatocyte metaphase I generally show bivalents, but single large multivalents have also been observed. In the majority of cases, 54 dyads are found in second spermatocyte metaphases. X. ruwenzoriensis is, therefore, either an ancient auto-hexaploid or, more likely, an allopolyploid of more recent origin.
The use of high resolution banding in comparative cytogenetics: comparison between man and Lagothrix lagotricha (Cebidae)
Authors: Dutrillaux B. , Couturier J. , Fosse A.-M.
Published: May 2008

New techniques for obtaining high resolution banding are used in comparative cytogenetics. They make possible a direct comparison of the chromosomes of two distantly related primates, man and Lagothrix lagotricha (Platyrrhine). For many chromosomes, the homoeologies of banding are surprisingly clear. These new results strongly strengthen the interpretations proposed with the use of more conventional banding techniques.
Flow cytogenetics of uncloned and cloned Chinese hamster cells
Authors: Otto F.J. , Oldiges H. , Göhde W. , Barlogie B. , Schumann J.
Published: May 2008

Flow cytometry has greatly facilitated the routine use of DNA content as a cellular indicator of the stages of the cell cycle and ploidy. DNA content can also be used to distinguish individual chromosomes. Fluorescent staining of chromosome DNA was done with a combination of ethidium bromide and mithramycin in hypotonic solution. Subsequent detergent treatment of the cells with Triton X-100 facilitated chromosome isolation. DNA flow cytometry of chromosomes of four established uncloned Chinese hamster cell lines showed 10 to 12 major subpopulations of chromosomes with varying degrees of overlap in the range of low and intermediate DNA content. Cloning of B14F28 cells, the line with the largest heterogeneity in chromosome number and DNA content, considerably reduced the dispersion in chromosome number and improved the resolution of DNA content distributions. Thus, cloned cells with a relatively homogeneous karyotype permit better discrimination of chromosome subpopulations by DNA content than uncloned cells and provide a more sensitive system to study mutagenic effects.
Human chromosome 11 affects the expression of fibronectin fibers in human × mouse cell hybrids
Authors: Eun C.K. , Klinger H.P.
Published: May 2008

Synteny between fibronectin (FN) production and human chromosome 11 was established in cell hybrids of FN-producing embryonic diploid fibroblasts and non-producing heteroploid mouse A9 cells. Because the FN antiserum used reacts with both human and mouse FN, it is not clear if the human 11 carries structural or regulatory information for FN production or information that influences FN expression in some other way. In different human x mouse systems, Owerbach et al. (1978) found synteny between chromosome 8 and FN, and Smith et al. (1979) with 3 and 11. The latter authors suggest that chromosome 3 controls expression and that the 11 has the structural gene. The human 3 and 8 were eliminated as necessary for FN production in the hybrids of this study. Since different cell hybrids and FN assay methods were used in the three studies, and the species specificity of some of these assays has not been established, it is not clear if several structural FN loci, as well as regulatory or modifying factors, are involved. It will be interesting to clarify the mechanisms affecting the expression of this glycoprotein because it appears to play a role in differentiation, development, and possibly also in tumorigenicity.
Karyotypes, constitutive heterochromatin and taxonomy of ringtail opossums of the genus Pseudocheirus (Marsupialia: Petauridae)
Authors: Murray J.D. , Sharman G.B. , McKay G.M. , Calaby J.H.
Published: May 2008

Karyotypes are presented for three forms of the common ringtail opossum, Pseudocheirus peregrinus. These are tentatively regarded as the subspecies P.p. cookii, P.p. pulcher, and P.p. rubidus. In addition, we report for the first time the karyotype of the rock ringtail opossum, P. dahli. The three forms of P. peregrinus each have a diploid number of 2n = 20. C-banding studies indicate that the addition of large blocks of constitutive heterochromatin has played a major role in the evolution of all chromosomes in the karyotype. The X chromosome of P.p. pulcher is metacentric and approximately twice the relative size of the acrocentric X chromosomes of the other two forms of peregrinus. All three forms had two or three pairs of autosomes with secondary constrictions, a rare occurrence within the superfamily Phalangeroidea. P. (Pseudochirops) dahli has a diploid number of 2n = 16; a reduction in chromosome number may have occurred by Robertsonian fusions. Four of the eight chromosome pairs lack large blocks of C-band material and the secondary constrictions are located on the sex chromosomes.
Aging and sister chromatid exchange
Authors: Nakanishi Y. , Dein R.A. , Schneider E.L.
Published: May 2008

Induction of sister chromatid exchanges (SCE) was examined as a function of post-embryonic development in C57BL/6J mice and Wistar rat bone marrow cells. At low concentrations of three different mutagens, cyclophosphamide, mitomycin C, and doxorubicin, induced SCE levels were not altered with post-embryonic development. However, at higher mutagen concentrations, SCE induction was significantly reduced in growing (3- to 8-week-old) animals when compared to mature (7- to 9-month-old) animals. Studies of 1- to 8-month-old mice at these high doses revealed that mutagen-induced SCE frequencies increase gradually during this period. These results suggest that with post-embryonic development, changes occur in cellular response to mutagen-induced DNA damage.
Tolerance of autosomal imbalance by the Syrian hamster (Mesocricetus auratus)
Authors: Savage J.R.K. , Breckon G. , Goy P. , Bigger T.R.L.
Published: May 2008

Cytogenetic and transmission data are given for a number of radiation-induced and spontaneous chromosomal changes which show that the Syrian hamster (Mesocricetus auratus) can tolerate a considerable amount of autosomal imbalance without phenotypic effect. It is suggested that the reason for this may lie in the very large amount of late-replicating chromatin present in this species.
Metaphase chromosome associations: Colcemid distorts the pattern
Authors: Rodman T.C. , Flehinger B.J. , Rohlf F.J.
Published: May 2008

The nonrandom pattern of the spatial arrangement of chromosomes in the human metaphase complement has been resolved into separate properties by statistical analysis of matrices of ranks of interchromosomal distances averaged over sets of 25 or 50 metaphases. Assessment of the effect of a mitotic-arresting agent, Colcemid, on each of the properties of the pattern shows that those properties for which a spindle fiber dependence may be postulated are disordered by Colcemid, while the tendency for the acrocentric chromosomes to associate, attributable to their mutual participation in nucleolar organization, is not impaired by Colcemid. Furthermore, this analysis has revealed that chromosomes 21 and 22 display an exceptional propensity to be generally associative, i.e., to be close to all chromosomes; that property is obliterated by Colcemid. Since a mitotic-arresting agent is routinely used in the preparation of cells for cytogenetic analysis, that property has hitherto not been recognized.
Ring chromosome 15: phenotype, Ag-NOR analysis, secondary aneuploidy, and associated chromosome instability
Authors: Ledbetter D.H. , Riccardi V.M. , Au W.W. , Wilson D.P. , Holmquist G.P.
Published: May 2008

Cytogenetic analysis of a 15 month old girl evaluated for severe developmental delay and acral skeletal hypoplasia revealed a predominant 46, XX, r(15) karyotype. Prophase banding analysis showed minimal deletion of the ring chromosome (breakpoints pl2 and q26), while silver staining showed it to have an active nucleolus organizing region, multiple abnormal secondary configurations, and decreased satellite association. Although there was no spontaneous instability in the rest of the karyotype, gentian violet-induced chromosome breakage was significantly increased. The rate of spontaneous sister chromatid exchange was not elevated. Cellular mosaicism for chromosome 15 aneuploidy most likely accounts for the patient’s phenotypic abnormalities.
A reciprocal translocation induced in an oocyte and affecting fertility in male mice
Authors: Beechey C.V. , Kirk M. , Searle A.G.
Published: May 2008

The reciprocal translocation T(5;12)31H, induced by irradiation of oocytes, causes sterility in most heterozygous male carriers, a tenfold reduction in mean sperm count, and a high frequency of abnormal sperm. Chromosome breakpoints are in bands 5B and 12F1, leading to a long (125) and a short (512) marker chromosome. Ninety five percent of germ cells showed chain quadrivalents or trivalents at meiotic metaphase I (MI). The order of loci on chromosome 5 is centromere—T31H—Rw—go with a recombination frequency of 31 + 7% between T31H and Rw. No linkage was found between T31H and linkage group XVI genes previously assigned to chromosome 12; it was concluded that they are located elsewhere. Viable tertiary monosomic and trisomic young (lacking the 512 region or with it in excess) were generated with post-natal frequencies of 4.5% and 14.6%, respectively, from outcrosses of heterozygous females. A deficiency of monosomics was also found in 11½ to 14½ day foetuses, when abnormal phenotypes or severe retardation produced by other unbalanced karyotypes were found. There was also a marked deficiency of monosomic offspring from outcrossed monosomic mothers, only 16.1% being found, whereas trisomic mothers gave 52.8% trisomic young. Surviving monosomics of both sexes were smaller than trisomics at birth and tended to have unusual skeletal fusions. Both types of aneuploid male were sterile, but tertiary monosomics were less severely affected, as judged by testis mass, sperm counts, and the appearance of testis sections. Both tertiary monosomic and trisomic females have smaller litters than normal females. Possible reasons for these findings are discussed, as well as recent observations throwing light on mechanisms of sterility in this type of translocation.
The interrelationship of chromosome banding patterns in the giant panda (Ailuropoda melanoleuca) hybrid bear (Ursus middendorfi × Thalarctos maritimus), and other carnivores
Authors: Wurster-Hill D.H. , Bush M.
Published: May 2008

The banded chromosomes of the giant panda (Ailuropoda melanoleuca) and a hybrid bear (Ursus middendorfi × Thalarctos maritimus) have been studied and compared to those of other carnivores. The giant panda shares only a few apparently homologous chromosome arms with the bear (Ursidae) and equally few with the lesser panda, Ailurus julgens (Procyonidae). Chromosomal evidence suggests appropriate placement of the giant panda in a family separate from the Ursidae and the Procyonidae.
A diffusable clastogenic factor in ataxia telangiectasia
Authors: Shaham M. , Becker Y. , Cohen M.M.
Published: May 2008

Cocultivation of plasma and lymphocytes from ataxia telangiectasia (AT) patients with those of normal individuals resulted in a significant increase in chromosomal damage in the normal cells. Tissue culture medium used to cultivate AT skin fibroblasts also significantly increased chromosome breakage in PHA-stimulated normal lymphocytes. This clastogenic effect was maximal when the “conditioned medium” was 8–9 days old. A similar effect was not observed with medium derived from normal skin fibroblasts. These observations suggest the presence of a clastogenic factor in the plasma of AT patients which may also be produced by AT skin fibroblasts in culture.
Assignment of the gene for human neutral alpha-glucosidase C to chromosome 15
Authors: Martiniuk F. , Hirschhorn R. , Smith M.
Published: May 2008

Human neutral α-glucosidase C (GANC) can be separated from the homologous mouse isozyme by starch gel electrophoresis at pH 6.5. A total of 40 clones (13 primary and 27 secondary) were derived from eight separate hybridization experiments between the mouse HPRT deficient RAG cell line and eight different human long term lymphoid cell lines or fetal cells. The thirteen primary clones showed 100% concordance between the expression of the human enzyme and the presence or absence of human chromosome 15. Analysis of the 27 secondary clones showed only two subclones discordant for segregation of human GANC and enzyme markers for 15. The two apparently discordant clones for human GANC were both derived from the same RAG × human fetal lung primary clone, and both lacked GANC activity, while retaining a 15. Since human GANC is polymorphic with a null allele at high frequency (Martiniuk and Hirschhorn, 1980), it is possible that these subclones carried one chromosome with a null allele for GANC. Alternatively there could been an undetected chromosome break between the GANC locus and the loci of the marker enzymes. Whatever the reason for the two apparently discordant subclones, combined data from all 40 clones show 95% concordant segregation for human GANC and No. 15.
Chromosomal mapping of human creatine kinase (brain type) using human-rodent somatic cell hybrids
Authors: Chern C.J. , Tan P. , Park H.
Published: May 2008

Concordant segregation of human brain-type creatine kinase, CK(BB), expression with nucleoside phosphorylase (NP) expression and the presence of chromosome 14 was observed in 53 independently derived cell hybrids between CK(BB)-positive human cells and CK(BB)-negative rodent cells. Further analysis of 26 subclones of two CK(BB)-positive human-mouse cell hybrids confirmed the positive correlation of CK(BB) expression with NP expression. The results suggest that the gene coding for human CK(BB) can be assigned to chromosome 14.
Patterns of replication of human chromosomes in human × mouse hybrids with different chromosomal compositions
Authors: Farber R.A.
Published: May 2008

The order of termination of DNA replication of ten human chromosomes remaining in a hybrid between normal human skin fibroblasts and mouse RAG cells has been analyzed. The human chromosomes were Nos. 2, 3, 4, 5, 6, 7, 10, 16, 17 and the Y. The order of replication of these chromosomes was essentially the same as that of the corresponding chromosomes in normal fibroblasts. This hybrid contained four human chromosomes, 6, 16, 17, and the Y, which were not present in a related hybrid (RRP5-4) which had been studied previously. Several chromosomes in RRP5-4, including 4, 5, and 7, had been shown to replicate at different times than the same chromosomes in the normal parental fibroblasts. These results suggest that there may be specific genes which are important for the control of the precise order of replication of human fibroblast chromosomes. These genes could be located on chromosomes which were retained in the hybrid analyzed here but which were missing from RRP5-4.
Growth kinetics of ataxia telangiectasia lymphoblastoid cells
Authors: Cohen M.M. , Simpson S.J.
Published: May 2008

Growth rates were investigated in long-term lymphoblastoid cell lines derived from normal individuals and patients with ataxia telangiectasia (AT R). By a cell doubling method, sister chromatid exchanges, and autoradiography, the AT R cells showed a significantly longer total generation time. Autoradiography demonstrated that the difference in cell cycle was due to a specific lengthening of the S period in the AT R lymphoblasts.
Banding patterns of the chromosomes of Miopithecus talapoin compared with Macaca mulatta and Cercopithecus aethiops
Authors: Ponsà M. , Estop A.M. , Miró R. , Rubio A. , Egozcue J.
Published: May 2008

The G-, C-, and Q-banding and NOR patterns of the chromosomes of Miopithecus talapoin are described. G-banding patterns are compared with those of Macaca mulatta and Cercopithecus aethiops which show large homoeologies.
Induction of chromosome aberrations, sister chromatid exchanges, and specific locus mutations in Chinese hamster ovary cells by 5-bromodeoxyuridine
Authors: San Sebastian J.R. , O’Neill J.P. , Hsie A.W.
Published: May 2008

The induction of cytotoxicity, growth inhibition, specific locus mutations, and cytological alterations such as micronuclei, chromosome/chromatid aberrations, and sister chromatid exchanges by 5-bromodeoxyuridine (BudR) in Chinese hamster ovary cells was determined. BudR shows concentration-dependent increases in cytological alterations over the range of 5–500 µM, but it is mutagenic only at concentrations greater than 50 µM.
A reassessment of the karyotype of Papio ursinus
Authors: Bernstein R. , Pinto M. , Morcom G. , Bielert C.
Published: May 2008

The Giemsa-banded karyotype of the chacma baboon, Papio ursinus, was shown to be identical to that of Papio hamadryas. Comparison of G-banded P. ursinus (PUR) chromosomes with those of man (HSA) showed close morphological homoeology between PUR and HSA chromosomes 5, 8, 12, 19, and X, and partial homology for seven other PUR and HSA chromosomes. PUR 10 showed a striking resemblance to HSA 15 and 22 and was the only Papio chromosome containing a nucleolar organizer region (NOR). This baboon chromosome, therefore, shows genetic homoeology with human acrocentrics for at least 18S and 28S rRNA gene loci. It is postulated that HSA 15 and 22 originated from the fission of a larger submetacentric chromosome in a lower primate.
Cytogenetic analysis of great horned owls (Bubo virginianus)
Authors: Biederman B.M. , Florence D. , Lin C.C.
Published: May 2008

A chromosome analysis of seven great horned owls (Bubo virginianus, Gmelin) has been performed on peripheral lymphocytes. The modal chromosome number was found to be 2n = 82. Measurements of relative lengths and arm ratios of the macrochromosomes were made. All chromosomes contain a region of constitutive heterochromatin in a centromeric location, with the W chromosome being composed almost entirely of this material. Chromosome replication, as demonstrated by the BudR-acridine orange method, showed synchronous replication of the two Z chromosomes of the male and late replication of the W chromosome of the female. In this species, functional regions of nucleolar organization appear to be localized to the microchromosomes.
Demonstration of a heritable fragile site in human chromosome 16 with distamycin A
Authors: Schmid M. , Klett C. , Niederhofer A.
Published: May 2008

Fragile sites are induced in chromosome 16 (band q22) of lymphocytes from some individuals, when the lymphocyte cultures are treated with the oligopeptide antibiotic distamycin A. These induced fragile sites are inherited in a Mendelian fashion; there are interfamilial differences in their appearance. The interactions between distamycin A and chromosomal DNA and the possible composition of the DNA at the induced fragile sites are discussed.
Mastomys (=Praomys) natalensis is not a Rattus (Mammalia: Rodentia): karyological evidence
Authors: Lee M.R. , Martin L.K.
Published: May 2008

Certain past studies have suggested that the taxa Mastomys (= Praomys) and Rattus were closely allied phyletically. We here present detailed (C- and G-banding and NOR’s) comparisons of the karyotypes of M. natalensis (2n = 36) and R. norvegicus (2n = 42). A standardized G-banded karyotype of M. natalensis is also presented. About 45% of the G-banded karyotype of M. natalensis is homologous with that of R. norvegicus. Autosomal constitutive heterochromatin is nearly equivalent in the two species; the X and Y chromosomes of M. natalensis, however, have exceptionally large heterochromatic segments. Both species possess three pairs of NOR’s, but adjacent G-banded regions are homologous for only one of these. Primarily on the basis of overall G-band homology, we regard the two taxa as only distantly related.
Assignment of a gene for succinate dehydrogenase to human chromosome 1 by somatic cell hybridization
Authors: Mascarello J.T. , Soderberg K. , Scheffler I.E.
Published: May 2008

A Chinese hamster cell mutant has been described with little or no activity of succinate dehydrogenase (Soderberg et al., 1977). We describe here the selection and characterization of human-hamster hybrids obtained from the fusion of these mutant cells and human lymphoblasts or HT1080 fibrosarcoma cells. The presence of human chromosome 1, identified by cytogenetic techniques and isozyme analysis, is correlated with the restoration of succinate dehydrogenase activity in the hybrids, and segregants are described in which the loss of all or part of human chromosome 1 has also led to a loss of this activity. We present results which support the claim that the mutation in the Chinese hamster cells is in one of the two structural genes for the 70,000 and 30,000 dalton peptides, respectively, which constitute succinate dehydrogenase. One of these two genes is therefore mapped on human chromosome 1.
Linkage studies on glyoxalase I (GLO), pepsinogen (PG), spinocerebellar ataxia (SCA1), and HLA
Authors: Whittington J.E. , Keats B.J.B. , Jackson J.F. , Currier R.D. , Terasaki P.I.
Published: May 2008

Pedigree analyses of five families in which a form of spinocerebellar ataxia (SCA1) is present have been used to obtain additional information on the location of SCA1 on chromosome 6. Recombination rates with HLA and glyoxalase I (GLO) suggest that the order is HLA-GLO-SCA1. There was no evidence for linkage of pepsinogen isozyme-5 (PG) either to HLA or GLO.
Regional localization of the genes coding for human ACO2, ARSA, and NAGA on chromosome 22
Authors: Geurts van Kessel A.H.M. , Westerveld A. , de Groot P.G. , Meera Khan P. , Hagemeijer A.
Published: May 2008

The segregation of the chromosome 22 markers AC02, ARSA, and NAGA was studied in somatic cell hybrid clones. These hybrids were isolated following fusion of Chinese hamster (E36 or a3) cells with leucocytes of donors carrying an (X;22) or (1;22) translocation. The results suggest the assignment of ARSA and NAGA to the region 22q13→22qter and of AC02 to the region 22q11→22q13.
Characterization of ouabain resistant, hypoxanthine phosphoribosyl transferase deficient human cells and their usefulness as a general method for the production of human cell hybrids
Authors: Weissman B. , Stanbridge E.J.
Published: May 2008

Ouabain resistant mutants of hypoxanthine phosphoribosyl transferase deficient HeLa cells and euploid human fibroblasts were isolated and extensively characterized. These double mutants were used to test the prediction that they would be “universal hybridizers” for intraspecific human cell hybrid production. Hybrids were selected from fusions with human cells of diverse somatic origin. In addition it was shown that multi-parental hybrids can be generated using a modification of the selection system, a result which will be useful for gene dosage experiments involving human cells.
An experimental approach to the analysis of mechanisms of meiotic nondisjunction and anaphase lagging in primary oocytes
Authors: Sugawara S. , Mikamo K.
Published: May 2008

The in vivo genomic mutagenicity of colchicine in Chinese hamster primary oocytes was analyzed at a carefully chosen dose that did not completely arrest the formation of the first meiotic spindle but exhibited a remarkable ability to induce nondisjunction, very possibly as a result of inhibition of tubulin polymerization. A single dose of 3 µg of colchicine per gram body weight was administered intraperitoneally at the onset of formation of the first meiotic spindle in females with a normal estrous cycle. Morphologically abnormal secondary oocytes with one or two extremely large first polar bodies occurred frequently, namely, in 47 (11.3%) of 416 oocytes. Chromosome analysis of a total of 2,124 secondary oocytes revealed that the overall incidence of aneuploids increased significantly (P < 0.001) in the experimental group (25.9%, or 99/382) as compared with the control group (2.0%, or 35/1,742). The minimum genomic mutagenicity of colchicine caused non-disjunction in one or two bivalents and eventually induced the formation of aneuploid secondary oocytes with chromosome numbers within the haploid range. The maximum genomic mutagenicity at the selected dose caused the elimination of a large number of chromosomes from the egg body, in association with the formation of a giant polar body or bodies. Three types, each with two subdivisions, of abnormal chromosome segregation between the oocytes and their giant polar body or bodies were studied, revealing part of the process resulting in aneuploid production due to either nondisjunction or anaphase lagging. The fate of the lagging chromosomes was also observed; they were included in neither the oocytes nor the polar body but eventually degenerated within the perivitelline space. The conditions of the spindle in oocytes aged by pre- and postovulatory over-ripeness, both of which have been known to induce meiotic chromosomal nondisjunction, are discussed in relation to tubulin polymerization.
The bovine genes for phosphoglycerate kinase, glucose-6-phosphate dehydrogenase, alpha-galactosidase, and hypoxanthine phosphoribosyltransferase are linked to the X chromosome in cattle-mouse cell hybrids
Authors: Shimizu N. , Shimizu Y. , Kondo I. , Woods C. , Wegner T.
Published: May 2008

Bovine embryonic trachea cells were hybridized with mouse A9 cells deficient in hypoxanthine phosphoribosyltransferase, and cattle-mouse hybrid cell clones were isolated after HAT/ouabain selection. In these interspecific cell hybrids, bovine glucose-6-phosphate dehydrogenase, α-galactosidase, and phosphoglycerate kinase were expressed concordantly with bovine HPRT. Their expression depended on the presence of the bovine X chromosome. These data indicate that the genes for G6PD, PGK, and HPRT are linked and can be assigned to the bovine X chromosome.