bluuebunny/crossref_metadata_2025 huggingface dataset:
Confirmed assignments of 15 structural gene loci to chromosomes of four owl monkey karyotypes
Authors: Ma N.S.F.
Published: May 2008

Fifteen gene loci for constitutive enzymes previously localized to specific owl monkey chromosomes of karyotypes III, V, and VI are confirmed by their assignments to homologous chromosomes of owl monkey karyotypes I, II, IV, and VII. The syntenic mapping of LDHA and GPI on a large metacentric, II–2, and the separate assignment of these two loci to two acrocentrics, I–9 and I–15, provide genetic evidence supporting the proposed fusion-fission event that characterized the karyotypic difference between owl monkeys inhabiting Colombia and the Panama Canal Zone. Moreover, the proposed hypothesis on chromosome polymorphism among the Colombian owl monkeys with karyotypes II, III, and IV, resulting from a fusion-fission event involving one metacentric and two subtelocentric pairs, is supported by the assignment of LDHB and MDH1 to the large metacentric I–2 and the separate localization of these two gene loci to II–13 and II–14, respectively.
Chromosome polymorphism involving heterochromatic blocks in Chinese hamster chromosome 9
Authors: Ray F.A. , Bartholdi M.F. , Kraemer P.M. , Cram L.S.
Published: May 2008

A chromosome polymorphism was detected between two early passage euploid Chinese hamster cell strains when a fluorescence shift of the small metacentric No. 9 chromosome was resolved by flow cytometry. The characteristics of the polymorphism were studied using cultures established from ear clippings taken from 16 additional hamsters from our breeding colony. Additional variants of chromosome 9 were detected using flow cytometry, and a subset of these variants were analyzed by G- and C-banding. An increase of fluorescence recorded by flow cytometry correlated with an increase of centromeric heterochromatin. Autosomal normalization of the flow karyotype from 18 different animals indicated three distinct peak positions for chromosome 9. The results indicate that a discrete block of constitutive heterochromatin may be present in one or two extra copies within the small inbred colony of hamsters studied. To determine the inheritance patterns, hamsters with known polymorphic No. 9 chromosomes were bred. The flow karyotypes derived from the offspring of these matings provide strong evidence that chromosomal polymorphisms are inherited in Mendelian fashion.
Nondisjunction frequencies in Robertsonian heterozygotes from natural populations of the common shrew, Sorex araneus L.
Authors: Searle J.B.
Published: May 2008

Pregnant female common shrews were collected from an area of Robertsonian polymorphism, involving five different arm combinations, around Oxford (England). The females and their fetuses were karyotyped, and the karyotypes of the sires were deduced. Ten pregnancies where at least one parent was known to be either a single or double Robertsonian heterozygote were available for analysis. From these pregnancies, upper and lower estimates of anaphase I nondisjunction arising from Robertsonian heterozygosity were calculated to be 1.0–2.5% per heterozygous arm combination and 1.5–3.7% per heterozygous parent. One trisomic fetus with retarded development was identified. This trisomy can be attributed to anaphase I nondisjunction of a trivalent in a female Robertsonian heterozygote.
Comparative chromosomal mapping of the owl monkey serum albumin gene
Authors: Ma N.S.F. , Kurnit D.M.
Published: May 2008

We have mapped the albumin locus (ALB) in the owl monkey, Aotus trivirgatus, using a cloned human albumin gene probe, pcHSA 33-1. Rodent-owl monkey somatic cell hybrids were used to map the owl monkey albumin locus in three subgroups of Aotus, karyotypes II, V, and VI. Segregation analysis of the molecular hybridization pattern of pcHSA 33-1 in the somatic cell hybrids indicated that the albumin locus maps to chromosome 9 of owl monkey karyotype II, chromosome 12 of karyotype V, and chromosome 1 of karyotype VI. This assignment provides evidence for the homology of these three chromosomes and supports the hypothesis of Ma on the formation of chromosome 1 in karyotype VI.
3-Aminobenzamide-induced sister chromatid exchanges are dependent on incorporated bromodeoxyuridine in DNA
Authors: Zwanenburg T.S.B. , Natarajan A.T.
Published: May 2008

Data are presented establishing a direct correlation between 3-aminobenzamide-induced sister chromatid exchange (SCE) frequency and the level of bromodeoxyuridine (BrdU) incorporated into DNA. In addition, it is shown that most of the SCEs are induced in the second cell cycle, in which BrdU-containing DNA is used as the template for replication.
Evolution of chromosomal variation in cottontails, genus Sylvilagus (Mammalia: Lagomorpha)
Authors: Robinson T.J. , Elder F.F.B. , Chapman J.A.
Published: May 2008

Chromosomes from cultured fibroblasts of four cottontail species (Sylvilagus audubonii, 2n = 42; S. idahoensis, 2n = 44; S. nuttallii, 2n = 42; and S. palustris, 2n = 38) were analyzed using G- and C-banding techniques. The evolutionary restructuring of the genomes of these species was traced by comparing their banded chromosomes to those of Lepus saxatilis, a species of hare in which the leporid ancestral karyotype is thought to have been conserved. Chromosomal evolution appears to have proceeded primarily through changes in the amount and distribution of heterochromatin and through fixation of Robertsonian fusions. Excluding heterochromatic differences, S. audubonii and S. nuttallii are karyotypically very similar, as are S. aquaticus and S. palustris (previously reported). The genome of the taxonomically controversial species S. idahoensis, compared to other cottontail species, is markedly impoverished in C-band material. These data and those of cottontail species previously described in the literature are incorporated in two alternative phylogenetic schemes.
An extra segment in chromosome 1 of wild Mus musculus: a C-band positive homogeneously staining region
Authors: Traut W. , Winking H. , Adolph S.
Published: May 2008

An extra segment in chromosome 1 between bands C5 and D has been found in wild mouse populations. Its size varies between 6.1 % and 30.1 % of the length of a standard chromosome 1. It differs among individuals and populations but is constant in a genetically homogeneous line. According to its staining properties and variation in length it is a homogeneously staining region (HSR), a kind of segment otherwise found only in cell lines under strong selection and in tumor cells. G-banding gives a homogeneous staining of medium intensity. With C-banding, staining is positive, though lighter than that of centromeric heterochromatin. Fluorescence is dull with Hoechst 33258 and bright with mithramycin. The extra segment does not contain mouse satellite DNA sequences in any quantity detectable by in situ hybridization. Such an extra segment was found in several European populations of mice from Spain to Russia. It is carried through the germ line. It has been introduced into a laboratory mouse strain, and, by recombination, inserted into a Robertsonian metacentric chromosome for easier handling and identification.
Homozygosity for a Robertsonian translocation (13q14q) in three offspring of heterozygous parents
Authors: Martinez-Castro P. , Ramos M.C. , Rey J.A. , Benitez J. , Cascos Sanchez
Published: May 2008

A family containing three homozygous carriers for a Robertsonian (13q14q) translocation, 44, XX or XY, t(13q14q), t(13q14q), is reported. Their parents are first cousins, and both are heterozygous carriers of the same (13q14q) translocation. The fertility of both the heterozygous and homozygous carriers is discussed.
Meiotic association between the XY chromosomes and unpaired autosomal elements as a cause of human male sterility
Authors: Rosenmann A. , Wahrman J. , Richler C. , Voss R. , Persitz A. , Goldman B.
Published: May 2008

Intimate association between autosomal translocation trivalents and XY bivalents at pachytene was observed in a majority of cells of two men ascertained through primary sterility and found to be heterozygous for a 14;21 Robertsonian translocation. The association, studied by light and electron microscopy of spread first spermatocytes, was between the unpaired short arms of the normal chromosomes of the translocation trivalent and the differential axes of the XY chromosomes. In a minority of cells, this contact was not established, or not maintained, as alternative combinations between the elements available for non-homologous pairing were realized. Following a suggestion of Lifschytz and Lindsley (1972), sterility in these patients was attributed to spermatogenic arrest caused by physical contact of sex chromosomes with autosomal material and consequent interference with the normal metabolism of the sex chromosomes. Autosomal aberrations and polymorphisms, which lead to the presence of unpaired segments at meiosis, may thus play a critical role in a general mechanism of chromosomally-derived male sterility. It is proposed that such a mechanism may also be instrumental in the initiation of reproductive barriers in nature.
Comparative chromosome analysis of nine squamous cell carcinoma lines from tumors of the head and neck
Authors: Hauser-Urfer I.H. , Stauffer J.
Published: May 2008

The chromosomes of nine cell lines from human squamous cell carcinomas of the head and neck were examined. Five of the lines were derived from patients who had received chemotherapy and radiotherapy, one line was derived from a lymph-node metastasis from one of these patients, and three lines were from patients who had not been treated. The cell lines from the untreated patients had lower modal chromosome numbers than those of all but one of the lines from the treated patients. A structural abnormality involving chromosome 1 with breakpoints located in p13, p22, q21, or q32 was found in all cases. The NRAS and SK oncogenes are located in or near some of these segments. In four of the cell lines the nucleolus organizer regions (NORs) were 10–30 times larger than the NORs of the normal human chromosomes. Double minutes (DM) and homogeneously staining regions (HSR) were found in four of the lines.
The Chinese hamster Don cell line differs from normal diploidy by one chromosome band
Authors: Chen T.R.
Published: May 2008

G-banded and C-banded prometaphase and metaphase karyotypes of the Chinese hamster Don cell line from three different laboratories were compared. All the cell lines were pseudodiploid. Each consisted of two distinct cell populations designated S1 and S2. The chromosome complements of each of these populations differed from the diploid by only one additional chromosome band on a subterminal 1p in S1 and on a median 1q in S2. The sites of these extra bands were neither constricted nor heterochromatic. All other different karyotypes, including those from seven distinct subpopulations, had basic patterns of chromosome complements that were best represented by S1 or S2, respectively the major or minor cell type of the cell line. Moreover, nearly 80% of the metaphases analyzed had a modal chromosome number of 22, and about 60% had the same chromosome composition of a cell type or subtype. Our data also suggest that Don cells were probably pseudodiploid by 1964 or before.
Bilateral nephroblastoma associated with a 3;17 translocation
Authors: Soulie J. , Rousseau-Merck M.-F. , Mouly H. , Nezelof C.
Published: May 2008

Cultured cells from the tumor of a child with bilateral nephroblastoma were studied cytogenetically. All mitoses observed showed the same male karyotype, 46, XY, t(3;17). This translocation constitutes a newly discovered rearrangement that has not been reported previously either in nephroblastoma or in other neoplastic processes.
Assignment of the human antithrombin III structural gene to chromosome 1q23–25
Authors: Bock S.C. , Harris J.F. , Balazs I. , Trent J.M.
Published: May 2008

The human antithrombin III (ATIII) structural gene was mapped by in situ hybridization and quantitative analysis of ATIII gene dosage in DNA isolated from carriers of chromosome 1 deletions. These studies indicate that the ATIII structural gene maps to human chromosome 1q23–q25 and so is likely identical to AT3.
Induction of chromosome banding by trypsin/EDTA for gene mapping by in situ hybridization
Authors: Popescu N.C. , Amsbaugh S.C. , Swan D.C. , DiPaolo J.A.
Published: May 2008

We describe an easy and reproducible procedure that utilizes trypsin/EDTA for the induction of chromosome banding in conjunction with in situ hybridization. The high quality banding resolution required for grain localization is obtained on both elongated and contracted chromosomes derived from synchronized or nonsynchronized human lymphocytes or fibroblasts. This procedure can also be useful for gene localization on chromosomes from cancer cells.
The G-banded chromosomes of Roosevelt’s muntjac, Muntiacus rooseveltorum
Authors: Wurster-Hill D.H. , Seidel B.
Published: May 2008

The chromosomes of a female Roosevelt’s muntjac (Muntiacus rooseveltorum) captured in Laos have been studied with G-banding. The diploid number is six and the karyotype is indistinguishable from that of the Indian muntjac (Muntiacus muntjak vaginalis).
A viable calf with trisomy 22
Authors: Mayr B. , Krutzler H. , Auer H. , Schleger W. , Sasshofer K. , Glawischnig E.
Published: May 2008

Karyotyping of eight malformed calves resulted in the detection of trisomy 22 in one calf. This calf had a hernia umbilicalis, a urachus fistula, and slight brachygnathia inferior. This trisomy was not associated with lethality.
Synaptonemal complex analysis of a pericentric inversion in chromosome 2 of domestic fowl, Gallus domesticus
Authors: Kaelbling M. , Fechheimer N.S.
Published: May 2008

Electron microscopy of synaptonemal complexes in three Gallus domesticus cockerels that were heterokaryotypic for a pericentric inversion in chromosome 2 revealed a low incidence of homologous pairing and a high incidence of nonhomologous pairing. The significance of these results are related to the finding that heterokaryotypic parents have fertility rates that are normal or above normal and produce only balanced gametes. One cockerel apparently had both normal cells and cells with a heteromorphic bivalent 2 in its germ line.
Localization of glucose-6-phosphate dehydrogenase in mouse and man by in situ hybridization: evidence for a single locus and transposition of homologous X-linked genes
Authors: Martin-DeLeon P.A. , Wolf S.F. , Persico G. , Toniolo D. , Martini G. , Migeon B.R.
Published: May 2008

By hybridizing a tritiated human genomic probe (pGD3) to metaphase chromosomes in situ, we have localized the gene for glucose-6-phosphate dehydrogenase (G6PD) in both the human and mouse complement. The locus on the intact human X chromosome is close to the telomere on the long arm, confirming the assignment based on studies of an X/autosome translocation in human-mouse hybrids. Although the signal:background ratio was reduced for the heterologous hybridization of the human probe to mouse metaphases, 20% of the grains were on the X chromosome and 93% of these were in the A region, relatively close to the centromere. The location of G6PD in mouse and man reflects intrachromosomal transposition of these homologous X loci. Genomic DNAs from mouse and man and from hybrids with human X/autosome translocations were digested with several restriction enzymes including EcoRl, PstI, and HpaII, and Southern blots were probed with 32P-pGD3. The results of the analysis also confirm the human G6PD assignment and are consistent with a single copy of the locus in the haploid genome of both species.
Cytogenetic demonstration of out-of-phase DNA synthesis in endoreduplicated CHO cells: evidence for partial endoreduplication
Authors: Takanari H. , Nakakuki K. , Izutsu K.
Published: May 2008

Out-of-phase DNA synthesis, which is demonstrated cytogenetically as premature chromosome condensation (PCC), was analyzed in endoreduplicated Chinese hamster ovary (CHO) cells induced by colchicine or vincristine. Like conventional polyploid cells, endoreduplicated cells exhibited PCC in either S or G2. The former was more frequently observed in drug-treated cultures. In addition to these two types of PCC, other mitotic figures showing out-of-phase DNA synthesis were found. Such cells contained both conventional chromosomes (monochromosomes) and diplochromosomes. Differential FPG staining of chromatids in these cells showed that diplochromosomes incorporated BrdU twice while monochromosomes did so once, indicating the occurrence of partial endoreduplication in one of the sister nuclei of multinucleate cells. The possible mechanisms underlying induction of out-of-phase DNA synthesis and production of partial endoreduplication are discussed.
Human metallothionein-II processed gene is located in region p11→q21 of chromosome 4
Authors: Lieberman H.B. , Rabin M. , Barker P.E. , Ruddle F.H. , Varshney U. , Gedamu L.
Published: May 2008

Metallothionein (MT) genes comprise a multigene family encoding low-molecular-weight, heavy-metal-binding proteins. We have mapped a human MT-II processed gene to chromosome 4, using Southern blotting in combination with a human × mouse hybrid clone panel containing defined subsets of human chromosomes. We have further localized this gene to region p11→q21, using in situ hybridization.
Chromosomal site of hepatitis B virus (HBV) integration in a human hepatocellular carcinoma-derived cell line
Authors: Simon D. , Searls D.B. , Cao Y. , Sun K. , Knowles B.B.
Published: May 2008

The single site of integration of hepatitis B virus in the human hepatocellular carcinoma cell line Hep 3B 2-1/7 was found to segregate with human chromosome 12 in somatic cell hybrids. Analysis of metaphase spreads of Hep 3B 2-1/7 following in situ hybridization with pHBV revealed integration at 12q13→q14, a location that coincides with a fragile site, fra (12q13). The possible significance of this location to the development of hepatocellular carcinomas is discussed.
More precise localization of the human Factor IX gene by in situ hybridization
Authors: Quirk S. , Chou W.-G. , Polakowska R. , Zain S.B. , Young F.E. , Doherty R.A.
Published: May 2008

The location of the human antihemophilic Factor IX has been more specifically assigned from the region Xq27→qter to Xq26→q27 by quantitative in situ hybridization. The present study utilized a complex hybridization probe and prephotographed G-banded human chromosomes to improve analytical sensitivity and accuracy.
Quantitation of the transgenome size in chromosome-mediated gene transfer lines
Authors: Murphy P.D. , Miller C.L. , Ruddle F.H.
Published: May 2008

Twenty-two HPRT-selected chromosome-mediated gene transfer lines were characterized by quantitative “dot” blotting. The range of human sequences in these lines extended from over 120,000 kb to less than 5,000 kb. One-half of these lines carried less than 16,000 kb.
Characterization of G-banded chromosomes of the Indian muntjac and progression of banding patterns through different stages of condensation
Authors: Sen Pramila , Sharma T.
Published: May 2008

Muntjac prophase and metaphase chromosomes were G-banded following methotrexate-mediated synchronization of peripheral lymphocytes. Bands and subbands were characterized from prophase through metaphase, and the progression of band patterns from late prophase to mid-metaphase was analyzed. Extended prophase chromosomes exhibited more bands and subbands, a number of which became fused with each other, giving rise to fewer and thicker bands in the condensed metaphase chromosomes. It appeared that the dark bands condensed relatively more than the light bands. Precise delineation of the bands and subbands on extended prophase chromosomes and the usage of a proposed banding pattern nomenclature should aid in better detection and localization of induced chromosomal rearrangements with this extremely useful experimental material.
The thyroglobulin gene resides on chromosome 8 in man and on chromosome 7 in the rat
Authors: Brocas H. , Szpirer J. , Lebo R.V. , Levan G. , Szpirer C. , Cheung M.C. , Vassart G.
Published: May 2008

Human chromosomes were separated by a dual laser FACS sorter and their DNA hybridized with a thyroglobulin gene probe. A strong hybridization signal was obtained with DNA from chromosome 8. A panel of mouse-rat cell hybrids was used to determine the chromosomal localization of the rat thyroglobulin gene by the Southern blotting method. Comparison of the cytogenetic data with the hybridization signals obtained with the rat thyroglobulin probe allowed assignment of this gene to rat chromosome 7. It is concluded that the synteny relationship between the thyroglobulin gene and the c-myc oncogene has been conserved in rat and man.
Hybridization with human cells corrects the elevated SCE frequency and BrdU hypersensitivity of hamster cell line EM9
Authors: Ray J.H. , Louie E. , German J.
Published: May 2008

Cells of the Chinese hamster line EM9 exhibit an elevated SCE frequency and a decreased proliferative response in bromodeoxyuridine (BrdU)-containing medium. Here, these phenotypic features were examined experimentally using polyethylene glycol fusion of EM9 and normal human cells. EM9/human hybrids exhibited both normal SCE frequencies and normal proliferative responses in BrdU-containing medium, suggesting that SCE elevation and BrdU hypersensitivity in EM9 have a common molecular basis.
Preferential nondisjunction of specific bivalents in oocytes from Djungarian hamsters (Phodopus sungorus) following colchicine treatment
Authors: Hummler E. , Hansmann I.
Published: May 2008

In an attempt to study the mechanisms leading to nondisjunction during meiosis I, Djungarian hamster females were treated with colchicine (3 mg/kg), which binds specifically to tubulin. The number of ovulated oocytes per female was significantly reduced following colchicine treatment (8.2 + 5.3, compared to 10.6 + 5.9 in controls receiving saline solution only). Application of colchicine rather late during oocyte maturation (ie, 5.5 h after injection of human chorionic gonadotrophin) caused a significant increase in the number of ovulated diploid (34.5%) and hyperhaploid (11.7%) oocytes, compared to the frequencies observed in the saline-treated controls (0.8% and 3.5%, respectively). Specific bivalents (viz, the large meta- and submetacentric chromosomes of groups A, B, and C) were preferentially involved in colchicine-induced nondisjunction. The same pattern of chromosomal malsegregation was previously observed in oocytes from this hamster species following hypergonadotrophic stimulation. Preferential involvement of bivalents in the process of nondisjunction, whether induced by colchicine or hypergonadotrophic stimulation, is explained by an interference with microtubular function affecting those bivalents that are the last to segregate.
Breakage on chromosome 2 brings the Ck gene to a region 3’ of c-myc in a Burkitt’s lymphoma line carrying a (2;8) translocation
Authors: Malcolm S. , Davis M. , Rabbitts T.H.
Published: May 2008

We have shown using in situ hybridization that the constant region of the kappa light chain immunoglobuhn gene (Ck) is translocated from chromosome 2 to chromosome 8 in Burkitt’s lymphoma cells with a (2;8) translocation. The Ck gene then ends up adjacent to and on the 3’ side of c-myc. The breakpoint probably falls between the gene for the variable region of the kappa light chain (Vk) and the Ck gene.
In situ hybridization and translocation breakpoint mapping
Authors: Cannizzaro L.A. , Aronson M.M. , Emanuel B.S.
Published: May 2008

Using a combination of banding techniques, we examined two atypical 21;22 translocations, 46, XX or XY, t(21;22)(p11;q11). In situ chromosomal hybridization of a probe for the constant region of the lambda light chain locus demonstrated that the 22q11 breakpoints of both rearrangements were proximal to the Cλ gene cluster. These studies permitted us to distinguish the 22q11 breakpoints of these translocations from the breakpoint of the 22q — chromosome of chronic myelogenous leukemia.
In situ hybridization and translocation breakpoint mapping
Authors: Cannizzaro L.A. , Emanuel B.S.
Published: May 2008

We have performed in situ hybridization of a probe for the λ IGLC constant region to metaphase spreads from two DiGeorge syndrome (DGS)-related chromosomal rearrangements with breakpoints in 22q11. In this study we have demonstrated that the breakpoints are proximal to the λ IGLC constant region cluster. Thus, at the molecular level, DGS-related breakpoints can be distinguished from the 22q11 breakpoint of CML, but not from the 8;22 translocation of Burkitt lymphoma or from the 21;22 translocations that we have previously studied.
Detection of Y-specific repeat sequences in normal and variant human chromosomes using in situ hybridization with biotinylated probes
Authors: Lau Y.-F.
Published: May 2008

In situ hybridization with a cloned human Y-specific repeat, pY3.4, derived from the 3.4-kb HaeIII repetitive sequences, is useful in identifying Yq-autosome translocations. In this study nonradioactive procedures were also employed to detect the sites of hybridization. Using a biotinylated probe and either immunofluorescence or horseradish peroxidase reaction, the chromosomes of three probands and members of their families with probable Y-autosome translocations were examined. It was found that not all such translocations can be correctly diagnosed based on conventional banding analysis. The present data indicate the importance of chromosome-specific probes in studying chromosome rearrangements in man.
Studies on endoreduplication
Authors: Takanari H.
Published: May 2008

The metaphase appearance of quadruple chromosomes in colchicine-treated CHO cells was compared between air-dried and gently squashed preparations. A marked difference in morphology between the two methods suggested that the planar alignment of quadruple chromosomes is an artifact of the spreading process and that quadruple chromosomes are organized within the nucleus in a three-dimensional configuration. By analyzing the alignment of the original and replicated strands, using BrdU incorporation, the three-dimensional orientation of the chromatids in quadruple chromosomes could be traced. This analysis led to a new model for DNA replication. According to this model, an opening of a DNA base pair which rotates about 90° with respect to the deoxyribose phosphate backbone precedes DNA replication, resulting in the formation of the newly replicated strands perpendicular to the original plane of the base pair. This model, although derived from endoreduplication, may be applicable to a general scheme for DNA replication during normal chromosome duplication.
Assignment of uroporphyrinogen decarboxylase (UROD) to the pter→p21 region of human chromosome 1
Authors: McLellan T. , Pryor M.A. , Kushner J.P. , Eddy R.L , Shows T.B.
Published: May 2008

The assignment of the human gene for uroporphyrinogen decarboxylase (UROD) to chromosome 1 is confirmed and further localized to the pter→p21 region through the use of human-mouse somatic cell hybrids. Human and mouse UROD were separated by electrophoresis and identified with antibodies to the human enzyme after electrophoretic transfer to nitrocellulose membranes.
Effects of the male contraceptive agent gossypol on meiotic chromosomes of the male rat
Authors: Bhagirath T. , Kundu S.C.
Published: May 2008

Synaptonemal complexes (SCs) of rat spermatocytes were analyzed in silver-stained meiotic preparations 10–24 days after treatment with gossypol acetic acid, 30 mg/kg/day, for 70 days. Gossypol did not affect SC formation or function, as judged by the absence of pairing anomalies, SC fragmentation, or presynaptic arrest. The unpaired lateral axes could be seen at zygotene, and at pachytene normal SCs could be observed. The behavior of the XY axes also appeared to be normal.
Shiverer gene maps near the distal end of chromosome 18 in the house mouse
Authors: Sidman R.L. , Conover C.S. , Carson J.H.
Published: May 2008

Several mouse mutations cause unstable locomotion, tremor, seizures, and a reduced lifespan because of deficient myelin formation in the central nervous system. Mutant alleles at the shiverer (shi) locus are the only ones in this series with a selective molecular defect, namely, in myelin basic proteins (MBPs), which are virtually absent in shi homozygotes and 50% reduced in heterozygotes. In the present study, backcross and intercross matings indicate recombination of 21.2 ± 3.3% between myelin deficient, shimld, and fused phalanges, syfp, a marker near the middle of chromosome 18. Recombination of shimld with twirler (Tw), a marker near the centromere, is 45.7 ± 4.9%. Thus, the shi locus maps near the distal end of mouse chromosome 18 and is the first available marker for this region. Given the evidence of other workers that an MBP locus maps to the same mouse chromosome, and that part of this chromosome may be syntenic with an MBP-PEPA region on human chromosome 18, it is likely that shi is in or near an MBP gene.
Normal disjunction in Robertsonian heterozygotes from a highly polymorphic lizard population
Authors: Porter C.A. , Sites, Jr. J.W.
Published: May 2008

A single population of the iguanid lizard, Sceloporus grammicus, was found to have fission polymorphisms in three of four metacentric macrochromosome pairs. This variation resulted in eight different karyotypes in a sample of 24 lizards. Of these 24 lizards, 7 were single heterozygotes, 11 were double heterozygotes, and 1 was a triple heterozygote. Meiotic analyses of males heterozygous for different combinations of fissions indicated completely normal disjunction and production of chromosomally balanced gametes. The polymorphisms in this population did not appear to deviate strongly from Hardy-Weinberg equilibrium. There was no evidence of selection against chromosomal heterozygotes in this population.
Major chromosome homeologies between Muridae and Cricetidae
Authors: Viegas-Péquignot E. , Kasahara S. , Yassuda Y. , Dutrillaux B.
Published: May 2008

The presumed ancestral karyotype of Muridae, previously reconstructed, is compared with that of a selected Cricetidae species, Akodon a arviculoides. Most of the chromosomes of the presumed ancestral chromosomes of Muridae are homeologous to chromosome arms or segments in the Akodon karyotype. This result strengthens the validity of the reconstruction of the ancestral karyotype for both Muridae and Cricetidae.
Isolation and characterization of two repetitive DNA fragments located near the centromere of the mouse X chromosome
Authors: Disteche C.M. , Tantravahi U. , Gandy S. , Eisenhard M. , Adler D. , Kunkel L.M.
Published: May 2008

Two repetitive DNA fragments located on the mouse X chromosome are described. The fragments were isolated from a lambda phage library enriched in X-chromosomal sequences by flow sorting. Both fragments, which are repeated 20 to 50 times in the genome, were mapped to the mouse X chromosome by Southern blot hybridization to DNA from hybrid cells retaining the mouse X chromosome, by dosage analysis, and by in situ hybridization to mouse chromosomes. In mouse strain C57BL/10BK, one fragment appeared to be located only on the X chromosome, while the other fragment had homologous sequences on chromosome 11 in addition to the X chromosome. The latter fragment showed DNA variants between mouse strains, which are potentially useful for mapping. Both fragments cross-hybridized to another mouse species: Mus caroli. In this species, each fragment appeared to be located on the X chromosome, indicating that some X-chromosome repetitive sequences are partially conserved. In addition, one fragment cross-hybridized to human DNA.
Gene mapping in the Chinese hamster and conservation of syntenic groups and Q-band homologies between Chinese hamster and mouse chromosomes
Authors: Satoh H. , Yoshida M.C.
Published: May 2008

Using Chinese hamster/mouse somatic cell hybrids segregating hamster chromosomes, we assigned 15 enzyme genes to six different Chinese hamster autosomes. Of the 15 loci, three genes, HK1, PEPC, and SORD, were newly assigned to chromosomes 1, 5, and 6, respectively, while ENOl, PGD, and PGM1 were assigned to the long arm of chromosome 2, in the segment 2q113→qter. The locations of the following loci were confirmed: ESD, NP, and PEPB on chromosome 1, ME1 and MPI on chromosome 4, AK1 on chromosome 6, and GP1 and PEPD on chromosome 9. Comparative mapping of Chinese hamster and laboratory mouse chromosomes revealed conservation of syntenic groups and extensive banding homology between the Chinese hamster and mouse chromosomes on which homologous enzyme markers have been mapped.
Gene mapping in marsupials and monotremes
Authors: Dobrovic A. , Graves Marshall
Published: May 2008

Somatic cell hybrids have been obtained between HPRT Chinese hamster cells and cells from several dasyurid marsupial species. These hybrids show the extensive loss of marsupial chromosomes characteristic of the majority of marsupial-eutherian somatic cell hybrids. Although all of the hybrids expressed the selected marsupial marker, HPRT, the only other markers observed were PGK, GLA, and G6PD, consistent with the conservation of X-linked genes extending to this major group of marsupials. Counterselection confirmed the synteny of PGK and GLA with HPRT, whereas G6PD showed decreased concordance.
Determination of the DNA content of human chromosomes by flow cytometry
Authors: Harris P. , Boyd E. , Young B.D. , Ferguson-Smith M.A.
Published: May 2008

The mean relative DNA content of each human chromosome was calculated from flow karyotypes of ethidium bromide-stained chromosomes obtained from healthy, normal individuals. These values were found to correlate closely with previously published data obtained by photometric scanning of stained, fixed chromosomes. Calculations of the normal variation in DNA content of each human chromosome indicated that chromosomes 1,9, 16, and Y (chromosomes with large centric heterochromatic regions) were the most variable, followed by the acrocentrics, 13, 14, 15, 21, and 22. Chromosomes 2, 3, 18, and 19 were also found to vary significantly in DNA content. Chromosomes from a number of subjects with extreme heteromorphisms were flow karyotyped to obtain an estimate of the extent of variation in DNA content of each chromosome. The greatest difference between extreme variants was found for chromosome 1 (which differed by 0.82% of the total genomic DNA), followed by 16 and 9. The largest Y-chromosome variant was 85.9% bigger than the smallest. The precise karyotype analysis produced by flow cytometry resolved many differences between chromosome homologs, including some that cannot be readily distinguished cytogenetically. The implications of these findings for detection of chromosome abnormalities by flow karyotype analysis are discussed.
Site-specific chromosomal rearrangements induced in human diploid cells by x-irradiation
Authors: Kano Y. , Little J.B.
Published: May 2008

A total of 130 stable, two-break reciprocal translocations were scored in G-banded karyotypes prepared from 375 metaphase spreads from a strain of human diploid fibroblasts irradiated with 400 or 600 rads and analyzed 1–20 mean population doublings later. The chromosomal location of each of the 260 breakpoints was mapped. The sites of 121 chromosomal breaks and deletions in the first postirradiation mitosis were also scored. Unlike the random distribution of these latter events, the translocation breakpoints showed not only a nonrandom distribution among chromosomes but also the existence of specific sites within chromosomes that were more frequently involved in translocations. The most notable finding was a marked excess of translocations involving the short arm of chromosome 1, in particular, band lp22. The specific types of translocations were random, although the breakpoints were not. Eight of the 12 most frequently involved chromosomal sites were regions in which fragile sites have been mapped in human lymphocytes.
Localization of the human haptoglobin genes distal to the fragile site at 16q22 using in situ hybridization
Authors: Simmers R.N. , Stupans I. , Sutherland G.R.
Published: May 2008

The distamycin A-sensitive fragile site fra(16)(q22) is a precisely localized chromosomal marker. When expressed at metaphase, it visibly separates the chromosome material on either side of the fragile site. Using a cDNA probe encoding both the α and β haptoglobin chains, the haptoglobin loci were found by in situ hybridization to be distal to fra(16)(q22).
In situ localization of human fibronectin (FN) genes to chromosome regions 2p14→p16, 2q34→q36, and 11q12.1→q13.5 in germ line cells, but to chromosome 2 sites only in somatic cells
Authors: Jhanwar S.C. , Jensen J.T. , Kaelbling M. , Chaganti R.S.K. , Klinger H.P.
Published: May 2008

The locations of the genes for fibronectin (FN) on chromosomes of human germ line and somatic cells were determined by in situ molecular hybridization with two 3H-labeled DNA probes, one for the region encoding the cell attachment domain of human FN, the other for the 3’ noncoding and part of the coding region. Pachytene chromosomes of two males and lymphocyte chromosomes of one of these males and a female were used. Two regions of hybridization on pachytene and somatic chromosome 2 (p14→p16 and q34→q36) were found, but not in all individuals. A third region of hybridization was found at 11q12.1→ql3.5 in meiotic, but not with significant frequency in somatic chromosomes. It is not clear if these differences between meiotic and somatic chromosomes, and the large differences between individuals at some of the other hybridization sites, resulted solely from technical factors. The differences between the findings in meiotic and somatic preparations might be due to the presence of four strands in pachytene chromosomes versus only one per somatic chromatid. Individual differences in DNA sequences in the chromosome segment containing the gene, differences in gene locations among individuals, or between meiotic and mitotic chromosomes might account for the other findings. The results confirm some of the earlier studies with cell hybrids that mapped FN genes to chromosomes 2 or 11. The combined findings suggest that some of these loci may be coding for the plasma form of FN and others for the cellular form. The expression of the different FN types by differentiated cells might then depend on the loci that are activated.
Synaptic adjustment at a C-band heterozygosity
Authors: Sharp P.J.
Published: May 2008

An individual male red kangaroo (Macropus rufus) was found to display unaligned kinetochores on one synaptonemal complex. This was the result of “synaptic adjustment” caused by heterozygosity for the size of a C-band near the centromere of this bivalent, the first report of synaptic adjustment at a C-band heterozygosity. The observation suggests a possible method of obtaining further insights into the process of synaptic adjustment.
Suppression of tumorigenicity in somatic cell hybrids
Authors: Kaelbling M. , Klinger H.P.
Published: May 2008

Tumorigénicity assays of 48 intraspecies hybrids between human carcinoma-derived cells of the D98AH2 (HeLa) cell line and normal human diploid cells revealed that most are nontumorigenic in nude mice. Chromosome analysis revealed that these hybrids contained four chromosomes 11, presumably two from each parental cell. Their tumorigenic segregants sometimes, and their tumors always, had lost one or two copies of chromosome 11 (Klinger and Kaelbling, 1986). In this report we present evidence from analyses of DNA restriction fragment length polymorphic (RFLP) markers for the parental cell origin of the 11 which confirms that the four chromosomes 11 of the nontumorigenic hybrids consisted of two from each cell parent, and most notably, that one No. 11 of the diploid parental cell is always absent in cells of tumors that arise when the tumorigenic hybrids are injected into nude mice. We also found that both Nos. 11 of the D98 cells are identical at many RFLP sites on the short arm suggesting that loss of heterozygosity of the 11, or at least of the short arm of the 11, had occurred. Chromosome 11 of the diploid cells thus appears to carry alleles that suppress the tumorigenic potential of the D98 cells when present in two copies, but not in one. It remains to be seen if other chromosomes of the diploid cell effect suppression in concert with the 11.
Heterochromatin in the chromosomes of the gorilla: characterization with distamycin A/DAPI, D287/170, chromomycin A3, quinacrine, and 5-azacytidine
Authors: Schmid M. , Haaf T. , Ott G. , Scheres J.M.J.C. , Wensing J.A.B.
Published: May 2008

The chromosomes of the gorilla were extensively studied with various staining techniques labeling the different classes of heterochromatin. The chromosomal distribution of distamycin A/DAPI-, D287/170-, quinacrine-, and chromomycin A3-positive heterochromatic regions, as well as the nucleolus organizer regions, is described and compared with the karyotypes of other hominoid species. Lymphocyte cultures were treated with low doses of 5-azacytidine during the last hours of culture. This cytidine analog induces distinct undercondensation in 37 heterochromatic regions in the 24 gorilla chromosomes. The 5-azacytidine-induced undercondensations are localized not only in most of the distamycin A/DAPI-bright heterochromatic regions but also in many telomeric C-bands of the chromosomes. Furthermore, 5-azacytidine preserves the somatic pairing between heterochromatic regions from the interphase nuclei into the metaphase stage. The homeologies and differences in the chromosomal localization of the various classes of heterochromatin, 5-azacytidine-sensitive regions, 5-methylcytosine-rich DNA sequences, and satellite DNAs in the gorilla, chimpanzee, orangutan, and man are discussed.
Molecular hybridization to meiotic chromosomes in man reveals sequence arrangement on the No. 9 chromosome and provides clues to the nature of “parameres”
Authors: Mitchell A.R. , Ambros P. , McBeath S. , Chandley A.C.
Published: May 2008

In situ hybridization of male human meiotic material has been used to elucidate the molecular organization of the centromeric region of human chromosome 9. The use of two cloned DN A sequences has shown that the centromere and the secondary constriction of this chromosome contain two separate repeated DNA families. The secondary constriction organizes into “paramere” bodies during pachytene. The individual parameres are comprised of one family of repeated DNA sequences.
The mouse IFN-α (Ifa) locus: correlation of physical and linkage maps by in situ hybridization
Authors: Cheng Z.Y. , Lovett M. , Epstein L.B. , Epstein C.J.
Published: May 2008

The physical location of the mouse IFN-α locus (Ifa) on chromosome 4 was defined by in situ hybridization of a cloned mouse IFN-α probe to metaphase spreads in which one chromosome 4 was present as part of a single metacentric chromosome, all other chromosomes being acrocentric. (This approach greatly facilitates analysis and can be used even when it is difficult to obtain good banding.) Using unhanded chromosomes, the grains were localized over the chromosome 4 part of the metacentric, in a region 0.61 + 0.07 (SD) of the distance from the centromere to the telomere. In Giemsa-banded spreads, the majority of the grains were in the region 4C3→C6. Consideration of these results and of the known linkage maps for mouse and man indicates that the Gait – Aco-1 – Ifa syntenic group spans a distance of ∼14 cM and suggests that the same group on human 9p will also occupy a similarly sized region, with GALT proximal and IFL distal to the centromere.
Ectopic nucleolus organizer regions (NORs) in human testicular tumors
Authors: DeLozier-Blanchet C.D , Walt H. , Engel E.
Published: May 2008

Investigation of nucleolus organizer regions (NORs) in hematopoietic malignancies has indicated that the distribution and rearrangement of these regions may be more important in malignant tissues than is their number. In one of the few studies thus far reported on NORs in human solid tumors, we describe here Ag-NORs in a group of human testicular germ-cell tumors and the corresponding patients. Four of seven malignancies demonstrated consistent ectopic NORs; explanations could include chromosomal rearrangement (insertion?) or derepression of preexisting inactive NORs.
Chromosomal mapping of enzyme loci in the domestic cat: GSR to C2, ADA and ITPA to A3, and LDHA-ACP2 to D1
Authors: Berman E.J. , Nash W.G. , Seuánez H.N. , O’Brien S.J.
Published: May 2008

A panel of 42 rodent × cat somatic cell hybrids segregating individual cat chromosomes in different combinations was used to assign five isozyme structural loci to cat chromosomes. The feline homolog for glutathione reductase (GSR) was mapped to chromosome C2. Adenosine deaminase (ADA) and inosine triphosphatase (ITPA) were located on chromosome A3. Lactate dehydrogenase-A (LDHA) and acid phos-phatase-2 (ACP2) were reassigned to chromosome Dl. Localization of these genes increases the known feline genetic map and extends the known syntenic homologies between the cat and other mammalian species.
Immunogold labeling of metaphase cells
Authors: Perry P.E. , Thomson E.J.
Published: May 2008

A method is presented for the phenotypic identification of metaphase cells stained for chromosome aberration and SCE analysis. The cells are labeled in suspension with antibodies conjugated with colloidal gold, and then chromosome preparations are made using a cytocentrifuge. A silver development (IGSS) procedure is used to enhance the gold labeling for light microscopy. A variety of fixatives may be employed, permitting various cytogenetic and cytochemical staining procedures to be used.
Sublocalization of c-myb to 6q21→q23 by in situ hybridization and c-myb expression in a human teratocarcinoma with 6q rearrangements
Authors: Janssen J.W.G. , Vernole P. , de Boer P.A.J. , Oosterhuis J.W. , Collard J.G.
Published: May 2008

We have sublocalized the human proto-oncogene c-myb by applying two different techniques: in situ hybridization of metaphase spreads and chromosome spot hybridization of flow-sorted chromosomes. For this we used a teratocarcinoma cell line carrying specific chromosome translocations involving the two chromosomes 6 and one chromosome 11. The distribution of the c-myb gene copies on the different translocation chromosomes revealed that c-myb is located in the region 6q21→q23. Because of the close proximity of the c-myb locus to the chromosomal breakpoints in the teratocarcinoma, we investigated whether c-myb was implicated in the development of this tumor. No rearrangement, deletion, or amplification of the gene was detected in the teratocarcinoma cells. Furthermore, the level of c-myb expression was comparable to that of other cell lines of nonhematopoietic origin. These results suggest that c-myb was not affected by the translocation and played no significant role in the development of this teratocarcinoma.
Chromosome anomalies associated with amplification of the adenosine deaminase gene (ADA) in rat hepatoma cells
Authors: Rowl, III P. , Chiang J. , Jargiello-Jarrett P. , Hoffee P.A.
Published: May 2008

Two independently selected series of rat hepatoma cell lines resistant to the drug deoxycoformycin (dCF) were analyzed karyotypically. Several forms of homogeneously staining regions (HSRs) were present on metaphase chromosomes of these cells. In some instances HSRs comprised nearly an entire chromosome, which are among the largest chromosomes in the karyotype. Stable resistance to dCF is acquired in rat cells by overproduction of the enzyme adenosine deaminase (ADA) as a result of amplification of ADA gene sequences. We have localized the amplified ADA gene sequences to HSRs on metaphase chromosomes from both series of dCF-resistant cell lines by in situ hybridization. Based upon the number of ADA gene sequences present and the lengths of the HSRs, we have estimated the size of the amplified unit to range from 450 to 1,000 kb.