Molecular biology of the human Y chromosome.
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Amino Acid Sequence↗
Biomedical subjects
W Schempp
Publications and source records attributed to W Schempp.
Comparative cytogenetic studies in tree shrews (Tupaia).
Through use of BrdU replication, RBA-banded karyotypes of Tupaia belangeri, T. chinensis, and T. glis were obtained. A chromosome number of 2n = 62 for T. belangeri is described here for the first time and is confirmed for T. chinensis. All chromosomes between these two phenotypically different species appear to have identical RBA banding patterns; in addition, there is no difference between T. belangeri and T. chinensis in the number and position of nucleolus organizer regions (NORs). The reduced chromosome number of 2n = 60 in T. glis can be explained by a Robertsonian translocation between two acrocentric chromosome pairs, Nos. 10 and 13, of T. belangeri and/or T. chinensis, resulting in the metacentric chromosome pair 1 of T. glis. Furthermore, two chromosome pairs each of T. glis and T. belangeri and/or T. chinensis are not homoeologous, as judged by their RBA patterns. Differences were also found in the number and position of NORs; whereas T. glis displays eight positively stained NORs after AgNO3 staining, there are only four silver-stained NORs in both T. belangeri and T. chinensis. The possibility of geographical isolation as an explanation for the lack of chromosomal differentiation between T. belangeri and T. chinensis is discussed.
Animals↗
Comparative mapping of ZFY in the hominoid apes.
Within our project of comparative mapping of candidate genes for sex-determination/testis differentiation, we used a cloned probe from the human ZFY locus for comparative hybridization studies in hominoids. As in the human, the ZFY probe detects X- and Y-specific restriction fragments in the chimpanzee, the gorilla, the orangutan, and the gibbon. Furthermore, the X-specific hybridization site in the great apes resides in Xp21.3, the same locus defining ZFX in the human. The Y-specific locus of ZFY maps closely to the early replicating pseudoautosomal segment in the telomeric or subtelomeric position of the Y chromosomes of the great apes, again as found in the human. Thus, despite cytogenetically visible structural alterations within the euchromatic parts of the Y chromosomes of the human species and the great apes, a segment of the Y chromosome defined by the pseudoautosomal region and ZFY seems to be more strongly conserved than the rest of the Y chromosome.
Animals↗
The human pregnancy-specific glycoprotein genes are tightly linked on the long arm of chromosome 19 and are coordinately expressed.
The pregnancy-specific glycoprotein (PSG) genes encode a group of proteins which are found in large amounts in placenta and maternal serum. In situ hybridization analyses of metaphase chromosomes reveal that all the human pregnancy-specific glycoprotein (PSG) genes are located on the long arm of chromosome 19 (19q13.2-13.3), overlapping the region containing the closely-related carcinoembryonic antigen (CEA) gene subgroup. Higher resolution analyses indicate that the PSG genes are closely linked within an 800kb SacII restriction endonuclease fragment. This has been confirmed through restriction endonuclease mapping and DNA sequence analyses of isolated genomic clones, which show that at least some of these genes are located in very close proximity. Further, these studies have helped to identify a new member of the PSG gene subfamily (PSG7). DNA/RNA hybridization analyses, using gene-specific oligonucleotide probes based on published sequences, showed that five from six PSG genes tested are coordinately transcribed in the placenta. Due to the close proximity of these genes and their coordinated expression pattern, common transcriptional regulatory elements may exist.
Base Sequence↗
[Diagnosis of multiple endocrine neoplasms type IIa using DNA analysis].
The gene causing MEN IIa has recently being assigned to the pericentromeric region of chromosome 10. We performed linkage analysis using DNA-markers closely related to the chromosomal locus at chromosome 10: MCK II, retinol binding protein cDNA and cTBIRBP-9. Available for the study were EDTA blood from two families. The analysis was positive in two asymptomatic offsprings in one family (B), whereas the markers were not informative in the other family (A). Genetic distance of the informative marker of family A to MEN IIa gene is 2 cM, i.e. a likelihood of 98% (95% up a confidence limit with 5%) for the gene carrier status of two children aged 11 and 7 y old. The following clinical investigation including pentagastrin test, plasma catecholamines and 24 hour urine catecholamines and parathormone was negative until now. We recommend early linkage analysis for establishing the genetic status in offspring of MEN IIa families to focus further screening to those, who are predicted to be gene carrier.
DNA, Neoplasm↗
Deficiency of arginine and lysine causes increase in the frequency of sister chromatid exchanges.
An increase in the rate of sister chromatid exchanges (SCE) was found when V79 Chinese hamster cells were exposed to increasingly severe degrees of arginine and lysine deficiency. The data suggest a possible function of chromosomal proteins, and of histones in particular, in the maintenance of the low normal rate of SCE.
Animals↗
Difference between diploid and aneuploid Chinese hamster cells in replication at mid-S-phase.
Following partial synchronization of the heteroploid Chinese hamster cell line V-79 and of normal diploid lung fibroblasts of the Chinese hamster in culture, their DNA replication during S-phase aws compared by means of a BrdU-incorporation/thymidine pulse technique and Hoechst-Giemsa differential staining of metaphase chromosomes. This comparison indirectly shows the S-phase of the heteroploid cells of V-79 to be 2 h shorter than the diploid cell S-phase. When the thymidine pulse is applied to diploid lung fibroblasts at mid-S-phase, differential staining colours metaphase chromosomes a pale blue. Performing the corresponding experiment with V-79 cells, neither a pale blue nor dark red staining is obtained, but rather an intermediate shade, showing prominently dark staining regions in parts. The pause in DNA synthesis observed at mid-S-phase of the diploid Chinese hamster lung fibroblasts seems to be omitted at mid-S-phase of the V-79 cells.
Aneuploidy↗
Ellobius lutescens Th. (Rhodentia, Microtinae): Q-, R-, and replication banding patterns. Chromosome 1 polymorphism in the male and presumptive heterogamety in the female.
Five specimens of Ellobius lutescens, four males and one female, were studied by several banding methods. Structural polymorphism occurred in the longest chromosome pair of the karyotype of two males: a pericentric inversion in one animal and a paracentric inversion in the other. In the female studied, one chromosome 1 differs from those of the males by a marked elongation of a proximal euchromatic band in the long arm. Thus, the female seems to represent the heterogametic sex. Chromosome 9 showed the same banding pattern in both sexes. The possible meaning of this chromosome constitution for the sex-determining mechanism of E. lutescens is discussed.
Animals↗
Comparison of thymidine, fluorodeoxyuridine, hydroxyurea, and methotrexate blocking at the G1/S phase transition of the cell cycle, studied by replication patterns.
Cultures of human amniotic fluid cells and fibroblasts were temporarily blocked by the replication inhibitors thymidine (dT) surplus, fluorodeoxyuridine (FdU), hydroxyurea (HU), or methotrexate uridine (MU). The respective arresting point at G1-S transition and the homogeneity of the blocked cell population were determined by means of BrdU replication patterns. Most variation of patterns were found after HU. After MU, cells were arrested before the onset of replication, while with dT surplus of FdU an arresting point in early S seemed more likely.
Amniotic Fluid↗
Demonstration of replication patterns corresponding to G- and R-type banding of chromosomes after partial synchronization of cell cultures with BrdU or dT surplus.
A standard protocol is reported for the highly efficient demonstration of replication patterns corresponding to R-type and G-type banding.
Amniotic Fluid↗
Decrease of DNA synthesis in amniotic fluid cells during the middle part of S-phase revealed by differential chromosome staining after incorporation of BrdU.
The time sequence of DNA replication in partially synchronized human amniotic fluid cells has been analysed, employing BrdU incorporation techniques.--Regardless of the interval between removal of the methotrexate/uridine block and addition of BrdU during S-phase, the treatment results in an R-type replication pattern. Conversely, replacement of BrdU containing medium by another one with thymidine yields G-type replication patterns. A thymidine pulse during the first 4 h of S-phase results in R-type replication patterns; from 7--10 h after block removal it produces G-type pattern. In between, only faint red staining dots can be found indicating a marked decrease of replicational activity during the middle part of the S-phase.
Amniotic Fluid↗
Silver-staining specificity in metaphases after incorporation of 5-bromodeoxyuridine (BUDR).
Silver staining is reported to be reduced in chromatin substituted by BUDR. This quenching effect allows for the demonstration of replication patterns and differential chromatid staining. Though the differentiation, as compared to other staining techniques, is of inferior quality, it is of theoretical importance concerning the effect of BUDR incorporation into chromatin.
Bromodeoxyuridine↗