Humangenetik最新文献

The late replication pattern of the short arms of the X chromosomes of Microtus agrestis was studied in female cells and in cells with 2 X chromosomes of male origin by means of the BUdR-Giemsa technique and of 3H-thymidine labelling. The light absorption of Giemsa stained chromosome sections which were unifilarly substituted with BUdR (labelled), was found to be 59.2% of that of unlabelled chromosomes. In female cells, asynchrony of DNA replication of both X chromosomes indicated the presence of facultative heterochromatin in the X2 and euchromatin in the X1. In the male cells only euchromatic X chromosomes were observed in diploid XX and XO cells as well as in triploid XXY, XX and XO cells. The results show that inactivation of an X chromosone in vitro, in cells with more than one originally active X chromosome does not occur even after a culture duration of several years.

Chromosome studies on lymphocyte cultures were performed in 5 patients with AT, 2 of whom had been followed for 4 years. Four out of these patients showed an increased incidence of chromosome-type aberrations. A clonal development was present in one patient, 96% of his metaphases containing a tandem duplication of almost the entire long arm 14. Four years earlier the proportion of these cells was 80%. Two other patients presented a small proportion of cells with an unidentified abnormally long D chromosome. In a total of 724 metaphases from 4 patients 31 dicentric chromosomes were observed, all of a peculiar type; in their formation no chromosome material was lost and they all seem to have arisen by end-to-end fusions. The incidence of chromatid-type aberrations was normal or at the upper limit of control values in all 5 cases. The sister chromatid exchange rate studied with BUDR in 3 patients was found to be normal.

A high frequency of the haemoglobin E gene (HbbetaE) had been found in 1972 in the Ahom, a mongoloid population in Upper Assam. The present study confirms frequencies between 0.3 and 0.35 for this population in a larger sample from different areas. An even higher frequency near 0.5 was found in the Kachari of Upper Assam, a tribe of the tibetoburman Bodo group. HbbetaE frequencies in these groups are compared with the frequencies in the general Assamese population and the austroasiatic Khasi of Meghalaya.

Three new observations of trisomy 4p are reported. Two are due to a maternal translocation t(4;15). The third is due to a "mirror" duplication, it is the first case of trisomy 4p without balanced parental rearrangement. The very characteristic phenotype is compared to that of 13 other patients already reported in the literature.

The complex investigation of the bilogical properties of the triploid cell strain derived from a spontaneous abortus was carried out. Cytomorphological, autoradiographic, cytochemical, biochemical and immunochemical investigation showed that, according to most of the investigated properties, triploid cells did not differ from normal diploid cells. The cells had normal form, were well orientated, revealed expressed fibrillar apparatus and viability in the culture during 15--17 passages. The decrease of the alkaline phosphatase level, increase of acid phosphatase, lactate and malatdehydrogenase and greater nuclei area were the essential differences from the control. The cells had normal mitotic cycle parameters and the antigenic spectrum was practically identical to the normal cells.

A second case of Pi null alpha-1-antitrypsin (AA) deficiency is described. In fact, the serum's subject contains 5 mug of AA per millilitre. With radiolabelled specific antibodies, it is possible to describe the Pi phenotype associated to this deficiency. The pattern which is obtained is like the ordinary Pi M, but 500 times lower than normal values. In contrast to a common deficient variant (ZZ or MZ), the subject tissues do not contain periodic acid-schiff positive inclusion bodies. The "normal" pattern obtained after antigen-antibody crossed electrophoresis, would be in favour of a deficient anomaly hereditarily transmitted.

The acute angle metal depositon technique, discloses a helical chromosome fiber substructure. The microdensitometric analysis of the fiber parameters shows that a fibril 152 A in diameter coils to form the basic chromosome fiber 295 A in diameter with a pitch of 247 A. These figures should be corrected because of the thickening due to metal deposition, the real dimensions would be closer to 112 A for the fibril diameter and 255 A for fiber diameter. The real pitch value is probably somewhat smaller than 247 A (approximatively 200 A) as the values were obtained by analysing slightly stretched fibers. These results support the helical model of the chromosomes fiber organization and show that, most probably, the metaphase chromosome fiber as seen in electron microscopy is the second order of helical packing.

Premature chromosome condensation (PCC) from X-ray induced micronuclei shows a dose-effect relationship in human leukocytes in vitro. Preparations at different culture times without colcemide treatment reveal complex variations of the frequencies of micronuclei and PCC correlated with the fixation time. The positions of PCC patches in the metaphase plate and the frequencies of different PCC types (S and G2) ar independent on the X-ray dose. The latter indicates that the slowing down of the micronuclei in the cell cycle, which is the reason for the formation of PCC, may be an outcome rather of a regulatory phenomenon than of an unspecific physiological damage of the chromatin included in the micronuclei. This is especially evident from labeling experiments with tritiated thymidine, showing that the extent of asynchrony between main nuclei and micronuclei is independent on the X-ray dose. Labeling experiments with tritiated uridine reveal a X-ray dose dependent suppression of RNA synthesis in cells with main nuclei and micronuclei. THE S-phase nature of "pulverized" PCC patches could be verified by incorporation of tritiated thymidine in aound 50%. Staining of centromeric heterochromatin in micronuclei reveal a frequency of micronuclei with centromeric heterochromatin resembling the frequency of G2-phase PCC found in mitoses.

The interaction between peroxidase (donor: hydrogenperoxide oxidoreductase, EC 1.11.1.7) and human alpha2-macroglobulin has been studied by employing starch gel electrophoresis and spectrophotometric assay analysis.

A very large (giant) satellite was observed on one of the D-group chromosomes of a malformed and mentally retarded infant and her father. Detailed cytogenetic studies revealed that the giant satellite represented, in fact, a der(15) chromosome of translocation t(6;15)(p21;p12 or 13). The proposita was trisomic for a part of 6p(6pter leads to 6p21). The father was a balanced carrier, however, the deletion of the short arm of a No. 6 was hard to detect in routine karyotype analysis.