Structure and variability of human chromosomes analyzed by recent techniques

Summary Besides the AT-specific fluorochromes, GC-specific fluorescent antibiotics are now available for chromosomal analysis. Chromosomal bands represent large accumulation of DNA sequences with similar AT:GC ratio. These uniform differences from the mean AT:GC ratio in the bands can be explained only by at least partial repetition of short DNA sequences in these regions. By comparison of various staining techniques more information also on the constitutive heterochromatin in man becomes available. The human NOR region exhibits a complex organization when studied by various basespecific fluorochromes and silver staining. The DNA-specific fluorochromes are also useful tools in cytophotometric DNA measurements.     

Relationships between body fat measured by DXA and subcutaneous adipose tissue thickness measured by Lipometer in adults

The aim of this study was to examine the relationships between body fat measured by DXA and subcutaneous adipose tissue layers (SAT-layers) measured by LIPOMETER in adult males (n=28) and females (n=53). Body height and mass were measured and BMI was calculated (kg/m2). Measurements of the thicknesses of SAT-layers by LIPOMETER were performed at 15 original body sites. Body composition was measured using DXA. Total body fat % measured by DXA was highly dependent on the SAT-layers in the upper back and inner thigh in males (87.1%, R(2)x100) and the lateral chest, biceps, and calf in females (78.5%, R(2)x100). There were gender differences in trunk fat mass and right hand and leg fat mass calculation using specific SAT-layers. In conclusion, our results indicate that there are close relationships between SAT-layers and body fat measured by DXA. However, there are big differences between genders.     

Giemsa banding,quinacrine fluorescence and DNA-replication in chromosomes of cattle (Bos taurus)

Almost all the 30 chromosome pairs of cattle can be identified by their banding patterns made be visible by a Giemsa staining technique described previously. The banding pattern of the X chromosome shows striking similarities with the banding pattern of the human X chromosome. — The centromeric region of the acrocentric autosomes contains a highly condensed DNA. This DNA is removed by the Giemsa staining procedure as can be shown by interference microscopic studies. If the chromosomes are stained with quinacrine dihydrochloride these centromeric regions are only slightly fluorescent. — Autoradiographic studies with ³H-thymidine show that the DNA at the centromeric regions starts and finishes its replication later than in the other parts of the chromosomes.     

Sexchromatin und Kerngrö\e im Zellzyklus

Zusammenfassung Die DNS-Synthese der Zellen in menschlichen Fibroblastenkulturen wird durch das Umsetzen der Kultur weitgehend synchronisiert. 24 Std nach dem Umsetzen erfolgt ein Mitoseschub. Die Sexchromatin-Häufigkeit in weiblichen Kulturen ist in der Periode nach dem Mitoseschub niedriger als vor dem Mitoseschub.Durch Kombination von histophotometrischen Methoden und Autoradiographie nach ³H-Thymidin-Markierung lassen sich vier Zellstadien unterscheiden: 1. frühe G1-Kerne: Kerne, die maximal 8 Std nach einer Mitose sind; 2. späte G1-Kerne: Kerne, die sich minimal 8 Std nach einer Mitose befinden; 3. G2-Kerne und 4. Tetraploide Zellen. Kerne in der DNS-Synthese müssen vernachlässigt werden, haben aber auf die Resultate keinen Einfluß.Es zeigt sich, daß bei weiblichen Zellen frühe G1-Kerne nur in 32% der Fälle Sexchromatin enthalten, späte G1-Kerne in 58% und G2-Kerne in 82%. Die Sexchromatin-Häufigkeit steigt also mit dem Zellalter im Verlauf des Zellzyklus an. Es wird zur Diskussion gestellt, daß das Sexchromatin meist erst einige Zeit nach der Telophase gebildet wird.Bei den Kernflächenbestimmungen zeigt sich ein Anstieg der Kerngröße mit dem Zellalter. Die Verdopplung der Kern-DNS bei der Replikation führt nicht zu einer Verdopplung der Kernfläche, sondern nur zu einer geringergradigen Vergrößerung. Tetraploide Gl-Kerne haben bei gleichem DNS-Gehalt eine signifikant größere Kernfläche als diploide G2-Kerne.

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Sex chromatin and nuclear size during the cell cycleCombined histophotometric and autoradiographic studies on human fibroblast cultures

DNA synthesis of cultured human fibroblasts is partly synchronized when cells are transplanted into a new culture vessel. A peak in mitosis frequency occurs 24 hours after transplantation. In cultures from females sex chromatin is less frequently observed after the mitotic peak. — By use of combined histophotometric and autoradiographic techniques after labeling with ³H-thymidine four groups of nuclei can be distinguished: 1. early G1-nuclei; these are nuclei, which had passed through mitosis up to 8 hours previously; 2. late G1-nuclei, nuclei which had been in interphase for more than 8 hours; 3. G2-nuclei, and 4. tetraploid cells. Cells about to replicate DNA have been neglected, but do not influence results. — Sex chromatin is found only in 32% of early G1-nuclei, in 58% of late G1-nuclei and in 82% of G2-nuclei. There is an increase in sex chromatin frequency during the cell cycle. It is suggested that the sex chromatin body is newly formed, but only some time after telophase. — Measurements of nuclear areas show an increase of mean nuclear area during the cell cycle. Duplication of nuclear DNA is not followed by any duplication of nuclear area, but causes only a less pronounced enlargement. Although containing the same DNA-amount, tetraploid G1-nuclei are larger than diploid G2-nuclei (Zusammenfassung see p. 434).

     

Fluorescenzuntersuchungen über die Längenvariabilität des Y-Chromosoms beim Menschen

Zusammenfassung Die Länge des Y-Chromosoms ist bei verschiedenen Männern bekannterweise von wechselnder Größe. Nach Färbung mit Atebrin zeigt dieses Chromosom eine auffällig starke Fluorescenz im distalen Abschnitt des langen Arms. Es lassen sich somit 3 Abschnitte im Y-Chromosom unterscheiden: 1. der kurze Arm, 2. der unauffällig fluorescierende proximale Teil und 3. der sehr stark fluorescierende distale Abschnitt des langen Arms. In dieser Arbeit wurden in Chromosomenpräparaten von 40 normalen Männern mit verschieden langem Y-Chromosom Messungen dieser 3 Abschnitte durchgeführt. Es zeigte sich, daß die Längenvariabilität des Y-Chromosoms beim Menschen vor allem auf die wechselnde Größe des distalen, stark fluorescierenden Anteils des langen Arms zurückzuführen ist. Aber auch der proximale, schwach fluorescierende Teil des langen Arms zeigt eine gewisse Längenvariabilität. Für den kurzen Arm des Y-Chromosoms konnte in dieser Untersuchung keine statistisch gesicherte Längenvariabilität gefunden werden.

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Analysis of the length variation in the human Y chromosome by aids of the quinacrine fluorochrome method

Summary The human Y chromosome exhibits a wide variation in length. After staining with quinacrine this chromosome shows a heavy fluorescence in the distal portion of the long arm. Consequently there may be distinguished 3 parts within the Y chromosome: 1. the short arm, 2. the weakly fluorescent proximal portion of the long arm and 3. the strongly fluorescent distal portion of the long arm. Measurements of these 3 parts were perfomed in chromosome preparations of 40 normal males. There can be shown, that the variation in the length of the human Y chromosome is the result mainly of a variation in the length of the strongly fluorescent distal portion of the long arm. The weakly fluorescent proximal portion of the long arm also shows a modest variation in length. The short arm showed no statistical significant variation in length.

     

Der Zellzyklus in Fibroblastenkulturen vom Menschen

Summary Autoradiography using H³-Thymidin and Feulgen photometry of nuclear DNA-content were carried out on human euploid fibroblast cultures.The average durations of S- and G2-periods are about 9 hours and 5 hours respectively, with only minor variation. The duration of G1-period may vary from a few hours to more than 20 hours.A combined study of H³-thymidin uptake and Feulgen photometry on the same cell nuclei showed that all cells whose DNA-content places them into the S-period are labelled when they are fixed immediate after a H³-thymidin puls. After continuous H³-thymidin uptake for 5 hours, all S- and G2-nuclei are labelled, whereas the G1-nuclei remain unlabelled.The Feulgen histogramm as well as grain counts over labelled nuclei indicate a constant rate of DNA synthesis during S-period.     

Increased sister chromatid exchange events in the human late replicating X

Summary Human female blood cultures were labeled with BrdU for detecting sister chromatid exchanges (SCEs) by the Hoechst 33258 fluorescence technique. Late labeling with ³H-thymidine and autoradiography allowed the identification of the late replicating X. The mean number of SCEs in the cells was 13. The isopycnotic X showed an exchange frequency according to its relative length in the karyotype; in the late replicating X a doubled number of SCE events was observed.     

ROC analysis of subcutaneous adipose tissue topography (SAT-Top) in female coronary heart disease patients and healthy controls

The aim of this study was to investigate whether subcutaneous adipose tissue topography (SAT-Top) is different in female CHD patients (n=26) and healthy controls (n=36) matched to age, body size, weight, and BMI. The thicknesses of SAT layers were measured by LIPOMETER at 15 specified body sites. To calculate the power of the different body sites to discriminate between CHD women and healthy controls, receiver operating characteristic (ROC) curve analysis was performed. For each parameter, sensitivity and specificity were calculated at different cutoff points. CHD women showed a significant decrease to 78.36% (p=0.012) at body site 11-front thigh, 73.10% (p=0.012) at 12-lateral thigh, 72.20% (p=0.009) at 13-rear thigh, 66.43% (p<0.001) at 14-inner thigh, and 49.19% (p<0.001) at 15-calf. The best discriminators analysed by ROC curves between female CHD patients and healthy controls turned out to be calf and inner thigh (optimal cut off values: calf: 3.85 mm and inner thigh: 11.15 mm). Stepwise discriminant analysis identified the body sites calf, lateral chest, and inner thigh as significant. In conclusion, information was obtained on the extent to which SAT thickness at each measured body site is able to discriminate between the two subject groups. The good discrimination results obtained for the present dataset are encouraging enough to recommend applying LIPOMETER SAT-Top measurements in further studies to investigate individual risks for CHD.