Determination of sex chromosomal constitution and chromosomal origin of drumsticks, drumstick-like structures, and other nuclear bodies in human blood cells at interphase by fluorescence in situ hybridization

Can sex be determined from a blood smear?

Objective: Originally, this blind study was designed to check whether blood smears constitute reliable tools to determine sex. However, when we analyzed our data some interesting findings immerged and in this paper we try to highlight them.

Material and Methods: 74 blood smears (35 women and 39 men) have been performed and then stained. 200 polynuclearneutrophils were examined for nuclear appendages and classified into four groups: neutrophils with form A, B or C appendages and neutrophils without any appendage.The difference (A-C) was calculated for each slide. The “cytologic sex” was defined as a male in case of a negative value and as a female otherwise.

Results: Neutrophils bear the same amount of appendages in both genders (p=0.37). But the number of form A is greater in females (p<0.0001) and form C is much more frequent in males (p<0.0001), that is why, the difference A-C is the best way to differentiate between both sexes.The distribution histogram of A-C in women shows a multimodal histogram contrary to men’s graphwhich is a bell-shaped curve. The menstrual cycle was incriminated in this feature.

Conclusion: Blood smear is a reliable tool to determine gender.

Conflict of interest:None declared.

A longitudinal study of human age-related chromosomal analysis in skin fibroblasts

Previous chromosomal analyses related to human aging used mainly cross-sectional data on metaphase chromosomes. However, it is difficult to directly relate the cross-sectional results to the specific type(s) of chromosomal mutations possibly occurring within a specific individual with advancing age, because the unique genetic endowment of each individual for longevity might be a modulating factor. We therefore have performed, for the first time, a longitudinal study of both numerical and structural chromosome analyses of skin fibroblasts at interphase and at metaphase derived from eight donors participating in the Baltimore Longitudinal Study. We have used the FISH method with chromosome-specific DNA probes and the data on total aneuploidy of 17 different chromosomes in each of the 16 cell cultures (2 from each of eight individuals) indicate that significantly higher percentages of aneuploid cells are detected at interphase than at metaphase. Mostly, the levels of chromosome-specific aneuploidy increase with the donor's advancing age and, in most individuals, chromosomes 1, 4, 6, 8, 10, and 15 show significantly higher frequencies of aneuploidy at interphase than those of the 11 other chromosomes studied. Although the significance of relatively higher levels of aneuploidy of certain chromosomes with aging remains unclear, it is intriguing to note that some of these chromosomes, such as 1, 4, and 6, have already been assigned to harbor senescence genes and chromosome 8 is known to house the gene for Werner Syndrome (progeroid syndrome), which shows very limited proliferative capacity of fibroblasts. It is conceivable that the degree and/or type of chromosome-specific aneuploidy might have some gene dosage effects in the control of cellular proliferation and selection during aging. We also show that a combination of both interphase and metaphase aneuploidy analyses provides more comprehensive and insightful information on intraindividual cellular dynamics and chromosomal aneuploidy as a function of age. Occasionally, very small proportions of cells in two individuals showed age-related structural chromosome aberrations, such as an acentric fragment derived from an X chromosome and an achromatic gap in chromosome 7. Thus, a comparative analysis of both intra- and interindividual longitudinal studies is very useful in detecting the pattern(s) of chromosome-specific alterations with increasing age.

Age-related aneuploidy analysis of human blood cells in vivo by fluorescence in situ hybridization (FISH)

All prior studies on human age-related chromosomal analysis were done using only metaphase figures derived from lymphocyte cultures in vitro. However, we believe that this procedure may provide only partial information, since the chromosomal abnormalities probably hidden in non-dividing and/or terminally differentiated leukocytes will not be detected by this method. We, therefore, have attempted to analyze the nature and extent of chromosome-specific aneuploidy at interphase by fluorescence in situ hybridization (FISH) in differentiated myeloid cells in vivo derived from various age-group people. Our data from an analysis of 30,032 cells derived from 12 healthy donors indicate that there is an increase in the mean percentages of myeloid cells with chromosome-specific aneuploidy in the older groups as opposed to that of the younger groups. This increase is applicable to all the three cell types examined (promyelocytes, metamyelocytes and polymorphs). In both the younger and older females, the relatively higher mean frequencies of cells with aneuploidy were noted for chromosome nos. 4, 6 and the X, whereas the lowest mean frequencies of cells with aneuploidy were consistently observed for chromosome no. 3. In the younger and older male donors, similar to the female donors except the X chromosome the higher percentages of aneuploid cells were observed for chromosome nos. 4 and 6 whereas the lowest mean frequencies of aneuploid cells were noted for chromosome no. 3. Among the five autosomes studied, chromosome no. 3 consistently yielded the lowest frequency of aneuploidy in all the three cell types derived from both the younger and older groups of males and females. This could presumably mean that the maintenance of a very high frequency of cells with disomy for chromosome no. 3 might be more beneficial for the process of survival and/or differentiation of myeloid cells as compared to that of other autosomes such as chromosome nos. 4 and 6. Among the five autosomes studied, chromosome no. I exhibited the highest rate of increment in the aneuploidy values of both males and females with advancing age.

Chromosomal analysis in young vs. senescent human fibroblasts by fluorescence in situ hybridization: a selection hypothesis

Almost all previous studies on chromosomal analysis related to in vitro aging of human fibroblasts were done using only metaphase chromosomes. However, this procedure may provide only partial information since the aneuploidy presumably hidden in interphase cells would remain undetected. For this reason, we have analyzed aneuploidy both at interphase and at metaphase. Female (IMR-90) and male (IMR-91) cells were grown from the lowest to the highest population doubling levels and aneuploidy analysis was done by FISH with alpha-satellite DNA probes of 15 autosomes and two sex chromosomes. Our data on total aneuploidy in young cells indicate that significantly higher proportions of cells with aneuploidy can be detected at interphase than at metaphase. This presumably indicates that during active division of young cells, more aneuploid than diploid cells are selected against entry to mitosis. In contrast, interphase senescent cells from both strains show significantly fewer aneuploid nuclei than do young cells at interphase. This probably indicates that during senescence, there is greater selective pressure in the culture against long-term survival of aneuploid cells than against survival of diploid cells. Our study shows that cellular dynamics with respect to aneuploidy involving various chromosomes differs significantly at interphase and at mitosis during in vitro aging of human fibroblasts, and we propose a 'Selection Hypothesis' as an explanation to our findings.

Dynamic organization of DNA replication in mammalian cell nuclei: spatially and temporally defined replication of chromosome-specific alpha-satellite DNA sequences

Five distinct patterns of DNA replication have been identified during S-phase in asynchronous and synchronous cultures of mammalian cells by conventional fluorescence microscopy, confocal laser scanning microscopy, and immunoelectron microscopy. During early S-phase, replicating DNA (as identified by 5-bromodeoxyuridine incorporation) appears to be distributed at sites throughout the nucleoplasm, excluding the nucleolus. In CHO cells, this pattern of replication peaks at 30 min into S-phase and is consistent with the localization of euchromatin. As S-phase continues, replication of euchromatin decreases and the peripheral regions of heterochromatin begin to replicate. This pattern of replication peaks at 2 h into S-phase. At 5 h, perinucleolar chromatin as well as peripheral areas of heterochromatin peak in replication. 7 h into S-phase interconnecting patches of electron-dense chromatin replicate. At the end of S-phase (9 h), replication occurs at a few large regions of electron-dense chromatin. Similar or identical patterns have been identified in a variety of mammalian cell types. The replication of specific chromosomal regions within the context of the BrdU-labeling patterns has been examined on an hourly basis in synchronized HeLa cells. Double labeling of DNA replication sites and chromosome-specific alpha-satellite DNA sequences indicates that the alpha-satellite DNA replicates during mid S-phase (characterized by the third pattern of replication) in a variety of human cell types. Our data demonstrates that specific DNA sequences replicate at spatially and temporally defined points during the cell cycle and supports a spatially dynamic model of DNA replication.