Glycoproteins that distinguish different cell types found in amniotic fluid

FISH detection of trisomy 21 in interphase by the simultaneous use of two differentially labelled cosmid contigs

Techniques have been reported in which fluorescence in situ hybridisation (FISH) and cosmid probes are used to detect trisomy 21 (and other abnormalities involving chromosomes X, Y, 13, and 18) on uncultured amniocytes. However the detection rate of trisomy 21 is lower than for the other anomalies owing to a larger number of uninformative results and false negatives. We report the simultaneous use of two differentially labelled cosmid contigs to improve the detection rate of trisomy 21 on uncultured amniocyte samples thus allowing the prenatal diagnosis of Down's syndrome even if only few labelled nuclei are available.

Chromosome instability in cell lineages of amniocyte clones morphologically transformed by Simian virus 40

Seven clonally derived human amniocyte cell lines from independent Simian virus-40 transformation events were analyzed for chromosomal aberrations in the precrisis stage. The distribution of chromosomal aberrations over the haploid complement was nonrandom. With increasing passage number the number of involved chromosomes increased, but the type of aberrations were the same: dicentric chromosomes and translocations due, respectively, to fusion of telomeres and breakage in the centromere regions. Interruptions to telomeres were also evident from extrachromosomal material terminally on the p arms, especially, of chromosomes #7 and #11. The cytogenetic similarities between the present results and those in transfection experiments are mentioned. All seven clones became highly heterogeneous over 10 to 20 passages (i.e., 30-60 population doublings) when, in general, transformed amniocytes enter crisis. The chromosomes which were nonrandomly involved in aberrations exhibited great diversity in types of rearrangements. Thus, for each clone multiple different rearrangements for specific chromosomes were observed in different cells. Most of these aberrations had a single step origin, which implies that breakage occurred repeatedly for the same chromosome in different cells, suggesting that the specific chromosome had become unstable in an earlier cell generation. Thus, we observed development of clonal chromosome instability, a phenomenon not reported for viral transformed cells.

Phosphorylation of keratin and vimentin polypeptides in normal and transformed mitotic human epithelial amnion cells: behavior of keratin and vimentin filaments during mitosis

Analysis by means of two-dimensional gel electrophoresis (IEF) of [32P]orthophosphate-labeled proteins from mitotic and interphase transformed amnion cells (AMA) has shown that keratins IEF 31 (Mr = 50,000; Hela protein catalogue number), 36 (Mr = 48,500), 44 (Mr = 44,000), 46 (Mr = 43,500), as well as vimentin (IEF 26; Mr = 54,000) are phosphorylated above their interphase level during mitosis. Similar studies of normal human amnion epithelial cells (AF type) confirmed the above observations except in the case of keratin IEF 44 whose relative proportion was too low to be analyzed. Immunofluorescent staining of methanol/acetone-treated mitotic transformed amnion cells with a mouse polyclonal antibody elicited against human keratin IEF 31 showed a dotted staining (with a fibrillar background) in all of the cells in late anaphase/early telophase (characteristic "domino" pattern) and in a sizeable proportion of the cells in other stages of mitosis. Normal mitotic amnion cells on the other hand showed a fine fibrillar staining of keratins at all stages of mitosis. Similar immunofluorescent staining of normal and transformed mitotic cells with vimentin antibodies revealed a fibrillar distribution of vimentin in both cell types. Taken together the results indicate that the transformed amnion cells may contain a factor(s) that modulates the organization of keratin filaments during mitosis. This putative factor(s), however, is most likely not a protein kinase as transformed amnion cells and amnion keratins are modified to similar extents. It is suggested that in general the preferential phosphorylation of intermediate-sized filament proteins during mitosis may play a role in modulating the various proposed associations of these filaments with organelles and other cellular structures.

Analysis of normal and abnormal amniotic fluid cells in vitro by cinemicrography

Time-lapse cinemicrography has been used to study cell behaviour and movement in long- and short-term amniotic fluid cultures from various types of fetus. These included several with a neural tube defect (9 anencephalics, 5 spina bifidas, 2 encephaloceles), 1 with an abdominal wall lesion (omphalocele) and 9 controls with no open lesion. In short-term (less than 3 days) amniotic fluid cultures from normal fetuses, non-adherent squamous cells dominate, but there is a small population of cells which, in the longer term (approximately 4 weeks), will form colonies of epithelioid and fibroblastic cells. In addition, there is a further group, called 'AF' by Hoehn et al. (1974), which have the ability to form syncitial strands and are often multinucleated; these cells seem to be trophoblastic in origin. In contrast to the controls, short-term anencephalic cultures contained many adherent cells; these were mainly latex-particle-phagocytosing macrophages and neural cells. In long-term cultures, the neural cells dominate and differentiate into a range of recognizable forms whose type and behaviour seem to depend on cell density, time in culture and extent of cell-cell contacts. In the spina bifida and encephalocele cultures, there were initially far fewer adherent cells than in the anencephalic ones, but, after approximately 2 weeks in vitro, a range of neural cell types could be recognized in addition to those seen in the controls. In the context of prenatal diagnosis, the presence of neural cells certainly indicates that the fetus has a NTD, but the difficulty of standardizing culture conditions implies that any differential diagnosis on the basis or morphology and movement will be difficult. If, as seems likely, the AF cells of Hoehn et al. (1974) are indeed trophoblastic, amniotic fluids from the second trimester may provide a useful source of these cells.