The locus for acid phosphatase (ACP1) had been alternately assigned to two conflicting regions on the short arm of chromosome 2. We present a clinical and cytogenetic report of one patient who has an interstitial deletion of 2, del(2) (p23p25.1), and a cytogenetic study of another cell line with an interstitial deletion of 2p (p23.1p25.1). Because both patients are heterozygotes for ACP1, the assignment of ACP1 to 2p25.1----pter is supported.

Cytogenetic evaluation of serially subcultivated human endothelial cells revealed significant differences between cultures derived from fetal umbilical cords and cultures derived from various vessel sites in adults. A rapid increase in the prevalence of polyploid cells, to levels of 100% in many cases, was detected in human umbilical vein endothelial cell cultures but not in endothelial cell cultures from adult vessels. Because the development of polyploidy has been viewed as one signpost of in vitro senescence, it may be that these in vitro observations of high levels of polyploidy are a reflection of the fact that umbilical tissue is at the end of its in vivo developmental lifespan when studied. Consistent karyotypic alterations also were observed in two clones from adult human abdominal aorta, even though these cultures exhibited low percentages of polyploid cells. Cultures of one clone exhibited a trisomy of chromosome 11, on which there are at least three onc gene loci, and a deletion of chromosome 13 through band q14. A loss of band 13q14 is a prezygotic chromosomal lesion known to predispose to retinoblastoma. In the other clone, two cell populations were observed, and each displayed a chromosomal abnormality. A trisomy of the long arm of chromosome 2 was noted in one cell population via a marker chromosome involving 2 and 14. The other cell population exhibited an abnormality of chromosome 2. Neither of these karyotypic alterations was detected in the parent culture from which the clones were derived. The results reported in this study have both practical and theoretical implications. The high incidence of polyploidy in serially cultivated umbilical cultures as well as the occurrence of chromosomal changes in umbilical and aortic cultures testify to the need for cytogenetic monitoring of cell cultures even though they are derived from presumably normal tissue. Cytogenetic changes in the endothelium may be important in atherogenesis and other pathologic states. The conversion of diploid endothelial cells into polyploid endothelial cells may provide a convenient model cell system for studying mechanisms of the development of polyploidy in cells and their relationship to in vitro senescence.

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High-resolution Giemsa-trypsin bands can be induced in the chromosomes of human skin fíbroblast cultures exposed to actinomycin D (final concentration, 2 µg/ml) before harvest.

In this paper methodology is described which yields three-way Giemsa differentiation (light-medium-dark) in human metaphase chromosomes exposed to 5-bromodeoxyuridine (BrdU) for 3 DNA synthetic periods (or exposed for 2 DNA synthetic periods and removed from exposure for the third) by means of which all of the sister chromatid exchanges (SCEs) occurring during (or shortly after) S1, S2 and S3 can be accurately counted and distinguished from one another. Using these methods it has been demonstrated that approximately twice as many SCEs occur during the first S-period in the presence of the drug (labeling=B1T0XT0B1)1 as occur during the second S-period (labeling=B2B1XT0B2)1. The three-way differentiation pattern is thought to result from a stepwise decrease in the amount of BrdU incorporated during the first, second and third DNA synthetic periods. These methods can also be used to differentiate between unlabeled (T2T0) and unifilarly labeled (B1T2) sister chromatids and are potentially useful in the detection of sub-chromatid exchanges (none were detected).

Two members of the KOX gene family, ZNF23 (KOX16) and ZNF32 (KOX30), have been mapped by in situ hybridization to chromosome regions 16q22 and 10q23-q24, respectively. The map location of ZNF23 and ZNF32 placed these zinc finger protein genes near to chromosome loci that, under certain in vitro conditions, are expressed as fragile sites (FRA16B, FRA16C) and (FRA10D, FRA10A, FRA10B and FRA10E). Human zinc finger gene ZNF32 maps to a chromosome region on 10q23-24 in which deletions have been observed associated with malignant lymphoma on 10q22-23 and with carcinoma of the prostate on 10q24. ZNF23 is located on 16q22 in a chromosomal region that has been involved in chromosome alterations characteristic of acute myeloid leukemia. A second Kox zinc finger gene (ZNF19/KOX12) was recently mapped to the same chromosome region on human chromosome 16q22. In the analogous murine position, the murine zinc finger genes Zfp-1 and Zfp-4 are found in the syntenic 16q region of mouse chromosome 8. Thus, ZNF19 and ZNF23 might be members of an evolutionarily conserved zinc finger gene cluster located on human chromosome 16q22.

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