Lore Zech

Identification of human chromosomes by DNA-binding fluorescent agents.

The distribution of DNA along metaphase chromosomes that are not excessively contracted can be visualized in the fluorescence microscope with the aid of fluorescent DNA-binding agents. Additional, characteristic details in the fluorescence patterns are obtained with fluorochromes that bind preferentially to certain chromosomal regions. The highly fluorescent alkylating agent quinacrine mustard (QM) effects discrete, fluorescent labeling of both plant and mammalian metaphase chromosomes, presumably by selective binding to guanine residues in DNA, and is also capable of intercalation in the DNA double helix. Chromosome regions fluorescing particularly strongly with QM have been demonstrated in human metaphase chromosomes 3, 13–15 and Y.A convenient measuring technique has been developed for the rapid and accurate recording of fluorescence patterns in human metaphase chromosomes. These photoelectric recordings of the fluorescence patterns contain far greater detail than can be seen by the human eye.The fluorescence patterns described are based on measurements of about 1,000 human metaphase chromosomes. This new technique of determining fluorescence patterns in human chromosomes should be particularly valuable for the identification of chromosomes 4–5 and the individual types in the 6–12 group. Individual, typical patterns also occur within the groups 13–15, 17–18, and 21–22.

Differential binding of alkylating fluorochromes in human chromosomes

Abstract Human metaphase chromosomes from blood cultures, treated with quinacrine mustard (QM), show a banded pattern of fluorescence, which in the chromosomes with the most strongly fluorescent regions (3, 13–15 and Y) was found to be constant and reproducible. As in plant materials studied earlier, this pattern appears so characteristic that it can be of help for chromosome identification. Improved fluorescence techniques should permit detailed studies on smaller human chromosomes as well. A certain correlation appears to exist between strong capacity for QM-binding and the distribution of heterochromatin as defined by cold treatment (according to Darlington & La Cour) or thymidine labelling-techniques.

Chemical differentiation with fluorescent alkylating agents in Vicia faba metaphase chromosomes

With the purpose of searching for chemical bases for the transfer of differentiation information through metaphase, efforts have been made cytochemically to identify chemical and physiochemical differences between different parts of metaphase chromatin in Vicia. Equipment has been developed for very high resolution quantitative spectrophotometric determinations on chromosomes and for fluorimetric work with low irradiation load on the object. A bifunctional highly fluorescent quinacrine mustard was shown to give chromosome breaks preferentially localized to heterochromatic chromosome regions (identifiable by cold treatment) in the M-chromosome. This and other fluorescent mustards of different types accumulated preferentially in the same regions, which then appear as strongly fluorescent bands. In these bands the fluorescence per unit DNA is higher than in the rest of the chromosome. Possible mechanisms for the fluorochrome-binding are discussed.

DNA-binding fluorochromes for the study of the organization of the metaphase nucleus.

Fluorescent DNA-reagents with different modes of binding have been used for the purpose of identifying chemical differences along metaphase chromosomes. The DNA-distribution pattern along the chromosomes, determined with very high resolution procedures, has been used as reference when studying the differential uptake of different chromosome regions of the compounds. For quantitative measurements of the fluorescence of very small objects a special system has been developed. Several types of plant material and also Chinese hamster have been investigated. Great and reproducible differences in the uptake of the fluorescent reagents by different chromosome regions were observed. In Trillium a good correlation was found between regions reacting with several different fluorescent compounds and heterochromatin as defined by cold treatment. The looseness of the several presently used definitions of heterochromatin is stressed.

Robertsonian chromosomal variation and identification of metacentric chromosomes in feral mice.

Cytogenetic studies of feral mice (M. musculus) from various but predominantly Alpine areas of Switzerland, carried out on random samples collected by spot-checks, established the widespread existence of metacentric chromosomes in the somatic karyotype. Despite the finding of the common occurrence of some of the metacentrics in different places, the examination of the possible homology or heterology by breeding procedures revealed the surprising fact that independence, partial or heterobrachial homology of the metacentric chromosomes prevail among mice from different geographical areas. Thus, the general picture is that of an array of different metacentric chromosomes derived from independent events of Robertsonian variation in the process of evolution. — While heterozygosity with independent metacentrics within a Robertsonian system may have a bearing on the fertility rate of a given mouse population, a more severe impairment of the reproductive capacity must be taken into account in mouse populations which possess different metacentrics with mono- or heterobrachial homologies. These conditions favour the assumption of the existence of a selective system of reproductive barriers further subdividing the species in many, more or less stable, micro-populations. — The chromosomal arms (telocentrics) involved in the formation of the metacentric chromosomes could be identified by Q- and G-banding techniques in combination with the results of crossbreeding, and were assigned to the corresponding telocentric autosomes of the mouse (Comm. Standard. Genet. Nomenclat. for Mice, 1972). Most of the telocentric autosomes of the mouse are included in one or more of the metacentrics found in the feral populations. By means of their isolation in separate lines, these metacentrics may be useful in experimental biology as marker chromosomes of defined identity carrying known linkage groups.

Karyotypic characterization of established cell lines and short-term cultures of human lung cancers

Karyotypic patterns were analyzed from the four major histopathologic groups of human lung cancer: small cell (SCC), squamous cell (SQC), large cell (LCC), and adenocarcinoma (ADC). The studies were performed on banded chromosomes from direct preparations of pleural fluids (one case of SQC and LCC, respectively) and on cell lines. All metaphases were aneuploid and showed highly rearranged chromosomes, with the exception of the direct preparation of the SQC, which was pseudodiploid. The number of marker chromosomes varied-from tumor to tumor. No consistent aberrations could be detected. Special attention was paid to chromosomes 3p-, which was earlier reported to be a characteristic marker chromosome for SCC. We could confirm the presence of that abnormality in two of our six SCC lines. However, we also found a 3p- in a primary SQC culture, in one LCC cell line, and in one ADC cell line. The breakpoint on 3p was not consistent. In some lines, numerical and structural changes of chromosomes #1, #12, #14, and #22 were also noteworthy, although none of these chromosome abnormalities seemed to be correlated to a certain histopathologic group.

Specific chromosome markers involved with chronic T lymphocyte tumors

In a series of 12 patients with chronic T cell tumors, 9 showed abnormalities of the long arm of chromosome #14. The most common aberration was an inversion with breakpoints in q11 and q32, which was seen in 7 patients. One patient had a translocation between chromosomes #9 and #14, with breaks in 9q34 and 14q11, and in another patient, the two long arms of chromosome #14 were fused together in q32, forming a dicentric chromosome. The results confirm earlier suggestions that rearrangements of band 14q11 are involved with T cell tumors and may be of importance for the development of the disease. Chromosome #8 aberrations were seen in seven patients, six of whom had an extra 8q in common. Abnormalities of chromosome #7 occurred in five patients, but the breaks were localized in different bands. The significance of the karyotypic changes in our present and previous series of patients is discussed, together with data from other laboratories.

A new variant translocation (19q+, 22q−) in chronic myelocytic leukemia☆

Abstract A translocation between chromosome 19 and chromosome 22 was found in one out of nine patients with CML. All the remaining eight patients demonstrated a translocation between chromosomes 9 and 22. The clinical pattern of the disease was similar in the patient with the translocation between chromosomes 19 and 22 and in the other CML patients. Thus the presence of the Ph 1 chromosome appears to be more important for the course and pattern of the disease than the location of the translocated fragment.

Quinacrine fluorescence of metaphase chromosomes: Identical patterns in different tissues☆

Abstract The quinacrine mustard fluorescence patterns of the metaphase chromosomes of different tissues of the same plant species were found to be identical. Similar studies of the chromosome regions on human material gave the same result.

The gene for insulin-like growth factor-binding protein-1 is localized to human chromosomal region 7p14-p12

Insulin-like growth factors (IGF) I and II are bound to high-affinity binding proteins in the blood circulation and other body fluids. These IGF-binding proteins are expressed at different concentrations in different tissues and are thought to regulate the activity of IGF I and II. Cloned cDNA for IGF-binding protein-1 (IGFBP1) has been used to verify the location of its gene to human chromosome 7 by Southern blotting to DNA from a human-mouse hybrid cell line. Further, by in situ hybridization the gene was regionally localized to 7p14-p12, and a Mendelian-inherited two-allele BglII restriction enzyme length polymorphism was identified, with the most frequent allele occurring in 53% of the chromosomes.