Nature of telomere dimers and chromosome looping in human spermatozoa

Specific and well-organized chromosome architecture in human sperm cells is supported by the prominent interactions between centromeres and between telomeres. The telomere-telomere interactions result in telomere dimers that are positioned at the nuclear periphery. It is unknown whether composition of sperm telomere dimers is random or specific. We now report that telomere dimers result from specific interactions between the two ends of each chromosome. FISH using pairs of subtelomeric DNA probes that correspond to the small and long arms of seven human chromosomes demonstrates that subtelomeres of one chromosome are brought together. Statistical analysis confirmed that telomere associations could not result from the random proximity of DNA sequences. Therefore, chromosomes in human sperm nuclei adopt a looped conformation. This higher-order chromosome structure is most likely required for chromosome withdrawal/decondensation during the early fertilization events leading to zygote formation.

Double in situ hybridization in combination with digital image analysis: a new approach to study interphase chromosome topography

Double in situ hybridization with mercurated and biotinylated chromosome specific DNA probes in combination with digital image analysis provides a new approach to compare the distribution of homologous and nonhomologous chromosome targets within individual interphase nuclei. Here we have used two DNA probes representing tandemly repeated sequences specific for the constitutive heterochromatin of the human chromosomes 1 and 15, respectively, and studied the relative arrangements of these chromosome targets in interphase nuclei of human lymphocytes, amniotic fluid cells, and fibroblasts, cultivated in vitro. We have developed a 2D-image analysis approach which allows the rapid evaluation of large numbers of interphase nuclei. Models to test for a random versus nonrandom distribution of chromosome segments are discussed taking into account the three-dimensional origin of the evaluated 2D-distribution. In all three human diploid cell types the measurements of target-target and target-center distances in the 2D-nuclear image revealed that the labeled segments of the two chromosomes 15 were distributed both significantly closer to each other and closer to the center of the nuclear image than the labeled chromosome 1 segments. This result can be explained by the association of nucleolus organizer regions on the short arm of chromosome 15 with nucleoli located more centrally in these nuclei and does not provide evidence for a homologous association per se. In contrast, evaluation of the interphase positioning of the two chromosome 1 segments fits the random expectation in amniotic fluid and fibroblast cells, while in experiments using lymphocytes a slight excess of larger distances between these homologous targets was occasionally observed. 2D-distances between the labeled chromosome 1 and 15 segments showed a large variability in their relative positioning. In conclusion our data do not support the idea of a strict and permanent association of these homologous and nonhomologous targets in the cell types studied so far.

Interstitial deletion of the short arm of chromosome 3 (3p14)

Deletions of 3p usually involve the terminal portion (3p25). An interstitial deletion of a proximal 3p segment (3p14) was detected at amniocentesis. The clinical and cytogenetic characteristics of this case and of three previously published cases are reviewed. Cardiovascular and gastrointestinal malformations have not been reported before in association with this particular chromosome abnormality.

Trisomy and tetrasomy for long arm of chromosome 1 in near-diploid human endometrial adenocarcinomas

Karyotypic analysis by R-banding after short-term culture, carried out on 7 cases of human endometrial adenocarcinoma, showed in 4 of these a trisomy or a tetrasomy for the long arm of chromosome I. In the 4 cases, these imbalances were due to rearrangements involving centromeric or para-centromeric break-points: 46,XX,-16, +der(1q16p) t(1;16)(1p16q;1q16p); 46,XX,-21, +der (1q21q)t(1;21) (1p21p;1q21q); 46,XX, -21, +der(21) t(1;21)(q11;p13); 48, XX, +2, +i(1q). Two other cases showed only a numerical aberration: 47, XX, +10 and 47, XX, +12. In the last case, only cells with apparently normal karyotype were seen. In the 4 cases with an anomaly of chromosome I, two normal I chromosomes coexisted with abnormal elements. This shows that the rearrangement very likely occurred in G2 phase of the cell cycle.

Sideroblastic anemia associated with thrombocytosis and a chromosome 3 abnormality

A unique patient with sideroblastic anemia and thrombocytosis with a recurrent and ultimately fatal thromboembolic phenomenon is described. Cytogenetic analysis of bone marrow metaphases revealed a pseudodiploid chromosome complement, 46,XY,ins(3;3)(q26;q21q26). The association of thrombocytosis and ins(3;3) in patients with preleukemia or myelogenous leukemia has been reported previously. The association of ins(3;3) and thrombocytosis in our patient with sideroblastic anemia suggests that the disorder may involve a hematopoietic progenitor cell capable of giving rise to all three cell lineages. Our findings also support the suggestion that a gene on the long arm of chromosome #3 may encode a protein that, at least in part, regulates megakaryopoiesis.

A case of rhabdomyosarcoma of the bladder with a (2;5) chromosomal translocation in peripheral lymphocytes

Chromosome analysis was performed on peripheral blood lymphocytes of a patient with rhabdomyosarcoma of the urinary bladder. It showed a reciprocal t(2;5) translocation with the breakpoints at 2q37.3 and 5q31.3. This is the first report of such an anomaly in the peripheral lymphocytes of a patient with rhabdomyosarcoma of the urinary bladder.

Acute megakaryoblastic leukaemia with 3q inversion and elevated thrombopoietin (TSF): an autocrine role for TSF?

A patient with acute megakaryoblastic leukaemia is described in whom exactly the same paracentric inversion of 3q was detected as in three previously documented cases. The patient's serum thrombopoietin (TSF) was significantly raised. Based on these findings we postulate a role for a gene (? oncogene) on chromosome 3q in thrombopoietin production. Abnormalities of 3q may assist in delineating a subgroup of acute nonlymphocytic leukaemia, namely acute megakaryoblastic leukaemia.

Fragile sites on human chromosomes: description and clinical significance

The fragile sites of human chromosomes are specific sites that are characterized by a tendency to show gaps, multiradial figures, acentric fragments, and deleted chromosomes on microscopy. These characteristics seem to reflect an inherent fragility at the site, although the underlying biochemical cause of fragile sites is unknown. Investigators have proposed several categories of fragile sites: "rare" or "heritable," "common," and "constitutive." Although the clinical significance of most fragile sites is unknown, fragile site Xq27.3 is associated with one form of X-linked mental retardation. In this article, the three types of chromosome fragile sites are described, and their possible relevance to chromosomal breakage that results in birth defects or cancer is discussed.

Light and scanning electron microscopy of the same human metaphase chromosomes

A technique has been developed to examine the same G-banded human metaphase chromosomes, first in the light microscope and then in the scanning electron microscope (SEM). A structural involvement in chromosome banding was confirmed by a positional correlation between the G-positive bands observed in the light microscope and the circumferential grooves between the quaternary coils of the metaphase chromosomes, observed in the SEM. In further support of this the regions between the grooves showed a positional relationship with the G-negative or reverse (R) bands. The examination of slightly extended metaphase chromosomes in the light microscope demonstrated that the G-banding pattern corresponded to that described by the Paris nomenclature for metaphase chromosomes. The arrangement of the circumferential grooves of the same chromosomes, observed in the SEM, was shown to relate to that described by the Paris nomenclature for prometaphase chromosomes. Therefore, using the SEM it is possible to demonstrate the details of prometaphase banding in metaphase chromosomes.

Persistent Epstein-Barr virus infection associated with monosomy 7 or chromosome 3 abnormality in childhood myeloproliferative disorders

This report deals with myeloproliferative disorders associated with chronic, persistent Epstein-Barr virus (EBV) infection and with monosomy 7 and aberrations concerning chromosomes 3 and 5. Altogether five children were affected, their age ranging from 1 to 4 years at time of clinical diagnosis. Principal symptoms were: hepatomegaly, splenomegaly, recurring upper respiratory tract infection and anaemia. The serum IgG level remained persistently increased. Anti EBV antibody concentrations were measured over a period of 9 months to 6 years, demonstrating persistently increased concentrations of IgG antibodies to viral capsid antigen (VCA) and against early antigen (EA). In three patients IgA antibodies were also studied and were found to be elevated. Within 2-5 years two children developed chronic myelomonocytic leukaemia from the chronic myeloproliferative syndrome. A third patient who initially was diagnosed as chronic myelomonocytic leukaemia developed acute leukaemia within a period of 12 months. A fourth patient with myeloproliferative syndrome went into spontaneous remission after an observation period of 2 years. A fifth patient, the only one with translocation t(3;5)(q27;q33), displayed symptoms and a clinical course that can best be characterized as juvenile chronic myelocytic leukaemia. The clinical, haematological, serological and cytogenetic findings may be related.

Centromeric instability of chromosomes 1 and 16 with variable immune deficiency: a new syndrome

We describe an extended study of a boy with combined immunodeficiency and centromeric fragility of chromosomes 1 and 16. This case, together with three previously reported cases with similar clinical, immunological and chromosomal features, appears to confirm a specific syndrome of immune deficiency associated with centromeric fragility of chromosomes 1, 9 and 16.

The structural basis for C-banding. A scanning electron microscopy study

The same C-banded human polymorphic chromosomes were observed in the light microscope (LM) and then in the scanning electron microscope (SEM) to investigate the structural changes produced by the C-banding technique. C-banded regions, which stained positively in LM, were highly condensed with tightly packed chromatin fibres, resembling non-banded chromosomes. In striking contrast, adjacent non-C-banded regions were represented by loosely arranged fibres, resembling G-banded chromosomes. The significance of these observations in relation to current theories on the effects of C-banding on chromosome structure is discussed.

Investigation of human chromosome polymorphisms by scanning electron microscopy

Human chromosome polymorphisms were investigated by scanning electron microscopy (SEM). Centromeric heterochromatin was of a constricted morphology. The extent of the C banded region was demarcated by a prominent circumferential groove in G banded chromosomes. Circumferential grooves were observed within the heterochromatin of chromosome 9, and the number of grooves present reflected the size of the region. Three dimensional viewing of satellites and short arms of acrocentric chromosomes, from different angles in the SEM, provided the opportunity for accurate assessment of the size of satellites to be made. Also, small morphological variations were defined in the SEM when definition was uncertain in the light microscope (LM).

Clinical correlations of the 3q21;q26 cytogenetic anomaly. A leukemic or myelodysplastic syndrome with preserved or increased platelet production and lack of response to cytotoxic drug therapy

Three patients presenting with acute leukemic disorder and chromosome 3 rearrangement involving bands q21;q26 are reported, and the literature on chromosome 3q abnormalities is reviewed. All reported patients carrying a paracentric 3q inversion or a translocation 3;3 with breakpoints in q21;q26 had a myelodysplastic or acute leukemic disorder with a normal or elevated platelet count and lack of response to cytotoxic drug therapy. They showed an associated incidence of -7 or 7q- anomalies higher than de novo acute leukemia and appear to constitute a definite subgroup of the leukemic disorders with very poor prognosis. The majority of patients showing other chromosome 3 long arm rearrangements showed evidence of leukemic process, were in blastic crisis, or had been exposed to chemotherapy, exhibiting also a higher incidence of associated -5 or -7 cytogenetic abnormalities than is observed in patients not exposed to toxic agents.

Investigations of chromosomal stability in the Gorlin-Goltz syndrome

Chromosomal studies were carried out on nine patients with the Gorlin-Goltz syndrome using recently developed methods on cultured lymphocytes. In addition, the dermatoglyphics of these patients were examined. No evidence of a characteristic chromosome aberration was found in banded prometaphase-chromosome preparations, nor could increased chromosome breakage be demonstrated in eight of the patients. One proposita showed frequent breaks of Chromosome 1 at p22. Increased chromosome instability in these patients was suggested by higher spontaneous and mitomycin-C-induced sister chromatid exchange rates in patients than in controls. Although the dermatoglyphic findings cannot be regarded as specific for the Gorlin-Goltz syndrome, an increased occurrence of whorl patterns and white lines in patients' fingerprints was noted.

Early replication banding reveals a strongly conserved functional pattern in mammalian chromosomes

One of the best documented autosomal linkage associations in man is on chromosome 1p and in the mouse on chromosome 4. On mitotic chromosomes this genetic homology is shown more clearly by early replication banding (RBG; induced by incorporation of 5'bromodeoxyuridine (BrdU) in the second half of the S phase) than by structural banding (induced on prefixed chromosomes by denaturation, RFA, or trypsin, GTG). To analyse this phenomenon in more detail, 11 chromosomal regions in man and the domestic cat with known genetic homology were compared. In four chromosome pairs RBG and GTG banding show the same degree of homology. In seven chromosome pairs the homology is more pronounced by RBG than by GTG banding. RFA banding does not reveal the same extent of homology as does RBG banding. These results clearly show a difference between the structural banding pattern, RFA and GTG, and the replication banding pattern, RBG. The following conclusions can be drawn: in chromosomal regions with homologous functions the DNA replicates in the same temporal order. Early replication banding (RBG) reveals a functional pattern in these regions which has been more strongly preserved during evolution than the underlying chromosomal DNA. Differences in chromosomal banding are most prominent in the GTG banding pattern, whereas similarities are most apparent in the RBG banding pattern.

Balanced rearrangement of chromosomes 2, 5, and 13 in a family with duplication 5q and fetal loss

We have studied a family in which a mother and daughter (the proposita) had the karyotype 46,XX,ins(2;5),t(5;13). The mother had four spontaneous abortions, a mentally retarded son with duplication (5q), and a daughter who died at 3 months. The proposita had a phenotypically abnormal abortus. Rearrangements involving several chromosomes are very rare. Observations on this family are consistent with the predicted high likelihood of reproductive loss.

[Duplication of the long arm of chromosome 3 (dup 3q) in a newborn infant whose the father is carrier of pericentric inversion of chromosome 9]

The authors report a case of a partial trisomy for the long arm of chromosome 3. The associated morphotypic anomalies are compared with the 31 cases already reported, and allow to further outline a well recognizable morphotype which has similarities with the Brachmann Cornelia de Lange Syndrome. The chromosomal mechanisms which may result in this unbalanced caryotype dup 3 q are discussed, and among them the possible role of a paternal chromosome 9 pericentric inversion, most commonly termed as a normal variant.

New genetics of Burkitt's lymphoma and other non-Hodgkin's lymphomas

Recent progress in cytogenetics and molecular genetics allows striking new insight into Burkitt's lymphoma. In this B cell tumor, the oncogene c-myc located on the long arm of chromosome 8 translocates to one of three locations: adjacent to the immunoglobulin heavy chain gene on chromosome 14, adjacent to the gene for the kappa light chain of immunoglobulin on chromosome 2, or adjacent to the gene for the lambda light chain on chromosome 22. Nucleotide sequence analysis indicates that the translocated c-myc is usually upstream of an immunoglobulin constant region gene, although the exact position varies. In its new location, the oncogene is actively transcribed and may have escaped its normal control mechanisms. It can be no coincidence that this B cell lymphoma is intimately associated with a misadventure in the genetic underpinnings of the major event in B cell differentiation, the assembling of a functional immunoglobulin molecule. Similar genetic catastrophes probably account for the more common B cell lymphomas and could provide the basis of a coherent lymphoma classification.

[Familial translocation t(3;22) detected in a carrier child with mental retardation and other abnormalities]

A case of familial translocation t(3;22) (q21;q13) detected through a boy carrier with various functional and phenotypical alterations is described. The caryotype study (G bands) showed that the mother, one maternal aunt, two maternal uncles, and the brother of the proband were likewise carriers of the same translocation. We discuss the type of segregation and the high familial incidence of the translocation.

A gene regulating the time dependence of alpha-L-fucosidase concentration is closely linked with the structural gene in man

The dependence of the specific activities of human alpha-L-fucosidase and four other lysosomal glycosidases on cell growth was determined in long-term lymphoid cell lines in which the polymorphic forms of alpha-L-fucosidase were identified by isoelectric focusing. In cultured lymphoblasts of Fu-1 phenotype the alpha-L-fucosidase synthesis during cell growth was found to be proportional to the general amount of protein. However, in cells derived from individuals possessing at least one FUCA*2 allele, the amount of enzyme increased progressively during the log-phase of growth, reaching a maximum at the transition to the stationary phase. The maximum increase of enzyme concentration was observed in the mid-log phase of exponential growth. The results may be explained by the existence of a regulatory locus FUCT which maps in close proximity to the structural gene. The FUCT locus which controls the amount of enzyme in the cell appears to be specific for alpha-L-fucosidase.

Telomeric association of chromosomes in B-cell lymphoid leukemia

About 20% of leukemic bone marrow cells from each of two patients with B-cell lymphoid leukemias showed apparent translocations which appeared to be the result of telomeric association. In one patient, whole chromosomes were associated telomere to telomere in pairs; in the other patient, telomeres of whole chromosomes were associated with breakpoints located close to the proximal or distal ends of the heterochromatic band 1q12. Repeated base sequences, particularly (CA)n sequences, are believed to be the basis of telomere pairing, and likewise repeated base sequences of heterochromatin may explain the association of 1qh and telomeres. Telomeric association may be considered as a potential origin of new stable cytogenetic combinations that have a role in oncogene transposition and tumor etiology.

Chromatin of h regions of human chromosomes at high resolution

Segmentation of the secondary constriction region (h) of human chromosomes 1, 9 and 16 is demonstrated by a high resolution banding technique. Based on these staining properties, it is suggested that the composition of the h region in human chromosomes is heterochromatic as well as euchromatic.

The Cd technique identifies a specific structure related to centromeric function

The evidence that the Cd technique identifies the kinetochore was based on the finding that inactive centromeres are C-positive but Cd-negative. The identity between Cd-positivity and centromere function is now confirmed by the reverse procedure: a stable abnormal chromosome is consistently C-negative but Cd-positive at its single centromeric constriction. This demonstrates that the Cd dots are not a relic of C-banding but identify the active centromere.

Interstitial deletion of chromosome 1 (q23-q25). Report of a case

We describe a 3-month-old female with a de novo interstitial deletion of the long arm of chromosome 1 (1q23-25). Clinical features are failure to thrive, psychomotor retardation, cleft lip and palate, short metacarpals, metatarsals and fingers and a severe congenital heart disease. The four previously reported patients with the same deletion share with ours the distinctive pattern of anomalies of the face and limbs; therefore, it seems now possible to delineate a proximal 1 q deletion syndrome.

Ring (13),t(2;6) associated with familial fragile (16)

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Whole arm translocation t(1;13) in an infertile man

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De novo translocation involving chromosomes 2, 8, and 20

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[Multiple chromosome aberrations in 3 generations of a family and Down's syndrome resulting from partial trisomy of chromosome 21 (q21--q22)]

Two balanced translocations (1; 16) (q22; q11) and t(21; 22) (q21; p11), partial inversion of chromosome 9 and variant 16gh + were detected in the family of the child with Down's syndrome. The proband clinical picture was due to trisomy of the distal region of the long arm of chromosome 21 (q21----q22). Proband's karyotype was 46, XY, --22, +der(22), t(21; 22)mat, inv(9). Carriers of variant 16gh+ had a normal phenotype and a normal reproductive function. The relation is discussed of the balanced translocations and C-heterochromatin to the development of following chromosomal aberrations. A probability prediction of the progeny is given. It is advisable to make a prenatal diagnosis of the fetal chromosome set for each subsequent pregnancy.

Contribution of reciprocal translocations to an understanding of chromosome displacement: inferences for studies of spatial order at metaphase

Chromosome displacement was analysed in three different translocations. Two alternative hypotheses were examined: (1) Displacement is determined by the spatial ordering of chromosomes on the metaphase plate. (2) Displacement is a function of the gross physical property of chromosome size and does not reflect ordering. Predicted numbers of displacements were calculated for each chromosome for each of the two hypotheses and these were compared with the observed numbers of displacements using a chi 2 analysis. In the analysis for two of the three translocations, the first hypothesis was rejected whilst the alternative hypothesis was supported by all three analyses. It is concluded that chromosome displacement is a function of chromosome size and does not reflect spatial ordering at metaphase. Furthermore, it is suggested that many studies of apparent ordering at metaphase may merely reflect chromosome displacement. The analysis of displacement rates in all other chromosomes of the complement was undertaken in one of the translocation carriers. This showed no alteration of relative displacement rates.

Involvement of band 3p14 in t(3;8) hereditary renal carcinoma

High resolution prometaphase G-banding analysis was applied to three translocation carriers from the t(3;8) hereditary renal cell carcinoma family. It was clearly illustrated that the chromosomal rearrangement is reciprocal with breakpoints occurring at the subbands 3p14.2 (instead of 3p21) and 8q24.1.

Tandem dup (1p) within the short arm of chromosome 1 in a child with ambiguous genitalia and multiple congenital anomalies

A newborn infant was found to have multiple congenital anomalies including bilateral cleft of lip and palate, intrauterine growth retardation, microcephaly, tetralogy of Fallot, ambiguous external genitalia, and presence of male and female internal genitalia. Chromosome analysis showed a tandem duplication of part of the short arm of chromosome 1, resulting in a dup(1p31----35). The karyotype designation is 46,XY,dir dup(pter----31::p35----p31::p31----qter). The exact nature of the chromosome anomaly was clarified with use of several banding methods.

Cytogenetics of human malignant melanoma and premalignant lesions

Chromosome studies were done on direct preparations, early passage cultures, and/or cell lines derived from melanocytic lesions of 17 patients. There were 5 nevi (3 dysplastic); 1 early primary melanoma (radial growth phase); 1 advanced primary melanoma (vertical growth phase) with multiple metastases; and 10 metastatic lesions. The 5 nevi had normal karyotypes, while each of the tumors had a predominantly abnormal karyotype. The early melanoma was pseudodiploid, including a 6p;22 translocation. Ten of the 11 advanced melanomas had one or more aberrations involving chromosome #1, with 9 having deletions or translocations of lp that involved the proximal segment 1p12----1p22 9 times in 8 lesions. Six advanced tumors had additional material involving 7q, including extra #7s (4 cases) and 7q+ (2 cases). Nine melanomas, including the early tumor, had alterations in chromosome #6. Three had additional copies of 6p (as iso6p or t6p); the others showed no consistent pattern. In one advanced tumor, the primary lesion and 5 metastases (removed seriatim over an 18-month period) had nearly identical karyotypes, indicating the clonal nature of the neoplasm. The nonrandom cytogenetic changes suggest that genes important in melanoma carcinogenesis are located on the proximal portion of 1p, on 7q, and on chromosome #6. More data on early lesions are needed to identify the relation of these various cytogenetic changes to the different stages of malignant melanoma development.

[Heterochromatic regions of human chromosomes 1, 9, 16 and Y and the phenotype]

The relationship between variability of the heterochromatic regions of chromosomes 1, 9, 16, Y and the anthropometric characteristics (the height, the biacromial diameter and weight) was studied in two groups of children; 70 children had embryopathies of unknown etiology and 40 children had the Down syndrome. The positive statistically significant correlation of the C-segments lengths of chromosomes 1, 9, 16, their sum included, and above characteristics was found. The correlation coefficients of Y-chromosome were non-significant. The problems of functional role of the structural heterochromatin and its influence on viability and physical development of the organism are discussed.

De novo direct tandem duplication of the proximal long arm of chromosome 2: 46,XX,dir dup(2)(q11 X 2q14 X 2)

A child is described with a de novo direct duplication of the region 2q11 X 2 leads to 2q14 X 2. She probably represents the first reported case of proximal 2q duplication. The abnormalities included short stature, microcephaly, brachycephaly, depressed nasal bridge, prominent philtrum, congenital glaucoma, and mental retardation.

NOR associations with heterochromatin

Associations between nucleolus organizer regions (NORs) and non-acrocentric chromosomes were scored in 2,800 metaphase spreads from PHA-stimulated lymphocyte cultures (48 h) from 14 individuals. The preparations were both silver stained and C-banded. In order to calculate the expected values for associations, the ratio of heterochromatin length to euchromatin length was established for each subject. Individual C-band lengths and centromeric lengths were also determined. When silver connective (SC) associations with heterochromatin were compared to SC associations with euchromatin, the number of associations with heterochromatin was significantly greater than expected (P less than 0.000001) for each subject. The SC associations were not distributed randomly over the heterochromatin of the non-acrocentrics. Chromosomes 1 and 2 had significantly more than expected. Chromosomes 17, 18, 19, 20, and the Y had fewer than expected. NOR associations with euchromatic segments also showed a nonrandom pattern of distribution.

The level of 6-phosphogluconate dehydrogenase (6-PGD) activity in a patient with 1p terminal deletion suggests that the gene locus is not distal to sub-band p36.3 on chromosome 1

A rare case of chromosome 1p deletion is reported in a mentally retarded male infant with a derived chromosome: 45,XY,-1,-13,tdic(1;13)(1qter----1p36.2::13p11.2----++ +13qter). Parental chromosomes were normal. Since the patient's 6-PGD specific activity was in the normal range, it is probable that he retained both 6-PGD alleles. Consequently, if a dosage affect exists, then the locus for 6-PGD must be proximal to 1p36.3.

Homogeneously staining regions (HSR) in a human malignant melanoma

A case of nodular malignant melanoma (level V of Clark's classification) with homogeneously staining regions (HSR) on the long arm of one chromosome #2 is described. Ultrastructural observation of melanosomic and promelanosomic granules near Golgi's vesicles confirmed the histologic diagnosis. Chromosome analysis was performed on nine metaphases from a bone marrow sample and 76 metaphases from culture of the malignant skin tumor. G-banding revealed the presence of a clone with trisomy #8 and another cell line with the HSR marker. This is the first report of HSR in human melanoma cells. As HSR has been found only in malignant cells, we believe that among the many factors that influence the patients' clinical evolution and poor response to treatment, the genic imbalance is of the utmost importance.

[Polymorphism of the heterochromatic regions of chromosomes 1, 9, 16 and Y and mental retardation]

Polymorphism of the heterochromatic regions (HR) on chromosomes 1, 9, 16 and in three groups of boys at the age of 3 to 14 years was studied. Two groups of boys with olygophrenia of unknown etiology differed by the extent of mental defect, the latter being debility in 50 children, while other 50 children had the profound mental defect. The control group consisted of 50 healthy children. The chromosome sets of all 150 children were normal. The comparative analysis of chromosome polymorphism of C-segments did not reveal any difference between the controls and the children with a slight degree of mental defect. The children with profound mental defect had reduced lengths and variability of C-segments on the chromosomes studied. The problem of relationship between the criteria of patients selection and the results of the study are discussed. The expedience of further investigation of HR polymorphism in patogenetically homogenous groups of children with mental defect is emphasized.

A simple technique for obtaining prometaphase chromosomes from lymphocytes

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Flow karyotype analysis and fluorescence-activated sorting of Burkitt-lymphoma-associated translocation chromosomes

Flow karyotype analysis was performed to assess the feasibility of fluorescence-activated sorting of Burkitt lymphoma (BL)-associated translocation chromosomes. The typical 14q+ chromosome in the t(8;14) and the two "variant translocations", the 2q+ in the t(2;8) and the small 22q- in the t(8;22), could be identified as single peaks within the flow karyotypes of metaphase chromosomes isolated from several different BL-lines for each translocation. The translocation chromosomes could be separated with a high degree of purity and in quantities suitable for biochemical analysis. The same analytical and preparative technique was also successfully applied to the identification and sorting of the Philadelphia (Ph1) chromosome in a 9;22 translocation-carrying CML-derived line and a familial (11;22) translocation.

Localization of c-ras oncogene family on human germ-line chromosomes

The c-ras family is a set of c-onc genes that are highly conserved in vertebrates. The genes in this family are homologous to the transforming genes of Harvey and Kirsten murine sarcoma viruses (v-Ha-ras and v-Ki-ras, respectively). Using an in situ molecular hybridization method, we detected three sites on the human pachytene chromosomes that exhibited significant hybridization to v-Ki-ras and v-Ha-ras probes. These were chromomere positions that corresponded to bands 11p14.1, 12p12.1, and 12q24.2 of somatic chromosomes. The relationship between these chromosomal sites and previously defined members of the human c-ras gene family is discussed. These chromosomal sites are known to be involved in specific chromosome changes in a variety of tumors and in several congenital disorders that predispose to neoplastic disease.

[Polymorphism of the chromosome Q-segments in phenotypically healthy persons of the native population of the Latvian SSR]

Chromosomes of 140 healthy adult individuals from the Latvian population were investigated by the fluorescence method. Data on the polymorphism patterns are presented for chromosomes 3, 4, 13, 14, 15, 21, 22 and Y. No differences were revealed between sexes in the frequency of highly fluorescent segments of autosomes. The frequencies of homozygotes and heterozygotes for certain chromosome segments did not correspond to the Hardy-Weinberg distribution.