ISSN:1424-8581    

DOI:10.1159/000131426

出版商:S. Karger AG    

年代:1980

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000131427

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The implantation intraperitoneally of in vitro cell lines of the SEWA mouse ascites tumor into syngeneic mice and into allogeneic thymusless nude mice stimulated mitotic activity in the host component of the ascites cell population. The mitoses were found almost exclusively during the first month after the change in environment, while the tumor cells gradually readapted to in vivo growth. Normal mitoses appeared immediately after the transfer in vivo, reached a maximum at days 10 to 20, then decreased in frequency and disappeared completely after day 33. At that time, the tumor cells had recovered viability and started growing with full vigor. The ascites samples in which normal cells were undergoing mitotic division often contained a low proportion of tumor cells and a high proportion of small inflammatory cells. The chromosomes of the normal mitoses differed from those of the tumor mitoses by being smaller and more crowded. Their relative uniformity in type was also accentuated by the fact that they were all characterized by a low but ubiquitous incidence of chromatid breaks. These features suggested that the normal mitoses belonged to the lymphocytic population and represented a defense mechanism of the host towards the tumor. Since normal mitoses were especially frequent in the ascites cell population of the thymusless mice, it may be speculated that T-lymphocytes were not the main target cells for the mitotic induction.

ISSN:1424-8581    

DOI:10.1159/000131428

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The chromosome set of the lesser kudu, Tragelaphus imberbis, consists of 38 elements in both sexes. In contrast to most other members of the bovid subfamily Tragelaphinae, both the X and the Y chromosomes are compound, having fused with identical autosomes from ancestors presumed to have higher chromosome numbers. From a comparison of the unusual sex chromosomal rearrangements that have occurred in this family, a hypothetical lineage has been derived. This family tree and the details of various banding studies in the lesser kudu are described.

ISSN:1424-8581    

DOI:10.1159/000131429

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

To investigate the chromosomal sites of integration of the herpes simplex virus type 1 (HSV-1) thymidine kinase (TK) gene in HSV-1-transformed human HeLa(BU25)/ KOS 8–1 cells, the biochemically transformed cells were fused with TK-negative mouse LM(TK-) cells, and human-mouse somatic cell hybrid lines (LH81) were isolated using a HATG-ouabain selection system. The presence of HSV-1 TK activity in the hybrid lines was verified by disc polyacrylamide gel electrophoresis (PAGE) and by enzyme neutralization with type-specific rabbit anti-HSV-1 TK immunoglobulin. Karyotype analyses of several somatic cell hybrid clones using G-banding, Hoechst 33258 staining, and combined G-banding and Hoechst staining demonstrated that they retained only a few human chromosomes. A marker chromosome, M7, consisting of a chromosome 17 translocated to the short arm of 3, occurred in 25 of the 28 metaphases examined. Also, chromosomes 8 and X were found in a minority of metaphases. Isozyme analyses showed that all 19 hybrid clones analyzed expressed human aminoacylase-1 (ACYl) and esterase D (ESD), markers for 3 and 13, respectively. Back-selection of somatic cell hybrid clones with 5-bromodeoxyuridine resulted in the isolation of several subclones lacking HSV-1 TK activity, human ACYl, human ESD, and the human chromosomes. These experiments suggest that the HSV-1 TKgene is associated with either M7 or a segment of 13, or both, in biochemically transformed HeLa(BU25)/KOS 8–1 cells. These experiments also permit localization of the ACYl structural gene to the pter→p12 region

ISSN:1424-8581    

DOI:10.1159/000131430

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

Cytological preparations of testes from squirrels belonging to the genus Ammospermophilus exhibit meiotic peculiarities specifically associated with constitutive heterochromatin.

ISSN:1424-8581    

DOI:10.1159/000131431

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The effects of cyclophosphamide and three of its known metabolites (nitrogen mustard, acrolein, and nor-nitrogen mustard on chromosome breakage and sister chromatid exchange (SCE) were analyzed in vitro with and without the presence of a metabolic activating system (liver S9). We confirmed that cyclophosphamide induced chromosome breakage and SCE only in the presence of S9. After metabolism, cyclophosphamide was more active than the other agents in inducing SCE. Thus, the agent(s) directly responsible for this induction of a high SCE rate was not analyzed in this study. On the other hand, acrolein was most toxic to cell proliferation and most active in inducing chromosome breakage. The cytogenetic toxicity of these agents in comparison with their mutagenic and therapeutic activities is discussed.

ISSN:1424-8581    

DOI:10.1159/000131432

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

Small lymphocytes differentiate into functionally active blast cells in vitro upon stimulation with such mitogens as phytohemagglutinin and sodium periodate. If stimulated lymphocytes are subsequently treated with the nucleic acid intercalating dye ethidium bromide, electron-dense complexes containing nucleic acid are formed in mitochondria, protein synthesis in mitochondria is inhibited, and lymphoblast division ceases. Formation of complexes and the development of morphologically abnormal mitochondria provide ultrastructural evidence of mitochondrial protein inhibition and serve as markers for mitogen-responsive lymphocytes. The formation of these abnormalities in all mitochondria of treated megakaryocytes and 22% of mitochondria in platelets indicates that platelets contain functional nucleic acid and that the induced structural changes may be occurring in a less-differentiated (i.e., younger) subpopulation of circulating platelets.

ISSN:1424-8581    

DOI:10.1159/000131433

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

HeLa S3 cells were cloned, recloned, and then selected for growth in the presence of increasing concentrations of bromodeoxyuridine. Cultures of these cloned thymidine kinase minus (TK-) cells were found to harbor mycoplasma which sedimented with mitochondria in sucrose density step gradients. Examination of mitochondrial DNA (mitDNA) components by restriction enzyme analysis and electron microscopy revealed no gross alterations in size, sequence arrangements, or replicative forms compared with mitDNA of HeLa S3 cells. Restriction enzyme cleavage sites for BamHl (one site), PstI (two sites) and HpaI (three sites) were mapped on this genome relative to the three cleavage sites for each of EcoRI and HindIII, respectively. Analysis of topological complexity revealed similar frequencies of catenated mitDNA molecules in both cloned TK– (22.5 ± 1.5% of mass) and HeLa S3 cells (25.6 ± 1.5% of mass). Unicircular dimers comprise 6.7 ± 0.9% of the mitDNA mass in cloned TK– cells but were not detected in HeLa S3 mitDNA. Examination of the mycoplasmal contaminant of mitochondrial DNA after digestion with various restriction enzymes and agarose gel electrophoresis revealed that most of the DNA was distributed in discretely sized fragments in patterns that can probably be used to unambiguously identify and classify the or

ISSN:1424-8581    

DOI:10.1159/000131434

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The meiotic behavior of silver-stained X and Y chromosomes of the Virginia opossum, Didelphis virginiana, and the southern pygmy mouse, Baiomys musculus, was studied by light microscopy. While the sex chromosomes of these two species differ in both size and morphology, their meiotic behavior is very similar. In both species, a typical sex vesicle is formed during pachytene, but unlike most other mammalian species thus far studied, a synaptonemal complex does not form between the X and Y chromosomes. During pachytene, variable modes of association of the ends of the sex chromosomes (both heterologous and autologous) are sometimes observed. During diplotene, diakinesis, and metaphase I, the X and Y rarely appear to be associated. In some pachytene nuclei of B. musculus, the single axis of the biarmed X chromosome folds back upon itself, and the telomeres form a close association. While synaptic pairing segments of the sex chromosomes of the Virginia opossum may be displaced by telomeric heterochromatin on the X, true pairing regions between the X and Y of the pygmy mouse may be lacking.

ISSN:1424-8581    

DOI:10.1159/000131435

出版商:S. Karger AG    

年代:1980

数据来源: Karger