Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Origin cell mapping”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15Linked to original sources
PubMed2006

Isolating apparently pure libraries of replication origins from complex genomes.

Because of the complexity of higher eukaryotic genomes and the lack of a reliable autonomously replicating sequence (ARS) assay for isolating potential replicators, the identification of origins has proven to be extremely challenging and time consuming. We have developed a new origin-trapping method based on the partially circular nature of restriction fragments containing replication bubbles and have prepared a library of approximately 1,000 clones from early S phase CHO cells. When 15 randomly selected clones were analyzed by a stringent two-dimensional (2D) gel replicon mapping method, all were shown to correspond to active, early firing origins. Furthermore, most of these appear to derive from broad zones of potential sites, and the five that were analyzed in a time-course study are all inefficient. This bubble-trapping scheme will allow the construction of comprehensive origin libraries from any complex genome so that their natures and distributions vis-a-vis other chromosomal markers can be established.

Animals↗
PubMed1990

Use of fluorescent in situ hybridization to detect chromosomal rearrangements in somatic cell hybrids.

In situ hybridization of hamster/human hybrids with biotinylated human genomic DNA has revealed that human chromosomal DNA can integrate into the hamster genome and is not always cytologically detectable. This finding helps to explain why discordancy can arise in gene mapping by failing to recognize small pieces of foreign DNA in the rodent genome. Fluorescent in situ hybridization allows one to locate these fragments in rodent chromosomes visually and possibly to identify their chromosome of origin.

Animals↗
PubMed2004

Hereditary 'white nails': a genetic and structural study.

BACKGROUND: Hereditary subtotal leuconychia is a rare nail disease. The gene(s) underlying this phenotype is (are) not known. Immunohistochemical and ultrastructural studies of nails are performed infrequently. OBJECTIVES: To perform genetic linkage analysis and to assess ultrastructure and soft/hard keratin expression in hereditary white nails. METHODS: We have analysed microscopically and ultrastructurally the white nails of a patient from a family in which the trait is inherited in an autosomal dominant manner as an isolated symptom. No skin lesions or hair abnormalities could be detected. Genetic linkage studies were performed on DNA samples obtained from several members of the affected family. A longitudinal surgical biopsy of the nail from a great toe was split in two parts. One part was fixed in formalin and processed for histopathology. Another part was further subdivided and embedded either in Epon, following fixation in 2% glutaraldehyde, or in Lowicryl K4M, after fixation in 3% paraformaldehyde. Dewaxed nail sections and Lowicryl ultrathin sections were also stained with various antikeratin antibodies. RESULTS: Genetic linkage studies of the family pointed to the disease gene mapping to the chromosomal 12q13 region. Genes mapping within this chromosomal region include the genes coding for type II (basic) cytokeratins and hard keratins. The nail matrix presented an abnormal hypergranulosis. The upper part of the nail plate, originating from the proximal nail matrix, had a nonhomogeneous lamellar appearance, with numerous intracellular 'lipidic' vacuoles and 'empty' spaces separating keratin filament bundles. These cells were progressively shed at the nail surface. The cell loss was compensated by hyperproliferation of the distal matrix and of the nail bed keratinocytes, with persistent marked parakeratosis and loose arrangement of keratin bundles. The distal matrix and the nail bed contributed equally to formation of the lower plate. This presented the characteristics of a tissue composed of soft keratins. Accordingly, there was virtually no labelling with the Hb1 antibody to a basic hard keratin in the white nail, whereas the labelling with AE3 antibody to all type II keratins and with KL1 recognizing suprabasal soft keratins was normal or even enhanced. CONCLUSIONS: Genetic linkage indicates that the gene defect underlying the leuconychia in the family studied resides on chromosome 12q13. As the type II keratins map within this chromosomal interval, it is possible that a mutation in one of these keratin genes may be a cause of the hereditary leuconychia. The white appearance of nails in this disease seems to be due to an abnormal keratinization of cells originating from the proximal nail matrix, leading to the presence of abundant intracellular vacuoles and to a lesser compactness of keratins.

Chromosome Mapping↗
PubMed1994

Fine mapping of a replication origin of human DNA.

A highly sensitive procedure was developed for the identification of the origin of bidirectional DNA synthesis in single-copy replicons of mammalian cells. The method, which does not require cell synchronization or permeabilization, entails the absolute quantification, by a competitive PCR procedure in newly synthesized DNA samples, of the abundance of neighboring DNA fragments distributed along a given genomic region. This procedure was utilized for mapping the start site of DNA replication in a 13.7-kb region of human chromosome 19 coding for lamin B2, which is replicated immediately after the onset of S phase in HL-60 cells. Within this region, DNA replication initiates in a 474-bp area corresponding to the 3' noncoding end of the lamin B2 gene and the nontranscribed spacer between this gene and the 5' end of another highly transcribed one. This localization was obtained both in aphidicolin-synchronized and in exponentially growing HL-60 cells.

Animals↗
PubMed1999

Early specification of oligodendrocytes in the chick embryonic brain.

Oligodendrocytes are the myelin-forming cells in the central nervous system of vertebrates. In the rodent embryo, these cells have been shown to emerge from restricted territories of the neuroepithelium. However, a comprehensive view of the development of oligodendroglial populations from their ventricular sources remains to be established. As a first step toward this aim, we have examined in vivo the spatiotemporal emergence of oligodendrocytes in the chick embryonic brain. We have detailed the patterns of expression of three early markers of the oligodendroglial lineage: the plp/dm-20 and PDGFRalpha transcripts and the O4-reactive antigen. During embryonic development, these molecules showed a similar segmental pattern of expression. However, plp/dm-20(+) cells were already observed, in the ventricular layer, at E2.5, i.e., 2 days before the appearance of O4(+) and PDGFRalpha(+) cells, suggesting that oligodendrocyte precursors arise nearly simultaneously with neurons. In the chick embryonic brain, the onset of expression of plp/dm-20 appears therefore to be the earliest event indicative of oligodendroglial specification and we propose, based on the expression of plp/dm-20 transcript, a ventricular map of the foci at which oligodendrocytes originate. In addition, we document the precocious segregation, from E5, of plp/dm-20(+) and PDGFRalpha(+) oligodendroglial cells in the subventricular and mantle layers of the brain.

Animals↗
PubMed1994

Locations of postganglionic nerve cells whose axons enter nerves originating from prevertebral ganglia.

Major nerve trunks that supply abdominal viscera contain axons of postganglionic neurons that originate in the coeliac ganglion, superior mesenteric ganglion, inferior mesenteric ganglia, hypogastric nerve ganglia and the sympathetic chain ganglia. Using the retrogradely transported neuronal marker Fast Blue, we mapped the distribution of labelled nerve cells after application of the dye to either the superior coeliac nerves, inferior coeliac nerves, superior mesenteric nerve, colonic nerves or hypogastric nerves. Distinctive patterns of nerve cell locations were associated with each nerve trunk. Within the coeliac ganglion, nerve cells that projected into the superior coeliac nerves were almost exclusively lateral, whilst neurons in the medial part of the coeliac ganglion and in the rostral pole of the superior mesenteric ganglion tended to project into the inferior coeliac nerves. Nerve cells located around the emerging superior mesenteric nerve in the superior mesenteric ganglion contributed the majority of axons to that nerve. Cells in both poles of the inferior mesenteric ganglia contributed the majority of postganglionic axons to the colonic nerves, but some cells in the caudal pole of the superior mesenteric ganglion also projected into the colonic nerves. Postganglionic axons in the hypogastric nerves originated from cells predominantly located in the caudal pole of the inferior mesenteric ganglion; however, cells in the rostral pole of the inferior mesenteric ganglia, the superior mesenteric, coeliac and hypogastric nerve ganglia also contributed some axons. Nerve cells of sympathetic chain ganglia projected into each of the nerve trunks; they were distributed rostro-caudally according to the nerve injected.

Animals↗
PubMed1985

Effects of mutagens on the immunogenicity of murine tumor cells: immunological and biochemical evidence for altered cell surface antigens.

Eb lymphoma cells were subjected to treatment in vitro with the alkylating mutagen N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and then cloned by limiting dilution. When tested in vivo for tumorigenicity in groups of syngeneic DBA/2 mice, 6 from 18 clones were found to be strongly reduced (tum- phenotype). The other clones showed only moderate or no change in tumorigenicity compared to the untreated control. All clones were able to grow in 400-rad-irradiated mice. Mice in which MNNG clones had regressed were able to generate tumor-specific cytolytic T-lymphocytes in vitro. Limiting dilution analysis indicated that 3 of 4 MNNG clones analyzed in detail displayed additional antigenic determinants that were detected by cytolytic T-lymphocytes. These data thus provided evidence for increased immunogenicity of some of the MNNG clones. Membrane proteins of MNNG clones and original Eb cells were compared biochemically after metabolic labeling with [35S]methionine, TX114 solubilization, and electrophoretic separation. Two-dimensional gel maps revealed a general quantitative decrease in the expression of membrane proteins in MNNG clones. In addition, several proteins were only found in MNNG clones but not in untreated cells. Two membrane proteins of molecular weight 22,000 and 38,000 were greatly increased in expression in all MNNG clones but could be detected at a low level in the original Eb cells. MNNG is known to be a strong mutagenic agent, but it can also interfere with DNA methylation and cause transcriptional activation of genes. We suggest that amplified cell surface structures may be the consequence of such transcriptional activation and could be involved in altered immunogenicity.

Animals↗
PubMed1994

A homozygous deletion in a small cell lung cancer cell line involving a 3p21 region with a marked instability in yeast artificial chromosomes.

All types of lung carcinoma are characterized by a high frequency of loss of sequences from the short arm of chromosome 3, the smallest region of overlap containing D3F15S2 in band p21. Here we characterize a 440-kilobase segment from this region, which we found homozygously deleted in one of our small cell lung cancer-derived cell lines. The homozygous deletion maps between UBE1L and ZnF16, just centromeric to D3F15S2. Yeast artificial chromosomes with inserts originating from the deleted region are very unstable and readily lose parts of their insert.

Base Sequence↗
PubMed1990

Amplification by host cell factors of a sequence contained within the herpes simplex virus 1 genome.

We report that a cloned 1620-base-pair (bp) DNA fragment mapping in the BamHI O fragment of herpes simplex virus 1 DNA is amplified after transfection into uninfected cells. The DNA fragment maps entirely within a portion of the open reading frame encoding the large subunit of the viral ribonucleotide reductase and does not contain any of the known lytic origins of viral DNA synthesis. Amplification of this sequence in transfected cells results in accumulation of full-sized Dpn I-resistant plasmids containing the sequence in Hirt extracts of low molecular weight DNA. Subfragments of the 1620-bp fragment were not amplified, whereas larger fragments containing the intact 1620-bp fragment were amplified. The amplification of the fragment in MCF7 cells, which express steroid receptors, was stimulated by the addition of estrogen to the medium. Addition of progesterone, dexamethasone, or testosterone was ineffective. The viral genome therefore contains at least one origin of DNA synthesis capable of supporting replication of viral DNA by cellular factors. The existence of such a host origin of DNA replication in the viral genome was predicted by the hypothesis that viral DNA is amplified by cellular enzymes in sensory neurons harboring latent virus; the link between these sequences and amplification of viral DNA during latency remains to be proven.

Animals↗
PubMed1985

Structural characteristics of Tla products.

Biochemical study of thymus leukemia antigen (TL) from thymocytes of various Tla genotypes and from leukemia cells revealed features that, given present evidence, are peculiar to TL among class I products of the H-2:Qa:Tla region of chromosome 17. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of TL from thymocytes of all TL+ mouse strains, precipitated by anti-TL antiserum or monoclonal antibodies, showed two closely migrating bands of equal intensity in the heavy (H) chain position (45-50,000 mol wt). Comparison of these two bands by two-dimensional isoelectric focusing (2D IEF)-SDS-PAGE and 2D chymotryptic peptide mapping showed no differences indicative of protein dissimilarity. Thus, the two components of the H chain doublet may differ only in a feature of glycosylation that does not affect charge. The two leukemias studied gave only a single band in the H chain position. On 2D peptide mapping and 2D IEF-SDS-PAGE, the patterns for TL of Tlaa and Tlae thymocytes, which are closely related serologically, were broadly similar, but clearly different from the pattern typical of Tlac and Tlad thymocytes. 2D peptide maps of TL from Tlaa thymocytes and Tlaa leukemia cells did not differ. Leukemia cells of Tlab origin (thymocytes TL-) gave 2D peptide and 2D IEF-SDS-PAGE patterns of a third type. With the exception of Tlaa, thymocytes of TL+ mice yielded additional TL products of higher molecular weight than the TL H chain.

Animals↗
PubMed2005

Organization of stem cells and their progeny in human epidermis.

Renewal of epidermis is achieved by an ordered replication of stem cells and transit amplifying cells followed by terminal differentiation. In mouse epidermis, renewal is organized around highly ordered structures termed epidermal proliferative units (EPU), each generated by a single stem cell. It has been difficult to apply these concepts to the human epidermis where the basal layer is undulating and the strata have variable thickness. For example, it is unclear whether stem cells in human epidermis are located at the base of rete ridges or overlying the tip of dermal papilla. Data are available to support both views. To gain a better understanding of EPU organization in human skin, we have genetically marked xenografts of human foreskin with a lentivirus encoding a fluorescent marker protein and have mapped labeled columns of cells over a 28-wk period. By following these columns to their origin in the epidermis we have been able to determine that stem cells are dispersed along the basal compartment. The widths of these columns do vary considerably, with the narrowest originating from cells located in the base of the rete ridge. These findings provide new insights into the dynamics of epidermal renewal in human glabrous skin.

Animals↗
PubMed1995

Spatial distribution of connexin43, the major cardiac gap junction protein, visualizes the cellular network for impulse propagation from sinoatrial node to atrium.

Myocytes are electrically coupled by gap junctions, which are composed of low-resistance intercellular channels. The major cardiac gap junction protein is connexin43 (Cx43). The distribution of Cx43 has been studied by immunofluorescence to visualize the electrical coupling between atrial tissue and sinoatrial node. From modeling studies, this coupling was inferred to be gradual in order to shield the sinoatrial node from the atrial hyperpolarizing influence. The actual Cx43 labeling pattern did not show the expected gradient but instead a rather black and white staining in a striking pattern of strands of cells. We used an immunohistochemical marker (anti-alpha-smooth muscle actin [alpha SMA]) that specifically cross-reacts with guinea pig sinoatrial node cells together with Cx43 antibody to stain previously electrophysiologically mapped sinoatrial nodes. We found that in the guinea pig sinoatrial node the impulse originates in an alpha SMA-positive, virtually Cx43-negative, region (primary pacemaker region). The impulse then travels obliquely upward to the crista terminalis through a region where layers of alpha SMA-positive cells alternate with layers of Cx43-positive SMA-negative cells. The layers of Cx43-positive cells appear to become broader and thicker in the direction of the crista terminalis, whereas the layers of alpha SMA-positive cells become thinner and narrower. Lateral contacts between Cx43- and alpha SMA-positive cells were very sparse and only detected where the Cx43-positive strands ended (the region where alpha SMA-positive cells fill the whole space between endocardium and epicardium, ie, the putative primary pacemaker region). From these results, we conclude that the primary pacemaker is shielded from the hyperpolarizing influence of the atrium by a gradient in coupling brought about by tissue geometric factors rather than by a gradient of gap junction density.

Actins↗
PubMed1995

Proliferation zones in the brain of adult gymnotiform fish: a quantitative mapping study.

Whereas in mammals postnatal neurogenesis, gliogenesis, and angiogenesis appear to be kept at low rates, in fish the capability for the production of new brain cells during adulthood is very pronounced. Many of the newly generated cells originate from germinal layers that maintain their proliferative activity during adulthood. By employing incorporation of the thymidine analogue 5-bromo-2'-deoxyuridine (BrdU) into mitotic active cells, we have quantitatively mapped such proliferation zones in the brain of adult Apteronotus leptorhynchus (Gymnotiformes, Teleostei). In the telencephalon, diencephalon, mesencephalon, and rhombencephalon, the total number of BrdU-labelled cells was low, making up approximately 25% of all mitotic active cells in the brain. Many of these cells were scattered over wide areas. Otherwise, zones of high proliferative activity were typically located at or near the surface of ventricular, paraventricular, and cisternal systems. Approximately 75% of all BrdU-labelled cells found in the brain of adult Apteronotus leptorhynchus were situated in the cerebellum. Zones displaying proliferative activity were restricted to small areas, such as narrow stripes around the midline of corpus cerebelli and valvula cerebelli, the boundary between corpus and valvula, and a large portion of the area covered by the eminentia granularis medialis. Counts indicate that, on average, 100,000 cells, corresponding to approximately 0.2% of the total population of cells in the brain of adult Apteronotus leptorhynchus, are in S-phase within a period of 2 hours. At least part of these newly generated cells is added to the population of already existing cells. This leads to a permanent growth of the brain with increasing size of the fish, a process that appears to slow down only in individuals of relatively advanced age.

Animals↗
PubMed1993

A gene for Hirschsprung disease maps to the proximal long arm of chromosome 10.

Hirschsprung disease (HSCR) is a frequent congenital disorder (1 in 5,000 newborns) of unknown origin characterized by the absence of parasympathetic intrinsic ganglion cells of the hindgut. Taking advantage of a proximal deletion of chromosome 10q (del 10q11.2-q21.2) in a patient with total colonic aganglionosis, and of a high-density genetic map of microsatellite DNA markers, we performed genetic linkage analysis in 15 non-syndromic long-segment and short-segment HSCR families. Multipoint linkage analysis indicated that the most likely location for a HSCR locus is between loci D10S208 and D10S196, suggesting that a dominant gene for HSCR maps to 10q11.2, a region to which other neural crest defects have been mapped.

Base Sequence↗
PubMed1997

Changes in the tonotopic map of the dorsal cochlear nucleus in hamsters with hair cell loss and radial nerve bundle degeneration.

Hamsters were exposed to an intense tone (10 kHz) at levels and durations sufficient to cause hair cell loss and radial nerve bundle degeneration. A previous study reported changes in the tonotopic map of the dorsal cochlear nucleus (DCN) in hamsters with tone-induced stereocilia loss. Such changes appear similar to those observed by others in the auditory nerve following acoustic trauma, and suggest that the map alterations have a peripheral origin. However, the potential for tonotopic map reorganization after more severe lesions involving cellular degeneration in the cochlea has not yet been determined. The purpose of the present study was to determine how the tonotopic map of the DCN appears in animals with severe cochlear injury involving hair cell loss and radial nerve bundle degeneration. Neural population thresholds and tonotopic organization were mapped over the surface of the DCN in normal unexposed animals and those showing tone-induced lesions. The results indicate that cochlear lesions characterized mainly by radial bundle degeneration in a restricted portion of the organ of Corti cause changes in a corresponding region of the tonotopic map which reflect primarily changes in the shape and thresholds of neural tuning curves. In many cases the center of the lesion was represented in the DCN as a distinct characteristic frequency (CF) gap in the tonotopic map in which responses were either extremely weak or absent. In almost all cases the map area representing the center of the lesion was bordered by an expanded region of near-constant CF, a feature superficially suggestive of map reorganization (i.e., plasticity). However, these expanded map areas had abnormal tip thresholds and showed other features suggesting that their CFs had been shifted downward by distortion and deterioration of their original tips. Such changes in neural tuning following tone-induced loss of anatomical input to the central auditory pathway are similar to those observed in our previous study and by others in the auditory nerve following less severe acoustic trauma, and thus would seem to have a peripheral origin. Thus, changes in the DCN tonotopic map can be explained by peripheral modifications and do not seem to involve plastic changes (i.e., reorganization).

Acoustic Stimulation↗
PubMed1994

Positioning of cell growth and division after osmotic stress requires a MAP kinase pathway.

The yeast Saccharomyces cerevisiae has a genetic program for selecting and assembling a bud site on the cell cortex. Yeast cells confine their growth to the emerging bud, a process directed by cortical patches of actin filaments within the bud. We have investigated how cells regulate budding in response to osmotic stress, focusing on the role of the high osmolarity glycerol response (HOG) pathway in mediating this regulation. An increase in external osmolarity induces a growth arrest in which actin filaments are lost from the bud. This is followed by a recovery phase in which actin filaments return to their original locations and growth of the original bud resumes. After recovery from osmotic stress, haploid cells retain an axial pattern of bud site selection while diploids change their bipolar budding pattern to an increased bias for forming a bud on the opposite side of the cell from the previous bud site. Mutants lacking the mitogen-activated protein (MAP) kinase encoded by HOG1 or the MAP kinase kinase encoded by PBS2 (previously HOG4) show a similar growth arrest after osmotic stress. However, in the recovery phase, the mutant cells (a) do not restart growth of the original bud but rather start a new bud, (b) fail to restore actin filaments to the original bud but move them to the new one, and (c) show a more random budding pattern. These defects are elicited by an increase in osmolarity and not by other environmental stresses (e.g., heat shock or change in carbon source) that also cause a temporary growth arrest and shift in actin distribution. Thus, the HOG pathway is required for repositioning of the actin cytoskeleton and the normal spatial patterns of cell growth after recovery from osmotic stress.

Actins↗
PubMed2000

Paternal meiotic origin of der(21;21)(q10;q10) mosaicism [46,XX/46, XX,der(21;21)(q10;q10),+21] in a girl with mild Down syndrome.

Mosaicism for a derivative 21, der(21;21)(q10;q10), is a rare chromosomal abnormality. Since a normal cell line is present, mitotic origin is considered. Chromosome examination of a female with developmental delay and dysmorphic features compatible with mosaic trisomy 21 revealed a normal cell line and a second cell line with a der(21;21)(q10;q10) [46,XX/46,XX,der(21;21)(q10;q10),+21]. Molecular investigation with a panel of highly polymorphic microsatellites mapping to chromosome 21 demonstrated three different alleles, two of paternal and one of maternal origin. Therefore, either formation of the der(21;21)(q10;q10) during paternal meiosis with subsequent loss of the der(21;21)(q10;q10) and mitotic reduplication of the maternal homologue in the normal cell line, or more likely a zygote with paternally derived trisomy 21 and subsequent mitotic formation of the der(21;21)(q10;q10) have to be considered. This case again shows that mammalian chromosome aberrations may have a more complex mechanism of formation than was previously thought.

Age Determination by Skeleton↗
PubMed1979

Evolution of multiple genome mutations during long-term persistent infection by vesicular stomatitis virus.

Persistent infection of BHK21 cells was established with cloned vesicular somatitis virus plus purified Dl particles and maintained in vitro for over 5 years. After 1 year of persistence, the infectious virus RNA genome had evolved several oligonucleotide map changes, and numerous changes had accumulated by 3.5 years. Additional evolution occurred by the fourth year and continued until the fifth year. In contrast, repeated passage of virus in acute infections of several cell types in vitro or in vivo did not lead to detectable oligonucleotide map changes. The short Dl particle originally used to co-infect with infectious virus in establishing persistent infection has been displaced by an ever present and constantly changing population of other Dl particles of differing sizes and radically differing oligonucleotide maps. We conclude that the genomes of both infectious VSV and its Dl particles undergo continuous evolutionary change during years of persistence. In the infectious virus, these changes involve hundreds of mutations which are usually expressed as poorly replicating, temperature-sensitive, small plaque mutants. These are stable mutants which do not revert to wild-type when passaged repeatedly in acute infections at 37 or 33 degrees C. It appears that the sequestered intracellular environment of persistently infected cells favors rapid and continuous virus evolution.

Animals↗