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At least 883 records · Page 49Linked to original sources
PubMed2006

Focal adhesions are hotspots for keratin filament precursor formation.

Recent studies showed that keratin filament (KF) formation originates primarily from sites close to the actin-rich cell cortex. To further characterize these sites, we performed multicolor fluorescence imaging of living cells and found drastically increased KF assembly in regions of elevated actin turnover, i.e., in lamellipodia. Abundant KF precursors (KFPs) appeared within these areas at the distal tips of actin stress fibers, moving alongside the stress fibers until their integration into the peripheral KF network. The earliest KFPs were detected next to actin-anchoring focal adhesions (FAs) and were only seen after the establishment of FAs in emerging lamellipodia. Tight spatiotemporal coupling of FAs and KFP formation were not restricted to epithelial cells, but also occurred in nonepithelial cells and cells producing mutant keratins. Finally, interference with FA formation by talin short hairpin RNA led to KFP depletion. Collectively, our results support a major regulatory function of FAs for KF assembly, thereby providing the basis for coordinated shaping of the entire cytoskeleton during cell relocation and rearrangement.

Actins↗
PubMed1990

B cells are required for induction of T cell abnormalities in a murine retrovirus-induced immunodeficiency syndrome.

The role of B cells in induction of phenotypic and functional abnormalities of T cells in a murine retrovirus-induced immunodeficiency syndrome, MAIDS, was evaluated in mice depleted of mature B cells from birth with anti-IgM antibodies (mu-suppressed) and infected at 4 wk of age. Multicolor FACS analyses of CD4+ T cell subsets showed that development of phenotypic abnormalities of these cells at 9 wk after infection was completely inhibited by mu-suppression. Furthermore, induction of impaired proliferative responses to Con A and alloantigens and CTL responses to alloantigens was fully blocked in antibody-treated animals. The extent of virus replication was comparable in spleens of untreated and mu-suppressed mice. Retroviral induction of T cell dysfunction in MAIDS is thus dependent on the presence of B cells, and high level virus expression in mice without B cells has little or no effect on T cell function.

Animals↗
PubMed2001

Isolation and characterization of dermal lymphatic and blood endothelial cells reveal stable and functionally specialized cell lineages.

A plexus of lymphatic vessels guides interstitial fluid, passenger leukocytes, and tumor cells toward regional lymph nodes. Microvascular endothelial cells (ECs) of lymph channels (LECs) are difficult to distinguish from those of blood vessels (BECs) because both express a similar set of markers, such as CD31, CD34, podocalyxin, von Willebrand factor (vWF), etc. Analysis of the specific properties of LECs was hampered so far by lack of tools to isolate LECs. Recently, the 38-kD mucoprotein podoplanin was found to be expressed by microvascular LECs but not BECs in vivo. Here we isolated for the first time podoplanin(+) LECs and podoplanin(-) BECs from dermal cell suspensions by multicolor flow cytometry. Both EC types were propagated and stably expressed VE-cadherin, CD31, and vWF. Molecules selectively displayed by LECs in vivo, i.e., podoplanin, the hyaluronate receptor LYVE-1, and the vascular endothelial cell growth factor (VEGF)-C receptor, fms-like tyrosine kinase 4 (Flt-4)/VEGFR-3, were strongly expressed by expanded LECs, but not BECs. Conversely, BECs but not LECs expressed VEGF-C. LECs as well as BECs formed junctional contacts with similar molecular composition and ultrastructural features. Nevertheless, the two EC types assembled in vitro in vascular tubes in a strictly homotypic fashion. This EC specialization extends to the secretion of biologically relevant chemotactic factors: LECs, but not BECs, constitutively secrete the CC chemokine receptor (CCR)7 ligand secondary lymphoid tissue chemokine (SLC)/CCL21 at their basal side, while both subsets, upon activation, release macrophage inflammatory protein (MIP)-3alpha/CCL20 apically. These results demonstrate that LECs and BECs constitute stable and specialized EC lineages equipped with the potential to navigate leukocytes and, perhaps also, tumor cells into and out of the tissues.

Adult↗
PubMed1998

From amplification to gene in thyroid cancer: a high-resolution mapped bacterial-artificial-chromosome resource for cancer chromosome aberrations guides gene discovery after comparative genome hybridization.

Chromosome rearrangements associated with neoplasms provide a rich resource for definition of the pathways of tumorigenesis. The power of comparative genome hybridization (CGH) to identify novel genes depends on the existence of suitable markers, which are lacking throughout most of the genome. We now report a general approach that translates CGH data into higher-resolution genomic-clone data that are then used to define the genes located in aneuploid regions. We used CGH to study 33 thyroid-tumor DNAs and two tumor-cell-line DNAs. The results revealed amplifications of chromosome band 2p21, with less-intense amplification on 2p13, 19q13.1, and 1p36 and with least-intense amplification on 1p34, 1q42, 5q31, 5q33-34, 9q32-34, and 14q32. To define the 2p21 region amplified, a dense array of 373 FISH-mapped chromosome 2 bacterial artificial chromosomes (BACs) was constructed, and 87 of these were hybridized to a tumor-cell line. Four BACs carried genomic DNA that was amplified in these cells. The maximum amplified region was narrowed to 3-6 Mb by multicolor FISH with the flanking BACs, and the minimum amplicon size was defined by a contig of 420 kb. Sequence analysis of the amplified BAC 1D9 revealed a fragment of the gene, encoding protein kinase C epsilon (PKCepsilon), that was then shown to be amplified and rearranged in tumor cells. In summary, CGH combined with a dense mapped resource of BACs and large-scale sequencing has led directly to the definition of PKCepsilon as a previously unmapped candidate gene involved in thyroid tumorigenesis.

Adenocarcinoma, Follicular↗
PubMed1998

Chromosome 21 disomy in the spermatozoa of the fathers of children with trisomy 21, in a population with a high prevalence of Down syndrome: increased incidence in cases of paternal origin.

Between April 1991 and December 1994, epidemiological studies detected a population with a high prevalence of Down syndrome in El Vallès, Spain. Parallel double studies were carried out to determine the parental and the meiotic origins of the trisomy 21, by use of DNA polymorphisms, and to establish the incidence of disomy 21 in the spermatozoa of the fathers of affected children, by use of multicolor FISH. Results show that the overall incidence of chromosome 21 disomy in the fathers of affected children was not significantly different from that in the control population (0.31% vs. 0.37%). However, analysis of individual data demonstrates that two cases (DP-4 and DP-5) with significant increases of disomy 21 (0. 75% and 0.78% vs. 0.37%) correspond to the fathers of the two individuals with Down syndrome of paternal origin. DP-5 also had a significant increase of sex-chromosome disomies (0.69% vs. 0.37%) and of diploid spermatozoa (1.13% vs. 0.24%).

Chromosome Aberrations↗
PubMed1999

Multiplex-FISH for pre- and postnatal diagnostic applications.

For >3 decades, Giemsa banding of metaphase chromosomes has been the standard karyotypic analysis for pre- and postnatal diagnostic applications. However, marker chromosomes or structural abnormalities are often encountered that cannot be deciphered by G-banding alone. Here we describe the use of multiplex-FISH (M-FISH), which allows the visualization of the 22 human autosomes and the 2 sex chromosomes, in 24 different colors. By M-FISH, the euchromatin in marker chromosomes could be readily identified. In cases of structural abnormalities, M-FISH identified translocations and insertions or demonstrated that the rearranged chromosome did not contain DNA material from another chromosome. In these cases, deleted or duplicated regions were discerned either by chromosome-specific multicolor bar codes or by comparative genomic hybridization. In addition, M-FISH was able to identify cryptic abnormalities in patients with a normal G-karyotype. In summary, M-FISH is a reliable tool for diagnostic applications, and results can be obtained in </=24 h. When M-FISH is combined with G-banding analysis, maximum cytogenetic information is provided.

Chromatin↗
PubMed2000

Analysis of aneuploidy frequencies in sperm from patients with hereditary nonpolyposis colon cancer and an hMSH2 mutation.

Hereditary nonpolyposis colon cancer (HNPCC) has been shown to be caused by mutations in the mismatch repair genes hMSH2, hMLH1, hPMS1, and hPMS2. Recent evidence has demonstrated that mutations in mismatch repair genes disrupt meiosis in mice. A large HNPCC kindred in Newfoundland, Canada, has an hMSH2 mutation-an A-->T transversion at the +3 position of the splice-donor site of exon 5. We have studied sperm from men with this hMSH2 mutation, since it is possible that mismatch repair mutations in humans might also have an effect on meiosis and normal segregation of chromosomes. The frequencies of aneuploid and diploid sperm were determined in 10 men with the hMSH2 mutation, by use of multicolor FISH analysis for chromosomes 13, 21, X, and Y. A minimum of 10,000 sperm per man was studied per chromosome probe. Control individuals consisted of men in the same kindred with HNPCC who did not carry the mutation and of other normal men from Newfoundland. A total of 321,663 sperm were analyzed: 200,905 sperm were from men carrying the hMSH2 mutation and 120,758 sperm were from control men. There was a significantly increased frequency of disomy 13, disomy 21, XX, and diploidy in mutation carriers compared with control men. These results suggest that the hMSH2 mutation may affect meiosis in humans.

Adult↗
PubMed2000

An optimized probe set for the detection of small interchromosomal aberrations by use of 24-color FISH.

The rapid spread of the use of new 24-color karyotyping techniques has preceded their standardization. This is best documented by the fact that the exact resolution limits have not yet been defined. Indeed, it is shown here that a substantial proportion of interchromosomal aberrations will be missed by all multicolor karyotyping systems currently in use. We demonstrate that both the sensitivity and the specificity of 24-color karyotyping critically depend on the fluorochrome composition of chromosomes involved in an interchromosomal rearrangement. As a solution, we introduce a conceptual change in probe labeling. Seven-fluorochrome sets that overcome many of the current limitations are described, and examples of their applications are shown. The criteria presented here for an optimized probe-set design and for the estimation of resolution limits should have important consequences for pre- and postnatal diagnostics and for research applications.

Chromosome Aberrations↗
PubMed2000

Comparing the Evolution of the Galaxy Disk Sizes with Cold Dark Matter Models: The Hubble Deep Field.

The intrinsic sizes of the field galaxies with I</=26 in the Hubble and ESO New Technology Telescope (NTT) Deep Fields are shown as a function of their redshifts and absolute magnitudes using photometric redshifts derived from the multicolor catalogs and are compared with the cold dark matter (CDM) predictions. Extending to the lower luminosities and to the higher z that our previous analysis performed on the NTT field alone, we find the distribution of the galaxy disk sizes at different cosmic epochs is within the range predicted by typical CDM models. However, the observed size distribution of faint (MB>-19) galaxies is skewed with respect to the CDM predictions, and an excess of small-size disks (Rd<2 kpc) is already present at z approximately 0.5. The excess persists up to z approximately 3 and involves brighter galaxies. Such an excess may be reduced if luminosity-dependent effects, like starburst activity in interacting galaxies, are included in the physical mechanisms governing the star formation history in CDM models.

Journal Article↗
PubMed2000

Discovery of a Color-selected Quasar at z = 5.50.

We present observations of RD J030117+002025, a quasar at z=5.50 discovered from deep, multicolor, ground-based observations covering 74 arcmin2. This is the most distant quasar or active galaxy currently known. The object was targeted as an R-band dropout, with RAB>26.3 (3 sigma limit in a 3&arcsec; diameter region), IAB=23.8, and zAB=23.4. The Keck/Low-Resolution Imaging Spectrometer spectrum shows broad Lyalpha/N v lambda1240 emission and sharp absorption decrements from the highly redshifted hydrogen forests. The fractional continuum depression due to the Lyalpha forest is DA=0.90. RD J030117+002025 is the least luminous high-redshift quasar known (MB approximately -22.7).

Journal Article↗
PubMed2001

Frequency of XY sperm increases with age in fathers of boys with Klinefelter syndrome.

With increasing availability of drugs for impotence and advanced reproductive technologies for the treatment of subfertility, more men are fathering children at advanced ages. We conducted a study of the chromosomal content of sperm of healthy men aged 24-57 years to (a) determine whether father's age was associated with increasing frequencies of aneuploid sperm including XY, disomy X, disomy Y, disomy 21, and sperm diploidy, and (b) examine the association between the frequencies of disomy 21 and sex-chromosomal aneuploidies. The study group consisted of 38 fathers of boys with Klinefelter syndrome (47, XXY) recruited nationwide, and sperm aneuploidy was assessed using multicolor X-Y-21 sperm FISH ( approximately 10,000 sperm per donor). Paternal age was significantly correlated with the sex ratio of sperm (Y/X; P=.006) and with the frequency of XY sperm (P=.02), with a clear trend with age by decades (P<.006). Compared with fathers in their 20s (who had an average frequency of 7.5 XY sperm per 10,000), the frequencies of XY sperm were 10% higher among fathers in their 30s, 31% higher among those in their 40s, and 160% higher among those in their 50s (95% CI 69%-300%). However, there was no evidence for age effects on frequencies of sperm carrying nullisomy sex; disomies X, Y, or 21; or meiosis I or II diploidies. The frequencies of disomy 21 sperm were significantly associated with sex-chromosomal aneuploidy (P=.04)-in particular, with disomy X (P=.004), but disomy 21 sperm did not preferentially carry either sex chromosome. These findings suggest that older fathers produce higher frequencies of XY sperm, which may place them at higher risk of fathering boys with Klinefelter syndrome, and that age effects on sperm aneuploidy are chromosome specific.

Adult↗
PubMed2002

Stable variants of sperm aneuploidy among healthy men show associations between germinal and somatic aneuploidy.

Repeated semen specimens from healthy men were analyzed by sperm fluorescence in situ hybridization (FISH), to identify men who consistently produced elevated frequencies of aneuploid sperm and to determine whether men who were identified as stable variants of sperm aneuploidy also exhibited higher frequencies of aneuploidy in their peripheral blood lymphocytes. Seven semen specimens were provided by each of 15 men over a 2-year period and were evaluated by the X-Y-8 multicolor sperm FISH method (i.e., approximately 1,050,000 sperm were analyzed from 105 specimens). Three men were identified as stable aneuploidy variants producing significantly higher frequencies of XY, disomy X, disomy Y, disomy 8, and/or diploid sperm over time. In addition, one man and three men were identified as sperm-morphology and sperm-motility variants, respectively. Strong correlations were found between the frequencies of sperm with autosomal and sex-chromosome aneuploidies and between the two types of meiosis II diploidy; but not between sperm aneuploidy and semen quality. A significant association was found between the frequencies of sex-chromosome aneuploidies in sperm and lymphocytes in a subset of 10 men (r2=0.67, P=.004), especially between XY sperm and sex-chromosome aneuploidy in lymphocytes (r2=0.70, P=.003). These findings suggest that certain apparently healthy men can produce significantly higher frequencies of both aneuploid sperm and lymphocytes. Serious long-term somatic and reproductive health consequences may include increased risks of aneuploidy-related somatic diseases and of having children with paternally transmitted aneuploidies, such as Klinefelter, Turner, triple-X, and XYY syndromes.

Adult↗
PubMed2002

The DNA-based structure of human chromosome 5 in interphase.

In contrast to those of metaphase chromosomes, the shape, length, and architecture of human interphase chromosomes are not well understood. This is mainly due to technical problems in the visualization of interphase chromosomes in total and of their substructures. We analyzed the structure of chromosomes in interphase nuclei through use of high-resolution multicolor banding (MCB), which paints the total shape of chromosomes and creates a DNA-mediated, chromosome-region-specific, pseudocolored banding pattern at high resolution. A microdissection-derived human chromosome 5-specific MCB probe mixture was hybridized to human lymphocyte interphase nuclei harvested for routine chromosome analysis, as well as to interphase nuclei from HeLa cells arrested at different phases of the cell cycle. The length of the axis of interphase chromosome 5 was determined, and the shape and MCB pattern were compared with those of metaphase chromosomes. We show that, in lymphocytes, the length of the axis of interphase chromosome 5 is comparable to that of a metaphase chromosome at 600-band resolution. Consequently, the concept of chromosome condensation during mitosis has to be reassessed. In addition, chromosome 5 in interphase is not as straight as metaphase chromosomes, being bent and/or folded. The shape and banding pattern of interphase chromosome 5 of lymphocytes and HeLa cells are similar to those of the corresponding metaphase chromosomes at all stages of the cell cycle. The MCB pattern also allows the detection and characterization of chromosome aberrations. This may be of fundamental importance in establishing chromosome analyses in nondividing cells.

Cell Cycle↗
PubMed2002

Male mouse recombination maps for each autosome identified by chromosome painting.

Linkage maps constructed from genetic analysis of gene order and crossover frequency provide few clues to the basis of genomewide distribution of meiotic recombination, such as chromosome structure, that influences meiotic recombination. To bridge this gap, we have generated the first cytological recombination map that identifies individual autosomes in the male mouse. We prepared meiotic chromosome (synaptonemal complex [SC]) spreads from 110 mouse spermatocytes, identified each autosome by multicolor fluorescence in situ hybridization of chromosome-specific DNA libraries, and mapped >2,000 sites of recombination along individual autosomes, using immunolocalization of MLH1, a mismatch repair protein that marks crossover sites. We show that SC length is strongly correlated with crossover frequency and distribution. Although the length of most SCs corresponds to that predicted from their mitotic chromosome length rank, several SCs are longer or shorter than expected, with corresponding increases and decreases in MLH1 frequency. Although all bivalents share certain general recombination features, such as few crossovers near the centromeres and a high rate of distal recombination, individual bivalents have unique patterns of crossover distribution along their length. In addition to SC length, other, as-yet-unidentified, factors influence crossover distribution leading to hot regions on individual chromosomes, with recombination frequencies as much as six times higher than average, as well as cold spots with no recombination. By reprobing the SC spreads with genetically mapped BACs, we demonstrate a robust strategy for integrating genetic linkage and physical contig maps with mitotic and meiotic chromosome structure.

Adaptor Proteins, Signal Transducing↗
PubMed2004

Human male recombination maps for individual chromosomes.

Meiotic recombination is essential for the segregation of chromosomes and the formation of normal haploid gametes, yet we know very little about the meiotic process in humans. We present the first (to our knowledge) recombination maps for every autosome in the human male obtained by new immunofluorescence techniques followed by centromere-specific multicolor fluorescence in situ hybridization in human spermatocytes. The mean frequency of autosomal recombination foci was 49.8+/-4.3, corresponding to a genetic length of 2,490 cM. All autosomal bivalents had at least one recombination focus. In contrast, the XY bivalent had a recombination focus in 73% of nuclei, suggesting that a relatively large proportion of spermatocytes may be at risk for nondisjunction of the XY bivalent or elimination by meiotic arrest. There was a very strong correlation between mean length of the synaptonemal complex (SC) and the number of recombination foci per SC. Each bivalent presented a distinct distribution of recombination foci, but in general, foci were near the distal parts of the chromosome, with repression of foci near the centromere. The position of recombination foci demonstrated positive interference, but, in rare instances, foci were very close to one another.

Chromosome Mapping↗
PubMed1997

Simultaneous, multilocus FISH analysis for detection of microdeletions in the diagnostic evaluation of developmental delay and mental retardation.

Many microdeletion and contiguous gene-deletion syndromes include mental retardation as a clinical feature. We have developed MultiFISH, a FISH assay using several probes to simultaneously screen for multiple microdeletion syndromes in patients who present with unexplained devleopmental delay and/or mental retardation. This screening tool can be used to determine whether a particular microdeletion syndrome is involved in the etiology of these clinical phenotypes. In this pilot study we combined probes for the commonly deleted regions of Prader-Willi, Angelman, Williams, Smith-Magenis, and DiGeorge/velocardiofacial syndromes in a single hybridization. The probes were differentially labeled, allowing multicolor detection, and 200 individual samples were screened in a blinded fashion. For all patients found by MultiFISH to have deletions, the deletions were originally identified and/or later confirmed by use of single-probe FISH analysis in our diagnostic cytogenetics laboratory. One patient, who was referred for developmental delay and was shown to have a normal G-banded karyotype, was identified by MultiFISH as having a micro-deletion at the DiGeorge/velocardiofacial commonly deleted region. Forty-six of the 200 total samples were tested for microdeletions by use of single FISH probes in the diagnostic laboratory. Ten of these cases were found to have deletions, and all deletions were subsequently detected by use of MultiFISH screen performed in a blinded fashion. Additionally, for all 200 patients tested by use of MultiFISH, no false-positive deletion results were observed. We demonstrate the ability of this technique to scan for and to identify microdeletions in a proportion of patients whose routine karyotype appears normal yet who are mentally retarded and/or developmentally delayed.

Child↗
PubMed2001

Thyroid-infiltrating B lymphocytes in Graves' disease are related to marginal zone and memory B cell compartments.

B lymphocytes that infiltrate the thyroid (Thy-B cells) in Graves' patients appear to be implicated in the pathophysiology of this disorder. The goal of the present study was to examine the nature of these Thy-B cells. To this end, Thy-B lymphocytes were isolated from surgical thyroidal samples, and their phenotype was determined by using mouse monoclonal antibodies (mAb) directed against a wide variety of surface markers, followed by flow cytometry multicolor analysis. The results show that most Thy-B cells (approximately 60%) exhibited IgM(+) IgD(low to -) surface immunoglobulin (Ig) profile, whereas the minor cell fraction (approximately 30%) consisted of switched IgG(+) memory B lymphocytes. Thy-B cells expressed low levels of CD5, CD23, and CD62L, which distinguished them from the resting B-cell pool, the major B-cell subset in the blood. In addition, they lacked CD38, CD10, and CD71, characteristic molecules for the germinal center B lymphocytes. In addition, Thy-B lymphocytes showed peculiar patterns both of adhesion molecules (CD62L(-), CD44(intermediate)), and of activation molecules (CD69(+), CD80(+), and, in part, CD95(+)). Taken together, these results suggest that the Thy-B lymphocyte subset consists of a combination of IgM(+) B cells resembling marginal zone B lymphocytes, and isotype-switched memory B cells.

Adolescent↗
PubMed2006

Long lasting control and lack of pathogenicity of the attenuated Rev-independent SIV in rhesus macaques.

A cohort of 22 rhesus macaques of Indian origin infected as neonates, juveniles, or adults by Rev-independent strains of SIV was monitored over several years. After the initial acute phase, virus replication was controlled and plasma virus loads were persistently below the threshold of the assay. The animals were monitored for up to 7.6 years after infection for viral loads, cellular and humoral immune responses, hematological changes, and overall health and no signs of immune dysfunction or AIDS were observed. This study represents several years of additional observation compared to the previously published results, and indicates that the Rev-independent SIV clones tested do not cause AIDS-like progressive disease within 7.6 years from infection. All the animals showed persistent humoral and cellular SIV-specific immune responses, consistent with chronic infection. Different Rev-independent SIV strains showed similar properties and lack of pathogenicity. Multicolor flow cytometric analysis demonstrated preservation of the Central Memory subset of T cells in the attenuated SIV-infected animals. This study demonstrates a potent, long-lasting control of the Rev-independent attenuated SIV in macaques independent of the age at virus exposure.

Animals↗