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At least 829 records · Page 46Linked to original sources
PubMed1981

An ultrastructural study of the maternal-effect embryos of the ac/ac mutant of Pleurodeles waltl showing a gastrulation defect.

Embryos of the ac/ac maternal-effect mutant in Pleurodeles waltl show disturbed epibolic movement during gastrulation. At the early gastrula stage, ectoderm cells begin to sink in at random sites in the animal half of the embryo. At the advanced gastrula stage the ectodermal pits develop into grooves. Electron microscopical analysis shows that many cells in the bottom of the pits and grooves have narrowed apices and bear many microvilli, while the cortical cytoplasm is dense, filamentous and underlain by a stratum of vesicles. These findings are interpreted as indicating that ectoderm cells contract rather than expand leading to disturbed epibolic movement.

Animals↗
PubMed1981

Association of Vibrio cholerae mutants with the intestinal mucosa of infant mice.

Scanning electron microscopy (SEM) was used to observe the nature of association of mutant strains of Vibrio cholerae to infant mouse intestinal segments. Parental strain Inaba CA 401 was compared to the following mutant phenotypes: nonchemotactic, nonchemotactic reduced motility, flagellated nonmotile, nonflagellated nonmotile, and mucin nonutilizing. The virulence of the different strains was determined by oral-intra-gastric inoculation of seven-day-old mice. Localization of the parental strain during the course of infection in the patent gut of infant mice was followed by the fluorescent antibody (FA) technique. The highly virulent parental strain rapidly penetrated intervillus spaces in the upper and lower regions of the small intestine. By SEM the organism also associated markedly with the mucosal surface of intestinal segments. However, the vibrios were associated predominately with the intestinal mucin rather than the epithelial cell surfaces of villi. Nonchemotactic vibrios retained full virulence and ability to associate with the mucosa. The nonchemotactic strain with a reduced rate of motility was partially deficient in these properties. Nonmotile vibrios of either type were markedly reduced in both properties. The mucin nonutilizing strain associated normally but was weakly virulent. Low virulence of this strain may be due to a reduced ability of the organisms to multiply in the mucin.

Animals↗
PubMed1978

Regional differences in the morphology and motility of mesodermal cells from the early wing-bud of normal and talpid3 mutant chick embryos.

A method of culturing has been employed to compare the properties of cells migrating from small mesodermal explants taken from different regions of normal and mutant limb-buds at different stages of development. An analysis by time-lapse cinematography of the morphology and mobility of cells migrating from explants defines a distal region within the limb-bud where these properties are distinct from those of cells from more proximal regions. In the normal wing-bud distal cells subjacent to the apical ectodermal ridge possess a characteristic multipolar morphology and translocate slowly in vitro. Cells from more proximal regions tend to be bipolar and translocate more rapidly. Distal and proximal cells also probably differ in their adhesive strengths. In the mutant, talpid3, distal and proximal cells do not differ in the above properties and cells from all regions of the limb-bud are multipolar, translocate slowly and are more adhesive than normal cells. A study of light micrographs and scanning electron micrographs suggests that these regional differences are found in the limb-bud in vivo and are not merely an effect produced by the in vitro culturing system.

Animals↗
PubMed1994

Morphological and colour mutants of Aspergillus fumigatus.

By using the scanning electron microscope the morphological deviations of 17 colour mutants of Aspergillus fumigatus were characterized. These mutants originated by genetic blocks in various stages of conidiophores and conidia differentiation. The complementation test was carried out with the light-pigmented mutants. The group of allelic strains was found and 4 diploid strains were isolated.

Aspergillus fumigatus↗
PubMed1995

Thymic nurse cell rescue of early CD4+CD8+ thymocytes from apoptosis.

We have now developed temperature sensitive lines of thymic nurse cells (TNCs), using the SV40 viral mutant tsA58, that maintain the ability to selectively internalize a subpopulation of alpha beta TCR+CD4+CD8+ thymocytes in vitro. One line, tsTNC-1, was shown to be able to rescue a subset of CD4+CD8+ thymocytes from programmed cell death at 32 degrees C, the temperature at which binding and internalization were detected. Rescue was significantly diminished at 38 degrees C, the temperature at which thymocyte binding was not observed. The rescued population of thymocytes showed a reduced level of apoptosis as measured by the DNA fragmentation assay. TNC rescue resulted in a shift of CD4+CD8+ thymocytes from immature TCRlow PNArhigh cells to the more mature TCRint PNArlow phenotype but no changes in cell surface levels of HSA nor CD69 were detected. The rescue activity of tsTNC-1 cells at 32 degrees C was significantly reduced with the addition of antibodies to either class I or class II MHC antigens. These results suggest that we have established TNC lines, using the SV40 viral mutant tsA58, that have the ability to rescue a subset of the TNC interactive thymocyte population from programmed cell death. The thymocyte population rescued by TNCs matures to a phenotype within the double positive stage of development that is indicative of positive selection.

Animals↗
PubMed1996

A scanning electron microscopic investigation of genetic emphysema in tight-skin, pallid, and beige mice, three different C57 BL/6J mutants.

Three mutants of the C57 BL/6J strain, i.e., the tight-skin (Tsk), pallid (pa), and beige (bg) mice have been reported to develop spontaneous emphysema. However, the pathogenic mechanisms of this lesion may be different in the three mutants. Differences and similarities of these models were investigated by means of scanning electron microscopy. A light microscopic investigation provided the background for the SEM study. C57 BL/6J (control), pa, Tsk, and bg mice were killed when they were 1, 12, and 24 months old. At light microscopic investigation the lungs of the controls appeared normal at all ages. Those of the pa mice had normal appearance at 1 month, showed a few areas of air space enlargement with destruction of alveolar septa at 12 months, and had a generalized enlargement of the air spaces associated with distortion of alveolar septa at 24 months. The Tsk mice had a generalized panlobular emphysema at all ages. The lungs of the bg mice showed at all ages a generalized enlargement of the air spaces not accompanied by changes of the alveolar septa. At scanning electron microscopy the lung parenchyma of control mice was essentially normal at all ages. Both alveolar ducts and alveoli increased in size (the latter also in depth) with age. The number of interalveolar pores (Np) increased by 54% between 1 and 12 months of age and by 49% between 12 and 24 months. The parenchyma of pa mice did not differ significantly from that of the controls at 1 month. At 12 months the alveoli appeared to be larger. At 24 months in some fields alveolar ducts were enlarged, the alveoli were also enlarged and very shallow. Np was not different from controls at 1 month but greater at 12 (+ 49%) and 24 (+ 26%) months. The parenchyma of Tsk mice of all ages appeared distorted with enlargement of alveolar ducts and sacs and with alveoli with a large number of pores. These changes increased with age. Np was larger than the controls at all ages (+ 59% at 1 month, + 119% at 12 months, and + 80% at 24 months). The parenchyma of the bg mice of all ages appeared disorganized with large alveoli of different shapes. There was a deterioration with age. No difference in Np was seen at any age between bg and control mice. Parenchymal changes characterized by distortion and enlargement of alveolar ducts and sacs were observed, even if with different onset and extent, in all mutants. However, an increase in Np, which is considered to represent the early development of emphysema, was found only in Tsk and pa mice. In Tsk mice, high Np values were observed at all ages, whereas in pa mice Np was increased only late in life when the pulmonary lesion develops. These differences indicate different pathogenetic mechanisms for these three mutants.

Aging↗
PubMedDate not supplied

[The development of a Proteus mirabilis macrocolony on a solid nutrient medium].

As revealed in this study, the macrocolony of Proteus mirabilis, formed on solid culture medium, may consist both of the main part and of sporadically appearing dissociating subcolonies, considerably differing one from another. The outer edge of the main part of the macrocolony of swarming cells is represented by bacteria located in three perpendicular directions. The next intermediate area consisting of two layers is represented by bacteria oriented, as a rule, in one direction. The center of the colony is made up of short microbial cells. Between the upper layer and the surface of agar an original subpopulation of microbial cells, forming a separate layer, has been detected; together they determine the planar sandwich-like architectonics of the macrocolony.

Culture Media↗
PubMed1998

Ultrastructural analyses of the Caenorhabditis elegans rol-6 (su1006) mutant, which produces abnormal cuticle collagen.

Roller mutants of Caenorhabditis elegans rotate around their long axis and move in circular paths. Isolation and sequence of the rol-6 gene of C. elegans have shown that it encodes a cuticle collagen. In this paper, we describe the morphological alterations seen in the cuticle of the right roller mutant rol-6 (su1006) at the ultrastructural level. Deep-etched replica analyses showed that the honeycomb elements, fibers organized in a pentagonal fashion above the fishbone fibrous layer, completely fill the intermediate layer, which is observed to be largely empty spaces in the wild-type strain. The honeycomb fibers appear to connect the cortical and basal regions of the mutant cuticle. These fibers are likely to be involved in generating the helical twist of the mutant animals. Deep-etched replicas also revealed a delicate network of filaments on the nematode surface.

Animals↗
PubMed2006

[Molecular diagnosis of retinoblastoma: molecular epidemiology and genetic counseling].

BACKGROUND AND OBJECTIVE: Retinoblastoma, a prototype of hereditary cancer, is the most common intraocular tumor in children and a potential cause of blindness from therapeutic eye ablation, second tumors in germ line mutation carriers, and even death when untreated. The molecular scanning of RB1 in search of germ line mutations in 213 retinoblastoma patients from Spain, Cuba, Colombia and Serbia, has led to the detection of 106 mutations whose knowledge is important for genetic counselling and characterization of phenotypic-genotypic relations. PATIENTS AND METHOD: Mutational study (PCR-sequentiation and microsatellites analysis) in patients with retinoblastoma, from Spain, Cuba, Colombia and Serbia. RESULTS: 45% of mutations, including most of the frame shift (FS), missense (MS) and splicing (SP), were new, while all nonsense mutations (NS) corresponded to hypermutable sites in RB1. Germ line mutations were found in 22% of unilateral sporadic patients. The incidence of SP plus MS mutations in this group of patients was greater (p = 0.018) than in bilateral patients. The frequency of SP mutations was higher (p = 0.0003) in Spain and France than in Germany and United Kingdom, while the incidence of NS mutations was lower (p = 0.0006). SP mutations were associated with the low penetrance phenotype and were also overrepresented (p = 0.018) in patients with delayed retinoblastoma onset. CONCLUSIONS: Mutational scanning of unilateral patients is important for genetic counselling and may help decipher the molecular mechanisms leading to low penetrance or expressivity. The functional characterization of mutations associated with low-penetrance or expressivity phenotypes and the molecular classification of tumors using multiple expression profiling is important for a better understanding of the retinoblastoma pathogenesis.

Child↗
PubMed2006

Novel mutations of dystrophin gene in DMD patients detected by rapid scanning in biplex exons DHPLC analysis.

Mutations in the dystrophin gene result in both Duchenne and Becher muscular dystrophies (DMD and BMD). Approximately 65% of all mutations causing DMD are deletions (60%) or duplications (5%) of large segments of this gene, spanning one exon or more. Due to the large size of the dystrophin gene (79 exons), finding point mutations has been prohibitively expensive and laborious. Recent studies confirm the utility of pre-screening methods, as denaturing high-performance liquid chromatography (DHPLC) analysis in the identification of point mutations in the dystrophin gene, with an increment of mutation detection rate from 65% to more than 92%. Here we suggest an alternative and convenient method of DHPLC analysis in order to find mutations in a more rapid and less expensive way by introducing the analysis of 16 couples of dystrophin amplicons, in biplex exons DHPLC runs. Using this new protocol of biplex exons DHPLC screening, new mutations were identified in four male patients affected by DMD who had tested negative for large DNA rearrangements.

Adult↗
PubMed2003

Mapping dominant-negative mutations of anthrax protective antigen by scanning mutagenesis.

The protective antigen (PA) moiety of anthrax toxin transports edema factor and lethal factor to the cytosol of mammalian cells by a mechanism that depends on its ability to oligomerize and form pores in the endosomal membrane. Previously, some mutated forms of PA, designated dominant negative (DN), were found to coassemble with wild-type PA and generate defective heptameric pore-precursors (prepores). Prepores containing DN-PA are impaired in pore formation and in translocating edema factor and lethal factor across the endosomal membrane. To create a more comprehensive map of sites within PA where a single amino acid replacement can give a DN phenotype, we used automated systems to generate a Cys-replacement mutation for each of the 568 residues of PA63, the active 63-kDa proteolytic fragment of PA. Thirty-three mutations that reduced PA's ability to mediate toxicity at least 100-fold were identified in all four domains of PA63. A majority (22) were in domain 2, the pore-forming domain. Seven of the domain-2 mutations, located in or adjacent to the 2beta6 strand, the 2beta7 strand, and the 2beta10-2beta11 loop, gave the DN phenotype. This study demonstrates the feasibility of high-throughput scanning mutagenesis of a moderate sized protein. The results show that DN mutations cluster in a single domain and implicate 2beta6 and 2beta7 strands and the 2beta10-2beta11 loop in the conformational rearrangement of the prepore to the pore. They also add to the repertoire of mutations available for structure-function studies and for designing new antitoxic agents for treatment of anthrax.

Animals↗
PubMed2001

Spontaneous in vivo reversion of an inherited mutation in the Wiskott-Aldrich syndrome.

The Wiskott-Aldrich syndrome (WAS) is an X-linked primary immunodeficiency disease, arising from mutations of the WAS-protein (WASP) gene. Previously, we have reported that mononuclear cells from WAS patients showed lack/reduced of the intracellular WASP (WASP(dim)) by flow cytometric analysis, and analysis of WASP by flow cytometry (FCM-WASP) was useful for WAS diagnosis. In this study, we report a WAS patient who showed the unique pattern of FCM-WASP. The patient had the small population of normal expression of WASP (WASP(bright)) mononuclear cells together with the major WASP(dim) population. The WASP(bright) cells were detected in T cells, not in B cells or in monocytes. Surprisingly, the molecular studies of the WASP(bright) cells revealed that the inherited mutation of WASP gene was reversed to normal. His mother was proved as a WAS carrier, and HLA studies and microsatellite polymorphic studies proved that the WASP(bright) cells were derived from the patient himself. Therefore, we concluded that the WASP(bright) cells were resulted from spontaneous in vivo reversion of the inherited mutation. Furthermore, the scanning electron microscopic studies indicated that WASP-positive cells from the patient restored the dense microvillus surface projections that were hardly observed in the WASP(dim) cells. This case might have significant implications regarding the prospects of the future gene therapy for WAS patients.

Adult↗
PubMed2003

Haemophilia B: from molecular diagnosis to gene therapy.

Thanks to its typical expression, haemophilia can be identified in writings from the second century AD. Haemophilia B, an X-linked recessive bleeding disorder due to factor IX (FIX) deficiency, has an incidence of about 1:30,000 live male births. The factor 9 (F9) gene was mapped in 1984 on Xq27.1. Haemophilia is diagnosed from prothrombin time, activated partial thromboplastin time, and FIX levels. Carrier females are usually asymptomatic and must be identified only with molecular analysis. Linkage analysis of F9 polymorphisms is rapid and inexpensive but limited by non-informative families, recombinant events, and the high incidence of germline mutations; thus, various procedures have been used for the direct scan of F9 mutations. We set up a novel denaturing high performance liquid chromatographic procedure to scan the F9 gene. This rapid, reproducible procedure detected F9 mutations in 100% of a preliminary cohort of 18 haemophilia B patients. Parallel to the development of more efficient diagnostic tools, the life expectancy and reproductive fitness of haemophilic patients have greatly improved and will continue to improve thanks to the use of less immunogenic recombinant FIX. Hopefully, new approaches based on gene therapy now being evaluated in clinical trials will revolutionise haemophilia B treatment.

Factor IX↗