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PubMed2001

Parental mosaicism of JAG1 mutations in families with Alagille syndrome.

The Alagille syndrome (AGS), a congenital disorder affecting liver, heart, skeleton and eye in association with a typical face, is an autosomal dominant disease with nearly complete penetrance and variable expression. AGS is caused by mutations in the developmentally important JAG1 gene. In our mutation screening, where 61 mutations in JAG1 were detected, we identified five cases where mosaicism is present. Our results point to a significant frequency of mosaicism for JAG1 mutations in AGS of more than 8.2%. Because mosaicism may be associated with a very mild phenotype, the appropriate diagnosis of AGS and consequently the determination of the recurrence risk can be complicated.

Alagille Syndrome↗

PubMed2006

Postzygotic mutation and germline mosaicism in the otopalatodigital syndrome spectrum disorders.

The otopalatodigital syndrome (OPD) spectrum disorders are a heterogeneous group of skeletal dysplasias caused by mutations in the X-linked gene, FLNA. All OPD spectrum disorders (otopalatodigital syndromes types 1 and 2, frontometaphyseal dysplasia and Melnick-Needles syndrome) exhibit significant interfamilial variability in their expressivity, especially in female subjects. Factors contributing to this may include allelic heterogeneity, variation in the degree of skewing of X inactivation or, conceivably, mosaicism for the underlying causative mutation. We report here monozygotic twin sisters who are discordant for the severe phenotype, Melnick-Needles syndrome, associated with the heterozygous mutation, 3596C>T. We also describe two brothers with otopalatodigital syndrome type 1 due to the FLNA mutation 620G>A. The mutation is not detectable in the blood leucocytes of their clinically unaffected mother, indicating that she is a germline mosaic for the condition. The description of somatic mutations and germline mosaicism in FLNA has implications for clinical and molecular diagnosis, phenotypic expression and genetic counseling of families with these disorders.

Adolescent↗

PubMed2004

Analysis of cell proliferation in Drosophila wing imaginal discs using mosaic clones.

Experimental data on spatial and temporal distributions of mosaic clones in Drosophila wing imaginal disc were analyzed. Long-lived proliferation centers (PR1, PR2, and PR3) and areas with decreased proliferation activity were found in the notum region of the disc. Simulation of the growth kinetics of mosaic patches demonstrated that the cell cycle in proliferation centers PR2 and PR3 was shorter than the average cycle in the disc and in the center PR1. A nonrandom clustering of rapidly dividing cells was observed in the PR2, but not in the other cases. The reason why the cell-cycle duration and the clustering of dividing cells may not coincide is discussed in terms of the recruitment of nondividing cells into the cell cycle. The simulation of the time course of the first and second moments of the size distribution of mosaic clones allowed the variance of cell-cycle progression rates to be determined and demonstrated that a model with a continuous cell-cycle rates gave a better fit to the data than the transition probability model of Smith and Martin.

Animals↗

PubMed2003

Exclusion of mosaicism in Spanish haemophilia A families with inversion of intron 22.

Inversion of intron 22, the most frequent mutation event in haemophilia A (HA), was tested in our HA families to diagnose the females at risk of being carriers, to trace the origin of the mutation and to investigate the presence of germinal or somatic mosaicism. A total of 166 females belonging to 54 families with inversion, were analysed. All but one of the mothers tested were carriers and the inversion originated almost exclusively in male germ cells. Somatic or germline mosaicisms were excluded in 53 of these women and in 20 grandfathers, suggesting that such mosaicisms may be a rare event in families with inversion of intron 22.

Chromosome Inversion↗

PubMedDate not supplied

Genomic analysis of ABO chimeras and mosaics using hematopoietic colony-derived DNA.

BACKGROUND: While there are many case reports dealing with ABO mosaicism and chimerism, there have been few attempts to determine the patient's genotype. STUDY DESIGN AND METHODS: Peripheral blood and buccal mucosa were obtained from three persons with ABO mosaicism or chimerism. DNA extracted from hematopoietic progenitor cell-derived colonies and from peripheral blood and buccal mucosa were analyzed by polymerase chain reaction-restriction fragment length polymorphism methods. In addition, analyses of short tandem repeat markers were carried out. RESULTS: Hematopoietic progenitor cell-derived DNA analysis revealed that, in two of the three persons there were 2 apparently distinct progenitor cell lineages whose percentages were close to those in the peripheral blood of the patients, as analyzed by flow cytometry; the exception was Subject 3, who had myelodysplastic syndrome (MDS). Short tandem repeat analysis showed that the former two subjects had two pairs of ABO alleles and the latter subject, with MDS, had loss of heterozygosity in some colony-derived DNA as well as blood DNA. CONCLUSION: The subjects without MDS had two distinct hematopoietic cell lineages that led to their ABO chimeric status. The subject with MDS was assumed to have an ABO mosaicism caused by the somatic deletion of the ABO gene in the hematopoietic progenitor cells.

ABO Blood-Group System↗

PubMed1989

[Fertility and Turner mosaicism syndrome].

Six patients with a Turner mosaicism are reported. All six women were investigated for sterility or infertility. Four of six patients had a total of nine pregnancies: six abortions, one stillbirth, two normal children. The literature contains reports of 17 pregnancies in 10 women with 45.X karyotype and 106 pregnancies in 48 women with mosaicism. Miscarriages, stillbirths and malformations were common. These women need special counselling and in case of a pregnancy amniocentesis is indicated. We discuss the pathogenesis of reduced fertility with Turner patients and explain the problems related to the cystogenetic diagnosis of the Turner-Mosaic Syndrome.

Abortion, Spontaneous↗

PubMed1997

A case of mosaic tetrasomy 12p (Pallister-Killian Syndrome) diagnosed prenatally: comparison of chromosome analyses of various cells obtained from the patient.

A pregnant woman was referred to our hospital at the 29th week of gestation with the symptom of polyhydramnios; diaphragmatic herniation of the fetus was suspected. Fetal chromosome anlaysis was performed using fibroblasts obtained by aminocentesis, and mosaicism of 46,XX and isochromosome of 12p were diagnosed. Out of 50 karyotyped cells, 19 (38.0%) showed the tetrasomy of the isochromosome of 12p. The mother vaginally delivered a baby girl who died just after delivery. The analysis of cord blood lymphocytes revealed only 0.5% incidence of tetrasomy of 12p. The incidence of tetrasomy was 8.0% for the placental chorionic villi, 48.0% for the fibroblasts obtained from the umbilical cord, and 70.0% for the skin fibroblasts. Thus, the diagnosis of Pallister-Killian Syndrome (PKS) is confirmed by mosaicism of i(12p), that is, the affected patients exhibit tissue-specific mosaicism, with the abnormal karyotype expression in limited lymphocytes, but marked in fibroblasts.

Adult↗

PubMed2000

Genetic mosaic analysis based on Cre recombinase and navigated laser capture microdissection.

Defining molecular interactions that occur at the interface between "normal" and "abnormal" cell populations represents an important but often underexplored aspect of the pathogenesis of diseases with focal origins. Here, we illustrate an approach for conducting such analyses based on mosaic patterns of Cre recombinase expression in the adult mouse intestinal epithelium. Transgenic mice were generated that express Cre in the stem cell niche of crypts located in specified regions of their intestine. Some of these mice were engineered to allow for doxycycline-inducible Cre expression. Recombination in all pedigrees was mosaic: Cre-expressing crypts that supported recombination in all of their active multipotent stem cells were located adjacent to "control" crypts that did not express Cre at detectable levels. Cre-mediated recombination of a floxed LacZ reporter provided direct evidence that adult small-intestinal crypts contain more than one active multipotent stem cell, and that these cells can be retained in both small-intestinal and colonic crypts for at least 80 d. A method was developed to recover epithelial cells from crypts with or without recombination for subsequent gene expression profiling. Stained sections of intestine were used to create electronic image templates to guide laser capture microdissection (LCM) of adjacent frozen sections. This navigated form of LCM overcomes problems with mRNA degradation encountered when cells are marked directly by immunohistochemical methods. Combining Cre-engineered genetic mosaic mice with navigated-LCM will allow biology and pathobiology to be explored at the junction between normal and perturbed cellular cohorts.

Animals↗

PubMed1972

Autonomy or nonautonomy of gene effects in mosaics.

The dominant autosomal gene Msc (Multiple sex combs) of Drosophila causes the appearance of sex combs on the second and third legs and a reduction of size of sex combs on first legs. The effect of Msc was studied in mosaic flies in which non-Msc spots were present on a Msc background. Mosaics were due to somatic crossing-over induced by x-rays. Analysis of mosaics suggested autonomy of the action of Msc, provided that the somatic crossing-over occurs less frequently proximally to the Msc locus than distally. This unusual ratio of somatic crossing-over was confirmed by a separate experiment with the gene Kinked, whose locus is very close to Msc.

Animals↗

PubMed1972

Assembly of tobacco mosaic virus in vitro: effect of state of polymerization of the protein component.

The in vitro assembly of tobacco mosaic virus from its constituent RNA and protein was followed by methods of electron microscopy. The effect of the state of polymerization of the protein upon the initiation of assembly of tobacco mosaic virus rods, and the subsequent rod elongation, was investigated. Protein in two identifiable states of polymerization was used: the 20S "disc", consisting of 34 monomers arrayed as a two-ring structure, and the 4S "A-protein", consisting of polymers in the trimer range of size. It is concluded, in confirmation of results of others, that rod assembly is initiated by the attachment of one end of the RNA chain of tobacco mosaic virus to one (or possibly a few) disc structure. Rod elongation, on the other hand, is found to take place by the sequential addition of structures of the size of A-protein, or smaller, to the previously initiated rods.

Chemical Phenomena↗

PubMed1975

Sequence of 71 nucleotides at the 3'-end of tobacco mosaic virus RNA.

The sequence of the first 71 nucleotides from the 3'-OH end of tobacco mosaic virus RNA has been determined. After total T1 ribonuclease digestion of the viral RNA, the oligonucleotide C-C-C-A-OH, which originates from the 3'-OH terminus of the RNA, may be readily detected by electrophoresis at pH 2.5 or pH 3.0; it is the only oligonucleotide that migrates toward the cathode at these pHs. This property has been used to screen the purified products of partial T1 ribonuclease digestion of tobacco mosaic virus RNA for the fragment originating from the 3'-end of the native molecule. The sequence of nucleotides in the 3'-terminal fragment, identified in this manner, was determined by radiochemical methods. The fragment contained 71 nucleotides; no abnormal bases could be detected. Although it has been reported that the 3'-end of tobacco mosaic virus RNA is a substrate for aminoacylation by the histidyl-tRNA synthetase of yeast or Escherichia coli, we were unable to fold the sequence into the cloverleaf structure characteristic of tRNAs.

Base Sequence↗

PubMed1976

Translation of turnip yellow mosaic virus RNA in vitro: a closed and an open coat protein cistron.

Sucrose gradient centrifugation of heat-denatured RNA of turnip yellow mosaic virus permitted the isolation of five RNA classes with molecular weights ranging from 2.0 to 0.25 X 10(6). The infectivity was shown to be confined to an RNA molecule of molecular weight 2.0 X 10(6). No significant increase in infectivity was obtained by combination of the latter RNA with the RNA classes of smaller size. Translation in vitro of the RNAs of different size classes in a wheat germ cell-free system revealed that the infectious RNA (molecular weight 2.0 X 10(6) does not promote the synthesis of the coat protein of turnip yellow mosaic virus. Efficient production of this coat protein was found exclusively when the smallest RNA class (molecular weight 250,000) was used as a messenger. It is concluded that RNA molecules of turnip yellow mosaic virus of molecular weight 2.0 X 10(6) contain a closed coat protein cistron and that RNA molecules of molecular weight about 2 to 3 X 10(5) with an open coat protein cistron can be isolated from the virions.

Cell-Free System↗

PubMed1987

Coat protein gene sequence of tobacco mosaic virus encodes a host response determinant.

The common strain and tomato strain of tobacco mosaic virus (TMV) are known to be closely related to each other. However, plants with the N' gene, such as Nicotiana sylvestris and Nicotiana tabacum L. cv. Bright Yellow, respond differently to infections by these viruses. In the N' plants, TMV-OM (common strain) spreads systemically with mosaic symptoms, whereas TMV-L (tomato strain) induces the necrotic response of plants, causing local lesions. To reveal the viral factor of TMV-L inducing the necrotic response, we have constructed several recombinant viruses between the two strains, in which TMV-L RNA was partly replaced by TMV-OM RNA. The recombinant viruses having the coat protein gene sequence of TMV-OM in place of TMV-L produced no necrotic local lesions but spread systemically with mosaic symptoms in the N' plants. On the other hand, the recombinant viruses having TMV-OM-derived sequences other than the coat protein gene sequence, and in which the coat protein gene sequence of TMV-L still remained, produced necrotic local lesions. These observations indicate that the viral factor of TMV-L responsible for the necrotic response of the N' plants is coded in the coat protein gene sequence.

Base Sequence↗

PubMed1990

Molecular characterization and biological function of the movement protein of tobacco mosaic virus in transgenic plants.

We previously demonstrated, in transgenic tobacco plants, that the role of the movement protein (MP) of tobacco mosaic virus is to facilitate the cell-to-cell spread of viral progeny during infection. An analysis of different tissues of these transgenic plants indicated that the MP accumulated in leaf, stem, and root tissue. The highest levels were detected in older leaves. The relative levels of MP in leaf tissue from transgenic plants were equivalent to, or higher than, the levels of MP in tobacco mosaic virus-infected leaf tissue. Results of subcellular fractionation of homogenates of transgenic leaf tissue showed that the MP was most abundant in the cell wall fraction of older leaves and that the protein remained at high levels in the cell wall fraction as the leaves continued to age. Significant levels of the MP were detected in a crude membrane/organelle fraction and a soluble fraction in younger leaves but decreased to low levels in older leaves. These results suggest that the MP accumulates and is stable in cell walls. We have previously shown that the MP modifies the molecular exclusion limit of plasmodesmata, which is consistent with the hypothesis that plant viruses move from cell to cell through altered plasmodesmata. We show here that the ability of the tobacco mosaic virus MP to modify the molecular exclusion limit of plasmodesmata in tobacco depends on the developmental stage of the leaf. The implications of these findings on understanding virus movement and how plasmodesmata function are discussed.

Capsid Proteins↗

PubMed1995

High-affinity RNA-binding domains of alfalfa mosaic virus coat protein are not required for coat protein-mediated resistance.

A virus-based vector was used for the transient expression of the alfalfa mosaic virus coat protein (CP) gene in protoplasts and plants. The accumulation of wild-type CP conferred strong protection against subsequent alfalfa mosaic virus infection, enabling the efficacy of CP mutants to be determined without developing transgenic plants. Expression of the CP mRNA alone without CP accumulation conferred weaker protection against infection. The activity of the N-terminal mutant CPs in protection did not correlate with their activities in genome activation. The activity of a C-terminal mutant suggested that encapsidation did not have a role in protection. Our results indicate that interaction of the CP with alfalfa mosaic virus RNA is not important in protection, thereby leaving open the possibility that interactions with host factors lead to protection.

Alfalfa mosaic virus↗

PubMed1996

The N gene of tobacco confers resistance to tobacco mosaic virus in transgenic tomato.

It has been proposed that cloned plant disease resistance genes could be transferred from resistant to susceptible plant species to control important crop plant diseases. The recently cloned N gene of tobacco confers resistance to the viral pathogen, tobacco mosaic virus. We generated transgenic tomato plants bearing the N gene and demonstrate that N confers a hypersensitive response and effectively localizes tobacco mosaic virus to sites of inoculation in transgenic tomato, as it does in tobacco. The ability to reconstruct the N-mediated resistance response to tobacco mosaic virus in tomato demonstrates the utility of using isolated resistance genes to protect crop plants from diseases, and it demonstrates that all the components necessary for N-mediated resistance are conserved in tomato.

Base Sequence↗

PubMed1998

Ophthalmic manifestations of trisomy 8 mosaic syndrome.

Trisomy 8 mosaicism can present with a varied clinical picture. A significant number of cases have ocular manifestations. The most commonly reported in the literature have been corneal abnormalities and strabismus. We present a case of trisomy 8 mosaic syndrome with very different ophthalmic manifestations, some of which are previously unreported in the literature. The patient who was known to have trisomy 8 mosaic syndrome was referred with concerns about his visual abilities. He had a characteristic facial dysmorphism and other systemic features associated with this condition. Ophthalmic features included bilateral Duane's syndrome, bilateral myopic astigmatism, congenital pendular nystagmus, and macula hypoplasia. Electrodiagnostic tests confirmed extensive abnormality of cone function in both eyes. This case is discussed in relation to a review of the literature.

Astigmatism↗

PubMed2004

Ocular manifestations of mosaic trisomy 22: a case report and review of the literature.

Mosaic trisomy 22 is rare, but can be compatible with prolonged life. Patients with mosaic trisomy 22 usually present with intrauterine growth retardation, mental retardation, failure to thrive, and craniofacial asymmetry. We report the case of a five-year-old boy who had a birth weight of 3.8 kg and normal developmental milestones. He presented with unilateral ocular manifestations of ptosis, double elevator palsy, high myopia, and choroidal coloboma involving the macula. Cytogenetic evaluation showed a low level of trisomy 22 in peripheral blood lymphocytes (1 in 100) and in cultured fibroblasts from a conjunctival biopsy of the affected eye (1 in 60). Our case demonstrates the value of chromosomal analysis of the tissues involved rather than just karyotyping of the blood lymphocytes to detect mosaicism in patients with localised and unilateral congenital malformations.

Abnormalities, Multiple↗