alpha- and beta-dystroglycan (DG) were first identified as members of an oligomeric, transmembrane complex expressed in muscle and linking laminin (LN) in the extracellular matrix (ECM) to dystrophin in the submembraneous cytoskeleton. This dystrophin-associated glycoprotein complex (DGC) has been proposed to perform a structural role in skeletal muscle, its loss leading to loss of membrane integrity, muscle fiber degeneration and muscular dystrophy. alpha- and beta-DG appear to form the core of the DGC since alpha-DG is a high affinity LN receptor while beta-DG is a transmembrane protein that anchors alpha-DG to the membrane and interacts with dystrophin intracellularly. In order to determine the involvement of DG in skeletal muscle homeostasis and in LN assembly, we generated mouse muscle cell lines deficient in DG expression. Extensive characterization of these cells revealed that DG is essential for LN assembly on the surface of mature myotubes but that it is not involved in the maintenance of membrane integrity in culture. However, DG-deficient cells show increased apoptotic cell death during and after the period of myoblast differentiation into myotubes, indicating that DG is important for muscle cell survival. / The ECM molecule agrin has been implicated in the induction of acetylcholine receptor (AChR) aggregation at the neuromuscular junction (NMJ). The C-terminus of agrin shares significant homology with the region of LN that interacts with alpha-DG; we therefore reasoned that alpha-DG could be an agrin receptor. Ligand overlay assays revealed that alpha-DG binds agrin with high affinity and antibody perturbation experiments indicated that alpha-DG is involved in agrin-induced aggregation of AChRs. The role of alpha-DG in AChR aggregation was further studied using the DG deficient muscle cell lines. We found that alpha-DG is involved in the later stages of agrin-induced AChR aggregation. / We further localized DG and two of its intracellular ligands, dystrophin and its autosomal homologue utrophin, to a synaptic layer in the retina suggesting a role for DG in central nervous system synapses. DG, utrophin and LN are also co-expressed around blood vessels indicating a possible function in blood-brain barrier homeostasis.

No description available.

Clouston hidrotic ectodermal dysplasia (BED) is an autosomal dominant skin disorder that is characterized by nail dystrophy, hair defects and palmoplantar hyperkeratosis. This condition has been described in families of various ethnic origins but is particularly common in the French Canadian population. Using linkage analysis in eight French Canadian families segregating HED, we mapped the HED gene to the pericentromeric region of chromosome 13q with a combined two-point lod score of 8.12 at zero recombination from the marker D13S175. Haplotype analysis allowed us to define D13S143 as the telomeric flanking marker for the HED candidate region. We tested five genes that map to this region, connexin 26, connexin 46, fibroblast growth factor 9, zinc-finger ZNF198 and alpha tubulin TUBA2, for involvement in HED by PCR-SSCP analysis. No mutation specific to HED was found in any of them suggesting that they most likely are not defective in this disease. / To facilitate the identification of the HED gene, we constructed a radiation hybrid (RH) map of 48 loci surrounding the HED locus on chromosome 13q. This map integrates 3 genes (TUBA2, GJbeta2 and FGF-9) and 18 ESTs with 27 markers including 19 polymorphic loci. A major inconsistency in order involving a reversed interval of six loci was found between our RH map and a YAC contig established in the region. We used Fiber-FISH and FISH on interphase nuclei to confirm our order. To refine the localization of the HED gene, we isolated eight new chromosome 13q polymorphic (CA)n markers and used seven of them along with three others in genetic analysis of a multiethnic group of 29 HED families. We demonstrated genetic homogeneity in HED in four families of French, Spanish, African and Malaysian origins and showed evidence for a strong founder effect in families of French Canadian origin. Recombination mapping placed the HED gene in a 2.4 cM region flanked by D13S1828 proximally and D13S1830 distally. Multipoint linkage and linkage disequilibrium analyses finely mapped the HED gene at 0--0.08 cM telomeric to D13S1835. These studies will greatly facilitate the physical mapping and positional cloning of the HED gene.

No description available.

In this study, RAPD (Randomly Amplified Polymorphic DNA) and SCAR (Sequence Amplified Characterized Region) markers found within 5 centiMorgans of known disease resistance loci in L. sativa were tested for their potential use in MAS. Out of thirty RAPD and SCAR markers evaluated, ten were found to be reliable predictors of disease resistance or susceptibility across a wide range of commercial and reference cultivars. Direct sequencing of seven selected markers did not reveal any significant similarity with known sequences. Three SNPs (Single Nucleotide Polymorphism) associated with two markers found in close proximity to corky root (cor) and Lettuce mosaic virus resistance (mo12) genes were identified. This information was used in the development of a non-electrophoresis PCR-based assay called FRET (Fluorescence Resonance Energy Transfer) hybridization probes assay.

The genetics and epigenetics of cortisone-induced cleft palate in the mouse have been examined. The SW/Fr strain, in which 6% of newborns have a cleft palate in the absence of treatment, has the greatest reactivity to cortisone of any strain tested so far and closes it palate comparatively late in development. After cortisone treatment, the mean of the distribution on palate closure stage is shifted towards later gestational ages without changing the variance. / The genetic basis for the DBA/2-C57BL/6 difference in susceptibility to cortisone-induced cleft palate is relatively simple. One dominant gene on chromosome 5 contributes predominantly to the strain difference in susceptibility, but the embryonic response appears also to be influenced by genes on the X chromosome. The H-2 haplotype does not affect the cortisone-induced cleft palate response in the two congenic strains C57BL/10 (B10) and B10.A by altering the stage of palate closure.

Little is known about the mechanism of virus disease resistance in plants. The aim of the work presented here was to answer whether disease resistance is offered within the cell or at the level of intercellular movement of the virus. The protoplast system was used for this purpose. Conditions were optimized to isolate viable protoplasts from the leaves of Lactuca sativa cultivars. Protoplasts and leaves from resistant and susceptible Lactuca sativa cultivars were inoculated separately with turnip mosaic virus (TuMV) and lettuce mosaic virus (LMV), Virus multiplication was examined over time using enzyme-linked immunosorbent assay. Resistant cv. Kordaat did not support TuMV multiplication in protoplasts as well as in leaves. The results indicated that resistance to TuMV is available within the cell. The results ruled out the possibility of involvement of cell to cell movement and resistance to TuMV seems to be constitutive. On the other hand, protoplasts and leaves from both resistant and susceptible lettuce cultivars supported LMV multiplication. This suggested that resistance to LMV may not be offered within the cell. The results also indicated that the resistance to LMV was partly due to a hypersensitive response though virus was still able to spread systemically. To contribute towards mapping of the Tu resistance gene, the genotype of F$ sb2$ individuals was determined by screening an F$ sb3$ population from 71 F$ sb2$ individuals of a cross between cv. Calmar and cv. Kordaat for TuMV-infection. These data were useful for the production of bulks around the Tu locus to facilitate the search for new molecular markers linked to the Tu gene.

No description available.

Bleomycin-induced pulmonary fibrosis (BIPF) is a disease caused by the chemotherapeutic bleomycin in which normal lung tissue is replaced with fibrous tissue that is unable to fulfill the normal functions of oxygen exchange in the lung. The development of this disease is dictated, in part, by a set of genes governing susceptibility. Knowledge of such genetic modifiers offers novel therapeutic targets and improved understanding of the pathways involved in the disease process. Our method integrates different data types to identify genes that have a single nucleotide polymorphism (SNP) disrupting a transcription factor binding site that modifies the outcome of BIPF. Our current approach examines over 7 million SNPs, phenotypes from 11 inbred mice strains, mRNA expression data, linkage data, and over 600 transcription factor binding sites from the TRANSFAC database. Each gene is scored with respect to each data type and then integrated using a weighted multiplicative model. Our integrative method produces a list of potential genetic modifiers that will be validated using allelic imbalance tests, existing knockout mice if available, siRNA or antibodies. By investigating these genes, we have identified several that are related to known genetic modifiers or others that make biological sense such as H2-Q2, an antigen presentation gene, and Runx1, a transcription factor known to interact with the known BIPF genetic modifiers Smad3 and Cdkn1a.

CDKN2A/p16 is a cell cycle inhibitor which blocks abnormal cell growth and proliferation. The CDKN2A gene is frequently mutated or deleted in a wide variety of tumour types. Germline mutations have also been identified in familial atypical multiple mole melanoma (FAMMM) pedigrees. However, the role of CDKN2A in hereditary cancer is uncertain. To explore the relationship between CDKN2A germline mutations and risk of cancer, 75 families with cancers at multiple sites were analysed for germline mutations in the CDKN2A gene. A Met53Ile mutation was found in a non-FAMMM kindred with multiple cancers, including one case of melanoma. The Met53Ile mutation has been previously reported in three Australian FAMMM kindreds. A known Ala148Thr polymorphism was also detected in 5 individuals. No other families were found to have CDKN2A alterations. There were no reported CDKN2A mutations in families without cases of melanoma. Analysis of microsatellite markers adjacent to CDKN2A on chromosome 9p21 revealed that this family shares a common haplotype with one other family with this mutation, suggesting that Met53Ile is a founder mutation. These results suggest that while CDKN2A mutations are not restricted to FAMMM pedigrees, they are very rare or absent in families with individuals without melanoma.