The mdx mouse is an X-linked myopathic mutant, an animal model for human Duchenne muscular dystrophy. In both mouse and man the mutations lie within the dystrophin gene, but the phenotypic differences of the disease in the two species confer much interest on the molecular basis of the mdx mutation. The complementary DNA for mouse dystrophin has been cloned, and the sequence has been used in the polymerase chain reaction to amplify normal and mdx dystrophin transcripts in the area of the mdx mutation. Sequence analysis of the amplification products showed that the mdx mouse has a single base substitution within an exon, which causes premature termination of the polypeptide chain.

Recent advances in avian transgenesis have led to the possibility of utilizing the laying hen as a production platform for the large-scale synthesis of pharmaceutical proteins. Ovalbumin constitutes more than half of the protein in the white of a laid egg, and expression of the ovalbumin gene is restricted to the tubular gland cells of the oviduct. Here we describe the use of lentiviral vectors to deliver transgene constructs comprising regulatory sequences from the ovalbumin gene designed to direct synthesis of associated therapeutic proteins to the oviduct. We report the generation of transgenic hens that synthesize functional recombinant pharmaceutical protein in a tightly regulated tissue-specific manner, without any evidence of transgene silencing after germ-line transmission.chicken ͉ genetic modification ͉ lentivirus ͉ pharmaceutical

Cognitive impairment occurs in one-third of patients with Duchenne muscular dystrophy, a lethal X-linked, recessive disease caused by mutations in the dystrophin gene which is expressed in both brain and muscle, the two transcripts having alternative first exons. Previous reports have indicated that the 'brain-type' dystrophin transcript predominates in brain. Using in situ hybridisation with antisense oligonucleotides, expression of four distinct mRNAs in specific brain areas is demonstrated here; the 14 kb muscle-type and brain-type transcripts were found to coexist in cortical and hippocampal neurons and two new transcripts have been identified in dentate gyrus and cerebellar Purkinje neurons, respectively. The latter has a novel first exon which was isolated and sequenced from mouse and human, and which would encode a protein with a different amino-terminus from the known muscle- and brain-type isoforms. Mapping in human located this exon in a large intron between the muscle-type promoter and second exon of the dystrophin gene. This finding of four alternative transcripts regulated by different promoters in brain reveals a new complexity to dystrophin expression that may have important insights for mental retardation mechanisms.

The apolipoprotein E (APOE) ε4 allele is the major genetic risk factor for Alzheimer's disease (AD). Multiple regulatory elements, spanning the extended TOMM40-APOE-APOC2 region, regulate gene expression at this locus. Regulatory element DNA methylation changes occur under different environmental conditions, such as disease. Our group and others have described an APOE CpG island as hypomethylated in AD, compared to cognitively normal controls. However, little is known about methylation of the larger TOMM40-APOE-APOC2 region. The hypothesis of this investigation was that regulatory element methylation levels of the larger TOMM40-APOE-APOC2 region are associated with AD. The aim was to determine whether DNA methylation of the TOMM40-APOE-APOC2 region differs in AD compared to cognitively normal controls in post-mortem brain and peripheral blood. DNA was extracted from human brain (n = 12) and peripheral blood (n = 67). A methylation array was used for this analysis. Percent methylation within the TOMM40-APOE-APOC2 region was evaluated for differences according to tissue type, disease state, AD-related biomarkers, and gene expression. Results from this exploratory analysis suggest that regulatory element methylation levels within the larger TOMM40-APOE-APOC2 gene region correlate with AD-related biomarkers and TOMM40 or APOE gene expression in AD.

We have mapped human and mouse X chromosome‐specific genomic and cDNA probes through an interspecies Mus musculus/spretus pedigree which contains the mdx mutation. The positions of these markers relative to one another and to the mdx mutation were delineated. Using probes corresponding to segments of the human Duchenne muscular dystrophy (DMD) gene transcript, the position of a cross‐hybridizing mouse equivalent gene (mDMD) was located. In more than 200 animals mapped, three were identified which show recombination within this mDMD gene. Analysis of these three animals shows that the mDMD gene is oriented with its 5′ end centromeric and its 3′ end telomeric on the mouse X chromosome. Furthermore, their recombinational breakpoints are on either side of the mdx mutation, thus providing the first unequivocal demonstration that the mdx mutation is located within the mDMD gene and defining limits within that gene between which the mutation must lie. Within that segment the evidence indicates that there is no major deletion of an exon as detectable by Southern blot analysis in mdx animals. The mdx mouse becomes important as an animal model for the study of the expression of the DMD gene and its developmental consequences, for transgenic and other corrective manipulations.