Efficient methods for attachment of thiol specific probes to the 3'-ends of synthetic oligodeoxyribonucleotides

Methodology is described for the synthesis of DNA oligomers containing a free 3'-thiol group which can be selectively crosslinked with a wide variety of probes. This chemistry is compatible with both phosphotriester and phosphoramidite solid phase chemistry. Moreover, the sulphydryl group is introduced into the 3'-nucleoside solid support linkage prior to oligonucleotide synthesis. Consequently, no additional coupling steps are required after oligonucleotide synthesis, and isolation of the 3'-thiol oligonucleotide requires only one additional deprotection step. Cross-linking of the thiol-containing oligonucleotide to a fluorescent probe was carried out with high selectivity, in high yield, and under mild conditions.

Altered vitamin E status in Niemann-Pick type C disease

Vitamin E (α-tocopherol) is the major lipid-soluble antioxidant in many species. Niemann-Pick type C (NPC) disease is a lysosomal storage disorder caused by mutations in the NPC1 or NPC2 gene, which regulates lipid transport through the endocytic pathway. NPC disease is characterized by massive intracellular accumulation of unesterified cholesterol and other lipids in lysosomal vesicles. We examined the roles that NPC1/2 proteins play in the intracellular trafficking of tocopherol. Reduction of NPC1 or NPC2 expression or function in cultured cells caused a marked lysosomal accumulation of vitamin E in cultured cells. In vivo, tocopherol significantly accumulated in murine Npc1-null and Npc2-null livers, Npc2-null cerebella, and Npc1-null cerebral cortices. Plasma tocopherol levels were within the normal range in Npc1-null and Npc2-null mice, and in plasma samples from human NPC patients. The binding affinity of tocopherol to the purified sterol-binding domain of NPC1 and to purified NPC2 was significantly weaker than that of cholesterol (measurements kindly performed by R. Infante, University of Texas Southwestern Medical Center, Dallas, TX). Taken together, our observations indicate that functionality of NPC1/2 proteins is necessary for proper bioavailability of vitamin E and that the NPC pathology might involve tissue-specific perturbations of vitamin E status.

Association of built environment characteristics with adiposity and glycaemic measures

OBJECTIVE

This study examined the cross-sectional and longitudinal relationships of built environment characteristics with adiposity and glycaemic measures.

METHOD

Longitudinal study sample consisted of 4,010 Framingham Heart Study Offspring (baseline: 1998-2001; follow-up: 2005-2008) and Generation Three (baseline: 2002-2005; follow-up: 2008-2011) participants (54.8% women, baseline mean age 48.6 years). Built environment characteristics (intersection density, greenspace, recreation land and food stores) at baseline were collected. Adiposity and glycaemic measures (body mass index [BMI], waist circumference, abdominal subcutaneous and visceral adipose tissue, and fasting plasma glucose) at baseline and changes during 6.4-year follow-up were measured.

RESULTS

In cross-sectional models, higher intersection density and food store density (total food stores, fast food restaurants and supermarkets) were linearly associated with higher BMI (all p < 0.05). Higher greenspace was associated with lower BMI, waist circumference, fasting plasma glucose, prevalent obesity and prevalent diabetes (all p < 0.05). Longitudinally, higher intersection density and food store density, and lower greenspace were associated with smaller increases in abdominal visceral adipose tissue (all p < 0.05). Higher densities of intersections, fast food restaurants and supermarkets were associated with smaller increases in fasting plasma glucose (all p < 0.05).

CONCLUSIONS

Collectively, built environment characteristics are associated with adiposity and glycaemic traits, suggesting the potential mechanisms by which built environment influences cardiometabolic health.

The genomic structure of the gene defective in Usher syndrome type Ib (MYO7A)

Usher syndrome type Ib is a recessive autosomal disorder manifested by congenital deafness, vestibular dysfunction, and progressive retinal degeneration. Mutations in the human myosin VIIa gene (MYO7A) have been reported to cause Usher type Ib. Here we report the genomic organization of MYO7A. An STS content map was determined to discover the YAC clones that would cover the critical region for Usher syndrome type Ib. Three of the YACs (802A5, 966D6, and 965F10) were subcloned into cosmids and used to assemble a preliminary cosmid contig of the critical region. Part of the gene encoding human myosin VIIa was found in the preliminary cosmid contig. A cosmid, P1, PAC, and long PCR contig that contained the entire MYO7A gene was assembled. Primers were designed from the composite cDNA sequence and used to detect intron-exon junctions by directly sequencing cosmid, P1, PAC, and genomic PCR DNA. Alternatively spliced products were transcribed from the MYO7A gene: the largest transcript (7.4 kb) contains 49 exons. The MYO7A gene is relatively large, spanning approximately 120 kb of genomic DNA on chromosome 11q13.

Myosin VIIA mutation screening in 189 Usher syndrome type 1 patients

Usher syndrome type 1b (USH1B) is an autosomal recessive disorder characterized by congenital profound hearing loss, vestibular abnormalities, and retinitis pigmentosa. The disorder has recently been shown to be caused by mutations in the myosin VIIa gene (MYO7A) located on 11q14. In the current study, a panel of 189 genetically independent Usher I cases were screened for the presence of mutations in the N-terminal coding portion of the motor domain of MYO7A by heteroduplex analysis of 14 exons. Twenty-three mutations were found segregating with the disease in 20 families. Of the 23 mutations, 13 were unique, and 2 of the 13 unique mutations (Arg212His and Arg212Cys) accounted for the greatest percentage of observed mutant alleles (8/23, 31%). Six of the 13 mutations caused premature stop codons, 6 caused changes in the amino acid sequence of the myosin VIIa protein, and 1 resulted in a splicing defect. Three patients were homozygotes or compound heterozygotes for mutant alleles; these three cases were Tyr333Stop/Tyr333Stop, Arg212His-Arg302His/Arg212His-Arg302His, and IVS13nt-8c-->g/Glu450Gln. All the other USH1B mutations observed were simple heterozygotes, and it is presumed that the mutation on the other allele is present in the unscreened regions of the gene. None of the mutations reported here were observed in 96 unrelated control samples, although several polymorphisms were detected. These results add three patients to single case reported previously where mutations have been found in both alleles and raises the total number of unique mutations in MYO7A to 16.