Imprinting control regions (ICRs) play a fundamental role in establishing and maintaining the non-random monoallelic expression of certain genes, via common regulatory elements such as non-coding RNAs and differentially methylated regions (DMRs) of DNA. We recently surveyed DNA methylation levels within four ICRs (H19-ICR, IGF2-DMR, KvDMR, and NESPAS-ICR) in whole-blood genomic DNA from 128 monozygotic (MZ) and 128 dizygotic (DZ) human twin pairs. Our analyses revealed high individual variation and intra-domain covariation in methylation levels across CpGs and emphasized the interaction between epigenetic variation and the underlying genetic sequence in a parent-of-origin fashion. Here, we extend our analysis to conduct two genome-wide screenings of single nucleotide polymorphisms (SNPs) underlying either intra-domain covariation or parent-of-origin-dependent association with methylation status at individual CpG sites located within ICRs. Although genome-wide significance was not surpassed due to sample size limitations, the most significantly associated SNPs found through multiple-trait genome-wide association (MQFAM) included the previously described rs10732516, which is located in the vicinity of the H19-ICR. Similarly, we identified an association between rs965808 and methylation status within the NESPAS-ICR. This SNP is positioned within an intronic region of the overlapping genes GNAS and GNAS-AS1, which are imprinted genes regulated by the NESPAS-ICR. Sixteen other SNPs located in regions apart from the analyzed regions displayed suggestive association with intra-domain methylation. Additionally, we identified 13 SNPs displaying parent-of-origin association with individual methylation sites through family-based association testing. In this exploratory study, we show the value and feasibility of using alternative GWAS approaches in the study of the interaction between epigenetic state and genetic sequence within imprinting regulatory domains. Despite the relatively small sample size, we identified a number of SNPs displaying suggestive association either in a domain-wide or in a parent-of-origin fashion. Nevertheless, these associations will require future experimental validation or replication in larger and independent samples.

In reviewing the tectonic features of a portion of Portuguese East Africa, south of the Zambezi, one of the present writers alone (2), and also in conjunction with Capt. R. C. Wilson (1), advanced the view that the surface topography had to some extent been affected by the same movements which were associated farther north with the Rift Zone period of Eastern Africa. This opinion was arrived at from the consideration of the physiography, the observation of definite faulting in places, especially in western Sheringoma on an extension of the Nyasa-Shire line, and also of volcanic occurrences elsewhere in significant positions.

The “bluestone” which is found in the central parts of some of the concretions associated with the large spiral bodies described by Mr. B. B. Woodward is found, on microscopical examination, to be a calcareous sandstone. Sabangular grains of quartz, averaging 0·04 mm. in diameter, constitute over 50 per cent of the rock, and are set in a cement of carbonates which have crystallized in plates very much as in the Fontainebleau sandstone. These plates are sometimes 3 cm. across, and give a characteristic lustre to the stone. The quartz-grains are evenly distributed through the plates of crystalline carbonate, and are so closely packed as to be almost in contact. It is easy to imagine that with the complete removal of the carbonates by solution there would remain a friable sandstone, very porous, but still occupying almost the same volume as the bluestone.

The alkaline volcanic rocks of the Lupata Gorge were described in 1915 by E. O. Teale and R. C. Wilson, and in 1922 F. P. Mennell showed that at the entrance to the gorge these rocks were preceded by a sheet of columnar rhyolite intercalated between two series of sediments, for which he proposed the name of the Upper and Lower Lupata Sandstones respectively; the Lower series rested on Karroo basalts, and these upon Karroo sandstones. In 1923, E. O. Teale and W. Campbell Smith gave a detailed petro-graphical description of certain of the alkaline lavas and of the intrusive olivine-nephelinite (nepheline-basalt) of Sena Hill on the south side of the Zambezi.

The peculiar garnetiferous rock occurring to the east of Loch Borolan seems to have been first noted by Dr. Callaway in 1883, and is described by Dr. Bonney in an appendix to Dr. Callaway's paper.

IN the course of a journey from El Obeid to Jebel Marra, in Darfur, Captain Hubert Lynes collected a number of the rocks from the volcano of Dereiba and from various other points on the route, shown in the map (Fig. 1). The rocks of this area have not been described hitherto. The following notes give a brief description of the nature of the country, with petrological details of the rocks collected.

Increasing MOSFET performance requires scaling, the systematic reduction in device dimensions. Tunneling leakage, however, provides an absolute scaling limit for SiO2of about 1.5 nm. Power limitations and device reliability are likely to pose softer limits slightly above 2 nm. We have investigated the use of high permittivity materials such as TiO2, ZrO2, and their silicates as potential replacements for SiO2. We have synthesized titanium nitrate (Ti(NO3)4or TN), zirconium nitrate (Zr(NO3)4or ZrN), and hafnium nitrate (Hf(NO3)4or HfN) as hydrogen and carbon free deposition precursors. Several problems arise in the use of these films including the formation of an amorphous low permittivity interfacial layer. For TiO2this layer is formed by silicon up diffusion. Surface nitridation retards the formation of the interfacial layer. We discuss the effects of both thermal and remote plasma surface nitridation treatments on the properties of the film stack. ZrO2and HfO2appear to form a thermal layer of silicon oxide between the high permittivity film and the silicon and have excess oxygen in the bulk of the film.

It is well known that some giant extragalactic star-forming regions contain WR stars. D'Odorico, Massey, Rosa and coworkers found many examples in nearby galaxies of giant HII regions whose spectra show that they contain WN, and occasionally, WC stars. The dwarf emission-line galaxies He 2–10 (Allen et al. 1976) and Tol 3 (Kunth & Sargent 1981) have a strong broad emission feature near HeII 4686Å; in the latter object ∼150 WN stars are required to explain the observed equivalent width.