Locus-Specific Ribosomal RNA Gene Silencing in Nucleolar Dominance

The silencing of one parental set of rRNA genes in a genetic hybrid is an epigenetic phenomenon known as nucleolar dominance. We showed previously that silencing is restricted to the nucleolus organizer regions (NORs), the loci where rRNA genes are tandemly arrayed, and does not spread to or from neighboring protein-coding genes. One hypothesis is that nucleolar dominance is the net result of hundreds of silencing events acting one rRNA gene at a time. A prediction of this hypothesis is that rRNA gene silencing should occur independent of chromosomal location. An alternative hypothesis is that the regulatory unit in nucleolar dominance is the NOR, rather than each individual rRNA gene, in which case NOR localization may be essential for rRNA gene silencing. To test these alternative hypotheses, we examined the fates of rRNA transgenes integrated at ectopic locations. The transgenes were accurately transcribed in all independent transgenic Arabidopsis thaliana lines tested, indicating that NOR localization is not required for rRNA gene expression. Upon crossing the transgenic A. thaliana lines as ovule parents with A. lyrata to form F1 hybrids, a new system for the study of nucleolar dominance, the endogenous rRNA genes located within the A. thaliana NORs are silenced. However, rRNA transgenes escaped silencing in multiple independent hybrids. Collectively, our data suggest that rRNA gene activation can occur in a gene-autonomous fashion, independent of chromosomal location, whereas rRNA gene silencing in nucleolar dominance is locus-dependent

Partnering Universities and Companies in Russia: Effects of New Government Initiative

The paper presents the results of 2-year survey conducted in 2011-2012 among Russian universities and companies who jointly implement R&D projects aimed at development of high-tech manufacturing. The joint projects represent a new government instrument to stimulate the development of linkages between universities and companies by giving matching grants for R&D to companies with obligation to order R&D to a university-partner. The objectives of the survey included analysis of motivation for cooperation both from side of universities and companies; primary effects and side-effects of such initiative; changes that may be introduced to the government regulations concerning matching grants. Total 38 teams were surveyed. Our findings show that major motivations from side of universities were access to new practical research tasks from companies, selection of most competitive teams of researchers capable to work with companies, and strengthening reputation in business environment. Companies were interested in getting government funding in order to solve their technological problems; to strengthen, due cooperation with universities, their research capacity, and to use modern research infrastructure located at universities. The analysis allowed identification of the major effects of the matching grants mechanism. They included: strengthening of university orientation towards solving practical tasks which are of interest to business; institutionalization of relations between universities and business in the sphere of innovation activity; broadening of research cooperation and the formation of research consortiums; harmonization of research and educational tasks in universities, and orientation of the parties towards continuing cooperation in the innovation sphere

The effects of light intensity and algae-induced turbidity on feeding behaviour of larval striped trumpeter

Striped trumpeter larvae reared in algal cell-induced turbid water (greenwater) fed equally well in clearwater in a light intensity range of 1–10 mol s1 m2, when evaluated in terms of both the proportion of larvae feeding and larval feeding intensity. An ontogenetic improvement in photopic visual sensitivity of larvae was indicated by improved feeding at 0·1 mol s1 m2, from 265% of larvae feeding and 0·0270·005 rotifers consumed per feeding larva min1 on day 8, to 962% and 0·2210·007 rotifers consumed larva1 min1 on day 23 post-hatching. Algal cell-induced turbidity was shown to reduce incident irradiance with depth, indicated by increasing coefficients of attenuation (1·4–33·1) with increasing cell densities (0–2106 cells ml1), though light intensities in the feeding experiment test chambers, at the algal cell densities tested, were within the optimal range for feeding (1–10 mol s1 m2). Algae-induced turbidity had different effects on larval feeding response dependent upon the previous visual environment of the larvae. Young larvae (day 9 post-hatching) reared in clearwater showed decreased feeding capabilities with increasing turbidity, from 981% feeding and 0·1530·022 rotifers consumed larva1 min1 in clearwater to 6110% feeding and 0·0420·004 rotifers consumed larva1 min1 at 56 NTU, while older clearwater reared larvae fed well at all turbidities tested. Likewise, greenwater reared larvae had increased feeding capabilities in the highest algal cell densities tested (32 and 66 NTU) compared with those in low algal cell density (6 NTU), and clearwater (0·7 NTU) to which they were naïve