SLC2A9 is a newly identified urate transporter influencing serum urate concentration, urate excretion and gout

Uric acid is the end product of purine metabolism in humans and great apes, which have lost hepatic uricase activity, leading to uniquely high serum uric acid concentrations (200-500 microM) compared with other mammals (3-120 microM). About 70% of daily urate disposal occurs via the kidneys, and in 5-25% of the human population, impaired renal excretion leads to hyperuricemia. About 10% of people with hyperuricemia develop gout, an inflammatory arthritis that results from deposition of monosodium urate crystals in the joint. We have identified genetic variants within a transporter gene, SLC2A9, that explain 1.7-5.3% of the variance in serum uric acid concentrations, following a genome-wide association scan in a Croatian population sample. SLC2A9 variants were also associated with low fractional excretion of uric acid and/or gout in UK, Croatian and German population samples. SLC2A9 is a known fructose transporter, and we now show that it has strong uric acid transport activity in Xenopus laevis oocytes.     

A complementary transposon tool kit for Drosophila melanogaster using P and piggyBac

With the availability of complete genome sequence for Drosophila melanogaster, one of the next strategic goals for fly researchers is a complete gene knockout collection. The P-element transposon, the workhorse of D. melanogaster molecular genetics, has a pronounced nonrandom insertion spectrum. It has been estimated that 87% saturation of the approximately 13,500-gene complement of D. melanogaster might require generating and analyzing up to 150,000 insertions. We describe specific improvements to the lepidopteran transposon piggyBac and the P element that enabled us to tag and disrupt genes in D. melanogaster more efficiently. We generated over 29,000 inserts resulting in 53% gene saturation and a more diverse collection of phenotypically stronger insertional alleles. We found that piggyBac has distinct global and local gene-tagging behavior from that of P elements. Notably, piggyBac excisions from the germ line are nearly always precise, piggyBac does not share chromosomal hotspots associated with P and piggyBac is more effective at gene disruption because it lacks the P bias for insertion in 5' regulatory sequences.     

An endoribonuclease-prepared siRNA screen in human cells identifies genes essential for cell division

RNA interference (RNAi) is an evolutionarily conserved defence mechanism whereby genes are specifically silenced through degradation of messenger RNAs; this process is mediated by homologous double-stranded (ds)RNA molecules. In invertebrates, long dsRNAs have been used for genome-wide screens and have provided insights into gene functions. Because long dsRNA triggers a nonspecific interferon response in many vertebrates, short interfering (si)RNA or short hairpin (sh)RNAs must be used for these organisms to ensure specific gene silencing. Here we report the generation of a genome-scale library of endoribonuclease-prepared short interfering (esi)RNAs from a sequence-verified complementary DNA collection representing 15,497 human genes. We used 5,305 esiRNAs from this library to screen for genes required for cell division in HeLa cells. Using a primary high-throughput cell viability screen followed by a secondary high content videomicroscopy assay, we identified 37 genes required for cell division. These include several splicing factors for which knockdown generates mitotic spindle defects. In addition, a putative nuclear-export terminator was found to speed up cell proliferation and mitotic progression after knockdown. Thus, our study uncovers new aspects of cell division and establishes esiRNA as a versatile approach for genomic RNAi screens in mammalian cells.     

Algal populations in Bottle Hollow Reservoir, Duchesne County, Utah

Bottle Hollow Reservoir contains a diverse algal flora. A total of 289 taxa was observed, 227 of which were diatoms. Both littoral and planktonic communities had high diatom diversity. During summer months filamentous Chlorophvta were diverse and high in biomass in the littoral zone. Phytoplankton collections in Bottle Hollow Reservoir were dominated by four species: Asterionella formosa, Cyclotella comta, Dinobryon divergens, and Fragilaria crotonensis. Plankton samples contained mostly small diatoms in early spring, with larger algae succeeding these as the summer progressed. No blue - green algae were important in this succession. Two peak production periods were observed, one in the fall and one in the spring. Bottle Hollow Reservoir appears to be a healthy mesotrophic system based on the evidences of moderately high algal diversity, insignificance of blue-green algae, and the presence of a suite of diatom species indicative of mesotrophic conditions.     

Isolation of peptides blocking the function of anti-apoptotic Livin protein

Livin (ML-IAP) is a cancer-associated member of the inhibitor of apoptosis protein (IAP) family. By yeast two-hybrid screening of a randomized peptide expression library, we isolated short linear peptides that specifically bind to Livin, but not to other IAPs. Intracellular expression of the peptides sensitized livin-expressing cancer cells toward different pro-apoptotic stimuli. The bioactive peptides neither showed sequence homologies to Smac-derived IAP inhibitors, nor did they interfere with the binding of Livin to Smac. Intracellular expression of the peptides did not affect the levels or the subcellular distribution of Livin. Growth of livin-expressing tumor cells was inhibited in colony formation assays by the Livin-targeting peptides. These findings provide evidence that the targeted inhibition of Livin by peptides represents a viable approach for the apoptotic sensitization and growth inhibition of tumor cells. The inhibitory peptides isolated here could form a novel basis for the development of therapeutically useful Livin inhibitors.     

Activation by contact with glass and the action of thrombin

Zusammenfassung Thrombin in kleinen Konzentrationen beschleunigt den Verlauf des Thromboplastin-Differenzierungs (screening)-Tests, unabhängig davon, ob das Plasma vorher durch Kontakt aktiviert wurde oder nicht. Die Wirkung des Thrombins zeigt sich jedoch deutlicher bei aktiviertem Plasma. Die Thrombinzeit des aktivierten Plasmas ist kürzer als die von inaktivem Plasma.     

Electronic transport in nanometre-scale silicon-on-insulator membranes

The widely used 'silicon-on-insulator' (SOI) system consists of a layer of single-crystalline silicon supported on a silicon dioxide substrate. When this silicon layer (the template layer) is very thin, the assumption that an effectively infinite number of atoms contributes to its physical properties no longer applies, and new electronic, mechanical and thermodynamic phenomena arise, distinct from those of bulk silicon. The development of unusual electronic properties with decreasing layer thickness is particularly important for silicon microelectronic devices, in which (001)-oriented SOI is often used. Here we show--using scanning tunnelling microscopy, electronic transport measurements, and theory--that electronic conduction in thin SOI(001) is determined not by bulk dopants but by the interaction of surface or interface electronic energy levels with the 'bulk' band structure of the thin silicon template layer. This interaction enables high-mobility carrier conduction in nanometre-scale SOI; conduction in even the thinnest membranes or layers of Si(001) is therefore possible, independent of any considerations of bulk doping, provided that the proper surface or interface states are available to enable the thermal excitation of 'bulk' carriers in the silicon layer.     

The grapevine genome sequence suggests ancestral hexaploidization in major angiosperm phyla

The analysis of the first plant genomes provided unexpected evidence for genome duplication events in species that had previously been considered as true diploids on the basis of their genetics. These polyploidization events may have had important consequences in plant evolution, in particular for species radiation and adaptation and for the modulation of functional capacities. Here we report a high-quality draft of the genome sequence of grapevine (Vitis vinifera) obtained from a highly homozygous genotype. The draft sequence of the grapevine genome is the fourth one produced so far for flowering plants, the second for a woody species and the first for a fruit crop (cultivated for both fruit and beverage). Grapevine was selected because of its important place in the cultural heritage of humanity beginning during the Neolithic period. Several large expansions of gene families with roles in aromatic features are observed. The grapevine genome has not undergone recent genome duplication, thus enabling the discovery of ancestral traits and features of the genetic organization of flowering plants. This analysis reveals the contribution of three ancestral genomes to the grapevine haploid content. This ancestral arrangement is common to many dicotyledonous plants but is absent from the genome of rice, which is a monocotyledon. Furthermore, we explain the chronology of previously described whole-genome duplication events in the evolution of flowering plants.     

New records of diatoms from Blue Lake Warm Spring, Tooele County, Utah

Blue Lake Warm Spring in Tooele County, Utah, contains a rich diatom flora with a significant number of taxa that are unusual in this region. We have identified a total of 136 taxa in our samples from this locality, several of which are new records for Utah and North America.