Unusual activity of the Sun during recent decades compared to the previous 11,000 years

Direct observations of sunspot numbers are available for the past four centuries, but longer time series are required, for example, for the identification of a possible solar influence on climate and for testing models of the solar dynamo. Here we report a reconstruction of the sunspot number covering the past 11,400 years, based on dendrochronologically dated radiocarbon concentrations. We combine physics-based models for each of the processes connecting the radiocarbon concentration with sunspot number. According to our reconstruction, the level of solar activity during the past 70 years is exceptional, and the previous period of equally high activity occurred more than 8,000 years ago. We find that during the past 11,400 years the Sun spent only of the order of 10% of the time at a similarly high level of magnetic activity and almost all of the earlier high-activity periods were shorter than the present episode. Although the rarity of the current episode of high average sunspot numbers may indicate that the Sun has contributed to the unusual climate change during the twentieth century, we point out that solar variability is unlikely to have been the dominant cause of the strong warming during the past three decades.     

Cadherin 23 is a component of the tip link in hair-cell stereocilia

Mechanoelectrical transduction, the conversion of mechanical force into electrochemical signals, underlies a range of sensory phenomena, including touch, hearing and balance. Hair cells of the vertebrate inner ear are specialized mechanosensors that transduce mechanical forces arising from sound waves and head movement to provide our senses of hearing and balance; however, the mechanotransduction channel of hair cells and the molecules that regulate channel activity have remained elusive. One molecule that might participate in mechanoelectrical transduction is cadherin 23 (CDH23), as mutations in its gene cause deafness and age-related hearing loss. Furthermore, CDH23 is large enough to be the tip link, the extracellular filament proposed to gate the mechanotransduction channel. Here we show that antibodies against CDH23 label the tip link, and that CDH23 has biochemical properties similar to those of the tip link. Moreover, CDH23 forms a complex with myosin-1c, the only known component of the mechanotransduction apparatus, suggesting that CDH23 and myosin-1c cooperate to regulate the activity of mechanically gated ion channels in hair cells.     

Structure of the molybdopterin-bound Cnx1G domain links molybdenum and copper metabolism

The molybdenum cofactor is part of the active site of all molybdenum-dependent enzymes, except nitrogenase. The molybdenum cofactor consists of molybdopterin, a phosphorylated pyranopterin, with an ene-dithiolate coordinating molybdenum. The same pyranopterin-based cofactor is involved in metal coordination of the homologous tungsten-containing enzymes found in archea. The molybdenum cofactor is synthesized by a highly conserved biosynthetic pathway. In plants, the multidomain protein Cnx1 catalyses the insertion of molybdenum into molybdopterin. The Cnx1 G domain (Cnx1G), whose crystal structure has been determined in its apo form, binds molybdopterin with high affinity and participates in the catalysis of molybdenum insertion. Here we present two high-resolution crystal structures of Cnx1G in complex with molybdopterin and with adenylated molybdopterin (molybdopterin-AMP), a mechanistically important intermediate. Molybdopterin-AMP is the reaction product of Cnx1G and is subsequently processed in a magnesium-dependent reaction by the amino-terminal E domain of Cnx1 to yield active molybdenum cofactor. The unexpected identification of copper bound to the molybdopterin dithiolate sulphurs in both structures, coupled with the observed copper inhibition of Cnx1G activity, provides a molecular link between molybdenum and copper metabolism.     

Expression of lysine-rich protein gene and analysis of lysine content in transgenic wheat

Expression vector pBPC102, which carries winged bean lysine-rich protein (wblrp) gene and dihydropicolinate synthase (DHDPS) gene, was transferred into hexaploid winter wheat cv. Jinghua No.l, Jing411, You899 and Yangnongl5 explants of immature inflorescence and immature embryos by particle bombardment. More than 100 transgenic plants were obtained under the selection of s-(2-aminoethyl)-L-cysteine (AEC). Confirmed transgenic plants of To and TI generation by PCR and PCR-Southern blotting analyses showed successful integration of wblrp gene into wheat genome. Analysis of transgenic plant lines of T2 by Northern dot-blotting showed good expression of wblrp gene in offspring seed. The content of free lysine in leaves, contents of bound lysine and total proteins in seeds of T2 transgenie wheat lines were determined and analyzed. Among 34 tested transgenic lines, levels of free lysine content in leaves of 9 transgenic lines are 2~3times higher than un-trans-formed wild-type cultivars. Among 17 analyzed transgenic lines, bound lysine content of 4 transgenic lines is more than 10% higher than that of wild-type cultivars. Our research suggests that introducing wblrp gene into wheat is an effective way to improve its nutrition quality.     

Differential distribution of TASK-1, TASK-2 and TASK-3 immunoreactivities in the rat and human cerebellum

In this work, the distributions of some acid-sensitive two-pore-domain K⁺ channels (TASK-1, TASK-2 and TASK-3) were investigated in the rat and human cerebellum. Astrocytes situated in rat cerebellar tissue sections were positive for TASK-2 channels. Purkinje cells were strongly stained and granule cells and astrocytes were moderately positive for TASK-3. Astrocytes isolated from the hippocampus, cerebellum and cochlear nucleus expressed TASK channels in a primary tissue culture. Our results suggest that TASK channel expression may be significant in the endoplasmic reticulum of the astrocytes. The human cerebellum showed weak TASK-2 immunolabelling. The pia mater, astrocytes, Purkinje and granule cells demonstrated strong TASK-1 and TASK-3 positivities. The TASK-3 labelling was stronger in general, but it was particularly intense in the Purkinje cells and pia mater.Received 25 February 2004; received after revision 19 April 2004; accepted 28 April 2004     

Identification and characterization of rod-derived cone viability factor

Retinitis pigmentosa is an untreatable, inherited retinal disease that leads to blindness. The disease initiates with the loss of night vision due to rod photoreceptor degeneration, followed by irreversible, progressive loss of cone photoreceptor. Cone loss is responsible for the main visual handicap, as cones are essential for day and high-acuity vision. Their loss is indirect, as most genes associated with retinitis pigmentosa are not expressed by these cells. We previously showed that factors secreted from rods are essential for cone viability. Here we identified one such trophic factor by expression cloning and named it rod-derived cone viability factor (RdCVF). RdCVF is a truncated thioredoxin-like protein specifically expressed by photoreceptors. The identification of this protein offers new treatment possibilities for retinitis pigmentosa.     

The role of increasing temperature variability in European summer heatwaves

Instrumental observations and reconstructions of global and hemispheric temperature evolution reveal a pronounced warming during the past approximately 150 years. One expression of this warming is the observed increase in the occurrence of heatwaves. Conceptually this increase is understood as a shift of the statistical distribution towards warmer temperatures, while changes in the width of the distribution are often considered small. Here we show that this framework fails to explain the record-breaking central European summer temperatures in 2003, although it is consistent with observations from previous years. We find that an event like that of summer 2003 is statistically extremely unlikely, even when the observed warming is taken into account. We propose that a regime with an increased variability of temperatures (in addition to increases in mean temperature) may be able to account for summer 2003. To test this proposal, we simulate possible future European climate with a regional climate model in a scenario with increased atmospheric greenhouse-gas concentrations, and find that temperature variability increases by up to 100%, with maximum changes in central and eastern Europe.