Cell Signalling

Shark livers are considered as an important raw material providing a quality fish oil. It has been reported to aid white — blood-cell production and act as an active ingredient in hemorrhoid treatments. It is also reported that liver oil as a good supplement of vitamin A and poly-unsaturated fatty acids which are important to the development of brain cells in human. Freshness of livers is very important to extract better quality oil. In Sri Lanka, the annual shark production amounts to 8000t, however the quality of livers collected from landing sites has not being measured yet. Present study was conducted to evaluate the quality of silky (Charcarninus fakiformis) shark livers available in Negombo and Beruwala landing sites in the West Coast of Sri Lanka and also to study the relationship between organoleptic and bio-chemical correlation on freshness of shark livers. Liver samples which were collected from landing sites in the West coast of Sri Lanka, were evaluated for external and ...

Mojzsis et al. 1,2 reported the carbon-isotope composition of carbonaceous inclusions in grains of apatite from sediment sequences of Akilia island, southwest Greenland, that are more than 3,850 million years (Myr) old. The Ȏ 13 C values measured by Mojzsis et al. 1 led them to conclude that these carbonaceous materials are evidence of early life 3,850 Myr ago. But if other isotopes (U-Pb and Pb-Pb) are used, the apatites are estimated at just 1,504DŽ336 (2Ȝ) and 1,459DŽ160 (2Ȝ) Myr old. This value is consistent with measurements of 1,600-1,700 Myr for Rb-Sr mineral isochrons on biotites 3 and 1,670 Myr for K-Ar muscovite 4 from Amitsog gneiss in the region. We conclude that, about 1,500 Myr ago, these apatites in Akilia island experienced a metamorphic event of about 600 °C (estimated by the closure temperature of the U-Pb system 5,6). Mojzsis et al. 1 measured the carbonisotope composition of graphite inclusions in grains of apatite in banded-iron formations (BIFs) from Akilia island. Their observed Ȏ 13 C values ranged from ǁ20 per mil (‰) to ǁ50‰, using a PDB standard, indicating a biogenic origin. The BIFs are older than 3,850 Myr (ref. 2), but the age of the apatite housing the graphite material was not determined. Here we present measurements of the U-Pb age of apatites from closely related samples. We cast the sample chip of the Akilia BIFs (approximately 1 ǂ1 cm) into epoxyresin disks with several grains of standard apatite and polished them until they were exposed through their mid-sections. The sample apatites are about 20-30 Ȗm in size and show similar texture to those reported by Mojzsis et al. 1. We focused a primary beam of about 2.5 nA O 2 ǁ to sputter an area of apatites 20 Ȗm in diameter, and extracted the positive secondary ions using 10 kV. We found no isobaric interferences in the mass range over 204 Pb and 208 Pb at a mass resolution of 5,800. We obtained the 238 U/ 206 Pb ratios from the observed 238 U + / 206 Pb + ratios by calibration using an empirical quadratic relationship between 206

The canonical role of messenger RNA (mRNA) is to deliver protein-coding information to sites of protein synthesis. However, given that microRNAs bind to RNAs, we hypothesized that RNAs possess a biological role in cancer cells that relies upon their ability to compete for microRNA binding and is independent of their protein-coding function. As a paradigm for the protein-codingindependent role of RNAs, we describe the functional relationship between the mRNAs produced by the PTEN tumour suppressor gene and its pseudogene (PTENP1) and the critical consequences of this interaction. We find that PTENP1 is biologically active as determined by its ability to regulate cellular levels of PTEN, and that it can exert a growth-suppressive role. We also show that PTENP1 locus is selectively lost in human cancer. We extend our analysis to other cancerrelated genes that possess pseudogenes, such as oncogenic KRAS. Further, we demonstrate that the transcripts of protein coding genes such as PTEN are also biologically active. Together, these findings attribute a novel biological role to expressed pseudogenes, as they can regulate coding gene expression, and reveal a non-coding function for mRNAs. In human cancers, monoallelic mutation of PTEN without loss or mutation of the second allele is prevalent at presentation, while complete loss is observed at low frequencies with the exception of advanced cancers 1. In mouse models, heterozygosity for Pten leads to multiple cancers 2 , and serial reduction of Pten dosage has critical consequences for the incidence and severity of epithelial cancers 3,4 , together suggesting that PTEN is a functionally haploinsufficient tumour suppressor gene. The identification and validation of Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:

Objective: Classical neuronal signalling molecules such as substance P and glutamate have been identified in cartilage and have roles in regulation of chondrocyte function. This study looks at expression and activity of the ionotropic glutamate NMDA (N-methyl-D-aspartic acid) receptor (NMDAR) in human osteoarthritic (OA) chondrocytes. Method: Chondrocytes were obtained from human knee joint arthroplasty specimens. NMDAR subunits and PSD-95 (postsynaptic density protein 95) expression were analysed by reverse transcription-polymerase chain reaction and Western blotting. Activity of NMDAR was assayed by radioactive calcium 45 uptake and changes in membrane potential in the presence and absence of NMDA and NMDAR antagonists and blockade of cell membrane ion channels. Results: NMDAR 1, 2A, 2B and PSD-95 were detected in human OA chondrocytes whereas NR2B was absent from normal chondrocytes. NMDA induced calcium flux into OA chondrocytes and cell membrane depolarisation. These responses were blocked by NMDAR antagonists, removal of extracellular calcium, inhibition of nNOS (neuronal nitric oxide synthase) activity and uncoupling of NMDAR from PSD-95. Blockade of sodium channels by tetrodotoxin resulted in NMDA-induced membrane hyperpolarisation which was, in turn inhibited by apamin, a blocker of SK channels. NMDA-induced changes in cell membrane potential were not affected by L-type and stretch activated calcium channel inhibitors. Conclusions: Human OA and normal articular chondrocytes differ in the expression of NMDAR subunits. In OA chondrocytes NMDAR signalling requires extracellular calcium, association with PSD-95, and nNOS activity. Downstream signalling results in activation of tetrodotoxin sensitive sodium channels and SK channels, a response that differs from that of normal chondrocytes suggesting altered activity of NMDAR in OA.

Stathmin is a highly conserved cytosolic phosphoprotein that destabilizes microtubules. Stathmin, which has been proposed as a relay protein integrating diverse cell signalling pathways, acts in vitro as a tubulin-sequestering protein, and its activity is dramatically reduced by phosphorylation. Interestingly, stathmin expression and phosphorylation are regulated during the control of cell growth and differentiation, and there is much evidence suggesting that in vivo stathmin plays a role in the control of microtubule dynamics during mitosis. Stathmin may thus be considered as one of the key regulators of cell division. We examined 50 human primary breast tumours for stathmin mRNA and protein expression and screened for abnormalities in the chromosome region harbouring the stathmin gene. Overexpression of stathmin was found in 15 tumours (30%). At the present stage, no clear correlation emerged between stathmin expression and several prognosis markers. Interestingly, perfect matching was observed between stathmin mRNA overexpression, protein overexpression and strong staining for stathmin on paraffin-embedded tumour sections when specimens were available. Furthermore, a tentative link between loss of heterozygosity (LOH) in the 1 p32-1 pter region and stathmin overexpression was observed. Our results suggest that stathmin might play a role in breast carcinogenesis and that stathmin-overexpressing tumours may represent a new subtype of breast cancer.

Neuromotor prostheses (NMPs) aim to replace or restore lost motor functions in paralysed humans by routeing movement-related signals from the brain, around damaged parts of the nervous system, to external effectors. To translate preclinical results from intact animals to a clinically useful NMP, movement signals must persist in cortex after spinal cord injury and be engaged by movement intent when sensory inputs and limb movement are long absent. Furthermore, NMPs would require that intention-driven neuronal activity be converted into a control signal that enables useful tasks. Here we show initial results for a tetraplegic human (MN) using a pilot NMP. Neuronal ensemble activity recorded through a 96-microelectrode array implanted in primary motor cortex demonstrated that intended hand motion modulates cortical spiking patterns three years after spinal cord injury. Decoders were created, providing a 'neural cursor' with which MN opened simulated e-mail and operated devices such as a television, even while conversing. Furthermore, MN used neural control to open and close a prosthetic hand, and perform rudimentary actions with a multijointed robotic arm. These early results suggest that NMPs based upon intracortical neuronal ensemble spiking activity could provide a valuable new neurotechnology to restore independence for humans with paralysis.

Programmed cell death is a fundamental requirement for embryogenesis, organ metamorphosis and tissue homeostasis. In mammals, release of mitochondrial cytochrome c leads to the cytosolic assembly of the apoptosome-a caspase activation complex involving Apaf1 and caspase-9 that induces hallmarks of apoptosis. There are, however, mitochondrially regulated cell death pathways that are independent of Apaf1/caspase-9. We have previously cloned a molecule associated with programmed cell death called apoptosis-inducing factor (AIF). Like cytochrome c, AIF is localized to mitochondria and released in response to death stimuli. Here we show that genetic inactivation of AIF renders embryonic stem cells resistant to cell death after serum deprivation. Moreover, AIF is essential for programmed cell death during cavitation of embryoid bodies-the very first wave of cell death indispensable for mouse morphogenesis. AIF-dependent cell death displays structural features of apoptosis, and can be gene...

because there were more prolonged dry spells over the vegetation period. The probability of producing yields of less than 3.5 t ha ǁ1 in the 'with variability' scenario was nearly 0.50, compared with about 0.10 for the baseline and 'without variability' scenarios. Such changes in annual yield variability would make wheat a risky crop to grow in Spain and have important economic and social consequences. For the United Kingdom, changes in climate variability had little effect on either mean grain yield or its CV (Table 1). In contrast, Hulme et al. found no change in the range (and hence the variability) of simulated yields for these sites as a result of either multi-decadal natural or anthropogenic variability. The timescale of the imposed variability can therefore alter qualitatively whether or not variability has an effect. We conclude that it is important when assessing the impact of climate change to differentiate between natural climate variability and anthropogenic climate change, as highlighted by Hulme et al., but also to apply changes in climate variability at appropriate timescales.

well as through the large-field-gradient positions just above and below the crown-ether molecules. We have also made direct measurements of the ionic conductivity of the crown-ether salt and also of reference materials. We used an electron-blocking method, in which a compacted disk of the material under test was sandwiched between Li + /polyethylene oxide disks which were pressed onto Li metal electrodes. The ionic conductivity of (PEG)-Li(CF 3 SO 3), where PEG is polyethylene glycol, was measured to be 1:6 ϫ 10 Ϫ 6 S cm Ϫ 1 at 60 ЊC, in good agreement with literature values 15. We measured values, also at 60 ЊC, for a range of Ni(dmit) 2 salts: 3 ϫ 10 Ϫ 6 S cm Ϫ 1 for Li 0.6 (15-crown-5-ether) [Ni(dmit) 2 ] 2 ⋅H 2 O; 2 ϫ 10 Ϫ 8 S cm Ϫ 1 for (C 16 H 33) 2 (CH 3) 2 N[Ni(dmit) 2 ]; and 3 ϫ 10 Ϫ 7 S cm Ϫ 1 for (TPP)[Ni(dmit) 2 ] 3 , where TPP is tetraphenylphosphonium. Each measurement was made after the current reached its saturated value, typically between 30 and 60 minutes after application of the constant voltage. We have checked that there is no decomposition (for example, water loss) at 60 ЊC (by thermal gravimetry), and consider that the value of ionic conductivity for the crown-ether Li + salt indicates clearly that there is significant Li + mobility in this material at this temperature. We have measured significantly lower values in the (electronically insulating) tetra-alkyl ammonium salt and the (electronically conducting) tetraphenylphosphonium salt. We consider that the electron dynamics on the Ni(dmit) 2 chains are controlled by the dynamics of the Li + ions in the crown-ether columns. Above 250 K the Li + ions are mobile, and do not localize the conduction electrons on the Ni(dmit) 2 stacks, which therefore show metallic properties. Between 250 and 200 K the Li + ions become immobilized, and provide static coulombic pinning potentials for the conduction electrons on the Ni(dmit) 2 stacks, causing localization and the magnetic insulator properties evident in Figs 2 and 3. A metal-insulator transition driven by interaction between ions and electrons in this way is unusual, and the example that we have illustrated here may provide insights into transport properties of other mixed ionic/electronic conductors, such as the conjugated polymer blends recently used by Pei et al. 5 in electroluminescent diodes. The electron-transport system with ion channels that we describe here may allow for the design of electron-cation transport systems for use in active and selective ion transport. For example, a double carrier process could be realised in a redox gradient where the coupled parallel transport of electrons and alkali-metal cations takes place 16 .

TGR5, G protein-coupled receptor 19, is also known as G protein-coupled bile acid receptor 1. The single exon encodes a TGR5 protein composed of 330 amino acids with seven transmembrane domains. Although TGR5 is expressed in various tissues such as liver, nervous system, adipocytes, endocrine glands, gall bladder, muscles, and spinal cord, the expression level in these tissues is less than 1/10 of myeloid immune cells. Activation of TGR5 incur various signaling cascades depending on the responder cell type. For example, synthesis and secretion of bile acids, intestinal secretion and motility, energy expenditure, glucose homeostasis, and inflammation is regulated by TGR5 pathway. Although TGR5 has got much attention as a promising new target for metabolic disorders or inflammatory disorders, only deoxycholic acid was licensed for lipoma. Obeticholic acid was also licensed for cholangitis but it interacts with FXR in addition to TGR5. Recently, we showed that taurodexoycholic acid (TDCA) interacts with TGR5, reduces inflammation incurred by activation of neutrophils, increases number of myeloid derived suppressor cells and prolongs survival of mice under sepsis. TDCA changes DNA methylation pattern of chromosome, globally edit proteomes of skin cells, brain cells and myeloid cells in mice model for atopic dermatitis, Alzheimer disease and sepsis, respectively. In addition, inflammasomal activation was suppressed by down-regulating a purinergic receptor in TDCA-treated neutrophils. In addition, cAMP-PKA-NF-κB pathway was controlled by TDCA. Phase I clinical trials for atopic dermatitis using TDCA did not show significant adverse drug reactions. Taken together, TDCA might be a non-classical anti-inflammatory drug (NCAID) for various inflammatory disorders when activation of myeloid inflammatory cells are pathognomonic features.

There are several possible starting points for protein identification. But the most well-travelled route into proteomics starts with a sample in a 2D gel being fed into an electrophoresis machine. This is followed by either automatic or manual picking and excision of the protein spots of interest, which are then fed into a mass spectrometer (see 'Mix and match' , previous page). Celia Caulcott, who heads an effort by the UK's Biotechnology and Biological Sciences Research Council to develop new proteomics technologies, says that, despite a lot of R&D, traditional techniques for protein identification still stand. "The gels still seem to be the pre-eminent way people want to do things," she says. Beguiling techniques such as protein arrays, which could supplant gels if successful, have yet to prove they can be viable both scientifically and commercially, she says. Joakim Rodin, director for proteomics R&D at Amersham Biosciences, a biotechequipment company based in Uppsala, Sweden, agrees that the gel system, although not the easiest thing to work with, has yet to be supplanted. "It's still a lot of work running the gels," he says. But improvements in capacity, such as the company's Ettan Dalt II system, allows researchers to run up to 12 gels in parallel with more reproducibility and sensitivity. And the gels themselves have improved, Lab-on-a-CD systems from Gyros. Identifying spots on gels can be time consuming.

cology is rather like sex," according to science writer Michael Allaby. "Every new generation likes to think they were the first to discover it." Indeed, there is currently a sense of wide-eyed excitement surrounding the field as the latest generation gets to grips with its 'discovery'. And this time around, solutions to the environment's complicated problems are flowing from new combinations of scientific and professional talent. Today's wildlife biology, forestry or naturalresource group is as likely to include non-traditional posts such as environmental lawyers or mathematical modellers as more traditional roles such as geologists and telemetry specialists (see 'A non-traditional approach' , right). And positions now tend to draw on several such backgrounds. The term 'ecological engineer' , for example, would describe someone who plans and develops ecologically sensitive sites, "someone grounded in biological systems who also has a good sense of how things work", says Jason Taylor, education programme manager at the Ecological Society of America, a Washington-based professional society. The social sciences increasingly enter the ecological equation too, adds Thomas Rice, a soil scientist at California Polytechnic University in San Luis Obispo. Rice recalls a student who came to him with an undergraduate degree in sociology, then turned to modelling the environmental effects brought about by mega-cities. An increasing emphasis on building models for more environmental processes is causing some shortages: the

Experiments with a spontaneously transformed equine epithelial cell line showed that certain nucleotides increased intracellular free calcium ([Ca 2+ ] i) in cells plated on glass coverslips. The rank order of potency was ATP=UTP45-Br-UTP, whilst UDP and ADP were ineective. The response thus appears to be mediated by P2Y 2 receptors. 2 Nucleotides also increased short circuit current (I SC) in cells grown into epithelial monolayers and the rank order of potency was UDP4UTP45-Br-UTP4ATP4ADP. The increase in [Ca 2+ ] i and the rise in I SC thus have dierent pharmacological properties. Cross-desensitization experiments indicated that, as well as P2Y 2 receptors, the monolayer cultures express at least one additional receptor population that allowed nucleotides to increase I SC. 3 The UDP-evoked increase in I SC was essentially abolished in BAPTA-loaded epithelia suggesting that this response is dependent upon increased [Ca 2+ ] i. Moreover, experiments in which I SC and [Ca 2+ ] i were measured simultaneously showed that the UDP-and ADP-evoked increases in I SC were accompanied by increases in [Ca 2+ ] i. 4 When grown under conditions which favour the development of a polarized phenotype, these epithelial cells thus appear to express [Ca 2+ ] i-mobilizing receptors sensitive to UDP and ADP that are not present in non-polarized cells on coverslips.

gradient. Of course, genetic variation other than proteorhodopsin tuning is likely to in¯uence the ®tness of population variants along the depth gradient. Other genetic loci may also co-vary with tuned absorption maxima, indicating a depth-optimized adaptation for these other traits as well. Genomic approaches should provide a means to test such hypotheses. Proteorhodopsin-mediated phototrophic energy generation may have a signi®cant impact on carbon and energy¯ux in the ocean. Although it is not known whether proteorhodopsin-bearing bacteria ®x CO 2 , their ability to generate energy from light should reduce overall respiratory energy requirements, as has been suggested for aerobic, bacteriochlorophyll-containing marine bacteria 19. Bioenergetic calculations based on our data suggest that proteorhodopsin-based phototrophy could provide a large fraction of energy requirements for cell maintenance and reproduction. The widespread distribution and high abundance of SAR86 bacteria 5,10,20±22 , combined with the biophysical and genetic data that we report, indicate that proteorhodopsin phototrophy is a biologically signi®cant, globally distributed marine microbial process. M Methods Cell collection and membrane preparation Antarctic coastal waters were collected off Palmer Station (64.48 S, 64.08 W), Anvers Island, Antarctic Peninsula, in August 1996 (ref. 23). Hawaiian HOT station (22.48 N, 158.08 W) waters were collected on 17 March 1998. Cell membranes were prepared from picoplankton cells concentrated from surface seawater (700 l) collected in early winter 2000, roughly 26 miles offshore from Moss Landing, California (36.78 N, 122.48 W). Water samples were pre®ltered through a GF/A glass-®bre ®lter (approximate particle size , 0.6 mm) to remove the larger eukaryotic phytoplankton cells. We concentrated the ®ltrate by tangential¯ow ®ltration 10 and prepared the membranes 24 as described. Aliquots of the cell preparation were ®xed in 3.7% formalin for subsequent¯uorescence in situ hybridization and taxon-speci®c cell quanti®cation. Fluorescence in situ hybridization BAC clones 31A08 and 27G05 (ref. 10) were used as templates to generate SAR86-speci®c polyribonucleotide probes targeted to large-subunit ribosomal RNA. We prepared uorescently labelled polyribonucleotide probes that targeted a variable region of large subunit rRNA by in vitro transcription (M. Leclerc et al., manuscript in preparation), and carried out subsequent whole-cell hybridization assays as described 25. The percentage of SAR86-type cells relative to total 49,6-diamidino-2-phenylindole dihydrochloride (DAPI)-stained cells was calculated as described 25. Spectroscopy One-half of the cell-membrane suspension (corresponding to 350 l of seawater) was suspended in 2 ml of 100 mM sodium phosphate buffer, pH 7.0. Absorption spectra were measured on an Aminco DW2000 UV-visible absorption spectrophotometer (SLM; Urbana, IL). Flash-induced absorption transients in the millisecond to seconds time domain were acquired on a digital oscilloscope (Nicolet, Integra20) after a Nd-YAG laser ash (532 nm, 6-ns pulse duration, 40 mJ; Continuum, Surelight I) in a laboratory-constructed¯ash-photolysis system as described 6. Each transient was obtained by averaging 64 acquisition sweeps collected at 30-s intervals at various wavelengths between 360 and 680 nm. We performed kinetic analyses with the program IGOR Pro, v3.1 (WaveMetrics, Lake Oswego, OR).

quibble about minor inaccuracies, and there are more than a few typographical errors. But all in all, Journey From the Center of the Sun is a fine book. Solar physics is a vibrant field of research, with many spacebased and ground-based observatories either operating or under construction, and many theoretical ideas being fleshed out with high-powered numerical simulations. Zirker has written an entertaining and educational survey of the current state of knowledge of our all-important neighbour that sits at the centre of the Solar System. I

spin-polarized because the same number of spin-up and spin-down electrons move in the same direction with the same velocity. In the case of inelastic scattering the current may be polarized. The uniformity of the spin polarization in space is preserved during the scattering processes. Therefore, the spin-galvanic effect differs from surface currents induced by inhomogeneous spin orientation 25. It also differs from other experiments where the spin current is caused by gradients of potentials, concentrations and so on, like the spin-voltaic effect 26,27 and the photo-voltaic effect, which occur in inhomogeneous samples, and like the 'paramagnetic metal-ferromagnet' junction or p-n junctions. When considering spintronic devices involving heterojunctions, spingalvanic current must be taken into account.

Cytokines of the tumor necrosis factor (TNF) family regulate inflammation and immunity, and a subset of this family can also induce cell death in a context-dependent manner. Although TNFa is cytotoxic to certain tumor cell lines, it induces apoptosis in normal cells only when NFjB signaling is blocked. Here we show that the matricellular protein CCN1/CYR61 can unmask the cytotoxic potential of TNFa without perturbation of NFjB signaling or de novo protein synthesis, leading to rapid apoptosis in the otherwise resistant primary human fibroblasts. CCN1 acts through binding to integrins a v b 5 , a 6 b 1 , and syndecan-4, triggering the generation of reactive oxygen species (ROS) through a Rac1-dependent mechanism via 5-lipoxygenase and the mitochondria, leading to the biphasic activation of JNK necessary for apoptosis. Mice with the genomic Ccn1 locus replaced with an apoptosis-defective Ccn1 allele are substantially resistant to TNFa-induced apoptosis in vivo. These results indicate that CCN1 may act as a physiologic regulator of TNFa cytotoxicity, providing the contextual cues from the extracellular matrix for TNFa-mediated cell death.

Sir-The recent UN World Conference on Disaster Reduction in Kobe, Japan, was dominated by discussion of the Indian Ocean tsunami ("Solo efforts hamper tsunami warning system" Nature 433, 343; 2005). However, we must not forget the extreme vulnerability of small islands and low-lying coastal areas to sea-level rise caused by climate change. The accumulation of greenhouse gases in the atmosphere during the past few hundred years is likely to result in a sealevel rise of up to half a metre, possibly more, by 2050 (R. J. Nicholls & J. A. Lowe, Glob. Environ. Change, in the press). Many of the affected countries do not have the resources to adopt protective measures such as sea walls and embankments, nor can they afford insurance. By the end of the century, millions are likely to have been driven from their homes by sea-level rise. One of the ironies of climate change is that, although wealthy countries are

Acknowledgements. We thank the ESRF and SRS Daresbury for data collection facilities; the EMBL outstation, Grenoble, for use of an image plate detector; M.L.D. Page for expert advice; R. Bryan and R. Esnouf for computing; K. Harlos for help with in-house data collection; F. Armstrong and J. Hirst for providing electrochemically reduced methyl viologen. This work was supported by MRC, BBSRC and EU-BIOTECH. The Oxford Centre for Molecular Sciences is funded jointly by BBSRC, EPSRC and MRC. N.F.W.S. was supported by a Wellcome Trust prize studentship. V.F. is a Royal Society university research fellow.