C. elegans odour discrimination requires asymmetric diversity in olfactory neurons

Caenorhabditis elegans senses at least five attractive odours with a single pair of olfactory neurons, AWC, but can distinguish among these odours in behavioural assays. The two AWC neurons are structurally and functionally similar, but the G-protein-coupled receptor STR-2 is randomly expressed in either the left or the right AWC neuron, never in both. Here we describe the isolation of a mutant, ky542, with specific defects in odour discrimination and odour chemotaxis. ky542 is an allele of nsy-1, a neuronal symmetry, or Nsy, mutant in which STR-2 is expressed in both AWC neurons. Other Nsy mutants exhibit discrimination and olfactory defects like those of nsy-1 mutants. Laser ablation of the AWC neuron that does not express STR-2 (AWCOFF) recapitulates the behavioural phenotype of Nsy mutants, whereas laser ablation of the STR-2-expressing AWC neuron (AWCON) causes different chemotaxis defects. We propose that odour discrimination can be achieved by segregating the detection of different odours into distinct olfactory neurons or into unique combinations of olfactory neurons.     

Genome-wide association analysis identifies 20 loci that influence adult height

Adult height is a model polygenic trait, but there has been limited success in identifying the genes underlying its normal variation. To identify genetic variants influencing adult human height, we used genome-wide association data from 13,665 individuals and genotyped 39 variants in an additional 16,482 samples. We identified 20 variants associated with adult height (P < 5 x 10(-7), with 10 reaching P < 1 x 10(-10)). Combined, the 20 SNPs explain approximately 3% of height variation, with a approximately 5 cm difference between the 6.2% of people with 17 or fewer 'tall' alleles compared to the 5.5% with 27 or more 'tall' alleles. The loci we identified implicate genes in Hedgehog signaling (IHH, HHIP, PTCH1), extracellular matrix (EFEMP1, ADAMTSL3, ACAN) and cancer (CDK6, HMGA2, DLEU7) pathways, and provide new insights into human growth and developmental processes. Finally, our results provide insights into the genetic architecture of a classic quantitative trait.     

Cell-free synthesis and processing of multiple precursors to glucagon

Glucagon, a polypeptide hormone of 29 amino acids, is synthesized in the islets of Langerhans and immunoreactive forms of the molecule have been found in several tissues. Like many other polypeptide hormones, glucagon is synthesized via a larger precursor molecular, proglucagon; however, estimates of its size vary considerably and the biosynthetic relationship between some of the putative precursors and authentic secreted glucagon is unclear. Consequently it was of interest to investigate the primary translation product of glucagon mRNA to relate its size to that of previously described glucagon precursors. Here we provide evidence for three distinct immunoreactive preproglucagon molecules, two of which have an apparent molecular weight (MW) of approximately 16,000 (16K). Furthermore, when microsomal membranes were present during translation, the nascent 14K preproglucagon polypeptides were processed to proglucagon with a higher apparent MW of 15,000. In contrast, the nascent 16K preproglucagon was co-translationally processed to a slightly smaller polypeptide. The data indicate that the 14K and 16K preproglucagons undergo different types of post-translational modification.     

Resident Utah deer hunters' preferences for management options

A total of 3291 resident deer hunters returned questionnaires distributed at checking stations in fall 1989 and 1990 providing opinions and management data concerning the Utah rifle hunt. Hunters reported hunter crowding and too few big bucks as critical reasons for possibly choosing to quit deer hunting in Utah. Indeed, hunter age structure and measured satisfaction suggested a negative future trend in hunter participation. Results suggested the adoption of several hunter-preferred management options would increase satisfaction, motivation, and success.     

Survival and reproduction of translocated Eastern Wild Turkeys in a sparsely wooded landscape in northeastern South Dakota

We studied the survival and reproduction of a newly introduced population of Eastern Wild Turkeys ( Meleagris gallopavo silvestris ) during 1999 and 2000 to determine the adaptability of this subspecies to a minimally wooded (<10%) region located north of their recorded historic distribution in South Dakota. During 1999 and 2000, the South Dakota Department of Game, Fish and Parks (SDGFP) released 111 female and 25 male turkeys from Iowa and Kentucky onto a study area in northeastern South Dakota. We used radio telemetry to monitor survival and reproduction of the females for 2 years after their initial release. Annual survival for 71 females averaged 67%. Seasonal survival was lowest in fall and highest in winter. Mortality agents included avian and mammalian predators, haying equipment, automobiles, and unknown causes. Nesting rate for the 2 years averaged 93%, and renesting rate of turkeys with failed 1st-nest attempts averaged 45%. Nest success for all nests was 50%, and 62% of females attempting to nest each year were successful in at least 1 attempt. Predation was the primary cause of nest failure during both years. Overall, 72% of brooding females successfully raised ≥1 poult to 4 weeks post-hatch while individual poult survival to 4 weeks posthatch averaged 36%. Despite <10% woodland cover, Eastern Wild Turkeys appeared to thrive in a glacial escarpment topography north of their historic range in the northern plains.     

Resonant quantum transitions in trapped antihydrogen atoms

The hydrogen atom is one of the most important and influential model systems in modern physics. Attempts to understand its spectrum are inextricably linked to the early history and development of quantum mechanics. The hydrogen atom's stature lies in its simplicity and in the accuracy with which its spectrum can be measured and compared to theory. Today its spectrum remains a valuable tool for determining the values of fundamental constants and for challenging the limits of modern physics, including the validity of quantum electrodynamics and--by comparison with measurements on its antimatter counterpart, antihydrogen--the validity of CPT (charge conjugation, parity and time reversal) symmetry. Here we report spectroscopy of a pure antimatter atom, demonstrating resonant quantum transitions in antihydrogen. We have manipulated the internal spin state of antihydrogen atoms so as to induce magnetic resonance transitions between hyperfine levels of the positronic ground state. We used resonant microwave radiation to flip the spin of the positron in antihydrogen atoms that were magnetically trapped in the ALPHA apparatus. The spin flip causes trapped anti-atoms to be ejected from the trap. We look for evidence of resonant interaction by comparing the survival rate of trapped atoms irradiated with microwaves on-resonance to that of atoms subjected to microwaves that are off-resonance. In one variant of the experiment, we detect 23 atoms that survive in 110 trapping attempts with microwaves off-resonance (0.21 per attempt), and only two atoms that survive in 103 attempts with microwaves on-resonance (0.02 per attempt). We also describe the direct detection of the annihilation of antihydrogen atoms ejected by the microwaves.     

Palaeoclimatology: evidence for hot early oceans?

The oxygen isotopes in sedimentary cherts (siliceous sediments) have been used to argue that the Precambrian oceans were hot--with temperatures of up to 70 degrees C at 3.3 Gyr before present. Robert and Chaussidon measure silicon isotopes in cherts and arrive at a similar conclusion. We suggest here that both isotope trends may be caused by variations in seawater isotope composition, rather than in ocean temperatures. If so, then the climate of the early Earth may have been temperate, as it is today, and therefore more consistent with evidence for Precambrian glaciations and with constraints inferred from biological evolution.     

Bradykinin and nerve growth factor release the capsaicin receptor from PtdIns(4,5)P2-mediated inhibition.

Tissue injury generates endogenous factors that heighten our sense of pain by increasing the response of sensory nerve endings to noxious stimuli. Bradykinin and nerve growth factor (NGF) are two such pro-algesic agents that activate G-protein-coupled (BK2) and tyrosine kinase (TrkA) receptors, respectively, to stimulate phospholipase C (PLC) signalling pathways in primary afferent neurons. How these actions produce sensitization to physical or chemical stimuli has not been elucidated at the molecular level. Here, we show that bradykinin- or NGF-mediated potentiation of thermal sensitivity in vivo requires expression of VR1, a heat-activated ion channel on sensory neurons. Diminution of plasma membrane phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P2) levels through antibody sequestration or PLC-mediated hydrolysis mimics the potentiating effects of bradykinin or NGF at the cellular level. Moreover, recruitment of PLC-gamma to TrkA is essential for NGF-mediated potentiation of channel activity, and biochemical studies suggest that VR1 associates with this complex. These studies delineate a biochemical mechanism through which bradykinin and NGF produce hypersensitivity and might explain how the activation of PLC signalling systems regulates other members of the TRP channel family.     

Effectiveness of the global protected area network in representing species diversity

The Fifth World Parks Congress in Durban, South Africa, announced in September 2003 that the global network of protected areas now covers 11.5% of the planet's land surface. This surpasses the 10% target proposed a decade earlier, at the Caracas Congress, for 9 out of 14 major terrestrial biomes. Such uniform targets based on percentage of area have become deeply embedded into national and international conservation planning. Although politically expedient, the scientific basis and conservation value of these targets have been questioned. In practice, however, little is known of how to set appropriate targets, or of the extent to which the current global protected area network fulfils its goal of protecting biodiversity. Here, we combine five global data sets on the distribution of species and protected areas to provide the first global gap analysis assessing the effectiveness of protected areas in representing species diversity. We show that the global network is far from complete, and demonstrate the inadequacy of uniform--that is, 'one size fits all'--conservation targets.