Phylogeny and Biogeography of Endemic Festuca (Poaceae) from New Zealand Based on Nuclear (ITS) and Chloroplast (trnL–trnF) Nucleotide Sequences

We investigated the phylogenetic relationships of the endemic New Zealand (NZ) species of Festuca (Poaceae, Pooideae) by assessing sequence variation from the nuclear internal transcribed spacers (ITS) and a chloroplast intergenic spacer (trnL–trnF) and by measuring DNA content using flow cytometry. The ITS and trnL–trnF data sets were congruent in showing that the NZ species of Festuca have two origins. One group, containing F. coxii, F. luciarum, F. multinodis, and F. ultramafica, is closely related to Festuca sect. Aulaxyper. The other group includes a clade of five endemic species (F. actae, F. deflexa, F. madida, F. matthewsii, F. novae-zelandiae) and one species (F. contracta) with a circum-Antarctic distribution. The North American species F. californica is sister to the latter group in the trnL–trnF phylogeny but not so in the ITS phylogeny. The differentiation of endemic NZ species into two groups is supported by differences in chromosome number and genome size, the latter showing an inverse relationship to ploidy level. We discuss the ecology and biogeography of NZ’s endemic species of Festuca. Origin from Northern Hemisphere ancestors via dispersal to NZ through the American continents is a plausible hypothesis based on current information

Gravitational Potential Reconstruction from Peculiar Velocity and Weak Lensing Measurements

We present an analytic method for rapidly forecasting the accuracy of gravitational potential reconstruction possible from measurement of radial peculiar velocities of every galaxy cluster with M > M_th in solid angle \theta^2 and over redshift range z_min < z < z_max. These radial velocities can be determined from measurement of the kinetic and thermal Sunyaev-Zeldovich effects. For a shallow survey with 0.2 < z < 0.4, coincident with the SDSS photometric survey, one mode of the gravitational potential (on length scales > 60 Mpc) can be reconstructed for every ~8 cluster velocity determinations. Deeper surveys require measurement of more clusters per S/N > 1 mode. Accuracy is limited by the ``undersampling noise'' due to our non-observation of the large fraction of mass that is not in galaxy clusters. Determining the gravitational potential will allow for detailed study of the relationship between galaxies and their surrounding large-scale density fields over a wide range of redshifts, and test the gravitational instability paradigm on very large scales. Observation of weak lensing by large-scale structure provides complementary information since lensing is sensitive to the tangential modes that do not affect the velocity.Comment: 4 pages, 3 figures, submitted to ApJ Letter

New Arabidopsis recombinant inbred lines (Landsberg erecta x Nossen) reveal natural variation in phytochrome-mediated responses

We used 52 Arabidopsis (Arabidopsis thaliana) accessions and developed a new set of 137 recombinant inbred lines between Landsberg erecta (Ler) and Nossen (No-0) to explore the genetic basis of phytochrome-mediated responses during deetiolation. Unexpectedly, most accessions showed weak or moderate hypocotyl growth and cotyledon unfolding responses to pulses of far-red light (FR). Crosses between Columbia and No-0, two accessions with poor response, segregated seedlings with unfolded cotyledons under pulsed FR, suggesting the occurrence of accession-specific loci in the repression of morphological responses to weak light signals. Confirming the latter expectation, mapping of responses to pulsed FR in the Ler x No-0 lines identified novel loci. Despite its weak response to pulsed FR, No-0 showed a response to continuous FR stronger than that observed in Ler. By mapping the differential effect of pulsed versus continuous FR, we identified two high-irradiance response loci that account for the steeper response to continuous FR in No-0. This underscores the potential of the methodology to identify loci involved in the regulation of the shape of signal input-output relationships. Loci specific for a given phytochrome-mediated response were more frequent than pleiotropic loci. Segregation of these specific loci is predicted to yield different combinations of seedling responsivity to light. Such flexibility in combination of responses is observed among accessions and could aid in the adjustment to different microenvironments.Instituto de Investigaciones Bioquímicas de La Plat

Light scattering corrections to linear dichroism spectroscopy for liposomes in shear flow using calcein fluorescence and modified Rayleigh-Gans-Debye-Mie scattering

The interpretation of data from absorbance spectroscopy experiments of liposomes in flow systems is often complicated by the fact that there is currently no easy way to account for scattering artefacts. This has proved particularly problematic for linear dichroism (LD) spectroscopy, which may be used to determine binding modes of small molecules, peptides and proteins to liposomes if we can extract the absorbance signal from the combined absorbance/scattering experiment. Equations for a modified Rayleigh-Gans-Debye (RGD) approximation to the turbidity (scattering) LD spectrum are available in the literature though have not been implemented. This review summarises the literature and shows how it can be implemented. The implementation proceeds by first determining volume loss that occurs when a spherical liposome is subjected to flow. Calcein fluorescence can be used for this purpose since at high concentrations (> 60 mM) it has low intensity fluorescence with maxima at 525 and 563 nm whereas at low concentrations (<1 mM) the fluorescence intensity is enhanced and the band shifts to 536 nm. The scattering calculation process yields the average axis ratios of the distorted liposome ellipsoids and extent of orientation of the liposomes in flow. The scattering calculations require methods to estimate liposome integrity, volume loss, and orientation when subjected to shear stresses under flow

The PHASES Differential Astrometry Data Archive. V. Candidate Substellar Companions to Binary Systems

The Palomar High-precision Astrometric Search for Exoplanet Systems monitored 51 subarcsecond binary systems to evaluate whether tertiary companions as small as Jovian planets orbited either the primary or secondary stars, perturbing their otherwise smooth Keplerian motions. Six binaries are presented that show evidence of substellar companions orbiting either the primary or secondary star. Of these six systems, the likelihoods of two of the detected perturbations to represent real objects are considered to be "high confidence", while the remaining four systems are less certain and will require continued observations for confirmation.Comment: 16 Pages, Accepted to A

prepared for

We thank the U.S. Environmental Protection Agency (Office of Water; Nationa

Evaluation of Germline BMP4 Mutation as a Cause of Colorectal Cancer

Transforming growth factor-â (TGF-â) signalling plays a key role in colorectal cancer (CRC). Bone morphogenetic protein-4 (BMP4) is a member of the TGF-â family of signal transduction molecules. To examine if germline mutation in BMP4 causes CRC we analysed 504 genetically enriched CRC cases (by virtue of early-onset disease, family history of CRC) for mutations in the coding sequence of BMP4. We identified three pathogenic mutations, p.R286X (g.8330C>T), p.W325C (g.8449G>T) and p.C373S (g.8592G>C), amongst the CRC cases which were not observed in 524 healthy controls. p.R286X localizes to the N-terminal of the TGF-â1 prodomain truncating the protein prior to the active domain. p.W325C and p.C373S mutations are predicted from protein homology modelling with BMP2 to impact deleteriously on BMP4 function. Segregation of p.C373S with adenoma and hyperplastic polyp in first-degree relatives of the case suggests germline mutations may confer a juvenile polyposis-type phenotype. These findings suggest mutation of BMP4is a cause of CRC and the value of protein-based modelling in the elucidation of rare disease-causing variants. © 2010 Wiley-Liss, Inc

Evidence and Ideology in Macroeconomics: The Case of Investment Cycles

The paper reports the principal findings of a long term research project on the description and explanation of business cycles. The research strongly confirmed the older view that business cycles have large systematic components that take the form of investment cycles. These quasi-periodic movements can be represented as low order, stochastic, dynamic processes with complex eigenvalues. Specifically, there is a fixed investment cycle of about 8 years and an inventory cycle of about 4 years. Maximum entropy spectral analysis was employed for the description of the cycles and continuous time econometrics for the explanatory models. The central explanatory mechanism is the second order accelerator, which incorporates adjustment costs both in relation to the capital stock and the rate of investment. By means of parametric resonance it was possible to show, both theoretically and empirically how cycles aggregate from the micro to the macro level. The same mathematical tool was also used to explain the international convergence of cycles. I argue that the theory of investment cycles was abandoned for ideological, not for evidential reasons. Methodological issues are also discussed