Distinct amino acid compositional requirements for formation and maintenance of the [PSI+] prion in yeast

Multiple yeast prions have been identified that result from the structural conversion of proteins into a self-propagating amyloid form. Amyloid-based prion activity in yeast requires a series of discrete steps. First, the prion protein must form an amyloid nucleus that can recruit and structurally convert additional soluble proteins. Subsequently, maintenance of the prion during cell division requires fragmentation of these aggregates to create new heritable propagons. For the Saccharomyces cerevisiae prion protein Sup35, these different activities are encoded by different regions of the Sup35 prion domain. An N-terminal glutamine/asparagine-rich nucleation domain is required for nucleation and fiber growth, while an adjacent oligopeptide repeat domain is largely dispensable for prion nucleation and fiber growth but is required for chaperone-dependent prion maintenance. Although prion activity of glutamine/asparagine-rich proteins is predominantly determined by amino acid composition, the nucleation and oligopeptide repeat domains of Sup35 have distinct compositional requirements. Here, we quantitatively define these compositional requirements in vivo. We show that aromatic residues strongly promote both prion formation and chaperone-dependent prion maintenance. In contrast, nonaromatic hydrophobic residues strongly promote prion formation but inhibit prion propagation. These results provide insight into why some aggregation-prone proteins are unable to propagate as prions

Ocorrencia e abundância de espécies de plantas ameaçadas de extinção no entorno do reservatório da UHE Barra Grande.

Modelos de ocorrência e abundância de espécies são ferramentas atuais que devem ser incorporadas na conservação da biodiversidade no entorno de reservatórios de usinas hidroelétricas, prevendo ou planejando ações necessárias para mitigar os impactos ambientais destes empreendimentos. Neste estudo, nossos objetivos foram: modelar a ocorrência e abundância de espécies de plantas ameaçadas de extinção, verificar a relação entre a ocorrência prevista e a abundância observada e avaliar se os modelos baseados em abundância são mais eficientes em predizer a ocorrência do que aqueles baseados em dados de ocorrência (0/1). Representantes individuais de nove espécies (Araucaria angustifolia (Bertol.) Kuntze (Araucariaceae), Butia eriospatha (Mart. ex Drude) Becc. (Arecaceae), Clethra scabra Pers. (Clethraceae), Dicksonia sellowiana (Presl.) Hook. (Dicksoniaceae), Erythrina falcata Benth. (Fabaceae), Maytenus ilicifolia (Schrad.) Planch. (Celastraceae), Myrocarpus frondosus Allemão (Fabaceae), Podocarpus lambertii Klotzsch ex Endl. (Podocarpaceae) e Trithrinax brasiliensis Mart (Arecaceae)) foram contados em 388 parcelas (10x50m) aleatoriamente alocadas e georreferenciadas no entorno do reservatório da UHE Barra Grande (SC/RS). Modelamos sua relação com 15 variáveis ambientais utilizando dados de ocorrência (GLM) e abundância (Modelos Hurdle e Zero-inflado). Em geral, os modelos de ocorrência foram mais precisos do que os modelos de abundância. Para todas as espécies, a abundância observada foi correlacionada com a probabilidade de ocorrência, sugerindo que estudos futuros poderiam utilizar esta informação, em vez da abundância. Reconstruir padrões de abundância e de ocorrência é uma importante ferramenta para o planejamento de ações de conservação e manejo de espécies ameaçadas, permitindo que sejam indicadas as melhores áreas para a coleta e reintrodução de germoplasma vegetal ou mesmo a escolha de áreas de conservação com maior probabilidade de manter populações viáveis

youth Digital Skills Indicator:German questionnaire

The youth Digital Skills Indicator was developed as part of the ‘Youth Skills (ySKILLS)’ project and added to the ‘From Digital Skills to Tangible Outcomes’ digital skills measurement toolkit.Please read the accompanying document on the underlying rationale for these scales and on how to create and use composite scales in the following document: Helsper, E.J., Schneider, L., van Deursen, A.J.A.M., van Laar, E. (2021). The youth Digital Skills Indicator: Report on the conceptualisation and development of the ySKILLS digital skills measure. KU Leuven, Leuven: ySKILLS. Available at: https://yskills.eu

Further functional determinants

Functional determinants for the scalar Laplacian on spherical caps and slices, flat balls, shells and generalised cylinders are evaluated in two, three and four dimensions using conformal techniques. Both Dirichlet and Robin boundary conditions are allowed for. Some effects of non-smooth boundaries are discussed; in particular the 3-hemiball and the 3-hemishell are considered. The edge and vertex contributions to the $C_{3/2}$ coefficient are examined.Comment: 25 p,JyTex,5 figs. on request

Single-Pion Production in pp Collisions at 0.95 GeV/c (II)

The single-pion production reactions $pp\to d\pi^+$, $pp\to np\pi^+$ and $pp\to pp\pi^0$ were measured at a beam momentum of 0.95 GeV/c ($T_p \approx$ 400 MeV) using the short version of the COSY-TOF spectrometer. The central calorimeter provided particle identification, energy determination and neutron detection in addition to time-of-flight and angle measurements from other detector parts. Thus all pion production channels were recorded with 1-4 overconstraints. Main emphasis is put on the presentation and discussion of the $np\pi^+$ channel, since the results on the other channels have already been published previously. The total and differential cross sections obtained are compared to theoretical calculations. In contrast to the $pp\pi^0$ channel we find in the $np\pi^+$ channel a strong influence of the $\Delta$ excitation already at this energy close to threshold. In particular we find a $(3 cos^2\Theta + 1)$ dependence in the pion angular distribution, typical for a pure s-channel $\Delta$ excitation and identical to that observed in the $d\pi^+$ channel. Since the latter is understood by a s-channel resonance in the $^1D_2$ $pn$ partial wave, we discuss an analogous scenario for the $pn\pi^+$ channel

Markov Properties of Electrical Discharge Current Fluctuations in Plasma

Using the Markovian method, we study the stochastic nature of electrical discharge current fluctuations in the Helium plasma. Sinusoidal trends are extracted from the data set by the Fourier-Detrended Fluctuation analysis and consequently cleaned data is retrieved. We determine the Markov time scale of the detrended data set by using likelihood analysis. We also estimate the Kramers-Moyal's coefficients of the discharge current fluctuations and derive the corresponding Fokker-Planck equation. In addition, the obtained Langevin equation enables us to reconstruct discharge time series with similar statistical properties compared with the observed in the experiment. We also provide an exact decomposition of temporal correlation function by using Kramers-Moyal's coefficients. We show that for the stationary time series, the two point temporal correlation function has an exponential decaying behavior with a characteristic correlation time scale. Our results confirm that, there is no definite relation between correlation and Markov time scales. However both of them behave as monotonic increasing function of discharge current intensity. Finally to complete our analysis, the multifractal behavior of reconstructed time series using its Keramers-Moyal's coefficients and original data set are investigated. Extended self similarity analysis demonstrates that fluctuations in our experimental setup deviates from Kolmogorov (K41) theory for fully developed turbulence regime.Comment: 25 pages, 9 figures and 4 tables. V3: Added comments, references, figures and major correction

The laurentian record of neoproterozoic glaciation, tectonism, and eukaryotic evolution in Death Vally, California

Neoproterozoic strata in Death Valley, California contain eukaryotic microfossils and glacial deposits that have been used to assess the severity of putative Snowball Earth events and the biological response to extreme environmental change. These successions also contain evidence for syn-sedimentary faulting that has been related to the rifting of Rodinia, and in turn the tectonic context of the onset of Snowball Earth. These interpretations hinge on local geological relationships and both regional and global stratigraphic correlations. Here we present new geological mapping, measured stratigraphic sections, carbon and strontium isotope chemostratigraphy, and micropaleontology from the Neoproterozoic glacial deposits and bounding strata in Death Valley. These new data enable us to refine regional correlations both across Death Valley and throughout Laurentia, and construct a new age model for glaciogenic strata and microfossil assemblages. Particularly, our remapping of the Kingston Peak Formation in the Saddle Peak Hills and near the type locality shows for the first time that glacial deposits of both the Marinoan and Sturtian glaciations can be distinguished in southeastern Death Valley, and that beds containing vase-shaped microfossils are slump blocks derived from the underlying strata. These slump blocks are associated with multiple overlapping unconformities that developed during syn-sedimentary faulting, which is a common feature of Cyrogenian strata along the margin of Laurentia from California to Alaska. With these data, we conclude that all of the microfossils that have been described to date in Neoproterozoic strata of Death Valley predate the glaciations and do not bear on the severity, extent or duration of Neoproterozoic Snowball Earth events