Use of nonalpine anthropogenic habitats by American pikas ( Ochotona princeps ) in western Oregon

The American pika ( Ochotona princeps Richardson) has long been characterized in field guides and popular literature as an obligate inhabitant of alpine talus and as having relatively low dispersal capability. However, recent work reveals pikas to have broader habitat associations than previously reported. Over a large portion of the western slope of the Cascade Range in Oregon, pikas inhabit relatively low-elevation sites far from alpine areas and frequently occur in rocky man-made habitats such as roadcuts or rock quarries. We present observations of pikas in these previously overlooked habitats and discuss implications for (1) the proposed listing of the American pika as an endangered or threatened species; (2) furthering our understanding of pika population dynamics, habitat associations, and dispersal capabilites; and (3) management of federal, state, and private forest lands. Por mucho tiempo la pika americana ( Ochotona princeps Richardson) ha sido caracterizada en guías de campo y literatura popular como un habitante obligado de taludes alpinos y por tener una capacidad de dispersión relativamente baja. Sin embargo, trabajo reciente ha revelado que las pikas tienen asociaciones de hábitat más amplias de lo que hasta ahora se creía. En una gran parte de la vertiente occidental de la cordillera Cascade en Oregón, las pikas habitan sitios de elevación relativamente baja, lejos de las áreas alpinas y frecuentemente aparecen en hábitats rocosos artificiales tales como canteras y cortes de carretera. Presentamos observaciones de pikas en estos hábitats pasados por alto anteriormente y discutimos las implicaciones para (1) la propuesta de agregar la pika americana a la lista de especies amenazadas o en peligro; (2) ampliar nuestro conocimiento sobre la dinámica poblacional, las asociaciones de hábitat y la capacidad de dispersión; y (3) la gestión de tierras forestales federales, estatales y privadas.     

Taxonomic and nomenclatural rearrangements in Artemisia subgen. Tridentatae, including a redefinition of Sphaeromeria (Asteraceae, Anthemideae)

A recent molecular phylogenetic study of all members of Artemisia subgenus Tridentatae, as well as most of the other New World endemic Artemisia and the allied genera Sphaeromeria and Picrothamnus, raised the necessity of revising the taxonomic framework of the North American endemic Artemisia. Composition of the subgenus Tridentatae is enlarged to accommodate other North American endemics and is organized into 3 sections: Tridentatae, Nebulosae, and Filifoliae. This paper deals with the combination of one section, the amendment of 2 more sections, and the combination in or the reversion to Artemisia of some Sphaeromeria and Picrothamnus species. The new names given for previous Sphaeromeria species are Artemisia macarthurii (for S. argentea ), A. albicans (for S. cana ), A. constricta (for S. compacta ), and A. inaequifolia (for S. diversifolia ). The other Sphaeromeria we studied ( S. capitata, S. potentilloides, S. ruthiae, and S. simplex ) had been formerly considered Artemisia (respectively, A. capitata, A. potentilloides, A. ruthiae, and A. simplex ), and their previous nomenclature is therefore recommended. Un estudio reciente sobre la filogenia molecular de todos los miembros del subgénero Tridentatae de Artemisia, así como de la mayoría de las otras especies de Artemisia endémicas del Nuevo Mundo y los géneros afines Sphaeromeria y Picrothamnus, hizo ver la necesidad de revisar el marco taxonómico de las especies de Artemisia endémicas a Norteamérica. La composición del subgénero Tridentatae se ha ampliado para dar cabida a las otras especies endémicas de Norteamérica, y está organizado en 3 secciones: Tridentatae, Nebulosae y Filifoliae. El presente artículo trata sobre la combinación de una sección y la enmienda de 2 más, y propone la incorporación o reversión a Artemisia de algunas especies de Sphaeromeria y Picrothamnus. Los nuevos nombres de las especies previamente asignadas a Sphaeromeria son Artemisia macarthurii (para S. argentea ), A. albicans (para S. cana ), A. constricta (para S. compacta ) y A. inaequifolia (para S. diversifolia ). Las otras especies de Sphaeromeria estudiadas ( S. capitata, S. potentilloides, S. ruthiae y S. simplex ) habían sido previamente consideradas como miembros de Artemisia ( A. capitata, A. potentilloides, A. ruthiae y A. simplex, respectivamente), por lo quese recomienda utilizar su nomenclatura anterior.     

Dark induced increase in pineal serotonin N-acetyltransferase activity: A refractory period

Zusammenfassung Nachweis, dass Ratten, aus normaler Lichtperiode abrupt in Dunkelheit versetzt, keine Zunahme der NATase-Aktivität im Pinealorgan zeigen und dass Isoproterenol-Injektion die Zunahme der NATase auslöst.

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Support was provided to S. B. by NIH Postdoctoral Fellowship No. 1 FO2 HD 52858-01.

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We thankW. Langebartel andM. Veltrum.     

Structure of the Cul1-Rbx1-Skp1-F boxSkp2 SCF ubiquitin ligase complex

SCF complexes are the largest family of E3 ubiquitin-protein ligases and mediate the ubiquitination of diverse regulatory and signalling proteins. Here we present the crystal structure of the Cul1-Rbx1-Skp1-F boxSkp2 SCF complex, which shows that Cul1 is an elongated protein that consists of a long stalk and a globular domain. The globular domain binds the RING finger protein Rbx1 through an intermolecular beta-sheet, forming a two-subunit catalytic core that recruits the ubiquitin-conjugating enzyme. The long stalk, which consists of three repeats of a novel five-helix motif, binds the Skp1-F boxSkp2 protein substrate-recognition complex at its tip. Cul1 serves as a rigid scaffold that organizes the Skp1-F boxSkp2 and Rbx1 subunits, holding them over 100 A apart. The structure suggests that Cul1 may contribute to catalysis through the positioning of the substrate and the ubiquitin-conjugating enzyme, and this model is supported by Cul1 mutations designed to eliminate the rigidity of the scaffold.     

The stability of purified preparations of substance P

Zusammenfassung Hochgereinigte Präparate von Substanz P sind in verdünnter Lösung nicht stabil, da die aktive Substanz an Glas adsorbiert wird. Der Verlust an Wirksamkeit konnte durch Zusatz von Protein zur Lösung weitgehend verhindert werden. Die wirksame Substanz kontrahierte den Darm von Meerschweinchen, Huhn und Goldfisch, war aber am Rattenuterus fast wirkungslos.     

Quality assessment of the human genome sequence

As the final sequencing of the human genome has now been completed, we present the results of the largest examination of the quality of the finished DNA sequence. The completed study covers the major contributing sequencing centres and is based on a rigorous combination of laboratory experiments and computational analysis.     

G1 cell-cycle control and cancer

Before replicating DNA during their reproductive cycle, our cells enter a phase called G1 during which they interpret a flood of signals that influence cell division and cell fate. Mistakes in this process lead to cancer. An increasingly complex and coherent view of G1 signalling networks, which coordinate cell growth, proliferation, stress management and survival, is helping to define the roots of malignancies and shows promise for the development of better cancer therapies.     

Common effector processing mediates cell-specific responses to stimuli

The fundamental components of many signalling pathways are common to all cells. However, stimulating or perturbing the intracellular network often causes distinct phenotypes that are specific to a given cell type. This 'cell specificity' presents a challenge in understanding how intracellular networks regulate cell behaviour and an obstacle to developing drugs that treat signalling dysfunctions. Here we apply a systems-modelling approach to investigate how cell-specific signalling events are integrated through effector proteins to cause cell-specific outcomes. We focus on the synergy between tumour necrosis factor and an adenoviral vector as a therapeutically relevant stimulus that induces cell-specific responses. By constructing models that estimate how kinase-signalling events are processed into phenotypes through effector substrates, we find that accurate predictions of cell specificity are possible when different cell types share a common 'effector-processing' mechanism. Partial-least-squares regression models based on common effector processing accurately predict cell-specific apoptosis, chemokine release, gene induction, and drug sensitivity across divergent epithelial cell lines. We conclude that cell specificity originates from the differential activation of kinases and other upstream transducers, which together enable different cell types to use common effectors to generate diverse outcomes. The common processing of network signals by downstream effectors points towards an important cell biological principle, which can be applied to the understanding of cell-specific responses to targeted drug therapies.     

Plant composition and erosion potential of a grazed wetland in the salmon river subbasin, Idaho

Wetlands are dynamic habitats with many unique, important functions including filtering sediments and providing diverse habitats for fish and wildlife. Wetlands in the western United States are particularly important because they offer habitat for a number of protected runs of endangered fish species. Historically, livestock grazing has altered wetland and riparian area form and function by facilitating exotic species invasions, altering spatial heterogeneity of vegetation, and increasing erosion. In this study we examined vegetation structure and erosion potential in a wetland meadow exposed to unregulated grazing along Deer Creek in the Salmon River subbasin, Idaho. We characterized the vegetation composition and structure within the study area and attempted to assess potential erosion conditions using the Revised Universal Soil Loss Equation (RUSLE), an empirical approach developed by the U.S. Department of Agriculture—Agricultural Research Service (USDA-ARS). We found no significant spatial variability in species richness and noted a moderate number of exotic species in the total plant composition. Plant cover was higher near slightly entrenched banks, indicating that uncontrolled livestock were primarily occupying gently sloped streambanks and the interior of the meadow. Based on current vegetation composition and RUSLE results, uncontrolled grazing may be negatively impacting the study area. If uncontrolled grazing were excluded or carefully managed in the wetland meadows of the upper portion of the Deer Creek watershed, a reduction in excess sediments to Deer Creek may occur.     

CpG island methylator phenotype underlies sporadic microsatellite instability and is tightly associated with BRAF mutation in colorectal cancer

Aberrant DNA methylation of CpG islands has been widely observed in human colorectal tumors and is associated with gene silencing when it occurs in promoter areas. A subset of colorectal tumors has an exceptionally high frequency of methylation of some CpG islands, leading to the suggestion of a distinct trait referred to as 'CpG island methylator phenotype', or 'CIMP'. However, the existence of CIMP has been challenged. To resolve this continuing controversy, we conducted a systematic, stepwise screen of 195 CpG island methylation markers using MethyLight technology, involving 295 primary human colorectal tumors and 16,785 separate quantitative analyses. We found that CIMP-positive (CIMP+) tumors convincingly represent a distinct subset, encompassing almost all cases of tumors with BRAF mutation (odds ratio = 203). Sporadic cases of mismatch repair deficiency occur almost exclusively as a consequence of CIMP-associated methylation of MLH1 . We propose a robust new marker panel to classify CIMP+ tumors.