Influence of an abscisic acid (ABA) seed coating on seed germination rate and timing of Bluebunch Wheatgrass.

Semi-arid rangeland degradation is a reoccurring issue throughout the world. In the Great Basin of North America, seeds sown in the fall to restore degraded sagebrush ( spp.) steppe plant communities may experience high mortality in winter due to exposure of seedlings to freezing temperatures and other stressors.

Invertebrate community response to fire and rodent activity in the Mojave and Great Basin Deserts.

Recent increases in the frequency and size of desert wildfires bring into question the impacts of fire on desert invertebrate communities. Furthermore, consumer communities can strongly impact invertebrates through predation and top-down effects on plant community assembly. We experimentally applied burn and rodent exclusion treatments in a full factorial design at sites in both the Mojave and Great Basin deserts to examine the impact that fire and rodent consumers have on invertebrate communities.

Postdispersal Infection and Disease Development of Pyrenophora semeniperda in Bromus tectorum Seeds.

The Ascomycete fungus, Pyrenophora semeniperda, attacks a broad range of cool-season grasses. While leaf and predispersal infection of seeds (i.e.

Increased Primary Production from an Exotic Invader Does Not Subsidize Native Rodents.

Invasive plants have tremendous potential to enrich native food webs by subsidizing net primary productivity. Here, we explored how a potential food subsidy, seeds produced by the aggressive invader cheatgrass (Bromus tectorum), is utilized by an important guild of native consumers--granivorous small mammals--in the Great Basin Desert, USA. In a series of field experiments we examined 1) how cheatgrass invasion affects the density and biomass of seed rain at the ecosystem-level; 2) how seed resources from cheatgrass numerically affect granivorous small mammals; and 3) how the food preferences of native granivores might mediate the trophic integration of cheatgrass seeds.

Hydrothermal time models for conidial germination and mycelial growth of the seed pathogen Pyrenophora semeniperda.

Population-based threshold models using hydrothermal time (HTT) have been widely used to model seed germination. We used HTT to model conidial germination and mycelial growth for the seed pathogen Pyrenophora semeniperda in a novel approach to understanding its interactions with host seeds. Germination time courses and mycelial growth rates for P.

Indirect effects of an invasive annual grass on seed fates of two native perennial grass species.

Invasive plants exhibit both direct and indirect negative effects on recruitment of natives following invasion. We examined indirect effects of the invader Bromus tectorum (cheatgrass) on seed fates of two native grass species, Elymus elymoides and Pseudoroegneria spicata, by removing B. tectorum and by adding inoculum of the shared seed pathogen Pyrenophora semeniperda in factorial experiments at xeric and mesic field sites.

Strategic aspects of young, healthy older adults', and Alzheimer patients' arithmetic performance.

Forty young adults, 40 healthy older adults, and 23 probable AD patients were asked to solve simple subtraction problems (e.g., 9-3; 14-9) in a choice condition and in a no-choice condition.

Biological effects of short-term or prolonged administration of 9-[2-(phosphonomethoxy)propyl]adenine (tenofovir) to newborn and infant rhesus macaques.

The reverse transcriptase inhibitor 9-[2-(phosphonomethoxy)propyl]adenine (PMPA; tenofovir) was previously found to offer strong prophylactic and therapeutic benefits in an infant macaque model of pediatric human immunodeficiency virus (HIV) infection. We now summarize the toxicity and safety of PMPA in these studies. When a range of PMPA doses (4 to 30 mg/kg of body weight administered subcutaneously once daily) was administered to 39 infant macaques for a short period of time (range, 1 day to 12 weeks), no adverse effects on their health or growth were observed; this included a subset of 12 animals which were monitored for more than 2 years.

Ecological genetics of seed germination regulation in Bromus tectorum L. : II. Reaction norms in response to a water stress gradient imposed during seed maturation.

The probability that a seed will germinate depends on factors associated with genotype, maturation environment, post-maturation history, and germination environment. In this study, we examined the interaction among these sets of factors for 18 inbred lines from six populations of Bromus tectorum L., a winter annual grass that is an important weed in the semi-arid western United States.

Ecological genetics of seed germination regulation in Bromus tectorum L. : I. Phenotypic variance among and within populations.

Regulation of seed germination phenology is an important aspect of the life history strategy of invading annual plant species. In the obligately selfing winter annual grass Bromus tectorum, seeds are at least conditionally dormant at dispersal in early summer and lose dormancy through dry-afterripening. Patterns of germination response at dispersal vary among populations and sometimes across years within populations.