RESUMO
In western North American conifer forests, wildfires are increasing in frequency and severity due to heavy fuel loads that have accumulated after a century of fire suppression. Forest restoration treatments (e.g., thinning and/or burning) are being designed and implemented at large spatial and temporal scales in an effort to reduce fire risk and restore forest structure and function. In ponderosa pine (Pinus ponderosa) forests, predominantly open forest structure and a frequent, low-severity fire regime constituted the evolutionary environment for wildlife that persisted for thousands of years. Small mammals are important in forest ecosystems as prey and in affecting primary production and decomposition. During 2006-2009, we trapped eight species of small mammals at 294 sites in northern Arizona and used occupancy modeling to determine community responses to thinning and habitat features. The most important covariates in predicting small mammal occupancy were understory vegetation cover, large snags, and treatment. Our analysis identified two generalist species found at relatively high occupancy rates across all sites, four open-forest species that responded positively to treatment, and two dense-forest species that responded negatively to treatment unless specific habitat features were retained. Our results indicate that all eight small mammal species can benefit from restoration treatments, particularly if aspects of their evolutionary environment (e.g., large trees, snags, woody debris) are restored. The occupancy modeling approach we used resulted in precise species-level estimates of occupancy in response to habitat attributes for a greater number of small mammal species than in other comparable studies. We recommend our approach for other studies faced with high variability and broad spatial and temporal scales in assessing impacts of treatments or habitat alteration on wildlife species. Moreover, since forest planning efforts are increasingly focusing on progressively larger treatment implementation, better and more efficiently obtained ecological information is needed to inform these efforts.
Assuntos
Conservação dos Recursos Naturais/métodos , Ecossistema , Muridae/fisiologia , Pinus ponderosa/fisiologia , Sciuridae/fisiologia , Árvores , Animais , Arizona , Monitoramento AmbientalRESUMO
A series of N6,2-disubstituted adenosine analogues have been synthesized and their functional activity measured against A2a and A1 receptors. Examples of compounds with both a lipophilic N6-substituent and amino-functionalized 2-position were highly active at the A2a receptor on the human neutrophil.
Assuntos
Adenosina/química , Adenosina/farmacologia , Agonistas do Receptor Purinérgico P1 , Adenosina/análogos & derivados , Anti-Inflamatórios/química , Proteínas de Ligação ao GTP , Solubilidade , Relação Estrutura-AtividadeRESUMO
The synthesis and in vitro evaluation of the acetamidine derivatives of hetero-substituted lysine and homolysine analogues have identified potent inhibitors of human nitric oxide synthase enzymes, including examples with marked selectivity for the inducible isoform.
Assuntos
Acetamidas/síntese química , Inibidores Enzimáticos/síntese química , Lisina/análogos & derivados , Lisina/síntese química , Óxido Nítrico Sintase/antagonistas & inibidores , Acetamidas/farmacologia , Inibidores Enzimáticos/farmacologia , Humanos , Indicadores e Reagentes , Isoenzimas/antagonistas & inibidores , Lisina/farmacologia , Óxido Nítrico Sintase Tipo II , Ornitina/análogos & derivados , Ornitina/farmacologia , Sulfetos/farmacologia , Sulfonas/farmacologiaRESUMO
Systematic modification of the presumed P1 side chain in a series of (carboxyalkyl)amino-based inhibitors of matrix metalloproteinases enabled identification of the 2-(1,3-dihydro-1,3-dioxo-2H-benz[f]isoindol-2-yl)ethyl group as a preferred substituent imparting potent inhibition of the enzymes collagenase and gelatinase. It was subsequently found that the P2'-P3' residues in this series could be replaced by small non-peptide residues, while maintaining inhibitory potency. The imide group in this series of compounds can undergo autocatalytic hydrolysis under neutral conditions.
Assuntos
Dipeptídeos/química , Matriz Extracelular/enzimologia , Indóis/química , Metaloendopeptidases/antagonistas & inibidores , Zinco , Sequência de Aminoácidos , Compostos Cromogênicos/metabolismo , Dipeptídeos/síntese química , Dipeptídeos/farmacologia , Estabilidade de Medicamentos , Corantes Fluorescentes , Gelatinases/antagonistas & inibidores , Meia-Vida , Humanos , Concentração de Íons de Hidrogênio , Indóis/síntese química , Indóis/farmacologia , Isoindóis , Metaloproteinase 3 da Matriz , Inibidores de Metaloproteinases de Matriz , Dados de Sequência Molecular , Estrutura Molecular , Relação Estrutura-AtividadeRESUMO
A locus is described that controls levels of mitochondrial dihydroorotate dehydrogenase (EC 1.3.3.1) in Drosophila melanogaster. The effects of alleles of the locus, Dhod, are manifest in preparations from whole organisms as well as in partially purified mitochondrial preparations; however, other mitochondrial functions do not appear to be appreciably affected by Dhod genotypes. The locus maps near p in the proximal portion of the right arm of chromosome 3. Flies trisomic for a chromosome segment including that region display elevated enzyme levels, implying that an enzyme structural gene is in that vicinity. Furthermore, Dhod alleles are semidominant in heterozygotes, suggesting that the dosage-sensitive element detected in the trisomics is actually the Dhod locus. These findings are discussed relative to the role of dihydroorotate dehydrogenase in the de novo pyrimidine biosynthetic pathway and relative to other pathway mutants that have been described in Drosophila.