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1.
Proc Natl Acad Sci U S A ; 111(30): 11002-6, 2014 Jul 29.
Artículo en Inglés | MEDLINE | ID: mdl-25002496

RESUMEN

Vernal pools are far more important for providing ecosystem services than one would predict based on their small size. However, prevailing resource-management strategies are not effectively conserving pools and other small natural features on private lands. Solutions are complicated by tensions between private property and societal rights, uncertainties over resource location and function, diverse stakeholders, and fragmented regulatory authority. The development and testing of new conservation approaches that link scientific knowledge, stakeholder decision-making, and conservation outcomes are important responses to this conservation dilemma. Drawing from a 15-y history of vernal pool conservation efforts in Maine, we describe the coevolution of pool conservation and research approaches, focusing on how research-based knowledge was produced and used in support of management decisions. As management shifted from reactive, top-down approaches to proactive and flexible approaches, research shifted from an ecology-focused program to an interdisciplinary program based on social-ecological systems. The most effective strategies for linking scientific knowledge with action changed as the decision-makers, knowledge needs, and context for vernal pool management advanced. Interactions among stakeholders increased the extent to which knowledge was coproduced and shifted the objective of stakeholder engagement from outreach to research collaboration and development of innovative conservation approaches. New conservation strategies were possible because of the flexible, solutions-oriented collaborations and trust between scientists and decision-makers (fostered over 15 y) and interdisciplinary, engaged research. Solutions to the dilemma of conserving small natural features on private lands, and analogous sustainability science challenges, will benefit from repeated negotiations of the science-policy boundary.


Asunto(s)
Conservación de los Recursos Naturales , Toma de Decisiones en la Organización , Ecosistema , Animales , Humanos , Maine
3.
Biochem Biophys Res Commun ; 470(2): 473-478, 2016 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-26718405

RESUMEN

BACKGROUND: Basolateral K(+) channels hyperpolarize colonocytes to ensure Na(+) (and thus water) absorption. Small conductance basolateral (KCNQ1/KCNE3) K(+) channels have never been evaluated in human colon. We therefore evaluated KCNQ1/KCNE3 channels in distal colonic crypts obtained from normal and active ulcerative colitis (UC) patients. METHODS: KCNQ1 and KCNE3 mRNA levels were determined by qPCR, and KCNQ1/KCNE3 channel activity in normal and UC crypts, and the effects of forskolin (activator of adenylate cyclase) and UC-related proinflammatory cytokines on normal crypts, studied by patch clamp recording. RESULTS: Whereas KCNQ1 and KCNE3 mRNA expression was similar in normal and UC crypts, single 6.8 pS channels were seen in 36% of basolateral patches in normal crypts, and to an even greater extent (74% of patches, P < 0.001) in UC crypts, with two or more channels per patch. Channel activity was 10-fold higher (P < 0.001) in UC crypts, with a greater contribution to basolateral conductance (5.85 ± 0.62 mS cm(-2)) than in controls (0.28 ± 0.04 mS cm(-2), P < 0.001). In control crypts, forskolin and thromboxane A2 stimulated channel activity 30-fold and 10-fold respectively, while PGE2, IL-1ß, and LTD4 had no effect. CONCLUSIONS: KCNQ1/KCNE3 channels make only a small contribution to basolateral conductance in normal colonic crypts, with increased channel activity in UC appearing insufficient to prevent colonic cell depolarization in this disease. This supports the proposal that defective Na(+) absorption rather than enhanced Cl(-) secretion, is the dominant pathophysiological mechanism of diarrhea in UC.


Asunto(s)
Membrana Celular/metabolismo , Colitis Ulcerosa/metabolismo , Canal de Potasio KCNQ1/metabolismo , Potenciales de la Membrana , Canales de Potasio con Entrada de Voltaje/metabolismo , Potasio/metabolismo , Células Cultivadas , Colon/metabolismo , Humanos , Mucosa Intestinal/metabolismo , Activación del Canal Iónico , Regulación hacia Arriba
4.
Conserv Biol ; 29(3): 630-9, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-25923307

RESUMEN

Geodiversity--the variability of Earth's surface materials, forms, and physical processes-is an integral part of nature and crucial for sustaining ecosystems and their services. It provides the substrates, landform mosaics, and dynamic physical processes for habitat development and maintenance. By determining the heterogeneity of the physical environment in conjunction with climate interactions, geodiversity has a crucial influence on biodiversity across a wide range of scales. From a literature review, we identified the diverse values of geodiversity; examined examples of the dependencies of biodiversity on geodiversity at a site-specific scale (for geosites <1 km(2) in area); and evaluated various human-induced threats to geosites and geodiversity. We found that geosites are important to biodiversity because they often support rare or unique biota adapted to distinctive environmental conditions or create a diversity of microenvironments that enhance species richness. Conservation of geodiversity in the face of a range of threats is critical both for effective management of nature's stage and for its own particular values. This requires approaches to nature conservation that integrate climate, biodiversity, and geodiversity at all spatial scales.


Asunto(s)
Biodiversidad , Conservación de los Recursos Naturales , Fenómenos Geológicos , Clima , Ecosistema
5.
Conserv Biol ; 29(3): 640-8, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-25924205

RESUMEN

Climate change will require novel conservation strategies. One such tactic is a coarse-filter approach that focuses on conserving nature's stage (CNS) rather than the actors (individual species). However, there is a temporal mismatch between the long-term goals of conservation and the short-term nature of most ecological studies, which leaves many assumptions untested. Paleoecology provides a valuable perspective on coarse-filter strategies by marshaling the natural experiments of the past to contextualize extinction risk due to the emerging impacts of climate change and anthropogenic threats. We reviewed examples from the paleoecological record that highlight the strengths, opportunities, and caveats of a CNS approach. We focused on the near-time geological past of the Quaternary, during which species were subjected to widespread changes in climate and concomitant changes in the physical environment in general. Species experienced a range of individualistic responses to these changes, including community turnover and novel associations, extinction and speciation, range shifts, changes in local richness and evenness, and both equilibrium and disequilibrium responses. Due to the dynamic nature of species responses to Quaternary climate change, a coarse-filter strategy may be appropriate for many taxa because it can accommodate dynamic processes. However, conservationists should also consider that the persistence of landforms varies across space and time, which could have potential long-term consequences for geodiversity and thus biodiversity.


Asunto(s)
Biodiversidad , Cambio Climático , Conservación de los Recursos Naturales , Fenómenos Geológicos
6.
Conserv Biol ; 29(3): 692-701, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-25923052

RESUMEN

In a rapidly changing climate, conservation practitioners could better use geodiversity in a broad range of conservation decisions. We explored selected avenues through which this integration might improve decision making and organized them within the adaptive management cycle of assessment, planning, implementation, and monitoring. Geodiversity is seldom referenced in predominant environmental law and policy. With most natural resource agencies mandated to conserve certain categories of species, agency personnel are challenged to find ways to practically implement new directives aimed at coping with climate change while retaining their species-centered mandate. Ecoregions and ecological classifications provide clear mechanisms to consider geodiversity in plans or decisions, the inclusion of which will help foster the resilience of conservation to climate change. Methods for biodiversity assessment, such as gap analysis, climate change vulnerability analysis, and ecological process modeling, can readily accommodate inclusion of a geophysical component. We adapted others' approaches for characterizing landscapes along a continuum of climate change vulnerability for the biota they support from resistant, to resilient, to susceptible, and to sensitive and then summarized options for integrating geodiversity into planning in each landscape type. In landscapes that are relatively resistant to climate change, options exist to fully represent geodiversity while ensuring that dynamic ecological processes can change over time. In more susceptible landscapes, strategies aiming to maintain or restore ecosystem resilience and connectivity are paramount. Implementing actions on the ground requires understanding of geophysical constraints on species and an increasingly nimble approach to establishing management and restoration goals. Because decisions that are implemented today will be revisited and amended into the future, increasingly sophisticated forms of monitoring and adaptation will be required to ensure that conservation efforts fully consider the value of geodiversity for supporting biodiversity in the face of a changing climate.


Asunto(s)
Biodiversidad , Conservación de los Recursos Naturales/métodos , Toma de Decisiones , Política Ambiental/legislación & jurisprudencia , Fenómenos Geológicos , Cambio Climático , Conservación de los Recursos Naturales/legislación & jurisprudencia
7.
Gut ; 63(3): 472-9, 2014 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-23740188

RESUMEN

BACKGROUND: Human colon may secrete substantial amounts of water secondary to chloride (Cl(-)) and/or potassium (K(+)) secretion in a variety of diarrhoeal diseases. Ion secretion occurs via Cl(-) and K(+) channels, which are generally assumed to be co-located in the colonocyte apical membrane, although their exact cellular sites remain unclear. OBJECTIVE:  To investigate the location of apical Cl(-) (CFTR) and apical K(+) (large conductance; BK) channels within human colonic epithelium. DESIGN: Whole-cell patch clamp recordings were obtained from intact human colonic crypts. Specific blockers of K(+) channels and CFTR identified different types of K(+) channel and CFTR under resting conditions and after stimulating intracellular cAMP with forskolin. The BK channel ß3-subunit was localised by immunostaining. RESULTS: Two types of crypt cells were identified. One (73% of cells) had whole-cell currents dominated by intermediate conductance (IK) K(+) channels under resting conditions, which developed large CFTR-mediated currents in response to increasing intracellular cAMP. The other (27% of cells) had resting currents dominated by BK channels inhibited by the BK channel blocker penitrem A, but insensitive to both forskolin and the IK channel blocker clotrimazole. Immunostaining showed co-localisation of the BK channel ß3-subunit and the goblet cell marker, MUC2. CONCLUSIONS: In human colon, Cl(-) secretion originates from the dominant population of colonocytes expressing apical CFTR, whereas K(+) secretion is derived from a smaller population of goblet cells expressing apical BK channels. These findings provide new insights into the pathophysiology of secretory diarrhoea and should be taken into account during the development of anti-diarrhoeal drugs.


Asunto(s)
Canales de Cloruro/metabolismo , Cloruros/metabolismo , Colon/metabolismo , Mucosa Intestinal/metabolismo , Canales de Potasio de Gran Conductancia Activados por el Calcio/metabolismo , Potasio/metabolismo , Biomarcadores/metabolismo , Colon/citología , Regulador de Conductancia de Transmembrana de Fibrosis Quística/metabolismo , Células Caliciformes/metabolismo , Humanos , Inmunohistoquímica , Técnicas In Vitro , Mucosa Intestinal/citología , Técnicas de Placa-Clamp
8.
Conserv Biol ; 28(3): 641-5, 2014 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-24779392

RESUMEN

A divergence of values has become apparent in recent debates between conservationists who focus on ecosystem services that can improve human well-being and those who focus on avoiding the extinction of species. These divergent points of view fall along a continuum from anthropocentric to biocentric values, but most conservationists are relatively closer to each other than to the ends of the spectrum. We have some concerns with both positions but emphasize that conservation for both people and all other species will be most effective if conservationists focus on articulating the values they all share, being respectful of divergent values, and collaborating on common interests. The conservation arena is large enough to accommodate many people and organizations whose diverse values lead them to different niches that can, with good will and foresight, be far more complementary than competitive.


Asunto(s)
Biodiversidad , Conservación de los Recursos Naturales , Ecosistema , Humanos , Filosofía
9.
J Pathol ; 226(3): 463-70, 2012 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-22009605

RESUMEN

Diarrhoea in ulcerative colitis (UC) mainly reflects impaired colonic Na(+) and water absorption. Colonocyte membrane potential, an important determinant of electrogenic Na(+) absorption, is reduced in UC. Colonocyte potential is principally determined by basolateral IK (KCa3.1) channel activity. To determine whether reduced Na(+) absorption in UC might be associated with decreased IK channel expression and activity, we used molecular and patch clamp recording techniques to evaluate IK channels in colon from control patients and patients with active UC. In control patients, immunolabelling revealed basolateral IK channels distributed uniformly along the surface-crypt axis, with substantially decreased immunolabelling in patients with active UC, although IK mRNA levels measured by quantitative PCR were similar in both groups. Patch clamp analysis indicated that cell conductance was dominated by basolateral IK channels in control patients, but channel abundance and overall activity were reduced by 53% (p = 0.03) and 61% (p = 0.04), respectively, in patients with active UC. These changes resulted in a 75% (p = 0.003) decrease in the estimated basolateral membrane K(+) conductance in UC patients compared with controls. Levels of IK channel immunolabelling and activity in UC patients in clinical remission were similar to those in control patients. We conclude that a substantial decrease in basolateral IK channel expression and activity in active UC most likely explains the epithelial cell depolarization observed in this disease, and decreases the electrical driving force for electrogenic Na(+) transport, thereby impairing Na(+) absorption (and as a consequence, Cl(-) and water absorption) across the inflamed mucosa.


Asunto(s)
Colitis Ulcerosa/complicaciones , Diarrea/etiología , Canales de Potasio de Conductancia Intermedia Activados por el Calcio/metabolismo , Colitis Ulcerosa/metabolismo , Diarrea/metabolismo , Células Epiteliales/fisiología , Humanos , Inmunohistoquímica , Mucosa Intestinal/metabolismo , Potenciales de la Membrana/fisiología , Técnicas de Placa-Clamp , Reacción en Cadena de la Polimerasa , ARN Mensajero/metabolismo
10.
J Med Entomol ; 59(2): 725-740, 2022 03 16.
Artículo en Inglés | MEDLINE | ID: mdl-34958101

RESUMEN

In the United States, surveillance has been key to tracking spatiotemporal emergence of blacklegged ticks [Ixodes scapularis Say (Ixodida:Ixodidae)] and their pathogens such as Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner (Spirochaetales: Spirochaetaceae), the agent of Lyme disease. On the Holt Research Forest in midcoastal Maine, collection of feeding ticks from live-trapped small mammal hosts allowed us to track the emergence and establishment of I. scapularis, 1989-2019. From 1989-1995, we collected only I. angustus Neumann (Ixodida: Ixodidae)(vole tick), Dermacentor variabilis Say (Ixodida: Ixodidae) (American dog tick), and I. marxi Banks (Ixodida: Ixodidae) (squirrel tick) from seven species of small mammals. The most abundant tick host was the white-footed mouse [Peromyscus leucopus Rafinesque (Rodentia:Cricetidae)] followed by the red-backed vole (Myodes gapperi Vigors (Rodentia: Cricetidae)). Emergence of I. scapularis was signaled via the appearance of subadult I. scapularis in 1996. Emergence of B. burgdorferi was signaled through its appearance in I. scapularis feeding on mice in 2005. There was a substantial increase in I. scapularis prevalence (proportion of hosts parasitized) and burdens (ticks/host) on white-footed mice and red-backed voles in 2007. The ~11-yr time-to-establishment for I. scapularis was consistent with that seen in other studies. White-footed mice comprised 65.9% of all captures and hosted 94.1% of the total I. scapularis burden. The white-footed mouse population fluctuated interannually, but did not trend up as did I. scapularis prevalence and burdens. There were concurrent declines in I. angustus and D. variabilis. We discuss these results in the broader context of regional I. scapularis range expansion.


Asunto(s)
Borrelia burgdorferi , Enfermedades de los Perros , Ixodes , Ixodidae , Enfermedad de Lyme , Quercus , Rhipicephalus sanguineus , Enfermedades de los Roedores , Animales , Perros , Bosques , Enfermedad de Lyme/epidemiología , Maine , Peromyscus , Enfermedades de los Roedores/epidemiología
11.
Ecol Appl ; 21(4): 1283-95, 2011 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-21774430

RESUMEN

Conservation of forest amphibians is dependent on finding the right balance between management for timber production and meeting species' habitat requirements. For many pond-breeding amphibians, successful dispersal of the juvenile stage is essential for long-term population persistence. We investigated the influence of timber-harvesting practices on the movements of juvenile wood frogs (Lithobates sylvaticus). We used a chronosequence of stands produced by clear-cutting to evaluate how stand age affects habitat permeability to movements. We conducted experimental releases of juveniles in 2008 (n = 350) and 2009 (n = 528) in unidirectional runways in four treatments: mature forest, recent clearcut, 11-year-old, and 20-year-old regeneration. The runways were 50 x 2.5-m enclosures extending into each treatment, perpendicular to a distinct edge, with four tracking stations at 10, 20, 30, and 40 m from the edge. We recorded the number of animals reaching each tracking station, and the proportion of animals changing their direction of movement at each distance. We found that the mature forest was 3.1 and 3.7 times more permeable than the 11-year-old regeneration and the recent clearcut, respectively. Animals actively avoided open-canopy habitats and sharp edges; significantly more animals returned toward the closed-canopy forest at 0 m and 10 m in the less permeable treatments. There were no significant differences in habitat permeability between the mature forest and the 20-year-old regeneration. Our study is the first to directly assess habitat permeability to juvenile amphibian movement in relation to various forestry practices. We argue that habitat permeability at this scale is largely driven by the behavior of animals in relation to habitat disturbance and that caution needs to be used when using spatial modeling and expert-derived permeability values to assess connectivity of amphibian populations. The effects of clear-cutting on the migratory success of juvenile L. sylvaticus are long-lasting. Forestry practices that involve canopy removal and conversion of natural forest to conifer plantations may affect regional population viability by hindering successful dispersal.


Asunto(s)
Ecosistema , Agricultura Forestal/métodos , Ranidae/fisiología , Árboles/fisiología , Animales , Demografía , Maine , Factores de Tiempo
12.
Ambio ; 50(12): 2286-2310, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34657275

RESUMEN

Exploitation of natural forests forms expanding frontiers. Simultaneously, protected area frontiers aim at maintaining functional habitat networks. To assess net effects of these frontiers, we examined 16 case study areas on five continents. We (1) mapped protected area instruments, (2) assessed their effectiveness, (3) mapped policy implementation tools, and (4) effects on protected areas originating from their surroundings. Results are given as follows: (1) conservation instruments covered 3-77%, (2) effectiveness of habitat networks depended on representativeness, habitat quality, functional connectivity, resource extraction in protected areas, time for landscape restoration, "paper parks", "fortress conservation", and data access, (3) regulatory policy instruments dominated over economic and informational, (4) negative matrix effects dominated over positive ones (protective forests, buffer zones, inaccessibility), which were restricted to former USSR and Costa Rica. Despite evidence-based knowledge about conservation targets, the importance of spatial segregation of conservation and use, and traditional knowledge, the trajectories for biodiversity conservation were generally negative.


Asunto(s)
Conservación de los Recursos Naturales , Bosques , Biodiversidad , Costa Rica , Ecosistema
13.
Conserv Biol ; 24(6): 1459-68, 2010 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-20586789

RESUMEN

The search for generalities in ecology has often been thwarted by contingency and ecological complexity that limit the development of predictive rules. We present a set of concepts that we believe succinctly expresses some of the fundamental ideas in conservation biology. (1) Successful conservation management requires explicit goals and objectives. (2) The overall goal of biodiversity management will usually be to maintain or restore biodiversity, not to maximize species richness. (3) A holistic approach is needed to solve conservation problems. (4) Diverse approaches to management can provide diverse environmental conditions and mitigate risk. (5) Using nature's template is important for guiding conservation management, but it is not a panacea. (6) Focusing on causes not symptoms enhances efficacy and efficiency of conservation actions. (7) Every species and ecosystem is unique, to some degree. (8) Threshold responses are important but not ubiquitous. (9) Multiple stressors often exert critical effects on species and ecosystems. (10) Human values are variable and dynamic and significantly shape conservation efforts. We believe most conservation biologists will broadly agree these concepts are important. That said, an important part of the maturation of conservation biology as a discipline is constructive debate about additional or alternative concepts to those we have proposed here. Therefore, we have established a web-based, online process for further discussion of the concepts outlined in this paper and developing additional ones.


Asunto(s)
Conservación de los Recursos Naturales/métodos , Modelos Organizacionales , Objetivos Organizacionales
15.
Funct Plant Biol ; 47(4): 355-367, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-32130871

RESUMEN

Drought is a major constraint to canola production around the world. There is potential for improving crop performance in dry environments by selecting for transpiration efficiency (TE). In this work we investigated TE by studying its genetic association with carbon isotope discrimination (Δ) and other traits, e.g. specific leaf weight (SLW) and leaf chlorophyll content (SPAD). Among the 106 canola genotypes - including open-pollinated, hybrid, inbred types and cytoplasmic variants - tested in the field and glasshouse there was significant genotypic variation for TE, Δ, plant total dry weight, SLW and SPAD. Strong negative correlations were observed between TE and Δ (-0.52 to -0.76). Negative correlations between Δ and SLW or SPAD (-0.43 to -0.78) and smaller but significant positive correlations between TE and SLW or SPAD (0.23 to 0.30) suggested that photosynthetic capacity was, in part, underpinning the variation in TE. A cytoplasmic contribution to genetic variation in TE or Δ in canola was also observed with Triazine tolerant types having low TE and high Δ. This study showed that Δ has great potential for selecting canola germplasm with improved TE.


Asunto(s)
Brassica napus , Transpiración de Plantas , Brassica napus/genética , Isótopos de Carbono , Variación Genética , Hojas de la Planta/genética
16.
Ecol Lett ; 11(1): 78-91, 2008 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-17927771

RESUMEN

The management of landscapes for biological conservation and ecologically sustainable natural resource use are crucial global issues. Research for over two decades has resulted in a large literature, yet there is little consensus on the applicability or even the existence of general principles or broad considerations that could guide landscape conservation. We assess six major themes in the ecology and conservation of landscapes. We identify 13 important issues that need to be considered in developing approaches to landscape conservation. They include recognizing the importance of landscape mosaics (including the integration of terrestrial and aquatic areas), recognizing interactions between vegetation cover and vegetation configuration, using an appropriate landscape conceptual model, maintaining the capacity to recover from disturbance and managing landscapes in an adaptive framework. These considerations are influenced by landscape context, species assemblages and management goals and do not translate directly into on-the-ground management guidelines but they should be recognized by researchers and resource managers when developing guidelines for specific cases. Two crucial overarching issues are: (i) a clearly articulated vision for landscape conservation and (ii) quantifiable objectives that offer unambiguous signposts for measuring progress.


Asunto(s)
Conservación de los Recursos Naturales/métodos , Ambiente , Ecosistema , Modelos Biológicos
17.
Ecology ; 89(9): 2563-74, 2008 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-18831177

RESUMEN

To predict the effects of terrestrial habitat change on amphibian populations, we need to know how amphibians respond to habitat heterogeneity, and whether habitat choice remains consistent throughout the life-history cycle. We conducted four experiments to evaluate how the spatial distribution of juvenile wood frogs, Rana sylvatica (including both overall abundance and localized density), was influenced by habitat choice and habitat structure, and how this relationship changed with spatial scale and behavioral phase. The four experiments included (1) habitat manipulation on replicated 10-ha landscapes surrounding breeding pools; (2) short-term experiments with individual frogs emigrating through a manipulated landscape of 1 m wide hexagonal patches; and habitat manipulations in (3) small (4-m2); and (4) large (100-m2) enclosures with multiple individuals to compare behavior both during and following emigration. The spatial distribution of juvenile wood frogs following emigration resulted from differences in the scale at which juvenile amphibians responded to habitat heterogeneity during active vs. settled behavioral phases. During emigration, juvenile wood frogs responded to coarse-scale variation in habitat (selection between 2.2-ha forest treatments) but not to fine-scale variation. After settling, however, animals showed habitat selection at much smaller scales (2-4 m2). This resulted in high densities of animals in small patches of suitable habitat where they experienced rapid mortality. No evidence of density-dependent habitat selection was seen, with juveniles typically choosing to remain at extremely high densities in high-quality habitat, rather than occupying low-quality habitat. These experiments demonstrate how prediction of the terrestrial distribution of juvenile amphibians requires understanding of the complex behavioral responses to habitat heterogeneity. Understanding these patterns is important, given that human alterations to amphibian habitats may generate extremely high densities of animals, resulting in high density-dependent mortality.


Asunto(s)
Ecosistema , Metamorfosis Biológica , Ranidae/fisiología , Animales , Densidad de Población
18.
J Steroid Biochem Mol Biol ; 104(1-2): 45-52, 2007 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-17184988

RESUMEN

Aldosterone produces rapid, non-genomic, inhibition of basolateral intermediate conductance K(+) (IK(Ca)) channels in human colonic crypt cells but the intracellular second messengers involved are unclear. We therefore evaluated the role of protein kinase C (PKC) in aldosterone's non-genomic inhibitory effect on basolateral IK(Ca) channels in crypt cells from normal human sigmoid colon. Patch clamp studies revealed that in cell-attached patches, IK(Ca) channel activity decreased progressively to 38+/-8% (P<0.001) of the basal value 10 min after the addition of 1 nmol/L aldosterone, and decreased further to 23+/-6% (P<0.02) of the basal value 5 min after increasing the aldosterone concentration to 10 nmol/L. Pre-incubation of crypts with 1 micromol/L chelerythrine chloride or 1 micromol/L Gö 6976 (PKC inhibitors) prevented the inhibitory effect of aldosterone. Conversely, channel activity decreased to 60+/-9% (P<0.02) of the basal value 10 min after the addition of 500 nmol/L PMA (a PKC activator), whereas 4alpha-PMA (an inactive ester) had no effect. When aldosterone (10 nmol/L) and PMA were added together, IK(Ca) channel activity was inhibited to the same extent as with aldosterone alone. These results indicate that aldosterone's non-genomic inhibitory effect on the macroscopic basolateral K(+) conductance in human colonic crypts reflects PKC-mediated inhibition of IK(Ca) channels.


Asunto(s)
Aldosterona/farmacología , Colon/efectos de los fármacos , Canales de Potasio de Conductancia Intermedia Activados por el Calcio/efectos de los fármacos , Proteína Quinasa C-alfa/fisiología , Adulto , Alcaloides/farmacología , Antineoplásicos/farmacología , Benzofenantridinas/farmacología , Carcinógenos/farmacología , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Colon/metabolismo , Células Epiteliales/efectos de los fármacos , Células Epiteliales/metabolismo , Humanos , Canales de Potasio de Conductancia Intermedia Activados por el Calcio/metabolismo , Mucosa Intestinal/efectos de los fármacos , Mucosa Intestinal/metabolismo , Activación del Canal Iónico/efectos de los fármacos , Técnicas de Placa-Clamp , Bloqueadores de los Canales de Potasio/farmacología , Acetato de Tetradecanoilforbol/farmacología
19.
Conserv Biol ; 21(5): 1218-29, 2007 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-17883487

RESUMEN

Relatively few studies have examined the ecological effects of group-selection timber harvesting, and nearly all have been short-term and have lacked experimental manipulations that allow pre- and posttreatment comparisons. We have been documenting the effects of a group-selection timber harvest on bird abundance in a Maine forest for 24 years (preharvest, 1983-1987; postharvest, 1988-2006). Here we characterized the trends in bird abundance over the first 20 years of the study in the managed and control halves of the 40-ha study area. Species responses to the group-selection harvest were idiosyncratic, but in general the mature-forest bird community was retained and species dependent on early successional habitat temporarily (

Asunto(s)
Aves/fisiología , Conservación de los Recursos Naturales , Ecosistema , Agricultura Forestal/métodos , Árboles , Animales , Dinámica Poblacional , Factores de Tiempo
20.
Biochim Biophys Acta ; 1566(1-2): 152-61, 2002 Nov 13.
Artículo en Inglés | MEDLINE | ID: mdl-12421546

RESUMEN

Two-pore domain K(+) (K2P) channels have been cloned from a variety of species and tissues. They have been characterised biophysically as a 'background' K(+)-selective conductance and are gated by pH, stretch, heat, coupling to G-proteins and anaesthetics. Whilst their precise physiological function is unknown, they are likely to represent an increasingly important family of membrane proteins.


Asunto(s)
Proteínas de la Membrana/química , Canales de Potasio de Dominio Poro en Tándem , Canales de Potasio/química , Secuencia de Aminoácidos , Anestésicos/farmacología , Animales , Técnicas Biosensibles , Encéfalo/efectos de los fármacos , Química Encefálica , Clonación Molecular , Conductividad Eléctrica , Corazón/efectos de los fármacos , Humanos , Potenciales de la Membrana , Datos de Secuencia Molecular , Miocardio/química , Proteínas del Tejido Nervioso/química , Proteínas del Tejido Nervioso/efectos de los fármacos , Canales de Potasio/análisis , Canales de Potasio/efectos de los fármacos , Canales de Potasio/genética , Estructura Terciaria de Proteína
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