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Image correlation microscopy methodology was extended and used to determine retrospectively the density, dynamics and interactions of α5-integrin in migrating cells. α5-integrin is present in submicroscopic clusters containing 3-4 integrins before it is discernibly organized. The integrin in nascent adhesions, as identified by the presence of paxillin, is ∼1.4 times more concentrated, ∼4.5 times more clustered and much less mobile than in surrounding regions. Thus, while integrins are clustered throughout the cell, they differ in nascent adhesions and appear to initiate adhesion formation, despite their lack of visible organization. In more mature adhesions where the integrin is visibly organized there are ∼900 integrins μm–2 (about fivefold higher than surrounding regions). Interestingly, α5-integrin and α-actinin, but not paxillin, reside in a complex throughout the cell, where they diffuse and flow together, even in regions where they are not organized. During adhesion disassembly some integrins diffuse away slowly, α-actinin undergoes a directed movement at speeds similar to actin retrograde flow (0.29 μm min–1), while all of the paxillin diffuses away rapidly.

Bathymetric gradients of biodiversity in the deep-sea benthos constitute a major class of large-scale biogeographic phenomena. They are typically portrayed and interpreted as variation in alpha diversity (the number of species recovered in individual samples) along depth transects. Here, we examine the depth ranges of deep-sea gastropods and bivalves in the eastern and western North Atlantic. This approach shows that the abyssal molluscan fauna largely represents deeper range extensions for a subset of bathyal species. Most abyssal species have larval dispersal, and adults live at densities that appear to be too low for successful reproduction. These patterns suggest a new explanation for abyssal biodiversity. For many species, bathyal and abyssal populations may form a source-sink system in which abyssal populations are regulated by a balance between chronic extinction arising from vulnerabilities to Allee effects and immigration from bathyal sources. An increased significance of source-sink dynamics with depth may be driven by the exponential decrease in organic carbon flux to the benthos with increasing depth and distance from productive coastal systems. The abyss, which is the largest marine benthic environment, may afford more limited ecological and evolutionary opportunity than the bathyal zone.

ABSTRACT. Community-based monitoring (CBM) in the Arctic is gaining increasing support from a wide range of interested parties, including community members, scientists, government agencies, and funders. Through CBM initiatives, Arctic residents conduct or are involved in ongoing observing and monitoring activities. Arctic Indigenous peoples have been observing the environment for millennia, and CBM often incorporates traditional knowledge, which may be used independently from or in partnership with conventional scientific monitoring methods. Drawing on insights from the first Arctic Observing Summit, we provide an overview of the state of CBM in the Arctic. The CBM approach to monitoring is centered on community needs and interests. It offers fine-grained, local-scale data that are readily accessible to community and municipal decision makers. In spite of these advantages, CBM initiatives remain little documented and are often unconnected to wider networks, with the result that many practitioners lack a clear sense of the field and how best to support its growth and development. CBM initiatives are implemented within legal and governance frameworks that vary significantly both within and among different national contexts. Further documentation of differences and similarities among Arctic communities in relation to observing needs, interests, and legal and institutional capacities will help assess how CBM can contribute to Arctic observing networks. While CBM holds significant potential to meet observing needs of communities, more investment and experimentation are needed to determine how observations and data generated through CBM approaches might effectively inform decision making beyond the community level.Key words: community-based monitoring; traditional knowledge; observing networks; environmental change; sustainability; knowledge management; natural resource management RÉSUMÉ. Dans l'Arctique, la surveillance communautaire (SC) reçoit un appui de plus en plus grand de la part de nombreuses parties intéressées, dont les membres de la communauté, les scientifiques, les organismes gouvernementaux et les bailleurs de fonds. Dans le cadre des initiatives de SC, des habitants de l'Arctique effectuent des tâches permanentes d'observation et de surveillance ou participent à de telles tâches. Les peuples indigènes de l'Arctique observent l'environnement depuis des millénaires. Souvent, la SC fait appel aux connaissances traditionnelles, connaissances qui peuvent être employées seules ou conjointement avec les méthodes classiques de surveillance scientifique. Nous nous sommes appuyés sur les connaissances dérivées du premier sommet d'observation de l'Arctique pour donner un aperçu de l'état de la SC dans l'Arctique. La méthode de SC est centrée sur les besoins et les intérêts de la communauté. Elle permet d'obtenir des données à grain fin à l'échelle locale, données qui sont facilement accessibles par la communauté et les preneurs de décisions municipaux. Malgré ces avantages, il existe peu de documentation au sujet...

The Arctic is a sentinel of global change. This region is influenced by multiple physical and socio-economic drivers and feedbacks, impacting both the natural and human environment. Air pollution is one such driver that impacts Arctic climate change, ecosystems and health but significant uncertainties still surround quantification of these effects. Arctic air pollution includes harmful trace gases (e.g. tropospheric ozone) and particles (e.g. black carbon, sulphate) and toxic substances (e.g. polycyclic aromatic hydrocarbons) that can be transported to the Arctic from emission sources located far outside the region, or emitted within the Arctic from activities including shipping, power production, and other industrial activities. This paper qualitatively summarizes the complex science issues motivating the creation of a new international initiative, PACES (air Pollution in the Arctic: Climate, Environment and Societies). Approaches for coordinated, international and interdisciplinary research on this topic are described with the goal to improve predictive capability via new understanding about sources, processes, feedbacks and impacts of Arctic air pollution. Overarching research actions are outlined, in which we describe our recommendations for 1) the development of trans-disciplinary approaches combining social and economic research with investigation of the chemical and physical aspects Arctic air pollution: Challenges and opportunities for the next decade of Arctic air pollution; 2) increasing the quality and quantity of observations in the Arctic using long-term monitoring and intensive field studies, both at the surface and throughout the troposphere; and 3) developing improved predictive capability across a range of spatial and temporal scales. Domain Editor-in-Chief

As social insect workers mature, outside-nest tasks associated with foraging and defense are typically performed at higher frequencies. Foraging in ants is often a pheromonally mediated collective action performed by mature workers; age-dependent differences in olfactory response thresholds may therefore proximately regulate task repertoire development. In the ant Pheidole dentata, foraging activity increases with chronological age in minor workers, and is chemically controlled. The onset of foraging in minor workers is accompanied by marked neuroanatomical and neurochemical changes, including synaptic remodeling in olfactory regions of the brain, proliferation of serotonergic neurons, and increased brain titers of monoamines, notably serotonin. We examined the linkage of serotonin and olfactory responsiveness by assaying trail-following performance in mature P. dentata minor workers with normal serotonin levels, or serotonin levels experimentally lowered by oral administration of the serotonin synthesis inhibitor α-methyltryptophan (AMTP). By assessing responsiveness to standardized pheromone trails, we demonstrate that trail-following behaviors are significantly reduced in serotonin-depleted workers. AMTP-treated individuals were less likely to initiate trail following, and oriented along pheromone trails for significantly shorter distances than untreated, similar-age workers. These results demonstrate for the first time that serotonin modulates olfactory processes and/or motor functions associated with cooperative foraging in ants.

Recent attention to the role of Indigenous knowledge (IK) in environmental monitoring, research and decision‐making is likely to attract new people to this field of work. Advancing the bringing together of IK and science in a way that is desirable to IK holders can lead to successful and inclusive research and decision‐making. We used the Delphi technique with 18 expert participants who were IK holders or working closely with IK from across the Arctic to examine the drivers of progress and limitations to the use of IK along with science to inform decision‐making related to wildlife, reindeer herding and the environment. We also used this technique to identify participants' experiences of scientists' misconceptions concerning IK. Participants had a strong focus on transformative change relating to the structure of institutions, politics, rights, involvement, power and agency over technical issues advancing or limiting progress (e.g. new technologies and language barriers). Participants identified two modes of desirable research: coproducing knowledge with scientists and autonomous Indigenous‐led research. They highlighted the need for more collaborative and coproduction projects to allow further refinement of approaches and more funding to support autonomous, Indigenous‐led research. Most misconceptions held by scientists concerning IK that were identified by participants related to the spatial, temporal and conceptual scope of IK, and the perceived need to validate IK using Western science. Our research highlights some of the issues that need to be addressed by all participants in research and decision‐making involving IK and science. While exact approaches will need to be tailored to specific social‐ecological contexts, consideration of these broader concerns revealed by our analysis are likely to be central to effective partnerships. A free Plain Language Summary can be found within the Supporting Information of this article.

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