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To authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1600-0706.2010.18544.x Byline: Steven J. Presley, Christopher L. Higgins, Michael R. Willig Abstract: The metacommunity framework is a powerful platform for evaluating patterns of species distribution in geographic or environmental space. Idealized patterns (checkerboard, Clementsian, evenly spaced, Gleasonian and nested distributions) give the framework shape. Each pattern represents an area in a multidimensional continuum of metacommunity structures; however, the current approach to analysis of spatial structure of metacommunities is incomplete. To address this, we describe additional non-random structures and illustrate how they may be discerned via objective criteria. First, we distinguish three distinct forms of species loss in nested structures, which should improve identification of structuring mechanisms for nested patterns. Second, we define six quasi-structures that are consistent with the conceptual underpinnings of Clementsian, Gleasonian, evenly spaced and nested distributions. Finally, we demonstrate how combinations of structures at smaller spatial extents may aggregate to form Clementsian structure at larger extents. These refinements should facilitate the identification of best-fit patterns, associated structuring mechanisms, and informative scales of analysis and interpretation. This conceptual and analytical framework may be applied to network properties within communities (i.e. structure of interspecific interactions) and has broad application in ecology and biogeography. Author Affiliation: (1)Center for Environmental Sciences and Engineering and Dept of Ecology and Evolutionary Biology, Univ. of Connecticut, Storrs, CT 06269-4210, USA (2)Dept of Biological Sciences, Tarleton State Univ., Stephenville, TX 76402, USA Article History: Paper manuscript accepted 25 February 2010 Article note: S. J. Presley, Center for Environmental Sciences and Engineering and Dept of Ecology and Evolutionary Biology, Univ. of Connecticut, Storrs, CT 06269-4210, USA. E-mail: steven.presley@uconn.edu

Author(s): Christopher F. Higgins (corresponding author) [1, 2] The acquisition of multidrug resistance is a serious impediment to improved healthcare. Multidrug resistance is most frequently due to active transporters that [...]

Author(s): Christopher F. Higgins (corresponding author) [1, 2] The acquisition of multidrug resistance is a serious impediment to improved healthcare. Multidrug resistance is most frequently due to active transporters that [...]

To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.0030-1299.2007.15391.x Byline: Christopher P. Bloch, Christopher L. Higgins, Michael R. Willig Abstract: Distributions of species often exhibit nested structure, such that assemblages at species-poor sites are proper subsets of taxa at more species-rich sites. Traditionally, this has been viewed as a large-scale biogeographic pattern and treated implicitly as static from a temporal perspective. Nonetheless, recent work suggests that nestedness may arise at multiple spatio-temporal scales. A 13-year data set encompassing the effects of two large-scale natural disturbances (hurricanes Hugo and Georges) on terrestrial gastropod assemblages was used to test the hypothesis that changes in species composition resulting from disturbance alter the degree of nestedness exhibited over time at two spatial scales. Gastropod assemblages were least nested immediately following disturbance, and nestedness increased thereafter. Although land-use history influenced the degree of nestedness, trajectories of nestedness following disturbance were similar irrespective of disturbance history or hurricane identity. The effects of hurricanes with respect to nestedness of terrestrial gastropods may be general and predictable, even though species respond to hurricanes in disparate fashions. By damaging some localities within the forest more severely than others, a hurricane dismantles extant patterns of species composition and severs connections among sites, as inhospitable microclimatic conditions limit dispersal of gastropods. As time passes and the forest canopy regenerates, conditions ameliorate, and movement among sites becomes more frequent. Thus, a conclusion based on a single time period may not characterize the study system in general. Consequently, explanations for nested structure that incorporate variability in ecological as well as evolutionary time will improve the applicability and comparability of nested subsets analysis across study systems. Article History: Manuscript Accepted 24 October 2006 Article note: C. P. Bloch (cbloch@bridgew.edu), C. L. Higgins and M. R. Willig, Dept of Biological Sciences and The Museum, Texas Tech Univ., Lubbock, TX 79409-3131, USA. Present address for CPB: Dept of Biological Sciences, Bridgewater State College, Bridgewater, MA 02325, USA. Present address for CLH: Dept of Biological Sciences, Tarleton State Univ., Stephenville, TX 76402-0100, USA. Present address for MRW: Center for Environmental Sciences and Engineering and Dept of Ecology and Evolutionary Biology, Univ. of Connecticut, Storrs, CT 06269-5210, USA.

The effects of species-abundance distributions, island-size distributions, and total abundances on the degree of nestedness and its significance are examined. It is believed that stochastic processes, such as the random placement of individuals, predispose systems to evince patterns of nestedness at the species level, which might account, in part, for the ubiquity of nestedness in nature is shown.

Bacteria have developed antibiotic-resistance mechanisms, and LmrA, a protein in Lactococcus lactis, extrudes amphiphilic compounds from the cytoplasmic membrane, to mediate antibiotic resistance. LmrA is an ATP-binding cassette (ABC) transporter, along with the human multidrug-resistance P-glycoprotein. LmrA was expressed in human ling fibroblast cells, which was surprisingly targeted to the plasma membrane, conferring typical multi-drug resistance. Their pharmacological characteristics were similar and their affinity for vinblastine and magnesium-ATP was indistinguishable.

Enolase and RhlB, a member of the DEAD-box family of ATP-dependent RNA helicases, are novel components of RNA degradosome. RhlB most likely unwinds distinct RNA structures in the presence of ATP to facilitate mRNA degradation by PNPase as shown by the RNAs failure to degrade when RhlB is blocked by an affinity-purified antibody even if ATP is added. Enolase's purpose in degradosome is still unknown.

We commend the FluoroCouncil for phasing out long-chain poly- and perfluoroalkyl substance (PFAS) chemistry. However, members of the FluoroCouncil have been producing long-chain PFASs for decades while in possession of [...]

As scientists and other professionals from a variety of disciplines, we are concerned about the production and release into the environment of an increasing number of poly- and perfluoroalkyl substances [...]

There is a family of proteins that bind adenosine triphosphate (ATP), a molecule involved in the production of energy, which are also involved in the transport of molecules. This group of proteins includes molecules of bacteria involved in the uptake and export of molecules. In higher organisms, they include genes involved in resistance to multiple types of drugs used in tumor therapy; in resistance to the drug chloroquine in the malarial parasite; the transport of a yeast mating pheromone; and the gene that is defective in cystic fibrosis. Structural models are presented of these ATP-binding transport molecules. In almost 70 percent of the patients with cystic fibrosis, deletions are present in the areas of the gene that are involved in binding and degrading of ATP. Many of the symptoms of cystic fibrosis stem from abnormally thick secretions, especially in the lungs. These symptoms are related to a problem in the transport of chloride ions (electrically charged particles) across cellular membranes. Thus, it was thought that the defective gene in cystic fibrosis might encode a protein that works as a channel that ions pass through. However, some researchers believe that the defective protein in cystic fibrosis is not a channel for chloride molecules. Channels do not require the degradation of ATP. Chloride channels allow the flow of chloride ions in both directions, while the proteins that the gene involved in cystic fibrosis encodes only allow the flow of ions in one direction. Other evidence that indicates the gene does not code for a chloride channel includes: the size of the molecule, which is too large; chloride channels vary in different tissues, but there is only one defective gene in cystic fibrosis; and other characteristic sequences of chloride channels are not present. Therefore, it is thought that the protein is not a chloride channel, but may transport a molecule that regulates a chloride channel. (Consumer Summary produced by Reliance Medical Information, Inc.)

Summary: Per- and polyfluoroalkyl substances (PFASs) are man-made chemicals that contain at least one perfluoroalkyl moiety, -[C.sub.n][F.sub.2n]-. To date, over 4,000 unique PFASs have been used in technical applications and consumer products, and some of them have been detected globally in human and wildlife biomonitoring studies. Because of their extraordinary persistence, human and environmental exposure to PFASs will be a long-term source of concern. Some PFASs such as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) have been investigated extensively and thus regulated, but for many other PFASs, knowledge about their current uses and hazards is still very limited or missing entirely. To address this problem and prepare an action plan for the assessment and management of PFASs in the coming years, a group of more than 50 international scientists and regulators held a two-day workshop in November, 2017. The group identified both the respective needs of and common goals shared by the scientific and the policy communities, made recommendations for cooperative actions, and outlined how the science-policy interface regarding PFASs can be strengthened using new approaches for assessing and managing highly persistent chemicals such as PFASs. https://doi. org/10.1289/EHP4158, Introduction Per- and polyfluoroalkyl substances (PFASs) are a family of anthropogenic chemicals that contain at least one perfluoroalkyl moiety, -[C.sub.n][F.sub.2n]- (Buck et al. 2011; OECD 2018). Due to the thermal [...]

The common bacterium Escherichia coli and its bacterial viruses are well used in science research because they have ideal pathogenic, and nutritional characteristics. However, the functions of up to 40% of an estimated 4,288 genes in E. coli have not yet been established. Scientists need to launch a cooperative international research strategy to ascertain the bacterium's genetic makeup.