Distribution of duck broods relative to habitat characteristics in the Prairie Pothole Region

Conservation programs for breeding ducks in the Prairie Pothole Region (PPR) of the United States and Canada require effective means of evaluating and characterizing breeding habitat across large landscapes. Extensive surveys of the distribution of duck broods in late-summer could help identify wetland basins with greater probabilities of occupancy. Broods are difficult to detect, however, rendering presence–absence data from single-visit surveys difficult to interpret, particularly when probability of detection is related to habitat features. Multiple-visit occupancy surveys offer a potential solution. From 20 July to 5 August 2007–2009, we conducted a 3-visit survey of wetland basins located on 167 10.4-km² study plots in the PPR. Our survey focused on broods of the 5 most common breeding duck species (Anas spp.). Our main objectives were to investigate ecological relationships between occupancy of wetland basins by broods and habitat characteristics and to examine if habitat-specific detection was of enough concern to warrant multi-survey approaches in the future. We surveyed 3,226 wetland basins during the study. Probability of occupancy of a wetland basin by a brood was positively related to the log of wet area for all 5 study species and was greater on wetlands located on plots with a greater proportion of herbaceous perennial cover for 4 of 5 species. For example, the median probability of occupancy for gadwall (Anas strepera) increased from 0.08 (90% Credible Interval [CrI]: 0.07, 0.10) to 0.28 (90% CrI: 0.23, 0.33) as wet area increased from 0.19 ha to 2.12 ha, and increased from 0.12 (90% CrI: 0.09, 0.16) to 0.20 (90% CrI: 0.16, 0.25) as proportion of perennial grass cover on the study plot increased from 0.03 to 0.99. Because occupancy and detection were both related to attributes of wetland basins, we concluded that the multiple-visit survey was a useful approach for identifying habitat relationships of duck broods. Our results indicated that most broods of the study species were found in 10.4-km² landscapes with greater densities of small- to mid-sized wetland basins and a greater proportion of herbaceous perennial vegetation. Our study provided new empirical support that could be used to help target conservation actions to the most productive landscapes for breeding ducks. © 2012 The Wildlife Society.     

Neophylax kolodskii (Trichoptera: Uenoidae), A New Species from the Great Smoky Mountains National Park,U.S.A.

Neophylax kolodskii sp. n. from Great Smoky Mountains National Park is described and illustrated from adult specimens.     

Silent,generic and plant kairomone sensitive odorant receptors from the Southern house mosquito

The Southern house mosquito Culex quinquefasciatus has the largest repertoire of odorant receptors (ORs) of all mosquitoes and dipteran species whose genomes have been sequenced to date. Previously, we have identified and de-orphanized two ORs expressed in female antennae, CquiOR2 and CquiOR10, which are sensitive to oviposition attractants. In view of a new nomenclature for the Culex genome (VectorBase) we renamed these ORs as CquiOR21 (formerly CquiOR10) and CquiOR121 (CquiOR2). In addition, we selected ORs from six different phylogenetic groups for deorphanization. We cloned four of them by using cDNA from female antennae as a template. Attempts to clone CquiOR87 and CquiOR110 were unsuccessful either because they are pseudogenes or are not expressed in adult female antennae, the main olfactory tissue. By contrast, CquiOR1, CquiOR44, CquiOR73, and CquiOR161 were highly expressed in female antennae. To de-orphanize these ORs, we employed the Xenopus oocyte recording system. CquiORx–CquiOrco-expressed oocytes were challenged with a panel of 90 compounds, including known oviposition attractants, human and vertebrate host odorants, plant kairomones, and naturally occurring repellents. While CquiOR161 did not respond to any test compound in two different laboratories, CquiOR1 showed the features of a generic OR, with strong responses to 1-octen-3-ol and other ligands. CquiOR44 and CquiOR73 showed preference to plant-derived terpenoids and phenolic compounds, respectively. While fenchone was the best ligand for the former, 3,5-dimethylphenol elicited the strongest responses in the latter. The newly de-orphanized ORs may be involved in reception of plant kairomones and/or natural repellents.     

Enhanced hippocampus‐dependent memory and reduced anxiety in mice over‐expressing human catalase in mitochondria

Oxidative stress (OS) and reactive oxygen species (ROS) play a modulatory role in synaptic plasticity and signaling pathways. Mitochondria (MT), a major source of ROS because of their involvement in energy metabolism, are important for brain function. MT‐generated ROS are proposed to be responsible for a significant proportion of OS and are associated with developmental abnormalities and aspects of cellular aging. The role of ROS and MT function in cognition of healthy individuals is relatively understudied. In this study, we characterized behavioral and cognitive performance of 5‐ to 6‐month‐old mice over‐expressing mitochondrial catalase (MCAT). MCAT mice showed enhancements in hippocampus‐dependent spatial learning and memory in the water maze and contextual fear conditioning, and reduced measures of anxiety in the elevated zero maze. Catalase activity was elevated in MCAT mice in all brain regions examined. Measures of oxidative stress (glutathione, protein carbonyl content, lipid peroxidation, and 8‐hydroxyguanine) did not significantly differ between the groups. The lack of differences in these markers of oxidative stress suggests that the differences observed in this study may be due to altered redox signaling. Catalase over‐expression might be sufficient to enhance cognition and reduce measures of anxiety even in the absence of alteration in levels of OS.     

Three-Dimensional Structure of CAP-Gly Domain of Mammalian Dynactin Determined by Magic Angle Spinning NMR Spectroscopy: Conformational Plasticity and Interactions with End-Binding Protein EB1

Microtubules and their associated proteins play important roles in vesicle and organelle transport, cell motility and cell division. Perturbation of these processes by mutation typically gives rise to severe pathological conditions. In our efforts to obtain atomic information on microtubule-associated protein/microtubule interactions with the goal to understand mechanisms that might potentially assist in the development of treatments for these diseases, we have determined the three-dimensional structure of CAP-Gly (cytoskeleton-associated protein, glycine-rich) domain of mammalian dynactin by magic angle spinning NMR spectroscopy. We observe two conformations in the β2 strand encompassing residues T43-V44-A45, residues that are adjacent to the disease-associated mutation, G59S. Upon binding of CAP-Gly to microtubule plus-end tracking protein EB1, the CAP-Gly shifts to a single conformer. We find extensive chemical shift perturbations in several stretches of residues of CAP-Gly upon binding to EB1, from which we define accurately the CAP-Gly/EB1 binding interface. We also observe that the loop regions may exhibit unique flexibility, especially in the GKNDG motif, which participates in the microtubule binding. This study in conjunction with our previous reports suggests that conformational plasticity is an intrinsic property of CAP-Gly likely due to its unusually high loop content and may be required for its biological functions.     

Vitalism and the Resistance to Experimentation on Life in the Eighteenth Century

There is a familiar opposition between a ‘Scientific Revolution’ ethos and practice of experimentation, including experimentation on life, and a ‘vitalist’ reaction to this outlook. The former is often allied with different forms of mechanism – if all of Nature obeys mechanical laws, including living bodies, ‘iatromechanism’ should encounter no obstructions in investigating the particularities of animal-machines – or with more chimiatric theories of life and matter, as in the ‘Oxford Physiologists’. The latter reaction also comes in different, perhaps irreducibly heterogeneous forms, ranging from metaphysical and ethical objections to the destruction of life, as in Margaret Cavendish, to more epistemological objections against the usage of instruments, the ‘anatomical’ outlook and experimentation, e.g. in Locke and Sydenham. But I will mainly focus on a third anti-interventionist argument, which I call ‘vitalist’ since it is often articulated in the writings of the so-called Montpellier Vitalists, including their medical articles for the Encyclopédie. The vitalist argument against experimentation on life is subtly different from the metaphysical, ethical and epistemological arguments, although at times it may borrow from any of them. It expresses a Hippocratic sensibility – understood as an artifact of early modernity, not as some atemporal trait of medical thought – in which Life resists the experimenter, or conversely, for the experimenter to grasp something about Life, it will have to be without torturing or radically intervening in it. I suggest that this view does not have to imply that Nature is something mysterious or sacred; nor does the vitalist have to attack experimentation on life in the name of some ‘vital force’ – which makes it less surprising to find a vivisectionist like Claude Bernard sounding so close to the vitalists.     

Multiple C-Terminal Tails within a Single E. coli SSB Homotetramer Coordinate DNA Replication and Repair

Escherichia coli single-stranded DNA binding protein (SSB) plays essential roles in DNA replication, recombination and repair. SSB functions as a homotetramer with each subunit possessing a DNA binding domain (OB-fold) and an intrinsically disordered C-terminus, of which the last nine amino acids provide the site for interaction with at least a dozen other proteins that function in DNA metabolism. To examine how many C-termini are needed for SSB function, we engineered covalently linked forms of SSB that possess only one or two C-termini within a four-OB-fold “tetramer”. Whereas E. coli expressing SSB with only two tails can survive, expression of a single-tailed SSB is dominant lethal. E. coli expressing only the two-tailed SSB recovers faster from exposure to DNA damaging agents but accumulates more mutations. A single-tailed SSB shows defects in coupled leading and lagging strand DNA replication and does not support replication restart in vitro. These deficiencies in vitro provide a plausible explanation for the lethality observed in vivo. These results indicate that a single SSB tetramer must interact simultaneously with multiple protein partners during some essential roles in genome maintenance.     

Testing the Sulfotransferase Molecular Pore Hypothesis

Human cytosolic sulfotransferases (SULTs) regulate the activities of hundreds of signaling metabolites via transfer of the sulfuryl moiety (-SO₃) from activated sulfate (3′-phosphoadenosine 5′-phosphosulfate) to the hydroxyls and primary amines of xeno- and endobiotics. How SULTs select substrates from the scores of competing ligands present in a cytosolic milieu is an important issue in the field. Selectivity appears to be sterically controlled by a molecular pore that opens and closes in response to nucleotide binding. This point of view is fostered by structures showing nucleotide-dependent pore closure and the fact that nucleotide binding induces an isomerization that restricts access to the acceptor-binding pocket. Molecular dynamics models underscore the importance of pore isomerization in selectivity and predict that specific molecular linkages stabilize the closed pore in response to nucleotide binding. To test the pore model, these linkages were disrupted in SULT2A1 via mutagenesis, and the effects on selectivity were determined. The mutations uncoupled nucleotide binding from selectivity and produced enzymes that no longer discriminated between large and small substrates. The mutations did not affect the affinity or turnover of small substrates but resulted in a 183-fold gain in catalytic efficiently toward large substrates. Models predict that an 11-residue “flap” covering the acceptor-binding pocket can open and admit large substrates when nucleotide is bound; a mutant structure demonstrated that this is so. In summary, the model was shown to be a robust, accurate predictor of SULT structure and selectivity whose general features will likely apply to other members of the SULT family.