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[PMID]: 29411793
[Au] Autor:Berger M; Chen Y; Bampali K; Ernst M; Maulide N
[Ad] Address:Institute of Organic Chemistry, University of Vienna, Währinger Straße 38, 1090 Vienna, Austria. nuno.maulide@univie.ac.at.
[Ti] Title:Expeditious synthesis of polyacetylenic water hemlock toxins and their effects on the major GABA receptor isoform.
[So] Source:Chem Commun (Camb);54(16):2008-2011, 2018 Feb 20.
[Is] ISSN:1364-548X
[Cp] Country of publication:England
[La] Language:eng
[Ab] Abstract:Classical synthetic approaches to highly unsaturated polyene/yne natural products rely on iterative cross-coupling of linear fragments. Herein, we present an expeditious and unified approach to the unsaturated backbone of polyacetylenes via domino cuprate addition/4π-electrocyclic ring opening of a stereodefined cyclobutene intermediate. This sets the stage for a detailed biological assessment of the role of Virol A and Cicutoxin as inhibitors of GABA induced chloride currents, providing further insight into the interaction of these highly potent toxins towards the GABA receptor, including the structure-activity relationship of the derivatives.
[Pt] Publication type:JOURNAL ARTICLE
[Em] Entry month:1802
[Cu] Class update date: 180220
[Lr] Last revision date:180220
[St] Status:In-Process
[do] DOI:10.1039/c7cc09801d

  2 / 523 MEDLINE  
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[PMID]: 29362885
[Au] Autor:Schaeffer RN; Wang Z; Thornber CS; Preisser EL; Orians CM
[Ad] Address:Department of Biology, Tufts University, Medford, MA, 02155, USA. robert.schaeffer@wsu.edu.
[Ti] Title:Two invasive herbivores on a shared host: patterns and consequences of phytohormone induction.
[So] Source:Oecologia;, 2018 Jan 23.
[Is] ISSN:1432-1939
[Cp] Country of publication:Germany
[La] Language:eng
[Ab] Abstract:Herbivore-induced changes in host quality mediate indirect interactions between herbivores. The nature of these indirect interactions can vary depending on the identity of herbivores involved, species-specific induction of defense-signaling pathways, and sequence of attack. However, our understanding of the role of these signaling pathways in the success of multiple exotic herbivores is less known. Eastern hemlock (Tsuga canadensis) is attacked by two invasive herbivores [elongate hemlock scale (EHS; Fiorinia externa) and hemlock woolly adelgid (HWA; Adelges tsugae)] throughout much of its range, but prior attack by EHS is known to deter HWA. The potential role of phytohormones in this interaction is poorly understood. We measured endogenous levels of phytohormones in eastern hemlock in response to attack by these invasive herbivores. We also used exogenous application of methyl jasmonate (MJ) and acibenzolar-S-methyl (ASM), a salicylic acid (SA) pathway elicitor, to test the hypothesis that defense-signaling phytohormones typically induced by herbivores could deter HWA. Resistance to adelgid attack was assessed using a behavioral assay. Adelgid feeding significantly elevated both abscisic acid (ABA) and SA in local tissues, while EHS feeding had no detectable effect on either phytohormone. HWA progrediens and sistens crawlers preferred to settle on ASM-treated foliage. In contrast, HWA crawlers actively avoided settlement on MJ-treated foliage. We suggest that induction of ABA- and SA-signaling pathways, in concert with defense-signaling interference, may aid HWA invasion success, and that defense-signaling interference, induced by exotic competitors, may mediate resistance of native hosts.
[Pt] Publication type:JOURNAL ARTICLE
[Em] Entry month:1801
[Cu] Class update date: 180124
[Lr] Last revision date:180124
[St] Status:Publisher
[do] DOI:10.1007/s00442-018-4063-0

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[PMID]: 29135964
[Au] Autor:Hotti H; Rischer H
[Ad] Address:VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, 02044 Espoo, Finland. hannu.hotti@gmail.com.
[Ti] Title:The killer of Socrates: Coniine and Related Alkaloids in the Plant Kingdom.
[So] Source:Molecules;22(11), 2017 Nov 14.
[Is] ISSN:1420-3049
[Cp] Country of publication:Switzerland
[La] Language:eng
[Ab] Abstract:Coniine, a polyketide-derived alkaloid, is poisonous to humans and animals. It is a nicotinic acetylcholine receptor antagonist, which leads to inhibition of the nervous system, eventually causing death by suffocation in mammals. Coniine's most famous victim is Socrates who was sentenced to death by poison chalice containing poison hemlock in 399 BC. In chemistry, coniine holds two historical records: It is the first alkaloid the chemical structure of which was established (in 1881), and that was chemically synthesized (in 1886). In plants, coniine and twelve closely related alkaloids are known from poison hemlock ( L.), and several and species. Recent work confirmed its biosynthetic polyketide origin. Biosynthesis commences by carbon backbone formation from butyryl-CoA and two malonyl-CoA building blocks catalyzed by polyketide synthase. A transamination reaction incorporates nitrogen from l-alanine and non-enzymatic cyclization leads to γ-coniceine, the first hemlock alkaloid in the pathway. Ultimately, reduction of γ-coniceine to coniine is facilitated by NADPH-dependent γ-coniceine reductase. Although coniine is notorious for its toxicity, there is no consensus on its ecological roles, especially in the carnivorous pitcher plants where it occurs. Lately there has been renewed interest in coniine's medical uses particularly for pain relief without an addictive side effect.
[Pt] Publication type:JOURNAL ARTICLE; REVIEW
[Em] Entry month:1711
[Cu] Class update date: 171114
[Lr] Last revision date:171114
[St] Status:In-Process

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[PMID]: 28791805
[Au] Autor:Mech AM; Harper SJ; Havill NP; von Dohlen CD; Burke GR
[Ad] Address:Department of Entomology, University of Georgia, Athens, Georgia, USA.
[Ti] Title:Ecological factors influencing the beneficial endosymbionts of the hemlock woolly adelgid (Hemiptera: Adelgidae).
[So] Source:Insect Sci;, 2017 Aug 09.
[Is] ISSN:1744-7917
[Cp] Country of publication:Australia
[La] Language:eng
[Ab] Abstract:Bacterial endosymbionts of sap-sucking insects provide their host with a number of beneficial qualities, including the supply of nutrition, defense against parasitoids, and protection from heat stress. Damage to these bacterial associates can therefore have a negative impact on the fitness of their insect host. We evaluated observational and experimental factors regarding the nonnative hemlock woolly adelgid (Adelges tsugae Annand) (Hemiptera: Adelgidae) to help understand the roles of its three recently identified symbionts, including under heat stress conditions. The prevalence of A. tsugae's facultative symbiont (Serratia symbiotica) was examined at different spatial scales to determine how variable infection rates are for this symbiont. There was no significant difference found in infection rates between adelgids on a tree, within a plot, or within a state. However, significantly more adelgids in Georgia (95%) had S. symbiotica compared to those in New York (68%). Microsatellite genotyping of the adelgids found that this difference was most likely not the result of a second introduction of A. tsugae into eastern North America. Comparison of S. symbiotica proportions between first and fourth instars showed that symbiont absence did not affect the ability of A. tsugae to survive aestivation. Evaluations of symbiont densities within each adelgid found that when S. symbiotica was absent, the density of obligate symbionts was significantly higher. Exposure to heat stress (32.5 °C) was not consistently correlated with changes in symbiont densities over a 4-d period. Overall, we have shown that symbiont prevalence and densities vary within the broad population of A. tsugae in eastern North America, with potentially significant effects upon the ecology of this important pest.
[Pt] Publication type:JOURNAL ARTICLE
[Em] Entry month:1708
[Cu] Class update date: 170927
[Lr] Last revision date:170927
[St] Status:Publisher
[do] DOI:10.1111/1744-7917.12514

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[PMID]: 28770052
[Au] Autor:Lombardo JA; Elkinton JS
[Ad] Address:Department of Environmental ConservationUniversity of MassachusettsAmherstMAUSA.
[Ti] Title:Environmental adaptation in an asexual invasive insect.
[So] Source:Ecol Evol;7(14):5123-5130, 2017 Jul.
[Is] ISSN:2045-7758
[Cp] Country of publication:England
[La] Language:eng
[Ab] Abstract:Parthenogenetic reproduction is generally associated with low genetic variance and therefore reduced ability for environmental adaptation, and this could limit the potential invasiveness of introduced species that reproduce asexually. However, the hemlock woolly adelgid is an asexual invasive insect that has spread across a large geographic temperature gradient in its introduced range. Consequently, this insect has shown significant variation in cold hardiness among populations. We hypothesized that the increased cold hardiness of northern populations represents an adaptation to the colder temperatures. To test this, we collected individual adelgid from populations spanning their invaded range and inoculated them into a common thermal environment. We then experimentally sampled the supercooling point of the progeny of these adelgids and compared these results with tests of the supercooling point of adelgid sampled directly from their source populations. The results showed that the same significant differences in supercooling that was found among geographically distinct populations existed even when the adelgid was reared in a common environment, indicating a genetic basis for the variation in cold hardiness. These findings support the hypothesis that the adelgid has adapted to the colder environment as it has expanded its distribution in its invaded range.
[Pt] Publication type:JOURNAL ARTICLE
[Em] Entry month:1708
[Cu] Class update date: 170807
[Lr] Last revision date:170807
[St] Status:PubMed-not-MEDLINE
[do] DOI:10.1002/ece3.2894

  6 / 523 MEDLINE  
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[PMID]: 28608930
[Au] Autor:Benton EP; Grant JF; Nichols RJ; Webster RJ; Schwartz JS; Bailey JK
[Ad] Address:Department of Entomology and Plant Pathology, The University of Tennessee, Knoxville, Tennessee, USA.
[Ti] Title:Risk assessment of imidacloprid use in forest settings on the aquatic macroinvertebrate community.
[So] Source:Environ Toxicol Chem;36(11):3108-3119, 2017 Nov.
[Is] ISSN:1552-8618
[Cp] Country of publication:United States
[La] Language:eng
[Ab] Abstract:The isolated effects of a single insecticide can be difficult to assess in natural settings because of the presence of numerous pollutants in many watersheds. Imidacloprid use for suppressing hemlock woolly adelgid, Adelges tsugae (Annand) (Hemiptera: Adelgidae), in forests offers a rare opportunity to assess potential impacts on aquatic macroinvertebrates in relatively pristine landscapes. Aquatic macroinvertebrate communities were assessed in 9 streams in Great Smoky Mountains National Park (southern Appalachian Mountains, USA). The streams flow through hemlock conservation areas where imidacloprid soil drench treatments were applied for hemlock woolly adelgid suppression. Sites were located upstream and downstream of the imidacloprid treatments. Baseline species presence data (pre-imidacloprid treatment) were available from previous sample collections at downstream sites. Downstream and upstream sites did not vary in numerous community measures. Although comparisons of paired upstream and downstream sites showed differences in diversity in 7 streams, higher diversity was found more often in downstream sites. Macroinvertebrate functional feeding groups and life habits were similar between downstream and upstream sites. Downstream and baseline stream samples were similar. While some functional feeding group and life habit species richness categories varied, variations did not indicate poorer quality downstream communities. Imidacloprid treatments applied according to US Environmental Protection Agency federal restrictions did not result in negative effects to aquatic macroinvertebrate communities, which indicates that risks of imidacloprid use in forest settings are low. Environ Toxicol Chem 2017;36:3108-3119. © 2017 SETAC.
[Pt] Publication type:JOURNAL ARTICLE
[Em] Entry month:1706
[Cu] Class update date: 171027
[Lr] Last revision date:171027
[St] Status:In-Process
[do] DOI:10.1002/etc.3887

  7 / 523 MEDLINE  
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[PMID]: 28444212
[Au] Autor:Mausel DL; Kok LT; Salom SM
[Ad] Address:Department of Entomology, Virginia Tech, 216A Price Hall MC 0319 Blacksburg, VA 24061-0002 (davidm@mtewood.com; ltkok@vt.edu; salom@vt.edu).
[Ti] Title:Numerical Response and Impact of Laricobius nigrinus (Coleoptera: Derodontidae) on Adelges tsugae (Hemiptera: Adelgidae) in Their Native Range.
[So] Source:Environ Entomol;46(3):544-551, 2017 06 01.
[Is] ISSN:1938-2936
[Cp] Country of publication:England
[La] Language:eng
[Ab] Abstract:To determine if key attributes for a successful biological control agent are possessed by the predator, Laricobius nigrinus Fender, field studies were conducted in its native range of Seattle, WA. The relationship between adult and immature L. nigrinus abundance to different densities of its prey, Adelges tsugae Annand, were determined. In a second study, predator and prey densities, and survivorship of each sistens A. tsugae stage were determined to gauge the impact of predation. The predator strongly aggregated and increased its reproduction when prey density increased, the two mechanisms of a numerical response. Immature predator-prey ratios were high and average prey density was low in comparison with invaded areas of the eastern United States. Survivorship of aestivating first-instar sistens A. tsugae was low and survivorship of each instar (second, third, and fourth) and adults was high and increased with each stage. When pooled, however, the survivorship of sistens second instar-ovisac stages was low primarily owing to L. nigrinus larval consumption of ovisacs. In its native range, L. nigrinus has key attributes of a successful biological control agent, such as a strong numerical response, high predator-prey ratios, and an important larval impact on A. tsugae populations. Demographic data could serve as important benchmarks for future studies to determine if L. nigrinus and other predators can regulate densities of A. tsugae below eastern hemlock's physiological damage threshold in the eastern United States.
[Mh] MeSH terms primary: Coleoptera/physiology
Food Chain
Predatory Behavior
[Mh] MeSH terms secundary: Animals
Coleoptera/growth & development
Hemiptera/growth & development
Larva/growth & development
Larva/physiology
Nymph/growth & development
Pest Control, Biological
Tsuga
Washington
[Pt] Publication type:JOURNAL ARTICLE; RESEARCH SUPPORT, U.S. GOV'T, NON-P.H.S.
[Em] Entry month:1707
[Cu] Class update date: 171126
[Lr] Last revision date:171126
[Js] Journal subset:IM
[Da] Date of entry for processing:170427
[St] Status:MEDLINE
[do] DOI:10.1093/ee/nvx078

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[PMID]: 28439394
[Au] Autor:Schaeffer RN; Soltis NE; Martin JL; Brown AL; Gómez S; Preisser EL; Orians CM
[Ad] Address:Department of Biology, Tufts University, Medford, MA 02155, USA.
[Ti] Title:Seasonal variation in effects of herbivory on foliar nitrogen of a threatened conifer.
[So] Source:AoB Plants;9(2):plx007, 2017 Mar.
[Is] ISSN:2041-2851
[Cp] Country of publication:England
[La] Language:eng
[Ab] Abstract:Invasive herbivores can dramatically impact the nitrogen (N) economy of native hosts. In deciduous species, most N is stored in stem tissues, while in evergreen conifer species N is stored in needles, making them potentially more vulnerable to herbivory. In eastern forests of the USA, the long-lived, foundational conifer eastern hemlock ( ) is under the threat of extirpation by the invasive hemlock woolly adelgid (HWA: ). We assessed the impact of HWA infestation on the patterns of seasonal foliar N availability in hemlock planted in a deciduous forest understory. Over the course of a year, we sampled needles and twigs and measured N, carbon (C), C:N ratio, and total protein concentrations. Tissue sampling events were timed to coincide with key life-history transitions for HWA to determine the association between HWA development and feeding with these foliar nutrients. In uninfested trees, needle and twig N concentrations fluctuated across seasons, indicating the potential importance of N storage and remobilization for the N economy of eastern hemlock. Although N levels in HWA-infested trees also cycled annually, the degree to which N concentrations fluctuated seasonally in tissues was significantly affected by HWA feeding. These fluctuations exceeded N levels observed in control trees and coincided with HWA feeding. HWA feeding generally increased N concentrations but did not affect protein levels, suggesting that changes in N do not occur via adelgid-induced protein breakdown. Herbivore-induced mobilization of N to feeding sites and its rapid depletion may be a significant contributor to eastern hemlock mortality in US forests.
[Pt] Publication type:JOURNAL ARTICLE
[Em] Entry month:1704
[Cu] Class update date: 170428
[Lr] Last revision date:170428
[St] Status:PubMed-not-MEDLINE
[do] DOI:10.1093/aobpla/plx007

  9 / 523 MEDLINE  
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[PMID]: 28422072
[Au] Autor:Letheren A; Hill S; Salie J; Parkman J; Chen J
[Ad] Address:Department of Public Health, The University of Tennessee, Knoxville, TN 37996, USA. alethere@vols.utk.edu.
[Ti] Title:A Little Bug with a Big Bite: Impact of Hemlock Woolly Adelgid Infestations on Forest Ecosystems in the Eastern USA and Potential Control Strategies.
[So] Source:Int J Environ Res Public Health;14(4), 2017 Apr 19.
[Is] ISSN:1660-4601
[Cp] Country of publication:Switzerland
[La] Language:eng
[Ab] Abstract:Hemlock woolly adelgid ( Annand, HWA) remains the single greatest threat to the health and sustainability of hemlock in the eastern USA. The loss of hemlock trees leads to further negative impacts on the diversity and stability of ecosystems in the eastern part of North America. It is, therefore, urgent to develop effective control measures to reduce HWA populations and promote overall hemlock health. Currently available individual and integrated approaches should continue to be evaluated in the laboratory and in the field along with the development of other new and innovative methods.
[Mh] MeSH terms primary: Ecosystem
Forests
Hemiptera/parasitology
Hemlock/parasitology
Herbivory/physiology
Insect Control
Tsuga/parasitology
[Mh] MeSH terms secundary: Animals
Hemiptera/physiology
United States
[Pt] Publication type:JOURNAL ARTICLE; REVIEW
[Em] Entry month:1705
[Cu] Class update date: 170530
[Lr] Last revision date:170530
[Js] Journal subset:IM
[Da] Date of entry for processing:170420
[St] Status:MEDLINE

  10 / 523 MEDLINE  
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[PMID]: 28325831
[Au] Autor:Johnson JS; Gaddis KD; Cairns DM; Konganti K; Krutovsky KV
[Ad] Address:Department of Geography, Texas A&M University, 810 Eller O&M Building, MS 3147 TAMU, College Station, Texas 77843-3147 USA jsjohnson@tamu.edu.
[Ti] Title:Landscape genomic insights into the historic migration of mountain hemlock in response to Holocene climate change.
[So] Source:Am J Bot;104(3):439-450, 2017 Mar.
[Is] ISSN:1537-2197
[Cp] Country of publication:United States
[La] Language:eng
[Ab] Abstract:PREMISE OF THE STUDY: Untangling alternative historic dispersal pathways in long-lived tree species is critical to better understand how temperate tree species may respond to climatic change. However, disentangling these alternative pathways is often difficult. Emerging genomic technologies and landscape genetics techniques improve our ability to assess these pathways in natural systems. We address the question to what degree have microrefugial patches and long-distance dispersal been responsible for the colonization of mountain hemlock ( ) on the Alaskan Kenai Peninsula. METHODS: We used double-digest restriction-associated DNA sequencing (ddRADseq) to identify genetic variants across eight mountain hemlock sample sites on the Kenai Peninsula, Alaska. We assessed genetic diversity and linkage disequilibrium using landscape and population genetics approaches. Alternative historic dispersal pathways were assessed using discriminant analysis of principle components and electrical circuit theory. KEY RESULTS: A combination of decreasing diversity, high gene flow, and landscape connectivity indicates that mountain hemlock colonization on the Kenai Peninsula is the result of long-distance dispersal. We found that contemporary climate best explained gene flow patterns and that isolation by resistance was a better model explaining genetic variation than isolation by distance. CONCLUSIONS: Our findings support the conclusion that mountain hemlock colonization is the result of several long-distance dispersal events following Pleistocene glaciation. The high dispersal capability suggests that mountain hemlock may be able to respond to future climate change and expand its range as new habitat opens along its northern distribution.
[Mh] MeSH terms primary: Gene Flow
Genetic Variation
Genomics
Hemlock/genetics
[Mh] MeSH terms secundary: Alaska
Climate
Climate Change
Ecosystem
Genetics, Population
Genotype
Hemlock/physiology
Linkage Disequilibrium
Sequence Analysis, DNA
Trees
[Pt] Publication type:JOURNAL ARTICLE
[Em] Entry month:1708
[Cu] Class update date: 170822
[Lr] Last revision date:170822
[Js] Journal subset:IM
[Da] Date of entry for processing:170323
[St] Status:MEDLINE
[do] DOI:10.3732/ajb.1600262


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