Red alder: A bibliography with abstracts

Treesearch

Charles F. Heebner; Mary Jane Bergener

1983-01-01

This bibliography lists 661 references to world literature through Hay 1978 containing information about red alder (Alnus rubra Bong.). Included are publications about its taxonomy, biology and silvics, chemical and physical information about its wood and fiber, studies on its nitrogen fixing properties, and reports on industrial uses and economic...

Occurrence, structure, and function of the nitrogen-fixing microsymbiont Frankia from nodules of Arizona alder [Abstract

Treesearch

J. O. Dawson; G. J. Gottfried; D. Hahn

2005-01-01

Actinorhizal plants are nodulated by the symbiotic, nitrogen-fixing actinomycete Frankia. The genus Alnus in the family Betulaceae is one of the 25 genera in 8 families of angiospermous plants that are actinorhizal. Arizona alder (Alnus oblongifolia Torr.) occurs in isolated populations associated with the...

Red alder kitchen cabinets—How does application of commercial stains influence customer choice?

Treesearch

David Nicholls; Joseph Roos

2007-01-01

A better understanding of consumer reaction and preferences for red alder (Alnus rubra Bong.) secondary products will help Alaska producers in entering new markets. In this study, red alder kitchen cabinets were commercially stained to six different levels and displayed at home shows in Portland, Oregon, and Anchorage, Alaska. The stains simulated...

Growth and development of red alder compared with conifers in 30-year-old stands.

Treesearch

Carl M. Berntsen

1961-01-01

Red alder (Alnus rubra), although a widespread tree species in Pacific coast forests, has only in recent years attained commercial importance as a source of wood material for diversified products including furniture, paneling, and paper pulp. With the rapid increase in the harvest of red alder, both public agencies and private industry are making a...

An evaluation of the grades and value of red alder lumber in southeast Alaska

Treesearch

Allen M. Brackley; David Nicholls; Michael Hannan

2009-01-01

Many stands in southeast Alaska harvested since 1950, especially where there has been a high degree of disturbance of mineral soil, have regenerated to red alder (Alnus rubra Bong.) and are now approaching maturity. The availability of red alder raises questions addressed in this study about the recovery of lumber from this resource. Information in...

Character-marked furniture made from red alder harvested in southeast Alaska: product perspectives from consumers and retailers

Treesearch

Matthew Bumgardner; Nicholls David; Valerie Barber

2009-01-01

In recent decades, red alder (Alnus rubra Bong.) has become an important Pacific Northwest hardwood in appearance-grade lumber markets, such as exports, furniture, and cabinets. However, red alder generally is a short-lived pioneer species, and small logs can result in proportionally large volumes of lower grade...

Chemical basal treatment to control red alder.

Treesearch

Robert H. Ruth; Carl M. Berntsen

1956-01-01

A key to better restocking of conifers on recently cutover forest land in the Oregon Coast Range is the elimination of competition from red alder (Alnus rubra Bong.). This can be readily accomplished with a foliage spray containing 2,4-dichlorophenoxyacetic acid (2.4-D). Tests in 1954 and 1955 on the Cascade Head Experimental Forest have shown that...

Character-marked furniture made from red alder harvested in southeast Alaska: product perspectives from consumers and retailers

Treesearch

Matthew Bumgardner; David Nicholls; Valerie Barber

2009-01-01

In recent decades. red alder (Alnus rubra Bong.) has become an important Pacific Northwest hardwood in appearance-grade lumber markets, such as exports, furniture, and cabinets. However, red alder generally is a short-lived pioneer species, and small logs can result in proportionally large volumes of lower grade lumber containing numerous visual...

A 20-year growth record for three stands of red alder.

Treesearch

Carl M. Berntsen

1962-01-01

Until very recently, only fragmentary growth information has been available for red alder (Alnus rubra). This gap has now been partially closed through the preparation of normal yield tabled based on temporary sample plot data collected in northwestern Oregon, western Washington, and southern British Columbia.

Migration Patterns of Subgenus Alnus in Europe since the Last Glacial Maximum: A Systematic Review

PubMed Central

Douda, Jan; Doudová, Jana; Drašnarová, Alena; Kuneš, Petr; Hadincová, Věroslava; Krak, Karol; Zákravský, Petr; Mandák, Bohumil

2014-01-01

Background/Aims Recently, new palaeoecological records supported by molecular analyses and palaeodistributional modelling have provided more comprehensive insights into plant behaviour during the last Quaternary cycle. We reviewed the migration history of species of subgenus Alnus during the last 50,000 years in Europe with a focus on (1) a general revision of Alnus history since the Last Glacial Maximum (LGM), (2) evidence of northern refugia of Alnus populations during the LGM and (3) the specific history of Alnus in particular European regions. Methodology We determined changes in Alnus distribution on the basis of 811 and 68 radiocarbon-dated pollen and macrofossil sites, respectively. We compiled data from the European Pollen Database, the Czech Quaternary Palynological Database, the Eurasian Macrofossil Database and additional literature. Pollen percentage thresholds indicating expansions or retreats were used to describe patterns of past Alnus occurrence. Principal Findings An expansion of Alnus during the Late Glacial and early Holocene periods supports the presence of alders during the LGM in southern peninsulas and northerly areas in western Europe, the foothills of the Alps, the Carpathians and northeastern Europe. After glaciers withdrew, the ice-free area of Europe was likely colonized from several regional refugia; the deglaciated area of Scandinavia was likely colonized from a single refugium in northeastern Europe. In the more northerly parts of Europe, we found a scale-dependent pattern of Alnus expansion characterised by a synchronous increase of Alnus within individual regions, though with regional differences in the times of the expansion. In southern peninsulas, the Alps and the Carpathians, by contrast, it seems that Alnus expanded differently at individual sites rather than synchronously in whole regions. Conclusions Our synthesis supports the idea that northern LGM populations were important sources of postglacial Alnus expansion. The

Taper equation and volume tables for plantation-grown red alder.

Treesearch

Andrew A. Bluhm; Sean M. Garber; David E. Hibbs

2007-01-01

A taper equation and associated tables are presented for red alder (Alnus rubra Bong.) trees grown in plantations. The data were gathered from variable-density experimental plantations throughout the Pacific Northwest. Diameter inside bark along the stem was fitted to a variable exponent model form by using generalized nonlinear least squares and a...

Factors affecting distribution of wood, detritus, and sediment in headwater streams draining managed young-growth red alder-conifer forests in southeast Alaska

Treesearch

Takashi Gomi; Adelaide C. Johnson; Robert L. Deal; Paul E. Hennon; Ewa H. Orlikowska; Mark S. Wipfli

2006-01-01

Factors (riparian stand condition, management regimes, and channel properties) affecting distributions of wood, detritus (leaves and branches), and sediment were examined in headwater streams draining young-growth red alder (Alnus rubra Bong.)-conifer riparian forests (40 years old) in southeast Alaska. More riparian red alder were found along...

A method of site quality evaluation for red alder.

Treesearch

Constance A. Harrington

1986-01-01

A field guide to predict site index for red alder (Alnus rubra Bong.) was developed for use in western Washington and Oregon. The guide requires the user to evaluate 14 soil-site properties that are grouped into three general factors: (1) geographic and topographic position, (2) soil moisture and aeration during the growing season, and (3) soil fertility and physical...

Comparative effects of urea fertilizer and red alder in a site III, coast Douglas-fir plantation in the Washington Cascade Range.

Treesearch

Richard E. Miller; Harry W. Anderson; Marshall Murray; Rick. Leon

2005-01-01

Five randomly assigned treatments were used to quantify effects of adding varying numbers of red alder (Alnus rubra Bong.) or nitrogen (N) fertilization on growth of a 10-year-old conifer plantation at a medium quality site in the western Washington Cascade Range. Zero, 20, 40, and 80 alder trees per acre were retained along with about 300 conifers...

WATERSHED BIOGEOCHEMISTRY IN THE OREGON COAST RANGE: THE ROLE OF RED ALDER AND SALMON

EPA Science Inventory

Variations in plant community composition across the landscape can influence nutrient retention and loss at the watershed scale. A striking example of plant species influence is the role of N2-fixing red alder (Alnus rubra) in the biogeochemistry of Pacific Northwest forests. T...

Developing Biomass Equations for Western Hemlock and Red Alder Trees in Western Oregon Forests

Treesearch

Krishna Poudel; Hailemariam Temesgen

2016-01-01

Biomass estimates are required for reporting carbon, assessing feedstock availability, and assessing forest fire threat. We developed diameter- and height-based biomass equations for Western hemlock (Tsuga heterophylla (Raf.) Sarg.) and red alder (Alnus rubra Bong.) trees in Western Oregon. A system of component biomass...

Greenhouse germination trials of pelletized western redcedar and red alder seeds

Treesearch

Nabil Khadduri

2007-01-01

Pelletized western redcedar (Thuja plicata Donn ex D. Don) and red alder (Alnus rubra Bong.) seeds exhibited lower total germination and delayed germination speed (G50 or days to 50% germination) when compared to non-pelletized “raw” seeds in greenhouse trials. Averaged across two lots of western redcedar, pelletizing decreased...

Alnus acuminata in dual symbiosis with Frankia and two different ectomycorrhizal fungi (Alpova austroalnicola and Alpova diplophloeus) growing in soilless growth medium

Treesearch

Alejandra G. Becerra; Euginia Menoyo; Irene Lett; Ching Y. Li

2009-01-01

In this study we investigated the capacity of Andean alder (Alnus acuminata Kunth), inoculated with Frankia and two ectomycorrhizal fungi (Alpova austroalnicola Dominguez and Alpova diplophloeus [Zeller and Dodge] Trappe and Smith), for nodulation and growth in pots of a soilless medium...

Net degradation of methyl mercury in alder swamps.

PubMed

Kronberg, Rose-Marie; Tjerngren, Ida; Drott, Andreas; Björn, Erik; Skyllberg, Ulf

2012-12-18

Wetlands are generally considered to be sources of methyl mercury (MeHg) in northern temperate landscapes. However, a recent input-output mass balance study during 2007-2010 revealed a black alder (Alnus glutinosa) swamp in southern Sweden to be a consistent and significant MeHg sink, with a 30-60% loss of MeHg. The soil pool of MeHg varied substantially between years, but it always decreased with distance from the stream inlet to the swamp. The soil MeHg pool was significantly lower in the downstream as compared to the upstream half of the swamp (0.66 and 1.34 ng MeHg g⁻¹ SOC⁻¹ annual average⁻¹, respectively, one-way ANOVA, p = 0.0006). In 2008 a significant decrease of %MeHg in soil was paralleled by a significant increase in potential demethylation rate constant (k(d), p < 0.02 and p < 0.004, respectively). In contrast, the potential methylation rate constant (k(m)) was unrelated to distance (p = 0.3). Our results suggest that MeHg was net degraded in the Alnus swamp, and that it had a rapid and dynamic internal turnover of MeHg. Snapshot stream input-output measurements at eight additional Alnus glutinosa swamps in southern Sweden indicate that Alnus swamps in general are sinks for MeHg. Our findings have implications for forestry practices and landscape planning, and suggest that restored or preserved Alnus swamps may be used to mitigate MeHg produced in northern temperate landscapes.

Consumer preferences for kitchen cabinets made from red alder: a comparison to other hardwoods.

Treesearch

David L. Nicholls; Geoffrey H. Donovan; Joseph Roos

2004-01-01

In Alaska, red alder (Alnus rubra Bong.) is an abundant but commercially underutilized species despite having properties suitable for higher value products, including furniture and cabinetry. However, it laces the name recognition of mote traditional hardwoods. Our research measured the effect of this lack of familiarity on consumer preferences...

Limited evaluation of physical and mechanical properties of Nepal alder grown in Hawaii

Treesearch

C. C. Gerhards

1964-01-01

Nepal alder (Alnus nepalensis ) grown in Hawaii was evaluated for shrinkage, strength in bending, and hardness. This Hawaii-grown wood was comparable in bending strength to wood of the same species grown in Bengal, India, but was lower in modulus of elasticity and exhibited greater hardness and shrinkage. It was also harder than such Mainland species as aspen (Populus...

NITROGEN EXPORT FROM FORESTED WATERSHEDS IN THE OREGON COAST RANGE: THE ROLE OF N2-FIXING RED ALDER

EPA Science Inventory

Variations in plant community composition across the landscape can influence nutrient retention and loss at the watershed scale. A striking example of plant species influence is the role of N2-fixing red alder (Alnus rubra) in the biogeochemistry of Pacific Northwest forests. T...

Variation in damage from growing-season frosts among open-pollinated families of red alder.

Treesearch

Kevin C. Peeler; Dean S. DeBell

1987-01-01

Repeated growing-season frosts during late April and early May 1985 caused extensive damage to red alder (Alnus rubra Bong.) seedlings in a newly planted research trial in western Washington. About two-thirds of the seedlings were severely damaged (entire stem damaged or necrotic). Such damage varied by family, from 50 percent of seedlings in the...

Relations between red alder composition and understory vegetation in young mixed forests of southeast Alaska.

Treesearch

Thomas A. Hanley; Robert L. Deal; Ewa H. Orlikowska

2006-01-01

Interest in mixed red alder (Alnus rubra Bong.)—conifer young-growth stands has grown in southeast Alaska, USA, because they appear to provide much more productive understory vegetation and wildlife habitat than do similar-aged pure conifer stands. We studied understory vegetation in nine even-aged young-growth stands (38-42 years old)...

Size of Douglas-fir trees in relation to distance from a mixed red alder - Douglas-fir stand

Treesearch

R.E. Miller; D.L. Reukema; T.A. Max

1993-01-01

Variation in diameter, height, and stem volume of 57-year-old Douglas-fir(Pseudotsuga menziesii var. menziesii (Mirb.) Franco) was related to distance of these trees from a 27 m wide strip in the same Douglas-fir plantation that had been interplanted with red alder (Alnus rubra Bong.). Within the...

Morphological measurements and ITS sequences show that the new alder rust in Europe is conspecific with Melampsoridium hiratsukanum in eastern Asia.

PubMed

Hantula, J; Kurkela, T; Hendry, S; Yamaguchi, T

2009-01-01

Three species of Melampsoridium have been reported to infect hosts in genus Alnus. An epidemic of foliar rust affecting A. glutinosa and A. incana began in Europe in the mid-1990s, and the associated pathogen was identified as Melampsoridium hiratsukanum based on morphology. In this investigation we analyzed the morphology and genetic variation of alder rusts from Europe and Japan and the host specificity of the European epidemic rust. Our results showed that two rusts occur on the leaves of alders native to northern Europe; in Scotland an endemic rust indistinguishable from M. betulinum occurs, whereas alders in areas of Europe affected by the current epidemic were infected by M. hiratsukanum. M. hiratsukanum from naturally infected alder in Finland produced aecia on all Larix species tested but did not infect Betula leaves.

Influence of red alder on chemical properties of a clay loam soil in western Washington.

Treesearch

D.S. DeBell; M.A. Radwan; J.M. Kraft

1983-01-01

Chemical characteristics of mineral soil beneath red alder (Alnus rubra Bong.) stands of various ages were studied. Total nitrogen (N) of the 0-to 20-centimeter (0- to 8-inch) soil layer increased with stand age, and pH of both the 0- to 20-centimeter and 20- to 50-centimeter (8- to 20-inch) layers decreased with stand age. Contents of some mineral...

How Does Salinity Shape Bacterial and Fungal Microbiomes of Alnus glutinosa Roots?

PubMed Central

Thiem, Dominika; Gołębiewski, Marcin; Hulisz, Piotr; Piernik, Agnieszka; Hrynkiewicz, Katarzyna

2018-01-01

Black alder (Alnus glutinosa Gaertn.) belongs to dual mycorrhizal trees, forming ectomycorrhizal (EM) and arbuscular (AM) root structures, as well as represents actinorrhizal plants that associate with nitrogen-fixing actinomycete Frankia sp. We hypothesized that the unique ternary structure of symbionts can influence community structure of other plant-associated microorganisms (bacterial and fungal endophytes), particularly under seasonally changing salinity in A. glutinosa roots. In our study we analyzed black alder root bacterial and fungal microbiome present at two forest test sites (saline and non-saline) in two different seasons (spring and fall). The dominant type of root microsymbionts of alder were ectomycorrhizal fungi, whose distribution depended on site (salinity): Tomentella, Lactarius, and Phialocephala were more abundant at the saline site. Mortierella and Naucoria (representatives of saprotrophs or endophytes) displayed the opposite tendency. Arbuscular mycorrhizal fungi belonged to Glomeromycota (orders Paraglomales and Glomales), however, they represented less than 1% of all identified fungi. Bacterial community structure depended on test site but not on season. Sequences affiliated with Rhodanobacter, Granulicella, and Sphingomonas dominated at the saline site, while Bradyrhizobium and Rhizobium were more abundant at the non-saline site. Moreover, genus Frankia was observed only at the saline site. In conclusion, bacterial and fungal community structure of alder root microsymbionts and endophytes depends on five soil chemical parameters: salinity, phosphorus, pH, saturation percentage (SP) as well as total organic carbon (TOC), and seasonality does not appear to be an important factor shaping microbial communities. Ectomycorrhizal fungi are the most abundant symbionts of mature alders growing in saline soils. However, specific distribution of nitrogen-fixing Frankia (forming root nodules) and association of arbuscular fungi at early stages of

How Does Salinity Shape Bacterial and Fungal Microbiomes of Alnus glutinosa Roots?

PubMed

Thiem, Dominika; Gołębiewski, Marcin; Hulisz, Piotr; Piernik, Agnieszka; Hrynkiewicz, Katarzyna

2018-01-01

Black alder ( Alnus glutinosa Gaertn.) belongs to dual mycorrhizal trees, forming ectomycorrhizal (EM) and arbuscular (AM) root structures, as well as represents actinorrhizal plants that associate with nitrogen-fixing actinomycete Frankia sp. We hypothesized that the unique ternary structure of symbionts can influence community structure of other plant-associated microorganisms (bacterial and fungal endophytes), particularly under seasonally changing salinity in A. glutinosa roots. In our study we analyzed black alder root bacterial and fungal microbiome present at two forest test sites (saline and non-saline) in two different seasons (spring and fall). The dominant type of root microsymbionts of alder were ectomycorrhizal fungi, whose distribution depended on site (salinity): Tomentella , Lactarius , and Phialocephala were more abundant at the saline site. Mortierella and Naucoria (representatives of saprotrophs or endophytes) displayed the opposite tendency. Arbuscular mycorrhizal fungi belonged to Glomeromycota (orders Paraglomales and Glomales), however, they represented less than 1% of all identified fungi. Bacterial community structure depended on test site but not on season. Sequences affiliated with Rhodanobacter , Granulicella , and Sphingomonas dominated at the saline site, while Bradyrhizobium and Rhizobium were more abundant at the non-saline site. Moreover, genus Frankia was observed only at the saline site. In conclusion, bacterial and fungal community structure of alder root microsymbionts and endophytes depends on five soil chemical parameters: salinity, phosphorus, pH, saturation percentage (SP) as well as total organic carbon (TOC), and seasonality does not appear to be an important factor shaping microbial communities. Ectomycorrhizal fungi are the most abundant symbionts of mature alders growing in saline soils. However, specific distribution of nitrogen-fixing Frankia (forming root nodules) and association of arbuscular fungi at early stages

The patterns of Corylus and Alnus pollen seasons and pollination periods in two Polish cities located in different climatic regions.

PubMed

Puc, Małgorzata; Kasprzyk, Idalia

2013-01-01

This study compares phenological observations of Corylus (hazel) and Alnus (alder) flowering with airborne pollen counts of these taxa recorded using volumetric spore traps (2009-2011). The work was carried out in the Polish cities of Szczecin and Rzeszów that are located in different climatic regions. Correlations between pollen concentrations and meteorological data were investigated using Spearman's rank correlation analysis. The timings of hazel and alder pollination and the occurrence of airborne pollen varied greatly and were significantly influenced by meteorological conditions ( p  < 0.05). The flowering synchronization of hazel and alder pollination in Szczecin and Rzeszów varied over the study period. Hazel and alder trees flowered notably earlier in stands located in places that were exposed to sunlight (insolated) and sheltered from the wind. On the other hand, a delay in the timing of pollination was observed in quite sunny but very windy sites. In Rzeszów, maximum hazel pollen concentrations did not coincide with the period of full pollination (defined as between 25 % hazel and alder and 75 % of flowers open). Conversely, in Szczecin, the highest hazel pollen concentrations were recorded during phenophases of the full pollination period. The period when the highest alder pollen concentrations were recorded varied between sites, with Rzeszów recording the highest concentrations at the beginning of pollination and Szczecin recording alder pollen throughout the full pollination period. Substantial amounts of hazel and alder pollen grains were recorded in the air of Rzeszów (but not Szczecin) before the onset of the respective pollen seasons.

The Phytophthora species assemblage and diversity in riparian alder ecosystems of western Oregon, USA.

PubMed

Sims, Laura Lee; Sutton, Wendy; Reeser, Paul; Hansen, Everett M

2015-01-01

Phytophthora species were systematically sampled, isolated, identified and compared for presence in streams, soil and roots of alder (Alnus species) dominated riparian ecosystems in western Oregon. We describe the species assemblage and evaluate Phytophthora diversity associated with alder. We recovered 1250 isolates of 20 Phytophthora species. Only three species were recovered from all substrates (streams, soil, alder roots): P. gonapodyides, the informally described "P. taxon Pgchlamydo", and P. siskiyouensis. P. alni ssp. uniformis along with five other species not previously recovered in Oregon forests are included in the assemblage: P.citricola s.l., P. gregata, P. gallica, P. nicotianae and P. parsiana. Phytophthora species diversity was greatest in downstream riparian locations. There was no significant difference in species diversity comparing soil and unwashed roots (the rhizosphere) to stream water. There was a difference between the predominating species from the rhizosphere compared to stream water. The most numerous species was the informally described "P. taxon Oaksoil", which was mainly recovered from, and most predominant in, stream water. The most common species from riparian forest soils and alder root systems was P. gonapodyides. © 2015 by The Mycological Society of America.

Actinorhizal Alder Phytostabilization Alters Microbial Community Dynamics in Gold Mine Waste Rock from Northern Quebec: A Greenhouse Study

PubMed Central

Callender, Katrina L.; Roy, Sébastien; Khasa, Damase P.; Whyte, Lyle G.; Greer, Charles W.

2016-01-01

Phytotechnologies are rapidly replacing conventional ex-situ remediation techniques as they have the added benefit of restoring aesthetic value, important in the reclamation of mine sites. Alders are pioneer species that can tolerate and proliferate in nutrient-poor, contaminated environments, largely due to symbiotic root associations with the N2-fixing bacteria, Frankia and ectomycorrhizal (ECM) fungi. In this study, we investigated the growth of two Frankia-inoculated (actinorhizal) alder species, A. crispa and A. glutinosa, in gold mine waste rock from northern Quebec. Alder species had similar survival rates and positively impacted soil quality and physico-chemical properties in similar ways, restoring soil pH to neutrality and reducing extractable metals up to two-fold, while not hyperaccumulating them into above-ground plant biomass. A. glutinosa outperformed A. crispa in terms of growth, as estimated by the seedling volume index (SVI), and root length. Pyrosequencing of the bacterial 16S rRNA gene for bacteria and the ribosomal internal transcribed spacer (ITS) region for fungi provided a comprehensive, direct characterization of microbial communities in gold mine waste rock and fine tailings. Plant- and treatment-specific shifts in soil microbial community compositions were observed in planted mine residues. Shannon diversity and the abundance of microbes involved in key ecosystem processes such as contaminant degradation (Sphingomonas, Sphingobium and Pseudomonas), metal sequestration (Brevundimonas and Caulobacter) and N2-fixation (Azotobacter, Mesorhizobium, Rhizobium and Pseudomonas) increased over time, i.e., as plants established in mine waste rock. Acetate mineralization and most probable number (MPN) assays showed that revegetation positively stimulated both bulk and rhizosphere communities, increasing microbial density (biomass increase of 2 orders of magnitude) and mineralization (five-fold). Genomic techniques proved useful in investigating

Comparison of 226Ra nuclide from soil by three woody species Betula pendula, Sambucus nigra and Alnus glutinosa during the vegetation period.

PubMed

Soudek, Petr; Petrová, Sárka; Benesová, Dagmar; Tykva, Richard; Vanková, Radomíra; Vanek, Tomás

2007-01-01

The uptake of 226Ra from the contaminated soil was compared in three woody species: alder (Alnus glutinosa), birch (Betula pendula) and elder (Sambucus nigra). The 226Ra activities increased during the vegetation periods (in 2003, 2004 and 2005) both in the leaves and flowers+seeds. The highest accumulation was found in birch, reaching 0.41 Bq/g DW in the leaves (at the end of the vegetation period in 2003). The lowest 226Ra accumulation was determined in alder. The extent of 226Ra accumulation in the leaves of woody species demonstrates that these pioneer woody species can be used as remediation alternative to the use of herbs, provided that the removal of fallen leaves could be achieved in the end of vegetation period.

Density and rectangularity of planting influence 20-year growth and development of red alder.

Treesearch

Dean S. DeBell; Constance A. Harrington

2002-01-01

Red alder (Alnus rubra Bong.) seedlings were planted in northwestern Oregon, U.S.A., at five initial spacings: 0.6 × 1.2 m, 1.2 × 1.2 m, 1.2 × 1.8 m, 1.8 × 1.8 m, and 2.5 × 2.5 m. Up to about age 10, tree and stand characteristics were correlated primarily with initial planting density in the expected manner; through age 20, however, tree growth...

Factors affecting distribution of wood, detritus, and sediment in headwater streams draining managed young-growth red alder - Conifer forests in southeast Alaska

USGS Publications Warehouse

Gomi, T.; Johnson, A.C.; Deal, R.L.; Hennon, P.E.; Orlikowska, E.H.; Wipfli, M.S.

2006-01-01

Factors (riparian stand condition, management regimes, and channel properties) affecting distributions of wood, detritus (leaves and branches), and sediment were examined in headwater streams draining young-growth red alder (Alnus rubra Bong.) - conifer riparian forests (40 years old) remained in channels and provided sites for sediment and organic matter storage. Despite various alder-conifer mixtures and past harvesting effects, the abundance of large wood, fine wood, and detritus accumulations significantly decreased with increasing channel bank-full width (0.5-3.5 m) along relatively short channel distances (up to 700 m). Changes in wood, detritus, and sediment accumulations together with changes in riparian stand characteristics create spatial and temporal variability of in-channel conditions in headwater systems. A component of alder within young-growth riparian forests may benefit both wood production and biological recovery in disturbed headwater stream channels. ?? 2006 NRC.

Headwater riparian invertebrate communities associated with red alder and conifer wood and leaf litter in southeastern Alaska

USGS Publications Warehouse

LeSage, C.M.; Merritt, R.W.; Wipfli, M.S.

2005-01-01

We examined how management of young upland forests in southeastern Alaska affect riparian invertebrate taxa richness, density, and biomass, in turn, potentially influencing food abundance for fish and wildlife. Southeastern Alaska forests are dominated by coniferous trees including Sitka spruce (Picea sitchensis (Bong.) Carr.), western hemlock (Tsuga heterophylla (Raf.) Sarg.), with mixed stands of red cedar (Thuja plicata Donn.). Red alder (Alnus rubra Bong.) is hypothesized to influence the productivity of young-growth conifer forests and through forest management may provide increased riparian invertebrate abundance. To compare and contrast invertebrate densities between coniferous and alder riparian habitats, leaf litter and wood debris (early and late decay classes) samples were collected along eleven headwater streams on Prince of Wales Island, Alaska, during the summers of 2000 and 2001. Members of Acarina and Collembola were the most abundant taxa collected in leaf litter with alder litter having significantly higher mean taxa richness than conifer litter. Members of Acarina were the most abundant group collected on wood debris and alder wood had significantly higher mean taxa richness and biomass than conifer wood. Alder wood debris in more advanced decay stages had the highest mean taxa richness and biomass, compared to other wood types, while conifer late decay wood debris had the highest densities of invertebrates. The inclusion of alder in young-growth conifer forests can benefit forest ecosystems by enhancing taxa richness and biomass of riparian forest invertebrates. ?? 2005 by the Northwest Scientific Association. All rights reserved.

Mixed, short rotation culture of red alder and black cottonwood: growth, coppicing, nitrogen fixation, and allelopathy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heilman, P.; Stettler, R.F.

1985-01-01

Alnus rubra seedlings were grown in a 1:1 mixture at a spacing of 1.2 x 1.2 m with 28 Populus clones (25 clones pf P. trichocarpa, 2 of P. deltoides x P. trichocarpa, and one P. deltoides x P. nigra) in a study established in W. Washington in March 1979. Trees were harvested at 4 yr old. At harvest, average heights were: pure Populus, 10.2 m; Populus in the mixed stand 11.0 m; and alder 8.4 m. Most Populus sprouted satisfactorily after harvest (6.6 shoots/plant when pure, 7.6 shoots/plant in the mixture), but alder sprouted poorly (3.6 shoots/plant). Above-ground biomassmore » at harvest was 15.9 t/ha p.a. for the mixture and 16.7 t/ha p.a. for pure Populus, although the mixture had been more productive at 2 yr. Nitrogenase activity (nitrogen fixation as measured by acetylene reduction) of alder declines in the 4th season; competition was the most important factor influencing this decline. Soil N content had no effect on fixation. A pot study showed that ground Populus leaf and litter material inhibited the growth of red alder seedlings, although soil collected from Populus plots had no effect. Results indicated that allelopathy is probably a minor factor under field conditions, at most, and that growing mixed stands may, on balance, be beneficial. 20 references.« less

Early wide spacing in red alder (Alnus rubra Bong.): effects on stem form and stem growth.

Treesearch

Bernard T. Bormann

1985-01-01

A thinning trial was established in 1962 in a 7-year-old red alder stand in northwestern Washington. Spacings were 8 x 8 ft (dense), 12 x 12 it (intermediate), and 16 x 16 ft (open). The effect of early thinning on growth and stem form was measured in 1982, 20 years after spacing treatment. There was negligible tree lean and sweep in open and intermediate stands except...

Ecotoxicological effects evoked in hydrophytes by leachates of invasive Acer negundo and autochthonous Alnus glutinosa fallen off leaves during their microbial decomposition.

PubMed

Krevš, Alina; Darginavičienė, Jūratė; Gylytė, Brigita; Grigutytė, Reda; Jurkonienė, Sigita; Karitonas, Rolandas; Kučinskienė, Alė; Pakalnis, Romas; Sadauskas, Kazys; Vitkus, Rimantas; Manusadžianas, Levonas

2013-02-01

Throughout 90-day biodegradation under microaerobic conditions, invasive to Lithuania species boxelder maple (Acer negundo) leaves lost 1.5-fold more biomass than that of autochthonous black alder (Alnus glutinosa), releasing higher contents of N(tot), ammonium and generating higher BOD(7). Boxelder maple leaf leachates were characterized by higher total bacterial numbers and colony numbers of heterotrophic and cellulose-decomposing bacteria than those of black alder. The higher toxicity of A. negundo aqueous extracts and leachates to charophyte cell (Nitellopsis obtusa), the inhabitant of clean lakes, were manifested at mortality and membrane depolarization levels, while the effect on H(+)-ATPase activity in membrane preparations from the same algae was stronger in case of A. glutinosa. Duckweed (Lemna minor), a bioindicator of eutrophic waters, was more sensitive to leaf leachates of A. glutinosa. Fallen leaves and leaf litter leachates from invasive and native species of trees, which enter water body, affect differently microbial biodestruction and aquatic vegetation in freshwater systems. Copyright © 2012 Elsevier Ltd. All rights reserved.

Can We Use Tree Rings of Black Alder to Reconstruct Lake Levels? A Case Study for the Mecklenburg Lake District, Northeastern Germany

PubMed Central

van der Maaten, Ernst; van der Maaten-Theunissen, Marieke; Buras, Allan; Scharnweber, Tobias; Simard, Sonia; Kaiser, Knut; Lorenz, Sebastian; Wilmking, Martin

2015-01-01

In this study, we explore the potential to reconstruct lake-level (and groundwater) fluctuations from tree-ring chronologies of black alder (Alnus glutinosa L.) for three study lakes in the Mecklenburg Lake District, northeastern Germany. As gauging records for lakes in this region are generally short, long-term reconstructions of lake-level fluctuations could provide valuable information on past hydrological conditions, which, in turn, are useful to assess dynamics of climate and landscape evolution. We selected black alder as our study species as alder typically thrives as riparian vegetation along lakeshores. For the study lakes, we tested whether a regional signal in lake-level fluctuations and in the growth of alder exists that could be used for long-term regional hydrological reconstructions, but found that local (i.e. site-specific) signals in lake level and tree-ring chronologies prevailed. Hence, we built lake/groundwater-level reconstruction models for the three study lakes individually. Two sets of models were considered based on (1) local tree-ring series of black alder, and (2) site-specific Standardized Precipitation Evapotranspiration Indices (SPEI). Although the SPEI-based models performed statistically well, we critically reflect on the reliability of these reconstructions, as SPEI cannot account for human influence. Tree-ring based reconstruction models, on the other hand, performed poor. Combined, our results suggest that, for our study area, long-term regional reconstructions of lake-level fluctuations that consider both recent and ancient (e.g., archaeological) wood of black alder seem extremely challenging, if not impossible. PMID:26317768

Stream and floodplain restoration in a riparian ecosystem disturbed by placer mining

USGS Publications Warehouse

Karle, Kenneth F.; Densmore, Roseann V.

1994-01-01

Techniques for the hydrologic restoration of placer-mined streams and floodplains were developed in Denali National Park and Preserve Alaska, USA. The hydrologic study focused on a design of stream and floodplain geometry using hydraulic capacity and shear stress equations. Slope and sinuosity values were based on regional relationships. Design requirements include a channel capacity for a 1.5-year (bankfull) discharge and a floodplain capacity for a 1.5- to 100-year discharge. Concern for potential damage to the project from annual flooding before natural revegetation occurs led to development of alder (Alnus crispa) brush bars to dissipate floodwater energy and encourage sediment deposition. The brush bars, constructed of alder bundles tied together and anchored laterally adjacent to the channel, were installed on the floodplain in several configurations to test their effectiveness. A moderate flood near the end of the two-year construction phase of the project provided data on channel design, stability, floodplain erosion, and brush bar effectiveness. The brush bars provided substantial protection, but unconsolidated bank material and a lack of bed armour for a new channel segment led to some bank erosion, slope changes and an increase in sinuosity in several reaches of the study area.

Immunomodulatory effect of an isolated fraction from Tinospora crispa on intracellular expression of INF-γ, IL-6 and IL-8.

PubMed

Abood, Walaa Najm; Fahmi, Iman; Abdulla, Mahmood Ameen; Ismail, Salmah

2014-06-27

Immunomodulators are substances that modify immune system response to a threat. Immunomodulators modulate and potentiate the immune system, keeping it highly prepared for any threat. The immunomodulatory effect of the traditional medicine Tinospora crispa is investigated in this work. T. crispa ethanol extract was fractionated by using different solvents. The ethanol extract and effective isolated fraction were used to investigate the potential immunomodulatory effect of different T. crispa doses ranging from 25 μg/mL to 1000 μg/mL on RAW 246.7 cells by detecting intracellular INF-γ, IL-6, and IL-8 expressions. The antioxidant activity of T. crispa was evaluated through FRAP and DPPH. The total phenolic and total flavonoid contents were also quantified. Results show that T. crispa extract has higher antioxidant potential than ascorbic acid. The FRAP value of T. crispa extract is 11011.11 ± 1145.42 μmol Fe(+2)/g, and its DPPH inhibition percentage is 55.79 ± 7.9, with 22 μg/mL IC50. The results also reveal that the total phenolic content of T. crispa extract is 213.16- ± 1.31 mg GAE/g dry stem weight, and the total flavonoid content is 62.07- ± 39.76 mg QE/g dry stem weight. T. crispa crude extract and its isolated fraction significantly stimulate RAW264.7 cell viability (P ≤ 0.05) and intracellular INF-γ, IL-6, and IL-8 expressions. The results of LC-MS show that four of the active compounds detected in the T. crispa isolated fraction are cordioside, quercetin, eicosenoic acid (paullinic acid), and boldine. The results of this study obviously indicate that T. crispa has immunomodulatory effects through the stimulation of INF-γ, IL-6, and IL-8 expressions. LC-MS phytochemical analysis showed that the T. crispa fraction has cordioside, quercetin, eicosenoic acid (paullinic acid), and boldine, which may be responsible for the immunostimulator effect of T. crispa.

Vertebrate Herbivore Browsing on Neighboring Forage Species Increases the Growth and Dominance of Siberian Alder Across a Latitudinal Transect in Northern Alaska.

NASA Astrophysics Data System (ADS)

McNeill, E. M.; Ruess, R. W.

2017-12-01

Vertebrate herbivores strongly influence plant growth and architecture, biogeochemical cycling, and successional dynamics in boreal and arctic ecosystems. One of the most notable impacts of vertebrate herbivory is on the growth and spread of alder, a chemically-defended, N-fixing shrub whose distribution in the Alaskan arctic has expanded dramatically over the past 60 years. Although herbivore effects on thin-leaf alder are well described for interior Alaskan floodplains, no work has been conducted on the effects of herbivores on Siberian alder (Alnus viridis spp fruticosa), despite the increasing importance of this species to high latitude ecosystems. We characterized browsing by snowshoe hares, moose, and willow ptarmigan on dominant shrub species across topo-edaphic sequences within 5 ecoregions along a 600 km latitudinal transect extending from interior Alaska to the North Slope. Ptarmigan browsed wind-blown lowland and alpine sites devoid of trees in all regions; moose browsed predominantly willow species in hardwood and mixed forests and were absent north of the Brooks Range; snowshoe hares selected habitats and forage based on their local density and vulnerability to predators. Browsing intensity on Siberian alder was either undetectable or low, limited primarily to hare browsing on young ramets in the northern boreal forest where hare density relative to forage availability is highest. Overall, alder height growth was positively correlated with levels of herbivory on competing shrub species. Our data support the hypothesis that vertebrate herbivore browsing is indirectly augmenting the growth, dominance, and possible spread of Siberian alder throughout its northern Alaskan range. Given the potential high rates of N-fixation inputs by Siberian alder, we believe herbivores are also having strong indirect effects on biogeochemical cycling and possibly C storage in these landscapes.

Immunomodulatory effect of an isolated fraction from Tinospora crispa on intracellular expression of INF-γ, IL-6 and IL-8

PubMed Central

2014-01-01

Background Immunomodulators are substances that modify immune system response to a threat. Immunomodulators modulate and potentiate the immune system, keeping it highly prepared for any threat. The immunomodulatory effect of the traditional medicine Tinospora crispa is investigated in this work. Methods T. crispa ethanol extract was fractionated by using different solvents. The ethanol extract and effective isolated fraction were used to investigate the potential immunomodulatory effect of different T. crispa doses ranging from 25 μg/mL to 1000 μg/mL on RAW 246.7 cells by detecting intracellular INF-γ, IL-6, and IL-8 expressions. The antioxidant activity of T. crispa was evaluated through FRAP and DPPH. The total phenolic and total flavonoid contents were also quantified. Results Results show that T. crispa extract has higher antioxidant potential than ascorbic acid. The FRAP value of T. crispa extract is 11011.11 ± 1145.42 μmol Fe+2/g, and its DPPH inhibition percentage is 55.79 ± 7.9, with 22 μg/mL IC50. The results also reveal that the total phenolic content of T. crispa extract is 213.16- ± 1.31 mg GAE/g dry stem weight, and the total flavonoid content is 62.07- ± 39.76 mg QE/g dry stem weight. T. crispa crude extract and its isolated fraction significantly stimulate RAW264.7 cell viability (P ≤ 0.05) and intracellular INF-γ, IL-6, and IL-8 expressions. The results of LC-MS show that four of the active compounds detected in the T. crispa isolated fraction are cordioside, quercetin, eicosenoic acid (paullinic acid), and boldine. Conclusions The results of this study obviously indicate that T. crispa has immunomodulatory effects through the stimulation of INF-γ, IL-6, and IL-8 expressions. LC-MS phytochemical analysis showed that the T. crispa fraction has cordioside, quercetin, eicosenoic acid (paullinic acid), and boldine, which may be responsible for the immunostimulator effect of T. crispa. PMID:24969238

An Ecological Land Survey for Fort Wainwright, Alaska,

DTIC Science & Technology

1999-09-01

Nutt. DRYOPTERIS FRAGRANS (L.) Schott ALNUS VIRIDIS Villar ssp. CRISPA (Aiton) A. Loeve & D. Loeve GYMNOCARPIUM DRYOPTERIS (L.) Newman BETULA...OCTOPETALA POLYGONUM AMYHIBIUM L. FRAGARIA VIRGINIANA Duchesne POLYGONUM AVICULARE L. GEUM PERINCISUM Rydb. POLYGONUM CONVOLVULUS L. PENTAPHYLLOIDES

Dendrochronology and lakes: using tree-rings of alder to reconstruct lake levels

NASA Astrophysics Data System (ADS)

van der Maaten, Ernst; Buras, Allan; Scharnweber, Tobias; Simard, Sonia; Kaiser, Knut; Lorenz, Sebastian; van der Maaten-Theunissen, Marieke; Wilmking, Martin

2014-05-01

Climate change is considered a major threat for ecosystems around the world. Assessing its effects is challenging, amongst others, as we are unsure how ecosystems may respond to climate conditions they were not exposed to before. However, increased insight may be obtained by analyzing responses of ecosystems to past climate variability. In this respect, lake ecosystems appear as valuable sentinels, because they provide direct and indirect indicators of change through effects of climate. Lake-level fluctuations of closed catchments, for example, reflect a dynamic water balance, provide detailed insight in past moisture variations, and thereby allow for assessments of effects of anticipated climate change. Up to now, lake-level data are mostly obtained from gauging records and reconstructions from sediments and landforms. However, these records are in many cases only available over relatively short time periods, and, since geoscientific work is highly demanding, lake-level reconstructions are lacking for many regions. Here, we present and discuss an alternative method to reconstruct lake levels, which is based on tree-ring data of black alder (Alnus glutinosa L.). This tree species tolerates permanently waterlogged and temporally flooded conditions (i.e. riparian vegetation), and is often found along lakeshores. As the yearly growth of trees varies depending upon the experienced environmental conditions, annual rings of black alder from lakeshore vegetation likely capture information on variations in water table, and may therefore be used to reconstruct lake levels. Although alder is a relatively short-lived tree species, the frequent use of its' decay-resistant wood in foundations of historical buildings offers the possibility of extending living tree-chronologies back in time for several centuries. In this study, the potential to reconstruct lake-level fluctuations from tree-ring chronologies of black alder is explored for three lake ecosystems in the Mecklenburg

Role of river flow and sediment mobilization in riparian alder establishment along a bedrock-gravel river, South Fork Eel River, California

NASA Astrophysics Data System (ADS)

Jablkowski, P.; Johnson, E. A.; Martin, Y. E.

2017-10-01

Climatic, hydraulics, hydrologic, and fluvial geomorphic processes are the main drivers of riparian white alder (Alnus rhombifolia Nutt.) distribution in northern California. The Mediterranean climate and canyon bound, bedrock-gravel morphology of the South Fork Eel have a distinct effect on these processes. White alder seeds are preferentially deposited on river bars where river hydraulics create eddies coinciding with the downstream part of riffles and the upstream part of pools. Seeds are generally deposited below bankfull elevations by the descending hydrograph during the spring season in this Mediterranean climate. For successful germination and establishment, the seeds must be deposited at a location such that they are not remobilized by late spring flows. The summer establishment period is defined from the date of seed deposition and germination to the fall/winter date of river sediment mobilization. Seedling root growth rate decreases exponentially with decreasing water potential. However, seedlings are shown not to be generally limited by water availability at the elevations they are most commonly deposited. The establishment of white alder seedlings following the first summer will therefore depend on their ability to resist fall/winter high flows. The method proposed here compares the predicted rooting depth to predicted sediment scour rates. The length of the establishment period rather than water availability determines final seedling rooting depth. Over the past 40 years, very few years had establishment periods that were long enough or had fast enough alder growth rates to survive winter floods that often scour deeper than the total root length. The low survival of seedlings in the first autumn season following germination is believed to be a principal reason for the missing age classes often found in alder distributions along rivers.

Distribution and severity of alder phytophthora in Alaska

Treesearch

G.C. Adams; M. Catal; L. Trummer

2010-01-01

In Alaska, an unprecedented dieback and mortality of Alnus incana ssp. tenuifolia has occurred which stimulated an effort to determine causal agents of the disease. In Europe, similar dieback and mortality of Alnus incana and Alnus glutinosa has been attributed to root rot by a spectrum...

Ecotoxicity effects triggered in aquatic organisms by invasive Acer negundo and native Alnus glutinosa leaf leachates obtained in the process of aerobic decomposition.

PubMed

Manusadžianas, Levonas; Darginavičienė, Jūratė; Gylytė, Brigita; Jurkonienė, Sigita; Krevš, Alina; Kučinskienė, Alė; Mačkinaitė, Rimutė; Pakalnis, Romas; Sadauskas, Kazys; Sendžikaitė, Jūratė; Vitkus, Rimantas

2014-10-15

The replacement of autochthonous tree species by invasive ones in coastal zones of freshwater bodies induces additional alteration of hydrochemical and microbiological characteristics due to decomposition of fallen leaves of non-indigenous species, which can lead to ecotoxic response of the littoral biota. Leaves of invasive to Lithuania boxelder maple (Acer negundo) and autochthonous black alder (Alnus glutinosa) lost more than half of biomass and released stable amount of DOC (60-70 mg/L) throughout 90-day mesocosm experiment under aerobic conditions. This, along with the relatively small BOD7 values detected after some variation within the first month confirms effective biodegradation by fungi and bacteria. The ambient water was more enriched with different forms of N and P by decomposing boxelder maple than by alder leaves. During the first month, both leachates were more toxic to charophyte (Nitellopsis obtusa) at mortality and membrane depolarization levels, while later to two crustacean species. Biomarker response, H(+)-ATPase activity in membrane preparations from N. obtusa, was stronger for A. negundo. Generally, boxelder maple leaf leachates were more toxic to tested hydrobionts and this coincides with previous study on leaves of the same pair of tree species conducted under microaerobic conditions (Krevš et al., 2013). Copyright © 2014 Elsevier B.V. All rights reserved.

Community type classification of forest vegetation in young, mixed stands, interior Alaska.

Treesearch

Andrew Youngblood

1993-01-01

A total of 53 upland mixed communities were sampled and classified into five community types: Populus tremuloides/Arctostaphylos uva-ursi, Populus tremuloides/Shepherdla canadensis, Betula papyrifera-Populus tremuloides/Viburnum edule, Betula papyrifera-Populus tremuloldes/Alnus crispa and Picea glauca-Betula papyrlfera/Hylocomlum splendens. Community types were...

Unusual algal turfs associated with the rhodophyta Phyllophora crispa: Benthic assemblages along a depth gradient in the Central Mediterranean Sea

NASA Astrophysics Data System (ADS)

Bonifazi, Andrea; Ventura, Daniele; Gravina, Maria Flavia; Lasinio, Giovanna Jona; Belluscio, Andrea; Ardizzone, Gian Domenico

2017-02-01

Macroalgal assemblages dominated by the turf-forming alga Phyllophora crispa are described in detail for the first time in the Central Mediterranean Sea. This particular form of algal growth, which comprises an upper mixed layer of multiple algal species with a basal stratum formed by entangled thalli of P. crispa, was observed for the first time in 2012 along the promontory of Punta del Lazzaretto (Giglio Island, Italy). In this study, this assemblage was analysed to document the diversity of macroalgae and invertebrate associated communities and assess their distribution along a depth gradient. The algae forming turfs grow directly on the rock at low depth up to 10-15 m depth, while they grow above P. crispa from 15 m to 35 m depth, resulting in luxuriant beds covering up to 100% of the substrate. Multivariate analysis revealed clear differences regarding algae and invertebrate species richness and abundance between shallow and deep strata because of the dominance of Phyllophora crispa at depths greater than 20 m. The long laminal thalli of P. crispa favoured sessile fauna colonization, while the vagile species were principally linked to the architectural complexity of the turf layer created by the P. crispa, which increased the microhabitat diversity and favoured sediment deposition within the turf layer. The complex structures of these turf assemblages and their widespread distribution along the whole coast of the island suggest a well-established condition of the communities linked to the high natural sedimentation rate observed in the area.

Hypocholesterolemic Effects of the Cauliflower Culinary-Medicinal Mushroom, Sparassis crispa (Higher Basidiomycetes), in Diet-Induced Hypercholesterolemic Rats.

PubMed

Hong, Ki Bae; Hong, Sung-Yong; Joung, Eun Young; Kim, Byung Hee; Bae, Song-Hwan; Park, Yooheon; Suh, Hyung Joo

2015-01-01

The cauliflower culinary-medicinal mushroom, Sparassis crispa, possesses various biological activities that have been widely reported to have therapeutic applications. We examined the effects of S. crispa on serum cholesterol, hepatic enzymes related to cholesterol metabolism, and fecal sterol excretion in rats fed a cholesterol-rich diet for 4 weeks. Male Sprague-Dawley rats (8 weeks old) were randomly divided into 5 groups (n = 6 mice per group): normal diet (normal control [NC]), cholesterol-rich diet (cholesterol control [CC]), cholesterol-rich diet plus S. crispa fruiting body (SC), cholesterol-rich diet plus S. crispa extract (SCE), and cholesterol-rich diet plus S. crispa residue (SCR). SCE supplementation significantly enhanced hepatic cholesterol catabolism through the upregulation of cholesterol 7α-hydroxylase (CYP7A1) messenger RNA (mRNA) expression (2.55-fold compared with that in the NC group; P < 0.05) and the downregulation of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase mRNA expression (0.57-fold compared with that in the NC group; P < 0.05). Additionally, the SCE diet resulted in the highest fecal excretion of cholesterol and bile acid in hypercholesterolemic rats. In conclusion, mRNA expression of CYP7A1 and HMG-CoA reductase were significantly modulated by the absorption of SCE samples. Also, SCE samples had a significant effect on fecal bile acid and cholesterol excretion. These results suggest that SCE samples can induce hypocholesterolic effects through cholesterol metabolism and the reduction of circulating cholesterol levels.

Hourly pattern of allergenic alder and birch pollen concentrations in the air: Spatial differentiation and the effect of meteorological conditions

NASA Astrophysics Data System (ADS)

Borycka, K.; Kasprzyk, I.

2018-06-01

In temperate climate widespread alder and birch are an important source of strong aeroallergens. The diurnal pattern of airborne pollen concentrations depends on the rhythm of pollen release from anthers as well as weather conditions, convection air currents, long-distance transport, pollen trap location and local vegetation. The aim of the study was to present a diurnal pattern of Alnus (alder) and Betula (birch) pollen concentrations in the air in a horizontal and vertical gradient and examine the weather parameters that had the greatest impact on the pattern. The study was conducted in Rzeszów City, southeast Poland over three years. Pollen grains were collected using a Hirst volumetric spore trap at three sampling points: two at 12 m the agl, and one at 1.5 m agl. Data were analysed using circular statistics and a nonlinear function. For alder, three models of hourly patterns were elaborated and the most common presented early morning minimum and early afternoon maximum. For birch, the most common model has one peak at night and a marked decrease in concentrations in early morning, although a second model has peak during early afternoon. A model with 3 peaks is much less common. These models are characteristic for warm temperate climate regions, where alders and birches are common. The diurnal patterns did not depend on the localization of traps or proximity of the pollen source, although these factors influenced the hourly concentrations, with higher values observed at roof level. Significant relationships between the hourly pollen counts and meteorological parameters were observed only for alder. Three incidents of increasing birch pollen concentrations were observed during the first two hours of precipitation and linked to a convection effect. Unstable weather conditions caused by air convection might strongly modify the circadian pattern and cause the nightly peaks concentrations. The general results are that people suffering from allergies may be exposed

A black alder plantation improves the greenhouse gas balance of a degraded moist peat grassland

NASA Astrophysics Data System (ADS)

Bereswill, Sarah; Hoffmann, Mathias; Huth, Vytas; Popova, Yulia; Zak, Dominik; Augustin, Jürgen

2017-04-01

Drained peatlands are among the strongest terrestrial sources of the greenhouse gases (GHG) CO2 and N2O. Therefore, activities of peatland revitalisation through rewetting, often combined with the implementation of peat forming vegetation, aim to restore the GHG sink function that is characteristic for pristine peatlands. Black alder (Alnus glutinosa) naturally occurs in temperate marshes and minerotrophic peatlands (= fens) and is also suitable for paludiculture, the cultivation of biomass on wet or rewetted peatlands. However, only little information exists, if a black alder plantation can reduce the climate impact of restored peatlands. Therefore, we investigated the effect of a newly established black alder plantation on the net GHG balance of a degraded fen in north-eastern Germany during a two-year study (August 2010 - August 2012). We compared the alder plantation (Awet) with an extensively used meadow (Mwet) both characterized by very moist soil conditions and a drier reference meadow (Mdry) characterized by moderately moist soil conditions. CO2, CH4 and N2O fluxes were measured monthly to bi-monthly with the manual closed chamber method. Fluxes were calculated using a modular R script and gap filled to obtain continuous daily fluxes. Awet was a net GHG sink of -4.8 t CO2-eq ha-1 yr-1, Mwet was climate neutral (-0.03 t CO2-eq ha-1 yr-1), and Mdry was a net GHG source of 15.7 t CO2-eq ha-1 yr-1. This was mainly caused by CO2 uptake at the two very moist sites and a high CO2 release at the drier reference site. In addition, Awet was a larger CO2 sink than Mwet, likely caused by an additional CO2 uptake of the alder stand. All sites were significant CH4 sources. Due to inundation following extraordinarily heavy precipitation in summer 2011 remarkable CH4emission peaks were found on all sites which accounted for up to 70 % of the cumulated two-year CH4emissions. However, overall Awet emitted significantly lesser CH4(4.9 g C m-2 yr-1). We assume that the black

New Kunitz-Type HCRG Polypeptides from the Sea Anemone Heteractis crispa

PubMed Central

Gladkikh, Irina; Monastyrnaya, Margarita; Zelepuga, Elena; Sintsova, Oksana; Tabakmakher, Valentin; Gnedenko, Oksana; Ivanov, Alexis; Hua, Kuo-Feng; Kozlovskaya, Emma

2015-01-01

Sea anemones are a rich source of Kunitz-type polypeptides that possess not only protease inhibitor activity, but also Kv channels toxicity, analgesic, antihistamine, and anti-inflammatory activities. Two Kunitz-type inhibitors belonging to a new Heteractis crispa RG (HCRG) polypeptide subfamily have been isolated from the sea anemone Heteractis crispa. The amino acid sequences of HCRG1 and HCRG2 identified using the Edman degradation method share up to 95% of their identity with the representatives of the HCGS polypeptide multigene subfamily derived from H. crispa cDNA. Polypeptides are characterized by positively charged Arg at the N-terminus as well as P1 Lys residue at their canonical binding loop, identical to those of bovine pancreatic trypsin inhibitor (BPTI). These polypeptides are shown by our current evidence to be more potent inhibitors of trypsin than the known representatives of the HCGS subfamily with P1Thr. The kinetic and thermodynamic characteristics of the intermolecular interactions between inhibitors and serine proteases were determined by the surface plasmon resonance (SPR) method. Residues functionally important for polypeptide binding to trypsin were revealed using molecular modeling methods. Furthermore, HCRG1 and HCRG2 possess anti-inflammatory activity, reducing tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6) secretions, as well as proIL-1β expression in lipopolysaccharide (LPS)-activated macrophages. However, there was no effect on nitric oxide (NO) generation. PMID:26404319

Properties and potential applications of the culinary-medicinal cauliflower mushroom, Sparassis crispa Wulf.:Fr. (Aphyllophoromycetideae): a review.

PubMed

Chandrasekaran, Gayathri; Oh, Deuk-Sil; Shin, Hyun-Jae

2011-01-01

Sparassis crispa is a culinary-medicinal mushroom that has recently become popular in Korea, China, Japan, Germany, and the USA. S. crispa is a good source of food and nutraceuticals, or dietary supplements, due to its rich flavor compounds and beta-glucan content. This review is a comprehensive summary of its distribution, growth, management, general constituents, functional ingredients, as well as its current and potential medicinal and other applications.

Red alder potential in Alaska

Treesearch

Allen Brackley; David Nicholls; Mike Hannan

2010-01-01

Over the past several decades, red alder has established itself as a commercially important species in the Pacific Northwest. Once considered a weed species, red alder now commands respect within many markets, including furniture, architectural millwork, and other secondary manufactured products. Although red alder's natural range extends to southeast Alaska, an...

Red alder stand development and dynamics.

Treesearch

R.L. Deal

2006-01-01

This paper synthesizes information on the development of natural pure red alder stands and dynamics of mixed alder-conifer stands. Early research on red alder growth and yield focused on developing stand volume and normal yield. tables for alder in the Pacific Northwest. Recent site-index estimation and height-growth curves were developed on a 20-year site base age....

Hardwood price reporting.

Treesearch

Brent L. Sohngen; Richard W. Haynes

1994-01-01

Prices for red alder (Alnus rubra Bong.) hardwood logs are published and analyzed for reliability, consistency, and robustness. Timberland managers can use these prices to make decisions about land management. They show that values for red alder logs have been increasing steadily for the last 11 years.

Edge-glued panels from Alaska hardwoods: retail manager perspectives

Treesearch

David Nicholls; Matthew Bumgardner; Valerie Barber

2010-01-01

In Alaska, red alder (Alnus rubra Bong.) and paper birch (Betula papyrifera Marsh.) are both lesser-known hardwoods grown, harvested, and manufactured into appearance products, with potential for increased utilization. The production of edgeglued panels from red alder and paper birch offers one expansion opportunity for wood...

Utilization and management of alder.

Treesearch

David G. Briggs; Dean S. DeBell; William A. Atkinson

1978-01-01

In the Pacific Northwest and British Columbia, red alder often grows on forest lands following natural or man-caused disturbances. Frequently ignored as a pest or weed, many alder stands have developed to the point where important utilization and management questions are being asked. It is recognized that alder is a fast growing species, and that its rapid early growth...

Managing young upland forests in southeast Alaska for wood products, wildlife, aquatic resources, and fishes: problem analysis and study plan.

Treesearch

Mark S. Wipfli; Robert L. Deal; Paul E. Hennon; Adelaide C. Johnson; Toni L. de Santo; Thomas A. Hanley; Mark E. Schultz; Mason D. Bryant; Richard T. Edwards; Ewa H. Orlikowska; Takashi Gomi

2002-01-01

Red alder (Alnus rubra Bong.) appears to influence the productivity of young-growth conifer forests and affect the major resources (timber, wildlife, and fisheries) of forested ecosystems in southeast Alaska. We propose an integrated approach to understanding how alder influences trophic links and processes in young-growth ecosystems. The presence...

Safety, Efficacy, and Physicochemical Characterization of Tinospora crispa Ointment: A Community-Based Formulation against Pediculus humanus capitis

PubMed Central

Torre, Gerwin Louis Tapan Dela; Ponsaran, Kerstin Mariae Gonzales; de Guzman, Angelica Louise Dela Peña; Manalo, Richelle Ann Mallapre; Arollado, Erna Custodio

2017-01-01

The high prevalence of pediculosis capitis, commonly known as head lice (Pediculus humanus capitis) infestation, has led to the preparation of a community-based pediculicidal ointment, which is made of common household items and the extract of Tinospora crispa stem. The present study aimed to evaluate the safety, efficacy, and physicochemical characteristics of the T. crispa pediculicidal ointment. The physicochemical properties of the ointment were characterized, and safety was determined using acute dermal irritation test (OECD 404), while the efficacy was assessed using an in vitro pediculicidal assay. Furthermore, the chemical compounds present in T. crispa were identified using liquid-liquid extraction followed by ultra-performance liquid chromatography quadruple time-of-flight mass spectrometric (UPLC-qTOF/MS) analysis. The community-based ointment formulation was light yellow in color, homogeneous, smooth, with distinct aromatic odor and pH of 6.92±0.09. It has spreadability value of 15.04±0.98 g·cm/sec and has thixotropic behavior. It was also found to be non-irritant, with a primary irritation index value of 0.15. Moreover, it was comparable to the pediculicidal activity of the positive control Kwell®, a commercially available 1% permethrin shampoo (P>0.05), and was significantly different to the activity of the negative control ointment, a mixture of palm oil and candle wax (P<0.05). These findings suggested that the community-based T. crispa pediculicidal ointment is safe and effective, having acceptable physicochemical characteristics. Its activity can be attributed to the presence of compounds moupinamide and physalin I. PMID:28877572

Red alder: a state of knowledge.

Treesearch

Robert L. Deal; Constance A. Harrington

2006-01-01

In March 23-25, 2005, an international symposium on red alder was held at the University of Washington Center for Urban Horticulture in Seattle, WA. The symposium was entitled "Red alder: A State of Knowledge" and brought together regional experts to critically examine the economic, ecological and social values of red alder. The primary goal of the symposium...

Microwave-based reaction screening: tandem retro-Diels-Alder/Diels-Alder cycloadditions of o-quinol dimers.

PubMed

Dong, Suwei; Cahill, Katharine J; Kang, Moon-Il; Colburn, Nancy H; Henrich, Curtis J; Wilson, Jennifer A; Beutler, John A; Johnson, Richard P; Porco, John A

2011-11-04

We have accomplished a parallel screen of cycloaddition partners for o-quinols utilizing a plate-based microwave system. Microwave irradiation improves the efficiency of retro-Diels-Alder/Diels-Alder cascades of o-quinol dimers which generally proceed in a diastereoselective fashion. Computational studies indicate that asynchronous transition states are favored in Diels-Alder cycloadditions of o-quinols. Subsequent biological evaluation of a collection of cycloadducts has identified an inhibitor of activator protein-1 (AP-1), an oncogenic transcription factor.

Maintaining cultures of wood-rotting fungi.

Treesearch

E.E. Nelson; H.A. Fay

1985-01-01

Phellinus weirii cultures were stored successfully for 10 years in small alder (Alnus rubra Bong.) disks at 2 °C. The six isolates tested appeared morphologically identical and after 10 years varied little in growth rate from those stored on malt agar slants. Long-term storage on alder disks reduces the time required for...

Microwave-Based Reaction Screening: Tandem Retro-Diels-Alder/Diels-Alder Cycloadditions of ortho-Quinol Dimers

PubMed Central

Dong, Suwei; Cahill, Kath arine J.; Kang, Moon -Il; Colburn, Nancy H.; Henrich, Curtis J.; Wilson, Jennifer A.; Beutler, John A.; Johnson, Richard P.; Porco, John A.

2011-01-01

We have accomplished a parallel screen of cycloaddition partners for ortho-quinols utilizing a plate-based microwave system. Microwave irradiation improves the efficiency of retro-Diels-Alder/Diels-Alder cascades of ortho-quinol dimers which generally proceed in a diastereoselective fashion. Computational studies indicate that asynchronous transition states are favored in Diels-Alder cycloadditions of ortho-quinols. Subsequent biological evaluation of a collection of cycloadducts has identified an inhibitor of activator protein-1 (AP-1), an oncogenic transcription factor. PMID:21942286

Control of red alder by cutting.

Treesearch

Dean S. DeBell; Thomas C. Turpin

1989-01-01

Effects of tree age, month of cut, and height and angle of cut on sprouting of red alder stumps were evaluated in a study designed to develop an effective method for controlling red alder in Douglas-fir plantations. Ninety-five percent or more of alder stumps cut in June or July died by the end of the next growing season; mortality was 88, 70, and 22 percent for stumps...

Effect of Alnus glutinosa on hybrid populus growth and soil nitrogen concentration in a mixed plantation

Treesearch

Jeffrey O. Dawson; Edward A. Hansen

1983-01-01

Height growth of hybrid Populusand soil nitrogen concentration around Alnus glutinosa stems differed significantly both spatially and with the Alnus/Populus mixture in a short-rotation intensively cultured mixed planting. Populus height growth comparable to that obtained from optimal rates of...

Origins of Stereoselectivity in the trans-Diels-Alder Paradigm

PubMed Central

Paton, Robert S.; Mackey, Joel L.; Kim, Woo Han; Lee, Jun Hee; Danishefsky, Samuel J.; Houk, K. N.

2010-01-01

The regioselectivity and stereoselectivity aspects of the Diels-Alder/radical hydrodenitration reaction sequence leading to trans-fused ring systems have been investigated with density functional calculations. A continuum of transition structures representing Diels-Alder and hetero-Diels-Alder cycloadditions as well as a sigmatropic rearrangement have been located, and they all lie very close in energy on the potential energy surface. All three pathways are found to be important in the formation of the Diels-Alder adduct. Reported regioselectivities are reproduced by the calculations. The stereoselectivity of radical hydrodenitration of the cis-Diels-Alder adduct is found to be related to the relative conformational stabilities of bicyclic radical intermediates. Overall, the computations provide understanding of the regioselectivities and stereoselectivities of the trans-Diels-Alder paradigm. PMID:20557046

Effects of Alder Mine on the Water, Sediments, and Benthic Macroinvertebrates of Alder Creek, 1998 Annual Report.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peplow, Dan

1999-05-28

The Alder Mine, an abandoned gold, silver, copper, and zinc mine in Okanogan County, Washington, produces heavy metal-laden effluent that affects the quality of water in a tributary of the Methow River. The annual mass loading of heavy metals from two audits at the Alder Mine was estimated to exceed 11,000 kg per year. In this study, water samples from stations along Alder Creek were assayed for heavy metals by ICP-AES and were found to exceed Washington State's acute freshwater criteria for cadmium (Cd), copper (Cu), selenium (Se), and zinc (Zn).

Promotion of adventitious root formation of difficult-to-root hardwood tree species

Treesearch

Paula M. Pijut; Keith E. Woeste; Charles H. Michler

2011-01-01

North American hardwood tree species, such as alder (Alnus spp.), ash (Fraxinus spp.), basswood (Tilia spp.), beech (Fagus spp.), birch (Betula spp.), black cherry (Prunus seratina), black walnut (Juglans nigra), black willow (...

Volume tables for red alder.

Treesearch

Floyd A. Johnson; R. M. Kallander; Paul G. Lauterbach

1949-01-01

The increasing importance of red alder as a commercial species in the Pacific Northwest has prompted the three agencies listed above to pool their tree measurement data for the construction of standard regional red alder volume tables. The tables included here were based on trees from a variety of sites and form classes. Approximately one quarter of the total number of...

Succession on regraded placer mine spoil in Alaska, USA, in relation to initial site characteristics

USGS Publications Warehouse

Densmore, R.V.

1994-01-01

This study evaluated the rate and pattern of natural succession on regraded placer mine spoil in relation to initial substrate characteristics. The study site was the Glen Creek watershed of the Kantishna mining area of Denali National Park and Preserve, Alaska. After regrading, twelve 0.01-ha plots were established and substrate characteristics were measured. Natural plant succession was evaluated after five growing seasons. Three successional patterns were identified on the basis of plant community characteristics using cluster analysis, and were related to substrate characteristics. First, a riparian plant community with vigorous Salix alaxensis and Alnus crispa grew rapidly on topsoil that had been spread over the regraded spoil. Second, a similar plant community with less vigorous S. alaxensis developed more slowly on unprocessed spoil and spoil amended with a small amount of topsoil. Third, processed spoil remained almost bare of vegetation, although S. alaxensis was able to establish and persist in a stunted growth form. In contrast, Alnus crispa had difficulty establishing on processed spoil, but the few established seedlings grew well. Several substrate variables, including the proportion of silt and clay vs. sand, total nitrogen, and water retention capacity, were good predictors of the rate and pattern of succession. Total nitrogen was the best single predictor for the number of vigorous S. alaxensis.

Spatiotemporal models for predicting high pollen concentration level of Corylus, Alnus, and Betula.

PubMed

Nowosad, Jakub

2016-06-01

Corylus, Alnus, and Betula trees are among the most important sources of allergic pollen in the temperate zone of the Northern Hemisphere and have a large impact on the quality of life and productivity of allergy sufferers. Therefore, it is important to predict high pollen concentrations, both in time and space. The aim of this study was to create and evaluate spatiotemporal models for predicting high Corylus, Alnus, and Betula pollen concentration levels, based on gridded meteorological data. Aerobiological monitoring was carried out in 11 cities in Poland and gathered, depending on the site, between 2 and 16 years of measurements. According to the first allergy symptoms during exposure, a high pollen count level was established for each taxon. An optimizing probability threshold technique was used for mitigation of the problem of imbalance in the pollen concentration levels. For each taxon, the model was built using a random forest method. The study revealed the possibility of moderately reliable prediction of Corylus and highly reliable prediction of Alnus and Betula high pollen concentration levels, using preprocessed gridded meteorological data. Cumulative growing degree days and potential evaporation proved to be two of the most important predictor variables in the models. The final models predicted not only for single locations but also for continuous areas. Furthermore, the proposed modeling framework could be used to predict high pollen concentrations of Corylus, Alnus, Betula, and other taxa, and in other countries.

Spatiotemporal models for predicting high pollen concentration level of Corylus, Alnus, and Betula

NASA Astrophysics Data System (ADS)

Nowosad, Jakub

2016-06-01

Corylus, Alnus, and Betula trees are among the most important sources of allergic pollen in the temperate zone of the Northern Hemisphere and have a large impact on the quality of life and productivity of allergy sufferers. Therefore, it is important to predict high pollen concentrations, both in time and space. The aim of this study was to create and evaluate spatiotemporal models for predicting high Corylus, Alnus, and Betula pollen concentration levels, based on gridded meteorological data. Aerobiological monitoring was carried out in 11 cities in Poland and gathered, depending on the site, between 2 and 16 years of measurements. According to the first allergy symptoms during exposure, a high pollen count level was established for each taxon. An optimizing probability threshold technique was used for mitigation of the problem of imbalance in the pollen concentration levels. For each taxon, the model was built using a random forest method. The study revealed the possibility of moderately reliable prediction of Corylus and highly reliable prediction of Alnus and Betula high pollen concentration levels, using preprocessed gridded meteorological data. Cumulative growing degree days and potential evaporation proved to be two of the most important predictor variables in the models. The final models predicted not only for single locations but also for continuous areas. Furthermore, the proposed modeling framework could be used to predict high pollen concentrations of Corylus, Alnus, Betula, and other taxa, and in other countries.

Heterogeneous Diels–Alder catalysis for biomass-derived aromatic compounds

DOE PAGES

Settle, Amy E.; Berstis, Laura; Rorrer, Nicholas A.; ...

2017-05-17

In this tutorial review, we provide an overview of heterogeneous Diels–Alder catalysis for the production of lignocellulosic biomass-derived aromatic compounds. Diels–Alder reactions afford an extremely selective and efficient route for carbon–carbon cycloadditions to produce intermediates that can readily undergo subsequent dehydration or dehydrogenation reactions for aromatization. As a result, catalysis of Diels–Alder reactions with biomass-derived dienes and dienophiles has seen a growth of interest in recent years; however, significant opportunities remain to (i) tailor heterogeneous catalyst materials for tandem Diels–Alder and aromatization reactions, and (ii) utilize biomass-derived dienes and dienophiles to access both conventional and novel aromatic monomers. As such,more » this review discusses the mechanistic aspects of Diels–Alder reactions from both an experimental and computational perspective, as well as the synergy of Brønsted–Lewis acid catalysts to facilitate tandem Diels–Alder and aromatization reactions. Heterogeneous catalyst design strategies for Diels–Alder reactions are reviewed for two exemplary solid acid catalysts, zeolites and polyoxometalates, and recent efforts for targeting direct replacement aromatic monomers from biomass are summarized. In conclusion, we point out important research directions for progressing Diels–Alder catalysis to target novel, aromatic monomers with chemical functionality that enables new properties compared to monomers that are readily accessible from petroleum.« less

Oral administration of soluble β-glucan preparation from the cauliflower mushroom, Sparassis crispa (Higher Basidiomycetes) modulated cytokine production in mice.

PubMed

Hida, Toshie H; Kawaminami, Hiromi; Ishibashi, Ken-Ichi; Miura, Noriko N; Adachi, Yoshiyuki; Ohno, Naohito

2013-01-01

Soluble β-glucan preparation from the cold NaOH extract of Sparassis crispa (SCG) is a six-branched 1,3-β-D-glucan that is a major cell-wall structural component in fungi. Leukocytes from DBA/2 mice are highly sensitive to SCG, producing cytokines in vitro. We previously reported that the intraperitoneal (i.p.) administration of β-glucan decreased cytokine induction by SCG in vitro in DBA/2 mice. In this study, we examined the effects of the oral (p.o.) administration of polysaccharide fractions extracted from S. crispa, using hot water (SCHWE), a β-glucan from S. crispa, to DBA/2 mice on cytokine induction by SCG in the spleen in vitro. The level of induction of IFN-γ and GM-CSF by SCG was significantly increased in SCHWE-treated mice. This activity was more clearly observed when chlorpromazine was administered as a pretreatment in SCHWE-treated mice. The production of GM-CSF, IFN-γ, and IL-6 by immune cells in Peyer's patches was higher in SCHWE-treated mice than in control mice. These results suggest that orally administered β-glucan may modulate cytokine induction by SCG in the spleen through the activation of Peyer's patches.

Bioactive Pentacyclic Triterpene Ester Derivatives from Alnus viridis ssp. viridis Bark.

PubMed

Novakovic, Miroslav; Nikodinovic-Runic, Jasmina; Veselinovic, Jovana; Ilic-Tomic, Tatjana; Vidakovic, Vera; Tesevic, Vele; Milosavljevic, Slobodan

2017-05-26

Seven derivatives of pentacyclic triterpene acids (1-7) were isolated from the bark of Alnus viridis ssp. viridis using a combination of column chromatography and semipreparative HPLC. Compounds 1-3, 6, and 7 were determined to be new after spectroscopic data interpretation and were assigned as 27-hydroxyalphitolic acid derivatives (1-3), a 27-hydroxybetulinic acid derivative (6), and a 3-epi-maslinic acid derivative (7), respectively. Pentacyclic triterpenoids with a C-27 hydroxymethyl group have been found in species of the genus Alnus for the first time. These compounds were subjected to cytotoxicity testing against a number of cancer cell lines. Also, selected pentacyclic triterpenoids were selected as potential inhibitors of topoisomerases I and IIα for an in silico investigation.

Decay fungi of riparian trees in the Southwestern U.S.

Treesearch

Jessie A. Glaeser; Kevin T. Smith

2013-01-01

Most of the tree species that characterize riparian woodlands are early or facultative seral species including Fremont cottonwood (Populus fremontii), Arizona alder (Alnus oblongifolia), Arizona sycamore (Platanus wrightii), Modesto ash (Fraxinus velutina), boxelder (Acer negundo...

Predicting crown weight and bole volume of five Western hardwoods.

Treesearch

J.A. Kendall Snell; Susan N. Little

1983-01-01

Regression equations are presented for estimating biomass of five western hardwoods: red alder (Alnus rubra Bong.), giant chinkapin (Castanopsis chrysophylla (Dougl.) A. DC.), bigleaf maple (Acer macrophyllum Pursh), Pacific madrone (Arbutus menziesii Pursh), and tanoak (...

Alder flycatcher

Treesearch

Scott H. Stoleson

2010-01-01

The alder flycatcher is a small flycatcher in the confusing genus Empidonax. It so closely resembles its look-alike congener, the willow flycatcher (E. traillii), that until 1973 they were considered a single species, Traill's flycatcher (American Ornithologists' Union 1973). As most published studies of Traill's...

In vitro asymbiotic germination for micropropagation of the recalcitrant terrestrial orchid Chloraea crispa (Orchidaceae).

PubMed

Quiroz, Karla; Saavedra, Jessica; Vogel, Hermine; Verdugo, Gabriela; Caligari, Peter D S; García-Gonzáles, Rolando

2017-08-01

Chloraea crispa is a terrestrial Orchidaceae species native to Chile, characterized by a beautiful and showy inflorescence. The species has a great potential for commercial exploitation in the cut flower industry, but it is essential to improve propagation methods to avoid endangering its natural populations. Because this species is hard to propagate using traditional greenhouse techniques, in vitro techniques offer an effective tool for its large-scale production in terms of germination, growth, and propagation. The current study evaluated the effect of the culture medium on the asymbiotic germination of C. crispa seeds, as well as the effects of the plant growth regulators 6-benzylaminopurine and indole-3-butyric acid. Different light regimes were also studied. A significant effect was observed for the interaction between culture media and light regime on the morphogenic response of the seeds. The highest rate of embryonic germination was obtained in Van Waes medium supplemented with 0.1 mg·L -1 of 6-benzylaminopurine. For the first time, asymbiotic culture of this species using biotechnology tools has been developed. Plantlets developed very well under in vitro conditions, allowing the possibility to propagate and store genetic material for conservation and domestication purposes.

Root-associated ectomycorrhizal fungi shared by various boreal forest seedlings naturally regenerating after a fire in interior alaska and correlation of different fungi with host growth responses.

PubMed

Bent, Elizabeth; Kiekel, Preston; Brenton, Rebecca; Taylor, D Lee

2011-05-01

The role of common mycorrhizal networks (CMNs) in postfire boreal forest successional trajectories is unknown. We investigated this issue by sampling a 50-m by 40-m area of naturally regenerating black spruce (Picea mariana), trembling aspen (Populus tremuloides), and paper birch (Betula papyrifera) seedlings at various distances from alder (Alnus viridis subsp. crispa), a nitrogen-fixing shrub, 5 years after wildfire in an Alaskan interior boreal forest. Shoot biomasses and stem diameters of 4-year-old seedlings were recorded, and the fungal community associated with ectomycorrhizal (ECM) root tips from each seedling was profiled using molecular techniques. We found distinct assemblages of fungi associated with alder compared with those associated with the other tree species, making the formation of CMNs between them unlikely. However, among the spruce, aspen, and birch seedlings, there were many shared fungi (including members of the Pezoloma ericae [Hymenoscyphus ericae] species aggregate, Thelephora terrestris, and Russula spp.), raising the possibility that these regenerating seedlings may form interspecies CMNs. Distance between samples did not influence how similar ECM root tip-associated fungal communities were, and of the fungal groups identified, only one of them was more likely to be shared between seedlings that were closer together, suggesting that the majority of fungi surveyed did not have a clumped distribution across the small scale of this study. The presence of some fungal ribotypes was associated with larger or smaller seedlings, suggesting that these fungi may play a role in the promotion or inhibition of seedling growth. The fungal ribotypes associated with larger seedlings were different between spruce, aspen, and birch, suggesting differential impacts of some host-fungus combinations. One may speculate that wildfire-induced shifts in a given soil fungal community could result in variation in the growth response of different plant species

Linking landscape characteristics and stream nitrogen in the Oregon Coast Range: Empirical modeling of water quality monitoring data

EPA Science Inventory

Background sources of nitrogen (N) provide a challenge for setting stream nutrient criteria in the Pacific Northwest US. Red alder (Alnus rubra), an early successional nitrogen fixing tree, and sea salt inputs can strongly influence stream N concentrations observed in individual...

Volume and taper tables for red alder.

Treesearch

Robert O. Curtis; David Bruce; Caryanne VanCoevering

1968-01-01

Red alder is a species of increasing importance in the Pacific Northwest. Interest in improved volume tables for the species resulted in publication of the 1949 volume tables. More recently, Browne (1962) published cubic-foot-volume tables for red alder in British Columbia, and Hoyer (1966) presented tarif access tables, based on the 1949 tables, for use with the...

The impact of a pulsing groundwater table on greenhouse gas emissions in riparian grey alder stands.

PubMed

Mander, Ülo; Maddison, Martin; Soosaar, Kaido; Teemusk, Alar; Kanal, Arno; Uri, Veiko; Truu, Jaak

2015-02-01

Floods control greenhouse gas (GHG) emissions in floodplains; however, there is a lack of data on the impact of short-term events on emissions. We studied the short-term effect of changing groundwater (GW) depth on the emission of (GHG) carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) in two riparian grey alder (Alnus incana) stands of different age in Kambja, southern Estonia, using the opaque static chamber (five replicates in each site) and gas chromatography methods. The average carbon and total nitrogen content in the soil of the old alder (OA) stand was significantly higher than in the young alder (YA) stand. In both stands, one part was chosen for water table manipulation (Manip) and another remained unchanged with a stable and deeper GW table. Groundwater table manipulation (flooding) significantly increases CH4 emission (average: YA-Dry 468, YA-Manip 8,374, OA-Dry 468, OA-Manip 4,187 μg C m(-2) h(-1)) and decreases both CO2 (average: OA-Dry 138, OA-Manip 80 mg C m(-2) h(-1)) and N2O emissions (average: OA-Dry 23.1, OA-Manip 11.8 μg N m(-2) h(-1)) in OA sites. There was no significant difference in CO2 and CH4 emissions between the OA and YA sites, whereas in OA sites with higher N concentration in the soil, the N2O emission was significantly higher than at the YA sites. The relative CO2 and CH4 emissions (the soil C stock-related share of gaseous losses) were higher in manipulated plots showing the highest values in the YA-Manip plot (0.03 and 0.0030 % C day(-1), respectively). The soil N stock-related N2O emission was very low achieving 0.000019 % N day(-1) in the OA-Dry plot. Methane emission shows a negative correlation with GW, whereas the 20 cm depth is a significant limit below which most of the produced CH4 is oxidized. In terms of CO2 and N2O, the deeper GW table significantly increases emission. In riparian zones of headwater streams, the short-term floods (e.g. those driven by extreme climate events) may significantly enhance

A facile microwave-assisted Diels-Alder reaction of vinylboronates.

PubMed

Sarotti, Ariel M; Pisano, Pablo L; Pellegrinet, Silvina C

2010-11-21

The Diels-Alder reaction of vinylboronates can be easily performed using microwave irradiation giving excellent yields of the cycloadducts. Pinacol vinylboronate was the reagent of choice due to its stability towards hydrolysis, operational simplicity and yields of Diels-Alder products. To the best of our knowledge, this is the first example of microwave-assisted Diels-Alder reaction of boron-substituted dienophiles. Subsequent in situ oxidation of the cycloadducts with alkaline hydrogen peroxide afforded the alcohols efficiently.

Bounding salt marsh nitrogen fluxes: development of an ecohydrological salt marsh model

EPA Science Inventory

A mass-balance approach to characterize nitrogen flux in a 2-hectare, meso-haline saltmarsh yielded extensive flow and water chemistry data. However, a significant, unevenly distributed population of the nitrogen fixer Alnus rubra (red alder) in the 20-hectare upland catchment l...

Direct amplification of DNA from fresh and preserved ectomycorrhizal root tips

Treesearch

Elizabeth Bent; D. Lee Taylor

2009-01-01

Methods are described by which DNA can be amplified directly from ectomycorrhizal root tip homogenates of a variety of plant species (Picea mariana (black spruce), Betula papyrifera (paper birch), Populus tremuloides (trembling aspen) and Alnus sp.(alder)), including root tips that have...

TERRESTRIAL AND MARINE SOURCES OF NUTRIENTS TO AN OREGON COASTAL RIVER

EPA Science Inventory

In the Pacific Northwest of North America, anadromous fish can transport significant quantities of nutrients and energy from the ocean to the watersheds where they return, reproduce and die. In addition, the widespread distribution of N2-fixing alders (Alnus spp.) can influence ...

Effect on Tumor Necrosis Factor-α Production and Antioxidant Ability of Black Alder, as Factors Related to Its Anti-Inflammatory Properties

PubMed Central

Acero, Nuria

2012-01-01

Abstract Alders exhibit several uses in different areas and also offer some nutritional and medicinal values. The bark and leaves from black alder [Alnus glutinosa (L.) Gaertn] are used in folk medicine for the treatment of inflammatory processes and other health disorders. This study assessed if an extract of A. glutinosa stem bark exhibits some biological properties linked to improving the inflammatory state, which could partly justify its ethnopharmacological use. Therefore, various aspects of antioxidant activity as well as the effect on tumor necrosis factor-α (TNF-α) production were evaluated. The phytochemical study revealed the presence of terpenes, saponins, tannins, flavonoids, and anthraquinones (by high-performance thin-layer chromatography). The betulinic acid content in the extract, determined by reversed-phase high-performance liquid chromatography (validated method), was 0.72±0.027%. In addition, high amounts for total phenols as well as flavonoids were determined. The extract exhibited a 2,2′-diphenylpicrylhydrazyl radical scavenging capacity similar to that of ascorbic acid and had a significant effect on superoxide anion scavenging, superior to that of ascorbic acid. It was also able to protect HeLa cells from induced oxidative stress. In the TNF-α assay, levels of this citokine were depressed by the extract in HL-60 cells. To test the effect of the extract on cell proliferation, a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was performed. According to the results, the antioxidant properties displayed by the extract of A. glutinosa stem bark, together with the effect on TNF-α levels, suggest that these activities, linked to a successful reduction in inflammatory processes, may support, in part, its ethnopharmacological use. PMID:22424456

Spatial variation in population dynamics of Sitka mice in floodplain forests.

Treesearch

T.A. Hanley; J.C. Barnard

1999-01-01

Population dynamics and demography of the Sitka mouse, Peromyscus keeni sitkensis, were studied by mark-recapture live-trapping over a 4-year period in four floodplain and upland forest habitats: old-growth Sitka spruce (Picea sitchensis) floodplain; red alder (Alnus rubra) floodplain; beaver-pond...

From the forest to the sea and back again: Biogeochemistry in the Oregon Coast Range

EPA Science Inventory

Variations in plant community composition across the landscape can influence nutrient retention and loss at the watershed scale. A striking example of plant species influence is the role of N2-fixing red alder (Alnus rubra) in the biogeochemistry of Pacific Northwest forests. A...

Production and assessment of red alder planting stock.

Treesearch

M.A. Radwan; Y. Tanaka; A. Dobkowskl; W. Fangen

1992-01-01

A series of experiments was conducted over 4 years to test and develop methods to produce acceptable red alder planting stock and to assess quality and outplanting performance of resulting stock. Results indicated that red alder planting stock can be produced as containerized seedlings (plugs) or as bare-root nontransplant and transplant trees. In general, bare-root...

Effects of surface inactivation, high temperature drying and preservative treatment on surface roughness and colour of alder and beech wood

NASA Astrophysics Data System (ADS)

Aydin, Ismail; Colakoglu, Gursel

2005-10-01

Although extensive research has been conducted in wood surface quality analysis, a unified approach to surface quality characterisation does not exist. Measurements of the variation in surface roughness and surface colour are used widely for the evaluation of wood surface quality. Colour is a basic visual feature for wood and wood-based products. Colour measurement is one of the quality control tests that should be carried out because the colour deviations are spotted easily by the consumers. On the other hand, a common problem faced by plywood manufacturers is panel delamination, for which a major cause is poor quality glue-bonds resulting from rough veneer. Rotary cut veneers with dimensions of 500 mm × 500 mm × 2 mm manufactured from alder ( Alnus glutinosa subsp. barbata) and beech ( Fagus orientalis Lipsky) logs were used as materials in this study. Veneer sheets were oven-dried in a veneer dryer at 110 °C (normal drying temperature) and 180 °C (high drying temperature) after peeling process. The surfaces of some veneers were then exposed at indoor laboratory conditions to obtain inactive wood surfaces for glue bonds, and some veneers were treated with borax, boric acid and ammonium acetate solutions. After these treatments, surface roughness and colour measurements were made on veneer surfaces. High temperature drying process caused a darkening on the surfaces of alder and beech veneers. Total colour change value (Δ E*) increased linear with increasing exposure time. Among the treatment solutions, ammonium acetate caused the biggest colour change while treatment with borax caused the lowest changes in Δ E* values. Considerable changes in surface roughness after preservative treatment did not occur on veneer surfaces. Generally, no clear changes were obtained or the values mean roughness profile ( Ra) decreased slightly in Ra values after the natural inactivation process.

In vitro asymbiotic germination for micropropagation of the recalcitrant terrestrial orchid Chloraea crispa (Orchidaceae)1

PubMed Central

Quiroz, Karla; Saavedra, Jessica; Vogel, Hermine; Verdugo, Gabriela; Caligari, Peter D. S.; García-Gonzáles, Rolando

2017-01-01

Premise of the study: Chloraea crispa is a terrestrial Orchidaceae species native to Chile, characterized by a beautiful and showy inflorescence. The species has a great potential for commercial exploitation in the cut flower industry, but it is essential to improve propagation methods to avoid endangering its natural populations. Because this species is hard to propagate using traditional greenhouse techniques, in vitro techniques offer an effective tool for its large-scale production in terms of germination, growth, and propagation. Methods: The current study evaluated the effect of the culture medium on the asymbiotic germination of C. crispa seeds, as well as the effects of the plant growth regulators 6-benzylaminopurine and indole-3-butyric acid. Different light regimes were also studied. Results: A significant effect was observed for the interaction between culture media and light regime on the morphogenic response of the seeds. The highest rate of embryonic germination was obtained in Van Waes medium supplemented with 0.1 mg·L−1 of 6-benzylaminopurine. Discussion: For the first time, asymbiotic culture of this species using biotechnology tools has been developed. Plantlets developed very well under in vitro conditions, allowing the possibility to propagate and store genetic material for conservation and domestication purposes. PMID:28924509

Late Quaternary dynamics of forest vegetation on northern Vancouver Island, British Columbia, Canada

NASA Astrophysics Data System (ADS)

Lacourse, Terri

2005-01-01

Pollen analysis of radiocarbon-dated lake sediment from northern Vancouver Island, southwest British Columbia reveals regional changes in forest vegetation over the last 12,200 14C yr (14,900 cal yr). Between at least 12,200 and 11,700 14C yr BP (14,900-13,930 cal yr BP), open woodlands were dominated by Pinus contorta, Alnus crispa, and various ferns. As P. contorta decreased in abundance, Alnus rubra and more shade-tolerant conifers (i.e., Picea and Tsuga mertensiana) increased. Increases in T. mertensiana, P. contorta, and A. crispa pollen accumulation rates (PARs) between 10,600 and 10,400 14C yr BP (11,660-11,480 cal yr BP) reflect a cool and moist climate during the Younger Dryas chronozone. Orbitally induced warming around 10,000 14C yr BP (11,090 cal yr BP) allowed the northward extension of Pseudotsuga menziesii, although Picea, Tsuga heterophylla, and A. rubra dominated early Holocene forests. By 7500 14C yr BP (8215 cal yr BP), shade-tolerant T. heterophylla was the dominant forest tree. Cupressaceae ( Thuja plicata and Chamaecyparis nootkatensis) was present by 7500 14C yr BP but reached its maximum after 3500 14C yr BP (3600 cal yr BP), when a cooler and wetter regional climate facilitated the development of temperate rainforest. The highest rates of vegetation change are associated with Lateglacial climate change and species with rapid growth rates and short life spans.

Natural products and biological activity of the pharmacologically active cauliflower mushroom Sparassis crispa.

PubMed

Kimura, Takashi

2013-01-01

Sparassis crispa, also known as cauliflower mushroom, is an edible mushroom with medicinal properties. Its cultivation became popular in Japan about 10 years ago, a phenomenon that has been attributed not only to the quality of its taste, but also to its potential for therapeutic applications. Herein, I present a comprehensive summary of the pharmacological activities and mechanisms of action of its bioactive components, such as beta-glucan, and other physiologically active substances. In particular, the immunomodulatory mechanisms of the beta-glucan components are presented herein in detail.

Occultocarpon, a new monotypic genus of Gnomoniaceae on Alnus nepalensis from China

USDA-ARS?s Scientific Manuscript database

A new monotypic genus Occultocarpon and its species, O. ailaoshanense, was discovered on the bark of branches of Alnus nepalensis (Betulaceae) in Yunnan, China. A phylogeny based on three genes (LSU, rpb2, tef1-a) reveals that O. ailaoshanense belongs to the Gnomoniaceae (Diaporthales, Ascomycetes) ...

Ectomycorrhizal and endophytic fungi associated with Alnus glutinosa growing in a saline area of central Poland.

PubMed

Thiem, Dominika; Piernik, Agnieszka; Hrynkiewicz, Katarzyna

2018-01-01

Alnus glutinosa (black alder) is a mycorrhizal pioneer tree species with tolerance to high concentrations of salt in the soil and can therefore be considered to be an important tree for the regeneration of forests areas devastated by excessive salt. However, there is still a lack of information about the ectomycorrhizal fungi (EMF) associated with mature individuals of A. glutinosa growing in natural saline conditions. The main objective of this study was to test the effect of soil salinity and other physicochemical parameters on root tips colonized by EMF, as well as on the species richness and diversity of an EMF community associated with A. glutinosa growing in natural conditions. We identified a significant effect of soil salinity (expressed as electrical conductivity: EC e and EC 1:5 ) on fungal taxa but not on the total level of EM fungal colonization on roots. Increasing soil salinity promoted dark-coloured EMF belonging to the order Thelephorales ( Tomentella sp. and Thelephora sp.). These fungi are also commonly found in soils polluted with heavy-metal. The ability of these fungi to grow in contaminated soil may be due to the presence of melanine, a natural dark pigment and common wall component of the Thelephoraceae that is known to act as a protective interface between fungal metabolism and biotic and abiotic environmental stressors. Moreover, increased colonization of fungi belonging to the class of Leotiomycetes and Sordiomycetes, known as endophytic fungal species, was observed at the test sites, that contained a larger content of total phosphorus. This observation confirms the ability of commonly known endophytic fungi to form ectomycorrhizal structures on the roots of A. glutinosa under saline stress conditions.

The hardwood resource in western Oregon.

Treesearch

John H. Poppino; Donald R. Gedney

1984-01-01

The hardwood resource in western Oregon is described by species and ownership. Changes in the private hardwood resource between 1961-62 and 1973-76 are shown. Statistics of size, volume, and ownership by county are presented for red alder (Alnus rubra Bong.) and bigleaf maple (Acer macrophyllum Pursh).

Estimating the susceptibility to Phytophthora alni globally using both statistical analyses and expert knowledge

Treesearch

Marla C. Downing; Thomas Jung; Vernon Thomas; Markus Blaschke; Michael F. Tuffly; Robin Reich

2010-01-01

Phytophthora alni subspecies alni Brasier and S.A. Kirk is a recently hybridized soil and waterborne pathogen causing root and collar rot of species of the genus Alnus spp. (alder). It has quickly spread throughout Europe via planting of infested nursery stock and irrigating fields with infested river...

Toxicity and antioxidant capacity of Frangula alnus Mill. bark and its active component emodin.

PubMed

Brkanac, Sandra Radić; Gerić, Marko; Gajski, Goran; Vujčić, Valerija; Garaj-Vrhovac, Vera; Kremer, Dario; Domijan, Ana-Marija

2015-12-01

In the present study toxicity of Frangula alnus Mill. bark, widely used as laxative, was investigated. Human peripheral blood lymphocytes (HPBLs) were treated with F. alnus bark extract or emodin (emodin is bark component with laxative property), and cytotoxicity, genotoxicity and parameters of oxidative stress were assessed. Also, polyphenol content of bark extract and antioxidant activity of the extract and emodin measured by DPPH, ABTS and FRAP methods were examined. The bark extract (500 μg/ml) produced cell death and DNA damage, while level of ROS changed at 250 μg/ml. Emodin induced cell death and DNA damage at 150 μg/ml and 200 μg/ml, respectively, and the increase of ROS was observed at 25 μg/ml. These results suggest that both, bark extract and emodin, are cyto/genotoxic to HPBLs and that oxidative stress is involved in the mechanism of their toxicity. The results on antioxidant activity showed that, unlike emodin, bark extract possess moderate antioxidant capacity (44.6%, 46.8% and 2.25 mmol Fe(2+)/g measured by DPPH, ABTS and FRAP assay, respectively) that can be related to relatively high phenolic content (116.07 mg/g). However, due to toxicological properties use of F. alnus bark as well as emodin-containing preparations should be taken with caution. Copyright © 2015 Elsevier Inc. All rights reserved.

Diels-Alder Cycloadditions of Masked o-Benzoquinones with Alkenes.

PubMed

Georgopanou, Effie; Martini, Katerina-Irene; Pantazis, Panagiotis; Pelagias, Paulos; Voulgari, Penelope; Hadjiarapoglou, Lazaros P

2015-10-02

Diels-Alder cycloadditions of 3-oxobut-1-enyl substituted orthoquinone monoketals with olefinic dienophiles furnished functionalized ortho-endo bicyclo[2.2.2]octenone derivatives with high regio- and stereoselectivities. The competition between self-dimerization and Diels-Alder cycloaddition with an external dienophile usually exists, except in the case of 5-substituted orthoquinone monoketal.

The role of red alder in riparian forest structure along headwater streams in southeastern Alaska

USGS Publications Warehouse

Orlikowska, E.H.; Deal, R.L.; Hennon, P.E.; Wipfli, M.S.

2004-01-01

We assessed the influence of red alder on tree species composition, stand density, tree size distribution, tree mortality, and potential for producing large conifers, in 38-42 yr old riparian forests along 13 headwater streams in the Maybeso and Harris watersheds on Prince of Wales Island, Alaska. Red alder ranged from 0 to 53% of the total live basal area of the stands. Tree density, basal area of live and dead trees, and mean diameter of live conifers were not significantly related to the percent of alder as a proportion of total stand live basal area within these riparian forests. The mean diameter of the 100 largest conifers per hectare (the largest trees) was similar among different sites and appeared unrelated to the amount of alder in the stands. The mean diameter of dead conifers increased slightly with increasing proportion of red alder. Most dead trees were small and died standing. Red alder was much more concentrated immediately along stream margins (within 0-1 m distance from the stream bank vs. > 1 m). The presence of red alder did not inhibit the production of large-diameter conifers, and both alder and conifers provided small woody debris for fishless headwater streams in southeastern Alaska. Red alder is an important structural component of young-growth riparian stands.

Kunitz-Type Peptide HCRG21 from the Sea Anemone Heteractis crispa Is a Full Antagonist of the TRPV1 Receptor.

PubMed

Monastyrnaya, Margarita; Peigneur, Steve; Zelepuga, Elena; Sintsova, Oksana; Gladkikh, Irina; Leychenko, Elena; Isaeva, Marina; Tytgat, Jan; Kozlovskaya, Emma

2016-12-15

Sea anemone venoms comprise multifarious peptides modulating biological targets such as ion channels or receptors. The sequence of a new Kunitz-type peptide, HCRG21, belonging to the Heteractis crispa RG (HCRG) peptide subfamily was deduced on the basis of the gene sequence obtained from the Heteractis crispa cDNA. HCRG21 shares high structural homology with Kunitz-type peptides APHC1-APHC3 from H. crispa , and clusters with the peptides from so named "analgesic cluster" of the HCGS peptide subfamily but forms a separate branch on the NJ-phylogenetic tree. Three unique point substitutions at the N-terminus of the molecule, Arg1, Gly2, and Ser5, distinguish HCRG21 from other peptides of this cluster. The trypsin inhibitory activity of recombinant HCRG21 (rHCRG21) was comparable with the activity of peptides from the same cluster. Inhibition constants for trypsin and α-chymotrypsin were 1.0 × 10 -7 and 7.0 × 10 -7 M, respectively. Electrophysiological experiments revealed that rHCRG21 inhibits 95% of the capsaicin-induced current through transient receptor potential family member vanilloid 1 (TRPV1) and has a half-maximal inhibitory concentration of 6.9 ± 0.4 μM. Moreover, rHCRG21 is the first full peptide TRPV1 inhibitor, although displaying lower affinity for its receptor in comparison with other known ligands. Macromolecular docking and full atom Molecular Dynamics (MD) simulations of the rHCRG21-TRPV1 complex allow hypothesizing the existence of two feasible, intra- and extracellular, molecular mechanisms of blocking. These data provide valuable insights in the structural and functional relationships and pharmacological potential of bifunctional Kunitz-type peptides.

Two new species of Lactarius associated with Alnus acuminata subsp. arguta in Mexico.

PubMed

Montoya, Leticia; Bandala, Victor M; Garay, Edith

2014-01-01

In pure stands of Alnus acuminata subsp. arguta trees from Sierra Norte de Puebla (central Mexico) two undescribed ectomycorrhizal species of Lactarius were discovered. Distinction of the two new species is based on morphological characters and supported with phylogenetic analyses of the nuclear ribosomal DNA ITS region and part of the gene that encodes for the second largest subunit of RNA polymerase II (rpb2). The phylogenies inferred recovered the two species in different clades strongly supported by posterior probabilities and bootstrap values. The new Lactarius species are recognized as part of the assemblage of ectomycorrhizal fungi associated with Alnus acuminata. Information about these taxa includes the morphological variation achieved along 16 monitories 2010-2013. Descriptions are provided. They are accompanied by photos including SEM photomicrographs of basidiospores and information on differences between them and other related taxa from Europe and the United States. © 2014 by The Mycological Society of America.

Understory plant diversity in riparian alder-conifer stands after logging in southeast Alaska.

Treesearch

Robert L. Deal

1997-01-01

Stand structure, tree height growth, and understory plant diversity were assessed in five mixed alder-conifer stands after logging in southeast Alaska. Tree species composition ranged from 7- to 91-percent alder, and basal area ranged from 30 to 55 m2/ha. The alder exhibited rapid early height growth, but recent growth has slowed considerably. Some conifers have...

Heavy metal stress in alders: Tolerance and vulnerability of the actinorhizal symbiosis.

PubMed

Bélanger, Pier-Anne; Bellenger, Jean-Philippe; Roy, Sébastien

2015-11-01

Alders have already demonstrated their potential for the revegetation of both mining and industrial sites. These actinorhizal trees and shrubs and the actinobacteria Frankia associate in a nitrogen-fixing symbiosis which could however be negatively affected by the presence of heavy metals, and accumulate them. In our hydroponic assay with black alders, quantification of the roots and shoots metal concentrations showed that, in the absence of stress, symbiosis increases Mo and Ni root content and simultaneously decreases Mo shoot content. Interestingly, the Mo shoot content also decreases in the presence of Ni, Cu, Pb, Zn and Cd for symbiotic alders. In symbiotic alders, Pb shoot translocation was promoted in presence of Pb. On the other hand, Cd exclusion in symbiotic root tissues was observed with Pb and Cd. In the presence of symbiosis, only Cd and Pb showed translocation into aerial tissues when present in the nutrient solution. Moreover, the translocation of Ni to shoot was prevented by symbiosis in the presence of Cd, Ni and Pb. The hydroponic experiment demonstrated that alders benefit from the symbiosis, producing more biomass (total, root and shoot) than non nodulated alders in control condition, and in the presence of metals (Cu, Ni, Zn, Pb and Cd). Heavy metals did not reduce the nodule numbers (SNN), but the presence of Zn or Cd did reduce nodule allocation. Our study suggests that the Frankia-alder symbiosis is a promising (and a compatible) plant-microorganism association for the revegetation of contaminated sites, with minimal risk of metal dispersion. Copyright © 2015 Elsevier Ltd. All rights reserved.

The population genomic signature of environmental selection in the widespread insect-pollinated tree species Frangula alnus at different geographical scales

PubMed Central

De Kort, H; Vandepitte, K; Mergeay, J; Mijnsbrugge, K V; Honnay, O

2015-01-01

The evaluation of the molecular signatures of selection in species lacking an available closely related reference genome remains challenging, yet it may provide valuable fundamental insights into the capacity of populations to respond to environmental cues. We screened 25 native populations of the tree species Frangula alnus subsp. alnus (Rhamnaceae), covering three different geographical scales, for 183 annotated single-nucleotide polymorphisms (SNPs). Standard population genomic outlier screens were combined with individual-based and multivariate landscape genomic approaches to examine the strength of selection relative to neutral processes in shaping genomic variation, and to identify the main environmental agents driving selection. Our results demonstrate a more distinct signature of selection with increasing geographical distance, as indicated by the proportion of SNPs (i) showing exceptional patterns of genetic diversity and differentiation (outliers) and (ii) associated with climate. Both temperature and precipitation have an important role as selective agents in shaping adaptive genomic differentiation in F. alnus subsp. alnus, although their relative importance differed among spatial scales. At the ‘intermediate' and ‘regional' scales, where limited genetic clustering and high population diversity were observed, some indications of natural selection may suggest a major role for gene flow in safeguarding adaptability. High genetic diversity at loci under selection in particular, indicated considerable adaptive potential, which may nevertheless be compromised by the combined effects of climate change and habitat fragmentation. PMID:25944466

Enzymatic catalysis of the Diels-Alder reaction in the biosynthesis of natural products.

PubMed

Oikawa, Hideaki; Tokiwano, Tetsuo

2004-06-01

Recent studies on enzymes catalyzing the Diels- Alder reaction. often named "Diels-Alderases", clearlydemonstrated the involvement of this synthetically useful reaction in the biosynthesis of natural products.This review covers natural Diels-Alder type cycloadducts. synthetic efforts on the chemical feasibility ofthe biosynthctic Diels - Alder reaction and a brief history of studies on Diels-Alderases. In addition,reaction mechanisms of artificial and natural Diels--Alderases are discussed.

Kunitz-Type Peptide HCRG21 from the Sea Anemone Heteractis crispa Is a Full Antagonist of the TRPV1 Receptor

PubMed Central

Monastyrnaya, Margarita; Peigneur, Steve; Zelepuga, Elena; Sintsova, Oksana; Gladkikh, Irina; Leychenko, Elena; Isaeva, Marina; Tytgat, Jan; Kozlovskaya, Emma

2016-01-01

Sea anemone venoms comprise multifarious peptides modulating biological targets such as ion channels or receptors. The sequence of a new Kunitz-type peptide, HCRG21, belonging to the Heteractis crispa RG (HCRG) peptide subfamily was deduced on the basis of the gene sequence obtained from the Heteractis crispa cDNA. HCRG21 shares high structural homology with Kunitz-type peptides APHC1–APHC3 from H. crispa, and clusters with the peptides from so named “analgesic cluster” of the HCGS peptide subfamily but forms a separate branch on the NJ-phylogenetic tree. Three unique point substitutions at the N-terminus of the molecule, Arg1, Gly2, and Ser5, distinguish HCRG21 from other peptides of this cluster. The trypsin inhibitory activity of recombinant HCRG21 (rHCRG21) was comparable with the activity of peptides from the same cluster. Inhibition constants for trypsin and α-chymotrypsin were 1.0 × 10−7 and 7.0 × 10−7 M, respectively. Electrophysiological experiments revealed that rHCRG21 inhibits 95% of the capsaicin-induced current through transient receptor potential family member vanilloid 1 (TRPV1) and has a half-maximal inhibitory concentration of 6.9 ± 0.4 μM. Moreover, rHCRG21 is the first full peptide TRPV1 inhibitor, although displaying lower affinity for its receptor in comparison with other known ligands. Macromolecular docking and full atom Molecular Dynamics (MD) simulations of the rHCRG21–TRPV1 complex allow hypothesizing the existence of two feasible, intra- and extracellular, molecular mechanisms of blocking. These data provide valuable insights in the structural and functional relationships and pharmacological potential of bifunctional Kunitz-type peptides. PMID:27983679

The hexadehydro-Diels-Alder reaction.

PubMed

Hoye, Thomas R; Baire, Beeraiah; Niu, Dawen; Willoughby, Patrick H; Woods, Brian P

2012-10-11

Arynes (aromatic systems containing, formally, a carbon-carbon triple bond) are among the most versatile of all reactive intermediates in organic chemistry. They can be 'trapped' to give products that are used as pharmaceuticals, agrochemicals, dyes, polymers and other fine chemicals. Here we explore a strategy that unites the de novo generation of benzynes-through a hexadehydro-Diels-Alder reaction-with their in situ elaboration into structurally complex benzenoid products. In the hexadehydro-Diels-Alder reaction, a 1,3-diyne is engaged in a [4+2] cycloisomerization with a 'diynophile' to produce the highly reactive benzyne intermediate. The reaction conditions for this simple, thermal transformation are notable for being free of metals and reagents. The subsequent and highly efficient trapping reactions increase the power of the overall process. Finally, we provide examples of how this de novo benzyne generation approach allows new modes of intrinsic reactivity to be revealed.

Effects of riparian canopy opening and salmon carcass addition on the abundance and growth of resident salmonids

Treesearch

Margaret A. Wilzbach; Bret C. Harvey; Jason L. White; Rodney J. Nakamoto

2005-01-01

We studied the concurrent effects of riparian canopy opening and salmon carcass addition on salmonid biomass, density and growth rates in small streams over 2 years. In each of six streams in the Smith and Klamath River basins in northern California, red alder (Alnus rubra) and other hardwoods were removed along both banks of a 100-m reach to...

EFFECT OF SIMULATED SULFURIC ACID RAIN ON THE CHEMISTRY OF A SULFATE-ADSORBING FOREST SOIL

EPA Science Inventory

Simulated H2SO4 rain (pH 3.0, 3.5, 4.0) or control rain (pH 5.6) was applied for 3.5 yr to large lysimeter boxes containing a sulfate-adsorbing forest soil and either red alder (Alnus rubra) or sugar maple (Acer saccharum) seedlings. After removal of the plants and the litter lay...

Impact of wind-induced microsites and disturbance severity on tree regeneration patterns: Results from the first post-storm decade

Treesearch

Floor Vodde; Kalev Jogiste; Jeroen Engelhart; Lee E. Frelich; W. Keith Moser; Alan Sims; Marek Metslaid

2015-01-01

In two hemiboreal mixed spruce-hardwood forests in north-east Estonia, we studied (1) which factors affect tree regeneration survival and development during the first post-storm decade and (2) how these effects change in time. Regeneration height and mortality of the tree species black alder (Alnus glutinosa (L.) J. Gaertn.), birch (Betula pendula Roth., Betula...

IFN-gamma induction by SCG, 1,3-beta-D-glucan from Sparassis crispa, in DBA/2 mice in vitro.

PubMed

Harada, Toshie; Miura, Noriko N; Adachi, Yoshiyuki; Nakajima, Mitsuhiro; Yadomae, Toshiro; Ohno, Naohito

2002-12-01

Sparassis crispa Fr. in an edible mushroom recently cultivable in Japan. A branched beta-glucan from S. crispa (SCG) is a major 6-branched 1,3-beta-D-glucan showing antitumor activity. In this study, we examined interferon-gamma (IFN-gamma) induction by SCG from splenocytes in DBA/2 mice in vitro. In the splenocytes derived from almost all inbred strains of mice except for DBA/1 and DBA/2 mice, IFN-gamma production was not induced by SCG. The breeder and genders of DBA/2 mice showed no influence on IFN-gamma induction by SCG. On the other hand, the magnitude of IFN-gamma induction was lower in young mice than in their older counterparts. IFN-gamma was induced by SCG in adherent splenocytes, but IFN-gamma production was most significantly increased by SCG in instances involving coexistence of adherent and nonadherent splenocytes. In fact, inhibition of cell-cell contact reduced IFN-gamma induction by SCG. In addition, interleukin-12 p70 (IL-12p70) was induced by SCG in DBA/2 mice. It was suggested that soluble factors and cell-cell contact mediate synergistic effects on SCG-induced IFN-gamma production.

Alnus maritime ssp. oklahomensis performance in non-irrigated landscapes in the Intermountain West

Treesearch

Heidi A. Kratsch

2008-01-01

Alnus maritima (Marsh.) Muhl. ex Nutt. ssp. oklahomensis Schrader & Graves has potential for ornamental use in the Intermountain West. Because this taxon is native to low-elevation wetlands, we sought to determine its response to the dry soils and climate of northern Utah. Although seeds sown directly at three non-irrigated sites in northern Utah either did not...

Growth response of speckled alder and willow to depth of flooding

Treesearch

M. Dean Knighton

1981-01-01

Growth and survival of speckled alder and willow were determined for two growing seasons with continuous flooding at different depths. Growth was at least four times greater when the water table was below the root crown than when it was 15 cm above. Mortality increased with flooding depth and as greatest for alder.

Physiological effects of major up-regulated Alnus glutinosa peptides on Frankia sp. ACN14a.

PubMed

Carro, Lorena; Pujic, Petar; Alloisio, Nicole; Fournier, Pascale; Boubakri, Hasna; Poly, Franck; Rey, Marjolaine; Heddi, Abdelaziz; Normand, Philippe

2016-07-01

Alnus glutinosa has been shown previously to synthesize, in response to nodulation by Frankia sp. ACN14a, an array of peptides called Alnus symbiotic up-regulated peptides (ASUPs). In a previous study one peptide (Ag5) was shown to bind to Frankia nitrogen-fixing vesicles and to modify their porosity. Here we analyse four other ASUPs, alongside Ag5, to determine whether they have different physiological effects on in vitro grown Frankia sp. ACN14a. The five studied peptides were shown to have different effects on nitrogen fixation, respiration, growth, the release of ions and amino acids, as well as on cell clumping and cell lysis. The mRNA abundance for all five peptides was quantified in symbiotic nodules and one (Ag11) was found to be more abundant in the meristem part of the nodule. These findings point to some peptides having complementary effects on Frankia cells.

The hexane fraction of Ardisia crispa Thunb. A. DC. roots inhibits inflammation-induced angiogenesis

PubMed Central

2013-01-01

Background Ardisia crispa (Myrsinaceae) is used in traditional Malay medicine to treat various ailments associated with inflammation, including rheumatism. The plant’s hexane fraction was previously shown to inhibit several diseases associated with inflammation. As there is a strong correlation between inflammation and angiogenesis, we conducted the present study to investigate the anti-angiogenic effects of the plant’s roots in animal models of inflammation-induced angiogenesis. Methods We first performed phytochemical screening and high-performance liquid chromatography (HPLC) fingerprinting of the hexane fraction of Ardisia crispa roots ethanolic extract (ACRH) and its quinone-rich fraction (QRF). The anti-inflammatory properties of ACRH and QRF were tested using the Miles vascular permeability assay and the murine air pouch granuloma model following oral administration at various doses. Results Preliminary phytochemical screening of ACRH revealed the presence of flavonoids, triterpenes, and tannins. The QRF was separated from ACRH (38.38% w/w) by column chromatography, and was isolated to yield a benzoquinonoid compound. The ACRH and QRF were quantified by HPLC. The LD50 value of ACRH was 617.02 mg/kg. In the Miles vascular permeability assay, the lowest dose of ACRH (10 mg/kg) and all doses of QRF significantly reduced vascular endothelial growth factor (VEGF)-induced hyperpermeability, when compared with the vehicle control. In the murine air pouch granuloma model, ACRH and QRF both displayed significant and dose-dependent anti-inflammatory effects, without granuloma weight. ACRH and QRF significantly reduced the vascular index, but not granuloma tissue weight. Conclusions In conclusion, both ACRH and QRF showed potential anti-inflammatory properties in a model of inflammation-induced angiogenesis model, demonstrating their potential anti-angiogenic properties. PMID:23298265

Anticholinesterase inhibitory activity of quaternary alkaloids from Tinospora crispa.

PubMed

Yusoff, Mashitah; Hamid, Hazrulrizawati; Houghton, Peter

2014-01-20

Quaternary alkaloids are the major alkaloids isolated from Tinospora species. A previous study pointed to the necessary presence of quaternary nitrogens for strong acetylcholinesterase (AChE) inhibitory activity in such alkaloids. Repeated column chromatography of the vine of Tinospora crispa extract led to the isolation of one new protoberberine alkaloid, 4,13-dihydroxy-2,8,9-trimethoxydibenzo[a,g]quinolizinium (1), along with six known alkaloids-dihydrodiscretamine (2), columbamine (3), magnoflorine (4), N-formylannonaine (5), N-formylnornuciferine (6), and N-trans-feruloyltyramine (7). The seven compounds were isolated and structurally elucidated by spectroscopic analysis. Two known alkaloids, namely, dihydrodiscretamine and columbamine are reported for the first time for this plant. The compounds were tested for AChE inhibitory activity using Ellman's method. In the AChE inhibition assay, only columbamine (3) showed strong activity with IC50 48.1 µM. The structure-activity relationships derived from these results suggest that the quaternary nitrogen in the skeleton has some effect, but that a high degree of methoxylation is more important for acetylcholinesterase inhibition.

An Appreciation: Berni Julian Alder

NASA Astrophysics Data System (ADS)

Graham Hoover, William

Berni Alder profoundly influenced my research career at Lawrence Livermore National Laboratory and the Davis Campus' Teller Tech, beginning in 1962 and lasting for over fifty years. I very much appreciate the opportunity provided by his Ninetieth Birthday Celebration to review some of the many high spots along the way.

Red alder harvesting opportunities in western Oregon.

Treesearch

Donald R. Gedney

1990-01-01

This report presents statistics on the present distribution and ownership of merchantable stands of red alder in western Oregon and the character of these stands as they affect harvesting opportunities.

Temporal and spatiotemporal autocorrelation of daily concentrations of Alnus, Betula, and Corylus pollen in Poland.

PubMed

Nowosad, J; Stach, A; Kasprzyk, I; Grewling, Ł; Latałowa, M; Puc, M; Myszkowska, D; Weryszko-Chmielewska, E; Piotrowska-Weryszko, K; Chłopek, K; Majkowska-Wojciechowska, B; Uruska, A

The aim of the study was to determine the characteristics of temporal and space-time autocorrelation of pollen counts of Alnus , Betula , and Corylus in the air of eight cities in Poland. Daily average pollen concentrations were monitored over 8 years (2001-2005 and 2009-2011) using Hirst-designed volumetric spore traps. The spatial and temporal coherence of data was investigated using the autocorrelation and cross-correlation functions. The calculation and mathematical modelling of 61 correlograms were performed for up to 25 days back. The study revealed an association between temporal variations in Alnus , Betula , and Corylus pollen counts in Poland and three main groups of factors such as: (1) air mass exchange after the passage of a single weather front (30-40 % of pollen count variation); (2) long-lasting factors (50-60 %); and (3) random factors, including diurnal variations and measurements errors (10 %). These results can help to improve the quality of forecasting models.

Growth and Survival of Hardwoods and Pine Interplanted with European Alder

Treesearch

William T. Plass

1977-01-01

European black alder is recommended for planting on many surface mine spoils in the eastern United States. It grows rapidly on a range of spoil types and contributes to soil enrichment by fixing nitrogen and providing a leaf fall rich in nutrients. This study evaluated the effect of alder on the survival and growth of five hardwood and five pine species. After 10...

Comparative effects of precommercial thinning, urea fertilizer, and red alder in a site II, coast Douglas-fir plantation.

Treesearch

Richard E. Miller; Edmund L. Obermeyer; Harry W. Anderson

1999-01-01

We varied the number of red alder retained with 300 Douglas-fir per acre on a high-quality site in coastal Oregon. Alder densities of 0, 20, 40, and 80 per acre were tested. Our fifth treatment eliminated nitrogen-fixing alder, but substituted nitrogen fertilizer. Treatment 6 had neither thinning nor alder control. Treatments were randomly assigned within each of three...

Diels–Alder cycloaddition of 2-methylfuran and ethylene for renewable toluene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Green, Sara K.; Patet, Ryan E.; Nikbin, Nima

Diels–Alder cycloaddition of biomass-derived 2-methylfuran and ethylene provides a thermochemical pathway to renewable toluene. In this work, the kinetics and reaction pathways of toluene formation have been evaluated with H-BEA and Sn-BEA catalysts. Kinetic analysis of the main reaction chemistries reveals the existence of two rate-controlling reactions: (i) Diels–Alder cycloaddition of 2-methylfuran and ethylene where the production rate is independent of the Brønsted acid site concentration, and (ii) dehydration of the Diels–Alder cycloadduct where the production rate is dependent on the Brønsted acid site concentration. Application of a reduced kinetic model supports the interplay of these two regimes with themore » highest concentration of toluene measured at a catalyst loading equal to the transition region between the two kinetic regimes. Selectivity to toluene never exceeded 46%, as 2-methylfuran was consumed by several newly identified reactions to side products, including dimerization of 2-methylfuran, the formation of a trimer following hydrolysis and ring-opening of 2-methylfuran, and the incomplete dehydration of the Diels–Alder cycloadduct of 2-methylfuran and ethylene.« less

New APETx-like peptides from sea anemone Heteractis crispa modulate ASIC1a channels.

PubMed

Kalina, Rimma; Gladkikh, Irina; Dmitrenok, Pavel; Chernikov, Oleg; Koshelev, Sergey; Kvetkina, Aleksandra; Kozlov, Sergey; Kozlovskaya, Emma; Monastyrnaya, Margarita

2018-06-01

Sea anemones are an abundant source of various biologically active peptides. The hydrophobic 20% ethanol fraction of tropical sea anemone Heteractis crispa was shown to contain at least 159 peptide compounds including neurotoxins, proteinase and α-amylase inhibitors, as well as modulators of acid-sensing ion channels (ASICs). The three new peptides, π-AnmTX Hcr 1b-2, -3, and -4 (41 aa) (short names Hcr 1b-2, -3, -4), identified by a combination of reversed-phase liquid chromatography and mass spectrometry were found to belong to the class 1b sea anemone neurotoxins. The amino acid sequences of these peptides were determined by Edman degradation and tandem mass spectrometry. The percent of identity of Hcr 1b-2, -3, and -4 with well-known ASIC3 inhibitors Hcr 1b-1 from H. crispa and APETx2 from Anthopleura elegantissima is 95-78% and 46-49%, respectively. Electrophysiological experiments on homomeric ASIC channels expressed in Xenopus laevis oocytes establish that these peptides are the first inhibitors of ASIC1a derived from sea anemone venom. The major peptide, Hcr 1b-2, inhibited both rASIC1a (IC 50 4.8 ± 0.3 μM; nH 0.92 ± 0.05) and rASIC3 (IC 50 15.9 ± 1.1 μM; nH 1.0 ± 0.05). The maximum inhibition at saturating peptide concentrations reached 64% and 81%, respectively. In the model of acid-induced muscle pain Hcr 1b-2 was also shown to exhibit an antihyperalgesic effect, significantly reducing of the pain threshold of experimental animals. Copyright © 2018 Elsevier Inc. All rights reserved.

Computational design of an enzyme catalyst for a stereoselective bimolecular Diels-Alder reaction.

PubMed

Siegel, Justin B; Zanghellini, Alexandre; Lovick, Helena M; Kiss, Gert; Lambert, Abigail R; St Clair, Jennifer L; Gallaher, Jasmine L; Hilvert, Donald; Gelb, Michael H; Stoddard, Barry L; Houk, Kendall N; Michael, Forrest E; Baker, David

2010-07-16

The Diels-Alder reaction is a cornerstone in organic synthesis, forming two carbon-carbon bonds and up to four new stereogenic centers in one step. No naturally occurring enzymes have been shown to catalyze bimolecular Diels-Alder reactions. We describe the de novo computational design and experimental characterization of enzymes catalyzing a bimolecular Diels-Alder reaction with high stereoselectivity and substrate specificity. X-ray crystallography confirms that the structure matches the design for the most active of the enzymes, and binding site substitutions reprogram the substrate specificity. Designed stereoselective catalysts for carbon-carbon bond-forming reactions should be broadly useful in synthetic chemistry.

Changes in sediment volume in Alder Lake, Nisqually River Basin, Washington, 1945-2011

USGS Publications Warehouse

Czuba, Jonathan A.; Olsen, Theresa D.; Czuba, Christiana R.; Magirl, Christopher S.; Gish, Casey C.

2012-01-01

The Nisqually River drains the southwest slopes of Mount Rainier, a glaciated stratovolcano in the Cascade Range of western Washington. The Nisqually River was impounded behind Alder Dam when the dam was completed in 1945 and formed Alder Lake. This report quantifies the volume of sediment deposited by the Nisqually and Little Nisqually Rivers in their respective deltas in Alder Lake since 1945. Four digital elevation surfaces were generated from historical contour maps from 1945, 1956, and 1985, and a bathymetric survey from 2011. These surfaces were used to compute changes in sediment volume since 1945. Estimates of the volume of sediment deposited in Alder Lake between 1945 and 2011 were focused in three areas: (1) the Nisqually River delta, (2) the main body of Alder Lake, along a 40-meter wide corridor of the pre-dam Nisqually River, and (3) the Little Nisqually River delta. In each of these areas the net deposition over the 66-year period was 42,000,000 ± 4,000,000 cubic meters (m3), 2,000,000 ± 600,000 m3, and 310,000 ± 110,000 m3, respectively. These volumes correspond to annual rates of accumulation of 630,000 ± 60,000 m3/yr, 33,000 ± 9,000 m3/yr, and 4,700 ± 1,600 m3/yr, respectively. The annual sediment yield of the Nisqually (1,100 ± 100 cubic meters per year per square kilometer [(m3/yr)/km2]) and Little Nisqually River basins [70 ± 24 (m3/yr)/km2] provides insight into the yield of two basins with different land cover and geomorphic processes. These estimates suggest that a basin draining a glaciated stratovolcano yields approximately 15 times more sediment than a basin draining forested uplands in the Cascade Range. Given the cumulative net change in sediment volume in the Nisqually River delta in Alder Lake, the total capacity of Alder Lake since 1945 decreased about 3 percent by 1956, 8 percent by 1985, and 15 percent by 2011.

Computational design of an enzyme catalyst for a stereoselective bimolecular Diels-Alder reaction

PubMed Central

Siegel, Justin B.; Zanghellini, Alexandre; Lovick, Helena M.; Kiss, Gert; Lambert, Abigail R.; St.Clair, Jennifer L.; Gallaher, Jasmine L.; Hilvert, Donald; Gelb, Michael H.; Stoddard, Barry L.; Houk, Kendall N.; Michael, Forrest E.; Baker, David

2011-01-01

The Diels-Alder reaction is a cornerstone in organic synthesis, forming two carbon-carbon bonds and up to four new stereogenic centers in one step. No naturally occurring enzymes have been shown to catalyze bimolecular Diels-Alder reactions. We describe the de novo computational design and experimental characterization of enzymes catalyzing a bimolecular Diels-Alder reaction with high stereoselectivity and substrate specificity. X-ray crystallography confirms that the structure matches the design for the most active of the enzymes, and binding site substitutions reprogram the substrate specificity. Designed stereoselective catalysts for carbon-carbon bond forming reactions should be broadly useful in synthetic chemistry. PMID:20647463

Theoretical study of the Diels-Alder reaction between o-benzoquinone and norbornadiene

NASA Astrophysics Data System (ADS)

Quijano-Quiñones, Ramiro F.; Quesadas-Rojas, M.; Cuevas, Gabriel; Mena-Rejón, Gonzalo J.

2013-06-01

The reaction between norbornadiene and o-benzoquinone is an important step in polyalicyclic rigid structures synthesis. It has been considered that this reaction is an example of Diels-Alder (DA) and hetero-Diels-Alder (HDA) cycloadditions with o-benzoquinone acting as diene (forming C-C bonds) and heterodiene (forming O-C bonds). We have performed a Density Functional Theory study of this reaction, employing B3LYP, mPW1PW91, and B1B95 functionals and 6-31G(d,p) and 6-31+G(d,p) Gaussian type basis sets. The results indicate that Diels-Alder is a feasible mechanism for both reactions, but should not be the main route to the formation of products with C-C bonds.

Welcome and Reflections on Berni Alder

NASA Astrophysics Data System (ADS)

Tarter, C. Bruce

Good morning and welcome to Berni Alder's 90th Birthday Symposium. My name is Bruce Tarter and I'm representing Director Bill Goldstein, who could not be here this morning, but will be here for the afternoon session and will make comments of his own at the end of the Symposium…

N2-fixing red alder indirectly accelerates ecosystem nitrogen cycling

USGS Publications Warehouse

Perakis, Steven S.; Matkins, Joselin J.; Hibbs, David E.

2012-01-01

Symbiotic N2-fixing tree species can accelerate ecosystem N dynamics through decomposition via direct pathways by producing readily decomposed leaf litter and increasing N supply to decomposers, as well as via indirect pathways by increasing tissue and detrital N in non-fixing vegetation. To evaluate the relative importance of these pathways, we compared three-year decomposition and N dynamics of N2-fixing red alder leaf litter (2.34 %N) to both low-N (0.68 %N) and high-N (1.21 %N) litter of non-fixing Douglas-fir, and decomposed each litter source in four forests dominated by either red alder or Douglas-fir. We also used experimental N fertilization of decomposition plots to assess elevated N availability as a potential mechanism of N2-fixer effects on litter mass loss and N dynamics. Direct effects of N2-fixing red alder on decomposition occurred primarily as faster N release from red alder than Douglas-fir litter, but direct increases in N supply to decomposers via fertilization did not stimulate decomposition of any litter. Fixed N indirectly influenced detrital dynamics by increasing Douglas-fir tissue and litter N concentrations, which accelerated litter N release without accelerating mass loss. By increasing soil N, tissue N, and the rate of N release from litter of non-fixers, we conclude that N2-fixing vegetation can indirectly foster plant-soil feedbacks that contribute to the persistence of elevated N availability in terrestrial ecosystems.

Forecasting model of Corylus, Alnus, and Betula pollen concentration levels using spatiotemporal correlation properties of pollen count.

PubMed

Nowosad, Jakub; Stach, Alfred; Kasprzyk, Idalia; Weryszko-Chmielewska, Elżbieta; Piotrowska-Weryszko, Krystyna; Puc, Małgorzata; Grewling, Łukasz; Pędziszewska, Anna; Uruska, Agnieszka; Myszkowska, Dorota; Chłopek, Kazimiera; Majkowska-Wojciechowska, Barbara

The aim of the study was to create and evaluate models for predicting high levels of daily pollen concentration of Corylus , Alnus , and Betula using a spatiotemporal correlation of pollen count. For each taxon, a high pollen count level was established according to the first allergy symptoms during exposure. The dataset was divided into a training set and a test set, using a stratified random split. For each taxon and city, the model was built using a random forest method. Corylus models performed poorly. However, the study revealed the possibility of predicting with substantial accuracy the occurrence of days with high pollen concentrations of Alnus and Betula using past pollen count data from monitoring sites. These results can be used for building (1) simpler models, which require data only from aerobiological monitoring sites, and (2) combined meteorological and aerobiological models for predicting high levels of pollen concentration.

The Diels-Alder cyclization of ketenimines.

PubMed

Erb, Jeremy; Strull, Jessica; Miller, David; He, Jean; Lectka, Thomas

2012-04-20

A Diels-Alder reaction between cyclopentadiene and a variety of ketenimines is reported. A copper(I)-bis(phosphine complex catalyzes the cycloaddition across the C═N bond of the ketenimine in a [4 + 2] reaction to give an enamine intermediate that is hydrolyzed upon purification to generate aminoketones. © 2012 American Chemical Society

Growth, nitrogen fixation and mineral acquisition of Alnus sieboldiana after inoculation of Frankia together with Gigaspora margarita and Pseudomonas putida.

Treesearch

Takashi Yamanaka; Akio Akama; Ching-Yan Li; Hiroaki Okabe

2005-01-01

The role of tetrapartite associations among Frankia, Gigaspora margarita (an arbuscular mycorrhizal fungus), Pseudomonas putida (rhizobacterium), and Alnus sieboldiana in growth, nitrogen fixation, and mineral acquisition of A. sieboldiana was investigated....

Diels–Alder reactions of myrcene using intensified continuous-flow reactors

PubMed Central

Álvarez-Diéguez, Miguel Á; Kohl, Thomas M; Tsanaktsidis, John

2017-01-01

This work describes the Diels–Alder reaction of the naturally occurring substituted butadiene, myrcene, with a range of different naturally occurring and synthetic dienophiles. The synthesis of the Diels–Alder adduct from myrcene and acrylic acid, containing surfactant properties, was scaled-up in a plate-type continuous-flow reactor with a volume of 105 mL to a throughput of 2.79 kg of the final product per day. This continuous-flow approach provides a facile alternative scale-up route to conventional batch processing, and it helps to intensify the synthesis protocol by applying higher reaction temperatures and shorter reaction times. PMID:28228853

Host species and habitat affect nodulation by specific Frankia genotypes in two species of Alnus in interior Alaska

Treesearch

Michael Damon Anderson; Roger W. Ruess; David D. Myrold; D. Lee Taylor

2009-01-01

This study examined the genetic structure (nifD-K spacer RFLP haplotypes) of Frankia assemblages symbiotic with two species of Alnus (A. tenuifolia and A. viridis) in four successional habitats in interior Alaska. We used one habitat in which both hosts occurred to...

Biology and ecology of red alder.

Treesearch

Constance A. Harrington

2006-01-01

Red alder is the most common hardwood in the Pacific Northwest with a range stretching from coastal southeast Alaska to southern California and east to isolated populations in Idaho. Soil moisture during the growing season influences where it grows and its growth rates; it can tolerate poor drainage but not droughty, hot sites. Due to its tolerance of wet soil...

Seasonal patterns of climate controls over nitrogen fixation by Alnus viridis subsp

Treesearch

Jennifer S. Mitchell; Roger W. Ruess

2009-01-01

Patterns of and controls over N2 fixation by green alder were studied in post-fire, mid-succession, and white spruce upland forests in interior Alaska, focusing on the hypothesis that ecosystem-level nitrogen (N) inputs decrease with successional development. N2-fixation rates tracked plant phenology during the 1997 (...

A Diels-Alder Route to Angularly Functionalized Bicyclic Structures

PubMed Central

Kim, Woo Han; Lee, Jun Hee; Aussedat, Baptiste; Danishefsky, Samuel J.

2010-01-01

A Diels-Alder based route to trans-fused angularly functionalized bicyclic structures has been developed. This transformation features the use of a tetrasubstituted dienophile in the cycloaddition step. PMID:20717474

Interspecific Plant Interactions Reflected in Soil Bacterial Community Structure and Nitrogen Cycling in Primary Succession.

PubMed

Knelman, Joseph E; Graham, Emily B; Prevéy, Janet S; Robeson, Michael S; Kelly, Patrick; Hood, Eran; Schmidt, Steve K

2018-01-01

Past research demonstrating the importance plant-microbe interactions as drivers of ecosystem succession has focused on how plants condition soil microbial communities, impacting subsequent plant performance and plant community assembly. These studies, however, largely treat microbial communities as a black box. In this study, we sought to examine how emblematic shifts from early successional Alnus viridus ssp. sinuata (Sitka alder) to late successional Picea sitchensis (Sitka spruce) in primary succession may be reflected in specific belowground changes in bacterial community structure and nitrogen cycling related to the interaction of these two plants. We examined early successional alder-conditioned soils in a glacial forefield to delineate how alders alter the soil microbial community with increasing dominance. Further, we assessed the impact of late-successional spruce plants on these early successional alder-conditioned microbiomes and related nitrogen cycling through a leachate addition microcosm experiment. We show how increasingly abundant alder select for particular bacterial taxa. Additionally, we found that spruce leachate significantly alters the composition of these microbial communities in large part by driving declines in taxa that are enriched by alder, including bacterial symbionts. We found these effects to be spruce specific, beyond a general leachate effect. Our work also demonstrates a unique influence of spruce on ammonium availability. Such insights bolster theory relating the importance of plant-microbe interactions with late-successional plants and interspecific plant interactions more generally.

Interspecific Plant Interactions Reflected in Soil Bacterial Community Structure and Nitrogen Cycling in Primary Succession

PubMed Central

Knelman, Joseph E.; Graham, Emily B.; Prevéy, Janet S.; Robeson, Michael S.; Kelly, Patrick; Hood, Eran; Schmidt, Steve K.

2018-01-01

Past research demonstrating the importance plant–microbe interactions as drivers of ecosystem succession has focused on how plants condition soil microbial communities, impacting subsequent plant performance and plant community assembly. These studies, however, largely treat microbial communities as a black box. In this study, we sought to examine how emblematic shifts from early successional Alnus viridus ssp. sinuata (Sitka alder) to late successional Picea sitchensis (Sitka spruce) in primary succession may be reflected in specific belowground changes in bacterial community structure and nitrogen cycling related to the interaction of these two plants. We examined early successional alder-conditioned soils in a glacial forefield to delineate how alders alter the soil microbial community with increasing dominance. Further, we assessed the impact of late-successional spruce plants on these early successional alder-conditioned microbiomes and related nitrogen cycling through a leachate addition microcosm experiment. We show how increasingly abundant alder select for particular bacterial taxa. Additionally, we found that spruce leachate significantly alters the composition of these microbial communities in large part by driving declines in taxa that are enriched by alder, including bacterial symbionts. We found these effects to be spruce specific, beyond a general leachate effect. Our work also demonstrates a unique influence of spruce on ammonium availability. Such insights bolster theory relating the importance of plant–microbe interactions with late-successional plants and interspecific plant interactions more generally. PMID:29467741

Fe(II)/Fe(III)-Catalyzed Intramolecular Didehydro-Diels-Alder Reaction of Styrene-ynes.

PubMed

Mun, Hyeon Jin; Seong, Eun Young; Ahn, Kwang-Hyun; Kang, Eun Joo

2018-02-02

The intramolecular didehydro-Diels-Alder reaction of styrene-ynes was catalyzed by Fe(II) and Fe(III) to produce various naphthalene derivatives under microwave heating conditions. Mechanistic calculations found that the Fe(II) catalyst activates the styrenyl diene in an inverse-electron-demand Diels-Alder reaction, and the consecutive dehydrogenation reaction can be promoted by either Fe(II)-catalyzed direct dehydrogenation or an Fe(III)-catalyzed rearomatization/dehydrogenation pathway.

Effects of invasive European bird cherry (Prunus padus) on leaf litter processing by aquatic invertebrate shredder communities in urban Alaskan streams

USGS Publications Warehouse

Roon, David A.; Wipfli, Mark S.; Wurtz, Tricia L.

2014-01-01

European bird cherry (Prunus padus) (EBC) is an invasive ornamental tree that is spreading rapidly in riparian forests of urban Alaska. To determine how the spread of EBC affects leaf litter processing by aquatic invertebrate shredders, we conducted complementary leaf pack experiments in two streams located in Anchorage, Alaska. The first experiment contrasted invasive EBC with three native tree species—thin-leaf alder (Alnus tenuifolia), paper birch (Betula neoalaskana), and black cottonwood (Populus trichocarpa)—in one reach of Chester Creek; finding that EBC leaf litter broke down significantly faster than birch and cottonwood, but at a similar rate to alder. The second experiment contrasted EBC with alder in four reaches of Campbell and Chester creeks; finding that while EBC leaf litter broke down significantly faster than alder in Chester Creek, EBC broke down at a similar rate to alder in Campbell Creek. Although EBC sometimes supported fewer shredders by both count and mass, shredder communities did not differ significantly between EBC and native plants. Collectively, these data suggest that invasive EBC is not currently exhibiting strong negative impacts on leaf litter processing in these streams, but could if it continues to spread and further displaces native species over time.

Cultural Resources Reconnaissance Study of the Black Warrior-Tombigbee System Corridor, Alabama. Volume 1. Archaeology.

DTIC Science & Technology

1983-01-01

hazel alder (Alnus serrulata), and lead plant (Amerpha fruticasa) often gain dominance on low stream banks. A great variety of woody vines groww in...Early Archaic ecosystems for the Midwest may be highly signifi- cant. From 8000 to about 5000 B.P. in southwest Alabama mobile groups apparently...n-48) of the Gulf Formational or Early Woodland sites within the BWT project area. Middle to Late Woodi -nd Site Locations The summary locational

Fourfold Diels-Alder reaction of tetraethynylsilane.

PubMed

Geyer, Florian L; Rode, Alexander; Bunz, Uwe H F

2014-12-08

A series of ethynylated silanes, including tetraethynylsilane, was treated with tetraphenylcyclopentadienone at 300 °C under microwave irradiation to give the aromatized Diels-Alder adducts as sterically encumbered mini-dendrimers with up to 20 benzene rings. The sterically most congested adducts display red-shifted emission through intramolecular π-π interactions in the excited state. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interspecific Plant Interactions Reflected in Soil Bacterial Community Structure and Nitrogen Cycling in Primary Succession

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knelman, Joseph E.; Graham, Emily B.; Prevéy, Janet S.

Past research demonstrating the importance plant-microbe interactions as drivers of ecosystem succession has focused on how plants condition soil microbial communities, impacting subsequent plant performance and successional trajectories in plant community assembly. These studies, however, largely treat microbial communities as a black box. In this study we sought to examine how emblematic shifts from early-successional Alnus sinuata (alder) to late successional Picea sitchensis (spruce) in primary succession may be reflected in specific belowground changes in bacterial community structure and nitrogen cycling related to the interaction of these two plants. We examined early successional alder-conditioned soils in a glacial forefield tomore » delineate how alders alter the soil microbial community with increasing dominance. Further, we assessed the impact of late-successional spruce plants on these early-successional alder-conditioned microbiomes and related nitrogen cycling through a leachate addition microcosm experiment. We show how increasingly abundant alder select for particular bacterial taxa. Additionally, we found that spruce leachate drives shifts in the relative abundance of major taxa of bacteria in alder-influenced soils, including declines in those that are enriched by alder. We found these effects to be spruce-specific, beyond a general leachate effect. Our work also demonstrates a unique influence of spruce on ammonium availability. Our results show that spruce leachate addition more strongly structures bacterial communities than alders (less dispersion in bacterial community beta diversity). Such insights bolster theory relating the importance of plant-microbe interactions with late-successional plants and interspecific plant interactions more generally.« less

A recyclable fluorous organocatalyst for Diels-Alder reactions

PubMed Central

Chu, Qianli; Zhang, Wei; Curran, Dennis P.

2007-01-01

Chiral fluorous imidazolidinone catalyst 2 provides consistently high enantioselectivities in Diels-Alder reactions of dienes and α, β-unsaturated aldehydes. The catalyst can be readily separated from the reaction products by fluorous solid-phase extraction, and recovered in excellent purity for direct reuse. PMID:17710220

Nature's Strategy for Catalyzing Diels-Alder Reaction.

PubMed

Oikawa, Hideaki

2016-04-21

The enzymes catalyzing a Diels-Alder-type reaction have been attractive targets for organic chemists for years. Recently, Zheng et al. (2016) reported the structure of a formal monofunctional Diels-Alderase PyrI4 complexed with the product and unveiled a detailed catalytic mechanism of a highly important enzyme. Copyright © 2016 Elsevier Ltd. All rights reserved.

High perfomance liquid chromatography fingerprint analysis for quality control of brotowali (Tinospora crispa)

NASA Astrophysics Data System (ADS)

Syarifah, V. B.; Rafi, M.; Wahyuni, W. T.

2017-05-01

Brotowali (Tinospora crispa) is widely used in Indonesia as ingredient of herbal medicine formulation. To ensure the quality, safety, and efficacy of herbal medicine products, its chemical constituents should be continuously evaluated. High performance liquid chromatography (HPLC) fingerprint is one of powerful technique for this quality control process. In this study, HPLC fingerprint analysis method was developed for quality control of brotowali. HPLC analysis was performed in C18 column and detection was performed using photodiode array detector. The optimum mobile phase for brotowali fingerprint was acetonitrile (ACN) and 0.1% formic acid in gradient elution mode at a flow rate of 1 mL/min. The number of peaks detected in HPLC fingerprint of brotowali was 32 peaks and 23 peaks for stems and leaves, respectively. Berberine as marker compound was detected at retention time of 20.525 minutes. Evaluation of analytical performance including precision, reproducibility, and stability prove that this HPLC fingerprint analysis was reliable and could be applied for quality control of brotowali.

Covalently crosslinked diels-alder polymer networks.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowman, Christopher; Adzima, Brian J.; Anderson, Benjamin John

2011-09-01

This project examines the utility of cycloaddition reactions for the synthesis of polymer networks. Cycloaddition reactions are desirable because they produce no unwanted side reactions or small molecules, allowing for the formation of high molecular weight species and glassy crosslinked networks. Both the Diels-Alder reaction and the copper-catalyzed azide-alkyne cycloaddition (CuAAC) were studied. Accomplishments include externally triggered healing of a thermoreversible covalent network via self-limited hysteresis heating, the creation of Diels-Alder based photoresists, and the successful photochemical catalysis of CuAAC as an alternative to the use of ascorbic acid for the generation of Cu(I) in click reactions. An analysis ofmore » the results reveals that these new methods offer the promise of efficiently creating robust, high molecular weight species and delicate three dimensional structures that incorporate chemical functionality in the patterned material. This work was performed under a Strategic Partnerships LDRD during FY10 and FY11 as part of a Sandia National Laboratories/University of Colorado-Boulder Excellence in Science and Engineering Fellowship awarded to Brian J. Adzima, a graduate student at UC-Boulder. Benjamin J. Anderson (Org. 1833) was the Sandia National Laboratories point-of-contact for this fellowship.« less

Berni Alder and Phase Transitions in Two Dimensions

NASA Astrophysics Data System (ADS)

Kosterlitz, J. Michael

I do not know Berni Alder as a person, but I feel that I know him well through his seminal paper "Phase Transition in Elastic Disks𠇍 by B. J. Alder and T. E. Wainwright [1962], which was essential in motivating David Thouless and myself to think about phase transitions in two dimensional systems with a continuous symmetry. In the early 1970's, the conventional wisdom was that a crystalline solid could not exist in a two dimensional world because of the rigorous Mermin-Wagner theorem prohibiting true long range translational order at any non-zero temperature. This contradiction was settled by the theory of dislocation mediated melting to an intermediate hexatic phase followed by a second transition to the isotropic fluid at a higher temperature. This scenario, with its associated sophisticated theory, seemed to settle the controversy of two dimensional melting once and for all. However, in our elation at understanding the fundamental physics and the essential excitations of melting in 2D, we had all forgotten that the early work of Berni Alder also showed that this melting involved a weak first order transition while theory now predicted melting by two successive continuous transitions with no discontinuity in area at the critical pressure. This discrepancy could be hand waved away by arguing that Berni's system was far too small and his computers far too slow so that the areal discontinuity could be due to finite size effects or to failing to equilibrate the system. Experiments were not able to resolve the order of the transitions, but seemed to agree quantitatively with theory…

Early survival and growth of planted Douglas-fir with red alder in four mixed regimes.

Treesearch

Marshall D. Murray; Richard E. Miller

1986-01-01

To quantify between-species interactions, we measured and compared survival and growth of planted Douglas-fir and associated planted and volunteer red alder at a location on the west side of the Cascade Range in Washington. The planted alder were wildlings dug either from a nearby area or from a distant, coastal site and interplanted into a 3-year-old Douglas-fir...

A preliminary study of the deterioration of alder and Douglas-fir chips in outdoor piles.

Treesearch

Ernest. Wright

1954-01-01

In the fall of 1952, E. E. Matson of the Pacific Northwest Forest and Range Experiment Station learned that the Fir-Tex Insulating Board Company bf St. Helens, Oregon was considering mixing alder with Douglas-fir chips for outside storage. Since alder heartwood i s more susceptible to decay than that of Douglas-fir, the question arose whether mixing the two might...

The Preparation and Properties of Thermo-reversibly Cross-linked Rubber Via Diels-Alder Chemistry.

PubMed

Polgar, Lorenzo Massimo; van Duin, Martin; Picchioni, Francesco

2016-08-25

A method for using Diels Alder thermo-reversible chemistry as cross-linking tool for rubber products is demonstrated. In this work, a commercial ethylene-propylene rubber, grafted with maleic anhydride, is thermo-reversibly cross-linked in two steps. The pending anhydride moieties are first modified with furfurylamine to graft furan groups to the rubber backbone. These pendant furan groups are then cross-linked with a bis-maleimide via a Diels-Alder coupling reaction. Both reactions can be performed under a broad range of experimental conditions and can easily be applied on a large scale. The material properties of the resulting Diels-Alder cross-linked rubbers are similar to a peroxide-cured ethylene/propylene/diene rubber (EPDM) reference. The cross-links break at elevated temperatures (> 150 °C) via the retro-Diels-Alder reaction and can be reformed by thermal annealing at lower temperatures (50-70 °C). Reversibility of the system was proven with infrared spectroscopy, solubility tests and mechanical properties. Recyclability of the material was also shown in a practical way, i.e., by cutting a cross-linked sample into small parts and compression molding them into new samples displaying comparable mechanical properties, which is not possible for conventionally cross-linked rubbers.

Ecology payoffs from red alder in southeast Alaska.

Treesearch

Sally Duncan

2004-01-01

Clearcutting has been the primary timber management practice in southeast Alaska forests since large-scale commercial forestry began in the 1950s. The dense, even-aged conifer stands that subsequently develop, however, may have undesirable consequences for some nontimber resources, most notably fish and wildlife.Red alder is frequently established in these...

Draft Genome sequence of Frankia sp. Strain QA3, a nitrogen-fixing actinobacterium isolated from the root nodule of Alnus nitida

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sen, Arnab; Beauchemin, Nicholas; Bruce, David

Members of actinomycete genus Frankia form a nitrogen-fixing symbiosis with 8 different families of actinorhizal plants. We report a high-quality draft genome sequence for Frankia sp. stain QA3, a nitrogen-fixing actinobacterium isolated from root nodules of Alnus nitida.

Late Quaternary vegetation and climate history of the central Bering land bridge from St. Michael Island, western Alaska

USGS Publications Warehouse

Ager, T.A.

2003-01-01

Pollen analysis of a sediment core from Zagoskin Lake on St. Michael Island, northeast Bering Sea, provides a history of vegetation and climate for the central Bering land bridge and adjacent western Alaska for the past ???30,000 14C yr B.P. During the late middle Wisconsin interstadial (???30,000-26,000 14C yr B.P.) vegetation was dominated by graminoid-herb tundra with willows (Salix) and minor dwarf birch (Betula nana) and Ericales. During the late Wisconsin glacial interval (26,000-15,000 14C yr B.P.) vegetation was graminoid-herb tundra with willows, but with fewer dwarf birch and Ericales, and more herb types associated with dry habitats and disturbed soils. Grasses (Poaceae) dominated during the peak of this glacial interval. Graminoid-herb tundra suggests that central Beringia had a cold, arid climate from ???30,000 to 15,000 14C yr B.P. Between 15,000 and 13,000 14C yr B.P., birch shrub-Ericales-sedge-moss tundra began to spread rapidly across the land bridge and Alaska. This major vegetation change suggests moister, warmer summer climates and deeper winter snows. A brief invasion of Populus (poplar, aspen) occurred ca. 11,000-9500 14C yr B.P., overlapping with the Younger Dryas interval of dry, cooler(?) climate. During the latest Wisconsin to middle Holocene the Bering land bridge was flooded by rising seas. Alder shrubs (Alnus crispa) colonized the St. Michael Island area ca. 8000 14C yr B.P. Boreal forests dominated by spruce (Picea) spread from interior Alaska into the eastern Norton Sound area in middle Holocene time, but have not spread as far west as St. Michael Island. ?? 2003 University of Washington. Published by Elsevier Inc. All rights reserved.

Tandem enyne metathesis-Diels-Alder reaction for construction of natural product frameworks.

PubMed

Rosillo, Marta; Domínguez, Gema; Casarrubios, Luis; Amador, Ulises; Pérez-Castells, Javier

2004-03-19

Enynes connected through aromatic rings are used as substrates for metathesis reactions. The reactivity of three ruthenium carbene complexes is compared. The resulting 1,3-dienes are suitable precursors of polycyclic structures via a Diels-Alder process. Some domino RCM-Diels-Alder reactions are performed, suggesting a possible beneficial effect of the ruthenium catalyst in the cycloaddition process. Other examples require Lewis acid cocatalyst. When applied to aromatic ynamines or enamines, a new synthesis of vinylindoles is achieved. Monitorization of several metathesis reactions with NMR shows the different behavior for ruthenium catalysts. New carbenic species are detected in some reactions with an important dependence on the solvent used.

Diels–Alder Exo-Selectivity in Terminal-Substituted Dienes and Dienophiles: Experimental Discoveries and Computational Explanations

PubMed Central

Lam, Yu-hong; Cheong, Paul Ha-Yeon; Mata, José M. Blasco; Stanway, Steven J.; Gouverneur, Véronique; Houk, K. N.

2009-01-01

The Diels–Alder reactions of a series of silyloxydienes and silylated dienes with acyclic α,β-unsaturated ketones and N-acyloxazolidinones have been investigated. The endo/exo stereochemical outcome is strongly influenced by the substitution pattern of the reactants. High exo selectivity was observed when the termini of the diene and the dienophile involved in the shorter forming bond are both substituted, while the normal endo preference was found otherwise. The exo-selective asymmetric Diels–Alder reactions using Evans’ oxazolidinone chiral auxiliary furnished a high level of π-facial selectivity in the same sense as their well-documented endo-selective counterparts. Computational results of these Diels–Alder reactions were consistent with the experimental endo/exo selectivity in most cases. A twist-asynchronous model accounts for the geometries and energies of the computed transition structures. PMID:19154113

Disease-mediated declines in N-fixation inputs by Alnus tenuifolia to early-successional floodplains in interior and south-central Alaska

Treesearch

R.W. Ruess; J.M. McFarland; L.M. Trummer; J.K. Rohrs-Richey

2009-01-01

Atmospheric nitrogen (N) fixation by Alnus tenuifolia can account for up to 70 percent of the N accumulated during vegetation development along river flood plains in interior Alaska. We assessed disease incidence and related mortality of a recent outbreak or fungal stem cankers on A. tenuifolia across three regions in Alaska...

Chemical and physical properties of two-year short-rotation deciduous species. [Olea sp. , Populus deltoides, Platanus sp. , Alnus glutinosa, Paulownia tomentosa, Robina pseudoacacia, Acer saccharinum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, C.S

1982-01-01

The following seven broadleaved species were tested: autumn olive (Olea sp.) eastern cottonwood (Populus deltoides), sycamore (Platanus species), black alder (Alnus glutinosa), royal paulownia (Paulownia tomentosa), black locust (Robina pseudoacacia) and silver maple (Acer saccharinum). The species and portions both significantly affected the chemical and the physical findings of the juvenile wood. The ages, which were tested in factorial combination with the species, also showed a significant effect on both the chemical and the physical properties of wood. All of the results indicated that both chemical and physical properties did vary with species, among the portions of the wood, andmore » according to the ages of the wood. From the portion standpoint, the bark had higher gross heat content, sulphur content, ash content and lignin content, and it was also higher in all three kinds of extractives contents. The wood portion was found to be rich in holocellulose, alpha-cellulose and pentosan. In considering the chemical and physical properties of juvenile wood among the species, eastern cottonwood was found to have the highest value for ash content and all of the three kinds of extractives content. Paulownia had the highest value for sulphur content. Black locust had highest gross heat content, holocellulose and alpha-cellulose contents. Silver maple had highest lignin content. Results from this study showed that these seven juvenile hardwood species can produce high biomass yields of fibre and energy when grown under intensive care in central and southern Illinois sites. The best species of these seven tested woods seem to be black locust, which could also serve as a raw material for the pulp and paper industry, as well as for a fuel for energy generation. However, further economic and energy efficiency analyses are needed before judging the feasibility of these short-rotation juvenile hardwood species.« less

The effect of limited availability of N or water on C allocation to fine roots and annual fine root turnover in Alnus incana and Salix viminalis.

PubMed

Rytter, Rose-Marie

2013-09-01

The effect of limited nitrogen (N) or water availability on fine root growth and turnover was examined in two deciduous species, Alnus incana L. and Salix viminalis L., grown under three different regimes: (i) supply of N and water in amounts which would not hamper growth, (ii) limited N supply and (iii) limited water supply. Plants were grown outdoors during three seasons in covered and buried lysimeters placed in a stand structure and filled with quartz sand. Computer-controlled irrigation and fertilization were supplied through drip tubes. Production and turnover of fine roots were estimated by combining minirhizotron observations and core sampling, or by sequential core sampling. Annual turnover rates of fine roots <1 mm (5-6 year(-1)) and 1-2 mm (0.9-2.8 year(-1)) were not affected by changes in N or water availability. Fine root production (<1 mm) differed between Alnus and Salix, and between treatments in Salix; i.e., absolute length and biomass production increased in the order: water limited < unlimited < N limited. Few treatment effects were detected for fine roots 1-2 mm. Proportionally more C was allocated to fine roots (≤2 mm) in N or water-limited Salix; 2.7 and 2.3 times the allocation to fine roots in the unlimited regime, respectively. Estimated input to soil organic carbon increased by ca. 20% at N limitation in Salix. However, future studies on fine root decomposition under various environmental conditions are required. Fine root growth responses to N or water limitation were less pronounced in Alnus, thus indicating species differences caused by N-fixing capacity and slower initial growth in Alnus, or higher fine root plasticity in Salix. A similar seasonal growth pattern across species and treatments suggested the influence of outer stimuli, such as temperature and light.

Tree Age Effects on Fine Root Biomass and Morphology over Chronosequences of Fagus sylvatica, Quercus robur and Alnus glutinosa Stands

PubMed Central

Jagodzinski, Andrzej M.; Ziółkowski, Jędrzej; Warnkowska, Aleksandra; Prais, Hubert

2016-01-01

There are few data on fine root biomass and morphology change in relation to stand age. Based on chronosequences for beech (9–140 years old), oak (11–140 years) and alder (4–76 years old) we aimed to examine how stand age affects fine root biomass and morphology. Soil cores from depths of 0–15 cm and 16–30 cm were used for the study. In contrast to previously published studies that suggested that maximum fine root biomass is reached at the canopy closure stage of stand development, we found almost linear increases of fine root biomass over stand age within the chronosequences. We did not observe any fine root biomass peak in the canopy closure stage. However, we found statistically significant increases of mean fine root biomass for the average individual tree in each chronosequence. Mean fine root biomass (0–30 cm) differed significantly among tree species chronosequences studied and was 4.32 Mg ha-1, 3.71 Mg ha-1 and 1.53 Mg ha-1, for beech, oak and alder stands, respectively. The highest fine root length, surface area, volume and number of fine root tips (0–30 cm soil depth), expressed on a stand area basis, occurred in beech stands, with medium values for oak stands and the lowest for alder stands. In the alder chronosequence all these values increased with stand age, in the beech chronosequence they decreased and in the oak chronosequence they increased until ca. 50 year old stands and then reached steady-state. Our study has proved statistically significant negative relationships between stand age and specific root length (SRL) in 0–30 cm soil depth for beech and oak chronosequences. Mean SRLs for each chronosequence were not significantly different among species for either soil depth studied. The results of this study indicate high fine root plasticity. Although only limited datasets are currently available, these data have provided valuable insight into fine root biomass and morphology of beech, oak and alder stands. PMID:26859755

Linking Landscape Characteristics and High Stream Nitrogen in the Oregon Coast Range: Red Alder Complicates Use of Nutrient Criteria

EPA Science Inventory

Red alder (a nitrogen-fixing tree) and sea salt inputs can strongly influence stream nitrogen concentrations in western Oregon and Washington. We compiled a database of stream nitrogen and landscape characteristics in the Oregon Coast Range. Basal area of alder, expressed as a ...

Herbivores and pathogens on Alnus viridis subsp. fruticosa in interior Alaska: effects of leaf, tree, and neighbour characteristics on damage levels

Treesearch

Christa P.H. Mulder; Bitty A. Roy; Sabine Gusewell

2008-01-01

Parasite damage strongly affects dynamics of boreal forests. Damage levels may be affected by climate change, either directly or indirectly through changes in properties of host trees. We examined how herbivore and pathogen damage in Alnus viridis subsp. fruticosa (Rupr.) Nym. depend on leaf morphology and chemistry, tree size...

Diversity-Oriented Approaches to Polycyclics and Bioinspired Molecules via the Diels-Alder Strategy: Green Chemistry, Synthetic Economy, and Beyond.

PubMed

Kotha, Sambasivarao; Chavan, Arjun S; Goyal, Deepti

2015-05-11

We describe diverse approaches to various dienes and their utilization in the Diels-Alder reaction to produce a variety of polycycles. The dienes covered here are prepared by simple alkylation reaction or via the Claisen rearrangement or by enyne metathesis of alkyne or enyne building blocks. Here, we have also included the Diels-Alder chemistry of dendralenes, a higher analog of cross-conjugated dienes. The present article is inclusive of o-xylylene derivatives that are generated in situ starting with benzosultine or benzosulfone derivatives. The Diels-Alder reaction of these dienes with various dienophiles gave diverse polycyclic systems and biologically important targets.

Widespread Expansion of Boreal Shrublands in the Siberian Low Arctic Is Linked to Cryogenic Disturbance and Geomorphology

NASA Astrophysics Data System (ADS)

Frost, G. V.; Epstein, H. E.; Walker, D. A.

2012-12-01

Declassified imagery from the KH-4B "Corona" and KH-7 "Gambit" Cold War satellite surveillance systems (1963-1972) are a unique, high-resolution dataset that establishes a baseline for landcover-change studies in the Russian Arctic spanning 6 decades. We co-registered Corona/Gambit and modern high-resolution imagery for seven ~65 km2 Low Arctic sites in northwest Siberia and Chukotka and quantified changes in the extent of tall shrublands dominated by Siberian alder (Alnus fruticosa) using a point-intercept sampling approach. We made ground observations at two sites to identify important geomorphic processes and physiographic units associated with shrub expansion. Alder shrubland cover increased at all sites; relative to the 1960s extent, shrubland extent increased by 5-31% at the northwest Siberian sites and by 9% at both Chukotkan sites,. In northwest Siberia, alder expansion was closely linked to cryogenic disturbances related to patterned-ground and active-layer detachments. At the Chukotkan sites, most alder expansion occurred on hillslope colluvium and floodplains; we also observed modest increases in Siberian dwarf pine (Pinus pumila). The close correspondence between expanding shrub patches and disturbance processes indicates that sparsely-vegetated, mineral-rich seedbeds strongly facilitate alder recruitment, and that the spatio-temporal attributes of disturbance mechanisms are a key determinant of landscape susceptibility to shrub expansion. Shrub expansion, in turn, initiates a cascade of effects on permafrost thermal regime and disturbance, promoting the accumulation of biomass and potentially buffering permafrost from climate warming.; Recently-established alder shrubs growing on non-sorted circles in patterned ground near Obskaya, northwest Siberia.

Chemical composition and deer browsing of red alder foliage

Treesearch

M.A. Radwan; W.D. Ellis; G.L. Crouch

1978-01-01

Chemical factors suspected of influencing seasonal change in deer preference for red alder leaves were investigated. There were many differences in the leaves between seasons. It is postulated, however, that changes in contents of crude fat and total phenols were the important factors in increasing deer preference for the species from June to September.

Retro iminonitroso Diels-Alder reactions: interconversion of nitroso cycloadducts

PubMed Central

Yang, Baiyuan; Lin, Weimin; Krchnak, Viktor; Miller, Marvin J.

2009-01-01

Retro iminonitroso Diels-Alder reactions were investigated in both solution and solid phase. In thermal or Cu(I)-mediated reactions, interconversion of various nitroso cycloadducts occurred in the presence of separate dienes. Up to 99% of conversion was observed. Use of chiral ligands in the Cu(I)-medicated reactions gave new cycloadducts enantioselectively. PMID:20161032

The effect of re-dissolution solvents and HPLC columns on the analysis of mycosporine-like amino acids in the eulittoral macroalgae Prasiola crispa and Porphyra umbilicalis

NASA Astrophysics Data System (ADS)

Karsten, Ulf; Escoubeyrou, Karine; Charles, François

2009-09-01

Many macroalgal species that are regularly exposed to high solar radiation such as the eulittoral green alga Prasiola crispa and the red alga Porphyra umbilicalis synthesize and accumulate high concentrations of mycosporine-like amino acids (MAAs) as UV-sunscreen compounds. These substances are typically extracted with a widely used standard protocol following quantification by various high performance liquid chromatography (HPLC) techniques. However, further preparation steps prior to HPLC analysis as well as different HPLC column types have not been systematically checked regarding separation quality and reproducibility. Therefore pure methanol, distilled water and HPLC eluent were evaluated as re-dissolution solvent for dried Prasiola and Porphyra extracts, which were subsequently analyzed on three reversed-phase C8 and C18 HPLC columns. The data indicate that distilled water and the HPLC eluent gave almost identical peak patterns and MAA contents on the C8 and C18 columns. In contrast, the application of the widely used methanol led to double peaks or even the loss of specific peaks as well as to a strong decline in total MAA amounts ranging from about 35% of the maximum in P. crispa to 80% of the maximum in P. umbilicalis. Consequently, methanol should be avoided as re-dissolution solvent for the HPLC sample preparation. An improved protocol for the MAA analysis in macroalgae in combination with a reliable C18 column is suggested.

Silica-promoted Diels-Alder reactions in carbon dioxide from gaseous to supercritical conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weinstein, R.D.; Renslo, A.R.; Danheiser, R.L.

1999-04-15

Amorphous fumed silica (SiO{sub 2}) was shown to increase yields and selectivities of several Diels-Alder reactions in gaseous and supercritical CO{sub 2}. Pressure effects on the Diels-Alder reaction were explored using methyl vinyl ketone and penta-1,3-diene at 80 C. The selectivity of the reaction was not affected by pressure/density. As pressure was increased, the yield decreased. At the reaction temperature, adsorption isotherms at various pressures were obtained for the reactants and the Diels-Alder adduct. As expected when pressure is increased, the ratio of the amount of reactants adsorbed to the amount of reactants in the fluid phase decreases, thus causingmore » the yield to decrease. The Langmuir adsorption model fit the adsorption data. The Langmuir equilibrium partitioning constants all decreased with increasing pressure. The effect of temperature on adsorption was experimentally determined and traditional heats of adsorption were calculated. However, since supercritical CO{sub 2} is a highly compressible fluid, it is logical to examine the effect of temperature at constant density. In this case, entropies of adsorption were obtained. The thermodynamic properties that influence the real enthalpy and entropy of adsorption were derived. Methods of doping the silica and improving yields and selectivities were also explored.« less

Structural Modification of Sol-Gel Materials through Retro Diels-Alder Reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

SHALTOUT,RAAFAT M.; LOY,DOUGLAS A.; MCCLAIN,MARK D.

1999-12-08

Hydrolysis and condensation of organically bridged bis-triethoxysilanes, (EtO){sub 3}Si-R-Si(OEt){sub 3}, results in the formation of three dimensional organic/inorganic hybrid networks (Equation 1). Properties of these materials, including porosity, are dependent on the nature of the bridging group, R. Flexible groups (akylene-spacers longer than five carbons in length) polymerize under acidic conditions to give non-porous materials. Rigid groups (such as arylene-, alkynylene-, or alkenylene) form non-porous, microporous, and macroporous gels. In many cases the pore size distributions are quite narrow. One of the motivations for preparing hybrid organic-inorganic materials is to extend the range of properties available with sol-gel systems bymore » incorporating organic groups into the inorganic network. For example, organically modified silica gels arc either prepared by co-polymerizing an organoalkoxysilane with a silica precursor or surface silylating the inorganic gel. This can serve to increase hydrophobicity or to introduce some reactive organic functionality. However, the type and orientation of these organic functionalities is difficult to control. Furthermore, many organoalkoxysilanes can act to inhibitor even prevent gelation, limiting the final density of organic functionalities. We have devised a new route for preparing highly functionalized pores in hybrid materials using bridging groups that are thermally converted into the desired functionalities after the gel has been obtained. In this paper, we present the preparation and characterization of bridged polysilsesquioxanes with Diels-Alder adducts as the bridging groups from the sol-gel polymerization of monomers 2 and 4. The bridging groups are constructed such that the retro Diela-Alder reaction releases the dienes and leaves the dienophiles as integral parts of the network polymers. In the rigid architecture of a xerogel, this loss of organic functionality should liberate sufficient space to

A new approach to the synthesis of monomers and polymers incorporating furan/maleimide Diels-Alder adducts

NASA Astrophysics Data System (ADS)

Banella, Maria Barbara; Gioia, Claudio; Vannini, Micaela; Colonna, Martino; Celli, Annamaria; Gandini, Alessandro

2016-05-01

The Diels-Alder reaction between furan and maleimide moieties is a well-known and widely used strategy to build bio-based macromolecular structures with peculiar properties. The furan-maleimide adducts are thermally reversible because they can be broken above about 120°C and recombined at lower temperatures. At the moment only the monomers exhibiting the furan or the maleimide moieties on their extremity are used in order to get linear or cross-linked polymeric structures. The innovative idea described here consists in using a monomer bearing two carboxylic acidic groups on its extremities and a furan-maleimide Diels-Alder adduct within its structure. This monomer can give rise to classical polycondensation reactions leading to polymers. These polymers (which are polyesters in the present case) can be broken at high temperatures in correspondence of the furane-maleimide Diels-Alder adduct leading to segments exhibiting furan or maleimide moieties at their extremities, which at lower temperature recombine leading to random or block copolymers.

Structural basis for Diels-Alder ribozyme-catalyzed carbon-carbon bond formation

PubMed Central

Serganov, Alexander; Keiper, Sonja; Malinina, Lucy; Tereshko, Valentina; Skripkin, Eugene; Höbartner, Claudia; Polonskaia, Anna; Phan, Anh Tuân; Wombacher, Richard; Micura, Ronald; Dauter, Zbigniew; Jäschke, Andres; Patel, Dinshaw J

2015-01-01

The majority of structural efforts addressing RNA’s catalytic function have focused on natural ribozymes, which catalyze phosphodiester transfer reactions. By contrast, little is known about how RNA catalyzes other types of chemical reactions. We report here the crystal structures of a ribozyme that catalyzes enantioselective carbon-carbon bond formation by the Diels-Alder reaction in the unbound state and in complex with a reaction product. The RNA adopts a λ-shaped nested pseudoknot architecture whose preformed hydrophobic pocket is precisely complementary in shape to the reaction product. RNA folding and product binding are dictated by extensive stacking and hydrogen bonding, whereas stereoselection is governed by the shape of the catalytic pocket. Catalysis is apparently achieved by a combination of proximity, complementarity and electronic effects. We observe structural parallels in the independently evolved catalytic pocket architectures for ribozyme- and antibody-catalyzed Diels-Alder carbon-carbon bond-forming reactions. PMID:15723077

Quantitative structure-activation barrier relationship modeling for Diels-Alder ligations utilizing quantum chemical structural descriptors.

PubMed

Nandi, Sisir; Monesi, Alessandro; Drgan, Viktor; Merzel, Franci; Novič, Marjana

2013-10-30

In the present study, we show the correlation of quantum chemical structural descriptors with the activation barriers of the Diels-Alder ligations. A set of 72 non-catalysed Diels-Alder reactions were subjected to quantitative structure-activation barrier relationship (QSABR) under the framework of theoretical quantum chemical descriptors calculated solely from the structures of diene and dienophile reactants. Experimental activation barrier data were obtained from literature. Descriptors were computed using Hartree-Fock theory using 6-31G(d) basis set as implemented in Gaussian 09 software. Variable selection and model development were carried out by stepwise multiple linear regression methodology. Predictive performance of the quantitative structure-activation barrier relationship (QSABR) model was assessed by training and test set concept and by calculating leave-one-out cross-validated Q2 and predictive R2 values. The QSABR model can explain and predict 86.5% and 80% of the variances, respectively, in the activation energy barrier training data. Alternatively, a neural network model based on back propagation of errors was developed to assess the nonlinearity of the sought correlations between theoretical descriptors and experimental reaction barriers. A reasonable predictability for the activation barrier of the test set reactions was obtained, which enabled an exploration and interpretation of the significant variables responsible for Diels-Alder interaction between dienes and dienophiles. Thus, studies in the direction of QSABR modelling that provide efficient and fast prediction of activation barriers of the Diels-Alder reactions turn out to be a meaningful alternative to transition state theory based computation.

The effect of pressure on microwave-enhanced Diels-Alder reactions. A case study.

PubMed

Kaval, Nadya; Dehaen, Wim; Kappe, C Oliver; Van der Eycken, Erik

2004-01-21

It is demonstrated that microwave-assisted Diels-Alder reactions of substituted 2(1H)-pyrazinones with ethylene are significantly more effective utilizing pre-pressurized (up to 10 bar) reaction vessels.

Enhancing the Scope of the Diels-Alder Reaction through Isonitrile Chemistry: Emergence of a New Class of Acyl-Activated Dienophiles

PubMed Central

Townsend, Steven D.; Wu, Xiangyang; Danishefsky, Samuel J.

2012-01-01

α,β-Unsaturated imides, formylated at the nitrogen atom, comprise a new and valuable family of dienophiles for servicing Diels-Alder reactions. These systems are assembled through extension of recently discovered isonitrile chemistry to the domain of α,β-unsaturated acids. Cycloadditions are facilitated by Et2AlCl, presumably via chelation between the two carbonyl groups of the N-formyl amide. Applications of the isonitrile/Diels-Alder logic to the IMDA reaction, as well as methodologies to modify the N-formyl amide of the resultant cycloaddition product, are described. It is expected that this easily executed chemistry will provide a significant enhancement for application of Diels-Alder reactions to many synthetic targets. PMID:22708980

Influence of flooding duration on the biomass growth of alder and willow.

Treesearch

Lewis F. Ohmann; M. Dean Knighton; Ronald McRoberts

1990-01-01

Simple second-order (quadratic) polynomials were used to model the relationship between 3-year biomass increase (net ovendry weight in grams) and flooding duration (days) for four combinations of shrub type (alder, willow) and soils type (fine-sand, clay-loam).

Enantioselective Diels-Alder reactions of unsaturated beta-ketoesters catalyzed by chiral ruthenium PNNP complexes.

PubMed

Schotes, Christoph; Mezzetti, Antonio

2011-01-01

We report here dicationic ruthenium PNNP complexes that promote the enantioselective Diels-Alder reaction of alpha-methylene beta-ketoesters with various dienes. Complex [Ru(OEt2)2(PNNP)](PF6)2, formed in situ from [RuCl2,(PNNP)] and (Et3O)PF6 (2 equiv.), catalyzes the Diels-Alder reaction of such unsaturated beta-ketoesters to give novel alkoxycarbonyltetrahydro-1-indanone derivatives (nine examples) with up to 93% ee. The crystal structure of the substrate-catalyst adduct shows that the lower face of the substrate is shielded by a phenyl ring of the PNNP ligand, which accounts for the high enantioselectivity. The attack of the diene from the open re enantioface of the unsaturated beta-ketoester is consistent with the absolute configuration of the product. A useful application of this method is the reaction with Dane's diene to give estrone derivatives with up to 99% ee and an ester-exo:endo ratio of up to 145:1 (after recrystallization). Besides the enantioselective formation of all-carbon quaternary centers, this methodology is notable because unsaturated beta-ketoesters have been rarely used in Diels-Alder reactions. Furthermore, enantiomerically pure estrone derivatives are interesting in view of their potential applications, including the treatment of breast cancer.

Biomass of Speckled Alder on an Air-Polluted Mountain Site and its Response to Fertilization

NASA Astrophysics Data System (ADS)

Kuneš, Ivan; Baláš, Martin; Koňasová, Tereza; Špulák, Ondřej; Balcar, Vratislav; Millerová, Kateřina Bednářová; Kacálek, Dušan; Jakl, Michal; Zahradník, Daniel; Vítámvás, Jan; Š´astná, Jaroslava; Jaklová Dytrtová, Jana

2014-12-01

The article summarizes outcomes of a biomass study conducted in a young speckled alder plantation on a cold mountain site. At this location, the previously existing old forest was clear felled because of damage from air pollution, and present-day surface humus is in need of restoration. The intention of this study was to quantify the biomass and nutrients accumulated by alders and their components and assess whether the initial fertilization resulted in increased biomass production and nutrient accumulation in the biomass. Besides the control, two fertilized treatments were installed. In the surface treatment (SUT), the amendment was applied as a base dressing in small circles around trees. In the planting-hole treatment (PHT), the amendment was incorporated into soil inside the planting holes. Five growth seasons after planting and fertilization, six alders from each treatment were harvested including roots. Their biomass was quantified and analyzed for macroelements. The greatest pool of dry mass (DM) was branches in the control and stem wood in the fertilized treatments. The greatest pools of macroelements were leaves and branches. The most pronounced effects of fertilization were recorded in the DM and consequently in the absolute quantities of nutrients. The DM of an average tree in the control, SUT, and PHT was 85, 226, and 231 g, respectively. The absolute contents of nutrients per tree in the fertilized treatments showed the following increases, as compared with the control: (N) 2.5-2.6 times; (P) 1.6-2.4 times; (K) 1.8-2.1 times; and (Mg) 1.8-2.0 times, respectively. Speckled alder responded positively to fertilization.

Watershed influences on the structure and function of riparian wetlands associated with headwater streams - Kenai Peninsula, Alaska.

PubMed

Whigham, D F; Walker, C M; Maurer, J; King, R S; Hauser, W; Baird, S; Keuskamp, J A; Neale, P J

2017-12-01

Riparian wetlands are dynamic components of landscapes. Located between uplands and aquatic environments, riparian habitats intercept sediments and nutrients before they enter aquatic environments. They are a source of organic matter and nutrients to aquatic systems, and they provide important habitat for animals, often serving as corridors for the movement of animals between habitats in fragmented landscapes. In this project, we focused on the structure and function of riparian wetlands associated with headwater streams in Alaska that serve as nursery habitats for juvenile salmonids. We asked whether or not the structure and function of headwater wetlands differed between watersheds with and without nitrogen-fixing Alder (Alnus spp.). We found that the aboveground biomass of riparian vegetation was higher in the watershed with Alder, but the largest differences were in the litter layer and belowground where vegetation in the watershed with no Alder had significantly higher root biomass. Interstitial water chemistry also differed between the study sites with significantly higher inorganic N and significantly different characteristics of colored dissolved organic matter at the site with Alder on the watershed. The biomass of litter that hung over the creek bank was less at the site with Alder on the watershed and an in situ decomposition experiment showed significant differences between the two systems. Results of the research demonstrates that watershed characteristics can impact the ecology of headwater streams in ways that had not been previously recognized. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

Neuroanatomy of Halobiotus crispae (Eutardigrada: Hypsibiidae): Tardigrade brain structure supports the clade Panarthropoda.

PubMed

Persson, Dennis K; Halberg, Kenneth A; Jørgensen, Aslak; Møbjerg, Nadja; Kristensen, Reinhardt M

2012-11-01

The position of Tardigrada in the animal tree of life is a subject that has received much attention, but still remains controversial. Whereas some think tardigrades should be categorized as cycloneuralians, most authors argue in favor of a phylogenetic position within Panarthropoda as a sister group to Arthropoda or Arthropoda + Onychophora. Thus far, neither molecular nor morphological investigations have provided conclusive results as to the tardigrade sister group relationships. In this article, we present a detailed description of the nervous system of the eutardigrade Halobiotus crispae, using immunostainings, confocal laser scanning microscopy, and computer-aided three-dimensional reconstructions supported by transmission electron microscopy. We report details regarding the structure of the brain as well as the ganglia of the ventral nerve cord. In contrast to the newest investigation, we find transverse commissures in the ventral ganglia, and our data suggest that the brain is partitioned into at least three lobes. Additionally, we can confirm the existence of a subpharyngeal ganglion previously called subesophagal ganglion. According to our results, the original suggestion of a brain comprised of at least three parts cannot be rejected, and the data presented supports a sister group relationship of Tardigrada to 1) Arthropoda or 2) Onychophora or 3) Arthropoda + Onychophora. Copyright © 2012 Wiley Periodicals, Inc.

A microwave assisted intramolecular-furan-Diels-Alder approach to 4-substituted indoles.

PubMed

Petronijevic, Filip; Timmons, Cody; Cuzzupe, Anthony; Wipf, Peter

2009-01-07

The key steps of a versatile new protocol for the convergent synthesis of 3,4-disubstituted indoles are the addition of an alpha-lithiated alkylaminofuran to a carbonyl compound, a microwave-accelerated intramolecular Diels-Alder cycloaddition and an in situ double aromatization reaction.

Diversity of Frankia populations in root nodules of geographically isolated Arizona alder trees in central Arizona (United States)

Treesearch

Allana K. Welsh; Jeffrey O. Dawson; Gerald J. Gottfried; Dittmar Hahn

2009-01-01

The diversity of uncultured Frankia populations in root nodules of Alnus oblongifolia trees geographically isolated on mountaintops of central Arizona was analyzed by comparative sequence analyses of nifH gene fragments. Sequences were retrieved from Frankia populations in nodules of four trees from each of...

61. Photocopy of Engine Room Floor Plan, White Alder. The ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

61. Photocopy of Engine Room Floor Plan, White Alder. The Niagara Shipbuilding Corp. Engineering Department, Buffalo, New York. Coast Guard Headquarters Drawing No. 540-WAGL-1604-10, dated February 1943; revised January 1963. Original drawing property of the U.S. Coast Guard. - U.S. Coast Guard Cutter WHITE HEATH, USGS Integrated Support Command Boston, 427 Commercial Street, Boston, Suffolk County, MA

A microwave assisted intramolecular-furan-Diels–Alder approach to 4-substituted indoles†

PubMed Central

Petronijevic, Filip; Timmons, Cody; Cuzzupe, Anthony; Wipf, Peter

2009-01-01

The key steps of a versatile new protocol for the convergent synthesis of 3,4-disubstituted indoles are the addition of an α-lithiated alkylaminofuran to a carbonyl compound, a microwave-accelerated intramolecular Diels–Alder cycloaddition and an in situ double aromatization reaction. PMID:19082013

The ectomycorrhizas of Lactarius cuspidoaurantiacus and Lactarius herrerae associated with Alnus acuminata in Central Mexico.

PubMed

Montoya, Leticia; Bandala, Victor M; Garay-Serrano, Edith

2015-08-01

Two pure Alnus acuminata stands established in a montane forest in central Mexico (Puebla State) were monitored between 2010 and 2013 to confirm and recognize the ectomycorrhizal (EcM) systems of A. acuminata with Lactarius cuspidoaurantiacus and Lactarius herrerae, two recently described species. Through comparison of internal transcribed spacer (ITS) of nuclear ribosomal DNA sequences from basidiomes and ectomycorrhizas sampled in the forest stands, we confirmed their ectomycorrhizal association. The phytobiont was corroborated by comparing ITS sequences obtained from EcM root tips and leaves collected in the study site and from other sequences of A. acuminata available in Genbank. Detailed morphological and anatomical descriptions of the ectomycorrhizal systems are presented and complemented with photographs.

Regiocontrol by remote substituents. An enantioselective total synthesis of frenolicin B via a highly regioselective Diels-Alder reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kraus, G.A.; Li, J.; Gordon, M.S.

1993-06-30

The quinone subunit is contained in a broad range of biologically important natural products such as frenolicin B, which is a member of the pyranonaphthoquinone family. The diverse biological activity of quinones has led to the development of several new synthetic methods for quinones. Among the pathways featuring a cycloaddition reaction, one of the most general methods for the regiospecific synthesis of substituted quinones was pioneered by H.J. Rapoport and others. This method involves the Diels-Alder reaction of a substituted quinone. As part of a program to evaluate the directing effects of functional groups not directly attached to the atomsmore » undergoing Diels-Alder cycloaddition, we now report that remote substituents on a dienophile can confer excellent regioselectivity in Diels-Alder reactions. This work has led to an extremely direct synthesis of the pyranonaphthoquinone framework and to the first synthesis of frenolicin B (1). 19 refs., 1 fig.« less

Inhibition of the growth of Alexandrium tamarense by algicidal substances in Chinese fir (Cunninghamia lanceolata).

PubMed

Yang, Wei-Dong; Liu, Jie-Sheng; Li, Hong-Ye; Zhang, Xin-Lian; Qi, Yu-Zao

2009-10-01

The wood sawdust from Chinese fir (Cunninghamia lanceolata) exhibited stronger inhibition on the growth of Alexandrium tamarense than those from alder (Alnus cremastogyne), pine (Pinus massoniana), birch (Betula alnoides) and sapele (Entandrophragma cylindricum). The water extract, acetone-water extract and essential oil from fir sawdust were all shown to inhibit the growth of A. tamarense. The inhibition of fir essential oil was the strongest among all the above wood sources while the half effective concentration was only 0.65 mg/L. These results suggested that the fir essential oil may play an important role in the algicidal effect of Chinese fir.

Do Invertebrate Activity and Current Velocity Affect Fungal Assemblage Structure in Leaves?

NASA Astrophysics Data System (ADS)

Ferreira, Verónica; Graça, Manuel A. S.

2006-02-01

In this study we assessed the effect of current velocity and shredder presence, manipulated in artificial channels, on the structure of the fungal assemblage colonizing alder (Alnus glutinosa (L.) Gaertner) leaves incubated in coarse and fine mesh bags. Fungal sporulation rates, cumulative conidial production and number of species of aquatic hyphomycetes were higher in leaves exposed to high rather than to low current velocity. The opposite was observed regarding Simpson's index (D) on the fungal assemblage. Some species of aquatic hyphomycetes were consistently stimulated in high current channels. No effect of shredders or of mesh type was observed.

Time and distance to clear wood in pruned red alder saplings.

Treesearch

Dean S. DeBell; Constance A. Harrington; Barbara L. Gartner; Ryan. Singleton

2006-01-01

Pruning trials in young alder stands were sampled to evaluate response to pruning. Effects of pruning (1) live branches on different dates, and (2) dead branches with or without damaging the branch collar were assessed on trees pruned in 3- and 6-year-old plantations, respectively. Six years after pruning, stem sections were collected and dissected in the longitudinal-...

The reliability of determining age of red alder by ring counts

Treesearch

Dean S. DeBell; Boyd C. Wilson; Bernard T. Bormann

1978-01-01

Examination of cross-sections of 54 red alder trees from 14 stands of varying age and site conditions indicated that abnormal rings (false, partial, or missing) occur infrequently. Rings may be indistinct and ring counting must be done with great care, preferably on prepared surfaces (cross-sections or cores) and under magnification and good lighting. With such...

Nitropyrroles, Diels-Alder reactions assisted by microwave irradiation and solvent effect. An experimental and theoretical study

NASA Astrophysics Data System (ADS)

Mancini, Pedro M. E.; Kneeteman, María N.; Cainelli, Mauro; Ormachea, Carla M.; Domingo, Luis R.

2017-11-01

The behaviors of N-tosylnitropyrroles acting as electrophilic dienophiles in polar Diels-Alder reactions joint to different dienes of increeased nucleophilicity are analyzed. The reactions were developed under microwave irradiation using toluene or protic ionic liquids (PILs) as solvents and in free solvent conditions. In all the cases explored we observed good yields in short reaction times. For these reactions, the free solvent condition and the use of protic ionic liquids as solvents offer similar results. However, the free solvent conditions favor environmental sustainability. The role of PILs in these polar Diels-Alder reactions has been theoretically studied within the Molecular Electron Density Theory.

Comparison of terrestrial invertebrate biomass and richness in young mixed red alder-conifer, young conifer, and old conifer stands of southeast Alaska.

Treesearch

Mark E. Schultz; Toni L. De Santo

2008-01-01

Coniferous stands that regenerate following clearcutting in southeast Alaska can be characterized by the amount of soil disturbance during logging. There are indications that red alder in mixed stands mitigates some of the negative effects of clearcutting. We compared invertebrate biomass in four stands each of (1) young conifers, (2) young mixed alder and conifer, and...

Patterned-ground facilitates shrub expansion in Low Arctic tundra

NASA Astrophysics Data System (ADS)

Frost, Gerald V.; Epstein, Howard E.; Walker, Donald A.; Matyshak, Georgiy; Ermokhina, Ksenia

2013-03-01

Recent expansion of tall shrubs in Low Arctic tundra is widely seen as a response to climate warming, but shrubification is not occurring as a simple function of regional climate trends. We show that establishment of tall alder (Alnus) is strongly facilitated by small, widely distributed cryogenic disturbances associated with patterned-ground landscapes. We identified expanding and newly established shrub stands at two northwest Siberian sites and observed that virtually all new shrubs occurred on bare microsites (‘circles’) that were disturbed by frost-heave. Frost-heave associated with circles is a widespread, annual phenomenon that maintains mosaics of mineral seedbeds with warm soils and few competitors that are immediately available to shrubs during favorable climatic periods. Circle facilitation of alder recruitment also plausibly explains the development of shrublands in which alders are regularly spaced. We conclude that alder abundance and extent have increased rapidly in the northwest Siberian Low Arctic since at least the mid-20th century, despite a lack of summer warming in recent decades. Our results are consistent with findings in the North American Arctic which emphasize that the responsiveness of Low Arctic landscapes to climate change is largely determined by the frequency and extent of disturbance processes that create mineral-rich seedbeds favorable for tall shrub recruitment. Northwest Siberia has high potential for continued expansion of tall shrubs and concomitant changes to ecosystem function, due to the widespread distribution of patterned-ground landscapes.

Polar Diels-Alder reactions using electrophilic nitrobenzothiophenes. A combined experimental and DFT study

NASA Astrophysics Data System (ADS)

Della Rosa, Claudia D.; Mancini, Pedro M. E.; Kneeteman, Maria N.; Lopez Baena, Anna F.; Suligoy, Melisa A.; Domingo, Luis R.

2015-01-01

The reactions between 2- and 3-nitrobenzothiophenes with three dienes of different nucleophilicity, 1-methoxy-3-trimethylsilyloxy-1,3-butadiene, 1-trimethylsilyloxy-1,3-butadiene and isoprene developed in anhydrous benzene and alternative under microwave irradiation with molecular solvents or in free solvent conditions, respectively, for produce dibenzothiophenes permit to conclude that both nitroheterocycles act as electrophile with the cited dienes. In the cases of the dienes 1-methoxy-3-trimethylsilyloxy-1,3-butadiene and 1-trimethylsilyloxy-1,3-butadiene which posses major nucleophilicity the observed product is the normal cycloaddition one. However when the diene is isoprene the product with both electrophiles follow the hetero Diels-Alder way. These reactions are considered polar cycloaddition reactions and the yields are reasonables. Moreover the polar Diels-Alder reactions of nitrobenzothiophenes with electron rich dienes 1-trimethylsilyloxy-1,3-butadiene have been theoretically studied using DFT methods.

Postglacial vegetation history of Mitkof Island, Alexander Archipelago, southeastern Alaska

USGS Publications Warehouse

Ager, T.A.; Carrara, P.E.; Smith, Jane L.; Anne, V.; Johnson, J.

2010-01-01

An AMS radiocarbon-dated pollen record from a peat deposit on Mitkof Island, southeastern Alaska provides a vegetation history spanning ∼12,900 cal yr BP to the present. Late Wisconsin glaciers covered the entire island; deglaciation occurred > 15,400 cal yr BP. The earliest known vegetation to develop on the island (∼12,900 cal yr BP) was pine woodland (Pinus contorta) with alder (Alnus), sedges (Cyperaceae) and ferns (Polypodiaceae type). By ∼12,240 cal yr BP, Sitka spruce (Picea sitchensis) began to colonize the island while pine woodland declined. By ∼11,200 cal yr BP, mountain hemlock (Tsuga mertensiana) began to spread across the island. Sitka spruce-mountain hemlock forests dominated the lowland landscapes of the island until ∼10,180 cal yr BP, when western hemlock (Tsuga heterophylla) began to colonize, and soon became the dominant tree species. Rising percentages of pine, sedge, and sphagnum after ∼7100 cal yr BP may reflect an expansion of peat bog habitats as regional climate began to shift to cooler, wetter conditions. A decline in alders at that time suggests that coastal forests had spread into the island's uplands, replacing large areas of alder thickets. Cedars (Chamaecyparis nootkatensis, Thuja plicata) appeared on Mitkof Island during the late Holocene.

Postglacial vegetation history of Mitkof Island, Alexander Archipelago, southeastern Alaska

NASA Astrophysics Data System (ADS)

Ager, Thomas A.; Carrara, Paul E.; Smith, Jane L.; Anne, Victoria; Johnson, Joni

2010-03-01

An AMS radiocarbon-dated pollen record from a peat deposit on Mitkof Island, southeastern Alaska provides a vegetation history spanning ˜12,900 cal yr BP to the present. Late Wisconsin glaciers covered the entire island; deglaciation occurred > 15,400 cal yr BP. The earliest known vegetation to develop on the island (˜12,900 cal yr BP) was pine woodland ( Pinus contorta) with alder ( Alnus), sedges (Cyperaceae) and ferns (Polypodiaceae type). By ˜12,240 cal yr BP, Sitka spruce ( Picea sitchensis) began to colonize the island while pine woodland declined. By ˜11,200 cal yr BP, mountain hemlock ( Tsuga mertensiana) began to spread across the island. Sitka spruce-mountain hemlock forests dominated the lowland landscapes of the island until ˜10,180 cal yr BP, when western hemlock ( Tsuga heterophylla) began to colonize, and soon became the dominant tree species. Rising percentages of pine, sedge, and sphagnum after ˜7100 cal yr BP may reflect an expansion of peat bog habitats as regional climate began to shift to cooler, wetter conditions. A decline in alders at that time suggests that coastal forests had spread into the island's uplands, replacing large areas of alder thickets. Cedars ( Chamaecyparis nootkatensis, Thuja plicata) appeared on Mitkof Island during the late Holocene.

The role of aqueous leaf extract of Tinospora crispa as reducing and capping agents for synthesis of gold nanoparticles

NASA Astrophysics Data System (ADS)

Apriandanu, D. O. B.; Yulizar, Y.

2017-04-01

Environmentally friendly method for green synthesis of Au nanoparticles (AuNP) using aqueous leaf extract of Tinospora crispa (TLE) was reported. TLE has the ability for reducing and capping AuNP. Identification of active compounds in aqueous leaf extract was obtained by phytochemical analysis and Fourier transform infrared spectroscopy (FTIR). The AuNP-TLE growth was characterized using UV-Vis spectrophotometer. The particle size and the distribution of AuNP were confirmed by particle size analyzer (PSA). AuNP-TLE formation was optimized by varying the extract concentration and time of the synthesis process. UV-Vis absorption spectrum of optimum AuNP formation displayed by the surface plasmon resonance at maximum wavelength of λmax 536 nm. The PSA result showed that AuNP has size distribution of 80.60 nm and stable up to 21 days. TEM images showed that the size of the AuNP is ± 25 nm.

Origins of Stereoselectivity in Diels-Alder Cycloadditions Catalyzed by Chiral Imidazolidinones

PubMed Central

Gordillo, Ruth; Houk, K. N.

2011-01-01

B3LYP/6-31G(d) density functional theory has been used to study Diels-Alder reactions of cyclopentadiene with α,β-unsaturated aldehydes and ketones organocatalyzed by MacMillan’s chiral imidazolidinones. Preferred conformations of transition structures and reaction intermediates have been located. The dramatically different reactivities and enantioselectivities exhibited by two similar chiral imidazolidinones are rationalized. PMID:16536527

Enzymatic activity and partial purification of solanapyrone synthase: first enzyme catalyzing Diels-Alder reaction.

PubMed

Katayama, K; Kobayashi, T; Oikawa, H; Honma, M; Ichihara, A

1998-05-19

In cell-free extracts of Alternaria solani, an enzymatic activity converting prosolanapyrone II to solanapyrones A and D via oxidation and subsequent Diels-Alder reaction has been found. Chromatography with DEAE-Sepharose provided two active fractions, pools 1 and 2. The former fraction converted prosolanapyrone II to solanapyrones A and D in a ratio of 2.2:1 with optical purities of 99% and 45% ee, respectively. The latter fraction did so in a ratio of 7.6:1 with 99% and nearly 0% ee, respectively. The enzyme partially purified from pool 2 native molecular weight of 40-62 kD and a pl of 4.25. The high reactivity of prosolanapyrone III in aqueous solution and the chromatographic behavior of the enzyme in pool 2 suggest that a single enzyme catalyzes both the oxidation and Diels-Alder reaction.

Landscape heterogeneity controls growth variability of alder, willow, and birch shrubs in response to observed increases in temperature and snow

NASA Astrophysics Data System (ADS)

Tape, K. D.; Hallinger, M.; Buras, A.; Wilmking, M.

2013-12-01

Over the last decade, evidence has emerged for a circumarctic trend of increasing shrub cover in tundra regions. On the Alaskan tundra, repeat photography has shown spatial differences in shrub patch dynamics: since 1950, most patches expanded while some remained stable. In this study we explore the underpinnings of this landscape heterogeneity by sampling the three dominant shrubs of the Alaskan tundra--alder, willow and birch--and creating shrub ring width chronologies to determine the influence of climate variability on shrub growth. Shrubs of expanding patches of all three species grew at higher rates than shrubs of stable patches. Alder and willow shrubs in expanding patches exhibited mainly positive growth trends, while their counterparts in stable patches exhibited mainly negative growth trends. Birch shrub growth declined in expanding and stable patches. Alder and willow shrub growth rates and responses to climate were controlled more by soil characteristics than by their genus; expanding alder and willow shrubs showed significant positive correlations with spring and summer temperatures, whereas alder and willow shrubs of stable patches were negatively influenced by winter precipitation. The widely-scattered stable shrub patches sampled here are considered ';moist tussock tundra,' which covers 13.4% of the low arctic landscape. In moist tussock tundra, and presumably also wet tussock tundra, the negative influence of deeper snow on shrubs outweighed the positive influence of deeper snow on ground temperature and nutrient stocks articulated by the snow-shrub-microbe hypothesis. Thus, while shrubs of expanding patches have generally profited from warmer summers, shrubs of stable patches have suffered from increased soil moisture resulting from increased snowmelt water. These results underscore the spatial and temporal complexity in shrub-climate dynamics, which will require considerable finesse to appropriately integrate into modeling efforts.

Diels-Alder reactions onto fluorinated and hydrogenated graphene

NASA Astrophysics Data System (ADS)

Denis, Pablo A.

2017-09-01

We studied Diels-Alder (DA) reactions onto functionalized graphene. When fluorine, hydrogen or oxygen functional groups are present on one side of the sheet, the DA cycloadditions become significantly more exergonic when performed on the opposite side. Hydrogen is more effective than fluorine and oxygen to promote these cycloadditions. In contrast with the results obtained for perfect graphene, the functionalization with H, F or O turns the DA reactions exergonic, with ΔG°298 = -127.2 kcal/mol. The reaction barriers are expected to be considerably lowered with respect to perfect graphene because the functional groups significantly reduce the distortion energy.

Assembly of the Isoindolinone Core of Muironolide A by Asymmetric Intramolecular Diels-Alder Cycloaddition

PubMed Central

Flores, Beatris; Molinski, Tadeusz F.

2011-01-01

The hexahydro-1H-isoindolin-1-one core of muironolide A was prepared by asymmetric intramolecular Diels Alder cycloaddition using a variant of the MacMillan organocatalyst which sets the C4,C5 and C11 stereocenters. PMID:21751773

Synthesis of isochromene-type scaffolds via single-flask Diels-Alder-[4 + 2]-annulation sequence of a silyl-substituted diene with menadione.

PubMed

Lee, Jihoon; Panek, James S

2014-06-20

A sequential Diels-Alder reaction/silicon-directed [4 + 2]-annulation was developed to assemble hydroisochromene-type ring systems from menadione 2. In the first step, a Diels-Alder of the 1-silyl-substituted butadiene 1 with 2 furnished an intermediate cyclic allylsilane. Subsequently, TMSOTf promoted a [4 + 2]-annulation through trapping of an oxonium, generated by condensation between an aldehyde and the TBS protected alcohol resulted in the formation of a cis-fused hydroisochromene 13.

The antidiabetic effects of an herbal formula composed of Alnus hirsuta, Rosa davurica, Acanthopanax senticosus and Panax schinseng in the streptozotocin-induced diabetic rats.

PubMed

Hu, Weicheng; Yeo, Jin-Hee; Jiang, Yunyao; Heo, Seong-Il; Wang, Myeong-Hyeon

2013-04-01

A folk prescription consisting of Alnus hirsuta, Rosa davurica, Acanthopanax senticosus and Panax schinseng has been used in the treatment of diabetes mellitus. The aim of the present investigation was to evaluate the antidiabetic effects of the herb formula extract (HFE) composed of Alnus hirsuta, Rosa davurica, Acanthopanax senticosus and Panax schinseng in the streptozotocin (STZ)-induced diabetic rats. The HFE was mixed in the food supply of the healthy and STZ-induced diabetic male Sprague-Dawley rats, and its effects on the body weight, water and food intake, hyperglycemia, hypolipidemic and islet structure were studied. The treatment of the rats with STZ for 6 weeks resulted in marasmus, polydipsia, polyphagia, hyperglycemia and hypoinsulinemia. In addition, the diabetic rats showed an apparent decrease in the insulin immunoreactivity and the number of β-cells in the pancreas. The addition of the HFE to the rats' food supply significantly lowered the serum glucose and the serum triglycerides level and preserved the normal histological appearance of the pancreatic islets. These results indicate that the HEF have a strong antidiabetic potential along with the significant hypoglycemic and hypolipidemic effects, which may be applicable in the pharmaceutical industry.

Aqueous catalysis: Methylrhenium trioxide (MTO) as a homogeneous catalyst for the Diels-Alder reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Z.; Espenson, J.H.

1997-04-16

The title compound proves to be an effective and efficient catalyst for the Diels-Alder reaction when the dienophile is an {alpha},{beta}-unsaturated ketone or aldehyde. It is especially effective in water. Equal amounts of any such dienophile and any of six representative dienes (isoprene, 2-methyl-1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, cyclopentadiene, 1,2,3,4,5,-pentamethylcyclopentadiene, and 1,3-cyclohexadiene) were used, along with 1% MTO. The reactions gave usually > 90% isolated yield of the cycloaddition product except for the larger dienophiles. Nearly exclusively, there was formed one product isomer, the same one that usually predominates. The reactions were often run in chloroform (mostly) and in other organic solvents. Amore » select number were carried out in water, where the reactions gave a greater product yield in a considerably shorter time. Water, itself, is known to enhance the rates of Diels-Alder reactions, but MTO exerts an additional accelerating effect. Kinetics studies were carried out to show that the rate is proportional to the catalyst concentration. The products do not inhibit the reaction. The desirability of MTO as a Diels-Alder catalyst stems from a combination of favorable properties: the inertness to air/oxygen, the tolerance for many substrates, the use of an aqueous medium, and the absence of product inhibition. The initial step appears to be the (weak) coordination of the carbonyl oxygen to the electropositive rhenium center. Steric crowding around rhenium inhibits reactions of the larger dienophiles. 26 refs., 3 figs., 4 tabs.« less

Recent and Holocene Climate Change Controls on Vegetation and Carbon Accumulation in Alaskan Coastal Muskegs

NASA Technical Reports Server (NTRS)

Peteet, Dorothy M.; Nichols, Jonathan E.; Moy, Christopher M.; McGeachy, Alicia; Perez, Max

2015-01-01

Pollen, spore, macrofossil and carbon data from a peatland near Cordova, Alaska, reveal insights into the climate-vegetation-carbon interactions from the initiation of the Holocene, c. the last 11.5 ka, to the present (1 ka = 1000 calibrated years before present where 0 = 1950 CE). The Holocene period is characterized by early deposition of gyttja in a pond environment with aquatics such as Nuphar polysepalum and Potamogeton, and a significant regional presence of Alnus crispa subsp. sinuata. Carbon accumulation (50 g/m2/a) was high for a short interval in the early Holocene when Sphagnum peat accumulated, but was followed by a major decline to 13 g/m2/a from 7 to 3.7 ka when Cyperaceae and ericads such as Rhododendron (formerly Ledum) groenlandicum expanded. This shift to sedge growth is representative of many peatlands throughout the south-central region of Alaska, and indicates a drier, more evaporative environment with a large decline in carbon storage. The subsequent return to Sphagnum peat after 4 ka in the Neoglacial represents a widespread shift to moister, cooler conditions, which favored a resurgence of ericads, such as Andromeda polifolia, and increased carbon accumulation rate. The sustained Alnus expansion visible in the top 10 cm of the peat profile is correlative with glacial retreat and warming of the region in the last century, and suggests this colonization will continue as temperature increases and ice melts.

Indole synthesis by palladium-catalyzed tandem allylic isomerization - furan Diels-Alder reaction.

PubMed

Xu, Jie; Wipf, Peter

2017-08-30

A Pd(0)-catalyzed elimination of an allylic acetate generates a π-allyl complex that is postulated to initiate a novel intramolecular Diels-Alder cycloaddition to a tethered furan (IMDAF). Under the reaction conditions, this convergent, microwave-accelerated cascade process provides substituted indoles in moderate to good yields after Pd-hydride elimination, aromatization by dehydration, and in situ N-Boc cleavage.

Ring-rearrangement metathesis of nitroso Diels-Alder cycloadducts.

PubMed

Vincent, Guillaume; Kouklovsky, Cyrille

2011-03-01

Strained nitroso Diels-Alder bicyclo[2.2.1] or [2.2.2] adducts functionalized with alkene side chains of diverse length undergo a ring-rearrangement metathesis process with external alkenes and Grubbs II or Hoveyda-Grubbs II ruthenium catalysts, under microwave irradiation or classical heating, to deliver cis-fused bicycles of various ring sizes, which contain a N-O bond. These scaffolds are of synthetic relevance for the generation of molecular diversity and to the total synthesis of alkaloids. The observation of unexpected reactions, such as epimerization or one-carbon homologation of the alkene side chain, is also reported. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A computational study of the Diels-Alder reactions between 2,3-dibromo-1,3-butadiene and maleic anhydride

NASA Astrophysics Data System (ADS)

Rivero, Uxía; Meuwly, Markus; Willitsch, Stefan

2017-09-01

The neutral and cationic Diels-Alder-type reactions between 2,3-dibromo-1,3-butadiene and maleic anhydride have been computationally explored as the first step of a combined experimental and theoretical study. Density functional theory calculations show that the neutral reaction is concerted while the cationic reaction can be either concerted or stepwise. Further isomerizations of the Diels-Alder products have been studied in order to predict possible fragmentation pathways in gas-phase experiments. Rice-Ramsperger-Kassel-Marcus (RRKM) calculations suggest that under single-collision experimental conditions the neutral product may reform the reactants and the cationic product will most likely eliminate CO2.

Synthesis of 3,4-dihydro-1,8-naphthyridin-2(1H)-ones via microwave-activated inverse electron-demand Diels-Alder reactions.

PubMed

Fadel, Salah; Hajbi, Youssef; Khouili, Mostafa; Lazar, Said; Suzenet, Franck; Guillaumet, Gérald

2014-01-01

Substituted 3,4-dihydro-1,8-naphthyridin-2(1H)-ones have been synthesized with the inverse electron-demand Diels-Alder reaction from 1,2,4-triazines bearing an acylamino group with a terminal alkyne side chain. Alkynes were first subjected to the Sonogashira cross-coupling reaction with aryl halides, the product of which then underwent an intramolecular inverse electron-demand Diels-Alder reaction to yield 5-aryl-3,4-dihydro-1,8-naphthyridin-2(1H)-ones by an efficient synthetic route.

Leaf litter dynamics and nitrous oxide emission in a Mediterranean riparian forest: implications for soil nitrogen dynamics.

PubMed

Bernal, S; Butturini, A; Nin, E; Sabater, F; Sabater, S

2003-01-01

Mediterranean riparian zones can experience severe drought periods that lead to low soil moisture content, which dramatically affects their performance as nitrate removal systems. In the Mediterranean riparian zone of this study, we determined that N2O emission was practically nil. To understand the role of forest floor processes in nitrogen retention of a Mediterranean riparian area, we studied leaf litter dynamics of two tree species, London planetree [Platanus x acerifolia (Aiton) Willd.] and alder [Alnus glutinosa (L.) Gaertn.], for two years, along with soil nitrogen mineralization rates. Annual leaf litter fall equaled 562.6 +/- 10.1 (standard error) g dry wt. m(-2), 68% of which was planetree and 32% of which was alder. The temporal distribution of litterfall showed a two-peak annual cycle, one occurring in midsummer, the other in autumn. Planetree provided the major input of organic nitrogen to the forest floor, and the amount of planetree leaves remaining on the forest floor was equivalent to approximately four years of stock. Leaf litter decomposition was three times higher for alder (decay coefficient [k] = 1.13 yr(-1)) than for planetree (k = 0.365 yr(-1)). Mineralization rates showed a seasonal pattern, with the maximum rate in summer (1.92 mg N kg(-1) d(-1)). Although the forest floor was an important sink for nitrogen due to planetree leaf accumulation, 7.5% of this leaf litter was scoured to the streambed by wind. This loss was irrelevant for alder leaves. Due to the litter quality, the forest floor of this Mediterranean riparian forest acts as a nitrogen sink.

Grazing preference and utilization of soil fungi by Folsomia candida (Collembola)

NASA Astrophysics Data System (ADS)

Hedenec, Petr; Frouz, Jan

2016-04-01

Soil fungi are important food resources for soil fauna. Here we ask whether the collembolan Folsomia candida shows selectivity in grazing between four saprophytic fungi (Penicillium chrysogenum, Penicillium expansum, Absidia glauca, and Cladosporium herbarum), whether grazing preference corresponds to effects on collembolan reproduction, and whether the effects of fungi on grazing and reproduction depends on the fungal substrate, which included three kinds of litter (Alnus glutinosa, Salix caprea, and Quercus robur) and one kind of agar (yeast extract). On agar, Cladosporium herbarum and Absidia glauca were the most preferred fungi and supported the highest collembolan reproduction. On fungal-colonized litter, grazing preference was more affected by litter type than by fungal species whereas collembolan reproduction was affected by both litter type and fungal species. On fungal-colonized litter, the litter type that was most preferred for grazing did not support the highest reproduction, i.e., there was an inconsistency between food preference and suitability. Alder and willow were preferred over oak for grazing, but alder supported the least reproduction.

Effects of rooting and tree growth of selected woodland species on cap integrity in a mineral capped landfill site.

PubMed

Hutchings, T R; Moffat, A J; Kemp, R A

2001-06-01

The above and below ground growth of three tree species (Alnus glutinosa, Pinus nigra var. maritima and Acer pseudoplatanus) was studied on a containment landfill site at Waterford, Hertfordshire, UK. Tree root architecture was studied using soil inspection pits excavated next to 12 trees of each species and mapped in detail. Tree height was related to soil thickness over the compacted mineral cap. No roots entered the cap where soil thickness was 1.3 m, but a few roots, especially of alder, were observed within it when the soil cover was 1.0 m or less. Micromorphological analysis of undisturbed samples of the mineral cap suggested that roots exploited weaknesses in the cap rather than actively causing penetration into it. Alder roots were more tolerant of anaerobic conditions within the cap than the other species examined. The results confirm that mineral caps should be covered by 1.5 m of soil or soil-forming material if tree establishment is intended over a restored landfill site, unless protected by other parts of a composite capping system.

Experimental woodcock management at the Moosehorn National Wildlife Refuge

USGS Publications Warehouse

Sepik, G.F.; Owen, R.B.; Coulter, M.W.; Keppie, Daniel M.; Owen, Ray B.

1977-01-01

The purpose of this study is to develop woodcock(Philohela minor) management techniques that can be easily used by the small landowner or incorporated with other land management operations such as commercial timber harvesting. The Moosehorn National Wildlife Refuge contains areas which are characteristic of the abandoned farms now being purchased for recreation or retirement as well as areas suitable for commercial forest management. Woodcock management, beginning in 1973, has centered on rejuvenation of diurnal habitat and creation of summer fields and singing grounds. Strips (10 mwide, 25 to 125 mlong and separated by 40 m) were clear~cut in two alder (Alnus sp.) stands resulting in increased diurnal use in at least one cover, increased singing male use and good alder regeneration. Small clear-cuts (30 X30 m) in a large contiguous woodland (1200 ha) with a history of few singing males resulted in an increased number of singing males despite an overall decrease in the number of singing males throughout the refuge. Management strategies and recommendations also are given.

Ecology and behaviour of the Alder Flycatcher Empidonax alnorum, Tyrannidae in winter

USGS Publications Warehouse

Foster, M.; Adams, N.J.; Slotow, R.H.

1999-01-01

The Alder Flycatcher Empidonax alnorum (Tyrannidae) winters from Colombia and Venezuela, south to northern Argentina. We studied the species in Manu National Park, Madre de Dios, Peru. In this area the species occupies riparian zones along lowland meander rivers as well as adjacent transition zone forest in the floodplain. These habitats have a number of age-related longitudinal zones (parallel to the river margin) that are short term (I-2 year) transitory stages in the succession to floodplain forest. The fast growing plant species that make up these habitats are suitable for commercial harvest for paper pulp. We examined habitat use of the species in an attempt to identify the effects of such harvest and resulting habitat loss on these birds. The Alder Flycatcher favours two longitudinal zones where it establishes territories. The territories may be long-term or transitory, and are often occupied and defended by two individuals, generally of different age. One bird tends to be more active in territory defence than the other. Defence involves patrolling, vocal duels, and chases. Birds sally for insects but also eat large quantities of fruit.

Ecology and behaviour of the Alder Flycatcher Empidonax alnorum, Tyrannidae in winter

USGS Publications Warehouse

Foster, M.; Adams, N.J.; Slotow, R.H.

1998-01-01

The Alder Flycatcher Empidonax alnorum (Tyrannidae) winters from Colombia and Venezuela, south to northern Argentina. We studied the species in Manu National Park, Madre de Dios, Peru. In this area the species occupies riparian zones along lowland meander rivers as well as adjacent transition zone forest in the floodplain. These habitats have a number of age-related longitudinal zones (parallel to the river margin) that are short term (I-2 year) transitory stages in the succession to floodplain forest. The fast growing plant species that make up these habitats are suitable for commercial harvest for paper pulp. We examined habitat use of the species in an attempt to identify the effects of such harvest and resulting habitat loss on these birds. The Alder Flycatcher favours two longitudinal zones where it establishes territories. The territories may be long-term or transitory, and are often occupied and defended by two individuals, generally of different age. One bird tends to be more active in territory defence than the other. Defence involves patrolling, vocal duels, and chases. Birds sally for insects but also eat large quantities of fruit.

The influence of reaction conditions on the Diels-Alder cycloadditions of 2-thio-3-chloroacrylamides; investigation of thermal, catalytic and microwave conditions.

PubMed

Kissane, Marie; Lynch, Denis; Chopra, Jay; Lawrence, Simon E; Maguire, Anita R

2010-12-21

The Diels-Alder cycloadditions of cyclopentadiene and 2,3-dimethyl-1,3-butadiene to a range of 2-thio-3-chloroacrylamides under thermal, catalytic and microwave conditions is described. The influence of reaction conditions on the outcome of the cycloadditions, in particular the stereoselectivity and reaction efficiency, is discussed. While the cycloadditions have been attempted at the sulfide, sulfoxide and sulfone levels of oxidation, use of the sulfoxide derivatives is clearly beneficial for stereoselective construction of Diels-Alder cycloadducts.

Synthesis of 3,4-dihydro-1,8-naphthyridin-2(1H)-ones via microwave-activated inverse electron-demand Diels–Alder reactions

PubMed Central

Fadel, Salah; Hajbi, Youssef; Khouili, Mostafa; Lazar, Said

2014-01-01

Summary Substituted 3,4-dihydro-1,8-naphthyridin-2(1H)-ones have been synthesized with the inverse electron-demand Diels–Alder reaction from 1,2,4-triazines bearing an acylamino group with a terminal alkyne side chain. Alkynes were first subjected to the Sonogashira cross-coupling reaction with aryl halides, the product of which then underwent an intramolecular inverse electron-demand Diels–Alder reaction to yield 5-aryl-3,4-dihydro-1,8-naphthyridin-2(1H)-ones by an efficient synthetic route. PMID:24605148

Dual function catalysts. Dehydrogenation and asymmetric intramolecular Diels-Alder cycloaddition of N-hydroxy formate esters and hydroxamic acids: evidence for a ruthenium-acylnitroso intermediate.

PubMed

Chow, Chun P; Shea, Kenneth J

2005-03-23

The chiral ruthenium salen complex, 13b, functions as an efficient catalyst for the sequential oxidation and asymmetric Diels-Alder cycloaddition of hydroxamic acids and N-hydroxy formate esters. This result provides evidence for the formation of a ruthenium-nitroso formate (acyl nitroso) intermediate. The Diels-Alder precursors are prepared from simple building blocks, and the cycloadducts, bridged oxazinolactams, can serve as useful intermediates in organic synthesis.

A Computational Experiment of the Endo versus Exo Preference in a Diels-Alder Reaction

ERIC Educational Resources Information Center

Rowley, Christopher N.; Woo, Tom K.

2009-01-01

We have developed and tested a computational laboratory that investigates an endo versus exo Diels-Alder cycloaddition. This laboratory employed density functional theory (DFT) calculations to study the cycloaddition of N-phenylmaleimide to furan. The endo and exo stereoisomers of the product were distinguished by building the two isomers in a…

ROLE OF RED ALDER IN NITROGEN LOSSES FROM FORESTED WATERSHEDS IN THE OREGON COAST RANGE

EPA Science Inventory

Variations in plant community composition across the landscape may have strong impacts on nutrient losses from small forested watersheds. One extreme example of this impact is the role of the nitrogen-fixing tree, red alder, in the biogeochemistry of forested watersheds in the P...

The unexpected product of Diels-Alder reaction between "indanocyclon" and maleimide

NASA Astrophysics Data System (ADS)

Dobrowolski, Michał A.; Roszkowski, Piotr; Struga, Marta; Szulczyk, Daniel

2017-02-01

A heterocyclic compound commonly known as "indanocyclon" undergoes an unexpected Diels-Alder addition with maleimide. The resulting product has been isolated and characterized in order to get an information about its structure and possible mechanism of the reaction. Extensive comparison of single crystal properties of 3-(2,8-dioxo-1,3-diphenyl-2,8-dihydrocyclopenta[a]inden-8a(1H)-yl)pyrrolidine-2,5-dione and favorable product of the reaction has been also performed.

Diels-Alder reactions of five-membered heterocycles containing one heteroatom

PubMed Central

Ding, Xiaoyuan; Nguyen, Son T.; Williams, John D.; Peet, Norton P.

2015-01-01

Diels-Alder reactions of five-membered heterocycles containing one heteroatom with an N-arylmaleimide were studied. Cycloaddition of 2,5-dimethylfuran (4) with 2-(4-methylphenyl)maleimide (3) in toluene at 60 °C gave bicyclic adduct 5. Cycloadditions of 3 with 2,5-dimethylthiophene (11) and 1,2,5-trimethylpyrrole (14) were also studied. Interestingly, the bicyclic compound 5 cleanly rearranged, with loss of water, when treated with p-toluenesulfonic acid in toluene at 80 °C to give 4,7-dimethyl-2-p-tolylisoindoline-1,3-dione (6). PMID:25838605

Effects of fertilization on growth and foliar nutrients of red alder seedlings.

Treesearch

M.A. Radwan

1987-01-01

Effects of P, K, Ca, Mg, S, Co, and Mo fertilizers on growth and foliar nutrients of red alder seedlings potted in Grove, Bunker, and Wishkah forest soils were determined. Growth in Grove soil was stimulated most by P, Ca, and P + Ca + Mg + K + S. Growth in Bunker soil was improved only by P. In Wishkah soil, best growth was obtained when P was used alone; all...

Development of annualized diameter and height growth equations for red alder: preliminary results.

Treesearch

Aaron Weiskittel; Sean M. Garber; Greg Johnson; Doug Maguire; Robert A. Monserud

2006-01-01

Most individual-tree based growth and yield models use a 5- to 10-year time step, which can make projections for a fast-growing species like red alder quite difficult. Further, it is rather cumbersome to simulate the effects of intensive silvicultural treatments such as thinning or pruning on a time step longer than one year given the highly dynamic nature of growth...

Multicatalytic asymmetric synthesis of complex tetrahydrocarbazoles via a Diels-Alder/benzoin reaction sequence.

PubMed

Liu, Yankai; Nappi, Manuel; Escudero-Adán, Eduardo C; Melchiorre, Paolo

2012-03-02

Expanding upon the recently developed aminocatalytic asymmetric indole-2,3-quinodimethane strategy, a straightforward synthesis of structurally and stereochemically complex tetrahydrocarbazoles has been devised. The chemistry's complexity-generating power was further harnessed by designing a multicatalytic, one-pot Diels-Alder/benzoin reaction sequence to stereoselectively access trans-fused tetracyclic indole-based compounds having four stereogenic centers with very high fidelity. © 2012 American Chemical Society

Enhanced cytokine synthesis of leukocytes by a beta-glucan preparation, SCG, extracted from a medicinal mushroom, Sparassis crispa.

PubMed

Nameda, Sachiko; Harada, Toshie; Miura, Noriko N; Adachi, Yoshiyuki; Yadomae, Toshiro; Nakajima, Mitsuhiro; Ohno, Naohito

2003-08-01

Sparassis crispa is edible mushroom recently cultivable in Japan. It contains significantly high content (approximately 40%) of 6-branched 1,3-beta-D-glucan showing antitumor activity in mice. We recently purified a beta-glucan preparation designated as "SCG." It was considered worth while to test SCG in vitro with whole blood collected from human volunteers. The present study is focusing on the cytokine productivity of SCG in an in vitro human system. The following results were observed: (i) SCG dose dependently enhanced IL-8 synthesis of whole blood cell culture of human peripheral blood. (ii) IL-8 synthesis was enhanced in both PBMC and PMN cultures. (iii) IL-8 synthesis was induced in the culture with autologous plasma, but significantly reduced after 56 degrees C treatment. (iv) The activity was also weak in heat inactivated fetal calf serum (FCS). (v) A complement fragment, C5a, was released by SCG dependently upon dose and kinetics. (vi) Anti-SCG natural antibody was detected in human plasma. From these facts, SCG was observed to have the capacity to activate human leukocytes and related immune system.

Abundance and Relative Distribution of Frankia Host Infection Groups Under Actinorhizal Alnus glutinosa and Non-actinorhizal Betula nigra Trees.

PubMed

Samant, Suvidha; Huo, Tian; Dawson, Jeffrey O; Hahn, Dittmar

2016-02-01

Quantitative polymerase chain reaction (qPCR) was used to assess the abundance and relative distribution of host infection groups of the root-nodule forming, nitrogen-fixing actinomycete Frankia in four soils with similar physicochemical characteristics, two of which were vegetated with a host plant, Alnus glutinosa, and two with a non-host plant, Betula nigra. Analyses of DAPI-stained cells at three locations, i.e., at a distance of less than 1 m (near stem), 2.5 m (middle crown), and 3-5 m (crown edge) from the stems of both tree species revealed no statistically significant differences in abundance. Frankiae generally accounted for 0.01 to 0.04 % of these cells, with values between 4 and 36 × 10(5) cells (g soil)(-1). In three out of four soils, abundance of frankiae was significantly higher at locations "near stem" and/or "middle crown" compared to "crown edge," while numbers at these locations were not different in the fourth soil. Frankiae of the Alnus host infection group were dominant in all samples accounting for about 75 % and more of the cells, with no obvious differences with distance to stem. In three of the soils, all of these cells were represented by strain Ag45/Mut15. In the fourth soil that was vegetated with older A. glutinosa trees, about half of these cells belonged to a different subgroup represented by strain ArI3. In all soils, the remaining cells belonged to the Elaeagnus host infection group represented by strain EAN1pec. Casuarina-infective frankiae were not found. Abundance and relative distribution of Frankia host infection groups were similar in soils under the host plant A. glutinosa and the non-host plant B. nigra. Results did thus not reveal any specific effects of plant species on soil Frankia populations.

An interpenetrating HA/G/CS biomimic hydrogel via Diels-Alder click chemistry for cartilage tissue engineering.

PubMed

Yu, Feng; Cao, Xiaodong; Zeng, Lei; Zhang, Qing; Chen, Xiaofeng

2013-08-14

In order to mimic the natural cartilage extracellular matrix, a novel biological degradable interpenetrating network hydrogel was synthesized from the gelatin (G), hyaluronic acid (HA) and chondroitin sulfate (CS) by Diels-Alder "click" chemistry. HA was modified with furylamine and G was modified with furancarboxylic acid respectively. (1)H NMR spectra and elemental analysis showed that the substitution degrees of HA-furan and G-furan were 71.5% and 44.5%. Then the hydrogels were finally synthesized by cross-linking furan-modified HA and G derivatives with dimaleimide poly(ethylene glycol) (MAL-PEG-MAL). The mechanical and degradation properties of the hydrogels could be tuned simply through varying the molar ratio between furan and maleimide. Rheological, mechanical and degradation studies demonstrated that the Diels-Alder "click" chemistry is an efficient method for preparing high performance biological interpenetrating hydrogels. This biomimic hydrogel with improved mechanical properties could have great potential applications in cartilage tissue engineering. Copyright © 2013 Elsevier Ltd. All rights reserved.

Sorocenols G and H, Anti-MRSA Oxygen Heterocyclic Diels-Alder-type Adducts from Sorocea muriculata Roots

USDA-ARS?s Scientific Manuscript database

Bioassay-guided fractionation of a root extract of Sorocea muriculata led to the isolation and identification of two new oxygen heterocyclic Diels-Alder-type adducts, sorocenols G (1) and H (2), along with lupeol-3-(3'R-hydroxytetradecanoate) and oxyresveratrol. The structures of 1 and 2 were eluci...

Enhancing Zeolite Performance by Catalyst Shaping in a Mesoscale Continuous-Flow Diels-Alder Process.

PubMed

Seghers, Sofie; Lefevere, Jasper; Mullens, Steven; De Vylder, Anton; Thybaut, Joris W; Stevens, Christian V

2018-03-26

In contrast to most lab-scale batch procedures, a continuous-flow implementation requires a thorough consideration of the solid catalyst design. In a previous study, irregular zeolite pellets were applied in a miniaturized continuous-flow reactor for the Diels-Alder reaction in the construction of norbornene scaffolds. After having faced the challenges of continuous operation, the aim of this study is to exploit catalyst structuring. To this end, microspheres with high uniformity and various sphere diameters were synthesized according to the vibrational droplet coagulation method. The influence of the use of these novel zeolite shapes in a mesoscale continuous-flow Diels-Alder process of cyclopentadiene and methyl acrylate is discussed. An impressive enhancement of catalyst lifetime is demonstrated, as even after a doubled process time of 14 h, the microspheres still exceeded the conversion after 7 h when using zeolite pellets by 30 %. A dual reason is found for this beneficial impact of catalyst shaping. The significant improvement in catalyst longevity can be attributed to the interplay of the chemical composition and the porosity structure of the microspheres. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Control of femtosecond laser driven retro-Diels-Alder-like reaction of dicyclopentadiene

PubMed Central

Das, Dipak Kumar; Goswami, Tapas; Goswami, Debabrata

2013-01-01

Using femtosecond time resolved degenerate pump-probe mass spectrometry coupled with simple linearly chirped frequency modulated pulse, we elucidate that the dynamics of retro-Diels-Alder-like reaction of diclopentadiene (DCPD) to cyclopentadiene (CPD) in supersonic molecular beam occurs in ultrafast time scale. Negatively chirped pulse enhances the ion yield of CPD, as compared to positively chirped pulse. This indicates that by changing the frequency (chirp) of the laser pulse we can control the ion yield of a chemical reaction. PMID:23814449

Biotic and abiotic variables influencing plant litter breakdown in streams: a global study.

PubMed

Boyero, Luz; Pearson, Richard G; Hui, Cang; Gessner, Mark O; Pérez, Javier; Alexandrou, Markos A; Graça, Manuel A S; Cardinale, Bradley J; Albariño, Ricardo J; Arunachalam, Muthukumarasamy; Barmuta, Leon A; Boulton, Andrew J; Bruder, Andreas; Callisto, Marcos; Chauvet, Eric; Death, Russell G; Dudgeon, David; Encalada, Andrea C; Ferreira, Verónica; Figueroa, Ricardo; Flecker, Alexander S; Gonçalves, José F; Helson, Julie; Iwata, Tomoya; Jinggut, Tajang; Mathooko, Jude; Mathuriau, Catherine; M'Erimba, Charles; Moretti, Marcelo S; Pringle, Catherine M; Ramírez, Alonso; Ratnarajah, Lavenia; Rincon, José; Yule, Catherine M

2016-04-27

Plant litter breakdown is a key ecological process in terrestrial and freshwater ecosystems. Streams and rivers, in particular, contribute substantially to global carbon fluxes. However, there is little information available on the relative roles of different drivers of plant litter breakdown in fresh waters, particularly at large scales. We present a global-scale study of litter breakdown in streams to compare the roles of biotic, climatic and other environmental factors on breakdown rates. We conducted an experiment in 24 streams encompassing latitudes from 47.8° N to 42.8° S, using litter mixtures of local species differing in quality and phylogenetic diversity (PD), and alder (Alnus glutinosa) to control for variation in litter traits. Our models revealed that breakdown of alder was driven by climate, with some influence of pH, whereas variation in breakdown of litter mixtures was explained mainly by litter quality and PD. Effects of litter quality and PD and stream pH were more positive at higher temperatures, indicating that different mechanisms may operate at different latitudes. These results reflect global variability caused by multiple factors, but unexplained variance points to the need for expanded global-scale comparisons. © 2016 The Author(s).

Biotic and abiotic variables influencing plant litter breakdown in streams: a global study

PubMed Central

Pearson, Richard G.; Hui, Cang; Gessner, Mark O.; Pérez, Javier; Alexandrou, Markos A.; Graça, Manuel A. S.; Cardinale, Bradley J.; Albariño, Ricardo J.; Arunachalam, Muthukumarasamy; Barmuta, Leon A.; Boulton, Andrew J.; Bruder, Andreas; Callisto, Marcos; Chauvet, Eric; Death, Russell G.; Dudgeon, David; Encalada, Andrea C.; Ferreira, Verónica; Figueroa, Ricardo; Flecker, Alexander S.; Gonçalves, José F.; Helson, Julie; Iwata, Tomoya; Jinggut, Tajang; Mathooko, Jude; Mathuriau, Catherine; M'Erimba, Charles; Moretti, Marcelo S.; Pringle, Catherine M.; Ramírez, Alonso; Ratnarajah, Lavenia; Rincon, José; Yule, Catherine M.

2016-01-01

Plant litter breakdown is a key ecological process in terrestrial and freshwater ecosystems. Streams and rivers, in particular, contribute substantially to global carbon fluxes. However, there is little information available on the relative roles of different drivers of plant litter breakdown in fresh waters, particularly at large scales. We present a global-scale study of litter breakdown in streams to compare the roles of biotic, climatic and other environmental factors on breakdown rates. We conducted an experiment in 24 streams encompassing latitudes from 47.8° N to 42.8° S, using litter mixtures of local species differing in quality and phylogenetic diversity (PD), and alder (Alnus glutinosa) to control for variation in litter traits. Our models revealed that breakdown of alder was driven by climate, with some influence of pH, whereas variation in breakdown of litter mixtures was explained mainly by litter quality and PD. Effects of litter quality and PD and stream pH were more positive at higher temperatures, indicating that different mechanisms may operate at different latitudes. These results reflect global variability caused by multiple factors, but unexplained variance points to the need for expanded global-scale comparisons. PMID:27122551

Distinct temperature sensitivity among taiga and tundra shrubs in Alaska

NASA Astrophysics Data System (ADS)

Andreu-Hayles, L.; Anchukaitis, K. J.; D'Arrigo, R.

2014-12-01

Shrub expansion into Arctic and alpine tundra ecosystems is well documented, mostly over the last 50 years, based on remote sensing data, aerial photography, and in-situ observations. Warming temperatures are considered the main driver of the observed change in shrub vegetation patterns. Here, we assess the relationship between temperatures and shrub growth from five populations of Salix spp. (willow) and Alnus spp. (alder) in Alaska growing within the tundra and the boreal forest (~taiga) using dendrochronological techniques. The three tundra shrub sites are located on the Dalton Highway north from Toolik Lake (~69ºN 148ºW), whereas the two taiga shrub sites are located closer to Fairbanks at the Twelve Mile Summit site (~65ºN 146ºW). Because shrub ages vary among the studied populations lead to different time spans for the ring-width chronologies generated, a common period with available satellite data spanning from 1982 to 2010 was selected for this study. All tundra shrub chronologies shared a strong positive response to summer temperatures despite growing in heterogeneous site conditions and belonging to different species. In contrast, in the taiga, summer temperatures enhance willow growth, whereas alder growth appears almost insensitive to temperature over the interval studied. Extending the analyses back in time, a very strong positive relationship was found between alder ring-width and June temperatures prior to 1970. This phenomenon, a weakening of the previously existing relationship between growth and temperatures, was also detected in white spruce (Picea glauca) growing at the same site, and it is known in the literature as the 'divergence problem'. Thus, at this taiga location, alder shrubs and trees seem to have similar growth patterns. Summer temperatures no longer seem to enhance taiga alder growth. Shrubs of different species exposed to the same climatic conditions can exhibit varied growth responses. The distinct temperature sensitivities

Microwave-Enhanced Organic Syntheses for the Undergraduate Laboratory: Diels-Alder Cycloaddition, Wittig Reaction, and Williamson Ether Synthesis

ERIC Educational Resources Information Center

Baar, Marsha R.; Falcone, Danielle; Gordon, Christopher

2010-01-01

Microwave heating enhanced the rate of three reactions typically performed in our undergraduate organic chemistry laboratory: a Diels-Alder cycloaddition, a Wittig salt formation, and a Williamson ether synthesis. Ninety-minute refluxes were shortened to 10 min using a laboratory-grade microwave oven. In addition, yields improved for the Wittig…

Thiourea-catalyzed Diels–Alder reaction of a naphthoquinone monoketal dienophile

PubMed Central

Kramer, Carsten S

2013-01-01

Summary A variety of organocatalysts were screened for the catalysis of the naphthoquinone monoketal Diels–Alder reaction. In this study we found that Schreiner's thiourea catalyst 10 and Jacobson's thiourea catalyst 12 facilitate the cycloaddition of the sterically hindered naphthoquinone monoketal dienophile 3 with diene 4. The use of thiourea catalysis allowed for the first time the highly selective synthesis of the exo-product 2a in up to 63% yield. In this reaction a new quaternary center was built. The so formed cycloaddition product 2a represents the ABC tricycle of beticolin 0 (1) and is also a valuable model substrate for the total synthesis of related natural products. PMID:23946836

A Thermal Dehydrogenative Diels–Alder Reaction of Styrenes for the Concise Synthesis of Functionalized Naphthalenes

PubMed Central

Kocsis, Laura S.; Benedetti, Erica

2012-01-01

Functionalized naphthalenes are valuable building blocks in many important areas. A microwave-assisted, intramolecular dehydrogenative Diels-Alder reaction of styrenyl derivatives to provide cyclopenta[b]naphthalene substructures not previously accessible using existing synthetic methods is described. The synthetic utility of these uniquely functionalized naphthalenes was demonstrated by a single-step conversion of one of these cycloadducts to a fluorophore bearing a structural resemblance to Prodan. PMID:22913473

A thermal dehydrogenative Diels-Alder reaction of styrenes for the concise synthesis of functionalized naphthalenes.

PubMed

Kocsis, Laura S; Benedetti, Erica; Brummond, Kay M

2012-09-07

Functionalized naphthalenes are valuable building blocks in many important areas. A microwave-assisted, intramolecular dehydrogenative Diels-Alder reaction of styrenyl derivatives to provide cyclopenta[b]naphthalene substructures not previously accessible using existing synthetic methods is described. The synthetic utility of these uniquely functionalized naphthalenes was demonstrated by a single-step conversion of one of these cycloadducts to a fluorophore bearing a structural resemblance to Prodan.

On the theory of Brownian motion with the Alder-Wainwright effect

NASA Astrophysics Data System (ADS)

Okabe, Yasunori

1986-12-01

The Stokes-Boussinesq-Langevin equation, which describes the time evolution of Brownian motion with the Alder-Wainwright effect, can be treated in the framework of the theory of KMO-Langevin equations which describe the time evolution of a real, stationary Gaussian process with T-positivity (reflection positivity) originating in axiomatic quantum field theory. After proving the fluctuation-dissipation theorems for KMO-Langevin equations, we obtain an explicit formula for the deviation from the classical Einstein relation that occurs in the Stokes-Boussinesq-Langevin equation with a white noise as its random force. We are interested in whether or not it can be measured experimentally.

Diels-Alder Synthesis of endo-cis-N-phenylbicyclo[2.2.2]oct-5-en-2,3-dicarboximide

ERIC Educational Resources Information Center

Baar, Marsha R.; Wustholz, Kristin

2005-01-01

A study investigated the Diels-Alder synthesis of endo-cis-N-phenylbicyclo [2.2.2]oct-5-en-2,3-dicarboximide. The amount of time taken by a reaction between the 1,3-cyclohexadiene and N-phenylmaleimide at room temperature and also whether the desired cycloadduct would precipitate directly from the reaction mixture was examined.

Detection of transient radical cations in electron transfer-initiated Diels-Alder reactions by electrospray ionization mass spectrometry.

PubMed

Fürmeier, Sven; Metzger, Jürgen O

2004-11-10

The coupling of a simple microreactor to an atmospheric pressure ion source, such as electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI), allows the investigation of reactions in solution by mass spectrometry. The tris(p-bromophenyl)aminium hexachloroantimonate (1(*)(+)SbCl(6)(-))-initiated reactions of phenylvinylsulfide (2) and cyclopentadiene (3) and of trans-anethole (5) and isoprene (6) and the dimerization of 1,3-cyclohexadiene (8) to give the respective Diels-Alder products were studied. These preparatively interesting reactions proceed as radical cation chain reactions via the transient radical cations of the respective dienophiles and of the respective Diels-Alder addition products. These radical cations could be detected directly and characterized unambiguously in the reacting solution by ESI-MS-MS. The identity was confirmed by comparison with MS-MS spectra of the authentic radical cations obtained by APCI-MS and by CID experiments of the corresponding molecular ions generated by EI-MS. In addition, substrates and products could be monitored easily in the reacting solution by APCI-MS.

Continuous-flow retro-Diels-Alder reaction: an efficient method for the preparation of pyrimidinone derivatives.

PubMed

Nekkaa, Imane; Palkó, Márta; Mándity, István M; Fülöp, Ferenc

2018-01-01

The syntheses of various pyrimidinones as potentially bioactive products by means of the highly controlled continuous-flow retro-Diels-Alder reaction of condensed pyrimidinone derivatives are presented. Noteworthy, the use of this approach allowed us to rapidly screen a selection of conditions and quickly confirm the viability of preparing the desired pyrimidinones in short reaction times. Yields typically higher than those published earlier using conventional batch or microwave processes were achieved.

Magnetic hyaluronic acid nanospheres via aqueous Diels-Alder chemistry to deliver dexamethasone for adipose tissue engineering.

PubMed

Jia, Yang; Fan, Ming; Chen, Huinan; Miao, Yuting; Xing, Lian; Jiang, Bohong; Cheng, Qifan; Liu, Dongwei; Bao, Weikang; Qian, Bin; Wang, Jionglu; Xing, Xiaodong; Tan, Huaping; Ling, Zhonghua; Chen, Yong

2015-11-15

Biopolymer-based nanospheres have great potential in the field of drug delivery and tissue regenerative medicine. In this work, we present a flexible way to conjugate a magnetic hyaluronic acid (HA) nanosphere system that are capable of vectoring delivery of adipogenic factor, e.g. dexamethasone, for adipose tissue engineering. Conjugation of nanospheres was established by aqueous Diels-Alder chemistry between furan and maleimide of HA derivatives. Simultaneously, a furan functionalized dexamethasone peptide, GQPGK, was synthesized and covalently immobilized into the nanospheres. The magnetic HA nanospheres were fabricated by encapsulating super-paramagnetic iron oxide nanoparticles, which exhibited quick magnetic sensitivity. The aqueous Diels-Alder chemistry made nanospheres high binding efficiency of dexamethasone, and the vectoring delivery of dexamethasone could be easily controlled by a external magnetic field. The potential application of the magnetic HA nanospheres on vectoring delivery of adipogenic factor was confirmed by co-culture of human adipose-derived stem cells (ASCs). In vitro cytotoxicity tests demonstrated that incorporation of dexamethasone into magnetic HA nanospheres showed high efficiency to promote ASCs viabilities, in particular under a magnetic field, which suggested a promising future for adipose regeneration applications. Copyright © 2015 Elsevier Inc. All rights reserved.

The Nitrosocarbonyl Hetero-Diels–Alder Reaction as a Useful Tool for Organic Syntheses

PubMed Central

Bodnar, Brian S.

2014-01-01

Organic transformations that result in the formation of multiple covalent bonds within the same reaction are some of the most powerful tools in synthetic organic chemistry. Nitrosocarbonyl hetero-Diels–Alder (HDA) reactions allow for the simultaneous stereospecific introduction of carbon–nitrogen and carbon–oxygen bonds in one synthetic step, and provide direct access to 3,6-dihydro-1,2-oxazines. This Review describes the development of the nitrosocarbonyl HDA reaction and the utility of the resulting oxazine ring in the synthesis of a variety of important, biologically active molecules. PMID:21520360

Continuous-flow retro-Diels–Alder reaction: an efficient method for the preparation of pyrimidinone derivatives

PubMed Central

Nekkaa, Imane; Palkó, Márta; Mándity, István M

2018-01-01

The syntheses of various pyrimidinones as potentially bioactive products by means of the highly controlled continuous-flow retro-Diels–Alder reaction of condensed pyrimidinone derivatives are presented. Noteworthy, the use of this approach allowed us to rapidly screen a selection of conditions and quickly confirm the viability of preparing the desired pyrimidinones in short reaction times. Yields typically higher than those published earlier using conventional batch or microwave processes were achieved. PMID:29507637

Simultaneous analysis of 70 pesticides using HPlc/MS/MS: a comparison of the multiresidue method of Klein and Alder and the QuEChERS method.

PubMed

Riedel, Melanie; Speer, Karl; Stuke, Sven; Schmeer, Karl

2010-01-01

Since 2003, two new multipesticide residue methods for screening crops for a large number of pesticides, developed by Klein and Alder and Anastassiades et al. (Quick, Easy, Cheap, Effective, Rugged, and Safe; QuEChERS), have been published. Our intention was to compare these two important methods on the basis of their extraction efficiency, reproducibility, ruggedness, ease of use, and speed. In total, 70 pesticides belonging to numerous different substance classes were analyzed at two concentration levels by applying both methods, using five different representative matrixes. In the case of the QuEChERS method, the results of the three sample preparation steps (crude extract, extract after SPE, and extract after SPE and acidification) were compared with each other and with the results obtained with the Klein and Alder method. The extraction efficiencies of the QuEChERS method were far higher, and the sample preparation was much quicker when the last two steps were omitted. In most cases, the extraction efficiencies after the first step were approximately 100%. With extraction efficiencies of mostly less than 70%, the Klein and Alder method did not compare favorably. Some analytes caused problems during evaluation, mostly due to matrix influences.

Diels-Alder functionalized carbon nanotubes for bone tissue engineering: in vitro/in vivo biocompatibility and biodegradability

NASA Astrophysics Data System (ADS)

Mata, D.; Amaral, M.; Fernandes, A. J. S.; Colaço, B.; Gama, A.; Paiva, M. C.; Gomes, P. S.; Silva, R. F.; Fernandes, M. H.

2015-05-01

The risk-benefit balance for carbon nanotubes (CNTs) dictates their clinical fate. To take a step forward at this crossroad it is compulsory to modulate the CNT in vivo biocompatibility and biodegradability via e.g. chemical functionalization. CNT membranes were functionalised combining a Diels-Alder cycloaddition reaction to generate cyclohexene (-C6H10) followed by a mild oxidisation to yield carboxylic acid groups (-COOH). In vitro proliferation and osteogenic differentiation of human osteoblastic cells were maximized on functionalized CNT membranes (p,f-CNTs). The in vivo subcutaneously implanted materials showed a higher biological reactivity, thus inducing a slighter intense inflammatory response compared to non-functionalized CNT membranes (p-CNTs), but still showing a reduced cytotoxicity profile. Moreover, the in vivo biodegradation of CNTs was superior for p,f-CNT membranes, likely mediated by the oxidation-induced myeloperoxidase (MPO) in neutrophil and macrophage inflammatory milieus. This proves the biodegradability faculty of functionalized CNTs, which potentially avoids long-term tissue accumulation and triggering of acute toxicity. On the whole, the proposed Diels-Alder functionalization accounts for the improved CNT biological response in terms of the biocompatibility and biodegradability profiles. Therefore, CNTs can be considered for use in bone tissue engineering without notable toxicological threats.The risk-benefit balance for carbon nanotubes (CNTs) dictates their clinical fate. To take a step forward at this crossroad it is compulsory to modulate the CNT in vivo biocompatibility and biodegradability via e.g. chemical functionalization. CNT membranes were functionalised combining a Diels-Alder cycloaddition reaction to generate cyclohexene (-C6H10) followed by a mild oxidisation to yield carboxylic acid groups (-COOH). In vitro proliferation and osteogenic differentiation of human osteoblastic cells were maximized on functionalized CNT

Illustrating the Utility of X-Ray Crystallography for Structure Elucidation through a Tandem Aldol Condensation/Diels-Alder Reaction Sequence

ERIC Educational Resources Information Center

Hoang, Giang T.; Kubo, Tomohiro; Young, Victor G., Jr.; Kautzky, Jacob A.; Wissinger, Jane E.

2015-01-01

Two introductory organic chemistry laboratory experiments are described based on the Diels-Alder reaction of 2,3,4,5-tetraphenylcyclopentadienone, which is synthesized prior to or in a one-pot reaction, with styrene. Students are presented with three possible products, the "endo" and "exo" diastereomers and the decarbonylated…

Ammonium nitrate, urea, and biuret fertilizers increase volume growth of 57-year-old douglas-fir trees within a gradient of nitrogen deficiency. Forest Service research paper

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, R.E.; Reukema, D.L.; Hazard, J.W.

1996-03-01

In a nitrogen-deficient plantation in southwest Washington, the authors (1) compared effects of 224 kg N/ha as ammonium nitrate, urea, and biuret on volume growth of dominant and codominant Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco); (2) determined how 8-year response of these trees to fertilization was related to their distance from a strip of the plantation interplanted with nitrogen-fixing red alder (alnus rubra Bong.); and (3) observed effects of biuret on understory vegetation. On both sides of the strip centerline, the authors grouped subject trees into 30 plots of 4 trees each, based on slope position and distance frommore » alder. The authors randomly assigned three fertilizers and a control within each plot. They analyzed separately data from east and west of the mixed stand certerline. Initial volume differed greatly among the 120 trees on each side, so they used covariance analysis to adjust observed treatment means. Adjusted mean volume growth was increased (p equal to or less than 0.10) by 22 to 28 percent on the east side and by 11 to 14 percent on the west side, with no significant difference in response to the three fertilizers.« less

Biodegradable hyaluronic acid hydrogels to control release of dexamethasone through aqueous Diels-Alder chemistry for adipose tissue engineering.

PubMed

Fan, Ming; Ma, Ye; Zhang, Ziwei; Mao, Jiahui; Tan, Huaping; Hu, Xiaohong

2015-11-01

A robust synthetic strategy of biopolymer-based hydrogels has been developed where hyaluronic acid derivatives reacted through aqueous Diels-Alder chemistry without the involvement of chemical catalysts, allowing for control and sustain release of dexamethasone. To conjugate the hydrogel, furan and maleimide functionalized hyaluronic acid were synthesized, respectively, as well as furan functionalized dexamethasone, for the covalent immobilization. Chemical structure, gelation time, morphologies, swelling kinetics, weight loss, compressive modulus and dexamethasone release of the hydrogel system in PBS at 37°C were studied. The results demonstrated that the aqueous Diels-Alder chemistry provides an extremely selective reaction and proceeds with high efficiency for hydrogel conjugation and covalent immobilization of dexamethasone. Cell culture results showed that the dexamethasone immobilized hydrogel was noncytotoxic and preserved proliferation of entrapped human adipose-derived stem cells. This synthetic approach uniquely allows for the direct fabrication of biologically functionalized gel scaffolds with ideal structures for adipose tissue engineering, which provides a competitive alternative to conventional conjugation techniques such as copper mediated click chemistry. Copyright © 2015. Published by Elsevier B.V.

L-Pyroglutamic Sulphonamide as Hydrogen-Bonding Organocatalyst: Enantioselective Diels-Alder Cyclization to Construct Carbazolespirooxindoles.

PubMed

Ren, Ji-Wei; Wang, Jing; Xiao, Jun-An; Li, Jun; Xiang, Hao-Yue; Chen, Xiao-Qing; Yang, Hua

2017-06-16

Hydrogen-bonding organocatalysts L-pyroglutamic sulphonamides were readily synthesized for the first time by fully exploiting the potentials of L-pyroglutamic acid. The newly designed catalyst was successfully applied in catalyzing asymmetric Diels-Alder cyclization of methyleneindolinones with 2-vinyl-1H-indoles to efficiently assemble carbazolespirooxindoles in excellent stereoselectivity (up to 99% ee, >20:1 dr) and yields (up to 99%). Mechanistic studies disclosed that the well-designed hydrogen-bonding modes between L-pyroglutamic sulphonamide and substrates were crucial for stereocontrol in the cyclization.

Rate variations of a hetero-Diels--Alder reaction in supercritical fluid CO{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thompson, R.L.; Glaeser, R.; Bush, D.

1999-11-01

The hetero-Diels-Alder reaction between anthracene and excess 4-phenyl-1,2,4-triazoline-3,5-dione has been investigated in supercritical CO{sub 2} at 40 C and pressures between 75 and 216 bar. Biomolecular reaction rate constants have been measured via fluorescence spectroscopy by following the decrease in anthracene concentration with reaction time. The reaction rate is elevated in the vicinity of the critical pressure. This difference is consistent with local composition enhancement and can be modeled with the Peng-Robinson equation of state.

Tree-mediated methane emissions from tropical and temperate peatlands.

NASA Astrophysics Data System (ADS)

Pangala, S. R.; Gauci, V.; Hornibrook, E. R. C.; Gowing, D. J.

2012-04-01

Methane production and transport processes in peatlands are fairly well understood, but growing evidence for emission of methane through trees has highlighted the need to revisit methane transport processes. In wetland trees, morphological adaptations such as development of hypertrophied lenticels, aerenchyma and adventitious roots in response to soil anoxia mediates gas transport, transporting both oxygen from the atmosphere to oxygen-deprived roots and soil-produced methane from the root-zone to the atmosphere. Although, tree-mediated methane emissions from temperate tree species have been confirmed, methane emissions from tropical tree species and processes that control tree-mediated methane emissions remain unclear. This study explains the role of trees in transporting soil-produced methane to the atmosphere and uncovers the principal mechanisms of tree-mediated methane emissions. Methane emissions from eight tropical tree species and two temperate tree species were studied in situ. The mechanisms and controls on tree-mediated methane emissions were investigated using three year old common alder (Alnus glutinosa; 50 trees) grown under two artificially controlled water-table positions. Methane fluxes from whole mesocosms, the soil surface and tree stems were measured using static closed chambers. Both temperate and tropical tree species released significant quantities of methane, with tropical trees dominating ecosystem level methane fluxes. In temperate peatlands, both the methane gas transport mechanism and quantity of methane emitted from stems is tree-species dependent. In Alnus glutinosa, no correlations were observed between stomatal behaviour and tree-mediated methane emissions, however, stem methane emissions were positively correlated with both stem lenticel density and dissolved soil methane concentration. In Alnus glutinosa, no emissions were observed from leaf surfaces. The results demonstrate that exclusion of tree-mediated methane emissions from

Diels-Alder functionalized carbon nanotubes for bone tissue engineering: in vitro/in vivo biocompatibility and biodegradability.

PubMed

Mata, D; Amaral, M; Fernandes, A J S; Colaço, B; Gama, A; Paiva, M C; Gomes, P S; Silva, R F; Fernandes, M H

2015-01-01

The risk-benefit balance for carbon nanotubes (CNTs) dictates their clinical fate. To take a step forward at this crossroad it is compulsory to modulate the CNT in vivo biocompatibility and biodegradability via e.g. chemical functionalization. CNT membranes were functionalised combining a Diels-Alder cycloaddition reaction to generate cyclohexene (-C6H10) followed by a mild oxidisation to yield carboxylic acid groups (-COOH). In vitro proliferation and osteogenic differentiation of human osteoblastic cells were maximized on functionalized CNT membranes (p,f-CNTs). The in vivo subcutaneously implanted materials showed a higher biological reactivity, thus inducing a slighter intense inflammatory response compared to non-functionalized CNT membranes (p-CNTs), but still showing a reduced cytotoxicity profile. Moreover, the in vivo biodegradation of CNTs was superior for p,f-CNT membranes, likely mediated by the oxidation-induced myeloperoxidase (MPO) in neutrophil and macrophage inflammatory milieus. This proves the biodegradability faculty of functionalized CNTs, which potentially avoids long-term tissue accumulation and triggering of acute toxicity. On the whole, the proposed Diels-Alder functionalization accounts for the improved CNT biological response in terms of the biocompatibility and biodegradability profiles. Therefore, CNTs can be considered for use in bone tissue engineering without notable toxicological threats.

The nitrosocarbonyl hetero-Diels-Alder reaction as a useful tool for organic syntheses.

PubMed

Bodnar, Brian S; Miller, Marvin J

2011-06-14

Organic transformations that result in the formation of multiple covalent bonds within the same reaction are some of the most powerful tools in synthetic organic chemistry. Nitrosocarbonyl hetero-Diels-Alder (HDA) reactions allow for the simultaneous stereospecific introduction of carbon-nitrogen and carbon-oxygen bonds in one synthetic step, and provide direct access to 3,6-dihydro-1,2-oxazines. This Review describes the development of the nitrosocarbonyl HDA reaction and the utility of the resulting oxazine ring in the synthesis of a variety of important, biologically active molecules. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Alnus peptides modify membrane porosity and induce the release of nitrogen-rich metabolites from nitrogen-fixing Frankia.

PubMed

Carro, Lorena; Pujic, Petar; Alloisio, Nicole; Fournier, Pascale; Boubakri, Hasna; Hay, Anne E; Poly, Franck; François, Philippe; Hocher, Valerie; Mergaert, Peter; Balmand, Severine; Rey, Marjolaine; Heddi, Abdelaziz; Normand, Philippe

2015-08-01

Actinorhizal plant growth in pioneer ecosystems depends on the symbiosis with the nitrogen-fixing actinobacterium Frankia cells that are housed in special root organs called nodules. Nitrogen fixation occurs in differentiated Frankia cells known as vesicles. Vesicles lack a pathway for assimilating ammonia beyond the glutamine stage and are supposed to transfer reduced nitrogen to the plant host cells. However, a mechanism for the transfer of nitrogen-fixation products to the plant cells remains elusive. Here, new elements for this metabolic exchange are described. We show that Alnus glutinosa nodules express defensin-like peptides, and one of these, Ag5, was found to target Frankia vesicles. In vitro and in vivo analyses showed that Ag5 induces drastic physiological changes in Frankia, including an increased permeability of vesicle membranes. A significant release of nitrogen-containing metabolites, mainly glutamine and glutamate, was found in N2-fixing cultures treated with Ag5. This work demonstrates that the Ag5 peptide is central for Frankia physiology in nodules and uncovers a novel cellular function for this large and widespread defensin peptide family.

Exploring the influence of Diels-Alder linker length on photothermal molecule release from gold nanorods.

PubMed

Vetterlein, Claudia; Vásquez, Rodrigo; Bolaños, Karen; Acosta, Gerardo A; Guzman, Fanny; Albericio, Fernando; Celis, Freddy; Campos, Marcelo; Kogan, Marcelo J; Araya, Eyleen

2018-06-01

We studied the photothermal release of carboxyfluorescein (CF) linked to the gold surface of gold nanorods (GNRs) by two Diels-Alder adducts of different lengths (n = 4 and n = 9). The functionalized GNRs were irradiated with infrared light to produce photothermal release of CF by a retro-Diels-Alder reaction. The adducts were chemisorbed on the GNRs and the functionalized nanoparticles were characterized by UV-vis, DLS, zeta potential and Raman and surface-enhanced Raman spectroscopy (SERS). On the basis of the degree of nanoparticle functionalization and the SERS results, we inferred the orientation of CF on the surface of the gold nanoparticle. Moreover, we determined the photothermal release profiles of CF from the gold surface by laser irradiation. The release was faster for the longer linker (n = 9). SERS revealed that, for the shorter linker (n = 4), molecules are oriented perpendicularly with respect to the gold surface, thereby maintaining the CF far from the surface. In contrast, the longer linker was observed to be tilted, thus maintaining CF close to the gold surface and therefore potentially favoring the photothermal transfer of energy. These results are relevant for the future development of the spatial and temporal controlled release of drugs by means of gold nanoparticles. Copyright © 2018 Elsevier B.V. All rights reserved.

A Tunable and Enantioselective Hetero-Diels-Alder Reaction Provides Access to Distinct Piperidinoyl Spirooxindoles.

PubMed

Jayakumar, Samydurai; Louven, Kathrin; Strohmann, Carsten; Kumar, Kamal

2017-12-11

The active complexes of chiral N,N'-dioxide ligands with dysprosium and magnesium salts catalyze the hetero-Diels-Alder reaction between 2-aza-3-silyloxy-butadienes and alkylidene oxindoles to selectively form 3,3'- and 3,4'-piperidinoyl spirooxindoles, respectively, in very high yields and with excellent enantioselectivities. The exo-selective asymmetric cycloaddition successfully regaled the construction of sp 3 -rich and highly substituted natural-product-based spirooxindoles supporting many chiral centers, including contiguous all-carbon quaternary centers. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Studies toward the synthesis of palhinine lycopodium alkaloids: a Morita-Baylis-Hillman/intramolecular Diels-Alder approach.

PubMed

Sizemore, Nicholas; Rychnovsky, Scott D

2014-02-07

A synthetic route to the isotwistane core of palhinine lycopodium alkaloids is described. A Morita-Baylis-Hillman/intramolecular Diels-Alder (IMDA) strategy sets the vicinal all-carbon quaternary centers present in this family of natural products. The regioselectivity of the IMDA reaction is dictated by the conditions employed for silyl enol ether formation, with one set of conditions providing the core of cardionine and alternate conditions generating the desired isotwistane core of isopalhinine.

[Biomass distribution patterns of Alnus hirsuta and Betula platyphylla-swamp ecotone communities in Changbai Mountains].

PubMed

Mu, Changcheng; Wan, Shucheng; Su, Ping; Song, Hongwen; Sun, Zhihu

2004-12-01

In order to reveal the growth patterns of dominant tree species and the distribution patterns of community biomass along the horizontal environmental gradients or among the vertical layers of communities in Changbai Mountains, this paper studied the biomass distribution patterns of Alnus hirsuta-swamp and Betula platyphylla-swamp ecotone communities. The results showed that there were some differences in growth rate and in adaptability to habitats between A. hirsuta and B. platyphylla. In the wetland habitats of the ecotone, A. hirsuta grew 1-2 times faster than B. platyphylla, but along the gradient from swamp to forest, it grew slowly, while B. platyphylla grew fast. Therefore, A. hirsuta was a favorite tree species in wetland habitats. The distribution pattern of organ biomass was similar between A. hirsute and B. platyphylla, the trunk being 1/2, tree root 1/4, branch 1/10, bark 1.5/20, and leaf 1/20. The vertical distribution pattern of biomass was also similar between A. hirsute-swamp and B. platyphylla-swamp ecotone communities, the tree, shrub, and herbage layer accounted for 87%-90%, 7%-9%, and 2%-3%, respectively in the whole ecotone communities. The community biomass increased linearly from swamp to forest with the change of environment factors.

Phosphorous fertilization alleviates drought effects on Alnus cremastogyne by regulating its antioxidant and osmotic potential.

PubMed

Tariq, Akash; Pan, Kaiwen; Olatunji, Olusanya Abiodun; Graciano, Corina; Li, Zilong; Sun, Feng; Zhang, Lin; Wu, Xiaogang; Chen, Wenkai; Song, Dagang; Huang, Dan; Xue, Tan; Zhang, Aiping

2018-04-04

Alnus cremastogyne, a broad-leaved tree endemic to south-western China, has both commercial and restoration importance. However, little is known of its morphological, physiological and biochemical responses to drought and phosphorous (P) application. A randomized experimental design was used to investigate how drought affected A. cremastogyne seedlings, and the role that P applications play in these responses. Drought had significant negative effects on A. cremastogyne growth and metabolism, as revealed by reduced biomass (leaf, shoot and root), leaf area, stem diameter, plant height, photosynthetic rate, leaf relative water content, and photosynthetic pigments, and a weakened antioxidative defence mechanism and high lipid peroxidation level. However, the reduced leaf area and enhanced osmolyte (proline and soluble sugars) accumulation suggests drought avoidance and tolerance strategies in this tree. Applying P significantly improved the leaf relative water content and photosynthetic rate of drought-stressed seedlings, which may reflect increased anti-oxidative enzyme (superoxide dismutase, catalase and peroxidase) activities, osmolyte accumulation, soluble proteins, and decreased lipid peroxidation levels. However, P had only a slight or negligible effect on the well-watered plants. A. cremastogyne is sensitive to drought stress, but P facilitates and improves its metabolism primarily via biochemical and physiological rather than morphological adjustments, regardless of water availability.

Characterization of vanadium ion uptake in sulfonated diels alder poly(phenylene) membranes

DOE PAGES

Lawton, Jamie; Jones, Amanda; Tang, Zhijiang; ...

2015-11-28

Sulfonated diels alder poly(phenylene) (SDAPP), alternative aromatic hydrocarbon membranes for vanadium redox flow batteries (VRFBs) are characterized using electron paramagnetic resonance (EPR). Membranes soaked in sulfuric acid and vanadyl sulfate are analyzed to determine the membrane environment in which the vanadyl ion (VO 2+) diffuses in the membranes. These results are compared to Nafion 117 membranes. In contrast to Nafion, the VO 2+ in SDAPP membranes exists in two different environments. The results of analysis of rotational diffusion determined from fits the EPR spectral lineshapes in comparison with previously reported permeation studies and measurements of partitioning functions reported here suggestmore » that the diffusion pathways in SDAPP are very different than in Nafion.« less

Fast Hetero-Diels-Alder Reactions Using 4-Phenyl-1,2,4-Triazoline-3,5-Dione (PTAD) as the Dienophile

ERIC Educational Resources Information Center

Celius, Tevye C.

2010-01-01

A hetero-Diels-Alder reaction that proceeds rapidly and only requires a simple filtration to purify the product is presented. The dienophile, 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD), is prepared by the heterogeneous oxidation of 4-phenylurazole by the bromenium ion, Br[superscript +], generated in situ by the oxidation of potassium bromide by…

Spectacular Rate Enhancement of the Diels-Alder Reaction at the Ionic Liquid/n-Hexane Interface.

PubMed

Beniwal, Vijay; Manna, Arpan; Kumar, Anil

2016-07-04

The use of the ionic liquid/n-hexane interface as a new class of reaction medium for the Diels-Alder reaction gives large rate enhancements of the order of 10(6) to 10(8) times and high stereoselectivity, as compared to homogeneous media. The rate enhancement is attributed to the H-bonding abilities and polarities of the ionic liquids, whereas the hydrophobicity of ionic liquids was considered to be the factor in controlling stereoselectivity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Diels-Alder cycloadditions by microwave-assisted, continuous flow organic synthesis (MACOS): the role of metal films in the flow tube.

PubMed

Shore, Gjergji; Organ, Michael G

2008-02-21

Thin Pd films have been deposited on the inside of capillary-sized tubes through which compounds undergoing Diels-Alder reactions have been flowed while being heated with microwave irradiation; dramatic rate accelerations are observed in the presence of the film, which has been shown to play both a heating and catalytic role.

Effect of SCG, 1,3-beta-D-glucan from Sparassis crispa on the hematopoietic response in cyclophosphamide induced leukopenic mice.

PubMed

Harada, Toshie; Miura, Noriko; Adachi, Yoshiyuki; Nakajima, Mitsuhiro; Yadomae, Toshiro; Ohn, Naohito

2002-07-01

Sparassis crispa Fr. is an edible mushroom recently cultivable in Japan. It contains a remarkably high content of 6-branched 1,3-beta-D-glucan showing antitumor activity. Using ion-exchange chromatography, a purified beta-glucan preparation, SCG, was prepared. In this study, we examined the hematopoietic response by SCG in cyclophosphamide (CY)-induced leukopenic mice. SCG enhanced the hematopoietic response in CY induced leukopenic mice by intraperitoneal routes over a wide range of concentrations. SCG enhanced the hematopoietic response in CY-treated mice by prior or post administration. Analyzing the leukocyte population by flow cytometry, monocytes and granulocytes in the peritoneal cavity, liver, spleen and bone marrow (BM) recovered faster than in the control group. The ratio of natural killer cells and gammadelta T cells in the liver, spleen and peritoneal cavity was also increased. In contrast, CD4+ CD8+ cells in the thymus were temporarily significantly decreased by the administration of SCG. Interleukin-6 (IL-6) production of CY+SCG-treated peritoneal exdated cells (PECs), spleen cells and bone marrow cells (BMCs) were higher than that of the CY-treated group. By in vitro culture of CY-treated PEC and spleen cells, IL-6 production was enhanced by the addition of SCG. These facts suggested the possibility that IL-6 might be a key cytokine for the enhanced hematopoietic response by SCG.

Juvenile wood effect in red alder : analysis of physical and mechanical data to delineate juvenile and mature wood zones

Treesearch

Joel W. Evans; John F. Senft; David W. Green

2000-01-01

The objective of this study was to investigate the influence of juvenile wood on the mechanical and physical properties of red alder. Tree growth in the first 10 to 20 years, usually referred to as juvenile wood, often influences wood quality by adversely affecting mechanical strength properties. Strength can be reduced up to 50 percent by the presence of juvenile wood...

Diels-Alder cycloaddition in the synthesis of 1-azafagomine, analogs, and derivatives as glycosidase inhibitors.

PubMed

Salgueiro, Daniela A L; Sousa, Cristina E A; Fortes, A Gil; Alves, M José

2012-12-01

This comprehensive review deals with the synthesis of 1-azafagomine, analogs, and derivatives having the Diels-Alder cycloaddition as the key step. Most of the compounds referred are racemic or have been resolved by lipase transesterification. There are two asymmetric cycloadditions leading to 1-azafagomine or to an analog. In one case both enantiomers of 1-azafagomine were prepared together with a pair of derivatives. The study comprises glycosidase inhibition studies of the target compounds to a set of glycosidic enzymes, and evidenced molecular features that enhance or diminish their activity as glycosidase inhibitors.

The Synthesis of "N"-Benzyl-2-Azanorbornene via Aqueous Hetero Diels-Alder Reaction: An Undergraduate Project in Organic Synthesis and Structural Analysis

ERIC Educational Resources Information Center

Sauvage, Xavier; Delaude, Lionel

2008-01-01

The synthesis of "N"-benzyl-2-azanorbornene via aqueous hetero Diels-Alder reaction of cyclopentadiene and benzyliminium chloride formed in situ from benzylamine hydrochloride and formaldehyde is described. Characterization of the product was achieved by IR and NMR spectroscopies. The spectral data acquired are thoroughly discussed. Numerous…

High-speed microwave-promoted hetero-Diels-Alder reactions of 2(1H)-pyrazinones in ionic liquid doped solvents.

PubMed

Van Der Eycken, Erik; Appukkuttan, Prasad; De Borggraeve, Wim; Dehaen, Wim; Dallinger, Doris; Kappe, C Oliver

2002-11-01

Inter- and intramolecular hetero-Diels-Alder reactions in a series of functionalized 2(1H)-pyrazinones were investigated under controlled microwave irradiation. The cycloaddition reactions were efficiently performed in sealed tubes, utilizing either a combination of 1,2-dichloroethane and a thermally stable ionic liquid, or 1,2-dichlorobenzene as reaction medium. In all cases, a significant rate-enhancement using microwave flash heating as compared to thermal heating was observed.

Diels-Alder Cycloadditions: A MORE Experiment in the Organic Laboratory Including a Diene Identification Exercise Involving NMR Spectroscopy and Molecular Modeling

ERIC Educational Resources Information Center

Shaw, Roosevelt; Severin, Ashika; Balfour, Miguel; Nettles, Columbus

2005-01-01

Two Diels-Alder reactions are described that are suitable for a MORE (microwave-induced organic reaction enhanced) experiment in the organic chemistry laboratory course. A second experiment in which the splitting patterns of the vinyl protons in the nuclear magnetic resonance (NMR) spectra of two MORE adducts are used in conjunction with molecular…

Domino Acylation/Diels-Alder Synthesis of N-Alkyl-octahydroisoquinolin-1-one-8-carboxylic Acids under Low-Solvent Conditions.

PubMed

Slauson, Stephen R; Pemberton, Ryan; Ghosh, Partha; Tantillo, Dean J; Aubé, Jeffrey

2015-05-15

The development of the domino reaction between an aminoethyl-substituted diene and maleic anhydride to afford an N-substituted octahydroisoquinolin-1-one is described. A typical procedure involves the treatment of a 1-aminoethyl-substituted butadiene with maleic anhydride at 0 °C to room temperature for 20 min under low-solvent conditions, which affords a series of isoquinolinone carboxylic acids in moderate to excellent yields. NMR monitoring suggested that the reaction proceeded via an initial acylation step followed by an intramolecular Diels-Alder reaction. For the latter step, a significant rate difference was observed depending on whether the amino group was substituted by a phenyl or an alkyl (usually benzyl) substituent, with the former noted by NMR to be substantially slower. The Diels-Alder step was studied by density functional theory (DFT) methods, leading to the conclusion that the degree of preorganization in the starting acylated intermediate had the largest effect on the reaction barriers. In addition, the effect of electronics on the aromatic ring in N-phenyl substrates was studied computationally and experimentally. Overall, this protocol proved considerably more amenable to scale up compared to earlier methods by eliminating the requirement of microwave batch chemistry for this reaction as well as significantly reducing the quantity of solvent.

Tyrosine-lipid peroxide adducts from radical termination: para coupling and intramolecular Diels-Alder cyclization.

PubMed

Shchepin, Roman; Möller, Matias N; Kim, Hye-young H; Hatch, Duane M; Bartesaghi, Silvina; Kalyanaraman, Balaraman; Radi, Rafael; Porter, Ned A

2010-12-15

Free radical co-oxidation of polyunsaturated lipids with tyrosine or phenolic analogues of tyrosine gave rise to lipid peroxide-tyrosine (phenol) adducts in both aqueous micellar and organic solutions. The novel adducts were isolated and characterized by 1D and 2D NMR spectroscopy as well as by mass spectrometry (MS). The spectral data suggest that the polyunsaturated lipid peroxyl radicals give stable peroxide coupling products exclusively at the para position of the tyrosyl (phenoxy) radicals. These adducts have characteristic (13)C chemical shifts at 185 ppm due to the cross-conjugated carbonyl of the phenol-derived cyclohexadienone. The primary peroxide adducts subsequently undergo intramolecular Diels-Alder (IMDA) cyclization, affording a number of diastereomeric tricyclic adducts that have characteristic carbonyl (13)C chemical shifts at ~198 ppm. All of the NMR HMBC and HSQC correlations support the structure assignments of the primary and Diels-Alder adducts, as does MS collision-induced dissociation data. Kinetic rate constants and activation parameters for the IMDA reaction were determined, and the primary adducts were reduced with cuprous ion to give a phenol-derived 4-hydroxycyclohexa-2,5-dienone. No products from adduction of peroxyls at the phenolic ortho position were found in either the primary or cuprous reduction product mixtures. These studies provide a framework for understanding the nature of lipid-protein adducts formed by peroxyl-tyrosyl radical-radical termination processes. Coupling of lipid peroxyl radicals with tyrosyl radicals leads to cyclohexenone and cyclohexadienone adducts, which are of interest in and of themselves since, as electrophiles, they are likely targets for protein nucleophiles. One consequence of lipid peroxyl reactions with tyrosyls may therefore be protein-protein cross-links via interprotein Michael adducts.

Tyrosine-Lipid Peroxide Adducts from Radical Termination: Para-Coupling and Intramolecular Diels-Alder Cyclization

PubMed Central

Shchepin, Roman; Möller, Matias N.; Kim, Hye-young H.; Hatch, Duane M.; Bartesaghi, Silvina; Kalyanaraman, Balaraman; Radi, Rafael

2013-01-01

Free radical co-oxidation of polyunsaturated lipids with tyrosine or phenolic analogs of tyrosine gave rise to lipid peroxide-tyrosine (phenol) adducts in both aqueous micellar and organic solutions. The novel adducts were isolated and characterized by 1D and 2D NMR as well as by mass spectrometry. The spectral data suggest that the polyunsaturated lipid peroxyl radicals give stable peroxide coupling products exclusively at the para position of the tyrosyl (phenoxy) radicals. These adducts have characteristic 13C chemical shifts at 185 ppm due to the cross-conjugated carbonyl of the phenol-derived cyclohexadienone. The primary peroxide adducts subsequently undergo intramolecular Diels-Alder (IMDA) cyclization, affording a number of diastereomeric tricyclic adducts that have characteristic carbonyl 13C chemical shifts at ~198 ppm. All NMR HMBC and HSQC correlations support the structure assignment of the primary and Diels-Alder adducts, as does MS collision induced dissociation. Kinetic rate constants and activation parameters for the IMDA reaction were determined and the primary adducts were reduced with cuprous ion giving a phenol-derived 4-hydroxycyclohexa-2,5-dienone. No products from adduction of peroxyls at the phenolic ortho position were found either in the primary or the cuprous reduction product mixtures. These studies provide a framework for understanding the nature of lipid-protein adducts formed by peroxyl-tyrosyl radical-radical termination processes. Coupling of lipid peroxyl radicals with tyrosyl radicals leads to cyclohexenone and cyclohexadienone adducts which are of interest in and of themselves since, as electrophiles, they are likely targets for protein nucleophiles. One consequence of lipid peroxyl reactions with tyrosyls may therefore be protein-protein crosslinks via interprotein Michael adducts. PMID:21090613

Selection of ribozymes that catalyse multiple-turnover Diels–Alder cycloadditions by using in vitro compartmentalization

PubMed Central

Agresti, Jeremy J.; Kelly, Bernard T.; Jäschke, Andres; Griffiths, Andrew D.

2005-01-01

In vitro compartmentalization (IVC) has previously been used to evolve protein enzymes. Here, we demonstrate how IVC can be applied to select RNA enzymes (ribozymes) for a property that has previously been unselectable: true intermolecular catalysis. Libraries containing 1011 ribozyme genes are compartmentalized in the aqueous droplets of a water-in-oil emulsion, such that most droplets contain no more than one gene, and transcribed in situ. By coencapsulating the gene, RNA, and the substrates/products of the catalyzed reaction, ribozymes can be selected for all enzymatic properties: substrate recognition, product formation, rate acceleration, and turnover. Here we exploit the complementarity of IVC with systematic evolution of ligands by exponential enrichment (SELEX), which allows selection of larger libraries (≥1015) and for very small rate accelerations (kcat/kuncat) but only selects for intramolecular single-turnover reactions. We selected ≈1014 random RNAs for Diels–Alderase activity with five rounds of SELEX, then six to nine rounds with IVC. All selected ribozymes catalyzed the Diels–Alder reaction in a truly bimolecular fashion and with multiple turnover. Nearly all ribozymes selected by using eleven rounds of SELEX alone contain a common catalytic motif. Selecting with SELEX then IVC gave ribozymes with significant sequence variations in this catalytic motif and ribozymes with completely novel motifs. Interestingly, the catalytic properties of all of the selected ribozymes were quite similar. The ribozymes are strongly product inhibited, consistent with the Diels–Alder transition state closely resembling the product. More efficient Diels–Alderases may need to catalyze a second reaction that transforms the product and prevents product inhibition. PMID:16260754

Microwave-Assisted Organocatalytic Intramolecular Knoevenagel/Hetero Diels-Alder Reaction with O-(Arylpropynyloxy)-Salicylaldehydes: Synthesis of Polycyclic Embelin Derivatives.

PubMed

Martín-Acosta, Pedro; Feresin, Gabriela; Tapia, Alejandro; Estévez-Braun, Ana

2016-10-21

A highly efficient and regioselective approach to new polycyclic embelin derivatives through a domino Knoevenagel condensation/intramolecular hetero Diels-Alder reaction using O-(arylpropynyloxy)-salicylaldehydes in the presence of ethylenediamine diacetate (EDDA) is reported. This organocatalyzed protocol is compatible toward a wide range of aryl-substituted alkynyl ethers with electron-donating and electron-withdrawing groups. When other active methylene compounds were subjected to this domino reaction the corresponding adducts were obtained in high yield.

Red Alder (Alnus rubra) Distribution Influences Nitrate Discharge to Coastal Estuaries: Comparison of Two Oregon Watersheds

EPA Science Inventory

We determined nutrient export from the Yaquina and Alsea Rivers as part of a larger program for evaluating nutrient sources to coastal waters. The Yaquina and Alsea data indicated that one river typically contained twice the amount of dissolved nitrate-N, although temperature, co...

Microcontact Printing Patterning of an HOPG Surface by an Inverse Electron Demand Diels-Alder Reaction.

PubMed

Zhu, Jun; Hiltz, Jonathan; Tefashe, Ushula M; Mauzeroll, Janine; Lennox, R Bruce

2018-06-21

The chemical modification of an sp 2 hybridized carbon surface in a controllable manner is very challenging but also crucial for many applications. An inverse electron demand Diels-Alder (IEDDA) reaction using microcontact printing technique is introduced to spatially control the modification of a highly ordered pyrolytic graphite (HOPG) surface under ambient conditions. The covalent modification was characterized by Raman spectroscopy, XPS, and SECM. Tetrazine derivatives can effectively react with an HOPG surface and with microcontact printing methods resulting in spatially patterned surfaces being produced with micrometer-scale resolution. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Diels–Alder Reactions of Allene with Benzene and Butadiene: Concerted, Stepwise, and Ambimodal Transition States

PubMed Central

2015-01-01

Multiconfigurational complete active space methods (CASSCF and CASPT2) have been used to investigate the (4 + 2) cycloadditions of allene with butadiene and with benzene. Both concerted and stepwise radical pathways were examined to determine the mechanism of the Diels–Alder reactions with an allene dienophile. Reaction with butadiene occurs via a single ambimodal transition state that can lead to either the concerted or stepwise trajectories along the potential energy surface, while reaction with benzene involves two separate transition states and favors the concerted mechanism relative to the stepwise mechanism via a diradical intermediate. PMID:25216056

Paleoecological studies at Lake Patzcuaro on the west-central Mexican Plateau and at Chalco in the basin of Mexico

USGS Publications Warehouse

Watts, W.A.; Bradbury, J.P.

1982-01-01

A 1520-cm sediment core from Lake Patzcuaro, Michoacan, Mexico, is 44,000 yr old at the base. All parts of the core have abundant pollen of Pinus (pine), Alnus (alder), and Quercus (oak) with frequent Abies (fir). The interval dated from 44,000 to 11,000 yr ago has a homogeneous flora characterized by abundant Juniperus (juniper) pollen and frequent Artemisia (sagebrush). It is believed to represent an appreciably drier and colder climate than at present. The Holocene at Lake Patzcuaro is characterized by a moderate increase in Pinus pollen and the loss of Juniperus pollen, as the modern type of climate succeeded. Alnus was abundant until about 5000 yr ago; its abrupt decrease with the first appearance of herbaceous weed pollen may reflect the cutting of lake-shore and stream-course alder communities for agricultural purposes, or it may simply reflect a drying tendency in the climate. Pollen of Zea (corn) appears at Lake Patzcuaro along with low peaks of chenopod and grass pollen at 3500 yr B.P. apparently recording a human population large enough to modify the natural environment, as well as the beginning of agriculture. A rich aquatic flora in this phase suggests eutrophication of the lake by slope erosion. In the most recent period corn is absent from the sediments, perhaps reflecting a change in agricultural practices. The environment changes at Lake Patzcuaro are similar to and correlate with those in the Cuenca de Mexico, where diatom stratigraphy from the Chalco basin indicates fluctuations in lake levels and lake chemistry in response to variations in available moisture. Before 10,000 yr ago climates there were cool and dry, and the Chalco basin was occupied by a shallow freshwater marsh that drained north to Lake Texcoco, where saline water accumulated by evaporation. Increases in effective moisture and possible melting of glaciers during the Holocene caused lake levels to rise throughout the Cuenca de Mexico, and Lake Texcoco flooded the Chalco basin with

Grafting methyl acrylic onto carbon fiber via Diels-Alder reaction for excellent mechanical and tribological properties of phenolic composites

NASA Astrophysics Data System (ADS)

Fei, Jie; Duan, Xiao; Luo, Lan; Zhang, Chao; Qi, Ying; Li, Hejun; Feng, Yongqiang; Huang, Jianfeng

2018-03-01

Carbon fibers (CFs) were grafted with methyl acrylic via Diels-Alder reaction at the different oil bath temperature effectively creating a carboxyl functionalized surface. The effect of grafting temperature on the surface morphology and functional groups of carbon fibers were investigated by FTIR, Raman spectroscopy, XPS and SEM respectively. The results showed that the optimal grafting temperature was 80 °C, and the relative surface coverage by carboxylic acid groups increased from an initial 5.16% up to 19.30% significantly improved the chemical activity without damaging the skin and core region of the carbon fibers. Mechanical property tests indicated that the shear and tensile strength of the sample with the grafting temperature of 80 °C (CFRP-3) increased obviously by 90.3% and 78.7%, respectively, compared with the pristine carbon fibers reinforced composite. Further, the sample CFRP-3 exhibited higher and more stable friction coefficient and improved wear resistance, while the wear rate decreased 52.7%, from 10.8 × 10-6 to 5.1 × 10-6 mm3/N m. The present work shows that grafting methyl acrylic via Diels-Alder reaction could be a highly efficient and facile method to functionalize carbon fibers for advanced composites.

Diels-Alder addition to H2O@C60 an electronic and structural study

NASA Astrophysics Data System (ADS)

Reveles, J. Ulises; Govinda, K. C.; Baruah, Tunna; Zope, Rajendra R.

2017-10-01

Exohedral reactivity of endohedral fullerenes has aroused a significant interest because of its potential applications. The present letter examines the effect of an entrapped single water molecule on the reactivity of C60. We study the thermodynamics and kinetics of a Diels-Alder reaction occurring at all non-identical bonds of free C60 and H2O@C60. Our calculations show that encapsulation of water does not have a significant effect on H2O@C60 reactivity compared to C60, as attested by the investigation of the reaction under several orientations of H2O inside C60. Reaction and activation energies indicate that [6,6] bonds are the most reactive sites.

Syntheses of the hexahydroindene cores of indanomycin and stawamycin by combinations of iridium-catalyzed asymmetric allylic alkylations and intramolecular Diels-Alder reactions.

PubMed

Gärtner, Martin; Satyanarayana, Gedu; Förster, Sebastian; Helmchen, Günter

2013-01-02

Short and concise syntheses of the hexahydroindene cores of the antibiotics indanomycin (X-14547 A) and stawamycin are presented. Key methods used are an asymmetric iridium-catalyzed allylic alkylation, a modified Julia olefination, a Suzuki-Miyaura coupling, and an intramolecular Diels-Alder reaction. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of cyclopentadienyl capped polyethylene and subsequent block copolymer formation via hetero Diels-Alder (HDA) chemistry.

PubMed

Espinosa, Edgar; Glassner, Mathias; Boisson, Christophe; Barner-Kowollik, Christopher; D'Agosto, Franck

2011-09-15

In the current contribution it is demonstrated - for the first time - that poly(ethylene) (M(n) = 1,400 as well as 2,800 g  ·  mol(-1) , PDI = 1.2) can be readily equipped with highly reactive cyclopentadienyl (Cp) end groups. The Cp terminal poly(ethylene) can subsequently be reacted in an efficient hetero Diels-Alder (HDA) reaction with macromolecules (poly(isobornyl acrylate) (M(n) = 4,600 g  ·  mol(-1) , PDI = 1.10) and poly(styrene) (M(n) = 6,300 g  ·  mol(-1) , PDI = 1.13) featuring strongly electron withdrawing thiocarbonyl thio end groups, prepared via reversible addition fragmentation chain transfer (RAFT) polymerization employing benzylpyridin-2-yldithioformate (BPDF) as transfer agent. The resulting block copolymers have been analyzed via high-temperature size exclusion chromatography (SEC) as well as nuclear magnetic resonance (NMR) spectroscopy. The current system allows for the removal of the excess of the non-poly(ethylene) containing segment via filtration of the poly(ethylene)-containing block copolymer. However, the reaction temperatures need to be judiciously selected. Characterization of the generated block copolymers at elevated temperatures can lead - depending on the block copolymer type - to the occurrence of retro Diels-Alder processes. The present study thus demonstrates that RAFT-HDA ligation can be effectively employed for the generation of block copolymers containing poly(ethylene) segments. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of Pyrrolo[1,2-a]pyrimidine Enantiomers via Domino Ring-Closure followed by Retro Diels-Alder Protocol.

PubMed

Fekete, Beáta; Palkó, Márta; Haukka, Matti; Fülöp, Ferenc

2017-04-13

From 2-aminonorbornene hydroxamic acids, a simple and efficient method for the preparation of pyrrolo[1,2- a ]pyrimidine enantiomers is reported. The synthesis is based on domino ring-closure followed by microwave-induced retro Diels-Alder (RDA) protocols, where the chirality of the desired products is transferred from norbornene derivatives. The stereochemistry of the synthesized compounds was proven by X-ray crystallography. The absolute configuration of the product is determined by the configuration of the starting amino hydroxamic acid.

Isoprene/methyl acrylate Diels-Alder reaction in supercritical carbon dioxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, B.; Akgerman, A.

1999-12-01

The Diels-Alder reaction between isoprene and methyl acrylate was carried out in supercritical carbon dioxide in the temperature range 110--140 C and the pressure range 95.2--176.9 atm in a 300 cm{sup 3} autoclave. The high-pressure phase behavior of the reaction mixture in the vicinity of its critical region was determined in a mixed vessel with a sight window to ensure that all the experiments were performed in the supercritical single-phase region. Kinetic data were obtained at different temperatures, pressures, and reaction times. It was observed that in the vicinity of the critical point the reaction rate constant decreases with increasingmore » pressure. It was also determined that the reaction selectivity does not change with operating conditions. Transition-state theory was used to explain the effect of pressure on reaction rate and product selectivity. Additional experiments were conducted at constant temperature but different phase behaviors (two-phase region, liquid phase, supercritical phase) by adjusting the initial composition and pressure. It was shown that the highest reaction rate is in the supercritical region.« less

Fluorogenic Behaviour of the Hetero-Diels-Alder Ligation of 5-Alkoxyoxazoles with Maleimides and their Applications.

PubMed

Renault, Kévin; Jouanno, Laurie-Anne; Lizzul-Jurse, Antoine; Renard, Pierre-Yves; Sabot, Cyrille

2016-12-19

Fluorogenic reactions are largely underrepresented in the toolbox of chemoselective ligations despite their tremendous potential, particularly in chemical biology and biochemistry. In this respect, we have investigated in full detail the fluorescence behaviour of the azaphthalamide, a scaffold which is generated through a hetero-Diels-Alder reaction of 5-alkoxyoxazole and maleimide derivatives under mild conditions that are compatible with, among others, peptide chemistry. The scope and limitations of such a fluorogenic labelling strategy were examined through four distinct applications, which target enzymatic activities or bioorthogonal reactions. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Assessing the superelectrophilic dimension through sigma-complexation, SNAr and Diels-Alder reactivity.

PubMed

Buncel, Erwin; Terrier, François

2010-05-21

In the domain of organic chemistry, S(N)Ar substitutions represent a class of reactions of overwhelming importance, both in synthesis and in the understanding of structure-reactivity relationships, especially the role of sigma-complex intermediates. The primary factor necessary for achievement of S(N)Ar reactions is the presence of a good leaving group, which allows facile rearomatization of the ring undergoing nucleophilic attack. Consistent is the finding that the superelectrophilic chloronitrobenzofuroxans--or furazans--exhibit a very high S(N)Ar reactivity, allowing a number of C-C, C-N, C-O couplings to be achieved that are not accessible with the classical series of nitro-substituted aromatics. Of particular interest is the synthesis of a number of indoles, indolizines, pyrroles and extended pi-excessive aromatic structures like azulene substituted by superelectrophilic moieties. The remarkable driving force for the facile completion of these reactions is the 10 orders of magnitude greater reactivity of 10pi-electron-deficient heteroaromatics such as 4,6-dinitrobenzofuroxan (DNBF) than of the most reactive trinitrobenzene derivatives in sigma-adduct complexation. Among the factors that have been recognized as governing superelectrophilicity, there is the poor aromaticity of 6-membered 10pi-electron structures investigated, with a common origin for sigma-complexation and pericyclic processes. A remarkable capacity of these structures is actually to contribute to a variety of Diels-Alder reactions. As an example, the DNBF molecule formally behaves as a nitroalkene, being susceptible to act as a dienophile as well as a heterodiene. Another remarkable Diels-Alder pathway is the capacity of the 6-membered carbocyclic ring of DNBF to act as a carbodiene. Also noteworthy is the successful Diels-Alder trapping of the dinitroso intermediate associated with 1-oxide/3-oxide tautomerism of the furoxan moiety of 4-aza-6-nitrobenzofuroxan. A point of fundamental importance

Solid-supported nitroso hetero Diels-Alder reactions. 1. Acylnitroso dienophiles: scope and limitations.

PubMed

Krchnák, Viktor; Moellmann, Ute; Dahse, Hans-Martin; Miller, Marvin J

2008-01-01

Polymer-supported acylnitroso dienophiles were prepared and used in hetero Diels-Alder (HDA) reactions with a variety of dienes. The transient acylnitroso dienophiles were prepared in situ from immobilized hydroxamates, which were attached to solid supports via several linkers each cleavable by different cleavage reagents, and served for the synthesis of both N-unsubstituted and N-derivatized HDA adducts. Model compounds were used to (i) optimize reaction conditions for solid-supported HDA reactions, (ii) evaluate the outcome of the reactions with various dienes, (iii) compare relative reactivities of dienes, and (iv) assess the stability of HDA adducts toward cleavage conditions typically used in solid-phase syntheses. Cleaved products were submitted to biological assays, and the results are reported. The accompanying paper, focused on complementary arylnitroso HDA reactions, includes a comparison of both HDA reactions.

Noteworthy habitat and phylogeny updates for eastern US Ulota (Orthotrichaceae, Bryophyta).

PubMed

Tessler, Michael; Cunningham, Seth W; Clark, Theresa A

2017-09-01

The moss Ulota crispa is ubiquitous as an obligate epiphyte in eastern North America. Yet several specimens preliminarily identified as U. crispa were collected from the upper portions of boulders in the Shawangunks, NY. Mitochondrial (nad5) and chloroplast (rps4 and trnL-trnF) sequence data were produced for these specimens, confirming their status as the first record of rock-dwelling U. crispa in North America. The reviewed loci were then used to assess phylogenetic relationships of Northeastern US Ulota species, incorporating a species not yet reviewed, U. coarctata. Conforming to peristome morphology, Ulota hutchinsiae appears to be more closely related to U. crispa than to U. coarctata. Monophyly was recovered for U. crispa and U. coarctata. Although monophyly was not found for U. hutchinsiae, it is diagnosably distinct based on the reviewed loci. While almost identical in number of nucleotides sequenced, mitochondrial DNA held substantially less phylogenetically informative nucleotides than the chloroplast loci, but did have important indel information segregating U. coarctata from other species reviewed.

Stereoselective protecting group free synthesis of D,L-gulose ethyl glycoside via multicomponent enyne cross metathesis--hetero Diels-Alder reaction.

PubMed

Castagnolo, Daniele; Botta, Lorenzo; Botta, Maurizio

2009-07-27

An efficient and stereoselective synthesis of D,L-gulose was described. The key step of the synthetic route is represented by a multicomponent enyne cross metathesis-hetero Diels-Alder reaction which allows the formation of the pyran ring from cheap and commercially available substrates in a single synthetic step. The synthesis of D,L-gulose was accomplished without the use of protecting groups making this approach highly desirable also in terms of atom economy.

Oxidative Processing Lowers the Ice Nucleation Activity of Birch and Alder Pollen

NASA Astrophysics Data System (ADS)

Gute, Ellen; Abbatt, Jonathan P. D.

2018-02-01

Pollen carry water extractable compounds with ice nucleating (IN) activity. This study investigates whether the hydroxyl radical, as the major atmospheric oxidant, can affect the IN activity of silver birch and grey alder subpollen particles under in-cloud conditions for deposition freezing mode conditions at 234 K. It is found that oxidation increases the supersaturation ratio with respect to ice necessary for the onset of ice nucleation and decreases the fraction of particles which initiate ice nucleation. This reduction of IN activity under equivalent oxidation conditions does not occur with a mineral dust sample (Arizona Test Dust). Chemical analysis of fresh and oxidized pollen material indicates a change of molecular structure with a loss of conjugation and an increase in oxidized functional groups, such as carbonyls. This is the first demonstration that in-cloud oxidation may lower the IN abilities of biological particles such as pollen.

Preparative isolation and purification of antioxidative diarylheptanoid derivatives from Alnus japonica by high-speed counter-current chromatography.

PubMed

Lim, Soon Sung; Lee, Min Young; Ahn, Hong Ryul; Choi, Soon Jung; Lee, Jae-Yong; Jung, Sang Hoon

2011-12-01

This study employed the online HPLC-2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS)(+) bioassay to rapidly determine the antioxidant compounds occurring in the crude extract of Alnus japonica. The negative peaks of the ABTS(+) radical scavenging detection system, which indicated the presence of antioxidant activity, were monitored by measuring the decrease in absorbance at 734 nm. The ABTS(+)-based antioxidant activity profile showed that three negative peaks exhibited antioxidant activity. High-speed counter-current chromatography (HSCCC) was used for preparative scale separation of the three active peaks from the extract. The purity of the isolated compounds was analyzed by HPLC and their structures were identified by (1)H- and (13)C-nuclear magnetic resonance spectrometry (NMR), heteronuclear multiple bond correlation (HMBC), and heteronuclear single quantum correlation (HSQC). Two solvent systems composed of n-hexane/ethylacetate/methanol/water (4:6:4:6, v/v) and of ethyl acetate/methanol/water (1:0.1:1, v/v) were performed in high-speed counter-current chromatography. Consequently, a total of 527 mg of hirsutanonol 5-O-β-D-glucopyranoside, 80.04 mg of 3-deoxohirsutenonol 5-O-β-D-glucopyranoside, and 91.0 mg of hirsutenone were obtained with purity of 94.7, 90.5, and 98.6%, respectively. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High Genetic Diversity and Distinctiveness of Rear-Edge Climate Relicts Maintained by Ancient Tetraploidisation for Alnus glutinosa

PubMed Central

Lepais, Olivier; Muller, Serge D.; Ben Saad-Limam, Samia; Benslama, Mohamed; Rhazi, Laila; Belouahem-Abed, Djamila; Daoud-Bouattour, Amina; Gammar, Amor Mokhtar; Ghrabi-Gammar, Zeineb; Bacles, Cécile Fanny Emilie

2013-01-01

Populations located at the rear-edge of a species’ distribution may have disproportionate ecological and evolutionary importance for biodiversity conservation in a changing global environment. Yet genetic studies of such populations remain rare. This study investigates the evolutionary history of North-African low latitude marginal populations of Alnus glutinosa Gaertn., a European tree species that plays a significant ecological role as a keystone of riparian ecosystems. We genotyped 551 adults from 19 populations located across North Africa at 12 microsatellite loci and applied a coalescent-based simulation approach to reconstruct the demographic and evolutionary history of these populations. Surprisingly, Moroccan trees were tetraploids demonstrating a strong distinctiveness of these populations within a species otherwise known as diploid. Best-fitting models of demographic reconstruction revealed the relict nature of Moroccan populations that were found to have withstood past climate change events and to be much older than Algerian and Tunisian populations. This study highlights the complex demographic history that can be encountered in rear-edge distribution margins that here consist of both old stable climate relict and more recent populations, distinctively diverse genetically both quantitatively and qualitatively. We emphasize the high evolutionary and conservation value of marginal rear-edge populations of a keystone riparian species in the context of on-going climate change in the Mediterranean region. PMID:24098677

Irreversible endo-Selective Diels–Alder Reactions of Substituted Alkoxyfurans: A General Synthesis of endo-Cantharimides

PubMed Central

Foster, Robert W; Benhamou, Laure; Porter, Michael J; Bučar, Dejan-Krešimir; Hailes, Helen C; Tame, Christopher J; Sheppard, Tom D

2015-01-01

The [4+2] cycloaddition of 3-alkoxyfurans with N-substituted maleimides provides the first general route for preparing endo-cantharimides. Unlike the corresponding reaction with 3H furans, the reaction can tolerate a broad range of 2-substitued furans including alkyl, aromatic, and heteroaromatic groups. The cycloaddition products were converted into a range of cantharimide products with promising lead-like properties for medicinal chemistry programs. Furthermore, the electron-rich furans are shown to react with a variety of alternative dienophiles to generate 7-oxabicyclo[2.2.1]heptane derivatives under mild conditions. DFT calculations have been performed to rationalize the activation effect of the 3-alkoxy group on a furan Diels–Alder reaction. PMID:25756502

Role of genetic improvement in the Short Rotation Woody Crops Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Layton, P.A.; Wright, L.L.

1986-01-01

A major effort in the Short Rotation Woody Crops Program (SRWCP) is species screening and genetic improvement of selected species. Of the 125 species initially evaluated for SRIC, 20 are being seriously considered with most of emphasis on 16 hardwood species. Range-wide seed collections of 12 species were provenance tested; these include Platanus occidentalis (sycamore), Alnus glutinosa (European black alder), and Robinia pseudoacacia (black locust). Based on the results of these tests, highly productive, site-specific seed sources are being chosen for several geographic regions. Three of these species re currently being bred for increased productivity in SRIC systems. Genetic improvementmore » is viewed as a tool for increasing productivity, having anticipated gains of 40 to 50%. The techniques of somaclonal screening and genetic engineering are being evaluated for their usefulness in the SRIC improvement program. Currently, salt-tolerant Atriplex canescens (four-wing saltbush) and herbicide-resistant Populus spp. are being sought via somaclonal screening. 35 refs., 4 figs., 3 tabs.« less

Comparison of planted soil infiltration systems for treatment of log yard runoff.

PubMed

Hedmark, Asa; Scholz, Miklas; Aronsson, Par; Elowson, Torbjorn

2010-07-01

Treatment of log yard runoff is required to avoid contamination of receiving watercourses. The research aim was to assess if infiltration of log yard runoff through planted soil systems is successful and if different plant species affect the treatment performance at a field-scale experimental site in Sweden (2005 to 2007). Contaminated runoff from the log yard of a sawmill was infiltrated through soil planted with Alnus glutinosa (L.) Gärtner (common alder), Salix schwerinii X viminalis (willow variety "Gudrun"), Lolium perenne (L.) (rye grass), and Phalaris arundinacea (L.) (reed canary grass). The study concluded that there were no treatment differences when comparing the four different plants with each other, and there also were no differences between the tree and the grass species. Furthermore, the infiltration treatment was effective in reducing total organic carbon (55%) and total phosphorus (45%) concentrations in the runoff, even when the loads on the infiltration system increased from year to year.

Woodcock singing-ground counts and habitat changes in the northeastern United States

USGS Publications Warehouse

Dwyer, T.J.; McAuley, D.G.; Derleth, E.L.

1983-01-01

Aerial photography from the late 1960's and the late 1970's was used to study habitat changes along 78 American woodcock (Scolopax minor) singing-ground routes in 9 northeastern states. The most noticeable changes were declines in the amount of abandoned field, cropland, shrubland, and field/pasture. The amount of land in the urban/industrial type increased 33.4% from the late 1960's to the late 1970's. We examined relationships between the woodcock call-count index and habitat variables using multiple-regression techniques. The abundance of calling male woodcock was positively correlated with the amount of abandoned field and alder (Alnus sp.) and negatively correlated with the amount of urban/industrial type. However, only the change in the urban/industrial type was significantly (P < 0.05) related to the change in the call-count index. Urban/industrial area increased, whereas the call-count index declined on average in our sample of routes by 1.4 birds/route (40.5%).

Diastereoselective Diels-Alder reactions of alpha-fluorinated alpha,beta-unsaturated carbonyl compounds: chemical consequences of fluorine substitution. 2.

PubMed

Essers, Michael; Mück-Lichtenfeld, Christian; Haufe, Günter

2002-07-12

Two alpha-fluoro alpha,beta-unsaturated carbonyl compounds, i.e., benzyl 2-fluoroacrylate (3) and 2-fluorooct-1-en-3-one (4), as well as the corresponding nonfluorinated parent compounds, were synthesized and subjected to Diels-Alder reactions with cyclopentadiene. The cycloadditions were conducted thermally, microwave-assisted, and Lewis acid-mediated (TiCl(4)). The fluorinated dienophiles exhibited a lower reactivity and exo diastereoselectivity, while the corresponding nonfluorinated parent compounds reacted endo selectively. DFT calculations suggest that kinetic effects of fluorine determine the stereoselectivity rather than higher thermodynamic stability of the exo products.

Chlorotheolides A and B, Spiroketals Generated via Diels-Alder Reactions in the Endophytic Fungus Pestalotiopsis theae.

PubMed

Liu, Ling; Han, Yu; Xiao, Junhai; Li, Li; Guo, Liangdong; Jiang, Xuejun; Kong, Lingyi; Che, Yongsheng

2016-10-28

Chlorotheolides A (1) and B (2), two new spiroketals possessing the unique [4,7]methanochromene and dispiro-trione skeletons, respectively, and their putative biosynthetic precursors, 1-undecen-2,3-dicarboxylic acid (3) and maldoxin (4), were isolated from the solid substrate fermentation of the plant endophytic fungus Pestalotiopsis theae (N635). Their structures were elucidated based on NMR spectroscopic data and electronic circular dichroism calculations. Biogenetically, compounds 1 and 2 could be generated from the co-isolated 3 and 4 via Diels-Alder reactions. Chlorotheolide (2) showed an antiproliferative effect against the human tumor cell line HeLa and induced an autophagic process in the cells.

Recyclable thermosetting thermal pad using silicone-based polyurethane crosslinked by Diels-Alder adduct

NASA Astrophysics Data System (ADS)

Kim, Jong-Woong; Lee, Da Hee; Jeon, Hee-Jeong; Jang, Sung Il; Cho, Hyun Min; Kim, Youngmin

2018-01-01

The recyclable silicone-based thermoset was successfully synthesized by making use of a Diels-Alder (DA) adduct as a cross-linker. The incorporation of the furan-tethered diol 1 into the polymer backbones realized the crosslinking of polymers via the DA reaction. The thermosetting polymer was dissolved in DMF after the retro DA reaction which was monitored by 1H NMR spectroscopy. Due to the retro DA reaction, polymer showed the mendable behavior when it was scratched followed by being heated. This polymer was mixed with alumina powders to fabricate the thermal pad. The thermal resistance of this pad was measured to be 0.48 K/W by a thermal transient test. The thermosetting composite was recycled via the retro DA reaction. The thermal resistance of the recycled one was similar to that of the original one.

Bio-orthogonal Fluorescent Labelling of Biopolymers through Inverse-Electron-Demand Diels-Alder Reactions.

PubMed

Kozma, Eszter; Demeter, Orsolya; Kele, Péter

2017-03-16

Bio-orthogonal labelling schemes based on inverse-electron-demand Diels-Alder (IEDDA) cycloaddition have attracted much attention in chemical biology recently. The appealing features of this reaction, such as the fast reaction kinetics, fully bio-orthogonal nature and high selectivity, have helped chemical biologists gain deeper understanding of biochemical processes at the molecular level. Listing the components and discussing the possibilities and limitations of these reagents, we provide a recent snapshot of the field of IEDDA-based biomolecular manipulation with special focus on fluorescent modulation approaches through the use of bio-orthogonalized building blocks. At the end, we discuss challenges that need to be addressed for further developments in order to overcome recent limitations and to enable researchers to answer biomolecular questions in more detail. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Synthesis of a Self-Healing Polymer Based on Reversible Diels-Alder Reaction: An Advanced Undergraduate Laboratory at the Interface of Organic Chemistry and Materials Science

ERIC Educational Resources Information Center

Weizman, Haim; Nielsen, Christian; Weizman, Or S.; Nemat-Nasser, Sia

2011-01-01

This laboratory experiment exposes students to the chemistry of self-healing polymers based on a Diels-Alder reaction. Students accomplish a multistep synthesis of a monomer building block and then polymerize it to form a cross-linked polymer. The healing capability of the polymer is verified by differential scanning calorimetry (DSC) experiments.…

Excellent acceleration of the Diels-Alder reaction by microwave irradiation for the synthesis of new fluorine-substituted ligands of NMDA receptor.

PubMed

Sasaki, S; Ishibashi, N; Kuwamura, T; Sano, H; Matoba, M; Nisikawa, T; Maeda, M

1998-11-03

A series of 6,11-ethanobenzo[b]quinolizinium derivatives was synthesized through the Diels-Alder reaction between azoniaanthracne and the corresponding 1,1-disubstituted olefin. After a systematic investigation for achieving rapid synthesis, it was found that the reaction is accelerated in polar media such as H2O and trifluoroethanol. In particular, excellent acceleration was effected by microwave irradiation. The new fluorine-substituted ligands thus obtained exhibited potential affinity toward NMDA receptors.

Theoretical study of Diels-Alder cycloadditions of butadiene to C{sub 70}. An insight into the chemical reactivity of C{sub 70} as compared to C{sub 60}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mestres, J.; Duran, M.; Sola, M.

1996-05-02

The eight unique Diels-Alder cycloadditions of butadiene to C{sub 70} are analyzed theoretically and compared with the well-established, two possible Diels-Alder cycloadditions of butadiene to C{sub 60}. Full geometry optimizations of reactants, adducts, and transition states are performed using the AMI semiempirical method followed by single-point ab initio energy calculations. The results show that the cycloaddition of butadiene to the C{sub 70} fullerene in the gas phase is slightly more reactive than that to C{sub 60}. However, in toluene solution calculations yield that the different solvent effects on C{sub 60} and C{sub 70} cause a significant decrease of the energymore » barrier in the C{sub 60} cycloaddition, thus predicting a larger reactivity for C{sub 60} as compared to the C{sub 70} fullerene. 36 refs., 2 figs., 3 tabs.« less

Diels-Alder active-template synthesis of rotaxanes and metal-ion-switchable molecular shuttles.

PubMed

Crowley, James D; Hänni, Kevin D; Leigh, David A; Slawin, Alexandra M Z

2010-04-14

A synthesis of [2]rotaxanes in which Zn(II) or Cu(II) Lewis acids catalyze a Diels-Alder cycloaddition to form the axle while simultaneously acting as the template for the assembly of the interlocked molecules is described. Coordination of the Lewis acid to a multidentate endotopic 2,6-di(methyleneoxymethyl)pyridyl- or bipyridine-containing macrocycle orients a chelated dienophile through the macrocycle cavity. Lewis acid activation of the double bond causes it to react with an incoming "stoppered" diene, affording the [2]rotaxane in up to 91% yield. Unusually for an active-template synthesis, the metal binding site "lives on" in these rotaxanes. This was exploited in the synthesis of a molecular shuttle containing two different ligating sites in which the position of the macrocycle could be switched by complexation with metal ions [Zn(II) and Pd(II)] with different preferred coordination geometries.

Elucidation of Diels-Alder Reaction Network of 2,5-Dimethylfuran and Ethylene on HY Zeolite Catalyst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Do, Phuong T. M.; McAtee, Jesse R.; Watson, Donald A.

2012-12-12

The reaction of 2,5-dimethylfuran and ethylene to produce p-xylene represents a potentially important route for the conversion of biomass to high-value organic chemicals. Current preparation methods suffer from low selectivity and produce a number of byproducts. Using modern separation and analytical techniques, the structures of many of the byproducts produced in this reaction when HY zeolite is employed as a catalyst have been identified. From these data, a detailed reaction network is proposed, demonstrating that hydrolysis and electrophilic alkylation reactions compete with the desired Diels–Alder/dehydration sequence. This information will allow the rational identification of more selective catalysts and more selectivemore » reaction conditions.« less

Inverse electron demand Diels-Alder reactions in chemical biology.

PubMed

Oliveira, B L; Guo, Z; Bernardes, G J L

2017-08-14

The emerging inverse electron demand Diels-Alder (IEDDA) reaction stands out from other bioorthogonal reactions by virtue of its unmatchable kinetics, excellent orthogonality and biocompatibility. With the recent discovery of novel dienophiles and optimal tetrazine coupling partners, attention has now been turned to the use of IEDDA approaches in basic biology, imaging and therapeutics. Here we review this bioorthogonal reaction and its promising applications for live cell and animal studies. We first discuss the key factors that contribute to the fast IEDDA kinetics and describe the most recent advances in the synthesis of tetrazine and dienophile coupling partners. Both coupling partners have been incorporated into proteins for tracking and imaging by use of fluorogenic tetrazines that become strongly fluorescent upon reaction. Selected notable examples of such applications are presented. The exceptional fast kinetics of this catalyst-free reaction, even using low concentrations of coupling partners, make it amenable for in vivo radiolabelling using pretargeting methodologies, which are also discussed. Finally, IEDDA reactions have recently found use in bioorthogonal decaging to activate proteins or drugs in gain-of-function strategies. We conclude by showing applications of the IEDDA reaction in the construction of biomaterials that are used for drug delivery and multimodal imaging, among others. The use and utility of the IEDDA reaction is interdisciplinary and promises to revolutionize chemical biology, radiochemistry and materials science.

Effect of Sasa veitchii extract on immunostimulating activity of β-glucan (SCG) from culinary-medicinal mushroom Sparassis crispa Wulf.:Fr. (higher Basidiomycetes).

PubMed

Yoshida, Mia; Hida, Toshie H; Takeshita, Kazuo; Tsuboi, Masamichi; Kanamori, Masato; Akachi, Natsuko; Miura, Noriko N; Adachi, Yoshiyuki; Ohno, Naohito

2012-01-01

Fungal β-glucan is a representative pathogen-associated microbial pattern (PAMP) from mushroom, yeast, and fungi, and stimulates innate as well as acquired immune systems. It is a widely used functional food to enhance immunity. Such plant extracts have been known as folk medicines and reported to show various biological activities beneficial to human health, such as anti-tumor, anti-allergic, and anti-inflammatory activities. In the present study, the cooperative effect of bamboo water-soluble methanol precipitation (BWMP), a macromolecular fraction of the hot-water extract of Sasa veitchii (Japanese folk medicine Kumazasa), and the β-glucan from the medicinal mushroom Sparassis crispa (SCG) was analyzed in vitro using DBA/2 mice. The splenocytes from male DBA/2 mice were cultured with BWMP in the presence of SCG, and the responses were assessed by measuring cytokines. BWMP suppressed IFN-γ and GM-CSF production by SCG, but not TNF-α production. To analyze the specificity of the reaction, similar experiments were conducted with BWMP in the presence of bacterial lipopolysaccharide (LPS); however, none of the cytokines were inhibited. Cytokine production of splenocytes by SCG was suggested to be largely dependent on the binding of lymphocytes with dendritic cells. Functions of BWMP were also analyzed by mixed lymphocyte reaction, and IFN-γ production was suppressed. These findings suggested that BWMP modulated the cell-to-cell contact induced by SCG and inhibited cytokine production. It is strongly suggested that the plant extracts modulate the immunostimulating effects of medicinal mushrooms. Cooperative effects of plants and mushrooms would be an important issue for functional foods.

Effect of Rubber Polarity on Cluster Formation in Rubbers Cross-Linked with Diels–Alder Chemistry

PubMed Central

2017-01-01

Diels–Alder chemistry has been used for the thermoreversible cross-linking of furan-functionalized ethylene/propylene (EPM) and ethylene/vinyl acetate (EVM) rubbers. Both furan-functionalized elastomers were successfully cross-linked with bismaleimide to yield products with a similar cross-link density. NMR relaxometry and SAXS measurements both show that the apolar EPM-g-furan precursor contains phase-separated polar clusters and that cross-linking with polar bismaleimide occurs in these clusters. The heterogeneously cross-linked network of EPM-g-furan contrasts with the homogeneous network in the polar EVM-g-furan. The heterogeneous character of the cross-links in EPM-g-furan results in a relatively high Young’s modulus, whereas the more uniform cross-linking in EVM-g-furan results in a higher tensile strength and elongation at break. PMID:29213149

P-chiral 1-phosphanorbornenes: from asymmetric phospha-Diels-Alder reactions towards ligand design and functionalisation.

PubMed

Möller, Tobias; Wonneberger, Peter; Sárosi, Menyhárt B; Coburger, Peter; Hey-Hawkins, Evamarie

2016-02-07

The principle of stereotopic face differentiation was successfully applied to 2H-phospholes which undergo a very efficient and highly stereoselective Diels-Alder reaction giving phosphorus-chiral 1-phosphanorbornenes with up to 87% yield. The observed reaction pathway has been supported by theoretical calculations showing that the cycloaddition reaction between 2H-phosphole 3a and the dienophile (5R)-(-)-menthyloxy-2(5H)-furanone (8) is of normal electron demand. Optically pure phosphanes were obtained by separation of the single diastereomers and subsequent desulfurisation of the sulfur-protected phosphorus atom. Finally, divergent ligand synthesis is feasible by reduction of the chiral auxiliary, subsequent stereospecific intramolecular Michael addition, and various functionalisations of the obtained key compound 13a. Furthermore, the unique structural properties of phospanorbornenes are presented and compared to those of phosphanorbornanes.

Microwave-promoted catalyst- and solvent-free aza-Diels-Alder reaction of aldimines with 6-[2-(dimethylamino)vinyl]-1,3-dimethyluracil.

PubMed

Sarma, Rupam; Sarmah, Manas M; Prajapati, Dipak

2012-02-17

A microwave-promoted aza-Diels-Alder reaction between 6-[2-(dimethylamino)vinyl]-1,3-dimethyluracil and aldimines has been developed for the construction of dihydropyrido[4,3-d]pyrimidines. Urea is effectively employed as an environmentally benign source of ammonia in the absence of any catalyst or solvent. The key step in the reaction is in situ generation and trapping of the reactive aldimine formed from urea and aldehyde by the diene system of the uracil. The reaction is clean, and excellent yields are obtained in a matter of a few minutes.

Diversity of Riparian Plants among and within Species Shapes River Communities

PubMed Central

Jackrel, Sara L.; Wootton, J. Timothy

2015-01-01

Organismal diversity among and within species may affect ecosystem function with effects transmitting across ecosystem boundaries. Whether recipient communities adjust their composition, in turn, to maximize their function in response to changes in donor composition at these two scales of diversity is unknown. We use small stream communities that rely on riparian subsidies as a model system. We used leaf pack experiments to ask how variation in plants growing beside streams in the Olympic Peninsula of Washington State, USA affects stream communities via leaf subsidies. Leaves from red alder (Alnus rubra), vine maple (Acer cinereus), bigleaf maple (Acer macrophyllum) and western hemlock (Tsuga heterophylla) were assembled in leaf packs to contrast low versus high diversity, and deployed in streams to compare local versus non-local leaf sources at the among and within species scales. Leaves from individuals within species decomposed at varying rates; most notably thin leaves decomposed rapidly. Among deciduous species, vine maple decomposed most rapidly, harbored the least algal abundance, and supported the greatest diversity of aquatic invertebrates, while bigleaf maple was at the opposite extreme for these three metrics. Recipient communities decomposed leaves from local species rapidly: leaves from early successional plants decomposed rapidly in stream reaches surrounded by early successional forest and leaves from later successional plants decomposed rapidly adjacent to later successional forest. The species diversity of leaves inconsistently affected decomposition, algal abundance and invertebrate metrics. Intraspecific diversity of leaf packs also did not affect decomposition or invertebrate diversity. However, locally sourced alder leaves decomposed more rapidly and harbored greater levels of algae than leaves sourced from conspecifics growing in other areas on the Olympic Peninsula, but did not harbor greater aquatic invertebrate diversity. In contrast to

Diversity of Riparian Plants among and within Species Shapes River Communities.

PubMed

Jackrel, Sara L; Wootton, J Timothy

2015-01-01

Organismal diversity among and within species may affect ecosystem function with effects transmitting across ecosystem boundaries. Whether recipient communities adjust their composition, in turn, to maximize their function in response to changes in donor composition at these two scales of diversity is unknown. We use small stream communities that rely on riparian subsidies as a model system. We used leaf pack experiments to ask how variation in plants growing beside streams in the Olympic Peninsula of Washington State, USA affects stream communities via leaf subsidies. Leaves from red alder (Alnus rubra), vine maple (Acer cinereus), bigleaf maple (Acer macrophyllum) and western hemlock (Tsuga heterophylla) were assembled in leaf packs to contrast low versus high diversity, and deployed in streams to compare local versus non-local leaf sources at the among and within species scales. Leaves from individuals within species decomposed at varying rates; most notably thin leaves decomposed rapidly. Among deciduous species, vine maple decomposed most rapidly, harbored the least algal abundance, and supported the greatest diversity of aquatic invertebrates, while bigleaf maple was at the opposite extreme for these three metrics. Recipient communities decomposed leaves from local species rapidly: leaves from early successional plants decomposed rapidly in stream reaches surrounded by early successional forest and leaves from later successional plants decomposed rapidly adjacent to later successional forest. The species diversity of leaves inconsistently affected decomposition, algal abundance and invertebrate metrics. Intraspecific diversity of leaf packs also did not affect decomposition or invertebrate diversity. However, locally sourced alder leaves decomposed more rapidly and harbored greater levels of algae than leaves sourced from conspecifics growing in other areas on the Olympic Peninsula, but did not harbor greater aquatic invertebrate diversity. In contrast to

Solvent effects in acid-catalyzed dehydration of the Diels-Alder cycloadduct between 2,5-dimethylfuran and maleic anhydride

NASA Astrophysics Data System (ADS)

Salavati-fard, Taha; Caratzoulas, Stavros; Doren, Douglas J.

2017-03-01

Dehydration of the cycloadduct produced from the Diels-Alder reaction between 2,5-dimethylfuran and maleic anhydride to 3,6-dimethylphthalic anhydride exemplifies an important step in producing platform chemicals from biomass. The mechanisms of dehydration and catalytic effects of Lewis and Brønsted acids are investigated with density functional theory. The uncatalyzed reaction has a very high activation barrier (68.7 kcal/mol) in the gas phase and it is not significantly affected by solvation. With a Lewis acid catalyst, modeled as an alkali ion, the activation barriers are reduced, but intermediates are also stabilized. The net effect in vacuum is that the energetic span, or apparent activation energy of the catalytic cycle, is 77.9 kcal/mol, even higher than the barrier in the uncatalyzed case. In solution, however, the energetic span is reduced by as much as 20 kcal/mol, due to differences in the solvation energy of the transition states and intermediates. In the case of a Brønsted acid catalyst, modeled as a proton, the gas phase transition state energies are reduced even more than in the Lewis acid case, and there is no strong stabilization of the intermediates. The energetic span in vacuum is only 13.8 kcal/mol and is reduced even further in solution. Brønsted acid catalysis appears to be the preferred mechanism for dehydration of this cycloadduct. Since the Diels-Alder reaction that produced the molecule has previously been shown to be catalyzed by Brønsted acids, this suggests that a single catalyst could be used to accelerate both steps.

Influence of primitive Biłgoraj horses on the glossy buckthorn (Frangula alnus)-dominated understory in a mixed coniferous forest

NASA Astrophysics Data System (ADS)

Klich, Daniel

2018-02-01

Changes in the understory dominated by glossy buckthorn Frangula alnus via the influence of primitive horses were analyzed in a 28-year-old enclosure in the village of Szklarnia at the Biłgoraj Horse-Breeding Centre near Janów Lubelski (eastern Poland). The analysis was conducted in 20 circular plots (30 m2) defined in adjacent, similar forest stands (enclosed and control). Disturbance by the horses, mainly through trampling, caused numerous paths to form within the glossy buckthorn-dominated understory and led to a decrease in density of stems of lower height classes (30-80 and 81-130 cm, respectively). An increase in species diversity at the expense of glossy buckthorn density was also observed. The horses' trampling caused an increase in Padus avium density and the encroachment of other woody plant species that were less shade-tolerant and grew well in soils rich in nutrients. An increase in the density of woody plants over 180 cm above ground was observed within the enclosure, which was probably the result of the horses' excretion of feces. The results presented here provide new insight into the ecological role that horses play in forest-meadow landscape mosaics, which, via altering the development of vegetation, may contribute to an increase in biodiversity within forest habitats.

Wood anatomical analysis of Alnus incana and Betula pendula injured by a debris-flow event.

PubMed

Arbellay, Estelle; Stoffel, Markus; Bollschweiler, Michelle

2010-10-01

Vessel chronologies in ring-porous species have been successfully employed in the past to extract the climate signal from tree rings. Environmental signals recorded in vessels of ring-porous species have also been used in previous studies to reconstruct discrete events of drought, flooding and insect defoliation. However, very little is known about the ability of diffuse-porous species to record environmental signals in their xylem cells. Moreover, time series of wood anatomical features have only rarely been used to reconstruct former geomorphic events. This study was therefore undertaken to characterize the wood anatomical response of diffuse-porous Alnus incana (L.) Moench and Betula pendula Roth to debris-flow-induced wounding. Tree microscopic response to wounding was assessed through the analysis of wood anatomical differences between injured rings formed in the debris-flow event year and uninjured rings formed in the previous year. The two ring types were examined close and opposite to the injury in order to determine whether wound effects on xylem cells decrease with increasing tangential distance from the injury. Image analysis was used to measure vessel parameters as well as fiber and parenchyma cell (FPC) parameters. The results of this study indicate that injured rings are characterized by smaller vessels as compared with uninjured rings. By contrast, FPC parameters were not found to significantly differ between injured and uninjured rings. Vessel and FPC parameters mainly remained constant with increasing tangential distance from the injury, except for a higher proportion of vessel lumen area opposite to the injury within A. incana. This study highlights the existence of anatomical tree-ring signatures-in the form of smaller vessels-related to past debris-flow activity and addresses a new methodological approach to date injuries inflicted on trees by geomorphic processes.

A Single Molecular Diels-Alder Crosslinker for Achieving Recyclable Cross-Linked Polymers.

PubMed

Chen, Shengli; Wang, Fenfen; Peng, Yongjin; Chen, Tiehong; Wu, Qiang; Sun, Pingchuan

2015-09-01

A triol-functional crosslinker combining the thermoreversible properties of Diels-Alder (DA) adducts in one molecule is designed, synthesized, and used as an ideal substitute of a traditional crosslinker to prepare thermal recyclable cross-linked polyurethanes with excellent mechanical properties and recyclability in a very simple and efficient way. The recycle property of these materials achieved by the DA/retro-DA reaction at a suitable temperature is verified by differential scanning calorimetry and in situ variable temperature solid-state NMR experiments during the cyclic heating and cooling processes. The thermal recyclability and remending ability of the bulk polyurethanes is demonstrated by three polymer processing methods, including hot-press molding, injection molding, and solution casting. It is notable that all the recycled cross-linked polymers display nearly invariable elongation/stress at break compared to the as-synthesized samples. Further end-group functionalization of this single molecular DA crosslinker provides the potential in preparing a wide range of recyclable cross-linked polymers. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reactions of hexadehydro-Diels-Alder benzynes with structurally complex multifunctional natural products

NASA Astrophysics Data System (ADS)

Ross, Sean P.; Hoye, Thomas R.

2017-06-01

An important question in organic chemistry concerns the extent to which benzynes—one of the classical reactive intermediates in organic chemistry—can react in discriminating fashion with trapping reagents. In particular, whether these species can react selectively with substrates containing multiple functional groups and possible sites of reactivity has remained unanswered. Natural products comprise a palette of multifunctional compounds with which to address this question. Here, we show that benzynes produced by the hexadehydro-Diels-Alder (HDDA) reaction react with many secondary metabolites with a preference for one among several pathways. Examples demonstrating such selectivity include reactions with: phenolics, through dearomatizing ortho-substitution; alkaloids, through Hofmann-type elimination; tropolone and furan, through cycloaddition; and alkaloids, through three-component fragmentation-coupling reactions. We also demonstrate that the cinchona alkaloids quinidine and quinine give rise to products (some in as few as three steps) that enable subsequent and rapid access to structurally diverse polyheterocyclic compounds. The results show that benzynes are quite discriminating in their reactivity—a trait perhaps not broadly enough appreciated.

Late Stage 5 Glacio-isostatic Sea in the St. Lawrence Valley, Canada and United States

USGS Publications Warehouse

Occhietti, S.; Balescu, S.; Lamothe, M.; Clet, M.; Cronin, T.; Ferland, P.; Pichet, P.

1996-01-01

Although post-glacial marine sediments of late Wisconsinan and early Holocene age are common in eastern Canada and the northeastern United States, remnants of older Pleistocene marine sediments are scarce. A fossiliferous marine clay that predates the classical Wisconsinan was recently discovered in the St. Lawrence Valley. A dominantly estuarine environment is inferred from the geochemistry of the shells (??18O = -7.1) and from benthic foraminifer and ostracode assemblages. The clay indicates a marine invasion (Cartier Sea) shallower and probably shorter than that during the upper late Wisconsinan Champlain Sea episode (12,000-9,500 yr B.P.). The pollen content shows that regional vegetation during the marine episode began as open tundra, then became a Betula and Alnus crispa forest, reached a climatic optimum with Quercus, Corylus, and Abies, and concluded as a Pinus/Picea boreal forest. A corrected infrared stimulated luminescence age of 98,000 ?? 9000 yr is compatible with the epimerization ratio of shells. The Cartier Sea resulted from a post-glacial glacio-isostatic marine invasion in the St. Lawrence lowlands. It probably occurred during late stage 5 and is tentatively assigned to the transition of oxygen isotope substages 5b/5a. This marine episode dates to stage 5 of the preceding continental glacier which extended to middle latitudes in NE America. ?? 1996 University of Washington.

Monitoring vegetation water uptake in a semiarid riparian corridor

NASA Astrophysics Data System (ADS)

Robinson, J.; Ochoa, C. G.; Leonard, J.

2015-12-01

With a changing global climate and growing demand for water throughout the world, responsible and sustainable land and water resource management practices are becoming increasingly important. Accounting for the amount of water used by riparian vegetation is a critical element for better managing water resources in arid and semiarid environments. The objective of this study was to determine water uptake by selected riparian vegetative species in a semiarid riparian corridor in North-Central Oregon. Exo-skin sap flow sensors (Dynamax, Houston, TX, U.S.A.) were used to measure sap flux in red alder (Alnus rubra) trees, the dominant overstory vegetation at the field site. Xylem sap flow data was collected from selected trees at the field site and in a greenhouse setting. Transpiration rates were determined based on an energy balance method, which makes it possible to estimate the mass flow of sap by measuring the velocity of electrical heat pulses through the plant stem. Preliminary field results indicate that red alder tree branches of about 1 inch diameter transpire between 2 and 6 kg of water/day. Higher transpiration rates of up to 7.3 kg of water/day were observed under greenhouse conditions. Streamflow and stream water temperature, vegetation characteristics, and meteorological data were analyzed in conjunction with transpiration data. Results of this study provide insight on riparian vegetation water consumption in water scarce ecosystems. This study is part of an overarching project focused on climate-vegetation interactions and ecohydrologic processes in arid and semiarid landscapes.

Classical Example of Total Kinetic and Thermodynamic Control: The Diels-Alder Reaction between DMAD and Bis-furyl Dienes.

PubMed

Borisova, Kseniya K; Kvyatkovskaya, Elizaveta A; Nikitina, Eugeniya V; Aysin, Rinat R; Novikov, Roman A; Zubkov, Fedor I

2018-04-20

A rare example of chemospecificity in the tandem Diels-Alder reaction of activated alkynes and bis-dienes has been revealed. The reaction between bis-furyl dienes and DMAD occurs at 25-80 °C and leads to kinetically controlled "pincer" adducts, 4a,8a-disubstituted 1,4:5,8-diepoxynaphthalenes. On the contrary, only thermodynamically controlled "domino" adducts (2,3-disubstituted 1,4:5,8-diepoxynaphthalenes) are formed in the same reaction at 140 °C. The "pincer" adducts can be transformed to the "domino" adducts at heating. The rate constants for reactions of both types were calculated using dynamic 1 H NMR spectroscopy.

Diels-Alder reactions of 12-hydroxy-9(10®20)-5aH-abeo-abieta-1(10),8(9),12(13)-triene-11,14-dione.

PubMed

Majetich, George; Zhang, Yong; Tian, Xinrong; Zou, Ge; Li, Yang; Wang, Yangyang; Hu, Shougang; Huddleston, Eric

2013-06-14

12-Hydroxy-9(10-->20)-5aH-abeo-abieta-1(10),8(9),12(13)-triene-11,14-dione (quinone 2) served as the dienophile in numerous intermolecular Diels-Alder reactions. These cycloadditions were conducted either thermally (including microwave heating) or with Lewis acid activation. While most dienes reacted with quinone 2 in good chemical yield, others were incompatible under the experimental conditions used.

Syntheses of the Stemona Alkaloids (±)-Stenine, (±)-Neostenine, and (±)-13-Epineostenine Using a Stereodivergent Diels-Alder/Azido-Schmidt Reaction

PubMed Central

Frankowski, Kevin J.; Golden, Jennifer E.; Zeng, Yibin; Lei, Yao; Aubé, Jeffrey

2009-01-01

A tandem Diels-Alder/azido Schmidt reaction sequence provides rapid access to the core skeleton shared by several Stemona alkaloids including stenine, neostenine, tuberstemonine, and neotubererostemonine. The discovery and evolution of inter- and intramolecular variations of this process and their applications to total syntheses of (±)–stenine and (±)–neostenine is described. The stereochemical outcome of the reaction depends on both substrate type and reaction condition, enabling the preparation of both (±)–stenine and (±)–neostenine from the same diene/dienophile combination. PMID:18396881

Increasing the biomass production of short rotation coppice forests. Progress report. [Sycamore, sweet gum, alder, and locust

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steinbeck, K.; Brown, C. L.

1979-03-01

Two biomass plantations, one in the Coastal Plain, the other in the Piedmont province of Georgia, have been established. Platanus occidentalis, Liquidambar styraciflua, Flnus glutinosa and Robinia pseudoacacia were planted in pure and mixed plots. Differences in the growth at the end of the first growing season were attributed mostly to weed competition in the Coastal Plain. Robinia grew remarkably well in the Piedmont, averaging more than 2.2 m tall in irrigated plots. A fungus tentatively identified as belonging to the genus Botryosphaeria is causing heavy Alnus mortality in the Coastal Plain. Progress in the genetic improvement phase of themore » project included a collection of Platanus seedlots from throughout Georgia to identify promising provenances and the production of Liquidambar and Robinia plantlets in tissue culture. Differences in the calorific content of young sprout material from nine hardwood species (unit oven dry weight basis) were found to be small. Other studies dealt with the effects of different harvesting cycles on the size and carbohydrate contents of sycamore rootstocks.« less

One-pot Diels–Alder cycloaddition/gold(I)-catalyzed 6-endo-dig cyclization for the synthesis of the complex bicyclo[3.3.1]alkenone framework

PubMed Central

Sow, Boubacar; Bellavance, Gabriel; Barabé, Francis

2011-01-01

Summary The rapid synthesis of bicyclo[m.n.1]alkanone cores possessing quaternary carbon centers adjacent to a bridged ketone represents a significant synthetic challenge. This type of architectural feature is embedded in various complex biologically active compounds such as hyperforin and garsubellin A. Herein, we report a highly diastereoselective one-pot Diels–Alder reaction/Au(I)-catalyzed carbocyclization to generate bicyclo[3.3.1]alkanones in yields ranging from 48–93%. PMID:21915201

Heteropoly acid-catalyzed microwave-assisted three-component aza-Diels-Alder cyclizations: diastereoselective synthesis of potential drug candidates for Alzheimer's disease.

PubMed

Borkin, Dmitry; Morzhina, Elena; Datta, Silpi; Rudnitskaya, Aleksandra; Sood, Abha; Török, Marianna; Török, Béla

2011-03-07

A highly diastereoselective microwave-assisted three component synthesis of azabicyclo[2.2.2]octan-5-ones by a silicotungstic acid-catalyzed aza-Diels-Alder cyclization is described. The one-pot process involves the formation of the in situ generated Schiff base and its immediate cyclization with cyclohex-2-enone. The short reaction times, good yields and excellent diastereoselectivity make this annulation a practical and environmentally attractive method for the synthesis of the target compounds. Preliminary assays were carried out to determine the activity of the products in AChE as well as in amyloid β fibrillogenesis inhibition.

Cross-Diels-Alder reactions of 6-oxo-1-sulfonyl-1,6-dihydropyridine-3-carboxylates.

PubMed

Teyssot, Marie-Laure; Lormier, Anh-Tuan; Chataigner, Isabelle; Piettre, Serge R

2007-03-30

Electron-poor 6-oxo-1-sulfonyl-1,6-dihydropyridine-3-carboxylates 1b-d undergo cross-Diels-Alder reactions with electron-rich dienes 4a-f under hyperbaric conditions, reacting either as dienophiles to yield normal-electron-demand (NED) cycloadducts 10 and/or 11 or as dienes to give inverse-electron-demand (IED) cycloadducts 12 and/or 13. The latter are converted into 14 and/or 15 through an NED cycloaddition with a second equivalent of electron-rich diene. Acyclic dienes display a propensity to yield NED products, whereas cyclic dienes tend to favor IED cycloadducts. High-pressure activation compares favorably with thermal or microwave activation in terms of both yields and suppression of the transformation of 1 into unreactive pyridines 3. Whereas the Cope rearrangement from IED to NED occurs under thermal conditions, no evidence of its involvement under high pressure could be detected. These and other data point to similar activation energies for the NED and IED processes under these conditions.

The dynamics of the Corylus, Alnus, and Betula pollen seasons in the context of climate change (SW Poland).

PubMed

Malkiewicz, Małgorzata; Drzeniecka-Osiadacz, Anetta; Krynicka, Justyna

2016-12-15

The changes in the main features of early spring tree or shrub pollen seasons are important due to the significant impact on the occurrence of pollen-related allergy symptoms. This study shows the results of pollen monitoring for a period of eleven years (2003-2013) using a Burkard volumetric spore trap. The main characteristics of the hazel, alder, and birch pollination season were studied in Wrocław (SW Poland). The statistical analyses do not show a significant trend of annual total pollen count or shift in timing of the pollen season in the period of analysis. The research confirms a great impact (at the statistically significant level of 0.05) of the heat resources on pollination season (the value of the correlation coefficient ranges from -0.63 up to -0.87). Meteorological variables (e.g. sum of temperature for selected period) were compiled to 5-year running means to examine trends. Changes in the pollination period features due to climate change including both timing and intensity of pollen productivity, would have important consequences for allergy sufferers. Copyright © 2016 Elsevier B.V. All rights reserved.

Daldinia decipiens and Entonaema cinnabarina as fungal symbionts of Xiphydria wood wasps.

PubMed

Srůtka, Petr; Pazoutová, Sylvie; Kolarík, Miroslav

2007-02-01

The identity of symbiotic fungi associated with the Xiphydria spp. wood wasps was investigated using DNA analysis. The fungi were isolated from the mycangia of adult females of X. camelus, X. prolongata and X. longicollis reared from colonized logs of Alnus glutinosa, Salix alba and Quercus robur, respectively. Sequences of rDNA and beta-tubulin were obtained. Phylogenetic analysis based on the NJ method showed that the isolates from X. camelus clustered with Daldinia decipiens, whereas those of X. prolongata belonged to Entonaema cinnabarina. In X. longicollis, both symbiotic fungi (D. decipiens and E. cinnabarina) have been found. Morphological characteristics of the anamorphs are presented. In cultures of D. decipiens, sympodial holoblastic, as well as annelidic, conidiation was observed. So far, fruit bodies of D. decipiens have only been recorded from Betula spp. whereas the host spectrum of its wasp vectors covers predominantly oaks and alders. Fruiting bodies of E. cinnabarina do not occur in Central Europe. This is the first report of Entonaema as a symbiotic fungus of siricid wood wasps.

Three-Dimensional Graphene Structure for Healable Flexible Electronics Based on Diels-Alder Chemistry.

PubMed

Li, Jinhui; Liu, Qiang; Ho, Derek; Zhao, Songfang; Wu, Shuwen; Ling, Lei; Han, Fei; Wu, Xinxiu; Zhang, Guoping; Sun, Rong; Wong, Ching-Ping

2018-03-21

Wearable electronics with excellent stretchability and sensitivity have emerged as a very promising field with wide applications such as e-skin and human motion detection. Although three-dimensional (3D) graphene structures (GS) have been reported for high-performance strain sensors, challenges still remain such as the high cost of GS preparation, low stretchability, and the lack of ability to heal itself. In this paper, we reported a novel self-healing flexible electronics with 3D GS based on Diels-Alder (DA) chemistry. Furfurylamine (FA) was employed as a reducing as well as a modifying agent, forming GS by FA (FAGS)/DA bonds contained polyurethane with the "infiltrate-gel-dry" process. The as-prepared composite exhibited excellent stretchability (200%) and intrinsic conductivity with low incorporation of graphene (about 2 wt %), which could be directly employed for flexible electronics to detect human motions. Besides, the FAGS/DAPU composite exhibited lower temperature retro-DA response for the continuous graphene networks. Highly effective healing of the composites by heat and microwave has been demonstrated successfully.

A diels-alder modulated approach to control and sustain the release of dexamethasone and induce osteogenic differentiation of human mesenchymal stem cells

PubMed Central

Koehler, Kenneth C.; Alge, Daniel L.; Anseth, Kristi S.; Bowman, Christopher N.

2013-01-01

We report a new approach to controlled drug release based upon exploiting the dynamic equilibrium that exists between Diels-Alder reactants and products, demonstrating the release of a furan containing dexamethasone peptide (dex-KGPQG-furan) from a maleimide containing hydrogel. Using a reaction-diffusion model, the release kinetics were tuned to achieve sustained concentrations conducive to osteogenic differentiation of human mesenchymal stem cells (hMSCs). Efficacy was first demonstrated in a 2D culture model, in which dexamethasone release induced significant increases in alkaline phosphatase (ALP) activity and mineral deposition in hMSCs compared to a dexamethasone-free treatment. The results were similar to that observed with a soluble dexamethasone treatment. More dramatic differences were observed in 3D culture, where co-encapsulation of a dexamethasone releasing hydrogel depot within an hMSC-laden extracellular matrix mimetic poly(ethylene glycol) hydrogel resulted in a local and robust osteogenic differentiation. ALP activity reached levels that were up to six times higher than the dexamethasone free treatment. Interestingly, at 5 and 10 day time points, the ALP activity exceeded the dexamethasone positive control, suggesting a potential benefit of sustained release in 3D culture. After 21 days, substantial mineralization comparable to the positive control was also observed in the hydrogels. Collectively, these results demonstrate Diels-Alder modulated release as an effective and versatile new platform for controlled drug delivery that may prove especially beneficial for sustaining the release of low molecular weight molecules in hydrogel systems. PMID:23465826

Transatlantic invasion routes and adaptive potential in North American populations of the invasive glossy buckthorn, Frangula alnus

PubMed Central

De Kort, Hanne; Mergeay, Joachim; Jacquemyn, Hans; Honnay, Olivier

2016-01-01

Background and Aims Many invasive species severely threaten native biodiversity and ecosystem functioning. One of the most prominent questions in invasion genetics is how invasive populations can overcome genetic founder effects to establish stable populations after colonization of new habitats. High native genetic diversity and multiple introductions are expected to increase genetic diversity and adaptive potential in the invasive range. Our aim was to identify the European source populations of Frangula alnus (glossy buckthorn), an ornamental and highly invasive woody species that was deliberately introduced into North America at the end of the 18th century. A second aim of this study was to assess the adaptive potential as an explanation for the invasion success of this species. Methods Using a set of annotated single-nucleotide polymorphisms (SNPs) that were assigned a putative function based on sequence comparison with model species, a total of 38 native European and 21 invasive North American populations were subjected to distance-based structure and assignment analyses combined with population genomic tools. Genetic diversity at SNPs with ecologically relevant functions was considered as a proxy for adaptive potential. Key Results Patterns of invasion coincided with early modern transatlantic trading routes. Multiple introductions through transatlantic trade from a limited number of European port regions to American urban areas led to the establishment of bridgehead populations with high allelic richness and expected heterozygosity, allowing continuous secondary migration to natural areas. Conclusions Targeted eradication of the urban populations, where the highest genetic diversity and adaptive potential were observed, offers a promising strategy to arrest further invasion of native American prairies and forests. PMID:27539599

ent-Kaurane-Based Regio- and Stereoselective Inverse Electron Demand Hetero-Diels-Alder Reactions: Synthesis of Dihydropyran-Fused Diterpenoids†

PubMed Central

Ding, Chunyong; Wang, Lili; Chen, Haijun; Wild, Christopher; Ye, Na; Ding, Ye; Wang, Tianzhi; White, Mark A.; Shen, Qiang; Zhou, Jia

2014-01-01

A mild and concise approach for the construction of 3,4-dihydro-2H-pyran ring integrated into the A-ring of the natural product oridonin using an optimized inverse electron demand hetero-Diels-Alder (IED HDA) reaction is reported herein. A self-dimerization of the exocyclic enone installed in the A-ring through a homo-HDA reaction was identified to exclusively give a dimeric ent-kaurane diterpenoid with the spirochroman core. Moreover, the efficient cross-HDA cycloadditions of this enone with various vinyl ethers or vinyl sulfides, instead of its own homo-HDA dimerization, were achieved in regio- and stereoselective manners, thus providing the access to novel dihydropyran-fused diterpenoids as potential anticancer agents to overcome chemoresistance. PMID:25225052

Intramolecular Aza-Diels-Alder Reactions of ortho-Quinone Methide Imines: Rapid, Catalytic, and Enantioselective Assembly of Benzannulated Quinolizidines.

PubMed

Kretzschmar, Martin; Hofmann, Fabian; Moock, Daniel; Schneider, Christoph

2018-04-16

Aza-Diels-Alder reactions (ADARs) are powerful processes that furnish N-heterocycles in a straightforward fashion. Intramolecular variants offer the additional possibility of generating bi- and polycyclic systems with high stereoselectivity. We report herein a novel Brønsted acid catalyzed process in which ortho-quinone methide imines tethered to the dienophile via the N substituent react in an intramolecular ADAR to form complex quinolizidines and oxazinoquinolines in a one-step process. The reactions proceed under very mild conditions, with very good yields and good to very good diastereo- and enantioselectivities. Furthermore, the process was extended to a domino reaction that efficiently combines substrate synthesis, ortho-quinone methide imine formation, and ADAR. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Irreversible endo-selective diels-alder reactions of substituted alkoxyfurans: a general synthesis of endo-cantharimides.

PubMed

Foster, Robert W; Benhamou, Laure; Porter, Michael J; Bučar, Dejan-Krešimir; Hailes, Helen C; Tame, Christopher J; Sheppard, Tom D

2015-04-13

The [4+2] cycloaddition of 3-alkoxyfurans with N-substituted maleimides provides the first general route for preparing endo-cantharimides. Unlike the corresponding reaction with 3H furans, the reaction can tolerate a broad range of 2-substitued furans including alkyl, aromatic, and heteroaromatic groups. The cycloaddition products were converted into a range of cantharimide products with promising lead-like properties for medicinal chemistry programs. Furthermore, the electron-rich furans are shown to react with a variety of alternative dienophiles to generate 7-oxabicyclo[2.2.1]heptane derivatives under mild conditions. DFT calculations have been performed to rationalize the activation effect of the 3-alkoxy group on a furan Diels-Alder reaction. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Effects of a natural dam-break flood on geomorphology and vegetation on the Elwha River, Washington, U.S.A.

USGS Publications Warehouse

Acker, S.A.; Beechie, T.J.; Shafroth, P.B.

2008-01-01

Ephemeral dams caused by landslides have been observed around the world, yet little is known about the effects of their failure on landforms and vegetation. In 1967, a landslide-dam-break flood in a pristine reach of the Elwha River valley filled the former channel and diverted the river. The reach is a reference site for restoration following the planned removal of dams on the river. We identified five surfaces on the 25 ha debris fan deposited by the flood. Based on tree ages and historic air photos, three of the surfaces formed in 1967, while two formed later. The surfaces varied in substrate (silt and sand, to boulders), and height above the river channel. Tree mortality resulted from tree removal and burial by sediment, the latter leaving snags and some surviving trees. Tree species composition was generally consistent within each surface. Dominant species included red alder (Alnus rubra) and Sitka willow (Salix sitchensis), alone or in combination, a combination of Douglas-fir (Pseudotsuga menziesii) and black cottonwood (Populus balsamifera ssp. trichocarpa), or a combination of alder and Cottonwood. There were significant differences between surfaces in stem density, basal area, and rate of basal area growth. The large degree of heterogeneity in forest structure, composition, and productivity within a relatively small floodplain feature is in part due to spatial variability in the intensity of a single disturbance event, and in part due to the occurrence of subsequent, smaller events. To recreate natural diversity of riparian forests may require mimicking the variety of physical and biotic habitats that a single, complex disturbance event may create.

Holocene environmental changes in southern Kamchatka, Far Eastern Russia, inferred from a pollen and testate amoebae peat succession record

NASA Astrophysics Data System (ADS)

Klimaschewski, A.; Barnekow, L.; Bennett, K. D.; Andreev, A. A.; Andrén, E.; Bobrov, A. A.; Hammarlund, D.

2015-11-01

High resolution palaeoenvironmental records in Far-Eastern Russia are rare, and the Kamchatka Peninsula is among the least studied areas of the region. This paper describes a record spanning the last ca. 11,000 yr, obtained from a bog in the southern part of Kamchatka. The radiocarbon dated core was analysed for pollen, testate amoebae, charcoal and loss-on-ignition (LOI). The vegetation during the early Holocene was dominated by grasses (Poaceae), birch (Betula) and heath (Ericaceae p. p.). Around 10,300 cal yr BP there was a substantial change in the vegetation cover to shrub alder (Alnus viridis s.l.) stands with sedges and ferns (Polypodiophyta) as well as herbs such as meadow rue (Thalictrum) in the understory. In the surroundings of Utka peatlands started to form. The variations in the vegetation cover were most probably caused by climatic changes. At the beginning of sediment accumulation, before 10,300 cal yr BP, the composition of the vegetation points to cooler summers and/or decreased annual precipitation. Around 10,300 cal yr BP, changes in vegetation occurred due to rising temperatures and/or changed water regimes. Increased abundancies of dry indicating testate amoebae after 9100 cal yr BP point to intermediate to dry soil conditions. Between 8600 and 7700 cal yr BP tree alder (Alnus incana) was widely spread at the site which probably indicates optimal environmental conditions. The tephra layer at 381-384.5 cm (ca. 8500 cal yr BP) produces a strong impact on the testate amoebae assemblages. At 7700 cal yr BP there was a sudden drop of A. incana in the local vegetation. From this time on, A. incana and also A. viridis decrease continuously whereas Betula gradually increases. The upper part of the sequence (after 6300 cal yr BP) shows higher abundancies of meadowsweet (Filipendula) and sweet gale (Myrica) pollen. After 6300 cal yr BP, changes in testate amoebae demonstrate variable soil moisture conditions at the site. Between 3700 and 1800 cal yr BP

Random quaternary ammonium Diels-Alder poly(phenylene) copolymers for improved vanadium redox flow batteries

NASA Astrophysics Data System (ADS)

Largier, Timothy D.; Cornelius, Chris J.

2017-06-01

This study analyzes the effect of quaternary ammonium homopolymer (AmPP) and ionic and non-ionic random unit copolymerization (AmPP-PP) of Diels-Alder poly(phenylene)s on electrochemical and transport properties, vanadium redox flow battery performance, and material stability. AmPP-PP materials were synthesized with IEC's up to 2.2 meq/g, displaying a carbonate form ion conductivity of 17.3 mS/cm and water uptake of 57.3%. Vanadium ion permeability studies revealed that the random copolymers possess superior charge carrier selectivity. For materials of comparable ion content, at 10 mA/cm2 the random copolymer displayed a 14% increase in coulombic efficiency (CE) corresponding to a 7% increase in energy efficiency. All quaternary ammonium materials displayed ex situ degradation in a 0.5 M V5+ + 5 M H2SO4 solution, with the rate of degradation appearing to increase with IEC. Preliminary studies reveal that the neutralizing counter-ion has a significant effect on VRB performance, proportional to changes in vanadium ion molecular diffusion.

An MM and QM Study of Biomimetic Catalysis of Diels-Alder Reactions Using Cyclodextrins

PubMed Central

Chen, Wei; Sun, Lipeng; Tang, Zhiye; Ali, Zulfikhar A.; Wong, Bryan M.; Chang, Chia-en A.

2018-01-01

We performed a computational investigation of the mechanism by which cyclodextrins (CDs) catalyze Diels-Alder reactions between 9-anthracenemethanol and N-cyclohexylmaleimide. Hydrogen bonds (Hbonds) between N-cyclohexylmaleimide and the hydroxyl groups of cyclodextrins were suggested to play an important role in this catalytic process. However, our free energy calculations and molecular dynamics simulations showed that these Hbonds are not stable, and quantum mechanical calculations suggested that the reaction is not promoted by these Hbonds. The binding of 9-anthracenemethanol and N-cyclohexylmaleimide to cyclodextrins was the key to the catalytic process. Cyclodextrins act as a container to hold the two reactants in the cavity, pre-organize them for the reactions, and thus reduce the entropy penalty to the activation free energy. Dimethyl-β-CD was a better catalyst for this specific reaction than β-CD because of its stronger van der Waals interaction with the pre-organized reactants and its better performance in reducing the activation energy. This computational work sheds light on the mechanism of the catalytic reaction by cyclodextrins and introduces new perspectives of supramolecular catalysis. PMID:29938117

Synthesis of Polyheterocyclic Pyrrolo[3,4-b]pyridin-5-ones via a One-Pot (Ugi-3CR/aza Diels-Alder/N-acylation/aromatization/SN2) Process. A Suitable Alternative towards Novel Aza-Analogues of Falipamil.

PubMed

Zamudio-Medina, Angel; García-González, Ailyn N; Herrera-Carrillo, Genesis K; Zárate-Zárate, Daniel; Benavides-Macías, Adriana; Tamariz, Joaquín; Ibarra, Ilich A; Islas-Jácome, Alejandro; González-Zamora, Eduardo

2018-03-27

We describe the one-pot synthesis of twenty polyheterocyclic pyrrolo[3,4- b ]pyridin-5-ones via a cascade process (Ugi-3CR/aza Diels-Alder/ N -acylation/aromatization) in 20 to 95% overall yields, as well as four pharmacologically promising analogues via an improved cascade process (Ugi-3CR/aza Diels-Alder/ N -acylation/aromatization/S N 2): two piperazine-linked pyrrolo[3,4- b ]pyridin-5-ones in 33 and 34%, and a couple of Falipamil aza-analogues in 30 and 35% overall yields. It is worth highlighting the good substrate scope found, because final products are furnished with alkyl, aryl, and heterocyclic substituents. The use of chain-ring tautomerizable isocyanides (as key reagents for the Ugi-type three component reaction) allowed for a rapid and efficient assembly of the polysubstituted oxindoles, which were used in situ toward the complex products, conferring features like robustness, sustainability, and the one-pot approach to this synthetic methodology.

Novel Diels-Alder based self-healing epoxies for aerospace composites

NASA Astrophysics Data System (ADS)

Coope, T. S.; Turkenburg, D. H.; Fischer, H. R.; Luterbacher, R.; van Bracht, H.; Bond, I. P.

2016-08-01

Epoxy resins containing Diels-Alder (DA) furan and maleimide moieties are presented with the capability to self-heal after exposure to an external heat source. A conventional epoxy amine system has been combined with furfuryl and maleimide functional groups in a two-step process, to avoid major side-reactions, and the concentration of a thermo-reversibly binding cross-linker was considered to balance thermoset and thermoplastic behaviours, and the subsequent self-healing performance. In the context of self-repair technologies an inbuilt ‘intrinsic’ self-healing system is deemed favourable as the healing agent can be placed in known ‘hot spot’ regions (i.e. skin-stringer run outs, ply drops and around drilled holes) where operational damage predominately occurs in load bearing aerospace structures. In this study, the mechanical and self-healing performance of furan functionalised epoxy resins containing varying amounts (10, 20, 30 or 40 pph) of bismaleimide were investigated using a bulk epoxy polymer tapered double cantilever beam test specimen geometry. Two forms, a thin film and a bulk material, were evaluated to account for future integration methods into fibre reinforced polymer (FRP) composites. The highest healing efficiency, with respect to the obtained initial load value, was observed from the 20 pph bulk material derivative. The polymers were successful in achieving consistent multiple (three) healing cycles when heated at 150 °C for 5 min. This novel investigated DA material exhibits favourable processing characteristics for FRP composites as preliminary studies have shown successful coextrution with reinforcing fibres to form free standing films and dry fibre impregnation.

Postglacial vegetation history of the Kachemak Bay area, Cook Inlet, south-central Alaska: A section in Geologic studies in Alaska by the U.S. Geological Survey, 1998

USGS Publications Warehouse

Ager, Thomas A.

2000-01-01

Pollen records from two sites on the north shore of Kachemak Bay, south-central Alaska, provide the first radiocarbon-dated histories of postglacial vegetation development for southern Cook Inlet. During the late Wisconsin glacial interval, glaciers covered most of Cook Inlet. Deglaciation of Kachemak Bay began prior to 13,000 yr B.P. Pollen evidence indicates that a pioneering herbaceous tundra began to develop by 12,800 yr B.P., but was soon replaced by a shrub tundra of dwarf birch (Betula), Ericales (Ericaceae and Empetrum) and willows (Salix).By 9,500 yr B.P., a shrub-dominated vegetation of alders (Alnus) and willows, with some deciduous trees (Populus spp.) quickly developed and persisted until late Holocene time. By about 4,000–3,800 yr B.P., spruce trees (Picea glauca and (or) P. mariana) from the interior boreal forests reached the northern Kachemak Bay area from upper Cook Inlet and began to displace the alder-dominated vegetation. A coastal forest of Sitka spruce (Picea sitchensis) began to colonize Kachemak Bay more recently, about 1,650 yr B.P. (minimum age), apparently from sources in Prince William Sound to the east. Where Sitka spruce came into proximity with boreal white spruce (Picea glauca), hybridization occurred, ultimately influencing the spruce forests over a large area of the Kenai Lowland. Some key findings of this study are: (1) the Kachemak Bay-area pollen records do not display persuasive evidence for a “Younger Dryas” cold, dry interval ca. 11,000–10,000 yr B.P. that has been reported from pollen records on Kodiak Island (Gulf of Alaska) and Pleasant Island (southeastern Alaska); (2) at least one species of alder may have survived in refugia in south-central Alaska during the last glacial interval; (3) coastal forests appear to be still migrating west along the coast of south-central Alaska, but their spread northward is being limited by drier, colder winter climates; (4) the mountainous topography of south-central Alaska

Soil aggregation and slope stability related to soil density, root length, and mycorrhiza

NASA Astrophysics Data System (ADS)

Graf, Frank; Frei, Martin

2013-04-01

Eco-engineering measures combine the use of living plants and inert mechanical constructions to protect slopes against erosion and shallow mass movement. Whereas in geotechnical engineering several performance standards and guidelines for structural safety and serviceability of construction exist, there is a lack of comparable tools in the field of ecological restoration. Various indicators have been proposed, including the fractal dimension of soil particle size distribution, microbiological parameters, and soil aggregate stability. We present results of an soil aggregate stability investigation and compare them with literature data of the angle of internal friction ?' which is conventionally used in slope stability analysis and soil failure calculation. Aggregate stability tests were performed with samples of differently treated moraine, including soil at low (~15.5 kN/m³) and high (~19.0 kN/m³) dry unit weight, soil planted with Alnus incana (White Alder) as well as the combination of soil planted with alder and inoculated with the mycorrhizal fungus Melanogaster variegatus s.l. After a 20 weeks growth period in a greenhouse, a total of 100 samples was tested and evaluated. Positive correlations were found between the soil aggregate stability and the three variables dry unit weight, root length per soil volume, and degree of mycorrhization. Based on robust statistics it turned out that dry unit weight and mycorrhization degree were strongest correlated with soil aggregate stability. Compared to the non-inoculated control plants, mycorrhized White Alder produced significantly more roots and higher soil aggregate stability. Furthermore, the combined biological effect of plant roots and mycorrhizal mycelia on aggregate stability on soil with low density (~15.5 kN/m³) was comparable to the compaction effect of the pure soil from 15.5 to ~19.0 kN/m³. Literature data on the effect of vegetation on the angle of internal friction ?' of the same moraine showed

Diels Alder polyphenylene anion exchange membrane for nonaqueous redox flow batteries

DOE PAGES

Small, Leo J.; Pratt, III, Harry D.; Fujimoto, Cy H.; ...

2015-10-23

Here highly conductive, solvent-resistant anionic Diels Alder polyphenylene (DAPP) membranes were synthesized with three different ionic contents and tested in an ionic liquid-based nonaqueous redox flow battery (RFB). These membranes display 3–10× increase in conductivity in propylene carbonate compared to some commercially available (aqueous) anion exchange membranes. The membrane with an ion content of 1.5 meq/g (DAPP1.5) proved too brittle for operation in a RFB, while the membrane with an ion content of 2.5 meq/g (DAPP2.5) allowed excessive movement of solvent and poor electrochemical yields (capacity fade). Despite having lower voltage efficiencies compared to DAPP2.5, the membrane with an intermediatemore » ion content of 2.0 meq/g (DAPP2.0) exhibited higher coulombic efficiencies (96.4% vs. 89.1%) and electrochemical yields (21.6% vs. 10.9%) after 50 cycles. Crossover of the electroactive species was the primary reason for decreased electrochemical yields. Analysis of the anolyte and catholyte revealed degradation of the electroactive species and formation of a film at the membrane-solution interface. Increases in membrane resistance were attributed to mechanical and thermal aging of the membrane; no chemical change was observed. As a result, improvements in the ionic selectivity and ionic conductivity of the membrane will increase the electrochemical yield and voltage efficiency of future nonaqueous redox flow batteries.« less

Temperature-controlled cross-linking of silver nanoparticles with diels-alder reaction and its application on antibacterial property

NASA Astrophysics Data System (ADS)

Liu, Lian; Yang, Pengfei; Li, Junying; Zhang, Zhiliang; Yu, Xi; Lu, Ling

2017-05-01

Sliver nanoparticles (AgNPs) were synthesized and functionalized with furan group on their surface, followed by the reverse Diels-Alder (DA) reaction with bismaleimide to vary the particle size, so as to give different antibacterial activities. These nanoparticles were characterized using Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), Ultraviolet-Visible (UV-vis), Nanoparticle Size Analyzer and X-Ray Photoelectron Spectroscopy (XPS). It was found that the cross-linking reaction with bismaleimide had a great effect on the size of AgNPs. The size of the AgNPs could be controlled by the temperature of DA/r-DA equilibrium. The antibacterial activity was assessed using the inhibition zone diameter by introducing the particles into a media containing Escherichia coli, Listeria monocytogenes, and Staphylococcus aureus, respectively. It was found that these particles were effective bactericides. Furthermore, the antibacterial activity of the nanoparticles decreased orderly as the particle size enlarged.

Frankia and Alnus rubra canopy roots: an assessment of genetic diversity, propagule availability, and effects on soil nitrogen.

PubMed

Kennedy, Peter G; Schouboe, Jesse L; Rogers, Rachel H; Weber, Marjorie G; Nadkarni, Nalini M

2010-02-01

The ecological importance of microbial symbioses in terrestrial soils is widely recognized, but their role in soils that accumulate in forest canopies is almost entirely unknown. To address this gap, this study investigated the Frankia-Alnus rubra symbiosis in canopy and forest floor roots at Olympic National Park, WA, USA. Sixteen mature A. rubra trees were surveyed and Frankia genetic diversity in canopy and forest floor nodules was assessed with sequence-based nifH analyses. A seedling bioassay experiment was conducted to determine Frankia propagule availability in canopy and forest floor soils. Total soil nitrogen from both environments was also quantified. Nodules were present in the canopies of nine of the 16 trees sampled. Across the study area, Frankia canopy and forest floor assemblages were similar, with both habitats containing the same two genotypes. The composition of forest floor and canopy genotypes on the same tree was not always identical, however, suggesting that dispersal was not a strictly local phenomenon. Frankia seedling colonization was similar in canopy soils regardless of the presence of nodules as well as in forest floor soils, indicating that dispersal was not likely to be a major limiting factor. The total soil nitrogen of canopy soils was higher than that of forest floor soils, but the presence of Frankia nodules in canopy soils did not significantly alter soil nitrogen levels. Overall, this study indicates that the Frankia-A. rubra symbiosis is similar in canopy and forest floor environments. Because canopy roots are exposed to different environmental conditions within very small spatial areas and because those areas can be easily manipulated (e.g., fertilizer or watering treatments), they present microbial ecologists with a unique arena to examine root-microbe interactions.

Flow cytometry, microsatellites and niche models reveal the origins and geographical structure of Alnus glutinosa populations in Europe

PubMed Central

Mandák, Bohumil; Vít, Petr; Krak, Karol; Trávníček, Pavel; Havrdová, Alena; Hadincová, Věroslava; Zákravský, Petr; Jarolímová, Vlasta; Bacles, Cecile Fanny Emilie; Douda, Jan

2016-01-01

Background and Aims Polyploidy in plants has been studied extensively. In many groups, two or more cytotypes represent separate biological entities with distinct distributions, histories and ecology. This study examines the distribution and origins of cytotypes of Alnus glutinosa in Europe, North Africa and western Asia. Methods A combined approach was used involving flow cytometry and microsatellite analysis of 12 loci in 2200 plants from 209 populations combined with species distribution modelling using MIROC and CCSM climatic models, in order to analyse (1) ploidy and genetic variation, (2) the origin of tetraploid A. glutinosa, considering A. incana as a putative parent, and (3) past distributions of the species. Key Results The occurrence of tetraploid populations of A. glutinosa in Europe is determined for the first time. The distribution of tetraploids is far from random, forming two geographically well-delimited clusters located in the Iberian Peninsula and the Dinaric Alps. Based on microsatellite analysis, both tetraploid clusters are probably of autopolyploid origin, with no indication that A. incana was involved in their evolutionary history. A projection of the MIROC distribution model into the Last Glacial Maximum (LGM) showed that (1) populations occurring in the Iberian Peninsula and North Africa were probably interconnected during the LGM and (2) populations occurring in the Dinaric Alps did not exist throughout the last glacial periods, having retreated southwards into lowland areas of the Balkan Peninsula. Conclusions Newly discovered tetraploid populations are situated in the putative main glacial refugia, and neither of them was likely to have been involved in the colonization of central and northern Europe after glacial withdrawal. This could mean that neither the Iberian Peninsula nor the western part of the Balkan Peninsula served as effective refugial areas for northward post-glacial expansion of A. glutinosa. PMID:26467247

Distribution and abundance of phytobenthic communities: Implications for connectivity and ecosystem functioning in a Black Sea Marine Protected Area

NASA Astrophysics Data System (ADS)

Berov, Dimitar; Todorova, Valentina; Dimitrov, Lubomir; Rinde, Eli; Karamfilov, Ventzislav

2018-01-01

The distribution and abundance of macroalgal communities in a Marine Protected Area (MPA) along the Bulgarian Black Sea coast were mapped and quantified, with particular focus on the previously unstudied P. crispa lower-infralittoral communities on Ostrea edulis biogenic reefs. Data from high resolution geophysical substrate mapping were combined with benthic community observations from georeferenced benthic photographic surveys and sampling. Multivariate analysis identified four distinct assemblages of lower-infralittoral macroalgal communities at depths between 10 and 17 m, dominated by Phyllophora crispa, Apoglossum ruscifoluim, Zanardinia typus and Gelidium spp. Maxent software analysis showed distinct preferences of the identified communities to areas with specific ranges of depth, inclination and curvature, with P. crispa more frequently occurring on vertical oyster biogenic reef structures. By combining production rates from literature, biomass measurements and the produced habitat maps, the highest proportion of primary production and DOC release was shown for the upper infralittoral Cystoseira barbata and Cystoseira bosphorica, followed by the production of the lower-infralittoral macroalgae. The observed distribution of P. crispa within the studied MPA was related to the network of Natura 2000 maritime MPAs along the Bulgarian Black Sea coast, which indicated that the connectivity of the populations of the species within the established network is insufficient within this cell of ecosystem functioning.

A role for hydrophobicity in a Diels–Alder reaction catalyzed by pyridyl-modified RNA

PubMed Central

Gagnon, Keith T.; Ju, Show-Yi; Goshe, Michael B.; Maxwell, E. Stuart; Franzen, Stefan

2009-01-01

New classes of RNA enzymes or ribozymes have been obtained by in vitro evolution and selection of RNA molecules. Incorporation of modified nucleotides into the RNA sequence has been proposed to enhance function. DA22 is a modified RNA containing 5-(4-pyridylmethyl) carboxamide uridines, which has been selected for its ability to promote a Diels–Alder cycloaddition reaction. Here, we show that DA_TR96, the most active member of the DA22 RNA sequence family, which was selected with pyridyl-modified nucleotides, accelerates a cycloaddition reaction between anthracene and maleimide derivatives with high turnover. These widely used reactants were not used in the original selection for DA22 and yet here they provide the first demonstration of DA_TR96 as a true multiple-turnover catalyst. In addition, the absence of a structural or essential kinetic role for Cu2+, as initially postulated, and nonsequence-specific hydrophobic interactions with the anthracene substrate have led to a reevaluation of the pyridine modification's role. These findings broaden the catalytic repertoire of the DA22 family of pyridyl-modified RNAs and suggest a key role for the hydrophobic effect in the catalytic mechanism. PMID:19304744

Avoidance of nonhost plants by a bark beetle, Pityogenes bidentatus, in a forest of odors

NASA Astrophysics Data System (ADS)

Byers, John A.; Zhang, Qing-He; Birgersson, Göran

The bark beetle, Pityogenes bidentatus (Coleoptera: Scolytidae), searches in mixed conifer and deciduous forests of northern Europe for suitable branches of its host, Scots pine (Pinus sylvestris). We tested whether odors from several diverse nonhost trees and plants common in the habitat (e.g., mountain ash, Sorbus aucuparia; oak, Quercus robur; alder buckthorn, Frangula alnus; blueberry, Vaccinium myrtillus; raspberry, Rubus idaeus; and grass, Deschampsia flexuosa) would reduce the attraction of the bark beetle to traps releasing its aggregation pheromone components in the field. Volatiles from the leaves or bark of each of these plants significantly reduced the attraction of the beetles to their pheromone. Odors collected from these nonhosts and analyzed by GC/MS contained monoterpenes, sesquiterpenes, and ``green-leaf'' alcohols, several of which (e.g., 1-octene-3-ol and β-caryophyllene) reduced the attraction to pheromone in the field and elicited electroantennographic responses. In the laboratory, reproduction by the beetle was marginal in nonhost Norway spruce, Picea abies, and was absent in the other nonhost trees. Olfactory avoidance of unsuitable nonhosts may have evolved due to advantages in avoiding mistakes during host selection.

Response of Aquatic Hyphomycete Communities to Changes in Heavy Metal Exposure

NASA Astrophysics Data System (ADS)

Sridhar, K. R.; Bärlocher, Felix; Krauss, Gerd-Joachim; Krauss, Gudrun

2005-02-01

Decomposition of Alnus glutinosa (alder) leaves was studied in a severely (site H4) and a moderately (site H8) heavy metal polluted stream in the former copper shale mining district of Mansfeld, Central Germany. Leaves at H8 had reduced fungal diversity and spore production but a high exponential decay rate (k = 0.065). No further mass loss of leaves occurred at H4 after 4-6 weeks, and fungal diversity and spore production were lower than in H8. Decay and sporulation rates gradually increased to values of H8 control leaves in leaves preincubated in H4 and then transferred to H8. These increases correlated with the invasion of transplanted leaves by Tetracladium marchalianum and Tricladium angulatum. In the reverse transplant experiment (H8 to H4), mass loss appeared to stop immediately. Sporulation rates also declined, but remained consistently above levels in H4 control leaves. Leaves precolonized in the laboratory by one of three aquatic hyphomycete species exhibited increased decay rates in both streams. Sporulation rates on these leaves were greater than those of control leaves in H4, but smaller than those of control leaves in H8.

Linking Forests and Fish: The Relationship Between Productivities of Salmonids and Forest Stands in Northern California

NASA Astrophysics Data System (ADS)

Wilzbach, P.; Frazey, S.

2005-05-01

Productivities of resident salmonid populations, upland, and riparian areas in 25 small watersheds of coastal northern California were estimated and compared to determine if: 1) upland site productivity predicted riparian site productivity; 2) either upland or riparian site productivity predicted salmonid productivity; and 3) other parameters explained more of the variance in salmonid productivity than upland or riparian site productivity. Salmonid productivity was indexed by total salmonid biomass, length of age 1 fish, and percent habitat saturation. Upland and riparian site productivities were estimated using site indices for redwood (Sequoia sempervirens) and red alder (Alnus rubra), respectively. Upland and riparian site indices were correlated, but neither factor contributed to the best approximating models of salmonid biomass or fish length at age one. Salmonid biomass was best described by a positive relationship with drainage area, and length at age was best described by a positive relationship with percent of riparian hardwoods. Percent habitat saturation was not well described by any of the models constructed. Lack of a relationship between upland conifer and salmonid productivity suggests that management of land for timber productivity and component streams for salmonid production in these sites will require separate, albeit integrated, strategies.

The skin prick test – European standards

PubMed Central

2013-01-01

Skin prick testing is an essential test procedure to confirm sensitization in IgE-mediated allergic disease in subjects with rhinoconjunctivitis, asthma, urticaria, anapylaxis, atopic eczema and food and drug allergy. This manuscript reviews the available evidence including Medline and Embase searches, abstracts of international allergy meetings and position papers from the world allergy literature. The recommended method of prick testing includes the appropriate use of specific allergen extracts, positive and negative controls, interpretation of the tests after 15 – 20 minutes of application, with a positive result defined as a wheal ≥3 mm diameter. A standard prick test panel for Europe for inhalants is proposed and includes hazel (Corylus avellana), alder (Alnus incana), birch (Betula alba), plane (Platanus vulgaris), cypress (Cupressus sempervirens), grass mix (Poa pratensis, Dactilis glomerata, Lolium perenne, Phleum pratense, Festuca pratensis, Helictotrichon pretense), Olive (Olea europaea), mugwort (Artemisia vulgaris), ragweed (Ambrosia artemisiifolia), Alternaria alternata (tenuis), Cladosporium herbarum, Aspergillus fumigatus, Parietaria, cat, dog, Dermatophagoides pteronyssinus, Dermatophagoides farinae, and cockroach (Blatella germanica). Standardization of the skin test procedures and standard panels for different geographic locations are encouraged worldwide to permit better comparisons for diagnostic, clinical and research purposes. PMID:23369181

Plant responses to elevated atmospheric CO/sub 2/ with emphasis on belowground processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Norby, R.J.; Luxmoore, R.J.; O'Neill, E.G.

1984-12-01

Consideration of the interrelationships between carbon, water, and nutrient pathways in soil-plant systems has led to the hypothesis that stimulation of root and rhizosphere processes by elevated levels of CO/sub 2/ will increase nutrient availability and lead to an increase in plant growth. Several experiments were conducted to investigate the effects of CO/sub 2/ concentration on carbon allocation, root exudation, nitrogen utilization, and microbial responses, as well as overall plant growth and nutrient utilization. Increases in the growth of yellow-poplar (Liriodendron tulipifera L.) seedlings in response to elevated CO/sub 2/ were demonstrated even when the plants were under apparent nutrientmore » limitation in a forest soil. The proportion of photosynthetically fixed carbon that was allocated to the roots of yellow-poplar and hazel alder (Alnus serrulata (Ait.) Willd.) seedlings was greater at 700 ppM CO/sub 2/ than at ambient CO/sub 2/. Exudation of carbon from yellow-poplar roots also tended to be higher in elevated CO/sub 2/. Responses of rhizosphere microbial populations to elevated CO/sub 2/ were inconsistent, but there was a trend toward relatively fewer ammonium oxidizers, nitrite oxidizers, and phosphate solubilizers in the rhizosphere population of yellow-poplar seedlings grown in 700 ppM CO/sub 2/ compared to that of seedlings grown in ambient CO/sub 2/. Other observed trends included increased nodulation and nitrogenase activity and decreased nitrate reductase activity in hazel alder seedlings in elevated CO/sub 2/. Net uptake of some essential plant nutrients, aluminum, and other trace metals by Virginia pine (Pinus virginiana Mill.) increased with increasing CO/sub 2/ concentration. There was less leaching of some nutrients from soil-plant systems with Virginia pine and yellow-poplar seedlings but increased leaching of zinc. 123 references, 16 figures, 17 tables.« less

Diels-Alder Trapping of Photochemically Generated o-Quinodimethane Intermediates: An Alternative Route to Photocured Polymer Film Development

NASA Technical Reports Server (NTRS)

Tyson, Daniel S.; Ilhan, Faysal; Meador, Mary Ann B.; Smith, Dee Dee; Scheiman, Daniel A.; Meador, Michael A.

2004-01-01

Photolysis of o-methylphenyl ketones generates bis-o-quinodimethane intermediates that can be trapped in situ by dienophiles through Diels-Alder cycloadditions. This well-known photochemical process is applied to a series of six new photoreactive monomers containing bis-(o-methylphenyl ketone) functionalities combined with diacrylate and triacrylate ester monomers for the development of acrylic ester copolymer blends. Irradiation of cyclohexanone solutions of the bis-(o-methylphenyl ketone)s and acrylate esters produce thin polymer films. Solid state 13C NMR data indicated 47- 100% reaction of the bis-(o-methylphenyl ketone)s, depending on experimental conditions, to yield the desired products. DSC and TGA analyses were performed to determine the glass transition temperature, T,, and onset of decomposition, Td, of the resulting polymer films. A statistical Design of Experiments approach was used to obtain a systematic understanding of the effects of experimental variables on the extent of polymerization and the final polymer properties.

Prediction of the chemo- and regioselectivity of Diels-Alder reactions of o-benzoquinone derivatives with thiophenes by means of DFT-based reactivity indices

NASA Astrophysics Data System (ADS)

Ghomri, Amina; Mekelleche, Sidi Mohamed

2014-03-01

Global and local reactivity indices derived from density functional theory were used to elucidate the regio- and chemoselectivity of Diels-Alder reactions of masked o-benzoquinones with thiophenes acting as dienophiles. The polarity of the studied reactions is evaluated in terms of the difference of electrophilicity powers between the diene and dienophile partners. Preferential cyclisation modes of these cycloadditions are predicted using Domingo's polar model based on the local electrophilicity index, ωk, of the electrophile and the local nucleophilicity index, Nuk, of the nucleophile. The theoretical calculations, carried out at the B3LYP/6-311G(d,p) level of theory, are in good agreement with experimental findings.

Full cell study of Diels Alder poly(phenylene) anion and cation exchange membranes in vanadium redox flow batteries

DOE PAGES

Pezeshki, Alan M.; Fujimoto, Cy; Sun, Che -Nan; ...

2015-11-14

In this paper, we report on the performance of Diels Alder poly(phenylene) membranes in vanadium redox flow batteries. The membranes were functionalized with quaternary ammonium groups to form an anion exchange membrane (QDAPP) and with sulfonic acid groups to form a cation exchange membrane (SDAPP). Both membrane classes showed similar conductivities in the battery environment, suggesting that the ion conduction mechanism in the material is not strongly affected by the moieties along the polymer backbone. The resistance to vanadium permeation in QDAPP was not improved relative to SDAPP, further suggesting that the polarity of the functional groups do not playmore » a significant role in the membrane materials tested. Both QDAPP and SDAPP outperformed Nafion membranes in cycling tests, with both achieving voltage efficiencies above 85% while maintaining 95% coulombic efficiency while at a current density of 200 mA/cm 2.« less

Diels-Alder and Stille Coupling Approach for the Short Protecting-Group-Free Synthesis of Mycophenolic Acid, Its Phenylsulfenyl and Phenylselenyl Analogues, and Reactive Oxygen Species (ROS) Probing Capacity in Water.

PubMed

Halle, Mahesh B; Yudhistira, Tesla; Lee, Woo-Hyun; Mulay, Sandip V; Churchill, David G

2018-06-15

A short, protecting-group-free synthesis is achieved. The synthesis is step-efficient and general. A Diels-Alder and Stille cross-coupling approach includes key transformations, allowing for a competitive synthesis which involves a rare halophenol Stille cross-coupling study. The phenylselenyl and phenylsulfenyl analogues were prepared as novel compounds in good overall yield. The applicability of one of the intermediates as a potential probe for reactive oxygen species (ROS) in water is investigated.

Mild and modular surface modification of cellulose via hetero Diels-Alder (HDA) cycloaddition.

PubMed

Goldmann, Anja S; Tischer, Thomas; Barner, Leonie; Bruns, Michael; Barner-Kowollik, Christopher

2011-04-11

A combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and hetero Diels-Alder (HDA) cycloaddition was used to effect, under mild (T ≈ 20 °C), fast, and modular conditions, the grafting of poly(isobornyl acrylate) (M(n) = 9800 g mol(-1), PDI = 1.19) onto a solid cellulose substrate. The active hydroxyl groups expressed on the cellulose fibers were converted to tosylate leaving groups, which were subsequently substituted by a highly reactive cyclopentadienyl functionality (Cp). By employing the reactive Cp-functionality as a diene, thiocarbonyl thio-capped poly(isobornyl acrylate) synthesized via RAFT polymerization (mediated by benzyl pyridine-2-yldithioformiate (BPDF)) was attached to the surface under ambient conditions by an HDA cycloaddition (reaction time: 15 h). The surface-modified cellulose samples were analyzed in-depth by X-ray photoelectron spectroscopy, scanning electron microscopy, elemental analysis, Fourier transform infrared (FT-IR) spectroscopy as well as Fourier transform infrared microscopy employing a focal plane array detector for imaging purposes. The analytical results provide strong evidence that the reaction of suitable dienophiles with Cp-functional cellulose proceeds under mild reaction conditions (T ≈ 20 °C) in an efficient fashion. In particular, the visualization of individual modified cellulose fibers via high-resolution FT-IR microscopy corroborates the homogeneous distribution of the polymer film on the cellulose fibers.

Why bistetracenes are much less reactive than pentacenes in Diels-Alder reactions with fullerenes.

PubMed

Cao, Yang; Liang, Yong; Zhang, Lei; Osuna, Sílvia; Hoyt, Andra-Lisa M; Briseno, Alejandro L; Houk, K N

2014-07-30

The Diels-Alder (DA) reactions of pentacene (PT), 6,13-bis(2-trimethylsilylethynyl)pentacene (TMS-PT), bistetracene (BT), and 8,17-bis(2-trimethylsilylethynyl)bistetracene (TMS-BT) with the [6,6] double bond of [60]fullerene have been investigated by density functional theory calculations. Reaction barriers and free energies have been obtained to assess the effects of frameworks and substituent groups on the DA reactivity and product stability. Calculations indicate that TMS-BT is about 5 orders of magnitude less reactive than TMS-PT in the reactions with [60]fullerene. This accounts for the observed much higher stability of TIPS-BT than TIPS-PT when mixed with PCBM. Surprisingly, calculations predict that the bulky silylethynyl substituents of TMS-PT and TMS-BT have only a small influence on reaction barriers. However, the silylethynyl substituents significantly destabilize the corresponding products due to steric repulsions in the adducts. This is confirmed by experimental results here. Architectures of the polycyclic aromatic hydrocarbons (PAHs) play a crucial role in determining both the DA barrier and the adduct stability. The reactivities of different sites in various PAHs are related to the loss of aromaticity, which can be predicted using the simple Hückel molecular orbital localization energy calculations.

Catalysis in the Diels-Alder Cycloaddition of Biomass-Derived Furan and Methyl Acrylate by Transition Metal Oxide Surfaces.

NASA Astrophysics Data System (ADS)

Salavati-Fard, Taha; Jenness, Glen; Caratzoulas, Stavros; Doren, Douglas

Using computational methods, the catalytic effects of oxide surfaces on the Diels-Alder reaction between biomass-derived furan and methyl acrylate are investigated. The cycloadduct can be dehydrated later to produce methyl benzoic which is an important step toward benzoic acid production. Different systems such as clean, partially hydroxylated and fully hydroxylated ZrO2 are considered. The Langmuir and Eley-Rideal mechanisms are studied, as well. Our calculations show that the oxide surfaces catalyze the reaction significantly through the interaction of metal sites with the electron-poor reactant. The calculations are interpreted by making use of the total and projected electronic density of states and band structure of the catalyst. This material is based on work supported as part of the Catalysis Center for Energy Innovation, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001004.

(125)I-Tetrazines and Inverse-Electron-Demand Diels-Alder Chemistry: A Convenient Radioiodination Strategy for Biomolecule Labeling, Screening, and Biodistribution Studies.

PubMed

Albu, Silvia A; Al-Karmi, Salma A; Vito, Alyssa; Dzandzi, James P K; Zlitni, Aimen; Beckford-Vera, Denis; Blacker, Megan; Janzen, Nancy; Patel, Ramesh M; Capretta, Alfredo; Valliant, John F

2016-01-20

A convenient method to prepare radioiodinated tetrazines was developed, such that a bioorthogonal inverse electron demand Diels-Alder reaction can be used to label biomolecules with iodine-125 for in vitro screening and in vivo biodistribution studies. The tetrazine was prepared by employing a high-yielding oxidative halo destannylation reaction that concomitantly oxidized the dihydrotetrazine precursor. The product reacts quickly and efficiently with trans-cyclooctene derivatives. Utility was demonstrated through antibody and hormone labeling experiments and by evaluating products using standard analytical methods, in vitro assays, and quantitative biodistribution studies where the latter was performed in direct comparison to Bolton-Hunter and direct iodination methods. The approach described provides a convenient and advantageous alternative to conventional protein iodination methods that can expedite preclinical development and evaluation of biotherapeutics.

Solution-phase parallel synthesis of hexahydro-1H-isoindolone libraries via tactical combination of Cu-catalyzed three-component coupling and Diels-Alder reactions.

PubMed

Zhang, Lei; Lushington, Gerald H; Neuenswander, Benjamin; Hershberger, John C; Malinakova, Helena C

2008-01-01

Parallel solution-phase synthesis of combinatorial libraries of hexahydro-1 H-isoindolones exploiting a novel "tactical combination" of Cu-catalyzed three-component coupling and Diels-Alder reactions was accomplished. Three distinct libraries consisting of 24 members (library I), 60 members (library II), and 32 members (library III) were constructed. Variation of three substituents on the isoindolone scaffold in library I was exclusively achieved by the choice of the building blocks. In the syntheses of libraries II and III, sublibraries of isoindolone scaffolds were prepared initially in a one-pot/two-step process and were further diversified via Pd-catalyzed Suzuki cross-coupling reaction with boronic acids at two different diversification points. The Lipinski profiles and calculated ADME properties of the compounds are also reported.

Self-healable interfaces based on thermo-reversible Diels-Alder reactions in carbon fiber reinforced composites.

PubMed

Zhang, W; Duchet, J; Gérard, J F

2014-09-15

Thermo-reversible Diels-Alder (DA) bonds formed between maleimide and furan groups have been used to generate an interphase between carbon fiber surface and an epoxy matrix leading to the ability of interfacial self-healing in carbon:epoxy composite materials. The maleimide groups were grafted on an untreated T700 carbon fiber from a three step surface treatment: (i) nitric acid oxidization, (ii) tetraethylenepentamine amination, and (iii) bismaleimide grafting. The furan groups were introduced in the reactive epoxy system from furfuryl glycidyl ether. The interface between untreated carbon fiber and epoxy matrix was considered as a reference. The interfacial shear strength (IFSS) was evaluated by single fiber micro-debonding test. The debonding force was shown to have a linear dependence with embedded length. The highest healing efficiency calculated from the debonding force was found to be about 82% more compared to the value for the reference interface. All the interphases designed with reversible DA bonds have a repeatable self-healing ability. As after the fourth healing, they can recover a relatively high healing efficiency (58% for the interphase formed by T700-BMI which is oxidized for 60 min during the first treatment step). Copyright © 2014 Elsevier Inc. All rights reserved.

Stages of the development of alluvial soils in the Bikin River valley (the Amur River basin) in the Middle and Late Holocene

NASA Astrophysics Data System (ADS)

Nazarkina, A. V.; Belyanin, P. S.

2014-05-01

The evolution of alluvial soils in the Bikin River basin in the Middle and the Late Holocene is discussed. On the basis of biostratigraphic data, four pollen zones have been identified in the soils: Pinus koraiensis- Picea, Pinus koraiensis- Quercus- Sphagnum, Betula- Alnus- Alnaster, and Quercus. A set of soil characteristics (texture, acid-base properties, and the organic matter content and group composition) have also been determined. These data allow us to distinguish between four stages of alluvial soil formation in the Bikin River basin. They characterize humus-forming conditions in the Middle and the Late Holocene. Reconstruction of ancient vegetation conditions makes it possible to conclude that climatic fluctuations were synchronous with changes in the soil characteristics. During the Holocene climatic optimum, humus was formed in a slightly acid medium, and humic acids predominated. In cold periods with increased precipitation, fulvic acids predominated in the composition of humus, and the portion of insoluble residue was high because of the more acid medium. The stages of alluvial pedogenesis in the Bikin River valley follow the sedimentation model of soil evolution. Alluvial gray humus soils evolved from typical gray humus soils under meadow communities during warm periods to gleyic and gleyed soils under birch shrubs and alder groves in colder and wetter periods.

Pollen, vegetation, and climate relationships along the Dalton Highway, Alaska, USA: a basis for holocene paleoecological and paleoclimatic studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Short, S.K.; Andrews, J.T.; Webber, P.J.

The Dalton Highway extends from Fairbanks, in the interior of Alaska, to Prudhoe Bay on the Arctic Coastal Plain. Over this 600-km transect, July temperatures vary from 17 to 5/sup 0/C. Studies of vegetation along the Dalton Highway identified nine major zones. During the vegetation survey moss polsters were collected within the survey quadrats. Two hundred and nineteen individual moss polsters document regional variations in the modern pollen spectra along this vegetation/climate transect. Treeline is distinguished by a change from dominance by spruce and shrub (especially alder) pollen to the south to herb and shrub (especially willow) pollen dominance tomore » the north; a shift from high modern pollen concentration values to very low values is also noted. Discriminant analysis indicated that the vegetation zones are also defined by different pollen assemblages, suggesting that former changes in vegetation during the Holocene, as recorded in peat deposits, could be interpreted from pollen diagrams. Transfer functions were developed to examine the statistical association between the modern pollen rain and several climatic parameters. The correlation between pollen taxa and mean July temperature was r = 0.84. The most important taxa in the equation are Picea, Alnus, Pinus, Sphagnum, and Betula. 59 references, 7 figures, 4 tables.« less

Densities of breeding birds and changes in vegetation in an alaskan boreal forest following a massive disturbance by spruce beetles

USGS Publications Warehouse

Matsuoka, S.M.; Handel, C.M.; Ruthrauff, D.R.

2001-01-01

We examined bird and plant communities among forest stands with different levels of spruce mortality following a large outbreak of spruce beetles (Dendroctonus rufipennis (Kirby)) in the Copper River Basin, Alaska. Spruce beetles avoided stands with black spruce (Picea mariana) and selectively killed larger diameter white spruce (Picea glauca), thereby altering forest structure and increasing the dominance of black spruce in the region. Alders (Alnus sp.) and crowberry (Empetrum nigrum) were more abundant in areas with heavy spruce mortality, possibly a response to the death of overstory spruce. Grasses and herbaceous plants did not proliferate as has been recorded following outbreaks in more coastal Alaskan forests. Two species closely tied to coniferous habitats, the tree-nesting Ruby-crowned Kinglet (Regulus calendula) and the red squirrel (Tamiasciurus hudsonicus), a major nest predator, were less abundant in forest stands with high spruce mortality than in low-mortality stands. Understory-nesting birds as a group were more abundant in forest stands with high levels of spruce mortality, although the response of individual bird species to tree mortality was variable. Birds breeding in stands with high spruce mortality likely benefited reproductively from lower squirrel densities and a greater abundance of shrubs to conceal nests from predators.

Fluorescence responses and photosynthetic rates of sunlit and shaded leaves of Italian alpine forest species: Summer 1997 ATOM-LIFT campaign

NASA Astrophysics Data System (ADS)

Kim, Moon S.; Cecchi, Giovanna; Chappelle, Emmett W.; Bazzani, Marco; McMurtrey, James E., III; Corp, Lawrence A.; Sandu, R.; Tirelli, Daniele

1998-07-01

Terrestrial vegetation studies were carried out in the Italian Northeastern Alps in Val Visdende. The measurement site was 15 Kilometers Northeast of the town of St. Stefano di Calore (Belluno), Italy. Measurements were acquired on a wooded site at the Italian Department of Forestry Station on species native to the Italian Alps. The species included spruce (Picea abies) and alder (Alnus incana) trees. Characterization was also made of the fluorescence responses of several under-story species such as Dactylorhiza fuchsii of the Orchidaceae family, Caltha palustris and Ranunculus ficaria of the Ranuncolcee family, and Trifolium pratense and Trifolium repens of the Leguminosae family. Terrestrial vegetation monitoring was conducted with the Italian FLIDAR remote sensing instrument mounted in a mobile van, the NASA/USDA Fluorescence Imaging System (FIS), and the Spectron SE-590 for optical properties. Photosynthetic CO2 gas exchange rates we made with LI-COR 6400 infrared gas analyzer. Pigments from the samples were extracted and analyzed with a Perkin Elmer Lamda 7 Spectrometer to determine pigment concentrations. Fluorescence responses were collected from vegetation samples grown under different ambient light regimes of sun-lit versus shaded. The vegetation showed different fluorescence characteristics. A fluorescence algorithm, (F740/F680)/F550, and rate of photosynthesis showed a strong linear relationship.

Testing the link between community structure and function for ectomycorrhizal fungi involved in a global tripartite symbiosis.

PubMed

Walker, Jennifer K M; Cohen, Hannah; Higgins, Logan M; Kennedy, Peter G

2014-04-01

Alnus trees associate with ectomycorrhizal (ECM) fungi and nitrogen-fixing Frankia bacteria and, although their ECM fungal communities are uncommonly host specific and species poor, it is unclear whether the functioning of Alnus ECM fungal symbionts differs from that of other ECM hosts. We used exoenzyme root tip assays and molecular identification to test whether ECM fungi on Alnus rubra differed in their ability to access organic phosphorus (P) and nitrogen (N) when compared with ECM fungi on the non-Frankia host Pseudotsuga menziesii. At the community level, potential acid phosphatase (AP) activity of ECM fungal root tips from A. rubra was significantly higher than that from P. menziesii, whereas potential leucine aminopeptidase (LA) activity was significantly lower for A. rubra root tips at one of the two sites. At the individual species level, there was no clear relationship between ECM fungal relative root tip abundance and relative AP or LA enzyme activities on either host. Our results are consistent with the hypothesis that ECM fungal communities associated with Alnus trees have enhanced organic P acquisition abilities relative to non-Frankia ECM hosts. This shift, in combination with the chemical conditions present in Alnus forest soils, may drive the atypical structure of Alnus ECM fungal communities. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Supramolecular hydrogel formation between chitosan and hydroxypropyl β-cyclodextrin via Diels-Alder reaction and its drug delivery.

PubMed

Zhang, Mengke; Wang, Jinpeng; Jin, Zhengyu

2018-07-15

Chitosan-cyclodextrin hydrogel (CFCD) was prepared via Diels-Alder reaction between furfural functionalized chitosan (CF) and N-maleoyl alanine functionalized hydroxypropyl β-cyclodextrin (HPCD-AMI) in aqueous media without any catalyst or initiator. The CF and HPCD-AMI were confirmed by Fourier transform infrared spectroscopy and 1 H nuclear magnetic resonance spectroscopy. The resultant CFCD hydrogel was characterized in terms of thermal peripteries, microstructure, rheology behavior, and swelling capacity. The rheology analysis found that the storage modulus G' ranged from 1pa to 1200pa as the degree of furfural substitute on chitosan increased from 2.6% to 28.3%, indicating the hydrogel strength can be tuned readily by reaction stoichiometry. The swelling behaviors proved that CFCD hydrogel was pH-responsive with low swelling capacity, which would be preferable for drug delivery. Drug adsorption analysis showed the introduction of cyclodextrin into CFCD hydrogels promoted drug adsorption capacity. In addition, methyl orange cumulative release in PBS buffer was only 48.85% after 24h, suggesting CFCD hydrogel had good sustained release capacity on the loaded drug. Copyright © 2018 Elsevier B.V. All rights reserved.

N-(furfural) chitosan hydrogels based on Diels-Alder cycloadditions and application as microspheres for controlled drug release.

PubMed

Montiel-Herrera, Marcelino; Gandini, Alessandro; Goycoolea, Francisco M; Jacobsen, Neil E; Lizardi-Mendoza, Jaime; Recillas-Mota, Maricarmen; Argüelles-Monal, Waldo M

2015-09-05

In this study, chitosan was chemically modified by reductive amination in a two-step process. The synthesis of N-(furfural) chitosan (FC) was confirmed by FT-IR and (1)H NMR analysis, and the degrees of substitution were estimated as 8.3 and 23.8%. The cross-linkable system of bismaleimide (BM) and FC shows that FC shared properties of furan-maleimide chemistry. This system produced non-reversible hydrogel networks by Diels-Alder cycloadditions at 85 °C. The system composed of BM and FC (23.8% substitution) generated stronger hydrogel networks than those of FC with an 8.3% degree of substitution. Moreover, the FC-BM system was able to produce hydrogel microspheres. Environmental scanning electron microscopy revealed the surface of the microspheres to be non-porous with small protuberances. In water, the microspheres swelled, increasing their volume by 30%. Finally, microspheres loaded with methylene blue were able to release the dye gradually, obeying second-order kinetics for times less than 600 min. This behavior suggests that diffusion is governed by the relaxation of polymer chains in the swelled state, thus facilitating drug release outside the microspheres. Copyright © 2015 Elsevier Ltd. All rights reserved.

The [2 + 2] Cycloaddition-Retroelectrocyclization and [4 + 2] Hetero-Diels-Alder Reactions of 2-(Dicyanomethylene)indan-1,3-dione with Electron-Rich Alkynes: Influence of Lewis Acids on Reactivity.

PubMed

Donckele, Etienne J; Finke, Aaron D; Ruhlmann, Laurent; Boudon, Corinne; Trapp, Nils; Diederich, François

2015-07-17

The reaction of electrophilic 2-(dicyanomethylene)indan-1,3-dione (DCID) with substituted, electron-rich alkynes provides two classes of push-pull chromophores with interesting optoelectronic properties. The formal [2 + 2] cycloaddition-retroelectrocyclization reaction at the exocyclic double bond of DCID gives cyanobuta-1,3-dienes, and the formal [4 + 2] hetero-Diels-Alder (HDA) reaction at an enone moiety of DCID generates fused 4H-pyran heterocycles. Both products can be obtained in good yield and excellent selectivity by carefully tuning the reaction conditions; in particular, the use of Lewis acids dramatically enhances formation of the HDA adduct.

Spiroketals of Pestalotiopsis fici provide evidence for a biosynthetic hypothesis involving diversified Diels-Alder reaction cascades.

PubMed

Liu, Ling; Li, Yan; Li, Li; Cao, Ya; Guo, Liangdong; Liu, Gang; Che, Yongsheng

2013-04-05

Chloropestolides B-G (1-6), six new metabolites featuring the chlorinated spiro[benzo[d][1,3]dioxine-2,7'-bicyclo[2.2.2]octane]-4,8'-dione (1-3) and spiro[benzo[d][1,3]dioxine-2,1'-naphthalene]-2',4-dione (4-6) skeletons, and their putative biosynthetic precursor dechloromaldoxin (7) were isolated from the scale-up fermentation cultures of the plant endophytic fungus Pestalotiopsis fici . The structures of 1-7 were determined mainly by NMR experiments. The absolute configurations of 1-3 were deduced by analogy to the previously isolated metabolites from the same fungus (9 and 13-18), whereas those of 4, 5, and 7 were assigned by electronic circular dichroism (ECD) calculations. Structurally, the spiroketal skeletons found in 1-3 and 4-6 could be derived from 2,6-dihydroxy-4-methylbenzoic acid with chlorinated bicyclo[2.2.2]oct-2-en-5-one and 4a,5,8,8a-tetrahydronaphthalen-2(1H)-one, respectively. Biogenetically, compounds 1-6 were derived from the same Diels-Alder precursors as the previously isolated 9 and 12-18. In addition, compounds 2 and 3 were proposed as the biosynthetic intermediates of 17 and 16, respectively. Compound 1 was cytotoxic to three human tumor cell lines.

Microwave-assisted intramolecular dehydrogenative Diels-Alder reactions for the synthesis of functionalized naphthalenes/solvatochromic dyes.

PubMed

Kocsis, Laura S; Benedetti, Erica; Brummond, Kay M

2013-04-01

Functionalized naphthalenes have applications in a variety of research fields ranging from the synthesis of natural or biologically active molecules to the preparation of new organic dyes. Although numerous strategies have been reported to access naphthalene scaffolds, many procedures still present limitations in terms of incorporating functionality, which in turn narrows the range of available substrates. The development of versatile methods for direct access to substituted naphthalenes is therefore highly desirable. The Diels-Alder (DA) cycloaddition reaction is a powerful and attractive method for the formation of saturated and unsaturated ring systems from readily available starting materials. A new microwave-assisted intramolecular dehydrogenative DA reaction of styrenyl derivatives described herein generates a variety of functionalized cyclopenta[b]naphthalenes that could not be prepared using existing synthetic methods. When compared to conventional heating, microwave irradiation accelerates reaction rates, enhances yields, and limits the formation of undesired byproducts. The utility of this protocol is further demonstrated by the conversion of a DA cycloadduct into a novel solvatochromic fluorescent dye via a Buchwald-Hartwig palladium-catalyzed cross-coupling reaction. Fluorescence spectroscopy, as an informative and sensitive analytical technique, plays a key role in research fields including environmental science, medicine, pharmacology, and cellular biology. Access to a variety of new organic fluorophores provided by the microwave-assisted dehydrogenative DA reaction allows for further advancement in these fields.

Microwave-assisted Intramolecular Dehydrogenative Diels-Alder Reactions for the Synthesis of Functionalized Naphthalenes/Solvatochromic Dyes

PubMed Central

Kocsis, Laura S.; Benedetti, Erica; Brummond, Kay M.

2013-01-01

Functionalized naphthalenes have applications in a variety of research fields ranging from the synthesis of natural or biologically active molecules to the preparation of new organic dyes. Although numerous strategies have been reported to access naphthalene scaffolds, many procedures still present limitations in terms of incorporating functionality, which in turn narrows the range of available substrates. The development of versatile methods for direct access to substituted naphthalenes is therefore highly desirable. The Diels-Alder (DA) cycloaddition reaction is a powerful and attractive method for the formation of saturated and unsaturated ring systems from readily available starting materials. A new microwave-assisted intramolecular dehydrogenative DA reaction of styrenyl derivatives described herein generates a variety of functionalized cyclopenta[b]naphthalenes that could not be prepared using existing synthetic methods. When compared to conventional heating, microwave irradiation accelerates reaction rates, enhances yields, and limits the formation of undesired byproducts. The utility of this protocol is further demonstrated by the conversion of a DA cycloadduct into a novel solvatochromic fluorescent dye via a Buchwald-Hartwig palladium-catalyzed cross-coupling reaction. Fluorescence spectroscopy, as an informative and sensitive analytical technique, plays a key role in research fields including environmental science, medicine, pharmacology, and cellular biology. Access to a variety of new organic fluorophores provided by the microwave-assisted dehydrogenative DA reaction allows for further advancement in these fields. PMID:23609566

Winter behavior and ecology of the Alder Flycatcher (Empidonax alnorum) in Peru

USGS Publications Warehouse

Foster, M.S.

2007-01-01

The winter ecology and behavior of Alder Flycatchers (Empidonax alnorum) were studied along the Manu, a white-water meander river in Manu National Park, Madre de Dios, Peru during October and November, 1993 to 1997. The birds occupied territories in primary-succession habitats on growing point bars. They were most common in mixed stands of Tessaria integrifolia (Asteraceae) and Gynerium sagittatum (Gramineaceae) interspersed with bare sand areas. The uneven height of the Tessaria canopy, which resulted in openings in the vegetation large enough for the birds to flycatch, was an important habitat feature. Birds obtained insects, which formed about 96% of the diet, by aerial hawking (91%), perch gleaning (6%), and hover gleaning (3%). They also fed on fruit. Territory sizes ranged from 0.04 to 0.25 ha. Of nine territories that we observed closely, six were occupied by two birds each, two by one bird each, and one by three birds. Every territory had one dominant individual who was primarily responsible for territory defense; the other birds were associates. Vocalizations given included the fee-bee-o song, a two-syllable song, and the pit note, which are also given on the breeding grounds. A series of pits given increasingly rapidly signaled a territorial interaction. In aggressive encounters, the birds (1) interacted vocally, remaining on their territories and counter calling or exchanging agitated calls; (2) moved toward a common territorial boundary and engaged in a vocal duel; or (3) the dominant chased intruders out of the territory. Chases were most common when a wave of new birds entered the area. Dominant birds, which sang the full song, were probably adult males. Immature males do not sing a full song, and females are not known to sing in nature. Associate individuals were likely females or young males.

Winter behavior and ecology of the Alder Flycatcher (Empidonax alnorum) in Peru

USGS Publications Warehouse

Foster, M.S.

2007-01-01

The winter ecology and behavior of Alder Flycatchers (Empidonax alnorum) were studied along the Manu, a white-water meander river in Manu National Park, Madre de Dios, Peru?? during October and November, 1993 to 1997. The birds occupied territories in primary-succession habitats on growing point bars. They were most common in mixed stands of Tessaria integrifolia (Asteraceae) and Gynerium sagittatum (Gramineaceae) interspersed with bare sand areas. The uneven height of the Tessaria canopy, which resulted in openings in the vegetation large enough for the birds to flycatch, was an important habitat feature. Birds obtained insects, which formed about 96% of the diet, by aerial hawking (91%), perch gleaning (6%), and hover gleaning (3%). They also fed on fruit. Territory sizes ranged from 0.04 to 0.25 ha. Of nine territories that we observed closely, six were occupied by two birds each, two by one bird each, and one by three birds. Every territory had one dominant individual who was primarily responsible for territory defense; the other birds were associates. Vocalizations given included the fee-bee-o song, a two-syllable song, nd the pit note, which are also given on the breeding grounds. A series of pits given increasingly rapidly signaled a territorial interaction. In aggressive encounters, the birds (1) interacted vocally, remaining on their territories and counter calling or exchanging agitated calls; (2) moved toward a common territorial boundary and engaged in a vocal duel; or (3) the dominant chased intruders out of the territory. Chases were most common when a wave of new birds entered the area. Dominant birds, which sang the full song, were probably adult males. Immature males do not sing a full song, and females are not known to sing in nature. Associate individuals were likely females or young males. ?? The Neotropical Ornithological Society.

Effects of Debris Flows on Stream Ecosystems of the Klamath Mountains, Northern California

NASA Astrophysics Data System (ADS)

Cover, M. R.; Delafuente, J. A.; Resh, V. H.

2006-12-01

We examined the long-term effects of debris flows on channel characteristics and aquatic food webs in steep (0.04-0.06 slope), small (4-6 m wide) streams. A large rain-on-snow storm event in January 1997 resulted in numerous landslides and debris flows throughout many basins in the Klamath Mountains of northern California. Debris floods resulted in extensive impacts throughout entire drainage networks, including mobilization of valley floor deposits and removal of vegetation. Comparing 5 streams scoured by debris flows in 1997 and 5 streams that had not been scoured as recently, we determined that debris-flows decreased channel complexity by reducing alluvial step frequency and large woody debris volumes. Unscoured streams had more diverse riparian vegetation, whereas scoured streams were dominated by dense, even-aged stands of white alder (Alnus rhombiflia). Benthic invertebrate shredders, especially nemourid and peltoperlid stoneflies, were more abundant and diverse in unscoured streams, reflecting the more diverse allochthonous resources. Debris flows resulted in increased variability in canopy cover, depending on degree of alder recolonization. Periphyton biomass was higher in unscoured streams, but primary production was greater in the recently scoured streams, suggesting that invertebrate grazers kept algal assemblages in an early successional state. Glossosomatid caddisflies were predominant scrapers in scoured streams; heptageniid mayflies were abundant in unscoured streams. Rainbow trout (Oncorhynchus mykiss) were of similar abundance in scoured and unscoured streams, but scoured streams were dominated by young-of-the-year fish while older juveniles were more abundant in unscoured streams. Differences in the presence of cold-water (Doroneuria) versus warm-water (Calineuria) perlid stoneflies suggest that debris flows have altered stream temperatures. Debris flows have long-lasting impacts on stream communities, primarily through the cascading effects of

A 26,600 yr record of climate and vegetation from Rice Lake in the Eel River drainage of the northern California Coast Range

NASA Astrophysics Data System (ADS)

Heusser, L. E.

2014-12-01

Rice Lake, (40'41" N; 123'30" W, 1109 m elev.) lies in the transition zone of the precipitation dipole in the western United States, which is reflected by the present vegetation - a mosaic of mesic northern mixed hardwood-evergreen forests (Quercus spp., Pinus spp., Calocedrus/Juniperus) and more arid southern oak foothill woodlands (Quercus spp.) that borders the westernmost edge of coastal redwoods (Sequoia sempervirens) forest. The site, which lies on the active Lake Mountain fault zone, is now a large (~15 ha) sagpond that dries in summer. Between ~26,600 yr - ~15,000 yr, a permanent lake with aquatic vegetation (Isoetes) occupied the core site. Montane conifer forests, with pine (Pinus, spp.), mountain hemlock (Tsuga mertensiana), spruce (Picea spp), and western hemlock (T. heterophylla) covered the region. Climatic parameters of modern montane coniferous forest and the continued presence of aquatic vegetation (Isoetes) suggest higher precipitation and lower temperatures during the last glacial. Charcoal (fire event frequency) was minimal. Rapid oscillations of oak, the riparian alder (Alnus), pine, Cupressaceae (Juniperus, Calocedrus), Douglas fir (Pseudotsuga menzeii), and fir (Abies) characterize the deglacial, and reflect rapid changes in precipitation and temperatures, e.g, Bølling-Allerød warming and Younger Dryas cooling. Between ~15,000 yr and ~13,000 yr, aquatic vegetation of the lake abruptly decreased. Expansion of oak, tanoak (Lithocarpus), shrubs (cf. Ceanothus) and decline of pine and montane conifers, along with the development of marshes with Typha and Cyperaceae on the former lakebed, imply early Holocene warming and decreasing precipitation. This is supported by an increase in charcoal, which is attributed to forest fires. Between ~5,000 yr - ~6,000 yr, a short interval of increased precipitation (inferred from a peak in alder and decrease in Cupressaceae) initiates the development of modern mixed hardwood-evergreen forest. Correlative data

Vegetation and climate variability during the Last Interglacial evidenced in the pollen record from Lake Baikal

NASA Astrophysics Data System (ADS)

Granoszewski, W.; Demske, D.; Nita, M.; Heumann, G.; Andreev, A. A.

2005-04-01

A pollen record from the core sediments collected in the northern part of Lake Baikal represents the latest stage of the Taz (Saale) Glaciation, Kazantsevo (Eemian) Interglacial (namely the Last Interglacial), and the earliest stage of the Zyryanka (Weichselian) Glaciation. According to the palaeomagnetic-based age model applied to the core, the Last Interglacial in the Lake Baikal record lasted about 10.6 ky from 128 to 117.4 ky BP, being more or less synchronous with the Marine Isotope Stage 5e. The reconstructed changes in the south Siberian vegetation and climate are summarised as follows: a major spread of shrub alder ( Alnus fruticosa) and shrub birches ( Betula sect. Nanae/ Fruticosae) in the study area was a characteristic feature during the late glacial phase of the Taz Glaciation. Boreal trees e.g. spruce ( Picea obovata) and birch ( Betula sect. Albae) started to play an important role in the regional vegetation with the onset of the interglacial conditions. Optimal conditions for Abies sibirica- P. obovata taiga development occurred ca. 126.3 ky BP. The maximum spread of birch forest-steppe communities took place at the low altitudes ca. 126.5-125.5 ky BP and Pinus sylvestris started to form forests in the northern Baikal area after ca. 124.4 ky BP. Re-expansion of the steppe communities, as well as shrubby alder and willow communities and the disappearance of forest vegetation occurred at about 117.4 ky BP, suggesting the end of the interglacial succession. The changes in the pollen assemblages recorded in the sediments from northern Baikal point to a certain instability of the interglacial climate. Three phases of climate deterioration have been distinguished: 126-125.5, 121.5-120, and 119.5-119 ky BP. The penultimate cooling signal may be correlated with the cool oscillation recorded in European pollen records. However, such far distant correlation requires more careful investigation.

Tall shrub and tree expansion in Siberian tundra ecotones since the 1960s.

PubMed

Frost, Gerald V; Epstein, Howard E

2014-04-01

Circumpolar expansion of tall shrubs and trees into Arctic tundra is widely thought to be occurring as a result of recent climate warming, but little quantitative evidence exists for northern Siberia, which encompasses the world's largest forest-tundra ecotonal belt. We quantified changes in tall shrub and tree canopy cover in 11, widely distributed Siberian ecotonal landscapes by comparing very high-resolution photography from the Cold War-era 'Gambit' and 'Corona' satellite surveillance systems (1965-1969) with modern imagery. We also analyzed within-landscape patterns of vegetation change to evaluate the susceptibility of different landscape components to tall shrub and tree increase. The total cover of tall shrubs and trees increased in nine of 11 ecotones. In northwest Siberia, alder (Alnus) shrubland cover increased 5.3-25.9% in five ecotones. In Taymyr and Yakutia, larch (Larix) cover increased 3.0-6.7% within three ecotones, but declined 16.8% at a fourth ecotone due to thaw of ice-rich permafrost. In Chukotka, the total cover of alder and dwarf pine (Pinus) increased 6.1% within one ecotone and was little changed at a second ecotone. Within most landscapes, shrub and tree increase was linked to specific geomorphic settings, especially those with active disturbance regimes such as permafrost patterned-ground, floodplains, and colluvial hillslopes. Mean summer temperatures increased at most ecotones since the mid-1960s, but rates of shrub and tree canopy cover expansion were not strongly correlated with temperature trends and were better correlated with mean annual precipitation. We conclude that shrub and tree cover is increasing in tundra ecotones across most of northern Siberia, but rates of increase vary widely regionally and at the landscape scale. Our results indicate that extensive changes can occur within decades in moist, shrub-dominated ecotones, as in northwest Siberia, while changes are likely to occur much more slowly in the highly continental

Novel N-allyl/propargyl tetrahydroquinolines: Synthesis via Three-component Cationic Imino Diels-Alder Reaction, Binding Prediction, and Evaluation as Cholinesterase Inhibitors.

PubMed

Rodríguez, Yeray A; Gutiérrez, Margarita; Ramírez, David; Alzate-Morales, Jans; Bernal, Cristian C; Güiza, Fausto M; Romero Bohórquez, Arnold R

2016-10-01

New N-allyl/propargyl 4-substituted 1,2,3,4-tetrahydroquinolines derivatives were efficiently synthesized using acid-catalyzed three components cationic imino Diels-Alder reaction (70-95%). All compounds were tested in vitro as dual acetylcholinesterase and butyryl-cholinesterase inhibitors and their potential binding modes, and affinity, were predicted by molecular docking and binding free energy calculations (∆G) respectively. The compound 4af (IC50 = 72 μm) presented the most effective inhibition against acetylcholinesterase despite its poor selectivity (SI = 2), while the best inhibitory activity on butyryl-cholinesterase was exhibited by compound 4ae (IC50 = 25.58 μm) with considerable selectivity (SI = 0.15). Molecular docking studies indicated that the most active compounds fit in the reported acetylcholinesterase and butyryl-cholinesterase active sites. Moreover, our computational data indicated a high correlation between the calculated ∆G and the experimental activity values in both targets. © 2016 The Authors Chemical Biology & Drug Design Published by John Wiley & Sons Ltd.

Intramolecular inverse-electron-demand Diels-Alder reactions of imidazoles with 1,2,4-triazines: a new route to 1,2,3,4-tetrahydro-1,5-naphthyridines and related heterocycles.

PubMed

Lahue, Brian R; Lo, Sie-Mun; Wan, Zhao-Kui; Woo, Grace H C; Snyder, John K

2004-10-15

The intramolecular inverse-electron-demand Diels-Alder reaction between imidazoles and 1,2,4-triazines linked by a trimethylene tether from the imidazole N1 position to the triazine C3 proceed in excellent yields to produce 1,2,3,4-tetrahydro-1,5-naphthyridines. The reaction proceeds by a cycloaddition with subsequent loss of nitrogen, followed by a presumed stepwise loss of a nitrile. The analogous intramolecular cycloadditions employing a tetramethylene tether also proceeded to give 2,3,4,5-tetrahydro-1H-pyrido[3,2-b]azepines in acceptable yields. The reaction to produce the tetrahydro-1,5-naphthyridines can also be promoted with microwave irradiation.

Molecular Engineering of Perylene Imides for High-Performance Lithium Batteries: Diels-Alder Extension and Chiral Dimerization.

PubMed

Li, Lei; Hong, Yu-Jian; Chen, Dong-Yang; Lin, Mei-Jin

2017-11-21

The search for high-performance electrode materials in organic rechargeable batteries remains a key challenge. Reported herein is a molecular structural modification of perylene imides, a promising class of redox-active electrode materials, for improved battery performance. The Diels-Alder extension of perylene imides at the lateral position led to the simultaneous incorporation of two electron-withdrawing carbonyl groups and extension of the π system, which is supposed to favor high specific capacity, operating voltage, and electronic conductivity. After the chiral dimerization of the extended species with 1,2-diaminocyclohexane, it was anticipated that the porosity and coulombic interactions with lithium ions would be promoted, which would be beneficial for fast reaction kinetics and long cycling life. As expected, in lithium batteries, the obtained chiral and π-extended tweezer, which features six imide groups and a porous solid-state network of 42.2 % accessible cell volume, was found to deliver a reversible capacity of 92.1 mA h g -1 at a charge/discharge rate of 1 C within an operating voltage window of 1.60-2.80 V versus Li + /Li, around 75 and 50 % of which was maintained after 100 and 300 galvanostatic cycles, respectively, much better than those of unmodified species. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nitrogen isotope fractionation during N uptake via arbuscular mycorrhizal and ectomycorrhizal fungi into grey alder.

PubMed

Schweiger, Peter F

2016-10-20

Arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi affect plant nitrogen (N) dynamics. Plant N isotope patterns have been used to characterise the contribution of ECM fungi to plant N uptake. By quantifying and comparing the effects of an AM and an ECM fungus on growth, N uptake and isotopic composition of one host plant grown at different relative N supply levels, the aim of this study was to improve the mechanistic understanding of natural 15 N abundance patterns in mycorrhizal plants and their underlying causes. Grey alders were inoculated with one ECM fungus or one AM fungus or left non-mycorrhizal. Plants were grown under semi-hydroponic conditions and were supplied with three rates of relative N supply ranging from deficient to luxurious. Neither mycorrhizal fungus increased plant growth or N uptake. AM root colonisation had no effect on whole plant δ 15 N and decreased foliar δ 15 N only under N deficiency. The roots of these plants were 15 N-enriched. ECM root colonisation consistently decreased foliar and whole plant δ 15 N. It is concluded, that both mycorrhizal fungi contributed to plant N uptake into the shoot. Nitrogen isotope fractionation during N assimilation and transformations in fungal mycelia is suggested to have resulted in plants receiving 15 N-depleted N via the mycorrhizal uptake pathways. Negative mycorrhizal growth effects are explained by symbiotic resource trade on carbon and N and decreased direct plant N uptake. Copyright © 2016 Elsevier GmbH. All rights reserved.

Rapid synthesis of carbohydrate derivatives, including mimetics of C-linked disaccharides and C-linked aza disaccharides, using the hetero-Diels-Alder reaction.

PubMed

Burland, Peter A; Coisson, David; Osborn, Helen M I

2010-11-05

In this work we demonstrate the value of performing a hetero-Diels-Alder reaction (HDAR) between Danishefsky's diene and a range of aldehydes or imines, under microwave irradiation. By using a range of aldehydes and imines, including those derived from carbohydrates, access to functionalized 2,3-dihydro-4H-pyran-4-ones or 2,3-dihydro-4-pyridinones in good to excellent synthetic yields is possible. A particular strength of the methodology is its ability to access mimetics of C-linked disaccharides and C-linked aza disaccharides, targets of current therapeutic interest, in a rapid, convenient, and diastereoselective manner. The effect of high pressure on the HDARs involving carbohydrate-derived aldehydes and imines is also explored, with enhancement in yields occurring for the aldehyde substrates. Finally, HDARs using carbohydrate derived ketones, enones, and enals are described under a range of conditions. Optimum results were obtained under high-pressure conditions, with highly functionalized carbohydrate derivatives being afforded, in good yields, in this way.

Nesting biology of Lesser Canada Geese, Branta canadensis parvipes, along the Tanana River, Alaska

USGS Publications Warehouse

Ely, Craig R.; Pearce, J.M.; Ruess, Roger W.

2008-01-01

Lesser Canada Geese (Branta canadensis parvipes) are widespread throughout interior regions of Alaska and Canada, yet there have been no published studies documenting basic aspects of their nesting biology. We conducted a study to determine reproductive parameters of Lesser Canada Geese nesting along the Tanana River near the city of Fairbanks, in interior Alaska. Fieldwork was conducted in May of 2003, and consisted of locating nests along the riparian corridor between Fairbanks and Northpole, Alaska. Nests were found on gravel islands and shore habitats along the Tanana River, and were most commonly observed among driftwood logs associated with patches of alder (Alnus spp.) and willow (Salix spp.). Peak of nest initiation was 3-8 May, with a range from 27 April to 20 May; renesting was likely. Clutches ranged in size from 2 to 7 eggs and averaged 4.6 eggs. There was a negative correlation between clutch size and date of nest initiation. Egg size (mean mass = 128 g) was similar to other medium-sized Canada Geese. A positive correlation between egg size and clutch size was likely related to female age. Nineteen of 28 nests (68%) were active when visited; nests located on islands with nesting Mew Gulls (Larus canus) were more likely to be active than nests located elsewhere. Evidence at nest sites implicated Bald Eagles (Haliaeetus leucocephalus) and Red Foxes (Vulpes vulpes) as nest predators.

The relationship between productivities of salmonids and forest stands in northern California watersheds

USGS Publications Warehouse

Frazey, S.L.; Wilzbach, M.A.

2007-01-01

Productivities of resident salmonids and upland and riporian forests in 22 small watersheds of coastal northern California were estimated and compared to determine whether: 1) upland site productivity predicted riparian site productivity; 2) either upland or riparian site productivity predicted salmonid productivity; and 3) other parameters explained more of the variance in salmonid productivity. Upland and riparian site productivities were estimated using Site Index values for redwood (Sequoia sempervirens) and red alder (Alnus rubra), respectively. Salmonid productivity was indexed by back-calculated length at age 1 of the largest individuals sampled and by total biomass. Upland and riparian site indices were correlated, but neither factor contributed to the best approximating models of salmonid productivity. Total salmonid biomass was best described by a positive relationship with drainage area. Length of dominant fish was best described by a positive relationship with percentage of hardwoods within riparian areas, which may result from nutrient and/or litter subsidies provided by red older. The inability of forest productivity to predict salmon productivity may reflect insufficient variation in independent variables, limitations of the indices, and the operation of other factors affecting salmonid production. The lack of an apparent relationship between upland conifer and salmonid productivity suggests that management of land for timber productivity and component streams for salmonid production in these sites will require separate, albeit integrated, management strategies.

Headwater streams and forest management: does ecoregional context influence logging effects on benthic communities?

USGS Publications Warehouse

Medhurst, R. Bruce; Wipfli, Mark S.; Binckley, Chris; Polivka, Karl; Hessburg, Paul F.; Salter, R. Brion

2010-01-01

Effects of forest management on stream communities have been widely documented, but the role that climate plays in the disturbance outcomes is not understood. In order to determine whether the effect of disturbance from forest management on headwater stream communities varies by climate, we evaluated benthic macroinvertebrate communities in 24 headwater streams that differed in forest management (logged-roaded vs. unlogged-unroaded, hereafter logged and unlogged) within two ecological sub-regions (wet versus dry) within the eastern Cascade Range, Washington, USA. In both ecoregions, total macroinvertebrate density was highest at logged sites (P = 0.001) with gathering-collectors and shredders dominating. Total taxonomic richness and diversity did not differ between ecoregions or forest management types. Shredder densities were positively correlated with total deciduous and Sitka alder (Alnus sinuata) riparian cover. Further, differences in shredder density between logged and unlogged sites were greater in the wet ecoregion (logging × ecoregion interaction; P = 0.006) suggesting that differences in post-logging forest succession between ecoregions were responsible for differences in shredder abundance. Headwater stream benthic community structure was influenced by logging and regional differences in climate. Future development of ecoregional classification models at the subbasin scale, and use of functional metrics in addition to structural metrics, may allow for more accurate assessments of anthropogenic disturbances in mountainous regions where mosaics of localized differences in climate are common.

Hetero-Diels-Alder reactions of novel 3-triazolyl-nitrosoalkenes as an approach to functionalized 1,2,3-triazoles with antibacterial profile.

PubMed

Lopes, Susana M M; Novais, Juliana S; Costa, Dora C S; Castro, Helena C; Figueiredo, Agnes Marie S; Ferreira, Vitor F; Pinho E Melo, Teresa M V D; da Silva, Fernando de Carvalho

2018-01-01

The generation and reactivity of 3-triazolyl-nitrosoalkenes are reported for the first time. The study showed that hetero-Diels-Alder reaction of these heterodienes is an interesting synthetic strategy to functionalized 1,2,3-triazoles, including 1,2,3-triazolyl-pyrroles, 1,2,3-triazolyl-dipyrromethanes and 1,2,3-triazolyl-indoles. The evaluation of the antibacterial profile against Gram-positive and Gram-negative strains revealed the new 5,5'-diethyldipyrromethane bearing a side chain incorporating a triazole and oxime moieties. The antibacterial profile detected was within the Clinical and Laboratory Standard Institute (CLSI) range and against important Staphylococcus species including Methicillin-resistant strain (S. aureus ATCC 25923, S. epidermidis ATCC 12228 and S. simulans ATCC 27851 and MRSA). Interestingly, this new 1,2,3-triazole presented hemocompatibility and low in silico toxicity profile similar to antibiotics current in use. It also has an usual antibiofilm activity against MRSA, which reinforced its potential as a new antibacterial prototype. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Design of New Bridge-Ring Energetic Compounds Obtained by Diels-Alder Reactions of Tetranitroethylene Dienophile.

PubMed

He, Piao; Mei, Hao-Zheng; Wu, Le; Yang, Jun-Qing; Zhang, Jian-Guo; Cohen, Adva; Gozin, Michael

2018-03-29

The density functional theory method was employed to calculate three-dimensional structures for a series of novel explosophores. The design of new molecules (DA1-DA12) was based on the bridge-ring structures that could be formed via Diels-Alder (DA) reaction of selected nitrogen-rich dienes and tetranitroethylene dienophile. The feasibility of the proposed DA reactions was predicted on the basis of the molecular orbital theory. The strong interactions between the HOMO of dienes, with electron-donating groups (Diene2, Diene6, and Diene8), and the LUMO of tetranitroethylene dienophile suggested thermodynamically favorable formation of the desired DA reaction products. In addition to molecular structures of the explored DA compounds, their physicochemical and energetic properties were also calculated in detail. Due to compact bridge-ring structures, new energetic molecules have highly positive heats of formation (up to 1124.90 kJ·mol -1 ) and high densities (up to 2.04 g·cm -3 ). Also, as a result of all-right ratios of nitrogen and oxygen, most of the new compounds possess high detonation velocities (8.28-10.02 km·s -1 ) and high detonation pressures (30.87-47.83 GPa). Energetic compounds DA1, DA4, and DA12 exhibit a superior detonation performance over widely used HMX explosive, and DA5, DA7, and DA10 could be comparable to the state-of-the-art CL-20 and ONC explosives. Our proposed designs and synthetic methodology should provide a platform for the development of novel energetic materials with superior performance.

Characterization of Sulfonated Diels-Alder Poly(phenylene) Membranes for Electrolyte Separators in Vanadium Redox Flow Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Zhijiang; Lawton, Jamie S.; Sun, Che-Nan

2014-09-03

Here, sulfonated Diels-Alder poly(phenylene) (SDAPP) membranes were synthesized and characterized as potential electrolyte separators for vanadium redox flow batteries. The SDAPP membranes studied had ion exchange capacities of 1.4, 1.8 and 2.3 meq/g. Transmission electron microscopy imaging shows that the ionic domains in SDAPP are roughly 0.5 nm in dimension, while Nafion has a hydrophilic phase width of around 5 nm. The sulfuric acid uptake by SDAPP was higher than that for Nafion, but the materials had similar water uptake from solutions of various sulfuric acid concentrations. In equilibration with sulfuric acid concentrations ranging from 0–17.4 mol·kg -1, SDAPP withmore » a IEC of 2.3 meq/g had the highest conductivity, ranging from 0.21 to 0.05 S·cm -1, while SDAPP with a IEC of 1.8 had conductivity close to Nafion 117, ranging from 0.11 to 0.02 S·cm -1. With varying sulfuric acid concentration and temperature, vanadium permeability in SDAPP is positively correlated to the membrane's IEC. The vanadium permeability of SDAPP 2.3 is similar to that of Nafion, but permeability values for SDAPP 1.8 and SDAPP 1.4 are substantially lower. The vanadium permeation decreases with increasing electrolyte sulfuric acid concentration. Lastly, vanadium diffusion activation energy is about 20 kJ·mol -1 in both SDAPP and Nafion.« less

Gold-Catalyzed Cycloisomerization and Diels-Alder Reaction of 1,4,9-Dienyne Esters to 3 a,6-Methanoisoindole Esters with Pro-Inflammatory Cytokine Antagonist Activity.

PubMed

Susanti, Dewi; Liu, Li-Juan; Rao, Weidong; Lin, Sheng; Ma, Dik-Lung; Leung, Chung-Hang; Chan, Philip Wai Hong

2015-06-15

A synthetic method to prepare 3a,6-methanoisoindole esters efficiently by gold(I)-catalyzed tandem 1,2-acyloxy migration/Nazarov cyclization followed by Diels-Alder reaction of 1,4,9-dienyne esters is described. We also report the ability of one example to inhibit binding of tumor necrosis factor-α (TNF-α) to the tumor necrosis factor receptor 1 (TNFR1) site and TNF-α-induced nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) activation in cell at a half-maximal inhibitory concentration (IC50 ) value of 6.6 μM. Along with this is a study showing the isoindolyl derivative to exhibit low toxicity toward human hepatocellular liver carcinoma (HepG2) cells and its possible mode of activity based on molecular modeling analysis. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High performance addition-type thermoplastics (ATTs) - Evidence for the formation of a Diels-Alder adduct in the reaction of an acetylene-terminated material and a bismaleimide

NASA Technical Reports Server (NTRS)

Pater, R. H.; Soucek, M. D.; Chang, A. C.; Partos, R. D.

1991-01-01

Recently, the concept and demonstration of a new versatile synthetic reaction for making a large number of high-performance addition-type thermoplastics (ATTs) were reported. The synthesis shows promise for providing polymers having an attractive combination of easy processability, good toughness, respectable high temperature mechanical performance, and excellent thermo-oxidative stability. The new chemistry involves the reaction of an acetylene-terminated material with a bismaleimide or benzoquinone. In order to clarify the reaction mechanism, model compound studies were undertaken in solutions as well as in the solid state. The reaction products were purified by flash chromatography and characterized by conventional analytical techniques including NMR, FT-IR, UV-visible, mass spectroscopy, and high pressure liquid chromatography. The results are presented of the model compound studies which strongly support the formation of a Diels-Alder adduct in the reaction of an acetylene-terminated compound and a bismaleimide or benzoquinone.

Belowground Plant Dynamics Across an Arctic Landscape

NASA Astrophysics Data System (ADS)

Salmon, V. G.; Iversen, C. M.; Breen, A. L.; Thornton, P. E.; Wullschleger, S.

2017-12-01

High-latitude ecosystems are made up of a mosaic of different plant communities, all of which are exposed to warming at a rate double that observed in ecosystems at lower latitudes. Arctic regions are an important component of global Earth system models due to the large amounts of soil carbon (C) currently stored in permafrost as well their potential for increased plant C sequestration under warmer conditions. Losses of C from thawing and decomposing permafrost may be offset by increased plant productivity, but plant allocation to belowground structures and acquisition of limiting nutrients remain key sources of uncertainty in these ecosystems. The relationship between belowground plant traits and environmental conditions is not well understood, nor are tradeoffs between above- and belowground plant traits. To address these knowledge gaps, we sampled above- and belowground plant tissues along the Kougarok Hillslope on the Seward Peninsula, Alaska. The vegetation communities sampled included Alder shrubland, willow birch tundra, tussock tundra, dwarf shrub lichen tundra, and non-acidic mountain complex. Within each plant community, aboveground biomass was quantified and specific leaf area, leaf chemistry (%C, %N, %P and δ15N), and wood density were measured. Belowground fine-root biomass and rooting depth distribution were also determined at the community level. Fine roots from shrubs and graminoids were separated so that specific root area, diameter, and chemistry (%C, %N, %P and δ15N) could be assessed for these contrasting plant functional types. Initial findings indicate fine root biomass pools across the widely varying plant communities are constrained by soil depth, regardless of whether the rooting zone is restricted by permafrost or rock. The presence of Alnus viridis subspp. fruticosa, a deciduous shrub that facilitates nitrogen (N) fixation within its root nodules by Frankia bacteria, in Alder shrubland and willow birch tundra communities was associated

Thermal phenomena under microwave field in the organic synthesis processes: Application to the Diels Alder reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saillard, R.; Poux, M.; Audhuy-Peaudecerf, M.

1996-12-31

The influence of the microwave heating on chemical reactions were investigated. The kinetic of the Diels Alder reaction were studied under microwave irradiation at a frequency of 2.45 GHz in a single mode cavity and were compared to the kinetic obtained by a conventional heating. Experiments were carried out in a liquid solvent in order to have a better control of the medium temperature measurement. In a second part, the presence of a catalytic solid phase was introduced. Some thermal fluctuations which are due to an heterogeneity of the electric field were detected in the medium. They reduce the precisionmore » of the results and cause problems of experimental reproducibility. A thermoluminescent material allow a good visualization of these phenomena. In addition, the profiles of the electric field intensity were modelled by a 2D finite elements method in the reactor in the presence of a solvent. Despite the small size of the sample and the use of a monomode cavity which both limited the heterogeneities of the medium temperature, the authors showed a great heterogeneity of the electric field intensity and as a result the heterogeneity of the temperature in their sample. In order to avoid these phenomena which induce a lack of reproducibility, a stirring device was developed. The values of the kinetics obtained under the 2 heating modes with the introduction of the stirring device. So, it induces a good control of the medium temperature. All those investigations prompted the authors to the conclusion that there is no difference between microwave heating and a classical heating in the studied reaction.« less

Paleoclimatological analysis of Late Eocene core, Manning Formation, Brazos County, Texas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yancey, T.; Elsik, W.

1994-09-01

A core of the basal part of the Manning Formation was drilled to provide a baseline for paleoclimate analysis of the expanded section of siliciclastic sediments of late Eocene age in the outcrop belt. The interdeltaic Jackson Stage deposits of this area include 20+ cyclic units containing both lignite and shallow marine sediments. Depositional environments can be determined with precision and the repetitive nature of cycles allows comparisons of the same environment throughout, effectively removing depositional environment as a variable in interpretation of climate signal. Underlying Yegua strata contain similar cycles, providing 35+ equivalent environmental transacts within a 6 m.y.more » time interval of Jackson and Yegua section, when additional cores are taken. The core is from a cycle deposited during maximum flooding of the Jackson Stage, with deposits ranging from shoreface (carbonaceous) to midshelf, beyond the range of storm sand deposition. Sediments are leached of carbonate, but contain foram test linings, agglutinated forams, fish debris, and rich assemblages of terrestrial and marine palynomorphs. All samples examined contain marine dinoflagellates, which are most abundant in transgressive and maximum flood zones, along with agglutinated forams and fish debris. This same interval contains two separate pulses of reworked palynomorphs. The transgressive interval contains Glaphyrocysta intricata, normally present in Yegua sediments. Pollen indicates fluctuating subtropical to tropical paleoclimates, with three short cycles of cooler temperatures, indicated by abundance peaks of alder pollen (Alnus) in transgressive, maximum flood, and highstand deposits.« less

Take me to your leader: does early successional nonhost vegetation spatially inhibit Pissodes strobi (Coleoptera: Curculionidae)?

PubMed

Koopmans, Jordan M; De La Giroday, Honey-Marie C; Lindgren, B Staffan; Aukema, Brian H

2009-08-01

The spatial influences of host and nonhost trees and shrubs on the colonization patterns of white pine weevil Pissodes strobi (Peck) were studied within a stand of planted interior hybrid spruce [Picea glauca (Moench) Voss x Picea engelmannii (Parry) ex Engelm.]. Planted spruce accounted for one third of all trees within the stand, whereas the remaining two thirds were comprised of early-successional nonhost vegetation, such as alder (Alnus spp.), paper birch (Betula papyrifera Marsh.), black cottonwood [Populus balsamifera ssp. trichocarpa (T. Ng.) Brayshaw], lodgepole pine [Pinus contorta (Dougl.) ex Loud.], trembling aspen (Populus tremuloides Michx), willow (Salix spp.), and Canadian buffaloberry [Shepherdia canadensis (L.) Nutt.]. Unlike the spruce trees, nonhost vegetation in the stand was not uniformly distributed. Spatial point process models showed that Canadian buffaloberry, paper birch, black cottonwoood, and trembling aspen had negative associations with damage caused by the weevil, even though the density of the insects' hosts in these areas did not change. Moreover, knowing the locations of these nonhost trees provided as much, or more, inference about the locations of weevil-attacked trees as knowing the locations of suitable or preferred host trees (i.e., those larger in size). Nonhost volatiles, the alteration of soil composition, and overstory shade are discussed as potential explanatory factors for the patterns observed. New research avenues are suggested to determine whether nonhost vegetation in early successional stands might be an additional tool in the management of these insects in commercially important forests.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Settle, Amy E.; Berstis, Laura; Rorrer, Nicholas A.

In this tutorial review, we provide an overview of heterogeneous Diels–Alder catalysis for the production of lignocellulosic biomass-derived aromatic compounds. Diels–Alder reactions afford an extremely selective and efficient route for carbon–carbon cycloadditions to produce intermediates that can readily undergo subsequent dehydration or dehydrogenation reactions for aromatization. As a result, catalysis of Diels–Alder reactions with biomass-derived dienes and dienophiles has seen a growth of interest in recent years; however, significant opportunities remain to (i) tailor heterogeneous catalyst materials for tandem Diels–Alder and aromatization reactions, and (ii) utilize biomass-derived dienes and dienophiles to access both conventional and novel aromatic monomers. As such,more » this review discusses the mechanistic aspects of Diels–Alder reactions from both an experimental and computational perspective, as well as the synergy of Brønsted–Lewis acid catalysts to facilitate tandem Diels–Alder and aromatization reactions. Heterogeneous catalyst design strategies for Diels–Alder reactions are reviewed for two exemplary solid acid catalysts, zeolites and polyoxometalates, and recent efforts for targeting direct replacement aromatic monomers from biomass are summarized. In conclusion, we point out important research directions for progressing Diels–Alder catalysis to target novel, aromatic monomers with chemical functionality that enables new properties compared to monomers that are readily accessible from petroleum.« less

Stable-Isotope Perspectives on Holocene Environmental Change at Archaeological Sites in the Middle Tanana Valley, Interior Alaska

NASA Astrophysics Data System (ADS)

Johnson, W. C.; Gaines, E. P.

2010-12-01

Summer of 2009, Colorado State University Center for Environmental Management of Military Lands conducted test excavations of 29 prehistoric archaeological sites situated on a loess-mantled morainal ridge complex within the Jarvis Creek valley of the Tanana River system at Fort Wainwright in Interior Alaska. Initial loess deposition on the moraines began about 13,000 cal yr BP, with subsequent long-term, nomadic occupation of the area occurring from 9,500 to 1,060 cal yr BP. An array of data were extracted from bulk-sediment samples and used to assess past environmental conditions. Parameters and approaches used to generate these data included stable carbon isotope ratios, magnetic susceptibility, biogenic opal analysis, detrital charcoal content, quantitative color (L*a*b), and particle-size distribution. Stable carbon isotope trends, in combination with the other environmental proxy data, document major environmental changes. Data from the glacial till-loess transition and lower silt mantle indicate that the area was cold and slightly mesic, and dominated by treeless C3-dominated grassland immediately after the terminal Pleistocene glacial retreat (~12,700 cal yr BP). A dearth of particulate charcoal and charred phytoliths from sediments of this period suggests a minor role for fire, e.g., only localized, small fires. Cold, treeless environmental conditions continued throughout the Early Holocene (~12,000-7,000 cal yr BP), though it was more mesic than earlier. Middle Holocene (~7000-5000 cal yr BP) data display a shift in C3 grass species (increased δ13C values), the appearance of a shrub component to the plant community, significant surface stability, and more widespread fire occurrence. Picea glauca (white spruce) and Alnus sp. (alder) appear in the later parts of the Middle Holocene, and charcoal concentration increases. The Late Holocene (since ~5,000 cal yr BP) witnessed a decline in P. glauca by about 50%, a tenfold increase in Alnus, and the appearance

Synthesis and Antifungal in Vitro Evaluation of Pyrazolo[3,4-b]pyridines Derivatives Obtained by Aza-Diels-Alder Reaction and Microwave Irradiation.

PubMed

Quiroga, Jairo; Villarreal, Yazmín; Gálvez, Jaime; Ortíz, Alejandro; Insuasty, Braulio; Abonia, Rodrigo; Raimondi, Marcela; Zacchino, Susana

2017-02-01

A series of pyrazolo[3,4-b]pyridines were prepared by a microwave-assisted aza-Diels-Alder reaction between pyrazolylformimidamides 1 and β-nitrostyrenes 2 in toluene as the solvent. This procedure provides a simple one-step and environmentally friendly methodology with good yields for the synthesis of these compounds. All compounds were tested for antifungal activity against two clinically important fungi Candida albicans and Cryptococcus neoformans. Within the compounds of the series bearing a -CH 3 group on the carbon C-3 of the azole ring (3a-e), the compound without a substituent on the p'-phenyl ring (3a), showed the best activity against both fungi, followed by the p'-Br-phenyl (3c). Within the compounds of the series bearing a tert-butyl group in the carbon C-3 of the azole ring (3f-j), the non-substituted p'-compound (3f) was the most active one, followed by (3h) (p'-Br substituted) that showed the best activity against both fungi. The remaining compounds of this sub-series (3g, i, j) showed similar moderate activities. The antifungal activity of the compounds of the series was found to be correlated with a higher log P and a lower dipole moment in the more active compounds.

Inorganic ion composition in Tardigrada: cryptobionts contain a large fraction of unidentified organic solutes.

PubMed

Halberg, Kenneth Agerlin; Larsen, Kristine Wulff; Jørgensen, Aslak; Ramløv, Hans; Møbjerg, Nadja

2013-04-01

Many species of tardigrades are known to tolerate extreme environmental stress, yet detailed knowledge of the mechanisms underlying the remarkable adaptations of tardigrades is still lacking, as are answers to many questions regarding their basic biology. Here, we present data on the inorganic ion composition and total osmotic concentration of five different species of tardigrades (Echiniscus testudo, Milnesium tardigradum, Richtersius coronifer, Macrobiotus cf. hufelandi and Halobiotus crispae) using high-performance liquid chromatography and nanoliter osmometry. Quantification of the ionic content indicates that Na(+) and Cl(-) are the principal inorganic ions in tardigrade fluids, albeit other ions, i.e. K(+), NH4(+), Ca(2+), Mg(2+), F(-), SO4(2-) and PO4(3-) were also detected. In limno-terrestrial tardigrades, the respective ions are concentrated by a large factor compared with that of the external medium (Na(+), ×70-800; K(+), ×20-90; Ca(2+) and Mg(2+), ×30-200; F(-), ×160-1040, Cl(-), ×20-50; PO4(3-), ×700-2800; SO4(2-), ×30-150). In contrast, in the marine species H. crispae, Na(+), Cl(-) and SO4(2-) are almost in ionic equilibrium with (brackish) salt water, while K(+), Ca(2+), Mg(2+) and F(-) are only slightly concentrated (×2-10). An anion deficit of ~120 mEq l(-1) in M. tardigradum and H. crispae indicates the presence of unidentified ionic components in these species. Body fluid osmolality ranges from 361±49 mOsm kg(-1) in R. coronifer to 961±43 mOsm kg(-1) in H. crispae. Concentrations of most inorganic ions are largely identical between active and dehydrated groups of R. coronifer, suggesting that this tardigrade does not lose large quantities of inorganic ions during dehydration. The large osmotic and ionic gradients maintained by both limno-terrestrial and marine species are indicative of a powerful ion-retentive mechanism in Tardigrada. Moreover, our data indicate that cryptobiotic tardigrades contain a large fraction of unidentified

Intramolecular Diels-Alder Reaction of N-Alkyl-2-cyano-1-azadienes: A Study of the Eschenmoser Cycloreversion of Dihydrooxazines as a Route to N-Alkyl-2-cyano-1-azadienes.

PubMed

Motorina, Irina A.; Fowler, Frank W.; Grierson, David S.

1997-04-04

In connection with the development of the intramolecular Diels-Alder reaction (IMDA) of 1-azadienes, the 5,6-dihydro-4H-1,2-oxazine 12has been evaluated as a synthon equivalent of the 2-cyano-1-azadiene system. It was found that the dihydrooxazonium salt 27, generated in situ from the cyclic hydroxamic acid derivative 26, is converted directly to azadiene 4a via tautomerization to the corresponding enamine and a particularly facile Eschenmoser type cycloreversion process. Conditions were subsequently found for the preparation of synthon 12. N-Alkylation of this intermediate with alkyl bromides in the presence of Ag(+) ion also resulted in direct formation of the 2-cyano-1-azadiene products 38a-dand 4a. Microwave irradiation of a benzene solution of azadiene 4a proved to be a convenient means to effect its IMDA conversion to indolizidine 5a. To avoid decomposition of azadiene 38c, its intramolecular cycloaddition giving 40 (60%) was achieved by flash vacuum thermolysis.

Cytotoxicity of plants used in traditional medicine in Yemen.

PubMed

Al-Fatimi, M; Friedrich, U; Jenett-Siems, K

2005-06-01

Twenty-five extracts obtained from 14 plant species used in the traditional medicine in Yemen have been screened for cytotoxic activity against human ECV-304 cells. Extracts of Dracaena cinnabari, Eucalyptus camaldulensis, Euclea divinorum, Euphorbia cactus, Pulicaria crispa, and Withania somnifera displayed a remarkable activity.

Comparison of Five Woody Species for Reclamation of an Upper Coastal Plain Spoil Bank

Treesearch

J.W. McMinn; R.R. Roth; C.R. Berry; W.H. McNab

1980-01-01

Third-year survival and height are compared for autumn olive. European black alder, flowering crab apple, sawtooth oak, and Virginia pine on a sandy clay loam spoil bank in South Carolina. Flowering crab apple and sawtooth oak exhibited the best survival, while autumn olive and European black alder had greater height growth. Only European black alder failed to become...

UV-irradiation and leaching in water reduce the toxicity of imidacloprid-contaminated leaves to the aquatic leaf-shredding amphipod Gammarus fossarum.

PubMed

Englert, Dominic; Zubrod, Jochen P; Neubauer, Christoph; Schulz, Ralf; Bundschuh, Mirco

2018-05-01

Systemic neonicotinoid insecticides such as imidacloprid are increasingly applied against insect pest infestations on forest trees. However, leaves falling from treated trees may reach nearby surface waters and potentially represent a neonicotinoid exposure source for aquatic invertebrates. Given imidacloprid's susceptibility towards photolysis and high water solubility, it was hypothesized that the leaves' toxicity might be modulated by UV-irradiation during decay on the forest floor, or by leaching and re-mobilization of the insecticide from leaves within the aquatic ecosystem. To test these hypotheses, the amphipod shredder Gammarus fossarum was fed (over 7 d; n = 30) with imidacloprid-contaminated black alder (Alnus glutinosa) leaves that had either been pre-treated (i.e., leached) in water for up to 7 d or UV-irradiated for 1 d (at intensities relevant during autumn in Central Europe) followed by a leaching duration of 1 d. Gammarids' feeding rate, serving as sublethal response variable, was reduced by up to 80% when consuming non-pretreated imidacloprid-contaminated leaves compared to imidacloprid-free leaves. Moreover, both leaching of imidacloprid from leaves (for 7 d) as well as UV-irradiation reduced the leaves' imidacloprid load (by 46 and 90%) thereby mitigating the effects on gammarids' feeding rate to levels comparable to the respective imidacloprid-free controls. Therefore, natural processes, such as UV-irradiation and re-mobilization of foliar insecticide residues in water, might be considered when evaluating the risks systemic insecticide applications in forests might pose for aquatic organisms in nearby streams. Copyright © 2018 Elsevier Ltd. All rights reserved.

Plant Responses to Climate Change: The Case Study of Betulaceae and Poaceae Pollen Seasons (Northern Italy, Vignola, Emilia-Romagna)

PubMed Central

Mercuri, Anna Maria; Torri, Paola; Fornaciari, Rita; Florenzano, Assunta

2016-01-01

Aerobiological data have especially demonstrated that there is correlation between climate warming and the pollination season of plants. This paper focuses on airborne pollen monitoring of Betulaceae and Poaceae, two of the main plant groups with anemophilous pollen and allergenic proprieties in Northern Italy. The aim is to investigate plant responses to temperature variations by considering long-term pollen series. The 15-year aerobiological analysis is reported from the monitoring station of Vignola (located near Modena, in the Emilia-Romagna region) that had operated in the years 1990–2004 with a Hirst spore trap. The Yearly Pollen Index calculated for these two botanical families has shown contrasting trends in pollen production and release. These trends were well identifiable but fairly variable, depending on both meteorological variables and anthropogenic causes. Based on recent reference literature, we considered that some oscillations in pollen concentration could have been a main effect of temperature variability reflecting global warming. The duration of pollen seasons of Betulaceae and Poaceae, depending on the different species included in each family, has not unequivocally been determined. Phenological responses were particularly evident in Alnus and especially in Corylus as a general moving up of the end of pollination. The study shows that these trees can be affected by global warming more than other, more tolerant, plants. The research can be a contribution to the understanding of phenological plant responses to climate change and suggests that alder and hazelnut trees have to be taken into high consideration as sensible markers of plant responses to climate change. PMID:27929423

Plant Responses to Climate Change: The Case Study of Betulaceae and Poaceae Pollen Seasons (Northern Italy, Vignola, Emilia-Romagna).

PubMed

Mercuri, Anna Maria; Torri, Paola; Fornaciari, Rita; Florenzano, Assunta

2016-12-06

Aerobiological data have especially demonstrated that there is correlation between climate warming and the pollination season of plants. This paper focuses on airborne pollen monitoring of Betulaceae and Poaceae, two of the main plant groups with anemophilous pollen and allergenic proprieties in Northern Italy. The aim is to investigate plant responses to temperature variations by considering long-term pollen series. The 15-year aerobiological analysis is reported from the monitoring station of Vignola (located near Modena, in the Emilia-Romagna region) that had operated in the years 1990-2004 with a Hirst spore trap. The Yearly Pollen Index calculated for these two botanical families has shown contrasting trends in pollen production and release. These trends were well identifiable but fairly variable, depending on both meteorological variables and anthropogenic causes. Based on recent reference literature, we considered that some oscillations in pollen concentration could have been a main effect of temperature variability reflecting global warming. The duration of pollen seasons of Betulaceae and Poaceae, depending on the different species included in each family, has not unequivocally been determined. Phenological responses were particularly evident in Alnus and especially in Corylus as a general moving up of the end of pollination. The study shows that these trees can be affected by global warming more than other, more tolerant, plants. The research can be a contribution to the understanding of phenological plant responses to climate change and suggests that alder and hazelnut trees have to be taken into high consideration as sensible markers of plant responses to climate change.

Monitoring plant tissue nitrogen isotopes to assess nearshore inputs of nitrogen to Lake Crescent, Olympic National Park, Washington

USGS Publications Warehouse

Cox, Stephen E.; Moran, Patrick W.; Huffman, Raegan L.; Fradkin, Steven C.

2016-05-31

Mats of filamentous-periphytic algae present in some nearshore areas of Lake Crescent, Olympic National Park, Washington, may indicate early stages of eutrophication from nutrient enrichment of an otherwise highly oligotrophic lake. Natural abundance ratios of stable isotopes of nitrogen (δ15N) measured in plant tissue growing in nearshore areas of the lake indicate that the major source of nitrogen used by these primary producing plants is derived mainly from atmospherically fixed nitrogen in an undeveloped forested ecosystem. Exceptions to this pattern occurred in the Barnes Point area where elevated δ15N ratios indicate that effluent from septic systems also contribute nitrogen to filamentous-periphytic algae growing in the littoral zone of that area. Near the Lyre River outlet of Lake Crescent, the δ15N of filamentous-periphytic algae growing in close proximity to the spawning areas of a unique species of trout show little evidence of elevated δ15N indicating that nitrogen from on-site septic systems is not a substantial source of nitrogen for these plants. The δ15N data corroborate estimates that nitrogen input to Lake Crescent from septic sources is comparatively small relative to input from motor vehicle exhaust and vegetative sources in undeveloped forests, including litterfall, pollen, and symbiotic nitrogen fixation. The seasonal timing of blooms of filamentous-periphytic algal near the lake shoreline is also consistent with nitrogen exported from stands of red alder trees (Alnus rubra). Isotope biomonitoring of filamentous-periphytic algae may be an effective approach to monitoring the littoral zone for nutrient input to Lake Crescent from septic sources.

Cascading effects of induced terrestrial plant defences on aquatic and terrestrial ecosystem function

PubMed Central

Jackrel, Sara L.; Wootton, J. Timothy

2015-01-01

Herbivores induce plants to undergo diverse processes that minimize costs to the plant, such as producing defences to deter herbivory or reallocating limited resources to inaccessible portions of the plant. Yet most plant tissue is consumed by decomposers, not herbivores, and these defensive processes aimed to deter herbivores may alter plant tissue even after detachment from the plant. All consumers value nutrients, but plants also require these nutrients for primary functions and defensive processes. We experimentally simulated herbivory with and without nutrient additions on red alder (Alnus rubra), which supplies the majority of leaf litter for many rivers in western North America. Simulated herbivory induced a defence response with cascading effects: terrestrial herbivores and aquatic decomposers fed less on leaves from stressed trees. This effect was context dependent: leaves from fertilized-only trees decomposed most rapidly while leaves from fertilized trees receiving the herbivory treatment decomposed least, suggesting plants funnelled a nutritionally valuable resource into enhanced defence. One component of the defence response was a decrease in leaf nitrogen leading to elevated carbon : nitrogen. Aquatic decomposers prefer leaves naturally low in C : N and this altered nutrient profile largely explains the lower rate of aquatic decomposition. Furthermore, terrestrial soil decomposers were unaffected by either treatment but did show a preference for local and nitrogen-rich leaves. Our study illustrates the ecological implications of terrestrial herbivory and these findings demonstrate that the effects of selection caused by terrestrial herbivory in one ecosystem can indirectly shape the structure of other ecosystems through ecological fluxes across boundaries. PMID:25788602

Mechanisms of the Knoevenagel hetero Diels-Alder sequence in multicomponent reactions to dihydropyrans: experimental and theoretical investigations into the role of water.

PubMed

Frapper, Gilles; Bachmann, Christian; Gu, Yanlong; Coval De Sousa, Rodolphe; Jérôme, François

2011-01-14

The role of water in a multicomponent domino reaction (MCR) involving styrene, 2,4-pentanedione, and formaldehyde was studied. Whereas anhydrous conditions produced no reaction, the MCR successfully proceeded in the presence of water, affording the targeted dihydropyran derivatives with good yield. The mechanism of this MCR (Knoevenagel hetero Diels-Alder sequence) was studied with and without explicit water molecules using the SMD continuum solvation model in combination with the B3LYP density functional and the 6-311++G** basis set to compute the water and acetone (aprotic organic solvent) solution Gibbs free energies. In the Knoevenagel step, we found that water acted as a proton relay to favor the formation of more flexible six-membered ring transition state structures both in concerted (direct H(2)O elimination) and stepwise (keto-enol tautomerization and dehydration) pathways. The inclusion of a water molecule in our model resulted in a significant decrease (-8.5 kcal mol(-1)ΔG(water)(‡)) of the direct water elimination activation barrier. Owing to the presence of water, all chemical steps involved in the MCR mechanism had activation free energies barriers lower than 39 kcal mol(-1) at 25 °C in aqueous solvent (<21 kcal mol(-1) ZPE corrected electronic energies barriers). Consequently, the MCR proceeded without the assistance of any catalyst.

Soy isoflavone aglycone modulates a hematopoietic response in combination with soluble beta-glucan: SCG.

PubMed

Harada, Toshie; Masuda, Susumu; Arii, Masayuki; Adachi, Yoshiyuki; Nakajima, Mitsuhiro; Yadomae, Toshiro; Ohno, Naohito

2005-12-01

Soy isoflavone aglycones (IFAs) have a wide range of biological actions that suggest they may be of use in cancer prevention. On the other hand, a branched beta-glucan from Sparassis crispa (SCG) is a major 6-branched 1,3-beta-D-glucan in an edible/medicinal mushroom: Sparassis crispa showing antitumor activity. We have previously reported that both oral and intraperitoneal administration of SCG enhanced the hematopoietic response in cyclophosphamide (CY)-induced leukopenic mice. In this study, we investigated the hematopoietic response due to IFA in combination with SCG in CY-induced leukopenic mice. The oral administration of IFA in combination with SCG synergistically enhanced the number of white blood cells, and increased spleen weight. Analyzing the leukocyte population by flow cytometry, the combination of IFA and SCG increased the number of monocytes and granulocytes in the spleen. Taken together, the combination of IFA and SCG synergistically provides the hematopoietic responses that are enhanced over IFA or SCG alone.

Determination of ergocalciferol in human plasma after Diels-Alder derivatization by LC-MS/MS and its application to a bioequivalence study.

PubMed

Contractor, Pritesh; Gandhi, Abhishek; Solanki, Gajendra; Shah, Priyanka A; Shrivastav, Pranav S

2017-12-01

An accurate, sensitive and selective method is developed for determination of ergocalciferol (vitamin D 2 ) in human plasma using LC-MS/MS. After liquid-liquid extraction with n- hexane, ergocalciferol was derivatized by reacting with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD), a strong dienophile based on Diels-Alder reaction. Ergocalciferol and its deuterated internal standard, ergocalciferol-d6, were analyzed on X Select CSH C 18 (100 mm×4.6 mm, 2.5 µm) column using acetonitrile and 0.1% (v/v) formic acid in water containing 0.14% methylamine within 6.0 min under gradient elution mode. Tandem mass spectrometry in positive ionization mode was used to quantify ergocalciferol by multiple reaction monitoring (MRM). Entire data processing was done using Watson LIMS™ software which provided excellent data integrity and high throughput with improved operational efficiency. The major advantage of this method includes higher sensitivity (0.10 ng/mL), superior extraction efficiency (≥83%) and small sample volume (100 µL) for processing. The method was linear in the concentration range of 0.10-100 ng/mL for ergocalciferol. The intra-batch and inter-batch accuracy and precision (% CV) values varied from 97.3% to 109.0% and 1.01% to 5.16%, respectively. The method was successfully applied to support a bioequivalence study of 1.25 mg ergocalciferol capsules in 12 healthy subjects.

Genetic Selection for Improved Abzymes in E. Coli

DTIC Science & Technology

1994-08-03

immunoassay to scemen antibody phage libraries directly for catalysis of a bimolecular Diels - Alder reaction and have identified several active clones...sensitive growth selection assay in F coli for catalysts with chorismate mutase activity; and (3) we identified new abzymes for a Diels - Alder ...generated combinatorial antibody libraries from mRNA isolated from the spleens of mice hyperimmunized with transition state analogs for Diels - Alder and

N-O chemistry for antibiotics: discovery of N-alkyl-N-(pyridin-2-yl)hydroxylamine scaffolds as selective antibacterial agents using nitroso Diels-Alder and ene chemistry.

PubMed

Wencewicz, Timothy A; Yang, Baiyuan; Rudloff, James R; Oliver, Allen G; Miller, Marvin J

2011-10-13

The discovery, syntheses, and structure-activity relationships (SAR) of a new family of heterocyclic antibacterial compounds based on N-alkyl-N-(pyridin-2-yl)hydroxylamine scaffolds are described. A structurally diverse library of ∼100 heterocyclic molecules generated from Lewis acid-mediated nucleophilic ring-opening reactions with nitroso Diels-Alder cycloadducts and nitroso ene reactions with substituted alkenes was evaluated in whole cell antibacterial assays. Compounds containing the N-alkyl-N-(pyridin-2-yl)hydroxylamine structure demonstrated selective and potent antibacterial activity against the Gram-positive bacterium Micrococcus luteus ATCC 10240 (MIC(90) = 2.0 μM or 0.41 μg/mL) and moderate activity against other Gram-positive strains including antibiotic resistant strains of Staphylococcus aureus (MRSA) and Enterococcus faecalis (VRE). A new synthetic route to the active core was developed using palladium-catalyzed Buchwald-Hartwig amination reactions of N-alkyl-O-(4-methoxybenzyl)hydroxylamines with 2-halo-pyridines that facilitated SAR studies and revealed the simplest active structural fragment. This work shows the value of using a combination of diversity-oriented synthesis (DOS) and parallel synthesis for identifying new antibacterial scaffolds.

N-O Chemistry for Antibiotics: Discovery of N-Alkyl-N-(pyridin-2-yl)hydroxylamine Scaffolds as Selective Antibacterial Agents Using Nitroso Diels-Alder and Ene Chemistry

PubMed Central

Wencewicz, Timothy A.; Yang, Baiyuan; Rudloff, James R.; Oliver, Allen G.; Miller, Marvin J.

2011-01-01

The discovery, syntheses, and structure-activity relationships (SAR) of a new family of heterocyclic antibacterial compounds based on N-alkyl-N-(pyridin-2-yl)hydroxylamine scaffolds are described. A structurally diverse library of ~100 heterocyclic molecules generated from Lewis acid-mediated nucleophilic ring opening reactions with nitroso Diels-Alder cycloadducts and nitroso ene reactions with substituted alkenes was evaluated in whole cell antibacterial assays. Compounds containing the N-alkyl-N-(pyridin-2-yl)hydroxylamine structure demonstrated selective and potent antibacterial activity against the Gram-positive bacterium Micrococcus luteus ATCC 10240 (MIC90 = 2.0 μM or 0.41 μg/mL) and moderate activity against other Gram-positive strains including antibiotic resistant strains of Staphylococcus aureus (MRSA) and Enterococcus faecalis (VRE). A new synthetic route to the active core was developed using palladium-catalyzed Buchwald-Hartwig amination reactions of N-alkyl-O-(4-methoxybenzyl)hydroxylamines with 2-halo-pyridines that facilitated SAR studies and revealed the simplest active structural fragment. This work shows the value of using a combination of diversity-oriented synthesis (DOS) and parallel synthesis for identifying new antibacterial scaffolds. PMID:21859126

Short Rotation Woody Crops Program. Quarterly progress report, March 1-May 31, 1985. [Sycamore, alders, black locust, larch, poplars, saltbush

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wright, L.L.; Perlack, R.D.; Wenzel, C.R.

1985-08-01

This report covers the progress of the Short Rotation Woody Crops Program (SRWCP) during the third quarter of fiscal year 1985. This report summarizes ORNL management activities, technical activities at ORNL and subcontract institutions, and the technology transfer that is occurring as a result of subcontractor and ORNL activities. Third-year results of a nutrient utilization study confirmed that there were no benefits to quarterly fertilization with urea nitrogen. Testing of one prototype short-rotation intensive culture harvester was conducted on a sycamore plantation on Scott Paper Company land in southern Alabama. Coppice yields of European black alder reported by Iowa Statemore » University indicate potential productivity of about 7.2 dry Mg . ha/sup -1/ . year/sup -1/ if the best trees are selected. Coppice yields were more than double first-rotation yields. About 31,000 black locust and larch trees were established in 12 genetic tests at 4 sites in Michigan. Seedling rotation productivity rates of 4-year-old hybrid poplar, based on harvest data, were reported by Pennsylvania State University. Rates varied from 4.8 dry Mg . ha/sup -1/ . year/sup -1/ to 10.7 dry Mg . ha/sup -1/ . year/sup -1/, depending on site, management strategy, and planting year. An efficient method for in vitro micropropagation of elite genotypes of fourwing saltbush was developed by Plant Resources Institute. A new study to evaluate yield/density relationships was established by the USDA Forest Service, Pacific Northwest Forest and Range Experiment Station. Dissertation research on the crown geometry of plantation-grown American sycamore was completed.« less

A new class of dual responsive self-healable hydrogels based on a core crosslinked ionic block copolymer micelle prepared via RAFT polymerization and Diels-Alder "click" chemistry.

PubMed

Banerjee, Sovan Lal; Singha, Nikhil K

2017-12-06

Amphiphilic diblock copolymers of poly(furfuryl methacrylate) (PFMA) with cationic poly(2-(methacryloyloxy)ethyltrimethyl ammonium chloride) (PFMA-b-PMTAC) and anionic poly(sodium 4-vinylbenzenesulfonate) (PFMA-b-PSS) were prepared via reversible addition fragmentation chain-transfer (RAFT) polymerization by using PFMA as a macro-RAFT agent. The formation of the block copolymer was confirmed by FTIR and 1 H NMR analyses. In water, the amphiphilic diblock copolymers, (PFMA-b-PMTAC) and (PFMA-b-PSS), formed micelles with PFMA in the core and the rest of the hydrophilic polymers like PMTAC and PSS in the corona. The PFMA core was crosslinked by using Diels-Alder (DA) "Click" chemistry in water at 60 °C where bismaleimide acted as a crosslinker. Afterwards, both the core crosslinked micelles were mixed at an almost equal charge ratio which was determined by zeta potential analysis to prepare the self-assembled hydrogel. The de-crosslinking of the hydrophobic PFMA core in the self-assembled hydrogel via rDA reaction took place at 165 °C as determined from DSC analysis. This hydrogel showed self-healing behavior using ionic interaction (in the presence of water) and DA chemistry (in the presence of heat).

First evidence of epithelial transport in tardigrades: a comparative investigation of organic anion transport.

PubMed

Halberg, Kenneth Agerlin; Møbjerg, Nadja

2012-02-01

We investigated transport of the organic anion Chlorophenol Red (CPR) in the tardigrade Halobiotus crispae using a new method for quantifying non-fluorescent dyes. We compared the results acquired from the tardigrade with CPR transport data obtained from Malpighian tubules of the desert locust Schistocerca gregaria. CPR accumulated in the midgut lumen of H. crispae, indicating that organic anion transport takes place here. Our results show that CPR transport is inhibited by the mitochondrial un-coupler DNP (1 mmol l(-1); 81% reduction), the Na(+)/K(+)-ATPase inhibitor ouabain (10 mmol l(-1); 21% reduction) and the vacuolar H(+)-ATPase inhibitor bafilomycin (5 μmol l(-1); 21% reduction), and by the organic anions PAH (10 mmol l(-1); 44% reduction) and probenecid (10 mmol l(-1); 61% reduction, concentration-dependent inhibition). Transport by locust Malpighian tubules exhibits a similar pharmacological profile, albeit with markedly higher concentrations of CPR being reached in S. gregaria. Immunolocalization of the Na(+)/K(+)-ATPase α-subunit in S. gregaria revealed that this transporter is abundantly expressed and localized to the basal cell membranes. Immunolocalization data could not be obtained from H. crispae. Our results indicate that organic anion secretion by the tardigrade midgut is transporter mediated with likely candidates for the basolateral entry step being members of the Oat and/or Oatp transporter families. From our results, we cautiously suggest that apical H(+) and possibly basal Na(+)/K(+) pumps provide the driving force for the transport; the exact coupling between electrochemical gradients generated by the pumps and transport of ions, as well as the nature of the apical exit step, are unknown. This study is, to our knowledge, the first to show active epithelial transport in tardigrades.

Effects of multiple but low pesticide loads on aquatic fungal communities colonizing leaf litter.

PubMed

Talk, Anne; Kublik, Susanne; Uksa, Marie; Engel, Marion; Berghahn, Rüdiger; Welzl, Gerhard; Schloter, Michael; Mohr, Silvia

2016-08-01

In the first tier risk assessment (RA) of pesticides, risk for aquatic communities is estimated by using results from standard laboratory tests with algae, daphnids and fish for single pesticides such as herbicides, fungicides, and insecticides. However, fungi as key organisms for nutrient cycling in ecosystems as well as multiple pesticide applications are not considered in the RA. In this study, the effects of multiple low pesticide pulses using regulatory acceptable concentrations (RACs) on the dynamics of non-target aquatic fungi were investigated in a study using pond mesocosm. For that, fungi colonizing black alder (Alnus glutinosa) leaves were exposed to multiple, low pulses of 11 different pesticides over a period of 60days using a real farmer's pesticide application protocol for apple cropping. Four pond mesocosms served as treatments and 4 as controls. The composition of fungal communities colonizing the litter material was analyzed using a molecular fingerprinting approach based on the terminal Restriction Fragment Length Polymorphism (t-RFLP) of the fungal Internal Transcribed Spacer (ITS) region of the ribonucleic acid (RNA) gene(s). Our data indicated a clear fluctuation of fungal communities based on the degree of leaf litter degradation. However significant effects of the applied spraying sequence were not observed. Consequently also degradation rates of the litter material were not affected by the treatments. Our results indicate that the nutrient rich environment of the leaf litter material gave fungal communities the possibility to express genes that induce tolerance against the applied pesticides. Thus our data may not be transferred to other fresh water habitats with lower nutrient availability. Copyright © 2016. Published by Elsevier B.V.

Shrub sensitivity to recent warming across Arctic Alaska from dendrochronological and remote sensing records

NASA Astrophysics Data System (ADS)

Andreu-Hayles, Laia; Gaglioti, Benjamin V.; D'Arrigo, Rosanne; Anchukaitis, Kevin J.; Goetz, Scott

2017-04-01

Shrub expansion into Arctic and alpine tundra ecosystems has been documented during the last several decades based on repeat aerial photography, remote sensing, and ground-truthed estimates of vegetation cover. Today, summer temperatures limit the northern limit of Arctic shrubs, and warmer summers have been shown to have higher NDVI in shrub tundra zones. Although global warming has been considered the main driver of shrub expansion, soil types, shrub species and non-linear responses can moderate how sensitive shrub growth is to climate warming. Here, we assess the sensitivity of shrub growth to inter-annual climate variability using a newly generated network of 18 shrub ring-width chronologies in the tundra regions of the North Slope of Alaska. We then test whether the dendroclimatic patterns we observe at individual sites are representative of the broader region using remotely sensed productivity data (NDVI). The common period of both satellite and shrub ring data from all sites was 1982 to 2010. Instrumental daily data from Toolik Lake and interpolated products was compared to detrended growth rates of Salix spp. (willow) and Alnus sp. (alder), located on and to the west of the Dalton Highway ( 68-70°N 148°W). Whereas summer temperatures were found to enhance shrub growth, warm temperatures outside the core of the growing season have the inverse effect in some chronologies. All tundra shrub chronologies shared a common strong positive response to summer temperatures despite growing in heterogeneous site conditions and belonging to different species. In this work we will discuss shrub climate sensitive across Alaska and how NDVI data compared to the shrub ring-width network.

Effects of Recent Debris Flows on Stream Ecosystems and Food Webs in Small Watersheds in the Central Klamath Mountains, NW California

NASA Astrophysics Data System (ADS)

Cover, M. R.; de La Fuente, J.

2008-12-01

Debris flows are common erosional processes in steep mountain areas throughout the world, but little is known about the long-term ecological effects of debris flows on stream ecosystems. Based on debris flow histories that were developed for each of ten tributary basins, we classified channels as having experienced recent (1997) or older (pre-1997) debris flows. Of the streams classified as older debris flow streams, three streams experienced debris flows during floods in 1964 or 1974, while two streams showed little or no evidence of debris flow activity in the 20th century. White alder (Alnus rhombifolia) was the dominant pioneer tree species in recent debris flow streams, forming localized dense patches of canopy cover. Maximum temperatures and daily temperature ranges were significantly higher in recent debris flow streams than in older debris flow streams. Debris flows resulted in a shift in food webs from allochthonous to autochthonous energy sources. Primary productivity, as measured by oxygen change during the day, was greater in recent debris flow streams, resulting in increased abundances of grazers such as the armored caddisfly Glossosoma spp. Detritivorous stoneflies were virtually absent in recent debris flow streams because of the lack of year-round, diverse sources of leaf litter. Rainbow trout (Oncorhynchus mykiss) were abundant in four of the recent debris flow streams. Poor recolonizers, such as the Pacific giant salamander (Dicamptodon tenebrosus), coastal tailed frog (Ascaphus truei), and signal crayfish (Pacifistacus leniusculus), were virtually absent in recent debris flow streams. Forest and watershed managers should consider the role of forest disturbances, such as road networks, on debris flow frequency and intensity, and the resulting ecological effects on stream ecosystems.

Environmental drivers of spatial variation in whole-tree transpiration in an aspen-dominated upland-to-wetland forest gradient

NASA Astrophysics Data System (ADS)

Loranty, Michael M.; Mackay, D. Scott; Ewers, Brent E.; Adelman, Jonathan D.; Kruger, Eric L.

2008-02-01

Assumed representative center-of-stand measurements are typical inputs to models that scale forest transpiration to stand and regional extents. These inputs do not consider gradients in transpiration at stand boundaries or along moisture gradients and therefore potentially bias the large-scale estimates. We measured half-hourly sap flux (JS) for 173 trees in a spatially explicit cyclic sampling design across a topographically controlled gradient between a forested wetland and upland forest in northern Wisconsin. Our analyses focused on three dominant species in the site: quaking aspen (Populus tremuloides Michx), speckled alder (Alnus incana (DuRoi) Spreng), and white cedar (Thuja occidentalis L.). Sapwood area (AS) was used to scale JS to whole tree transpiration (EC). Because spatial patterns imply underlying processes, geostatistical analyses were employed to quantify patterns of spatial autocorrelation across the site. A simple Jarvis type model parameterized using a Monte Carlo sampling approach was used to simulate EC (EC-SIM). EC-SIM was compared with observed EC(EC-OBS) and found to reproduce both the temporal trends and spatial variance of canopy transpiration. EC-SIM was then used to examine spatial autocorrelation as a function of environmental drivers. We found no spatial autocorrelation in JS across the gradient from forested wetland to forested upland. EC was spatially autocorrelated and this was attributed to spatial variation in AS which suggests species spatial patterns are important for understanding spatial estimates of transpiration. However, the range of autocorrelation in EC-SIM decreased linearly with increasing vapor pressure deficit, implying that consideration of spatial variation in the sensitivity of canopy stomatal conductance to D is also key to accurately scaling up transpiration in space.

Assessing habitat selection in Spring by male American Woodcock in Maine with a geographic information system

USGS Publications Warehouse

Sprankle, K.E.; Sepik, G.F.; McAuley, D.G.; Longcore, J.R.; McAuley, Daniel G.; Bruggink, John G.; Sepik, Greg F.

2000-01-01

Geographic information system (GIS) technology was used to identify habitats available to and used by male American woodcock (Scolopax minor) equipped with radio transmitters--54 in 1987, 51 in 1988, 46 in 1989 at Moosehorn National Wildlife Refuge, Maine. Woodcock were monitored from time of capture (25 March-15 April) to 15 June each year. To determine habitat selection by male woodcock, the following habitat characteristics were measured: land cover, age and stocking density of the forest overstory, soil drainage and texture, aspect, and percent slope. Habitat selection was examined as affected by the covariates weather and age-class of woodcock, and among years for diurnal and crepuscular periods of the breeding period. Multivariate techniques that compare use and availability of habitats were not available, so a statistical model was developed to rate importance of multiple habitat characteristics selected by woodcock. The most critical period for woodcock in terms of survival was from arrival to: mid-April. Second-year and after-second-year woodcock did not select different (P > 0.05) habitat types, but they did select different types among years and within breeding intervals (P < 0.05). In years when weather was moderate, woodcock selected young, dense stands of speckled alder (Alnus rugosa) and hardwoods, interspersed with forest openings. Suitable habitat can be maintained by creating an uneven-aged forest managed in even-aged blocks composed of several hardwood species. Managers can now quantify suitable woodcock habitat in a GIS and plan large-scale forest-harvesting strategies using data on several habitat characteristics (e.g., land cover, stand age, stocking density, soil drainage and texture, and aspect).

Herbal composition Gambigyeongsinhwan (4) from Curcuma longa, Alnus japonica, and Massa Medicata Fermentata inhibits lipid accumulation in 3T3-L1 cells and regulates obesity in Otsuka Long-Evans Tokushima Fatty rats.

PubMed

Roh, Jong Sung; Lee, Hyunghee; Woo, Sangee; Yoon, Miso; Kim, Jeongjun; Park, Sun Dong; Shin, Soon Shik; Yoon, Michung

2015-08-02

Adipocyte lipid accumulation due to impaired fatty acid oxidation causes adipocyte hypertrophy and adipose tissue increment, leading to obesity. The aim of this study was to determine the antiobesity effects of the herbal composition Gambigyeongsinhwan (4) (GGH(4)) composed of Curcuma longa L. (Zingiberaceae), Alnus japonica (Thunb.) Steud. (Betulaceae), and the fermented traditional Korean medicine Massa Medicata Fermentata. The effects of GGH(4) and the individual components on lipid accumulation in 3T3-L1 adipocytes and body weight gain in Otsuka Long-Evans Tokushima Fatty (OLETF) rats were examined using Oil red O staining, hematoxylin and eosin staining, quantitative real-time PCR, and peroxisome proliferator-activated receptor α (PPARα) transactivation assay. GGH(4), individual components, and an active principle of Curcuma longa curcumin inhibited lipid accumulation and mRNA levels of adipocyte-specific genes (PPARγ, aP2, and C/EBPα) in 3T3-L1 adipocytes compared with control cells. Treatment with GGH(4), the individual components or curcmumin increased mRNA levels of mitochondrial (CPT-1, MCAD, and VLCAD) and peroxisomal (ACOX and thiolase) PPARα target genes. GGH(4) and the individual components also increased PPARα reporter gene expression compared with control cells. These effects were most prominent in GGH(4)-treated cells. However, the PPARα antagonist GW6471 reversed the inhibitory effects of GGH(4) on adipogenesis. An in vivo study showed that GGH(4) decreased body weight gain, adipose tissue mass, and visceral adipocyte size with increasing mRNA levels of adipose tissue PPARα target genes in OLETF rats. These results demonstrate that GGH(4) has an antiobesity effects through the inhibition of adipocyte lipid accumulation, and this process may be mediated in part through adipose PPARα activation. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

On the effect of tether composition on cis/trans selectivity in intramolecular Diels-Alder reactions.

PubMed

Paddon-Row, Michael N; Longshaw, Alistair I; Willis, Anthony C; Sherburn, Michael S

2009-01-05

Intramolecular Diels-Alder (IMDA) transition structures (TSs) and energies have been computed at the B3LYP/6-31+G(d) and CBS-QB3 levels of theory for a series of 1,3,8-nonatrienes, H(2)C=CH-CH=CH-CH(2)-X-Z-CH=CH(2) [-X-Z- = -CH(2)-CH(2)- (1); -O-C(=O)- (2); -CH(2)-C(=O)- (3); -O-CH(2)- (4); -NH-C(=O)- (5); -S-C(=O)- (6); -O-C(=S)- (7); -NH-C(=S)- (8); -S-C(=S)- (9)]. For each system studied (1-9), cis- and trans-TS isomers, corresponding, respectively, to endo- and exo-positioning of the -C-X-Z- tether with respect to the diene, have been located and their relative energies (E(rel) (TS)) employed to predict the cis/trans IMDA product ratio. Although the E(rel) (TS) values are modest (typically <3 kJ mol(-1)), they follow a clear and systematic trend. Specifically, as the electronegativity of the tether group X is reduced (X=O --> NH or S), the IMDA cis stereoselectivity diminishes. The predicted stereochemical reaction preferences are explained in terms of two opposing effects operating in the cis-TS, namely (1) unfavorable torsional (eclipsing) strain about the C4-C5 bond, that is caused by the -C-X-C(=Y)- group's strong tendency to maintain local planarity; and (2) attractive electrostatic and secondary orbital interactions between the endo-(thio)carbonyl group, C=Y, and the diene. The former interaction predominates when X is weakly electronegative (X=N, S), while the latter is dominant when X is more strongly electronegative (X=O), or a methylene group (X=CH(2)) which increases tether flexibility. These predictions hold up to experimental scrutiny, with synthetic IMDA reactions of 1, 2, 3, and 4 (published work) and 5, 6, and 8 (this work) delivering ratios close to those calculated. The reactions of thiolacrylate 5 and thioamide 8 represent the first examples of IMDA reactions with tethers of these types. Our results point to strategies for designing tethers, which lead to improved cis/trans-selectivities in IMDAs that are normally only weakly selective

Seasonal relationships between precipitation, forest floor, and streamwater nitrogen, Isle Royale, Michigan

USGS Publications Warehouse

Stottlemyer, R.; Toczydlowski, D.

1999-01-01

The Upper Great Lakes receive large amounts of precipitation-NH4/+ and moderate NO3/- inputs. Increased atmospheric inorganic N input has led to concern about ecosystem capacity to utilize excess N. This paper summarizes a 5-yr study of seasonal N content and flux in precipitation, snowpack, forest floor, and streamwater in order to assess the source of inorganic N outputs in streamflow from a small boreal watershed. Average precipitation N input was 3 kg ha-1 yr-1. The peak snowpack N content averaged 0.55 kg ha-1. The forest floor inorganic N pool was ???2 kg ha-1, eight times larger than monthly precipitation N input. The inorganic N pool size peaked in spring and early summer. Ninety percent of the forest floor inorganic N pool was made up of NH4/+-N. Forest floor inorganic N pools generally increased with temperature. Net N mineralization was 15 kg ha-1 yr-1, and monthly rates peaked in early summer. During winter, the mean monthly net N mineralization rate was twice the peak snowpack N content. Streamwater NO3/- concentration peaked in winter, and inorganic N output peaked in late fall. Beneath the dominant boreal forest species, net N mineralization rates were positively correlated (P < 0.05) with streamwater NO3/- concentrations. Forest floor NO3/- pools beneath alder [Alnus rugosa (Du Roi) Spreng] were positively correlated (P < 0.01) to streamwater NO3/- output. At the watershed mouth, streamwater NO3/- concentrations were positively correlated (P < 0.05) with precipitation NO3/- input and precipitation amount. The relatively small snowpack N content and seasonal precipitation N input compared to forest floor inorganic N pools and net N mineralization rates, the strong ecosystem retention of precipitation N inputs, and the seasonal streamwater NO3/- concentration and output pattern all indicated that little streamwater NO3/- came directly from precipitation or snowmelt.The Upper Great Lakes receive large amounts of precipitation-NH4+ and moderate NO3

Controls on ecohydrological dynamics of riparian zones in Alpine catchments: A comparison study of two rivers in the Eastern Italian Alps

NASA Astrophysics Data System (ADS)

Engel, Michael; Penna, Daniele; Frentress, Jay; Andreoli, Andrea; Hecher, Peter; Van Meerveld, Ilja; Comiti, Francesco

2017-04-01

In recent decades, restauration actions have been implemented in mountain rivers to face widespread morphological changes. Such natural and anthropogenic modifications can have relevant impacts on the ecological and ecohydrological functioning of riparian vegetation. Understanding the water sources used by riparian vegetation is important for the implementation of effective river restoration initiatives. Therefore, more ecohydrological research is needed to quantify the complex interactions between hydrology and vegetation in different alpine river systems. In this study we used water stable isotopes and electrical conductivity (EC) as tracers to better understand the hydrological and ecohydrological relationship between the riparian vegetation and the river bed of alpine river systems. We choose two catchments, Ahr/Aurino River and Mareit/Ridanna River catchments (South Tyrol, Italy) as study sites. In both catchments, we selected two sites comprising a younger (< 5 years) and an older (> 10 years) alder (Alnus incana) stand. At each site, soil moisture at different depths and groundwater levels were monitored. Suction lysimeters were installed at the same depths than the soil moisture sensors. Samples for tracer analysis were collected since June 2016 on a bi-weekly or monthly basis from precipitation, soil water, groundwater and stream water. EC was continuously measured in a piezometer at the Mareit River. In addition, we extracted sap water for isotopic analysis from alder trees. First results show that all water types sampled in both catchments fell along the global meteoric water line showing no evaporative enrichments. Sap samples are expected to deviate from the meteoric line but they have not been analysed yet. At both sites in the Ahr catchment, soil water seemed to be more variable and isotopically more enriched at 10 cm depth (δ2H: - 34 to -69 ‰) than at 50 cm (δ2H: -45 to -71 ‰), indicating a decreasing influence of precipitation with increasing

[Chemistry and biosynthesis of prenylflavonoids].

PubMed

Nomura, T

2001-07-01

Many isoprenylated flavonoids have been isolated from mulberry trees and related plants (Moraceae). Among them, kuwanons G (13) and H (14) were the first isolated active substances exhibiting a hypotensive effect from the Japanese Morus root bark. These compounds are considered to be formed through an enzymatic Diels-Alder reaction of a chalcone (15) and dehydro-kuwanon C (16) or its equivalent. Since that time, about forty kinds of Diels-Alder type adducts structurally similar to that of 13 have been isolated from the moraceous plants. Some strains of Morus alba as well as M. bombycis callus tissues have a high productivity of mulberry Diels-Alder type adducts, such as chalcomoracin (26) and kuwanon J (28). The biosynthesis of the mulberry Diels-Alder type adducts has been studied with the aid of the cell strain. Chalcomoracin (26) and kuwanon J (28) were proved to be enzymatic Diels-Alder type reaction products by the administration experiment with O-methylchalcone derivatives. Furthermore, for the isoprenoid biosynthesis of prenylflavonoids in Morus alba callus tissues, a novel way through the junction of glycolysis and pentose-phosphate cycle was proposed. The crude enzyme fraction catalyzing the Morus Diels-Alder type reaction could be isolated. Studies of phenolic constituents of licorice (Glycyrrhiza species) were carried out. On the course of the structure determination of the phenolic constituents of licorice, two new NMR structure determination methods for prenylflavonoids were found. Furthermore, the prenylphenols isolated from licorice were summarized according to the origin of the materials.

Chemistry and biosynthesis of isoprenylated flavonoids from Japanese mulberry tree

PubMed Central

Nomura, Taro; Hano, Yoshio; Fukai, Toshio

2009-01-01

Many isoprenylated flavonoids have been isolated from Japanese mulberry tree (Moraceae). Among them, kuwanons G (1) and H (2) were the first isolated active substances exhibiting a hypotensive effect. These compounds are considered to be formed through an enzymatic Diels-Alder type reaction between an isoprenyl portion of an isoprenylphenol as the diene and an α, β-double bond of chalcone as the dienophile. The absolute configurations of these Diels-Alder type adducts were confirmed by three different methods. The stereochemistries of the adducts were consistent with those of ones in the Diels-Alder reaction involving exo- and endo-addition. Some strains of Morus alba callus tissues have a high productivity of mulberry Diels-Alder type adducts, such as chalcomoracin (3) and kuwanon J (4). The biosynthetic studies of the mulberry Diels-Alder type adducts have been carried out with the aid of the cell strain. Chalcomoracin (3) and kuwanon J (4) were proved to be enzymatic Diels-Alder type reaction products by the administration experiments with O-methylchalcone derivatives. Furthermore, for the isoprenoid biosynthesis of prenylflavonoids in Morus alba callus tissues by administration of [1,3-13C2]- and [2-13C]-glycerol, a novel way through the junction of glycolysis and pentose-phosphate cycle was proved. Two independent isoprenoid biosynthetic pathways, that for sterols and that for isoprenoidphenols, operate in the Morus alba cell cultures. The former is susceptible to compactin (ML-236) and the latter resists to compactin in the cell cultures, respectively. PMID:19907125

Reef fishes can recognize bleached habitat during settlement: sea anemone bleaching alters anemonefish host selection.

PubMed

Scott, Anna; Dixson, Danielle L

2016-05-25

Understanding how bleaching impacts the settlement of symbiotic habitat specialists and whether there is flexibility in settlement choices with regard to habitat quality is essential given our changing climate. We used five anemonefishes (Amphiprion clarkii, Amphiprion latezonatus, Amphiprion ocellaris, Amphiprion percula and Premnas biaculeatus) and three host sea anemones (Entacmaea quadricolor, Heteractis crispa and Heteractis magnifica) in paired-choice flume experiments to determine whether habitat naive juveniles have the olfactory capabilities to distinguish between unbleached and bleached hosts, and how this may affect settlement decisions. All anemonefishes were able to distinguish between bleached and unbleached hosts, and responded only to chemical cues from species-specific host anemones irrespective of health status, indicating a lack of flexibility in host use. While bleached hosts were selected as habitat, this occurred only when unbleached options were unavailable, with the exception of A. latezonatus, which showed strong preferences for H. crispa regardless of health. This study highlights the potential deleterious indirect impacts of declining habitat quality during larval settlement in habitat specialists, which could be important in the field, given that bleaching events are becoming increasingly common. © 2016 The Author(s).

Granulocyte-macrophage colony-stimulating factor (GM-CSF) regulates cytokine induction by 1,3-beta-D-glucan SCG in DBA/2 mice in vitro.

PubMed

Harada, Toshie; Miura, Noriko N; Adachi, Yoshiyuki; Nakajima, Mitsuhiro; Yadomae, Toshiro; Ohno, Naohito

2004-08-01

Sparassis crispa Fr. is an edible/medicinal mushroom that recently became cultivable in Japan. SCG is a major 6-branched 1,3-beta-D-glucan in S. crispa showing antitumor activity. We recently found that the splenocytes from naive DBA/1 and DBA/2 mice strongly react with SCG to produce interferon-gamma (IFN-gamma). In this study, cytokines induced by SCG were screened and found to be IFN-gamma, tumor necrosis factor-alpha (TNF-alpha), granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukin-12 (IL-12p70). The addition of recombinant murine GM-CSF (rMuGM-CSF) to spleen cell cultures from various strains of mice synergistically enhanced IFN-gamma, TNF-alpha and IL-12p70 in the presence of SCG. In contrast, neutralizing GM-CSF using anti-GM-CSF monoclonal antibody (mAb) significantly inhibited IFN-gamma, TNF-alpha, and IL-12p70 elicited by SCG. We conclude that GM-CSF is a key molecule for cytokine induction by beta-glucan, and GM-CSF induction by SCG is the specific step in DBA/2 mice in vitro.

Reef fishes can recognize bleached habitat during settlement: sea anemone bleaching alters anemonefish host selection

PubMed Central

Scott, Anna; Dixson, Danielle L.

2016-01-01

Understanding how bleaching impacts the settlement of symbiotic habitat specialists and whether there is flexibility in settlement choices with regard to habitat quality is essential given our changing climate. We used five anemonefishes (Amphiprion clarkii, Amphiprion latezonatus, Amphiprion ocellaris, Amphiprion percula and Premnas biaculeatus) and three host sea anemones (Entacmaea quadricolor, Heteractis crispa and Heteractis magnifica) in paired-choice flume experiments to determine whether habitat naive juveniles have the olfactory capabilities to distinguish between unbleached and bleached hosts, and how this may affect settlement decisions. All anemonefishes were able to distinguish between bleached and unbleached hosts, and responded only to chemical cues from species-specific host anemones irrespective of health status, indicating a lack of flexibility in host use. While bleached hosts were selected as habitat, this occurred only when unbleached options were unavailable, with the exception of A. latezonatus, which showed strong preferences for H. crispa regardless of health. This study highlights the potential deleterious indirect impacts of declining habitat quality during larval settlement in habitat specialists, which could be important in the field, given that bleaching events are becoming increasingly common. PMID:27226472

ELF Communications System Ecological Monitoring Program: A Summary Report for 1982-1992

DTIC Science & Technology

1993-10-01

autumn- abscised alder leaves were used in the packs; since 1990, only fresh alder leaves have been used. Leaf packs were periodically retrieved and...red pine planting survival. Northern Journal of Applied Forestry, 5:14; 1988. 56. Connaughton, P. The effects of acid precipitation on nutrient levels

A Stratigraphic Pollen Record from a Late Pleistocene Cypress Forest, Northern Gulf of Mexico Continental Shelf

NASA Astrophysics Data System (ADS)

Reese, A.; Harley, G. L.; DeLong, K. L.; Bentley, S. J.; Xu, K.; Gonzalez Rodriguez, S. M.; Truong, J. T.; Obelcz, J.; Caporaso, A.

2017-12-01

Stratigraphic pollen analysis was performed on a layer of preserved peat found near the bottom of a 4.75m vibracore taken in 18m of water off the coast of Orange Beach, Alabama. The core was taken from a site where the remains of a previously buried bald cypress (Taxodium distichum) forest was discovered after wave action, likely from Hurricane Ivan in 2004, scoured and removed the overlying Holocene/late Pleistocene sand sheet. Many of the cypress stumps found at the site are still in growth position, and rooted in the preserved terrestrial soils below. Radiocarbon dating of the peat recovered in core DF1 suggests that the sediment is likely Marine Isotope Stage 3 (MIS 3), or earlier. We hypothesize that the site was quickly buried and preserved by floodplain aggradation associated with sea-level rise that occurred near the end of MIS 3. This rare find provides an opportunity to study in situ fossil pollen from a glacial refugium in the Northern Gulf of Mexico. Pollen results from the lowermost sections within the peat layer show an assemblage consistent with a bald cypress/tupelo gum (Nyssa aquatica) backwater. This is eventually replaced by a more open, possibly brackish, environment, dominated by grasses (Poaceae) and sedges (Cyperaceae). During this change however, there is a brief but very interesting period where the pollen assemblage is likely analogous to the modern day Atlantic Coastal Plain Blackwater Levee/Bar Forests of North and South Carolina. In this modern assemblage, as well as the core samples, birch (Betula), oak (Quercus) and bald cypress are the dominant taxa, along with a strong presence of alder (Alnus), grasses and sedges. We hypothesize that these bar forests formed on areas of higher ground, which resulted from floodplain aggradation that accompanied sea level rise at the end of MIS 3.

The evil within? Systemic fungicide application in trees enhances litter quality for an aquatic decomposer-detritivore system.

PubMed

Newton, Kymberly; Zubrod, Jochen P; Englert, Dominic; Lüderwald, Simon; Schell, Theresa; Baudy, Patrick; Konschak, Marco; Feckler, Alexander; Schulz, Ralf; Bundschuh, Mirco

2018-06-05

Waterborne exposure towards fungicides is known to trigger negative effects in aquatic leaf-associated microbial decomposers and leaf-shredding macroinvertebrates. We expected similar effects when these organisms use leaf material from terrestrial plants that were treated with systemic fungicides as a food source since the fungicides may remain within the leaves when entering aquatic systems. To test this hypothesis, we treated black alder (Alnus glutinosa) trees with a tap water control or a systemic fungicide mixture (azoxystrobin, cyprodinil, quinoxyfen, and tebuconazole) at two worst-case application rates. Leaves of these trees were used in an experiment targeting alterations in two functions provided by leaf-associated microorganisms, namely the decomposition and conditioning of leaf material. The latter was addressed via the food-choice response of the amphipod shredder Gammarus fossarum. During a second experiment, the potential impact of long-term consumption of leaves from trees treated with systemic fungicides on G. fossarum was assessed. Systemic fungicide treatment altered the resource quality of the leaf material resulting in trends of increased fungal spore production and an altered community composition of leaf-associated fungi. These changes in turn caused a significant preference of Gammarus for microbially conditioned leaves that had received the highest fungicide treatment over control leaves. This higher food quality ultimately resulted in a higher gammarid growth (up to 300% increase) during the long-term feeding assay. Although the underlying mechanisms still need to be addressed, the present study demonstrates a positive indirect response in aquatic organisms due to systemic pesticide application in a terrestrial system. As the effects from the introduction of plant material treated with systemic fungicides strongly differ from those mediated via other pathways (e.g., waterborne exposure), our study provides a novel perspective of fungicide

Paleofloristic and paleofaunistic analysis of Dudváh River oxbow and implication for Late Holocene paleoenvironmental development of the Žitný ostrov Island (SW Slovakia)

NASA Astrophysics Data System (ADS)

Pišút, Peter; Břízová, Eva; Čejka, Tomáš; Pipík, Radovan

2010-12-01

Žitný ostrov, the largest island of the Danube River (SW Slovakia) gained its present shape in the Neoholocene period. As a result of increased flood and geomorphological Danube river activity dated to 1378-1528 AD, the Lower Dudváh River was abandoned and its alluvium became a part of the Žitný ostrov. Study of a Dudváh terrestrialized paleomeander by means of pollen and macrofossil analysis provides new information about the paleoenvironments of the Danubian Plain. The meander under study was cut-off during the Sub-Boreal period when the land was mostly covered by oak-dominated mixed forest with a notable high frequency of Fagus and Abies. In low-lying depressions, Alnus glutinosa formed typical alder carrs. The largest decline of the mixed forest occurred during the Sub-Atlantic period. Until the mid-19th century the region was strongly influenced by shallow groundwater and periodical floods, as reflected by pollen of aquatics and marsh species. Amongst non-arboreal taxa, pollen of Cyperaceae, Brassicaceae/Cuscuta, Poaceae and Apiaceae prevailed. Local successional changes started with i) stage of abandoned oxbow still with influx of moving water, poor in both macrophytes and molluscs, ii) shallow eutrophic oxbow lake with slowly flowing or stagnant water overgrown with aquatics (Ranunculus subgen. Batrachium, Potamogeton sp., Ceratophyllum demersum etc.) and abundant molluscs, iii) an open marsh dominated by Cyperaceae (mainly Carex riparia) with Atriplex prostrata, supporting diverse molluscan and Ostracod fauna. Present-day habitat is a result of landscape changes, which have been associated with draining, intensified agriculture, ruderalisation and spread of invasive species.

Vegetation and climate history in the Laptev Sea region (arctic Siberia) during Late Quaternary inferred from pollen records

NASA Astrophysics Data System (ADS)

Andreev, A.; Schirrmeister, L.; Tarasov, P.

2009-04-01

A number of permafrost sections dated by 14C, TL, IRSL, and 230U/Th were analysed for pollen. Pollen spectra suggest that wet grass-sedge tundra habitats dominated during an interstadial c. 200-170 ka ago. The climate was rather wet and cold. The pollen spectra reflect sparser grass-sedge vegetation cover during the Late Saalian stadial, c. 170-130 ka BP. Environmental conditions were much more severe compared with the previous interstadial. Open Poaceae and Artemisia communities dominated at the beginning of the Last Interglacial. Some shrubs (Alnus fruticosa, Salix, Betula nana) grew in more protected and wetter places. Climate was rather warm (similar to modern conditions)during this time. Shrub tundra with Alnus fruticosa and Betula nana s.l. dominated in the area during the Eemian climatic optimum, when summer temperatures were 4-5°C higher than today. Early Weichselian pollen records reflect harsh environmental conditions; sparser vegetation (mostly grass and sedge communities) during this time. Middle Weichselian (Karginsky) Interstadial records with dominance of Cyperaceae and Poaceae with some Artemisia and Salix reflects tundra- and steppe-like associations with willow shrubs dominated the area. The climate was relatively moist and warm. A rather high content of algae colonies in the sediments indicates shallow water habitats (e.g. centres of ice wedge polygons). Dominance of Poaceae, Cyperaceae, Artemisia, and Caryophyllaceae pollen with some other herbs is typical for the 40-32 ka BP (climatic optimum) old sediments when open herb dominated the area. High pollen concentrations reflect that dense grass-sedge dominated vegetation; presence of Salix is also characteristic. The records point to climate amelioration during the Middle Weichselian compared to the Early Weichselian. Climate conditions became colder and drier c. 30-26 ka BP. Pollen spectra reflect that sedge-grass-Artemisia with some Caryophyllaceae and Asteraceae dominated the vegetation

Palynostratigraphical correlation of the excavated Miocene lignite seams of the Yataǧan basin (Muǧla Province, south-western Turkey)

NASA Astrophysics Data System (ADS)

Bouchal, Johannes Martin; Grímsson, Friðgeir; Denk, Thomas

2016-04-01

The excavated main lignite seams and overlying lacustrine sediments of the opencast mines Eskihisar, Salihpaşalar, and Tı naz, Muǧla Province, south-western Turkey were investigated using a high taxonomic resolution palynological approach. The Eskihisar section comprises 47m and 56 samples of which 30 were usable for palynological analysis. The Tı naz section comprises 75 m and 29 samples of which 15 were usable for palynological analysis. Finally, the Salihpaşalar section comprises 25 m and 26 samples of which 16 were usable for palynological analysis. The age of the palynological sections is middle to late Miocene based on radiometric dating and vertebrate fossils. In order to investigate dispersed pollen and spores and their botanical affinities a combined light microscopy and scanning electron microscopy approach was used. The rich palynoflora comprises: seven types of algal cysts (Botryococcus, Zygnemataceae), seventeen spore types belonging to Lycopsida (club mosses), Marsileaceae (water-clover), Osmundaceae, Pteridaceae (brake), and Polypodiaceae; 14 types of gymnosperm pollen belonging to Ephedraceae (Mormon tea), Cupressaceae, Pinaceae (Cathaya, cedar, hemlock, pine, spruce); five types of monocotyledone pollen belonging to Poaceae (grasses, common reed), and Typhaceae (bulrush, bur-reed); ca 90 dicotyledone pollen types belonging to Altingiaceae (sweet gum), Amaranthaceae (goosefoot), Anacardiaceae (sumac family), Apiaceae (parsley family), Aquifoliaceae (holly), Asteraceae (sunflower family), Betulaceae (alder, birch, hazel, hophornbeam, hornbeam), Campanulaceae (bellflower family), Cannabaceae (hackberries), Caprifoliaceae (honeysuckle, teasel family), Caryophyllaceae (pink family), Ericaceae (heather family), Eucommiaceae, Euphorbiaceae (spurge family), Fabaceae (bean family), Fagaceae (beech, oak), Geraniaceae (storkbills), Juglandaceae (hickory, walnut, wingnut), Lamiaceae (bagflower), Linaceae (flax), Lythraceae (waterwillow), Malvaceae

Quantum mechanical/molecular mechanical modeling finds Diels-Alder reactions are accelerated less on the surface of water than in water.

PubMed

Thomas, Laura L; Tirado-Rives, Julian; Jorgensen, William L

2010-03-10

Quantum and molecular mechanics calculations for the Diels-Alder reactions of cyclopentadiene with 1,4-naphthoquinone, methyl vinyl ketone, and acrylonitrile have been carried out at the vacuum-water interface and in the gas phase. In conjunction with previous studies of these cycloadditions in dilute solution, a more complete picture of aqueous environmental effects emerges with implications for the origin of observed rate accelerations using heterogeneous aqueous suspensions, "on water" conditions. The pure TIP4P water slab maintains the bulk density and hydrogen-bonding properties in central water layers. The bulk region merges to vacuum over a ca. 5 A band with progressive diminution of the density and hydrogen bonding. The relative free energies of activation and transition structures for the reactions at the interface are found to be intermediate between those calculated in the gas phase and in bulk water; i.e., for the reaction with 1,4-naphthoquinone, the DeltaDeltaG(++) values relative to the gas phase are -3.6 and -7.3 kcal/mol at the interface and in bulk water, respectively. Thus, the results do not support the notion that a water surface is more effective than bulk water for catalysis of such pericyclic reactions. The trend is in qualitative agreement with expectations based on density considerations and estimates of experimental rate constants for the gas phase, a heterogeneous aqueous suspension, and a dilute aqueous solution for the reaction of cyclopentadiene with methyl vinyl ketone. Computed energy pair distributions reveal a uniform loss of 0.5-1.0 hydrogen bond for the reactants and transition states in progressing from bulk water to the vacuum-water interface. Orientational effects are apparent at the surface; e.g., the carbonyl group in the methyl vinyl ketone transition structure is preferentially oriented into the surface. Also, the transition structure for the 1,4-naphthoquinone case is buried more in the surface, and the free energy of

The [C{sub 6}H{sub 10}]{sup {sm{underscore}bullet}+} hypersurface: The parent radical cation Diels-Alder reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoffmann, M.; Schaefer, H.F. III

1999-07-21

Various possible reaction pathways between ethene and butadiene radical cation (cis- and trans-), have been investigated at different levels of theory up to UCCSD(T)/DZP/UMP2(fc)/DZP and with density functional theory at B3LYP/DZP. A stepwise addition involving open chain intermediates and leading to the Diels-Alder product, the cyclohexene radical cation, was found to have a total activation barrier {Delta}G{sup 298{ne}} = 6.3 kcal mol{sup {minus}1} and a change in free Gibbs energy, {Delta}G{sup 298}, of {minus}33.5 kcal mol{sup {minus}1}. On the E{degree} potential energy surface, all transition states are lower in energy than separated ethene and butadiene, the exothermicity {Delta}E = -45.6more » kcal mol{sup {minus}1}. A more direct path could be characterized as stepwise with one intermediate only at the SCF level but not at electron-correlated levels and hence might actually be a concerted strongly asynchronous addition with a very small or no activation barrier (UCCSD(T)/DZP/UHF/6-31G* gives a {Delta}G{sup 298{ne}} of 0.8 kcal mol{sup {minus}1}). The critical step for another alternative, the cyclobutanation-vinylcyclobutane/cyclohexene rearrangement, is a 1,3-alkyl shift which involves a barrier ({Delta}G{sup 298{ne}}) only 1.7 kcal mol{sup {minus}1} higher than that of stop use addition for both cis-, and trans-butadiene radical cation. However, from the (ethene and trans-butadiene) reactions, ring expansion of the vinylcyclobutane radical cation intermediate, to a methylene cyclopentane radical cation, requires an activation only 1.3 kcal mol{sup {minus}1} larger than for (trans-butadiene radical). While cis/trans isomerization of free butadiene radical cation requires a high activation (24.9 kcal mol{sup {minus}1}), a reaction sequence involving addition of ethene (to stepwise give an open chain intermediate and vinyl cyclobutane radical cation) has a barrier of only 3.5 kcal mol{sup {minus}1} ({Delta}G{sup 298{ne}}). This sequence also makes ethene

Chip Debarking of Several Western Species

Treesearch

William A. Hillstrom

1974-01-01

Discusses processing and conditioning treatments before and aftger compression debarking of western hemlock, Douglas fir, red alder, and bigleaf maple. Bark removal and wood recovery from red alder far exceeded the other species tested. Approximately 90 percent of the wood fiber input was recovered at a residual bark content of less than 2 percent by weight.

Revision of the genus Turris Batsch, 1789 (Gastropoda: Conoidea: Turridae) with the description of six new species

PubMed Central

Kilburn, Richard N.; Fedosov, Alexander E.; Olivera, Baldomero M.

2012-01-01

The taxonomy of the genus Turris Batsch, 1789, type genus of the family Turridae, widespread in shallow-water habitats of tropic Indo-Pacific, is revised. A total of 31 species of Turris, are here recognized as valid. New species described: Turris chaldaea, Turris clausifossata, Turris guidopoppei, Turris intercancellata, Turris kantori, T. kathiewayae. Homonym renamed: Turris bipartita nom. nov. for Pleurotoma variegata Kiener, 1839 (non Philippi, 1836). New synonymies: Turris ankaramanyensis Bozzetti, 2006 = Turris tanyspira Kilburn, 1975; Turris imperfecti, T. nobilis, T. pulchra and T. tornatum Röding, 1798, and Turris assyria Olivera, Seronay & Fedosov, 2010 = T. babylonia; Turris dollyi Olivera, 2000 = Pleurotoma crispa Lamarck, 1816; Turris totiphyllis Olivera, 2000 = Turris hidalgoi Vera-Peláez, Vega-Luz & Lozano-Francisco, 2000; Turris kilburni Vera-Peláez, Vega-Luz & Lozano-Francisco, 2000 = Turris pagasa Olivera, 2000; Turris (Annulaturris) munizi Vera-Peláez, Vega-Luz & Lozano-Francisco, 2000 = Gemmula lululimi Olivera, 2000. Revised status: Turris intricata Powell, 1964, Pleurotoma variegata Kiener, 1839 (non Philippi, 1836) and Pleurotoma yeddoensis Jousseaume, 1883, are regarded as full species (not subspecies of Turris crispa). Neotype designated: For Pleurotoma garnonsii Reeve, 1843, to distinguish it from Turris garnonsii of recent authors, type locality emended to Zanzibar. New combination: Turris orthopleura Kilburn, 1983, is transferred to genus Makiyamaia, family Clavatulidae. PMID:23847408

Effects of invasive plant species on pollinator service and reproduction in native plants at Acadia National Park

USGS Publications Warehouse

Stubbs, C.J.; Drummond, F.; Ginsberg, H.

2007-01-01

Invasive plant species can have profound negative effects on natural communities by competively excluding native species. Berberis thunbergii (Japanese barberry), Frangula alnus (glossy or alder buckthorn) and Lythrum salicaria (purple loosestrife) are invasive species known to reduce native plant diversity and are thus of great concern to Acadia National Park. Pollinators visit them for nectar and pollen. The effects of invasive plant species on pollinator behavior were investigated by comparing pollinator visitation to co-flowering native and invasive species with visitation to native species growing alone. The effect of invasives on pollination of native plants was studied by comparing fruit set in patches of the native species growing near invasives with patches far from invasive species in Acadia National Park. The coflowering pairs were as follows: in the spring native Vaccinium angustifolium (lowbush blueberry) was paired with B. thunbergii; in early summer native Viburnum nudum (wild raisin) was paired with F. alnus ; in late summer native Spiraea alba (meadowsweet) was paired with L. salicaria. We investigated whether these invasives competed with native plants for pollinators in Acadia and thus negatively affected native plant reproduction. Our objectives were to determine: 1) the influence, if any, of each invasive on pollinator visitation to a co-flowering native species, 2) factors that might affect visitation, 3) invasive pollen transfer to native plants, and 4) whether invasives influence native plant reproduction (fruit set). Our findings indicate that at times the number of flower visitors to natives was lower or the species composition of visitors different when invasives were present, that invasives sometimes attracted more pollinators, that generally the invasives were more rewarding as far as nectar and pollen availability for pollinators, and that generally native plant fruit set and seed set was not significantly lowered in the presence of

Micro-flow photosynthesis of new dienophiles for inverse-electron-demand Diels–Alder reactions. Potential applications for pretargeted in vivo PET imaging† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c6sc02933g Click here for additional data file.

PubMed Central

Billaud, Emilie M. F.; Shahbazali, Elnaz; Ahamed, Muneer; Cleeren, Frederik; Noël, Timothy; Koole, Michel; Verbruggen, Alfons; Hessel, Volker

2017-01-01

Pretargeted PET imaging has emerged as an effective two-step in vivo approach that combines the superior affinity and selectivity of antibodies with the rapid pharmacokinetics and favorable dosimetry of smaller molecules radiolabeled with short-lived radionuclides. This approach can be based on the bioorthogonal inverse-electron-demand Diels–Alder (IEDDA) reaction between tetrazines and trans-cyclooctene (TCO) derivatives. We aimed to develop new [18F]TCO–dienophiles with high reactivity for IEDDA reactions, and favorable in vivo stability and pharmacokinetics. New dienophiles were synthesized using an innovative micro-flow photochemistry process, and their reaction kinetics with a tetrazine were determined. In vivo stability and biodistribution of the most promising 18F-radiolabeled-TCO-derivative ([18F]3) was investigated, and its potential for in vivo pretargeted PET imaging was assessed in tumor-bearing mice. We demonstrated that [18F]3 is a suitable dienophile for IEDDA reactions and for pretargeting applications. PMID:28451267

Computational Insights into an Enzyme-Catalyzed [4+2] Cycloaddition

PubMed Central

2017-01-01

The enzyme SpnF, involved in the biosynthesis of spinosyn A, catalyzes a formal [4+2] cycloaddition of a 22-membered macrolactone, which may proceed as a concerted [4+2] Diels–Alder reaction or a stepwise [6+4] cycloaddition followed by a Cope rearrangement. Quantum mechanics/molecular mechanics (QM/MM) calculations combined with free energy simulations show that the Diels–Alder pathway is favored in the enzyme environment. OM2/CHARMM free energy simulations for the SpnF-catalyzed reaction predict a free energy barrier of 22 kcal/mol for the concerted Diels–Alder process and provide no evidence of a competitive stepwise pathway. Compared with the gas phase, the enzyme lowers the Diels–Alder barrier significantly, consistent with experimental observations. Inspection of the optimized geometries indicates that the enzyme may prearrange the substrate within the active site to accelerate the [4+2] cycloaddition and impede the [6+4] cycloaddition through interactions with active-site residues. Judging from partial charge analysis, we find that the hydrogen bond between the Thr196 residue of SpnF and the substrate C15 carbonyl group contributes to the enhancement of the rate of the Diels–Alder reaction. QM/MM simulations show that the substrate can easily adopt a reactive conformation in the active site of SpnF because interconversion between the C5–C6 s-trans and s-cis conformers is facile. Our QM/MM study suggests that the enzyme SpnF does behave as a Diels-Alderase. PMID:29131960

Nitrous oxide fluxes from tree stems of temperate forests

NASA Astrophysics Data System (ADS)

Wen, Yuan; Corre, Marife D.; Rachow, Christine; Veldkamp, Edzo

2017-04-01

Although trees are recognized as conduits of soil-generated N2O, little is known about N2O fluxes from mature trees under field conditions and thier contributions to total forest N2O fluxes. Here, we quantified in situ stem N2O fluxes from mature alder trees on poorly-drained soil and mature beech and spruce trees on well-drained soils in Solling, Germany from March to October 2015. Soil N2O fluxes, soil N2O concentrations at 40-cm depth, and soil and climatic variables known to influence N2O fluxes were also measured concurrently with the stem N2O fluxes. Alder, beech and spruce consistently emitted N2O via stems and all displayed higher emission rates in summer than in spring and in autumn. Stem N2O fluxes from alder stand were higher than those from beech and spruce stands (P < 0.01), which was attributed to the presence of aerenchyma and lenticels as well as higher soil water content and soil C and N availability in the alder stand (P < 0.01-0.05). The correlations of stem N2O fluxes from alder with soil N2O fluxes, soil N2O concentrations, soil and air temperature and vapor pressure deficit (R = 0.60 - 0.90, P < 0.01-0.05) suggest that N2O transport in alder was facilitated by a combination of passive gas diffusion through aerenchyma and active transport of dissolved N2O through sap flow. In the beech and spruce stands, correlations of stem N2O fluxes with soil and air temperature and vapor pressure deficit (R = 0.57 - 0.78, P < 0.01-0.07) suggest that active transport of dissolved N2O via xylem sap was the major mechanism for stem N2O emissions in upland trees. Stem N2O fluxes represented 8-11% of the total (soil + stem) N2O fluxes in the spruce and beech stands whereas in the alder stand, with its large soil N2O emission, stem emission contributed only 1% of the total flux. Our results suggest that the relative contribution of tree-mediated N2O fluxes is more important in upland trees than in wetland trees.

Interplanting woody nurse crops promotes differential growth of black walnut saplings

Treesearch

J. O. Dawson; J. W. Van Sambeek

1993-01-01

Interplanting black walnut (Juglans nigra) with four different nitrogen fixing, woody nurse crops (Alnus glutinosa, Elaeagnus umbellata, E. angustifolia or Caragana arborescens) increased annual walnut height and stem diameter (dbh) growth overall by as much as 50% and...

Comparative Investigation of Copper Tolerance and Identification of Putative Tolerance Related Genes in Tardigrades.

PubMed

Hygum, Thomas L; Fobian, Dannie; Kamilari, Maria; Jørgensen, Aslak; Schiøtt, Morten; Grosell, Martin; Møbjerg, Nadja

2017-01-01

Tardigrades are microscopic aquatic animals renowned for their tolerance toward extreme environmental conditions. The current study is the first to investigate their tolerance toward heavy metals and we present a novel tardigrade toxicant tolerance assay based on activity assessments as a measure of survival. Specifically, we compare tolerance toward copper in four species representing different evolutionary lineages, habitats and adaptation strategies, i.e., a marine heterotardigrade, Echiniscoides sigismundi , a limno-terrestrial heterotardigrade, Echiniscus testudo , a limno-terrestrial eutardigrade, Ramazzottius oberhaeuseri , and a marine eutardigrade, Halobiotus crispae . The latter was sampled at a time of year, when the population is predominantly represented by aberrant P1 cysts, while the other species were in normal active states prior to exposure. Based on volume measurements and a general relation between body mass and copper tolerance, expected tardigrade EC50 values were estimated at 0.5-2 μg l -1 . Following 24 h of exposure, tolerance was high with no apparent link to lineage or habitat. EC50s (95% CI), 24 h after exposure, were estimated at 178 (168-186) and 310 (295-328) μg l -1 , respectively, for E. sigismundi and R. oberhaeuseri , whereas E. testudo and H. crispae were less affected. Highest tolerance was observed in H. crispae with a mean ± s.e.m . activity of 77 ± 2% ( n = 3) 24 h after removal from ~3 mg l -1 copper, suggesting that tardigrade cysts have increased tolerance toward toxicants. In order to identify putative tolerance related genes, an E. sigismundi transcriptome was searched for key enzymes involved in osmoregulation, antioxidant defense and copper metabolism. We found high expression of Na/K ATPase and carbonic anhydrase, known targets for copper. Our transcriptome, furthermore, revealed high expression of antioxidant enzymes, copper transporters, ATOX1, and a Cu-ATPase. In summary, our results indicate that tardigrades

Design and Synthesis of a Library of Tetracyclic Hydroazulenoisoindoles

PubMed Central

Brummond, Kay M.; Mao, Shuli; Shinde, Sunita N.; Johnston, Paul J.; Day, Billy W.

2009-01-01

Forty-four tetracyclic hydroazulenoisoindoles were synthesized via a tandem cyclopropanation/Cope rearrangement followed by a Diels-Alder sequence from easily available five-membered cyclic cross-conjugated trienones. These trienones were obtained from two different routes depending upon whether R1 and R2 are alkyl or amino acid derived functional groups, via a rhodium(I)-catalyzed cycloisomerization reaction. In order to increase diversity, four maleimides and two 1,2,4-triazoline-3,5-diones were used as dienophiles in the Diels-Alder step. Several Diels-Alder adducts were further reacted under palladium-catalyzed hydrogenation conditions, leading to a diastereoselective reduction of the trisubstituted double bond. This library has demonstrated rapid access to a variety of structurally complex natural product-like compounds via stereochemical diversity and building block diversity approaches. PMID:19366169

Allelopathic effects of juglone on germination and growth of several herbaceous and woody species

Treesearch

W.J. Rietveld

1983-01-01

Laboratory experiments were conducted to determine juglone sensitivity of 16 species (Trifolium incarnatum, Coronilla varia, Vicia villosa, Lespedeza stipulacea, L. cuneata, Acer ginnala, Caragana arboreseens, Elaegnus angustifolia, E. umbellata, Lonieera maackii, Quercus alba, Fraxinus americana, Liriodendron tulipifera, Alnus glutinosa, Pinus strobus...

Morphological, molecular and ecological aspects of the South American hypogeous fungi Alpova austroalnicola sp. nov.

Treesearch

Eduardo R. Nouhra; Laura S. Domínguez; Alejandra G. Becerra; James M. Trappe

2005-01-01

Field studies in Argentina's Yunga District revealed Alpova austroalnicola sp. nov., a hypogeous fungus associated with Alnus acuminata ssp, acuminata. Morphological and molecular studies based on amplification and sequencing of the nuclear LSU rDNA gene showed its unique identity within ...

Interactions among soil biology, nutrition, and performance of actinorhizal plant species in the H.J. Andrews Experimental Forest of Oregon.

Treesearch

N.S. Rojas; D.A. Perry; C.Y. Li; L.M. Ganio

2002-01-01

The study examined the effect of Frankia, macronutrients, micronutrients, mycorrhizal fungi, and plant-growth-promoting fluorescent Pseudomonas sp. on total biomass, nodule weight, and nitrogen fixation of red aider (Alnus rubra) and snowbrush (Ceanothus velutinus) under greenhouse conditions. The soil...

Internal distribution of Cd in lettuce and resulting effects on Cd trophic transfer to the snail: Achatina fulica.

PubMed

Li, Cheng-Cheng; Dang, Fei; Cang, Long; Zhou, Dong-Mei; Peijnenburg, Willie J G M

2015-09-01

The mechanisms underlying Cd trophic transfer along the soil-lettuce-snail food chain were investigated. The fate of Cd within cells, revealed by assessment of Cd chemical forms and of subcellular partitioning, differed between the two examined lettuce species that we examined (L. longifolia and L. crispa). The species-specific internal Cd fate not only influenced Cd burdens in lettuce, with higher Cd levels in L. crispa, but also affected Cd transfer efficiency to the consumer snail (Achatina fulica). Especially, the incorporation of Cd chemical forms (Cd in the inorganic, water-soluble and pectates and protein-integrated forms) in lettuce could best explain Cd trophic transfer, when compared to dietary Cd levels alone and/or subcellular Cd partitioning. Trophically available metal on the subcellular partitioning base failed to shed light on Cd transfer in this study. After 28-d of exposure, most Cd was trapped in the viscera of Achatina fulica, and cadmium bio-magnification was noted in the snails, as the transfer factor of lettuce-to-snail soft tissue was larger than one. This study provides a first step to apply a chemical speciation approach to dictate the trophic bioavailability of Cd through the soil-plant-snail system, which might be an important pre-requisite for mechanistic understanding of metal trophic transfer. Copyright © 2015 Elsevier Ltd. All rights reserved.

Exploiting the Electrophilic and Nucleophilic Dual Role of Nitrile Imines: One-Pot, Three-Component Synthesis of Furo[2,3-d]pyridazin-4(5H)-ones.

PubMed

Giustiniano, Mariateresa; Mercalli, Valentina; Amato, Jussara; Novellino, Ettore; Tron, Gian Cesare

2015-08-21

An expeditious multicomponent reaction to synthesize tetrasubstituted furo[2,3-d]pyridazin-4(5H)-ones is reported. In brief, hydrazonoyl chlorides react with isocyanoacetamides, in the presence of TEA, to give 1,3-oxazol-2-hydrazones which, without being isolated, can react with dimethylacetylene dicarboxylate to afford furo[2,3-d]pyridazin-4(5H)-ones with an unprecedented level of complexity in a triple domino Diels-Alder/retro-Diels-Alder/lactamization reaction sequence.

Processing Conjugated-Diene-Containing Polymers

NASA Technical Reports Server (NTRS)

Bell, Vernon L.; Havens, Stephen J.

1987-01-01

Diels-Alder reaction used to cross-linked thermoplastics. Process uses Diels-Alder reaction to cross-link and/or extend conjugated-diene-containing polymers by reacting them with bis-unsaturated dienophiles results in improved polymer properties. Quantities of diene groups required for cross-linking varies from very low to very high concentrations. Process also used to extend, or build up molecular weights of, low-molecular-weight linear polymers with terminal conjugated dienic groups.

[Maples at the sub-Alpine vegetation belt: a long history].

PubMed

David, F; Barbero, M

2001-02-01

Pollen analysis was carried out on lacustrine sediment of a small hollow (15 m x 25 m) at the treeless sub-Alpine belt (202 m) of the inner Maurienne valley in the northern French Alps. A 2,500-year-long maple settlement was demonstrared. Three AMS dates of terrestrial plant macroremains support the chronology. First, Betula and Salix spread prior to 9,000 C14 BP. The first pollen grains of Acer, Abies and Pinus cembra are quoted at 8,600 C14 BP. High frequencies of Alnus glutinosa/incana (20%) and Acer (10%) show that mixed communities of Acer and Alnus persisted above the mountainous Abies forest between 7,490 and 5,850 C14 BP. After 5,850 C14 BP, the decrease in Acer stands could be attributed to fire as suggested by the strong increase in Betula and by the delayed expansion of Pinus cembra.

National Research Council Resident Research Associateship (NRC-RRA) program

DTIC Science & Technology

1988-08-01

Davis, C. J. Dymek, J. J. P. Stewart, H. P. Clark, W. J. Lauderdale, J. Am. Chem. Soc., 107, 5041-5046 (1985). 7. "Mechanism of the Diels - Alder ...Package" Dewar Research Group and J. J. P. Stewart, Quantum Chemistry Program Exchange, no. 506, nn, nnn, (1986) 16. "Mechanism of the Diels - Alder ...Kvisle, 0. Nirisen, M. Ystenes, and H. A. Oye, Proceedings of 1986 International Symposium on Transition Metals Catalyzed Polymerizations, Institute of

Regiochemically controlled synthesis of a β-4-β' [70]fullerene bis-adduct

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cerón, Maira R.; Castro, Edison; Neti, Venkata S. Pavan K.

2016-12-22

A β-4-β' C 70 bis-adduct regioisomer and an uncommon mono-adduct β-malonate C 70 derivative were synthesized by using a Diels–Alder cycloaddition followed by an addition–elimination of bromo-ethylmalonate and a retro-Diels–Alder cycloaddition reaction. Here, we also report the regioselective synthesis and spectroscopic characterization of C s-symmetric tris- and C 2v-symmetric tetra-adducts of C 70, which are the precursors of the mono- and bis-adduct final products.

High-resolution paleoclimatology of the coastal margin of northernmost California during the past 7,300 years

NASA Astrophysics Data System (ADS)

Barron, J. A.; Heusser, L. E.; Addison, J. A.; Burky, D.; Kusler, J. E.; Finney, B.

2013-12-01

Piston core TN062 0550, located 13 km offshore of Eureka, California (40.866 deg. N, 124.572 deg. W, 550 m water depth), contains a continuous high-resolution climate record of the past 7,300 yr. Deposition occurred at nearly constant sedimentation rates averaging 94 cm/kyr based on 14C AMS dating of planktonic foraminifers. Pollen and marine ecosystem proxies (diatoms, silicoflagellates, wt. percent biogenic silica) studied at 50-70 yr sample resolution show a stepwise development of the climate/ oceanographic system off northernmost California. The relative contributions of Sequoia sempervirens (coastal redwood) pollen, a proxy for coastal fog associated with offshore upwelling, and biogenic silica concentrations (a proxy for siliceous export productivity) increase (two fold and three fold, respectively) in successive steps at ~5,000 yr BP and from ~2,400 to 2,000 yr BP. These increases are interpreted to reflect a progressive intensification of spring upwelling based on modern observations of the California Current system. At 5,000 yr BP diatom assemblages change from an assorted mixture of warm, temperate, and cool-water taxa to a low diversity temperate-oceanic assemblage dominated by Thalassionema spp. At ~2,400 yr BP the diatom assemblage transitions to a mixture of nearshore upwelling taxa and taxa associated with the central North Pacific Gyre. Silicoflagellate assemblages undergo a similar increase in the representation of modern seasonal proxies at ~3,000 yr BP that may reflect intensified ENSO variability. A two-fold increase in the relative contributions of Quercus (oak) and riparian Alnus (alder) pollen between ~3,800 and 2,000 yr BP likely signals a period of enhanced fluvial runoff associated with increased winter precipitation. Given the present day association of the Eel River system with the northwestern half of the western US winter precipitation dipole, these pollen data suggest that the ~3,800 and 2,000 yr interval was dominated by protracted

Mapping allergenic pollen vegetation in UK to study environmental exposure and human health.

PubMed

McInnes, Rachel N; Hemming, Deborah; Burgess, Peter; Lyndsay, Donna; Osborne, Nicholas J; Skjøth, Carsten Ambelas; Thomas, Sam; Vardoulakis, Sotiris

2017-12-01

Allergenic pollen is produced by the flowers of a number of trees, grasses and weeds found throughout the UK. Exposure to such pollen grains can exacerbate pollen-related asthma and allergenic conditions such as allergic rhinitis (hay fever). Maps showing the location of these allergenic taxa have many applications: they can be used to provide advice on risk assessments; combined with health data to inform research on health impacts such as respiratory hospital admissions; combined with weather data to improve pollen forecasting systems; or as inputs to pollen emission models. In this study we present 1km resolution maps of 12 taxa of trees, grass and weeds found in the UK. We have selected the main species recorded by the UK pollen network. The taxa mapped in this study were: Alnus (alder), Fraxinus (ash), Betula (birch), Corylus (hazel), Quercus (oak), Pinus (pine) and Salix (willow), Poaceae (grass), Artemisia (mugwort), Plantago (plantain), Rumex (dock, sorrels) and Urtica (nettle). We also focus on one high population centre and present maps showing local level detail around the city of London. Our results show the different geographical distributions of the 12 taxa of trees, weeds and grass, which can be used to study plants in the UK associated with allergy and allergic asthma. These maps have been produced in order to study environmental exposure and human health, although there are many possible applications. This novel method not only provides maps of many different plant types, but also at high resolution across regions of the UK, and we uniquely present 12 key plant taxa using a consistent methodology. To consider the impact on human health due to exposure of the pollen grains, it is important to consider the timing of pollen release, and its dispersal, as well as the effect on air quality, which is also discussed here. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Late Glacial-Holocene Pollen-Based Vegetation History from Pass Lake, Prince of Wales Island, Southeastern Alaska

USGS Publications Warehouse

Ager, Thomas A.; Rosenbaum, Joseph G.

2009-01-01

A radiocarbon-dated history of vegetation development since late Wisconsin deglaciation has been reconstructed from pollen evidence preserved in a sediment core from Pass Lake on Prince of Wales Island, southeastern Alaska. The shallow lake is in the south-central part of the island and occupies a low pass that was filled by glacial ice of local origin during the late Wisconsin glaciation. The oldest pollen assemblages indicate that pine woodland (Pinus contorta) had developed in the area by ~13,715 cal yr B.P. An abrupt decline in the pine population, coinciding with expansion of alder (Alnus) and ferns (mostly Polypodiaceae) began ~12,875 yr B.P., and may have been a response to colder, drier climates during the Younger Dryas climatic interval. Mountain hemlock (Tsuga mertensiana) began to colonize central Prince of Wales Island by ~11,920 yr B.P. and was soon followed by Sitka spruce (Picea sitchensis). Pollen of western hemlock (Tsuga heterophylla) began to appear in Pass Lake sediments soon after 11,200 yr B.P. The abundance of western hemlock pollen in the Pass Lake core during most of the Holocene appears to be the result of wind transport from trees growing at lower altitudes on the island. The late Holocene pollen record from Pass Lake is incomplete because of one or more unconformities, but the available record suggests that a vegetation change occurred during the late Holocene. Increases in pollen percentages of pine, cedar (probably yellow cedar, Chamaecyparis nootkatensis), and heaths (Ericales) suggest an expansion of muskeg vegetation occurred in the area during the late Holocene. This vegetation change may be related to the onset of cooler, wetter climates that began as early as ~3,774 yr B.P. in the region. This vegetation history provides the first radiocarbon-dated Late Glacial-Holocene terrestrial paleoecological framework for Prince of Wales Island. An analysis of magnetic properties of core sediments from Pass Lake suggests that unconformities

Preservation of cycad and Ginkgo pollen

USGS Publications Warehouse

Frederiksen, N.O.

1978-01-01

Pollen grains of Ginkgo, Cycas, and Encephalartos were chemically treated together with pollen of Quercus, Alnus, and Pinus, the latter three genera being used as standards. The experiments showed that: (1) boiling the pollen for 8-10 hours in 10% KOH had little if any effect on any of the grains; (2) lengthy acetolysis treatment produced some degradation or corrosion, particularly in Ginkgo and Cycas, but the grains of even these genera remained easily recognizable; (3) oxidation with KMnO4 followed by H2O2 showed that pollen of Ginkgo, Cycas, and Encephalartos remains better preserved than that of Quercus and Alnus, and although Ginkgo and Encephalartos probably are slightly less resistant to oxidation than Pinus, no great differences exists between these monosulcate types and Pinus. Thus the experiments show that, at least for sediments low in bacteria, cycad and Ginkgo pollen should be well represented in the fossil record as far as their preservational capabilities are concerned. ?? 1978.

Meteorological factors and air pollution in Lithuanian forests: possible effects on tree condition.

PubMed

Ozolincius, Remigijus; Stakenas, Vidas; Serafinaviciute, Brigita

2005-10-01

This study investigates changes in tree condition and environmental factors in Lithuania during the active growing season in 1991-2001. The average crown defoliation and the proportion of healthy trees of Pinus sylvestris, Picea abies, Betula sp., Fraxinus excelsior, Alnus incana, Alnus glutinosa, Populus tremula, and Quercus robur, meteorological (average temperature, amount of precipitation, hydrothermal coefficient) and air pollution data (acidity of precipitation, concentrations of SO2, NO2 and exposure of O3) were analysed. During the period 1991-2001 the condition of Pinus sylvestris, Populus tremula showed a tendency of improvement, while defoliation of Fraxinus excelsior significantly increased. The proportion of healthy trees correlated well with the average temperature and O3 (AOT40), while defoliation correlated well with the acidity of precipitation and the concentrations of SO2 and NO2. Deciduous species appeared to be more sensitive to O3 exposure and conifers to the concentrations of SO2 and NO2.

"Clickable" Polymeric Nanofibers through Hydrophilic-Hydrophobic Balance: Fabrication of Robust Biomolecular Immobilization Platforms.

PubMed

Kalaoglu-Altan, Ozlem I; Sanyal, Rana; Sanyal, Amitav

2015-05-11

Fabrication of hydrophilic polymeric nanofibers that undergo facile and selective functionalization through metal catalyst-free Diels-Alder "click" reaction in aqueous environment is outlined. Electrospinning of copolymers containing an electron-rich furan moiety, hydrophobic methyl methacrylate units and hydrophilic poly(ethylene glycol)s as side chains provide specifically functionalizable yet antibiofouling fibers that remain stable in aqueous media due to appropriate hydrophobic hydrophilic balance. Efficient functionalization of these nanofibers is accomplished through the Diels-Alder reaction by exposing them to maleimide-containing molecules and ligands. Diels-Alder conjugation based functionalization is demonstrated through attachment of fluorescein-maleimide and a maleimide tethered biotin ligand. Biotinylated nanofibers were utilized to mediate immobilization of the protein streptavidin, as well as streptavidin coated quantum dots. Facile fabrication from readily available polymers and their effective functionalization under mild and reagent-free conditions in aqueous media make these "clickable" nanofibers attractive candidates as functionalizable scaffolds for various biomedical applications.

Comparative Investigation of Copper Tolerance and Identification of Putative Tolerance Related Genes in Tardigrades

PubMed Central

Hygum, Thomas L.; Fobian, Dannie; Kamilari, Maria; Jørgensen, Aslak; Schiøtt, Morten; Grosell, Martin; Møbjerg, Nadja

2017-01-01

Tardigrades are microscopic aquatic animals renowned for their tolerance toward extreme environmental conditions. The current study is the first to investigate their tolerance toward heavy metals and we present a novel tardigrade toxicant tolerance assay based on activity assessments as a measure of survival. Specifically, we compare tolerance toward copper in four species representing different evolutionary lineages, habitats and adaptation strategies, i.e., a marine heterotardigrade, Echiniscoides sigismundi, a limno-terrestrial heterotardigrade, Echiniscus testudo, a limno-terrestrial eutardigrade, Ramazzottius oberhaeuseri, and a marine eutardigrade, Halobiotus crispae. The latter was sampled at a time of year, when the population is predominantly represented by aberrant P1 cysts, while the other species were in normal active states prior to exposure. Based on volume measurements and a general relation between body mass and copper tolerance, expected tardigrade EC50 values were estimated at 0.5–2 μg l−1. Following 24 h of exposure, tolerance was high with no apparent link to lineage or habitat. EC50s (95% CI), 24 h after exposure, were estimated at 178 (168–186) and 310 (295–328) μg l−1, respectively, for E. sigismundi and R. oberhaeuseri, whereas E. testudo and H. crispae were less affected. Highest tolerance was observed in H. crispae with a mean ± s.e.m. activity of 77 ± 2% (n = 3) 24 h after removal from ~3 mg l−1 copper, suggesting that tardigrade cysts have increased tolerance toward toxicants. In order to identify putative tolerance related genes, an E. sigismundi transcriptome was searched for key enzymes involved in osmoregulation, antioxidant defense and copper metabolism. We found high expression of Na/K ATPase and carbonic anhydrase, known targets for copper. Our transcriptome, furthermore, revealed high expression of antioxidant enzymes, copper transporters, ATOX1, and a Cu-ATPase. In summary, our results indicate that tardigrades

Leaf Mass Area, Leaf Carbon and Nitrogen Content, Kougarok Road and Teller Road, Seward Peninsula, Alaska, 2016

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shawn Serbin; Alistair Rogers; Kim Ely

Carbon, Nitrogen and Leaf Mass Area of leaves sampled from locations on the Kougarok Rd (transect A) and Teller Rd NGEE Arctic study sites, Seward Peninsula, Alaska. Species include: Alnus viridis spp. fruticosa, Arctostaphylos rubra, Betula glandulosa, Chamerion latifolium, Petasites frigidus, Salix alaxensis, Salix glauca, Salix pulchra, Salix richardsonii and Vaccinium uliginosum.

Biological Modulation of Upper Ocean Physics: Simulating the Biothermal Feedback Effect in Monterey Bay, California

DTIC Science & Technology

2014-04-08

sea (yellow substance) in the UV and visible domains, Limnol. Oceanogr., 26(1), 43–53. Cahill, B., O. Schofield, R. Chant, J. Wilkin , E. Hunter, S...1974), Carbon dioxide exchange of Alnus rubra, A mathematical model, Oecologia Berl., 17, 281–291. Wu, Y., C. C. L. Tang , S. Sathyendranath, and T

Total synthesis of the thiopeptide antibiotic amythiamicin D.

PubMed

Hughes, Rachael A; Thompson, Stewart P; Alcaraz, Lilian; Moody, Christopher J

2005-11-09

The thiopeptide (or thiostrepton) antibiotics are a class of sulfur containing highly modified cyclic peptides with interesting biological properties, including reported activity against MRSA and malaria. Described herein is the total synthesis of the thiopeptide natural product amythiamicin D, which utilizes a biosynthesis-inspired hetero-Diels-Alder route to the pyridine core of the antibiotic as a key step. Preliminary studies using a range of serine-derived 1-ethoxy-2-azadienes established that hetero-Diels-Alder reaction with N-acetylenamines proceeded efficiently under microwave irradiation to give 2,3,6-trisubstituted pyridines. The thiazole building blocks of the antibiotic were obtained by either classical Hantzsch reactions or by dirhodium(II)-catalyzed chemoselective carbene N-H insertion followed by thionation, and were combined to give the bis-thiazole that forms the left-hand fragment of the antibiotic. The key Diels-Alder reaction of a tris-thiazolyl azadiene with benzyl 2-(1-acetylaminoethenyl)thiazole-4-carboxylate gave the core tetrathiazolyl pyridine, which was elaborated into the natural product by successive incorporation of glycine and bis-thiazole fragments followed by macrocyclization.

Synthesis of tripeptide derivatized cyclopentadienyl complexes of technetium and rhenium as radiopharmaceutical probes.

PubMed

Nadeem, Qaisar; Can, Daniel; Shen, Yunjun; Felber, Michael; Mahmood, Zaid; Alberto, Roger

2014-03-28

We describe the syntheses of half-sandwich complexes of the type [(η(5)-Cp(CONH-R))M(CO)3] with M = Re or (99m)Tc. The R group represents different tri-peptides (tpe) which display high binding affinities for oligopeptide transporters PEPT2. The (99m)Tc complexes were prepared directly from [(99m)Tc(OH2)3(CO)3](+) and Diels-Alder dimerized, cyclopentadienyl derivatized peptides in water. This approach corroborates the feasibility of metal-mediated retro Diels-Alder reactions for the preparation of not only small molecules but also peptides carrying a [(η(5)-Cp)(99m)Tc(CO)3] tag. We synthesized the Diels-Alder product [(HCpCONH-tpe)2] from Thiele's acid [(η(5)-HCpCOOH)2] via double peptide coupling. The Re-complexes [(η(5)-CpCONH-tpe)Re(CO)3] were obtained by attaching [(Cp-COOH)Re(CO)3] directly to the N-terminus of peptides as received from SPPS. The authenticity of the (99m)Tc-complexes is confirmed by chromatographic comparison with the corresponding rhenium complexes, fully characterized by spectroscopic techniques.

Stream restoration at Denali National Park and Preserve

USGS Publications Warehouse

Densmore, Roseann V.; Karle, Kenneth F.

1999-01-01

Placer mining for gold has severely disturbed many riparian ecosystems in northern regions. We are conducting a long-term project to test methods to promote restoration of a placer-mined watershed in Denali National Park and Preserve. The project included hydrological restoration of the unstable and excessively confined stream with heavy equipment. We stabilized the floodplain with bioengineering techniques, including alder and willow brush bars anchored laterally to the channel and willow cuttings along the channel. A moderate flood near the end of construction showed that the brush bars provided substantial protection, but some bank erosion and changes in slope and sinuosity occurred. Subsequent refinements included greater sinuosity and channel depth, pool/riffie construction with stone weirs, and buried alder and willow brush projecting from the bank. The reconstructed stream and floodplain have remained stable for five years, but have not been re-tested by a another large flood. The willow/alder riparian plant community is naturally revegetating on the new floodplains, but vigorous willows which sprouted from branches in brush bars and banks still provide the erosion protection.