Conservation status of freshwater gastropods of Canada and the United States

Science.gov (United States)

Johnson, Paul D.; Bogan, Arthur E.; Brown, Kenneth M.; Burkhead, Noel M.; Cordeiro, James R.; Garner, Jeffrey T.; Hartfield, Paul D.; Lepitzki, Dwayne A.; Mackie, Gerry L.; Pip, Eva; Tarpley, Thomas A.; Tiemann, Jeremy S.; Whelan, Nathan V.; Strong, Ellen E.

2013-01-01

This is the first American Fisheries Society conservation assessment of freshwater gastropods (snails) from Canada and the United States by the Gastropod Subcommittee (Endangered Species Committee). This review covers 703 species representing 16 families and 93 genera, of which 67 species are considered extinct, or possibly extinct, 278 are endangered, 102 are threatened, 73 are vulnerable, 157 are currently stable, and 26 species have uncertain taxonomic status. Of the entire fauna, 74% of gastropods are imperiled (vulnerable, threatened, endangered) or extinct, which exceeds imperilment levels in fishes (39%) and crayfishes (48%) but is similar to that of mussels (72%). Comparison of modern to background extinction rates reveals that gastropods have the highest modern extinction rate yet observed, 9,539 times greater than background rates. Gastropods are highly susceptible to habitat loss and degradation, particularly narrow endemics restricted to a single spring or short stream reaches. Compilation of this review was hampered by a paucity of current distributional information and taxonomic uncertainties. Although research on several fronts including basic biology, physiology, conservation strategies, life history, and ecology are needed, systematics and curation of museum collections and databases coupled with comprehensive status surveys (geographic limits, threat identification) are priorities.

Review of intersex in gastropods and other molluscs

DEFF Research Database (Denmark)

Strand, Jakob

Various studies have demonstrated that the presence of imposex, i.e. an imposition of a penis and/or a vas deferens in addition to the normal reproductive tracts in females of gonochoristics prosobranch gastropod species, is a common phenomenon in the marine environment today. However, also other....... This includes examples like transformation of the reproductive and genital tracts in gastropods and cephalopods, spermatogenesis in the female ovary and oocyte development in male testis (ovo-testis).  ......Various studies have demonstrated that the presence of imposex, i.e. an imposition of a penis and/or a vas deferens in addition to the normal reproductive tracts in females of gonochoristics prosobranch gastropod species, is a common phenomenon in the marine environment today. However, also other...... signs of endocrine disruption causing sex reversal, characterized as intersex, have been reported for marine molluscs. Intersex can more generally be defined as disturbance of the phenotypic sex characters and different types of intersex have been recorded for both female and male molluscs...

Snails and their trails: the multiple functions of trail-following in gastropods.

Science.gov (United States)

Ng, Terence P T; Saltin, Sara H; Davies, Mark S; Johannesson, Kerstin; Stafford, Richard; Williams, Gray A

2013-08-01

Snails are highly unusual among multicellular animals in that they move on a layer of costly mucus, leaving behind a trail that can be followed and utilized for various purposes by themselves or by other animals. Here we review more than 40 years of experimental and theoretical research to try to understand the ecological and evolutionary rationales for trail-following in gastropods. Data from over 30 genera are currently available, representing a broad taxonomic range living in both aquatic and terrestrial environments. The emerging picture is that the production of mucus trails, which initially was an adaptation to facilitate locomotion and/or habitat extension, has evolved to facilitate a multitude of additional functions. Trail-following supports homing behaviours, and provides simple mechanisms for self-organisation in groups of snails, promoting aggregation and thus relieving desiccation and predation pressures. In gastropods that copulate, trail-following is an important component in mate-searching, either as an alternative, or in addition to the release of water- or air-borne pheromones. In some species, this includes a capacity of males not only to identify trails of conspecifics but also to discriminate between trails laid by females and males. Notably, trail discrimination seems important as a pre-zygotic barrier to mating in some snail species. As production of a mucus trail is the most costly component of snail locomotion, it is also tempting to speculate that evolution has given rise to various ways to compensate for energy losses. Some snails, for example, increase energy intake by eating particles attached to the mucus of trails that they follow, whereas others save energy through reducing the production of their own mucus by moving over previously laid mucus trails. Trail-following to locate a prey item or a mate is also a way to save energy. While the rationale for trail-following in many cases appears clear, the basic mechanisms of trail

Changes in the reproductive system of the snail Helix aspersa caused by mucus from the love dart

NARCIS (Netherlands)

Koene, J M; Chase, R.

The function of the love dart in certain species of terrestrial snails is unknown. In Helix aspersa, the dart is a sharp calcareous structure that is used to pierce the partner's skin during courtship. When expelled, the dart is covered with a thick mucus. The hypothesis tested here is that the

Triple Helix going abroad?

DEFF Research Database (Denmark)

Sørensen, Olav Jull; Hu, Yimei

2014-01-01

The aim of the article is to explore to what extent the Tripple helix is being internationalized. Each of the helixes have their own internationalization rationale but the article show by small example that the helix itself is being internationalized and integrated with the host country tripple h...

Changes in habitat complexity negatively affect diverse gastropod assemblages in coralline algal turf.

Science.gov (United States)

Kelaher, B P

2003-05-01

The physical structure of a habitat generally has a strong influence on the diversity and abundance of associated organisms. I investigated the role of coralline algal turf structure in determining spatial variation of gastropod assemblages at different tidal heights of a rocky shore near Sydney, Australia. The structural characteristics of algal turf tested were frond density (or structural complexity) and frond length (the vertical scale over which structural complexity was measured). This definition of structural complexity assumes that complexity of the habitat increases with increasing frond density. While frond length was unrelated to gastropod community structure, I found significant correlations between density of fronds and multivariate and univariate measures of gastropod assemblages, indicating the importance of structural complexity. In contrast to previous studies, here there were negative relationships between the density of fronds and the richness and abundance of gastropods. Artificial habitat mimics were used to manipulate the density of fronds to test the hypothesis that increasing algal structural complexity decreases the richness and abundance of gastropods. As predicted, there were significantly more species of gastropods in loosely packed than in tightly packed turf at both low- and mid-shore levels. Despite large differences between gastropod assemblages at different tidal heights, the direction and magnitude of these negative effects were similar at low- and mid-shore levels and, therefore, relatively independent of local environmental conditions. These novel results extend our previous understanding of the ecological effects of habitat structure because they demonstrate possible limitations of commonly used definitions of structural complexity, as well as distinct upper thresholds in the relationship between structural complexity and faunal species richness.

Fauna of gastropod molluscs in the Curonian Lagoon littoral biotopes (Baltic Sea, Kaliningrad region, Russia

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Dmitry Filippenko

2011-12-01

Full Text Available A survey of the gastropod mollusc fauna in the coastal waters of the southern part of the Curonian Lagoon (Kaliningrad region, Russia were carried out. Study revealed 34 aquatic gastropods representing 30% of Prosobranchia and 70% of Pulmonata. Obtained data showed higher mollusc diversity in the littoral biotopes in comparison with open areas of the Lagoon. The fauna is represented by a typical Central European species complex of freshwater gastropods. The reed zone along the coastline in the Lagoon functions as a barrier and provides shallow water habitats with slow moving and warmer water, where maximum gastropod species concentrate.

Cesium-134 assimilation and retention in the landsnail Helix aspersa Muller 1974. Its potential usefulness as bioindicator for radioactive contamination

International Nuclear Information System (INIS)

Alfonso, L.A.; Carvalho, F.P.

1986-01-01

Cesium-134 retention was experimentally studied on two groups (n=20 in each) of the land-snail Helix aspersa, labelled either through ingestion of labelled food or the radionuclide injection into the foot muscle. Cesium elimination was found to be not dependent from the labelling technique used. The mean biological half-life for Cs retention in both Helix groups was 53.6+- 0.8 d for the largest retention component, accounting for 0.88 of the initally absorbed Cs. Another experiment runned on a similar size Helix group allowed the gravimetric determination of food ingestion rate (8.8 mg/ g/day) and food assimilation efficiency (0.70+-0.20). Predictive modelling of Cs accumulation by Helix indicates a relatively high bioaccumulation potential in this species. This fact, together with the long biological half-life found for Cs retention, indicate that land snails could be used as suitable bioindicators for radioactive pollution in restrict terrestrial areas. (author)

The "island rule" and deep-sea gastropods: re-examining the evidence.

Directory of Open Access Journals (Sweden)

John J Welch

2010-01-01

Full Text Available One of the most intriguing patterns in mammalian biogeography is the "island rule", which states that colonising species have a tendency to converge in body size, with larger species evolving decreased sizes and smaller species increased sizes. It has recently been suggested that an analogous pattern holds for the colonisation of the deep-sea benthos by marine Gastropoda. In particular, a pioneering study showed that gastropods from the Western Atlantic showed the same graded trend from dwarfism to gigantism that is evident in island endemic mammals. However, subsequent to the publication of the gastropod study, the standard tests of the island rule have been shown to yield false positives at a very high rate, leaving the result open to doubt.The evolution of gastropod body size in the deep sea is reexamined. Using an extended and updated data set, and improved statistical methods, it is shown that some results of the previous study may have been artifactual, but that its central conclusion is robust. It is further shown that the effect is not restricted to a single gastropod clade, that its strength increases markedly with depth, but that it applies even in the mesopelagic zone.The replication of the island rule in a distant taxonomic group and a partially analogous ecological situation could help to uncover the causes of the patterns observed--which are currently much disputed. The gastropod pattern is evident at intermediate depths, and so cannot be attributed to the unique features of abyssal ecology.

Chemical cues released by an alien invasive aquatic gastropod drive its invasion success.

Directory of Open Access Journals (Sweden)

Jacqueline L Raw

Full Text Available BACKGROUND: Chemical cues provide aquatic organisms with sensory information that guides behavioural responses and thus interactions among themselves, each other and the environment. Chemical cues are considered important for predator avoidance, foraging, larval settlement and broadcast spawning in aquatic environments. However, the significance of their role as drivers of direct interactions between heterospecifics has been largely overlooked. METHODOLOGY/PRINCIPAL FINDINGS: A video camera and a demarcated arena were used in situ to record behavioural responses of three native gastropod species, Assiminea cf. capensis, Melanoides tuberculata and Coriandria durbanensis, exposed to treatments representing chemical cues released by a non-native invasive gastropod, Tarebia granifera. The responses were measured quantitatively as displacement and orientation of movement at locations in St Lucia Estuary, within the iSimangaliso Wetland Park, a UNESCO World Heritage Site on the east coast of South Africa. All native gastropods exhibited a negative taxis response to chemical cues released by T. granifera, while T. granifera individuals responded randomly to conspecifics. Displacement was measured relative to the source of the extract, the number of steps taken were determined with path analysis and orientation was determined from the mean (±95% CIs turning angles, with significant negative turning angles representing negative taxis. Responses to treatments corresponding to the environment and conspecifics were random and undirected, indicating kinesis. CONCLUSION/SIGNIFICANCE: This study presents evidence for interactions driven by chemical cues between a non-native invasive gastropod and several gastropods native to South Africa. The results indicate that chemical cues can facilitate invasion success as the behavioural response of native gastropods is to move away allowing additional food and space resources to become available to T. granifera.

Chemical cues released by an alien invasive aquatic gastropod drive its invasion success.

Science.gov (United States)

Raw, Jacqueline L; Miranda, Nelson A F; Perissinotto, Renzo

2013-01-01

Chemical cues provide aquatic organisms with sensory information that guides behavioural responses and thus interactions among themselves, each other and the environment. Chemical cues are considered important for predator avoidance, foraging, larval settlement and broadcast spawning in aquatic environments. However, the significance of their role as drivers of direct interactions between heterospecifics has been largely overlooked. A video camera and a demarcated arena were used in situ to record behavioural responses of three native gastropod species, Assiminea cf. capensis, Melanoides tuberculata and Coriandria durbanensis, exposed to treatments representing chemical cues released by a non-native invasive gastropod, Tarebia granifera. The responses were measured quantitatively as displacement and orientation of movement at locations in St Lucia Estuary, within the iSimangaliso Wetland Park, a UNESCO World Heritage Site on the east coast of South Africa. All native gastropods exhibited a negative taxis response to chemical cues released by T. granifera, while T. granifera individuals responded randomly to conspecifics. Displacement was measured relative to the source of the extract, the number of steps taken were determined with path analysis and orientation was determined from the mean (±95% CIs) turning angles, with significant negative turning angles representing negative taxis. Responses to treatments corresponding to the environment and conspecifics were random and undirected, indicating kinesis. This study presents evidence for interactions driven by chemical cues between a non-native invasive gastropod and several gastropods native to South Africa. The results indicate that chemical cues can facilitate invasion success as the behavioural response of native gastropods is to move away allowing additional food and space resources to become available to T. granifera.

Large-scale spatial distribution patterns of gastropod assemblages in rocky shores.

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Patricia Miloslavich

Full Text Available Gastropod assemblages from nearshore rocky habitats were studied over large spatial scales to (1 describe broad-scale patterns in assemblage composition, including patterns by feeding modes, (2 identify latitudinal pattern of biodiversity, i.e., richness and abundance of gastropods and/or regional hotspots, and (3 identify potential environmental and anthropogenic drivers of these assemblages. Gastropods were sampled from 45 sites distributed within 12 Large Marine Ecosystem regions (LME following the NaGISA (Natural Geography in Shore Areas standard protocol (www.nagisa.coml.org. A total of 393 gastropod taxa from 87 families were collected. Eight of these families (9.2% appeared in four or more different LMEs. Among these, the Littorinidae was the most widely distributed (8 LMEs followed by the Trochidae and the Columbellidae (6 LMEs. In all regions, assemblages were dominated by few species, the most diverse and abundant of which were herbivores. No latitudinal gradients were evident in relation to species richness or densities among sampling sites. Highest diversity was found in the Mediterranean and in the Gulf of Alaska, while highest densities were found at different latitudes and represented by few species within one genus (e.g. Afrolittorina in the Agulhas Current, Littorina in the Scotian Shelf, and Lacuna in the Gulf of Alaska. No significant correlation was found between species composition and environmental variables (r≤0.355, p>0.05. Contributing variables to this low correlation included invasive species, inorganic pollution, SST anomalies, and chlorophyll-a anomalies. Despite data limitations in this study which restrict conclusions in a global context, this work represents the first effort to sample gastropod biodiversity on rocky shores using a standardized protocol across a wide scale. Our results will generate more work to build global databases allowing for large-scale diversity comparisons of rocky intertidal assemblages.

Multiple helix ecosystems for sustainable competitiveness

CERN Document Server

Ferreira, João; Farinha, Luís; Fernandes, Nuno

2016-01-01

This book discusses the main issues, challenges, opportunities, and trends involving the interactions between academia, industry, government and society. Specifically, it aims to explore how these interactions enhance the ways in which companies deliver products and services in order to achieve sustainable competitiveness in the marketplace. Sustainable competitiveness has been widely discussed by academics and practitioners, considering the importance of protecting the environment while sustaining the economic goals of organizations. The Quintuple Helix innovation model is a framework for facilitating knowledge, innovation and sustainable competitive advantage. It embeds the Triple and the Quadruple Helix models by adding a fifth helix, the “natural environment.” The Triple Helix model focuses on the university-industry-government triad, while the Quadruple adds civil society (the media- and culture-driven public) as a fourth helix. The Quintuple Helix model facilitates research, public policy, and pract...

Generating structured light with phase helix and intensity helix using reflection-enhanced plasmonic metasurface at 2 μm

Science.gov (United States)

Zhao, Yifan; Du, Jing; Zhang, Jinrun; Shen, Li; Wang, Jian

2018-04-01

Mid-infrared (2-20 μm) light has been attracting great attention in many areas of science and technology. Beyond the extended wavelength range from visible and near-infrared to mid-infrared, shaping spatial structures may add opportunities to grooming applications of mid-infrared photonics. Here, we design and fabricate a reflection-enhanced plasmonic metasurface and demonstrate efficient generation of structured light with the phase helix and intensity helix at 2 μm. This work includes two distinct aspects. First, structured light (phase helix, intensity helix) generation at 2 μm, which is far beyond the ability of conventional spatial light modulators, is enabled by the metasurface with sub-wavelength engineered structures. Second, the self-referenced intensity helix against environmental noise is generated without using a spatially separated light. The demonstrations may open up advanced perspectives to structured light applications at 2 μm, such as phase helix for communications and non-communications (imaging, sensing) and intensity helix for enhanced microscopy and advanced metrology.

Impacts of Near-Future Ocean Acidification and Warming on the Shell Mechanical and Geochemical Properties of Gastropods from Intertidal to Subtidal Zones.

Science.gov (United States)

Leung, Jonathan Y S; Connell, Sean D; Nagelkerken, Ivan; Russell, Bayden D

2017-11-07

Many marine organisms produce calcareous shells as the key structure for defense, but the functionality of shells may be compromised by ocean acidification and warming. Nevertheless, calcifying organisms may adaptively modify their shell properties in response to these impacts. Here, we examined how reduced pH and elevated temperature affect shell mechanical and geochemical properties of common grazing gastropods from intertidal to subtidal zones. Given the greater environmental fluctuations in the intertidal zone, we hypothesized that intertidal gastropods would exhibit more plastic responses in shell properties than subtidal gastropods. Overall, three out of five subtidal gastropods produced softer shells at elevated temperature, while intertidal gastropods maintained their shell hardness at both elevated pCO 2 (i.e., reduced pH) and temperature. Regardless of pH and temperature, degree of crystallization was maintained (except one subtidal gastropod) and carbonate polymorph remained unchanged in all tested species. One intertidal gastropod produced less soluble shells (e.g., higher calcite/aragonite) in response to reduced pH. In contrast, subtidal gastropods produced only aragonite which has higher solubility than calcite. Overall, subtidal gastropods are expected to be more susceptible than intertidal gastropods to shell dissolution and physical damage under future seawater conditions. The increased vulnerability to shell dissolution and predation could have serious repercussions for their survival and ecological contributions in the future subtidal environment.

A Classification of Basic Helix-Loop-Helix Transcription Factors of Soybean

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Karen A. Hudson

2015-01-01

Full Text Available The complete genome sequence of soybean allows an unprecedented opportunity for the discovery of the genes controlling important traits. In particular, the potential functions of regulatory genes are a priority for analysis. The basic helix-loop-helix (bHLH family of transcription factors is known to be involved in controlling a wide range of systems critical for crop adaptation and quality, including photosynthesis, light signalling, pigment biosynthesis, and seed pod development. Using a hidden Markov model search algorithm, 319 genes with basic helix-loop-helix transcription factor domains were identified within the soybean genome sequence. These were classified with respect to their predicted DNA binding potential, intron/exon structure, and the phylogeny of the bHLH domain. Evidence is presented that the vast majority (281 of these 319 soybean bHLH genes are expressed at the mRNA level. Of these soybean bHLH genes, 67% were found to exist in two or more homeologous copies. This dataset provides a framework for future studies on bHLH gene function in soybean. The challenge for future research remains to define functions for the bHLH factors encoded in the soybean genome, which may allow greater flexibility for genetic selection of growth and environmental adaptation in this widely grown crop.

Origin and Diversification of Basic-Helix-Loop-Helix Proteins in Plants

OpenAIRE

Pires, Nuno; Dolan, Liam

2009-01-01

Basic helix-loop-helix (bHLH) proteins are a class of transcription factors found throughout eukaryotic organisms. Classification of the complete sets of bHLH proteins in the sequenced genomes of Arabidopsis thaliana and Oryza sativa (rice) has defined the diversity of these proteins among flowering plants. However, the evolutionary relationships of different plant bHLH groups and the diversity of bHLH proteins in more ancestral groups of plants are currently unknown. In this study, we use wh...

Recognition and Binding of a Helix-Loop-Helix Peptide to Carbonic Anhydrase Occurs via Partly Folded Intermediate Structures

Science.gov (United States)

Lignell, Martin; Becker, Hans-Christian

2010-01-01

Abstract We have studied the association of a helix-loop-helix peptide scaffold carrying a benzenesulfonamide ligand to carbonic anhydrase using steady-state and time-resolved fluorescence spectroscopy. The helix-loop-helix peptide, developed for biosensing applications, is labeled with the fluorescent probe dansyl, which serves as a polarity-sensitive reporter of the binding event. Using maximum entropy analysis of the fluorescence lifetime of dansyl at 1:1 stoichiometry reveals three characteristic fluorescence lifetime groups, interpreted as differently interacting peptide/protein structures. We characterize these peptide/protein complexes as mostly bound but unfolded, bound and partly folded, and strongly bound and folded. Furthermore, analysis of the fluorescence anisotropy decay resulted in three different dansyl rotational correlation times, namely 0.18, 1.2, and 23 ns. Using the amplitudes of these times, we can correlate the lifetime groups with the corresponding fluorescence anisotropy component. The 23-ns rotational correlation time, which appears with the same amplitude as a 17-ns fluorescence lifetime, shows that the dansyl fluorophore follows the rotational diffusion of carbonic anhydrase when it is a part of the folded peptide/protein complex. A partly folded and partly hydrated interfacial structure is manifested in an 8-ns dansyl fluorescence lifetime and a 1.2-ns rotational correlation time. This structure, we believe, is similar to a molten-globule-like interfacial structure, which allows segmental movement and has a higher degree of solvent exposure of dansyl. Indirect excitation of dansyl on the helix-loop-helix peptide through Förster energy transfer from one or several tryptophans in the carbonic anhydrase shows that the helix-loop-helix scaffold binds to a tryptophan-rich domain of the carbonic anhydrase. We conclude that binding of the peptide to carbonic anhydrase involves a transition from a disordered to an ordered structure of the

Chirality-specific lift forces of helix under shear flows: Helix perpendicular to shear plane.

Science.gov (United States)

Zhang, Qi-Yi

2017-02-01

Chiral objects in shear flow experience a chirality-specific lift force. Shear flows past helices in a low Reynolds number regime were studied using slender-body theory. The chirality-specific lift forces in the vorticity direction experienced by helices are dominated by a set of helix geometry parameters: helix radius, pitch length, number of turns, and helix phase angle. Its analytical formula is given. The chirality-specific forces are the physical reasons for the chiral separation of helices in shear flow. Our results are well supported by the latest experimental observations. © 2016 Wiley Periodicals, Inc.

Reconsolidation of a Context Long-Term Memory in the Terrestrial Snail Requires Protein Synthesis

Science.gov (United States)

Gainutdinova, Tatiana H.; Tagirova, Rosa R.; Ismailova, Asja I.; Muranova, Lyudmila N.; Samarova, Elena I.; Gainutdinov, Khalil L.; Balaban, Pavel M.

2005-01-01

We investigated the influence of the protein synthesis blocker anisomycin on contextual memory in the terrestrial snail "Helix." Prior to the training session, the behavioral responses in two contexts were similar. Two days after a session of electric shocks (5 d) in one context only, the context conditioning was observed as the significant…

Helix-Hopes on Finite Hyperfields

Directory of Open Access Journals (Sweden)

Thomas Vougiouklis

2016-12-01

Full Text Available Hyperstructure theory can overcome restrictions which ordinary algebraic structures have. A hyperproduct on non-square ordinary matrices can be defined by using the so called helix-hyperoperations. We study the helix-hyperstructures on the representations using ordinary fields. The related theory can be faced by defining the hyperproduct on the set of non square matrices. The main tools of the Hyperstructure Theory are the fundamental relations which connect the largest class of hyperstructures, the Hv-structures, with the corresponding classical ones. We focus on finite dimensional helix-hyperstructures and on small Hv-fields, as well.

Trophic discrimination factor and the significance of mangrove litter to benthic detritivorous gastropod, Ellobium aurisjudae (Linnaeus)

Science.gov (United States)

Teoh, Hong Wooi; Sasekumar, A.; Ismail, Mohamad Hanif; Chong, Ving Ching

2018-01-01

In stable isotope analysis, the estimation of proportional contribution of carbon and nitrogen from mangrove to benthic invertebrates requires knowledge of the food-consumer trophic discrimination factor (Δ δ13C and Δ δ15N). This study tested the hypothesis that the mangrove gastropod Ellobium aurisjudae can assimilate low quality refractory mangrove litter and aimed to determine the trophic discrimination values (TDV) of C and N isotopes between gastropod and the mangrove producer. The mean Δ δ13C for gastropods fed senescent leaves of the mangrove Bruguiera parviflora (Roxb) Wight & Arn and decomposing mangrove (unknown species from the same site) wood were estimated at 5.3 ± 0.3‰ and 3.2 ± 0.5‰ respectively, whereas for Δ δ15N, these values were 4.2 ± 0.2‰ and 6.0 ± 0.2‰ respectively. The gastropod assimilated refractory carbon from mangrove leaf and wood litter with 49% and 18% efficiency respectively. Rearing experiment of gastropods (n = 25) fed only mangrove wood litter over 5months in the laboratory, showed mean weight increments of 14.8-74.4% depending on the initial animal weight. Significant deviation of the TDVs for E. aurisjudae from the generalized discrimination values for herbivory underscores the need to use specific TDV for the detritivory link.

Evidence for a possible role for nitric oxide in the modulation of heart activity in Achatina fulica and Helix aspersa.

Science.gov (United States)

White, A R; Curtis, S A; Walker, R J

2004-02-01

The effects of nitric oxide (NO) donors, S-nitroso-N-acetylpenicillamine, S-nitroso-l-glutathione, sodium nitroprusside and sodium nitrite were investigated on the activity of the isolated hearts of Achatina fulica and Helix aspersa. NO donors inhibited heart activity in a concentration-dependent manner. The only exception was sodium nitroprusside, which excited H. aspersa heart. The inhibitory effects of these NO donors were reduced by the NO scavenger, methylene blue, the guanylyl cyclase inhibitor, 1H-(1,2,4) Oxadiazolo(4,3-a)quinoxalin-1-one (ODQ), and potentiated by 8-Br-cGMP and the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). Acetylcholine also inhibited the heart activity, and this inhibition was reduced by methylene blue and ODQ. Positive NADPH-diaphorase staining was located in the outer pericardial layer of the heart of A. fulica. The present results provide evidence that NO may modulate the activity of gastropod hearts, and this modulation may modify the inhibitory action of acetylcholine on heart activity.

Gibberellin-regulated gene in the basal region of rice leaf sheath encodes basic helix-loop-helix transcription factor.

Science.gov (United States)

Komatsu, Setsuko; Takasaki, Hironori

2009-07-01

Genes regulated by gibberellin (GA) during leaf sheath elongation in rice seedlings were identified using the transcriptome approach. mRNA from the basal regions of leaf sheaths treated with GA3 was analyzed by high-coverage gene expression profiling. 33,004 peaks were detected, and 30 transcripts showed significant changes in the presence of GA3. Among these, basic helix-loop-helix transcription factor (AK073385) was significantly upregulated. Quantitative PCR analysis confirmed that expression of AK073385 was controlled by GA3 in a time- and dose-dependent manner. Basic helix-loop-helix transcription factor (AK073385) is therefore involved in the regulation of gene expression by GA3.

Bioaccumulation of 210Po in common gastropod and bivalve species from the northern Gulf.

Science.gov (United States)

Uddin, S; Bebhehani, M

2014-06-01

This study sets the baseline for the concentration of the natural-series radionuclide polonium-210 in two species of gastropods and four species of bivalves that are common to the Northern Arabian/Persian Gulf. (210)Po is primarily absorbed from water and via ingestion of detrital material by gastropoda and bivalves. This concentrated (210)Po can then be passed along to the next trophic level of the marine food web. The lowest (210)Po concentration was measured in the gastropod Stomatella auricular (10.36-12.39Bq kg(-1)dry) and the highest in the bivalve Marica marmorata (193.51-215.60Bq kg(-1)dry). The measured concentration factor for these molluscs in the northern Gulf varied between 4.8 and 115×10(3), values very similar to the IAEA recommended value for bivalves and gastropods of 2×10(4). Copyright © 2014 Elsevier Inc. All rights reserved.

Double-helix stellarator

International Nuclear Information System (INIS)

Moroz, P.E.

1997-09-01

A new stellarator configuration, the Double-Helix Stellarator (DHS), is introduced. This novel configuration features a double-helix center post as the only helical element of the stellarator coil system. The DHS configuration has many unique characteristics. One of them is the extreme low plasma aspect ratio, A ∼ 1--1.2. Other advantages include a high enclosed volume, appreciable rotational transform, and a possibility of extreme-high-β MHD equilibria. Moreover, the DHS features improved transport characteristics caused by the absence of the magnetic field ripple on the outboard of the torus. Compactness, simplicity and modularity of the coil system add to the DHS advantages for fusion applications

The swimming of a perfect deforming helix

Science.gov (United States)

Koens, Lyndon; Zhang, Hang; Mourran, Ahmed; Lauga, Eric

2017-11-01

Many bacteria rotate helical flagellar filaments in order to swim. When at rest or rotated counter-clockwise these flagella are left handed helices but they undergo polymorphic transformations to right-handed helices when the motor is reversed. These helical deformations themselves can generate motion, with for example Rhodobacter sphaeroides using the polymorphic transformation of the flagellum to generate rotation, or Spiroplasma propagating a change of helix handedness across its body's length to generate forward motion. Recent experiments reported on an artificial helical microswimmer generating motion without a propagating change in handedness. Made of a temperature sensitive gel, these swimmers moved by changing the dimensions of the helix in a non-reciprocal way. Inspired by these results and helix's ubiquitous presence in the bacterial world, we investigate how a deforming helix moves within a viscous fluid. Maintaining a single handedness along its entire length, we discuss how a perfect deforming helix can create a non-reciprocal swimming stroke, identify its principle directions of motion, and calculate the swimming kinematics asymptotically.

Structure of gastropod communities at mangrove ecosystem in Lubuk Kertang village, West Berandan District, Langkat Regency, North Sumatera Province

Science.gov (United States)

Manullang, T.; Bakti, D.; Leidonald, R.

2018-02-01

Gastropod was one of the class from mollusca in mangrove ecosystem. Lubuk Kertang Village’s mangrove forest was been converted into tourist areas, agricultural land and settlements. The purpose of this study was to analyze the structure of gastropods at Avicennia lanata, Rhizophora apiculata and Sonneratia alba. This research was conducted at Lubuk Kertang Village in February-March 2017. Gastropod were collected in 1 m × 1 m transect in mangrove. Examples of biota were taken by using shovel, then the biota was inserted into a plastic bag sample, wrote date of sampling and identified. The results showed there were 15 species Gastropods, namely Achatina fulica, Cerithidea alata, Cerithidea cingulata, Cerithidea obtusa, Chicoreus capucinus, Cymatium pileare, Ellobium aurimisdae, Ellobium aurisjudae, Littoraria melanostoma, Littoraria scabra, Murex tribulus, Nerita balteata, Nerita planospira, Pugilina cochlidium, Stramonita gradata, Telescopium telescopium and Terebralia sulcata. Diversity index ranged 1.702 to 2.165 was in medium category, Similarity index ranged 0.676 to 0.799 was in low category and Dominance index ranged 0.142 to 0.282 that categorized was low. The highest gastropod density was 31 individuals/m2 in the Sonneratia alba. The conclusion of the research is the existing mangrove ecosystem in Lubuk Kertang Village in a stable state.

Gastropod diversity, distribution and abundance in habitats with and without anthropogenic disturbances in Lake Victoria, Kenya

DEFF Research Database (Denmark)

Lange, C. N.; Kristensen, Thomas K.; Madsen, Henry

2013-01-01

We investigated freshwater gastropod diversity, abundance and distribution in habitats with and without anthropogenic disturbance in two localities, Ndere in the Winam Gulf and Mbita Point, Lake Victoria, Kenya, from May 2002 to January 2004. A total of 133 984 gastropod specimens belonging to 15...... species were recorded, 14 from Mbita and 12 from Ndere. Two species, Ferrissia kavirondica and Cleopatra cridlandi, which were recorded only from undisturbed habitats, could be indicators of least disturbed habitats. Water chemistry did differ between fish landing sites and undisturbed habitats at some......, while other species may not tolerate these changes. In order to protect gastropod diversity and avoid dominance of intermediate hosts, such as B. choanomphala, a management plan for the use of these fish landing sites should be developed. This could include rules on how to dispose of fish remnants...

Transcriptome of the Antarctic brooding gastropod mollusc Margarella antarctica.

Science.gov (United States)

Clark, Melody S; Thorne, Michael A S

2015-12-01

454 RNA-Seq transcriptome data were generated from foot tissue of the Antarctic brooding gastropod mollusc Margarella antarctica. A total of 6195 contigs were assembled de novo, providing a useful resource for researchers with an interest in Antarctic marine species, phylogenetics and mollusc biology, especially shell production. Copyright © 2015 Elsevier B.V. All rights reserved.

Tributyltin bioaccumulation and toxic effects in freshwater gastropods Pomacea canaliculata after a chronic exposure: field and laboratory studies.

Science.gov (United States)

Martínez, María L; Piol, María N; Sbarbati Nudelman, Norma; Verrengia Guerrero, Noemí R

2017-07-01

Freshwater samples and gastropod mollusks (Pomacea canaliculata) were collected at 5 sampling stations located along the lower Río de la Plata basin, Argentina, to assess the extent of tributyltin (TBT) contamination. Determined data revealed the presence of TBT and some of its breakdown products (dibutyltin: DBT, and monobutyltin: MBT) in all freshwater samples and also in soft tissues of P. canaliculata gastropods. Chronic bioassays (6 months) were performed using female gastropods that had been reared under laboratory conditions and exposed to a similar TBT concentration than the value determined in freshwater samples (1 µg L -1 ). The aims of this study were to evaluate the extent of TBT accumulation, the tissue distribution, and the effects on selected biomarkers (activity of superoxide dismutasa: SOD, activity of catalase: CAT, levels of total glutathione: t-GSH, lipid peroxidation, and activity of acetylcholinesterase: AChE). Gonads presented the highest accumulation, followed by the cephalopedal region, albumin gland, and finally hepatopancreas. Both metabolites, DBT and MBT, were also found. All exposed female animals presented development of a penis reflecting the potential of TBT as an endocrine disrupting chemical for this gastropod species. Results on the selected biomarkers confirmed additional adverse effects induced by TBT. An increase in CAT activity and changes in t-GSH levels are indicative of alterations on the cellular redox status. The inhibition of AChE could reflect signs of neurotoxicity. Altogether, these results reveal a negative impact on the health of this gastropod population.

Comparative study on gill morphology of gastropods from Moreton Bay, Queensland

NARCIS (Netherlands)

Eertman, R.H.M.

1996-01-01

This paper reports the gill morphology of seven common gastropods from Moreton Bay, southeastern Queensland, to test the level of difference in gill structure between major taxa. The investigated species include representatives of the clades Patellogastropoda, Neritimorpha and Vetigastropda as well

Effect of pollution on diversity of marine gastropods and its role in trophic structure at Nasese Shore, Suva, Fiji Islands

Directory of Open Access Journals (Sweden)

Dissanayake Mudiyanselage Suratissa

2017-06-01

Full Text Available Ocean supplies a significant amount of food to human population. However, marine ecosystem is under a threat due to the increasing marine pollution. Fiji Islands, located in South Pacific sea, are experiencing such a threat. Therefore, this study aims to determine the effects of pollution on the diversity of marine gastropods in Nasese Shore, Suva, Fiji Islands. A detailed opportunistic survey was conducted; 85 species of marine gastropods molluscas were recorded belonging to 29 families in four different habitats (Habitat 1, Habitat 2, Habitat 3 and Habitat 4 at Nasese Shore during April–September 2014. Compared with Habitat 4, all three other habitats were polluted by frequently added sewages and domestic effluents via artificial and natural creeks to the coastal area. Therefore, diversity and abundance of the gastropods were significantly lower in those three habitats. Furthermore, a higher human consumption rate for some of the gastropods was observed.

Labelling and Marketing of Bivalve and Gastropod Molluscs Retailed in Sardinia, Italy Between 2009 and 2013.

Science.gov (United States)

Meloni, Domenico

2015-05-28

The aim of the present survey was to investigate the correct enforcement of the Community rules on the labelling and marketing of bivalve and gastropod molluscs retailed in Sardinia, Italy between 2009 and 2013. A total of 1500 packages and labels for live bivalve and gastropod molluscs were considered. A total of 375 labels (25%) presented non-compliance concerning the wrong trade name and additional wrong or missing information. The highest percentage of anomalous labels has been detected in small-scale retail shops (35%) and open-air markets (25%) compared with the big retailing chains (20%). The 5% of packages were not in compliance with the European Community rules on packaging of bivalve and gastropod molluscs. The high percentage of non-compliance with the European regulations on labelling results is a strong limitation for the consumers and highlights the need to improve the control system about labelling of seafood products.

Designing cooperatively folded abiotic uni- and multimolecular helix bundles

Science.gov (United States)

de, Soumen; Chi, Bo; Granier, Thierry; Qi, Ting; Maurizot, Victor; Huc, Ivan

2018-01-01

Abiotic foldamers, that is foldamers that have backbones chemically remote from peptidic and nucleotidic skeletons, may give access to shapes and functions different to those of peptides and nucleotides. However, design methodologies towards abiotic tertiary and quaternary structures are yet to be developed. Here we report rationally designed interactional patterns to guide the folding and assembly of abiotic helix bundles. Computational design facilitated the introduction of hydrogen-bonding functionalities at defined locations on the aromatic amide backbones that promote cooperative folding into helix-turn-helix motifs in organic solvents. The hydrogen-bond-directed aggregation of helices not linked by a turn unit produced several thermodynamically and kinetically stable homochiral dimeric and trimeric bundles with structures that are distinct from the designed helix-turn-helix. Relative helix orientation within the bundles may be changed from parallel to tilted on subtle solvent variations. Altogether, these results prefigure the richness and uniqueness of abiotic tertiary structure behaviour.

5-Bromo-2'-deoxyuridine impairs long-term food aversion memory in edible snail.

Science.gov (United States)

Efimova, O I; Anokhin, K V

2012-09-01

We studied the involvement of DNA synthesis into molecular mechanisms of long-term memory. Nucleoside analogue 5-bromo-2'-deoxyuridine (BrdU) is known to incorporate into synthesizing DNA and prevent subsequent DNA replication from this region. To investigate the effect of BrdU administration on long-term memory, terrestrial gastropods edible snails Helix lucorum were trained in the food aversion paradigm. Single-session training (carrot presentation combined with application of 10% quinine solution, three carrot presentations with 10-min intervals) resulted in the formation of long-term memory that persisted for at least 45° days. BrdU administration (250 mg/kg) 30 min before training impaired long-term memory tested 24 h later. Immunohistochemical study revealed BrdU incorporation in the nuclei of identified neurons of defensive behavior.

Stable isotope evidence for dietary overlap between alien and native gastropods in coastal lakes of northern KwaZulu-Natal, South Africa.

Directory of Open Access Journals (Sweden)

Nelson A F Miranda

Full Text Available Tarebia granifera (Lamarck, 1822 is originally from South-East Asia, but has been introduced and become invasive in many tropical and subtropical parts of the world. In South Africa, T. granifera is rapidly invading an increasing number of coastal lakes and estuaries, often reaching very high population densities and dominating shallow water benthic invertebrate assemblages. An assessment of the feeding dynamics of T. granifera has raised questions about potential ecological impacts, specifically in terms of its dietary overlap with native gastropods.A stable isotope mixing model was used together with gut content analysis to estimate the diet of T. granifera and native gastropod populations in three different coastal lakes. Population density, available biomass of food and salinity were measured along transects placed over T. granifera patches. An index of isotopic (stable isotopes dietary overlap (IDO, % aided in interpreting interactions between gastropods. The diet of T. granifera was variable, including contributions from microphytobenthos, filamentous algae (Cladophora sp., detritus and sedimentary organic matter. IDO was significant (>60% between T. granifera and each of the following gastropods: Haminoea natalensis (Krauss, 1848, Bulinus natalensis (Küster, 1841 and Melanoides tuberculata (Müller, 1774. However, food did not appear to be limiting. Salinity influenced gastropod spatial overlap. Tarebia granifera may only displace native gastropods, such as Assiminea cf. ovata (Krauss, 1848, under salinity conditions below 20. Ecosystem-level impacts are also discussed.The generalist diet of T. granifera may certainly contribute to its successful establishment. However, although competition for resources may take place under certain salinity conditions and if food is limiting, there appear to be other mechanisms at work, through which T. granifera displaces native gastropods. Complementary stable isotope and gut content analysis can

Measurement of DNA integrity in marine gastropods as biomarker of genotoxicity

Digital Repository Service at National Institute of Oceanography (India)

Sarkar, A.; Vashistha, D.; Gupta, N.; Malik, K.; Gaitonde, D.C.S.

to identify the hot spot of pollution due to genotoxic compounds, the DNA damage was measured in terms of the loss of DNA integrity in marine gastropods due to the occurrence of DNA strand breaks following the technique of time dependent partially alkaline...

Labelling and marketing of bivalve and gastropod molluscs retailed in Sardinia, Italy between 2009 and 2013

Directory of Open Access Journals (Sweden)

Domenico Meloni

2015-06-01

Full Text Available The aim of the present survey was to investigate the correct enforcement of the Community rules on the labelling and marketing of bivalve and gastropod molluscs retailed in Sardinia, Italy between 2009 and 2013. A total of 1500 packages and labels for live bivalve and gastropod molluscs were considered. A total of 375 labels (25% presented non-compliance concerning the wrong trade name and additional wrong or missing information. The highest percentage of anomalous labels has been detected in small-scale retail shops (35% and open-air markets (25% compared with the big retailing chains (20%. The 5% of packages were not in compliance with the European Community rules on packaging of bivalve and gastropod molluscs. The high percentage of non-compliance with the European regulations on labelling results is a strong limitation for the consumers and highlights the need to improve the control system about labelling of seafood products.

Helix probe areas for the utilization of geothermal power. A practical example; Helix-Sondenfelder zur Nutzung von Erdwaerme. Ein Praxisbeispiel

Energy Technology Data Exchange (ETDEWEB)

Kuebert, Markus; Walker-Hertkorn, Simone [tewag Technologie - Erdwaermeanlagen - Umweltschutz GmbH, Starzach (Germany); Tietz, Jan [REHAU AG und Co., Erlangen-Eltersdorf (Germany); Riepold, Markus; Gloeckl, Andreas [MR Tiefbau GmbH, Brunnen (Germany)

2013-02-01

Thanks to their spiral shape so-called helix probes with a tube length of 40 meter have a height of only three meter: A lot of heat exchange area in a small space. Thus, helix probes are an ideal solution for the utilization of geothermal energy at places at which one cannot drill deeply due to geothermal reasons. Under this aspect, the contribution under consideration reports on the planning of a helix probe area being sustainably adapted to the user requirements for the new construction of a production facility.

Does Height to Width Ratio Correlate with Mean Volume in Gastropods?

Science.gov (United States)

Barriga, R.; Seixas, G.; Payne, J.

2012-12-01

Marine organisms' shell shape and size show important biological information. For example, shape and size can dictate how the organism ranges for food and escapes predation. Due to lack of data and analysis, the evolution of shell size in marine gastropods (snails) remains poorly known. In this study, I attempt to find the relationship between height to width ratio and mean volume. I collected height and width measurements from primary literature sources and calculated volume from these measurements. My results indicate that there was no correlation between height to width ratio and mean volume between 500 to 200 Ma, but there was a correlation between 200 Ma to present where there is a steady increase in both height to width ratio and mean volume. This means that shell shape was not an important factor at the beginning of gastropod evolution but after 200 Ma body size evolution was increasingly driven by the height to width ratio.

Gastropod shells: a dynamic resource that helps shape benthic community structure. [Calliactis tricolor; Pagurus pollicaris; Calappa flammea; Octopus joubini; Panulirus argus

Energy Technology Data Exchange (ETDEWEB)

McLean, R

1983-01-01

Empty gastropod shells are an important resource for many animals in shallow benthic marine communities. Shells provide shelter for hermit crabs, octopuses, and fishes, provide attachment substratum for hermit crab symbionts, and directly or indirectly modify hermit crab predation. Creation of an empty shell due to predation of one gastropod on another and acquisition of that shell by a hermit crab are two key events in the subsequent use of that shell. Shells of different gastropod species and the species of hermit crab acquiring them affect the symbiont complement that attaches to the shell, which in turn may affect future shell use by other symbionts. Certain shell types worn by the hermit crab, Pagurus pollicaris Say, are positively associated with the symbiotic sea anemone, Calliactis tricolor (Lesueur), which protects the hermit crab from predation by the crab, Calappa flammea (Herbst), and possibly from the octopus, Octopus joubini Robson. Shells of other species of gastropods are resistant to being crushed by the spiny lobster, Panulirus argus (Latreille). The inter- and intraspecific interactions centered on the gastropod shell are termed a ''habitat web.'' The potential of the shell to limit the size and distribution of animal populations demonstrates how this resource helps shape community structure.

Interactions between the mixotrophic dinoflagellate Takayama helix and common heterotrophic protists.

Science.gov (United States)

Ok, Jin Hee; Jeong, Hae Jin; Lim, An Suk; Lee, Kyung Ha

2017-09-01

The phototrophic dinoflagellate Takayama helix that is known to be harmful to abalone larvae has recently been revealed to be mixotrophic. Although mixotrophy elevates the growth rate of T. helix by 79%-185%, its absolute growth rate is still as low as 0.3d -1 . Thus, if the mortality rate of T. helix due to predation is high, this dinoflagellate may not easily prevail. To investigate potential effective protistan grazers on T. helix, feeding by diverse heterotrophic dinoflagellates such as engulfment-feeding Oxyrrhis marina, Gyrodinium dominans, Gyrodinium moestrupii, Polykrikos kofoidii, and Noctiluca scintillans, peduncle-feeding Aduncodinium glandula, Gyrodiniellum shiwhaense, Luciella masanensis, and Pfiesteria piscicida, pallium-feeding Oblea rotunda and Protoperidinium pellucidum, and the naked ciliates Pelagostrobilidium sp. (ca. 40μm in cell length) and Strombidinopsis sp. (ca. 150μm in cell length) on T. helix was explored. Among the tested heterotrophic protists, O. marina, G. dominans, G. moestrupii, A. glandula, L. masanensis, P. kofoidii, P. piscicida, and Strombidinopsis sp. were able to feed on T. helix. The growth rates of all these predators except Strombidinopsis sp. with T. helix prey were lower than those without the prey. The growth rate of Strombidinopsis sp. on T. helix was almost zero although the growth rate of Strombidinopsis sp. with T. helix prey was higher than those without the prey. Moreover, T. helix fed on O. marina and P. pellucidum and lysed the cells of P. kofoidii and G. shiwhaense. With increasing the concentrations of T. helix, the growth rates of O. marina and P. kofoidii decreased, but those of G. dominans and L. masanensis largely did not change. Therefore, reciprocal predation, lysis, no feeding, and the low ingestion rates of the common protists preying on T. helix may result in a low mortality rate due to predation, thereby compensating for this species' low growth rate. Copyright © 2017 Elsevier B.V. All rights

Government and Governance of Regional Triple Helix Interactions

Science.gov (United States)

Danson, Mike; Todeva, Emanuela

2016-01-01

This conceptual paper contributes to the discussion of the role of regional government and regional Triple Helix constellations driving economic development and growth within regional boundaries. The impact of regionalism and subsidiarity on regional Triple Helix constellations, and the questions of governmentality, governance and institutional…

A basic helix-loop-helix transcription factor, PhFBH4, regulates flower senescence by modulating ethylene biosynthesis pathway in petunia

Science.gov (United States)

The basic helix-loop-helix (bHLH) transcription factors (TFs) play important roles in regulating multiple biological processes in plants. However, there are few reports about the function of bHLHs in flower senescence. In this study, a bHLH TF, PhFBH4, was found to be dramatically upregulated during...

Double helix vortex breakdown in a turbulent swirling annular jet flow

Science.gov (United States)

Vanierschot, M.; Percin, M.; van Oudheusden, B. W.

2018-03-01

In this paper, we report on the structure and dynamics of double helix vortex breakdown in a turbulent annular swirling jet. Double helix breakdown has been reported previously for the laminar flow regime, but this structure has rarely been observed in turbulent flow. The flow field is investigated experimentally by means of time-resolved tomographic particle image velocimetry. Notwithstanding the axisymmetric nature of the time-averaged flow, analysis of the instantaneous three-dimensional (3D) vortical structures shows the existence of a vortex core along the central axis which breaks up into a double helix downstream. The winding sense of this double helix is opposite to the swirl direction (m =-2 ) and it is wrapped around a central vortex breakdown bubble. This structure is quite different from double helix breakdown found in laminar flows where the helix is formed in the wake of the bubble and not upstream. The double helix precesses around the central axis of the jet with a precessing frequency corresponding to a Strouhal number of 0.27.

An α-Helix-Mimicking 12,13-Helix: Designed α/β/γ-Foldamers as Selective Inhibitors of Protein-Protein Interactions.

Science.gov (United States)

Grison, Claire M; Miles, Jennifer A; Robin, Sylvie; Wilson, Andrew J; Aitken, David J

2016-09-05

A major current challenge in bioorganic chemistry is the identification of effective mimics of protein secondary structures that act as inhibitors of protein-protein interactions (PPIs). In this work, trans-2-aminocyclobutanecarboxylic acid (tACBC) was used as the key β-amino acid component in the design of α/β/γ-peptides to structurally mimic a native α-helix. Suitably functionalized α/β/γ-peptides assume an α-helix-mimicking 12,13-helix conformation in solution, exhibit enhanced proteolytic stability in comparison to the wild-type α-peptide parent sequence from which they are derived, and act as selective inhibitors of the p53/hDM2 interaction. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

IFITM3 requires an amphipathic helix for antiviral activity.

Science.gov (United States)

Chesarino, Nicholas M; Compton, Alex A; McMichael, Temet M; Kenney, Adam D; Zhang, Lizhi; Soewarna, Victoria; Davis, Matthew; Schwartz, Olivier; Yount, Jacob S

2017-10-01

Interferon-induced transmembrane protein 3 (IFITM3) is a cellular factor that blocks virus fusion with cell membranes. IFITM3 has been suggested to alter membrane curvature and fluidity, though its exact mechanism of action is unclear. Using a bioinformatic approach, we predict IFITM3 secondary structures and identify a highly conserved, short amphipathic helix within a hydrophobic region of IFITM3 previously thought to be a transmembrane domain. Consistent with the known ability of amphipathic helices to alter membrane properties, we show that this helix and its amphipathicity are required for the IFITM3-dependent inhibition of influenza virus, Zika virus, vesicular stomatitis virus, Ebola virus, and human immunodeficiency virus infections. The homologous amphipathic helix within IFITM1 is also required for the inhibition of infection, indicating that IFITM proteins possess a conserved mechanism of antiviral action. We further demonstrate that the amphipathic helix of IFITM3 is required to block influenza virus hemagglutinin-mediated membrane fusion. Overall, our results provide evidence that IFITM proteins utilize an amphipathic helix for inhibiting virus fusion. © 2017 The Authors.

Effect of Hedera helix on lung histopathology in chronic asthma.

Science.gov (United States)

Hocaoglu, Arzu Babayigit; Karaman, Ozkan; Erge, Duygu Olmez; Erbil, Guven; Yilmaz, Osman; Kivcak, Bijen; Bagriyanik, H Alper; Uzuner, Nevin

2012-12-01

Hedera helix is widely used to treat bronchial asthma for many years. However, effects of this herb on lung histopathology is still far from clear. We aimed to determine the effect of oral administration of Hedera helix on lung histopathology in a murine model of chronic asthma.BALB/c mice were divided into four groups; I (Placebo), II (Hedera helix), III (Dexamethasone) and IV (Control). All mice except controls were sensitized and challenged with ovalbumin. Then, mice in group I received saline, group II 100 mg/kg Hedera helix and group III 1 mg/kg dexamethasone via orogastic gavage once daily for one week. Airway histopathology was evaluated by using light and electron microscopy in all groups.Goblet cell numbers and thicknesses of basement membrane were found significantly lower in group II, but there was no statistically significant difference in terms of number of mast cells, thicknesses of epithelium and subepithelial smooth muscle layers between group I and II. When Hedera helix and dexamethasone groups were compared with each other, thickness of epithelium, subepithelial muscle layers, number of mast cells and goblet cells of group III were significantly ameliorated when compared with the group II. Although Hedera helix administration reduced only goblet cell counts and the thicknesses of basement membrane in the asthmatic airways, dexamethasone ameliorated all histopathologic parameters except thickness of basement membrane better than Hedera helix.

Dimerization of the docking/adaptor protein HEF1 via a carboxy-terminal helix-loop-helix domain.

Science.gov (United States)

Law, S F; Zhang, Y Z; Fashena, S J; Toby, G; Estojak, J; Golemis, E A

1999-10-10

HEF1, p130(Cas), and Efs define a family of multidomain docking proteins which plays a central coordinating role for tyrosine-kinase-based signaling related to cell adhesion. HEF1 function has been specifically implicated in signaling pathways important for cell adhesion and differentiation in lymphoid and epithelial cells. While the SH3 domains and SH2-binding site domains (substrate domains) of HEF1 family proteins are well characterized and binding partners known, to date the highly conserved carboxy-terminal domains of the three proteins have lacked functional definition. In this study, we have determined that the carboxy-terminal domain of HEF1 contains a divergent helix-loop-helix (HLH) motif. This motif mediates HEF1 homodimerization and HEF1 heterodimerization with a recognition specificity similar to that of the transcriptional regulatory HLH proteins Id2, E12, and E47. We had previously demonstrated that the HEF1 carboxy-terminus expressed as a separate domain in yeast reprograms cell division patterns, inducing constitutive pseudohyphal growth. Here we show that pseudohyphal induction by HEF1 requires an intact HLH, further supporting the idea that this motif has an effector activity for HEF1, and implying that HEF1 pseudohyphal activity derives in part from interactions with yeast helix-loop-helix proteins. These combined results provide initial insight into the mode of function of the HEF1 carboxy-terminal domain and suggest that the HEF1 protein may interact with cellular proteins which control differentiation. Copyright 1999 Academic Press.

Evaluation of impairment of DNA in marine gastropod, Morula granulata as a biomarker of marine pollution.

Science.gov (United States)

Sarkar, A; Bhagat, Jacky; Sarker, Subhodeep

2014-08-01

The impairment of DNA in marine gastropod Morula granulata was evaluated in terms of the loss of DNA integrity in the species as a measure of the impact of genotoxic contaminants prevalent in the marine environment along the coast of Goa, India. The extent of DNA damage occurred in the marine gastropods collected from different sampling sites such as Arambol, Anjuna, Sinquerim, Dona Paula, Bogmalo, Hollant, Velsao, Betul and Palolem along the coast of Goa was measured following the technique of partial alkaline unwinding as well as comet assays. The highest DNA integrity was observed at Arambol (F, 0.75), identified as the reference site, whereas the lowest DNA integrity at Hollant (F, 0.33) situated between the two most contaminated sites at Bogmalo and Velsao. The impact of genotoxic contaminants on marine gastropods was pronounced by their low DNA integrity at Sinquerim (F, 0.40) followed by Betul (F, 0.47), Velsao (F, 0.51), Anjuna (F, 0.54), Bogmalo (F, 0.55), Dona Paula (F, 0.67) and Palolem (F, 0.70). The extent of DNA damage occurred in M. granulata due to ecotoxicological impact of the prevailing marine pollutants along the coast of Goa was further substantiated by comet assay and expressed in terms of %head-DNA, %tail DNA, tail length and Olive tail moment. The single cell gel electrophoresis of M. granulata clearly showed relatively higher olive tail moment in the marine gastropod from the contaminated sites, Anjuna, Hollant, Velsao and Betul. The variation in the mean %head DNA at different sampling sites clearly indicated that the extent of DNA damage in marine gastropod increases with the increase in the levels of contamination at different sampling sites along the coast. The stepwise multiple regression analysis of the water quality parameters showed significant correlation between the variation in DNA integrity and PAH in combination with NO3, salinity and PO4 (R¯(2), 0.90). The measurement of DNA integrity in M. granulata thus provides an early

Species diversity of planktonic gastropods (Pteropoda and Heteropoda) from six ocean regions based on DNA barcode analysis

Science.gov (United States)

Jennings, Robert M.; Bucklin, Ann; Ossenbrügger, Holger; Hopcroft, Russell R.

2010-12-01

Pteropods and heteropods are two distinct groups of holoplanktonic gastropods whose species and genetic diversity remain poorly understood, despite their ubiquity in the world's oceans. Some species apparently attain near cosmopolitan distributions, implying long-distance dispersal or cryptic species assemblages. We present the first multi-regional and species-rich molecular dataset of holoplanktonic gastropods, comprising DNA barcodes from the mitochondrial cytochrome c oxidase I subunit gene (COI) from 115 individuals of 41 species sampled from six ocean regions across the globe. Molecular analysis and assessment of barcoding utility supported the validity of several morphological subspecies and forms (e.g. of Creseis virgula and Limacina helicina), while others were not supported (e.g. Cavolinia uncinata). Significant genetic variation was observed among conspecific specimens collected in different geographic regions for some species, particularly in euthecosomatous pteropods. Several species of euthecosomes showed no evidence of genetic separation among distant ocean regions. Overall, we suggest some taxonomic revision of the holoplanktonic gastropods will be required, pending a more complete molecular inventory of these groups.

Effects of ocean acidification on the shells of four Mediterranean gastropod species near a CO2 seep.

Science.gov (United States)

Duquette, Ashley; McClintock, James B; Amsler, Charles D; Pérez-Huerta, Alberto; Milazzo, Marco; Hall-Spencer, Jason M

2017-11-30

Marine CO 2 seeps allow the study of the long-term effects of elevated pCO 2 (ocean acidification) on marine invertebrate biomineralization. We investigated the effects of ocean acidification on shell composition and structure in four ecologically important species of Mediterranean gastropods (two limpets, a top-shell snail, and a whelk). Individuals were sampled from three sites near a volcanic CO 2 seep off Vulcano Island, Italy. The three sites represented ambient (8.15pH), moderate (8.03pH) and low (7.73pH) seawater mean pH. Shell mineralogy, microstructure, and mechanical strength were examined in all four species. We found that the calcite/aragonite ratio could vary and increased significantly with reduced pH in shells of one of the two limpet species. Moreover, each of the four gastropods displayed reductions in either inner shell toughness or elasticity at the Low pH site. These results suggest that near-future ocean acidification could alter shell biomineralization and structure in these common gastropods. Copyright © 2017 Elsevier Ltd. All rights reserved.

Threatened freshwater and terrestrial molluscs (Mollusca, Gastropoda et Bivalvia of Santa Catarina State, Southern Brazil: check list and evaluation of regional threats

Directory of Open Access Journals (Sweden)

2011-06-01

Full Text Available A total of nineteen continental native mollusc species are confirmed for the Santa Catarina State (SC(organized in ten Genera and seven Families, one aquatic Prosobranchia/Caenogastropoda (Ampullariidae,six Pulmonata terrestrial gastropods (one Ellobiidae, three Megalobulimidae and two micro-snails –Charopidae and Streptaxidae and twelve freshwater mussels (eight Mycetopodidae and four Hyriidae. Thesespecies are designated by the International Union for Conservation of the Nature – IUCN as follows: seven as"Vulnerable", six "In Danger" and six “Without Category Established”. The general regional threats that thesespecies are subjected to are briefly analyzed.

The basic helix-loop-helix region of the transcriptional repressor hairy and enhancer of split 1 is preorganized to bind DNA

NARCIS (Netherlands)

Popovic, Matija; Wienk, Hans; Coglievina, Maristella; Boelens, Rolf; Pongor, Sándor; Pintar, Alessandro

2014-01-01

Hairy and enhancer of split 1, one of the main downstream effectors in Notch signaling, is a transcriptional repressor of the basic helix-loop-helix (bHLH) family. Using nuclear magnetic resonance methods, we have determined the structure and dynamics of a recombinant protein, H1H, which includes an

Impact of toxic cyanobacteria on gastropods and microcystin accumulation in a eutrophic lake (Grand-Lieu, France) with special reference to Physa (= Physella) acuta

International Nuclear Information System (INIS)

Lance, Emilie; Brient, Luc; Carpentier, Alexandre; Acou, Anthony; Marion, Loic; Bormans, Myriam; Gerard, Claudia

2010-01-01

Hepatotoxic microcystins (MCs) produced by cyanobacteria are known to accumulate in gastropods following grazing of toxic cyanobacteria and/or absorption of MCs dissolved in water, with adverse effects on life history traits demonstrated in the laboratory. In the field, such effects may vary depending on species, according to their relative sensitivity and ecology. The aims of this study were to i) establish how various intensities of MC-producing cyanobacteria proliferations alter the structure of gastropod community and ii) compare MC tissue concentration in gastropods in the field with those obtained in our previous laboratory experiments on the prosobranch Potamopyrgus antipodarum and the pulmonate Lymnaea stagnalis. We explored these questions through a one-year field study at three stations at Grand-Lieu Lake (France) affected by different intensities of cyanobacteria proliferations. A survey of the community structure and MC content of both cyanobacteria and gastropods was associated with a caging experiment involving P. antipodarum and L. stagnalis. In total, 2592 gastropods belonging to 7 prosobranch and 16 pulmonate species were collected. However, distribution among the stations was unequal with 62% vs 2% of gastropods sampled respectively at the stations with the lowest vs highest concentrations of MC. Irrespective of the station, pulmonates were always more diverse, more abundant and occurred at higher frequencies than prosobranchs. Only the pulmonate Physa acuta occurred at all stations, with abundance and MC tissue concentration (≤ 4.32 μg g DW -1 ) depending on the degrees of MC-producing cyanobacteria proliferations in the stations; therefore, P. acuta is proposed as a potential sentinel species. The caging experiment demonstrated a higher MC accumulation in L. stagnalis (≤ 0.36 μg g DW -1 for 71% of individuals) than in P. antipodarum (≤ 0.02 μg g DW -1 for 12%), corroborating previous laboratory observations. Results are discussed in

Mode conversions by a discontinuous junction of two helix loaded waveguides

International Nuclear Information System (INIS)

Choe, J.Y.; Ahn, S.; Ganquly, A.K.; Uhm, H.S.

1983-01-01

For various reasons, it is desirable to vary the primary propagating mode from one section of the waveguide to another. We choose the base structure to be the sheath helix loaded waveguide. Specifically, we join two physically different helix loaded waveguides axisymmetrically, thereby providing the required discontinuities at the junction (Z = 0). The helix loaded waveguide is more advantageous to the simple waveguide in that the helix mode that exists uniquely in the helix waveguide in addition to the usual fast wave hybrid modes, is without cutoff and thus behaves like a transmission line. In order to obtain the mode conversion rates, we expand the waves in the both sides of the junction with its own eigenmodes including the evanescent modes, and by matching fields at the junction (Z = 0) obtain the matrix equation for the coefficients for the eigenmodes in both sides. By choosing the propagating incident wave (Z = 0) the resulting outgoing waves in the other end (Z > 0) will be computed from the matrix equation. A computer program is devised to solve the suitably truncated matrix equation, and the numerical examples for the mode conversion rates with the parameter variations will be presented. The relevant physical parameters to yield discontinuities at the junction are the radii of the outer conductor and the helix wire and the pitch angle of the helix. Special emphases are on the conversion rates from the helix mode (Z 0) for the application to the tapered gyrotron amplifier

Mechanical unfolding reveals stable 3-helix intermediates in talin and α-catenin.

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Vasyl V Mykuliak

2018-04-01

Full Text Available Mechanical stability is a key feature in the regulation of structural scaffolding proteins and their functions. Despite the abundance of α-helical structures among the human proteome and their undisputed importance in health and disease, the fundamental principles of their behavior under mechanical load are poorly understood. Talin and α-catenin are two key molecules in focal adhesions and adherens junctions, respectively. In this study, we used a combination of atomistic steered molecular dynamics (SMD simulations, polyprotein engineering, and single-molecule atomic force microscopy (smAFM to investigate unfolding of these proteins. SMD simulations revealed that talin rod α-helix bundles as well as α-catenin α-helix domains unfold through stable 3-helix intermediates. While the 5-helix bundles were found to be mechanically stable, a second stable conformation corresponding to the 3-helix state was revealed. Mechanically weaker 4-helix bundles easily unfolded into a stable 3-helix conformation. The results of smAFM experiments were in agreement with the findings of the computational simulations. The disulfide clamp mutants, designed to protect the stable state, support the 3-helix intermediate model in both experimental and computational setups. As a result, multiple discrete unfolding intermediate states in the talin and α-catenin unfolding pathway were discovered. Better understanding of the mechanical unfolding mechanism of α-helix proteins is a key step towards comprehensive models describing the mechanoregulation of proteins.

New porcellioidean gastropods from early Devonian of Royal Creek area, Yukon Territory, Canada, with notes on their early phylogeny

Science.gov (United States)

Fryda, J.; Blodgett, R.B.; Lenz, A.C.; Manda, S.

2008-01-01

This paper presents a description of new gastropods belonging to the superfamily Porcellioidea (Vetigastropoda) from the richly diverse Lower Devonian gastropod fauna of the Road River Formation in the Royal Creek area, Yukon Territory. This fauna belongs to Western Canada Province of the Old World Realm. The Pragian species Porcellia (Porcellia) yukonensis n. sp. and Porcellia (Paraporcellia) sp. represent the oldest presently known members of subgenera Porcellia (Porcellia) and Porcellia (Paraporcellia). Their simple shell ornamentation fits well with an earlier described evolutionary trend in shell morphology of the Porcellinae. Late Pragian to early Emsian Perryconcha pulchra n. gen. and n. sp. is the first member of the Porcellioidea bearing a row of tremata on adult teleoconch whorls. The occurrence of this shell feature in the Porcellioidea is additional evidence that the evolution of the apertural slit was much more complicated than has been proposed in classical models of Paleozoic gastropod evolution. Copyright ?? 2008, The Paleontological Society.

DNA-like double helix formed by peptide nucleic acid

DEFF Research Database (Denmark)

Wittung, P; Nielsen, Peter E.; Buchardt, O

1994-01-01

Although the importance of the nucleobases in the DNA double helix is well understood, the evolutionary significance of the deoxyribose phosphate backbone and the contribution of this chemical entity to the overall helical structure and stability of the double helix is not so clear. Peptide nucleic...

Hydroxyproline Ring Pucker Causes Frustration of Helix Parameters in the Collagen Triple Helix

Science.gov (United States)

Ying Chow, W.; Bihan, Dominique; Forman, Chris J.; Slatter, David A.; Reid, David G.; Wales, David J.; Farndale, Richard W.; Duer, Melinda J.

2015-07-01

Collagens, the most abundant proteins in mammals, are defined by their triple-helical structures and distinctive Gly-Xaa-Yaa repeating sequence, where Xaa is often proline and Yaa, hydroxyproline (Hyp/O). It is known that hydroxyproline in the Yaa position stabilises the triple helix, and that lack of proline hydroxylation in vivo leads to dysfunctional collagen extracellular matrix assembly, due to a range of factors such as a change in hydration properties. In addition, we note that in model peptides, when Yaa is unmodified proline, the Xaa proline has a strong propensity to adopt an endo ring conformation, whilst when Yaa is hydroxyproline, the Xaa proline adopts a range of endo and exo conformations. Here we use a combination of solid-state NMR spectroscopy and potential energy landscape modelling of synthetic triple-helical collagen peptides to understand this effect. We show that hydroxylation of the Yaa proline causes the Xaa proline ring conformation to become metastable, which in turn confers flexibility on the triple helix.

Nature of the Charged-Group Effect on the Stability of the C-Peptide Helix

Science.gov (United States)

Shoemaker, Kevin R.; Kim, Peter S.; Brems, David N.; Marqusee, Susan; York, Eunice J.; Chaiken, Irwin M.; Stewart, John M.; Baldwin, Robert L.

1985-04-01

The residues responsible for the pH-dependent stability of the helix formed by the isolated C-peptide (residues 1-13 of ribonuclease A) have been identified by chemical synthesis of analogues and measurement of their helix-forming properties. Each of the residues ionizing between pH 2 and pH 8 has been replaced separately by an uncharged residue. Protonation of Glu-2- is responsible for the sharp decrease in helix stability between pH 5 and pH 2, and deprotonation of His-12+ causes a similar decrease between pH 5 and pH 8. Glu-9- is not needed for helix stability. The results cannot be explained by the Zimm-Bragg model and host-guest data for α -helix formation, which predict that the stability of the C-peptide helix should increase when Glu-2- is protonated or when His-12+ is deprotonated. Moreover, histidine+ is a strong helix-breaker in host-guest studies. In proteins, acidic and basic residues tend to occur at opposite ends of α -helices: acidic residues occur preferentially near the NH2-terminal end and basic residues near the COOH-terminal end. A possible explanation, based on a helix dipole model, has been given [Blagdon, D. E. & Goodman, M. (1975) Biopolymers 14, 241-245]. Our results are consistent with the helix dipole model and they support the suggestion that the distribution of charged residues in protein helices reflects the helix-stabilizing propensity of those residues. Because Glu-9 is not needed for helix stability, a possible Glu-9-\\cdots His-12+ salt bridge does not contribute significantly to helix stability. The role of a possible Glu-2-\\cdots Arg-10+ salt bridge has not yet been evaluated. A charged-group effect on α -helix stability in water has also been observed in a different peptide system [Ihara, S., Ooi, T. & Takahashi, S. (1982) Biopolymers 21, 131-145]: block copolymers containing (Ala)20 and (Glu)20 show partial helix formation at low temperatures, pH 7.5, where the glutamic acid residues are ionized. (Glu)20(Ala)20Phe forms a

A Baseline Measure of Tree and Gastropod Biodiversity in Replanted and Natural Mangrove Stands in Malaysia: Langkawi Island and Sungai Merbok

Science.gov (United States)

Hookham, Brenda; Shau-Hwai, Aileen Tan; Dayrat, Benoit; Hintz, William

2014-01-01

The diversities of mangrove trees and of their associated gastropods were assessed for two mangrove regions on the west coast of Peninsular Malaysia: Langkawi Island and Sungai Merbok. The mangrove area sampled on Langkawi Island was recently logged and replanted, whereas the area sampled in Sungai Merbok was part of a protected nature reserve. Mangrove and gastropod diversity were assessed in four 50 m2 (10 × 5 m) sites per region. The species richness (S), Shannon Index (H’) and Evenness Index (J’) were calculated for each site, and the mean S, H’ and J’ values were calculated for each region. We report low tree and gastropod S, H’ and J’ values in all sites from both regions. For Langkawi Island, the mean S, H’ and J’ values for mangrove trees were S = 2.00±0, H’ = 0.44±0.17 and J’ = 0.44±0.17; the mean S, H’ and J’ values for gastropods were S = 4.00±1.63, H’ = 0.96±0.41 and J’ = 0.49±0.06. In Sungai Merbok, the mean S, H’ and J’ values for mangrove trees were S = 1.33±0.58, H’ = 0.22±0.39 and J’ = 0.22 ±0.39; the mean S, H’ and J’ values for gastropods were S = 4.75±2.22, H’ = 1.23±0.63 and J’ = 0.55±0.12. This study emphasises the need for baseline biodiversity measures to be established in mangrove ecosystems to track the impacts of anthropogenic disturbances and to inform management and restoration efforts. PMID:25210584

"Special Issue": Regional Dimensions of the Triple Helix Model

Science.gov (United States)

Todeva, Emanuela; Danson, Mike

2016-01-01

This paper introduces the rationale for the special issue and its contributions, which bridge the literature on regional development and the Triple Helix model. The concept of the Triple Helix at the sub-national, and specifically regional, level is established and examined, with special regard to regional economic development founded on…

A smallest 6 kda metalloprotease, mini-matrilysin, in living world: a revolutionary conserved zinc-dependent proteolytic domain- helix-loop-helix catalytic zinc binding domain (ZBD

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Yu Wei-Hsuan

2012-05-01

Full Text Available Abstract Background The Aim of this study is to study the minimum zinc dependent metalloprotease catalytic folding motif, helix B Met loop-helix C, with proteolytic catalytic activities in metzincin super family. The metzincin super family share a catalytic domain consisting of a twisted five-stranded β sheet and three long α helices (A, B and C. The catalytic zinc is at the bottom of the cleft and is ligated by three His residues in the consensus sequence motif, HEXXHXXGXXH, which is located in helix B and part of the adjacent Met turn region. An interesting question is - what is the minimum portion of the enzyme that still possesses catalytic and inhibitor recognition?” Methods We have expressed a 60-residue truncated form of matrilysin which retains only the helix B-Met turn-helix C region and deletes helix A and the five-stranded β sheet which form the upper portion of the active cleft. This is only 1/4 of the full catalytic domain. The E. coli derived 6 kDa MMP-7 ZBD fragments were purified and refolded. The proteolytic activities were analyzed by Mca-Pro-Leu-Gly-Leu-Dpa-Ala-Arg-NH2 peptide assay and CM-transferrin zymography analysis. SC44463, BB94 and Phosphoramidon were computationally docked into the 3day structure of the human MMP7 ZBD and TAD and thermolysin using the docking program GOLD. Results This minimal 6 kDa matrilysin has been refolded and shown to have proteolytic activity in the Mca-Pro-Leu-Gly-Leu-Dpa-Ala-Arg-NH2 peptide assay. Triton X-100 and heparin are important factors in the refolding environment for this mini-enzyme matrilysin. This minienzyme has the proteolytic activity towards peptide substrate, but the hexamer and octamer of the mini MMP-7 complex demonstrates the CM-transferrin proteolytic activities in zymographic analysis. Peptide digestion is inhibited by SC44463, specific MMP7 inhibitors, but not phosphorimadon. Interestingly, the mini MMP-7 can be processed by autolysis and producing ~ 6�

Freshwater gastropods of Neogene and Quaternary lake systems of Europe - state of the art and outlook

Science.gov (United States)

Neubauer, Thomas A.; Harzhauser, Mathias; Mandic, Oleg; Kroh, Andreas

2013-04-01

Globally, about 4000 extant species of freshwater gastropod species have been described. In contrast, only 225 species are listed by MollBase2012 for North- and Central Europe. Many of these are rare species, limited to certain springs and in fact the typical diversity of gastropods in lakes of North and Central Europe is much lower. The high number is boosted by several highly speciose endemic radiations in long-lived ancient lakes, which are hotspots for biodiversity. These long-lived ancient lakes provide key examples for understanding evolutionary processes and therefore are intensively studied. During the Neogene, Europe's geodynamic history gave rise to several such long-lived lakes with conspicuous endemic radiations. However, these lacustrine systems are rare today as well as in the past compared to the enormous numbers of "normal" lakes. Most extant European lakes are mainly results of the Ice Ages and are due to their geologically temporary nature largely confined to the Pleistocene-Holocene. Also deposits of streams, springs, and groundwater, which today are inhabited by species-rich gastropod assemblages, are rarely preserved. Thus, the pre-Quaternary lacustrine record is biased towards long-lived systems. Apart from few general overviews precise studies on the γ-diversities of the post-Oligocene European lake systems and the shifting biodiversity in European freshwater systems through space and time are entirely missing. Even for the modern faunas, literature on large-scale freshwater gastropod diversity in extant lakes is scarce and lacks a statistical approach. Building upon a great amount of existing literature, a new project will provide the first detailed assessment of the composition of European freshwater gastropods during the Neogene and Quaternary at species, genus and family levels, with emphasis on lake faunas. The γ-diversity of several hundred modern and fossil European lakes will be evaluated. Data will be made available permanently for

[NADPH-diaphorase activity in digestive system of gastropod molluscs Achatina fulica and Littorina littorea].

Science.gov (United States)

Zaĭtseva, O V; Kuznetsova, T V; Markosova, T G

2009-01-01

Localization and peculiarities of NO-ergic elements were studied for he first time throughout the entire length of digestive tract of the marine gastropod mollusc Achatina fulica (Prosobranchia) and the terrestrial molusc Littorina littorea (Pulmonata) by using histochemical method of detection of NADPH-diaphorase (NADPHd). NO-ergic cells and fibers were revealed in all parts of the mollusc digestive tract beginning from pharynx. An intensive NADPHd activity was found in many intraepithelial cells of the open type and in their processes in intra- and subepithelial nerve plexuses, single subepithelial neurons, granular connective tissue cells, and numerous nerve fibers among muscle elements of he digestive tract wall as well as in nerves innervating the tract. NADPHd was also present in receptor cells of he oral area and in the central A. fulica ganglia participating in innervation of the digestive tract. The digestive tract NO-ergic system ofA. fulica has a more complex organization that that of L. littorea. In the A. fulica pharynx, stomach, and midgut, directly beneath epithelium, there is revealed a complex system of glomerular structures formed by thin NADPHd-positive nerve fibers coming from the side of epithelium. More superficially under the main groups of muscle elements, small agglomerations of NADPHd-positive neurons are seen, which could be considered as primitive, non-formed microganglia. Peculiarities of distribution and a possible functional role of NO-ergic elements in the digestive tract of molluscs are discussed as compared with other invertebrate and vertebrate animals.

Terrestrial cooling in Northern Europe during the eocene-oligocene transition.

Science.gov (United States)

Hren, Michael T; Sheldon, Nathan D; Grimes, Stephen T; Collinson, Margaret E; Hooker, Jerry J; Bugler, Melanie; Lohmann, Kyger C

2013-05-07

Geochemical and modeling studies suggest that the transition from the "greenhouse" state of the Late Eocene to the "icehouse" conditions of the Oligocene 34-33.5 Ma was triggered by a reduction of atmospheric pCO2 that enabled the rapid buildup of a permanent ice sheet on the Antarctic continent. Marine records show that the drop in pCO2 during this interval was accompanied by a significant decline in high-latitude sea surface and deep ocean temperature and enhanced seasonality in middle and high latitudes. However, terrestrial records of this climate transition show heterogeneous responses to changing pCO2 and ocean temperatures, with some records showing a significant time lag in the temperature response to declining pCO2. We measured the Δ47 of aragonite shells of the freshwater gastropod Viviparus lentus from the Solent Group, Hampshire Basin, United Kingdom, to reconstruct terrestrial temperature and hydrologic change in the North Atlantic region during the Eocene-Oligocene transition. Our data show a decrease in growing-season surface water temperatures (~10 °C) during the Eocene-Oligocene transition, corresponding to an average decrease in mean annual air temperature of ~4-6 °C from the Late Eocene to Early Oligocene. The magnitude of cooling is similar to observed decreases in North Atlantic sea surface temperature over this interval and occurs during major glacial expansion. This suggests a close linkage between atmospheric carbon dioxide concentrations, Northern Hemisphere temperature, and expansion of the Antarctic ice sheets.

The gastropod shell has been co-opted to kill parasitic nematodes.

Science.gov (United States)

Rae, R

2017-07-06

Exoskeletons have evolved 18 times independently over 550 MYA and are essential for the success of the Gastropoda. The gastropod shell shows a vast array of different sizes, shapes and structures, and is made of conchiolin and calcium carbonate, which provides protection from predators and extreme environmental conditions. Here, I report that the gastropod shell has another function and has been co-opted as a defense system to encase and kill parasitic nematodes. Upon infection, cells on the inner layer of the shell adhere to the nematode cuticle, swarm over its body and fuse it to the inside of the shell. Shells of wild Cepaea nemoralis, C. hortensis and Cornu aspersum from around the U.K. are heavily infected with several nematode species including Caenorhabditis elegans. By examining conchology collections I show that nematodes are permanently fixed in shells for hundreds of years and that nematode encapsulation is a pleisomorphic trait, prevalent in both the achatinoid and non-achatinoid clades of the Stylommatophora (and slugs and shelled slugs), which diverged 90-130 MYA. Taken together, these results show that the shell also evolved to kill parasitic nematodes and this is the only example of an exoskeleton that has been co-opted as an immune system.

The C-Terminal RpoN Domain of sigma54 Forms an unpredictedHelix-Turn-Helix Motif Similar to domains of sigma70

Energy Technology Data Exchange (ETDEWEB)

Doucleff, Michaeleen; Malak, Lawrence T.; Pelton, Jeffrey G.; Wemmer, David E.

2005-11-01

The ''{delta}'' subunit of prokaryotic RNA-polymerase allows gene-specific transcription initiation. Two {sigma} families have been identified, {sigma}{sup 70} and {sigma}{sup 54}, which use distinct mechanisms to initiate transcription and share no detectable sequence homology. Although the {sigma}{sup 70}-type factors have been well characterized structurally by x-ray crystallography, no high-resolution structural information is available for the {sigma}{sup 54}-type factors. Here we present the NMR derived structure of the C-terminal domain of {sigma}{sup 54} from Aquifex aeolicus. This domain (Thr323 to Gly389), which contains the highly conserved RpoN box sequence, consists of a poorly structured N-terminal tail followed by a three-helix bundle, which is surprisingly similar to domains of the {sigma}{sup 70}-type proteins. Residues of the RpoN box, which have previously been shown to be critical for DNA binding, form the second helix of an unpredicted helix-turn-helix motif. This structure's homology with other DNA binding proteins, combined with previous biochemical data, suggest how the C-terminal domain of {sigma}{sup 54} binds to DNA.

Feeding preferences of the endemic gastropod Astraea latispina in relation to chemical defenses of Brazilian tropical seaweeds

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PEREIRA R. C.

2002-01-01

Full Text Available Seaweed preference by the Brazilian endemic gastropod Astraea latispina was examined in the laboratory to evaluate the role of secondary metabolites in determining food choice. Of three species of seaweeds examined, Plocamium brasiliense was highly preferred; less so were Sargassum furcatum and Dictyota cervicornis were preferred less. Extracts and/or pure major metabolites of the two potentially chemically-defended seaweeds (P. brasiliense and D. cervicornis were tested as feeding deterrents against A. latispina. Algal extract assays demonstrated that three concentrations of crude organic extract of the red alga P. brasiliense (50%, 100%: natural concentration, and 200% of dry weight: dw did not affect feeding of this gastropod. In contrast, the three concentrations of crude organic extract of the brown alga D. cervicornis (50%, 100% and 200% dw inhibited feeding by A. latispina. The chemical deterrent property of D. cervicornis extract against the gastropod A. latispina occurred due to a mixture of the secodolastane diterpenes isolinearol/linearol (4:1 -- 0.08% dry weight. This is the first report showing that Dictyota cervicornis produces a chemical defense against herbivores using secodolastane diterpenoid. In addition, these results widen the action spectrum of secondary metabolites found in seaweed belonging to this brown algal genus.

Feeding preferences of the endemic gastropod Astraea latispina in relation to chemical defenses of Brazilian tropical seaweeds

Directory of Open Access Journals (Sweden)

R. C. PEREIRA

Full Text Available Seaweed preference by the Brazilian endemic gastropod Astraea latispina was examined in the laboratory to evaluate the role of secondary metabolites in determining food choice. Of three species of seaweeds examined, Plocamium brasiliense was highly preferred; less so were Sargassum furcatum and Dictyota cervicornis were preferred less. Extracts and/or pure major metabolites of the two potentially chemically-defended seaweeds (P. brasiliense and D. cervicornis were tested as feeding deterrents against A. latispina. Algal extract assays demonstrated that three concentrations of crude organic extract of the red alga P. brasiliense (50%, 100%: natural concentration, and 200% of dry weight: dw did not affect feeding of this gastropod. In contrast, the three concentrations of crude organic extract of the brown alga D. cervicornis (50%, 100% and 200% dw inhibited feeding by A. latispina. The chemical deterrent property of D. cervicornis extract against the gastropod A. latispina occurred due to a mixture of the secodolastane diterpenes isolinearol/linearol (4:1 -- 0.08% dry weight. This is the first report showing that Dictyota cervicornis produces a chemical defense against herbivores using secodolastane diterpenoid. In addition, these results widen the action spectrum of secondary metabolites found in seaweed belonging to this brown algal genus.

Identification of basic/helix-loop-helix transcription factors reveals candidate genes involved in anthocyanin biosynthesis from the strawberry white-flesh mutant

OpenAIRE

Zhao, Fengli; Li, Gang; Hu, Panpan; Zhao, Xia; Li, Liangjie; Wei, Wei; Feng, Jiayue; Zhou, Houcheng

2018-01-01

As the second largest transcription factor family in plant, the basic helix-loop-helix (bHLH) transcription factor family, characterized by the conserved bHLH domain, plays a central regulatory role in many biological process. However, the bHLH transcription factor family of strawberry has not been systematically identified, especially for the anthocyanin biosynthesis. Here, we identified a total of 113 bHLH transcription factors and described their chromosomal distribution and bioinformatics...

Effect of cadmium and zinc on antioxidant enzyme activity in the gastropod, Achatina fulica.

Science.gov (United States)

Chandran, Rashmi; Sivakumar, A A; Mohandass, S; Aruchami, M

2005-01-01

Heavy metal stress results in the production of O(2)(.-), H(2)O(2) and (.)OH, which affect various cellular processes, mostly the functioning of membrane systems. Cells are normally protected against free oxyradicals by the operation of intricate antioxidant systems. The aim of the present work is to examine the effect of CdCl(2) and ZnSO(4) on antioxidative enzyme activity in the gastropod, Achatina fulica. The concentrations of antioxidant enzymes--superoxide dismutase (SOD), catalase (Cat) and glutathione peroxidase (GPx)--and nonenzymatic antioxidants--glutathione and vitamin-C--were found to be decreased in both digestive gland and kidney of the gastropod, Achatina fulica treated with individual concentrations of 0.5 ppm and 1ppm of CdCl(2) and ZnSO(4), compared to that of control animals. Based on the above study, it is evident that Achatina fulica can be used as a bioindicator to monitor the environmental heavy metal pollution.

Taxonomic diversity dynamics of early cretaceous brachiopods and gastropods in the Azerbaijanian domains of the Lesser Caucasus (Neo-Tethys Ocean

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Ruban Dmitry A.

2014-01-01

Full Text Available Palaeontological data available from the Azerbaijanian domains (Somkhit-Agdam, Sevan-Karabakh, and Miskhan-Kafan tectonic zones of the Lesser Caucasus permit reconstruction of the regional taxonomic diversity dynamics of two groups of Early Cretaceous marine benthic invertebrates. Stratigraphical ranges of 31 species and 14 genera of brachiopods and 40 species and 31 genera of gastropods are considered. The total number of species and genera of brachiopods was low in the Berriasian-Valanginian and then rose to peak in the Barremian. Then, the diversity declined in the Aptian, and brachiopods are not known regionally from the Albian. Gastropods appeared in the Hauterivian and experienced a strong radiation in the Barremian. The diversity of species and genera declined in the Aptian (with a minor radiation in the Middle Aptian, and no gastropods are reported from the Albian. Globally, the number of brachiopod genera remained stable through the Early Cretaceous, and the number of gastropod genera increased stepwise with the maximum in the Albian. The regional and global patterns of the diversity dynamics differed for the both groups of marine benthic invertebrates. The Barremian maximum of the taxonomic diversity coincided with the regional flourishing of reefal ecosystems. The taxonomic diversity dynamics of brachiopods in the Azerbaijanian domains of the Lesser Caucasus is very similar to those of the Northern Caucasus, which is an evidence of proximity of these regions during the Early Cretaceous.

TOWARDS UNDERSTANDING OF HELIX B BASED CONFORMATIONAL DISEASES IN SERPIN

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Mohamad Aman Jairajpuri

2012-12-01

Full Text Available Serine protease inhibitors (serpins are a unique family of protease inhibitors that are prone to polymer formation due to their metastable nature and a complex inhibition mechanism that involves large scale conformational change. Helix B is in the shutter region near the strand 2A and strand 3A of �-sheet A, where reactive centre loop inserts during the serpin inhibition mechanism. Helix B region in serpins is a mutation hotspot for naturally occurring variants that result in pathological conditions due to polymerization. Helix B residues are completely buried in the native state and loop inserted latent state but not in the inhibitory loop inserted cleaved conformation. Native to cleaved transition during inhibition forms a large cavity in the shutter region, which invariably is the largest cavity in most serpins in native state. In a recent paper we had for the first time hypothesized that exposure of helix B at the N-terminal end is important for smooth insertion of the reactive center loop during serpin inhibition mechanism. It is therefore possible that natural variant that induces conformational deformation of helix B probably alter the cavity size which increases the rate of loop-sheet interaction between the monomers resulting in increased polymerization.

Ecological and geographical characteristics of algal communities on gastropod shells of the river Uzh

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N. M. Korniichuk

2017-07-01

Full Text Available Freshwater molluscs serve as test objects in the ecological monitoring of the environment, because they are able to extract in indicator quantity from the environment and accumulate in their bodies radionuclides, various macro- and micronutrients, toxic substances of inorganic and organic origin, and so on. The gastropods are a taxonomically diverse, ecologically plastic and rather widespread group of aquatic organisms, whose role in the life of freshwater ecosystems is very important. Molluscs often have various interactions in biogeocenoses that determines their trophic net. As a rule, these interactions occur in the form of ectocommensalism, endocommensalism, supercrescence, predation or parasitism. The latter type of interaction is the subject of many studies, but the epibionts of gastropods and bivalves have practically not been studied and this research is an effort towards filling this gap. Species composition of algal epibionts identifies specific sensitivity to the effects of certain environmental factors and reflects the processes occurring in their ecosystem water bodies. This determines their efficient use for analyzing changes of water bodies as aquatic habitat, particularly in terms of complex anthropogenic pressure on aquatic ecosystems. The aim of the research was to determine the ecological characteristics of algal communities on gastropod shells: Lymnaea stagnalis, L. auricularia and Viviparus viviparus (the Uzh river, Korosten district, Zhytomyr region. Identified microalgae communities were grouped and studied according to such indices as: confinedness to the habitat (substrate, temperature, fluidity and water oxygenating, saprobiological characteristics according to the Pantle-Buck system in the modification of Sladecek and Watanabe, salinity according to Kolbe’s system, pH at Hustedt scale in the interpretation of M. M. Davydova and geographical limitations of the objects of study. Algal fouling on the shells L. stagnalis

Nucleic acid helix structure determination from NMR proton chemical shifts

Energy Technology Data Exchange (ETDEWEB)

Werf, Ramon M. van der; Tessari, Marco; Wijmenga, Sybren S., E-mail: S.Wijmenga@science.ru.nl [Radboud University Nijmegen, Department of Biophysical Chemistry, Institute of Molecules and Materials (Netherlands)

2013-06-15

We present a method for de novo derivation of the three-dimensional helix structure of nucleic acids using non-exchangeable proton chemical shifts as sole source of experimental restraints. The method is called chemical shift de novo structure derivation protocol employing singular value decomposition (CHEOPS) and uses iterative singular value decomposition to optimize the structure in helix parameter space. The correct performance of CHEOPS and its range of application are established via an extensive set of structure derivations using either simulated or experimental chemical shifts as input. The simulated input data are used to assess in a defined manner the effect of errors or limitations in the input data on the derived structures. We find that the RNA helix parameters can be determined with high accuracy. We finally demonstrate via three deposited RNA structures that experimental proton chemical shifts suffice to derive RNA helix structures with high precision and accuracy. CHEOPS provides, subject to further development, new directions for high-resolution NMR structure determination of nucleic acids.

Genome-wide identification of basic helix-loop-helix and NF-1 motifs underlying GR binding sites in male rat hippocampus

DEFF Research Database (Denmark)

Pooley, John R.; Flynn, Ben P.; Grøntved, Lars

2017-01-01

linked to structural and organizational roles, an absence of major tethering partners for GRs, and little or no evidence for binding at negative glucocorticoid response elements. A basic helix-loop-helix motif closely resembling a NeuroD1 or Olig2 binding site was found underlying a subset of GR binding......Glucocorticoids regulate hippocampal function in part by modulating gene expression through the glucocorticoid receptor (GR). GR binding is highly cell type specific, directed to accessible chromatin regions established during tissue differentiation. Distinct classes of GR binding sites...

The Mitochondrial Genomes of the Nudibranch Mollusks, Melibe leonina and Tritonia diomedea, and Their Impact on Gastropod Phylogeny.

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Joseph L Sevigny

Full Text Available The phylogenetic relationships among certain groups of gastropods have remained unresolved in recent studies, especially in the diverse subclass Opisthobranchia, where nudibranchs have been poorly represented. Here we present the complete mitochondrial genomes of Melibe leonina and Tritonia diomedea (more recently named T. tetraquetra, two nudibranchs from the unrepresented Cladobranchia group, and report on the resulting phylogenetic analyses. Both genomes coded for the typical thirteen protein-coding genes, twenty-two transfer RNAs, and two ribosomal RNAs seen in other species. The twelve-nucleotide deletion previously reported for the cytochrome oxidase 1 gene in several other Melibe species was further clarified as three separate deletion events. These deletions were not present in any opisthobranchs examined in our study, including the newly sequenced M. leonina or T. diomedea, suggesting that these previously reported deletions may represent more recently divergent taxa. Analysis of the secondary structures for all twenty-two tRNAs of both M. leonina and T. diomedea indicated truncated d arms for the two serine tRNAs, as seen in some other heterobranchs. In addition, the serine 1 tRNA in T. diomedea contained an anticodon not yet reported in any other gastropod. For phylogenetic analysis, we used the thirteen protein-coding genes from the mitochondrial genomes of M. leonina, T. diomedea, and seventy-one other gastropods. Phylogenetic analyses were performed for both the class Gastropoda and the subclass Opisthobranchia. Both Bayesian and maximum likelihood analyses resulted in similar tree topologies. In the Opisthobranchia, the five orders represented in our study were monophyletic (Anaspidea, Cephalaspidea, Notaspidea, Nudibranchia, Sacoglossa. In Gastropoda, two of the three traditional subclasses, Opisthobranchia and Pulmonata, were not monophyletic. In contrast, four of the more recently named gastropod clades (Vetigastropoda

Regional Dimensions of the Triple Helix Model: Setting the Context

Science.gov (United States)

Todeva, Emanuela; Danson, Mike

2016-01-01

This paper introduces the rationale for the special issue and its contributions, which bridge the literature on regional development and the Triple Helix model. The concept of the Triple Helix at the sub-national, and specifically regional, level is established and examined, with special regard to regional economic development founded on…

FMRFamide receptors of Helix aspersa

International Nuclear Information System (INIS)

Payza, K.

1988-01-01

A receptor binding assay and an isolated heart bioassay were used to identify and characterize the FMRFamide receptors in Helix. In the heart bioassay, FMRFamide increased myocardial contraction force. A potent FMRFamide analog, desaminoTyr-Phe-norLeu-arg-Phe-amide (daYFnLRFamide), was used as a radioiodinated receptor ligand. The high affinity binding of 125 I-daYFnLRFamide at 0 degree C to Helix brain membranes was reversible, saturable, pH-dependent and specific, with a K D of 13-14 nM. A lower affinity (245 nM) site was also observed. Radioligand binding sites were also identified in the heart, male reproductive organs and digestive organs. The structure-activity relations (SAR) of cardiostimulation correlated with the specificity of 125 I-daYFnLRFamide binding to brain and heart receptors. The SAR were similar to those of other molluscan FMRFamide bioassays, except that they showed a marked preference for some analogs with blocked amino-terminals

Hermit crab (Decapoda, Anomura attraction to dead gastropod baits in an infralittoral algae bank

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Juarez C. B. Pezzuti

2002-06-01

Full Text Available Hermit crabs use gastropod shells as shelter and are adapted to follow chemical cues released from tissues of dead or injured gastropods as a way to find new and more adequate shells. The species composition, crab size, shell types adequacy and physical condition were compared between attracted individuals and crabs collected in previous samples. The previous sampling was carried out in five areas before each experiment. Then, five baits of crushed gastropods in nylon net bags were installed in these areas. Three samples were taken at 30min intervals, capturing all crabs within a circle of 60cm diameter. Attraction of hermit crabs was tested for four different gastropod baits to verify specificity of the chemical cues. Clibanarius antillensis, Pagurus brevidactylus and Paguristes tortugae were collected in the study area. Pagurus brevidactylus, the smallest species, turned out to be more attracted than the 2 other species. The results showed that attracted crabs utilized more gastropod shell types than that collected in previous samples, however shell utilization pattern did not differ between them. Attracted animals were slightly smaller (shield length than those collected in the previous samples but did not present significant differences in shell adequacy and condition. The four experimental baits attracted the crabs in similar ways not indicating a specific response from the crabs. The fact that attracted animals were smaller suggested that the attraction to dead gastropods might enable the acquisition of a new and larger shell and, consequently, chains of shell exchange between the attracted crabs.Ermitões utilizam conchas de gastrópodes para abrigo. Conchas novas e mais adequadas podem ser encontradas pelos ermitões pois estes são atraídos por substâncias químicas liberadas pelos tecidos de gastrópodes feridos ou mortos. A adequação, condição e tipo das conchas e a composição de espécies e o tamanho dos ermitões foram

Elevated temperature triggers human respiratory syncytial virus F protein six-helix bundle formation

International Nuclear Information System (INIS)

Yunus, Abdul S.; Jackson, Trent P.; Crisafi, Katherine; Burimski, Irina; Kilgore, Nicole R.; Zoumplis, Dorian; Allaway, Graham P.; Wild, Carl T.; Salzwedel, Karl

2010-01-01

Human respiratory syncytial virus (RSV) is a major cause of severe lower respiratory tract infection in infants, immunocompromised patients, and the elderly. The RSV fusion (F) protein mediates fusion of the viral envelope with the target cell membrane during virus entry and is a primary target for antiviral drug and vaccine development. The F protein contains two heptad repeat regions, HR1 and HR2. Peptides corresponding to these regions form a six-helix bundle structure that is thought to play a critical role in membrane fusion. However, characterization of six-helix bundle formation in native RSV F protein has been hindered by the fact that a trigger for F protein conformational change has yet to be identified. Here we demonstrate that RSV F protein on the surface of infected cells undergoes a conformational change following exposure to elevated temperature, resulting in the formation of the six-helix bundle structure. We first generated and characterized six-helix bundle-specific antibodies raised against recombinant peptides modeling the RSV F protein six-helix bundle structure. We then used these antibodies as probes to monitor RSV F protein six-helix bundle formation in response to a diverse array of potential triggers of conformational changes. We found that exposure of 'membrane-anchored' RSV F protein to elevated temperature (45-55 deg. C) was sufficient to trigger six-helix bundle formation. Antibody binding to the six-helix bundle conformation was detected by both flow cytometry and cell-surface immunoprecipitation of the RSV F protein. None of the other treatments, including interaction with a number of potential receptors, resulted in significant binding by six-helix bundle-specific antibodies. We conclude that native, untriggered RSV F protein exists in a metastable state that can be converted in vitro to the more stable, fusogenic six-helix bundle conformation by an increase in thermal energy. These findings help to better define the mechanism of

Crosslinked Aspartic Acids as Helix-Nucleating Templates.

Science.gov (United States)

Zhao, Hui; Liu, Qi-Song; Geng, Hao; Tian, Yuan; Cheng, Min; Jiang, Yan-Hong; Xie, Ming-Sheng; Niu, Xiao-Gang; Jiang, Fan; Zhang, Ya-Ou; Lao, Yuan-Zhi; Wu, Yun-Dong; Xu, Nai-Han; Li, Zi-Gang

2016-09-19

Described is a facile helix-nucleating template based on a tethered aspartic acid at the N-terminus [terminal aspartic acid (TD)]. The nucleating effect of the template is subtly influenced by the substituent at the end of the side-chain-end tether as indicated by circular dichroism, nuclear magnetic resonance, and molecular dynamics simulations. Unlike most nucleating strategies, the N-terminal amine is preserved, thus enabling further modification. Peptidomimetic estrogen receptor modulators (PERMs) constructed using this strategy show improved therapeutic properties. The current strategy can be regarded as a good complement to existing helix-stabilizing methods. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mobile Element Evolution Playing Jigsaw—SINEs in Gastropod and Bivalve Mollusks

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Matetovici, Irina; Sajgo, Szilard; Ianc, Bianca; Ochis, Cornelia; Bulzu, Paul; Popescu, Octavian; Damert, Annette

2016-01-01

SINEs (Short INterspersed Elements) are widely distributed among eukaryotes. Some SINE families are organized in superfamilies characterized by a shared central domain. These central domains are conserved across species, classes, and even phyla. Here we report the identification of two novel such superfamilies in the genomes of gastropod and bivalve mollusks. The central conserved domain of the first superfamily is present in SINEs in Caenogastropoda and Vetigastropoda as well as in all four subclasses of Bivalvia. We designated the domain MESC (Romanian for MElc—snail and SCoica—mussel) because it appears to be restricted to snails and mussels. The second superfamily is restricted to Caenogastropoda. Its central conserved domain—Snail—is related to the Nin-DC domain. Furthermore, we provide evidence that a 40-bp subdomain of the SINE V-domain is conserved in SINEs in mollusks and arthropods. It is predicted to form a stable stem-loop structure that is preserved in the context of the overall SINE RNA secondary structure in invertebrates. Our analysis also recovered short retrotransposons with a Long INterspersed Element (LINE)-derived 5′ end. These share the body and/or the tail with transfer RNA (tRNA)-derived SINEs within and across species. Finally, we identified CORE SINEs in gastropods and bivalves—extending the distribution range of this superfamily. PMID:26739168

Temporal dynamics of gastropod fauna on subtidal sandy sediments of the Ensenada de Baiona (NW Iberian Peninsula)

Science.gov (United States)

Moreira, J.; Aldea, C.; Troncoso, J. S.

2010-12-01

The temporal variation of the gastropod fauna inhabiting sandy sediments of the Ensenada de Baiona (Galicia, Spain) was studied at three subtidal sites from February 1996 to February 1997 by means of quantitative sampling. A total of 5,463 individuals representing 51 gastropod species and 22 families were found. The family Pyramidellidae was the most diverse in number of species (11 species), followed by Rissoidae and Trochidae (4 species each). The dogwhelk, Nassarius reticulatus, and the rissoid snail, Rissoa parva, were the numerically dominant species at the three studied sites; those and other abundant species showed their greatest densities by the end of summer and the beginning of autumn. In general, univariate measures of the assemblage (number of species, abundance, diversity and evenness) showed variations through time; greater values were recorded between summer and autumn depending on the site. Multivariate analyses done on abundance data showed certain seasonality in the evolution of the assemblage as expected for shallow subtidal sandy sediments at temperate latitudes; those seasonal changes were mostly related to variations in abundance of numerically dominant species. Although the measured sedimentary variables did not show significant correlations with faunal univariate parameters, sediment heterogeneity due to the presence of mats of Zostera marina L. and shells of dead bivalves might explain the differences in composition of the gastropod assemblage among sampling sites.

On the helix equation

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Taouil Hajer

2012-08-01

Full Text Available This paper is devoted to the helices processes, i.e. the solutions H : ℝ × Ω → ℝd, (t, ω ↦ H(t, ω of the helix equation egin{eqnarray} H(0,o=0; quad H(s+t,o= H(s,Phi(t,o +H(t,oonumber end{eqnarray} H ( 0 ,ω = 0 ;   H ( s + t,ω = H ( s, Φ ( t,ω + H ( t,ω where Φ : ℝ × Ω → Ω, (t, ω ↦ Φ(t, ω is a dynamical system on a measurable space (Ω, ℱ. More precisely, we investigate dominated solutions and non differentiable solutions of the helix equation. For the last case, the Wiener helix plays a fundamental role. Moreover, some relations with the cocycle equation defined by Φ, are investigated. Ce papier est consacré aux hélices, c’est-à-dire les solutions H : ℝ × Ω → ℝd, (t, ω ↦ H(t, ω de l’équation fonctionnelle egin{eqnarray} H(0,o=0; quad H(s+t,o= H(s,Phi(t,o +H(t,o onumber end{eqnarray} H ( 0 ,ω = 0 ;   H ( s + t,ω = H ( s, Φ ( t,ω + H ( t,ω où Φ : ℝ × Ω → Ω, (t, ω ↦ Φ(t, ω est un système dynamique défini sur un espace mesurable (Ω, ℱ. Plus présisément, nous déterminons d’abord les hélices dominées puis nous caractérisons les hélices non différentiables. Dans ce dernier cas, l’hélice de Wiener joue un rôle important. Nous précisons aussi quelques relations des hélices avec les cocycles définis par Φ.

Genome-wide identification and analysis of the chicken basic helix-loop-helix factors.

Science.gov (United States)

Liu, Wu-Yi; Zhao, Chun-Jiang

2010-01-01

Members of the basic helix-loop-helix (bHLH) family of transcription factors play important roles in a wide range of developmental processes. In this study, we conducted a genome-wide survey using the chicken (Gallus gallus) genomic database, and identified 104 bHLH sequences belonging to 42 gene families in an effort to characterize the chicken bHLH transcription factor family. Phylogenetic analyses revealed that chicken has 50, 21, 15, 4, 8, and 3 bHLH members in groups A, B, C, D, E, and F, respectively, while three members belonging to none of these groups were classified as ''orphans". A comparison between chicken and human bHLH repertoires suggested that both organisms have a number of lineage-specific bHLH members in the proteomes. Chromosome distribution patterns and phylogenetic analyses strongly suggest that the bHLH members should have arisen through gene duplication at an early date. Gene Ontology (GO) enrichment statistics showed 51 top GO annotations of biological processes counted in the frequency. The present study deepens our understanding of the chicken bHLH transcription factor family and provides much useful information for further studies using chicken as a model system.

A genome-wide survey on basic helix-loop-helix transcription factors in giant panda.

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Chunwang Dang

Full Text Available The giant panda (Ailuropoda melanoleuca is a critically endangered mammalian species. Studies on functions of regulatory proteins involved in developmental processes would facilitate understanding of specific behavior in giant panda. The basic helix-loop-helix (bHLH proteins play essential roles in a wide range of developmental processes in higher organisms. bHLH family members have been identified in over 20 organisms, including fruit fly, zebrafish, mouse and human. Our present study identified 107 bHLH family members being encoded in giant panda genome. Phylogenetic analyses revealed that they belong to 44 bHLH families with 46, 25, 15, 4, 11 and 3 members in group A, B, C, D, E and F, respectively, while the remaining 3 members were assigned into "orphan". Compared to mouse, the giant panda does not encode seven bHLH proteins namely Beta3a, Mesp2, Sclerax, S-Myc, Hes5 (or Hes6, EBF4 and Orphan 1. These results provide useful background information for future studies on structure and function of bHLH proteins in the regulation of giant panda development.

Organizing product innovation: hierarchy, market or triple-helix networks?

Science.gov (United States)

Fitjar, Rune Dahl; Gjelsvik, Martin; Rodríguez-Pose, Andrés

This paper assesses the extent to which the organization of the innovation effort in firms, as well as the geographical scale at which this effort is pursued, affects the capacity to benefit from product innovations. Three alternative modes of organization are studied: hierarchy, market and triple-helix-type networks. Furthermore, we consider triple-helix networks at three geographical scales: local, national and international. These relationships are tested on a random sample of 763 firms located in five urban regions of Norway which reported having introduced new products or services during the preceding 3 years. The analysis shows that firms exploiting internal hierarchy or triple-helix networks with a wide range of partners managed to derive a significantly higher share of their income from new products, compared to those that mainly relied on outsourcing within the market. In addition, the analysis shows that the geographical scale of cooperation in networks, as well as the type of partner used, matters for the capacity of firms to benefit from product innovation. In particular, firms that collaborate in international triple-helix-type networks involving suppliers, customers and R&D institutions extract a higher share of their income from product innovations, regardless of whether they organize the processes internally or through the network.

Terrestrial cooling in Northern Europe during the Eocene–Oligocene transition

Science.gov (United States)

Hren, Michael T.; Sheldon, Nathan D.; Grimes, Stephen T.; Collinson, Margaret E.; Hooker, Jerry J.; Bugler, Melanie; Lohmann, Kyger C.

2013-01-01

Geochemical and modeling studies suggest that the transition from the “greenhouse” state of the Late Eocene to the “icehouse” conditions of the Oligocene 34–33.5 Ma was triggered by a reduction of atmospheric pCO2 that enabled the rapid buildup of a permanent ice sheet on the Antarctic continent. Marine records show that the drop in pCO2 during this interval was accompanied by a significant decline in high-latitude sea surface and deep ocean temperature and enhanced seasonality in middle and high latitudes. However, terrestrial records of this climate transition show heterogeneous responses to changing pCO2 and ocean temperatures, with some records showing a significant time lag in the temperature response to declining pCO2. We measured the Δ47 of aragonite shells of the freshwater gastropod Viviparus lentus from the Solent Group, Hampshire Basin, United Kingdom, to reconstruct terrestrial temperature and hydrologic change in the North Atlantic region during the Eocene–Oligocene transition. Our data show a decrease in growing-season surface water temperatures (∼10 °C) during the Eocene–Oligocene transition, corresponding to an average decrease in mean annual air temperature of ∼4–6 °C from the Late Eocene to Early Oligocene. The magnitude of cooling is similar to observed decreases in North Atlantic sea surface temperature over this interval and occurs during major glacial expansion. This suggests a close linkage between atmospheric carbon dioxide concentrations, Northern Hemisphere temperature, and expansion of the Antarctic ice sheets. PMID:23610424

Population structure of an invasive parthenogenetic gastropod in coastal lakes and estuaries of northern KwaZulu-Natal, South Africa.

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Nelson A F Miranda

Full Text Available BACKGROUND: Estuaries and coastal lakes receive little attention despite being heavily invaded by non-indigenous invasive species (NIS. In these situations, studies of population dynamics in invaded habitats can provide valuable insights into how NIS interact with new environments. Tarebia granifera is a prosobranch gastropod from south-east Asia which has invaded other sub-tropical parts of the world. This study addresses whether a small number of key environmental factors influences gastropod communities, and specifically how the population density and size structure of T. granifera were influenced by environmental change in estuaries and coastal lakes in southern Africa. METHODOLOGY/PRINCIPAL FINDINGS: T. granifera's density, number of brooded juveniles and size structure were measured at the St. Lucia Estuary, Mgobozeleni Estuary, Lake Sibaya and Lake Nhlange. Size structure was classified according to shell height (SH. All dissected individuals were found to be female and free from trematode infection. Salinity, water depth, temperature, and pH were the main factors correlated with population density of gastropod communities. T. granifera often reached densities well over 1000 ind. m(-2, displacing indigenous gastropods and becoming a dominant component of the benthic community. T. granifera successfully invaded estuaries despite frequent exposure to high salinity and desiccation, which could together eliminate >97% of the population. The persistence of T. granifera was ensured due to its high fecundity and the environmental tolerance of large adults (20-30 mm SH which carried an average of 158±12.8 SD brooded juveniles. Repeat introductions were not essential for the success of this parthenogenetic NIS. CONCLUSION/SIGNIFICANCE: There is a need for a broader study on the reproductive biology of T. granifera (including the previously overlooked "brood pouch ecology", which affects population dynamics and may be relevant to other

Reconstruction of Regional Environments in the Caribbean During the Neogene Using Gastropod Stable Isotope Profiles

Science.gov (United States)

Robbins, J. A.; Grossman, E. L.; O'Dea, A.; Tao, K.

2011-12-01

The closure of the Central American Isthmus (CAI) ca. 3.8-3.6 Ma triggered changes in nearshore environments in the Caribbean, causing changes in marine annual range of temperature (MART), carbonate deposition, and the benthic ecosystem. The associated extinction event began ca. 3-2 Ma, peaking between 2-1 Ma. More than two dozen "faunules", discreet packages of fauna which lived under similar environmental conditions, represent time just prior to, during, and after the uplift of the CAI. Multiple parameters including the amount and types of fauna present in each faunule have been used to estimate factors such as paleodepth, MART, extinction rates, and changes in ecological structure over time. Oxygen and carbon isotope analyses (δ18O and δ13C) of gastropod shells serially-sampled about the spire provide records of seasonal environmental conditions. In the tropics, gastropods that live under conditions of strong seasonal upwelling and freshwater input have a greater range of δ18O values in their profiles compared to those animals that live in non-upwelling waters with little freshwater input. Low δ13C values often represent the isotopically low terrestrial carbon found in river runoff, and may be coupled with low δ18O values during seasonal freshening of marine waters. Preliminary data from Strombus shells representing four faunules ranging in age from before the rise of the isthmus through its completion demonstrate the effectiveness of using these mollusks to study ancient tropical environments. Rio Limoncito (~3 Ma), which is believed to represent water depths of 20-40m based on foraminiferal assemblage, yielded the lowest δ18O values (-0.6±0.4%, representing the warmest temperatures/lowest salinities). The samples from Pueblo Nuevo (~1.6 Ma), with an estimated paleodepth between 50 and 100m, had an average value of 0.4±0.3% and therefore represent cooler waters/higher salinity. A shell from NE Escudo de Veraguas (~3.55 Ma) shows a shift from essentially

Double helix vortex breakdown in a turbulent swirling annular jet flow

NARCIS (Netherlands)

Vanierschot, M.; Perçin, M.; van Oudheusden, B.W.

2018-01-01

In this paper, we report on the structure and dynamics of double helix vortex breakdown in a turbulent annular swirling jet. Double helix breakdown has been reported previously for the laminar flow regime, but this structure has rarely been observed in turbulent flow. The flow field is

The River Valleys as Biodiversity Reservoirs for Land Snails in Highly Anthropic Areas – The Case of Cisnădie River (Romania

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Gheoca Voichiţa

2016-12-01

Full Text Available This study focuses on the snail fauna of a river valley passing through two closely located settlements. Thirty six species of terrestrial gastropods were identified. Species such as Macrogastra borealis, Alinda fallax, Alinda viridana, Bulgarica vetusta, Monachoides vicinus, Drobacia banatica, are present along the river and abundant in the sampling stations downstream of Cisnădie town. The high specific diversity and the presence of typical forest species demonstrate the presence of fragments of habitat that can preserve populations of terrestrial gastropods, underlining the importance of river valleys in conservation and dispersion of these species.

Unraveling the Role of the C-terminal Helix Turn Helix of the Coat-binding Domain of Bacteriophage P22 Scaffolding Protein*

Science.gov (United States)

Padilla-Meier, G. Pauline; Gilcrease, Eddie B.; Weigele, Peter R.; Cortines, Juliana R.; Siegel, Molly; Leavitt, Justin C.; Teschke, Carolyn M.; Casjens, Sherwood R.

2012-01-01

Many viruses encode scaffolding and coat proteins that co-assemble to form procapsids, which are transient precursor structures leading to progeny virions. In bacteriophage P22, the association of scaffolding and coat proteins is mediated mainly by ionic interactions. The coat protein-binding domain of scaffolding protein is a helix turn helix structure near the C terminus with a high number of charged surface residues. Residues Arg-293 and Lys-296 are particularly important for coat protein binding. The two helices contact each other through hydrophobic side chains. In this study, substitution of the residues of the interface between the helices, and the residues in the β-turn, by aspartic acid was used examine the importance of the conformation of the domain in coat binding. These replacements strongly affected the ability of the scaffolding protein to interact with coat protein. The severity of the defect in the association of scaffolding protein to coat protein was dependent on location, with substitutions at residues in the turn and helix 2 causing the most significant effects. Substituting aspartic acid for hydrophobic interface residues dramatically perturbs the stability of the structure, but similar substitutions in the turn had much less effect on the integrity of this domain, as determined by circular dichroism. We propose that the binding of scaffolding protein to coat protein is dependent on angle of the β-turn and the orientation of the charged surface on helix 2. Surprisingly, formation of the highly complex procapsid structure depends on a relatively simple interaction. PMID:22879595

Bioactive potential of some economically important marine gastropods along the Gulf of Mannar region, southeast coast of India

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JayanthiGovindarajalu

2016-08-01

Full Text Available Objective: To analyse the economically important gastropods for prospective antimicrobial, antioxidant and cytotoxic activities from the Gulf of Mannar region, southeast coast of India. Methods: The bioactive potential of some gastropods i.e. Babylonia spirata (B. spirata, Phalium glaucum, Tonna dolium, Hemifusus pugilinus, Xancus pyrum, Chicoreus ramosus (C. ramosus, Harpa articularis, Ficus ficus and Babylonia zeylanica were analysed. Antimicrobial activity was carried out against 8 human pathogenic bacteria and 3 fungal strains by well diffusion method. Antioxidant and cytotoxic activities were analyzed by standard methods. Results: In antibacterial and antifungal activities, methanolic extract of B. spirata significantly showed the highest inhibition zone against Aeromonas hydrophila and Fusarium spp. (P > 0.05. In the total antioxidant activity, the maximum activity was observed in B. spirata (510 µg/mg and in the 1.1-diphenyl-2-picrylhydrazyl scavenging activity, B. spirata showed the highest percentage of inhibition (76.7%. In the case of cytotoxicity i.e. brine shrimp lethality tests the methanolic extract of C. ramosus showed the lowest percentage of mortality and the LC50 values were found to be 523.9 µg/mL. Conclusions: The results revealed that all the gastropods in the present study possessed antimicrobial, antioxidant and cytotoxic effects. However, species like B. spirata and C. ramosus exhibited potent activity and can be used for further clinical studies.

Genome-Wide Identification and Analysis of the Chicken Basic Helix-Loop-Helix Factors

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Wu-yi Liu

2010-01-01

Full Text Available Members of the basic helix-loop-helix (bHLH family of transcription factors play important roles in a wide range of developmental processes. In this study, we conducted a genome-wide survey using the chicken (Gallus gallus genomic database, and identified 104 bHLH sequences belonging to 42 gene families in an effort to characterize the chicken bHLH transcription factor family. Phylogenetic analyses revealed that chicken has 50, 21, 15, 4, 8, and 3 bHLH members in groups A, B, C, D, E, and F, respectively, while three members belonging to none of these groups were classified as ‘‘orphans’’. A comparison between chicken and human bHLH repertoires suggested that both organisms have a number of lineage-specific bHLH members in the proteomes. Chromosome distribution patterns and phylogenetic analyses strongly suggest that the bHLH members should have arisen through gene duplication at an early date. Gene Ontology (GO enrichment statistics showed 51 top GO annotations of biological processes counted in the frequency. The present study deepens our understanding of the chicken bHLH transcription factor family and provides much useful information for further studies using chicken as a model system.

Mobile Element Evolution Playing Jigsaw - SINEs in Gastropod and Bivalve Mollusks.

Science.gov (United States)

Matetovici, Irina; Sajgo, Szilard; Ianc, Bianca; Ochis, Cornelia; Bulzu, Paul; Popescu, Octavian; Damert, Annette

2016-01-06

SINEs (Short INterspersed Elements) are widely distributed among eukaryotes. Some SINE families are organized in superfamilies characterized by a shared central domain. These central domains are conserved across species, classes, and even phyla. Here we report the identification of two novel such superfamilies in the genomes of gastropod and bivalve mollusks. The central conserved domain of the first superfamily is present in SINEs in Caenogastropoda and Vetigastropoda as well as in all four subclasses of Bivalvia. We designated the domain MESC (Romanian for MElc-snail and SCoica-mussel) because it appears to be restricted to snails and mussels. The second superfamily is restricted to Caenogastropoda. Its central conserved domain-Snail-is related to the Nin-DC domain. Furthermore, we provide evidence that a 40-bp subdomain of the SINE V-domain is conserved in SINEs in mollusks and arthropods. It is predicted to form a stable stem-loop structure that is preserved in the context of the overall SINE RNA secondary structure in invertebrates. Our analysis also recovered short retrotransposons with a Long INterspersed Element (LINE)-derived 5' end. These share the body and/or the tail with transfer RNA (tRNA)-derived SINEs within and across species. Finally, we identified CORE SINEs in gastropods and bivalves-extending the distribution range of this superfamily. © The Author(s) 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Gastropod-derived haemocyte extracellular traps entrap metastrongyloid larval stages of Angiostrongylus vasorum, Aelurostrongylus abstrusus and Troglostrongylus brevior

DEFF Research Database (Denmark)

Lange, Malin K.; Penagos-Tabares, Felipe; Munoz-Caro, Tamara

2017-01-01

Background Phagocyte-derived extracellular traps (ETs) were recently demonstrated mainly in vertebrate hosts as an important effector mechanism against invading parasites. In the present study we aimed to characterize gastropod-derived invertebrate extracellular phagocyte trap (InEPT) formation i...

The Discovery of the Double Helix

CERN Multimedia

CERN. Geneva

2011-01-01

Professor James D. Watson has kindly agreed to make a presentation on the 1953 finding of the Double Helix at the Cavendish Laboratory by Francis Crick and himself. Being one of the greatest scientific discoveries in human history, little else needs to be added.

A study on the diversity of gastropods in Hormuz Island with first record of two species from the Iranian coast of the Persian Gulf

Directory of Open Access Journals (Sweden)

Nabiallah Kheirabadi

2014-04-01

Full Text Available This study was carried out to determine the diversity of gastropod species in the intertidal zone of Hormuz Island in the Persian Gulf. Seasonal sampling was conducted in 7 selected sites by throwing nine random quadrates (0.5×0.5 m in each site. Samples of each site were separately transferred to the laboratory and identified by the standard keys and verified by the Conchology Museum of Tokyo University of Science. Forty -nine gastropod species were identified, from which 2 species, Turicula nelliae and Linatella caudata were recorded for the first time from the Iranian coast of the Persian Gulf. The highest number of gastropods in one site was 28 species in site 1 (East of Marine Research Center, Also highest number of gastropods in one season was 35 species in winter and lowest number was in 28 species in summer. Simpson dominance index, Shannon-Wiener species diversity index, Margalef richness index and evenness index were calculated in the different sites and results showed that site 1 contained the most amount of the Shannon-Wiener and Margalef indices and site 6 (West of Island contained the most amount of the Simpson index. Also, site 3 (Mangrove forest showed the lowest amount of the Simpson, Shannon-Wiener and Margalef indices, while maximum amount of evenness index occurred in this site.

Modulating Transmembrane α-Helix Interactions through pH-Sensitive Boundary Residues.

Science.gov (United States)

Ng, Derek P; Deber, Charles M

2016-08-09

Changes in pH can alter the structure and activity of proteins and may be used by the cell to control molecular function. This coupling can also be used in non-native applications through the design of pH-sensitive biomolecules. For example, the pH (low) insertion peptide (pHLIP) can spontaneously insert into a lipid bilayer when the pH decreases. We have previously shown that the α-helicity and helix-helix interactions of the TM2 α-helix of the proteolipid protein (PLP) are sensitive to the local hydrophobicity at its C-terminus. Given that there is an ionizable residue (Glu-88) at the C-terminus of this transmembrane (TM) segment, we hypothesized that changing the ionization state of this residue through pH may alter the local hydrophobicity of the peptide enough to affect both its secondary structure and helix-helix interactions. To examine this phenomenon, we synthesized peptide analogues of the PLP TM2 α-helix (wild-type sequence (66)AFQYVIYGTASFFFLYGALLLAEGF(90)). Using circular dichroism and Förster resonance energy transfer in the membrane-mimetic detergent sodium dodecyl sulfate, we found that a decrease in pH increases both peptide α-helicity and the extent of self-association. This pH-dependent effect is due specifically to the presence of Glu-88 at the C-terminus. Additional experiments in which Phe-90 was mutated to residues of varying hydrophobicities indicated that the strength of this effect is dependent on the local hydrophobicity near Glu-88. Our results have implications for the design of TM peptide switches and improve our understanding of how membrane protein structure and activity can be regulated through local molecular environmental changes.

Evaluating a 5-year metal contamination remediation and the biomonitoring potential of a freshwater gastropod along the Xiangjiang River, China.

Science.gov (United States)

Li, Deliang; Pi, Jie; Zhang, Ting; Tan, Xiang; Fraser, Dylan J

2018-05-16

Effective remediation of heavy metal pollution in aquatic systems is desired in many regions, but it requires integrative assessments of sediments, water, and biota that can serve as robust biomonitors. We assessed the effects of a 5-year metal contamination remediation along the Xiangjiang River, China, by comparing concentrations of trace metals in water and surface sediments between 2010-2011 and 2016. We also explored the trace metal biomonitoring potential of a freshwater gastropod (Bellamya aeruginosa). Metal concentrations in water (means and ranges) dropped over time to within permissible limits of drinking water guidelines set by China, USEPA, and WHO in 2016. Although sediment means and ranges of Cd, Pb, Zn, and Mn also diminished with remediation, those for Cr and Cu slightly increased, and all six metals retained concentrations higher than standards set by China. All metals in sediments could also be associated with anthropogenic inputs using a hierarchical clustering analysis, and they generate high potential ecological risks based on several indices, especially for Cd and As. The bio-sediment accumulation factors of all measured trace metals in gastropod soft tissues and shells were lower than 1.0, except for Ca. Trace metal contents in gastropods were positively correlated with those in water and surface sediments for As (soft tissues) and Cr (shells). Collectively, our results do not yet highlight strong beneficial effects of 5-year remediation and clearly illustrate the heavy metal pollution remaining in Xiangjiang River sediment. Additional physical, chemical, and biological measurements should be implemented to improve sediment quality. We further conclude that gastropod soft tissues and shells can be suitable biomonitors of spatial differences in some heavy metals found within river sediments (e.g., As, Cr).

Gastropod growth and survival as bioindicators of stress associated with high nutrients in the intertidal of a shallow temperate estuary

Science.gov (United States)

Marsden, Islay D.; Baharuddin, Nursalwa

2015-04-01

The effects of multiple stressors on estuarine organisms are not well understood. Using cage experiments we measured the survival and growth of the pulmonate gastropod Amphibola crenata at five locations which differed contaminant levels. Water nutrients came from a nearby sewage treatment works and the sediment contained low levels of trace metals. Over 6 weeks of exposure, sediment surface chlorophyll levels varied amongst locations. The Chl a values were positively correlated with sediment N and P and trace metals As, Cd, Cu, Pb and Zn. Pulmonate survival depended on location, highest mortality was from a site close to the treatment plant and mortality rate of large individuals decreased significantly with distance away from it. For four locations, medium A. crenata had higher survival than small (juveniles) or adults. Growth rates of small individuals exceeded those for medium and large A. crenata. The mean length increment/week for medium gastropods ranged between 0.49 and 1.11 mm and was negatively correlated with the amount of Chl a in the surface sediment, suggesting the negative effects of eutrophication on gastropod growth. Growth rate of the pulmonate was not correlated with nutrient concentration or trace metal concentrations in the sediment. The dry weight condition index (CI) did not correlate with the growth rate, and for medium individuals, was unaffected by any of the environmental variables. The CI of small individuals was negatively affected by increasing water nutrient levels and the CI of large individuals negatively affected by increasing sediment nutrients and trace metal concentrations. The results from this study suggest that gastropod growth and survival could be used as tools to monitor the effects of changing nutrient levels and recovery from eutrophication within temperate estuaries.

Non-Random Sibling Cannibalism in the Marine Gastropod Crepidula coquimbensis.

Directory of Open Access Journals (Sweden)

Antonio Brante

Full Text Available Sibling cannibalism is commonly observed in marine species. For instance, intrabrood cannibalism has been documented in marine gastropods with direct development, suggesting a relationship between embryo behavior and the evolution of life history strategies. However, there has been little effort to document the factors driving sibling cannibalism in marine species. The kin selection theory suggests that the level of relatedness plays an important role in cannibalism patterns. We examined Crepidula coquimbensis, a marine gastropod that broods and encloses its brooded offspring in capsules. Encapsulated embryos show sibling cannibalism and high levels of intracapsular multiple paternity. Given these features, cannibalistic behavior may be driven by kin-relatedness. To test this hypothesis, we constructed artificial aggregations of embryos to mimic three levels of relatedness: high, medium and low. For each category of aggregation, the cannibalism rate and benefits (i.e. size at hatching of surviving offspring were estimated. In addition, at the end of embryo development, we performed parentage analyses to determine if cannibalism was associated with the relatedness between cannibal and victim embryos. Our results show that the intensity of sibling cannibalism increased in aggregations characterized by the lowest level of relatedness. There were important benefits of cannibalism in terms of hatching cannibal size. In addition, cannibalism between embryos was not random: the variation in reproductive success between males increased over the course of the experiment and the effective number of fathers decreased. Altogether, these results suggest that polyandry may play an important role in the evolution of sibling cannibalism in C. coquimbensis and that kin selection may operate during early embryonic stages in this species.

Exploring the membrane fusion mechanism through force-induced disassembly of HIV-1 six-helix bundle

Energy Technology Data Exchange (ETDEWEB)

Gao, Kai [Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China); Beijing Key Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhang, Yong [Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China); Beijing Key Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China); Lou, Jizhong, E-mail: jlou@ibp.ac.cn [Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China); Beijing Key Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China)

2016-05-13

Enveloped virus, such as HIV-1, employs membrane fusion mechanism to invade into host cell. HIV-1 gp41 ectodomain uses six-helix bundle configuration to accomplish this process. Using molecular dynamic simulations, we confirmed the stability of this six-helix bundle by showing high occupancy of hydrogen bonds and hydrophobic interactions. Key residues and interactions important for the bundle integration were characterized by force-induced unfolding simulations of six-helix bundle, exhibiting the collapse order of these groups of interactions. Moreover, our results in some way concerted with a previous theory that the formation of coiled-coil choose a route which involved cooperative interactions between the N-terminal and C-terminal helix. -- Highlights: •Unfolding of HIV-1 gp41 six-helix bundle is studied by molecular dynamics simulations. •Specific interactions responsible for the stability of HIV-1 envelope post-fusion conformation were identified. •The gp41 six-helix bundle transition inducing membrane fusion might be a cooperative process of the three subunits.

Inter- and intra-specific variability in δ13C and δ18O values of freshwater gastropod shells from Lake Lednica, western Poland

Science.gov (United States)

Apolinarska, Karina; Pełechaty, Mariusz

2017-09-01

This study focuses on the inter- and intra-specific variability in δ13C and δ18O values of shells and opercula of gastropods sampled live from the littoral zone of Lake Lednica, western Poland. The δ13C and δ18O values were measured in individual opercula of Bithynia tentaculata and in shells of Bithynia tentaculata, Gyraulus albus, Gyraulus crista, Lymnaea sp., Physa fontinalis, Radix auricularia, Theodoxus fluviatilis and Valvata cristata. The gastropods selected for the study are among the species most commonly found in European Quaternary lacustrine sediments. The carbon isotope composition of the gastropod shells was species-specific and the same order of species from the most to the least 13C-depleted was observed at all sites sampled. Differences in shell δ13C values between species were similar at all sampling sites, thus the factors influencing shell isotopic composition were interpreted as species-specific. The δ18O values of shells were similar in all the species investigated. Significant intra-specific variability in shell δ13C and δ18O values was observed not only within the populations of Lake Lednica, which can be explained by heterogeneity of δ13C DIC, δ18O water and water temperature between the sites where macrophytes with snails attached were sampled, but also between individuals sampled from restricted areas of the lake's bottom. The latter points to the importance of factors related to the ontogeny of individual gastropods.

Freshwater gastropods in the Northern littoral mesoregion of Espírito Santo, Brazil

Directory of Open Access Journals (Sweden)

Marco Antônio Andrade de Souza

2017-09-01

Full Text Available Studies on the distribution of molluscs in Brazilhave been conducted since the beginning of the twentieth and the knowledge of the species distributed in the country represent important findings, which contribute to the understanding of human diseases and those of veterinary importance, transmitted by them. In order to verify the distribution of freshwater gastropods in Espírito Santo, a malacological surveywas carried out in nine municipalities that comprise the Northern mesoregion of the State, between January 2010 and February 2015. Initially the water collections occurring in the municipality were verified and the lotic systems at different levels of use and conservation were determined. Molluscs were collected monthly using a hand net adapted to a stick steel. An individual sample effort of 30 minutes was applied, by scanning, at about ten meters in each one of the selected habitats. A total of 6,000 specimens were collected, represented by genera Melanoides, Drepanotrema, Physa, Biomphalaria and Pomacea. Among the molluscs, some specimens were positive for flatworm larvae of medical and veterinary importance. The results contributed to the knowledge of the current distribution of freshwater gastropods in the Northern region of Espírito Santo whose the only record for the region dates back to 1983.

FPGA helix tracking algorithm for PANDA

Energy Technology Data Exchange (ETDEWEB)

Liang, Yutie; Galuska, Martin; Gessler, Thomas; Kuehn, Wolfgang; Lange, Jens Soeren; Muenchow, David; Spruck, Bjoern [II. Physikalisches Institut, Giessen University (Germany); Ye, Hua [Institute of High Energy Physics, Beijing (China); Collaboration: PANDA-Collaboration

2015-07-01

The PANDA detector is a general-purpose detector for physics with high luminosity cooled antiproton beams, planed to operate at the FAIR facility in Darmstadt, Germany. The central detector includes a silicon Micro Vertex Detector (MVD) and a Straw Tube Tracker (STT). Without any hardware trigger, large amounts of raw data are streaming into the data acquisition system. The data reduction task is performed in the online system by reconstruction algorithms programmed on FPGAs (Field Programmable Gate Arrays) as first level and on a farm of GPUs or PCs as a second level. One important part in the system is the online track reconstruction. In this presentation, an online tracking algorithm for helix tracking reconstruction in the solenoidal field is shown. The tracking algorithm is composed by two parts, a road finding module followed by an iterative helix parameter calculation module. A performance study using C++ and the status of the VHDL implementation are presented.

Intersegment interactions and helix-coil transition within the generalized model of polypeptide chains approach

Science.gov (United States)

Badasyan, A. V.; Hayrapetyan, G. N.; Tonoyan, Sh. A.; Mamasakhlisov, Y. Sh.; Benight, A. S.; Morozov, V. F.

2009-09-01

The generalized model of polypeptide chains is extended to describe the helix-coil transition in a system comprised of two chains interacting side-by-side. The Hamiltonian of the model takes into account four possible types of interactions between repeated units of the two chains, i.e., helix-helix, helix-coil, coil-helix, and coil-coil. Analysis reveals when the energy Ihh+Icc of (h-h, c-c) interactions overwhelms the energy Ihc+Ich of mixed (h-c, c-h) interactions, the correlation length rises substantially, resulting in narrowing of the transition interval. In the opposite case, when Ihh+Icchelix formation and disfavored intersegment interactions from the same theoretical perspective.

Regulation of TCF ETS-domain transcription factors by helix-loop-helix motifs.

Science.gov (United States)

Stinson, Julie; Inoue, Toshiaki; Yates, Paula; Clancy, Anne; Norton, John D; Sharrocks, Andrew D

2003-08-15

DNA binding by the ternary complex factor (TCF) subfamily of ETS-domain transcription factors is tightly regulated by intramolecular and intermolecular interactions. The helix-loop-helix (HLH)-containing Id proteins are trans-acting negative regulators of DNA binding by the TCFs. In the TCF, SAP-2/Net/ERP, intramolecular inhibition of DNA binding is promoted by the cis-acting NID region that also contains an HLH-like motif. The NID also acts as a transcriptional repression domain. Here, we have studied the role of HLH motifs in regulating DNA binding and transcription by the TCF protein SAP-1 and how Cdk-mediated phosphorylation affects the inhibitory activity of the Id proteins towards the TCFs. We demonstrate that the NID region of SAP-1 is an autoinhibitory motif that acts to inhibit DNA binding and also functions as a transcription repression domain. This region can be functionally replaced by fusion of Id proteins to SAP-1, whereby the Id moiety then acts to repress DNA binding in cis. Phosphorylation of the Ids by cyclin-Cdk complexes results in reduction in protein-protein interactions between the Ids and TCFs and relief of their DNA-binding inhibitory activity. In revealing distinct mechanisms through which HLH motifs modulate the activity of TCFs, our results therefore provide further insight into the role of HLH motifs in regulating TCF function and how the inhibitory properties of the trans-acting Id HLH proteins are themselves regulated by phosphorylation.

Selective intercalation of six ligands molecules in a self-assembled triple helix

NARCIS (Netherlands)

Mateos timoneda, Miguel; Kerckhoffs, J.M.C.A.; Reinhoudt, David; Crego Calama, Mercedes

2007-01-01

The addition of a ligand molecule to an artificial self-assembled triple helix leads to the selective intercalation of two hydrogen-bonded trimers in specific binding pockets. Furthermore, the triple helix suffers large conformational rearrangements in order to accommodate the ligand molecules in a

Thermal helix-coil transition in UV irradiated collagen from rat tail tendon.

Science.gov (United States)

Sionkowska, A; Kamińska, A

1999-05-01

The thermal helix-coil transition in UV irradiated collagen solution, collagen film and pieces of rat tail tendon (RTT) were compared. Their thermal stability's were determined by differential scanning calorimeter (DSC) and by viscometric measurements. The denaturation temperatures of collagen solution, film and pieces of RTT were different. The helix-coil transition occur near 40 degrees C in collagen solution, near 112 degrees C in collagen film, and near 101 degrees C in pieces of RTT. After UV irradiation the thermal helix-coil transition of collagen samples were changed. These changes depend on the degree of hydratation.

Mass mortality of the vermetid gastropod Ceraesignum maximum

Science.gov (United States)

Brown, A. L.; Frazer, T. K.; Shima, J. S.; Osenberg, C. W.

2016-09-01

Ceraesignum maximum (G.B. Sowerby I, 1825), formerly Dendropoma maximum, was subject to a sudden, massive die-off in the Society Islands, French Polynesia, in 2015. On Mo'orea, where we have detailed documentation of the die-off, these gastropods were previously found in densities up to 165 m-2. In July 2015, we surveyed shallow back reefs of Mo'orea before, during and after the die-off, documenting their swift decline. All censused populations incurred 100% mortality. Additional surveys and observations from Mo'orea, Tahiti, Bora Bora, and Huahine (but not Taha'a) suggested a similar, and approximately simultaneous, die-off. The cause(s) of this cataclysmic mass mortality are currently unknown. Given the previously documented negative effects of C. maximum on corals, we expect the die-off will have cascading effects on the reef community.

Triple helix interactions for eco-innovation

DEFF Research Database (Denmark)

Hermann, Roberto Rivas; Riisgaard, Henrik; Remmen, Arne

the role of science parks in promoting eco-innovation. This study uses qualitative data gathered in two units of analysis: Panama Canal Authority and City of Knowledge Science Park. The study examines how Triple Helix interactions have built the regional system of eco-innovation at the Panama Canal...

Solitons in an isolated helix chain

DEFF Research Database (Denmark)

Christiansen, Peter Leth; Zolotaryuk, Alexander; Savin, A.V.

1997-01-01

as a generalization of the well-known one-dimensional Fermi-Pasta-Ulam model to include transverse degrees of freedom of the chain molecules. In the particular case of the alpha-helix molecular chain, the intermolecular interactions involved into the model are the point-point bonds connecting the first-, second...

Increasing sea surface temperature and range shifts of intertidal gastropods along the Iberian Peninsula

Science.gov (United States)

Rubal, Marcos; Veiga, Puri; Cacabelos, Eva; Moreira, Juan; Sousa-Pinto, Isabel

2013-03-01

There are well-documented changes in abundance and geographical range of intertidal invertebrates related to climate change at north Europe. However, the effect of sea surface warming on intertidal invertebrates has been poorly studied at lower latitudes. Here we analyze potential changes in the abundance patterns and distribution range of rocky intertidal gastropods related to climate change along the Iberian Peninsula. To achieve this aim, the spatial distribution and range of sub-tropical, warm- and cold-water species of intertidal gastropods was explored by a fully hierarchical sampling design considering four different spatial scales, i.e. from region (100 s of km apart) to quadrats (ms apart). Variability on their patterns of abundance was explored by analysis of variance, changes on their distribution ranges were detected by comparing with previous records and their relationship with sea water temperature was explored by rank correlation analyses. Mean values of sea surface temperature along the Iberian coast, between 1949 and 2010, were obtained from in situ data compiled for three different grid squares: south Portugal, north Portugal, and Galicia. Lusitanian species did not show significant correlation with sea water temperature or changes on their distributional range or abundance, along the temperature gradient considered. The sub-tropical species Siphonaria pectinata has, however, increased its distribution range while boreal cold-water species showed the opposite pattern. The latter was more evident for Littorina littorea that was almost absent from the studied rocky shores of the Iberian Peninsula. Sub-tropical and boreal species showed significant but opposite correlation with sea water temperature. We hypothesized that the energetic cost of frequent exposures to sub-lethal temperatures might be responsible for these shifts. Therefore, intertidal gastropods at the Atlantic Iberian Peninsula coast are responding to the effect of global warming as it

Democracy and environment as references for quadruple and quintuple helix innovation systems

Science.gov (United States)

Carayannis, Elias G.; Campbell, David F. J.; Orr, Barron J.

2015-04-01

The perspective of democracy and the ecological context define key references for knowledge production and innovation in innovation systems. Particularly under conditions of environmental change where enhancing the potential for adaptation is critical, this requires a closer look at ecological responsibility and sensitivity in the different innovation models and governance regimes. The "Quintuple Helix" innovation model is an approach that stresses the necessary socio-ecological transition of society and economy by adding an environment helix to an innovation system already made up of three (university-industry-government) or four (civil society relations) helices in a way that supports adaptation by incorporating global warming as both a challenge to and a driver of innovation. There is the proposition that knowledge production and innovation co-evolve with democracy (Carayannis and Campbell, 2014). In the Triple Helix model (Etzkowitz and Leydesdorff, 2000) the existence of a democracy does not appear to be necessary for knowledge production and innovation. However, the Quadruple Helix (Carayannis and Campbell, 2009, 2010 and 2014) is defined and represented by additional key attributes and components: "media-based and culture-based public", "civil society" and "arts, artistic research and arts-based innovation" (Bast, Carayannis and Campbell, 2015). Implications of this are that the fourth helix in the Quadruple Helix innovation systems brings in and represents the perspective of "dimension of democracy" or the "context of democracy" for knowledge in general and knowledge production and innovation in more particular. Within theories of democracy there is a competition between narrow and broader concepts of democracy (Campbell, 2013). This is particularly true when democracy is to be understood to transcend more substantially the narrow understanding of being primarily based on or being primarily rooted in government institutions (within a Triple Helix

Native and introduced gastropods in laurel forests on Tenerife, Canary Islands

Science.gov (United States)

Kappes, Heike; Delgado, Juan D.; Alonso, María R.; Ibáñez, Miguel

2009-09-01

The introduction of non-native gastropods on islands has repetitively been related to a decline of the endemic fauna. So far, no quantitative information is available even for the native gastropod fauna from the laurel forests (the so-called Laurisilva) of the Canary Islands. Much of the original laurel forest has been logged in recent centuries. Based on vegetation studies, we hypothesized that densities and the number of introduced species decline with the age of the regrowth forests. We sampled 27 sites from which we collected thirty native and seven introduced species. Two introduced species, Milax nigricans and Oxychilus alliarius, were previously not reported from the Canary Islands. Assemblage composition was mainly structured by disturbance history and altitude. Overall species richness was correlated with slope inclination, prevalence of rocky outcrops, amounts of woody debris and leaf litter depth. Densities were correlated with the depth of the litter layer and the extent of herb layer cover and laurel canopy cover. Introduced species occurred in 22 sites but were neither related to native species richness nor to the time that elapsed since forest regrowth. One introduced slug, Lehmannia valentiana, is already wide-spread, with densities strongly related to herb cover. Overall species richness seemed to be the outcome of invasibility, thus factors enhancing species richness likely also enhance invasibility. Although at present introduced species contribute to diversity, the potential competition between introduced slugs and the rich native semi-slug fauna, and the effects of introduced predatory snails ( Oxychilus spp. and Testacella maugei) warrant further monitoring.

Structure of bacteriophage [phi]29 head fibers has a supercoiled triple repeating helix-turn-helix motif

Energy Technology Data Exchange (ETDEWEB)

Xiang, Ye; Rossmann, Michael G. (Purdue)

2011-12-22

The tailed bacteriophage {phi}29 capsid is decorated with 55 fibers attached to quasi-3-fold symmetry positions. Each fiber is a homotrimer of gene product 8.5 (gp8.5) and consists of two major structural parts, a pseudohexagonal base and a protruding fibrous portion that is about 110 {angstrom} in length. The crystal structure of the C-terminal fibrous portion (residues 112-280) has been determined to a resolution of 1.6 {angstrom}. The structure is about 150 {angstrom} long and shows three distinct structural domains designated as head, neck, and stem. The stem region is a unique three-stranded helix-turn-helix supercoil that has not previously been described. When fitted into a cryoelectron microscope reconstruction of the virus, the head structure corresponded to a disconnected density at the distal end of the fiber and the neck structure was located in weak density connecting it to the fiber. Thin section studies of Bacillus subtilis cells infected with fibered or fiberless {phi}29 suggest that the fibers might enhance the attachment of the virions onto the host cell wall.

Some ecological aspects and potential threats to an intertidal gastropod, Umbonium vestiarium

Digital Repository Service at National Institute of Oceanography (India)

Sivadas, S.; Ingole, B.S.; Sen, A.

geographic range. Several trochid species such as, Umbonium costatum from Japan (Noda et al., 1995) and Astrea undosa from Mexico (Belmar- Perez et al., 1993) spawn twice a year. Incomplete spawning for a number of gastropods has been reported (Ramesh et al... and reproductive cycle of wavy turban snail (Astrea undosa Wood, 1828; Gastropoda: Turbinidae) in Bahai Tortugas, BCS. Anales del Instituto de Ciencias del Mary Limnologia Universidad Nacional Autonoma de Mexico, 18, 169–87 (1993). Berry, A.J. and Bin O. Zamri...

Structural and functional aspects of winged-helix domains at the core of transcription initiation complexes.

Science.gov (United States)

Teichmann, Martin; Dumay-Odelot, Hélène; Fribourg, Sébastien

2012-01-01

The winged helix (WH) domain is found in core components of transcription systems in eukaryotes and prokaryotes. It represents a sub-class of the helix-turn-helix motif. The WH domain participates in establishing protein-DNA and protein-protein-interactions. Here, we discuss possible explanations for the enrichment of this motif in transcription systems.

Optimized molecular dynamics force fields applied to the helix-coil transition of polypeptides.

Science.gov (United States)

Best, Robert B; Hummer, Gerhard

2009-07-02

Obtaining the correct balance of secondary structure propensities is a central priority in protein force-field development. Given that current force fields differ significantly in their alpha-helical propensities, a correction to match experimental results would be highly desirable. We have determined simple backbone energy corrections for two force fields to reproduce the fraction of helix measured in short peptides at 300 K. As validation, we show that the optimized force fields produce results in excellent agreement with nuclear magnetic resonance experiments for folded proteins and short peptides not used in the optimization. However, despite the agreement at ambient conditions, the dependence of the helix content on temperature is too weak, a problem shared with other force fields. A fit of the Lifson-Roig helix-coil theory shows that both the enthalpy and entropy of helix formation are too small: the helix extension parameter w agrees well with experiment, but its entropic and enthalpic components are both only about half the respective experimental estimates. Our structural and thermodynamic analyses point toward the physical origins of these shortcomings in current force fields, and suggest ways to address them in future force-field development.

Inactivation of colicin Y by intramembrane helix–helix interaction with its immunity protein

Czech Academy of Sciences Publication Activity Database

Šmajs, D.; Doležalová, M.; Macek, Pavel; Žídek, L.

2008-01-01

Roč. 275, č. 21 (2008), s. 5325-5331 ISSN 1742-464X Institutional research plan: CEZ:AV0Z50200510 Keywords : colicin immunity * colicin y * helix-helix interaction Subject RIV: CE - Biochemistry Impact factor: 3.139, year: 2008

PH4 of petunia is an R2R3-MYB protein that activates vacuolar acidification through interactions with Basic-Helix-Loop-Helix transcription factors of the anthocyanin pathway.

NARCIS (Netherlands)

Quattrocchio, F.M.; Verweij, C.W.; Spelt, C.E.; Mol, J.N.M.; Koes, R.E.

2007-01-01

The Petunia hybrids genes ANTHOCYANIN1 (AN1) and AN2 encode transcription factors with a basic-helix-loop-helix (BHLH) and a MYB domain, respectively, that are required for anthocyanin synthesis and acidification of the vacuole in petal cells. Mutation of PH4 results in a bluer flower color,

Determination of Acetylcholinesterase activities in marine gastropod (Morula granulata) as a biomarker of neurotoxic contaminants along the Goan coast.

Digital Repository Service at National Institute of Oceanography (India)

Sarkar, A.; Tegur, P.M.; Jana, S.; Rao, P.V.S.S.D.P.

diseases or even death. Hence it is considered as a suitable biomarker for detecting environmental pollution caused by the neurotoxic compounds. We have carried out experiments with marine gastropods (Morula granulate) at the selected sites, Arambol...

Evidence of trophic transfer of microcystins from the gastropod Lymnaea stagnalis to the fish Gasterosteus aculeatus.

Science.gov (United States)

Lance, Emilie; Petit, Anais; Sanchez, Wilfried; Paty, Christelle; Gérard, Claudia; Bormans, Myriam

2014-01-01

According to our previous results the gastropod Lymnaea stagnalis exposed to MC-producing cyanobacteria accumulates microcystins (MCs) both as free and covalently bound forms in its tissues, therefore representing a potential risk of MC transfer through the food web. This study demonstrates in a laboratory experiment the transfer of free and bound MCs from L. stagnalis intoxicated by MC-producing Planktothrix agardhii ingestion to the fish Gasterosteus aculeatus. Fish were fed during five days with digestive glands of L. stagnalis containing various concentrations of free and bound MCs, then with toxin-free digestive glands during a 5-day depuration period. MC accumulation was measured in gastropod digestive gland and in various fish organs (liver, muscle, kidney, and gills). The impact on fish was evaluated through detoxification enzyme (glutathion-S-transferase, glutathion peroxydase and superoxyde dismutase) activities, hepatic histopathology, and modifications in gill ventilation, feeding and locomotion. G. aculeatus ingestion rate was similar with intoxicated and toxin-free diet. Fish accumulated MCs (up to 3.96±0.14μgg -1 DW) in all organs and in decreasing order in liver, muscle, kidney and gills. Hepatic histopathology was moderate. Glutathion peroxydase was activated in gills during intoxication suggesting a slight reactive oxygen species production, but without any impact on gill ventilation. Intoxication via ingestion of MC-intoxicated snails impacted fish locomotion. Intoxicated fish remained significantly less mobile than controls during the intoxication period possibly due to a lower health condition, whereas they showed a greater mobility during the depuration period that might be related to an acute foraging for food. During depuration, MC elimination was total in gills and kidney, but partial in liver and muscle. Our results assess the MC transfer from gastropods to fish and the potential risk induced by bound MCs in the food web. Copyright �

Lysine as helix C-capping residue in a synthetic peptide.

Science.gov (United States)

Esposito, G; Dhanapal, B; Dumy, P; Varma, V; Mutter, M; Bodenhausen, G

1997-01-01

The structure of the synthetic peptide CH3CO(Leu-Ser-Leu-Leu-Leu-Ser-Leu)3Lys-NH2 in trifluoroethanol/water 60/40 (volume ratio) was characterized by two-dimensional nmr spectroscopy. The peptide, closely related to the amphiphilic helix models designed by W. F. De-Grado and co-workers to mimic protein ion channels [(1988) Science, Vol. 240, p. 1177-1181], folds into a regular helix spanning residues 1-20. Evidence for a helix C-terminal capping conformation, involving the terminal lysine residue, was observed from Overhauser effects and checked for consistency by restrained molecular dynamics simulations. The side-chain amino group of Lys22 forms a hydrogen bond with the carbonyl of Leu18, and the distorted helical geometry of the terminal dipeptide allows the inclusion of a water bridge between the backbone NH of the Lys22 residue and the carbonyls of Leu19 and Ser20.

Thermodynamic Effects of Replacements of Pro Residues in Helix Interiors of Maltose-Binding Protein

OpenAIRE

Prajapati, RS; Lingaraju, GM; Bacchawat, Kiran; Surolia, Avadhesha; Varadarajan, Raghavan

2003-01-01

Introduction of Pro residues into helix interiors results in protein destabilization. It is currently unclear if the converse substitution (i.e., replacement of Pro residues that naturally occur in helix interiors would be stabilizing). Maltose-binding protein is a large 370-amino acid protein that contains 21 Pro residues. Of these, three nonconserved residues (P48, P133, and P159) occur at helix interiors. Each of the residues was replaced with Ala and Ser. Stabilities were characterized by...

One Peptide Reveals the Two Faces of α-Helix Unfolding-Folding Dynamics.

Science.gov (United States)

Jesus, Catarina S H; Cruz, Pedro F; Arnaut, Luis G; Brito, Rui M M; Serpa, Carlos

2018-04-12

The understanding of fast folding dynamics of single α-helices comes mostly from studies on rationally designed peptides displaying sequences with high helical propensity. The folding/unfolding dynamics and energetics of α-helix conformations in naturally occurring peptides remains largely unexplored. Here we report the study of a protein fragment analogue of the C-peptide from bovine pancreatic ribonuclease-A, RN80, a 13-amino acid residue peptide that adopts a highly populated helical conformation in aqueous solution. 1 H NMR and CD structural studies of RN80 showed that α-helix formation displays a pH-dependent bell-shaped curve, with a maximum near pH 5, and a large decrease in helical content in alkaline pH. The main forces stabilizing this short α-helix were identified as a salt bridge formed between Glu-2 and Arg-10 and the cation-π interaction involving Tyr-8 and His-12. Thus, deprotonation of Glu-2 or protonation of His-12 are essential for the RN80 α-helix stability. In the present study, RN80 folding and unfolding were triggered by laser-induced pH jumps and detected by time-resolved photoacoustic calorimetry (PAC). The photoacid proton release, amino acid residue protonation, and unfolding/folding events occur at different time scales and were clearly distinguished using time-resolved PAC. The partial unfolding of the RN80 α-helix, due to protonation of Glu-2 and consequent breaking of the stabilizing salt bridge between Glu-2 and Arg-10, is characterized by a concentration-independent volume expansion in the sub-microsecond time range (0.8 mL mol -1 , 369 ns). This small volume expansion reports the cost of peptide backbone rehydration upon disruption of a solvent-exposed salt bridge, as well as backbone intrinsic expansion. On the other hand, RN80 α-helix folding triggered by His-12 protonation and subsequent formation of a cation-π interaction leads to a microsecond volume contraction (-6.0 mL mol -1 , ∼1.7 μs). The essential role of two

Conformational Diffusion and Helix Formation Kinetics

International Nuclear Information System (INIS)

Hummer, Gerhard; Garcia, Angel E.; Garde, Shekhar

2000-01-01

The time, temperature, and sequence dependences of helix formation kinetics of fully atomistic peptide models in explicit solvent are described quantitatively by a diffusive search within the coil state with barrierless transitions into the helical state. Conformational diffusion leads to nonexponential kinetics and jump-width dependences in temperature jump experiments. (c) 2000 The American Physical Society

Conformational Diffusion and Helix Formation Kinetics

Energy Technology Data Exchange (ETDEWEB)

Hummer, Gerhard [Laboratory of Chemical Physics, Building 5, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520 (United States); Garcia, Angel E. [Theoretical Biology and Biophysics Group T-10, MS K710, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Garde, Shekhar [Department of Chemical Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180 (United States)

2000-09-18

The time, temperature, and sequence dependences of helix formation kinetics of fully atomistic peptide models in explicit solvent are described quantitatively by a diffusive search within the coil state with barrierless transitions into the helical state. Conformational diffusion leads to nonexponential kinetics and jump-width dependences in temperature jump experiments. (c) 2000 The American Physical Society.

Disruption of the LOV-Jalpha helix interaction activates phototropin kinase activity.

Science.gov (United States)

Harper, Shannon M; Christie, John M; Gardner, Kevin H

2004-12-28

Light plays a crucial role in activating phototropins, a class of plant photoreceptors that are sensitive to blue and UV-A wavelengths. Previous studies indicated that phototropin uses a bound flavin mononucleotide (FMN) within its light-oxygen-voltage (LOV) domain to generate a protein-flavin covalent bond under illumination. In the C-terminal LOV2 domain of Avena sativa phototropin 1, formation of this bond triggers a conformational change that results in unfolding of a helix external to this domain called Jalpha [Harper, S. M., et al. (2003) Science 301, 1541-1545]. Though the structural effects of illumination were characterized, it was unknown how these changes are coupled to kinase activation. To examine this, we made a series of point mutations along the Jalpha helix to disrupt its interaction with the LOV domain in a manner analogous to light activation. Using NMR spectroscopy and limited proteolysis, we demonstrate that several of these mutations displace the Jalpha helix from the LOV domain independently of illumination. When placed into the full-length phototropin protein, these point mutations display constitutive kinase activation, without illumination of the sample. These results indicate that unfolding of the Jalpha helix is the critical event in regulation of kinase signaling for the phototropin proteins.

Which Specialized Metabolites Does the Native Subantarctic Gastropod Notodiscus hookeri Extract from the Consumption of the Lichens Usnea taylorii and Pseudocyphellaria crocata?

Science.gov (United States)

Gadea, Alice; Le Pogam, Pierre; Biver, Grichka; Boustie, Joël; Le Lamer, Anne-Cécile; Le Dévéhat, Françoise; Charrier, Maryvonne

2017-03-08

Notodiscus hookeri is the only representative of terrestrial gastropods on Possession Island and exclusively feeds on lichens. The known toxicity of various lichen metabolites to plant-eating invertebrates led us to propose that N. hookeri evolved means to protect itself from their adverse effects. To validate this assumption, the current study focused on the consumption of two lichen species: Usnea taylorii and Pseudocyphellaria crocata . A controlled feeding experiment was designed to understand how the snail copes with the unpalatable and/or toxic compounds produced by these lichen species. The occurrence of two snail ecophenotypes, represented by a mineral shell and an organic shell, led to address the question of a metabolic response specific to the phenotype. Snails were fed for two months with one of these lichens and the chemical profiles of biological samples of N. hookeri (i.e., crop, digestive gland, intestine, and feces) were established by HPLC-DAD-MS and compared to that of the lichens. N. hookeri appears as a generalist lichen feeder able to consume toxic metabolite-containing lichens, independently of the ecophenotype. The digestive gland did not sequester lichen metabolites. The snail metabolism might be based on four non-exclusive processes according to the concerned metabolites (avoidance, passive transport, hydrolysis, and excretion).

Which Specialized Metabolites Does the Native Subantarctic Gastropod Notodiscus hookeri Extract from the Consumption of the Lichens Usnea taylorii and Pseudocyphellaria crocata?

Directory of Open Access Journals (Sweden)

Alice Gadea

2017-03-01

Full Text Available Notodiscus hookeri is the only representative of terrestrial gastropods on Possession Island and exclusively feeds on lichens. The known toxicity of various lichen metabolites to plant-eating invertebrates led us to propose that N. hookeri evolved means to protect itself from their adverse effects. To validate this assumption, the current study focused on the consumption of two lichen species: Usnea taylorii and Pseudocyphellaria crocata. A controlled feeding experiment was designed to understand how the snail copes with the unpalatable and/or toxic compounds produced by these lichen species. The occurrence of two snail ecophenotypes, represented by a mineral shell and an organic shell, led to address the question of a metabolic response specific to the phenotype. Snails were fed for two months with one of these lichens and the chemical profiles of biological samples of N. hookeri (i.e., crop, digestive gland, intestine, and feces were established by HPLC-DAD-MS and compared to that of the lichens. N. hookeri appears as a generalist lichen feeder able to consume toxic metabolite-containing lichens, independently of the ecophenotype. The digestive gland did not sequester lichen metabolites. The snail metabolism might be based on four non-exclusive processes according to the concerned metabolites (avoidance, passive transport, hydrolysis, and excretion.

13-Helix folding of a β/γ-peptide manifold designed from a "minimal-constraint" blueprint.

Science.gov (United States)

Grison, Claire M; Robin, Sylvie; Aitken, David J

2016-06-14

A bottom-up design rationale was adopted to devise β/γ-peptide foldamer manifolds which would adopt preferred 13-helix conformations, relying on minimal steric imposition brought by the constituent amino acid residues. In this way, a well-defined 13-helix conformer was revealed for short oligomers of trans-2-aminocyclobutanecarboxylic acid and γ(4)-amino acids in alternation, which gave good topological superposition upon an α-helix motif.

Tetrodotoxin and paralytic shellfish poisons in gastropod species from Vietnam analyzed by high-performance liquid chromatography and liquid chromatography–tandem mass spectrometry

Directory of Open Access Journals (Sweden)

Hsiao-Chin Jen

2014-06-01

Full Text Available Among marine toxins, tetrodotoxin (TTX and paralytic shellfish poisons (PSPs are known as notorious neurotoxins that induce serious food poisoning incidents in the Southeast Asia region. The aim of this study was to investigate whether TTX and PSP toxins are important issues of seafood safety. Paralytic toxicity was observed in mice exposed to 34 specimens from five species of gastropods using a PSP bioassay. Five species of gastropods, Natica vitellus, Natica tumidus, Oliva hirasei, Oliva lignaria, and Oliva annulata, were collected from the coastal seawaters in Nha Trang City, Vietnam, between August 2007 and October 2007. The average lethal potency of gastropod specimens was 90 ± 40 (mean ± standard deviation mouse units (MU for N. vitellus, 64 ± 19 MU for N. tumidus, 42 ± 28 MU for O. hirasei, 51 ± 17 MU for O. lignaria, and 39 ± 18 MU for O. annulata. All toxic extracts from the sample species were clarified using a C18 Sep-Pak solid-phase extraction column and a microcentrifuge filter prior to analysis. High-performance liquid chromatography coupled with fluorescence detection indicated that the toxins of the olive shell (O. hirasei, O. lignaria, and O. annulata were mainly composed of saxitoxin (STX (73–82%, gonyautoxin (GTX 2, 3 (12–22%, and minor levels of TTX (5–6%. The toxins of N. vitellus and N. tumidus were mainly composed of STX (76–81% and GTX 1, 4 (19–24%. Furthermore, liquid chromatography–tandem mass spectrometry analysis was used to verify the identity of the PSPs and TTX. Our evidence shows that these gastropods have novel toxin profiles.

Reovirus FAST Proteins Drive Pore Formation and Syncytiogenesis Using a Novel Helix-Loop-Helix Fusion-Inducing Lipid Packing Sensor.

Directory of Open Access Journals (Sweden)

Jolene Read

2015-06-01

Full Text Available Pore formation is the most energy-demanding step during virus-induced membrane fusion, where high curvature of the fusion pore rim increases the spacing between lipid headgroups, exposing the hydrophobic interior of the membrane to water. How protein fusogens breach this thermodynamic barrier to pore formation is unclear. We identified a novel fusion-inducing lipid packing sensor (FLiPS in the cytosolic endodomain of the baboon reovirus p15 fusion-associated small transmembrane (FAST protein that is essential for pore formation during cell-cell fusion and syncytiogenesis. NMR spectroscopy and mutational studies indicate the dependence of this FLiPS on a hydrophobic helix-loop-helix structure. Biochemical and biophysical assays reveal the p15 FLiPS preferentially partitions into membranes with high positive curvature, and this partitioning is impeded by bis-ANS, a small molecule that inserts into hydrophobic defects in membranes. Most notably, the p15 FLiPS can be functionally replaced by heterologous amphipathic lipid packing sensors (ALPS but not by other membrane-interactive amphipathic helices. Furthermore, a previously unrecognized amphipathic helix in the cytosolic domain of the reptilian reovirus p14 FAST protein can functionally replace the p15 FLiPS, and is itself replaceable by a heterologous ALPS motif. Anchored near the cytoplasmic leaflet by the FAST protein transmembrane domain, the FLiPS is perfectly positioned to insert into hydrophobic defects that begin to appear in the highly curved rim of nascent fusion pores, thereby lowering the energy barrier to stable pore formation.

[Biology and ecology of the terrestrial hermit crab coenobita scaevola forskål of the Red Sea].

Science.gov (United States)

Niggemann, Renate

1968-06-01

The terrestrial hermit crab Coenobita scaevola is very common on the coast of the Red Sea. The species depends on the sea for its source of food (wrack-fauna), source of drinking-water and water for moistening gills and abdomen. Only in the supra-litoral zone they find gastropod shells to protect their abdomen against insolation, desiccation and mechanical damage. Coenobita scaevola stays in one place for a long time if good living conditions are available. The time of activity of the juveniles differs from one place to another. Some are diurnal, others are nocturnal. There is no evident relation to the ecological factors. Most of the adults are nocturnal. No Coenobita could be collected in Barber traps. The avoidance of such traps by arthropodes has never been observed before. Coenobita scaevola can live for quite a long time under water of sufficient temperature and salinity. The osmotic regulation of the land-hermit crab differs from that of other shore animals. Coenobita can tolerate a wide range of blood concentrations (25-70‰). It controls the concentration of its blood by selecting water of the appropriate salinity.The static problems of Coenobita are solved by regular movement of the legs and special articulation of the legs.As Coenobita scaevola is a phylogenetically young land animal it carries many inhabitants of marine and terrestrial origin.

Change of hemoagglutinin and hemolysin titers in hemolymph of gastropod molluscs in response to immunization with sheep erythrocytes

NARCIS (Netherlands)

Baskakov, AV; Polevshchikov, AV; Harazova, AD; Krasnodembskii, EG

2000-01-01

This work deals with analysis of changes of the levels of hemoagglutinins (HA) and hemolysins (HL) in hemolymph of three gastropod species, Planorbius corneus, Lymnea stagnalis, and Achatina fulica, in response to immunization with sheep erythrocytes (ShE). The levels of HA and HL were determined

Ecosystem engineering potential of the gastropod Terebralia palustris (Linnaeus, 1767) in mangrove wastewater wetlands - A controlled mesocosm experiment

Energy Technology Data Exchange (ETDEWEB)

Penha-Lopes, Gil, E-mail: gil.penha-lopes@biology-research.co [Centro de Oceanografia - Laboratorio Maritimo da Guia, Departamento de Biologia Animal, Faculdade de Ciencias da Universidade de Lisboa, Avenida Na, Senhora do Cabo 939, 2750-374 Cascais (Portugal); Department of Analytical and Environmental Chemistry, Vrije Universiteit Brussels, Brussels (Belgium); Bartolini, Fabrizio [Dipartimento di Biologia Evoluzionistica, Universita degli Studi di Firenze, via Romana 17, I-50125 Firenze (Italy); Limbu, Samwel [University of Dar es Salaam, Department of Aquatic Sciences and Fisheries, P.O. Box 35064, Dar es Salaam (Tanzania, United Republic of); Cannicci, Stefano [Dipartimento di Biologia Evoluzionistica, Universita degli Studi di Firenze, via Romana 17, I-50125 Firenze (Italy); Mgaya, Yunus [University of Dar es Salaam, Department of Aquatic Sciences and Fisheries, P.O. Box 35064, Dar es Salaam (Tanzania, United Republic of); Kristensen, Erik [Institute of Biology, University of Southern Denmark, DK-5230 Odense M (Denmark); Paula, Jose [Centro de Oceanografia - Laboratorio Maritimo da Guia, Departamento de Biologia Animal, Faculdade de Ciencias da Universidade de Lisboa, Avenida Na, Senhora do Cabo 939, 2750-374 Cascais (Portugal)

2010-01-15

The effect of different sewage concentrations (0, 20, 60 and 100%), vegetation (Bare, Avicennia marina or Rhizophora mucronata) and immersion periods (immersion/emersion period of 12/12 h or 3/3 days just for 100%) conditions were studied for 6 months on survival and growth rates of Terebralia palustris (Linnaeus, 1767). Gastropods' activity and ecosystem engineering preformed at bare and A. marina planted cells and 3 sewage conditions (0, 20 and 60%) were determined. Survival rates were higher than 70% in all treatments. Growth rate decreased significantly with increasing sewage concentrations (mainly at unplanted conditions) and longer immersion periods. A complete shift (from immersion to emersion periods) and a significant decrease in mobility and consequently its engineer potential, due to sewage contamination, lead to a 3-4 fold decrease in the amount of sediment disturbed. Sewage contamination, primary producers' abundance and environmental conditions may have influenced the gastropods survival, growth and its ecosystem engineering potential. - Terebralia palustris high ecosystem engineering potential in constructed mangrove wetlands.

[Taphonomy of the gastropod cf. Donaldina robusta (Heterobranchia: Streptacididae) from the Middle Pennsylvanian, La Joya Formation, Sonora, Mexico].

Science.gov (United States)

Gómez E, Catalina; Buitrón S, Blanca; Vachard, Daniel

2010-03-01

Gastropods are an important component in most of the fossil record; however, investigations have focused mainly on the characterization of the tafofacies and signatures in determined environments. We present qualitative and quantitative taphonomic data for the gastropod cf. Donaldina robusta assemblages from the La Joya Formation of the Sierra Agua Verde, Sonora State, (NW) Mexico. We analyzed 176 shells. Good preservation received ahigh taphonomic grade (A) and poor preservation a D. The shells were complete in 72% of cases (taphonomic grade B). Less than 10% are corroded or are parallel to the layer (grade A). This rock is petrographycally classified as wackestone, sedimentologically it is characterized by middle sorting (grade B) and low grading (grade A). The fossiliferous assemblage grades as A and B. Biostratinomic features of the skeletal assemblage are characteristic of sedimentologic concentrations of autochthonous-parautochthonous elements at the accumulation site. There was minimal reworking and transport in an environment of low energy, locally produced during a short period of accumulation.

Geometry of the toroidal N-helix: optimal-packing and zero-twist

DEFF Research Database (Denmark)

Olsen, Kasper; Bohr, Jakob

2012-01-01

Two important geometrical properties of N-helix structures are influenced by bending. One is maximizing the volume fraction, which is called optimal-packing, and the other is having a vanishing strain-twist coupling, which is called zero-twist. Zero-twist helices rotate neither in one nor...... helix. General N-helices are discussed, as well as zero-twist helices for N > 1. The derived geometrical restrictions are gradually modified by changing the aspect ratio of the torus....

Neutral N-glycan patterns of the gastropods Limax maximus, Cepaea hortensis, Planorbarius corneus, Arianta arbustorum and Achatina fulica.

Science.gov (United States)

Gutternigg, Martin; Bürgmayr, Sabine; Pöltl, Gerald; Rudolf, Judith; Staudacher, Erika

2007-11-01

The N-glycosylation potentials of Limax maximus, Cepaea hortensis, Planorbarius corneus, Arianta arbustorum and Achatina fulica were analysed by investigation of the N-glycan structures of the skin and viscera glycoproteins by a combination of HPLC and mass-spectrometry methods. It is one of the first steps to enlarge the knowledge on the glycosylation abilities of gastropods, which may help to establish new cell culture systems, to uncover new means for pest control for some species, and to identify carbohydrate-epitopes which may be relevant for immune response. All snails analysed contained mainly oligomannosidic and small paucimannosidic structures, often terminated with 3-O-methylated mannoses. The truncated structures carried modifications by beta1-2-linked xylose to the beta-mannose residue, and/or an alpha-fucosylation, mainly alpha1,6-linked to the innermost N-acetylglucosaminyl residue of the core. Many of these structures were missing the terminal N-acetylglucosamine, which has been shown to be a prerequisite for processing to complex N-glycans in the Golgi. In some species (Planorbarius corneus and Achatina fulica) traces of large structures, terminated by 3-O-methylated galactoses and carrying xylose and/or fucose residues, were also detected. In Planorbarius viscera low amounts of terminal alpha1-2-fucosylation were determined. Combining these results, gastropods seem to be capable to produce all kinds of structures ranging from those typical in mammals through to structures similar to those found in plants, insects or nematodes. The detailed knowledge of this very complex glycosylation system of the gastropods will be a valuable tool to understand the principle rules of glycosylation in all organisms.

Progesterone modulation of transmembrane helix-helix interactions between the α-subunit of Na/K-ATPase and phospholipid N-methyltransferase in the oocyte plasma membrane

Directory of Open Access Journals (Sweden)

Askari Amir

2010-05-01

Full Text Available Abstract Background Progesterone binding to the surface of the amphibian oocyte initiates the meiotic divisions. Our previous studies with Rana pipiens oocytes indicate that progesterone binds to a plasma membrane site within the external loop between the M1 and M2 helices of the α-subunit of Na/K-ATPase, triggering a cascade of lipid second messengers and the release of the block at meiotic prophase. We have characterized this site, using a low affinity ouabain binding isoform of the α1-subunit. Results Preparations of isolated plasma membranes from Rana oocytes demonstrate that physiological levels of progesterone (or the non-metabolizable progestin R5020 successively activate phosphatidylethanolamine-N-methyltransferase (PE-NMT and sphingomyelin synthase within seconds. Inhibition of PE-NMT blocks the progesterone induction of meiosis in intact oocytes, whereas its initial product, phosphatidylmonomethylethanolamine (PME, can itself initiate meiosis in the presence of the inhibitor. Published X-ray crystallographic data on Na/K-ATPase, computer-generated 3D projections, heptad repeat analysis and hydrophobic cluster analysis of the transmembrane helices predict that hydrophobic residues L, V, V, I, F and Y of helix M2 of the α1-subunit interact with F, L, G, L, L and F, respectively, of helix M3 of PE-NMT. Conclusion We propose that progesterone binding to the first external loop of the α1-subunit facilitates specific helix-helix interactions between integral membrane proteins to up-regulate PE-NMT, and, that successive interactions between two or more integral plasma membrane proteins induce the signaling cascades which result in completion of the meiotic divisions.

Bioerosion of gastropod shells: with emphasis on effects of coralline algal cover and shell microstructure

Science.gov (United States)

Smyth, Miriam J.

1989-12-01

Organisms boring into fifty nine species of gastropod shells on reefs around Guam were the bryozoan Penetrantia clionoides; the acrothoracian barnacles Cryptophialus coronorphorus, Cryptophialus zulloi and Lithoglyptis mitis; the foraminifer Cymbaloporella tabellaeformis, the polydorid Polydora sp. and seven species of clionid sponge. Evidence that crustose coralline algae interfere with settlement of larvae of acrothoracian barnacles, clionid sponges, and boring polychaetes came from two sources: (1) low intensity of boring in limpet shells, a potentially penetrable substrate that remains largely free of borings by virtue of becoming fully covered with coralline algae at a young age and (2) the extremely low levels of boring in the algal ridge, a massive area of carbonate almost entirely covered by a layer of living crustose corallines. There was a strong negative correlation between microstructural hardness and infestation by acrothoracian barnacles and no correlation in the case of the other borers. It is suggested that this points to a mechanical rather than a chemical method of boring by the barnacles. The periostracum, a layer of organic material reputedly a natural inhibitor of boring organisms, was bored by acrothoracican barnacles and by the bryozoan. The intensity of acrothoracican borings is shown to have no correlation with the length of the gastropod shell.

Genome-wide identification and analysis of basic helix-loop-helix domains in dog, Canis lupus familiaris.

Science.gov (United States)

Wang, Xu-Hua; Wang, Yong; Liu, A-Ke; Liu, Xiao-Ting; Zhou, Yang; Yao, Qin; Chen, Ke-Ping

2015-04-01

The basic helix-loop-helix (bHLH) domain is a highly conserved amino acid motif that defines a group of DNA-binding transcription factors. bHLH proteins play essential regulatory roles in a variety of biological processes in animal, plant, and fungus. The domestic dog, Canis lupus familiaris, is a good model organism for genetic, physiological, and behavioral studies. In this study, we identified 115 putative bHLH genes in the dog genome. Based on a phylogenetic analysis, 51, 26, 14, 4, 12, and 4 dog bHLH genes were assigned to six separate groups (A-F); four bHLH genes were categorized as ''orphans''. Within-group evolutionary relationships inferred from the phylogenetic analysis were consistent with positional conservation, other conserved domains flanking the bHLH motif, and highly conserved intron/exon patterns in other vertebrates. Our analytical results confirmed the GenBank annotations of 89 dog bHLH proteins and provided information that could be used to update the annotations of the remaining 26 dog bHLH proteins. These data will provide good references for further studies on the structures and regulatory functions of bHLH proteins in the growth and development of dogs, which may help in understanding the mechanisms that underlie the physical and behavioral differences between dogs and wolves.

DNA binding specificity of the basic-helix-loop-helix protein MASH-1.

Science.gov (United States)

Meierhan, D; el-Ariss, C; Neuenschwander, M; Sieber, M; Stackhouse, J F; Allemann, R K

1995-09-05

Despite the high degree of sequence similarity in their basic-helix-loop-helix (BHLH) domains, MASH-1 and MyoD are involved in different biological processes. In order to define possible differences between the DNA binding specificities of these two proteins, we investigated the DNA binding properties of MASH-1 by circular dichroism spectroscopy and by electrophoretic mobility shift assays (EMSA). Upon binding to DNA, the BHLH domain of MASH-1 underwent a conformational change from a mainly unfolded to a largely alpha-helical form, and surprisingly, this change was independent of the specific DNA sequence. The same conformational transition could be induced by the addition of 20% 2,2,2-trifluoroethanol. The apparent dissociation constants (KD) of the complexes of full-length MASH-1 with various oligonucleotides were determined from half-saturation points in EMSAs. MASH-1 bound as a dimer to DNA sequences containing an E-box with high affinity KD = 1.4-4.1 x 10(-14) M2). However, the specificity of DNA binding was low. The dissociation constant for the complex between MASH-1 and the highest affinity E-box sequence (KD = 1.4 x 10(-14) M2) was only a factor of 10 smaller than for completely unrelated DNA sequences (KD = approximately 1 x 10(-13) M2). The DNA binding specificity of MASH-1 was not significantly increased by the formation of an heterodimer with the ubiquitous E12 protein. MASH-1 and MyoD displayed similar binding site preferences, suggesting that their different target gene specificities cannot be explained solely by differential DNA binding. An explanation for these findings is provided on the basis of the known crystal structure of the BHLH domain of MyoD.

Tah1 helix-swap dimerization prevents mixed Hsp90 co-chaperone complexes

International Nuclear Information System (INIS)

Morgan, Rhodri M. L.; Pal, Mohinder; Roe, S. Mark; Pearl, Laurence H.; Prodromou, Chrisostomos

2015-01-01

A helix swap involving the fifth helix between two adjacently bound Tah1 molecules restores the normal binding environment of the conserved MEEVD peptide of Hsp90. Dimerization also explains how other monomeric TPR-domain proteins are excluded from forming inappropriate mixed co-chaperone complexes with Hsp90 and Tah1. Specific co-chaperone adaptors facilitate the recruitment of client proteins to the Hsp90 system. Tah1 binds the C-terminal conserved MEEVD motif of Hsp90, thus linking an eclectic set of client proteins to the R2TP complex for their assembly and regulation by Hsp90. Rather than the normal complement of seven α-helices seen in other tetratricopeptide repeat (TPR) domains, Tah1 unusually consists of the first five only. Consequently, the methionine of the MEEVD peptide remains exposed to solvent when bound by Tah1. In solution Tah1 appears to be predominantly monomeric, and recent structures have failed to explain how Tah1 appears to prevent the formation of mixed TPR domain-containing complexes such as Cpr6–(Hsp90) 2 –Tah1. To understand this further, the crystal structure of Tah1 in complex with the MEEVD peptide of Hsp90 was determined, which shows a helix swap involving the fifth α-helix between two adjacently bound Tah1 molecules. Dimerization of Tah1 restores the normal binding environment of the bound Hsp90 methionine residue by reconstituting a TPR binding site similar to that in seven-helix-containing TPR domain proteins. Dimerization also explains how other monomeric TPR-domain proteins are excluded from forming inappropriate mixed co-chaperone complexes

Tah1 helix-swap dimerization prevents mixed Hsp90 co-chaperone complexes

Energy Technology Data Exchange (ETDEWEB)

Morgan, Rhodri M. L.; Pal, Mohinder; Roe, S. Mark; Pearl, Laurence H., E-mail: laurence.pearl@sussex.ac.uk; Prodromou, Chrisostomos, E-mail: laurence.pearl@sussex.ac.uk [University of Sussex, Falmer, Brighton BN1 9RQ (United Kingdom)

2015-05-01

A helix swap involving the fifth helix between two adjacently bound Tah1 molecules restores the normal binding environment of the conserved MEEVD peptide of Hsp90. Dimerization also explains how other monomeric TPR-domain proteins are excluded from forming inappropriate mixed co-chaperone complexes with Hsp90 and Tah1. Specific co-chaperone adaptors facilitate the recruitment of client proteins to the Hsp90 system. Tah1 binds the C-terminal conserved MEEVD motif of Hsp90, thus linking an eclectic set of client proteins to the R2TP complex for their assembly and regulation by Hsp90. Rather than the normal complement of seven α-helices seen in other tetratricopeptide repeat (TPR) domains, Tah1 unusually consists of the first five only. Consequently, the methionine of the MEEVD peptide remains exposed to solvent when bound by Tah1. In solution Tah1 appears to be predominantly monomeric, and recent structures have failed to explain how Tah1 appears to prevent the formation of mixed TPR domain-containing complexes such as Cpr6–(Hsp90){sub 2}–Tah1. To understand this further, the crystal structure of Tah1 in complex with the MEEVD peptide of Hsp90 was determined, which shows a helix swap involving the fifth α-helix between two adjacently bound Tah1 molecules. Dimerization of Tah1 restores the normal binding environment of the bound Hsp90 methionine residue by reconstituting a TPR binding site similar to that in seven-helix-containing TPR domain proteins. Dimerization also explains how other monomeric TPR-domain proteins are excluded from forming inappropriate mixed co-chaperone complexes.

Fluorophores, environments, and quantification techniques in the analysis of transmembrane helix interaction using FRET.

Science.gov (United States)

Khadria, Ambalika S; Senes, Alessandro

2015-07-01

Förster resonance energy transfer (FRET) has been widely used as a spectroscopic tool in vitro to study the interactions between transmembrane (TM) helices in detergent and lipid environments. This technique has been instrumental to many studies that have greatly contributed to quantitative understanding of the physical principles that govern helix-helix interactions in the membrane. These studies have also improved our understanding of the biological role of oligomerization in membrane proteins. In this review, we focus on the combinations of fluorophores used, the membrane mimetic environments, and measurement techniques that have been applied to study model systems as well as biological oligomeric complexes in vitro. We highlight the different formalisms used to calculate FRET efficiency and the challenges associated with accurate quantification. The goal is to provide the reader with a comparative summary of the relevant literature for planning and designing FRET experiments aimed at measuring TM helix-helix associations. © 2015 Wiley Periodicals, Inc.

Interactions between an alpha-helix and a beta-sheet. Energetics of alpha/beta packing in proteins.

Science.gov (United States)

Chou, K C; Némethy, G; Rumsey, S; Tuttle, R W; Scheraga, H A

1985-12-05

Conformational energy computations have been carried out to determine the favorable ways of packing a right-handed alpha-helix on a right-twisted antiparallel or parallel beta-sheet. Co-ordinate transformations have been developed to relate the position and orientation of the alpha-helix to the beta-sheet. The packing was investigated for a CH3CO-(L-Ala)16-NHCH3 alpha-helix interacting with five-stranded beta-sheets composed of CH3CO-(L-Val)6-NHCH3 chains. All internal and external variables for both the alpha-helix and the beta-sheet were allowed to change during energy minimization. Four distinct classes of low-energy packing arrangements were found for the alpha-helix interacting with both the parallel and the anti-parallel beta-sheet. The classes differ in the orientation of the axis of the alpha-helix relative to the direction of the strands of the right-twisted beta-sheet. In the class with the most favorable arrangement, the alpha-helix is oriented along the strands of the beta-sheet, as a result of attractive non-bonded side-chain-side-chain interactions along the entire length of the alpha-helix. A class with nearly perpendicular orientation of the helix axis to the strands is also of low energy, because it allows similarly extensive attractive interactions. In the other two classes, the helix is oriented diagonally relative to the strands of the beta-sheet. In one of them, it interacts with the convex surface near the middle of the saddle-shaped twisted beta-sheet. In the other, it is oriented along the concave diagonal of the beta-sheet and, therefore, it interacts only with the corner regions of the sheet, so that this packing is energetically less favorable. The packing arrangements involving an antiparallel and a parallel beta-sheet are generally similar, although the antiparallel beta-sheet has been found to be more flexible. The major features of 163 observed alpha/beta packing arrangements in 37 proteins are accounted for in terms of the computed

The Alpha-Helix Concept: Innovative utilization of the Space Station Program. A report to the National Aeronautical and Space Administration requesting establishment of a Sensory Physiology Laboratory on the Space Station

Science.gov (United States)

Bandurski, R. S.; Singh, N.

1983-01-01

A major laboratory dedicated to biological-medical research is proposed for the Space Platform. The laboratory would focus on sensor physiology and biochemistry since sensory physiology represents the first impact of the new space environment on living organisms. Microgravity and the high radiation environment of space would be used to help solve the problems of prolonged sojourns in space but, more importantly, to help solve terrestrial problems of human health and agricultural productivity. The emphasis would be on experimental use of microorganisms and small plants and small animals to minimize the space and time required to use the Space Platform for maximum human betterment. The Alpha Helix Concept, that is, the use of the Space Platform to bring experimental biomedicine to a new and extreme frontier is introduced so as to better understand the worldly environment. Staffing and instrumenting the Space Platform biomedical laboratory in a manner patterned after successful terrestrial sensory physiology laboratories is also proposed.

Gate-controlled switching between persistent and inverse persistent spin helix states

International Nuclear Information System (INIS)

Yoshizumi, K.; Sasaki, A.; Kohda, M.; Nitta, J.

2016-01-01

We demonstrate gate-controlled switching between persistent spin helix (PSH) state and inverse PSH state, which are detected by quantum interference effect on magneto-conductance. These special symmetric spin states showing weak localization effect give rise to a long spin coherence when the strength of Rashba spin-orbit interaction (SOI) is close to that of Dresselhaus SOI. Furthermore, in the middle of two persistent spin helix states, where the Rashba SOI can be negligible, the bulk Dresselhaus SOI parameter in a modulation doped InGaAs/InAlAs quantum well is determined.

Gate-controlled switching between persistent and inverse persistent spin helix states

Energy Technology Data Exchange (ETDEWEB)

Yoshizumi, K.; Sasaki, A.; Kohda, M.; Nitta, J. [Department of Materials Science, Tohoku University, Sendai 980-8579 (Japan)

2016-03-28

We demonstrate gate-controlled switching between persistent spin helix (PSH) state and inverse PSH state, which are detected by quantum interference effect on magneto-conductance. These special symmetric spin states showing weak localization effect give rise to a long spin coherence when the strength of Rashba spin-orbit interaction (SOI) is close to that of Dresselhaus SOI. Furthermore, in the middle of two persistent spin helix states, where the Rashba SOI can be negligible, the bulk Dresselhaus SOI parameter in a modulation doped InGaAs/InAlAs quantum well is determined.

The Quadruple Helix Model Enhancing Innovative Performance Of Indonesian Creative Industry

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Sri Wahyu Lelly Hana Setyanti

2017-11-01

Full Text Available The creative industry in Indonesia has contributed positively to the national economic growth. Creative industry grows from the creativity and innovation performance of the business actors. The challenge of creative industry is how to completely understand the creative and innovative processes in business management. Therefore it requires an approach that combines the synergy between academicians entrepreneurs government and society in a quadruple helix model. The objective of this research is to develop a creativity model through a quadruple helix model in improving innovation performance of the creative industry.

Design and synthesis of DNA four-helix bundles

Energy Technology Data Exchange (ETDEWEB)

Rangnekar, Abhijit; Gothelf, Kurt V [Department of Chemistry, Centre for DNA Nanotechnology (CDNA) and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, DK-8000 Aarhus C (Denmark); LaBean, Thomas H, E-mail: kvg@chem.au.dk, E-mail: thl@cs.duke.edu [Department of Chemistry, Duke University, Durham, NC 27708 (United States)

2011-06-10

The field of DNA nanotechnology has evolved significantly in the past decade. Researchers have succeeded in synthesizing tile-based structures and using them to form periodic lattices in one, two and three dimensions. Origami-based structures have also been used to create nanoscale structures in two and three dimensions. Design and construction of DNA bundles with fixed circumference has added a new dimension to the field. Here we report the design and synthesis of a DNA four-helix bundle. It was found to be extremely rigid and stable. When several such bundles were assembled using appropriate sticky-ends, they formed micrometre-long filaments. However, when creation of two-dimensional sheet-like arrays of the four-helix bundles was attempted, nanoscale rings were observed instead. The exact reason behind the nanoring formation is yet to be ascertained, but it provides an exciting prospect for making programmable circular nanostructures using DNA.

Design and synthesis of DNA four-helix bundles

International Nuclear Information System (INIS)

Rangnekar, Abhijit; Gothelf, Kurt V; LaBean, Thomas H

2011-01-01

The field of DNA nanotechnology has evolved significantly in the past decade. Researchers have succeeded in synthesizing tile-based structures and using them to form periodic lattices in one, two and three dimensions. Origami-based structures have also been used to create nanoscale structures in two and three dimensions. Design and construction of DNA bundles with fixed circumference has added a new dimension to the field. Here we report the design and synthesis of a DNA four-helix bundle. It was found to be extremely rigid and stable. When several such bundles were assembled using appropriate sticky-ends, they formed micrometre-long filaments. However, when creation of two-dimensional sheet-like arrays of the four-helix bundles was attempted, nanoscale rings were observed instead. The exact reason behind the nanoring formation is yet to be ascertained, but it provides an exciting prospect for making programmable circular nanostructures using DNA.

Design, synthesis, and evaluation of an alpha-helix mimetic library targeting protein-protein interactions.

Science.gov (United States)

Shaginian, Alex; Whitby, Landon R; Hong, Sukwon; Hwang, Inkyu; Farooqi, Bilal; Searcey, Mark; Chen, Jiandong; Vogt, Peter K; Boger, Dale L

2009-04-22

The design and solution-phase synthesis of an alpha-helix mimetic library as an integral component of a small-molecule library targeting protein-protein interactions are described. The iterative design, synthesis, and evaluation of the candidate alpha-helix mimetic was initiated from a precedented triaryl template and refined by screening the designs for inhibition of MDM2/p53 binding. Upon identifying a chemically and biologically satisfactory design and consistent with the screening capabilities of academic collaborators, the corresponding complete library was assembled as 400 mixtures of 20 compounds (20 x 20 x 20-mix), where the added subunits are designed to mimic all possible permutations of the naturally occurring i, i + 4, i + 7 amino acid side chains of an alpha-helix. The library (8000 compounds) was prepared using a solution-phase synthetic protocol enlisting acid/base liquid-liquid extractions for purification on a scale that insures its long-term availability for screening campaigns. Screening of the library for inhibition of MDM2/p53 binding not only identified the lead alpha-helix mimetic upon which the library was based, but also suggests that a digestion of the initial screening results that accompany the use of such a comprehensive library can provide insights into the nature of the interaction (e.g., an alpha-helix mediated protein-protein interaction) and define the key residues and their characteristics responsible for recognition.

pH-jump induced α-helix folding of poly-L-glutamic acid

International Nuclear Information System (INIS)

Donten, Mateusz L.; Hamm, Peter

2013-01-01

Highlights: ► pH-jump as truly biomimetic tool to initiate non-equilibrium dynamics of biomolecules. ► Design criteria to widen the applicability of pH-jumps are developed. ► Folding of poly-L-Glu in dependence of starting pH, pH jump size and helix length. ► Length dependence provides strong evidence for a nucleation–propagation scenario. - Abstract: pH jumps are a truly biomimetic technique to initiate non-equilibrium dynamics of biomolecules. In this work, the pH jump induced α-helix folding of poly-L-glutamic acid is investigated upon proton release from o-nitrobenzaldehyde. The aim of this work is twofold: On the one hand, design criteria of pH jump experiments are discussed, on the other hand, the folding mechanism of poly-L-glutamic acid is clarified by probing the IR response of the amide I band. Its folding kinetics is studied in dependence of the starting pD, the size of the pD jump and the length of the helix. While no dependence on the first two parameters could be detected, the folding time varies from 0.6 μs to 1.8 μs for helix lengths of 20 residue to 440 residue, respectively. It converges to a long-length limit at about 50 residue, a result which is attributed to a nucleation–propagation mechanism

Positive selection and propeptide repeats promote rapid interspecific divergence of a gastropod sperm protein.

Science.gov (United States)

Hellberg, M E; Moy, G W; Vacquier, V D

2000-03-01

Male-specific proteins have increasingly been reported as targets of positive selection and are of special interest because of the role they may play in the evolution of reproductive isolation. We report the rapid interspecific divergence of cDNA encoding a major acrosomal protein of unknown function (TMAP) of sperm from five species of teguline gastropods. A mitochondrial DNA clock (calibrated by congeneric species divided by the Isthmus of Panama) estimates that these five species diverged 2-10 MYA. Inferred amino acid sequences reveal a propeptide that has diverged rapidly between species. The mature protein has diverged faster still due to high nonsynonymous substitution rates (> 25 nonsynonymous substitutions per site per 10(9) years). cDNA encoding the mature protein (89-100 residues) shows evidence of positive selection (Dn/Ds > 1) for 4 of 10 pairwise species comparisons. cDNA and predicted secondary-structure comparisons suggest that TMAP is neither orthologous nor paralogous to abalone lysin, and thus marks a second, phylogenetically independent, protein subject to strong positive selection in free-spawning marine gastropods. In addition, an internal repeat in one species (Tegula aureotincta) produces a duplicated cleavage site which results in two alternatively processed mature proteins differing by nine amino acid residues. Such alternative processing may provide a mechanism for introducing novel amino acid sequence variation at the amino-termini of proteins. Highly divergent TMAP N-termini from two other tegulines (Tegula regina and Norrisia norrisii) may have originated by such a mechanism.

Traces (ichnospecies Oichnus paraboloides of predatory gastropods on bivalve shells from the Seogwipo Formation, Jejudo, Korea

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Dal-Yong Kong

2015-12-01

Full Text Available Circular to subcircular drill holes were identified on the bivalve shells collected from the Seogwipo Formation, Jejudo, Korea. A great majority of the drill holes (>70% were found on the surfaces of a bivalve species Glycymeris rotunda. They are characterized by a beveled sharp edge and paraboloid in cross section with larger outer borehole diameter (OBD; mean 4.21 mm and smaller inner borehole diameter (mean 2.94 mm. Walls of the drill holes are generally smooth, and walls ornamented with etched relief-like structures were also recognized. A slightly raised central boss observed in an incomplete specimen may indicate a failure of predator’s attack. All drill holes collected are classified as a single ichnospecies Oichnus paraboloides Bromley, 1981. They are interpreted as boring traces produced by predatory gastropods, particularly naticid gastropods. Most O. paraboloides boreholes are observed in the central area of shell surfaces; a few boreholes lie marginally, which may reflect a borehole-site selectivity. No correlation between size of prey (shell height and size of predator (OBD is recognized. It is likely, however, that drilled shells of about 30 mm in height represent optimal prey size for naticid predators that lived in a benthic Seogwipo community.

Mechanism of death at high temperatures in Helix and Patella

Energy Technology Data Exchange (ETDEWEB)

Grainger, J N.R.

1975-10-01

In Patella vulgata and Helix aspersa which had been killed by exposure to high temperatures, the rates of oxygen consumption of gill, foot muscle and hepatopancreas are remarkably steady when measured at lower temperatures, although the absolute levels are in some cases different from normal animals. These tissues are thus substantially metabolically intact in heat dead individuals. In Helix there is a fall in blood sodium and a rise in blood potassium during heat death. In Patella there is a marked rise in blood Na/sup +/ and a consequent disturbance of the Na/sup +//K/sup +/ ratio. These ionic disturbances are thought to be a prime cause of heat death. The significance of the results is discussed.

Ab initio theory of helix <-> coil phase transition

DEFF Research Database (Denmark)

Yakubovich, Alexander V.; Solov'yov, Ilia; Solov'yov, Andrey V.

2008-01-01

In this paper, we suggest a theoretical method based on the statistical mechanics for treating the alpha-helix <-> random coil transition in alanine polypeptides. We consider this process as a first-order phase transition and develop a theory which is free of model parameters and is based solely ...

Correlated evolution between mode of larval development and habitat in muricid gastropods.

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Paula Pappalardo

Full Text Available Larval modes of development affect evolutionary processes and influence the distribution of marine invertebrates in the ocean. The decrease in pelagic development toward higher latitudes is one of the patterns of distribution most frequently discussed in marine organisms (Thorson's rule, which has been related to increased larval mortality associated with long pelagic durations in colder waters. However, the type of substrate occupied by adults has been suggested to influence the generality of the latitudinal patterns in larval development. To help understand how the environment affects the evolution of larval types we evaluated the association between larval development and habitat using gastropods of the Muricidae family as a model group. To achieve this goal, we collected information on latitudinal distribution, sea water temperature, larval development and type of substrate occupied by adults. We constructed a molecular phylogeny for 45 species of muricids to estimate the ancestral character states and to assess the relationship between traits using comparative methods in a Bayesian framework. Our results showed high probability for a common ancestor of the muricids with nonpelagic (and nonfeeding development, that lived in hard bottoms and cold temperatures. From this ancestor, a pelagic feeding larva evolved three times, and some species shifted to warmer temperatures or sand bottoms. The evolution of larval development was not independent of habitat; the most probable evolutionary route reconstructed in the analysis of correlated evolution showed that type of larval development may change in soft bottoms but in hard bottoms this change is highly unlikely. Lower sea water temperatures were associated with nonpelagic modes of development, supporting Thorson's rule. We show how environmental pressures can favor a particular mode of larval development or transitions between larval modes and discuss the reacquisition of feeding larva in

Correlated evolution between mode of larval development and habitat in muricid gastropods.

Science.gov (United States)

Pappalardo, Paula; Rodríguez-Serrano, Enrique; Fernández, Miriam

2014-01-01

Larval modes of development affect evolutionary processes and influence the distribution of marine invertebrates in the ocean. The decrease in pelagic development toward higher latitudes is one of the patterns of distribution most frequently discussed in marine organisms (Thorson's rule), which has been related to increased larval mortality associated with long pelagic durations in colder waters. However, the type of substrate occupied by adults has been suggested to influence the generality of the latitudinal patterns in larval development. To help understand how the environment affects the evolution of larval types we evaluated the association between larval development and habitat using gastropods of the Muricidae family as a model group. To achieve this goal, we collected information on latitudinal distribution, sea water temperature, larval development and type of substrate occupied by adults. We constructed a molecular phylogeny for 45 species of muricids to estimate the ancestral character states and to assess the relationship between traits using comparative methods in a Bayesian framework. Our results showed high probability for a common ancestor of the muricids with nonpelagic (and nonfeeding) development, that lived in hard bottoms and cold temperatures. From this ancestor, a pelagic feeding larva evolved three times, and some species shifted to warmer temperatures or sand bottoms. The evolution of larval development was not independent of habitat; the most probable evolutionary route reconstructed in the analysis of correlated evolution showed that type of larval development may change in soft bottoms but in hard bottoms this change is highly unlikely. Lower sea water temperatures were associated with nonpelagic modes of development, supporting Thorson's rule. We show how environmental pressures can favor a particular mode of larval development or transitions between larval modes and discuss the reacquisition of feeding larva in muricids gastropods.

De novo design, synthesis and characterisation of MP3, a new catalytic four-helix bundle hemeprotein.

Science.gov (United States)

Faiella, Marina; Maglio, Ornella; Nastri, Flavia; Lombardi, Angela; Lista, Liliana; Hagen, Wilfred R; Pavone, Vincenzo

2012-12-07

A new artificial metalloenzyme, MP3 (MiniPeroxidase 3), designed by combining the excellent structural properties of four-helix bundle protein scaffolds with the activity of natural peroxidases, was synthesised and characterised. This new hemeprotein model was developed by covalently linking the deuteroporphyrin to two peptide chains of different compositions to obtain an asymmetric helix-loop-helix/heme/helix-loop-helix sandwich arrangement, characterised by 1) a His residue on one chain that acts as an axial ligand to the iron ion; 2) a vacant distal site that is able to accommodate exogenous ligands or substrates; and 3) an Arg residue in the distal site that should assist in hydrogen peroxide activation to give an HRP-like catalytic process. MP3 was synthesised and characterised as its iron complex. CD measurements revealed the high helix-forming propensity of the peptide, confirming the appropriateness of the model procedure; UV/Vis, MCD and EPR experiments gave insights into the coordination geometry and the spin state of the metal. Kinetic experiments showed that Fe(III)-MP3 possesses peroxidase-like activity comparable to R38A-hHRP, highlighting the possibility of mimicking the functional features of natural enzymes. The synergistic application of de novo design methods, synthetic procedures, and spectroscopic characterisation, described herein, demonstrates a method by which to implement and optimise catalytic activity for an enzyme mimetic. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural plasticity of the N-terminal capping helix of the TPR domain of kinesin light chain.

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The Quyen Nguyen

Full Text Available Kinesin1 plays a major role in neuronal transport by recruiting many different cargos through its kinesin light chain (KLC. Various structurally unrelated cargos interact with the conserved tetratricopeptide repeat (TPR domain of KLC. The N-terminal capping helix of the TPR domain exhibits an atypical sequence and structural features that may contribute to the versatility of the TPR domain to bind different cargos. We determined crystal structures of the TPR domain of both KLC1 and KLC2 encompassing the N-terminal capping helix and show that this helix exhibits two distinct and defined orientations relative to the rest of the TPR domain. Such a difference in orientation gives rise, at the N-terminal part of the groove, to the formation of one hydrophobic pocket, as well as to electrostatic variations at the groove surface. We present a comprehensive structural analysis of available KLC1/2-TPR domain structures that highlights that ligand binding into the groove can be specific of one or the other N-terminal capping helix orientations. Further, structural analysis reveals that the N-terminal capping helix is always involved in crystal packing contacts, especially in a TPR1:TPR1' contact which highlights its propensity to be a protein-protein interaction site. Together, these results underline that the structural plasticity of the N-terminal capping helix might represent a structural determinant for TPR domain structural versatility in cargo binding.

Controlling chirality with helix inversion in cholesteric liquid crystals

NARCIS (Netherlands)

Katsonis, Nathalie Hélène; Lacaze, E.; Ferrarini, A.

2012-01-01

The helical organization of cholesteric liquid crystals is omnipresent in living matter. Achieving control over the structure of the cholesteric helix consequently holds great potential for developing stimuli-responsive materials matching the level of sophistication of biological systems. In

Zvyšky bratislavských lužných lesov – významné refúgium podunajskej malakofauny Remnants of alluvial woodland in a urbanised area – important refuge for Middle-Danubian land gastropods (Bratislava City, Slovakia

Directory of Open Access Journals (Sweden)

Juraj Čačaný

2012-10-01

Full Text Available The paper brings a review of a long-term malacological survey of fragmented urban alluvial woodland, an important refuge of Middle-Danubian terrestrial molluscan fauna. In the area of Bratislava agglomeration we surveyed two softwood and 26 hardwood alluvial forests. Altogether, 52 mollusc species have been recorded during the last 20 years (representing 79% of the total terrestrial mollusc fauna living in the Slovak section of the Danube floodplain. The most frequent species (more than 75% sites were Aegopinella nitens, Helix pomatia, Monachoides incarnatus (every three species at 27 sites, i.e. 96%, Cochlodina laminata (26 sites, 93%, Petasina unidentata (25 sites, Urticicola umbrosus (24 sites, Alinda biplicata (23 sites, and Clausilia pumila (21 sites. The main ecological groups were forest species in general (45%, mainly eurytopic and slightly hygrophilous, hygrophilous species in general (26%, hygrophilous and riparian, euryecious species (16%, semi-steppe (8% and open-country species (5%.

An unusual taphocoenosis of a sea urchin and a rectally inserted turriform gastropod from the lowermost Paleocene of Stevs klint, Denmark

DEFF Research Database (Denmark)

Milan, Jesper; Rasmussen, Bo Wilhelm; Vallon, Lothar H.

2015-01-01

A specimen of the common irregular echinoid Echinocorys sulcata (Goldfuss, 1826), recovered from the lowermost Paleocene Stevns Klint Formation, at Stevns Klint, Denmark, is of note in revealing a perfect external mold of the turriform gastropod Cerithiella fenestrata (Ravn, 1902) in the anal ope...

Equilibrium shift in solution: molecular shape recognition and precipitation of a synthetic double helix using helicene-grafted silica nanoparticles.

Science.gov (United States)

Miyagawa, Masamichi; Ichinose, Wataru; Yamaguchi, Masahiko

2014-01-27

Chiral silica nanoparticles (70 nm) grafted with (P)-helicene recognized the molecular shape of double helix and random coil (P)-ethynylhelicene oligomers in solution. A mixture of the (P)-nanoparticles and double helix precipitated much faster than a mixture of the (P)-nanoparticles and random coil, and the precipitate contained only the double helix. The mixture of the (P)-nanoparticles and (P)-ethynylhelicene pentamer reversibly dispersed in trifluoromethylbenzene upon heating at 70 °C and precipitated upon cooling at 25 °C. When a 10:90 equilibrium mixture of the double helix and random coil in solution was treated with the (P)-nanoparticles, the double helix was precipitated in 53% yield and was accompanied by equilibrium shift. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Classification and evolutionary analysis of the basic helix-loop-helix gene family in the green anole lizard, Anolis carolinensis.

Science.gov (United States)

Liu, Ake; Wang, Yong; Zhang, Debao; Wang, Xuhua; Song, Huifang; Dang, Chunwang; Yao, Qin; Chen, Keping

2013-08-01

Helix-loop-helix (bHLH) proteins play essential regulatory roles in a variety of biological processes. These highly conserved proteins form a large transcription factor superfamily, and are commonly identified in large numbers within animal, plant, and fungal genomes. The bHLH domain has been well studied in many animal species, but has not yet been characterized in non-avian reptiles. In this study, we identified 102 putative bHLH genes in the genome of the green anole lizard, Anolis carolinensis. Based on phylogenetic analysis, these genes were classified into 43 families, with 43, 24, 16, 3, 10, and 3 members assigned into groups A, B, C, D, E, and F, respectively, and 3 members categorized as "orphans". Within-group evolutionary relationships inferred from the phylogenetic analysis were consistent with highly conserved patterns observed for introns and additional domains. Results from phylogenetic analysis of the H/E(spl) family suggest that genome and tandem gene duplications have contributed to this family's expansion. Our classification and evolutionary analysis has provided insights into the evolutionary diversification of animal bHLH genes, and should aid future studies on bHLH protein regulation of key growth and developmental processes.

Phylogeny, Functional Annotation, and Protein Interaction Network Analyses of the Xenopus tropicalis Basic Helix-Loop-Helix Transcription Factors

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Wuyi Liu

2013-01-01

Full Text Available The previous survey identified 70 basic helix-loop-helix (bHLH proteins, but it was proved to be incomplete, and the functional information and regulatory networks of frog bHLH transcription factors were not fully known. Therefore, we conducted an updated genome-wide survey in the Xenopus tropicalis genome project databases and identified 105 bHLH sequences. Among the retrieved 105 sequences, phylogenetic analyses revealed that 103 bHLH proteins belonged to 43 families or subfamilies with 46, 26, 11, 3, 15, and 4 members in the corresponding supergroups. Next, gene ontology (GO enrichment analyses showed 65 significant GO annotations of biological processes and molecular functions and KEGG pathways counted in frequency. To explore the functional pathways, regulatory gene networks, and/or related gene groups coding for Xenopus tropicalis bHLH proteins, the identified bHLH genes were put into the databases KOBAS and STRING to get the signaling information of pathways and protein interaction networks according to available public databases and known protein interactions. From the genome annotation and pathway analysis using KOBAS, we identified 16 pathways in the Xenopus tropicalis genome. From the STRING interaction analysis, 68 hub proteins were identified, and many hub proteins created a tight network or a functional module within the protein families.

Observation of helix associations for insertion of a retinal molecule and distortions of helix structures in bacteriorhodopsin

Science.gov (United States)

Urano, Ryo; Okamoto, Yuko

2015-12-01

We applied a newly proposed prediction method for membrane protein structures to bacteriorhodopsin that has distorted transmembrane helices in the native structure. This method uses an implicit membrane model, which restricts sampling space during folding in a membrane region, and includes helix bending. Replica-exchange simulations were performed with seven transmembrane helices only without a retinal molecule. Obtained structures were classified into clusters of similar structures, which correspond to local-minimum free energy states. The two lowest free energy states corresponded to a native-like structure with the correct empty space for retinal and a structure with this empty space filled with a helix. Previous experiments of bacteriorhodopsin suggested that association of transmembrane helices enables them to make a room for insertion of a retinal. Our results are consistent with these results. Moreover, distortions of helices in the native-like structures were successfully reproduced. In the distortions, whereas the locations of kinks for all helices were similar to those of Protein Data Bank's data, the amount of bends was more similar for helices away from the retinal than for those close to the retinal in the native structure. This suggests a hypothesis that the amino-acid sequence specifies the location of kinks in transmembrane helices and that the amount of distortions depends on the interactions with the surrounding molecules such as neighboring helices, lipids, and retinal.

Study on the contamination by transuranides of Pulmonata gastropoda collected in Palomares (Spain)

International Nuclear Information System (INIS)

Aragon, A.; Espinosa, A.; Anton, M.P.

2006-01-01

A study on the contamination levels and distribution of plutonium in gastropods collected in Palomares (south-east Spain) has been performed. This region is partially contaminated with actinides following the nuclear accident occurred in 1966. The existence of plutonium in gastropods (Helix albicans and Theba pisana) along with their great gastronomic interest in the area reinforces the concern in studying the incorporation of these radioelements into a trophic level of the alimentary chain. In this work, plutonium concentration levels have been determined in the excrements, washing waters, flesh and shell of different types of gastropods collected in the Palomares most contaminated area. Plutonium analyses have been carried out following normalized procedures for the determination of this radionuclide. The results show the distribution of plutonium in washing and boiling water, excrements, soft tissues and shell of the snails. In addition, it has been estimated that the consumption of one kilogram of snails collected in the most contaminated area of Palomares could contribute up to 1/3 of the effective dose (due to ingestion) to the inhabitants of the area. (author)

New data on Paleocene-Eocene fauna (gastropods, ostracods, fishes) and palynoflora of the Boltysh impact structure (Ukraine) with reference to palaeobiogeography and palaeoecology

Czech Academy of Sciences Publication Activity Database

Dykan, N.; Kovalchuk, O.; Dykan, K.; Gurov, E.; Dašková, Jiřina; Přikryl, Tomáš

2018-01-01

Roč. 287, č. 2 (2018), s. 213-239 ISSN 0077-7749 Institutional support: RVO:67985831 Keywords : pollen * gastropods * ostracods * fishes * Boltysh * Paleogene * Eastern Eurpúe Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.777, year: 2016

Self-assembled RNA-triple-helix hydrogel scaffold for microRNA modulation in the tumour microenvironment

Science.gov (United States)

Conde, João; Oliva, Nuria; Atilano, Mariana; Song, Hyun Seok; Artzi, Natalie

2016-03-01

The therapeutic potential of miRNA (miR) in cancer is limited by the lack of efficient delivery vehicles. Here, we show that a self-assembled dual-colour RNA-triple-helix structure comprising two miRNAs--a miR mimic (tumour suppressor miRNA) and an antagomiR (oncomiR inhibitor)--provides outstanding capability to synergistically abrogate tumours. Conjugation of RNA triple helices to dendrimers allows the formation of stable triplex nanoparticles, which form an RNA-triple-helix adhesive scaffold upon interaction with dextran aldehyde, the latter able to chemically interact and adhere to natural tissue amines in the tumour. We also show that the self-assembled RNA-triple-helix conjugates remain functional in vitro and in vivo, and that they lead to nearly 90% levels of tumour shrinkage two weeks post-gel implantation in a triple-negative breast cancer mouse model. Our findings suggest that the RNA-triple-helix hydrogels can be used as an efficient anticancer platform to locally modulate the expression of endogenous miRs in cancer.

Strong contributions from vertical triads to helix-partner preferences in parallel coiled coils.

Science.gov (United States)

Steinkruger, Jay D; Bartlett, Gail J; Woolfson, Derek N; Gellman, Samuel H

2012-09-26

Pairing preferences in heterodimeric coiled coils are determined by complementarities among side chains that pack against one another at the helix-helix interface. However, relationships between dimer stability and interfacial residue identity are not fully understood. In the context of the "knobs-into-holes" (KIH) packing pattern, one can identify two classes of interactions between side chains from different helices: "lateral", in which a line connecting the adjacent side chains is perpendicular to the helix axes, and "vertical", in which the connecting line is parallel to the helix axes. We have previously analyzed vertical interactions in antiparallel coiled coils and found that one type of triad constellation (a'-a-a') exerts a strong effect on pairing preferences, while the other type of triad (d'-d-d') has relatively little impact on pairing tendencies. Here, we ask whether vertical interactions (d'-a-d') influence pairing in parallel coiled-coil dimers. Our results indicate that vertical interactions can exert a substantial impact on pairing specificity, and that the influence of the d'-a-d' triad depends on the lateral a' contact within the local KIH motif. Structure-informed bioinformatic analyses of protein sequences reveal trends consistent with the thermodynamic data derived from our experimental model system in suggesting that heterotriads involving Leu and Ile are preferred over homotriads involving Leu and Ile.

Testosterone-Fatty Acid esterification: a unique target for the endocrine toxicity of tributyltin to gastropods.

Science.gov (United States)

Leblanc, Gerald A; Gooding, Meredith P; Sternberg, Robin M

2005-01-01

Over the past thirty years, a global occurrence of sexual aberration has occurred whereby females among populations of prosobranch snails exhibit male sex characteristics. This condition, called imposex, has been causally associated with exposure to the biocide tributyltin. Tributyltin-exposed, imposex snails typically have elevated levels of testosterone which have led to the postulate that this endocrine dysfunction is responsible for imposex. This overview describes recent evidence that supports this postulate. Gastropods maintain circulating testosterone levels and administration of testosterone to females or castrates stimulates male sex differentiation in several snail species. Studies in the mud snail (Ilyanassa obsoleta) have shown that gastropods utilize a unique strategy for regulating free testosterone levels. Excess testosterone is converted to fatty acid esters by the action of a testosterone-inducible, high capacity/low affinity enzyme, acyl-CoA:testosterone acyl transferase, and stored within the organisms. Free testosterone levels are regulated during the reproductive cycle apparently due to changes in esterification/desterification suggesting that testosterone functions in the reproductive cycle of the organisms. Testosterone esterification provides a unique target in the testosterone regulatory machinery of snails that is altered by tributyltin. Indeed, imposex and free testosterone levels were elevated in field collected snails containing high tin levels, while testosterone-fatty acid ester pools were reduced in these organisms. These observations indicate that tributyltin elevates free testosterone by reducing the retention of testosterone as fatty acid-esters. This endocrine effect of tributyltin may be responsible for imposex.

What can triple helix frameworks offer to the analysis of eco-innovation dynamics? Theoretical and methodological considerations

DEFF Research Database (Denmark)

Yang, Yan; Holgaard, Jette Egelund; Remmen, Arne

2012-01-01

stakeholder groups are interacting in this connection. Taking the triple helix as the theoretical departure point, this paper discusses the opportunities offered by these triple helix frameworks for analyzing eco-innovation dynamics from both theoretical and practical perspectives. It adds to the debate about......Bringing environmental concerns into focus of innovation processes will in several cases also expand the numbers of actors involved. Eco-innovation and triple helix are often frameworks applied to analyse how environmental concerns are integrated in the innovation processes and how different...

Living Labs as boundary-spanners between Triple Helix actors

NARCIS (Netherlands)

van Geenhuizen, M.S.

2016-01-01

Living labs are an increasingly popular methodology to enhance innovation. Living labs aim to span boundaries between different organizations, among others Triple helix actors, by acting as a network organization typically in a real-life environment to foster co-creation by user-groups. This paper

The Triple Helix Model and the Knowledge-Based Economy

NARCIS (Netherlands)

Leydesdorff, L.; Meyer, M.

2010-01-01

The Triple Helix model of university-industry-government relations can be generalized from a neo-institutional model of networks of relations to a neo-evolutionary model of how three selection environments operate upon one another. Two selection mechanisms operating upon each other can mutually

Role of amphipathic helix of a herpesviral protein in membrane deformation and T cell receptor downregulation.

Directory of Open Access Journals (Sweden)

Chan-Ki Min

2008-11-01

Full Text Available Lipid rafts are membrane microdomains that function as platforms for signal transduction and membrane trafficking. Tyrosine kinase interacting protein (Tip of T lymphotropic Herpesvirus saimiri (HVS is targeted to lipid rafts in T cells and downregulates TCR and CD4 surface expression. Here, we report that the membrane-proximal amphipathic helix preceding Tip's transmembrane (TM domain mediates lipid raft localization and membrane deformation. In turn, this motif directs Tip's lysosomal trafficking and selective TCR downregulation. The amphipathic helix binds to the negatively charged lipids and induces liposome tubulation, the TM domain mediates oligomerization, and cooperation of the membrane-proximal helix with the TM domain is sufficient for localization to lipid rafts and lysosomal compartments, especially the mutivesicular bodies. These findings suggest that the membrane-proximal amphipathic helix and TM domain provide HVS Tip with the unique ability to deform the cellular membranes in lipid rafts and to downregulate TCRs potentially through MVB formation.

A rare polyglycine type II-like helix motif in naturally occurring proteins.

Science.gov (United States)

Warkentin, Eberhard; Weidenweber, Sina; Schühle, Karola; Demmer, Ulrike; Heider, Johann; Ermler, Ulrich

2017-11-01

Common structural elements in proteins such as α-helices or β-sheets are characterized by uniformly repeating, energetically favorable main chain conformations which additionally exhibit a completely saturated hydrogen-bonding network of the main chain NH and CO groups. Although polyproline or polyglycine type II helices (PP II or PG II ) are frequently found in proteins, they are not considered as equivalent secondary structure elements because they do not form a similar self-contained hydrogen-bonding network of the main chain atoms. In this context our finding of an unusual motif of glycine-rich PG II -like helices in the structure of the acetophenone carboxylase core complex is of relevance. These PG II -like helices form hexagonal bundles which appear to fulfill the criterion of a (largely) saturated hydrogen-bonding network of the main-chain groups and therefore may be regarded in this sense as a new secondary structure element. It consists of a central PG II -like helix surrounded by six nearly parallel PG II -like helices in a hexagonal array, plus an additional PG II -like helix extending the array outwards. Very related structural elements have previously been found in synthetic polyglycine fibers. In both cases, all main chain NH and CO groups of the central PG II -helix are saturated by either intra- or intermolecular hydrogen-bonds, resulting in a self-contained hydrogen-bonding network. Similar, but incomplete PG II -helix patterns were also previously identified in a GTP-binding protein and an antifreeze protein. © 2017 Wiley Periodicals, Inc.

Efficient Fatigue Analysis of Helix Elements in Umbilicals and Flexible Risers: Theory and Applications

Directory of Open Access Journals (Sweden)

Geir Skeie

2012-01-01

Full Text Available Fatigue analysis of structural components such as helix tensile armors and steel tubes is a critical design issue for dynamic umbilicals and flexible pipes. The basis for assessment of fatigue damage of such elements is the long-term stress cycle distribution at critical locations on the helix elements caused by long-term environmental loading on the system. The long-term stress cycle distribution will hence require global dynamic time domain analysis followed by a detailed cross-sectional analysis in a large number of irregular sea states. An overall computational consistent and efficient fatigue analysis scheme is outlined with due regard of the cross-sectional analysis technique required for fatigue stress calculation with particular attention to the helix elements. The global cross-section is exposed to pure bending, tensile, torsion, and pressure loading. The state of the different cross-section elements is based on the global response. Special emphasis is placed on assessment of friction stresses caused by the stick-slip behavior of helix elements in bending that are of special importance for fatigue life assessments. The described cross-sectional analysis techniques are based on an extensive literature survey and are hence considered to represent industry consensus. The performance of the described calculation scheme is illustrated by case studies.

Identification of a basic helix-loop-helix-type transcription regulator gene in Aspergillus oryzae by systematically deleting large chromosomal segments.

Science.gov (United States)

Jin, Feng Jie; Takahashi, Tadashi; Machida, Masayuki; Koyama, Yasuji

2009-09-01

We previously developed two methods (loop-out and replacement-type recombination) for generating large-scale chromosomal deletions that can be applied to more effective chromosomal engineering in Aspergillus oryzae. In this study, the replacement-type method is used to systematically delete large chromosomal DNA segments to identify essential and nonessential regions in chromosome 7 (2.93 Mb), which is the smallest A. oryzae chromosome and contains a large number of nonsyntenic blocks. We constructed 12 mutants harboring deletions that spanned 16- to 150-kb segments of chromosome 7 and scored phenotypic changes in the resulting mutants. Among the deletion mutants, strains designated Delta5 and Delta7 displayed clear phenotypic changes involving growth and conidiation. In particular, the Delta5 mutant exhibited vigorous growth and conidiation, potentially beneficial characteristics for certain industrial applications. Further deletion analysis allowed identification of the AO090011000215 gene as the gene responsible for the Delta5 mutant phenotype. The AO090011000215 gene was predicted to encode a helix-loop-helix binding protein belonging to the bHLH family of transcription factors. These results illustrate the potential of the approach for identifying novel functional genes.

Nonlinear time-dependent simulation of helix traveling wave tubes

International Nuclear Information System (INIS)

Peng Wei-Feng; Yang Zhong-Hai; Hu Yu-Lu; Li Jian-Qing; Lu Qi-Ru; Li Bin

2011-01-01

A one-dimensional nonlinear time-dependent theory for helix traveling wave tubes is studied. A generalized electromagnetic field is applied to the expression of the radio frequency field. To simulate the variations of the high frequency structure, such as the pitch taper and the effect of harmonics, the spatial average over a wavelength is substituted by a time average over a wave period in the equation of the radio frequency field. Under this assumption, the space charge field of the electron beam can be treated by a space charge wave model along with the space charge coefficient. The effects of the radio frequency and the space charge fields on the electrons are presented by the equations of the electron energy and the electron phase. The time-dependent simulation is compared with the frequency-domain simulation for a helix TWT, which validates the availability of this theory. (interdisciplinary physics and related areas of science and technology)

Analysis of eco-innovation with triple helix approach: case-study of biofloc catfish farming in Yogyakarta

Science.gov (United States)

Purwadi, D.; Nurlaily, I.

2018-03-01

Concerning environmental into focus of innovation process will expand the number of actor involved. Eco-innovation and triple helix are often frameworks applied to analyse how environmental concern are integrated in innovation process and how different stakeholder groups are having inter relation. Case study from biofloc catfish farming in Yogyakarta is presented to demonstrate a possible approach for researching the success of triple helix frameworks. This case is considered on basic of the result of a survey among farmers, academician and government. The paper concludes the creating of full triple helix encounters problem in practice. It also includes suggestion for further research on fisheries development.

Tunable single photonic defect-mode in cholesteric liquid crystals with laser-induced local modifications of helix

International Nuclear Information System (INIS)

Yoshida, Hiroyuki; Lee, Chee Heng; Fujii, Akihiko; Ozaki, Masanori

2006-01-01

The authors demonstrate a tunable single photonic defect-mode in a single cholesteric liquid crystal material based on a structural defect introduced by local modification of the helix. An unpolymerized region of cholesteric liquid crystal acting as the defect was left between two polymerized regions via a two-photon excitation laser-lithography process. Upon polymerization, the cholesteric liquid crystal helix elongated and became thermally stable, and a single photonic defect mode was exhibited due to the contrast in the helix pitch at the defect. The defect mode showed tunability upon heating, and a 36 nm redshift was seen over a temperature range of 30 deg. C

Kevlar: Transitioning Helix for Research to Practice

Science.gov (United States)

2016-03-01

x86 binaries, although it can be targeted to any platform that is targeted by IDA Pro. Currently, IDA Pro targets more than 40 processors and...effects its own transformations. Helix/Kevlar then automatically generates SPRI rules for any program variants by essentially performing a “ smart diff...execute permission on the pages of memory it uses, leaving only execute (but not write) permission on the code cache. Strata also watches for attempts

Stretched versus compressed exponential kinetics in α-helix folding

International Nuclear Information System (INIS)

Hamm, Peter; Helbing, Jan; Bredenbeck, Jens

2006-01-01

In a recent paper (J. Bredenbeck, J. Helbing, J.R. Kumita, G.A. Woolley, P. Hamm, α-helix formation in a photoswitchable peptide tracked from picoseconds to microseconds by time resolved IR spectroscopy, Proc. Natl. Acad. Sci USA 102 (2005) 2379), we have investigated the folding of a photo-switchable α-helix with a kinetics that could be fit by a stretched exponential function exp(-(t/τ) β ). The stretching factor β became smaller as the temperature was lowered, a result which has been interpreted in terms of activated diffusion on a rugged energy surface. In the present paper, we discuss under which conditions diffusion problems occur with stretched exponential kinetics (β 1). We show that diffusion problems do have a strong tendency to yield stretched exponential kinetics, yet, that there are conditions (strong perturbation from equilibrium, performing the experiment in the folding direction) under which compressed exponential kinetics would be expected instead. We discuss the kinetics on free energy surfaces predicted by simple initiation-propagation models (zipper models) of α-helix folding, as well as by folding funnel models. We show that our recent experiment has been performed under condition for which models with strong downhill driving force, such as the zipper model, would predict compressed, rather than stretched exponential kinetics, in disagreement with the experimental observation. We therefore propose that the free energy surface along a reaction coordinate that governs the folding kinetics must be relatively flat and has a shape similar to a 1D golf course. We discuss how this conclusion can be unified with the thermodynamically well established zipper model by introducing an additional kinetic reaction coordinate

Rotational symmetry and the transformation of innovation systems in a Triple Helix of university-industry-government relations

NARCIS (Netherlands)

Ivanova, I.A.; Leydesdorff, L.

2014-01-01

Using a mathematical model, we show that a Triple Helix (TH) system contains self-interaction, and therefore self-organization of innovations can be expected in waves, whereas a Double Helix (DH) remains determined by its linear constituents. (The mathematical model is fully elaborated in the

The triple helix of collagens - an ancient protein structure that enabled animal multicellularity and tissue evolution.

Science.gov (United States)

Fidler, Aaron L; Boudko, Sergei P; Rokas, Antonis; Hudson, Billy G

2018-04-09

The cellular microenvironment, characterized by an extracellular matrix (ECM), played an essential role in the transition from unicellularity to multicellularity in animals (metazoans), and in the subsequent evolution of diverse animal tissues and organs. A major ECM component are members of the collagen superfamily -comprising 28 types in vertebrates - that exist in diverse supramolecular assemblies ranging from networks to fibrils. Each assembly is characterized by a hallmark feature, a protein structure called a triple helix. A current gap in knowledge is understanding the mechanisms of how the triple helix encodes and utilizes information in building scaffolds on the outside of cells. Type IV collagen, recently revealed as the evolutionarily most ancient member of the collagen superfamily, serves as an archetype for a fresh view of fundamental structural features of a triple helix that underlie the diversity of biological activities of collagens. In this Opinion, we argue that the triple helix is a protein structure of fundamental importance in building the extracellular matrix, which enabled animal multicellularity and tissue evolution. © 2018. Published by The Company of Biologists Ltd.

Hydrated and Dehydrated Tertiary Interactions–Opening and Closing–of a Four-Helix Bundle Peptide

Science.gov (United States)

Lignell, Martin; Tegler, Lotta T.; Becker, Hans-Christian

2009-01-01

Abstract The structural heterogeneity and thermal denaturation of a dansyl-labeled four-helix bundle homodimeric peptide was studied with steady-state and time-resolved fluorescence spectroscopy and with circular dichroism (CD). At room temperature the fluorescence decay of the polarity-sensitive dansyl, located in the hydrophobic core region, can be described by a broad distribution of fluorescence lifetimes, reflecting the heterogeneous microenvironment. However, the lifetime distribution is nearly bimodal, which we ascribe to the presence of two major conformational subgroups. Since the fluorescence lifetime reflects the water content of the four-helix bundle conformations, we can use the lifetime analysis to monitor the change in hydration state of the hydrophobic core of the four-helix bundle. Increasing the temperature from 9°C to 23°C leads to an increased population of molten-globule-like conformations with a less ordered helical backbone structure. The fluorescence emission maximum remains constant in this temperature interval, and the hydrophobic core is not strongly affected. Above 30°C the structural dynamics involve transient openings of the four-helix bundle structure, as evidenced by the emergence of a water-quenched component and less negative CD. Above 60°C the homodimer starts to dissociate, as shown by the increasing loss of CD and narrow, short-lived fluorescence lifetime distributions. PMID:19619472

Increased helix and protein stability through the introduction of a new tertiary hydrogen bond.

Science.gov (United States)

Peterson, R W; Nicholson, E M; Thapar, R; Klevit, R E; Scholtz, J M

1999-03-12

In an effort to quantify the importance of hydrogen bonding and alpha-helix formation to protein stability, a capping box motif was introduced into the small phosphocarrier protein HPr. Previous studies had confirmed that Ser46, at the N-cap position of the short helix-B in HPr, serves as an N-cap in solution. Thus, only a single-site mutation was required to produce a canonical S-X-X-E capping box: Lys49 at the N3 position was substituted with a glutamic acid residue. Thermal and chemical denaturation studies on the resulting K49E HPr show that the designed variant is approximately 2 kcal mol-1 more stable than the wild-type protein. However, NMR studies indicate that the side-chain of Glu49 does not participate in the expected capping H-bond interaction, but instead forms a new tertiary H-bond that links helix-B to the four-stranded beta-sheet of HPr. Here, we demonstrate that a strategy in which new non-native H-bonds are introduced can generate proteins with increased stability. We discuss why the original capping box design failed, and compare the energetic consequences of the new tertiary side-chain to main-chain H-bond with a local (helix-capping) side-chain to main-chain H-bond on the protein's global stability. Copyright 1999 Academic Press.

Helix Nebula Science Cloud pilot phase open session

CERN Multimedia

CERN. Geneva

2018-01-01

This Helix Nebula Science Cloud (HNSciCloud) public session is open to everyone and will be webcast. The session will provide the audience with an overview of the HNSciCloud pre-commercial procurement project and the innovative cloud platforms that have been developed. A number of practical use-cases from the physics community will be presented as well as the next steps to be undertaken.

An amphipathic alpha-helix controls multiple roles of brome mosaic virus protein 1a in RNA replication complex assembly and function.

Directory of Open Access Journals (Sweden)

Ling Liu

2009-03-01

Full Text Available Brome mosaic virus (BMV protein 1a has multiple key roles in viral RNA replication. 1a localizes to perinuclear endoplasmic reticulum (ER membranes as a peripheral membrane protein, induces ER membrane invaginations in which RNA replication complexes form, and recruits and stabilizes BMV 2a polymerase (2a(Pol and RNA replication templates at these sites to establish active replication complexes. During replication, 1a provides RNA capping, NTPase and possibly RNA helicase functions. Here we identify in BMV 1a an amphipathic alpha-helix, helix A, and use NMR analysis to define its structure and propensity to insert in hydrophobic membrane-mimicking micelles. We show that helix A is essential for efficient 1a-ER membrane association and normal perinuclear ER localization, and that deletion or mutation of helix A abolishes RNA replication. Strikingly, mutations in helix A give rise to two dramatically opposite 1a function phenotypes, implying that helix A acts as a molecular switch regulating the intricate balance between separable 1a functions. One class of helix A deletions and amino acid substitutions markedly inhibits 1a-membrane association and abolishes ER membrane invagination, viral RNA template recruitment, and replication, but doubles the 1a-mediated increase in 2a(Pol accumulation. The second class of helix A mutations not only maintains efficient 1a-membrane association but also amplifies the number of 1a-induced membrane invaginations 5- to 8-fold and enhances viral RNA template recruitment, while failing to stimulate 2a(Pol accumulation. The results provide new insights into the pathways of RNA replication complex assembly and show that helix A is critical for assembly and function of the viral RNA replication complex, including its central role in targeting replication components and controlling modes of 1a action.

Comparative analysis of the mitochondrial genomes in gastropods

International Nuclear Information System (INIS)

Arquez, Moises; Uribe, Juan Esteban; Castro, Lyda Raquel

2012-01-01

In this work we presented a comparative analysis of the mitochondrial genomes in gastropods. Nucleotide and amino acids composition was calculated and a comparative visual analysis of the start and termination codons was performed. The organization of the genome was compared calculating the number of intergenic sequences, the location of the genes and the number of reorganized genes (breakpoints) in comparison with the sequence that is presumed to be ancestral for the group. In order to calculate variations in the rates of molecular evolution within the group, the relative rate test was performed. In spite of the differences in the size of the genomes, the amino acids number is conserved. The nucleotide and amino acid composition is similar between Vetigastropoda, Ceanogastropoda and Neritimorpha in comparison to Heterobranchia and Patellogastropoda. The mitochondrial genomes of the group are very compact with few intergenic sequences, the only exception is the genome of Patellogastropoda with 26,828 bp. Start codons of the Heterobranchia and Patellogastropoda are very variable and there is also an increase in genome rearrangements for these two groups. Generally, the hypothesis of constant rates of molecular evolution between the groups is rejected, except when the genomes of Caenogastropoda and Vetigastropoda are compared.

RelB and RelE of Escherichia coli Form a Tight Complex That Represses Transcription via The Ribbon-Helix-Helix Motif in RelB

DEFF Research Database (Denmark)

Overgaard, Martin; Borch, Jonas; Gerdes, Kenn

2009-01-01

RelB, the Ribbon-Helix-Helix (RHH) repressor encoded by the relBE toxin-antitoxin locus of Escherichia coli, forms a tight complex with RelE and thereby counteracts the mRNA cleavage activity of RelE. In addition, RelB dimers repress the strong relBE promoter and this repression by RelB is enhanced...... by RelE - that is - RelE functions as a transcriptional co-repressor. RelB is a Lon protease substrate and Lon is required both for activation of relBE transcription and for activation of the mRNA cleavage activity of RelE. Here we characterize the molecular interactions important for transcriptional...... motif recognizes four 6 bp repeats within the bipartite binding site. The spacing between each half-site was found to be essential for cooperative interactions between adjacently bound RelB dimers stabilized by the co-repressor RelE. Kinetic and stoichiometric measurements of the interaction between Rel...

From Family Based to Industrial Based Production: Local Economic Development Initiatives and the HELIX Model

Directory of Open Access Journals (Sweden)

Bartjan W Pennink

2013-01-01

Full Text Available To build a strong local economy, good practice tells us that each community should undertake a collaborative, strategically planned process to understand and then act upon its own strengths, weaknesses, opportunities and threats. From this perspective we start with the local communities but how is this related to the perspective from the Helix model in which three actors are explicitly introduced: the Government, the Industry and the Universities? The purpose of local economic development (LED is to build up the economic capacity of a local area to improve its economic future and the quality of life for all. To support  the Local Economic Development in remote areas,   a program  has been developed based on the LED frame work of the world bank. This approach and  the experiences over  the past years with this program are  described in the first part.  In the second part of the paper, We analyse work done with that program with the help of the social capital concept and the triple helix model.  In all cases it is important to pay attention to who is taken the initiative after the first move (and it is not always the governance as actor and for the triple helix we suggest  that the concepts of (national Government, Industry and University need a translation to Local Governance Agency, Cooperation or other ways of cooperation of local communities and Local Universities. Although a push from outside might help  a local region in development the endogenous factors are  also needed. Keywords: Triple Helix model, Local Economic Development, Local Actors, Double Triangle within the Helix Model

Scientific opinion on the risks for public health related to the presence of tetrodotoxin (TTX) and TTX analogues in marine bivalves and gastropods

DEFF Research Database (Denmark)

Petersen, Annette

Tetrodotoxin (TTX) and its analogues are produced by marine bacteria and have been detected in marine bivalves and gastropods from European waters. The European Commission asked EFSA for a scientific opinion on the risks to public health related to the presence of TTX and TTX analogues in marine...... bivalves and gastropods. The Panel on Contaminants in the Food Chain reviewed the available literature but did not find support for the minimum lethal dose for humans of 2 mg, mentioned in various reviews. Some human case reports describe serious effects at a dose of 0.2 mg, corresponding to 4 μg/kg body...... weight (bw). However, the uncertainties on the actual exposure in the studies preclude their use for derivation of an acute reference dose (ARfD). Instead, a group ARfD of 0.25 μg/kg bw, applying to TTX and its analogues, was derived based on a TTX dose of 25 μg/kg bw at which no apathy was observed...

Larval trematode infections in freshwater gastropods from the Albufera Natural Park in Spain.

Science.gov (United States)

Toledo, R; Muñoz-Antolí, C; Pérez, M; Esteban, J G

1998-03-01

Malacological samplings were made from January 1994 to December 1996 in the Albufera Natural Park (Valencia, Spain) to trace the dynamics of molluscan populations and the prevalence and intensity of infection by larval trematodes. A total of 10,533 freshwater gastropods belonging to seven species (Lymnaea auricularia, L. truncatula, L. palustris, L. peregra, Bithynia tentaculata, Physa acuta and Gyraulus chinensis) was examined, and 110 (1.04%) were found to harbour some of the nine distinguishable types of cercariae, namely four echinostome cercariae (Hypoderaeum conoideum, Echinoparyphium recurvatum, Euparyphium albuferensis, and Echinostoma sp.), four furcocercous cercariae, and one xiphidiocercous cercaria. This study shows that the composition of the snail and trematode communities may be determined by the particular environmental conditions present and the human intervention in the area.

Loop-to-helix transition in the structure of multidrug regulator AcrR at the entrance of the drug-binding cavity

Energy Technology Data Exchange (ETDEWEB)

Manjasetty, Babu A.; Halavaty, Andrei S.; Luan, Chi-Hao; Osipiuk, Jerzy; Mulligan, Rory; Kwon, Keehwan; Anderson, Wayne F.; Joachimiak, Andrzej

2016-04-01

Multidrug transcription regulator AcrR from Salmonella enterica subsp. enterica serovar Typhimurium str. LT2 belongs to the tetracycline repressor family, one of the largest groups of bacterial transcription factors. The crystal structure of dimeric AcrR was determined and refined to 1.56 Å resolution. The tertiary and quaternary structures of AcrR are similar to those of its homologs. The multidrug binding site was identified based on structural alignment with homologous proteins and has a di(hydroxyethyl)ether molecule bound. Residues from helices a4 and a7 shape the entry into this binding site. The structure of AcrR reveals that the extended helical conformation of helix a4 is stabilized by the hydrogen bond between Glu67 (helix a4) and Gln130 (helix a7). Based on the structural comparison with the closest homolog structure, the Escherichia coli AcrR, we propose that this hydrogen bond is responsible for control of the loop-to-helix transition within helix a4. This local conformational switch of helix a4 may be a key step in accessing the multidrug binding site and securing ligands at the binding site. Solution smallmolecule binding studies suggest that AcrR binds ligands with their core chemical structure resembling the tetracyclic ring of cholesterol.

Structural studies of polypeptides: Mechanism of immunoglobin catalysis and helix propagation in hybrid sequence, disulfide containing peptides

Energy Technology Data Exchange (ETDEWEB)

Storrs, Richard Wood [Univ. of California, Berkeley, CA (United States)

1992-08-01

Catalytic immunoglobin fragments were studied Nuclear Magnetic Resonance spectroscopy to identify amino acid residues responsible for the catalytic activity. Small, hybrid sequence peptides were analyzed for helix propagation following covalent initiation and for activity related to the protein from which the helical sequence was derived. Hydrolysis of p-nitrophenyl carbonates and esters by specific immunoglobins is thought to involve charge complementarity. The pK of the transition state analog P-nitrophenyl phosphate bound to the immunoglobin fragment was determined by ³¹P-NMR to verify the juxtaposition of a positively charged amino acid to the binding/catalytic site. Optical studies of immunoglobin mediated photoreversal of cis, syn cyclobutane thymine dimers implicated tryptophan as the photosensitizing chromophore. Research shows the chemical environment of a single tryptophan residue is altered upon binding of the thymine dimer. This tryptophan residue was localized to within 20 Å of the binding site through the use of a nitroxide paramagnetic species covalently attached to the thymine dimer. A hybrid sequence peptide was synthesized based on the bee venom peptide apamin in which the helical residues of apamin were replaced with those from the recognition helix of the bacteriophage 434 repressor protein. Oxidation of the disufide bonds occured uniformly in the proper 1-11, 3-15 orientation, stabilizing the 434 sequence in an α-helix. The glycine residue stopped helix propagation. Helix propagation in 2,2,2-trifluoroethanol mixtures was investigated in a second hybrid sequence peptide using the apamin-derived disulfide scaffold and the S-peptide sequence. The helix-stop signal previously observed was not observed in the NMR NOESY spectrum. Helical connectivities were seen throughout the S-peptide sequence. The apamin/S-peptide hybrid binded to the S-protein (residues 21-166 of ribonuclease A) and reconstituted enzymatic activity.

Structural studies of polypeptides: Mechanism of immunoglobin catalysis and helix propagation in hybrid sequence, disulfide containing peptides

Energy Technology Data Exchange (ETDEWEB)

Storrs, R.W.

1992-08-01

Catalytic immunoglobin fragments were studied Nuclear Magnetic Resonance spectroscopy to identify amino acid residues responsible for the catalytic activity. Small, hybrid sequence peptides were analyzed for helix propagation following covalent initiation and for activity related to the protein from which the helical sequence was derived. Hydrolysis of p-nitrophenyl carbonates and esters by specific immunoglobins is thought to involve charge complementarity. The pK of the transition state analog P-nitrophenyl phosphate bound to the immunoglobin fragment was determined by [sup 31]P-NMR to verify the juxtaposition of a positively charged amino acid to the binding/catalytic site. Optical studies of immunoglobin mediated photoreversal of cis, syn cyclobutane thymine dimers implicated tryptophan as the photosensitizing chromophore. Research shows the chemical environment of a single tryptophan residue is altered upon binding of the thymine dimer. This tryptophan residue was localized to within 20 [Angstrom] of the binding site through the use of a nitroxide paramagnetic species covalently attached to the thymine dimer. A hybrid sequence peptide was synthesized based on the bee venom peptide apamin in which the helical residues of apamin were replaced with those from the recognition helix of the bacteriophage 434 repressor protein. Oxidation of the disufide bonds occured uniformly in the proper 1-11, 3-15 orientation, stabilizing the 434 sequence in an [alpha]-helix. The glycine residue stopped helix propagation. Helix propagation in 2,2,2-trifluoroethanol mixtures was investigated in a second hybrid sequence peptide using the apamin-derived disulfide scaffold and the S-peptide sequence. The helix-stop signal previously observed was not observed in the NMR NOESY spectrum. Helical connectivities were seen throughout the S-peptide sequence. The apamin/S-peptide hybrid binded to the S-protein (residues 21-166 of ribonuclease A) and reconstituted enzymatic activity.

Extreme bendability of DNA double helix due to bending asymmetry

NARCIS (Netherlands)

Salari, H.; Eslami-Mossallam, B.; Nederi, S.; Ejtehadi, M.R.

2015-01-01

Experimental data of the DNA cyclization (J-factor) at short length scales exceed the theoretical expectation based on the wormlike chain (WLC) model by several orders of magnitude. Here, we propose that asymmetric bending rigidity of the double helix in the groove direction can be responsible for

An Amphipathic Helix Directs Cellular Membrane Curvature Sensing and Function of the BAR Domain Protein PICK1.

Science.gov (United States)

Herlo, Rasmus; Lund, Viktor K; Lycas, Matthew D; Jansen, Anna M; Khelashvili, George; Andersen, Rita C; Bhatia, Vikram; Pedersen, Thomas S; Albornoz, Pedro B C; Johner, Niklaus; Ammendrup-Johnsen, Ina; Christensen, Nikolaj R; Erlendsson, Simon; Stoklund, Mikkel; Larsen, Jannik B; Weinstein, Harel; Kjærulff, Ole; Stamou, Dimitrios; Gether, Ulrik; Madsen, Kenneth L

2018-05-15

BAR domains are dimeric protein modules that sense, induce, and stabilize lipid membrane curvature. Here, we show that membrane curvature sensing (MCS) directs cellular localization and function of the BAR domain protein PICK1. In PICK1, and the homologous proteins ICA69 and arfaptin2, we identify an amphipathic helix N-terminal to the BAR domain that mediates MCS. Mutational disruption of the helix in PICK1 impaired MCS without affecting membrane binding per se. In insulin-producing INS-1E cells, super-resolution microscopy revealed that disruption of the helix selectively compromised PICK1 density on insulin granules of high curvature during their maturation. This was accompanied by reduced hormone storage in the INS-1E cells. In Drosophila, disruption of the helix compromised growth regulation. By demonstrating size-dependent binding on insulin granules, our finding highlights the function of MCS for BAR domain proteins in a biological context distinct from their function, e.g., at the plasma membrane during endocytosis. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

One-dimensional nonlinear theory for rectangular helix traveling-wave tube

Energy Technology Data Exchange (ETDEWEB)

Fu, Chengfang, E-mail: fchffchf@126.com; Zhao, Bo; Yang, Yudong; Ju, Yongfeng [Faculty of Electronic Information Engineering, Huaiyin Institute of Technology, Huai' an 223003 (China); Wei, Yanyu [School of Physical Electronics, University of Electronic and Technology of China, Chengdu 610054 (China)

2016-08-15

A 1-D nonlinear theory of a rectangular helix traveling-wave tube (TWT) interacting with a ribbon beam is presented in this paper. The RF field is modeled by a transmission line equivalent circuit, the ribbon beam is divided into a sequence of thin rectangular electron discs with the same cross section as the beam, and the charges are assumed to be uniformly distributed over these discs. Then a method of computing the space-charge field by solving Green's Function in the Cartesian Coordinate-system is fully described. Nonlinear partial differential equations for field amplitudes and Lorentz force equations for particles are solved numerically using the fourth-order Runge-Kutta technique. The tube's gain, output power, and efficiency of the above TWT are computed. The results show that increasing the cross section of the ribbon beam will improve a rectangular helix TWT's efficiency and reduce the saturated length.

Clear cell hidradenocarcinoma of the ear helix: report of primary ear helix adnexal carcinoma with regional lymph node metastasis.

Science.gov (United States)

Bae, Tae Hui; Kang, Shin Hyuk; Kim, Han Koo; Kim, Woo Seob; Kim, Mi Kyung

2014-07-01

Clear cell hidradenocarcinoma is a rare tumor of eccrine sweat gland origin that has a predilection for the head and neck. It has an indolent growth pattern and a higher incidence of regional and distant metastases. Metastasizing adnexal carcinomas are rare; thus, currently there is no uniform treatment guideline. We report a case of an 89-year-old female patient with clear cell hidradenocarcinoma manifesting in the right ear helix that metastasized to the right parotid gland who was treated by wide local excision and radiation therapy.

The Effect of a Helix-Coil Transition on the Extension Elasticity

Science.gov (United States)

Buhot, Arnaud; Halperin, Avi

2000-03-01

The secondary structure of a polymer affects its deformation behavior in accordance with the Le Chatelier principle. An important example of such secondary structure is the alpha helix encountered in polypeptides. Similar structure was recently proposed for PEO in aqueous media. Our discussion concerns the coupling of the cooperative helix-coil transition and the extension elasticity. In particular, we analyze the extension of a long single chain by use of optical tweezers or AFM. We consider chains that exist in the coil-state when unperturbed. The transition nevertheless occurs because the extension favors the low entropy helical state. As a result, the corresponding force law exhibits a plateau. The analysis of this situation involves two ingredients: (I) the stretching free energy penalty for a rod-coil mutiblock copolymer (II) the entropy associated with the possible placements of the rod and coil blocks.

Chiral transformation: From single nanowire to double helix

KAUST Repository

Wang, Yong

2011-12-21

We report a new type of water-soluble ultrathin Au-Ag alloy nanowire (NW), which exhibits unprecedented behavior in a colloidal solution. Upon growth of a thin metal (Pd, Pt, or Au) layer, the NW winds around itself to give a metallic double helix. We propose that the winding originates from the chirality within the as-synthesized Au-Ag NWs, which were induced to untwist upon metal deposition. © 2011 American Chemical Society.

A Helix-Stabilizing Linker Improves Subcutaneous Bioavailability of a Helical Peptide Independent of Linker Lipophilicity

Science.gov (United States)

Zhang, Liang; Navaratna, Tejas; Thurber, Greg M.

2016-01-01

Stabilized peptides address several limitations to peptide-based imaging agents and therapeutics such as poor stability and low affinity due to conformational flexibility. There is also active research in developing these compounds for intracellular drug targeting, and significant efforts have been invested to determine the effects of helix stabilization on intracellular delivery. However, much less is known about the impact on other pharmacokinetic parameters such as plasma clearance and bioavailability. We investigated the effect of different fluorescent helix-stabilizing linkers with varying lipophilicity on subcutaneous (SC) bioavailability using the glucagon-like peptide-1 (GLP-1) receptor ligand exendin as a model system. The stabilized peptides showed significantly higher protease resistance and increased bioavailability independent of linker hydrophilicity, and all subcutaneously delivered conjugates were able to successfully target the islets of Langerhans with high specificity. The lipophilic peptide variants had slower absorption and plasma clearance than their respective hydrophilic conjugates, and the absolute bioavailability was also lower likely due to the longer residence times in the skin. The ease and efficiency of double-click helix stabilization chemistries is a useful tool for increasing the bioavailability of peptide therapeutics, many of which suffer from rapid in vivo protease degradation. Helix stabilization using linkers of varying lipophilicity can further control SC absorption and clearance rates to customize plasma pharmacokinetics. PMID:27327034

The human early-life exposome (HELIX): project rationale and design.

Science.gov (United States)

Vrijheid, Martine; Slama, Rémy; Robinson, Oliver; Chatzi, Leda; Coen, Muireann; van den Hazel, Peter; Thomsen, Cathrine; Wright, John; Athersuch, Toby J; Avellana, Narcis; Basagaña, Xavier; Brochot, Celine; Bucchini, Luca; Bustamante, Mariona; Carracedo, Angel; Casas, Maribel; Estivill, Xavier; Fairley, Lesley; van Gent, Diana; Gonzalez, Juan R; Granum, Berit; Gražulevičienė, Regina; Gutzkow, Kristine B; Julvez, Jordi; Keun, Hector C; Kogevinas, Manolis; McEachan, Rosemary R C; Meltzer, Helle Margrete; Sabidó, Eduard; Schwarze, Per E; Siroux, Valérie; Sunyer, Jordi; Want, Elizabeth J; Zeman, Florence; Nieuwenhuijsen, Mark J

2014-06-01

Developmental periods in early life may be particularly vulnerable to impacts of environmental exposures. Human research on this topic has generally focused on single exposure-health effect relationships. The "exposome" concept encompasses the totality of exposures from conception onward, complementing the genome. The Human Early-Life Exposome (HELIX) project is a new collaborative research project that aims to implement novel exposure assessment and biomarker methods to characterize early-life exposure to multiple environmental factors and associate these with omics biomarkers and child health outcomes, thus characterizing the "early-life exposome." Here we describe the general design of the project. In six existing birth cohort studies in Europe, HELIX will estimate prenatal and postnatal exposure to a broad range of chemical and physical exposures. Exposure models will be developed for the full cohorts totaling 32,000 mother-child pairs, and biomarkers will be measured in a subset of 1,200 mother-child pairs. Nested repeat-sampling panel studies (n = 150) will collect data on biomarker variability, use smartphones to assess mobility and physical activity, and perform personal exposure monitoring. Omics techniques will determine molecular profiles (metabolome, proteome, transcriptome, epigenome) associated with exposures. Statistical methods for multiple exposures will provide exposure-response estimates for fetal and child growth, obesity, neurodevelopment, and respiratory outcomes. A health impact assessment exercise will evaluate risks and benefits of combined exposures. HELIX is one of the first attempts to describe the early-life exposome of European populations and unravel its relation to omics markers and health in childhood. As proof of concept, it will form an important first step toward the life-course exposome.

Right- and left-handed three-helix proteins. I. Experimental and simulation analysis of differences in folding and structure.

Science.gov (United States)

Glyakina, Anna V; Pereyaslavets, Leonid B; Galzitskaya, Oxana V

2013-09-01

Despite the large number of publications on three-helix protein folding, there is no study devoted to the influence of handedness on the rate of three-helix protein folding. From the experimental studies, we make a conclusion that the left-handed three-helix proteins fold faster than the right-handed ones. What may explain this difference? An important question arising in this paper is whether the modeling of protein folding can catch the difference between the protein folding rates of proteins with similar structures but with different folding mechanisms. To answer this question, the folding of eight three-helix proteins (four right-handed and four left-handed), which are similar in size, was modeled using the Monte Carlo and dynamic programming methods. The studies allowed us to determine the orders of folding of the secondary-structure elements in these domains and amino acid residues which are important for the folding. The obtained data are in good correlation with each other and with the experimental data. Structural analysis of these proteins demonstrated that the left-handed domains have a lesser number of contacts per residue and a smaller radius of cross section than the right-handed domains. This may be one of the explanations of the observed fact. The same tendency is observed for the large dataset consisting of 332 three-helix proteins (238 right- and 94 left-handed). From our analysis, we found that the left-handed three-helix proteins have some less-dense packing that should result in faster folding for some proteins as compared to the case of right-handed proteins. Copyright © 2013 Wiley Periodicals, Inc.

Loop-to-helix transition in the structure of multidrug regulator AcrR at the entrance of the drug-binding cavity.

Science.gov (United States)

Manjasetty, Babu A; Halavaty, Andrei S; Luan, Chi-Hao; Osipiuk, Jerzy; Mulligan, Rory; Kwon, Keehwan; Anderson, Wayne F; Joachimiak, Andrzej

2016-04-01

Multidrug transcription regulator AcrR from Salmonella enterica subsp. enterica serovar Typhimurium str. LT2 belongs to the tetracycline repressor family, one of the largest groups of bacterial transcription factors. The crystal structure of dimeric AcrR was determined and refined to 1.56Å resolution. The tertiary and quaternary structures of AcrR are similar to those of its homologs. The multidrug binding site was identified based on structural alignment with homologous proteins and has a di(hydroxyethyl)ether molecule bound. Residues from helices α4 and α7 shape the entry into this binding site. The structure of AcrR reveals that the extended helical conformation of helix α4 is stabilized by the hydrogen bond between Glu67 (helix α4) and Gln130 (helix α7). Based on the structural comparison with the closest homolog structure, the Escherichia coli AcrR, we propose that this hydrogen bond is responsible for control of the loop-to-helix transition within helix α4. This local conformational switch of helix α4 may be a key step in accessing the multidrug binding site and securing ligands at the binding site. Solution small-molecule binding studies suggest that AcrR binds ligands with their core chemical structure resembling the tetracyclic ring of cholesterol. Copyright © 2016. Published by Elsevier Inc.

An unusual helix-turn-helix protease inhibitory motif in a novel trypsin inhibitor from seeds of Veronica (Veronica hederifolia L.).

Science.gov (United States)

Conners, Rebecca; Konarev, Alexander V; Forsyth, Jane; Lovegrove, Alison; Marsh, Justin; Joseph-Horne, Timothy; Shewry, Peter; Brady, R Leo

2007-09-21

The storage tissues of many plants contain protease inhibitors that are believed to play an important role in defending the plant from invasion by pests and pathogens. These proteinaceous inhibitor molecules belong to a number of structurally distinct families. We describe here the isolation, purification, initial inhibitory properties, and three-dimensional structure of a novel trypsin inhibitor from seeds of Veronica hederifolia (VhTI). The VhTI peptide inhibits trypsin with a submicromolar apparent K(i) and is expected to be specific for trypsin-like serine proteases. VhTI differs dramatically in structure from all previously described families of trypsin inhibitors, consisting of a helix-turn-helix motif, with the two alpha helices tightly associated by two disulfide bonds. Unusually, the crystallized complex is in the form of a stabilized acyl-enzyme intermediate with the scissile bond of the VhTI inhibitor cleaved and the resulting N-terminal portion of the inhibitor remaining attached to the trypsin catalytic serine 195 by an ester bond. A synthetic, truncated version of the VhTI peptide has also been produced and co-crystallized with trypsin but, surprisingly, is seen to be uncleaved and consequently forms a noncovalent complex with trypsin. The VhTI peptide shows that effective enzyme inhibitors can be constructed from simple helical motifs and provides a new scaffold on which to base the design of novel serine protease inhibitors.

Genome-wide analysis of basic/helix-loop-helix gene family in peanut and assessment of its roles in pod development.

Directory of Open Access Journals (Sweden)

Chao Gao

Full Text Available The basic/helix-loop-helix (bHLH proteins constitute a superfamily of transcription factors that are known to play a range of regulatory roles in eukaryotes. Over the past few decades, many bHLH family genes have been well-characterized in model plants, such as Arabidopsis, rice and tomato. However, the bHLH protein family in peanuts has not yet been systematically identified and characterized. Here, 132 and 129 bHLH proteins were identified from two wild ancestral diploid subgenomes of cultivated tetraploid peanuts, Arachis duranensis (AA and Arachis ipaensis (BB, respectively. Phylogenetic analysis indicated that these bHLHs could be classified into 19 subfamilies. Distribution mapping results showed that peanut bHLH genes were randomly and unevenly distributed within the 10 AA chromosomes and 10 BB chromosomes. In addition, 120 bHLH gene pairs between the AA-subgenome and BB-subgenome were found to be orthologous and 101 of these pairs were highly syntenic in AA and BB chromosomes. Furthermore, we confirmed that 184 bHLH genes expressed in different tissues, 22 of which exhibited tissue-specific expression. Meanwhile, we identified 61 bHLH genes that may be potentially involved in peanut-specific subterranean. Our comprehensive genomic analysis provides a foundation for future functional dissection and understanding of the regulatory mechanisms of bHLH transcription factors in peanuts.

Salt- and pH-Triggered Helix-Coil Transition of Ionic Polypeptides under Physiology Conditions.

Science.gov (United States)

Yuan, Jingsong; Zhang, Yi; Sun, Yue; Cai, Zhicheng; Yang, Lijiang; Lu, Hua

2018-06-11

Controlling the helix-coil transition of polypeptides under physiological conditions is an attractive way toward smart functional materials. Here, we report the synthesis of a series of tertiary amine-functionalized ethylene glycol (EG x )-linked polypeptide electrolytes with their secondary structures tunable under physiological conditions. The resultant polymers, denoted as P(EG x DMA-Glu) ( x = 1, 2, and 3), show excellent aqueous solubility (>20 mg/mL) regardless of their charge states. Unlike poly-l-lysine that can form a helix only at pH above 10, P(EG x DMA-Glu) undergo a pH-dependent helix-coil switch with their transition points within the physiological range (pH ∼5.3-6.5). Meanwhile, P(EG x DMA-Glu) exhibit an unusual salt-induced helical conformation presumably owing to the unique properties of EG x linkers. Together, the current work highlights the importance of fine-tuning the linker chemistry in achieving conformation-switchable polypeptides and represents a facile approach toward stimuli-responsive biopolymers for advanced biological applications.

Ruby-Helix: an implementation of helical image processing based on object-oriented scripting language.

Science.gov (United States)

Metlagel, Zoltan; Kikkawa, Yayoi S; Kikkawa, Masahide

2007-01-01

Helical image analysis in combination with electron microscopy has been used to study three-dimensional structures of various biological filaments or tubes, such as microtubules, actin filaments, and bacterial flagella. A number of packages have been developed to carry out helical image analysis. Some biological specimens, however, have a symmetry break (seam) in their three-dimensional structure, even though their subunits are mostly arranged in a helical manner. We refer to these objects as "asymmetric helices". All the existing packages are designed for helically symmetric specimens, and do not allow analysis of asymmetric helical objects, such as microtubules with seams. Here, we describe Ruby-Helix, a new set of programs for the analysis of "helical" objects with or without a seam. Ruby-Helix is built on top of the Ruby programming language and is the first implementation of asymmetric helical reconstruction for practical image analysis. It also allows easier and semi-automated analysis, performing iterative unbending and accurate determination of the repeat length. As a result, Ruby-Helix enables us to analyze motor-microtubule complexes with higher throughput to higher resolution.

Structure of the Membrane Anchor of Pestivirus Glycoprotein Erns, a Long Tilted Amphipathic Helix

Science.gov (United States)

Aberle, Daniel; Muhle-Goll, Claudia; Bürck, Jochen; Wolf, Moritz; Reißer, Sabine; Luy, Burkhard; Wenzel, Wolfgang; Ulrich, Anne S.; Meyers, Gregor

2014-01-01

Erns is an essential virion glycoprotein with RNase activity that suppresses host cellular innate immune responses upon being partially secreted from the infected cells. Its unusual C-terminus plays multiple roles, as the amphiphilic helix acts as a membrane anchor, as a signal peptidase cleavage site, and as a retention/secretion signal. We analyzed the structure and membrane binding properties of this sequence to gain a better understanding of the underlying mechanisms. CD spectroscopy in different setups, as well as Monte Carlo and molecular dynamics simulations confirmed the helical folding and showed that the helix is accommodated in the amphiphilic region of the lipid bilayer with a slight tilt rather than lying parallel to the surface. This model was confirmed by NMR analyses that also identified a central stretch of 15 residues within the helix that is fully shielded from the aqueous layer, which is C-terminally followed by a putative hairpin structure. These findings explain the strong membrane binding of the protein and provide clues to establishing the Erns membrane contact, processing and secretion. PMID:24586172

SclR, a basic helix-loop-helix transcription factor, regulates hyphal morphology and promotes sclerotial formation in Aspergillus oryzae.

Science.gov (United States)

Jin, Feng Jie; Takahashi, Tadashi; Matsushima, Ken-ichiro; Hara, Seiichi; Shinohara, Yasutomo; Maruyama, Jun-ichi; Kitamoto, Katsuhiko; Koyama, Yasuji

2011-07-01

Most known basic-region helix-loop-helix (bHLH) proteins belong to a superfamily of transcription factors often involved in the control of growth and differentiation. Therefore, inappropriate expression of genes encoding bHLH proteins is frequently associated with developmental dysfunction. In our previously reported study, a novel bHLH protein-encoding gene (AO090011000215) of Aspergillus oryzae was identified. The gene-disrupted strain was found to produce dense conidia, but sparse sclerotia, relative to the parent strain. Here, to further analyze its function, we generated an overexpressing strain using the A. oryzae amyB gene promoter. Genetic overexpression led to a large number of initial hyphal aggregations and then the formation of mature sclerotia; it was therefore designated sclR (sclerotium regulator). At the same time, the sclR-overexpressing strain also displayed both delayed and decreased conidiation. Scanning electron microscopy indicated that the aerial hyphae of the sclR-overexpressing strain were extremely branched and intertwined with each other. In the generation of the SclR-enhanced green fluorescent protein (EGFP) expression strain, the SclR-EGFP protein fusion was conditionally detected in the nuclei. In addition, the loss of sclR function led to rapid protein degradation and cell lysis in dextrin-polypeptone-yeast extract liquid medium. Taken together, these observations indicate that SclR plays an important role in hyphal morphology, asexual conidiospore formation, and the promotion of sclerotial production, even retaining normal cell function, at least in submerged liquid culture.

Health and Environment Linked for Information Exchange in Atlanta (HELIX-Atlanta): A Pilot Tracking System

Science.gov (United States)

Rickman, Doug; Shire, J.; Qualters, J.; Mitchell, K.; Pollard, S.; Rao, R.; Kajumba, N.; Quattrochi, D.; Estes, M., Jr.; Meyer, P.;

Inventory of Selected Freshwater-Ecology Studies From the New England Coastal Basins (Maine, New Hampshire, Massachusetts, Rhode Island), 1937-1997

Science.gov (United States)

1999-01-01

Maine: Ecotoxicology and Environmental Safety, v. 25, no. 2, p. 244-252. 43 Gleich, J.G., 1972, Terrestrial gastropods from central Maine... macrophytes for our evaluation; because birds are not a focus of NAWQA activities, studies exclusively concerning waterfowl were not presented in this

Freshwater Biogeography and Limnological Evolution of the Tibetan Plateau - Insights from a Plateau-Wide Distributed Gastropod Taxon (Radix spp.)

Science.gov (United States)

von Oheimb, Parm Viktor; Albrecht, Christian; Riedel, Frank; Du, Lina; Yang, Junxing; Aldridge, David C.; Bößneck, Ulrich; Zhang, Hucai; Wilke, Thomas

2011-01-01

Background The Tibetan Plateau is not only the highest and largest plateau on earth; it is also home to numerous freshwater lakes potentially harbouring endemic faunal elements. As it remains largely unknown whether these lakes have continuously existed during the Last Glacial Maximum (LGM), questions arise as to whether taxa have been able to exist on the plateau since before the latest Pleistocene, from where and how often the plateau was colonized, and by which mechanisms organisms conquered remote high altitude lentic freshwater systems. In this study, species of the plateau-wide distributed freshwater gastropod genus Radix are used to answer these biogeographical questions. Methodology/Principal Findings Based on a broad spatial sampling of Radix spp. on the Tibetan Plateau, and phylogenetic analyses of mtDNA sequence data, three probably endemic and one widespread major Radix clade could be identified on the plateau. Two of the endemic clades show a remarkably high genetic diversity, indicating a relatively great phylogenetic age. Phylogeographical analyses of individuals belonging to the most widely distributed clade indicate that intra-plateau distribution cannot be explained by drainage-related dispersal alone. Conclusions/Significance Our study reveals that Radix spp. persisted throughout the LGM on the Tibetan Plateau. Therefore, we assume the continuous existence of suitable water bodies during that time. The extant Radix diversity on the plateau might have been caused by multiple colonization events combined with a relatively long intra-plateau evolution. At least one colonization event has a Palaearctic origin. In contrast to freshwater fishes, passive dispersal, probably by water birds, might be an important mechanism for conquering remote areas on the plateau. Patterns found in Radix spp. are shared with some terrestrial plateau taxa, indicating that Radix may be a suitable model taxon for inferring general patterns of biotic origin, dispersal and

Defining the structural requirements for a helix in 23 S ribosomal RNA that confers erythromycin resistance

DEFF Research Database (Denmark)

Douthwaite, S; Powers, T; Lee, J Y

1989-01-01

The helix spanning nucleotides 1198 to 1247 (helix 1200-1250) in Escherichia coli 23 S ribosomal RNA (rRNA) is functionally important in protein synthesis, and deletions in this region confer erythromycin resistance. In order to define the structural requirements for resistance, we have dissected...... deletion mutants show a sensitive phenotype. Deletions that extend into the base-pairing between GCC1208 and GGU1240 result in non-functional 23 S RNAs, which consequently do not confer resistance. A number of phylogenetically conserved nucleotides have been shown to be non-essential for 23 S RNA function....... However, removal of either these or non-conserved nucleotides from helix 1200-1250 measurably reduces the efficiency of 23 S RNA in forming functional ribosomes. We have used chemical probing and a modified primer extension method to investigate erythromycin binding to wild-type and resistant ribosomes...

Use of 1–4 interaction scaling factors to control the conformational equilibrium between α-helix and β-strand

International Nuclear Information System (INIS)

Pang, Yuan-Ping

2015-01-01

Highlights: • 1–4 interaction scaling factors are used to adjust conformational energy. • This article reports the effects of these factors on protein conformations. • Reducing these factors changes a helix to a strand in molecular dynamics simulation. • Increasing these factors causes the reverse conformational change. • These factors control the conformational equilibrium between helix and strand. - Abstract: 1–4 interaction scaling factors are used in AMBER forcefields to reduce the exaggeration of short-range repulsion caused by the 6–12 Lennard-Jones potential and a nonpolarizable charge model and to obtain better agreements of small-molecule conformational energies with experimental data. However, the effects of these scaling factors on protein secondary structure conformations have not been investigated until now. This article reports the finding that the 1–4 interactions among the protein backbone atoms separated by three consecutive covalent bonds are more repulsive in the α-helix conformation than in two β-strand conformations. Therefore, the 1–4 interaction scaling factors of protein backbone torsions ϕ and ψ control the conformational equilibrium between α-helix and β-strand. Molecular dynamics simulations confirm that reducing the ϕ and ψ scaling factors readily converts the α-helix conformation of AcO-(AAQAA) 3 -NH 2 to a β-strand conformation, and the reverse occurs when these scaling factors are increased. These results suggest that the ϕ and ψ scaling factors can be used to generate the α-helix or β-strand conformation in situ and to control the propensities of a forcefield for adopting secondary structure elements

Food availability and predation risk drive the distributional patterns of two pulmonate gastropods in a mangrove-saltmarsh transitional habitat.

Science.gov (United States)

Peng, Yisheng; Zhang, Min; Lee, Shing Yip

2017-09-01

The pulmonate gastropods, Phallomedusa solida (Martens, 1878) and Ophicardelus ornatus (Férussac, 1821), exhibit characteristic distributional patterns at the upper intertidal zones in estuarine mangrove and saltmarsh habitats on the eastern Australian coast. Past studies suggested inundation condition, soil salinity, and percent of vegetation cover were responsible for these patterns. In this study, the role of environmental parameters, food availability, physical stress, and predation pressure in determining the distributional patterns of these gastropods was evaluated along transects spanning saltmarsh, mangrove, and the ecotone habitats. For both species, the maximum population abundance occurred in the upper saltmarsh and the ecotone between mangrove and saltmarsh at 361.0 and 358.0 ind.m -2 , respectively, which was four times that of the lower saltmarsh. Mangroves were evaluated as the optimal habitat for the pulmonates in terms of the environmental parameters moisture content and food availability. However, due to its longer inundation duration within each tidal cycle, use of the mangrove habitat by the pulmonates was impeded because of difficulties in oxygen acquisition under submerged conditions. Laboratory experiments revealed the oxygen intake of the pulmonates dropped abruptly to 4.3-9.0% of aerial rates when submerged. This result indicated that mangroves were not the optimal habitat for the pulmonates. Furthermore, the visiting frequency of predators (yellowfin bream Acanthopagrus australis and toadfishes, Tetraodontidae) was 1.3 times higher in the mangrove compared to those in the ecotone and upper saltmarsh habitats. Underwater video recording also suggested high mortality of these gastropods at 31.7-88.9% in mangrove and 0.80-0.98 times higher than that in saltmarsh, resulting from the predators preying in the mangrove habitat during high tides. Despite the abiotic factors facilitating the distribution of the pulmonates in the mangrove, the

Facilitating Quintuple helix innovation with urban living labs

OpenAIRE

Baccarne, Bastiaan; Schuurman, Dimitri; De Marez, Lieven

2015-01-01

This paper discusses the Urban Living Lab approach as a way to put the Quintuple Helix model for innovation into practice. In this analysis we focus on the concepts innovation democracy, ‘mode 3’ knowledge production, the innovation ecosystem as a system of societal subsystems and socioecological transition. The empirical analysis is performed by means of a multidimensional case study design, applied on a project-based ad hoc collaborative innovation development process in an ecological doma...

The type II collagen fragments Helix-II and CTX-II reveal different enzymatic pathways of human cartilage collagen degradation

DEFF Research Database (Denmark)

Charni-Ben Tabassi, N; Desmarais, S; Jensen, Anne-Christine Bay

2008-01-01

human recombinant cathepsins (Cats) and matrix-metalloproteases (MMPs). Next, we analyzed the spontaneous release of Helix-II and CTX-II from cartilage sections of patients with knee OA who were immediately deep frozen after joint replacement to preserve endogenous enzyme activity until assay. Cartilage....... Cat D was unable to digest intact cartilage. MMPs-1, -3, -7, -9, and -13 efficiently released CTX-II, but only small amount of Helix-II. Neither CTX-II nor Helix-II alone was able to reflect accurately the collagenolytic activity of Cats and MMPs as reflected by the release of hydroxyproline. In OA...

Helix Nebula and CERN: A Symbiotic approach to exploiting commercial clouds

CERN Document Server

Barreiro Megino, Fernando Harald; Kucharczyk, Katarzyna; Medrano Llamas, Ramón; van der Ster, Daniel

2014-01-01

The recent paradigm shift toward cloud computing in IT, and general interest in "Big Data" in particular, have demonstrated that the computing requirements of HEP are no longer globally unique. Indeed, the CERN IT department and LHC experiments have already made significant R&D investments in delivering and exploiting cloud computing resources. While a number of technical evaluations of interesting commercial offerings from global IT enterprises have been performed by various physics labs, further technical, security, sociological, and legal issues need to be address before their large-scale adoption by the research community can be envisaged. Helix Nebula - the Science Cloud is an initiative that explores these questions by joining the forces of three European research institutes (CERN, ESA and EMBL) with leading European commercial IT enterprises. The goals of Helix Nebula are to establish a cloud platform federating multiple commercial cloud providers, along with new business models, which can sustain ...

Helix Nebula and CERN: A Symbiotic approach to exploiting commercial clouds

CERN Multimedia

Barreiro Megino, Fernando Harald; Kucharczyk, Katarzyna; Medrano Llamas, Ramón; van der Ster, Daniel

2013-01-01

The recent paradigm shift toward cloud computing in IT, and general interest in "Big Data" in particular, have demonstrated that the computing requirements of HEP are no longer globally unique. Indeed, the CERN IT department and LHC experiments have already made significant R&D; investments in delivering and exploiting cloud computing resources. While a number of technical evaluations of interesting commercial offerings from global IT enterprises have been performed by various physics labs, further technical, security, sociological, and legal issues need to be address before their large-scale adoption by the research community can be envisaged. Helix Nebula - the Science Cloud is an initiative that explores these questions by joining the forces of three European research institutes (CERN, ESA and EMBL) with leading European commercial IT enterprises. The goals of Helix Nebula are to establish a cloud platform federating multiple commercial cloud providers, along with new business models, which can sustain...

Elevated endogenous expression of the dominant negative basic helix-loop-helix protein ID1 correlates with significant centrosome abnormalities in human tumor cells

Directory of Open Access Journals (Sweden)

Gutmann Anja

2010-01-01

Full Text Available Abstract Background ID proteins are dominant negative inhibitors of basic helix-loop-helix transcription factors that have multiple functions during development and cellular differentiation. Ectopic (over-expression of ID1 extends the lifespan of primary human epithelial cells. High expression levels of ID1 have been detected in multiple human malignancies, and in some have been correlated with unfavorable clinical prognosis. ID1 protein is localized at the centrosomes and forced (over-expression of ID1 results in errors during centrosome duplication. Results Here we analyzed the steady state expression levels of the four ID-proteins in 18 tumor cell lines and assessed the number of centrosome abnormalities. While expression of ID1, ID2, and ID3 was detected, we failed to detect protein expression of ID4. Expression of ID1 correlated with increased supernumerary centrosomes in most cell lines analyzed. Conclusions This is the first report that shows that not only ectopic expression in tissue culture but endogenous levels of ID1 modulate centrosome numbers. Thus, our findings support the hypothesis that ID1 interferes with centrosome homeostasis, most likely contributing to genomic instability and associated tumor aggressiveness.

Study on the contamination of transuranides in Pulmonata gastropoda collected in Palomares (Spain)

International Nuclear Information System (INIS)

Aragon, A.; Espinosa, A.; Anton, M.P.

2006-01-01

A study on the contamination levels and distribution of plutonium and americium in gastropods collected in Palomares (south-east Spain) was performed. This region is partially contaminated with actinides following the 1966 nuclear accident. The existence of plutonium and americium in gastropods (Helix albicans and Theba pisana), along with their great gastronomic interest in the area, reinforces the concern in studying the incorporation of these radioelements to a trophic level of the alimentary chain. In this work, plutonium concentration levels have been determined in the excrements, washing waters, flesh and shell of different types of gastropods collected in various sampling campaigns. Pretreatment of the snail samples for further transuranics analyses was based on culinary customs of the region. First, the gastropods had a biological rest, allowing the removal of the non-adsorbed or non-retained ingested material, and then the excrements were collected by washing the snails. Water with excrements was filtered using different filters and analyzed separately. Once rinsed, the snails were dipped into salty water to eliminate the slime, finally, after boiling, the soft tissue was separated from the shell. Plutonium and americium analyses have been carried out sequentially, following normalized procedures for the determination of these radionuclides. The results show the distribution of plutonium in washing and boiling water, excrements, soft tissues and shell of the snails. Autoradiographies performed to soft tissues made evident that the contamination was incorporated into the gastropods as radioactive particles. In addition, it has been estimated that the consumption of one kilogram of snails collected in the most contaminated area of Palomares could reach 1/3 of the effective dose (due to ingestion) to the inhabitants of the area. (author)

Helix Nebula and CERN: A Symbiotic approach to exploiting commercial clouds

Science.gov (United States)

Barreiro Megino, Fernando H.; Jones, Robert; Kucharczyk, Katarzyna; Medrano Llamas, Ramón; van der Ster, Daniel

2014-06-01

The recent paradigm shift toward cloud computing in IT, and general interest in "Big Data" in particular, have demonstrated that the computing requirements of HEP are no longer globally unique. Indeed, the CERN IT department and LHC experiments have already made significant R&D investments in delivering and exploiting cloud computing resources. While a number of technical evaluations of interesting commercial offerings from global IT enterprises have been performed by various physics labs, further technical, security, sociological, and legal issues need to be address before their large-scale adoption by the research community can be envisaged. Helix Nebula - the Science Cloud is an initiative that explores these questions by joining the forces of three European research institutes (CERN, ESA and EMBL) with leading European commercial IT enterprises. The goals of Helix Nebula are to establish a cloud platform federating multiple commercial cloud providers, along with new business models, which can sustain the cloud marketplace for years to come. This contribution will summarize the participation of CERN in Helix Nebula. We will explain CERN's flagship use-case and the model used to integrate several cloud providers with an LHC experiment's workload management system. During the first proof of concept, this project contributed over 40.000 CPU-days of Monte Carlo production throughput to the ATLAS experiment with marginal manpower required. CERN's experience, together with that of ESA and EMBL, is providing a great insight into the cloud computing industry and highlighted several challenges that are being tackled in order to ease the export of the scientific workloads to the cloud environments.

Contaminant exposure in terrestrial vertebrates

International Nuclear Information System (INIS)

Smith, Philip N.; Cobb, George P.; Godard-Codding, Celine; Hoff, Dale; McMurry, Scott T.; Rainwater, Thomas R.; Reynolds, Kevin D.

2007-01-01

Here we review mechanisms and factors influencing contaminant exposure among terrestrial vertebrate wildlife. There exists a complex mixture of biotic and abiotic factors that dictate potential for contaminant exposure among terrestrial and semi-terrestrial vertebrates. Chemical fate and transport in the environment determine contaminant bioaccessibility. Species-specific natural history characteristics and behavioral traits then play significant roles in the likelihood that exposure pathways, from source to receptor, are complete. Detailed knowledge of natural history traits of receptors considered in conjunction with the knowledge of contaminant behavior and distribution on a site are critical when assessing and quantifying exposure. We review limitations in our understanding of elements of exposure and the unique aspects of exposure associated with terrestrial and semi-terrestrial taxa. We provide insight on taxa-specific traits that contribute, or limit exposure to, transport phenomenon that influence exposure throughout terrestrial systems, novel contaminants, bioavailability, exposure data analysis, and uncertainty associated with exposure in wildlife risk assessments. Lastly, we identify areas related to exposure among terrestrial and semi-terrestrial organisms that warrant additional research. - Both biotic and abiotic factors determine chemical exposure for terrestrial vertebrates

A Circa-decadal Change in the Gastropod Fauna on a Tidal Flat in an Island Mangrove Estuary(Ecology)

OpenAIRE

Shun-ichi, Ohgaki; Takeharu, Kosuge; Ishigaki Tropical Station, Seikai National Fisheries Research Institute

2005-01-01

An investigation on gastropod fauna was carried out on a tidal flat in the Nagura Estuary on Ishigaki Island, the Ryukyu Islands in 1989 and 1998 using similar methods. 470-480 guadrats covering ca. 1900m^2 were surveyed during low tides from February to April in each year. Of the total 19 species recorded, the range of eight species had varied significantly between the two surveys, with six species expanding their range and two species contracting their range. Percentage in abundance of mudd...

The Impact of the ‘Austrian’ Mutation of the Amyloid Precursor Protein Transmembrane Helix is Communicated to the Hinge Region

DEFF Research Database (Denmark)

Stelzer, Walter; Scharnagl, Christina; Leurs, Ulrike

2016-01-01

The transmembrane helix of the amyloid precursor protein is subject to proteolytic cleavages by γ-secretase at different sites resulting in Aβ peptides of different length and toxicity. A number of point mutations within this transmembrane helix alter the cleavage pattern thus enhancing production...... destabilizes amide hydrogen bonds in the hinge which connects dimerization and cleavage regions. Weaker intrahelical hydrogen bonds at the hinge may enhance helix bending and thereby affect recognition of the transmembrane substrate by the enzyme and/or presentation of its cleavage sites to the catalytic cleft....

Rendezvous of the "Third Kind": Triple Helix Origins and Future Possibilities

Science.gov (United States)

Etzkowitz, Henry

2015-01-01

The Triple Helix, representing university-industry-government interactions, was rooted in a 1993 International Workshop on University-Industry Relations at UNAM's Centro Para la Innovacion Technologica in Mexico City. Impelled by Mexican reality, where university-industry interactions and the institutions themselves operated within a governmental…

Unpredictable responses of garden snail (Helix aspersa) populations to climate change

NARCIS (Netherlands)

Bezemer, T.M.; Knight, K.J.

2001-01-01

We studied the impact of climate change on the population dynamics of the garden snail (Helix aspersa) in the Ecotron controlled environment facility. The experimental series ran for three plant generations, allowing the snails to reproduce. We investigated the isolated and combined effects of

Use of 1–4 interaction scaling factors to control the conformational equilibrium between α-helix and β-strand

Energy Technology Data Exchange (ETDEWEB)

Pang, Yuan-Ping, E-mail: pang@mayo.edu

2015-02-06

Highlights: • 1–4 interaction scaling factors are used to adjust conformational energy. • This article reports the effects of these factors on protein conformations. • Reducing these factors changes a helix to a strand in molecular dynamics simulation. • Increasing these factors causes the reverse conformational change. • These factors control the conformational equilibrium between helix and strand. - Abstract: 1–4 interaction scaling factors are used in AMBER forcefields to reduce the exaggeration of short-range repulsion caused by the 6–12 Lennard-Jones potential and a nonpolarizable charge model and to obtain better agreements of small-molecule conformational energies with experimental data. However, the effects of these scaling factors on protein secondary structure conformations have not been investigated until now. This article reports the finding that the 1–4 interactions among the protein backbone atoms separated by three consecutive covalent bonds are more repulsive in the α-helix conformation than in two β-strand conformations. Therefore, the 1–4 interaction scaling factors of protein backbone torsions ϕ and ψ control the conformational equilibrium between α-helix and β-strand. Molecular dynamics simulations confirm that reducing the ϕ and ψ scaling factors readily converts the α-helix conformation of AcO-(AAQAA){sub 3}-NH{sub 2} to a β-strand conformation, and the reverse occurs when these scaling factors are increased. These results suggest that the ϕ and ψ scaling factors can be used to generate the α-helix or β-strand conformation in situ and to control the propensities of a forcefield for adopting secondary structure elements.

Chemical characterization of terrestrial gastropods of Brazilian mangroves by EDXRF; Caracterização química de gastrópodes terrestres de manguezais brasileiros por EDXRF

Energy Technology Data Exchange (ETDEWEB)

Mélo, Julyanne T.B.; Pereira Neto, Alberto; França, Elvis J. de, E-mail: julyanne.melo@ufpe.br, E-mail: nibbering4@gmail.com, E-mail: ejfranca@cnen.gov.br [Centro Regional de Ciências Nucleares (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Silva, Bruno F.; Melo, Ana M.M.A., E-mail: brunodasilva1996@hotmail.com, E-mail: amdemelo@hotmail.com [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil)

2017-07-01

In environmental studies, the application of multielement analytical techniques such as X-ray Fluorescence by Energy Dispersion - EDXRF is interesting due to the rapidity in the analysis and preservation of the sample. In the work, Fe, Mg, Mn, P, Sr and Zn were quantified in gastropods of the species Littoraria anguliferae Melampus coffea of mangroves located in tourist regions of Itamaracá, Pernambuco, and Barra de Guaratiba, Rio de Janeiro, Brazil. The samples were analyzed by EDXRF at a pressure lower than 30 Pa, detection time of 840 seconds in a Shimadzu EDX-720 model spectrometer. To guarantee the quality of the analytical procedure, reference materials SRM 2976 - Musseltissue and SRM 1547 - Peachleaves were analyzed. In both locations, the mass fractions of Mg and P were similar for L. anguliferae. For Zn, the average mass fraction of more than 3,000 mg kg{sup -1} of the Barra de Guaratiba animals was considerably higher than that obtained in the Itamaracá mangrove. The M. coffea species also presented a considerably higher accumulation of Zn (approximately 4500 mg kg{sup -1}) when compared to the mass fraction obtained in the Pernambuco mangrove. For Sr, there was a higher concentration in the Itamaracá mangrove (400mg kg{sup -1} for L. anguliferae 180 mg kg{sup -1} for M. coffea) compared to that obtained in Barra de Guaratiba. The analytical technique of EDXRF was successfully employed for the evaluation of both molluscan species as biomonitoring of the environmental quality of mangroves.

Genome-wide identification, classification, and functional analysis of the basic helix-loop-helix transcription factors in the cattle, Bos Taurus.

Science.gov (United States)

Li, Fengmei; Liu, Wuyi

2017-06-01

The basic helix-loop-helix (bHLH) transcription factors (TFs) form a huge superfamily and play crucial roles in many essential developmental, genetic, and physiological-biochemical processes of eukaryotes. In total, 109 putative bHLH TFs were identified and categorized successfully in the genomic databases of cattle, Bos Taurus, after removing redundant sequences and merging genetic isoforms. Through phylogenetic analyses, 105 proteins among these bHLH TFs were classified into 44 families with 46, 25, 14, 3, 13, and 4 members in the high-order groups A, B, C, D, E, and F, respectively. The remaining 4 bHLH proteins were sorted out as 'orphans.' Next, these 109 putative bHLH proteins identified were further characterized as significantly enriched in 524 significant Gene Ontology (GO) annotations (corrected P value ≤ 0.05) and 21 significantly enriched pathways (corrected P value ≤ 0.05) that had been mapped by the web server KOBAS 2.0. Furthermore, 95 bHLH proteins were further screened and analyzed together with two uncharacterized proteins in the STRING online database to reconstruct the protein-protein interaction network of cattle bHLH TFs. Ultimately, 89 bHLH proteins were fully mapped in a network with 67 biological process, 13 molecular functions, 5 KEGG pathways, 12 PFAM protein domains, and 25 INTERPRO classified protein domains and features. These results provide much useful information and a good reference for further functional investigations and updated researches on cattle bHLH TFs.

The N-terminal tail of hERG contains an amphipathic α-helix that regulates channel deactivation.

Directory of Open Access Journals (Sweden)

Chai Ann Ng

Full Text Available The cytoplasmic N-terminal domain of the human ether-a-go-go related gene (hERG K+ channel is critical for the slow deactivation kinetics of the channel. However, the mechanism(s by which the N-terminal domain regulates deactivation remains to be determined. Here we show that the solution NMR structure of the N-terminal 135 residues of hERG contains a previously described Per-Arnt-Sim (PAS domain (residues 26-135 as well as an amphipathic α-helix (residues 13-23 and an initial unstructured segment (residues 2-9. Deletion of residues 2-25, only the unstructured segment (residues 2-9 or replacement of the α-helix with a flexible linker all result in enhanced rates of deactivation. Thus, both the initial flexible segment and the α-helix are required but neither is sufficient to confer slow deactivation kinetics. Alanine scanning mutagenesis identified R5 and G6 in the initial flexible segment as critical for slow deactivation. Alanine mutants in the helical region had less dramatic phenotypes. We propose that the PAS domain is bound close to the central core of the channel and that the N-terminal α-helix ensures that the flexible tail is correctly orientated for interaction with the activation gating machinery to stabilize the open state of the channel.

Restrictions on TWT Helix Voltage Ripple for Acceptable Notch Filter Performance

Energy Technology Data Exchange (ETDEWEB)

Hyslop, B.

1984-12-01

An ac ripple on the helix voltage of the 1-2 GHz TWT's creates FM sidebands that cause amplitude and phase modulation of the microwave TWT output signal. A limit of 16 volts peak-to-peak is required for acceptable superconducting notch filter performance.

The role of vermetid gastropods in the development of the Florida Middle Ground, northeast Gulf of Mexico

Science.gov (United States)

Reich, Christopher D.; Poore, Richard Z.; Hickey, Todd D.

2013-01-01

The Florida Middle Ground is a complex of north to northwest trending ridges that lie approximately 180 km northwest of Tampa Bay, Florida. The irregular ridges appear on the otherwise gently sloping West Florida shelf and exhibit between 10-15 m of relief. Modern studies interpret the ridges as remnants of a Holocene coral-reef buildup that today provide a hard substrate for growth of a variety of benthic organisms including hydrocorals, scleractinians, alcyonarians, and algae. Recent rotary coring reveals that the core of the eastern ridge of the Florida Middle Ground complex consists of unconsolidated marine calcareous muddy sand that is capped by a boundstone composed primarily of the sessile vermetid gastropod Petaloconchus sp., and overlays a weathered, fossiliferous limestone. Accelerator Mass Spectrometry radiocarbon ages (uncalibrated) on the 3.6-m thick vermetid worm rock indicate that it developed during a sea-level stillstand in the early Holocene (8,225 ±30-8,910 ± 25 yr B.P.). Our observations suggest that the Florida Middle Ground is a remnant of a series of shore parallel bars that formed in the early Holocene and were capped by a 3.6-m thick unit of vermetid gastropods. During a rapid sea-level rise that began ~8,000 yr B.P. the vermetids growth ceased and the worm rock preserved the ridges structure. Diver observations document that the edges of the ridges are currently being eroded and undermined by biological activity and current action, leading to calving of large capstone blocks.

Glass-like dynamics of the strain-induced coil/helix transition on a permanent polymer network.

Science.gov (United States)

Ronsin, O; Caroli, C; Baumberger, T

2016-02-14

We study the stress response to a step strain of covalently bonded gelatin gels in the temperature range where triple helix reversible crosslink formation is prohibited. We observe slow stress relaxation towards a T-dependent finite asymptotic level. We show that this is assignable to the strain-induced coil → helix transition, previously evidenced by Courty et al. [Proc. Natl. Acad. Sci. U. S. A. 102, 13457 (2005)], of a fraction of the polymer strands. Relaxation proceeds, in a first stage, according to a stretched exponential dynamics, then crosses over to a terminal simple exponential decay. The respective characteristic times τK and τf exhibit an Arrhenius-like T-dependence with an associated energy E incompatibly larger than the activation barrier height for the isomerisation process which sets the clock for an elementary coil → helix transformation event. We tentatively assign this glass-like slowing down of the dynamics to the long-range couplings due to the mechanical noise generated by the local elementary events in this random elastic medium.

Structure of the membrane anchor of pestivirus glycoprotein E(rns, a long tilted amphipathic helix.

Directory of Open Access Journals (Sweden)

Daniel Aberle

2014-02-01

Full Text Available E(rns is an essential virion glycoprotein with RNase activity that suppresses host cellular innate immune responses upon being partially secreted from the infected cells. Its unusual C-terminus plays multiple roles, as the amphiphilic helix acts as a membrane anchor, as a signal peptidase cleavage site, and as a retention/secretion signal. We analyzed the structure and membrane binding properties of this sequence to gain a better understanding of the underlying mechanisms. CD spectroscopy in different setups, as well as Monte Carlo and molecular dynamics simulations confirmed the helical folding and showed that the helix is accommodated in the amphiphilic region of the lipid bilayer with a slight tilt rather than lying parallel to the surface. This model was confirmed by NMR analyses that also identified a central stretch of 15 residues within the helix that is fully shielded from the aqueous layer, which is C-terminally followed by a putative hairpin structure. These findings explain the strong membrane binding of the protein and provide clues to establishing the E(rns membrane contact, processing and secretion.

Structure of the membrane anchor of pestivirus glycoprotein E(rns), a long tilted amphipathic helix.

Science.gov (United States)

Aberle, Daniel; Muhle-Goll, Claudia; Bürck, Jochen; Wolf, Moritz; Reißer, Sabine; Luy, Burkhard; Wenzel, Wolfgang; Ulrich, Anne S; Meyers, Gregor

2014-02-01

E(rns) is an essential virion glycoprotein with RNase activity that suppresses host cellular innate immune responses upon being partially secreted from the infected cells. Its unusual C-terminus plays multiple roles, as the amphiphilic helix acts as a membrane anchor, as a signal peptidase cleavage site, and as a retention/secretion signal. We analyzed the structure and membrane binding properties of this sequence to gain a better understanding of the underlying mechanisms. CD spectroscopy in different setups, as well as Monte Carlo and molecular dynamics simulations confirmed the helical folding and showed that the helix is accommodated in the amphiphilic region of the lipid bilayer with a slight tilt rather than lying parallel to the surface. This model was confirmed by NMR analyses that also identified a central stretch of 15 residues within the helix that is fully shielded from the aqueous layer, which is C-terminally followed by a putative hairpin structure. These findings explain the strong membrane binding of the protein and provide clues to establishing the E(rns) membrane contact, processing and secretion.

Unfolding four-helix bundles

Science.gov (United States)

Gray, Harry B.; Winkler, Jay R.; Kozak, John J.

2011-03-01

A geometrical model has been developed to describe the early stages of unfolding of cytochromes c‧ and c-b562 . Calculations are based on a step-wise extension of the polypeptide chain subject to the constraint that the spatial relationship among the residues of each triplet is fixed by the native-state crystallographic data. The response of each protein to these structural perturbations allows the evolution of each of the four helices in these two proteins to be differentiated. It is found that the two external helices in c‧ unfold before its two internal helices, whereas exactly the opposite behaviour is demonstrated by c-b562 . Each of these cytochromes has an extended, internal, non-helical ('turning') region that initially lags behind the most labile helix but then, at a certain stage (identified for each cytochrome), unravels before any of the four helices present in the native structure. It is believed that these predictions will be useful in guiding future experimental studies on the unfolding of these two cytochromes.

Arctic Terrestrial Biodiversity Monitoring Plan

DEFF Research Database (Denmark)

Christensen, Tom; Payne, J.; Doyle, M.

The Conservation of Arctic Flora and Fauna (CAFF), the biodiversity working group of the Arctic Council, established the Circumpolar Biodiversity Monitoring Program (CBMP) to address the need for coordinated and standardized monitoring of Arctic environments. The CBMP includes an international...... on developing and implementing long-term plans for monitoring the integrity of Arctic biomes: terrestrial, marine, freshwater, and coastal (under development) environments. The CBMP Terrestrial Expert Monitoring Group (CBMP-TEMG) has developed the Arctic Terrestrial Biodiversity Monitoring Plan (CBMP......-Terrestrial Plan/the Plan) as the framework for coordinated, long-term Arctic terrestrial biodiversity monitoring. The goal of the CBMP-Terrestrial Plan is to improve the collective ability of Arctic traditional knowledge (TK) holders, northern communities, and scientists to detect, understand and report on long...

The Basic/Helix-Loop-Helix Protein Family in Gossypium: Reference Genes and Their Evolution during Tetraploidization.

Directory of Open Access Journals (Sweden)

Qian Yan

Full Text Available Basic/helix-loop-helix (bHLH proteins comprise one of the largest transcription factor families and play important roles in diverse cellular and molecular processes. Comprehensive analyses of the composition and evolution of the bHLH family in cotton are essential to elucidate their functions and the molecular basis of cotton development. By searching bHLH homologous genes in sequenced diploid cotton genomes (Gossypium raimondii and G. arboreum, a set of cotton bHLH reference genes containing 289 paralogs were identified and named as GobHLH001-289. Based on their phylogenetic relationships, these cotton bHLH proteins were clustered into 27 subfamilies. Compared to those in Arabidopsis and cacao, cotton bHLH proteins generally increased in number, but unevenly in different subfamilies. To further uncover evolutionary changes of bHLH genes during tetraploidization of cotton, all genes of S5a and S5b subfamilies in upland cotton and its diploid progenitors were cloned and compared, and their transcript profiles were determined in upland cotton. A total of 10 genes of S5a and S5b subfamilies (doubled from A- and D-genome progenitors maintained in tetraploid cottons. The major sequence changes in upland cotton included a 15-bp in-frame deletion in GhbHLH130D and a long terminal repeat retrotransposon inserted in GhbHLH062A, which eliminated GhbHLH062A expression in various tissues. The S5a and S5b bHLH genes of A and D genomes (except GobHLH062 showed similar transcription patterns in various tissues including roots, stems, leaves, petals, ovules, and fibers, while the A- and D-genome genes of GobHLH110 and GobHLH130 displayed clearly different transcript profiles during fiber development. In total, this study represented a genome-wide analysis of cotton bHLH family, and revealed significant changes in sequence and expression of these genes in tetraploid cottons, which paved the way for further functional analyses of bHLH genes in the cotton genus.

Helix Nebula and CERN: A Symbiotic approach to exploiting commercial clouds

International Nuclear Information System (INIS)

Megino, Fernando H Barreiro; Jones, Robert; Llamas, Ramón Medrano; Ster, Daniel van der; Kucharczyk, Katarzyna

2014-01-01

The recent paradigm shift toward cloud computing in IT, and general interest in 'Big Data' in particular, have demonstrated that the computing requirements of HEP are no longer globally unique. Indeed, the CERN IT department and LHC experiments have already made significant R and D investments in delivering and exploiting cloud computing resources. While a number of technical evaluations of interesting commercial offerings from global IT enterprises have been performed by various physics labs, further technical, security, sociological, and legal issues need to be address before their large-scale adoption by the research community can be envisaged. Helix Nebula – the Science Cloud is an initiative that explores these questions by joining the forces of three European research institutes (CERN, ESA and EMBL) with leading European commercial IT enterprises. The goals of Helix Nebula are to establish a cloud platform federating multiple commercial cloud providers, along with new business models, which can sustain the cloud marketplace for years to come. This contribution will summarize the participation of CERN in Helix Nebula. We will explain CERN's flagship use-case and the model used to integrate several cloud providers with an LHC experiment's workload management system. During the first proof of concept, this project contributed over 40.000 CPU-days of Monte Carlo production throughput to the ATLAS experiment with marginal manpower required. CERN's experience, together with that of ESA and EMBL, is providing a great insight into the cloud computing industry and highlighted several challenges that are being tackled in order to ease the export of the scientific workloads to the cloud environments.

Microplastics in the terrestrial ecosystem: Implications for Lumbricus terrestris (Oligochaeta, Lumbricidae)

NARCIS (Netherlands)

Huerta Lwanga, Esperanza; Gertsen, H.F.; Gooren, H.; Peters, P.D.; Salanki, T.E.; Ploeg, van der M.J.C.; Besseling, E.; Koelmans, A.A.; Geissen, V.

2016-01-01

Plastic debris is widespread in the environment, but information on the effects of microplastics on terrestrial fauna is completely lacking. Here, we studied the survival and fitness of the earthworm Lumbricus terrestris (Oligochaeta, Lumbricidae) exposed to microplastics (Polyethylene, <150 μm)

CFD analysis and flow model reduction for surfactant production in helix reactor

NARCIS (Netherlands)

Nikačević, N.M.; Thielen, L.; Twerda, A.; Hof, P.M.J. van den

2014-01-01

Flow pattern analysis in a spiral Helix reactor is conducted, for the application in the commercial surfactant production. Step change response curves (SCR) were obtained from numerical tracer experiments by three-dimensional computational fluid dynamics (CFD) simulations. Non-reactive flow is

Surface expression and subunit specific control of steady protein levels by the Kv7.2 helix A-B linker.

Directory of Open Access Journals (Sweden)

Paloma Aivar

Full Text Available Kv7.2 and Kv7.3 are the main components of the neuronal voltage-dependent M-current, which is a subthreshold potassium conductance that exerts an important control on neuronal excitability. Despite their predominantly intracellular distribution, these channels must reach the plasma membrane in order to control neuronal activity. Thus, we analyzed the amino acid sequence of Kv7.2 to identify intrinsic signals that may control its surface expression. Removal of the interlinker connecting helix A and helix B of the intracellular C-terminus produces a large increase in the number of functional channels at the plasma membrane. Moreover, elimination of this linker increased the steady-state amount of protein, which was not associated with a decrease of protein degradation. The magnitude of this increase was inversely correlated with the number of helix A - helix B linkers present in the tetrameric channel assemblies. In contrast to the remarkable effect on the amount of Kv7.2 protein, removal of the Kv7.2 linker had no detectable impact on the steady-state levels of Kv7.3 protein.

Helix-helix inversion of an optically-inactive π-conjugated foldamer triggered by concentration changes of a single enantiomeric guest leading to a change in the helical stability.

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Liu, Lijia; Ousaka, Naoki; Horie, Miki; Mamiya, Fumihiko; Yashima, Eiji

2016-09-27

A preferred-handed helicity induced in an optically-inactive poly(phenyleneethynylene)-based foldamer bearing carboxylic acid pendants upon complexation with a single enantiomeric diamine was subsequently inverted into the opposite helix upon further addition of the diamine, accompanied by a remarkable change in the stability of the helices.

Contact Stress Analysis for Gears of Different Helix Angle Using Finite Element Method

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Patil Santosh

2014-07-01

Full Text Available The gear contact stress problem has been a great point of interest for many years, but still an extensive research is required to understand the various parameters affecting this stress. Among such parameters, helix angle is one which has played a crucial role in variation of contact stress. Numerous studies have been carried out on spur gear for contact stress variation. Hence, the present work is an attempt to study the contact stresses among the helical gear pairs, under static conditions, by using a 3D finite element method. The helical gear pairs on which the analysis is carried are 0, 5, 15, 25 degree helical gear sets. The Lagrange multiplier algorithm has been used between the contacting pairs to determine the stresses. The helical gear contact stress is evaluated using FE model and results have also been found at different coefficient of friction, varying from 0.0 to 0.3. The FE results have been further compared with the analytical calculations. The analytical calculations are based upon Hertz and AGMA equations, which are modified to include helix angle. The commercial finite element software was used in the study and it was shown that this approach can be applied to gear design efficiently. The contact stress results have shown a decreasing trend, with increase in helix angle.

Freshwater gastropods diversity hotspots: three new species from the Uruguay River (South America

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Diego E. Gutiérrez Gregoric

2016-06-01

Full Text Available Background: The Atlantic Forest is globally one of the priority ecoregions for biodiversity conservation. In Argentina, it is represented by the Paranense Forest, which covers a vast area of Misiones Province between the Paraná and Uruguay rivers. The Uruguay River is a global hotspot of freshwater gastropod diversity, here mainly represented by Tateidae (genus Potamolithus and to a lesser extent Chilinidae. The family Chilinidae (Gastropoda, Hygrophila includes 21 species currently recorded in Argentina, and three species in the Uruguay River. The species of Chilinidae occur in quite different types of habitats, but generally in clean oxygenated water recording variable temperature ranges. Highly oxygenated freshwater environments (waterfalls and rapids are the most vulnerable continental environments. We provide here novel information on three new species of Chilinidae from environments containing waterfalls and rapids in the Uruguay River malacological province of Argentina. Materials and Methods: The specimens were collected in 2010. We analyzed shell, radula, and nervous and reproductive systems, and determined the molecular genetics. The genetic distance was calculated for two mitochondrial markers (cytochrome c oxidase subunit I–COI- and cytochrome b -Cyt b- for these three new species and the species recorded from the Misionerean, Uruguay River and Lower Paraná-Río de la Plata malacological provinces. In addition, the COI data were analyzed phylogenetically by the neighbor-joining and Bayesian inference techniques. Results: The species described here are different in terms of shell, radula and nervous and reproductive systems, mostly based on the sculpture of the penis sheath. Phylogenetic analyses grouped the three new species with those present in the Lower Paraná-Río de la Plata and Uruguay River malacological provinces. Discussion: Phylogenetic analyses confirm the separation between the Uruguay River and the Misionerean

Bacterial morphogenesis and the enigmatic MreB helix.

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Errington, Jeff

2015-04-01

Work over the past decade has highlighted the pivotal role of the actin-like MreB family of proteins in the determination and maintenance of rod cell shape in bacteria. Early images of MreB localization revealed long helical filaments, which were suggestive of a direct role in governing cell wall architecture. However, several more recent, higher-resolution studies have questioned the existence or importance of the helical structures. In this Opinion article, I navigate a path through these conflicting reports, revive the helix model and summarize the key questions that remain to be answered.

Microplastics in the Terrestrial Ecosystem: Implications for Lumbricus terrestris (Oligochaeta, Lumbricidae).

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Huerta Lwanga, Esperanza; Gertsen, Hennie; Gooren, Harm; Peters, Piet; Salánki, Tamás; van der Ploeg, Martine; Besseling, Ellen; Koelmans, Albert A; Geissen, Violette

2016-03-01

Plastic debris is widespread in the environment, but information on the effects of microplastics on terrestrial fauna is completely lacking. Here, we studied the survival and fitness of the earthworm Lumbricus terrestris (Oligochaeta, Lumbricidae) exposed to microplastics (Polyethylene, digestion of ingested organic matter, microplastic was concentrated in cast, especially at the lowest dose (i.e., 7% in litter) because that dose had the highest proportion of digestible organic matter. Whereas 50 percent of the microplastics had a size of earthworms. These concentration-transport and size-selection mechanisms may have important implications for fate and risk of microplastic in terrestrial ecosystems.

Mechanical evaluation of quad-helix appliance made of low-nickel stainless steel wire.

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dos Santos, Rogério Lacerda; Pithon, Matheus Melo

2013-01-01

The objective of this study was to test the hypothesis that there is no difference between stainless steel and low-nickel stainless steel wires as regards mechanical behavior. Force, resilience, and elastic modulus produced by Quad-helix appliances made of 0.032-inch and 0.036-inch wires were evaluated. Sixty Quad-helix appliances were made, thirty for each type of alloy, being fifteen for each wire thickness, 0.032-in and 0.036-in. All the archwires were submitted to mechanical compression test using an EMIC DL-10000 machine simulating activations of 4, 6, 9, and 12 mm. Analysis of variance (ANOVA) with multiple comparisons and Tukey's test were used (p nickel stainless steel alloy had force, resilience, and elastic modulus similar to those made of stainless steel alloy.

Ecosystem Alterations and Species Range Shifts: An Atlantic-Mediterranean Cephalaspidean Gastropod in an Inland Egyptian Lake

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Malaquias, Manuel António E.

2016-01-01

The eastern Atlantic and Mediterranean marine Cephalaspidea gastropod Haminoea orbignyana was collected from Lake Qarun (Fayoum, Egypt), a landlocked lake that has undergone a shift from freshwater to estuarine conditions in the past 100 years. Species identity was confirmed by both morphological (anatomical dissection and scanning electron microscopy) and molecular methods (COI gene phylogeny). Observations suggested a robust population of H. orbignyana in the lake with a density of ca. 64 individuals/m2 and ca. 105 egg masses/m2 during surveys conducted in the summer of 2013. The vast majority of snails and egg masses were found under rocks. Observations of egg masses in the lab showed a gradual change from whitish to yellow-green as the eggs matured and the release of veliger larvae alone after about a week. Although adult cephalaspideans readily consumed filamentous red and green algae, and cyanobacteria, laboratory trials showed that they consumed significantly more of the red alga Ceramium sp., than of the green alga Cladophora glomerata, with consumption of Oscillatoria margaritifera being similar to those on the two algae. When grown on these resources for 16 days, H. orbignyana maintained their mass on the rhodophyte and cyanobacterium, but not in starvation controls. No cephalaspideans grew over the course of this experiment. Lake Qarun has been periodically restocked with Mediterranean fishes and prawns since the 1920s to maintain local fisheries, which represents a possible route of colonization for H. orbignyana. Yet, based on literature records, it seems more likely that invasion of the lake by this gastropod species has occurred only within the last 20 years. As human activities redistribute species through direct and indirect means, the structure of the community of this inland lake has become unpredictable and the long-term effects of these recent introductions are unknown. PMID:27248835

Ecosystem Alterations and Species Range Shifts: An Atlantic-Mediterranean Cephalaspidean Gastropod in an Inland Egyptian Lake.

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Edwin Cruz-Rivera

Full Text Available The eastern Atlantic and Mediterranean marine Cephalaspidea gastropod Haminoea orbignyana was collected from Lake Qarun (Fayoum, Egypt, a landlocked lake that has undergone a shift from freshwater to estuarine conditions in the past 100 years. Species identity was confirmed by both morphological (anatomical dissection and scanning electron microscopy and molecular methods (COI gene phylogeny. Observations suggested a robust population of H. orbignyana in the lake with a density of ca. 64 individuals/m2 and ca. 105 egg masses/m2 during surveys conducted in the summer of 2013. The vast majority of snails and egg masses were found under rocks. Observations of egg masses in the lab showed a gradual change from whitish to yellow-green as the eggs matured and the release of veliger larvae alone after about a week. Although adult cephalaspideans readily consumed filamentous red and green algae, and cyanobacteria, laboratory trials showed that they consumed significantly more of the red alga Ceramium sp., than of the green alga Cladophora glomerata, with consumption of Oscillatoria margaritifera being similar to those on the two algae. When grown on these resources for 16 days, H. orbignyana maintained their mass on the rhodophyte and cyanobacterium, but not in starvation controls. No cephalaspideans grew over the course of this experiment. Lake Qarun has been periodically restocked with Mediterranean fishes and prawns since the 1920s to maintain local fisheries, which represents a possible route of colonization for H. orbignyana. Yet, based on literature records, it seems more likely that invasion of the lake by this gastropod species has occurred only within the last 20 years. As human activities redistribute species through direct and indirect means, the structure of the community of this inland lake has become unpredictable and the long-term effects of these recent introductions are unknown.

The Penta Helix Model of Innovation in Oman: An HEI Perspective

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Alrence S Halibas

2017-05-01

Full Text Available Aim/Purpose: Countries today strategically pursue regional development and economic diversification to compete in the world market. Higher Education Institutions (HEIs are at the crux of this political strategy. The paper reviews how HEIs can propel regional socio-economic growth and development by way of research innovation and entrepreneurship. Background: Offering an academic perspective about the role of HEIs using the Penta Helix innovation network for business and social innovation, the paper discusses opportunities and challenges in gestating an innovation culture. It likewise seeks, identifies and details strategies and workable programs. Methodology: Best-practice innovation campaigns initiated by Omani HEIs in collaboration with capstone programs organized by the government were parsed from selected local and international literature. The study includes a causal analysis of innovation information contained in 40 out of 44 published OAAA Quality Audit reports about HEIs from 2009 to 2016. The best-practice programs serve as success indicators and will be used as a field metric effect a Penta Helix blueprint for innovation. Contribution: The paper discusses how HEIs can engender, nurture, drive, and sustain innovation and entrepreneurial activity by using an innovation strategic blueprint like the Penta Helix model. It gathers together the recent historical attempts at promoting innovation by HEIs. It likewise suggests the creation of a network channel to allow key players in the innovation network to share innovation information and to collaborate with each other. Furthermore, it contributes to the development of innovation culture in HEIs. Findings: Expectations run high in academia. For one, universities believe that all innovations embryonically begin within their halls. Universities–too–believe it is naturally incumbent on them to stimulate and advance innovation despite that most innovation programs are initiated by the

Lead reduces shell mass in juvenile garden snails (Helix aspersa)

International Nuclear Information System (INIS)

Beeby, Alan; Richmond, Larry; Herpe, Florian

2002-01-01

A high Pb diet causes differential depression of juvenile shell mass in populations of Helix. - In an earlier paper examining inherited tolerance to Pb, the shell growth of laboratory-bred offspring of Helix aspersa from contaminated sites was compared with that of juveniles from naieve populations on dosed and undosed diets. Eight-week-old snails were fed either 500 μg g -1 Pb or a control food in competitive trials between two populations. In the first series of trials, a parental history of exposure to Pb did not confer any advantage to either of two populations (BI and MI) competing with a naieve population (LE), whether Pb was present in the diet or not. However, in the analysis of their metal concentrations reported here, LE are found to retain higher levels of Pb in the soft tissues than either BI or MI. Compared to their siblings on the unleaded diet, dosed LE and BI juveniles had lower soft tissue concentrations of Ca and Mg. Although the growth in shell height is unaffected by diet, LE and BI juveniles build lighter shells on the Pb-dosed diet, achieving around 75% of the shell mass of their controls. In contrast, the shell weights of dosed MI juveniles are depressed by only 15% and show no change in the essential metal concentrations of their soft tissues. A second experiment using five populations fed only the dosed food show that the shell weight/soft tissue weight ratios are comparable to the dosed snails of the previous experiment. Building a lighter shell thus appears to be the common response of all Helix populations to a high Pb diet, at least amongst juveniles. The reduction in its mass means that less Ca and Mg is added to the shell and, along with the lowered soft tissue concentrations observed in some populations, may be a consequence of an increased effort to excrete Pb. The possibility that the MI population shows a genotypic adaptation, perhaps as some form of modification of its Ca metabolism, is briefly discussed

V. Terrestrial vertebrates

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Dean Pearson; Deborah Finch

2011-01-01

Within the Interior West, terrestrial vertebrates do not represent a large number of invasive species relative to invasive weeds, aquatic vertebrates, and invertebrates. However, several invasive terrestrial vertebrate species do cause substantial economic and ecological damage in the U.S. and in this region (Pimental 2000, 2007; Bergman and others 2002; Finch and...

Antimicrobial Effects of Helix D-derived Peptides of Human Antithrombin III*

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Papareddy, Praveen; Kalle, Martina; Bhongir, Ravi K. V.; Mörgelin, Matthias; Malmsten, Martin; Schmidtchen, Artur

2014-01-01

Antithrombin III (ATIII) is a key antiproteinase involved in blood coagulation. Previous investigations have shown that ATIII is degraded by Staphylococcus aureus V8 protease, leading to release of heparin binding fragments derived from its D helix. As heparin binding and antimicrobial activity of peptides frequently overlap, we here set out to explore possible antibacterial effects of intact and degraded ATIII. In contrast to intact ATIII, the results showed that extensive degradation of the molecule yielded fragments with antimicrobial activity. Correspondingly, the heparin-binding, helix d-derived, peptide FFFAKLNCRLYRKANKSSKLV (FFF21) of human ATIII, was found to be antimicrobial against particularly the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa. Fluorescence microscopy and electron microscopy studies demonstrated that FFF21 binds to and permeabilizes bacterial membranes. Analogously, FFF21 was found to induce membrane leakage of model anionic liposomes. In vivo, FFF21 significantly reduced P. aeruginosa infection in mice. Additionally, FFF21 displayed anti-endotoxic effects in vitro. Taken together, our results suggest novel roles for ATIII-derived peptide fragments in host defense. PMID:25202017

The gastropod-symbiotic sea anemone genus Isosicyonis Carlgren, 1927 (Actiniaria: Actiniidae: a new species from the Weddell Sea (Antarctica that clarifies the taxonomic position of the genus

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Estefanía Rodríguez

2008-03-01

Full Text Available A second species of the sea anemone genus Isosicyonis is described and illustrated from 16 specimens collected in the Weddell Sea (Antarctica on the Polarstern cruises ANT XVII/3, ANT XXI/2 and ANT XXIII/8. Isosicyonis striata n. sp. is easily distinguishable externally from the other species of the genus Isosicyonis alba by its pattern: white longitudinal stripes on the column, oral disc, and tentacles. It is also distinguished by internal features including the retractor muscles, parietobasilar muscles, marginal sphincter muscles, number of mesenteries, and cnidae. The genus Isosycionis is currently only known from the Southern Ocean. Both species of Isosicyonis live in association with a gastropod, with a single sea anemone occupying almost the whole shell of its gastropod host. The description of this new species, and our re-examination of Isosicyonis alba, resolves the controversial higher taxonomic position of the genus, confirming its placement within the Endomyaria.

Evidence for a central role of PrP helix 2 in the nucleation of amyloid fibrils.

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Honda, Ryo; Kuwata, Kazuo

2018-02-01

Amyloid fibrils are filamentous protein aggregates associated with the pathogenesis of a wide variety of human diseases. The formation of such aggregates typically follows nucleation-dependent kinetics, wherein the assembly and structural conversion of amyloidogenic proteins into oligomeric aggregates (nuclei) is the rate-limiting step of the overall reaction. In this study, we sought to gain structural insights into the oligomeric nuclei of the human prion protein (PrP) by preparing a series of deletion mutants lacking 14-44 of the C-terminal 107 residues of PrP and examined the kinetics and thermodynamics of these mutants in amyloid formation. An analysis of the experimental data using the concepts of the Φ-value analysis indicated that the helix 2 region (residues 168-196) acquires an amyloid-like β-sheet during nucleation, whereas the other regions preserves a relatively disordered structure in the nuclei. This finding suggests that the helix 2 region serves as the nucleation site for the assembly of amyloid fibrils.-Honda, R., Kuwata, K. Evidence for a central role of PrP helix 2 in the nucleation of amyloid fibrils.

Human telomeric DNA: G-quadruplex, i-motif and Watson–Crick double helix

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Phan, Anh Tuân; Mergny, Jean-Louis

2002-01-01

Human telomeric DNA composed of (TTAGGG/CCCTAA)n repeats may form a classical Watson–Crick double helix. Each individual strand is also prone to quadruplex formation: the G-rich strand may adopt a G-quadruplex conformation involving G-quartets whereas the C-rich strand may fold into an i-motif based on intercalated C·C+ base pairs. Using an equimolar mixture of the telomeric oligonucleotides d[AGGG(TTAGGG)3] and d[(CCCTAA)3CCCT], we defined which structures existed and which would be the predominant species under a variety of experimental conditions. Under near-physiological conditions of pH, temperature and salt concentration, telomeric DNA was predominantly in a double-helix form. However, at lower pH values or higher temperatures, the G-quadruplex and/or the i-motif efficiently competed with the duplex. We also present kinetic and thermodynamic data for duplex association and for G-quadruplex/i-motif unfolding. PMID:12409451

Academic Spin-off as Triple Helix Element: Case-Study of Russian Regions

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Konstantin Ivanovich Grasmik

2016-10-01

Full Text Available The innovation process is becoming more open. According to the concept of the Triple Helix, this requires the creation of institutions capable of mediating the interaction of agents, primarily related to the different elements of the innovation system. The academic spin-off is not only a form of technology transfer, set up at the university but also the institution that provides the interaction of scientists and entrepreneurs. This article gives an analysis of the implementation of the program of creating academic spin-offs in Russia. The main focus of the study is to analyze the affiliation of university spin-off with other companies, including personal links of founders. Research reveals that linkages are substantially personal: University staff member at the same time could be an entrepreneur. This finding allows not only clarifying the concept of the Triple Helix but also increasing the effectiveness of innovation policy, focusing on employees who can combine science and entrepreneurship.

Salt bridge interactions within the β2 integrin α7 helix mediate force-induced binding and shear resistance ability.

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Zhang, Xiao; Li, Linda; Li, Ning; Shu, Xinyu; Zhou, Lüwen; Lü, Shouqin; Chen, Shenbao; Mao, Debin; Long, Mian

2018-01-01

The functional performance of the αI domain α 7 helix in β 2 integrin activation depends on the allostery of the α 7 helix, which axially slides down; therefore, it is critical to elucidate what factors regulate the allostery. In this study, we determined that there were two conservative salt bridge interaction pairs that constrain both the upper and bottom ends of the α 7 helix. Molecular dynamics (MD) simulations for three β 2 integrin members, lymphocyte function-associated antigen-1 (LFA-1; α L β 2 ), macrophage-1 antigen (Mac-1; α M β 2 ) and α x β 2 , indicated that the magnitude of the salt bridge interaction is related to the stability of the αI domain and the strength of the corresponding force-induced allostery. The disruption of the salt bridge interaction, especially with double mutations in both salt bridges, significantly reduced the force-induced allostery time for all three members. The effects of salt bridge interactions of the αI domain α 7 helix on β 2 integrin conformational stability and allostery were experimentally validated using Mac-1 constructs. The results demonstrated that salt bridge mutations did not alter the conformational state of Mac-1, but they did increase the force-induced ligand binding and shear resistance ability, which was consistent with MD simulations. This study offers new insight into the importance of salt bridge interaction constraints of the αI domain α 7 helix and external force for β 2 integrin function. © 2017 Federation of European Biochemical Societies.

The Helix Nebula Viewed in HCO+: Large-scale Mapping of the J = 1 → 0 Transition

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Zeigler, N. R.; Zack, L. N.; Woolf, N. J.; Ziurys, L. M.

2013-11-01

The J = 1 → 0 transition of HCO+ at 89 GHz has been mapped across the Helix Nebula (NGC 7293) with 70'' spatial resolution (1.68 km s-1 velocity resolution) using the Arizona Radio Observatory 12 m telescope. This work is the first large-scale mapping project of a dense gas tracer (n(H2) ~ 105 cm-3) in old planetary nebulae. Observations of over 200 positions encompassing the classical optical image were conducted with a 3σ noise level of ~20 mK. HCO+ was detected at most positions, often exhibiting multiple velocity components indicative of complex kinematic structures in dense gas. The HCO+ spectra suggest that the Helix is composed of a bipolar, barrel-like structure with red- and blue-shifted halves, symmetric with respect to the central star and oriented ~10° east from the line of sight. A second bipolar, higher velocity outflow exists as well, situated along the direction of the Helix "plumes." The column density of HCO+ across the Helix is N tot ~ 1.5 × 1010-5.0 × 1011 cm-2, with an average value N ave ~ 1 × 1011 cm-2, corresponding to an abundance, relative to H2, of f ~ 1.4 × 10-8. This value is similar to that observed in young PN, and contradicts chemical models, which predict that the abundance of HCO+ decreases with nebular age. This study indicates that polyatomic molecules readily survive the ultraviolet field of the central white dwarf, and can be useful in tracing nebular morphology in the very late stages of stellar evolution.

The cone snails of Cape Verde: Marine endemism at a terrestrial scale

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Howard Peters

2016-07-01

Full Text Available Cape Verde in the Eastern Atlantic is typical of many island groups in supporting a wealth of endemic species both terrestrial and marine. Marine gastropod molluscs of the genus Conus, commonly known as cone snails, occur in coastal tropical waters throughout the globe, but in Cape Verde their endemism reaches its apogee with 53 out of 56 species occurring nowhere else, the majority of which are restricted to single islands and frequently to single bays. However, Cape Verde is rapidly moving to a tourism-based economy with a projected boom in infrastructure development often coincidental with the shallow-water habitat of many range-restricted Conus. The conservation assessment of Conus to standards of the International Union for the Conservation of Nature (IUCN Red List of Endangered Species, found that 45.3% of 53 species assessed from Cape Verde are threatened or near-threatened with extinction compared to 7.4% of 579 species in the rest of the world. The only three Conus species globally assessed as Critically Endangered and on the cusp of extinction are all endemic to Cape Verde. Our analysis of Conus species distribution, together with spatial data of coastal protected areas and tourism development zones, identify important areas for future research and new marine protection. Our findings show that endemism with its associated risks for Conus in Cape Verde has worldwide parallels with many non-marine taxa, while our proposed strategy for Conus conservation extends beyond the confines of the country and this taxonomic group.

A conserved phenylalanine as a relay between the α5 helix and the GDP binding region of heterotrimeric Gi protein α subunit.

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Kaya, Ali I; Lokits, Alyssa D; Gilbert, James A; Iverson, Tina M; Meiler, Jens; Hamm, Heidi E

2014-08-29

G protein activation by G protein-coupled receptors is one of the critical steps for many cellular signal transduction pathways. Previously, we and other groups reported that the α5 helix in the G protein α subunit plays a major role during this activation process. However, the precise signaling pathway between the α5 helix and the guanosine diphosphate (GDP) binding pocket remains elusive. Here, using structural, biochemical, and computational techniques, we probed different residues around the α5 helix for their role in signaling. Our data showed that perturbing the Phe-336 residue disturbs hydrophobic interactions with the β2-β3 strands and α1 helix, leading to high basal nucleotide exchange. However, mutations in β strands β5 and β6 do not perturb G protein activation. We have highlighted critical residues that leverage Phe-336 as a relay. Conformational changes are transmitted starting from Phe-336 via β2-β3/α1 to Switch I and the phosphate binding loop, decreasing the stability of the GDP binding pocket and triggering nucleotide release. When the α1 and α5 helices were cross-linked, inhibiting the receptor-mediated displacement of the C-terminal α5 helix, mutation of Phe-336 still leads to high basal exchange rates. This suggests that unlike receptor-mediated activation, helix 5 rotation and translocation are not necessary for GDP release from the α subunit. Rather, destabilization of the backdoor region of the Gα subunit is sufficient for triggering the activation process. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Involvement of Na,K-pump in SEPYLRFamide-mediated reduction of cholinosensitivity in Helix neurons.

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Pivovarov, Arkady S; Foreman, Richard C; Walker, Robert J

2007-02-01

SEPYLRFamide acts as an inhibitory modulator of acetylcholine (ACh) receptors in Helix lucorum neurones. Ouabain, a specific inhibitor of Na,K-pump, (0.1 mM, bath application) decreased the ACh-induced inward current (ACh-current) and increased the leak current. Ouabain decreased the modulatory SEPYLRFamide effect on the ACh-current. There was a correlation between the effects of ouabain on the amplitude of the ACh-current and on the modulatory peptide effect. Ouabain and SEPYLRFamide inhibited the activity of Helix aspersa brain Na,K-ATPase. Activation of Na,K-pump by intracellular injection of 3 M Na acetate or 3 M NaCl reduced the modulatory peptide effect on the ACh-current. An inhibitor of Na/Ca-exchange, benzamil (25 muM, bath application), and an inhibitor of Ca(2+)-pump in the endoplasmic reticulum, thapsigargin (TG, applied intracellularly), both prevented the effect of ouabain on SEPYLRFamide-mediated modulatory effect. Another inhibitor of Ca(2+)-pump in the endoplasmic reticulum, cyclopiazonic acid (applied intracellularly), did not prevent the effect of ouabain on SEPYLRFamide-mediated modulatory effect. These results indicate that Na,K-pump is responsible for the SEPYLRFamide-mediated inhibition of ACh receptors in Helix neurons. Na/Ca-exchange and intracellular Ca(2+) released from internal pools containing TG-sensitive Ca(2+)-pump are involved in the Na,K-pump pathway for the SEPYLRFamide-mediated inhibition of ACh receptors.

Thermodynamic effects of replacements of Pro residues in helix interiors of maltose-binding protein.

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Prajapati, R S; Lingaraju, G M; Bacchawat, Kiran; Surolia, Avadhesha; Varadarajan, Raghavan

2003-12-01

Introduction of Pro residues into helix interiors results in protein destabilization. It is currently unclear if the converse substitution (i.e., replacement of Pro residues that naturally occur in helix interiors would be stabilizing). Maltose-binding protein is a large 370-amino acid protein that contains 21 Pro residues. Of these, three nonconserved residues (P48, P133, and P159) occur at helix interiors. Each of the residues was replaced with Ala and Ser. Stabilities were characterized by differential scanning calorimetry (DSC) as a function of pH and by isothermal urea denaturation studies as a function of temperature. The P48S and P48A mutants were found to be marginally more stable than the wild-type protein. In the pH range of 5-9, there is an average increase in T(m) values of P48A and P48S of 0.4 degrees C and 0.2 degrees C, respectively, relative to the wild-type protein. The other mutants are less stable than the wild type. Analysis of the effects of such Pro substitutions in MBP and in three other proteins studied to date suggests that substitutions are more likely to be stabilizing if the carbonyl group i-3 or i-4 to the mutation site is not hydrogen bonded in the wild-type protein. Copyright 2003 Wiley-Liss, Inc.

Praevalensen afhud- og slimhindesymptomer blandt gartnere der omgås Ficus benjamina (stuebirk) og Hedera helix (vedbend). Et tvaersnitsstudie

DEFF Research Database (Denmark)

Jørs, Erik

2003-01-01

Allergic and toxic initiative symptoms from skin, eyes and respiratory tract are well known among gardeners This study reports the prevalence of these symptoms among gardeners working with Ficus Benjamina (Fb) and Hedera helix (Hh).......Allergic and toxic initiative symptoms from skin, eyes and respiratory tract are well known among gardeners This study reports the prevalence of these symptoms among gardeners working with Ficus Benjamina (Fb) and Hedera helix (Hh)....

Terrestrial Analogs to Mars

Science.gov (United States)

Farr, T. G.; Arcone, S.; Arvidson, R. W.; Baker, V.; Barlow, N. G.; Beaty, D.; Bell, M. S.; Blankenship, D. D.; Bridges, N.; Briggs, G.; Bulmer, M.; Carsey, F.; Clifford, S. M.; Craddock, R. A.; Dickerson, P. W.; Duxbury, N.; Galford, G. L.; Garvin, J.; Grant, J.; Green, J. R.; Gregg, T. K. P.; Guinness, E.; Hansen, V. L.; Hecht, M. H.; Holt, J.; Howard, A.; Keszthelyi, L. P.; Lee, P.; Lanagan, P. D.; Lentz, R. C. F.; Leverington, D. W.; Marinangeli, L.; Moersch, J. E.; Morris-Smith, P. A.; Mouginis-Mark, P.; Olhoeft, G. R.; Ori, G. G.; Paillou, P.; Reilly, J. F., II; Rice, J. W., Jr.; Robinson, C. A.; Sheridan, M.; Snook, K.; Thomson, B. J.; Watson, K.; Williams, K.; Yoshikawa, K.

2002-08-01

It is well recognized that interpretations of Mars must begin with the Earth as a reference. The most successful comparisons have focused on understanding geologic processes on the Earth well enough to extrapolate to Mars' environment. Several facets of terrestrial analog studies have been pursued and are continuing. These studies include field workshops, characterization of terrestrial analog sites, instrument tests, laboratory measurements (including analysis of Martian meteorites), and computer and laboratory modeling. The combination of all these activities allows scientists to constrain the processes operating in specific terrestrial environments and extrapolate how similar processes could affect Mars. The Terrestrial Analogs for Mars Community Panel has considered the following two key questions: (1) How do terrestrial analog studies tie in to the Mars Exploration Payload Assessment Group science questions about life, past climate, and geologic evolution of Mars, and (2) How can future instrumentation be used to address these questions. The panel has considered the issues of data collection, value of field workshops, data archiving, laboratory measurements and modeling, human exploration issues, association with other areas of solar system exploration, and education and public outreach activities.

High-resolution orientation and depth of insertion of the voltage-sensing S4 helix of a potassium channel in lipid bilayers.

Science.gov (United States)

Doherty, Tim; Su, Yongchao; Hong, Mei

2010-08-27

The opening and closing of voltage-gated potassium (Kv) channels are controlled by several conserved Arg residues in the S4 helix of the voltage-sensing domain. The interaction of these positively charged Arg residues with the lipid membrane has been of intense interest for understanding how membrane proteins fold to allow charged residues to insert into lipid bilayers against free-energy barriers. Using solid-state NMR, we have now determined the orientation and insertion depth of the S4 peptide of the KvAP channel in lipid bilayers. Two-dimensional (15)N correlation experiments of macroscopically oriented S4 peptide in phospholipid bilayers revealed a tilt angle of 40 degrees and two possible rotation angles differing by 180 degrees around the helix axis. Remarkably, the tilt angle and one of the two rotation angles are identical to those of the S4 helix in the intact voltage-sensing domain, suggesting that interactions between the S4 segment and other helices of the voltage-sensing domain are not essential for the membrane topology of the S4 helix. (13)C-(31)P distances between the S4 backbone and the lipid (31)P indicate a approximately 9 A local thinning and 2 A average thinning of the DMPC (1,2-dimyristoyl-sn-glycero-3-phosphochloline)/DMPG (1,2-dimyristoyl-sn-glycero-3-phosphatidylglycerol) bilayer, consistent with neutron diffraction data. Moreover, a short distance of 4.6 A from the guanidinium C(zeta) of the second Arg to (31)P indicates the existence of guanidinium phosphate hydrogen bonding and salt bridges. These data suggest that the structure of the Kv gating helix is mainly determined by protein-lipid interactions instead of interhelical protein-protein interactions, and the S4 amino acid sequence encodes sufficient information for the membrane topology of this crucial gating helix. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Forced evolution of a regulatory RNA helix in the HIV-1 genome

NARCIS (Netherlands)

Berkhout, B.; Klaver, B.; Das, A. T.

1997-01-01

The 5'and 3'end of the HIV-1 RNA genome forms a repeat (R) element that encodes a double stem-loop structure (the TAR and polyA hairpins). Phylogenetic analysis of the polyA hairpin in different human and simian immunodeficiency viruses suggests that the thermodynamic stability of the helix is

Antimicrobial effects of helix D-derived peptides of human antithrombin III.

Science.gov (United States)

Papareddy, Praveen; Kalle, Martina; Bhongir, Ravi K V; Mörgelin, Matthias; Malmsten, Martin; Schmidtchen, Artur

2014-10-24

Antithrombin III (ATIII) is a key antiproteinase involved in blood coagulation. Previous investigations have shown that ATIII is degraded by Staphylococcus aureus V8 protease, leading to release of heparin binding fragments derived from its D helix. As heparin binding and antimicrobial activity of peptides frequently overlap, we here set out to explore possible antibacterial effects of intact and degraded ATIII. In contrast to intact ATIII, the results showed that extensive degradation of the molecule yielded fragments with antimicrobial activity. Correspondingly, the heparin-binding, helix D-derived, peptide FFFAKLNCRLYRKANKSSKLV (FFF21) of human ATIII, was found to be antimicrobial against particularly the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa. Fluorescence microscopy and electron microscopy studies demonstrated that FFF21 binds to and permeabilizes bacterial membranes. Analogously, FFF21 was found to induce membrane leakage of model anionic liposomes. In vivo, FFF21 significantly reduced P. aeruginosa infection in mice. Additionally, FFF21 displayed anti-endotoxic effects in vitro. Taken together, our results suggest novel roles for ATIII-derived peptide fragments in host defense. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

The close-packed triple helix as a possible new structural motif for collagen

DEFF Research Database (Denmark)

Bohr, Jakob; Olsen, Kasper

2010-01-01

that close packing form the underlying principle behind the structure of collagen, and the implications of this suggestion are considered. Further, it is shown that the unique zero-twist structure with no strain-twist coupling is practically identical to the close-packed triple helix. Some...

Helix Nebula - the Science Cloud: a public-private partnership to build a multidisciplinary cloud platform for data intensive science

Science.gov (United States)

Jones, Bob; Casu, Francesco

2013-04-01

The feasibility of using commercial cloud services for scientific research is of great interest to research organisations such as CERN, ESA and EMBL, to the suppliers of cloud-based services and to the national and European funding agencies. Through the Helix Nebula - the Science Cloud [1] initiative and with the support of the European Commission, these stakeholders are driving a two year pilot-phase during which procurement processes and governance issues for a framework of public/private partnership will be appraised. Three initial flagship use cases from high energy physics, molecular biology and earth-observation are being used to validate the approach, enable a cost-benefit analysis to be undertaken and prepare the next stage of the Science Cloud Strategic Plan [2] to be developed and approved. The power of Helix Nebula lies in a shared set of services for initially 3 very different sciences each supporting a global community and thus building a common e-Science platform. Of particular relevance is the ESA sponsored flagship application SuperSites Exploitation Platform (SSEP [3]) that offers the global geo-hazard community a common platform for the correlation and processing of observation data for supersites monitoring. The US-NSF Earth Cube [4] and Ocean Observatory Initiative [5] (OOI) are taking a similar approach for data intensive science. The work of Helix Nebula and its recent architecture model [6] has shown that is it technically feasible to allow publicly funded infrastructures, such as EGI [7] and GEANT [8], to interoperate with commercial cloud services. Such hybrid systems are in the interest of the existing users of publicly funded infrastructures and funding agencies because they will provide "freedom of choice" over the type of computing resources to be consumed and the manner in which they can be obtained. But to offer such freedom-of choice across a spectrum of suppliers, various issues such as intellectual property, legal responsibility

Sequence and conformational preferences at termini of α-helices in membrane proteins: role of the helix environment.

Science.gov (United States)

Shelar, Ashish; Bansal, Manju

2014-12-01

α-Helices are amongst the most common secondary structural elements seen in membrane proteins and are packed in the form of helix bundles. These α-helices encounter varying external environments (hydrophobic, hydrophilic) that may influence the sequence preferences at their N and C-termini. The role of the external environment in stabilization of the helix termini in membrane proteins is still unknown. Here we analyze α-helices in a high-resolution dataset of integral α-helical membrane proteins and establish that their sequence and conformational preferences differ from those in globular proteins. We specifically examine these preferences at the N and C-termini in helices initiating/terminating inside the membrane core as well as in linkers connecting these transmembrane helices. We find that the sequence preferences and structural motifs at capping (Ncap and Ccap) and near-helical (N' and C') positions are influenced by a combination of features including the membrane environment and the innate helix initiation and termination property of residues forming structural motifs. We also find that a large number of helix termini which do not form any particular capping motif are stabilized by formation of hydrogen bonds and hydrophobic interactions contributed from the neighboring helices in the membrane protein. We further validate the sequence preferences obtained from our analysis with data from an ultradeep sequencing study that identifies evolutionarily conserved amino acids in the rat neurotensin receptor. The results from our analysis provide insights for the secondary structure prediction, modeling and design of membrane proteins. © 2014 Wiley Periodicals, Inc.

Molecular identification of marine symbiont bacteria of gastropods from the waters of the Krakal coast Yogyakarta and its potential as a Multi-Drug Resistant (MDR) antibacterial agent

Science.gov (United States)

Bahry, Muhammad Syaifudien; Pringgenies, Delianis; Trianto, Agus

2017-01-01

The resistance of pathogenic bacteria may occur to many types of antibiotics, especially in cases of non-compliance use of antibiotics, which likely to allow the evolution of Multi-Drug Resistant (MDR) bacteria. Gastropods seas are marine invertebrates informed capable of production of secondary metabolites as antibacterial MDR. The purpose of the study was the isolation and identification of gastropod symbiont bacteria found in the waters of Krakal, Gunung Kidul, Yogyakarta, which has the ability to produce antibacterial compounds against MDR(Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae, MRSA (methicillin-Resistant Staphylococcus aureus), Staphylococcus aureus, and Staphylococcus homunis) molecular. Stages of this research began with the isolation of bacteria, bacteria screening for anti-MDR compound, mass culture, and extraction, antibacterial activity test, DNA extraction, amplification by PCR 16S rDNA and sequencing. The results of the study showed that 19 isolates of bacteria were isolated from three species of gastropods namely Littorina scabra, Cypraea moneta and Conus ebraeus. Among them, 4 isolates showed activity against MDR test bacteria (E. coli, E. cloacae, K. pneumoniae, S. aureus and S. homunis). The highest activity was displayed by code LS.G1.8 isolate with the largest inhibition zone 15.47±0.45mm on S. humonis at 250 µg/disk concentration. Isolate CM.G2.1 showed largest inhibition zone, with 21.5±0.07mm on MRSA at 1000 µg/disk concentration and isolate the largest inhibition zone CM.G2.5 14.37±0.81mm on MRSA 14.37±0.81mm at concentrations 1000 µg/disk. The molecular identification of isolates LS.G1.8 has 99% homology with Bacillus subtilis and isolates CM.G2.1 has 99% homology with Bacillus pumillus.

FPGA helix tracking algorithm for PANDA

Energy Technology Data Exchange (ETDEWEB)

Liang, Yutie; Galuska, Martin; Gessler, Thomas; Hu, Jifeng; Kuehn, Wolfgang; Lange, Jens Soeren; Muenchow, David; Spruck, Bjoern [II. Physikalisches, Giessen University (Germany); Ye, Hua [II. Physikalisches, Giessen University (Germany); Institute of High Energy Physics, Beijing (China); Collaboration: PANDA-Collaboration

2014-07-01

The PANDA detector is a general-purpose detector for physics with high luminosity cooled antiproton beams, planed to operate at the FAIR facility in Darmstadt, Germany. The central detector includes a silicon Micro Vertex Detector (MVD) and a Straw Tube Tracker (STT). Without any hardware trigger, large amounts of raw data are streaming into the data acquisition system. The data reduction task is performed in the online system by reconstruction algorithms programmed in VHDL (Very High Speed Integrated Circuit Hardware Description Language) on FPGAs (Field Programmable Gate Arrays) as first level and on a farm of GPUs or PCs as a second level. One important part in the system is the online track reconstruction. In this presentation, an online tracking finding algorithm for helix track reconstruction in the solenoidal field is shown. A performance study using C++ and the status of the VHDL implementation are presented.

Introduction of potential helix-capping residues into an engineered helical protein.

Science.gov (United States)

Parker, M H; Hefford, M A

1998-08-01

MB-1 is an engineered protein that was designed to incorporate high percentages of four amino acid residues and to fold into a four-alpha-helix bundle motif. Mutations were made in the putative loop I and III regions of this protein with the aim of increasing the stability of the helix ends. Four variants, MB-3, MB-5, MB-11 and MB-13, have replacements intended to promote formation of an 'N-capping box'. The loop I and III sequences of MB-3 (both GDLST) and MB-11 (GGDST) were designed to cause alphaL C-terminal 'capping' motifs to form in helices I and III. MB-5 has a sequence, GPDST, that places proline in a favourable position for forming beta-turns, whereas MB-13 (GLDST) has the potential to form Schellman C-capping motifs. Size-exclusion chromatography suggested that MB-1, MB-3, MB-5, MB-11 and MB-13 all form dimers, or possibly trimers. Free energies for the unfolding of each of these variants were determined by urea denaturation, with the loss of secondary structure followed by CD spectroscopy. Assuming an equilibrium between folded dimer and unfolded monomer, MB-13 had the highest apparent stability (40.5 kJ/mol, with +/-2.5 kJ/mol 95% confidence limits), followed by MB-11 (39.3+/-5.9 kJ/mol), MB-3 (36.4+/-1.7 kJ/mol), MB-5 (34.7+/-2.1 kJ/mol) and MB-1 (29.3+/-1.3 kJ/mol); the same relative stabilities of the variants were found when a folded trimer to unfolded monomer model was used to calculate stabilities. All of the variants were relatively unstable for dimeric proteins, but were significantly more stable than MB-1. These findings suggest that it might be possible to increase the stability of a protein for which the three-dimensional structure is unknown by placing amino acid residues in positions that have the potential to form helix- and turn-stabilizing motifs.

Basic Tilted Helix Bundle – A new protein fold in human FKBP25/FKBP3 and HectD1

International Nuclear Information System (INIS)

Helander, Sara; Montecchio, Meri; Lemak, Alexander; Farès, Christophe; Almlöf, Jonas; Li, Yanjun; Yee, Adelinda; Arrowsmith, Cheryl H.; Dhe-Paganon, Sirano; Sunnerhagen, Maria

2014-01-01

Highlights: • We describe the structure of a novel fold in FKBP25 and HectD. • The new fold is named the Basic Tilted Helix Bundle (BTHB) domain. • A conserved basic surface patch is presented, suggesting a functional role. - Abstract: In this paper, we describe the structure of a N-terminal domain motif in nuclear-localized FKBP25 1–73 , a member of the FKBP family, together with the structure of a sequence-related subdomain of the E3 ubiquitin ligase HectD1 that we show belongs to the same fold. This motif adopts a compact 5-helix bundle which we name the Basic Tilted Helix Bundle (BTHB) domain. A positively charged surface patch, structurally centered around the tilted helix H4, is present in both FKBP25 and HectD1 and is conserved in both proteins, suggesting a conserved functional role. We provide detailed comparative analysis of the structures of the two proteins and their sequence similarities, and analysis of the interaction of the proposed FKBP25 binding protein YY1. We suggest that the basic motif in BTHB is involved in the observed DNA binding of FKBP25, and that the function of this domain can be affected by regulatory YY1 binding and/or interactions with adjacent domains

Basic Tilted Helix Bundle – A new protein fold in human FKBP25/FKBP3 and HectD1

Energy Technology Data Exchange (ETDEWEB)

Helander, Sara; Montecchio, Meri [Department of Physics, Chemistry and Biology, Division of Chemistry, Linköping University, SE-58183 Linköping (Sweden); Lemak, Alexander [Princess Margaret Cancer Centre and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 1L7 (Canada); Northeast Structural Genomics Consortium, Toronto, Ontario (Canada); Farès, Christophe [Princess Margaret Cancer Centre and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 1L7 (Canada); Almlöf, Jonas [Department of Physics, Chemistry and Biology, Division of Chemistry, Linköping University, SE-58183 Linköping (Sweden); Li, Yanjun [Structural Genomics Consortium, University of Toronto, 101 College St, Toronto, Ontario M5G 1L7 (Canada); Yee, Adelinda [Princess Margaret Cancer Centre and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 1L7 (Canada); Northeast Structural Genomics Consortium, Toronto, Ontario (Canada); Arrowsmith, Cheryl H. [Princess Margaret Cancer Centre and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 1L7 (Canada); Northeast Structural Genomics Consortium, Toronto, Ontario (Canada); Structural Genomics Consortium, University of Toronto, 101 College St, Toronto, Ontario M5G 1L7 (Canada); Dhe-Paganon, Sirano [Structural Genomics Consortium, University of Toronto, 101 College St, Toronto, Ontario M5G 1L7 (Canada); Sunnerhagen, Maria, E-mail: maria.sunnerhagen@liu.se [Department of Physics, Chemistry and Biology, Division of Chemistry, Linköping University, SE-58183 Linköping (Sweden)

2014-04-25

Highlights: • We describe the structure of a novel fold in FKBP25 and HectD. • The new fold is named the Basic Tilted Helix Bundle (BTHB) domain. • A conserved basic surface patch is presented, suggesting a functional role. - Abstract: In this paper, we describe the structure of a N-terminal domain motif in nuclear-localized FKBP25{sub 1–73}, a member of the FKBP family, together with the structure of a sequence-related subdomain of the E3 ubiquitin ligase HectD1 that we show belongs to the same fold. This motif adopts a compact 5-helix bundle which we name the Basic Tilted Helix Bundle (BTHB) domain. A positively charged surface patch, structurally centered around the tilted helix H4, is present in both FKBP25 and HectD1 and is conserved in both proteins, suggesting a conserved functional role. We provide detailed comparative analysis of the structures of the two proteins and their sequence similarities, and analysis of the interaction of the proposed FKBP25 binding protein YY1. We suggest that the basic motif in BTHB is involved in the observed DNA binding of FKBP25, and that the function of this domain can be affected by regulatory YY1 binding and/or interactions with adjacent domains.

Diversity and abundance of epibiota on invasive and native estuarine gastropods depend on substratum and salinity

DEFF Research Database (Denmark)

Thyrring, Jakob; Thomsen, Mads Solgaard; Brunbjerg, Ane Kirstine

2015-01-01

,226 shells representing the common gastropod species in the estuary; Nassarius pauperatus, Bedeva paiva and Batillaria australs from various sites and habitats. Generalized linear models were used to model variability of richness and abundances of common functional groups and species for the above listed...... factors. The five factors accounted for 3-34% of the total deviance explained of the models, with shell type and salinity levels being the only significant factors in nine of 14 models. These results highlight an overwhelming importance of shell type and salinity in explaining estuarine epibiota......Epibiosis is a common life form in estuarine ecosystems, where shell structures in particular, provide important attachment substrate for sessile species. Many studies have quantified variation in epibiota communities against a few environmental factors, but rarely studies have accounted...

Terrestrial planet formation.

Science.gov (United States)

Righter, K; O'Brien, D P

2011-11-29

Advances in our understanding of terrestrial planet formation have come from a multidisciplinary approach. Studies of the ages and compositions of primitive meteorites with compositions similar to the Sun have helped to constrain the nature of the building blocks of planets. This information helps to guide numerical models for the three stages of planet formation from dust to planetesimals (~10(6) y), followed by planetesimals to embryos (lunar to Mars-sized objects; few 10(6) y), and finally embryos to planets (10(7)-10(8) y). Defining the role of turbulence in the early nebula is a key to understanding the growth of solids larger than meter size. The initiation of runaway growth of embryos from planetesimals ultimately leads to the growth of large terrestrial planets via large impacts. Dynamical models can produce inner Solar System configurations that closely resemble our Solar System, especially when the orbital effects of large planets (Jupiter and Saturn) and damping mechanisms, such as gas drag, are included. Experimental studies of terrestrial planet interiors provide additional constraints on the conditions of differentiation and, therefore, origin. A more complete understanding of terrestrial planet formation might be possible via a combination of chemical and physical modeling, as well as obtaining samples and new geophysical data from other planets (Venus, Mars, or Mercury) and asteroids.

FPGA helix tracking algorithm for PANDA

Energy Technology Data Exchange (ETDEWEB)

Liang, Yutie; Galuska, Martin; Gessler, Thomas; Kuehn, Wolfgang; Lange, Jens Soeren; Muenchow, David [II. Physikalisches Institut, University of Giessen (Germany); Ye, Hua [Institute of High Energy Physics, CAS (China); Collaboration: PANDA-Collaboration

2016-07-01

The PANDA detector is a general-purpose detector for physics with high luminosity cooled antiproton beams, planed to operate at the FAIR facility in Darmstadt, Germany. The central detector includes a silicon Micro Vertex Detector (MVD) and a Straw Tube Tracker (STT). Without any hardware trigger, large amounts of raw data are streaming into the data acquisition system. The data reduction task is performed in the online system by reconstruction algorithms programmed on FPGAs (Field Programmable Gate Arrays) as first level and on a farm of GPUs or PCs as a second level. One important part in the system is the online track reconstruction. In this presentation, an online tracking algorithm for helix tracking reconstruction in the solenoidal field is shown. The VHDL-based algorithm is tested with different types of events, at different event rate. Furthermore, a study of T0 extraction from the tracking algorithm is performed. A concept of simultaneous tracking and T0 determination is presented.

Triple helix networks matching knowledge demand and supply in seven Dutch horticulture Greenport regions

NARCIS (Netherlands)

Geerling-Eiff, Florentien A.; Hoes, Anne-Charlotte; Dijkshoorn-Dekker, Marijke

2017-01-01

This paper investigates the triple helix (industry, knowledge workers and governments) cooperation on knowledge co-production and valorisation for innovation, which took place in seven horticultural regions in the Netherlands. It thus provides more empirical insight into the functioning of this form

Networks of entrepreneurs driving the Triple Helix: two cases of the Dutch energy system

NARCIS (Netherlands)

Werker, C.; Ubacht, J.; Ligtvoet, A.

2017-01-01

Entrepreneurs are often envisioned as small private start-up firms operating against all odds. Here, we investigate how in the context of the Triple Helix various entrepreneurs form communities and drive institutional and technological change. To theoretically shape a socialized view of

Species-specific and transgenerational responses to increasing salinity in sympatric freshwater gastropods

Science.gov (United States)

Suski, Jamie G.; Salice, Christopher J.; Patino, Reynaldo

2012-01-01

Freshwater salinization is a global concern partly attributable to anthropogenic salt contamination. The authors examined the effects of increased salinity (as NaCl, 250-4,000 µS/cm, specific conductance) on two sympatric freshwater gastropods (Helisoma trivolvis and Physa pomillia). Life stage sensitivities were determined by exposing naive eggs or naive juveniles (through adulthood and reproduction). Additionally, progeny eggs from the juvenile-adult exposures were maintained at their respective parental salinities to examine transgenerational effects. Naive H. trivolvis eggs experienced delayed development at specific conductance > 250 µS/cm; reduced survivorship and reproduction were also seen in juvenile H. trivolvis at 4,000 µS/cm. Survival and growth of P. pomilia were not affected by increased salinity following egg or juvenile exposures. Interestingly, the progeny of H. trivolvis exposed to higher salinity may have gained tolerance to increased salinity whereas P. pomilia progeny may have experienced negative transgenerational effects. The present study demonstrates that freshwater snail species vary in their tolerance to salinization and also highlights the importance of multigenerational studies, as stressor impacts may not be readily apparent from shorter term exposures.

Phylogenetic relationships of the Cochliopinae (Rissooidea: Hydrobiidae): an enigmatic group of aquatic gastropods.

Science.gov (United States)

Liu, H P; Hershler, R; Thompson, F G

2001-10-01

Phylogenetic analysis based on a partial sequence of the mitochondrial cytochrome c oxidase subunit I gene was performed for 26 representatives of the aquatic gastropod subfamily Cochliopinae, 6 additional members of the family Hydrobiidae, and outgroup species of the families Rissoidae and Pomatiopsidae. Maximum-parsimony analysis yielded a single shortest tree which resolved two monophyletic groups: (1) a clade containing all cochliopine taxa with the exception of Antroselates and (2) a clade composed of Antroselates and the hydrobiid genus Amnicola. The clade containing both of these monophyletic groups was depicted as more closely related to members of the family Pomatiopsidae than to other hydrobiid snails which were basally positioned in our topology. New anatomical evidence supports recognition of the cochliopine and Antroselates-Amnicola clades, and structure within the monophyletic group of cochliopines is largely congruent with genitalic characters. However, the close relationship between the Pomatiopsidae and these clades is in conflict with commonly accepted classifications and suggests that a widely accepted scenario for genitalic evolution in these snails is in need of further study. Copyright 2001 Academic Press.

Consequences of simulating terrestrial N dynamics for projecting future terrestrial C storage

Science.gov (United States)

Zaehle, S.; Friend, A. D.; Friedlingstein, P.

2009-04-01

We present results of a new land surface model, O-CN, which includes a process-based coupling between the terrestrial cycling of energy, water, carbon, and nitrogen. The model represents the controls of the terrestrial nitrogen (N) cycling on carbon (C) pools and fluxes through photosynthesis, respiration, changes in allocation patterns, as well as soil organic matter decomposition, and explicitly accounts for N leaching and gaseous losses. O-CN has been shown to give realistic results in comparison to observations at a wide range of scales, including in situ flux measurements, productivity databases, and atmospheric CO2 concentration data. Notably, O-CN simulates realistic responses of net primary productivity, foliage area, and foliage N content to elevated atmospheric [CO2] as evidenced at free air carbon dioxide enrichment (FACE) sites (Duke, Oak Ridge). We re-examine earlier model-based assessments of the terrestrial C sequestration potential using a global transient O-CN simulation driven by increases in atmospheric [CO2], N deposition and climatic changes over the 21st century. We find that accounting for terrestrial N cycling about halves the potential to store C in response to increases in atmospheric CO2 concentrations; mainly due to a reduction of the net C uptake in temperate and boreal forests. Nitrogen deposition partially alleviates the effect of N limitation, but is by far not sufficient to compensate for the effect completely. These findings underline the importance of an accurate representation of nutrient limitations in future projections of the terrestrial net CO2 exchanges and therefore land-climate feedback studies.

Aquatic and Terrestrial Environment 2004

DEFF Research Database (Denmark)

Andersen, J. M.; Boutrup, S.; Bijl, L. van der

This report presents the 2004 results of the Danish National Monitoring and Assess-ment Programme for the Aquatic and Terrestrial Environments (NOVANA). 2004 was the first year in which terrestrial nature was included in the monitoring pro-gramme. The report reviews the state of the groundwater......, watercourses, lakes and marine waters and the pressures upon them and reviews the monitoring of terrestrial natural habitats and selected plants and animals. The report is based on the annual reports prepared for each subprogramme by the Topic Centres. The latter reports are mainly based on data collected...

The generalized model of polypeptide chain describing the helix-coil transition in biopolymers

International Nuclear Information System (INIS)

Mamasakhlisov, E.S.; Badasyan, A.V.; Tsarukyan, A.V.; Grigoryan, A.V.; Morozov, V.F.

2005-07-01

In this paper we summarize some results of our theoretical investigations of helix-coil transition both in single-strand (polypeptides) and two-strand (polynucleotides) macromolecules. The Hamiltonian of the Generalized Model of Polypeptide Chain (GMPC) is introduced to describe the system in which the conformations are correlated over some dimensional range Δ (it equals 3 for polypeptide, because one H-bond fixes three pairs of rotation, for double strand DNA it equals to one chain rigidity because of impossibility of loop formation on the scale less than Δ). The Hamiltonian does not contain any parameter designed especially for helix-coil transition and uses pure molecular microscopic parameters (the energy of hydrogen bond formation, reduced partition function of repeated unit, the number of repeated units fixed by one hydrogen bond, the energies of interaction between the repeated units and the solvent molecules). To calculate averages we evaluate the partition function using the transfer-matrix approach. The GMPC allowed to describe the influence of a number of factors, affecting the transition, basing on a unified microscopic approach. Thus we obtained, that solvents change transition temperature and interval in different ways, depending on type of solvent and on energy of solvent- macromolecule interaction; stacking on the background of H-bonding increases stability and decreases cooperativity of melting. For heterogeneous DNA we could analytically derive well known formulae for transition temperature and interval. In the framework of GMPC we calculate and show the difference of two order parameters of helix-coil transition - the helicity degree, and the average fraction of repeated units in helical conformation. Given article has the aim to review the results obtained during twenty years in the context of GMPC. (author)

PRESSURE - WATER and Other Data from ALPHA HELIX from 19981002 to 19990513 (NODC Accession 9900149)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature and salinity profiles were collected from CTD casts from the Alpha Helix from 02 October 1998 to 13 May 1999. These 6 CTD data sets are from two...

Alternative generation of well-aligned uniform lying helix texture in a cholesteric liquid crystal cell

Directory of Open Access Journals (Sweden)

Chia-Hua Yu

2017-10-01

Full Text Available This work demonstrates a simple approach for obtaining a well-aligned uniform lying helix (ULH texture and a tri-bistable feature at ambient temperature in a typical 90°-twisted cell filled with a short-pitch cholesteric liquid crystal. This ULH texture is obtained at room temperature from initially field-induced helix-free homeotropic state by gradually decreasing the applied voltage. Depending on the way and rate of reducing the voltage, three stable states (i.e., Grandjean planar, focal conic, and ULH are generated and switching between any two of them is realized. Moreover, the electrical operation of the cell in the ULH state enables the tunability in phase retardation via the deformation of the ULH. The observations made in this work may be useful for applications such as tunable phase modulators and energy-efficient photonic devices.

Anthropogenic transformation of the terrestrial biosphere.

Science.gov (United States)

Ellis, Erle C

2011-03-13

Human populations and their use of land have transformed most of the terrestrial biosphere into anthropogenic biomes (anthromes), causing a variety of novel ecological patterns and processes to emerge. To assess whether human populations and their use of land have directly altered the terrestrial biosphere sufficiently to indicate that the Earth system has entered a new geological epoch, spatially explicit global estimates of human populations and their use of land were analysed across the Holocene for their potential to induce irreversible novel transformation of the terrestrial biosphere. Human alteration of the terrestrial biosphere has been significant for more than 8000 years. However, only in the past century has the majority of the terrestrial biosphere been transformed into intensively used anthromes with predominantly novel anthropogenic ecological processes. At present, even were human populations to decline substantially or use of land become far more efficient, the current global extent, duration, type and intensity of human transformation of ecosystems have already irreversibly altered the terrestrial biosphere at levels sufficient to leave an unambiguous geological record differing substantially from that of the Holocene or any prior epoch. It remains to be seen whether the anthropogenic biosphere will be sustained and continue to evolve.

The role of MAPK signaling in patterning and establishing axial symmetry in the gastropod Haliotis asinina

DEFF Research Database (Denmark)

Koop, Demian; Richards, Gemma S; Wanninger, Andreas

2007-01-01

, the embryo begins to gastrulate and assumes a bilateral cleavage pattern. Here we inhibit MAPK activation in 3D with U0126 and examine its effect on the formation and patterning of the trochophore, using a suite of territory-specific markers. The head (pretrochal) region appears to maintain quadri...... (D) quadrant is intimately linked with body plan organization and in equally cleaving gastropods occurs when one of the vegetal macromeres makes contact with overlying micromeres and receives an inductive signal that activates a MAPK signaling cascade. Following the induction of the 3D macromere......-radial symmetry in U0126-treated embryos, supporting a role for MAPK signaling in 3D in establishing dorsoventral polarity in this region. Posterior (posttrochal) structures - larval musculature, shell and foot--fail to develop in MAPK inhibited trochophores. Inhibition of 3D specification by an alternative...

Histories of terrestrial planets

International Nuclear Information System (INIS)

Benes, K.

1981-01-01

The uneven historical development of terrestrial planets - Mercury, Venus, Earth, Moon and Mars - is probably due to the differences in their size, weight and rotational dynamics in association with the internal planet structure, their distance from the Sun, etc. A systematic study of extraterrestrial planets showed that the time span of internal activity was not the same for all bodies. It is assumed that the initial history of all terrestrial planets was marked with catastrophic events connected with the overall dynamic development of the solar system. In view of the fact that the cores of small terrestrial bodies cooled quicker, their geological development almost stagnated after two or three thousand million years. This is what probably happened to the Mercury and the Moon as well as the Mars. Therefore, traces of previous catastrophic events were preserved on the surface of the planets. On the other hand, the Earth is the most metamorphosed terrestrial planet and compared to the other planets appears to be atypical. Its biosphere is significantly developed as well as the other shell components, its hydrosphere and atmosphere, and its crust is considerably differentiated. (J.P.)

BAROMETRIC PRESSURE and Other Data from ALPHA HELIX from 19971010 to 19980514 (NODC Accession 9800119)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Hydrophysical, hydrochemical, and other data were collected from CTD casts in the Gulf of Alaska from the R/V Alpha Helix from 10 October 1997 to 14 May 1998. Data...

On the origin of Acochlidia and other enigmatic euthyneuran gastropods, with implications for the systematics of Heterobranchia

Directory of Open Access Journals (Sweden)

Knebelsberger Thomas

2010-10-01

Full Text Available Abstract Background A robust phylogenetic hypothesis of euthyneuran gastropods, as a basis to reconstructing their evolutionary history, is still hindered by several groups of aberrant, more or less worm-like slugs with unclear phylogenetic relationships. As a traditional "order" in the Opisthobranchia, the Acochlidia have a long history of controversial placements, among others influenced by convergent adaptation to the mainly meiofaunal habitats. The present study includes six out of seven acochlidian families in a comprehensive euthyneuran taxon sampling with special focus on minute, aberrant slugs. Since there is no fossil record of tiny, shell-less gastropods, a molecular clock was used to estimate divergence times within Euthyneura. Results Our multi-locus molecular study confirms Acochlidia in a pulmonate relationship, as sister to Eupulmonata. Previous hypotheses of opisthobranch relations, or of a common origin with other meiofaunal Euthyneura, are clearly rejected. The enigmatic amphibious and insectivorous Aitengidae incerta sedis clusters within Acochlidia, as sister to meiofaunal and brackish Pseudunelidae and limnic Acochlidiidae. Euthyneura, Opisthobranchia and Pulmonata as traditionally defined are non-monophyletic. A relaxed molecular clock approach indicates a late Palaeozoic diversification of Euthyneura and a Mesozoic origin of the major euthyneuran diversity, including Acochlidia. Conclusions The present study shows that the inclusion of small, enigmatic groups is necessary to solve deep-level phylogenetic relationships, and underlines that "pulmonate" and "opisthobranch" phylogeny, respectively, cannot be solved independently from each other. Our phylogenetic hypothesis requires reinvestigation of the traditional classification of Euthyneura: morphological synapomorphies of the traditionally defined Pulmonata and Opisthobranchia are evaluated in light of the presented phylogeny, and a redefinition of major groups is

Evaluation of a Pilot Surveillance System: Health and Environment Linked for Information Exchange in Atlanta (HELIX-Atlanta)

Science.gov (United States)

Meyer, P.; Shire, J.; Qualters, Judy; Daley, Randolph; Fiero, Leslie Todorov; Autry, Andy; Avchen, Rachel; Stock, Allison; Correa, Adolofo; Siffel, Csaba;

Riparian vegetation in the alpine connectome: Terrestrial-aquatic and terrestrial-terrestrial interactions.

Science.gov (United States)

Zaharescu, Dragos G; Palanca-Soler, Antonio; Hooda, Peter S; Tanase, Catalin; Burghelea, Carmen I; Lester, Richard N

2017-12-01

Alpine regions are under increased attention worldwide for their critical role in early biogeochemical cycles, their high sensitivity to environmental change, and as repositories of natural resources of high quality. Their riparian ecosystems, at the interface between aquatic and terrestrial environments, play important geochemical functions in the watershed and are biodiversity hotspots, despite a harsh climate and topographic setting. With climate change rapidly affecting the alpine biome, we still lack a comprehensive understanding of the extent of interactions between riparian surface, lake and catchment environments. A total of 189 glacial - origin lakes were surveyed in the Central Pyrenees to test how key elements of the lake and terrestrial environments interact at different scales to shape riparian plant composition. Secondly, we evaluated how underlying ecotope features drive the formation of natural communities potentially sensitive to environmental change and assessed their habitat distribution. At the macroscale, vegetation composition responded to pan-climatic gradients altitude and latitude, which captured in a narrow geographic area the transition between large European climatic zones. Hydrodynamics was the main catchment-scale factor connecting riparian vegetation with major water fluxes, followed by topography and geomorphology. Lake sediment Mg and Pb, and water Mn and Fe contents reflected local influences from mafic bedrock and soil water saturation. Community analysis identified four keystone ecosystems: (i) damp ecotone, (ii) snow bed-silicate bedrock, (iii) wet heath, and (iv) calcareous substrate. These communities and their connections with ecotope elements could be at risk from a number of environmental change factors including warmer seasons, snow line and lowland species advancement, increased nutrient/metal input and water level fluctuations. The results imply important natural terrestrial-aquatic linkages in the riparian environment

Modulating immunogenic properties of HIV-1 gp41 membrane-proximal external region by destabilizing six-helix bundle structure

Energy Technology Data Exchange (ETDEWEB)

Banerjee, Saikat; Shi, Heliang; Habte, Habtom H.; Qin, Yali; Cho, Michael W., E-mail: mcho@iastate.edu

2016-03-15

The C-terminal alpha-helix of gp41 membrane-proximal external region (MPER; {sup 671}NWFDITNWLWYIK{sup 683}) encompassing 4E10/10E8 epitopes is an attractive target for HIV-1 vaccine development. We previously reported that gp41-HR1-54Q, a trimeric protein comprised of the MPER in the context of a stable six-helix bundle (6HB), induced strong immune responses against the helix, but antibodies were directed primarily against the non-neutralizing face of the helix. To better target 4E10/10E8 epitopes, we generated four putative fusion intermediates by introducing double point mutations or deletions in the heptad repeat region 1 (HR1) that destabilize 6HB in varying degrees. One variant, HR1-∆10-54K, elicited antibodies in rabbits that targeted W672, I675 and L679, which are critical for 4E10/10E8 recognition. Overall, the results demonstrated that altering structural parameters of 6HB can influence immunogenic properties of the MPER and antibody targeting. Further exploration of this strategy could allow development of immunogens that could lead to induction of 4E10/10E8-like antibodies. - Highlights: • Four gp41 MPER-based immunogens that resemble fusion intermediates were generated. • C-terminal region of MPER that contains 4E10/10E8 epitopes was highly immunogenic. • Altering 6HB structure can influence immunogenic properties of the MPER. • Induced antibodies targeted multiple residues critical for 4E10/10E8 binding. • Development of immunogens based on fusion intermediates is a promising strategy.

Enhancing the innovative capacity of small firms through triple helix interactions : challenges and opportunities

NARCIS (Netherlands)

Ranga, Liana Marina; Miedema, Joost; Jorna, Rene

2008-01-01

This paper presents the results of a recent exploratory study aiming to enhance the innovative capacity of small firms in the Northern Netherlands, a region lagging behind the rest of the country in terms of economic growth and innovative capacity. The triple helix perspective is adopted to examine

Microbiological and chemical evaluation of Helix spp. snails from local and non-EU markets, utilised as food in Sardinia

Directory of Open Access Journals (Sweden)

Arianna Corda

2014-04-01

Full Text Available With this study, 28 pools of snails of the genus Helix, respectively Helix aspersa (n=24 and Helix vermiculata (n=4 were analysed. They were taken from snail farming and stores. The snails were from Sardinia, other regions of Italy, and from abroad. All the samples were examined as pool looking for these microbiological target: Salmonella spp., Listeria monocytogenes, Escherichia coli O157, Clostridium perfringens, Norovirus and Hepatitis A Virus (HAV. In the same pools, the concentration of cadmium and lead by inductively coupled plasma mass spectrometry was also determined. The levels of these heavy metals were quite high, especially for cadmium. Two samples were positive for Salmonella spp., while no sample was positive for Escherichia coli O157, HAV and Norovirus. Two samples were positive for Clostridium perfringens and 8 for Listeria monocytogenes. The microrganisms related to Listeria monocytogenes were identified using biochemical techniques, then serotyped and gene sequenced by multiple loci sequence typing technique. Furthermore, antimicrobial restistence was tested on the same samples.

Interactions between cyanobacteria and gastropods II. Impact of toxic Planktothrix agardhii on the life-history traits of Lymnaea stagnalis.

Science.gov (United States)

Lance, Emilie; Paty, Chrystelle; Bormans, Myriam; Brient, Luc; Gérard, Claudia

2007-03-30

Hepatotoxins are frequently produced by many cyanobacterial species. Microcystins (MCs) are the most frequent and widely studied hepatotoxins, with potentially hazardous repercussions on aquatic organisms. As a ubiquitous herbivore living in eutrophic freshwaters, the snail Lymnaea stagnalis (Gastropoda: Pulmonata) is particularly exposed to cyanobacteria. The toxic filamentous Planktothrix agardhii is common in temperate lakes and is therefore, a potential food resource for gastropods. In the first part of this study, we demonstrated the ingestion of toxic P. agardhii by L. stagnalis during a 5 weeks exposure, with concomitant accumulation of, on average, 60% of total MCs ingested. After 3 weeks of non-toxic food (lettuce), approximately 90% of MCs were eliminated from tissues. Here, we investigate the impact of toxic P. agardhii consumption on the life-history traits (survival, growth and fecundity), locomotion and the structure of digestive and genital glands of juvenile and adult L. stagnalis. We observed a decrease of growth regardless of age, although this was more marked in juveniles, and a reduction of fecundity in adults. Survival and locomotion were not affected. Reduction of growth and fecundity continued to be observed even after feeding of non-toxic food for 3 weeks. The structure of the digestive gland was altered during the intoxication period but not irreversibly as cells tended to recover a normal status after the 3-week detoxification period. No histopathological changes occurred in the genital gland and oocytes, and spermatozoids were present in the gonadic acini. The density of cyanobacterial suspensions used in this study was comparable to those regularly observed in lakes, particularly in eutrophic waters. These results are discussed in terms of the negative impact of toxic cyanobacteria on natural communities of freshwater gastropods, and potential cascading effects on the equilibrium and functioning of the ecosystem.

The N-terminal amphipathic helix of the topological specificity factor MinE is associated with shaping membrane curvature.

Directory of Open Access Journals (Sweden)

Yu-Ling Shih

Full Text Available Pole-to-pole oscillations of the Min proteins in Escherichia coli are required for the proper placement of the division septum. Direct interaction of MinE with the cell membrane is critical for the dynamic behavior of the Min system. In vitro, this MinE-membrane interaction led to membrane deformation; however, the underlying mechanism remained unclear. Here we report that MinE-induced membrane deformation involves the formation of an amphipathic helix of MinE(2-9, which, together with the adjacent basic residues, function as membrane anchors. Biochemical evidence suggested that the membrane association induces formation of the helix, with the helical face, consisting of A2, L3, and F6, inserted into the membrane. Insertion of this helix into the cell membrane can influence local membrane curvature and lead to drastic changes in membrane topology. Accordingly, MinE showed characteristic features of protein-induced membrane tubulation and lipid clustering in in vitro reconstituted systems. In conclusion, MinE shares common protein signatures with a group of membrane trafficking proteins in eukaryotic cells. These MinE signatures appear to affect membrane curvature.

Conservation of Three-Dimensional Helix-Loop-Helix Structure through the Vertebrate Lineage Reopens the Cold Case of Gonadotropin-Releasing Hormone-Associated Peptide.

Science.gov (United States)

Pérez Sirkin, Daniela I; Lafont, Anne-Gaëlle; Kamech, Nédia; Somoza, Gustavo M; Vissio, Paula G; Dufour, Sylvie

2017-01-01

GnRH-associated peptide (GAP) is the C-terminal portion of the gonadotropin-releasing hormone (GnRH) preprohormone. Although it was reported in mammals that GAP may act as a prolactin-inhibiting factor and can be co-secreted with GnRH into the hypophyseal portal blood, GAP has been practically out of the research circuit for about 20 years. Comparative studies highlighted the low conservation of GAP primary amino acid sequences among vertebrates, contributing to consider that this peptide only participates in the folding or carrying process of GnRH. Considering that the three-dimensional (3D) structure of a protein may define its function, the aim of this study was to evaluate if GAP sequences and 3D structures are conserved in the vertebrate lineage. GAP sequences from various vertebrates were retrieved from databases. Analysis of primary amino acid sequence identity and similarity, molecular phylogeny, and prediction of 3D structures were performed. Amino acid sequence comparison and phylogeny analyses confirmed the large variation of GAP sequences throughout vertebrate radiation. In contrast, prediction of the 3D structure revealed a striking conservation of the 3D structure of GAP1 (GAP associated with the hypophysiotropic type 1 GnRH), despite low amino acid sequence conservation. This GAP1 peptide presented a typical helix-loop-helix (HLH) structure in all the vertebrate species analyzed. This HLH structure could also be predicted for GAP2 in some but not all vertebrate species and in none of the GAP3 analyzed. These results allowed us to infer that selective pressures have maintained GAP1 HLH structure throughout the vertebrate lineage. The conservation of the HLH motif, known to confer biological activity to various proteins, suggests that GAP1 peptides may exert some hypophysiotropic biological functions across vertebrate radiation.

Conservation of Three-Dimensional Helix-Loop-Helix Structure through the Vertebrate Lineage Reopens the Cold Case of Gonadotropin-Releasing Hormone-Associated Peptide

Directory of Open Access Journals (Sweden)

Daniela I. Pérez Sirkin

2017-08-01

Full Text Available GnRH-associated peptide (GAP is the C-terminal portion of the gonadotropin-releasing hormone (GnRH preprohormone. Although it was reported in mammals that GAP may act as a prolactin-inhibiting factor and can be co-secreted with GnRH into the hypophyseal portal blood, GAP has been practically out of the research circuit for about 20 years. Comparative studies highlighted the low conservation of GAP primary amino acid sequences among vertebrates, contributing to consider that this peptide only participates in the folding or carrying process of GnRH. Considering that the three-dimensional (3D structure of a protein may define its function, the aim of this study was to evaluate if GAP sequences and 3D structures are conserved in the vertebrate lineage. GAP sequences from various vertebrates were retrieved from databases. Analysis of primary amino acid sequence identity and similarity, molecular phylogeny, and prediction of 3D structures were performed. Amino acid sequence comparison and phylogeny analyses confirmed the large variation of GAP sequences throughout vertebrate radiation. In contrast, prediction of the 3D structure revealed a striking conservation of the 3D structure of GAP1 (GAP associated with the hypophysiotropic type 1 GnRH, despite low amino acid sequence conservation. This GAP1 peptide presented a typical helix-loop-helix (HLH structure in all the vertebrate species analyzed. This HLH structure could also be predicted for GAP2 in some but not all vertebrate species and in none of the GAP3 analyzed. These results allowed us to infer that selective pressures have maintained GAP1 HLH structure throughout the vertebrate lineage. The conservation of the HLH motif, known to confer biological activity to various proteins, suggests that GAP1 peptides may exert some hypophysiotropic biological functions across vertebrate radiation.

Early Cretaceous terrestrial ecosystems in East Asia based on food-web and energy-flow models

Science.gov (United States)

Matsukawa, M.; Saiki, K.; Ito, M.; Obata, I.; Nichols, D.J.; Lockley, M.G.; Kukihara, R.; Shibata, K.

2006-01-01

In recent years, there has been global interest in the environments and ecosystems around the world. It is helpful to reconstruct past environments and ecosystems to help understand them in the present and the future. The present environments and ecosystems are an evolving continuum with those of the past and the future. This paper demonstrates the contribution of geology and paleontology to such continua. Using fossils, we can make an estimation of past population density as an ecosystem index based on food-web and energy-flow models. Late Mesozoic nonmarine deposits are distributed widely on the eastern Asian continent and contain various kinds of fossils such as fishes, amphibians, reptiles, dinosaurs, mammals, bivalves, gastropods, insects, ostracodes, conchostracans, terrestrial plants, and others. These fossil organisms are useful for late Mesozoic terrestrial ecosystem reconstruction using food-web and energy-flow models. We chose Early Cretaceous fluvio-lacustrine basins in the Choyr area, southeastern Mongolia, and the Tetori area, Japan, for these analyses and as a potential model for reconstruction of other similar basins in East Asia. The food-web models are restored based on taxa that occurred in these basins. They form four or five trophic levels in an energy pyramid consisting of rich primary producers at its base and smaller biotas higher in the food web. This is the general energy pyramid of a typical ecosystem. Concerning the population densities of vertebrate taxa in 1 km2 in these basins, some differences are recognized between Early Cretaceous and the present. For example, Cretaceous estimates suggest 2.3 to 4.8 times as many herbivores and 26.0 to 105.5 times the carnivore population. These differences are useful for the evaluation of past population densities of vertebrate taxa. Such differences may also be caused by the different metabolism of different taxa. Preservation may also be a factor, and we recognize that various problems occur in

Novel Plasma Reactor with Rotary Helix Electrode Used in Coupling of CH4 at Atmospheric Pressure

International Nuclear Information System (INIS)

Wang Dawang; Ma Tengcai

2006-01-01

At the ambient temperature and pressure a glow discharge plasma was used as a new approach for the coupling of methane with the newly-developed rotary multidentate helix electrode. In the presence of hydrogen, the effects of the input peak voltages and gas flow rates on methane conversion, C 2 single pass yield and selectivity were investigated, and then the results were compared with those from the three-disc multidentate electrode. This demonstrated, on an experimental scale, that the rotary multidentate helix electrode was better than the multidentate three-disc electrode as there was little accumulation of coke, and the C 2 yield per pass was 69.85% and C 2 selectivity over 99.14% with 70.46% methane conversion at an input peak voltage of 2300 V and 60 ml/min gas flow rate

Does terrestrial epidemiology apply to marine systems?

Science.gov (United States)

McCallum, Hamish I.; Kuris, Armand M.; Harvell, C. Drew; Lafferty, Kevin D.; Smith, Garriet W.; Porter, James

2004-01-01

Most of epidemiological theory has been developed for terrestrial systems, but the significance of disease in the ocean is now being recognized. However, the extent to which terrestrial epidemiology can be directly transferred to marine systems is uncertain. Many broad types of disease-causing organism occur both on land and in the sea, and it is clear that some emergent disease problems in marine environments are caused by pathogens moving from terrestrial to marine systems. However, marine systems are qualitatively different from terrestrial environments, and these differences affect the application of modelling and management approaches that have been developed for terrestrial systems. Phyla and body plans are more diverse in marine environments and marine organisms have different life histories and probably different disease transmission modes than many of their terrestrial counterparts. Marine populations are typically more open than terrestrial ones, with the potential for long-distance dispersal of larvae. Potentially, this might enable unusually rapid propagation of epidemics in marine systems, and there are several examples of this. Taken together, these differences will require the development of new approaches to modelling and control of infectious disease in the ocean.

Preliminarily study on the maximum handling size, prey size and species selectivity of growth hormone transgenic and non-transgenic common carp Cyprinus carpio when foraging on gastropods

Science.gov (United States)

Zhu, Tingbing; Zhang, Lihong; Zhang, Tanglin; Wang, Yaping; Hu, Wei; Olsen, Rolf Eric; Zhu, Zuoyan

2017-10-01

The present study preliminarily examined the differences in maximum handling size, prey size and species selectivity of growth hormone transgenic and non-transgenic common carp Cyprinus carpio when foraging on four gastropods species (Bellamya aeruginosa, Radix auricularia, Parafossarulus sinensis and Alocinma longicornis) under laboratory conditions. In the maximum handling size trial, five fish from each age group (1-year-old and 2-year-old) and each genotype (transgenic and non-transgenic) of common carp were individually allowed to feed on B. aeruginosa with wide shell height range. The results showed that maximum handling size increased linearly with fish length, and there was no significant difference in maximum handling size between the two genotypes. In the size selection trial, three pairs of 2-year-old transgenic and non-transgenic carp were individually allowed to feed on three size groups of B. aeruginosa. The results show that the two genotypes of C. carpio favored the small-sized group over the large-sized group. In the species selection trial, three pairs of 2-year-old transgenic and non-transgenic carp were individually allowed to feed on thin-shelled B. aeruginosa and thick-shelled R. auricularia, and five pairs of 2-year-old transgenic and non-transgenic carp were individually allowed to feed on two gastropods species (P. sinensis and A. longicornis) with similar size and shell strength. The results showed that both genotypes preferred thin-shelled Radix auricularia rather than thick-shelled B. aeruginosa, but there were no significant difference in selectivity between the two genotypes when fed on P. sinensis and A. longicornis. The present study indicates that transgenic and non-transgenic C. carpio show similar selectivity of predation on the size- and species-limited gastropods. While this information may be useful for assessing the environmental risk of transgenic carp, it does not necessarily demonstrate that transgenic common carp might

Open Innovation, Triple Helix and Regional Innovation Systems: Exploring CATAPULT Centres in the UK

Science.gov (United States)

Kerry, Christopher; Danson, Michael

2016-01-01

Through the lens of UK CATAPULT Centres this conceptual paper presents an examination of the links between open innovation, the Triple Helix model and regional innovation systems. Highlighting the importance of boundary-spanning intermediaries, the combined role of these concepts is explored in detail. A conceptual model is then proposed which…

Health and Environment Linked for Information Exchange (HELIX)-Atlanta: A CDC-NASA Joint Environmental Public Health Tracking Collaborative Project

Science.gov (United States)

Al-Hamdan, Mohammad; Luvall, Jeff; Crosson, Bill; Estes, Maury; Limaye, Ashutosh; Quattrochi, Dale; Rickman, Doug

2008-01-01

HELIX-Atlanta was developed to support current and future state and local EPHT programs to implement data linking demonstration projects which could be part of the CDC EPHT Network. HELIX-Atlanta is a pilot linking project in Atlanta for CDC to learn about the challenges the states will encounter. NASA/MSFC and the CDC are partners in linking environmental and health data to enhance public health surveillance. The use of NASA technology creates value added geospatial products from existing environmental data sources to facilitate public health linkages. Proving the feasibility of the approach is the main objective

Private Venture Capital’s Investment on University Spin-Offs: A Case Study of Tsinghua University Based on Triple Helix Model

DEFF Research Database (Denmark)

Gao, Yuchen; Hu, Yimei; Wang, Jingyi

2015-01-01

and transition economies where governments are transforming their roles. Thus the main purpose of this study is to investigate how private venture capitals’ investment willingness on university spin-offs are influenced by universities and governments under the Chinese context based on the triple helix model....... Through an in-depth case study on the interactions of triple helix actors of Tsinghua University’s spin-offs, it is found that government and university developing an environment of marketization exert positive influences on the investment willingness of private venture capitals. Whilst financial direct...

Identification of helix capping and {beta}-turn motifs from NMR chemical shifts

Energy Technology Data Exchange (ETDEWEB)

Shen Yang; Bax, Ad, E-mail: bax@nih.gov [National Institutes of Health, Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases (United States)

2012-03-15

We present an empirical method for identification of distinct structural motifs in proteins on the basis of experimentally determined backbone and {sup 13}C{sup {beta}} chemical shifts. Elements identified include the N-terminal and C-terminal helix capping motifs and five types of {beta}-turns: I, II, I Prime , II Prime and VIII. Using a database of proteins of known structure, the NMR chemical shifts, together with the PDB-extracted amino acid preference of the helix capping and {beta}-turn motifs are used as input data for training an artificial neural network algorithm, which outputs the statistical probability of finding each motif at any given position in the protein. The trained neural networks, contained in the MICS (motif identification from chemical shifts) program, also provide a confidence level for each of their predictions, and values ranging from ca 0.7-0.9 for the Matthews correlation coefficient of its predictions far exceed those attainable by sequence analysis. MICS is anticipated to be useful both in the conventional NMR structure determination process and for enhancing on-going efforts to determine protein structures solely on the basis of chemical shift information, where it can aid in identifying protein database fragments suitable for use in building such structures.

Identification of helix capping and β-turn motifs from NMR chemical shifts

International Nuclear Information System (INIS)

Shen Yang; Bax, Ad

2012-01-01

We present an empirical method for identification of distinct structural motifs in proteins on the basis of experimentally determined backbone and 13 C β chemical shifts. Elements identified include the N-terminal and C-terminal helix capping motifs and five types of β-turns: I, II, I′, II′ and VIII. Using a database of proteins of known structure, the NMR chemical shifts, together with the PDB-extracted amino acid preference of the helix capping and β-turn motifs are used as input data for training an artificial neural network algorithm, which outputs the statistical probability of finding each motif at any given position in the protein. The trained neural networks, contained in the MICS (motif identification from chemical shifts) program, also provide a confidence level for each of their predictions, and values ranging from ca 0.7–0.9 for the Matthews correlation coefficient of its predictions far exceed those attainable by sequence analysis. MICS is anticipated to be useful both in the conventional NMR structure determination process and for enhancing on-going efforts to determine protein structures solely on the basis of chemical shift information, where it can aid in identifying protein database fragments suitable for use in building such structures.

Terrestrial Steering Group. 2014. Arctic Terrestrial Biodiversity Monitoring Plan

DEFF Research Database (Denmark)

Aastrup, Peter; Aronsson, Mora; Barry, Tom

capacity and information may be currently available and (b) to outline near-term required steps to begin implementing the plan and reporting on an initial set of Arctic terrestrial biodiversity focal ecosystem component attributes. The specific objectives of the workshop were to: Identify key products...... for TSG for the next two years. Identify key components of a pan-Arctic status report for priority focal ecosystem components (FEC) attributes for policy and decision makers. Develop a prioritized set of activities to meet reporting objectives. Identify key milestones and timelines for the successful...... implementation of the Arctic Terrestrial Biodiversity Monitoring Plan for the next two years. Identify expert networks required for successful implementation of the plan. Identify key gaps and opportunities for the TSG related to plan implementation and identify near-term next steps to address gaps....

MODIS-derived terrestrial primary production [chapter 28

Science.gov (United States)

Maosheng Zhao; Steven Running; Faith Ann Heinsch; Ramakrishna Nemani

2011-01-01

Temporal and spatial changes in terrestrial biological productivity have a large impact on humankind because terrestrial ecosystems not only create environments suitable for human habitation, but also provide materials essential for survival, such as food, fiber and fuel. A recent study estimated that consumption of terrestrial net primary production (NPP; a list of...

The Planetary Terrestrial Analogues Library (PTAL)

Science.gov (United States)

Werner, S. C.; Dypvik, H.; Poulet, F.; Rull Perez, F.; Bibring, J.-P.; Bultel, B.; Casanova Roque, C.; Carter, J.; Cousin, A.; Guzman, A.; Hamm, V.; Hellevang, H.; Lantz, C.; Lopez-Reyes, G.; Manrique, J. A.; Maurice, S.; Medina Garcia, J.; Navarro, R.; Negro, J. I.; Neumann, E. R.; Pilorget, C.; Riu, L.; Sætre, C.; Sansano Caramazana, A.; Sanz Arranz, A.; Sobron Grañón, F.; Veneranda, M.; Viennet, J.-C.; PTAL Team

2018-04-01

The Planetary Terrestrial Analogues Library project aims to build and exploit a spectral data base for the characterisation of the mineralogical and geological evolution of terrestrial planets and small solar system bodies.

Stonlach content analyses of Gilchristella aestuarius and Hepsetia ...

African Journals Online (AJOL)

Apseudes digitalis. 80 2,2. 6. 5. Decapoda. Zoea larvae. 6 1,0. 3. 2. Unidentified larvae. 0,3. 2. 0. Insecta. Chironomidae larvae. 810 8,1. 67. 0. 13,5. 65. 13. Terrestrial insects. 2 0,4. 4. 0. Pupae. 22 1,1. 4. 2. Arachnida. Araneida. <0,05. 2. 0. Mollusca. Lamellibranch veligers. 9 <0,05. 8. 0 2240 7,5. 69. 6. Gastropod veligers.

Helix-length compensation studies reveal the adaptability of the VS ribozyme architecture

OpenAIRE

Lacroix-Labonté, Julie; Girard, Nicolas; Lemieux, Sébastien; Legault, Pascale

2011-01-01

Compensatory mutations in RNA are generally regarded as those that maintain base pairing, and their identification forms the basis of phylogenetic predictions of RNA secondary structure. However, other types of compensatory mutations can provide higher-order structural and evolutionary information. Here, we present a helix-length compensation study for investigating structure–function relationships in RNA. The approach is demonstrated for stem-loop I and stem-loop V of the Neurospora VS riboz...

Expression of the helix-loop-helix protein inhibitor of DNA binding-1 (ID-1) is activated by all-trans retinoic acid in normal human keratinocytes

International Nuclear Information System (INIS)

Villano, C.M.; White, L.A.

2006-01-01

The ID (inhibitor of differentiation or DNA binding) helix-loop-helix proteins are important mediators of cellular differentiation and proliferation in a variety of cell types through regulation of gene expression. Overexpression of the ID proteins in normal human keratinocytes results in extension of culture lifespan, indicating that these proteins are important for epidermal differentiation. Our hypothesis is that the ID proteins are targets of the retinoic acid signaling pathway in keratinocytes. Retinoids, vitamin A analogues, are powerful regulators of cell growth and differentiation and are widely used in the prevention and treatment of a variety of cancers in humans. Furthermore, retinoic acid is necessary for the maintenance of epithelial differentiation and demonstrates an inhibitory action on skin carcinogenesis. We examined the effect of all-trans retinoic acid on expression of ID-1, -2, -3, and -4 in normal human keratinocytes and found that exposure of these cells to all-trans retinoic acid causes an increase in both ID-1 and ID-3 gene expression. Furthermore, our data show that this increase is mediated by increased transcription involving several cis-acting elements in the distal portion of the promoter, including a CREB-binding site, an Egr1 element, and an YY1 site. These data demonstrate that the ID proteins are direct targets of the retinoic acid signaling pathway. Given the importance of the ID proteins to epidermal differentiation, these results suggest that IDs may be mediating some of the effects of all-trans retinoic acid in normal human keratinocytes

Terrestrial ecosystems and biodiversity

CSIR Research Space (South Africa)

Davis-Reddy, Claire

2017-10-01

Full Text Available Ecoregions Terrestrial Biomes Protected Areas Climate Risk and Vulnerability: A Handbook for Southern Africa | 75 7.2. Non-climatic drivers of ecosystem change 7.2.1. Land-use change, habitat loss and fragmentation Land-use change and landscape... concentrations of endemic plant and animal species, but these mainly occur in areas that are most threatened by human activity. Diverse terrestrial ecosystems in the region include tropical and sub-tropical forests, deserts, savannas, grasslands, mangroves...

Constitutive Overexpression of the Basic Helix-Loop-Helix Nex1/MATH-2 Transcription Factor Promotes Neuronal Differentiation of PC12 Cells and Neurite Regeneration

Science.gov (United States)

Uittenbogaard, Martine; Chiaramello, Anne

2009-01-01

Elucidation of the intricate transcriptional pathways leading to neural differentiation and the establishment of neuronal identity is critical to the understanding and design of therapeutic approaches. Among the important players, the basic helix-loop-helix (bHLH) transcription factors have been found to be pivotal regulators of neurogenesis. In this study, we investigate the role of the bHLH differentiation factor Nex1/MATH-2 in conjunction with the nerve growth factor (NGF) signaling pathway using the rat phenochromocytoma PC12 cell line. We report that the expression of Nex1 protein is induced after 5 hr of NGF treatment and reaches maximal levels at 24 hr, when very few PC12 cells have begun extending neurites and ceased cell division. Furthermore, our study demonstrates that Nex1 has the ability to trigger neuronal differentiation of PC12 cells in the absence of neurotrophic factor. We show that Nex1 plays an important role in neurite outgrowth and has the capacity to regenerate neurite outgrowth in the absence of NGF. These results are corroborated by the fact that Nex1 targets a repertoire of distinct types of genes associated with neuronal differentiation, such as GAP-43, βIII-tubulin, and NeuroD. In addition, our findings show that Nex1 up-regulates the expression of the mitotic inhibitor p21WAF1, thus linking neuronal differentiation to cell cycle withdrawal. Finally, our studies show that overexpression of a Nex1 mutant has the ability to block the execution of NGF-induced differentiation program, suggesting that Nex1 may be an important effector of the NGF signaling pathway. PMID:11782967

Net (ERP/SAP2) one of the Ras-inducible TCFs, has a novel inhibitory domain with resemblance to the helix-loop-helix motif.

Science.gov (United States)

Maira, S M; Wurtz, J M; Wasylyk, B

1996-11-01

The three ternary complex factors (TCFs), Net (ERP/ SAP-2), ELK-1 and SAP-1, are highly related ets oncogene family members that participate in the response of the cell to Ras and growth signals. Understanding the different roles of these factors will provide insights into how the signals result in coordinate regulation of the cell. We show that Net inhibits transcription under basal conditions, in which SAP-1a is inactive and ELK-1 stimulates. Repression is mediated by the NID, the Net Inhibitory Domain of about 50 amino acids, which autoregulates the Net protein and also inhibits when it is isolated in a heterologous fusion protein. Net is particularly sensitive to Ras activation. Ras activates Net through the C-domain, which is conserved between the three TCFs, and the NID is an efficient inhibitor of Ras activation. The NID, as well as more C-terminal sequences, inhibit DNA binding. Net is more refractory to DNA binding than the other TCFs, possibly due to the presence of multiple inhibitory elements. The NID may adopt a helix-loop-helix (HLH) structure, as evidenced by homology to other HLH motifs, structure predictions, model building and mutagenesis of critical residues. The sequence resemblance with myogenic factors suggested that Net may form complexes with the same partners. Indeed, we found that Net can interact in vivo with the basic HLH factor, E47. We propose that Net is regulated at the level of its latent DNA-binding activity by protein interactions and/or phosphorylation. Net may form complexes with HLH proteins as well as SRF on specific promotor sequences. The identification of the novel inhibitory domain provides a new inroad into exploring the different roles of the ternary complex factors in growth control and transformation.

Nuclear receptor ligand-binding domains: reduction of helix H12 dynamics to favour crystallization

Energy Technology Data Exchange (ETDEWEB)

Nahoum, Virginie; Lipski, Alexandra; Quillard, Fabien; Guichou, Jean-François [INSERM, U554, 34090 Montpellier (France); Université de Montpellier, CNRS, UMR5048, Centre de Biochimie Structurale (CBS), 34090 Montpellier (France); Boublik, Yvan [CNRS, UMR5237, Centre de Recherche de Biochimie Macromoléculaire (CRBM), 34293 Montpellier (France); Pérez, Efrèn [Universidade de Vigo, Departamento de Quimica Organica, Facultad de Química, 36310 Vigo (Spain); Germain, Pierre [Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), BP 10142, 67404 Illkirch CEDEX (France); Lera, Angel R. de [Universidade de Vigo, Departamento de Quimica Organica, Facultad de Química, 36310 Vigo (Spain); Bourguet, William, E-mail: bourguet@cbs.cnrs.fr [INSERM, U554, 34090 Montpellier (France); Université de Montpellier, CNRS, UMR5048, Centre de Biochimie Structurale (CBS), 34090 Montpellier (France)

2008-07-01

Attempts have been made to crystallize the ligand-binding domain of the human retinoid X receptor in complex with a variety of newly synthesized ligands. An inverse correlation was observed between the ‘crystallizability’ and the structural dynamics of the various receptor–ligand complexes. Crystallization trials of the human retinoid X receptor α ligand-binding domain (RXRα LBD) in complex with various ligands have been carried out. Using fluorescence anisotropy, it has been found that when compared with agonists these small-molecule effectors enhance the dynamics of the RXRα LBD C-terminal helix H12. In some cases, the mobility of this helix could be dramatically reduced by the addition of a 13-residue co-activator fragment (CoA). In keeping with these observations, crystals have been obtained of the corresponding ternary RXRα LBD–ligand–CoA complexes. In contrast, attempts to crystallize complexes with a highly mobile H12 remained unsuccessful. These experimental observations substantiate the previously recognized role of co-regulator fragments in facilitating the crystallization of nuclear receptor LBDs.

Utilization of the terrestrial cyanobacteria

Science.gov (United States)

Katoh, Hiroshi; Tomita-Yokotani, Kaori; Furukawa, Jun; Kimura, Shunta; Yokoshima, Mika; Yamaguchi, Yuji; Takenaka, Hiroyuki

The terrestrial, N _{2}-fixing cyanobacterium, Nostoc commune has expected to utilize for agriculture, food and terraforming cause of its extracellular polysaccharide, desiccation tolerance and nitrogen fixation. Previously, the first author indicated that desiccation related genes were analyzed and the suggested that the genes were related to nitrogen fixation and metabolisms. In this report, we suggest possibility of agriculture, using the cyanobacterium. Further, we also found radioactive compounds accumulated N. commune (cyanobacterium) in Fukushima, Japan after nuclear accident. Thus, it is investigated to decontaminate radioactive compounds from the surface soil by the cyanobacterium and showed to accumulate radioactive compounds using the cyanobacterium. We will discuss utilization of terrestrial cyanobacteria under closed environment. Keyword: Desiccation, terrestrial cyanobacteria, bioremediation, agriculture

Fabrication experiments for large helix heat exchangers

International Nuclear Information System (INIS)

Burgsmueller, P.

1978-01-01

The helical tube has gained increasing attention as a heat transfer element for various kinds of heat exchangers over the last decade. Regardless of reactor type and heat transport medium, nuclear steam generators of the helix type are now in operation, installlation, fabrication or in the project phase. As a rule, projects are based on the extrapolation of existing technologies. In the particlular case of steam generators for HTGR power stations, however, existing experience is with steam generators of up to about 2 m diameter whereas several projects involve units more than twice as large. For this reason it was felt that a fabrication experiment was necessary in order to verify the feasibility of modern steam generator designs. A test rig was erected in the SULZER steam generator shops at Mantes, France, and skilled personnel and conventional production tools were employed in conducting experiments relating to the coiling, handling and threading of large helices. (Auth.)

Chain length dependence of the helix orientation in Langmuir-Blodgett monolayers of alpha-helical diblock copolypeptides

NARCIS (Netherlands)

Nguyen, Le-Thu T.; Ardana, Aditya; Vorenkamp, Eltjo J.; ten Brinke, Gerrit; Schouten, Arend J.

2010-01-01

The effect of chain length on the helix orientation of alpha-helical diblock copolypeptides in Langmuir and Langmuir-Blodgett monolayers is reported for the first time. Amphiphilic diblock copolypeptides (PLGA-b-PMLGSLGs) of poly(alpha-L-glutamic acid) (PLGA) and

"helix Nebula - the Science Cloud", a European Science Driven Cross-Domain Initiative Implemented in via AN Active Ppp Set-Up

Science.gov (United States)

Lengert, W.; Mondon, E.; Bégin, M. E.; Ferrer, M.; Vallois, F.; DelaMar, J.

2015-12-01

Helix Nebula, a European science cross-domain initiative building on an active PPP, is aiming to implement the concept of an open science commons[1] while using a cloud hybrid model[2] as the proposed implementation solution. This approach allows leveraging and merging of complementary data intensive Earth Science disciplines (e.g. instrumentation[3] and modeling), without introducing significant changes in the contributors' operational set-up. Considering the seamless integration with life-science (e.g. EMBL), scientific exploitation of meteorological, climate, and Earth Observation data and models open an enormous potential for new big data science. The work of Helix Nebula has shown that is it feasible to interoperate publicly funded infrastructures, such as EGI [5] and GEANT [6], with commercial cloud services. Such hybrid systems are in the interest of the existing users of publicly funded infrastructures and funding agencies because they will provide "freedom and choice" over the type of computing resources to be consumed and the manner in which they can be obtained. But to offer such freedom and choice across a spectrum of suppliers, various issues such as intellectual property, legal responsibility, service quality agreements and related issues need to be addressed. Finding solutions to these issues is one of the goals of the Helix Nebula initiative. [1] http://www.egi.eu/news-and-media/publications/OpenScienceCommons_v3.pdf [2] http://www.helix-nebula.eu/events/towards-the-european-open-science-cloud [3] e.g. https://sentinel.esa.int/web/sentinel/sentinel-data-access [5] http://www.egi.eu/ [6] http://www.geant.net/

Terrestrial and extraterrestrial fullerenes

Energy Technology Data Exchange (ETDEWEB)

Heymann, D.; Jenneskens, L.W.; Jehlicka, J; Koper, C.; Vlietstra, E. [Rice Univ, Houston, TX (United States). Dept. of Earth Science

2003-07-01

This paper reviews reports of occurrences of fullerenes in circumstellar media, interstellar media, meteorites, interplanetary dust particles (IDPs), lunar rocks, hard terrestrial rocks from Shunga (Russia), Sudbury (Canada) and Mitov (Czech Republic), coal, terrestrial sediments from the Cretaceous-Tertiary-Boundary and Pennian-Triassic-Boundary, fulgurite, ink sticks, dinosaur eggs, and a tree char. The occurrences are discussed in the context of known and postulated processes of fullerene formation, including the suggestion that some natural fullerenes might have formed from biological (algal) remains.

Tectus niloticus (Tegulidae, Gastropod as a Novel Vector of Ciguatera Poisoning: Clinical Characterization and Follow-Up of a Mass Poisoning Event in Nuku Hiva Island (French Polynesia

Directory of Open Access Journals (Sweden)

Clémence Mahana iti Gatti

2018-02-01

Full Text Available Ciguatera fish poisoning (CFP is the most prevalent non-bacterial food-borne form of poisoning in French Polynesia, which results from the consumption of coral reef fish naturally contaminated with ciguatoxins produced by dinoflagellates in the genus Gambierdiscus. Since the early 2000s, this French territory has also witnessed the emergence of atypical forms of ciguatera, known as ciguatera shellfish poisoning (CSP, associated with the consumption of marine invertebrates. In June 2014, nine tourists simultaneously developed a major and persistent poisoning syndrome following the consumption of the gastropod Tectus niloticus collected in Anaho, a secluded bay of Nuku Hiva Island (Marquesas Archipelago, French Polynesia. The unusual nature and severity of this event prompted a multidisciplinary investigation in order to characterize the etiology and document the short/long-term health consequences of this mass-poisoning event. This paper presents the results of clinical investigations based on hospital medical records, medical follow-up conducted six and 20 months post-poisoning, including a case description. This study is the first to describe the medical signature of T. niloticus poisoning in French Polynesia and contributed to alerting local authorities about the potential health hazards associated with the consumption of this gastropod, which is highly prized by local communities in Pacific island countries and territories.

Tectus niloticus (Tegulidae, Gastropod) as a Novel Vector of Ciguatera Poisoning: Clinical Characterization and Follow-Up of a Mass Poisoning Event in Nuku Hiva Island (French Polynesia).

Science.gov (United States)

Gatti, Clémence Mahana Iti; Lonati, Davide; Darius, Hélène Taiana; Zancan, Arturo; Roué, Mélanie; Schicchi, Azzurra; Locatelli, Carlo Alessandro; Chinain, Mireille

2018-02-28

Ciguatera fish poisoning (CFP) is the most prevalent non-bacterial food-borne form of poisoning in French Polynesia, which results from the consumption of coral reef fish naturally contaminated with ciguatoxins produced by dinoflagellates in the genus Gambierdiscus . Since the early 2000s, this French territory has also witnessed the emergence of atypical forms of ciguatera, known as ciguatera shellfish poisoning (CSP), associated with the consumption of marine invertebrates. In June 2014, nine tourists simultaneously developed a major and persistent poisoning syndrome following the consumption of the gastropod Tectus niloticus collected in Anaho, a secluded bay of Nuku Hiva Island (Marquesas Archipelago, French Polynesia). The unusual nature and severity of this event prompted a multidisciplinary investigation in order to characterize the etiology and document the short/long-term health consequences of this mass-poisoning event. This paper presents the results of clinical investigations based on hospital medical records, medical follow-up conducted six and 20 months post-poisoning, including a case description. This study is the first to describe the medical signature of T. niloticus poisoning in French Polynesia and contributed to alerting local authorities about the potential health hazards associated with the consumption of this gastropod, which is highly prized by local communities in Pacific island countries and territories.

Tectus niloticus (Tegulidae, Gastropod) as a Novel Vector of Ciguatera Poisoning: Clinical Characterization and Follow-Up of a Mass Poisoning Event in Nuku Hiva Island (French Polynesia)

Science.gov (United States)

Lonati, Davide; Zancan, Arturo; Schicchi, Azzurra; Locatelli, Carlo Alessandro; Chinain, Mireille

2018-01-01

Ciguatera fish poisoning (CFP) is the most prevalent non-bacterial food-borne form of poisoning in French Polynesia, which results from the consumption of coral reef fish naturally contaminated with ciguatoxins produced by dinoflagellates in the genus Gambierdiscus. Since the early 2000s, this French territory has also witnessed the emergence of atypical forms of ciguatera, known as ciguatera shellfish poisoning (CSP), associated with the consumption of marine invertebrates. In June 2014, nine tourists simultaneously developed a major and persistent poisoning syndrome following the consumption of the gastropod Tectus niloticus collected in Anaho, a secluded bay of Nuku Hiva Island (Marquesas Archipelago, French Polynesia). The unusual nature and severity of this event prompted a multidisciplinary investigation in order to characterize the etiology and document the short/long-term health consequences of this mass-poisoning event. This paper presents the results of clinical investigations based on hospital medical records, medical follow-up conducted six and 20 months post-poisoning, including a case description. This study is the first to describe the medical signature of T. niloticus poisoning in French Polynesia and contributed to alerting local authorities about the potential health hazards associated with the consumption of this gastropod, which is highly prized by local communities in Pacific island countries and territories. PMID:29495579

Probing the mechanistic role of the long α-helix in subunit L of respiratory Complex I from Escherichia coli by site-directed mutagenesis

Science.gov (United States)

Belevich, Galina; Knuuti, Juho; Verkhovsky, Michael I; Wikström, Mårten; Verkhovskaya, Marina

2011-01-01

The C-terminus of the NuoL subunit of Complex I includes a long amphipathic α-helix positioned parallel to the membrane, which has been considered to function as a piston in the proton pumping machinery. Here, we have introduced three types of mutations into the nuoL gene to test the piston-like function. First, NuoL was truncated at its C- and N-termini, which resulted in low production of a fragile Complex I with negligible activity. Second, we mutated three partially conserved residues of the amphipathic α-helix: Asp and Lys residues and a Pro were substituted for acidic, basic or neutral residues. All these variants exhibited almost a wild-type phenotype. Third, several substitutions and insertions were made to reduce rigidity of the amphipathic α-helix, and/or to change its geometry. Most insertions/substitutions resulted in a normal growth phenotype, albeit often with reduced stability of Complex I. In contrast, insertion of six to seven amino acids at a site of the long α-helix between NuoL and M resulted in substantial loss of proton pumping efficiency. The implications of these results for the proton pumping mechanism of Complex I are discussed. PMID:22060017

Effect of TFE on the Helical Content of AK17 and HAL-1 Peptides: Theoretical Insights into the Mechanism of Helix Stabilization.

Science.gov (United States)

Vymětal, Jiří; Bednárová, Lucie; Vondrášek, Jiří

2016-02-18

Fluorinated alcohols such as 2,2,2-trifluoroethanol (TFE) are among the most frequently used cosolvents in experiment studies of peptides. They have significant effects on secondary structure and a particularly strong promotion of α-helix is induced by TFE. In this study we validated recently proposed force field parameters for TFE in molecular dynamics simulations with two model peptides-alanine-rich AK-17 and antimicrobial peptide halictine-1 (HAL-1). In the case of HAL-1, we characterized the effect of TFE on this peptide experimentally by ECD spectroscopy. Our TFE model in question reproduced the helix-promoting effect of TFE and provided insight into the mechanisms of TFE action on peptides. Our simulations confirmed the preferential interaction of TFE molecules with α-helices, although the TFE molecules accumulate in the vicinity of the peptides in various conformations. Moreover, we observed a significant effect of TFE on the thermodynamics of the helix-coil transition and a change in local conformational preferences in the unfolded (coil) state induced by TFE. In addition, our simulation-based analysis suggests that different mechanisms participate in helix stabilization in both model peptides in water and TFE solution. Our results thus support the picture of complex TFE action on peptides that is further diversified by the identity and intrinsic properties of the peptide.

Parallel Computing for Terrestrial Ecosystem Carbon Modeling

International Nuclear Information System (INIS)

Wang, Dali; Post, Wilfred M.; Ricciuto, Daniel M.; Berry, Michael

2011-01-01

Terrestrial ecosystems are a primary component of research on global environmental change. Observational and modeling research on terrestrial ecosystems at the global scale, however, has lagged behind their counterparts for oceanic and atmospheric systems, largely because the unique challenges associated with the tremendous diversity and complexity of terrestrial ecosystems. There are 8 major types of terrestrial ecosystem: tropical rain forest, savannas, deserts, temperate grassland, deciduous forest, coniferous forest, tundra, and chaparral. The carbon cycle is an important mechanism in the coupling of terrestrial ecosystems with climate through biological fluxes of CO 2 . The influence of terrestrial ecosystems on atmospheric CO 2 can be modeled via several means at different timescales. Important processes include plant dynamics, change in land use, as well as ecosystem biogeography. Over the past several decades, many terrestrial ecosystem models (see the 'Model developments' section) have been developed to understand the interactions between terrestrial carbon storage and CO 2 concentration in the atmosphere, as well as the consequences of these interactions. Early TECMs generally adapted simple box-flow exchange models, in which photosynthetic CO 2 uptake and respiratory CO 2 release are simulated in an empirical manner with a small number of vegetation and soil carbon pools. Demands on kinds and amount of information required from global TECMs have grown. Recently, along with the rapid development of parallel computing, spatially explicit TECMs with detailed process based representations of carbon dynamics become attractive, because those models can readily incorporate a variety of additional ecosystem processes (such as dispersal, establishment, growth, mortality etc.) and environmental factors (such as landscape position, pest populations, disturbances, resource manipulations, etc.), and provide information to frame policy options for climate change

Cable-type flexible lithium ion battery based on hollow multi-helix electrodes

Energy Technology Data Exchange (ETDEWEB)

Kwon, Yo Han; Woo, Sang-Wook; Jung, Hye-Ran; Yu, Hyung Kyun; Kim, Kitae; Oh, Byung Hun; Ahn, Soonho; Kim, Je Young [Battery R and D, LG Chem, Ltd., 104-1 Moonji-dong, Yuseong-gu, Daejeon (Korea, Republic of); Lee, Sang-Young [School of Chemical Engineering, Kangwon National University, Chuncheon, Kangwondo (Korea, Republic of); Song, Seung-Wan [Graduate School of Green Energy Technology, Department of Fine Chemical Engineering and Applied Chemistry, Chungnam National University, Daejeon (Korea, Republic of); Cho, Jaephil [School of Energy Engineering and Converging Research Center for Innovative Battery Technologies, Ulsan National Institute of Science and Technology (UNIST), Ulsan (Korea, Republic of); Shin, Heon-Cheol [School of Materials Science and Engineering, Pusan National University, Busan (Korea, Republic of)

2012-10-02

The mechanical flexibility of a cable-type battery reaches levels far beyond what is possible with conventional designs. The hollow-spiral (helical) multi-helix anode architecture is critical to the robustness under mechanical stress and facilitates electrolyte wetting of the battery components. This design enables the battery to reliably power an LED screen or an MP3 player even under severe mechanical twisting and bending. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Modeling of arylamide helix mimetics in the p53 peptide binding site of hDM2 suggests parallel and anti-parallel conformations are both stable.

Directory of Open Access Journals (Sweden)

Jonathan C Fuller

Full Text Available The design of novel α-helix mimetic inhibitors of protein-protein interactions is of interest to pharmaceuticals and chemical genetics researchers as these inhibitors provide a chemical scaffold presenting side chains in the same geometry as an α-helix. This conformational arrangement allows the design of high affinity inhibitors mimicking known peptide sequences binding specific protein substrates. We show that GAFF and AutoDock potentials do not properly capture the conformational preferences of α-helix mimetics based on arylamide oligomers and identify alternate parameters matching solution NMR data and suitable for molecular dynamics simulation of arylamide compounds. Results from both docking and molecular dynamics simulations are consistent with the arylamides binding in the p53 peptide binding pocket. Simulations of arylamides in the p53 binding pocket of hDM2 are consistent with binding, exhibiting similar structural dynamics in the pocket as simulations of known hDM2 binders Nutlin-2 and a benzodiazepinedione compound. Arylamide conformations converge towards the same region of the binding pocket on the 20 ns time scale, and most, though not all dihedrals in the binding pocket are well sampled on this timescale. We show that there are two putative classes of binding modes for arylamide compounds supported equally by the modeling evidence. In the first, the arylamide compound lies parallel to the observed p53 helix. In the second class, not previously identified or proposed, the arylamide compound lies anti-parallel to the p53 helix.

CAXIAS DO SUL TECHNOLOGY INCUBATOR: TECHNOLOGICAL INNOVATION THROUGH THE TRIPLE HELIX

Directory of Open Access Journals (Sweden)

Priscila Bresolin Tisott

2014-09-01

on investment in the form of registered patents, attracting new students and recognition as a technological, entrepreneurial and innovative university. The perceived benefits for the industrial sector are training and development for businesses and entrepreneurs, while the municipal government perceives the reduced number of businesses failing and the financial returns, in the form of taxes, as benefits. The findings show that the Triple Helix concept developed by Etzkowitz (2009 plays a cooperative and participatory role in the Technology Incubator, even though it could be applied to more segments of society.

Phason thermal transport of three-helix state in insulating chiral magnets

Science.gov (United States)

Tatara, Gen

2018-06-01

Thermal dynamics of the three-helix state in a chiral magnet is studied based on a phason representation. Although phason representation is convenient for intuitive description, it is not straightforwardly compatible with microscopic linear response calculation of transport phenomena, because it is a (semi)macroscopic picture obtained by a coarse graining. By separating the slow phason mode and fast magnon mode, we show that phason thermal dynamics is driven by thermal magnon flow via the spin-transfer effect. The magnon and phason velocities are calculated by use of thermal vector potential formalism.

When Triple Helix Unravels: A Multi-Case Analysis of Failures in Industry-University Cooperative Research Centres

Science.gov (United States)

Gray, Denis; Sundstrom, Eric; Tornatzky, Louis G.; McGowen, Lindsey

2011-01-01

Cooperative research centres (CRCs) increasingly foster Triple Helix (industry-university-government) collaboration and represent significant vehicles for cooperation across sectors, the promotion of knowledge and technology transfer and ultimately the acceleration of innovation. A growing social science literature on CRCs focuses on their…

Mathematical modeling and design parameters of crushing machines with variable-pitch helix of the screw

Directory of Open Access Journals (Sweden)

Pelenko V. V.

2017-11-01

Full Text Available From the point of view of the effectiveness of the top cutting unit, the helix angle in the end portion of the screw is the most important and characteristic parameter, as it determines the pressure of the meat material in the zone of interaction of a knife and grate. The importance of solving the problem of mathematical modeling of geometry is due to the need to address the problem of minimizing the reverse flow of the food material when injecting into the cutting zone, as the specified effect of "locking" significantly reduces the performance of the transfer process, increases energy consumption of the equipment and entails the deterioration of the quality of the raw materials output. The problem of determining the length of the helix variable pitch for screw chopper food materials has been formulated and solved by methods of differential geometry. The task of correct description of the law of changing the angle of helix inclination along its length has been defined in this case as a key to provide the required dependence of this angle tangent on the angle of the radius-vector of the circle. It has been taken into account that the reduction in the pitch of the screw in the direction of the product delivery should occur at a decreasing rate. The parametric equation of the helix has been written in the form of three functional dependencies of the corresponding cylindrical coordinates. Based on the wide range analysis and significant number of models of tops from different manufacturers the boundaries of possible changes in the angles of inclination of the helical line of the first and last turns of the screw have been identified. The auger screw length is determined mathematically in the form of an analytical relationship and both as a function of the variable angle of its rise, and as a function of the rotation angle of the radius-vector of the circle generatrix, which makes it possible to expand the design possibilities of this node. Along

Fluctuations in the DNA double helix

Science.gov (United States)

Peyrard, M.; López, S. C.; Angelov, D.

2007-08-01

DNA is not the static entity suggested by the famous double helix structure. It shows large fluctuational openings, in which the bases, which contain the genetic code, are temporarily open. Therefore it is an interesting system to study the effect of nonlinearity on the physical properties of a system. A simple model for DNA, at a mesoscopic scale, can be investigated by computer simulation, in the same spirit as the original work of Fermi, Pasta and Ulam. These calculations raise fundamental questions in statistical physics because they show a temporary breaking of equipartition of energy, regions with large amplitude fluctuations being able to coexist with regions where the fluctuations are very small, even when the model is studied in the canonical ensemble. This phenomenon can be related to nonlinear excitations in the model. The ability of the model to describe the actual properties of DNA is discussed by comparing theoretical and experimental results for the probability that base pairs open an a given temperature in specific DNA sequences. These studies give us indications on the proper description of the effect of the sequence in the mesoscopic model.

Microplastics as an emerging threat to terrestrial ecosystems.

Science.gov (United States)

de Souza Machado, Anderson Abel; Kloas, Werner; Zarfl, Christiane; Hempel, Stefan; Rillig, Matthias C

2018-04-01

Microplastics (plastics plastic litter or from direct environmental emission. Their potential impacts in terrestrial ecosystems remain largely unexplored despite numerous reported effects on marine organisms. Most plastics arriving in the oceans were produced, used, and often disposed on land. Hence, it is within terrestrial systems that microplastics might first interact with biota eliciting ecologically relevant impacts. This article introduces the pervasive microplastic contamination as a potential agent of global change in terrestrial systems, highlights the physical and chemical nature of the respective observed effects, and discusses the broad toxicity of nanoplastics derived from plastic breakdown. Making relevant links to the fate of microplastics in aquatic continental systems, we here present new insights into the mechanisms of impacts on terrestrial geochemistry, the biophysical environment, and ecotoxicology. Broad changes in continental environments are possible even in particle-rich habitats such as soils. Furthermore, there is a growing body of evidence indicating that microplastics interact with terrestrial organisms that mediate essential ecosystem services and functions, such as soil dwelling invertebrates, terrestrial fungi, and plant-pollinators. Therefore, research is needed to clarify the terrestrial fate and effects of microplastics. We suggest that due to the widespread presence, environmental persistence, and various interactions with continental biota, microplastic pollution might represent an emerging global change threat to terrestrial ecosystems. © 2017 John Wiley & Sons Ltd.

Effect of secondary structure on the potential of mean force for poly-L-lysine in the alpha-Helix and beta-sheet conformations

Energy Technology Data Exchange (ETDEWEB)

Grigsby, J.J.; Blanch, H.W.; Prausnitz, J.M.

2001-10-30

Because poly-L-lysine (PLL) can exist in the {alpha}-helix or {beta}-sheet conformation depending on solution preparation and solution conditions, PLL is a suitable candidate to probe the dependence of protein interactions on secondary structure. The osmotic second virial coefficient and weight-average molecular weight are reported from low-angle laser-light scattering measurements for PLL as a function of NaCl concentration, pH, and {alpha}-helix or {beta}-sheet content. Interactions between PLL molecules become more attractive as salt concentration increases due to screening of PLL charge by salt ions and at low salt concentration become more attractive as pH increases due to decreased net charge on PLL. The experimental results show that interactions are stronger for the {beta}-sheet conformation than for the {alpha}-helix conformation. A spherically-symmetric model for the potential of mean force is used to account for specific interactions not described by DLVO theory and to show how differences in secondary structure affect PLL interactions.

Antibacterial Activity of Silver Nanoparticles Synthesized by Using Extracts of Hedera helix

Directory of Open Access Journals (Sweden)

Ahmadreza Abbasifar

2017-01-01

Full Text Available Background Silver nanoparticles (AgNPs are one of the most widely applicable particles whose application is increasing in Nano world daily. Silver nanoparticles have expressed significant advances owing to wide range of applications in the field of bio-medical, sensors, antimicrobials, catalysts, electronics, optical fibers, agricultural, bio-labeling and the other areas. Green synthesis is the safe and easiest method of producing silver nanoparticles. Because of the production of the silver ions, silver nanoparticles are found to have the antibacterial activity. Objectives The aim of this study was to investigate antibacterial activity of silver nanoparticles synthesized by using extracts of Hedera helix against Bacillus subtilis and Klebsiella pneumoniae. Methods In this experimental study AgNPs were prepared by the reaction of 1mM silver nitrate and extracts of Hedera helix. Antibacterial activity of AgNPs was assessed by using disc diffusion method against Bacillus subtilis and Klebsiella pneumoniae. The AgNPs were characterized by UV-visible (vis spectrophotometer, particle size analyzer by dynamic light scattering (DLS method, transmission electron microscopy (TEM. Results AgNPs obtained showed significantly higher antimicrobial activities against B. subtilis and K. pneumonia in comparison to both AgNO3 and raw plant extracts. Conclusions Biological methods are a good competent for the chemical procedures, which are environment friendly and convenient.

Reticulate phylogeny of gastropod-shell-breeding cichlids from Lake Tanganyika – the result of repeated introgressive hybridization

Directory of Open Access Journals (Sweden)

Blanc Michel

2007-01-01

Full Text Available Abstract Background The tribe Lamprologini is the major substrate breeding lineage of Lake Tanganyika's cichlid species flock. Among several different life history strategies found in lamprologines, the adaptation to live and breed in empty gastropod shells is probably the most peculiar. Although shell-breeding arose several times in the evolutionary history of the lamprologines, all obligatory and most facultative shell-breeders belong to the so called "ossified group", a monophyletic lineage within the lamprologine cichlids. Since their distinctive life style enables these species to live and breed in closest vicinity, we hypothesized that these cichlids might be particularly prone to accidental hybridization, and that introgression might have affected the evolutionary history of this cichlid lineage. Results Our analyses revealed discrepancies between phylogenetic hypotheses based on mitochondrial and nuclear (AFLP data. While the nuclear phylogeny was congruent with morphological, behavioral and ecological characteristics, several species – usually highly specialized shell-breeders – were placed at contradicting positions in the mitochondrial phylogeny. The discordant phylogenies strongly suggest repeated incidents of introgressive hybridization between several distantly related shell-breeding species, which reticulated the phylogeny of this group of cichlids. Long interior branches and high bootstrap support for many interior nodes in the mitochondrial phylogeny argue against a major effect of ancient incomplete lineage sorting on the phylogenetic reconstruction. Moreover, we provide morphological and genetic (mtDNA and microsatellites evidence for ongoing hybridization among distantly related shell-breeders. In these cases, the territorial males of the inferred paternal species are too large to enter the shells of their mate, such that they have to release their sperm over the entrance of the shell to fertilize the eggs. With sperm

Characterizing Terrestrial Exoplanets

Science.gov (United States)

Meadows, V. S.; Lustig-Yaeger, J.; Lincowski, A.; Arney, G. N.; Robinson, T. D.; Schwieterman, E. W.; Deming, L. D.; Tovar, G.

2017-11-01

We will provide an overview of the measurements, techniques, and upcoming missions required to characterize terrestrial planet environments and evolution, and search for signs of habitability and life.

The Bacillus subtilis Conjugative Plasmid pLS20 Encodes Two Ribbon-Helix-Helix Type Auxiliary Relaxosome Proteins That Are Essential for Conjugation

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Andrés Miguel-Arribas

2017-11-01

Full Text Available Bacterial conjugation is the process by which a conjugative element (CE is transferred horizontally from a donor to a recipient cell via a connecting pore. One of the first steps in the conjugation process is the formation of a nucleoprotein complex at the origin of transfer (oriT, where one of the components of the nucleoprotein complex, the relaxase, introduces a site- and strand specific nick to initiate the transfer of a single DNA strand into the recipient cell. In most cases, the nucleoprotein complex involves, besides the relaxase, one or more additional proteins, named auxiliary proteins, which are encoded by the CE and/or the host. The conjugative plasmid pLS20 replicates in the Gram-positive Firmicute bacterium Bacillus subtilis. We have recently identified the relaxase gene and the oriT of pLS20, which are separated by a region of almost 1 kb. Here we show that this region contains two auxiliary genes that we name aux1LS20 and aux2LS20, and which we show are essential for conjugation. Both Aux1LS20 and Aux2LS20 are predicted to contain a Ribbon-Helix-Helix DNA binding motif near their N-terminus. Analyses of the purified proteins show that Aux1LS20 and Aux2LS20 form tetramers and hexamers in solution, respectively, and that they both bind preferentially to oriTLS20, although with different characteristics and specificities. In silico analyses revealed that genes encoding homologs of Aux1LS20 and/or Aux2LS20 are located upstream of almost 400 relaxase genes of the RelLS20 family (MOBL of relaxases. Thus, Aux1LS20 and Aux2LS20 of pLS20 constitute the founding member of the first two families of auxiliary proteins described for CEs of Gram-positive origin.

The Bacillus subtilis Conjugative Plasmid pLS20 Encodes Two Ribbon-Helix-Helix Type Auxiliary Relaxosome Proteins That Are Essential for Conjugation.

Science.gov (United States)

Miguel-Arribas, Andrés; Hao, Jian-An; Luque-Ortega, Juan R; Ramachandran, Gayetri; Val-Calvo, Jorge; Gago-Córdoba, César; González-Álvarez, Daniel; Abia, David; Alfonso, Carlos; Wu, Ling J; Meijer, Wilfried J J

2017-01-01

Bacterial conjugation is the process by which a conjugative element (CE) is transferred horizontally from a donor to a recipient cell via a connecting pore. One of the first steps in the conjugation process is the formation of a nucleoprotein complex at the origin of transfer ( oriT ), where one of the components of the nucleoprotein complex, the relaxase, introduces a site- and strand specific nick to initiate the transfer of a single DNA strand into the recipient cell. In most cases, the nucleoprotein complex involves, besides the relaxase, one or more additional proteins, named auxiliary proteins, which are encoded by the CE and/or the host. The conjugative plasmid pLS20 replicates in the Gram-positive Firmicute bacterium Bacillus subtilis . We have recently identified the relaxase gene and the oriT of pLS20, which are separated by a region of almost 1 kb. Here we show that this region contains two auxiliary genes that we name aux1 LS20 and aux2 LS20 , and which we show are essential for conjugation. Both Aux1 LS20 and Aux2 LS20 are predicted to contain a Ribbon-Helix-Helix DNA binding motif near their N-terminus. Analyses of the purified proteins show that Aux1 LS20 and Aux2 LS20 form tetramers and hexamers in solution, respectively, and that they both bind preferentially to oriT LS20 , although with different characteristics and specificities. In silico analyses revealed that genes encoding homologs of Aux1 LS20 and/or Aux2 LS20 are located upstream of almost 400 relaxase genes of the Rel LS20 family (MOB L ) of relaxases. Thus, Aux1 LS20 and Aux2 LS20 of pLS20 constitute the founding member of the first two families of auxiliary proteins described for CEs of Gram-positive origin.

Peptide-oligonucleotide conjugates as nanoscale building blocks for assembly of an artificial three-helix protein mimic

DEFF Research Database (Denmark)

Lou, Chenguang; Martos-Maldonado, Manuel C.; Madsen, Charlotte Stahl

2016-01-01

Peptide-based structures can be designed to yield artificial proteins with specific folding patterns and functions. Template-based assembly of peptide units is one design option, but the use of two orthogonal self-assembly principles, oligonucleotide triple helix and a coiled coil protein domain ...

MicroRNA-212 post-transcriptionally regulates oocyte-specific basic-helix-loop-helix transcription factor, factor in the germline alpha (FIGLA, during bovine early embryogenesis.

Directory of Open Access Journals (Sweden)

Swamy K Tripurani

Full Text Available Factor in the germline alpha (FIGLA is an oocyte-specific basic helix-loop-helix transcription factor essential for primordial follicle formation and expression of many genes required for folliculogenesis, fertilization and early embryonic survival. Here we report the characterization of bovine FIGLA gene and its regulation during early embryogenesis. Bovine FIGLA mRNA expression is restricted to gonads and is detected in fetal ovaries harvested as early as 90 days of gestation. FIGLA mRNA and protein are abundant in germinal vesicle and metaphase II stage oocytes, as well as in embryos from pronuclear to eight-cell stage but barely detectable at morula and blastocyst stages, suggesting that FIGLA might be a maternal effect gene. Recent studies in zebrafish and mice have highlighted the importance of non-coding small RNAs (microRNAs as key regulatory molecules targeting maternal mRNAs for degradation during embryonic development. We hypothesized that FIGLA, as a maternal transcript, is regulated by microRNAs during early embryogenesis. Computational predictions identified a potential microRNA recognition element (MRE for miR-212 in the 3' UTR of the bovine FIGLA mRNA. Bovine miR-212 is expressed in oocytes and tends to increase in four-cell and eight-cell stage embryos followed by a decline at morula and blastocyst stages. Transient transfection and reporter assays revealed that miR-212 represses the expression of FIGLA in a MRE dependent manner. In addition, ectopic expression of miR-212 mimic in bovine early embryos dramatically reduced the expression of FIGLA protein. Collectively, our results demonstrate that FIGLA is temporally regulated during bovine early embryogenesis and miR-212 is an important negative regulator of FIGLA during the maternal to zygotic transition in bovine embryos.

The poplar basic helix-loop-helix transcription factor BEE3 – Like gene affects biomass production by enhancing proliferation of xylem cells in poplar

Energy Technology Data Exchange (ETDEWEB)

Noh, Seol Ah, E-mail: s6022029@korea.ac.kr; Choi, Young-Im, E-mail: yichoi99@forest.go.kr; Cho, Jin-Seong, E-mail: jinsung3932@gmail.com; Lee, Hyoshin, E-mail: hslee@forest.go.kr

2015-06-19

Brassinosteroids (BRs) play important roles in many aspects of plant growth and development, including regulation of vascular cambium activities and cell elongation. BR-induced BEE3 (brassinosteroid enhanced expression 3) is required for a proper BR response. Here, we identified a poplar (Populus alba × Populus glandulosa) BEE3-like gene, PagBEE3L, encoding a putative basic helix-loop-helix (bHLH)-type transcription factor. Expression of PagBEE3L was induced by brassinolide (BL). Transcripts of PagBEE3L were mainly detected in stems, with the internode having a low level of transcription and the node having a relatively higher level. The function of the PagBEE3L gene was investigated through phenotypic analyses with PagBEE3L-overexpressing (ox) transgenic lines. This work particularly focused on a potential role of PagBEE3L in stem growth and development of polar. The PagBEE3L-ox poplar showed thicker and longer stems than wild-type plants. The xylem cells from the stems of PagBEE3L-ox plants revealed remarkably enhanced proliferation, resulting in an earlier thickening growth than wild-type plants. Therefore, this work suggests that xylem development of poplar is accelerated in PagBEE3L-ox plants and PagBEE3L plays a role in stem growth by increasing the proliferation of xylem cells to promote the initial thickening growth of poplar stems. - Highlights: • We identify the BEE3-like gene form hybrid poplar (Populus alba × Populus glandulosa). • We examine effects of overexpression of PagBEE3L on growth in poplar. • We found that 35S:BEE3L transgenic plants showed more rapid growth than wild-type plants. • BEE3L protein plays an important role in the development of plant stem.

The poplar basic helix-loop-helix transcription factor BEE3 – Like gene affects biomass production by enhancing proliferation of xylem cells in poplar

International Nuclear Information System (INIS)

Noh, Seol Ah; Choi, Young-Im; Cho, Jin-Seong; Lee, Hyoshin

2015-01-01

Brassinosteroids (BRs) play important roles in many aspects of plant growth and development, including regulation of vascular cambium activities and cell elongation. BR-induced BEE3 (brassinosteroid enhanced expression 3) is required for a proper BR response. Here, we identified a poplar (Populus alba × Populus glandulosa) BEE3-like gene, PagBEE3L, encoding a putative basic helix-loop-helix (bHLH)-type transcription factor. Expression of PagBEE3L was induced by brassinolide (BL). Transcripts of PagBEE3L were mainly detected in stems, with the internode having a low level of transcription and the node having a relatively higher level. The function of the PagBEE3L gene was investigated through phenotypic analyses with PagBEE3L-overexpressing (ox) transgenic lines. This work particularly focused on a potential role of PagBEE3L in stem growth and development of polar. The PagBEE3L-ox poplar showed thicker and longer stems than wild-type plants. The xylem cells from the stems of PagBEE3L-ox plants revealed remarkably enhanced proliferation, resulting in an earlier thickening growth than wild-type plants. Therefore, this work suggests that xylem development of poplar is accelerated in PagBEE3L-ox plants and PagBEE3L plays a role in stem growth by increasing the proliferation of xylem cells to promote the initial thickening growth of poplar stems. - Highlights: • We identify the BEE3-like gene form hybrid poplar (Populus alba × Populus glandulosa). • We examine effects of overexpression of PagBEE3L on growth in poplar. • We found that 35S:BEE3L transgenic plants showed more rapid growth than wild-type plants. • BEE3L protein plays an important role in the development of plant stem

Green Fluorescence of Cytaeis Hydroids Living in Association with Nassarius Gastropods in the Red Sea

KAUST Repository

Prudkovsky, Andrey A.; Ivanenko, Viatcheslav N.; Nikitin, Mikhail A.; Lukyanov, Konstantin A.; Belousova, Anna; Reimer, James D.; Berumen, Michael L.

2016-01-01

Green Fluorescent Proteins (GFPs) have been reported from a wide diversity of medusae, but only a few observations of green fluorescence have been reported for hydroid colonies. In this study, we report on fluorescence displayed by hydroid polyps of the genus Cytaeis Eschscholtz, 1829 (Hydrozoa: Anthoathecata: Filifera) found at night time in the southern Red Sea (Saudi Arabia) living on shells of the gastropod Nassarius margaritifer (Dunker, 1847) (Neogastropoda: Buccinoidea: Nassariidae). We examined the fluorescence of these polyps and compare with previously reported data. Intensive green fluorescence with a spectral peak at 518 nm was detected in the hypostome of the Cytaeis polyps, unlike in previous reports that reported fluorescence either in the basal parts of polyps or in other locations on hydroid colonies. These results suggest that fluorescence may be widespread not only in medusae, but also in polyps, and also suggests that the patterns of fluorescence localization can vary in closely related species. The fluorescence of polyps may be potentially useful for field identification of cryptic species and study of geographical distributions of such hydroids and their hosts.

Green Fluorescence of Cytaeis Hydroids Living in Association with Nassarius Gastropods in the Red Sea

KAUST Repository

Prudkovsky, Andrey A.

2016-02-03

Green Fluorescent Proteins (GFPs) have been reported from a wide diversity of medusae, but only a few observations of green fluorescence have been reported for hydroid colonies. In this study, we report on fluorescence displayed by hydroid polyps of the genus Cytaeis Eschscholtz, 1829 (Hydrozoa: Anthoathecata: Filifera) found at night time in the southern Red Sea (Saudi Arabia) living on shells of the gastropod Nassarius margaritifer (Dunker, 1847) (Neogastropoda: Buccinoidea: Nassariidae). We examined the fluorescence of these polyps and compare with previously reported data. Intensive green fluorescence with a spectral peak at 518 nm was detected in the hypostome of the Cytaeis polyps, unlike in previous reports that reported fluorescence either in the basal parts of polyps or in other locations on hydroid colonies. These results suggest that fluorescence may be widespread not only in medusae, but also in polyps, and also suggests that the patterns of fluorescence localization can vary in closely related species. The fluorescence of polyps may be potentially useful for field identification of cryptic species and study of geographical distributions of such hydroids and their hosts.

Analysis of α-helix unfolding in the pine nut peptide Lys-Cys-His-Lys-Pro induced by pulsed electric field.

Science.gov (United States)

Xing, Jie; Zhang, Sitian; Zhang, Mingdi; Lin, Songyi

2017-09-01

A variety of analytical techniques were applied to explore the effects of pulsed electric field (PEF) on α-helix structural changes in the novel antioxidant peptide Lys-Cys-His-Lys-Pro (KCHKP, 611.76 Da). The relative α-helix content of the KCHKP peptide was significantly altered from 100% to 89.91 ± 0.97% when the electric pulse frequency was 1800 Hz and the field intensity was 10 kV cm -1 . Moreover, the 1,1-diphenyl-2-pycryl-hydrazyl (DPPH) and 2,2-azinobis diammonium salt (ABTS) radical-scavenging activities of PEF-treated KCHKP were increased from 56.31% ± 0.74% to 84.33% ± 1.23% and from 40.56% ± 0.78% to 51.33% ± 0.27%, respectively. PEF treatment increased peptide linkage stretch vibration and altered hydrogen bonding of KCHKP. The stability of the α-helix structure was influenced by hydrogen bonds within the peptide linkage of KCHKP induced by PEF and was related to changes in antioxidant activity. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Estudio del hepatopáncreas de Helix Aspersa en situación normal y tras ayuno

OpenAIRE

Almendros Gallego, Antonio Manuel

2013-01-01

Se hace un estudio a microscopia electrónica de los diversos tipos celulares que componen el hepatopancreas de Helix Aspersa atendiendo a los componentes celulares característicos de cada uno de ellos tanto en situación normal como a diversos periodos de ayuno

Commercialization of terrestrial applications of aerospace power technology

International Nuclear Information System (INIS)

Landsberg, D.R.

1992-01-01

The potential for commercialization of terrestrial energy systems based upon aerospace power technology's explored. Threats to the aerospace power technology industry, caused by the end of the cold war and weak world economy are described. There are also new opportunities caused by increasing terrestrial energy needs and world-wide concern for the environment. In this paper, the strengths and weaknesses of the aerospace power industry in commercializing terrestrial energy technologies are reviewed. Finally, actions which will enable the aerospace power technology industry to commercialize products into terrestrial energy markets are described

[Composition, distribution and abundance of gastropod larvae in the South of Quintana Roo,Mexico and north of Belice].

Science.gov (United States)

Oliva Rivera, J; de Jesús Navarrete, A

2000-12-01

To know the composition, abundance and distribution of gastropod larvae, monthly samplings were carried out in the south of Quintana Roo, Mexico and north of Belize, from April to December, 1996. Collections were made in six sites at Chinchorro Bank, four in the South Coast and six at Hol-Chan, Belize, between the 10 and 20 hrs. At each station 2.5 m3 of seawater were pumped through a 202 microns mesh; 27 species were identified. The most abundant species were: South Coast, Rissoina sp. 1., Limacina sp. 1 and Natica sp. 1, Chinchorro Bank, Limacina sp. 1, Creseis acicula, Cerithiopsis hero and Rissoina sp. 1 and Hol-Chan, Limacina sp. 2, Alaba incerta and Rissoina sp. 1. The highest abundance was in rainy season. Apparently the presence of winds, coastal currents and food availability, control the distribution and abundance of larvae.

Performance of Process Damping in Machining Titanium Alloys at Low Cutting Speed with Different Helix Tools

International Nuclear Information System (INIS)

Shaharun, M A; Yusoff, A R; Reza, M S; Jalal, K A

2012-01-01

Titanium is a strong, lustrous, corrosion-resistant and transition metal with a silver color to produce strong lightweight alloys for industrial process, automotive, medical instruments and other applications. However, it is very difficult to machine the titanium due to its poor machinability. When machining titanium alloys with the conventional tools, the wear rate of the tool is rapidly accelerate and it is generally difficult to achieve at high cutting speed. In order to get better understanding of machining titanium alloy, the interaction between machining structural system and the cutting process which result in machining instability will be studied. Process damping is a useful phenomenon that can be exploited to improve the limited productivity of low speed machining. In this study, experiments are performed to evaluate the performance of process damping of milling under different tool helix geometries. The results showed that the helix of 42° angle is significantly increase process damping performance in machining titanium alloy.

Right- and left-handed three-helix proteins. II. Similarity and differences in mechanical unfolding of proteins.

Science.gov (United States)

Glyakina, Anna V; Likhachev, Ilya V; Balabaev, Nikolay K; Galzitskaya, Oxana V

2014-01-01

Here, we study mechanical properties of eight 3-helix proteins (four right-handed and four left-handed ones), which are similar in size under stretching at a constant speed and at a constant force on the atomic level using molecular dynamics simulations. The analysis of 256 trajectories from molecular dynamics simulations with explicit water showed that the right-handed three-helix domains are more mechanically resistant than the left-handed domains. Such results are observed at different extension velocities studied (192 trajectories obtained at the following conditions: v = 0.1, 0.05, and 0.01 Å ps(-1) , T = 300 K) and under constant stretching force (64 trajectories, F = 800 pN, T = 300 K). We can explain this by the fact, at least in part, that the right-handed domains have a larger number of contacts per residue and the radius of cross section than the left-handed domains. Copyright © 2013 Wiley Periodicals, Inc.

Conservation of a helix-stabilizing dipole moment in the PP-fold family of regulatory peptides

DEFF Research Database (Denmark)

Bjørnholm, B; Jørgensen, Flemming Steen; Schwartz, T W

1993-01-01

arrangement were performed in two ways: (1) by the use of a Poisson-Boltzmann approach which allows for an estimate of the screening effect, and (2) by the use of a uniform dielectric model (Coulomb's law). It is found that the alpha-helix is stabilized by approximately 5-10 kcal/mol due to electrostatic...

Terrestrial carbohydrates support freshwater zooplankton during phytoplankton deficiency.

Science.gov (United States)

Taipale, Sami J; Galloway, Aaron W E; Aalto, Sanni L; Kahilainen, Kimmo K; Strandberg, Ursula; Kankaala, Paula

2016-08-11

Freshwater food webs can be partly supported by terrestrial primary production, often deriving from plant litter of surrounding catchment vegetation. Although consisting mainly of poorly bioavailable lignin, with low protein and lipid content, the carbohydrates from fallen tree leaves and shoreline vegetation may be utilized by aquatic consumers. Here we show that during phytoplankton deficiency, zooplankton (Daphnia magna) can benefit from terrestrial particulate organic matter by using terrestrial-origin carbohydrates for energy and sparing essential fatty acids and amino acids for somatic growth and reproduction. Assimilated terrestrial-origin fatty acids from shoreline reed particles exceeded available diet, indicating that Daphnia may convert a part of their dietary carbohydrates to saturated fatty acids. This conversion was not observed with birch leaf diets, which had lower carbohydrate content. Subsequent analysis of 21 boreal and subarctic lakes showed that diet of herbivorous zooplankton is mainly based on high-quality phytoplankton rich in essential polyunsaturated fatty acids. The proportion of low-quality diets (bacteria and terrestrial particulate organic matter) was <28% of the assimilated carbon. Taken collectively, the incorporation of terrestrial carbon into zooplankton was not directly related to the concentration of terrestrial organic matter in experiments or lakes, but rather to the low availability of phytoplankton.

A magnetic torsional wave near the Galactic Centre traced by a 'double helix' nebula.

Science.gov (United States)

Morris, Mark; Uchida, Keven; Do, Tuan

2006-03-16

The magnetic field in the central few hundred parsecs of the Milky Way has a dipolar geometry and is substantially stronger than elsewhere in the Galaxy, with estimates ranging up to a milligauss (refs 1-6). Characterization of the magnetic field at the Galactic Centre is important because it can affect the orbits of molecular clouds by exerting a drag on them, inhibit star formation, and could guide a wind of hot gas or cosmic rays away from the central region. Here we report observations of an infrared nebula having the morphology of an intertwined double helix about 100 parsecs from the Galaxy's dynamical centre, with its axis oriented perpendicular to the Galactic plane. The observed segment is about 25 parsecs in length, and contains about 1.25 full turns of each of the two continuous, helically wound strands. We interpret this feature as a torsional Alfvén wave propagating vertically away from the Galactic disk, driven by rotation of the magnetized circumnuclear gas disk. The direct connection between the circumnuclear disk and the double helix is ambiguous, but the images show a possible meandering channel that warrants further investigation.

Louisiana ESI: T_MAMMAL (Terrestrial Mammal Polygons)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for terrestrial mammals in Louisiana. Vector polygons in this data set represent terrestrial mammal...

Assembly of Liposomes Controlled by Triple Helix Formation

DEFF Research Database (Denmark)

Vogel, Stefan; Jakobsen, Ulla

2013-01-01

Attachment of DNA to the surface of different solid nanoparticles (e.g. gold- and silica nanoparticles) is well established and a number of DNA-modified solid nanoparticle systems have been applied to thermal denaturation analysis of oligonucleotides. We report herein the non-covalent immobilizat...... analysis (NTA) and dynamic light scattering (DLS) show independently from ultraviolet spectroscopy experiments the formation of liposome aggregates.......-covalent immobilization of oligonucleotides on the surface of soft nanoparticles (e.g. liposomes) and the subsequent controlled assembly by DNA triple helix formation. The non-covalent approach avoids tedious surface chemistry and necessary purification procedures and can simplify and extend the available methodology...... sequences (G or C-rich) to explore the applicability of the method for different triple helical assembly modes. We demonstrate advantages and limitations of the approach and proof the reversible and reproducible formation of liposome aggregates during thermal denaturation cycles. Nanoparticle tracking...

Linking animals aloft with the terrestrial landscape

Science.gov (United States)

Buler, Jeffrey J.; Barrow, Wylie; Boone, Matthew; Dawson, Deanna K.; Diehl, Robert H.; Moore, Frank R.; Randall, Lori A.; Schreckengost, Timothy; Smolinsky, Jaclyn A.

2018-01-01

Despite using the aerosphere for many facets of their life, most flying animals (i.e., birds, bats, some insects) are still bound to terrestrial habitats for resting, feeding, and reproduction. Comprehensive broad-scale observations by weather surveillance radars of animals as they leave terrestrial habitats for migration or feeding flights can be used to map their terrestrial distributions either as point locations (e.g., communal roosts) or as continuous surface layers (e.g., animal densities in habitats across a landscape). We discuss some of the technical challenges to reducing measurement biases related to how radars sample the aerosphere and the flight behavior of animals. We highlight a recently developed methodological approach that precisely and quantitatively links the horizontal spatial structure of birds aloft to their terrestrial distributions and provides novel insights into avian ecology and conservation across broad landscapes. Specifically, we present case studies that (1) elucidate how migrating birds contend with crossing ecological barriers and extreme weather events, (2) identify important stopover areas and habitat use patterns of birds along their migration routes, and (3) assess waterfowl response to wetland habitat management and restoration. These studies aid our understanding of how anthropogenic modification of the terrestrial landscape (e.g., urbanization, habitat management), natural geographic features, and weather (e.g., hurricanes) can affect the terrestrial distributions of flying animals.

Modified Quad Helix for Correction of Severely Rotated Incisors in Cleft Cases

Directory of Open Access Journals (Sweden)

Aneesha Ashok Shetty

2014-01-01

Full Text Available Clefts of the lip, alveolus and/or palate are often associated with several dental anomalies, the most common of which are severely rotated maxillary incisors. Patients with such congenital deformities seek orthodontic treatment as early as possible, for an esthetic as well as psychosocial benefit. Here, a new clinical technique is demonstrated for correction of a severely rotated maxillary central incisor which can be carried out in the mixed dentition phase itself, by modifying a commonly used palatal expansion appliance: the quad helix.

Lipid-mediated interactions tune the association of glycophorin A helix and its disruptive mutants in membranes

NARCIS (Netherlands)

Sengupta, Durba; Marrink, Siewert J.

2010-01-01

The specific and non-specific driving forces of helix association within membranes are still poorly understood. Here, we use coarse-grain molecular dynamics simulations to study the association behavior of glycophorin A and two disruptive mutants, T87F and a triple mutant of the GxxxG motif

Preparation and evaluation of appertized from snail Helix aspersa M

Directory of Open Access Journals (Sweden)

Nelson Loyola López

2015-01-01

Full Text Available This study includes the development and evaluation of snails (Helix aspersa M. appertized, collected at a heliciculture breeding center, located in Los Niches sector, Curico, Maule region, South-central of Chile. The test was conducted at the Laboratory of Sciences of the Catholic University of Maule, Nuestra Señora del Carmen Campus, Curico. The main objective of this work was to study the influence of appertized on sensory attributes and commercial durability of snail Helix aspersa M. Additionally, some specific objectives were proposed as follow: to provide this mollusc with a commercial alternative for it consume, to evaluate its organoleptic characteristics and guarantee the product from both the microbiological and nutritional points of view. Three media cover were used (T0: water + NaCl 2%; T1: Water + NaCl 2% + citric acid 0.5% + kilol and T2: extra virgin olive oil + spices + tocopherol. The product was assessed at two different times, after 30 and 90 days of storage. Two sensory evaluations were conducted to measure various organoleptic attributes and acceptability of the appertized by 14 trained panelists. Amino acid, vitamins, cholesterol, acidity, heavy metals, phosphorus and organochlorines analysis were performed. The presence of both total and fecal contaminant microorganisms was determined. Attributes such as color, flavor, aroma, texture and overall acceptability were also measured. Preserves made by T0 and T1 treatments were equally accepted by the panelists. However, preserve from treatment T2 was rejected because of the detection in them of a very dark color, odor and mealy texture. Positive results regarding the content of amino acids, vitamin C and low cholesterol, as well as the absence of pathogenic microorganisms were obtained for the three treatments.

The decadal state of the terrestrial carbon cycle : Global retrievals of terrestrial carbon allocation, pools, and residence times

NARCIS (Netherlands)

Bloom, A Anthony; Exbrayat, Jean-François; van der Velde, Ivar R; Feng, Liang; Williams, Mathew

2016-01-01

The terrestrial carbon cycle is currently the least constrained component of the global carbon budget. Large uncertainties stem from a poor understanding of plant carbon allocation, stocks, residence times, and carbon use efficiency. Imposing observational constraints on the terrestrial carbon cycle

Cryptic diversity in Mediterranean gastropods of the genus Aplus (Neogastropoda: Buccinidae

Directory of Open Access Journals (Sweden)

Chrifa Aissaoui

2016-11-01

Full Text Available Northeastern Atlantic and Mediterranean gastropods previously ascribed to the buccinid genus Pollia Gray, 1837 are more correctly classified in the genus Aplus de Gregorio, 1885. Using an integrative taxonomy approach combining molecular, morphological and geographic data, we revisit the limits of the extant species in the area, and propose a molecular phylogenetic hypothesis based on 66 specimens from various localities in the Mediterranean Sea, including type localities of some nominal taxa. We used a preliminary morphological inspection, followed by a DNA-barcoding approach to propose species hypotheses, subsequently consolidated using additional data (phylogenetic, geographic and refined morphological data. Seven species hypotheses were eventually retained within our molecularly assayed samples, versus three classical morphologically recognized species. Among these, three correspond to Aplus dorbignyi (Payreaudeau, 1826 with its hitherto unrecognized geographical cognates A. gaillardoti (Puton, 1856 (eastern Mediterranean and Aplus nodulosus (Bivona Ant., 1832 (Sicily; two closely related, yet considerably divergent, lineages are treated as a single species under Aplus scaber (Locard, 1892; the classically admitted Aplus scacchianus (Philippi, 1844 is confirmed by molecular evidence; Mediterranean populations attributable to Aplus assimilis (Reeve, 1846 may represent either cryptic native populations or an ongoing invasion of the Mediterranean by what was hitherto considered to be a West African species; finally, specimens from the Strait of Gibraltar may represent an undescribed species, but we conservatively refrain from formally introducing it pending the analysis of more material, and it is compared with the similar Aplus campisii (Ardovini, 2014, recently described from Sicily and not assayed molecularly, and Aplus scaber.

Coherent helix vacancy phonon and its ultrafast dynamics waning in topological Dirac semimetal C d3A s2

Science.gov (United States)

Sun, Fei; Wu, Q.; Wu, Y. L.; Zhao, H.; Yi, C. J.; Tian, Y. C.; Liu, H. W.; Shi, Y. G.; Ding, H.; Dai, X.; Richard, P.; Zhao, Jimin

2017-06-01

We report an ultrafast lattice dynamics investigation of the topological Dirac semimetal C d3A s2 . A coherent phonon beating among three evenly spaced A1 g optical phonon modes (of frequencies 1.80, 1.96, and 2.11 THz, respectively) is unambiguously observed. The two side modes originate from the counter helixes composing Cd vacancies. Significantly, such helix vacancy-induced phonon (HVP) modes experience prominent extra waning in their ultrafast dynamics as temperature increases, which is immune to the central mode. Above 200 K, the HVP becomes inactive, which may potentially affect the topological properties. Our results in the lattice degree of freedom suggest the indispensable role of temperature in considering topological properties of such quantum materials.

PH4 of petunia is an R2R3-MYB protein that activates vacuolar acidification through interactions with Basic-Helix-Loop transcription factors of the anthocyanin pathway.

NARCIS (Netherlands)

Quattrocchio, F.M.; Verweij, C.W.; Kroon, A.R.; Spelt, C.E.; Mol, J.N.M.; Koes, R.E.

2006-01-01

The Petunia hybrids genes ANTHOCYANIN1 (AN1) and AN2 encode transcription factors with a basic-helix-loop-helix (BHLH) and a MYB domain, respectively, that are required for anthocyanin synthesis and acidification of the vacuole in petal cells. Mutation of PH4 results in a bluer flower color,

Behavioural modification of the optic tentacle of Helix pom atia; effect of puromycin, activity of S-100

DEFF Research Database (Denmark)

Christoffersen, Gert Rene Juul; Frederiksen, K; Johansen, Jørgen

1981-01-01

1. 1. A long-term learning phenomenon in the tentacle of Helix pomatia has been observed.   2. 2. Repeated mechanical stimulation of the optic tentacle led to habituation of the associated withdrawal-extension action pattern whereas repeated combined mechanical and electrical stimulation potentia...

Circularly Polarized Planar Helix Phased Antenna Array for 5G Mobile Terminals

DEFF Research Database (Denmark)

Syrytsin, Igor A.; Zhang, Shuai; Pedersen, Gert F.

2017-01-01

In this paper, a planar helix mobile phased antenna array is proposed for 5th generation communication systems with operating frequency of 28GHz. The proposed array displays circular polarization in the endfire direction. Over 65 degrees of axial ratio beamwidth and 7GHz of axial ratio bandwidth...... has been achieved in the proposed design. The coverage performance of the proposed phased antenna array has also been studied by using the coverage efficiency metric. Coverage efficiency of 50 % at 5 dBi gain is achieved by the proposed phased mobile antenna array....

Sex ratio variation in the bumblebee Bombus terrestris

DEFF Research Database (Denmark)

Duchateau, Marie José; Velthuis, Hayo H. W.; Boomsma, Jacobus Jan

2004-01-01

Bombus terrestris, bumblebees, colony development, queen control, reproductive strategies, sex allocation......Bombus terrestris, bumblebees, colony development, queen control, reproductive strategies, sex allocation...

The Circumpolar Biodiversity Monitoring Program Terrestrial Plan

DEFF Research Database (Denmark)

Christensen, Tom; Payne, J.; Doyle, M.

, understand and report on long-term change in Arctic terrestrial ecosystems and biodiversity, and to identify knowledge gaps and priorities. This poster will outline the key management questions the plan aims to address and the proposed nested, multi-scaled approach linking targeted, research based monitoring...... and coastal environments. The CBMP Terrestrial Plan is a framework to focus and coordinate monitoring of terrestrial biodiversity across the Arctic. The goal of the plan is to improve the collective ability of Arctic traditional knowledge (TK) holders, northern communities, and scientists to detect...

Terrestrial nitrogen-carbon cycle interactions at the global scale.

Science.gov (United States)

Zaehle, S

2013-07-05

Interactions between the terrestrial nitrogen (N) and carbon (C) cycles shape the response of ecosystems to global change. However, the global distribution of nitrogen availability and its importance in global biogeochemistry and biogeochemical interactions with the climate system remain uncertain. Based on projections of a terrestrial biosphere model scaling ecological understanding of nitrogen-carbon cycle interactions to global scales, anthropogenic nitrogen additions since 1860 are estimated to have enriched the terrestrial biosphere by 1.3 Pg N, supporting the sequestration of 11.2 Pg C. Over the same time period, CO2 fertilization has increased terrestrial carbon storage by 134.0 Pg C, increasing the terrestrial nitrogen stock by 1.2 Pg N. In 2001-2010, terrestrial ecosystems sequestered an estimated total of 27 Tg N yr(-1) (1.9 Pg C yr(-1)), of which 10 Tg N yr(-1) (0.2 Pg C yr(-1)) are due to anthropogenic nitrogen deposition. Nitrogen availability already limits terrestrial carbon sequestration in the boreal and temperate zone, and will constrain future carbon sequestration in response to CO2 fertilization (regionally by up to 70% compared with an estimate without considering nitrogen-carbon interactions). This reduced terrestrial carbon uptake will probably dominate the role of the terrestrial nitrogen cycle in the climate system, as it accelerates the accumulation of anthropogenic CO2 in the atmosphere. However, increases of N2O emissions owing to anthropogenic nitrogen and climate change (at a rate of approx. 0.5 Tg N yr(-1) per 1°C degree climate warming) will add an important long-term climate forcing.

Pseudouridylation of helix 69 of 23S rRNA is necessary for an effective translation termination

DEFF Research Database (Denmark)

Ejby, Morten; Sørensen, Michael A; Pedersen, Steen

2007-01-01

Escherichia coli strains with inactivated rluD genes were previously found to lack the conserved pseudouridines in helix 69 of 23S ribosomal RNA and to grow slowly. A suppressor mutant was isolated with a near normal growth rate that had changed the conserved Glu-172 codon to a Lys codon in prf...

A Grounded Theory for Regional Development through the IT Offshoring Industry with the Triple-Helix Involvment

Science.gov (United States)

Villarreal de la Garza, Sonia

2011-01-01

The purpose of this qualitative grounded study was to explore the thoughts, experiences, and needs of potential clients and of the triple-helix members with the intention to establish a framework to support the development of the regional economy through the information technology (IT) and business processing outsourcing (BPO) offshoring industry.…

Ontogenetic shifts in terrestrial reliance of stream-dwelling brown trout

Directory of Open Access Journals (Sweden)

Javier Sánchez-Hernández

2016-07-01

Full Text Available This study focuses on terrestrial reliance of brown trout (Salmo trutta and compared it to the potential prey available (macrozoobenthos and drifting invertebrates in three temperate rivers (Galicia, NW Spain, with special emphasis on variations in terrestrial energy intake through the ontogeny of brown trout. Additionally, we paid particular attention to individual variation of terrestrial resource use within and between age classes. Prey items were grouped in four categories: i aquatic invertebrates; ii imagoes of aquatic invertebrates; iii terrestrial invertebrates; and iv fish prey. Next, energy composition was measured according to dry weight-energy equations for each individual in line with above-mentioned prey categories. Our findings illustrate that terrestrial invertebrates appeared to be scarce in the environment, whereas aquatic food resources were rather abundant and accessible. The use of terrestrial invertebrates tended to increase with age, but with a high degree of inter-individual variation in resource use. In fact, the individual reliance of brown trout on terrestrial invertebrates may vary considerably (between 0% and 76.9%. Besides, the frequency of terrestrial foragers, i.e., individuals with terrestrial invertebrates in their stomachs, increased with age, except in one population which had the maximum value in the age-2 class. The acquisition of terrestrial invertebrates thus appears to be a process strongly dependent upon the actual food availability in the environment, but with a high degree of individual variance in resource use within the same age class. Finally, we discuss that terrestrial invertebrates may largely contribute to cover the energy intake of the species, highlighting the interface between terrestrial and aquatic ecosystems, and thereby the importance of riparian canopy cover as a key factor for food supply of stream-dwelling salmonids species.

Priapism caused by 'Tribulus terrestris'.

Science.gov (United States)

Campanelli, M; De Thomasis, R; Tenaglia, R L

2016-01-01

A 36-year-old Caucasian man was diagnosed with a 72-h-lasting priapism that occurred after the assumption of a Herbal supplement based on Tribulus terrestris, which is becoming increasingly popular for the treatment of sexual dysfunction. The patient underwent a cavernoglandular shunt (Ebbehoj shunt) in order to obtain complete detumescence, from which derived negative post-episode outcomes on sexual function. All patients consuming non-FDA-approved alternative supplements such as Tribulus terrestris should be warned about the possible serious side effects.

An evolutionary triple helix to strengthen energy regulation: Implications for management

Energy Technology Data Exchange (ETDEWEB)

Rizzi, Francesco; Borzoni, Matteo

2010-09-15

Regulation is the basic tool to implement energy policy. The evolution of the regulation is influenced by its impacts on the industrial activities. Consequently, entrepreneurs acts in a continuously adapting-by-interacting environment. Both from a systemic and an atomistic perspective, this paper provides a theoretical framework for energy regulation development in order to support management implications. This work builds on the triple helix model and extends it to energy regulation development processes. It concludes that the analysis of intangible resources and their related services at inter-organizational level is fundamental to guide companies in designing win-win corporate strategies and in their operazionalization.

Durable terrestrial bedrock predicts submarine canyon formation

Science.gov (United States)

Smith, Elliot; Finnegan, Noah J.; Mueller, Erich R.; Best, Rebecca J.

2017-01-01

Though submarine canyons are first-order topographic features of Earth, the processes responsible for their occurrence remain poorly understood. Potentially analogous studies of terrestrial rivers show that the flux and caliber of transported bedload are significant controls on bedrock incision. Here we hypothesize that coarse sediment load could exert a similar role in the formation of submarine canyons. We conducted a comprehensive empirical analysis of canyon occurrence along the West Coast of the contiguous United States which indicates that submarine canyon occurrence is best predicted by the occurrence of durable crystalline bedrock in adjacent terrestrial catchments. Canyon occurrence is also predicted by the flux of bed sediment to shore from terrestrial streams. Surprisingly, no significant correlation was observed between canyon occurrence and the slope or width of the continental shelf. These findings suggest that canyon incision is promoted by greater yields of durable terrestrial clasts to the shore.

A double-helix and cross-patterned solenoid used as a wirelessly powered receiver for medical implants

Science.gov (United States)

Mao, Shitong; Wang, Hao; Mao, Zhi-Hong; Sun, Mingui

2018-05-01

Many medical implants need to be designed in the shape of a cylinder (rod), a cuboid or a capsule in order to adapt to a specific site within the human body or facilitate the implantation procedure. In order to wirelessly power these types of implants, a pair of coils, one is located inside the human body and one is outside, is often used. Since most organs such as major muscles, blood vessels, and nerve bundles are anatomically parallel to the body surface, the most desired wireless power transfer (WPT) direction is from the external power transmission pad (a planar coil) to the lateral surface of the implant. However, to obtain optimal coupling, the currently used solenoid coil requires being positioned perpendicular to the body surface, which is often medically or anatomically unacceptable. In this research, a concentric double-helix (DH) coil with an air core is presented for use in implantable devices. Two helical coils are tilted at opposite angles (±45 degrees) to form a cross pattern. The WPT system is designed using the magnetic resonance concept for wireless power transfer (MR-WPT). The power transfer efficiency (PTE) relies on the near-field magnetic coupling which is closely related to the location and orientation of the DH coil. We explain how the novel structure of the DH solenoid magnifies the mutual inductance with the widely adopted circular planner coil and how the PTE is improved in comparison to the case of the conventional solenoid coil. We also study an important case where the double-helix power reception coil is laterally and angularly misaligned with the transmitter. Finally, our computational study using the finite element method and experimental study with actually constructed prototypes are presented which have proven our new double-helix coil design.

A double-helix and cross-patterned solenoid used as a wirelessly powered receiver for medical implants

Directory of Open Access Journals (Sweden)

Shitong Mao

2018-05-01

Full Text Available Many medical implants need to be designed in the shape of a cylinder (rod, a cuboid or a capsule in order to adapt to a specific site within the human body or facilitate the implantation procedure. In order to wirelessly power these types of implants, a pair of coils, one is located inside the human body and one is outside, is often used. Since most organs such as major muscles, blood vessels, and nerve bundles are anatomically parallel to the body surface, the most desired wireless power transfer (WPT direction is from the external power transmission pad (a planar coil to the lateral surface of the implant. However, to obtain optimal coupling, the currently used solenoid coil requires being positioned perpendicular to the body surface, which is often medically or anatomically unacceptable. In this research, a concentric double-helix (DH coil with an air core is presented for use in implantable devices. Two helical coils are tilted at opposite angles (±45 degrees to form a cross pattern. The WPT system is designed using the magnetic resonance concept for wireless power transfer (MR-WPT. The power transfer efficiency (PTE relies on the near-field magnetic coupling which is closely related to the location and orientation of the DH coil. We explain how the novel structure of the DH solenoid magnifies the mutual inductance with the widely adopted circular planner coil and how the PTE is improved in comparison to the case of the conventional solenoid coil. We also study an important case where the double-helix power reception coil is laterally and angularly misaligned with the transmitter. Finally, our computational study using the finite element method and experimental study with actually constructed prototypes are presented which have proven our new double-helix coil design.

Tribulus terrestris Extract Improves Human Sperm Parameters In Vitro

Science.gov (United States)

Khaleghi, Sara; Bakhtiari, Mitra; Asadmobini, Atefeh; Esmaeili, Farzane

2016-01-01

Objective. The object of present study was to investigate the effects of direct addition of Tribulus terrestris extract on human sperm parameters. Design. Semen specimens from 40 healthy men volunteers were divided into 4 groups: one group received no treatment (control group) while the others were incubated with 20, 40, and 50 µg/mL of T terrestris extract (experimental groups). Motility, viability, and DNA fragmentation were assessed in all groups. Results. The incubation of human semen with 40 and 50 μg/mL of T terrestris extract significantly enhanced total sperm motility, number of progressive motile spermatozoa, and curvilinear velocity over 60 to 120 minutes’ holding time (P terrestris extract (P terrestris extract to human sperm could affect male fertility capacity. PMID:27694560

Tribulus terrestris Extract Improves Human Sperm Parameters In Vitro.

Science.gov (United States)

Khaleghi, Sara; Bakhtiari, Mitra; Asadmobini, Atefeh; Esmaeili, Farzane

2016-09-30

The object of present study was to investigate the effects of direct addition of Tribulus terrestris extract on human sperm parameters. Semen specimens from 40 healthy men volunteers were divided into 4 groups: one group received no treatment (control group) while the others were incubated with 20, 40, and 50 µg/mL of T terrestris extract (experimental groups). Motility, viability, and DNA fragmentation were assessed in all groups. The incubation of human semen with 40 and 50 μg/mL of T terrestris extract significantly enhanced total sperm motility, number of progressive motile spermatozoa, and curvilinear velocity over 60 to 120 minutes' holding time (P terrestris extract (P terrestris extract to human sperm could affect male fertility capacity. © The Author(s) 2016.

Intracapsular development and dispersal polymorphism in the predatory gastropod Ocenebra erinaceus (Linnaeus 1758)

Science.gov (United States)

Smith, Kathryn E.; Reed, Adam J.; Thatje, Sven

2015-09-01

Intraspecific polymorphism during development, such as poecilogony or dispersal polymorphism, has rarely been observed in the marine environment. The ecological advantages of this bet-hedging strategy, whereby the offspring from one species exhibit multiple developmental modes, include the potential for rapid colonization of new habitats while simultaneously achieving a degree of gene flow between populations. The muricid gastropod, Ocenebra erinaceus, is a common, shallow-water marine predator found across England and France. Historically, O. erinaceus caused significant damage to shellfisheries, but more recently it has been impacted by TBT-induced imposex. Despite the previous attention given to this species, little is known about its encapsulated development. Studying O. erinaceus egg capsules from the Solent, UK, we describe intracapsular development at 15 °C, the in situ temperature at time of oviposition. Within each capsule, all embryos developed; no nurse eggs were present. Development was categorized into eight ontogenetic stages, although not all individuals displayed every stage; embryos hatched as either swimming late-pediveliger larvae or crawling juveniles after 59-69 days, indicating dispersal polymorphism to occur in this species. Swimming late-pediveliger larvae completed metamorphosis within 72 h of hatching. As O. erinaceus continues to recover from TBT pollution, dispersal polymorphism may facilitate a rapid expansion in both population size and range. If this occurs, O. erinaceus has the potential to, once again, become a serious problem for shellfisheries around Europe.

Spawn in two deep-sea volute gastropods (Neogastropoda: Volutidae) from southwestern Atlantic waters

Science.gov (United States)

Penchaszadeh, Pablo E.; Teso, Valeria; Pastorino, Guido

2017-12-01

The gastropods Odontocymbiola pescalia and Provocator corderoi and their egg capsules were collected by the R/V Puerto Deseado from the Mar del Plata Submarine Canyon ( 37°53‧S, at depths of 291-1404 m) and from Burdwood Bank ( 54°27‧S, 128-785 m). Odontocymbiola pescalia egg capsules measured 15.67 ± 3.38 mm in diameter. They were subspherical in shape with an external calcareous layer. Each egg capsule contained 3-5 embryos and white material as extra embryonic food. Embryos grew to a size of up to 9.3 ± 1.1 mm in mean shell length before hatching as crawling juveniles. The spawn of P. corderoi consisted of a single dome shaped egg capsule of 14.17 ± 1.5 mm in diameter, attached to hard substrata by a basal membrane with a rounded outline. A curved semilunar furrow (seam) on one side of the capsules was always present. The number of embryos per capsule was 2-6. Embryos hatched as crawling juveniles with a shell length of 5.9 ± 0.6 mm. The size and number of whorls in the hatchling shell suggested a slow rate of development, akin to many other deep-sea invertebrates. The egg capsules and reproductive development strategies of both species were compared with those from other congeneric representatives.

Salinity and temperature tolerance of the invasive freshwater gastropod Tarebia granifera

Directory of Open Access Journals (Sweden)

Renzo Perissinotto

2010-04-01

Full Text Available Invasive aquatic species, such as the gastropod Tarebia granifera, can cause ecological isturbances and potentially reduce biodiversity by displacing indigenous invertebrates. In South Africa, T. granifera was first recorded in an estuarine environment in the St Lucia Estuary. Its tolerance to salinity and temperature was investigated through the experimental manipulation of these factors. T. granifera can tolerate temperatures between 0 ºC and 47.5 ºC, allowing it to survive high temperature extremes. The species may also survive cold snaps and invade higher altitude areas. More remarkably, this snail survives high salinity for a relatively long time, as LS₅₀ (lethal salinity for 50% of the population was reached at 30 psu over 65–75 days. However, higher salinity adversely affected the T. granifera population. Snails acclimated to freshwater conditions and suddenly transferred to 30 psu experienced 100% mortality within 48 h. Snail activity also declined with increasing salinity. T. granifera’s environmental tolerance and parthenogenetic characteristics are the keys to successful introduction and establishment. Therefore, the management of T. granifera may prove diffcult in the short to medium term. The present findings constitute a contribution to the knowledge of biological invasions in Africa and to the understanding of estuarine invasions by T. granifera.

Role of the future creative universities in the triple helix of science and technology corridors

Directory of Open Access Journals (Sweden)

Iraj nabipour

2015-01-01

Full Text Available The science and technology corridor is a complex cluster containing universities, science parks, research centers, high-tech companies, venture capital, institutional and physical infrastructures, and human capital in a defined geography with its unique management and legal structure in association with the business space and knowledge-based products. In fact, the science and technology corridor reflects the concept of development based on the knowledge region (the especial region for science and technology. The knowledge region is clearly a triple helix phenomenon par excellence: universities, governments and businesses combine their efforts to construct a common advantage which they would not be able to offer on their own. The future creative universities in connection with the knowledge city-regions not only will deal with innovation and entrepreneurial training but also produce a competitive, vibrant environment with high indices for quality of life and full of green technologies. In this article, we will present functional interactions of the creative universities in the triple helix, particularly the missions for the Iranian universities of medical sciences. As a theoretical model, the complex interactions of Bushehr University of Medical Sciences and Health Services with Bushehr Science and Technology Corridor will be discussed.

Hepatoprotective and Antioxidant Activities of Tribulus Terrestris

NARCIS (Netherlands)

Harraz, Fathalla M; Ghazy, Nabila M; Hammoda, Hala M; Nafeaa, Abeer A.; Abdallah, Ingy I.

2015-01-01

Tribulus terrestris L. has been used in folk medicine throughout history. The present study examined the acute toxicity of the total ethanolic extract of T. Terrestris followed by investigation of the hepatoprotective activity of the total ethanolic extract and different fractions of the aerial

Debris disks as signposts of terrestrial planet formation

Science.gov (United States)

Raymond, S. N.; Armitage, P. J.; Moro-Martín, A.; Booth, M.; Wyatt, M. C.; Armstrong, J. C.; Mandell, A. M.; Selsis, F.; West, A. A.

2011-06-01

There exists strong circumstantial evidence from their eccentric orbits that most of the known extra-solar planetary systems are the survivors of violent dynamical instabilities. Here we explore the effect of giant planet instabilities on the formation and survival of terrestrial planets. We numerically simulate the evolution of planetary systems around Sun-like stars that include three components: (i) an inner disk of planetesimals and planetary embryos; (ii) three giant planets at Jupiter-Saturn distances; and (iii) an outer disk of planetesimals comparable to estimates of the primitive Kuiper belt. We calculate the dust production and spectral energy distribution of each system by assuming that each planetesimal particle represents an ensemble of smaller bodies in collisional equilibrium. Our main result is a strong correlation between the evolution of the inner and outer parts of planetary systems, i.e. between the presence of terrestrial planets and debris disks. Strong giant planet instabilities - that produce very eccentric surviving planets - destroy all rocky material in the system, including fully-formed terrestrial planets if the instabilities occur late, and also destroy the icy planetesimal population. Stable or weakly unstable systems allow terrestrial planets to accrete in their inner regions and significant dust to be produced in their outer regions, detectable at mid-infrared wavelengths as debris disks. Stars older than ~100 Myr with bright cold dust emission (in particular at λ ~ 70 μm) signpost dynamically calm environments that were conducive to efficient terrestrial accretion. Such emission is present around ~16% of billion-year old Solar-type stars. Our simulations yield numerous secondary results: 1) the typical eccentricities of as-yet undetected terrestrial planets are ~0.1 but there exists a novel class of terrestrial planet system whose single planet undergoes large amplitude oscillations in orbital eccentricity and inclination; 2) by

The fragmentation of Pangaea and Mesozoic terrestrial vertebrate biodiversity.

Science.gov (United States)

Vavrek, Matthew J

2016-09-01

During the Mesozoic (242-66 million years ago), terrestrial regions underwent a massive shift in their size, position and connectivity. At the beginning of the era, the land masses were joined into a single supercontinent called Pangaea. However, by the end of the Mesozoic, terrestrial regions had become highly fragmented, both owing to the drifting apart of the continental plates and the extremely high sea levels that flooded and divided many regions. How terrestrial biodiversity was affected by this fragmentation and large-scale flooding of the Earth's landmasses is uncertain. Based on a model using the species-area relationship (SAR), terrestrial vertebrate biodiversity would be expected to nearly double through the Mesozoic owing to continental fragmentation, despite a decrease of 24% in total terrestrial area. Previous studies of Mesozoic vertebrates have generally found increases in terrestrial diversity towards the end of the era, although these increases are often attributed to intrinsic or climatic factors. Instead, continental fragmentation over this time may largely explain any observed increase in terrestrial biodiversity. This study demonstrates the importance that non-intrinsic effects can have on the taxonomic success of a group, and the importance of geography to understanding past biodiversity. © 2016 The Author(s).

Ancient Terrestrial Carbon: Lost and Found

Science.gov (United States)

Freeman, K. H.

2017-12-01

Carbon fluxes in terrestrial environments dominate the global carbon cycle. The fluxes of terrestrial carbon are strongly tied to regional climate due to the influences of temperature, water, and nutrient dynamics on plant productivity. However, climate also influences the destruction of terrestrial organic matter, through weathering, erosion, and biomass loss via fire and oxidative microbial processes. Organic geochemical methods enable us to interrogate past terrestrial carbon dynamics and learn how continental processes might accelerate, or mitigate carbon transfer to the atmosphere, and the associated greenhouse warming. Terrestrial soil systems represent the weathering rind of the continents, and are inherently non-depositional and erosive. The production, transport, and depositional processes affecting organics in continental settings each impart their own biases on the amount and characteristics of preserved carbon. Typically, the best archives for biomarker records are sediments in ancient lakes or subaqueous fans, which represents a preservation bias that tends to favor wetter environments. Paleosols, or ancient soils, formed under depositional conditions that, for one reason or another, truncated soil ablation, erosion, or other loss processes. In modern soils, widely ranging organic carbon abundances are almost always substantially greater than the trace amounts of carbon left behind in ancient soils. Even so, measureable amounts of organic biomarkers persist in paleosols. We have been investigating processes that preserve soil organic carbon on geologic timescales, and how these mechanisms may be sensitive to past climate change. Climate-linked changes in temperature, moisture, pH, and weathering processes can impact carbon preservation via organo-mineral sorption, soil biogeochemistry, and stability based on the physical and chemical properties of organic compounds. These will be discussed and illustrated with examples from our studies of Cenozoic

Accelerator mass analyses of meteorites - carbon-14 terrestrial ages

International Nuclear Information System (INIS)

Miura, Y.; Rucklidge, J.; Beukens, R.; Fireman, E.

1988-01-01

Carbon-14 terrestrial ages of ten Antarctic meteorites have been measured by the IsoTrace accelerator mass spectrometry (AMS). The 14 C terrestrial age of 1 gram sample was determined from 14 C concentrations collected at melt and re-melt temperatures, compared with the 14 C concentration of the known Bruderheim chondrite. Yamato-790448 (LL3) chondrite was found to be the oldest terrestrial age of 3x10 4 years in the nine Yamato chondrites, whereas Yamato-791630 (L4) chondrite is considered to be the youngest chondrites less than thousand years. Allan Hills chondrite of ALH-77231 (L6) shows older terrestrial age than the nine Yamato chondrites. New accelerator data of the terrestrial age show higher accuracy with smaller sample than the previous counting method. (author)

Structure of the terrestrial planets

International Nuclear Information System (INIS)

Lyttleton, R.A.

1977-01-01

Recent reviews (cf. Runcorn, 1968; or Cook, 1972, 1975) on the structure of the planets omit reference to the phase-change hypothesis for the nature of the terrestrial core, despite that numerous prior predictions of the theory based on this hypothesis have subsequently been borne out as correct. These reviews also ignore the existence of theoretical calculations of the internal structure of Venus which can be computed with high accuracy by use of the terrestrial seismic data. Several examples of numerous mistakes committed in these reviews are pointed out. (Auth.)

Community Decadal Panel for Terrestrial Analogs to Mars

Science.gov (United States)

Barlow, N. G.; Farr, T.; Baker, V. R.; Bridges, N.; Carsey, F.; Duxbury, N.; Gilmore, M. S.; Green, J. R.; Grin, E.; Hansen, V.; Keszthelyi, L.; Lanagan, P.; Lentz, R.; Marinangeli, L.; Morris, P. A.; Ori, G. G.; Paillou, P.; Robinson, C.; Thomson, B.

2001-11-01

It is well recognized that interpretations of Mars must begin with the Earth as a reference. The most successful comparisons have focused on understanding geologic processes on the Earth well enough to extrapolate to Mars' environment. Several facets of terrestrial analog studies have been pursued and are continuing. These studies include field workshops, characterization of terrestrial analog sites for Mars, instrument tests, laboratory measurements (including analysis of martian meteorites), and computer and laboratory modeling. The combination of all these activities allows scientists to constrain the processes operating in specific terrestrial environments and extrapolate how similar processes could affect Mars. The Terrestrial Analogs for Mars Community Panel is considering the following two key questions: (1) How do terrestrial analog studies tie in to the MEPAG science questions about life, past climate, and geologic evolution of Mars, and (2) How can future instrumentation be used to address these questions. The panel is considering the issues of data collection, value of field workshops, data archiving, laboratory measurements and modeling, human exploration issues, association with other areas of solar system exploration, and education and public outreach activities.

Terrestrial magnetosphere

International Nuclear Information System (INIS)

Pande, D.C.; Agarwal, D.C.

1982-01-01

This paper presents a review about terrestrial magnetosphere. During the last few years considerable investigation have been carried out about the properties of Solar Wind and its interaction with planetary magnetic fields. It is therefore of high importance to accumulate all the investigations in a comprehensive form. The paper reviews the property of earth's magnetosphere, magnetosheath, magneto pause, polar cusps, bow shook and plasma sheath. (author)

The effect of k-cubic Dresselhaus spin—orbit coupling on the decay time of persistent spin helix states in semiconductor two-dimensional electron gases

International Nuclear Information System (INIS)

Chai Zheng; Hu Mao-Jin; Wang Rui-Qiang; Hu Liang-Bin

2014-01-01

We study the theoretical effect of k-cubic (i.e. cubic-in-momentum) Dresselhaus spin—orbit coupling on the decay time of persistent spin helix states in semiconductor two-dimensional electron gases. We show that the decay time of persistent spin helix states may be suppressed substantially by k-cubic Dresselhaus spin—orbit coupling, and after taking the effect of k-cubic Dresselhaus spin—orbit interaction into account, the theoretical results obtained accord both qualitatively and quantitatively with other recent experimental results. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Introduced Terrestrial Species (Future)

Data.gov (United States)

U.S. Environmental Protection Agency — These data represent predicted future potential distributions of terrestrial plants, animals, and pathogens non-native to the Middle-Atlantic region. These data are...

Space confinement and rotation stress induced self-organization of double-helix nanostructure: a nanotube twist with a moving catalyst head.

Science.gov (United States)

Zhao, Meng-Qiang; Zhang, Qiang; Tian, Gui-Li; Huang, Jia-Qi; Wei, Fei

2012-05-22

Inorganic materials with double-helix structure have attracted intensive attention due to not only their elegant morphology but also their amazing morphology-related potential applications. The investigation on the formation mechanism of the inorganic double-helix nanostructure is the first step for the fundamental studies of their materials or physical properties. Herein, we demonstrated the space confinement and rotation stress induced self-organization mechanism of the carbon nanotube (CNT)-array double helices under scanning electron microscopy by directly observing their formation process from individual layered double hydroxide flakes, which is a kind of hydrotalcite-like material composed of positively charged layers and charge-balancing interlayer anions. Space confinement is considered to be the most important extrinsic factor for the formation of CNT-array double helices. Synchronous growth of the CNT arrays oppositely from LDH flakes with space confinement on both sides at the same time is essential for the growth of CNT-array double helices. Coiling of the as-grown CNT arrays into double helices will proceed by self-organization, tending to the most stable morphology in order to release their internal rotation stress. Based on the demonstrated mechanism, effective routes were carried out to improve the selectivity for CNT-array double helices. The work provides a promising method for the fabrication of double-helix nanostructures with their two helices connected at the end by self-assembly.

TERRESTRIAL, HABITABLE-ZONE EXOPLANET FREQUENCY FROM KEPLER

International Nuclear Information System (INIS)

Traub, Wesley A.

2012-01-01

Data from Kepler's first 136 days of operation are analyzed to determine the distribution of exoplanets with respect to radius, period, and host-star spectral type. The analysis is extrapolated to estimate the percentage of terrestrial, habitable-zone (HZ) exoplanets. The Kepler census is assumed to be complete for bright stars (magnitude 0.5 Earth radius and periods β–1 , with β ≅ 0.71 ± 0.08; and an extrapolation to longer periods gives the frequency of terrestrial planets in the HZs of FGK stars as η ⊕ ≅ (34 ± 14)%. Thus about one-third of FGK stars are predicted to have at least one terrestrial, HZ planet.

Triple-resonance multidimensional NMR study of calmodulin complexed with the binding domain of skeletal muscle myosin light-chain kinase: Indication of a conformational change in the central helix

International Nuclear Information System (INIS)

Ikura, Mitsuhiko; Kay, L.E.; Bax, A.; Krinks, M.

1991-01-01

Heteronuclear 3D and 4D NMR experiments have been used to obtain 1 H, 13 C, and 15 N backbone chemical shift assignments in Ca 2+ -loaded clamodulin complexed with a 26-residue synthetic peptide (M13) corresponding to the calmodulin-bionding domain (residues 577-602) of rabbit skeletal muscle muosin light-chain kinase. Comparison of the chemical shift values with those observed in peptide-free calmodulin shows that binding of M13 peptide induces substantial chemical shift changes that are not localized in one particular region of the protein. The largest changes are found in the first helix of the Ca 2+ -binding site 1 (E11-E14), the N-terminal portion of the central helix (M72-D78), and the second helix of the Ca 2+ -binding site 4 (F141-M145). Analysis of backbone NOE connectivities indicates a change from α-helical to an extended conformation for residues 75-77 upon complexation with M13. Upon complexation with M13, a significant decrease in the amide exchange rate is observed for residues T110, L112, G113, and E114 at the end of the second helix of site 3

Spatial vision in Bombus terrestris

Directory of Open Access Journals (Sweden)

Aravin eChakravarthi

2016-02-01

Full Text Available Bombus terrestris is one of the most commonly used insect models to investigate visually guided behavior and spatial vision in particular. Two fundamental measures of spatial vision are spatial resolution and contrast sensitivity. In this study, we report the threshold of spatial resolution in B. terrestris and characterize the contrast sensitivity function of the bumblebee visual system for a dual choice discrimination task. We trained bumblebees in a Y-maze experimental set-up to associate a vertical sinusoidal grating with a sucrose reward, and a horizontal grating with absence of a reward. Using a logistic psychometric function, we estimated a resolution threshold of 0.21 cycles deg-1 of visual angle. This resolution is in the same range but slightly lower than that found in honeybees (Apis mellifera and A. cerana and another bumblebee species (B. impatiens. We also found that the contrast sensitivity of B. terrestris was 1.57 for the spatial frequency 0.09 cycles deg-1 and 1.26. for 0.18 cycles deg-1.

Apex Dips of Experimental Flux Ropes: Helix or Cusp?

Energy Technology Data Exchange (ETDEWEB)

Wongwaitayakornkul, Pakorn; Haw, Magnus A.; Bellan, Paul M. [Applied Physics, California Institute of Technology, Pasadena, CA 91125 (United States); Li, Hui [Theoretical Division, Los Alamos National Laboratory, Mail Stop B227, Los Alamos, NM 87545 (United States); Li, Shengtai, E-mail: pwongwai@caltech.edu, E-mail: mhaw@caltech.edu [Mathematical Modeling and Analysis, Los Alamos National Laboratory, Mail Stop B284, Los Alamos, NM 87545 (United States)

2017-10-20

We present a new theory for the presence of apex dips in certain experimental flux ropes. Previously such dips were thought to be projections of a helical loop axis generated by the kink instability. However, new evidence from experiments and simulations suggest that the feature is a 2D cusp rather than a 3D helix. The proposed mechanism for cusp formation is a density pileup region generated by nonlinear interaction of neutral gas cones emitted from fast-gas nozzles. The results indicate that density perturbations can result in large distortions of an erupting flux rope, even in the absence of significant pressure or gravitational forces. The density pileup at the apex also suppresses the m = 1 kink mode by acting as a stationary node. Consequently, more accurate density profiles should be considered when attempting to model the stability and shape of solar and astrophysical flux ropes.

Membrane-Dependent Effects of a Cytoplasmic Helix on the Structure and Drug Binding of the Influenza Virus M2 Protein

Science.gov (United States)

Cady, Sarah; Wang, Tuo; Hong, Mei

2011-01-01

The influenza A M2 protein forms a proton channel for virus infection and also mediates virus assembly and budding. The minimum protein length that encodes both functions contains the transmembrane (TM) domain (roughly residues 22 to 46) for the amantadine-sensitive proton-channel activity and an amphipathic cytoplasmic helix (roughly residues 45 to 62) for curvature induction and virus budding. However, structural studies involving the TM domain with or without the amphipathic helix differed on the drug-binding site. Here we use solid-state NMR spectroscopy to determine the amantadine binding site in the cytoplasmic-helix-containing M2(21–61). 13C-2H distance measurements of 13C-labeled protein and 2H-labeled amantadine showed that in DMPC bilayers, the first equivalent of drug bound S31 inside the M2(21–61) pore, similar to the behavior of M2TM in DMPC bilayers. The non-specific surface site of D44 observed in M2TM is disfavored in the longer peptide. Thus, the pharmacologically relevant drug-binding site in the fully functional M2(21–61) is S31 in the TM pore. Interestingly, when M2(21–61) was reconstituted into a virus-mimetic membrane containing 30% cholesterol, no chemical shift perturbation was observed for pore-lining residues, while M2TM in the same membrane exhibited drug-induced chemical shift changes. Reduction of the cholesterol level and the use of unsaturated phospholipids shifted the conformational equilibrium of M2TM fully to the bound state, but did not rescue drug binding to M2(21–61). These results suggest that the amphipathic helix, together with cholesterol, modulates the ability of the TM helices to bind amantadine. Thus, the M2 protein interacts with the lipid membrane and small-molecule inhibitors in a complex fashion, and a careful examination of the environmental dependence of the protein conformation is required to fully understand the structure-function relation of this protein. PMID:21661724

Soil manganese enrichment from industrial inputs: a gastropod perspective.

Directory of Open Access Journals (Sweden)

Despina-Maria Bordean

Full Text Available Manganese is one of the most abundant metal in natural environments and serves as an essential microelement for all living systems. However, the enrichment of soil with manganese resulting from industrial inputs may threaten terrestrial ecosystems. Several studies have demonstrated harmful effects of manganese exposure by cutaneous contact and/or by soil ingestion to a wide range of soil invertebrates. The link between soil manganese and land snails has never been made although these invertebrates routinely come in contact with the upper soil horizons through cutaneous contact, egg-laying, and feeding activities in soil. Therefore, we have investigated the direct transfer of manganese from soils to snails and assessed its toxicity at background concentrations in the soil. Juvenile Cantareus aspersus snails were caged under semi-field conditions and exposed first, for a period of 30 days, to a series of soil manganese concentrations, and then, for a second period of 30 days, to soils with higher manganese concentrations. Manganese levels were measured in the snail hepatopancreas, foot, and shell. The snail survival and shell growth were used to assess the lethal and sublethal effects of manganese exposure. The transfer of manganese from soil to snails occurred independently of food ingestion, but had no consistent effect on either the snail survival or shell growth. The hepatopancreas was the best biomarker of manganese exposure, whereas the shell did not serve as a long-term sink for this metal. The kinetics of manganese retention in the hepatopancreas of snails previously exposed to manganese-spiked soils was significantly influenced by a new exposure event. The results of this study reveal the importance of land snails for manganese cycling in terrestrial biotopes and suggest that the direct transfer from soils to snails should be considered when precisely assessing the impact of anthropogenic Mn releases on soil ecosystems.

BAROMETRIC PRESSURE and Other Data from ALPHA HELIX From Chukchi Sea and Others from 19930709 to 19930807 (NODC Accession 9400062)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Conductivity, Temperature and Depth (CTD) and other data were collected in Bering Sea, Chukchi Sea. Data was collected from Ship ALPHA HELIX cruise Aleutian...

Temperature, salinity and transmissivity data from the Alpha Helix in the Arctic Ocean, 2000 - 2004 (NODC Accession 0059005)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This is calibrated CTD downcast data from five Alpha Helix cruises: HX235, 8/1/2000 - 9/30/2000 HX250, 9/1/2001 - 9/30/2001 HX260, 6/1/2002 - 6/30/2002 HX274,...

Dual catalytic purpose of the tungsten filament during the synthesis of single-helix carbon microcoils by hot-wire CVD

CSIR Research Space (South Africa)

Oliphant, CJ

2009-10-01

Full Text Available This paper reports on the deposition of crystalline single-helix carbon microcoils, in the as-deposited state, by the hot-wire chemical vapor deposition process without any special preparation of nano-sized transition metal catalysts and subsequent...

Soil and terrestrial biology studies

International Nuclear Information System (INIS)

Anon.

1976-01-01

Soil and terrestrial biology studies focused on developing an understanding of the uptake of gaseous substances from the atmosphere by plants, biodegradation of oil, and the movement of Pu in the terrestrial ecosystems of the southeastern United States. Mathematical models were developed for SO 2 and tritium uptake from the atmosphere by plants; the uptake of tritium by soil microorganisms was measured; and the relationships among the Pu content of soil, plants, and animals of the Savannah River Plant area were studied. Preliminary results are reported for studies on the biodegradation of waste oil on soil surfaces

The early evolution of the atmospheres of terrestrial planets

CERN Document Server

Raulin, François; Muller, Christian; Nixon, Conor; Astrophysics and Space Science Proceedings : Volume 35

2013-01-01

“The Early Evolution of the Atmospheres of Terrestrial Planets” presents the main processes participating in the atmospheric evolution of terrestrial planets. A group of experts in the different fields provide an update of our current knowledge on this topic. Several papers in this book discuss the key role of nitrogen in the atmospheric evolution of terrestrial planets. The earliest setting and evolution of planetary atmospheres of terrestrial planets is directly associated with accretion, chemical differentiation, outgassing, stochastic impacts, and extremely high energy fluxes from their host stars. This book provides an overview of the present knowledge of the initial atmospheric composition of the terrestrial planets. Additionally it includes some papers about the current exoplanet discoveries and provides additional clues to our understanding of Earth’s transition from a hot accretionary phase into a habitable world. All papers included were reviewed by experts in their respective fields. We are ...

Water vapor estimation using digital terrestrial broadcasting waves

Science.gov (United States)

Kawamura, S.; Ohta, H.; Hanado, H.; Yamamoto, M. K.; Shiga, N.; Kido, K.; Yasuda, S.; Goto, T.; Ichikawa, R.; Amagai, J.; Imamura, K.; Fujieda, M.; Iwai, H.; Sugitani, S.; Iguchi, T.

2017-03-01

A method of estimating water vapor (propagation delay due to water vapor) using digital terrestrial broadcasting waves is proposed. Our target is to improve the accuracy of numerical weather forecast for severe weather phenomena such as localized heavy rainstorms in urban areas through data assimilation. In this method, we estimate water vapor near a ground surface from the propagation delay of digital terrestrial broadcasting waves. A real-time delay measurement system with a software-defined radio technique is developed and tested. The data obtained using digital terrestrial broadcasting waves show good agreement with those obtained by ground-based meteorological observation. The main features of this observation are, no need for transmitters (receiving only), applicable wherever digital terrestrial broadcasting is available and its high time resolution. This study shows a possibility to estimate water vapor using digital terrestrial broadcasting waves. In the future, we will investigate the impact of these data toward numerical weather forecast through data assimilation. Developing a system that monitors water vapor near the ground surface with time and space resolutions of 30 s and several kilometers would improve the accuracy of the numerical weather forecast of localized severe weather phenomena.

Identification of the roles of individual amino acid residues of the helix E of the major antenna of photosystem II (LHCII) by alanine scanning mutagenesis.

Science.gov (United States)

Liu, Cheng; Rao, Yan; Zhang, Lei; Yang, Chunhong

2014-10-01

The functions of the helix E (W97-F105), an amphiphilic lumenal 310 helix of the major antenna of photosystem II (LHCII), are still unidentified. To elucidate the roles of individual amino acid residue of the helix E, alanine scanning mutagenesis has been performed to mutate every residue of this domain to alanine. The influence of every alanine substitution on the structure and function of LHCII has been investigated biochemically and spectroscopically. The results show that all mutations have little impact on the pigment binding and configuration. However, many mutants presented decreased thermo- or photo-stability compared with the wild type, highlighting the significance of this helix to the stability of LHCII. The most critical residue for stability is W97. The mutant W97A yielded very fragile trimeric pigment protein complexes. The structural analysis revealed that the hydrogen bonding and aromatic interactions between W97, F195, F194 and a water molecule contributed greatly to the stability of LHCII. Moreover, Q103A and F105A have been identified to be able to reinforce the tendency of aggregation in vitro. The structural analysis suggested that the enhancement in aggregation formation for Q103A and F105A might be attributed to the changing hydrophobicity of the region. © The Authors 2014. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.

Single-photon absorption of isolated collagen mimetic peptides and triple-helix models in the VUV-X energy range

NARCIS (Netherlands)

Schwob, Lucas; Lalande, Mathieu; Rangama, Jimmy; Egorov, Dmitrii; Hoekstra, Ronnie; Pandey, Rahul; Eden, Samuel; Schlathölter, Thomas; Vizcaino, Violaine; Poully, Jean-Christophe

2017-01-01

Cartilage and tendons owe their special mechanical properties to the fibrous collagen structure. These strong fibrils are aggregates of a sub-unit consisting of three collagen proteins wound around each other in a triple helix. Even though collagen is the most abundant protein in the human body, the

Stakeholder engagement in quattro helix model for mobile phone reverse logistics in Indonesia: a conceptual framework

Science.gov (United States)

Maheswari, H.; Yudoko, G.; Adhiutama, A.

2017-12-01

The number of e-waste from mobile phone industry is still dominating until now. This is happened because there is no mutual commitment from all of parties i.e. businesses, government, and societies to reduce the use of mobile phone that has the shortest product life cycle. There are many researches study about firms’ motivation and government’s role, other discuss about actions of communities in supporting reverse logistics implementation. Unfortunately, research about engagement mechanism that involving all parties is still rare. Therefore, it is important to find the engagement model through this conceptual paper and it is expected useful to build the novel model. Through literature review, the results of this research are establishing the Quattro helix model as the appropriate structure to build the robust team by exploring stakeholder theories; mapping the engagement model either in form of collaboration or participation that consider stakeholders’ role and motivation and finding six types of engagement that consider their interest; and determining the novel model of engagement through Quattro helix model for implementing reverse logistics in handling e-waste by describing the linkage and the gaps among existing model.

An α‐Helix‐Mimicking 12,13‐Helix: Designed α/β/γ‐Foldamers as Selective Inhibitors of Protein–Protein Interactions

Science.gov (United States)

Grison, Claire M.; Miles, Jennifer A.; Robin, Sylvie

2016-01-01

Abstract A major current challenge in bioorganic chemistry is the identification of effective mimics of protein secondary structures that act as inhibitors of protein–protein interactions (PPIs). In this work, trans‐2‐aminocyclobutanecarboxylic acid (tACBC) was used as the key β‐amino acid component in the design of α/β/γ‐peptides to structurally mimic a native α‐helix. Suitably functionalized α/β/γ‐peptides assume an α‐helix‐mimicking 12,13‐helix conformation in solution, exhibit enhanced proteolytic stability in comparison to the wild‐type α‐peptide parent sequence from which they are derived, and act as selective inhibitors of the p53/hDM2 interaction. PMID:27467859

The decadal state of the terrestrial carbon cycle

NARCIS (Netherlands)

Velde, van der I.R.; Bloom, J.; Exbrayat, J.; Feng, L.; Williams, M.

2016-01-01

The terrestrial carbon cycle is currently the least constrained component of the global carbon budget. Large uncertainties stem from a poor understanding of plant carbon allocation, stocks, residence times, and carbon use efficiency. Imposing observational constraints on the terrestrial carbon cycle

Phytopharmacology of Tribulus terrestris.

Science.gov (United States)

Shahid, M; Riaz, M; Talpur, M M A; Pirzada, T

2016-01-01

Tribulus terrestris is an annual herb which belongs to the Zygophyllaceae family. This plant has been used in traditional medicine for the treatment of various diseases for hundreds of decades. The main active phytoconstituents of this plant include flavonoids, alkaloids, saponins, lignin, amides, and glycosides. The plant parts have different pharmacological activities including aphrodisiac, antiinflammatory, antimicrobial and antioxidant potential. T. terrestris is most often used for infertility and loss of libido. It has potential application as immunomodulatory, hepatoprotective, hypolipidemic, anthelmintic and anticarcinogenic activities. The aim of the present article is to create a database for further investigation of the phytopharmacological properties of this plant to promote research. This study will definitely help to confirm its traditional use along with its value-added utility, eventually leading to higher revenues from the plant.

Equilibration of the terrestrial water, nitrogen, and carbon cycles

OpenAIRE

Schimel, David S.; Braswell, B. H.; Parton, W. J.

1997-01-01

Recent advances in biologically based ecosystem models of the coupled terrestrial, hydrological, carbon, and nutrient cycles have provided new perspectives on the terrestrial biosphere’s behavior globally, over a range of time scales. We used the terrestrial ecosystem model Century to examine relationships between carbon, nitrogen, and water dynamics. The model, run to a quasi-steady-state, shows strong correlations between carbon, water, and nitrogen fluxes that l...

Taiwan's industrial heavy metal pollution threatens terrestrial biota

International Nuclear Information System (INIS)

Hsu, M.J.; Selvaraj, K.; Agoramoorthy, G.

2006-01-01

The bioconcentration levels of essential (Cu, Fe, Mg, Mn, and Zn) and non-essential (As, Cd, Hg, Pb, and Sn) elements have been investigated in different terrestrial biota such as fungi, plant, earthworm, snail, crab, insect, amphibian, lizard, snake, and bat including the associated soil, to investigate the ecosystem health status in Kenting National Park, Taiwan. High bioconcentrations of Cd, Hg, and Sn in snail, earthworm, crab, lizard, snake, and bat indicated a contaminated terrestrial ecosystem. High concentrations of Cd, Hg, and Sn in plant species, effective bioaccumulation of Cd by earthworm, snail, crab and bat, as well as very high levels of Hg found in invertebrates, amphibians, and reptiles revealed a strong influence from industrial pollution on the biotic community. This study for the first time presents data on the impact of heavy metal pollution on various terrestrial organisms in Taiwan. - Metal effects occur at any terrestrial levels in Taiwan

An Intramolecular Salt Bridge in Bacillus thuringiensis Cry4Ba Toxin Is Involved in the Stability of Helix α-3, Which Is Needed for Oligomerization and Insecticidal Activity.

Science.gov (United States)

Pacheco, Sabino; Gómez, Isabel; Sánchez, Jorge; García-Gómez, Blanca-Ines; Soberón, Mario; Bravo, Alejandra

2017-10-15

Bacillus thuringiensis three-domain Cry toxins kill insects by forming pores in the apical membrane of larval midgut cells. Oligomerization of the toxin is an important step for pore formation. Domain I helix α-3 participates in toxin oligomerization. Here we identify an intramolecular salt bridge within helix α-3 of Cry4Ba (D111-K115) that is conserved in many members of the family of three-domain Cry toxins. Single point mutations such as D111K or K115D resulted in proteins severely affected in toxicity. These mutants were also altered in oligomerization, and the mutant K115D was more sensitive to protease digestion. The double point mutant with reversed charges, D111K-K115D, recovered both oligomerization and toxicity, suggesting that this salt bridge is highly important for conservation of the structure of helix α-3 and necessary to promote the correct oligomerization of the toxin. IMPORTANCE Domain I has been shown to be involved in oligomerization through helix α-3 in different Cry toxins, and mutations affecting oligomerization also elicit changes in toxicity. The three-dimensional structure of the Cry4Ba toxin reveals an intramolecular salt bridge in helix α-3 of domain I. Mutations that disrupt this salt bridge resulted in changes in Cry4Ba oligomerization and toxicity, while a double point reciprocal mutation that restored the salt bridge resulted in recovery of toxin oligomerization and toxicity. These data highlight the role of oligomer formation as a key step in Cry4Ba toxicity. Copyright © 2017 American Society for Microbiology.

The gastropod Phorcus sauciatus (Koch, 1845) along the north-west Iberian Peninsula: filling historical gaps

Science.gov (United States)

Rubal, Marcos; Veiga, Puri; Moreira, Juan; Sousa-Pinto, Isabel

2014-03-01

The intertidal gastropod Phorcus sauciatus is a subtropical grazer that reaches its northern boundary in the Iberian Peninsula. Distribution of P. sauciatus along the Iberian Peninsula shows, however, gaps in its distribution. The present study was aimed at detecting possible recent changes on the population structure and distribution of P. sauciatus along the north-west Atlantic coast of the Iberian Peninsula. To achieve this aim, we adopted a qualitative sampling design to explore the presence of P. sauciatus along a region within its historical gap of distribution (north Portuguese coast). In addition, a quantitative sampling design was adopted to test hypotheses about the abundance and size structure of P. sauciatus populations among regions with different historical records of its abundance and among shores with different exposure. Results showed that P. sauciatus was present along the north Portuguese coast. However, the abundance and size structure of the newly settled populations were significantly different to those of the historically recorded populations. Moreover, P. sauciatus was able to establish populations at sheltered shores. Considering these results, we propose models for the distribution of P. sauciatus along the Iberian Peninsula, based on effects of sea surface temperature, and to explain the size-frequency of their populations based on their density.

Terrestrial Energy bets on molten salt reactors

International Nuclear Information System (INIS)

Anon.

2015-01-01

Terrestrial Energy is a Canadian enterprise, founded in 2013, for marketing the integral molten salt reactor (IMSR). A first prototype (called MSRE and with an energy output of 8 MW) was designed and operated between 1965 and 1969 by the Oak Ridge National Laboratory. IMSR is a small, modular reactor with a thermal energy output of 400 MW. According to Terrestrial Energy the technology of conventional power reactors is too complicated and too expensive. On the contrary IMSR's technology appears to be simple, easy to operate and affordable. With a staff of 30 people Terrestrial Energy appears to be a start-up in the nuclear sector. A process of pre-licensing will be launched in 2016 with the Canadian nuclear safety authority. (A.C.)

Temperature, salinity, conductivity, pressure, transmissivity measurements collected using CTD from the Alpha Helix in the Chukchi Sea during 1996 (NODC Accession 0061042)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature, salinity, conductivity, pressure, and transmissivity data gathered by CTD from the Alpha Helix (cruise HX194), September 1996

Defining the transmembrane helix of M2 protein from influenza A by molecular dynamics simulations in a lipid bilayer

NARCIS (Netherlands)

Forrest, LR; Tieleman, DP; Sansom, MSP

Integral membrane proteins containing at least one transmembrane (TM) alpha-helix are believed to account for between 20% and 30% of most genomes. There are several algorithms that accurately predict the number and position of TM helices within,a membrane protein sequence. However, these methods

Interworking evolution of mobile satellite and terrestrial networks

Science.gov (United States)

Matyas, R.; Kelleher, P.; Moller, P.; Jones, T.

1993-01-01

There is considerable interest among mobile satellite service providers in interworking with terrestrial networks to provide a universal global network. With such interworking, subscribers may be provided a common set of services such as those planned for the Public Switched Telephone Network (PSTN), the Integrated Services Digital Network (ISDN), and future Intelligent Networks (IN's). This paper first reviews issues in satellite interworking. Next the status and interworking plans of terrestrial mobile communications service providers are examined with early examples of mobile satellite interworking including a discussion of the anticipated evolution towards full interworking between mobile satellite and both fixed and mobile terrestrial networks.

Divergent apparent temperature sensitivity of terrestrial ecosystem respiration

Science.gov (United States)

Bing Song; Shuli Niu; Ruise Luo; Yiqi Luo; Jiquan Chen; Guirui Yu; Janusz Olejnik; Georg Wohlfahrt; Gerard Kiely; Ako Noormets; Leonardo Montagnani; Alessandro Cescatti; Vincenzo Magliulo; Beverly Elizabeth Law; Magnus Lund; Andrej Varlagin; Antonio Raschi; Matthias Peichl; Mats B. Nilsson; Lutz Merbold

2014-01-01

Recent studies revealed convergent temperature sensitivity of ecosystem respiration (Re) within aquatic ecosystems and between terrestrial and aquatic ecosystems. We do not know yet whether various terrestrial ecosystems have consistent or divergent temperature sensitivity. Here, we synthesized 163 eddy covariance flux sites across the world and...

Evolutionary tracks of the terrestrial planets

International Nuclear Information System (INIS)

Matsui, Takafumi; Abe, Yutaka

1987-01-01

On the basis of the model proposed by Matsui and Abe, the authors show that two major factors - distance from the Sun and the efficiency of retention of accretional energy - control the early evolution of the terrestrial planets. A diagram of accretional energy versus the optical depth of a proto-atmosphere provides a means to follow the evolutionary track of surface temperature of the terrestrial planets and an explanation for why the third planet in our solar system is an 'aqua'-planet. 15 refs; 3 figs

Intersystem Interference Reduction for Overlaid HAPS-Terrestrial CDMA System

Science.gov (United States)

Huang, Jeng-Ji; Wang, Wei-Ting; Li, Mingfu; Shiung, David; Ferng, Huei-Wen

In this letter, we propose that directional antennas, combined with power management, be incorporated to reduce intersystem interference in a shared band overlaid high altitude platform station (HAPS)-terrestrial code division multiple access (CDMA) system. To eliminate the HAPS to terrestrial interference, the HAPS is accessed only via directional antennas under the proposed scheme. By doing so, the uplink power to the HAPS can accordingly be increased, so that the terrestrial to HAPS interference is also effectively suppressed.

A Triple Helix Strategy for Promoting SME Development: The Case of a Dried Banana Community Enterprise in Thailand

Science.gov (United States)

Yuwawutto, Sauwapa; Smitinont, Thitapha; Charoenanong, Numtip; Yokakul, Nattaka; Chatratana, Sonchai; Zawdie, Girma

2010-01-01

This paper examines the university-industry-government relationship as a mechanism for enhancing the efficiency and competitiveness of small and medium-sized enterprises (SMEs). The case of a community enterprise producing dried banana products in the north of Thailand is used to demonstrate the significance of the Triple Helix model for business…

Investigation on the toxic potential of Tribulus terrestris in vitro.

Science.gov (United States)

Abudayyak, M; Jannuzzi, A T; Özhan, G; Alpertunga, B

2015-04-01

Tribulus terrestris L. (Zygophyllaceae) has been commonly used to energize, vitalize, and improve sexual function and physical performance in men. This study investigates the potential cytotoxic and genotoxic, and endocrine disrupting activities of T. terrestris in vitro. The whole T. terrestris plant was extracted with water, methanol, and chloroform. The genotoxic potential of T. terrestris extracts at 3-2400 µg/mL was assessed by Comet assay in a rat kidney cell line (NRK-52E) and by Ames assay in Salmonella typhimurium TA98 and TA100 strains. Endocrine disrupting effects of the extracts at concentrations of 0.22-25 000 µg/mL were assessed by YES/YAS assay in Saccharomyces cerevisiae. Cytotoxic activity of the extracts was determined by the MTT test in NRK-52E cells. The different exposure times were used for four tests (3-48 h). The methanol extract of T. terrestris IC50 value was 160 µg/mL. The other extracts did not show cytotoxic effects. In the Comet and Ames genotoxicity assays, none of the extracts possessed genotoxic activities at concentrations of 0-2400 µg/mL. Only the water extract of T. terrestris induced frame shift mutations after metabolic activation. The water extract also showed estrogenic activity by YES/YAS assay in S. cerevisiae at concentrations ≥27 µg/mL (≥2.6-fold), while the other T. terrestris extracts had anti-estrogenic properties. Tribulus terrestris had estrogenic and genotoxic activities. The study was useful in determining its toxicological effects and the precautions regarding consumption.

BAROMETRIC PRESSURE and Other Data from ALPHA HELIX From North Pacific Ocean and Others from 19931016 to 19931103 (NODC Accession 9400051)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Conductivity, Temperature and Depth (CTD) and other data were collected in Bering Sea and North Pacific Ocean. Data was collected from Ship ALPHA HELIX cruise...

Characterization of the biomechanical properties of T4 pili expressed by Streptococcus pneumoniae--a comparison between helix-like and open coil-like pili.

Science.gov (United States)

Castelain, Mickaël; Koutris, Efstratios; Andersson, Magnus; Wiklund, Krister; Björnham, Oscar; Schedin, Staffan; Axner, Ove

2009-07-13

Bacterial adhesion organelles, known as fimbria or pili, are expressed by gram-positive as well as gram-negative bacteria families. These appendages play a key role in the first steps of the invasion and infection processes, and they therefore provide bacteria with pathogenic abilities. To improve the knowledge of pili-mediated bacterial adhesion to host cells and how these pili behave under the presence of an external force, we first characterize, using force measuring optical tweezers, open coil-like T4 pili expressed by gram-positive Streptococcus pneumoniae with respect to their biomechanical properties. It is shown that their elongation behavior can be well described by the worm-like chain model and that they possess a large degree of flexibility. Their properties are then compared with those of helix-like pili expressed by gram-negative uropathogenic Escherichia coli (UPEC), which have different pili architecture. The differences suggest that these two types of pili have distinctly dissimilar mechanisms to adhere and sustain external forces. Helix-like pili expressed by UPEC bacteria adhere to host cells by single adhesins located at the distal end of the pili while their helix-like structures act as shock absorbers to dampen the irregularly shear forces induced by urine flow and to increase the cooperativity of the pili ensemble, whereas open coil-like pili expressed by S. pneumoniae adhere to cells by a multitude of adhesins distributed along the pili. It is hypothesized that these two types of pili represent different strategies of adhering to host cells in the presence of external forces. When exposed to significant forces, bacteria expressing helix-like pili remain attached by distributing the external force among a multitude of pili, whereas bacteria expressing open coil-like pili sustain large forces primarily by their multitude of binding adhesins which presumably detach sequentially.

A conserved degron containing an amphipathic helix regulates the cholesterol-mediated turnover of human squalene monooxygenase, a rate-limiting enzyme in cholesterol synthesis.

Science.gov (United States)

Chua, Ngee Kiat; Howe, Vicky; Jatana, Nidhi; Thukral, Lipi; Brown, Andrew J

2017-12-08

Cholesterol biosynthesis in the endoplasmic reticulum (ER) is tightly controlled by multiple mechanisms to regulate cellular cholesterol levels. Squalene monooxygenase (SM) is the second rate-limiting enzyme in cholesterol biosynthesis and is regulated both transcriptionally and post-translationally. SM undergoes cholesterol-dependent proteasomal degradation when cholesterol is in excess. The first 100 amino acids of SM (designated SM N100) are necessary for this degradative process and represent the shortest cholesterol-regulated degron identified to date. However, the fundamental intrinsic characteristics of this degron remain unknown. In this study, we performed a series of deletions, point mutations, and domain swaps to identify a 12-residue region (residues Gln-62-Leu-73), required for SM cholesterol-mediated turnover. Molecular dynamics and circular dichroism revealed an amphipathic helix within this 12-residue region. Moreover, 70% of the variation in cholesterol regulation was dependent on the hydrophobicity of this region. Of note, the earliest known Doa10 yeast degron, Deg1, also contains an amphipathic helix and exhibits 42% amino acid similarity with SM N100. Mutating SM residues Phe-35/Ser-37/Leu-65/Ile-69 into alanine, based on the key residues in Deg1, blunted SM cholesterol-mediated turnover. Taken together, our results support a model whereby the amphipathic helix in SM N100 attaches reversibly to the ER membrane depending on cholesterol levels; with excess, the helix is ejected and unravels, exposing a hydrophobic patch, which then serves as a degradation signal. Our findings shed new light on the regulation of a key cholesterol synthesis enzyme, highlighting the conservation of critical degron features from yeast to humans. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Reproductive cycles in tropical intertidal gastropods are timed around tidal amplitude cycles.

Science.gov (United States)

Collin, Rachel; Kerr, Kecia; Contolini, Gina; Ochoa, Isis

2017-08-01

Reproduction in iteroparous marine organisms is often timed with abiotic cycles and may follow lunar, tidal amplitude, or daily cycles. Among intertidal marine invertebrates, decapods are well known to time larval release to coincide with large amplitude nighttime tides, which minimizes the risk of predation. Such bimonthly cycles have been reported for few other intertidal invertebrates. We documented the reproduction of 6 gastropod species from Panama to determine whether they demonstrate reproductive cycles, whether these cycles follow a 2-week cycle, and whether cycles are timed so that larval release occurs during large amplitude tides. Two of the species ( Crepidula cf. marginalis and Nerita scabricosta ) showed nonuniform reproduction, but without clear peaks in timing relative to tidal or lunar cycles. The other 4 species show clear peaks in reproduction occurring every 2 weeks. In 3 of these species ( Cerithideopsis carlifornica var. valida, Littoraria variegata , and Natica chemnitzi ), hatching occurred within 4 days of the maximum amplitude tides. Siphonaria palmata exhibit strong cycles, but reproduction occurred during the neap tides. Strong differences in the intensity of reproduction of Cerithideopsis carlifornica , and in particular, Littoraria variegata , between the larger and smaller spring tides of a lunar month indicate that these species time reproduction with the tidal amplitude cycle rather than the lunar cycle. For those species that reproduce during both the wet and dry seasons, we found that reproductive timing did not differ between seasons despite strong differences in temperature and precipitation. Overall, we found that most (4/6) species have strong reproductive cycles synchronized with the tidal amplitude cycle and that seasonal differences in abiotic factors do not alter these cycles.

On the mechanism of irradiation effect on the function of Helix pomatia neuron Na+, K+-pump

International Nuclear Information System (INIS)

Ajrapetyan, S.N.; Egorova, E.G.; Sagiyan, A.A.; Dadalyan, S.S.; Dvoretskij, A.I.; Sulejmonyan, M.A.

1987-01-01

Mechanism of irradiation effect on passive permeability, Na + /Ca 2+ exchange, Na + , K + -pump function intensity, the number of membrane functionally active pump units (Na + , K + -ATP-ase molecules) was determined using Helix pomatia and nervous ganglions isolated from them and irradiated by 5.16 Kl/kg dose. The data obtained show that ionizing radiation leads to obvious destructions in the mechanisms of neuron Na + , K + -pump functioning

THE COMPOSITIONAL DIVERSITY OF EXTRASOLAR TERRESTRIAL PLANETS. II. MIGRATION SIMULATIONS

International Nuclear Information System (INIS)

Carter-Bond, Jade C.; O'Brien, David P.; Raymond, Sean N.

2012-01-01

Prior work has found that a variety of terrestrial planetary compositions are expected to occur within known extrasolar planetary systems. However, such studies ignored the effects of giant planet migration, which is thought to be very common in extrasolar systems. Here we present calculations of the compositions of terrestrial planets that formed in dynamical simulations incorporating varying degrees of giant planet migration. We used chemical equilibrium models of the solid material present in the disks of five known planetary host stars: the Sun, GJ 777, HD4203, HD19994, and HD213240. Giant planet migration has a strong effect on the compositions of simulated terrestrial planets as the migration results in large-scale mixing between terrestrial planet building blocks that condensed at a range of temperatures. This mixing acts to (1) increase the typical abundance of Mg-rich silicates in the terrestrial planets' feeding zones and thus increase the frequency of planets with Earth-like compositions compared with simulations with static giant planet orbits, and (2) drastically increase the efficiency of the delivery of hydrous phases (water and serpentine) to terrestrial planets and thus produce waterworlds and/or wet Earths. Our results demonstrate that although a wide variety of terrestrial planet compositions can still be produced, planets with Earth-like compositions should be common within extrasolar planetary systems.

Release of lungworm larvae from snails in the environment: potential for alternative transmission pathways.

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Alessio Giannelli

2015-04-01

Full Text Available Gastropod-borne parasites may cause debilitating clinical conditions in animals and humans following the consumption of infected intermediate or paratenic hosts. However, the ingestion of fresh vegetables contaminated by snail mucus and/or water has also been proposed as a source of the infection for some zoonotic metastrongyloids (e.g., Angiostrongylus cantonensis. In the meantime, the feline lungworms Aelurostrongylus abstrusus and Troglostrongylus brevior are increasingly spreading among cat populations, along with their gastropod intermediate hosts. The aim of this study was to assess the potential of alternative transmission pathways for A. abstrusus and T. brevior L3 via the mucus of infected Helix aspersa snails and the water where gastropods died. In addition, the histological examination of snail specimens provided information on the larval localization and inflammatory reactions in the intermediate host.Twenty-four specimens of H. aspersa received ~500 L1 of A. abstrusus and T. brevior, and were assigned to six study groups. Snails were subjected to different mechanical and chemical stimuli throughout 20 days in order to elicit the production of mucus. At the end of the study, gastropods were submerged in tap water and the sediment was observed for lungworm larvae for three consecutive days. Finally, snails were artificially digested and recovered larvae were counted and morphologically and molecularly identified. The anatomical localization of A. abstrusus and T. brevior larvae within snail tissues was investigated by histology. L3 were detected in the snail mucus (i.e., 37 A. abstrusus and 19 T. brevior and in the sediment of submerged specimens (172 A. abstrusus and 39 T. brevior. Following the artificial digestion of H. aspersa snails, a mean number of 127.8 A. abstrusus and 60.3 T. brevior larvae were recovered. The number of snail sections positive for A. abstrusus was higher than those for T. brevior.Results of this study

Terrestrial propagation of long electromagnetic waves

CERN Document Server

Galejs, Janis; Fock, V A

2013-01-01

Terrestrial Propagation of Long Electromagnetic Waves deals with the propagation of long electromagnetic waves confined principally to the shell between the earth and the ionosphere, known as the terrestrial waveguide. The discussion is limited to steady-state solutions in a waveguide that is uniform in the direction of propagation. Wave propagation is characterized almost exclusively by mode theory. The mathematics are developed only for sources at the ground surface or within the waveguide, including artificial sources as well as lightning discharges. This volume is comprised of nine chapte

Research progress in airborne surveys of terrestrial gamma radiation

International Nuclear Information System (INIS)

Burson, Z.G.

1974-01-01

Progress during the last few years in airborne surveys of terrestrial gamma radiation, i.e. in the measuring, recording, and interpreting of gamma ray signals in NaI(Tl) crystals, is discussed. Non-terrestrial background contributions have been accurately characterized. The feasibility of determining the water equivalent of snow cover by aerial survey techniques has been demonstrated. Repeat surveys over areas surrounding reactor sites can now be used to detect average differences of less than 1.0 μR/hr in terrestrial gamma radiation levels. New data acquisition and recording systems allow isotope concentrations and total inventories to be measured in spatial resolutions of a few hundred feet. Aerial survey data have been combined with population distribution data to obtain population exposure values from natural terrestrial gamma radiation around reactor sites

Grazing livestock are exposed to terrestrial cyanobacteria

OpenAIRE

McGorum , Bruce C; Pirie , R Scott; Glendinning , Laura; McLachlan , Gerry; Metcalf , James S; Banack , Sandra A; Cox , Paul A; Codd , Geoffrey A

2015-01-01

While toxins from aquatic cyanobacteria are a well-recognised cause of disease in birds and animals, exposure of grazing livestock to terrestrial cyanobacteria has not been described. This study identified terrestrial cyanobacteria, predominantly Phormidium spp., in the biofilm of plants from most livestock fields investigated. Lower numbers of other cyanobacteria, microalgae and fungi were present on many plants. Cyanobacterial 16S rDNA, predominantly from Phormidium spp., was detected in al...

Coexistence of Terrestrial and HAP 3G Networks during Disaster Scenarios

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P. Pechac

2008-12-01

Full Text Available The aim of this paper is to show the possible coexistence of an HAP and a terrestrial component of 3G networks at a single carrier frequency. The main goal is to compare the basic parameters of terrestrial and HAP com-ponent 3G networks modeled in suburban (macrocell and urban (macro/microcell areas and to demonstrate the way they impact on each other. This study should present what we assume are the better capabilities of HAP 3G networks compared to their terrestrial counterparts. The parameters of the HAP and terrestrial component of 3G networks, were the terrestrial cells to be disabled during disasters, are also presented.

Broad-Scale Comparison of Photosynthesis in Terrestrial and Aquatic Plant Communities

DEFF Research Database (Denmark)

Sand-Jensen, Kaj; Krause-Jensen, D.

1997-01-01

Comparisons of photosynthesis in terrestrial and aquatic habitats have been impaired by differences in methods and time-scales of measurements. We compiled information on gross photosynthesis at high irradiance and photosynthetic efficiency at low irradiance from 109 published terrestrial studies...... communities probably due to more efficient light utilization and gas exchange in the terrestrial habitats. By contrast only small differences were found within different aquatic plant communities or within different terrestrial plant communities....... of forests, grasslands and crops and 319 aquatic studies of phytoplankton, macrophyte and attached microalgal communities to test if specific differences existed between the communities. Maximum gross photosynthesis and photosynthetic efficiency were systematically higher in terrestrial than in aquatic...

A de novo designed monomeric, compact three helix bundle protein on a carbohydrate template

DEFF Research Database (Denmark)

Malik, Leila; Nygård, Jesper; Christensen, Niels Johan

2015-01-01

De novo design and chemical synthesis of proteins and of other artificial structures, which mimic them, is a central strategy for understanding protein folding and for accessing proteins with novel functions. We have previously described carbohydrates as templates for the assembly of artificial...... the template could facilitate protein folding. Here we report the design and synthesis of 3-helix bundle carboproteins on deoxy-hexopyranosides. The carboproteins were analyzed by CD, AUC, SAXS, and NMR, which revealed the formation of the first compact, and folded monomeric carboprotein distinctly different...

The larvae of congeneric gastropods showed differential responses to the combined effects of ocean acidification, temperature and salinity.

Science.gov (United States)

Zhang, Haoyu; Cheung, S G; Shin, Paul K S

2014-02-15

The tolerance and physiological responses of the larvae of two congeneric gastropods, the intertidal Nassarius festivus and subtidal Nassarius conoidalis, to the combined effects of ocean acidification (pCO2 at 380, 950, 1250 ppm), temperature (15, 30°C) and salinity (10, 30 psu) were compared. Results of three-way ANOVA on cumulative mortality after 72-h exposure showed significant interactive effects in which mortality increased with pCO2 and temperature, but reduced at higher salinity for both species, with higher mortality being obtained for N. conoidalis. Similarly, respiration rate of the larvae increased with temperature and pCO2 level for both species, with a larger percentage increase for N. conoidalis. Larval swimming speed increased with temperature and salinity for both species whereas higher pCO2 reduced swimming speed in N. conoidalis but not N. festivus. The present findings indicated that subtidal congeneric species are more sensitive than their intertidal counterparts to the combined effects of these stressors. Copyright © 2014 Elsevier Ltd. All rights reserved.

Parasitic gastropod bioerosion trace fossil on Cenomanian oysters from Le Mans, France and its ichnologic and taphonomic context

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Gérard Breton

2017-03-01

Full Text Available We describe and name Loxolenichnus stellatocinctus Breton and Wisshak igen. et isp. nov., a bioerosion trace fossil on an Upper Cenomanian oyster from Le Mans (France. This trace is attributed here to a parasitic gastropod. The characteristics of this ichnospecies are a combination of one or several, vertical or oblique, complete penetrations, and an asymmetrical attachment etching (fixichnion with a diagnostic set of stellate grooves increasingly distinct towards the margin of the trace. By including two former Oichnus ichnospecies, Loxolenichnus halo comb. nov. and Loxolenichnus taddei comb. nov., Oichnus, is now constrained to pure predation traces (praedichnia. The numerous oysters collected from the Marnes à Pycnodonte biauriculata Formation show associated epibionts and encrusters as well as borers and scrapers. Encrusters comprise 24 taxa while bioerosion trace fossils comprise 17 ichnotaxa ranging from very rare (< 0.1% to quite abundant (81%. The taphonomic history leading to an ex-situ condensation of these oysters is complex. Both the Gnathichnus and Entobia ichnofacies are represented on the shellgrounds, presumably alternatingly.

Triple Helix and European Union (EU Funding: The case of Latin America, especially Mexico and the Seventh European Framework Program

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Jürgen Haberleithner

2010-05-01

Full Text Available The following analysis not only seeks to develop new potential intervention models; it also aims to create a detailed analysis of the existing problems with regards to communication among the active participants of Triple Helix (especially in Mexico. The special situation in Latin America with regards to existing corruption, the unequal distribution of power between the government and the private sector, dependence on other economies and other social issues will be analysed in accordance with the main focus of the investigation. The subsequent linking of potential partners to the development of an initiative for submitting a future Triple Helix/FP7 project represent an important contribution to a longer-term perspective on the preceding investigation. The potential partnerships between Europe and Latin America (in addition to other possible world regions, such as, for example, Pacific Asia will create an initial project draft within the scope of the conference.

Impact of non-native terrestrial mammals on the structure of the terrestrial mammal food web of Newfoundland, Canada.

Directory of Open Access Journals (Sweden)

Justin S Strong

Full Text Available The island of Newfoundland is unique because it has as many non-native terrestrial mammals as native ones. The impacts of non-native species on native flora and fauna can be profound and invasive species have been identified as one of the primary drivers of species extinction. Few studies, however, have investigated the effects of a non-native species assemblage on community and ecosystem properties. We reviewed the literature to build the first terrestrial mammal food web for the island of Newfoundland and then used network analyses to investigate how the timing of introductions and trophic position of non-native species has affected the structure of the terrestrial mammal food web in Newfoundland. The first non-native mammals (house mouse and brown rat became established in Newfoundland with human settlement in the late 15th and early 16th centuries. Coyotes and southern red-backed voles are the most recent mammals to establish themselves on the island in 1985 and 1998, respectively. The fraction of intermediate species increased with the addition of non-native mammals over time whereas the fraction of basal and top species declined over time. This increase in intermediate species mediated by non-native species arrivals led to an overall increase in the terrestrial mammal food web connectance and generality (i.e. mean number of prey per predator. This diverse prey base and sources of carrion may have facilitated the natural establishment of coyotes on the island. Also, there is some evidence that the introduction of non-native prey species such as the southern red-backed vole has contributed to the recovery of the threatened American marten. Long-term monitoring of the food web is required to understand and predict the impacts of the diverse novel interactions that are developing in the terrestrial mammal food web of Newfoundland.

Genotoxicity of Nicotiana tabacum leaves on Helix aspersa.

Science.gov (United States)

da Silva, Fernanda R; Erdtmann, Bernardo; Dalpiaz, Tiago; Nunes, Emilene; Ferraz, Alexandre; Martins, Tales L C; Dias, Johny F; da Rosa, Darlan P; Porawskie, Marilene; Bona, Silvia; da Silva, Juliana

2013-07-01

Tobacco farmers are routinely exposed to complex mixtures of inorganic and organic chemicals present in tobacco leaves. In this study, we examined the genotoxicity of tobacco leaves in the snail Helix aspersa as a measure of the risk to human health. DNA damage was evaluated using the micronucleus test and the Comet assay and the concentration of cytochrome P450 enzymes was estimated. Two groups of snails were studied: one fed on tobacco leaves and one fed on lettuce (Lactuca sativa L) leaves (control group). All of the snails received leaves (tobacco and lettuce leaves were the only food provided) and water ad libitum. Hemolymph cells were collected after 0, 24, 48 and 72 h. The Comet assay and micronucleus test showed that exposure to tobacco leaves for different periods of time caused significant DNA damage. Inhibition of cytochrome P450 enzymes occurred only in the tobacco group. Chemical analysis indicated the presence of the alkaloid nicotine, coumarins, saponins, flavonoids and various metals. These results show that tobacco leaves are genotoxic in H. aspersa and inhibit cytochrome P450 activity, probably through the action of the complex chemical mixture present in the plant.

Genotoxicity of Nicotiana tabacum leaves on Helix aspersa

Directory of Open Access Journals (Sweden)

Fernanda R. da Silva

2013-01-01

Full Text Available Tobacco farmers are routinely exposed to complex mixtures of inorganic and organic chemicals present in tobacco leaves. In this study, we examined the genotoxicity of tobacco leaves in the snail Helix aspersa as a measure of the risk to human health. DNA damage was evaluated using the micronucleus test and the Comet assay and the concentration of cytochrome P450 enzymes was estimated. Two groups of snails were studied: one fed on tobacco leaves and one fed on lettuce (Lactuca sativa L leaves (control group. All of the snails received leaves (tobacco and lettuce leaves were the only food provided and water ad libitum. Hemolymph cells were collected after 0, 24, 48 and 72 h. The Comet assay and micronucleus test showed that exposure to tobacco leaves for different periods of time caused significant DNA damage. Inhibition of cytochrome P450 enzymes occurred only in the tobacco group. Chemical analysis indicated the presence of the alkaloid nicotine, coumarins, saponins, flavonoids and various metals. These results show that tobacco leaves are genotoxic in H. aspersa and inhibit cytochrome P450 activity, probably through the action of the complex chemical mixture present in the plant.

Steady-state configurations and dynamics of the MreB helix within bacteria

Science.gov (United States)

Rutenberg, Andrew; Allard, Jun

2007-03-01

We present a quantitative model of the actin-like MreB cytoskeleton that is present in many prokaryotes. Individual MreB polymers are bundled into a supra-molecular array to make up helical cables. The cell wall imposes constraint forces through a global elasticity model. With variational techniques and stochastic simulations we obtain relationships between observable quantities such as the pitch of the helix, the total abundance of MreB molecules, and the thickness of the MreB cables. We address changes expected with slow cell growth, as well as turnover dynamics that are relevant to FRAP studies. We also address polarized macromolecular trafficking along the MreB cables without motor proteins.

Multi-model analysis of terrestrial carbon cycles in Japan: reducing uncertainties in model outputs among different terrestrial biosphere models using flux observations

Science.gov (United States)

Ichii, K.; Suzuki, T.; Kato, T.; Ito, A.; Hajima, T.; Ueyama, M.; Sasai, T.; Hirata, R.; Saigusa, N.; Ohtani, Y.; Takagi, K.

2009-08-01

Terrestrial biosphere models show large uncertainties when simulating carbon and water cycles, and reducing these uncertainties is a priority for developing more accurate estimates of both terrestrial ecosystem statuses and future climate changes. To reduce uncertainties and improve the understanding of these carbon budgets, we investigated the ability of flux datasets to improve model simulations and reduce variabilities among multi-model outputs of terrestrial biosphere models in Japan. Using 9 terrestrial biosphere models (Support Vector Machine-based regressions, TOPS, CASA, VISIT, Biome-BGC, DAYCENT, SEIB, LPJ, and TRIFFID), we conducted two simulations: (1) point simulations at four flux sites in Japan and (2) spatial simulations for Japan with a default model (based on original settings) and an improved model (based on calibration using flux observations). Generally, models using default model settings showed large deviations in model outputs from observation with large model-by-model variability. However, after we calibrated the model parameters using flux observations (GPP, RE and NEP), most models successfully simulated seasonal variations in the carbon cycle, with less variability among models. We also found that interannual variations in the carbon cycle are mostly consistent among models and observations. Spatial analysis also showed a large reduction in the variability among model outputs, and model calibration using flux observations significantly improved the model outputs. These results show that to reduce uncertainties among terrestrial biosphere models, we need to conduct careful validation and calibration with available flux observations. Flux observation data significantly improved terrestrial biosphere models, not only on a point scale but also on spatial scales.

River Floodplains as Habitat and Bio-Corridors for Distribution of Land Snails: Their Past and Present

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Horáčková Jitka

2015-12-01

Full Text Available River floodplains of Czech rivers serve as refugia to woodland or hydrophilous gastropods, in current intensively agriculturally utilised, urbanised and largely fragmented landscape. This habitat often form one of the last refuge and replace the natural habitat of these species. River floodplains also represent linear bio-corridors in landscape and allow gastropods to spread through the landscape in both directions, up and down the stream. We showed based on available fossil mollusc successions that development of the floodplain mollusc fauna took place quite different way in various river floodplains, depending on their specifics and geographical location, because especially the ones situated in the chernozem area of the Czech Republic had very different history in comparison with those in higher altitudes. The species richness and composition of recent floodplain malacofauna arises from historical development of particular area/site and depends also on environmental factors such as an elevation, humidity gradient, vegetation type and its biomass, light conditions of the site and soil reaction. Recently, the invasive plants represent a serious problem for current floodplain ecosystems; species richness and abundances of terrestrial mollusc floodplain assemblages are changing due to their effect. The impact on gastropods is species-specific and was described for the following species: Impatiens glandulifera, Fallopia japonica subsp. japonica, F. sachalinensis, F. ×bohemica.

Coastal niches for terrestrial predators: a stable isotope study

Energy Technology Data Exchange (ETDEWEB)

Mellbrand, K.; Hamback, P.A., E-mail: peter.hamback@botan.su.se [Stockholm Univ., Dept. of Botany, Stockholm (Sweden)

2010-12-15

The purpose of this study was to identify the use of marine versus terrestrial food items by terrestrial arthropod predators on Baltic Sea shores. The inflow of marine nutrients in the area consists mainly of marine algal detritus and emerging aquatic insects (e.g., chironomids). Diets of coastal arthropods were examined using carbon and nitrogen stable isotope analysis in a two source mixing model. The results suggest that spiders are the terrestrial predators mainly utilizing nutrients and energy of marine origin on Baltic Sea shores, whereas insect predators such as beetles and heteropterans mainly utilize nutrients and energy derived from terrestrial sources, possibly owing to differences in hunting behaviour. That spiders are the predators which benefit the most from the marine inflow suggest that eventual effects of marine subsidies for the coastal ecosystem as a whole are likely mediated by spiders. (author)

Coastal niches for terrestrial predators: a stable isotope study

International Nuclear Information System (INIS)

Mellbrand, K.; Hamback, P.A.

2010-01-01

The purpose of this study was to identify the use of marine versus terrestrial food items by terrestrial arthropod predators on Baltic Sea shores. The inflow of marine nutrients in the area consists mainly of marine algal detritus and emerging aquatic insects (e.g., chironomids). Diets of coastal arthropods were examined using carbon and nitrogen stable isotope analysis in a two source mixing model. The results suggest that spiders are the terrestrial predators mainly utilizing nutrients and energy of marine origin on Baltic Sea shores, whereas insect predators such as beetles and heteropterans mainly utilize nutrients and energy derived from terrestrial sources, possibly owing to differences in hunting behaviour. That spiders are the predators which benefit the most from the marine inflow suggest that eventual effects of marine subsidies for the coastal ecosystem as a whole are likely mediated by spiders. (author)

Origin and evolution of life on terrestrial planets.

Science.gov (United States)

Brack, A; Horneck, G; Cockell, C S; Bérces, A; Belisheva, N K; Eiroa, Carlos; Henning, Thomas; Herbst, Tom; Kaltenegger, Lisa; Léger, Alain; Liseau, Réne; Lammer, Helmut; Selsis, Franck; Beichman, Charles; Danchi, William; Fridlund, Malcolm; Lunine, Jonathan; Paresce, Francesco; Penny, Alan; Quirrenbach, Andreas; Röttgering, Huub; Schneider, Jean; Stam, Daphne; Tinetti, Giovanna; White, Glenn J

2010-01-01

The ultimate goal of terrestrial planet-finding missions is not only to discover terrestrial exoplanets inside the habitable zone (HZ) of their host stars but also to address the major question as to whether life may have evolved on a habitable Earth-like exoplanet outside our Solar System. We note that the chemical evolution that finally led to the origin of life on Earth must be studied if we hope to understand the principles of how life might evolve on other terrestrial planets in the Universe. This is not just an anthropocentric point of view: the basic ingredients of terrestrial life, that is, reduced carbon-based molecules and liquid H(2)O, have very specific properties. We discuss the origin of life from the chemical evolution of its precursors to the earliest life-forms and the biological implications of the stellar radiation and energetic particle environments. Likewise, the study of the biological evolution that has generated the various life-forms on Earth provides clues toward the understanding of the interconnectedness of life with its environment.

Terrestrial forest management plan for Palmyra Atoll

Science.gov (United States)

Hathaway, Stacie A.; McEachern, Kathryn; Fisher, Robert N.

2011-01-01

This 'Terrestrial Forest Management Plan for Palmyra Atoll' was developed by the U.S. Geological Survey (USGS) for The Nature Conservancy (TNC) Palmyra Program to refine and expand goals and objectives developed through the Conservation Action Plan process. It is one in a series of adaptive management plans designed to achieve TNC's mission toward the protection and enhancement of native wildlife and habitat. The 'Terrestrial Forest Management Plan for Palmyra Atoll' focuses on ecosystem integrity and specifically identifies and addresses issues related to assessing the status and distribution of resources, as well as the pressures acting upon them, most specifically nonnative and potentially invasive species. The plan, which presents strategies for increasing ecosystem integrity, provides a framework to implement and track the progress of conservation and restoration goals related to terrestrial resources on Palmyra Atoll. The report in its present form is intended to be an overview of what is known about historical and current forest resources; it is not an exhaustive review of all available literature relevant to forest management but an attempt to assemble as much information specific to Palmyra Atoll as possible. Palmyra Atoll is one of the Northern Line Islands in the Pacific Ocean southwest of the Hawai`ian Islands. It consists of many heavily vegetated islets arranged in a horseshoe pattern around four lagoons and surrounded by a coral reef. The terrestrial ecosystem consists of three primary native vegetation types: Pisonia grandis forest, coastal strand forest, and grassland. Among these vegetation types, the health and extent of Pisonia grandis forest is of particular concern. Overall, the three vegetation types support 25 native plant species (two of which may be extirpated), 14 species of sea birds, six shore birds, at least one native reptile, at least seven native insects, and six native land crabs. Green and hawksbill turtles forage at Palmyra Atoll

Innovative Development of Kazakhstan on The Basis of Triple Helix and Cluster Approach

Directory of Open Access Journals (Sweden)

Farkhat Musayevich Dnishev

2015-06-01

Full Text Available The aim of the research is to study the Triple Helix model feasibility in developing innovations and using cluster approach in Kazakhstan. There are possible points of the emergence of clusters in Kazakhstan. However, there are a lot of constraining factors. First of all, institutional and social factors: the culture of business, unfair competition, low trust of economic agents to each other and to power institutes, low psychological readiness for cooperation of the enterprises of various branches and regions, poor development of chambers of commerce, and industrial associations. For the time being, the majority of regions of Kazakhstan are characterized by a limited set of high technology industrial branches, and a sharp shortage of universities generating innovation and research institutes. The research results show that the open innovation model is realized in a limited scale that does not allow to export innovations into external markets, to participate in global technology chains and international research networks. At the same time, some interaction schemes and preconditions for the development of the Triple Helix model are emerging. However, in general, the innovation policy is not systemic; it does not unite actions in the sphere of science and technology, education, industry, and regional initiatives. As the result of the research, some policy implications are given. For the development of clusters in Kazakhstan, it is desirable to use such a way, as integration into global cluster networks. It is necessary to make use of foreign experience at which various specialized state agencies become participants of clusters. It is necessary to focus not only on science but also industry, which should play the central role in the innovation process.

Oxidation of Helix-3 methionines precedes the formation of PK resistant PrP.

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Tamar Canello

2010-07-01

Full Text Available While elucidating the peculiar epitope of the alpha-PrP mAb IPC2, we found that PrPSc exhibits the sulfoxidation of residue M213 as a covalent signature. Subsequent computational analysis predicted that the presence of sulfoxide groups at both Met residues 206 and 213 destabilize the alpha-fold, suggesting oxidation may facilitate the conversion of PrPC into PrPSc. To further study the effect of oxidation on prion formation, we generated pAbs to linear PrP peptides encompassing the Helix-3 region, as opposed to the non-linear complexed epitope of IPC2. We now show that pAbs, whose epitopes comprise Met residues, readily detected PrPC, but could not recognize most PrPSc bands unless they were vigorously reduced. Next, we showed that the alpha-Met pAbs did not recognize newly formed PrPSc, as is the case for the PK resistant PrP present in lines of prion infected cells. In addition, these reagents did not detect intermediate forms such as PK sensitive and partially aggregated PrPs present in infected brains. Finally, we show that PrP molecules harboring the pathogenic mutation E200K, which is linked to the most common form of familial CJD, may be spontaneously oxidized. We conclude that the oxidation of methionine residues in Helix-3 represents an early and important event in the conversion of PrPC to PrPSc. We believe that further investigation into the mechanism and role of PrP oxidation will be central in finally elucidating the mechanism by which a normal cell protein converts into a pathogenic entity that causes fatal brain degeneration.

Determination of the variability of both hydrophilic and lipophilic toxins in endemic wild bivalves and carnivorous gastropods from the southern part of Chile.

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Zamorano, Ruben; Marín, Michelle; Cabrera, Fabiola; Figueroa, Diego; Contreras, Cristóbal; Barriga, Andrés; Lagos, Néstor; García, Carlos

2013-01-01

The aim of this study was to analyse and determine the composition of paralytic shellfish poisoning (PSP) toxins and lipophilic toxins in the Region of Aysén, Chile, in wild endemic mussels (Mytilus chilensis, Venus antiqua, Aulacomya ater, Choromytilus chorus, Tagelus dombeii and Gari solida) and in two endemic carnivorous molluscs species (Concholepas concholepas and Argobuccinum ranelliforme). PSP-toxin contents were determined by using HPLC with fluorescence detection, while lipophilic toxins were determined by using LC-MS/MS. Mean concentrations for the total of PSP toxins were in the range 55-2505 μg saxitoxin-equivalent/100 g. The two most contaminated samples for PSP toxicity were bivalve Gari solida and carnivorous Argobuccinum ranelliforme with 2505 ± 101 and 1850 ± 137 μg saxitoxin-equivalent/100 g, respectively (p < 0.05). The lipophilic toxins identified were okadaic acid, dinophysistoxin-1 (DTX-1), azaspiracid-1 (AZA-1), pectenotoxin-2 (PTX-2) and yessotoxins (YTX). All analysed molluscs contained lipophilic toxins at levels ranging from 56 ± 4.8 to 156.1 ± 8.2 μg of okadaic acid-equivalent/kg shellfish together with YTX at levels ranging from 1.0 ± 0.1 to 18 ± 0.9 μg of YTX-equivalent/kg shellfish and AZA at levels ranging from 3.6 ± 0.2 to 31 ± 2.1 μg of AZA-equivalent/kg shellfish. Furthermore, different bivalves and gastropods differ in their capacity of retention of lipophilic toxins, as shown by the determination of their respective lipophilic toxins levels. In all the evaluated species, the presence of lipophilic toxins associated with biotransformation in molluscs and carnivorous gastropods was not identified, in contrast to the identification of PSP toxins, where the profiles identified in the different species are directly related to biotransformation processes. Thus, this study provides evidence that the concentration of toxins in the food intake of the evaluated species (Bivalvia and Gastropoda class) determines the degree of

Helix Nebula: Enabling federation of existing data infrastructures and data services to an overarching cross-domain e-infrastructure

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Lengert, Wolfgang; Farres, Jordi; Lanari, Riccardo; Casu, Francesco; Manunta, Michele; Lassalle-Balier, Gerard

2014-05-01

Helix Nebula has established a growing public private partnership of more than 30 commercial cloud providers, SMEs, and publicly funded research organisations and e-infrastructures. The Helix Nebula strategy is to establish a federated cloud service across Europe. Three high-profile flagships, sponsored by CERN (high energy physics), EMBL (life sciences) and ESA/DLR/CNES/CNR (earth science), have been deployed and extensively tested within this federated environment. The commitments behind these initial flagships have created a critical mass that attracts suppliers and users to the initiative, to work together towards an "Information as a Service" market place. Significant progress in implementing the following 4 programmatic goals (as outlined in the strategic Plan Ref.1) has been achieved: × Goal #1 Establish a Cloud Computing Infrastructure for the European Research Area (ERA) serving as a platform for innovation and evolution of the overall infrastructure. × Goal #2 Identify and adopt suitable policies for trust, security and privacy on a European-level can be provided by the European Cloud Computing framework and infrastructure. × Goal #3 Create a light-weight governance structure for the future European Cloud Computing Infrastructure that involves all the stakeholders and can evolve over time as the infrastructure, services and user-base grows. × Goal #4 Define a funding scheme involving the three stake-holder groups (service suppliers, users, EC and national funding agencies) into a Public-Private-Partnership model to implement a Cloud Computing Infrastructure that delivers a sustainable business environment adhering to European level policies. Now in 2014 a first version of this generic cross-domain e-infrastructure is ready to go into operations building on federation of European industry and contributors (data, tools, knowledge, ...). This presentation describes how Helix Nebula is being used in the domain of earth science focusing on geohazards. The

Triple-helix molecular switch-based aptasensors and DNA sensors.

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Bagheri, Elnaz; Abnous, Khalil; Alibolandi, Mona; Ramezani, Mohammad; Taghdisi, Seyed Mohammad

2018-07-15

Utilization of traditional analytical techniques is limited because they are generally time-consuming and require high consumption of reagents, complicated sample preparation and expensive equipment. Therefore, it is of great interest to achieve sensitive, rapid and simple detection methods. It is believed that nucleic acids assays, especially aptamers, are very important in modern life sciences for target detection and biological analysis. Aptamers and DNA-based sensors have been widely used for the design of various sensors owing to their unique features. In recent years, triple-helix molecular switch (THMS)-based aptasensors and DNA sensors have been broadly utilized for the detection and analysis of different targets. The THMS relies on the formation of DNA triplex via Watson-Crick and Hoogsteen base pairings under optimal conditions. This review focuses on recent progresses in the development and applications of electrochemical, colorimetric, fluorescence and SERS aptasensors and DNA sensors, which are based on THMS. Also, the advantages and drawbacks of these methods are discussed. Copyright © 2018 Elsevier B.V. All rights reserved.