Antinociceptive effect of critoniella acuminata, physalis peruviana and salvia rubescens

OpenAIRE

Munóz, Carol; Vergel, Nadezdha E.; Aragón, Diana Marcela; Ospina, Luis Fernando

2010-01-01

Se evaluó el efecto antinociceptivo de extractos, fracciones y compuestos de Critoniella acuminata, Physalis peruviana y Salvia rubescens mediante los métodos de placa caliente, contorsiones abdominales inducidas por ácido acético y ensayo de la formalina. La fracción de Critoniella acuminata en dosis de 100 mg/kg p.o. presentó actividad antinociceptiva al aumentar el tiempo de reacción del animal ante la aplicación de un estímulo térmico (método de la placa caliente), mient...

Polar localization of plasma membrane Ca2+/Mg2+ ATPase correlates with the pattern of steady ionic currents in eggs ofLymnaea stagnalis andBithynia tentaculata (Mollusca).

Science.gov (United States)

Zivkovic, Danica; Créton, Robbert; Zwaan, Gideon; de Bruijn, Willem C; Dohmen, M René

1990-11-01

During extrusion of the first polar body in eggs ofLymnaea stagnalis andBithynia tentaculata a localized Ca 2+ /Mg 2+ ATPase activity was detected, using Ando's enzyme-cytochemical method for electron microscopy [Ando et al. (1981) Acta Histochem Cytochem 14:705-726]. The enzyme activity was distributed in a polar fashion, along the cytoplasmic face of the plasma membrane. In the eggs ofLymnaea it was found only in the vegetal hemisphere, whereas inBithynia eggs it was localized both in the vegetal hemisphere and at the animal pole. This pattern of enzyme activity corresponds to the polar pattern of transcellular ionic currents measured with the vibrating probe, which we showed to be partially carried or regulated by calcium [Zivkovic and Dohmen (1989) Biol Bull (Woods Hole) 176 (Suppl):103-109]. The characteristics of the ATPase were studied using a variety of approaches such as ion and substrate depletions and substitutions, addition of specific inhibitors of ATPase activity, treatment with EDTA/EGTA and electron energy-loss spectrometry. The results indicate that, inLymnaea, there are at least two enzymatic entities. The first one is a Ca 2+ /Mg 2+ ATPase localized along the membrane and in the cortex of the vegetal hemisphere. The second one is a Ca 2+ -stimulated ATPase (calcium pump of the plasma membrane) localized in a small region of the membrane at the vegetal pole. We speculate that in the eggs ofLymnaea andBithynia a functional relationship exists between the plasma-membrane-associated ATPase activity and the transcellular ionic currents measured in the same region.

Sub-lethal cadmium exposure increases phytochelatin concentrations in the aquatic snail Lymnaea stagnalis

Energy Technology Data Exchange (ETDEWEB)

SF, Gonçalves [Department of Biology & CESAM, Centre for Environmental and Marine Studies, University of Aveiro, 3810-193 Aveiro (Portugal); SK, Davies [Department of Surgery and Cancer, Imperial College London, Sir Alexander Fleming Building, London SW7 2AZ (United Kingdom); Bennett, M. [Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, London SW7 2AZ (United Kingdom); Raab, A.; Feldmann, J. [TESLA, Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland (United Kingdom); Kille, P. [Cardiff School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3US (United Kingdom); Loureiro, S. [Department of Biology & CESAM, Centre for Environmental and Marine Studies, University of Aveiro, 3810-193 Aveiro (Portugal); DJ, Spurgeon [Centre for Ecology and Hydrology, Maclean Building, Benson Lane, Wallingford OX10 8BB (United Kingdom); JG, Bundy, E-mail: j.bundy@imperial.ac.uk [Department of Surgery and Cancer, Imperial College London, Sir Alexander Fleming Building, London SW7 2AZ (United Kingdom)

2016-10-15

Phytochelatins are metal-binding metabolites found in almost all plant species and some animal groups, including nematodes and annelids, where they can play an important role in detoxifying metals such as cadmium. Species from several other taxa contain a phytochelatin synthase (PCS) gene orthologue, including molluscs, indicating they may have the potential to synthesize phytochelatins. However, the presence of a gene alone does not demonstrate that it plays a functional role in metal detoxification. In the present study, we show that the aquatic snail Lymnaea stagnalis produced both penta- and heptapeptide phytochelatins (i.e. phytochelatin-2 and phytochelatin-3), and their levels increased in response to sub-lethal levels of cadmium. - Highlights: • Little is known about the role of phytochelatins in metal detoxification in animals. • We detected phytochelatins (PC{sub 2} and PC{sub 3}) in a mollusc species, Lymnaea stagnalis. • Phytochelatins increased in Lymnaea stagnalis when exposed to cadmium. • Future research on phytochelatin responses in molluscs would be valuable.

Growth, physiological and biochemical responses of Camptotheca acuminata seedlings to different light environments

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Xiaohua eMa

2015-05-01

Full Text Available Light intensity critically affects plant growth. Camptotheca acuminata is a light-demanding species, but its optimum light intensity is not known. To investigate the response of C. acuminata seedlings to different light intensities, specifically 100% irradiance (PAR, 1500±30 μmol m-2 s-1, 75% irradiance, 50% irradiance, and 25% irradiance, a pot experiment was conducted to analyze growth parameters, photosynthetic pigments, gas exchange, chlorophyll fluorescence, stomatal structure and density, chloroplast ultrastructure, ROS concentrations, and antioxidant activities. Plants grown under 75% irradiance had significantly higher total biomass, seedling height, ground diameter, photosynthetic capacity, photochemical efficiency and photochemical quenching than those grown under 100%, 25%, and 50% irradiance. Malondialdehyde (MDA content, relative electrolyte conductivity (REC, superoxide anion (O2.- production, and peroxide (H2O2 content were lower under 75% irradiance. The less pronounced plant growth under 100% and 25% irradiance was associated with a decline in photosynthetic capacity and photochemical efficiency, with increases in the activity of specific antioxidants (i.e., superoxidase dismutase, peroxidase, and catalase, and with increases in MDA content and REC. Lower levels of irradiance were associated with significantly higher concentrations of chlorophyll (Chl a and b and lower Chla/b ratios. Stomatal development was most pronounced under 75% irradiance. Modification of chloroplast development was found to be an important mechanism of responding to different light intensities in C. acuminata. The results indicated that 75% irradiance is optimal for the growth of C. acuminata seedlings. The improvement in C. acuminata growth under 75% irradiance was attributable to increased photosynthesis, less accumulation of ROS, and the maintenance of the stomatal and chloroplast structure.

Evolution of the Banana Genome (Musa acuminata) Is Impacted by Large Chromosomal Translocations.

Science.gov (United States)

Martin, Guillaume; Carreel, Françoise; Coriton, Olivier; Hervouet, Catherine; Cardi, Céline; Derouault, Paco; Roques, Danièle; Salmon, Frédéric; Rouard, Mathieu; Sardos, Julie; Labadie, Karine; Baurens, Franc-Christophe; D'Hont, Angélique

2017-09-01

Most banana cultivars are triploid seedless parthenocarpic clones derived from hybridization between Musa acuminata subspecies and sometimes M. balbisiana. M. acuminata subspecies were suggested to differ by a few large chromosomal rearrangements based on chromosome pairing configurations in intersubspecies hybrids. We searched for large chromosomal rearrangements in a seedy M. acuminata ssp. malaccensis banana accession through mate-pair sequencing, BAC-FISH, targeted PCR and marker (DArTseq) segregation in its progeny. We identified a heterozygous reciprocal translocation involving two distal 3 and 10 Mb segments from chromosomes 01 and 04, respectively, and showed that it generated high segregation distortion, reduced recombination and linkage between chromosomes 01 and 04 in its progeny. The two chromosome structures were found to be mutually exclusive in gametes and the rearranged structure was preferentially transmitted to the progeny. The rearranged chromosome structure was frequently found in triploid cultivars but present only in wild malaccensis ssp. accessions, thus suggesting that this rearrangement occurred in M. acuminata ssp. malaccensis. We propose a mechanism for the spread of this rearrangement in Musa diversity and suggest that this rearrangement could have played a role in the emergence of triploid cultivars. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Ocorrência de infecção natural de Fasciola hepatica Linnaeus, 1758 em Lymnaea columella Say, 1817 no Vale do Paraíba, SP, Brasil Natural infection by Fasciola hepatica in Lymnaea columella in the Paraíba river valley, S. Paulo, Brazil

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Marlene Tiduko Ueta

1980-06-01

Full Text Available Foram registradas em Piquete, no vale do rio Paraíba do Sul (SP, Brasil, taxas de 1,22% e 0,14% de infecção natural em Lymnaea columella, por Fasciola hepatica. Em um único exemplar de Lymnaea columella dentre os 1.052 examinados, foram observadas rédias com xifidiocercárias, rédias com cercárias de Fasciola hepatica e metacercárias de Echinostomatidae.Infection rates of 1.22% and 0.14% were obtained in Lymnaea columella snails naturally infected by Fasciola hepatica. Samples of the snails were collected in Piquete, a municipality of Paraíba do Sul, a river valley area in the State of S. Paulo. Also observed was one of the 1052 specimen of the Lymnaea columella rediae which had xiphidiocercariae and rediae with Fasciola hepatica cercariae and metacercariae of Echinostomatidae.

Polar localization of plasma membrane Ca2+/Mg2+ ATPase correlates with the pattern of steady ionic currents in eggs of Lymnaea stagnalis and Bithynia tentaculata (Mollusca)

NARCIS (Netherlands)

D. Zivkovic (Dana); R. Créton (Robbert); G. Zwaan (Gideon); W.C. de Bruijn (Wim); M.R. Dohmen (M.René)

1990-01-01

textabstractDuring extrusion of the first polar body in eggs of Lymnaea stagnalis and Bithynia tentaculata a localized Ca2+ /Mg2+ ATPase activity was detected, using Ando's enzyme-cytochemical method for electron microscopy [Ando et al. (1981) Acta Histochem Cytochem 14:705-726]. The enzyme activity

Altered gene activity correlated with long-term memory formation of conditioned taste aversion in Lymnaea.

Science.gov (United States)

Azami, Sachiyo; Wagatsuma, Akiko; Sadamoto, Hisayo; Hatakeyama, Dai; Usami, Takeshi; Fujie, Manabu; Koyanagi, Ryo; Azumi, Kaoru; Fujito, Yutaka; Lukowiak, Ken; Ito, Etsuro

2006-11-15

The pond snail Lymnaea stagnalis is capable of learning conditioned taste aversion (CTA) and then consolidating that learning into long-term memory (LTM) that persists for at least 1 month. LTM requires de novo protein synthesis and altered gene activity. Changes in gene activity in Lymnaea that are correlated with, much less causative, memory formation have not yet been identified. As a first step toward rectifying this situation, we constructed a cDNA microarray with mRNAs extracted from the central nervous system (CNS) of Lymnaea. We then, using this microarray assay, identified genes whose activity either increased or decreased following CTA memory consolidation. We also identified genes whose expression levels were altered after inhibition of the cyclic AMP response element-binding protein (CREB) that is hypothesized to be a key transcription factor for CTA memory. We found that the molluscan insulin-related peptide II (MIP II) was up-regulated during CTA-LTM, whereas the gene encoding pedal peptide preprohormone (Pep) was down-regulated by CREB2 RNA interference. We next examined mRNAs of MIP II and Pep using real-time RT-PCR with SYBR Green. The MIP II mRNA level in the CNS of snails exhibiting "good" memory for CTA was confirmed to be significantly higher than that from the CNS of snails exhibiting "poor" memory. In contrast, there was no significant difference in expression levels of the Pep mRNA between "good" and "poor" performers. These data suggest that in Lymnaea MIP II may play a role in the consolidation process that forms LTM following CTA training.

Analysis of traumatic ulcer healing time under the treatment of the Mauli banana (Musa acuminata 25% stem extract gel

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Dewi Puspitasari

2017-03-01

Full Text Available ABSTRACT Introduction: Traumatic ulcer is one of oral disorders that often occur. The prevalence is quite high, between 3-24% of population. Therapy of traumatic ulcer is symptomatic. People usually use Aloe vera extract gel. Previous research showed that the Aloe vera gel is equivalent with ethanol extract of 25% Mauli banana (Musa acuminata stem in accelerating wound healing based on the number of macrophages and neovascular. The objective of the study is to find out the time difference of traumatic ulcer healing using 25% Musa acuminata stem extract gel compared to a gel containing Aloe vera extract. Methods: The research was post test design. Subjects were patients of Oral Medicine Installation in Gusti Hasan Aman Dental Hospital Banjarmasin with diagnosis of traumatic ulcer using completely random sampling method. Eight patients as samples were determined by the formula of Lemeshow. Results: there was no significant difference with p=0,724 (p>0,05 between healing time using Aloe vera gel and 25% Musa acuminata stem extract. Conclusion: At the concentration of 25% Musa acuminata stem extract gel concentration has the same healing time with Aloe vera gel, therefore can be recommended as a topical use for traumatic ulcer healing. Keywords: Musa acuminata stem, Healing time, Traumatic ulcer

The natural impact of banana inflorescences (Musa acuminata on human nutrition

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Catharina E. Fingolo

2012-12-01

Full Text Available Banana inflorescences are popularly known as 'navels,' and they are used in Brazil as nutritional complements. However, the nutritional value of banana inflorescences (male flowers and bracts has never been studied. Therefore, plant material of Musa acuminata, cultivar "ouro", was collected in Rio de Janeiro state, Brazil, and then submitted to chemical procedures to determine its nutritional composition. The experiment was arranged a completely randomized design and performed in triplicate. The sample composition analysis showed percentual average value for moisture, protein, fat and ash as 8.21, 14.50, 4.04 and 14.43, respectively. The dehydrated inflorescences were found to contain a significant nutritive complement based on their high content of potassium (5008.26 mg / 100 g and fiber 49.83% (lignin, cellulose and hemicelluloses revealing important functional and nutritional properties. In a parallel evaluation, the anatomical study revealed key elements for the recognition of Musa acuminata when reduced to fragments.Inflorescências de bananeira são popularmente conhecidas como "umbigos", e esses são usados no Brasil como complementos nutricionais. No entanto, o valor nutricional das inflorescências (flores masculinas e brácteas de bananeira nunca foi estudado. Portanto, o material vegetal de Musa acuminata cultivar "ouro" foi coletado no Rio de Janeiro, Brasil e, em seguida, submetido aos procedimentos químicos para determinar a sua composição nutricional. As análises foram realizadas em triplicata. A análise da composição da amostra apresentou teor percentual médio de umidade, proteína, lipídeos e cinza de 8,21, 14,50, 4,04 e 14,43, respectivamente. As inflorescências secas mostraram significativo complemento nutritivo baseado no alto conteúdo de potássio (5.008,26 mg / 100 g e de fibra 49,83% (lignina, celulose e hemiceluloses revelando importantes propriedades funcional e nutritiva. Em uma avaliação paralela, o estudo

Life-cycle stages of Dinophysis acuminata (Dinophyceae) in the ...

African Journals Online (AJOL)

Despite many observations of different life-cycle stages of Dinophysis species, the complete life history of the genus is still unknown owing to the difficulties encountered in culturing these species. The seasonal distribution of D. acuminata was followed at two offshore stations in the brackish Baltic Sea by means of in situ ...

Characterization of novel microsatellite markers in Musa acuminata subsp. burmannicoides, var. Calcutta 4

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Amorim Edson P

2010-05-01

Full Text Available Abstract Background Banana is a nutritionally important crop across tropical and sub-tropical countries in sub-Saharan Africa, Central and South America and Asia. Although cultivars have evolved from diploid, triploid and tetraploid wild Asian species of Musa acuminata (A genome and Musa balbisiana (B genome, many of today's commercial cultivars are sterile triploids or diploids, with fruit developing via parthenocarpy. As a result of restricted genetic variation, improvement has been limited, resulting in a crop frequently lacking resistance to pests and disease. Considering the importance of molecular tools to facilitate development of disease resistant genotypes, the objectives of this study were to develop polymorphic microsatellite markers from BAC clone sequences for M. acuminata subsp. burmannicoides, var. Calcutta 4. This wild diploid species is used as a donor cultivar in breeding programs as a source of resistance to diverse biotic stresses. Findings Microsatellite sequences were identified from five Calcutta 4 BAC consensi datasets. Specific primers were designed for 41 loci. Isolated di-nucleotide repeat motifs were the most abundant, followed by tri-nucleotides. From 33 tested loci, 20 displayed polymorphism when screened across 21 diploid M. acuminata accessions, contrasting in resistance to Sigatoka diseases. The number of alleles per SSR locus ranged from two to four, with a total of 56. Six repeat classes were identified, with di-nucleotides the most abundant. Expected heterozygosity values for polymorphic markers ranged from 0.31 to 0.75. Conclusions This is the first report identifying polymorphic microsatellite markers from M. acuminata subsp. burmannicoides, var. Calcutta 4 across accessions contrasting in resistance to Sigatoka diseases. These BAC-derived polymorphic microsatellite markers are a useful resource for banana, applicable for genetic map development, germplasm characterization, evolutionary studies and marker

Characterization of novel microsatellite markers in Musa acuminata subsp. burmannicoides, var. Calcutta 4.

Science.gov (United States)

Miller, Robert Ng; Passos, Marco An; Menezes, Natalia Np; Souza, Manoel T; do Carmo Costa, Marcos M; Rennó Azevedo, Vânia C; Amorim, Edson P; Pappas, Georgios J; Ciampi, Ana Y

2010-05-27

Banana is a nutritionally important crop across tropical and sub-tropical countries in sub-Saharan Africa, Central and South America and Asia. Although cultivars have evolved from diploid, triploid and tetraploid wild Asian species of Musa acuminata (A genome) and Musa balbisiana (B genome), many of today's commercial cultivars are sterile triploids or diploids, with fruit developing via parthenocarpy. As a result of restricted genetic variation, improvement has been limited, resulting in a crop frequently lacking resistance to pests and disease. Considering the importance of molecular tools to facilitate development of disease resistant genotypes, the objectives of this study were to develop polymorphic microsatellite markers from BAC clone sequences for M. acuminata subsp. burmannicoides, var. Calcutta 4. This wild diploid species is used as a donor cultivar in breeding programs as a source of resistance to diverse biotic stresses. Microsatellite sequences were identified from five Calcutta 4 BAC consensi datasets. Specific primers were designed for 41 loci. Isolated di-nucleotide repeat motifs were the most abundant, followed by tri-nucleotides. From 33 tested loci, 20 displayed polymorphism when screened across 21 diploid M. acuminata accessions, contrasting in resistance to Sigatoka diseases. The number of alleles per SSR locus ranged from two to four, with a total of 56. Six repeat classes were identified, with di-nucleotides the most abundant. Expected heterozygosity values for polymorphic markers ranged from 0.31 to 0.75. This is the first report identifying polymorphic microsatellite markers from M. acuminata subsp. burmannicoides, var. Calcutta 4 across accessions contrasting in resistance to Sigatoka diseases. These BAC-derived polymorphic microsatellite markers are a useful resource for banana, applicable for genetic map development, germplasm characterization, evolutionary studies and marker assisted selection for traits.

Physiological response to drought stress in Camptotheca acuminata seedlings from two provenances

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Yeqing eYing

2015-05-01

Full Text Available Drought stress is a key environmental factor limiting the growth and productivity of plants. The purpose of this study was to investigate the physiological responses of Camptotheca acuminata (C. acuminata to different drought stresses and compare the drought tolerance between the provenances Kunming (KM and Nanchang (NC, which are naturally distributed in different rainfall zones with annual rainfalls of 1000-1100 mm and 1600-1700 mm, respectively. We determined relative water content (RWC, chlorophyll content (Chl(a+b, net photosynthesis (Pn, gas exchange parameters, relative leakage conductivity (REC, malondialdehyde (MDA content and superoxide dismutase (SOD and peroxidase (POD activities of C. acuminata seedlings under both moderate (50% of maximum field capacity and severe drought stress (30% of maximum field capacity. As the degree of water stress increased, RWC, Chl(a+b content, Pn, stomatal conductance (Gs, transpiration rate (Tr and intercellular CO2 concentration (Ci values decreased, but water use efficiency (WUE, REC, MDA content and SOD and POD activities increased in provenances KM and NC. Under moderate and severe drought stress, provenance KM had higher RWC, Chl(a+b, Pn, WUE, SOD and POD and lower Gs, Tr, Ci and REC in leaves than provenance NC. The results indicated that provenance KM may maintain stronger drought tolerance via improvements in water-retention capacity, antioxidant enzyme activity and membrane integrity.

The Yerkes-Dodson law and appropriate stimuli for conditioned taste aversion in Lymnaea.

Science.gov (United States)

Ito, Etsuro; Yamagishi, Miki; Takigami, Satoshi; Sakakibara, Manabu; Fujito, Yutaka; Lukowiak, Ken

2015-02-01

The pond snail Lymnaea stagnalis can learn conditioned taste aversion and then consolidate it into long-term memory (LTM). A high-voltage electric shock was used as the unconditioned stimulus, where we have previously used KCl. We varied the strength of both the conditioned and unconditioned stimuli to determine whether the so-called Yerkes-Dodson law prevailed. This is an empirical relationship between the state of arousal and LTM formation, showing that there is an optimal level of arousal leading to memory formation. However, too little or too much arousal results in poorer LTM. We found here that the most appropriate stimuli to use in taste aversion training in Lymnaea were a 10 mmol l(-1) sucrose solution as the conditioned stimulus and a 3 s electric shock as the unconditioned stimulus. © 2015. Published by The Company of Biologists Ltd.

Chemosensitivity of the osphradium of the pond snail Lymnaea stagnalis

Science.gov (United States)

Wedemeyer; Schild

1995-01-01

The osphradium of the pond snail Lymnaea stagnalis was studied to determine the stimuli to which this organ responds. The following stimuli were tested: hypoxia, hypercapnia, a mixture of amino acids, a mixture of citralva and amyl acetate and a mixture of lyral, lilial and ethylvanillin. The mean nerve activity consistently increased with elevated PCO2, whereas hypoxia produced variable effects. The nerve activity became rhythmic upon application of citralva and amyl acetate, but it increased in a non-rhythmic way upon application of the other two odorant mixtures tested. Whole-cell patch-clamp recordings were made from a group of 15 neurones that lay next to the issuing osphradial nerve, to determine whether ganglion cells were involved in olfactory signal processing. All neurones tested responded to at least one of the three mixtures of odorants. Both excitatory and inhibitory responses occurred. Our results indicate that the osphradium of the pond snail Lymnaea stagnalis is sensitive to elevated PCO2 as well as to three different classes of odorants. In addition, at least some neurones within the osphradium are involved in the processing of olfactory information.

Impairing DNA methylation obstructs memory enhancement for at least 24 hours in Lymnaea.

Science.gov (United States)

Rothwell, Cailin M; Lukowiak, Ken D

2017-01-01

Stressor-induced memory enhancement has previously been shown to involve DNA methylation in the mollusc Lymnaea stagnalis . Specifically, injection of the DNA methylation inhibitor 5-AZA one hour before exposure to a memory-enhancing stressor obstructs memory augmentation. However, the duration of the influence of 5-AZA on this memory enhancement has not yet been examined. In this study, 2 memory-enhancing stressors (a thermal stress and exposure to the scent of a predator) were used to examine whether injection of the DNA methylation inhibitor 5-AZA 24 hours before stress exposure would still impair memory enhancement. Indeed, it was observed that memory is still obstructed when 5-AZA is injected 24 hours before exposure to either of these stressors in Lymnaea . Understanding that 5-AZA still effectively impairs memory enhancement after a period of 24 hours is valuable because it indicates that experimental manipulations do not need to be made within one hour after the injection of this DNA methylation inhibitor and can instead be made within one day (i.e. 24 hours). These results will allow for a future examination of the possible involvement of DNA methylation in memory enhancement related to longer-term stressors or environmental changes. This study further elucidates the involvement of epigenetic changes in memory enhancement in Lymnaea , providing insight into the process of memory formation in this mollusc.

The natural impact of banana inflorescences (Musa acuminata) on human nutrition.

Science.gov (United States)

Fingolo, Catharina E; Braga, João M A; Vieira, Ana C M; Moura, Mirian R L; Kaplan, Maria Auxiliadora C

2012-12-01

Banana inflorescences are popularly known as 'navels,' and they are used in Brazil as nutritional complements. However, the nutritional value of banana inflorescences (male flowers and bracts) has never been studied. Therefore, plant material of Musa acuminata, cultivar "ouro", was collected in Rio de Janeiro state, Brazil, and then submitted to chemical procedures to determine its nutritional composition. The experiment was arranged a completely randomized design and performed in triplicate. The sample composition analysis showed percentual average value for moisture, protein, fat and ash as 8.21, 14.50, 4.04 and 14.43, respectively. The dehydrated inflorescences were found to contain a significant nutritive complement based on their high content of potassium (5008.26 mg / 100 g) and fiber 49.83% (lignin, cellulose and hemicelluloses) revealing important functional and nutritional properties. In a parallel evaluation, the anatomical study revealed key elements for the recognition of Musa acuminata when reduced to fragments.

A saturated SSR/DArT linkage map of Musa acuminata addressing genome rearrangements among bananas.

Science.gov (United States)

Hippolyte, Isabelle; Bakry, Frederic; Seguin, Marc; Gardes, Laetitia; Rivallan, Ronan; Risterucci, Ange-Marie; Jenny, Christophe; Perrier, Xavier; Carreel, Françoise; Argout, Xavier; Piffanelli, Pietro; Khan, Imtiaz A; Miller, Robert N G; Pappas, Georgios J; Mbéguié-A-Mbéguié, Didier; Matsumoto, Takashi; De Bernardinis, Veronique; Huttner, Eric; Kilian, Andrzej; Baurens, Franc-Christophe; D'Hont, Angélique; Cote, François; Courtois, Brigitte; Glaszmann, Jean-Christophe

2010-04-13

The genus Musa is a large species complex which includes cultivars at diploid and triploid levels. These sterile and vegetatively propagated cultivars are based on the A genome from Musa acuminata, exclusively for sweet bananas such as Cavendish, or associated with the B genome (Musa balbisiana) in cooking bananas such as Plantain varieties. In M. acuminata cultivars, structural heterozygosity is thought to be one of the main causes of sterility, which is essential for obtaining seedless fruits but hampers breeding. Only partial genetic maps are presently available due to chromosomal rearrangements within the parents of the mapping populations. This causes large segregation distortions inducing pseudo-linkages and difficulties in ordering markers in the linkage groups. The present study aims at producing a saturated linkage map of M. acuminata, taking into account hypotheses on the structural heterozygosity of the parents. An F1 progeny of 180 individuals was obtained from a cross between two genetically distant accessions of M. acuminata, 'Borneo' and 'Pisang Lilin' (P. Lilin). Based on the gametic recombination of each parent, two parental maps composed of SSR and DArT markers were established. A significant proportion of the markers (21.7%) deviated (p DArTs) covering 1197 cM. This first saturated map is proposed as a "reference Musa map" for further analyses. We also propose two complete parental maps with interpretations of structural rearrangements localized on the linkage groups. The structural heterozygosity in P. Lilin is hypothesized to result from a duplication likely accompanied by an inversion on another chromosome. This paper also illustrates a methodological approach, transferable to other species, to investigate the mapping of structural rearrangements and determine their consequences on marker segregation.

Central localization of plasticity involved in appetitive conditioning in Lymnaea

OpenAIRE

Straub, Volko A.; Styles, Benjamin J.; Ireland, Julie S.; O'Shea, Michael; Benjamin, Paul R.

2004-01-01

Learning to associate a conditioned (CS) and unconditioned stimulus (US) results in changes in the processing of CS information. Here, we address directly the question whether chemical appetitive conditioning of Lymnaea feeding behavior involves changes in the peripheral and/or central processing of the CS by using extracellular recording techniques to monitor neuronal activity at two stages of the sensory processing pathway. Our data show that appetitive conditioning does not affect signific...

Intraurethral condylomata acuminata associated with genital piercings.

Science.gov (United States)

Takahashi, S; Hirano, Y; Kawamura, T; Homma, Y

2013-01-01

A 33-year-old man was referred to our institution with papillary masses at the urethral meatus and difficulty urinating. Genital examination showed two piercings on the frenulum, which were penetrating the external urethra. Endoscopic examination revealed papillary tumours over the entire circumference of the penile urethra and the piercing site. The tumours were resected transurethrally. Microscopic examination revealed condylomata acuminata. Human papillomavirus types 6 and 66 were detected in the lesions. Retrograde urethral viral infection is rare because of the protection provided by the mucosal immune system. Genital piercing may have facilitated spread of the human papillomavirus into the urethra.

A saturated SSR/DArT linkage map of Musa acuminata addressing genome rearrangements among bananas

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Matsumoto Takashi

2010-04-01

Full Text Available Abstract Background The genus Musa is a large species complex which includes cultivars at diploid and triploid levels. These sterile and vegetatively propagated cultivars are based on the A genome from Musa acuminata, exclusively for sweet bananas such as Cavendish, or associated with the B genome (Musa balbisiana in cooking bananas such as Plantain varieties. In M. acuminata cultivars, structural heterozygosity is thought to be one of the main causes of sterility, which is essential for obtaining seedless fruits but hampers breeding. Only partial genetic maps are presently available due to chromosomal rearrangements within the parents of the mapping populations. This causes large segregation distortions inducing pseudo-linkages and difficulties in ordering markers in the linkage groups. The present study aims at producing a saturated linkage map of M. acuminata, taking into account hypotheses on the structural heterozygosity of the parents. Results An F1 progeny of 180 individuals was obtained from a cross between two genetically distant accessions of M. acuminata, 'Borneo' and 'Pisang Lilin' (P. Lilin. Based on the gametic recombination of each parent, two parental maps composed of SSR and DArT markers were established. A significant proportion of the markers (21.7% deviated (p Conclusions We propose a synthetic map with 11 linkage groups containing 489 markers (167 SSRs and 322 DArTs covering 1197 cM. This first saturated map is proposed as a "reference Musa map" for further analyses. We also propose two complete parental maps with interpretations of structural rearrangements localized on the linkage groups. The structural heterozygosity in P. Lilin is hypothesized to result from a duplication likely accompanied by an inversion on another chromosome. This paper also illustrates a methodological approach, transferable to other species, to investigate the mapping of structural rearrangements and determine their consequences on marker

Analysis of the leaf transcriptome of Musa acuminata during interaction with Mycosphaerella musicola: gene assembly, annotation and marker development.

Science.gov (United States)

Passos, Marco A N; de Cruz, Viviane Oliveira; Emediato, Flavia L; de Teixeira, Cristiane Camargo; Azevedo, Vânia C Rennó; Brasileiro, Ana C M; Amorim, Edson P; Ferreira, Claudia F; Martins, Natalia F; Togawa, Roberto C; Júnior, Georgios J Pappas; da Silva, Orzenil Bonfim; Miller, Robert N G

2013-02-05

Although banana (Musa sp.) is an important edible crop, contributing towards poverty alleviation and food security, limited transcriptome datasets are available for use in accelerated molecular-based breeding in this genus. 454 GS-FLX Titanium technology was employed to determine the sequence of gene transcripts in genotypes of Musa acuminata ssp. burmannicoides Calcutta 4 and M. acuminata subgroup Cavendish cv. Grande Naine, contrasting in resistance to the fungal pathogen Mycosphaerella musicola, causal organism of Sigatoka leaf spot disease. To enrich for transcripts under biotic stress responses, full length-enriched cDNA libraries were prepared from whole plant leaf materials, both uninfected and artificially challenged with pathogen conidiospores. The study generated 846,762 high quality sequence reads, with an average length of 334 bp and totalling 283 Mbp. De novo assembly generated 36,384 and 35,269 unigene sequences for M. acuminata Calcutta 4 and Cavendish Grande Naine, respectively. A total of 64.4% of the unigenes were annotated through Basic Local Alignment Search Tool (BLAST) similarity analyses against public databases.Assembled sequences were functionally mapped to Gene Ontology (GO) terms, with unigene functions covering a diverse range of molecular functions, biological processes and cellular components. Genes from a number of defense-related pathways were observed in transcripts from each cDNA library. Over 99% of contig unigenes mapped to exon regions in the reference M. acuminata DH Pahang whole genome sequence. A total of 4068 genic-SSR loci were identified in Calcutta 4 and 4095 in Cavendish Grande Naine. A subset of 95 potential defense-related gene-derived simple sequence repeat (SSR) loci were validated for specific amplification and polymorphism across M. acuminata accessions. Fourteen loci were polymorphic, with alleles per polymorphic locus ranging from 3 to 8 and polymorphism information content ranging from 0.34 to 0.82. A large set

Synaptic metaplasticity underlies tetanic potentiation in Lymnaea: a novel paradigm.

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Anita Mehta

Full Text Available We present a mathematical model that explains and interprets a novel form of short-term potentiation, which was found to be use-, but not time-dependent, in experiments done on Lymnaea neurons. The high degree of potentiation is explained using a model of synaptic metaplasticity, while the use-dependence (which is critically reliant on the presence of kinase in the experiment is explained using a model of a stochastic and bistable biological switch.

Climate Variability and Oceanographic Settings Associated with Interannual Variability in the Initiation of Dinophysis acuminata Blooms

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Henrick Berger

2013-08-01

Full Text Available In 2012, there were exceptional blooms of D. acuminata in early spring in what appeared to be a mesoscale event affecting Western Iberia and the Bay of Biscay. The objective of this work was to identify common climatic patterns to explain the observed anomalies in two important aquaculture sites, the Galician Rías Baixas (NW Spain and Arcachon Bay (SW France. Here, we examine climate variability through physical-biological couplings, Sea Surface Temperature (SST anomalies and time of initiation of the upwelling season and its intensity over several decades. In 2012, the mesoscale features common to the two sites were positive anomalies in SST and unusual wind patterns. These led to an atypical predominance of upwelling in winter in the Galician Rías, and increased haline stratification associated with a southward advection of the Gironde plume in Arcachon Bay. Both scenarios promoted an early phytoplankton growth season and increased stability that enhanced D. acuminata growth. Therefore, a common climate anomaly caused exceptional blooms of D. acuminata in two distant regions through different triggering mechanisms. These results increase our capability to predict intense diarrhetic shellfish poisoning outbreaks in the early spring from observations in the preceding winter.

Musculature of Notholca acuminata (Rotifera : Ploima : Brachionidae) revealed by confocal scanning laser microscopy

DEFF Research Database (Denmark)

Sørensen, M.V.; Funch, P.; Hooge, M.

2003-01-01

The body-wall and visceral musculature of Notholca acuminata was visualized using phalloidin-linked fluorescent dye under confocal laser scanning microscopy. The body-wall musculature includes dorsal, lateral, and ventral pairs of longitudinally oriented body retractor muscles, two pairs of head...

Sensory input from the osphradium modulates the response to memory-enhancing stressors in Lymnaea stagnalis.

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Karnik, Vikram; Braun, Marvin; Dalesman, Sarah; Lukowiak, Ken

2012-02-01

In the freshwater environment species often rely on chemosensory information to modulate behavior. The pond snail, Lymnaea stagnalis, is a model species used to characterize the causal mechanisms of long-term memory (LTM) formation. Chemical stressors including crayfish kairomones and KCl enhance LTM formation (≥24 h) in Lymnaea; however, how these stressors are sensed and the mechanism by which they affect the electrophysiological properties of neurons necessary for memory formation are poorly understood. Here, we assessed whether the osphradium, a primary chemosensory organ in Lymnaea, modulates LTM enhancement. To test this we severed the osphradial nerve proximal to the osphradium, using sham-operated animals as controls, and assessed the behavioral and electrophysiological response to crayfish kairomones and KCl. We operantly conditioned aerial respiratory behavior in intact, sham and osphradially cut animals, and tested for enhanced memory formation after exposure to the chemical stressors. Sham-operated animals displayed the same memory enhancement as intact animals but snails with a severed osphradial nerve did not show LTM enhancement. Extracellular recordings made from the osphradial nerve demonstrate that these stressors evoked afferent sensory activity. Intracellular recordings from right pedal dorsal 1 (RPeD1), a neuron necessary for LTM formation, demonstrate that its electrophysiological activity is altered by input from the osphradium following exposure to crayfish kairomones or KCl in sham and intact animals but no response is seen in RPeD1 in osphradially cut animals. Therefore, sensory input from the osphradium is necessary for LTM enhancement following exposure to these chemical stressors.

Antifungal constituents in alnus acuminata H.B.K. nodules Constituyentes antifungicos en nódulos radicales de Alnus Acuminata H.B.K.

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Gonzalez Jaime

1988-12-01

Full Text Available Alnus acuminata. H.B.K. is a native specimen of economic importance. that is characterized for having root nodules
that can fix nitrogen. The nodules chemical composition has not been sstablished, but, it has been seen that it has influence over the soil microflora. In order to establish the chemical composition and the activity of the obtained fractions, there were made extractions of the alder nodules. The insulated compounds were; xylose and ribose; an aromatic carboxylicaeid, an fatty aeid, an phenolic biarylheptanoid and a flavonoid glycosic. were also founded. The Fusarium oxysporum and Pythium sp. growing was inhibited by this last one sustance.Alnus acuminata. H.B.K. es una especie nativa de importancia económica que se caracteriza por tener nódulos radicales
fijadores de nitrógeno. La composición química de los nódulos no se ha establecido; sin embargo, se ha observado que actúa sobre la microflora del suelo. Con el fin de establecer la composición química de las fracciones obtenidas, se.realizaron extracciones a partir de nódulos de Aliso. Los compuestos
aislados 'fueron: xilosa y ribosa; además se caracterizaron un ácido carboxílico aromático, un ácido graso, un biariheptanoide
fenólico y un glicósido de flavonoide. Esta última sustancia inhibió el crecimiento de Fusarium oxvsporum y Pythium sp.

Condyloma acuminata in child end laser therapy: a case report

OpenAIRE

Ferizi, Mybera; Gercari, Antigona; Pajaziti, Laura; Blyta, Ymrane; Kocinaj, Allma; Dobruna, Shkendije

2009-01-01

Background Condyloma acuminata are soft, skin colored, fleshy warts that are caused by the Human Papilloma Virus (HPV). The disease is highly contagious, can appear singly or in groups, small or large. The incubation period may be from 1?6 months. Although anogenital warts are considered to be sexually transmitted in adults, this may not be the case for children. Genital warts in children may result from several modes of transmission: from the maternal genital tract autoinoculation, from fing...

Pituitary adenylate cyclase activating polypeptide (PACAP) and its receptors are present and biochemically active in the central nervous system of the pond snail Lymnaea stagnalis.

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Pirger, Zsolt; Laszlo, Zita; Hiripi, Laszlo; Hernadi, Laszlo; Toth, Gabor; Lubics, Andrea; Reglodi, Dora; Kemenes, Gyorgy; Mark, Laszlo

2010-11-01

PACAP is a highly conserved adenylate cyclase (AC) activating polypeptide, which, along with its receptors (PAC1-R, VPAC1, and VPAC2), is expressed in both vertebrate and invertebrate nervous systems. In vertebrates, PACAP has been shown to be involved in associative learning, but it is not known if it plays a similar role in invertebrates. To prepare the way for a detailed investigation into the possible role of PACAP and its receptors in a suitable invertebrate model of learning and memory, here, we undertook a study of their expression and biochemical role in the central nervous system of the pond snail Lymnaea stagnalis. Lymnaea is one of the best established invertebrate model systems to study the molecular mechanisms of learning and memory, including the role of cyclic AMP-activated signaling mechanisms, which crucially depend on the learning-induced activation of AC. However, there was no information available on the expression of PACAP and its receptors in sensory structures and central ganglia of the Lymnaea nervous system known to be involved in associative learning or whether or not PACAP can actually activate AC in these ganglia. Here, using matrix-assisted laser desorption ionization time of flight (MALDI-TOF) and immunohistochemistry, we established the presence of PACAP-like peptides in the cerebral ganglia and the lip region of Lymnaea. The MALDI-TOF data indicated an identity with mammalian PACAP-27 and the presence of a squid-like PACAP-38 highly homologous to vertebrate PACAP-38. We also showed that PACAP, VIP, and maxadilan stimulated the synthesis of cAMP in Lymnaea cerebral ganglion homogenates and that this effect was blocked by the appropriate general and selective PACAP receptor antagonists.

Metabolomic Profiles of Dinophysis acuminata and Dinophysis acuta Using Non-Targeted High-Resolution Mass Spectrometry: Effect of Nutritional Status and Prey

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María García-Portela

2018-04-01

Full Text Available Photosynthetic species of the genus Dinophysis are obligate mixotrophs with temporary plastids (kleptoplastids that are acquired from the ciliate Mesodinium rubrum, which feeds on cryptophytes of the Teleaulax-Plagioselmis-Geminigera clade. A metabolomic study of the three-species food chain Dinophysis-Mesodinium-Teleaulax was carried out using mass spectrometric analysis of extracts of batch-cultured cells of each level of that food chain. The main goal was to compare the metabolomic expression of Galician strains of Dinophysis acuminata and D. acuta that were subjected to different feeding regimes (well-fed and prey-limited and feeding on two Mesodinium (Spanish and Danish strains. Both Dinophysis species were able to grow while feeding on both Mesodinium strains, although differences in growth rates were observed. Toxin and metabolomic profiles of the two Dinophysis species were significantly different, and also varied between different feeding regimes and different prey organisms. Furthermore, significantly different metabolomes were expressed by a strain of D. acuminata that was feeding on different strains of the ciliate Mesodinium rubrum. Both species-specific metabolites and those common to D. acuminata and D. acuta were tentatively identified by screening of METLIN and Marine Natural Products Dictionary databases. This first metabolomic study applied to Dinophysis acuminata and D.acuta in culture establishes a basis for the chemical inventory of these species.

Isolation of MA-ACS Gene Family and Expression Study of MA-ACS1 Gene in Musa acuminata Cultivar Pisang Ambon Lumut

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LISTYA UTAMI KARMAWAN

2009-03-01

Full Text Available Musa acuminata cultivar pisang ambon lumut is a native climacteric fruit from Indonesia. Climacteric fruit ripening process is triggered by the gaseous plant hormone ethylene. The rate limiting enzyme involved in ethylene biosynthesis is ACC synthase (ACS which is encoded by ACS gene family. The objective of this study is to identify MA-ACS gene family in M. acuminata cultivar pisang ambon lumut and to study the MA-ACS1 gene expression. The result showed that there were nine M. acuminata ACS gene family members called MA-ACS1–9. Two of them (MA-ACS1 and MA-ACS2 were assessed using reverse transcriptase PCR (RT-PCR for gene expression study and it was only MA-ACS1 correlated with fruit ripening. The MA-ACS1 gene fragment has been successfully isolated and characterized and it has three introns, four exons, and one stop codon. It also shows highest homology with MACS1 gene from M. acuminata cultivar Hsian Jien Chiao (GenBank accession number AF056164. Expression analysis of MA-ACS1 using quantitative PCR (qPCR showed that MA-ACS1 gene expression increased significantly in the third day, reached maximum at the fifth day, and then decreased in the seventh day after harvesting. The qPCR expression analysis result correlated with the result of physical analysis during fruit ripening.

Antitumor Effects and Biological Mechanism of Action of the Aqueous Extract of the Camptotheca acuminata Fruit in Human Endometrial Carcinoma Cells

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Chi-Shian Lin

2014-01-01

Full Text Available The aqueous extracts of the leaves and fruit of Camptotheca acuminata have long been used in traditional Chinese medicine (TCM for treating cancer patients. The chemotherapeutic drug, camptothecin (CPT, and related analogs were first isolated from C. acuminata in the 1970s. Although the antitumor effects of CPT have been characterized in recent years, the antitumor effects of aqueous extracts of C. acuminata have not been clarified. The aims of our current study were to determine the tumor-suppression efficiency of an aqueous extract of the fruit of C. acuminata (AE-CA in the human endometrial carcinoma cell lines, HEC-1A, HEC-1B, and KLE, and compare its antitumor effects with those of CPT. Cell viability assays indicated that a dosage of AE-CA containing 0.28 mg/mL of CPT demonstrated enhanced cytotoxicity, compared with CPT treatment. The effects of AE-CA on the induction of cell cycle arrest, the accumulation of cyclin-A2 and -B1, and the activation of caspase-3 and caspase-7 were similar to those of CPT. Furthermore, AE-CA exhibited a synergistic effect on the cytotoxicity of cisplatin in HEC-1A and HEC-1B cells. These results indicated that AE-CA is a potent antitumor agent and can be combined with cisplatin for the treatment of human endometrial cancer.

Metabolomic Profiles of Dinophysis acuminata and Dinophysis acuta Using Non-Targeted High-Resolution Mass Spectrometry: Effect of Nutritional Status and Prey.

Science.gov (United States)

García-Portela, María; Reguera, Beatriz; Sibat, Manoella; Altenburger, Andreas; Rodríguez, Francisco; Hess, Philipp

2018-04-26

Photosynthetic species of the genus Dinophysis are obligate mixotrophs with temporary plastids (kleptoplastids) that are acquired from the ciliate Mesodinium rubrum , which feeds on cryptophytes of the Teleaulax-Plagioselmis-Geminigera clade. A metabolomic study of the three-species food chain Dinophysis-Mesodinium-Teleaulax was carried out using mass spectrometric analysis of extracts of batch-cultured cells of each level of that food chain. The main goal was to compare the metabolomic expression of Galician strains of Dinophysis acuminata and D. acuta that were subjected to different feeding regimes (well-fed and prey-limited) and feeding on two Mesodinium (Spanish and Danish) strains. Both Dinophysis species were able to grow while feeding on both Mesodinium strains, although differences in growth rates were observed. Toxin and metabolomic profiles of the two Dinophysis species were significantly different, and also varied between different feeding regimes and different prey organisms. Furthermore, significantly different metabolomes were expressed by a strain of D. acuminata that was feeding on different strains of the ciliate Mesodinium rubrum . Both species-specific metabolites and those common to D. acuminata and D. acuta were tentatively identified by screening of METLIN and Marine Natural Products Dictionary databases. This first metabolomic study applied to Dinophysis acuminata and D.acuta in culture establishes a basis for the chemical inventory of these species.

Potential roles of fish, birds, and water in swamp privet (Forestiera acuminata) seed dispersal

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Susan B. Adams; Paul B. Hamel; Kristina Connor; Bryce Burke; Emile S. Gardiner; David Wise

2007-01-01

Forestiera acuminata (swamp privet) is a common wetland shrub/small tree native to the southeastern United States. We examined several possible dispersal avenues for the plant. We tested germination of seeds exposed to various treatments, including passage through Ictalurus punctatus (Channel Catfi sh) guts, and conducted other...

Improvement of the banana "Musa acuminata" reference sequence using NGS data and semi-automated bioinformatics methods

Czech Academy of Sciences Publication Activity Database

Martin, G.; Baurens, F.C.; Droc, G.; Rouard, M.; Cenci, A.; Kilian, A.; Hastie, A.; Doležel, Jaroslav; Aury, J. M.; Alberti, A.; Carreel, F.; D'Hont, A.

2016-01-01

Roč. 17, MAR 16 (2016), s. 243 ISSN 1471-2164 Institutional support: RVO:61389030 Keywords : Musa acuminata * Genome assembly * Bioinformatics tool Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.729, year: 2016

EXTRACTION AND QUANTITATIVE DETERMINATION OF ASCORBIC ACID FROM BANANA PEEL MUSA ACUMINATA ‘KEPOK’

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Khairul Anwar Mohamad Said

2016-04-01

Full Text Available This paper discusses the extraction of an antioxidant compound, which is ascorbic acid or vitamin C, from a banana peel using an ultrasound-assisted extraction (UAE method. The type of banana used was Musa acuminata also known as “PisangKepok” in Malaysia. The investigation includes the effect of solvent/solid ratio (4.5, 5 g and 10  ml/g, sonication time (15, 30 and 45 mins and temperature variation (30 , 45  and 60oC on the extraction of ascorbic acid compounds from the banana peel to determine the best or optimum condition of the operation. Out of all extract samples analyzed by redox titration method using iodine solution, it was found that the highest yield was 0.04939 ± 0.00080 mg that resulted from an extraction at 30oC for 15 mins with 5 ml/g solvent-to-solute ratio.KEYWORDS:  Musa acuminata; ultrasound-assisted extraction; vitamin C; redox titration

Lymnaea viatrix and Lymnaea columella in the neotropical region: a distributional outline

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W. Lobato Paraense

1982-06-01

Full Text Available A review of lymnaeid samples collected by the author from 106 localities in Mexico, Cuba, Jamaica, Haiti, Dominican Republic, Puerto Rico, Martinique, Saint Lucia, Guatemala, Costa Rica, Panamá, Ecuador, Peru, Bolivia, Chile, Argentina, Uruguay andBrazil showed that one of them (from Ecuador belonged to Lymnaea cousini Jousseaume, 1887, and all the others to either L. viatrix Orbigny, 1835 or l. columella Say, 1817. The ranges of L. viatrix and L. columella overlap in Middle America, and in northern and southern South America (Venezuela-Colombia-Ecuador and northeastern Argentina-Uruguay-southernmost Brazil, respectively. L. viatrix was the only species found in Peru west of the Andes and in Chile, and is supposed to have migrated eastward to Argentina via the Negro river basin. The range of L. columella in South America is discontinuous. The species has been recorded from Venezuela, Colombia and Ecuador and, east of the Andes, from latitudes 15º S (central-west Brazil to 35º S (La Plata, Argentina. Such a gap may be attributed to either introduction from the northern into the southern area, or migration along the unsampled region on the eastern side of the Andes, or extinction in the now vacant area. No lymnaeids have been found so far in Brazil north of latitude 15º S and in the Guianas.A revisão de amostras de limneídeos coletados pelo autor em 106 localidades no México, Cuba, Jamaica, Haiti, República Dominicana, Porto Rico, Martinica, Santa Lúcia, Guatemala, Costa Rica, Panamá, Equador, Peru, Bolívia, Chile, Argentina, Uruguai e Brasil mostrou que uma delas (do Equador pertencia a Lymnaea cousini Jousseaume, 1887, e que todas as outras pertenciam a L. viatrix Orbigny, 1835 ou a L. columella Say, 1817. As distribuições da L. viatrix e da l. columella sobrepõem-se na Meso-América e na América do Sul setentrional (Venezuela-Colômbia-Equador e meridional (nordeste da Argentina-Uruguai-extremo sul do Brasil. A L. viatrix foi a

Diet quality affects chemical tolerance in the freshwater snail Lymnaea stagnalis.

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Fidder, Bridgette N; Reátegui-Zirena, Evelyn G; Salice, Christopher J

2018-04-01

Organisms generally select high-quality diets to obtain maximal energy while devoting the least amount of time and energy. Diets, however, can vary in natural systems. In ecotoxicological testing, the effect of diet type on organismal responses to toxicants has not been explored despite the potential for dietary effects to influence toxicological endpoints. We first evaluated diet quality using growth rate and sensitivity to the fungicide pyraclostrobin of Lymnaea stagnalis fed lettuce (common laboratory diet), turtle pellets (high nutrient composition), and a combination diet of both food items. We also measured the macronutrient content of snails raised on the multiple diets to determine how diet may have impacted energy allocation patterns. Finally, we evaluated whether snails discernibly preferred a particular diet. Snails fed high-nutrient and combination diets grew larger overall than snails fed a lettuce-only diet. Snails fed the high-nutrient and combination diets, both juvenile and adult, were significantly more tolerant to pyraclostrobin than snails fed lettuce. When measured for macronutrient content, snails raised on high-nutrient and combination diets had significantly higher carbohydrate content than snails fed lettuce. Despite the strong effects of diet type, snails did not exhibit a clear diet choice in preference trials. Dietary composition clearly influences growth rate, sensitivity, and macronutrient content of Lymnaea stagnalis. These results suggest that the nutritional environment has potentially strong impacts on toxicant sensitivity. Environ Toxicol Chem 2018;37:1158-1167. © 2017 SETAC. © 2017 SETAC.

Lymnaea columella: two new Brazilian localities in the states of Amazonas and Bahia

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W. Lobato Paraense

1986-03-01

Full Text Available The occurrence of Lymnaea columella is recorded in Tefé, Amazonas state, where it was found together with Drepanotrema anatinum, Physa marmorata and pomacea sp. L. columella was also collected in Salvador, Bahia state, at the dique do Tororó, an urban lake formely mentioned (as "lac Baril" by Moricand (1853 as a breeding-place of Biomphalaria glabrata, Drepanotrema cimex, D. depressissimum, Pomacea lineata, P. decussata and Ancylus moricandi. The four first-mentioned species, as well as physa cubensis and Hemisinus brasiliensis, were also collected now. This is the first record of a lymnaeid in the Northeastern region of Brazil.É registrada a ocorrência de Lymnaea columella em Tefé, Estado do Amazonas, onde foi encontrada juntamente com Physa marmorata e Pomacea sp. L. columella foi também coletada em Salvador, Estado da Bahia, no Dique do Tororó, lago urbano antes mencionado por Moricand (1853 como criadouro de Biomphalaria glabrata, Drepanotrema cimex, D. depressissimum, Pomacea lineata, P. decussata e Ancylus moricandi. As quatro primeiras espécies mencionadas, assim como Physa cubensis e Hemisinus brasiliensis, também foram agora coletadas. Este é o primeiro registro de um limneídeo na região Nordeste do Brasil

Peptidergic modulation of male sexual behavior in Lymnaea stagnalis: structural and functional characterization of -FVamide neuropeptides

NARCIS (Netherlands)

Smit, A.B.; van Kesteren, R.E.; van Minnen, J.; van Golen, F.A.; Jimenez, C.R.; Li, K.W.

2003-01-01

In the simultaneous hermaphrodite snail Lymnaea stagnalis, copulation as a male is controlled by neurons that send axons to the male copulatory organs via a single penis nerve. Using direct mass spectrometry of a penis nerve sample, we show that one of the molecular ions has a mass corresponding to

Condyloma acuminata in a 3-year-old female: Sexual abuse or not?

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Alia Abbas Rizvi

2016-01-01

Full Text Available Condyloma acuminata (also known as anogenital warts or venereal warts a sexually transmitted disease (STD is usually seen in younger adults. However, genital warts have been reported in all age groups of children including infants. The possibility of sexual abuse is a major concern in the evaluation of children with genital warts. We hereby report a case of genital warts in a three year old female child.

Progression of Intravesical Condyloma Acuminata to Locally Advanced Poorly Differentiated Squamous Cell Carcinoma

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A. Khambati

2016-07-01

Full Text Available Condyloma acuminata (CA is a common sexually transmitted disease caused by Human Papilloma Virus (HPV infection. CA of the bladder, however, is an exceedingly rare lesion. We present a rare case of poorly differentiated locally invasive squamous cell carcinoma (SCC arising from recurrent CA of the bladder in an immunocompetent patient and discuss pathophysiology and management of this unusual condition.

Effect of surface coating on ripening and early peel spotting in 'Sucrier' banana (Musa acuminata)

NARCIS (Netherlands)

Promyou, S.; Ketsa, S.; Doorn, van W.G.

2007-01-01

Sucrier¿ bananas (Musa acuminata, AA Group) show peel spotting when the peel is just about as yellow as green, which coincides with optimum eating quality. As consumers might relate the spotting to overripe fruit, early spotting is considered undesirable, especially for export markets. Fruit were

Analysis of non-TIR NBS-LRR resistance gene analogs in Musa acuminata Colla: Isolation, RFLP marker development, and physical mapping

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Souza Manoel T

2008-01-01

Full Text Available Abstract Background Many commercial banana varieties lack sources of resistance to pests and diseases, as a consequence of sterility and narrow genetic background. Fertile wild relatives, by contrast, possess greater variability and represent potential sources of disease resistance genes (R-genes. The largest known family of plant R-genes encode proteins with nucleotide-binding site (NBS and C-terminal leucine-rich repeat (LRR domains. Conserved motifs in such genes in diverse plant species offer a means for isolation of candidate genes in banana which may be involved in plant defence. Results A computational strategy was developed for unbiased conserved motif discovery in NBS and LRR domains in R-genes and homologues in monocotyledonous plant species. Degenerate PCR primers targeting conserved motifs were tested on the wild cultivar Musa acuminata subsp. burmannicoides, var. Calcutta 4, which is resistant to a number of fungal pathogens and nematodes. One hundred and seventy four resistance gene analogs (RGAs were amplified and assembled into 52 contiguous sequences. Motifs present were typical of the non-TIR NBS-LRR RGA subfamily. A phylogenetic analysis of deduced amino-acid sequences for 33 RGAs with contiguous open reading frames (ORFs, together with RGAs from Arabidopsis thaliana and Oryza sativa, grouped most Musa RGAs within monocotyledon-specific clades. RFLP-RGA markers were developed, with 12 displaying distinct polymorphisms in parentals and F1 progeny of a diploid M. acuminata mapping population. Eighty eight BAC clones were identified in M. acuminata Calcutta 4, M. acuminata Grande Naine, and M. balbisiana Pisang Klutuk Wulung BAC libraries when hybridized to two RGA probes. Multiple copy RGAs were common within BAC clones, potentially representing variation reservoirs for evolution of new R-gene specificities. Conclusion This is the first large scale analysis of NBS-LRR RGAs in M. acuminata Calcutta 4. Contig sequences were

The complete chloroplast genome of banana (Musa acuminata, Zingiberales): insight into plastid monocotyledon evolution.

Science.gov (United States)

Martin, Guillaume; Baurens, Franc-Christophe; Cardi, Céline; Aury, Jean-Marc; D'Hont, Angélique

2013-01-01

Banana (genus Musa) is a crop of major economic importance worldwide. It is a monocotyledonous member of the Zingiberales, a sister group of the widely studied Poales. Most cultivated bananas are natural Musa inter-(sub-)specific triploid hybrids. A Musa acuminata reference nuclear genome sequence was recently produced based on sequencing of genomic DNA enriched in nucleus. The Musa acuminata chloroplast genome was assembled with chloroplast reads extracted from whole-genome-shotgun sequence data. The Musa chloroplast genome is a circular molecule of 169,972 bp with a quadripartite structure containing two single copy regions, a Large Single Copy region (LSC, 88,338 bp) and a Small Single Copy region (SSC, 10,768 bp) separated by Inverted Repeat regions (IRs, 35,433 bp). Two forms of the chloroplast genome relative to the orientation of SSC versus LSC were found. The Musa chloroplast genome shows an extreme IR expansion at the IR/SSC boundary relative to the most common structures found in angiosperms. This expansion consists of the integration of three additional complete genes (rps15, ndhH and ycf1) and part of the ndhA gene. No such expansion has been observed in monocots so far. Simple Sequence Repeats were identified in the Musa chloroplast genome and a new set of Musa chloroplastic markers was designed. The complete sequence of M. acuminata ssp malaccensis chloroplast we reported here is the first one for the Zingiberales order. As such it provides new insight in the evolution of the chloroplast of monocotyledons. In particular, it reinforces that IR/SSC expansion has occurred independently several times within monocotyledons. The discovery of new polymorphic markers within Musa chloroplast opens new perspectives to better understand the origin of cultivated triploid bananas.

The complete chloroplast genome of banana (Musa acuminata, Zingiberales: insight into plastid monocotyledon evolution.

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Guillaume Martin

Full Text Available Banana (genus Musa is a crop of major economic importance worldwide. It is a monocotyledonous member of the Zingiberales, a sister group of the widely studied Poales. Most cultivated bananas are natural Musa inter-(sub-specific triploid hybrids. A Musa acuminata reference nuclear genome sequence was recently produced based on sequencing of genomic DNA enriched in nucleus.The Musa acuminata chloroplast genome was assembled with chloroplast reads extracted from whole-genome-shotgun sequence data. The Musa chloroplast genome is a circular molecule of 169,972 bp with a quadripartite structure containing two single copy regions, a Large Single Copy region (LSC, 88,338 bp and a Small Single Copy region (SSC, 10,768 bp separated by Inverted Repeat regions (IRs, 35,433 bp. Two forms of the chloroplast genome relative to the orientation of SSC versus LSC were found. The Musa chloroplast genome shows an extreme IR expansion at the IR/SSC boundary relative to the most common structures found in angiosperms. This expansion consists of the integration of three additional complete genes (rps15, ndhH and ycf1 and part of the ndhA gene. No such expansion has been observed in monocots so far. Simple Sequence Repeats were identified in the Musa chloroplast genome and a new set of Musa chloroplastic markers was designed.The complete sequence of M. acuminata ssp malaccensis chloroplast we reported here is the first one for the Zingiberales order. As such it provides new insight in the evolution of the chloroplast of monocotyledons. In particular, it reinforces that IR/SSC expansion has occurred independently several times within monocotyledons. The discovery of new polymorphic markers within Musa chloroplast opens new perspectives to better understand the origin of cultivated triploid bananas.

Pi-pi* orbital transitions and photo-degeneracy of C.acuminata sensitized solar cells

Science.gov (United States)

Abodunrin, T.; Boyo, A.; Usikalu, M.; Obafemi, L.; Oladapo, O.; Kotsedi, L.; Yenus, Z.; Maaza, M.

2017-04-01

Dye-sensitized solar cells (DSSCs) have acquired great prominence as favourable low-cost photovoltaics due to their ease of fabrication, all- year -availability, ease of obtaining raw materials and adjustable optical properties like transparency and colour. These advantages coupled with the ability to work under poor lighting makes them a suitable candidate for next generation of research. In this research, C.acuminata-sensitized photo anodes play an important role for achieving high performance since the porous metal oxide films provide a large specific surface area for dye loading and the possibility to extend the absorption threshold of past studies of sensitizers. The doctor blade method and high-temperature sintering were some of the methods used in the fabrication of the photo anode. A study of the performance of the C.acuminata-DSSCs with four different electrolyte sensitizers based on iodide redox mediator is determined. The result is DSSCs that exhibit a maximum power output of 39.37 W, fill factor of 0.7 and a power conversion efficiency of 0.6% under unfavourable sunlight intensity conditions and photo-degradation of about 37.5 % in absorbance after 425 suns.

Genetic variation of Lymnaea stagnalis tolerance to copper: A test of selection hypotheses and its relevance for ecological risk assessment

International Nuclear Information System (INIS)

Côte, Jessica; Bouétard, Anthony; Pronost, Yannick; Besnard, Anne-Laure; Coke, Maïra; Piquet, Fabien; Caquet, Thierry; Coutellec, Marie-Agnès

2015-01-01

The use of standardized monospecific testing to assess the ecological risk of chemicals implicitly relies on the strong assumption that intraspecific variation in sensitivity is negligible or irrelevant in this context. In this study, we investigated genetic variation in copper sensitivity of the freshwater snail Lymnaea stagnalis, using lineages stemming from eight natural populations or strains found to be genetically differentiated at neutral markers. Copper-induced mortality varied widely among populations, as did the estimated daily death rate and time to 50% mortality (LT50). Population genetic divergence in copper sensitivity was compared to neutral differentiation using the Q ST -F ST approach. No evidence for homogenizing selection could be detected. This result demonstrates that species-level extrapolations from single population studies are highly unreliable. The study provides a simple example of how evolutionary principles could be incorporated into ecotoxicity testing in order to refine ecological risk assessment. - Highlights: • Genetic variation in copper tolerance occurs between Lymnaea stagnalis populations. • We used the Q ST -F ST approach to test evolutionary patterns in copper tolerance. • No evidence for uniform selection was found. • Results suggest that extrapolations to the species level are not safe. • A method is proposed to refine ecological risk assessment using genetic parameters. - Genetic variation in copper tolerance occurs in Lymnaea stagnalis. A method is proposed for considering evolutionary parameters in ecological risk assessment

Impairing DNA methylation obstructs memory enhancement for at least 24?hours in Lymnaea

OpenAIRE

Rothwell, Cailin M.; Lukowiak, Ken D.

2017-01-01

ABSTRACT Stressor-induced memory enhancement has previously been shown to involve DNA methylation in the mollusc Lymnaea stagnalis. Specifically, injection of the DNA methylation inhibitor 5-AZA one hour before exposure to a memory-enhancing stressor obstructs memory augmentation. However, the duration of the influence of 5-AZA on this memory enhancement has not yet been examined. In this study, 2 memory-enhancing stressors (a thermal stress and exposure to the scent of a predator) were used ...

Role of tonic inhibition in associative reward conditioning in Lymnaea

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Vincenzo Marra

2010-09-01

Full Text Available Changes in the strength of excitatory synaptic connections are known to underlie associative memory formation in the molluscan nervous system but less is known about the role of synaptic inhibition. Tonic or maintained synaptic inhibition has an important function in controlling the Lymnaea feeding system and is known to suppress feeding in the absence of food or in satiated animals. Tonic inhibition to the feeding network is provided by the N3t interneuron that has inhibitory monosynaptic connection with the central pattern generator interneuron, the N1M. Here we asked whether a reduction in the level of tonic inhibition provided by the N3t cell could play a role in reward conditioning? Semi-intact preparations made from hungry snails were conditioned using a previously-developed one-trail chemical conditioning paradigm. We recorded electrical activity in a feeding motoneuron, the B3, at various time-points after conditioning. This allowed us to measure the frequency of spike activity in the N3t interneuron and monitor fictive feeding patterns that generate the rhythmic movements involved in food ingestion. We show that there is a reduction in N3t spiking at 1, 2, 3 and 4 hours after conditioning but not at 10 minutes and 30 minutes and the reduction in N3t firing inversely correlates with an increase in the conditioned fictive feeding response. Computer simulation of N3t-N1M interactions suggests that changes in N3t firing are sufficient to explain the increase in the fictive feeding activity produced by conditioning. A network model is presented that summarizes evidence suggesting that reward conditioning in Lymnaea is due to the combined effects of reduced tonic inhibition and enhanced excitatory synaptic connections between the CS pathway and feeding command neurons.

Phylogenetic placement of two previously described intranuclear bacteria from the ciliate Paramecium bursaria (Protozoa, Ciliophora): 'Holospora acuminata' and 'Holospora curviuscula'.

Science.gov (United States)

Rautian, Maria S; Wackerow-Kouzova, Natalia D

2013-05-01

'Holospora acuminata' infects micronuclei of Paramecium bursaria (Protozoa, Ciliophora), whereas 'Holospora curviuscula' infects the macronucleus in other clones of the same host species. Because these micro-organisms have not been cultivated, their description has been based only on some morphological properties and host and nuclear specificities. One16S rRNA gene sequence of 'H. curviuscula' is present in databases. The systematic position of the representative strain of 'H. curviuscula', strain MC-3, was determined in this study. Moreover, for the first time, two strains of 'H. acuminata', KBN10-1 and AC61-10, were investigated. Phylogenetic analysis indicated that all three strains belonged to the genus Holospora, family Holosporaceae, order Rickettsiales within the Alphaproteobacteria.

Rapid colonisation of Lymnaea stagnalis by larval trematodes in eutrophic ponds in central Europe

Czech Academy of Sciences Publication Activity Database

Soldánová, Miroslava; Kostadinova, Aneta

2011-01-01

Roč. 41, č. 9 (2011), 981-990 ISSN 0020-7519 R&D Projects: GA ČR GAP505/10/1562; GA ČR GD206/09/H026; GA MŠk LC522 Institutional research plan: CEZ:AV0Z60220518 Keywords : Lymnaea stagnalis * Freshwater pulmonate snail * Larval trematodes * Colonisation and extinction * Competition-colonisation trade-off * Eutrophic ponds * Central Europe Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 3.393, year: 2011

On the Ultrastructure and Function of Rhogocytes from the Pond Snail Lymnaea stagnalis.

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Maria Kokkinopoulou

Full Text Available Rhogocytes, also termed "pore cells", occur as solitary or clustered cells in the connective tissue of gastropod molluscs. Rhogocytes possess an enveloping lamina of extracellular matrix and enigmatic extracellular lacunae bridged by cytoplasmic bars that form 20 nm diaphragmatic slits likely to act as a molecular sieve. Recent papers highlight the embryogenesis and ultrastructure of these cells, and their role in heavy metal detoxification. Rhogocytes are the site of hemocyanin or hemoglobin biosynthesis in gastropods. Based on electron microscopy, we recently proposed a possible pathway of hemoglobin exocytosis through the slit apparatus, and provided molecular evidence of a common phylogenetic origin of molluscan rhogocytes, insect nephrocytes and vertebrate podocytes. However, the previously proposed secretion mode of the respiratory proteins into the hemolymph is still rather hypothetical, and the possible role of rhogocytes in detoxification requires additional data. Although our previous study on rhogocytes of the red-blooded (hemoglobin-containing freshwater snail Biomphalaria glabrata provided much new information, a disadvantage was that the hemoglobin molecules were not unequivocally defined in the electron microscope. This made it difficult to trace the exocytosis pathway of this protein. Therefore, we have now performed a similar study on the rhogocytes of the blue-blooded (hemocyanin-containing freshwater snail Lymnaea stagnalis. The intracellular hemocyanin could be identified in the electron microscope, either as individual molecules or as pseudo-crystalline arrays. Based on 3D-electron microscopy, and supplemented by in situ hybridization, immunocytochemistry and stress response experiments, we provide here additional details on the structure and hemocyanin biosynthesis of rhogocytes, and on their response in animals under cadmium and starvation stress. Moreover, we present an advanced model on the release of synthesized

Effects of Aqueous Extract of Three Cultivars of Banana (Musa acuminata) Fruit Peel on Kidney and Liver Function Indices in Wistar Rats.

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Edenta, Chidi; Okoduwa, Stanley I R; Okpe, Oche

2017-10-23

Background: Musa acuminata fruit peels are used in the northern part of Nigeria for the treatment of hypertension and other cardiovascular related diseases. The effects of aqueous extracts of ripped fruit peel of three cultivars of Musa acuminata ( Saro, Ominni and Oranta ) on the hepatic and renal parameters of normal rats were examined. Methods: Fruit peel aqueous extracts (FPAE) of the 3 cultivars of Bananas (100 mg/kg b.w.) were administered by oral intubation (that is through esophageal cannula) to normal rats (140-180 g) for a period of 28 days. Blood samples were collected for determination of plasma aspartate amino transferase (AST), alanine amino transferase (ALT), alkaline phosphatase ALK-P), total protein, albumin, creatinine as well as urea. Results: From the results obtained, there were no significant ( p < 0.05) changes in the ALK-P, AST, ALT, total protein and albumin among the experimental rats administered FPAE of the 3 cultivars of Musa acuminata when compared with the normal control group. There was a significant ( p < 0.05) increase in the level of serum creatinine (in mg/dL) (1.53 ± 0.23) when compared to the normal control (0.72 ± 0.15), Ominni (0.92 ± 0.39) and Oranta (0.74 ± 0.22). Similarly, there was a significant ( p < 0.05) increase in the level of serum urea (in mg/dL) of Saro (41.56 ± 4.68) when compared to the normal control (26.05 ± 0.73), Ommini (28.44 ± 2.43) and Oranta (26.10 ± 2.94). Conclusion: The findings reveal the Saro cultivar of Musa acuminata to be nephrotoxic and not a good potential drug candidate among the cultivars studied hence should be discouraged in the treatment of hypertension and other cardiovascular related diseases.

Effects of Aqueous Extract of Three Cultivars of Banana (Musa acuminata) Fruit Peel on Kidney and Liver Function Indices in Wistar Rats

Science.gov (United States)

Edenta, Chidi; Okpe, Oche

2017-01-01

Background: Musa acuminata fruit peels are used in the northern part of Nigeria for the treatment of hypertension and other cardiovascular related diseases. The effects of aqueous extracts of ripped fruit peel of three cultivars of Musa acuminata (Saro, Ominni and Oranta) on the hepatic and renal parameters of normal rats were examined. Methods: Fruit peel aqueous extracts (FPAE) of the 3 cultivars of Bananas (100 mg/kg b.w.) were administered by oral intubation (that is through esophageal cannula) to normal rats (140–180 g) for a period of 28 days. Blood samples were collected for determination of plasma aspartate amino transferase (AST), alanine amino transferase (ALT), alkaline phosphatase ALK-P), total protein, albumin, creatinine as well as urea. Results: From the results obtained, there were no significant (p < 0.05) changes in the ALK-P, AST, ALT, total protein and albumin among the experimental rats administered FPAE of the 3 cultivars of Musa acuminata when compared with the normal control group. There was a significant (p < 0.05) increase in the level of serum creatinine (in mg/dL) (1.53 ± 0.23) when compared to the normal control (0.72 ± 0.15), Ominni (0.92 ± 0.39) and Oranta (0.74 ± 0.22). Similarly, there was a significant (p < 0.05) increase in the level of serum urea (in mg/dL) of Saro (41.56 ± 4.68) when compared to the normal control (26.05 ± 0.73), Ommini (28.44 ± 2.43) and Oranta (26.10 ± 2.94). Conclusion: The findings reveal the Saro cultivar of Musa acuminata to be nephrotoxic and not a good potential drug candidate among the cultivars studied hence should be discouraged in the treatment of hypertension and other cardiovascular related diseases. PMID:29065553

Effects of Aqueous Extract of Three Cultivars of Banana (Musa acuminata Fruit Peel on Kidney and Liver Function Indices in Wistar Rats

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Chidi Edenta

2017-10-01

Full Text Available Background: Musa acuminata fruit peels are used in the northern part of Nigeria for the treatment of hypertension and other cardiovascular related diseases. The effects of aqueous extracts of ripped fruit peel of three cultivars of Musa acuminata (Saro, Ominni and Oranta on the hepatic and renal parameters of normal rats were examined. Methods: Fruit peel aqueous extracts (FPAE of the 3 cultivars of Bananas (100 mg/kg b.w. were administered by oral intubation (that is through esophageal cannula to normal rats (140–180 g for a period of 28 days. Blood samples were collected for determination of plasma aspartate amino transferase (AST, alanine amino transferase (ALT, alkaline phosphatase ALK-P, total protein, albumin, creatinine as well as urea. Results: From the results obtained, there were no significant (p < 0.05 changes in the ALK-P, AST, ALT, total protein and albumin among the experimental rats administered FPAE of the 3 cultivars of Musa acuminata when compared with the normal control group. There was a significant (p < 0.05 increase in the level of serum creatinine (in mg/dL (1.53 ± 0.23 when compared to the normal control (0.72 ± 0.15, Ominni (0.92 ± 0.39 and Oranta (0.74 ± 0.22. Similarly, there was a significant (p < 0.05 increase in the level of serum urea (in mg/dL of Saro (41.56 ± 4.68 when compared to the normal control (26.05 ± 0.73, Ommini (28.44 ± 2.43 and Oranta (26.10 ± 2.94. Conclusion: The findings reveal the Saro cultivar of Musa acuminata to be nephrotoxic and not a good potential drug candidate among the cultivars studied hence should be discouraged in the treatment of hypertension and other cardiovascular related diseases.

Structural and Function Prediction of Musa acuminata subsp. Malaccensis Protein

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Anum Munir

2016-03-01

Full Text Available Hypothetical proteins (HPs are the proteins whose presence has been anticipated, yet in vivo function has not been built up. Illustrating the structural and functional privileged insights of these HPs might likewise prompt a superior comprehension of the protein-protein associations or networks in diverse types of life. Bananas (Musa acuminata spp., including sweet and cooking types, are giant perennial monocotyledonous herbs of the order Zingiberales, a sister grouped to the all-around considered Poales, which incorporate oats. Bananas are crucial for nourishment security in numerous tropical and subtropical nations and the most prominent organic product in industrialized nations. In the present study, the hypothetical protein of M. acuminata (Banana was chosen for analysis and modeling by distinctive bioinformatics apparatuses and databases. As indicated by primary and secondary structure analysis, XP_009393594.1 is a stable hydrophobic protein containing a noteworthy extent of α-helices; Homology modeling was done utilizing SWISS-MODEL server where the templates identity with XP_009393594.1 protein was less which demonstrated novelty of our protein. Ab initio strategy was conducted to produce its 3D structure. A few evaluations of quality assessment and validation parameters determined the generated protein model as stable with genuinely great quality. Functional analysis was completed by ProtFun 2.2, and KEGG (KAAS, recommended that the hypothetical protein is a transcription factor with cytoplasmic domain as zinc finger. The protein was observed to be vital for translation process, involved in metabolism, signaling and cellular processes, genetic information processing and Zinc ion binding. It is suggested that further test approval would help to anticipate the structures and functions of other uncharacterized proteins of different plants and living being.

Genome-wide BAC-end sequencing of Musa acuminata DH Pahang reveals further insights into the genome organization of banana

NARCIS (Netherlands)

Arnago, R.E.; Togawa, R.C.; Carpentier, S.C.; Lintel Hekkert, te B.; Kema, G.H.J.; Souza, M.T.

2011-01-01

Banana and plantain (Musa spp.) are grown in more than 120 countries in tropical and subtropical regions and constitute an important staple food for millions of people. A Musa acuminata ssp. malaccencis DH Pahang bacterial artificial chromosome (BAC) library (MAMB) was submitted for BAC-end

Improvement of the banana "Musa acuminata" reference sequence using NGS data and semi-automated bioinformatics methods.

Science.gov (United States)

Martin, Guillaume; Baurens, Franc-Christophe; Droc, Gaëtan; Rouard, Mathieu; Cenci, Alberto; Kilian, Andrzej; Hastie, Alex; Doležel, Jaroslav; Aury, Jean-Marc; Alberti, Adriana; Carreel, Françoise; D'Hont, Angélique

2016-03-16

Recent advances in genomics indicate functional significance of a majority of genome sequences and their long range interactions. As a detailed examination of genome organization and function requires very high quality genome sequence, the objective of this study was to improve reference genome assembly of banana (Musa acuminata). We have developed a modular bioinformatics pipeline to improve genome sequence assemblies, which can handle various types of data. The pipeline comprises several semi-automated tools. However, unlike classical automated tools that are based on global parameters, the semi-automated tools proposed an expert mode for a user who can decide on suggested improvements through local compromises. The pipeline was used to improve the draft genome sequence of Musa acuminata. Genotyping by sequencing (GBS) of a segregating population and paired-end sequencing were used to detect and correct scaffold misassemblies. Long insert size paired-end reads identified scaffold junctions and fusions missed by automated assembly methods. GBS markers were used to anchor scaffolds to pseudo-molecules with a new bioinformatics approach that avoids the tedious step of marker ordering during genetic map construction. Furthermore, a genome map was constructed and used to assemble scaffolds into super scaffolds. Finally, a consensus gene annotation was projected on the new assembly from two pre-existing annotations. This approach reduced the total Musa scaffold number from 7513 to 1532 (i.e. by 80%), with an N50 that increased from 1.3 Mb (65 scaffolds) to 3.0 Mb (26 scaffolds). 89.5% of the assembly was anchored to the 11 Musa chromosomes compared to the previous 70%. Unknown sites (N) were reduced from 17.3 to 10.0%. The release of the Musa acuminata reference genome version 2 provides a platform for detailed analysis of banana genome variation, function and evolution. Bioinformatics tools developed in this work can be used to improve genome sequence assemblies in

Don't camp beside the river: structure and dynamics of Andean alder (Alnus acuminata forests affected by river floods, northwestern Argentina No acampe junto al río: estructura y dinámica de bosques de aliso (Alnus acuminata del noroeste argentino afectados por crecientes de río

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TOMÁS A EASDALE

2005-12-01

Full Text Available Alnus acuminata (Betulaceae is a pioneer tree that dominates mountain riparian forests throughout the eastern Andes. Early studies associated these forests with particular microclimatic conditions along river beds, but they were later linked to the periodical disturbance regime of mountain rivers. To understand the dynamics of these forests, we analysed tree age and spatial arrangement in two plots along Potrero river and another plot along La Horqueta river, Tucumán Province, north west Argentina. Through intensive tree coring and age reconstruction we identified similar-aged tree cohorts with maximum age ranges of eight years. Tree mapping and Moran's I spatial autocorrelation analysis showed that tree cohorts were spatially clumped, and provided further evidence that coetaneous patches of A. acuminata arise from massive regeneration following catastrophic flooding events. We tested the association between cohort initiation dates and regional maximum river discharge records by means of a randomization procedure and found weak evidence that establishment occurs after devastating floods, which eliminate previous vegetation and create bare sites suitable for A. acuminata regeneration. Dates of tree floodscars sampled along Potrero river precede by one year the most recent cohort initiation date and provide further support of this association. Although previous studies found a positive correlation between El Niño events and mean annual precipitation in northwestern Argentina, we did not detect an association between El Niño and annual maximum stream flow for rivers in Tucumán Province. Therefore, factors driving devastating floods and A. acuminata stand initiation require further studyEl aliso (Alnus acuminata, Betulaceae es un árbol pionero que domina bosques riparios de montaña en los Andes orientales. Estudios iniciales atribuyeron la presencia de estos bosques a las típicas condiciones microclimáticas de cauces de ríos, pero luego

Two Strains of Lymnaea stagnalis and the Progeny from Their Mating Display Differential Memory-Forming Ability on Associative Learning Tasks.

Science.gov (United States)

Sunada, Hiroshi; Totani, Yuki; Nakamura, Ryota; Sakakibara, Manabu; Lukowiak, Ken; Ito, Etsuro

2017-01-01

The pond snail Lymnaea stagnalis learns and forms long-term memory (LTM) following both operant conditioning of aerial respiratory behavior and classical conditioning of taste aversive behavior. In the present study, we examined whether there are interstrain differences in the ability to form LTM following these two types of conditioning. A strain of Lymnaea (TC1) collected in Alberta, Canada exhibits superior memory-forming ability following aerial respiratory operant conditioning compared to a laboratory-reared strain of Lymnaea from Netherlands known as the Dutch strain. We asked whether the offspring of the Canadian TC1 and Dutch snails (i.e., filial 1 (F 1 ) cross snails) would have the superior memory ability and found, rather, that their memory ability was average like the Dutch snails. That is, the Canadian TC1 snails have superior ability for LTM formation following aerial respiratory operant conditioning, but the Dutch and the generated F 1 cross have average ability for memory forming. We next examined the Canadian TC1, Dutch and F 1 cross snails for their ability to learn and form memory following conditioned taste aversion (CTA). All three populations showed similar associative CTA responses. However, both LTM formation and the ratio of good-to-poor performers in the memory retention test were much better in the Dutch snails than the Canadian TC1 and F 1 cross snails. The memory abilities of the Canadian TC1 and F 1 cross snails were average. Our present findings, therefore, suggest that snails of different strains have different memory abilities, and the F 1 cross snails do not inherit the memory ability from the smart strain. To our knowledge, there have been a limited number of studies examining differences in memory ability among invertebrate strains, with the exception of studies using mutant flies.

Two Strains of Lymnaea stagnalis and the Progeny from Their Mating Display Differential Memory-Forming Ability on Associative Learning Tasks

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Hiroshi Sunada

2017-09-01

Full Text Available The pond snail Lymnaea stagnalis learns and forms long-term memory (LTM following both operant conditioning of aerial respiratory behavior and classical conditioning of taste aversive behavior. In the present study, we examined whether there are interstrain differences in the ability to form LTM following these two types of conditioning. A strain of Lymnaea (TC1 collected in Alberta, Canada exhibits superior memory-forming ability following aerial respiratory operant conditioning compared to a laboratory-reared strain of Lymnaea from Netherlands known as the Dutch strain. We asked whether the offspring of the Canadian TC1 and Dutch snails (i.e., filial 1 (F1 cross snails would have the superior memory ability and found, rather, that their memory ability was average like the Dutch snails. That is, the Canadian TC1 snails have superior ability for LTM formation following aerial respiratory operant conditioning, but the Dutch and the generated F1 cross have average ability for memory forming. We next examined the Canadian TC1, Dutch and F1 cross snails for their ability to learn and form memory following conditioned taste aversion (CTA. All three populations showed similar associative CTA responses. However, both LTM formation and the ratio of good-to-poor performers in the memory retention test were much better in the Dutch snails than the Canadian TC1 and F1 cross snails. The memory abilities of the Canadian TC1 and F1 cross snails were average. Our present findings, therefore, suggest that snails of different strains have different memory abilities, and the F1 cross snails do not inherit the memory ability from the smart strain. To our knowledge, there have been a limited number of studies examining differences in memory ability among invertebrate strains, with the exception of studies using mutant flies.

Effect of microgravity simulation using 3D clinostat on cavendish banana (Musa acuminata AAA Group) ripening process

Science.gov (United States)

Dwivany, Fenny Martha; Esyanti, Rizkita R.; Prapaisie, Adeline; Puspa Kirana, Listya; Latief, Chunaeni; Ginaldi, Ari

2016-11-01

The objective of the research was to determine the effect of microgravity simulation by 3D clinostat on Cavendish banana (Musa acuminata AAA group) ripening process. In this study, physical, physiological changes as well as genes expression were analysed. The result showed that in microgravity simulation condition ripening process in banana was delayed and the MaACOl, MaACSl and MaACS5 gene expression were affected.

Detection of Lymnaea columella infection by Fasciola hepatica through Multiplex-PCR

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Kelly Grace Magalhães

2004-06-01

Full Text Available From complete mitochondrial DNA sequence of Fasciola hepatica available in Genbank, specific primers were designed for a conserved and repetitive region of this trematode. A pair of primers was used for diagnosis of infected Lymnaea columella by F. hepatica during the pre-patent period simultaneously with another pair of primers which amplified the internal transcribed spacer (ITS region of rDNA from L. columella in a single Multiplex-PCR. The amplification generated a ladder band profile specific for F. hepatica. This profile was observed in positive molluscs at different times of infection, including adult worms from the trematode. The Multiplex-PCR technique showed to be a fast and safe tool for fascioliasis diagnosis, enabling the detection of F. hepatica miracidia in L. columella during the pre-patent period and identification of transmission areas.

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

Science.gov (United States)

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

2009-01-01

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

Memory trace in feeding neural circuitry underlying conditioned taste aversion in Lymnaea.

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Etsuro Ito

Full Text Available BACKGROUND: The pond snail Lymnaea stagnalis can maintain a conditioned taste aversion (CTA as a long-term memory. Previous studies have shown that the inhibitory postsynaptic potential (IPSP evoked in the neuron 1 medial (N1M cell by activation of the cerebral giant cell (CGC in taste aversion-trained snails was larger and lasted longer than that in control snails. The N1M cell is one of the interneurons in the feeding central pattern generator (CPG, and the CGC is a key regulatory neuron for the feeding CPG. METHODOLOGY/PRINCIPLE FINDINGS: Previous studies have suggested that the neural circuit between the CGC and the N1M cell consists of two synaptic connections: (1 the excitatory connection from the CGC to the neuron 3 tonic (N3t cell and (2 the inhibitory connection from the N3t cell to the N1M cell. However, because the N3t cell is too small to access consistently by electrophysiological methods, in the present study the synaptic inputs from the CGC to the N3t cell and those from the N3t cell to the N1M cell were monitored as the monosynaptic excitatory postsynaptic potential (EPSP recorded in the large B1 and B3 motor neurons, respectively. The evoked monosynaptic EPSPs of the B1 motor neurons in the brains isolated from the taste aversion-trained snails were identical to those in the control snails, whereas the spontaneous monosynaptic EPSPs of the B3 motor neurons were significantly enlarged. CONCLUSION/SIGNIFICANCE: These results suggest that, after taste aversion training, the monosynaptic inputs from the N3t cell to the following neurons including the N1M cell are specifically facilitated. That is, one of the memory traces for taste aversion remains as an increase in neurotransmitter released from the N3t cell. We thus conclude that the N3t cell suppresses the N1M cell in the feeding CPG, in response to the conditioned stimulus in Lymnaea CTA.

Memory trace in feeding neural circuitry underlying conditioned taste aversion in Lymnaea.

Science.gov (United States)

Ito, Etsuro; Otsuka, Emi; Hama, Noriyuki; Aonuma, Hitoshi; Okada, Ryuichi; Hatakeyama, Dai; Fujito, Yutaka; Kobayashi, Suguru

2012-01-01

The pond snail Lymnaea stagnalis can maintain a conditioned taste aversion (CTA) as a long-term memory. Previous studies have shown that the inhibitory postsynaptic potential (IPSP) evoked in the neuron 1 medial (N1M) cell by activation of the cerebral giant cell (CGC) in taste aversion-trained snails was larger and lasted longer than that in control snails. The N1M cell is one of the interneurons in the feeding central pattern generator (CPG), and the CGC is a key regulatory neuron for the feeding CPG. Previous studies have suggested that the neural circuit between the CGC and the N1M cell consists of two synaptic connections: (1) the excitatory connection from the CGC to the neuron 3 tonic (N3t) cell and (2) the inhibitory connection from the N3t cell to the N1M cell. However, because the N3t cell is too small to access consistently by electrophysiological methods, in the present study the synaptic inputs from the CGC to the N3t cell and those from the N3t cell to the N1M cell were monitored as the monosynaptic excitatory postsynaptic potential (EPSP) recorded in the large B1 and B3 motor neurons, respectively. The evoked monosynaptic EPSPs of the B1 motor neurons in the brains isolated from the taste aversion-trained snails were identical to those in the control snails, whereas the spontaneous monosynaptic EPSPs of the B3 motor neurons were significantly enlarged. These results suggest that, after taste aversion training, the monosynaptic inputs from the N3t cell to the following neurons including the N1M cell are specifically facilitated. That is, one of the memory traces for taste aversion remains as an increase in neurotransmitter released from the N3t cell. We thus conclude that the N3t cell suppresses the N1M cell in the feeding CPG, in response to the conditioned stimulus in Lymnaea CTA.

A μ-biomimetic uncooled infrared sensor based on the infrared receptors of Melanophila acuminata

International Nuclear Information System (INIS)

Siebke, Georg

2015-11-01

The pyrophilous beetle Melanophila acuminata possesses an organ sensitive to IR radiation. It employs a photomechanic detection principle: A liquid filled pressure chamber is heated by absorbing the radiation. The liquid expands and leads to the deflection of a mechanosensitive dendrite. In addition, a sophisticated compensation mechanism prevents the build-up of large pressures. In this work, a biomimetic IR sensor based on the IR receptors of Melanophila acuminata is developed by means of microsystems technology. The sensor consists of two liquid-filled chambers that are connected by a micro-fluidic system. Absorption of IR radiation by one of the chambers leads to the heating and expansion of a liquid. The increasing pressure deflects a membrane which is part of a plate capacitor with a diameter of 500 μm and an electrode distance of 500 nm. The micro-fluidic system and the second chamber represent a fluidic low-pass filter, preventing slow, but large pressure changes. A theoretical model is developed which is able to predict the modulation frequency dependent response. It allows to calculate the filter properties of the compensation mechanism which is verified by an experimental test. A simplified sensor without the compensation mechanism is manufactured to analyse the influence of several parameters on the sensor's sensitivity. Finally, a solution for the fabrication of the μ-capacitor is presented. The large aspect ratio between electrode diameter and distance prevents to use a standard sacrificial layer process. The obtained capacitors pave the way to fabricate the complete full-featured sensor.

A μ-biomimetic uncooled infrared sensor based on the infrared receptors of Melanophila acuminata

Energy Technology Data Exchange (ETDEWEB)

Siebke, Georg

2015-11-15

The pyrophilous beetle Melanophila acuminata possesses an organ sensitive to IR radiation. It employs a photomechanic detection principle: A liquid filled pressure chamber is heated by absorbing the radiation. The liquid expands and leads to the deflection of a mechanosensitive dendrite. In addition, a sophisticated compensation mechanism prevents the build-up of large pressures. In this work, a biomimetic IR sensor based on the IR receptors of Melanophila acuminata is developed by means of microsystems technology. The sensor consists of two liquid-filled chambers that are connected by a micro-fluidic system. Absorption of IR radiation by one of the chambers leads to the heating and expansion of a liquid. The increasing pressure deflects a membrane which is part of a plate capacitor with a diameter of 500 μm and an electrode distance of 500 nm. The micro-fluidic system and the second chamber represent a fluidic low-pass filter, preventing slow, but large pressure changes. A theoretical model is developed which is able to predict the modulation frequency dependent response. It allows to calculate the filter properties of the compensation mechanism which is verified by an experimental test. A simplified sensor without the compensation mechanism is manufactured to analyse the influence of several parameters on the sensor's sensitivity. Finally, a solution for the fabrication of the μ-capacitor is presented. The large aspect ratio between electrode diameter and distance prevents to use a standard sacrificial layer process. The obtained capacitors pave the way to fabricate the complete full-featured sensor.

Diurnal productivity and apparent 14C-calcification in the staghorn coral, Acropora acuminata

International Nuclear Information System (INIS)

Barnes, D.J.; Crossland, C.J.

1978-01-01

The rate of 14 C-fixation by Acropora acuminata tissues showed a marked increase after dawn. However, maximum 14 C-fixation was not achieved until early afternoon. The apparent 14 C-incorporation rate into the skeleton of whole branches reached a peak around noon. However, the major period of 14 C-deposition occurred from noon to mid-afternoon. The broad peak of 14 C-incorporation into skeleton of whole branches reflects two rate maxima; a late-morning maximum of zooxanthellae-free terminal calices, probably related to translocation of fixed carbon from basal tissues; and an early afternoon maximum for the zooxanthellae-containing basal areas of branches. (author)

Composición química y actividad antibacteriana del aceite esencial de Peperomia acuminata de los Andes venezolanos

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Flor D. Mora-Vivas

2016-12-01

Full Text Available El género Peperomia (Piperaceae, es bien conocido por sus especies ornamentales y usos etnomedicinales. En el presente trabajo se describe la caracterización química y la actividad antibacteriana del aceite esencial de Peperomia acuminata Ruiz & Pav. proveniente del Estado Mérida Venezuela. El aceite esencial se obtuvo por hidrodestilación de las hojas y la separación de los componentes se realizó por Cromatografía de gases-Espectrometría de Masas (CG/EM. Se logró la elucidación de ocho compuestos (96,7%, siendo el 2E-dodecenal el componente mayoritario (65% seguido de dodecanal (14,8% y tetradecanal (9,2%. Esta investigación muestra el potencial del aceite esencial de P. acuminata frente a bacterias Gram positivas (Staphylococcus aureus ATCC 25923 y Enterococcus faecalis 29212, con un valor de Concentración inhibitoria mínima de 1μL/mL. Este es el primer reporte sobre la composición química del aceite esencial de esta especie, por lo tanto una contribución importante al estudio del género Peperomia.

Cerebral Giant Cells are Necessary for the Formation and Recall of Memory of Conditioned Taste Aversion in Lymnaea.

Science.gov (United States)

Sunada, Hiroshi; Lukowiak, Ken; Ito, Etsuro

2017-02-01

The pond snail Lymnaea stagnalis can acquire conditioned taste aversion (CTA) as a long-term memory. CTA is caused by the temporal pairing of a stimulus, such as sucrose (the conditioned stimulus; CS), with another stimulus, such as electric shock (the unconditioned stimulus; US). Previous studies have demonstrated changes in both cellular and molecular properties in a pair of neurons known as the cerebral giant cells (CGCs), suggesting that these neurons play a key role in CTA. Here we examined the necessity of the pair of CGC somata for the learning, memory formation and memory recall of CTA by using the soma ablation technique. There was no difference in the feeding response elicited by the CS before and after ablation of the CGC somata. Ablation of the CGC somata before taste-aversion training resulted in the learning acquisition, but the memory formation was not observed 24 h later. We next asked whether memory was present when the CGC somata were ablated 24 h after taste-aversion training. The memory was present before performing the somata ablation. However, when we tested snails five days after somata ablation, the memory recall was not present. Together the data show that: 1) the somata of the CGCs are not necessary for learning acquisition; 2) the somata are necessary for memory formation; and 3) the somata are necessary for memory recall. That is, these results demonstrate that the CGCs function in the long-term memory of CTA in Lymnaea.

Optimizing the design of a reproduction toxicity test with the pond snail Lymnaea stagnalis

DEFF Research Database (Denmark)

Charles, Sandrine; Ducrot, Virginie; Azam, Didier

2016-01-01

This paper presents the results from two ring-tests addressing the feasibility, robustness and reproducibility of a reproduction toxicity test with the freshwater gastropod Lymnaea stagnalis (RENILYS strain). Sixteen laboratories (from inexperienced to expert laboratories in mollusc testing) from...... nine countries participated in these ring-tests. Survival and reproduction were evaluated in L. stagnalis exposed to cadmium, tributyltin, prochloraz and trenbolone according to an OECD draft Test Guideline. In total, 49 datasets were analysed to assess the practicability of the proposed experimental...... protocol, and to estimate the between-laboratory reproducibility of toxicity endpoint values. The statistical analysis of count data (number of clutches or eggs per individual-day) leading to ECx estimation was specifically developed and automated through a free web-interface. Based on a complementary...

Coordination of locomotor and cardiorespiratory networks of Lymnaea stagnalis by a pair of identified interneurones.

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Syed, N I; Winlow, W

1991-07-01

1. The morphology and electrophysiology of a newly identified bilateral pair of interneurones in the central nervous system of the pulmonate pond snail Lymnaea stagnalis is described. 2. These interneurones, identified as left and right pedal dorsal 11 (L/RPeD11), are electrically coupled to each other as well as to a large number of foot and body wall motoneurones, forming a fast-acting neural network which coordinates the activities of foot and body wall muscles. 3. The left and right sides of the body wall of Lymnaea are innervated by left and right cerebral A cluster neurones. Although these motoneurones have only ipsilateral projections, they are indirectly electrically coupled to their contralateral homologues via their connections with L/RPeD11. Similarly, the activities of left and right pedal G cluster neurones, which are known to be involved in locomotion, are also coordinated by L/RPeD11. 4. Selective ablation of both neurones PeD11 results in the loss of coordination between the bilateral cerebral A clusters. 5. Interneurones L/RPeD11 are multifunctional. In addition to coordinating motoneuronal activity, they make chemical excitatory connections with heart motoneurones. They also synapse upon respiratory motoneurones, hyperpolarizing those involved in pneumostome opening (expiration) and depolarizing those involved in pneumostome closure (inspiration). 6. An identified respiratory interneurone involved in pneumostome closure (visceral dorsal 4) inhibits L/RPeD11 together with all their electrically coupled follower cells. 7. Both L/RPeD11 have strong excitatory effects on another pair of electrically coupled neurones, visceral dorsal 1 and right parietal dorsal 2, which have previously been shown to be sensitive to changes in the partial pressure of environmental oxygen (PO2). 8. Although L/RPeD11 participate in whole-body withdrawal responses, electrical stimulation applied directly to these neurones was not sufficient to induce this behaviour.

Contribución al conocimiento de la biología y taxonomía de un hongo del género Phytium aislado del "aliso", Alnus acuminata HBK

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Marina Correa de Restrepo

1990-01-01

Full Text Available Some biological aspects of an isolated fungus of Alnus acuminata roots were studied. It bas been found Tbat between OOC and 4°C tbe fungi grows fast. This condition can result in a important factor in the ecophysiology of 'Aliso' populations, that grows in secondary forests at sub-paramo, After a review of the taxonomic literature, we placed it in the Phytium genus, but not in a particular described species. We assume that it is a new species. We modificated the microculture technique that was simpler and safer and them we made direct observations about tbe fungus growtb and development. As for now it is nominated as Phytiun near Mammillatum Meurs. Palabras Claves: Phytium, bongos, A/nus acuminata HBK., "Aliso".

Consolidation of long-term memory by insulin in Lymnaea is not brought about by changing the number of insulin receptors

OpenAIRE

Hatakeyama, Dai; Okuta, Akiko; Otsuka, Emi; Lukowiak, Ken; Ito, Etsuro

2013-01-01

The pond snail Lymnaea stagnalis learns taste aversion and consolidates it into long-term memory (LTM). This is referred to as conditioned taste aversion (CTA). The superfusion of molluscan insulin-related peptides (MIPs) over the isolated snail brain causes a long-term enhancement of synaptic input between the cerebral giant cell and the B1 buccal motor neuron. This enhancement is hypothesized to underlie CTA. The synaptic enhancement caused by the superfusion of MIPs can be blocked by the a...

Prevalence of Cercariae Infection in Lymnaea auricularia (Linnaeus, 1758 in NorthWest of Iran

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Abbas Imani-Baran

2011-06-01

Full Text Available The pond snail Lymnaea auricularia serves as an intermediate host for many digenian species. In West Azerbaijan province, northwestern Iran, the cercariae infection investigation was undertaken in L. auricularia from May to November 2010. Of 6759 collected Lymnaeid snails, 370(5.5% L. auricularia snails were identified. Cercariae infection was found in a number of 276 (74.56 % snails. The results showed that removed cercariae from L. auricularia belonged to Echinostomcercariae (96.38 % and Furcocercariae (3.62 % which were found in two out of 28 sites during the course of study. In summer and fall, the highest prevalence of cercariae infection was recorded for both identified cercariae. It is concluded that L. auricularia could be an important intermediate host of large group digenian trematodes in the region, which is necessary to take consideration in the control program of trematode infection.

Verspreiding en habitats van Lymnaea natalensis, tussengasheerslak van die lewerbot Fasciola gigantica, in Suid-Afrika

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K. N. de Kock

2001-09-01

Full Text Available Hierdie artikel fokus op die geografiese verspreiding en die habitats van Lymnaea natalensis, die slaktussengasheer van die lewerbot, Fasciola gigantica, soos gereflekteer deur die vindplekke van sy 4 552 monsters wat tans in die Nasionale Varswaterslakversameling (NVV van Suid-Afrika op rekord is. Alhoewel hierdie spesie in’n verskeidenheid van waterliggame aangetref is, was die meerderheid van die monsters (±70% afkomstig vanuit riviere, spruite en damme en is die water in 70.8% van die gevalle as standhoudend en in 71.8% van die gevalle as stadigvloeiend, of staande beskryf.  Die resultate van lewenstabeleksperimente deur verskeie outeurs het daarop gedui dat temperatuur ’n minder belangrike bepalende faktor in sy geografiese verspreiding blyk te wees, maar dat die beskikbaarheid van standhoudende water deurslaggewend vir sy voorkoms in ’n gegewe habitat mag wees. Hierdie resultate strook met die bevinding dat slegs 7.5% van die monsters van hierdie spesie in die NVV in habitats wat as seisoenaal beskryf is, versamel is. Verder bied dit’n logiese verklaring vir die sporadiese voorkoms, of totale afwesigheid van hierdie spesie in die droër streke van Suid-Afrika.  Opgaardamme en besproeiingsnetwerke dra grootliks by tot die skepping van permanente habitats wat geskik sou wees vir L. natalensis.  As tussengasheer vir een van die lewerbotspesies wat reeds ’n ekonomiese faktor in Suid-Afrika is, is dit ’n aspek waarmee beslis rekening gehou behoort te word in die beplanning en konstruksie van nuwe besproeiingsprojekte.AbstractDistribution and habitats of Lymnaea natalensis, snail intermediate host of the liver fluke Fasciola gigantica, in South Africa This paper focuses on the geographical distribution and the habitats of Lymnaea natalensis, the snail intermediate host of the liver fluke, Fasciola gigantica, as reflected by the collection sites of its 4 552 samples currently on record in the National Freshwater Snail Collection

Chemical speciation and bioavailability of transuranics for a freshwater snail (Lymnaea stagnalis L.)

International Nuclear Information System (INIS)

Thiels, G.M.; Murray, C.N.; Rade, J.

1981-01-01

It is now becoming clear that the determination of the physico-chemical forms of transuranic elements is an important step in assessing their behaviour at very low environmental levels. Data from both simulated environmental systems as well as in-situ investigations have shown the necessity of understanding the source term of contamination, which probably plays a major role in the long-term distribution of these elements. In the present paper an experimental procedure is outlined, which allows a more extensive investigation into some aspects of the biogeochemical behaviour of two transuranics: 237 Pu and 241 Am. Two chemical methods were applied to a study of the freshwater snail Lymnaea stagnalis L.. Data were obtained on the uptake and retention patterns of different oxidation states of 237 Pu and 241 Am at the organ and cellular levels of the pond snail. An attempt was made to relate the environmental chemistry of both radionuclides to the fixation in L. stagnalis. (author)

'Different strokes for different folks': geographically isolated strains of Lymnaea stagnalis only respond to sympatric predators and have different memory forming capabilities.

Science.gov (United States)

Orr, Michael V; Hittel, Karla; Lukowiak, Ken

2009-07-01

Gaining insight into how natural trait variation is manifest in populations shaped by differential environmental factors is crucial to understanding the evolution, ecology and sensory biology of natural populations. We have demonstrated that lab-reared Lymnaea detect and respond to the scent of a crayfish predator with specific, appropriate anti-predator behavioral responses, including enhanced long-term memory (LTM) formation, and that such predator detection significantly alters the electrophysiological activity of RPeD1, a neuron that is a necessary site for LTM formation. Here we ask: (1) do distinct populations of wild Lymnaea stagnalis respond only to sympatric predators and if so, can these traits be quantified at both the behavioral and neurophysiological levels, and (2) does the presence of a non-sympatric predator elicit anti-predator behaviors including augmentation of LTM? We tested three different populations of wild (i.e. not lab-reared) snails freshly collected from their natural habitat: (1) polders near Utrecht in The Netherlands, (2) six seasonally isolated ponds in the Belly River drainage in southern Alberta, Canada and (3) a 20-year-old human-made dugout pond in southern Alberta. We found strain-specific variations in the ability to form LTM and that only a sympatric predator evoked anti-predatory behaviors, including enhanced LTM formation and changes in RPeD1 activity.

Genomic analysis of NAC transcription factors in banana (Musa acuminata) and definition of NAC orthologous groups for monocots and dicots.

Science.gov (United States)

Cenci, Albero; Guignon, Valentin; Roux, Nicolas; Rouard, Mathieu

2014-05-01

Identifying the molecular mechanisms underlying tolerance to abiotic stresses is important in crop breeding. A comprehensive understanding of the gene families associated with drought tolerance is therefore highly relevant. NAC transcription factors form a large plant-specific gene family involved in the regulation of tissue development and responses to biotic and abiotic stresses. The main goal of this study was to set up a framework of orthologous groups determined by an expert sequence comparison of NAC genes from both monocots and dicots. In order to clarify the orthologous relationships among NAC genes of different species, we performed an in-depth comparative study of four divergent taxa, in dicots and monocots, whose genomes have already been completely sequenced: Arabidopsis thaliana, Vitis vinifera, Musa acuminata and Oryza sativa. Due to independent evolution, NAC copy number is highly variable in these plant genomes. Based on an expert NAC sequence comparison, we propose forty orthologous groups of NAC sequences that were probably derived from an ancestor gene present in the most recent common ancestor of dicots and monocots. These orthologous groups provide a curated resource for large-scale protein sequence annotation of NAC transcription factors. The established orthology relationships also provide a useful reference for NAC function studies in newly sequenced genomes such as M. acuminata and other plant species.

Study of Post-Harvest Ambon Banana ( Musa acuminata ) Preservation Using X-Ray

International Nuclear Information System (INIS)

Dwijananti, P.; Handayani, L.; Marwoto, P.; Iswari, R.S.

2016-01-01

An exposure to Ambon banana ( Musa Acuminata ) samples has been done by using X-rays with current, voltage and exposure time are control parameters. This study aimed to determine storage ability of the post-harvest sample. Five samples were exposured by x-rays with the dose of (3-5) × 10 -14 Gy. The samples were stored at room temperature. Their mass and physical condition (color and smell) were evaluated every 3 days. It was found that the control sample which was not exposured by X-ray was ripe in the sixth day indicated by the yellow color and good smell of the banana. Meanwhile, the samples which were exposured by (3 - 5) × 10 -14 Gy doze of X-ray looked fresher and still had green color. These samples showed their ripening in the ninth day and their mass decrease was (12-13)% which is lower than the control sample. The preservation of banana can be done through low-dose X-ray exposure. (paper)

Aptitude of Lymnaea palustris and L. stagnalis to Fasciola hepatica larval development through the infection of several successive generations of 4-mm-high snails.

Science.gov (United States)

Vignoles, P; Rondelaud, D; Dreyfuss, G

2016-06-01

Bimiracidial infections of Lymnaea palustris and Lymnaea stagnalis (shell height at exposure, 4 mm) with Fasciola hepatica were carried out during six successive snail generations to determine if prevalence and intensity of snail infection increased over time through descendants issuing from eggs laid by parents already exposed to this digenean. Controls were constituted by a French population of Galba truncatula (a single generation) infected according to the same protocol. In a first experiment performed with the F1 to F5 generations of L. palustris, the prevalence and intensity of F. hepatica infection in snails progressively increased. Immature rediae and a few cercariae-containing rediae of the digenean were observed in L. stagnalis from the F3 generation, but no free cercaria was noted in the bodies of this lymnaeid from the F4 to F6 generations. In another experiment carried out with the F6 generation of L. palustris, the prevalence of F. hepatica infection and the number of shed cercariae were significantly lower in L. palustris than in G. truncatula. This mode of snail infection suggests an explanation for cases of human fasciolosis occurring in central France after the collection of wild watercress from beds where L. palustris was the sole lymnaeid.

Comparative anatomy of leaflets of Zamia acuminata and Z. pseudomonticola (Zamiaceae in Costa Rica

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Rafael Acuña-Castillo

2013-06-01

Full Text Available The genus Zamia is morphologically and ecologically the most diverse of the order Cycadales. Throughout its history this genus has been restricted to the New World and is presently almost entirely restricted to the Neotropics. Unusual anatomical traits of the leaflets, such as the sunken stomata and thick cuticle, are common in this and related genera. The objective of this research was to study and compare the leaflet anatomy of Zamia acuminata and Z. pseudomonticola and establish possible phylogenetic relationships between the anatomical traits and the near relatives of these species. The leaf material was obtained from living plants and then processed for electron microscopy study. We found that both species are very similar to each other and to Z. fairchildiana, and that they share several unusual traits with other species of the genus, such as the parenchyma morphology, the spatial distribution of tissues between the veins and the stomata morphology. The main differences between these species were seen in their fiber clusters and in the abundance of trichome basal cells on the epidermis. The anatomical similarities between the three species could be the result of their close phylogenetic relationship and the divergences between them could be the result of recent speciation during the Pleistocene, resulting from geological changes in Southern Costa Rica.Zamia es morfológica y ecológicamente el género más diverso del orden Cycadales. Este género siempre ha estado restringido a América, pero en la actualidad habita principalmente en la región neotropical. Características anatómicas inusuales en los foliolos como los estomas hundidos y las cutículas gruesas son comunes en Zamia y géneros afines. El objetivo de este trabajo consiste en comparar la anatomía de los foliolos de Zamia acuminata y Z. pseudomonticola y establecer posibles relaciones filogenéticas entre las características anatómicas y los parientes cercanos de esta

New and highly efficient column chromatographic extraction and simple purification of camptothecin from Camptotheca acuminata and Nothapodytes pittosporoides.

Science.gov (United States)

Zeng, Xue-Hua; Li, Yue-Hong; Wu, Shan-Shan; Hao, Rui-Lin; Li, Hui; Ni, He; Han, Han-Bing; Li, Hai-Hang

2013-01-01

Camptothecin, a widely used natural anti-cancer drug, is difficult to extract and purify effectively from plants. To develop new and highly efficient extraction and purification methods for analysis and production of camptothecin from leaves and fruits of Camptotheca acuminata and Nothapodytes pittosporoides roots. Dried materials were loaded in empty columns with fivefold 60% ethanol for leaves or 70% ethanol for fruits of C. acumnata, and sixfold 70% ethanol for N. pittosporoides roots. The columns were eluted with the same solvents at room temperature. Eluent was collected as extraction solution. Extraction solution from leaves and fruits of C. acuminata was vacuum-evaporated to remove ethanol, precipitated at pH 8.0 to remove alkaline insolubles and fractionated with chloroform at pH 3.0, which yields a crude product with 70% purity. Extraction solution from N. pittosporoides roots was concentrated to 1/10 volume and precipitated at pH 3.0, which yields a crude product with 60% purity. All crude products were purified by crystallisation. All steps were monitored by HPLC. Camptothecin was extracted from the three plant materials at a 98% rate with 15- or 18-fold solvent for content analysis, or at a 97% rate with five- or sixfold solvent for production. All crude products were purified to 98%. The overall recovery rates of camptothecin from plant materials to purified products reached 92% or higher. The new procedures are simple and highly efficient, and have multiple advantages for quantitative analysis and large production of camptothecin from plants. Copyright © 2013 John Wiley & Sons, Ltd.

Radiation dose assessment of musa acuminata - triploid (AAA)

International Nuclear Information System (INIS)

Maravillas, Mart Andrew S.; Locaylocay, Jocelyn R.; Mendoza, Concepcion S.

2008-01-01

Bananas are radioactive due to the presence of the radioisotope- 40 K. This imposes a possible health risk to the general public. This study intended to assess the annual equivalent dosages and the annual effective dosage committed by the body. This seeks to benefit the general public, students and researchers, and entrepreneurs. Using atomic absorption spectrophotometry, lakatan banana (Musa acuminata-triploid (AAA), the most purchased variety cultivated in Barangay Adlawon, Cebu City, Philippines, was found to contain 0.53 g of total potassium for every 100 g of its fresh fruit wherein 6.2 x 10 -5 g of which is potassium-40. Based on its 40 K content banana was calculated to have a radioactivity of 16 Bq/100 g. it was found out that the body is exposed to radiation dosages ranging from 2.8 x 10 -3 rem annually by eating 100 g of lakatan bananas everyday. Conversely, it is equivalent to the annual effective dosage of 0.0043 rem; the amount at which the body of an individual is uniformly exposed. However, no or extremely minute health risk was determined by just eating bananas. In fact, to exceed the radiation dose limits set by the International Commission on Radiation Protection, an individual may eat 116 kg of lakatan bananas everyday for a year. Fertilizers may be the major source of the radioisotope - 40 K and assimilated by the plants. (author)

Involvement of insulin-like peptide in long-term synaptic plasticity and long-term memory of the pond snail Lymnaea stagnalis.

Science.gov (United States)

Murakami, Jun; Okada, Ryuichi; Sadamoto, Hisayo; Kobayashi, Suguru; Mita, Koichi; Sakamoto, Yuki; Yamagishi, Miki; Hatakeyama, Dai; Otsuka, Emi; Okuta, Akiko; Sunada, Hiroshi; Takigami, Satoshi; Sakakibara, Manabu; Fujito, Yutaka; Awaji, Masahiko; Moriyama, Shunsuke; Lukowiak, Ken; Ito, Etsuro

2013-01-02

The pond snail Lymnaea stagnalis is capable of learning taste aversion and consolidating this learning into long-term memory (LTM) that is called conditioned taste aversion (CTA). Previous studies showed that some molluscan insulin-related peptides (MIPs) were upregulated in snails exhibiting CTA. We thus hypothesized that MIPs play an important role in neurons underlying the CTA-LTM consolidation process. To examine this hypothesis, we first observed the distribution of MIP II, a major peptide of MIPs, and MIP receptor and determined the amounts of their mRNAs in the CNS. MIP II was only observed in the light green cells in the cerebral ganglia, but the MIP receptor was distributed throughout the entire CNS, including the buccal ganglia. Next, when we applied exogenous mammalian insulin, secretions from MIP-containing cells or partially purified MIPs, to the isolated CNS, we observed a long-term change in synaptic efficacy (i.e., enhancement) of the synaptic connection between the cerebral giant cell (a key interneuron for CTA) and the B1 motor neuron (a buccal motor neuron). This synaptic enhancement was blocked by application of an insulin receptor antibody to the isolated CNS. Finally, injection of the insulin receptor antibody into the snail before CTA training, while not blocking the acquisition of taste aversion learning, blocked the memory consolidation process; thus, LTM was not observed. These data suggest that MIPs trigger changes in synaptic connectivity that may be correlated with the consolidation of taste aversion learning into CTA-LTM in the Lymnaea CNS.

Larval trematodes (Digenea) of the great pond snail, Lymnaea stagnalis (L.), (Gastropoda, Pulmonata) in Central Europe: a survey of species and key to their identification

Czech Academy of Sciences Publication Activity Database

Faltýnková, Anna; Našincová, Vanda; Kablásková, Lenka

2007-01-01

Roč. 14, č. 1 (2007), s. 39-51 ISSN 1252-607X R&D Projects: GA AV ČR IAA6022404; GA ČR GP524/07/P086; GA ČR GD524/03/H133; GA MŠk LC522 Institutional research plan: CEZ:AV0Z60220518 Keywords : Trematoda * Mollusca * cercaria * metacercaria * Lymnaea stagnalis Subject RIV: EG - Zoology Impact factor: 0.713, year: 2007

Cellular localisation of the anti-cancer drug camptothecin in Camptotheca acuminata Decne (Nyssaceae

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G Pasqua

2009-06-01

Full Text Available In Camptotheca acuminata, we studied the cellular sites of accumulation of the alkaloid camptothecin (CPT, in both plants grown in the field and those grown in a greenhouse, subjecting the latter to stress (i.e., draught, nutritional deficit, and pruning. Fresh sections of the leaf, stem, and root were analysed for the presence of CPT by examining the autofluorescence that the CPT molecule emits when exposed to UV radiation. In the plants grown in the field, CPT was observed only rarely. In the greenhouse plants, CPT had accumulated in crystalline form in the vacuole of specialised cells (i.e., segregator idioblasts, which were not morphologically distinguishable from the cells of the surrounding tissues. In the organs examined, the segregator idioblasts were localised in parenchymatic and epidermal tissues. CPT crystals were also detected in the glandular trichomes on both the stem and leaf.

Does water chemistry affect the dietary uptake and toxicity of silver nanoparticles by the freshwater snail Lymnaea stagnalis?

International Nuclear Information System (INIS)

Oliver, Ana López-Serrano; Croteau, Marie-Noële; Stoiber, Tasha L.; Tejamaya, Mila; Römer, Isabella; Lead, Jamie R.; Luoma, Samuel N.

2014-01-01

Silver nanoparticles (AgNPs) are widely used in many applications and likely released into the aquatic environment. There is increasing evidence that Ag is efficiently delivered to aquatic organisms from AgNPs after aqueous and dietary exposures. Accumulation of AgNPs through the diet can damage digestion and adversely affect growth. It is well recognized that aspects of water quality, such as hardness, affect the bioavailability and toxicity of waterborne Ag. However, the influence of water chemistry on the bioavailability and toxicity of dietborne AgNPs to aquatic invertebrates is largely unknown. Here we characterize for the first time the effects of water hardness and humic acids on the bioaccumulation and toxicity of AgNPs coated with polyvinyl pyrrolidone (PVP) to the freshwater snail Lymnaea stagnalis after dietary exposures. Our results indicate that bioaccumulation and toxicity of Ag from PVP-AgNPs ingested with food are not affected by water hardness and by humic acids, although both could affect interactions with the biological membrane and trigger nanoparticle transformations. Snails efficiently assimilated Ag from the PVP-AgNPs mixed with diatoms (Ag assimilation efficiencies ranged from 82 to 93%). Rate constants of Ag uptake from food were similar across the entire range of water hardness and humic acid concentrations. These results suggest that correcting regulations for water quality could be irrelevant and ineffective where dietary exposure is important. - Highlights: • AgNP coated with polyvinyl pyrrolidone (PVP), PVP-AgNP were efficiently assimilated by Lymnaea stagnalis. • Water chemistry has no influence on the dietary uptake of PVP-AgNP by snails. - L. Stagnalis assimilated PVP-AgNPs efficiently from food and water chemistry had no influence on their uptake and toxicity

Sympatric and allopatric combinations of Lymnaea columella and Fasciola hepatica from southern and south-eastern Brazil.

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Coelho, L H L; Lima, W S; Guimaraes, M P

2009-09-01

Experimental infections of Lymnaea columella with Fasciola hepatica were carried out to test the effect of sympatric and allopatric combinations between parasite and host, by using snails and flukes from southern and south-eastern Brazil. Four groups of 50 snails were infected with four miracidia per snail: two groups in sympatric and two groups in allopatric combinations. Sympatric combinations between parasite and host were more efficient than allopatric ones when snails from Itajubá were used, but the opposite was observed in infections involving snails from Pelotas. The sympatric association between L. columella and F. hepatica from Itajubá was significantly higher than in the other combinations. We concluded that the host-parasite relationship between L. columnella and F. hepatica may vary according to the geographical origin of the snails and flukes involved.

Rearing of Lymnaea columella (Say, 1817, intermediate host of Fasciola hepatica (Linnaeus, 1758

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Souza Cecília Pereira de

2000-01-01

Full Text Available The intermediate host of Fasciola hepatica, Lymnaea columella, collected in Belo Horizonte, Minas Gerais, Brazil, was reared in our laboratory. The aim of the current study was to standardize a rearing and maintenance technique. Two kinds of diet were tested: fresh lettuce (A and rodent ration + 10% CaCO3 plus fresh lettuce (B. The age for the beginning of oviposition ranged from 27 to 57 days. Ten days after oviposition at 24.7°C, 100% eclosion occurred. The complete life cycle varied from 37 to 67 days. The average numbers of eggs per egg mass were 26.3 and 31.1 with diets (A and (B, respectively. The lettuce and ration fed snails presented a increased growth although the difference was not statistically significant (p > 0.05. The mortality rate varied from 40 to 64% after 90 days. The maximum longevity was 183 days, 21.5 mm length and 11 mm wide. The methodology to mass breed and maintain these snails was found to be suitable in the laboratory

High voltage with little current as an unconditional stimulus for taste avoidance conditioning in Lymnaea stagnalis.

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Takigami, Satoshi; Sunada, Hiroshi; Lukowiak, Ken; Sakakibara, Manabu

2013-10-25

A new and better taste avoidance conditioning paradigm for Lymnaea has been developed that replaces the previously used tactile unconditional stimulus (US) with an brief electrical stimulus (1000V, 80μA), while continuing to use a sucrose application to the lips as the conditional stimulus (CS). With 15 paired CS-US presentations on a single day, we were able to elicit both short-term memory (STM) and long-term memory (LTM). The LTM persisted for at least one week. While STM was elicited with 5, 8, or 10 paired presentations of the CS-US on a single day, LTM was not. The new US used here was more consistent than the previously used US, and this stimulus consistency may explain why 15 paired CS-US presentations now result in LTM formation. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

First report of Lymnaea columella Say, 1817 (Pulmonata: Lymnaeidae naturally infected with Fasciola hepatica (Linnaeus,1758 (Trematoda: Digenea in Argentina

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Prepelitchi Lucila

2003-01-01

Full Text Available We report the first evidence of natural infection of Lymnaea columella with Fasciola hepatica in Argentina. A sample of 601 snails was collected in May 2003 in northeastern Corrientes, a province bounded on the north by Paraguay, on the east by Brazil and on the southeast by Uruguay. Among 500 examined snails, 44 (8.8% were exclusively infected with F. hepatica. Parasite identification was based on morphological features of cercariae from snails, and of eggs and adult flukes from Wistar rats. We discuss the events suggesting that an enzootic transmission cycle of F. hepatica has been recently established in northeastern Corrientes.

Reversal of age-related learning deficiency by the vertebrate PACAP and IGF-1 in a novel invertebrate model of aging: the pond snail (Lymnaea stagnalis).

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Pirger, Zsolt; Naskar, Souvik; László, Zita; Kemenes, György; Reglődi, Dóra; Kemenes, Ildikó

2014-11-01

With the increase of life span, nonpathological age-related memory decline is affecting an increasing number of people. However, there is evidence that age-associated memory impairment only suspends, rather than irreversibly extinguishes, the intrinsic capacity of the aging nervous system for plasticity (1). Here, using a molluscan model system, we show that the age-related decline in memory performance can be reversed by administration of the pituitary adenylate cyclase activating polypeptide (PACAP). Our earlier findings showed that a homolog of the vertebrate PACAP38 and its receptors exist in the pond snail (Lymnaea stagnalis) brain (2), and it is both necessary and instructive for memory formation after reward conditioning in young animals (3). Here we show that exogenous PACAP38 boosts memory formation in aged Lymnaea, where endogenous PACAP38 levels are low in the brain. Treatment with insulin-like growth factor-1, which in vertebrates was shown to transactivate PACAP type I (PAC1) receptors (4) also boosts memory formation in aged pond snails. Due to the evolutionarily conserved nature of these polypeptides and their established role in memory and synaptic plasticity, there is a very high probability that they could also act as "memory rejuvenating" agents in humans. © The Author 2014. Published by Oxford University Press on behalf of The Gerontological Society of America.

Actividad molusquicida del Paraiso (Melia azedarach L. (Meliaceae sobre Lymnaea cubensis, molusco vector de Fasciolosis Molluscicidal activity of Paraiso (Melia azedarach L. (Meliaceae on Lymnaea cubensis, host snail of Fasciolosis

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Marlene Piña Perez

1998-06-01

Full Text Available INTRODUCCIÓN: La Fasciolosis constituye en diversas regiones una fuente importante de pérdidas económicas y cuando se descuidan las medidas de control de sus hospedadores (moluscos, junto a condiciones ecológicas favorables, pueden ocurrir casos aislados de Fasciolosis humana. Dentro de los métodos alternativos para su control está el uso de extractos vegetales y se pretendió evaluar el probable empleo del jugo extraído del fruto y semillas del Paraiso (Melia azedarach L. en el control de Lymnaea cubensis, principal vector de la Fasciolosis en Cuba. MATERIAL Y MÉTODO: Diferentes concentraciones del jugo extraído del fruto y semillas del Paraiso (Melia azedarach L. fueron testados para determinar las dosis letales media (DL50 y máxima (DL90 usando un programa computarizado Probit-Log. Siete series experimentales fueron probadas usando 72 moluscos en cada una. Para determinar la influencia sobre la frecuencia cardíaca fueron testados tres grupos de 10 moluscos, dos fueron tratados con las DL50=0,88627 y DL90=1,7641, respectivamente, mientras que el tercero fue considerado como testigo. RESULTADOS Y CONCLUSIONES: Se observó una marcada influencia de ambas dosis sobre la frecuencia cardíaca del molusco estudiado. Estos resultados son alentadores, pues demuestran el potencial empleo de esta planta en el control de moluscos indeseables.INTRODUÇÃO: A Fasciolosis constitui em diversas regiões fonte importante de perdas econômicas, e quando não se adotam medidas de controle de seus hospedeiros (moluscos, junto a condições ecológicas favoráveis, pode ocorrer o aparecimento de casos isolados de Fasciolosis humana. Dentro dos métodos alternativos para o seu controle está o uso de extratos vegetais e se tem pretendido avaliar o provável emprego do suco extraído do fruto e sementes do Paraíso (Melia azedarach L., no controle de Lymnaea cubensis, principal vetor da Fasciolosis em Cuba. MATERIAL E MÉTODO: Diferentes concentra

Susceptibilidade de Lymnaea (pseudosuccinea columella (Say, 1817 exposta à infecção por miracídios de Fasciola hepatica (Linnaeus, 1758

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Alfredo Raimundo Corrêa Dacal

1988-10-01

Full Text Available Com o objetivo de estudar a susceptibilidade de Lymnaea (pseudosuccinea columella de Minas Gerais, Estado onde ainda não se registraram casos autóctones de fasciolose hepática, foram utilizadas as amostras MG 1, MG 2, MG 3 e MG 4, provenientes de diferentes regiões deste Estado, para estudo comparativo com as amostras RJ e RGS procedentes dos Estados do Rio de Janeiro e Rio Grande do Sul, áreas de focos de fasciolose. A amostra de Fasciola hepatica utilizada era procedente de ovinos abatidos no município de Camapuã, no Rio Grande do Sul, e foi mantida em coelhos. Os moluscos foram infectados com 6, 8 e 10 miracídos por molusco, sendo estudadas as incidências de infecção e de mortalidade. Nas condições que se realizou o trabalho diante dos resultados obtidos, foram tiradas as seguintes conclusões: 1. A mortalidade dos caramujos parece não estar diretamente relacionada com a percentagem de infecção; 2. As amostras de Lymnaea (pseudosuccinea columella de Minas Gerais, do Rio de Janeiro e do Rio Grande do Sul mostraram-se identicamente susceptíveis à infecção por Fasciola hepatica; 3. A população humana e os rebanhos bovino, ovino e suíno de Minas Gerais, particularmente aqueles do Vale do Rio Paraíba, podem ser considerados sujeitos à infecção por Fasciola hepatica.

Prevalence of Fasciola in cattle and of its intermediate host Lymnaea snails in central Vietnam.

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Nguyen, Sam Thi; Nguyen, Duc Tan; Van Nguyen, Thoai; Huynh, Vu Vy; Le, Duc Quyet; Fukuda, Yasuhiro; Nakai, Yutaka

2012-12-01

The aims of this study were to investigate the prevalence of natural Fasciola infections in both the definitive hosts (cattle) and the intermediate hosts (Lymnaea snails) in central Vietnam. A total of 1,075 fecal samples, randomly collected from cattle in Binh Dinh, Khanh Hoa, and Phu Yen provinces, were examined for Fasciola eggs by a sedimentation method. The overall prevalence of Fasciola was 45.3 %. A subset of the animals (235) was also screened for antibodies against Fasciola by an enzyme-linked immunosorbent assay. Overall, 46.3 % of these animals were shedding Fasciola eggs while 87.2 % were Fasciola seropositive. A lower prevalence of Fasciola was observed in calves ≤ 2 years of age (37.6 %) compared to that in cattle >2 years of age (53.7 %) (p Fasciola. This appears to be the first epidemiological survey of the prevalence of Fasciola in cattle and snails in these three provinces in central Vietnam.

Protein kinase C mediates memory consolidation of taste avoidance conditioning in Lymnaea stagnalis.

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Takigami, Satoshi; Sunada, Hiroshi; Lukowiak, Ken; Kuzirian, Alan M; Alkon, Daniel L; Sakakibara, Manabu

2014-05-01

In Lymnaea stagnalis, in order to obtain a 10 min short-term memory (STM) of taste avoidance conditioning (TAC) at least 10 paired presentations of a conditioned stimulus (CS), sucrose, and an unconditioned stimulus (US), tactile stimulation to the animal's head, are required. Pre-exposure of snails to the protein kinase C (PKC) α and ε activator bryostatin (Bryo) facilitated STM formation in that only 5 paired CS-US trials were required. Typically 20 paired presentations of the CS-US are required for formation of STM and LTM. However, 20 paired presentations do not result in STM or LTM if snails are pre-incubated with a PKC inhibitor, Ro-32-0432. We also found that LTM lasting longer than 48 h was acquired with Bryo incubation for 45 min even after termination of the conditioning paradigm. These data suggest that activation of the α and ε isozymes of PKC is crucially involved in the formation of LTM and provide further support for a mechanism that has been conserved across the evolution of species ranging from invertebrate molluscs to higher mammals. Copyright © 2014 Elsevier Inc. All rights reserved.

Critical period of memory enhancement during taste avoidance conditioning in Lymnaea stagnalis.

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Takahashi, Tomoyo; Takigami, Satoshi; Sunada, Hiroshi; Lukowiak, Ken; Sakakibara, Manabu

2013-01-01

The present study investigated the optimal training procedure leading to long-lasting taste avoidance behavior in Lymnaea. A training procedure comprising 5 repeated pairings of a conditional stimulus (CS, sucrose), with an unconditional stimulus (US, a tactile stimulation to the animal's head), over a 4-day period resulted in an enhanced memory formation than 10 CS-US repeated pairings over a 2-day period or 20 CS-US repeated pairings on a single day. Backward conditioning (US-CS) pairings did not result in conditioning. Thus, this taste avoidance conditioning was CS-US pairing specific. Food avoidance behavior was not observed following training, however, if snails were immediately subjected to a cold-block (4°C for 10 min). It was critical that the cold-block be applied within 10 min to block long-term memory (LTM) formation. Further, exposure to the cold-block 180 min after training also blocked both STM and LTM formation. The effects of the cold-block on subsequent learning and memory formation were also examined. We found no long lasting effects of the cold-block on subsequent memory formation. If protein kinase C was activated before the conditioning paradigm, snails could still acquire STM despite exposure to the cold-block.

Critical period of memory enhancement during taste avoidance conditioning in Lymnaea stagnalis.

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Tomoyo Takahashi

Full Text Available The present study investigated the optimal training procedure leading to long-lasting taste avoidance behavior in Lymnaea. A training procedure comprising 5 repeated pairings of a conditional stimulus (CS, sucrose, with an unconditional stimulus (US, a tactile stimulation to the animal's head, over a 4-day period resulted in an enhanced memory formation than 10 CS-US repeated pairings over a 2-day period or 20 CS-US repeated pairings on a single day. Backward conditioning (US-CS pairings did not result in conditioning. Thus, this taste avoidance conditioning was CS-US pairing specific. Food avoidance behavior was not observed following training, however, if snails were immediately subjected to a cold-block (4°C for 10 min. It was critical that the cold-block be applied within 10 min to block long-term memory (LTM formation. Further, exposure to the cold-block 180 min after training also blocked both STM and LTM formation. The effects of the cold-block on subsequent learning and memory formation were also examined. We found no long lasting effects of the cold-block on subsequent memory formation. If protein kinase C was activated before the conditioning paradigm, snails could still acquire STM despite exposure to the cold-block.

Strain-specific differences of the effects of stress on memory in Lymnaea.

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Hughes, Emily; Shymansky, Tamila; Swinton, Erin; Lukowiak, Kai S; Swinton, Cayley; Sunada, Hiroshi; Protheroe, Amy; Phillips, Iain; Lukowiak, Ken

2017-03-01

Stress alters the ability to form, recall and maintain memory according to the Yerkes-Dodson/Hebb (YDH) law. The effects of environmentally relevant stressors, such as low environmental calcium and crowding, on learning and memory have previously been described in a laboratory-reared 'average' strain of Lymnaea stagnalis (i.e. the Dutch strain) as well as two strains of freshly collected L . stagnalis with enhanced memory formation abilities (i.e. 'smart' snails). Here, we use L . stagnalis to study the effects of other environmentally relevant stressors on memory formation in two other strains of freshly collected snails, one 'smart' and one 'average'. The stressors we examined are thermal, resource restriction combined with food odour, predator detection and, for the first time, tissue injury (shell damage). We show that the same stressor has significantly different effects on memory formation depending on whether snails are 'smart' or 'average'. Specifically, our data suggest that a stressor or a combination of stressors act to enhance memory in 'average' snails but obstruct memory formation in 'smart' snails. These results are consistent with the YDH law and our hypothesis that 'smart' snails are more easily stressed than 'average' snails. © 2017. Published by The Company of Biologists Ltd.

In vitro PHYTOTHERAPY OF VECTOR SNAILS BY BINARY COMBINATIONS OF LARVICIDAL ACTIVE COMPONENTS IN EFFECTIVE CONTROL OF FASCIOLIASIS

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Kumari Sunita

2013-09-01

Full Text Available SUMMARY A food-borne trematode infection fascioliasis is one among common public health problems worldwide. It caused a great economic loss for the human race. Control of snail population below a certain threshold level is one of the important methods in the campaign to reduce the incidence of fascioliasis. The life cycle of the parasite can be interrupted by killing the snail or Fasciola larva redia and cercaria inside of the snail Lymnaea acuminata. In vitro toxicity of different binary combinations (1:1 ratio of plant-derived larvicidal active components such as citral, ferulic acid, umbelliferone, azadirachtin and allicin against Fasciola redia and cercaria were tested. The mortality of larvae was observed at 2h, 4h, 6h and 8h of treatment. In in vitro condition azadirachtin + allicin (1:1 ratio was highly toxic against redia and cercaria (8h LC50 0.006 and 0.005 mg/L. Toxicity of citral + ferulic acid was lowest against redia and cercaria larvae.

In vitro propagation and assessment of the genetic fidelity of Musa acuminata (AAA) cv. Vaibalhla derived from immature male flowers.

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Hrahsel, Lalremsiami; Basu, Adreeja; Sahoo, Lingaraj; Thangjam, Robert

2014-02-01

An efficient in vitro propagation method has been developed for the first time for Musa acuminata (AAA) cv. Vaibalhla, an economically important banana cultivar of Mizoram, India. Immature male flowers were used as explants. Murashige and Skoog's (MS) medium supplemented with plant growth regulators (PGRs) were used for the regeneration process. Out of different PGR combinations, MS medium supplemented with 2 mg L(-1) 6-benzylaminopurine (BAP) + 0.5 mg L(-1) α-naphthalene acetic acid (NAA) was optimal for production of white bud-like structures (WBLS). On this medium, explants produced the highest number of buds per explant (4.30). The highest percentage (77.77) and number (3.51) of shoot formation from each explants was observed in MS medium supplemented with 2 mg L(-1) kinetin + 0.5 mg L(-1) NAA. While MS medium supplemented with a combination of 2 mg L(-1) BAP + 0.5 mg L(-1) NAA showed the maximum shoot length (14.44 cm). Rooting efficiency of the shoots was highest in the MS basal medium without any PGRs. The plantlets were hardened successfully in the greenhouse with 96% survival rate. Random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) markers were employed to assess the genetic stability of in vitro regenerated plantlets of M. acuminata (AAA) cv. Vaibalhla. Eight RAPD and 8 ISSR primers were successfully used for the analysis from the 40 RAPD and 30 ISSR primers screened initially. The amplified products were monomorphic across all the regenerated plants and were similar to the mother plant. The present standardised protocol will find application in mass production, conservation and genetic transformation studies of this commercially important banana.

The bioavailability of the transuranic elements 237Pu and 241Am for the pond snail, Lymnaea stagnalis L., and their behaviour in selected natural surface waters

International Nuclear Information System (INIS)

Thiels, G.M.

1983-01-01

An attempt was made to characterise the bioavailability of 237 Pu and 241 Am for the pond snail Lymnaea stagnalis L. in selected surface waters. The uptake, distribution and retention patterns were studied through the contamination route water-snail. The effects of a number of parameters, such as seasonal variation, water type (pH, conductivity, ionic composition) and presence of food, on the bioavailability of the transuranics were evaluated. Finally, an assessment was made concerning the chemical speciation of plutonium and americium in the selected freshwaters

Crystal structures of Lymnaea stagnalis AChBP in complex with neonicotinoid insecticides imidacloprid and clothianidin.

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Ihara, Makoto; Okajima, Toshihide; Yamashita, Atsuko; Oda, Takuma; Hirata, Koichi; Nishiwaki, Hisashi; Morimoto, Takako; Akamatsu, Miki; Ashikawa, Yuji; Kuroda, Shun'ichi; Mega, Ryosuke; Kuramitsu, Seiki; Sattelle, David B; Matsuda, Kazuhiko

2008-06-01

Neonicotinoid insecticides, which act on nicotinic acetylcholine receptors (nAChRs) in a variety of ways, have extremely low mammalian toxicity, yet the molecular basis of such actions is poorly understood. To elucidate the molecular basis for nAChR-neonicotinoid interactions, a surrogate protein, acetylcholine binding protein from Lymnaea stagnalis (Ls-AChBP) was crystallized in complex with neonicotinoid insecticides imidacloprid (IMI) or clothianidin (CTD). The crystal structures suggested that the guanidine moiety of IMI and CTD stacks with Tyr185, while the nitro group of IMI but not of CTD makes a hydrogen bond with Gln55. IMI showed higher binding affinity for Ls-AChBP than that of CTD, consistent with weaker CH-pi interactions in the Ls-AChBP-CTD complex than in the Ls-AChBP-IMI complex and the lack of the nitro group-Gln55 hydrogen bond in CTD. Yet, the NH at position 1 of CTD makes a hydrogen bond with the backbone carbonyl of Trp143, offering an explanation for the diverse actions of neonicotinoids on nAChRs.

Optimizing the design of a reproduction toxicity test with the pond snail Lymnaea stagnalis.

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Charles, Sandrine; Ducrot, Virginie; Azam, Didier; Benstead, Rachel; Brettschneider, Denise; De Schamphelaere, Karel; Filipe Goncalves, Sandra; Green, John W; Holbech, Henrik; Hutchinson, Thomas H; Faber, Daniel; Laranjeiro, Filipe; Matthiessen, Peter; Norrgren, Leif; Oehlmann, Jörg; Reategui-Zirena, Evelyn; Seeland-Fremer, Anne; Teigeler, Matthias; Thome, Jean-Pierre; Tobor Kaplon, Marysia; Weltje, Lennart; Lagadic, Laurent

2016-11-01

This paper presents the results from two ring-tests addressing the feasibility, robustness and reproducibility of a reproduction toxicity test with the freshwater gastropod Lymnaea stagnalis (RENILYS strain). Sixteen laboratories (from inexperienced to expert laboratories in mollusc testing) from nine countries participated in these ring-tests. Survival and reproduction were evaluated in L. stagnalis exposed to cadmium, tributyltin, prochloraz and trenbolone according to an OECD draft Test Guideline. In total, 49 datasets were analysed to assess the practicability of the proposed experimental protocol, and to estimate the between-laboratory reproducibility of toxicity endpoint values. The statistical analysis of count data (number of clutches or eggs per individual-day) leading to ECx estimation was specifically developed and automated through a free web-interface. Based on a complementary statistical analysis, the optimal test duration was established and the most sensitive and cost-effective reproduction toxicity endpoint was identified, to be used as the core endpoint. This validation process and the resulting optimized protocol were used to consolidate the OECD Test Guideline for the evaluation of reproductive effects of chemicals in L. stagnalis. Copyright © 2016 Elsevier Inc. All rights reserved.

SOURCES OF MYCORRHIZAL INFECTION OF SHOREA ACUMINATA SEEDLINGS UNDER LABORATORY CONDITIONS

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LEE Su SEE

1995-01-01

Full Text Available Uninoculated dipterocarp seedlings raised in normal field soil in nurseries were always found to have mycorrhizas after a few months. This study set out to determine whether dipterocarp seedlings could continue to grow and develop in the absence of mycorrhizas and also to determine possible sources of mycorrhizal infection of dipterocarp seedlings raised under laboratory conditions using Shorea acuminata as a typical example. Seedlings were planted in capped or uncapped perspex boxes containing sterile or non-sterile field soil and watered daily with sterile water or tap water. Seedling growth and development of mycorrhizas were monitored at monthly intervals for up to seven months. Seedlings grown in sterile soil remained uninfected after seven months while infection was found in some of the seedlings grown in normal soil regardless of whether they had been watered with tap water or sterile water. This showed that field soil (i.e. under grass far from the forest contained suitable inoculum for forest tree seedlings. Tap water and the air were not important sources of infection. However, mycorrhizal infection was very uneven indicating that the inoculum was probably very unevenly distributed in the soil or that the inoculum density was rather low. Seedlings grown in sterile soil showed better growth than those grown in normal soil and infection of roots by parasitic fungi in the latter was also observed.

The banana (Musa acuminata) genome and the evolution of monocotyledonous plants.

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D'Hont, Angélique; Denoeud, France; Aury, Jean-Marc; Baurens, Franc-Christophe; Carreel, Françoise; Garsmeur, Olivier; Noel, Benjamin; Bocs, Stéphanie; Droc, Gaëtan; Rouard, Mathieu; Da Silva, Corinne; Jabbari, Kamel; Cardi, Céline; Poulain, Julie; Souquet, Marlène; Labadie, Karine; Jourda, Cyril; Lengellé, Juliette; Rodier-Goud, Marguerite; Alberti, Adriana; Bernard, Maria; Correa, Margot; Ayyampalayam, Saravanaraj; Mckain, Michael R; Leebens-Mack, Jim; Burgess, Diane; Freeling, Mike; Mbéguié-A-Mbéguié, Didier; Chabannes, Matthieu; Wicker, Thomas; Panaud, Olivier; Barbosa, Jose; Hribova, Eva; Heslop-Harrison, Pat; Habas, Rémy; Rivallan, Ronan; Francois, Philippe; Poiron, Claire; Kilian, Andrzej; Burthia, Dheema; Jenny, Christophe; Bakry, Frédéric; Brown, Spencer; Guignon, Valentin; Kema, Gert; Dita, Miguel; Waalwijk, Cees; Joseph, Steeve; Dievart, Anne; Jaillon, Olivier; Leclercq, Julie; Argout, Xavier; Lyons, Eric; Almeida, Ana; Jeridi, Mouna; Dolezel, Jaroslav; Roux, Nicolas; Risterucci, Ange-Marie; Weissenbach, Jean; Ruiz, Manuel; Glaszmann, Jean-Christophe; Quétier, Francis; Yahiaoui, Nabila; Wincker, Patrick

2012-08-09

Bananas (Musa spp.), including dessert and cooking types, are giant perennial monocotyledonous herbs of the order Zingiberales, a sister group to the well-studied Poales, which include cereals. Bananas are vital for food security in many tropical and subtropical countries and the most popular fruit in industrialized countries. The Musa domestication process started some 7,000 years ago in Southeast Asia. It involved hybridizations between diverse species and subspecies, fostered by human migrations, and selection of diploid and triploid seedless, parthenocarpic hybrids thereafter widely dispersed by vegetative propagation. Half of the current production relies on somaclones derived from a single triploid genotype (Cavendish). Pests and diseases have gradually become adapted, representing an imminent danger for global banana production. Here we describe the draft sequence of the 523-megabase genome of a Musa acuminata doubled-haploid genotype, providing a crucial stepping-stone for genetic improvement of banana. We detected three rounds of whole-genome duplications in the Musa lineage, independently of those previously described in the Poales lineage and the one we detected in the Arecales lineage. This first monocotyledon high-continuity whole-genome sequence reported outside Poales represents an essential bridge for comparative genome analysis in plants. As such, it clarifies commelinid-monocotyledon phylogenetic relationships, reveals Poaceae-specific features and has led to the discovery of conserved non-coding sequences predating monocotyledon-eudicotyledon divergence.

Memory, reconsolidation and extinction in Lymnaea require the soma of RPeD1.

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Sangha, Susan; Varshney, Nishi; Fras, Mary; Smyth, Kim; Rosenegger, David; Parvez, Kashif; Sadamoto, Hisayo; Lukowiak, Ken

2004-01-01

The central pattern generator (CPG) that drives aerial respiratory behaviour in Lymnaea consists of 3 neurons. One of these, RPeD1--the cell that initiates activity in the circuit, plays an absolutely necessary role as a site for memory formation, memory reconsolidation, and extinction. Using an operant conditioning training procedure that results in a long-term non-declarative memory (LTM), we decrease the occurrence of aerial respiratory behaviour. Since snails can still breathe cutaneously learning this procedure is not harmful. Concomitant with behavioural memory are changes in the spiking activity of RPeD1. Going beyond neural correlates of memory we directly show that RPeD1 is a necessary site for LTM formation. Expanding on this finding we show that this neuron is also a necessary site for memory reconsolidation and 'Pavlovian' extinction. As far as we can determine, this is the first time a single neuron has been shown to be a necessary site for these different aspects memory. RPeD1 is thus a key neuron mediating different hierarchical aspects of memory. We are now in a position to determine the necessary neuronal, molecular and proteomic events in this neuron that are causal to memory formation, reconsolidation and extinction.

Evolutionary implications of a high selfing rate in the freshwater snail Lymnaea truncatula.

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Trouvé, S; Degen, L; Renaud, F; Goudet, J

2003-10-01

Self-compatible hermaphroditic organisms that mix self-fertilization and outcrossing are of great interest for investigating the evolution of mating systems. We investigate the evolution of selfing in Lymnaea truncatula, a self-compatible hermaphroditic freshwater snail. We first analyze the consequences of selfing in terms of genetic variability within and among populations and then investigate how these consequences along with the species ecology (harshness of the habitat and parasitism) might govern the evolution of selfing. Snails from 13 localities (classified as temporary or permanent depending on their water availability) were sampled in western Switzerland and genotyped for seven microsatellite loci. F(IS) (estimated on adults) and progeny array analyses (on hatchlings) provided similar selfing rate estimates of 80%. Populations presented a low polymorphism and were highly differentiated (F(ST) = 0.58). Although the reproductive assurance hypothesis would predict higher selfing rate in temporary populations, no difference in selfing level was observed between temporary and permanent populations. However, allelic richness and gene diversity declined in temporary habitats, presumably reflecting drift. Infection levels varied but were not simply related to either estimated population selfing rate or to differences in heterozygosity. These findings and the similar selfing rates estimated for hatchlings and adults suggest that within-population inbreeding depression is low in L. truncatula.

Cell-specific expression of tryptophan decarboxylase and 10-hydroxygeraniol oxidoreductase, key genes involved in camptothecin biosynthesis in Camptotheca acuminata Decne (Nyssaceae

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Santamaria Anna

2010-04-01

Full Text Available Abstract Background Camptotheca acuminata is a major natural source of the terpenoid indole alkaloid camptothecin (CPT. At present, little is known about the cellular distribution of the biosynthesis of CPT, which would be useful knowledge for developing new strategies and technologies for improving alkaloid production. Results The pattern of CPT accumulation was compared with the expression pattern of some genes involved in CPT biosynthesis in C. acuminata [i.e., Ca-TDC1 and Ca-TDC2 (encoding for tryptophan decarboxylase and Ca-HGO (encoding for 10-hydroxygeraniol oxidoreductase]. Both CPT accumulation and gene expression were investigated in plants at different degrees of development and in plantlets subjected to drought-stress. In all organs, CPT accumulation was detected in epidermal idioblasts, in some glandular trichomes, and in groups of idioblast cells localized in parenchyma tissues. Drought-stress caused an increase in CPT accumulation and in the number of glandular trichomes containing CPT, whereas no increase in epidermal or parenchymatous idioblasts was observed. In the leaf, Ca-TDC1 expression was detected in some epidermal cells and in groups of mesophyll cells but not in glandular trichomes; in the stem, it was observed in parenchyma cells of the vascular tissue; in the root, no expression was detected. Ca-TDC2 expression was observed exclusively in leaves of plantlets subjected to drought-stress, in the same sites described for Ca-TDC1. In the leaf, Ca-HGO was detected in all chlorenchyma cells; in the stem, it was observed in the same sites described for Ca-TDC1; in the root, no expression was detected. Conclusions The finding that the sites of CPT accumulation are not consistently the same as those in which the studied genes are expressed demonstrates an organ-to-organ and cell-to-cell translocation of CPT or its precursors.

Post harvest changes of banana prata (Musa acuminata x Musa balbisiana group AAB) {gamma}-irradiated; Modificacoes pos-colheita de banana prata (Musa acuminata x Musa balbisiana grupo AAB) {gamma}-irradiada

Energy Technology Data Exchange (ETDEWEB)

Barros Villas Boas, Eduardo Valerio de

1995-12-31

Pre-climateric bananas (Musa acuminata x Musa balbisiana [AAB group] cv. Prata) were stored without treatment (no radiation) or were exposed at 0.25 and 0.50 kGy of {gamma} -irradiation, with a dose rate of 1 kGy.h {sup -1} before storage. The fruits were analysed for CO{sub 2} and ethylene production during maturation and pulp-to-peel ratio, starch, total soluble sugars, pectins, pectin methyl esterase and poly galacturonase activities on 6 colour score of peel. The radiation dose/peel-colour interaction affected the pulp-to-peel ratio significantly, while the fruits subjected at 0.25 Gy had the highest increase on the colour scores 5, 6, and 7. A predictable increase in the conversion of starch to sugar took place during maturation and a delaying on the soluble sugar accumulation was noted on the fruits submitted to 0.50 kGy, in the 6 and 7 colour scores only. A decrease on the total pectin content and a trend of a higher solubilization of pectins was observed in the fruits {gamma}-irradiated at 0.50 kGy. Higher pectin methyl esterase activities were exhibited by irradiated fruits, although the {gamma}-irradiation has suppressed the poly galacturonase activity throughout the maturation period. (author). 110 refs., 11 figs., 5 tabs.

Sensory mediation of memory blocking stressors in the pond snail Lymnaea stagnalis.

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Dalesman, Sarah; Karnik, Vikram; Lukowiak, Ken

2011-08-01

The great pond snail, Lymnaea stagnalis, is commonly used as a model species to study how stress affects the ability to form long-term memory (LTM); however, we still have little information about how the snail senses stressful stimuli. The osphradium is an external sensory organ that demonstrates electrophysiological responses to a variety of external chemical stimuli. We examined the role, if any, played by the osphradium in sensing two environmental stressors, crowding and low environmental calcium, both known to block LTM in intact animals. We severed the osphradial nerve, blocking external sensory input from this organ to the central nervous system, and then exposed the snails to low environmental calcium or crowding stress to assess whether these stressors continued to block LTM formation. When exposed to low environmental calcium, snails with their osphradial nerve severed responded as if they were maintained in our standard calcium environment. That is, they did not respond to low calcium as a stressor blocking LTM; therefore, the osphradium plays a crucial role in mediating how snails respond to this stressor. However, following crowding, LTM formation was blocked in both control groups and snails that had the osphradial nerve severed, indicating that sensory information from the osphradium is not required to sense crowded conditions. Together these data show that two stressors that result in the same behavioural phenotype, blocking LTM formation, do so via two distinct sensory pathways.

Baseline growth and reproductive parameters in Lymnaea stagnalis for OECD test guideline development: optimization of diets and culturing conditions

DEFF Research Database (Denmark)

Holbech, Henrik; Hutchinson, Tom

laboratories in Denmark, Germany and the UK for the OECD pre-validation work to date. Laboratory cultures of L. stagnalis are traditionally fed fresh (preferably organic) lettuce; however, interrupted supplies of fresh lettuce in some countries in 2011 highlighted a potential problem for the draft OECD test...... of a mollusc reproduction test guideline. An ad hoc mollusc expert group has been formed in Europe to validate methods that can meet this need. Currently, a key species for use in this context is the freshwater gastropod Lymnaea stagnalis. An important aspect of this work is to first develop a specific...... pathogen free defined strain of L. stagnalis and second to establish a historical database of growth and reproductive rates under defined culturing conditions. A mass culture of the RENILYS® strain of L. stagnalis have been established at INRA (France) since 2002 and has been distributed to research...

Lipoidal Labellar Secretions in Maxillaria Ruiz & Pav. (Orchidaceae)

OpenAIRE

DAVIES, K. L.; TURNER, M. P.; GREGG, A.

2003-01-01

The labella of Maxillaria acuminata Lindl., M. cerifera Barb. Rodr. and M. notylioglossa Rchb.f., all members of the M. acuminata alliance, produce a viscid wax‐like secretion. Histochemical analysis revealed that the chemical composition of the secretion is similar in all three species, consisting largely of lipid and protein. Light microscopy and low‐vacuum scanning electron microscopy were used to investigate the secretory process. In a fourth taxon, M. cf. notylioglossa, transmission elec...

Size-related flowering and fecundity in the tropical canopy tree species, Shorea acuminata (Dipterocarpaceae) during two consecutive general flowerings.

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Naito, Yoko; Kanzaki, Mamoru; Numata, Shinya; Obayashi, Kyoko; Konuma, Akihiro; Nishimura, Sen; Ohta, Seiichi; Tsumura, Yoshihiko; Okuda, Toshinori; Lee, Soon Leong; Muhammad, Norwati

2008-01-01

We monitored the reproductive status of all trees with diameters at breast height (dbh) >30 cm in a 40-ha plot at Pasoh, west Malaysia, and investigated the individual fecundity of 15 Shorea acuminata Dyer (Dipterocarpaceae) trees using seed-trapping methods during two consecutive general flowering periods in 2001 (GF2001) and 2002 (GF2002). The proportion of flowering trees was higher, and not dependent on size, in GF2002 (84.2%), than in GF2001 (54.5%), when flowering mainly occurred in trees with a dbh investment during the two consecutive reproductive events clearly differed between medium-sized and large trees; the former concentrated their reproductive investment in one of the reproductive events whereas the latter allocated their investment more evenly to both reproductive events. Our results suggest size-related differences in the resource allocation pattern for reproduction.

Silver nanoparticles alter learning and memory formation in an aquatic organism, Lymnaea stagnalis.

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Young, Austin; Protheroe, Amy; Lukowiak, Ken

2017-06-01

We tested the effect of silver nanoparticles (AgNPs) on the ability of the pond snail, Lymnaea stagnalis, to learn and form long-term memory (LTM) following operant conditioning of aerial respiration. We hypothesized that the AgNPs would act as a stressor and prevent learning and LTM formation. We tested snails exposed for either 72 h or only during training and testing for memory (i.e. 0.5 h) and found no difference between those treatments. We found that at a low concentration of AgNPs (5 μg/L) neither learning and nor memory formation were altered. When we increased the concentration of AgNPs (10 μg/L) we found that memory formation was enhanced. Finally, at a higher concentration (50 μg/L) memory formation was blocked. To determine if the disassociation of Ag + from the AgNPs caused the effects on memory we performed similar experiments with AgNO 3 and found similar concentration-dependent results. Finally, we found that snails perceive the AgNPs differently from Ag+ as there was context specific memory. That is, snails trained in AgNPs did not show memory when tested in Ag + and vice-versa. We believe that changes in memory formation may be a more sensitive determination of AgNPs on aquatic organisms than the determination of a LC 50 . Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Dynamic of population-dynamics in a medically important snail species Lymnaea (Radix Luteola (Lamarck

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T. K. Misra

1993-09-01

Full Text Available The life-cycle parameters of the snail Lymnaea (Radix luteola and the factors influencing the same have been studied under laboratory conditions. Ins each month, from July 1990 to June 1991, a batch of 100 zero-day old individual were considered for studies. The snails of April batch survived for 19.42 days while those in December batch survived for 87.45 days. The May batch individual though survived for 65.67 days gained maximum shell size (15.84 mm in length and body weight (419.87 mg. All individuals of April batch died prior to attainment of sexual maturity. In the remaining 11 batches the snails became sexually mature between 32 and 53 days. At this stage, they were with varying shell lengths, 9.3 mm to 13,11 mm in respect to batches. The reproduction period varied from 1-67 days. An individual laid, on an average, 0,25 (March batch to 443.67 (May batch eggs in its life-span. A batch of such snails would leave 24312, 22520, 720268, 80408, 76067, 418165, 214, 9202, 0, 0, 2459386 and 127894 individuals at the end of 352nd day. Since the environmental conditions were almost similar the 'dynamic' of population dynamics seems to be involved with the 'strain' of the snail individuals of the batches concerned.

An increase in insulin is important for the acquisition conditioned taste aversion in Lymnaea.

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Mita, Koichi; Yamagishi, Miki; Fujito, Yutaka; Lukowiak, Ken; Ito, Etsuro

2014-12-01

Conditioned taste aversion (CTA) in Lymnaea is brought about by pairing a sucrose solution (the conditioned stimulus, CS) with an electric shock (the unconditioned stimulus, US). Following repeated CS-US pairings, CTA occurs and it is consolidated into long-term memory (LTM). The best CTA is achieved, if snails are food-deprived for 1 day before training commences. With a longer period of food deprivation (5 days), learning and memory formation does not occur. It has been hypothesized that the levels of insulin in the central nervous system (CNS) are very important for CTA to occur. To test his hypothesis, we injected insulin directly into 5-day food-deprived snails. The injection of insulin, as expected, resulted in a decrease in hemolymph glucose concentration. Consistent with our hypothesis with insulin injection, learning and memory formation of CTA occurred. That is, the 'insulin spike' is more important than an increase in hemolymph glucose concentration for CTA-LTM. If we injected an insulin receptor antibody into the snails before the insulin injection, learning was formed but memory formation was not, which is consistent with our previous study. Therefore, a rise in the insulin concentration (i.e., insulin spike) in the CNS is considered to be a key determining factor in the process of CTA-LTM. Copyright © 2014 Elsevier Inc. All rights reserved.

Chemical composition and nutritional value of unripe banana flour (Musa acuminata, var. Nanicão).

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Menezes, Elizabete Wenzel; Tadini, Carmen Cecília; Tribess, Tatiana Beatris; Zuleta, Angela; Binaghi, Julieta; Pak, Nelly; Vera, Gloria; Dan, Milana Cara Tanasov; Bertolini, Andréa C; Cordenunsi, Beatriz Rosana; Lajolo, Franco M

2011-09-01

Banana flour obtained from unripe banana (Musa acuminata, var. Nanicão) under specific drying conditions was evaluated regarding its chemical composition and nutritional value. Results are expressed in dry weight (dw). The unripe banana flour (UBF) presented a high amount of total dietary fiber (DF) (56.24 g/100 g), which consisted of resistant starch (RS) (48.99 g/100 g), fructans (0.05 g/100 g) and DF without RS or fructans (7.2 g/100 g). The contents of available starch (AS) (27.78 g/100 g) and soluble sugars (1.81 g/100 g) were low. The main phytosterols found were campesterol (4.1 mg/100 g), stigmasterol (2.5 mg/100 g) and β-sitosterol (6.2 mg/100 g). The total polyphenol content was 50.65 mg GAE/100 g. Antioxidant activity, by the FRAP and ORAC methods, was moderated, being 358.67 and 261.00 μmol of Trolox equivalent/100 g, respectively. The content of Zn, Ca and Fe and mineral dialyzability were low. The procedure used to obtain UBF resulted in the recovery of undamaged starch granules and in a low-energy product (597 kJ/100 g).

Micropropagación de la planta medicinalPsychotria acuminata

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Alfonso Lara

2003-01-01

Full Text Available Psychotria acuminata es una planta medicinal que produce los alcaloides emetina, cephaelina y psychotrina, usados como expectorantes y eméticos. Hoy día estos alcaloides son extraídos de plantas silvestres pues esta especie no ha sido domesticada. Debido al uso potencial de los principios fitoquímicos, y a la escasa población de esta especie en el país, se desarrolló métodos de cultivo de tejidos para la reproducción clonal y masiva de esta planta. El material vegetal fue recolectado en 4 localidades de Costa Rica. En un medio de cultivo de Murashige y Skoog (MS, 1962, suplementado con 3 mg l-1 de BAP, 0,01 mg l-1 de ANA, 3% de azúcar y 2 g l-1 de phytagel, se logró la inducción de múltiples brotes a partir de las yemas axilares de microestacas (segmentos nodales de 1 cm de largo y de hojas provenientes de plántulas de 5 cm establecidas in vitro para 3 localidades. La formación de los brotes en las hojas ocurrió mediante organogénesis y embriogénesis. El enraizamiento in vitro de los brotes fue de un 100% cuando se utilizó un MS/2 suplementado con 6 mg l-1 de AIA. Debido a que el sistema radical generado in vitro muere una vez que las plántulas son sembradas en el sustrato en el invernadero, se utilizó Agriroot 1 DP® para generar raíces nuevas. Después de 8 semanas fue posible aclimatizar un 80% de las plántulas. La tasa de multiplicación, cuando se utiliza microestacas como explante, así como el tiempo para que ocurrieran los eventos morfogenéticos, fueron diferentes para los materiales de las 3 procedencias, lo que indica que las plantas de cada localidad son genéticamente diferentes.

Variações anatômicas em Lymnaea columella (Mollusca, Gastropoda

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Marlene T. Ueta

1977-12-01

Full Text Available Foram estudadas variações anatômicas de espécimes de L. columella coletados de diferentes criadouros situados em diversos Municípios do Estado de São Paulo: Campinas, Americana, Atibaia, Pirassununga, Caçapava e Taubaté. As comparações morfométricas foram baseadas em estudos do aparelho genital, rim e rádula. Foram medidos, para cada criadouro, os comprimentos do conjunto útero-vagina, dueto da espermateca, prepúcio e bainha do pênis. Foram ainda calculados os índices de relação entre bainha do pênis/prepúcio e estabelecidos os coeficientes de correlação entre comprimento da concha e comprimento do prepúcio. Cortes longitudiais do complexo peniano foram também objeto de estudo. Em relação a rádula foram determinados o número de fileiras transversais e o número de dentes por fileira, e estabelecida uma fórmula radular aproximada para os diversos criadouros.Soft parts of Lymnaea columella from ten populations from the State of São Paulo were studied in order to determine morphometric variations. These morphometric cornparisons were made upon reproductive system, kidney and radula of snail samples collected in different municipalities: Campinas, Americana, Atibaia, Pirassununga, Caçapava and Taubaté. Length measurementes of uterus, duct of spermatheca, prepuce and penis sheath were taken; the ratio penis sheath/prepuce and correlation coefficients between length of shell and length of prepuce were established. Longitudinal sections of penial complex were also studied. The number of trans verse rows, number of teeth per rows and the length of shell were determined. For each sample, the radular formula was indicated.

Genetic variation of Lymnaea stagnalis tolerance to copper: A test of selection hypotheses and its relevance for ecological risk assessment.

Science.gov (United States)

Côte, Jessica; Bouétard, Anthony; Pronost, Yannick; Besnard, Anne-Laure; Coke, Maïra; Piquet, Fabien; Caquet, Thierry; Coutellec, Marie-Agnès

2015-10-01

The use of standardized monospecific testing to assess the ecological risk of chemicals implicitly relies on the strong assumption that intraspecific variation in sensitivity is negligible or irrelevant in this context. In this study, we investigated genetic variation in copper sensitivity of the freshwater snail Lymnaea stagnalis, using lineages stemming from eight natural populations or strains found to be genetically differentiated at neutral markers. Copper-induced mortality varied widely among populations, as did the estimated daily death rate and time to 50% mortality (LT50). Population genetic divergence in copper sensitivity was compared to neutral differentiation using the QST-FST approach. No evidence for homogenizing selection could be detected. This result demonstrates that species-level extrapolations from single population studies are highly unreliable. The study provides a simple example of how evolutionary principles could be incorporated into ecotoxicity testing in order to refine ecological risk assessment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Relationship between the grades of a learned aversive-feeding response and the dopamine contents in Lymnaea

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Hitoshi Aonuma

2016-12-01

Full Text Available The pond snail Lymnaea learns conditioned taste aversion (CTA and remembers not to respond to food substances that initially cause a feeding response. The possible relationship between how well snails learn to follow taste-aversion training and brain dopamine contents is not known. We examined this relationship and found the following: first, snails in the act of eating just before the commencement of CTA training were poor learners and had the highest dopamine contents in the brain; second, snails which had an ad libitum access to food, but were not eating just before training, were average learners and had lower dopamine contents; third, snails food-deprived for one day before training were the best learners and had significantly lower contents of dopamine compared to the previous two cohorts. There was a negative correlation between the CTA grades and the brain dopamine contents in these three cohorts. Fourth, snails food-deprived for five days before training were poor learners and had higher dopamine contents. Thus, severe hunger increased the dopamine content in the brain. Because dopamine functions as a reward transmitter, CTA in the severely deprived snails (i.e. the fourth cohort was thought to be mitigated by a high dopamine content.

Actividad molusquicida del Paraiso (Melia azedarach L. (Meliaceae sobre Lymnaea cubensis, molusco vector de Fasciolosis

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Perez Marlene Piña

1998-01-01

Full Text Available INTRODUCCIÓN: La Fasciolosis constituye en diversas regiones una fuente importante de pérdidas económicas y cuando se descuidan las medidas de control de sus hospedadores (moluscos, junto a condiciones ecológicas favorables, pueden ocurrir casos aislados de Fasciolosis humana. Dentro de los métodos alternativos para su control está el uso de extractos vegetales y se pretendió evaluar el probable empleo del jugo extraído del fruto y semillas del Paraiso (Melia azedarach L. en el control de Lymnaea cubensis, principal vector de la Fasciolosis en Cuba. MATERIAL Y MÉTODO: Diferentes concentraciones del jugo extraído del fruto y semillas del Paraiso (Melia azedarach L. fueron testados para determinar las dosis letales media (DL50 y máxima (DL90 usando un programa computarizado Probit-Log. Siete series experimentales fueron probadas usando 72 moluscos en cada una. Para determinar la influencia sobre la frecuencia cardíaca fueron testados tres grupos de 10 moluscos, dos fueron tratados con las DL50=0,88627 y DL90=1,7641, respectivamente, mientras que el tercero fue considerado como testigo. RESULTADOS Y CONCLUSIONES: Se observó una marcada influencia de ambas dosis sobre la frecuencia cardíaca del molusco estudiado. Estos resultados son alentadores, pues demuestran el potencial empleo de esta planta en el control de moluscos indeseables.

Actividad molusquicida del Paraiso (Melia azedarach L. (Meliaceae sobre Lymnaea cubensis, molusco vector de Fasciolosis

Directory of Open Access Journals (Sweden)

Marlene Piña Perez

1998-06-01

Full Text Available INTRODUCCIÓN: La Fasciolosis constituye en diversas regiones una fuente importante de pérdidas económicas y cuando se descuidan las medidas de control de sus hospedadores (moluscos, junto a condiciones ecológicas favorables, pueden ocurrir casos aislados de Fasciolosis humana. Dentro de los métodos alternativos para su control está el uso de extractos vegetales y se pretendió evaluar el probable empleo del jugo extraído del fruto y semillas del Paraiso (Melia azedarach L. en el control de Lymnaea cubensis, principal vector de la Fasciolosis en Cuba. MATERIAL Y MÉTODO: Diferentes concentraciones del jugo extraído del fruto y semillas del Paraiso (Melia azedarach L. fueron testados para determinar las dosis letales media (DL50 y máxima (DL90 usando un programa computarizado Probit-Log. Siete series experimentales fueron probadas usando 72 moluscos en cada una. Para determinar la influencia sobre la frecuencia cardíaca fueron testados tres grupos de 10 moluscos, dos fueron tratados con las DL50=0,88627 y DL90=1,7641, respectivamente, mientras que el tercero fue considerado como testigo. RESULTADOS Y CONCLUSIONES: Se observó una marcada influencia de ambas dosis sobre la frecuencia cardíaca del molusco estudiado. Estos resultados son alentadores, pues demuestran el potencial empleo de esta planta en el control de moluscos indeseables.

Investigating apical adverse effects of four endocrine active substances in the freshwater gastropod Lymnaea stagnalis.

Science.gov (United States)

Giusti, Arnaud; Lagadic, Laurent; Barsi, Alpar; Thomé, Jean-Pierre; Joaquim-Justo, Célia; Ducrot, Virginie

2014-09-15

The hermaphroditic gastropod Lymnaea stagnalis is proposed as a candidate species for the development of OECD guidelines for testing of the reprotoxicity of chemicals, including endocrine active substances (EASs). Up to now, only a few putative EASs have been tested for their reproductive toxicity in this species. In this study, we investigate the effects of four EASs with different affinities to the vertebrate estrogen and androgen receptors (chlordecone as an estrogen; cyproterone acetate, fenitrothion and vinclozolin as anti-androgens) on the reproduction of L. stagnalis in a 21-day semi-static test. Testosterone and 17α-ethinylestradiol (EE2) were used as the reference compounds. The tested EASs had no significant effect on growth and survival at the tested concentration ranges (ng to μg/L). Classical reproduction endpoints (i.e., oviposition and fecundity) were not responsive to the tested chemicals, except for chlordecone and 17α-ethinylestradiol, which hampered reproduction from 19.6 μg/L and 17.6 μg/L, respectively. The frequency of polyembryonic eggs, used as an additional endpoint, demonstrated the effects of all compounds except EE2. The molecular pathways, which are involved in such reproduction impairments, remain unknown. Our results suggest that egg quality is a more sensitive endpoint as compared to other reproductive endpoints commonly assessed in mollusk toxicity tests. Copyright © 2014 Elsevier B.V. All rights reserved.

Post harvest changes of banana prata (Musa acuminata x Musa balbisiana group AAB) γ-irradiated

International Nuclear Information System (INIS)

Barros Villas Boas, Eduardo Valerio de.

1995-01-01

Pre-climateric bananas (Musa acuminata x Musa balbisiana [AAB group] cv. Prata) were stored without treatment (no radiation) or were exposed at 0.25 and 0.50 kGy of γ -irradiation, with a dose rate of 1 kGy.h -1 before storage. The fruits were analysed for CO 2 and ethylene production during maturation and pulp-to-peel ratio, starch, total soluble sugars, pectins, pectin methyl esterase and poly galacturonase activities on 6 colour score of peel. The radiation dose/peel-colour interaction affected the pulp-to-peel ratio significantly, while the fruits subjected at 0.25 Gy had the highest increase on the colour scores 5, 6, and 7. A predictable increase in the conversion of starch to sugar took place during maturation and a delaying on the soluble sugar accumulation was noted on the fruits submitted to 0.50 kGy, in the 6 and 7 colour scores only. A decrease on the total pectin content and a trend of a higher solubilization of pectins was observed in the fruits γ-irradiated at 0.50 kGy. Higher pectin methyl esterase activities were exhibited by irradiated fruits, although the γ-irradiation has suppressed the poly galacturonase activity throughout the maturation period. (author). 110 refs., 11 figs., 5 tabs

Metabolomics to Explore Imidacloprid-Induced Toxicity in the Central Nervous System of the Freshwater Snail Lymnaea stagnalis.

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Tufi, Sara; Stel, Jente M; de Boer, Jacob; Lamoree, Marja H; Leonards, Pim E G

2015-12-15

Modern toxicology is seeking new testing methods to better understand toxicological effects. One of the most concerning chemicals is the neonicotinoid pesticide imidacloprid. Although imidacloprid is designed to target insects, recent studies have shown adverse effects on nontarget species. Metabolomics was applied to investigate imidacloprid-induced sublethal toxicity in the central nervous system of the freshwater snail Lymnaea stagnalis. The snails (n = 10 snails) were exposed for 10 days to increasing imidacloprid concentrations (0.1, 1, 10, and 100 μg/L). The comparison between control and exposure groups highlighted the involvement and perturbation of many biological pathways. The levels of several metabolites belonging to different metabolite classes were significantly changed by imidacloprid exposure. A change in the amino acids and nucleotide metabolites like tryptophan, proline, phenylalanine, uridine, and guanosine was found. Many fatty acids were down-regulated, and the levels of the polyamines, spermidine and putrescine, were found to be increased which is an indication of neuron cell injury. A turnover increase between choline and acetylcholine led us to hypothesize an increase in cholinergic gene expression to overcome imidacloprid binding to the nicotinic acetylcholine receptors. Metabolomics revealed imidacloprid induced metabolic changes at low and environmentally relevant concentration in a nontarget species and generated a novel mechanistic hypothesis.

Modelling effects of diquat under realistic exposure patterns in genetically differentiated populations of the gastropod Lymnaea stagnalis.

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Ducrot, Virginie; Péry, Alexandre R R; Lagadic, Laurent

2010-11-12

Pesticide use leads to complex exposure and response patterns in non-target aquatic species, so that the analysis of data from standard toxicity tests may result in unrealistic risk forecasts. Developing models that are able to capture such complexity from toxicity test data is thus a crucial issue for pesticide risk assessment. In this study, freshwater snails from two genetically differentiated populations of Lymnaea stagnalis were exposed to repeated acute applications of environmentally realistic concentrations of the herbicide diquat, from the embryo to the adult stage. Hatching rate, embryonic development duration, juvenile mortality, feeding rate and age at first spawning were investigated during both exposure and recovery periods. Effects of diquat on mortality were analysed using a threshold hazard model accounting for time-varying herbicide concentrations. All endpoints were significantly impaired at diquat environmental concentrations in both populations. Snail evolutionary history had no significant impact on their sensitivity and responsiveness to diquat, whereas food acted as a modulating factor of toxicant-induced mortality. The time course of effects was adequately described by the model, which thus appears suitable to analyse long-term effects of complex exposure patterns based upon full life cycle experiment data. Obtained model outputs (e.g. no-effect concentrations) could be directly used for chemical risk assessment.

Inhibition of acetylcholinesterase and cytochrome oxidase activity in Fasciola gigantica cercaria by phytoconstituents.

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Sunita, Kumari; Habib, Maria; Kumar, P; Singh, Vinay Kumar; Husain, Syed Akhtar; Singh, D K

2016-02-01

Fasciolosis is an important cattle and human disease caused by Fasciola hepatica and Fasciola gigantica. One of the possible methods to control this problem is to interrupt the life cycle of Fasciola by killing its larva (redia and cercaria) in host snail. Molecular identification of cercaria larva of F. gigantica was done by comparing the nucleotide sequencing with adult F. gigantica. It was noted that nucleotide sequencing of cercaria larva and adult F. gigantica were 99% same. Every month during the year 2011-2012, in vivo treatment with 60% of 4 h LC50 of phyto cercaricides citral, ferulic acid, umbelliferone, azadirachtin and allicin caused significant inhibition of acetylcholinesterase (AChE) and cytochrome oxidase activity in the treated cercaria larva of F. gigantica. Whereas, activity of both enzymes were not significantly altered in the nervous tissues of vector snail Lymnaea acuminata exposed to same treatments. Maximum reduction in AChE (1.35% of control in month of June) and cytochrome oxidase (3.71% of control in the month of July) activity were noted in the cercaria exposed to 60% of 4 h LC50 of azadirachtin and allicin, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

Fascioliasis Control: In Vivo and In Vitro Phytotherapy of Vector Snail to Kill Fasciola Larva

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Kumari Sunita

2011-01-01

Full Text Available Snail is one of the important components of an aquatic ecosystem, it acts as intermediate host of Fasciola species. Control of snail population below a certain threshold level is one of the important methods in the campaign to reduce the incidence of fascioliasis. Life cycle of the parasite can be interrupted by killing the snail or Fasciola larva redia and cercaria in the snail body. In vivo and in vitro toxicity of the plant products and their active component such as citral, ferulic acid, umbelliferone, azadirachtin, and allicin against larva of Fasciola in infected snail Lymnaea acuminata were tested. Mortality of larvae were observed at 2 h, 4 h, 6 h, and 8 h, of treatment. In in vivo treatment, azadirachtin caused highest mortality in redia and cercaria larva (8 h, LC50 0.11, and 0.05 mg/L whereas in in vitro condition allicin was highly toxic against redia and cercaria (8 h, LC50 0.01, and 0.009 mg/L. Toxicity of citral was lowest against redia and cercaria larva.

Reproductive impacts of tributyltin (TBT) and triphenyltin (TPT) in the hermaphroditic freshwater gastropod Lymnaea stagnalis.

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Giusti, Arnaud; Barsi, Alpar; Dugué, Maël; Collinet, Marc; Thomé, Jean-Pierre; Joaquim-Justo, Célia; Roig, Benoit; Lagadic, Laurent; Ducrot, Virginie

2013-07-01

Tributyltin (TBT) and triphenyltin (TPT) are emblematic endocrine disruptors, which have been mostly studied in gonochoric prosobranchs. Although both compounds can simultaneously occur in the environment, they have mainly been tested separately for their effects on snail reproduction. Because large discrepancies in experimental conditions occurred in these tests, the present study aimed to compare the relative toxicity of TBT and TPT under similar laboratory conditions in the range of 0 ng Sn/L to 600 ng Sn/L. Tests were performed on the simultaneous hermaphrodite Lymnaea stagnalis, a freshwater snail in which effects of TPT were unknown. Survival, shell length, and reproduction were monitored in a 21-d semistatic test. Frequency of abnormal eggs was assessed as an additional endpoint. Triphenyltin hampered survival while TBT did not. Major effects on shell solidity and reproduction were observed for both compounds, reproductive outputs being more severely hampered by TBT than by TPT. Considering the frequency of abnormal eggs allowed increasing test sensitivity, because snail responses to TBT could be detected at concentrations as low as 19 ng Sn/L. However, the putative mode of action of the 2 compounds could not be deduced from the structure of the molecules or from the response of apical endpoints. Sensitivity of L. stagnalis to TBT and TPT was compared with the sensitivity of prosobranch mollusks with different habitats and different reproductive strategies. Copyright © 2013 SETAC.

DNA multigene characterization of Fasciola hepatica and Lymnaea neotropica and its fascioliasis transmission capacity in Uruguay, with historical correlation, human report review and infection risk analysis

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Gayo, Valeria; Sanchis, Jaime; Artigas, Patricio; Khoubbane, Messaoud; Birriel, Soledad; Mas-Coma, Santiago

2017-01-01

Background Fascioliasis is a pathogenic disease transmitted by lymnaeid snails and recently emerging in humans, in part due to effects of climate changes, anthropogenic environment modifications, import/export and movements of livestock. South America is the continent presenting more human fascioliasis hyperendemic areas and the highest prevalences and intensities known. These scenarios appear mainly linked to altitude areas in Andean countries, whereas lowland areas of non-Andean countries, such as Uruguay, only show sporadic human cases or outbreaks. A study including DNA marker sequencing of fasciolids and lymnaeids, an experimental study of the life cycle in Uruguay, and a review of human fascioliasis in Uruguay, are performed. Methodology/Principal findings The characterization of Fasciola hepatica from cattle and horses of Uruguay included the complete sequences of the ribosomal DNA ITS-2 and ITS-1 and mitochondrial DNA cox1 and nad1. ITS-2, ITS-1, partial cox1 and rDNA 16S gene of mtDNA were used for lymnaeids. Results indicated that vectors belong to Lymnaea neotropica instead of to Lymnaea viator, as always reported from Uruguay. The life cycle and transmission features of F. hepatica by L. neotropica of Uruguay were studied under standardized experimental conditions to enable a comparison with the transmission capacity of F. hepatica by Galba truncatula at very high altitude in Bolivia. On this baseline, we reviewed the 95 human fascioliasis cases reported in Uruguay and analyzed the risk of human infection in front of future climate change estimations. Conclusions/Significance The correlation of fasciolid and lymnaeid haplotypes with historical data on the introduction and spread of livestock into Uruguay allowed to understand the molecular diversity detected. Although Uruguayan L. neotropica is a highly efficient vector, its transmission capacity is markedly lower than that of Bolivian G. truncatula. This allows to understand the transmission and

DNA multigene characterization of Fasciola hepatica and Lymnaea neotropica and its fascioliasis transmission capacity in Uruguay, with historical correlation, human report review and infection risk analysis.

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Bargues, María Dolores; Gayo, Valeria; Sanchis, Jaime; Artigas, Patricio; Khoubbane, Messaoud; Birriel, Soledad; Mas-Coma, Santiago

2017-02-01

Fascioliasis is a pathogenic disease transmitted by lymnaeid snails and recently emerging in humans, in part due to effects of climate changes, anthropogenic environment modifications, import/export and movements of livestock. South America is the continent presenting more human fascioliasis hyperendemic areas and the highest prevalences and intensities known. These scenarios appear mainly linked to altitude areas in Andean countries, whereas lowland areas of non-Andean countries, such as Uruguay, only show sporadic human cases or outbreaks. A study including DNA marker sequencing of fasciolids and lymnaeids, an experimental study of the life cycle in Uruguay, and a review of human fascioliasis in Uruguay, are performed. The characterization of Fasciola hepatica from cattle and horses of Uruguay included the complete sequences of the ribosomal DNA ITS-2 and ITS-1 and mitochondrial DNA cox1 and nad1. ITS-2, ITS-1, partial cox1 and rDNA 16S gene of mtDNA were used for lymnaeids. Results indicated that vectors belong to Lymnaea neotropica instead of to Lymnaea viator, as always reported from Uruguay. The life cycle and transmission features of F. hepatica by L. neotropica of Uruguay were studied under standardized experimental conditions to enable a comparison with the transmission capacity of F. hepatica by Galba truncatula at very high altitude in Bolivia. On this baseline, we reviewed the 95 human fascioliasis cases reported in Uruguay and analyzed the risk of human infection in front of future climate change estimations. The correlation of fasciolid and lymnaeid haplotypes with historical data on the introduction and spread of livestock into Uruguay allowed to understand the molecular diversity detected. Although Uruguayan L. neotropica is a highly efficient vector, its transmission capacity is markedly lower than that of Bolivian G. truncatula. This allows to understand the transmission and epidemiological differences between Andean highlands and non

Accumulation of free and covalently bound microcystins in tissues of Lymnaea stagnalis (Gastropoda) following toxic cyanobacteria or dissolved microcystin-LR exposure.

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Lance, Emilie; Neffling, Milla-Riina; Gérard, Claudia; Meriluoto, Jussi; Bormans, Myriam

2010-03-01

Accumulation of free microcystins (MCs) in freshwater gastropods has been demonstrated but accumulation of MCs covalently bound to tissues has never been considered so far. Here, we follow the accumulation of total (free and bound) MCs in Lymnaea stagnalis exposed to i) dissolved MC-LR (33 and 100 microg L(-1)) and ii) Planktothrix agardhii suspensions producing 5 and 33 microg MC-LR equivalents L(-1) over a 5-week period, and after a 3-week depuration period. Snails exposed to dissolved MC-LR accumulated up to 0.26 microg total MCs g(-1) dry weight (DW), with no detection of bound MCs. Snails exposed to MCs producing P. agardhii accumulated up to 69.9 microg total MCs g(-1) DW, of which from 17.7 to 66.7% were bound. After depuration, up to 15.3 microg g(-1) DW of bound MCs were detected in snails previously exposed to toxic cyanobacteria, representing a potential source of MCs transfer through the food web. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

Aspects of the Maintenance of the Life Cycle of Fasciola hepatica in Lymnaea columella in Minas Gerais, Brazil

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Souza Cecília Pereira de

2002-01-01

Full Text Available Fascioliasis is a parasitic disease of domestic ruminants that occurs worldwide. The lymnaeid intermediate hosts of Fasciola hepatica include Lymnaea columella, which is widely distributed in Brazil. A colony of L. columella from Belo Horizonte, MG, was reared in our laboratory to be used in studies of the F. hepatica life cycle, the intermediate host-parasite relationship and development of an anti-helminthic vaccine. In the first experiment 1,180 snails were exposed to miracidia of F. hepatica eggs removed from the biliary tracts of cattle from the State of Rio Grande do Sul. In the second and third experiments the snails were exposed to miracidia that had emerged from F. hepatica eggs from Uruguay, maintained in rabbits. The rates of infection in the first, second and third experiments were 0, 42.1 and 0% respectively. Over 15,806 metacercariae were obtained and stored at 4ºC. Four rabbits weighing 1.5 kg each were infected with 32-44 metacercariae and two with 200. Three rabbits begin to eliminate eggs of the parasite in the feces from 84 days after infection onwards. The biological cycle of F. hepatica in L. columella and the rabbit was completed within 124 days.

Metallothionein and glutathione in Lymnaea stagnalis determine the specificity of responses to the effects of ionising radiation

International Nuclear Information System (INIS)

Gnatyshyna, L.; Falfushynska, H.; Stoliar, O.; Bodilovska, O.; Oleynik, O.; Golubev, A.

2012-01-01

The aim of our study was to distinguish the stress-related molecular response of the pulmonate mollusc Lymnaea stagnalis from the Chernobyl area in comparison with the consequences of other harmful effects, including the short-term effects of radiation and heating. Specimens inhabiting ponds near the Chernobyl nuclear power plant, the cooling channel of the electric power station and the soil reclamation channel (groups R, T and C, correspondingly), and specimens adapted to laboratory conditions (a control group (CL), a disposable group exposed to 2 mGy X-ray radiation over the body (RL), and a group exposed to 25 deg. C for 4 days (TL)) were compared. Despite high variability of responses, Principle Component Analysis distinctly separated the laboratory and feral groups into two sets. In the feral groups, low levels of the stress-related and metal-binding protein metallothionein (MT), protein carbonyls and lactate dehydrogenase in the digestive gland were indicated. The main separating criteria selected by classification and regression tree analysis were the protein carbonyls, cholinesterase and MT. Molluscs from group R were clearly distinguished by the lowest levels of MT, Mn-superoxide dismutase and lactate dehydrogenase, and the highest level of glutathione, demonstrating that the oppression of the gene-determined stress-related response and its partially metabolic compensation can be possible markers for chronic environmental effects of irradiation. (authors)

Calcification in the staghorn coral Acropora acuminata: variations in apparent skeletal incorporation of radioisotopes due to different methods of processing

International Nuclear Information System (INIS)

Crossland, C.J.; Barnes, D.J.

1977-01-01

Pieces of branch from the staghorn coral Acropora acuminata were incubated with 45 CaCl 2 and NaH 14 CO 3 under identical conditions in the light or in the dark. Specimens were then processed in different ways. All specimens were placed in N KOH to digest tissues. Some were placed in KOH immediately after incubation; others were placed in KOH after 2 h washing, or after 2 h extraction with methanol-chloroform-water. Specimens were washed in running fresh water or running seawater; some were killed in liquid N 2 before washing. Radioactivity associated with skeleton and tissues was determined. The method of processing profoundly affected the results. In dark incubations, there was up to a four-fold difference in apparent skeletal incorporation of 45 Ca ++ between average values obtained for the different treatments. For 14 C incorporation, there was a difference of up to 2.5 times. In light incubations, skeletal incorporation of both radioisotopes showed a two-fold difference between high and low average values obtained for the different treatments. (orig.) [de

Does water chemistry affect the dietary uptake and toxicity of silver nanoparticles by the freshwater snail Lymnaea stagnalis?

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López-Serrano Oliver, Ana; Croteau, Marie-Noële; Stoiber, Tasha L.; Tejamaya, Mila; Römer, Isabella; Lead, Jamie R.; Luoma, Samuel N.

2014-01-01

Silver nanoparticles (AgNPs) are widely used in many applications and likely released into the aquatic environment. There is increasing evidence that Ag is efficiently delivered to aquatic organisms from AgNPs after aqueous and dietary exposures. Accumulation of AgNPs through the diet can damage digestion and adversely affect growth. It is well recognized that aspects of water quality, such as hardness, affect the bioavailability and toxicity of waterborne Ag. However, the influence of water chemistry on the bioavailability and toxicity of dietborne AgNPs to aquatic invertebrates is largely unknown. Here we characterize for the first time the effects of water hardness and humic acids on the bioaccumulation and toxicity of AgNPs coated with polyvinyl pyrrolidone (PVP) to the freshwater snail Lymnaea stagnalis after dietary exposures. Our results indicate that bioaccumulation and toxicity of Ag from PVP-AgNPs ingested with food are not affected by water hardness and by humic acids, although both could affect interactions with the biological membrane and trigger nanoparticle transformations. Snails efficiently assimilated Ag from the PVP-AgNPs mixed with diatoms (Ag assimilation efficiencies ranged from 82 to 93%). Rate constants of Ag uptake from food were similar across the entire range of water hardness and humic acid concentrations. These results suggest that correcting regulations for water quality could be irrelevant and ineffective where dietary exposure is important.

Natural infection of trematodes in Lymnaea (Radix) auricularia rubiginosa in water reservoirs in Amphoe Muang, Khon Kaen Province.

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Charoenchai, A; Tesana, S; Pholpark, M

1997-01-01

Lymnaea (Radix) auricularia rubiginosa (Michelin, 1831) was surveyed in 54 reservoirs of 18 districts in Amphoe Muang, Khon Kaen Province during February to May 1994. Lymnaeid snails were found in the water of 20 reservoirs, of which 16 reservoirs contained clear water and 4 turbid water. Two of the four turbid water reservoirs received drainage water from Khon Kaen Town. Two thousand four hundred and eight L. auricularia rubiginosa were collected and examined by shedding and crushing. Trematode infection occurred in 163 (6.77%) of 2,408 L. auricularia rubiginosa and some snails were infected with more than one cercarial species. Ninety-nine snails (4.11%) were infected with echinostomes, while mixed infection of echinostomes with Fasciola gigantica and with schistosomes was found in 5 snails (0.21%) and 2 snails (0.08%), respectively. Only 1 snail (0.04%), 19 snails (0.79%) and 37 snails (1.54%) were infected with F. gigantica, schistosomes and unidentified species, respectively. The mean size of infected snails was 6.89 +/- 2.02 mm (6.20-22.36) while the mean of sampled snails was 13.46 +/- 3.64 mm (4.00-26.55). The water plants which were found in reservoirs and presented with snails, were creeping water primose (Jusstaea repens), water lily (Nymphaea sp), water hyacinths (Eichornia crassipes) and grass.

Training Lymnaea in the presence of a predator scent results in a long-lasting ability to form enhanced long-term memory.

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Forest, Jeremy; Sunada, Hiroshi; Dodd, Shawn; Lukowiak, Ken

2016-06-01

Lymnaea exposed to crayfish effluent (CE) gain an enhanced ability to form long-term memory (LTM). We test the hypothesis that a single CE exposure and operant conditioning training leads to long lasting changes in the capability of snails to form LTM when tested in pond water four weeks later. We trained both juvenile and adult snails with a single 0.5 h training session in CE and show that LTM was present 24 h later. Snails trained in a similar manner in just pond water show no LTM. We then asked if such training in CE conferred enhanced memory forming capabilities on these snails four weeks later. That is, would LTM be formed in these snails four weeks later following a single 0.5 h training session in pond water? We found that both adult and juvenile snails previously trained in CE one month previously had enhanced LTM formation abilities. The injection of a DNA methylation blocker, 5-AZA, prior to training in adult snails blocked enhanced LTM formation four weeks later. Finally, this enhanced LTM forming ability was not passed on to the next generation of snails.

Accumulation of free and covalently bound microcystins in tissues of Lymnaea stagnalis (Gastropoda) following toxic cyanobacteria or dissolved microcystin-LR exposure

International Nuclear Information System (INIS)

Lance, Emilie; Neffling, Milla-Riina; Gerard, Claudia; Meriluoto, Jussi; Bormans, Myriam

2010-01-01

Accumulation of free microcystins (MCs) in freshwater gastropods has been demonstrated but accumulation of MCs covalently bound to tissues has never been considered so far. Here, we follow the accumulation of total (free and bound) MCs in Lymnaea stagnalis exposed to i) dissolved MC-LR (33 and 100 μg L -1 ) and ii) Planktothrix agardhii suspensions producing 5 and 33 μg MC-LR equivalents L -1 over a 5-week period, and after a 3-week depuration period. Snails exposed to dissolved MC-LR accumulated up to 0.26 μg total MCs g -1 dry weight (DW), with no detection of bound MCs. Snails exposed to MCs producing P. agardhii accumulated up to 69.9 μg total MCs g -1 DW, of which from 17.7 to 66.7% were bound. After depuration, up to 15.3 μg g -1 DW of bound MCs were detected in snails previously exposed to toxic cyanobacteria, representing a potential source of MCs transfer through the food web. - The study concerns accumulation and elimination of both free and bound microcystins (MCs) in tissues of a gastropod exposed to MCs producing cyanobacteria or dissolved MC-LR.

Accumulation of free and covalently bound microcystins in tissues of Lymnaea stagnalis (Gastropoda) following toxic cyanobacteria or dissolved microcystin-LR exposure

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Lance, Emilie, E-mail: emilie.lance@live.f [UMR CNRS Ecobio 6553, University of Rennes 1, Campus de Beaulieu, 265 Avenue du General Leclerc, 35042 Rennes Cedex (France); Neffling, Milla-Riina [Department of Biochemistry and Pharmacy, Abo Akademi University, Tykistoekatu 6, FI-20520 Turku (Finland); Gerard, Claudia [UMR CNRS Ecobio 6553, University of Rennes 1, Campus de Beaulieu, 265 Avenue du General Leclerc, 35042 Rennes Cedex (France); Meriluoto, Jussi [Department of Biochemistry and Pharmacy, Abo Akademi University, Tykistoekatu 6, FI-20520 Turku (Finland); Bormans, Myriam [UMR CNRS Ecobio 6553, University of Rennes 1, Campus de Beaulieu, 265 Avenue du General Leclerc, 35042 Rennes Cedex (France)

2010-03-15

Accumulation of free microcystins (MCs) in freshwater gastropods has been demonstrated but accumulation of MCs covalently bound to tissues has never been considered so far. Here, we follow the accumulation of total (free and bound) MCs in Lymnaea stagnalis exposed to i) dissolved MC-LR (33 and 100 mug L{sup -1}) and ii) Planktothrix agardhii suspensions producing 5 and 33 mug MC-LR equivalents L{sup -1} over a 5-week period, and after a 3-week depuration period. Snails exposed to dissolved MC-LR accumulated up to 0.26 mug total MCs g{sup -1} dry weight (DW), with no detection of bound MCs. Snails exposed to MCs producing P. agardhii accumulated up to 69.9 mug total MCs g{sup -1} DW, of which from 17.7 to 66.7% were bound. After depuration, up to 15.3 mug g{sup -1} DW of bound MCs were detected in snails previously exposed to toxic cyanobacteria, representing a potential source of MCs transfer through the food web. - The study concerns accumulation and elimination of both free and bound microcystins (MCs) in tissues of a gastropod exposed to MCs producing cyanobacteria or dissolved MC-LR.

Identification of pectenotoxins in plankton, filter feeders, and isolated cells of a Dinophysis acuminata with an atypical toxin profile, from Chile.

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Blanco, Juan; Alvarez, Gonzalo; Uribe, Eduardo

2007-04-01

A bloom of Dinophysis acuminata produced, in autumn of 2005, a closure of the scallop harvesting in Bahía Inglesa, in the Chilean III region. Isolated cells of this Dinophysis species were shown to contain 180 pg cell(-1) of pectenotoxin 2 but neither okadaic acid nor any of its analogs or derivatives (at least at a detectable level). Examination of plankton and filter-feeder samples covering an area of ca. 350 km, from the location where the toxicity was recorded to Bahía Tongoy, showed that the unique toxin profile found in the first bloom was widespread over that part of Chile and persisted for months. The analysis were carried out by HPLC-ESI-MS using positive ionization mode, with a detection limit below 2 ng of OA mL(-1) of methanolic extract. This is the first report of the presence of pectenotoxins in the plankton of the Pacific coast of America and in the studied filter feeders. This is also the first report of a Dinophysis species containing pectenotoxins and not any toxin of the okadaic acid group.

One-trial conditioned taste aversion in Lymnaea: good and poor performers in long-term memory acquisition.

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Sugai, Rio; Azami, Sachiyo; Shiga, Hatsuki; Watanabe, Takayuki; Sadamoto, Hisayo; Kobayashi, Suguru; Hatakeyama, Dai; Fujito, Yutaka; Lukowiak, Ken; Ito, Etsuro

2007-04-01

In the majority of studies designed to elucidate the causal mechanisms of memory formation, certain members of the experimental cohort, even though subjected to exactly the same conditioning procedures, remember significantly better than others, whereas others show little or no long-term memory (LTM) formation. To begin to address the question of why this phenomenon occurs and thereby help clarify the causal mechanism of LTM formation, we used a conditioned taste aversion (CTA) procedure on individuals of the pond snail Lymnaea stagnalis and analyzed their subsequent behavior. Using sucrose as an appetitive stimulus and KCl as an aversive stimulus, we obtained a constant ratio of ;poor' to ;good' performers for CTA-LTM. We found that approximately 40% of trained snails possessed LTM following a one-trial conditioning procedure. When we examined the time-window necessary for the memory consolidation, we found that if we cooled snails to 4 degrees C for 30 min within 10 min after the one-trial conditioning, LTM was blocked. However, with delayed cooling (i.e. longer than 10 min), LTM was present. We could further interfere with LTM formation by inducing inhibitory learning (i.e. backward conditioning) after the one-trial conditioning. Finally, we examined whether we could motivate snails to acquire LTM by depriving them of food for 5 days before the one-trial conditioning. Food-deprived snails, however, failed to exhibit LTM following the one-trial conditioning. These results will help us begin to clarify why some individuals are better at learning and forming memory for specific tasks at the neuronal level.

Evaluation of physico-chemical and antioxidant properties in different varieties of banana (musa acuminata), indigenous to pakistan

International Nuclear Information System (INIS)

Azizuddin, A.; Ghafoor, S.; Mahmood, T.

2014-01-01

The antioxidant capacity, phenolic and flavonoid contents, and physico-chemical analysis on the pulp of three different varieties of Musa acuminata, were studied namely Cavendish basrai, Grand naine and Plantain, collected from Gharo, Adam Khas Kheli Road near Karachi (Pakistan). DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging, reducing power (RPA) and phosphomolybdenum assays were used for determination of their antioxidant capacity. Cavendish basrai characterized the highest antioxidant capacity among three varieties, DPPH (82.46 % inhibition at 0.1 mM conc.), RPA (43.59 mg/100 g) and phosphomolybdenum (38.90 mg/100 g) in methanolic extract and DPPH (67.27 % inhibition at 0.1 mM conc.), RPA (27.03 mg/100 g) and phosphomolybdenum (24.27 mg/100 g) in water extract. The phenolic (83.04 mg/100 g, 19.50 mg/100 g) and flavonoid contents (11.66 mg/100 g, 4.77 mg/100 g) were also high in Cavendish basrai in methanolic and water extracts, respectively showed the direct relation of antioxidant capacity to the phenolic and flavonoid contents, and the DPPH assay revealed more power full assay for determination of antioxidant capacity among these assays. In correlation with antioxidant capacity, Plantain showed comparatively high physico-chemical characteristics revealed high nutritional contents such as total dry matter, total sugar contents, TSS, titratable acidity and % NaCl. (author)

DNA sequence characterisation and phylogeography of Lymnaea cousini and related species, vectors of fascioliasis in northern Andean countries, with description of L. meridensis n. sp. (Gastropoda: Lymnaeidae

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Bargues M Dolores

2011-07-01

Full Text Available Abstract Background Livestock fascioliasis is a problem throughout Ecuador, Colombia and Venezuela, mainly in Andean areas where the disease also appears to affect humans. Transmission patterns and epidemiological scenarios of liver fluke infection have shown to differ according to the lymnaeid vector snail species involved. These Andean countries present the vectors Lymnaea cousini, L. bogotensis and L. ubaquensis, unknown in the rest of Latin America. An exhaustive combined haplotype study of these species is performed by means of DNA sequencing of the nuclear ribosomal 18S RNA gene, ITS-2 and ITS-1, and mitochondrial DNA cox1 gene. Results The conserved 5.8S rDNA sequence corroborated that no pseudogenes are involved in the numerous non-microsatellite/minisatellite-related indels appearing between the ITS-2 and ITS-1 sequences when comparing different L. cousini - L. bogotensis populations. Sequence analyses and phylogenetic reconstruction methods including other lymnaeid vector species show that (i L. bogotensis is a synonym of L. cousini, (ii L. ubaquensis is a synonym of Pseudosuccinea columella, and (iii populations of L. cousini hitherto known from Venezuelan highlands indeed belong to a new species for which the name L. meridensis n. sp. is proposed. This new species is described and a complete phenotypic differentiation provided. Conclusions ITS-2, ITS-1 and cox1 prove to be good markers for specimen classification and haplotype characterisation of these morphologically similar lymnaeids in endemic areas. Analysis of the 18S gene and phylogenetic reconstructions indicate that L. cousini and L. meridensis n. sp. cluster in an evolutionary line different from the one of P. columella, despite their external resemblance. This suggests an evolutionary phenotypic convergence related to similar environments and which has given rise to frequent specimen misclassification. Body size and phylogenetic relationships of L. meridensis n. sp. with

DNA sequence characterisation and phylogeography of Lymnaea cousini and related species, vectors of fascioliasis in northern Andean countries, with description of L. meridensis n. sp. (Gastropoda: Lymnaeidae)

Science.gov (United States)

2011-01-01

Background Livestock fascioliasis is a problem throughout Ecuador, Colombia and Venezuela, mainly in Andean areas where the disease also appears to affect humans. Transmission patterns and epidemiological scenarios of liver fluke infection have shown to differ according to the lymnaeid vector snail species involved. These Andean countries present the vectors Lymnaea cousini, L. bogotensis and L. ubaquensis, unknown in the rest of Latin America. An exhaustive combined haplotype study of these species is performed by means of DNA sequencing of the nuclear ribosomal 18S RNA gene, ITS-2 and ITS-1, and mitochondrial DNA cox1 gene. Results The conserved 5.8S rDNA sequence corroborated that no pseudogenes are involved in the numerous non-microsatellite/minisatellite-related indels appearing between the ITS-2 and ITS-1 sequences when comparing different L. cousini - L. bogotensis populations. Sequence analyses and phylogenetic reconstruction methods including other lymnaeid vector species show that (i) L. bogotensis is a synonym of L. cousini, (ii) L. ubaquensis is a synonym of Pseudosuccinea columella, and (iii) populations of L. cousini hitherto known from Venezuelan highlands indeed belong to a new species for which the name L. meridensis n. sp. is proposed. This new species is described and a complete phenotypic differentiation provided. Conclusions ITS-2, ITS-1 and cox1 prove to be good markers for specimen classification and haplotype characterisation of these morphologically similar lymnaeids in endemic areas. Analysis of the 18S gene and phylogenetic reconstructions indicate that L. cousini and L. meridensis n. sp. cluster in an evolutionary line different from the one of P. columella, despite their external resemblance. This suggests an evolutionary phenotypic convergence related to similar environments and which has given rise to frequent specimen misclassification. Body size and phylogenetic relationships of L. meridensis n. sp. with well-known vectors as

Consolidation of long-term memory by insulin in Lymnaea is not brought about by changing the number of insulin receptors.

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Hatakeyama, Dai; Okuta, Akiko; Otsuka, Emi; Lukowiak, Ken; Ito, Etsuro

2013-05-01

The pond snail Lymnaea stagnalis learns taste aversion and consolidates it into long-term memory (LTM). This is referred to as conditioned taste aversion (CTA). The superfusion of molluscan insulin-related peptides (MIPs) over the isolated snail brain causes a long-term enhancement of synaptic input between the cerebral giant cell and the B1 buccal motor neuron. This enhancement is hypothesized to underlie CTA. The synaptic enhancement caused by the superfusion of MIPs can be blocked by the application of human insulin receptor antibody, which recognizes the extracellular domain of human insulin receptor and acts as an antagonist even for MIP receptors. An injection of the human insulin receptor antibody into the abdominal cavity of trained snails blocks the consolidation process leading to LTM, even though the snails acquire taste aversion. Here, we examined whether or not taste-aversion training changes the mRNA expression level of MIP receptor in the snail brain and found that it does not. This result, taken together with previous findings, suggest that the MIPs' effect on synaptic function in the snail brain is attributable to a change in the MIP concentration, and not to a change in the mRNA expression level of MIP receptor, which is thought to reflect the number of MIP receptors.

Construction and characterization of a plant transformation-competent BIBAC library of the black Sigatoka-resistant banana Musa acuminata cv. Tuu Gia (AA).

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Ortiz-Vázquez, E; Kaemmer, D; Zhang, H-B; Muth, J; Rodríguez-Mendiola, M; Arias-Castro, C; James, Andrew

2005-02-01

A plant transformation-competent binary bacterial artificial chromosome (BIBAC) library was constructed from Musa acuminata cv. Tuu Gia (AA), a black Sigatoka-resistant diploid banana. After digestion of high-molecular-weight banana DNA by HindIII, several methods of DNA size selection were tested, followed by ligation, using a vector/insert molar ratio of 4:1. The library consists of 30,700 clones stored in 80 384-well microtiter plates. The mean insert size was estimated to be 100 kb, and the frequency of inserts with internal NotI sites was 61%. The majority of insert sizes fell into the range of 100+/-20 kb, making them suitable for Agrobacterium-mediated transformation. Only 1% and 0.9% of the clones contain chloroplast and mitochondrial DNA, respectively. This is the first BIBAC library for banana, estimated to represent five times its haploid genome (600 Mbp). It was demonstrated by hybridization that the library contains typical members of resistance gene and defense gene families that can be used for transformation of disease susceptible banana cultivars for banana genetic improvement.

Bioaccumulation and toxic effects of cadmium on feeding and growth of an Indian pond snail Lymnaea luteola L. under laboratory conditions

International Nuclear Information System (INIS)

Das, Sangita; Khangarot, B.S.

2010-01-01

Effects of dissolved cadmium exposure on the survival, feeding, growth rates and accumulation in Indian pond snails Lymnaea luteola L. were examined for a period of 7 weeks. The concentrations of cadmium tested were 0, 10, 32, 100, 320, 560, and 1000 μg l -1 . Cadmium exposure significantly inhibited the feeding and growth rates. At higher Cd concentrations snails refused to consume food offered as plant Marsilia sp. leaves. Cadmium mainly accumulated in soft tissues in a dose-dependent manner. After 4 and 7 weeks of exposure, the no observed effect concentration (NOEC) of Cd was 10 μg l -1 and the lowest observed effect concentration (LOEC) was 32 μg l -1 . Reduction of growth (decrease in wet weight) was noticed followed by a high mortality in higher Cd concentrations. Significant reduction in food consumption and growth rates was found at 32 μg l -1 and above Cd concentration. A significant relationship between Cd exposure and growth and feeding rates was noticed. The results obtained with these key aquatic organisms in the food chains complement those obtained with other aquatic organisms and gastropod snails. The findings of the present study and those of earlier studies suggested that Indian pond snail L. luteola are useful test organisms for ecotoxicology bioassays.

DNA multigene sequencing of topotypic specimens of the fascioliasis vector Lymnaea diaphana and phylogenetic analysis of the genus Pectinidens (Gastropoda

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Maria Dolores Bargues

2012-02-01

Full Text Available Freshwater lymnaeid snails are crucial in defining transmission and epidemiology of fascioliasis. In South America, human endemic areas are related to high altitudes in Andean regions. The species Lymnaea diaphana has, however, been involved in low altitude areas of Chile, Argentina and Peru where human infection also occurs. Complete nuclear ribosomal DNA 18S, internal transcribed spacer (ITS-2 and ITS-1 and fragments of mitochondrial DNA 16S and cytochrome c oxidase (cox1 genes of L. diaphana specimens from its type locality offered 1,848, 495, 520, 424 and 672 bp long sequences. Comparisons with New and Old World Galba/Fossaria, Palaearctic stagnicolines, Nearctic stagnicolines, Old World Radix and Pseudosuccinea allowed to conclude that (i L. diaphana shows sequences very different from all other lymnaeids, (ii each marker allows its differentiation, except cox1 amino acid sequence, and (iii L. diaphana is not a fossarine lymnaeid, but rather an archaic relict form derived from the oldest North American stagnicoline ancestors. Phylogeny and large genetic distances support the genus Pectinidens as the first stagnicoline representative in the southern hemisphere, including colonization of extreme world regions, as most southern Patagonia, long time ago. The phylogenetic link of L. diaphana with the stagnicoline group may give light to the aforementioned peculiar low altitude epidemiological scenario of fascioliasis.

Distribution and habitats of the snail Lymnaea truncatula, intermediate host of the liver fluke Fasciola hepatica, in South Africa

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K.N. de Kock

2003-07-01

Full Text Available This paper focuses on the geographical distribution and habitats of Lymnaea truncatula, the intermediate, snail host of the liver fluke, Fasciola hepatica, as reflected by the 723 samples in the database of the National Freshwater Snail Collection, Potchefstroom, South Africa. The 221 different loci (1/16-degree squares on record reflect an extensive but discontinuous distribution, except in Lesotho and in parts of the Mpumalanga, Gauteng and North West provinces of South Africa. Although recorded from 12 different types of waterbody, it was mostly (42.0 % recovered from swamps. Most samples (45.8 % were collected in habitats with slow-flowing water. A muddy substratum was recorded for 62.5 % of the samples. Most samples (86.3 % were collected in habitats with a mean annual air temperature of 10-20 o C, and more than 69 % came from localities with a mean annual rainfall of 600-900mm. An integrated decision tree constructed from the data indicated that temperature and types of waterbody play a decisive role in determining the presence of L. truncatula in a given area. A temperature index calculated for all mollusc species ranked L. truncatula second in a total of 53 species according to its association with low temperatures. It remains to be established whether its distribution is indeed discontinuous, and whether its preference for a particular habitat, amphibious habits and ability to aestivate could have resulted in some populations having been overlooked during surveys.

Assessment of anoxia tolerance and photoperiod dependence of GABAergic polarity in the pond snail Lymnaea stagnalis.

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Buck, Leslie T; Bond, Hilary C; Malik, Aqsa

2017-01-01

The pond snail Lymnaea stagnalis is reported to be anoxia-tolerant and if the tolerance mechanism is similar to that of the anoxia-tolerant painted turtle, GABA should play an important role. A potentially confounding factor investigating the role of GABA in anoxia tolerance are reports that GABA has both inhibitory and excitatory effects within L. stagnalis central ganglion. We therefore set out to determine if seasonality or photoperiod has an impact on: 1) the anoxia-tolerance of the intact pond snail, and 2) the response of isolated neuroganglia cluster F neurons to exogenous GABA application. L. stagnalis maintained on a natural summer light cycle were unable to survive any period of anoxic exposure, while those maintained on a natural winter light cycle survived a maximum of 4h. Using intracellular sharp electrode recordings from pedal ganglia cluster F neurons we show that there is a photoperiod dependent shift in the response to GABA. Snails exposed to a 16h:8h light:dark cycle in an environmental chamber (induced summer phenotype) exhibited hyperpolarizing inhibitory responses and those exposed to a 8h:16h light:dark cycle (induced winter phenotype) exhibited depolarizing excitatory responses to GABA application. Using gramicidin-perforated patch recordings we also found a photoperiod dependent shift in the reversal potential for GABA. We conclude that the opposing responses of L. stagnalis central neurons to GABA results from a shift in intracellular chloride concentration that is photoperiod dependent and is likely mediated through the relative efficacy of cation chloride co-transporters. Although the physiological ramifications of the photoperiod dependent shift are unknown this work potentially has important implications for the impact of artificial light pollution on animal health. Copyright © 2016 Elsevier Inc. All rights reserved.

The parasitic castration and gigantism of Lymnaea truncatula infected with the larval stages of Fasciola hepatica.

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Wilson, R A; Denison, J

1980-01-01

The shells of Lymnaea truncatula infected with the larval stages of Fasciola hepatica were significantly longer than those of comparable uninfected controls. The dry mass (tissue, shell + parasite) of the same infected snails, 56 days after infection, was approximately twice that of the controls (tissue + shell). The increased mass of infected snails was not due to a disproportionate increase in shell weight relative to tissues. Infected snails maintained at 20 degrees C had virtually ceased egg production by 21 days post-infection whereas control snails continued to lay eggs steadily for the duration of the experiment. The dry mass of snail tissue plus the cumulative dry weight of eggs produced was taken as an indication of the ability of control snails to generate biomass. Similarly the tissue mass plus cumulative egg weight and parasite weight was taken as an indication of the ability of the infected snails to generate biomass. The control and infected snails were not significantly different in this respect indicating that the gigantism of infected snails could be the result of a switch in nutrient supply from reproduction to somatic tissue growth and parasite growth. Castration was brought about 17-21 days after infection as a result of the direct consumption of the ovotestis by a proportion of the redial population. In a separate experiment it was demonstrated that a population of infected snails maintained at 20 degrees C survived as long as a similar group of control snails. The findings with this host-parasite system are discussed in relation to possible mechanisms causing castration and gigantism in other digene-snail interactions, and in relation to parasitic castration in other groups. It is concluded that the observed gigantism of infected snails is more likely to have a nutritional rather than endocrine origin.

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

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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 �

Distribution and habitats of Lymnaea natalensis, snail intermediate host of the liver fluke Fasciola gigantica, in South Africa

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Editorial Office

2001-09-01

Full Text Available This paper focuses on the geographical distribution and the habitats of Lymnaea natalensis, the snail intermediate host of the liver fluke, Fasciola gigantica, as reflected by the collection sites of its 4 552 samples currently on record in the National Freshwater Snail Collection (NFSC of South Africa. Although this species was represented in a variety of waterbodies, the majority of samples(±70%came from rivers, brooks and dams and in 70.8% of the cases the water was described as permanent and in 71.8% as slow flowing or standing. The results of life-table studies conducted by various authors indicated that temperature should be a relatively unimportant factor in determining its geographical distribution, but that the availability of permanent water should be decisive for its presence in a given habitat. These results are in agreement with the finding that only 7.5% of the samples of this species in the NFSC were collected in habitats which were described as seasonal. Furthermore, it gives a logical explanation for the sporadic occurrence, or total absence of this species in the more arid regions of South Africa. Water impoundments and irrigation networks contribute to a large extent towards creating perennial habitats which would be suitable for L. natalensis. As intermediate host for one of the liver fluke species which already is an economic factor in South Africa, this certainly is an aspect which ought to be reckoned within the planning and construction of new irrigation schemes.

Expansion of banana (Musa acuminata) gene families involved in ethylene biosynthesis and signalling after lineage-specific whole-genome duplications.

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Jourda, Cyril; Cardi, Céline; Mbéguié-A-Mbéguié, Didier; Bocs, Stéphanie; Garsmeur, Olivier; D'Hont, Angélique; Yahiaoui, Nabila

2014-05-01

Whole-genome duplications (WGDs) are widespread in plants, and three lineage-specific WGDs occurred in the banana (Musa acuminata) genome. Here, we analysed the impact of WGDs on the evolution of banana gene families involved in ethylene biosynthesis and signalling, a key pathway for banana fruit ripening. Banana ethylene pathway genes were identified using comparative genomics approaches and their duplication modes and expression profiles were analysed. Seven out of 10 banana ethylene gene families evolved through WGD and four of them (1-aminocyclopropane-1-carboxylate synthase (ACS), ethylene-insensitive 3-like (EIL), ethylene-insensitive 3-binding F-box (EBF) and ethylene response factor (ERF)) were preferentially retained. Banana orthologues of AtEIN3 and AtEIL1, two major genes for ethylene signalling in Arabidopsis, were particularly expanded. This expansion was paralleled by that of EBF genes which are responsible for control of EIL protein levels. Gene expression profiles in banana fruits suggested functional redundancy for several MaEBF and MaEIL genes derived from WGD and subfunctionalization for some of them. We propose that EIL and EBF genes were co-retained after WGD in banana to maintain balanced control of EIL protein levels and thus avoid detrimental effects of constitutive ethylene signalling. In the course of evolution, subfunctionalization was favoured to promote finer control of ethylene signalling. © 2014 CIRAD New Phytologist © 2014 New Phytologist Trust.

Lymnaea schirazensis, an Overlooked Snail Distorting Fascioliasis Data: Genotype, Phenotype, Ecology, Worldwide Spread, Susceptibility, Applicability

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Bargues, María Dolores; Artigas, Patricio; Khoubbane, Messaoud; Flores, Rosmary; Glöer, Peter; Rojas-García, Raúl; Ashrafi, Keyhan; Falkner, Gerhard; Mas-Coma, Santiago

2011-01-01

Background Lymnaeid snails transmit medical and veterinary important trematodiases, mainly fascioliasis. Vector specificity of fasciolid parasites defines disease distribution and characteristics. Different lymnaeid species appear linked to different transmission and epidemiological patterns. Pronounced susceptibility differences to absolute resistance have been described among lymnaeid populations. When assessing disease characteristics in different endemic areas, unexpected results were obtained in studies on lymnaeid susceptibility to Fasciola. We undertook studies to understand this disease transmission heterogeneity. Methodology/Principal Findings A ten-year study in Iran, Egypt, Spain, the Dominican Republic, Mexico, Venezuela, Ecuador and Peru, demonstrated that such heterogeneity is not due to susceptibility differences, but to a hitherto overlooked cryptic species, Lymnaea schirazensis, confused with the main vector Galba truncatula and/or other Galba/Fossaria vectors. Nuclear rDNA and mtDNA sequences and phylogenetic reconstruction highlighted an old evolutionary divergence from other Galba/Fossaria species, and a low intraspecific variability suggesting a recent spread from one geographical source. Morphometry, anatomy and egg cluster analyses allowed for phenotypic differentiation. Selfing, egg laying, and habitat characteristics indicated a migration capacity by passive transport. Studies showed that it is not a vector species (n = 8572 field collected, 20 populations): snail finding and penetration by F. hepatica miracidium occur but never lead to cercarial production (n = 338 experimentally infected). Conclusions/Significance This species has been distorting fasciolid specificity/susceptibility and fascioliasis geographical distribution data. Hence, a large body of literature on G. truncatula should be revised. Its existence has henceforth to be considered in research. Genetic data on livestock, archeology and history along the 10,000-year

Lymnaea schirazensis, an overlooked snail distorting fascioliasis data: genotype, phenotype, ecology, worldwide spread, susceptibility, applicability.

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María Dolores Bargues

Full Text Available BACKGROUND: Lymnaeid snails transmit medical and veterinary important trematodiases, mainly fascioliasis. Vector specificity of fasciolid parasites defines disease distribution and characteristics. Different lymnaeid species appear linked to different transmission and epidemiological patterns. Pronounced susceptibility differences to absolute resistance have been described among lymnaeid populations. When assessing disease characteristics in different endemic areas, unexpected results were obtained in studies on lymnaeid susceptibility to Fasciola. We undertook studies to understand this disease transmission heterogeneity. METHODOLOGY/PRINCIPAL FINDINGS: A ten-year study in Iran, Egypt, Spain, the Dominican Republic, Mexico, Venezuela, Ecuador and Peru, demonstrated that such heterogeneity is not due to susceptibility differences, but to a hitherto overlooked cryptic species, Lymnaea schirazensis, confused with the main vector Galba truncatula and/or other Galba/Fossaria vectors. Nuclear rDNA and mtDNA sequences and phylogenetic reconstruction highlighted an old evolutionary divergence from other Galba/Fossaria species, and a low intraspecific variability suggesting a recent spread from one geographical source. Morphometry, anatomy and egg cluster analyses allowed for phenotypic differentiation. Selfing, egg laying, and habitat characteristics indicated a migration capacity by passive transport. Studies showed that it is not a vector species (n = 8572 field collected, 20 populations: snail finding and penetration by F. hepatica miracidium occur but never lead to cercarial production (n = 338 experimentally infected. CONCLUSIONS/SIGNIFICANCE: This species has been distorting fasciolid specificity/susceptibility and fascioliasis geographical distribution data. Hence, a large body of literature on G. truncatula should be revised. Its existence has henceforth to be considered in research. Genetic data on livestock, archeology and history

Repetitive part of the banana (Musa acuminata) genome investigated by low-depth 454 sequencing.

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Hribová, Eva; Neumann, Pavel; Matsumoto, Takashi; Roux, Nicolas; Macas, Jirí; Dolezel, Jaroslav

2010-09-16

Bananas and plantains (Musa spp.) are grown in more than a hundred tropical and subtropical countries and provide staple food for hundreds of millions of people. They are seed-sterile crops propagated clonally and this makes them vulnerable to a rapid spread of devastating diseases and at the same time hampers breeding improved cultivars. Although the socio-economic importance of bananas and plantains cannot be overestimated, they remain outside the focus of major research programs. This slows down the study of nuclear genome and the development of molecular tools to facilitate banana improvement. In this work, we report on the first thorough characterization of the repeat component of the banana (M. acuminata cv. 'Calcutta 4') genome. Analysis of almost 100 Mb of sequence data (0.15× genome coverage) permitted partial sequence reconstruction and characterization of repetitive DNA, making up about 30% of the genome. The results showed that the banana repeats are predominantly made of various types of Ty1/copia and Ty3/gypsy retroelements representing 16 and 7% of the genome respectively. On the other hand, DNA transposons were found to be rare. In addition to new families of transposable elements, two new satellite repeats were discovered and found useful as cytogenetic markers. To help in banana sequence annotation, a specific Musa repeat database was created, and its utility was demonstrated by analyzing the repeat composition of 62 genomic BAC clones. A low-depth 454 sequencing of banana nuclear genome provided the largest amount of DNA sequence data available until now for Musa and permitted reconstruction of most of the major types of DNA repeats. The information obtained in this study improves the knowledge of the long-range organization of banana chromosomes, and provides sequence resources needed for repeat masking and annotation during the Musa genome sequencing project. It also provides sequence data for isolation of DNA markers to be used in genetic

Crystal structure of Lymnaea stagnalis AChBP complexed with the potent nAChR antagonist DHβE suggests a unique mode of antagonism.

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Azadeh Shahsavar

Full Text Available Nicotinic acetylcholine receptors (nAChRs are pentameric ligand-gated ion channels that belong to the Cys-loop receptor superfamily. These receptors are allosteric proteins that exist in different conformational states, including resting (closed, activated (open, and desensitized (closed states. The acetylcholine binding protein (AChBP is a structural homologue of the extracellular ligand-binding domain of nAChRs. In previous studies, the degree of the C-loop radial extension of AChBP has been assigned to different conformational states of nAChRs. It has been suggested that a closed C-loop is preferred for the active conformation of nAChRs in complex with agonists whereas an open C-loop reflects an antagonist-bound (closed state. In this work, we have determined the crystal structure of AChBP from the water snail Lymnaea stagnalis (Ls in complex with dihydro-β-erythroidine (DHβE, which is a potent competitive antagonist of nAChRs. The structure reveals that binding of DHβE to AChBP imposes closure of the C-loop as agonists, but also a shift perpendicular to previously observed C-loop movements. These observations suggest that DHβE may antagonize the receptor via a different mechanism compared to prototypical antagonists and toxins.

Elimination of Biomphalaria pfeifferi, Bulinus tropicus and Lymnaea natalensis by the ampullarid snail, Marisa cornuarietis, in a man-made dam in northern Tanzania.

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Nguma, J F; McCullough, F S; Masha, E

1982-03-01

Marisa cornuarietis is a well known ampullarid competitor/predator of Biomphalaria glabrata in Puerto Rico. For the first time in Africa a flourishing population of Marisa has been established in a small, permanent, man-made dam at Kisangara, near Moshi, Tanzania. Prior to the release of M. cornuarietis in June 1977, this dam supported thriving populations of the pulmonate snail hosts Biomphalaria pfeifferi and Lymnaea natalensis; Bulinus tropicus and the melaniid Melanoides tuberculata were also common. Some 24 months after the establishment of Marisa the three pulmonate species had been eliminated; only M. tuberculata remained at about the same population density as originally recorded. Marisa has not caused any obvious adverse environmental impact in the dam. There is at present no valid evidence that this ampullarid would be a threat to local rice production, which is the only crop at risk, but carefully designed field trials should be undertaken to confirm or refute this view. In view of the vast number of permanent, lentic habitats throughout the Afrotropical region, which act as important transmission sites of schistosomiasis and fascioliasis, the role of Marisa cornuarietis as a cost-effective biological control agent in integrated control operations deserves henceforth to be energetically explored.

Development of an Ionic Liquid-Based Ultrasonic/Microwave-Assisted Simultaneous Distillation and Extraction Method for Separation of Camptothecin, 10-Hydroxycamptothecin, Vincoside-Lactam, and Essential Oils from the Fruits of Camptotheca acuminata Decne

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Chunjian Zhao

2016-10-01

Full Text Available An ionic liquid-based ultrasonic/microwave-assisted simultaneous distillation and extraction (IL-UMASDE method for isolating camptothecin (CPT, 10-hydroxycamptothecin (HCPT, vincoside-lactam (VCS-LT, and essential oils (EOs from Camptotheca acuminata Decne fruits was developed. The important parameters were optimized using single-factor and central composite design experiments. The optimum conditions were 0.75 M 1-octyl-3-methylimidazolium ([C8mim]Br as the extraction solvent, a liquid–solid ratio of 13.7 mL/g, an extraction time of 33.2 min, a microwave power of 582 W, and a fixed ultrasonic power of 50 W. The yields of CPT, HCPT, and VCS-LT obtained under the optimum conditions were 2.463, 0.164, and 0.297 mg/g, respectively; these are 1.08-, 1.12-, and 1.04-fold higher, respectively, than those obtained by conventional 55% ethanol heat reflux extraction (HRE. The extraction time for the equilibrium yields of CPT, HCPT and VCS-LT using IL-UMASDE was 33.6%, 58.5%, 63.1%, and 66.8%, respectively, less than the corresponding times using IL-MASDE, IL-ultrasonic-assisted extraction (IL-UAE, 55% ethanol UAE and 55% ethanol HRE. The yield of EOs obtained using IL-UMASDE was 0.793 mg/g, i.e., 1.31-fold higher than that obtained by conventional hydrodistillation extraction (HDE. The components of the EOs obtained using IL-UMASDE and HDE were similar. The extraction time for the equilibrium yields of EOs using IL-UMASDE is 33.6%, 58.5%, 52.6%, and 72.3% lower than those for IL-MASDE, water-UMASDE, water-MASDE, and HDE, respectively. Compared with other extraction methods, IL-UMASDE gave the highest yields of CPT, HCPT, VCS-LT, and EOs and also had the shortest extraction time. IL-UMASDE is a potential green and highly efficient technique for the extraction of CPT, HCPT, VCS-LT, and EOs from Camptotheca acuminata Decne fruits.

Larval trematodes (Digenea of the great pond snail, Lymnaea stagnalis (L., (Gastropoda, Pulmonata in Central Europe: a survey of species and key to their identification

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Faltýnková A.

2007-03-01

Full Text Available A survey of cercariae and metacercariae (Trematoda, Digenea from the great pond snail (Lymnaea stagnalis in Central Europe (Austria, Czech Republic, South-East Germany, Poland and Slovak Republic is presented, based on a study of 3,628 snails examined from 1998 to 2005. A total of 953 (26.3% L. stagnalis were infected with 24 trematode species comprising 19 species of cercariae and 11 species of metacercariae (six species occurred both as cercarie and metacercarie of eight families. The dominant cercariae were those of Opisthioglyphe ranae (159 hosts infected, Plagiorchis elegans (141 (both family Plagiorchiidae and Echinoparyphium aconiatum (153 (Echinostomatidae; 14 double infections were found. The most frequent metacercariae were those of Neoglyphe locellus (71 (Omphalometridae, E. aconiatum (66, Echinostoma sp. (59 and Moliniella anceps (48 (Echinostomatidae. In the previous studies carried out in Central Europe, a very similar spectrum of nine trematode families of 22 cercariae determined to species level and 43 types of cercariae reported under generic or provisional names, which can be in many cases conspecific with the previous taxa, were found. A simple key to identification of cercariae and metacercariae, together with their illustrations, is provided.

Cloning of an ADP-ribosylation factor gene from banana (Musa acuminata) and its expression patterns in postharvest ripening fruit.

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Wang, Yuan; Wu, Jing; Xu, Bi-Yu; Liu, Ju-Hua; Zhang, Jian-Bin; Jia, Cai-Hong; Jin, Zhi-Qiang

2010-08-15

A full-length cDNA encoding an ADP-ribosylation factor (ARF) from banana (Musa acuminata) fruit was cloned and named MaArf. It contains an open reading frame encoding a 181-amino-acid polypeptide. Sequence analysis showed that MaArf shared high similarity with ARF of other plant species. The genomic sequence of MaArf was also obtained using polymerase chain reaction (PCR). Sequence analysis showed that MaArf was a split gene containing five exons and four introns in genomic DNA. Reverse-transcriptase PCR was used to analyze the spatial expression of MaArf. The results showed that MaArf was expressed in all the organs examined: root, rhizome, leaf, flower and fruit. Real-time quantitative PCR was used to explore expression patterns of MaArf in postharvest banana. There was differential expression of MaArf associated with ethylene biosynthesis. In naturally ripened banana, expression of MaArf was in accordance with ethylene biosynthesis. However, in 1-methylcyclopropene-treated banana, the expression of MaArf was inhibited and changed little. When treated with ethylene, MaArf expression in banana fruit significantly increased in accordance with ethylene biosynthesis; the peak of MaArf was 3 d after harvest, 11 d earlier than for naturally ripened banana fruits. These results suggest that MaArf is induced by ethylene in regulating postharvest banana ripening. Finally, subcellular localization assays showed the MaArf protein in the cytoplasm. Copyright 2010 Elsevier GmbH. All rights reserved.

Considerations for test design to accommodate energy-budget models in ecotoxicology: a case study for acetone in the pond snail Lymnaea stagnalis.

Science.gov (United States)

Barsi, Alpar; Jager, Tjalling; Collinet, Marc; Lagadic, Laurent; Ducrot, Virginie

2014-07-01

Toxicokinetic-toxicodynamic (TKTD) modeling offers many advantages in the analysis of ecotoxicity test data. Calibration of TKTD models, however, places different demands on test design compared with classical concentration-response approaches. In the present study, useful complementary information is provided regarding test design for TKTD modeling. A case study is presented for the pond snail Lymnaea stagnalis exposed to the narcotic compound acetone, in which the data on all endpoints were analyzed together using a relatively simple TKTD model called DEBkiss. Furthermore, the influence of the data used for calibration on accuracy and precision of model parameters is discussed. The DEBkiss model described toxic effects on survival, growth, and reproduction over time well, within a single integrated analysis. Regarding the parameter estimates (e.g., no-effect concentration), precision rather than accuracy was affected depending on which data set was used for model calibration. In addition, the present study shows that the intrinsic sensitivity of snails to acetone stays the same across different life stages, including the embryonic stage. In fact, the data on egg development allowed for selection of a unique metabolic mode of action for the toxicant. Practical and theoretical considerations for test design to accommodate TKTD modeling are discussed in the hope that this information will aid other researchers to make the best possible use of their test animals. © 2014 SETAC.

Lipoidal labellar secretions in Maxillaria ruiz & pav. (Orchidaceae).

Science.gov (United States)

Davies, K L; Turner, M P; Gregg, A

2003-03-01

The labella of Maxillaria acuminata Lindl., M. cerifera Barb. Rodr. and M. notylioglossa Rchb.f., all members of the M. acuminata alliance, produce a viscid wax-like secretion. Histochemical analysis revealed that the chemical composition of the secretion is similar in all three species, consisting largely of lipid and protein. Light microscopy and low-vacuum scanning electron microscopy were used to investigate the secretory process. In a fourth taxon, M. cf. notylioglossa, transmission electron microscopy showed that lipid bodies are associated with smooth endoplasmic reticulum or occur as plastoglobuli within plastids. Lipid bodies vary in appearance and this may reflect differences in chemical composition. They become associated with the plasmalemma and eventually accumulate between the latter and the cell wall. The wall contains no pits or ectodesmata, and it is speculated that lipid passes through the wall as small lipid moieties before eventually reassembling to form lipid globules on the external surface of the cuticle. These globules are able to coalesce forming extensive viscid areas on the labellum. The possible significance of this process to pollination is discussed.

Proteomic Analysis of the Reproductive Organs of the Hermaphroditic Gastropod Lymnaea stagnalis Exposed to Different Endocrine Disrupting Chemicals

Science.gov (United States)

Giusti, Arnaud; Leprince, Pierre; Mazzucchelli, Gabriel; Thomé, Jean-Pierre; Lagadic, Laurent; Ducrot, Virginie; Joaquim-Justo, Célia

2013-01-01

Many studies have reported perturbations of mollusc reproduction following exposure to low concentrations (ng/L range) of endocrine disrupting chemicals (EDCs). However, the mechanisms of action of these molecules on molluscs are still poorly understood. Investigation of the modifications of protein expression in organisms exposed to chemicals using proteomic methods can provide a broader and more comprehensive understanding of adverse impacts of pollution on organisms than conventional biochemical biomarkers (e.g., heat-shock proteins, metallothioneins, GST, EROD). In this study we have investigated the impacts of four chemicals, which exhibit different endocrine disrupting properties in vertebrates, on the proteome of the hermaphroditic freshwater pulmonate gastropod Lymnaea stagnalis after 21 days of exposure. Testosterone, tributyltin, chlordecone and cyproterone acetate were chosen as tested compounds as they can induce adverse effects on the reproduction of this snail. The 2D-DIGE method was used to identify proteins whose expression was affected by these compounds. In addition to modifying the expression of proteins involved in the structure and function of the cytoskeleton, chemicals had impacts on the expression of proteins involved in the reproduction of L. stagnalis. Exposure to 19.2 µg/L of chlordecone increased the abundance of ovipostatin, a peptide transmitted during mating through seminal fluid, which reduces oviposition in this species. The expression of yolk ferritin, the vitellogenin equivalent in L. stagnalis, was reduced after exposure to 94.2 ng Sn/L of tributyltin. The identification of yolk ferritin and the modification of its expression in snails exposed to chemicals were refined using western blot analysis. Our results showed that the tested compounds influenced the abundance of yolk ferritin in the reproductive organs. Alteration in proteins involved in reproductive pathways (e.g., ovipostatin and yolk ferritin) could constitute relevant

Dietary Administration of Banana (Musa acuminata Peel Flour Affects the Growth, Antioxidant Status, Cytokine Responses, and Disease Susceptibility of Rohu, Labeo rohita

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Sib Sankar Giri

2016-01-01

Full Text Available To explore the feasibility of Musa acuminata (banana peels as a feed additive, effects of banana peel flour (BPF on the growth and immune functions of Labeo rohita were evaluated. Diets containing five different concentrations of BPF (0% [basal diet], 1% [B1], 3% [B3], 5% [B5], and 7% [B7] were fed to the fish (average weight: 15.3 g for 60 days. The final weight gain and specific growth rate were higher (P<0.05 in the B5 group. The most significant improvements in immune parameters such as lysozyme, alternative complement pathway, leukocyte phagocytic, superoxide dismutase, and catalase activities were observed in the B5 group. However, the B5 group exhibited the lowest malondialdehyde activity. IgM and glutathione peroxidise activities were significantly elevated in the treatment groups, except in B1, after only 30 days of feeding. Of the examined cytokine-related genes, IL-1β, TNF-α, and HSP70 were upregulated in the head kidney and hepatopancreas, and expressions were generally higher in the B3 and B5 groups. Moreover, B5 group challenged with Aeromonas hydrophila 60 days after feeding exhibited the highest survival rate (70%; P<0.05. These results suggest that dietary BPF at 5% could promote growth performance and strengthen immunity in L. rohita.

Dietary Administration of Banana (Musa acuminata) Peel Flour Affects the Growth, Antioxidant Status, Cytokine Responses, and Disease Susceptibility of Rohu, Labeo rohita.

Science.gov (United States)

Giri, Sib Sankar; Jun, Jin Woo; Sukumaran, Venkatachalam; Park, Se Chang

2016-01-01

To explore the feasibility of Musa acuminata (banana) peels as a feed additive, effects of banana peel flour (BPF) on the growth and immune functions of Labeo rohita were evaluated. Diets containing five different concentrations of BPF (0% [basal diet], 1% [B1], 3% [B3], 5% [B5], and 7% [B7]) were fed to the fish (average weight: 15.3 g) for 60 days. The final weight gain and specific growth rate were higher (P < 0.05) in the B5 group. The most significant improvements in immune parameters such as lysozyme, alternative complement pathway, leukocyte phagocytic, superoxide dismutase, and catalase activities were observed in the B5 group. However, the B5 group exhibited the lowest malondialdehyde activity. IgM and glutathione peroxidise activities were significantly elevated in the treatment groups, except in B1, after only 30 days of feeding. Of the examined cytokine-related genes, IL-1β, TNF-α, and HSP70 were upregulated in the head kidney and hepatopancreas, and expressions were generally higher in the B3 and B5 groups. Moreover, B5 group challenged with Aeromonas hydrophila 60 days after feeding exhibited the highest survival rate (70%; P < 0.05). These results suggest that dietary BPF at 5% could promote growth performance and strengthen immunity in L. rohita.

Cell cycle-related fluctuations in transcellular ionic currents and plasma membrane Ca2+/Mg2+ ATPase activity during early cleavages of Lymnaea stagnalis embryos.

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Zivkovic, Danica; Créton, Robbert; Dohmen, René

1991-08-01

During the first four mitotic division cycles of Lymnaea stagnalis embryos, we have detected cell cycle-dependent changes in the pattern of transcellular ionic currents and membrane-bound Ca 2+ -stimulated ATPase activity. Ionic currents ranging from 0.05 to 2.50 μA/cm 2 have been measured using the vibrating probe technique. Enzyme activity was detected using Ando's cytochemical method (Ando et al. 1981) which reveals Ca 2+ /Mg 2+ ATPase localization at the ultrastructural level, and under high-stringency conditions with respect to calcium availability, it reveals Ca 2+ -stimulated ATPase. The ionic currents and Ca 2+ -stimulated ATPase localization have in common that important changes occur during the M-phase of the cell cycles. Minimal outward current at the vegetal pole coincides with metaphase/anaphase. Maximal inward current at the animal pole coincides with the onset of cytokinesis at that pole. Ca 2+ -stimulated ATPase is absent from one half of the embryo at metaphase/anaphase of the two- and four-cell stage, whereas it is present in all cells during the remaining part of the cell cycle. Since fluctuations of cytosolic free calcium concentrations appear to correlate with both karyokinesis and cytokinesis, we speculate that part of the cyclic pattern of Ca 2+ -stimulated ATPase localization and of the transcellular ionic currents reflects the elevation of cytosolic free calcium concentration during the M-phase.

EIN3-like gene expression during fruit ripening of Cavendish banana (Musa acuminata cv. Grande naine).

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Mbéguié-A-Mbéguié, Didier; Hubert, Olivier; Fils-Lycaon, Bernard; Chillet, Marc; Baurens, Franc-Christophe

2008-06-01

Ethylene signal transduction initiates with ethylene binding at receptor proteins and terminates in a transcription cascade involving the EIN3/EIL transcription factors. Here, we have isolated four cDNAs homologs of the Arabidopsis EIN3/EIN3-like gene, MA-EILs (Musa acuminata ethylene insensitive 3-like) from banana fruit. Sequence comparison with other banana EIL gene already registered in the database led us to conclude that, at this day, at least five different genes namely MA-EIL1, MA-EIL2/AB266318, MA-EIL3/AB266319, MA-EIL4/AB266320 and AB266321 exist in banana. Phylogenetic analyses included all banana EIL genes within a same cluster consisting of rice OsEILs, a monocotyledonous plant as banana. However, MA-EIL1, MA-EIL2/AB266318, MA-EIL4/AB266320 and AB266321 on one side, and MA-EIL3/AB266319 on the other side, belong to two distant subclusters. MA-EIL mRNAs were detected in all examined banana tissues but at lower level in peel than in pulp. According to tissues, MA-EIL genes were differentially regulated by ripening and ethylene in mature green fruit and wounding in old and young leaves. MA-EIL2/AB266318 was the unique ripening- and ethylene-induced gene; MA-EIL1, MA-EIL4/Ab266320 and AB266321 genes were downregulated, while MA-EIL3/AB266319 presented an unusual pattern of expression. Interestingly, a marked change was observed mainly in MA-EIL1 and MA-EIL3/Ab266319 mRNA accumulation concomitantly with changes in ethylene responsiveness of fruit. Upon wounding, the main effect was observed in MA-EIL4/AB266320 and AB266321 mRNA levels, which presented a markedly increase in both young and old leaves, respectively. Data presented in this study suggest the importance of a transcriptionally step control in the regulation of EIL genes during banana fruit ripening.

Direct Effects Of Chronic Gamma Radiation On Musa Acuminata Var. Berangan, A Local Malaysia Banana Cultivar

International Nuclear Information System (INIS)

Maimum Tahir; Azhar Mohamad; Rozeita Laboh; Umikalsum Mohd Bahari

2014-01-01

Musa acuminata var. Berangan, is a popular variety of our local banana known as Pisang Berangan. The variety is a triploid banana, use mainly for dessert and has a great value for commodity fruit crops. However, production of PisangBerangan has been threatened by diseases such as Fusarium wilt, black sigatoka, Fusarium wilt, burrowing nematodes and viral diseases like Banana streak virus, Banana bunch top virus and Banana bract mosaic virus. The scenario becoming worst as Musa has a narrow genetic background for breeding and/or selection program. The banana breeding program of edible bananas is hampered by high sterility, and very limited amounts of seeds. Mutation induction via chronic gamma radiation is an alternative ways in creating more variants for selections towards a better quality and disease tolerance. A total number of 75 samples at nursery stage (1 month) were exposed to chronic gamma radiation in Gamma Greenhouse at Malaysian Nuclear Agency for 28 weeks. The samples were accordingly arranged with distance ranging from 1 m to 15 m from gamma source (Cesium-137). Plant height and new buds were used as measurement parameters in evaluating the direct effects of the chronic gamma radiation. Results showed effective dose of chronic gamma radiation in Pisang Berangan was 20 Gy. Number of new emerging sucker was ranging from 1-3 pieces with the highest at ring-4 and ring-5. Plant height was observed ranging from 22.1 to 110.5 cm. Effects of chronic radiation were observed after 3-4 months in the GGH. The samples revealed as striking leaves, short inter node and new emergence of suckers. The objective of this work is to get a dose response for chronic gamma radiation in Pisang Berangan. As for selection of potential mutant variants, new emerging suckers were tissue cultured in segregating chimeras and to get required numbers of samples for further field evaluation. (author)

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.

Effects of gamma irradiation followed by climatization on the quality of 'Prata' banana (Musa acuminata x Musa balbisiana, AAB)

International Nuclear Information System (INIS)

Martineli, Maristella; Coneglian, Regina C.C.; Vasconcellos, Marco A.S.; Silva, Eduardo; Rocha, Janielio G.; Melo, Maruzanete P.; Vital, Helio C.

2009-01-01

Banana is a highly perishable climacteric fruit. In order to ensure fast and homogeneous ripening that will make its processing and commercialization easier, it is usually treated by climatization. On the other hand, irradiation is an interesting physical process capable of delaying ripening and extending the shelf life of fruits. This work investigated the competing effects of irradiation followed by climatization on the quality of 'Prata' banana (Musa acuminata x Musa balbisiana, AAB). All fruits were harvested in the preclimacteric stage, rinsed and stored at 27 deg C after being submitted to five different treatments. After hygienization, four out of five samples were exposed to gamma-ray at doses of 0.25 and 0.50 kGy. The unirradiated fruits were left for control and half of the irradiated samples were then climatized by exposure to CaC 2 . Measurements of fresh mass loss, total soluble solids, peel coloration and disease index were performed on five different dates for up to nine days in order to monitor quality and the degree of ripening. It was found that high temperatures prevailing during climatization and storage accelerated maturation in all fruits in spite of the use of irradiation, with the control becoming ripe in 3 days only. In addition, based on the consistent results from the experiments performed, it can be concluded that irradiation at the doses tested was unable to overcome the maturation effects produced by climatization. However, the sole use of irradiation with 0.25 kGy yielded the lowest figures for fresh mass loss and disease index in the samples, thus becoming the most attractive among the treatments tested. (author)

Fascioliasis transmission by Lymnaea neotropica confirmed by nuclear rDNA and mtDNA sequencing in Argentina.

Science.gov (United States)

Mera y Sierra, Roberto; Artigas, Patricio; Cuervo, Pablo; Deis, Erika; Sidoti, Laura; Mas-Coma, Santiago; Bargues, Maria Dolores

2009-12-03

Fascioliasis is widespread in livestock in Argentina. Among activities included in a long-term initiative to ascertain which are the fascioliasis areas of most concern, studies were performed in a recreational farm, including liver fluke infection in different domestic animal species, classification of the lymnaeid vector and verification of natural transmission of fascioliasis by identification of the intramolluscan trematode larval stages found in naturally infected snails. The high prevalences in the domestic animals appeared related to only one lymnaeid species present. Lymnaeid and trematode classification was verified by means of nuclear ribosomal DNA and mitochondrial DNA marker sequencing. Complete sequences of 18S rRNA gene and rDNA ITS-2 and ITS-1, and a fragment of the mtDNA cox1 gene demonstrate that the Argentinian lymnaeid belongs to the species Lymnaea neotropica. Redial larval stages found in a L. neotropica specimen were ascribed to Fasciola hepatica after analysis of the complete ITS-1 sequence. The finding of L. neotropica is the first of this lymnaeid species not only in Argentina but also in Southern Cone countries. The total absence of nucleotide differences between the sequences of specimens from Argentina and the specimens from the Peruvian type locality at the levels of rDNA 18S, ITS-2 and ITS-1, and the only one mutation at the mtDNA cox1 gene suggest a very recent spread. The ecological characteristics of this lymnaeid, living in small, superficial water collections frequented by livestock, suggest that it may be carried from one place to another by remaining in dried mud stuck to the feet of transported animals. The presence of L. neotropica adds pronounced complexity to the transmission and epidemiology of fascioliasis in Argentina, due to the great difficulties in distinguishing, by traditional malacological methods, between the three similar lymnaeid species of the controversial Galba/Fossaria group present in this country: L. viatrix

The population density of Lymnaea columella (Say, 1817) (Mollusca, Lymnaeidae) an intermediate host of Fasciola hepatica (Linnaeus, 1758), in the Caparaó microregion, ES, Brazil.

Science.gov (United States)

D'Almeida, S C G; Freitas, D F; Carneiro, M B; Camargo, P F; Azevedo, J C; Martins, I V F

2016-06-01

The aim of this study was to monitor the population density of Lymnaea columella, an intermediate host of Fasciola hepatica, in various aquatic habitats and in drinking water in the area of the Instituto Federal de Educação, Ciência e Tecnologia do Espírito Santo, on Caparaó Microregion, municipality of Alegre, state of Espírito Santo, Brazil. Monthly samplings were performed at certain points between drainage areas and drinking water in cattle and goat production systems during the years 2010 to 2013. The mean temperature, precipitation and the frequency of samples of L. columella were analysed graphically according the monthly average during the study period. A total of 2,038 molluscs were collected, 1558 of which were L. columella, that predominated in all sampled points. The highest average of specimens observed for L. columella was in the years 2010 and 2013 (51.0), and occurred decreased in 2011 (19.8). The temperature and precipitation averaged is 23.7 °C and 141 mm/year, respectively. Rainfall peak occurred in March (2011, 2013) and November (2012), during these periods the population of L. columella growth. There was no significant difference in the relationship between the specimens observed with seasons (dry-wet), thus the population of L. columella remained stable and can be found throughout the year.

Proteomic analysis of the reproductive organs of the hermaphroditic gastropod Lymnaea stagnalis exposed to different endocrine disrupting chemicals.

Directory of Open Access Journals (Sweden)

Arnaud Giusti

Full Text Available Many studies have reported perturbations of mollusc reproduction following exposure to low concentrations (ng/L range of endocrine disrupting chemicals (EDCs. However, the mechanisms of action of these molecules on molluscs are still poorly understood. Investigation of the modifications of protein expression in organisms exposed to chemicals using proteomic methods can provide a broader and more comprehensive understanding of adverse impacts of pollution on organisms than conventional biochemical biomarkers (e.g., heat-shock proteins, metallothioneins, GST, EROD. In this study we have investigated the impacts of four chemicals, which exhibit different endocrine disrupting properties in vertebrates, on the proteome of the hermaphroditic freshwater pulmonate gastropod Lymnaea stagnalis after 21 days of exposure. Testosterone, tributyltin, chlordecone and cyproterone acetate were chosen as tested compounds as they can induce adverse effects on the reproduction of this snail. The 2D-DIGE method was used to identify proteins whose expression was affected by these compounds. In addition to modifying the expression of proteins involved in the structure and function of the cytoskeleton, chemicals had impacts on the expression of proteins involved in the reproduction of L. stagnalis. Exposure to 19.2 µg/L of chlordecone increased the abundance of ovipostatin, a peptide transmitted during mating through seminal fluid, which reduces oviposition in this species. The expression of yolk ferritin, the vitellogenin equivalent in L. stagnalis, was reduced after exposure to 94.2 ng Sn/L of tributyltin. The identification of yolk ferritin and the modification of its expression in snails exposed to chemicals were refined using western blot analysis. Our results showed that the tested compounds influenced the abundance of yolk ferritin in the reproductive organs. Alteration in proteins involved in reproductive pathways (e.g., ovipostatin and yolk ferritin could

Development and validation of an OECD reproductive toxicity test guideline with the pond snail Lymnaea stagnalis (Mollusca, Gastropoda).

Science.gov (United States)

Ducrot, Virginie; Askem, Clare; Azam, Didier; Brettschneider, Denise; Brown, Rebecca; Charles, Sandrine; Coke, Maïra; Collinet, Marc; Delignette-Muller, Marie-Laure; Forfait-Dubuc, Carole; Holbech, Henrik; Hutchinson, Thomas; Jach, Arne; Kinnberg, Karin L; Lacoste, Cédric; Le Page, Gareth; Matthiessen, Peter; Oehlmann, Jörg; Rice, Lynsey; Roberts, Edward; Ruppert, Katharina; Davis, Jessica Elphinstone; Veauvy, Clemence; Weltje, Lennart; Wortham, Ruth; Lagadic, Laurent

2014-12-01

The OECD test guideline development program has been extended in 2011 to establish a partial life-cycle protocol for assessing the reproductive toxicity of chemicals to several mollusk species, including the great pond snail Lymnaea stagnalis. In this paper, we summarize the standard draft protocol for a reproduction test with this species, and present inter-comparison results obtained in a 56-day prevalidation ring-test using this protocol. Seven European laboratories performed semi-static tests with cultured snails of the strain Renilys® exposed to nominal concentrations of cadmium chloride (from 53 to 608μgCdL(-1)). Cd concentrations in test solutions were analytically determined to confirm accuracy in the metal exposure concentrations in all laboratories. Physico-chemical and biological validity criteria (namely dissolved oxygen content >60% ASV, water temperature 20±1°C, control snail survival >80% and control snail fecundity >8 egg-masses per snail over the test period) were met in all laboratories which consistently demonstrated the reproductive toxicity of Cd in snails using the proposed draft protocol. Effect concentrations for fecundity after 56days were reproducible between laboratories (68

The transcriptional regulatory network mediated by banana (Musa acuminata) dehydration-responsive element binding (MaDREB) transcription factors in fruit ripening.

Science.gov (United States)

Kuang, Jian-Fei; Chen, Jian-Ye; Liu, Xun-Cheng; Han, Yan-Chao; Xiao, Yun-Yi; Shan, Wei; Tang, Yang; Wu, Ke-Qiang; He, Jun-Xian; Lu, Wang-Jin

2017-04-01

Fruit ripening is a complex, genetically programmed process involving the action of critical transcription factors (TFs). Despite the established significance of dehydration-responsive element binding (DREB) TFs in plant abiotic stress responses, the involvement of DREBs in fruit ripening is yet to be determined. Here, we identified four genes encoding ripening-regulated DREB TFs in banana (Musa acuminata), MaDREB1, MaDREB2, MaDREB3, and MaDREB4, and demonstrated that they play regulatory roles in fruit ripening. We showed that MaDREB1-MaDREB4 are nucleus-localized, induced by ethylene and encompass transcriptional activation activities. We performed a genome-wide chromatin immunoprecipitation and high-throughput sequencing (ChIP-Seq) experiment for MaDREB2 and identified 697 genomic regions as potential targets of MaDREB2. MaDREB2 binds to hundreds of loci with diverse functions and its binding sites are distributed in the promoter regions proximal to the transcriptional start site (TSS). Most of the MaDREB2-binding targets contain the conserved (A/G)CC(G/C)AC motif and MaDREB2 appears to directly regulate the expression of a number of genes involved in fruit ripening. In combination with transcriptome profiling (RNA sequencing) data, our results indicate that MaDREB2 may serve as both transcriptional activator and repressor during banana fruit ripening. In conclusion, our study suggests a hierarchical regulatory model of fruit ripening in banana and that the MaDREB TFs may act as transcriptional regulators in the regulatory network. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Morphological, molecular and ecological aspects of the South American hypogeous fungi Alpova austroalnicola sp. nov.

Science.gov (United States)

Eduardo R. Nouhra; Laura S. Domínguez; Alejandra G. Becerra; James M. Trappe

2005-01-01

Field studies in Argentina's Yunga District revealed Alpova austroalnicola sp. nov., a hypogeous fungus associated with Alnus acuminata ssp, acuminata. Morphological and molecular studies based on amplification and sequencing of the nuclear LSU rDNA gene showed its unique identity within ...

A Ser/Thr protein kinase phosphorylates MA-ACS1 (Musa acuminata 1-aminocyclopropane-1-carboxylic acid synthase 1) during banana fruit ripening.

Science.gov (United States)

Choudhury, Swarup Roy; Roy, Sujit; Sengupta, Dibyendu N

2012-08-01

1-Aminocyclopropane-1-carboxylic acid synthase (ACS) catalyzes the rate-limiting step in ethylene biosynthesis during ripening. ACS isozymes are regulated both transcriptionally and post-translationally. However, in banana, an important climacteric fruit, little is known about post-translational regulation of ACS. Here, we report the post-translational modification of MA-ACS1 (Musa acuminata ACS1), a ripening inducible isozyme in the ACS family, which plays a key role in ethylene biosynthesis during banana fruit ripening. Immunoprecipitation analyses of phospholabeled protein extracts from banana fruit using affinity-purified anti-MA-ACS1 antibody have revealed phosphorylation of MA-ACS1, particularly in ripe fruit tissue. We have identified the induction of a 41-kDa protein kinase activity in pulp at the onset of ripening. The 41-kDa protein kinase has been identified as a putative protein kinase by MALDI-TOF/MS analysis. Biochemical analyses using partially purified protein kinase fraction from banana fruit have identified the protein kinase as a Ser/Thr family of protein kinase and its possible involvement in MA-ACS1 phosphorylation during ripening. In vitro phosphorylation analyses using synthetic peptides and site-directed mutagenized recombinant MA-ACS1 have revealed that serine 476 and 479 residues at the C-terminal region of MA-ACS1 are phosphorylated. Overall, this study provides important novel evidence for in vivo phosphorylation of MA-ACS1 at the molecular level as a possible mechanism of post-translational regulation of this key regulatory protein in ethylene signaling pathway in banana fruit during ripening.

Caracterización de harina y almidón de frutos de banano Gros Michel (Musa acuminata AAA

Directory of Open Access Journals (Sweden)

Jairo Montoya-López

2015-01-01

Full Text Available En el estudio se determinaron las características fisicoquímicas, térmicas y reológicas de la harina y el almidón de frutos de banano Gros Michel (Musa acuminata cosechado en fincas del departamento del Quindío, Colombia. En el análisis proximal, la harina presentó un contenido de fibra de 18.82% y el almidón presentó contenidos de proteína de 1.92%, grasa de 5.3% y fibra de 2.76%. La harina presentó la temperatura más alta de absorción de calor (68.88 °C y su entalpía de gelatinización fue de 2.17 J/g; mientras que para el almidón estos valores fueron de 48.36 °C y 44.62 J/g, respectivamente. El análisis termogravimétrico (TGA de la harina o temperaturas en las cuales se registra la descomposición de carbohidratos (componentes de bajo peso molecular y polisacáridos (componentes de alto peso molecular fueron, respectivamente, de 284.51 °C y 470.42 °C; y para el almidón fueron de 307.51 °C y 500.46 °C. Los gránulos de almidón de banano tienen forma elipsoidal con un tamaño longitudinal promedio de 39.39 µm y tamaño transversal promedio de 29.47 µm. Los difractogramas de rayos X mostraron patrones de difracción tipo B. Los viscoamilogramas mostraron que para la harina la temperatura de inicio de gelatinización (Tg es de 76.3 °C, la viscosidad máxima de 1120 cP, y para el almidón la Tg fue de 70.75 °C y la viscosidad máxima de 2087 cP.

Effects of gamma irradiation followed by climatization on the quality of 'Prata' banana (Musa acuminata x Musa balbisiana, AAB)

Energy Technology Data Exchange (ETDEWEB)

Martineli, Maristella; Coneglian, Regina C.C.; Vasconcellos, Marco A.S.; Silva, Eduardo; Rocha, Janielio G.; Melo, Maruzanete P. [Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropedica, RJ. Inst. de Agronomia (Brazil)], e-mail: maristellamartineli@yahoo.com.br; Vital, Helio C. [Centro Tecnologico do Exercito (CTEx), Rio de Janeiro, RJ (Brazil). Secao de Defesa Nuclear], e-mail: vital@ctex.eb.br

2009-07-01

Banana is a highly perishable climacteric fruit. In order to ensure fast and homogeneous ripening that will make its processing and commercialization easier, it is usually treated by climatization. On the other hand, irradiation is an interesting physical process capable of delaying ripening and extending the shelf life of fruits. This work investigated the competing effects of irradiation followed by climatization on the quality of 'Prata' banana (Musa acuminata x Musa balbisiana, AAB). All fruits were harvested in the preclimacteric stage, rinsed and stored at 27 deg C after being submitted to five different treatments. After hygienization, four out of five samples were exposed to gamma-ray at doses of 0.25 and 0.50 kGy. The unirradiated fruits were left for control and half of the irradiated samples were then climatized by exposure to CaC{sub 2}. Measurements of fresh mass loss, total soluble solids, peel coloration and disease index were performed on five different dates for up to nine days in order to monitor quality and the degree of ripening. It was found that high temperatures prevailing during climatization and storage accelerated maturation in all fruits in spite of the use of irradiation, with the control becoming ripe in 3 days only. In addition, based on the consistent results from the experiments performed, it can be concluded that irradiation at the doses tested was unable to overcome the maturation effects produced by climatization. However, the sole use of irradiation with 0.25 kGy yielded the lowest figures for fresh mass loss and disease index in the samples, thus becoming the most attractive among the treatments tested. (author)

Development of partial life-cycle experiments to assess the effects of endocrine disruptors on the freshwater gastropod Lymnaea stagnalis: a case-study with vinclozolin.

Science.gov (United States)

Ducrot, Virginie; Teixeira-Alves, Mickaël; Lopes, Christelle; Delignette-Muller, Marie-Laure; Charles, Sandrine; Lagadic, Laurent

2010-10-01

Long-term effects of endocrine disruptors (EDs) on aquatic invertebrates remain difficult to assess, mainly due to the lack of appropriate sensitive toxicity test methods and relevant data analysis procedures. This study aimed at identifying windows of sensitivity to EDs along the life-cycle of the freshwater snail Lymnaea stagnalis, a candidate species for the development of forthcoming test guidelines. Juveniles, sub-adults, young adults and adults were exposed for 21 days to the fungicide vinclozolin (VZ). Survival, growth, onset of reproduction, fertility and fecundity were monitored weekly. Data were analyzed using standard statistical analysis procedures and mixed-effect models. No deleterious effect on survival and growth occurred in snails exposed to VZ at environmentally relevant concentrations. A significant impairment of the male function occurred in young adults, leading to infertility at concentrations exceeding 0.025 μg/L. Furthermore, fecundity was impaired in adults exposed to concentrations exceeding 25 μg/L. Biological responses depended on VZ concentration, exposure duration and on their interaction, leading to complex response patterns. The use of a standard statistical approach to analyze those data led to underestimation of VZ effects on reproduction, whereas effects could reliably be analyzed by mixed-effect models. L. stagnalis may be among the most sensitive invertebrate species to VZ, a 21-day reproduction test allowing the detection of deleterious effects at environmentally relevant concentrations of the fungicide. These results thus reinforce the relevance of L. stagnalis as a good candidate species for the development of guidelines devoted to the risk assessment of EDs.

Ripening of fruits of 'Dwarf Prata' banana (Musa acuminata x Musa balbisiana, AAB group)irradiated and treated with calcium carbide

International Nuclear Information System (INIS)

Martineli, Maristella; Coneglian, Regina C.C.; Vasconcellos, Marco A.S.; Silva, Eduardo; Vital, Helio C.

2011-01-01

The competing effects resulting from the exposure of fruits of 'warf prata' banana (Musa acuminata x Musa balbisiana, AAB group) to gamma radiation and to calcium carbide have been investigated in this work. The fruits were harvested in a pre-climateric stage (green colored though physiologically developed) in the city of Jaiba, state of Minas Gerais, and gamma irradiated with doses of 0.25 or 0.50 kGy in a research irradiating facility at the Brazilian Army Technology Center (CTEx) in the city of Rio de Janeiro. Some samples were also exposed to calcium carbide for 32 hours in order to accelerate ripening. Quantitative estimates of peel color, disease index and fresh mass loss were performed for 9 days while the fruits were kept at an average temperature of 23 deg C. The analyses were performed in the Federal Rural University of Rio de Janeiro, located in the city of Seropedica. The following treatments or combination of processes have been tested: untreated (control); treated only with irradiation with doses of 0.25 kGy or 0.50 kGy; treated with irradiation with doses of 0.25 kGy or 0.50 kGy and then exposed to calcium carbide. The fruits treated solely with irradiation with 0.25 kGy exhibited a better response during the first days of storage, although their initial green coloration vanished with time. In addition, the fungi Colletotrichum musae and Lasidioplodia theobroma were detected in samples submitted to the combination of both processes. In contrast, such fungi were not observed in fruits that had only been exposed to 0.25 kGy and exhibited low disease indices. Also, 1-2 cm lesions were detected on fruits.(author)

A Comparative Study of Liquid Nitrogen Cryotherapy as Monotherapy versus in Combination with Podophyllin in the Treatment of Condyloma Acuminata.

Science.gov (United States)

Sharma, Nidhi; Sharma, Sanjeev; Singhal, Chetna

2017-03-01

Condyloma Acuminata (CA) is a common viral sexually transmitted disease. Although various treatment modalities are available for treating CA, but none of them can achieve 100% response rate. In a search for better response rate and less recurrence rate, the combination of cytotoxic agent Podophyllin with ablative liquid nitrogen cryotherapy was evaluated over cryotherapy alone. To evaluate the synergistic effect of Podophyllin as a chemotherapeutic adjunct to an ablative therapy of liquid nitrogen cryotherapy versus liquid nitrogen cryotherapy alone in the treatment of CA. Sixty patients with multiple CA were randomly assigned to two groups in the study. Thirty patients in group A received double freeze thaw cycle of 25 seconds of liquid nitrogen cryotherapy. Thirty patients in Group B were subjected to liquid nitrogen cryotherapy in a similar manner followed by application of not more than 0.5 ml of 25% Podophyllin solution. All patients were followed up at 1, 4, 8, 12 and 24 weeks after the treatment to monitor the response to therapy and evaluation for any recurrence. When the number of unresponsive lesions were more than 30% of original lesions at 4 weeks follow-up, then the whole procedure was repeated again. The complete response rate and the recurrence rate in the Group B in our study were comparable to Group A as the difference was statistically insignificant. But the differentiating point was that the similar results were obtained in Group B with an average1.2 sessions per patient in comparison to an average of 1.67 sessions per patient in Group A. Cryotherapy represents a simple, safe and effective regimen for the treatment of multiple CA which in combination with Podophyllin is even more effective as a single session procedure; thereby shortening the treatment regimen.

Photo Degradation in Dye-Sensitized Solar Cells

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T. J. Abodunrin

2015-05-01

Full Text Available Mesoporous TiO2 of 20nm diameter is prepared in-tandem with organic dyes and based on Fluorine –doped SnO2 (FTO, conducting base is produced by hydrothermal process. The prepared mesoporous Cola Acuminata (C.acuminata, Lupinus Arboreus (L.arboreus and Bougainvillea Spectabilis (B.spectabilis films (0.16 cm2 are applied; individually and in combination as interfacial layer in-between nanocrystalline TiO2 (NC- TiO2 and the FTO anode in the dye-sensitized solar cell (DSSC. Absorbance index (A.I of all three dyes was studied within wavelength range 200-900 nm for a period of 11 months, equivalent to 352 sun exposure. C.acuminata had A.I value 4.00 that decreased to 2.32 under exposure to AM1.5 global conditions. B.spectabilis A.I was 1.19 but decreased to 0.520 within same period of study. Combination of C.acuminata and B.spectabilis gave A.I value 1.40, dye cocktails of C.acuminata, B.spectabilis and L.arboreus gave 2.00 A.I value for same wavelength range. A UV/Vis photo spectrometer was used to determine the prominent peaks and absorbance at such wavelengths. This exponential relationship is subject of our explorative study.

21 CFR 582.20 - Essential oils, oleoresins (solvent-free), and natural extractives (including distillates).

Science.gov (United States)

2010-04-01

.... Clover Trifolium spp. Coca (decocainized) Erythroxylum coca Lam. and other spp. of Erythroxylum. Coffee Coffea spp. Cola nut Cola acuminata Schott and Endl., and other spp. of Cola. Coriander Coriandrum... Cola acuminata Schott and Endl., and other spp. of Cola. Laurel berries Laurus nobilis L. Laurel leaves...

Activation of salicylic acid metabolism and signal transduction can enhance resistance to Fusarium wilt in banana (Musa acuminata L. AAA group, cv. Cavendish).

Science.gov (United States)

Wang, Zhuo; Jia, Caihong; Li, Jingyang; Huang, Suzhen; Xu, Biyu; Jin, Zhiqiang

2015-01-01

Fusarium wilt caused by the fungus Fusarium oxysporum f. sp. cubens (Foc) is the most serious disease that attacks banana plants. Salicylic acid (SA) can play a key role in plant-microbe interactions. Our study is the first to examine the role of SA in conferring resistance to Foc TR4 in banana (Musa acuminata L. AAA group, cv. Cavendish), which is the greatest commercial importance cultivar in Musa. We used quantitative real-time reverse polymerase chain reaction (qRT-PCR) to analyze the expression profiles of 45 genes related to SA biosynthesis and downstream signaling pathways in a susceptible banana cultivar (cv. Cavendish) and a resistant banana cultivar (cv. Nongke No. 1) inoculated with Foc TR4. The expression of genes involved in SA biosynthesis and downstream signaling pathways was suppressed in a susceptible cultivar and activated in a resistant cultivar. The SA levels in each treatment arm were measured using high-performance liquid chromatography. SA levels were decreased in the susceptible cultivar and increased in the resistant cultivar. Finally, we examined the contribution of exogenous SA to Foc TR4 resistance in susceptible banana plants. The expression of genes involved in SA biosynthesis and signal transduction pathways as well as SA levels were significantly increased. The results suggest that one reason for banana susceptibility to Foc TR4 is that expression of genes involved in SA biosynthesis and SA levels are suppressed and that the induced resistance observed in banana against Foc TR4 might be a case of salicylic acid-dependent systemic acquired resistance.

Morphological and molecular characterization of lymnaeid snails and their potential role in transmission of Fasciola spp. in Vietnam.

Science.gov (United States)

Dung, Bui Thi; Doanh, Pham Ngoc; The, Dang Tat; Loan, Ho Thi; Losson, Bertrand; Caron, Yannick

2013-12-01

Freshwater snails of the family Lymnaeidae play an important role in the transmission of fascioliasis worldwide. In Vietnam, 2 common lymnaeid species, Lymnaea swinhoei and Lymnaea viridis, can be recognized on the basis of morphology, and a third species, Lymnaea sp., is known to exist. Recent studies have raised controversy about their role in transmission of Fasciola spp. because of confusion in identification of the snail hosts. The aim of this study is, therefore, to clarify the identities of lymnaeid snails in Vietnam by a combination of morphological and molecular approaches. The molecular analyses using the second internal transcribed spacer (ITS2) of the nuclear ribosomal DNA clearly showed that lymnaeids in Vietnam include 3 species, Austropeplea viridis (morphologically identified as L. viridis), Radix auricularia (morphologically identified as L. swinhoei) and Radix rubiginosa (morphologically identified as Lymnaea sp.). R. rubiginosa is a new record for Vietnam. Among them, only A. viridis was found to be infected with Fasciola spp. These results provide a new insight into lymnaeid snails in Vietnam. Identification of lymnaeid snails in Vietnam and their role in the liver fluke transmission should be further investigated.

Estudo morfométrico da concha de Lymnaea columella say, 1817 (Mollusca, Gastropoda, Pulmonata

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Marlene T. Ueta

1980-12-01

Full Text Available Foram estudadas variações morfométricas de conchas de L. columella, provenientes de dez criadouros localizados nos seguintes municípios do Estado de São Paulo: - Campinas, Americana, Atibaia, Pirassununga, Caçapava e Taubaté. Foram analisados os diferentes tipos de ambientes onde as limneas são encontradas com maior freqüência, estabelecendo-se a época do ano com maior abundância em espécimes, que correspondeu aos meses de julho a outubro. As medidas nas conhas dos diferentes criadouros referiram-se ao comprimento e largura da concha, comprimento e largura da abertura, comprimento da espira e número de voltas. Foram estabelecidos os coeficientes de correlação e de regressão e realizadas análises de variância entre as medidas tomadas e os índices obtidos da relação entre largura/comprimento da concha. Estas conchas foram comparadas com as de L. columella, L. viator, L. cubensis da coleção do Museu Nacional do Rio de Janeiro. Para a maioria das medidas as conchas mostraram proporções constantes, embora apresentassem diferenças em relação ao desenvolvimento. A maior variação foi observada em relação ao comprimento da espira. As variações morfométricas das conchas foram relacionadas com alguns fatores externos como pH, alcalinidade, dureza e teor da água. Aparentemente apenas a dureza total da água influiu na consistência das conchas.Shells of Lymnaea columella from ten populations from the State of São Paulo were studied to determine morphometric variation. Samples were collected in the following municipalities: Campinas, Americana, Atibaia, Pirassununga, Caçapava and Taubaté. Five measurements were taken from each shell: length and width of the shell, length and width of the aperture and lenght of the spire. Two ratios were also established: width/lenght of the shell and length of the aperture /length of the shell. The numbers of whorls and the length of the shell were also determined. Statistical tests

Adaptation of Lymnaea fuscus and Radix balthica to Fasciola hepatica through the experimental infection of several successive snail generations

Science.gov (United States)

2014-01-01

Background High prevalence of Fasciola hepatica infection (>70%) was noted during several outbreaks before the 2000s in several French farms where Galba truncatula is lacking. Other lymnaeids such as Lymnaea fuscus, L. glabra and/or Radix balthica are living in meadows around these farms but only juvenile snails can sustain complete larval development of F. hepatica while older snails were resistant. The low prevalence of infection (<20%) and limited cercarial production (<50 cercariae per infected snail) noted with these juveniles could not explain the high values noted in these cattle herds. As paramphistomosis due to Calicophoron daubneyi was not still noted in these farms, the existence of another mode of infection was hypothesized. Experimental infection of several successive generations of L. glabra, originating from eggs laid by their parents already infected with this parasite resulted in a progressive increase in prevalence of snail infection and the number of shed cercariae. The aim of this paper was to determine if this mode of snail infection was specific to L. glabra, or it might occur in other lymnaeid species such as L. fuscus and R. balthica. Methods Five successive generations of L. fuscus and R. balthica were subjected to individual bimiracidial infections in the laboratory. Resulting rediae and cercariae in the first four generations were counted after snail dissection at day 50 p.e. (20°C), while the dynamics of cercarial shedding was followed in the F5 generation. Results In the first experiment, prevalence and intensity of F. hepatica infection in snails progressively increased from the F1 (R. balthica) or F2 (L. fuscus) generation. In the second experiment, the prevalence of F. hepatica infection and the number of shed cercariae were significantly lower in L. fuscus and R. balthica (without significant differences between both lymnaeids) than in G. truncatula. Conclusion The F. hepatica infection of several successive snail generations

Four year efficacy of prophylactic human papillomavirus quadrivalent vaccine against low grade cervical, vulvar, and vaginal intraepithelial neoplasia and anogenital warts: randomised controlled trial

DEFF Research Database (Denmark)

Dillner, Joakim; Kjaer, Susanne K; Wheeler, Cosette M

2010-01-01

To evaluate the prophylactic efficacy of the human papillomavirus (HPV) quadrivalent vaccine in preventing low grade cervical, vulvar, and vaginal intraepithelial neoplasias and anogenital warts (condyloma acuminata).......To evaluate the prophylactic efficacy of the human papillomavirus (HPV) quadrivalent vaccine in preventing low grade cervical, vulvar, and vaginal intraepithelial neoplasias and anogenital warts (condyloma acuminata)....

Identification and expression analysis of four 14-3-3 genes during fruit ripening in banana (Musa acuminata L. AAA group, cv. Brazilian).

Science.gov (United States)

Li, Mei-Ying; Xu, Bi-Yu; Liu, Ju-Hua; Yang, Xiao-Liang; Zhang, Jian-Bin; Jia, Cai-Hong; Ren, Li-Cheng; Jin, Zhi-Qiang

2012-02-01

To investigate the regulation of 14-3-3 proteins in banana (Musa acuminata L. AAA group, cv. Brazilian) fruit postharvest ripening, four cDNAs encoding 14-3-3 proteins were isolated from banana and designated as Ma-14-3-3a, Ma-14-3-3c, Ma-14-3-3e, and Ma-14-3-3i, respectively. Amino acid sequence alignment showed that the four 14-3-3 proteins shared a highly conserved core structure and variable C-terminal as well as N-terminal regions with 14-3-3 proteins from other plant species. Phylogenetic analysis revealed that the four 14-3-3 genes belong to the non-ε groups. They were differentially and specifically expressed in various tissues. Real-time RT-PCR analysis indicated that these four genes function differentially during banana fruit postharvest ripening. Three genes, Ma-14-3-3a, Ma-14-3-3c, and Ma-14-3-3e, were significantly induced by exogenous ethylene treatment. However, gene function differed in naturally ripened fruits. Ethylene could induce Ma-14-3-3c expression during postharvest ripening, but expression patterns of Ma-14-3-3a and Ma-14-3-3e suggest that these two genes appear to be involved in regulating ethylene biosynthesis during fruit ripening. No obvious relationship emerged between Ma-14-3-3i expression in naturally ripened and 1-MCP (1-methylcyclopropene)-treated fruit groups during fruit ripening. These results indicate that the 14-3-3 proteins might be involved in various regulatory processes of banana fruit ripening. Further studies will mainly focus on revealing the detailed biological mechanisms of these four 14-3-3 genes in regulating banana fruit postharvest ripening.

Ripening of fruits of 'Dwarf Prata' banana (Musa acuminata x Musa balbisiana, AAB group)irradiated and treated with calcium carbide

Energy Technology Data Exchange (ETDEWEB)

Martineli, Maristella [Instituto de Quimica. Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil); Coneglian, Regina C.C.; Vasconcellos, Marco A.S.; Silva, Eduardo, E-mail: rccconeg@ufrrj.br, E-mail: masv@ufrrj.br [Departamento de Fitotecnia. Instituto de Agronomia. Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropedica, RJ (Brazil); Vital, Helio C., E-mail: vital@ctex.eb.br [Secao de Defesa Nuclear. Divisao de Defesa Quimica, Biologica e Nuclear. Centro Tecnologico do Exercito (CTEx), Guaratiba, Rio de Janeiro, RJ (Brazil)

2011-07-01

The competing effects resulting from the exposure of fruits of 'warf prata' banana (Musa acuminata x Musa balbisiana, AAB group) to gamma radiation and to calcium carbide have been investigated in this work. The fruits were harvested in a pre-climateric stage (green colored though physiologically developed) in the city of Jaiba, state of Minas Gerais, and gamma irradiated with doses of 0.25 or 0.50 kGy in a research irradiating facility at the Brazilian Army Technology Center (CTEx) in the city of Rio de Janeiro. Some samples were also exposed to calcium carbide for 32 hours in order to accelerate ripening. Quantitative estimates of peel color, disease index and fresh mass loss were performed for 9 days while the fruits were kept at an average temperature of 23 deg C. The analyses were performed in the Federal Rural University of Rio de Janeiro, located in the city of Seropedica. The following treatments or combination of processes have been tested: untreated (control); treated only with irradiation with doses of 0.25 kGy or 0.50 kGy; treated with irradiation with doses of 0.25 kGy or 0.50 kGy and then exposed to calcium carbide. The fruits treated solely with irradiation with 0.25 kGy exhibited a better response during the first days of storage, although their initial green coloration vanished with time. In addition, the fungi Colletotrichum musae and Lasidioplodia theobroma were detected in samples submitted to the combination of both processes. In contrast, such fungi were not observed in fruits that had only been exposed to 0.25 kGy and exhibited low disease indices. Also, 1-2 cm lesions were detected on fruits.(author)

A homolog of the vertebrate pituitary adenylate cyclase-activating polypeptide is both necessary and instructive for the rapid formation of associative memory in an invertebrate

OpenAIRE

Pirger, Zsolt; László, Zita; Kemenes, Ildikó; Tóth, Gábor; Reglődi, Dóra; Kemenes, György

2010-01-01

Similar to other invertebrate and vertebrate animals, cAMP dependent signaling cascades are key components of long-term memory (LTM) formation in the snail Lymnaea stagnalis, an established experimental model for studying evolutionarily conserved molecular mechanisms of long-term associative memory. Although a great deal is already known about the signaling cascades activated by cAMP, the molecules involved in the learning-induced activation of adenylate cyclase (AC) in Lymnaea remained unkno...

Accumulation and detoxication responses of the gastropod Lymnaea stagnalis to single and combined exposures to natural (cyanobacteria) and anthropogenic (the herbicide RoundUp(®) Flash) stressors.

Science.gov (United States)

Lance, Emilie; Desprat, Julia; Holbech, Bente Frost; Gérard, Claudia; Bormans, Myriam; Lawton, Linda A; Edwards, Christine; Wiegand, Claudia

2016-08-01

Freshwater gastropods are increasingly exposed to multiple stressors in the field such as the herbicide glyphosate in Roundup formulations and cyanobacterial blooms either producing or not producing microcystins (MCs), potentially leading to interacting effects. Here, the responses of Lymnaea stagnalis to a 21-day exposure to non-MC or MC-producing (33μgL(-1)) Planktothrix agardhii alone or in combination with the commercial formulation RoundUp(®) Flash at a concentration of 1μgL(-1) glyphosate, followed by 14days of depuration, were studied via i) accumulation of free and bound MCs in tissues, and ii) activities of anti-oxidant (catalase CAT) and biotransformation (glutathione-S-transferase GST) enzymes. During the intoxication, the cyanobacterial exposure induced an early increase of CAT activity, independently of the MC content, probably related to the production of secondary cyanobacterial metabolites. The GST activity was induced by RoundUp(®) Flash alone or in combination with non MC-producing cyanobacteria, but was inhibited by MC-producing cyanobacteria with or without RoundUp(®) Flash. Moreover, MC accumulation in L. stagnalis was 3.2 times increased when snails were concomitantly exposed to MC-producing cyanobacteria with RoundUp(®), suggesting interacting effects of MCs on biotransformation processes. The potent inhibition of detoxication systems by MCs and RoundUp(®) Flash was reversible during the depuration, during which CAT and GST activities were significantly higher in snails previously exposed to MC-producing cyanobacteria with or without RoundUp(®) Flash than in other conditions, probably related to the oxidative stress caused by accumulated MCs remaining in tissues. Copyright © 2016 Elsevier B.V. All rights reserved.

Efecto del medio de soporte en la estabilidad biológica de dos cepas de Frankia aisladas de Alnus acuminata H. B. K.

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Ana María Rey

Full Text Available Alnus acuminata H. B. K. es una especie arbórea que puede ser incorporada en sistemas silvopastoriles, ya que tiene la capacidad de crecer en suelos marginados y contribuir a la conservación de la biodiversidad y al mejoramiento del suelo; lo cual se relaciona con la incorporación de hojarasca, el efecto de sombra, la retención de humedad, el reciclaje de nutrientes y la fijación de nitrógeno atmosférico, debido a su asociación simbiótica con el actinomiceto Frankia. La utilización de este como inoculante es una tecnología que requiere un profundo análisis de su comportamiento en condiciones controladas. Por otra parte, para la comercialización de los biofertilizantes es importante conservar su calidad el mayor tiempo posible, de lo cual depende la aceptación del producto en la cadena productiva. Por ello, se realizó una investigación con el objetivo de evaluar la estabilidad biológica de las cepas nativas de Frankia (Aan17 y Aac49 con diferentes proporciones sustrato:cepa, así como el efecto del alamacenamiento a 4 °C. Las cepas fueron tolerantes a los cambios del pH y al almacenamiento en condiciones de refrigeración. Se concluye que los inoculantes se deben almacenar a 4 °C durante 120 días, con una proporción de 80:20 (inoculante:sustrato en Aan17 y 60:40 en Aac49. En estos sustratos la proteína microbial se mantuvo por encima de 0,65 mg/mL en Aan17 y 0,7 mg/mL en Aac49.

Effects of chronic waterborne nickel exposure on growth, ion homeostasis, acid-base balance, and nickel uptake in the freshwater pulmonate snail, Lymnaea stagnalis.

Science.gov (United States)

Niyogi, Som; Brix, Kevin V; Grosell, Martin

2014-05-01

The freshwater pulmonate snail, Lymnaea stagnalis, is the most sensitive aquatic organism tested to date for Ni. We undertook a series of experiments to investigate the underlying mechanism(s) for this observed hypersensitivity. Consistent with previous experiments, juvenile snail growth in a 21-day exposure was reduced by 48% relative to the control when exposed to 1.3 μg l(-1) Ni (EC20 less than the lowest concentration tested). Ca(2+) homeostasis was significantly disrupted by Ni exposure as demonstrated by reductions in net Ca(2+) uptake, and reductions in Ca(2+) concentrations in the hemolymph and soft tissues. We also observed reduced soft tissue [Mg(2+)]. Snails underwent a significant alkalosis with hemolymph pH increasing from 8.1 to 8.3 and hemolymph TCO2 increasing from 19 to 22 mM in control versus Ni-exposed snails, respectively. Unlike in previous studies with Co and Pb, snail feeding rates were found to be unaffected by Ni at the end of the exposure. Snails accumulated Ni in the soft tissue in a concentration-dependent manner, and Ni uptake experiments with (63)Ni revealed a biphasic uptake profile - a saturable high affinity component at low exposure concentrations (36-189 nM) and a linear component at the high exposure concentrations (189-1,897 nM). The high affinity transport system had an apparent Km of 89 nM Ni(2+) and Vmax of 2.4 nmol g(-1)h(-1). This equates to a logK of 7.1, significantly higher than logK's (2.6-5.2) for any other aquatic organisms evaluated to date, which will have implications for Biotic Ligand Model development. Finally, pharmacological inhibitors that block Ca(2+) uptake pathways in snails did not inhibit Ni uptake, suggesting that the uptake of Ni does not occur via Ca(2+) uptake pathways. As with Cu and Pb, the exact mechanism for the significant disruption in Ca(2+) homeostasis and reduction in juvenile snail growth remains unknown. Copyright © 2014 Elsevier B.V. All rights reserved.

Phenylphenalenones Accumulate in Plant Tissues of Two Banana Cultivars in Response to Herbivory by the Banana Weevil and Banana Stem Weevil

OpenAIRE

H?lscher, Dirk; Buerkert, Andreas; Schneider, Bernd

2016-01-01

Phenylphenalenone-type compounds accumulated in the tissues of two banana cultivars—Musa acuminata cv. “Grande Naine” (AAA) and Musa acuminata × balbisiana Colla cv. “Bluggoe” (ABB)—when these were fed on by the banana weevil (Cosmopolites sordidus (Germ.) (Coleoptera: Curculionidae)) and the banana stem weevil (Odoiporus longicollis (Oliver) (Coleoptera: Curculionidae)). The chemical constituents of the banana material were separated by means of chromatographic techniques and identified by N...

Evasion of short interfering RNA-directed antiviral silencing in Musa acuminata persistently infected with six distinct banana streak pararetroviruses.

Science.gov (United States)

Rajeswaran, Rajendran; Seguin, Jonathan; Chabannes, Matthieu; Duroy, Pierre-Olivier; Laboureau, Nathalie; Farinelli, Laurent; Iskra-Caruana, Marie-Line; Pooggin, Mikhail M

2014-10-01

Vegetatively propagated crop plants often suffer from infections with persistent RNA and DNA viruses. Such viruses appear to evade the plant defenses that normally restrict viral replication and spread. The major antiviral defense mechanism is based on RNA silencing generating viral short interfering RNAs (siRNAs) that can potentially repress viral genes posttranscriptionally through RNA cleavage and transcriptionally through DNA cytosine methylation. Here we examined the RNA silencing machinery of banana plants persistently infected with six pararetroviruses after many years of vegetative propagation. Using deep sequencing, we reconstructed consensus master genomes of the viruses and characterized virus-derived and endogenous small RNAs. Consistent with the presence of endogenous siRNAs that can potentially establish and maintain DNA methylation, the banana genomic DNA was extensively methylated in both healthy and virus-infected plants. A novel class of abundant 20-nucleotide (nt) endogenous small RNAs with 5'-terminal guanosine was identified. In all virus-infected plants, 21- to 24-nt viral siRNAs accumulated at relatively high levels (up to 22% of the total small RNA population) and covered the entire circular viral DNA genomes in both orientations. The hotspots of 21-nt and 22-nt siRNAs occurred within open reading frame (ORF) I and II and the 5' portion of ORF III, while 24-nt siRNAs were more evenly distributed along the viral genome. Despite the presence of abundant viral siRNAs of different size classes, the viral DNA was largely free of cytosine methylation. Thus, the virus is able to evade siRNA-directed DNA methylation and thereby avoid transcriptional silencing. This evasion of silencing likely contributes to the persistence of pararetroviruses in banana plants. We report that DNA pararetroviruses in Musa acuminata banana plants are able to evade DNA cytosine methylation and transcriptional gene silencing, despite being targeted by the host silencing

Identification, transcriptional and functional analysis of heat-shock protein 90s in banana (Musa acuminata L.) highlight their novel role in melatonin-mediated plant response to Fusarium wilt.

Science.gov (United States)

Wei, Yunxie; Hu, Wei; Wang, Qiannan; Zeng, Hongqiu; Li, Xiaolin; Yan, Yu; Reiter, Russel J; He, Chaozu; Shi, Haitao

2017-01-01

As one popular fresh fruit, banana (Musa acuminata) is cultivated in the world's subtropical and tropical areas. In recent years, pathogen Fusarium oxysporum f. sp. cubense (Foc) has been widely and rapidly spread to banana cultivated areas, causing substantial yield loss. However, the molecular mechanism of banana response to Foc remains unclear, and functional identification of disease-related genes is also very limited. In this study, nine 90 kDa heat-shock proteins (HSP90s) were genomewide identified. Moreover, the expression profile of them in different organs, developmental stages, and in response to abiotic and fungal pathogen Foc were systematically analyzed. Notably, we found that the transcripts of 9 MaHSP90s were commonly regulated by melatonin (N-acetyl-5-methoxytryptamine) and Foc infection. Further studies showed that exogenous application of melatonin improved banana resistance to Fusarium wilt, but the effect was lost when cotreated with HSP90 inhibitor (geldanamycin, GDA). Moreover, melatonin and GDA had opposite effect on auxin level in response to Foc4, while melatonin and GDA cotreated plants had no significant effect, suggesting the involvement of MaHSP90s in the cross talk of melatonin and auxin in response to fungal infection. Taken together, this study demonstrated that MaHSP90s are essential for melatonin-mediated plant response to Fusarium wilt, which extends our understanding the putative roles of MaHSP90s as well as melatonin in the biological control of banana Fusarium wilt. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

DArT whole genome profiling provides insights on the evolution and taxonomy of edible Banana (Musa spp.)

Czech Academy of Sciences Publication Activity Database

Sardos, J.; Perrier, X.; Doležel, Jaroslav; Hřibová, Eva; Christelová, Pavla; Van den Houwe, I.; Kilian, A.; Roux, N.

2016-01-01

Roč. 118, č. 7 (2016), s. 1269-1278 ISSN 0305-7364 R&D Projects: GA MŠk(CZ) LO1204; GA MŠk LG15017 Institutional support: RVO:61389030 Keywords : multilocus genotype data * arrays technology dart * genetic diversity * population-structure * balbisiana colla * acuminata colla * markers * identification * aflp * domestication * Musa acuminata * Musa balbisiana * Musa spp. * banana * DArT * domestication * taxonomy * classification * domestication Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Plant sciences, botany Impact factor: 4.041, year: 2016

Chemical Composition and Biological Activities of the Essential Oils from Three Melaleuca Species Grown in Tunisia

Directory of Open Access Journals (Sweden)

Ismail Amri

2012-12-01

Full Text Available The chemical composition of the essential oils of Melaleuca armillaris Sm., Melaleuca styphelioides Sm. and Melaleuca acuminata F. Muell., collected in Tunisia, was studied by means of GC and GC-MS analysis. In all, 46 compounds were identified, 38 for M. armillaris, 20 for M. acuminata and eight for M. styphelioides, respectively. The presence of a sesquiterpenic fraction (52.2% characterized the oil from M. armillaris; M. sthypheliodes oil was rich in methyl eugenol, a phenolic compound (91.1%, while M. acuminata oil is mainly constituted by oxygenated monoterpenoids (95.6%. The essential oils were evaluated for their in vitro potentially phytotoxic activity against germination and initial radicle growth of Raphanus sativus L., Lepidium sativum L., Sinapis arvensis L., Triticum durum L. and Phalaris canariensis L. seeds. The radicle elongation of five seeds was inhibited at the highest doses tested, while germination of all seeds was not affected. Moreover, the essential oils showed low antimicrobial activity against eight selected microorganisms.

Chemical composition and biological activities of the essential oils from three Melaleuca species grown in Tunisia.

Science.gov (United States)

Amri, Ismail; Mancini, Emilia; De Martino, Laura; Marandino, Aurelio; Lamia, Hamrouni; Mohsen, Hanana; Bassem, Jamoussi; Scognamiglio, Mariarosa; Reverchon, Ernesto; De Feo, Vincenzo

2012-12-05

The chemical composition of the essential oils of Melaleuca armillaris Sm., Melaleuca styphelioides Sm. and Melaleuca acuminata F. Muell., collected in Tunisia, was studied by means of GC and GC-MS analysis. In all, 46 compounds were identified, 38 for M. armillaris, 20 for M. acuminata and eight for M. styphelioides, respectively. The presence of a sesquiterpenic fraction (52.2%) characterized the oil from M. armillaris; M. sthypheliodes oil was rich in methyl eugenol, a phenolic compound (91.1%), while M. acuminata oil is mainly constituted by oxygenated monoterpenoids (95.6%). The essential oils were evaluated for their in vitro potentially phytotoxic activity against germination and initial radicle growth of Raphanus sativus L., Lepidium sativum L., Sinapis arvensis L., Triticum durum L. and Phalaris canariensis L. seeds. The radicle elongation of five seeds was inhibited at the highest doses tested, while germination of all seeds was not affected. Moreover, the essential oils showed low antimicrobial activity against eight selected microorganisms.

Impact of the redox-cycling herbicide diquat on transcript expression and antioxidant enzymatic activities of the freshwater snail Lymnaea stagnalis

Energy Technology Data Exchange (ETDEWEB)

Bouetard, Anthony, E-mail: anthony.bouetard@rennes.inra.fr [INRA, UMR INRA-Agrocampus Ouest ESE 0985, Equipe Ecotoxicologie et Qualite des Milieux Aquatiques, 65 rue de Saint-Brieuc, 35042 Rennes cedex (France); Besnard, Anne-Laure; Vassaux, Daniele; Lagadic, Laurent; Coutellec, Marie-Agnes [INRA, UMR INRA-Agrocampus Ouest ESE 0985, Equipe Ecotoxicologie et Qualite des Milieux Aquatiques, 65 rue de Saint-Brieuc, 35042 Rennes cedex (France)

2013-01-15

The presence of pesticides in the environment results in potential unwanted effects on non-target species. Freshwater organisms inhabiting water bodies adjacent to agricultural areas, such as ditches, ponds and marshes, are good models to test such effects as various pesticides may reach these habitats through several ways, including aerial drift, run-off, and drainage. Diquat is a non-selective herbicide used for crop protection or for weed control in such water bodies. In this study, we investigated the effects of diquat on a widely spread aquatic invertebrate, the holarctic freshwater snail Lymnaea stagnalis. Due to the known redox-cycling properties of diquat, we studied transcript expression and enzymatic activities relative to oxidative and general stress in the haemolymph and gonado-digestive complex (GDC). As diquat is not persistent, snails were exposed for short times (5, 24, and 48 h) to ecologically relevant concentrations (22.2, 44.4, and 222.2 {mu}g l{sup -1}) of diquat dibromide. RT-qPCR was used to quantify the transcription of genes encoding catalase (cat), a cytosolic superoxide dismutase (Cu/Zn-sod), a selenium-dependent glutathione peroxidase (gpx), a glutathione reductase (gred), the retinoid X receptor (rxr), two heat shock proteins (hsp40 and hsp70), cortactin (cor) and the two ribosomal genes r18S and r28s. Enzymatic activities of SOD, Gpx, Gred and glutathione S-transferase (GST) were investigated in the GDC using spectrophoto/fluorometric methods. Opposite trends were obtained in the haemolymph depending on the herbicide concentration. At the lowest concentration, effects were mainly observed after 24 h of exposure, with over-transcription of cor, hsp40, rxr, and sod, whereas higher concentrations down-regulated the expression of most of the studied transcripts, especially after 48 h of exposure. In the GDC, earlier responses were observed and the fold-change magnitude was generally much higher: transcription of all target genes increased

Forestiera acuminata (Michx.)

Science.gov (United States)

K.F. Connor

2004-01-01

Swamp privet is a deciduous shrub or small, open-crowned tree, occasionally reaching 10 m in height but more often averaging 1.5 to 2.5 m. It is commonly multi-trunked. The bark ranges from gray to dark brown in color and is either smooth or ridged. Twigs are light brown, glabrous, and have conspicuous lenticels. Leaves are simple, opposite, and a dull, yellowish green...

Protein (Cyanobacteria): 383945 [PGDBj - Ortholog DB

Lifescience Database Archive (English)

Full Text Available ckel incorporation protein HypA Oscillatoria acuminata PCC 6304 MHEVSLMENTLNIALDCASAQNASKIHRLKMRVGDLSGVVPDALEFAFDVVTRGTIAEGAKFEIERVPVVCHCSTCDRNFEPIDLFYECPHCHQLTYQIQSGQEIELTSLEVS ...

A homolog of the vertebrate pituitary adenylate cyclase-activating polypeptide is both necessary and instructive for the rapid formation of associative memory in an invertebrate.

Science.gov (United States)

Pirger, Zsolt; László, Zita; Kemenes, Ildikó; Tóth, Gábor; Reglodi, Dóra; Kemenes, György

2010-10-13

Similar to other invertebrate and vertebrate animals, cAMP-dependent signaling cascades are key components of long-term memory (LTM) formation in the snail Lymnaea stagnalis, an established experimental model for studying evolutionarily conserved molecular mechanisms of long-term associative memory. Although a great deal is already known about the signaling cascades activated by cAMP, the molecules involved in the learning-induced activation of adenylate cyclase (AC) in Lymnaea remained unknown. Using matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy in combination with biochemical and immunohistochemical methods, recently we have obtained evidence for the existence of a Lymnaea homolog of the vertebrate pituitary adenylate cyclase-activating polypeptide (PACAP) and for the AC-activating effect of PACAP in the Lymnaea nervous system. Here we first tested the hypothesis that PACAP plays an important role in the formation of robust LTM after single-trial classical food-reward conditioning. Application of the PACAP receptor antagonist PACAP6-38 around the time of single-trial training with amyl acetate and sucrose blocked associative LTM, suggesting that in this "strong" food-reward conditioning paradigm the activation of AC by PACAP was necessary for LTM to form. We found that in a "weak" multitrial food-reward conditioning paradigm, lip touch paired with sucrose, memory formation was also dependent on PACAP. Significantly, systemic application of PACAP at the beginning of multitrial tactile conditioning accelerated the formation of transcription-dependent memory. Our findings provide the first evidence to show that in the same nervous system PACAP is both necessary and instructive for fast and robust memory formation after reward classical conditioning.

Morphological, molecular and ecological aspects of the South American hypogeous fungus Alpova austroalnicola sp. nov.

Science.gov (United States)

Nouhra, Eduardo R; Dominguez, Laura S; Becerra, Alejandra G; Trappe, James M

2005-01-01

Field studies in Argentina's Yunga District revealed Alpova austroalnicola sp. nov., a hypogeous fungus associated with Alnus acuminata ssp. acuminata. Morphological and molecular studies based on amplification and sequencing of the nuclear LSU rDNA gene showed its unique identity within Alpova. Related genera included in the analyses were Boletus edulis, Rhizopogon spp., Suillus luteus and Truncocolumella citrina. Additional observations of animal diggings around the sites and microscopic examination of fecal pellets of the nine-banded armadillo (Dasypus novemcinctus novemcinctus) indicate A. austroalnicola is consumed and its spores dispersed by animals.

Acantholytic dermatosis of the crural folds with ATP2C1 mutation is a possible variant of Hailey-Hailey Disease.

Science.gov (United States)

Lipoff, Jules B; Mudgil, Adarsh V; Young, Saryna; Chu, Paul; Cohen, Steven R

2009-01-01

We describe a patient with acantholytic dermatosis of the crural folds (ADCF) that was misdiagnosed and treated as condyloma acuminata for 13 years. After many skin biopsies consistently showed epidermal acantholysis and negative human papillomavirus serotyping excluded condyloma acuminata, a diagnosis of ADCF was considered most likely. Acitretin effectively suppressed the symptomatic hyperkeratosis. Subsequent genetic testing revealed a deletion in the ATP2C1 gene that led us to conclude that this case of ADCF is probably a variant of familial benign chronic pemphigus (Hailey-Hailey disease).

Phenylphenalenones Accumulate in Plant Tissues of Two Banana Cultivars in Response to Herbivory by the Banana Weevil and Banana Stem Weevil.

Science.gov (United States)

Hölscher, Dirk; Buerkert, Andreas; Schneider, Bernd

2016-08-25

Phenylphenalenone-type compounds accumulated in the tissues of two banana cultivars-Musa acuminata cv. "Grande Naine" (AAA) and Musa acuminata × balbisiana Colla cv. "Bluggoe" (ABB)-when these were fed on by the banana weevil (Cosmopolites sordidus (Germ.) (Coleoptera: Curculionidae)) and the banana stem weevil (Odoiporus longicollis (Oliver) (Coleoptera: Curculionidae)). The chemical constituents of the banana material were separated by means of chromatographic techniques and identified by NMR spectroscopy. One new compound, 2-methoxy-4-phenylphenalen-1-one, was found exclusively in the corm material of "Bluggoe" that had been fed on by the weevils.

Kamptotesin

OpenAIRE

Kurtan, Merve; Kurtoğlu, Sezin; Melikoğlu, Gülay

2014-01-01

Monoterpen indol alkaloit olan kamptotesin ilk olarak 1957’deÇin’de bulunan Camptotheca acuminata Decaisne türünden eldeedilmiştir. Kamptotesin sadece C. acuminata (Nyssaceae)bitkisinde değil Icacinaceae, Rubiaceae, Loganiaceae veApocynaceae gibi çeşitli familyalara ait başka bitkilerde debulunmuştur. Bu çalışma, kamptotesin ve kamptotesin türevlerininbitkiler alemindeki dağılımı ile ilgili ayrıntılı bir değerlendirmesağlamaktadır. Antitümör alkaloit olarak bilinen kamptotesin DNAtopoizomeraz...

Phenylphenalenones Accumulate in Plant Tissues of Two Banana Cultivars in Response to Herbivory by the Banana Weevil and Banana Stem Weevil

Directory of Open Access Journals (Sweden)

Dirk Hölscher

2016-08-01

Full Text Available Phenylphenalenone-type compounds accumulated in the tissues of two banana cultivars—Musa acuminata cv. “Grande Naine” (AAA and Musa acuminata × balbisiana Colla cv. “Bluggoe” (ABB—when these were fed on by the banana weevil (Cosmopolites sordidus (Germ. (Coleoptera: Curculionidae and the banana stem weevil (Odoiporus longicollis (Oliver (Coleoptera: Curculionidae. The chemical constituents of the banana material were separated by means of chromatographic techniques and identified by NMR spectroscopy. One new compound, 2-methoxy-4-phenylphenalen-1-one, was found exclusively in the corm material of “Bluggoe” that had been fed on by the weevils.

Canadian Association of Neurosciences Review: learning at a snail's pace.

Science.gov (United States)

Parvez, Kashif; Rosenegger, David; Martens, Kara; Orr, Michael; Lukowiak, Ken

2006-11-01

While learning and memory are related, they are distinct processes each with different forms of expression and underlying molecular mechanisms. An invertebrate model system, Lymnaea stagnalis, is used to study memory formation of a non-declarative memory. We have done so because: (1) We have discovered the neural circuit that mediates an interesting and tractable behaviour; (2) This behaviour can be operantly conditioned and intermediate-term and long-term memory can be demonstrated; and (3) It is possible to demonstrate that a single neuron in the model system is a necessary site of memory formation. This article reviews how Lymnaea has been used in the study of behavioural and molecular mechanisms underlying consolidation, reconsolidation, extinction and forgetting.

High efficiency transformation of banana [Musa acuminata L. cv. Matti (AA)] for enhanced tolerance to salt and drought stress through overexpression of a peanut salinity-induced pathogenesis-related class 10 protein.

Science.gov (United States)

Rustagi, Anjana; Jain, Shalu; Kumar, Deepak; Shekhar, Shashi; Jain, Mukesh; Bhat, Vishnu; Sarin, Neera Bhalla

2015-01-01

Bananas and plantains (Musa spp. L.) are important subsistence crops and premium export commodity in several countries, and susceptible to a wide range of environmental and biotic stress conditions. Here, we report efficient, rapid, and reproducible Agrobacterium-mediated transformation and regeneration of an Indian niche cultivar of banana [M. acuminata cv. Matti (AA)]. Apical meristem-derived highly proliferative multiple shoot clump (MSC) explants were transformed with the Agrobacterium strain EHA105 harboring a binary vector pCAMBIA-1301 carrying hptII and uidA. Sequential agro-infiltration (10 min, 400 mmHg), infection (additional 35 min, Agrobacterium density A 600 = 0.8) and co-cultivation (18 h) regimen in 100 µM acetosyringone containing liquid medium were critical factors yielding high transformation efficiency (~81 %) corroborated by transient GUS expression assay. Stable transgenic events were recovered following two cycles of meristem initiation and selection on hygromycin containing medium. Histochemical GUS assay in several tissues of transgenic plants and molecular analyses confirmed stable integration and expression of transgene. The protocol described here allowed recovery of well-established putative transgenic plantlets in as little as 5 months. The transgenic banana plants could be readily acclimatized under greenhouse conditions, and were phenotypically similar to the wild-type untransformed control plants (WT). Transgenic plants overexpressing Salinity-Induced Pathogenesis-Related class 10 protein gene from Arachis hypogaea (AhSIPR10) in banana cv. Matti (AA) showed better photosynthetic efficiency and less membrane damage (P < 0.05) in the presence of NaCl and mannitol in comparison to WT plants suggesting the role of AhSIPR10 in better tolerance of salt stress and drought conditions.

Molecular characterisation of Galba truncatula, Lymnaea neotropica and L. schirazensis from Cajamarca, Peru and their potential role in transmission of human and animal fascioliasis.

Science.gov (United States)

Bargues, M Dolores; Artigas, Patricio; Khoubbane, Messaoud; Ortiz, Pedro; Naquira, Cesar; Mas-Coma, Santiago

2012-08-15

Human and animal fascioliasis is emerging in many world regions, among which Andean countries constitute the largest regional hot spot and Peru the country presenting more human endemic areas. A survey was undertaken on the lymnaeid snails inhabiting the hyperendemic area of Cajamarca, where human prevalences are the highest known among the areas presenting a "valley transmission pattern", to establish which species are present, genetically characterise their populations by comparison with other human endemic areas, and discuss which ones have transmission capacity and their potential implications with human and animal infection. Therefore, ribosomal DNA ITS-2 and ITS-1, and mitochondrial DNA 16S and cox1 were sequenced by the dideoxy chain-termination method. Results indicate the presence of three, morphologically similar, small lymnaeid species belonging to the Galba/Fossaria group: Galba truncatula, Lymnaea neotropica and L. schirazensis. Only one combined haplotype for each species was found. The ITS-1, 16S and cox1 haplotypes of G. truncatula are new. No new haplotypes were found in the other two species. This scenario changes previous knowledge, in which only L. viator (= L. viatrix) was mentioned. Galba truncatula appears to be the most abundant, with high population densities and evident anthropophyly including usual presence in human neighbourhood. Infection by Fasciola hepatica larval stages were molecularly confirmed in two populations of this species. The nearness between G. truncatula populations presenting liver fluke infection and both human settings and schools for children, together with the absence of populations of other lymnaeid species in the locality, suggest a direct relationship with human infection. The geographical overlap of three lymnaeid species poses problems for epidemiological studies and control action. First, a problem in classifying lymnaeid specimens in both field and laboratory activities, given their transmission capacity

Seasonal variability of Dinophysis spp. and Protoceratium reticulatum associated to lipophilic shellfish toxins in a strongly stratified Chilean fjord

Science.gov (United States)

Alves-de-Souza, Catharina; Varela, Daniel; Contreras, Cristóbal; de La Iglesia, Pablo; Fernández, Pamela; Hipp, Byron; Hernández, Cristina; Riobó, Pilar; Reguera, Beatriz; Franco, José M.; Diogène, Jorge; García, Carlos; Lagos, Néstor

2014-03-01

The fine scale vertical distribution of Dinophysis spp. and Protoceratium reticulatum (potential producers of lipophilic shellfish toxins, LSTs) and its relation with LSTs in shellfish was studied in Reloncaví fjord, a strongly stratified system in Southern Chile. Samples were taken over two years from late spring to early autumn (2007-2008 period) and from early spring to late summer (2008-2009 period). Dinophysis spp., in particular Dinophysis acuminata, were always detected, often forming thin layers in the region of the salinity driven pycnocline, with cell maxima for D. acuminata of 28.5×103 cells L-1 in March 2008 and 17.1×103 cells L-1 in November 2008. During the 2008-2009 sampling period, blooms of D. acuminata co-occurred with high densities of cryptophyceans and the ciliate Mesodinium spp. The highest levels of pectenotoxin-2 (PTX-2; 2.2 ng L-1) were found in the plankton in February 2009, associated with moderate densities of D. acuminata, Dinophysis tripos and Dinophysis subcircularis (0.1-0.6×103 cells L-1). However, only trace levels of PTX-2 were observed in bivalves at that time. Dinophysistoxin (DTX-1 and DTX-3) levels in bivalves and densities of Dinophysis spp. were not well correlated. Low DTX levels in bivalves observed during a major bloom of D. acuminata in March 2008 suggested that there is a large seasonal intraspecific variability in toxin content of Dinophysis spp. driven by changes in population structure associated with distinct LST toxin profiles in Reloncaví fjord during the study period. A heterogeneous vertical distribution was also observed for P. reticulatum, whose presence was restricted to summer months. A bloom of this species of 2.2×103 cells L-1 at 14 m depth in February 2009 was positively correlated with high concentrations of yessotoxins in bivalves (51-496 ng g-1) and plankton samples (3.2 ng L-1). Our results suggest that a review of monitoring strategies for Dinophysis spp. in strongly stratified fjord systems

Headspace Analysis of Volatile Compounds Coupled to Chemometrics in Leaves from the Magnoliaceae Family

Directory of Open Access Journals (Sweden)

Mohamed A. Farag

2015-01-01

Full Text Available Headspace volatile analysis has been used for volatiles profiling in leaves of 4 Magnolia species with a total of 75 compounds were identified. Monterpene hydrocarbons dominated the volatile blend of M. calophylla (86%, M. acuminata (78%, M. virginiana (70% and M. grandiflora (47% with b -pinene and b -ocimene occurring in the largest amounts, whereas sesquiterpenes were the most abundant compounds in M. grandiflora (39%. High levels of oxygenated compounds were only found in M. virginiana volatile blend (11.4% with 2-phenylethyl alcohol as major component. Hierarchical cluster analysis performed on volatiles content revealed the close relationship between M. acuminata and M. calophylla.

The effect of ammonium chloride concentrationson the content of carotenoid pigments in the body of Lymnaea stagnalis

Directory of Open Access Journals (Sweden)

G. E. Kyrychuk

2015-09-01

Full Text Available The paper deals with the peculiarities of distribution of β-carotene and xanthophylls in the body of Lymnaea stagnalis (Linnaeus, 1758 (Pulmonata, Lymnaeidae in the normal conditions and under the action of different concentrations of NH4Cl, depending on duration of exposure (2, 7, 14 and 21 days. L. stagnalis (300 copies were collected in September 2013–2014 (in Zhytomyr region. Toxicant NH4Cl was used in concentrations corresponding to 0.5, 2, 5 and 10 MAC. The content of β-carotene and xanthophylls was determined by the Taylor method. 2400 biochemical analyses were carried out. The article shows that under the action of 0.5 MPC NH4Cl adaptive processes are stimulated in the body of L. stagnalis and total antioxidant activity is activated, as evidenced by changes in the content of β-carotene and xanthophylls in the organs (hepatopancreas, pallium and foot and tissues (hemolymph of the mollusks under study. The research proves that the action of concentration discussed above during 2, 14 and 21 days causes the increase in the content of β-carotene in hepatopancreas (1.63–5.73 times, pallium (1.68–5.37 times and foot (1.81–3.89 times of animals. Incubation of mollusks in solutions of NH4Cl (0.5 MAC for 7 days resulted in the decrease of figures in these organs by 23,6–38,8% relatively to control. It should be noted that from the overall dynamics hemolymph is somewhat distracting; for it 1.35–1.46 times’ decrease in the content of β-carotene after short-term action of the toxicant (2 and 7 days and β-carotene increase by 2.79–7.38 times under conditions of prolonged exposure (14 and 21 days is recorded. The content of xanthophylls correlates with the content of β-carotene on the 2nd, 7th and 14th day of toxic action, but by increasing the time of contact with toxic substances to 21 days the decrease in figures by 20,9–40,7% in foot and pallium is recorded. When the toxicant concentration is increased to 2 MAC (with 2

Attachment study of Agrobacterium tumefaciens to yam spp

African Journals Online (AJOL)

Charles S.Wortmann

dodecandra) berries (Type 44) on different developmental stages of. Lymnaea ... flukicidal drugs and the use of molluscides to kill snail intermediate hosts are ... age groups of fasciola transmitting snails and assessing time-concentration.

Molecular characterisation of Galba truncatula, Lymnaea neotropica and L. schirazensis from Cajamarca, Peru and their potential role in transmission of human and animal fascioliasis

Science.gov (United States)

2012-01-01

Background Human and animal fascioliasis is emerging in many world regions, among which Andean countries constitute the largest regional hot spot and Peru the country presenting more human endemic areas. A survey was undertaken on the lymnaeid snails inhabiting the hyperendemic area of Cajamarca, where human prevalences are the highest known among the areas presenting a "valley transmission pattern", to establish which species are present, genetically characterise their populations by comparison with other human endemic areas, and discuss which ones have transmission capacity and their potential implications with human and animal infection. Methods Therefore, ribosomal DNA ITS-2 and ITS-1, and mitochondrial DNA 16S and cox1 were sequenced by the dideoxy chain-termination method. Results Results indicate the presence of three, morphologically similar, small lymnaeid species belonging to the Galba/Fossaria group: Galba truncatula, Lymnaea neotropica and L. schirazensis. Only one combined haplotype for each species was found. The ITS-1, 16S and cox1 haplotypes of G. truncatula are new. No new haplotypes were found in the other two species. This scenario changes previous knowledge, in which only L. viator (= L. viatrix) was mentioned. Galba truncatula appears to be the most abundant, with high population densities and evident anthropophyly including usual presence in human neighbourhood. Infection by Fasciola hepatica larval stages were molecularly confirmed in two populations of this species. The nearness between G. truncatula populations presenting liver fluke infection and both human settings and schools for children, together with the absence of populations of other lymnaeid species in the locality, suggest a direct relationship with human infection. Conclusions The geographical overlap of three lymnaeid species poses problems for epidemiological studies and control action. First, a problem in classifying lymnaeid specimens in both field and laboratory activities

Review of dermatology use of 5-aminolevulinic acid photodynamic therapy in China from 1997 to 2013

Science.gov (United States)

Wang, Peiru; Zhang, Guolong; Wang, Xiuli

2015-07-01

The prodrug 5-aminolevulinic acid (ALA) and its ester derivatives have been used in photodynamic therapy (PDT) in dermatology worldwide. In China, ALA-PDT was first used to treat urethral condylomata acuminata and non-melanoma skin cancers in 1997. A powder formulation of ALA hydrochloride was approved by the Chinese Food and Drug Administration for the treatment of condylomata acuminata in 2007. Large successful experience of treating condylomatas was accumulated compared with Western countries. Meanwhile, numerous clinical studies as well as off-label use of ALAPDT have been carried out in China. To reflect the progress of ALA-PDT in China, several major Chinese and English databases were searched and published data were reviewed in this article.

Four year efficacy of prophylactic human papillomavirus quadrivalent vaccine against low grade cervical, vulvar, and vaginal intraepithelial neoplasia and anogenital warts: randomised controlled trial

DEFF Research Database (Denmark)

Dillner, Joakim; Kjaer, Susanne K; Wheeler, Cosette M

2010-01-01

To evaluate the prophylactic efficacy of the human papillomavirus (HPV) quadrivalent vaccine in preventing low grade cervical, vulvar, and vaginal intraepithelial neoplasias and anogenital warts (condyloma acuminata)....

Protein (Cyanobacteria): 428211012 [PGDBj - Ortholog DB

Lifescience Database Archive (English)

Full Text Available YP_007084156.1 NC_019694 1117:23174 ... 1150:9233 1301283:90386 ... 1158:1065 118323:857 56110:857 ... hydroxylam...ine reductase Oscillatoria acuminata PCC 6304 MYCSQCEQTAGGEACYQWGACGKSPEVDALQDLLTHL

The suitability of several aquatic snails as intermediate hosts for Angiostrongylus cantonensis.

Science.gov (United States)

Yousif, F; Lämmler, G

1975-10-16

Sixteen species of aquatic snails of four families were tested by quantitative technique under standardized conditions for their suitability as intermediate hosts for Angiostrongylus cantonensis. These species were the planorbid snails Biomphalaria glabrata, Biomphalaria alexandrina, Planorbis planorbis, Planorbis intermixtus, Bulinus truncatus, Bulinus contortus, Bulinus africanus, Bulinus tropicus and Helisoma sp.; the lymnaeid snails Lymnaea natalensis, Lymnaea tomentosa, Lymnaea stagnalis, and Stagnicola elodes; the physid snail Physa acuta (an Egyptian and a German strain) and the ampullariid snails Marisa cornuarietis and Lanistes carinatus. All these snail species proved to be susceptible to infection with A. cantonensis, and first stage larvae reached the infective third stage in all of them. However, the rate and intensity of infection varied with different species. B. glabrata was the most susceptible snail species with a 100% infection rate and an average percentage recovery of third stage larvae of 26.1. This was followed by S. elodes and B. africanus, with a 100% infection rate and an average percentage recovery of third stage larvae of 15.6 and 14.6 respectively. The rest of snail species proved to be less susceptible. For comparative evaluation of the suitability of the various snail species as intermediate hosts of A. cantonensis a "Capacity Index" was determined. This index should provide a useful method for the evaluation of the suitability of various snails as intermediate hosts of nematode parasites under standardized conditions in the laboratory.

Charcoal anatomy of forest species

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Graciela Inés Bolzon de Muñiz1

2012-09-01

Full Text Available Vegetal charcoal retains the anatomical structure of the wood and may permit its botanical identification, which depends on species characteristics, the charcoal fragments size and preservation state. Anatomical characterization of ten forest species charcoal was done envisaging the identification and control of illegal charcoal. Differences between gymnosperms and angiosperms are evident in carbonized wood. Vessel diameter was statistically different between wood and charcoal in Vatairea guianensis, Mezilaurus itauba, Calophyllum brasiliense e Qualea cf. acuminata, and vessel frequency in Vatairea guianensis, Manilkara huberi, Qualea cf. acuminata e Simarouba amara. The anatomical structure from wood, in general aspects, is constant during carbonization process using temperature of 450°C, being possible to identify the material by using its cellular components.

EFECTO DE LA ADICIÓN DE CAL A PLANTACIONES DE JAÚL (Alnus acuminata EN ANDISOLES DE LA CUENCA ALTA DEL RÍO VIRILLA, COSTA RICA

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Marlon Salazar

2011-01-01

Full Text Available Con el propósito de evaluar el impacto de adicionar cal a plantaciones de jaúl (Alnus acuminata (H.B.K. O. Kuntze en Andisoles de la cuenca alta del río Virilla, Costa Rica, se realizó el presente trabajo en 2 localidades: 1 Finca Hospicio: Ubicada en la localidad de Vista de Mar, cantón de Goicoechea, a una altitud de 1542 msmn; el suelo se clasificó como Typic Udivitrands y la plantación se estableció en el 2002. 2 Finca Dorval: Ubicada en la localidad de Las Nubes, cantón de Vásquez de Coronado, a una altitud de 1925 msnm; el suelo se clasificó como Thaptic Udivitrands y la plantación se estableció en 1997. Los tratamientos aplicados fueron 0 (testigo, 750, 1500 y 2250 kg.ha-1 de carbonato de calcio y magnesio (Dolomita, 1500 kg.ha-1 de carbonato de calcio (Calcita y 1500 kg.ha-1 de sulfato de calcio (Yeso. Se midieron el diámetro a la altura del pecho (DAP a 1,3 m, la altura total de los árboles (m y se estimó el volumen (V mediante la formula: V(m3=2,71828¿10,0557+ln(d*2,0369+0,9277 18*ln(h propuesta por Segura et al. (2005, en la cual d es el DAP en cm y h es la altura total en m. Al comparar las mediciones del diámetro a la altura del pecho, incremento medio anual en diámetro (IMA-DAP, altura total, incremento medio anual en altura (IMA-ALT, volumen total e incremento en volumen total, por dosis y fuentes de cal aplicada, se observó que ningún tratamiento causó diferencias estadísticas, en estas variables en ninguna de las 2 fincas comparadas ni entre épocas de medición. La adición de fuentes y niveles de cal no afectó significativamente las variables diámetro, altura y volumen. La falta de respuesta a las diferentes enmiendas comparadas demuestra que el suelo proporcionó suficiente Ca, Mg y S para asegurar el crecimiento óptimo del jaúl. Tampoco se encontró que los suelos mostraran problemas de acidez de magnitud tal que afectaran negativamente el crecimiento del jaúl.

Effects of hot-water extract of banana (Musa acuminata) fruit's peel on the antibacterial activity, and anti-hypothermal stress, immune responses and disease resistance of the giant freshwater prawn, Macrobrachium rosenbegii.

Science.gov (United States)

Rattanavichai, Wutti; Cheng, Winton

2014-08-01

The hot-extracts isolated from fruit's peel of banana, Musa acuminata, was evaluated on the antibacterial activity to pathogens from aquatic animals, and immunostimulating potential, disease resistance and anti-hypothermal stress in giant freshwater prawn, Macrobrachium rosenbergii through injection administration. The banana peel extract (BPE) showed good activity against 1 Gram-positive and 3 Gram-negative pathogens, including Lactococcus garvieae, Photobacteria damsella, Vibrio alginolyticus and Vibrio parahemolyticus especially in prawn pathogen of L. garvieae strain, which were carried out by a disk diffusion method. Prawn received BPE via injection administration at 1-6 μg (g prawn)(-1) significantly increased total haemocyte count (THC), hyaline cell (HC), granular cell (GC), phenoloxidase (PO) activity and phagocytic activity against L. garvieae from 3 to 6 days, and significantly increased clearance efficiency against L. garvieae and a significantly decreased coagulation time of prawn from 1 to 6 days. Prawn injected with BPE at 6.0 μg (g prawn)(-1) for 6 days showed significantly increased superoxide dismutase (SOD) activity, but significantly decreased respiratory bursts (RBs) of per haemocyte. Survival rates of M. rosenbergii injected with BPE at concentrations of 1, 3 and 6 μg (g prawn)(-1) were significantly higher than those injected with saline control after challenge with L. garvieae for 4-6 days, and the respective relative survival percentages of prawn were 28.6%, 38.1%, and 47.8%, respectively at 6 days. The sublethal time of prawns that had received saline and BPE at 1, 3 and 6 μg (g prawn)(-1) for 6 days and then were transferred from 28 °C to 14 °C were 69.4, 79.8, 83.6, and 90.2 h, respectively. It was concluded that the BPE can be used as the bacteriostat, and immunostimulant and physiological regulator for prawn through injection administration to enhance immunity, physiological responses, and resistance against L. garvieae

In vitro antibacterial activity of crude extracts of 9 selected medicinal plants against UTI causing MDR bacteria

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Monali P. Mishra

2017-01-01

Full Text Available Urinary tract infection (UTI has become a more grievous problem today, due to multidrug resistance of infecting Gram-positive (GP and Gram-negative (GN bacteria, sometimes even with multiple infections. This study examines effectivity of 9 tropical flowering plants (Anogeissus acuminata, Azadirachta indica, Bauhinia variegata, Boerhaavia diffusa, Punica granatum, Soymida febrifuga, Terminalia chebula, Tinospora cordifolia and Tribulus terrestris for possible use as source of antimicrobials for multidrug resistant (MDR bacteria, along with main-stream antibiotics. Pathogenic bacteria were isolated from urine samples of patients attending and admitted in the hospital. Antibiograms of 11 isolated bacteria (GPs, Enterococcus faecalis and Staphylococcus aureus; and GNs, Acinetobacter baumannii, Citrobacter freundii, Enterobacter aerogenes, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris and Pseudomonas aeruginosa were ascertained by the disc-diffusion method, and antibacterial effectivity of plant extracts was monitored by the agar-well diffusion method. Isolated bacteria were floridly MDR to most antibiotics of the day. Methanol extracts of 9 plants were used, and extracts of 3 plants, A. acuminata, P. granatum and S. febrifuga at least caused 25–29 mm as the maximum size of zone of inhibition on bacterial lawns. Minimum inhibitory concentration (MIC and minimum bactericidal concentration (MBC values of methanol extracts of 9 plants were recorded. The methanol extract of A. acuminata had 0.29 mg/ml as the lowest MIC value and 0.67 mg/ml as the lowest MBC value, against MDR S. aureus, signifying effectivity; but, it had the highest MIC value of 3.41 mg/ml. and the highest MBC value of 4.27 mg/ml for most other MDR bacteria including E. coli. Qualitative phytochemical analysis was done for these 9 plants and information on leading phytochemicals was presented retrieved from PubChem database. Thus

Mitochondrial Insult in a Parkinson's like symptoms model

Science.gov (United States)

Carrizales, Julio; Cantu, Manuel; Plas, Daniel; Daniel Plas Lab Team, Dr.

2014-03-01

Healthy cells require healthy mitochondria. If these organelles are damaged, many health consequences follow. For example, Parkinson's Disease (PD) is a major neurodegenerative disorder of unknown cause, but much evidence points to the mitochondrion as a key player in the onset of this disease. PD has been studied in animal models challenged with toxins that target the mitochondria. In our work, we have used the pesticide, Rotenone, a known inhibitor of protein Complex I in the mitochondrial electron transport chain. When this toxin is applied to the freshwater mollusk, Lymnaea stagnalis, or pond snail, severe motor deficits ensue. In this project, we are studying the direct effects of this toxin on mitochondrial structure and physiology. We expected that the morphology of the organelle may be altered. In addition, it is likely that the mitochondrial membrane potential necessary for normal function may decrease as the electron transport loses the ability to move protons from the matrix to the intermembrane space. we also are going to use Electrophysiology to compare and Identify the difference of the electrical signaling among healthy and unhealthy neurons. HHMI

Modelling spatial distribution of snails transmitting parasitic worms with importance to human and animal health and analysis of distributional changes in relation to climate

DEFF Research Database (Denmark)

Pedersen, Ulrik Bo; Midzi, Nicholas; Mduluza, Takafira

2014-01-01

to naturalists but also of importance to human and animal health. The spatial distribution of freshwater snail intermediate hosts involved in the transmission of schistosomiasis, fascioliasis and paramphistomiasis (i.e. Bulinus globosus, Biomphalaria pfeifferi and Lymnaea natalensis) were modelled by the use...

The fate of received sperm in the reproductive tract of a hermaphroditic snail and its implications for fertilisation.

NARCIS (Netherlands)

Koene, J.M.; Montagne-Wajer, K; Roelofs, D.; ter Maat, A.

2009-01-01

Multiple mating, sperm storage and internal fertilisation enhance sperm competition. The great pond snail can use stored sperm for over three months, and frequently mates with different partners. This hermaphrodite, Lymnaea stagnalis, can also self-fertilise and often produces egg masses containing

Single-cell analysis of peptide expression and electrophysiology of right parietal neurons involved in male copulation behavior of a simultaneous hermaphrodite

NARCIS (Netherlands)

El Filali, Z.; de Boer, P.A.C.M.; Pieneman, A.W.; de Lange, R.P.J.; Jansen, R.F.; Ter Maat, A.; van der Schors, R.C.; Li, K.W.; van Straalen, N.M.; Koene, J.M.

2015-01-01

Male copulation is a complex behavior that requires coordinated communication between the nervous system and the peripheral reproductive organs involved in mating. In hermaphroditic animals, such as the freshwater snail Lymnaea stagnalis, this complexity increases since the animal can behave both as

Interference microscopy under double-wavelet analysis: A new approach to studying cell dynamics

DEFF Research Database (Denmark)

Sosnovtseva, Olga; Pavlov, A.N.; Brazhe, N.A.

2005-01-01

This Letter combines a novel experimental approach to the study of intracellular processes with a newly developed technique for multimode time-series analysis. Experiments are performed on isolated pond snail (Lymnaea stagnalis) neurons. Local variations in the cellular refractive index as detect...

Hormones and growth factors in breast cancer

African Journals Online (AJOL)

Herman-Giddens M. Condylomata acuminata in children and sexual abuse. Genitourin ..... accommodated reasonably easily in the outline of hormone action referred to ... tumours may still respond to hormone manipulation with another type of ...

Morphological Specifications of the Bird Schistosome Cercariae and Surface Carbohydrates as Receptors for Lectins

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I Moebedi

2007-04-01

Full Text Available Background: To determine the morphological specifications of the bird schistosomes cercaria from Lymnaea gedrosiana and to detect the surface carbohydrates as receptors for host lectins in the host-parasite relationship systems such as avian schistosomiasis and human cercarial dermatitis. Methods: One hundred ninety two snails collected from Dezful areas in Khuzestan Province, in the south west of Iran, during 2005-2006 were examined for cercariae using shedding and crushing methods. In addition, surface carbohydrates on the cercariae were detected by lentil (Lens culinaris lectins. Results: From the total number of Lymnaea gedrosiana, which examined for bird schistosomes cercaria, 9(4% snails were found to be infected with furcocercus cercaria of the bird schistosomes (probably Gigantobilharzia sp.. Mannose monosaccharide CH2OH (CHOH4CHO as surface carbohydrate was also detected on the cercariae. Conclusion: Mannose carbohydrate on these cercariae may be used as receptor by lectins.

Ecological modulation of environmental stress: interactions between ultraviolet radiation, epibiotic snail embryos, plants and herbivores.

Science.gov (United States)

Wahl, Martin

2008-05-01

1. The distribution of egg masses of the freshwater snails Lymnaea stagnalis and Planorbarius corneus on the undersides of water lily leaves (e.g. Nuphar lutea) is related to the prevalence of the leaf-mining beetle Galerucella nymphaeae. 2. When given the choice, Planorbarius significantly avoids leaves that were infested by the mining beetle. Conversely, Lymnaea did not discriminate against mined leaves. 3. Intact Nuphar leaves block over 95% of incident ultraviolet radiation. Yet, ultraviolet transmission reaches almost 100% under beetle mining scars. These are several times wider than snail embryos. 4. When exposed to natural sunlight, Lymnaea embryos proved to be resistant to ambient ultraviolet, while Planorbarius embryos were rapidly killed. Thus, one selective advantage of Planorbarius discrimination against mined leaves when depositing its eggs could be the avoidance of ultraviolet radiation passing through mining scars. 5. Other mining-related modifications of the leaves, reduced area, decreased longevity, altered aufwuchs (i.e. biofilm and epibionts) are discussed but seem less relevant for the oviposition preference of Planorbarius. 6. The discriminatory behaviour of this snail species was triggered by water-borne cues emitted by the damaged leaf, not by the eggs or larvae of the beetle. 7. This study illustrates how environmental stress on a given species, ultraviolet radiation in this case, can be ecologically buffered (shading by Nuphar) or enhanced (reduction of Nuphar shading through beetle mining) by associated species. It highlights how the impact of a given stress depends on the identity of the target species as well as on the identity and role of other species in the community.

Effect of benzylaminopurine (BAP) pulsing on in vitro shoot ...

African Journals Online (AJOL)

user

2011-03-28

Mar 28, 2011 ... Research Cluster, Faculty of Science, University Malaya, 50603 Kuala Lumpur, Malaysia. Accepted 12 ... number of bud formation in shoot cultures of Musa acuminata cv. ... In tissue culture, plant growth regulators (PGR) are.

Electron/electron acoustic instability

International Nuclear Information System (INIS)

Gary, S.P.

1987-01-01

The electron acoustic wave becomes a normal mode of an unmagnetized collisionless plasma in the presence of two electron components with similar densities, but strongly disparate temperatures. The characteristic frequency of this mode is the plasma frequency of the cooler electron component. If these two electron components have a relative drift speed several times the thermal speed of the cooler component, the electron/electron acoustic instability may arise. This paper describes the parametric dependences of the threshold drift speed and maximum growth rate of this instability, and compares these with the same properties of the electron/ion acoustic instability. Under the condition of zero current, the electron/ion acoustic instability typically has the lower threshold drift speed, so that observation of the electron/electron acoustic instability is a strong indication of the presence of an electrical current in the plasma

Electronics and electronic systems

CERN Document Server

Olsen, George H

1987-01-01

Electronics and Electronic Systems explores the significant developments in the field of electronics and electronic devices. This book is organized into three parts encompassing 11 chapters that discuss the fundamental circuit theory and the principles of analog and digital electronics. This book deals first with the passive components of electronic systems, such as resistors, capacitors, and inductors. These topics are followed by a discussion on the analysis of electronic circuits, which involves three ways, namely, the actual circuit, graphical techniques, and rule of thumb. The remaining p

Electrons, Electronic Publishing, and Electronic Display.

Science.gov (United States)

Brownrigg, Edwin B.; Lynch, Clifford A.

1985-01-01

Provides a perspective on electronic publishing by distinguishing between "Newtonian" publishing and "quantum-mechanical" publishing. Highlights include media and publishing, works delivered through electronic media, electronic publishing and the printed word, management of intellectual property, and recent copyright-law issues…

Electron-electron Bremsstrahlung for bound target electrons

International Nuclear Information System (INIS)

Haug, E.

2008-01-01

For the process of electron-electron (e-e) Bremsstrahlung the momentum and energy distributions of the recoiling electrons are calculated in the laboratory frame. In order to get the differential cross section and the photon spectrum for target electrons which are bound to an atom, these formulae are multiplied by the incoherent scattering function and numerically integrated over the recoil energy. The effect of atomic binding is most pronounced at low energies of the incident electrons and for target atoms of high atomic numbers. The results are compared to those of previous calculations. (authors)

An assessment of Environmental Conditions and the Benthic Fauna ...

African Journals Online (AJOL)

Sensitive taxa of Dytiscidae, Hydropsychidae and Libellulidae were found only upstream from Obommirem to Buade. The mid portion of the Odaw catchment area were dominated by Oligochaeta, Naedidae and Lymnaea while the lower portion was dominated by the Chironomidae. There was no seasonal variation in the ...

Effect of physiological harvest stages on the composition of bioactive compounds in Cavendish bananas*

Science.gov (United States)

Bruno Bonnet, Christelle; Hubert, Olivier; Mbeguie-A-Mbeguie, Didier; Pallet, Dominique; Hiol, Abel; Reynes, Max; Poucheret, Patrick

2013-01-01

The combined influence of maturation, ripening, and climate on the profile of bioactive compounds was studied in banana (Musa acuminata, AAA, Cavendish, cv. Grande Naine). Their bioactive compounds were determined by the Folin-Ciocalteu assay and high-performance thin layer chromatographic (HPTLC) method. The polyphenol content of bananas harvested after 400 degree days remained unchanged during ripening, while bananas harvested after 600 and 900 degree days exhibited a significant polyphenol increase. Although dopamine was the polyphenol with the highest concentration in banana peels during the green developmental stage and ripening, its kinetics differed from the total polyphenol profile. Our results showed that this matrix of choice (maturation, ripening, and climate) may allow selection of the banana (M. acuminata, AAA, Cavendish, cv. Grande Naine) status that will produce optimal concentrations of identified compounds with human health relevance. PMID:23549844

Alkaloids as taxonomic markers in some species of Magnolia L. and Liriodendron L.

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Mirosław Furmanowa

2014-01-01

Full Text Available Some Magnoliaceae cultivated in Poland were investigated: Liriodendron tulipifera L. and 6 species of magnolia: Magnolia acuminata L., M. denudata Desr., M. kobus DC., M. obovata Thunb., M. salicifolia Maxim. and M. tripetala L. For alkaloid detection in the leaves thin-,layer chromatography was used. In Liriodendron tulipifera L. and in all the Magnolia species liriodenine which exhibits cytostatic activity was detected. The extract of Liriodendron tulipifera L. leaves showed, beside liriodenine other spots on the chromatogram than did the magnolias. Alkaloids can be utilized in the chemotaxonomy of Magnoliaceae as a diagnostic trait. The results of the investigations indicate a certain distinctiveness of M. acuminata L., in agreement with those obtained by way of numerical taxonomy. Most similar as regards alkaloid content in leaves are M. obovata Thunb. and M. tripetala L.

Four new species of the leafhopper genus Kapsa Dworakowska from China (Hemiptera, Cicadellidae, Typhlocybinae, with a key to Chinese species

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Yuehua Song

2012-07-01

Full Text Available In the present paper, four new species, Kapsa acuminata, K. quadrispina, K. puerensis and K. yanheensis spp. n. from southwest China are described and illustrated, and a key to the species recorded from China is provided.

Interplay between electron-phonon and electron-electron interactions

International Nuclear Information System (INIS)

Roesch, O.; Gunnarsson, O.; Han, J.E.; Crespi, V.H.

2005-01-01

We discuss the interplay between electron-electron and electron-phonon interactions for alkali-doped fullerides and high temperature superconductors. Due to the similarity of the electron and phonon energy scales, retardation effects are small for fullerides. This raises questions about the origin of superconductivity, since retardation effects are believed to be crucial for reducing effects of the Coulomb repulsion in conventional superconductors. We demonstrate that by treating the electron-electron and electron-phonon interactions on an equal footing, superconductivity can be understood in terms of a local pairing. The Jahn-Teller character of the important phonons in fullerides plays a crucial role for this result. To describe effects of phonons in cuprates, we derive a t-J model with phonons from the three-band model. Using exact diagonalization for small clusters, we find that the anomalous softening of the half-breathing phonon as well as its doping dependence can be explained. By comparing the solution of the t-J model with the Hartree-Fock approximation for the three-band model, we address results obtained in the local-density approximation for cuprates. We find that genuine many-body results, due to the interplay between the electron-electron and electron-phonon interactions, play an important role for the the results in the t-J model. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Spatio-temporal variability of dinoflagellate assemblages in different salinity regimes in the west coast of India

Digital Repository Service at National Institute of Oceanography (India)

Alkawri, A.A.S.; Ramaiah, N.

2008 at the estuarine sampling location off Siridao. The toxic species, Alexandrium minutum (1171 cells l sup(-1)) followed by Dinophysis acuminata (838 cells l sup(-1)) were found to attain maximum cell numbers among the 10 different toxic species...

Regeneración de palmas en plantaciones y bosques nativos en el santuario de fauna y flora Otún, Quimbaya (Risaralda, Colombia

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Diego Felipe Correa Gómez

2006-01-01

undata, Ch. pinnatifron y P. acuminata. En general, las clases plántulas y juveniles 1 contuvieron la mayor cantidad de individuos, con un máximo del 92% de total de individuos de G. undata encontrados en las urapaneras.

In vitro multiplication of banana (Musa sp.) cv. Grand Naine

African Journals Online (AJOL)

SAM

2014-07-02

Jul 2, 2014 ... with IAA 2.00 mg/l resulted in maximum establishment of cultures in lesser time. MS medium + BAP. 4.00 mg/l + ... is, Musa acuminata (Malaysia) and Musa balbsiana. (India) (Georget et al., 2000). Banana plantlets produced.

Efectos de plantaciones abandonadas de especies exóticas y nativas sobre la regeneración natural de un bosque montano en Colombia

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Jaime Cavelier

1999-12-01

Full Text Available Se realizaron censos de vegetación durante 1994 en una parcela de 0.1 ha. en cada una de las plantaciones abandonadas de Pinus radiata, Cupressus lusitanica, Eucalyptus globulus, Alnus acuminata y en un bosque secundario montano alto en los Andes centrales de Colombia. También fueron recolectados datos de las propiedades físicas y químicas de suelos superficiales. El bosque de regeneración natural tiene el mayor número de especies (33 seguido por las plantaciones de E. globulus (26 y A. acuminata (16. Las plantaciones abandonadas de P. radiata y C. lusitanica, tuvieron sólo tres especies. Entre el bosque de regeneración natural y la plantación de E. globulus hubo solamente once especies en común y solamente siete con la plantación de A. acuminata. Todas estas especies, con excepción de tres, son arbustos del sotobosque dispersados por viento o aves. En el sotobosque de la plantación de P. radiata había una regeneración abundante del árbol nacional de Colombia, Ceroxylum quindiuensis. La altura de los árboles y el área basal fueron significativamente mayores en las plantaciones de P. radiata y C. lusitanica que en el bosque de regeneración natural. De las variables ambientales y biológicas medidas en este estudio, la acumulación de acículas bajo las plantaciones de P. radiata y C. lusitanica y la alta biomasa de raíces finas bajo la plantación de C. lusitanica, podrían ser los principales factores limitantes para el establecimiento de un número mayor de especies del bosque nativo. Las propiedades químicas de los suelos varían ampliamente y no hubo diferencias coherentes entre los suelos bajo especies exóticas y nativas.Vegetation surveys were carried out during 1994 in 0.1. ha plots in abandoned plantations of Pinus radiata, Cupressus lusitanica, Eucalyptus globulus, Alnus acuminata and in a secondary upper montane rain forest in the Central Andes of Colombia. The regeneration forest had the higher number of plant

Cell type-specific sorting of neuropeptides : a mechanism to modulate peptide composition of large dense core vesicles

NARCIS (Netherlands)

Klumperman, J.; Spijker, S.; Minnen, J. van; Sharp-Baker, H.; Smit, A.B.; Geraerts, W.P.M.

1996-01-01

The CNS of Lymnaea stagnalis contains two populations of egg-laying hormone (ELH)-producing neurons that differ in size and topology. In type I neurons, all peptides located C-terminally from the cleavage site Arg-Ser-Arg-Arg180-183 are sorted into secretory large dense-core vesicles (LDCV), whereas

Toxin profiles of five geographical isolates of Dinophysis spp. from North and South America.

Science.gov (United States)

Fux, Elie; Smith, Juliette L; Tong, Mengmeng; Guzmán, Leonardo; Anderson, Donald M

2011-02-01

Marine dinoflagellates of the genus Dinophysis can produce toxins of the okadaic acid (OA) and pectenotoxin (PTX) groups. These lipophilic toxins accumulate in filter-feeding shellfish and cause an illness in consumers called diarrhetic shellfish poisoning (DSP). In 2008, a bloom of Dinophysis led to the closure of shellfish harvesting areas along the Texas coast, one of the first DSP-related closures in the U.S. This event resulted in a broad study of toxin production in isolates of Dinophysis spp. from U.S. waters. In the present study, we compared toxin profiles in geographical isolates of Dinophysis collected in the U.S. (Eel Pond, Woods Hole MA; Martha's Vineyard, MA; and Port Aransas Bay, Texas), and in those from Canada (Blacks Harbour, Bay of Fundy) and Chile (Reloncavi Estuary), when cultured in the laboratory under the same conditions. For each isolate, the mitochondrial cox1 gene was sequenced to assist in species identification. Strains from the northeastern U.S. and Canada were all assigned to Dinophysis acuminata, while those from Chile and Texas were most likely within the D. acuminata complex whereas precise species designation could not be made with this marker. Toxins were detected in all Dinophysis isolates and each isolate had a different profile. Toxin profiles of isolates from Eel Pond, Martha's Vineyard, and Bay of Fundy were most similar, in that they all contained OA, DTX1, and PTX2. The Eel Pond isolate also contained OA-D8 and DTX1-D7, and low levels (unconfirmed structurally) of DTX1-D8 and DTX1-D9. D. acuminata from Martha's Vineyard produced DTX1-D7, along with OA, DTX1, and PTX2, as identified in both the cells and the culture medium. D. acuminata from the Bay of Fundy produced DTX1 and PTX2, as found in both cells and culture medium, while only trace amounts of OA were detected in the medium. The Dinophysis strain from Texas only produced OA, and the one from Chile only PTX2, as confirmed in both cells and culture medium. Published

Electronic emission and electron guns

International Nuclear Information System (INIS)

Roy, Amitava

2010-01-01

This paper reviews the process of electron emission from metal surface. Although electrons move freely in conductors like metals, they normally do not leave the metal without some manipulation. In fact, heating and bombardment are the two primary ways in which electrons are emitted through the use of a heating element behind the cathode (termed thermionic emission) or as a result of bombardment with a beam of electrons, ions, or metastable atoms (termed secondary emission). Another important emission mechanism called Explosive Electron Emission (EEE) is also often used in various High Voltage Pulse Power Systems to generate very high current (few hundreds of kA) pulsed electron beams. The electron gun is the device in that it shoots off a continuous (or pulsed) stream of electrons. A brief idea about the evolution of the electron gun components and their basis of functioning are also discussed. (author)

Irinotecan: from clinical pharmacokinetics to pharmacogenetics

NARCIS (Netherlands)

A.H.J. Mathijssen (Ron)

2002-01-01

textabstractFour decades ago, a plant alkaloid was isolated from the Chinese tree Camptotheca acuminata (Nyssaceae family), which showed promising antitumor activity in vitro (1 ). At that moment, a relatively new class of anticancer agents was born. Unfortunately, during clinical trials, this

Florae Malesianae Precursores II. The Convolvulaceae of Malaysia IX

NARCIS (Netherlands)

Hoogland, R.D.

1953-01-01

Erycibe beccariana Hoogl. sp. nov. — Frutex scandens, ramulis junioribus sparsim stellato-hirsutis, adultioribus glabrescentibus cortice rimis longitudinalibus fisso. Folia elliptica ad elliptico-oblonga, 9—13 X 4— 71/2 cm, apice breviter acuminata, basi rotundata vel minute cordata, supra glabra,

Spaced taste avoidance conditioning in Lymnaea.

Science.gov (United States)

Takigami, Satoshi; Sunada, Hiroshi; Lukowiak, Ken; Sakakibara, Manabu

2014-01-01

We succeeded in taste avoidance conditioning with sucrose as the conditional stimulus (CS) and an electrical stimulus (∼1000V, 80μA) as the unconditional stimulus (US). With 15 paired CS-US presentations on a single day, we were able to elicit both short-term memory (STM) and long-term memory (LTM) persisting for at least one week. However, while STM was elicited with 5, 8, 10, and 20 paired presentations of the CS-US on a single day, LTM was not. We found, however, that if we inserted a 3h interval between a first and a second set of CS-US pairings that both 8 and 20 paired CS-US presentations on a single day was now sufficient to cause LTM formation. Exposing snails to bryostatin before or during training enhanced LTM formation such that 8 paired presentations of the CS-US resulted in LTM. Copyright © 2013 Elsevier Inc. All rights reserved.

Born-Oppenheimer Dynamics, Electronic Friction, and the Inclusion of Electron-Electron Interactions

Science.gov (United States)

Dou, Wenjie; Miao, Gaohan; Subotnik, Joseph E.

2017-07-01

We present a universal expression for the electronic friction as felt by a set of classical nuclear degrees of freedom (DOFs) coupled to a manifold of quantum electronic DOFs; no assumptions are made regarding the nature of the electronic Hamiltonian and electron-electron repulsions are allowed. Our derivation is based on a quantum-classical Liouville equation for the coupled electronic-nuclear motion, followed by an adiabatic approximation whereby electronic transitions are assumed to equilibrate faster than nuclear movement. The resulting form of friction is completely general, but does reduce to previously published expressions for the quadratic Hamiltonian (i.e., Hamiltonians without electronic correlation). At equilibrium, the second fluctuation-dissipation theorem is satisfied and the frictional matrix is symmetric. To demonstrate the importance of electron-electron correlation, we study electronic friction within the Anderson-Holstein model, where a proper treatment of electron-electron interactions shows signatures of a Kondo resonance and a mean-field treatment is completely inadequate.

Banana MaMADS transcription factors are necessary for fruit ripening and molecular tools to promote shelf-life and food security

Science.gov (United States)

Genetic solutions to postharvest crop loss can reduce cost and energy inputs while increasing food security, especially for banana (Musa acuminata), which is a significant component of worldwide food commerce. We have functionally characterized two banana E class (SEPALLATA3 [SEP3]) MADS box genes, ...

Seed oil content and fatty acid composition of annual halophyte ...

African Journals Online (AJOL)

Suaeda acuminata produces two morphologically distinct types of seeds on the same plant. This study was conducted to compare oil content and fatty acid composition of the two seed morphs. Though oil characteristics between dimorphic seeds showed statistically significant difference, these differences were relatively ...

Colchicine and amiprophos-methyl (APM) in polyploidy induction in ...

African Journals Online (AJOL)

Jane

2011-10-12

Oct 12, 2011 ... The objective was to assess the colchicine and amiprophos-methyl (APM) concentration and exposure period in the chromosome duplication of breed banana plants diploids. Banana stem tips were used from the following genotypes: breed diploids (1304-04 [Malaccensis x Madang (Musa acuminata spp.

Senescent spotting of banana peel is inhibited by modified atmosphere packaging

NARCIS (Netherlands)

Choehom, R.; Ketsa, S.; Doorn, van W.G.

2004-01-01

Banana fruit (Musa cavendishii [Musa acuminata] AA Group cv. Sucrier) were placed in trays and held at 29-30 degreesC. Covering the trays with 'Sun wrap' polyvinyl chloride film prevented the early senescent peel spotting, typical for this cultivar. Carbon dioxide and ethylene concentrations within

A Review of the Bio-Activity Relationship of Mistletoes and the ...

African Journals Online (AJOL)

The following six host trees and their mistletoes were investigated: Azadirachta indica (neem), Psidium guajava (guava), Pentaclethra macrophylla (oil-bean), Kola acuminata (cola nut), Persea americana (avocado), and Baphia nitida (cam wood). The work showed that of the six host trees and their mistletoes studied, four ...

21 CFR 182.20 - Essential oils, oleoresins (solvent-free), and natural extractives (including distillates).

Science.gov (United States)

2010-04-01

... (clary sage) Salvia sclarea L. Clover Trifolium spp. Coca (decocainized) Erythroxylum coca Lam. and other spp. of Erythroxylum. Coffee Coffea spp. Cola nut Cola acuminata Schott and Endl., and other spp. of Cola. Coriander Coriandrum sativum L. Cumin (cummin) Cuminum cyminum L. Curacao orange peel (orange...

Colchicine and amiprophos-methyl (APM) in polyploidy induction in ...

African Journals Online (AJOL)

The objective was to assess the colchicine and amiprophos-methyl (APM) concentration and exposure period in the chromosome duplication of breed banana plants diploids. Banana stem tips were used from the following genotypes: breed diploids (1304-04 [Malaccensis x Madang (Musa acuminata spp. banksii)] and ...

Evaluation of genetic diversity between 27 banana cultivars (Musa ...

African Journals Online (AJOL)

Cultivated bananas (Musa spp.) are mostly diploid or triploid cultivars with various combinations of the A and B genomes inherited from their diploid ancestors Musa acuminata Colla. and Musa balbisiana. Colla. respectively. Random amplified polymorphic DNA (RAPD) markers were used to establish the relatedness of 27 ...

Toxin- and cadmium-induced cell death events in tomato suspension cells resemble features of hypersensitive response

NARCIS (Netherlands)

Iakimova, E.T.; Woltering, E.J.; Yordanova, Z.P.

2007-01-01

Elicitors of different origin (fumonisin B1, fungal toxin), camptothecin (alkaloid from Camptotheca acuminata), mastoparan (wasp venom) and the heavy metal (cadmium) were tested for their ability to induce programmed cell death (PCD) in a model system of tomato cell culture, line MsK8. By employing

Recovery of active pathogenesis-related enzymes from the apoplast ...

African Journals Online (AJOL)

Overall protease activity intensity was higher in the symplast. Maximum symplast contamination of the apoplast was 2% as estimated by glucose 6-phosphate dehydrogenase activity, a biochemical marker for symplast. Accumulation of pathogenesis-related enzymatic activities in the apoplast of M. acuminata leaf tissue was ...

PREDICTION DE LA CROISSANCE DU BANANIER PLANTAIN ...

African Journals Online (AJOL)

Hornik K., Stinchcombe M., White H., Auer P. 1994. Degree of approximation results of feedforward networks approximating unknown mapping et their derivatives. Neur. Net. Comp., 6 : 1262 - 1275. Jannoyer M. 1995. Déterminisme du nombre d'or- ganes reproducteurs d'une inflorescence de bananier (Musa acuminata, ...

Wild species of interest for tourism in Manabí and Guayas, Ecuador

Directory of Open Access Journals (Sweden)

Sonia Rosete Blandariz

2018-01-01

Full Text Available Ethnobotany is the discipline that studies the relationships between man and plants. The purpose of the study was to identify the uses of wild species of interest for tourism in Manabí and Guayas. Interviews, walks and field observations were carried out in areas with little disturbed vegetation. Seventeen species were reported with at least one recognized use, some used for the manufacture of artisanal, ornamental objects, and the majority in danger of extinction due to the degradation of their habitat. The species of greatest interest for tourism due to their beauty and degree of scarcity are Attalea colenda (O.F.Cook Balslev & A.J.Hend. (Arecaceae, Brassia jipijapensis Dodson & N.H.Williams (Orchidaceae, Ceiba trischistandra (A. Gray Bakhuisen (Malvaceae, Erythrina megistophylla Diels (Fabaceae, Erythrina smithiana Krukoff Fabaceae, Macroclinium manabinum (Dodson Dodson (Orchidaceae, Passiflora sprucei Mast. (Passifloraceae, Phytelephas aequatorialis Spruce (Arecaceae and Prestoea acuminata (Willd. H.E.Moore var. acuminata (Arecaceae.

Effect of banana pulp and peel flour on physicochemical properties and in vitro starch digestibility of yellow alkaline noodles.

Science.gov (United States)

Ramli, Saifullah; Alkarkhi, Abbas F M; Shin Yong, Yeoh; Min-Tze, Liong; Easa, Azhar Mat

2009-01-01

The present study describes the utilization of banana--Cavendish (Musa acuminata L., cv cavendshii) and Dream (Musa acuminata colla. AAA, cv 'Berangan')--pulp and peel flours as functional ingredients in yellow alkaline noodles. Noodles were prepared by partial substitution of wheat flour with ripe banana pulp or peel flours. In most cases, the starch hydrolysis index, predicted glycaemic index (pGI) and physicochemical properties of cooked noodles were affected by banana flour addition. In general, the pGI values of cooked noodles were in the order; banana peel noodles banana pulp noodles peel flour was higher in total dietary fibre but lower in resistant starch contents than the pulp flour, the low pGI of banana peel noodles was mainly due to its high dietary fibre content. In conclusion, banana pulp and peel flour could be useful for controlling starch hydrolysis of yellow noodles, even though some physicochemical properties of the noodles were altered.

Effective electron-electron and electron-phonon interactions in the Hubbard-Holstein model

International Nuclear Information System (INIS)

Aprea, G.; Di Castro, C.; Grilli, M. . E-mail marco.grilli@roma1.infn.it; Lorenzana, J.

2006-01-01

We investigate the interplay between the electron-electron and the electron-phonon interaction in the Hubbard-Holstein model. We implement the flow-equation method to investigate within this model the effect of correlation on the electron-phonon effective coupling and, conversely, the effect of phonons in the effective electron-electron interaction. Using this technique we obtain analytical momentum-dependent expressions for the effective couplings and we study their behavior for different physical regimes. In agreement with other works on this subject, we find that the electron-electron attraction mediated by phonons in the presence of Hubbard repulsion is peaked at low transferred momenta. The role of the characteristic energies involved is also analyzed

Electron-electron coincidence spectroscopies at surfaces

International Nuclear Information System (INIS)

Stefani, G.; Iacobucci, S.; Ruocco, A.; Gotter, R.

2002-01-01

In the past 20 years, a steadily increasing number of electron-electron coincidence experiments on atoms and molecules have contributed to a deeper understanding of electron-electron correlation effects. In more recent years this technique has been extended to the study of solid surfaces. This class of one photon IN two electrons OUT experiments will be discussed with an emphasis on grazing incidence geometry, that is expected to be particularly suited for studying surfaces. The crucial question of which is the dominant mechanism that leads to ejection of pairs of electron from the surface will be addressed. It will be shown that, depending on the kinematics chosen, the correlated behaviour of the pairs of electrons detected might be singled out from independent particle one

Electron distribution function in electron-beam-excited plasmas

International Nuclear Information System (INIS)

Brau, C.A.

1976-01-01

In monatomic plasmas excited by high-intensity relativistic electron beams, the electron secondary distribution function is dominated by elastic electron-electron collisions at low electron energies and by inelastic electron-atom collisions at high electron energies (above the excitation threshold). Under these conditions, the total rate of excitation by inelastic collisions is limited by the rate at which electron-electron collisions relax the distribution function in the neighborhood of the excitation threshold. To describe this effect quantitatively, an approximate analytic solution of the electron Boltzmann equation is obtained, including both electron-electron and inelastic collisions. The result provides a simple formula for the total rate of excitation

Analysis of genetic variation in different banana ( Musa species ...

African Journals Online (AJOL)

The banana (Musa acuminata Colla) is considered as an important crop plant due to its high economic value as good dietary source. Here, we analyze the genetic relationship of four different banana varieties that are cultivated in south India. Random amplified polymorphic DNAs (RAPDs) fingerprinting of these banana ...

Hard electronics; Hard electronics

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-03-01

Hard material technologies were surveyed to establish the hard electronic technology which offers superior characteristics under hard operational or environmental conditions as compared with conventional Si devices. The following technologies were separately surveyed: (1) The device and integration technologies of wide gap hard semiconductors such as SiC, diamond and nitride, (2) The technology of hard semiconductor devices for vacuum micro- electronics technology, and (3) The technology of hard new material devices for oxides. The formation technology of oxide thin films made remarkable progress after discovery of oxide superconductor materials, resulting in development of an atomic layer growth method and mist deposition method. This leading research is expected to solve such issues difficult to be easily realized by current Si technology as high-power, high-frequency and low-loss devices in power electronics, high temperature-proof and radiation-proof devices in ultimate electronics, and high-speed and dense- integrated devices in information electronics. 432 refs., 136 figs., 15 tabs.

Electron radiography

Science.gov (United States)

Merrill, Frank E.; Morris, Christopher

2005-05-17

A system capable of performing radiography using a beam of electrons. Diffuser means receive a beam of electrons and diffuse the electrons before they enter first matching quadrupoles where the diffused electrons are focused prior to the diffused electrons entering an object. First imaging quadrupoles receive the focused diffused electrons after the focused diffused electrons have been scattered by the object for focusing the scattered electrons. Collimator means receive the scattered electrons and remove scattered electrons that have scattered to large angles. Second imaging quadrupoles receive the collimated scattered electrons and refocus the collimated scattered electrons and map the focused collimated scattered electrons to transverse locations on an image plane representative of the electrons' positions in the object.

Electron transfer from electronic excited states to sub-vacuum electron traps in amorphous ice

International Nuclear Information System (INIS)

Vichnevetski, E.; Bass, A.D.; Sanche, L.

2000-01-01

We investigate the electron stimulated yield of electronically excited argon atoms (Ar * ) from monolayer quantities of Ar deposited onto thin films of amorphous ice. Two peaks of narrow width ( - electron-exciton complex into exciton states, by the transfer of an electron into a sub-vacuum electron state within the ice film. However, the 10.7 eV feature is shifted to lower energy since electron attachment to Ar occurs within small pores of amorphous ice. In this case, the excess electron is transferred into an electron trap below the conduction band of the ice layer

Physiological and biochemical changes during banana ripening and finger drop

NARCIS (Netherlands)

Imsabai, W.; Ketsa, S.; Doorn, van W.G.

2006-01-01

Fruit drop of banana is due to breaking at the junction of the pedicel and pulp, and we found no true abscission zone. The breakage seems therefore due to weakening of the peel. We investigated pectin hydrolysis and some properties at the rupture zone, using `Hom Thong` (Musa acuminata, AAA Group)

Effects of relative humidity on banana fruit drop

NARCIS (Netherlands)

Saengpook, C.; Ketsa, S.; Doorn, van W.G.

2007-01-01

Commercial ripening of banana fruit occurs at high relative humidity (RH), which prevents browning of damaged skin areas. In experiments with ripening at high RH (94 ± 1%) the individual fruit (fingers) of `Sucrier¿ (Musa acuminata, AA Group) banana exhibited a high rate of drop. The falling off of

A new species of Combretum from East Borneo

NARCIS (Netherlands)

Exell, A.W.

1954-01-01

Combretum kostermansii Exell, sp. nov. Frutex scandens, ramulis primo fulvo-pilosis et tomentellis demum sparse pilosis, atro-rubris. Folia opposita breviter petiolata, petiolo 1—3 mm longo, piloso, lamina chartacea, ovata vel oblongo-ovata, basi cordata, apice acuminata, 2—7 X 1.8—3.6 cm, supra

Current status of the banana and plantain collection at the USDA-ARS Tropical Agriculture Research Station, Mayaguez, Puerto Rico

Science.gov (United States)

Banana (Musa acuminata Colla. [AA, AAA]; Musa x paradisiaca Colla [ABB, AAAB, AABB]), are large monocotyledonous plants in the Musaceae family and is one of the world’s furthermost important crops in the world. High genetic variability can be found in centers of origin, but the lack of diversity in...

Lack of Ecotypic Differentiation: Plant Response to Elevation, Population Origin, and Wind in the Luquillo Mountains, Puerto Rico

Science.gov (United States)

Ned Fetcher; Roberto A. Cordero; Janice Voltzow

2000-01-01

How important is ecotypic differentiation along elevational gradients in the tropics? Reciprocal transplants of two shrubs, Clibadium erosum (Asteraceae) and Psychotria berteriana (Rubiaceae), and a palm, Prestoea acuminata var. montana (Palmaceae), were used to test for the effect of environment and population origin on growth and physiology in the Luquillo...

Combination with Tadalafil reduces the aphrodisiac activity of Cola ...

African Journals Online (AJOL)

Sexual behavioural parameters of mount latency, mount frequency, genital grooming, anogenital sniffing, and chasing of female animals were recorded in male rats (one hour after administration of extract) by their interaction with a receptive female (1:1) for an observatory period of 1 hour. Cola acuminata and Garcinia kola ...

EFFECTS OF INSECT PEST INFESTATION ON THE CAFFEINE ...

African Journals Online (AJOL)

The caffeine content of nuts of Cola nitida and C. acuminata infested by insect pests in four major geographical zones of Nigeria have been determined and compared with the uninfested ones using high-performance liquid chromatography (HPLC). The findings showed that the infestation has no significant effect on the ...

Monte Carlo study of electron relaxation in graphene with spin polarized, degenerate electron gas in presence of electron-electron scattering

Science.gov (United States)

Borowik, Piotr; Thobel, Jean-Luc; Adamowicz, Leszek

2017-12-01

The Monte Carlo simulation method is applied to study the relaxation of excited electrons in monolayer graphene. The presence of spin polarized background electrons population, with density corresponding to highly degenerate conditions is assumed. Formulas of electron-electron scattering rates, which properly account for electrons presence in two energetically degenerate, inequivalent valleys in this material are presented. The electron relaxation process can be divided into two phases: thermalization and cooling, which can be clearly distinguished when examining the standard deviation of electron energy distribution. The influence of the exchange effect in interactions between electrons with parallel spins is shown to be important only in transient conditions, especially during the thermalization phase.

Temperature effects on peel spotting in "Sucrier banana" fruit

NARCIS (Netherlands)

Trakulnaleumsai, C.; Ketsa, S.; Doorn, van W.G.

2006-01-01

Banana fruit of the cultivar `Sucrier¿ (Musa acuminata, AA Group) develops peel spotting at a relatively early stage of development (when the peel is about as slightly more yellow than green). Holding ripening bananas at 15 and 18 °C instead of room temperature (26¿27 °C) only temporarily reduced

Seed oil content and fatty acid composition of annual halophyte ...

African Journals Online (AJOL)

ajl yemi

2011-12-19

Dec 19, 2011 ... 1State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of. Sciences, Urumqi 830011, China. 2Graduate University of ... of S. acuminata: brown with soft coarse seed coat and black with rigid smooth seed coat (Ding et al., 2010). Brown and black ...

Browse Title Index

African Journals Online (AJOL)

Items 1 - 50 of 88 ... Vol 6, No 1 (2008), Fournier\\'s Gangrene: Irrua Teaching Hospital, Nigeria, Experience. Abstract. E Irekpita, TAT Salami, AE Dongo, KC Eze, MO Momoh, SA Okogbenin. Vol 3, No 3 (2005), Giant condylomata acuminata of buschke and löwenstein - single case report & review, Abstract. Adil HH Bashir.

Florae Malesianae Precursores III. Dialium L. (Caesalpiniaceae)

NARCIS (Netherlands)

Wit, de H.C.D.

1953-01-01

Dialium hydnocarpoides, sp. nov. — Foliola (15)17—19, elliptice oblonga, 4.5—6.5(8.5) cm longa, 2—2.5(3) cm lata, apice abrupte breviter acuminata. Sepala extus pubescentia, intus puberula. Stamina 2, raro 3. Ovarium in receptaculo plano, lato, strigoso excentrice insertum. Stylus glaber. Legumen

Electron attachment cross sections obtained from electron attachment spectroscopy

International Nuclear Information System (INIS)

Popp, P.; Baumbach, J.I.; Leonhardt, J.W.; Mothes, S.

1988-01-01

Electron capture detectors have a high sensitivity for substances with high thermal electron attachment cross sections. The electron attachment spectroscopy makes it possible to change the mean electron energy in such a way that the maximum for dissociative electron attachment is reached. Thus, best operation modes of the detection system as well as significant dependencies of electron attachment coefficients are available. Cross sections for electron attachment as a function of the electron energy are obtained with the knowledge of electron energy distribution functions from Boltzmann equation analysis by a special computer code. A disadvantage of this electron attachment spectroscopy is the superposition of space charge effects due to the decrease of the electron drift velocity with increasing mean electron energy. These influences are discussed. (author)

Electron beam effects in auger electron spectroscopy and scanning electron microscopy

International Nuclear Information System (INIS)

Fontaine, J.M.; Duraud, J.P.; Le Gressus, C.

1979-01-01

Electron beam effects on Si(100) and 5% Fe/Cr alloy samples have been studied by measurements of the secondary electron yield delta, determination of the surface composition by Auger electron spectroscopy and imaging with scanning electron microscopy. Variations of delta as a function of the accelerating voltage Esub(p) (0.5 -9 Torr has no effect on technological samples covered with their reaction layers; the sensitivities to the beam depend rather on the earlier mechanical, thermal and chemical treatment of the surfaces. (author)

The effect of electron-electron interaction induced dephasing on electronic transport in graphene nanoribbons

Energy Technology Data Exchange (ETDEWEB)

Kahnoj, Sina Soleimani; Touski, Shoeib Babaee [School of Electrical and Computer Engineering, University of Tehran, P.O. Box 14395-515, Tehran (Iran, Islamic Republic of); Pourfath, Mahdi, E-mail: pourfath@ut.ac.ir, E-mail: pourfath@iue.tuwien.ac.at [School of Electrical and Computer Engineering, University of Tehran, P.O. Box 14395-515, Tehran (Iran, Islamic Republic of); Institute for Microelectronics, TU Wien, Gusshausstrasse 27–29/E360, 1040 Vienna (Austria)

2014-09-08

The effect of dephasing induced by electron-electron interaction on electronic transport in graphene nanoribbons is theoretically investigated. In the presence of disorder in graphene nanoribbons, wavefunction of electrons can set up standing waves along the channel and the conductance exponentially decreases with the ribbon's length. Employing the non-equilibrium Green's function formalism along with an accurate model for describing the dephasing induced by electron-electron interaction, we show that this kind of interaction prevents localization and transport of electrons remains in the diffusive regime where the conductance is inversely proportional to the ribbon's length.

Electron Beam Generation in Tevatron Electron Lenses

International Nuclear Information System (INIS)

Kamerdzhiev, V.; Kuznetsov, G.; Shiltsev, V.; Solyak, N.; Tiunov, M.

2006-01-01

New type of high perveance electron guns with convex cathode has been developed. Three guns described in this article are built to provide transverse electron current density distributions needed for Electron Lenses for beam-beam compensation in the Tevatron collider. The current distribution can be controlled either by the gun geometry or by voltage on a special control electrode located near cathode. We present the designs of the guns and report results of beam measurements on the test bench. Because of their high current density and low transverse temperature of electrons, electron guns of this type can be used in electron cooling and beam-beam compensation devices

Electron beam generation in Tevatron electron lenses

International Nuclear Information System (INIS)

Kamerdzhiev, V.; Kuznetsov, G.; Shiltsev, V.; Solyak, N.; Tiunov, M.

2006-01-01

New type of high perveance electron guns with convex cathode has been developed. Three guns described in this article are built to provide transverse electron current density distributions needed for Electron Lenses for beam-beam compensation in the Tevatron collider. The current distribution can be controlled either by the gun geometry or by voltage on a special control electrode located near cathode. We present the designs of the guns and report results of beam measurements on the test bench. Because of their high current density and low transverse temperature of electrons, electron guns of this type can be used in electron cooling and beam-beam compensation devices

Electronic technology

International Nuclear Information System (INIS)

Kim, Jin Su

2010-07-01

This book is composed of five chapters, which introduces electronic technology about understanding of electronic, electronic component, radio, electronic application, communication technology, semiconductor on its basic, free electron and hole, intrinsic semiconductor and semiconductor element, Diode such as PN junction diode, characteristic of junction diode, rectifier circuit and smoothing circuit, transistor on structure of transistor, characteristic of transistor and common emitter circuit, electronic application about electronic equipment, communication technology and education, robot technology and high electronic technology.

The Electron

Energy Technology Data Exchange (ETDEWEB)

Thomson, George

1972-01-01

Electrons are elementary particles of atoms that revolve around and outside the nucleus and have a negative charge. This booklet discusses how electrons relate to electricity, some applications of electrons, electrons as waves, electrons in atoms and solids, the electron microscope, among other things.

Determination of the electron-electron collisional frequency by means of plasma electron spectroscopy

International Nuclear Information System (INIS)

Kolokolov, N.B.; Kudryavtsev, A.A.; Romanenko, V.A.

1989-01-01

Methods of controlling fast part of electron distribution function (DF) in nonlocal regime of current-free plasma are suggested and realized. Artificially created step in DF fast part has a simple link with frequencies of electron-electron and elastic electron-atom collisions that may be defined in the corresponding experiments

Electron beam-plasma interaction and electron-acoustic solitary waves in a plasma with suprathermal electrons

Science.gov (United States)

Danehkar, A.

2018-06-01

Suprathermal electrons and inertial drifting electrons, so called electron beam, are crucial to the nonlinear dynamics of electrostatic solitary waves observed in several astrophysical plasmas. In this paper, the propagation of electron-acoustic solitary waves (EAWs) is investigated in a collisionless, unmagnetized plasma consisting of cool inertial background electrons, hot suprathermal electrons (modeled by a κ-type distribution), and stationary ions. The plasma is penetrated by a cool electron beam component. A linear dispersion relation is derived to describe small-amplitude wave structures that shows a weak dependence of the phase speed on the electron beam velocity and density. A (Sagdeev-type) pseudopotential approach is employed to obtain the existence domain of large-amplitude solitary waves, and investigate how their nonlinear structures depend on the kinematic and physical properties of the electron beam and the suprathermality (described by κ) of the hot electrons. The results indicate that the electron beam can largely alter the EAWs, but can only produce negative polarity solitary waves in this model. While the electron beam co-propagates with the solitary waves, the soliton existence domain (Mach number range) becomes narrower (nearly down to nil) with increasing the beam speed and the beam-to-hot electron temperature ratio, and decreasing the beam-to-cool electron density ratio in high suprathermality (low κ). It is found that the electric potential amplitude largely declines with increasing the beam speed and the beam-to-cool electron density ratio for co-propagating solitary waves, but is slightly decreased by raising the beam-to-hot electron temperature ratio.

Fasciola hepatica in snails collected from water-dropwort fields using PCR.

Science.gov (United States)

Kim, Hwang-Yong; Choi, In-Wook; Kim, Yeon-Rok; Quan, Juan-Hua; Ismail, Hassan Ahmed Hassan Ahmed; Cha, Guang-Ho; Hong, Sung-Jong; Lee, Young-Ha

2014-12-01

Fasciola hepatica is a trematode that causes zoonosis mainly in cattle and sheep and occasionally in humans. Fascioliasis has been reported in Korea; however, determining F. hepatica infection in snails has not been done recently. Thus, using PCR, we evaluated the prevalence of F. hepatica infection in snails at 4 large water-dropwort fields. Among 349 examined snails, F. hepatica-specific internal transcribed space 1 (ITS-1) and/or ITS-2 markers were detected in 12 snails and confirmed using sequence analysis. Morphologically, 213 of 349 collected snails were dextral shelled, which is the same aperture as the lymnaeid snail, the vectorial host for F. hepatica. Among the 12 F. hepatica-infected snails, 6 were known first intermediate hosts in Korea (Lymnaea viridis and L. ollula) and the remaining 6 (Lymnaea sp.) were potentially a new first intermediate host in Korea. It has been shown that the overall prevalence of the snails contaminated with F. hepatica in water-dropwort fields was 3.4%; however, the prevalence varied among the fields. This is the first study to estimate the prevalence of F. hepatica infection using the vectorial capacity of the snails in Korea.

Effects of 5-HT and insulin on learning and memory formation in food-deprived snails.

Science.gov (United States)

Aonuma, Hitoshi; Totani, Yuki; Kaneda, Mugiho; Nakamura, Ryota; Watanabe, Takayuki; Hatakeyama, Dai; Dyakonova, Varvara E; Lukowiak, Ken; Ito, Etsuro

2018-02-01

The pond snail Lymnaea stagnalis learns conditioned taste aversion (CTA) and consolidates it into long-term memory (LTM). How well they learn and form memory depends on the degree of food deprivation. Serotonin (5-HT) plays an important role in mediating feeding, and insulin enhances the memory consolidation process following CTA training. However, the relationship between these two signaling pathways has not been addressed. We measured the 5-HT content in the central nervous system (CNS) of snails subjected to different durations of food deprivation. One-day food-deprived snails, which exhibit the best learning and memory, had the lowest 5-HT content in the CNS, whereas 5-day food-deprived snails, which do not learn, had a high 5-HT content. Immersing 1-day food-deprived snails in 5-HT impaired learning and memory by causing an increase in 5-HT content, and that the injection of insulin into these snails reversed this impairment. We conclude that insulin rescues the CTA deficit and this may be due to a decrease in the 5-HT content in the CNS of Lymnaea. Copyright © 2018 Elsevier Inc. All rights reserved.

Molecular analysis and genomic organization of major DNA satellites in banana (Musa spp.).

Science.gov (United States)

Čížková, Jana; Hřibová, Eva; Humplíková, Lenka; Christelová, Pavla; Suchánková, Pavla; Doležel, Jaroslav

2013-01-01

Satellite DNA sequences consist of tandemly arranged repetitive units up to thousands nucleotides long in head-to-tail orientation. The evolutionary processes by which satellites arise and evolve include unequal crossing over, gene conversion, transposition and extra chromosomal circular DNA formation. Large blocks of satellite DNA are often observed in heterochromatic regions of chromosomes and are a typical component of centromeric and telomeric regions. Satellite-rich loci may show specific banding patterns and facilitate chromosome identification and analysis of structural chromosome changes. Unlike many other genomes, nuclear genomes of banana (Musa spp.) are poor in satellite DNA and the information on this class of DNA remains limited. The banana cultivars are seed sterile clones originating mostly from natural intra-specific crosses within M. acuminata (A genome) and inter-specific crosses between M. acuminata and M. balbisiana (B genome). Previous studies revealed the closely related nature of the A and B genomes, including similarities in repetitive DNA. In this study we focused on two main banana DNA satellites, which were previously identified in silico. Their genomic organization and molecular diversity was analyzed in a set of nineteen Musa accessions, including representatives of A, B and S (M. schizocarpa) genomes and their inter-specific hybrids. The two DNA satellites showed a high level of sequence conservation within, and a high homology between Musa species. FISH with probes for the satellite DNA sequences, rRNA genes and a single-copy BAC clone 2G17 resulted in characteristic chromosome banding patterns in M. acuminata and M. balbisiana which may aid in determining genomic constitution in interspecific hybrids. In addition to improving the knowledge on Musa satellite DNA, our study increases the number of cytogenetic markers and the number of individual chromosomes, which can be identified in Musa.

Effects of insect and decapod exclusion and leaf litter species identity on breakdown rates in a tropical headwater stream

Directory of Open Access Journals (Sweden)

José Rincón

2014-04-01

Full Text Available La gran variedad de especies vegetales junto a los ríos tropicales afecta la diversidad de detritos orgánicos que llegan a los arroyos, creando variaciones temporales en cantidad y calidad de hojarasca. Examinamos la influencia de las especies vegetales y de la exclusión de macroinvertebrados sobre la descomposición de hojarasca en la parte alta de un arroyo en las montañas Luquillo de Puerto Rico. Incubamos hojarasca de Dacryodes excelsa (Burseraceae, Guarea guidonia (Meliaceae, Cecropia scheberiana (Moraceae, Manilkara bidentata (Sapotaceae y Prestoea acuminata (Palmae en bolsas descomposición que colocamos en una poza de Quebrada Prieta. Usamos bolsas de malla fina para excluir los macroinvertebrados y de malla gruesa para permitir la entrada a crustáceos decápodos (camarones y cangrejos jóvenes e insectos acuáticos (principalmente efemerópteros, quironómidos y tricópteros. D. excelsa y G. guidonia (en ambos tipos de malla tuvieron tasas de descomposición más altas que C. scheberiana, M. bidentata y P. acuminata. La descomposición fue más rápida para todas las especies de hoja con la malla gruesa, resaltando el papel de los descomponedores en este hábitat. Tras 42 días de esta incubación, las densidades totales de invertebrados, efemerópteros y tricópteros fueron mayores en las bolsas con hojas de D. excelsa y G. guidonia, e inferiores en P. acuminata, C. scheberiana y M. bidentata. A mayor densidad de insectos hubo mayor tasa de descomposición. Nuestros resultados indican la importancia de la especie de las hojas y de la presencia de macroinvertebrados en el proceso de descomposición de hojarasca en partes altas de arroyos tropicales.

A Study to Determine the Best Method of Caring for Certain Short-Stay Surgical Patients at Reynolds Army Community Hospital

Science.gov (United States)

1988-09-01

herniorrhaphy Umbilical sinus, excision Venectomy Ventral hernia GYNECOLOGIC Adhesions of clitoris, release Cervical polypectomy Condylomata acuminata...window Arch bars, removal and placement Branchial arch appendages, excision Bronchoscopy (Rigid) Caldwell-Luc operation Cervical node biopsy Closed...Breast mass, excision Bronchoscopy with operative procedure Cervical node biopsy Debridement of wound, infection, or burn Debridement of chest wall

Changes in antioxidant and fruit quality in hot water-treated ‘Hom Thong’ banana fruit during storage

Science.gov (United States)

The effects of hot water treatment on antioxidant phytochemicals and fruit quality were investigated in banana fruit of cv. Gros Michel (Musa acuminata, AAA Group, locally called cv. Hom Thong) by immersing fruits in hot water (50 'C) for 10 min, before storage at 25 'C for 10 days or 14 'C for 8 da...

The geographical distribution and habitats of three liver fluke intermediate hosts in South - Africa and the health implications involved

Directory of Open Access Journals (Sweden)

K. N. de Kock

2008-09-01

Full Text Available Account is given of the distribution and habitats of the three Lymnaea species currently on recordin the National Freshwater Snail Collection (NFSC of South Africa. A total number of 616, 353and 202 loci (1/16th square degrees was respectively recorded for Lymnaea natalensis, L. columellaand L. truncatula. The number of loci in which the collection sites of each species was located, wasdistributed in intervals of mean annual air temperature and rainfall, as well as intervals of meanaltitude. A temperature index was calculated for all mollusc species in the database and the resultsused to rank them in order of their association with low to high climatic temperatures. Chi-squareand effect size values were calculated to determine the significance in differences between frequencies of occurrence of each species in, on, or at the different options for each of the variables investigated and also to determine the significance of the differences between the three species. None of the three Lymnaea species were well represented in the arid regions of the Northern ,Western and Eastern Cape Province, and only L. truncatula was reported from Lesotho. Lymnaeanatalensis is the most widespread of the three species, while the distribution of L. truncatula displaysa sporadic and limited pattern. The alien invader species L. columella was first reported from SouthAfrica in the early 1940’s but was so successful in its invasion of water-bodies in South Africa thatit is currently considered the third most widespread freshwater snail in the country. Lymnaea truncatula was the only one of the three species not recovered from all 14 water-body types represented in the database. The largest number of samples of L. truncatula by far, was yielded by marshes while the largest number of samples of the other two species was collected in rivers, streams and dams. The highest percentage occurrence of all three species was in habitats in which the water conditions were

Genome-Wide Analysis of the Musa WRKY Gene Family: Evolution and Differential Expression during Development and Stress.

Science.gov (United States)

Goel, Ridhi; Pandey, Ashutosh; Trivedi, Prabodh K; Asif, Mehar H

2016-01-01

The WRKY gene family plays an important role in the development and stress responses in plants. As information is not available on the WRKY gene family in Musa species, genome-wide analysis has been carried out in this study using available genomic information from two species, Musa acuminata and Musa balbisiana. Analysis identified 147 and 132 members of the WRKY gene family in M. acuminata and M. balbisiana, respectively. Evolutionary analysis suggests that the WRKY gene family expanded much before the speciation in both the species. Most of the orthologs retained in two species were from the γ duplication event which occurred prior to α and β genome-wide duplication (GWD) events. Analysis also suggests that subtle changes in nucleotide sequences during the course of evolution have led to the development of new motifs which might be involved in neo-functionalization of different WRKY members in two species. Expression and cis-regulatory motif analysis suggest possible involvement of Group II and Group III WRKY members during various stresses and growth/development including fruit ripening process respectively.

Genetic resources in Musa bananas and improvement of their disease resistance

International Nuclear Information System (INIS)

Borges Fuentes, O.L.

1977-01-01

The cultivated bananas belong to the genus Musa and it is the wild species Musa acuminata and Musa balbisiana which contributed to the origin of the sorts used as food. Most of these are triploids and possess a high degree of sterility. The sources of variation that are of importance for genetic improvement of the bananas are (1) hereditary differences between the cultivated clones; (2) difference between species and sub-species; (3) differences between the primitive cultivars derived from Musa acuminata, and (4) mutations that can be artiificially induced. The bananas are attacked by many diseases. Their vulnerability to certain diseases is highly significant in view of the extreme genetic uniformity of the commercial crops and the absence of resistant genes. In the past the wild species and the diploids used as food served as sources of resistance. However, efforts to induce resistance in the cultivated triploid bananas have not been successful. The use of mutagenic agents is proposed as a possible way of improving genetic variability in banana cultivation. (author)

Antiviral activity of some South American medicinal plants.

Science.gov (United States)

Abad, M J; Bermejo, P; Sanchez Palomino, S; Chiriboga, X; Carrasco, L

1999-03-01

Folk medicinal plants are potential sources of useful therapeutic compounds including some with antiviral activities. Extracts prepared from 10 South American medicinal plants (Baccharis trinervis, Baccharis teindalensis, Eupatorium articulatum, Eupatorium glutinosum, Tagetes pusilla, Neurolaena lobata, Conyza floribunda, Phytolacca bogotensis, Phytolacca rivinoides and Heisteria acuminata) were screened for in vitro antiviral activity against herpes simplex type I (HSV-1), vesicular stomatitis virus (VSV) and poliovirus type 1. The most potent inhibition was observed with an aqueous extract of B. trinervis, which inhibited HSV-1 replication by 100% at 50-200 micrograms/mL, without showing cytotoxic effects. Good activities were also found with the ethanol extract of H. acuminata and the aqueous extract of E. articulatum, which exhibited antiviral effects against both DNA and RNA viruses (HSV-1 and VSV, respectively) at 125-250 micrograms/mL. The aqueous extracts of T. pusilla (100-250 micrograms/mL), B. teindalensis (50-125 micrograms/mL) and E. glutinosum (50-125 micrograms/mL) also inhibited the replication of VSV, but none of the extracts tested had any effect on poliovirus replication.

Genome-wide analysis of the Musa WRKY gene family: evolution and differential expression during development and stress

Directory of Open Access Journals (Sweden)

Ridhi eGoel

2016-03-01

Full Text Available The WRKY gene family plays an important role in the development and stress responses in plants. As information is not available on the WRKY gene family in Musa species, genome-wide analysis has been carried out in this study using available genomic information from two species, Musa acuminata and Musa balbisiana. Analysis identified 147 and 132 members of the WRKY gene family in M. acuminata and M. balbisiana respectively. Evolutionary analysis suggests that the WRKY gene family expanded much before the speciation in both the species. Most of the orthologs retained in two species were from the γ duplication event which occurred prior to α and β genome-wide duplication (GWD events. Analysis also suggests that subtle changes in nucleotide sequences during the course of evolution have led to the development of new motifs which might be involved in neo-functionalization of different WRKY members in two species. Expression and cis-regulatory motif analysis suggest possible involvement of Group II and Group III WRKY members during various stresses and growth/ development including fruit ripening process respectively.

Potentiation of zinc stress caused by parastic infection of snails

Energy Technology Data Exchange (ETDEWEB)

Guth, D.J. (Univ. of Michigan, Flint); Blankespoor, H.D.; Cairns, J. Jr.

1977-09-08

The purpose of this experiment was to determine the effects of parasitism (Schistosomatium douthitti Price and Trichobilharzia sp.) on the tolerance of snails Lymnaea stagnalis (L.) to acutely lethal concentrations of zinc. Significant reduction in tolerance occurred for snails with patent infections at 24 and 75 ppM of Zn/sup + +/. At two selected prepatent levels of parasite development, significant differences occurred at the higher concentration only.

Habitat stability, predation risk and ‘memory syndromes’

OpenAIRE

S. Dalesman; A. Rendle; S.R.X. Dall

2015-01-01

Habitat stability and predation pressure are thought to be major drivers in the evolutionary maintenance of behavioural syndromes, with trait covariance only occurring within specific habitats. However, animals also exhibit behavioural plasticity, often through memory formation. Memory formation across traits may be linked, with covariance in memory traits (memory syndromes) selected under particular environmental conditions. This study tests whether the pond snail, Lymnaea stagnalis, demonst...

Electronic Government and Electronic Participation

NARCIS (Netherlands)

Tambouris, E; Scholl, H.J.; Janssen, M.F.W.H.A.; Wimmer, M.A.; Tarabanis, K; Gascó, M; Klievink, A.J.; Lindgren, I; Milano, M; Panagiotopoulos, P; Pardo, T.A.; Parycek, P; Sæbø, Ø

2016-01-01

Electronic government and electronic participation continue to transform the public sector and society worldwide and are constantly being transformed themselves by emerging information and communication technologies.This book presents papers from the 14th International Federation for Information

Electronic Government and Electronic Participation

NARCIS (Netherlands)

Tambouris, E.; Scholl, H.J.; Janssen, M.F.W.H.A.; Wimmer, M.A.; Tarabanis, K.; Gascó, M.; Klievink, A.J.; Lindgren, I.; Milano, M.; Panagiotopoulos, P.; Pardo, T.A.; Parycek, P.; Sæbø, O.

2015-01-01

Electronic government and electronic participation continue to transform the public sector and society worldwide and are constantly being transformed themselves by emerging information and communication technologies. This book presents papers from the 14th International Federation for Information

Hot water treatments delay cold-induced banana peel blackening

NARCIS (Netherlands)

Promyou, S.; Ketsa, S.; Doorn, van W.G.

2008-01-01

Banana fruit of cv. Gros Michel (Musa acuminata, AAA Group, locally called cv. Hom Thong) and cv. Namwa (Musa x paradisiaca, ABB Group) were immersed for 5, 10 and 15 min in water at 42 degrees C, or in water at 25 degrees C (control), and were then stored at 4 degrees C. Hot water treatment for 15

2018-02-16T09:03:05Z https://www.ajol.info/index.php/all/oai oai:ojs ...

African Journals Online (AJOL)

Key Words: Banana, interspecific hybridisation, ploidy level, RAPD Résumé Les bananes cultivées obtenues par hybridation interspécifique de deux diploides sauvages (2n=2x=22), Musa acuminata and M. balbisiana étaient les donneurs des génomes A et B, respectivement. La plupart des bananes cultivées sont ...

Electron detector

International Nuclear Information System (INIS)

Hashimoto, H.; Mogami, A.

1975-01-01

A device for measuring electron densities at a given energy level in an electron beam or the like having strong background noise, for example, in the detection of Auger electric energy spectrums is described. An electron analyzer passes electrons at the given energy level and at the same time electrons of at least one adjacent energy level. Detecting means associated therewith produce signals indicative of the densities of the electrons at each energy level and combine these signals to produce a signal indicative of the density of the electrons of the given energy level absent background noise

Electron-electron interactions in artificial graphene

Science.gov (United States)

Rasanen, Esa

2013-03-01

Recent advances in the creation and modulation of graphenelike systems are introducing a science of ``designer Dirac materials.'' In its original definition, artificial graphene is a man-made nanostructure that consists of identical potential wells (quantum dots) arranged in an adjustable honeycomb lattice in the two-dimensional electron gas. As our ability to control the quality of artificial graphene samples improves, so grows the need for an accurate theory of its electronic properties, including the effects of electron-electron interactions. Here we determine those effects on the band structure and on the emergence of Dirac points, and discuss future investigations and challenges in this field.

Decal electronics for printed high performance cmos electronic systems

KAUST Repository

Hussain, Muhammad Mustafa

2017-11-23

High performance complementary metal oxide semiconductor (CMOS) electronics are critical for any full-fledged electronic system. However, state-of-the-art CMOS electronics are rigid and bulky making them unusable for flexible electronic applications. While there exist bulk material reduction methods to flex them, such thinned CMOS electronics are fragile and vulnerable to handling for high throughput manufacturing. Here, we show a fusion of a CMOS technology compatible fabrication process for flexible CMOS electronics, with inkjet and conductive cellulose based interconnects, followed by additive manufacturing (i.e. 3D printing based packaging) and finally roll-to-roll printing of packaged decal electronics (thin film transistors based circuit components and sensors) focusing on printed high performance flexible electronic systems. This work provides the most pragmatic route for packaged flexible electronic systems for wide ranging applications.

Electron-beam-induced-current and active secondary-electron voltage-contrast with aberration-corrected electron probes

Energy Technology Data Exchange (ETDEWEB)

Han, Myung-Geun, E-mail: mghan@bnl.gov [Condensed Matter Physics & Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Garlow, Joseph A. [Condensed Matter Physics & Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Materials Science and Engineering Department, Stony Brook University, Stony Brook, NY 11794 (United States); Marshall, Matthew S.J.; Tiano, Amanda L. [Department of Chemistry, Stony Brook University, Stony Brook, NY 11974 (United States); Wong, Stanislaus S. [Condensed Matter Physics & Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States); Department of Chemistry, Stony Brook University, Stony Brook, NY 11974 (United States); Cheong, Sang-Wook [Department of Physics and Astronomy, Rutgers Center for Emergent Materials, Rutgers University, Piscataway, NJ 08854 (United States); Walker, Frederick J.; Ahn, Charles H. [Department of Applied Physics and Center for Research on Interface Structures and Phenomena, Yale University, New Haven, CT 06520 (United States); Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT 06520 (United States); Zhu, Yimei [Condensed Matter Physics & Materials Science, Brookhaven National Laboratory, Upton, NY 11973 (United States)

2017-05-15

Highlights: • Electron-beam-induced-current (EBIC) and active secondary-electron voltage-contrast (SE-VC) are demonstrated in STEM mode combined with in situ electrical biasing in a TEM. • Electrostatic potential maps in ferroelectric thin films, multiferroic nanowires, and single crystals obtained by off-axis electron holography were compared with EBIC and SE-VC data. • Simultaneous EBIC and active SE-VC performed with atomic resolution STEM are demonstrated. - Abstract: The ability to map out electrostatic potentials in materials is critical for the development and the design of nanoscale electronic and spintronic devices in modern industry. Electron holography has been an important tool for revealing electric and magnetic field distributions in microelectronics and magnetic-based memory devices, however, its utility is hindered by several practical constraints, such as charging artifacts and limitations in sensitivity and in field of view. In this article, we report electron-beam-induced-current (EBIC) and secondary-electron voltage-contrast (SE-VC) with an aberration-corrected electron probe in a transmission electron microscope (TEM), as complementary techniques to electron holography, to measure electric fields and surface potentials, respectively. These two techniques were applied to ferroelectric thin films, multiferroic nanowires, and single crystals. Electrostatic potential maps obtained by off-axis electron holography were compared with EBIC and SE-VC to show that these techniques can be used as a complementary approach to validate quantitative results obtained from electron holography analysis.

Electronic Commerce and Electronic Business

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

This special issue is motivated by the recent upsurge of research activity in the areas of electronic commerce and electronic business both in India and all over the world. The current ... Monte Carlo methods for pricing financial options are then.

Electron optical characteristics of a concave electrostatic electron mirror for a scanning electron microscope

International Nuclear Information System (INIS)

Hamarat, R.T.; Witzani, J.; Hoerl, E.M.

1984-08-01

Numerical computer calculations are used to explore the design characteristics of a concave electrostatic electron mirror for a mirror attachment for a conventional scanning electron microscope or an instrument designed totally as a scanning electron mirror microscope. The electron paths of a number of set-ups are calculated and drawn graphically in order to find the optimum shape and dimensions of the mirror geometry. This optimum configuration turns out to be the transition configuration between two cases of electron path deflection, towards the optical axis of the system and away from it. (Author)

Electronic processes in organic electronics bridging nanostructure, electronic states and device properties

CERN Document Server

Kudo, Kazuhiro; Nakayama, Takashi; Ueno, Nobuo

2015-01-01

The book covers a variety of studies of organic semiconductors, from fundamental electronic states to device applications, including theoretical studies. Furthermore, innovative experimental techniques, e.g., ultrahigh sensitivity photoelectron spectroscopy, photoelectron yield spectroscopy, spin-resolved scanning tunneling microscopy (STM), and a material processing method with optical-vortex and polarization-vortex lasers, are introduced. As this book is intended to serve as a textbook for a graduate level course or as reference material for researchers in organic electronics and nanoscience from electronic states, fundamental science that is necessary to understand the research is described. It does not duplicate the books already written on organic electronics, but focuses mainly on electronic properties that arise from the nature of organic semiconductors (molecular solids). The new experimental methods introduced in this book are applicable to various materials (e.g., metals, inorganic and organic mater...

Decal electronics for printed high performance cmos electronic systems

KAUST Repository

Hussain, Muhammad Mustafa; Sevilla, Galo Torres; Cordero, Marlon Diaz; Kutbee, Arwa T.

2017-01-01

High performance complementary metal oxide semiconductor (CMOS) electronics are critical for any full-fledged electronic system. However, state-of-the-art CMOS electronics are rigid and bulky making them unusable for flexible electronic applications

Plant Guide: Tapertip hawksbeard (Crepis acuminata Nutt.)

Science.gov (United States)

Derek Tilley; Scott Jensen; Loren St. John

2012-01-01

Tapertip hawksbeard leaves are consumed by pre-laying sage grouse hens and make up a large portion of their diet (Barnett and Crawford, 1994). Sage grouse chicks also feed on tapertip hawksbeard leaves in addition to the insects attracted by the flowers (Drut and others, 1994; Klebenow and Gray, 1968).

Precession mechanism of spin relaxation at frequent electron-electron collisions

CERN Document Server

Glazov, M M

2002-01-01

It is shown that the spin relaxation mechanism in the two-dimensional electron gas, is controlled not only through the electron pulse relaxation processes, determining the mobility, but through the electron-electron collisions as well. It is decided to use the kinetic equation, describing the electron spin mixing in the k-space, for determining the spin relaxation time tau sub s at frequent electron-electron collisions. The tau sub s time is calculated for the nondegenerated electron gas both with an account and with no account of the exchange interaction

Practical electronics handbook

CERN Document Server

Sinclair, Ian R

2013-01-01

Practical Electronics Handbook, Third Edition provides the frequently used and highly applicable principles of electronics and electronic circuits.The book contains relevant information in electronics. The topics discussed in the text include passive and active discrete components; linear and digital I.C.s; microprocessors and microprocessor systems; digital-analogue conversions; computer aids in electronics design; and electronic hardware components.Electronic circuit constructors, service engineers, electronic design engineers, and anyone with an interest in electronics will find the book ve

Composition quantification of electron-transparent samples by backscattered electron imaging in scanning electron microscopy

Energy Technology Data Exchange (ETDEWEB)

Müller, E., E-mail: erich.mueller@kit.edu; Gerthsen, D.

2017-02-15

The contrast of backscattered electron (BSE) images in scanning electron microscopy (SEM) depends on material parameters which can be exploited for composition quantification if some information on the material system is available. As an example, the In-concentration in thin In{sub x}Ga{sub 1−x}As layers embedded in a GaAs matrix is analyzed in this work. The spatial resolution of the technique is improved by using thin electron-transparent specimens instead of bulk samples. Although the BSEs are detected in a comparably small angular range by an annular semiconductor detector, the image intensity can be evaluated to determine the composition and local thickness of the specimen. The measured intensities are calibrated within one single image to eliminate the influence of the detection and amplification system. Quantification is performed by comparison of experimental and calculated data. Instead of using time-consuming Monte-Carlo simulations, an analytical model is applied for BSE-intensity calculations which considers single electron scattering and electron diffusion. - Highlights: • Sample thickness and composition are quantified by backscattered electron imaging. • A thin sample is used to achieve spatial resolution of few nanometers. • Calculations are carried out with a time-saving electron diffusion model. • Small differences in atomic number and density detected at low electron energies.

Parasites in a man-made landscape: contrasting patterns of trematode flow in a fishpond area in Central Europe

Czech Academy of Sciences Publication Activity Database

Soldánová, Miroslava; Faltýnková, Anna; Scholz, Tomáš; Kostadinova, Aneta

2011-01-01

Roč. 138, č. 6 (2011), 789-807 ISSN 0031-1820 R&D Projects: GA ČR GAP505/10/1562; GA ČR GD206/09/H026; GA MŠk LC522 Institutional research plan: CEZ:AV0Z60220518 Keywords : Lymnaea stagnalis * trematode community structure * spatial variation * parasite flow * eutrophic fishponds Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 2.961, year: 2011

Nonlinear electron-acoustic rogue waves in electron-beam plasma system with non-thermal hot electrons

Science.gov (United States)

Elwakil, S. A.; El-hanbaly, A. M.; Elgarayh, A.; El-Shewy, E. K.; Kassem, A. I.

2014-11-01

The properties of nonlinear electron-acoustic rogue waves have been investigated in an unmagnetized collisionless four-component plasma system consisting of a cold electron fluid, non-thermal hot electrons obeying a non-thermal distribution, an electron beam and stationary ions. It is found that the basic set of fluid equations is reduced to a nonlinear Schrodinger equation. The dependence of rogue wave profiles on the electron beam and energetic population parameter are discussed. The results of the present investigation may be applicable in auroral zone plasma.

Electron-cyclotron-resonant-heated electron distribution functions

International Nuclear Information System (INIS)

Matsuda, Y.; Nevins, W.M.; Cohen, R.H.

1981-01-01

Recent studies at Lawrence Livermore National Laboratory (LLNL) with a bounce-averaged Fokker-Planck code indicate that the energetic electron tail formed by electron-cyclotron resonant heating (ECRH) at the second harmonic is not Maxwellian. We present the results of our bounce-averaged Fokker-Planck code along with some simple analytic models of hot-electron distribution functions

Attainment of Electron Beam Suitable for Medium Energy Electron Cooling

International Nuclear Information System (INIS)

Seletskiy, Sergey M.; Rochester U.

2005-01-01

Electron cooling of charged particle beams is a well-established technique at electron energies of up to 300 keV. However, up to the present time the advance of electron cooling to the MeV-range energies has remained a purely theoretical possibility. The electron cooling project at Fermilab has recently demonstrated the first cooling of 8.9 GeV/c antiprotons in the Recycler ring, and therefore, has proved the validity of the idea of relativistic electron cooling. The Recycler Electron Cooler (REC) is the key component of the Tevatron Run II luminosity upgrade project. Its performance depends critically on the quality of electron beam. A stable electron beam of 4.3 MeV carrying 0.5 A of DC current is required. The beam suitable for the Recycler Electron Cooler must have an angular spread not exceeding 200 (micro)rad. The full-scale prototype of the REC was designed, built and tested at Fermilab in the Wideband laboratory to study the feasibility of attaining the high-quality electron beam. In this thesis I describe various aspects of development of the Fermilab electron cooling system, and the techniques used to obtain the electron beam suitable for the cooling process. In particular I emphasize those aspects of the work for which I was principally responsible. Chapter 1 is an introduction where I describe briefly the theory and the history of electron cooling, and derive the requirements to the quality of electron beam and requirements to the basic parameters of the Recycler Electron Cooler. Chapter 2 is devoted to the theoretical consideration of the motion of electrons in the cooling section, description of the cooling section and of the measurement of the magnetic fields. In Chapter 3 I consider different factors that increase the effective electron angle in the cooling section and suggest certain algorithms for the suppression of parasitic angles. Chapter 4 is devoted to the measurements of the energy of the electron beam. In the concluding Chapter 5 I review

Double differential distributions of electron emission in ion-atom and electron-atom collisions using an electron spectrometer

International Nuclear Information System (INIS)

Misra, Deepankar; Thulasiram, K.V.; Fernandes, W.; Kelkar, Aditya H.; Kadhane, U.; Kumar, Ajay; Singh, Yeshpal; Gulyas, L.; Tribedi, Lokesh C.

2009-01-01

We study electron emission from atoms and molecules in collisions with fast electrons and heavy ions (C 6+ ). The soft collision electrons (SE), two center electron emission (TCEE), the binary encounter (BE) events and the KLL Auger lines along with the elastically scattered peaks (in electron collisions) are studied using a hemispherical electrostatic electron analyzer. The details of the measurements along with description of the spectrometer and data acquisition system are given. The angular distributions of the low energy (few eV) electrons in soft collisions and the binary encounter electrons at keV energies are compared with quantum mechanical models based on the first Born (B1) and the continuum distorted wave-Eikonal initial state approximation (CDW-EIS).

VIRTUAL ELECTRONIC COMPONENTS OF THE ELECTRONIC EQUIPMENT

Directory of Open Access Journals (Sweden)

E. Lazarevich

2013-01-01

Full Text Available The article is present new idea of the creation, developments and improvements of the electronic equipment of complex systems by means of the virtual electronic components. The idea of the virtual electronic components is a presentation and perception of the creation and developments of the equipment on two forming: real – in the manner of standard marketed block of the intellectual property and image – in the manner of virtual component. The real component in most cases slows the development of the electronic equipment. The imaginary component is the «locomotive» of development of the electronic equipment. The Imaginary component contains the scientific has brushed against developer. The scientific has brushed against developer reveals of itself in the manner of virtual component on the modern level of the design rates of microelectronics.

A new stage of nuclear electronics-particle electronics

International Nuclear Information System (INIS)

Xi Deming

1987-01-01

The rapid development of high energy physics experiments has pushed the nuclear electronics to a new stage, i.e. the particle electronics. In this paper the background, main features and recent trends of the particle electronics are expounded

Electron transport effects in ion induced electron emission

Energy Technology Data Exchange (ETDEWEB)

Dubus, A. [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. FD Roosevelt, B-1050 Brussels (Belgium)]. E-mail: adubus@ulb.ac.be; Pauly, N. [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. FD Roosevelt, B-1050 Brussels (Belgium); Roesler, M. [Karl-Pokern-Str. 12, D-12587 Berlin (Germany)

2007-03-15

Ion induced electron emission (IIEE) is usually described as a three-step process, i.e. electron excitation by the incident projectile, electron transport (and multiplication) and electron escape through the potential barrier at the surface. In many cases, the first step of the process has been carefully described. The second step of the process, i.e. electron transport and multiplication, has often been treated in a very rough way, a simple decreasing exponential law being sometimes used. It is precisely the aim of the present work to show the importance of a correct description of electron transport and multiplication in a theoretical calculation of IIEE. A short overview of the electron transport models developed for IIEE is given in this work. The so-called 'Infinite medium slowing-down model' often used in recent works is evaluated by means of Monte Carlo simulations. In particular, the importance of considering correctly the semi-infinite character of the medium and the boundary condition at the vacuum-medium interface is discussed. Quantities like the electron escape depth are also briefly discussed. This evaluation has been performed in the particular case of protons (25keV

Studying electron-PAG interactions using electron-induced fluorescence

Science.gov (United States)

Narasimhan, Amrit; Grzeskowiak, Steven; Ostrander, Jonathan; Schad, Jonathon; Rebeyev, Eliran; Neisser, Mark; Ocola, Leonidas E.; Denbeaux, Gregory; Brainard, Robert L.

2016-03-01

In extreme ultraviolet (EUV) lithography, 92 eV photons are used to expose photoresists. Typical EUV resists are organic-based and chemically amplified using photoacid generators (PAGs). Upon exposure, PAGs produce acids which catalyze reactions that result in changes in solubility. In EUV lithography, photo- and secondary electrons (energies of 10- 80 eV) play a large role in PAG acid-production. Several mechanisms for electron-PAG interactions (e.g. electron trapping, and hole-initiated chemistry) have been proposed. The aim of this study is to explore another mechanism - internal excitation - in which a bound PAG electron can be excited by receiving energy from another energetic electron, causing a reaction that produces acid. This paper explores the mechanism of internal excitation through the analogous process of electron-induced fluorescence, in which an electron loses energy by transferring that energy to a molecule and that molecule emits a photon rather than decomposing. We will show and quantify electron-induced fluorescence of several fluorophores in polymer films to mimic resist materials, and use this information to refine our proposed mechanism. Relationships between the molecular structure of fluorophores and fluorescent quantum yield may aid in the development of novel PAGs for EUV lithography.

Electron-electron Thomas peak in fast transfer ionization

International Nuclear Information System (INIS)

Tolmanov, S. G.; McGuire, J. H.

2000-01-01

''Thomas process'' is a name used for a family of singular two-step processes that can lead to electron transfer. The Thomas process of the ''second kind,'' occurring in reactions with both transfer and ionization, utilizes the e-e scattering in the second step, so this Thomas process requires the dynamics of the electron-electron interaction. We calculate numerically the second order element of an S matrix and corresponding cross sections for the transfer ionization process. We find that the position and shape of the Thomas peak depend on both electron-electron and the electron-nucleus interaction. Also the direct and exchange amplitudes are equal at the peak position. We test the peaking approximation used for transfer ionization. Our results can be compared to experimental results for p + +He→H+He 2+ +e - . (c) 2000 The American Physical Society

Electron Tree

DEFF Research Database (Denmark)

Appelt, Ane L; Rønde, Heidi S

2013-01-01

The photo shows a close-up of a Lichtenberg figure – popularly called an “electron tree” – produced in a cylinder of polymethyl methacrylate (PMMA). Electron trees are created by irradiating a suitable insulating material, in this case PMMA, with an intense high energy electron beam. Upon discharge......, during dielectric breakdown in the material, the electrons generate branching chains of fractures on leaving the PMMA, producing the tree pattern seen. To be able to create electron trees with a clinical linear accelerator, one needs to access the primary electron beam used for photon treatments. We...... appropriated a linac that was being decommissioned in our department and dismantled the head to circumvent the target and ion chambers. This is one of 24 electron trees produced before we had to stop the fun and allow the rest of the accelerator to be disassembled....

Electronic Raman response in electron-doped cuprate superconductors

International Nuclear Information System (INIS)

Geng Zhihao; Feng Shiping

2012-01-01

The electronic Raman response in the electron-doped cuprate superconductors is studied based on the t-t'-J model. It is shown that although the domelike shape of the doping dependent peak energy in the B 2g symmetry is a common feature for both electron-doped and hole-doped cuprate superconductors, there are pronounced deviations from a cubic response in the B 2g channel and a linear response in the B 2g channel for the electron-doped case in the low energy limit. It is also shown that these pronounced deviations are mainly caused by a nonmonotonic d-wave gap in the electron-doped cuprate superconductors.

Spectroscopy of electron irradiated polymers in electron microscope

International Nuclear Information System (INIS)

Faraj, S.H.; Salih, S.M.

1981-01-01

The damage induced by energetic electrons in the course of irradiation of polymers in a transmission electron microscope was investigated spectroscopically. Damage on the molecular level has been detected at very low exposure doses. These effects have been induced by electron doses less than that received by the specimen when it is situated at its usual place of the specimen stage in the electron microscope by a factor of 1,000. (author)

Electron spectroscopy in the fundamental process of electron-nucleus bremsstrahlung

International Nuclear Information System (INIS)

Hillenbrand, Pierre-Michel

2013-07-01

Within the scope of this thesis the fundamental process of electron-nucleus bremsstrahlung was studied in inverse kinematics at the Experimental Storage Ring ESR at GSI. For the system U 88+ + N 2 at 90 MeV/u it was shown, that by using inverse kinematics coincidence measurements between the scattered electron and the emitted photon can be performed for the case, in which the incoming electron transfers almost all of its kinetic energy onto the emitted photon. The sensitivity to the fundamental process could be achieved by measuring triple differential cross sections as a function of the emission angle of the photon and the scattered electron as well as the energy of the scattered electron. The optics of the magnetic electron spectrometer used were thoroughly revised and optimized to the experimental requirements. Analyzing different coincidences in this collision system, it was possible to determine the contributions to the electron distribution arising from radiative electron capture to the projectile continuum, nonradiative electron capture to the projectile continuum, and electron loss to the projectile continuum. The experimental results of each of these processes were compared to theoretical calculations. The electron spectra for the radiative and the nonradiative electron capture to continuum clearly reproduce the opposite asymmetry predicted by theory. Furthermore electron spectra for collisions of U 28+ with different gases were measured.

`Twisted' electrons

Science.gov (United States)

Larocque, Hugo; Kaminer, Ido; Grillo, Vincenzo; Leuchs, Gerd; Padgett, Miles J.; Boyd, Robert W.; Segev, Mordechai; Karimi, Ebrahim

2018-04-01

Electrons have played a significant role in the development of many fields of physics during the last century. The interest surrounding them mostly involved their wave-like features prescribed by the quantum theory. In particular, these features correctly predict the behaviour of electrons in various physical systems including atoms, molecules, solid-state materials, and even in free space. Ten years ago, new breakthroughs were made, arising from the new ability to bestow orbital angular momentum (OAM) to the wave function of electrons. This quantity, in conjunction with the electron's charge, results in an additional magnetic property. Owing to these features, OAM-carrying, or twisted, electrons can effectively interact with magnetic fields in unprecedented ways and have motivated materials scientists to find new methods for generating twisted electrons and measuring their OAM content. Here, we provide an overview of such techniques along with an introduction to the exciting dynamics of twisted electrons.

The electron

International Nuclear Information System (INIS)

Hestenes, David; Weingartshofer, Antonio

1991-01-01

The stupendous successes of the Dirac equation and quantum electro-dynamics have established the electron as the best understood of the fundamental constituents of matter. Nevertheless, physicists agree that the electron still has secrets to reveal. Moreover, powerful new theoretical and experimental tools for probing those secrets have been sharpened during the last decade. This workshop was organized to bring theorists and experimentalists together to discuss their common goal of knowing the electron. Present state and future prospects for progress toward that goal are here described. The theoretical papers encompass a wide range of views on the electron. Several argue that the 'Zitter-bewegung' is more than a mathematical peculiarity of the Dirac equation, that it may well be a real physical phenomenon and worthy of serious study, theoretically and experimentally. Besides generating the electron spin and magnetic moment, the 'Zitterbewegung' may be a vital clue to electron structure and self-interaction. Some of the papers employ a radical new formulation of the Dirac theory which reveals a hidden geo-metric structure in the theory that supports a 'Zitterbewegung' inter-pretation. For the last half century the properties of electrons have been probed primarily by scattering experiments at ever higher energies. Recently, however, two powerful new experimental techniques have emerged capable of giving alternative experimental views of the electron. First, techniques for confining single electrons for long term study have led to the most accurate measurements of the electron magnetic moment. Second, the interaction of high intensity laser fields with atoms and electrons have revealed striking new phenomena such as multiphoton ionization. refs.; figs.; tabs

Basic electronics

CERN Document Server

Holbrook, Harold D

1971-01-01

Basic Electronics is an elementary text designed for basic instruction in electricity and electronics. It gives emphasis on electronic emission and the vacuum tube and shows transistor circuits in parallel with electron tube circuits. This book also demonstrates how the transistor merely replaces the tube, with proper change of circuit constants as required. Many problems are presented at the end of each chapter. This book is comprised of 17 chapters and opens with an overview of electron theory, followed by a discussion on resistance, inductance, and capacitance, along with their effects on t

Electron-electron scattering and mobilities in semiconductors and quantum wells

International Nuclear Information System (INIS)

Lyo, S.K.

1986-01-01

The effect of electron-electron scattering on the mobility in semiconductors and semiconductor quantum wells is examined. A general exact formula is derived for the mobility, when the electron-electron collision rate is much faster than other scattering rates such as those by ionized impurities and phonons. In this limit, the transport relaxation rate is independent of the carrier's energy and contributions to the inverse mobility from individual scattering mechanism add up. The mobility becomes significantly reduced from its value in the absence of electron-electron scattering. When the collision rates are not necessarily dominated by electron-electron scattering, the mobility is calculated by the Kohler-Sondheimer variational method in the presence of ionized-impurity scattering and acoustic-phonon scattering in a nondegenerate two-dimensional quantum well

Modified Monte Carlo method for study of electron transport in degenerate electron gas in the presence of electron-electron interactions, application to graphene

Science.gov (United States)

Borowik, Piotr; Thobel, Jean-Luc; Adamowicz, Leszek

2017-07-01

Standard computational methods used to take account of the Pauli Exclusion Principle into Monte Carlo (MC) simulations of electron transport in semiconductors may give unphysical results in low field regime, where obtained electron distribution function takes values exceeding unity. Modified algorithms were already proposed and allow to correctly account for electron scattering on phonons or impurities. Present paper extends this approach and proposes improved simulation scheme allowing including Pauli exclusion principle for electron-electron (e-e) scattering into MC simulations. Simulations with significantly reduced computational cost recreate correct values of the electron distribution function. Proposed algorithm is applied to study transport properties of degenerate electrons in graphene with e-e interactions. This required adapting the treatment of e-e scattering in the case of linear band dispersion relation. Hence, this part of the simulation algorithm is described in details.

Field application of a set of cellular biomarkers in the digestive gland of the freshwater snail Radix peregra (Gastropoda, Pulmonata)

International Nuclear Information System (INIS)

Guerlet, Edwige; Ledy, Karine; Giamberini, Laure

2006-01-01

An active biomonitoring study was performed in the vicinity of two pulp and paper mill effluents (PPMEs) released in two different streams in northeastern France. Freshwater gastropods, Radix peregra (=Lymnaea peregra or Lymnaea pereger), were transplanted for 0, 3, 14 and 21 days at two to three sites located upstream and downstream from the mill discharge points in both rivers. Lysosomal and peroxisomal systems, as well as lipofuscin and neutral lipids, were tested using histochemical methods on cryostat sections of digestive gland tissues, and stereological data were obtained by image analysis. Evidence of structural changes in the lysosomal system was found in animals exposed to both effluents, comprising general stress responses such as enlarged and more numerous lysosomes; and also possible specific pluri-phasic effects. Modifications of the lysosomal and cytoplasmic contents of lipid-related materials were also described, namely enhanced lipofuscin deposit and neutral lipid depletion. The peroxisomal proliferation in exposed snails seems to show its implication in oxidative stress detoxication, without preventing higher lipoperoxidation, as indicated by the increased amounts of digestive lipofuscin. Structural changes of the lysosomal and peroxisomal systems, digestive lipofuscin and neutral lipid contents have potential for use as early cellular biomarkers in Radix peregra exposed to environmental stressors, which deserve further investigations

Attainment of Electron Beam Suitable for Medium Energy Electron Cooling

Energy Technology Data Exchange (ETDEWEB)

Seletskiy, Sergei M. [Univ. of Rochester, NY (United States)

2005-01-01

Electron cooling of charged particle beams is a well-established technique at electron energies of up to 300 keV. However, up to the present time the advance of electron cooling to the MeV-range energies has remained a purely theoretical possibility. The electron cooling project at Fermilab has recently demonstrated the ¯rst cooling of 8.9 GeV/c antiprotons in the Recycler ring, and therefore, has proved the validity of the idea of relativistic electron cool- ing. The Recycler Electron Cooler (REC) is the key component of the Teva- tron Run II luminosity upgrade project. Its performance depends critically on the quality of electron beam. A stable electron beam of 4.3 MeV car- rying 0.5 A of DC current is required. The beam suitable for the Recycler Electron Cooler must have an angular spread not exceeding 200 ¹rad. The full-scale prototype of the REC was designed, built and tested at Fermilab in the Wideband laboratory to study the feasibility of attaining the high-quality electron beam. In this thesis I describe various aspects of development of the Fermilab electron cooling system, and the techniques used to obtain the electron beam suitable for the cooling process. In particular I emphasize those aspects of the work for which I was principally responsible.

Microfluidic electronics.

Science.gov (United States)

Cheng, Shi; Wu, Zhigang

2012-08-21

Microfluidics, a field that has been well-established for several decades, has seen extensive applications in the areas of biology, chemistry, and medicine. However, it might be very hard to imagine how such soft microfluidic devices would be used in other areas, such as electronics, in which stiff, solid metals, insulators, and semiconductors have previously dominated. Very recently, things have radically changed. Taking advantage of native properties of microfluidics, advances in microfluidics-based electronics have shown great potential in numerous new appealing applications, e.g. bio-inspired devices, body-worn healthcare and medical sensing systems, and ergonomic units, in which conventional rigid, bulky electronics are facing insurmountable obstacles to fulfil the demand on comfortable user experience. Not only would the birth of microfluidic electronics contribute to both the microfluidics and electronics fields, but it may also shape the future of our daily life. Nevertheless, microfluidic electronics are still at a very early stage, and significant efforts in research and development are needed to advance this emerging field. The intention of this article is to review recent research outcomes in the field of microfluidic electronics, and address current technical challenges and issues. The outlook of future development in microfluidic electronic devices and systems, as well as new fabrication techniques, is also discussed. Moreover, the authors would like to inspire both the microfluidics and electronics communities to further exploit this newly-established field.

Electron-electron collision effects on the bremsstrahlung emission in Lorentzian plasmas

International Nuclear Information System (INIS)

Jung, Young-Dae; Kato, Daiji

2009-01-01

Electron-electron collision effects on the electron-ion bremsstrahlung process are investigated in Lorentzian plasmas. The effective electron-ion interaction potential is obtained by including the far-field terms caused by electron-electron collisions with an effective Debye length in Lorentzian plasmas. The bremsstrahlung radiation cross section is obtained as a function of the electron energy, photon energy, collision frequency, spectral index and Debye length using the Born approximation for the initial and final states of the projectile electron. It is shown that the non-Maxwellian character suppresses the bremsstrahlung radiation cross section. It is also shown that the electron-electron collision effect enhances the bremsstrahlung emission spectrum. In addition, the bremsstrahlung radiation cross section decreases with an increase in the plasma temperature.

Electron-photon and electron-electron interactions in the presence of strong electromagnetic fields

International Nuclear Information System (INIS)

Surzhykov, A.; Fritzsche, S.; Stoehlker, Th.

2010-01-01

During the last decade, photon emission from highly-charged, heavy ions has been in the focus of intense studies at the GSI accelerator and storage ring facility in Darmstadt. These studies have revealed unique information about the electron-electron and electron-photon interactions in the presence of extremely strong nuclear fields. Apart from the radiative electron capture processes, characteristic photon emission following collisional excitation of projectile ions has also attracted much interest. In this contribution, we summarize the recent theoretical studies on the production of excited ionic states and their subsequent radiative decay. We will pay special attention to the angular and polarization properties of Kα emission from helium-like ions produced by means of dielectronic recombination. The results obtained for this (resonant) capture process will be compared with the theoretical predictions for the characteristic X-rays following Coulomb excitation and radiative recombination of few-electron, heavy ions. Work is supported by Helmholtz Association and GSl under the project VH-NG--421. (author)

Sticker electronics

KAUST Repository

Hussain, Muhammad Mustafa

2017-09-08

Electronic stickers may be manufactured on flexible substrates (110, 120, 130) as layers and packaged together. The package may then have an adhesive applied to one side to provide capability for sticking the electronic devices to surfaces. The stickers can be wrappable, placed on surfaces, glued on walls or mirrors or wood or stone, and have electronics (112, 122, 132) which may or may not be ultrathin. Packaging for the electronic sticker can use polymer on cellulose manufacturing and/or three dimensional (3-D) printing. The electronic stickers may provide lighting capability, sensing capability, and/or recharging capabilities.

Electronic Commerce

Directory of Open Access Journals (Sweden)

Slavko Đerić

2016-12-01

Full Text Available Electronic commerce can be defined in different ways. Any definition helps to understand and explain that concept as better as possible.. Electronic commerce is a set of procedures and technologies that automate the tasks of financial transactions using electronic means. Also, according to some authors, electronic commerce is defined as a new concept, which is being developed and which includes process of buying and selling or exchanging products, services or information via computer networks, including the Internet. Electronic commerce is not limited just to buying and selling, but it also includes all pre-sales and after-sales ongoing activities along the supply chain. Introducing electronic commerce, using the Internet and Web services in business, realizes the way to a completely new type of economy - internet economy.

Observation of the two-electron cusp in atomic collisions. Evidence for strong electron-electron correlation

International Nuclear Information System (INIS)

Sarkadi, L.; Orban, A.

2007-01-01

Complete text of publication follows. In this report we present experimental data for a process when two electrons with velocity vectors equal to that of the projectile are emitted from collisions. By observing the two electron cusp the study of the threshold phenomenon for two-electron break-up is possible. It is a particularly interesting question whether the outgoing charged projectile can attract the two repulsing electrons so strongly that the two-electron cusp is formed. If it is so, a further question arises: Are the two electrons correlated in the final state as it is predicted by the Wannier theory? The experiments have been done at the 1 MeV VdG accelerator of ATOMKI using our TOF spectrometer. The first measurements clearly showed the formation of the two-electron cusp and signature of the electron correlation in 200 keV He 0 +He collisions. These promising results motivated us to carry out the experiment at 100 keV beam energy where the coincidence count rate is still reasonable but the energy resolution is better. For an acceptable data acquisition time we improved our data acquisition and data processing system for triple coincidence measurements. In Fig. 1a we present our measured relative fourfold differential cross section (FDCS) that shows strong electron correlation. For a comparison, in Fig. 1b we displayed the contour plot for uncorrelated electron pair emission. These latter data were synthesized artificially, generating the energies of the electron pairs from two independent double coincidence experiments. In both figures the distributions are characterized by two ridges. In Fig. 1b the ridges are perpendicular straight lines (E 1 = E 2 .13.6 eV). As a result of the correlation, the ridges in Fig. 1a are distorted in such a way that they have a joint straight-line section following the line E 1 + E 2 = 27.2 eV. This means that the electron pairs in the vicinity of the cusp maximum are emitted with a center of- mass velocity equal to that of

Electronics and Information

Institute of Scientific and Technical Information of China (English)

无

2008-01-01

@@ Previously founded as CCPITMachinery and Electronics Sub-council and CCOIC Machinery and Electronics Chamber of Corn-merce in June, 1988, CCPIT Electronics Sub-Council and CCOIC Electronics Chamber of Commerce were established in May, 1993, and then renamed as CCPIT Electronics and Information Industry Sub-council and CCOIC Electronics and Infor-mation Industry Chamber of Commerce (CCPITECC) in September 1999.

Spontaneous and stimulated emission induced by an electron, electron bunch, and electron beam in a plasma

International Nuclear Information System (INIS)

Kuzelev, M V; Rukhadze, A A

2008-01-01

Two fundamental mechanisms - the Cherenkov effect and anomalous Doppler effect - underlying the emission by an electron during its superluminal motion in medium are considered. Cherenkov emission induced by a single electron and a small electron bunch is spontaneous. In the course of spontaneous Cherenkov emission, the translational motion of an electron is slowed down and the radiation energy grows linearly with time. As the number of radiating electrons increases, Cherenkov emission becomes stimulated. Stimulated Cherenkov emission represents a resonance beam instability. This emission process is accompanied by longitudinal electron bunching in the beam or by the breaking of an electron bunch into smaller bunches, in which case the radiation energy grows exponentially with time. In terms of the longitudinal size L e of the electron bunch there is a transition region λ e 0 -1 between the spontaneous and stimulated Cherenkov effects, where λ is the average radiation wavelength, and δ 0 is the dimensionless (in units of the radiation frequency) growth rate of the Cherenkov beam instability. The range to the left of this region is dominated by spontaneous emission, whereas the range to the right of this region is dominated by stimulated emission. In contrast to the Vavilov-Cherenkov effect, the anomalous Doppler effect should always (even for a single electron) be considered as stimulated, because it can only be explained by accounting for the reverse action of the radiation field on the moving electron. During stimulated emission in conditions where anomalous Doppler effect shows itself, an electron is slowed down and spins up; in this case, the radiation energy grows exponentially with time. (reviews of topical problems)

High perveance electron gun for the electron cooling system

International Nuclear Information System (INIS)

Korotaev, Yu.; Meshkov, I.; Petrov, A.; Sidorin, A.; Smirnov, A.; Syresin, E.; Titkova, I.

2000-01-01

The cooling time in the electron cooling system is inversely proportional to the beam current. To obtain high current of the electron beam the control electrode of the gun is provided with a positive potential and an electrostatic trap for secondary electrons appears inside the electron gun. This leads to a decrease in the gun perveance. To avoid this problem, the adiabatic high perveance electron gun with the clearing control electrode is designed in JINR (J. Bosser, Y. Korotaev, I. Meshkov, E. Syresin et al., Nucl. Instr. and Meth. A 391 (1996) 103. Yu. Korotaev, I. Meshkov, A. Sidorin, A. Smirnov, E. Syresin, The generation of electron beams with perveance of 3-6 μA/V 3/2 , Proceedings of SCHEF'99). The clearing control electrode has a transverse electric field, which clears secondary electrons. Computer simulations of the potential map were made with RELAX3D computer code (C.J. Kost, F.W. Jones, RELAX3D User's Guide and References Manual)

High perveance electron gun for the electron cooling system

CERN Document Server

Korotaev, Yu V; Petrov, A; Sidorin, A; Smirnov, A; Syresin, E M; Titkova, I

2000-01-01

The cooling time in the electron cooling system is inversely proportional to the beam current. To obtain high current of the electron beam the control electrode of the gun is provided with a positive potential and an electrostatic trap for secondary electrons appears inside the electron gun. This leads to a decrease in the gun perveance. To avoid this problem, the adiabatic high perveance electron gun with the clearing control electrode is designed in JINR (J. Bosser, Y. Korotaev, I. Meshkov, E. Syresin et al., Nucl. Instr. and Meth. A 391 (1996) 103. Yu. Korotaev, I. Meshkov, A. Sidorin, A. Smirnov, E. Syresin, The generation of electron beams with perveance of 3-6 mu A/V sup 3 sup / sup 2 , Proceedings of SCHEF'99). The clearing control electrode has a transverse electric field, which clears secondary electrons. Computer simulations of the potential map were made with RELAX3D computer code (C.J. Kost, F.W. Jones, RELAX3D User's Guide and References Manual).

Study of single-electron excitations by electron microscopy

International Nuclear Information System (INIS)

Craven, A.J.; Gibson, J.M.; Howie, A.; Spalding, D.R.

1978-01-01

The inelastic scattering of fast electrons by the excitation of L-shell electrons at a stacking fault in silicon has been studied with a scanning transmission electron microscope. It was found that the bright-field stacking fault contrast is preserved in the filtered L-shell-loss signal at 100 eV. This result is discussed in terms of the delocalization of the excitation mechanism. It is concluded that localization effects will typically become significant only for energy transfers greater than 1 keV from a fast electron of energy 80 keV. (author)

Syringe injectable electronics

Science.gov (United States)

Hong, Guosong; Zhou, Tao; Jin, Lihua; Duvvuri, Madhavi; Jiang, Zhe; Kruskal, Peter; Xie, Chong; Suo, Zhigang; Fang, Ying; Lieber, Charles M.

2015-01-01

Seamless and minimally-invasive three-dimensional (3D) interpenetration of electronics within artificial or natural structures could allow for continuous monitoring and manipulation of their properties. Flexible electronics provide a means for conforming electronics to non-planar surfaces, yet targeted delivery of flexible electronics to internal regions remains difficult. Here, we overcome this challenge by demonstrating syringe injection and subsequent unfolding of submicrometer-thick, centimeter-scale macroporous mesh electronics through needles with a diameter as small as 100 micrometers. Our results show that electronic components can be injected into man-made and biological cavities, as well as dense gels and tissue, with > 90% device yield. We demonstrate several applications of syringe injectable electronics as a general approach for interpenetrating flexible electronics with 3D structures, including (i) monitoring of internal mechanical strains in polymer cavities, (ii) tight integration and low chronic immunoreactivity with several distinct regions of the brain, and (iii) in vivo multiplexed neural recording. Moreover, syringe injection enables delivery of flexible electronics through a rigid shell, delivery of large volume flexible electronics that can fill internal cavities and co-injection of electronics with other materials into host structures, opening up unique applications for flexible electronics. PMID:26053995

Electronic Nose and Electronic Tongue

Science.gov (United States)

Bhattacharyya, Nabarun; Bandhopadhyay, Rajib

Human beings have five senses, namely, vision, hearing, touch, smell and taste. The sensors for vision, hearing and touch have been developed for several years. The need for sensors capable of mimicking the senses of smell and taste have been felt only recently in food industry, environmental monitoring and several industrial applications. In the ever-widening horizon of frontier research in the field of electronics and advanced computing, emergence of electronic nose (E-Nose) and electronic tongue (E-Tongue) have been drawing attention of scientists and technologists for more than a decade. By intelligent integration of multitudes of technologies like chemometrics, microelectronics and advanced soft computing, human olfaction has been successfully mimicked by such new techniques called machine olfaction (Pearce et al. 2002). But the very essence of such research and development efforts has centered on development of customized electronic nose and electronic tongue solutions specific to individual applications. In fact, research trends as of date clearly points to the fact that a machine olfaction system as versatile, universal and broadband as human nose and human tongue may not be feasible in the decades to come. But application specific solutions may definitely be demonstrated and commercialized by modulation in sensor design and fine-tuning the soft computing solutions. This chapter deals with theory, developments of E-Nose and E-Tongue technology and their applications. Also a succinct account of future trends of R&D efforts in this field with an objective of establishing co-relation between machine olfaction and human perception has been included.

A theory of electron baths: One-electron system dynamics

International Nuclear Information System (INIS)

McDowell, H.K.

1992-01-01

The second-quantized, many-electron, atomic, and molecular Hamiltonian is partitioned both by the identity or labeling of the spin orbitals and by the dynamics of the spin orbitals into a system coupled to a bath. The electron bath is treated by a molecular time scale generalized Langevin equation approach designed to include one-electron dynamics in the system dynamics. The bath is formulated as an equivalent chain of spin orbitals through the introduction of equivalent-chain annihilation and creation operators. Both the dynamics and the quantum grand canonical statistical properties of the electron bath are examined. Two versions for the statistical properties of the bath are pursued. Using a weak bath assumption, a bath statistical average is defined which allows one to achieve a reduced dynamics description of the electron system which is coupled to the electron bath. In a strong bath assumption effective Hamiltonians are obtained which reproduce the dynamics of the bath and which lead to the same results as found in the weak bath assumption. The effective (but exact) Hamiltonian is found to be a one-electron Hamiltonian. A reduced dynamics equation of motion for the system population matrix is derived and found to agree with a previous version. This equation of motion is useful for studying electron transfer in the system when coupled to an electron bath

Treatment of foods with 'soft-electrons' (low-energy electrons)

International Nuclear Information System (INIS)

Hayashi, Toru; Todoriki, Setsuko

2003-01-01

Electrons with energies of 300 keV or lower were defined as soft-electrons'. Soft-electrons can eradicate microorganisms residing on the surface of grains, pulses, spices, dehydrated vegetables, tea leaves and seeds, and reduce their microbial loads to levels lower than 10 CFU/g with little quality deterioration. Soft-electrons can inactivate insect pests infesting grains and pulses and inhibit sprouting of potatoes. (author)

Compact femtosecond electron diffractometer with 100 keV electron bunches approaching the single-electron pulse duration limit

International Nuclear Information System (INIS)

Waldecker, Lutz; Bertoni, Roman; Ernstorfer, Ralph

2015-01-01

We present the design and implementation of a highly compact femtosecond electron diffractometer working at electron energies up to 100 keV. We use a multi-body particle tracing code to simulate electron bunch propagation through the setup and to calculate pulse durations at the sample position. Our simulations show that electron bunches containing few thousands of electrons per bunch are only weakly broadened by space-charge effects and their pulse duration is thus close to the one of a single-electron wavepacket. With our compact setup, we can create electron bunches containing up to 5000 electrons with a pulse duration below 100 fs on the sample. We use the diffractometer to track the energy transfer from photoexcited electrons to the lattice in a thin film of titanium. This process takes place on the timescale of few-hundred femtoseconds and a fully equilibrated state is reached within 1 ps

Electron backscattering for process control in electron beam welding

International Nuclear Information System (INIS)

Ardenne, T. von; Panzer, S.

1983-01-01

A number of solutions to the automation of electron beam welding is presented. On the basis of electron backscattering a complex system of process control has been developed. It allows an enlarged imaging of the material's surface, improved adjustment of the beam focusing and definite focus positioning. Furthermore, both manual and automated positioning of the electron beam before and during the welding process has become possible. Monitoring of the welding process for meeting standard welding requirements can be achieved with the aid of a control quantity derived from the results of electronic evaluation of the high-frequency electron backscattering

Electron transfer reactions

CERN Document Server

Cannon, R D

2013-01-01

Electron Transfer Reactions deals with the mechanisms of electron transfer reactions between metal ions in solution, as well as the electron exchange between atoms or molecules in either the gaseous or solid state. The book is divided into three parts. Part 1 covers the electron transfer between atoms and molecules in the gas state. Part 2 tackles the reaction paths of oxidation states and binuclear intermediates, as well as the mechanisms of electron transfer. Part 3 discusses the theories and models of the electron transfer process; theories and experiments involving bridged electron transfe

Understand electronics

CERN Document Server

Bishop, Owen

2013-01-01

Understand Electronics provides a readable introduction to the exciting world of electronics for the student or enthusiast with little previous knowledge. The subject is treated with the minimum of mathematics and the book is extensively illustrated.This is an essential guide for the newcomer to electronics, and replaces the author's best-selling Beginner's Guide to Electronics.The step-by-step approach makes this book ideal for introductory courses such as the Intermediate GNVQ.

Electronic Commerce

OpenAIRE

Slavko Đerić

2016-01-01

Electronic commerce can be defined in different ways. Any definition helps to understand and explain that concept as better as possible.. Electronic commerce is a set of procedures and technologies that automate the tasks of financial transactions using electronic means. Also, according to some authors, electronic commerce is defined as a new concept, which is being developed and which includes process of buying and selling or exchanging products, services or information via computer networks...

Photon and electron collimator effects on electron output and abutting segments in energy modulated electron therapy

International Nuclear Information System (INIS)

Olofsson, Lennart; Karlsson, Magnus G.; Karlsson, Mikael

2005-01-01

In energy modulated electron therapy a large fraction of the segments will be arranged as abutting segments where inhomogeneities in segment matching regions must be kept as small as possible. Furthermore, the output variation between different segments should be minimized and must in all cases be well predicted. For electron therapy with add-on collimators, both the electron MLC (eMLC) and the photon MLC (xMLC) contribute to these effects when an xMLC tracking technique is utilized to reduce the x-ray induced leakage. Two add-on electron collimator geometries have been analyzed using Monte Carlo simulations: One isocentric eMLC geometry with an isocentric clearance of 35 cm and air or helium in the treatment head, and one conventional proximity geometry with a clearance of 5 cm and air in the treatment head. The electron fluence output for 22.5 MeV electrons is not significantly affected by the xMLC if the shielding margins are larger than 2-3 cm. For small field sizes and 9.6 MeV electrons, the isocentric design with helium in the treatment head or shielding margins larger than 3 cm is needed to avoid a reduced electron output. Dose inhomogeneity in the matching region of electron segments is, in general, small when collimator positions are adjusted to account for divergence in the field. The effect of xMLC tracking on the electron output can be made negligible while still obtaining a substantially reduced x-ray leakage contribution. Collimator scattering effects do not interfere significantly when abutting beam techniques are properly applied

Equation satisfied by electron-electron mutual Coulomb repulsion energy density functional

OpenAIRE

Joubert, Daniel P.

2011-01-01

The electron-electron mutual Coulomb repulsion energy density functional satisfies an equation that links functionals and functional derivatives at N-electron and (N-1)-electron densities for densities determined from the same adiabatic scaled external potential for the N-electron system.

Electronic Publishing.

Science.gov (United States)

Lancaster, F. W.

1989-01-01

Describes various stages involved in the applications of electronic media to the publishing industry. Highlights include computer typesetting, or photocomposition; machine-readable databases; the distribution of publications in electronic form; computer conferencing and electronic mail; collaborative authorship; hypertext; hypermedia publications;…

Syringe-injectable electronics.

Science.gov (United States)

Liu, Jia; Fu, Tian-Ming; Cheng, Zengguang; Hong, Guosong; Zhou, Tao; Jin, Lihua; Duvvuri, Madhavi; Jiang, Zhe; Kruskal, Peter; Xie, Chong; Suo, Zhigang; Fang, Ying; Lieber, Charles M

2015-07-01

Seamless and minimally invasive three-dimensional interpenetration of electronics within artificial or natural structures could allow for continuous monitoring and manipulation of their properties. Flexible electronics provide a means for conforming electronics to non-planar surfaces, yet targeted delivery of flexible electronics to internal regions remains difficult. Here, we overcome this challenge by demonstrating the syringe injection (and subsequent unfolding) of sub-micrometre-thick, centimetre-scale macroporous mesh electronics through needles with a diameter as small as 100 μm. Our results show that electronic components can be injected into man-made and biological cavities, as well as dense gels and tissue, with >90% device yield. We demonstrate several applications of syringe-injectable electronics as a general approach for interpenetrating flexible electronics with three-dimensional structures, including (1) monitoring internal mechanical strains in polymer cavities, (2) tight integration and low chronic immunoreactivity with several distinct regions of the brain, and (3) in vivo multiplexed neural recording. Moreover, syringe injection enables the delivery of flexible electronics through a rigid shell, the delivery of large-volume flexible electronics that can fill internal cavities, and co-injection of electronics with other materials into host structures, opening up unique applications for flexible electronics.

Electronic excitation of Na atom by electron impact

International Nuclear Information System (INIS)

Bielschowsky, C.E.; Souza, G.G.B. de; Lucas, C.A.; Nogueira, J.C.

1988-01-01

Electronic excitation of the 3s-3p transition in the Na atom was studied by intermediate energy electron impact spectroscopy. Differential Cross Sections (DCS) and Generalized Oscillator Strenghts (GOS) were determined experimentally for 1 KeV electrons. Theoretical results within the First Born Approximation as well as Glauber theory, were also performed. (A.C.A.S.) [pt

Highly efficient electron gun with a single-atom electron source

International Nuclear Information System (INIS)

Ishikawa, Tsuyoshi; Urata, Tomohiro; Cho, Boklae; Rokuta, Eiji; Oshima, Chuhei; Terui, Yoshinori; Saito, Hidekazu; Yonezawa, Akira; Tsong, Tien T.

2007-01-01

The authors have demonstrated highly collimated electron-beam emission from a practical electron gun with a single-atom electron source; ∼80% of the total emission current entered the electron optics. This ratio was two or three orders of magnitude higher than those of the conventional electron sources such as a cold field emission gun and a Zr/O/W Schottky gun. At the pressure of less than 1x10 -9 Pa, the authors observed stable emission of 20 nA, which generates the specimen current of 5 pA required for scanning electron microscopes

Electron-electron interaction in p-SiGe/Ge quantum wells

International Nuclear Information System (INIS)

Roessner, Benjamin; Kaenel, Hans von; Chrastina, Daniel; Isella, Giovanni; Batlogg, Bertram

2005-01-01

The temperature dependent magnetoresistance of high mobility p-SiGe/Ge quantum wells is studied with hole densities ranging from 1.7 to 5.9 x 10 11 cm -2 . At magnetic fields below the onset of quantum oscillations that reflect the high mobility values (up to 75000 cm 2 /Vs), we observe the clear signatures of electron-electron interaction. We compare our experiment with the theory of electron-electron interaction including the Zeeman band splitting. The observed magnetoresistance is well explained as a superposition of band structure induced positive magnetoresistance and the negative magntoresistance due to the electron-electron interaction effect

Electron-electron interactions in disordered systems

CERN Document Server

Efros, AL

1985-01-01

``Electron-Electron Interactions in Disordered Systems'' deals with the interplay of disorder and the Coulomb interaction. Prominent experts give state-of-the-art reviews of the theoretical and experimental work in this field and make it clear that the interplay of the two effects is essential, especially in low-dimensional systems.

Narrow electron injector for ballistic electron spectroscopy

International Nuclear Information System (INIS)

Kast, M.; Pacher, C.; Strasser, G.; Gornik, E.

2001-01-01

A three-terminal hot electron transistor is used to measure the normal energy distribution of ballistic electrons generated by an electron injector utilizing an improved injector design. A triple barrier resonant tunneling diode with a rectangular transmission function acts as a narrow (1 meV) energy filter. An asymmetric energy distribution with its maximum on the high-energy side with a full width at half maximum of ΔE inj =10 meV is derived. [copyright] 2001 American Institute of Physics

Temperature Dependence of the Spin-Hall Conductivity of a Two-Dimensional Impure Rashba Electron Gas in the Presence of Electron-Phonon and Electron-Electron Interactions

Science.gov (United States)

Yavari, H.; Mokhtari, M.; Bayervand, A.

2015-03-01

Based on Kubo's linear response formalism, temperature dependence of the spin-Hall conductivity of a two-dimensional impure (magnetic and nonmagnetic impurities) Rashba electron gas in the presence of electron-electron and electron-phonon interactions is analyzed theoretically. We will show that the temperature dependence of the spin-Hall conductivity is determined by the relaxation rates due to these interactions. At low temperature, the elastic lifetimes ( and are determined by magnetic and nonmagnetic impurity concentrations which are independent of the temperature, while the inelastic lifetimes ( and related to the electron-electron and electron-phonon interactions, decrease when the temperature increases. We will also show that since the spin-Hall conductivity is sensitive to temperature, we can distinguish the intrinsic and extrinsic contributions.

Analytical local electron-electron interaction model potentials for atoms

International Nuclear Information System (INIS)

Neugebauer, Johannes; Reiher, Markus; Hinze, Juergen

2002-01-01

Analytical local potentials for modeling the electron-electron interaction in an atom reduce significantly the computational effort in electronic structure calculations. The development of such potentials has a long history, but some promising ideas have not yet been taken into account for further improvements. We determine a local electron-electron interaction potential akin to those suggested by Green et al. [Phys. Rev. 184, 1 (1969)], which are widely used in atom-ion scattering calculations, electron-capture processes, and electronic structure calculations. Generalized Yukawa-type model potentials are introduced. This leads, however, to shell-dependent local potentials, because the origin behavior of such potentials is different for different shells as has been explicated analytically [J. Neugebauer, M. Reiher, and J. Hinze, Phys. Rev. A 65, 032518 (2002)]. It is found that the parameters that characterize these local potentials can be interpolated and extrapolated reliably for different nuclear charges and different numbers of electrons. The analytical behavior of the corresponding localized Hartree-Fock potentials at the origin and at long distances is utilized in order to reduce the number of fit parameters. It turns out that the shell-dependent form of Green's potential, which we also derive, yields results of comparable accuracy using only one shell-dependent parameter

Extracting electron backscattering coefficients from backscattered electron micrographs

International Nuclear Information System (INIS)

Zupanic, F.

2010-01-01

Electron backscattering micrographs possess the so-called Z-contrast, carrying information about the chemical compositions of phases present in microstructures. The intensity at a particular point in the backscattered electron micrograph is proportional to the signal detected at a corresponding point in the scan raster, which is, in turn, proportional to the electron backscattering coefficient of a phase at that point. This article introduces a simple method for extracting the electron backscattering coefficients of phases present in the microstructure, from the backscattered electron micrographs. This method is able to convert the micrograph's greyscale to the backscattering-coefficient-scale. The prerequisite involves the known backscattering coefficients for two phases in the micrograph. In this way, backscattering coefficients of other phases can be determined. The method is unable to determine the chemical compositions of phases or the presence of an element only from analysing the backscattered electron micrograph. Nevertheless, this method was found to be very powerful when combined with energy dispersive spectroscopy, and the calculations of backscattering coefficients. - Research Highlights: →A simple method for extracting the electron backscattering coefficients →The prerequisite is known backscattering coefficients for two phases →The information is complementary to the EDS-results. →This method is especially useful when a phase contains a light element (H, Li, Be, and B)

PIC simulation of the electron-ion collision effects on suprathermal electrons

International Nuclear Information System (INIS)

Wu Yanqing; Han Shensheng

2000-01-01

The generation and transportation of suprathermal electrons are important to both traditional ICF scheme and 'Fast Ignition' scheme. The author discusses the effects of electron-ion collision on the generation and transportation of the suprathermal electrons by parametric instability. It indicates that the weak electron-ion term in the PIC simulation results in the enhancement of the collisional absorption and increase of the hot electron temperature and reduction in the maximum electrostatic field amplitude while wave breaking. Therefore the energy and distribution of the suprathermal electrons are changed. They are distributed more close to the phase velocity of the electrostatic wave than the case without electron-ion collision term. The electron-ion collision enhances the self-consistent field and impedes the suprathermal electron transportation. These factors also reduce the suprathermal electron energy. In addition, the authors discuss the effect of initial condition on PIC simulation to ensure that the results are correct

Spin Relaxation in GaAs: Importance of Electron-Electron Interactions

Directory of Open Access Journals (Sweden)

Gionni Marchetti

2014-04-01

Full Text Available We study spin relaxation in n-type bulk GaAs, due to the Dyakonov–Perel mechanism, using ensemble Monte Carlo methods. Our results confirm that spin relaxation time increases with the electronic density in the regime of moderate electronic concentrations and high temperature. We show that the electron-electron scattering in the non-degenerate regime significantly slows down spin relaxation. This result supports predictions by Glazov and Ivchenko. Most importantly, our findings highlight the importance of many-body interactions for spin dynamics: we show that only by properly taking into account electron-electron interactions within the simulations, results for the spin relaxation time—with respect to both electron density and temperature—will reach good quantitative agreement with corresponding experimental data. Our calculations contain no fitting parameters.

Secondary mineralization in carious lesions of human dentin. Electron-probe, electron microscope, and electron diffraction studies

Energy Technology Data Exchange (ETDEWEB)

Ogiwara, H [Tokyo Dental Coll. (Japan)

1975-02-01

Dentinal carious lesions having a remineralized surface layer were studied by means electron-probe microanalysis, electron microscopy, electron diffraction. As the results of electron-probe study, F, Mg, and Na were found to be distributed mainly in the remineralized surface layer and S in the decalcified region where decreases in Ca, P, and Mg concentration were usually observed. The decrease in Mg concentration always started earlier than that of Ca and P concentration. Electron microscope and electron diffraction studies revealed that apatic crystals in the remineralized surface layer were much larger than those in the intact dentin. Although they were less conspicuous, crystals in the decalcified region also were larger than those in the intact region. Dentinal tubules, occluded by many crystals, were frequently seen during the observations. Crystals in the tubules varied in morphology, showing granular, needle, rhomboid, and tabular shapes. By means of electron diffraction, the granular- or needle-shaped crystals were identified as apatite and the rhomboid-shaped crystals as whitlockite. Some of the tabular-shaped crystals appeared to be cotacalcium phosphate.

Electronic components

CERN Document Server

Colwell, Morris A

1976-01-01

Electronic Components provides a basic grounding in the practical aspects of using and selecting electronics components. The book describes the basic requirements needed to start practical work on electronic equipment, resistors and potentiometers, capacitance, and inductors and transformers. The text discusses semiconductor devices such as diodes, thyristors and triacs, transistors and heat sinks, logic and linear integrated circuits (I.C.s) and electromechanical devices. Common abbreviations applied to components are provided. Constructors and electronics engineers will find the book useful

Ion- and electron-acoustic solitons in two-electron temperature space plasmas

International Nuclear Information System (INIS)

Lakhina, G. S.; Kakad, A. P.; Singh, S. V.; Verheest, F.

2008-01-01

Properties of ion- and electron-acoustic solitons are investigated in an unmagnetized multicomponent plasma system consisting of cold and hot electrons and hot ions using the Sagdeev pseudopotential technique. The analysis is based on fluid equations and the Poisson equation. Solitary wave solutions are found when the Mach numbers exceed some critical values. The critical Mach numbers for the ion-acoustic solitons are found to be smaller than those for electron-acoustic solitons for a given set of plasma parameters. The critical Mach numbers of ion-acoustic solitons increase with the increase of hot electron temperature and the decrease of cold electron density. On the other hand, the critical Mach numbers of electron-acoustic solitons increase with the increase of the cold electron density as well as the hot electron temperature. The ion-acoustic solitons have positive potentials for the parameters considered. However, the electron-acoustic solitons have positive or negative potentials depending whether the fractional cold electron density with respect to the ion density is greater or less than a certain critical value. Further, the amplitudes of both the ion- and electron-acoustic solitons increase with the increase of the hot electron temperature. Possible application of this model to electrostatic solitary waves observed on the auroral field lines by the Viking spacecraft is discussed

Diffusive scattering of electrons by electron holes around injection fronts

Science.gov (United States)

Vasko, I. Y.; Agapitov, O. V.; Mozer, F. S.; Artemyev, A. V.; Krasnoselskikh, V. V.; Bonnell, J. W.

2017-03-01

Van Allen Probes have detected nonlinear electrostatic spikes around injection fronts in the outer radiation belt. These spikes include electron holes (EH), double layers, and more complicated solitary waves. We show that EHs can efficiently scatter electrons due to their substantial transverse electric fields. Although the electron scattering driven by EHs is diffusive, it cannot be evaluated via the standard quasi-linear theory. We derive analytical formulas describing local electron scattering by a single EH and verify them via test particle simulations. We show that the most efficiently scattered are gyroresonant electrons (crossing EH on a time scale comparable to the local electron gyroperiod). We compute bounce-averaged diffusion coefficients and demonstrate their dependence on the EH spatial distribution (latitudinal extent and spatial filling factor) and individual EH parameters (amplitude of electrostatic potential, velocity, and spatial scales). We show that EHs can drive pitch angle scattering of ≲5 keV electrons at rates 10-2-10-4 s-1 and, hence, can contribute to electron losses and conjugated diffuse aurora brightenings. The momentum and pitch angle scattering rates can be comparable, so that EHs can also provide efficient electron heating. The scattering rates driven by EHs at L shells L ˜ 5-8 are comparable to those due to chorus waves and may exceed those due to electron cyclotron harmonics.

Pseudogap in the Eliashberg approach based on electron-phonon and electron-electron-phonon interaction

Energy Technology Data Exchange (ETDEWEB)

Szczesniak, R. [Institute of Physics, Czestochowa University of Technology (Poland); Institute of Physics, Jan Dlugosz University in Czestochowa (Poland); Durajski, A.P.; Duda, A.M. [Institute of Physics, Czestochowa University of Technology (Poland)

2017-04-15

The properties of the superconducting and the anomalous normal state were described by using the Eliashberg method. The pairing mechanism was reproduced with the help of the Hamiltonian, which models the electron-phonon and the electron-electron-phonon interaction (EEPh). The set of the Eliashberg equations, which determines the order parameter function (φ), the wave function renormalization factor (Z), and the energy shift function (χ), was derived. It was proven that for the sufficiently large values of the EEPh potential, the doping dependence of the order parameter (φ/Z) has the analogous course to that observed experimentally in cuprates. The energy gap in the electron density of states is induced by Z and χ - the contribution from φ is negligible. The electron density of states possesses the characteristic asymmetric form and the pseudogap is observed above the critical temperature. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Carbon Nanotube Electron Gun

Science.gov (United States)

Nguyen, Cattien V. (Inventor); Ribaya, Bryan P. (Inventor)

2013-01-01

An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

Molecular electron affinities

International Nuclear Information System (INIS)

Fukuda, E.K.

1983-01-01

Molecular electron affinities have historically been difficult quantities to measure accurately. These difficulties arise from differences in structure between the ion and neutral as well as the existence of excited negative ion states. To circumvent these problems, relative electron affinities were determined in this dissertation by studying equilibrium electron transfer reactions using a pulsed ion cyclotron resonance (ICR) spectrometer. Direct measurement of ion and neutral concentrations for reactions of the general type, A - + B = B - + A, allow calculation of the equilibrium constant and, therefore, the free energy change. The free energy difference is related to the difference in electron affinities between A and B. A relative electron affinity scale covering a range of about 45 kcal/mol was constructed with various substituted p-benzoquinones, nitrobenzenes, anhydrides, and benzophenones. To assign absolute electron affinities, various species with accurately known electron affinities are tied to the scale via ion-cyclotron double resonance bracketing techniques. After the relative scale is anchored to these species with well-known electron affinities, the scale is then used as a check on other electron affinity values as well as generating new electron affinity values. Many discrepancies were found between the electron affinities measured using the ICR technique and previous literature determinations

Nonambipolar electron source

International Nuclear Information System (INIS)

Longmier, B.; Baalrud, S.; Hershkowitz, N.

2006-01-01

A radio frequency (rf) plasma-based electron source that does not rely on electron emission at a cathode surface has been constructed. All of the random electron flux incident on an exit aperture is extracted through an electron sheath resulting in total nonambipolar flow within the device when the ratio of the ion loss area to the electron loss area is approximately equal to the square root of the ratio of the ion mass to the electron mass, and the ion sheath potential drop at the chamber walls is much larger than T e /e. The nonambipolar electron source (NES) has an axisymmetric magnetic field of 100 G at the extraction aperture that results in a uniform plasma potential across the aperture, allowing the extraction of all the incident electron flux without the use of grids. A prototype NES has produced 15 A of continuous electron current, using 15 SCCM (SCCM denotes cubic centimeter per minute at STP) Ar, 1200 W rf power at 13.56 MHz, and 6 times gas utilization. Alternatively 8 A of electron current can be produced, using 3 SCCM Ar at 1200 W rf and 20 times gas utilization. NES could replace hollow cathode electron sources in a wide variety of applications

Electron-plasmon model in the electron liquid theory

Directory of Open Access Journals (Sweden)

M.V.Vavrukh

2005-01-01

Full Text Available Here we propose an accurate approach to the description of the electron liquid model in the electron and plasmon terms. Our ideas in the present paper are close to the conception of the collective variables which was developed in the papers of Bohm and Pines. However we use another body of mathematics in the transition to the expanded space of variable particles and plasmons realized by the transition operator. It is evident that in the Random Phase Approximation (RPA, the model which consists of two interactive subsystems of electrons and plasmons is equivalent to the electron liquid model with Coulomb interaction.

Polymer electronics

CERN Document Server

Hsin-Fei, Meng

2013-01-01

Polymer semiconductor is the only semiconductor that can be processed in solution. Electronics made by these flexible materials have many advantages such as large-area solution process, low cost, and high performance. Researchers and companies are increasingly dedicating time and money in polymer electronics. This book focuses on the fundamental materials and device physics of polymer electronics. It describes polymer light-emitting diodes, polymer field-effect transistors, organic vertical transistors, polymer solar cells, and many applications based on polymer electronics. The book also disc

A direct electron detector for time-resolved MeV electron microscopy

Energy Technology Data Exchange (ETDEWEB)

Vecchione, T.; Denes, P.; Jobe, R. K.; Johnson, I. J.; Joseph, J. M.; Li, R. K.; Perazzo, A.; Shen, X.; Wang, X. J.; Weathersby, S. P.; Yang, J.; Zhang, D.

2017-03-01

The introduction of direct electron detectors enabled the structural biology revolution of cryogenic electron microscopy. Direct electron detectors are now expected to have a similarly dramatic impact on time-resolved MeV electron microscopy, particularly by enabling both spatial and temporal jitter correction. Here we report on the commissioning of a direct electron detector for time-resolved MeV electron microscopy. The direct electron detector demonstrated MeV single electron sensitivity and is capable of recording megapixel images at 180 Hz. The detector has a 15-bit dynamic range, better than 30-μmμm spatial resolution and less than 20 analogue-to-digital converter count RMS pixel noise. The unique capabilities of the direct electron detector and the data analysis required to take advantage of these capabilities are presented. The technical challenges associated with generating and processing large amounts of data are also discussed.

Coherent Electron Focussing in a Two-Dimensional Electron Gas.

NARCIS (Netherlands)

Houten, H. van; Wees, B.J. van; Mooij, J.E.; Beenakker, C.W.J.; Williamson, J.G.; Foxon, C.T.

1988-01-01

The first experimental realization of ballistic point contacts in a two-dimensional electron gas for the study of transverse electron focussing by a magnetic field is reported. Multiple peaks associated with skipping orbits of electrons reflected specularly by the channel boundary are observed. At

A study on the secondary electrons in a clinical electron beam

International Nuclear Information System (INIS)

Krithivas, G.; Rao, S.N.

1989-01-01

The central axis dose of a 12 MeV clinical electron beam is investigated in terms of an axial component due to primary electrons in the central ray and a lateral component due to secondary electrons originating from multiple scattering of electrons in the off-axis rays. To this effect secondary electron fluence measurements in a polystyrene medium irradiated with a collimated beam are made with a sensitive diode detector. This leads to a construction of secondary electron depth-dose profiles for beam sizes of diameters ranging from 1.7 to 17.4 cm. The results indicate that the lateral electrons account for 25% of the dose in the therapeutic region. For these electrons, the depth of dose maximum is correlated with diffusion depth and maximum lateral excursion in the medium. Dose component due to backscatter electrons at depths is also investigated using a thin-window parallel-plate ion chamber. The role of lateral and backscatter electrons in characterising central axis per cent depth-dose is discussed. (author)

Electronics for dummies

CERN Document Server

Shamieh

2015-01-01

Explore the basic concepts of electronics, build your electronics workbench, and begin creating fun electronics projects right away! Electronics For Dummies, 3rd Edition is your guide to the world of electronics. Spanning circuitry, wiring, robotics, transmitters, amplifiers, and more, this book demystifies electricity basics and beyond. The third edition offers new content revised to reflect the latest advancements in the electronics field, and it offers full color project examples to spark your creativity and inspire you to put your new skills to use! Packed with projects that can be comple

Electron holography

CERN Document Server

Tonomura, Akira

1993-01-01

Holography was devised for breaking through the resolution limit of electron microscopes The advent of a "coherent" field emission electron beam has enabled the use of Electron Holography in various areas of magnetic domain structures observation, fluxon observation in superconductors, and fundamental experiments in physics which have been inaccessible using other techniques After examining the fundamentals of electron holography and its applications to the afore mentioned fields, a detailed discussion of the Aharonov-Bohm effect and the related experiments is presented Many photographs and illustrations are included to elucidate the text

Comprehensive analysis of electron correlations in three-electron atoms

International Nuclear Information System (INIS)

Morishita, T.; Lin, C.D.

1999-01-01

We study the electron correlations in singly, doubly, and triply excited states of a three-electron atom. While electron correlation in general is weak for singly excited states, correlation plays major roles in determining the characteristics of doubly and triply excited states. Using the adiabatic approximation in hyperspherical coordinates, we show that the distinction between singly, doubly, and triply excited states is determined by the radial correlations, while finer distinctions within doubly or triply excited states lie in the angular correlations. Partial projections of the body-fixed frame wave functions are used to demonstrate the characteristic nodal surfaces which provide clues to the energy ordering of the states. We show that doubly excited states of a three-electron atom exhibit correlations that are similar to the doubly excited states of a two-electron atom. For the triply excited states, we show that the motion of the three electrons resemble approximately that of a symmetric top. copyright 1999 The American Physical Society

Advanced electron beam techniques

International Nuclear Information System (INIS)

Hirotsu, Yoshihiko; Yoshida, Yoichi

2007-01-01

After 100 years from the time of discovery of electron, we now have many applications of electron beam in science and technology. In this report, we review two important applications of electron beam: electron microscopy and pulsed-electron beam. Advanced electron microscopy techniques to investigate atomic and electronic structures, and pulsed-electron beam for investigating time-resolved structural change are described. (author)

Effects of electron-electron interactions on electronic transport in disordered systems

International Nuclear Information System (INIS)

Foley, Simon Timothy

2002-01-01

This thesis is concerned with the role of electron-electron interactions on electronic transport in disordered systems. We first consider a novel non-linear sigma model in order to microscopically treat the effects of disorder and electronic interaction. We successfully reproduce the perturbative results for the zero-bias anomaly and the interaction correction to the conductivity in a weakly disordered system, and discuss possible directions for future work. Secondly we consider the fluctuations of the dephasing rate for a closed diffusive and quantum dot system. Using the Keldysh technique we derive an expression for the inelastic scattering rate with which we self-consistently obtain the fluctuations in the dephasing rate. For the diffusive regime we find the relative fluctuations is given by F ∼ (L φ /L) 2 /g 2 , where g is the dimensionless conductance, L φ is the dephasing length and L is the sample size. For the quantum dot regime we find a perturbative divergence due to the presence of the zero mode. By mapping divergent diagrams to those for the two-level correlation function, we conjecture the existence of an exact relation between the two. Finally we discuss the consequences of this relation. (author)

Calidad de las accesiones colectadas en la región centro-oriental de Cuba (Nota técnica Quality of accessions collected in the central-eastern region of Cuba (Technical note

Directory of Open Access Journals (Sweden)

J Reino

2010-06-01

Full Text Available Se efectuó una prospección en el 2005, en la región centro-oriental de Cuba, y se colectaron semillas de 43 accesiones (36 de leguminosas arbóreas y siete de herbáceas. Posteriormente se realizó una prueba de germinación para conocer la calidad de las semillas (con corte de cubierta, en placas de petri sobre arena de río. El número de semillas utilizadas en cada accesión fue diferente (según las colectadas y solo se empleó una réplica (sin diseño estadístico. Las semillas de mejor calidad correspondieron a las accesiones Bauhinia acuminata, Bauhinia purpurea (de Nuevitas y Vertientes, Cassia fistula, Albizia kalkora, Centrosema sp. y Centrosema brasilianum (100% de germinación, así como Calopogonium caeruleum (90% y Albizia lucida (91,6%. Siete accesiones no germinaron. La mayoría logró una alta sobrevivencia (en bolsas, aunque en especies como Bauhinia hookeli, B. acuminata, Albizia lebbeck, C. caeruleum, C. brasilianum, Desmodium sp. y Teramnus sp. fue baja y dos accesiones no sobrevivieron. El germoplasma de la EEPF «Indio Hatuey» se incrementó en 34 accesiones. Se demostró la importancia de conocer la calidad de las semillas y la relación entre este indicador y su deterioro, debido a la gran variabilidad que mostró el porcentaje de germinación en semillas colectadas en un mismo período de tiempo.A prospection was made in 2005, in the central-eastern region of Cuba and seeds from 43 accessions (36 tree legumes and seven herbaceous ones were collected. Afterwards, a germination test was conducted in order to learn the quality of the seeds (with seed coat cut, in Petri dishes on river sand. The number of seeds used in each accession was different (according to the collected ones and only one replication was used (without statistical design. The best-quality seeds corresponded to the accessions Bauhinia acuminata, Bauhinia purpurea (from Nuevitas and Vertientes, Cassia fistula, Albizia kalkora, Centrosema sp. and

Characteristics of trapped electrons and electron traps in single crystals

International Nuclear Information System (INIS)

Budzinski, E.E.; Potter, W.R.; Potienko, G.; Box, H.C.

1979-01-01

Two additional carbohydrates are reported whose crystal structures trap electrons intermolecularly in single crystals x irradiated at low temperature, namely sucrose and rhamnose. Five carbohydrate and polyhydroxy compounds are now known which exhibit this phenomenon. The following characteristics of the phenomenon were investigated: (1) the hyperfine couplings of the electron with protons of the polarized hydroxy groups forming the trap; (2) the distances between these protons and the trapped electron; (3) the spin density of the electron at the protons and (4) the relative stabilities of the electron trapped in various crystal structures

Electron-electron scattering in linear transport in two-dimensional systems

DEFF Research Database (Denmark)

Hu, Ben Yu-Kuang; Flensberg, Karsten

1996-01-01

We describe a method for numerically incorporating electron-electron scattering in quantum wells for small deviations of the distribution function from equilibrium, within the framework of the Boltzmann equation. For a given temperature T and density n, a symmetric matrix needs to be evaluated only...... once, and henceforth it can be used to describe electron-electron scattering in any Boltzmann equation linear-response calculation for that particular T and n. Using this method, we calculate the distribution function and mobility for electrons in a quantum well, including full finite...

Terahertz Plasma Waves in Two Dimensional Quantum Electron Gas with Electron Scattering

International Nuclear Information System (INIS)

Zhang Liping

2015-01-01

We investigate the Terahertz (THz) plasma waves in a two-dimensional (2D) electron gas in a nanometer field effect transistor (FET) with quantum effects, the electron scattering, the thermal motion of electrons and electron exchange-correlation. We find that, while the electron scattering, the wave number along y direction and the electron exchange-correlation suppress the radiation power, but the thermal motion of electrons and the quantum effects can amplify the radiation power. The radiation frequency decreases with electron exchange-correlation contributions, but increases with quantum effects, the wave number along y direction and thermal motion of electrons. It is worth mentioning that the electron scattering has scarce influence on the radiation frequency. These properties could be of great help to the realization of practical THz plasma oscillations in nanometer FET. (paper)

Oblique electron cyclotron emission for electron distribution studies (invited)

International Nuclear Information System (INIS)

Preische, S.; Efthimion, P.C.; Kaye, S.M.

1997-01-01

Electron cyclotron emission (ECE) at an oblique angle to the magnetic field provides a means of probing the electron distribution function both in energy and physical space through changes in and constraints on the relativistic electron cyclotron resonance condition. Diagnostics based on this Doppler shifted resonance are able to study a variety of electron distributions through changes in the location of the resonance in physical or energy space accomplished by changes in the viewing angle and frequency, and the magnetic field. For the case of observation across a changing magnetic field, such as across the tokamak midplane, the constraint on the resonance condition for real solutions to the dispersion relation can constrain the physical location of optically thin emission. A new Oblique ECE diagnostic was installed and operated on the PBX-M tokamak for the study of energetic electrons during lower hybrid current drive. It has a view 33 degree with respect to perpendicular in the tokamak midplane, receives second harmonic X-mode emission, and is constrained to receive single pass emission by SiC viewing dumps on the tokamak walls. Spatial localization of optically thin emission from superthermal electrons (50 endash 100 keV) was obtained by observation of emission upshifted from a thermal cyclotron harmonic. The localized measurements of the electron energy distribution and the superthermal density profile made by this diagnostic demonstrate its potential to study the spatial transport of energetic electrons on fast magnetohydrodynamic time scales or anomalous diffusion time scales. Oblique ECE can also be used to study electron distributions that may have a slight deviation from a Maxwellian by localizing the emission in energy space. (Abstract Truncated)

Electron microscopy of boron carbide before and after electron irradiation

International Nuclear Information System (INIS)

Stoto, T.; Zuppiroli, L.; Beauvy, M.; Athanassiadis, T.

1984-06-01

The microstructure of boron carbide has been studied by electron microscopy and related to the composition of the material. After electron irradiations in an usual transmission electron microscope and in a high voltage electron microscope at different temperatures and fluxes no change of these microstructures have been observed but a sputtering of the surface of the samples, which has been studied quantitatively [fr

Electron Cyclotron Resonances in Electron Cloud Dynamics

International Nuclear Information System (INIS)

Celata, Christine; Celata, C.M.; Furman, Miguel A.; Vay, J.-L.; Yu, Jennifer W.

2008-01-01

We report a previously unknown resonance for electron cloud dynamics. The 2D simulation code 'POSINST' was used to study the electron cloud buildup at different z positions in the International Linear Collider positron damping ring wiggler. An electron equilibrium density enhancement of up to a factor of 3 was found at magnetic field values for which the bunch frequency is an integral multiple of the electron cyclotron frequency. At low magnetic fields the effects of the resonance are prominent, but when B exceeds ∼(2 pi mec/(elb)), with lb = bunch length, effects of the resonance disappear. Thus short bunches and low B fields are required for observing the effect. The reason for the B field dependence, an explanation of the dynamics, and the results of the 2D simulations and of a single-particle tracking code used to elucidate details of the dynamics are discussed

Role of electron-electron interactions in the RKKY theory of magnetism

International Nuclear Information System (INIS)

Cooke, J.F.

1978-10-01

The theory of magnetism in heavy rare earth metals is based on the RKKY theory. In this formalism the indirect exchange interaction between the local 4f spins is mediated by the conduction electrons. When carried to second order in the 4f-conduction electron interaction, traditional perturbation theory leads to a Heisenberg-like interaction between the local spins which depends on the electronic energy bands and 4f-conduction electron exchange matrix elements. This derivation neglects the detailed behavior of electron-electron interaction within the conduction band, which is known to be important in metallic systems. By using an equation of motion method, an expression for the inelastic neutron scattering cross-section has been derived which includes, in an approximate way, this electron-electron interaction. The results of this calculation indicate that spin-wave peaks can be broadened and shifted if the spin-wave band lies near the conduction electron Stoner continuum. The origin of this effect is similar to that found in itinerant electron systems where the spin-wave band actually intersects the Stoner continuum, resulting in the disappearance of the spin-wave mode

Role of electron-electron interactions in the RKKY theory of magnetism

International Nuclear Information System (INIS)

Cooke, J.F.

1979-01-01

The theory of magnetism in heavy rare earth metals is based on the RKKY theory. In this formalism the indirect exchange interaction between the local 4f spins is mediated by the conduction electrons. When carried to second order in the 4f-conduction electron interaction, traditional pertubation theory leads to a Heisenberg-like interaction between the local spins which depends on the electronic energy bands and 4f-conduction electron exchange matrix elements. This derivation neglects the detailed behavior of electron-electron interaction within the conduction band, which is known to be important in metallic systems. By using an equation of motion method, an expression for the inelastic neutron scattering cross-section has been derived which includes, in an approximate way, this electron-electron interaction. The results of this calculation indicate that spin-wave peaks can be broadened and shifted if the spin-wave band lies near the conduction electron Stoner continuum. The origin of this effect is similar to that found in itinerant electron systems where the spin-wave band actually intersects the Stoner continuum, resulting in the disappearance of the spin-wave mode

Electron acoustic solitary waves in unmagnetized two electron population dense plasmas

International Nuclear Information System (INIS)

Mahmood, S.; Masood, W.

2008-01-01

The electron acoustic solitary waves are studied in unmagnetized two population electron quantum plasmas. The quantum hydrodynamic model is employed with the Sagdeev potential approach to describe the arbitrary amplitude electron acoustic waves in a two electron population dense Fermi plasma. It is found that hot electron density hump structures are formed in the subsonic region in such type of quantum plasmas. The wave amplitude as well as the width of the soliton are increased with the increase of percentage presence of cold (thinly populated) electrons in a multicomponent quantum plasma. It is found that an increase in quantum diffraction parameter broadens the nonlinear structure. Furthermore, the amplitude of the nonlinear electron acoustic wave is found to increase with the decrease in Mach number. The numerical results are also presented to understand the formation of solitons in two electron population Fermi plasmas.

Advances in imaging and electron physics the scanning transmission electron microscope

CERN Document Server

Hawkes, Peter W

2009-01-01

Advances in Imaging and Electron Physics merges two long-running serials--Advances in Electronics and Electron Physics and Advances in Optical and Electron Microscopy. This series features extended articles on the physics of electron devices (especially semiconductor devices), particle optics at high and low energies, microlithography, image science and digital image processing, electromagnetic wave propagation, electron microscopy, and the computing methods used in all these domains.  This particular volume presents several timely articles on the scanning transmission electron microscope. Updated with contributions from leading international scholars and industry experts Discusses hot topic areas and presents current and future research trends Provides an invaluable reference and guide for physicists, engineers and mathematicians.

Attractive electron correlation in wide band gap semiconductors by electron-photon interaction

International Nuclear Information System (INIS)

Takeda, Hiroyuki; Yoshino, Katsumi

2004-01-01

We theoretically demonstrate attractive electron correlation in wide band gap semiconductors by electron-photon interaction. At low temperature, wavevectors of electromagnetic waves absorbed in wide band gap semiconductors cannot be neglected for wavevectors of electron waves; that is, electromagnetic waves affect the movements of electrons. In particular, attractive interaction occurs between two electrons when one electron changes from a valence band to a conduction band and the other electron changes from a conduction band to a valence band

Electronic Publishing or Electronic Information Handling?

Science.gov (United States)

Heck, A.

The current dramatic evolution in information technology is bringing major modifications in the way scientists communicate. The concept of 'electronic publishing' is too restrictive and has often different, sometimes conflicting, interpretations. It is thus giving way to the broader notion of 'electronic information handling' encompassing the diverse types of information, the different media, as well as the various communication methodologies and technologies. New problems and challenges result also from this new information culture, especially on legal, ethical, and educational grounds. The procedures for validating 'published material' and for evaluating scientific activities will have to be adjusted too. 'Fluid' information is becoming a common concept. Electronic publishing cannot be conceived without link to knowledge bases nor without intelligent information retrieval tools.

Theoretical study of the interplay of electron-electron interaction and disorder

International Nuclear Information System (INIS)

Brezini, A.; Behilil, S.

1988-10-01

A disordered Hubbard model with diagonal disorder is used to investigate the electron localization effects associated with both disorder and electron-electron interaction. Extensive results are reported on the ground state properties and compared to other theories. Two regimes have been found: when the electron-electron interaction u is greater than the disorder parameter w and when u < w. (author). 18 refs, 4 figs

Defining Electron Bifurcation in the Electron-Transferring Flavoprotein Family.

Science.gov (United States)

Garcia Costas, Amaya M; Poudel, Saroj; Miller, Anne-Frances; Schut, Gerrit J; Ledbetter, Rhesa N; Fixen, Kathryn R; Seefeldt, Lance C; Adams, Michael W W; Harwood, Caroline S; Boyd, Eric S; Peters, John W

2017-11-01

Electron bifurcation is the coupling of exergonic and endergonic redox reactions to simultaneously generate (or utilize) low- and high-potential electrons. It is the third recognized form of energy conservation in biology and was recently described for select electron-transferring flavoproteins (Etfs). Etfs are flavin-containing heterodimers best known for donating electrons derived from fatty acid and amino acid oxidation to an electron transfer respiratory chain via Etf-quinone oxidoreductase. Canonical examples contain a flavin adenine dinucleotide (FAD) that is involved in electron transfer, as well as a non-redox-active AMP. However, Etfs demonstrated to bifurcate electrons contain a second FAD in place of the AMP. To expand our understanding of the functional variety and metabolic significance of Etfs and to identify amino acid sequence motifs that potentially enable electron bifurcation, we compiled 1,314 Etf protein sequences from genome sequence databases and subjected them to informatic and structural analyses. Etfs were identified in diverse archaea and bacteria, and they clustered into five distinct well-supported groups, based on their amino acid sequences. Gene neighborhood analyses indicated that these Etf group designations largely correspond to putative differences in functionality. Etfs with the demonstrated ability to bifurcate were found to form one group, suggesting that distinct conserved amino acid sequence motifs enable this capability. Indeed, structural modeling and sequence alignments revealed that identifying residues occur in the NADH- and FAD-binding regions of bifurcating Etfs. Collectively, a new classification scheme for Etf proteins that delineates putative bifurcating versus nonbifurcating members is presented and suggests that Etf-mediated bifurcation is associated with surprisingly diverse enzymes. IMPORTANCE Electron bifurcation has recently been recognized as an electron transfer mechanism used by microorganisms to maximize

Effects of electron-electron interactions on the electron distribution function of a plasma in the presence of an external electric field

International Nuclear Information System (INIS)

Molinari, V.G.; Pizzio, F.; Spiga, G.

1979-01-01

The electron distribution function, the electron temperature and some transport parameters (electrical conductivity and energy flow coefficient) are obtained starting from the nonlinear Boltzmann equation for a plasma under the action of an external electric field. The Fokker-Planck approximation is used for electron-electron and electron-ion interactions. The effects of electron-electron collisions are studied for different values of collision frequencies and electric field. (author)

Electron-excited molecule interactions

International Nuclear Information System (INIS)

Christophorou, L.G.; Tennessee Univ., Knoxville, TN

1991-01-01

In this paper the limited but significant knowledge to date on electron scattering from vibrationally/rotationally excited molecules and electron scattering from and electron impact ionization of electronically excited molecules is briefly summarized and discussed. The profound effects of the internal energy content of a molecule on its electron attachment properties are highlighted focusing in particular on electron attachment to vibrationally/rotationally and to electronically excited molecules. The limited knowledge to date on electron-excited molecule interactions clearly shows that the cross sections for certain electron-molecule collision processes can be very different from those involving ground state molecules. For example, optically enhanced electron attachment studies have shown that electron attachment to electronically excited molecules can occur with cross sections 10 6 to 10 7 times larger compared to ground state molecules. The study of electron-excited molecule interactions offers many experimental and theoretical challenges and opportunities and is both of fundamental and technological significance. 54 refs., 15 figs

Seeing with electrons

International Nuclear Information System (INIS)

Nellist, P.

2006-01-01

Commercially available lens correctors are extending the reach of electron microscopes to unprecedented atomic scales, as Peter Nellist describes. The electron microscope was invented in 1933 and is based on the principle that electrons have a wavelength that is inversely proportional to their momentum. There are two basic types: transmission electron microscopes and scanning electron microscopes, plus a hybrid of the two. The lenses in an electron microscope are provided by electromagnetic fields, but they suffer from spherical aberration. The addition of octupole and quadrupole corrector fields has improved the resolution of the electron microscope to better than 0.1 nm in the last decade. The next step is to correct for chromatic aberration, after which the resolution of the microscope will probably be limited by the size of the atom itself. (U.K.)

Introduction to electronics

CERN Multimedia

CERN. Geneva

2005-01-01

Electronics in HEP experiments: specificities and evolution The Art of Electronics: is there something beyond Ohm's law? Basic building blocks of Analog electronics: quickly understanding a schematic Charge preamps, current preamps and future preamps, shaping and the rest Electronics noise: fundamental and practical Evolution of technology: ASICs, FPGAs...

Multiple electron generation in a sea of electronic states

Science.gov (United States)

Witzel, Wayne; Shabaev, Andrew; Efros, Alexander; Hellberg, Carl; Verne, Jacobs

2009-03-01

In traditional bulk semiconductor photovoltaics (PVs), each photon may excite a single electron-hole, wasting excess energy beyond the band-gap as heat. In nanocrystals, multiple excitons can be generated from a single photon, enhancing the PV current. Multiple electron generation (MEG) may result from Coulombic interactions of the confined electrons. Previous investigations have been based on incomplete or over-simplified electronic-state representations. We present results of quantum simulations that include hundreds of thousands of configuration states and show how the complex dynamics, even in a closed electronic system, yields a saturated MEG effect on a femtosecond timescale. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Electron collision cross sections and electron swarm parameters for gas molecules

International Nuclear Information System (INIS)

Hayashi, Makoto

1986-01-01

Elastic and inelastic electron collision cross sections for molecules which interest in radiation research have been determined from available electron beam and electron swarm data by utilizing the Boltzmann equation and Monte Carlo simulation method. Electron drift velocity data which interest in radiation Pysics have been discussed and some calculated results of electron drift velocity data for CF 4 and CF 4 -inert gases mixtures will be presented. (author)

Low-altitude outbreaks of human fascioliasis related with summer rainfall in Gilan province, Iran

OpenAIRE

Abdoreza Salahi-Moghaddam; Majid Habibi-Nokhandam; Màrius V. Fuentes

2011-01-01

Following human fascioliasis outbreaks in 1988 and 1999 in Gilan province, northern Iran, efforts are now made to shed light on the seasonal pattern of fascioliasis transmission in this endemic area, taking into account snail host populations, climatic conditions and human cases. Populations of the intermediate host snail (Lymnaea spp.) peak in May and November, while there is a fourfold increase in the rate of human fascioliasis in February compared to that of September. Transmission is like...

Electronic payment systems

OpenAIRE

Mláka, Michal

2010-01-01

This bachelor thesis analysis issue of electronic payment systems. It discusses their use for payments on the internet and sending funds via e-mail. The first part is devoted to the theoretical definition and legislation of the issuance of electronic money and activities of electronic money institutions. The main part of the work clearly focuses on the use of e-wallets, which is an integral part of electronic payment systems. E-wallet of electronic payment system Moneybookers is considered as...

Wigner-like crystallization of Anderson-localized electron systems with low electron densities

CERN Document Server

Slutskin, A A; Pepper, M

2002-01-01

We consider an electron system under conditions of strong Anderson localization, taking into account interelectron long-range Coulomb repulsion. We establish that at sufficiently low electron densities and sufficiently low temperatures the Coulomb electron interaction brings about ordering of the Anderson-localized electrons into a structure that is close to an ideal (Wigner) crystal lattice, provided the dimension of the system is > 1. This Anderson-Wigner glass (AWG) is a new macroscopic electron state that, on the one hand, is beyond the conventional Fermi glass concept, and on the other hand, qualitatively differs from the known 'plain' Wigner glass (inherent in self-localized electron systems) in that the random slight electron displacements from the ideal crystal sites essentially depend on the electron density. With increasing electron density the AWG is found to turn into the plain Wigner glass or Fermi glass, depending on the width of the random spread of the electron levels. It is shown that the res...

Excess electrons in methanol clusters: Beyond the one-electron picture

Science.gov (United States)

Pohl, Gábor; Mones, Letif; Turi, László

2016-10-01

We performed a series of comparative quantum chemical calculations on various size negatively charged methanol clusters, ("separators=" CH 3 OH ) n - . The clusters are examined in their optimized geometries (n = 2-4), and in geometries taken from mixed quantum-classical molecular dynamics simulations at finite temperature (n = 2-128). These latter structures model potential electron binding sites in methanol clusters and in bulk methanol. In particular, we compute the vertical detachment energy (VDE) of an excess electron from increasing size methanol cluster anions using quantum chemical computations at various levels of theory including a one-electron pseudopotential model, several density functional theory (DFT) based methods, MP2 and coupled-cluster CCSD(T) calculations. The results suggest that at least four methanol molecules are needed to bind an excess electron on a hydrogen bonded methanol chain in a dipole bound state. Larger methanol clusters are able to form stronger interactions with an excess electron. The two simulated excess electron binding motifs in methanol clusters, interior and surface states, correlate well with distinct, experimentally found VDE tendencies with size. Interior states in a solvent cavity are stabilized significantly stronger than electron states on cluster surfaces. Although we find that all the examined quantum chemistry methods more or less overestimate the strength of the experimental excess electron stabilization, MP2, LC-BLYP, and BHandHLYP methods with diffuse basis sets provide a significantly better estimate of the VDE than traditional DFT methods (BLYP, B3LYP, X3LYP, PBE0). A comparison to the better performing many electron methods indicates that the examined one-electron pseudopotential can be reasonably used in simulations for systems of larger size.

Electron dose rate and photon contamination in electron arc therapy

International Nuclear Information System (INIS)

Pla, M.; Podgorsak, E.B.; Pla, C.

1989-01-01

The electron dose rate at the depth of dose maximum dmax and the photon contamination are discussed as a function of several parameters of the rotational electron beam. A pseudoarc technique with an angular increment of 10 degrees and a constant number of monitor units per each stationary electron field was used in our experiments. The electron dose rate is defined as the electron dose at a given point in phantom divided by the number of monitor units given for any one stationary electron beam. For a given depth of isocenter di the electron dose rates at dmax are linearly dependent on the nominal field width w, while for a given w the dose rates are inversely proportional to di. The dose rates for rotational electron beams with different di are related through the inverse square law provided that the two beams have (di,w) combinations which give the same characteristic angle beta. The photon dose at the isocenter depends on the arc angle alpha, field width w, and isocenter depth di. For constant w and di the photon dose at isocenter is proportional to alpha, for constant alpha and w it is proportional to di, and for constant alpha and di it is inversely proportional to w. The w and di dependence implies that for the same alpha the photon dose at the isocenter is inversely proportional to the electron dose rate at dmax

Power Electronics

DEFF Research Database (Denmark)

Iov, Florin; Ciobotaru, Mihai; Blaabjerg, Frede

2008-01-01

is to change the electrical power production sources from the conventional, fossil (and short term) based energy sources to renewable energy resources. The other is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss the most...... emerging renewable energy sources, wind energy, which by means of power electronics are changing from being a minor energy source to be acting as an important power source in the energy system. Power electronics is the enabling technology and the presentation will cover the development in wind turbine...... technology from kW to MW, discuss which power electronic solutions are most feasible and used today....

Electron Emission from Ultra-Large Area MOS Electron Emitters

DEFF Research Database (Denmark)

Thomsen, Lasse Bjørchmar; Nielsen, Gunver; Vendelbo, Søren Bastholm

2009-01-01

Ultralarge metal-oxide-semiconductor (MOS) devices with an active oxide area of 1 cm2 have been fabricated for use as electron emitters. The MOS structures consist of a Si substrate, a SiO2 tunnel barrier (~5 nm), a Ti wetting layer (3–10 Å), and a Au top layer (5–60 nm). Electron emission from...... layer is varied from 3 to 10 Å which changes the emission efficiency by more than one order of magnitude. The apparent mean free path of ~5 eV electrons in Au is found to be 52 Å. Deposition of Cs on the Au film increased the electron emission efficiency to 4.3% at 4 V by lowering the work function....... Electron emission under high pressures (up to 2 bars) of Ar was observed. ©2009 American Vacuum Society...

Comparative analysis of the terms "electronic commerce" and "electronic business"

OpenAIRE

Kavaliauskienė, Virginija; Šarapovas, Tadas

2002-01-01

Establishing the terms that clearly and consistently describe growing and dynamic networked economy is a critical first step toward further analysis and evaluation of electronic commerce and electronic business processes. Electronic commerce is making an impact on the ways that purchasing activities are being conducted. Much of the early literature on this subject was very speculative. However, the growth of e-commerce has enabled more observations to be made of the use of electronic business...

Electron-electron interaction and transfer ionization in fast ion-atom collisions

International Nuclear Information System (INIS)

Voitkiv, A B

2008-01-01

Recently it was pointed out that electron capture occurring in fast ion-atom collisions can proceed via a mechanism which earlier was not considered. In the present paper we study this mechanism in more detail. Similarly as in radiative capture, where the electron transfer occurs due to the interaction with the radiation field and proceeds via emission of a photon, within this mechanism the electron capture is caused by the interaction with another atomic electron leading mainly to the emission of the latter. In contrast to the electron-electron Thomas capture, this electron-electron (E-E) mechanism is basically a first-order one having similarities to the kinematic and radiative capture channels. It also possesses important differences with the latter two. Leading to transfer ionization, this first-order capture mechanism results in the electron emission mainly in the direction opposite to the motion of the projectile ion. The same, although less pronounced, feature is also characteristic for the momenta of the target recoil ions produced via this mechanism. It is also shown that the action of the E-E mechanism is clearly seen in recent experimental data on the transfer ionization in fast proton-helium collisions.

Determination of electron temperature and electron density in ...

African Journals Online (AJOL)

It is seen that the electron temperature increases from 5.8 × 102 oK to 7.83 × 104 oK as the pd is reduced from 130mm Hg × mm to 60 mm Hg × mm for argon. The electron densities increases from 2.8 × 1011/cm3 to 3.2 × 1011 /cm3 for the same variation of pds. For air the electron temperature increases from 3.6 × 104 oK to ...

Optimising electron microscopy experiment through electron optics simulation

Energy Technology Data Exchange (ETDEWEB)

Kubo, Y. [CEMES-CNRS, 29 Rue Jeanne Marvig, 31055 Toulouse France (France); Hitachi High-Technologies Corporation, 882, Ichige, Hitachinaka, Ibaraki 312-8504 (Japan); Gatel, C.; Snoeck, E. [CEMES-CNRS, 29 Rue Jeanne Marvig, 31055 Toulouse France (France); Houdellier, F., E-mail: florent.houdellier@cemes.fr [CEMES-CNRS, 29 Rue Jeanne Marvig, 31055 Toulouse France (France)

2017-04-15

We developed a new type of electron trajectories simulation inside a complete model of a modern transmission electron microscope (TEM). Our model incorporates the precise and real design of each element constituting a TEM, i.e. the field emission (FE) cathode, the extraction optic and acceleration stages of a 300 kV cold field emission gun, the illumination lenses, the objective lens, the intermediate and projection lenses. Full trajectories can be computed using magnetically saturated or non-saturated round lenses, magnetic deflectors and even non-cylindrical symmetry elements like electrostatic biprism. This multi-scale model gathers nanometer size components (FE tip) with parts of meter length (illumination and projection systems). We demonstrate that non-trivial TEM experiments requiring specific and complex optical configurations can be simulated and optimized prior to any experiment using such model. We show that all the currents set in all optical elements of the simulated column can be implemented in the real column (I2TEM in CEMES) and used as starting alignment for the requested experiment. We argue that the combination of such complete electron trajectory simulations in the whole TEM column with automatic optimization of the microscope parameters for optimal experimental data (images, diffraction, spectra) allows drastically simplifying the implementation of complex experiments in TEM and will facilitate the development of advanced use of the electron microscope in the near future. - Highlights: • Using dedicated electron optics software, we calculate full electrons trajectories inside a modern transmission electron microscope. • We have determined how to deal with multi-scale electron optics elements like high voltage cold field emission source. • W • e have succeed to model both weak and strong magnetic lenses whether in saturated or unsaturated conditions as well as electrostatic biprism and magnetic deflectors. • We have applied this model

Optimising electron microscopy experiment through electron optics simulation

International Nuclear Information System (INIS)

Kubo, Y.; Gatel, C.; Snoeck, E.; Houdellier, F.

2017-01-01

We developed a new type of electron trajectories simulation inside a complete model of a modern transmission electron microscope (TEM). Our model incorporates the precise and real design of each element constituting a TEM, i.e. the field emission (FE) cathode, the extraction optic and acceleration stages of a 300 kV cold field emission gun, the illumination lenses, the objective lens, the intermediate and projection lenses. Full trajectories can be computed using magnetically saturated or non-saturated round lenses, magnetic deflectors and even non-cylindrical symmetry elements like electrostatic biprism. This multi-scale model gathers nanometer size components (FE tip) with parts of meter length (illumination and projection systems). We demonstrate that non-trivial TEM experiments requiring specific and complex optical configurations can be simulated and optimized prior to any experiment using such model. We show that all the currents set in all optical elements of the simulated column can be implemented in the real column (I2TEM in CEMES) and used as starting alignment for the requested experiment. We argue that the combination of such complete electron trajectory simulations in the whole TEM column with automatic optimization of the microscope parameters for optimal experimental data (images, diffraction, spectra) allows drastically simplifying the implementation of complex experiments in TEM and will facilitate the development of advanced use of the electron microscope in the near future. - Highlights: • Using dedicated electron optics software, we calculate full electrons trajectories inside a modern transmission electron microscope. • We have determined how to deal with multi-scale electron optics elements like high voltage cold field emission source. • W • e have succeed to model both weak and strong magnetic lenses whether in saturated or unsaturated conditions as well as electrostatic biprism and magnetic deflectors. • We have applied this model

Lead-Free Electronics: Impact for Space Electronics

Science.gov (United States)

Sampson, Michael J.

2010-01-01

Pb is used as a constituent in solder alloys used to connect and attach electronic parts to printed wiring boards (PWBs). Similar Pbbearing alloys are electroplated or hot dipped onto the terminations of electronic parts to protect the terminations and make them solderable. Changing to Pb-free solders and termination finishes has introduced significant technical challenges into the supply chain. Tin/lead (Sn/Pb) alloys have been the solders of choice for electronics for more than 50 years. Pb-free solder alloys are available but there is not a plug-in replacement for 60/40 or 63/37 (Sn/Pb) alloys, which have been the industry workhorses.

Observation of electron plasma waves in plasma of two-temperature electrons

International Nuclear Information System (INIS)

Ikezawa, Shunjiro; Nakamura, Yoshiharu.

1981-01-01

Propagation of electron plasma waves in a large and unmagnetized plasma containing two Maxwellian distributions of electrons is studied experimentally. Two kinds of plasma sources which supply electrons of different temperature are used. The temperature ratio is about 3 and the density ratio of hot to cool electrons is varied from 0 to 0.5. A small contamination of hot electrons enhances the Landau damping of the principal mode known as the Bohm-Gross mode. When the density of hot electrons is larger than about 0.2, two modes are observed. The results agree with theoretical dispersion relations when excitation efficiencies of the modes are considered. (author)

Electron energy and electron trajectories in an inverse free-electron laser accelerator based on a novel electrostatic wiggler

Science.gov (United States)

Nikrah, M.; Jafari, S.

2016-06-01

We expand here a theory of a high-gradient laser-excited electron accelerator based on an inverse free-electron laser (inverse-FEL), but with innovations in the structure and design. The electrostatic wiggler used in our scheme, namely termed the Paul wiggler, is generated by segmented cylindrical electrodes with applied oscillatory voltages {{V}\\text{osc}}(t) over {{90}\\circ} segments. The inverse-FEL interaction can be described by the equations that govern the electron motion in the combined fields of both the laser pulse and Paul wiggler field. A numerical study of electron energy and electron trajectories has been made using the fourth-order Runge-Kutta method. The results indicate that the electron attains a considerable energy at short distances in this device. It is found that if the electron has got sufficient suitable wiggler amplitude intensities, it can not only gain higher energy in longer distances, but also can retain it even after the passing of the laser pulse. In addition, the results reveal that the electron energy gains different peaks for different initial axial velocities, so that a suitable small initial axial velocity of e-beam produces substantially high energy gain. With regard to the transverse confinement of the electron beam in a Paul wiggler, there is no applied axial guide magnetic field in this device.

Plasmaspheric electron content

International Nuclear Information System (INIS)

Hartmann, G.K.

1978-01-01

Measurements of the plasmaspheric electron content are reviewed with particular reference to the ATS-6 radio beacon experiment. From the review, it appears likely that measurement of the plasmaspheric electron content is the only one capable of monitoring electron fluxes continuously between L 1 and L 2. Some recent important results deduced from plasmaspheric electron content measurements are discussed

A 20 keV electron gun system for the electron irradiation experiments

International Nuclear Information System (INIS)

Mahapatra, S.K.; Dhole, S.D.; Bhoraskar, V.N.

2005-01-01

An electron gun consisting of cathode, focusing electrode, control electrode and anode has been designed and fabricated for the electron irradiation experiments. This electron gun can provide electrons of any energy over the range 1-20 keV, with current upto 50 μA. This electron gun and a Faraday cup are mounted in the cylindrical chamber. The samples are fixed on the Faraday cup and irradiated with electrons at a pressure ∼10 -7 mbar. The special features of this electron gun system are that, at any electron energy above 1 keV, the electron beam diameter can be varied from 5 to 120 mm on the Faraday cup mounted at a distance of 200 mm from the anode in the chamber. The variation in the electron current over the beam spot of 120 mm diameter is less than 15% and the beam current stability is better than 5%. This system is being used for studying the irradiation effects of 1-20 keV energy electrons on the space quality materials in which the irradiation time may vary from a few tens of seconds to hours

A 20 keV electron gun system for the electron irradiation experiments

Energy Technology Data Exchange (ETDEWEB)

Mahapatra, S.K. [Department of Physics, University of Pune, Pune 411007 (India); Dhole, S.D. [Department of Physics, University of Pune, Pune 411007 (India); Bhoraskar, V.N. [Department of Physics, University of Pune, Pune 411007 (India)]. E-mail: vnb@physics.unipune.ernet.in

2005-01-01

An electron gun consisting of cathode, focusing electrode, control electrode and anode has been designed and fabricated for the electron irradiation experiments. This electron gun can provide electrons of any energy over the range 1-20 keV, with current upto 50 {mu}A. This electron gun and a Faraday cup are mounted in the cylindrical chamber. The samples are fixed on the Faraday cup and irradiated with electrons at a pressure {approx}10{sup -7} mbar. The special features of this electron gun system are that, at any electron energy above 1 keV, the electron beam diameter can be varied from 5 to 120 mm on the Faraday cup mounted at a distance of 200 mm from the anode in the chamber. The variation in the electron current over the beam spot of 120 mm diameter is less than 15% and the beam current stability is better than 5%. This system is being used for studying the irradiation effects of 1-20 keV energy electrons on the space quality materials in which the irradiation time may vary from a few tens of seconds to hours.

Effect of electron beam on the properties of electron-acoustic rogue waves

Science.gov (United States)

El-Shewy, E. K.; Elwakil, S. A.; El-Hanbaly, A. M.; Kassem, A. I.

2015-04-01

The properties of nonlinear electron-acoustic rogue waves have been investigated in an unmagnetized collisionless four-component plasma system consisting of a cold electron fluid, Maxwellian hot electrons, an electron beam and stationary ions. It is found that the basic set of fluid equations is reduced to a nonlinear Schrodinger equation. The dependence of rogue wave profiles and the associated electric field on the carrier wave number, normalized density of hot electron and electron beam, relative cold electron temperature and relative beam temperature are discussed. The results of the present investigation may be applicable in auroral zone plasma.

Electron cooling and recombination experiments with an adiabatically expanded electron beam

International Nuclear Information System (INIS)

Pastuszka, S.; Heidelberg Univ.; Schramm, U.; Heidelberg Univ.; Grieser, M.; Heidelberg Univ.; Broude, C.; Heidelberg Univ.; Grimm, R.; Heidelberg Univ.; Habs, D.; Heidelberg Univ.; Kenntner, J.; Heidelberg Univ.; Miesner, H.J.; Heidelberg Univ.; Schuessler, T.; Heidelberg Univ.; Schwalm, D.; Heidelberg Univ.; Wolf, A.; Heidelberg Univ.

1996-01-01

Magnetically guided electron beams with transverse temperatures reduced with respect to the cathode temperature by a factor of more than 7 were realized in the electron cooling device of the heavy-ion storage ring TSR and the effect of the reduced transverse temperature in recombination and electron cooling experiments was studied. Measured dielectronic recombination resonances at low relative energy and spectra of laser-stimulated recombination indicate that transverse electron temperatures of about 17 meV have been obtained at cathode temperatures of about 110 meV. The temperature dependence of the spontaneous electron-ion recombination rate during electron cooling was investigated and found to follow the inverse square-root law expected from the theory of radiative recombination, although the measured absolute rates are higher than predicted. A new method based on analyzing the intensity of the fluorescence light emitted during simultaneous laser and electron cooling is used to measure the longitudinal electron cooling force in a range of relative velocities extending over two orders of magnitude (10 5 -10 7 cm/s). The results confirm the occurrence of 'magnetized electron cooling' also at the reduced transverse temperature and show that, compared to earlier measurements at the high transverse temperature, the cooling force increases by about a factor of 2; a considerably larger increase by a factor of ∼5 would be expected if 'magnetized electron cooling' would not exist. (orig.)

Electronic structure of elements and compounds and electronic phases of solids

International Nuclear Information System (INIS)

Nadykto, B.A.

2000-01-01

The paper reviews technique and computed energies for various electronic states of many-electron multiply charged ions, molecular ions, and electronic phases of solids. The model used allows computation of the state energy for free many-electron multiply charged ions with relative accuracy ∼10 -4 suitable for analysis of spectroscopy data

Three-dimensional nanofabrication by electron-beam-induced deposition using 200-keV electrons in scanning transmission electron microscope

International Nuclear Information System (INIS)

Liu, Z.Q.; Mitsuishi, K.; Furuya, K.

2005-01-01

Attempts were made to fabricate three-dimensional nanostructures on and out of a substrate by electron-beam-induced deposition in a 200-kV scanning transmission electron microscope. Structures with parallel wires over the substrate surface were difficult to fabricate due to the direct deposition of wires on both top and bottom surfaces of the substrate. Within the penetration depth of the incident electron beam, nanotweezers were fabricated by moving the electron beam beyond different substrate layers. Combining the deposition of self-supporting wires and self-standing tips, complicated three-dimensional doll-like, flag-like, and gate-like nanostructures that extend out of the substrate were successfully fabricated with one-step or multi-step scans of the electron beam. Effects of coarsening, nucleation, and distortion during electron-beam-induced deposition are discussed. (orig.)

Secondary electron emission yield in the limit of low electron energy

CERN Document Server

Andronov, A.N.; Kaganovich, I.D.; Startsev, E.A.; Raitses, Y.; Demidov, V.I.

2013-04-22

Secondary electron emission (SEE) from solids plays an important role in many areas of science and technology.1 In recent years, there has been renewed interest in the experimental and theoretical studies of SEE. A recent study proposed that the reflectivity of very low energy electrons from solid surface approaches unity in the limit of zero electron energy2,3,4, If this was indeed the case, this effect would have profound implications on the formation of electron clouds in particle accelerators,2-4 plasma measurements with electrostatic Langmuir probes, and operation of Hall plasma thrusters for spacecraft propulsion5,6. It appears that, the proposed high electron reflectivity at low electron energies contradicts to numerous previous experimental studies of the secondary electron emission7. The goal of this note is to discuss possible causes of these contradictions.

Electron spectroscopy

International Nuclear Information System (INIS)

Hegde, M.S.

1979-01-01

An introduction to the various techniques in electron spectroscopy is presented. These techniques include: (1) UV Photoelectron spectroscopy, (2) X-ray Photoelectron spectroscopy, (3) Auger electron spectroscopy, (4) Electron energy loss spectroscopy, (5) Penning ionization spectroscopy and (6) Ion neutralization spectroscopy. The radiations used in each technique, the basis of the technique and the special information obtained in structure determination in atoms and molecules by each technique are summarised. (A.K.)

Perpendicular electron cyclotron emission from hot electrons in TMX-U

International Nuclear Information System (INIS)

James, R.A.; Ellis, R.F.; Lasnier, C.J.; Casper, T.A.; Celata, C.M.

1984-01-01

Perpendicular electron cyclotron emission (PECE) from the electron cyclotron resonant heating of hot electrons in TMX-U is measured at 30 to 40 and 50 to 75 GHz. This emission is optically thin and is measured at the midplane, f/sub ce/ approx. = 14 GHz, in either end cell. In the west end cell, the emission can be measured at different axial positions thus yielding the temporal history of the hot electron axial profile. These profiles are in excellent agreement with the axial diamagnetic signals. In addition, the PECE signal level correlates well with the diamagnetic signal over a wide range of hot electron densities. Preliminary results from theoretical modeling and comparisons with other diagnostics are also presented

A ferroelectric electron gun in a free-electron maser experiment

International Nuclear Information System (INIS)

Einat, M.; Jerby, E.; Rosenman, G.

2002-01-01

An electron-gun based on a ferroelectric cathode is studied in a free-electron maser (FEM) experiment. In this gun, the electrons are separated from the cathode surface plasma, and are accelerated in two stages. The electron energy-spread is reduced sufficiently for an FEM operation in the microwave regime. A 14 keV, 1-2 A e-beam is obtained in a 0.1-2.1 μs pulse width. The pulse repetition frequency attains 3.1 MHz in ∼50% duty-cycle. This gun is implemented in an FEM oscillator experiment operating around 3 GHz. The paper presents experimental results and discusses the applicability of ferroelectric guns in free-electron laser devices

A ferroelectric electron gun in a free-electron maser experiment

CERN Document Server

Einat, M; Rosenman, G

2002-01-01

An electron-gun based on a ferroelectric cathode is studied in a free-electron maser (FEM) experiment. In this gun, the electrons are separated from the cathode surface plasma, and are accelerated in two stages. The electron energy-spread is reduced sufficiently for an FEM operation in the microwave regime. A 14 keV, 1-2 A e-beam is obtained in a 0.1-2.1 mu s pulse width. The pulse repetition frequency attains 3.1 MHz in approx 50% duty-cycle. This gun is implemented in an FEM oscillator experiment operating around 3 GHz. The paper presents experimental results and discusses the applicability of ferroelectric guns in free-electron laser devices.

Paper electronics.

Science.gov (United States)

Tobjörk, Daniel; Österbacka, Ronald

2011-05-03

Paper is ubiquitous in everyday life and a truly low-cost substrate. The use of paper substrates could be extended even further, if electronic applications would be applied next to or below the printed graphics. However, applying electronics on paper is challenging. The paper surface is not only very rough compared to plastics, but is also porous. While this is detrimental for most electronic devices manufactured directly onto paper substrates, there are also approaches that are compatible with the rough and absorptive paper surface. In this review, recent advances and possibilities of these approaches are evaluated and the limitations of paper electronics are discussed. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Destabilization of the electron Bernstein modes by runaway electrons

International Nuclear Information System (INIS)

Hitchcock, D.A.; Mahajan, S.M.

1982-01-01

It is shown that the electromagnetic finite k/sub parallel/ electron Bernstein mode can be destabilized by the runaway electron distribution which results from the quasilinear action of the magnetized plasma oscillation. This mechanism is shown to yield growth rates of the order of 10 8 sec -1 and is suggested as a mechanism for the enchanced cyclotron harmonic emission in the presence of runaway electrons

Surface-electronic-state effects in electron emission from the Be(0001) surface

International Nuclear Information System (INIS)

Archubi, C. D.; Gravielle, M. S.; Silkin, V. M.

2011-01-01

We study the electron emission produced by swift protons impinging grazingly on a Be(0001) surface. The process is described within a collisional formalism using the band-structure-based (BSB) approximation to represent the electron-surface interaction. The BSB model provides an accurate description of the electronic band structure of the solid and the surface-induced potential. Within this approach we derive both bulk and surface electronic states, with these latter characterized by a strong localization at the crystal surface. We found that such surface electronic states play an important role in double-differential energy- and angle-resolved electron emission probabilities, producing noticeable structures in the electron emission spectra.

Surface-electronic-state effects in electron emission from the Be(0001) surface

Energy Technology Data Exchange (ETDEWEB)

Archubi, C. D. [Instituto de Astronomia y Fisica del Espacio, casilla de correo 67, sucursal 28, C1428EGA, Buenos Aires (Argentina); Gravielle, M. S. [Instituto de Astronomia y Fisica del Espacio, casilla de correo 67, sucursal 28, C1428EGA, Buenos Aires (Argentina); Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires (Argentina); Silkin, V. M. [Donostia International Physics Center, E-20018 San Sebastian (Spain); Departamento de Fisica de Materiales, Facultad de Ciencias Quimicas, Universidad del Pais Vasco, Apartado 1072, E-20080 San Sebastian (Spain); IKERBASQUE, Basque Foundation for Science, E-48011 Bilbao (Spain)

2011-07-15

We study the electron emission produced by swift protons impinging grazingly on a Be(0001) surface. The process is described within a collisional formalism using the band-structure-based (BSB) approximation to represent the electron-surface interaction. The BSB model provides an accurate description of the electronic band structure of the solid and the surface-induced potential. Within this approach we derive both bulk and surface electronic states, with these latter characterized by a strong localization at the crystal surface. We found that such surface electronic states play an important role in double-differential energy- and angle-resolved electron emission probabilities, producing noticeable structures in the electron emission spectra.

Simulation of the electron acoustic instability for a finite-size electron beam system

International Nuclear Information System (INIS)

Lin, C.S.; Winske, D.

1987-01-01

Satellite observations at midlatitudes (≅20,000 km) near the earth's dayside polar cusp boundary layer indicate that the upward electron beams have a narrow latitudinal width up to 0.1 0 . In the cusp boundary layer where the electron population consists of a finite-size electron beam in a background of uniform cold and hot electrons, the electron acoustic mode is unstable inside the electron beam but damped outside the electron beam. Simulations of the electron acoustic instability for a finite-size beam system are carried out with a particle-in-cell code to investigate the heating phenomena associated with the instability and the width of the heating region. The simulations show that the finite-size electron beam radiates electrostatic electron acoustic waves. The decay length of the electron acoustic waves outside the beam in the simulation agrees with the spatial decay length derived from the linear dispersion equation

Arbitrary amplitude slow electron-acoustic solitons in three-electron temperature space plasmas

International Nuclear Information System (INIS)

Mbuli, L. N.; Maharaj, S. K.; Bharuthram, R.; Singh, S. V.; Lakhina, G. S.

2015-01-01

We examine the characteristics of large amplitude slow electron-acoustic solitons supported in a four-component unmagnetised plasma composed of cool, warm, hot electrons, and cool ions. The inertia and pressure for all the species in this plasma system are retained by assuming that they are adiabatic fluids. Our findings reveal that both positive and negative potential slow electron-acoustic solitons are supported in the four-component plasma system. The polarity switch of the slow electron-acoustic solitons is determined by the number densities of the cool and warm electrons. Negative potential solitons, which are limited by the cool and warm electron number densities becoming unreal and the occurrence of negative potential double layers, are found for low values of the cool electron density, while the positive potential solitons occurring for large values of the cool electron density are only limited by positive potential double layers. Both the lower and upper Mach numbers for the slow electron-acoustic solitons are computed and discussed

Electron cloud dynamics in the Cornell Electron Storage Ring Test Accelerator wiggler

Directory of Open Access Journals (Sweden)

C. M. Celata

2011-04-01

Full Text Available The interference of stray electrons (also called “electron clouds” with accelerator beams is important in modern intense-beam accelerators, especially those with beams of positive charge. In magnetic wigglers, used, for instance, for transverse emittance damping, the intense synchrotron radiation produced by the beam can generate an electron cloud of relatively high density. In this paper the complicated dynamics of electron clouds in wigglers is examined using the example of a wiggler in the Cornell Electron Storage Ring Test Accelerator experiment at the Cornell Electron Storage Ring. Three-dimensional particle-in-cell simulations with the WARP-POSINST computer code show different density and dynamics for the electron cloud at locations near the maxima of the vertical wiggler field when compared to locations near the minima. Dynamics in these regions, the electron cloud distribution vs longitudinal position, and the beam coherent tune shift caused by the wiggler electron cloud will be discussed.

Arbitrary amplitude fast electron-acoustic solitons in three-electron component space plasmas

Energy Technology Data Exchange (ETDEWEB)

Mbuli, L. N.; Maharaj, S. K. [South African National Space Agency (SANSA) Space Science, P.O. Box 32, Hermanus 7200, Republic of South Africa (South Africa); Department of Physics, University of the Western Cape (UWC), Robert Sobukwe Road, Bellville 7535, Republic of South Africa (South Africa); Bharuthram, R. [Department of Physics, University of the Western Cape (UWC), Robert Sobukwe Road, Bellville 7535, Republic of South Africa (South Africa); Singh, S. V.; Lakhina, G. S. [Indian Institute of Geomagnetism, New Panvel (West), Navi Mumbai 410218 (India); Department of Physics, University of the Western Cape (UWC), Robert Sobukwe Road, Bellville 7535, Republic of South Africa (South Africa)

2016-06-15

We examine the characteristics of fast electron-acoustic solitons in a four-component unmagnetised plasma model consisting of cool, warm, and hot electrons, and cool ions. We retain the inertia and pressure for all the plasma species by assuming adiabatic fluid behaviour for all the species. By using the Sagdeev pseudo-potential technique, the allowable Mach number ranges for fast electron-acoustic solitary waves are explored and discussed. It is found that the cool and warm electron number densities determine the polarity switch of the fast electron-acoustic solitons which are limited by either the occurrence of fast electron-acoustic double layers or warm and hot electron number density becoming unreal. For the first time in the study of solitons, we report on the coexistence of fast electron-acoustic solitons, in addition to the regular fast electron-acoustic solitons and double layers in our multi-species plasma model. Our results are applied to the generation of broadband electrostatic noise in the dayside auroral region.

Electronic Market and Business: Cyberspace vs. Electronic Environment

Directory of Open Access Journals (Sweden)

Deniss Ščeulovs

2013-12-01

Full Text Available The authors of the article analyze the concept "electronic environment". Having studied a range of academic literature sources and other sources, the authors of the article have drawn a conclusion that the academic writings do not provide a definition of "electronic environment". Furthermore, the various opinions among specialists regarding this concept often differ. Meanwhile, there are several explanations of the term "cyberspace" overlapping the concept of "electronic environment", and these terms are often believed to be synonyms. To understand what the term "electronic environment" means and to properly and correctly employ this concept in entrepreneurship, the authors have performed a lexicographic analysis of this concept by comparing reciprocal concepts. As a result of the research, the authors propose their view on what, in their opinion, "electronic environment" is and what its connection to the concept "cyberspace" is. The topicality of the article lies in the fact that often entrepreneurs and specialists of public and other institutions, when using these terms, imply completely different concepts. It can lead to misunderstanding and misinterpreting the information, as well as to encumbering the understanding of tasks, problems, etc.

Practical XHV electron gun

International Nuclear Information System (INIS)

Urata, Tomohiro; Ishikawa, Tsuyoshi; Cho, Boklae; Oshima, Chuhei

2008-01-01

We have developed practical XHV chambers of a electron gun, of which the operating pressures are 1x10 -9 Pa in a stainless-steel one and 4x10 -9 Pa in a permalloy one. By mounting a noble single-atom electron source with high brightness and high spatial coherence on the electron gun including electron optics, we demonstrated highly collimated electron-beam emission: ∼80% of the total emission current entered the electron optics. This ratio was two or three orders of magnitude higher than those of the conventional electron sources. In XHV, in addition, we confirmed stable electron emission up to 20 nA, which results in the specimen current high enough for scanning electron microscopes. (author)

Two-Electron Transfer Pathways.

Science.gov (United States)

Lin, Jiaxing; Balamurugan, D; Zhang, Peng; Skourtis, Spiros S; Beratan, David N

2015-06-18

The frontiers of electron-transfer chemistry demand that we develop theoretical frameworks to describe the delivery of multiple electrons, atoms, and ions in molecular systems. When electrons move over long distances through high barriers, where the probability for thermal population of oxidized or reduced bridge-localized states is very small, the electrons will tunnel from the donor (D) to acceptor (A), facilitated by bridge-mediated superexchange interactions. If the stable donor and acceptor redox states on D and A differ by two electrons, it is possible that the electrons will propagate coherently from D to A. While structure-function relations for single-electron superexchange in molecules are well established, strategies to manipulate the coherent flow of multiple electrons are largely unknown. In contrast to one-electron superexchange, two-electron superexchange involves both one- and two-electron virtual intermediate states, the number of virtual intermediates increases very rapidly with system size, and multiple classes of pathways interfere with one another. In the study described here, we developed simple superexchange models for two-electron transfer. We explored how the bridge structure and energetics influence multielectron superexchange, and we compared two-electron superexchange interactions to single-electron superexchange. Multielectron superexchange introduces interference between singly and doubly oxidized (or reduced) bridge virtual states, so that even simple linear donor-bridge-acceptor systems have pathway topologies that resemble those seen for one-electron superexchange through bridges with multiple parallel pathways. The simple model systems studied here exhibit a richness that is amenable to experimental exploration by manipulating the multiple pathways, pathway crosstalk, and changes in the number of donor and acceptor species. The features that emerge from these studies may assist in developing new strategies to deliver multiple

Electron-Electron and Electron-Phonon interactions effects on the tunnel electronic spectrum of PbS quantum dots

Science.gov (United States)

Wang, Hongyue; Lhuillier, Emmanuel; Yu, Qian; Mottaghizadeh, Alireza; Ulysse, Christian; Zimmers, Alexandre; Dubertret, Benoit; Aubin, Herve

2015-03-01

We present a tunnel spectroscopy study of the electronic spectrum of single PbS Quantum Dots (QDs) trapped between nanometer-spaced electrodes, measured at low temperature T=5 K. The carrier filling of the QD can be controlled either by the drain voltage in the shell filling regime or by a gate voltage. In the empty QD, the tunnel spectrum presents the expected signature of the 8x degenerated excited levels. In the drain controlled shell filling regime, the levels degeneracies are lifted by the global electrostatic Coulomb energy of the QD; in the gate controlled shell filling regime, the levels degeneracies are lifted by the intra-Coulomb interactions. In the charged quantum dot, electron-phonons interactions lead to the apparition of Franck-Condon side bands on the single excited levels and possibly Franck Condon blockade at low energy. The sharpening of excited levels at higher gate voltage suggests that the magnitude of electron-phonon interactions is decreased upon increasing the electron filling in the quantum dot. This work was supported by the French ANR Grants 10-BLAN-0409-01, 09-BLAN-0388-01, by the Region Ile-de-France in the framework of DIM Nano-K and by China Scholarship Council.

Electron emitting filaments for electron discharge devices

International Nuclear Information System (INIS)

Leung, K.N.; Pincosy, P.A.; Ehlers, K.W.

1988-01-01

This patent describes an electron emitting device for use in an electron discharge system. It comprises: a filament having a pair of terminal ends, electrical supply means for supplying electrical power to the terminal ends of the filament for directly heating the filament by the passage of an electrical current along the filament between the terminal ends, the filament being substantially tapered in cross section continuously in one direction from one of its pair of terminal ends to another of its pair of terminal ends to achieve uniform heating of the filament along the length thereof by compensating for the nonuniform current along the filament due to the emission of electrons therefrom

Electron irradiation-induced destruction of carbon nanotubes in electron microscopes

International Nuclear Information System (INIS)

Molhave, Kristian; Gudnason, Sven Bjarke; Pedersen, Anders Tegtmeier; Clausen, Casper Hyttel; Horsewell, Andy; Boggild, Peter

2007-01-01

Observations of carbon nanotubes under exposure to electron beam irradiation in standard transmission electron microscope (TEM) and scanning electron microscope (SEM) systems show that such treatment in some cases can cause severe damage of the nanotube structure, even at electron energies far below the approximate 100 keV threshold for knock-on damage displacing carbon atoms in the graphene structure. We find that the damage we observe in one TEM can be avoided by use of a cold finger. This and the morphology of the damage imply that water vapour, which is present as a background gas in many vacuum chambers, can damage the nanotube structure through electron beam-induced chemical reactions. Though, the dependence on the background gas makes these observations specific for the presently used systems, the results demonstrate the importance of careful assessment of the level of subtle structural damage that the individual electron microscope system can do to nanostructures during standard use

Electron-attachment processes

International Nuclear Information System (INIS)

Christophorou, L.G.; McCorkle, D.L.; Christodoulides, A.A.

1982-01-01

Topics covered include: (1) modes of production of negative ions, (2) techniques for the study of electron attachment processes, (3) dissociative electron attachment to ground-state molecules, (4) dissociative electron attachment to hot molecules (effects of temperature on dissociative electron attachment), (5) molecular parent negative ions, and (6) negative ions formed by ion-pair processes and by collisions of molecules with ground state and Rydberg atoms

Genetic diversity among natural populations of Ottelia acuminata ...

African Journals Online (AJOL)

PRECIOUS

2009-11-16

Nov 16, 2009 ... is essential for establishing effective and efficient conser- vation and breeding ... overlaid with 40 µl mineral oil. Amplifications were .... Diversity for Nineteen Populations of Pinus sibirica Du Tour with. Technique of ISSR.

Genetic diversity among natural populations of Ottelia acuminata ...

African Journals Online (AJOL)

PRECIOUS

2009-11-16

Nov 16, 2009 ... A total number of 120 O. acuminate accessions were analyzed, by amplification of their DNAs with 15 ... mortar and pestle. The powder was transferred to a 25 ml sterile. Falcon tube with 10 ml of CTAB buffer. The extraction buffer con- sisted of 2% (w/v) CTAB (cetyltrimethyl ammonium bromide,. Sigma), 1.5 ...

Acceleration of electrons using an inverse free electron laser auto- accelerator

International Nuclear Information System (INIS)

Wernick, I.K.; Marshall, T.C.

1992-07-01

We present data from our study of a device known as the inverse free electron laser. First, numerical simulations were performed to optimize the design parameters for an experiment that accelerates electrons in the presence of an undulator by stimulated absorption of radiation. The Columbia free electron laser (FEL) was configured as an auto-accelerator (IFELA) system; high power (MW's) FEL radiation at ∼1.65 mm is developed along the first section of an undulator inside a quasi-optical resonator. The electron beam then traverses a second section of undulator where a fraction of the electrons is accelerated by stimulated absorption of the 1.65 mm wavelength power developed in the first undulator section. The second undulator section has very low gain and does not generate power on its own. We have found that as much as 60% of the power generated in the first section can be absorbed in the second section, providing that the initial electron energy is chosen correctly with respect to the parameters chosen for the first and second undulators. An electron momentum spectrometer is used to monitor the distribution of electron energies as the electrons exit the IFELA. We have found; using our experimental parameters, that roughly 10% of the electrons are accelerated to energies as high as 1100 keV, in accordance with predictions from the numerical model. The appearance of high energy electrons is correlated with the abrupt absorption of millimeter power. The autoaccelerator configuration is used because there is no intense source of coherent power at the 1.65 mm design wavelength other than the FEL

Advanced Electronics

Science.gov (United States)

2017-07-21

AFRL-RV-PS- AFRL-RV-PS- TR-2017-0114 TR-2017-0114 ADVANCED ELECTRONICS Ashwani Sharma 21 Jul 2017 Interim Report APPROVED FOR PUBLIC RELEASE...NUMBER Advanced Electronics 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62601F 6. AUTHOR(S) 5d. PROJECT NUMBER 4846 Ashwani Sharma 5e. TASK NUMBER...Approved for public release; distribution is unlimited. (RDMX-17-14919 dtd 20 Mar 2018) 13. SUPPLEMENTARY NOTES 14. ABSTRACT The Space Electronics

The Downshift of Electron Plasma Oscillations in the Electron Foreshock Region.

Science.gov (United States)

1984-10-10

Ii D-Ai50 52 THE DOWNSHIFT OF ELECTRON PLASMA OSCILLATIONS IN THE i/1. ELECTRON FORESHOCK R.. (U) I0MM UNIV 10MM CITY DEPT OF PHYSICS AND ASTRONOMY 5...OSCILLATIONS 0 IN THE ELECTRON FORESHOCK REGION In by S. A. Fuselierl, D. A. Gurnett 1 , Ace NTI 0. and R. J. Fitzenreiter 2 DTI I ,3WERSflY o. 06UNDED ISAI...geleasel Ditibto Unlimited 02 1 16 U. of Iowa 84-21 THE DOWNSHIFT OF ELECTRON PLASMA OSCILLATIONSJ / IN THE ELECTRON FORESHOCK REGION t - by Z I S. A

Electronics engineer's reference book

CERN Document Server

Mazda, F F

1989-01-01

Electronics Engineer's Reference Book, Sixth Edition is a five-part book that begins with a synopsis of mathematical and electrical techniques used in the analysis of electronic systems. Part II covers physical phenomena, such as electricity, light, and radiation, often met with in electronic systems. Part III contains chapters on basic electronic components and materials, the building blocks of any electronic design. Part IV highlights electronic circuit design and instrumentation. The last part shows the application areas of electronics such as radar and computers.

Angular distribution of scattered electron and medium energy electron spectroscopy for metals

International Nuclear Information System (INIS)

Oguri, Takeo; Ishioka, Hisamichi; Fukuda, Hisashi; Irako, Mitsuhiro

1986-01-01

The angular distribution (AD) of scattered electrons produced by medium energy incident electrons (E P = 50 ∼ 300 eV) from polycrystalline Ti, Fe, Ni, Cu and Au were obtained by the angle-resolved medium energy electron spectrometer. The AD of the energy loss peaks are similar figures to AD of the elastically reflected electron peaks. Therefore, the exchanged electrons produced by the knock-on collision between the incident electrons and those of metals without momentum transfer are observed as the energy loss spectra (ELS). This interpretation differs from the inconsequent interpretation by the dielectric theory or the interband transition. The information depth and penetration length are obtained from AD of the Auger electron peaks. The contribution of the surface to spectra is 3 % at the maximum for E P = 50 eV. The true secondary peaks representing the secondary electron emission spectroscopy (SES) are caused by the emissions of the energetic electrons (kT e ≥ 4 eV), and SES is the inversion of ELS. The established fundamental view is that the medium energy electron spectra represent the total bulk density of states. (author)

Wigner-like crystallization of Anderson-localized electron systems with low electron densities

International Nuclear Information System (INIS)

Slutskin, A.A.; Kovtun, H.A.; Pepper, M.

2002-01-01

We consider an electron system under conditions of strong Anderson localization, taking into account interelectron long-range Coulomb repulsion. We establish that at sufficiently low electron densities and sufficiently low temperatures the Coulomb electron interaction brings about ordering of the Anderson-localized electrons into a structure that is close to an ideal (Wigner) crystal lattice, provided the dimension of the system is > 1. This Anderson-Wigner glass (AWG) is a new macroscopic electron state that, on the one hand, is beyond the conventional Fermi glass concept, and on the other hand, qualitatively differs from the known 'plain' Wigner glass (inherent in self-localized electron systems) in that the random slight electron displacements from the ideal crystal sites essentially depend on the electron density. With increasing electron density the AWG is found to turn into the plain Wigner glass or Fermi glass, depending on the width of the random spread of the electron levels. It is shown that the residual disorder of the AWG is characterized by a multi-valley ground-state degeneracy akin to that in a spin glass. Some general features of the AWG are discussed, and a new conduction mechanism of a creep type is predicted

3D Printed structural electronics: embedding and connecting electronic components into freeform electronic devices

NARCIS (Netherlands)

Maalderink, H.H.H.; Bruning, F.B.J.; Schipper, M.M.R. de; Werff, J.J.J. van der; Germs, W.W.C.; Remmers, J.J.C.; Meinders, E.R.

2018-01-01

The need for personalised and smart products drives the development of structural electronics with mass-customisation capability. A number of challenges need to be overcome in order to address the potential of complete free form manufacturing of electronic devices. One key challenge is the

3D Printed structural electronics : embedding and connecting electronic components into freeform electronic devices

NARCIS (Netherlands)

Maalderink, H.H.; Bruning, F.B.J.; de Schipper, M.R.; van der Werff, J.J.; Germs, W.C.; Remmers, J.J.C.; Meinders, E.R.

2018-01-01

The need for personalised and smart products drives the development of structural electronics with mass-customisation capability. A number of challenges need to be overcome in order to address the potential of complete free form manufacturing of electronic devices. One key challenge is the