Influence of Electric Fields and Conductivity on Pollen Tube Growth assessed via Electrical Lab-on-Chip

Science.gov (United States)

Agudelo, Carlos; Packirisamy, Muthukumaran; Geitmann, Anja

2016-01-01

Pollen tubes are polarly growing plant cells that are able to rapidly respond to a combination of chemical, mechanical, and electrical cues. This behavioural feature allows them to invade the flower pistil and deliver the sperm cells in highly targeted manner to receptive ovules in order to accomplish fertilization. How signals are perceived and processed in the pollen tube is still poorly understood. Evidence for electrical guidance in particular is vague and highly contradictory. To generate reproducible experimental conditions for the investigation of the effect of electric fields on pollen tube growth we developed an Electrical Lab-on-Chip (ELoC). Pollen from the species Camellia displayed differential sensitivity to electric fields depending on whether the entire cell or only its growing tip was exposed. The response to DC fields was dramatically higher than that to AC fields of the same strength. However, AC fields were found to restore and even promote pollen growth. Surprisingly, the pollen tube response correlated with the conductivity of the growth medium under different AC frequencies—consistent with the notion that the effect of the field on pollen tube growth may be mediated via its effect on the motion of ions. PMID:26804186

Nitric oxide participates in cold-inhibited Camellia sinensis pollen germination and tube growth partly via cGMP in vitro.

Directory of Open Access Journals (Sweden)

Yu-Hua Wang

Full Text Available Nitric oxide (NO plays essential roles in many biotic and abiotic stresses in plant development procedures, including pollen tube growth. Here, effects of NO on cold stress inhibited pollen germination and tube growth in Camellia sinensis were investigated in vitro. The NO production, NO synthase (NOS-like activity, cGMP content and proline (Pro accumulation upon treatment with NO scavenger cPTIO, NOS inhibitor L-NNA, NO donor DEA NONOate, guanylate cyclase (GC inhibitor ODQ or phosphodiesterase (PDE inhibitor Viagra at 25°C (control or 4°C were analyzed. Exposure to 4°C for 2 h reduced pollen germination and tube growth along with increase of NOS-like activity, NO production and cGMP content in pollen tubes. DEA NONOate treatment inhibited pollen germination and tube growth in a dose-dependent manner under control and reinforced the inhibition under cold stress, during which NO production and cGMP content promoted in pollen tubes. L-NNA and cPTIO markedly reduced the generation of NO induced by cold or NO donor along with partly reverse of cold- or NO donor-inhibited pollen germination and tube growth. Furthermore, ODQ reduced the cGMP content under cold stress and NO donor treatment in pollen tubes. Meanwhile, ODQ disrupted the reinforcement of NO donor on the inhibition of pollen germination and tube growth under cold condition. Additionally, Pro accumulation of pollen tubes was reduced by ODQ compared with that receiving NO donor under cold or control condition. Effects of cPTIO and L-NNA in improving cold-treated pollen germination and pollen tube growth could be lowered by Viagra. Moreover, the inhibitory effects of cPTIO and L-NNA on Pro accumulation were partly reversed by Viagra. These data suggest that NO production from NOS-like enzyme reaction decreased the cold-responsive pollen germination, inhibited tube growth and reduced Pro accumulation, partly via cGMP signaling pathway in C. sinensis.

The Apical Actin Fringe Contributes to Localized Cell Wall Deposition and Polarized Growth in the Lily Pollen Tube1[W][OPEN

Science.gov (United States)

Rounds, Caleb M.; Hepler, Peter K.; Winship, Lawrence J.

2014-01-01

In lily (Lilium formosanum) pollen tubes, pectin, a major component of the cell wall, is delivered through regulated exocytosis. The targeted transport and secretion of the pectin-containing vesicles may be controlled by the cortical actin fringe at the pollen tube apex. Here, we address the role of the actin fringe using three different inhibitors of growth: brefeldin A, latrunculin B, and potassium cyanide. Brefeldin A blocks membrane trafficking and inhibits exocytosis in pollen tubes; it also leads to the degradation of the actin fringe and the formation of an aggregate of filamentous actin at the base of the clear zone. Latrunculin B, which depolymerizes filamentous actin, markedly slows growth but allows focused pectin deposition to continue. Of note, the locus of deposition shifts frequently and correlates with changes in the direction of growth. Finally, potassium cyanide, an electron transport chain inhibitor, briefly stops growth while causing the actin fringe to completely disappear. Pectin deposition continues but lacks focus, instead being delivered in a wide arc across the pollen tube tip. These data support a model in which the actin fringe contributes to the focused secretion of pectin to the apical cell wall and, thus, to the polarized growth of the pollen tube. PMID:25037212

Gibberellin regulates pollen viability and pollen tube growth in rice.

Science.gov (United States)

Chhun, Tory; Aya, Koichiro; Asano, Kenji; Yamamoto, Eiji; Morinaka, Yoichi; Watanabe, Masao; Kitano, Hidemi; Ashikari, Motoyuki; Matsuoka, Makoto; Ueguchi-Tanaka, Miyako

2007-12-01

Gibberellins (GAs) play many biological roles in higher plants. We collected and performed genetic analysis on rice (Oryza sativa) GA-related mutants, including GA-deficient and GA-insensitive mutants. Genetic analysis of the mutants revealed that rice GA-deficient mutations are not transmitted as Mendelian traits to the next generation following self-pollination of F1 heterozygous plants, although GA-insensitive mutations are transmitted normally. To understand these differences in transmission, we examined the effect of GA on microsporogenesis and pollen tube elongation in rice using new GA-deficient and GA-insensitive mutants that produce semifertile flowers. Phenotypic analysis revealed that the GA-deficient mutant reduced pollen elongation1 is defective in pollen tube elongation, resulting in a low fertilization frequency, whereas the GA-insensitive semidominant mutant Slr1-d3 is mainly defective in viable pollen production. Quantitative RT-PCR revealed that GA biosynthesis genes tested whose mutations are transmitted to the next generation at a lower frequency are preferentially expressed after meiosis during pollen development, but expression is absent or very low before the meiosis stage, whereas GA signal-related genes are actively expressed before meiosis. Based on these observations, we predict that the transmission of GA-signaling genes occurs in a sporophytic manner, since the protein products and/or mRNA transcripts of these genes may be introduced into pollen-carrying mutant alleles, whereas GA synthesis genes are transmitted in a gametophytic manner, since these genes are preferentially expressed after meiosis.

Calreticulin is required for calcium homeostasis and proper pollen tube tip growth in Petunia

OpenAIRE

Suwi?ska, Anna; Was?g, Piotr; Zakrzewski, Przemys?aw; Lenartowska, Marta; Lenartowski, Robert

2017-01-01

Main conclusion Calreticulin is involved in stabilization of the tip-focused Ca 2+ gradient and the actin cytoskeleton arrangement and function that is required for several key processes driving Petunia pollen tube tip growth. Although the precise mechanism is unclear, stabilization of a tip-focused calcium (Ca2+) gradient seems to be critical for pollen germination and pollen tube growth. We hypothesize that calreticulin (CRT), a Ca2+-binding/buffering chaperone typically residing in the lum...

Perturbation Analysis of Calcium, Alkalinity and Secretion during Growth of Lily Pollen Tubes.

Science.gov (United States)

Winship, Lawrence J; Rounds, Caleb; Hepler, Peter K

2016-12-30

Pollen tubes grow by spatially and temporally regulated expansion of new material secreted into the cell wall at the tip of the tube. A complex web of interactions among cellular components, ions and small molecule provides dynamic control of localized expansion and secretion. Cross-correlation studies on oscillating lily ( Lilium formosanum Wallace) pollen tubes showed that an increase in intracellular calcium follows an increase in growth, whereas the increase in the alkaline band and in secretion both anticipate the increase in growth rate. Calcium, as a follower, is unlikely to be a stimulator of growth, whereas the alkaline band, as a leader, may be an activator. To gain further insight herein we reversibly inhibited growth with potassium cyanide (KCN) and followed the re-establishment of calcium, pH and secretion patterns as growth resumed. While KCN markedly slows growth and causes the associated gradients of calcium and pH to sharply decline, its removal allows growth and vital processes to fully recover. The calcium gradient reappears before growth restarts; however, it is preceded by both the alkaline band and secretion, in which the alkaline band is slightly advanced over secretion. Thus the pH gradient, rather than the tip-focused calcium gradient, may regulate pollen tube growth.

Perturbation Analysis of Calcium, Alkalinity and Secretion during Growth of Lily Pollen Tubes

Directory of Open Access Journals (Sweden)

Lawrence J. Winship

2016-12-01

Full Text Available Pollen tubes grow by spatially and temporally regulated expansion of new material secreted into the cell wall at the tip of the tube. A complex web of interactions among cellular components, ions and small molecule provides dynamic control of localized expansion and secretion. Cross-correlation studies on oscillating lily (Lilium formosanum Wallace pollen tubes showed that an increase in intracellular calcium follows an increase in growth, whereas the increase in the alkaline band and in secretion both anticipate the increase in growth rate. Calcium, as a follower, is unlikely to be a stimulator of growth, whereas the alkaline band, as a leader, may be an activator. To gain further insight herein we reversibly inhibited growth with potassium cyanide (KCN and followed the re-establishment of calcium, pH and secretion patterns as growth resumed. While KCN markedly slows growth and causes the associated gradients of calcium and pH to sharply decline, its removal allows growth and vital processes to fully recover. The calcium gradient reappears before growth restarts; however, it is preceded by both the alkaline band and secretion, in which the alkaline band is slightly advanced over secretion. Thus the pH gradient, rather than the tip-focused calcium gradient, may regulate pollen tube growth.

De novo post-pollen mitosis II tobacco pollen tube transcriptome

Czech Academy of Sciences Publication Activity Database

Hafidh, Said; Breznenová, Katarína; Honys, David

2012-01-01

Roč. 7, č. 8 (2012), s. 918-921 ISSN 1559-2316 R&D Projects: GA ČR GPP501/11/P321; GA ČR GA522/09/0858 Institutional research plan: CEZ:AV0Z50380511 Keywords : de novo pollen tube transcriptome * male gametophyte development * pollen tube growth Subject RIV: ED - Physiology

Pectin and the role of the physical properties of the cell wall in pollen tube growth of Solanum chacoense.

Science.gov (United States)

Parre, Elodie; Geitmann, Anja

2005-02-01

The cell wall is one of the structural key players regulating pollen tube growth, since plant cell expansion depends on an interplay between intracellular driving forces and the controlled yielding of the cell wall. Pectin is the main cell wall component at the growing pollen tube apex. We therefore assessed its role in pollen tube growth and cytomechanics using the enzymes pectinase and pectin methyl esterase (PME). Pectinase activity was able to stimulate pollen germination and tube growth at moderate concentrations whereas higher concentrations caused apical swelling or bursting in Solanum chacoense Bitt. pollen tubes. This is consistent with a modification of the physical properties of the cell wall affecting its extensibility and thus the growth rate, as well as its capacity to withstand turgor. To prove that the enzyme-induced effects were due to the altered cell wall mechanics, we subjected pollen tubes to micro-indentation experiments. We observed that cellular stiffness was reduced and visco-elasticity increased in the presence of pectinase. These are the first mechanical data that confirm the influence of the amount of pectins in the pollen tube cell wall on the physical parameters characterizing overall cellular architecture. Cytomechanical data were also obtained to analyze the role of the degree of pectin methyl-esterification, which is known to exhibit a gradient along the pollen tube axis. This feature has frequently been suggested to result in a gradient of the physical properties characterizing the cell wall and our data provide, for the first time, mechanical support for this concept. The gradient in cell wall composition from apical esterified to distal de-esterified pectins seems to be correlated with an increase in the degree of cell wall rigidity and a decrease of visco-elasticity. Our mechanical approach provides new insights concerning the mechanics of pollen tube growth and the architecture of living plant cells.

Emerging roles for microtubules in angiosperm pollen tube growth highlight new research cues

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Alessandra eMoscatelli

2015-02-01

Full Text Available In plants, actin filaments have an important role in organelle movement and cytoplasmic streaming. Otherwise microtubules have a role in restricting organelles to specific areas of the cell and in maintaining organelle morphology. In somatic plant cells, microtubules also participate in cell division and morphogenesis, allowing cells to take their definitive shape in order to perform specific functions. In the latter case, microtubules influence assembly of the cell wall, controlling the delivery of enzymes involved in cellulose synthesis and of wall modulation material to the proper sites.In angiosperm pollen tubes, organelle movement is generally attributed to the acto-myosin system, the main role of which is in distributing organelles in the cytoplasm and in carrying secretory vesicles to the apex for polarized growth. Recent data on membrane trafficking suggests a role of microtubules in fine delivery and repositioning of vesicles to sustain pollen tube growth. This review examines the role of microtubules in secretion and endocytosis, highlighting new research cues regarding cell wall construction and pollen tube-pistil crosstalk, that help unravel the role of microtubules in polarized growth.

The apical actin fringe contributes to localized cell wall deposition and polarized growth in the lily pollen tube.

Science.gov (United States)

Rounds, Caleb M; Hepler, Peter K; Winship, Lawrence J

2014-09-01

In lily (Lilium formosanum) pollen tubes, pectin, a major component of the cell wall, is delivered through regulated exocytosis. The targeted transport and secretion of the pectin-containing vesicles may be controlled by the cortical actin fringe at the pollen tube apex. Here, we address the role of the actin fringe using three different inhibitors of growth: brefeldin A, latrunculin B, and potassium cyanide. Brefeldin A blocks membrane trafficking and inhibits exocytosis in pollen tubes; it also leads to the degradation of the actin fringe and the formation of an aggregate of filamentous actin at the base of the clear zone. Latrunculin B, which depolymerizes filamentous actin, markedly slows growth but allows focused pectin deposition to continue. Of note, the locus of deposition shifts frequently and correlates with changes in the direction of growth. Finally, potassium cyanide, an electron transport chain inhibitor, briefly stops growth while causing the actin fringe to completely disappear. Pectin deposition continues but lacks focus, instead being delivered in a wide arc across the pollen tube tip. These data support a model in which the actin fringe contributes to the focused secretion of pectin to the apical cell wall and, thus, to the polarized growth of the pollen tube. © 2014 American Society of Plant Biologists. All Rights Reserved.

Gene expression profile indicates involvement of NO in Camellia sinensis pollen tube growth at low temperature.

Science.gov (United States)

Pan, Junting; Wang, Weidong; Li, Dongqin; Shu, Zaifa; Ye, Xiaoli; Chang, Pinpin; Wang, Yuhua

2016-10-18

Nitric oxide (NO) functions as a critical signaling molecule in the low-temperature stress responses in plants, including polarized pollen tube growth in Camellia sinensis. Despite this, the potential mechanisms underlying the participation of NO in pollen tube responses to low temperature remain unclear. Here, we investigate alterations to gene expression in C. sinensis pollen tubes exposed to low-temperature stress and NO using RNA-Seq technology, in order to find the potential candidate genes related to the regulation of pollen tube elongation by NO under low-temperature stress. Three libraries were generated from C. sinensis cv. 'Longjingchangye' pollen tubes cultured at 25 °C (CsPT-CK) and 4 °C (CsPT-LT) or with 25 μM DEA NONOate (CsPT-NO). The number of unigenes found for the three biological replications were 39,726, 40,440 and 41,626 for CsPT-CK; 36,993, 39,070 and 39,439 for CsPT-LT; and 39,514, 38,298 and 39,061 for CsPT-NO. A total of 36,097 unique assembled and annotated sequences from C. sinensis pollen tube reads were found in a BLAST search of the following databases: NCBI non-redundant nucleotide, Swiss-prot protein, Kyoto Encyclopedia of Genes and Genomes, Cluster of Orthologous Groups of proteins, and Gene Ontology. The absolute values of log 2 Ratio > 1 and probability > 0.7 were used as the thresholds for significantly differential gene expression, and 766, 497 and 929 differentially expressed genes (DEGs) were found from the comparison analyses of the CK-VS-LT, CK-VS-NO and LT-VS-NO libraries, respectively. Genes related to metabolism and signaling pathways of plant hormones, transcription factors (TFs), vesicle polarized trafficking, cell wall biosynthesis, the ubiquitination machinery of the ubiquitin system and species-specific secondary metabolite pathways were mainly observed in the CK-VS-LT and CK-VS-NO libraries. Differentially expressed unigenes related to the inhibition of C. sinensis pollen tube growth under low

Male-female crosstalk during pollen germination, tube growth and guidance, and double fertilization.

Science.gov (United States)

Dresselhaus, Thomas; Franklin-Tong, Noni

2013-07-01

Sperm cells of flowering plants are non-motile and thus require transportation to the egg apparatus via the pollen tube to execute double fertilization. During its journey, the pollen tube interacts with various sporophytic cell types that support its growth and guide it towards the surface of the ovule. The final steps of tube guidance and sperm delivery are controlled by the cells of the female gametophyte. During fertilization, cell-cell communication events take place to achieve and maximize reproductive success. Additional layers of crosstalk exist, including self-recognition and specialized processes to prevent self-fertilization and consequent inbreeding. In this review, we focus on intercellular communication between the pollen grain/pollen tube including the sperm cells with the various sporophytic maternal tissues and the cells of the female gametophyte. Polymorphic-secreted peptides and small proteins, especially those belonging to various subclasses of small cysteine-rich proteins (CRPs), reactive oxygen species (ROS)/NO signaling, and the second messenger Ca(2+), play center stage in most of these processes.

Pollen tube growth test (PTGT) in environmental biomonitoring and predictive radiation biology studies: problem and prospect

International Nuclear Information System (INIS)

Pandey, Devi D.

2012-01-01

In Environmental and Human Bio monitoring studies of Hazardous xenobiotics over living system particularly at cell level, it is desirable to have easy and sensitive test system like Cell Viability assay, MNT, Cell Culture photo toxicity Test, PTGT etc. Out of these the PTGT quite better than other because the in vitro culture of pollen grain can provides a sensitive indication of toxicity at cellular level, since germination and growth of pollen tube will inhibited in presence of toxic substance like DDT, Heavy metal, even Radionuclide's. This test system is easy, economical and widely accepted through out world. In PTGT pollen tube never containing Chloroplast or other plastids so pollen tube resembles animals more than a plant organ and is therefore also a suitable as model for Genotoxicity Assessment of compounds harmful to animal and humans. Lack of plastids in PT, PTGT will not identify the toxic effect of compounds that targets Non cyclic and cyclic photoposphorylation of photosynthesis. This test system valid in International Toxicity Testing Protocol. But this method is time consuming and problem in measurement of pollen tube growing in a culture medium became usually bent and make measurement difficult. Other disadvantage of this method is requirement of DMSO to dissolve test substance of low water suitability in culture medium. DMSO shown to have no effect on PTG at Concentration not more than 1% but some extent interfere with results. Values of PTG are quantified in ED50/IC50 that is the concentration of test compounds that reduces pollen tube growth to 50% of control. So PTGT could be very sensitive and easy to assess in common lab in International way. (author)

Interference of the Histone Deacetylase Inhibits Pollen Germination and Pollen Tube Growth in Picea wilsonii Mast.

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Yaning Cui

Full Text Available Histone deacetylase (HDAC is a crucial component in the regulation of gene expression in various cellular processes in animal and plant cells. HDAC has been reported to play a role in embryogenesis. However, the effect of HDAC on androgamete development remains unclear, especially in gymnosperms. In this study, we used the HDAC inhibitors trichostatin A (TSA and sodium butyrate (NaB to examine the role of HDAC in Picea wilsonii pollen germination and pollen tube elongation. Measurements of the tip-focused Ca2+ gradient revealed that TSA and NaB influenced this gradient. Immunofluorescence showed that actin filaments were disrupted into disorganized fragments. As a result, the vesicle trafficking was disturbed, as determined by FM4-64 labeling. Moreover, the distribution of pectins and callose in cell walls was significantly altered in response to TSA and NaB. Our results suggest that HDAC affects pollen germination and polarized pollen tube growth in Picea wilsonii by affecting the intracellular Ca2+ concentration gradient, actin organization patterns, vesicle trafficking, as well as the deposition and configuration of cell wall components.

Combination of U.V.-B and ozone reduces pollen tube growth more than either stress alone

International Nuclear Information System (INIS)

Feder, W.A.; Shrier, R.

1990-01-01

The rate of in vitro Nicotiana tabacum L. “Bel-W3” pollen tube growth was reduced 62 and 44%, respectively, when pollen tubes were exposed to 120 ppb ozone (O 3 ) for 3 hr or 300 μW/cm 2 ultraviolet-B (u.v.-B) radiation for 30 min. Petunia hybrida Vilm. “White Cascade” pollen tube growth was reduced 34 and 59%, respectively, upon exposure to O 3 or u.v.-B at the above doses. The combination of u.v.-B at 300 μW/cm 2 for 30 min, followed by O 3 at 120 ppb for 3 hr, reduced pollen tube growth by 79% for “Bel-W3” and 75% for “White Cascade”. The effect appeared to be additive, implying that different target areas may be affected by the two stressors. In the Northeast, plants are exposed to both u.v.-B and O 3 during the normal growing season. This may result in an unexpectedly higher stress on the reproductive system than had been previously suspected based on these two stressors acting individually. (author)

UV dosimetry in pollen of Pinus silvestris and stimulation studies of pollen tube growth after irradiation with UV and ionizing radiations

International Nuclear Information System (INIS)

Seibold, H.W.

1976-01-01

Pollen tube growth after exposure to UV- and ionizing radiation was investigated in Pinus silvestris as a function of different parameters. The preconditions for this are an exact UV dosimetry and the conversion of the UV dose of [erg] into [rad]. In spite of the fact that the calculation methods are theoretically already well known, the experimental determination of the absorbed energy dose, in particular the absorption factors, was complicated by the morphological structure of the pollen. The total-irradiation experiments showed that the stimulation and inhibition of pollen tube growth is highly dependent on the dose/dose rate region chosen. Stimulation is highly dependent on the dose rate after UV irradiation as well as after exposure to ionizing radiation. When the dose rates are very small, the values are practically the same as in non-irradiated controls; with increasing doses rate, stimulation increases, whereas at very high dose rates only growth inhibition is observed. After exposure to ionizing radiation, the quantum energy or wavelength of the radiation has no effect on tube growth; after UV irradiation, on the other hand, there is hardly any stimulation at short wavelengths. As these observations were not sufficient for drawing conclusions on the site of the stimulatory action, partial UV exposure with separate irradiation of the two nuclei and the cytoplasm was also carried out. Stimulation was found in each of the three irradiation sites; although nuclei and cytoplasma react differently and also differ in the initial reaction stages, there is always an anhancement of pollen tube growth. These findings are compared with some of the current hypotheses for an explanation of the stimulatory effect. (orig.) [de

Arabidopsis COBRA-LIKE 10, a GPI-anchored protein, mediates directional growth of pollen tubes

NARCIS (Netherlands)

Li, S.; Ge, F.R.; Xu, M.; Zhao, X.Y.; Huang, G.Q.; Zhou, L.Z.; Wang, J.G.; Kombrink, A.; McCormick, S.; Zhang, X.S.; Zhang, Y.

2013-01-01

Successful reproduction of flowering plants requires constant communication between female tissues and growing pollen tubes. Female cells secrete molecules and peptides as nutrients or guidance cues for fast and directional tube growth, which is executed by dynamic changes of intracellular

A plant plasma membrane Ca2+ pump is required for normal pollen tube growth and fertilization

DEFF Research Database (Denmark)

Schiøtt, Morten; Romanowsky, Shawn M; Bækgaard, Lone

2004-01-01

Ca(2+) signals are thought to play important roles in plant growth and development, including key aspects of pollen tube growth and fertilization. The dynamics of a Ca(2+) signal are largely controlled by influx (through channels) and efflux (through pumps and antiporters). The Arabidopsis genome...... and a high frequency of aborted fertilization, resulting in a >80% reduction in seed set. These findings identify a plasma membrane Ca(2+) transporter as a key regulator of pollen development and fertilization in flowering plants.......Ca(2+) signals are thought to play important roles in plant growth and development, including key aspects of pollen tube growth and fertilization. The dynamics of a Ca(2+) signal are largely controlled by influx (through channels) and efflux (through pumps and antiporters). The Arabidopsis genome......-inducing) plasmid that is transferred to plant cells] gene disruptions of ACA9 were found to result in partial male sterility. Complementation was observed by using a ACA9-yellow fluorescence protein (YFP) fusion that displayed plasma membrane localization. Mutant aca9 pollen displayed a reduced growth potential...

Receptor-like kinases as surface regulators for RAC/ROP-mediated pollen tube growth and interaction with the pistil

Science.gov (United States)

Zou, Yanjiao; Aggarwal, Mini; Zheng, Wen-Guang; Wu, Hen-Ming; Cheung, Alice Y.

2011-01-01

Background RAC/ROPs are RHO-type GTPases and are known to play diverse signalling roles in plants. Cytoplasmic RAC/ROPs are recruited to the cell membrane and activated in response to extracellular signals perceived and mediated by cell surface-located signalling assemblies, transducing the signals to regulate cellular processes. More than any other cell types in plants, pollen tubes depend on continuous interactions with an extracellular environment produced by their surrounding tissues as they grow within the female organ pistil to deliver sperm to the female gametophyte for fertilization. Scope We review studies on pollen tube growth that provide compelling evidence indicating that RAC/ROPs are crucial for regulating the cellular processes that underlie the polarized cell growth process. Efforts to identify cell surface regulators that mediate extracellular signals also point to RAC/ROPs being the molecular switches targeted by growth-regulating female factors for modulation to mediate pollination and fertilization. We discuss a large volume of work spanning more than two decades on a family of pollen-specific receptor kinases and some recent studies on members of the FERONIA family of receptor-like kinases (RLKs). Significance The research described shows the crucial roles that two RLK families play in transducing signals from growth regulatory factors to the RAC/ROP switch at the pollen tube apex to mediate and target pollen tube growth to the female gametophyte and signal its disintegration to achieve fertilization once inside the female chamber. PMID:22476487

Two-peaked dose curves for irradiated pollen growth

International Nuclear Information System (INIS)

Andrejchenko, S.V.; Grodzinskij, D.M.

1992-01-01

The effect of γ-radiation on growth activity of bicellular pollen of hybrid petunia has been investigated. Irradiation of pollen with doses of 5 to 70 Gy increases the pollen tube growth in an artificial culture medium. As the radiation dose increases the germination ability of pollen gradually decreases and the mean pollen tube length shortens, which is accompanied by the suppression of the generative cell division into spermia and inhibition of the unscheduled incorporation of labelled thymidine into DNA. With radiation doses of 1200 to 1700 Gy some pollen tubes grow intensively. It is suggested that the phenomenon observed lays the basis for the gametic transformation

Anther response to high-temperature stress during development and pollen thermotolerance heterosis as revealed by pollen tube growth and in vitro pollen vigor analysis in upland cotton.

Science.gov (United States)

Song, Guicheng; Wang, Miaomiao; Zeng, Bin; Zhang, Jing; Jiang, Chenliang; Hu, Qirui; Geng, Guangtao; Tang, Canming

2015-05-01

Pollen tube growth in styles was strongly inhibited by temperature above 35 °C, and the yield of cotton decreased because of the adverse effect of high temperatures during square development. High-temperature stress during flowering influences the square development of upland cotton (Gossypium hirsutum L.) and cotton yield. Although it is well known that square development is sensitive to high temperature, high-temperature sensitive stages of square development and the effects of high temperature on pollen tube growth in the styles are unknown. The effect of high temperature on anther development corresponding to pollen vigor is unknown during anther development. The objectives of this study were to identify the stages of square development that are sensitive to high temperatures (37/30 and 40/34 °C), to determine whether the abnormal development of squares influenced by high temperature is responsible for the variation in the in vitro germination percent of pollen grains at anthesis, to identify the effect of high temperature on pollen germination in the styles, and to determine pollen thermotolerance heterosis. Our results show that the stages from the sporogenous cell to tetrad stage (square length styles was strongly inhibited by temperature above 35 °C, and the yield of cotton decreased because of the effect of high temperature during square development. The thermotolerance of hybrid F1 pollen showed heterosis, and pollen viability could be used as a criterion for screening for high-temperature tolerance cultivars. These results can be used in breeding to develop new cotton cultivars that can withstand high-temperature conditions, particularly in a future warmer climate.

Pollen tube branching in the ovary of five species of Oenothera

Directory of Open Access Journals (Sweden)

Renata Śnieżko

2014-01-01

Full Text Available Flowers of Oenothera hookeri Torr. et Gray, Oe. brevistylis and Oe. lamarkiana de Vries were pollinated after anthesis by insects. Oe. biennis L., Oe. suaveolens Desf and sulfurea were selfpollinated in the buds. Pollen morphology was slightly different: Oe. hookeri have regular, triporated pollen, often germinating through two pores; in Oe. suaveolens many pollen grains had callose patches on the intine; in Oe. brevistylis tetraporated pollen were more often than in other species; in Oe. lamarckiana many pollen grains were empty; in Oe. biennis and Oe. suaveolens pollen grain size and viability varied. The pollen tube growth and fertilization were similar in 5 species and can be considered as typical for Oenothera. In the ovary pollen tubes branched and changed their growth direction. Near micropyle they formed short branches to the inner integument. In the nucellus the pollen tube became swollen.

Defensin-like ZmES4 mediates pollen tube burst in maize via opening of the potassium channel KZM1.

Directory of Open Access Journals (Sweden)

Suseno Amien

2010-06-01

Full Text Available In contrast to animals and lower plant species, sperm cells of flowering plants are non-motile and are transported to the female gametes via the pollen tube, i.e. the male gametophyte. Upon arrival at the female gametophyte two sperm cells are discharged into the receptive synergid cell to execute double fertilization. The first players involved in inter-gametophyte signaling to attract pollen tubes and to arrest their growth have been recently identified. In contrast the physiological mechanisms leading to pollen tube burst and thus sperm discharge remained elusive. Here, we describe the role of polymorphic defensin-like cysteine-rich proteins ZmES1-4 (Zea mays embryo sac from maize, leading to pollen tube growth arrest, burst, and explosive sperm release. ZmES1-4 genes are exclusively expressed in the cells of the female gametophyte. ZmES4-GFP fusion proteins accumulate in vesicles at the secretory zone of mature synergid cells and are released during the fertilization process. Using RNAi knock-down and synthetic ZmES4 proteins, we found that ZmES4 induces pollen tube burst in a species-preferential manner. Pollen tube plasma membrane depolarization, which occurs immediately after ZmES4 application, as well as channel blocker experiments point to a role of K(+-influx in the pollen tube rupture mechanism. Finally, we discovered the intrinsic rectifying K(+ channel KZM1 as a direct target of ZmES4. Following ZmES4 application, KZM1 opens at physiological membrane potentials and closes after wash-out. In conclusion, we suggest that vesicles containing ZmES4 are released from the synergid cells upon male-female gametophyte signaling. Subsequent interaction between ZmES4 and KZM1 results in channel opening and K(+ influx. We further suggest that K(+ influx leads to water uptake and culminates in osmotic tube burst. The species-preferential activity of polymorphic ZmES4 indicates that the mechanism described represents a pre-zygotic hybridization

Defensin-Like ZmES4 Mediates Pollen Tube Burst in Maize via Opening of the Potassium Channel KZM1

Science.gov (United States)

Márton, Mihaela L.; Debener, Thomas; Geiger, Dietmar; Becker, Dirk; Dresselhaus, Thomas

2010-01-01

In contrast to animals and lower plant species, sperm cells of flowering plants are non-motile and are transported to the female gametes via the pollen tube, i.e. the male gametophyte. Upon arrival at the female gametophyte two sperm cells are discharged into the receptive synergid cell to execute double fertilization. The first players involved in inter-gametophyte signaling to attract pollen tubes and to arrest their growth have been recently identified. In contrast the physiological mechanisms leading to pollen tube burst and thus sperm discharge remained elusive. Here, we describe the role of polymorphic defensin-like cysteine-rich proteins ZmES1-4 (Zea mays embryo sac) from maize, leading to pollen tube growth arrest, burst, and explosive sperm release. ZmES1-4 genes are exclusively expressed in the cells of the female gametophyte. ZmES4-GFP fusion proteins accumulate in vesicles at the secretory zone of mature synergid cells and are released during the fertilization process. Using RNAi knock-down and synthetic ZmES4 proteins, we found that ZmES4 induces pollen tube burst in a species-preferential manner. Pollen tube plasma membrane depolarization, which occurs immediately after ZmES4 application, as well as channel blocker experiments point to a role of K+-influx in the pollen tube rupture mechanism. Finally, we discovered the intrinsic rectifying K+ channel KZM1 as a direct target of ZmES4. Following ZmES4 application, KZM1 opens at physiological membrane potentials and closes after wash-out. In conclusion, we suggest that vesicles containing ZmES4 are released from the synergid cells upon male-female gametophyte signaling. Subsequent interaction between ZmES4 and KZM1 results in channel opening and K+ influx. We further suggest that K+ influx leads to water uptake and culminates in osmotic tube burst. The species-preferential activity of polymorphic ZmES4 indicates that the mechanism described represents a pre-zygotic hybridization barrier and may be a

Unusual behavior of growing pollen tubes in the ovary of plum culture (Prunus domestica L.

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Đorđević Milena

2010-01-01

Full Text Available Unusual behavior of growing pollen tubes in different combinations of pollination was observed in the ovary of the plum (Prunus domestica L. cv 'Čačanska Lepotica'. It primarily refers to several issues, i.e. the curling up of pollen tubes within the micropyle, the growth of two pollen tubes into the nucellus of an ovule, the occurrence of a bundle above the nucellar cap and fluorescence of the part of the embryo sac containing the egg apparatus. Upon the growth of pollen tubes into the nucellus of the ovule, subsequently penetrating pollen tubes form a bundle either above the micropyle entrance or above the nucellus. Branching and bending of pollen tubes by 180o upon their growth into the micropyle was also observed.

Exogenous γ-aminobutyric acid (GABA) affects pollen tube growth via modulating putative Ca2+-permeable membrane channels and is coupled to negative regulation on glutamate decarboxylase

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Yu, Guang-Hui; Zou, Jie; Feng, Jing; Peng, Xiong-Bo; Wu, Ju-You; Wu, Ying-Liang; Palanivelu, Ravishankar; Sun, Meng-Xiang

2014-01-01

γ-Aminobutyric acid (GABA) is implicated in pollen tube growth, but the molecular and cellular mechanisms that it mediates are largely unknown. Here, it is shown that exogenous GABA modulates putative Ca2+-permeable channels on the plasma membranes of tobacco pollen grains and pollen tubes. Whole-cell voltage-clamp experiments and non-invasive micromeasurement technology (NMT) revealed that the influx of Ca2+ increases in pollen tubes in response to exogenous GABA. It is also demonstrated that glutamate decarboxylase (GAD), the rate-limiting enzyme of GABA biosynthesis, is involved in feedback controls of Ca2+-permeable channels to fluctuate intracellular GABA levels and thus modulate pollen tube growth. The findings suggest that GAD activity linked with Ca2+-permeable channels relays an extracellular GABA signal and integrates multiple signal pathways to modulate tobacco pollen tube growth. Thus, the data explain how GABA mediates the communication between the style and the growing pollen tubes. PMID:24799560

EXO70C2 is a key regulatory factor for optimal tip growth of pollen

KAUST Repository

Synek, Lukas

2017-03-30

The exocyst, an eukaryotic tethering complex, co-regulates targeted exocytosis as an effector of small GTPases in polarized cell growth. In land plants, several exocyst subunits are encoded by double or triple paralogs, culminating in tens of EXO70 paralogs. Out of 23 Arabidopsis EXO70 isoforms, we analyzed seven isoforms expressed in pollen. Genetic and microscopic analyses of single mutants in EXO70A2, C1, C2, F1, H3, H5, and H6 genes revealed that only a loss-of-function EXO70C2 allele resulted in a significant male-specific transmission defect (segregation 40%:51%:9%) due to aberrant pollen tube growth. Mutant pollen tubes grown in vitro exhibited enhanced growth rate and a decreased thickness of the tip cell wall, causing tip bursts. However, exo70C2 pollen tubes could frequently recover and restart their speedy elongation, resulting in a repetitive stop-and-go growth dynamics. A pollen-specific depletion of the closest paralog, EXO70C1, using ami-RNA in the exo70C2 mutant background resulted in a complete pollen-specific transmission defect, suggesting redundant functions of EXO70C1 and EXO70C2. Both EXO70C1 and EXO70C2, GFP-tagged and expressed under their native promoters, localized in the cytoplasm of pollen grains, pollen tubes, and also root trichoblast cells. Expression of EXO70C2-GFP complemented aberrant growth of exo70C2 pollen tubes. The absent EXO70C2 interactions with core exocyst subunits in the yeast two-hybrid assay, cytoplasmic localization, and genetic effect suggest an unconventional EXO70 function possibly as a regulator of exocytosis outside the exocyst complex. In conclusion, EXO70C2 is a novel factor contributing to the regulation of optimal tip growth of Arabidopsis pollen tubes.

Segmentation of Pollen Tube Growth Videos Using Dynamic Bi-Modal Fusion and Seam Carving.

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Tambo, Asongu L; Bhanu, Bir

2016-05-01

The growth of pollen tubes is of significant interest in plant cell biology, as it provides an understanding of internal cell dynamics that affect observable structural characteristics such as cell diameter, length, and growth rate. However, these parameters can only be measured in experimental videos if the complete shape of the cell is known. The challenge is to accurately obtain the cell boundary in noisy video images. Usually, these measurements are performed by a scientist who manually draws regions-of-interest on the images displayed on a computer screen. In this paper, a new automated technique is presented for boundary detection by fusing fluorescence and brightfield images, and a new efficient method of obtaining the final cell boundary through the process of Seam Carving is proposed. This approach takes advantage of the nature of the fusion process and also the shape of the pollen tube to efficiently search for the optimal cell boundary. In video segmentation, the first two frames are used to initialize the segmentation process by creating a search space based on a parametric model of the cell shape. Updates to the search space are performed based on the location of past segmentations and a prediction of the next segmentation.Experimental results show comparable accuracy to a previous method, but significant decrease in processing time. This has the potential for real time applications in pollen tube microscopy.

Incompatible pollen tubes in the plum style and their impact on fertilization success

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Đorđević Milena

2014-01-01

Full Text Available The pistils of plum (Prunus domestica L. cv. ‘Čačanska Lepotica’ were self- and cross-pollinated in order to investigate occurrence of incompatible pollen tubes in the style, and their impact on fertilization success. The investigation also included open pollination variant. The highest percentage of these stopped the growth in the upper third of the style. Under cross-pollination variant, 15.4% and 12.1% of pollen tubes observed in the upper part of the style in the first and the second years of study, respectively, were found incompatible. In view of the above parameters, in the self- pollination variant, 15.0% and 17.0% of pollen tubes were found incompatible by years. As for the open pollination, percentages of incompatible pollen tubes in the upper part of the style by years were 14.0% and 14.4%, respectively. The occurrence of incompatible pollen tubes did not influence the fertilization success in these pollination variants. [Projekat Ministarstva nauke Republike Srbije, br. TR31064-Development and preservation of genetic potential of temperate zone fruits

Pyruvate decarboxylase provides growing pollen tubes with a competitive advantage in petunia.

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Gass, Nathalie; Glagotskaia, Tatiana; Mellema, Stefan; Stuurman, Jeroen; Barone, Mario; Mandel, Therese; Roessner-Tunali, Ute; Kuhlemeier, Cris

2005-08-01

Rapid pollen tube growth places unique demands on energy production and biosynthetic capacity. The aim of this work is to understand how primary metabolism meets the demands of such rapid growth. Aerobically grown pollen produce ethanol in large quantities. The ethanolic fermentation pathway consists of two committed enzymes: pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH). Because adh mutations do not affect male gametophyte function, the obvious question is why pollen synthesize an abundant enzyme if they could do just as well without. Using transposon tagging in Petunia hybrida, we isolated a null mutant in pollen-specific Pdc2. Growth of the mutant pollen tubes through the style is reduced, and the mutant allele shows reduced transmission through the male, when in competition with wild-type pollen. We propose that not ADH but rather PDC is the critical enzyme in a novel, pollen-specific pathway. This pathway serves to bypass pyruvate dehydrogenase enzymes and thereby maintain biosynthetic capacity and energy production under the unique conditions prevailing during pollen-pistil interaction.

Radiation-induced pollen germination, tube growth, its localized cytochemical constituents, fruit set and fruit size in alkaloid yielding species Solanum torvum L

International Nuclear Information System (INIS)

Chauhan, Y.S.; Katiyar, S.R.

1990-01-01

The volume of pollen, total number of pollen/flower, the percent of pollen germination and tube growth of long-styled flower were higher than the short-styled flowers in S. torvum. In addition, the pollination studies were conducted among the four selected sets for optimum fruit set investigation. Fruit set was not seen in both the first and second sets (female shorts-short male and female short-long male). However, the maximum fruit set was obtained in the fourth set (female long-male long). Pollen grains of long-styled flowers irradiated with 1-800 krad were germinated in the basal medium. The percent of pollen germination and the tube growth was stimulated over the control with 1 and 50 krad dose exposures, but increasing dose rates inhibited both the above processes. Utilization of insoluble polysaccharides, and the synthesis of RNA and protein were enhanced over the control with the effect of 50 krad. The higher (800 krad) dose exposures inhibited all the above cytochemical constituents. Various dose-treated pollens were used to pollinate the stigma surface of the long-styled flowers. The fruit set, fruit volume, fresh and dry weight of fruits, and the number of seed set/fruit, were enhanced over the control by 1 and 50 krad, while the higher doses caused inhibitory effect. Interestingly, the fruit set was not caused by radiation doses 400 krad and above. (author)

Molecular evidence that rough endoplasmic reticulum is the site of calreticulin translation in Petunia pollen tubes growing in vitro.

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Suwińska, Anna; Lenartowski, Robert; Smoliński, Dariusz Jan; Lenartowska, Marta

2015-07-01

In germinating pollen grains and growing pollen tubes, CRT is translated on ER membrane-bound ribosomes in the regions where its activity is required for stabilization of tip-focused Ca (2+) gradient. Pollen tube growth requires coordination of signaling, exocytosis, and actin cytoskeletal organization. Many of these processes are thought to be controlled by finely tuned regulation of cytoplasmic Ca(2+) in discrete regions of the tube cytoplasm. Most notably, a mechanism must function to maintain a steep gradient of Ca(2+) that exists at the tip of growing pollen tube. Several pieces of evidence point to calreticulin (CRT) as a key Ca(2+)-binding/-buffering protein involved in pollen germination and pollen tube growth. We previously hypothesized that in germinating pollen and growing tubes, CRT is translated on the ribosomes associated with endoplasmic reticulum (ER) in the regions where its activity might be required. In this report, we have addressed this idea by identifying the sites where CRT mRNA, CRT protein, 18S rRNA, and rough ER are localized in Petunia pollen tubes. We observed all four components in the germinal aperture of pollen grains and in subapical regions of elongating tubes. These results seem to support our idea that CRT is translated on ER membrane-bound ribosomes during pollen germination and pollen tube growth. In elongated pollen tubes, we found CRT mainly localized in the subapical zone, where ER and Golgi stacks are abundant. In eukaryotic cells, these organelles serve as mobile intracellular stores of easily releasable Ca(2+), which can be buffered by proteins such as CRT. Therefore, we postulate that subapical-localized CRT is involved in pollen tube growth by maintaining the stable tip-focused Ca(2+) gradient and thus modulating local Ca(2+) concentration within the tube cytoplasm.

Transcriptional evidence for inferred pattern of pollen tube-stigma metabolic coupling during pollination.

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Xun Yue

Full Text Available It is difficult to derive all qualitative proteomic and metabolomic experimental data in male (pollen tube and female (pistil reproductive tissues during pollination because of the limited sensitivity of current technology. In this study, genome-scale enzyme correlation network models for plants (Arabidopsis/maize were constructed by analyzing the enzymes and metabolic routes from a global perspective. Then, we developed a data-driven computational pipeline using the "guilt by association" principle to analyze the transcriptional coexpression profiles of enzymatic genes in the consecutive steps for metabolic routes in the fast-growing pollen tube and stigma during pollination. The analysis identified an inferred pattern of pollen tube-stigma ethanol coupling. When the pollen tube elongates in the transmitting tissue (TT of the pistil, this elongation triggers the mobilization of energy from glycolysis in the TT cells of the pistil. Energy-rich metabolites (ethanol are secreted that can be taken up by the pollen tube, where these metabolites are incorporated into the pollen tube's tricarboxylic acid (TCA cycle, which leads to enhanced ATP production for facilitating pollen tube growth. In addition, our analysis also provided evidence for the cooperation of kaempferol, dTDP-alpha-L-rhamnose and cell-wall-related proteins; phosphatidic-acid-mediated Ca2+ oscillations and cytoskeleton; and glutamate degradation IV for γ-aminobutyric acid (GABA signaling activation in Arabidopsis and maize stigmas to provide the signals and materials required for pollen tube tip growth. In particular, the "guilt by association" computational pipeline and the genome-scale enzyme correlation network models (GECN developed in this study was initiated with experimental "omics" data, followed by data analysis and data integration to determine correlations, and could provide a new platform to assist inachieving a deeper understanding of the co-regulation and inter

Control of Cell Wall Extensibility during Pollen Tube Growth

OpenAIRE

Hepler, Peter K.; Rounds, Caleb M.; Winship, Lawrence J.

2013-01-01

Tip-growing pollen tubes achieve rapid elongation while maintaining cell wall integrity by balancing local expansion, controlled by local changes in wall viscosity, against exocytosis, influenced by the activity of the actin cytoskeleton, cellular energetics, and calcium and proton physiology.

Molecular and cellular characterization of the tomato pollen profilin, LePro1.

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Long-Xi Yu

Full Text Available Profilin is an actin-binding protein involved in the dynamic turnover and restructuring of the actin cytoskeleton in all eukaryotic cells. We previously cloned a profilin gene, designated as LePro1 from tomato pollen. To understand its biological role, in the present study, we investigated the temporal and spatial expression of LePro1 during pollen development and found that the transcript was only detected at late stages during microsporogenesis and pollen maturation. Using antisense RNA, we successfully knocked down the expression of LePro1 in tomato plants using stable transformation, and obtained two antisense lines, A2 and A3 showing significant down-regulation of LePro1 in pollen resulting in poor pollen germination and abnormal pollen tube growth. A disorganized F-actin distribution was observed in the antisense pollen. Down-regulation of LePro1 also appeared to affect hydration of pollen deposited on the stigma and arrested pollen tube elongation in the style, thereby affecting fertilization. Our results suggest that LePro1 in conjunction with perhaps other cytoskeletal proteins, plays a regulatory role in the proper organization of F-actin in tomato pollen tubes through promoting actin assembly. Down-regulation of LePro1 leads to interruption of actin assembly and disorganization of the actin cytoskeleton thus arresting pollen tube growth. Based on the present and previous studies, it is likely that a single transcript of profilin gives rise to multiple forms displaying multifunctionality in tomato pollen.

Effect of smoke derivatives on in vitro pollen germination and pollen tube elongation of species from different plant families

Czech Academy of Sciences Publication Activity Database

Kumari, A.; Papenfus, H. B.; Kulkarni, M. G.; Pošta, Martin; van Staden, J.

2015-01-01

Roč. 17, č. 4 (2015), s. 825-830 ISSN 1435-8603 Institutional support: RVO:61388963 Keywords : karrikinolide * pollen germination * pollen tube growth * smoke-water * trimethylbutenolide Subject RIV: CC - Organic Chemistry Impact factor: 2.216, year: 2015

Maize EMBRYO SAC family peptides interact differentially with pollen tubes and fungal cells.

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Woriedh, Mayada; Merkl, Rainer; Dresselhaus, Thomas

2015-08-01

EMBRYO SAC1-4 (ES1-4) peptides belong to the defensin subgroup of cysteine-rich peptides known to mediate pollen tube burst in Zea mays (maize). ES1-4 are reported here to also be capable of inhibiting germination and growth of the maize fungal pathogens Fusarium graminearum and Ustilago maydis at higher concentrations. Dividing the peptides into smaller pieces showed that a 15-amino-acid peptide located in a highly variable loop region lacking similarity to other defensins or defensin-like peptides binds to maize pollen tube surfaces, causing swelling prior to burst. This peptide fragment and a second conserved neighbouring fragment showed suppression of fungal germination and growth. The two peptides caused swelling of fungal cells, production of reactive oxygen species, and finally the formation of big vacuoles prior to burst at high peptide concentration. Furthermore, peptide fragments were found to bind differently to fungal cells. In necrotrophic F. graminearum, a peptide fragment named ES-d bound only at cell surfaces whereas the peptide ES-c bound at cell surfaces and also accumulated inside cells. Conversely, in biotrophic U. maydis, both peptide fragments accumulated inside cells, but, if applied at higher concentration, ES-c but not ES-d accumulated mainly in vacuoles. Mapping of peptide interaction sites identified amino acids differing in pollen tube burst and fungal response reactions. In summary, these findings indicate that residues targeting pollen tube burst in maize are specific to the ES family, while residues targeting fungal growth are conserved within defensins and defensin-like peptides. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Using maize as a model to study pollen tube growth and guidance, cross-incompatibility and sperm delivery in grasses.

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Dresselhaus, Thomas; Lausser, Andreas; Márton, Mihaela L

2011-09-01

In contrast to animals and lower plants such as mosses and ferns, sperm cells of flowering plants (angiosperms) are immobile and require transportation to the female gametes via the vegetative pollen tube cell to achieve double fertilization. The path of the pollen tube towards the female gametophyte (embryo sac) has been intensively studied in many intra- and interspecific crossing experiments with the aim of increasing the gene pool of crop plants for greater yield, improved biotic and abiotic stress resistance, and for introducing new agronomic traits. Many attempts to hybridize different species or genotypes failed due to the difficulty for the pollen tubes in reaching the female gametophyte. Detailed studies showed that these processes are controlled by various self-incompatible (intraspecific) and cross-incompatible (interspecific) hybridization mechanisms. Understanding the molecular mechanisms of crossing barriers is therefore of great interest in plant reproduction, evolution and breeding research. In particular, pre-zygotic hybridization barriers related to pollen tube germination, growth, guidance and sperm delivery, which are considered the major hybridization controls in nature and thus also contribute to species isolation and speciation, have been intensively investigated. Despite this general interest, surprisingly little is known about these processes in the most important agronomic plant family, the Gramineae, Poaceae or grasses. Small polymorphic proteins and their receptors, degradation of sterility locus proteins and general compounds such as calcium, γ-aminobutyric acid or nitric oxide have been shown to be involved in progamic pollen germination, adhesion, tube growth and guidance, as well as sperm release. Most advances have been made in the Brassicaceae, Papaveraceae, Linderniaceae and Solanaceae families including their well-understood self-incompatibility (SI) systems. Grass species evolved similar mechanisms to control the penetration

Plant Reproduction and the Pollen Tube Journey--How the Females Lure the Males

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Lorbiecke, Rene

2012-01-01

The growth of pollen tubes is one of the most characteristic events in angiosperm reproduction. This article describes an activity for visualizing the journey and guidance of pollen tubes in the reproductive structures of a flowering plant. The activity uses a semi-in vivo system with rapid-cycling "Brassica rapa," also known as Fast Plants.…

Effect of gamma rays doses on pollen germination, polysiphony and pollen tube elongation in Pinus patula Schiede et Deppe

International Nuclear Information System (INIS)

Katiyar, S.R.; Chauhan, Y.S.

1987-01-01

The present study aimed to study the effects of gamma radiation ( 60 Co) on pollen germination and pollen tube elongation in Pinus patula. Pollen germination and pollen tube elongation are stimulated by low doses of radiation. Although higher doses of radiation inhibit the germination of pollen, pollen tube elongation remains unaffected. Thus in Pinus patula pollen tube elongation is less radiosensitive than pollen germination. Compared to control pollen, irradiated pollen produced more number of long pollen tubes. Therefore pollen tube size can be improved using low doses of radiation. (author). 15 refs., 5 figs., 2 tables

Propidium iodide competes with Ca(2+) to label pectin in pollen tubes and Arabidopsis root hairs.

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Rounds, Caleb M; Lubeck, Eric; Hepler, Peter K; Winship, Lawrence J

2011-09-01

We have used propidium iodide (PI) to investigate the dynamic properties of the primary cell wall at the apex of Arabidopsis (Arabidopsis thaliana) root hairs and pollen tubes and in lily (Lilium formosanum) pollen tubes. Our results show that in root hairs, as in pollen tubes, oscillatory peaks in PI fluorescence precede growth rate oscillations. Pectin forms the primary component of the cell wall at the tip of both root hairs and pollen tubes. Given the electronic structure of PI, we investigated whether PI binds to pectins in a manner analogous to Ca(2+) binding. We first show that Ca(2+) is able to abrogate PI growth inhibition in a dose-dependent manner. PI fluorescence itself also relies directly on the amount of Ca(2+) in the growth solution. Exogenous pectin methyl esterase treatment of pollen tubes, which demethoxylates pectins, freeing more Ca(2+)-binding sites, leads to a dramatic increase in PI fluorescence. Treatment with pectinase leads to a corresponding decrease in fluorescence. These results are consistent with the hypothesis that PI binds to demethoxylated pectins. Unlike other pectin stains, PI at low yet useful concentration is vital and specifically does not alter the tip-focused Ca(2+) gradient or growth oscillations. These data suggest that pectin secretion at the apex of tip-growing plant cells plays a critical role in regulating growth, and PI represents an excellent tool for examining the role of pectin and of Ca(2+) in tip growth.

Cotton transformation via pollen tube pathway.

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Wang, Min; Zhang, Baohong; Wang, Qinglian

2013-01-01

Although many gene transfer methods have been employed for successfully obtaining transgenic cotton, the major constraint in cotton improvement is the limitation of genotype because the majority of transgenic methods require plant regeneration from a single transformed cell which is limited by cotton tissue culture. Comparing with other plant species, it is difficult to induce plant regeneration from cotton; currently, only a limited number of cotton cultivars can be cultured for obtaining regenerated plants. Thus, development of a simple and genotype-independent genetic transformation method is particularly important for cotton community. In this chapter, we present a simple, cost-efficient, and genotype-independent cotton transformation method-pollen tube pathway-mediated transformation. This method uses pollen tube pathway to deliver transgene into cotton embryo sacs and then insert foreign genes into cotton genome. There are three major steps for pollen tube pathway-mediated genetic transformation, which include injection of -foreign genes into pollen tube, integration of foreign genes into plant genome, and selection of transgenic plants.

Expression of an isoflavone reductase-like gene enhanced by pollen tube growth in pistils of Solanum tuberosum.

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van Eldik, G J; Ruiter, R K; Colla, P H; van Herpen, M M; Schrauwen, J A; Wullems, G J

1997-03-01

Successful sexual reproduction relies on gene products delivered by the pistil to create an environment suitable for pollen tube growth. These compounds are either produced before pollination or formed during the interactions between pistil and pollen tubes. Here we describe the pollination-enhanced expression of the cp100 gene in pistils of Solanum tuberosum. Temporal analysis of gene expression revealed an enhanced expression already one hour after pollination and lasts more than 72 h. Increase in expression also occurred after touching the stigma and was not restricted to the site of touch but spread into the style. The predicted CP100 protein shows similarity to leguminous isoflavone reductases (IFRs), but belongs to a family of IFR-like NAD(P)H-dependent oxidoreductases present in various plant species.

Comparative proteomic analysis reveals a dynamic pollen plasma membrane protein map and the membrane landscape of receptor-like kinases and transporters important for pollen tube growth and interaction with pistils in rice.

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Yang, Ning; Wang, Tai

2017-01-05

The coordination of pollen tube (PT) growth, guidance and timely growth arrest and rupture mediated by PT-pistil interaction is crucial for the PT to transport sperm cells into ovules for double fertilization. The plasma membrane (PM) represents an important interface for cell-cell interaction, and PM proteins of PTs are pioneers for mediating PT integrity and interaction with pistils. Thus, understanding the mechanisms underlying these events is important for proteomics. Using the efficient aqueous polymer two-phase system and alkali buffer treatment, we prepared high-purity PM from mature and germinated pollen of rice. We used iTRAQ quantitative proteomic methods and identified 1,121 PM-related proteins (PMrPs) (matched to 899 loci); 192 showed differential expression in the two pollen cell types, 119 increased and 73 decreased in abundance during germination. The PMrP and differentially expressed PMrP sets all showed a functional skew toward signal transduction, transporters, wall remodeling/metabolism and membrane trafficking. Their genomic loci had strong chromosome bias. We found 37 receptor-like kinases (RLKs) from 8 kinase subfamilies and 209 transporters involved in flux of diversified ions and metabolites. In combination with the rice pollen transcriptome data, we revealed that in general, the protein expression of these PMrPs disagreed with their mRNA expression, with inconsistent mRNA expression for 74% of differentially expressed PMrPs. This study identified genome-wide pollen PMrPs, and provided insights into the membrane profile of receptor-like kinases and transporters important for pollen tube growth and interaction with pistils. These pollen PMrPs and their mRNAs showed discordant expression. This work provides resource and knowledge to further dissect mechanisms by which pollen or the PT controls PMrP abundance and monitors interactions and ion and metabolite exchanges with female cells in rice.

Knockin' on pollen's door: live cell imaging of early polarization events in germinating Arabidopsis pollen

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Vogler, Frank; Konrad, Sebastian S. A.; Sprunck, Stefanie

2015-01-01

Pollen tubes are an excellent system for studying the cellular dynamics and complex signaling pathways that coordinate polarized tip growth. Although several signaling mechanisms acting in the tip-growing pollen tube have been described, our knowledge on the subcellular and molecular events during pollen germination and growth site selection at the pollen plasma membrane is rather scarce. To simultaneously track germinating pollen from up to 12 genetically different plants we developed an inexpensive and easy mounting technique, suitable for every standard microscope setup. We performed high magnification live-cell imaging during Arabidopsis pollen activation, germination, and the establishment of pollen tube tip growth by using fluorescent marker lines labeling either the pollen cytoplasm, vesicles, the actin cytoskeleton or the sperm cell nuclei and membranes. Our studies revealed distinctive vesicle and F-actin polarization during pollen activation and characteristic growth kinetics during pollen germination and pollen tube formation. Initially, the germinating Arabidopsis pollen tube grows slowly and forms a uniform roundish bulge, followed by a transition phase with vesicles heavily accumulating at the growth site before switching to rapid tip growth. Furthermore, we found the two sperm cells to be transported into the pollen tube after the phase of rapid tip growth has been initiated. The method presented here is suitable to quantitatively study subcellular events during Arabidopsis pollen germination and growth, and for the detailed analysis of pollen mutants with respect to pollen polarization, bulging, or growth site selection at the pollen plasma membrane. PMID:25954283

The C-terminal hypervariable domain targets Aradopsis ROP9 to the invaginated pollen tube plasma membrane

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Rop9 is a small GTPase of the Type II class, whereas the often studied type I Rops play roles during pollen tube growth. In pollen, Rop9 is located at the invaginated plasma membrane that surrounds the sperm cells, whereas type I Rops are located at the apical membrane of the pollen tube. The C-ter...

Asymmetric localization of Arabidopsis SYP124 syntaxin at the pollen tube apical and sub-apical zones is involved in tip growth

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Silva Pedro

2010-08-01

Full Text Available Abstract Background The continuous polarized vesicle secretion in pollen tubes is essential for tip growth but the location of endo- and exocytic sub-domains remains however controversial. In this report we aimed to show that Arabidopsis thaliana syntaxins are involved in this process and contribute to spatially define exocytosis and membrane recycling. Results Using GFP-fusion constructs, we imaged the distribution of pollen-specific (AtSYP124 and non-pollen syntaxins (AtSYP121 and AtSYP122 in transiently transformed Nicotiana tabacum pollen tubes. All three proteins associate with the plasma membrane and with apical vesicles indicating a conserved action mechanism for all SYPs. However, the GFP tagged SYP124 showed a specific distribution with a higher labelling at the plasma membrane flanks, 10-25 μm behind the apex. This distribution is affected by Ca2+ fluxes as revealed by treatment with Gd3+ (an inhibitor of extracellular Ca2+ influx and TMB-8 (an inhibitor of intracellular Ca2+ release. Both inhibitors decreased growth rate but the distribution of SYP124 at the plasma membrane was more strongly affected by Gd3+. Competition with a related dominant negative mutant affected the specific distribution of SYP124 but not tip growth. In contrast, co-expression of the phosphatidylinositol-4-monophosphate 5-kinase 4 (PIP5K4 or of the small GTPase Rab11 perturbed polarity and the normal distribution of GFP-SYP but did not inhibit the accumulation in vesicles or at the plasma membrane. Conclusions The results presented suggest that in normal growing pollen tubes, a net exocytic flow occurs in the flanks of the tube apex mediated by SYP124. The specific distribution of SYP124 at the plasma membrane is affected by changes in Ca2+ levels in agreement with the importance of this ion for exocytosis. Apical growth and the specific localization of SYP124 were affected by regulators of membrane secretion (Ca2+, PIP5K4 and Rab11 but competition with a

Peptide signalling during the pollen tube journey and double fertilization.

Science.gov (United States)

Qu, Li-Jia; Li, Ling; Lan, Zijun; Dresselhaus, Thomas

2015-08-01

Flowering seed plants (angiosperms) have evolved unique ways to protect their gametes from pathogen attack and from drying out. The female gametes (egg and central cell) are deeply embedded in the maternal tissues of the ovule inside the ovary, while the male gametes (sperm cells) are enclosed in the vegetative pollen tube cell. After germination of the pollen tube at the surface of papilla cells of the stigma the two immobile sperm cells are transported deep inside the sporophytic maternal tissues to be released inside the ovule for double fertilization. Angiosperms have evolved a number of hurdles along the pollen tube journey to prevent inbreeding and fertilization by alien sperm cells, and to maximize reproductive success. These pre-zygotic hybridization barriers require intensive communication between the male and female reproductive cells and the necessity to distinguish self from non-self interaction partners. General molecules such as nitric oxide (NO) or gamma-aminobutyric acid (GABA) therefore appear to play only a minor role in these species-specific communication events. The past 20 years have shown that highly polymorphic peptides play a leading role in all communication steps along the pollen tube pathway and fertilization. Here we review our current understanding of the role of peptides during reproduction with a focus on peptide signalling during self-incompatibility, pollen tube growth and guidance as well as sperm reception and gamete activation. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Dynamic 1-aminocyclopropane-1-carboxylate-synthase and -oxidase transcript accumulation patterns during pollen tube growth in tobacco styles.

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Weterings, Koen; Pezzotti, Mario; Cornelissen, Marc; Mariani, Celestina

2002-11-01

In flowering plants, pollination of the stigma sets off a cascade of responses in the distal flower organs. Ethylene and its biosynthetic precursor 1-aminocyclopropane-1-carboxylate (ACC) play an important role in regulating these responses. Because exogenous application of ethylene or ACC does not invoke the full postpollination syndrome, the pollination signal probably consists of a more complex set of stimuli. We set out to study how and when the pollination signal moves through the style of tobacco (Nicotiana tabacum) by analyzing the expression patterns of pistil-expressed ACC-synthase and -oxidase genes. Results from this analysis showed that pollination induces high ACC-oxidase transcript levels in all cells of the transmitting tissue. ACC-synthase mRNA accumulated only in a subset of transmitting tract cells and to lower levels as compared with ACC-oxidase. More significantly, we found that although ACC-oxidase transcripts accumulate to uniform high levels, the ACC-synthase transcripts accumulate in a wave-like pattern in which the peak coincides with the front of the ingrowing pollen tube tips. This wave of ACC-synthase expression can also be induced by incongruous pollination and (partially) by wounding. This indicates that wounding-like features of pollen tube invasion might be part of the stimuli evoking the postpollination response and that these stimuli are interpreted differently by the regulatory mechanisms of the ACC-synthase and -oxidase genes.

The effect of intracellular calcium level regulators on the synthesis of pollen tube callose in Oenothera biennis L.

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Elżbieta Bednarska

2014-01-01

Full Text Available It is shown that callose synthesis in the Oenothera biennis pollen tube is regulated by the endogenous Ca2+ level. Calcium antagonists reduced the amount of callose in the wall above the tip of the pollen tube (Verapamil - calcium channels blocker and at the tube tip after stopping tube growth (La3+ - a Ca2+ substitute. Ruthenium red and ionophore A 23187, which raise the Ca 21 level in the cytoplasm, induced callose synthesis at the tip of pollen tube.

The Juxtamembrane and carboxy-terminal domains of Arabidopsis PRK2 are critical for ROP-induced growth in pollen tubes

Science.gov (United States)

Polarized growth of pollen tubes is a critical step for successful reproduction in angiosperms and is controlled by ROP GTPases. Spatiotemporal activation of ROP (Rho GTPases of plants) necessitates a complex and sophisticated regulatory system, in which guanine nucleotide exchange factors (RopGEFs)...

[Does a lateral gradient of membrane potential on the plasma membrane of growing pollen tube of germinating pollen grain exist?].

Science.gov (United States)

Andreev, I M

2011-01-01

The data presented in the article by Breigina et al. (2009) "Changes in the membrane potential during pollen grain germination and pollen tube growth" (Tsitologiya. 51 (10): 815-823) and concerning the measurement of electric membrane potential (Delta Psi) on the plasma membrane of growing pollen tube of germinating pollen grain with the use of fluorescent potential-sensitive dye, di-4-ANEPPS, were critically analyzed in order to clarify whether a lateral gradient of Delta Psi on this membrane indeed exists. This analysis showed that the main conclusion of the authors of the above article on the existence of polar distribution of Delta Psi along the pollen tube plasma membrane is not in accordance with a number of known peculiarities of di-4-ANEPPS behavior in biological membranes and requires a significant revision. The findings in question reported by the authors, in my opinion, might be interpreted as evidence for the presence on the plasma membrane of growing pollen tube not only the membrane potential Delta Psi but also lateral gradient of so called intra-membrane dipole potential. Based on the comments made, another interpretation of the experimental results described by Breigina et al. has been offered. In addition, some drawbacks in the methodology used by the authors for measurement of Delta Psi with other fluorescent potential-sensitive dye, DiBAC3(3), are also shortly considered.

[The development of pollen grains and formation of pollen tubes in higher plants : I. Quantitative measurements of the DNA-content of generative and vegetative nuclei in the pollen grain and pollen tube of Petunia hybrida mutants].

Science.gov (United States)

Hesemann, C U

1971-01-01

The DNA-content of generative and vegetative nuclei in mature pollen grains of four Petunia hybrida mutants was determined by cytophotometry. In addition the DNA-content of generative and vegetative nuclei in the pollen tube of two of these four mutants (virescens-2 n and ustulata-2 n) was cytophotometrically measured.The DNA-values found in the generative nuclei indicate that the DNA-replication continues in the mature pollen grain and comes to an end only after the migration of the nuclei into the pollen tube. These data are in disagreement with the results of DNA-measurements described for a limited number of other species which all show completion of DNA-synthesis during the maturation stage of the pollen grains.The vegetative nuclei of the four Petunia mutants studied show significant differences in the onset of the degenerative phase. Extreme variation is manifested in the ustulata-2 n mutant in which the degeneration of nuclei may reach the final stage in the maturing pollen grain. However in this mutant vegetative nuclei with an unaltered DNA-content may also be demonstrated in the pollen tube. Some of the vegetative nuclei in the pollen tube of ustulata-2 n exhibit an increased amount of DNA which could be the result of differential DNA-replication in the vegetative nuclei. The decrease of the DNA-content in a certain fraction of the vegetative nuclei in the maturing pollen grain does not agree with observations made in other species by several authors who report DNA constancy until the pollen grain is fully mature.The data obtained from the analysis of the four Petunia hybrida mutants point to an important role of the vegetative nucleus in the development of the pollen tube. The Petunia hybrida mutants may be regarded as especially favourable material for investigations concerning the function of the vegetative cell in the development of the pollen grain and pollen tube.

Effect of dose rate and exposure time on the stimulation effect of tube growth of Pinus sylvestris pollen

International Nuclear Information System (INIS)

Zelles, L.; Fendrik, I.; Technische Univ. Hannover

1975-01-01

The stimulating effect of ionizing radiation in respect to dose rate and exposure time was studied using the tube growth of Pinus silvestris pollen. Stimulation was registered with a small dose (50 rad) supplied at low dose rates (0.5; 1.0; 3.0 and 5.0 rad/sec) and with higher doses (300; 800 and 1,400 rad) supplied at higher dose rates (10; 40 and 50 rad/sec). This suggests that only the exposure time is of importance for radiation-induced stimulation provided that the exposure time does not exceed 100 sec. (orig.) [de

De Novo Transcriptome Sequencing of Olea europaea L. to Identify Genes Involved in the Development of the Pollen Tube.

Science.gov (United States)

Iaria, Domenico; Chiappetta, Adriana; Muzzalupo, Innocenzo

2016-01-01

In olive (Olea europaea L.), the processes controlling self-incompatibility are still unclear and the molecular basis underlying this process are still not fully characterized. In order to determine compatibility relationships, using next-generation sequencing techniques and a de novo transcriptome assembly strategy, we show that pollen tubes from different olive plants, grown in vitro in a medium containing its own pistil and in combination pollen/pistil from self-sterile and self-fertile cultivars, have a distinct gene expression profile and many of the differentially expressed sequences between the samples fall within gene families involved in the development of the pollen tube, such as lipase, carboxylesterase, pectinesterase, pectin methylesterase, and callose synthase. Moreover, different genes involved in signal transduction, transcription, and growth are overrepresented. The analysis also allowed us to identify members in actin and actin depolymerization factor and fibrin gene family and member of the Ca(2+) binding gene family related to the development and polarization of pollen apical tip. The whole transcriptomic analysis, through the identification of the differentially expressed transcripts set and an extended functional annotation analysis, will lead to a better understanding of the mechanisms of pollen germination and pollen tube growth in the olive.

Characterisation of detergent-insoluble membranes in pollen tubes of Nicotiana tabacum (L.

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Alessandra Moscatelli

2015-02-01

Full Text Available Pollen tubes are the vehicle for sperm cell delivery to the embryo sac during fertilisation of Angiosperms. They provide an intriguing model for unravelling mechanisms of growing to extremes. The asymmetric distribution of lipids and proteins in the pollen tube plasma membrane modulates ion fluxes and actin dynamics and is maintained by a delicate equilibrium between exocytosis and endocytosis. The structural constraints regulating polarised secretion and asymmetric protein distribution on the plasma membrane are mostly unknown. To address this problem, we investigated whether ordered membrane microdomains, namely membrane rafts, might contribute to sperm cell delivery. Detergent insoluble membranes, rich in sterols and sphingolipids, were isolated from tobacco pollen tubes. MALDI TOF/MS analysis revealed that actin, prohibitins and proteins involved in methylation reactions and in phosphoinositide pattern regulation are specifically present in pollen tube detergent insoluble membranes. Tubulins, voltage-dependent anion channels and proteins involved in membrane trafficking and signalling were also present. This paper reports the first evidence of membrane rafts in Angiosperm pollen tubes, opening new perspectives on the coordination of signal transduction, cytoskeleton dynamics and polarised secretion.

Effects on cuytoskeleton system in pollen tube of pinus thunbergii induced by ion beam implantation

International Nuclear Information System (INIS)

Huang Qunce; Liang Qiuxia; Li Guopin

2008-01-01

The damage of the cytoskeleton system in the pollen and the pollen tube of Pinus thunbergii induced by ion beam implantation were researched. The results showed that the disorganization of the micro-tubules in the pollen tube was produced by N + implantation. The abnormal states of the pollen tube in morphology were very correlative with the abnormality of the cytoskeleton system. N + implantation was responsible for morphological abnormalities in the pollen tubes. There was a distinct correlation between the damage effects and the ion implantation dose. The add of dose caused more obvious damage effects. Furthermore, the state of the cytoskeleton system in the pollen tube was influenced by the ion implantation. The impact grade depended also on the ion implantation dose. (authors)

Developmental evolution of flowering plant pollen tube cell walls: callose synthase (CalS gene expression patterns

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Abercrombie Jason M

2011-07-01

Full Text Available Abstract Background A number of innovations underlie the origin of rapid reproductive cycles in angiosperms. A critical early step involved the modification of an ancestrally short and slow-growing pollen tube for faster and longer distance transport of sperm to egg. Associated with this shift are the predominantly callose (1,3-β-glucan walls and septae (callose plugs of angiosperm pollen tubes. Callose synthesis is mediated by callose synthase (CalS. Of 12 CalS gene family members in Arabidopsis, only one (CalS5 has been directly linked to pollen tube callose. CalS5 orthologues are present in several monocot and eudicot genomes, but little is known about the evolutionary origin of CalS5 or what its ancestral function may have been. Results We investigated expression of CalS in pollen and pollen tubes of selected non-flowering seed plants (gymnosperms and angiosperms within lineages that diverged below the monocot/eudicot node. First, we determined the nearly full length coding sequence of a CalS5 orthologue from Cabomba caroliniana (CcCalS5 (Nymphaeales. Semi-quantitative RT-PCR demonstrated low CcCalS5 expression within several vegetative tissues, but strong expression in mature pollen. CalS transcripts were detected in pollen tubes of several species within Nymphaeales and Austrobaileyales, and comparative analyses with a phylogenetically diverse group of sequenced genomes indicated homology to CalS5. We also report in silico evidence of a putative CalS5 orthologue from Amborella. Among gymnosperms, CalS5 transcripts were recovered from germinating pollen of Gnetum and Ginkgo, but a novel CalS paralog was instead amplified from germinating pollen of Pinus taeda. Conclusion The finding that CalS5 is the predominant callose synthase in pollen tubes of both early-diverging and model system angiosperms is an indicator of the homology of their novel callosic pollen tube walls and callose plugs. The data suggest that CalS5 had transient expression

Knockin’ on pollen’s door: live cell imaging of early polarization events in germinating Arabidopsis pollen

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Frank eVogler

2015-04-01

Full Text Available Pollen tubes are an excellent system for studying the cellular dynamics and complex signaling pathways that coordinate polarized tip growth. Although several signaling mechanisms acting in the tip-growing pollen tube have been described, our knowledge on the subcellular and molecular events during pollen germination and growth site selection at the pollen plasma membrane is rather scarce. To simultaneously track germinating pollen from up to 12 genetically different plants we developed an inexpensive and easy mounting technique, suitable for every standard microscope setup. We performed high magnification live-cell imaging during Arabidopsis pollen activation, germination, and the establishment of pollen tube tip growth by using fluorescent marker lines labeling either the pollen cytoplasm, vesicles, the actin cytoskeleton or the sperm cell nuclei and membranes. Our studies revealed distinctive vesicle and F-actin polarization during pollen activation and characteristic growth kinetics during pollen germination and pollen tube formation. Initially, the germinating Arabidopsis pollen tube grows slowly and forms a uniform roundish bulge, followed by a transition phase with vesicles heavily accumulating at the growth site before switching to rapid tip growth. Furthermore, we found the two sperm cells to be transported into the pollen tube after the phase of rapid tip growth has been initiated. The method presented here is suitable to quantitatively study subcellular events during Arabidopsis pollen germination and growth, and for the detailed analysis of pollen mutants with respect to pollen polarization, bulging, or growth site selection at the pollen plasma membrane.

Ultrastructural features of Mimulus aurantiacus (Scrophulariaceae) pollen tubes in vivo

OpenAIRE

Ekici,Nuran; Dane,Feruzan; Olgun,Göksel

2009-01-01

The aim of this study is to give information on ultrastructure of in vivo pollen tubes of Mimulus aurantiacus which were collected from the Botanical Garden of the University of California at Berkeley. Materials were prepared according to electron microscopy methods and examined under Zeiss electron microscope. Four zones were examined in the pollen tubes of Mimulus aurantiacus. APICAL ZONE: Mitochondria, smooth endoplasmic reticulum, rough endoplasmic reticulum, dictyosomes and secretory ves...

Power spectrum, growth velocities and cross-correlations of longitudinal and transverse oscillations of individual Nicotiana tabacum pollen tube.

Science.gov (United States)

Haduch-Sendecka, Aleksandra; Pietruszka, Mariusz; Zajdel, Paweł

2014-08-01

We report on our results concerning growth rate and oscillation modes of the individual pollen tube apex. The observed volumetric growth and growth rate periodicity in the longitudinal (axial) direction are accompanied by transverse oscillations with similar frequencies but higher energies than the axial modes. Examination of the time-domain coherence between oscillations in mutually perpendicular directions revealed minimal energy dissipation in the unperturbed (isotonic) case, opposite to the two remaining cases (hypertonic, hypotonic) with notable correlations. We conjecture that the minimal energy loss is therefore optimal in the natural growth conditions. The longitudinal growth velocity is also found to be the fastest in the unperturbed case. As a result, the isolated system (pollen tube tip) is conserving energy by transforming it from elastic potential energy of extending apical wall to the kinetic energy of periodical motion. The energy dissipation is found to be about 20 % smaller in axial direction than in lateral one, indicating that the main energy consumption is dedicated to the elongation. We further observe that the hypertonic spectrum is shifted towards lower and the hypotonic towards higher frequencies with respect to the isotonic spectrum. In consequence, the turgor pressure inside the growing cell influences monotonically the frequency of both modes of oscillations. The calculated power spectrum seen as a measure of the overall energy efficiency of tip growth under hypertonic, hypotonic and isotonic conditions implies that the biochemistry has been fine tuned to be optimal under normal growth conditions, which is the developmental implication of this work. A simple theoretical extension of the Ortega equation is derived and analysed with respect to its contribution to power spectrum. We show that the plastic term, related to the effective turgor pressure, with maximum contribution at frequency f = 0 is responsible for the steady growth. In turn

Quantitative proteomics of the tobacco pollen tube secretome identifies novel pollen tube guidance proteins important for fertilization

Czech Academy of Sciences Publication Activity Database

Hafidh, Said; Potěšil, D.; Fíla, Jan; Čapková, Věra; Zdráhal, Z.; Honys, David

2016-01-01

Roč. 17, MAY 3 (2016), č. článku 81. ISSN 1465-6906 R&D Projects: GA ČR GA15-22720S; GA ČR(CZ) GA14-32292S; GA ČR(CZ) GA15-16050S; GA MŠk(CZ) LD14109; GA MŠk(CZ) LM2015043; GA MŠk(CZ) ED1.1.00/02.0068; GA MŠk(CZ) LQ1601 Institutional support: RVO:61389030 Keywords : Protein secretion * Pollen tube guidance * Cell-cell signaling Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 11.313, year: 2015

Pollen tube germination in maize does not require transcriptomic changes

Science.gov (United States)

One objective for our group is to better understand the molecular and genetic basis of pollen and pollen tube function, given its critical role in seed production and its importance as a means of gene flow between plant populations. We compared gene expression levels in seedlings...

PCP-B class pollen coat proteins are key regulators of the hydration checkpoint in Arabidopsis thaliana pollen-stigma interactions.

Science.gov (United States)

Wang, Ludi; Clarke, Lisa A; Eason, Russell J; Parker, Christopher C; Qi, Baoxiu; Scott, Rod J; Doughty, James

2017-01-01

The establishment of pollen-pistil compatibility is strictly regulated by factors derived from both male and female reproductive structures. Highly diverse small cysteine-rich proteins (CRPs) have been found to play multiple roles in plant reproduction, including the earliest stages of the pollen-stigma interaction. Secreted CRPs found in the pollen coat of members of the Brassicaceae, the pollen coat proteins (PCPs), are emerging as important signalling molecules that regulate the pollen-stigma interaction. Using a combination of protein characterization, expression and phylogenetic analyses we identified a novel class of Arabidopsis thaliana pollen-borne CRPs, the PCP-Bs (for pollen coat protein B-class) that are related to embryo surrounding factor (ESF1) developmental regulators. Single and multiple PCP-B mutant lines were utilized in bioassays to assess effects on pollen hydration, adhesion and pollen tube growth. Our results revealed that pollen hydration is severely impaired when multiple PCP-Bs are lost from the pollen coat. The hydration defect also resulted in reduced pollen adhesion and delayed pollen tube growth in all mutants studied. These results demonstrate that AtPCP-Bs are key regulators of the hydration 'checkpoint' in establishment of pollen-stigma compatibility. In addition, we propose that interspecies diversity of PCP-Bs may contribute to reproductive barriers in the Brassicaceae. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Turnover of phosphatidic acid through distinct signaling pathways affects multiple aspects of pollen tube growth in tobacco

Czech Academy of Sciences Publication Activity Database

Pleskot, Roman; Pejchar, Přemysl; Bezvoda, R.; Lichtscheidl, I.K.; Wolters-Arts, M.; Marc, J.; Žárský, Viktor; Potocký, Martin

2012-01-01

Roč. 3, č. 54 (2012) ISSN 1664-462X R&D Projects: GA AV ČR IAA601110916; GA MŠk(CZ) LC06034 Institutional research plan: CEZ:AV0Z50380511 Keywords : phosphatidic acid * pollen tube * phospholipase D Subject RIV: EB - Genetics ; Molecular Biology

Design and operation of 140 GHz gyrotron oscillators for power levels up to 1 MW CW

Energy Technology Data Exchange (ETDEWEB)

Jory, H.; Bier, R.; Craig, L.J.; Felch, K.; Ives, L.; Lopez, N.; Spang, S.

1986-12-01

Varian has designed and tested 140 GHz gyrotron oscillators that have generated output powers of 100 kW CW and 200 kW for 1 ms pulses. Upcoming tubes will be designed to operate at power levels of 200 kW CW and ultimately up to 1 MW CW. The important design considerations which are addressed in the higher power tubes include the design of the electron gun, interaction circuit, and output window. These issues will be discussed and the results of the earlier 140 GHz gyrotron work at Varian will be summarized.

Design and operation of 140 GHz gyrotron oscillators for power levels up to 1 MW CW

International Nuclear Information System (INIS)

Jory, H.; Bier, R.; Craig, L.J.; Felch, K.; Ives, L.; Lopez, N.; Spang, S.

1986-12-01

Varian has designed and tested 140 GHz gyrotron oscillators that have generated output powers of 100 kW CW and 200 kW for 1 ms pulses. Upcoming tubes will be designed to operate at power levels of 200 kW CW and ultimately up to 1 MW CW. The important design considerations which are addressed in the higher power tubes include the design of the electron gun, interaction circuit, and output window. These issues will be discussed and the results of the earlier 140 GHz gyrotron work at Varian will be summarized

NADPH oxidase activity in pollen tubes is affected by calcium ions, signaling phospholipids and Rac/Rop GTPases

Czech Academy of Sciences Publication Activity Database

Potocký, Martin; Pejchar, Přemysl; Gutkowska, Malgorzata; Jiménez-Quesada, M. J.; Potocká, Andrea; Alché, J.; Kost, B.; Žárský, Viktor

2012-01-01

Roč. 169, č. 16 (2012), s. 1654-1663 ISSN 0176-1617 R&D Projects: GA ČR GP522/09/P299 Institutional research plan: CEZ:AV0Z50380511 Keywords : Pollen tube * Tip growth * NADPH oxidase Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.699, year: 2012

Loss of the Arabidopsis thaliana P4-ATPases ALA6 and ALA7 Impairs Pollen Fitness and Alters the Pollen Tube Plasma Membrane

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Stephen C McDowell

2015-04-01

Full Text Available Members of the P4 subfamily of P-type ATPases are thought to create and maintain lipid asymmetry in biological membranes by flipping specific lipids between membrane leaflets. In Arabidopsis, 7 of the 12 Aminophospholipid ATPase (ALA family members are expressed in pollen. Here we show that double knockout of ALA6 and ALA7 (ala6/7 results in siliques with a ~2-fold reduction in seed set with a high frequency of empty seed positions near the bottom. Seed set was reduced to near zero when plants were grown under a hot/cold temperature stress. Reciprocal crosses indicate that the ala6/7 reproductive deficiencies are due to a defect related to pollen transmission. In-vitro growth assays provide evidence that that ala6/7 pollen tubes are short and slow, with ~2-fold reductions in both maximal growth rate and overall length relative to wild-type. Outcrosses show that when ala6/7 pollen are in competition with wild-type pollen, they have a near 0% success rate in fertilizing ovules near the bottom of the pistil, consistent with ala6/7 pollen having short and slow growth defects. The ala6/7 phenotypes were rescued by the expression of either an ALA6-YFP or GFP-ALA6 fusion protein, which showed localization to both the plasma membrane and highly-mobile endomembrane structures. A mass spectrometry analysis of mature pollen grains revealed significant differences between ala6/7 and wild-type, both in the relative abundance of lipid classes and in the average number of double bonds present in acyl side chains. A change in the properties of the ala6/7 plasma membrane was also indicated by a ~10-fold reduction of labeling by lipophilic FM-dyes relative to wild-type. Together, these results indicate that ALA6 and ALA7 provide redundant activities that function to directly or indirectly change the distribution and abundance lipids in pollen, and support a model in which ALA6 and ALA7 are critical for pollen fitness under normal and temperature-stress conditions.

Overcoming hybridization barriers by the secretion of the maize pollen tube attractant ZmEA1 from Arabidopsis ovules.

Science.gov (United States)

Márton, Mihaela L; Fastner, Astrid; Uebler, Susanne; Dresselhaus, Thomas

2012-07-10

A major goal of plant reproduction research is to understand and overcome hybridization barriers so that the gene pool of crop plants can be increased and improved upon. After successful pollen germination on a receptive stigma, the nonmotile sperm cells of flowering plants are transported via the pollen tube (PT) to the egg apparatus for the achievement of double fertilization. The PT path is controlled by various hybridization mechanisms probably involving a larger number of species-specific molecular interactions. The egg-apparatus-secreted polymorphic peptides ZmEA1 in maize and LURE1 and LURE2 in Torenia fournieri as well as TcCRP1 in T. concolor were shown to be required for micropylar PT guidance, the last step of the PT journey. We report here that ZmEA1 attracts maize PTs in vitro and arrests their growth at higher concentrations. Furthermore, it binds to the subapical region of maize PT tips in a species-preferential manner. To overcome hybridization barriers at the level of gametophytic PT guidance, we expressed ZmEA1 in Arabidopsis synergid cells. Secreted ZmEA1 enabled Arabidopsis ovules to guide maize PT in vitro in a species-preferential manner to the micropylar opening of the ovule. These results demonstrate that the egg-apparatus-controlled reproductive-isolation barrier of PT guidance can be overcome even between unrelated plant families. Copyright © 2012 Elsevier Ltd. All rights reserved.

Overexpression of Arabidopsis thaliana PTEN caused accumulation of autophagic bodies in pollen tubes by disrupting phosphatidylinositol 3-phosphate dynamics

Science.gov (United States)

Autophagy is a pathway in eukaryotes by which nutrient remobilization occurs through bulk protein and organelle turnover. Autophagy not only aides cells in coping with harsh environments but also plays a key role in many physiological processes that include pollen germination and tube growth. Most a...

Prunus necrotic ringspot virus Early Invasion and Its Effects on Apricot Pollen Grain Performance.

Science.gov (United States)

Amari, Khalid; Burgos, Lorenzo; Pallas, Vicente; Sanchez-Pina, María Amelia

2007-08-01

ABSTRACT The route of infection and the pattern of distribution of Prunus necrotic ringspot virus (PNRSV) in apricot pollen were studied. PNRSV was detected both within and on the surface of infected pollen grains. The virus invaded pollen during its early developmental stages, being detected in pollen mother cells. It was distributed uniformly within the cytoplasm of uni- and bicellular pollen grains and infected the generative cell. In mature pollen grains, characterized by their triangular shape, the virus was located mainly at the apertures, suggesting that PNRSV distribution follows the same pattern as the cellular components required for pollen tube germination and cell wall tube synthesis. PNRSV also was localized inside pollen tubes, especially in the growth zone. In vitro experiments demonstrated that infection with PNRSV decreases the germination percentage of pollen grains by more than half and delays the growth of pollen tubes by approximately 24 h. However, although PNRSV infection affected apricot pollen grain performance during germination, the presence of the virus did not completely prevent fertilization, because the infected apricot pollen tubes, once germinated, were able to reach the apricot embryo sacs, which, in the climatic conditions of southeastern Spain, mature later than in other climates. Thus, infected pollen still could play an important role in the vertical transmission of PNRSV in apricot.

Post-X-irradiation effects on petunia pollen germinating in vitro and in vivo

International Nuclear Information System (INIS)

Gilissen, L.J.W.

1978-01-01

The germination of Petunia hybrida L. pollen grains in germination medium, containing 10% sucrose and 0.01 % H 3 BO 3 , was linearly related to relative humidity (RH): being minimal at 0 % RH and maximal at 100 % RH. The low germination at 0 % RH was completely restored after transfer to 100 % RH. Germination in medium decreased with increasing X-ray exposures between O and 400 kR. This decrease was caused by pollen rupture. No in vitro germination occurred at exposures of 400 kR and more. The radiosensitivity of pollen in vitro was minimal at 80 % RH. Transfer of pollen to the stigma post-X-irradiation resulted in resistance to much higher exposures of irradiation (<750 kR). The differences in radiosensitivity of the pollen germinated in vitro and in vivo are due possibly to the differences in composition of the germination medium and the stigmatic exudate. Pollen tube growth of irradiated pollen after compatible or incompatible pollination at first showed retarded then normal tube growth. A conclusion is that X-irradiation of pollen cannot influence the characteristics of pollen tube growth after compatible or incompatible pollination. (author)

In vitro pollen germination, pollen tube growth and longevity in some ...

African Journals Online (AJOL)

Jane

2011-08-03

Aug 3, 2011 ... Loquat (Eriobotrya japonica Lindl.) is one of the most perspective trees with tasty fruits suitable for commercial production in Iran. However, self-incompatibility of most loquat cultivars makes it necessary to select good pollinizers in breeding and orchard establishment programs. Therefore, studies on pollen ...

Evaluation of the effect of clinostat rotation on pollen germination and tube development as a tool for selection of plants in Space

Science.gov (United States)

De Micco, Veronica; Scala, Michele; Aronne, Giovanna

2006-05-01

The choice of species and cultivar on which rely to sustain Close Loop Environmental Systems is generally approached by analysing the behaviour of plants in presence of stress (sporophytic selection). In this paper, we investigated the possibility to conduct the selection among genotypes in Space through the male gametophytic selection. Thus, we studied the effect of simulated microgravity on pollen germination and tube development of both woody and herbaceous crop species: Prunus armeniaca (apricot), P. dulcis (almond), Malus domestica (apple) and Vicia faba (broad bean). Pollen collected from just bloomed flowers was assessed for viability and incubated on the optimal growing medium in petri dishes both on a uni-axial clinostat and stationary in 1g. Then, pollen was observed under a light microscope to detect percent germination and growth direction. Histochemical analyses were performed to verify the presence and distribution of storage substances. Moreover, specific stainings and epifluorescent microscopy were applied to count nuclei, follow the migration of sperm cells and investigate the presence, size and morphology of callose plugs. Results showed that simulated microgravity affected pollen tube development. The different response showed by the various species indicates that male-gametophytic selection could be useful for the selection of plants in microgravity.

Ultrastructural features of Mimulus aurantiacus (Scrophulariaceae) pollen tubes in vivo.

Science.gov (United States)

Ekici, Nuran; Dane, Feruzan; Olgun, Göksel

2009-03-01

The aim of this study is to give information on ultrastructure of in vivo pollen tubes of Mimulus aurantiacus which were collected from the Botanical Garden of the University of California at Berkeley. Materials were prepared according to electron microscopy methods and examined under Zeiss electron microscope. Four zones were examined in the pollen tubes of Mimulus aurantiacus. Apical zone: Mitochondria, smooth endoplasmic reticulum, rough endoplasmic reticulum, dictyosomes and secretory vesicles were observed. Subapical zone: This area contained abundant rough endoplasmic reticulum and occasionally some smooth endoplasmic reticulum. The polysomes, mitochondria, proplastids that contain starch, small vacuoles and a few lipid bodies were detected. Nuclear zone: Both generative and vegetative cell nuclei lie in this zone. The vegetative cell nucleus was large and long. Rough endoplasmic reticulum, mitochondria, ribosomes, dictyosomes, and amyloplasts that are rich of starch were observed. Vacuolation and plug formation zone: Cytoplasm of the tubes was full of large vacuoles. Few organelles such as mitochondria, dictyosome and rough endoplasmic reticulum were detected along their periphery.

Effects of Alternaria alternata f.sp. lycopersici toxins on pollen

NARCIS (Netherlands)

Bino, R.J.; Franken, J.; Witsenboer, H.M.A.; Hille, J.; Dons, J.J.M.

1988-01-01

Effects of the phytotoxic compounds (AAL-toxins) isolated from cell-free culture filtrates of Alternaria alternata f.sp. lycopersici on in vitro pollen development were studied. AAL-toxins inhibited both germination and tube growth of pollen from several Lycopersicon genotypes. Pollen from

Pollen Biology of Ornamental Ginger (Hedychium spp. J. Koenig)

Science.gov (United States)

An improved in vitro pollen germination assay was developed to assess the viability of stored Hedychium pollen. The effect of polyethylene glycol (PEG) (10, 15, and 20% w/v) on pollen germination and tube growth was evaluated for H. longicornutum and two commercial Hedychium cultivars, ‘Orange Brush...

Identification of a Nicotiana plumbaginifolia plasma membrane H(+)-ATPase gene expressed in the pollen tube.

Science.gov (United States)

Lefebvre, Benoit; Arango, Miguel; Oufattole, Mohammed; Crouzet, Jérôme; Purnelle, Bénédicte; Boutry, Marc

2005-08-01

In Nicotiana plumbaginifolia, plasma membrane H(+)-ATPases (PMAs) are encoded by a gene family of nine members. Here, we report on the characterization of a new isogene, NpPMA5 (belonging to subfamily IV), and the determination of its expression pattern using the beta-glucuronidase (gusA) reporter gene. pNpPMA5-gusA was expressed in cotyledons, in vascular tissues of the stem (mainly in nodal zones), and in the flower and fruit. In the flower, high expression was found in the pollen tube after in vitro or in vivo germination. Northern blotting analysis confirmed that NpPMA5 was expressed in the pollen tube contrary to NpPMA2 (subfamily I) or NpPMA4 (subfamily II), two genes highly expressed in other tissues. The subcellular localization of PM H(+)-ATPase in the pollen tube was analyzed by immunocytodecoration. As expected, this enzyme was localized to the plasma membrane. However, neither the tip nor the base of the pollen tube was labeled, showing an asymmetrical distribution of this enzyme. This observation supports the hypothesis that the PM H(+)-ATPase is involved in creating the pH gradient that is observed along the pollen tube and is implicated in cell elongation. Compared to other plant PM H(+)-ATPases, the C-terminal region of NpPMA5 is shorter by 26 amino acid residues and is modified in the last 6 residues, due to a sequence rearrangement, which was also found in the orthologous gene of Nicotiana glutinosa, a Nicotiana species distant from N. plumbaginifolia and Petunia hybrida and Lycopersicon esculentum, other Solanacae species. This modification alters part of the PM H(+)-ATPase regulatory domain and raises the question whether this isoform is still regulated.

Profiling and functional classification of esterases in olive (Olea europaea) pollen during germination.

Science.gov (United States)

Rejón, Juan D; Zienkiewicz, Agnieszka; Rodríguez-García, María Isabel; Castro, Antonio J

2012-10-01

A pollen grain contains a number of esterases, many of which are released upon contact with the stigma surface. However, the identity and function of most of these esterases remain unknown. In this work, esterases from olive pollen during its germination were identifided and functionally characterized. The esterolytic capacity of olive (Olea europaea) pollen was examined using in vitro and in-gel enzymatic assays with different enzyme substrates. The functional analysis of pollen esterases was achieved by inhibition assays by using specific inhibitors. The cellular localization of esterase activities was performed using histochemical methods. Olive pollen showed high levels of non-specific esterase activity, which remained steady after hydration and germination. Up to 20 esterolytic bands were identified on polyacrylamide gels. All the inhibitors decreased pollen germinability, but only diisopropyl fluorophosphate (DIFP) hampered pollen tube growth. Non-specific esterase activity is localized on the surface of oil bodies (OBs) and small vesicles, in the pollen intine and in the callose layer of the pollen tube wall. Acetylcholinesterase (AChE) activity was mostly observed in the apertures, exine and pollen coat, and attached to the pollen tube wall surface and to small cytoplasmic vesicles. In this work, for the first time a systematic functional characterization of esterase enzymes in pollen from a plant species with wet stigma has been carried out. Olive pollen esterases belong to four different functional groups: carboxylesterases, acetylesterases, AChEs and lipases. The cellular localization of esterase activity indicates that the intine is a putative storage site for esterolytic enzymes in olive pollen. Based on inhibition assays and cellular localization of enzymatic activities, it can be concluded that these enzymes are likely to be involved in pollen germination, and pollen tube growth and penetration of the stigma.

Kanamycin resistance during in vitro development of pollen from transgenic tomato plants

NARCIS (Netherlands)

Bino, R.J.; Hille, J.; Franken, J.

1987-01-01

Effects of kanamycin on pollen germination and tube growth of pollen from non-transformed plants and from transgenic tomato plants containing a chimaeric kanamycin resistance gene were determined. Germination of pollen was not affected by the addition of kanamycin to the medium in both genotypes.

Methods to isolate a large amount of generative cells, sperm cells and vegetative nuclei from tomato pollen for "omics" analysis.

Science.gov (United States)

Lu, Yunlong; Wei, Liqin; Wang, Tai

2015-01-01

The development of sperm cells (SCs) from microspores involves a set of finely regulated molecular and cellular events and the coordination of these events. The mechanisms underlying these events and their interconnections remain a major challenge. Systems analysis of genome-wide molecular networks and functional modules with high-throughput "omics" approaches is crucial for understanding the mechanisms; however, this study is hindered because of the difficulty in isolating a large amount of cells of different types, especially generative cells (GCs), from the pollen. Here, we optimized the conditions of tomato pollen germination and pollen tube growth to allow for long-term growth of pollen tubes in vitro with SCs generated in the tube. Using this culture system, we developed methods for isolating GCs, SCs and vegetative cell nuclei (VN) from just-germinated tomato pollen grains and growing pollen tubes and their purification by Percoll density gradient centrifugation. The purity and viability of isolated GCs and SCs were confirmed by microscopy examination and fluorescein diacetate staining, respectively, and the integrity of VN was confirmed by propidium iodide staining. We could obtain about 1.5 million GCs and 2.0 million SCs each from 180 mg initiated pollen grains, and 10 million VN from 270 mg initiated pollen grains germinated in vitro in each experiment. These methods provide the necessary preconditions for systematic biology studies of SC development and differentiation in higher plants.

An osmotic model of the growing pollen tube.

Directory of Open Access Journals (Sweden)

Adrian E Hill

Full Text Available Pollen tube growth is central to the sexual reproduction of plants and is a longstanding model for cellular tip growth. For rapid tip growth, cell wall deposition and hardening must balance the rate of osmotic water uptake, and this involves the control of turgor pressure. Pressure contributes directly to both the driving force for water entry and tip expansion causing thinning of wall material. Understanding tip growth requires an analysis of the coordination of these processes and their regulation. Here we develop a quantitative physiological model which includes water entry by osmosis, the incorporation of cell wall material and the spreading of that material as a film at the tip. Parameters of the model have been determined from the literature and from measurements, by light, confocal and electron microscopy, together with results from experiments made on dye entry and plasmolysis in Lilium longiflorum. The model yields values of variables such as osmotic and turgor pressure, growth rates and wall thickness. The model and its predictive capacity were tested by comparing programmed simulations with experimental observations following perturbations of the growth medium. The model explains the role of turgor pressure and its observed constancy during oscillations; the stability of wall thickness under different conditions, without which the cell would burst; and some surprising properties such as the need for restricting osmotic permeability to a constant area near the tip, which was experimentally confirmed. To achieve both constancy of pressure and wall thickness under the range of conditions observed in steady-state growth the model reveals the need for a sensor that detects the driving potential for water entry and controls the deposition rate of wall material at the tip.

An Osmotic Model of the Growing Pollen Tube

Science.gov (United States)

Hill, Adrian E.; Shachar-Hill, Bruria; Skepper, Jeremy N.; Powell, Janet; Shachar-Hill, Yair

2012-01-01

Pollen tube growth is central to the sexual reproduction of plants and is a longstanding model for cellular tip growth. For rapid tip growth, cell wall deposition and hardening must balance the rate of osmotic water uptake, and this involves the control of turgor pressure. Pressure contributes directly to both the driving force for water entry and tip expansion causing thinning of wall material. Understanding tip growth requires an analysis of the coordination of these processes and their regulation. Here we develop a quantitative physiological model which includes water entry by osmosis, the incorporation of cell wall material and the spreading of that material as a film at the tip. Parameters of the model have been determined from the literature and from measurements, by light, confocal and electron microscopy, together with results from experiments made on dye entry and plasmolysis in Lilium longiflorum. The model yields values of variables such as osmotic and turgor pressure, growth rates and wall thickness. The model and its predictive capacity were tested by comparing programmed simulations with experimental observations following perturbations of the growth medium. The model explains the role of turgor pressure and its observed constancy during oscillations; the stability of wall thickness under different conditions, without which the cell would burst; and some surprising properties such as the need for restricting osmotic permeability to a constant area near the tip, which was experimentally confirmed. To achieve both constancy of pressure and wall thickness under the range of conditions observed in steady-state growth the model reveals the need for a sensor that detects the driving potential for water entry and controls the deposition rate of wall material at the tip. PMID:22615784

Pd-nanoparticles cause increased toxicity to kiwifruit pollen compared to soluble Pd(II)

International Nuclear Information System (INIS)

Speranza, Anna; Leopold, Kerstin; Maier, Marina; Taddei, Anna Rita; Scoccianti, Valeria

2010-01-01

In the present study, endpoints including in vitro pollen performance (i.e., germination and tube growth) and lethality were used as assessments of nanotoxicity. Pollen was treated with 5-10 nm-sized Pd particles, similar to those released into the environment by catalytic car exhaust converters. Results showed Pd-nanoparticles altered kiwifruit pollen morphology and entered the grains more rapidly and to a greater extent than soluble Pd(II). At particulate Pd concentrations well below those of soluble Pd(II), pollen grains experienced rapid losses in endogenous calcium and pollen plasma membrane damage was induced. This resulted in severe inhibition and subsequent cessation of pollen tube emergence and elongation at particulate Pd concentrations as low as 0.4 mg L -1 . Particulate Pd emissions related to automobile traffic have been increasing and are accumulating in the environment. This could seriously jeopardize in vivo pollen function, with impacts at an ecosystem level. - Nanoparticulate Pd - which resembles emissions from automobile catalysts - affects pollen to a higher extent than soluble Pd.

Pd-nanoparticles cause increased toxicity to kiwifruit pollen compared to soluble Pd(II)

Energy Technology Data Exchange (ETDEWEB)

Speranza, Anna, E-mail: anna.speranza@unibo.i [Dipartimento di Biologia, Universita di Bologna, via Irnerio 42, 40126 Bologna (Italy); Leopold, Kerstin, E-mail: kerstin.leopold@lrz.tu-muenchen.d [Arbeitsgruppe fuer Analytische Chemie, Technische Universitaet Muenchen, Garching (Germany); Maier, Marina, E-mail: marina.maier@ch.tum.d [Arbeitsgruppe fuer Analytische Chemie, Technische Universitaet Muenchen, Garching (Germany); Taddei, Anna Rita, E-mail: artaddei@unitus.i [CIME, Universita della Tuscia, Viterbo (Italy); Scoccianti, Valeria, E-mail: valeria.scoccianti@uniurb.i [Dipartimento di Scienze dell' Uomo, dell' Ambiente e della Natura, Universita di Urbino ' Carlo Bo' , Urbino (Italy)

2010-03-15

In the present study, endpoints including in vitro pollen performance (i.e., germination and tube growth) and lethality were used as assessments of nanotoxicity. Pollen was treated with 5-10 nm-sized Pd particles, similar to those released into the environment by catalytic car exhaust converters. Results showed Pd-nanoparticles altered kiwifruit pollen morphology and entered the grains more rapidly and to a greater extent than soluble Pd(II). At particulate Pd concentrations well below those of soluble Pd(II), pollen grains experienced rapid losses in endogenous calcium and pollen plasma membrane damage was induced. This resulted in severe inhibition and subsequent cessation of pollen tube emergence and elongation at particulate Pd concentrations as low as 0.4 mg L{sup -1}. Particulate Pd emissions related to automobile traffic have been increasing and are accumulating in the environment. This could seriously jeopardize in vivo pollen function, with impacts at an ecosystem level. - Nanoparticulate Pd - which resembles emissions from automobile catalysts - affects pollen to a higher extent than soluble Pd.

Antinuclear human autoantibodies as markers in Nicotiana tabacum pollen tubes

Directory of Open Access Journals (Sweden)

C. Poggialini

2014-01-01

Full Text Available In the present paper we report on the use of antinuclear human autoantibodies as specific markers in Nicotiana tabacum pollen tubes. The antibodies have been tested by fluorescence techniques using a confocal laser scanning microscope. All the antibodies showed specifc labelling pattern and the results, although preliminary in nature, could open new perspectives of research.

Multiple BiP genes of Arabidopsis thaliana are required for male gametogenesis and pollen competitiveness.

Science.gov (United States)

Maruyama, Daisuke; Sugiyama, Tomoyuki; Endo, Toshiya; Nishikawa, Shuh-Ichi

2014-04-01

Immunoglobulin-binding protein (BiP) is a molecular chaperone of the heat shock protein 70 (Hsp70) family. BiP is localized in the endoplasmic reticulum (ER) and plays key roles in protein translocation, protein folding and quality control in the ER. The genomes of flowering plants contain multiple BiP genes. Arabidopsis thaliana has three BiP genes. BIP1 and BIP2 are ubiquitously expressed. BIP3 encodes a less well conserved BiP paralog, and it is expressed only under ER stress conditions in the majority of organs. Here, we report that all BiP genes are expressed and functional in pollen and pollen tubes. Although the bip1 bip2 double mutation does not affect pollen viability, the bip1 bip2 bip3 triple mutation is lethal in pollen. This result indicates that lethality of the bip1 bip2 double mutation is rescued by BiP3 expression. A decrease in the copy number of the ubiquitously expressed BiP genes correlates well with a decrease in pollen tube growth, which leads to reduced fitness of mutant pollen during fertilization. Because an increased protein secretion activity is expected to increase the protein folding demand in the ER, the multiple BiP genes probably cooperate with each other to ensure ER homeostasis in cells with active secretion such as rapidly growing pollen tubes.

NaStEP: A Proteinase Inhibitor Essential to Self-Incompatibility and a Positive Regulator of HT-B Stability in Nicotiana alata Pollen Tubes1[W][OA

Science.gov (United States)

Jiménez-Durán, Karina; McClure, Bruce; García-Campusano, Florencia; Rodríguez-Sotres, Rogelio; Cisneros, Jesús; Busot, Grethel; Cruz-García, Felipe

2013-01-01

In Solanaceae, the self-incompatibility S-RNase and S-locus F-box interactions define self-pollen recognition and rejection in an S-specific manner. This interaction triggers a cascade of events involving other gene products unlinked to the S-locus that are crucial to the self-incompatibility response. To date, two essential pistil-modifier genes, 120K and High Top-Band (HT-B), have been identified in Nicotiana species. However, biochemistry and genetics indicate that additional modifier genes are required. We recently reported a Kunitz-type proteinase inhibitor, named NaStEP (for Nicotiana alata Stigma-Expressed Protein), that is highly expressed in the stigmas of self-incompatible Nicotiana species. Here, we report the proteinase inhibitor activity of NaStEP. NaStEP is taken up by both compatible and incompatible pollen tubes, but its suppression in Nicotiana spp. transgenic plants disrupts S-specific pollen rejection; therefore, NaStEP is a novel pistil-modifier gene. Furthermore, HT-B levels within the pollen tubes are reduced when NaStEP-suppressed pistils are pollinated with either compatible or incompatible pollen. In wild-type self-incompatible N. alata, in contrast, HT-B degradation occurs preferentially in compatible pollinations. Taken together, these data show that the presence of NaStEP is required for the stability of HT-B inside pollen tubes during the rejection response, but the underlying mechanism is currently unknown. PMID:23150644

Methods to isolate a large amount of generative cells, sperm cells and vegetative nuclei from tomato pollen for omics analysis

Directory of Open Access Journals (Sweden)

Yunlong eLu

2015-06-01

Full Text Available The development of sperm cells from microspores involves a set of finely regulated molecular and cellular events and the coordination of these events. The mechanisms underlying these events and their interconnections remain a major challenge. Systems analysis of genome-wide molecular networks and functional modules with high-throughput omics approaches is crucial for understanding the mechanisms; however, this study is hindered because of the difficulty in isolating a large amount of cells of different types, especially generative cells (GCs, from the pollen. Here, we optimized the conditions of tomato pollen germination and pollen tube growth to allow for long-term growth of pollen tubes in vitro with sperm cells (SCs generated in the tube. Using this culture system, we developed methods for isolating GCs, SCs and vegetative-cell nuclei (VN from just-germinated tomato pollen grains and growing pollen tubes and their purification by Percoll density gradient centrifugation. The purity and viability of isolated GCs and SCs were confirmed by microscopy examination and fluorescein diacetate staining, respectively, and the integrity of VN was confirmed by propidium iodide staining. We could obtain about 1.5 million GCs and 2.0 million SCs each from 180 mg initiated pollen grains, and 10 million VN from 270 mg initiated pollen grains germinated in vitro in each experiment. These methods provide the necessary preconditions for systematic biology studies of SC development and differentiation in higher plants.

Does stronger pollen competition improve offspring fitness when pollen load does not vary?

Science.gov (United States)

Pélabon, Christophe; Hennet, Lauriane; Bolstad, Geir H; Albertsen, Elena; Opedal, Øystein H; Ekrem, Runa K; Armbruster, W Scott

2016-03-01

Competition among pollen grains from a single donor is expected to increase the quality of the offspring produced because of the recessive deleterious alleles expressed during pollen-tube growth. However, evidence for such an effect is inconclusive; a large number of studies suffer from confounding variation in pollen competition with variation in pollen load. In this study, we tested the effect of pollen competition on offspring performance independently of pollen-load variation. We compared seed mass and early seedling performance in Dalechampia scandens (Euphorbiaceae) between crosses in which variation in pollen competition was achieved, without variation in pollen load, by manipulating the dispersion of pollen grains on the stigmas. Despite a large sample size (211 crosses on 20 maternal plants), we failed to find an effect of pollen competition on seed characteristics or early seedling performance. Paternal effects were always limited, and pollen competition never reduced the within-father (residual) variance. These results suggest that limited within-donor variation in genetic quality of pollen grains reduces the potential benefits of pollen competition in the study population. The lack of paternal effects on early sporophyte performance further suggests that benefits of pollen competition among pollen from multiple donors should be limited as well, and it raises questions about the significance of pollen competition as a mechanism of sexual selection. © 2016 Botanical Society of America.

Viabilidade do pólen e desenvolvimento do tubo polínico em macieira (Malus spp. Germination of pollen and the development of pollen tubes in apple (Malus spp.

Directory of Open Access Journals (Sweden)

Adriana Cibele de Mesquita Dantas

2005-12-01

Full Text Available No presente trabalho, estudaram-se características associadas à germinação in vitro e ao desenvolvimento in vivo do tubo polínico em seis variedades-copa e de porta-enxertos de macieira como subsídios para o estabelecimento de programas de melhoramento genético. Utilizou-se de pólen de seis cultivares de macieira inoculado em meio de cultura com ágar (10 g.L-1 em água destilada, combinados com concentrações de sacarose (0; 10; 20; 30; 40 e 50% e ácido bórico (0 e 40 mg.L-1. Para o estudo do desenvolvimento do tubo polínico, realizou-se coleta das flores em quatro períodos (6; 12; 24 e 48 horas após as polinizações em M9 x Marubakaido e a autofecundação em M9, sendo os tubos polínicos analisados em coloração de azul de anilina acidificada/carmim acético e em fluorescência. A sacarose, em concentrações entre 15% a 25%, pode ser empregada com sucesso para a germinação in vitro de grãos de pólen da macieira. O ácido bórico não teve efeito positivo para esta característica. Na ausência do ácido bórico e na presença de 15% de sacarose, observaram-se os maiores percentuais de germinação: Fuji (51,1%, Imperatriz (31,7%, M.9 (20,8%, Catarina (19,2%, Gala (13,7% e Marubakaido (6,1%. Quanto ao desenvolvimento do tubo polínico, com 12 horas da polinização, iniciou-se a germinação no pólen, no estigma, no cruzamento M.9 x Marubakaido, e após 24 horas da polinização observou-se 83% de germinação. As técnicas de coloração com azul de anilina acidificada com carmim acético e de visualização em fluorescência foram eficientes na visualização e coloração dos grãos de pólen e do desenvolvimento dos tubos polínicos.In the present work it was studied features associated to the germination of pollen and the development of pollen tubes in six apple varieties as subsidies for the establishment of genetic improvement programs. Pollen grains were inoculated in culture medium with distilled water, agar (10

Transport logistics in pollen tubes.

Science.gov (United States)

Chebli, Youssef; Kroeger, Jens; Geitmann, Anja

2013-07-01

Cellular organelles move within the cellular volume and the effect of the resulting drag forces on the liquid causes bulk movement in the cytosol. The movement of both organelles and cytosol leads to an overall motion pattern called cytoplasmic streaming or cyclosis. This streaming enables the active and passive transport of molecules and organelles between cellular compartments. Furthermore, the fusion and budding of vesicles with and from the plasma membrane (exo/endocytosis) allow for transport of material between the inside and the outside of the cell. In the pollen tube, cytoplasmic streaming and exo/endocytosis are very active and fulfill several different functions. In this review, we focus on the logistics of intracellular motion and transport processes as well as their biophysical underpinnings. We discuss various modeling attempts that have been performed to understand both long-distance shuttling and short-distance targeting of organelles. We show how the combination of mechanical and mathematical modeling with cell biological approaches has contributed to our understanding of intracellular transport logistics.

Status of the development of the EU 170 GHz/1 MW/CW gyrotron

Energy Technology Data Exchange (ETDEWEB)

Pagonakis, Ioannis Gr., E-mail: ioannis.pagonakis@kit.edu [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Albajar, Ferran [The European Joint Undertaking for ITER and The Development of Fusion Energy, Barcelona (Spain); Alberti, Stefano [École Polytechnique Fédérale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), Lausanne (Switzerland); Avramidis, Konstantinos [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Bonicelli, Tullio [The European Joint Undertaking for ITER and The Development of Fusion Energy, Barcelona (Spain); Braunmueller, Falk [École Polytechnique Fédérale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), Lausanne (Switzerland); Bruschi, Alex [Plasma Physics Institute, National Research Council of Italy, Milano (Italy); Chelis, Ioannis [School of Electrical and Computer Engineering, National Technical University of Athens (Greece); Cismondi, Fabio [The European Joint Undertaking for ITER and The Development of Fusion Energy, Barcelona (Spain); Gantenbein, Gerd [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Hermann, Virgile [Thales Electron Devices (TED), Vélizy-Villacoublay (France); Hesch, Klaus [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Hogge, Jean-Philippe [École Polytechnique Fédérale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), Lausanne (Switzerland); Jelonnek, John; Jin, Jianbo; Illy, Stefan [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Ioannidis, Zisis C. [Faculty of Physics, National and Kapodistrian University of Athens (Greece); Kobarg, Thorsten [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); and others

2015-10-15

The progress in the development of the European 170 GHz, 1 MW/CW gyrotron for electron cyclotron heating & current drive (ECH&CD) on ITER is reported. A continuous wave (CW) prototype is being manufactured by Thales Electron Devices (TED), France, while a short-pulse (SP) prototype gyrotron is in parallel under manufacture at Karlsruhe Institute of Technology (KIT), with the purpose of validating the design of the CW industrial prototype components. The fabrication of most of the sub-assemblies of the SP prototype has been completed. In a first step, an existing magnetron injection gun (MIG) available at KIT was used. Despite this non-ideal configuration, the experiments provided a validation of the design, substantiated by an excellent agreement with numerical simulations. The tube, operated without a depressed collector, is able to produce more than 1 MW of output power with efficiency in excess of 30%, as expected, and compatible with the ITER requirements.

The diversity of the pollen tube pathway in plants: towards an increasing control by the sporophyte

Directory of Open Access Journals (Sweden)

Jorge eLora

2016-02-01

Full Text Available Plants, unlike animals, alternate multicellular diploid and haploid generations in their life cycle. While this is widespread all along the plant kingdom, the size and autonomy of the diploid sporophyte and the haploid gametophyte generations vary along evolution. Vascular plants show an evolutionary trend towards a reduction of the gametophyte, reflected both in size and lifespan, together with an increasing dependence from the sporophyte. This has resulted in an overlooking of the importance of the gametophytic phase in the evolution of higher plants. This reliance on the sporophyte is most notorious along the pollen tube journey, where the male gametophytes have to travel a long way inside the sporophyte to reach the female gametophyte. Along evolution, there is a change in the scenery of the pollen tube pathway that favors pollen competition and selection. This trend, towards apparently making complicated what could be simple, appears to be related to an increasing control of the sporophyte over the gametophyte with implications for understanding plant evolution.

In-pile creep strain and failure of CW 316 Ti pressurized tubes

International Nuclear Information System (INIS)

Boutard, J.L.; Maillard, A.; Carteret, Y.; Levy, V.; Meny, L.

1984-06-01

The in-pile creep and failure behavior of CW 316 Ti pressurized tubes irradiated in the same rig at 660-680 0 C and 81.4 dpaF max in Phenix is presented and compared to monitors of the same heat. The in-pile plastic strains are of the same order of what is expected from the monitors and are rather independent of the dose rate in the range 4 to 9 x 10 -3 dpaF/h. Such a behavior supports the assumption that the out-of-pile deformation mechanisms are operative in pile and a certain balance occurs between modification of the microstructure, dynamic hardening and deformation mechanisms due to irradiation. Examinations by fractography and optical micrography, show that the failures are intergranular either in-pile or out-of-pile. In both cases the damage consists in intergranular wedge cracks, and no cavitation can be observed by transmission electron microscopy. Then the in-pile embrittlement which gives lower failure strain and time is to be associated with a decrease of the surface energy of grain-boundaries rather then growth and coalescence of cavities

Design of spherical electron gun for ultra high frequency, CW power inductive output tube

International Nuclear Information System (INIS)

Kaushik, Meenu; Joshi, L. M.

2016-01-01

Inductive Output Tube (IOT) is an amplifier that usually operates in UHF range. It is an electron tube whose basic structure is similar to conventional vacuum devices. This device is widely used in broadcast applications but is now being explored for scientific applications also specifically, particle accelerators and fusion plasma heating purposes. The paper describes the design approach of a spherical gridded electron gun of a 500 MHz, 100 kW CW power IOT. The electron gun structure has been simulated and optimized for operating voltage and current of 40kV and 3.5 A respectively. The electromagnetic analysis of this spherical electron gun has been carried out in CST and TRAK codes.

Design of spherical electron gun for ultra high frequency, CW power inductive output tube

Energy Technology Data Exchange (ETDEWEB)

Kaushik, Meenu, E-mail: mkceeri@gmail.com; Joshi, L. M., E-mail: lmj1953@gmail.com [Microwave Tubes Division, CSIR-Central Electronics Engineering Research Institute (CEERI), Pilani, Rajasthan (India); Academy of Scientific and Innovative Research (AcSIR), New Delhi (India)

2016-03-09

Inductive Output Tube (IOT) is an amplifier that usually operates in UHF range. It is an electron tube whose basic structure is similar to conventional vacuum devices. This device is widely used in broadcast applications but is now being explored for scientific applications also specifically, particle accelerators and fusion plasma heating purposes. The paper describes the design approach of a spherical gridded electron gun of a 500 MHz, 100 kW CW power IOT. The electron gun structure has been simulated and optimized for operating voltage and current of 40kV and 3.5 A respectively. The electromagnetic analysis of this spherical electron gun has been carried out in CST and TRAK codes.

A 700 MHZ, 1 MW CW RF System for a FEL 100mA RF Photoinjector

CERN Document Server

Roybal, William; Reass, William; Rees, Daniel; Tallerico, Paul J; Torrez, Phillip A

2005-01-01

This paper describes a 700 MHz, 1 Megawatt CW, high efficiency klystron RF system utilized for a Free Electron Laser (FEL) high-brightness electron photoinjector (PI). The E2V klystron is mod-anode tube that operates with a beam voltage of 95 kV. This tube, operating with a 65% efficiency, requires ~96 watts of input power to produce in excess of 1 MW of output power. This output drives the 3rd cell of a 2½-cell, p-mode PI cavity through a pair of planar waveguide windows. Coupling is via a ridge-loaded tapered waveguide section and "dog-bone" iris. This paper will present the design of the RF, RF transport, coupling, and monitoring/protection systems that are required to support CW operations of the 100 mA cesiated, semi-porous SiC photoinjector.

Distribution of exogenous DNA in upland cotton by pollen tube pathway

International Nuclear Information System (INIS)

Yang Shuhua; Ge Cailin; Zhu Jing; Wang Zegang; Luo Shishi; Ni Wanchao

2007-01-01

The distribution of exogenous DNA in upland cotton by pollen tube pathway was studied. The results showed that the exogenous DNA could be transported into ovules by dripping and injection. The optimum time for treatment is at 33 h after pollination. The radioactivity in ovules by dripping exogenous DNA was lower than that by injecting. In autoradiogram, the number of sliver grains in the treated ovules was more than that in the controls. (authors)

Pollen extracts and constituent sugars increase growth of a trypanosomatid parasite of bumble bees

Directory of Open Access Journals (Sweden)

Evan C. Palmer-Young

2017-05-01

Full Text Available Phytochemicals produced by plants, including at flowers, function in protection against plant diseases, and have a long history of use against trypanosomatid infection. Floral nectar and pollen, the sole food sources for many species of insect pollinators, contain phytochemicals that have been shown to reduce trypanosomatid infection in bumble and honey bees when fed as isolated compounds. Nectar and pollen, however, consist of phytochemical mixtures, which can have greater antimicrobial activity than do single compounds. This study tested the hypothesis that pollen extracts would inhibit parasite growth. Extracts of six different pollens were tested for direct inhibitory activity against cell cultures of the bumble bee trypanosomatid gut parasite Crithidia bombi. Surprisingly, pollen extracts increased parasite growth rather than inhibiting it. Pollen extracts contained high concentrations of sugars, mainly the monosaccharides glucose and fructose. Experimental manipulations of growth media showed that supplemental monosaccharides (glucose and fructose increased maximum cell density, while a common floral phytochemical (caffeic acid with inhibitory activity against other trypanosomatids had only weak inhibitory effects on Crithidia bombi. These results indicate that, although pollen is essential for bees and other pollinators, pollen may promote growth of intestinal parasites that are uninhibited by pollen phytochemicals and, as a result, can benefit from the nutrients that pollen provides.

Flowering and the Pollen Fertility in Iranian Garlic Clones

Directory of Open Access Journals (Sweden)

A. R. Abbasifar

2015-06-01

Full Text Available Garlic (Allium sativum L. cannot produce seed because it is a sterile plant. For studying bolting and determination of pollen fertility, 68 Iranian garlic clones were gathered from different parts of Iran and evaluated in Research Field of Horticultural Department, Faculty of Agriculture, Bu-Ali Sina University in 2010-2011 and 2011-2012. For determining the pollen fertility, some tests including specific RAPD marker, pollen germination, pollen viability detection using acetocarmine and in vitro culture of ovules and fruits were used. Results showed that 37 of Iranian garlic clones could produce scape and inflorescence. The percentage range of pollen stained with acetocarmine was from 0.5 up to 20 percent showing infertility of pollens. Lack of two markers (OPJ121300 and OPJ121700 and pollen tube growth proved the infertility of garlic clones pollen. Fruits and embryo sac were alive for more than two months, showing their potential for producing seeds following pollination with fertile pollens.

The influence of pollen γ-irradiation of the growth and development of plants

International Nuclear Information System (INIS)

Andrejchenko, S.V.; Grodzinskij, D.M.

1986-01-01

A study was made on the influence of pollen gamma irradiation on induction of phenotypic mutation in F 1 hybrid petunia. Some dose regularities characterizing the rate of growth and development of daughter plants were revealed. It was shown that seed formation and embryogenesis depend directly on the degree of pollen gamma irradiation damage

Temperatures during flower bud development affect pollen germination, self-incompatibility reaction and early fruit development of clementine (Citrus clementina Hort. ex Tan.).

Science.gov (United States)

Distefano, G; Gentile, A; Hedhly, A; La Malfa, S

2018-03-01

One of the key environmental factors affecting plant reproductive systems is temperature. Characterising such effects is especially relevant for some commercially important genera such as Citrus. In this genus, failure of fertilisation results in parthenocarpic fruit development and seedlessness, which is a much-prized character. Here, we characterise the effects of temperature on flower and ovary development, and on pollen-pistil interactions in 'Comune' clementine (Citrus clementina Hort. ex Tan.). We examine flower bud development, in vitro pollen germination and pollen-pistil interaction at different temperatures (15, 20, 25 or 30 °C). These temperatures span the range from 'cold' to 'hot' weather during the flowering season in many citrus-growing regions. Temperature had a strong effect on flower and ovary development, pollen germination, and pollen tube growth kinetics. In particular, parthenocarpic fruit development (indicated by juice vesicle growth) was initiated early if flowers were exposed to warmer temperatures during anthesis. Exposure to different temperatures during flower bud development also alters expression of the self-incompatibility reaction. This affects the point in the pistil at which pollen tube growth is arrested and confirms the role of sub- and supra-optimal temperatures in determining the numbers of pollen tubes reaching the ovary. © 2017 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.

Pollen characteristics and in vitro pollen germination of Cedrus ...

African Journals Online (AJOL)

PRECIOUS

2009-11-02

Nov 2, 2009 ... This study aims to determine the germination characteristics, pollen tube developments, effects of germination media and temperature and incubation durations of the pollens obtained from the four clones (11342, 11344, 11345 and 11351) of Cedrus libani A. Rich. (Lebanon Cedrus) obtained from clonal.

Ecological stoichiometry of the honeybee: Pollen diversity and adequate species composition are needed to mitigate limitations imposed on the growth and development of bees by pollen quality.

Science.gov (United States)

Filipiak, Michał; Kuszewska, Karolina; Asselman, Michel; Denisow, Bożena; Stawiarz, Ernest; Woyciechowski, Michał; Weiner, January

2017-01-01

The least understood aspects of the nutritional needs of bees are the elemental composition of pollen and the bees' need for a stoichiometrically balanced diet containing the required proportions of nutrients. Reduced plant diversity has been proposed as an indirect factor responsible for the pollinator crisis. We suggest stoichiometric mismatch resulting from a nutritionally unbalanced diet as a potential direct factor. The concentrations and stoichiometric ratios of C, N, S, P, K, Na, Ca, Mg, Fe, Zn, Mn, and Cu were studied in the bodies of honeybees of various castes and sexes and in the nectar and pollen of various plant species. A literature review of the elemental composition of pollen was performed. We identified possible co-limitations of bee growth and development resulting mainly from the scarcity of Na, S, Cu, P and K, and possibly Zn and N, in pollen. Particular castes and sexes face specific limitations. Concentrations of potentially limiting elements in pollen revealed high taxonomic diversity. High floral diversity may be necessary to maintain populations of pollen eaters. Single-species crop plantations, even if these species are rich in nectar and pollen, might limit bee growth and development, not allowing for gathering nutrients in adequate proportions. However, particular plant species may play greater roles than others in balancing honeybee diets. Therefore, we suggest specific plant species that may (1) ensure optimal growth and production of individuals by producing pollen that is exceptionally well balanced stoichiometrically (e.g., clover) or (2) prevent growth and development of honeybees by producing pollen that is extremely unbalanced for bees (e.g., sunflower). Since pollen is generally poor in Na, this element must be supplemented using "dirty water". Nectar cannot supplement the diet with limiting elements. Stoichiometric mismatch should be considered in intervention strategies aimed at improving the nutritional base for bees.

Ecological stoichiometry of the honeybee: Pollen diversity and adequate species composition are needed to mitigate limitations imposed on the growth and development of bees by pollen quality.

Directory of Open Access Journals (Sweden)

Michał Filipiak

Full Text Available The least understood aspects of the nutritional needs of bees are the elemental composition of pollen and the bees' need for a stoichiometrically balanced diet containing the required proportions of nutrients. Reduced plant diversity has been proposed as an indirect factor responsible for the pollinator crisis. We suggest stoichiometric mismatch resulting from a nutritionally unbalanced diet as a potential direct factor. The concentrations and stoichiometric ratios of C, N, S, P, K, Na, Ca, Mg, Fe, Zn, Mn, and Cu were studied in the bodies of honeybees of various castes and sexes and in the nectar and pollen of various plant species. A literature review of the elemental composition of pollen was performed. We identified possible co-limitations of bee growth and development resulting mainly from the scarcity of Na, S, Cu, P and K, and possibly Zn and N, in pollen. Particular castes and sexes face specific limitations. Concentrations of potentially limiting elements in pollen revealed high taxonomic diversity. High floral diversity may be necessary to maintain populations of pollen eaters. Single-species crop plantations, even if these species are rich in nectar and pollen, might limit bee growth and development, not allowing for gathering nutrients in adequate proportions. However, particular plant species may play greater roles than others in balancing honeybee diets. Therefore, we suggest specific plant species that may (1 ensure optimal growth and production of individuals by producing pollen that is exceptionally well balanced stoichiometrically (e.g., clover or (2 prevent growth and development of honeybees by producing pollen that is extremely unbalanced for bees (e.g., sunflower. Since pollen is generally poor in Na, this element must be supplemented using "dirty water". Nectar cannot supplement the diet with limiting elements. Stoichiometric mismatch should be considered in intervention strategies aimed at improving the nutritional base

Design of planar electron gun for UHF range, CW power inductive output tube

International Nuclear Information System (INIS)

Kaushik, Meenu; Joshi, L.M.

2015-01-01

Inductive Output Tube (lOT) is an amplifier which is now-a-days in demand for scientific applications. For every vacuum tube, electron gun is an important part and in fact considered as the heart of the tube. Hence, designing of this component is very crucial for efficient operation of the device throughout its lifetime. This paper is all about the electromagnetic (EM) design of planar electron gun of 40 kV, 3.5 A beam voltage and beam current respectively, for a 100 kW CW power lOT operating in UHF range. The design considerations and basic equations involved in its design are included in the paper. The gun structure has been optimized for getting the desired beam characteristics. The simulation results including the beam profile along with the beam current are shown using two commercial codes namely TRAK and MAGIC code. Planar shape of electron beam reduces space charge forces in the beam itself and consequently beam energy spread for a given current. The magnetic focusing of planar beam is easier comparative to spherical beam hence, this structure has been adopted for this particular device design. (author)

NaStEP: a proteinase inhibitor essential to self-incompatibility and a positive regulator of HT-B stability in Nicotiana alata pollen tubes.

Science.gov (United States)

Jiménez-Durán, Karina; McClure, Bruce; García-Campusano, Florencia; Rodríguez-Sotres, Rogelio; Cisneros, Jesús; Busot, Grethel; Cruz-García, Felipe

2013-01-01

In Solanaceae, the self-incompatibility S-RNase and S-locus F-box interactions define self-pollen recognition and rejection in an S-specific manner. This interaction triggers a cascade of events involving other gene products unlinked to the S-locus that are crucial to the self-incompatibility response. To date, two essential pistil-modifier genes, 120K and High Top-Band (HT-B), have been identified in Nicotiana species. However, biochemistry and genetics indicate that additional modifier genes are required. We recently reported a Kunitz-type proteinase inhibitor, named NaStEP (for Nicotiana alata Stigma-Expressed Protein), that is highly expressed in the stigmas of self-incompatible Nicotiana species. Here, we report the proteinase inhibitor activity of NaStEP. NaStEP is taken up by both compatible and incompatible pollen tubes, but its suppression in Nicotiana spp. transgenic plants disrupts S-specific pollen rejection; therefore, NaStEP is a novel pistil-modifier gene. Furthermore, HT-B levels within the pollen tubes are reduced when NaStEP-suppressed pistils are pollinated with either compatible or incompatible pollen. In wild-type self-incompatible N. alata, in contrast, HT-B degradation occurs preferentially in compatible pollinations. Taken together, these data show that the presence of NaStEP is required for the stability of HT-B inside pollen tubes during the rejection response, but the underlying mechanism is currently unknown.

Development of a 200 W CW high efficiency traveling wave tube at 12 GHz. [for use in communication technology satellites

Science.gov (United States)

Christensen, J. A.; Tammaru, I.

1974-01-01

The design, development, and test results are reported for an experimental PPM focused, traveling-wave tube that produces 235 watts of CW RF power over 85 MHz centered at 12.080 GHz. The tube uses a coupled cavity RF circuit with a velocity taper for greater than 30 percent basic efficiency. Overall efficiency of 51 percent is achieved by means of a nine stage depressed collector designed at NASA Lewis Research Center. This collector is cooled by direct radiation to deep space.

Functional immunoglobulin E cross-reactivity between Pas n 1 of Bahia grass pollen and other group 1 grass pollen allergens.

Science.gov (United States)

Davies, J M; Dang, T D; Voskamp, A; Drew, A C; Biondo, M; Phung, M; Upham, J W; Rolland, J M; O'Hehir, R E

2011-02-01

Grass pollens are major triggers of allergic rhinitis and asthma, but the immunological relationships between pollen allergens of the subtropical Bahia grass, Paspalum notatum, and temperate grasses are unresolved. To assess serum IgE cross-reactivity between subtropical P. notatum and temperate Lolium perenne (Ryegrass) pollen allergens. Serum IgE reactivities of grass pollen-allergic patients with P. notatum, L. perenne and Cynodon dactylon (Bermuda grass) pollen extracts and their respective purified group 1 allergens, Pas n 1, Lol p 1 and Cyn d 1, were compared by immunoblotting, ELISA and basophil activation. In a cohort of 51 patients from a temperate region, a high frequency of IgE reactivity with each grass pollen was detected, but reactivity with L. perenne pollen was substantially greater than with P. notatum and C. dactylon pollen. Similarly, serum IgE reactivity with Lol p 1 was greater than with Pas n 1 or Cyn d 1. For seven of eight sera studied in detail, asymmetric serum IgE cross-reactivity was observed; L. perenne pollen inhibited IgE reactivity with P. notatum pollen but not the converse, and IgE reactivity with Pas n 1 was inhibited by Lol p 1 but IgE reactivity with Lol p 1 was not inhibited by Pas n 1 or Cyn d 1. Importantly, P. notatum pollen and Pas n 1 activated basophils in grass pollen-allergic patients from a temperate region, although stimulation was greater by pollen of L. perenne than P. notatum or C. dactylon, and by Lol p 1 than Pas n 1 or Cyn d 1. In contrast, a cohort of 47 patients from a subtropical region showed similar IgE reactivity with P. notatum and L. perenne pollen, and reciprocal cross-inhibition of IgE reactivity between L. perenne and P. notatum. Pollen allergens of the subtropical P. notatum, including Pas n 1, show clinically relevant IgE cross-reactivity with pollen allergens of L. perenne but also species-specific IgE reactivity. © 2011 Blackwell Publishing Ltd.

A 2 MW, CW, 170 GHz gyrotron for ITER

International Nuclear Information System (INIS)

Piosczyk, B.; Arnold, A.; Alberti, S.

2003-01-01

A 140 GHz gyrotron for CW operation is under development for the stellarator W7-X. With a prototype tube a microwave output power of about 0.9 MW has been obtained in pulses up to 180 s, limited by the capability of the high voltage power supply. The development work on coaxial cavity gyrotrons has demonstrated the feasibility of manufacturing of a 2 MW, CW 170 GHz tube that could be used for ITER. The problems specific to the coaxial arrangement have been investigated and all relevant information needed for an industrial realization of a coaxial gyrotron have been obtained in short pulse experiments (up to 17 ms). The suitability of critical components for a 2 MW, CW coaxial gyrotron has been studied and a first integrated design has been done. (author)

Safety of panitumumab-IRDye800CW and cetuximab-IRDye800CW for fluorescence-guided surgical navigation in head and neck cancers.

Science.gov (United States)

Gao, Rebecca W; Teraphongphom, Nutte; de Boer, Esther; van den Berg, Nynke S; Divi, Vasu; Kaplan, Michael J; Oberhelman, Nicholas J; Hong, Steven S; Capes, Elissa; Colevas, A Dimitrios; Warram, Jason M; Rosenthal, Eben L

2018-01-01

Purpose: To demonstrate the safety and feasibility of leveraging therapeutic antibodies for surgical imaging. Procedures: We conducted two phase I trials for anti-epidermal growth factor receptor antibodies cetuximab-IRDye800CW (n=12) and panitumumab-IRDye800CW (n=15). Adults with biopsy-confirmed head and neck squamous cell carcinoma scheduled for standard-of-care surgery were eligible. For cetuximab-IRDye800CW, cohort 1 was intravenously infused with 2.5 mg/m 2 , cohort 2 received 25 mg/m 2 , and cohort 3 received 62.5 mg/m 2 . For panitumumab-IRDye800CW, cohorts received 0.06 mg/kg, 0.5 mg/kg, and 1 mg/kg, respectively. Electrocardiograms and blood samples were obtained, and patients were followed for 30 days post-study drug infusion. Results: Both fluorescently labeled antibodies had similar pharmacodynamic properties and minimal toxicities. Two infusion reactions occurred with cetuximab and none with panitumumab. There were no grade 2 or higher toxicities attributable to cetuximab-IRDye800CW or panitumumab-IRDye800CW; fifteen grade 1 adverse events occurred with cetuximab-IRDye800CW, and one grade 1 occurred with panitumumab-IRDye800CW. There were no significant differences in QTc prolongation between the two trials (p=0.8). Conclusions: Panitumumab-IRDye800CW and cetuximab-IRDye800CW have toxicity and pharmacodynamic profiles that match the parent compound, suggesting that other therapeutic antibodies may be repurposed as imaging agents with limited preclinical toxicology data.

Effect of X-rays and u.v.-light on the levels of NAD(P), NAD(P)H and hydroxyproline in Pinus silvestris pollen

International Nuclear Information System (INIS)

Zelles, L.

1978-01-01

Pollen grains of Pinus Silvestris were irradiated with stimulating and inhibiting doses of X-rays and u.v.-light and the levels of NAD(P), NAD(P)H and hydroxyproline determined during tube growth. Pollen grains irradiated with stimulating doses of X-rays and u.v.-light developed longer tubes, while grains irradiated with inhibiting doses of X-rays and u.v.-light developed shorter tubes than the unirradiated controls. After 32 hr of incubation, the levels of NAD(P), NAD(P)H and hydroxyproline were at their lowest compared with unirradiated pollen. In samples with stimulating doses of irradiation NAD(P) reached its maximum earlier than in samples with inhibiting irradiation. The ratio between the concentrations of NAD(P) and NAD(P)H in the irradiated samples was higher than in the unirradiated control. The hydroxyproline content was higher in irradiated than in unirradiated pollen. (author)

Evidence for DNA repair after ultraviolet irradiation of Petunia hybrida pollen

International Nuclear Information System (INIS)

Jackson, J.F.; Linskens, H.F.; Katholieke Universiteit Nijmegen; Katholike Universiteit Nijmegen

1978-01-01

Ultraviolet irradiation of Petunia hybrida pollen led to an unscheduled labelling of pollen DNA by 3 H-thymidine during the early stages of germination. Hydroxyurea increased this DNA labelling, while added boron, required absolutely for pollen germination, tube elongation and tube generative cell mitosis, was not needed for this repair-like DNA synthesis. (orig.) [de

Exposure to environmentally-relevant levels of ozone negatively influence pollen and fruit development.

Science.gov (United States)

Gillespie, Colin; Stabler, Daniel; Tallentire, Eva; Goumenaki, Eleni; Barnes, Jeremy

2015-11-01

A combination of in vitro and in vivo studies on tomato (Lycopersicon esculentum Mill. cv. Triton) revealed that environmentally-relevant levels of ozone (O3) pollution adversely affected pollen germination, germ tube growth and pollen-stigma interactions - pollen originating from plants raised in charcoal-Purafil(®) filtered air (CFA) exhibited reduced germ tube development on the stigma of plants exposed to environmentally-relevant levels of O3. The O3-induced decline in in vivo pollen viability was reflected in increased numbers of non-fertilized and fertilized non-viable ovules in immature fruit. Negative effects of O3 on fertilization occurred regardless of the timing of exposure, with reductions in ovule viability evident in O3 × CFA and CFA × O3 crossed plants. This suggests O3-induced reductions in fertilization were associated with reduced pollen viability and/or ovule development. Fruit born on trusses independently exposed to 100 nmol mol(-1) O3 (10 h d(-1)) from flowering exhibited a decline in seed number and this was reflected in a marked decline in the weight and size of individual fruit - a clear demonstration of the direct consequence of the effects of the pollutant on reproductive processes. Ozone exposure also resulted in shifts in the starch and ascorbic acid (Vitamin C) content of fruit that were consistent with accelerated ripening. The findings of this study draw attention to the need for greater consideration of, and possibly the adoption of weightings for the direct impacts of O3, and potentially other gaseous pollutants, on reproductive biology during 'risk assessment' exercises. Copyright © 2015 Elsevier Ltd. All rights reserved.

Simple methods for in vitro pollen germination and pollen preservation of selected species of the genus Agave

Directory of Open Access Journals (Sweden)

Sigifredo López Díaz

2008-01-01

Full Text Available Simple methods to evaluate the viability and to preserve Agave tequilana Weber var. azul and A. angustifolia Haw pollen were established. Pollen viability was assessed by improving a growing media and evaluating three common pollen germination media components: sucrose, boric acid, and calcium ion. Optimal germination of pollen was obtained at 0.300 M sucrose, 0.324 mM boric acid, and 1.219 mM calcium nitrate and incubated at a temperature of 25°C. Agave pollen was preserved in olive oil and organic solvents. Olive oil, which is immiscible with water, provides an anhydrous environment and limits available oxygen, conditions similar to those provided by some organic solvents. Fresh pollen was put into eppendorf tubes containing n-butanol, n-propanol, isopropanol, extra virgin olive oil and preserved at -20, 4, and 25°C. The germination of the preserved pollen was scored at different time periods during preservation employing the optimal germination medium. The viability of pollen grains preserved at -20°C in olive oil, proved olive oil as an efficient medium for agave pollen preservation for at least 6 months.

Feasibility study of the EU home team on a 170 GHz 1 MW CW gyrotron for ECH on ITER

International Nuclear Information System (INIS)

Iatrou, C.T.; Kern, S.; Thumm, M.; Moebius, A.; Nickel, H.U.; Horajitra, P.; Wien, A.; Tran, T.M.; Bon Mardion, G.; Pain, M.; Tonon, G.

1995-03-01

The gyrotron system for ECH and burn control on ITER requires at least 50 MW of RF power at frequencies near 170 GHz operating in CW. To meet these requirements, high efficiency gyrotron tubes with ≥1 MW power output capability are necessary, as well as simple coupling to either a quasi-optical or waveguide transmission line. The paper reports the feasibility study on the design of an ITER-relevant gyrotron oscillator at 170 GHz, 1 MW CW employing a diode electron gun, an advanced internal quasi-optical converter, a cryogenically cooled single disk sapphire window, and a depressed potential collector. The operating mode selection and the cavity design is a compromise between many design constraints. (author) 18 figs., 6 tabs., 21 refs

Coconut (Cocos nucifera l.) pollen cryopreservation.

Science.gov (United States)

Karun, A; Sjini, K K; Niral, V; Amarnth, C H; Remya, P; Rajesh, M K; Samsudeen, K; Jerard, B A; Engelmann, F

2014-01-01

Coconut genetic resources are threatened by pests and pathogens, natural hazards and human activities. Cryopreservation is the only method allowing the safe and cost-effective long-term conservation of recalcitrant seed species such as coconut. The objective of this work was to test the effect of cryopreservation and of cryostorage duration on coconut pollen germination and fertility. Pollen of two coconut varieties (West Coast Tall WWCTW and Chowghat Orange Dwarf CODC) was collected in March-May over three successive years, desiccated to 7.5 % moisture content (FW) and cryopreserved by direct immersion in liquid nitrogen. Germination and pollen tube length (PTL) of desiccated and cryopreserved pollen were not significantly different for both WCT and COD over the three harvest months of the three consecutive years of study. Pollen germination ranged from 24 to 32 % in desiccated pollen whereas it was between 26 and 29 % in cryopreserved COD pollen. In the case of WCT, germination ranged from 30 to 31 % in desiccated pollen, while it was between 28 and 32 % in cryopreserved pollen. PTL of cryopreserved pollen ranged between 224-390 nm and 226-396 mm for COD and WCT, respectively. Germination of COD pollen varied between 29.0 and 44.1 % after 4 years and 1.0/1.5 years cryostorage, respectively. Germination of WCT pollen did not change significantly between 0 and 6 years cryostorage, being comprised between 32 (24 h) and 40 % (1.5 years). Germination and vigour of cryopreserved pollen were generally higher compared to that of pollen dried in oven and non-cryopreserved. Normal seed set was observed in COD and WCT palms using pollen cryostored for 6 months and 4 years. Cryopreserved pollen of five Tall and five Dwarf accessions displayed 24-31 % and 25-49 % germination, respectively. These results show that it is now possible to establish pollen cryobanks to contribute to coconut germplasm long-term conservation.

Preliminary design of high-power wave-guide/transmission system for multimegawatt CW requirements of 100 MeV proton Linac

International Nuclear Information System (INIS)

Shrivastava, Purushottam; Wanmode, Y.D.; Hannurkar, P.R.

2002-01-01

Development of a 100 MeV CW proton Linac has been planned at CAT. This Linac will be needing CW rf power in the frequency ranges of 350 MHz and 700 MHz for its RFQ and DTL/CCDTL/SFDTL structures respectively. The power to the accelerating structures will be produced by either 1 MW CW or 250 kW CW klystron/inductive output tubes (HOM IOTs). The power needed by respective feed points in the structure is max. 250 kW which will be powered by splitting the power from 1 MW klystron/klystrode into four channels by using a wave-guide system. In case of using 250 kW tubes the power to the structures will be provided directly from each tube. Two types of wave-guide transmission system have been considered, viz WR 2300 for 350 MHz rf needs and WR 1500 for 700 MHz rf needs. The typical wave-guide system has been designed using the 1 MW CW klystron followed by wave-guide filter, dual directional coupler, high-power circulator, three 3 dB magic TEE power dividers to split the main channel into four equal channels of 250 kW each. Each individual channel has dual directional couplers, flexible wave-guide sections and high power ceramic vacuum window. The circulator and each power divider is terminated into the isolated ports by high power CW loads. Out of the four channels three channels have phase shifters. Present paper describes the technological aspects and design specifications-considerations for these stringent requirements. (author)

Floral phenology, secondary pollen presentation and pollination mechanism in Inula racemosa (Angiosperms: Asteraceae

Directory of Open Access Journals (Sweden)

P.A. Shabir

2013-06-01

Full Text Available Inula racemosa Hook. f. is protandrous, discharges pollen grains inside the anther tube and presents pollen secondarily onto the sweeping hairs of the style. The style and stigmatic branches present the yellow clumped pollen grains for pollination. This study describes floral functional morphology and phenology, anther dehiscence and pollen presentation, growth and behaviour of style during anthesis and pollination mechanism of I. racemosa. The species is entomophilous and is characterized by a highly asynchronous sexual phase. A large degree of asynchrony from floret to floret in a capitulum, and capitulum to capitulum in a plant, keeps the pollen dispersed for a longer duration. Two insect families were represented in the pollinator survey: Hymenoptera and Diptera. A significant correlation was observed between the number of capitula visited per bout and foraging time. We discuss morphological features of the ?owers which may enhance the pollen removal rate per bee visit and consequently cause a high visitation and pollination rate.

Arabidopsis WRKY2 and WRKY34 transcription factors interact with VQ20 protein to modulate pollen development and function.

Science.gov (United States)

Lei, Rihua; Li, Xiaoli; Ma, Zhenbing; Lv, Yan; Hu, Yanru; Yu, Diqiu

2017-09-01

Plant male gametogenesis is tightly regulated, and involves complex and precise regulations of transcriptional reprogramming. WRKY transcription factors have been demonstrated to play critical roles in plant development and stress responses. Several members of this family physically interact with VQ motif-containing proteins (VQ proteins) to mediate a plethora of programs in Arabidopsis; however, the involvement of WRKY-VQ complexes in plant male gametogenesis remains largely unknown. In this study, we found that WRKY2 and WKRY34 interact with VQ20 both in vitro and in vivo. Further experiments displayed that the conserved VQ motif of VQ20 is responsible for their physical interactions. The VQ20 protein localizes in the nucleus and specifically expresses in pollens. Phenotypic analysis showed that WRKY2, WRKY34 and VQ20 are crucial for pollen development and function. Mutations of WRKY2, WRKY34 and VQ20 simultaneously resulted in male sterility, with defects in pollen development, germination and tube growth. Further investigation revealed that VQ20 affects the transcriptional functions of its interacting WRKY partners. Complementation evidence supported that the VQ motif of VQ20 is essential for pollen development, as a mutant form of VQ20 in which LVQK residues in the VQ motif were replaced by EDLE did not rescue the phenotype of the w2-1 w34-1 vq20-1 triple-mutant plants. Further expression analysis indicated that WRKY2, WRKY34 and VQ20 co-modulate multiple genes involved in pollen development, germination and tube growth. Taken together, our study provides evidence that VQ20 acts as a key partner of WRKY2 and WKRY34 in plant male gametogenesis. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

Properties of an irradiated heat-treated Zr-2.5Nb pressure tube removed from the NPD reactor

Energy Technology Data Exchange (ETDEWEB)

Chow, C.K. [Atomic Energy of Canada Limited, Pinawa, Manitoba (Canada); Coleman, C.E. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Koike, M.H. [Power Reactor and Nuclear Fuel Development Corp., O-Arai Engineering Centre, O-Arai (Japan); Causey, A.R.; Ells, C.E.; Hosbons, R.R.; Sagat, S.; Urbanic, V.F.; Rodgers, D.K

1997-07-01

Some pressure tubes in reactors moderated by heavy water have been made from heat-treated (HT) Zr-2.5Nb. One such tube was removed from the NPD nuclear reactor after 20 years of operation. An extensive program was carried out jointly by AECL and PNC to evaluate the condition and properties of this pressure tube. The investigations include irradiation creep, tensile, corrosion, delayed hydride cracking (DHC), fatigue, and fracture properties. Results show that: (I) the in-reactor elongation rate is much lower and the transverse strain rates are slightly larger than in cold-worked (CW) Zr-2.5Nb tubes; (2) the tensile properties, hydrogen pickup, threshold stress intensity factor for DHC initiation, DHC velocity, and fatigue crack growth rates were similar to those of the CW Zr-2.5Nb material; (3) the fracture toughness of this tube, as measured by curved compact toughness specimens and burst tests, is slightly higher than the CW tubes. The results were also compared with other heat-treated Zr-2.5Nb materials irradiated in the Fugen reactor. The tube was in excellent condition when removed from the reactor and would have been satisfactory for further service. (author)

Pollen source effects on growth of kernel structures and embryo chemical compounds in maize.

Science.gov (United States)

Tanaka, W; Mantese, A I; Maddonni, G A

2009-08-01

Previous studies have reported effects of pollen source on the oil concentration of maize (Zea mays) kernels through modifications to both the embryo/kernel ratio and embryo oil concentration. The present study expands upon previous analyses by addressing pollen source effects on the growth of kernel structures (i.e. pericarp, endosperm and embryo), allocation of embryo chemical constituents (i.e. oil, protein, starch and soluble sugars), and the anatomy and histology of the embryos. Maize kernels with different oil concentration were obtained from pollinations with two parental genotypes of contrasting oil concentration. The dynamics of the growth of kernel structures and allocation of embryo chemical constituents were analysed during the post-flowering period. Mature kernels were dissected to study the anatomy (embryonic axis and scutellum) and histology [cell number and cell size of the scutellums, presence of sub-cellular structures in scutellum tissue (starch granules, oil and protein bodies)] of the embryos. Plants of all crosses exhibited a similar kernel number and kernel weight. Pollen source modified neither the growth period of kernel structures, nor pericarp growth rate. By contrast, pollen source determined a trade-off between embryo and endosperm growth rates, which impacted on the embryo/kernel ratio of mature kernels. Modifications to the embryo size were mediated by scutellum cell number. Pollen source also affected (P embryo chemical compounds. Negative correlations among embryo oil concentration and those of starch (r = 0.98, P embryos with low oil concentration had an increased (P embryo/kernel ratio and allocation of embryo chemicals seems to be related to the early established sink strength (i.e. sink size and sink activity) of the embryos.

Loss of the Arabidopsis thaliana P₄-ATPase ALA3 reduces adaptability to temperature stresses and impairs vegetative, pollen, and ovule development.

Directory of Open Access Journals (Sweden)

Stephen C McDowell

Full Text Available Members of the P4 subfamily of P-type ATPases are thought to help create asymmetry in lipid bilayers by flipping specific lipids between the leaflets of a membrane. This asymmetry is believed to be central to the formation of vesicles in the secretory and endocytic pathways. In Arabidopsis thaliana, a P4-ATPase associated with the trans-Golgi network (ALA3 was previously reported to be important for vegetative growth and reproductive success. Here we show that multiple phenotypes for ala3 knockouts are sensitive to growth conditions. For example, ala3 rosette size was observed to be dependent upon both temperature and soil, and varied between 40% and 80% that of wild-type under different conditions. We also demonstrate that ala3 mutants have reduced fecundity resulting from a combination of decreased ovule production and pollen tube growth defects. In-vitro pollen tube growth assays showed that ala3 pollen germinated ∼2 h slower than wild-type and had approximately 2-fold reductions in both maximal growth rate and overall length. In genetic crosses under conditions of hot days and cold nights, pollen fitness was reduced by at least 90-fold; from ∼18% transmission efficiency (unstressed to less than 0.2% (stressed. Together, these results support a model in which ALA3 functions to modify endomembranes in multiple cell types, enabling structural changes, or signaling functions that are critical in plants for normal development and adaptation to varied growth environments.

Pollen viability of Salix myrtilloides L. – an endangered species in Poland

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Magdalena Pogorzelec

2016-12-01

Full Text Available Salix myrtilloides L. (swamp willow is the most endangered species among the boreal Salix species in Poland. The number and size of its population have been decreasing constantly since the 1990s. The main aim of the study was to determine the viability of collected S. myrtilloides pollen and optimal conditions for its in vitro germination. The pollen of S. myrtilloides was collected from 25 male individuals from a population growing in the mid-forest peat bog Dekowina (Sobibór Landscape Park in May 2014. Two methods were applied to estimate the viability of fresh and stored pollen: staining pollen with 2% acetocarmine solution and in vitro germinability. Various temperature (11°C, 23°C and light conditions as well as different concentrations of glucose (1%, 2.5%, 5%, or 7.5% were tested for the optimization of in vitro germination. We documented relatively high S. myrtilloides pollen viability. Pollen tube growth was found to be largely affected by both glucose content in the medium and thermal conditions during germination. Fresh pollen germinated most effectively on the medium with 2.5% glucose (stored pollen – in 5% glucose, at 23°C and in the presence of light. We conclude that pollen viability of S. myrtilloides does not seem to be a limiting factor for reproductive success. Moreover, the pollen is not sterile even after storage for 12 months. The S. myrtilloides individuals from the Dekowina peat bog produce viable pollen grains that are able to germinate and therefore it can be used to pollinate other populations present in the Polesie Lubelskie region for gene pool enrichment.

Use of γ-irradiated pollen for the gene transfer in Petunia

International Nuclear Information System (INIS)

Andrejchenko, S.V.; Grodzinskij, D.M.

1986-01-01

Possibility of using gamma-irradiated pollen for the gene transfer in Petunia is shown. Occurrence of gametic transformation provided not only the gene integration and expression but also their transfer to the daughter generations. The described methodical approach to construction of the plant eucariotic cell genome is based not only on its simplicity but also on the fact that gamma-radiation doses of 1000 Gy and higher have no desorganizing effect on the chromatine structure in such a degree that its transcription activity is completely lost. Besides, selective inactivation of the locus radiation in the pollen genome is much assisted by their different radioresistance. Though the gene transfer by gametic transformation is mostly irregular but its probability may be increased by the correct selection of the pollen irradiation dose in a range in which the growth of pollen tube before ovary is conserved and reparation of one-strand and two-strand DNA breaks preventing chromatine fragmentation is suppressed

The proteome and phosphoproteome of maize pollen uncovers fertility candidate proteins.

Science.gov (United States)

Chao, Qing; Gao, Zhi-Fang; Wang, Yue-Feng; Li, Zhe; Huang, Xia-He; Wang, Ying-Chun; Mei, Ying-Chang; Zhao, Biligen-Gaowa; Li, Liang; Jiang, Yu-Bo; Wang, Bai-Chen

2016-06-01

Maize is unique since it is both monoecious and diclinous (separate male and female flowers on the same plant). We investigated the proteome and phosphoproteome of maize pollen containing modified proteins and here we provide a comprehensive pollen proteome and phosphoproteome which contain 100,990 peptides from 6750 proteins and 5292 phosphorylated sites corresponding to 2257 maize phosphoproteins, respectively. Interestingly, among the total 27 overrepresented phosphosite motifs we identified here, 11 were novel motifs, which suggested different modification mechanisms in plants compared to those of animals. Enrichment analysis of pollen phosphoproteins showed that pathways including DNA synthesis/chromatin structure, regulation of RNA transcription, protein modification, cell organization, signal transduction, cell cycle, vesicle transport, transport of ions and metabolisms, which were involved in pollen development, the following germination and pollen tube growth, were regulated by phosphorylation. In this study, we also found 430 kinases and 105 phosphatases in the maize pollen phosphoproteome, among which calcium dependent protein kinases (CDPKs), leucine rich repeat kinase, SNF1 related protein kinases and MAPK family proteins were heavily enriched and further analyzed. From our research, we also uncovered hundreds of male sterility-associated proteins and phosphoproteins that might influence maize productivity and serve as targets for hybrid maize seed production. At last, a putative complex signaling pathway involving CDPKs, MAPKs, ubiquitin ligases and multiple fertility proteins was constructed. Overall, our data provides new insight for further investigation of protein phosphorylation status in mature maize pollen and construction of maize male sterile mutants in the future.

Exposure to environmentally-relevant levels of ozone negatively influence pollen and fruit development

International Nuclear Information System (INIS)

Gillespie, Colin; Stabler, Daniel; Tallentire, Eva; Goumenaki, Eleni; Barnes, Jeremy

2015-01-01

A combination of in vitro and in vivo studies on tomato (Lycopersicon esculentum Mill. cv. Triton) revealed that environmentally-relevant levels of ozone (O_3) pollution adversely affected pollen germination, germ tube growth and pollen-stigma interactions – pollen originating from plants raised in charcoal-Purafil"® filtered air (CFA) exhibited reduced germ tube development on the stigma of plants exposed to environmentally-relevant levels of O_3. The O_3-induced decline in in vivo pollen viability was reflected in increased numbers of non-fertilized and fertilized non-viable ovules in immature fruit. Negative effects of O_3 on fertilization occurred regardless of the timing of exposure, with reductions in ovule viability evident in O_3 × CFA and CFA × O_3 crossed plants. This suggests O_3-induced reductions in fertilization were associated with reduced pollen viability and/or ovule development. Fruit born on trusses independently exposed to 100 nmol mol"−"1 O_3 (10 h d"−"1) from flowering exhibited a decline in seed number and this was reflected in a marked decline in the weight and size of individual fruit – a clear demonstration of the direct consequence of the effects of the pollutant on reproductive processes. Ozone exposure also resulted in shifts in the starch and ascorbic acid (Vitamin C) content of fruit that were consistent with accelerated ripening. The findings of this study draw attention to the need for greater consideration of, and possibly the adoption of weightings for the direct impacts of O_3, and potentially other gaseous pollutants, on reproductive biology during ‘risk assessment’ exercises. - Highlights: • Environmentally-relevant levels of ozone exert negative effects on pollen viability that translate into direct impacts on fruit yield. • Negative impacts of O_3 pollution on reproductive processes were evident regardless of the stage of plant development. • Exposure to environmentally-relevant levels of O_3

Nitric Oxide Binds to and Modulates the Activity of a Pollen Specific Arabidopsis Diacylglycerol Kinase

KAUST Repository

Wong, Aloysius Tze

2014-06-01

Nitric oxide (NO) is an important signaling molecule in plants. In the pollen of Arabidopsis thaliana, NO causes re-orientation of the growing tube and this response is mediated by 3′,5′-cyclic guanosine monophosphate (cGMP). However, in plants, NO-sensors have remained somewhat elusive. Here, the findings of an NO-binding candidate, Arabidopsis thaliana DIACYLGLYCEROL KINASE 4 (ATDGK4; AT5G57690) is presented. In addition to the annotated diacylglycerol kinase domain, this molecule also harbors a predicted heme-NO/oxygen (H-NOX) binding site and a guanylyl cyclase (GC) catalytic domain which have been identified based on the alignment of functionally conserved amino acid residues across species. A 3D model of the molecule was constructed, and from which the locations of the kinase catalytic center, the ATP-binding site, the GC and H-NOX domains were estimated. Docking of ATP to the kinase catalytic center was also modeled. The recombinant ATDGK4 demonstrated kinase activity in vitro, catalyzing the ATP-dependent conversion of sn-1,2-diacylglycerol (DAG) to phosphatidic acid (PA). This activity was inhibited by the mammalian DAG kinase inhibitor R59949 and importantly also by the NO donors diethylamine NONOate (DEA NONOate) and sodium nitroprusside (SNP). Recombinant ATDGK4 also has GC activity in vitro, catalyzing the conversion of guanosine-5\\'-triphosphate (GTP) to cGMP. The catalytic domains of ATDGK4 kinase and GC may be independently regulated since the kinase but not the GC, was inhibited by NO while Ca2+ only stimulates the GC. It is likely that the DAG kinase product, PA, causes the release of Ca2+ from the intracellular stores and Ca2+ in turn activates the GC domain of ATDGK4 through a feedback mechanism. Analysis of publicly available microarray data has revealed that ATDGK4 is highly expressed in the pollen. Here, the pollen tubes of mis-expressing atdgk4 recorded slower growth rates than the wild-type (Col-0) and importantly, they showed altered

Among-species differences in pollen quality and quantity limitation: implications for endemics in biodiverse hotspots.

Science.gov (United States)

Alonso, Conchita; Navarro-Fernández, Carmen M; Arceo-Gómez, Gerardo; Meindl, George A; Parra-Tabla, Víctor; Ashman, Tia-Lynn

2013-11-01

Insufficient pollination is a function of quantity and quality of pollen receipt, and the relative contribution of each to pollen limitation may vary with intrinsic plant traits and extrinsic ecological properties. Community-level studies are essential to evaluate variation across species in quality limitation under common ecological conditions. This study examined whether endemic species are more limited by pollen quantity or quality than non-endemic co-flowering species in three endemic-rich plant communities located in biodiversity hotspots of different continents (Andalusia, California and Yucatan). Natural variations in pollen receipt and pollen tube formation were analysed for 20 insect-pollinated plants. Endemic and non-endemic species that co-flowered were paired in order to estimate and compare the quantity and quality components of pre-zygotic pollination success, obtained through piecewise regression analysis of the relationship between pollen grains and pollen tubes of naturally pollinated wilted flowers. Pollen tubes did not frequently exceed the number of ovules per flower. Only the combination of abundant and good quality pollen and a low number of ovules per flower conferred relief from pre-zygotic pollen limitation in the three stochastic pollination environments studied. Quality of pollen receipt was found to be as variable as quantity among study species. The relative pollination success of endemic and non-endemic species, and its quantity and quality components, was community dependent. Assessing both quality and quantity of pollen receipt is key to determining the ovule fertilization potential of both endemic and widespread plants in biodiverse hotspot regions. Large natural variation among flowers of the same species in the two components and pollen tube formation deserves further analysis in order to estimate the environmental, phenotypic and intraindividual sources of variation that may affect how plants evolve to overcome this limitation in

Biochemical and ultrastructural changes in pollen of Zea mays L. grown under enhanced UV-B radiation

International Nuclear Information System (INIS)

Santos, A.; Almeida, J.M.; Santos, I.; Salema, R.

1998-01-01

The influence of ultraviolet-B (UV-B) radiation on the development of the male gametophyte was studied in Zea mays L. cv. LG12 grown in a growth chamber under PAR light supplemented with UV-B radiation and compared with a second set of plants grown under PAR light. Pollen samples collected from both groups of plants were cultured on germination medium and it was found that UV-B had no effect on pollen germination. Total pollen protein content was not affected but UV-B absorbing pigments increased. Some ultrastructural alterations were observed in pollen and pollen tubes, in particular large amounts of electron dense deposits were seen throughout the cytoplasm and in association with the pollen wall. In mature spikes of UV-B treated plants, anthers retained numerous pollen grains in their loculi while anthers of control plants were almost empty. UV-B treatment delayed flowering by 2±3 d. These results show that UV-B treatment of maize plants interferes with flowering, pollen ultrastructure and anther maturation even though pollen germination is unaffected. The significant increase of UV-B absorbing pigments in pollen grains could represent a defence mechanism that enables plants to complete their reproductive cycle. (author)

Characterization of a pollen-specific cDNA clone from Nicotiana tabacum expressed during microgametogenesis and germination.

Science.gov (United States)

Weterings, K; Reijnen, W; van Aarssen, R; Kortstee, A; Spijkers, J; van Herpen, M; Schrauwen, J; Wullems, G

1992-04-01

This report describes the isolation and characterization of a cDNA clone representing a gene specifically expressed in pollen. A cDNA library was constructed against mRNA from mature pollen of Nicotiana tabacum. It was screened differentially against cDNA from mRNA of leaf and of pollen. One clone, NTPc303, was further characterized. On northern blot this clone hybridizes to a transcript 2100 nucleotides in length. NTPc303 is abundant in pollen. Expression of the corresponding gene is restricted to pollen, because no other generative or vegetative tissue contains transcripts hybridizing to NTPc303. Expression of NTP303 is evolutionarily conserved: homologous transcripts are present in pollen from various plant species. The first NTP303 transcripts are detectable on northern blot at the early bi-nucleate stage and accumulate until the pollen has reached maturity. During germination and pollen tube growth in vitro new NTP303 transcripts appear. This transcription has been proved by northern blots as well as by pulse labelling experiments. Nucleotide sequence analysis revealed that NTPc303 has an open reading frame coding for a predicted protein of 62 kDa. This protein shares homology to ascorbate oxidase and other members of the blue copper oxidase family. A possible function for this clone during pollen germination is discussed.

MICROBIAL QUALITY OF HONEY MIXTURE WITH POLLEN

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Ján Mareček

2011-02-01

Full Text Available Normal 0 21 MicrosoftInternetExplorer4 The aim of this study was evaluation of microbial quality in raw materials (honey, pollen and evaluation of microbial quality in honey mixture with pollen (2.91 % and 3.85 % and also dynamics of microbial groups in honey mixtures with pollen after 14 days storage at the room temperature (approximately 25 °C and in cold store (8 °C. We used dilution plating method for testing of samples. Detections of total plate microbial count (aerobic and anaerobic microorganisms, sporulating bacteria, coliform bacteria, Bifidobacterium sp., Lactobacillus sp. and microscopic fungi were performed. In general, counts of microorganisms decreased in honey mixture with pollen compared to raw pollen and these counts increased compared to natural honey. Total plate count was 5.37 log KTJ.g-1 in pollen; 1.36 log KTJ.g-1 in honey; 2.97 log KTJ.g-1 in honey mixture with 2.91 % pollen and 2.04 log KTJ.g-1 in honey mixture with 3.85 % pollen. Coliform bacteria were detected in pollen (1.77 log KTJ.g-1. Then, we found coliform bacteria in one sample of honey mixtures with pollen (2.91 % - 1.00 log KTJ.g-1.Bifidobacterium species were detected only in raw pollen. We did not findLactobacillus sp. in any of the samples. Microscopic fungi were detected on two cultivating media. Yeasts were present in pollen sample (average 5.39 log KTJ.g-1, honey mixture with 2.91 % pollen (average 2.51 log KTJ.g-1 and honey mixture with 3.85 % pollen (average 1.58 log KTJ.g-1. Filamentous microscopic fungi were detectable in pollen (average 3.38 log KTJ.g-1, in honey (only on one medium: 1.00 log KTJ.g-1, in honey mixture with 2.91 % pollen (average 1.15 log KTJ.g-1 and in honey mixture with 3.85 % pollen (1.71 %. Raw pollen contained microscopic fungi as Absidiasp., Mucor sp., Alternaria sp. andEmericella nidulans. Honey mixture with 2.91 % pollen after storage (14 days contained lower microbial counts when compared with the sample

In Vitro Pollen Germination of Eichhornia crassipes (Mart. Solms: An Insight into its Preferred Mode of Clonal Reproduction

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Somnath BHOWMIK

2012-05-01

Full Text Available Eichhornia crassipes (Mart. Solms is an aquatic invasive weed throughout the tropical and subtropical regions of the world. The plant rarely produces any fruit under natural condition In order to understand the causes of failure of seed set in this plant various aspect of pollen biology were studied. Pollen fertility and pollen viability was assessed using Muntzing� s mixture and in acetic orcein and TTZ, while pollen germination was assessed with different concentrations of sucrose supplemented with boric acid and Ca and Mg salts. The aim of present study was to find out the cause of sexual incompatibility of Eichhornia crassipes (Mart. Solms. In spite of high pollen fertility, pollen viability and pollen germination the species show hardly any fruit set under natural condition. The abnormal pollen germination like curling of pollen tubes, shrinkage of pollen tube tips and bending of pollen tube might be reasons of sexual incompatibility of this species. It is observed that the taxa required comparatively low sucrose concentration (5% for their optimal in vitro pollen germination (54.08%. Boric acid to certain extent also influences the in vitro pollen germination (56.2%. In the present investigation the nature of substrate in association with the effect of Boric acid, CaCO3, MgSO4 on the in vitro pollen germination of Eichhornia crassipes is also worked out. However the tested salts show no significant effect on pollen germination in the present study.

The effect of UV irradiated vegetative and generative nuclei as well as cytoplasm on pollen tube growth of Pinus Silvestris

International Nuclear Information System (INIS)

Zelles, L.; Seibold, H.W.; Ernst, D.E.W.; Technische Univ. Hannover

1976-01-01

Pollen grains of Pinus Silvestris were irradiated with UV-rays, and the stimulation, or restraint of gemination was studied. Gemination of the pollen was retarded by irradiation of the nucleus. This book place proportionally to the increasing doses: The conditions of irradiation and the effects of the stimulation and retardation are described in detail. Different dose rates with different effects on nucleus and cytoplasma are observed. (AJ) [de

Pollen Performance in Clarkia Taxa with Contrasting Mating Systems: Implications for Male Gametophytic Evolution in Selfers and Outcrossers

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Alisa A. Hove

2013-04-01

Full Text Available We tested three predictions regarding the joint evolution of pollen performance and mating system. First, due to the potential for intense intrasexual competition in outcrossing populations, we predicted that outcrossers would produce faster-growing pollen than their selfing relatives. Second, if elevated competition promotes stronger selection on traits that improve pollen performance, then, among-plant variation in pollen performance would be lower in outcrossers than in selfers. Third, given successive generations of adaptation to the same maternal genotype in selfers, we predicted that, in selfing populations (but not in outcrossing ones, pollen would perform better following self- than cross-pollinations. We tested these predictions in field populations of two pairs of Clarkia (Onagraceae sister taxa. Consistent with our predictions, one outcrosser (C. unguiculata exhibited faster pollen germination and less variation in pollen tube growth rate (PTGR among pollen donors than its selfing sister species, C. exilis. Contrary to our predictions, the selfing C. xantiana ssp. parviflora exhibited faster PTGR than the outcrossing ssp. xantiana, and these taxa showed similar levels of variation in this trait. Pollen performance following self- vs. cross-pollinations did not differ within either selfing or outcrossing taxa. While these findings suggest that mating system and pollen performance may jointly evolve in Clarkia, other factors clearly contribute to pollen performance in natural populations.

Arabinogalactan proteins as interactors along the crosstalk between the pollen tube and the female tissues

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Ana Marta Pereira

2016-12-01

Full Text Available Arabinogalactan Proteins (AGPs have long been considered to be implicated in several steps of the reproductive process of flowering plants. Pollen tube growth along the pistil tissues requires a multiplicity of signalling pathways to be activated and turned off precisely, at crucial timepoints, to guarantee successful fertilization and seed production. In the recent years, an outstanding effort has been made by the plant reproduction scientific community in order to better understand this process. This resulted in the discovery of a fairly substantial number of new players essential for reproduction, as well as their modes of action and interactions. Besides all the indications of AGPs involvement in reproduction, there were no convincing evidences about it. Recently, several studies came out to prove what had long been suggested about this complex family of glycoproteins. AGPs consist of a large family of hydroxyproline-rich proteins, predicted to be anchored to the plasma membrane and extremely rich in sugars. These two last characteristics always made them perfect candidates to be involved in signalling mechanisms, in several plant developmental processes. New findings finally relate AGPs to concrete functions in plant reproduction. In this review, it is intended not only to describe how different molecules and signalling pathways are functioning to achieve fertilization, but also to integrate the recent discoveries about AGPs along this process.

SCFSLF-mediated cytosolic degradation of S-RNase is required for cross-pollen compatibility in S-RNase-based self-incompatibility in Petunia hybrida

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Yongbiao eXue

2014-07-01

Full Text Available Many flowering plants adopt self-incompatibility (SI to maintain their genetic diversity. In species of Solanaceae, Plantaginaceae and Rosaceae, SI is genetically controlled by a single S-locus with multiple haplotypes. The S-locus has been shown to encode S-RNases expressed in pistil and multiple SLF (S-locus F-box proteins in pollen controlling the female and male specificity of SI, respectively. S-RNases appear to function as a cytotoxin to reject self-pollen. In addition, SLFs have been shown to form SCF (SKP1/Cullin1/F-box complexes to serve as putative E3 ubiquitin ligase to interact with S-RNases. Previously, two different mechanisms, the S-RNase degradation and the S-RNase compartmentalization, have been proposed as the restriction mechanisms of S-RNase cytotoxicity allowing compatible pollination. In this study, we have provided several lines of evidence in support of the S-RNase degradation mechanism by a combination of cellular, biochemical and molecular biology approaches. First, both immunogold labeling and subcellular fractionation assays showed that two key pollen SI factors, PhSLF-S3L and PhSSK1 (SLF-interacting SKP1-like1 from Petunia hybrida, a Solanaceous species, are co-localized in cytosols of both pollen grains and tubes. Second, PhS3L-RNases are mainly detected in the cytosols of both self and non-self pollen tubes after pollination. Third, we found that both PhS3-RNases and PhS3L-RNases directly interact with PhSLF-S3L by yeast two-hybrid and co-immunoprecipitation assays. Fourth, S-RNases are specifically degraded in compatible pollen tubes by non-self SLF action. Taken together, our results demonstrate that SCFSLF-mediated non-self S-RNase degradation occurs in the cytosol of pollen tube through the ubiquitin/26S proteasome system serving as the major mechanism to neutralize S-RNase cytotoxicity during compatible pollination in P. hybrida.

Time-dependent crack growth in steam generator tube leakage

International Nuclear Information System (INIS)

Chung, H.D.; Lee, J.H.; Park, Y.W.; Choi, Y.H.

2006-01-01

In general, cracks found in steam generator tubes have semi-elliptical shapes and it is assumed to be rectangular shape for conservatism after crack penetration. Hence, the leak and crack growth behavior has not been clearly understood after the elliptical crack penetrates the tube wall. Several experimental results performed by Argonne Nation Laboratory exhibited time-dependent crack growth behavior of rectangular flaws as well as trapezoidal flaws under constant pressure. The crack growth faster than expected was observed in both cases, which is likely attributed to time-dependent crack growth accompanied by fatigue sources such as the interaction between active jet and crack. The stress intensity factor, K 1 , is necessary for the prediction of the observed fatigue crack growth behavior. However, no K 1 solution is available for a trapezoidal flaw. The objective of this study is to develop the stress intensity factor which can be used for the fatigue analysis of a trapezoidal crack. To simplify the analysis, the crack is assumed to be a symmetric trapezoidal shape. A new K 1 formula for axial trapezoidal through-wall cracks was proposed based on the FEM results. (author)

Allelic interaction of F1 pollen sterility loci and abnormal chromosome behaviour caused pollen sterility in intersubspecific autotetraploid rice hybrids.

Science.gov (United States)

He, J H; Shahid, M Q; Li, Y J; Guo, H B; Cheng, X A; Liu, X D; Lu, Y G

2011-08-01

The intersubspecific hybrids of autotetraploid rice has many features that increase rice yield, but lower seed set is a major hindrance in its utilization. Pollen sterility is one of the most important factors which cause intersubspecific hybrid sterility. The hybrids with greater variation in seed set were used to study how the F(1) pollen sterile loci (S-a, S-b, and S-c) interact with each other and how abnormal chromosome behaviour and allelic interaction of F(1) sterility loci affect pollen fertility and seed set of intersubspecific autotetraploid rice hybrids. The results showed that interaction between pollen sterility loci have significant effects on the pollen fertility of autotetraploid hybrids, and pollen fertility further decreased with an increase in the allelic interaction of F(1) pollen sterility loci. Abnormal ultra-structure and microtubule distribution patterns during pollen mother cell (PMC) meiosis were found in the hybrids with low pollen fertility in interphase and leptotene, suggesting that the effect-time of pollen sterility loci interaction was very early. There were highly significant differences in the number of quadrivalents and bivalents, and in chromosome configuration among all the hybrids, and quadrivalents decreased with an increase in the seed set of autotetraploid hybrids. Many different kinds of chromosomal abnormalities, such as chromosome straggling, chromosome lagging, asynchrony of chromosome disjunction, and tri-fission were found during the various developmental stages of PMC meiosis. All these abnormalities were significantly higher in sterile hybrids than in fertile hybrids, suggesting that pollen sterility gene interactions tend to increase the chromosomal abnormalities which cause the partial abortion of male gametes and leads to the decline in the seed set of the autotetraploid rice hybrids. © 2011 The Author(s).

Genetic and cellular analysis of cross-incompatibility in Zea mays.

Science.gov (United States)

Lu, Yongxian; Kermicle, Jerry L; Evans, Matthew M S

2014-03-01

Three genetic systems conferring cross-incompatibility have been described in Zea mays: Teosinte crossing barrier1-strong (Tcb1-s) found in teosinte, and Gametophyte factor1-strong (Ga1-s) and Ga2-s found in maize and teosinte. The reproductive barrier between maize and some weedy teosintes is controlled by the Tcb1-s locus. Multi-generation inheritance experiments on two independent Tcb1-s lineages show that the Tcb1-s barrier is unstable in some maize lines. Reciprocal crosses between Tcb1-s tester plants and three recombinants in the Tcb1-s mapping region demonstrate that the Tcb1-s haplotype contains separable male and female components. In vivo assays of the dynamics of pollen tube growth and pollen tube morphology during rejection of incompatible pollen in silks carrying the Tcb1-s, Ga1-s, or Ga2-s barriers showed that, in all three, pollen tube growth is slower than in compatible crosses at early stages and had ceased by 24 h after pollination. In all three crossing barrier systems, incompatible pollen tubes have clustered callose plugs in contrast to pollen tubes of compatible crosses. Incompatible pollen tubes growing in the Tcb1-s, Ga1-s, and Ga2-s silks have different morphologies: straight, curved, and kinked, respectively. The distinct morphologies suggest that these crossing barriers block incompatible pollen through different mechanisms. This study lays the foundation for cloning the Tcb1 genes and provides clues about the cellular mechanisms involved in pollen rejection in the Tcb1-s, Ga1-s, and Ga2-s crossing barriers.

Comparison of isolate dadih with yeast dadih in improving nutrition quality of Cassava Waste (CW)

Science.gov (United States)

Ginting, N.

2018-03-01

The cassava industry in North Sumatra Province was one of the most significant agricultural industries. Waste from the cassava industry which was called cassava waste/CW/Onggok was used as feed for ruminants such as cattle, sheep and monogastric such as pigs. The low nutrients in CW caused the need to find a way for improving the nutrients quality. This research was conducted with the aim to help livestockers to ferment their livestock feed. This study compared the ability of fermentation between dadih isolate with dadih yeast. Dadih is traditional food in Indonesia where milk is fermented in bamboo tube. Dadih yeast was made by mixing dadih and whey with flour, made in around shape and sun dried. The results showed that pH of CW by dadih isolate was the lowest while crude protein, crude fiber and fat in CW treated with dadih isolate were improved significantly compared either to control or to dadih starter while fermented CW was better than non-fermented CW. It was recommended livestockers to ferment CW by using either by dadih isolate or dadih starter.

A study on compatibilities on transgenic herbicide-resistant rice with wild relatives by using autoradiography of 32P labeled pollen

International Nuclear Information System (INIS)

Liu Linli; Qiang Sheng; Song Xiaoling

2004-01-01

To evaluate the possibility of gene flow through observation of the sexual compatibilities of transgenic herbicide-resistant rice with wild relative by using isotope tracer to label pollen grains, the experiments on radioactivity, tracer mode, autoradiography film and time were conducted. Better procedure was to label pollen grains of transgenic herbicide-resistant rice by culturing the rice in a 1.48 x 10 7 Bq/L 32 P nutrient liquid, to pollinate the labelled pollen grains on the stigmas of barnyard grass (Echinochloa crusgalli var. mitis), Oryza officinalis and weedy rice (Oryza sativa) respectively, and then 3 hour later, to fix these pistils on a piece of glass plate and cover the film of Luck 400 on it for autoradiography. The autoradiographs show that the tube of the transgenic rice's pollens cannot penetrate the stigma of barnyard grass and arrive at embryo sacs to fertilize, so that the possibility of gene flow between them is the lowest; the tube of the labelled pollens can penetrate the stigma of O officinalis and enter the style but can not arrive at embryo sacs to fertilize, so the possibility of gene flow between them is relatively low; and the pollen tube can arrive at the embryo sacs of the weedy rice, so that the possibility of gene flow is relatively high from transgenic herbicide-resistant rice to weedy rice. (authors)

Cloning and characterisation of a putative pollen-specific polygalacturonase gene (CpPG1) differentially regulated during pollen development in zucchini (Cucurbita pepo L.).

Science.gov (United States)

Carvajal, F; Garrido, D; Jamilena, M; Rosales, R

2014-03-01

Studies in zucchini (Cucurbita pepo L. spp. pepo) pollen have been limited to the viability and morphology of the mature pollen grain. The enzyme polygalacturonase (PG) is involved in pollen development and pollination in many species. In this work, we study anther and pollen development of C. pepo and present the cloning and characterisation of a putative PG CpPG1 (Accession no. HQ232488) from pollen cDNA in C. pepo. The predicted protein for CpPG1 has 416 amino acids, with a high homology to other pollen PGs, such as P22 from Oenothera organensis (76%) and PGA3 from Arabidopsis thaliana (73%). CpPG1 belongs to clade C, which comprises PGs expressed in pollen, and presents a 34 amino acid signal peptide for secretion towards the cell wall. DNA-blot analysis revealed that there are at least another two genes that code for PGs in C. pepo. The spatial and temporal accumulation of CpPG1 was studied by semi-quantitative- and qRT-PCR. In addition, mRNA was detected only in anthers, pollen and the rudimentary anthers of bisexual flowers (only present in some zucchini cultivars under certain environmental conditions that trigger anther development in the third whorl of female flowers). However, no expression was detected in cotyledons, stem or fruit. Furthermore, CpPG1 mRNA was accumulated throughout anther development, with the highest expression found in mature pollen. Similarly, exo-PG activity increased from immature anther stages to mature anthers and mature pollen. Overall, these data support the pollen specificity of this gene and suggest an involvement of CpPG1 in pollen development in C. pepo. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.

Design, construction, system integration, and test results of the 1 MW CW RF system for the e-gun cavity in the energy recovery LINAC at Brookhaven National Laboratory

International Nuclear Information System (INIS)

Lenci, S.J.; Eisen, E.L.; Dickey, D.L.; Sainz, J.E.; Utay, P.F.; Zaltsman, A.; Lambiase, R.

2009-01-01

Brookhaven's ERL (Energy Recovery LINAC) requires a 1 MW CW RF system for the superconducting electron gun cavity. The system consists primarily of a klystron tube, transmitter, and High-Voltage Power Supply (HVPS). The 703.75 MHz klystron made by CPl, Inc. provides RF power of 1MW CW with efficiency of 65%. It has a single output window, diode-type electron gun, and collector capable of dissipating the entire beam power. It was fully factory tested including 24-hour heat run at 1.1 MW CWo The solid state HVPS designed by Continental Electronics provides up to 100 kV at low ripple and 2.1 MW CW with over 95% efficiency. With minimal stored energy and a fast shut-down mode no crowbar circuit is needed. Continental 's transmitter includes PLC based user interface and monitoring, RF pre-amplifier, magnet and Vac-Ion pump supplies, cooling water instrumentation, and integral safety interlock system. BNL installed the klystron, HVPS, and transmitter along with other items, such as circulator, water load, and waveguide components. The collaboration of BNL, CPI, and Continental in the design, installation, and testing was essential to the successful operation of the 1MW system

Tradescantia cytogenetic tests (root-tip mitosis, pollen mitosis, pollen mother-cell meiosis). A report of the US Environmental Protection Agency gene-tox program

Energy Technology Data Exchange (ETDEWEB)

Ma, T H

1982-01-01

3 kinds of cytogenetic tests for screening of environmental mutagens were established for Tradescantia, namely, root-tip mitosis, pollen mitosis, and pollen mother-cell meiosis (commonly referred to as the Tradescantia-micronucleus (Trad-MCN) test). All these tests are technically simple, inexpensive, and can yield reliable results in a relatively short time (36 to 72 h). The root-tip mitosis test is suitable only for liquid agents, while pollen mitosis is suitable for both liquid and gaseous agents. Pollen tube mitotic chromosomes are extremely sensitive to mutagens; therefore, they are good materials for detecting very low concentrations of mutagens. Both root-tip mitosis and pollen mitosis tests use chromosome and/or chromatid aberrations as end points for scoring. The Trad-MCN test is suitable for both liquid and gaseous agents. In addition, it is especially suitable for in situ monitoring of water and air pollutants. Of the 12 chemicals tested, 5-fluorouracil and 1,2-dibromoethane indicate that they are very potent mutagens based on the effective dosages used to produce a positive response. Sulfur dioxide, ethyl methanesulfonate, sodium azide, Phosdrin, and Bladex rank next in potency.

Design considerations in achieving 1 MW CW operation with a whispering-gallery-mode gyrotron

International Nuclear Information System (INIS)

Felch, K.; Feinstein, J.; Hess, C.; Huey, H.; Jongewaard, E.; Jory, H.; Neilson, J.; Pendleton, R.; Pirkle, D.; Zitelli, L.

1989-09-01

Varian is developing high-power, CW gyrotrons at frequencies in the range 100 GHz to 150 GHz, for use in electron cyclotron heating applications. Early test vehicles have utilized a TE 15,2,1 interaction cavity, have achieved short-pulse power levels of 820 kW and average power levels of 80 kW at 140 GHz. Present tests are aimed at reaching 400 kW under CW operating conditions and up to 1 MW for short pulse durations. Work is also underway on modifications to the present design that will enable power levels of up to 1 MW CW to be achieved. 7 refs., 2 figs

Comparison of GSM Modulated and CW Radiofrequency Radiation on Cells

International Nuclear Information System (INIS)

Pavicic, I.; Marjanovic, A.M.; Trosic, I.

2011-01-01

The aim of our study was to evaluate and compare effect of global system of mobile (GSM) modulation and continuous wave (CW) radiofrequency radiation (RF) on proliferation ability and viability of V79 Chinese hamster lung cells. Previously prepared samples of cells in culture were exposed for 1, 2 and 3 hours both to 915 MHz GSM modulated and to 935 MHz CW RF field in gigahertz transversal electromagnetic mode cell (GTEM-cell). Electric field strength for cells exposed to GSM modulation was set at 10 V/m and for CW exposed cells was 8.2 V/m. Average specific absorption rate (SAR) was calculated to be for GSM 0.23 W/kg and for CW 0.12 W/kg. V79 samples were plated in concentration of 1x10 4 cells/mL. Cell proliferation was determined by cell counts for each hour of exposure during five post-exposure days. Trypan blue exclusion test was used to determine cell viability. In comparison to control cell samples, proliferation of GSM irradiated cells showed significant decrease after 3 hours of exposure on the second and third post-exposure day. CW exposed cell samples showed significant decrease after 3 hours of exposure on the third post-exposure day. Viability of GSM and CW exposed cells did not significantly differ from matched control cell samples. Both applied RF fields have shown similar effect on cell culture growth, and cell viability of V79 cell line. In addition, applied GSM modulated RF radiation demonstrate bigger influence on proliferation of cells. (author)

Calcium in pollen-pistil interaction in 'Petunia hybrida Hat'. Pt. 3. Localization of Ca2+ ions and Ca2+-ATPase in pollinated pistil

International Nuclear Information System (INIS)

Bednarska, E.; Butowt, R.

1995-01-01

Studies were carried out of Ca 2+ and Ca 2+ -ATPase localization in pollinated (6 and 48 h after pollination) pistils of 'Petunia hybrida'. The results were confronted with Ca 2+ localization in mature pollen grain and in unpollinated pistil. It has been found that after pollination the number of Ca 2+ sequestered in the stigmal exudate and in the sporoderm of the pollen grain gets lower. That phenomenon was associated with the appearance of a large number of Sb/Ca precipitates in the submembrane cytoplasm of the germinating pollen. In the vacuolized pollen grain, i.e. grown into a pollen tube, there were only a few precipitates. In the pollen tube, Ca 2+ were found in the organelles of the tip cytoplasm and in the external pectin cell wall. Studies with the use of 45 Ca 2+ have revealed that the source of calcium ions incorporated into the pollen tube tip and its pectin wall is the transmitting tract of the style. In the transmitting tract overgrown with pollen tubes, Ca 2+ were localized in the intercellular matrix and in the transmitting cell. Sb/Ca precipitates occurred in the nuclei, around the secretary vesicles and on the plasmalemma in the transverse walls region. Elevated Ca 2+ level was found in degenerating cells (inhibited pollen tubes, transmitting cells, nucellar cells). The progressing degeneration process of the cells of the transmitting tract of the pollinated pistil was associated with a decrease in the activity of plasmalemma Ca 2+ -ATPase. (author). 30 refs, 19 figs

Polyploidy Enhances F1 Pollen Sterility Loci Interactions That Increase Meiosis Abnormalities and Pollen Sterility in Autotetraploid Rice1[OPEN

Science.gov (United States)

Wu, Jinwen; Chen, Lin; Chen, Zhixiong; Wang, Lan; Lu, Yonggen

2015-01-01

Intersubspecific autotetraploid rice (Oryza sativa ssp. indica × japonica) hybrids have greater biological and yield potentials than diploid rice. However, the low fertility of intersubspecific autotetraploid hybrids, which is largely caused by high pollen abortion rates, limits their commercial utility. To decipher the cytological and molecular mechanisms underlying allelic interactions in autotetraploid rice, we developed an autotetraploid rice hybrid that was heterozygous (SiSj) at F1 pollen sterility loci (Sa, Sb, and Sc) using near-isogenic lines. Cytological studies showed that the autotetraploid had higher percentages (>30%) of abnormal chromosome behavior and aberrant meiocytes (>50%) during meiosis than did the diploid rice hybrid control. Analysis of gene expression profiles revealed 1,888 genes that were differentially expressed between the autotetraploid and diploid hybrid lines at the meiotic stage, among which 889 and 999 were up- and down-regulated, respectively. Of the 999 down-regulated genes, 940 were associated with the combined effect of polyploidy and pollen sterility loci interactions (IPE). Gene Ontology enrichment analysis identified a prominent functional gene class consisting of seven genes related to photosystem I (Gene Ontology 0009522). Moreover, 55 meiosis-related or meiosis stage-specific genes were associated with IPE in autotetraploid rice, including Os02g0497500, which encodes a DNA repair-recombination protein, and Os02g0490000, which encodes a component of the ubiquitin-proteasome pathway. These results suggest that polyploidy enhances epistatic interactions between alleles of pollen sterility loci, thereby altering the expression profiles of important meiosis-related or meiosis stage-specific genes and resulting in high pollen sterility. PMID:26511913

Calculation of vapour bubble growth on the lower generatrix of horizontal tubes

International Nuclear Information System (INIS)

Chajka, V.D.

1987-01-01

The known models of vapour bubble growth are compared with experimental data. Cinematographic study of vapour formation during water boiling was carried out with elements of horizontal tubes of copper 10, 16, 24, 34 and 70 mm in diameter under the pressure of 100 kPa and specific thermal loadings of 20 and 40 kW/m 2 . According to the experimental data the main volume of vapour phase is occupied by vapour bubbles from the lower part of the horizontal tube. Five stages of vapour bubble growth on the lower generatrix of the horizontal tube: nucleation, growth to the point of breaking off from nucleate centre, the breaking off from the nucleate centre, the tube surface flowing around during floating up, the breaking off from the tube surface, were singled out. The shape of vapour volume varied during the whole period of the bubble growth and it was mainly determined by the horizontal tube diameter. The change of vapour bubble radius in time is the function of the horizontal tube diameter. Comparison of the experimental data with the known models of vapour bubble growth has shown, that every stage of vapour bubble growth on the lower generatrix of the tube is determined by the complex of thermal and hydrodynamic conditions, the effect of which depends on the horizontal tube diameter

Improved resection and prolonged overall survival with PD-1-IRDye800CW fluorescence probe-guided surgery and PD-1 adjuvant immunotherapy in 4T1 mouse model

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Du Y

2017-11-01

Full Text Available Yang Du,1,2,* Ting Sun,3,* Xiaolong Liang,4,* Yuan Li,3 Zhengyu Jin,3 Huadan Xue,3 Yihong Wan,5 Jie Tian1,2 1CAS Key Laboratory of Molecular Imaging, 2The State Key Laboratory of Management and Control for Complex Systems, Institute of Automation, Chinese Academy of Sciences, 3Department of Radiology, Peking Union Medical College Hospital, 4Department of Ultrasound, Peking University Third Hospital, Beijing, China; 5Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA *These authors contributed equally to this work Abstract: An intraoperative technique to accurately identify microscopic tumor residuals could decrease the risk of positive surgical margins. Several lines of evidence support the expression and immunotherapeutic effect of PD-1 in breast cancer. Here, we sought to develop a fluorescence-labeled PD-1 probe for in vivo breast tumor imaging and image-guided surgery. The efficacy of PD-1 monoclonal antibody (PD-1 mAb as adjuvant immunotherapy after surgery was also assessed. PD-1-IRDye800CW was developed and examined for its application in tumor imaging and image-guided tumor resection in an immunocompetent 4T1 mouse tumor model. Fluorescence molecular imaging was performed to monitor probe biodistribution and intraoperative imaging. Bioluminescence imaging was performed to monitor tumor growth and evaluate postsurgical tumor residuals, recurrences, and metastases. The PD-1-IRDye800CW exhibited a specific signal at the tumor region compared with the IgG control. Furthermore, PD-1-IRDye800CW-guided surgery combined with PD-1 adjuvant immunotherapy inhibited tumor regrowth and microtumor metastases and thus improved survival rate. Our study demonstrates the feasibility of using PD-1-IRDye800CW for breast tumor imaging and image-guided tumor resection. Moreover, PD-1 mAb adjuvant immunotherapy reduces cancer recurrences and metastases emanating from tumor residuals. Keywords: PD-1, programmed cell

The LuWD40-1 gene encoding WD repeat protein regulates growth and pollen viability in flax (Linum Usitatissimum L.).

Science.gov (United States)

Kumar, Santosh; Jordan, Mark C; Datla, Raju; Cloutier, Sylvie

2013-01-01

As a crop, flax holds significant commercial value for its omega-3 rich oilseeds and stem fibres. Canada is the largest producer of linseed but there exists scope for significant yield improvements. Implementation of mechanisms such as male sterility can permit the development of hybrids to assist in achieving this goal. Temperature sensitive male sterility has been reported in flax but the leakiness of this system in field conditions limits the production of quality hybrid seeds. Here, we characterized a 2,588 bp transcript differentially expressed in male sterile lines of flax. The twelve intron gene predicted to encode a 368 amino acid protein has five WD40 repeats which, in silico, form a propeller structure with putative nucleic acid and histone binding capabilities. The LuWD40-1 protein localized to the nucleus and its expression increased during the transition and continued through the vegetative stages (seed, etiolated seedling, stem) while the transcript levels declined during reproductive development (ovary, anthers) and embryonic morphogenesis of male fertile plants. Knockout lines for LuWD40-1 in flax failed to develop shoots while overexpression lines showed delayed growth phenotype and were male sterile. The non-viable flowers failed to open and the pollen grains from these flowers were empty. Three independent transgenic lines overexpressing the LuWD40-1 gene had ∼80% non-viable pollen, reduced branching, delayed flowering and maturity compared to male fertile genotypes. The present study provides new insights into a male sterility mechanism present in flax.

The LuWD40-1 gene encoding WD repeat protein regulates growth and pollen viability in flax (Linum Usitatissimum L..

Directory of Open Access Journals (Sweden)

Santosh Kumar

Full Text Available As a crop, flax holds significant commercial value for its omega-3 rich oilseeds and stem fibres. Canada is the largest producer of linseed but there exists scope for significant yield improvements. Implementation of mechanisms such as male sterility can permit the development of hybrids to assist in achieving this goal. Temperature sensitive male sterility has been reported in flax but the leakiness of this system in field conditions limits the production of quality hybrid seeds. Here, we characterized a 2,588 bp transcript differentially expressed in male sterile lines of flax. The twelve intron gene predicted to encode a 368 amino acid protein has five WD40 repeats which, in silico, form a propeller structure with putative nucleic acid and histone binding capabilities. The LuWD40-1 protein localized to the nucleus and its expression increased during the transition and continued through the vegetative stages (seed, etiolated seedling, stem while the transcript levels declined during reproductive development (ovary, anthers and embryonic morphogenesis of male fertile plants. Knockout lines for LuWD40-1 in flax failed to develop shoots while overexpression lines showed delayed growth phenotype and were male sterile. The non-viable flowers failed to open and the pollen grains from these flowers were empty. Three independent transgenic lines overexpressing the LuWD40-1 gene had ∼80% non-viable pollen, reduced branching, delayed flowering and maturity compared to male fertile genotypes. The present study provides new insights into a male sterility mechanism present in flax.

Calcium in pollen-pistil interaction in `Petunia hybrida Hat`. Pt. 3. Localization of Ca{sup 2+} ions and Ca{sup 2+}-ATPase in pollinated pistil

Energy Technology Data Exchange (ETDEWEB)

Bednarska, E.; Butowt, R. [Uniwersytet Mikolaja Kopernika, Torun (Poland)

1995-12-31

Studies were carried out of Ca{sup 2+} and Ca{sup 2+}-ATPase localization in pollinated (6 and 48 h after pollination) pistils of `Petunia hybrida`. The results were confronted with Ca{sup 2+} localization in mature pollen grain and in unpollinated pistil. It has been found that after pollination the number of Ca{sup 2+} sequestered in the stigmal exudate and in the sporoderm of the pollen grain gets lower. That phenomenon was associated with the appearance of a large number of Sb/Ca precipitates in the submembrane cytoplasm of the germinating pollen. In the vacuolized pollen grain, i.e. grown into a pollen tube, there were only a few precipitates. In the pollen tube, Ca{sup 2+} were found in the organelles of the tip cytoplasm and in the external pectin cell wall. Studies with the use of {sup 45}Ca{sup 2+} have revealed that the source of calcium ions incorporated into the pollen tube tip and its pectin wall is the transmitting tract of the style. In the transmitting tract overgrown with pollen tubes, Ca{sup 2+} were localized in the intercellular matrix and in the transmitting cell. Sb/Ca precipitates occurred in the nuclei, around the secretary vesicles and on the plasmalemma in the transverse walls region. Elevated Ca{sup 2+} level was found in degenerating cells (inhibited pollen tubes, transmitting cells, nucellar cells). The progressing degeneration process of the cells of the transmitting tract of the pollinated pistil was associated with a decrease in the activity of plasmalemma Ca{sup 2+}-ATPase. (author). 30 refs, 19 figs.

First 200 kW CW operation of a 60 GHz gyrotron

International Nuclear Information System (INIS)

Jory, H.; Bier, R.; Evans, S.; Felch, K.; Fox, L.; Huey, H.; Shively, J.; Spang, S.

1983-01-01

The gyrotron is a microwave tube which employs the electron cyclotron maser interaction to produce high power output at millimeter wavelengths. It has important and growing applications for heating of plasmas in controlled thermonuclear fusion experiments. The Varian 60 GHz gyrotron has recently generated microwave power in excess of 200 kW during CW operation, wth excellent dynamic range and operating stability. This is the highest average power ever produced by a microwave tube in the millimeter wave region. A description of the gyrotron design and test results are presented

Pollen lipidomics: lipid profiling exposes a notable diversity in 22 allergenic pollen and potential biomarkers of the allergic immune response.

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Mohamed Elfatih H Bashir

Full Text Available BACKGROUND/AIM: Pollen grains are the male gametophytes that deliver sperm cells to female gametophytes during sexual reproduction of higher plants. Pollen is a major source of aeroallergens and environmental antigens. The pollen coat harbors a plethora of lipids that are required for pollen hydration, germination, and penetration of the stigma by pollen tubes. In addition to proteins, pollen displays a wide array of lipids that interact with the human immune system. Prior searches for pollen allergens have focused on the identification of intracellular allergenic proteins, but have largely overlooked much of the extracellular pollen matrix, a region where the majority of lipid molecules reside. Lipid antigens have attracted attention for their potent immunoregulatory effects. By being in close proximity to allergenic proteins on the pollen surface when they interact with host cells, lipids could modify the antigenic properties of proteins. METHODOLOGY/PRINCIPAL FINDINGS: We performed a comparative pollen lipid profiling of 22 commonly allergenic plant species by the use of gas chromatography-mass spectroscopy, followed by detailed data mining and statistical analysis. Three experiments compared pollen lipid profiles. We built a database library of the pollen lipids by matching acquired pollen-lipid mass spectra and retention times with the NIST/EPA/NIH mass-spectral library. We detected, identified, and relatively quantified more than 106 lipid molecular species including fatty acids, n-alkanes, fatty alcohols, and sterols. Pollen-derived lipids stimulation up-regulate cytokines expression of dendritic and natural killer T cells co-culture. CONCLUSIONS/SIGNIFICANCE: Here we report on a lipidomic analysis of pollen lipids that can serve as a database for identifying potential lipid antigens and/or novel candidate molecules involved in allergy. The database provides a resource that facilitates studies on the role of lipids in the

Ragweed (Ambrosia) pollen source inventory for Austria.

Science.gov (United States)

Karrer, G; Skjøth, C A; Šikoparija, B; Smith, M; Berger, U; Essl, F

2015-08-01

This study improves the spatial coverage of top-down Ambrosia pollen source inventories for Europe by expanding the methodology to Austria, a country that is challenging in terms of topography and the distribution of ragweed plants. The inventory combines annual ragweed pollen counts from 19 pollen-monitoring stations in Austria (2004-2013), 657 geographical observations of Ambrosia plants, a Digital Elevation Model (DEM), local knowledge of ragweed ecology and CORINE land cover information from the source area. The highest mean annual ragweed pollen concentrations were generally recorded in the East of Austria where the highest densities of possible growth habitats for Ambrosia were situated. Approximately 99% of all observations of Ambrosia populations were below 745m. The European infection level varies from 0.1% at Freistadt in Northern Austria to 12.8% at Rosalia in Eastern Austria. More top-down Ambrosia pollen source inventories are required for other parts of Europe. A method for constructing top-down pollen source inventories for invasive ragweed plants in Austria, a country that is challenging in terms of topography and ragweed distribution. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

The effect of oleander glycosides on the germination of pollen grains and the mitosis of the generative nucleus in Tradescantia bracteata Small and Allium cepa L.

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J. A. Tarkowska

2015-01-01

Full Text Available The effect of water solution of a mixture of glycosides from oleander (Nerium oleander L. on the germination of pollen grains and on the mitosis of the generative nucleus in Tradescantia bracteata Small and Allium cepa L. has been studied. An inhibition of the germination and of the growth of pollen tubes was observed, proportionally to the concentration of glycosides. The pollen grains of A. cepa are more sensitive. The disturbances in mitosis lead to the formation of two or more uneven-sized doughter nuclei, or to the formation of restitution nuclei. These anomalies are more numerous in T. bracteata. From these results d t appears that pollen grains of A. cepa are characterized by a generally high physiological sensitivity and a small mitotic sensitivity, wheras for T. bracteata the opposite is true.

THE BIOMASS OF Streptococcus thermophilus AND Bifidobacterium longum IN DAIRY MEDIUM WITH BEE POLLEN

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N. N. Lomova

2015-02-01

Full Text Available The present study was carried out to investigate the effect of adding different concentrations of bee pollen on the biomass of Streprococus thermophilus and B. longum in the dairy environment. Sampling, preparation and conducting of tests were performed by standard methods of analysis. The counts of Str. thermophilus and B. longum were carried out by using M17 and MRS agar media. The phases growth were determined graphically. Established, that bee pollen stimulates the accumulation of biomass Str. thermophilus on 9–15%, and B. longum – on 2,3–12,7% in an amount of up to 0.2–1.0%. Bee pollen reduces the duration of the lag phase for both types of microorganisms almost to its complete disappearance (1.0%. Pollen (1% prolong stationary phase for streptococci and bifidobacteria to 30% and 20%, respectively. And also, will provide the biomass in the amount of 6 ± 0,1·109 CFU/cm3 (Str. Thermophilus and 2,8 ± 0,1·108 CFU/cm3 (B. longum. Str. thermophilus and B. longum readily assimilate essential micronutrients pollen. Components of bee pollen can act growth stimulants (bifidogenic factor for the studied strains. The data obtained will form the basis of biotechnology dairy drink with bee products.

Formation and function of a new pollen aperture pattern in angiosperms: The proximal sulcus of Tillandsia leiboldiana (Bromeliaceae).

Science.gov (United States)

Albert, Béatrice; Matamoro-Vidal, Alexis; Raquin, Christian; Nadot, Sophie

2010-02-01

Pollen grains are generally surrounded by an extremely resistant wall interrupted in places by apertures that play a key role in reproduction; pollen tube growth is initiated at these sites. The shift from a proximal to distal aperture location is a striking innovation in seed plant reproduction. Reversals to proximal aperture position have only very rarely been described in angiosperms. The genus Tillandsia belongs to the Bromeliaceae family, and its aperture pattern has been described as distal monosulcate, the most widespread aperture patterns recorded in monocots and basal angiosperms. Here we report developmental and functional elements to demonstrate that the sulcate aperture in Tillandsia leiboldiana is not distal as previously described but proximal. Postmeitotic tetrad observation indicates unambiguously the proximal position of the sulcus, and in vitro germination of pollen grains confirms that the aperture is functional. This is the first report of a sulcate proximal aperture with proximal germination. The observation of microsporogenesis reveals specific features in the patterns of callose thickenings in postmeiotic tetrads.

Fatigue crack growth behaviour of 21/4Cr1Mo steel tube at elevated temperature

International Nuclear Information System (INIS)

Bulloch, J.H.; Buchanan, L.W.

1987-01-01

The fatigue crack growth characteristics of 21/4Cr1Mo steel tube have been examined at 588 0 C over the frequency range 0.02-20 Hz and dwell time range 10-960 min. All tests were conducted under load control in laboratory air at an R-ratio of 0.5. The elevated temperature fatigue crack growth characteristics were adequately described in terms of the stress intensity range ΔKAPPA. The continuous cyclic test data exhibited a significant effect of frequency that agreed well with predicted effects using a simple mathematical model of the high temperature fatigue process. With the dwell time range of 10-100 min there was a significant dwell time effect on the critical ΔKAPPA level for creep-fatigue interactive growth. At dwell times > 100 min the dwell time effect saturates. When creep-fatigue interactive growth occurs, growth rates reside above the maximum for continuum-controlled fatigue crack growth, and exhibit a da/dN varies as ΔKAPPA 10 dependence; failure is then intergranular in nature. (author)

Aberrant Classopollis pollen reveals evidence for unreduced (2n) pollen in the conifer family Cheirolepidiaceae during the Triassic–Jurassic transition

Science.gov (United States)

Kürschner, Wolfram M.; Batenburg, Sietske J.; Mander, Luke

2013-01-01

Polyploidy (or whole-genome doubling) is a key mechanism for plant speciation leading to new evolutionary lineages. Several lines of evidence show that most species among flowering plants had polyploidy ancestry, but it is virtually unknown for conifers. Here, we study variability in pollen tetrad morphology and the size of the conifer pollen type Classopollis extracted from sediments of the Triassic–Jurassic transition, 200 Ma. Classopollis producing Cheirolepidiaceae were one of the most dominant and diverse groups of conifers during the Mesozoic. We show that aberrant pollen Classopollis tetrads, triads and dyads, and the large variation in pollen size indicates the presence of unreduced (2n) pollen, which is one of the main mechanisms in modern polyploid formation. Polyploid speciation may explain the high variability of growth forms and adaptation of these conifers to different environments and their resistance to extreme growth conditions. We suggest that polyploidy may have also reduced the extinction risk of these conifers during the End-Triassic biotic crisis. PMID:23926159

A prognostic pollen emissions model for climate models (PECM1.0

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M. C. Wozniak

2017-11-01

Full Text Available We develop a prognostic model called Pollen Emissions for Climate Models (PECM for use within regional and global climate models to simulate pollen counts over the seasonal cycle based on geography, vegetation type, and meteorological parameters. Using modern surface pollen count data, empirical relationships between prior-year annual average temperature and pollen season start dates and end dates are developed for deciduous broadleaf trees (Acer, Alnus, Betula, Fraxinus, Morus, Platanus, Populus, Quercus, Ulmus, evergreen needleleaf trees (Cupressaceae, Pinaceae, grasses (Poaceae; C3, C4, and ragweed (Ambrosia. This regression model explains as much as 57 % of the variance in pollen phenological dates, and it is used to create a climate-flexible phenology that can be used to study the response of wind-driven pollen emissions to climate change. The emissions model is evaluated in the Regional Climate Model version 4 (RegCM4 over the continental United States by prescribing an emission potential from PECM and transporting pollen as aerosol tracers. We evaluate two different pollen emissions scenarios in the model using (1 a taxa-specific land cover database, phenology, and emission potential, and (2 a plant functional type (PFT land cover, phenology, and emission potential. The simulated surface pollen concentrations for both simulations are evaluated against observed surface pollen counts in five climatic subregions. Given prescribed pollen emissions, the RegCM4 simulates observed concentrations within an order of magnitude, although the performance of the simulations in any subregion is strongly related to the land cover representation and the number of observation sites used to create the empirical phenological relationship. The taxa-based model provides a better representation of the phenology of tree-based pollen counts than the PFT-based model; however, we note that the PFT-based version provides a useful and climate-flexible emissions

Two Hydroxyproline Galactosyltransferases, GALT5 and GALT2, Function in Arabinogalactan-Protein Glycosylation, Growth and Development in Arabidopsis.

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Debarati Basu

Full Text Available Hydroxyproline-O-galactosyltransferase (GALT initiates O-glycosylation of arabinogalactan-proteins (AGPs. We previously characterized GALT2 (At4g21060, and now report on functional characterization of GALT5 (At1g74800. GALT5 was identified using heterologous expression in Pichia and an in vitro GALT assay. Product characterization showed GALT5 specifically adds galactose to hydroxyproline in AGP protein backbones. Functions of GALT2 and GALT5 were elucidated by phenotypic analysis of single and double mutant plants. Allelic galt5 and galt2 mutants, and particularly galt2 galt5 double mutants, demonstrated lower GALT activities and reductions in β-Yariv-precipitated AGPs compared to wild type. Mutant plants showed pleiotropic growth and development phenotypes (defects in root hair growth, root elongation, pollen tube growth, flowering time, leaf development, silique length, and inflorescence growth, which were most severe in the double mutants. Conditional mutant phenotypes were also observed, including salt-hypersensitive root growth and root tip swelling as well as reduced inhibition of pollen tube growth and root growth in response to β-Yariv reagent. These mutants also phenocopy mutants for an AGP, SOS5, and two cell wall receptor-like kinases, FEI1 and FEI2, which exist in a genetic signaling pathway. In summary, GALT5 and GALT2 function as redundant GALTs that control AGP O-glycosylation, which is essential for normal growth and development.

The PTI1-like kinase ZmPti1a from maize (Zea mays L.) co-localizes with callose at the plasma membrane of pollen and facilitates a competitive advantage to the male gametophyte.

Science.gov (United States)

Herrmann, Markus M; Pinto, Sheena; Kluth, Jantjeline; Wienand, Udo; Lorbiecke, René

2006-10-06

The tomato kinase Pto confers resistance to bacterial speck disease caused by Pseudomonas syringae pv. tomato in a gene for gene manner. Upon recognition of specific avirulence factors the Pto kinase activates multiple signal transduction pathways culminating in induction of pathogen defense. The soluble cytoplasmic serine/threonine kinase Pti1 is one target of Pto phosphorylation and is involved in the hypersensitive response (HR) reaction. However, a clear role of Pti1 in plant pathogen resistance is uncertain. So far, no Pti1 homologues from monocotyledonous species have been studied. Here we report the identification and molecular analysis of four Pti1-like kinases from maize (ZmPti1a, -b, -c, -d). These kinase genes showed tissue-specific expression and their corresponding proteins were targeted to different cellular compartments. Sequence similarity, expression pattern and cellular localization of ZmPti1b suggested that this gene is a putative orthologue of Pti1 from tomato. In contrast, ZmPti1a was specifically expressed in pollen and sequestered to the plasma membrane, evidently owing to N-terminal modification by myristoylation and/or S-acylation. The ZmPti1a:GFP fusion protein was not evenly distributed at the pollen plasma membrane but accumulated as an annulus-like structure which co-localized with callose (1,3-beta-glucan) deposition. In addition, co-localization of ZmPti1a and callose was observed during stages of pollen mitosis I and pollen tube germination. Maize plants in which ZmPti1a expression was silenced by RNA interference (RNAi) produced pollen with decreased competitive ability. Hence, our data provide evidence that ZmPti1a plays an important part in a signalling pathway that accelerates pollen performance and male fitness. ZmPti1a from maize is involved in pollen-specific processes during the progamic phase of reproduction, probably in crucial signalling processes associated with regions of callose deposition. Pollen

Effects of pollen dilution on infection of Nosema ceranae in honey bees.

Science.gov (United States)

Jack, Cameron J; Uppala, Sai Sree; Lucas, Hannah M; Sagili, Ramesh R

2016-04-01

Multiple stressors are currently threatening honey bee health, including pests and pathogens. Among honey bee pathogens, Nosema ceranae is a microsporidian found parasitizing the western honey bee (Apis mellifera) relatively recently. Honey bee colonies are fed pollen or protein substitute during pollen dearth to boost colony growth and immunity against pests and pathogens. Here we hypothesize that N. ceranae intensity and prevalence will be low in bees receiving high pollen diets, and that honey bees on high pollen diets will have higher survival and/or increased longevity. To test this hypothesis we examined the effects of different quantities of pollen on (a) the intensity and prevalence of N. ceranae and (b) longevity and nutritional physiology of bees inoculated with N. ceranae. Significantly higher spore intensities were observed in treatments that received higher pollen quantities (1:0 and 1:1 pollen:cellulose) when compared to treatments that received relatively lower pollen quantities. There were no significant differences in N. ceranae prevalence among different pollen diet treatments. Interestingly, the bees in higher pollen quantity treatments also had significantly higher survival despite higher intensities of N. ceranae. Significantly higher hypopharyngeal gland protein was observed in the control (no Nosema infection, and receiving a diet of 1:0 pollen:cellulose), followed by 1:0 pollen:cellulose treatment that was inoculated with N. ceranae. Here we demonstrate that diet with higher pollen quantity increases N. ceranae intensity, but also enhances the survival or longevity of honey bees. The information from this study could potentially help beekeepers formulate appropriate protein feeding regimens for their colonies to mitigate N. ceranae problems. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

100 GHz, 1 MW, CW gyrotron study program. Final report

International Nuclear Information System (INIS)

Felch, K.; Bier, R.; Caplan, M.; Jory, H.

1983-09-01

The results of a study program to investigate the feasibility of various approaches in designing a 100 GHz, 1 MW CW gyrotron are presented. A summary is given of the possible configurations for a high average power, high frequency gyrotron, including an historical survey of experimental results which are relevant to the various approaches. A set of basic scaling considerations which enable qualitative comparisons between particular gyrotron interaction circuits is presented. These calculations are important in understanding the role of various electron beam and circuit parameters in achieving a viable gyrotron design. Following these scaling exercises, a series of design calculations is presented for a possible approach in achieving 100 GHz, 1 MW CW. These calculations include analyses of the electron gun and interaction circuit parts of the gyrotron, and a general analysis of other aspects of a high average power, high frequency gyrotron. Scalability of important aspects of the design to other frequencies is also discussed, as well as key technology issues

Investigating Pollen and Gene Flow of WYMV-Resistant Transgenic Wheat N12-1 Using a Dwarf Male-Sterile Line as the Pollen Receptor.

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Dong, Shanshan; Liu, Yan; Yu, Cigang; Zhang, Zhenhua; Chen, Ming; Wang, Changyong

2016-01-01

Pollen-mediated gene flow (PMGF) is the main mode of transgene flow in flowering plants. The study of pollen and gene flow of transgenic wheat can help to establish the corresponding strategy for preventing transgene escape and contamination between compatible genotypes in wheat. To investigate the pollen dispersal and gene flow frequency in various directions and distances around the pollen source and detect the association between frequency of transgene flow and pollen density from transgenic wheat, a concentric circle design was adopted to conduct a field experiment using transgenic wheat with resistance to wheat yellow mosaic virus (WYMV) as the pollen donor and dwarf male-sterile wheat as the pollen receptor. The results showed that the pollen and gene flow of transgenic wheat varied significantly among the different compass sectors. A higher pollen density and gene flow frequency was observed in the downwind SW and W sectors, with average frequencies of transgene flow of 26.37 and 23.69% respectively. The pollen and gene flow of transgenic wheat declined dramatically with increasing distance from its source. Most of the pollen grains concentrated within 5 m and only a few pollen grains were detected beyond 30 m. The percentage of transgene flow was the highest where adjacent to the pollen source, with an average of 48.24% for all eight compass directions at 0 m distance. Transgene flow was reduced to 50% and 95% between 1.61 to 3.15 m, and 10.71 to 20.93 m, respectively. Our results suggest that climate conditions, especially wind direction, may significantly affect pollen dispersal and gene flow of wheat. The isolation-by-distance model is one of the most effective methods for achieving stringent transgene confinement in wheat. The frequency of transgene flow is directly correlated with the relative density of GM pollen grains in air currents, and pollen competition may be a major factor influencing transgene flow.

Investigating Pollen and Gene Flow of WYMV-Resistant Transgenic Wheat N12-1 Using a Dwarf Male-Sterile Line as the Pollen Receptor.

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Shanshan Dong

Full Text Available Pollen-mediated gene flow (PMGF is the main mode of transgene flow in flowering plants. The study of pollen and gene flow of transgenic wheat can help to establish the corresponding strategy for preventing transgene escape and contamination between compatible genotypes in wheat. To investigate the pollen dispersal and gene flow frequency in various directions and distances around the pollen source and detect the association between frequency of transgene flow and pollen density from transgenic wheat, a concentric circle design was adopted to conduct a field experiment using transgenic wheat with resistance to wheat yellow mosaic virus (WYMV as the pollen donor and dwarf male-sterile wheat as the pollen receptor. The results showed that the pollen and gene flow of transgenic wheat varied significantly among the different compass sectors. A higher pollen density and gene flow frequency was observed in the downwind SW and W sectors, with average frequencies of transgene flow of 26.37 and 23.69% respectively. The pollen and gene flow of transgenic wheat declined dramatically with increasing distance from its source. Most of the pollen grains concentrated within 5 m and only a few pollen grains were detected beyond 30 m. The percentage of transgene flow was the highest where adjacent to the pollen source, with an average of 48.24% for all eight compass directions at 0 m distance. Transgene flow was reduced to 50% and 95% between 1.61 to 3.15 m, and 10.71 to 20.93 m, respectively. Our results suggest that climate conditions, especially wind direction, may significantly affect pollen dispersal and gene flow of wheat. The isolation-by-distance model is one of the most effective methods for achieving stringent transgene confinement in wheat. The frequency of transgene flow is directly correlated with the relative density of GM pollen grains in air currents, and pollen competition may be a major factor influencing transgene flow.

Effects of gamma irradiation of pollen on parthenogenetic haploid production in muskmelon (Cucumis melo L.)

International Nuclear Information System (INIS)

Cuny, F.; Grotte, M.; Dumas de Vaulx, R.; Rieu, A.

1993-01-01

The effects of increasing gamma ray exposures on muskmelon pollen of the Védrantais genotype were evaluated after autofertilization and hybridization with the F1.G1 genotype. Regardless of doses of between 0.15 and 1.6 kGy, fruit set and number of seeds per fruit were comparable to those of the control. The pollen tube from pollen irradiated with up to 2.5 kGy grew in styles and reached the ovules. When pollen was cultivated in vitro, relatively high doses of irradiation (1.6 kGy) were needed to reduce the level of germination. Radiation-induced changes in the generative nucleus led to the formation of two chromosomally unbalanced sperm cells (as indicated by the appearance of morphological dimorphism) which induced parthenogenetic development of the egg to form a haploid embryo. Haploid embryo production by gamma-irradiated pollen was genotype dependent. For exposures of between 0.15 and 2.5 kGy, the production of embryos was the same, about 3.4%; a maximum of 70% of these embryos placed in a specific culture medium produced haploid plants. The ploidy of the plantlets in vitro was determined by flow cytometry. No aneuploidy was detected. All resulting plants exhibited normal phenotypes. (author) [fr

Cucumber (Cucumis sativus L.) embryo development in situ after pollination with irradiated pollen

International Nuclear Information System (INIS)

Faris, N.M.; Niemirowicz-Szczytt, K.

1999-01-01

Embryological studies were undertaken to compare the normal development of cucumber endosperm and embryo with that observed after pollination with gamma-irradiated pollen (0.1 and 0.3 kGy). Delayed penetration of the pollen tube occurred at both irradiation doses. Endosperm and embryo development was also delayed, but was initiated within 6 days after pollination in 100% of embryo sacs at 0.1 kGy and in 70-80% at 0.3 kGy. Various abnormalities in endosperm and embryo cell structure confirmed progressive degeneration, which occurred earlier with the higher dose of irradiation. Degeneration increased dramatically; only 30-40% of the embryos reached the globular stage 15 days after pollination. (author)

Proteomic analysis of MG132-treated germinating pollen reveals expression signatures associated with proteasome inhibition.

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Candida Vannini

Full Text Available Chemical inhibition of the proteasome has been previously found to effectively impair pollen germination and tube growth in vitro. However, the mediators of these effects at the molecular level are unknown. By performing 2DE proteomic analysis, 24 differentially expressed protein spots, representing 14 unique candidate proteins, were identified in the pollen of kiwifruit (Actinidia deliciosa germinated in the presence of the MG132 proteasome inhibitor. qPCR analysis revealed that 11 of these proteins are not up-regulated at the mRNA level, but are most likely stabilized by proteasome inhibition. These differentially expressed proteins are predicted to function in various pathways including energy and lipid metabolism, cell wall synthesis, protein synthesis/degradation and stress responses. In line with this evidence, the MG132-induced changes in the proteome were accompanied by an increase in ATP and ROS content and by an alteration in fatty acid composition.

Irradiation creep and growth of zircaloy-4 tubes

International Nuclear Information System (INIS)

Lansiart, S.; Darchis, L.; Pelchat, J.

1990-01-01

The influence of temperature and fast neutron flux on irradiation creep and growth of stress relieved zircaloy-4 pressurized tubes has been derived from experimental irradiations in NaK, performed up to 2.5 10 25 n.m -2 in the temperature range [280, 350] 0 C. A significant influence of temperature on axial growth has been observed: at 280 0 C the elongation can no longer be expressed as a linear function of fluence as for the 350 0 C irradiation temperature; diametral growth, on the other hand, always appears negligible. Irradiation creep obviously depends on temperature too; the diametral strain (including thermal part) has been modelled as a sum of primary and secondary terms, the former being independent of fluence. For the tubing considered it is observed that the ranking of the different batches, with respect to diametral creep resistance, is the same before and under irradiation. Concerning axial creep strain the stress relieved material behaves as does an isotropic tube. This is not the case of recrystallized zircaloy-4 F, which shows a non negligible axial deformation, related to the diametral creep one, even though this diametral irradiation creep strain is strongly reduced comparatively to that of the stress relieved material. The comparison of the two materials growth rates is more complex since their dependence on temperature and flux differs

The PTI1-like kinase ZmPti1a from maize (Zea mays L. co-localizes with callose at the plasma membrane of pollen and facilitates a competitive advantage to the male gametophyte

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Wienand Udo

2006-10-01

Full Text Available Abstract Background The tomato kinase Pto confers resistance to bacterial speck disease caused by Pseudomonas syringae pv. tomato in a gene for gene manner. Upon recognition of specific avirulence factors the Pto kinase activates multiple signal transduction pathways culminating in induction of pathogen defense. The soluble cytoplasmic serine/threonine kinase Pti1 is one target of Pto phosphorylation and is involved in the hypersensitive response (HR reaction. However, a clear role of Pti1 in plant pathogen resistance is uncertain. So far, no Pti1 homologues from monocotyledonous species have been studied. Results Here we report the identification and molecular analysis of four Pti1-like kinases from maize (ZmPti1a, -b, -c, -d. These kinase genes showed tissue-specific expression and their corresponding proteins were targeted to different cellular compartments. Sequence similarity, expression pattern and cellular localization of ZmPti1b suggested that this gene is a putative orthologue of Pti1 from tomato. In contrast, ZmPti1a was specifically expressed in pollen and sequestered to the plasma membrane, evidently owing to N-terminal modification by myristoylation and/or S-acylation. The ZmPti1a:GFP fusion protein was not evenly distributed at the pollen plasma membrane but accumulated as an annulus-like structure which co-localized with callose (1,3-β-glucan deposition. In addition, co-localization of ZmPti1a and callose was observed during stages of pollen mitosis I and pollen tube germination. Maize plants in which ZmPti1a expression was silenced by RNA interference (RNAi produced pollen with decreased competitive ability. Hence, our data provide evidence that ZmPti1a plays an important part in a signalling pathway that accelerates pollen performance and male fitness. Conclusion ZmPti1a from maize is involved in pollen-specific processes during the progamic phase of reproduction, probably in crucial signalling processes associated with regions

Effects of Royal Jelly and Bee Pollen on the Growth of Selected Probiotic Bacteria (Bf. animalis Spp. Lactis, L. acidophilus and L. casei

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Guldas Metin

2016-12-01

Full Text Available In this research article, the effects of bee pollen and royal jelly on the selected probiotic bacteria, as growth factors, were investigated. The probiotic cultures were activated in MRS broth at 37°C. Then, bee pollen and royal jelly (10 mg/100 μL, 25 mg/250 μL, 50 mg/500 μL, 75 mg/750 μL, and 100 mg/1000 μL were added on the probiotic cultures in MRS broth and sampled at 0, 24, and 48 hours of incubation. The medias used for enumeration of the probiotic cultures were RCA (Reinforced Clostridial Agar for Bf. animalis spp. lactis, MRS (deMann, Rogosa and Sharpe Agar with D-sorbitol for Lb. acidophilus and MRS-Vancomycine Agar for Lb. casei. The lactic acid production by Lb. acidophilus, Lb. casei, and Bf. animalis spp. lactis, and acetic acid production by Bf. animalis spp. lactis, were determined to compare the bacterial proliferation. The probiotic cultures were mainly affected by the bee pollen and royal jelly during the first 24 hours. The changes observed in the number of probiotic counts between 24 and 48 hours were not significant, statistically (P<0.05. Generally, the probiotic bacterial counts increased parallel to the concentration of bee pollen or royal jelly up to 75mg, and remained unchanged above this concentration. In terms of lactic acid production and bacterial growth, the most significant growth was observed on Lb. acidophilus when bee pollen or royal jelly was added.

Polyploidy Enhances F1 Pollen Sterility Loci Interactions That Increase Meiosis Abnormalities and Pollen Sterility in Autotetraploid Rice.

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Wu, Jinwen; Shahid, Muhammad Qasim; Chen, Lin; Chen, Zhixiong; Wang, Lan; Liu, Xiangdong; Lu, Yonggen

2015-12-01

Intersubspecific autotetraploid rice (Oryza sativa ssp. indica × japonica) hybrids have greater biological and yield potentials than diploid rice. However, the low fertility of intersubspecific autotetraploid hybrids, which is largely caused by high pollen abortion rates, limits their commercial utility. To decipher the cytological and molecular mechanisms underlying allelic interactions in autotetraploid rice, we developed an autotetraploid rice hybrid that was heterozygous (S(i)S(j)) at F1 pollen sterility loci (Sa, Sb, and Sc) using near-isogenic lines. Cytological studies showed that the autotetraploid had higher percentages (>30%) of abnormal chromosome behavior and aberrant meiocytes (>50%) during meiosis than did the diploid rice hybrid control. Analysis of gene expression profiles revealed 1,888 genes that were differentially expressed between the autotetraploid and diploid hybrid lines at the meiotic stage, among which 889 and 999 were up- and down-regulated, respectively. Of the 999 down-regulated genes, 940 were associated with the combined effect of polyploidy and pollen sterility loci interactions (IPE). Gene Ontology enrichment analysis identified a prominent functional gene class consisting of seven genes related to photosystem I (Gene Ontology 0009522). Moreover, 55 meiosis-related or meiosis stage-specific genes were associated with IPE in autotetraploid rice, including Os02g0497500, which encodes a DNA repair-recombination protein, and Os02g0490000, which encodes a component of the ubiquitin-proteasome pathway. These results suggest that polyploidy enhances epistatic interactions between alleles of pollen sterility loci, thereby altering the expression profiles of important meiosis-related or meiosis stage-specific genes and resulting in high pollen sterility. © 2015 American Society of Plant Biologists. All Rights Reserved.

Sweet attraction: sugarcane pollen-associated volatiles attract gravid Anopheles arabiensis.

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Wondwosen, Betelehem; Birgersson, Göran; Tekie, Habte; Torto, Baldwyn; Ignell, Rickard; Hill, Sharon R

2018-02-21

Anopheles arabiensis is a key vector for the transmission of human malaria in sub-Saharan Africa. Over the past 10,000 years, humans have successfully cultivated grasses and altered the landscape, creating An. arabiensis favourable environments that contain excellent habitats for both larvae and adults. Sugarcane is the most expanding agricultural system in sub-Saharan Africa, and is linked to the increased threat of malaria in rural communities. The prolific production and wind dispersal of sugarcane pollen, together with standing pools of water, often provide, as a result of irrigation, a nutrient-rich environment for the offspring of gravid malaria mosquitoes. In the present study, sugarcane pollen-associated volatiles from two cultivars are shown to attract gravid An. arabiensis in a still air two-port olfactometer and stimulate egg laying in an oviposition bioassay. Through combined gas chromatography and electroantennographic detection, as well as combined gas chromatography and mass spectrometric analyses, we identified the bioactive volatiles and generated a synthetic blend that reproduced the full behavioural repertoire of gravid mosquitoes in the Y-tube assay. Two subtractive odour blends, when compared with the full blend, were significantly more attractive. These three and four-component subtractive blends share the compounds (1R)-(+)-α-pinene, nonanal and benzaldehyde, of which, (1R)-(+)-α-pinene and nonanal are found in the attractive odour blends from rice plants and maize pollen. In pairwise comparisons, the rice synthetic odour blend was more attractive to gravid mosquitoes than either of the pollen blends, whereas the pollen blends did not differ in attraction. The attraction of gravid females to sugarcane pollen volatiles demonstrated in this study, together with the previously found grass-associated volatiles, raise the potential of developing a bioactive chimeric blend to attract gravid malaria mosquitoes. This is discussed in relation to

In vitro germination and viability of pollen grain of coconut accessions1

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Catrine Regina Feitosa Moura

Full Text Available Storage as a means of maintaining the pollen viability is important for the preservation of the genetic variability, facilitates the exchange of germplasm and greatly contributes to the generation of variability obtained from artificial crosses, increasing the efficiency of breeding programs. The objective of this study was to select different culture media for the in vitro germination of pollen grain of dwarf and tall coconut accessions, as well as to determine the viability of pollen grain at room temperature conditions. For this purpose, Brazil Green Dwarf (BGD and Brazilian Tall (BRA pollen grains derived from the Coconut Active Germplasm Bank of Embrapa Coastal Tablelands Sergipe were used. To evaluate the effect of different culture media on the in vitro germination of pollen grains of anão verde do Brasil de Jiqui (AVeBrJ and gigante do Brasil Praia do Forte (GBrPF accessions, they were inoculated on to Petri dishes containing 2 ml of culture media. The pollen viability was assessed by staining with 1% acetic carmine and in vitro germination at 0, 24, 48 and 72 hours. The culture medium of Lora is suitable to assess the in vitrogermination of pollen grain of the AVeBrJ and GBrPF accessions. The pollen grain of the AVeBrJ accession showed intermediate viability (66.87% at room temperature up to 23.14 hours by in vitro germination. The pollen grain of the GBrPF accession showed high viability, above 70%, at room temperature up to 120 hours by in vitro germination.

Pollen-Associated Microbiome Correlates with Pollution Parameters and the Allergenicity of Pollen.

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Andrea Obersteiner

Full Text Available Pollen allergies have been rapidly increasing over the last decades. Many allergenic proteins and non-allergenic adjuvant compounds of pollen are involved in the plant defense against environmental or microbial stress. The first aim of this study was to analyze and compare the colonizing microbes on allergenic pollen. The second aim was to investigate detectable correlations between pollen microbiota and parameters of air pollution or pollen allergenicity. To reach these aims, bacterial and fungal DNA was isolated from pollen samples of timothy grass (Phleum pratense, n = 20 and birch trees (Betula pendula, n = 55. With this isolated DNA, a terminal restriction fragment length polymorphism analysis was performed. One result was that the microbial diversity on birch tree and timothy grass pollen samples (Shannon/Simpson diversity indices was partly significantly correlated to allergenicity parameters (Bet v 1/Phl p 5, pollen-associated lipid mediators. Furthermore, the microbial diversity on birch pollen samples was correlated to on-site air pollution (nitrogen dioxide (NO2, ammonia (NH3, and ozone (O3. What is more, a significant negative correlation was observed between the microbial diversity on birch pollen and the measured NO2 concentrations on the corresponding trees. Our results showed that the microbial composition of pollen was correlated to environmental exposure parameters alongside with a differential expression of allergen and pollen-associated lipid mediators. This might translate into altered allergenicity of pollen due to environmental and microbial stress.

Sulfinylated Azadecalins act as functional mimics of a pollen germination stimulant in Arabidopsis pistils

Science.gov (United States)

Qin, Yuan; Wysocki, Ronald J; Somogyi, Arpad; Feinstein, Yelena; Franco, Jessica Y; Tsukamoto, Tatsuya; Dunatunga, Damayanthi; Levy, Clara; Smith, Steven; Simpson, Robert; Gang, David; Johnson, Mark A; Palanivelu, Ravishankar

2011-01-01

SUMMARY Polarized cell elongation is triggered by small molecule cues during development of diverse organisms. During plant reproduction, pollen interactions with the stigma result in the polar outgrowth of a pollen tube, which delivers sperm cells to the female gametophyte to effect double fertilization. In many plants, pistils stimulate pollen germination. However, in Arabidopsis, the effect of pistils on pollen germination and the pistil factors that stimulate pollen germination remain poorly characterized. Here, we demonstrate that stigma, style, and ovules in Arabidopsis pistils stimulate pollen germination. We isolated an Arabidopsis pistil extract fraction that stimulates Arabidopsis pollen germination, and employed ultrahigh resolution ESI FT-ICR and MS/MS techniques to accurately determine the mass (202.126 daltons) of a compound that is specifically present in this pistil extract fraction. Using the molecular formula (C10H19NOS) and tandem mass spectral fragmentation patterns of the m/z (mass to charge ratio) 202.126 ion, we postulated chemical structures, devised protocols, synthesized N-Methanesulfinyl 1- and 2-azadecalins that are close structural mimics of the m/z 202.126 ion, and showed that they are sufficient to stimulate Arabidopsis pollen germination in vitro (30 µM stimulated ~50% germination) and elicit accession-specific response. Although N-Methanesulfinyl 2-azadecalin stimulated pollen germination in three species of Lineage I of Brassicaceae, it did not induce a germination response in Sisymbrium irio (Lineage II of Brassicaceae) and tobacco, indicating that activity of the compound is not random. Our results show that Arabidopsis pistils promote germination by producing azadecalin-like molecules to ensure rapid fertilization by the appropriate pollen. PMID:21801250

Pollen-pistil interactions in North American and Chinese Cypripedium L. (Orchidaceae)

Science.gov (United States)

Retha Edens-Meier; Nan Vance; Yi-Bo Luo; Peng Li; Eric Westhus; Peter. Bernhardt

2010-01-01

Fluorescence microscopy is used to compare frequencies of pollen tube penetration in in situ populations of Cypripedium bardolphianumW.W. Smith et Farrer, Cypripedium flavum W.W. Smith, Cypripedium montanum Dougl. ex Lindl., Cypripedium parviflorum Salisbury var. pubescens...

In Vitro Pollen Viability and Pollen Germination in Cherry Laurel (Prunus laurocerasus L.

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Melekber Sulusoglu

2014-01-01

Full Text Available Pollen quality is important for growers and breeders. This study was carried out to determine in vitro pollen viability and pollen germination in seven genotypes of cherry laurel (Prunus laurocerasus L.. Two pollen viability tests, TTC (2,3,5-triphenyl tetrazolium chloride and IKI (iodine potassium iodide, were used. Pollen traits of genotypes were studied using an in vitro medium containing 0%, 5%, 10%, 15%, and 20% sucrose to determine the best sucrose concentrations for germination. In the second step, the germinated pollen was counted 1, 4, 6, 10, 12, 24, and 48 hours later until there was no further germination. The viability rates were different according to genotypes and tests used. The IKI and TTC staining tests and pollen germination had low correlation (r2 = 0.0614 and r2 = 0.0015, resp.. Painted pollen rate was higher and pollen was well-stained with IKI test and pollen viability estimated with TTC staining test was better than that estimated with the IKI staining test. 15% sucrose gave the best germination rates in most of the genotypes. Pollen germination rates were recorded periodically from one hour to 48 hours in 15% sucrose and the results showed that pollen germination rates increased after 6 hours of being placed in culture media.

In vitro pollen viability and pollen germination in cherry laurel (Prunus laurocerasus L.).

Science.gov (United States)

Sulusoglu, Melekber; Cavusoglu, Aysun

2014-01-01

Pollen quality is important for growers and breeders. This study was carried out to determine in vitro pollen viability and pollen germination in seven genotypes of cherry laurel (Prunus laurocerasus L.). Two pollen viability tests, TTC (2,3,5-triphenyl tetrazolium chloride) and IKI (iodine potassium iodide), were used. Pollen traits of genotypes were studied using an in vitro medium containing 0%, 5%, 10%, 15%, and 20% sucrose to determine the best sucrose concentrations for germination. In the second step, the germinated pollen was counted 1, 4, 6, 10, 12, 24, and 48 hours later until there was no further germination. The viability rates were different according to genotypes and tests used. The IKI and TTC staining tests and pollen germination had low correlation (r(2) = 0.0614 and r(2) = 0.0015, resp.). Painted pollen rate was higher and pollen was well-stained with IKI test and pollen viability estimated with TTC staining test was better than that estimated with the IKI staining test. 15% sucrose gave the best germination rates in most of the genotypes. Pollen germination rates were recorded periodically from one hour to 48 hours in 15% sucrose and the results showed that pollen germination rates increased after 6 hours of being placed in culture media.

Higher Temperature at Lower Elevation Sites Fails to Promote Acclimation or Adaptation to Heat Stress During Pollen Germination

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Lluvia Flores-Rentería

2018-04-01

Full Text Available High temperatures associated with climate change are expected to be detrimental for aspects of plant reproduction, such as pollen viability. We hypothesized that (1 higher peak temperatures predicted with climate change would have a minimal effect on pollen viability, while high temperatures during pollen germination would negatively affect pollen viability, (2 high temperatures during pollen dispersal would facilitate acclimation to high temperatures during pollen germination, and (3 pollen from populations at sites with warmer average temperatures would be better adapted to high temperature peaks. We tested these hypotheses in Pinus edulis, a species with demonstrated sensitivity to climate change, using populations along an elevational gradient. We tested for acclimation to high temperatures by measuring pollen viability during dispersal and germination stages in pollen subjected to 30, 35, and 40°C in a factorial design. We also characterized pollen phenology and measured pollen heat tolerance using trees from nine sites along a 200 m elevational gradient that varied 4°C in temperature. We demonstrated that this gradient is biologically meaningful by evaluating variation in vegetation composition and P. edulis performance. Male reproduction was negatively affected by high temperatures, with stronger effects during pollen germination than pollen dispersal. Populations along the elevational gradient varied in pollen phenology, vegetation composition, plant water stress, nutrient availability, and plant growth. In contrast to our hypothesis, pollen viability was highest in pinyons from mid-elevation sites rather than from lower elevation sites. We found no evidence of acclimation or adaptation of pollen to high temperatures. Maximal plant performance as measured by growth did not occur at the same elevation as maximal pollen viability. These results indicate that periods of high temperature negatively affected sexual reproduction, such that

Protein Profiling Reveals Novel Proteins in Pollen and Pistil of W22 (ga1; Ga1 in Maize

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Jin Yu

2014-05-01

Full Text Available Gametophytic factors mediate pollen-pistil interactions in maize (Zea mays L. and play active roles in limiting gene flow among maize populations and between maize and teosinte. This study was carried out to identify proteins and investigate the mechanism of gametophytic factors using protein analysis. W22 (ga1; which did not carry a gametophytic factor and W22 (Ga1, a near iso-genic line, were used for the proteome investigation. SDS-PAGE was executed to investigate proteins in the pollen and pistil of W22 (ga1 and W22 (Ga1. A total of 44 differentially expressed proteins were identified in the pollen and pistil on SDS-PAGE using LTQ-FTICR MS. Among the 44 proteins, a total of 24 proteins were identified in the pollen of W22 (ga1 and W22 (Ga1 whereas 20 differentially expressed proteins were identified from the pistil of W22 (ga1 and W22 (Ga1. However, in pollen, 2 proteins were identified only in the W22 (ga1 and 12 proteins only in the W22 (Ga1 whereas 10 proteins were confirmed from the both of W22 (ga1 and W22 (Ga1. In contrary, 10 proteins were appeared only in the pistil of W22 (ga1 and 7 proteins from W22 (Ga1 while 3 proteins confirmed in the both of W22 (ga1 and W22 (Ga1. Moreover, the identified proteins were generally involved in hydrolase activity, nucleic acid binding and nucleotide binding. These results help to reveal the mechanism of gametophytic factors and provide a valuable clue for the pollen and pistil research in maize.

Radioprotective effect of the pollen

International Nuclear Information System (INIS)

Jiang Ying; Zhu Gengbo; Huang Meiying; Yin Zhiwei; Fang Jixi; Fan Xiudi

1990-10-01

The radioprotective injury effect of pollen in animals was studied. Research came to the conclusion that: (1) the acute death rate of animals is decreased by the pollen; (2) the peripheral leukocytes and spleen-B-lymph cells of animals are increased by the pollen; (3) the activity of superoxide dimutase (SOD) in the erythrocytes of animals is increased by the pollen; (4) the pollen has the function of protecting the structure of the organs of thymus and testes and so on; (5) the plasma hydroxyproline of animals is remarkably decreased by the pollen

1 CW green self-frequency-doubled Yb:YAl3(BO3)4 laser

International Nuclear Information System (INIS)

Dekker, P.; Dawes, J.; Wang, P.; Piper, J.

2000-01-01

Full text: We report 1.1 W continuous wave (CW) green output from a 977nm diode-end-pumped self-frequency-doubled Yb:YAB laser, with a diode-to-green optical conversion efficiency of 10%. Wavelength tunability from 513-546nm has been demonstrated

3 μm CW lasers for myringotomy and microsurgery.

Science.gov (United States)

Linden, Kurt J; Pfeffer, Christian P; Sousa, John Gary; D'Alleva, Nicholas; Aslani, Arash; Gorski, Grzegorz; Kenna, Margaret; Poe, Dennis S

2013-03-08

This paper describes the development and implementation of 3 μm lasers for myringotomy and microsurgery. Two different lasers were investigated. The first, an Er-doped, CW zirconate glass fiber laser optically pumped by a 970 nm diode laser, emitted > 1 W of CW power at 2.76 μm with concomitant green incoherent emission that served as a convenient visible illumination beam. The second, a 1 W CW Er:YAG solid-state laser also optically pumped by a 970 nm diode laser, emitted > 1 W of CW power at 2.94 μm, coincident with the strongest infrared water absorption peak. Running CW, both lasers are expected to avoid the loud acoustical shocks associated with pulsed lasers. Myringotomies were carried out with the Er:YAG laser on anaesthetized guinea pigs and the effects of the laser were documented. Laser ablated samples of tympanic membrane, soft tissue and bone were histologically examined. Histology results indicated that the CW Er:YAG laser is a potential candidate for a new myringotomy tool and possibly for otologic microsurgery, but deliverable power levels need to be increased to the 2 W (or higher) level. This work was funded under NIH SBIR Grant No. 5R44DC004899.

Recombinant Mal d 1 facilitates sublingual challenge tests of birch pollen-allergic patients with apple allergy.

Science.gov (United States)

Kinaciyan, T; Nagl, B; Faustmann, S; Kopp, S; Wolkersdorfer, M; Bohle, B

2016-02-01

It is still unclear whether allergen-specific immunotherapy (AIT) with birch pollen improves birch pollen-related food allergy. One reason for this may be the lack of standardized tests to assess clinical reactions to birch pollen-related foods, for example apple. We tested the applicability of recombinant (r) Mal d 1, the Bet v 1-homolog in apple, for oral challenge tests. Increasing concentrations of rMal d 1 in 0.9% NaCl were sublingually administered to 72 birch pollen-allergic patients with apple allergy. The dose of 1.6 μg induced oral allergy syndromes in 26.4%, 3.2 μg in 15.3%, 6.3 μg in 27.8%, 12.5 μg in 8.3%, 25 μg in 11.1%, and 50 μg in 4.2% of the patients. No severe reactions occurred. None of the patients reacted to 0.9% NaCl alone. Sublingual administration of 50 μg of rMal d 1 induced no reactions in three nonallergic individuals. Our approach allows straight forward, dose-defined sublingual challenge tests in a high number of birch pollen-allergic patients that inter alia can be applied to evaluate the therapeutic efficacy of birch pollen AIT on birch pollen-related food allergy. © 2015 The Authors. Allergy Published by John Wiley & Sons Ltd.

Design of 250-MW CW RF system for APT

International Nuclear Information System (INIS)

Rees, D.

1997-01-01

The design for the RF systems for the APT (Accelerator Production of Tritium) proton linac will be presented. The linac produces a continuous beam power of 130 MW at 1300 MeV with the installed capability to produce up to a 170 MW beam at 1700 MeV. The linac is comprised of a 350 MHz RFQ to 7 MeV followed in sequence by a 700 MHz coupled-cavity drift tube linac, coupled-cavity linac, and superconducting (SC) linac to 1700 MeV. At the 1700 MeV, 100 mA level the linac requires 213 MW of continuous-wave (CW) RF power. This power will be supplied by klystrons with a nominal output power of 1.0 MW. 237 kystrons are required with all but three of these klystrons operating at 700 MHz. The klystron count includes redundancy provisions that will be described which allow the RF systems to meet an operational availability in excess of 95 percent. The approach to achieve this redundancy will be presented for both the normal conducting (NC) and SC accelerators. Because of the large amount of CW RF power required for the APT linac, efficiency is very important to minimize operating cost. Operation and the RF system design, including in-progress advanced technology developments which improve efficiency, will be discussed. RF system performance will also be predicted. Because of the simultaneous pressures to increase RF system reliability, reduce tunnel envelope, and minimize RF system cost, the design of the RF vacuum windows has become an important issue. The power from a klystron will be divided into four equal parts to minimize the stress on the RF vacuum windows. Even with this reduction, the RF power level at the window is at the upper boundary of the power levels employed at other CW accelerator facilities. The design of a 350 MHz, coaxial vacuum window will be presented as well as test results and high power conditioning profiles. The transmission of 950 kW, CW, power through this window has been demonstrated with only minimal high power conditioning

A comparison of pollen-siring ability and life history between males and hermaphrodites of subdioecious Silene acaulis

DEFF Research Database (Denmark)

Philipp, Marianne; Jakobsen, Ruth Bruus; Nachman, Gøsta Støger

2009-01-01

was performed in which females were hand A pollen-competition experiment was performed in which females were hand pollinated with a mixture of pollen from males and hermaphrodites, all with known isozyme alleles, which allowed determination of who sired each seed. We recorded plant size, flower morphology......, hermaphrodite, and male individuals. The sex expression of males and hermaphrodites can vary over years for the same individual, while females are always females. Previous studies have shown that outcrossed seeds from females become seedlings with higher survival and growth rates than those from outcrossed...... seeds from hermaphrodites.Questions: (1) Do pollen grains from males exhibit some advantage over pollen from (1) Do pollen grains from males exhibit some advantage over pollen from hermaphrodites? In particular, do they sire more seeds than hermaphrodites? (2) Is the reproductive system of S. acaulis...

Design of the 3.7 GHz, 500 kW CW circulator for the LHCD system of the SST-1 tokamak

Energy Technology Data Exchange (ETDEWEB)

Dixit, Harish V., E-mail: hvdixit48@yahoo.com [Veermata Jijabai Technological Institute, Mumbai, Maharashtra 400019 (India); Jadhav, Aviraj R. [Veermata Jijabai Technological Institute, Mumbai, Maharashtra 400019 (India); Jain, Yogesh M. [Institute for Plasma Research, Gandhinagar, Gujarat 382428 (India); Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094 (India); Cheeran, Alice N. [Veermata Jijabai Technological Institute, Mumbai, Maharashtra 400019 (India); Gupta, Vikas [Vidyavardhini' s College of Engineering and Technology, Vasai, Maharashtra 401202 (India); Sharma, P.K. [Institute for Plasma Research, Gandhinagar, Gujarat 382428 (India); Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094 (India)

2017-06-15

Highlights: • Design of a 500 kW CW circulator for LHCD system at 3.7 GHz. • Mechanism for thermal management of ferrite tile. • Scheme for uniform magnetisation of the ferrite tiles. • Design of high CW power CW quadrature and 180 ° hybrid coupler. - Abstract: Circulators are used in high power microwave systems to protect the vacuum source against reflection. The Lower Hybrid Current Drive (LHCD) system of SST-1 tokamak commissioned at IPR, Gandhinagar in India comprises of four high power circulators to protect klystrons (supplying 500 kW CW each at 3.7 GHz) which power the system. This paper presents the design of a Differential Phase Shift Circulator (DPSC) capable of handling 500 kW CW power at 3.7 GHz so that four circulators can be used to protect the four available klystrons. As the DPSC is composed by three main components, viz., magic tee, ferrite phase shifter and 3 dB hybrid coupler, the designing of each of the proposed components is described. The design of these components is carried out factoring various multiphysics aspects of RF, heating due to high CW power and magnetic field requirement of the ferrite phase shifter. The primary objective of this paper is to present the complete RF, magnetic and thermal design of a high CW power circulator. All the simulations have been carried out in COMSOL Multiphysics. The designed circulator exhibits an insertion loss of 0.13 dB with a worst case VSWR of 1.08:1. The total length of the circulator is 3 m.

Cw RFQ development

International Nuclear Information System (INIS)

Schriber, S.O.

1985-01-01

A review of research and development related to fabricating and operating radio-frequency quadrupole (RFQ) structures at 100% duty cycle [continuous wave (cw)] is presented, with emphasis on work at the Los Alamos National Laboratory, the Chalk River Nuclear Laboratories, and the University of Frankfurt. Activities in other areas that have an impact on operating cw RFQ systems will be highlighted. 27 refs

Emittance compensation of CW DC-gun photoinjector

International Nuclear Information System (INIS)

Li Peng; Wu Dai; Xu Zhou; Li Ming; Yang Xingfan

2011-01-01

Emittance growth induced by space charge effect is very important, especially for CW DC-gun photoinjector. In this work, the linear space charge force and its effect on electron beam transverse emittance are studied, and the principle and properties of emittance compensation by solenoid are analyzed. The CAEP DC-gun photoinjector with a solenoid is also simulated by code Parmela. Simulated results indicate that the normalized transverse emittance of an 80 pC bunch at the 350 keV DC-gun ex-it is 5.14 mm · mrad. And after compensated by a solenoid, it becomes 1.27 mm · mrad. The emittance of beam is well compensated. (authors)

Platanus pollen allergen, Pla a 1: quantification in the atmosphere and influence on a sensitizing population.

Science.gov (United States)

Fernández-González, D; González-Parrado, Z; Vega-Maray, A M; Valencia-Barrera, R M; Camazón-Izquierdo, B; De Nuntiis, P; Mandrioli, P

2010-11-01

The allergic response in susceptible patients does not always coincide with the presence and magnitude of airborne pollen counts. The prevalence of allergy to Platanus is currently moderate, although the percentage of monosensitized patients is low. This hinders accurate interpretation of the relationship between the amount of pollen inhaled and the patient's symptoms. This study aims to investigate the relationship between the atmospheric concentration pattern of Pla a 1 aeroallergen and the Platanus pollen. The pollen sampling was carried out using a Hirst-type volumetric trap (Burkard(©) ) for pollen grains and a Burkard Cyclone sampler (Burkard(©) ) for Pla a 1 allergen. Serum-specific IgE levels to Acer sp., Artemisia vulgaris, Betula alba, Chenopodium album, Cupressus arizonica, Cynodon dactylon, Fraxinus excelsior, Lolium perenne, Pinus sp., Plantago lanceolata, Platanus acerifolia, Populus sp., Quercus ilex and Taraxacum officinale allergens were determined using the EAST System (Hytec specific IgE EIA kit; Hycor Biomedical, Kassel, Germany). The aerobiological dynamics of Platanus pollen grains and Pla a 1 differed considerably, particularly during the Platanus pollination period. Of the 118 subjects tested, sera from 34 contained specific IgE to Platanus pollen and all of them had specific IgE to other pollen types. The presence of the aeroallergen Pla a 1 in the atmosphere appears to be independent of Platanus pollen counts over the same period, which may be contributing to allergic symptoms and sensitization. The number of polysensitized patients displaying allergy to Platanus suggested that allergic symptoms were caused by co-sensitization or cross-reactivity involving a number of allergenic particles. © 2010 Blackwell Publishing Ltd.

CW 3μm lasing via two-photon pumping in cesium vapor with a 1W source

Science.gov (United States)

Haluska, Nathan D.; Rice, Christopher A.; Perram, Glen P.

2018-02-01

We report the first CW lasing from two-photon pumping via a virtual state. Pulsed and the CW lasing of the 3096 nm 72 P1/2 to 72 S1/2 line are observed from degenerate two-photon pumping of the cesium 72 S1/2 to 62 D3/2 transition. High intensity pulses excite over 17 lasing wavelengths. Under lower intensity CW excitation, 3 μm lasing is still observed with efficiencies of 0.7%. CW experiments utilized a Cs heat pipe at 150 °C to 270 °C, and a highly-focused, single pass, Ti-Sapphire pump with no aid of a cavity. Unlike normal DPALS, this architecture does not require buffer gas, and heat is released optically so a flowing system is not required. Both suggest a very simple device with excellent beam quality is possible. This proof of concept can be greatly enhanced with more optimal conditions such as non-degenerate pumping to further increase the two-photon pump cross section and the addition of a cavity to improve mode volume overlap. These improvements may lead to an increase in efficiencies to a theoretical maximum of 14%. Results suggest two-photon pumping with diodes is feasible.

High correlation of specific IgE sensitization between birch pollen, soy and apple allergens indicates pollen-food allergy syndrome among birch pollen allergic patients in northern China.

Science.gov (United States)

Hao, Guo-Dong; Zheng, Yi-Wu; Wang, Zhi-Xiang; Kong, Xing-Ai; Song, Zhi-Jing; Lai, Xu-Xin; Spangfort, Michael D

2016-05-01

Birch pollen sensitization and associated pollen-food syndrome among Chinese allergic patients have not been investigated. Sera from 203 allergic patients from the northern part of China and collected during February to July 2014 were investigated. Specific immunoglobulin E (IgE) against birch pollen extract Bet v and major birch pollen allergen Bet v 1 were measured using the ADVIA Centaur. The presence of major apple allergen Mal d 1 and soy bean allergen Gly m 4 specific IgE was measured by ImmunoCAP 100. Among the 203 sera, 34 sera (16.7%) had specific IgE to Bet v and of these, 28 sera (82.4%) contained Bet v 1-specific IgE. Among the 28 sera with Bet v 1-specific IgE, 27 sera (96.4%) contained Mal d 1-specific IgE and 22 sera (78.6%) contained Gly m 4-specific IgE. Of the 34 Bet v-positive sera, 6 sera (17.6%) contained no specific IgE for Bet v 1, Mal d 1, or Gly m 4. Almost all Bet v-positive sera were donated during the birch pollen season. The prevalence of birch allergy among patients visiting health care during pollen season can be as high as 16.7% in Tangshan City. The majority of Chinese birch allergic patients are IgE-sensitized to the major birch pollen allergen Bet v 1 as well as to the major apple allergen Mal d 1 and soy bean allergen Gly m 4. A relatively high number of patients (17.6%) are IgE-sensitized to birch pollen allergen(s) other than Bet v 1. The high prevalence of specific IgE to Mal d 1 and Gly m 4 among Bet v 1-sensitized patients indicates that pollen-food allergy syndrome could be of clinical relevance in China.

Effect of Pollen Feed on Parasitization and Predatism of Cephalonomia stephanoderis onHypothenemus hampei

Directory of Open Access Journals (Sweden)

Dwi Suci Rahayu

2014-05-01

Full Text Available Biological control of the coffee berry borer (Hypothenemus hampeiusing parasitoid Cephalonomia stephanoderishas been developed through the improvement of the parasitoid role may using pollens as feed source. The objective of this study was to investigate the effect of cover crop and weed pollens on parasitization and predatism of C. stephanoderis.The applied treatments were pollens of Turnera ulmifolia, Arachis pintoi, Ageratum conyzoidesadded in glass tube that consist of 10 CBB pupaes and a mated female of C. stephanoderis. Number of pupae parasitized and pupae preyed were observed. The result showed that addition of A. Pintoi pollen increased the number of pupae parasitized at 135% whereas addition of T. ulmifolia and A. conyzoides pollens did not affect parasitization of C. Stephanoderis. The predatismof C. stephanoderiswas higher than parasitization to pupae of H. hampei which showed that the behavior of C. stephanoderiswas parasitization. Addition of T. ulmifolia, A. pintoi, and A. conyzoidespollens increased the number of pupae predatism at 132%, 102%, and 225%, respectively. Key words: Ageratum conyzoides, Arachis pintoi, Cephalonomia stephanoderis, Hypothenemus hampei,parasitization, predatism, pollens, Turnera ulmifolia

Status of the bench-test system for the tubes in the HIMAC DTL linac

International Nuclear Information System (INIS)

Fujimoto, T.; Ishikawa, S.; Kobayashi, C.

2000-01-01

The tetrode tube of SIEMENS RS2074SK is used for HIMAC DTL (Drift Tube Linac) 1.4 MW final amplifiers. We installed a bench-test system for this tube in 1999. This system can be used under low power operation with CW mainly for filament aging. This system consists of DC sources, drive-amplifier (5 kW transistor amplifier) and 3/4λ coaxial input and output circuits. We will also use this system to improve the DTL final amplifiers, for example to reduce the parasitic oscillation level. This paper describes status of this system. (author)

PECTATE LYASE-LIKE10 is associated with pollen wall development in Brassica campestris.

Science.gov (United States)

Jiang, Jingjing; Yao, Lina; Yu, Youjian; Lv, Meiling; Miao, Ying; Cao, Jiashu

2014-11-01

PECTATE LYASE-LIKE10 (PLL10) was previously identified as one of the differentially expressed genes both in microspores during the late pollen developmental stages and in pistils during the fertilization process in Chinese cabbage (Brassica campestris ssp. chinensis). Here, antisense-RNA was used to study the functions of BcPLL10 in Chinese cabbage. Abnormal pollen was identified in the transgenic lines (bcpll10-4, -5, and -6). In fertilization experiments, fewer seeds were harvested when the antisense-RNA lines were used as pollen donor. In vivo and in vitro pollen germination assays less germinated pollen tubes were observed in bcpll10 lines. Scanning electron microscopy observation verified that the tryphine materials were over accumulated around the pollen surface and sticked them together in bcpll10. Moreover, transmission electron microscopy observation revealed that the internal endintine was overdeveloped and predominantly occupied the intine, and disturbed the normal proportional distribution of the two layers in the non-germinal furrow region; and no obvious demarcation existed between them in the germinal furrow region in the bcpll10 pollen. Collectively, this study presented a novel PLL gene that played an important role during the pollen wall development in B. campestris, which may also possess potential importance for male sterility usage in agriculture. © 2014 Institute of Botany, Chinese Academy of Sciences.

CW operation of high-power blue laser diodes with polished facets on semi-polar ( 20 2 ¯ 1 ¯ ) GaN substrates

KAUST Repository

Pourhashemi, A.

2016-10-11

Continuous wave (CW) operation of high-power blue laser diodes (LDs) with polished facets on semi-polar (202̅1̅) gallium nitride (GaN) substrates is demonstrated. Ridge waveguide LDs were fabricated using indium GaN waveguiding layers and GaN cladding layers. At a lasing wavelength of 452 nm, the peak two-facet CW output power from an LD with uncoated facets was 1.71 W at a current of 3 A, corresponding to an optical power density of 32.04 MW/cm2 on each facet. The dependence of output power on current did not change with repeated CW measurements, indicating that the polished facets did not degrade under high-power CW operation. These results show that polished facets are a viable alternative to cleaved or etched facets for high-power CW semi-polar LDs.

CW operation of high-power blue laser diodes with polished facets on semi-polar ( 20 2 ¯ 1 ¯ ) GaN substrates

KAUST Repository

Pourhashemi, A.; Farrell, R.M.; Cohen, D.A.; Becerra, D.L.; DenBaars, S.P.; Nakamura, S.

2016-01-01

Continuous wave (CW) operation of high-power blue laser diodes (LDs) with polished facets on semi-polar (202̅1̅) gallium nitride (GaN) substrates is demonstrated. Ridge waveguide LDs were fabricated using indium GaN waveguiding layers and GaN cladding layers. At a lasing wavelength of 452 nm, the peak two-facet CW output power from an LD with uncoated facets was 1.71 W at a current of 3 A, corresponding to an optical power density of 32.04 MW/cm2 on each facet. The dependence of output power on current did not change with repeated CW measurements, indicating that the polished facets did not degrade under high-power CW operation. These results show that polished facets are a viable alternative to cleaved or etched facets for high-power CW semi-polar LDs.

The formation of pollen in male flowers and yearly atmospheric pollen counts of Cryptomeria japonica in the following year

Directory of Open Access Journals (Sweden)

Hideaki Taira

1998-01-01

Full Text Available Prediction of yearly atmospheric pollen counts is a very important component in the prevention of allergenic symptoms. We investigated the relationship between atomspheric pollen counts and the formation of male flowers of Cryptomeriajaponica D. Don (C. japonica. An atmospheric pollen survey of C. japonica was conducted from 1983 to 1996 using a Durham’s sampler. A regression analysis was performed between the total pollen count and July temperature in previous years. The atmospheric pollen counts of C. japonica had a high positive correlation with the mean temperature in July of the previous year. However, the predicted using average mean July temperature records of the previous year were insufficient, especially in years following high pollen count. In experimental conditions, using 60 C. japonica trees in pots, the formation of male flowers was shown to increase with a rise in incubation temperature. In a forest of C. japonica, our results showed that the length and weight of new needle growth from old needles, which produced many flowers in the previous year, were shorter and lighter, respectively. These aerobiological and plant physiological studies provide evidence that a smaller number of pollen counts are a common result in a year following one in which many male flowers are produced, even if the mean July temperature of that year was high.

Fruit and seed characteristics of diploid seedless watermelon (citrullus lanatas) cultivars produced by soft-X-irradiated pollen

Energy Technology Data Exchange (ETDEWEB)

Sugiyama, Keita; Morishita, Masami [National Research Insti. of Vegetables, Ornamental Plants and Tea, Fukuoka (Japan). Kurume Branch

2000-11-01

We compared the differences in number of seeds, size of normal and empty seeds, and fruit quality of seedless fruit induced by soft- X- irradiated pollen to determine which cultivars are best suited for breeding and producing high quality seedless watermelon. Two wild types, eleven Japanese, one Chinese, and three American watermelon cultivars were studied. We also observed the effect of soft- X- rays on pollen germination and elongation of the pollen tube. The germination rates of pollen treated with 1000 to 2000 Gy of soft-X-ray were almost the same as those of the control, whereas the rate was significantly reduced at 3000 Gy. Soft-X- irradiated pollen germinated on a stigma, and the pollen tube elongated in the embryo sac. Watermelon fruit pollinated with pollen irradiated with 800 Gy of soft-X-ray had no normal seeds but only empty ones. To delineate the varietal differences by the number of empty seeds and seed size in seedless fruit, wild types, Japanese, Chinese, and American watermelon cultivars were investigated. The number and size of empty seeds varied among cultivars. A low correlation (r=0.272) existed between the total number of seeds in the control fruit and the number of empty seeds in the seedless fruit. Whereas, a high correlation (seed length: r=0.943, P<0.001, seed width: r=0.883, P < 0.001) was found between the size of normal seeds in control fruit and empty seeds in seedless fruit. Diploid seedless fruit was similar to control fruit in size, shape, color, rind thickness, sugar content, and days from pollination to maturity. (author)

Fruit and seed characteristics of diploid seedless watermelon (citrullus lanatas) cultivars produced by soft-X-irradiated pollen

International Nuclear Information System (INIS)

Sugiyama, Keita; Morishita, Masami

2000-01-01

We compared the differences in number of seeds, size of normal and empty seeds, and fruit quality of seedless fruit induced by soft- X- irradiated pollen to determine which cultivars are best suited for breeding and producing high quality seedless watermelon. Two wild types, eleven Japanese, one Chinese, and three American watermelon cultivars were studied. We also observed the effect of soft- X- rays on pollen germination and elongation of the pollen tube. The germination rates of pollen treated with 1000 to 2000 Gy of soft-X-ray were almost the same as those of the control, whereas the rate was significantly reduced at 3000 Gy. Soft-X- irradiated pollen germinated on a stigma, and the pollen tube elongated in the embryo sac. Watermelon fruit pollinated with pollen irradiated with 800 Gy of soft-X-ray had no normal seeds but only empty ones. To delineate the varietal differences by the number of empty seeds and seed size in seedless fruit, wild types, Japanese, Chinese, and American watermelon cultivars were investigated. The number and size of empty seeds varied among cultivars. A low correlation (r=0.272) existed between the total number of seeds in the control fruit and the number of empty seeds in the seedless fruit. Whereas, a high correlation (seed length: r=0.943, P<0.001, seed width: r=0.883, P < 0.001) was found between the size of normal seeds in control fruit and empty seeds in seedless fruit. Diploid seedless fruit was similar to control fruit in size, shape, color, rind thickness, sugar content, and days from pollination to maturity. (author)

Overview of TANGENT (Tandem Aerosol Nucleation and Growth ENvironment Tube) 2017 IOP Study

Science.gov (United States)

Tiszenkel, L.

2017-12-01

New particle formation consists of two steps: nucleation and growth of nucleated particles. However, most laboratory studies have been conducted under conditions where these two processes are convoluted together, thereby hampering the detailed understanding of the effect of chemical species and atmospheric conditions on two processes. The objective of the Tandem Aerosol Nucleation and Growth ENvironment Tube (TANGENT) laboratory study is to investigate aerosol nucleation and growth properties independently by separating these two processes in two different flow tubes. This research is a collaboration between the University of Alabama in Huntsville and the University of Delaware. In this poster we will present the experimental setup of TANGENT and summarize the key results from the first IOP (intense observation period) experiments undertaken during Summer 2017. Nucleation takes place in a temperature- and RH-controlled fast flow reactor (FT-1) where sulfuric acid forms from OH radicals and sulfur dioxide. Sulfuric acid and impurity base compounds are detected with chemical ionization mass spectrometers (CIMS). Particle sizes and number concentrations of newly nucleated particles are measured with a scanning mobility particle sizer (SMPS) and particle size magnifier (PSM), providing concentrations of particles between 1-100 nm. The nucleation particles are transferred directly to the growth tube (FT-2) where oxidants and biogenic organic precursors are added to grow nucleated nanoparticles. Sizes of particles after growth are analyzed with an additional SMPS and elemental chemical composition of 50 nm and above particles detected with a nano-aerosol mass spectrometer (NAMS). TANGENT provides the unique ability to conduct experiments that can monitor and control reactant concentrations, aerosol size and aerosol chemical composition during nucleation and growth. Experiments during this first IOP study have elucidated the effects of sulfur dioxide, particle size

The cysteine protease CEP1, a key executor involved in tapetal programmed cell death, regulates pollen development in Arabidopsis.

Science.gov (United States)

Zhang, Dandan; Liu, Di; Lv, Xiaomeng; Wang, Ying; Xun, Zhili; Liu, Zhixiong; Li, Fenglan; Lu, Hai

2014-07-01

Tapetal programmed cell death (PCD) is a prerequisite for pollen grain development in angiosperms, and cysteine proteases are the most ubiquitous hydrolases involved in plant PCD. We identified a papain-like cysteine protease, CEP1, which is involved in tapetal PCD and pollen development in Arabidopsis thaliana. CEP1 is expressed specifically in the tapetum from stages 5 to 11 of anther development. The CEP1 protein first appears as a proenzyme in precursor protease vesicles and is then transported to the vacuole and transformed into the mature enzyme before rupture of the vacuole. cep1 mutants exhibited aborted tapetal PCD and decreased pollen fertility with abnormal pollen exine. A transcriptomic analysis revealed that 872 genes showed significantly altered expression in the cep1 mutants, and most of them are important for tapetal cell wall organization, tapetal secretory structure formation, and pollen development. CEP1 overexpression caused premature tapetal PCD and pollen infertility. ELISA and quantitative RT-PCR analyses confirmed that the CEP1 expression level showed a strong relationship to the degree of tapetal PCD and pollen fertility. Our results reveal that CEP1 is a crucial executor during tapetal PCD and that proper CEP1 expression is necessary for timely degeneration of tapetal cells and functional pollen formation. © 2014 American Society of Plant Biologists. All rights reserved.

Bandwidth broadening effect in a traveling-wave-tube amplifier by using impulse electron beam

International Nuclear Information System (INIS)

Jung, Sang Wook; Choi, Jin Joo; Kim, Seon Joo

2012-01-01

This paper reports on a wideband amplification mechanism involving an impulse electron beam. To prove broadband amplification with the impulse beam, we perform 3-dimensional particle-in-cell (3D PIC) code simulation. An impulse electron beam with a pulse width of 1 ns with electric potential 17.2 kV is injected into an interaction circuit of a coupled-cavity traveling-wave-tube (CCTWT) driven by a continuous-wave (CW) signal of 29.1 GHz. The resulting output bandwidth was 2.96%, and the peak output power of 713 W was the same as that obtained with CW operation at a single frequency. The simulation yielded very similar results with ultra short impulse signal from the simulation.

Application of M-type cathodes to high-power cw klystrons

Science.gov (United States)

Isagawa, S.; Higuchi, T.; Kobayashi, K.; Miyake, S.; Ohya, K.; Yoshida, M.

1999-05-01

Two types of high-power cw klystrons have been widely used at KEK in both TRISTAN and KEKB e +e - collider projects: one is a 0.8 MW/1.0 MW tube, called YK1302/YK1303 (Philips); the other is a 1.2 MW tube, called E3786/E3732 (Toshiba). Normally, the dispenser cathodes of the `B-type' and the `S-type' have been used, respectively, but for improved versions they have been replaced by low-temperature cathodes, called the `M-type'. An Os/Ru coating was applied to the former, whereas an Ir one was applied to the latter. Until now, all upgraded tubes installing M-type cathodes, 9 and 8 in number, respectively, have worked successfully without any dropout. A positive experience concerning the lifetime under real operation conditions has been obtained. M-type cathodes are, however, more easily poisoned. One tube installing an Os/Ru-coated cathode showed a gradual, and then sudden decrease in emission during an underheating test, although the emission could fortunately be recovered by aging at the KEK test field. Once sufficiently aged, the emission of an Ir-coated cathode proved to be very high and stable, and its lifetime is expected to be very long. One disadvantage of this cathode is, however, susceptibility to gas poisoning and the necessity of long-term initial aging. New techniques, like ion milling and fine-grained tungsten top layers, were not as successful as expected from their smaller scale applications to shorten the initial aging period. A burn-in process at higher cathode loading was efficient to make the poisoned cathode active and to decrease unwanted Wehnelt emission. On top of that, the emission cooling, and thus thermal conductivity near the emitting layer could play an important role in such large-current cathodes as ours.

Evaluation of the Nutritional and Storage Quality of Meatballs Formulated with Bee Pollen.

Science.gov (United States)

Turhan, Sadettin; Yazici, Fehmi; Saricaoglu, Furkan Turker; Mortas, Mustafa; Genccelep, Huseyin

2014-01-01

In this study, the nutritional and storage quality of meatballs formulated with different levels (0, 1.5, 3.0, 4.5 and 6.0%) of bee pollen were investigated during storage at 41℃ for 9 d. Protein content of meatballs increased, while moisture content decreased with increased pollen. The addition of pollen improved cooking loss but decreased the redness (Hunter a value) and sensory scores. Textural parameters (hardness, springsness, gumminess, and chewiness) were affected by pollen addition and the hardness and gumminess values of meatballs decreased as the pollen content increased. While C18:0 content of meatballs slightly decreased with pollen addition, C18:2n-6c, C18:3n-3, C20:5n-3, and PUFA contents increased. The PUFA/saturated fatty acids (P/S) ratio increased from 0.05 in the control to 0.09 in meatballs with 6.0% pollen. The n-6/n-3 ratio decreased from 11.84 in the control to 3.65 in the meatballs with 6.0% pollen. The addition of pollen retarded the lipid oxidation and inhibited the bacterial growth in meatballs. The pH, redness, TBA value and total aerobic mesophilic bacteria, coliform bacteria and S. aureus counts values changed significantly during storage. The results suggest that bee pollen could be added to enhance the nutritional and storage quality of meatballs with minimal changes in composition and/or sensory properties.

KIRA1 and ORESARA1 terminate flower receptivity by promoting cell death in the stigma of Arabidopsis.

Science.gov (United States)

Gao, Zhen; Daneva, Anna; Salanenka, Yuliya; Van Durme, Matthias; Huysmans, Marlies; Lin, Zongcheng; De Winter, Freya; Vanneste, Steffen; Karimi, Mansour; Van de Velde, Jan; Vandepoele, Klaas; Van de Walle, Davy; Dewettinck, Koen; Lambrecht, Bart N; Nowack, Moritz K

2018-05-28

Flowers have a species-specific functional life span that determines the time window in which pollination, fertilization and seed set can occur. The stigma tissue plays a key role in flower receptivity by intercepting pollen and initiating pollen tube growth toward the ovary. In this article, we show that a developmentally controlled cell death programme terminates the functional life span of stigma cells in Arabidopsis. We identified the leaf senescence regulator ORESARA1 (also known as ANAC092) and the previously uncharacterized KIRA1 (also known as ANAC074) as partially redundant transcription factors that modulate stigma longevity by controlling the expression of programmed cell death-associated genes. KIRA1 expression is sufficient to induce cell death and terminate floral receptivity, whereas lack of both KIRA1 and ORESARA1 substantially increases stigma life span. Surprisingly, the extension of stigma longevity is accompanied by only a moderate extension of flower receptivity, suggesting that additional processes participate in the control of the flower's receptive life span.

Substrate engineering for Ni-assisted growth of carbon nano-tubes

Energy Technology Data Exchange (ETDEWEB)

Kolahdouz, Z.; Kolahdouz, M. [Department of Electrical and Computer Engineering, Nano-electronic Laboratory, University of Tehran, Tehran (Iran, Islamic Republic of); Ghanbari, H. [Tarbiat Modarres University, Tehran (Iran, Islamic Republic of); Mohajerzadeh, S. [Department of Electrical and Computer Engineering, Nano-electronic Laboratory, University of Tehran, Tehran (Iran, Islamic Republic of); Naureen, S. [School of Information and Communication Technology, KTH (Royal Institute of Technology) Kista (Sweden); Radamson, H.H., E-mail: rad@kth.se [School of Information and Communication Technology, KTH (Royal Institute of Technology) Kista (Sweden)

2012-10-01

The growth of carbon multi-walled nano-tubes (MWCNTs) using metal catalyst (e.g. Ni, Co, and Fe) has been extensively investigated during the last decade. In general, the physical properties of CNTs depend on the type, quality and diameter of the tubes. One of the parameters which affects the diameter of a MWCNT is the size of the catalyst metal islands. Considering Ni as the metal catalyst, the formed silicide layer agglomerates (island formation) after a thermal treatment. One way to decrease the size of Ni islands is to apply SiGe as the base for the growth. In this study, different methods based on substrate engineering are proposed to change/control the MWCNT diameters. These include (i) well-controlled oxide openings containing Ni to miniaturize the metal island size, and (ii) growth on strained or partially relaxed SiGe layers for smaller Ni silicide islands.

Sequence Control System of 1-MW CW Klystron for the PEFP

CERN Document Server

Park, Byoung R; Chun Myung Hwan; Han Yeung Jin; Hyo Jeong Maeng; Kim Sung Chul; Yang Jae Seok; Yu In Ha

2005-01-01

Sequence control system of 1-MW CW klystron for the PEFP (Proton Engineering Frontier Project) has been developed in order to drive the 1-MW klystron amplifier. The system is able to control several power supplies and many environment conditions. The hardware of sequence control and the interlock system are based on the Allen-Bradley's SLC500 Program Logic Controller (PLC). Also the system can be controlled by a touch screen at local mode or Ethernet network with high level HMI at remote mode.

Colonoscopic allergen provocation test with rBet v 1 in patients with pollen-associated food allergy.

Science.gov (United States)

Pickert, C N; Lorentz, A; Manns, M P; Bischoff, S C

2012-10-01

After consumption of fruits, nuts, and vegetables, several patients with pollen allergy experience gastrointestinal (GI) tract symptoms that are possibly caused by pollen-associated food allergy. The aim of this study was to evaluate the colonoscopic allergen provocation (COLAP) test using the recombinant birch pollen allergen Bet v 1 (rBet v 1) for in vivo diagnosis of pollen-associated food allergy manifesting in the GI tract. Thirty-four patients with a history of adverse reactions to food, GI tract symptoms, and birch pollen pollinosis and five healthy controls underwent COLAP test. Twenty minutes after endoscopic challenge of the cecal mucosa with rBet v 1, the mucosal wheal and flare reaction was registered semiquantitatively, and tissue biopsy specimens were examined for eosinophil mucosal activation. The mucosal reaction to rBet v 1 was correlated with the presence of pollinosis (P = 0.004), history of adverse reaction to Bet v 1-associated food allergens (P = 0.001), and tissue eosinophils' activation (P foods and in four of 18 (22%) patients with a negative history (P food allergy manifesting in the GI tract. © 2012 John Wiley & Sons A/S.

Honey bee (Apis mellifera) nurses do not consume pollens based on their nutritional quality.

Science.gov (United States)

Corby-Harris, Vanessa; Snyder, Lucy; Meador, Charlotte; Ayotte, Trace

2018-01-01

Honey bee workers (Apis mellifera) consume a variety of pollens to meet the majority of their requirements for protein and lipids. Recent work indicates that honey bees prefer diets that reflect the proper ratio of nutrients necessary for optimal survival and homeostasis. This idea relies on the precept that honey bees evaluate the nutritional composition of the foods provided to them. While this has been shown in bumble bees, the data for honey bees are mixed. Further, there is controversy as to whether foragers can evaluate the nutritional value of pollens, especially if they do not consume it. Here, we focused on nurse workers, who eat most of the pollen coming into the hive. We tested the hypothesis that nurses prefer diets with higher nutritional value. We first determined the nutritional profile, number of plant taxa (richness), and degree of hypopharyngeal gland (HG) growth conferred by three honey bee collected pollens. We then presented nurses with these same three pollens in paired choice assays and measured consumption. To further test whether nutrition influenced preference, we also presented bees with natural pollens supplemented with protein or lipids and liquid diets with protein and lipid ratios equal to the natural pollens. Different pollens conferred different degrees of HG growth, but despite these differences, nurse bees did not always prefer the most nutritious pollens. Adding protein and/or lipids to less desirable pollens minimally increased pollen attractiveness, and nurses did not exhibit a strong preference for any of the three liquid diets. We conclude that different pollens provide different nutritional benefits, but that nurses either cannot or do not assess pollen nutritional value. This implies that the nurses may not be able to communicate information about pollen quality to the foragers, who regulate the pollens coming into the hive.

Honey bee (Apis mellifera nurses do not consume pollens based on their nutritional quality.

Directory of Open Access Journals (Sweden)

Vanessa Corby-Harris

Full Text Available Honey bee workers (Apis mellifera consume a variety of pollens to meet the majority of their requirements for protein and lipids. Recent work indicates that honey bees prefer diets that reflect the proper ratio of nutrients necessary for optimal survival and homeostasis. This idea relies on the precept that honey bees evaluate the nutritional composition of the foods provided to them. While this has been shown in bumble bees, the data for honey bees are mixed. Further, there is controversy as to whether foragers can evaluate the nutritional value of pollens, especially if they do not consume it. Here, we focused on nurse workers, who eat most of the pollen coming into the hive. We tested the hypothesis that nurses prefer diets with higher nutritional value. We first determined the nutritional profile, number of plant taxa (richness, and degree of hypopharyngeal gland (HG growth conferred by three honey bee collected pollens. We then presented nurses with these same three pollens in paired choice assays and measured consumption. To further test whether nutrition influenced preference, we also presented bees with natural pollens supplemented with protein or lipids and liquid diets with protein and lipid ratios equal to the natural pollens. Different pollens conferred different degrees of HG growth, but despite these differences, nurse bees did not always prefer the most nutritious pollens. Adding protein and/or lipids to less desirable pollens minimally increased pollen attractiveness, and nurses did not exhibit a strong preference for any of the three liquid diets. We conclude that different pollens provide different nutritional benefits, but that nurses either cannot or do not assess pollen nutritional value. This implies that the nurses may not be able to communicate information about pollen quality to the foragers, who regulate the pollens coming into the hive.

Honey bee (Apis mellifera) nurses do not consume pollens based on their nutritional quality

Science.gov (United States)

Snyder, Lucy; Meador, Charlotte; Ayotte, Trace

2018-01-01

Honey bee workers (Apis mellifera) consume a variety of pollens to meet the majority of their requirements for protein and lipids. Recent work indicates that honey bees prefer diets that reflect the proper ratio of nutrients necessary for optimal survival and homeostasis. This idea relies on the precept that honey bees evaluate the nutritional composition of the foods provided to them. While this has been shown in bumble bees, the data for honey bees are mixed. Further, there is controversy as to whether foragers can evaluate the nutritional value of pollens, especially if they do not consume it. Here, we focused on nurse workers, who eat most of the pollen coming into the hive. We tested the hypothesis that nurses prefer diets with higher nutritional value. We first determined the nutritional profile, number of plant taxa (richness), and degree of hypopharyngeal gland (HG) growth conferred by three honey bee collected pollens. We then presented nurses with these same three pollens in paired choice assays and measured consumption. To further test whether nutrition influenced preference, we also presented bees with natural pollens supplemented with protein or lipids and liquid diets with protein and lipid ratios equal to the natural pollens. Different pollens conferred different degrees of HG growth, but despite these differences, nurse bees did not always prefer the most nutritious pollens. Adding protein and/or lipids to less desirable pollens minimally increased pollen attractiveness, and nurses did not exhibit a strong preference for any of the three liquid diets. We conclude that different pollens provide different nutritional benefits, but that nurses either cannot or do not assess pollen nutritional value. This implies that the nurses may not be able to communicate information about pollen quality to the foragers, who regulate the pollens coming into the hive. PMID:29324841

Ozone affects pollen viability and NAD(P)H oxidase release from Ambrosia artemisiifolia pollen

International Nuclear Information System (INIS)

Pasqualini, Stefania; Tedeschini, Emma; Frenguelli, Giuseppe; Wopfner, Nicole; Ferreira, Fatima; D'Amato, Gennaro; Ederli, Luisa

2011-01-01

Air pollution is frequently proposed as a cause of the increased incidence of allergy in industrialised countries. We investigated the impact of ozone (O 3 ) on reactive oxygen species (ROS) and allergen content of ragweed pollen (Ambrosia artemisiifolia). Pollen was exposed to acute O 3 fumigation, with analysis of pollen viability, ROS and nitric oxide (NO) content, activity of nicotinamide adenine dinucleotide phosphate (NAD[P]H) oxidase, and expression of major allergens. There was decreased pollen viability after O 3 fumigation, which indicates damage to the pollen membrane system, although the ROS and NO contents were not changed or were only slightly induced, respectively. Ozone exposure induced a significant enhancement of the ROS-generating enzyme NAD(P)H oxidase. The expression of the allergen Amb a 1 was not affected by O 3 , determined from the mRNA levels of the major allergens. We conclude that O 3 can increase ragweed pollen allergenicity through stimulation of ROS-generating NAD(P)H oxidase. - Highlights: → O 3 reduces the viability of ragweed pollen. → ROS and allergens of ragweed pollen were not affected by O 3 exposure. → O 3 enhances the activity of the ROS-generating enzyme NAD(P)H oxidase. → O 3 increases ragweed pollen allergenicity through NAD(P)H-oxidase stimulation. - This study focuses on the effects of the atmospheric pollutant ozone on ROS content and NAD(P)H oxidase activity of ragweed pollen grains.

Ozone affects pollen viability and NAD(P)H oxidase release from Ambrosia artemisiifolia pollen

Energy Technology Data Exchange (ETDEWEB)

Pasqualini, Stefania, E-mail: spas@unipg.it [Department of Applied Biology, University of Perugia, Perugia (Italy); Tedeschini, Emma; Frenguelli, Giuseppe [Department of Applied Biology, University of Perugia, Perugia (Italy); Wopfner, Nicole; Ferreira, Fatima [Department of Molecular Biology, CD Laboratory for Allergy Diagnosis and Therapy, University of Salzburg, Salzburg (Austria); D' Amato, Gennaro [Division of Respiratory and Allergic Diseases, ' A. Cardarelli' High Speciality Hospital, Naples (Italy); Ederli, Luisa [Department of Applied Biology, University of Perugia, Perugia (Italy)

2011-10-15

Air pollution is frequently proposed as a cause of the increased incidence of allergy in industrialised countries. We investigated the impact of ozone (O{sub 3}) on reactive oxygen species (ROS) and allergen content of ragweed pollen (Ambrosia artemisiifolia). Pollen was exposed to acute O{sub 3} fumigation, with analysis of pollen viability, ROS and nitric oxide (NO) content, activity of nicotinamide adenine dinucleotide phosphate (NAD[P]H) oxidase, and expression of major allergens. There was decreased pollen viability after O{sub 3} fumigation, which indicates damage to the pollen membrane system, although the ROS and NO contents were not changed or were only slightly induced, respectively. Ozone exposure induced a significant enhancement of the ROS-generating enzyme NAD(P)H oxidase. The expression of the allergen Amb a 1 was not affected by O{sub 3}, determined from the mRNA levels of the major allergens. We conclude that O{sub 3} can increase ragweed pollen allergenicity through stimulation of ROS-generating NAD(P)H oxidase. - Highlights: > O{sub 3} reduces the viability of ragweed pollen. > ROS and allergens of ragweed pollen were not affected by O{sub 3} exposure. > O{sub 3} enhances the activity of the ROS-generating enzyme NAD(P)H oxidase. > O{sub 3} increases ragweed pollen allergenicity through NAD(P)H-oxidase stimulation. - This study focuses on the effects of the atmospheric pollutant ozone on ROS content and NAD(P)H oxidase activity of ragweed pollen grains.

Effect of gamma-radiation on grapevine pollen

International Nuclear Information System (INIS)

Bozhinova-Boneva, I.

1974-01-01

A test was performed in 1968-1971. Pollen of the Bolgar and Muscat of Hamburg varieties was irradiated with doses of 0.5, 1.0, 1.5, 10, 20, 30, 40 and 60 kR. Variously treated pollen was used for pollinating 10-20 catkins of Chaoush variety. The viability of treated pollen was checked on 1% agarmedium at 25 0 C. Low doses of 0.5 and 1.0 kR have exerted a stimulant effect on the pollen sprouting. A dose of 60 kR did not bring about full loss of pollen viability. As the dose increased the number of hybrid seeds produced declined. The Chaoush x Bolgar cross as a control yielded 459 seeds; 580 from 0.5 kR-treated pollen; 530 from 1.0 kR-treated pollen; 324 from 1.5 kR-; 287 from 7 kR-; 202 from 10 kR-; 96 from 20 kR-; 46 from 30 kR-; 19 from 40 kR- and no seeds from 60 kR-treated pollen were obtained. A similar picture was obtained for the other cross. The Chaoush x Bolgar cross produced the following number of hybrid seeds: control - 13; 0.5 kR - 16; 1.0kR - 14; 5 kR - 14; 7 kR - 10; 10 kR - 6 seeds and from over 20 kR - nil

Flower associations and nesting of the pollen wasp Quartinia major Kohl, 1898 (Hymenoptera, Vespidae, Masarinae in Morocco

Directory of Open Access Journals (Sweden)

Volker Mauss

2018-02-01

Full Text Available Females of Quartinia major Kohl were observed to visit flowers of Pulicaria mauritanica Batt., Cladanthus arabicus (L. Cass. and Asteriscus graveolens (Forssk. Less., (all Asteroideae Asteraceae at two localities in southern Morocco. Pollen in the provisions of two brood cells was more than 99% Aster-type (Asteroideae, indicating broad oligolecty. During pollen uptake from P. mauritanica, the females of Q. major employed a hitherto undescribed harvesting technique: They used their mouthparts to squeeze pollen from the corolla tubes of early male phase disc florets. Pollen was ingested immediately after it had been extracted. The nest was a multicellular subterranean burrow excavated in friable soil and surmounted by a turret. The nest walls were stabilized with self-generated silk.

GDP-D-mannose epimerase regulates male gametophyte development, plant growth and leaf senescence in Arabidopsis.

Science.gov (United States)

Qi, Tiancong; Liu, Zhipeng; Fan, Meng; Chen, Yan; Tian, Haixia; Wu, Dewei; Gao, Hua; Ren, Chunmei; Song, Susheng; Xie, Daoxin

2017-09-04

Plant GDP-D-mannose epimerase (GME) converts GDP-D-mannose to GDP-L-galactose, a precursor of both L-ascorbate (vitamin C) and cell wall polysaccharides. However, the genetic functions of GME in Arabidopsis are unclear. In this study, we found that mutations in Arabidopsis GME affect pollen germination, pollen tube elongation, and transmission and development of the male gametophyte through analysis of the heterozygous GME/gme plants and the homozygous gme plants. Arabidopsis gme mutants also exhibit severe growth defects and early leaf senescence. Surprisingly, the defects in male gametophyte in the gme plants are not restored by L-ascorbate, boric acid or GDP-L-galactose, though boric acid rescues the growth defects of the mutants, indicating that GME may regulate male gametophyte development independent of L-ascorbate and GDP-L-galactose. These results reveal key roles for Arabidopsis GME in reproductive development, vegetative growth and leaf senescence, and suggest that GME regulates plant growth and controls male gametophyte development in different manners.

[Pollen quality of Pinus pithyusa Stev. in natural stands of the South Crimea].

Science.gov (United States)

Koba, V P

2005-01-01

Results of long-term research of germination rate, vitality and dynamics of in vitro growth of P. pithyusa pollen are shown. Dynamics of pollen quality under the action of external factors has been defined.

Honey bee foraging ecology: Season but not landscape diversity shapes the amount and diversity of collected pollen.

Directory of Open Access Journals (Sweden)

Nadja Danner

Full Text Available The availability of pollen in agricultural landscapes is essential for the successful growth and reproduction of honey bee colonies (Apis mellifera L.. The quantity and diversity of collected pollen can influence the growth and health of honey bee colonies, but little is known about the influence of landscape structure on pollen diet. In a field experiment, we rotated 16 honey bee colonies across 16 agricultural landscapes, used traps to collect samples of collected pollen and observed intra-colonial dance communication to gain information about foraging distances. DNA metabarcoding was applied to analyze mixed pollen samples. Neither the amount of collected pollen nor pollen diversity was related to landscape diversity. However, we found a strong seasonal variation in the amount and diversity of collected pollen in all sites independent of landscape diversity. The observed increase in foraging distances with decreasing landscape diversity suggests that honey bees compensated for lower landscape diversity by increasing their pollen foraging range in order to maintain pollen amount and diversity. Our results underscore the importance of a diverse pollen diet for honey bee colonies. Agri-environmental schemes aiming to support pollinators should focus on possible spatial and temporal gaps in pollen availability and diversity in agricultural landscapes.

The effects of pesticides on morphology, viability, and germination of Blackberry (Rubus glaucus Benth.) and Tree tomato (Solanum betaceum Cav.) pollen grains.

Science.gov (United States)

Padilla, Flavio; Soria, Norman; Oleas, Abrahan; Rueda, Darwin; Manjunatha, Bangeppagari; Kundapur, Rajesh R; Maddela, Naga Raju; Rajeswari, Bugude

2017-07-01

The objective of this study was to determine the effect of application of pesticides on morphology, viability, and germination of pollen grains of Blackberry (Rubus glaucus Benth.) and Tree tomato (Solanum betaceum Cav.). The study was performed at Patate, Tungurahua province, Ecuador and was divided into two phases. Phase one dedicated to the study of morphology, viability, and identification of nutrient solution for better germination of pollen grains and phase two for the analysis of the effect of conventional, organic, and biological pesticides on pollen grain germination and pollen tube length. To study pollen morphology, pollens were extracted by hand pressure and was analyzed by optical and electron microscopy. The viable pollen grains were identified by staining with 1% acetocarmine. Even though Tree tomato and Blackberry pollen grains are morphologically similar, their exine shapes differ. We observed four times increase in pollen germination rate when suspended in nutrient solution (Sucrose with Boric acid) than control (water). Pollen grains under nutrient solution were subjected to different groups of pesticides for the period of 2, 4, and 6 h. With respect to pesticide affect, the Blackberry pollen grain germination followed the following order: Lecaniceb > Beauveb > Metazeb => Myceb > Control. However, the effect on Tree tomato pollen grains was as follows: Lecaniceb > Myceb > Cantus > Bacillus thuringiensis > Kripton > Control. As per as pollen grain germination is concerned, we observed that the chemical pesticides are more harmful than other pesticides. So, it is necessary to perform screening test for different pesticides and their effect on pollen grain germination before applying to the fields.

Development of High Power Vacuum Tubes for Accelerators and Plasma Heating

International Nuclear Information System (INIS)

Srivastava, Vishnu

2012-01-01

High pulsed power magnetrons and klystrons for medical and industrial accelerators, and high CW power klystrons and gyrotrons for plasma heating in tokamak, are being developed at CEERI. S-band 2.0MW pulsed tunable magnetrons of centre frequency 2856MHz and 2998 MHz were developed, and S-band 2.6MW pulsed tunable magnetron is being developed for medical LINAC, and 3MW pulsed tunable magnetron is being developed for industrial accelerator. S-band (2856MHz), 5MW pulsed klystron was developed for particle accelerator, and S-band 6MW pulsed klystron is under development for 10MeV industrial accelerator. 350MHz, 100kW (CW) klystron is being developed for proton accelerator, and C-band 250kW (CW) klystron is being developed for plasma heating. 42GHz, 200kW (CW/Long pulse) gyrotron is under development for plasma heating. Plasma filled tubes are also being developed for switching. 25kV/1kA and 40kV/3kA thyratrons were developed for high voltage high current switching in pulse modulators for magnetrons and klystrons. 25kV/3kA Pseudospark switch of current rise time of 1kA/|a-sec and pulse repetition rate of 500Hz is being developed. Plasma assisted high power microwave device is also being investigated.

Development of High Power Vacuum Tubes for Accelerators and Plasma Heating

Science.gov (United States)

Srivastava, Vishnu

2012-11-01

High pulsed power magnetrons and klystrons for medical and industrial accelerators, and high CW power klystrons and gyrotrons for plasma heating in tokamak, are being developed at CEERI. S-band 2.0MW pulsed tunable magnetrons of centre frequency 2856MHz and 2998 MHz were developed, and S-band 2.6MW pulsed tunable magnetron is being developed for medical LINAC, and 3MW pulsed tunable magnetron is being developed for industrial accelerator. S-band (2856MHz), 5MW pulsed klystron was developed for particle accelerator, and S-band 6MW pulsed klystron is under development for 10MeV industrial accelerator. 350MHz, 100kW (CW) klystron is being developed for proton accelerator, and C-band 250kW (CW) klystron is being developed for plasma heating. 42GHz, 200kW (CW/Long pulse) gyrotron is under development for plasma heating. Plasma filled tubes are also being developed for switching. 25kV/1kA and 40kV/3kA thyratrons were developed for high voltage high current switching in pulse modulators for magnetrons and klystrons. 25kV/3kA Pseudospark switch of current rise time of 1kA/|a-sec and pulse repetition rate of 500Hz is being developed. Plasma assisted high power microwave device is also being investigated.

IGSCC growth behaviors of Alloy 690 in hydrogenated high temperature water

Energy Technology Data Exchange (ETDEWEB)

Arioka, K.; Yamada, T.; Miyamoto, T.; Terachi, T. [INSS, (Japan)

2011-07-01

The rate of growth of stress corrosion cracking (SCC) was measured for cold worked and thermally treated and solution treated Alloy 690 (UNS N06690, CW TT690, CW ST690) in hydrogenated pressurized water reactor (PWR) primary water under static load condition. Three important patterns were observed: First, Intergranular stress corrosion cracking (IGSCC) was observed on both TT and ST690 even in static load condition if materials were heavily cold worked although the rate of SCC growth was much slower than that of CW mill annealed Alloy 600. Furthermore much rapid SCC growth was recognized in 20% CW TT690 than that of 20% CW ST690. This is quite different result in the literature in high temperature caustic solution. Second, in order to assess the role of creep, rates of creep crack growth were measured in air, argon, and hydrogen gas environments using 20% CW TT690, and 20% CW MA600 in the range of temperatures between 360 and 460 C; intergranular creep cracking (IG creep cracking) was observed on the test materials even in air. Similar slope of 1/T-type temperature dependencies on IGSCC and IG creep crack growth were observed on 20% CW TT690. Similar fracture morphologies and similar 1/T-type temperature dependencies suggest that creep is important in the growth of IGSCC of CW TT690 in high temperature water. Third, cavities and pores were observed at grain boundaries near tips of SCC and creep although the size of the cavities and pores of SCC were much smaller than that of creep cracks. Also the population and size of cavities seem to decrease with decreasing test temperature. These results suggest that the difference in the size and population of cavities might be related with the difference in crack growth rate. And the cavities seem to be formed result from collapse of vacancies at grain boundaries as the crack embryo. This result suggests that diffusion of condensation of vacancies in high stressed fields occurs in high temperature water and gas environments

Growth and Identification of Bacteria in N-Halamine Dental Unit Waterline Tubing Using an Ultrapure Water Source

Science.gov (United States)

Porteous, Nuala; Luo, Jie; Hererra, Monica; Schoolfield, John; Sun, Yuyu

2011-01-01

This study examined bacterial growth and type on biofilm-controlling dental unit waterline (DUWL) tubing (T) and control manufacturer's tubing (C) in a laboratory DUWL model using ultrapure source water that was cycled through the lines. Sections of tubing lines were detached and examined for biofilm growth using SEM imaging at six sampling periods. Bacteria from inside surfaces of T and C, source unit, and reservoir were cultured and enumerated. At six months, organisms were molecularly identified from the alignment matches obtained from the top three BLAST searches for the 16S region. There was a 1–3 log increase in organism growth in a clean, nonsterile reservoir within an hour. Biofilm was established on the inside surfaces of C within three weeks, but not on T. Proteobacteria, and Sphingomonas spp. were identified in the source reservoir and C line, and a variation of the genera was found in T line. PMID:22220171

The Cysteine Protease CEP1, a Key Executor Involved in Tapetal Programmed Cell Death, Regulates Pollen Development in Arabidopsis[W][OPEN

Science.gov (United States)

Zhang, Dandan; Liu, Di; Lv, Xiaomeng; Wang, Ying; Xun, Zhili; Liu, Zhixiong; Li, Fenglan; Lu, Hai

2014-01-01

Tapetal programmed cell death (PCD) is a prerequisite for pollen grain development in angiosperms, and cysteine proteases are the most ubiquitous hydrolases involved in plant PCD. We identified a papain-like cysteine protease, CEP1, which is involved in tapetal PCD and pollen development in Arabidopsis thaliana. CEP1 is expressed specifically in the tapetum from stages 5 to 11 of anther development. The CEP1 protein first appears as a proenzyme in precursor protease vesicles and is then transported to the vacuole and transformed into the mature enzyme before rupture of the vacuole. cep1 mutants exhibited aborted tapetal PCD and decreased pollen fertility with abnormal pollen exine. A transcriptomic analysis revealed that 872 genes showed significantly altered expression in the cep1 mutants, and most of them are important for tapetal cell wall organization, tapetal secretory structure formation, and pollen development. CEP1 overexpression caused premature tapetal PCD and pollen infertility. ELISA and quantitative RT-PCR analyses confirmed that the CEP1 expression level showed a strong relationship to the degree of tapetal PCD and pollen fertility. Our results reveal that CEP1 is a crucial executor during tapetal PCD and that proper CEP1 expression is necessary for timely degeneration of tapetal cells and functional pollen formation. PMID:25035401

Small size neutron tube UNG-1

International Nuclear Information System (INIS)

Bespalov, D.F.; Mints, A.Z.; Shkol'nikov, A.S.

A tube UNG-1 (universal neutron gas-filled) is designed for the use in the well neutron generators IGN-1 and IGN-1-M (a pulse neutron generator). Their serial production in the USSR has been started in 1963. At the same year, the serial production of the tubes UNG-1 has been started. Thus, this tube is the first serial logging accelerating tube in the USSR. A Penning source, equipped with a hot cathode, was selected as an ion source of the tube

Gamma Irradiation Effects on Oil Palm (Elaies Guineensis) Pollen Viability, Fruits and Bunch Formations

International Nuclear Information System (INIS)

Aida Nazlyn Nazari; Azhar Mohamad; Shuhaimi Shamsuddin

2014-01-01

Assessing performance and genetic diversity of the wild material of oil palm is important for understanding genetic structure of natural oil palm populations towards improvement of the crops. This information is important for oil palm breeding programs, and also for continued ex-situ conservation of the germplasm and breeding program in Malaysia. Mutation induction is one of the alternative ways in creating variants for selection in the breeding program. In this study, evaluation on the effect of irradiated pollen towards pollen viability, bunches formation and no. of parthenocarpic fruits were conducted. Series of acute gamma radiation at dose 0, 10, 20, 40, 50, 100, 200, 300, 500, 100 and 2000 Gy were exposed to Elaies guineensis pollen. Increasing level of irradiation higher than 200 Grays (Gy) affects pollen viability based on the 12 consecutive days observation evaluated in situ conditions. Besides, at this level of irradiation (> 200 Gy), the pollen tube formation were disrupted and subsequently unable the pollen to reach the ovule which cause the embryo to aborted and contributed to the formation of parthenocarpic fruits and rotten bunches. These observations suggested that at low levels of irradiation (< 200 Gy) may damage only part of the generative nucleus while maintaining its capacity to fertilise the egg cells and lead to hybridization. (author)

Ozone affects pollen viability and NAD(P)H oxidase release from Ambrosia artemisiifolia pollen.

Science.gov (United States)

Pasqualini, Stefania; Tedeschini, Emma; Frenguelli, Giuseppe; Wopfner, Nicole; Ferreira, Fatima; D'Amato, Gennaro; Ederli, Luisa

2011-10-01

Air pollution is frequently proposed as a cause of the increased incidence of allergy in industrialised countries. We investigated the impact of ozone (O(3)) on reactive oxygen species (ROS) and allergen content of ragweed pollen (Ambrosia artemisiifolia). Pollen was exposed to acute O(3) fumigation, with analysis of pollen viability, ROS and nitric oxide (NO) content, activity of nicotinamide adenine dinucleotide phosphate (NAD[P]H) oxidase, and expression of major allergens. There was decreased pollen viability after O(3) fumigation, which indicates damage to the pollen membrane system, although the ROS and NO contents were not changed or were only slightly induced, respectively. Ozone exposure induced a significant enhancement of the ROS-generating enzyme NAD(P)H oxidase. The expression of the allergen Amb a 1 was not affected by O(3), determined from the mRNA levels of the major allergens. We conclude that O(3) can increase ragweed pollen allergenicity through stimulation of ROS-generating NAD(P)H oxidase. Copyright © 2011 Elsevier Ltd. All rights reserved.

Pollen

Science.gov (United States)

... that pollen can also be transported indoors on people and pets. Dry your clothes in an automatic dryer rather ... that pollen can also be transported indoors on people and pets. Dry your clothes in an automatic dryer rather ...

A recombinant Sal k 1 isoform as an alternative to the polymorphic allergen from Salsola kali pollen for allergy diagnosis.

Science.gov (United States)

Mas, Salvador; Boissy, Patrice; Monsalve, Rafael I; Cuesta-Herranz, Javier; Díaz-Perales, Araceli; Fernández, Javier; Colás, Carlos; Rodríguez, Rosalía; Barderas, Rodrigo; Villalba, Mayte

2015-01-01

The incidence of Amaranthaceae pollen allergy has increased due to the desertification occurring in many countries. In some regions of Spain, Salsola kali is the main cause of pollinosis, at almost the same level as olive and grass pollen. Sal k 1 - the sensitization marker of S. kali pollinosis - is used in clinical diagnosis, but is purified at a low yield from pollen. We aimed to produce a recombinant (r)Sal k 1 able to span the structural and immunological properties of the natural isoforms from pollen, and validate its potential use for diagnosis. Specific cDNA was amplified by PCR, cloned into the pET41b vector and used to transform BL21 (DE3) Escherichia coli cells. Immunoblotting, ELISA, basophil activation and skin-prick tests were used to validate the recombinant protein against Sal k 1 isolated from pollen. Sera and blood cells from S. kali pollen-sensitized patients and specific monoclonal and polyclonal antisera were used. rSal k 1 was produced in bacteria with a yield of 7.5 mg/l of cell culture. The protein was purified to homogeneity and structural and immunologically validated against the natural form. rSal k 1 exhibited a higher IgE cross-reactivity with plant-derived food extracts such as peanut, almond or tomato than with pollen sources such as Platanus acerifolia and Oleaceae members. rSal k 1 expressed in bacteria retains intact structural and immunological properties in comparison to the pollen-derived allergen. It spans the immunological properties of most of the isoforms found in pollen, and it might substitute natural Sal k 1 in clinical diagnosis. © 2015 S. Karger AG, Basel.

Efficient third harmonic generation of a CW-fibered 1.5 µm laser diode

Science.gov (United States)

Philippe, Charles; Chea, Erick; Nishida, Yoshiki; du Burck, Frédéric; Acef, Ouali

2016-10-01

We report on frequency tripling of CW-Telecom laser diode using two cascaded PPLN ridge nonlinear crystals, both used in single-pass configuration. All optical components used for this development are fibered, leading to a very compact and easy to use optical setup. We have generated up to 290 mW optical power in the green range, from 800 mW only of infrared power around 1.54 µm. This result corresponds to an optical conversion efficiency P 3 ω / P ω > 36 %. To our knowledge, this is best value ever demonstrated up today for a CW-third harmonic generation in single-pass configuration. This frequency tripling experimental setup was tested over more than 2 years of continuous operation, without any interruption. The compactness and the reliability of our device make it very suitable as a transportable optical oscillator. In particular, it paves the way for embedded applications thanks to the high level of long-term stability of the optical alignments.

Over-expression of miR158 causes pollen abortion in Brassica campestris ssp. chinensis.

Science.gov (United States)

Ma, Zhiming; Jiang, Jianxia; Hu, Ziwei; Lyu, Tianqi; Yang, Yang; Jiang, Jingjing; Cao, Jiashu

2017-02-01

We identified and cloned the two precursors of miR158 and its target gene in Brassica campestris ssp. chinensis, which both had high relative expression in the inflorescences. Further study revealed that over-expression of miR158 caused reduced pollen varbility, which was caused by the degradation of pollen contents from the binucleate microspore stage. These results first suggest the role of miR158 in pollen development of Brassica campestris ssp. chinensis. MicroRNAs (miRNAs) play crucial roles in many important growth and development processes both in plants and animals by regulating the expression of their target genes via mRNA cleavage or translational repression. In this study, miR158, a Brassicaceae specific miRNA, was functionally characterized with regard to its role in pollen development of non-heading Chinese cabbage (Brassica campestris ssp. chinensis). Two family members of miR158 in B. campestris, namely bra-miR158a1 and bra-miR158a2, and their target gene bra027656, which encodes a pentatricopeptide repeat (PPR) containing protein, were identified. Then, qRT-PCR analysis and GUS-reporter system revealed that both bra-miR158 and its target gene had relatively high expression levels in the inflorescences. Further study revealed that over-expression of miR158 caused reduced pollen varbility and pollen germination ratio, and the degradation of pollen contents from the binucleate microspore stage was also found in those deformed pollen grains, which led to pollen shrinking and collapse in later pollen development stage. These results first shed light on the importance of miR158 in pollen development of Brassica campestris ssp. chinensis.

Photoluminescence study of ZnO structures grown by aqueous chemical growth

International Nuclear Information System (INIS)

Kenanakis, G.; Androulidaki, M.; Vernardou, D.; Katsarakis, N.; Koudoumas, E.

2011-01-01

ZnO micro-structures were deposited by aqueous chemical growth on Si (100) substrates, their morphology and size depending on the growth period. Characterization of the structures was performed using X-ray diffraction, scanning electron microscopy and Raman spectroscopy. Photoluminescence spectra recorded at 18 and 295 K for 325 nm CW excitation indicated that these are strongly affected by the morphology of the structures. Rods and tubes emit stronger UV radiation, in contrast to stronger yellow-green emission observed for flower-like structures. A red shift of the UV emission was found for increasing input power, while, thermal annealing of the samples induced stimulated emission for quite high excitation intensities.

Calcium in pollen-pistil interaction in 'Petunia hybrida Hor'. Pt. 1. Localization of Ca2+ ions in mature pollen grain using pyroantimonate and autoradiographic methods

International Nuclear Information System (INIS)

Bednarska, E.; Butowt, R.

1994-01-01

The localization of Ca 2+ in the mature pollen grain and the flow of these ions the somatic tissues of the anther to the pollen grains has been studied using pyroantimonate and autoradiographic methods. In the pollen grain, Ca 2+ ions have been localized in the sporoderm in the cytoplasmic vesicles of probably dictyosomal origin. Calcium ions were transported into the sporoderm together with the compounds of degenerating tapetum. The material of degenerating tapetum forms pollen coat surrounding the mature pollen grains. (author). 18 refs, 9 figs

Nitric Oxide Binds to and Modulates the Activity of a Pollen Specific Arabidopsis Diacylglycerol Kinase

KAUST Repository

Wong, Aloysius Tze

2014-01-01

Nitric oxide (NO) is an important signaling molecule in plants. In the pollen of Arabidopsis thaliana, NO causes re-orientation of the growing tube and this response is mediated by 3′,5′-cyclic guanosine monophosphate (cGMP). However, in plants, NO

Can we improve pollen season definitions by using the symptom load index in addition to pollen counts?

International Nuclear Information System (INIS)

Bastl, Katharina; Kmenta, Maximilian; Geller-Bernstein, Carmi; Berger, Uwe; Jäger, Siegfried

2015-01-01

Airborne pollen measurements are the foundation of aerobiological research and provide essential raw data for various disciplines. Pollen itself should be considered a relevant factor in air quality. Symptom data shed light on the relationship of pollen allergy and pollination. The aim of this study is to assess the spatial variation of local, regional and national symptom datasets. Ten pollen season definitions are used to calculate the symptom load index for the birch and grass pollen seasons (2013–2014) in Austria. (1) Local, (2) regional and (3) national symptom datasets are used to examine spatial variations and a consistent pattern was found. In conclusion, national datasets are suitable for first insights where no sufficient local or regional dataset is available and season definitions based on percentages provide a practical solution, as they can be applied in regions with different pollen loads and produce more constant results. - Highlights: • The definition of the pollen season has an impact on the calculated symptom load. • Pollen season definitions based on percentages of total pollen are a practical solution. • The symptom load index is a robust tool to assess the allergy burden in a population. • Local, regional and national burdens of pollen allergy sufferers are comparable. - The symptom load index is a robust tool to assess the allergy burden in a population. Local, regional and national burdens of pollen allergy sufferers are comparable

Consumption of Bt Maize Pollen Containing Cry1Ie Does Not Negatively Affect Propylea japonica (Thunberg (Coleoptera: Coccinellidae

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Yonghui Li

2017-03-01

Full Text Available Propylea japonica (Thunberg (Coleoptera: Coccinellidae are prevalent predators and pollen feeders in East Asian maize fields. They are therefore indirectly (via prey and directly (via pollen exposed to Cry proteins within Bt-transgenic maize fields. The effects of Cry1Ie-producing transgenic maize pollen on the fitness of P. japonica was assessed using two dietary-exposure experiments in the laboratory. In the first experiment, survival, larval developmental time, adult fresh weight, and fecundity did not differ between ladybirds consuming Bt or non-Bt maize pollen. In the second experiment, none of the tested lethal and sublethal parameters of P. japonica were negatively affected when fed a rapeseed pollen-based diet containing Cry1Ie protein at 200 μg/g dry weight of diet. In contrast, the larval developmental time, adult fresh weight, and fecundity of P. japonica were significantly adversely affected when fed diet containing the positive control compound E-64. In both experiments, the bioactivity of the Cry1Ie protein in the food sources was confirmed by bioassays with a Cry1Ie-sensitive lepidopteran species. These results indicated that P. japonica are not affected by the consumption of Cry1Ie-expressing maize pollen and are not sensitive to the Cry1Ie protein, suggesting that the growing of Bt maize expressing Cry1Ie protein will pose a negligible risk to P. japonica.

Long-term storage method for soft X-ray irradiated 'Hyuganatsu' pollen

International Nuclear Information System (INIS)

Yano, S.; Tanaka, M.; Ohara, N.

2008-01-01

The long-term storage conditions for 'Hyuganatsu ' pollen that had been irradiated with soft X-rays was examined. This study, was aimed at production of 'Tosa-buntan' without formation of nuclear fruit. 1. We evaluated the germination rate of pollen that had been irradiated with soft X-ray (500 or 1,000 Gy) and stored at 3 deg C, -20 deg C, and -40 deg C. The germination rate was the same as that of unirradiated pollen, even after storage for 1 year. Soft X-ray irradiation did not influence the storage attributes of pollen. 2. In unirradiated pollen and pollen that had been irradiated with soft X-ray (500 or 1,000 Gy), temperature conditions necessary for storing from 3 months to 1 year were -20 deg C or less, and pollen stored at -40 deg C had a higher germination rate after 1 year. 3. The germination rate was 1% or less in 4 months if silica gel was sealed into a gas barrier bag with 1,000 Gy-irradiated pollen at a rate of 10:1 (w/w). The ability to germinate was completely lost after 1 year in these conditions. 4. We evaluated the effect of sealing methods on 1,000 Gy-irradiated pollen stored at -20 deg C. There was no difference in germination rates among pollen stored in gas-barrier bags, vacuum-packaged pollen, and pollen stored with nitrogen in gas-barrier bags. Moreover, the germination rate of 750 Gy-irradiated pollen stored at -20 deg C decreased from 3 months onwards when pollen was stored with a free-oxygen absorber (Ageless ZP). 5. Pollen that was treated with acetone before or after soft X-ray irradiation (750 Gy) withstood long-term storage of 1 year. Long-term storage was possible if pollen was stored at -20 deg C, as is the case for rough pollen

YouTube as a source of patient information on gallstone disease.

Science.gov (United States)

Lee, Jun Suh; Seo, Ho Seok; Hong, Tae Ho

2014-04-14

To investigate the quality of YouTube videos on gallstone disease and to assess viewer response according to quality. A YouTube search was performed on September 18, 2013, using the keywords ''gallbladder disease'', ''gallstone disease'', and ''gallstone treatment''. Three researchers assessed the source, length, number of views, number of likes, and days since upload. The upload source was categorised as physician or hospital (PH), medical website or TV channel, commercial website (CW), or civilian. A usefulness score was devised to assess video quality and to categorise the videos into ''very useful'', ''useful'', ''slightly useful'', or ''not useful''. Videos with misleading content were categorised as ''misleading''. One hundred and thirty-one videos were analysed. Seventy-four videos (56.5%) were misleading, 36 (27.5%) were slightly useful, 15 (11.5%) were useful, three (2.3%) were very useful, and three (2.3%) were not useful. The number of mean likes (1.3 ± 1.5 vs 17.2 ± 38.0, P = 0.007) and number of views (756.3 ± 701.0 vs 8910.7 ± 17094.7, P = 0.001) were both significantly lower in the very useful group compared with the misleading group. All three very useful videos were PH videos. Among the 74 misleading videos, 64 (86.5%) were uploaded by a CW. There was no correlation between usefulness and the number of views, the number of likes, or the length. The "gallstone flush" was the method advocated most frequently by misleading videos (25.7%). More than half of the YouTube videos on gallstone disease are misleading. Credible videos uploaded by medical professionals and filtering by the staff of YouTube appear to be necessary.

Assessment of the Olea pollen and its major allergen Ole e 1 concentrations in the bioearosol of two biogeographical areas

Science.gov (United States)

Moreno-Grau, S.; Aira, M. J.; Elvira-Rendueles, B.; Fernández-González, M.; Fernández-González, D.; García-Sánchez, A.; Martínez-García, M. J.; Moreno, J. M.; Negral, L.; Vara, A.; Rodríguez-Rajo, F. J.

2016-11-01

The Olea pollen is currently an important allergy source. In some regions of Southern Spain, olive pollen is the main cause of allergic sensitization exceeding 40% of the sensitized individuals. Due to the scarce presence of olive trees in Northern Spain, limited to some cultivated fields in the South of the Galicia region where they also grow wild, only 8% of the sensitized individuals showed positive results for Olea pollen. The aim of the paper was to assess the behaviour pattern of the Olea pollen and its aeroallergens in the atmosphere, as this information could help us to improve the understanding and prevention of clinical symptoms. Airborne Olea pollen and Ole e 1 allergens were quantified in Cartagena (South-eastern Spain) and Ourense (North-western Spain). A volumetric pollen trap and a Burkard Cyclone sampler were used for pollen and allergen quantification. The Olea flowering took place in April or May in both biometeorological sampling areas. The higher concentrations were registered in the Southern area of Spain, for both pollen and Ole e 1, with values 8 times higher for pollen concentrations and 40 times higher for allergens. An alternate bearing pattern could be observed, characterized by years with high pollen values and low allergen concentrations and vice versa. Moreover, during some flowering seasons the allergen concentrations did not correspond to the atmospheric pollen values. Variations in weather conditions or Long Distance Transport (LDT) processes could explain the discordance. The back trajectory analysis shows that the most important contributions of pollen and allergens in the atmosphere are coincident with air masses passing through potential source areas. The exposure to olive pollen may not be synonym of antigen exposure.

A temporal dimension to the influence of pollen rewards on bee behaviour and fecundity in Aloe tenuior.

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Karl J Duffy

Full Text Available The net effect of pollen production on fecundity in plants can range from negative--when self-pollen interferes with fecundity due to incompatibility mechanisms, to positive--when pollen availability is associated with increased pollinator visitation and fecundity due to its utilization as a reward. We investigated the responses of bees to pollen and nectar rewards, and the effects of these rewards on pollen deposition and fecundity in the hermaphroditic succulent shrub Aloe tenuior. Self-pollinated plants failed to set fruit, but their ovules were regularly penetrated by self-pollen tubes, which uniformly failed to develop into seeds as expected from ovarian self-incompatibility (or strong early inbreeding depression. Bees consistently foraged for pollen during the morning and early afternoon, but switched to nectar in the late afternoon. As a consequence of this differential foraging, we were able to test the relative contribution to fecundity of pollen- versus nectar-collecting flower visitors. We exposed emasculated and intact flowers in either the morning or late afternoon to foraging bees and showed that emasculation reduced pollen deposition by insects in the morning, but had little effect in the afternoon. Despite the potential for self-pollination to result in ovule discounting due to late-acting self-sterility, fecundity was severely reduced in artificially emasculated plants. Although there were temporal fluctuations in reward preference, most bee visits were for pollen rewards. Therefore the benefit of providing pollen that is accessible to bee foragers outweighs any potential costs to fitness in terms of gender interference in this species.

Major grass pollen allergen Lol p 1 binds to diesel exhaust particles: implications for asthma and air pollution.

Science.gov (United States)

Knox, R B; Suphioglu, C; Taylor, P; Desai, R; Watson, H C; Peng, J L; Bursill, L A

1997-03-01

Grass pollen allergens are known to be present in the atmosphere in a range of particle sizes from whole pollen grains (approx. 20 to 55 microns in diameter) to smaller size fractions Lol p 1, immunogold labelling with specific monoclonal antibodies and a high voltage transmission electron-microscopic imaging technique. DECP are visualized as small carbon spheres, each 30-60 nm in diameter, forming fractal aggregates about 1-2 microns in diameter. Here we test our hypothesis and show by in vitro experiments that the major grass pollen allergen, Lol p 1, binds to one defined class of fine particles, DECP. DECP are in the respirable size range, can bind to the major grass pollen allergen Lol p 1 under in vitro conditions and represent a possible mechanism by which allergens can become concentrated in polluted air and thus trigger attacks of asthma.

Allergies, asthma, and pollen

Science.gov (United States)

Reactive airway - pollen; Bronchial asthma - pollen; Triggers - pollen; Allergic rhinitis - pollen ... Things that make allergies or asthma worse are called triggers. It is important to know your triggers because avoiding them is your first step toward feeling better. ...

ROPES reveals past land cover and pollen productivity estimates from single pollen records

Science.gov (United States)

Theuerkauf, Martin; Couwenberg, John

2018-04-01

Quantitative reconstructions of past vegetation cover commonly require pollen productivity estimates (PPEs). PPEs are calibrated in extensive and rather cumbersome surface-sample studies, and are so far only available for selected regions. Moreover, it may be questioned whether present-day pollen-landcover relationships are valid for palaeo-situations. We here introduce the ROPES approach that simultaneously derives PPEs and mean plant abundances from single pollen records. ROPES requires pollen counts and pollen accumulation rates (PARs, grains cm-2 year-1). Pollen counts are used to reconstruct plant abundances following the REVEALS approach. The principle of ROPES is that changes in plant abundance are linearly represented in observed PAR values. For example, if the PAR of pine doubles, so should the REVEALS reconstructed abundance of pine. Consequently, if a REVEALS reconstruction is ‘correct’ (i.e. ‘correct’ PPEs are used) the ratio ‘PAR over REVEALS’ is constant for each taxon along all samples of a record. With incorrect PPEs, the ratio will instead vary. ROPES starts from random (likely incorrect) PPEs, but then adjusts them using an optimization algorithm with the aim to minimize variation in the ‘PAR over REVEALS’ ratio across the record. ROPES thus simultaneously calculates mean plant abundances and PPEs. We illustrate the approach with test applications on nine synthetic pollen records. The results show that good performance of ROPES requires data sets with high underlying variation, many samples and low noise in the PAR data. ROPES can deliver first landcover reconstructions in regions for which PPEs are not yet available. The PPEs provided by ROPES may then allow for further REVEALS-based reconstructions. Similarly, ROPES can provide insight in pollen productivity during distinct periods of the past such as the Lateglacial. We see a potential to study spatial and temporal variation in pollen productivity for example in relation to site

Identification of sweet chesnut pollen in bee pollen pellet using using molecular analysis.

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Jana Žiarovská

2015-10-01

Full Text Available Castanea sativa posses many characteristics that are used by human for different purposes, not only as a part of the food. One of them is the utilization of the sweet chesnut pollen for its pharmacological benefits. Actually, no information about the DNA based identification of the sweet chesnut exist. Here, an identification of Castanea sativa based on the specific DNA fragment amplification is described for the first time. Sweet chesnut identification was performed in the very complex sample of bee pollen pellets that were identified as to contain sweet chesnut pollen grains by morphological analysis. First, bioinformatic analysis was performed to find a Castanea sativa conservative part of galactol synthase gene. BLAST alignment of the CDS of GolS1 gene was performed by BLASTtn against plants nucleotide sequences in the NCBI database to ensure for the specifity or existing nucleotide differences. Then, specific primers were subsequently designed and PCR amplification was performed. All the PCRs have run in duplicates for pollen pellet sample and two independent samples of Castanea sativa pure pollen. Restriction cleavage of the PCR amplified fragment was performed to confirm the specifity of the obtained PCR product with the positive confirmation as the predicted three restriction fragments were obtained that fully correspond by the length to those from virtual clevage. Restriction endonuclease Hpy166II was used in restriction cleavage analysis. Castanea sativa pollen grains were confirmed reliable in multifloral pollen pellet by PCR and this approach has the potential to be used effectively for the authentication purposes of sweet chesnut.

Calcium in pollen-pistil interaction in `Petunia hybrida Hor`. Pt. 1. Localization of Ca{sup 2+} ions in mature pollen grain using pyroantimonate and autoradiographic methods

Energy Technology Data Exchange (ETDEWEB)

Bednarska, E.; Butowt, R. [Uniwersytet Mikolaja Kopernika, Torun (Poland)

1994-12-31

The localization of Ca{sup 2+} in the mature pollen grain and the flow of these ions the somatic tissues of the anther to the pollen grains has been studied using pyroantimonate and autoradiographic methods. In the pollen grain, Ca{sup 2+} ions have been localized in the sporoderm in the cytoplasmic vesicles of probably dictyosomal origin. Calcium ions were transported into the sporoderm together with the compounds of degenerating tapetum. The material of degenerating tapetum forms pollen coat surrounding the mature pollen grains. (author). 18 refs, 9 figs.

Enhanced accuracy of the microwave field strength measurement in a CW-EPR by pulsed modulation technique

Science.gov (United States)

Rakvin, B.; Carić, D.; Kveder, M.

2018-02-01

The microwave magnetic field strength, B1, in the cavity of a conventional continuous wave electron paramagnetic resonance, CW-EPR, spectrometer was measured by employing modulation sidebands, MS, in the EPR spectrum. MS spectrum in CW-EPR is produced by applying the modulation frequency, ωrf, which exceeds the linewidth, δB, given in frequency units. An amplitude-modulated CW-EPR, AM-CW-EPR, was selected as detection method. Theoretical description of AM-CW-EPR spectrum was modified by adding Bloch-Siegert-like shift obtained by taking into account the cumulative effect of the non-resonant interactions between the driving fields and the spin system. This approach enables to enhance the precision of B1 measurement. In order to increase the sensitivity of the method when saturation effects, due to higher intensity of B1, decrease the resolution of AM-CW-EPR spectrum, detection at the second harmonic of CW-EPR has been employed.

Enhanced accuracy of the microwave field strength measurement in a CW-EPR by pulsed modulation technique.

Science.gov (United States)

Rakvin, B; Carić, D; Kveder, M

2018-02-01

The microwave magnetic field strength, B 1 , in the cavity of a conventional continuous wave electron paramagnetic resonance, CW-EPR, spectrometer was measured by employing modulation sidebands, MS, in the EPR spectrum. MS spectrum in CW-EPR is produced by applying the modulation frequency, ω rf , which exceeds the linewidth, δB, given in frequency units. An amplitude-modulated CW-EPR, AM-CW-EPR, was selected as detection method. Theoretical description of AM-CW-EPR spectrum was modified by adding Bloch-Siegert-like shift obtained by taking into account the cumulative effect of the non-resonant interactions between the driving fields and the spin system. This approach enables to enhance the precision of B 1 measurement. In order to increase the sensitivity of the method when saturation effects, due to higher intensity of B 1 , decrease the resolution of AM-CW-EPR spectrum, detection at the second harmonic of CW-EPR has been employed. Copyright © 2018 Elsevier Inc. All rights reserved.

Stress relaxation damage in K9 glass plate irradiated by 1.06μm CW laser

International Nuclear Information System (INIS)

Luo Fu; Sun Chengwei

2001-01-01

Based on the stress relaxation model in 1D planar geometry and the visco-elastic constitutive equation, the temperature and stress histories in the K9 glass samples irradiated by CW laser beams (λ = 1.06 μm) have been calculated. The results indicate that the residual tensile stress due to the stress relaxation effect during cooling after the laser radiation may be greater than the tensile fracture strength of samples, while the maximum compression stress during the laser heating is less than the requirement for compression damage. For a K9 glass window of 3 mm thickness, its damage due to the stress relaxation may be induced by a laser radiation of 0.946 MW/cm 2 for 0.2s . Therefore, the stress relaxation should be regarded as the main mechanism of damage in K9 glass windows while a CW laser beam (λ = 1.06 μm) irradiates it with large spot

Juniper Pollen Hotspots in the Southwest

Science.gov (United States)

Bunderson, L. D.; VandeWater, P.; Luvall, J.; Levetin, E.

2013-01-01

Rationale: Juniperus pollen is a major allergen in Texas, Oklahoma, and New Mexico. While the bulk of pollen may be released in rural areas, large amounts of pollen can be transported to urban areas. Major juniper species in the region include: Juniperus ashei, J. virginiana, J. pinchotii, and J. monosperma. Pollen release is virtually continuous beginning in late September with J. pinchotii and ending in May with J. monosperma. Urban areas in the region were evaluated for the potential of overlapping seasons in order to inform sensitive individuals. Methods: Burkard volumetric pollen traps were established for two consecutive spring seasons at 6 sites in northern New Mexico and 6 sites for two consecutive winter and fall seasons in Texas and Oklahoma Standard methods were used in the preparation and analysis of slides. Results: The Dallas-Fort Worth Metroplex is home to over 6 million people. It is adjacent to populations of J. pinchotii, J. virginiana, and J. ashei. Peak concentration near Dallas for J. ashei in 2011 was 5891 pollen grains/m3 in January 7th. The peak date for J. pinchotii at an upwind sampling location in San Marcos, TX was November 1, 2010 and peak for J. virginiana at a nearby station in Tulsa, OK was November 1, 2010 and peak for J. virginiana at a nearby station in Tulsa, OK was February 20, 2011. Amarillo, TX is adjacent to J. pinchotii, J. ashei, and J. monosperma populations and may be subject to juniper pollen from September through May. Conclusions: Considering the overlapping distributions of juniper trees and the overlapping temporal release of pollen, sensitive patients may benefit from avoiding hotspots.

SCC growth behavior of stainless steel weld heat-affected zone in hydrogenated high temperature water

International Nuclear Information System (INIS)

Yamada, Takuyo; Terachi, Takumi; Miyamoto, Tomoki; Arioka, Koji

2010-01-01

It is known that the SCC growth rate of stainless steels in high-temperature water is accelerated by cold-work (CW). The weld heat-affected-zone (HAZ) of stainless steels is also deformed by weld shrinkage. However, only little have been reported on the SCC growth of weld HAZ of SUS316 and SUS304 in hydrogenated high-temperature water. Thus, in this present study, SCC growth experiments were performed using weld HAZ of stainless steels, especially to obtain data on the dependence of SCC growth on (1) temperature and (2) hardness in hydrogenated water at temperatures from 250degC to 340degC. And then, the SCC growth behaviors were compared between weld HAZ and CW stainless steels. The following results have been obtained. Significant SCC growth were observed in weld HAZ (SUS316 and SUS304) in hydrogenated water at 320degC. The SCC growth rates of the HAZ are similar to that of 10% CW non-sensitized SUS316, in accordance with that the hardness of weld HAZ is also similar to that of 10% CW SUS316. Temperature dependency of SCC growth of weld HAZ (SUS316 and SUS304) is also similar to that of 10% CW non-sensitized SUS316. That is, no significant SCC were observed in the weld HAZ (SUS316 and SUS304) in hydrogenated water at 340degC. This suggests that SCC growth behaviors of weld HAZ and CW stainless steels are similar and correlated with the hardness or yield strength of the materials, at least in non-sensitized regions. And the similar temperature dependence between the HAZ and CW stainless steels suggests that the SCC growth behaviors are also attributed to the common mechanism. (author)

Crack growth of throughwall flaw in Alloy 600 tube during leak testing

International Nuclear Information System (INIS)

Bahn, Chi Bum; Majumdar, Saurin

2015-01-01

Graphical abstract: - Highlights: • A series of leak testing was conducted at a constant pressure and room temperature. • The time-dependent increase in the leak rate was observed. • The fractography revealed slip offsets and crystallographic facets. • Time-dependent plasticity at the crack tip caused the slip offsets. • Fatigue by jet/structure interaction caused the crystallographic facets. - Abstract: We examined the issue of whether crack growth in a full thickness material can occur in a leaking crack. A series of leak tests was conducted at a room temperature and constant pressure (17.3 MPa) with Alloy 600 tube specimens containing a tight rectangular throughwall axial fatigue crack. To exclude a potential pulsation effect by a high pressure pump, the test water was pressurized by using high pressure nitrogen gas. Fractography showed that crack growth in the full thickness material can occur in the leaking crack by two mechanisms: time-dependent plasticity at the crack tip and fatigue induced by jet/structure interaction. The threshold leak rate at which the jet/structure interaction was triggered was between 1.3 and 3.3 L/min for the specific heat of the Alloy 600 tube tested

Variations in pollen counts largely explained by climate and weather

Science.gov (United States)

Jung, Stephan; Damialis, Athanasios; Estrella, Nicole; Jochner, Susanne; Menzel, Annette

2017-04-01

The interaction between climate and vegetation is well studied within phenology. Climatic / weather conditions affect e.g. flowering date, length of vegetation period, start and end of the season and the plant growth. Besides phenological stages also pollen counts can be used to investigate the interaction between climate and vegetation. Pollen emission and distribution is directly influenced by temperature, wind speed, wind direction and humidity/precipitation. The objective of this project is to study daily/sub daily variations in pollen counts of woody and herbaceous plant species along an altitudinal gradient with different climatic conditions during the vegetation period. Measurements of pollen were carried out with three volumetric pollen traps installed at the altitudes 450 m a.s.l (Freising), 700 m a.s.l (Garmisch-Partenkirchen), and 2700 m a.s.l (Schneefernerhaus near Zugspitze) representing gradient from north of Munich towards the highest mountain of Germany. Airborne pollen concentrations were recorded during the years 2014-2015. The altitudinal range of these three stations accompanied by different microclimates ("space for time approach") can be used as proxy for climate change and to assess its impact on pollen counts and thus allergenic risk for human health. For example the pollen season is shortened and pollen amount is reduced at higher sites. For detailed investigations pollen of the species Plantago, Quercus, Poaceae, Cupressaceae, Cyperacea, Betula and Platanus were chosen, because those are found in appropriate quantities. In general, pollen captured in the pollen traps to a certain extent has its origin from the immediate surrounding. Thus, it mirrors local species distribution. But furthermore the distance of pollen transport is also based on (micro-) climatic conditions, land cover and topography. The pollen trap shortly below the summit of Zugspitze (Schneefernerhaus) has an alpine environment without vegetation nearby. Therefore, this

High-power pulsed and CW diode-pumped mode-locked Nd:YAG lasers

Science.gov (United States)

Marshall, Larry R.; Hays, A. D.; Kaz, Alex; Kasinski, Jeff; Burnham, R. L.

1991-01-01

The operation of both pulsed and CW diode-pumped mode-locked Nd:YAG lasers are presented. The pulsed laser produced 1.0 mJ with pulsewidths of 90 psec at 20 Hz. The CW pumped laser produced 6 W output at 1.064 microns and 3 W output at 532 nm.

Bee Pollen

Science.gov (United States)

... for nutrition; as an appetite stimulant; to improve stamina and athletic performance; and for premature aging, premenstrual ... use bee pollen as a general tonic, to increase urine flow, and for alcohol intoxication. Bee pollen ...

Use of higher plants as screens for toxicity assessment.

Science.gov (United States)

Kristen, U

1997-01-01

This review deals with the use of entire plants, seedlings, cell suspension cultures and pollen tubes for the estimation of potential toxicity in the environment, and for risk assessment of chemicals and formulations of human relevance. It is shown that the roots of onions and various crop seedlings, as well as in vitro growing pollen tubes of some mono- and dicotyledonous plants, are most frequently used to obtain toxicity data by determination of root and tube growth inhibition. Both roots and pollen tubes are chloroplast free, non-photosynthetic systems and, therefore, with regard to their cytotoxic reactions are closer to vertebrate tissues and cells than are chloroplast-containing plant organs. Root tips and anthers of flower buds are shown to be applicable to genotoxicity screening by microscopic analysis of mitotic or meiotic aberrations during cell division or microspore development, respectively. The processes of mitosis and meiosis are similar in plants and animals. Therefore, meristematic and sporogenic tissues of plants generally show patterns of cytotoxic response similar to those of embryogenic and spermatogenic tissues of vertebrates. The suitability of root tips, cell suspensions and pollen tubes for the investigation of mechanisms of toxic action and for the analysis of structure-activity relationships is also demonstrated. Two plant-based assays, the Allium test and the pollen tube growth test, both currently being evaluated alongside with established mammalian in vivo and in vitro protocols, are emphasized with regard to their potential use as alternatives to animal in vivo toxicity tests. For both assays, preliminary results indicate that the tips of growing roots and the rapidly elongating pollen tubes of certain higher plant species are as reliable as mammalian cell lines for detecting basal cytotoxicity. It is suggested that seeds and pollen grains, in particular, provide easily storable and convenient systems for inexpensive, relatively

Evaluation of reproductive barriers contributes to the development of novel interspecific hybrids in the Kalanchoë genus

DEFF Research Database (Denmark)

Kuligowska, Katarzyna; Lütken, Henrik Vlk; Christensen, Brian

2015-01-01

BackgroundInterspecific hybridization is a useful tool in ornamental breeding to increase genetic variability and introduce new valuable traits into existing cultivars. The successful formation of interspecific hybrids is frequently limited by the presence of pre- and post-fertilization barriers....... In the present study, we investigated the nature of hybridization barriers occurring in crosses between Kalancho? species and evaluated possibilities of obtaining interspecific hybrids.ResultsThe qualitative and quantitative analyses of pollen tube growth in situ were performed following intra- and interspecific...... pollinations. They revealed occurrence of pre-fertilization barriers associated with inhibition of pollen germination on the stigma and abnormal growth of pollen tubes. Unilateral incongruity related to differences in pistil length was also observed. The pollen quality was identified as a strong factor...

Molecular Cloning and Expression of Pro J 1: A New Allergen of Prosopis Juliflora Pollen.

Science.gov (United States)

Dousti, Fatemeh; Assarehzadegan, Mohammad-Ali; Morakabati, Payam; Khosravi, Gholam Reza; Akbari, Bahareh

2016-04-01

Pollen from mesquite (Prosopis juliflora) is one of the important causes of immediate hypersensitivity reactions in the arid and semi-arid regions of the world. The aim of present study is to produce and purify the recombinant form of allergenic Ole e 1-like protein from the pollen of this allergenic tree. Immunological and cross-inhibition assays were performed for the evaluation of IgE-binding capacity of purified recombinant protein. For molecular cloning, the coding sequence of the mesquite Ole e 1-like protein was inserted into pTZ57R/T vector and expressed in Escherichia coli using the vector pET-21b(+). After purification of the recombinant protein, its immunoreactivity was analysed by in vitro assays using sera from twenty one patients with an allergy to mesquite pollen. The purified recombinant allergen was a member of Ole e 1-like protein family and consisted of 150 amino acid residues, with a predicted molecular mass of 16.5 kDa and a calculated isoelectric point (pI) of 4.75. Twelve patients (57.14%) had significant specific IgE levels for this recombinant allergen. Immunodetection and inhibition assays indicated that the purified recombinant allergen might be the same as that in the crude extract. Herein, we introduce an important new allergen from P. juliflora pollen (Pro j 1), which is a member of the Ole e 1-like protein family and exhibits significant identity and similarity to other allergenic members of this family.

Oxide growth and exfoliation of materials in steam tubing. Lesson 9

Energy Technology Data Exchange (ETDEWEB)

Dooley, R. Barry; Bursik, Albert

2011-04-15

University 101 courses are typically designed to help incoming first-year undergraduate students to adjust to the university, develop a better understanding of the college environment, and acquire essential academic success skills. Why are we offering a special Boiler and HRSG Tube Failures PPChem 101? The answer is simple, yet very conclusive: - There is a lack of knowledge on the identification of tube failure mechanisms and for the implementation of adequate counteractions in many power plants, particularly at industrial power and steam generators. - There is a lack of knowledge to prevent repeat tube failures. The vast majority of BTF/HTF have been, and continue to be, repeat failures. It is hoped that the information about the failure mechanisms of BTF supplied in this course will help to put plant engineers and chemists on the right track. The major goal of this course is the avoidance of repeat BTF. This ninth lesson is focused on Oxide Growth and Exfoliation of Materials in Steam Tubing. (orig.)

1-W quasi-cw near-diffraction-limited semiconductor laser pumped optically by a fibre-coupled diode bar

OpenAIRE

Dhanjal, S.; Hoogland, S.; Roberts, J.S.; Hayward, R.A.; Clarkson, W.A.; Tropper, Anne

2000-01-01

We describe a diode-bar-pumped vertical-external-cavity surface-emitting semiconductor laser, which in quasi-cw operation emitted a peak power of >1 W at 1020 nm in a circular, near diffraction-limited beam.

Mutation in SUMO E3 ligase, SIZ1, disrupts the mature female gametophyte in Arabidopsis

KAUST Repository

Ling, Yu

2012-01-09

Female gametophyte is the multicellular haploid structure that can produce embryo and endosperm after fertilization, which has become an attractive model system for investigating molecular mechanisms in nuclei migration, cell specification, cell-to-cell communication and many other processes. Previous reports found that the small ubiquitin-like modifier (SUMO) E3 ligase, SIZ1, participated in many processes depending on particular target substrates and suppression of salicylic acid (SA) accumulation. Here, we report that SIZ1 mediates the reproductive process. SIZ1 showed enhanced expression in female organs, but was not detected in the anther or pollen. A defect in the siz1-2 maternal source resulted in reduced seed-set regardless of high SA concentration within the plant. Moreover, aniline blue staining and scanning electron microscopy revealed that funicular and micropylar pollen tube guidance was arrested in siz1-2 plants. Some of the embryo sacs of ovules in siz1-2 were also disrupted quickly after stage FG7. There was no significant affects of the siz1-2 mutation on expression of genes involved in female gametophyte development- or pollen tube guidance in ovaries. Together, our results suggest that SIZ1 sustains the stability and normal function of the mature female gametophyte which is necessary for pollen tube guidance. © 2012 Ling et al.

Pollen rain and pollen representation across a forest-páramo ecotone in northern Ecuador

NARCIS (Netherlands)

Moscol Olivera, M.; Duivenvoorden, J.F.; Hooghiemstra, H.

2009-01-01

Modern pollen spectra were studied in forest and páramo vegetation from the Guandera area, northern Ecuador. Pollen representation was estimated by comparing the presence of plant taxa from a recent vegetation survey with the pollen spectra in moss polsters and pollen traps. In total, 73 pollen taxa

EXO70C2 is a key regulatory factor for optimal tip growth of pollen

KAUST Repository

Synek, Lukas; Vukasinovic, Nemanja; Kulich, Ivan; Hala, Michal; Aldorfova, Klara; Fendrych, Matyas; Zarsky, Viktor

2017-01-01

paralogs. Out of 23 Arabidopsis EXO70 isoforms, we analyzed seven isoforms expressed in pollen. Genetic and microscopic analyses of single mutants in EXO70A2, C1, C2, F1, H3, H5, and H6 genes revealed that only a loss-of-function EXO70C2 allele resulted

Exocyst SEC3 and Phosphoinositides Define Sites of Exocytosis in Pollen Tube Initiation and Growth

Czech Academy of Sciences Publication Activity Database

Bloch, D.; Pleskot, Roman; Pejchar, Přemysl; Potocký, Martin; Trpkošová, Pavlína; Cwiklik, Lukasz; Vukašinović, Nemanja; Sternberg, H.; Yalovsky, S.; Žárský, Viktor

2016-01-01

Roč. 172, č. 2 (2016), s. 980-1002 ISSN 0032-0889 R&D Projects: GA ČR GA13-19073S Institutional support: RVO:61389030 ; RVO:61388955 Keywords : polar cell-growth * arabidopsis-thaliana * plasma-membrane * vesicle trafficking * affects endocytosis * subunit sec3 * force-field * tip growth * complex * tobacco Subject RIV: EB - Genetics ; Molecular Biology; CF - Physical ; Theoretical Chemistry (UFCH-W) Impact factor: 6.456, year: 2016

Weak Static and Extremely Low Frequency Magnetic Fields Affect In Vitro Pollen Germination

Directory of Open Access Journals (Sweden)

Lucietta Betti

2011-01-01

Full Text Available This study concerns the effects of a weak static magnetic field (MF at 10 μT oriented downward, combined with a 16-Hz sinusoidal MF (10 μT, on in vitro pollen germination of kiwifruit (Actinidia deliciosa. Extremely low frequency magnetic field (ELF-MF exposure was carried out by a signal generator unit connected to a copper wire solenoid, inside which samples where placed. Two different kinds of treatment were performed: direct and indirect. In the direct treatment, pollen samples were directly exposed during rehydration, germination, or both. In the indirect treatment, the pollen growth medium was prepared with water aliquots (at standard temperature of 20°C and pH = 6.74 that were exposed before use for 8 or 24 h. The main purpose of our research was to identify a biological marker (in vitro pollen germination in a stressing growth medium without Ca2+ susceptible to the effects of direct or indirect ELF-MF exposure. The working variable was the pollen germination rate, as detected blind after 3 h 30 min by an Axioplan microscope. A directionally consistent recovery of germination percentage was observed both for direct exposure (during germination and both rehydration and germination phases and water-mediated exposure (with water exposed for 24 h and immediately used. Our results suggest that the ELF-MF treatment might partially remove the inhibitory effect caused by the lack of Ca2+ in the culture medium, inducing a release of internal Ca2+ stored in the secretory vesicles of pollen plasma membrane. Although preliminary, findings seem to indicate the in vitro pollen performance as adequate to study the effects of ELF-MFs on living matter.

How honey bees carry pollen

Science.gov (United States)

Matherne, Marguerite E.; Anyanwu, Gabriel; Leavey, Jennifer K.; Hu, David L.

2017-11-01

Honey bees are the tanker of the skies, carrying thirty percent of their weight in pollen per foraging trip using specialized orifices on their body. How do they manage to hang onto those pesky pollen grains? In this experimental study, we investigate the adhesion force of pollen to the honeybee. To affix pollen to themselves, honey bees form a suspension of pollen in nectar, creating a putty-like pollen basket that is skewered by leg hairs. We use tensile tests to show that the viscous force of the pollen basket is more than ten times the honeybee's flight force. This work may provide inspiration for the design of robotic flying pollinators.

Correlation between airborne Olea europaea pollen concentrations and levels of the major allergen Ole e 1 in Córdoba, Spain, 2012-2014

Science.gov (United States)

Plaza, M. P.; Alcázar, P.; Galán, C.

2016-12-01

Olea europaea L. pollen is the second-largest cause of pollinosis in the southern Iberian Peninsula. Airborne-pollen monitoring networks provide essential data on pollen dynamics over a given study area. Recent research, however, has shown that airborne pollen levels alone do not always provide a clear indicator of actual exposure to aeroallergens. This study sought to evaluate correlations between airborne concentrations of olive pollen and Ole e 1 allergen levels in Córdoba (southern Spain), in order to determine whether atmospheric pollen concentrations alone are sufficient to chart changes in hay fever symptoms. The influence of major weather-related variables on local airborne pollen and allergen levels was also examined. Monitoring was carried out from 2012 to 2014. Pollen sampling was performed using a Hirst-type sampler, following the protocol recommended by the Spanish Aerobiology Network. A multi-vial cyclone sampler was used to collect aeroallergens, and allergenic particles were quantified by ELISA assay. Significant positive correlations were found between daily airborne allergen levels and atmospheric pollen concentrations, although there were occasions when allergen was detected before and after the pollen season and in the absence of airborne pollen. The correlation between the two was irregular, and pollen potency displayed year-on-year variations and did not necessarily match pollen-season-intensity.

Is Eucalyptus Cryptically Self-incompatible?

Science.gov (United States)

Horsley, Tasmien N; Johnson, Steven D

2007-12-01

The probability that seeds will be fertilized from self- versus cross-pollen depends strongly on whether plants have self-incompatibility systems, and how these systems influence the fate of pollen tubes. In this study of breeding systems in Eucalyptus urophylla and Eucalyptus grandis, epifluorescence microscopy was used to study pollen tube growth in styles following self- and cross-pollinations. Pollen tubes from self-pollen took significantly longer than those from cross-pollen to grow to the base of the style in both E. urophylla (120 h vs. 96 h) and E. grandis (96 h vs. 72 h). In addition, both species exhibited reduced seed yields following self-pollination compared with cross-pollination. The present observations suggest that, in addition to a late-acting self-incompatibility barrier, cryptic self-incompatibility could be a mechanism responsible for the preferential out-crossing system in these two eucalypt species.

Design and performance verification of advanced multistage depressed collectors. [traveling wave tubes for ECM

Science.gov (United States)

Kosmahl, H.; Ramins, P.

1975-01-01

Design and performance of a small size, 4-stage depressed collector are discussed. The collector and a spent beam refocusing section preceding it are intended for efficiency enhancement of octave bandwidth, high CW power traveling wave tubes for use in ECM.

Pollen Forecast and Dispersion Modelling

Science.gov (United States)

Costantini, Monica; Di Giuseppe, Fabio; Medaglia, Carlo Maria; Travaglini, Alessandro; Tocci, Raffaella; Brighetti, M. Antonia; Petitta, Marcello

2014-05-01

Bologna, Italy). With pollen and meteorological dataset was created a provisional model for Poaceae. A PLSDA (Partial Least Squares Discriminant Analysis) approach was used in order to predict Poaceae pollen critical concentration (Brighetti et al. 2013) To preserve spatial correlation between pollens and PM10, we choose a Multiavariate Linear Spatial Interpolation Method to quantify pollen concentration in function of PM10, wind, rain and temperature. A test and validation procedure have been conducted to estimate the error associated to the pollen concentration. Validation for the year 2012 shows a good agreement between measured and estimated data , in each area depending of orography and of road traffic (r >0.83, 1%< RRMSE <5% ). This study aims to be a added value to agro-meteorological data in a different branch from the classic sector of defence and of crop production, emphasizing the importance of monitoring and forecast the pollen dispersal in urban areas, evaluated its effect on health and quality of life. In the health area the combined analysis between climate, pollution and dispersal of pollen allows to realize significant operational tools and to develop a reference for subsequent implementations.

Unique and cross-reactive T cell epitope peptides of the major Bahia grass pollen allergen, Pas n 1.

Science.gov (United States)

Etto, Tamara; de Boer, Carmela; Prickett, Sara; Gardner, Leanne M; Voskamp, Astrid; Davies, Janet M; O'Hehir, Robyn E; Rolland, Jennifer M

2012-01-01

Bahia grass pollen (BaGP) is a major cause of allergic rhinitis. Subcutaneous allergen-specific immunotherapy is effective for grass pollen allergy, but is unsuitable for patients with moderate to severe asthma due to the risk of anaphylaxis. T cell-reactive but IgE nonreactive peptides provide a safer treatment option. This study aimed to identify and characterize dominant CD4(+) T cell epitope peptides of the major BaGP allergen, Pas n 1. Pas n 1-specific T cell lines generated from the peripheral blood of BaGP-allergic subjects were tested for proliferative and cytokine response to overlapping 20-mer Pas n 1 peptides. Cross-reactivity to homologous peptides from Lol p 1 and Cyn d 1 of Ryegrass and Bermuda grass pollen, respectively, was assessed using Pas n 1 peptide-specific T cell clones. MHC class II restriction of Pas n 1 peptide T cell recognition was determined by HLA blocking assays and peptide IgE reactivity tested by dot blotting. Three Pas n 1 peptides showed dominant T cell reactivity; 15 of 18 (83%) patients responded to one or more of these peptides. T cell clones specific for dominant Pas n 1 peptides showed evidence of species-specific T cell reactivity as well as cross-reactivity with other group 1 grass pollen allergens. The dominant Pas n 1 T cell epitope peptides showed HLA binding diversity and were non-IgE reactive. The immunodominant T cell-reactive Pas n 1 peptides are candidates for safe immunotherapy for individuals, including those with asthma, who are allergic to Bahia and possibly other grass pollens. Copyright © 2012 S. Karger AG, Basel.

Pollen viability and membrane lipid composition

NARCIS (Netherlands)

Bilsen, van D.G.J.L.

1993-01-01

In this thesis membrane lipid composition is studied in relation to pollen viability during storage. Chapter 1 reviews pollen viability, membranes in the dry state and membrane changes associated with cellular aging. This chapter is followed by a study of age-related changes in phospholipid

Insecticide use in hybrid onion seed production affects pre- and postpollination processes.

Science.gov (United States)

Gillespie, Sandra; Long, Rachael; Seitz, Nicola; Williams, Neal

2014-02-01

Research on threats to pollination service in agro-ecosystems has focused primarily on the negative impacts of land use change and agricultural practices such as insecticide use on pollinator populations. Insecticide use could also affect the pollination process, through nonlethal impacts on pollinator attraction and postpollination processes such as pollen viability or pollen tube growth. Hybrid onion seed (Allium cepa L., Alliaceae) is an important pollinator-dependent crop that has suffered yield declines in California, concurrent with increased insecticide use. Field studies suggest that insecticide use reduces pollination service in this system. We conducted a field experiment manipulating insecticide use to examine the impacts of insecticides on 1) pollinator attraction, 2) pollen/stigma interactions, and 3) seed set and seed quality. Select insecticides had negative impacts on pollinator attraction and pollen/stigma interactions, with certain products dramatically reducing pollen germination and pollen tube growth. Decreased pollen germination was not associated with reduced seed set; however, reduced pollinator attraction was associated with lower seed set and seed quality, for one of the two female lines examined. Our results highlight the importance of pesticide effects on the pollination process. Overuse may lead to yield reductions through impacts on pollinator behavior and postpollination processes. Overall, in hybrid onion seed production, moderation in insecticide use is advised when controlling onion thrips, Thrips tabaci, on commercial fields.

Induced mutants of Cox's Orange Pippin apple with apparent increased self-compatibility. Pt. 2

International Nuclear Information System (INIS)

Church, R.M.; Lacey, C.N.D.; Richardson, P.

1982-01-01

Fruit set on clones of Cox's Orange Pippin apple which had been produced by gamma-irradiation, and found in a previous trial to crop when isolated from the pollen of other cultivars, was compared after open or hand-pollination. Some clones set more fruit than the unirradiated control trees when open pollinated or when hand-pollinated with pollen from the same tree or control Cox trees. Pollen from some mutant clones also improved set on standard Cox (EMLA). Estimates of the numbers of pollen tubes reaching the base of the style indicated that the increased set was due to enhanced tube growth. (orig.)

Nature's Notebook Provides Phenology Observations for NASA Juniper Phenology and Pollen Transport Project

Science.gov (United States)

Luval, J. C.; Crimmins, T. M.; Sprigg, W. A.; Levetin, E.; Huete, A.; Nickovic, S.; Prasad, A.; Vukovic, A.; VandeWater, P. K.; Budge, A. M.;

Quality of durable cookies enriched with rape bee pollen

Directory of Open Access Journals (Sweden)

Miriam Solgajová

2014-03-01

Full Text Available The objective of this study was to enrich durable cookies with different additions of rape (Brassica napus var. napus bee pollen to increase nutritional properties of cookie samples and to improve technological and sensorial properties as well. Bee pollen is an important raw material due to its nutritional and functional properties. Cookie samples were prepared by substituting wheat flour with rape bee pollen in the amount of 16 % (1 g of bee pollen per cookie and 32 % (2 g of bee pollen per cookie using bee pollen from two localities Lenártovce and Nové Zámky. In baked samples beside sensory properties also chemical parameters and technological parameters of cookies were evaluated. It was found out that with the gradual addition of rape bee pollen the amount of ash content increased and the highest ash content was analysed in variants II and IV (0.71 and 0.77 % using 32 % addition of rape bee pollen. In terms of reducing sugars, addition of bee pollen caused that the content of reducing sugars in the products increased slightly. The highest reducing sugar content was determined in variant II. (24.59 %. On the other hand amount of crude protein the most considerably raised by addition of 2 g of pollen per cookie. The highest content of crude protein was analysed in variants II and IV (8.72 and 9.00 %. From the results of a linear models in which the dependent variables were the ash, crude protein and moisture it was determined the significant effect (p <0.05 only of the pollen addition. In the case of the model with the dependent variable reducing sugars it was found out significant effect (p<0.0001 of pollen addition and locality and their interactions. With the gradual addition of bee pollen values of technological parameters such as diameter and weight of cookies increased and thickness of products decreased. Based on sensory scores using a 9-point Hedonic scale the best sensorial acceptability (7.4 was found in variant I (1 g of bee

Evaluation of pollen collected by honey bee, Apis mellifera L. colonies at Fayoum Governorate, Egypt. Part 1: Botanical origin

Directory of Open Access Journals (Sweden)

Abdel-Halim M. Ismail

2013-06-01

Full Text Available The present work is the 1st part of 3-part study carried out at Fayoum Governorate, Egypt to evaluate the pollen species collected by honey bee, Apis mellifera L., colonies during two successive years, 2009 and 2010. Obtained results showed that, in 2009, total amount of trapped pollen (fresh weight was 2354.89 g/colony/year (mean 588.72 g/colony/season, with peaks in summer and spring, while declined in autumn and winter. Correlation between mean maximum and minimum temperatures and weekly pollen weights was highly positive, while it was insignificant for relative humidity. In 2010, total amount of trapped pollen decreased to 1635.36 g/colony/year (mean 408.84 g/colony/season. The largest amounts were collected in summer followed by winter then spring, while least ones were in autumn. Correlation was highly positive between weekly mean of pollen weights and maximum temperature, while it was insignificant for minimum temperature or relative humidity. There were 24 plant species of 16 botanical families from which bees collected pollen. These sources were ranked according to their predominant quantities in the 1st and 2nd years by two numbers, respectively as the following: sesame 1 and 1, maize 2 and 2, clover 3 and 7, sunflower 4 and 8, wild mustard 5 and 3, casuarina 6 and 13, olive 7 and 11, eucalyptus 8 and 4, pumpkin 9 and 9, cocklebur 10 and 5, date palm 11 and 10, chamomile 12 and 12, field bindweed 13 and 6, pepper 14 and 20, coriander 15 and 16, acacia 16 and 24, citrus 17 and 0, marigold 18 and 0, common red 19 and 17, Christ’s thorn 20 and 22, tooth pick 21 and 21, brood bean 22 and 15, belladonna 23 and 23, pea 0 and 14, marjoram 0 and 18 and fennel 0 and 19. The 1st five plants seem to be the main pollen sources for honey bee colonies and consequently pollen producing during the whole year in the tested region. These sources represented 75.61% and 66.95% of the total annual yield in the two surveyed years, respectively.

PollenCALC: Software for estimation of pollen compatibility of self-incompatible allo- and autotetraploid species

DEFF Research Database (Denmark)

Aguirre, Andrea A; Wollenweber, Bernd; Frei, Ursula K

2012-01-01

available for predicting pollen haplotype frequencies and pollen compatibility in tetraploid species. Results PollenCALC is a software tool written in C++ programming language that can predict pollen compatibility percentages for polyploid species with a two-locus (S, Z) self-incompatibility system...

Polystyrene tube radioimmunoabsorbent assay for IgE anti-penicillin antibody

International Nuclear Information System (INIS)

Urena, V.; Delgado, R.G.; Daroca, P.; Lahoz, C.

1977-01-01

A radioimmunoassay technique has been developed based on the binding capacity of polystyrene for proteins. The method was tested on sera from thirteen patients with suspected penicillin allergy, five healthy controls, and three patients with seasonal pollen reactions. The results were compared with those obtained by the radio-allergoabsorbent method (RAST) and with basophil degranulation by penicillin. A penicillin/ovalbumin conjugate (pen-OA) was prepared and polystyrene tubes were incubated with pen-OA, 3% human serum albumin to block free sites, 1/10 dilution of test serum, anti-IgE antiserum specific for epsilon chains, and 125 I-IgE. The tubes were washed after the incubation period and the empty tubes counted in a γ scintillation counter. The specificity of the method was tested by an inhibition assay. The technique seemed more sensitive than the RAST method, the results were reproducible and in general showed good correlation with those of the RAST method. This polystyrene tube radioimmunoabsorbent method therefore provides a simple, specific and sensitive diagnostic technique for penicillin allergy. (U.K)

Occupational Allergy to Peach (Prunus persica) Tree Pollen and Potential Cross-Reactivity between Rosaceae Family Pollens.

Science.gov (United States)

Jiang, Nannan; Yin, Jia; Mak, Philip; Wen, Liping

2015-10-01

Orchard workers in north China are highly exposed to orchard pollens, especially peach and other Rosaceae family pollens during pollination season. The aim of this study was to investigate whether occupational allergy to peach tree pollen as a member of Rosaceae family is IgE-mediated and to evaluate the cross-reactivity among Rosaceae family pollens. Allergen skin test and conjunctival challenge test were performed; enzyme linked immune-sorbent assay (ELISA), inhibiting ELISA, western immunoblotting and inhibiting western immunoblotting were done with Rosaceae family orchard pollens, including peach, apricot, cherry, apple and pear tree pollens. Mass spectrometry was also performed to probe the main allergen component and cross-reactive protein. Sensitizations to peach pollen were found in both skin test and conjunctival challenge in the patients. Serum specific IgE to three pollens (peach, apricot and cherry) were detected through ELISA. When peach pollen used as solid phase, ELISA inhibition revealed other four kinds of pollens capable of inducing partial to strong inhibitions (45% to 87%), with the strongest inhibition belonging to apricot pollen (87%). Western blotting showed predominant IgE binding to a 20 KD protein among these pollens, which appeared to be a cross-reactive allergen component through western blotting inhibition. It was recognized as a protein homologous to glutathione s-transferase 16 from Arabidopsis thaliana. Peach and other Rosaceae family tree pollen may serve as a potential cause of IgE mediated occupational respiratory disease in orchard workers in north China.

Seasonal and intradiurnal variation of airborne pollen concentrations in Bodrum, SW Turkey.

Science.gov (United States)

Tosunoglu, Aycan; Bicakci, Adem

2015-04-01

An aeropalynological study was performed in Bodrum, the famous tourism center in southwestern Turkey with a Hirst-type volumetric 7-day pollen and spore trap for 2 years (2007-2008). In Bodrum, 25,099 pollen grains as a mean value belonging to 41 taxa were recorded annually during the study period, and pollen grains from woody plant taxa had the largest atmospheric contribution of 86.99% and 24 taxa. However, 17 herbaceous plant taxa constituted 12.82% of the annual total pollen count, and 0.19% were unidentified. An average annual pollen index of 22.66% was recorded in March, despite differences from year to year. The highest pollen variability of 34 taxa was recorded in April and May. Predominant pollen types belonged to Cupressaceae/Taxaceae (42.73%), Quercus (15.95%), Pinus (9.78%), Olea europaea (9.04%), Poaceae (5.50%), Betula (1.82%), Pistacia (1.74%), Morus (1.72%), Urticaceae (1.46%), and Plantago (1.28%) and generated 91.03 of the annual total. In total, 32.59% of the mean annual total pollen index was recorded in the morning, and less pollen was recorded in the evening (18.71%). Maximum pollen concentration was recorded between 11:00 and 12:00 a.m.

Nutritional aspects of honey bee-collected pollen and constraints on colony development in the eastern Mediterranean.

Science.gov (United States)

Avni, Dorit; Hendriksma, Harmen P; Dag, Arnon; Uni, Zehava; Shafir, Sharoni

2014-10-01

Pollen is the main protein and lipid source for honey bees (Apis mellifera), and nutritionally impoverished landscapes pose a threat to colony development. To determine colony nutritional demands, we analyzed a yearly cycle of bee-collected pollen from colonies in the field and compared it to colony worker production and honey bee body composition, for the first time in social insects. We monitored monthly bee production in ten colonies at each of seven sites throughout Israel, and trapped pollen bi-monthly in five additional colonies at each of four of these sites. Pollen mixtures from each sampling date and site were analyzed for weight, total protein, total fatty acids (FAs), and FA composition. Compared to more temperate climates, the eastern Mediterranean allows a relatively high yearly colony growth of ca. 300,000-400,000 bees. Colonies at higher elevation above sea level showed lower growth rates. Queen egg-laying rate did not seem to limit growth, as peaks in capped brood areas showed that queens lay a prolific 2000 eggs a day on average, with up to 3300 eggs in individual cases. Pollen uptake varied significantly among sites and seasons, with an overall annual mean total 16.8kg per colony, containing 7.14kg protein and 677g fat. Overall mean pollen protein content was high (39.8%), and mean total FA content was 3.8%. Production cost, as expressed by the amount of nutrient used per bee, was least variable for linoleic acid and protein, suggesting these as the best descriptive variables for total number of bees produced. Linolenic acid levels in pollen during the autumn were relatively low, and supplementing colonies with this essential FA may mitigate potential nutritional deficiency. The essentiality of linoleic and linolenic acids was consistent with these FAs' tendency to be present at higher levels in collected pollen than in the expected nutrients in bee bodies, demonstrating a well-developed adjustment between pollinator nutritional demands and the

Design and construction of tetrode tube modulator for high power electron accelerator

Directory of Open Access Journals (Sweden)

A M Poursaleh

2015-09-01

Full Text Available In this paper, a high power tetrode tube (TH781-200kW, cw modulator is designed and implemented. This modulator is used for a part of RF system of the first Iranian high power electron accelerator project with similar structure to Rhodotron accelerator. Regarding to the level of sensitive and importance of TH781 tube the modulator system designed with high accuracy. So beside of power supplies design the control circuits for protection of the tube have been considered. The results of test and operation of this system that have been constructed in Iran for fist time is very satisfactory

Diode-pumped CW Nd:SGG laser at 1070 nm

International Nuclear Information System (INIS)

Liang, W; Sun, G C; Yu, X; Li, B Z; Jin, G Y

2011-01-01

We report for the first time (to our knowledge) a diode-pumped Nd:SGG laser emitting at 1070 nm. A power of 1.23 W at 1070 nm has been achieved in continuous-wave (CW) operation with a fiber-coupled laser diode emitting 18.2 W at 806 nm. Intracavity second-harmonic generation (SHG) in CW mode has also been demonstrated with a power of 328 mW at 535 nm by using a LiB 3 O 5 (LBO) nonlinear crystal. The green beam quality factor M 2 was less than 1.22. The green power stability was less 2.5% in 4 hour

Eighth CW and High Average Power RF Workshop

CERN Document Server

2014-01-01

We are pleased to announce the next Continuous Wave and High Average RF Power Workshop, CWRF2014, to take place at Hotel NH Trieste, Trieste, Italy from 13 to 16 May, 2014. This is the eighth in the CWRF workshop series and will be hosted by Elettra - Sincrotrone Trieste S.C.p.A. (www.elettra.eu). CWRF2014 will provide an opportunity for designers and users of CW and high average power RF systems to meet and interact in a convivial environment to share experiences and ideas on applications which utilize high-power klystrons, gridded tubes, combined solid-state architectures, high-voltage power supplies, high-voltage modulators, high-power combiners, circulators, cavities, power couplers and tuners. New ideas for high-power RF system upgrades and novel ways of RF power generation and distribution will also be discussed. CWRF2014 sessions will start on Tuesday morning and will conclude on Friday lunchtime. A visit to Elettra and FERMI will be organized during the workshop. ORGANIZING COMMITTEE (OC): Al...

The clinical relevance of sensitization to pollen-related fruits and vegetables in unselected pollen-sensitized adults

DEFF Research Database (Denmark)

Osterballe, M.; Hansen, T.K.; Mørtz, Charlotte G

2005-01-01

BACKGROUND: Previous studies have described cross-reactivity between fresh fruits, vegetables and pollen. However, no data demonstrates the clinical relevance of sensitization to pollen-related fruits and vegetables in unselected pollen-sensitized adults with and without symptoms in the pollen...... season. OBJECTIVE: The aim of this study was to estimate the clinical relevance of sensitization to pollen-related fruits and vegetables in unselected pollen-sensitized adults and to examine the diagnostic value of skin-prick test (SPT), histamine release and specific IgE compared with the outcome...... of oral challenge. METHODS: In total, 936 unselected adults (female : male 479 : 457, median age 33.7 years) were examined for pollen sensitization and clinical cross-reactivity with pollen-related fruits and vegetables by questionnaire, SPT, histamine release, specific IgE and oral challenge. RESULTS...

Allergy immunotherapy with a hypoallergenic recombinant birch pollen allergen rBet v 1-FV in a randomized controlled trial.

Science.gov (United States)

Klimek, Ludger; Bachert, Claus; Lukat, Karl-Friedrich; Pfaar, Oliver; Meyer, Hanns; Narkus, Annemie

2015-01-01

Pollen extracts and chemically modified allergoids are used successfully in allergen immunotherapy (AIT). Recombinant extracts offer potential advantages with respect to pharmaceutical quality, standardization and dosing. A hypoallergenic recombinant folding variant of the major birch pollen allergen (rBet v 1-FV) was compared with an established native birch preparation. A pre-seasonal, randomized, actively controlled phase II study was performed in birch pollen allergic rhino-conjunctivitis with or without asthma, GINA I/ II. 51 patients (24 rBet v 1-FV, 27 native extract) started therapy with subcutaneous allergen immunotherapy (SCIT). Primary end-point was a combined symptom medication score (SMS), changes in nasal provocation test, visual rating score and specific antibody responses secondary end-points. After one pre-seasonal treatment course the combined SMS was 5.86 (median; IQR: 14.02) for the rBet v 1-FV group versus 12.40 (median; IQR: 9.32) for the comparator during the three weeks pollen season (p = 0.330). After treatment in the second year, scores were 3.00 (median; IQR: 6.50) and 2.93 (4.86) respectively. Allergen tolerance in a nasal provocation test improved to a comparable extent in both groups. Significant increases in birch pollen-specific IgG1 and IgG4 were observed in both treatment groups following the first treatment phase and remained significantly raised until the end of the study. In this first in man, proof of concept phase II trial no statistical difference between rBet v 1-FV and an established natural pollen extract could be observed. rBet v 1-FV could be administered in higher doses than the native protein with no increase in adverse effects. The study was registered in clinicalTrials.gov (NCT00266526).

Studies on the comparison of pollen morphology and viability of four naturally distributed and commercial varieties of anemone coronaria L

International Nuclear Information System (INIS)

Candan, F.

2015-01-01

The present study presents a comparison of the pollen morphology and viability of naturally distributed four varieties of Anemone coronaria L. These are A. coronaria var. coccinea (Jord.) Burn, A. coronaria var. rosea (Hanry) Batt, A. coronaria var. cyanea, A. coronaria var. alba Goaty and Pens) and its commercial cultivars. The four varieties were collected from areas near the road side along the Kirkagac-Soma highway in the State of Manisa. The commercial cultivars were obtained from the commercial flower growers in the Urla region of zmir. Pollen viability levels decreased in all commercial cultivars of A. coronaria. The highest reduction in pollen viability was recorded in A. coronaria pink cultivars of de Caen group. The general pollen type is prolate spheroidal in all pure forms, but there are some pollen morphological features which were not observed in the natural ones, although encountered in all commercial cultivars. On the other hand, various non-viable pollen types like wrinkled pollens, with abnormally shaped pollens or pollinia were found in the commercial cultivars. It was concluded that pesticides used to produce more flowers with rapid growth are the major cause for his reduction. Another reason could be the use of tetraploid F1 hybrids of A. coronaria cultivars of de Caen group as commercial samples. (author)

Slit/Robo1 signaling regulates neural tube development by balancing neuroepithelial cell proliferation and differentiation

Energy Technology Data Exchange (ETDEWEB)

Wang, Guang; Li, Yan; Wang, Xiao-yu [Key Laboratory for Regenerative Medicine of The Ministry of Education, Department of Histology and Embryology, School of Medicine, Jinan University, Guangzhou 510632 (China); Han, Zhe [Institute of Vascular Biological Sciences, Guangdong Pharmaceutical University, Guangzhou 510224 (China); Chuai, Manli [College of Life Sciences Biocentre, University of Dundee, Dundee DD1 5EH (United Kingdom); Wang, Li-jing [Institute of Vascular Biological Sciences, Guangdong Pharmaceutical University, Guangzhou 510224 (China); Ho Lee, Kenneth Ka [Stem Cell and Regeneration Thematic Research Programme, School of Biomedical Sciences, Chinese University of Hong Kong, Shatin (Hong Kong); Geng, Jian-guo, E-mail: jgeng@umich.edu [Institute of Vascular Biological Sciences, Guangdong Pharmaceutical University, Guangzhou 510224 (China); Department of Biologic and Materials Sciences, University of Michigan School of Dentistry, Ann Arbor, MI 48109 (United States); Yang, Xuesong, E-mail: yang_xuesong@126.com [Key Laboratory for Regenerative Medicine of The Ministry of Education, Department of Histology and Embryology, School of Medicine, Jinan University, Guangzhou 510632 (China)

2013-05-01

Formation of the neural tube is the morphological hallmark for development of the embryonic central nervous system (CNS). Therefore, neural tube development is a crucial step in the neurulation process. Slit/Robo signaling was initially identified as a chemo-repellent that regulated axon growth cone elongation, but its role in controlling neural tube development is currently unknown. To address this issue, we investigated Slit/Robo1 signaling in the development of chick neCollege of Life Sciences Biocentre, University of Dundee, Dundee DD1 5EH, UKural tube and transgenic mice over-expressing Slit2. We disrupted Slit/Robo1 signaling by injecting R5 monoclonal antibodies into HH10 neural tubes to block the Robo1 receptor. This inhibited the normal development of the ventral body curvature and caused the spinal cord to curl up into a S-shape. Next, Slit/Robo1 signaling on one half-side of the chick embryo neural tube was disturbed by electroporation in ovo. We found that the morphology of the neural tube was dramatically abnormal after we interfered with Slit/Robo1 signaling. Furthermore, we established that silencing Robo1 inhibited cell proliferation while over-expressing Robo1 enhanced cell proliferation. We also investigated the effects of altering Slit/Robo1 expression on Sonic Hedgehog (Shh) and Pax7 expression in the developing neural tube. We demonstrated that over-expressing Robo1 down-regulated Shh expression in the ventral neural tube and resulted in the production of fewer HNK-1{sup +} migrating neural crest cells (NCCs). In addition, Robo1 over-expression enhanced Pax7 expression in the dorsal neural tube and increased the number of Slug{sup +} pre-migratory NCCs. Conversely, silencing Robo1 expression resulted in an enhanced Shh expression and more HNK-1{sup +} migrating NCCs but reduced Pax7 expression and fewer Slug{sup +} pre-migratory NCCs were observed. In conclusion, we propose that Slit/Robo1 signaling is involved in regulating neural tube

Pollen reference collection digitization

NARCIS (Netherlands)

Ercan, F.E.Z.; Donders, T.H.; Bijl, P.K.; Wagner, F.

2016-01-01

The extensive Utrecht University pollen reference collection holds thousands of pollen samples of many species and genera from all over the world and has been a basis for the widely-used North West European Pollen Flora. These samples are fixed on glass slides for microscopy use, but the aging

Sustained release of growth hormone and sodium nitrite from biomimetic collagen coating immobilized on silicone tubes improves endothelialization.

Science.gov (United States)

Salehi-Nik, Nasim; Malaie-Balasi, Zahra; Amoabediny, Ghassem; Banikarimi, Seyedeh Parnian; Zandieh-Doulabi, Behrouz; Klein-Nulend, Jenneke

2017-08-01

Biocompatibility of biomedical devices can be improved by endothelialization of blood-contacting parts mimicking the vascular endothelium's function. Improved endothelialization might be obtained by using biomimetic coatings that allow local sustained release of biologically active molecules, e.g. anti-thrombotic and growth-inducing agents, from nanoliposomes. We aimed to test whether incorporation of growth-inducing nanoliposomal growth hormone (nGH) and anti-thrombotic nanoliposomal sodium nitrite (nNitrite) into collagen coating of silicone tubes enhances endothelialization by stimulating endothelial cell proliferation and inhibiting platelet adhesion. Collagen coating stably immobilized on acrylic acid-grafted silicone tubes decreased the water contact angle from 102° to 56°. Incorporation of 50 or 500nmol/ml nNitrite and 100 or 1000ng/ml nGH into collagen coating decreased the water contact angle further to 48°. After 120h incubation, 58% nitrite and 22% GH of the initial amount of sodium nitrite and GH in nanoliposomes were gradually released from the nNitrite-nGH-collagen coating. Endothelial cell number was increased after surface coating of silicone tubes with collagen by 1.6-fold, and with nNitrite-nGH-collagen conjugate by 1.8-3.9-fold after 2days. After 6days, endothelial cell confluency in the absence of surface coating was 22%, with collagen coating 74%, and with nNitrite-nGH-collagen conjugate coating 83-119%. In the absence of endothelial cells, platelet adhesion was stimulated after collagen coating by 1.3-fold, but inhibited after nNitrite-nGH-collagen conjugate coating by 1.6-3.7-fold. The release of anti-thrombotic prostaglandin I 2 from endothelial cells was stimulated after nNitrite-nGH-collagen conjugate coating by 1.7-2.2-fold compared with collagen coating. Our data shows improved endothelialization and blood compatibility using nNitrite-nGH-collagen conjugate coating on silicone tubes suggesting that these coatings are highly suitable

[Sensitization to Castanea sativa pollen and pollinosis in northern Extremadura (Spain)].

Science.gov (United States)

Cosmes Martín, P M; Moreno Ancillo, A; Domínguez Noche, C; Gutiérrez Vivas, A; Belmonte Soler, J; Roure Nolla, J M

2005-01-01

Castanea sativa pollen allergy has generally been considered to be uncommon and clinically insignificant. In our geographical area (Plasencia, Cáceres, Spain) Castanea sativa pollen is a major pollen. To determine the atmospheric fluctuations and prevalence of patients sensitized to Castanea pollen in our region and to compare this sensitization with sensitizations to other pollens. Patients with respiratory symptoms attending our outpatient clinic for the first time in 2003 were studied. The patients underwent skin prick tests with commercial extracts of a battery of inhalants including Castanea sativa pollen. Serologic specific IgE to Castanea sativa pollen was determined using the CAP system (Pharmacia and Upjohn, Uppsala, Sweden). Airborne pollen counts in our city were obtained using Cour collection apparatus over a 4-year period (2000 to 2003). The most predominant pollens detected were (mean of the maximal weekly concentrations over 4 years in pollen grains/m3): Quercus 968, Poacea 660, Olea 325, Platanus 229, Pinus 126, Cupresaceae 117, Plantago 109, Alnus 41, Populus 40, Castanea 32. We studied 346 patients (mean age: 24.1 years). In 210 patients with a diagnosis of pollinosis, the percentages of sensitization were: Dactylis glomerata 80.4%, Olea europea 71.9%, Fraxinus excelsior 68%, Plantago lanceolata 62.8%, Chenopodium album 60.9%, Robinia pseudoacacia 49%, Artemisia vulgaris 43.8%, Platanus acerifolia 36.6%, Parietaria judaica 36.1%, Populus nigra 32.3%, Betula alba 27.6%, Quercus ilex 21.4%, Alnus glutinosa 20.9%, Cupressus arizonica 7.6% and Castanea sativa 7.1%. Fifteen patients were sensitized to Castanea sativa and 14 had seasonal rhinoconjunctivitis and asthma. Ten patients had serum specific IgE to Castanea pollen (maximum value: 17.4 Ku/l). Castanea pollen is present in our area in large amounts from the 23rd to the 28th weeks of the year, with a peak pollen count in the 25th week. The most important allergenic pollens in northern Extremadura

Relative growth in the fiddler crab Uca uruguayensis Nobili, 1901 (Brachyura, Ocypodidae from Garças River mangrove, Guaratuba Bay, southern Brazil

Directory of Open Access Journals (Sweden)

Salise Brandt Martins

Full Text Available A study on the relative growth was carried out in a population of the fiddler crab Uca uruguayensis from the mangrove of Garças River, Guaratuba Bay, Paraná State, southern Brazil. The dimensions analyzed were the length of the major chela (LMC of males and width of the abdomen (AW of females, because they are related to reproductive activities of waving (males and egg incubation (females. The cheliped handedness in males was also analyzed. The LMC was measured in 480 males, the AW in 566 females, and all crabs had the carapace width (CW measured that was considered as the reference dimension for both sexes. The inflection point in the graphs between each the dimensions and CW was calculated with the aid of the software REGRANS. The CW ranged from 2.33 to 8.33 mm in males and from 1.65 to 7.79 mm in females. The relationship between CW and LMC showed an inflection point at 4.14 mm CW among males, and between CW and AW at 3.52 mm CW among females. The allometric growth was positive for both dimensions throughout the entire ontogeny of both sexes, before and after the puberty. The equations describing the relationship between CW and LMC in males were: logLMC = - 0.695960 + 1.72.logCW for juveniles and logLMC = - 1.212513 + 2.5.logCW for adults. In females, the equations were logAW = - 0.519071 + 1.02.logCW and logAW = - 0.902874 + 1.73.logCW, respectively for juveniles and adults. The population of U. uruguayensis from Guaratuba Bay is composed of the smallest crabs, and it also attains morphological sexual maturity at smallest CW. The frequency of occurrence of right and left handed males was statistically the same (1:1 as in most population of fiddler crabs.

Influence of pollen nutrition on honey bee health: do pollen quality and diversity matter?

Science.gov (United States)

Di Pasquale, Garance; Salignon, Marion; Le Conte, Yves; Belzunces, Luc P; Decourtye, Axel; Kretzschmar, André; Suchail, Séverine; Brunet, Jean-Luc; Alaux, Cédric

2013-01-01

Honey bee colonies are highly dependent upon the availability of floral resources from which they get the nutrients (notably pollen) necessary to their development and survival. However, foraging areas are currently affected by the intensification of agriculture and landscape alteration. Bees are therefore confronted to disparities in time and space of floral resource abundance, type and diversity, which might provide inadequate nutrition and endanger colonies. The beneficial influence of pollen availability on bee health is well-established but whether quality and diversity of pollen diets can modify bee health remains largely unknown. We therefore tested the influence of pollen diet quality (different monofloral pollens) and diversity (polyfloral pollen diet) on the physiology of young nurse bees, which have a distinct nutritional physiology (e.g. hypopharyngeal gland development and vitellogenin level), and on the tolerance to the microsporidian parasite Nosemaceranae by measuring bee survival and the activity of different enzymes potentially involved in bee health and defense response (glutathione-S-transferase (detoxification), phenoloxidase (immunity) and alkaline phosphatase (metabolism)). We found that both nurse bee physiology and the tolerance to the parasite were affected by pollen quality. Pollen diet diversity had no effect on the nurse bee physiology and the survival of healthy bees. However, when parasitized, bees fed with the polyfloral blend lived longer than bees fed with monofloral pollens, excepted for the protein-richest monofloral pollen. Furthermore, the survival was positively correlated to alkaline phosphatase activity in healthy bees and to phenoloxydase activities in infected bees. Our results support the idea that both the quality and diversity (in a specific context) of pollen can shape bee physiology and might help to better understand the influence of agriculture and land-use intensification on bee nutrition and health.

Influence of pollen nutrition on honey bee health: do pollen quality and diversity matter?

Directory of Open Access Journals (Sweden)

Garance Di Pasquale

Full Text Available Honey bee colonies are highly dependent upon the availability of floral resources from which they get the nutrients (notably pollen necessary to their development and survival. However, foraging areas are currently affected by the intensification of agriculture and landscape alteration. Bees are therefore confronted to disparities in time and space of floral resource abundance, type and diversity, which might provide inadequate nutrition and endanger colonies. The beneficial influence of pollen availability on bee health is well-established but whether quality and diversity of pollen diets can modify bee health remains largely unknown. We therefore tested the influence of pollen diet quality (different monofloral pollens and diversity (polyfloral pollen diet on the physiology of young nurse bees, which have a distinct nutritional physiology (e.g. hypopharyngeal gland development and vitellogenin level, and on the tolerance to the microsporidian parasite Nosemaceranae by measuring bee survival and the activity of different enzymes potentially involved in bee health and defense response (glutathione-S-transferase (detoxification, phenoloxidase (immunity and alkaline phosphatase (metabolism. We found that both nurse bee physiology and the tolerance to the parasite were affected by pollen quality. Pollen diet diversity had no effect on the nurse bee physiology and the survival of healthy bees. However, when parasitized, bees fed with the polyfloral blend lived longer than bees fed with monofloral pollens, excepted for the protein-richest monofloral pollen. Furthermore, the survival was positively correlated to alkaline phosphatase activity in healthy bees and to phenoloxydase activities in infected bees. Our results support the idea that both the quality and diversity (in a specific context of pollen can shape bee physiology and might help to better understand the influence of agriculture and land-use intensification on bee nutrition and health.

The revised edition of korean calendar for allergenic pollens.

Science.gov (United States)

Oh, Jae-Won; Lee, Ha-Baik; Kang, Im-Joo; Kim, Seong-Won; Park, Kang-Seo; Kook, Myung-Hee; Kim, Bong-Seong; Baek, Hey-Sung; Kim, Joo-Hwa; Kim, Ja-Kyung; Lee, Dong-Jin; Kim, Kyu-Rang; Choi, Young-Jin

2012-01-01

The old calendar of pollens did not reflect current pollen distribution and concentrations that can be influenced by changes of weather and environment of each region in South Korea. A new pollen calendar of allergenic pollens was made based on the data on pollen concentrations obtained in eight regions nationwide between 1997 and 2009. The distribution of pollen was assessed every day at 8 areas (Seoul, Guri, Busan, Daegu, Jeonju, Kwangju, Kangneung, and Jeju) for 12 years between July 1, 1997 and June 30, 2009. Pollens were collected by using Burkard 7-day sampler (Burkard Manufacturing Co Ltd, UK). Pollens which were stained with Calberla's fuchsin staining solution were identified and counted. Pine became the highest pollen in May, and the pollen concentrations of oak and birch also became high. Ragweed appeared in the middle of August and showed the highest pollen concentration in the middles of September. Japanese hop showed a high concentration between the middle of August and the end of September, and mugwort appeared in the middles of August and its concentration increased up until early September. In Kangneung, birch appeared earlier, pine showed a higher pollen concentration than in the other areas. In Daegu, Oriental thuja and alder produced a large concentration of pollens. Pine produced a large concentration of pollens between the middle of April and the end of May. Weeds showed higher concentrations in September and mugwort appeared earlier than ragweed. In Busan the time of flowering is relatively early, and alder and Oriental thuja appeared earliest among all areas. In Kwangju, Oriental thuja and hazelnut appeared in early February. Japanese cedar showed the highest pollen concentration in March in Jeju. In conclusion, update information on pollen calendar in South Korea should be provided for allergic patients through the website to manage and prevent the pollinosis.

Cw rf operation of the FMIT RFQ

International Nuclear Information System (INIS)

Fazio, M.V.; Brandeberry, F.E.

1985-01-01

The 80-MHz RFQ for the Fusion Materials Irradiation Test Facility prototype accelerator has been rf conditioned for cw operation to the design field level of 17.5 MV/m (1.68 x Kilpatrick limit). Experimental results and operating experience will be discussed

Measurement of IgG antibodies to house dust mite and grass pollen by a solid-phase radioimmunoassay

Energy Technology Data Exchange (ETDEWEB)

Delespesse, G; Debisschop, M J; Flament, J [Hopital Saint Pierre, Louvain (Belgium). Lab. de Recherches de la Clinique Medicale

1979-09-01

A solid-phase radioimmunoassay was used to measure specific IgG antibodies to either Dermatophagoides pteronyssinus (DPT) or grass pollens. Radiolabelled protein A from Staphylococcus aureus (SpA) was used to determine the IgG antibodies attached to the microtubes. The binding of IgG from either normal or allergic sera to DPT-coated tubes was antigen specific and mediated by the Fab fragment of the immunoglobulin. IgG antibodies from non-allergic serum competed with IgE antibodies to DPT. IgE antibodies did not significantly interfere with the assay. Indeed heating a reaginic serum resulted in a striking reduction of the (/sup 125/I) anti- IgE binding to allergen-coated tubes without modifying the (/sup 125/I)-SpA binding. Furthermore, filtration of a reaginic serum through Sephacryl S-200 separated a peak of IgE antibodies. The solid phase method was more sensitive than a double-antibody technique employing the same DPT extract as labelled antigen. Non-allergic subjects had less IgG antibodies to DPT or grass pollens than allergic patients. In untreated patients, there was a good correlation between levels of IgG and IgE antibodies to grass pollens but not to DPT. Patients hyposensitized to house dust mite had on the average three times more specific IgG antibodies than untreated cases. (author).

Measurement of IgG antibodies to house dust mite and grass pollen by a solid-phase radioimmunoassay

International Nuclear Information System (INIS)

Delespesse, G.; Debisschop, M.J.; Flament, J.

1979-01-01

A solid-phase radioimmunoassay was used to measure specific IgG antibodies to either Dermatophagoides pteronyssinus (DPT) or grass pollens. Radiolabelled protein A from Staphylococcus aureus (SpA) was used to determine the IgG antibodies attached to the microtubes. The binding of IgG from either normal or allergic sera to DPT-coated tubes was antigen specific and mediated by the Fab fragment of the immunoglobulin. IgG antibodies from non-allergic serum competed with IgE antibodies to DPT. IgE antibodies did not significantly interfere with the assay. Indeed heating a reaginic serum resulted in a striking reduction of the ( 125 I) anti- IgE binding to allergen-coated tubes without modifying the ( 125 I)-SpA binding. Furthermore, filtration of a reaginic serum through Sephacryl S-200 separated a peak of IgE antibodies. The solid phase method was more sensitive than a double-antibody technique employing the same DPT extract as labelled antigen. Non-allergic subjects had less IgG antibodies to DPT or grass pollens than allergic patients. In untreated patients, there was a good correlation between levels of IgG and IgE antibodies to grass pollens but not to DPT. Patients hyposensitized to house dust mite had on the average three times more specific IgG antibodies than untreated cases. (author)

Development of a sealed-accelerator-tube neutron generator

Science.gov (United States)

Verbeke; Leung; Vujic

2000-10-01

Sealed-accelerator-tube neutron generators are being developed in Lawrence Berkeley National Laboratory (LBNL) for applications ranging from neutron radiography to boron neutron capture therapy and neutron activation analysis. The new generation of high-output neutron generators is based on the D-T fusion reaction, producing 14.1-MeV neutrons. The main components of the neutron tube--the ion source, the accelerator and the target--are all housed in a sealed metal container without external pumping. Thick-target neutron yield computations are performed in this paper to estimate the neutron yield of titanium and scandium targets. With an average deuteron beam current of 1 A and an energy of 120 keV, a time-averaged neutron production of approximately 10(14) n/s can be estimated for a tritiated target, for both pulsed and cw operations. In mixed deuteron/triton beam operation, a beam current of 2 A at 150 keV is required for the same neutron output. Recent experimental results on ion sources and accelerator columns are presented and discussed.

Storage of strawberry pollen

Directory of Open Access Journals (Sweden)

Rafet Aslantaş

2013-12-01

Full Text Available This study was carried out to determine storage ability of strawberry pollen at different temperatures for three different strawberry cultivars 'Aliso', 'Brio', and 'Cruz'. Strawberry pollen was stored at room temperature (22 ±2°C, +4°C, -4°C and -18°C in stabile humidity conditions. Strawberry poIlen was germinated using the hanging drop method in a 20% sucrose solution. Pollen germination rate increased because of low temperature storage. Pollen stored at room temperature and +4°C, -4°C, and -18°C was kept for 8 months, about one year, and 20 months, respectively. Pollen germination rates decreased as the length of storage period increased. The reaction of all cultivars tested on the duration and temperature of storage was similar.

Mycobiota and mycotoxins in bee pollen collected from different areas of Slovakia.

Science.gov (United States)

Kačániová, Miroslava; Juráček, Miroslav; Chlebo, Róbert; Kňazovická, Vladimíra; Kadasi-Horáková, Miriam; Kunová, Simona; Lejková, Jadža; Haščík, Peter; Mareček, Ján; Simko, Milan

2011-01-01

Contamination by microscopic fungi and mycotoxins in different bee pollen samples, which were stored under three different ways of storing as freezing, drying and UV radiation, was investigated. During spring 2009, 45 samples of bee-collected pollen were gathered from beekeepers who placed their bee colonies on monocultures of sunflower, rape and poppy fields within their flying distance. Bee pollen was collected from bees' legs by special devices placed at the entrance to hives. Samples were examined for the concentration and identification of microscopic fungi able to grow on Malt and Czapek-Dox agar and mycotoxins content [deoxynivalenol (DON), T-2 toxin (T-2), zearalenone (ZON) and total aflatoxins (AFL), fumonisins (FUM), ochratoxins (OTA)] by direct competitive enzyme-linked immunosorbent assays (ELISA). The total number of microscopic fungi in this study ranged from 2.98 ± 0.02 in frozen sunflower bee pollen to 4.06 ± 0.10 log cfu.g(-1) in sunflower bee pollen after UV radiation. In this study, 449 isolates belonging to 21 fungal species representing 9 genera were found in 45 samples of bee pollen. The total isolates were detected in frozen poppy pollen 29, rape pollen 40, sunflower pollen 80, in dried poppy pollen 12, rape pollen 36, sunflower 78, in poppy pollen after UV radiation treatment 54, rape 59 and sunflower 58. The most frequent isolates of microscopic fungi found in bee pollen samples of all prevalent species were Mucor mucedo (49 isolates), Alternaria alternata (40 isolates), Mucor hiemalis (40 isolates), Aspergillus fumigatus (33 isolates) and Cladosporium cladosporioides (31 isolates). The most frequently found isolates were detected in sunflower bee pollen frozen (80 isolates) and the lowest number of isolates was observed in poppy bee pollen dried (12 isolates). The most prevalent mycotoxin of poppy bee pollen was ZON (361.55 ± 0.26 μg.kg(-1)), in rape bee pollen T-2 toxin (265.40 ± 0.18 μg.kg(-1)) and in sunflower bee pollen T-2 toxin

Analysis of airborne pollen grains in Konya, Turkey, 2005

International Nuclear Information System (INIS)

Altunoglu, M.K.; Bicakci, A.; Temel, M.; Kargioglu, M.

2010-01-01

In this study, airborne pollen grains of Konya province were investigated using Durham sampler from January to December 2005. A total of 4420 pollen grains/cm/sup 2/ which belonged to 29 taxa and 9 unidentified pollen grains were recorded. From identified taxa, 19 belong to arboreal and 10 taxa to non-arboreal plants. Total pollen grains consist of 87,49% arboreal, 12,31% non-arboreal plants and 0,20% unidentified pollen grains. In the investigated region, from arboreal plant taxa Pinus spp. (21,63%), Fraxinus spp. (21,13%), Cupressaceae (15,84%), Ailanthus spp. (7,47%), Platanus spp. (3,80%), Acer spp. (3,28%), Populus spp. (1,86%), Sophora spp. (3,85%) and from non-arboreal plant taxa Chenopodiaceae / Amaranthaceae (4,77%), Poaceae (3,67%) were responsible for the greatest amount of pollen. During the study period, the pollen fall reached its highest level in March. (author)

A reliable cw Lyman-{alpha} laser source for future cooling of antihydrogen

Energy Technology Data Exchange (ETDEWEB)

Kolbe, Daniel, E-mail: kolbed@uni-mainz.de; Beczkowiak, Anna; Diehl, Thomas; Koglbauer, Andreas; Sattler, Matthias; Stappel, Matthias; Steinborn, Ruth; Walz, Jochen [Johannes Gutenberg-Universitaet, Institut fuer Physik (Germany)

2012-12-15

We demonstrate a reliable continuous-wave (cw) laser source at the 1 S-2 P transition in (anti)hydrogen at 121.56 nm (Lyman-{alpha}) based on four-wave sum-frequency mixing in mercury. A two-photon resonance in the four-wave mixing scheme is essential for a powerful cw Lyman-{alpha} source and is well investigated.

A reliable cw Lyman-α laser source for future cooling of antihydrogen

International Nuclear Information System (INIS)

Kolbe, Daniel; Beczkowiak, Anna; Diehl, Thomas; Koglbauer, Andreas; Sattler, Matthias; Stappel, Matthias; Steinborn, Ruth; Walz, Jochen

2012-01-01

We demonstrate a reliable continuous-wave (cw) laser source at the 1 S–2 P transition in (anti)hydrogen at 121.56 nm (Lyman-α) based on four-wave sum-frequency mixing in mercury. A two-photon resonance in the four-wave mixing scheme is essential for a powerful cw Lyman-α source and is well investigated.

Efficacy of recombinant birch pollen vaccine for the treatment of birch-allergic rhinoconjunctivitis

DEFF Research Database (Denmark)

Pauli, Gabrielle; Larsen, Tina H; Rak, Sabina