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991.
Vivipary, the germination of seeds within the fruit prior to abscission from the maternal plant, is an important event in plants. Two main types of vivipary are known in vascular plants: true vivipary and pseudovivipary. In crop grasses, pseudovivipary is an undesirable character as it results in lower yields. To date, vivipary in the Cactaceae has been reported for less than 20 species, most of which are cultivated. Here, we report viviparous (cryptoviviparous-a subcategory of true vivipary) cacti in nature in members of the tribes Cacteae and Pachycereeae (subfamily Cactoideae). We present four species inhabiting coastal plains in areas subject to periodic flooding, namely, Ferocactus herrerae, Stenocereus alamosensis, S. thurberi, and Pachycereus schottii. These species from localities in northwestern Mexico had viviparous fruits and offspring in different stages of development. A potential trend in the data indicates that the overall proportion of viviparous plants is higher in coastal flooding areas relative to halophytic, nonflooding areas. In our view, vivipary is a reproductive strategy that has evolved to provide a more efficient mechanism favoring germination and new avenues for survival by contributing to population maintenance and short-distance dispersal on halophytic substrates. 相似文献
992.
Differential CO2 effect on primary carbon metabolism of flag leaves in durum wheat (Triticum durum Desf.)
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Iker Aranjuelo Gorka Erice Alvaro Sanz‐Sáez Cyril Abadie Françoise Gilard Erena Gil‐Quintana Jean‐Christophe Avice Christiana Staudinger Stefanie Wienkoop Jose L. Araus Jacques Bourguignon Juan J. Irigoyen Guillaume Tcherkez 《Plant, cell & environment》2015,38(12):2780-2794
C sink/source balance and N assimilation have been identified as target processes conditioning crop responsiveness to elevated CO2. However, little is known about phenology‐driven modifications of C and N primary metabolism at elevated CO2 in cereals such as wheat. Here, we examined the differential effect of elevated CO2 at two development stages (onset of flowering, onset of grain filling) in durum wheat (Triticum durum, var. Sula) using physiological measurements (photosynthesis, isotopes), metabolomics, proteomics and 15N labelling. Our results show that growth at elevated CO2 was accompanied by photosynthetic acclimation through a lower internal (mesophyll) conductance but no significant effect on Rubisco content, maximal carboxylation or electron transfer. Growth at elevated CO2 altered photosynthate export and tended to accelerate leaf N remobilization, which was visible for several proteins and amino acids, as well as lysine degradation metabolism. However, grain biomass produced at elevated CO2 was larger and less N rich, suggesting that nitrogen use efficiency rather than photosynthesis is an important target for improvement, even in good CO2‐responsive cultivars. 相似文献
993.
Diego Rojas-Benitez Patrick C. Thiaville Valérie de Crécy-Lagard Alvaro Glavic 《The Journal of biological chemistry》2015,290(30):18699-18707
N6-Threonylcarbamoyl-adenosine (t6A) is a universal modification occurring at position 37 in nearly all tRNAs that decode A-starting codons, including the eukaryotic initiator tRNA (tRNAiMet). Yeast lacking central components of the t6A synthesis machinery, such as Tcs3p (Kae1p) or Tcs5p (Bud32p), show slow-growth phenotypes. In the present work, we show that loss of the Drosophila tcs3 homolog also leads to a severe reduction in size and demonstrate, for the first time in a non-microbe, that Tcs3 is required for t6A synthesis. In Drosophila and in mammals, tRNAiMet is a limiting factor for cell and animal growth. We report that the t6A-modified form of tRNAiMet is the actual limiting factor. We show that changing the proportion of t6A-modified tRNAiMet, by expression of an un-modifiable tRNAiMet or changing the levels of Tcs3, regulate target of rapamycin (TOR) kinase activity and influences cell and animal growth in vivo. These findings reveal an unprecedented relationship between the translation machinery and TOR, where translation efficiency, limited by the availability of t6A-modified tRNA, determines growth potential in eukaryotic cells. 相似文献
994.
995.
Grossi-de-Sa MF Quezado de Magalhaes M Silva MS Silva SM Dias SC Nakasu EY Brunetta PS Oliveira GR Neto OB Sampaio de Oliveira R Soares LH Ayub MA Siqueira HA Figueira EL 《Journal of biochemistry and molecular biology》2007,40(5):773-782
Different isolates of the soil bacterium Bacillus thuringiensis produce multiple crystal (Cry) proteins toxic to a variety of insects, nematodes and protozoans. These insecticidal Cry toxins are known to be active against specific insect orders, being harmless to mammals, birds, amphibians, and reptiles. Due to these characteristics, genes encoding several Cry toxins have been engineered in order to be expressed by a variety of crop plants to control insectpests. The cotton boll weevil, Anthonomus grandis, and the fall armyworm, Spodoptera frugiperda, are the major economically devastating pests of cotton crop in Brazil, causing severe losses, mainly due to their endophytic habit, which results in damages to the cotton boll and floral bud structures. A cry1Ia-type gene, designated cry1Ia12, was isolated and cloned from the Bt S811 strain. Nucleotide sequencing of the cry1Ia12 gene revealed an open reading frame of 2160 bp, encoding a protein of 719 amino acid residues in length, with a predicted molecular mass of 81 kDa. The amino acid sequence of Cry1Ia12 is 99% identical to the known Cry1Ia proteins and differs from them only in one or two amino acid residues positioned along the three domains involved in the insecticidal activity of the toxin. The recombinant Cry1Ia12 protein, corresponding to the cry1Ia12 gene expressed in Escherichia coli cells, showed moderate toxicity towards first instar larvae of both cotton boll weevil and fall armyworm. The highest concentration of the recombinant Cry1Ia12 tested to achieve the maximum toxicities against cotton boll weevil larvae and fall armyworm larvae were 230 microg/mL and 5 microg/mL, respectively. The herein demonstrated insecticidal activity of the recombinant Cry1Ia12 toxin against cotton boll weevil and fall armyworm larvae opens promising perspectives for the genetic engineering of cotton crop resistant to both these devastating pests in Brazil. 相似文献
996.
Mata A Boehm C Fleischman AJ Muschler GF Roy S 《International journal of nanomedicine》2007,2(3):389-406
Growth characteristics of human connective tissue progenitor (CTP) cells were investigated on smooth and textured substrates, which were produced using MEMS (microelectromechanical systems) fabrication technology. Human bone marrow derived cells were cultured for 9 days under conditions promoting osteoblastic differentiation on polydimethylsiloxane (PDMS) substrates comprising smooth (non-patterned) surfaces (SMOOTH), 4 different cylindrical post micro-textures (POSTS) that were 7-10 microm high and 5, 10, 20, and 40 microm diameter, respectively, and channel micro-textures (CHANNELS) with curved cross-sections that were 11 microm high, 45 microm wide, and separated by 5 microm wide ridges. Standard glass-tissue culture surfaces were used as controls. Micro-textures resulted in the modification of CTP morphology, attachment, migration, and proliferation characteristics. Specifically, cells on POSTS exhibited more contoured morphology with closely packed cytoskeletal actin microfilaments compared to the more random orientation in cells grown on SMOOTH. CTP colonies on 10 gm-diameter POSTS exhibited higher cell number than any other POSTS, and a significant increase in cell number (442%) compared to colonies on SMOOTH (71%). On CHANNELS, colonies tended to be denser (229%) than on POSTS (up to 140% on 10 microm POSTS), and significantly more so compared to those on SMOOTH (104%). 相似文献
997.
998.
Viviana Urtuvia Nataly Maturana Fernando Acevedo Carlos Peña Alvaro Díaz-Barrera 《World journal of microbiology & biotechnology》2017,33(11):198
Alginate is a linear polysaccharide that can be used for different applications in the food and pharmaceutical industries. These polysaccharides have a chemical structure composed of subunits of (1–4)-β-d-mannuronic acid (M) and its C-5 epimer α-l-guluronic acid (G). The monomer composition and molecular weight of alginates are known to have effects on their properties. Currently, these polysaccharides are commercially extracted from seaweed but can also be produced by Azotobacter vinelandii and Pseudomonas spp. as an extracellular polymer. One strategy to produce alginates with different molecular weights and with reproducible physicochemical characteristics is through the manipulation of the culture conditions during fermentation. This mini-review provides a comparative analysis of the metabolic pathways and molecular mechanisms involved in alginate polymerization from A. vinelandii and Pseudomonas spp. Different fermentation strategies used to produce alginates at a bioreactor laboratory scale are described. 相似文献
999.
Alvaro Duque Helene C. Muller-Landau Renato Valencia Dairon Cardenas Stuart Davies Alexandre de Oliveira Álvaro J. Pérez Hugo Romero-Saltos Alberto Vicentini 《Biodiversity and Conservation》2017,26(3):669-686
We analyze forest structure, diversity, and dominance in three large-scale Amazonian forest dynamics plots located in Northwestern (Yasuni and Amacayacu) and central (Manaus) Amazonia, to evaluate their consistency with prevailing wisdom regarding geographic variation and the shape of species abundance distributions, and to assess the robustness of among-site patterns to plot area, minimum tree size, and treatment of morphospecies. We utilized data for 441,088 trees (DBH ≥1 cm) in three 25-ha forest dynamics plots. Manaus had significantly higher biomass and mean wood density than Yasuni and Amacayacu. At the 1-ha scale, species richness averaged 649 for trees ≥1 cm DBH, and was lower in Amacayacu than in Manaus or Yasuni; however, at the 25-ha scale the rankings shifted, with Yasuni < Amacayacu < Manaus. Within each site, Fisher’s alpha initially increased with plot area to 1–10 ha, and then showed divergent patterns at larger areas depending on the site and minimum size. Abundance distributions were better fit by lognormal than by logseries distributions. Results were robust to the treatment of morphospecies. Overall, regional patterns in Amazonian tree species diversity vary with the spatial scale of analysis and the minimum tree size. The minimum area to capture local diversity is 2 ha for trees ≥1 cm DBH, or 10 ha for trees ≥10 cm DBH. The underlying species abundance distribution for Amazonian tree communities is lognormal, consistent with the idea that the rarest species have not yet been sampled. Enhanced sampling intensity is needed to fill the still large voids we have in plant diversity in Amazon forests. 相似文献
1000.
Assessing the assessments: evaluation of four impact assessment protocols for invasive alien species
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Anne Turbé Diederik Strubbe Emiliano Mori Martina Carrete François Chiron Philippe Clergeau Pablo González‐Moreno Marine Le Louarn Alvaro Luna Mattia Menchetti Wolfgang Nentwig Liviu G. Pârâu Jose‐Luis Postigo Wolfgang Rabitsch Juan Carlos Senar Simon Tollington Sonia Vanderhoeven Anne Weiserbs Assaf Shwartz 《Diversity & distributions》2017,23(3):297-307