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471.
Tomaz Rijavec ;Maja Kovac ;Ales Kladnik ;Prem S.Chourey ;Marina Dermastia 《Acta Botanica Sinica》2009,(9):840-849
We report here on a comparative developmental profile of plant hormone cytokinins in relation to cell size, cell number and endoreduplicaUon in developing maize caryopsis of a cell wall invertase-deficient miniature1 (mn1) seed mutant and its wild type, Mn1, genotype. Both genotypes showed extremely high levels of total cytokinins during the very early stages of development, followed by a marked and genotype specific reduction. While the decrease of cytokinins in Mn1 was associated with their deactivation by 9-glucosylation, the absolute and the relative part of active cytokinin forms was higher in the mutant. During the exponential growth phase of endosperm between 6 d after pollination and 9 d after pollination, the mean cell doubling time, the absolute growth rate and the level of endoreduplication were similar in the two genotypes. However, the entire duration of growth was longer in Mnl compared with mnl, resulting in a significantly higher cell number in the Mnl endosperm. These data correlate with the previously reported peak levels of the Mn1-encoded cell wall invertase-2 (INCW2) at 12 d after pollination in the Mn1 endosperm. A model showing possible crosstalk among cytokinins, cell cycle and cell wall invertase as causal to increased cell number and sink strength of the Mn1 developing endosperm is discussed. 相似文献
472.
María Escalante‐Pérez Ales Svatos Jorge Molina‐Torres Alexander Muck Enrique Ramirez‐Chávez Rosa‐María Ádame‐Alvarez Martin Heil 《The Plant journal : for cell and molecular biology》2013,73(4):546-554
Despite the ecological and evolutionary importance of nectar, mechanisms controlling its synthesis and secretion remain largely unknown. It is widely believed that nectar is ‘secreted phloem sap’, but current research reveals a biochemical complexity that is unlikely to stem directly from the phloem. We used the short daily peak in production of extrafloral nectar by Acacia cornigera to investigate metabolic and proteomic dynamics before, during and after 2 h of diurnal secretion. Neither hexoses nor dominating nectar proteins (nectarins) were detected in the phloem before or during nectar secretion, excluding the phloem as the direct source of major nectar components. Enzymes involved in the anabolism of sugars, amino acids, proteins, and nectarins, such as invertase, β–1,3–glucanase and thaumatin‐like protein, accumulated in the nectary directly before secretion and diminished quantitatively after the daily secretion process. The corresponding genes were expressed almost exclusively in nectaries. By contrast, protein catabolic enzymes were mainly present and active after the secretion peak, and may function in termination of the secretion process. Thus the metabolic machinery for extrafloral nectar production is synthesized and active during secretion and degraded thereafter. Knowing the key enzymes involved and the spatio‐temporal patterns in their expression will allow elucidation of mechanisms by which plants control nectar quality and quantity. 相似文献
473.
Roopa Thapar Jing L Wang Michal Hammel Ruiqiong Ye Ke Liang Chengcao Sun Ales Hnizda Shikang Liang Su S Maw Linda Lee Heather Villarreal Isaac Forrester Shujuan Fang Miaw-Sheue Tsai Tom L Blundell Anthony J Davis Chunru Lin Susan P Lees-Miller Terence R Strick John A Tainer 《Nucleic acids research》2021,49(2):1199
474.
Adam Miszta Radek Machán Ales Benda Andre J Ouellette Wim Th Hermens Martin Hof 《Journal of peptide science》2008,14(4):503-509
The present study has two main objectives. The first is to characterize antimicrobial peptide (AMP) cryptdin-4 (Crp-4) interactions with biological membranes and to compare those interactions with those of magainin 2. The second is to combine the complementary experimental approaches of laser scanning microscopy (LSM), ellipsometry, and Z-scan fluorescence correlation spectroscopy (FCS) to acquire comprehensive information on mechanisms of AMP interactions with supported phospholipid bilayers (SPBs)-a popular model of biological membranes. LSM shows appearance of inhomogeneities in spatial distribution of lipids in the bilayer after treatment with Crp-4. Ellipsometric measurements show that binding of Crp-4 does not significantly change the lipid structure of the bilayer (increase in adsorbed mass without a change in thickness of adsorbed layer). Furthermore, Crp-4 slows the lateral diffusion of lipids within the membrane as shown by Z-scan FCS. All changes of the bilayer induced by Crp-4 can be partially reversed by flushing the sample with excess of buffer. Bilayer interactions of magainin 2 are significantly different, causing large loss of lipids and extensive damage to the bilayer. It seems likely that differences in peptide mode of action, readily distinguished using these combined experimental methods, are related to the distinctive beta-sheet and alpha-helical structures of the respective peptides. 相似文献
475.
Jocelyne Favet Ales Lapanje Adriana Giongo Suzanne Kennedy Yin-Yin Aung Arlette Cattaneo Austin G Davis-Richardson Christopher T Brown Renate Kort Hans-Jürgen Brumsack Bernhard Schnetger Adrian Chappell Jaap Kroijenga Andreas Beck Karin Schwibbert Ahmed H Mohamed Timothy Kirchner Patricia Dorr de Quadros Eric W Triplett William J Broughton Anna A Gorbushina 《The ISME journal》2013,7(4):850-867
Ancient mariners knew that dust whipped up from deserts by strong winds travelled long distances, including over oceans. Satellite remote sensing revealed major dust sources across the Sahara. Indeed, the Bodélé Depression in the Republic of Chad has been called the dustiest place on earth. We analysed desert sand from various locations in Chad and dust that had blown to the Cape Verde Islands. High throughput sequencing techniques combined with classical microbiological methods showed that the samples contained a large variety of microbes well adapted to the harsh desert conditions. The most abundant bacterial groupings in four different phyla included: (a) Firmicutes—Bacillaceae, (b) Actinobacteria—Geodermatophilaceae, Nocardiodaceae and Solirubrobacteraceae, (c) Proteobacteria—Oxalobacteraceae, Rhizobiales and Sphingomonadaceae, and (d) Bacteroidetes—Cytophagaceae. Ascomycota was the overwhelmingly dominant fungal group followed by Basidiomycota and traces of Chytridiomycota, Microsporidia and Glomeromycota. Two freshwater algae (Trebouxiophyceae) were isolated. Most predominant taxa are widely distributed land inhabitants that are common in soil and on the surfaces of plants. Examples include Bradyrhizobium spp. that nodulate and fix nitrogen in Acacia species, the predominant trees of the Sahara as well as Herbaspirillum (Oxalobacteraceae), a group of chemoorganotrophic free-living soil inhabitants that fix nitrogen in association with Gramineae roots. Few pathogenic strains were found, suggesting that African dust is not a large threat to public health. 相似文献
476.
477.
A droplet fractionation method was previously developed to concentrate a dilute nonfoaming protein solution. In that earlier
study with invertase, it was demonstrated that droplets created by ultrasonic energy waves could be enriched up to 8 times
that of the initial dilute invertase solution. In this study, a mixture of bromelain (a foaming protein) and invertase (a
nonfoaming protein) is investigated as a preliminary step to determine if droplet fractionation can also be used to separate
a non-foaming protein from foaming proteins. The foaming mixture containing bromelain is first removed by bubbling the binary
mixture with air. After the foam is removed, the protein rich air-water interfacial layer is skimmed off (prior to droplet
fractionation) so as not to interfere with the subsequent droplet production from the remaining bulk liquid, rich in non-foaming
protein. Finally, sonic energy waves are then applied to this residual bulk liquid to recover droplets containing the non-foaming
protein, presumed to be invertase. The primary control variable used in this droplet fractionation process is the pH, which
ranged for separate experiments between 2 and 9. It was observed that the maximum overall protein partition coefficients of
5 and 4 were achieved at pH 2 and 4, respectively, for the initial foaming experiment followed by the post foaming droplet
fractionation experiment. 相似文献