The objective of this study was to identify barley leaf proteins differentially regulated in response to drought and heat and the combined stresses in context of the morphological and physiological changes that also occur. The Syrian landrace Arta and the Australian cultivar Keel were subjected to drought, high temperature, or a combination of both treatments starting at heading. Changes in the leaf proteome were identified using differential gel electrophoresis and mass spectrometry. The drought treatment caused strong reductions of biomass and yield, while photosynthetic performance and the proteome were not significantly changed. In contrast, the heat treatment and the combination of heat and drought reduced photosynthetic performance and caused changes of the leaf proteome. The proteomic analysis identified 99 protein spots differentially regulated in response to heat treatment, 14 of which were regulated in a genotype-specific manner. Differentially regulated proteins predominantly had functions in photosynthesis, but also in detoxification, energy metabolism, and protein biosynthesis. The analysis indicated that de novo protein biosynthesis, protein quality control mediated by chaperones and proteases, and the use of alternative energy resources, i.e. glycolysis, play important roles in adaptation to heat stress. In addition, genetic variation identified in the proteome, in plant growth and photosynthetic performance in response to drought and heat represent stress adaption mechanisms to be exploited in future crop breeding efforts.

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American Association of Cereal Chem- ists/AOAC collaborative study was conducted to evaluate the accuracy and reliability of an enzyme assay kit procedure for measurement of total starch in a range of cereal grains and products. The flour sample is incubated at 95°C with thermostable α-amylase to catalyze the hydrolysis of starch to maltodextrins, the pH of the slurry is adjusted, and the slurry is treated with a highly purified amyloglucosidase to quantitatively hydrolyze the dextrins to glucose. Glucose is measured with glucose oxidase-peroxidase reagent. Thirty-two collaborators were sent 16 homogeneous test samples as 8 blind duplicates. These samples included chicken feed pellets, white bread, green peas, high- amylose maize starch, white wheat flour, wheat starch, oat bran, and spaghetti. All samples were analyzed by the standard procedure as detailed above; 4 samples (high-amylose maize starch and wheat starch) were also analyzed by a method that requires the samples to be cooked first in dimethyl sulfoxide (DMSO). Relative standard deviations for repeatability (RSDr) ranged from 2.1 to 3.9%, and relative standard deviations for reproducibility (RSDr) ranged from 2.9 to 5.7%. The RSDr value for high amylose maize starch analyzed by the standard (non-DMSO) procedure was 5.7%; the value

Formation and structural transformation of inverse poly(styrene)-block-poly(2-vinylpyridine) micelles whose polyvinylpyridine core was loaded with HAuCl4 or with elementary gold nanoclusters was studied by combined static and dynamic light scattering. A transformation in the morphology from spherical particles (small R g/R h ratio) to large anisomeric objects (large R g/R h ratio) was observed by decreasing the concentration of the block copolymer below the critical micelle concentration. At this point, the polymer chains are molecularly dispersed and no longer able to prevent uncontrolled growth of the gold nanoclusters.

The male gametophyte (or pollen) plays an obligatory role during sexual reproduction of higher plants. The extremely reduced complexity of this organ renders pollen a valuable experimental system for studying fundamental aspects of plant biology such as cell fate determination, cell-cell interactions, cell polarity, and tip-growth. Here, we present the first reference map of the mature pollen proteome of the dicotyledonous model plant species, Arabidopsis thaliana. Based on two-dimensional gel electrophoresis, matrix-assisted laser desorption/ionization time-of-flight, and electrospray quadrupole time-of-flight mass spectrometry, we reproducibly identified 121 different proteins in 145 individual spots. The presence, subcellular localization, and functional classification of the identified proteins are discussed in relation to the pollen transcriptome and the full protein complement encoded by the nuclear Arabidopsis genome. Ó 2005 Elsevier Inc. All rights reserved.Keywords: Arabidopsis thaliana; Male gametophyte; Mass spectrometry; Mature pollen; Proteome; Two-dimensional gel electrophoresis In higher plants, development of the male gametophyte is a well-programmed and elaborate process. Male sporogenesis begins with the division of a diploid sporophytic cell giving rise to the anther wall of the stamen and the sporogenic cells. The latter cells then undergo several mitoses to differentiate into pollen mother cells. Subsequently, each diploid pollen mother cell forms a tetrad of haploid microspores via a round of DNA replication followed by two consecutive meiotic divisions. Each uninucleate microspore then undergoes an asymmetric mitotic division forming a large vegetative cell and a smaller generative cell (i.e., the bicellular pollen stage). In Arabidopsis, the generative cell undergoes another mitotic division giving rise to two sperm cells (i.e., the tricellular pollen stage). Following pollination, the vegetative cell controls the further development of the mature pollen grain and growth of the pollen tube into the style until both sperm cell nuclei are delivered to the embryo sac in the ovule, where they participate in double fertilization [1,2].The last two decades have been marked by increasing efforts to decipher the genetic and molecular basis of pollen development and functions [reviewed in 1,3,4]. In the model plant Arabidopsis thaliana, the extremely reduced, tricellular male gametophyte constitutes an ideal experimental system for analyses of important biological processes in higher plant reproduction. In addition, it represents a very useful model for studying fundamental aspects of plant biology such as cell fate determination, cell-cell interactions, cell polarity, and tip-growth [5][6][7].The availability of the full genome sequence of Arabidopsis [8] has made genome-wide, microarray-based analyses of the male gametophyte transcriptome of this model plant possible [9][10][11][12]. 13,977 male gametophyte-expressed mRNAs were recently identified using the ATH1 Genome Array, which cover...

ENOD40 is expressed at an early stage in root nodule organogenesis in legumes. Identification of ENOD40 homologs in nonleguminous plants suggests that this gene may have a more general biological function. In vitro translation of soybean ENOD40 mRNA in wheat germ extracts revealed that the conserved nucleotide sequence at the 5 end (region I) encodes two peptides of 12 and 24 aa residues (peptides A and B). These peptides are synthesized de novo from very short, overlapping ORFs. Appropriate ORFs are present in all legume ENOD40s studied thus far. In this case small peptides are directly translated from polycistronic eukaryotic mRNA. The 24-aa peptide B was detected in nodules by Western blotting. Both peptides specifically bind to the same 93-kDa protein, which was affinity purified from soybean nodules. Using peptide mass fingerprinting, we identified this binding protein as nodulin 100, which is a subunit of sucrose synthase. Based on our data we suggest that ENOD40 peptides are involved in the control of sucrose use in nitrogen-fixing nodules.translation ͉ short open reading frames ͉ peptide signals T he nodule on the roots of legumes is an organ induced by rhizobia in which they are hosted intracellularly and where they find an ideal environment for symbiotic nitrogen fixation. The plant genes that are specifically induced by nodulation factor-secreting rhizobia during early stages of nodule development have been termed early nodulin (ENOD) genes. Among these genes, ENOD40 is one of the earliest nodulins and appears to play an important role in root nodule organogenesis. ENOD40 is induced by nodulation factors and the phytohormone cytokinin, and its expression precedes the first cortical cell division (1, 2). In mature nodules, the expression of ENOD40 has been detected in cells surrounding vascular bundles (3, 4). In addition, this gene also is expressed at low levels in stem and root cells (3). Recent work (5) has revealed ENOD40 homologs also in the monocotyledonous plants rice and maize. ENOD40 is therefore widespread in the plant kingdom, suggesting that it may have a general biological function.A remarkable feature of legume ENOD40 genes is that they contain only short ORFs. Therefore, it was initially proposed that this gene functions as an RNA (6, 7). All ENOD40 genes studied thus far contain two highly conserved regions. Recently, it was reported that the 5Ј located conserved region I of soybean (Glycine max) ENOD40 encodes a small peptide (8). This work claimed that the peptide renders tobacco cells insensitive to high concentrations of auxin. However, these data were obtained by counting tobacco cells undergoing division and could not be reproduced by using other proliferation assays (9). Moreover, a study with transgenic clover containing an auxin-responsive promoter-␤-glucuronidase (GUS) fusion failed to show the involvement of this peptide in perturbing auxin balance (10). Although genetic approaches using translational fusions were used to study ENOD40 expression (11,12), no direct biochemica...

Phaeobacter inhibens DSM 17395, a member of the Roseobacter clade, was studied for its adaptive strategies to complex and excess nutrient supply, here mimicked by cultivation with Marine Broth (MB). During growth in process-controlled fermenters, P. inhibens DSM 17395 grew faster (3.6-fold higher μmax ) and reached higher optical densities (2.2-fold) with MB medium, as compared to the reference condition of glucose-containing mineral medium. Apparently, in the presence of MB medium, metabolism was tuned to maximize growth rate at the expense of efficiency. Comprehensive proteomic analysis of cells harvested at ½ ODmax identified 1783 (2D DIGE, membrane and extracellular protein-enriched fractions, shotgun) different proteins (50.5% coverage), 315 (based on 2D DIGE) of which displayed differential abundance profiles. Moreover, 145 different metabolites (intra- and extracellular combined) were identified, almost all of which (140) showed abundance changes. During growth with MB medium, P. inhibens DSM 17395 specifically formed the various proteins required for utilization of phospholipids and several amino acids, as well as for gluconeogenesis. Metabolic tuning on amino acid utilization is also reflected by massive discharge of urea to dispose the cell of excess ammonia. Apparently, P. inhibens DSM 17395 modulated its metabolism to simultaneously utilize diverse substrates from the complex nutrient supply.

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