15 research outputs found

    Gene expression analysis in the roots of salt stressed wheat and the cytogenetic derivatives of wheat combined with the salt-tolerant wheatgrass, Lophopyrum elongatum

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    Lophopyrum elongatum is among one of the most salt tolerant members of the Triticeae; important genetic stocks developed from crosses between wheat and L. elongatum provide a unique opportunity to compare gene expression in response to salt stress between these highly related species. The octaploid amphiploid contains the entire genome of T. aestivum and L. elongatum, and the wheat disomic substitution line DS3E(3A) has chromosome 3A of wheat replaced by chromosome 3E of L. elongatum. In this study, microarray analysis was used to characterize gene expression profiles in the roots of three genotypes, Triticum aestivum, the octaploid amphiploid, and the DS3E(3A) substitution line, in response to salt stress. We first examined changes in gene expression in wheat over a time course of three days of salt stress, and then compared changes in gene expression in wheat, the T. aestivum x L. elongatum amphiploid and in the DS3E(3A) substitution line after three days of salt stress. In the time course experiment, 237 genes had a 1.5 fold or greater change at least once out of three time points assayed in the experiment. The comparison between the three genotypes revealed 304 genes with significant differences in changes of expression between the genotypes. Forty two of these genes had at least a two-fold change in expression in response to salt treatment; 18 of these genes have signaling or regulatory function. Genes with significant differences in induction or repression between genotypes included transcription factors, protein kinases, ubiquitin ligases and genes related to phospholipid signaling

    Characterization of the caleosin gene family in the Triticeae

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    Background The caleosin genes encode proteins with a single conserved EF hand calcium-binding domain and comprise small gene families found in a wide range of plant species. Some members of the gene family have been shown to be upregulated by environmental stresses including low water availability and high salinity. Caleosin 3 from wheat has been shown to interact with the α-subunit of the heterotrimeric G proteins, and to act as a GTPase activating protein (GAP). This study characterizes the size and diversity of the gene family in wheat and related species and characterizes the differential tissue-specific expression of members of the gene family. Results A total of 34 gene family members that belong to eleven paralogous groups of caleosins were identified in the hexaploid bread wheat, T. aestivum. Each group was represented by three homeologous copies of the gene located on corresponding homeologous chromosomes, except the caleosin 10, which has four gene copies. Ten gene family members were identified in diploid barley, Hordeum vulgare, and in rye, Secale cereale, seven in Brachypodium distachyon, and six in rice, Oryza sativa. The analysis of gene expression was assayed in triticale and rye by RNA-Seq analysis of 454 sequence sets and members of the gene family were found to have diverse patterns of gene expression in the different tissues that were sampled in rye and in triticale, the hybrid hexaploid species derived from wheat and rye. Expression of the gene family in wheat and barley was also previously determined by microarray analysis, and changes in expression during development and in response to environmental stresses are presented. Conclusions The caleosin gene family had a greater degree of expansion in the Triticeae than in the other monocot species, Brachypodium and rice. The prior implication of one member of the gene family in the stress response and heterotrimeric G protein signaling, points to the potential importance of the caleosin gene family. The complexity of the family and differential expression in various tissues and under conditions of abiotic stress suggests the possibility that caleosin family members may play diverse roles in signaling and development that warrants further investigation

    Mechanism of tumor cell invasion and metastasis based on loss of adhesion: the role of altered N-cadherin processing

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    Abstract Of all the processes that occur during tumor progression, invasion and the formation of secondary metastases are the most clinically relevant but the least well elucidated at the molecular level. Yet, it is now well established that alterations in classes of adhesion molecules correlate with malignant transformation. These alterations include reduction in surface adhesion molecules, as well as changes in the profile and function of adhesion molecules expressed at the cell surface. Classical cadherins are key cell adhesion molecules in epithelia that mediate Ca2+-dependent intercellular interactions. They are expressed as precursor proteins that undergo proteolytic processing of the prodomain to generate adhesively competent cadherins at the cell surface. Classical cadherins play central roles in tumor development. N-cadherin expression has been shown to correlate with increased tumor cell motility and metastasis. However, N-cadherin mediated adhesion is a robust phenomenon, and so would seem to be inconsistent with the “release” from intercellular adhesion required for invasion. Here we show that in the most migratory cells, altered post-translational processing by proprotein convertase enzymes results in non-adhesive forms of N-cadherin at the cell surface, although N-cadherin levels remain constant in representative gliomas and melanomas. Surprisingly, one of these forms is N-cadherin with the prodomain intact, and the other is cleaved at a novel second site, downstream of Trp2, which has been shown to be essential for cadherin-mediated adhesivity. Alternatively cleaved N-cadherin in high abundance (~ 70%) and mature N-cadherin co-exist on the cell surface, and we suggest that the ratio of the functionally antagonistic moieties directly correlates with invasion potential. Our work provides insight into what may be a widespread mechanism for tumor progression, invasion and metastasis, presents new avenues for diagnosis and treatment strategies, andRĂ©sumĂ© Parmi les phĂ©nomĂšnes associĂ©s Ă  la progression de la tumeur, l'invasion et la mĂ©tastase sont des Ă©tapes mĂ©dicalement importantes. Encore aujourd'hui, ces phĂ©nomĂšnes demeurent mystĂ©rieux. Par contre, il est trĂšs bien Ă©tabli que la modification des molĂ©cules d'adhĂ©sion accompagne la transformation maligne. Ce type de modification inclut la diminution, l'altĂ©ration du patron d'expression et la fonction des molĂ©cules d'adhĂ©sion Ă  la surface cellulaire. Les cadhĂ©rines classiques sont des molĂ©cules d'adhĂ©sion clef chez les cellules Ă©pithĂ©liales par leur implication dans les interactions intercellulaires en prĂ©sence d'ions de calcium. Ces cadhĂ©rines sont exprimĂ©es sous une forme prĂ©curseur et maturent par un processus protĂ©olytique impliquant la perte du peptide prĂ©curseur et l'acheminement de la protĂ©ine fonctionnelle Ă  la surface de la cellule. Les cadhĂ©rines classiques sont impliquĂ©es dans le dĂ©veloppement de diffĂ©rentes tumeurs. Il existe une corrĂ©lation entre l'expression de N-cadhĂ©rine et une augmentation de l'invasion et la mĂ©tastase des cellules cancĂ©reuses. Pourtant, l'adhĂ©sion de N-cadhĂ©rine est trĂšs robuste, une observation inconsistante avec l'abolition de l'adhĂ©sion intercellulaire requise durant l'invasion. Nous dĂ©montrons que chez les cellules les plus invasives, un processus protĂ©olytique modifiĂ© par les enzymes convertases rĂ©sulte Ă  des formes de N-cadhĂ©rines non adhĂ©sives Ă  la surface cellulaire, bien que le niveau total de N-cadhĂ©rine demeure inchangĂ© dans une population hĂ©tĂ©rogĂšne de gliomes et mĂ©lanomes. Il Ă©tait surprenant de constater qu'une de ces formes avait maintenu le peptide prĂ©curseur intact, tandis que l'autre forme a subi un clivage protĂ©olytique aprĂšs l'acide aminĂ© tryptophane, en position 2 de la protĂ©ine. Cet acide aminĂ© est nĂ©cessaire pour mĂ©dier l'adhĂ©sion des cadhĂ©rines. Nous dĂ©montrons que les formes matures (mineur) et aberrantes (majeure, ~70%) de N-ca

    Haemophilus somnus Possesses Two Systems for Acquisition of Transferrin-Bound Iron

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    Haemophilus somnus strain 649 was found to acquire iron from ovine, bovine, and goat transferrins (Tfs). Expression of Tf receptors, as evaluated by solid-phase binding assays, required the organisms to be grown under iron-restricted conditions in the presence of Tf. Competition binding assays revealed the presence of two distinct Tf-binding receptor systems, one specific for bovine Tf and the other capable of binding all three ruminant Tfs. Affinity isolation procedures using total membranes yielded three putative bovine Tf-binding polypeptides and one putative ovine and goat Tf-binding polypeptide. PCR amplification followed by DNA sequence analyses revealed that H. somnus strain 649 possesses genes that encode a bipartite TbpA-TbpB receptor along with a homolog of the Histophilus ovis single-component TbpA receptor. Expression of TbpB and the single-component TbpA would appear to be subject to a form of phase variation involving homopolymeric nucleotide tracts within the structural genes

    Opposite Roles of Furin and PC5A in N-Cadherin Processing

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    We recently demonstrated that lack of Furin-processing of the N-cadherin precursor (proNCAD) in highly invasive melanoma and brain tumor cells results in the cell-surface expression of a nonadhesive protein favoring cell migration and invasion in vitro. Quantitative polymerase chain reaction analysis of malignant human brain tumor cells revealed that of all proprotein convertases (PCs) only the levels of Furin and PC5A are modulated, being inversely (Furin) or directly (PC5A) correlated with brain tumor invasive capacity. Intriguingly, the N-terminal sequence following the Furin-activated NCAD site (RQKR↓DW161, mouse nomenclature) reveals a second putative PC-processing site (RIRSDR↓DK189) located in the first extracellular domain. Cleavage at this site would abolish the adhesive functions of NCAD because of the loss of the critical Trp161. This was confirmed upon analysis of the fate of the endogenous prosegment of proNCAD in human malignant glioma cells expressing high levels of Furin and low levels of PC5A (U343) or high levels of PC5A and negligible Furin levels (U251). Cellular analyses revealed that Furin is the best activating convertase releasing an ∌17-kDa prosegment, whereas PC5A is the major inactivating enzyme resulting in the secretion of an ∌20-kDa product. Like expression of proNCAD at the cell surface, cleavage of the NCAD molecule at RIRSDR↓DK189 renders the U251 cancer cells less adhesive to one another and more migratory. Our work modifies the present view on posttranslational processing and surface expression of classic cadherins and clarifies how NCAD possesses a range of adhesive potentials and plays a critical role in tumor progression

    Surface Expression of Precursor N-cadherin Promotes Tumor Cell Invasion12

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    The expression of N-cadherin (NCAD) has been shown to correlate with increased tumor cell motility and metastasis. However, NCAD-mediated adhesion is a robust phenomenon and therefore seems to be inconsistent with the “release” from intercellular adhesion required for invasion. We show that in the most invasive melanoma and brain tumor cells, altered posttranslational processing results in abundant nonadhesive precursor N-cadherin (proNCAD) at the cell surface, although total NCAD levels remain constant. We demonstrate that aberrantly processed proNCAD promotes cell migration and invasion in vitro. Furthermore, in human tumor specimens, we find high levels of proNCAD as well, supporting an overall conclusion that proNCAD and mature NCAD coexist on these tumor cell surfaces and that it is the ratio between these functionally antagonistic moieties that directly correlates with invasion potential. Our work provides insight into what may be a widespread mechanism for invasion and metastasis and challenges the current dogma of the functional roles played by classic cadherins in tumor progression

    Early fermentation volatile metabolite profile of non-Saccharomyces yeasts in red and white grape must: A targeted approach

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    Saccharomyces cerevisiae is the main driver of alcoholic fermentation. It is typically inoculated at high levels to ensure successful implantation as well as reduce the risks of stuck fermentations and off-flavor production. However, winemakers have found that wines produced with only S. cerevisiae can be lacking in complexity compared to fermentations where non-Saccharomyces yeasts are more active. This study sought to understand the early fermentation characteristics of Kazachstania gamospora, Lachancea thermotolerans, Metschnikowia pulcherrima, Torulaspora delbrueckii and Zygosaccharomyces kombuchaensis in both Sauvignon blanc and Syrah musts. S. cerevisiae was used as a control. Solid-phase microextraction coupled to GC–MS was used to evaluate the musts once they reached 2% ethanol concentration. The method targeted 90 different compounds known to occur in wine and/or be produced by yeast during fermentation. For the first time, K. gamospora and Z. kombuchaensis have been studied in the context of wine. While the other yeasts are commercially available starter cultures, they have never been profiled this extensively. Analysis showed that each yeast profile was unique and different based on the must. The non-Saccharomyces yeasts produced lower concentrations of esters, alcohols and terpenes with the exception of K. gamospora which produced more total esters than the control
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