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At least 865 records · Page 48Linked to original sources
PubMed2006

Analysis of fat body transcriptome from the adult tsetse fly, Glossina morsitans morsitans.

Tsetse flies (Diptera: Glossinidia) are vectors of pathogenic African trypanosomes. To develop a foundation for tsetse physiology, a normalized expressed sequence tag (EST) library was constructed from fat body tissue of immune-stimulated Glossina morsitans morsitans. Analysis of 20,257 high-quality ESTs yielded 6372 unique genes comprised of 3059 tentative consensus (TC) sequences and 3313 singletons (available at http://aksoylab.yale.edu). We analysed the putative fat body transcriptome based on homology to other gene products with known functions available in the public domain. In particular, we describe the immune-related products, reproductive function related yolk proteins and milk-gland protein, iron metabolism regulating ferritins and transferrin, and tsetse's major energy source proline biosynthesis. Expression analysis of the three yolk proteins indicates that all are detected in females, while only the yolk protein with similarity to lipases, is expressed in males. Milk gland protein, apparently important for larval nutrition, however, is primarily synthesized by accessory milk gland tissue.

Adipose Tissue↗
PubMed2005

Development of anonymous cDNA microarrays to study changes to the Senecio floral transcriptome during hybrid speciation.

Interspecific hybridization is an important process through which abrupt speciation can occur. In recent years, genetic changes associated with hybrid speciation have been identified through a variety of techniques, including AFLP/SSR mapping, GISH/FISH and cDNA-AFLP differential display. However, progress in using microarray technology to analyse whole genome/transcriptome changes associated with hybrid speciation has been limited due to the lack of extensive sequence data for many hybrid species and the difficulties in extrapolating results from commercially available microarrays for model species onto nonmodel hybrid taxa. Increasingly therefore researchers studying nonmodel systems are turning to the development of 'anonymous' cDNA microarrays, where the time and cost of producing microarrays is reduced by printing unsequenced cDNA clones, and sequencing only those clones that display interesting expression patterns. Here we describe the creation, testing and preliminary use of anonymous cDNA microarrays to study changes in floral transcriptome associated with allopolyploid speciation in the genus Senecio. We report a comparison of gene expression between the allohexaploid hybrid, Senecio cambrensis, its parental taxa Senecio squalidus (diploid) and Senecio vulgaris (tetraploid), and the intermediate triploid (sterile) hybrid Senecioxbaxteri. Anonymous microarray analysis revealed dramatic differences in floral gene expression between these four taxa and demonstrates the power of this technique for studies of the genetic impact of hybridization in nonmodel flowering plants.

Base Sequence↗
PubMed2006

Hfq-dependent alterations of the transcriptome profile and effects on quorum sensing in Pseudomonas aeruginosa.

The Pseudomonas aeruginosa quorum-sensing (QS) systems, Las and Rhl, control the production of several virulence factors and other proteins, which are important to sustain adverse conditions. A comparative transcriptome analysis of a rpoS (-) and a rpoS(-)hfq( -) strain indicated that the Sm-like RNA-binding protein Hfq affects approximately 5% of the P. aeruginosa O1 transcripts. Among these transcripts 72 were identified to be QS regulated. Expression studies revealed that Hfq does not control the master regulators of the Las system, LasR and LasI. Upon entry into stationary phase, Hfq exerted a moderate stimulatory effect on translation of the rhlR gene and on the qscR gene, encoding a LasR/RhlR homologue. However, Hfq considerably stimulated translation of the rhlI gene, encoding the synthetase of the autoinducer N-Butyryl-homoserine lactone (C4-HSL). Correspondingly, the C4-HSL levels were reduced in a hfq(-) strain. To elucidate the stimulatory effect of Hfq on rhlI expression we asked whether Hfq affects the stability of the regulatory RNAs RsmY and RsmZ, which have been implicated in sequestration of the translational repressor RsmA, which in turn is known to negatively regulate RhlI synthesis. We demonstrate that Hfq binds to and stabilizes the regulatory RNA RsmY, which is further shown to bind to the regulatory protein RsmA. A model for the Hfq regulatory network is presented, wherein an alleviation of the negative effect of RsmA accounts for the observed stimulation of rhlI expression by Hfq. The model is corroborated by the observation that a rsmY(-) mutant mimics the hfq(-) phenotype with regard to rhlI expression.

Bacterial Proteins↗
PubMed2006

Defining the Mga regulon: Comparative transcriptome analysis reveals both direct and indirect regulation by Mga in the group A streptococcus.

The regulator Mga in the group A streptococcus (GAS) is known to directly activate several virulence genes important for colonization and immune evasion. Transcriptome analysis comparing two mga-1 serotypes (M1 SF370, M6 JRS4) and one mga-2 serotype (M4 GA40634) against their isogenic mga-inactivated strains uncovered a broader Mga regulon profile containing both activated and repressed genes with predicted functions primarily related to sugar metabolism. This was reflected in the altered abilities of M1 and M4 Mga mutants to grow in chemically defined media with a single sugar source compared with their wild-type counterparts. Although the M1 and M4 Mga profiles were similar, the M6 JRS4 was clearly distinct, even from other M6 strains. Real-time RT-PCR and Northern blots confirmed that established core Mga regulon genes directly activated by Mga (emm, scpA, sof, fba) exhibited the highest activation levels across all strains tested. Spy2036 encoding a cytosolic hypothetical protein was highly activated in all three serotypes and was called gene regulated by Mga (grm). Mga bound directly to Pgrm, which overlaps the Mga-regulated Psof in OF+ strains, suggesting that grm is part of the core Mga regulon and Mga is able to activate divergently transcribed genes from a single site. Furthermore, Mga activated speB when detectable in the wild-type strain, although direct binding of Mga to PspeB could not be demonstrated. Thus, Mga is able to both directly and indirectly regulate genes shown to be important for virulence and the metabolic homeostasis of GAS.

Bacterial Proteins↗
PubMed2006

Conifer defence against insects: microarray gene expression profiling of Sitka spruce (Picea sitchensis) induced by mechanical wounding or feeding by spruce budworms (Choristoneura occidentalis) or white pine weevils (Pissodes strobi) reveals large-scale changes of the host transcriptome.

Conifers are resistant to attack from a large number of potential herbivores or pathogens. Previous molecular and biochemical characterization of selected conifer defence systems support a model of multigenic, constitutive and induced defences that act on invading insects via physical, chemical, biochemical or ecological (multitrophic) mechanisms. However, the genomic foundation of the complex defence and resistance mechanisms of conifers is largely unknown. As part of a genomics strategy to characterize inducible defences and possible resistance mechanisms of conifers against insect herbivory, we developed a cDNA microarray building upon a new spruce (Picea spp.) expressed sequence tag resource. This first-generation spruce cDNA microarray contains 9720 cDNA elements representing c. 5500 unique genes. We used this array to monitor gene expression in Sitka spruce (Picea sitchensis) bark in response to herbivory by white pine weevils (Pissodes strobi, Curculionidae) or wounding, and in young shoot tips in response to western spruce budworm (Choristoneura occidentalis, Lepidopterae) feeding. Weevils are stem-boring insects that feed on phloem, while budworms are foliage feeding larvae that consume needles and young shoot tips. Both insect species and wounding treatment caused substantial changes of the host plant transcriptome detected in each case by differential gene expression of several thousand array elements at 1 or 2 d after the onset of treatment. Overall, there was considerable overlap among differentially expressed gene sets from these three stress treatments. Functional classification of the induced transcripts revealed genes with roles in general plant defence, octadecanoid and ethylene signalling, transport, secondary metabolism, and transcriptional regulation. Several genes involved in primary metabolic processes such as photosynthesis were down-regulated upon insect feeding or wounding, fitting with the concept of dynamic resource allocation in plant defence. Refined expression analysis using gene-specific primers and real-time PCR for selected transcripts was in agreement with microarray results for most genes tested. This study provides the first large-scale survey of insect-induced defence transcripts in a gymnosperm and provides a platform for functional investigation of plant-insect interactions in spruce. Induction of spruce genes of octadecanoid and ethylene signalling, terpenoid biosynthesis, and phenolic secondary metabolism are discussed in more detail.

Animals↗
PubMed2004

Cambial meristem dormancy in trees involves extensive remodelling of the transcriptome.

The establishment of the dormant state in meristems involves considerable physiological and metabolic alterations necessary for surviving unfavourable growth conditions. However, a global molecular analysis of dormancy in meristems has been hampered by the difficulty in isolating meristem cells. We used cryosectioning to isolate purified cambial meristem cells from the woody plant Populus tremula during active growth and dormancy. These samples were used to generate meristem-specific cDNA libraries and for cDNA microarray experiments to define the global transcriptional changes underlying cambial dormancy. The results indicate a significant reduction in the complexity of the cambial transcriptome in the dormant state. Although cell division is terminated in the dormant cambium, the cell cycle machinery appears to be maintained in a skeletal state as suggested by the continued presence of transcripts for several cell cycle regulators. The downregulation of PttPIN1 and PttPIN2 transcripts explains the reduced basipetal polar auxin transport during dormancy. The induction of a member of the SINA family of ubiquitin ligases implicated in auxin signalling indicates a potential mechanism for modulation of auxin sensitivity during cambial dormancy. The metabolic alterations during dormancy are mirrored in the induction of genes involved in starch breakdown and the glyoxysomal cycle. Interestingly, the induction of RGA1 like gene suggests modification of gibberellin signalling in cambial dormancy. The induction of genes such as poplar orthologues of FIE and HAP2 indicates a potential role for these global regulators of transcription in orchestrating extensive changes in gene expression during dormancy.

Cell Cycle↗
PubMed2005

The stability of the Arabidopsis transcriptome in transgenic plants expressing the marker genes nptII and uidA.

The ATH1 Arabidopsis GeneChip from Affymetrix was used to search for transcriptome changes in Arabidopsis associated with the strong expression of transgenes regulated by constitutive promoters. The insertion and expression of the commonly used marker genes, uidA and nptII, did not induce changes to the expression patterns of the approximately 24 000 genes that were screened under optimal growth conditions and under physiological stress imposed by low temperatures. Approximately 8000 genes (35% of the Arabidopsis genome) underwent changes in gene expression in both wild-type and transgenic plants under abiotic stresses such as salt, dehydration, cold, and heat. This study provides detailed information on the extent of non-targeted or pleiotropic effects of transgenes on plants and shows that the transgenic and non-transgenic plants were equivalent in their global patterns of transcription. This information may help to extend our understanding and interpretation of the principle of substantial equivalence which is used as a first step in the biosafety evaluation of transgenic crops.

Arabidopsis↗
PubMed2006

Microarray analysis of the transcriptome as a stepping stone towards understanding biological systems: practical considerations and perspectives.

DNA microarrays have been used to characterize plant transcriptomes to answer various biological questions. While many studies have provided significant insights, there has been great debate about the general reliability of the technology and data analysis. When compared to well-established transcript analysis technologies, such as RNA blot analysis or quantitative reverse transcription-PCR, discrepancies have frequently been observed. The reasons for these discrepancies often relate to the technical and experimental systems. This review-tutorial addresses common problems in microarray analysis and describes: (i) methods to maximize extraction of valuable biological information from the vast amount of microarray data and (ii) approaches to balance resource availability with high scientific standards and technological innovation with peer acceptability.

Blotting, Northern↗
PubMed2006

Transcriptome profiling uncovers metabolic and regulatory processes occurring during the transition from desiccation-sensitive to desiccation-tolerant stages in Medicago truncatula seeds.

To investigate regulatory processes and protective mechanisms leading to desiccation tolerance (DT) in seeds, 16086-element microarrays were used to monitor changes in the transcriptome of desiccation-sensitive 3-mm-long radicles of Medicago truncatula seeds at different time points during incubation in a polyethylene glycol (PEG) solution at -1.7 MPa, resulting in a gradual re-establishment of DT. Gene profiling was also performed on embryos before and after the acquisition of DT during maturation. More than 1300 genes were differentially expressed during the PEG incubation. A large number of genes involved in C metabolism are expressed during the re-establishment of DT. Quantification of C reserves confirms that lipids, starch and oligosaccharides were mobilised, coinciding with the production of sucrose during the early osmotic adjustment. Several clusters of gene profiles were identified with different time-scales. Genes expressed early during the PEG incubation belonged to classes involved in early stress and adaptation responses. Interestingly, several regulatory genes typically expressed during abiotic/drought stresses were also upregulated during maturation, arguing for the partial overlap of ABA-dependent and -independent regulatory pathways involved in both drought and DT. At later time points, in parallel to the re-establishment of DT, upregulated genes are comparable with those involved in late seed maturation. Concomitantly, a massive repression of genes belonging to numerous classes occurred, including cell cycle, biogenesis, primary and energy metabolism. The re-establishment of DT in the germinated radicles appears to concur with a partial return to the quiescent state prior to germination.

Abscisic Acid↗
PubMed2006

Proteomic and transcriptomic analysis of Arabidopsis seeds: molecular evidence for successive processing of seed proteins and its implication in the stress response to sulfur nutrition.

Seed storage proteins are synthesized as sources of carbon, nitrogen and sulfur for the next generation of plants. Their composition changes according to nutritional conditions. Here, we report the precise molecular identification of seed proteins by proteomic analysis of wild-type Arabidopsis thaliana and methionine-over-accumulating mutant mto1-1 plants. The identities of 50 protein spots were determined in the protein extract of mature Arabidopsis seeds by two-dimensional (2D) gel electrophoresis and subsequent mass spectrometric analysis. Of these protein spots, 42 were identified as derived from 12S globulins or 2S albumins. These results indicate that approximately 84% of protein species in Arabidopsis seeds are derived from a few genes coding for 12S globulins and 2S albumins. Extensive mass spectrometric analysis of the 42 spots revealed that successive C-terminal degradation occurred on the 12S globulins. The feasibility of this C-terminal processing was rationalized by molecular modeling of the three-dimensional structure of 12S globulins. The C-terminal degradation at glutamic acid residues of the 12S globulin subunits was repressed under sulfur-deficient conditions. Transcriptome analysis was combined with proteomic analysis to elucidate the mechanism of changes in seed protein composition in response to sulfur deficiency. The results suggest that seed storage proteins in Arabidopsis undergo multi-layer regulation, with emphasis on post-translational modifications that enable the plant to respond to sulfur deficiency.

Arabidopsis↗
PubMed2006

UPSC-BASE--Populus transcriptomics online.

The increasing accessibility and use of microarrays in transcriptomics has accentuated the need for purpose-designed storage and analysis tools. Here we present UPSC-BASE, a database for analysis and storage of Populus DNA microarray data. A microarray analysis pipeline has also been established to allow consistent and efficient analysis (from small to large scale) of samples in various experimental designs. A range of optimized experimental protocols is provided for each step in generating the data. Within UPSC-BASE, researchers can perform standard and advanced microarray analysis procedures in a user-friendly environment. Background corrections, normalizations, quality-control tools, visualizations, hypothesis tests and export tools are provided without requirements for expert-level knowledge. Although the database has been developed primarily for handling Populus DNA microarrays, most of the tools are generic and can be used for other types of microarray. UPSC-BASE is also a repository of Populus microarray information, providing data from 21 experiments on a total of 407 microarray hybridizations in the public domain of the database. There are also an additional 10 experiments containing 347 hybridizations, where the automatically analysed data are searchable.

Databases, Genetic↗
PubMed2006

Comparative transcriptome maps: a new approach to the diagnosis of colorectal carcinoma patients using cDNA microarrays.

The progression of colorectal cancer involves accumulation of various genetic and epigenetic events that dramatically change gene expression. The aim of this study was to investigate a possible new approach to the diagnosis of colorectal carcinoma patients, based on their gene expression profiles. Human 19K cDNA microarrays were used to analyze the gene expression profiles of 18 colorectal carcinoma patients. Transcriptome maps (TMs) were analyzed to detect chromosomal regions that could serve as potential diagnostic markers for colon cancer. A comparison of TMs showed chromosome regions with conserved changes of gene expression typical of colorectal cancer in general, and also patient-specific variable regions. We identified 195 genes with significantly altered expression in colon cancer. Functional analysis of the regulated genes distinguished three main categories: biological processes, cellular components, and molecular functions. We found that different patients had chromosome regions characterized by very similar changes of gene expression, probably linked to the most fundamental events in carcinogenesis. On the other hand, variable chromosome regions can be patient-specific. The variable regions may provide further information on the individual pathogenesis and prognosis of the patient. Comparison of TMs is proposed as a tool to facilitate diagnosis and treatment planning for individual patients.

Biomarkers, Tumor↗
PubMed2004

A transcriptomics resource for wheat functional genomics.

Grain development, germination and plant development under abiotic stresses are areas of biology that are of considerable interest to the cereal community. Within the Investigating Gene Function programme we have produced the resources required to investigate alterations in the transcriptome of hexaploid wheat during these developmental processes. We have single pass sequenced the cDNAs of between 700 and 1300 randomly picked clones from each of 35 cDNA libraries representing highly specific stages of grain and plant development. Annotated sequencing results have been stored in a publicly accessible, online database at http://www.cerealsdb.uk.net. Each of the tissue stages used has also been photographed in detail, resulting in a collection of high-quality micrograph images detailing wheat grain development. These images have been collated and annotated in order to produce a web site focused on wheat development (http://www.wheatbp.net/). We have also produced high-density microarrays of a publicly available wheat unigene set based on the 35 cDNA libraries and have completed a number of microarray experiments which validate their quality.

Journal Article↗
PubMed2006

Transgenesis has less impact on the transcriptome of wheat grain than conventional breeding.

Detailed global gene expression profiles have been obtained for a series of transgenic and conventionally bred wheat lines expressing additional genes encoding HMW (high molecular weight) subunits of glutenin, a group of endosperm-specific seed storage proteins known to determine dough strength and therefore bread-making quality. Differences in endosperm and leaf transcriptome profiles between untransformed and derived transgenic lines were consistently extremely small, when analysing plants containing either transgenes only, or also marker genes. Differences observed in gene expression in the endosperm between conventionally bred material were much larger in comparison to differences between transgenic and untransformed lines exhibiting the same complements of gluten subunits. These results suggest that the presence of the transgenes did not significantly alter gene expression and that, at this level of investigation, transgenic plants could be considered substantially equivalent to untransformed parental lines.

Breeding↗
PubMed2007

Transcriptome analysis reveals season-specific rbcS gene expression profiles in diploid perennial ryegrass (Lolium perenne L.).

Perennial ryegrass (Lolium perenne L.) is a major grass species used for forage and turf throughout the world, and gains by conventional breeding have reached a plateau. Perennial ryegrass is an outcrossing, self-incompatible diploid (2n = 2x = 14) with a relatively large genome (4067 Mbp/diploid genome; Evans, G.M., Rees, H., Snell, C.L. and Sun, S. (1972) The relation between nuclear DNA amount and the duration of the mitotic cycle. Chrom. Today, 3, 24-31). Using tissues sourced from active pastures during the peak of the autumn, winter, spring and summer seasons, we analysed the ryegrass transcriptome employing a Serial Analysis of Gene Expression (SAGE) protocol, with the dual goals of understanding the seasonal changes in perennial ryegrass gene expression and enhancing our ability to select genes for genetic manipulation. A total of 159,002 14-mer SAGE tags was sequenced and mapped to the perennial ryegrass DNA database, comprising methyl-filtered (GeneThresher) and expressed sequence tag (EST) sequences. The analysis of 14,559 unique SAGE tags, which were present more than once in our SAGE library, revealed 964, 1331, 346 and 131 exclusive transcripts to autumn, winter, spring and summer, respectively. Intriguingly, our analysis of the SAGE tags revealed season-specific expression profiles for the small subunit of ribulose-1,5-bisphosphate carboxylase (Rubisco), LprbcS. The transcript level for LprbcS was highest in spring, and then decreased gradually between summer and winter. Five different copies of LprbcS were revealed in ryegrass, with one possibly producing splice variant transcripts. Two highly expressed LprbcS genes were reported, one of which was not active in autumn. Another LprbcS gene showed an inverse expression profile to the autumn inactive LprbcS in a manner to compensate the expression level.

Alternative Splicing↗
PubMed2006

Transcriptome analysis of bud burst in sessile oak (Quercus petraea).

Expression patterns of hundreds of transcripts in apical buds were monitored during bud flushing in sessile oak (Quercus petraea), in order to identify genes differentially expressed between the quiescent and active stage of bud development. Different transcriptomic techniques combining the construction of suppression subtractive hybridization (SSH) libraries and the monitoring of gene expression using macroarray and real-time reverse transcriptase polymerase chain reaction (RT-PCR) were performed to dissect bud burst, with a special emphasis on the onset of the process. We generated 801 expressed sequence tags (ESTs) derived from six developmental stages of bud burst. Macroarray experiment revealed a total of 233 unique transcripts exhibiting differential expression during the process, and a putative function was assigned to 65% of them. Cell rescue/defense-, metabolism-, protein synthesis-, cell cycle- and transcription-related transcripts were among the most regulated genes. Macroarray and real-time RT-PCR showed that several genes exhibited contrasted expressions between quiescent and swelling buds, such as a putative homologue of the transcription factor DAG2 (Dof Affecting Germination 2), previously reported to be involved in the control of seed germination in Arabidopsis thaliana. These differentially expressed genes constitute relevant candidates for signaling pathway of bud burst in trees.

Cluster Analysis↗
PubMed2006

The inflammatory transcriptome of reactive murine astrocytes and implications for their innate immune function.

Upon injury, astrocytes assume an activated state associated with the release of inflammatory mediators. To model this, we stimulated murine primary astrocytes with a complete inflammatory cytokine mix consisting of TNF-alpha, IL-1beta and IFN-gamma. We analysed the transcriptional response of 480 genes at 4 and 16 h after stimulation on a chip designed to give a representative overview over the inflammation-relevant part of the transcriptome of macrophage-like cells. The list of the 182 genes found to be significantly regulated in astrocytes revealed an intriguing co-ordinate regulation of genes linked to the biological processes of antiviral/antimicrobial defence, antigen presentation and facilitation of leucocyte invasion. The latter group was characterized by very high up-regulations of chemokine genes. We also identified regulations of a thymidylate kinase and an interferon-regulated protein with a tetratricopeptide motive, both up to now only known from macrophages. The transcriptional regulations were confirmed on the protein level by a proteomic analysis. These findings taken together suggest that activated astrocytes in brain behave similarly in many respects to inflamed macrophages in the periphery.

Animals↗
PubMed2006

Integration of transcriptomic and metabolic analyses for understanding the global responses of low-temperature winemaking fermentations.

Wine produced at low temperature is often considered to have improved sensory qualities. To investigate the effects of temperature on winemaking, the expression patterns during the industrial fermentation process carried out at 13 degrees C and 25 degrees C were compared, and correlated with physiological and biochemical data, including viability, fermentation byproducts and lipid content of the cells. From a total of 535 ORFs that were significantly differentially expressed between the 13 degrees C and 25 degrees C fermentations, two significant transcription programmes were identified. A cold-stress response was expressed at the initial stage of the fermentation, and this was followed by a transcription pattern of upregulated genes concerned with the cell cycle, growth control and maintenance in the middle and late stages of the process at 13 degrees C with respect to 25 degrees C. These expression patterns were correlated with higher cell viability at low temperature. The other relevant transcriptomic difference was that several genes implicated in cytosolic fatty acid synthesis were downregulated, while those involved in mitochondrial short-chain fatty acid synthesis were upregulated in the fermentation process conducted at 13 degrees C with respect to that at 25 degrees C. These transcriptional changes were qualitatively correlated with improved resistance to ethanol and increased production of short-chain (C(4)-C(8)) fatty acids and their corresponding esters at 13 degrees C as compared to 25 degrees C. While this increase of ethyl esters may account in part for the improved sensory quality of wine fermented at 13 degrees C, it is still unclear how the esterification of the short-chain fatty acids takes place. On the basis of its strong upregulation at 13 degrees C, we propose a possible role of IAH1 encoding an esterase/ester synthase in this process.

Cold Temperature↗