Peri-operative tobacco cessation interventions: a systematic review and meta-analysis

Tobacco smoking is associated with a substantially increased risk of postoperative complications. The peri-operative period offers a unique opportunity to support patients to stop tobacco smoking, avoid complications and improve long-term health. This systematic review provides an up-to-date summary of the evidence for tobacco cessation interventions in surgical patients. We conducted a systematic search of randomised controlled trials of tobacco cessation interventions in the peri-operative period. Quantitative synthesis of the abstinence outcomes data was by random-effects meta-analysis. The primary outcome of the meta-analysis was abstinence at the time of surgery, and the secondary outcome was abstinence at 12 months. Thirty-eight studies are included in the review (7310 randomised participants) and 26 studies are included in the meta-analysis (5969 randomised participants). Studies were pooled for subgroup analysis in two ways: by the timing of intervention delivery within the peri-operative period and by the intensity of the intervention protocol. We judged the quality of evidence as moderate, reflecting the degree of heterogeneity and the high risk of bias. Overall, peri-operative tobacco cessation interventions increased successful abstinence both at the time of surgery, risk ratio (95%CI) 1.48 (1.20-1.83), number needed to treat 7; and 12 months after surgery, risk ratio (95%CI) 1.62 (1.29-2.03), number needed to treat 9. More work is needed to inform the design and optimal delivery of interventions that are acceptable to patients and that can be incorporated into contemporary elective and urgent surgical pathways. Future trials should use standardised outcome measures.

Scoping review of mode of anaesthesia in emergency surgery

BACKGROUND

Emergency surgery encompasses more than 50 per cent of the surgical workload; however, research efforts are disproportionally low. The mode of anaesthesia used during emergency surgery may affect outcomes, but the extent of research and the impact of the different modes of anaesthesia used are unclear.

METHODS

MEDLINE and Embase were searched using scoping review methodology with a rapid systematic search strategy, identifying any study comparing locoregional (local, nerve block, subarachnoid, epidural) anaesthesia with general anaesthesia. All studies describing outcomes of emergency surgery with differing modes of anaesthesia were identified. Excluded were: studies published before 2003, studies enrolling patients aged less than 18 years and studies using sedation only.

RESULTS

Forty-two studies were identified, describing 11 surgical procedures. Most publications were retrospective cohort studies (32). A very broad range of clinical and patient-reported outcomes were described, with wide variation in the outcomes reported in different studies.

CONCLUSION

Reporting of mode of anaesthesia is inconsistent across different procedures and is often absent. There is a need for directed research efforts to improve the reporting standards of anaesthesia interventions, to understand the role of different modes of anaesthesia in specific emergency surgical procedures, and to standardize outcome reporting using core outcome sets.

Gene networks associated with non-syndromic intellectual disability

Non-syndromic intellectual disability (NS-ID) is a genetically heterogeneous disorder, with more than 200 candidate genes to date. Despite the increasing number of novel mutations detected, a relatively low number of recurrently mutated genes have been identified, highlighting the complex genetic architecture of the disorder. A systematic search of PubMed and Medline identified 245 genes harbouring non-synonymous variants, insertions or deletions, which were identified as candidate NS-ID genes from case reports or from linkage or pedigree analyses. From this list, 33 genes are common to syndromic intellectual disability (S-ID) and 58 genes are common to certain neurological and neuropsychiatric disorders that often include intellectual disability as a clinical feature. We examined the evolutionary constraint and brain expression of these gene sets, and we performed gene network and protein-protein interaction analyses using GeneGO MetaCore^TM and DAPPLE, respectively. The 245 NS-ID candidate genes were over-represented in axon guidance, synaptogenesis, cell adhesion and neurotransmission pathways, all of which are key neurodevelopmental processes for the establishment of mature neuronal circuitry in the brain. These 245 genes exhibit significantly elevated expression in human brain and are evolutionarily constrained, consistent with expectations for a brain disorder such as NS-ID that is associated with reduced fecundity. In addition, we report enrichment of dopaminergic and glutamatergic pathways for those candidate NS-ID genes that are common to S-ID and/or neurological and neuropsychiatric disorders that exhibit intellectual disability. Collectively, this study provides an overview and analysis of gene networks associated with NS-ID and suggests modulation of neurotransmission, particularly dopaminergic and glutamatergic systems as key contributors to synaptic dysfunction in NS-ID.

Bioinformatics in the plant genomic and phenomic domain: The German contribution to resources, services and perspectives

Plant genetic resources are a substantial opportunity for plant breeding, preservation and maintenance of biological diversity. As part of the German Network for Bioinformatics Infrastructure (de.NBI) the German Crop BioGreenformatics Network (GCBN) focuses mainly on crop plants and provides both data and software infrastructure which are tailored to the needs of the plant research community. Our mission and key objectives include: (1) provision of transparent access to germplasm seeds, (2) the delivery of improved workflows for plant gene annotation, and (3) implementation of bioinformatics services that link genotypes and phenotypes. This review introduces the GCBN's spectrum of web-services and integrated data resources that address common research problems in the plant genomics community.

Gender-Specific Molecular and Clinical Features Underlie Malignant Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive cancer that occurs more frequently in men, but is associated with longer survival in women. Insight into the survival advantage of female patients may advance the molecular understanding of MPM and identify therapeutic interventions that will improve the prognosis for all MPM patients. In this study, we performed whole-genome sequencing of tumor specimens from 10 MPM patients and matched control samples to identify potential driver mutations underlying MPM. We identified molecular differences associated with gender and histology. Specifically, single-nucleotide variants of BAP1 were observed in 21% of cases, with lower mutation rates observed in sarcomatoid MPM (P < 0.001). Chromosome 22q loss was more frequently associated with the epithelioid than that nonepitheliod histology (P = 0.037), whereas CDKN2A deletions occurred more frequently in nonepithelioid subtypes among men (P = 0.021) and were correlated with shorter overall survival for the entire cohort (P = 0.002) and for men (P = 0.012). Furthermore, women were more likely to harbor TP53 mutations (P = 0.004). Novel mutations were found in genes associated with the integrin-linked kinase pathway, including MYH9 and RHOA. Moreover, expression levels of BAP1, MYH9, and RHOA were significantly higher in nonepithelioid tumors, and were associated with significant reduction in survival of the entire cohort and across gender subgroups. Collectively, our findings indicate that diverse mechanisms highly related to gender and histology appear to drive MPM.

Human mesenchymal stem cells alter the gene profile of monocytes from patients with Type 2 diabetes and end-stage renal disease

AIM

Macrophage infiltration contributes to the pathogenesis of Type 2 diabetes. Mesenchymal stem cells (MSCs) possess immunomodulatory properties, making them an ideal candidate for therapeutic intervention. This study investigated whether MSCs can modulate the phenotype of monocytes isolated from Type 2 diabetic patients with end-stage renal disease.

MATERIALS & METHODS

Monocytes from control (n = 4) and Type 2 diabetic patients with end-stage renal disease (n = 5) were assessed using flow cytometry and microarray profiling, following 48 h of co-culture with MSCs.

RESULTS

Control subjects had a greater proportion of CD14(++)CD16(-) monocytes while diabetic patients had a higher proportion of CD14(++)CD16(+) and CD14(+)CD16(++) monocytes. MSCs promoted the proliferation of monocytes isolated from diabetic patients, reduced HLA-DR expression in both groups and promoted the expression of anti-inflammatory genes.

CONCLUSION

MSC-derived factors alter the polarization of monocytes isolated from healthy and diabetic subjects toward an M2 phenotype.

Impact of Screening Implementing HCV Screening of Persons Born 1945-1965: A Primary Care Case Study

BACKGROUND

In August 2012, the Centers for Disease Control and Prevention released recommendations to screen persons born from 1945 to 1965 for hepatitis C virus (HCV). In September 2012, Warm Springs Health and Wellness Center (WSHWC) initiated a quality improvement (QI) project to conduct HCV screening among all patients in this birth cohort.

METHODS

Screening rates were tracked using a nationally standardized HCV screening measure in the Indian Health Service. At the end of the project period, WSHWC staff took a brief survey to review the impact of the HCV QI Project.

RESULTS

Screening for HCV among eligible patients at WSHWC increased from 5% (47/938) in September 2012 to 76% (593/785) in September 2014. Survey data indicated that clinicians felt increased screening for HCV had a positive impact on patient communication and care.

CONCLUSIONS

Primary care clinics can successfully increase HCV screening in a relatively short time period. Age based screening recommendation may provide opportunities to increase communication with others at risk for HCV. As more patients are screened, it will be important to ensure appropriate linkage to care for HCV patients.

Programmed ribosomal frameshift alters expression of west nile virus genes and facilitates virus replication in birds and mosquitoes

West Nile virus (WNV) is a human pathogen of significant medical importance with close to 40,000 cases of encephalitis and more than 1,600 deaths reported in the US alone since its first emergence in New York in 1999. Previous studies identified a motif in the beginning of non-structural gene NS2A of encephalitic flaviviruses including WNV which induces programmed −1 ribosomal frameshift (PRF) resulting in production of an additional NS protein NS1′. We have previously demonstrated that mutant WNV with abolished PRF was attenuated in mice. Here we have extended our previous observations by showing that PRF does not appear to have a significant role in virus replication, virion formation, and viral spread in several cell lines in vitro. However, we have also shown that PRF induces an over production of structural proteins over non-structural proteins in virus-infected cells and that mutation abolishing PRF is present in ∼11% of the wild type virus population. In vivo experiments in house sparrows using wild type and PRF mutant of New York 99 strain of WNV viruses showed some attenuation for the PRF mutant virus. Moreover, PRF mutant of Kunjin strain of WNV showed significant decrease compared to wild type virus infection in dissemination of the virus from the midgut through the haemocoel, and ultimately the capacity of infected mosquitoes to transmit virus. Thus our results demonstrate an important role for PRF in regulating expression of viral genes and consequently virus replication in avian and mosquito hosts.

Programmed ribosomal frameshift (PRF) is a strategy used by some viruses to regulate expression of viral genes and/or generate additional gene products for the benefit of the virus. Encephalitic flaviruses from Japanese encephalitis virus serogroup encode PRF motif in the beginning of nonstructural gene NS2A that results in production of an additional nonstructural protein NS1′ which for West Nile virus (WNV) consists of NS1 protein with 52 amino acid addition at the C terminus. Our previous studies showed that abolishing PFR and NS1′ production attenuated WNV virulence in mice. Here we show by using wild type and PRF-deficient WNV mutant that PRF induces overproduction of structural proteins, which facilitates virus replication in birds and mosquitoes while having no advantage for virus replication in cell lines in vitro. Presence of PRF/NS1′ allowed more efficient virus dissemination in the body of mosquitoes after taking infected blood meal and subsequent accumulation of the virus in saliva to facilitate transmission. Combined with our previous data in mice, the results obtained in this study demonstrate that while having no advantage for WNV replication in vitro, PRF provides advantage for WNV replication in vivo in mammalian, avian and mosquito hosts most likely by overproducing viral structural proteins and generating NS1′.

Whole transcriptome characterization of the effects of dehydration and rehydration on Cladonia rangiferina, the grey reindeer lichen

BACKGROUND

Lichens are symbiotic organisms with a fungal and an algal or a cyanobacterial partner. Lichens inhabit some of the harshest climates on earth and most lichen species are desiccation-tolerant. Lichen desiccation-tolerance has been studied at the biochemical level and through proteomics, but the underlying molecular genetic mechanisms remain largely unexplored. The objective of our study was to examine the effects of dehydration and rehydration on the gene expression of Cladonia rangiferina.

RESULTS

Samples of C. rangiferina were collected at several time points during both the dehydration and rehydration process and the gene expression intensities were measured using a custom DNA microarray. Several genes, which were differentially expressed in one or more time points, were identified. The microarray results were validated using qRT-PCR analysis. Enrichment analysis of differentially expressed transcripts was also performed to identify the Gene Ontology terms most associated with the rehydration and dehydration process.

CONCLUSIONS

Our data identify differential expression patterns for hundreds of genes that are modulated during dehydration and rehydration in Cladonia rangiferina. These dehydration and rehydration events clearly differ from each other at the molecular level and the largest changes to gene expression are observed within minutes following rehydration. Distinct changes are observed during the earliest stage of rehydration and the mechanisms not appear to be shared with the later stages of wetting or with drying. Several of the most differentially expressed genes are similar to genes identified in previous studies that have investigated the molecular mechanisms of other desiccation-tolerant organisms. We present here the first microarray experiment for any lichen species and have for the first time studied the genetic mechanisms behind lichen desiccation-tolerance at the whole transcriptome level.

Thermoanaerobaculum aquaticum gen. nov., sp. nov., the first cultivated member of Acidobacteria subdivision 23, isolated from a hot spring

A novel bacterium was isolated from a freshwater hot spring, the Hale House Spring, located at Hot Springs National Park, Hot Springs, AR, USA. Cells of strain MP-01(T) stained Gram-negative, were rod-shaped, non-motile, strictly anaerobic and chemo-organotrophic and did not form spores. Growth occurred at 50-65 °C, with an optimum at 60 °C, at pH 6.0-8.0, with an optimum at pH 6.5-7.0, and at NaCl concentrations up to 0.5 % (w/v), with optimum growth in the absence of NaCl. Strain MP-01(T) was capable of fermentative growth on pyruvate or proteinaceous substrates as well as reducing Fe(III) and Mn(IV). Major fatty acids were iso-C15 : 0, iso-C16 : 0, anteiso-C17 : 0 and iso-C17 : 0. The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine and the major isoprenoid quinone was MK-10. In the polyamine pattern, sym-homospermidine was the predominant compound. The DNA G+C content was 62.7 mol%. Analysis of the 16S rRNA gene sequence of the isolate indicated that strain MP-01(T) represents the first reported cultivated member of subdivision 23 of the Acidobacteria. It is proposed that strain MP-01(T) represents a novel genus and species, for which the name Thermoanaerobaculum aquaticum gen. nov., sp. nov. is proposed. The type strain of Thermoanaerobaculum aquaticum is MP-01(T) ( = DSM 24856(T) = JCM 18256(T)).

Fontimonas thermophila gen. nov., sp. nov., a moderately thermophilic bacterium isolated from a freshwater hot spring, and proposal of Solimonadaceae fam. nov. to replace Sinobacteraceae Zhou et al. 2008

A novel bacterial strain designated HA-01T was isolated from a freshwater terrestrial hot spring located at Hot Springs National Park, Arkansas, USA. Cells were Gram-negative-staining, rod-shaped, aerobic, chemo-organotrophic, oxidase- and catalase-positive, non-spore-forming and motile by means of a single polar flagellum. Growth occurred at 37–60 °C, with an optimum between 45 and 50 °C, and at pH 6.5–8.5, with an optimum between pH 6.5 and 7.0. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the closest relatives of strain HA-01T were Solimonas aquatica NAA-16T (93.8 %), Solimonas flava CW-KD 4T (94.1 %), Solimonas soli DCY12T (93.1 %), Solimonas variicoloris MN28T (94.0 %), Nevskia ramosa Soe1T (91.2 %) and Hydrocarboniphaga effusa AP103T (91.1 %). Major fatty acids consisted of C16 : 0, iso-C16 : 0, C16 : 1ω5c and summed feature 8 (C18 : 1ω9c, C18 : 1ω7c and C18 : 1ω6c). Polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine, and the major isoprenoid quinone was Q-8. The DNA G+C content was 64.4 mol%. Based on phylogenetic, phenotypic and chemotaxonomic evidence, it is proposed that strain HA-01T represents a novel species in a new genus for which the name Fontimonas thermophila gen. nov., sp. nov. is proposed. The type strain of the type species is HA-01T ( = DSM 23609T = CCUG 59713T). A new family, Solimonadaceae fam. nov., is also proposed to replace Sinobacteriaceae Zhou et al. 2008.

Characterization of a transcriptome from a non-model organism, Cladonia rangiferina, the grey reindeer lichen, using high-throughput next generation sequencing and EST sequence data

BACKGROUND

Lichens are symbiotic organisms that have a remarkable ability to survive in some of the most extreme terrestrial climates on earth. Lichens can endure frequent desiccation and wetting cycles and are able to survive in a dehydrated molecular dormant state for decades at a time. Genetic resources have been established in lichen species for the study of molecular systematics and their taxonomic classification. No lichen species have been characterised yet using genomics and the molecular mechanisms underlying the lichen symbiosis and the fundamentals of desiccation tolerance remain undescribed. We report the characterisation of a transcriptome of the grey reindeer lichen, Cladonia rangiferina, using high-throughput next-generation transcriptome sequencing and traditional Sanger EST sequencing data.

RESULTS

Altogether 243,729 high quality sequence reads were de novo assembled into 16,204 contigs and 49,587 singletons. The genome of origin for the sequences produced was predicted using Eclat with sequences derived from the axenically grown symbiotic partners used as training sequences for the classification model. 62.8% of the sequences were classified as being of fungal origin while the remaining 37.2% were predicted as being of algal origin. The assembled sequences were annotated by BLASTX comparison against a non-redundant protein sequence database with 34.4% of the sequences having a BLAST match. 29.3% of the sequences had a Gene Ontology term match and 27.9% of the sequences had a domain or structural match following an InterPro search. 60 KEGG pathways with more than 10 associated sequences were identified.

CONCLUSIONS

Our results present a first transcriptome sequencing and de novo assembly for a lichen species and describe the ongoing molecular processes and the most active pathways in C. rangiferina. This brings a meaningful contribution to publicly available lichen sequence information. These data provide a first glimpse into the molecular nature of the lichen symbiosis and characterise the transcriptional space of this remarkable organism. These data will also enable further studies aimed at deciphering the genetic mechanisms behind lichen desiccation tolerance.

Nitrospira-dominated biofilm within a thermal artesian spring: a case for nitrification-driven primary production in a geothermal setting

Water chemistry, energetic modeling, and molecular analyses were combined to investigate the microbial ecology of a biofilm growing in a thermal artesian spring within Hot Springs National Park, AR. This unique fresh water spring has a low dissolved chemical load and is isolated from both light and direct terrestrial carbon input - resulting in an oligotrophic ecosystem limited for fixed carbon and electron donors. Evaluation of energy yields of lithotrophic reactions putatively linked to autotrophy identified the aerobic oxidation of methane, hydrogen, sulfide, ammonia, and nitrite as the most exergonic. Small subunit (SSU) rRNA gene libraries from biofilm revealed a low-diversity microbial assemblage populated by bacteria and archaea at a gene copy ratio of 45:1. Members of the bacterial family 'Nitrospiraceae', known for their autotrophic nitrite oxidation, dominated the bacterial SSU rRNA gene library (approximately 45%). Members of the Thaumarchaeota ThAOA/HWCGIII (>96%) and Thaumarchaeota Group I.1b (2.5%), which both contain confirmed autotrophic ammonia oxidizers, dominated the archaeal SSU rRNA library. Archaea appear to dominate among the ammonia oxidizers, as only ammonia monooxygenase subunit A (amoA) genes belonging to members of the Thaumarchaeota were detected. The geochemical, phylogenetic, and genetic data support a model that describes a novel thermophilic biofilm built largely by an autotrophic nitrifying microbial assemblage. This is also the first observation of 'Nitrospiraceae' as the dominant organisms within a geothermal environment.

Optimization and comparison of different methods for RNA isolation for cDNA library construction from the reindeer lichen Cladonia rangiferina

BACKGROUND

The reindeer lichen is the product of a mutualistic relationship between a fungus and an algae. Lichen demonstrate a remarkable capacity to tolerate dehydration. This tolerance is driven by a variety of biochemical processes and the accumulation of specific secondary metabolites that may be of relevance to the pharmaceutical, biotechnology and agriculture industries. These protective metabolites hinder in vitro enzymatic reactions required in cDNA synthesis. Along with the low concentrations of RNA present within lichen tissues, the process of creating a cDNA library is technically challenging.

FINDINGS

An evaluation of existing commercial and published protocols for RNA extraction from plant or fungal tissues has been performed and experimental conditions have been optimised to balance the need for the highest quality total ribonucleotides and the constraints of budget, time and human resources.

CONCLUSION

We present a protocol that balances inexpensive RNA extraction methods with commercial RNA clean-up kits to yield sufficient RNA for cDNA library construction. Evaluation of the protocol and the construction of, and sampling from, a cDNA library is used to demonstrate the suitability of the RNA extraction method for expressed sequence tag production.

Comparative mapping of DNA sequences in rye (Secale cereale L.) in relation to the rice genome

The rice genome has proven a valuable resource for comparative approaches to address individual genomic regions in Triticeae species at the molecular level. To exploit this resource for rye genetics and breeding, an inventory was made of EST-derived markers with known genomic positions in rye, which were related with those in rice. As a first inventory set, 92 EST-SSR markers were mapped which had been drawn from a non-redundant rye EST collection representing 5,423 unigenes and 2.2 Mb of DNA. Using a BC1 mapping population which involved an exotic rye accession as donor parent, these EST-SSR markers were arranged in a linkage map together with 25 genomic SSR markers as well as 131 AFLP and four STS markers. This map comprises seven linkage groups corresponding to the seven rye chromosomes and covers 724 cM of the rye genome. For comparative studies, additional inventory sets of EST-based markers were included which originated from the rye-mapping data published by other authors. Altogether, 502 EST-based markers with known chromosomal localizations in rye were used for BlastN search and 334 of them could be in silico mapped in the rice genome. Additionally, 14 markers were included which lacked sequence information but had been genetically mapped in rice. Based on the 348 markers, each of the seven rye chromosomes could be aligned with distinct portions of the rice genome, providing improved insight into the status of the rye-rice genome relationships. Furthermore, the aligned markers provide genomic anchor points between rye and rice, enabling the identification of conserved ortholog set markers for rye. Perspectives of rice as a model for genome analysis in rye are discussed.

Microarray analysis identifies candidate genes for key roles in coral development

BACKGROUND

Anthozoan cnidarians are amongst the simplest animals at the tissue level of organization, but are surprisingly complex and vertebrate-like in terms of gene repertoire. As major components of tropical reef ecosystems, the stony corals are anthozoans of particular ecological significance. To better understand the molecular bases of both cnidarian development in general and coral-specific processes such as skeletogenesis and symbiont acquisition, microarray analysis was carried out through the period of early development - when skeletogenesis is initiated, and symbionts are first acquired.

RESULTS

Of 5081 unique peptide coding genes, 1084 were differentially expressed (P <or= 0.05) in comparisons between four different stages of coral development, spanning key developmental transitions. Genes of likely relevance to the processes of settlement, metamorphosis, calcification and interaction with symbionts were characterised further and their spatial expression patterns investigated using whole-mount in situ hybridization.

CONCLUSION

This study is the first large-scale investigation of developmental gene expression for any cnidarian, and has provided candidate genes for key roles in many aspects of coral biology, including calcification, metamorphosis and symbiont uptake. One surprising finding is that some of these genes have clear counterparts in higher animals but are not present in the closely-related sea anemone Nematostella. Secondly, coral-specific processes (i.e. traits which distinguish corals from their close relatives) may be analogous to similar processes in distantly related organisms. This first large-scale application of microarray analysis demonstrates the potential of this approach for investigating many aspects of coral biology, including the effects of stress and disease.

Expression profiling of the lignin biosynthetic pathway in Norway spruce using EST sequencing and real-time RT-PCR

Lignin biosynthesis is a major carbon sink in gymnosperms and woody angiosperms. Many of the enzymes involved are encoded for by several genes, some of which are also related to the biosynthesis of other phenylpropanoids. In this study, we aimed at the identification of those gene family members that are responsible for developmental lignification in Norway spruce (Picea abies (L.) Karst.). Gene expression across the whole lignin biosynthetic pathway was profiled using EST sequencing and quantitative real-time RT-PCR. Stress-induced lignification during bending stress and Heterobasidion annosum infection was also studied. Altogether 7,189 ESTs were sequenced from a lignin forming tissue culture and developing xylem of spruce, and clustered into 3,831 unigenes. Several paralogous genes were found for both monolignol biosynthetic and polymerisation-related enzymes. Real-time RT-PCR results highlighted the set of monolignol biosynthetic genes that are likely to be responsible for developmental lignification in Norway spruce. Potential genes for monolignol polymerisation were also identified. In compression wood, mostly the same monolignol biosynthetic gene set was expressed, but peroxidase expression differed from the vertically grown control. Pathogen infection in phloem resulted in a general up-regulation of the monolignol biosynthetic pathway, and in an induction of a few new gene family members. Based on the up-regulation under both pathogen attack and in compression wood, PaPAL2, PaPX2 and PaPX3 appeared to have a general stress-induced function.

Characterization of an 18,166 EST dataset for cassava (Manihot esculenta Crantz) enriched for drought-responsive genes

Cassava (Manihot esculenta Crantz) is a staple food for over 600 million people in the tropics and subtropics and is increasingly used as an industrial crop for starch production. Cassava has a high growth rate under optimal conditions but also performs well in drought-prone areas and on marginal soils. To increase the tools for understanding and manipulating drought tolerance in cassava, we generated expressed sequence tags (ESTs) from normalized cDNA libraries prepared from dehydration-stressed and control well-watered tissues. Analysis of a total of 18,166 ESTs resulted in the identification of 8,577 unique gene clusters (5,383 singletons and 3,194 clusters). Functional categories could be assigned to 63% of the unigenes, while another approximately 11% were homologous to hypothetical genes with unclear functions. The remaining approximately 26% were not significantly homologous to sequences in public databases suggesting that some may be novel and putatively specific to cassava. The dehydration-stressed library uncovered numerous ESTs with recognized roles in drought-responses, including those that encode late-embryogenesis-abundant proteins thought to confer osmoprotective functions during water stress, transcription factors, heat-shock proteins as well as proteins involved in signal transduction and oxidative stress. The unigene clusters were screened for short tandem repeats for further development as microsatellite markers. A total of 592 clusters contained 646 repeats, representing 3.3% of the ESTs queried. The ESTs presented here are the first dehydration stress transcriptome of cassava and can be utilized for the development of microarrays and gene-derived molecular markers to further dissect the molecular basis of drought tolerance in cassava.

Analysis of EST sequences suggests recent origin of allotetraploid colonial and creeping bentgrasses

Advances in plant genomics have permitted the analysis of several members of the grass family, including the major domesticated species, and provided new insights into the evolution of the major crops on earth. Two members, colonial bentgrass (Agrostis capillaris L.) and creeping bentgrass (A. stolonifera L.) have only recently been domesticated and provide an interesting case of polyploidy and comparison to crops that have undergone human selection for thousands of years. As an initial step of characterizing these genomes, we have sampled roughly 10% of their gene content, thereby also serving as a starting point for the construction of their physical and genetic maps. Sampling mRNA from plants subjected to environmental stress showed a remarkable increase in transcription of transposable elements. Both colonial and creeping bentgrass are allotetraploids and are considered to have one genome in common, designated the A2 genome. Analysis of conserved genes present among the ESTs suggests the colonial and creeping bentgrass A2 genomes diverged from a common ancestor approximately 2.2 million years ago (MYA), thereby providing an enhanced evolutionary zoom in respect to the origin of maize, which formed 4.8 MYA, and tetraploid wheat, which formed only 0.5 MYA and is the progenitor of domesticated hexaploid wheat.

Separation of sequences from host-pathogen interface using triplet nucleotide frequencies

The identification of genes involved in host-pathogen interactions is important for the elucidation of mechanisms of disease resistance and host susceptibility. A traditional way to classify the origin of genes sampled from a pool of mixed cDNA is through sequence similarity to known genes from either the pathogen or host organism or other closely related species. This approach does not work when the identified sequence has no close homologues in the sequence databases. In our previous studies, we classified genes using their codon frequencies. This method, however, explicitly required the prediction of CDS regions and thus could not be applied to sequences composed from the non-coding regions of genes. In this study, we show that the use of sliding-window triplet frequencies extends the application of the algorithm to both coding and non-coding sequences and also increases the prediction accuracy of a Support Vector Machine classifier from 95.6+/-0.3 to 96.5+/-0.2. Thus the use of the triplet frequencies increased the prediction accuracy of the new method by more than 20% compared to our previous approach. A functional analysis of sequences detected gene families having significantly higher or lower probability to be correctly classified compared to the average accuracy of the method is described. The server to perform classification of EST sequences using triplet frequencies is available at (URL: http://mips.gsf.de/proj/est3).

Construction, database integration, and application of an Oenothera EST library

Coevolution of cellular genetic compartments is a fundamental aspect in eukaryotic genome evolution that becomes apparent in serious developmental disturbances after interspecific organelle exchanges. The genus Oenothera represents a unique, at present the only available, resource to study the role of the compartmentalized plant genome in diversification of populations and speciation processes. An integrated approach involving cDNA cloning, EST sequencing, and bioinformatic data mining was chosen using Oenothera elata with the genetic constitution nuclear genome AA with plastome type I. The Gene Ontology system grouped 1621 unique gene products into 17 different functional categories. Application of arrays generated from a selected fraction of ESTs revealed significantly differing expression profiles among closely related Oenothera species possessing the potential to generate fertile and incompatible plastid/nuclear hybrids (hybrid bleaching). Furthermore, the EST library provides a valuable source of PCR-based polymorphic molecular markers that are instrumental for genotyping and molecular mapping approaches.

Genetic screen for signal peptides in Hydra reveals novel secreted proteins and evidence for non-classical protein secretion

We have screened a Hydra cDNA library for sequences encoding N-terminal signal peptides using the yeast invertase secretion vector pSUC [Jacobs et al., 1997. A genetic selection for isolating cDNAs encoding secreted proteins. Gene 198, 289-296]. We isolated and sequenced 907 positive clones; 88% encoded signal peptides; 12% lacked signal peptides. By searching the Hydra EST database we identified full-length sequences for the selected clones. These encoded 37 known proteins with signal peptides and 40 novel Hydra-specific proteins with signal peptides. Localization of two signal peptide-containing sequences, VEGF and ferritin, to the secretory pathway was confirmed with GFP fusion proteins. In addition, we isolated 105 clones which lacked signal peptides but which supported invertase secretion from yeast. Isolation of plasmids from these clones and retransformation in invertase-negative yeast cells confirmed the phenotype. A GFP fusion protein of one such clone encoding the foot morphogen pedibin was localized to the cytoplasm in transfected Hydra cells and did not enter the ER/Golgi secretory pathway. Secretion of pedibin and other proteins lacking signal peptides appears to occur by a non-classical protein secretion route.

Prospecting for pig single nucleotide polymorphisms in the human genome: have we struck gold?

Gene-to-gene variation in the frequency of single nucleotide polymorphisms (SNPs) has been observed in humans, mice, rats, primates and pigs, but a relationship across species in this variation has not been described. Here, the frequency of porcine coding SNPs (cSNPs) identified by in silico methods, and the frequency of murine cSNPs, were compared with the frequency of human cSNPs across homologous genes. From 150,000 porcine expressed sequence tag (EST) sequences, a total of 452 SNP-containing sequence clusters were found, totalling 1394 putative SNPs. All the clustered porcine EST annotations and SNP data have been made publicly available at http://sputnik.btk.fi/project?name=swine. Human and murine cSNPs were identified from dbSNP and were characterized as either validated or total number of cSNPs (validated plus non-validated) for comparison purposes. The correlation between in silico pig cSNP and validated human cSNP densities was found to be 0.77 (p < 0.00001) for a set of 25 homologous genes, while a correlation of 0.48 (p < 0.0005) was found for a primarily random sample of 50 homologous human and mouse genes. This is the first evidence of conserved gene-to-gene variability in cSNP frequency across species and indicates that site-directed screening of porcine genes that are homologous to cSNP-rich human genes may rapidly advance cSNP discovery in pigs.

A wing expressed sequence tag resource for Bicyclus anynana butterflies, an evo-devo model

BACKGROUND

Butterfly wing color patterns are a key model for integrating evolutionary developmental biology and the study of adaptive morphological evolution. Yet, despite the biological, economical and educational value of butterflies they are still relatively under-represented in terms of available genomic resources. Here, we describe an Expression Sequence Tag (EST) project for Bicyclus anynana that has identified the largest available collection to date of expressed genes for any butterfly.

RESULTS

By targeting cDNAs from developing wings at the stages when pattern is specified, we biased gene discovery towards genes potentially involved in pattern formation. Assembly of 9,903 ESTs from a subtracted library allowed us to identify 4,251 genes of which 2,461 were annotated based on BLAST analyses against relevant gene collections. Gene prediction software identified 2,202 peptides, of which 215 longer than 100 amino acids had no homology to any known proteins and, thus, potentially represent novel or highly diverged butterfly genes. We combined gene and Single Nucleotide Polymorphism (SNP) identification by constructing cDNA libraries from pools of outbred individuals, and by sequencing clones from the 3' end to maximize alignment depth. Alignments of multi-member contigs allowed us to identify over 14,000 putative SNPs, with 316 genes having at least one high confidence double-hit SNP. We furthermore identified 320 microsatellites in transcribed genes that can potentially be used as genetic markers.

CONCLUSION

Our project was designed to combine gene and sequence polymorphism discovery and has generated the largest gene collection available for any butterfly and many potential markers in expressed genes. These resources will be invaluable for exploring the potential of B. anynana in particular, and butterflies in general, as models in ecological, evolutionary, and developmental genetics.

Spatiotemporal expression control correlates with intragenic scaffold matrix attachment regions (S/MARs) in Arabidopsis thaliana

Scaffold/matrix attachment regions (S/MARs) are essential for structural organization of the chromatin within the nucleus and serve as anchors of chromatin loop domains. A significant fraction of genes in Arabidopsis thaliana contains intragenic S/MAR elements and a significant correlation of S/MAR presence and overall expression strength has been demonstrated. In this study, we undertook a genome scale analysis of expression level and spatiotemporal expression differences in correlation with the presence or absence of genic S/MAR elements. We demonstrate that genes containing intragenic S/MARs are prone to pronounced spatiotemporal expression regulation. This characteristic is found to be even more pronounced for transcription factor genes. Our observations illustrate the importance of S/MARs in transcriptional regulation and the role of chromatin structural characteristics for gene regulation. Our findings open new perspectives for the understanding of tissue- and organ-specific regulation of gene expression.

Scaffold/matrix attachment regions (S/MARs) are AT-rich DNA sequences that mediate structural organization of the chromatin within the nucleus. These elements constitute anchor points of the DNA for the chromatin scaffold and serve to organize the chromatin into structural domains. Studies on individual genes led to the conclusion that the dynamic and complex organization of the chromatin mediated by S/MAR elements plays an important role in the regulation of gene expression. In addition to intergenic S/MARs, which likely exert import insulator effects, more than 2,000 intragenic S/MARs have been shown to be present within the Arabidopsis genome. In this study, the authors set out to analyze the effects of these intragenic S/MAR elements on the regulation of the genes affected. Making use of exhaustive and multidimensional expression datasets available for Arabidopsis, the authors analyzed overall expression differences and correlation of intragenic S/MARs with spatiotemporal expression of genes. On a genome scale, pronounced tissue- and organ-specific and developmental expression patterns of S/MAR-containing genes have been detected. Notably, transcription factor genes contain a significant higher portion of S/MARs. The pronounced difference in expression characteristics of S/MAR-containing genes emphasizes their functional importance and the importance of structural chromosomal characteristics for gene regulation in plants as well as within other eukaryotes.

Gene expression and metabolite profiling of Populus euphratica growing in the Negev desert

BACKGROUND

Plants growing in their natural habitat represent a valuable resource for elucidating mechanisms of acclimation to environmental constraints. Populus euphratica is a salt-tolerant tree species growing in saline semi-arid areas. To identify genes involved in abiotic stress responses under natural conditions we constructed several normalized and subtracted cDNA libraries from control, stress-exposed and desert-grown P. euphratica trees. In addition, we identified several metabolites in desert-grown P. euphratica trees.

RESULTS

About 14,000 expressed sequence tag (EST) sequences were obtained with a good representation of genes putatively involved in resistance and tolerance to salt and other abiotic stresses. A P. euphratica DNA microarray with a uni-gene set of ESTs representing approximately 6,340 different genes was constructed. The microarray was used to study gene expression in adult P. euphratica trees growing in the desert canyon of Ein Avdat in Israel. In parallel, 22 selected metabolites were profiled in the same trees.

CONCLUSION

Of the obtained ESTs, 98% were found in the sequenced P. trichocarpa genome and 74% in other Populus EST collections. This implies that the P. euphratica genome does not contain different genes per se, but that regulation of gene expression might be different and that P. euphratica expresses a different set of genes that contribute to adaptation to saline growth conditions. Also, all of the five measured amino acids show increased levels in trees growing in the more saline soil.

Maintenance of ancestral complexity and non-metazoan genes in two basal cnidarians

Cnidarians are among the simplest extant animals; however EST analyses reveal that they have a remarkably high level of genetic complexity. In this article, we show that the full diversity of metazoan signaling pathways is represented in this phylum, as are antagonists previously known only in chordates. Many of the cnidarian ESTs match genes previously known only in non-animal kingdoms. At least some of these represent ancient genes lost by all bilaterians examined so far, rather than genes gained by recent lateral gene transfer.

A 6374 unigene set corresponding to low abundance transcripts expressed following fertilization in Solanum chacoense Bitt, and characterization of 30 receptor-like kinases

In order to characterize regulatory genes that are expressed in ovule tissues after fertilization we have undertaken an EST sequencing project in Solanum chacoense, a self-incompatible wild potato species. Two cDNA libraries made from ovule tissues covering embryo development from zygote to late torpedo-stage were constructed and plated at high density on nylon membranes. To decrease EST redundancy and enrich for transcripts corresponding to weakly expressed genes a self-probe subtraction method was used to select the colonies harboring the genes to be sequenced. 7741 good sequences were obtained and, from these, 6374 unigenes were isolated. Thus, the self-probe subtraction resulted in a strong enrichment in singletons, a decrease in the number of clones per contigs, and concomitantly, an enrichment in the total number of unigenes obtained (82%). To gain insights into signal transduction events occurring during embryo development all the receptor-like kinases (or protein receptor kinases) were analyzed by quantitative real-time RT-PCR. Interestingly, 28 out of the 30 RLK isolated were predominantly expressed in ovary tissues or young developing fruits, and 23 were transcriptionaly induced following fertilization. Thus, the self-probe subtraction did not select for genes weakly expressed in the target tissue while being highly expressed elsewhere in the plant. Of the receptor-like kinases (RLK) genes isolated, the leucine-rich repeat (LRR) family of RLK was by far the most represented with 25 members covering 11 LRR classes.

Eclair--a web service for unravelling species origin of sequences sampled from mixed host interfaces

The identification of the genes that participate at the biological interface of two species remains critical to our understanding of the mechanisms of disease resistance, disease susceptibility and symbiosis. The sequencing of complementary DNA (cDNA) libraries prepared from the biological interface between two organisms provides an inexpensive way to identify the novel genes that may be expressed as a cause or consequence of compatible or incompatible interactions. Sequence classification and annotation of species origin typically use an orthology-based approach and require access to large portions of either genome, or a close relative. Novel species- or clade-specific sequences may have no counterpart within existing databases and remain ambiguous features. Here we present a web-service, Eclair, which utilizes support vector machines for the classification of the origin of expressed sequence tags stemming from mixed host cDNA libraries. In addition to providing an interface for the classification of sequences, users are presented with the opportunity to train a model to suit their preferred species pair. Eclair is freely available at http://eclair.btk.fi.

PlantMarkers--a database of predicted molecular markers from plants

Molecular markers are required in a broad spectrum of gene screening approaches, ranging from gene-mapping within traditional ‘forward’-genetics approaches through QTL identification studies to genotyping and haplotyping studies. As we enter the post-genomics era, the need for genetic markers does not diminish, even in the species with fully sequenced genomes. PlantMarkers is a genetic marker database that contains a comprehensive pool of predicted molecular markers. We have adopted contemporary techniques to identify putative single nucleotide polymorphism (SNP), simple sequence repeat (SSR) and conserved orthologue set markers. A systematic approach to identify as broad a range of putative markers has been undertaken by screening the available openSputnik unigene consensus sequences from over 50 plant species. A web presence at http://markers.btk.fi provides functionality so that a user may search for species-specific markers on the basis of many specific criteria not limited to non-synonymous SNPs segregating between different varieties or measured polymorphic SSRs. Feedback forms are provided with all sequence entries to enable inclusion of, for example, map location for markers validated by the research community.

openSputnik--a database to ESTablish comparative plant genomics using unsaturated sequence collections

The public expressed sequence tag collections are continually being enriched with high-quality sequences that represent an ever-expanding range of taxonomically diverse plant species. While these sequence collections provide biased insight into the populations of expressed genes available within individual species and their associated tissues, the information is conceivably of wider relevance in a comparative context. When we consider the available expressed sequence tag (EST) collections of summer 2004, most of the major plant taxonomic clades are at least superficially represented. Investigation of the five million available plant ESTs provides a wealth of information that has applications in modelling the routes of plant genome evolution and the identification of lineage-specific genes and gene families. Over four million ESTs from over 50 distinct plant species have been collated within an EST analysis pipeline called openSputnik. The ESTs were resolved down into approximately one million unigene sequences. These have been annotated using orthology-based annotation transfer from reference plant genomes and using a variety of contemporary bioinformatics methods to assign peptide, structural and functional attributes. The openSputnik database is available at http://sputnik.btk.fi.

Analysis of the floral transcriptome uncovers new regulators of organ determination and gene families related to flower organ differentiation in Gerbera hybrida (Asteraceae)

Development of composite inflorescences in the plant family Asteraceae has features that cannot be studied in the traditional model plants for flower development. In Gerbera hybrida, inflorescences are composed of morphologically different types of flowers tightly packed into a flower head (capitulum). Individual floral organs such as pappus bristles (sepals) are developmentally specialized, stamens are aborted in marginal flowers, petals and anthers are fused structures, and ovaries are located inferior to other floral organs. These specific features have made gerbera a rewarding target of comparative studies. Here we report the analysis of a gerbera EST database containing 16,994 cDNA sequences. Comparison of the sequences with all plant peptide sequences revealed 1656 unique sequences for gerbera not identified elsewhere within the plant kingdom. Based on the EST database, we constructed a cDNA microarray containing 9000 probes and have utilized it in identification of flower-specific genes and abundantly expressed marker genes for flower scape, pappus, stamen, and petal development. Our analysis revealed several regulatory genes with putative functions in flower-organ development. We were also able to associate a number of abundantly and specifically expressed genes with flower-organ differentiation. Gerbera is an outcrossing species, for which genetic approaches to gene discovery are not readily amenable. However, reverse genetics with the help of gene transfer has been very informative. We demonstrate here the usability of the gerbera microarray as a reliable new tool for identifying novel genes related to specific biological questions and for large-scale gene expression analysis.

Support vector machines for separation of mixed plant-pathogen EST collections based on codon usage

MOTIVATION

Discovery of host and pathogen genes expressed at the plant-pathogen interface often requires the construction of mixed libraries that contain sequences from both genomes. Sequence identification requires high-throughput and reliable classification of genome origin. When using single-pass cDNA sequences difficulties arise from the short sequence length, the lack of sufficient taxonomically relevant sequence data in public databases and ambiguous sequence homology between plant and pathogen genes.

RESULTS

A novel method is described, which is independent of the availability of homologous genes and relies on subtle differences in codon usage between plant and fungal genes. We used support vector machines (SVMs) to identify the probable origin of sequences. SVMs were compared to several other machine learning techniques and to a probabilistic algorithm (PF-IND) for expressed sequence tag (EST) classification also based on codon bias differences. Our software (Eclat) has achieved a classification accuracy of 93.1% on a test set of 3217 EST sequences from Hordeum vulgare and Blumeria graminis, which is a significant improvement compared to PF-IND (prediction accuracy of 81.2% on the same test set). EST sequences with at least 50 nt of coding sequence can be classified using Eclat with high confidence. Eclat allows training of classifiers for any host-pathogen combination for which there are sufficient classified training sequences.

AVAILABILITY

Eclat is freely available on the Internet (http://mips.gsf.de/proj/est) or on request as a standalone version.

CONTACT

friedel@informatik.uni-muenchen.de.

Identification of NdhL and Ssl1690 (NdhO) in NDH-1L and NDH-1M complexes of Synechocystis sp. PCC 6803

The subunit compositions of two types of NAD(P)H dehydrogenase complexes of Synechocystis sp. PCC 6803, NDH-1L and NDH-1M, were studied by two-dimensional blue-native/SDS-PAGE followed by electrospray tandem mass spectrometry. Fifteen proteins were observed in NDH-1L including hydrophilic subunits (NdhH, -K, -I, -J, -M, and -N) and hydrophobic subunits (NdhA, -B, -E, -G, -D1, and -F1). In addition, NdhL and a novel subunit, Ssl1690 (designated NdhO), were shown to be components of this complex. All subunits mentioned above were present in the NDH-1M complex except NdhD1 and NdhF1. NdhL and Ssl1690 (NdhO) were homologous to hypothetical proteins encoded by genomic DNA in higher plants, suggesting that chloroplast NDH-1 complexes contain related subunits. Diagnostic sequence motifs were found for both NdhL and NdhO homologous proteins. Analysis of ndhL deletion mutant (M9) revealed the presence of assembled NDH-1L and NDH-1M complexes, but these complexes appear to be functionally impaired in the absence of NdhL. Both NDH-1 complexes were absent in the ndhB deletion mutant (M55).

Characterization of the maize endosperm transcriptome and its comparison to the rice genome

The cereal endosperm is a major organ of the seed and an important component of the world's food supply. To understand the development and physiology of the endosperm of cereal seeds, we focused on the identification of genes expressed at various times during maize endosperm development. We constructed several cDNA libraries to identify full-length clones and subjected them to a twofold enrichment. A total of 23,348 high-quality sequence-reads from 5'- and 3'-ends of cDNAs were generated and assembled into a unigene set representing 5326 genes with paired sequence-reads. Additional sequencing yielded a total of 3160 (59%) completely sequenced, full-length cDNAs. From 5326 unigenes, 4139 (78%) can be aligned with 5367 predicted rice genes and by taking only the "best hit" be mapped to 3108 positions on the rice genome. The 22% unigenes not present in rice indicate a rapid change of gene content between rice and maize in only 50 million years. Differences in rice and maize gene numbers also suggest that maize has lost a large number of duplicated genes following tetraploidization. The larger number of gene copies in rice suggests that as many as 30% of its genes arose from gene amplification, which would extrapolate to a significant proportion of the estimated 44,027 candidate genes of its entire genome. Functional classification of the maize endosperm unigene set indicated that more than a fourth of the novel functionally assignable genes found in this study are involved in carbohydrate metabolism, consistent with its role as a storage organ.

Large-scale analysis of the barley transcriptome based on expressed sequence tags

To provide resources for barley genomics, 110,981 expressed sequence tags (ESTs) were generated from 22 cDNA libraries representing tissues at various developmental stages. This EST collection corresponds to approximately one-third of the 380,000 publicly available barley ESTs. Clustering and assembly resulted in 14,151 tentative consensi (TCs) and 11 073 singletons, altogether representing 25 224 putatively unique sequences. Of these, 17.5% showed no significant similarity to other barley ESTs present in dbEST. More than 41% of all barley genes are supposed to belong to multigene families and approximately 4% of the barley genes undergo alternative splicing. Based on the functional annotation of the set of unique sequences, the functional category 'Energy' was further analysed to reveal tissue- and stage-specific differences in gene expression. Hierarchical clustering of 362 differentially expressed TCs resulted in the identification of seven major clusters. The clusters reflect biochemical pathways predominantly activated in specific tissues and at various developmental stages. During seed germination glycolysis could be identified as the most predominant biochemical pathway. Germination-specific glycolysis is characterized by the coordinated expression of phosphoenolpyruvate carboxylase and phosphoenolpyruvate carboxykinase, whose antagonistic actions possibly regulate the flux of amino acids into protein biosynthesis and gluconeogenesis respectively. The expression of defence-related and antioxidant genes during germination might be controlled by the ethylene-signalling pathway as concluded from the coordinated expression of those genes and the transcription factors (TF) EIN3 and EREBPG. Moreover, because of their predominant expression in germinating seeds, TF of the AP2 and MYB type are presumably major regulators of germination.

Genome-wide in silico mapping of scaffold/matrix attachment regions in Arabidopsis suggests correlation of intragenic scaffold/matrix attachment regions with gene expression

We carried out a genome-wide prediction of scaffold/matrix attachment regions (S/MARs) in Arabidopsis. Results indicate no uneven distribution on the chromosomal level but a clear underrepresentation of S/MARs inside genes. In cases where S/MARs were predicted within genes, these intragenic S/MARs were preferentially located within the 5'-half, most prominently within introns 1 and 2. Using Arabidopsis whole-genome expression data generated by the massively parallel signature sequencing methodology, we found a negative correlation between S/MAR-containing genes and transcriptional abundance. Expressed sequence tag data correlated the same way with S/MAR-containing genes. Thus, intragenic S/MARs show a negative correlation with transcription level. For various genes it has been shown experimentally that S/MARs can function as transcriptional regulators and that they have an implication in stabilizing expression levels within transgenic plants. On the basis of a genome-wide in silico S/MAR analysis, we found a significant correlation between the presence of intragenic S/MARs and transcriptional down-regulation.

Snipping polymorphisms from large EST collections in barley (Hordeum vulgare L.)

The public EST (expressed sequence tag) databases represent an enormous but heterogeneous repository of sequences, including many from a broad selection of plant species and a wide range of distinct varieties. The significant redundancy within large EST collections makes them an attractive resource for rapid pre-selection of candidate sequence polymorphisms. Here we present a strategy that allows rapid identification of candidate SNPs in barley (Hordeum vulgare L.) using publicly available EST databases. Analysis of 271,630 EST sequences from different cDNA libraries, representing 23 different barley varieties, resulted in the generation of 56,302 tentative consensus sequences. In all, 8171 of these unigene sequences are members of clusters with six or more ESTs. By applying a novel SNP detection algorithm (SNiPpER) to these sequences, we identified 3069 candidate inter-varietal SNPs. In order to verify these candidate SNPs, we selected a small subset of 63 present in 36 ESTs. Of the 63 SNPs selected, we were able to validate 54 (86%) using a direct sequencing approach. For further verification, 28 ESTs were mapped to distinct loci within the barley genome. The polymorphism information content (PIC) and nucleotide diversity (pi) values of the SNPs identified by the SNiPpER algorithm are significantly higher than those that were obtained by random sequencing. This demonstrates the efficiency of our strategy for SNP identification and the cost-efficient development of EST-based SNP-markers.

Expressed sequence tags: alternative or complement to whole genome sequences?

Over three million sequences from approximately 200 plant species have been deposited in the publicly available plant expressed sequence tag (EST) sequence databases. Many of the ESTs have been sequenced as an alternative to complete genome sequencing or as a substrate for cDNA array-based expression analyses. This creates a formidable resource from both biodiversity and gene-discovery standpoints. Bioinformatics-based sequence analysis tools have extended the scope of EST analysis into the fields of proteomics, marker development and genome annotation. Although EST collections are certainly no substitute for a whole genome scaffold, this "poor man's genome" resource forms the core foundations for various genome-scale experiments within the as yet unsequenceable plant genomes.

The genome sequence of the filamentous fungus Neurospora crassa

Neurospora crassa is a central organism in the history of twentieth-century genetics, biochemistry and molecular biology. Here, we report a high-quality draft sequence of the N. crassa genome. The approximately 40-megabase genome encodes about 10,000 protein-coding genes--more than twice as many as in the fission yeast Schizosaccharomyces pombe and only about 25% fewer than in the fruitfly Drosophila melanogaster. Analysis of the gene set yields insights into unexpected aspects of Neurospora biology including the identification of genes potentially associated with red light photobiology, genes implicated in secondary metabolism, and important differences in Ca2+ signalling as compared with plants and animals. Neurospora possesses the widest array of genome defence mechanisms known for any eukaryotic organism, including a process unique to fungi called repeat-induced point mutation (RIP). Genome analysis suggests that RIP has had a profound impact on genome evolution, greatly slowing the creation of new genes through genomic duplication and resulting in a genome with an unusually low proportion of closely related genes.

Sputnik: a database platform for comparative plant genomics

Two million plant ESTs, from 20 different plant species, and totalling more than one 1000 Mbp of DNA sequence, represents a formidable transcriptomic resource. Sputnik uses the potential of this sequence resource to fill some of the information gap in the un-sequenced plant genomes and to serve as the foundation for in silicio comparative plant genomics. The complexity of the individual EST collections has been reduced using optimised EST clustering techniques. Annotation of cluster sequences is performed by exploiting and transferring information from the comprehensive knowledgebase already produced for the completed model plant genome (Arabidopsis thaliana) and by performing additional state of-the-art sequence analyses relevant to today's plant biologist. Functional predictions, comparative analyses and associative annotations for 500 000 plant EST derived peptides make Sputnik (http://mips.gsf.de/proj/sputnik/) a valid platform for contemporary plant genomics.

MIPS Arabidopsis thaliana Database (MAtDB): an integrated biological knowledge resource based on the first complete plant genome

Arabidopsis thaliana is the first plant for which the complete genome has been sequenced and published. Annotation of complex eukaryotic genomes requires more than the assignment of genetic elements to the sequence. Besides completing the list of genes, we need to discover their cellular roles, their regulation and their interactions in order to understand the workings of the whole plant. The MIPS Arabidopsis thaliana Database (MAtDB; http://mips.gsf.de/proj/thal/db) started out as a repository for genome sequence data in the European Scientists Sequencing Arabidopsis (ESSA) project and the Arabidopsis Genome Initiative. Our aim is to transform MAtDB into an integrated biological knowledge resource by integrating diverse data, tools, query and visualization capabilities and by creating a comprehensive resource for Arabidopsis as a reference model for other species, including crop plants.