Arabidopsis Retinoblastoma-related and Polycomb group proteins: cooperation during plant cell differentiation and development

Retinoblastoma-related (RBR) is the plant homologue of pRb, a tumour suppressor. This review discusses the molecular functions of RBR during plant development and in the control of the cell cycle, with emphasizing on its cooperation with chromatin-modifying factor

Arabidopsis thaliana proteomics: from proteome to genome

Proteomics has become an important approach for investigating cellular processes and network functions. Significant improvements have been made during the last few years in technologies for high-throughput proteomics, both at the level of data analysis software and mass spectrometry hardware. As proteomics technologies advance and become more widely accessible, efforts of cataloguing and quantifying full proteomes are underway to complement other genomics approaches, such as RNA and metabolite profiling. Of particular interest is the application of proteome data to improve genome annotation and to include information on post-translational protein modifications with the annotation of the corresponding gene. This type of analysis requires a paradigm shift because amino acid sequences must be assigned to peptides without relying on existing protein databases. In this review, advances and current limitations of full proteome analysis are briefly highlighted using the model plant Arabidopsis thaliana as an example. Strategies to identify peptides are also discussed on the basis of MS/MS data in a protein database-independent approac

Altered expression of the Arabidopsis ortholog of DCL affects normal plant development

The DCL (defective chloroplasts and leaves) gene of tomato (Lycopersicon esculentum Mill.) is required for chloroplast development, palisade cell morphogenesis, and embryogenesis. Previous work suggested that DCL protein is involved in 4.5S rRNA processing. The Arabidopsis thaliana (L.) Heynh. genome contains five sequences encoding for DCL-related proteins. In this paper, we investigate the function of AtDCL protein, which shows the highest amino acid sequence similarity with tomato DCL. AtDCL mRNA was expressed in all tissues examined and a fusion between AtDCL and green fluorescent protein (GFP) was sufficient to target GFP to plastids in vivo, consistent with the localization of AtDCL to chloroplasts. In an effort to clarify the function of AtDCL, transgenic plants with altered expression of this gene were constructed. Deregulation of AtDCL gene expression caused multiple phenotypes such as chlorosis, sterile flowers and abnormal cotyledon development, suggesting that this gene is required in different organs. The processing of the 4.5S rRNA was significantly altered in these transgenic plants, indicating that AtDCL is involved in plastid rRNA maturation. These results suggest that AtDCL is the Arabidopsis ortholog of tomato DCL, and indicate that plastid function is required for normal plant developmen

Control of trichome branching by Chromatin Assembly Factor-1

<p>Abstract</p> <p>Background</p> <p>Chromatin dynamics and stability are both required to control normal development of multicellular organisms. Chromatin assembly factor CAF-1 is a histone chaperone that facilitates chromatin formation and the maintenance of specific chromatin states. In plants and animals CAF-1 is essential for normal development, but it is poorly understood which developmental pathways require CAF-1 function.</p> <p>Results</p> <p>Mutations in all three CAF-1 subunits affect Arabidopsis trichome morphology and lack of CAF-1 function results in formation of trichomes with supernumerary branches. This phenotype can be partially alleviated by external sucrose. In contrast, other aspects of the CAF-1 mutant phenotype, such as defective meristem function and organ formation, are aggravated by external sucrose. Double mutant analyses revealed epistatic interactions between CAF-1 mutants and <it>stichel</it>, but non-epistatic interactions between CAF-1 mutants and <it>glabra3 </it>and <it>kaktus</it>. In addition, mutations in CAF-1 could partly suppress the strong overbranching and polyploidization phenotype of <it>kaktus </it>mutants.</p> <p>Conclusion</p> <p>CAF-1 is required for cell differentiation and regulates trichome development together with STICHEL in an endoreduplication-independent pathway. This function of CAF-1 can be partially substituted by application of exogenous sucrose. Finally, CAF-1 is also needed for the high degree of endoreduplication in <it>kaktus </it>mutants and thus for the realization of <it>kaktus</it>' extreme overbranching phenotype.</p

The molecular basis of human retinal and vitreoretinal diseases

During the last two to three decades, a large body of work has revealed the molecular basis of many human disorders, including retinal and vitreoretinal degenerations and dysfunctions. Although belonging to the group of orphan diseases, they affect probably more than two million people worldwide. Most excitingly, treatment of a particular form of congenital retinal degeneration is now possible. A major advantage for treatment is the unique structure and accessibility of the eye and its different components, including the vitreous and retina. Knowledge of the many different eye diseases affecting retinal structure and function (night and color blindness, retinitis pigmentosa, cone and cone rod dystrophies, photoreceptor dysfunctions, as well as vitreoretinal traits) is critical for future therapeutic development. We have attempted to present a comprehensive picture of these disorders, including clinical, genetic and molecular information. The structural organization of the review leads the reader through non-syndromic and syndromic forms of (i) rod dominated diseases, (ii) cone dominated diseases, (iii) generalized retinal degenerations and (iv) vitreoretinal disorders, caused by mutations in more than 165 genes. Clinical variability and genetic heterogeneity have an important impact on genetic testing and counselling of affected families. As phenotypes do not always correlate with the respective genotypes, it is of utmost importance that clinicians, geneticists, counsellors, diagnostic laboratories and basic researchers understand the relationships between phenotypic manifestations and specific genes, as well as mutations and pathophysiologic mechanisms. We discuss future perspectives

Virale und nichtvirale Gentherapieansätze zur Behandlung von Netzhauterkrankungen

Zusammenfassung: Für die Behandlung von Netzhauterkrankungen eröffnet der Einsatz der Gentherapie neue Perspektiven. Die Verwendung von verschiedenartigen Oligonukleotiden oder viralen Expressionsvektoren erlaubt die Entwicklung von neuen Heilungsstrategien für Neovaskularisierungskrankheiten und retinale Degeneration. Therapeutische Oligonukleotide ("Antisense"-Oligonukleotide, Aptamere und siRNA) können den gezielten Abbau von Transkripten und damit die Konzentrationsabnahme eines an der Pathogenese beteiligten Proteins induzieren. Dagegen wird mit viralen Vektoren (rAAV und Lentivirus) häufig die Funktion eines defekten Gens durch die eines gesunden ersetzt und so die Ursache der Krankheit bekämpft. Die an Tiermodellen erfolgreich angewandten Gentherapien führten bereits zur Entwicklung von Medikamenten, und weitere werden zurzeit klinisch erprob

pep2pro: the high-throughput proteomics data processing, analysis, and visualization tool

The pep2pro database was built to support effective high-throughput proteome data analysis. Its database schema allows the coherent integration of search results from different database-dependent search algorithms and filtering of the data including control for unambiguous assignment of peptides to proteins. The capacity of the pep2pro database has been exploited in data analysis of various Arabidopsis proteome datasets. The diversity of the datasets and the associated scientific questions required thorough querying of the data. This was supported by the relational format structure of the data that links all information on the sample, spectrum, search database, and algorithm to peptide and protein identifications and their post-translational modifications. After publication of datasets they are made available on the pep2pro website at www.pep2pro.ethz.ch. Further, the pep2pro data analysis pipeline also handles data export do the PRIDE database (http://www.ebi.ac.uk/pride) and data retrieval by the MASCP Gator (http://gator.masc-proteomics.org/). The utility of pep2pro will continue to be used for analysis of additional datasets and as a data warehouse. The capacity of the pep2pro database for proteome data analysis has now also been made publicly available through the release of pep2pro4all, which consists of a database schema and a script that will populate the database with mass spectrometry data provided in mzIdentML format

Dose-dependent RNAi-mediated geminivirus resistance in the tropical root crop cassava

Cassava mosaic disease is a major constraint for cassava production in Africa, resulting in significant economic losses. We have engineered transgenic cassava with resistance to African cassava mosaic virus (ACMV), by expressing ACMV AC1-homologous hairpin double-strand RNAs. Transgenic cassava lines with high levels of AC1-homologous small RNAs have ACMV immunity with increasing viral load and different inoculation methods. We report a correlation between the expression of the AC1-homologous small RNAs and the ACMV resistance of the transgenic cassava lines. Characterization of the small RNAs revealed that only some of the hairpin-derived small RNAs fall into currently known small interfering RNA classes in plants. The method is scalable to stacking by targeting multiple virus isolates with additional hairpin

Biofortification of essential nutritional compounds and trace elements in rice and cassava

Plant biotechnology can make important contributions to food security and nutritional improvement. For example, the development of ‘Golden Rice' by Professor Ingo Potrykus was a milestone in the application of gene technology to deliver both increased nutritional qualities and health improvement to wide sections of the human population. Mineral nutrient and protein deficiency as well as food security remain the most important challenges for developing countries. Current projects are addressing these issues in two major staple crops, cassava (Manihot esculenta Crantz) and rice. The tropical root crop cassava is a major source of food for approximately 600 million of the population worldwide. In sub-Saharan Africa >200 million of the population rely on cassava as their major source of dietary energy. The nutritional quality of the cassava root is not sufficient to meet all dietary needs. Rice is the staple food for half the world population, providing approximately 20% of the per capita energy and 13% of the protein for human consumption worldwide. In many developing countries the dietary contributions of rice are substantially greater (29·3% dietary energy and 29·1% dietary protein). The current six most popular ‘mega' rice varieties (in terms of popularity and acreage), including Chinese hybrid rice, have an incomplete amino acid profile and contain limited amounts of essential micronutrients. Rice lines with improved Fe contents have been developed using genes that have functions in Fe absorption, translocation and accumulation in the plant, as well as improved Fe bioavailability in the human intestine. Current developments in biotechnology-assisted plant improvement are reviewed and the potential of the technology in addressing human nutrition and health are discusse

Arabidopsis transcript profiling on Affymetrix GeneChip arrays

DNA microarrays are becoming a frequently used research tool. Whilst several studies have confirmed the reproducibility of analysing the same RNA samples on duplicate arrays, there is little analysis of the reproducibility of the results of transcript profiling between microarrays carrying different probes to a common set of genes. To address this question, we compared the performance and reproducibility of two microarrays commonly used in plant research, the Affymetrix Arabidopsis AG array containing more than 8000 probe sets and the Affymetrix Arabidopsis ATH1 array containing more than 22 000 redesigned probe sets. A total of 21 different RNA samples were labelled and hybridized in parallel to the two microarray types. Focusing on the overlap of more than 7300 targets detected with both arrays, we found a high degree of reproducibility. Despite the use of different probe sets, both signal and signal log ratio were very similar for most genes. However, genes that were called absent or not changed by Affymetrix' statistical algorithm implemented in MAS5.0 showed considerably less conservation of expression patterns. Moreover, we identified about 300 genes that yielded strongly different measurements with the two microarrays, emphasizing that RNA profiling data need careful interpretation. Overall, this study shows that results obtained with ATH1 and AG arrays are very comparable and hence that the analysis is largely independent of probe sets. However, the result emphasize the need for appropriate filtering schemes such as those based on the present and change calls provided by MAS5.0 rather than reliance solely on signal value