https://pure.mpg.de/pubman/item/item_641885_3/component/file_641884/124826.pdf

The small RNA profile during Drosophila melanogaster development

Homology-dependent Gene Silencing in Plants.

The FT37/1 tumor line induced by Agrobacterium tumefaciens on flax epicotyls contains 22-24 copies of the T-DNA encoded nopaline synthase gene per cell. All the gene copies are methylated to some extent but the methylation is not uniform, nor does it reflect the methylation level of the flanking plant DNA. This extensive methylation correlates with an extremely low level of expression of the nopaline synthase gene. Treatment of the tumor line with the in vivo demethylating drug 5-azacytidine at a concentration of 3 X 10(-5) M, resulted in the demethylation of, on average, one copy of the nopaline synthase gene per cell. This demethylation was paralleled by an increase in the transcription of the gene and indicates that cytosine methylation is capable of suppressing the expression of plant genes in vivo.

The role of cytosine methylation in the control of nopaline synthase gene expression in a plant tumor [Agrobacterium tumefaciens]

Polyploid organisms contain a number of chromosomes that is some multiple of x (basic chromosome number) greater than the 2 x content of related diploid species. [Winkler (1916)][1] introduced the term in a study of vegetative grafts in Solanum, when he discovered tetraploid plants regenerated from

A sense of self: the role of DNA sequence elimination in allopolyploidization.

On entering a host cell, positive-strand RNA virus genomes have to serve as messenger for the translation of viral proteins. Efficient translation of cellular messengers requires interactions between initiation factors bound to the 5′-cap structure and the poly(A) binding protein bound to the 3′-poly(A) tail. Initiation of infection with the tripartite RNA genomes of alfalfa mosaic virus (AMV) and viruses from the genus Ilarvirus requires binding of a few molecules of coat protein (CP) to the 3′ end of the nonpolyadenylated viral RNAs. Moreover, infection with the genomic RNAs can be initiated by addition of the subgenomic messenger for CP, RNA 4. We report here that extension of the AMV RNAs with a poly(A) tail of 40 to 80 A-residues permitted initiation of infection independently of CP or RNA 4 in the inoculum. Specifically, polyadenylation of RNA 1 relieved an apparent bottleneck in the translation of the viral RNAs. Translation of RNA 4 in plant protoplasts was autocatalytically stimulated by its encoded CP. Mutations that interfered with CP binding to the 3′ end of viral RNAs reduced translation of RNA 4 to undetectable levels. Possibly, CP of AMV and ilarviruses stimulates translation of viral RNAs by acting as a functional analogue of poly(A) binding protein or other cellular proteins.

https://www.pnas.org/content/pnas/98/25/14286.full.pdf

Translation of a nonpolyadenylated viral RNA is enhanced by binding of viral coat protein or polyadenylation of the RNA.

The definition of a disease is fundamentally difficult, even if one considers only genetically based diseases. In its broadest sense, disease can be defined as any deviation from the norm that results in a physiological disadvantage. Natural selection ensures that the norm for any given species is constantly changing. In addition, some disadvantages are latent and might only manifest under certain environmental conditions. Conversely, an apparent disadvantage can carry a benefit, for example, the disease sickle-cell anemia that is an advantage in malarial areas. Because of the difficulties in giving disease a precise definition, in this review, gene silencing-based disease resistance will be restricted to the description of gene inactivation processes that contribute to maintain the physical fitness of an organism. In this sense, we are concerned with the elimination of invasive nucleic acid expressing. In numerous organisms, a variety of severe diseases are caused by the attack of invasive nucleic acids such as viruses and retroviral or transposable elements. Organisms have developed diverse mechanisms to defend themselves against such attack that include immune responses and apoptosis. Fungi, plants, invertebrates and vertebrates also enlist gene silencing systems to counteract the harmful effects of invasive nucleic acids. In particular, plants that lack interferon and immune responses have established efficient transcriptional and post-transcriptional gene silencing systems. In this review, we describe how plants defend against invasive nucleic acids and focus on the continual evolutionary battle between plants and viruses. In addition, the importance of controlling transposon activity is outlined. Finally, gene silencing-related mechanisms of genomic imprinting and X-chromosome inactivation are discussed in the context of disease resistance.

Gene silencing-based disease resistance.

Plants have evolved a plethora of mechanisms to respond to the environment and modulate growth and reproduction. Abiotic signals provided by light, temperature and the availability of water, oxygen and nutrients are controlling factors. Many species possess strategies to endure abiotic assaults, and to respond to challenges from bacterial, fungal and viral pathogens. Although these responses are frequently regulated at the transcriptional level, there is extraordinary diversity in the post‐transcriptional mechanisms that promote developmental plasticity and adaptation. The phenomenon of silencing of heterologous genes also involves transcriptional and post‐transcriptional mechanisms. Current research links gene silencing to ordinary post‐transcriptional mechanisms as well as defense of viral RNAs. An EMBO Workshop in Leysin, Switzerland, explored the mechanisms, implications and connections of post‐transcriptional processes in plants. Several non‐plant scientists also participated and presented an overview of post‐transcriptional processes in mammals and yeast.

Confocal microscopy and in situ hybridization procedures have led to enormous progress in the visualization of the spatial organization and dynamics of transcription and RNA‐processing machinery in eukaryotic cells. It is well established that the nucleus is a highly organized structure composed of many different territories, subdomains and organelles (Lamond and Earnshaw, 1998). A state‐of‐the‐art account of the nuclear architecture of plant cells was given by P.Shaw (John Innes Centre, Norwich, UK). Mapping of the RNA polymerase I transcription and rRNA processing sites, using different pre‐rRNA, snoRNA and nucleolar protein probes, indicates that the plant cell nucleolus is organized as a series of concentric layers in which transcription and successive rRNA processing reactions occur. As in vertebrate cells, plant cells contain coiled bodies (CBs), nuclear organelles of still poorly defined function. Since CB components include several small RNAs, and also proteins related to either their assembly or function, CBs are thought to be involved in snRNP/snoRNP maturation, recycling or transport. Stably …

/pdf/plants-their-organelles-viruses-and-transgenes-reveal-the-2bes3vk6wt.pdf

Plants, their organelles, viruses and transgenes reveal the mechanisms and relevance of post-transcriptional processes. Leysin, VD, Switzerland, February 25-28, 1999.

The expression of a gene is a fundamental biological process with both immediate effects on an individual organism as well as long-term consequences for the evolution of the living world. As such, gene expression is regulated by elaborate control mechanisms that act or interact to ensure a fine context-specific tuning. Transgenes are subject to the same range of gene regulatory mechanisms that control endogenes. In addition, transgenes, like other newly acquired foreign or ‘invasive’ DNA elements in the genome, appear particularly susceptible to control mechanisms that detect and act upon ‘abnormalities’ encoded by the transgene sequence or structure, the transgene's positional and compositional relation to its genomic environment, the transgene's expression pattern, and the intrinsic and extrinsic characteristics of transgenic RNA intermediates and gene products. A thorough understanding of the pathway of gene expression, from transcriptional regulation by genetic and epigenetic mechanisms, through to RNA and protein degradation, and the targets this pathway provides for gene regulatory processes to intervene, is essential for the successful application of transgenic tools in today's plant biotechnology.


Keywords:

epigenetic;
transcription;
post-transcription;
gene silencing

Control and Silencing of Transgene Expression

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Michael Wassenegger

Author Tools

Chat about Author

Papers

Gene silencing-based disease resistance.

Plants, their organelles, viruses and transgenes reveal the mechanisms and relevance of post-transcriptional processes. Leysin, VD, Switzerland, February 25-28, 1999.

Control and Silencing of Transgene Expression