This document summarizes gene silencing mechanisms including transcriptional gene silencing (TGS) and post-transcriptional gene silencing (PTGS). TGS involves modifications of histones or DNA that alter accessibility of genes to transcriptional machinery. PTGS results from mRNA of a gene being destroyed or blocked, such as via RNA interference (RNAi). RNAi was discovered in C. elegans and involves long dsRNA being processed by the Dicer enzyme into siRNAs that guide an RISC complex to degrade complementary mRNAs. MicroRNAs also guide RISC complexes but typically block translation rather than degradation.
RNAi is a powerful, conserved biological process through which the small, double-stranded RNAs specifically silence the expression of homologous genes, largely through degradation of their cognate mRNA.
RNA interference (RNAi) is a mechanism that inhibits gene expression at the stage of translation or by hindering the transcription of specific genes.
RNAi targets include RNA from viruses and transposons.
RNA interference (RNAi): Cellular process by which an mRNA is targeted for degradation by a dsRNA with a strand complementary to a fragment of such mRNA.
RNAi is a powerful, conserved biological process through which the small, double-stranded RNAs specifically silence the expression of homologous genes, largely through degradation of their cognate mRNA.
RNA interference (RNAi) is a mechanism that inhibits gene expression at the stage of translation or by hindering the transcription of specific genes.
RNAi targets include RNA from viruses and transposons.
RNA interference (RNAi): Cellular process by which an mRNA is targeted for degradation by a dsRNA with a strand complementary to a fragment of such mRNA.
RNA interference (RNAi) is a biological process in which RNA molecules inhibit gene expression, typically by causing the destruction of specific mRNA molecules. Historically, it was known by other names, including co-suppression, post-transcriptional gene silencing (PTGS), and quelling.
An introduction to RNAi technology - Petr Svoboda - Institute of Molecular Ge...OECD Environment
10-12 April 2019: The OECD Conference on RNAi based pesticides provided an overview on the current status and future possibilities for the regulation of externally applied dsRNA-based products that are proposed for use as pesticides. The event facilitated exchanges between policy makers, academia, industry on their implications in health, environment, and regulation.
Transcriptomics is the study of RNA, single-stranded nucleic acid, which was not separated from the DNA world until the central dogma was formulated by Francis Crick in 1958, i.e., the idea that genetic information is transcribed from DNA to RNA and then translated from RNA into protein.
RNA Interference(RNAi) is a conserved biological response of eukaryotes against double-stranded RNA causing silencing of the gene expression. This mechanism has an important role in defending cells against viral genes and transposons. RNAi technology has become the latest "next big thing," progressing from a barely understood colour silencing mechanism found in flowers to a powerful tool that is going to become a new therapeutic tool for treating illnesses ranging from AIDS to cancer to Huntington’s disease. Even more exciting is the potential of RNAi in agriculture where it has provided a way to control pests and diseases as well as increase nutritional value of food.
RNA interference (RNAi) is a biological process in which RNA molecules inhibit gene expression, typically by causing the destruction of specific mRNA molecules. Historically, it was known by other names, including co-suppression, post-transcriptional gene silencing (PTGS), and quelling.
An introduction to RNAi technology - Petr Svoboda - Institute of Molecular Ge...OECD Environment
10-12 April 2019: The OECD Conference on RNAi based pesticides provided an overview on the current status and future possibilities for the regulation of externally applied dsRNA-based products that are proposed for use as pesticides. The event facilitated exchanges between policy makers, academia, industry on their implications in health, environment, and regulation.
Transcriptomics is the study of RNA, single-stranded nucleic acid, which was not separated from the DNA world until the central dogma was formulated by Francis Crick in 1958, i.e., the idea that genetic information is transcribed from DNA to RNA and then translated from RNA into protein.
RNA Interference(RNAi) is a conserved biological response of eukaryotes against double-stranded RNA causing silencing of the gene expression. This mechanism has an important role in defending cells against viral genes and transposons. RNAi technology has become the latest "next big thing," progressing from a barely understood colour silencing mechanism found in flowers to a powerful tool that is going to become a new therapeutic tool for treating illnesses ranging from AIDS to cancer to Huntington’s disease. Even more exciting is the potential of RNAi in agriculture where it has provided a way to control pests and diseases as well as increase nutritional value of food.
Antisense RNA Technology for crop improvement.pptxSanyamPatel2
Improvement of crops by following genetic engineering techniques:
Gene silencing
Post transcription silencing
Post translation silencing
Antisense RNA
RNA interference
5. How do splicing and the RNAi mechanism regulate which mRNA molecu.pdfmallik3000
5. How do splicing and the RNAi mechanism regulate which mRNA molecules are translated?
Which small RNA molecules are required for each process?
Solution
The splicing and the RNAi mechanism (microRNA & small interfering RNA (siRNA)) regulate
which mRNA molecules are translated as siRNA or snRNA is also known as U-RNA as it
contains many uridine contents in its complex structure. This is composed of 150 nucleotides
nearly to produce spliceosomes and to act along with snRNP. This snRNA has a predominant
role in splicing.
The RNA-induced initiation of transcription silencing complex (RITC): Inside the nucleus,
genomic DNA is going to identify initially by this complex using single stranded RNA or
microRNAs associated with recruiting chromatin remodeling protein for the silencing initiation
and transcription repression.
MicroRNA\'s (miRNA) are the small non-coding products of gene of 21 to 27 nucleotides length.
These miRNAs cause gene silencing by the inactivation of mRNA and thus, regulates gene
expression (post-transcriptional gene regulation by binding to 3\'- UTR region of target mRNA).
Micro RNA\'s are known to attack genes by inhibiting the translation from taking place. One
miRNA can silence many mRNAs because the 3\'-UTRs (untranslated regions) of mRNAs have
some common seed sequences to which these miRNAs can bind and trigger gene silencing.
MiRNA and SiRNAs are regulatory RNA which can silence the mRNA either by cleavage or by
base pairing to the mRNA thus “regulates transcription” & translation. Sometimes these RNAs
can regulate post-transcritional activity of mRNA
Small interfering RNA (siRNA) and micro RNA have both can silence gene expression of other
foreign genes
Small interfering RNA and micro RNA are double standard RNAs
Dicer: it is also referred as endoribonuclease Dicer. It has activity of cleaving double-stranded
RNA and pre –microRNA into specific fragments of RNA 20 to 15 kb (double stranded). This
enzyme is also known as helicase with RNase. This enzyme called dicer and large RNA
molecules produces small interfering RNA and micro RNA.
Gene expression & dicer: The process of generation of messenger RNA from genome of DNA in
the presence of RNA polymerase and transcription factors is known as “gene expression”. Dicer
influences gene expression by binding to “nascent mRNA” to cut into small fragments result in
negative feedback of gene expression
Diffrenece: siRNAs usually originates from mRNAs exerts perfect action on targets;
RITS binds with siRNA and causes RNA transcriptional silencing whereas RISC cleaves
mRNA. SWR1 –switch remodeling causes chromatin remodeling allows RNAase to enable
transcription with a variant H2AZ. Imitation switch complex
(ISWI) enable transcriptional silencing is by displacing nucleosome positions from open to
close.
For example,
In fission yeast, defective RNA interference (RNAi) is leading to loss of H3K9 methylation at
cetromere result in loss of centromere function. Through a series of trans.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Ethnobotany and Ethnopharmacology:
Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
Bio-prospecting tools for drug discovery,
Role of Ethnopharmacology in drug evaluation,
Reverse Pharmacology.
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
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2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Model Attribute Check Company Auto PropertyCeline George
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Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
The Indian economy is classified into different sectors to simplify the analysis and understanding of economic activities. For Class 10, it's essential to grasp the sectors of the Indian economy, understand their characteristics, and recognize their importance. This guide will provide detailed notes on the Sectors of the Indian Economy Class 10, using specific long-tail keywords to enhance comprehension.
For more information, visit-www.vavaclasses.com
Students, digital devices and success - Andreas Schleicher - 27 May 2024..pptxEduSkills OECD
Andreas Schleicher presents at the OECD webinar ‘Digital devices in schools: detrimental distraction or secret to success?’ on 27 May 2024. The presentation was based on findings from PISA 2022 results and the webinar helped launch the PISA in Focus ‘Managing screen time: How to protect and equip students against distraction’ https://www.oecd-ilibrary.org/education/managing-screen-time_7c225af4-en and the OECD Education Policy Perspective ‘Students, digital devices and success’ can be found here - https://oe.cd/il/5yV
35. Core components of the RNAi
pathway
• Dicer
Dicer family proteins contain an N-terminal helicase
domain, a C-terminal segment containing dual RNase III
domains, and one or more dsRNA-binding motifs. Family
members also contain a PAZ domain.
•Member of RNAseIII family of enzymes.
• Recognize and process dsRNA into siRNA.
• Dicer family proteins are ATP-dependent nucleases.
• Dicer homologs exist in many organisms
includingC.elegans, Drosophila, yeast and humans.
48. Two-step model for the mechanism of gene silencing induced by double-stranded RNA. In
step I, dsRNA is cleaved by the Dicer enzyme to produce siRNAs.
49. Two-step model for the mechanism of gene silencing induced by double-stranded RNA. In
step I, dsRNA is cleaved by the Dicer enzyme to produce siRNAs.
50. Two-step model for the mechanism of gene silencing induced by double-stranded RNA. In
step I, dsRNA is cleaved by the Dicer enzyme to produce siRNAs.
62. • miRNA Biogenesis
– Transcribed from endogenous gene as pri-miRNA
• Primary miRNA: long with multiple hairpins
• Imperfect internal sequence complementarity
– It is processed into 70-nt hairpins by the RNase III family
member Drosha to become the pre-miRNA.
• Note: How does it identify pri-miRNA?
– Hairpin terminal loop size
– Stem structure
– Hairpin flanking sequences
– The pre-miRNA is exported to the cytoplasm by Exportin 5.
– It is cleaved by the R2D2/Dicer heterodimer into the mature
miRNA.
• Symmetric 2nt 3’ overhangs, 5’ phosphate groups
63. DCL1 mutant
Comparison of Mechanisms of MiRNA Biogenesis and Action
Better complementarity of MiRNAs and targets in plants.
64. Summary of differences between plant and animal MiRNA
systems
Plants Animals
miRNA genes: 100-200 100-500
Location in genome: intergenic regions Intergenic regions, introns
Clusters of miRNAs: Uncommon Common
MiRNA biosynthesis: Dicer-like Drosha, Dicer
Mechanism of repression mRNA cleavage Translational repression
Location of miRNA
target in a gene: Predominantly Predominantly the 3′-UTR
the open-reading frame
miRNA binding
sites in a target gene: Generally one Generally multiple
Functions of known
target genes: Regulatory genes Regulatory genes—crucial
crucial for development, for development, structural
enzymes proteins, enzymes