This document discusses precipitation reactions which involve combining soluble antigen and antibody to form insoluble complexes. For precipitation to occur, the antigen and antibody must have multiple binding sites for each other and be present in equal concentrations. The affinity and avidity of the antibody also influence precipitation. Optimal precipitation happens in the zone of equivalence where the number of antigen and antibody binding sites are approximately equal. Precipitation can be measured using techniques like turbidimetry, nephelometry, and immunodiffusion in a gel matrix.
Direct
Passive
Reverse Passive
Agglutination Inhibition
Coagglutination
Agglutination tests can be done :
On slides
In tubes
In microtritation plates
-Difference between precipitation and agglutination reaction.
This is prepared for my project and im sharing this for useful to others.This slides contain the processing of urine specimens in microbiology.im prepared on basis of our medical college method.sometimes the methods will vary with other hospitals
Direct
Passive
Reverse Passive
Agglutination Inhibition
Coagglutination
Agglutination tests can be done :
On slides
In tubes
In microtritation plates
-Difference between precipitation and agglutination reaction.
This is prepared for my project and im sharing this for useful to others.This slides contain the processing of urine specimens in microbiology.im prepared on basis of our medical college method.sometimes the methods will vary with other hospitals
As the channel name suggests, our channel will be a perfect lounge for the malayali medicos..we wil be covering videos which will be like lecture classes related to the subjects biochemistry and microbiology in which we are specialised.. It will be a better learning experience for the students especially for those who are not able to understand and follow the normal classes in college..we assure the students that you will get a basic idea regarding the topic and extra reading can be done from the reference textbooks..
Qalification
AHLAD T O
MSc MLT (Biochemistry)
Assistant Professor
Baby memorial college of allied Health science
Kozhikode
Maneesha M Joseph
MSc MLT (Microbiology)
Assistant Professor
Baby memorial college of allied Health science
Kozhikode
Our Partner Channel
Health & Voyage channel link - https://youtu.be/nzKqRVjlwc0
#Proteus microbiology
#Medical
#Microbiology
#Biochemistry
#Mallu Medicos Lounge
##MalluMedicosLounge
#MLT
#Channel introduction
#HealthAndVoyage
#New Youtube Channel introduction
#Gram-negative
#Enterobactericea
#Weil Felix Test
#PROTEUS - causes, symptoms, diagnosis, treatment, pathology
For More Medicine Free PPT - http://playnever.blogspot.com/
For Health benefits and medicine videos Subscribe youtube channel - https://www.youtube.com/playlist?list=PLKg-H-sMh9G01zEg4YpndngXODW2bq92w
serology presentation
Serology is the scientific study of blood serum and other bodily fluids such as semen and saliva.
In practical immunological terms, serology is the diagnostic identification of antibodies in the serum.
Antibodies are typically formed in response to;
An infection, (against a given microorganism),
Other foreign proteins (blood transfusion)
Or to one’s own proteins (autoimmune disease).
TPHA is abbreviation of treponema pallidum hemagglutination assay to treponemal test for the serologic diagnosis of syphilis, a sexually transmitted infection caused by a Spirochetes, Treponema pallidum.
Based on the principle of passive haemagglutination, this test detects anti-treponemal antibodies (IgG and IgM antibodies) in serum or CSF.
TPHA is a good primary screening test for syphilis at all stages beyond the early primary stage.
Microbiology of E coli giving basic of Escherichia coli, its morphology, cultural and biochemical characteristics, Antigenic character, pathogenesis, laboratory diagnosis, prevention and control
The genus Shigella exclusively infects human intestine.
Shigella dysenteriae is the causative agent of bacillary dysentery or shigellosis in humans.
It is a diarrheal illness which is characterized by frequent passage of blood stained mucopurulent stools.
The four important species of the genus Shigella are:
Shigella dysenteriae
Shigella flexneri
Shigella sonnei
Shigella boydii.
As the channel name suggests, our channel will be a perfect lounge for the malayali medicos..we wil be covering videos which will be like lecture classes related to the subjects biochemistry and microbiology in which we are specialised.. It will be a better learning experience for the students especially for those who are not able to understand and follow the normal classes in college..we assure the students that you will get a basic idea regarding the topic and extra reading can be done from the reference textbooks..
Qalification
AHLAD T O
MSc MLT (Biochemistry)
Assistant Professor
Baby memorial college of allied Health science
Kozhikode
Maneesha M Joseph
MSc MLT (Microbiology)
Assistant Professor
Baby memorial college of allied Health science
Kozhikode
Our Partner Channel
Health & Voyage channel link - https://youtu.be/nzKqRVjlwc0
#Proteus microbiology
#Medical
#Microbiology
#Biochemistry
#Mallu Medicos Lounge
##MalluMedicosLounge
#MLT
#Channel introduction
#HealthAndVoyage
#New Youtube Channel introduction
#Gram-negative
#Enterobactericea
#Weil Felix Test
#PROTEUS - causes, symptoms, diagnosis, treatment, pathology
For More Medicine Free PPT - http://playnever.blogspot.com/
For Health benefits and medicine videos Subscribe youtube channel - https://www.youtube.com/playlist?list=PLKg-H-sMh9G01zEg4YpndngXODW2bq92w
serology presentation
Serology is the scientific study of blood serum and other bodily fluids such as semen and saliva.
In practical immunological terms, serology is the diagnostic identification of antibodies in the serum.
Antibodies are typically formed in response to;
An infection, (against a given microorganism),
Other foreign proteins (blood transfusion)
Or to one’s own proteins (autoimmune disease).
TPHA is abbreviation of treponema pallidum hemagglutination assay to treponemal test for the serologic diagnosis of syphilis, a sexually transmitted infection caused by a Spirochetes, Treponema pallidum.
Based on the principle of passive haemagglutination, this test detects anti-treponemal antibodies (IgG and IgM antibodies) in serum or CSF.
TPHA is a good primary screening test for syphilis at all stages beyond the early primary stage.
Microbiology of E coli giving basic of Escherichia coli, its morphology, cultural and biochemical characteristics, Antigenic character, pathogenesis, laboratory diagnosis, prevention and control
The genus Shigella exclusively infects human intestine.
Shigella dysenteriae is the causative agent of bacillary dysentery or shigellosis in humans.
It is a diarrheal illness which is characterized by frequent passage of blood stained mucopurulent stools.
The four important species of the genus Shigella are:
Shigella dysenteriae
Shigella flexneri
Shigella sonnei
Shigella boydii.
Preanalytical variables in coagulation testingShabab Ali
Coagulation: In medicine, the clotting of blood. The process by which the blood clots to form solid masses, or clots.
More than 30 types of cells and substances in blood affect clotting. The process is initiated by blood platelets. Platelets produce a substance that combines with calcium ions in the blood to form thromboplastin, which in turn converts the protein prothrombin into thrombin in a complex series of reactions. Thrombin, a proteolytic enzyme, converts fibrinogen, a protein substance, into fibrin, an insoluble protein that forms an intricate network of minute threadlike structures called fibrils and causes the blood plasma to gel. The blood cells and plasma are enmeshed in the network of fibrils to form the clot.
Coagulation: In medicine, the clotting of blood. The process by which the blood clots to form solid masses, or clots.
More than 30 types of cells and substances in blood affect clotting. The process is initiated by blood platelets. Platelets produce a substance that combines with calcium ions in the blood to form thromboplastin, which in turn converts the protein prothrombin into thrombin in a complex series of reactions. Thrombin, a proteolytic enzyme, converts fibrinogen, a protein substance, into fibrin, an insoluble protein that forms an intricate network of minute threadlike structures called fibrils and causes the blood plasma to gel. The blood cells and plasma are enmeshed in the network of fibrils to form the clot.
serological techniques for detection of plant virus.pptxReddykumarAv
Serological tests involve diagnostic procedures for identifying antibodies and antigens in a patient's blood sample. Serology definition tells that Serological tests could be used to diagnose infections and autoimmune disorders, as well as to see whether a person is resistant to these kinds of diseases and for a variety of other purposes, including assessing a person's blood type.
Antigen-antibody interaction, or antigen-antibody reaction, is a specific chemical interaction between antibodies produced by B cells of the white blood cells and antigens during immune reaction. It is the fundamental reaction in the body by which the body is protected from complex foreign molecules, such as pathogens and their chemical toxins. In the blood, the antigens are specifically and with high affinity bound by antibodies to form an antigen-antibody complex. The immune complex is then transported to cellular systems where it can be destroyed or deactivated.
Antigen-Antibody Interactions -
Antigen-antibody interactions depend on four types
of noncovalent interactions: hydrogen bonds, ionic
bonds, hydrophobic interactions, and van der Waals
interactions.
The affinity constant, which can be determined by
Scatchard analysis, provides a quantitative measure of the
strength of the interaction between an epitope of the antigen
and a single binding site of an antibody. The avidity reflects
the overall strength of the interactions between a
multivalent antibody molecule and a multivalent antigen
molecule at multiple sites.
The interaction of a soluble antigen and precipitating antibody
in a liquid or gel medium forms an Ag-Ab precipitate.
Electrophoresis can be combined with precipitation
in gels in a technique called immunoelectrophoresis.
The interaction between a particulate antigen and agglutinating
antibody (agglutinin) produces visible clumping, or
agglutination that forms the basis of simple, rapid, and
sensitive immunoassays.
Radioimmunoassay (RIA) is a highly sensitive and quantitative
procedure that utilizes radioactively labeled antigen
or antibody.
The enzyme-linked immunosorbent assay (ELISA) depends
on an enzyme-substrate reaction that generates a
colored reaction product. ELISA assays that employ
chemiluminescence instead of a chromogenic reaction are
the most sensitive immunoassays available.
In Western blotting, a protein mixture is separated by electrophoresis;
then the protein bands are electrophoretically
transferred onto nitrocellulose and identified with labeled
antibody or labeled antigen.
Fluorescence microscopy using antibodies labeled with
fluorescent molecules can be used to visualize antigen on
or within cells.
Flow cytometry provides an unusually powerful technology
for the quantitative analysis and sorting of cell populations
labeled with one or more fluorescent antibodies.
Radioimmunoassay is the technique in which radioisotopes is used as a tag or label radioisotopes is covalently linked with Ag & Ab for the detection of ( Ag & Abs) complex
Immunodiffusion -Different Types,Principle,procedureand application. it is a diagnostic technique for the detection or measurements of antibodies and antigens by their precipitation which involves diffusion through a substances such as agar or gel agarose .common types -oudin procedure,oakley fulthorpe procedure ,mancini technique ,ouchterlony double immuno diffusion
over view of common antigen antibody reactions, their applications, sensitivity, advantage and disadvantage with pictorial illustrations for postgraduate and undergraduate reading
Coagulation: In medicine, the clotting of blood. The process by which the blood clots to form solid masses, or clots.
More than 30 types of cells and substances in blood affect clotting. The process is initiated by blood platelets. Platelets produce a substance that combines with calcium ions in the blood to form thromboplastin, which in turn converts the protein prothrombin into thrombin in a complex series of reactions. Thrombin, a proteolytic enzyme, converts fibrinogen, a protein substance, into fibrin, an insoluble protein that forms an intricate network of minute threadlike structures called fibrils and causes the blood plasma to gel. The blood cells and plasma are enmeshed in the network of fibrils to form the clot.
Coagulation: In medicine, the clotting of blood. The process by which the blood clots to form solid masses, or clots.
More than 30 types of cells and substances in blood affect clotting. The process is initiated by blood platelets. Platelets produce a substance that combines with calcium ions in the blood to form thromboplastin, which in turn converts the protein prothrombin into thrombin in a complex series of reactions. Thrombin, a proteolytic enzyme, converts fibrinogen, a protein substance, into fibrin, an insoluble protein that forms an intricate network of minute threadlike structures called fibrils and causes the blood plasma to gel. The blood cells and plasma are enmeshed in the network of fibrils to form the clot.
Coagulation: In medicine, the clotting of blood. The process by which the blood clots to form solid masses, or clots.
More than 30 types of cells and substances in blood affect clotting. The process is initiated by blood platelets. Platelets produce a substance that combines with calcium ions in the blood to form thromboplastin, which in turn converts the protein prothrombin into thrombin in a complex series of reactions. Thrombin, a proteolytic enzyme, converts fibrinogen, a protein substance, into fibrin, an insoluble protein that forms an intricate network of minute threadlike structures called fibrils and causes the blood plasma to gel. The blood cells and plasma are enmeshed in the network of fibrils to form the clot.
Coagulation: In medicine, the clotting of blood. The process by which the blood clots to form solid masses, or clots.
More than 30 types of cells and substances in blood affect clotting. The process is initiated by blood platelets. Platelets produce a substance that combines with calcium ions in the blood to form thromboplastin, which in turn converts the protein prothrombin into thrombin in a complex series of reactions. Thrombin, a proteolytic enzyme, converts fibrinogen, a protein substance, into fibrin, an insoluble protein that forms an intricate network of minute threadlike structures called fibrils and causes the blood plasma to gel. The blood cells and plasma are enmeshed in the network of fibrils to form the clot.
Coagulation: In medicine, the clotting of blood. The process by which the blood clots to form solid masses, or clots.
More than 30 types of cells and substances in blood affect clotting. The process is initiated by blood platelets. Platelets produce a substance that combines with calcium ions in the blood to form thromboplastin, which in turn converts the protein prothrombin into thrombin in a complex series of reactions. Thrombin, a proteolytic enzyme, converts fibrinogen, a protein substance, into fibrin, an insoluble protein that forms an intricate network of minute threadlike structures called fibrils and causes the blood plasma to gel. The blood cells and plasma are enmeshed in the network of fibrils to form the clot.
Coagulation: In medicine, the clotting of blood. The process by which the blood clots to form solid masses, or clots.
More than 30 types of cells and substances in blood affect clotting. The process is initiated by blood platelets. Platelets produce a substance that combines with calcium ions in the blood to form thromboplastin, which in turn converts the protein prothrombin into thrombin in a complex series of reactions. Thrombin, a proteolytic enzyme, converts fibrinogen, a protein substance, into fibrin, an insoluble protein that forms an intricate network of minute threadlike structures called fibrils and causes the blood plasma to gel. The blood cells and plasma are enmeshed in the network of fibrils to form the clot.
Coagulation: In medicine, the clotting of blood. The process by which the blood clots to form solid masses, or clots.
More than 30 types of cells and substances in blood affect clotting. The process is initiated by blood platelets. Platelets produce a substance that combines with calcium ions in the blood to form thromboplastin, which in turn converts the protein prothrombin into thrombin in a complex series of reactions. Thrombin, a proteolytic enzyme, converts fibrinogen, a protein substance, into fibrin, an insoluble protein that forms an intricate network of minute threadlike structures called fibrils and causes the blood plasma to gel. The blood cells and plasma are enmeshed in the network of fibrils to form the clot.
Coagulation: In medicine, the clotting of blood. The process by which the blood clots to form solid masses, or clots.
More than 30 types of cells and substances in blood affect clotting. The process is initiated by blood platelets. Platelets produce a substance that combines with calcium ions in the blood to form thromboplastin, which in turn converts the protein prothrombin into thrombin in a complex series of reactions. Thrombin, a proteolytic enzyme, converts fibrinogen, a protein substance, into fibrin, an insoluble protein that forms an intricate network of minute threadlike structures called fibrils and causes the blood plasma to gel. The blood cells and plasma are enmeshed in the network of fibrils to form the clot.
Coagulation: In medicine, the clotting of blood. The process by which the blood clots to form solid masses, or clots.
More than 30 types of cells and substances in blood affect clotting. The process is initiated by blood platelets. Platelets produce a substance that combines with calcium ions in the blood to form thromboplastin, which in turn converts the protein prothrombin into thrombin in a complex series of reactions. Thrombin, a proteolytic enzyme, converts fibrinogen, a protein substance, into fibrin, an insoluble protein that forms an intricate network of minute threadlike structures called fibrils and causes the blood plasma to gel. The blood cells and plasma are enmeshed in the network of fibrils to form the clot.
Coagulation: In medicine, the clotting of blood. The process by which the blood clots to form solid masses, or clots.
More than 30 types of cells and substances in blood affect clotting. The process is initiated by blood platelets. Platelets produce a substance that combines with calcium ions in the blood to form thromboplastin, which in turn converts the protein prothrombin into thrombin in a complex series of reactions. Thrombin, a proteolytic enzyme, converts fibrinogen, a protein substance, into fibrin, an insoluble protein that forms an intricate network of minute threadlike structures called fibrils and causes the blood plasma to gel. The blood cells and plasma are enmeshed in the network of fibrils to form the clot.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
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 .
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.