This document discusses the differences between gram positive and gram negative bacterial cell walls. Gram positive bacteria have a thick peptidoglycan layer (20-80nm) in their cell wall containing teichoic acids, while gram negative bacteria have a thinner peptidoglycan layer (10nm) sandwiched between an inner and outer membrane. Gram staining is used to differentiate the two types based on their ability to retain crystal violet dye - gram positive bacteria retain the dye due to their thick peptidoglycan layer and appear violet, while gram negative bacteria lose the dye due to their thinner peptidoglycan layer and appear red with safranin counterstain. The staining protocol involves staining
antibodies are a large proteins. based on electrophorosis and centrifugation anti bodies are mainly five types .these are protects on human body from various microorganisms.
antibodies are a large proteins. based on electrophorosis and centrifugation anti bodies are mainly five types .these are protects on human body from various microorganisms.
Acid fast staining is differential staining technique which differentiate bacteria into two group- acid fast bacteria and non acid bacteria. It used to identify acid-fast organisms such as members of the genus Mycobacterium .
When fresh liquid medium is inoculated with a given number of bacteria and incubated for sufficient period of time, it gives a characteristic growth pattern of bacteria.
If the bacterial population is measured periodically and log of number of viable bacteria is plotted in a graph against time, it gives a characteristic growth curve which is known as growth curve or growth cycle.
Acid fast staining is differential staining technique which differentiate bacteria into two group- acid fast bacteria and non acid bacteria. It used to identify acid-fast organisms such as members of the genus Mycobacterium .
When fresh liquid medium is inoculated with a given number of bacteria and incubated for sufficient period of time, it gives a characteristic growth pattern of bacteria.
If the bacterial population is measured periodically and log of number of viable bacteria is plotted in a graph against time, it gives a characteristic growth curve which is known as growth curve or growth cycle.
The document briefs about the four commonly used staining techniques in the laboratory. It states the principle and identifies the color of the staining.
Gram staining Principle, Procedure, Reagents required for Gram Staining and t...Zunaira Gillani
Gram staining Principle, Procedure, Reagents required for Gram Staining and their Functions, Peptidoglycan Structural difference in Gram positive and Gram Negative.
The Gram stain is a fundamental technique in microbiology used to classify bacteria based on their cell wall structure. It provides a quick and simple method to distinguish between Gram-positive and Gram-negative bacteria, which have different susceptibilities to antibiotics
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
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
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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.
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Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
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Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
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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.
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.
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.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
2. What is cell wall?
A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane.
It can be tough, flexible, and sometimes rigid. It provides the cell with both structural
support and protection, and also acts as a filtering mechanism.
Cell walls are present in most prokaryotes (except mollicute bacteria), in algae, fungi and
eukaryotes including plants but are absent in animals.
Bacterial cell walls are made of peptidoglycan , peptidoglycan is a primary component of
bacterial cell wall.
While cellulose was the primary component of plant cell wall.
PEPTIDOGLYCAN: unique macromolecule composed of a repeating framework of long glycan
chain cross-linked by short peptide fragment.
3. Chemical nature of bacterial cell wall:
Peptidoglycan is a made up of 2 amino sugars.
1.N-acetyl glucosamine [NAG]
2.N- acetylmuramic acid [NAM]
NAM attached 4 amino acid chain. The four amino acids that compose the tetrapeptide are: L-
alanine, D-glutamine, L-lysine or meso-diaminopimelic acid (DPA), and D-alanine.
4. Gram positive bacteria cell wall:
20-80 nm thick peptidoglycan
Includes teichoic acids and lipoteichoic acids.- function in cell wall maintainance and
enlargement during the cell division;move cation across the cell envelope;stimulate a specific
immune response.
Some cell have periplasmic space between the cell membrane and cell wall.
5. Function of gram positive bacteria cell wall
1. The peptidoglycan in the Gram-positive cell wall prevents osmotic lysis.
2. The teichoic acids probably help make the cell wall stronger.
3. The surface proteins in the bacterial peptidoglycan, depending on the strain and species,
carry out a variety of activities.
a. Some surface proteins function as enzymes.
b. Other proteins serve as adhesins. Adhesins enable the bacterium to adhere intimately to host
calls and other surfaces in order to colonize those cells and resist flushing.
6. Gram negative bacteria cell wall
Inner and outer membranes and periplasmic space between them contains a thin peptidoglycan
layer.
Outer membrane contains lipopolysaccharides[LPS].
Lipid portion endotoxin may become toxic when released during infection.
Contain porin protein in upper layer – regulate molecules entering and leaving cell.
Peptidoglycan layer 10 nm thickness.
9. What is gram staining?
Gram staining is a common technique used to differentiate two large groups of
bacteria based on their different cell wall constituents. The Gram stain
procedure distinguishes between Gram positive and Gram negative groups by
coloring these cells red or violet. Gram positive bacteria stain violet due to the
presence of a thick layer of peptidoglycan in their cell walls, which retains the
crystal violet these cells are stained with. Alternatively, Gram negative bacteria
stain red, which is attributed to a thinner peptidoglycan wall, which does not
retain the crystal violet during the decoloring process.
10. How Does Gram Staining Work?
Gram staining involves three processes: staining with a water-soluble dye
called crystal violet, decolorization, and counterstaining, usually with safranin .
Due to differences in the thickness of a peptidoglycan layer in the cell
membrane between Gram positive and Gram negative bacteria, Gram positive
bacteria (with a thicker peptidoglycan layer) retain crystal violet stain during
the decolorization process, while Gram negative bacteria lose the crystal violet
stain and are instead stained by the safranin in the final staining process. The
process involves three steps:
1. Cells are stained with crystal violet dye. Next, a Gram's iodine solution
(iodine and potassium iodide) is added to form a complex between the crystal
violet and iodine. This complex is a larger molecule than the original crystal
violet stain and iodine and is insoluble in water.
11. 2. A decolorizer such as ethyl alcohol or acetone is added to the sample, which
dehydrates the peptidoglycan layer, shrinking and tightening it. The large
crystal violet-iodine complex is not able to penetrate this tightened
peptidoglycan layer, and is thus trapped in the cell in Gram positive bacteria.
Conversely, the the outer membrane of Gram negative bacteria is degraded
and the thinner peptidoglycan layer of Gram negative cells is unable to retain
the crystal violet-iodine complex and the color is lost.
3. A counterstain, such as the weakly water soluble safranin, is added to the
sample, staining it red. Since the safranin is lighter than crystal violet, it does
not disrupt the purple coloration in Gram positive cells. However, the
decolorized Gram negative cells are stained red.
12. How To- Staining Protocol and Concerns:
Reagents:
Crystal violet (primary stain)
Iodine solution/Gram's Iodine (mordant that fixes crystal violet to
cell wall)
Decolorizer (e.g. ethanol)
Safranin (secondary stain)
Water (preferably in a squirt bottle)
13. PROCEDURE OR METHOD
1. Make a slide of cell sample to be stained. Heat fix the sample to
the slide by carefully passing the slide with a drop or small piece of
sample on it through a Bunsen burner three times.
2. Add the primary stain (crystal violet) to the sample/slide and
incubate for 1 minute. Rinse slide with a gentle stream of water for a
maximum of 5 seconds to remove unbound crystal violet.
3. Add Gram's iodine for 1 minute- this is a mordant, or an agent
that fixes the crystal violet to the bacterial cell wall.
14. 4. Rinse sample/slide with acetone or alcohol for ~3 seconds and
rinse with a gentle stream of water. The alcohol will decolorize the
sample if it is Gram negative, removing the crystal violet. However,
if the alcohol remains on the sample for too long, it may also
decolorize Gram positive cells.
5. Add the secondary stain, safranin, to the slide and incubate for 1
minute. Wash with a gentle stream of water for a maximum of 5
seconds. If the bacteria is Gram positive, it will retain the primary
stain (crystal violet) and not take the secondary stain (safranin),
causing it to look violet/purple under a microscope. If the bacteria
is Gram negative, it will lose the primary stain and take the
secondary stain, causing it to appear red when viewed under a
microscope.