Tissue culture is the process of growing cells, tissues or organs in an artificial sterile environment outside of their natural biological context. It involves taking a small tissue sample and growing it in a nutrient medium under controlled conditions. The first successes in tissue culture came in the early 1900s. There are two main types - primary cultures which use fresh tissue and can model natural function, and immortal cell lines. Tissue culture is used for both plant and animal cells, with applications like cloning plants, conserving endangered species, producing vaccines and pharmaceuticals, and studying cell biology.
1. Introduction: Tissue Culture is the in vitro culture of cells, tissues, organs or whole plant under controlled nutritional and environmental Conditions(T. Thorp, 2007).
The science of plant tissue culture takes its roots from the discovery of Cells (Robert Hooke in 1665) and propounding of cell theory.
In 1838, Schleiden and Schwann proposed that cell is the basic structural unit of all living organisms. They visualized that cell is capable of autonomy and therefore it should be possible for each cell if given an environment to regenerate into whole plants.
2. Plant Tissue Culture: Past & Present Prospects
In 1902, a German physiologist, Gottieb Haberlandt for the first time attempted to culture isolated single palisade cells from leaves in knop’s salt solution.
The cell remained alive for up to 1 month, increased in size, accumulated starch but failed to divide.
Though he was unsuccessful but he laid the foundation of tissue culture so he is regarded as Father of Plant Tissue Culture.
In the Subsequent years different landmark discoveries were made. Some of them are:
Use of specialized media for aseptic culture of Orchid seeds (Knudson, 1925) and other workers also demonstrated that plants could be propagated in vitro from the minuscule seeds of the Orchidaceae.
Further culture of other plant tissue was not possible due to lack of knowledge of the specific hormones to be added to the culture media.
This limitation was overcomed by the elucidation of the nature of Auxin, IAA, by Thimann and Went(1930) that plants would be subsequently regenerated through the use of IAA or its analogs.
Discovery of Cytokinins, specially Kinetin(6-furfurylaminopurine) by Miller et al. (1956), the regeneration of intact plants from tissue of many herbaceous species became a practical reality.
1. Introduction: Tissue Culture is the in vitro culture of cells, tissues, organs or whole plant under controlled nutritional and environmental Conditions(T. Thorp, 2007).
The science of plant tissue culture takes its roots from the discovery of Cells (Robert Hooke in 1665) and propounding of cell theory.
In 1838, Schleiden and Schwann proposed that cell is the basic structural unit of all living organisms. They visualized that cell is capable of autonomy and therefore it should be possible for each cell if given an environment to regenerate into whole plants.
2. Plant Tissue Culture: Past & Present Prospects
In 1902, a German physiologist, Gottieb Haberlandt for the first time attempted to culture isolated single palisade cells from leaves in knop’s salt solution.
The cell remained alive for up to 1 month, increased in size, accumulated starch but failed to divide.
Though he was unsuccessful but he laid the foundation of tissue culture so he is regarded as Father of Plant Tissue Culture.
In the Subsequent years different landmark discoveries were made. Some of them are:
Use of specialized media for aseptic culture of Orchid seeds (Knudson, 1925) and other workers also demonstrated that plants could be propagated in vitro from the minuscule seeds of the Orchidaceae.
Further culture of other plant tissue was not possible due to lack of knowledge of the specific hormones to be added to the culture media.
This limitation was overcomed by the elucidation of the nature of Auxin, IAA, by Thimann and Went(1930) that plants would be subsequently regenerated through the use of IAA or its analogs.
Discovery of Cytokinins, specially Kinetin(6-furfurylaminopurine) by Miller et al. (1956), the regeneration of intact plants from tissue of many herbaceous species became a practical reality.
PLANT TISSUE CULTURE
CONTENTS:
1. Historical Development of Plant Tissue Culture
2. Nutritional requirements, growth and their maintenance
3. Type of cultures
4. Application of plant tissue cultures tissue in pharmacognosy
5. Edible Vaccines
The ability of an explant to regenerate into a whole plant under in vitro asceptic conditions by providing a proper artificial nutrient medium is called as Plant Tissue Culture.
PLANT TISSUE CULTURE
CONTENTS:
1. Historical Development of Plant Tissue Culture
2. Nutritional requirements, growth and their maintenance
3. Type of cultures
4. Application of plant tissue cultures tissue in pharmacognosy
5. Edible Vaccines
The ability of an explant to regenerate into a whole plant under in vitro asceptic conditions by providing a proper artificial nutrient medium is called as Plant Tissue Culture.
cellular totipotency and callus cultureNeha Kakade
This ppt comprises a detailed information about cellular totipotency and callus culture in plant tissue culture . It has its applications, significance and procedure described in it . This explains about the property of totipotency. It describes stages of callus culture. It also descibes history of plant tissue culture
Essay on Plant Tissue Culture Contents:
the Definition of Plant Tissue Culture.
the History of Plant Tissue Culture.
the Basic Requirements of Plant Tissue Culture.
the General Techniques of Plant Tissue Culture.
the Basic Aspects of Plant Tissue Culture.
the Cellular Totipotency.
the Differentiation.
the Methods in Plant Tissue Culture.
the Applications of Plant Tissue Culture.
the Morphogenesis.
the Subculture or Secondary Cell Culture.
the Soma-Clonal Variation.
the Somatic Hybrids and Cybrids.
the Micro-Propagation.
the Artificial Seed.
the Cryopreservation.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
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.
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.
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.
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 .
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.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
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.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
3. Tissue culture:
◦ Tissue culture is also known as
MICROPROGATION Or vitro culture.
◦ The growing of plants Cells, tissue, Organs,
Seeds or others plants Parts in Sterile
environment On a nutrition.
• This is typically facilitated via use of a liquid,
semi-solid, or solid growth medium, such
as plant tissue culture being used for
plants. Broth and Agar.
• Tissue culture commonly refers to the culture
of animal cells and tissues, with the more
specific term plant tissue culture being used
for plants.
4. ◦ Tissue culture was made in 1885 by German
zoologist Wilhelm Roux who cultivated tissue from a
chick embryo in a warm salt solution.
◦ The first real success came in 1907, however, when American
zoologist Ross G. Harrison demonstrated the growth of
frog nerve cell processes in a medium of clotted lymph.
◦ French surgeon Alexis Carrel and his assistant Montrose
Burrows subsequently improved upon Harrison’s technique,
reporting their initial advances in a series of papers
published in 1910–11. Carrel and Burrows coined the
term tissue culture and defined the concept.
5. ◦Tissue culture, a method of
biological research in which fragments
of tissue from an animal or plant are
transferred to an artificial environment in
which they can continue to survive and
function.
◦ The cultured tissue may consist of a
single cell, a population of cells, or a
whole or part of an organ.
◦ Cells in culture may multiply; change
size, form, or function; exhibit specialized
activity (muscle cells, for example, may
contract); or interact with other cells.
6. Preparation:
◦ To initiate a culture, a tiny sample of the tissue is dispersed on or in
the medium, and the flask, tube, or plate containing the culture is then
incubated, usually at a temperature close to that of the tissue’s normal
environment.
◦ Sterile conditions are maintained to prevent contamination with
microorganisms. Cultures are sometimes started from single cells,
resulting in the production of uniform biological populations
called clones
◦ Single cells typically give rise to colonies within 10 to 14 days of being
placed under culture conditions.
7. There are two main types of cultures:
◦ Primary (mortal) cultures and cultures of established
(immortal) cell lines.
◦ Primary cultures consist of normal cells, tissues, or organs
that are excised directly from tissue collected by biopsy from
a living organism.
◦ Primary cultures are advantageous in that they essentially
model the natural function of the cell, tissue, or organ under
study.
◦ However, the longer the samples are maintained in culture,
the more mutations they accumulate, which can lead to
changes in chromosome structure and cell function.
8. Type of tissue culture
◦PLANT TISSUE CULTURE.
◦ANIMAL TISSUE CULTURE.
11. ◦ The production of exact copies of plants that produce particularly good flowers,
fruits, or have other desirable traits.
◦ To quickly produce mature plants.
◦ The production of multiples of plants in the absence of seeds or necessary
pollinators to produce seeds.
◦ The regeneration of whole plants from plant cells that have been genetically
modified.
◦ The production of plants in sterile containers that allows them to be moved with
greatly reduced chances of transmitting diseases, pests, and pathogens.
◦ The production of plants from seeds that otherwise have very low chances of
germinating and growing, i.e. orchids and Nepenthes.
◦ To clean particular plants of viral and other infections and to quickly multiply
these plants as 'cleaned stock' for horticulture and agriculture.
16. Animal tissue culture
◦Animal tissue culture products depends on
their efficacy, cost effectiveness and the
potential for scale-up.
◦ Recent and current advances in tissue
culture science have enhanced the
complexity in the design of biomaterials
which have either been proposed or utilized
to grow animal cells.
17. ◦ Many products of biotechnology (such as viral vaccines)
are fundamentally dependent on mass culturing of
animal cell lines. Although many simpler proteins are
being produced using rDNA in bacterial cultures, more
complex proteins that are glycosylated (carbohydrate-
modified) currently have to be made in animal cells.
◦ At present, cell culture research is aimed at investigating
the influence of culture conditions on viability,
productivity, and the constancy of post-translational
modifications such as glycosylation, which are
important for the biological activity of recombinant
proteins.
◦ Biologicals produced by recombinant DNA (rDNA)
technology in animal cell cultures include anticancer
agents, enzymes, immunobiologicals [interleukins,
18. ◦ 1.The study of basic cell biology, cell cycle mechanisms, specialized cell
function, cell–cell and cell–matrix interactions.
◦ 2.Toxicity testing to study the effects of new drugs.
◦ 3.Gene therapy for replacing nonfunctional genes with functional gene-carrying
cells.
◦ 4.The characterization of cancer cells, the role of various chemicals, viruses,
and radiation in cancer cells.
◦ 5.Production of vaccines, mABs, and pharmaceutical drugs.
◦ 6.Production of viruses for use in vaccine production (e.g., chicken pox, polio,
rabies, hepatitis B, and measles).
19. ◦ The commercial production of plants used as potting, landscape, and
florist subjects, which uses meristem and shoot culture to produce large
numbers of identical individuals.
◦ To conserve rare or endangered plant species.
◦ A plant breeder may use tissue culture to screen cells rather than plants
for advantageous characters, e.g. herbicide resistance/tolerance.
◦ Large-scale growth of plant cells in liquid culture in bioreactors for
production of valuable compounds, like plant-derived secondary
metabolites and recombinant proteins used as biopharmaceuticals.[8]
◦ To cross distantly related species by protoplast fusion and regeneration
of the novel hybrid.
◦ To rapidly study the molecular basis for physiological, biochemical, and
reproductive mechanisms in plants, for example in vitro selection for
stress tolerant plants.
20. ADVANTAGE:
◦The new plantlets can be grown in a short amount of
time.
◦Only a small amount of initial plant tissue is required.
◦The new plantlets and plants are more likely to be free of
viruses and diseases.
◦The process is not dependant on the seasons and can be
done throughout the year.
21. Disadvantages:
◦ Tissue Culture can require more labor and cost more money.
◦ There is a chance that the propagated plants will be less
resilient to diseases due to the type of environment they are
grown in.
◦ It is imperative that, before being cultured, the material is
screened; failure to pick up any abnormalities could lead to
the new plants
◦ There is still a chance that the process triggers a secondary
metabolic chemical reaction, and the new explants or cells' growth
gets stunted, or even die off.
◦ tissue culture is not a guarantee. There is still a chance that
the process triggers a secondary metabolic chemical reaction,
and the new explants or cells' growth gets stunted, or even die
off.