eChapters

Injudicious and indiscriminate use of several agrochemicals viz. pesticides, herbicides, insecticides, dyes and medicaments in the field of agriculture and veterinary practices threatens the human and animal population for the toxicity of these environmental deterrents. These agrochemicals have been associated with several episodes of accidental poisoning and mortality among human and animal population. The episode of Mass ethion poisoning in Gujarat is one of the commonest example of inclusion of pesticides or agrochemicals in the environmental pollutants. There are modern tools to evaluate and analyze these chemicals in the environmental pollutants of human and animal use. The sensitivity of these modern highly sophisticated tools has now immensely changed the analytical environmental pollutants industry. Gas chromatography and Mass Spectrophotometry i.e. (GC-MS) technique is employed to detect the volatile residues from environmental pollutants. Whereas, High performance liquid chromatography i.e. HPLC is employed to analyse and detect non volatile drug residues. Gas Chromatography/Mass Spectrometry (GC/MS) instrument separates chemical mixtures (the GC component) and identifies the components at a molecular level (the MS component). It is one of the most accurate tools for analyzing environmental samples.

Mesenchymal Stem Cells

Recent advances in the field of regenerative medicine have opened up newer therapeutic modalities using cell-based and cell-free therapies, particularly stem cells, as potential candidates. As per the definition, stem cells are the undifferentiated progenitor cells that can regenerate and can also differentiate into various specialized cells (Hoang et al., 2022). They can be classified as embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs) and postnatal adult stem cells (Locke et al., 2009). Among postnatal adult stem cells, mesenchymal stem cells (MSCs) have emerged as a popular choice of candidate for therapeutics due to the relatively easy availability, simple isolation techniques, low risk of teratogenicity, minimal ethical and legal concerns unlike embryonic stem cells, hence, are easy to apply in clinical research and practice (Voga et al., 2020). Among MSCs of different origin, bone marrow and particularly adipose tissue-derived stem cells (ADMSCs) received more attention and are one of the most common and promising stem cell types. These cells can be simply obtained from subcutaneous and omental fat or liposuction aspirates for the treatment of diverse clinical applications (Kim &Heo, 2014). These cells can also be expanded vigorously in vitro and differentiated into specific cell lineages such as adipocytes, osteoblasts, chondrocytes, and neurocytes and are even genetically stable in long-term cultures (Miana& González, 2018). Mesenchymal stem cells (MSCs) are multipotent progenitor cells possessing self-renewal ability (limited in vitro) and differentiation potential into mesenchymal lineages, according to the (ISCT) International Society for Cell and Gene Therapy (Dominici et al., 2006).

Introduction

Acute lung injury (ALI) is the manifestation of an inflammatory response of lung resulting from severe sepsis, bacterial or viral pneumonia, trauma, and burns in animals (Ali et al., 2020).It is distinguwashed by disruption to the alveolar capillary membranes, atelectasis of the pulmonary airspaces, and neutrophil and protein-rich fluid infiltration into the alveolar space (Li et al., 2019). Although advances in treatment, the disability and fatality rates of ALI remain high, that is around 30-40% (Ali et al., 2020). At the moment, new therapeutic alternatives are urgently required to treat ALI. As a result, this is a very active area of research to understand the molecular principles underlying pulmonary inflammation and ALI (Reiss et al., 2012). The use of animal models of inflammatory lung has allowed for the probing of pathways of inflammation responsible for injury. Specially, rodent models may serve a link between in vitro research to large animals and clinical studies by allowing for high quantities of samples under physiological circumstances at low expenses (Domscheit et al., 2020).LPS, found in the outer membrane of gram-negative bacteria, consists of a polar lipid head group (lipid A) and a chain of repeating disaccharides (Gao et al., 2023). LPS induced lung injury model, closely mimic sepsis and inflammatory lung diseases, is a well-establwashed model in this field of research (Reiss et al., 2012). To mimic acute lung injury, LPS can be administered either directly through intratracheal or intranasal route (direct pulmonary insult) or indirectly through intraperitoneally and intravenous routes (indirect extra pulmonary insult) (Perl et al., 2011). This chapter focuses mostly on rodent model of acute lung injury caused by lipopolysaccharide (LPS), both direct and indirect. Additionally, it also includes the characteristics and underlying molecular mechanism of LPS induced lung injury along with applications in drug development.

Spontaneous contractions of the uterus are controlled and coordinated for various reproductive functions. The non-pregnant uterus facilitates ova and sperm transport, provides adequate embryo placement for implantation, and contributes to the expulsion of menstrual debris through increased contractility, or periods of relative quiescence (Hutchings et al., 2009). Uterine dysmotility has been implicated in the pathogenesis of certain infertilities, implantation failure, endometriosis, dysmenorrhea, and abnormal menstrual events (Kunz and Leyendecker, 2002; Aguilar and Mitchell, 2010). Although these conditions may not contribute to mortality but can significantly affect patient’s reproductive health, and considerably alter their quality of life (Jones et al., 2004; Weissman et al., 2004; Chachamovich et al., 2010). Dysmenorrhoea refers to the occurrence of painful cramps in the lower abdominal region during menstruation and is one of the unresolved gynecological disorders in adolescent girls and women of reproductive age (Wang et al., 2004; Harel, 2008). This condition is mainly characterized by cramping pain in the lower abdomen immediately before or during menstruation, which does affect the quality of their life and work (Davis and Westhoff, 2001).

Terminal deoxynucleotidyl transferase (dUTP) nick end labeling (TUNEL) is a method for detecting DNA fragmentation by labeling the terminal end of nucleic acids. TUNEL is a common method for detecting DNA fragmentation that results from apoptotic signaling cascades. The assay relies on the presence of nicks in DNA which can be identified by terminal deoxynucleotidyl transferase or TdT, an enzyme that will catalyze the addition of dUTPs that are secondarily labeled with a marker. Here we perform the apoptotic assay test by TUNEL assay kit to identify the apoptotic property of any agent or chemical after treatment of primary cells culture at different concentration as per protocol provided with TUNEL Assay Kit and apoptotic cells are identified by using fluorescent microscope. Detailed procedure of TUNEL assay is as follows:

1. Preparation of primary cells culture as described in earlier methods.

2. Induction of apoptosis in primary cells culture is done by treatment of primary cells culture with different concentration of xenobiotics and incubation in CO2 incubator for 12 h as mentioned in micronuclei assay method.

3. The positive and negative control cells provided with the kit are already f ixed. However, negative control cells are prepared from control sample with absence of inducing agent.

4. Cell Fixation: Cell fixation is a required step in the TUNEL assay and it is done according to the procedure mentioned in the supplied kit by using paraformaldehyde solution. Suspend 1–2 × 106 cells (treated) in 0.5 ml of phosphate-buffered saline (PBS) and the cell suspension into 5 ml of 1% (w/v) paraformaldehyde in PBS and place on ice for 15 minutes.

5. Centrifuge the cells for 5 minutes at 300 × g and discard the supernatant.

Genotoxicity potential of any environmental pollutants can be investigated using the micronucleus (MN) test. It is among the most sensitive DNA damage indicators and it has been applied to several organisms and tissues for evaluation of environmental contaminants (Lemos et al., 2011). Micronuclei (MN) assay is more rapid and simpler than chromosomal analysis (Gandhi et al., 2003). Compared to the chromosome aberrations, the final result is relatively easily scored and thus requires less time to make an assessment of the clastogenicity of a chemical (Garriott et al. 2002). An in vitro MN assay can detect the clastogens and aneugens as well as mitotic delay, apoptosis, chromosome breakage, chromosome loss and non-disjunction (Corvi et al., 2008). Although, micronuclei constitute well-characterized biomarkers of chromosomal damage (Salazar et al. 2009) but in vitro MN test does not provide information on the origin of micronuclei (Corvi et al., 2008).

Experimental Procedure

Micronuclei assay is carried out in PMNC and splenocytes as per method of Hayashi et al. (1983).

The concept of single cell micro-gel electrophoresis (SCGE)/comet assay is f irst introduced by Ostling and Johanson (1984) as a method to measure DNA single-strand breaks under neutral conditions. Singh et al. (1988) modified this technique by using alkaline conditions (>13 pH) of electrophoresis, which enabled detection of not only frank strands breaks but also alkali labile sites, DNA cross- linking and incomplete excision repair sites. Now-a-days, this technique is extensively used to study the genotoxic effects of various chemicals. The advantages of SCGE technique include: (1) collection of data at the level of individual cell, allowing for more robust types of statistical analysis; (2) need for small number of cells per sample (<10,000); (3) its sensitivity for detecting DNA damage; and (4) that virtually any eukaryotic cell population is amenable to analysis. The idea is to combine DNA gel electrophoresis with fluorescence microscopy to visualize migration of DNA strands from individual agarose-embedded cells. If the negatively charged DNA contained breaks, DNA supercoils are relaxed and broken ends are able to migrate toward the anode during a brief electrophoresis. If the DNA is undamaged, the lack of free ends and large size of the fragments prevented migration. Determination of the relative amount of DNA that migrated provided a simple way to measure the number of DNA breaks in an individual cell.

Genotoxic effects of any xenobiotics in PMNC and splenocytes of Wistar rats can be studied according to the working protocol of Dhawan et al.

Apoptosis is triggered by extrinsic and intrinsic stimuli as radiation, oxidative stress and genotoxic chemicals. It is defined by characteristic changes in the nucleus morphology including chromatin condensation and fragmentation, overall cell shrinkage/rounding and formation of apoptotic cell bodies. Among the many markers of apoptosis, DNA fragmentation is considered a hallmark. The DNA ladder assay described here is a simple, sensitive, cost-effective and rapid method for estimating apoptosis in cells.

Isolation of Genomic DNA

Genomic DNA from primary cells culture of PMNC and splenocytes of rats is isolated by using standard phenol-chloroform DNA isolation protocol of Sambrook and Russel (2001) as described below:

1. Preparation of primary cells culture of different cells, namely-PBMNCs, thymocytes and splenocytes form Wistar rats and viability checked by trypan blue dye exclusion test.

2. 106 cells/ml of primary cell culture is used and seeded in 24 well culture plates containing along with treatment with xenobiotics at different µM concentration.

3. Cell culture plates are incubated in CO2 incubator at 37°C with 5% CO2 for 12 hrs.

4. The cells are collected in 1.5 ml of micro centrifuge tube and centrifuged at 3200 rpm for 10 min at 4°C; supernatant is discarded and pellet is washed with PBS (pH 7.2).

5. DNA extraction buffer (500 µl/tube) is added in tubes. Gently tap to disperse the cell pellet in extraction buffer and keep in water bath for 1.0 hr at 37 °C (it is to ensure that pellet is completely suspended so that cells are accessible to SDS and Proteinase K).

6. 10 % SDS is added (20 µl/ml) to cell suspension and the tubes are gently mixed by inverting the tube. The contents of tube become viscous which indicates lysis of cells. After that sample is handled gently from onward to avoid shearing of DNA.

7. Proteinase K (15 µl) of 20 mg Proteinase K/ml of buffer is added in tubes in two pulse i.e. half the requirement is added to tube in 1st pulse, mixed gently end to end and kept in water bath at 50°C. After 3-4 hrs, the second pulse of the remaining amount of Proteinase K is added and tubes are incubated at 50°C overnight.

8. Equal volume of equilibrated phenol (Tris saturated phenol pH> 7.8 ) is added in the tubes next day morning. Mix the contents of tube gently by inverting the tube for 15 min till a light coffee coloured uniform solution without any balls of phenol is formed and then centrifuge at 3400 rpm for 15 min.

Safety is a prime concern for humans and animals. Without evaluating the safety of a chemical, no regulatory authority in the world allows the chemical to be used by humans. There are stipulated guidelines for toxicity evaluations. Among the toxicity assays genotoxicity assays are important and have occupied centre stage due to increase in understanding of the genome.

Genotoxicity describes the property of chemical agents to damage the genetic information within a cell to cause mutations, which may even lead to cancer. While genotoxicity is often confused with mutagenicity, all mutagens are genotoxic; however, not all genotoxic substances are mutagenic. Generally and depending on the agent, a cytotoxic agent may be genotoxic (causing DNA damage), mutagenic (causing gene mutation) or it may be harmful for cell organelles (e.g. cell membrane) or it may even be teratogenic. Therefore, every cytotoxic agent is not genotoxic.

Why we Need to Evaluate Genotoxicity?

Toxicity can be at any level according to the nature of chemicals and type of exposure. Duration of toxicity can also be short lived or long lived within a generation or continue to next generation. Genotoxicity effects are able to continue in next generation(s), in which the exposed population may not suffer seriously but the next generation may suffer without being exposed to the same chemicals. Therefore, genotoxicity evaluations need serious attention.

Environmental agents (xenobiotics) that are injurious to cells trigger a spectrum of responses that can range from cell death to adaptation, repair, and proliferation. Cell death, in turn, can take the form of apoptosis (a programmed form of cell death). Xenobiotics have been implicated in toxic cell injury, among them free radicals (nitrogen, oxygen, and carbon derivatives) are known to interact with cellular constituents including membrane lipids and chromagen materials.

Cytotoxicity

Cytotoxic: Toxic to cells, cell-toxic, cell-killing. Any agent or process that kills cells. The prefix cyto- denotes a cell. It comes from the Greek “kytos” meaning hollow, as a cell or container. Toxic is from the Greek “toxikon” = arrow poison.

In nutshell, cell cytotoxicity refers to the ability of certain chemicals or mediator cells to destroy living cells. By using a cytotoxic compound, healthy living cells can either be induced to undergo necrosis (accidental cell death) or apoptosis (programmed cell death).

Measuring cytotoxicity can prove to be very valuable tool in identifying compounds that might pose certain health risks in humans and animals. Cytotoxicity assays are widely used by pharmaceutical industry to screen for cytotoxicity in compound libraries from initial high-throughput drug screens for unwanted cytotoxicity. This can be of vital importance and prove to be quite indispensable during research phase of developing therapeutic new pharmaceutical products to ensure the safety of end-users. Additionally, understanding the mechanisms involved in cytotoxicity can likewise give researchers a more in-depth knowledge on the biological processes (both normal and abnormal) governing cell growth, cell proliferation and death. Compounds that have cytotoxic effects often compromise cell membrane integrity. Therefore, assessing cell membrane integrity is one of the most common ways to measure cell viability and cytotoxic effects. There are three commonly used methods which can be employed to assess in vitro cytotoxicity (disruption of cell integrity) in cell cultures:

Cell culture refers to removal of cells from an animal or plant and their subsequent growth in a favorable artificial environment. The cells may be removed from the tissue directly and disaggregated by enzymatic or mechanical means before cultivation, or they may be derived from a cell line or cell strain that has already been establwashed.

Primary culture refers to the stage of culture after the cells are isolated from tissue and proliferated under appropriate conditions until they occupy all of the available substrate (i.e., reach confluence). At this stage, the cells have to be subcultured (i.e passaged) by transferring them to a new vessel with fresh growth medium to provide more room for continued growth.

Pharmaceutical and chemical industries depend largely on toxicological evaluations to provide information regarding safety of their commercial products. Toxicologists so far have been relying on animal studies to investigate potentially beneficial or harmful effects of drugs and chemicals prior to testing them in humans. Traditionally, the safety assessment process during drug development has been based on screening indiscriminately a plethora of new chemical entities (NCEs) using large number of animals as testing models in order to identify new therapeutic agents with the expectation that one or a few of these NCEs have some competitive advantages over the existing therapeutic agents. That is why they are more efficacious, bioavailable, selective, and safer. This approach is costly, time-consuming, and requires large quantities of test material. Currently, it takes about 10-12 years and a huge expenditure for a drug to move from research laboratory to patent. Thus alternative cell culture models in the early phases of drug discovery process can save time and money both by eliminating least beneficial NCEs.

Vitamins are natural and indispensable nutrients that are essential for our bodies in small quantities. Vitamins are indispensable for a multitude of biological functions, including growth, development, wound healing, maintaining healthy bones and tissues, supporting the immune system, and more. These vital organic compounds exhibit diverse biochemical functions and are essential for metabolic processes. The discovery of vitamins dates back to 1912 when Casimir Funk, a Polish American biochemist, initiated research on their sources, functions, and deficiency disorders. Because of his groundbreaking work, Funk is widely recognized as the pioneer of vitamins.

Types of vitamins

The classification of vitamins is determined by their solubility, resulting in two distinct groups: fat-soluble vitamins and water-soluble vitamins.

Fat-soluble vitamins

Fat-soluble vitamins, as their name implies, need fat for absorption and are stored in the fat cells. These vitamins include Vitamin A, D, E, and K.

Enzymes are biocatalysts that play a crucial role in accelerating chemical reactions without undergoing any changes themselves. Enzymes enhance the rate of a reaction by reducing its activation energy without affecting the equilibrium position of the reaction. These catalysts specifically target molecules called substrates and convert them into different molecules known as products. Most enzymes have a proteinous nature, and some have a ribonucleic acid nature (like ribozymes and peptidyl-transferase), showing high substrate and stereo-specificity. Enzyme catalysis is indispensable for the majority of metabolic processes in cells, as it ensures that these processes occur at a rate that is sufficient to sustain life. The progression of metabolic pathways heavily relies on the catalytic activity of enzymes to facilitate individual steps.

The proteinous enzymes are classified into simple and conjugated enzymes.

1. Simple enzymes: Enzymes are made up of only protein components.

2. Conjugated enzymes: Enzymes comprise both protein (apoenzyme) and non-protein components (cofactor).

Nucleic acids are complex, chain-like polymers consisting of nucleotides as their monomers. Due to this characteristic, they are often referred to as polynucleotides. The largest molecules present in the biological system are nucleic acids. The two main types of nucleic acids are DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). The bulk of DNA is confined to the nucleus and some cell organelles like mitochondria and chloroplast. RNA is found in both the nucleus and cytoplasm. In 1869, Johannes Friedrich Miescher isolated a substance from the nuclei of the pus cell (leukocytes). The extracted material was named nuclein, which contained an unusually large amount of phosphorus; in addition to proteins, and devoid of sulfur. Richard Altman later named the nuclein as nucleic acid. These organic molecules are found in living cells and play a crucial role in transmitting genetic information from one generation to another.

Nucleotides

Nucleotides serve as the fundamental constituents of nucleic acids. Nucleotides have flat planar and heterocyclic origin. Nucleotides are small molecules composed of three components:

1. Nitrogenous base,

2. Pentose sugar and

3. Phosphate group.

Proteins are composed of amino acids and are large molecules that play a crucial role in various biological processes. They are considered the fundamental building blocks of life due to their abundance in the body, constituting approximately 60% of the dry weight of cells. These complex biomolecules are intricately folded and twisted strands of amino acids, actively participating in vital life processes, including metabolism, locomotion, immune response intercellular signaling, and molecular identification. As macronutrients proteins are present in all living organisms and directly contribute to numerous metabolic pathways. It is important to note that proteins are unique to each organism, exhibit species specificity, and vary within different organs of the same organism. With 22 different amino acids, the properties of a protein molecule are determined by the specific arrangement of these amino acids. While plants can synthesize all the necessary amino acids for protein production, animals rely on external sources for certain amino acids. Proteins consist of amino acids connected through peptide bonds, formed by the linkage between the amino (NH2 ) group of one amino acid and the carboxyl (COOH) group of another amino acid.

Amino acids are organic molecules made up of carbon (C), hydrogen (H), oxygen (O), and nitrogen (N). However, sulfur (S) and selenium (Se) are also found in some cases. Amino acids are essential organic compounds that come together to create proteins, thus making them the fundamental building blocks of proteins. These biomolecules play vital roles in various biological and chemical processes within the human body and are essential for the growth and development of an individual.

Amino acids consist of an acidic group (-COOH), a basic group (-NH2 ), and a side chain (R) or a hydrogen (H) atom, all bonded to the carbon atom. The features of amino acids are due to the side chain because they differ only in their side chain. All amino acids have the same basic structure except proline, which has a cyclic structure.

Various forms of amino acids like alpha (α), beta (β), gamma (γ) or delta (σ) form are found. The position of the amino group (-NH2 ) determines the form of the amino acid, i.e., if the NH2 group is attached to the α-carbon, it is called α-amino acid; if β-carbon, it is called β-amino acid, and so on. Mostly, α-Amino acids are found as the numbering of amino acids is done from the carboxylic group (-COOH).

Lipids are a class of organic compounds composed of hydrogen (H), carbon (C), and oxygen (O) atoms. These classes of biomolecules come together to create the fundamental building blocks that shape and govern the structure and functionality of living cells. The term lipid was used by the German biochemist Wilhem Bloor in 1943. Lipids are heterogeneous groups of substances that are insoluble in polar (water) and soluble in non-polar (ether, benzene, and chloroform) solvents. Lipids are the esters of fatty acids and their derivatives. Lipids play a crucial role in both the plant and animal domains. They are widely distributed in plants, but lipids are primarily stored in animal adipose tissues.

Classification of lipids

Lipids are classified into four different groups, as shown below:

1. Simple lipids

2. Complex lipids

3. Derived lipids and

4. Miscellaneous lipids

Carbohydrates are the macronutrients consisting of carbon (C), hydrogen (H), and oxygen (O) atoms. In simpler terms, carbohydrates can be defined as polyhydroxy aldehydes or ketones or substances, which yield them on hydrolysis. The general formula of carbohydrates is Cn (H2 O)n , where n is the number of carbon atoms. In nature, carbohydrates are the most abundant biological molecules. In the human diet, carbohydrates are one of the main nutrients that provide energy to the body. The green plants, through the process of photosynthesis, synthesize the carbohydrates.

Classification of carbohydrates

Carbohydrates are also known as saccharides, originating from the Greek word sakcharon, which means sugar. However, not all saccharides have a sweet taste. Carbohydrates can be classified into three distinct groups: monosaccharides, oligosaccharides, and polysaccharides. The number of sugar units determines this classification.

Monosaccharides

Monosaccharides, or simple sugars, are the most basic carbohydrates. They are the monomers that serve as the building blocks for forming polymers or complex carbohydrates. Monosaccharides are the most simple carbohydrates possessing carbonyl groups, i.e., aldehyde (CHO) and ketone (C=O) groups with two or more hydroxyl (OH) groups. Monosaccharide has the generic formula Cn (H2 O)n, where n is the number of carbon atoms. Monosaccharides are sugars that cannot be hydrolyzed further to form simple carbohydrates. These crystalline solids without color dissolve in water but remain insoluble in non-polar solvents.

Introduction and Scope of Biochemistry

Biochemistry is the field of study that focuses on studying chemical reactions occurring within living organisms. It is a specialized branch that combines the principles of both chemistry and biology. In order to comprehend the molecular mechanisms behind every biological event, this multidisciplinary f ield incorporates elements of biology, chemistry, and physiology. The scope of biochemistry extends from the study of small molecules and their interactions within cells to the analysis of complex metabolic pathways, enzyme kinetics, and the structure and function of biomolecules.

One of the main goals of biochemistry is to elucidate the chemical reactions that take place in living systems and understand how they regulate key biological processes. Biochemists investigate the structure, function, and properties of various biomolecules, such as proteins, carbohydrates, lipids, and nucleic acids. It helps us to study how these biomolecules interact and contribute to the overall functioning of cells, tissues, and organisms.

Biochemistry also plays a vital role in various areas of research and practical applications. For instance, in medical biochemistry, scientists study the molecular basis of diseases to develop diagnostic tests and therapeutic interventions. They investigate the biochemical mechanisms underlying genetic disorders, cancer, metabolic, and infectious diseases. Thus, understanding the biochemical basis of diseases can lead to the development of targeted and personalized treatments.

Principle

Cell viability refers to the quantity of healthy cells in a sample, while cell proliferation is a crucial indicator for comprehending the mechanisms and pathways involved in the survival of cells or death following exposure to toxic substances. The methods used to assess viability are typically the same as those used to detect cell proliferation. Cell cytotoxicity and proliferation assays are commonly employed in drug evaluations to determine if the test compounds impact cell proliferation or exhibit direct cytotoxic effects. Cell viability can be determined by calculating the ratio of total live cells to the total number of cells (live and dead). Staining also helps to observe the general cell structure. Cell proliferation assay by MTT. Metabolically active cells reduce the yellow tetrazolium MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) through dehydrogenase enzymes to produce NADH and NADPH. The purple formazan produced inside the cell can be dissolved and measured using spectrophotometry. The MTT Cell Proliferation Assay quantifies cell proliferation rate and detects decreases in cell viability caused by metabolic events leading to apoptosis or necrosis. The MTT Reagent produces minimal absorbance values when no cells are present.

Principle

Adenoviral, oncoretroviral, and lentiviral vectors are commonly utilised for gene delivery in mammalian cell culture and in vivo. Additional important examples of viral gene transfer involve baculovirus and vaccinia virus vectors. Stable cell lines produced with lentivirus technology provide consistent, long-term protein expression compared to the short-term expression achieved through transient transfection. This chapter focuses on cell transformation by lentiviruses.

Equipment

a) Biosafety cabinet level 2 (B2)

b) Carbon Dioxide (CO2 ) Incubator (set to 37°C with a 5% CO2 in air atmosphere)

c) Refrigerated centrifuge

d) Refrigerator

e) Inverted Microscope

f) Micro pipettes (1-10 μl, 10-200 μl, 100-1000 μl)

g) -86°C/-80°C deep freezer h) Autoclave

i) Hot air oven

j) Filtration Assembly

Principle

The majority of cell lines are cultivated as monolayer adherent cells, meaning they only grow on the surfaces of culture vessels. However, there are particular cells that are non-adhesive and do not rely on external support for their growth, referred to as suspension cells. A suspension culture, is a cell culture where individual cells or small cell clusters grow and multiply in a stirred growth medium, forming a suspension. Subculturing, also known as passaging cells, involves transferring cells from a previous culture into fresh growth medium to allow the cell line to continue growing. Suspension cultures involve the suspension of cells in a liquid medium and agitation at a specific speed to ensure that the cells are uniformly exposed to nutrient media from every angle. This method prevents cell aggregation and enhances nutrient absorption, thereby promoting cell growth. The maintenance of these cultures is achieved by transferring the cells from the early stationary phase to a fresh medium through subculturing. During the incubation period, there is an increase in both cell division and cell enlargement, leading to rapid cellular growth. The viability of cells in the suspension decreases after the stationary phase due to the exhaustion of certain factors or the accumulation of toxic substances in the medium. This decrease in the viability of the cells further reduces the growth rate of the entire culture. Next, a portion of the cell suspension is added to the freshly prepared medium with the same composition.

Principle

Neutralization refers to the process of reducing or nullifying the effect of a specific component. Neutralization is a process in which the effects of viral antigens or viruses reduce through Ag-Ab reactions. Neutralizing antibodies are a specific type of antibodies that play a role in neutralization. Not all antibodies generated within our body possess the capability to impede the effects of antigens. Only antibodies with the ability to neutralize can prevent the uptake of viral particles by cells and counteract their effects. The virus neutralization assay is a serological test utilized to identify the existence and extent of functional systemic antibodies that hinder the ability of a virus to cause infection.

Media and Materials

Equipment

a) Biosafety cabinet level 2 (B2)

b) Carbon Dioxide (CO2 ) Incubator (set to 37°C with a 5% CO2 in air atmosphere)

c) Refrigerated centrifuge

d) Refrigerator e) Inverted Microscope

f) Micro pipettes (1-10 μl, 10-200 μl, 100-1000 μl)

g) -86°C/-80°C deep freezer

h) Autoclave

i) Hot air oven

j) Filtration Assembly

Principle

The plaque assay was developed in order to enumerate and quantify the infectivity of bacteriophages. This technique has been subsequently adapted for application in animal virology and has proven to be a dependable method for quantifying the concentration of various viruses that have been adapted for growth in cell cultures. This assay is designed to quantify the capacity of a solitary infectious virus to create a visible area of cell death on a layer of cultured cells. A plaque forms during the viral infection cycle, in which the host cell dies after viral replication. Some viruses cause cell lysis during replication, while others cause minimal damage to the cells. The plaque assay is a technique used to measure the quantity of viruses that cause the destruction of their host cells, resulting in cytopathic effects (CPE). During a plaque assay, the host cells and virus are briefly co-cultured to enhance the virus's attachment and entry into the host cell. Subsequently, the concoction is introduced into a partially solidified agar medium. The thick agar is poured onto a layer of "bottom agar" which supplies ample nutrients for the host cell. After one round of virus replication, an infected cell will undergo lysis, leading to the release of multiple new viruses. Within the gelatinous substance, these newly released viruses can only infect neighbouring cells. After a subsequent round of replication, these neighbouring cells will undergo lysis. The cells that manage to avoid infection will continue to proliferate. After a period of 24 to 48 hours, plates that were not contaminated with a virus will display a consistent layer of cells. The plates infected with a multitude of viruses exhibit plaques. Quantifying viral titer is essential for assessing viral infectivity. The determination can be made either by conducting a plaque assay or by calculating the infectious dose.

Principle

Red blood cell sticking (hemadsorption) can reveal the presence of certain viruses. This happens because these viruses, like influenza or measles, sprout proteins (hemagglutinin) on their infected host cells. These proteins act like Velcro, attracting red blood cells and causing them to cling to the surface. A hemadsorption assay uses this natural process to check for viruses. It's faster than waiting for the cells to show damage (cytopathic effect), allowing for earlier detection. Haemadsorbing viruses can be detected several days prior to the appearance of a cytopathic effect.

Equipment

a) Biosafety cabinet level 2 (B2)

b) Carbon Dioxide (CO2 ) Incubator (set to 37°C with a 5% CO2 in air atmosphere)

c) Refrigerated centrifuge

d) Refrigerator

e) Inverted Microscope

f) Micro pipettes (1-10 μl, 10-200 μl, 100-1000 μl)

g) -86°C/-80°C deep freezer h) Autoclave

i) Hot air oven

j) Filtration Assembly

Principle

The quantification of infectious virus particles is commonly achieved through the utilisation of the Median Tissue Culture Infectious Dose (TCID50) assay. The assay functions through the introduction of a serial dilution of the virus sample into cells in a 96 well plate format. The chosen cell type is specifically intended to exhibit a cytopathic effect (CPE), which refers to observable changes in morphology or cell death resulting from viral infection. Following a period of incubation, the cells are examined for cytopathic effects or cell death, and each well is categorised as either infected or uninfected. The concentration at which 50% of the wells exhibit a cytopathic effect (CPE) is employed to determine the 50% tissue culture infectious dose (TCID50 ) of the viral sample. The end point is the dose or dilution that infects or kills or shows CPE of the cells. The calculation can be performed using various mathematical techniques, such as the Spearman-Karber method or the Reed Muench method. The virus titer is quantified as the number of tissue culture infectious dose 50 (TCID50 ) per millilitre (ml). The non-cytopathic virus can be quantified by employing the fluorescent antibody test, immune-peroxidase assay, or other appropriate methodologies.

Principle

Unlike bacteria, which can be cultivated on an artificial nutrient medium, viruses rely on a living host cell for replication. Eukaryotic or prokaryotic host cells that have been infected with viruses can be used to produce viruses. Subsequently, the medium and cells can be collected and used as a virus source. The production of viruses usually consists of a two-step procedure: f irst, the growth of host cells, and then the production phase. Understanding the complex relationship between the host cell and virus is essential. Various crucial factors have been recognised, such as the concentration of host cells during infection and the multiplicity of infection (MOI).

Materials required

Equipment

a) Biosafety cabinet level 2 (B2)

b) Carbon Dioxide (CO2 ) Incubator (set to 37°C with a 5% CO2 in air atmosphere)

c) Refrigerated centrifuge

d) Refrigerator

e) Inverted Microscope

f) Micro pipettes(1-10 μl, 10-200 μl, 100-1000 μl)

g) -86°C/-80°C deep freezer

h) Autoclave

i) Hot air oven

j) Filtration Assembly

Principle

The one-step growth experiment refers to a scientific methodology. A study aimed at observing the molecular events that take place during viral reproduction. This elucidates the fundamental features of the virus replication process and determines the optimal multiplicity of infection and timing for virus harvest. The initiation of modern bacteriophage research can be traced back to the development of the one-step growth curve by Max Delbrück and Emory Ellis in 1939, which utilised the Escherichia coli-T4 bacteriophage system. One step growth curve consists of three clearly defined phases 1. Latent period refers to the initial phase of a process where no significant changes or activities are observed. 2. Burst or Rise period is the subsequent phase characterised by a sudden increase virus particle. 3. Plateau period is the following phase where a stable and constant level virus replication.

Materials required

Principle

Isolating the virus in a laboratory is the gold standard for diagnosing many viral infections. Virus isolation is a highly specialised technique used to diagnose viral infections and produce a stock of viruses for research purposes. The isolation of the virus relies on the suitability of the sample, the ability of the cells to allow entry, the successful replication of the virus, and the release of viral particles from the cells. The choice of cell lines is dependent upon the suspected viral disease and the availability of such cell lines in the laboratory.

Materials required

Equipment

a) Biosafety cabinet level 2 (B2)

b) Carbon Dioxide (CO2 ) Incubator (set to 37°C with a 5% CO2 in air atmosphere)

c) Refrigerated centrifuge

d) Refrigerator

e) Inverted Microscope

f) Water bath

g) -86°C/-80°C deep freezer

h) Autoclave

i) Hot air oven

j) Filtration Assembly

Introduction

Structural changes in host cells by the viral infection is referred as cytopathic effect (CPE) and the responsible virus is called cytopathogenic virus. As a virus hijacks a cell to make copies of itself, the cell goes through distinct changes in its chemistry and structure. These effects are easiest to see in lab grown cell cultures. The severity of the damage caused by the virus depends on the specific virus itself, the type of cell it infects, how many viruses infect each cell (MOI), and other factors.

The early stages of this damage, called cytopathic effects (CPE), can be spotted directly under a microscope without any dyes or special treatments. While various types of CPE exist in living cells, some signs of viral infection, like inclusion bodies, require staining the cells to be visible. We can classify viruses based on how quickly they cause visible damage (cytopathic effect) in cell cultures. Viruses are typically considered slow if it takes 4-5 days to see this effect in cultures with a low starting dose of virus (MOI). On the other hand, viruses are considered fast if the damage shows up in just 1-2 days under the same conditions. It is important to note that at a high MOI all CPE can occur rapidly. So all decisions about rate of CPE appearance should be based on the lowest MOI that produces CPE

Introduction

The protocol below describes the use of cell freezing methods involving an electric -80°C freezer for the cryopreservation of cell lines. ECACC routinely use a programmable rate-controlled freezer. This is the most reliable and reproducible way to freeze cells but as the cost of such equipment is beyond the majority of research laboratories the methods below are described in detail. If large numbers of cell cultures are regularly being frozen then a programmable rate-controlled freezer is recommended.

Materials

• Freeze medium (commonly 90% FBS, 10% DMSO or glycerol

• 70% (v/v) alcohol in sterile water

• PBS without Ca2+/Mg2+ • 0.05% trypsin/EDTA in HBSS, without Ca2+/Mg2+

• DMSO

Introduction

Peripheral blood mononuclear cells (PBMCs) consist of chiefly of lymphocytes and monocytes. Purified PBMCs are used in vitro to evaluate a variety of functions of lymphocytes viz; a) proliferation to mitogenic (PHA, Con-A) stimulation, b) monitoring of prior sensitization in antigen recall assays by scoring lymphocyte proliferation, c) immunophenotyping for surface markers as well as intracellular molecules in monocytes and lymphocytes etc. Activation of monocytes/macrophages by small molecules, cytokines and pathogen components can also be monitored. PBMCs can also be used for a variety of structural and functional studies for addressing issues in human immunology such as scoring for apoptosis and production of cytokines as well as other mediators in vitro.

Background information

Blood is a liquid mixture comprised of plasma, cells and proteins. The liquid portion, plasma, makes up half of the blood volume, and cells the other half. Isolation of lymphocytes is a common procedure in immunology and cell biology that involves separating and collecting lymphocytes.

Cell counting is the fundamental techniques in various fields of biology, medicine and biotechnology.

Importance of cell counting

1. Research: Cell counting is a critical component of biological and medical research. It helps scientists understand the behavior of cells in various contexts, such as studying cell proliferation, differentiation, and response to stimuli.

2. Disease diagnosis: Monitoring various medical conditions, including infections, autoimmune diseases, cancer and blood disorders. Complete blood counts (CBCs) are routinely used to assess the levels of different blood cell types and assess disease conditions.

3. Stem Cell Research: Cell counting plays a significant role in stem cell research, where precise quantification of stem cells is necessary for various applications, including regenerative medicine and tissue engineering.

4. Cell Culture: Cell counting is integral part to determine seeding density. Seeding of cells to available surface area for growth is important consideration for successful culture.

5. Cell-Based Assay: The cell-based assays are used for drug screening, toxicity testing, and evaluating the efficacy of new compounds. Accurate cell counts are essential to ensure the reliability of assay results.

What is subculture?

In cell culture, a process called subculturing, or passaging, keeps cells alive and growing. It involves taking cells from an existing container, removing the used medium, and placing them in a new container with fresh nutrients. This allows the cells to continue multiplying and creates more cells for research.

Adherent subculture protocol Cells nearing 80% coverage need splitting!

1. Warm things up: Get your media, detachment solution, and incubator ready at 98.6°F (37°C).

2. Safety first! Disinfect your work area and supplies inside a biosafety cabinet.

3. Gently rinse: Remove the old media and wash the cells with a salt solution at room temperature. Be careful not to dislodge the cells.

4. Detach the cells: Add a pre-warmed enzyme solution to detach the cells from the flask surface. Keep an eye on them to make sure it works (usually 2 minutes). Note: Not all cells need this enzyme, and it can be harmful to some.

5. Stop the enzyme: Once all the cells are detached, add a culture medium with serum to neutralize the enzyme.

6. Collect the cells: Transfer the cell suspension to a tube, rinse the flask with fresh medium to get all the cells, and add it to the same tube.

7. Spin it down: Centrifuge the cell suspension for 5 minutes at room temperature (1000 rpm).

8. Get ready for counting: Remove the liquid, loosen the cell clump, and resuspend the cells in a fresh medium at a good volume for counting.

9. Count your cells: Use a hemocytometer to count the cells and determine their health.

What is dermal fibroblast?

Skin fibroblasts are a type of cell found in the dermis, the middle layer of the skin. They are the most common cells in connective tissue and play a crucial role in maintaining the structural integrity of the skin. Fibroblasts are responsible for synthesizing and secreting extracellular matrix proteins such as collagen, elastin, and fibronectin, which provide support and elasticity to the skin. Additionally, fibroblasts play a role in wound healing by proliferating and migrating to the site of injury, where they aid in tissue repair and scar formation.

Aim: To prepare the primary cell culture of fibroblasts from canine skin.

Tools and instrument required for the procedure

1. Tissue collection box with ice cubes - To prevent contamination and maintain the stable temperature

2. Surgical Gloves - To prevent contamination

3. Tissue collection tube with 1X PBS - To collect sample

4. Laminar flow hood - To work in a sterile environment and prevent contamination

5. Cell culture dish - To digest the skin

6. Sterile 1000 μL and 200 μL pipette and tips-For accurate measurement and transfer of cell suspension and culture media.

7. Forceps - Fine-tipped forceps for handling and manipulating tissue.

8. Scalpel and blade holder - Scalpel for the dissection of skin tissue.

9. Surgical scissors - Chopping of the skin tissue

10. Falcon 70 μm cell strainer - To filter out undigested tissue debris and obtain a homogeneous cell suspension.

11. 15 ml and 50 ml Centrifuge tubes - To collect and centrifuge the digested cell suspension.

What is keratinocyte?

The epidermal layer consists of keratinocytes, melanocytes, Langerhans cells, and Merkel cells. Their major function is to produce Keratinocytes which are the most abundant cells in the epidermis, keratin protein. Keratinocyte synthesizes major structural components of the epidermal barrier through a programmed process of differentiation. They are present in the innermost layer of the epidermis (Eckert et al?, 1989). The epidermis is composed of several layers, stratum corneum (horny layer), stratum lucidum (clear layer), stratum granulosum (granular layer), stratum spinosum (prickle cell layer), and stratum basale (basal layer), from the outermost to the deepest layer respectively. The process of maturation and movement of the keratinocytes from the stratum basale to the stratum corneum is what we call epidermal differentiation.

Procedures for isolation of canine karatinocytes

When studying skin cells, isolating keratinocytes from tissue samples, such as skin biopsies, is a critical initial step. Here is a general guide on how to isolate keratinocytes:

What is primary cell culture?

In vitro culture of cells freshly obtained from the tissue is called primary cell culture. Unlike that of cell line, primary cell culture grows for a limited period of time. Examples, are primary mammary epithelial cells, primary hepatocyte culture.

Aim: To prepare the primary cell culture from chicken embryos.

Materials required for the primary cell culture

• 70% alcohol

• Cotton swabs

• Small beaker 20-50 ml

• Forceps

• Straight and required curved,

• 9 cm Petri dishes

• 11 day embryonated eggs

• Balanced Salt solution (BSS)

• 250 ml conical flask

• Magnetic centrifuge tubes

• Haemocytometer

• Growth medium with serum

• Culture flasks

In the realm of cell culture, the quality and composition of the growth media and reagents play a pivotal role in growth and sustaining cells in vitro. The preparation of these essential components requires precision, attention to detail, and adherence to the strict protocols to ensure optimal cellular growth, viability, and experimental reproducibility. This introduction serves as a foundational overview of the critical aspects involved in the preparation of media and reagents for cell culture experiments. Furthermore, the preparation of media and reagents for cell culture necessitates adherence to stringent quality control measures to ensure consistency and reproducibility across experiments. Validation of media batches, sterility testing, and periodic quality assessments are essential practic

Working Principle: An autoclave is a sealed device that creates a different environment from the outside world under extraordinarily high pressure (Auto + clave = automatic locking). It uses moist heat or saturated steam under pressure to kill microorganisms and heat-resistant endospores. Its function is compared to that of a pressure cooker, i.e., steam is used to create a high pressure environment. However temperature of autoclave or steam sterilizer is generally maintained at 121°C for 15-20 minutes that is achieved by raising the pressure inside the device. This high pressure increases the boiling point of water and therefore raises the temperature that is too high for the microbes to survive, so used for sterilization.

Types of Autoclave cycle

1. Liquid cycle: Liquids take time to sterilize as they have high heat capacity. It is based on the principle of pressurized steam at 15 psi, 121°C temperature for 20 minutes. It has latent heat, which is 7× heat 100°C. Liquids and biological waste require slow exhaust to prevent the boiling over of super-heated liquids. This excess temperature is enough to hydrolyze the proteins of bacteria, viruses, or any other contaminant and therefore kill it. However, wet heat is seven times more intense than dry heat, so it requires less temperature than the dry heat cycle of the autoclave.

2. Dry Cycle: Here, steam is the sterilization medium, which penetrates inside the load and makes contact with all the surfaces, so a fast exhaust cycle is used. It has a high temperature of 160°C for 60 minutes.

Things required for cell culture

1. Lab – having negative pressure (HEPA filter)

2. Safety cabinet (Hood/laminar flow)

a) Biosafety level 1 (BSL-1) – Basic level of protection. Agents handled under this cabinet are NOT infectious.

b) BSL-2 – Appropriate for moderate risk agents. Most of the non infectious cell cultures are done under this facility.

The tissue/cell culture lab has the requirement of maintaining an aseptic environment. There are several aspects to the design of good tissue culture facilities. Ideally, cell culture work should be conducted in a single-use facility. Therefore, cell culture lab unit should be separated from the rest of the lab area. It can be either separate lab or a closed partition in a big lab. All new material should be handled as ‘quarantine’ material in a separate area, and materials known to be free of contaminants should only be allowed inside the culture room. In addition, the work surfaces should be thoroughly cleaned and disinfected between activities.

For most of the work involving non-infectious primary culture and cell lines, the laboratory should be designated to at least BSL2 facility. The location of the Biosafety cabinet is the most important point to consider. When operated correctly, the cabinet will provide a clean working environment, whilst protecting the operator from aerosols. Environmental monitoring with Tryptone Soy Broth agar settle plates inside the biosafety cabinet is a good indicator of the cleanliness of a cabinet. There should be no growth of bacteria and fungi after 3-5 days of incubation.

Clinical Symptoms

• White/brown cotton-like foci on the surface of the skin and/or gills

• Peritonitis

• Extensive haemorrhage • Necrosis

• Adhesions

Clinical Symptoms

• Anchor worms can be seen with the naked eye

• Frequent rubbing or “flashing”

• Localised redness

• Inflammation on the body of the fish

• Tiny white-green or red worms in wounds

• Breathing difficulties

Clinical Symptoms • External haemorrhages

• Pale gills • Ascites

• Destruction of tissues in the kidney, spleen, and liver

• Excessive mucus secretion

• Skin hemorrhages with edema of the tissues

• Skin ulceration around the mouth and base of the fins

Causative Agent: Rhabdovirus

Host (Common sp.)

• Common carp

• Koi carp

• Crucian carp

• Silver carp

• Bighead carp

• Grass carp

• Goldfish

Clinical Symptoms

• Gasping for air

• Discoloured gills with trapped materials

• Swollen gills with enhanced mucous secretion

• White to grey spots on the gills

• Diseased fish gather near the outlet of the pond

• Fish become lethargic and remain on the surface waters

Causative Agent: Flavobacterium branchiophilum, Cytophaga spp., Flexibacter spp.

Host (Common sp.)

• Goldfish • Koi carp

• Cichlids • Fighter fish

• Gourami fish

A key challenge for the years to come is feeding a rapidly growing human population while lowering the impact of food production on the environment. This is particularly true for low and middle-income countries where the demand for animal protein is likely to rise and further increase several folds in existing environmental changes (e.g., droughts, floods, extensive wildfires) have in recent years led to major food crises. To achieve these goals, food production not only needs to be increased, but most of all, good husbandry practices must be followed to reduce its negative impacts on the environment. Several studies have suggested that shifting the human diet towards increased consumption of f ish and seafood could be a solution to the need for protein that would sustain human and environmental health. In fact, fish and seafood consumption is forecast to increase by 27% on the horizon of 2030, mostly sustained by the aquaculture sector, which is expected to grow by 62% during the same period. The aquaculture industry contributes significantly to livelihood, food security, and poverty alleviation, with over 100 million people estimated to rely on aquaculture for their living. Fish is a cheap source of animal protein, and the current per capita consumption of fish in India is around 9 kg per annum, which is compared to the 11 kg recommended by the World Health Organisation (WHO). Presently, the contribution of the fisheries sector to the gross domestic product (GDP) and agriculture GDP has been estimated to be 1.2 and 4.2%, respectively.

Vitamins are naturally occurring, vital nutrients that are needed in small amounts. They are important for bone and tissue health, wound healing, growth and development, immune system function, and other biological processes. These vital organic substances serve a variety of biochemical purposes. Vitamins, like minerals, are not biosynthesized by the body. Consequently, in order to maintain our health, we must obtain them from the food we eat or, in rare circumstances, supplements.

Vitamins in Milk

Together with water- soluble vitamins like vitamin C and B complex and provitamins, milk also contains a variety of fat- soluble vitamins like A, D, E, and K. Some of these vitamins do, however, have very low concentrations.

Vitamin A (Retinol)

Plant foods contain carotenoids, which are the precursors of vitamin A, whereas animal foods provide preformed vitamin A in the form of retinyl esters.

The primary constituents of milk are water, fat, protein, sugar (lactose), minerals, vitamins, and enzymes. Milk is a thin emulsion made up of two phases: A continuous aqueous colloidal phase and a dispersed phase of oil or fat. It is an opaque white liquid containing fat in an emulsion, protein, and a few minerals in a colloidal suspension, and lactose along with soluble proteins and a few minerals in a true solution. The physical characteristics of milk are comparable to those of water, but they are altered by the degree of dispersion of the colloidal and emulsified components as well as the presence of different solutes, such as salts, lactose, and protein, in the continuous phase.

Physical Appearance, Color and Optical Properties

Fat globules and casein micelles scatter light, giving the appearance of turbid and opaque milk. The way that molecules scatter light has an impact on optical characteristics. When the wavelength of light and the particle’s magnitude coincide, light scattering happens. Consequently, light with shorter wavelengths is scattered by smaller particles and vice versa. Because casein micelles scatter blue light more than red light at shorter wavelengths, skim milk appears slightly blue. Cow’s milk has a creamy color because of beta- carotene, a carotenoid precursor to vitamin A. The greenish tinge in whey is due to the presence of riboflavin. Turbid and opaque due to scattering of light mainly by protein micelles and fat globules.

Electrophoresis

The mobility of ions in an electric field is the basis for the separation method known as electrophoresis. Ions that are negatively charged move toward a positive electrode, while those that are positively charged move toward a negative electrode. Usually, one electrode is biased either positively or negatively, and the other is at the ground for safety reasons. Ions can be distinguished from one another based on their size, shape, and overall charge, which determine their migration rates.

Poly Acrylamide Gel Electrophoresis (PAGE)

Introduction

Electrophoresis is an electrochemical process in which substances with a net electric charge migrate under the influence of an electric current. This migration occurs in an agar gel or a liquid- filled buffered matrix such as cellulose acetate. Positively charged substances travel toward the cathode (negative electrode), while negatively charged substances go toward the anode (positive electrode). Different substances move at different rates depending on their charge. This movement is called electrophoretic mobility.

Proteins are charged molecules. They have a positive as well as a negative charge. Among proteins, particularly caseins, they have different contents. The charge density also varies depending on the molecular weight. Proteins have a net negative charge at a pH above 4.6, and hence they move towards the anode (positive electrode) when subjected to an electric field under alkaline conditions. Due to differences in the charge of individual protein fractions, their migration rates also differ and are hence separated into distinct bands. These bands are stained with the dye amido- black, destained with 7% acetic acid, and observed for the electrophoretic pattern.

Food adulteration is a global issue, and because there are insufficient regulations and oversight, developing nations are more vulnerable to it. But in many nations, food adulteration has gone unnoticed. Contrary to popular assumption, milk adulterants can, regrettably, present major health risks that result in fatal diseases. Modern milk adulteration involves increasingly complex techniques, necessitating state- of- the- art research to identify the adulterants. Because milk contains so many nutrients that are needed by both adults and infants, it is referred to as the ideal food. In terms of protein, fat, carbohydrates, vitamins, and minerals, it is among the best sources. Regretfully, milk adulteration is a very common problem worldwide. Potential causes could be the gap between supply and demand, the perishable nature of milk, the low purchasing power of the consumer, and the absence of appropriate detection tests. Because there is insufficient oversight and inadequate law enforcement, the situation is substantially worse in developing and underdeveloped nations. While quantitative detections of adulterants in milk are varied and complex, qualitative detections can be carried out simply using chemical reactions. The type of quantitative detection methods used depends on the milk’s adulterants.

Typical Adulterants in Milk

The addition of vegetable protein, milk from different species, whey addition, and watering are the main adulterants in milk that are known to be economically motivated. There is no serious health risk associated with these adulterations. Some adulterants, though, are too dangerous to ignore. Urea, formalin, detergents, ammonium sulfate, boric acid, caustic soda, benzoic acid, salicylic acid, hydrogen peroxide, sugars, and melamine are a few of the main adulterants in milk that have been shown to have serious negative health effects.