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12.2: Biotechnology in Medicine and Agriculture - Biology

12.2: Biotechnology in Medicine and Agriculture - Biology


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It is easy to see how biotechnology can be used for medicinal purposes. Knowledge of the genetic makeup of our species, the genetic basis of heritable diseases, and the invention of technology to manipulate and fix mutant genes provides methods to treat diseases. Biotechnology in agriculture can enhance resistance to disease, pests, and environmental stress to improve both crop yield and quality.

Genetic Diagnosis and Gene Therapy

The process of testing for suspected genetic defects before administering treatment is called genetic diagnosis by genetic testing. In some cases in which a genetic disease is present in an individual’s family, family members may be advised to undergo genetic testing. For example, mutations in the BRCA genes may increase the likelihood of developing breast and ovarian cancers in women and some other cancers in women and men. A woman with breast cancer can be screened for these mutations. If one of the high-risk mutations is found, her female relatives may also wish to be screened for that particular mutation, or simply be more vigilant for the occurrence of cancers. Genetic testing is also offered for fetuses (or embryos with in vitro fertilization) to determine the presence or absence of disease-causing genes in families with specific debilitating diseases.

Gene therapy is a genetic engineering technique that may one day be used to cure certain genetic diseases. In its simplest form, it involves the introduction of a non-mutated gene at a random location in the genome to cure a disease by replacing a protein that may be absent in these individuals because of a genetic mutation. The non-mutated gene is usually introduced into diseased cells as part of a vector transmitted by a virus, such as an adenovirus, that can infect the host cell and deliver the foreign DNA into the genome of the targeted cell (Figure 10.2.1). To date, gene therapies have been primarily experimental procedures in humans. A few of these experimental treatments have been successful, but the methods may be important in the future as the factors limiting its success are resolved.

Production of Vaccines, Antibiotics, and Hormones

Traditional vaccination strategies use weakened or inactive forms of microorganisms or viruses to stimulate the immune system. Modern techniques use specific genes of microorganisms cloned into vectors and mass-produced in bacteria to make large quantities of specific substances to stimulate the immune system. The substance is then used as a vaccine. In some cases, such as the H1N1 flu vaccine, genes cloned from the virus have been used to combat the constantly changing strains of this virus.

Antibiotics kill bacteria and are naturally produced by microorganisms such as fungi; penicillin is perhaps the most well-known example. Antibiotics are produced on a large scale by cultivating and manipulating fungal cells. The fungal cells have typically been genetically modified to improve the yields of the antibiotic compound.

Recombinant DNA technology was used to produce large-scale quantities of the human hormone insulin in E. coli as early as 1978. Previously, it was only possible to treat diabetes with pig insulin, which caused allergic reactions in many humans because of differences in the insulin molecule. In addition, human growth hormone (HGH) is used to treat growth disorders in children. The HGH gene was cloned from a cDNA (complementary DNA) library and inserted into E. coli cells by cloning it into a bacterial vector.

Transgenic Animals

Although several recombinant proteins used in medicine are successfully produced in bacteria, some proteins need a eukaryotic animal host for proper processing. For this reason, genes have been cloned and expressed in animals such as sheep, goats, chickens, and mice. Animals that have been modified to express recombinant DNA are called transgenic animals (Figure 10.2.2).

Several human proteins are expressed in the milk of transgenic sheep and goats. In one commercial example, the FDA has approved a blood anticoagulant protein that is produced in the milk of transgenic goats for use in humans. Mice have been used extensively for expressing and studying the effects of recombinant genes and mutations.

Transgenic Plants

Manipulating the DNA of plants (creating genetically modified organisms, or GMOs) has helped to create desirable traits such as disease resistance, herbicide, and pest resistance, better nutritional value, and better shelf life (Figure 10.2.3). Plants are the most important source of food for the human population. Farmers developed ways to select for plant varieties with desirable traits long before modern-day biotechnology practices were established.


Figure 10.2.3: Corn, a major agricultural crop used to create products for a variety of industries, is often modified through plant biotechnology. (credit: Keith Weller, USDA)

Transgenic plants have received DNA from other species. Because they contain unique combinations of genes and are not restricted to the laboratory, transgenic plants and other GMOs are closely monitored by government agencies to ensure that they are fit for human consumption and do not endanger other plant and animal life. Because foreign genes can spread to other species in the environment, particularly in the pollen and seeds of plants, extensive testing is required to ensure ecological stability. Staples like corn, potatoes, and tomatoes were the first crop plants to be genetically engineered.

Transformation of Plants Using Agrobacterium tumefaciens

In plants, tumors caused by the bacterium Agrobacterium tumefaciens occur by transfer of DNA from the bacterium to the plant. The artificial introduction of DNA into plant cells is more challenging than in animal cells because of the thick plant cell wall. Researchers used the natural transfer of DNA from Agrobacterium to a plant host to introduce DNA fragments of their choice into plant hosts. In nature, the disease-causing A. tumefaciens have a set of plasmids that contain genes that integrate into the infected plant cell’s genome. Researchers manipulate the plasmids to carry the desired DNA fragment and insert it into the plant genome.

The Organic Insecticide Bacillus thuringiensis

Bacillus thuringiensis (Bt) is a bacterium that produces protein crystals that are toxic to many insect species that feed on plants. Insects that have eaten Bt toxin stop feeding on the plants within a few hours. After the toxin is activated in the intestines of the insects, death occurs within a couple of days. The crystal toxin genes have been cloned from the bacterium and introduced into plants, therefore allowing plants to produce their own crystal Bt toxin that acts against insects. Bt toxin is safe for the environment and non-toxic to mammals (including humans). As a result, it has been approved for use by organic farmers as a natural insecticide. There is some concern, however, that insects may evolve resistance to the Bt toxin in the same way that bacteria evolve resistance to antibiotics.

FlavrSavr Tomato

The first GM crop to be introduced into the market was the FlavrSavr Tomato produced in 1994. Molecular genetic technology was used to slow down the process of softening and rotting caused by fungal infections, which led to increased shelf life of the GM tomatoes. Additional genetic modification improved the flavor of this tomato. The FlavrSavr tomato did not successfully stay in the market because of problems maintaining and shipping the crop.

Summary

Genetic testing is performed to identify disease-causing genes, and can be used to benefit affected individuals and their relatives who have not developed disease symptoms yet. Gene therapy—by which functioning genes are incorporated into the genomes of individuals with a non-functioning mutant gene—has the potential to cure heritable diseases. Transgenic organisms possess DNA from a different species, usually generated by molecular cloning techniques. Vaccines, antibiotics, and hormones are examples of products obtained by recombinant DNA technology. Transgenic animals have been created for experimental purposes and some are used to produce some human proteins.

Genes are inserted into plants, using plasmids in the bacterium Agrobacterium tumefaciens, which infects plants. Transgenic plants have been created to improve the characteristics of crop plants—for example, by giving them insect resistance by inserting a gene for a bacterial toxin.

Glossary

gene therapy
the technique used to cure heritable diseases by replacing mutant genes with good genes
genetic testing
identifying gene variants in an individual that may lead to a genetic disease in that individual

Applications of Biotechnology in Agriculture

The following points highlight the four main applications of biotechnology in agriculture:- 1. Micro-propagation 2. Induction and Selection of Mutant 3. Production of Somatic Hybrids 4. Production of Transgenic Plants.

Application # 1. Micro-propagation:

Mass propagation of crop and forest plants is an important applica­tion of micro-propagation technique. The deve­lopment of embryos from somatic cells in culture resulted in artificial seed production.

This tech­nique involves three stages:

(a) Establishment of culture

(c) Transfer of plants from test tube to soil

Regeneration of plantlets in cultured plant cell and tissues has been achieved in many trees of high economic value. Many of the studies are aimed at large scale micro-propagation of impor­tant trees yielding fuel, pulp, timber, oils and fruits.

Therefore, clonal forestry and horticulture are gaining an increasing recognition as an alter­native for tree improvement. In recent years, the interest has aroused in commercializing the in vitro propagation of forest trees.

This will bring about refinement in the existing procedures to make micro-propagation more cost effective. For betterment and improvement of tree plants of high economic value, genetic transformation and in vitro regeneration have been done in many angiospermic and gymnospermic plants.

Application # 2. Induction and Selection of Mutant:

Different physical and chemical mutagens are used in the plant explants of different species to generate mutants. Now the mutants can be used to select out the variant cell lines which are resistant to antibiotics, amino acid analogues, chlorate, nucleic acid base analogue, fungal toxin, environmental stresses (salinity, chilling, high temperature, aluminum toxicity) and herbi­cides, etc.

Single cell or the protoplast culture systems have proved to be valuable for muta­genesis since the presence of discrete cells in these substances is more effective to cause muta­tion, and isolation of mutant line is more easier.

Application # 3. Production of Somatic Hybrids:

The pro­toplasts can undergo fusion under certain favou­rable conditions and the fused product can give rise to somatic hybrid plant which offers:

(a) The possibility of hybrid formation of widely unrelated forms,

(b) An asexual means of gene transfer either of whole genome or of partial genome.

Through successful production of hybrid plants at the tetraploid and hexaploid levels, both for inter- and intra-specific fusions, charac­ters from sexually incompatible wild species are transferred to the cultivar.

Other approaches to genetic manipulation include the irradiation of donor protoplasts with useful characters, to frag­ment their genomes, followed by fusion to tetraploid acceptor protoplasts. Protoplast fusion also provides a means of transferring cytoplasmic traits into another genomic background.

Inter-generic somatic hybrids have been pro­duced in many genera like ‘Raphanobrassica’, obtained through fusion between Raphanus sativus and Brassica campestris, ‘Solanopersicon’, obtained through fusion between Solanum tuberosum and Lycopersicon esculentum, etc.

The technique of cybrid pro­duction has been utilized for transfer of cytoplas­mic male sterile character, as has been done in case of Nicotiana, Brassica and Petunia.

Application # 4. Production of Transgenic Plants:

Genetic engineering can be used to introduce genes into a plant, which do not exist in any member of the same plant family.

If genetically engineered plants are to be used commercially, then the following criteria are to be satisfied:

(a) Introduction of the gene(s) of interest to all plant cells

(b) Stable main­tenance of the new genetic information

(c) Trans­mission of the new gene to subsequent gene­rations

(d) Expression of the cloned genes in the correct cells at the correct time.

A number of useful traits, mostly single gene, that have been transferred to get the transgenic for various purposes are:

(i) Insect-pest resistance plants:

Using gene transfer technique the Bt. gene (Cry I protein from Bacillus thuringiensis) has been transferred to many crop plants like rice, cotton, tomato, pota­to, etc. and insect resistant plants (Bt. crops) have been developed.

(ii) Herbicide resistant plants:

Using biotechnological approaches many herbicide resistant crop plants have been obtained as in Brassica, tomato, corn, cotton, soya-bean, etc. which are resistant against glyphosate (Roundup), L-phosphinothricin (Basta), etc.

(iii) Virus resistant plants:

Viral coat protein genes can be introduced to get the virus resistant plants as has been done in tomato, potato, squash, papaya, etc.

(iv) Resistance against bacterial and fungal pathogens:

Several examples are available where the transgenic plants against bacterial and fungal pathogens have been developed. The chitinase gene have been introduced in tobacco to get the resistance against brown spot acetyl transferase gene has been introduced in tobacco to get the resistance against wild fire disease.

(v) Improvement in nutritional quality:

Nutritional quality can be improved by introduc­ing the genes for production of cyclodextrins, vita­mins, amino acids, etc.

Transgenic potato has been obtained to produce cyclodextrin molecule the transgenic rice named as ‘Golden rice’ has been obtained to produce pro vitamin-A which has opened the way for improving the nutritional stan­dards Ama-I gene has been introduced in potato. Starch content has been increased in transgenic potato.

(vi) Quality of seed-protein and seed-oil:

Recombinant DNA technology has been used successfully for improvement of protein quality in seed as has been done in pea plant which is rich in sulphur containing amino acids lysine rich cereals have also been produced.

Oilseed rape has been made transgenic which has the modified seed oil quality, i.e., low erucic acid. Reduced linolenic acid containing flax and high stearic acid containing soya-bean and safflower also have been produced.

(vii) Improvement of quality for food- processing:

‘Flavr-Savr’ variety of tomato has been raised which shows bruise resistance as well as delayed ripening.

(viii) Male sterility and fertility restoration in transgenic plants:

Male sterile transgenic plants have been produced with ‘barnase’ gene which has the cytotoxic product tagged with anther spe­cific TA-29 promoter, and another set of plants have been produced to restore the fertility factor with the help of ‘barstar’ gene tagged with the same promoter. F1 hybrids from these two sets of transgenic should facilitate the hybrid seed pro­duction for crop improvement.


Bacteria in Biology, Biotechnology and Medicine

Bacteria in Biology, Biotechnology and Medicine, Sixth Edition provides a readable, up-to-date introduction to the subject that assumes no prior knowledge. The most significant development since the publication of the Fifth Edition has been the publishing of the whole genome sequence, which will form the basis for the major changes to the sixth edition. Covering general bacterial physiology, the book starts with core aspects such as structure, growth, differentiation, metabolism, and molecular biology. It then looks at applied aspects including genetic engineering, medicine, food, biomining, water, and wastewater treatment. It also covers disinfection, sterilization, antibiotics, culture, microscopy, staining, and molecular taxonomy. Many up-to-date references to papers and reviews are included together with good clear illustrations and a comprehensive index.

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Bacteria in Biology, Biotechnology and Medicine, Sixth Edition is a broadly based textbook of pure and applied bacteriology. Written in clear language, the up-to-date text gives readers access to new ideas and developments in the current literature. The book is intended primarily for undergraduates and postgraduates in biology, biotechnology, medicine, veterinary science, pharmacology, microbiology, food science, environmental science and agriculture no prior knowledge of bacteria is assumed.

This new edition has been extensively updated much of the text is new, or re-written, and there are many new references. Over 70 genera of bacteria, listed alphabetically, are described in the Appendix. Cross-references and a detailed index, maximise the accessibility of data.

1. The bacteria: An introduction.

1.3 Classifying and naming bacteria.

2.1 Shapes, sizes and arrangements of bacterial cells.

2.2 The bacterial cell: A closer look.

2.3 Trichomes and coenocytic bacteria.

3. Growth and reproduction.

3.2 Growth in a single cell.

3.3 Growth in bacterial populations.

4.1 The life-cycle of Caulobacter.

4.4 Akinetes, heterocysts, hormogoni.

5.1 Energy metabolism in chemotrophs.

5.2 Energy metabolism in phototrophs.

5.3 Other topics in energy metabolism.

6 Metabolism II: carbon. 6.1 Carbon assimilation in autotrophs.

6.2 Carbon assimilation in heterotrophs.

6.3 Synthesis, interconversion and polymerization of carbon compounds.

6.4 Methylotrophy in bacteria.

7. Molecular biology I: genes and gene expression.

7.1 Chromosomes and plasmids.

7.2 Nucleic acids: Structure.

7.4 DNA modification and restriction.

7.5 RNA synthesis: Transcription.

7.6 Proteins: Synthesis and other aspects.

7.7 DNA monitoring and repair.

7.8 Regulation of gene expression.

8. Molecular biology II: changing the message.

8.5 Genetic engineering/recombinant DNA technology.

9.1 Virulent phages: The lytic cycle.

9.2 Temperate phages: Lysogeny.

9.6 How does phage DNA escape restriction in the host bacterium?

10. Bacteria in the living world.

10.1 Microbial communities.

10.2 Saprotrophs, predators, parasites, symbionts.

10.3 Bacteria and the cycles of matter.

10.4 Ice-nucleation bacteria.

10.5 Bacteriology in situ - fact or fiction?

10.6 The greenhouse effect.

10.7 Recombinant bacteria in the environment.

10.8 Uncultivable/uncultured bacteria.

11.1 Bacteria as pathogens.

11.2 The routes of infection.

11.5 The pathogen: Virulence factors.

11.6 Pathogen-host interactions: A new perspective.

11.7 The transmission of disease.

11.8 Laboratory detection and characterization of pathogens.

11.9 Prevention and control of transmissible diseases.

11.10 Some notes on chemotherapy.

11.11 Some bacterial diseases.

12. Applied bacteriology I: Food.

12.1 Bacteria in the food industry.

12.3 Food poisoning and food hygiene.

13. Applied bacteriology II: Miscellaneous aspects.

13.1 Feeding animals, protecting plants.

13.2 Biomining (bioleaching).

13.3 Biological washing powders.

13.6 Putting pathogens to work.

13.7 Plastics from bacteria: 'Biopol'.

13.9 Biomimetic technology.

14 Some practical bacteriology.

14.1 Safety in the laboratory.

14.2 Bacteriological media.

14.4 The tools of the bacteriologist.

14.5 Methods of inoculation.

14.6 Preparing a pure culture from a mixture of organisms.

16 The identification and classification of bacteria.

16.2 The classification (taxonomy) of prokaryotes.

Appendix Minidescriptions of some genera, families, orders and other categories of bacteria.


NCERT Solutions For Class 12 Biology Biotechnology and its Applications

Topics and Subtopics in NCERT Solutions for Class 12 Biology Chapter 12 Biotechnology and its Applications:

Section Name Topic Name
12 Biotechnology and its Applications
12.1 Biotechnological Applications in Agriculture
12.2 Biotechnological Applications in Medicine
12.3 Transgenic Animals
12.4 Ethical Issues
12.5 Summary

QUESTIONS FROM TEXTBOOK SOLVED

1. Crystals of Bt toxin produced by some bacteria do not kill the bacteria themselves because –
(a) bacteria are resistant to the toxin
(b) toxin is immature
(c) toxin is inactive
(d) bacteria encloses toxin in a special sac.
Ans: (c) Toxin is inactive.

2. What are transgenic bacteria? Illustrate using any one example.
Ans: Bacteria having gene or genes usually from an unrelated organism incorporated into their genome are called transgenic bacteria. For example, when human insulin gene is introduced into the isolated plasmid of E.coli bacterium and this recombinant DNA is transferred into a fresh bacterium, then the later is said to be transgenic or transformed bacterium.

3. Compare and contrast the advantages and disadvantages of production of genetically modified crops.
Ans:

4. What are Cry proteins? Name an organism that produces it. How has man exploited this protein to his benefit?
Ans: The bacterium Bacillus thuringiensis is a common soil bacterium which produces a protein toxin that kills certain insects. The toxin is a crystal (Cry) protein. There are several kinds of Cry proteins which are toxic to different groups of insects. The gene encoding Cry protein is called cry gene. Biotechnologists have been able to isolate the gene responsible for production of toxin and to introduce it into a number of plants to produce genetically modified plants resistant to insects, e.g., Bt cotton (resistant to bollworm) and GM tobacco (resistant to hornworms).

5. What is gene therapy? Illustrate using the example of adenosine deaminase (ADA) deficiency.
Ans: Gene therapy is correction of malfunctioning/gen by repairing or adding correct copy. ADA (adenosine deaminase deficiency) is a very rare genetic disorder due to deletion of the gene for adenosine deaminase. The enzyme is crucial for the immune system to functions. It can be treated by gene therapy. This gene is transfected into early embryonic cells of bone marrow for permanent use.

6. Digrammatically represent the experimental steps in cloning and expressing an human gene (say the gene for growth hormone) into a bacterium like E. coli?
Ans:

7. Can you suggest a method to remove oil (hydrocarbon) from seeds based on your understanding of rDNA technology and chemistry of oil?
Ans: The genes for the formation of oil in the seed should be identified. The appropriate genes should be removed with the help of restriction endonucleases. Such DNA should then be treated with DNA ligases to make seal DNA at the broken ends. These cells when grown aseptically on nutrient medium will differentiate into a new plant whose seeds will not have oil in them.

8. Find out from internet what is golden rice.
Ans: Golden rice is a transgenic variety of rice (Oryza sativa) containing good quantities of β-carotene (provitamin A) which is principle source of vitamin A. Since the grains of the rice are yellow in colour due to β-carotene, the rice is commonly called golden rice. It was developed at Swiss Federal Institute of Technology by Professor Ingo Potrykus and Peter Beyer.

9. Does our blood have proteases and nucleases?
Ans: No, blood does not have protease and nuclease. If it would have been there blood and cell would have been digested, some protease do exist in inactive form.

10. Consult internet and find out how to make orally activ&protein pharmaceutical. What is the major problem to be encountered?
Ans: Orally active protein product that is successfully manufactured is vaccines for preventions of infectious diseases such as hepatitis B, herpes, influenza, etc. Gene for antigen are isolated from bacteria and grown along with cut leaf portions of potato plant in antibiotic medium – followed by callus formation and recombinant/transgenic potato are obtained which contain those vaccines.


Applications of biotechnology in Agriculture

Shumbeyi Muzondo Correspondent
Biotechnology is biology’s fastest growing discipline prompted by the ever-increasing demand for food and fuel in a cleaner and greener environment.

In general, biotechnology encompasses a wide array of technologies that use living systems to produce useful products and services.

Integrating biotechnology into the agricultural system is critical to better use limited resources, increase agricultural yields and decrease the detrimental effects of using pesticides and chemical fertilisers.

Agricultural biotechnology is a field of agricultural science which uses cell and molecular biology tools to improve genetic makeup and agronomic management of crops and animals.

There are many biotechnology techniques employed by scientists and researchers in this discipline which include genetic engineering,marker assisted selection,hybridisation, plant tissue culture, biofertiliser technology, artificial insemination technology,plant and livestock disease diagnostics as well as vaccine production.

The use of these biotechnology tools in Zimbabwe has the potential to improve the livelihoods of about 7,6 million people living in the rural areas and depending mainly on agriculture.

Biotechnology being applied to a tomato plant

Recombinant DNA technology

This is a technology in which a plant or animal can receive genetic material (DNA) from a different organism to improve its attributes or make it perform new functions.

Genetically Modified Organisms (GMOs) include agricultural crops that have been genetically modified for resistance to pests, diseases or environmental conditions. For example Bt cotton is genetically modified cotton that incorporates a gene derived from a bacterium Bacillus thuriengiensis. Bt cotton is resistant to attack by the American bollworm, a major pest on cotton.

Other approaches may entail conferring to a plant resistance to chemical treatments (eg resistance to herbicides).

Alternatively the production of a specific nutrient or pharmaceutical product may be performed in a given GMO.

Despite having many benefits, GMO development encounters a number of obstacles including the high cost of creating one variety, the lengthy period to regulatory approval (usually 10 years at the least) and widespread public opposition.

Zimbabwe has not yet commercialised any GMOs.

Hybridisation involves combining the qualities of two organisms of different breeds, varieties, species or genera through sexual reproduction to impart a new character that would increase its yield. There are a number of companies in Zimbabwe which produce and distribute hybrid seeds including hybrid maize seed, cotton seed, wheat, soya bean, barley, sorghum and groundnut seed.

Biofertilisers are ready-to-use live formulations of beneficial micro-organisms. They are 100 percent organic and are applied to the seed, root or soil.

Biofertilisers can reduce the excessive use of chemical fertilisers, enrich the soil with those micro-organisms which produce organic nutrients for the soil and help combat diseases as well as provide the farmers with a cheaper source of fertiliser.

Marker assisted selection/ or molecular breeding

Marker assisted selection is a cutting-edge technology among today’s plant biotechnology companies. Plant breeders can use this technique to locate and assemble desirable traits to speed up the process of developing new commercial hybrids.

Unlike GMOs, new crop varieties produced by marker assisted selection are spared the regulatory trials and the public opposition mainly because the plant’s natural genetic boundaries are not crossed.

Some seed houses and research institutions in Zimbabwe have used this technique to develop improved crop varieties of maize, millet, sorghum and legumes that can withstand the adverse effects of climatic change.

The innovative solution to low yields for cassava, potato and sweet potato growers in Zimbabwe is tissue culture technology. Tissue culture, commonly referred to as micro-propagation, is a propagation tool where the cultivator grows tissue or cells outside of the plant itself in an artificial environment.

It can produce millions of disease-free plantlets from high yielding varieties. Instead of planting the cut pieces from the traditional matured plants or diseased seeds, farmers can plant virus-free and high vigour plantlets from high yielding varieties that are produced using tissue culture technology.

Harare Institute of Technology (HIT) is one of the institutions currently using tissue culture techniques to produce oyster mushroom spawn for commercial purposes. HIT has also extended its services by offering mushroom training courses.

Artificial insemination technology

Breeding technology has grown leaps and bounds over the last few decades with artificial insemination becoming one of the technologies adopted by many dairy and beef farmers for breeding the next generation of farm animals like cows and pigs.

Artificial insemination is the process of collecting sperm cells from a male animal and manually depositing them into the reproductive tract of a female. It offers the opportunity to use semen from the best bulls to build up carcass quality and weight gain in cattle.

Local farmers, with the assistance of a good breeder or knowledgeable inspector, can use this key tool to improve exports, wealth creation and nutrition for families.

Diseases Diagnostics and Vaccines

Farmers in Zimbabwe raise mainly cows, goats, chicken and sheep. Many diseases that reduce productivity for these farmers can be prevented by observing good hygiene, management and nutrition practices.

Biotechnology techniques for disease diagnostics and vaccine production are key tools for effective disease management.

These techniques compared to serological methods (blood tests that can diagnose various diseases) are performed faster, with a greater degree of accuracy, precision and reduced labour requirements.

Some local research institutes can develop vaccines and offer molecular diagnostic services for effective disease management which then translates to producing healthy livestock.

This presentation is but just a glimpse of the contributions of agricultural biotechnology to our society.

There are a lot more products and services on offer while some are still under development.

For further information please do not hesitate to contact the author at [email protected] or [email protected] Shumbeyi is a Lecturer in the Biotechnology department at the Harare Institute of Technology


Welcome to the Living World

- Products from non-human sources cause unwanted immunological responses. But recombinant therapeutics does not have such problems.

- At present, about 30 recombinant therapeutics have been approved. Of these, 12 are being marketed in India.

1. Genetically Engineered Insulin

- Insulin is used to manage adult-onset diabetes.

- Insulin from the pancreas of animals (cattle & pigs) causes allergy or other types of reactions to the foreign protein.

- Now, it is possible to produce human insulin using bacteria.

- Insulin consists of two short polypeptide chains (chain A & chain B) that are linked by disulphide bridges.

- In mammals, insulin is synthesized as a pro-hormone (pro-insulin). It is processed to become mature and functional hormone.

- The pro-hormone contains an extra stretch called C peptide. This is removed during maturation into insulin.

- In 1983, Eli Lilly (an American company) prepared two DNA sequences corresponding to A & B chains of human insulin and introduced them in plasmids of E. coli to produce insulin chains. Chains A & B were combined by creating disulfide bonds to form human insulin (Humulin).

- It is a method to correct a gene defect in a child/embryo.

- Here, genes are inserted into a person’s cells and tissues to treat a hereditary disease. It compensates for the non-functional gene.

- First clinical gene therapy (1990) was given to a 4-year old girl with adenosine deaminase (ADA) deficiency.

- This is caused due to the deletion of a gene of adenosine deaminase (an enzyme for the functioning of immune system). It can be cured by bone marrow transplantation or by enzyme replacement therapy (injection of ADA). But these are not completely curative.

- Gene therapy for ADA deficiency: Collect lymphocytes from the patient’s blood and grow in a culture → Introduce a functional ADA cDNA into lymphocytes (using a retroviral vector) → They are returned to the patient.

This should be periodically repeated as lymphocytes are not immortal.

- If the ADA gene from marrow cells is introduced into cells at early embryonic stages, it could be a permanent cure.

- Conventional methods ( serum & urine analysis) are not suitable for e arly diagnosis of diseases.

- It is possible by techniques such as Recombinant DNA technology, PCR & ELISA.

PCR (Polymerase Chain Reaction):

- Presence of a pathogen is normally suspected only based on symptoms. By this time, the concentration of pathogen is already very high in the body.

- However, very low concentration of a bacteria or virus can be detected by amplification of their nucleic acid by PCR.

o To detect HIV in suspected patients.

o To detect gene mutations in suspected cancer patients.

o To identify many other genetic disorders.

- A single stranded DNA or RNA, tagged with a radioactive molecule (probe) is hybridized to its complementary DNA in a clone of cells. It is detected by autoradiography. The clone having mutated gene will not appear on photographic film, because the probe will not have complementarity with mutated gene.

ELISA (Enzyme Linked Immuno-Sorbent Assay):

- It is based on antigen-antibody interaction.

- Infection by pathogen can be detected by the presence of antigens (proteins, glycoproteins, etc.) or by detecting the antibodies synthesized against the pathogen.


Biotechnology: what it is and how it's about to change our lives

Biotechnology - technology that uses living organisms to make products - could soon allow us to conjure up products as diverse as household cleaning products, organs for transplant and cleaner renewable fuels. Sang Yup Lee, Distinguished Professor at the Korea Advanced Institute of Science and Technology, and co-chair of the Global Future Council on Biotechnologies, explains how biotechnology is poised to change our lives, and why it could one day be as commonplace as having a cellphone or a tablet.

For people who are not familiar with biotechnologies, what are they and how do they impact our lives?

Biotechnology is a broad range of technologies that employ living organisms or parts of them to make diverse products. For example, drugs and therapeutics, nutritional compounds, environmentally friendly chemicals and materials, biofuels, and novel functional materials can be produced through biotechnology. More broadly, medical biotechnology, agricultural biotechnology and industrial biotechnology will all play increasingly important roles in our everyday life. Biotechnology can also be employed to degrade toxic or harmful chemicals and agents to solve environmental problems.

Your council will focus on developments in biotechnologies. What impact do you hope the council can have in the global conversation?

Like all technologies, biotechnology offers the potential of enormous benefit but also potential risks.

Biotechnology could help address many global problems, such as climate change, an aging society, food security, energy security and infectious diseases, to name just a few.

Our council intends to build a map of these global problems, which will show which biotechnologies could help with each global challenge. To do that, we will also take into consideration a realistic timeline, potential risks involved and other factors. Hopefully, the result will be a state-of-the-art biotechnology vision report that includes not only policy suggestions but also in depth information for both experts and the public.

What are these risks? What will the council do to avoid them?

Just like other emerging technologies, we cannot predict with absolute certainty the risks with biotechnology.

For example, synthetic biology is already contributing very much to the development of many biological systems producing drugs, chemicals and fuels without using fossil resources. However, if misused, synthetic biology can generate biological and chemical materials that are harmful to human beings as well as the environment.

Genome editing, especially when it is performed on people, will always carry ethical questions.

There are also questions in biofuels, ICT-based monitoring and diagnostics, and so on.

All these risks and challenges need to be addressed through dialogues among stakeholders including policy makers, experts, the public, and NGOs to map the risks and solutions. That is definitely one of the things The Global Future Council on Biotechnology will be studying by employing diverse expertise of council members and through dialogues with cross-council members and other stakeholders.

What else needs to be done to advance/speed up the development of bio-technologies? Where is it most relevant/important?

We need to see continued efforts in research as there are still many unknowns about living organisms. In depth research on cells, multi-cells, tissues, organs, organisms, and even communities of organisms would lead to better understanding of them and ultimately to develop better biotechnological applications.

Regulation is another place where we need to see advances. We need to ensure safety and security through regulation, but at the same time make sure we aren’t putting unnecessary hurdles in place which slow down progress. The only way we are going to achieve that is through a strong dialogue among all the stakeholders.

What are the big trends in biotechnologies right now? What are you excited about?

There are so many exciting things happening thanks to the rapid advances in biotechnology.

The genome editing of living organisms, including microorganisms, plants and animals, is exciting for many potential applications. With these advances, we could enhance bio-based chemicals production, increase food production and maintain a better nutritional value, or we could manufacture organs for transplant.

Metabolic engineering and synthetic biology are advancing very rapidly as well. That has led to the production of many chemicals, fuels and materials from renewable biomass, rather than depending on fossil resources.

We’re seeing some amazing developments in healthcare and the medical sector as well. New, highly complex natural compounds from bio-sources are becoming suitable for pharmaceutical purposes. Stem-cell therapy, ICT-integrated biotechnology, and many others will help address the health challenges brought on by an aging population.

Where do you think biotechnologies will be by 2030?

Biotechnology will become as common as having a cellphone or going online. There is going to be an even larger number of biotech companies, both big and small, along with an increasing number of venture companies.

In small villages or even at home, biotechnology might be used, just like in Science Fiction novels. You might simply ask a machine to make some household chemicals you need, rather than go buy it at the supermarket. Biotech trash converters could do away with waste.

Biotechnology could also help to tackle large national issues such as healthcare. Global healthcare spending, currently, is about 8 trillion US dollars. That price tag could be as high as we have to go, thanks to biotechnology. Even as the population grows, costs shouldn’t increase thanks to technologies such as efficient disease prevention and wellbeing programmes, precision medicine, genome editing, organ production, and stem-cell therapy. I think all of these will become rather routine.

So by 2030, I think it is realistic to say that biotechnology will become a part of our life, from drugs, medicine and therapeutics to environmentally friendly chemicals, fuels and materials.


The people

Exploring the lives and works of the leading people from across the world like Hubert Schoemaker (pictured) whose efforts have helped build biotechnology into a world changing science. Hubert Schoemaker (Born: 1950-03-23T00:00:00+0000 1950 - Died: 2006-01-01T00:00:00+0000 2006) Schoemaker was co-founder and first Chief Executive Officer of Centocor, an American biotechnology company that pioneered the commercialisation of monoclonal antibody diagnostics and therapeutics. Click here to learn more about Hubert Schoemaker.


The use of agricultural biotechnology

Genetic engineering

Over the years, researchers have learned how to mutate organisms, moving genes from one to another. This process is known as genetic modification, genetic improvement or genetic engineering. The process permits the transfer of useful characteristics into a microorganism, animal or plant by inserting genes from another organism. All the crops which have been improved using this process are meant to help farmers increase crop productivity. The process reduces crop damage from insects, diseases, and weeds.

Molecular diagnostics

These methods can help detect gene products or genes which are very precise. Molecular diagnostics are used in agriculture to diagnose livestock or crop diseases.

Molecular markers

Traditional breeding involves the selection of animals and plants relying on measurable or visible traits. Specialists are able to use molecular markers to select animals or plants which feature a desirable gene by analyzing the DNA of an organism. The process can be successful even in the absence of a visible trait. Therefore, breeding grew to be more efficient and precise. Molecular markers can also be used identify undesirable genes which can be eliminated in future generations.

Tissue culture

This is in charge of the plants’ regeneration in the laboratory when it comes to disease-free plant parts. The tissue culture technique allows for the reproduction of disease-free planting material for crops. Some examples of crops produced via tissue culture include papaya, coffee, bananas, mangoes, avocados, pineapples, and citrus.

Vaccines

The vaccines derived from biotechnology are implemented for humans and livestock. These vaccines can be better, cheaper and safer compared to traditional vaccines. They are stable at room temperature and will not need refrigerated storage. This is very important for smallholders in tropical countries. Some of these new vaccines can offer protection for the first time against some infectious illnesses.

The gene engineering process can make plants resistant to pests and insects.


Biotechnology in Medicine and Agriculture

It is easy to see how biotechnology can be used for medicinal purposes. Knowledge of the genetic makeup of our species, the genetic basis of heritable diseases, and the invention of technology to manipulate and fix mutant genes provides methods to treat diseases. Biotechnology in agriculture can enhance resistance to disease, pests, and environmental stress to improve both crop yield and quality.

Genetic Diagnosis and Gene Therapy

The process of testing for suspected genetic defects before administering treatment is called genetic diagnosis by genetic testing. In some cases in which a genetic disease is present in an individual’s family, family members may be advised to undergo genetic testing. For example, mutations in the BRCA genes may increase the likelihood of developing breast and ovarian cancers in women and some other cancers in women and men. A woman with breast cancer can be screened for these mutations. If one of the high-risk mutations is found, her female relatives may also wish to be screened for that particular mutation, or simply be more vigilant for the occurrence of cancers. Genetic testing is also offered for fetuses (or embryos with in vitro fertilization) to determine the presence or absence of disease-causing genes in families with specific debilitating diseases.

See how human DNA is extracted for uses such as genetic testing.

Gene therapy is a genetic engineering technique that may one day be used to cure certain genetic diseases. In its simplest form, it involves the introduction of a non-mutated gene at a random location in the genome to cure a disease by replacing a protein that may be absent in these individuals because of a genetic mutation. The non-mutated gene is usually introduced into diseased cells as part of a vector transmitted by a virus, such as an adenovirus, that can infect the host cell and deliver the foreign DNA into the genome of the targeted cell ([link]). To date, gene therapies have been primarily experimental procedures in humans. A few of these experimental treatments have been successful, but the methods may be important in the future as the factors limiting its success are resolved.

Production of Vaccines, Antibiotics, and Hormones

Traditional vaccination strategies use weakened or inactive forms of microorganisms or viruses to stimulate the immune system. Modern techniques use specific genes of microorganisms cloned into vectors and mass-produced in bacteria to make large quantities of specific substances to stimulate the immune system. The substance is then used as a vaccine. In some cases, such as the H1N1 flu vaccine, genes cloned from the virus have been used to combat the constantly changing strains of this virus.

Antibiotics kill bacteria and are naturally produced by microorganisms such as fungi penicillin is perhaps the most well-known example. Antibiotics are produced on a large scale by cultivating and manipulating fungal cells. The fungal cells have typically been genetically modified to improve the yields of the antibiotic compound.

Recombinant DNA technology was used to produce large-scale quantities of the human hormone insulin in E. coli as early as 1978. Previously, it was only possible to treat diabetes with pig insulin, which caused allergic reactions in many humans because of differences in the insulin molecule. In addition, human growth hormone (HGH) is used to treat growth disorders in children. The HGH gene was cloned from a cDNA (complementary DNA) library and inserted into E. coli cells by cloning it into a bacterial vector.

Transgenic Animals

Although several recombinant proteins used in medicine are successfully produced in bacteria, some proteins need a eukaryotic animal host for proper processing. For this reason, genes have been cloned and expressed in animals such as sheep, goats, chickens, and mice. Animals that have been modified to express recombinant DNA are called transgenic animals ([link]).

Several human proteins are expressed in the milk of transgenic sheep and goats. In one commercial example, the FDA has approved a blood anticoagulant protein that is produced in the milk of transgenic goats for use in humans. Mice have been used extensively for expressing and studying the effects of recombinant genes and mutations.

Transgenic Plants

Manipulating the DNA of plants (creating genetically modified organisms, or GMOs) has helped to create desirable traits such as disease resistance, herbicide, and pest resistance, better nutritional value, and better shelf life ([link]). Plants are the most important source of food for the human population. Farmers developed ways to select for plant varieties with desirable traits long before modern-day biotechnology practices were established.

Transgenic plants have received DNA from other species. Because they contain unique combinations of genes and are not restricted to the laboratory, transgenic plants and other GMOs are closely monitored by government agencies to ensure that they are fit for human consumption and do not endanger other plant and animal life. Because foreign genes can spread to other species in the environment, particularly in the pollen and seeds of plants, extensive testing is required to ensure ecological stability. Staples like corn, potatoes, and tomatoes were the first crop plants to be genetically engineered.

Transformation of Plants Using Agrobacterium tumefaciens

In plants, tumors caused by the bacterium Agrobacterium tumefaciens occur by transfer of DNA from the bacterium to the plant. The artificial introduction of DNA into plant cells is more challenging than in animal cells because of the thick plant cell wall. Researchers used the natural transfer of DNA from Agrobacterium to a plant host to introduce DNA fragments of their choice into plant hosts. In nature, the disease-causing A. tumefaciens have a set of plasmids that contain genes that integrate into the infected plant cell’s genome. Researchers manipulate the plasmids to carry the desired DNA fragment and insert it into the plant genome.

The Organic Insecticide Bacillus thuringiensis

Bacillus thuringiensis (Bt) is a bacterium that produces protein crystals that are toxic to many insect species that feed on plants. Insects that have eaten Bt toxin stop feeding on the plants within a few hours. After the toxin is activated in the intestines of the insects, death occurs within a couple of days. The crystal toxin genes have been cloned from the bacterium and introduced into plants, therefore allowing plants to produce their own crystal Bt toxin that acts against insects. Bt toxin is safe for the environment and non-toxic to mammals (including humans). As a result, it has been approved for use by organic farmers as a natural insecticide. There is some concern, however, that insects may evolve resistance to the Bt toxin in the same way that bacteria evolve resistance to antibiotics.

FlavrSavr Tomato

The first GM crop to be introduced into the market was the FlavrSavr Tomato produced in 1994. Molecular genetic technology was used to slow down the process of softening and rotting caused by fungal infections, which led to increased shelf life of the GM tomatoes. Additional genetic modification improved the flavor of this tomato. The FlavrSavr tomato did not successfully stay in the market because of problems maintaining and shipping the crop.

Section Summary

Genetic testing is performed to identify disease-causing genes, and can be used to benefit affected individuals and their relatives who have not developed disease symptoms yet. Gene therapy—by which functioning genes are incorporated into the genomes of individuals with a non-functioning mutant gene—has the potential to cure heritable diseases. Transgenic organisms possess DNA from a different species, usually generated by molecular cloning techniques. Vaccines, antibiotics, and hormones are examples of products obtained by recombinant DNA technology. Transgenic animals have been created for experimental purposes and some are used to produce some human proteins.

Genes are inserted into plants, using plasmids in the bacterium Agrobacterium tumefaciens, which infects plants. Transgenic plants have been created to improve the characteristics of crop plants—for example, by giving them insect resistance by inserting a gene for a bacterial toxin.

Multiple Choice

What is a genetically modified organism (GMO)?

  1. a plant with certain genes removed
  2. an organism with an artificially altered genome
  3. a hybrid organism
  4. any agricultural organism produced by breeding or biotechnology

What is the role of Agrobacterium tumefaciens in the production of transgenic plants?

  1. Genes from A. tumefaciens are inserted into plant DNA to give the plant different traits.
  2. Transgenic plants have been given resistance to the pest A. tumefaciens.
  3. A. tumefaciens is used as a vector to move genes into plant cells.
  4. Plant genes are incorporated into the genome of Agrobacterium tumefaciens.

Free Response

Today, it is possible for a diabetic patient to purchase human insulin from a pharmacist. What technology makes this possible and why is it a benefit over how things used to be?

The human insulin comes from the gene that produces insulin in humans, which has been spliced into a bacterial genome using recombinant DNA technology. The bacterium produces the insulin, which is then purified for human use. Before there was genetically engineered human insulin, diabetics were given insulin extracted from pig pancreases, which was similar to, but not exactly like, human insulin. Because it was not exactly like human insulin, the pig insulin caused complications in some diabetic patients.

Glossary


Watch the video: Laboratory of Bioorganic Chemistry and Pharmacognosy, Laboratory of Plant Biotechnology (May 2022).