toxin is inactive:
In bacteria, the toxin is present in an inactive form, called prototoxin, which gets converted into active form when it enters the body of an insect.
Orally active protein pharmaceuticals contain biologically active materials such as peptides or proteins, antibodies, and polymeric beads. It is administrated orally into the body through various formulations. It involves the encapsulation of protein or peptide in liposomes or formulations using penetration enhancers. These proteins or peptides are used for treatment of various diseases and are also used as vaccines. However, the oral administration of these peptides or proteins has some problems related to it. Once these proteins are ingested, the proteases present in the stomach juices denature the protein. As a result, their effect will be nullified. Hence, it is necessary to protect the therapeutic protein from digestive enzymes, if taken orally. This is the reason for the proteins to be injected directly into the target site.How to make:
Transgenic bacteria contain foreign gene that is intentionally introduced into its genome. They are manipulated to express the desirable gene for the production of various commercially important products.
An example of transgenic bacteria is E.coli. In the plasmid of E.coli, the two DNA sequences corresponding to A and B chain of human insulin are inserted, so as to produce the respective human insulin chains. Hence, after the insertion of insulin gene into the bacterium, it becomes transgenic and starts producing chains of human insulin. Later on, these chains are extracted from E.coli and combined to form human insulin.
The production of genetically modified (GM) or transgenic plants has several advantages.
(i) Most of the GM crops have been developed for pest resistance, which increases the crop productivity and therefore, reduces the reliance on chemical pesticides.
(ii) Many varieties of GM food crops have been developed, which have enhanced nutritional quality. For example, golden rice is a transgenic variety in rice, which is rich in vitamin A.
(iii) These plants prevent the loss of fertility of soil by increasing the efficiency of mineral usage.
(iv) They are highly tolerant to unfavourable abiotic conditions.
(v) The use of GM crops decreases the post harvesting loss of crops.
However, there are certain controversies regarding the use of genetically modified crops around the world. The use of these crops can affect the native biodiversity in an area. For example, the use of Bt toxin to decrease the amount of pesticide is posing a threat for beneficial insect pollinators such as honey bee. If the gene expressed for Bt toxin gets expressed in the pollen, then the honey bee might be affected. As a result, the process of pollination by honey bees would be affected. Also, genetically modified crops are affecting human health. They supply allergens and certain antibiotic resistance markers in the body. Also, they can cause genetic pollution in the wild relatives of the crop plants. Hence, it is affecting our natural environment.
Cry proteins are encoded by cry genes. These proteins are toxins, which are produced by Bacillus thuringiensis bacteria. This bacterium contains these proteins in their inactive from. When the inactive toxin protein is ingested by the insect, it gets activated by the alkaline pH of the gut. This results in the lysis of epithelial cell and eventually the death of the insect. Therefore, man has exploited this protein to develop certain transgenic crops with insect resistance such as Bt cotton, Bt corn, etc.
Gene therapy is a technique for correcting a defective gene through gene manipulation. It involves the delivery of a normal gene into the individual to replace the defective gene, for example, the introduction of gene for adenosine deaminase (ADA) in ADA deficient individual. The adenosine deaminase enzyme is important for the normal functioning of the immune system. The individual suffering from this disorder can be cured by transplantation of bone marrow cells. The first step involves the extraction of lymphocyte from the patient’s bone marrow. Then, a functional gene for ADA is introduced into lymphocytes with the help of retrovirus. These treated lymphocytes containing ADA gene are then introduced into the patient’s bone marrow. Thus, the gene gets activated producing functional T- lymphocytes and activating the patient’s immune system.
DNA cloning is a method of producing multiple identical copies of specific template DNA. It involves the use of a vector to carry the specific foreign DNA fragment into the host cell. The mechanism of cloning and transfer of gene for growth hormone intoE.coli is represented below.
Recombinant DNA technology (rDNA) is a technique used for manipulating the genetic material of an organism to obtain the desired result. For example, this technology is used for removing oil from seeds. The constituents of oil are glycerol and fatty acids. Using rDNA, one can obtain oilless seeds by preventing the synthesis of either glycerol or fatty acids. This is done by removing the specific gene responsible for the synthesis.
Golden rice is a genetically modified variety of rice, Oryza sativa,which has been developedas a fortified food for areas where there is a shortage of dietary vitamin A. It contains a precursor of pro-vitamin A, called beta-carotene, which has been introduced into the rice through genetic engineering. The rice plant naturally produces beta-carotene pigment in its leaves. However, it is absent in the endosperm of the seed. This is because beta-carotene pigment helps in the process of photosynthesis while photosynthesis does not occur in endosperm. Since beta-carotene is a precursor of pro-vitamin A, it is introduced into the rice variety to fulfill the shortage of dietary vitamin A. It is simple and a less expensive alternative to vitamin supplements. However, this variety of rice has faced a significant opposition from environment activists. Therefore, they are still not available in market for human consumption.
No, human blood does not include the enzymes, nucleases and proteases. In human beings, blood serum contains different types of protease inhibitors, which protect the blood proteins from being broken down by the action of proteases. The enzyme, nucleases, catalyses the hydrolysis of nucleic acids that is absent in blood.
Adenosine deaminase deficiency is a metabolic disorder which causes immunodeficiency and damage to the immune system. It is caused by mutations in ADA gene. Approximately 10- 15 % of all cases of autosomal recessive forms of autosomal recessive forms of SCI among non- inbred population. SCID (Severe Combined Immuno Deficiency) disorder occurs due to adenosine deaminase deficiency. Adenosine deaminase catalyzes the conversion of adenosine to inosine, its deficiency results in accumulation of adenosine, and this interferes with purine metabolism that leads to the accumulation of nucleotides metabolites which are toxic to developing T- cell. This ADA deficiency can be present in infants, adolescence or in adults. It can be cured by bone marrow transplants (but by this deficiency cannot be permanently cured) or giving the approval of the germ line gene therapy which involves the permanent transmissible modifications of the genome of a gamete, a zygote or an embryo by this, deficiency can be permanently cured.
Recombinant DNA technology is a technique which enables the DNA to be identified, isolated and then recombined by which new features can be introduced into the organism. Specific tools that are used to accomplish the recombinant DNA technology with their functions are as follows:
Insulin is a polypeptide hormone that is used for saving the diabetic patients due to failure of insulin secretion in the pancreas or when the patient have low glucose level/ low blood sugar level then insulin injection is given and is composed of 51 amino acids arranged in two chains that are linked together by two disulfide bridges. It is produced by the β- cells of the islets of Langerhans and it favors the synthesis of glycogen, triacylglycerols and proteins. This acts to reduce the glucose concentration in the blood and thus stimulates the conversion of glucose to fats, proteins, ribulose 5- phosphate and glycogen etc.
Mature insulin is obtained by processing the pro- hormone that contains extra peptide known as C- peptide. Then, the C- peptide stretch of chain is removed during the conversion of prohormone to mature hormone (maturation process).
Gene therapy is a technique for correcting the defective genes responsible for disease development. It typically aims to supplement a defective mutant allele with a functional one. Several approaches have been given for correcting defective or abnormal genes like gene addition, gene replacement, and abnormal gene can be repaired through selective reverse mutation, which returns the gene to its normal function. And mainly it involves the germ line gene therapy which involves the permanent transmissible modifications of the genome of a gamete, a zygote or an embryo. Gene therapy is considered to be better option than enzyme replacement therapy because it has potential to for the complete cure of the gene defect.
Animals that have been permanently engineered by the gene insertion are known as transgenic animals and these contains functional foreign genes that have been introduced into the genome by genetic engineering. For example: First transgenic cow name was Rosie that contains cDNA which codes for the antibacterial human iron- binding protein called lactoferrin have been produced. In this cow, human genes are transferred that are expressed in mammary tissues and then the milk contains nutritionally more balanced product, α- lactalbumin for human bodies than natural cow milk. Transgenic animals are made to serve as the models for the human diseases like cancer, cystic fibrosis, Alzheimer etc. so that preventive measures are taken. For example: Transgenic Goats, they have human gene which codes for blood clot dissolving protein, i.e. Tissue plasminogen activator (TPA) is formed, secreted in milk. And, this is used for the treatment of coronary thrombosis disease.
Another example: in Canada, the gene for spider web has been isolated from the spiders and was inserted into a goat. The goat is producing spider web and the milk too. Due to this high tensile strength, these web fibers of the spiders now used for stitching the military uniforms, tennis and badminton rackets etc.
Foreign gene is usually ligated to the plasmid vector with the help of DNA Ligase enzyme and then introduced into the host cell. As when the plasmid replicates, this makes multiple copies of itself and thus foreign gene replicates and multiple copies are made. And when the host organism divides, its offspring receives the plasmid DNA contains the foreign gene.
Crop plants have been engineered to express the insecticidal toxin gene of Bacillus thuringiensis so that insects attempting to eat these plants get killed by producing insecticidal proteins called δ- endotoxin protein (cry proteins). Bt cotton does not harm other pests, it is only resistant to the specific pest. The genes that Bt cotton contains are pest specific. They are highly effective to the specific selective group of pest.
Note*: the gene for Bt toxin is expressed in pollen which might endanger pollinators like honeybees.
The patent was filed for the Basmati variety of Indian rice. Basmati is a variety of long grained aromatic rice which have been traditionally grown in India and this variety of rice have been cultivated in Indian subcontinents (have been cultivated all over the world) for the centuries. A USA Company has acquired the patent to claim the new variety of the Basmati rice.
Genetically Modified Organisms (plants, bacteria, fungi and animals) are ones that has its genetic material altered through any method (manipulation), including conventional breeding (development of new varieties of plants by using natural processes or older tools). They are usually formed by the alteration in gene is introduced in the organism and carried out in the in vitro condition. There are several advantages of genetically modified organisms and these are as follows:
Genetic manipulation of animal cells or animals that have been permanently engineered by the gene insertion are known as transgenic animals and these contains functional foreign genes that have been introduced into the genome by genetic engineering. In 1981, Ralph Brinster and Richard Palmiter introduced first transgenic animal, by introducing a gene for rat growth hormone (GH) into fertilized eggs of mice. Using, recombinant DNA technology any foreign gene that are added to the target organism are known as transgene, which leads to modification in the gene expressions. They can be utilized in the several ways:
Many plants can be regenerated from the single somatic cell grown in culture, in this genetic manipulation is performed, which produces new plant with the new traits, also known as transgenic plants. The unusual DNA vector for moving genes into the plant cells is a plasmid of the bacterium, Agrobacterium tumefaciens shows genetic transformation which involves the Agrobacterium and the host. It involves T- DNA and various virulence genes and every gene has their specific role in this process. The DNA segment of this plasmid that integrates into the chromosomal DNA of its plant host cell is known as T- DNA. This uptake of genes by microbial and plant cells is known as transformation. Main steps in genetic engineering of plants are given below:
Diagram representation of genetic engineering in plants:
Following are the five areas where biotechnology has influenced our lives are as follows:
Transgenic plants are produced easier than the engineered animals, single cell of the plants produces whole plant. Thus, a single genetically engineered cell can produce new plant with the useful modified characteristics. Some applications or areas where genetic modifications of plants have been useful are as follows:
Insulin controls the level of glucose in the blood, which is synthesized by the β- cells of the islets of Langerhans in the pancreas. Insulin deficiency manifests itself as diabetes mellitus shows complex of symptoms which may lead to death if untreated. Some disadvantages of insulin obtained from the pancreas of slaughtered cows and pigs are as follows:
Insulin is a polypeptide hormone that is used for saving the diabetic patients due to failure of insulin secretion in the pancreas or when the patient have low glucose level, then insulin injection is given and is composed of 51 amino acids arranged in two chains that are linked together by two disulfide bridges. It is produced by the β- cells of the islets of Langerhans and it favors the synthesis of glycogen, triacylglycerols and proteins. Then, mature insulin is obtained by processing the pro- hormone that contains extra peptide known as C- peptide. Then, the C- peptide stretch of chain is removed during the conversion of prohormone to mature hormone (maturation process). A number of human disorders that can be traced to the malfunction of the proteins that synthesized in the body which mainly can be treated by using the human proteins. But there are not many disorders can be treated with human or animal proteins, there is always the possibility of side effects like an allergic response. So, the production of recombinant pharmaceuticals occurred like recombinant insulin. There are some advantages of recombinant insulin which are as follows:
Bio- pesticides are the substances which are used to control the pest and are non- chemical in nature, safer for the environment than the chemical pesticides and fertilizers. A popularly known example is, Bacillus thuringiensis which is a bacterium that is pathogenic for the number of insect pests and Bt toxin is obtained from this. Its lethal effect is mediated by toxin that it produces. Through the recombinant DNA proteins methods, the toxin gene can be introduced directly into the genome of the plant where it is expressed and provide protection against the insect pest of the plant. In this, after ingestion of the proteins (inactivate proteins) by the insect, this protoxin cleaved by protease, results in the shorter version of proteins and shows toxicity/ acidity and due to presence of alkaline nature Bt toxin get activated by binding inside of the insect’s gut and damages the surface epithelium by creating pores which causes cells swelling and lysis; and hence the insect dies.