The genetic engineering. The bioethical aspects of genetic engineering

The genetic engineering has a widest application in practical field among all molecular genetics branches. The genetic engineering is a sum of methods of gene delivering from one organism to another; or it is a technology directed to new organism construction. The genetic engineering includes following operations: gene synthesis outside an organism, gene and genetic structures cleavage, directed gene recombination, obtained or newly synthesized gene coping and reproducing, such genes transport and insertion to genome subjected to modification, experimental composition of genes in one cell.

To give to an organism a new hereditary property we need to insert an appropriate gene (or group of genes) and to obtain functioning of this gene in particular cells. So we need to set it to regulatory system. The solving of this task may be divided into three stages: 1) obtaining genetic material (genes); 2) inserting genetic material to new organism; 3) setting of inserted genes to genetic cell apparatus and their fixation in it. Let’s look all these stages through.

The obtaining genetic material. The genetic material may be obtained by gene cleavage from donor cells or by its synthesis. We may get genes in chemical reactions or from rRNA using reverse transcriptase. Bacteria have genetic information stored in big circular DNA molecule and in small circular DNA fragments containing just several genes. These small fragments are called plasmids. The plasmids using gave a strong impact to a genetic engineering development. We may get a gene by different way, but commonly we use special enzymes such as restriction endonucleases and ligases. The restriction endonucleases are molecular “seizures” for fragment to be cut. The ligases are sealing enzymes. They can join cut strands back together. So may use these enzymes for DNA fragments elongation, DNA regions removing.

The inserting genetic material to new organism. We may use transformation, transduction, conjugation and somatic cells hybridization for this purpose.

The transformation (from Latin transformation - rebuilding) — is changing of hereditary material by income foreign DNA fragment. It is a one of genetic information exchange ways in prokaryotes. It was firstly observed by F. Griffit in 1928. In transformation, the inserted DNA fragments will be transmitted to all offsprings of next generations (pic 6.6).

Ріс. 6.6. The transformation of bacteria of ‘r’ culture to “S” cultureunder influence of DNA filtrate of “S” culture (by F. Kaudewitz, 1959)

The transduction (from Latin transduction - getting new localization) - is a way of transmitting of genetic material from one bacterial cell (donor) to another (recipient) by using moderate bacteriophag. It was discovered by J. Lederberg and N. Cinder in 19S2 while analyzing a changing in genetic material in some bacteria (shigells, salmonells etc.). When the prophag being induced, the small part of bacterial DNA incorporates to phag’s genome. Bacteriophag, carrying bacterial DNA, is called transducting phag. When new cell is infected by such phag, the DNA region inserts to cell genome. It is natural and wide spread between bacteria process of getting genetic recombination. That why it is widely used in genetic engineering of bacteria (pic 6.7).

Pic. 6.7. The bacterial transduction (Biological Science an inquiry into life, 1980)

The conjugation — is a process of genetic information exchange in bacteria during contact period. Information is transmitted from donor (“male” cell) to recipient (“female” cell). The conjugation is regulated by F-piasmids (fertility factors). One having F-plasmid is considered as donor. Another without it is considered as recipient. The size of exchanged material is determined by time of contact. As result of this, we have a cell with its own chromosome and with fragment of another one. This cell has a recombination of these genes. The cell from which material has been taken stays unchanged. Its genetic material is restored by DNA reduplication (pic 4.2).

The setting of inserted genes to genetic cell apparatus. The genes inserted to foreign cells cannot be reproduced. However, we may cope with this problem, if genes will be inserted to a structure, which has excellent apparatus of reproducing. Such structures are called vectors. It is a main device for all genetic manipulations. It is a structure, which is able to bring a foreign gene to a cell and to provide gene replication in anew cell.

Plasmids, bacteriaphages, viruses and cosmids are widely used as vectors. Cosmids are vectors obtained by bacteriophag and plasmid fragment fusing. Plasmids are vectors, which are independent from the main DNA molecule. They may be reproduced by themselves. We may get vectors with 3540 nucleotide length of insertion by using plasmids. Different viruses are used as vectors for animals and human.

The development of genetic engineering has facilitated in discovering many fundamental biological problems such as mosaic gene structure, decoding of gene structure, chemical gene synthesis and so on. The genetic engineering is a theoretical base for biotechnology. It is a directed production of necessary products and materials by using biological objects and processes. The biotechnology is used for microbiological producing of vaccines and serums; synthesis of hormones, vitamins, enzymes; diagnostics of human genetic defects on early stages of embryo development; genetic surgery (replacement of damaged gene by normal one) and so on.

The bioethical aspects of genetic engineering. In 1984, the European Committee of genetic engineering recommended to supervise all experiments of DNA recombination by genetic engineering council of state, where such experiments take place. Such recommendation was made for canceling experiments, which might be harmful for humankind or environment. Most of the experiments connected with human genetic material cloning mast to be prohibited. The works of chimeras and hybrids producing with help animal or human genetic material must to be banned. Only somatic cells may be used for therapeutic aims. The using of sex cells for genetic therapy will be possible, when advantages of such treatment over somatic cells genetic therapy will be proved.