1.7.0 ADVANCE IN GENETICS
Laudable and landmark achievements has been made in the area of genetics. These achievements will be categorically grouped into the following areas;
a) Human Medicine.
1.7.1 Human Medicine :- the achievements are as follows;
i) The determination of genotype and phenotype of an individual.
ii) Determination on Human “DNA prints” for biological and criminal investigations.
iii) Detection of blood groups.
iv) Detection of some genetic diseases or abnormalities such as syndrome, congenital effects, blood disease (leukemia, anaemia, septicemia, etc.) diabetes, cancer, acquired immunodeficiency syndrome (AID) (caused by retrovirus )etc.
v) Fluorescence in situ hybridization (fish ) a technique used to identity the presence of specific chromosomes or chromosomal regions through hybridization (attachment ) of fluorescently labeled DNA probes . it provide researchers with a way to visualize and map the genetic material in an individual’s cells , including specific genes or portions of genes.
vi) Genetic research has provided geneticists or scientists with the best approach for controlling common diseases.
vii) Fluoresce in situ hybridization (fish) can be used to diagnose diseases like praden –will syndrome , Angelman syndrome, 22q 13 deletion syndrome, chronic myelogenous leukemia, acute lymphoblastic leukemia etc.
viii) Recombinant DNA technology is used in production of chemically active compounds such as hormones, grow factors, anti bodies, vaccines , anti biotics, interferons and thus gene therapy,
Research on plants has focused almost exclusively on a few of our most important agromonic crop. More recently, the potentials of genetic engineering of plants has been recognized and research activities have increased considerably. Plant systems represent a wealth of genetic diversity, and the increased research activities on plants should yield important information about the basic biology of different plant systems as well as some successful commercial applications of genetically engineered plants. Advances made in plant genetics are as follows;
i) Direct gene transfer, electroporation and microprojectile Guns= It involves the addition of selectable marker genes together with polyethylene glycol (which seems to stimulate membrane fusions)
ii) Herbicide –Tolerant plant s=when one spray plant (tomato Seeds) lightly with a solution containing a rapidly degradable broad- spectrum herbicide, the (tomato) plants carry a gene that makes them tolerant to the herbicide while all other plants (weeds) when present in tomato patch are killed by the herbicide.
iii) Disarmed Ti vectors = once it had been established that the T-DNA region of the Ti plasmid of Agrobacterium tumefaciensis is transferred to plant cells and becomes integrated in plant chromosomes, the potential use of A. tumefaciaens in plant genetic engineering was obvious. One could introduce foreign genes into the T-DNA region and hopefully, these genes would be transferred to the plant with the rest of the T- DNA segment.
iv) Disease and insect –Resistant varieties
One goal of plant genetic engineering is to transfer the genes encoding these protein toxins to agronomically important plants with the hope that expression of the toxin genes in these plants will provide biology control of at least some serious plant diseases and insect pests.
v) High-lysine corn.
Some cereal crops are deficient of some –essential amino acids. For example corn (the seed protein) is deficient of tryptophan and to a lesser extent of methionine and lysine . Mutants such as opaque-2 sugary -1, and floury-2 have increased amounts of lysine and/ or methionine in seeds.
Man relies on plants, animals and microorganism for his daily needs of food, clothing and health care. As a result of this, plant and animal breeders have strived to improve these organism. Methods of improvement have traditionally been by the conventional breeding techniques of selection and mating schemes aided at altering the genetic constitution of these organisms. More recently researchers have developed new techniques which have made it possible to manipulate the genome of living organism. These techniques, which belong to the realm of molecular biology, have resulted in the development of recombination DNA technology or genetic engineering. It is now possible, for example, to extract a DNA sequence or gene from one organism and insert it into another unrelated organism in a functional form. In agriculture, genetically engineered microorganism are being used to produce feed achieves, such as amino acids, vitamins and growth promoters. The greatest potential of this technology in agriculture is perhaps in the production of genetically engineered plants and animals with desirable characters, for example, incorporation of the growth hormone gene into the genome of domestic animals to improve their growth rate.
There are two processes involves in genetic manipulation of animals namely;
Identification and cloning of genes for desired traits, and insertion and regulation of expression of the genes.
(1) IDENTIFICATION AND CLONING = genetic engineering of domestic animals must be concerned with those characters that are controlled by single major genes, such as the B21 allele and dwarf gene in poultry, booroola in sheep, and halothane sensitivity gene in pigs. In order to achieve rapid progress in this respect, effort should be geared towards identifying various biochemical and physiological markers, including restriction fragment length polymorphisms (RELPS) in our domestic animals . These markers will surely facilitate the determination of specific sequence which will be exploited for cloning and subsequent transfer to recipients.
INSERTION AND REGULATION = cloned gene can be transferred to animal genomes either by micro-injection or by the use of DNA and RNA viruses as vectors. Domestic animals reproduce sexually by fusion of sperm and egg cells to form zygote. In order to achieve genetics transformation of these animal by genetic engineering, foreign DNA or gene must be inserted into the sperm, ovum or early embryo. Genetics in pisces (fish ) as vertebrate are not left behind. However huge level of progress has become recorded in the genetics of fish and this will form a major area of interest of these works.