serotaxonomy.pptx

Serotaxonomy gives a brief account of the techniques used for characterization of microorganisms based on antigen antibody reaction

1. S erotaxonomy M . Meenakshi , Sri Ramakrishna College of Arts & Science for Women, Coimbatore

2. SEROTAXONOMY Serology is defined as that portion of biology, which is concerned with the nature and interactions of antigenic material and antibodies . Systematic serology or serotaxonomy had its origin towards the end of twentieth century with the discovery of serological reactions and development of the discipline of immunology. Smith (1976) defined it as “the study of the origins and properties of antisera.” When foreign cells or particles (antigens) are introduced into an organism, antibodies are produced in the blood (antiserum). The substance capable of stimulating the formation of an antibody is called antigen and the highly specific protein molecule produced by plasma cells in the immune system in response to the antigen is called antibody.

3. PROCESS OF SEROTAXONOMY The process of serotaxonomy involves the following steps: The protein extract of the plant origin i.e. the antigen is extracted. The antigen is injected into the blood stream of an experimental animal to form antibodies. The experimental animal produces specific antibody in response to the antigen. The serum with antibodies is called antiserum. Antiserum is made to react in vitro with antigenic protein as well as proteins of other taxa, whose affinities are to be determined. The amount of precipitation shows the degree of homology. For example, to know the closeness of the taxon A with B, C, D, E

4. PROCESS OF SEROTAXONOMY The proteins from A are extracted and are injected into the experimental animal rabbit or mice. The experimental animal in return produces antibodies. These antibodies are extracted from the blood of the experimental animal in the form of antiserum. When this antiserum is allowed to react with the original protein extract from A, complete coagulation takes place. When this antiserum is allowed to react with the protein extracts from other taxa B, C, D, E the degree of coagulation varies. The degrees of coagulation are compared to know the closeness of the taxa. More the degree of coagulation more is the closeness.

5. METHODS USED IN SEROTAXONOMY: The crude protein extract of a particular plant taxa (antigen), is injected into the blood stream of an experimental animal, usually a rabbit or a rat, to develop antibodies. In response to the specific antigen injected, a specific antibody is produced in the blood of the animal. The serum (termed the antiserum) containing the antibody is then collected and made to react in vitro with the antigenic proteins as well as proteins from other related taxa, of which the affinities are in question.

6. SEROLOGICAL REACTIONS Serological reactions between antibodies and antigenic material results in the formation of a precipitate. This is called precipitin reaction. Kraus (1897) showed that this reaction indicates similarity of antigens. The degree of protein homology is determined by the amount of precipitation and hence is taken as a phylogenetic marker and taxonomic character . Each protein in turn carries a number of antigenic determinant sites (the portion of the antibody molecule that reacts with a portion of the antigenic material) or epitopes, each of which is capable of eliciting the production of distinct antibody molecules with a specific antibody determinant site or paratope , specific to that epitope.

7. IMMUNODIFFUSION IN AGAROSE GELS : In this method the antigen-antibody reaction is carried out in gels, mostly of agarose, in petridishes . The antiserum containing antibodies is filled in a well at the centre of the gel and the antigens from related taxa are placed in outer or radial wells. The antigen and antibody react to produce the insoluble antigen- antibody complex, forming a thin immobile band of precipitin (protein) at equilibrium, which can be visualized either directly or after protein staining for interpretation.

8. IMMUNODIFFUSION IN GELS CAN BE FURTHER OF TWO TYPES: Single radial immunodiffusion : In this technique, the antigen is usually allowed to diffuse into the gel containing the antiserum. Ouchterlony – double immunodiffusion : I n this method, both the antigen and antibody are allowed to diffuse into the gel and meet each other.

9. ROCKET IMMUNOELECTROPHORESIS: It is a simple, rapid and reliable method in which, rocket-like immunoprecipitate is formed when the desired protein (antigen) is electrophoresed in an agarose gel containing its mono-specific antiserum. A comparison of the height of the peaks of the unknown and standard samples also allows the unknown protein concentration to be determined.

10. A radioimmunoassay is an immunoassay that uses radiolabeled molecules in a stepwise formation of immune complexes. A RIA is a very sensitive in vitro assay technique used to measure concentrations of substances, usually measuring antigen concentrations by use of antibodies RADIOIMMUNOASSAY (RIA)

11. ENZYME-LINKED IMMUNOSORBANT ASSAY (ELISA) : ELISA  stands for enzyme-linked immunoassay. It is a commonly used laboratory  test  to detect antibodies in the blood. An antibody is a protein produced by the body's immune system when it detects harmful substances, called antigens The assay uses a solid-phase type of  enzyme immunoassay  (EIA) to detect the presence of a  ligand  (commonly a protein) in a liquid sample using antibodies directed against the protein to be measured. 96 well microtitre plate

12. ENZYME-LINKED IMMUNOSORBANT ASSAY (ELISA) : This method is generally used for quantitative estimation of a particular protein in a mixture, but can also be used to study the antigen-antibody reaction. The antibodies against a particular antigen are adsorbed to a solid support, in most cases a polystyrene microtiter plate . The support after coating with antibody is washed and then the antigen is added, which binds to the adsorbed antibodies . An enzyme-linked antibody molecule called the conjugate is then added, which also binds to the antigen, which is followed by a chromogenic substrate for the enzyme.

13. ENZYME-LINKED IMMUNOSORBANT ASSAY (ELISA) : The colored product generated is observed for confirmation of antigen-antibody reaction as well as measured for quantitative estimation. The intensity of the color is proportional to the bound enzyme and thus to the amount of the bound antigen . ELISA has been used as a  diagnostic  tool in medicine,  plant pathology , and  biotechnology , as well as a  quality control  check in various industries

14. IMPORTANCE OF SEROTAXONOMY It determines the degree of similarity between species, genera, families etc. by comparing the reactions of antigens from various plant taxa with antibodies raised against the antigen of a given taxon.

15. REFERENCES https://www.learninsta.com/modern-trends-in-taxonomy/ https://www.biologydiscussion.com/plant-taxonomy/serotaxonomy-definition-history-and-roles-plant-taxonomy/30466