Allozymes and isozymes


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Allozymes and isozymes

  1. 1. ALLOZYMES AND ISOZYMES Mohit Kumar Ram and Jitendra Kumar COF, Mangalore
  2. 2. OUTLINE  Introduction  Allozymes  Isozymes  Use of Allozymes & Isozymes  Significance of Allozymes & Isozymes study, in Ichthyotaxonomy  Allozyme electrophoresis  Advantages & disadvantages  Conclusion
  3. 3. Introduction  In Ichthyotaxonomy, DNA based molecular marker(Genetic Marker) plays an important role to identify the phylogenic trends of evolution  Now a days it is being replaced by various other methods of DNA-marker like, -Nuclear DNA markers(nDNA) -Mitochondrial DNA markers(mtDNA) -Restriction fragment length polymorphism (RFLP) etc.
  4. 4. Molecular Marker It is typical type of DNA sequence Used to mark a particular or specific location on the chromosomes It may also called genetic marker
  5. 5. Types of Molecular Marker  Allozyme markers  Nuclear DNA markers (nDNA)  Mitochondrial DNA markers (mtDNA)  Restriction fragment length polymorphism (RFLP)  Random amplified polymorphic DNA (RAPD)  Amplified fragment length polymorphism (AFLP)  Tandem repeated DNA (mini and microsatellites)  Single nucleotide polymorphism (SNP)  Expressed sequence tags (ESTs)
  6. 6. Basic functions of all markers  Genetic identification of aquaculture stocks  Identify the phylogenetic relationship between the different species of fishes  Monitoring of inbreeding or other changes in the genetic composition of the stocks  events and genetic drift  Comparisons between hatchery and wild stocks
  7. 7. Isoenzymes & Allozymes • Isoenzymes & Allozymes were first discovered by R.L.Hunter & Clement Markert in 1957 • Now days the two words i.e. Isoenzymes & Allozymes are usually used interchangeably • ExamplesLactate dehydrogenase (LDH) (chr-12) & (chr-15), malate dehydrogenes glucosephosphate, glucokinase etc.
  8. 8. Genetics A a A’ a’ Alleles Alleles A a A’ Gene-A a’ Gene-B
  9. 9. Allozyme  It represents the enzymes which is catalyzed by the different alleles of the same gene Allozyme
  10. 10. Isozyme/Isoenzyme • It represent the enzymes from different genes that process or catalyzed the same reaction • Differs in amino acid sequence E1 A + B E2 AB …..then E1 & E2 will be Isoenzymes
  11. 11. Functions of Allozymes in fisheries  To study the Genetic Variability of stock  To demonstrate Allozyme electrophoresis  To identify the genetic behavior of smolt age  To study the genetic characterization of the species and stock  To study the genetic drift of the species and stock  Genome mapping
  12. 12. Functions of Allozymes in Ichthyotaxonomy  Individual identification  Mixed Stock Fishery Analysis(MSFA)  To identify the phylogenetic relationship between the different species of fishes  To identify and arrangement of the species and stock on the basis of their genetic affinity  To identify the genetic diversity with in the stock & cultured species
  13. 13. Allozyme electrophoresis • Allozyme electrophoresis denotes technique for identifying genetic variation at the level of enzyme • Genetically different forms of an enzyme that are produced by different alleles at locus • Detected by electrophoresis • It is a Co-Dominant Mendelian characters
  14. 14. Electrophoresis Allozyme electrophoresis System
  15. 15. Protein Pattern after electrophoresis Protein Pattern after electrophoresis
  16. 16. Process of electrophoresis  Extraction , electrophoresis and observation of protein bands are the methods for detection of allozyme variation  Generally starch gel used for staining  40-50 individual can be analyzed per gel  Drawback of this is that only small fraction of enzyme loci
  17. 17. Advantages of Allozymes & Isoenzymes  Co dominant type markers  Easy to use  Easily adjustable from species to species  Low cost  General applicability
  18. 18. Disadvantages of Allozymes & Isoenzymes  Limited number of available Allozyme loci precludes their use in large-scale genome mapping  Heterozygote deficiencies due to null alleles  Reduce the level of detectable variation due to some changes in DNA sequence  Only a small fraction of enzyme loci appear to be allozymically polymorphic
  19. 19. CONCLUSION • Although, Isoenzyme & Allozyme are not used so much but yet it gives satisfactory result • It should apply to the genetics of phylogeny as it gives good result • It has limited use in fisheries sciences rather than other sciences
  20. 20. RFERENCES • ymes • mes • in fisheries • of isoenzymes and allozymes in fisheries • electrophoresis in fisheries
  21. 21. THANK YOU