allozymes and isozymes

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Mohit Kumar Ram and Jitendra Kumar

COF, Mangalore

ALLOZYMES AND ISOZYMES

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OUTLINE Introduction

Allozymes

Isozymes

Use of Allozymes & Isozymes

Significance of Allozymes & Isozymes study, in Ichthyotaxonomy

Allozyme electrophoresis

Advantages & disadvantages

Conclusion

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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.

Introduction

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It is typical type of DNA sequence

Used to mark a particular or specific location on the chromosomes

It may also called genetic marker

Molecular Marker

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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)

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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

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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

• Examples-

Lactate dehydrogenase (LDH) (chr-12) & (chr-15), malate dehydrogenes glucosephosphate, glucokinase etc.

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Genetics

Alleles

Alleles

Gene-A Gene-B

A

A

a

a

A’

A’

a’

a’

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Allozyme It represents the enzymes which is catalyzed by the

different alleles of the same gene

Allozyme

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Isozyme/Isoenzyme

• It represent the enzymes from different genes that process or catalyzed the same reaction

• Differs in amino acid sequence

…..then E1 & E2 will be Isoenzymes

E1E2

A + B AB

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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

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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

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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

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Electrophoresis

Allozyme electrophoresis System

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Protein Pattern after electrophoresis

Protein Pattern after electrophoresis

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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

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Advantages of Allozymes & Isoenzymes

Co dominant type markers

Easy to use

Easily adjustable from species to species

Low cost

General applicability

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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

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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

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RFERENCES

• www.google.com/www.wikipedia.com/isoenzymes

• www.google.com/www.wikipedia.com/allozymes

• www.google.com/pdf/file/genetics in fisheries• www.google.com/pdf/file/application of

isoenzymes and allozymes in fisheries• www.google.com/pdf/file/allozyme

electrophoresis in fisheries

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THANK YOU