BARKATULLAH UNIVERSITY BHOPAL M.P.

PRESENTATION TOPIC

HYBRIDIZATION IN FISHESPRESENTED BY :-

DEEVYA CHOUDHARYM.F.SC 4th SEMSUBMITTED TO

DEPARTMENT OF ZOOLOGY AND APPLIED AQUACULTURE

SYNOPSIS INTRODUCTION TYPES OF BREEDING ARTIFICIAL BREEDING NATURAL BREEDING DIPLOID HYBRID TRIPLOID HYBRID INTER GENERIC INTER SPECIFIC FISH ADVANTAGES &DISADVANTAGES OF

HYBRIDIZATION CONCLUSION

INTRODUCTIONHybridization is the act of breeding between two species /genera ,which ordinarily are not interbreeding.Most fish , however shed their gametes (egg and sperm) in water and fertilization is external . It is because of that fish hybridize more frequently than tetrapods. It is therefore not surprising that a natural hybridization is very common among fish, particularly among closely related families which share common habit and habitat requirements .Eg are numerous : Esocidac , Catatomidae, Cyprinidae , Salmonidac , Centrarchidae ,Poecillidae , Percidae are only some example out of 56 families Which are known for natural hybridization.It is well known that hybridization refers to cross-breeding between either members of different races or strains of the species (intra-specific);or between two species of the same genus (tnter-specific) and between species belonging to different genera (intergeneric ).Hybridization is usually aimed to combine positive traits of parent species in their hybrid offspring . The positive traits may include better growth , resistance to disease / changed environment , meat quality early or late maturity , better fecundity and so on.

HYBRIDIZ - TYPES

Hybridization natural or artificially induced ,results in an embryo which resembles neither one parent nor the other parent but posses characters which are intermediate between the characters possessed by the two parents . This embryo is called a hybrid . The hybrid may be diploid or triploid .

NATURAL BREEDING AND ARTIFICIAL BREEDING

Breeding behavior varies in fish from once in life time (0ncorhynchs) to once in a year (many major carps and most other fish) or monthly (lebistes) or continually throughout the year (cyprinus carpio) or once in ten to fourteen years (Anguilla).

For Indian major carps breeding is seasonal (once in a year) coinciding with rain and flood , which offer greatest opportunity for survival and development of the progeny.

EVENTS IN NATURAL BREEDING AND IN INDUCED BREEDING

ENVIROMENT STIMULI ↓ RECEPTORS ↓ BRAIN CENTERS ( hypothalamus) ↓ regulation Pituitary gland ↓ release pituitary extract (Gonadotropin hormone)

or Gonadotropin synthetic hormone / natural substitute Hormone ↓ ↓ gonad Gonad spawning breeding ↓ Spawning Natural breeding

Diploid hybrid

Cross between two different species result in diploid hybrid . Which are viable and so fin application in fish culture to the new combination traits both inter specific and intra generic hybrid have been achieved in India .

which attain maturity and are capable of producing in generation .

Triploid hybrid

The triploid hybrid by chromosomal maniculationWhich include the following .1. By inter generic mating between a diploid female of another of

one species and triploid male of another species .2. By subjecting the normally fertilized a involve in artificial in

sanitation off egg of one species by sperm of another species to head or cold .

3. By subjected the fertilized a involve in the egg one species with the sperm of another species to action of an antibiotic colchicum with are mitotic inhabitation . The triploid may viable but are sterile however the triploid growth faster than either diploid parent and so find use in fish culture in a monsoon mono sex culture system .

hybridization of two typesa. Inter specific hybridization b. Inter generic hybridization

INTERSPECIFIC HYBRIDIZATION

Interspecific reciprocal hybrids where produced among Indian major carp by crossing labeo rohita with labeo calbasu these hybrid have been son some traits of interest for aquaculture i.e hybrid exhibited faster growth the hybrid the slow growing parents the calbasu.For :- exampleMale female resultsLabeo rohita laboe calbasu rohu calbasuLabeo calbasu labeo rohita calbasu rohitaLabeo bata labeo rohita bata calbasuLabeo bata labeo calbasu bata calbasuLabeo calbasu labeo genius calbasu genius

INTER-GENERIC HYBRIDIZATION

Extensive work has been carried out on tnter-generic hybridization among the species or three genera i.e catla labeo and cirrihinus as many as 30 / . inter generic have been produced and evaluated for their positive traits how ever only few of then .these found to posses some positive characteristics which are useful for aquaculture.For:-exampleMale Female ResultsCatla catla Labeo rohita Catla rohitaCatla catla catla mrigala Catla mrigalaLaboe rohita catla mrigala Rohu mrigalaLaboe mrigala Laboe calbasu Mrigala calbasuCirrihinus rewa Labeo rohita Rewa rohu

Fluorescence In Situ Hybridization (FISH) A technique used to detect the presence or absence and

location of specific gene sequences-- chromosomal deletion, amplification, translocation.

Each fluorescently labeled probe that hybridizes to a cell nucleus in the tissue of interest will appear as a distinct fluorescent dot Diploid nuclei will have two dots If there is duplication in the region of interest, the gain will result in more than two dots. If there is a loss in the region of interest, one or zero dot will result

Schematic diagram for FISH technique

FISH: Advantages Can be used in formalin-fixed, paraffin embedded sections

or fresh frozen tissue Possible correlation between FISH result and tumor

morphology with conventional light microscopy Allows simultaneous interrogation of multiple cytogenetic

signatures Can be used either in bulky tumors or tumors where the

malignant component contributes to a small proportion of the overall cellular population

FISH: Limitations Probe design requires knowledge of specific chromosomal

abnormalities to be studied. Cutoff signals may be different among laboratories . Processing errors, imperfect hybridization, non-specific

binding, photobleaching, interobserver variability, and false positive and negative results are possible.

FISH: Summary FISH is a technique used to visualize specific cytogenetic

abnormalities It can serve as a supplementary diagnostic tool in

pigmented lesions. However, should not be used as a stand-alone test

Cannot replace traditional histopathologic analysis FISH result must correlated with clinical, pathologic and

molecular information.

ADVANTAGES &DISADVANTAGES OF HYBRIDIZATION

ADVANTAGES:-1. We get different types of animals(fish) and

organisms.2. Can get healthier animals(fish) and organisms DISADVANTAGES:-1. Some animal(fish)can become extinct2. Some animals(fish)could be prone to more

diseases.

CONCLUSIONHybridization is when two closely related fish

species, for example fishes come into contact and can mate successfully and reproduce. Hybridization creates problems for taxonomists ( the branch of science that is concerned with classification). Hybridization is a sign of continuous process of speciation or formation of new fishes.