Understanding Kappa Particles Transmission in Paramecium
Research by Dr. Shashikant R. Sitre delves into the transmission of kappa particles in Paramecium, revealing the presence of these cytoplasmic particles in specific strains. The interaction between killer and sensitive strains, controlled by the dominant K gene, sheds light on cytoplasmic heredity and the production of paramecin in Paramecium Aurelia. Through conjugation and cytoplasm exchange, the inheritance of kappa particles and the resulting traits are explored, highlighting the stable nature of this trait in killer strains.
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Kappa Particles Transmission in Paramoecium Dr.Shashikant R.Sitre Department of Zoology
Kappa Particles T.M.Sonneborn and his associates reported the transmission of certain cytoplasmic particles in paramecium Aurelia. These particles are called as kappa particles.
In this species two strains of individuals have been reported. One is killer which secretes a toxic substance paramecin and the other strain is known as sensistive and is killed if comes in contact with the paramecin.
In the cytoplasm of killer strain there are present the kappa particles which are particles of cytoplasmic deoxyribonucleic acid. Kappa particles are absent in sensitive strains.
The transmission of kappa particles is through cytoplasm but maintainance of kappa particles and production of paramecin is controlled by K gene which is dominant over a another k. The transmission of kappa particles and the killing effect can be traced out if there is conjugation between killer and sensitive strains. Normally there is no conjugation between these strains but by appropriate technique the two strains are mated to each other. The killer carry dominant allele KK and sensisitive kk.
On conjugation killer will produce killer daughters and sensitive sensitive daughters. But if the conjugation is for longer period ther will be exchange of cytoplasm resulting in the inheritance of kappa particles boy both the ex conjugants so that all the daughter paramecia produced are killer because all inherit the kappa particles through the mixing of cytoplasm. Therefore this trait is transmitted through cytoplasmic heredity. The trait is stable in killer stains.
Although the kappa particles are cytoplasmic particles and transmitted strictly through the cytoplasm, their maintainance and production of paramecin are controlled by a dominant gene K present in nucleus of killer strain. The sensitive stain possesses its recessive allele k.
By follwing an appropriate procedure it is possible to cross the individuals of killer and sensitive races. Observations on the descendents of such crosses have shown that individuals of killer clones carry a dominant gene k, whereas those of sensitive clones possess k. When killer KK conjugates with sensisitive kk, the exconjugants are Kk. These according to their genotype are killer.
In ordinary case of conjugation where only the nuclear material is exchanged and there is no exchange of cytoplasmic material, it has been found that each exconjugant gives rise to the organisms of its type ie,. Sensitive produces sensitives and killer produces killers. This suggests that killer character is not governed by gene.
In the second case when the conjugation is prolonged and cytoplasmic bridge between the conjugants is larger thatn usual, permitting exchange of
