Letter | Published:

Production of Abnormal Metamorphosis in a Tunicate

Naturevolume 175page1001 (1955) | Download Citation



IN this laboratory control hatchings of 95 per cent normal control tadpoles are regularly obtained from cross-fertilized eggs of Ciona intestinalis. The addition of phenylthiourea to the sea water in which they are developing produces a characteristic abnormality, which has been obtained regularly. A concentration of 0.001 per cent is effective, but not 0.0001 per cent. Apart from the interference with melanization of sensory vesicle structures, which is known in vertebrates1, this drug prevents the normal elongation of the notochord. Such tadpoles have short curved tails and do not swim. They remain unchanged after hatching for up to five days, when some attempt metamorphosis, which may be successful in the lower concentrations. Control tadpoles are usually 100 per cent attached and metamorphosing 24 hr. after hatching. When the monsters are placed in normal sea water on hatching, they remain unchanged except for melanization of the sensory vesicle. If, however, they are placed in 0.2 per cent phenylalanine in sea water, the tails are absorbed in 24 hr.; dihydroxyphenylalanine, thyroxine and tyrosine are loss effective, approximately in that order. Glycine and alanine do not have this action.

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  1. 1

    Millott, N., and Lynn, W. G., Quart. J. Micro. Sci., 95 (1), 17 (1954).

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  1. Department of Zoology, King's College, London, W.C.2.

    • L. G. E. BELL


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