ERRATUM: GENE NUMBERS AND GENIC VARIABILITY IN CIONA INTESTINALIS AND BRANCHIOSTOMA LANCEOLATUM

1978 ◽  
Vol 20 (4) ◽  
pp. 600-600
Author(s):  
J. Schmidtke ◽  
B. Kunz ◽  
W. Engel
1978 ◽  
Vol 20 (1) ◽  
pp. 61-70 ◽  
Author(s):  
J. Schmidtke ◽  
B. Kunz ◽  
W. Engel

The number of genes coding for various enzymes have been determined in Ciona intestinalis (Tunicata) in comparison with Branchiostoma lanceolatum (Cephalochordata) using electrophoretic methods. Both species, generally, have identical gene numbers for homologous proteins. This finding does not support the hypothesis that Branchiostoma represents an anciently polyploid step relative to Ciona. High levels of allozymic variation were observed in the two species. The data are discussed in view of the neutral mutation hypothesis.


Author(s):  
N. J. Berrill

Ciona intestinalis (L.) is probably the most cosmopolitan species of ascidians and has long been of general interest. The adult morphology has been well described in monographic form by Roule (1884), the physiology of the heart and circulation by Heine (1902), Enriques (1904) and Wolf (1932), of the nervous system by Magnus (1902), Hecht (1918, 1926), Cate (1928), Haffner (1933), and Bacq & Florkin (1935), and of the digestive system by Yonge (1925). Developmental studies include that of the early embryology by Conklin (1905), problems of fertilization by Morgan (1945) and Damas (1899,1900). In no work, however, has there been a presentation of the entire Ciona organism from the tadpole stage through the critical post-larval stages to the young cionid ascidian. The present account portrays this period of development, together with a discussion of some significant but relatively obscure aspects of adult structure.Eggs and theRearing ofCiona intestinalisWhile ascidians in general are difficult to rear to maturity under laboratory conditions, Ciona is relatively easy, and together with Botryllus schlosseri (Pallas) and Diplosoma gelatinosum (M.-Edw.) is liable to appear more or less spontaneously in large aquaria into which tadpoles may have been brought. Artificial fertilization is readily accomplished, and at almost any time of the year, since Ciona is sexually mature above a certain size and reproduction is seasonal only to the extent of the rhythm of the growth cycle. Normally eggs are set free spontaneously at dawn, although individuals kept in the laboratory may accumulate eggs and the oviduct become swollen.


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