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Cyclic Changes in Shape of A Non‐Nucleate Egg Fragment of Tubifex (Annelida, Oligochaeta)
Author(s) -
SHIMIZU TAKASHI
Publication year - 1981
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1111/j.1440-169x.1981.00101.x
Subject(s) - cleavage (geology) , tubifex , biology , microfilament , anatomy , cycloheximide , cytoplasm , cytochalasin b , biophysics , oligochaeta (plant) , nucleus , crystallography , chemistry , microbiology and biotechnology , cell , zoology , biochemistry , ecology , protein biosynthesis , cytoskeleton , paleontology , fracture (geology)
A non‐nucleate fragment separated from the fertilized Tubifex egg at metaphase of the second meiosis showed temporary surface deformation at 3–3.5 hr intervals, i.e. , synchronously with the onset of formation of the second polar body and early cleavages in control eggs. From the two‐cell stage on, the periodicity of the surface activity in the non‐nucleate fragment was found to be synchronous with the cleavage cycles of the CD‐cell and its descendants, but not with those of the AB‐cell. This surface deformation was completely inhibited by cytochalasin B (50 μg/ml). Electron microscopy shows that microfilaments are present exclusively in the cortical layer of the deforming fragments. Cycloheximide‐treated egg fragments commenced surface deformation after a delay of 1–2 hrs; pulse‐treatment indicated that the surface deformation requires proteins synthesized specifically during the period of the previous surface deformation. These results are discussed in relation to the nucleus‐independent cytoplasmic rhythm and asynchronous cleavage of Tubifex eggs.