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Cytological changes and DNA and protein synthesis in parthenogenetically activated sea urchin eggs (1979)

Nakashima, Seiko ; Ishikawa, Masaru

Springer

Development genes and evolution 185 (1979), S. 323-332

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ISSN: 1432-041X

Keywords: Cytological change ; DNA and protein synthesis ; Parthenogenesis ; Sea urchin

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary The present study deals with cytological observations, DNA and protein synthesis in artificially activated sea urchin eggs. The eggs were activated by means of Loeb's double treatment with butyric acid and hypertonic sea water. Most of the eggs ofHemicentrotus pulcherrimus divided when the chromosomes duplicated after formation of the first monaster and other eggs divided at a later cell cycle. In the eggs ofTemnopleurus toreumaticus, however, haploid division at the first cell cycle was observed predominantly. Activated eggs that were treated for 25 min with hypertonic sea water showed a marked uptake of3H-thymidine during the two periods of 30–40 min and 90–100 min after the double treatment. These periodic changes in the3H-thymidine uptake paralleled morphological changes within the nucleus. However, these periods of increased uptake were not observed in the eggs treated with hypertonic sea water for 60 min. During exposure to hypertonic sea water, the3H-thymidine-uptake by eggs activated with butyric acid decreased gradually. When the uptake of14C-valine by eggs was measured, a very low level was seen in unfertilized eggs. The level of uptake increased strikingly when the eggs were activated with butyric acid but was suppressed by the hypertonic treatment. However, removal of the eggs to sea water allowed the uptake to return to the former high level. This pattern suggests that the hypertonic treatment has an inhibitory effect on the synthesis of protein (or enzymes) which obstruct cleavage induction.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00848519

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Electronic Resource

Cytological effects of urethan on cleavage induction in parthenogenetically activated sea urchin eggs (1979)

Nakashima, Seiko ; Ishikawa, Masaru

New York, NY : Wiley-Blackwell

Gamete Research 2 (1979), S. 213-222

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ISSN: 0148-7280

Keywords: urethan effect ; cleavage induction ; parthenogenesis ; sea urchin ; Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology

Notes: The effect of urethan on artificial induction of cleavage in eggs of the sea urchin, Hemicentrotus pulcherrimus, was studied. When the eggs were exposed for 20 minutes to seawater containing urethan (final concentration, 0.08 M) after butyric acid-activation and then treated with hypertonic seawater, the cleavage rate was enchanced by about 1.5 times as compared with the nontreated eggs. In the eggs exposed to urethan-seawater for over 70 minutes many clear spots appeared throughout the cytoplasm. Simultaneously, the pigment granules, which had been embedded within the cortex, migrated to the inner cytoplasm and encircled a monastral centrosphere and clear spots. The clear spots were composed of microtubules much like cytasters, and in the central region of them centrioles were not yet found. The eggs in which the pigment granules disappeared from the cortex may be more susceptible to cleavage induction by succeeding hypertonic treatment.

Additional Material: 6 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/mrd.1120020305

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