Relative Timing of Stiffening with Various Combinations of Nucleate and Enucleated Egg Fragments of Xenopus laevis. (egg stiffening/Xenopus laevis/cell cycle/timing system)

Cyclic cytoplasmic activity of non-nucleate egg fragments of Xenopus controls the morphology of injected sperms.

Triton X-100-treated sperms were injected into non-nucleate egg fragments of Xenopus laevis to determine whether the structure of the injected sperm nucleus is affected by the cyclic activity of the cytoplasm. Swollen vesicular nuclei were very frequently observed when the sperms were injected and incubated during the 'rounding-up' phase of the recipient fragment, whereas no such structures wer...

Preparation and Fractionation of Xenopus laevis Egg Extracts

Crude and fractionated Xenopus egg extracts can be used to provide ingredients for reconstituting cellular processes for morphological and biochemical analysis. Egg lysis and differential centrifugation are used to prepare the crude extract which in turn in used to prepare fractionated extracts and light membrane preparations.

A tribute to the Xenopus laevis oocyte and egg.

When I was asked to reflect as part of the celebration of the 100-year anniversary of the Journal of Biological Chemistry I recalled a talk by Seymour Cohen at the Federation meetings in Atlantic City about 1960. He began by thanking bacteriophage for providing him with so many wonderful research problems. I decided in the same spirit to pay homage to the Xenopus laevis egg and oocyte, two stat...

Cell-free apoptosis in Xenopus laevis egg extracts.

Hysteresis drives cell-cycle transitions in Xenopus laevis egg extracts.

Cells progressing through the cell cycle must commit irreversibly to mitosis without slipping back to interphase before properly segregating their chromosomes. A mathematical model of cell-cycle progression in cell-free egg extracts from frog predicts that irreversible transitions into and out of mitosis are driven by hysteresis in the molecular control system. Hysteresis refers to toggle-like ...