Distribution of dorsal-forming activity in precleavage embryos of the Japanese newt, Cynops pyrrhogaster: effects of deletion of vegetal cytoplasm, UV irradiation, and lithium treatment.

Two types of axis-deficient embryos developed after deletion of the vegetal cytoplasm: wasp-shaped embryos and permanent-blastula-type embryos. In situ hybridization revealed that neither type of axis-deficient embryo expressed goosecoid or pax-6. brachyury was expressed in the constricted waist region of the wasp-shaped embryos but was not expressed in the permanent-blastula-type embryos. Further, we examined the effect of UV irradiation on Japanese newt embryos. Surprisingly, UV-irradiated Japanese newt eggs formed hyperdorsalized embryos. These embryos gastrulated in an irregular circular fashion with goosecoid expression in the circular equatorial region. At tailbud stage, these embryos formed a proboscis which is very reminiscent of that formed in hyperdorsalized Xenopus embryos. Transplantation of the marginal region of the UV-irradiated embryos revealed that the entire marginal zone had organizer activity. Thus we conclude that UV hyperdorsalizes Japanese newt embryos. Finally, lithium treatment of normal embryos at the 32-cell stage also resulted in hyperdorsalization. Lithium treatment of vegetally deleted embryos had two distinct results. Lithium treatment of permanent-blastula-type embryos did not result in the formation of dorsal axial structures, while the same treatment reinduced gastrulation and dorsal axis formation in the wasp-shaped embryos. Based on these results, we propose a model for early axis specification in Japanese newt embryos. The model presented here is fundamentally identical to the Xenopus model, with some important modifications. The vegetally located determinants required for dorsal development (dorsal determinants, DDs) are distributed over a wider region at fertilization in Japanese newt embryos than in Xenopus embryos. The marginal region of the Japanese newt embryo at the beginning of development overlaps with the field of the DDs. Gastrulation is very likely to be a dorsal marginal-specific property, while self-constriction is most probably a ventral marginal-specific property in Japanese newt embryos.

Malum perforans pedis caused by spinal canal stenosis and spondylolisthesis.

A case of malum perforans pedis caused by spinal canal stenosis with spondylolisthesis in a 76-year-old female is reported with a brief review of literature. In our case, orthopedic and neurological evaluations were indispensable for correct diagnosis and treatment of the condition.

Suppression of polar body formation by cytochalasin B and fusion of the resulting plural female pronuclei in eggs of the starfish, Asterina pectinifera.

In the starfish Asterina pectinifera, treatment of the eggs with cytochalasin B inhibits formation of the first or second polar body depending on when cytochalasin B is applied. Consequently, plural female nuclei are produced within the egg. These plural nuclei can fuse with each other after the egg is artificially activated with thymol. The further development of the eggs proceeds normally at least to the early blastula stage.