The study of the sea urchin embryo has contributed importantly to our ideas about embryogenesis. This essay re-examines some issues where the concerns of classical experimental embryology and cell and molecular biology converge. The sea urchin egg has an inherent animal-vegetal polarity. An egg fragment that contains both animal and vegetal material will produce a fairly normal larva. However, ...

Studies in fish and amphibia have shown that graded Bmp signalling activity regulates dorsal-to-ventral (DV) patterning of the gastrula embryo. In the ectoderm, it is thought that high levels of Bmp activity promote epidermal development ventrally, whereas secreted Bmp antagonists emanating from the organiser induce neural tissue dorsally. However, in zebrafish embryos, the domain of cells dest...

The initial effect of u.v. irradiation of the vegetal pole was to inhibit cleavage in the vegetal hemisphere although karyokinesis was not substantially affected. In this way a syncytium formed in the vegetal hemisphere which broke down into individual cells some time between morula and late blastula. The movement of the germ plasm from the peripheral cortical regions into the interior of the e...

BACKGROUND Vegetal BM 297 ATO is a food grade lipid based material extracted from vegetables, and certified for human consumption. In this study, Bifidobacterium longum LMG 13197 was encapsulated in Vegetal BM 297 ATO-inulin by freeze drying, followed by evaluation of its survival in simulated gastrointestinal fluids and yoghurt. Furthermore, the effect of incorporation of such microparticles o...

H E R B S T (1892) made the remarkable discovery that the differentiation of the sea-urchin egg was shifted in a vegetal direction when lithium ions were present in the sea-water. The vegetalization implies a failure of the apical tuft to appear, a displacement of the skeleton-forming cells in the animal direction, a reduction of the ectodermal region, and a corresponding enlargement of the end...

The egg of the frog Xenopus is cylindrically symmetrical about its animal-vegetal axis before fertilization. Midway through the first cell cycle, the yolky subcortical cytoplasm rotates 30 degrees relative to the cortex and plasma membrane, usually toward the side of the sperm entry point. Dorsal embryonic structures always develop on the side away from which the cytoplasm moves. Details of the...

The stability and movement of several polyadenylated (poly A+) and nonpolyadenylated (poly A-) mRNAs in Xenopus oocytes have been examined. At least 50% of the poly A+ mRNA molecules (9S rabbit globin mRNA, chicken ovalbumin, and lysozyme) were stable in oocytes over a 48-h period, irrespective of the amount injected. About 50% of injected poly A- reovirus mRNAs was degraded within the first 24...

Ablation of vegetal cytoplasm from newly fertilized Xenopus eggs results in the development of permanent blastula-type embryos (PBEs). PBEs cleave normally and develop into a very simple tissue consisting only of atypical epidermis. We tried to restore complete embryonic development in PBEs by cytoplasmic transplantation or by mRNA injection. We show a two-step reconstruction of the body plan. ...

Ablative techniques based on irreversible electroporation (IRE) have emerged as an effective cancer therapy. In these treatments electrical pulses are delivered in order to induce irrecoverable damage to the cell membranes, thus, causing cell death. An interesting feature of electroporation treatments is the capability to predict shape and extension of lesions by means of mathematical simulatio...

The Xenopus homologue of hARH (human autosomal recessive hypercholesterolemia) was identified in a screen for vegetally localized RNAs. xARH contains a N-terminal phosphotyrosine binding (PTB) domain that is 91% identical to that of the human gene, a domain previously shown to bind the LDL receptor family members. Maternal xARH, unlike hARH, is present as two transcripts that differ in their 3'...