Hydra constitutively expresses transcripts involved in vertebrate neural differentiation.

The diploblastic Hydra is among the most primitive multicellular organisms. Using cross-hybridization with Xenopus probes, noggin-like transcripts were detected in the hypostome and basal disc of adult Hydra (Pelmatohydra oligactis), regions with properties similar to that of the amphibian organizer. This points to the possibility of a close molecular similarity between the Xenopus and Hydra organizers. The constitutive expression of a noggin-like gene in Hydra may be responsible for its regenerative capacity.

Ultrastructural cell surface alterations in developing embryos of frog (Microhyla ornata) treated with cytochalasins.

Scanning electron microscopic examination of M. ornata embryos treated with cytochalasins A, B and H (CA, CB and CH) showed extensive cell disaggregation resulting in large intercellular spaces and apparent loss of intercellular communication. All the three cytochalasins significantly reduced surface features, such as, filopodia and membrane ruffling which are considered essential for normal morphogenetic movements. Appreciable qualitative differences could not be detected in effects exerted by CA, CB and CH although potency of the three drugs clearly differed. The results demonstrate that in spite of the differences in their primary mechanisms of action, treatment with all the three cytochalasins culminates in comparable effects on the cell surface architecture resulting into abnormal morphogenesis.

Mesoderm enhancing effect of human seminal plasma inhibin and its synthetic C-terminal nonapeptide fragment in the chick embryo.

Isomers of fibroblast growth factor and members of the transforming growth factor beta family have been identified as potent mesoderm inducing factors, particularly in amphibians. Activins belonging to the latter group are capable of inducing all types of mesoderm. Inhibins, also belonging to the same family of proteins have an exactly opposite biological action than activins in the adult organism. We have examined the effects of human seminal plasma inhibin on the early development of the chick embryo, where also activins appear to be important in mesoderm induction. Contrary to expectations, inhibin brought about stimulation of development of somites and heart, structures of mesodermal origin, and increase in the body length in more than 50% of the treated chick blastoderms. A synthetic fragment of human seminal plasma inhibin, a nonapeptide fragment of C-terminal end, also exhibited similar effects. In some cases the treatments resulted in completely abnormal development while in some increase in the number of somites was associated with abnormality in the anterior region. Our results demonstrate that human seminal plasma inhibin does not act as an inhibitor of mesoderm induction in the chick embryo but in amniotes inhibin-related molecules may have a role as mesoderm enhancers.