The authors have previously found that mutant hydra strains showing various types of developmental defects can be isolated through sexual inbreeding of wild hydra. One such defective strain, called nem-4, contains virtually no stenoteles, one of the four types of nematocysts present in hydra, in its tentacles. However, stenoteles are present at a normal level in the body column of this strain, ...

We describe here the Drosophila gene hydra that appears to have originated de novo in the melanogaster subgroup and subsequently evolved in both structure and expression level in Drosophila melanogaster and its sibling species. D. melanogaster hydra encodes a predicted protein of approximately 300 amino acids with no apparent similarity to any previously known proteins. The syntenic region flan...

Hydra, one of the earliest metazoans with tissue grade organization and nervous system, is an animal with a remarkable regeneration capacity and shows no signs of organismal aging. We have for the first time identified genes of the nucleotide excision repair (NER) pathway from hydra. Here we report cloning and characterization of hydra homolog of xeroderma pigmentosum group F (XPF) gene that en...

Small non-coding RNAs such as miRNAs, piRNAs and endo-siRNAs fine-tune gene expression through post-transcriptional regulation, modulating important processes in development, differentiation, homeostasis and regeneration. Using deep sequencing, we have profiled small non-coding RNAs in Hydra magnipapillata and investigated changes in small RNA expression pattern during head regeneration. Our re...

Senescence, a deteriorative process that increases the probability of death of an organism with increasing chronological age, has been found in all metazoans where careful studies have been carried out. There has been much controversy, however, about the potential immortality of hydra, a solitary freshwater member of the phylum Cnidaria, one of the earliest diverging metazoan groups. Researcher...

Existing data imply that the cnidarian Hydra vulgaris does not undergo senescence. In contrast, the related species Hydra oligactis shows increased mortality and physiological deterioration following sexual reproduction. Hydra thus offers the chance to study a striking difference in lifespan in members of the same genus. Adult Hydra possess three well-characterized stem cell populations, one of...

The freshwater polyp Hydra is the most frequently used model for the study of development in cnidarians. Recently we isolated four novel Arg-Phe-NH2 (RFamide) neuropeptides, the Hydra-RFamides I-IV, from Hydra magnipapillata. Here we describe the molecular cloning of three different preprohormones from H. magnipapillata, each of which gives rise to a variety of RFamide neuropeptides. Preprohorm...

Hydra formulas were introduced in (Sloan, Stasi, and Turán 2012). A hydra formula is a Horn formula consisting of definite Horn clauses of size 3 specified by a set of bodies of size 2, and containing clauses formed by these bodies and all possible heads. A hydra formula can be specified by the undirected graph formed by the bodies occurring in the formula. The minimal formula size for hydras i...

Hydra's remarkable capacity to regenerate, to proliferate asexually by budding, and to form a pattern de novo from aggregates allows studying complex cellular and molecular processes typical for embryonic development. The underlying assumption is that patterning in adult hydra tissue relies on factors and genes which are active also during early embryogenesis. Previously, we reported that in Hy...

In hydra all cell-cycle control occurs in the G2/M transition. Cyclins acting at this restriction point in the cell cycle belong to the cyclin A and B families. In agreement with this we isolated cDNAs coding for a cyclin A and a cyclin B from the multiheaded mutant of Chlorohydra viridissima and a cyclin B from Hydra vulgaris. The two B-type cyclins from hydra show 85.6% identity at the amino ...