Identification of jellyfish neuropeptides that act directly as oocyte maturation-inducing hormones.

Oocyte meiotic maturation is crucial for sexually reproducing animals, and its core cytoplasmic regulators are highly conserved between species. By contrast, the few known maturation-inducing hormones (MIHs) that act on oocytes to initiate this process are highly variable in their molecular nature. Using the hydrozoan jellyfish species and , which undergo oocyte maturation in response to dark-light and light-dark transitions, respectively, we deduced amidated tetrapeptide sequences from gonad transcriptome data and found that synthetic peptides could induce maturation of isolated oocytes at nanomolar concentrations.

Thrombospondin Type-1 Repeat Domain-Containing Proteins Are Strongly Expressed in the Head Region of Hydra.

The head region of Hydra, the hypostome, is a key body part for developmental control and the nervous system. We herein examined genes specifically expressed in the head region of Hydra oligactis using suppression subtractive hybridization (SSH) cloning. A total of 1414 subtracted clones were sequenced and found to be derived from at least 540 different genes by BLASTN analyses.

The nerve ring in cnidarians: its presence and structure in hydrozoan medusae.

In our previous studies of the Hydra nerve ring, we proposed the following hypothesis: "The nerve ring in the hypostome of Hydra is a central nervous system (CNS)-like neuronal structure." Related to this hypothesis, we have started to survey the nerve ring immunocytochemically using antibodies against neuropeptides throughout the whole phylum of cnidarians. In the present study, we describe nerve rings in hydrozoan medusae.

Inferences of evolutionary history of a widely distributed mangrove species, Bruguiera gymnorrhiza, in the Indo-West Pacific region.

Inference of genetic structure and demographic history is fundamental issue in evolutionary biology. We examined the levels and patterns of genetic variation of a widespread mangrove species in the Indo-West Pacific region, Bruguiera gymnorrhiza, using ten nuclear gene regions. Genetic variation of individual populations covering its distribution range was low, but as the entire species it was comparable to other plant species.