Inducers Of Larval Metamorphosis Research Articles

Induction of reverse development in two marine Hydrozoans

Cnidarians are unique organisms in the animal kingdom because of their unequalled potential to undergo reverse development (RD). The life cycle of some species can temporarily shift ordinary, downstream development from zygote to adult into the opposite ontogenetic direction by back-transformation of some life stages. The potential for RD in cnidarians offers the possibility to investigate how integrative signalling networks operate to control directionality of ontogeny (reverse vs. normal development). Striking examples are found in some hydrozoans, where RD of medusa bud or liberated medusa stages leads to rejuvenation of the post-larval polyp stage. Artificial stress may determine ontogeny reversal. We describe here the results of experimental assays on artificial induction of RD by different chemical and physical inducers on two marine hydrozoans, Turritopsis dohrnii and Hydractinia carnea, showing a different potential for RD. A cascade of morphogenetic events occurs during RD by molecular mechanisms and cellular patterns recalling larval metamorphosis. For the first time, we show here that exposure to cesium chloride (CsCl), an inducer of larval metamorphosis, may also induce RD, highlighting similarities and differences between these two master ontogenetic processes in cnidarians.

Combination of macroalgae-conditioned water and periphytic diatom Navicula ramosissima as an inducer of larval metamorphosis in the sea urchins Anthocidaris crassispina and Pseudocentrotus depressus

The induction of larval metamorphosis in the sea urchins Anthocidaris crassispina and Pseudocentro(us depressus was investigated in the laboratory, using waters conditioned by 15 different macroalgae combined with the periphytic diatom Navicula ramosissima. Larvae of P. depressus did not metamorphose, but larvae of A. crassispina showed a high incidence of metamorphosis, especially in waters conditioned by coralline red algae or brown algae. High inductive activity for larval metamorphosis was detected in Corallina pi/ullfera-conditioned water during a 2.5-year investigation, but the activity was relatively low in February or March and in September, the off-growth seasons of the alga. By contrast, Ulva pertusa-conditioned water did not show metamorphosis-inducing activity except in spring or early summer. These results indicate that during their growth phase, red and brown algae release into their environment active substances that are involved in the larval metamorphosis of A. crassispina.

石灰藻ピリヒバ分泌液に含まれるムラサキウニ幼生の変態を誘起する活性物質の特性

Water conditioned by the coralline red alga Corallina pilulifera (C. pilulifera-conditioned water) in combination with the periphytic diatom Navicula ramosissima was found to induce metamorphosis in larvae of the sea urchin Anthocidaris crassispina. Bioassay-guided characterization of the active substances in C. pilulifera-conditioned water revealed that relatively heat-stable, non-volatile, polar substances are inducers of larval metamorphosis in A. crassispina. The molecular weights were estimated to be about 100 or less. Furthermore, fractionation by ODS column chromatography (0 to 100%, four gradients of MeOH) revealed that the activity was eluted mainly in the 0% and 70% fraction, although the activity was much lower than that of the control (C. pilulifera-conditioned water). When all four fractions (F1, F2, F3, and F4) were combined, the metamorphosis-inducing activity was recovered to almost the same level as that of the control. These results indicate that more than two metamorphosis-inducing substances may be present in C. pilulifera-conditioned water. Several authentic reagents such as phloroglucin and bromophenol did not show the metamorphosis-inducing activity even when combined with the diatom N. ramosissima.

Synthesis and absolute configuration of Stellettadine A: A marine alkaloid that induces larval metamorphosis in Ascidians

Stellettadine A, a bisguanidinium alkaloid isolated from a marine sponge Stelletta sp. as an inducer of larval metamorphosis in ascidians, and its unnatural enantiomer were synthesized from the enantiomers of citronellal. The absolute configuration of stellettadine A was established as R.

Inhibition of hatching in the ascidian, Halocynthia roretzi, by (Z)- and (E)-narains isolated from a marine sponge, Jaspis sp.

Summary (Z)- and (E)-narains, 3,4-dihydroxystyryl sulfates, have been isolated from a marine sponge Jaspis sp. as inducers of larval metamorphosis in the ascidian Halocynthia roretzi (Tsukamoto et al., 1994a, 1994b). Subsequently, we found that narains inhibited hatching in H. roretzi at concentrations of 10–50 μM, but did not affect trypsin-like protease activity which is released during larval hatching. Isolated chorion was dissolved by crude hatching enzyme solution and by commercially available trypsin from bovine pancreas. In both cases, dissolution of the chorion was inhibited by narains. Furthermore, the follicle cells surrounding the chorion of narain-treated embryos became condensed. These results suggest that narains do not inhibit hatching enzyme activity but rather affect the envelope of the embryo, resulting in inhibition of hatching.

ChemInform Abstract: Pipecolate Derivatives. Anthosamines A (Ia) and B (Ib), Inducers of Larval Metamorphosis in Ascidians, from a Marine Sponge Anthosigmella aff. raromicrosclera.

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Pipecolate derivatives, anthosamines A and B, inducers of larval metamorphosis in ascidians, from a marine sponge Anthosigmella aff. raromicrosclera

Anthosamines A and B ( 1 and 2), new pipecolate derivatives have been isolated as metamorphosis-inducers of ascidian Halocynthia roretzi larvae from a marine sponge Anthosigmella aff. raromicrosclera; along with a new diketopiperazine 3, cyclo-(L-Arg-dehydrotyrosine). Their structures were elucidated on the basis of spectral data. Reversible isomerization between amine and iminium ion forms were observed for 1 and 2; iminium ion forms ( 1b and 2b) predominate in protic solvent, amine forms ( 1a and 2a) in aprotic solvent.

3,4-Dihydroxystyrene dimers, inducers of larval metamorphosis in ascidians, from a marine sponge Jaspis sp.

Four new 3,4-dihydroxystyrene dimers ( 3, 4, 5, and 9) have been isolated from a marine sponge Jaspis sp. along with the known narains ( 1 and 2), of which 3– 5 induced metamorphosis of ascidian Halocynthia roretzi larvae. Structures of these metabolites were elucidated on the basis of spectral data. Biogenesis of these compounds is also discussed.