Clonal domains in postlarval Platynereis dumerilii (Annelida: Polychaeta).

Following an enzymatic procedure for softening the egg envelope, blastomeres in the embryo of the polychaete Platynereis dumerilii were injected with TRITC-dextran. Injection was successful in the following blastomeres: AB, CD, A, B, C, D, 1a-1d, 1A-1D, 4d, and 4d(1). The distribution of fluorescent label was recorded by confocal laser scanning microscopy of young, three-segmented worms after 3 or 4 days of development, in some cases also in 1-day-old trochophore larvae.

The polychaete Platynereis dumerilii (Annelida): a laboratory animal with spiralian cleavage, lifelong segment proliferation and a mixed benthic/pelagic life cycle.

Platynereis dumerilii, a marine polychaetous annelid with indirect development, can be continuously bred in the laboratory. Here, we describe its spectacular reproduction and development and address a number of open research problems. Oogenesis is easily studied because the oocytes grow while floating in the coelom.

Vitellogenin from female and estradiol-stimulated male river lampreys (Lampetra fluviatilis L.).

The influence of estradiol-17beta (E(2)) on vitellogenesis is well documented for a number of oviparous craniates. We have examined the role that estradiol-17beta plays in the induction and regulation of vitellogenin synthesis in the maturing European river lamprey, Lampetra fluviatilis. In both females and males the estradiol-17beta concentrations in the plasma reached comparable maximum values in March, only a few weeks before spawning.

Molecular specification of cell lines in the embryo of Platynereis (Annelida).

In this study we describe the site and moment of histospecific differentiation in developmental stages of the annelid Platynereis dumerilii by use of biochemical markers. The monoclonal antibody (mab) OI7 and uncloned hybridoma supernatants (pAb's) OI8, OI10, OI46 and OI69 recognize neural antigens that appear asynchronously during development. By an enzymatic test, acetylcholinesterase (AChE) was found specific for nervous tissue as well.

A morphometric comparison of dissimilar early development in sibling species of Platynereis (Annelida, Polychaeta).

Early development of Platynereis massiliensis was studied in serial sections of fixed embryos and in living or fixed embryos whose nuclei had been made visible with a fluorescent label. The unfertilized egg is an ellipsoid with three axes of differing length. The longest axis corresponds to the dorsoventral axis of the developing embryo.

A correlative study of experimentally changed first cleavage and Janus development in the trunk of Platynereis dumerilii (Annelida, Polychaeta).

Among zygotes of Platynereis dumerilii treated with cytochalasin B (CCB) prior to first cleavage, a wide variety of developmental effects were observed. One effect is a delay in the first cleavage. Treated embryos may skip the first or even more than one cleavage cycle and become multinucleated.

[Action of theor-gene on pigmentation inPlatynereis dumerilii (Polychaeta) : II. Pigment deposition as caused by a maternal effect or immediately byor-gene activity].

1. A maternal Effect is observed in backcross progeny derived from heterozygous (+/or) females inPlatynereis: or/or-larvae from that cross resemble wildtype larvae with respect to the color of supporting cells as well as of iridophores (Fig. 4,3).

[Action of theor-gene on pigmentation inPlatynereis dumerilii (Polychaeta) : I. Time-course and sites of pigment deposition].

1. In theor-mutant ofPlatynereis dumerilii pigmentation is deficient in the iridophores and retinal supporting cells. The course of pigment deposition was examined in wildtype larvae (Figs.