Dataset Information

New insights into placozoan sexual reproduction and development.

ABSTRACT: Unraveling animal life cycles and embryonic development is basic to understanding animal biology and often sheds light on phylogenetic relationships. A key group for understanding the evolution of the Metazoa is the early branching phylum Placozoa, which has attracted rapidly increasing attention. Despite over a hundred years of placozoan research the life cycle of this enigmatic phylum remains unknown. Placozoa are a unique model system for which the nuclear genome was published before the basic biology (i.e. life cycle and development) has been unraveled. Four organismal studies have reported the development of oocytes and one genetic study has nourished the hypothesis of sexual reproduction in natural populations at least in the past. Here we report new observations on sexual reproduction and embryonic development in the Placozoa and support the hypothesis of current sexual reproduction. The regular observation of oocytes and expressed sperm markers provide support that placozoans reproduce sexually in the field. Using whole genome and EST sequences and additional cDNA cloning we identified five conserved sperm markers, characteristic for different stages in spermatogenesis. We also report details on the embryonic development up to a 128-cell stage and new ultrastructural features occurring during early development. These results suggest that sperm and oocyte generation and maturation occur in different placozoans and that clonal lineages reproduce bisexually in addition to the standard mode of vegetative reproduction. The sum of observations is best congruent with the hypothesis of a simple life cycle with an alternation of reproductive modes between bisexual and vegetative reproduction.

SUBMITTER: Eitel M

PROVIDER: S-EPMC3098260 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

New insights into placozoan sexual reproduction and development.

Eitel Michael M Guidi Loretta L Hadrys Heike H Balsamo Maria M Schierwater Bernd B

PloS one 20110519 5

Unraveling animal life cycles and embryonic development is basic to understanding animal biology and often sheds light on phylogenetic relationships. A key group for understanding the evolution of the Metazoa is the early branching phylum Placozoa, which has attracted rapidly increasing attention. Despite over a hundred years of placozoan research the life cycle of this enigmatic phylum remains unknown. Placozoa are a unique model system for which the nuclear genome was published before the basi ...[more]

PMID: 21625556

Similar Datasets

Project description:Phylogenetic relationships among mediophycean diatoms with elliptical valve outline and elevated apices have long been a subject of interest and debate, particularly with respect to their relationship to pennates. However, results remain inconclusive, whether based on vegetative valve morphology, reproduction, or molecular phylogenetic data. Searching for phylogenetically informative features, we re-examined sexual reproduction, auxospore structure and development in the diatom Biddulphia biddulphiana. Several unique or unusual features and processes characterized its sexual reproduction. A unique spermatogenesis occurs with premeiotic separation of an anucleate protoplast containing all chloroplasts and likely other organelles. Additionally, their auxospore walls are some of the most complex documented, retaining earlier deposited layers that obscure layers formed during later stages of development. The oldest layer consists of thick, mostly organic incunabulum, underlain by outer and inner epizonia and finally transverse (TP) and longitudinal (LP) perizonia. The complexity of the fine structure of these layers is unprecedented. The orientation of some TP bands is also unique in mediophytes, with some perpendicular to the auxospore apical axis, parallel to each other, and open with aligned ends, as typically seen in pennates. The TP also contains rings slanting toward the apices, as in some other mediophytes, e.g., eupodiscaceans. However, both eupodiscaceans and biddulphiaceans show perizonial band structure derived from anastomosing radial scales, thus termed "scaly bands". Pinnate TP bands, common among pennate auxospores, were not found. Thus B. biddulphiana auxospore wall structure contains a mixture of characters specific to this clone but also known from mediophytes and araphid pennates. However, these features do not provide unequivocal evidence that this or the other Biddulphia species examined to date are the closest extant relatives of basal araphid pennates.

Dataset Information

New insights into placozoan sexual reproduction and development.

Publications

New insights into placozoan sexual reproduction and development.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets