An electron-microscopic study of syncytium formation during early embryonic development of the freshwater planarian Bdellocephala brunnea

Sakurai, Takashige

doi:10.1007/978-94-011-2775-2_17

Cited by 2 publications

(2 citation statements)

References 11 publications

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“…A yolk gland is a reproductive organ filled with planarian nurse cells, namely yolk gland cells. Planarian eggs are called composite eggs (cocoons), which have several fertilized eggs and numerous yolk gland cells444546. Levels of a yolk gland marker gene, Dryg 47, were extremely high in fresh cocoons collected within a day of deposition (see Supplementary Fig.…”

Section: Discussionmentioning

confidence: 99%

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The identification of d-tryptophan as a bioactive substance for postembryonic ovarian development in the planarian Dugesia ryukyuensis

Kobayashi

Maezawa

Tanaka

et al. 2017

Sci Rep

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Many metazoans start germ cell development during embryogenesis, while some metazoans possessing pluripotent stem cells undergo postembryonic germ cell development. The latter reproduce asexually but develop germ cells from pluripotent stem cells or dormant primordial germ cells when they reproduce sexually. Sexual induction of the planarian Dugesia ryukyuensis is an important model for postembryonic germ cell development. In this experimental system, hermaphroditic reproductive organs are differentiated in presumptive gonadal regions by the administration of a crude extract from sexual planarians to asexual ones. However, the substances involved in the first event during postembryonic germ cell development, i.e., ovarian development, remain unknown. Here, we aimed to identify a bioactive compound associated with postembryonic ovarian development. Bioassay-guided fractionation identified ʟ-tryptophan (Trp) on the basis of electrospray ionization–mass spectrometry, circular dichroism, and nuclear magnetic resonance spectroscopy. Originally masked by a large amount of ʟ-Trp, ᴅ-Trp was detected by reverse-phase high-performance liquid chromatography. The ovary-inducing activity of ᴅ-Trp was 500 times more potent than that of ʟ-Trp. This is the first report describing a role for an intrinsic ᴅ-amino acid in postembryonic germ cell development. Our findings provide a novel insight into the mechanisms of germ cell development regulated by low-molecular weight bioactive compounds.

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Section: Discussionmentioning

confidence: 99%

“…This is one of the reasons the sexual worms contained much larger quantities of ᴅ- Trp than the asexual worms. Substances contained in yolk gland cells are used as nutrients for embryogenesis444546. Thus, the embryos may receive ᴅ- Trp.…”

Section: Discussionmentioning

confidence: 99%

The identification of d-tryptophan as a bioactive substance for postembryonic ovarian development in the planarian Dugesia ryukyuensis

Kobayashi

Maezawa

Tanaka

et al. 2017

Sci Rep

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Planarian embryology in the era of comparative developmental biology

Martín-Durán

Monjo²,

Romero

2012

Int. J. Dev. Biol.

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During the last decade, the field of evolutionary developmental biology (evo-devo) has emerged as a major research discipline in modern biology and an essential approach to understanding evolutionary relationships in the animal kingdom. At the same time, planarians have become a useful and important model with which to address basic questions regarding the molecular and cellular basis of regeneration, tissue repair and stem cells in adult organisms. Nevertheless, little attention has been paid to their embryonic development, even though this provides a unique opportunity for studying how molecular developmental mechanisms are redeployed during adult regeneration or the independent losses of spiral cleavage that took place in different lophotrochozoan lineages. In this paper, we review the most relevant works on planarian embryos from a historical point of view. In doing so, we highlight the questions that have recurrently intrigued researchers, most of which remain unanswered. Finally, we present a comprehensive scenario for planarian embryogenesis in an attempt to provide a testable hypothesis that will help to bridge the gap between this divergent mode of development, the ancestral canonical spiral cleavage, and adult planarian regeneration.

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An electron-microscopic study of syncytium formation during early embryonic development of the freshwater planarian Bdellocephala brunnea

Cited by 2 publications

References 11 publications

The identification of d-tryptophan as a bioactive substance for postembryonic ovarian development in the planarian Dugesia ryukyuensis

The identification of d-tryptophan as a bioactive substance for postembryonic ovarian development in the planarian Dugesia ryukyuensis

Planarian embryology in the era of comparative developmental biology

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