Body Colors and Algal Distribution in the Acoel Flatworm Convolutriloba longifissura: Histology and Ultrastructure

Hirose, Euichi; Hirose, Mamiko

doi:10.2108/zsj.24.1241

Cited by 9 publications

(9 citation statements)

References 34 publications

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“…However, C. macropyga has both types of sagittocysts (Fig. 4c, d) and figure 11 in Hirose and Hirose (2007) shows a rectangular central filament in a sagittocyst in the body wall of C. longifissura . Using the most parsimonious explanation for the existence of round and rectangular central filaments in the genus Convolutriloba Hendelberg and Åkesson, 1988, and rectangular sagittocysts in all other sagittiferids, the rectangular shape is likely the original pattern, and the round filament, as well as the spiral muscle, would be derived.…”

Section: Resultsmentioning

confidence: 99%

Systematic revision of acoels with 9+0 sperm ultrastructure (Convolutida) and the influence of sexual conflict on morphology

Achatz

Hooge

Wållberg

et al. 2010

Journal of Zoological Systematics and Evolutionary Research

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We have used newly discerned morphological characters as well as molecular-sequence data from 18S and 28S rDNA to revise the families recently designated as the Ô9+0Õ acoels -what we call Convolutida. Characters from the ultrastructure of sperm, with their Ô9+0Õ axonemes, are useful in delineating the Convolutida, but are either species-specific or too conserved within the group to be used to infer relationships within it. Male genital organs, prostatoid organs, and sagittocysts, on the other hand, give a good phylogenetic signal for reconstructing relationships of such genera as Conaperta, Anaperus, and Achoerus; some features of the reproductive organs correlate with habitat and show how the Convolutida probably originated as epiphytic predators and radiated into the mesopsammon, pelagic, and coral-associated realms. In this revision of the Convolutida we provide revised synopses of its families -which we restrict to the Anaperidae, Convolutidae, and Sagittiferidae -and describe a new species, Polychoerus gordoni, from New Zealand. We transfer the genus Adenopea from the Antroposthiidae to the Convolutidae; Conaperta, Neochildia, and Oxyposthia from the Convolutidae to the Anaperidae; Paranaperus and Praeanaperus from the Anaperidae to the Haploposthiidae. Convoluta aegyptica is synonymized with Convoluta boehmigi, Convoluta lacazii with Convoluta sordida, and the genus Picola (Convolutidae) with Deuterogonaria (Haploposthiidae). Amphiscolops blumi, A. carvalhoi, and A. langerhansi, all of which possess a cellular seminal bursa, are transferred to the genus Heterochaerus. Convoluta elegans and Pseudanaperus tinctus are classified as nomina nuda. We use our findings on the ultrastructure of female genital organs and spermatozoa to show that sexual conflict plays a major role in the evolution of diversity of these structures and that the phylogeny of the Acoela would comprise early forms without female genital organs and hyper-or hypodermal transfer of sperm through advanced forms with ever longer and narrower bursal nozzles and sperm with axial microtubules. Moreover, our results show that the acquisition of endosymbiotic algae happened at least twice within the Acoela.

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Section: Resultsmentioning

confidence: 99%

Systematic revision of acoels with 9+0 sperm ultrastructure (Convolutida) and the influence of sexual conflict on morphology

Achatz

Hooge

Wållberg

et al. 2010

Journal of Zoological Systematics and Evolutionary Research

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show abstract

“…Also acoelomorph flatworms, whose phylogenetic placement is highly disputed [47], [48], [49], [50], have a totipotent stem cell system with comparable features [49], [51], [52]. It would therefore be interesting to study the formation process of the symbiont-housing cells in the acoels Symsagittifera roscoffensis (formerly Convoluta roscoffensis ) Graff 1891 [53], [54] or Convolutriloba longifissura Bartolomaeus & Balzer 1997 [55], [56].…”

Section: Discussionmentioning

confidence: 99%

Bacterial Symbiosis Maintenance in the Asexually Reproducing and Regenerating Flatworm Paracatenula galateia

et al. 2012

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Bacteriocytes set the stage for some of the most intimate interactions between animal and bacterial cells. In all bacteriocyte possessing systems studied so far, de novo formation of bacteriocytes occurs only once in the host development, at the time of symbiosis establishment. Here, we present the free-living symbiotic flatworm Paracatenula galateia and its intracellular, sulfur-oxidizing bacteria as a system with previously undescribed strategies of bacteriocyte formation and bacterial symbiont transmission. Using thymidine analogue S-phase labeling and immunohistochemistry, we show that all somatic cells in adult worms – including bacteriocytes – originate exclusively from aposymbiotic stem cells (neoblasts). The continued bacteriocyte formation from aposymbiotic stem cells in adult animals represents a previously undescribed strategy of symbiosis maintenance and makes P. galateia a unique system to study bacteriocyte differentiation and development. We also provide morphological and immunohistochemical evidence that P. galateia reproduces by asexual fragmentation and regeneration (paratomy) and, thereby, vertically transmits numerous symbiont-containing bacteriocytes to its asexual progeny. Our data support the earlier reported hypothesis that the symbiont population is subjected to reduced bottleneck effects. This would justify both the codiversification between Paracatenula hosts and their Candidatus Riegeria symbionts, and the slow evolutionary rates observed for several symbiont genes.

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“…For example, Convolutriloba longifissura harbors the prasinophyte alga Tetraselmis sp. (Hirose and Hirose, 2007); Waminoa acoels, which are epizoic on living corals, harbor two types of dinoflagellate symbionts: Symbiodinium sp. and Amphidinium sp.…”

Section: Mechanisms Of Maternal Inheritance Of Dinoflagellate Symbionmentioning

confidence: 99%

Mechanisms of Maternal Inheritance of Dinoflagellate Symbionts in the Acoelomorph WormWaminoa litus

Hikosaka-Katayama¹,

Koike²,

Yamashita³

et al. 2012

Zoological Science

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Waminoa litus is a zooxanthella-bearing acoel worm that infests corals. It is unique to Bilateria in that it transmits its algal symbionts vertically via eggs irrespective of the heterogeneity of the symbionts. It simultaneously harbors two dinoflagellate genera: Symbiodinium and Amphidinium. In this study, we examined the timing and vertical transmission pathway of algal symbionts in W. litus using light and electron microscopy. The oogenesis of the worm can be divided into three stages: stage I, in which the ovary is absent; stage II, the early vitellogenic zone containing immature oocytes formed in the ovary; and stage III, with both early and late vitellogenic zones in the body. In the early vitellogenic zone at stage II, oocytes are surrounded by accessory-follicle cells (AFCs). Both Symbiodinium and Amphidinium symbionts are not initially observed in the oocytes, but are observed in the AFCs. In the late vitellogenic zone at stage III, oocytes are enveloped by a complete sheath of AFCs; the algal symbionts are taken up by the late vitellogenic oocytes. These observations suggest that AFCs mediate the transfer of the algae from the parent to the oocytes. Ribotype analyses of the Symbiodinium symbionts revealed that they differ from those harbored by coral in the same experimental aquarium. These results indicate that W. litus has an active algal transport pathway and maintains a specific lineage of Symbiodinium via vertical transmission.

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Body Colors and Algal Distribution in the Acoel Flatworm Convolutriloba longifissura: Histology and Ultrastructure

Cited by 9 publications

References 34 publications

Systematic revision of acoels with 9+0 sperm ultrastructure (Convolutida) and the influence of sexual conflict on morphology

Systematic revision of acoels with 9+0 sperm ultrastructure (Convolutida) and the influence of sexual conflict on morphology

Bacterial Symbiosis Maintenance in the Asexually Reproducing and Regenerating Flatworm Paracatenula galateia

Mechanisms of Maternal Inheritance of Dinoflagellate Symbionts in the Acoelomorph WormWaminoa litus

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