Kinetid structure in sponge choanocytes of Spongillida in the light of evolutionary relationships within Demospongiae

Pozdnyakov, Igor R.; Sokolova, Agniya M.; Ereskovsky, Alexander; Karpov, Sergey A.

doi:10.1093/zoolinnean/zlx109

Cited by 10 publications

(18 citation statements)

References 37 publications

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“…The choanocyte kinetids of Oscarella lobularis and O. balibaloi closely resemble the kinetids of previously studied sponge species (Pozdnyakov, & Karpov, 2013, 2016a, 2016bPozdnyakov et al, 2017;Pozdnyakov, Sokolova, Ereskovsky, & Karpov, 2018). Their choanocytes have apical nuclei connected to the kinetosomes with fibrillar roots.…”

Section: Discussionsupporting

confidence: 71%

Morphological variability of choanocyte kinetids supports a novel systematic division within Oscarellidae (Porifera, Homoscleromorpha)

Pozdnyakov

Agniya

Sergey

et al. 2020

J. Zool. Syst. Evol. Res.

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Homoscleromorpha is a recently recognized class within the phylum Porifera. While molecular analyses support monophyly of Homoscleromorpha, morphological data are largely lacking. Here, we investigate and comparatively analyze the detailed morphology of kinetids (flagellar apparatus) in choanocytes of ten Oscarella species. The kinetid is known to be a phylogenetically important trait that can possibly reflect relationships of sponges at the level of orders. We also conduct a phylogenetic analysis based on previously published sequences. We found the family Oscarellidae is subdivided into two large groups, and choanocyte kinetids structure strongly supports this division. The first group includes Oscarella lobularis, O. tuberculata, O. bergenensis,

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Section: Discussionsupporting

confidence: 71%

Morphological variability of choanocyte kinetids supports a novel systematic division within Oscarellidae (Porifera, Homoscleromorpha)

Pozdnyakov

Agniya

Sergey

et al. 2020

J. Zool. Syst. Evol. Res.

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“…There are, however, some basic differences between sponges and choanoflagellates in how their collar and flagella interact, suggesting that choanocyte/choanoflagellate similarity might be superficial and that specific homology cannot be automatically assumed (see [71] for details). Indeed, recent ultrastructural studies on sponge choanocytes and choanoflagellates show that they are fundamentally different in many respects (see [72][73][74] for details), some of which are among the very few ultrastructural systems in eukaryotic cells considered sufficiently conservative to indicate phylogenetic relationships [75][76][77]. For example, specific features of the flagellar apparatus of the sponge Ephydatia fluviatilis are more similar to zoospores of chytrids than to choanoflagellates [78].…”

Section: Origins Of Multicellularitymentioning

confidence: 99%

Insights into the origin of metazoan multicellularity from predatory unicellular relatives of animals

et al. 2020

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Background: The origin of animals from their unicellular ancestor was one of the most important events in evolutionary history, but the nature and the order of events leading up to the emergence of multicellular animals are still highly uncertain. The diversity and biology of unicellular relatives of animals have strongly informed our understanding of the transition from single-celled organisms to the multicellular Metazoa. Here, we analyze the cellular structures and complex life cycles of the novel unicellular holozoans Pigoraptor and Syssomonas (Opisthokonta), and their implications for the origin of animals. Results: Syssomonas and Pigoraptor are characterized by complex life cycles with a variety of cell types including flagellates, amoeboflagellates, amoeboid non-flagellar cells, and spherical cysts. The life cycles also include the formation of multicellular aggregations and syncytium-like structures, and an unusual diet for single-celled opisthokonts (partial cell fusion and joint sucking of a large eukaryotic prey), all of which provide new insights into the origin of multicellularity in Metazoa. Several existing models explaining the origin of multicellular animals have been put forward, but these data are interestingly consistent with one, the "synzoospore hypothesis." Conclusions: The feeding modes of the ancestral metazoan may have been more complex than previously thought, including not only bacterial prey, but also larger eukaryotic cells and organic structures. The ability to feed on large eukaryotic prey could have been a powerful trigger in the formation and development of both aggregative (e.g., joint feeding, which also implies signaling) and clonal (e.g., hypertrophic growth followed by palintomy) multicellular stages that played important roles in the emergence of multicellular animals.

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“…Another important source of information for phylogenies is the organization of the kinetids (flagellar apparatus). It has been suggested that the ultrastructure of the kinetids is useful for the phylogeny of Porifera (Pozdnyakov & Karpov, ; Pozdnyakov, Sokolova, Ereskovsky, & Karpov, , ). Conversely, we now believe that the general organization and architecture of the aquiferous system observed in previous investigations and in this work (summarized in Table ) do not corroborate the idea that these characteristics are useful to understand/construct the phylogeny of Haplosclerida.…”

Section: Discussionmentioning

confidence: 99%

Anatomy and ultrastructure of the tropical sponge Cladocroce caelum (Haplosclerida, Demospongiae)

Hora

Cavalcanti

Lanna

2018

Journal of Morphology

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The main characteristic of sponges (Porifera) is the presence of the aquiferous system-a system formed by canals and choanocyte chambers, in which the sponges carry out most of their physiological functions. Despite of the importance for the biology of the group, the knowledge about this structure is still incipient, even when morphological investigations are taken in account.Here, we investigated the anatomy and ultrastructure of the tropical demosponge Cladocroce caelum (Haplosclerida, Demospongiae) using light and electron microscopy. In the studied region, specimens of this species were repent or repent-branched, possessing one to several oscula. A uniform and reduced atrium was found just below each osculum. There was a thin ectosome and the choanosome presented meager mesohyl, but a high number of choanocyte chambers. The choanocyte chambers were rounded, and, as in other haplosclerids, they are found separated from the mesohyl by endopinacocytes, "hanging" in the inhalant canals. Even though the utility of the general organization of the aquiferous system has been advocated as a possible tool to understand the phylogeny of the group, we found that these characters might not be as useful as expected. The size of the particles ingested by the sponge and the amount of bacteria to sustain their bodies are discussed. In addition, we found that the density of choanocyte chambers was reduced when the specimens were carrying out the spermatogenesis, indicating that the reproduction may impair the filtering activity of the sponge. Our findings consist in a first step to better comprehend the physiology, development, and adaptation to the environmental conditions where the species is found.

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Kinetid structure in sponge choanocytes of Spongillida in the light of evolutionary relationships within Demospongiae

Cited by 10 publications

References 37 publications

Morphological variability of choanocyte kinetids supports a novel systematic division within Oscarellidae (Porifera, Homoscleromorpha)

Morphological variability of choanocyte kinetids supports a novel systematic division within Oscarellidae (Porifera, Homoscleromorpha)

Insights into the origin of metazoan multicellularity from predatory unicellular relatives of animals

Anatomy and ultrastructure of the tropical sponge Cladocroce caelum (Haplosclerida, Demospongiae)

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