@article{Edgar_2022,

title = {Ctenophores are direct developers that reproduce continuously beginning very early after hatching},

author = {Allison Edgar and Jos\'{e} Miguel Ponciano and Mark Q. Martindale},

url = {https://doi.org/10.1073/pnas.2122052119},

doi = {10.1073/pnas.2122052119},

year  = {2022},

date = {2022-04-01},

urldate = {2022-04-01},

journal = {Proceedings of the National Academy of Sciences},

volume = {119},

number = {18},

publisher = {Proceedings of the National Academy of Sciences},

abstract = {A substantial body of literature reports that ctenophores exhibit an apparently unique life history characterized by biphasic sexual reproduction, the first phase of which is called larval reproduction or dissogeny. Whether this strategy is plastically deployed or a typical part of these species’ life history was unknown. In contrast to previous reports, we show that the ctenophore Mnemiopsis leidyi does not have separate phases of early and adult reproduction, regardless of the morphological transition to what has been considered the adult form. Rather, these ctenophores begin to reproduce at a small body size and spawn continuously from this point onward under adequate environmental conditions. They do not display a gap in productivity for metamorphosis or other physiological transition at a certain body size. Furthermore, nutritional and environmental constraints on fecundity are similar in both small and large animals. Our results provide critical parameters for understanding resource partitioning between growth and reproduction in this taxon, with implications for management of this species in its invaded range. Finally, we report an observation of similarly small-size spawning in a beroid ctenophore, which is morphologically, ecologically, and phylogenetically distinct from other ctenophores reported to spawn at small sizes. We conclude that spawning at small body size should be considered as the default, on-time developmental trajectory rather than as precocious, stress-induced, or otherwise unusual for ctenophores. The ancestral ctenophore was likely a direct developer, consistent with the hypothesis that multiphasic life cycles were introduced after the divergence of the ctenophore lineage.},

keywords = {Ctenophora, dissogeny, Evolution, larval reproduction, life history, Mnemiopsis leidyi},

pubstate = {published},

tppubtype = {article}

}

@article{Mitchell_2021,

title = {Improved histological fixation of gelatinous marine invertebrates},

author = {Dorothy G. Mitchell and Allison Edgar and Mark Q. Martindale},

url = {https://doi.org/10.1186/s12983-021-00414-z},

doi = {10.1186/s12983-021-00414-z},

year  = {2021},

date = {2021-06-01},

urldate = {2021-06-01},

journal = {Frontiers in Zoology},

volume = {18},

number = {29},

publisher = {Springer Science and Business Media LLC},

abstract = {Background

Gelatinous zooplankton can be difficult to preserve morphologically due to unique physical properties of their cellular and acellular components. The relatively large volume of mesoglea leads to distortion of the delicate morphology and poor sample integrity in specimens prepared with standard aldehyde or alcohol fixation techniques. Similar challenges have made it difficult to extend standard laboratory methods such as in situ hybridization to larger juvenile ctenophores, hampering studies of late development.



Results

We have found that a household water repellant glass treatment product commonly used in laboratories, Rain-X®, alone or in combination with standard aldehyde fixatives, greatly improves morphological preservation of such delicate samples. We present detailed methods for preservation of ctenophores of diverse sizes compatible with long-term storage or detection and localization of target molecules such as with immunohistochemistry and in situ hybridization and show that this fixation might be broadly useful for preservation of other delicate marine specimens.



Conclusion

This new method will enable superior preservation of morphology in gelatinous specimens for a variety of downstream goal. Extending this method may improve the morphological fidelity and durability of museum and laboratory specimens for other delicate sample types.},

keywords = {Ctenophora, fixation, immunohistochemistry, in situ hybridization, Mnemiopsis leidyi, Preservation of zooplankton},

pubstate = {published},

tppubtype = {article}

}

@article{Edgar_2021,

title = {Whole-Body Regeneration in the Lobate Ctenophore Mnemiopsis leidyi},

author = {Allison Edgar and Dorothy G. Mitchell and Mark Q. Martindale},

url = {https://doi.org/10.3390%2Fgenes12060867},

doi = {10.3390/genes12060867},

year  = {2021},

date = {2021-06-01},

urldate = {2021-06-01},

journal = {Genes},

volume = {12},

issue = {6},

pages = {867},

publisher = {MDPI AG},

abstract = {Ctenophores (a.k.a. comb jellies) are one of the earliest branching extant metazoan phyla. Adult regenerative ability varies greatly within the group, with platyctenes undergoing both sexual and asexual reproduction by fission while others in the genus Beroe having completely lost the ability to replace missing body parts. We focus on the unique regenerative aspects of the lobate ctenophore, Mnemiopsis leidyi, which has become a popular model for its rapid wound healing and tissue replacement, optical clarity, and sequenced genome. M. leidyi’s highly mosaic, stereotyped development has been leveraged to reveal the polar coordinate system that directs whole-body regeneration as well as lineage restriction of replacement cells in various regenerating organs. Several cell signaling pathways known to function in regeneration in other animals are absent from the ctenophore’s genome. Further research will either reveal ancient principles of the regenerative process common to all animals or reveal novel solutions to the stability of cell fates and whole-body regeneration.},

keywords = {Ctenophora, Mnemiopsis leidyi, regeneration},

pubstate = {published},

tppubtype = {article}

}