The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform

Shao-en Peng - One of the best experts on this subject based on the ideXlab platform.

  • A detailed observation of the ejection and retraction of defense tissue acontia in sea Anemone (Exaiptasia pallida).
    PeerJ, 2017
    Co-Authors: Julie Lam, Ya-wen Cheng, Wan-nan U. Chen, Chii-shiarng Chen, Shao-en Peng
    Abstract:

    Acontia, located in the gastrovascular cavity of Anemone, are thread-like tissue containing numerous stinging cells which serve as a unique defense tissue against predators of the immobile acontiarian sea Anemone. Although its morphology and biological functions, such as defense and digestion, have been studied, the defense behavior and the specific events of acontia ejection and retraction are unclear. The aim of this study is to observe and record the detailed process of acontia control in Anemones. Observations reveal that the Anemone, Exaiptasia pallida, possibly controls a network of body muscles and manipulates water pressure in the gastrovascular cavity to eject and retract acontia. Instead of resynthesizing acontia after each ejection, the retraction and reuse of acontia enables the Anemone to respond quickly at any given time, thus increasing its overall survivability. Since the Exaiptasia Anemone is an emerging model for coral biology, this study provides a foundation to further investigate the biophysics, neuroscience, and defense biology of this marine model organism.

  • transmission of a heterologous clade c symbiodinium in a model Anemone infection system via asexual reproduction
    PeerJ, 2016
    Co-Authors: Wan-nan U. Chen, Yaju Hsiao, Anderson B Mayfield, Ryan Young, Linglan Hsu, Shao-en Peng
    Abstract:

    Anemones of genus Exaiptasia are used as model organisms for the study of cnidarian-dinoflagellate (genus Symbiodinium) endosymbiosis. However, while most reef-building corals harbor Symbiodinium of clade C, Exaiptasia spp. Anemones mainly harbor clade B Symbiodinium (ITS2 type B1) populations. In this study, we reveal for the first time that bleached Exaiptasia pallida Anemones can establish a symbiotic relationship with a clade C Symbiodinium (ITS2 type C1). We further found that Anemones can transmit the exogenously supplied clade C Symbiodinium cells to their offspring by asexual reproduction (pedal laceration). In order to corroborate the establishment of stable symbiosis, we used microscopic techniques and genetic analyses to examine several generations of Anemones, and the results of these endeavors confirmed the sustainability of the system. These findings provide a framework for understanding the differences in infection dynamics between homologous and heterologous dinoflagellate types using a model Anemone infection system.

Glen M. Watson - One of the best experts on this subject based on the ideXlab platform.

  • The effects of symbiotic state and nutrient availability on the cnidom in the model sea Anemone, Exaiptasia diaphana
    Marine Biology, 2019
    Co-Authors: Katrina A. Gundlach, Glen M. Watson
    Abstract:

    The symbiotic relationship between corals and zooxanthellae allows coral reefs to thrive. The symbiont translocates nutrients which it derives from photosynthesis to the coral, which then uses the nutrients for its growth, reproduction, metabolism, and the maintenance of structural integrity. The majority of the coral’s nutritional input is lost when the coral loses its symbionts in a bleaching event. However, the importance of the symbiotic state to the cnidom of corals remains unknown. The facultative symbiotic Anemone Exaiptasia diaphana, common name Aiptasia, is widely used as a model organism to understand the symbiotic relationship between coral and their symbionts. We experimentally rendered Aiptasia aposymbiotic using a menthol treatment. We exposed symbiotic Anemones and aposymbiotic Anemones to differing feeding regimes to investigate the impact of nutritional input on the cnidom. Symbiotic state and feeding regime significantly affected the: ratio of cnida types in tentacles; the mean volume of cnidae; and the mean density of cnidae in Aiptasia. When Aiptasia becomes aposymbiotic, its tentacles possess more spirocysts and fewer penetrant-type nematocysts. Furthermore, cnidae in aposymbiotic Anemones tended to be smaller than in symbiotic Anemones. In addition, the ratio of cnida types and the mean volume of cnidae were significantly affected by nutrient availability in aposymbiotic Anemones. When nutrients were exogenously supplied, the cnidom of aposymbiotic Anemones became comparable to that of symbiotic Anemones. Moreover, the mean size of cnidae significantly increased. Thus, the cnidom is a dynamic entity that is significantly influenced by the symbiotic state of the Anemone and/or the availability of nutrients.

Peter Holland - One of the best experts on this subject based on the ideXlab platform.

Karen Burke Da Silva - One of the best experts on this subject based on the ideXlab platform.

  • Sea Anemones and Anemonefish: A Match Made in Heaven
    The Cnidaria Past Present and Future, 2016
    Co-Authors: Karen Burke Da Silva, Anita M. Nedosyko
    Abstract:

    Sea Anemones are amongst the most venomous organisms on earth and yet there are species of fish and crustacea that are known to tolerate Anemone venoms and live in association with them in a mutually beneficial relationship. One of natures most compelling displays of symbiotic behavior is found in the relationship between Anemonefish and their sea Anemone host. This relationship was first described more than a century ago and despite it being widely studied since, our understanding of the evolution of the relationship and the mechanisms and behaviors involved remains shrouded in mystery. Anemonefish (Family: Pomacentridae) comprise of a distinct group of 28 species that are able to live within sea Anemones. Despite the large diversity of Anemones in the tropics, only ten species are suitable as hosts for Anemonefish. Within these species, only certain pairs of Anemone and Anemonefish are compatible and found in the wild together. This relationship is obligatory for the fish and in some cases for the Anemone, meaning that the symbionts are entirely or heavily dependent on each other for survival. Symbioses between the two groups provide the following benefits: mutual protection from predators, an exchange of nutrients, improved reproductive and lifetime fitness. While past studies have explored the different patterns of host species that fish use and multiple authors have examined the mechanisms involved in protecting fish from Anemone venom, how fish acquire immunity from the Anemone’s stinging tentacles and why only certain Anemone species are found associated with some Anemonefish more often than others still remains uncertain.

  • Searching for a toxic key to unlock the mystery of Anemonefish and Anemone symbiosis.
    PloS one, 2014
    Co-Authors: Anita M. Nedosyko, Jeanne E. Young, John W. Edwards, Karen Burke Da Silva
    Abstract:

    Twenty-six species of Anemonefish of the genera Amphiprion and monospecific Premnas, use only 10 species of Anemones as hosts in the wild (Families: Actiniidae, Stichodactylidae and Thalassianthidae). Of these 10 Anemone species some are used by multiple species of Anemonefish while others have only a single Anemonefish symbiont. Past studies have explored the different patterns of usage between Anemonefish species and Anemone species; however the evolution of this relationship remains unknown and has been little studied over the past decade. Here we reopen the case, comparing the toxicity of crude venoms obtained from Anemones that host Anemonefish as a way to investigate why some Anemone species are used as a host more than others. Specifically, for each Anemone species we investigated acute toxicity using Artemia francisca (LC50), haemolytic toxicity using ovine erythrocytes (EC50) and neurotoxicity using shore crabs (Ozius truncatus). We found that haemolytic and neurotoxic activity varied among host Anemone species. Generally Anemone species that displayed greater haemolytic activity also displayed high neurotoxic activity and tend to be more toxic on average as indicated by acute lethality analysis. An overall venom toxicity ranking for each Anemone species was compared with the number of Anemonefish species that are known to associate with each Anemone species in the wild. Interestingly, Anemones with intermediate toxicity had the highest number of Anemonefish associates, whereas Anemones with either very low or very high toxicity had the fewest Anemonefish associates. These data demonstrate that variation in toxicity among host Anemone species may be important in the establishment and maintenance of Anemonefish Anemone symbiosis.

Ashley J. Frisch - One of the best experts on this subject based on the ideXlab platform.

  • Anemonefish depletion reduces survival, growth, reproduction and fishery productivity of mutualistic Anemone–Anemonefish colonies
    Coral Reefs, 2016
    Co-Authors: Ashley J. Frisch, Justin R. Rizzari, Katherine P. Munkres, Jean-paul A. Hobbs
    Abstract:

    Intimate knowledge of both partners in a mutualism is necessary to understand the ecology and evolution of each partner, and to manage human impacts that asymmetrically affect one of the partners. Although Anemonefishes and their host Anemones are iconic mutualists and widely sought by ornamental fisheries, the degree to which Anemones depend on Anemonefishes, and thus the colony-level effects of collecting Anemonefishes, is not well understood. We tracked the size and abundance of Anemone Entacmaea quadricolor and Anemonefish Amphiprion melanopus colonies for 3 yr after none, some, or all of the resident Anemonefish were experimentally removed. Total and partial removal of Anemonefish had rapid and sustained negative effects on growth, reproduction and survival of Anemones, as well as cascading effects on recruitment and productivity of Anemonefish in the remaining colony. As predicted, total removal of Anemonefish caused acute declines in size and abundance of Anemones, although most Anemone colonies (76 %) slowly resumed growth and reproduction after the arrival of Anemonefish recruits, which subsequently grew and defended the hosts. Partial removal of Anemonefish had similar but typically less severe effects on Anemones. Remarkably, the colony-level effects on Anemones and Anemonefish were proportional to the size and number of Anemonefish that were experimentally removed. In particular, Anemone survival and Anemonefish productivity were highest when one or more adult Anemonefish remained in the colony, suggesting that adult fish not only enhanced the protection of Anemones, but also increased the recruitment and/or survival of conspecifics. We conclude that the relationship between E. quadricolor and A. melanopus is not only obligate, but also demographically rigid and easily perturbed by Anemonefish fisheries. Clearly, these two species must be managed together as a unit and with utmost precaution. To this end, we propose several tangible management actions that will help to minimize fishing effects.

  • Experimental bleaching of a tropical sea Anemone in situ
    Marine Ecology, 2015
    Co-Authors: Maureen H. Finn, Geoffrey P. Jones, Justin R. Rizzari, Oona M. Lönnstedt, Ashley J. Frisch
    Abstract:

    Bleaching (whitening) of cnidarians such as corals and sea Anemones has caused widespread degradation of coral reefs around the world and is therefore an urgent issue for coral reef science and conservation. Although cnidarians often bleach in aquaria, methods for experimental induction of bleaching in wild cnidarians are lacking, which impedes scientists’ ability to understand the ultimate effects of bleaching on the broader ecosystem. In this study, we investigated the utility of an in situ method for experimental induction of bleaching in the tropical sea Anemone Heteractis crispa. Healthy, wild Anemones were covered with opaque black plastic sheets, mesh cages or left undisturbed (controls) and tentacle colour and body size were monitored with a colour reference card and flexible tape, respectively, every 1–3 days for 15 days. Caged and control Anemones remained unchanged for the duration of the experiment, but covered Anemones commenced whitening after 4–6 days and were completely white after 7–14 days (mean time to bleaching ± SE = 10.1 ± 0.7 days). Experimental bleaching occurred without reduction in Anemone body size and was visibly similar to natural bleaching seen previously in H. crispa. We hypothesize that light-deprivation, reduced water flow, physical contact or some combination of these factors caused the bleaching. This study provides the basis for a simple and rapid method of inducing bleaching in situ, which releases scientists’ dependence on sporadic natural bleaching events or artificial aquarium experiments, and provides a means to investigate the effects of bleaching on other ecosystem components such as fishes.