Algae from Aiptasia egesta are robust representations of Symbiodiniaceae in the free-living state

Maruyama, Shumpei; Unsworth, Julia R.; Sawiccy, Valeri; Weis, Virginia M.

doi:10.7717/peerj.13796

Cited by 4 publications

(3 citation statements)

References 48 publications

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“…Our research projects used the presented curriculum and have focused on algal physiology, algal infection of non-symbiotic anemones, and host development during heat stress and various nutritional states (Supporting File S2). Our CURE data has been used in journal and thesis publications (36,37). For more CURE project ideas that involve the sea anemone model system, Poole et al (35) includes lesson plans and protocols spanning biological concepts from molecular to ecological scales.…”

Section: Sea Anemone Cures At Osumentioning

confidence: 99%

Plug and play: A versatile CURE Curriculum for Scientific Process Skills in Upper Division Life Science Labs

Sawiccy¹,

Cai²,

Maruyama³

et al. 2023

Preprint

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Despite the favorable student outcomes and call to increase opportunities for undergraduate research experiences, many students do not have the opportunity to engage in traditional research experiences. Undergraduate institutions are increasing efforts to integrate course-based undergraduate research experiences (CUREs) into undergraduate curricula, however, allocating time for instructors to develop materials is a significant barrier to implementing CUREs in life science laboratories. To streamline the process of developing and implementing CUREs, we present a versatile multi-week curriculum that reinforces scientific process skills and complements a variety of life science CURE research projects conducted in upper-division laboratory courses. By broadening the participation of students in scientific research and facilitating students in essential elements of scientific inquiry, this CURE curriculum can maximize both academic research milestones and student educational gains.

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Section: Sea Anemone Cures At Osumentioning

confidence: 99%

Plug and play: A versatile CURE Curriculum for Scientific Process Skills in Upper Division Life Science Labs

Sawiccy¹,

Cai²,

Maruyama³

et al. 2023

Preprint

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“…Some researchers have used a manual (Bhagooli and Hidaka, 2004;Hawkins et al, 2013) or automated (Dungan et al, 2020;Hartman et al, 2020;Dungan et al, 2022) hemocytometer and/or a flow cytometer (Krediet et al, 2015) to measure in vitro algal density after homogenizing the anemone with its resident symbionts (collectively termed the holobiont). Other researchers have used fluorescent imaging methods (Parkinson et al, 2018;Tortorelli et al, 2020;Presnell et al, 2022) to measure algal density in situ, particularly in early stages of colonization or re-colonization after symbiont loss when algal densities are relatively low (Jinkerson et al, 2022;Maruyama et al, 2022;Tivey et al, 2022). These methods differ not only in cost, efficiency, and convenience, but also in accuracy and precision (Krediet et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Methodological precision of in situ and in vitro algal density measurements in the model cnidarian, Exaiptasia diaphana

Bolzan

Roark

2023

Front. Mar. Sci.

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In cnidarian symbiosis research, studying algal uptake, maintenance, and expulsion typically requires quantification of algal density in host tissue. Multiple methods are used to measure algal density including in vitro cell counts of holobiont homogenate and in situ cell counts of tentacle clippings. The relative precision of both types of measurement has not previously been reported for the model cnidarian Exaiptasia diaphana in the fully symbiotic state. The objective of this study was to evaluate the precision of in vitro and in situ algal density measurement protocols using light, fluorescent, and confocal microscopy and an automated cell counter. In situ algal density was quantified as algal area fraction (%) using confocal images of tentacle clippings mounted on two types of slides. In vitro algal density of holobiont homogenate was quantified as algal cells/µl of holobiont homogenate using an automated cell counter and a hemocytometer viewed using light and fluorescent microscopy. Triplicate measurements of each method for ten anemones were collected and the coefficient of variation was calculated and compared across the ten anemones within each method. The algal density measurements were equally precise when they were obtained by quantifying in vitro cell counts using a hemocytometer and when they were obtained by quantifying in situ cell counts. While both light and fluorescent microscopy yielded similar measurement precision of in vitro cell counts, use of a fluorescent microscope was more efficient and convenient than use of a light microscope, and both methods required terminal sampling. Conversely, in situ methods required more sophisticated equipment (namely a confocal microscope) but involved non-terminal sampling. An automated cell counter was ineffective for in vitro quantification of algal density, although the potential utility of this technology warrants future attempts using a more robust algal cell purification process that could include filtering homogenate prior to analysis. This study demonstrated that in vitro and in situ methods yield estimates of algal density with comparable precision, which is information that researchers can use for future studies when making decisions about methodology.

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“…Functional and structurally intact algae are continuously expelled from the host, generally preserving the ability to colonise new hosts (Ralph et al, 2005;Jacobovitz et al, 2021;Maruyama et al, 2022).…”

Section: Symbiosis Establishment and Maintenancementioning

confidence: 99%

Proteomic insights into osmoregulation and salinity-induced thermotolerance in the cnidarian-dinoflagellate symbiosis

Giovagnoli

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The cnidarian-dinoflagellate symbiosis underpins coral reef success; however, this association is under threat due to the impact of global warming and increasing sea temperatures. Changes in weather patterns have also been projected to occur as the climate warms, leading to more frequent and intense extreme weather events, such as heavy rainfall and droughts, which often trigger sudden and/or prolonged salinity fluctuations. However, our understanding of osmoregulation in the cnidarian-dinoflagellate symbiosis is very limited, especially the homoeostatic mechanisms and physiological effects concerning the dinoflagellate. In addition, some of the most thermotolerant corals in the world dwell in high salinity seas, so it has been proposed that high salinity might confer tolerance against thermal stress. Therefore, the aim of this thesis was to characterise the effects of salinity in Exaiptasia diaphana (Aiptasia) – a model system for the cnidarian-dinoflagellate symbiosis – and cultured symbiotic dinoflagellates (family: Symbiodiniaceae), and to elucidate the relationship between hyper-salinity and thermotolerance. In Chapter 2, Aiptasia in association with its native symbiont, Breviolum minutum, was acclimated to control (35‰) or high salinity (42‰) before being subjected to a thermal stress (26 vs. 33.5 °C). All heat-treated Aiptasia experienced reduced symbiont densities, but those at the control salinity bleached significantly more and exhibited lower photosynthetic performance. At the cellular level, hyper-salinity induced the downregulation of the immune response and protein homeostasis in the host at both temperatures (26 and 33.5 °C), while the differential regulation of betaine metabolism proteins suggested that accumulation of betaines is an important osmoregulatory mechanism in Aiptasia. At elevated temperature, an increased abundance of stress-related proteins and enzymes involved in lipid and protein degradation, along with a downregulation of metabolite transporters, was detected in the host irrespective of salinity, consistent with the host receiving less nutritional benefit from the symbiont. The symbiont proteomic response notably differed from that of the host, with exposure to hyper-salinity causing extensive differences under thermal stress, but nearly none at the control temperature. A greater impairment of photosynthetic processes and a more evident shift in metabolic pathways of energy production were observed in thermally-compromised dinoflagellates at the control salinity compared to those exposed to high salinity. These results support the idea that when exposed to thermal stress, hyper-salinity confers thermotolerance in the cnidarian-dinoflagellate symbiosis, resulting in a more stable and beneficial symbiosis. The cytoprotectant/antioxidant properties of the accumulated osmolytes and the modulation of the host immune response are some of the putative mechanisms involved in this higher resistance to elevated temperature at the high salinity. In Chapter 3, a study exposing different Symbiodiniaceae (Symbiodinium microadriaticum, Breviolum minutum and Durusdinium trenchii) to increasing or decreasing salinities showed that the three species were exceptionally tolerant to gradual changes, persisting at values below 1‰ and above 60–70‰, although cell numbers declined under these conditions. This considerably exceeds the salinity range at which coral reefs are exposed on a regular basis (25–42‰). In a subsequent experiment, the physiological and proteomic response of these species was evaluated when exposed to the final salinities of 25‰ (low), 35‰ (control) and 42‰ (high). As expected, physiological responses did not show a negative impact under these conditions, though the proteome exhibited significant differences depending on the species and the treatment. Photosynthetic proteins were upregulated in S. minutum and D. trenchii at low and high salinity, while B. minutum exhibited a contradictory pattern at high salinity, with increased abundance of proteins that fix carbon and a decreased abundance of proteins that supply carbon for photosynthesis. Lipid metabolism was affected by salinity, and this also depended on species and salinity treatment. Increased abundance of antioxidants and chaperones was observed in all species, with S. microadriaticum showing a greater abundance at low salinity, D. trenchii at high salinity, and B. minutum at both. High salinity induced an increase in methionine cycle enzymes in all species, suggesting that this is a conserved response to hyper-osmotic conditions. The differential regulation of protein kinases and phosphatases among salinities was noted, emphasising the role of post-translational modifications for dealing with environmental change. Finally, a few ion pumps and channels were differentially abundant, especially those that decrease the ion permeability of the membrane at low salinity, preventing the leakage of essential ions.This thesis has provided detailed cellular and molecular insight into the mechanisms underlying the effects of stressors associated with climate change in the model system Aiptasia and in different Symbiodiniaceae species, which has the potential to serve as a foundation for future research on coral bleaching, and for the development of tools to mitigate the impacts of global warming.

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Algae from Aiptasia egesta are robust representations of Symbiodiniaceae in the free-living state

Cited by 4 publications

References 48 publications

Plug and play: A versatile CURE Curriculum for Scientific Process Skills in Upper Division Life Science Labs

Plug and play: A versatile CURE Curriculum for Scientific Process Skills in Upper Division Life Science Labs

Methodological precision of in situ and in vitro algal density measurements in the model cnidarian, Exaiptasia diaphana

Proteomic insights into osmoregulation and salinity-induced thermotolerance in the cnidarian-dinoflagellate symbiosis

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