| 1. |
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| 2. |
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| 3. |
- Goddek, Simon, et al.
(author)
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Decoupled aquaponic systems
- 2019
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In: Aquaponics Food Production Systems. - London : Springer. - 9783030159436
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Book chapter (peer-reviewed)
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| 4. |
- Goddek, Simon, et al.
(author)
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How greenhouse horticulture in arid regions can contribute to climate-resilient and sustainable food security
- 2023
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In: GLOBAL FOOD SECURITY-AGRICULTURE POLICY ECONOMICS AND ENVIRONMENT. - 2211-9124. ; 38
-
Journal article (peer-reviewed)abstract
- A potential change in climate and temperature could strongly affect weather-related crop losses. Using wastelands to grow crops in controlled greenhouse environments could improve global food security and preserve ecosystems. However, the impact of climate change on additional energy and water requirements of greenhousehorticulture food production is still unknown. Using a greenhouse simulator for four locations (The Netherlands, Spain, Saudi Arabia and Namibia), we show that a rise in outdoor temperatures can be counterbalanced with a more intensive water-based cooling. Between 6.9% and 17.9%, more water is required in the worst-case scenario in the year 2100, while the yield quantity decreases by 3%-6% due to slightly deteriorating growth conditions within the greenhouse. Since cooling systems consume up to 90% of the total water use in desert greenhouses, saltwater cooling could play an essential role in increasing the efficiency and sustainability of greenhouse horticulture systems in arid regions. In this study, we investigate the economic and technical feasibility of such greenhouse systems on a larger scale and show the massive potential of these systems. The developed scenarios demonstrate considerable climate resilience, enabling the cultivation of fresh vegetables in arid and infertile regions both presently and in the future.
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| 5. |
- Goddek, S., et al.
(author)
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Nutrient mineralization and organic matter reduction performance of RAS-based sludge in sequential UASB-EGSB reactors
- 2018
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In: Aquacultural Engineering. - : Elsevier BV. - 0144-8609 .- 1873-5614. ; 83, s. 10-19
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Journal article (peer-reviewed)abstract
- There is a recognized need for mineralizing aquaculture-derived sludge in aquaponics systems in order to reduce waste production. Many recent studies of aquacultural waste treatment have focused only the production of biogas as opposed to the potential for mineralization of nutrient-rich sludge. Upflow anaerobic sludge blanket (UASB) reactors provide one possible solution for breaking down sludge into bioavailable nutrients that can subsequently be delivered to plants. As such, this study examines the mineralization performance of sequential UASB reactors that are designed with an expanded granular sludge bed (EGSB) and compared to standard aerobic and anaerobic batch reactors. Results of our experiments demonstrate that only chemical oxygen demand reduction is significantly different. An unexpected drop in pH of one of the three reactor systems revealed that a pH below 6 was able to significantly increase the mineralization and mobilization of nutrients. Approximately 25% of phosphorus, potassium, and calcium could also be recovered from the sludge under lower pH conditions, as compared to the mineralization performance of standard UASB reactors running at a higher pH. However, the opposite effect was observed with respect to organic sludge reduction, where diminished performance was observed in the low-pH reactor. The current study implies that anaerobic reactors operating at low pH can potentially contribute towards improved nutrient recovery in multi-loop aquaponics systems and reduction of additive agents for pH control of the hydroponic subsystem. © 2018 Elsevier B.V.
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| 6. |
- Horn, Erin Kelly, et al.
(author)
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Translating Environmental Potential to Economic Reality: Assessment of Commercial Aquaponics through Sustainability Transitions Theory
- 2024
-
In: Circular Economy and Sustainability. - 2730-597X .- 2730-5988. ; 4:1, s. 523-554
-
Journal article (peer-reviewed)abstract
- Despite popular interest and recent industry growth, commercial-scale aquaponics still faces economic and regulatory barriers primarily resulting from political and economic systems which insufficiently address pressing environmental challenges. The sustainability potential of aquaponic food production can help address and overcome such challenges while contributing to the broader development of circular economy and sustainable development of food systems. In response to the current counterproductive gap between potential applications and industry development, the interdisciplinary team of authors identifies pathways to translate the environmental potential of commercial aquaponics into economic success through a sustainability transition theory lens. To evaluate the industry’s current state-of-the-art, drivers, barriers, and future potential, interview data from 25 North American producers collected in 2021, literature, and policy are analyzed through a Technological Innovation System (TIS) assessment within a Multi-Level Perspective (MLP) approach. This supports the consideration of pathways for industry development of aquaponics as an aspect of circular economy within a dynamic sustainable development context. These pathways for action include (1.) advancing clear standards and policies for aquaponics as part of a circular economy, increasing funding and incentives, and reducing support and subsidies for competing unsustainable food production; (2.) developing and promoting cost-effective technologies; and (3.) bolstering consumer preferences for sustainable and healthy food sources.
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| 7. |
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| 8. |
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| 9. |
- Joyce, Alyssa, et al.
(author)
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Experimental effects of temperature and photoperiod on synchrony of gametogenesis and sex ratio in the European oyster Ostrea edulis (Linnaeus)
- 2013
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In: Journal of Shellfish Research. - : National Shellfisheries Association. - 0730-8000 .- 1943-6319. ; 32:2, s. 447-458
-
Journal article (peer-reviewed)abstract
- Insufficient knowledge about physiological processes underpinning reproduction in the European flat oyster, Ostrea edulis (Linnaeus), presents a number of unique challenges when designing a large-scale selective breeding program for hatchery production. The European flat oyster is a larviparous, protandric hermaphrodite wherein asynchronous spawns and variable sex ratios can lead to loss of genetic diversity and inbreeding depression within hatchery populations as a result of disproportionate gametic contributions in mass matings. A better understanding of O. edulis physiology in relation to environmental factors has the potential to improve hatchery processes for synchronization of gametogenesis, thus increasing fertilization potential and maximizing breeding population size of broodstock. This study sought to determine whether specific conditioning procedures-notably, manipulation of temperature and photoperiod-could be used to improve synchrony of gametogenesis and predictability of sex ratios in O. edulis. Two trials of accelerated yearly variations of temperature and photoperiod were conducted to uncouple the specific role of these factors in the timing of gametogenesis and sex of gametes over several spawning cycles. Histological analysis and quantitative analysis of gonad using a gonad filling index allowed for determination of sex ratios and staging of gametogenesis. Temperature was a controlling factor, although experimental results suggested that the effects of photoperiod, uncoupled from temperature, had no effect on the timing or rate of gametogenesis, or on sex ratios during a breeding season. A better understanding of factors affecting sex ratio and synchrony in timing of gamete release will allow for improved conditioning and broodstock handling protocols in the selective breeding of O. edulis.
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| 10. |
- Joyce, Alyssa, et al.
(author)
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Molluscan bivalve settlement and metamorphosis: Neuroendocrine inducers and morphogenetic responses
- 2018
-
In: Aquaculture. - : Elsevier BV. - 0044-8486. ; 487, s. 64-82
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Journal article (peer-reviewed)abstract
- Surprisingly little is known about the nature and function of neurohormones in molluscs despite the fact that many of the neurotransmitters, including serotonin, catecholamines and estrogenic compounds that regulate reproduction in humans are also found in bivalve molluscs. Although mammalian and fish sex neurotransmitters have been comparatively well-studied, their role in molluscs is an emerging field where recent molecular and genetic research reveals an increasingly nuanced understanding of neuroendocrine pathways and morphogenetic processes. This knowledge is important in eco-toxicology given the prevalence of anthropogenic pollutants such as pharmaceuticals in wastewater, as well as pesticides and insecticides that are known to interfere with neuroendocrine signalling in a wide range invertebrate and vertebrate species. Knowledge of these pathways in molluscs is also important when developing anti-fouling compounds for marine applications. In the last few decades, the use of chemical inducers in bivalve aquaculture has transformed hatchery technology not only by increasing survival rates at metamorphosis, but also by using neurohormones to create ‘cultchless’ or ‘single-seed’ spat in some species (e.g. oysters) to bypass normal pathways that involve attachment to a substrate. Hatchery protocols for inducing settlement and metamorphosis with a range of chemical inducers in commercial shellfish species have been developed primarily from empirical studies based on trial and error, but such an approach is not reliably effective in all species, and trial and error is particularly time-consuming when developing protocols for new species. During the transition from larval to juvenile to adult life stages, neuroendocrine and immune functions mediate complex metabolic processes, and recent research on hematopoiesis, immune-competence, neuroendocrine pathways and gene regulation give insights into these complexities. In this review, we provide a current overview of research regarding the neuroendocrine basis for physiological mechanisms involved in bivalve settlement and metamorphosis, given it is a period when hatcheries often experience the greatest losses. Despite a plethora of empirical studies on specific species, the processes and neurotransmitters involved are surprisingly not well explored. We focus on metamorphosis as a key developmental period by highlighting some of the most promising new research in this area, with a focus on the value of these insights for commercial applications in aquaculture. © 2018 The Authors
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| 11. |
- Joyce, Alyssa, et al.
(author)
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The role of exopolymers in hatcheries: an overlooked factor in hatchery hygiene and feed quality
- 2015
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In: Aquaculture. - : Elsevier BV. - 0044-8486. ; 446, s. 122-131
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Journal article (peer-reviewed)abstract
- Extracellular Polymeric Substances (EPS),(1) or exopolymers, play vital roles in the productivity of commercial hatcheries, yet have received little attention in aquaculture outside of their role in the biofilters of recirculating systems. Hatcheries have long dealt with EPS in microalgal cultures or larval rearing systems when quantities manifest themselves visually as biofilms or mucilaginous aggregates. The same polymers in lesser, visually undetectable quantities have the ability to attract commensal bacteria and sequester micronutrients, which can be essential in hatcheries for hygiene, stability of rearing environments, and the production of microalgae for live feeds. EPS may also serve an important role in nutrition both directly in the particle selection of filter feeders, and indirectly through their contribution to microflora in the larval gut of both fish and invertebrates. EPS have been well-studied in marine ecosystems, but their presence in hatcheries has until recently been largely overlooked, perhaps on account of their invisibility using normal microscopy and their extremely small size, both factors which may explain why they are sometimes also referred to as transparent exopolymeric substances (TEPs). This review examines recent literature for ways in which EPS affect hatchery processes, with suggestions as to how further research and development of biosensor technologies for EPS have the potential to improve production processes. (C) 2015 The Authors. Published by Elsevier B.V.
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| 12. |
- Joyce, Alyssa, et al.
(author)
-
Toward Selective Breeding of a Hermaphroditic Oyster Ostrea chilensis: Roles of Nutrition and Temperature in Improving Fecundity and Synchrony of Gamete Release
- 2015
-
In: Journal of Shellfish Research. - : National Shellfisheries Association. - 0730-8000 .- 1943-6319. ; 34:3, s. 831-840
-
Journal article (peer-reviewed)abstract
- Physiological characteristics of gametogenesis, fertilization, and early larval development in Ostrea chilensis (Philippi, 1845) pose a number of challenges for selective breeding, despite strong commercial potential. In wild populations, this larviparous protandric hermaphrodite exhibits asynchronous gonadal maturation and relatively low fecundity. Reproductive success and genetic diversity in a hatchery population are primarily determined by female fecundity and fertility, as well as synchrony of female gonad development. Better hatchery control of the reproductive cycle can lead to more cost-effective and reliable breeding. This study examined factors such as feed and temperature in an attempt to increase reproductive rates and female sex ratios in brood stock. Oysters held under two different hatchery conditioning regimes-flow-through outdoor nursery ponds and temperature-controlled indoor tanks-spawned earlier and had higher reproductive rates than natural or farmed populations. Oysters were sampled over 6 months with histological analysis used to assess seasonal gamete patterns. Magnetic resonance imaging was also trialed and compared with histology findings. Significant increase in female gonad proportion and improved synchrony of egg maturation was observed through manipulation of feed and temperature. The implications of these findings for implementing a cost-effective selective breeding program in this species are outlined.
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| 13. |
- Linders, Torsten, 1971, et al.
(author)
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Particle sources and transport in stratified Nordic coastal seas in the Anthropocene
- 2018
-
In: Elementa: Science of the Anthropocene. - : University of California Press. - 2325-1026. ; 6:1
-
Research review (peer-reviewed)abstract
- Particles of all origins (biogenic, lithogenic, as well as anthropogenic) are fundamental components of the coastal ocean and are re-distributed by a wide variety of transport processes at both horizontal and vertical scales. Suspended particles can act as vehicles, as well as carbon and nutrient sources, for microorganisms and zooplankton before eventually settling onto the seafloor where they also provide food to benthic organisms. Different particle aggregation processes, driven by turbulence and particle stickiness, composition, abundance and size, impact the transport and sinking behavior of particles from the surface to the seafloor. In deep coastal waters, the deposition, resuspension, and accumulation of particles are driven by particle stickiness, composition and aggregate structure. In contrast, wave-driven and bottom current-driven processes in the nepheloid benthic boundary layer of shallow waters are of greater importance to the settling behavior of particles, while the retention capacity of benthic vegetation (e.g., seagrasses) further influences particle behavior. In this review, we consider the various processes by which particles are transported, as well as their sources and characteristics, in stratified coastal waters with a focus on Nordic seas. The role of particles in diminishing the quality of coastal waters is increasing in the Anthropocene, as particle loading by rivers and surface run-off includes not only natural particles, but also urban and agricultural particles with sorbed pollutants and contaminants of organic, inorganic and microplastic composition. Human activities such as trawling and dredging increase turbidity and further impact the transport of particles by resuspending particles and influencing their vertical and horizontal distribution patterns. An interdisciplinary approach combining physical, chemical and biological processes will allow us to better understand particle transport and its impact on coastal waters and estuaries at an ecosystem level. There is a need for development of novel analytical and characterization techniques, as well as new in situ sensors to improve our capacity to follow particle dynamics from nanometer to millimeter size scales.
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| 14. |
- Lobanov, Victor P., et al.
(author)
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Ecosystem-specific microbiota and microbiome databases in the era of big data
- 2022
-
In: Environmental Microbiome. - : Springer Science and Business Media LLC. - 2524-6372. ; 17:1
-
Journal article (peer-reviewed)abstract
- The rapid development of sequencing methods over the past decades has accelerated both the potential scope and depth of microbiota and microbiome studies. Recent developments in the field have been marked by an expansion away from purely categorical studies towards a greater investigation of community functionality. As in-depth genomic and environmental coverage is often distributed unequally across major taxa and ecosystems, it can be difficult to identify or substantiate relationships within microbial communities. Generic databases containing datasets from diverse ecosystems have opened a new era of data accessibility despite costs in terms of data quality and heterogeneity. This challenge is readily embodied in the integration of meta-omics data alongside habitat-specific standards which help contextualise datasets both in terms of sample processing and background within the ecosystem. A special case of large genomic repositories, ecosystem-specific databases (ES-DB's), have emerged to consolidate and better standardise sample processing and analysis protocols around individual ecosystems under study, allowing independent studies to produce comparable datasets. Here, we provide a comprehensive review of this emerging tool for microbial community analysis in relation to current trends in the field. We focus on the factors leading to the formation of ES-DB's, their comparison to traditional microbial databases, the potential for ES-DB integration with meta-omics platforms, as well as inherent limitations in the applicability of ES-DB's.
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| 15. |
- Lobanov, Victor P., et al.
(author)
-
Improving Plant Health Through Nutrient Remineralization in Aquaponic Systems
- 2021
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In: Frontiers in Plant Science. - : Frontiers Media SA. - 1664-462X. ; 12
-
Journal article (peer-reviewed)abstract
- The exploitation of readily bioavailable fish excreta as a source of plant nutrients lies at the cornerstone of aquaponics farming. Research on nutrient cycling in aquaponic systems has devoted considerable attention to the plant uptake of dissolved nutrients in fish excreta, however, the integration of particulate-bound nutrients into downstream hydroponic farming has remained elusive. The high amount of organic carbon present in fish sludge may lead to biofouling if directly incorporated into hydroponic circulation systems, reducing the utility of incorporating fish solids on a large scale. In this study, we implemented a novel treatment system capable of reducing the carbon and nitrogen load of fish solids to produce a liquid fertilizer for a downstream hydroponics unit. Lettuce (Lactuca sativa) fertilized with exclusively a commercial nutrient solution, the biofilter effluent (coupled aquaponic system), effluent from the solids treatment system, or the latter two combined were grown in nutrient flow technique gutters downstream of a recirculating aquaculture system stocked with rainbow trout (Oncorhynchus mykiss). While crop yields were lower for the aquaponic treatments compared to lettuce grown in a commercial nutrient solution, plant sap analysis demonstrated a contrasting picture with respect to internal nutrient concentrations. Lettuce grown in the commercial hydroponic solution were deficient in several mineral nutrients (Mg, Ca, Na, and Si) nor did they have higher iron concentrations despite the significantly higher EDTA-chelated aqueous iron (460 x greater than other treatments) in the nutrient solution. Nutrient uptake in the rhizosphere was not investigated on a molecular level, although stunted rhizosphere growth in the commercial nutrient solution control suggests a weakened capacity for nutrient uptake in comparison to other treatments. Alongside the remineralization of micronutrients, the solids treatment system addressed the common issue of excess carbon leading to biofouling via a total suspended solids reduction of 87.27% +/- 9.95 during the coupled aquaponics cultivation period. Ultimately, these data lead to two important conclusions. Firstly, optimizing nutrient bioavailability is not synonymous to increasing the presence of a nutrient in the water column. Secondly, estimating ideal nutrient solution concentrations involves both preventing nutrient blocking and improving bioavailability.
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| 16. |
- Lobanov, Victor P., et al.
(author)
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Simultaneous biomethane production and nutrient remineralization from aquaculture solids
- 2023
-
In: Aquacultural Engineering. - : Elsevier BV. - 0144-8609. ; 101
-
Journal article (peer-reviewed)abstract
- The rapid expansion of the aquaculture industry has brought about a heightened focus on the waste produced by high intensity fish farming. In closed-containment, recirculating aquaculture systems (RAS), fish solids are mechanically separated and/or coagulated before being disposed as waste. Subsequent revalorization is typically limited to the direct dispersal of aquaculture solids onto agricultural fields. Here, we developed a novel, continuous flow, low-cost solids waste treatment system for freshwater and saline RAS. Rotating drum filter backwash was collected as the primary feedstock for anaerobic digestion. A laboratory scale set up was used to monitor the conversion of the solids into a methane-rich (60-80% purity) biogas stream. Iron supplementation (ferric iron at 100 mg/L and 1000 mg/L) improved salt tolerance of the methanogenic community, leading to higher methane yields in a supplemented (FeCl3 at 1000 mg/L) saline treatment than the saline control. The application of iron additionally improves pH stability and volatile fatty acid utilization. The methane yield ranged from 0.1 to 0.4 NL CH4/ g VS across the three freshwater treatments and the iron-supplemented saline treatment, however, it was significantly lower for the saltwater control: ranging between 0.08 and 0.25 NL CH4/ g VS. These values correspond to a percentage yield of 57-86% of the total biomethane potential. Overall, implementing anaerobic digestion for RAS waste valorization may generate significant amounts of biomethane to be used in electricity and heating for large-scale aquaculture facilities, while even for smaller facilities it may off-set costs and mitigate environmental impacts of the waste streams.
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| 17. |
- Lobanov, Victor P., et al.
(author)
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Sturgeon and paddlefish: Review of research on broodstock and early life stage management
- 2023
-
In: Aquaculture and Fisheries. - 2096-1758 .- 2468-550X.
-
Research review (peer-reviewed)abstract
- Sturgeon aquaculture has taken a parallel yet unique path relative to other teleost rearing. One of the driving factors has been the fact that virtually all extant species are facing extinction; thus, laws concerning the transport and processing of sturgeon are stringent. As a result, most sturgeon companies vertically integrate the farming process from hatchery to harvest, in contrast to the production of other commercial fish species (e.g., trout, sea bass, salmon), where farmers tend to purchase fry from producers specialized only in the production of that life stage and sell product to unaffiliated fish processors. Sturgeon aquaculture is furthermore unique in the extremely high value of the main product (caviar). The secondary product (meat) also surpasses other finfish aquaculture products' average price per weight. These expensive outputs reveal the greatest challenge in production — an exceptionally long time to market from larvae to harvestable adults. For all their rigor and robustness as juveniles and adults, sturgeon species are highly fragile during larval stages. Due to the unique legal framework around sturgeon cultivation, aquaculturists often specialize in regional species, although some hybrids have achieved global popularity. This lends to a heterogenous swath of literature on best cultivation and management practices, especially at early growth stages. Nonetheless, the role of aquaculture as both a food source and restocking program to thwart further extinction of sturgeon species has hardly been fully tapped. In light of the many challenges, this review examines recent advances in sturgeon farming with an emphasis on broodstock and early life-stage management to summarize studies that can help researchers and farmers assess the industry's current state.
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| 18. |
- Lobanov, Victor, et al.
(author)
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Plants Dictate Root Microbial Composition in Hydroponics and Aquaponics
- 2022
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In: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 13
-
Journal article (peer-reviewed)abstract
- The role of the microbial community in mediating fish and plant co-culture is often considered the black box of aquaponics. Despite widespread recognition regarding the dependency of plants on their rhizosphere, the extent to which upstream aquaculture influences downstream hydroponic root communities has been poorly described in the literature. In this study we performed a taxonomic survey (16S rRNA metabarcoding) of microbial communities originating in the facility water source, hydroponic nutrient solution (HNS) sump, nutrient supplemented biofilter effluent (BF) sump, and recirculating aquaculture system tanks stocked with Nile tilapia (Oreochromis niloticus). Lettuce (Lactuca sativa) was then grown using the HNS and BF effluent under sterilized or mature (prior aquaponics/hydroponics lettuce culture water) conditions, likewise, the influence of probiotic addition or inoculation with soil-grown lettuce rhizosphere was assessed. Compositional similarities across treatments suggest that under soil-less conditions, plants are able to exert a stronger discriminatory influence on their rhizosphere composition than is done by colonization from upstream sources. Furthermore, cluster dendrograms grouped the sterilized and unsterilized treatments more consistently together than hydroponics and aquaponics treatments. These findings contradict conventional beliefs that microbial communities in the water column colonize roots based on their presence alone, ignoring the role that plants play in rhizosphere community selection.
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| 19. |
- Mardones-Toledo, D. A., et al.
(author)
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Brooding in the Chilean oyster Ostrea chilensis: Unexpected complexity in the movements of brooded offspring within the mantle cavity
- 2015
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In: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:4
-
Journal article (peer-reviewed)abstract
- Brooding in invertebrates serves to protect embryos from stressful external conditions by retaining progeny inside the female body, effectively reducing the risk of pelagic stages being exposed to predation or other environmental stressors, but with accompanying changes in pallial fluid characteristics, including reduced oxygen availability. Brooded embryos are usually immobile and often encapsulated, but in some Ostrea species the embryos move freely inside the female pallial cavity in close association with the mother's gills for as long as eight weeks. We used endoscopic techniques to characterize the circulation pattern of embryos brooded by females of the oyster, Ostrea chilensis. Progeny at embryonic and veliger stages typically circulated in established patterns that included the use of dorsal and ventral food grooves (DFG, VFG) to move anteriorly on the gills. Both embryos and veligers accumulated around the mother's palps, and remained there until an active maternal countercurrent moved them to the gill inhalant area. Both food grooves were able to move embryos, veligers, and food-particle aggregates anteriorly, but the DFG was more important in progeny transport; early embryos were moved more rapidly than veligers in the DFG. A microcirculation pattern of embryos was apparent when they were moved by gill lamellae: when they were close to the VFG, most embryos lost gill contact and "fell" down to the DFG. Those that actually reached the DFG moved anteriorly, but others came into contact with the base of the lamellae and again moved towards the VFG. The circulation pattern of the progeny appears well-suited for both cleaning them and directing them posteriorly to an area where there is more oxygen and food than in the palp region. This process for actively circulating progeny involves the feeding structures (gill and palps) and appears to be energetically costly for the female. It also interferes with feeding, which could explain the poor energy balance previously documented for brooding females of this species. © 2015 Mardones-Toledo et al.
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| 20. |
- Mougin, Julia, 1994, et al.
(author)
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Benzalkonium chloride disinfectant residues stimulate biofilm formation and increase survival of Vibrio bacterial pathogens
- 2024
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In: FRONTIERS IN MICROBIOLOGY. - 1664-302X. ; 14
-
Journal article (peer-reviewed)abstract
- Vibrio spp. are opportunistic human and animal pathogens found ubiquitously in marine environments. Globally, there is a predicted rise in the prevalence of Vibrio spp. due to increasing ocean temperatures, which carries significant implications for public health and the seafood industry. Consequently, there is an urgent need for enhanced strategies to control Vibrio spp. and prevent contamination, particularly in aquaculture and seafood processing facilities. Presently, these industries employ various disinfectants, including benzalkonium chloride (BAC), as part of their management strategies. While higher concentrations of BAC may be effective against these pathogens, inadequate rinsing post-disinfection could result in residual concentrations of BAC in the surrounding environment. This study aimed to investigate the adaptation and survival of Vibrio spp. exposed to varying concentrations of BAC residues. Results revealed that Vibrio bacteria, when exposed, exhibited a phenotypic adaptation characterized by an increase in biofilm biomass. Importantly, this effect was found to be strain-specific rather than species-specific. Exposure to BAC residues induced physiological changes in Vibrio biofilms, leading to an increase in the number of injured and alive cells within the biofilm. The exact nature of the "injured" bacteria remains unclear, but it is postulated that BAC might heighten the risk of viable but non-culturable (VBNC) bacteria development. These VBNC bacteria pose a significant threat, especially since they cannot be detected using the standard culture-based methods commonly employed for microbiological risk assessment in aquaculture and seafood industries. The undetected presence of VBNC bacteria could result in recurrent contamination events and subsequent disease outbreaks. This study provides evidence regarding the role of c-di-GMP signaling pathways in Vibrio adaptation mechanisms and suggests that c-di-GMP mediated repression is a potential avenue for further research. The findings underscore that the misuse and overuse of BAC may increase the risk of biofilm development and bacterial survival within the seafood processing chain.
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| 21. |
- Mougin, Julia, 1994, et al.
(author)
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Effects of dietary co-exposure to fungal and herbal functional feed additives on immune parameters and microbial intestinal diversity in rainbow trout (Oncorhynchus mykiss)
- 2023
-
In: Fish & Shellfish Immunology. - 1050-4648. ; 137
-
Journal article (peer-reviewed)abstract
- Misuse and overuse of antibiotics in aquaculture has proven to be an unsustainable practice leading to increased bacterial resistance. An alternative strategy involves the inclusion of immunostimulants in fish diets, especially fungal and herbal compounds already authorized for human consumption, hence without environmental or public health concerns. In this study, we used a holistic and cross-disciplinary pipeline to assess the immunos-timulatory properties of two fungi: Trametes versicolor and Ganoderma lucidum; one herbal supplement, capsaicin in the form of Espelette pepper (Capsicum annuum), and a combination of these fungal and herbal additives on rainbow trout (Oncorhynchus mykiss). We investigated the impact of diet supplementation for 7 weeks on sur-vival, growth performance, cellular, humoral, and molecular immune parameters, as well as the intestinal mi-crobial composition of the fish. Uptake of herbal and fungal compounds influenced the expression of immune related genes, without generating an inflammatory response. Significant differences were detected in the spleen-tlr2 gene expression. Supplementation with herbal additives correlated with structural changes in the fish in-testinal microbiota and enhanced overall intestinal microbial diversity. Results demonstrated that the different treatments had no adverse effect on growth performance and survival, suggesting the safety of the different feed additives at the tested concentrations. While the mechanisms and multifactorial interactions remain unclear, this study provides insights not only in regard to nutrition and safety of these compounds, but also how a combined immune and gut microbiota approach can shed light on efficacy of immunostimulant compounds for potential commercial inclusion as feed supplements.
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| 22. |
- Mougin, Julia, 1994, et al.
(author)
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Fish disease prevention via microbial dysbiosis-associated biomarkers in aquaculture
- 2022
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In: Reviews in Aquaculture. - : Wiley. - 1753-5123 .- 1753-5131. ; 15:2, s. 579-94
-
Research review (peer-reviewed)abstract
- Infectious diseases are a major burden in aquaculture, and represent a significant yield-limiting factor in production that is costly to manage as well as a potential vector for zoonoses. Over the past decades, a range of new diseases have emerged, alongside increased levels of antibiotic resistance, thus heightening the need for improved disease management methods supportive of the One Health concept. Simultaneously, recent advances in Next-Generation Sequencing have increasingly elucidated the role of the microbiome in regulating metabolism, immune function and resilience. Such work has included a plethora of studies on the potential for the management of pathogens through manipulation of the microbiome, as well as related studies of the mechanisms behind host resilience. There is now an increasing robust body of evidence recognizing the importance of a holistic framework in disease aetiology between the host, its environment and colonizing microorganisms, with perturbation increasingly associated with specific dysbiotic states and disease outcomes. Elucidating disease aetiology is a preliminary step towards the development of new prevention methods, with the main goal being early identification of dysbiosis-associated biomarkers prior to any physical signs of the disease. While acknowledging the challenges associated with using key microbial taxa as biomarkers, we review recent advances in the characterization of dysbiosis and associated microbiome signatures in the context of disease development, with an emphasis on early biomarkers for aquaculture disease prevention. Several promising strategies are suggested, including the use of functional genes or metabolic pathways that are conserved between microbial taxa as a potential proxy for homeostasis.
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| 23. |
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| 24. |
- Sauvage, Justine, et al.
(author)
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Bacterial exudates as growth-promoting agents for the cultivation of commercially relevant marine microalgal strains
- 2022
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In: Journal of the World Aquaculture Society. - : Wiley. - 0893-8849 .- 1749-7345. ; 53:6, s. 1101-1119
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Journal article (peer-reviewed)abstract
- In laboratory and industrial cultivation of marine microalgae, it is customary to enrich cultures with macronutrients (N, P), chelated trace metals, and vitamins at similar to 10(4) x concentrations found in nature to obtain high culture densities. Other naturally occurring growth-promoting compounds found in local seawater are not enriched and remain at environmental concentrations. Microalgae may thus be deprived of the mutualistic contributions of co-occurring microorganisms with which they have evolved complex chemical relationships. In the present study, we assess the direct (mixed bacteria-microalgae cultivation) and indirect (exposure to exudates only, without physical contact) effects of 10 bacterial strains on the growth of five marine microalgal strains used as feeds in marine aquaculture hatcheries. Bacterial strains were selected based upon previously reported growth-promoting characteristics in plants or microalgae, or known release of probiotics. Our experiments demonstrate superior stimulation of microalgal growth by bacterial exudates, and without the presence of the bacteria that produced these exudates. However, response to bacterial exudate enrichment was dependent upon the microalgae strain and bacterial pairing. Exudates from Bacillus, Mesorhizobium, arid Phaeobacter strains were most effective, with 22%-69% increases in microalgal specific growth rate. Such findings indicate that bacterial exudates accelerate rate-limiting processes governing nutrient acquisition, assimilation, or anabolism, and possibly algal release of exopolymeric substances. Maximal cell density, however, remained constrained by macronutrient limitation. Scaledup trials in an oyster hatchery confirmed the practical benefit of bacterial exudate culture medium enrichment and demonstrated the suitability of exudate-enriched microalgae to feed hatchery-reared bay scallops. This work presents a promising strategy to improve microalgal culture media formulations using bacterial exudate components as growth promoters, and is the first such study to identify specific pairings with relevance for aquaculture production.
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| 25. |
- Sauvage, Justine, et al.
(author)
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Biodegradable, metal-chelating compounds as alternatives to EDTA for cultivation of marine microalgae
- 2021
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In: Journal of Applied Phycology. - : Springer Science and Business Media LLC. - 0921-8971 .- 1573-5176. ; 33, s. 3519-3537
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Journal article (peer-reviewed)abstract
- Iron (Fe) is an essential nutrient for microalgal metabolism. The low solubility of Fe in oxic aquatic environments can be a growth-limiting factor for phytoplankton. Synthetic chelating agents, such as ethylenediaminetetraacetic acid (EDTA), are used widely to maintain Fe in solution for microalgal cultivation. The non-biodegradable nature of EDTA, combined with sub-optimal bioavailability of Fe-EDTA complexes to microalgae, indicates opportunity to improve microalgal cultivation practices that amplify production efficiency and environmental compatibility. In the present study, the effects of four organic chelating ligands known to form readily bioavailable organic complexes with Fe in natural aquatic environments were investigated in relation to growth and biochemical composition of two marine microalgae grown as live feeds in shellfish hatcheries (Chaetoceros calcitrans and Tisochrysis lutea). Three saccharides, alginic acid (ALG), glucuronic acid (GLU), and dextran (DEX), as well as the siderophore desferrioxamine B (DFB), were compared to EDTA. Organic ligands characterized by weaker binding capacity for cationic metals (i.e., ALG, GLU, DEX) significantly improved microalgal growth and yields in laboratory-scale static batch cultures or bubbled photobioreactors. Maximal microalgal growth enhancement relative to the control (e.g., EDTA) was recorded for GLU, followed by ALG, with 20-35% increase in specific growth rate in the early stages of culture development of C. calcitrans and T. lutea. Substitution of EDTA with GLU resulted in a 27% increase in cellular omega 3-polyunsaturetd fatty acid content of C. calcitrans and doubled final cell yields. Enhanced microalgal culture performance is likely associated with increased intracellular Fe uptake efficiency combined with heterotrophic growth stimulated by the organic ligands. Based upon these results, we propose that replacement of EDTA with one of these organic metal-chelating ligands is an effective and easily implementable strategy to enhance the environmental compatibility of microalgal cultivation practices while also maximizing algal growth and enhancing the nutritional quality of marine microalgal species commonly cultured for live-feed applications in aquaculture.
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| 26. |
- Sauvage, Justine, et al.
(author)
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Effect of pluronic block polymers and N-acetylcysteine culture media additives on growth rate and fatty acid composition of six marine microalgae species
- 2021
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In: Applied Microbiology and Biotechnology. - : Springer Science and Business Media LLC. - 0175-7598 .- 1432-0614. ; 105, s. 2139-2156
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Journal article (peer-reviewed)abstract
- The efficiency of microalgal biomass production is a determining factor for the economic competitiveness of microalgae-based industries. N-acetylcysteine (NAC) and pluronic block polymers are two compounds of interest as novel culture media constituents because of their respective protective properties against oxidative stress and shear-stress-induced cell damage. Here we quantify the effect of NAC and two pluronic (F127 and F68) culture media additives upon the culture productivity of six marine microalgal species of relevance to the aquaculture industry (four diatoms-Chaetoceros calcitrans, Chaetoceros muelleri, Skeletonema costatum, and Thalassiosira pseudonana; two haptophytes-Tisochrysis lutea and Pavlova salina). Algal culture performance in response to the addition of NAC and pluronic, singly or combined, is dosage- and species-dependent. Combined NAC and pluronic F127 algal culture media additives resulted in specific growth rate increases of 38%, 16%, and 24% for C. calcitrans, C. muelleri, and P. salina, respectively. Enhanced culture productivity for strains belonging to the genus Chaetoceros was paired with an similar to 27% increase in stationary-phase cell density. For some of the species examined, culture media enrichments with NAC and pluronic resulted in increased omega-3-fatty acid content of the algal biomass. Larval development (i.e., growth and survival) of the Pacific oyster (Crassostrea gigas) was not changed when fed a mixture of microalgae grown in NAC- and F127-supplemented culture medium. Based upon these results, we propose that culture media enrichment with NAC and pluronic F127 is an effective and easily adopted approach to increase algal productivity and enhance the nutritional quality of marine microalgal strains commonly cultured for live-feed applications in aquaculture.
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| 27. |
- Vogeler, Susanne, et al.
(author)
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Bivalves are NO different: nitric oxide as negative regulator of metamorphosis in the Pacific oyster, Crassostrea gigas
- 2020
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In: BMC Developmental Biology. - : Springer Science and Business Media LLC. - 1471-213X. ; 20
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Journal article (peer-reviewed)abstract
- Nitric oxide (NO) is presumed to be a regulator of metamorphosis in many invertebrate species, and although NO pathways have been comparatively well-investigated in gastropods, annelids and crustaceans, there has been very limited research on the effects of NO on metamorphosis in bivalve shellfish. Results: In this paper, we investigate the effects of NO pathway inhibitors and NO donors on metamorphosis induction in larvae of the Pacific oyster, Crassostrea gigas. The nitric oxides synthase (NOS) inhibitors s-methylisothiourea hemisulfate salt (SMIS), aminoguanidine hemisulfate salt (AGH) and 7-nitroindazole (7-NI) induced metamorphosis at 75, 76 and 83% respectively, and operating in a concentration-dependent manner. Additional induction of up to 54% resulted from exposures to 1H-[1,2,4]Oxadiazole[4,3-a]quinoxalin-1-one (ODQ), an inhibitor of soluble guanylyl cyclase, with which NO interacts to catalyse the synthesis of cyclic guanosine monophosphate (cGMP). Conversely, high concentrations of the NO donor sodium nitroprusside dihydrate in combination with metamorphosis inducers epinephrine, MK-801 or SMIS, significantly decreased metamorphosis, although a potential harmful effect of excessive NO unrelated to metamorphosis pathway cannot be excluded. Expression of CgNOS also decreased in larvae after metamorphosis regardless of the inducers used, but intensified again post-metamorphosis in spat. Fluorescent detection of NO in competent larvae with DAF-FM diacetate and localisation of the oyster nitric oxide synthase CgNOS expression by in-situ hybridisation showed that NO occurs primarily in two key larval structures, the velum and foot. cGMP was also detected in the foot using immunofluorescent assays, and is potentially involved in the foot’s smooth muscle relaxation. Conclusion: Together, these results suggest that the NO pathway acts as a negative regulator of metamorphosis in Pacific oyster larvae, and that NO reduction induces metamorphosis by inhibiting swimming or crawling behaviour, in conjunction with a cascade of additional neuroendocrine downstream responses.
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| 28. |
- Vogeler, Susanne, et al.
(author)
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Cloning and characterisation of NMDA receptors in the Pacific oyster, Crassostrea gigas (Thunberg, 1793) in relation to metamorphosis and catecholamine synthesis
- 2021
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In: Developmental Biology. - : Elsevier BV. - 0012-1606 .- 1095-564X. ; 469, s. 144-59
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Journal article (peer-reviewed)abstract
- © 2020 Elsevier Inc. Bivalve metamorphosis is a developmental transition from a free-living larva to a benthic juvenile (spat), regulated by a complex interaction of neurotransmitters and neurohormones such as L-DOPA and epinephrine (catecholamine). We recently suggested an N-Methyl-D-aspartate (NMDA) receptor pathway as an additional and previously unknown regulator of bivalve metamorphosis. To explore this theory further, we successfully induced metamorphosis in the Pacific oyster, Crassostrea gigas, by exposing competent larvae to L-DOPA, epinephrine, MK-801 and ifenprodil. Subsequently, we cloned three NMDA receptor subunits CgNR1, CgNR2A and CgNR2B, with sequence analysis suggesting successful assembly of functional NMDA receptor complexes and binding to natural occurring agonists and the channel blocker MK-801. NMDA receptor subunits are expressed in competent larvae, during metamorphosis and in spat, but this expression is neither self-regulated nor regulated by catecholamines. In-situ hybridisation of CgNR1 in competent larvae identified NMDA receptor presence in the apical organ/cerebral ganglia area with a potential sensory function, and in the nervous network of the foot indicating an additional putative muscle regulatory function. Furthermore, phylogenetic analyses identified molluscan-specific gene expansions of key enzymes involved in catecholamine biosynthesis. However, exposure to MK-801 did not alter the expression of selected key enzymes, suggesting that NMDA receptors do not regulate the biosynthesis of catecholamines via gene expression.
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| 29. |
- Vogeler, Susanne, et al.
(author)
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Distribution of vitamin B12 in bivalve tissues: Investigations of larval and adult lifestages
- 2022
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In: Aquaculture. - : Elsevier BV. - 0044-8486. ; 561
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Journal article (peer-reviewed)abstract
- Shellfish, in particular bivalves, are an often-overlooked source of vitamin B12 (B12) in the human diet although they have significantly higher tissue levels of B12 than other animal meat or fish sources, including all vertebrates. However, the origins and key metabolic processes involving B12 in bivalves remain largely unknown. In this study, we examined the distribution of B12 in tissues of several adult Australian bivalve species and assessed hypotheses concerning their B12 utilisation and principal uptake, specifically whether it is derived from diet or gut microbiome. Pacific oysters, Crassostrea gigas, and Goolwa cockles, Plebidonax deltoides (‘pipis’), are both high in B12 (28.0–49.4 μg/100 g total per individual). Vitamin B12 tissue distribution, particularly in oysters, varied significantly, with higher amounts in the adductor muscle (44.0–96.7 μg/100 g), and other tissues, such as gonads, were relatively low (12.7–35.9 μg/100 g). In comparison, concentrations of B12 in the adductor muscle and roe of Southern Australian scallops, Pecten fumatus, were appreciably lower (3.4–10.8 μg/100 g). We also demonstrated that microalgal feed commonly grown in aquaculture can be supplemented directly with B12, resulting in an enriched feed. However, the B12-enriched diet did not transfer to a significant increase in oyster larval B12 concentrations, contradicting our theory that vitamin uptake through feed was a primary B12 source. Vitamin B12 concentrations across oyster larval life stages showed a significant decrease post metamorphosis, which indicates a higher utilisation of B12 during this life event. Our findings also provide insight into B12 uptake and tissue distribution in bivalve species, which can aid the aquaculture industry in promotion of bivalves as a valuable source of dietary B12 for human consumers, while also suggesting ways to optimise vitamin supplementation in bivalve hatchery production.
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| 30. |
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| 31. |
- Vogeler, Susanne, et al.
(author)
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Larval metamorphosis in four bivalve species in response to NMDA receptor ligands: The NMDA receptor pathway as potential regulator of bivalve transition to spat
- 2019
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In: Aquaculture. - : Elsevier BV. - 0044-8486. ; 511
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Journal article (peer-reviewed)abstract
- Over the last three decades, a variety of chemical inducers or disruptors for settlement and metamorphosis have been identified for species of clams, oysters, scallops, and mussels. Identifying inducers is important in shellfish aquaculture for increasing metamorphosis rates, and hence, spat (seed) production; however, it also has wider applications, such as in the development of marine anti-fouling agents. Previously, we have suggested the potential importance of an N-Methyl-D-aspartate (NMDA) receptor pathway in regulating bivalve metamorphosis based on preliminary work in Crassostrea gigas. In this study, we further this work by assessing the ability of several known vertebrate NMDA receptor antagonists (MK-801, ifenprodil and chlorpromazine) to induce metamorphosis in a range of bivalve species. In two oyster species (Crassostrea virginica, C. gigas) and two clam species (Mercenaria mercenaria, Mya arenaria) all three NMDA receptor antagonists induced metamorphosis, but with variability in optimal concentrations and effectiveness. Specifically, both clam species were highly responsive to the NMDA receptor antagonists, with M. mercenaria displaying up to 100% induction with both ifenprodil at 10−5 M and 10−6 M and chlorpromazine at 10−7 M to 10−5 M. There is very limited prior work on successful induction using neuroactive compounds for metamorphosis in the hard-shell clam, M. mercenaria, and no prior published work for the soft-shell clam, M. arenaria. Epinephrine and levodopa (L-DOPA), two widely used and effective inducers in Crassostrea species, also induced metamorphosis in both clam species with epinephrine at 10−4 M resulting in 44% and 75% metamorphosis and L-DOPA at 10−5 M resulting in 67% and 98% for M. arenaria and M. mercenaria, respectively. Co-exposures of L-DOPA or epinephrine in conjunction with NMDA receptor antagonists were conducted to identify putative interactions between the proposed NMDA receptor pathway and the dopaminergic or adrenergic pathways by which L-DOPA and epinephrine are believed to operate. In general, co-exposures demonstrated induction of metamorphosis similar or higher than the most effective single treatments. In experiments conducted in 2018 for both oyster species, epinephrine at 10−4 M in conjunction with ifenprodil at 10−6 M, significantly inhibited metamorphosis down to 4% from 12%. The percentage of larvae that underwent metamorphosis was similarly low in response to ifenprodil alone, 2% to 18% metamorphosis, whereas epinephrine alone had a positive inducing effect, 34% to 74% metamorphosis. Results are discussed in relation to the NMDA receptor pathway that appears to be acting independently of previously believed dopaminergic or adrenergic pathways in bivalves.
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| 32. |
- Vogeler, Susanne, et al.
(author)
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Phylogenetic analysis of the caspase family in bivalves: implications for programmed cell death, immune response and development
- 2021
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In: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 22:1
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Journal article (peer-reviewed)abstract
- Background Apoptosis is an important process for an organism’s innate immune system to respond to pathogens, while also allowing for cell differentiation and other essential life functions. Caspases are one of the key protease enzymes involved in the apoptotic process, however there is currently a very limited understanding of bivalve caspase diversity and function. Results In this work, we investigated the presence of caspase homologues using a combination of bioinformatics and phylogenetic analyses. We blasted the Crassostrea gigas genome for caspase homologues and identified 35 potential homologues in the addition to the already cloned 23 bivalve caspases. As such, we present information about the phylogenetic relationship of all identified bivalve caspases in relation to their homology to well-established vertebrate and invertebrate caspases. Our results reveal unexpected novelty and complexity in the bivalve caspase family. Notably, we were unable to identify direct homologues to the initiator caspase-9, a key-caspase in the vertebrate apoptotic pathway, inflammatory caspases (caspase-1, −4 or−5) or executioner caspases-3, −6, −7. We also explored the fact that bivalves appear to possess several unique homologues to the initiator caspase groups −2 and−8. Large expansions of caspase-3 like homologues (caspase-3A-C), caspase-3/7 group and caspase-3/7-like homologues were also identified, suggesting unusual roles of caspases with direct implications for our understanding of immune response in relation to common bivalve diseases. Furthermore, we assessed the gene expression of two initiator (Cg2A, Cg8B) and four executioner caspases (Cg3A, Cg3B, Cg3C, Cg3/7) in C. gigas late-larval development and during metamorphosis, indicating that caspase expression varies across the different developmental stages. Conclusion Our analysis provides the first overview of caspases across different bivalve species with essential new insights into caspase diversity, knowledge that can be used for further investigations into immune response to pathogens or regulation of developmental processes.
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