scholarly journals Bacterial Nucleobases Synergistically Induce Larval Settlement and Metamorphosis in the Invasive MusselMytilopsis sallei

2019 ◽  
Vol 85 (16) ◽  
Author(s):  
Jian He ◽  
Qi Dai ◽  
Yuxuan Qi ◽  
Pei Su ◽  
Miaoqin Huang ◽  
...  
Keyword(s):  
Marine Invertebrates ◽  
Larval Settlement ◽  
Aquatic Systems ◽  
Substrate Selection ◽  
Content Type ◽  
Dreissenid Mussels ◽  
Settlement And Metamorphosis ◽  
Environmental Bacteria ◽  
Fouling Organisms ◽  
Chemical Mediators

ABSTRACTMarine bacterial biofilms have long been recognized as potential inducers of larval settlement and metamorphosis in marine invertebrates, but few chemical cues from bacteria have been identified. Here, we show that larval settlement and metamorphosis of an invasive fouling mussel,Mytilopsis sallei, could be induced by biofilms of bacteria isolated from its adult shells and other substrates from the natural environment. One of the strains isolated,Vibrio owensiiMS-9, showed strong inducing activity which was attributed to the release of a mixture of nucleobases including uracil, thymine, xanthine, hypoxanthine, and guanine into seawater. In particular, the synergistic effect of hypoxanthine and guanine was sufficient for the inducing activity ofV. owensiiMS-9. The presence of two or three other nucleobases could enhance, to some extent, the activity of the mixture of hypoxanthine and guanine. Furthermore, we determined that bacteria producing higher concentrations of nucleobases were more likely to induce larval settlement and metamorphosis ofM. salleithan were bacteria producing lower concentrations of nucleobases. The present study demonstrates that bacterial nucleobases play an important role in larval settlement and metamorphosis of marine invertebrates. This provides new insights into our understanding of the role of environmental bacteria in the colonization and aggregation of invasive fouling organisms and of the metabolites used as chemical mediators in cross-kingdom communication within aquatic systems.IMPORTANCEInvasive species are an increasingly serious problem globally. In aquatic ecosystems, invasive dreissenid mussels are well-known ecological and economic pests because they appear to effortlessly invade new environments and foul submerged structures with high-density aggregations. To efficiently control exotic mussel recruitment and colonization, the need to investigate the mechanisms of substrate selection for larval settlement and metamorphosis is apparent. Our work is one of very few to experimentally demonstrate that compounds produced by environmental bacteria play an important role in larval settlement and metamorphosis in marine invertebrates. Additionally, this study demonstrates that bacterial nucleobases can be used as chemical mediators in cross-kingdom communication within aquatic systems, which will enhance our understanding of how microbes induce larval settlement and metamorphosis of dreissenid mussels, and it furthermore may allow the development of new methods for application in antifouling.

scholarly journals Bacterial symbionts in animal development: arginine biosynthesis complementation enables larval settlement in a marine sponge

2020 ◽  
Author(s):  
Hao Song ◽  
Olivia H Hewitt ◽  
Sandie M Degnan
Keyword(s):  
Nitric Oxide ◽  
Marine Sponge ◽  
Marine Invertebrates ◽  
Sea Water ◽  
Larval Settlement ◽  
Critical Role ◽  
Bacterial Symbionts ◽  
Animal Phyla ◽  
Settlement And Metamorphosis ◽  
Oxide Synthase

SUMMARYLarval settlement and metamorphosis are regulated by nitric oxide (NO) signalling in a wide diversity of marine invertebrates (1-10). It is surprising, then, that in most invertebrates, the substrate for NO synthesis – arginine – cannot be biosynthesized but instead must be exogenously sourced (11). In the sponge Amphimedon queenslandica, vertically-inherited proteobacterial symbionts in the larva are able to biosynthesize arginine (12,13). Here we test the hypothesis that symbionts might provide arginine to the sponge host so that nitric oxide synthase expressed in the larva can produce NO, which induces metamorphosis (8), and the byproduct citrulline (Fig. 1). First, we find support for an arginine-citrulline biosynthetic loop in this sponge larval holobiont using stable isotope tracing. In symbionts, incorporated 13C-citrulline decreases as 13C-arginine increases, consistent with the use of exogenous citrulline for arginine synthesis. In contrast, 13C-citrulline accumulates in larvae as 13C-arginine decreases, demonstrating the uptake of exogenous arginine and its conversion to NO and citrulline. Second, we show that while Amphimedon larvae can derive arginine directly from seawater, normal settlement and metamorphosis can occur in artificial sea water lacking arginine. Together, these results support holobiont complementation of the arginine-citrulline loop and NO biosynthesis in Amphimedon larvae, suggesting a critical role for bacterial symbionts in the development of this marine sponge. Given that NO regulates settlement and metamorphosis in diverse animal phyla (1-10) and arginine is procured externally in most animals (11), we propose that symbionts may play a equally critical regulatory role in this essential life cycle transition in other metazoans.

scholarly journals Gene knockdown via electroporation of short hairpin RNAs in embryos of the marine hydroid Hydractinia symbiolongicarpus

2020 ◽  
Author(s):  
Gonzalo Quiroga-Artigas ◽  
Alexandrea Duscher ◽  
Katelyn Lundquist ◽  
Justin Waletich ◽  
Christine E. Schnitzler
Keyword(s):  
Gene Function ◽  
Marine Invertebrates ◽  
Larval Settlement ◽  
Endogenous Gene ◽  
Successful Model ◽  
Hydractinia Symbiolongicarpus ◽  
Settlement And Metamorphosis ◽  
Short Hairpin ◽  
Visual Confirmation ◽  
Short Hairpin Rnas

AbstractPerforming gene function analyses in a broad range of research organisms is crucial for understanding the biological functions of genes and their evolution. Recent studies have shown that short hairpin RNAs (shRNAs) can induce gene-specific knockdowns in two cnidarian species. We have developed a detailed, straightforward, and scalable method to deliver shRNAs into fertilized eggs of the hydrozoan cnidarian Hydractinia symbiolongicarpus via electroporation, yielding gene-targeted knockdowns that can be assessed throughout embryogenesis, larval settlement, and metamorphosis. Our electroporation protocol allows for the transfection of shRNAs into hundreds of fertilized H.symbiolongicarpus eggs simultaneously with minimal embryo death and no long-term harmful consequences on the developing animals. We show RT-qPCR and detailed phenotypic evidence of our method successfully inducing significant knockdowns of an exogenous gene (eGFP) and an endogenous gene (Nanos2). We also provide visual confirmation of successful shRNA transfection inside embryos through electroporation. This is the first time that electroporation as a delivery system has been developed for Hydractinia. Our detailed protocol for electroporation of shRNAs in H. symbiolongicarpus embryos constitutes an important experimental resource for the hydrozoan community while also serving as a successful model for the development of similar methods for interrogating gene function in other marine invertebrates.

I Feel That! Fluid Dynamics and Sensory Aspects of Larval Settlement across Scales

2018 ◽  
Keyword(s):  
Fluid Dynamics ◽  
Marine Invertebrates ◽  
Larval Settlement ◽  
External Environment ◽  
Life Cycles ◽  
Decision Making Process ◽  
Larval Biology ◽  
Sea Floor ◽  
External Cues ◽  
Juvenile Habitat

A commonality among oceanic life cycles is a process known as settlement, where dispersing propagules transition to the sea floor. For many marine invertebrates, this transition is irreversible, and therefore involves a crucial decision-making process through which larvae evaluate their juvenile habitat-to-be. In this chapter, we consider aspects of the external environment that could influence successful settlement. Specifically, we discuss water flow across scales, and how larvae can engage behaviors to influence where ocean currents take them, and enhance the likelihood of their being carried toward suitable settlement locations. Next, we consider what senses larvae utilize to evaluate their external environment and properly time such behavioral modifications, and settlement generally. We hypothesize that larvae integrate these various external cues in a hierarchical fashion, with differing arrangements being employed across ontogeny and among species. We conclude with a brief discussion of the future promises of larval biology, ecology, and evolution.

scholarly journals Substrate Selection of Ascidian Larva: Wettability and Nano-Structures

2021 ◽  
Vol 9 (6) ◽  
pp. 634
Author(s):  
Euichi Hirose ◽  
Noburu Sensui
Keyword(s):  
The Body ◽  
Substrate Selection ◽  
Artificial Structures ◽  
Substrate Preferences ◽  
Nano Structures ◽  
Hydrophobic Materials ◽  
Faunal Communities ◽  
Adhesive Organs ◽  
Fouling Organisms ◽  
Selection Of

Ascidians are marine sessile chordates that comprise one of the major benthic animal groups in marine ecosystems. They sometimes cause biofouling problems on artificial structures underwater, and non-indigenous, invasive ascidian species can potentially and seriously alter native faunal communities. Ascidian larvae are usually tadpole-shaped, negatively phototactic, and adhere on substrates by secreting a glue from their adhesive organs. Although larvae often prefer hydrophobic surfaces, such as a silicone rubber, for settlement, hydrophobic materials are often used to reduce occurrence of fouling organisms on artificial structures. This inconsistency may indicate that an attractive surface for larvae is not always suitable for settlement. Micro-scale structures or roughness may enhance the settlement of ascidian larvae, but settlement is significantly reduced by a nano-scale nipple array (or moth-eye structure), suggesting functional properties of similar structures found on the body surfaces of various invertebrates. The substrate preferences of larvae should be one of the important bases in considering measures against biofouling, and this review also discusses the potential uses of materials to safely reduce the impacts of invasive species.

scholarly journals ECOLOGÍA QUÍMICA DE LAS ESPONJAS EXCAVADORAS CLIONA APRICA, C. CARIBBAEA, C. DELITRIX Y C. TENUIS

2016 ◽  
Vol 34 ◽  
Author(s):  
Andia Chaves Fonnegra ◽  
Mateo López Victoria ◽  
Fernando Parra Velandia ◽  
Sven Zea
Keyword(s):  
Larval Settlement ◽  
Coral Tissue ◽  
Live Coral ◽  
Stegastes Partitus ◽  
Excavating Sponges ◽  
Natural Concentration ◽  
Experimental Media ◽  
Organic Extracts ◽  
Fouling Organisms ◽  
San Andres

The Caribbean encrusting and excavating sponges Cliona aprica, C. caribbaea, C. delitrix and C. tenuis (Porifera, Hadromerida, Clionaidae), aggresively undermine and displace live coral tissue. At San Andrés island and Islas del Rosario (Colombian Caribbean), in all 145 observed cases of direct contact of the sponges C. aprica, C. caribbaea and C. tenuis with 17 coral species, corals showed unhealthy signs in their tissue. It was also noticed that the surface of these sponges is colonized by few organisms and that they are rarely preyed upon. To establish the possible use of chemical substances by these sponges in competition for space with corals (allelopathy), as inhibitors of larval settlement (antifouling), and as feeding deterrents against generalist fish (antipredatory), the activity of crude organic extracts was experimentally evaluated. Extracts were prepared in methanol and 1:2 metanol:dichloromethane and incorporated in experimental media at the natural concentration within the sponges. Using an unpublished method being developed by J. Pawlik (University of North Caroline at Wilmington) and M. Ilan (Tel Aviv University), PhytagelTM disks with crude extracts of each of the four sponge species, placed on the coral Montastrea cavernosa, produced a greater degree of polyp mortality than control gels without extract. Gels with extracts of the sponges C. aprica and C. caribbaea + C. tenuis, served in Petri dishes and used as substratum in the field, inhibited significantly the settlement of fouling organisms, in comparison to control gels. In laboratory trials, wheat flour pellets with extracts C. delitrix and C. caribbaea + C. tenuis were significantly rejected by the omnivore reef damselfish, Stegastes partitus, whereas pellets with extract of C. aprica did not deter feeding. These results suggest that substances present in the crude organic extracts of these sponges may be responsible in part for their ability to compete for reef substrata and to defend themselves from potential aggressors.

scholarly journals Evolution of IncA/CblaCMY-2-Carrying Plasmids by Acquisition of theblaNDM-1Carbapenemase Gene

2011 ◽  
Vol 56 (2) ◽  
pp. 783-786 ◽  
Author(s):  
Alessandra Carattoli ◽  
Laura Villa ◽  
Laurent Poirel ◽  
Rémy A. Bonnin ◽  
Patrice Nordmann
Keyword(s):  
Host Range ◽  
Large Scale ◽  
The United States ◽  
Broad Host Range ◽  
New Delhi ◽  
Yersinia Ruckeri ◽  
Content Type ◽  
Photobacterium Damselae ◽  
Environmental Bacteria ◽  
Broad Host Range Plasmids

ABSTRACTTheblaNDM-1gene has been reported to be often located on broad-host-range plasmids of the IncA/C type in clinical but also environmental bacteria recovered from the New Delhi, India, area. IncA/C-type plasmids are the main vehicles for the spread of the cephalosporinase geneblaCMY-2, frequently identified in the United States, Canada, and Europe. In this study, we completed the sequence of IncA/C plasmid pNDM-KN carrying theblaNDM-1gene, recovered from aKlebsiella pneumoniaeisolate from Kenya. This sequence was compared with those of three IncA/C-type reference plasmids fromEscherichia coli,Yersinia ruckeri, andPhotobacterium damselae. Comparative analysis showed that theblaNDM-1gene was located on a widely diffused plasmid scaffold known to be responsible for the spread ofblaCMY-2-like genes and consequently for resistance to broad-spectrum cephalosporins. Considering that IncA/C plasmids possess a broad host range, this scaffold might support a large-scale diffusion of theblaNDM-1gene among Gram-negative rods.

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