A Model of F-actin Organization in Granuloreticulopodia in Foraminifera: Morphogenetic and Evolutionary Implications from Novel Fluorescent and Polarised Light Observations.

Foraminifera are a group of mostly marine protists that form highly dynamic granular pseudopodia. Recent live experiments on foraminifera labelled with SiR-actin show that F-actin structures are involved in the morphogenesis of granuloreticulopodia and that pseudopodia contain small, motile granules referred to as SiR-actin-labelled granules (ALGs). They may either represent staining artifacts or an unusual form of organisation of actin filaments. To address this problem, we performed double staining of F-actin in fixed specimens of foraminifera using two fluorescent probes (SiR-actin and Phalloidin Atto 488) and analysed the level of co-localisation of their fluorescent signals. Additionally, we performed observations in polarised light to identify birefringence. The images obtained demonstrate similar staining patterns with both probes and birefringence in areas showing intensive fluorescence, thus, ALGs can no longer be considered as staining artifacts. They represent naturally occurring granular structures that contain F-actin and/or are actin-coated. ALGs likely contain F-actin that may play a role in endo-/exocytosis, pseudopodial movement, and/or in intracellular transport. We present a model, explaining their formation and possible functions in relation to other subcellular components. ALGs most likely consist of the adaptation involved in the morphogenesis of granular pseudopodia that predates in phylogeny the occurrence of the shell in foraminifera.

What's left in the tank? Identification of non-ascribed aquarium's coral collections with DNA barcodes as part of an integrated diagnostic approach.

The unprecedented threats to coral reef ecosystems from global climate change require an urgent response from the aquarium community, which is becoming an increasingly vital coral conservation resource. Unfortunately, many hermatypic corals in aquaria are not identified to species level, which hinders assessment of their conservation significance. Traditional methods of species identification using morphology can be challenging, especially to non-taxonomists. DNA barcoding is an option for species identification of Scleractinian corals, especially when used in concert with morphology-based assessment. This study uses DNA barcodes to try to identify aquarium specimens of the diverse reef-forming genus Acropora from 127 samples. We identified to our best current knowledge, to species name 44% of the analysed samples and provided provisional identification for 80% of them (101/127, in the form of a list of species names with associate confidence values). We highlighted a sampling bias in public nucleotide sequences repertories (e.g. GenBank) towards more charismatic and more studied species, even inside a well-studied genus like Acropora. In addition, we showed a potential "single observer" effect with over a quarter of the reference sequences used for these identifications coming from the same study. We propose the use of barcoding and query matching as an additional tool for taxonomic experts and general aquarists, as an additional tool to increase their chances of making high confidence species-level identifications. We produce a standardised and easily repeatable methodology to increase the capacity of aquariums and other facilities to assess non-ascribed species, emphasising the value of integrating this approach with morphological identification optimising usage of authoritative identification guides and expert opinion. Supplementary Information: The online version contains supplementary material available at 10.1007/s12686-021-01250-3.

The World Coral Conservatory (WCC): A Noah's ark for corals to support survival of reef ecosystems.

Global change causes widespread decline of coral reefs. In order to counter the anticipated disappearance of coral reefs by the end of this century, many initiatives are emerging, including creation of marine protected areas (MPAs), reef restoration projects, and assisted evolution initiatives. Such efforts, although critically important, are locally constrained. We propose to build a "Noah's Ark" biological repository for corals that taps into the network of the world's public aquaria and coral reef scientists. Public aquaria will serve not only as a reservoir for the purpose of conservation, restoration, and research of reef-building corals but also as a laboratory for the implementation of operations for the selection of stress-resilient and resistant genotypes. The proposed project will provide a global dimension to coral reef education and protection as a result of the involvement of a network of public and private aquaria.

Form and function of F-actin during biomineralization revealed from live experiments on foraminifera.

Although the emergence of complex biomineralized forms has been investigated for over a century, still little is known on how single cells control morphology of skeletal structures, such as frustules, shells, spicules, or scales. We have run experiments on the shell formation in foraminifera, unicellular, mainly marine organisms that can build shells by successive additions of chambers. We used live imaging to discover that all stages of chamber/shell formation are controlled by dedicated actin-driven pseudopodial structures. Successive reorganization of an F-actin meshwork, associated with microtubular structures, is actively involved in formation of protective envelope, followed by dynamic scaffolding of chamber morphology. Then lamellar dynamic templates create a confined space and control mineralization separated from seawater. These observations exclude extracellular calcification assumed in selected foraminiferal clades, and instead suggest a semiintracellular biomineralization pattern known from other unicellular calcifying and silicifying organisms. These results give a challenging prospect to decipher the vital effect on geochemical proxies applied to paleoceanographic reconstructions. They have further implications for understanding multiscale complexity of biomineralization and show a prospect for material science applications.

Contraception within an elasmobranch captive breeding programme: a case report on the eagle ray Aetobatus ocellatus using gonadotrophin-releasing hormone (GnRH) agonist deslorelin (Suprelorin).

This study describes the first case of contraception within a captive elasmobranch breeding programme where an implant of Suprelorin, containing a long-acting gonadotrophin-releasing hormone (GnRH) analogue Deslorelin, was implanted in an eagle ray Aetobatus ocellatus, which successfully halted breeding.

Epizoic acoelomorph flatworms impair zooplankton feeding by the scleractinian coral Galaxea fascicularis.

Many scleractinian coral species host epizoic acoelomorph flatworms, both in aquaculture and in situ. These symbiotic flatworms may impair coral growth and health through light-shading, mucus removal and disruption of heterotrophic feeding. To quantify the effect of epizoic flatworms on zooplankton feeding, we conducted video analyses of single polyps of Galaxea fascicularis (Linnaeus 1767) grazing on Artemia nauplii in the presence and absence of symbiotic flatworms. 18S DNA analysis revealed that flatworms inhabiting G. fascicularis belonged to the genus Waminoa (Convolutidae), which were hosted at a density of 3.6±0.4 individuals polyp(-1). Polyps hosting flatworms exhibited prey capture rates of 2.2±2.5, 3.4±4.5 and 2.7±3.4 nauplii polyp(-1) 30 min(-1) at prey concentrations of 250, 500 and 1,000 nauplii L(-1), respectively. Polyps that had their flatworms removed displayed prey capture rates of 2.7±1.6, 4.8±4.1 and 16.9±10.3 nauplii polyp(-1) 30 min(-1). Significant main and interactive effects of flatworm presence and ambient prey concentration were found, reflected by the fact that flatworms significantly impaired host feeding rates at the highest prey density of 1,000 nauplii L(-1). In addition, flatworms displayed kleptoparasitism, removing between 0.1±0.3 and 0.6±1.1 nauplii 30 min(-1) from the oral disc of their host, or 5.3±3.3 to 50.0±2.1% of prey acquired by the coral. We suggest classifying the coral-associated Waminoa sp. as an epizoic parasite, as its presence may negatively affect growth and health of the host.

Intoxication following minor stabs from the spines of a porcupine fish.

We report an unusual intoxication by tetrodotoxin (TTX). A curator of an aquarium sustained minor punctures in his finger from the spines of a porcupine fish during an autopsy of a dead porcupine fish. He developed paresthesias, numbness, paresis, dizziness and headache. The death of the fish might have caused some autolysis, leading to increased availability of TTX. In combination with direct contact with the organ fluids, this probably led to TTX exposure via minor wounds.