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Relationship between abundance of specialist marine herbivores and their food sources is poorly known because these herbivores are relatively rare in marine systems. The relationship between the cryptic sea slug Elysia pusilla (Bergh, 1872) and its host alga, Halimeda macroloba Decaisne, was evaluated in terms of spatial association and habitat utilization in a tropical algal meadow in southern Thailand that exclusively comprised of H. macroloba. The density of H. macroloba and of E. pusilla egg masses varied temporally throughout the sampling period, but temporal variation was not detected in the density of E. pusilla individuals, which was generally low with a maximum of 4 individuals per 400 cm². Analysis suggests that the occurrence of the slug and its egg masses might be determined by the availability of the algal host. The slug was more likely to be observed in dense patches of algae that which offered a large total algal surface area. Occurrence of the slug was also higher when the algae were abundant. The numbers of slugs, egg masses and grazing marks were higher on mature thalli, which have larger surface areas than younger thalli. Egg masses and grazing marks were observed more often on segments at terminal positions on thalli. According to previous works, these segments contain low levels of accumulated calcium carbonate and high levels of secondary metabolites, which are sequestered by the slug and used to deter predators. The findings provide an insight into the life history of E. pusilla and variations in a natural population which that were previously little known. [ABSTRACT FROM AUTHOR]

Sacoglossan sea slugs feed by suctorially consuming siphonaceous green algae. Most sacoglossan species are feeding specialists, but the Caribbean coral reef-dwelling Elysia crispata is polyphagous and sequesters chloroplasts from multiple algal species into cells lining its digestive diverticulum for use in photosynthesis. We have used sequences of the chloroplast-encoded rbc L gene to compare the chloroplast donor algae in five populations of E. crispata from various Caribbean locations. We found that E. crispata utilizes more algal species than was previously known, including some algae previously not reported as present in the region. In addition, slugs from each location had unique chloroplast arrays with little overlap, except that all locations had slugs feeding on algae within the genus Bryopsis. This variation in diet between locations suggests that the slugs may be exhibiting local adaptation in their dietary choices, and it highlights ecological differences between the Caribbean-wide reef-dwelling ecotypes and the mangrove lagoon ecotypes found in the Florida Keys. [ABSTRACT FROM AUTHOR]

Bioassay-guided fractionation of the CHCl 3 /MeOH extract of Elysia ornata mucus showing antifungal activity led us to isolate kahalalide F (KF) along with two unprecedented related peptides. The structures of kahalalide Z 1 ( 1 ) and kahalalide Z 2 ( 2 ), were established by combination of NMR spectroscopic and mass spectrometry data, also including Marfey amino acid analysis. Compounds 1 and 2 displayed significant antimicrobial properties against several fungal pathogens infesting economically important plants, food, and fish, and were also found to inhibit the in vitro growth of a series of cancer cell lines in a comparable fashion with KF. [ABSTRACT FROM AUTHOR]

The phenomenon of the uptake, intracellular sequestration, and subsequent usage of algal chloroplasts by the digestive cells of many species of sacoglossan sea slugs, currently called kleptoplasty, has been of considerable interest since its discovery in the 1960s. While a large body of literature reported that captured chloroplasts were photosynthetically active inside slug cells and that plastid longevity in some species might be the result of the horizontal transfer of functional algal nuclear genes into the slug genome, a few recent studies have called the older results into question. Here, we have reviewed the literature and showed that while kleptoplasty occurs in many slug species and almost all derive benefit from kleptoplast photosynthesis, the slug adaptations to maintain the chloroplasts differ from species to species. These adaptations range from behavioral to molecular, including gene transfer, in a variety of combinations. [ABSTRACT FROM AUTHOR]

Introduction The Mediterranean sacoglossan Elysia timida is one of the few sea slug species with the ability to sequester chloroplasts from its food algae and to subsequently store them in a functional state in the digestive gland cells for more than a month, during which time the plastids retain high photosynthetic activity (= long-term retention). Adult E. timida have been described to feed on the unicellular alga Acetabularia acetabulum in their natural environment. The suitability of E. timida as a laboratory model culture system including its food source was studied. Results In contrast to the literature reporting that juvenile E. timida feed on Cladophora dalmatica first, and later on switch to the adult diet A. acetabulum, the juveniles in this study fed directly on A. acetabulum (young, non-calcified stalks); they did not feed on the various Cladophora spp. (collected from the sea or laboratory culture) offered. This could possibly hint to cryptic speciation with no clear morphological differences, but incipient ecological differentiation. Transmission electron microscopy of chloroplasts from A. acetabulum after initial intake by juvenile E. timida showed different states of degradation - in conglomerations or singularly - and fragments of phagosome membranes, but differed from kleptoplast images of C. dalmatica in juvenile E. timida from the literature. Based on the finding that the whole life cycle of E. timida can be completed with A. acetabulum as the sole food source, a laboratory culture system was established. An experiment with PAMfluorometry showed that cultured E. timida are also able to store chloroplasts in long-term retention from Acetabularia peniculus, which stems from the Indo-Pacific and is not abundant in the natural environment of E. timida. Variations between three experiment groups indicated potential influences of temperature on photosynthetic capacities. Conclusions E. timida is a viable laboratory model system to study photosynthesis in incorporated chloroplasts (kleptoplasts). Capacities of chloroplast incorporation in E. timida were investigated in a closed laboratory culture system with two different chloroplast donors and over extended time periods about threefold longer than previously reported. [ABSTRACT FROM AUTHOR]

Highlights: [•] The chemistry of the sacoglossan mollusc Elysia patagonica has been investigated for the first time. [•] A new γ-pyrone hydroperoxyl polypropionate has been isolated and characterized. [•] This finding is in agreement with the literature data on taxonomically related elysioidean sacoglossans. [ABSTRACT FROM AUTHOR]

The sacoglossans are small sea slugs in the Heterobranchia. In this study, mitochondrial genome of a sacoglossan sea slug,Elysia ornata(Swainson, 1840) is analyzed and phylogenetic tree of the species in the Heterobranchia is reconstructed based on amino acid sequences of mitochondrial protein coding genes. The phylogenetic relationship analysis shows thatE. ornatabelongs to the monophyletic Sacoglossa in the Heterobranchia and the Sacoglossa shows sister group relationship with a lineage including Anaspidea and Siphonarioidea. This is the fourth record for the mitochondrial genome of sacoglossan sea slugs. [ABSTRACT FROM PUBLISHER]

A summary is presented of an article published online at http://dx.doi.org/10.1126/science.aaw6732 studying toxin production in the Hawaiian marine algae Bryopsis sp. and the mollusk Elysia rufescens which feeds off of the algae and uses chemical sequestration to indirectly acquire kahalalides from the algae.

This paper presents the first report of Elysia grandifolia Kelaart, 1858 in the Iskenderun Bay (the northeast end of the Levantine Sea (EM), the southeastern coast of Turkey). It is also, the second record of E. grandifolia in the Turkish Levantine coast. [ABSTRACT FROM AUTHOR]