Hopp i havet med hoppekreps

Hoppekreps (Copepoda) inntar en nøkkelrolle i den marine næringskjeden, og har stor betydning som bindeledd mellom primærproduksjon og høyere trofiske nivåer. Til tross for dette er det fremdeles mange kunnskapshull knyttet til artsmangfold, taksonomi og utbredelse, spesielt om arter som lever like over eller nær bunnen (hyperbentos). Det er gjort svært få undersøkelser av hyperbentiske copepoder siden de omfattende arbeidene til G.O. Sars i perioden 1860–1928. Dette skyldes delvis at hyperbentos er vanskelig tilgjengelig, og at vi må bruke mange forskjellige metoder for å samle dem. Det er også en stor mangel på taksonomisk kompetanse. I dette prosjektet (HYPCOP) har vi som mål å kartlegge hoppekreps i hyperbentiske marine habitater fra norske havområder, inkludert hyperbentos i grunne kystområder og dype fjorder. Samtidig som vi bygger opp en viktig samling i museet som fremtidige forskere kan jobbe videre med, bygger vi også opp ny taksonomisk kompetanse på copepoder i norske fagmiljøer

Shrimps of the genus Periclimenes (Crustacea, Decapoda, Palaemonidae) associated with mushroom corals (Scleractinia, Fungiidae): Linking DNA barcodes to morphology

Most marine palaemonid shrimp species live in symbiosis with invertebrates of various phyla. These associations range from weak epibiosis to obligatory endosymbiosis and from restricted commensalism to semi-parasitism. On coral reefs, such symbiotic shrimps can contribute to the associated biodiversity of reef corals. Among the host taxa, mushroom corals (Cnidaria: Anthozoa: Fungiidae) are known to harbour various groups of symbionts, including shrimps. Some but not all of these associated species are host-specific. Because data on the host specificity of shrimps on mushroom corals are scarce, shrimp species of the genus Periclimenes were collected from mushroom corals during fieldwork in Lembeh Strait, North Sulawesi, Indonesia. Using molecular (COI barcoding gene) and morphological methods, three species of Periclimenes were identified: P. diversipes, P. watamuae and a species new to science, P. subcorallum sp. nov., described herein. Their host specificity was variable, with eight, three and two fungiid host records, respectively. It is concluded that shrimp species of the genus Periclimenes show much overlap in their host choice and that particular morphological traits in the host species appear to play a more important role than phylogenetic affinities within the host group.publishedVersio

On being the right size as an animal with plastids

Plastids typically reside in plant or algal cells—with one notable exception. There is one group of multicellular animals, sea slugs in the order Sacoglossa, members of which feed on siphonaceous algae. The slugs sequester the ingested plastids in the cytosol of cells in their digestive gland, giving the animals the color of leaves. In a few species of slugs, including members of the genus Elysia, the stolen plastids (kleptoplasts) can remain morphologically intact for weeks and months, surrounded by the animal cytosol, which is separated from the plastid stroma by only the inner and outer plastid membranes. The kleptoplasts of the Sacoglossa are the only case described so far in nature where plastids interface directly with the metazoan cytosol. That makes them interesting in their own right, but it has also led to the idea that it might someday be possible to engineer photosynthetic animals. Is that really possible? And if so, how big would the photosynthetic organs of such animals need to be? Here we provide two sets of calculations: one based on a best case scenario assuming that animals with kleptoplasts can be, on a per cm2 basis, as efficient at CO2 fixation as maize leaves, and one based on14 CO2 fixation rates measured in plastid-bearing sea slugs. We also tabulate an overview of the literature going back to 1970 reporting direct measurements or indirect estimates of the CO2 fixing capabilities of Sacoglossan slugs with plastids

A sea slug's guide to plastid symbiosis

Some 140 years ago sea slugs that contained chlorophyll-pigmented granules similar to those of plants were described. While we now understand that these “green granules” are plastids the slugs sequester from siphonaceous algae upon which they feed, surprisingly little is really known about the molecular details that underlie this one of a kind animal-plastid symbiosis. Kleptoplasts are stored in the cytosol of epithelial cells that form the slug’s digestive tubules, and one would guess that the stolen organelles are acquired for their ability to fix carbon, but studies have never really been able to prove that. We also do not know how the organelles are distinguished from the remaining food particles the slugs incorporate with their meal and that include algal mitochondria and nuclei. We know that the ability to store kleptoplasts long-term has evolved only a few times independently among hundreds of sacoglossan species, but we have no idea on what basis. Here we take a closer look at the history of sacoglossan research and discuss recent developments. We argue that, in order to understand what makes this symbiosis work, we will need to focus on the animal’s physiology just as much as we need to commence a detailed analysis of the plastids’ photobiology. Understanding kleptoplasty in sacoglossan slugs requires an unbiased multidisciplinary approach

Why it is time to look beyond algal genes in photosynthetic slugs

Eukaryotic organelles depend on nuclear genes to perpetuate their biochemical integrity. This is true for mitochondria in all eukaryotes and plastids in plants and algae. Then how do kleptoplasts, plastids that are sequestered by some sacoglossan sea slugs, survive in the animals' digestive gland cells in the absence of the algal nucleus encoding the vast majority of organellar proteins? For almost two decades, lateral gene transfer (LGT) from algae to slugs appeared to offer a solution, but RNA-seq analysis, later supported by genome sequencing of slug DNA, failed to find any evidence for such LGT events. Yet, isolated reports continue to be published and are readily discussed by the popular press and social media, making the data on LGT and its support for kleptoplast longevity appear controversial. However, when we take a sober look at the methods used, we realize that caution is warranted in how the results are interpreted. There is no evidence that the evolution of kleptoplasty in sea slugs involves LGT events. Based on what we know about photosystem maintenance in embryophyte plastids, we assume kleptoplasts depend on nuclear genes. However, studies have shown that some isolated algal plastids are, by nature, more robust than those of land plants. The evolution of kleptoplasty in green sea slugs involves many promising and unexplored phenomena, but there is no evidence that any of these require the expression of slug genes of algal origin

<strong><em>Hamodactylus macrophthalmus</em> spec. nov., a new coral-associated pontoniine shrimp (Decapoda, Caridea, Palaemonidae) from Indonesia</strong>

Fransen, Charles H. J. M., Rauch, Cessa (2013): Hamodactylus macrophthalmus spec. nov., a new coral-associated pontoniine shrimp (Decapoda, Caridea, Palaemonidae) from Indonesia. Zootaxa 3635 (3): 286-296, DOI: 10.11646/zootaxa.3635.3.

Integrative taxonomy reveals a cryptic species of the nudibranch genus Polycera (Polyceridae) in European waters

This work aimed to test whether the colour variability featured by the European nudibranch Polycera quadrilineata is consistent with the concept of a single polychromatic species or may hide multiple lineages. Samples from across the geographic range of P. quadrilineata together with representatives from worldwide species with a focus on Atlantic diversity, were gathered and studied using an integrative taxonomic approach. Morpho-anatomical characters were investigated by light and scanning electron microscopy. Bayesian molecular phylogenetics using MrBayes, the Automatic Barcode Gap Discovery species delimitation method, and haplotype network analysis using the PopArt software were employed to help delimit species using the mitochondrial gene cytochrome c oxidase subunit I (COI). The results supported the existence of a second species, here described and named Polycera norvegica sp. nov., only known from Norway where it is sympatric with P. quadrilineata. The COI uncorrected p-genetic distance between the two species was estimated at 9.6–12.4%. Polycera norvegica sp. nov. differs by exhibiting a black dotted or patchy dotted pattern occasionally with more or less defined orange/brown patches, but never black continuous or dashed stripes as in P. quadrilineata. The two species share a common colouration with a whitish base and yellow/orange tubercles. Anatomically, P. norvegica sp. nov. has a weaker labial cuticle, a smaller radula with fewer rows, and only four marginal teeth, a reproductive system with a single lobed bursa copulatrix, shorter reproductive ducts, and a penis armed with two kinds of spines: needle-like and hook-shaped penile spines

The ability to incorporate functional plastids by the sea slug Elysia viridis is governed by its food source

Functional kleptoplasty in sacoglossan sea slugs is among the most curious photosynthetic associations known. One member of these marine molluscs, Elysia viridis, is known to incorporate plastids from a variety of different algae food sources, but with apparently different outcomes and differences in the time span of the retention of functional kleptoplasts. While it was previously shown that kleptoplasts that stem from Codium tomentosum are kept functional for several weeks (long-term retention, LtR), those that stem from Bryopsis hypnoides or Cladophora rupestris are thought to be of limited use regarding photosynthetic capacity (short-term retention, StR). This is important, because it touches upon the popular yet controversial question of how important photosynthesis is for the thriving of these slugs. The aim of the present study was to determine to what degree the plastid source determines retention time. We, therefore, compared E. viridis feeding on either Cladophora sp. or B. hypnoides. We show that kleptoplasts of B. hypnoides incorporate 14CO2, but with rapidly declining efficiency throughout the first week of starvation, while the plastids of Cladophora sp. are, surprisingly, not incorporated to begin with. The radulae of the different samples showed adjustment to the food source, and when feeding on Cladophora sp., E. viridis survived under laboratory conditions under both starvation and non-starvation conditions. Our results demonstrate that (i) the ability to incorporate plastids by E. viridis differs between the food sources B. hypnoides and Cladophora sp., and (ii) photosynthetic active kleptoplasts are not an inevitable requirement for survival