Granuloside, A Unique Linear Homosesterterpene from the Antarctic Nudibranch Charcotia granulosa

A new homosesterterpene with a unique linear skeleton, named granuloside (<b>1</b>), has been fully characterized from the Antarctic nudibranch Charcotia granulosa Vayssière, 1906 (Mollusca: Gastropoda). The planar structure of <b>1</b> was determined by extensive spectroscopic techniques on the methyl derivatives (<b>1a</b> and <b>1b</b>), and the <i>R</i> absolute configuration at C-4 is suggested by comparison of experimental and calculated ECD spectra of <b>1b</b>. Granuloside (<b>1</b>) is the first linear homosesterterpene skeleton ever reported and, despite the low molecular complexity, its chemical structure poses many questions about its biogenesis and origin in the nudibranch

Metabolites from the Sea Hare <i>Aplysia fasciata</i>

Examination of the digestive and hermaphroditic glands’ organic extract of the sea hare Aplysia fasciata yielded 16 metabolites, including eight sesquiterpenes, three diterpenes, and five C15-acetogenins. Among them, three sesquiterpenes, 6-hydroxy-1-brasilene (1), epibrasilenol acetate (2), and 6-epi-β-snyderol (3), one acetogenin, (3Z,9Z)-7-chloro-6-hydroxy-12-oxo-pentadeca-3,9-dien-1-yne (4), and one diterpene, 16-acetoxy-15-bromo-7-hydroxy-9(11)-parguerene (5), are new natural products. The structure elucidation and the assignment of the relative configurations of the isolated natural products were established on the basis of extensive analyses of their spectroscopic data (NMR, MS, IR)

Illudalane Sesquiterpenoids of the Alcyopterosin Series from the Antarctic Marine Soft Coral <i>Alcyonium grandis</i>

Chemical investigation of the lipophilic extract of the Antarctic soft coral Alcyonium grandis led us to the finding of nine unreported sesquiterpenoids, 2−10. These molecules are members of the illudalane class and in particular belong to the group of alcyopterosins, illudalanes isolated from marine organisms. The structures of 2−10 were determined by interpretation of spectroscopic data. Repellency experiments conducted using the omnivorous Antarctic sea star Odontaster validus revealed a strong activity in the lipophilic extract of A. grandis against predation

Differential characters among <i>D</i>. <i>carinova</i> Moles, Avila & Wägele n. sp. and <i>D</i>. <i>antarctica</i>.

Differential characters among D. carinova Moles, Avila & Wägele n. sp. and D. antarctica.</p

Photographs of <i>D</i>. <i>antarctica</i> (left column: A,C,E,G) and <i>D</i>. <i>carinova</i> Moles, Avila & Wägele n. sp. (right column: B,D,F,H); specimens subjected to micro-CT reconstruction.

<p><b>A</b> Live animal, where most of the cerata were lost; close up of the cerata. <b>B</b> Live picture right after collection, showing the <i>D</i>. <i>carinova</i> n. sp. spawning on top of the gorgonian <i>Primnoisis antarctica</i> (Isididae). <b>C</b>–<b>D</b> Lateral and dorsal view of the preserved animals. <b>E</b>–<b>F</b> Ventral view of the preserved animals. <b>G</b>–<b>H</b> Lateral view of the preserved egg masses.</p

Scanning electron micrographs (SEM) of the radular teeth of <i>D</i>. <i>antarctica</i>.

<p>Scanning electron micrographs (SEM) of the radular teeth of <i>D</i>. <i>antarctica</i>.</p

The End of the Cold Loneliness: 3D Comparison between <i>Doto antarctica</i> and a New Sympatric Species of <i>Doto</i> (Heterobranchia: Nudibranchia)

<div><p>Although several studies are devoted to determining the diversity of Antarctic heterobranch sea slugs, new species are still being discovered. Among nudibranchs, <i>Doto antarctica</i> Eliot, 1907 is the single species of this genus described from Antarctica hitherto, the type locality being the Ross Sea. <i>Doto antarctica</i> was described mainly using external features. During our Antarctic research on marine benthic invertebrates, we found <i>D</i>. <i>antarctica</i> in the Weddell Sea and Bouvet Island, suggesting a circumpolar distribution. Species affiliation is herein supported by molecular analyses using cytochrome <i>c</i> oxidase subunit I, 16S rRNA, and histone H3 markers. We redescribe <i>D</i>. <i>antarctica</i> using histology, micro-computed tomography (micro-CT), and 3D-reconstruction of the internal organs. Moreover, we describe a new, sympatric species, namely <i>D</i>. <i>carinova</i> Moles, Avila & Wägele n. sp., and provide an anatomical comparison between the two Antarctic <i>Doto</i> species. Egg masses in both species are also described here for the first time. We demonstrate that micro-CT is a useful tool for non-destructive anatomical description of valuable specimens. Furthermore, our high resolution micro-CT data reveal that the central nervous system of both <i>Doto</i> species possesses numerous accessory giant cells, suggested to be neurons herein. In addition, the phylogenetic tree of all <i>Doto</i> species sequenced to date suggests a scenario for the evolution of the reproductive system in this genus: bursa copulatrix seems to have been reduced and the acquisition of a distal connection of the oviduct to the nidamental glands is a synapomorphy of the Antarctic <i>Doto</i> species. Overall, the combination of thorough morphological and anatomical description and molecular analyses provides a comprehensive means to characterize and delineate species, thus suggesting evolutionary scenarios.</p></div

Micro-CT reconstructions of the internal organs of <i>D</i>. <i>antarctica</i> (left column) and <i>D</i>. <i>carinova</i> Moles, Avila & Wägele n. sp. (right column).

<p><b>A</b>–<b>B</b> Right antero-lateral view of all reconstructed organs. <b>C</b>–<b>D</b> Left antero-lateral view of the circulatory, digestive, excretory, and nervous systems. <b>E</b>–<b>F</b> Right lateral view of the male reproductive system. <b>G</b>–<b>H</b> Left lateral view of the reproductive system (mucus gland is not depicted here since it covers the whole view). <i>am</i> ampulla; <i>adiv</i> ampulla diverticulum; <i>au</i> auricle; <i>bc</i> bursa copulatrix; <i>cis</i> circulatory sinuses; <i>cgl</i> capsule gland; <i>cpg</i> cerebropleural ganglion; <i>dg</i> distal gonoduct; <i>dgdiv</i> digestive gland diverticula; <i>dgl</i> digestive gland (only depicted in <i>D</i>. <i>carinova</i> n. sp.); <i>gc</i> giant cells; <i>gon</i> gonad; <i>ht</i> heart; <i>int</i> intestine; <i>kid</i> kidney; <i>megl</i> membrane gland; <i>mugl</i> mucus gland; <i>oes</i> oesophagus; <i>od</i> odontophore; <i>ot</i> oral tube; <i>ov</i> oviduct; <i>peg</i> pedal ganglion; <i>pen</i> penis; <i>per</i> pericardium; <i>pg</i> proximal gonoduct; <i>pha</i> pharynx; <i>pro</i> prostate; <i>rad</i> radula; <i>rhg</i> rhinophoral ganglion; <i>rhi</i> rhinophore; <i>rhs</i> rhinophoral sheath; <i>sgl</i> salivary gland; <i>sin</i> sinus; <i>sp</i> sphincter; <i>sto</i> stomach; <i>vag</i> vagina; <i>vd</i> vas deferens; <i>ven</i> ventricle.</p

Histological slide of outer surface of the egg mass in <i>Doto carinova</i> Moles, Avila & Wägele n. sp.

<p>Histological slide of outer surface of the egg mass in <i>Doto carinova</i> Moles, Avila & Wägele n. sp.</p

Phylogenetic tree of <i>Doto</i> species based on the combined COI, 16S, and H3 genes using Bayesian inference (BI) and maximum-likelihood (ML).

<p>Numbers on nodes indicate posterior probability values (BI) and bootstrap support values (ML). Specimens sequenced are in bold; <i>Doto antarctica</i> specimens are coloured in red. Schematic drawings of the reproductive system of <i>Doto</i> species are depicted (A–D), as well as the unsequenced <i>D</i>. <i>uva</i> Marcus, 1955 (E). <i>bc</i> bursa copulatrix; <i>gd</i> gonoduct; <i>nigl</i> nidamental glands; <i>pen</i> penis; <i>rs</i> receptaculum seminis; <i>vd</i> vas deferens.</p