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CONTENT - International Society of Zoological Sciences

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S20 ICZ2008 - Abstracts<br />

Dispersal and colonization strategy <strong>of</strong> the whale bone eating<br />

worm Osedax<br />

Florence Pradillon, Masaru Kawato, Katsunori Fujikura, Chikayo<br />

Noda and Yoshihiro Fujiwara<br />

Extremobiosphere Research Center, Japan Agency for Marine-<br />

Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho,<br />

Yokosuka, Kanagawa, Japan<br />

In the deep-sea, whale falls bring massive organic enrichment in<br />

single pulses that significantly impact on local deep-sea<br />

communities. Whale falls provide island habitat for a specialized<br />

fauna adapted to live on whale remains 1 . The Siboglinid<br />

polychaetes Osedax exhibit a unique relationship to whale bones.<br />

Females grow a root organ that harbor symbiotic heterotrophic<br />

bacteria and that infiltrate bones and extract lipid and collagen for<br />

nutrition 2 . Since the discovery <strong>of</strong> this genus, 10 species have been<br />

reported, all associated to decaying bones, but in a wide range <strong>of</strong><br />

environmental condition 3-6 . The success <strong>of</strong> Osedax in colonizing<br />

such a patchy habitat over broad geographic and bathymetric<br />

ranges implies efficient dispersal and colonization strategies.<br />

We analyzed colonization patterns <strong>of</strong> Osedax species on a sperm<br />

whale carcass implanted at 925 m depth in Sagami Bay (Japan).<br />

Seven different species successively colonizing the bones were<br />

identified using molecular techniques. O. japonicus that colonizes<br />

a close but shallow (225 m) sperm whale fall site 7 was not found,<br />

whereas 2 <strong>of</strong> the early colonists in Sagami Bay are also known<br />

from distant sites in the western Pacific (<strong>of</strong>f California). This<br />

suggests very efficient dispersal possibly limited by depth related<br />

environmental parameters. We investigated embryonic and larval<br />

development in order to understand mechanisms underlying<br />

dispersal and colonization efficiency. Embryonic development<br />

exhibits remarkably rapid rates even at low temperature. This<br />

feature is usually associated with short dispersal range, suggesting<br />

that spatial and temporal frequency <strong>of</strong> suitable bones may be<br />

essential for maintaining Osedax population.<br />

Disclosing chemosynthesis in bivalve species from mud<br />

volcanoes in the gulf <strong>of</strong> Cadiz<br />

Clara F. Rodrigues, Gordon Webster, Andrew Weightman and<br />

Marina R. Cunha<br />

Campus Universitario de Santiago, 3810-093, Aveiro, Portugal<br />

Symbiotic associations with thiotrophic and methanotrophic<br />

bacteria occur in a wide array <strong>of</strong> animal species that live in<br />

reducing environments with high sulfide and methane<br />

concentrations, such as hydrothermal vents, deep-sea whale fall,<br />

sunken wood, and cold seeps. Since the discovery in 1999 <strong>of</strong> the<br />

first mud volcano in the Gulf <strong>of</strong> Cadiz, about 30 other sites at<br />

depths ranging from 200 to 3900 m, with varying degrees <strong>of</strong><br />

hydrocarbon-rich gas seepage activity have been located and<br />

sampled. Chemosynthetic bivalve species include the widespread<br />

species Acharax sp. and Solemya sp but also other species like<br />

Lucinoma sp., Thyasira vulcolutre and Bathymodiolus mauritanicus.<br />

Stable isotopes analyses 13 C, 15 N, 34 S) show the major role <strong>of</strong><br />

chemoautotrophic derived C in the food web <strong>of</strong> mud volcanoes. 13 C<br />

values measured in solemyids, lucinid and thyasirids specimens<br />

support the hypothesis <strong>of</strong> a thiotrophic nutrition. On the other hand,<br />

isotopic signatures <strong>of</strong> Bathymodiolus specimens collected were in<br />

line for methanotrophic nutrition. Molecular identification <strong>of</strong><br />

chemosynthetic prokaryotic endosymbionts associated with these<br />

species was carried out using PCR-DGGE analysis <strong>of</strong> bacterial<br />

16S rRNA genes and analysis <strong>of</strong> bacterial clone libraries.<br />

Phylogenetic analysis <strong>of</strong> 16S rRNA genes from the gill tissues<br />

indicate that the bacterial sequences found were related to sulfuroxidizing<br />

endosymbionts from other deep-sea chemosynthetic<br />

environments. The divergence observed for Bathymodiolus<br />

mauritanicus (stable isotope values extremely depleted in 13 C<br />

suggested methano-trophic nutrition but molecular studies<br />

revealed the presence <strong>of</strong> sulfur-oxidizing bacteria) may be<br />

indicative <strong>of</strong> the occurrence <strong>of</strong> dual symbiosis but only further<br />

studies can corroborate that.<br />

- 84 -<br />

Transcriptomics study <strong>of</strong> the annelid host Riftia pachyptila<br />

symbiotic with chemosynthetic bacteria<br />

Sophie Sanchez 1 , Stéphane Hourdez 2 and François H. Lallier 2<br />

1Equipe<br />

Horloge circadienne, Laboratoire Arago, BP 74, 66650<br />

Banyuls sur mer, France<br />

2,<br />

Equipe Ecophysiologie : Evolution et Adaptation Moléculaires,<br />

Station Biologique, BP 74, 29680 Rosc<strong>of</strong>f, France<br />

The giant hydrothermal vent tubeworm Riftia pachyptila (Siboglinid<br />

Polychaete Annelid) is probably one <strong>of</strong> the most extensively<br />

studied organisms that are symbiotic with sulfide-oxidizing bacteria.<br />

Located in a specialized internal organ, the trophosome (TR),<br />

these symbionts depend on the host for their supply in O2, CO2<br />

and H2S that are acquired from the environment by the branchial<br />

plume (BR) <strong>of</strong> the worm. We used a global molecular approach by<br />

Subtractive Suppression Hybridization (SSH) to try to identify<br />

proteins involved in the metabolites exchanges in these tissues.<br />

Four subtractive cDNA libraries were constituted, with the body<br />

wall (BW) as a reference tissue (BR-BW, BW-BR, TR-BW, BW-<br />

TR). More than 700 sequences were obtained with an average <strong>of</strong><br />

45 different cDNAs per library, <strong>of</strong> which half could be identified.<br />

The differential expression <strong>of</strong> the most interesting transcripts was<br />

confirmed by quantitative PCR. A new carbonic anhydrase<br />

transcript (RpCAbr) specifically expressed in the gills was obtained<br />

in addition to the one already known (RpCAtr) that is mostly<br />

expressed in the trophosome (checking by fluorescent in situ<br />

hybridization). A myohemerythrin transcript, obtained in the TR-<br />

BW library, appears clearly specific <strong>of</strong> the trophosome tissue.<br />

Given that it is a particularly rare pigment in Annelids, this<br />

transcript was overexpressed in a heterologous system to explore<br />

a more functional aspect. In the branchial plume tissue, the Major<br />

Vault Protein could constitute an interesting clue for further studies<br />

about the transport <strong>of</strong> metabolites.<br />

Changes in lipid quality and fatty acids pr<strong>of</strong>ile <strong>of</strong> sardine oil<br />

(Sardina pilchardus) during storage: The effects <strong>of</strong><br />

temperature and α-tocopherol<br />

Salah Selmi 1 , Nawzet Bouriga 2 , S. Sadok 1 , Irineu Batista 3 , Narcisa<br />

Bandarra 3 and Maria Leonor Nunes 3<br />

1<br />

Institut National des <strong>Sciences</strong> et Technologies de la Mer, Port La<br />

Goulette 2060, Tunisia<br />

2<br />

Unité de Biologie marine, Faculté des <strong>Sciences</strong> de Tunis, 2092<br />

Campus universitaire, Tunisia<br />

3<br />

Department <strong>of</strong> Technological Innovation and Upgrading <strong>of</strong><br />

Fishery Products, INRB/IPIMAR, Av. de Brasília, 1449-006 Lisboa,<br />

Portugal<br />

Sardine oil obtained through industrial mince preparation was<br />

stored at two different temperatures (+4C° and +35°C) during 28<br />

days with or without the addition <strong>of</strong> α-tocopherol. The peroxide<br />

values and fatty acid composition were determined to monitor<br />

oxidative lipid changes during storage. Peroxide values increased<br />

significantly (p < 0.05) during storage to reach 4.36 mEq O2/kg oil<br />

and 24.9 mEq O2/kg oil at +4°C and +35°C, respectively. Oil<br />

treated with α-tocopherol showed lower hydroperoxyde levels than<br />

did the control lot (3.3 mEq O2/kg oil and 21.47 mEq O2/kg oil at<br />

+4°C and +35°C, respectively).<br />

At +4°C, saturated and monounsaturated fatty acids remained<br />

constant after storage. Polyunsaturated fatty acids (34.05%)<br />

decreased significantly at the end <strong>of</strong> storage (31.3%). At +35°C, a<br />

50% decrease <strong>of</strong> polyunsaturated fatty acids was observed after<br />

28 days <strong>of</strong> storage, reaching 18.2%. Saturated and<br />

monounsaturated fatty acids instead showed a significant increase.<br />

It is concluded that α-tocopherol has a positive affect on the<br />

oxidation <strong>of</strong> sardine oil stored at +35°C.

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