CONTENT - International Society of Zoological Sciences

S20 ICZ2008 - Abstracts
Dispersal and colonization strategy of the whale bone eating
worm Osedax
Florence Pradillon, Masaru Kawato, Katsunori Fujikura, Chikayo
Noda and Yoshihiro Fujiwara
Extremobiosphere Research Center, Japan Agency for Marine-
Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho,
Yokosuka, Kanagawa, Japan
In the deep-sea, whale falls bring massive organic enrichment in
single pulses that significantly impact on local deep-sea
communities. Whale falls provide island habitat for a specialized
fauna adapted to live on whale remains 1 . The Siboglinid
polychaetes Osedax exhibit a unique relationship to whale bones.
Females grow a root organ that harbor symbiotic heterotrophic
bacteria and that infiltrate bones and extract lipid and collagen for
nutrition 2 . Since the discovery of this genus, 10 species have been
reported, all associated to decaying bones, but in a wide range of
environmental condition 3-6 . The success of Osedax in colonizing
such a patchy habitat over broad geographic and bathymetric
ranges implies efficient dispersal and colonization strategies.
We analyzed colonization patterns of Osedax species on a sperm
whale carcass implanted at 925 m depth in Sagami Bay (Japan).
Seven different species successively colonizing the bones were
identified using molecular techniques. O. japonicus that colonizes
a close but shallow (225 m) sperm whale fall site 7 was not found,
whereas 2 of the early colonists in Sagami Bay are also known
from distant sites in the western Pacific (off California). This
suggests very efficient dispersal possibly limited by depth related
environmental parameters. We investigated embryonic and larval
development in order to understand mechanisms underlying
dispersal and colonization efficiency. Embryonic development
exhibits remarkably rapid rates even at low temperature. This
feature is usually associated with short dispersal range, suggesting
that spatial and temporal frequency of suitable bones may be
essential for maintaining Osedax population.
Disclosing chemosynthesis in bivalve species from mud
volcanoes in the gulf of Cadiz
Clara F. Rodrigues, Gordon Webster, Andrew Weightman and
Marina R. Cunha
Campus Universitario de Santiago, 3810-093, Aveiro, Portugal
Symbiotic associations with thiotrophic and methanotrophic
bacteria occur in a wide array of animal species that live in
reducing environments with high sulfide and methane
concentrations, such as hydrothermal vents, deep-sea whale fall,
sunken wood, and cold seeps. Since the discovery in 1999 of the
first mud volcano in the Gulf of Cadiz, about 30 other sites at
depths ranging from 200 to 3900 m, with varying degrees of
hydrocarbon-rich gas seepage activity have been located and
sampled. Chemosynthetic bivalve species include the widespread
species Acharax sp. and Solemya sp but also other species like
Lucinoma sp., Thyasira vulcolutre and Bathymodiolus mauritanicus.
Stable isotopes analyses 13 C, 15 N, 34 S) show the major role of
chemoautotrophic derived C in the food web of mud volcanoes. 13 C
values measured in solemyids, lucinid and thyasirids specimens
support the hypothesis of a thiotrophic nutrition. On the other hand,
isotopic signatures of Bathymodiolus specimens collected were in
line for methanotrophic nutrition. Molecular identification of
chemosynthetic prokaryotic endosymbionts associated with these
species was carried out using PCR-DGGE analysis of bacterial
16S rRNA genes and analysis of bacterial clone libraries.
Phylogenetic analysis of 16S rRNA genes from the gill tissues
indicate that the bacterial sequences found were related to sulfuroxidizing
endosymbionts from other deep-sea chemosynthetic
environments. The divergence observed for Bathymodiolus
mauritanicus (stable isotope values extremely depleted in 13 C
suggested methano-trophic nutrition but molecular studies
revealed the presence of sulfur-oxidizing bacteria) may be
indicative of the occurrence of dual symbiosis but only further
studies can corroborate that.
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Transcriptomics study of the annelid host Riftia pachyptila
symbiotic with chemosynthetic bacteria
Sophie Sanchez 1 , Stéphane Hourdez 2 and François H. Lallier 2
1Equipe
Horloge circadienne, Laboratoire Arago, BP 74, 66650
Banyuls sur mer, France
2,
Equipe Ecophysiologie : Evolution et Adaptation Moléculaires,
Station Biologique, BP 74, 29680 Roscoff, France
The giant hydrothermal vent tubeworm Riftia pachyptila (Siboglinid
Polychaete Annelid) is probably one of the most extensively
studied organisms that are symbiotic with sulfide-oxidizing bacteria.
Located in a specialized internal organ, the trophosome (TR),
these symbionts depend on the host for their supply in O2, CO2
and H2S that are acquired from the environment by the branchial
plume (BR) of the worm. We used a global molecular approach by
Subtractive Suppression Hybridization (SSH) to try to identify
proteins involved in the metabolites exchanges in these tissues.
Four subtractive cDNA libraries were constituted, with the body
wall (BW) as a reference tissue (BR-BW, BW-BR, TR-BW, BW-
TR). More than 700 sequences were obtained with an average of
45 different cDNAs per library, of which half could be identified.
The differential expression of the most interesting transcripts was
confirmed by quantitative PCR. A new carbonic anhydrase
transcript (RpCAbr) specifically expressed in the gills was obtained
in addition to the one already known (RpCAtr) that is mostly
expressed in the trophosome (checking by fluorescent in situ
hybridization). A myohemerythrin transcript, obtained in the TR-
BW library, appears clearly specific of the trophosome tissue.
Given that it is a particularly rare pigment in Annelids, this
transcript was overexpressed in a heterologous system to explore
a more functional aspect. In the branchial plume tissue, the Major
Vault Protein could constitute an interesting clue for further studies
about the transport of metabolites.
Changes in lipid quality and fatty acids profile of sardine oil
(Sardina pilchardus) during storage: The effects of
temperature and α-tocopherol
Salah Selmi 1 , Nawzet Bouriga 2 , S. Sadok 1 , Irineu Batista 3 , Narcisa
Bandarra 3 and Maria Leonor Nunes 3
1
Institut National des Sciences et Technologies de la Mer, Port La
Goulette 2060, Tunisia
2
Unité de Biologie marine, Faculté des Sciences de Tunis, 2092
Campus universitaire, Tunisia
3
Department of Technological Innovation and Upgrading of
Fishery Products, INRB/IPIMAR, Av. de Brasília, 1449-006 Lisboa,
Portugal
Sardine oil obtained through industrial mince preparation was
stored at two different temperatures (+4C° and +35°C) during 28
days with or without the addition of α-tocopherol. The peroxide
values and fatty acid composition were determined to monitor
oxidative lipid changes during storage. Peroxide values increased
significantly (p < 0.05) during storage to reach 4.36 mEq O2/kg oil
and 24.9 mEq O2/kg oil at +4°C and +35°C, respectively. Oil
treated with α-tocopherol showed lower hydroperoxyde levels than
did the control lot (3.3 mEq O2/kg oil and 21.47 mEq O2/kg oil at
+4°C and +35°C, respectively).
At +4°C, saturated and monounsaturated fatty acids remained
constant after storage. Polyunsaturated fatty acids (34.05%)
decreased significantly at the end of storage (31.3%). At +35°C, a
50% decrease of polyunsaturated fatty acids was observed after
28 days of storage, reaching 18.2%. Saturated and
monounsaturated fatty acids instead showed a significant increase.
It is concluded that α-tocopherol has a positive affect on the
oxidation of sardine oil stored at +35°C.