Lemoine 1 , M-A Berimey 1 , I Arzul 2 , C Calarnou 1 ,

1  _{Université  des  Antilles  et  de  la  Guyane,  UMR  BOREA  DYNECAR  EA926,  Campus  de  Fouillole,  UFR  SEN}   Laboratoire  de  biologie  marine,  BP592,  97117  Pointe  à  Pitre,  France.  

2  _{IFREMER    Laboratoire  de  génétique  et  pathologies  des  mollusques,  Station  de  La  Tremblade  -­‐  Ronce}   Les  Bains  -­‐  17390  La  Tremblade  

slemoine@univ-ag.fr  

Protozoan parasites of the genus Perkinsus infect marine mollusks throughout the world. The genus includes seven species P. marinus, P. olseni (=atlanticus), P. qugwadi, P. chesapeaki (= andrewsi), P. mediterraneus, P. honshuensis and P. Beihaiensis. Two species (P. olseni and P. marinus) receive more attention because they can dramatically affect the physiology of their hosts causing significant mortality in affected bivalve population (Choi and Park 2010; Villalba et al. 2004).The mangrove oyster, Crassostrea rhizophorae is an important resource of Brazil and Mexique and few studies concern parasitism on this species (Littlewood 2000; Sabry et al., 2007, 2009). No studies have been conducted in Caribbean areas and especially in the French West Indies where C. rhizophorae is not a commercial aquaculture species. In fact no aquaculture mollusk exists in the region and consequently no commercially exploited bivalve mollusks have been imported in Guadeloupe.

We examined adult oysters (40-80mm) for the presence of Perkinsus throught FTM assay and molecular diagnosis (PCR). A total of 70 adult specimens were collected in January- February 2011 at four stations. A macroscopic examination of the tissues was carried out in order to evaluate the presence or signs of parasitism.

In the present study we describe for the first time a parasite of the genus Perkinsus infecting the wild mangrove oyster Crassostrea rhizophorae from the Guadeloupe coast. Oyster gill, digestive gland and mantle tissues incubated in Ray’s Fluid Thioglycollate Medium (RFTM) revealed the presence of spherical hypnospores. Prevalence of this parasite was strong in the four stations studied (50 to 100%). The prevalence (50% to 100%) in Guadeloupe was very strong compared with 17 % in Crassostrea ariakensis of china (Moss et al., 2008a) and 7 % in C. rhizophorae of Brazil (Sabry et al., 2009).PCR assays specific to the genus Perkinsus for the internal transcribed spacer (ITS) region of the ribosomal ribonucleic acid (rRNA) gene complex followed by sequencing confirmed a strong homology (99%) with P. beihaiensis infecting Chinese oysters.

90. Ligand Binding at Heme a3 of Cytochrome c Oxidase Induces Conformational

Changes in Transmembrane Segments of Subunit-II of the Enzyme.

T A Alleyne and D N Ignacio

Faculty  of  Medical  Sciences,  The  University  of  the  West  Indies,  St  Augustine  Campus   Trinidad  and  Tobago  

Cytochrome c oxidase (COX), complex IV of the electron transport chain, catalyzes the transfer of electrons from its substrate cytochrome c to molecular oxygen which becomes reduced to water. This critical step of oxidative phosphorylation occurs at two vastly different rates that are thought to be linked to different enzyme conformations. We have postulated that the reduction of oxygen at heme a3 of COX reduces the distance and enhances the interaction between the long hydrophobic side chain of this heme and the transmembrane segments of COX subunit-II. Here we used computer modelling to investigate the correctness of this postulation.

We downloaded from the Protein Data Bank, the structures of fully oxidized and CO bound COX, both resolved at 2.8Å. We also obtained the structures of oxidized CN-COX and reduced CN-COX resolved at 2.00 and 2.05 Å respectively. Using the Swiss PDB Viewer each COX structure was manipulated to display only its heme a3 and the two transmembrane portions of subunit-II. Next the distances separating the end of the heme side chain from the residues in the transmembrane segments of COX subunit-II were recorded and compared for the different COX structures. Also the distances from one tip of the heme to the next were recorded for the different forms of COX.

The analysis found that compared to what pertained for the fully oxidized COX, the distances between the end of the heme side chain and the residues of COX subunit-II were smaller for the CO bound COX. The most significant movement involved Ile-34 for which the distance fell by as much as 1.14 Å; the biggest decrease of 1.31 Å, though involved the remote Leu-33. The conformational changes for the reduced CN bound COX were much smaller. We conclude that the reduction of ligands at heme a3 triggers a conformational change that moves the heme side chain closer to the transmembrane sections of COX subunit-II; the two structures then experience enhanced hydrophobic interaction contributing to enhanced rates of ligand reduction.

91. Conservation of the Pterocarpus offinalis swamp forest in the Lesser Antilles:

Experimental reforestation of herbaceous swamps and wet meadows

Maguy Dulormne1* Daniel Imbert1 and Vanessa Virapin1

1  _{UMR  ECOFOG  -­‐  DYNECAR,  Université  des  Antilles  et  de  la  Guyane,  UFR  des  Sciences  Exactes  et}   Naturelles,  BP.  592,  97159  Pointe-­‐à-­‐Pitre,  Guadeloupe  (F.W.I.).  

mdulormn@univ-­‐ag.fr  

The Pterocarpus officinalis swamp forest is an endangered Caribbean ecosystem. The main anthropogenic threats to this ecosystem result from land reclamation, for agricultural purposes during colonial times and for urban construction during the last century. As a result, the landward edges of remaining patches of the Pterocarpus officinalis swamp forest are mostly fringed by various monodominant herbaceous swamps or by periodically flooded meadows. Current models of climate change predict an increasing rise of the sea level and, especially for the central part of the Caribbean, lower annual rainfall amounts. Such conditions are expected to increase salinity level across coastal wetlands and force freshwater communities such as the Pterocarpus officinalis swamp forest to move landward, or decline.

Therefore, adaptation strategies to sea level rise along coastal areas include swamp forest restoration and promotion on the landward edges of current wetland areas. In this perspective, field experiments have been conducted in order to assess ecological requirements of P. officinalis saplings prior to large- scale reforestation projects. The rate of survival, growth, and physiologic responses of P. officinalis saplings have been evaluated in five micro-habitats each of one being characterized by a monodominant facies of vegetation: Eleocharis mutata (Cyperaceae) swamp (Em), Echinochloa guadeloupensis (Poaceae) swamp (Eg), Acrostichum danaefolium (Polypodiaceae) swamp (Ad), Paspalum vaginatum (Poaceae) meadow (Pv), and Pterocarpus officinalis (Fabaceae) forest (Po).

Flooding conditions and soil salinity (low: <6g/l) had no significant effect on the growth the P. officinalis saplings. Light availability (% of incident sunlight) varied among the five facies according to canopy height and thickness: Pv 100%; Em 90%; Eg 18%; Po 5%; Ad 2%. Shade was the main factor affecting growth among the five treatments. The rate of survival was near of 100% except in Eg and Po. Growth was higher in Pv regarding stem length, stem ramification and leaf number. Leaf traits have shown an acclimation to shade characterized by an increase of the specific leaf area, stomatal density, chlorophyll content, relative water content and osmotic leaf potential. Therefore, while adapted to grow under shady and swampy conditions, P. officinalis saplings exhibited higher growth rate in full sunlight and on drier soils (Pv). This can be explained by a high photosynthesis rate in spite of higher air evaporative demand.

This study permitted to highlight the growth performances of P. officinalis saplings in various non- forested, freshwater wetland conditions. Our results are expected to improve the success of restoration plans for the conservation of the P. officinalis swamp forest in the Caribbean.

Keywords: climate change, forest management, plant ecophysiology, swamp forest, tree growth