87 research outputs found
Description of the microbial diversity associated with Chorocaris chacei : a possible double symbiosis
No full textBien que très peu explorés, les fonds des océans pourraient représenter le futur de l’industrie minière mondiale. L’impact écologique de ces activités reste encore inconnu, notamment sur les cibles privilégiées que sont les systèmes hydrothermaux et leurs écosystèmes. Ce travail s’intéresse à la crevette Rimicaris chacei et à sa potentielle symbiose avec des bactéries hydrothermales. R. chacei présente une alimentation mixte, nécrophagie et symbiose, plasticité alimentaire qui pourrait être un atout en cas de modification de son environnement. La proximité phylogénétique et écologique de C. chacei avec une autre crevette hydrothermale, Rimicaris exoculata, laisse supposer une possible histoire commune de leurs symbioses. Deux compartiments biologiques des crevettes ont été étudiés au cours de ce travail, le céphalothorax et le tube digestif, via deux approches complémentaires: l’imagerie et la biologie moléculaire. Nous souhaitions répondre à deux questions principales (1) Décrire le type d’association entre la crevette et ses « symbiontes » d’un point de vue morpho-anatomique et phylogénétique. (2) Evaluer le degré de similarité entre les symbiontes de C. chacei, et R. exoculata via une approche de métabarcoding. Notre but est de déterminer si une possible variation de la distribution des symbiontes existe chez ces deux espèces en fonction du site hydrothermal d’origine (facteur environnemental), en fonction de l’espèce de crevette étudiée (facteur hôte), ou une association de ces deux facteurs. La bioinformatique ayant une part importante dans l’analyse des données de barcoding/metabarcoding, une partie du manuscrit lui est dédiée pour « désacraliser » ce type d’analyse.Deep-sea ocean may soon represent deep-sea mining industry future. However, these environments are still poorly explored. Therefore, mining issues on deep-sea ecosystems are not yet evaluated, mostly on their main target: the deep-sea hydrothermal vents. Our study focused on a shrimp, Rimicaris chacei and to its potential symbioses with chemoautotrophic microbial communities.This shrimp have a mixotrophic behaviour, mixed between necrophagy and symbiosis. It could therefore have a potential trophic plasticity in case of steep environmental modifications. Moreover, C. chacei is closely related to Rimicaris exoculata, in terms of both phylogeny and ecology. This could let suppose a common symbiosis history, presenting nowadays two different levels of association.Two potential symbiotic microbial communities have been studied here, one located in the cephalothorax and the other in the digestive tract, using two complementary approaches: microscopy and molecular analyses. Two main points have been focused in our work: (1) Describing the shrimp and its associated microbial communities in terms of morphology, repartition and phylogeny. (2) Using a metabarcoding approach to evaluate the similarity level shared between C. chacei and R. exoculata associated microbial communities. We intend to analyse a possible genetic variation among symbionts of the two hosts, whether it would be linked to the hydrothermal vent origin (geography), or to the studied shrimp (host), or both of them. As bioinformatics was an important part of my work to analyse barcoding/metabarcoding data, a part of my thesis is dedicated to explain these analyses as a tutorial for all future users
DONNEES SUR LES INTERACTIONS BIOGEOCHIMIQUES EN MILIEU HYDROTHERMAL (L'EXEMPLE D'ALVINELLA POMPEJANA (DOCTORAT : PHYSIOLOGIE))
No full textAIX-MARSEILLE2-BU Méd/Odontol. (130552103) / SudocPARIS-BIUM (751062103) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF
Rimicaris exoculata: biology and ecology of a shrimp from deep-sea hydrothermal vents associated with ectosymbiotic bacteria
No full textRimicaris exoculata, the ‘blind shrimp,’ is the most abundant species living on active hydrothermal edifices at deep-sea vents of the Mid-Atlantic Ridge. Its unusually enlarged branchial chamber houses a dense ectosymbiotic community of chemoautotrophic bacteria. Long debated, shrimp nutrition has been proven to be a kind of osmotrophy, whereby small organic molecules produced by the symbionts pass through the integument of the shrimp directly into the circulatory system, rather than through the digestive system. The broad phylogenetic and metabolic diversity of this epibiotic community suggests a highly flexible and adjustable microbial consortium, adapted to the chemically contrasting environments inhabited by the shrimp. To cope with the highly fluctuating oxygen and temperature conditions of its habitat, R. exoculata possesses hemocyanin with a strong oxygen affinity, and has developed both molecular and behavioral responses to heat stresses. If R. exoculata is able to detect very dim light or chemical compounds emitted by vents, the relatively small visual and olfactory areas in the brain, along with the disproportionately enlarged higher centers, argue for a significant involvement of navigational skills using learning and place memory to orient itself within its aphotic environment. This shrimp undergoes unconventional larval development, with a primary lecithotrophic stage followed by an extended planktotrophic period, allowing a huge potential for dispersion. In light of mining licenses posing a threat for deep-sea environments, this species is a model still to be studied to better understand life in extreme deep-sea ecosystems at the global scale of an ocean
Colonisation of newly-opened habitat by a pioneer species, Alvinella pompejana (Polychaeta: Alvinellidae), at East Pacific Rise vent sites
No full textAuthor Posting. © Inter-Research, 2005. This article is posted here by permission of Inter-Research for personal use, not for redistribution. The definitive version was published in Marine Ecology Progress Series 302 (2005): 147-157, doi:10.3354/meps302147.Animal communities on the walls of deep-sea hydrothermal chimneys are distributed in mosaics of patches that may evolve as local environmental conditions change and biological interactions develop. Alvinella pompejana Desbruyères et Laubier, 1980 is one of the first metazoan colonisers of new surfaces created by mineral precipitation, and therefore may be particularly important in community establishment in active parts of smokers. Here our goal was to investigate the colonisation mechanisms of A. pompejana in new patches and determine whether these mechanisms may influence population structure and reproductive patterns in this species. We deployed a series of TRAC (Titanium Ring for Alvinellid Colonisation) devices at East Pacific Rise (EPR) vent sites to compare the size and stage (i.e. reproductive maturity) distribution of A. pompejana individuals between recently colonised patches (TRACs) and established patches (grabbed by submersible). TRACs deployed for short time periods (11 d to 1 mo) were generally colonised by smaller individuals than those found in background populations or in TRACs deployed for longer time periods (>1 mo). Colonists into new patches were a mix of juveniles and individuals that were sexually mature but non-reproductive (i.e. not producing gametes), whereas background population and older patches harboured a mixture of individuals at different stages including reproductive females. Although some individuals may have recruited on TRACs as larvae, the major colonisation process involved was probably immigration of post-larval stages. In long-term TRAC, reproductive females were not reproductively synchronised. In this dynamic environment, reproduction would be triggered by the disturbance/migration processes, explaining the heterogeneity observed in reproductive patterns.The research
was funded by INSU, CNRS, IFREMER, Dorsales and NSF
grant OCE-9712233 to L.S.M
Comparison of chemoreceptive abilities of the hydrothermal shrimp mirocaris fortunata and the coastal shrimp palaemon elegans
No full textInternational audienceChemoreception might play an important role for endemic shrimp that inhabit deep and dark hydrothermal vents to find food sources and to locate active edifices that release specific chemicals. We compared the chemosensory abilities of the hydrothermal shrimp Mirocaris fortunata and the coastal related species, Palaemon elegans. The detection of diverse ecologically relevant chemical stimuli by the antennal appendages was measured with electroantennography. The 2 species can detect food-related odor and sulfide, a short-distance stimulus, via both their antennae and antennules. Neither iron nor manganese, considered as long-distance stimuli, was detected by the antennal appendages. Investigation of the ultrastructure of aesthetasc sensilla revealed no specific features of the hydrothermal species regarding innervation by olfactory sensory neurons. Pore-like structures occurring in the aesthetasc cuticle and dense bacterial covering seem to be unique to hydrothermal species, but their potential link to chemoreception remains elusive
BEEYOND - Foundation of the Company & Market Entry
No full textThis bachelor thesis depicts the author's journey over the last months, from the discovery of a business idea inspired by an innovative blockchain application over the creation of a solid concept in the form of a business plan to the development & implementation on a strategic as well as functional level. By applying his theoretical knowledge acquired in the Major "International Entrepreneurship", the author gained the necessary skillset to establish the company, develop the market entry strategy and begin with its practical implementation
Processes controlling the physico-chemical micro-environments associated with Pompeii worms
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