scholarly journals Identifying conserved molecular mechanisms of thermo-acclimation in symbiotic organisms

2018 ◽  
Author(s):  
Homere J. Alves Monteiro ◽  
Chloe Brahmi ◽  
Anderson Blair Mayfield ◽  
Jeremie Vidal-Dupiol ◽  
Bruno Lapeyre ◽  
...  
Keyword(s):  
High Temperatures ◽  
Molecular Mechanisms ◽  
Seawater Temperature ◽  
French Polynesia ◽  
Giant Clam ◽  
Pocillopora Damicornis ◽  
Free Living ◽  
Module Preservation ◽  
Tridacna Maxima ◽  
Symbiotic Organisms

Seawater temperature rise in French Polynesia has repeatedly resulted in symbiosis breakdown between giant clam (Tridacna maxima) and dinoflagellates (Symbiodinium spp.), particularly in small individuals. Herein, we explored the physiological and gene expression responses of the clam hosts and their photosynthetically active symbionts over a 65-day experiment in which clams were exposed to either normal or environmentally relevant elevated seawater temperatures. These data were combined with publicly available data for both free-living Symbiodinium (clades C1 and F) and Symbiodinium spp. in hospite with the coral Pocillopora damicornis. Gene module preservation analysis revealed that the function of the symbionts' photosystem II was impaired at high temperatures, and this response was conserved across all holobionts and Symbiodinium clades examined. Similarly, activation of the phytohormone abscisic acid signaling and epigenetics modulation appeared to be a key response mechanisms for symbionts in hospite with giant clams exposed to high temperatures and also distinguish thermo-tolerant from thermo-sensitive Symbiodinium C1 phenotypes.

scholarly journals Growth, Survival and Reproduction of the Giant Clam Tridacna maxima (Röding 1798, Bivalvia) in Two Contrasting Lagoons in French Polynesia

PLoS ONE ◽  
2017 ◽  
Vol 12 (1) ◽  
pp. e0170565 ◽  
Author(s):  
Simon Van Wynsberge ◽  
Serge Andréfouët ◽  
Nabila Gaertner-Mazouni ◽  
Colette C. C. Wabnitz ◽  
Mathilde Menoud ◽  
...  
Keyword(s):  
French Polynesia ◽  
Giant Clam ◽  
Survival And Reproduction ◽  
Tridacna Maxima

scholarly journals Understanding consequences of adaptive monitoring protocols on data consistency: application to the monitoring of giant clam densities impacted by massive mortalities in Tuamotu atolls, French Polynesia

2019 ◽  
Vol 76 (4) ◽  
pp. 1062-1071
Author(s):  
Stéphane Georget ◽  
Simon Van Wynsberge ◽  
Serge Andréfouët
Keyword(s):  
Size Structure ◽  
French Polynesia ◽  
Data Consistency ◽  
Giant Clam ◽  
Q Method ◽  
Adaptive Monitoring ◽  
Tuamotu Archipelago ◽  
Tridacna Maxima ◽  
Belt Transect ◽  
Monitoring Protocols

Abstract During long-term monitoring, protocols suitable in the initial context may have to change afterward because of unforeseen events. The outcome for management can be important if the consequences of changing protocols are not understood. In Tuamotu Archipelago atolls, French Polynesia, the density of giant clams (Tridacna maxima) has been monitored for 12 years, but massive mortalities and collapsing densities forced to shift from a line-intercept transects and quadrats (LIT-Q) method to a belt-transect (BT) method. We investigated with a simulation approach the conditions (density, size structure, aggregation of giant clam populations) under which the two methods provided different results. A statistical model relating the BT density to the LIT-Q density was validated using new field data acquired on the same sites with both protocols, on two atolls. The BT method usually provided higher estimates of density than the LIT-Q method, but the opposite was found for very high densities. The shape of the relationship between measurements depended on population size structure and on aggregation. Revisiting with the model the historical LIT-Q densities suggested that densities have been underestimated in the past but previously detected trends in population trajectories remained valid. The implication of these findings for management are discussed.

scholarly journals The giant clam Tridacna maxima communities of three French Polynesia islands: comparison of their population sizes and structures at early stages of their exploitation

2006 ◽  
Vol 63 (9) ◽  
pp. 1573-1589 ◽  
Author(s):  
Antoine Gilbert ◽  
Serge Andréfouët ◽  
Laurent Yan ◽  
Georges Remoissenet
Keyword(s):  
Population Size ◽  
French Polynesia ◽  
Small Scale ◽  
Giant Clam ◽  
In Situ Data ◽  
Tuamotu Archipelago ◽  
Population Sizes ◽  
Management Schemes ◽  
Tridacna Maxima ◽  
Volcanic Islands

AbstractSeveral lagoons of the atolls of Tuamotu Archipelago and volcanic islands of the Australes Archipelago (French Polynesia) are characterized by enormous populations of the clam Tridacna maxima, a species considered as endangered in many locations worldwide. Even if this resource can still be considered as virtually intact, the growing harvesting pressure to feed Tahiti's market (up to 50 t of wet matter y−1), combined with the relatively small size of these lagoons, will soon call for management action to sustain a fishery that currently targets a large, virtually pristine stock. Hence, we present T. maxima population sizes and structures for two atolls (Fangatau and Tatakoto) and one island (Tubuai), where high clam densities and population sizes have promoted a small-scale, but growing, commercial fishery since the late 1990s. We followed an earlier pilot study, in which a combination of remote sensing and in situ data provided an estimate of the Fangatau clam population size (23.6 ± 5.3 million clams, mean ± 95% confidence interval, for 4.05 km2 of mapped lagoon). We obtain 88.3 ± 10.5 and 47.5 ± 5.2 million clams for Tatakoto (mapped area of 11.46 km2) and Tubuai (mapped area of 16.3 km2), respectively. Accounting for contrasted length frequency distribution curves and one common size–weight relationship, the total biomasses are 1485 ± 177 t, 1162 ± 272 t, and 2173 ± 232 t of commercial flesh for Tatakoto, Fangatau, and Tubuai, respectively. In addition, given the legal restriction on collecting clams smaller than 12 cm, the legally harvestable biomasses are 958 ± 114 t, 1038 ± 247 t, and 1971 ± 210 t of flesh for Tatakoto, Fangatau, and Tubuai, respectively. The ratio between legal and total stock is much smaller for Tatakoto because this atoll is dominated by small clams, unlike the other two sites. The differences in population size and structure are discussed in terms of natural environment (habitats, degree of aperture to the ocean, temperature variations), providing insights on the natural variability between two similar systems (Tatakoto and Fangatau), and between different systems (the two atolls and the volcanic island of Tubuai), suggesting that future management schemes will have to be optimized locally.

scholarly journals Tissue-Specific Microbiomes of the Red Sea Giant Clam Tridacna maxima Highlight Differential Abundance of Endozoicomonadaceae

2019 ◽  
Vol 10 ◽  
Author(s):  
Susann Rossbach ◽  
Anny Cardenas ◽  
Gabriela Perna ◽  
Carlos M. Duarte ◽  
Christian R. Voolstra
Keyword(s):  
Red Sea ◽  
Giant Clam ◽  
Differential Abundance ◽  
Tissue Specific ◽  
Tridacna Maxima

First observation of the giant clam Tridacna squamosa in French Polynesia: a species range extension

Coral Reefs ◽  
2007 ◽  
Vol 26 (2) ◽  
pp. 229-229 ◽  
Author(s):  
A. Gilbert ◽  
S. Planes ◽  
S. Andréfouët ◽  
K. Friedman ◽  
G. Remoissenet
Keyword(s):  
French Polynesia ◽  
Species Range ◽  
Range Extension ◽  
Giant Clam ◽  
Tridacna Squamosa

scholarly journals Phosphoproteomic analysis of lettuce (Lactuca sativa L.) reveals starch and sucrose metabolism functions during bolting induced by high temperature

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0244198
Author(s):  
Xiaoxiao Qin ◽  
Panpan Li ◽  
Shaowei Lu ◽  
Yanchuan Sun ◽  
Lifeng Meng ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Lactuca Sativa ◽  
Molecular Mechanisms ◽  
Soluble Sugar ◽  
High Temperature Stress ◽  
Temperature Treatment ◽  
Sucrose Metabolism ◽  
High Temperature Treatment ◽  
Lactuca Sativa L

High temperatures induce early bolting in lettuce (Lactuca sativa L.), which decreases both quality and production. However, knowledge of the molecular mechanism underlying high temperature promotes premature bolting is lacking. In this study, we compared lettuce during the bolting period induced by high temperatures (33/25 °C, day/night) to which raised under controlled temperatures (20/13 °C, day/night) using iTRAQ-based phosphoproteomic analysis. A total of 3,814 phosphorylation sites located on 1,766 phosphopeptides from 987 phosphoproteins were identified after high-temperature treatment,among which 217 phosphoproteins significantly changed their expression abundance (116 upregulated and 101 downregulated). Most phosphoproteins for which the abundance was altered were associated with the metabolic process, with the main molecular functions were catalytic activity and transporter activity. Regarding the functional pathway, starch and sucrose metabolism was the mainly enriched signaling pathways. Hence, high temperature influenced phosphoprotein activity, especially that associated with starch and sucrose metabolism. We suspected that the lettuce shorten its growth cycle and reduce vegetative growth owing to changes in the contents of starch and soluble sugar after high temperature stress, which then led to early bolting/flowering. These findings improve our understanding of the regulatory molecular mechanisms involved in lettuce bolting.

scholarly journals Chemosensory mechanisms of host seeking and infectivity in skin-penetrating nematodes

2020 ◽  
Vol 117 (30) ◽  
pp. 17913-17923 ◽  
Author(s):  
Spencer S. Gang ◽  
Michelle L. Castelletto ◽  
Emily Yang ◽  
Felicitas Ruiz ◽  
Taylor M. Brown ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Strongyloides Stercoralis ◽  
Sensory Cues ◽  
Ancylostoma Ceylanicum ◽  
Free Living ◽  
Infective Larvae ◽  
Host Seeking ◽  
Third Stage ◽  
Olfactory Preferences ◽  
Insight Into

Approximately 800 million people worldwide are infected with one or more species of skin-penetrating nematodes. These parasites persist in the environment as developmentally arrested third-stage infective larvae (iL3s) that navigate toward host-emitted cues, contact host skin, and penetrate the skin. iL3s then reinitiate development inside the host in response to sensory cues, a process called activation. Here, we investigate how chemosensation drives host seeking and activation in skin-penetrating nematodes. We show that the olfactory preferences of iL3s are categorically different from those of free-living adults, which may restrict host seeking to iL3s. The human-parasitic threadwormStrongyloides stercoralisand hookwormAncylostoma ceylanicumhave highly dissimilar olfactory preferences, suggesting that these two species may use distinct strategies to target humans. CRISPR/Cas9-mediated mutagenesis of theS. stercoralis tax-4gene abolishes iL3 attraction to a host-emitted odorant and prevents activation. Our results suggest an important role for chemosensation in iL3 host seeking and infectivity and provide insight into the molecular mechanisms that underlie these processes.

scholarly journals Symbiont population control by host-symbiont metabolic interaction in Symbiodiniaceae-cnidarian associations

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Tingting Xiang ◽  
Erik Lehnert ◽  
Robert E. Jinkerson ◽  
Sophie Clowez ◽  
Rick G. Kim ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Population Control ◽  
Algal Growth ◽  
Glutamate Synthase ◽  
Free Living ◽  
Nitrogen Acquisition ◽  
Symbiotic Algae ◽  
Nitrogen Ratio ◽  
Algal Endosymbiont ◽  
Exaiptasia Pallida

AbstractIn cnidarian-Symbiodiniaceae symbioses, algal endosymbiont population control within the host is needed to sustain a symbiotic relationship. However, the molecular mechanisms that underlie such population control are unclear. Here we show that a cnidarian host uses nitrogen limitation as a primary mechanism to control endosymbiont populations. Nitrogen acquisition and assimilation transcripts become elevated in symbiotic Breviolum minutum algae as they reach high-densities within the sea anemone host Exaiptasia pallida. These same transcripts increase in free-living algae deprived of nitrogen. Symbiotic algae also have an elevated carbon-to-nitrogen ratio and shift metabolism towards scavenging nitrogen from purines relative to free-living algae. Exaiptasia glutamine synthetase and glutamate synthase transcripts concomitantly increase with the algal endosymbiont population, suggesting an increased ability of the host to assimilate ammonium. These results suggest algal growth and replication in hospite is controlled by access to nitrogen, which becomes limiting for the algae as their population within the host increases.

scholarly journals Metabarcoding reveals distinct microbiotypes in the giant clam Tridacna maxima

Microbiome ◽  
2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Isis Guibert ◽  
Gael Lecellier ◽  
Gergely Torda ◽  
Xavier Pochon ◽  
Véronique Berteaux-Lecellier
Keyword(s):  
Giant Clam ◽  
Tridacna Maxima
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