A Shift from Cellular to Humoral Responses Contributes to Innate Immune Memory in the Vector Snail Biomphalaria glabrata

International audienceDiscoveries made over the past ten years have provided evidence that invertebrate anti-parasitic responses may be primed in a sustainable manner, leading to the failure of a secondary encounter with the same pathogen. This phenomenon called " immune priming " or "innate immune memory" was mainly phenomenological. The demonstration of this process remains to be obtained and the underlying mechanisms remain to be discovered and exhaustively tested with rigorous functional and molecular methods, to eliminate all alternative explanations. In order to achieve this ambitious aim, the present study focuses on the Lophotrochozoan snail, Biomphalaria glabrata, in which innate immune memory was recently reported. We provide herein the first evidence that a shift from a cellular immune response (encapsulation) to a humoral immune response (biomphalysin) occurs during the development of innate memory. The molecular characterisation of this process in Biompha-laria/Schistosoma system was undertaken to reconcile mechanisms with phenomena

MIxS-SA: a MIxS extension defining the minimum information standard for sequence data from symbiont-associated micro-organisms

Funder: Marsden Fund (Royal Society of New Zealand).Funder: US NIH (grant reference number: RO1CA164719)Funder: FEDER (Grant reference number: InFoBioS n°EX011185)Funder: US NIH (Grant reference number: R01AI144016-01)Funder: EU horizon 2020 (Grant reference number: 773830)Abstract: The symbiont-associated (SA) environmental package is a new extension to the minimum information about any (x) sequence (MIxS) standards, established by the Parasite Microbiome Project (PMP) consortium, in collaboration with the Genomics Standard Consortium. The SA was built upon the host-associated MIxS standard, but reflects the nestedness of symbiont-associated microbiota within and across host-symbiont-microbe interactions. This package is designed to facilitate the collection and reporting of a broad range of metadata information that apply to symbionts such as life history traits, association with one or multiple host organisms, or the nature of host-symbiont interactions along the mutualism-parasitism continuum. To better reflect the inherent nestedness of all biological systems, we present a novel feature that allows users to co-localize samples, to nest a package within another package, and to identify replicates. Adoption of the MIxS-SA and of the new terms will facilitate reports of complex sampling design from a myriad of environments

Gametogenesis in the Pacific Oyster Crassostrea gigas: A Microarrays-Based Analysis Identifies Sex and Stage Specific Genes

Background: The Pacific oyster Crassostrea gigas (Mollusca, Lophotrochozoa) is an alternative and irregular protandrous hermaphrodite: most individuals mature first as males and then change sex several times. Little is known about genetic and phenotypic basis of sex differentiation in oysters, and little more about the molecular pathways regulating reproduction. We have recently developed and validated a microarray containing 31,918 oligomers (Dheilly et al., 2011) representing the oyster transcriptome. The application of this microarray to the study of mollusk gametogenesis should provide a better understanding of the key factors involved in sex differentiation and the regulation of oyster reproduction. Methodology/Principal Findings: Gene expression was studied in gonads of oysters cultured over a yearly reproductive cycle. Principal component analysis and hierarchical clustering showed a significant divergence in gene expression patterns of males and females coinciding with the start of gonial mitosis. ANOVA analysis of the data revealed 2,482 genes differentially expressed during the course of males and/or females gametogenesis. The expression of 434 genes could be localized in either germ cells or somatic cells of the gonad by comparing the transcriptome of female gonads to the transcriptome of stripped oocytes and somatic tissues. Analysis of the annotated genes revealed conserved molecular mechanisms between mollusks and mammals: genes involved in chromatin condensation, DNA replication and repair, mitosis and meiosis regulation, transcription, translation and apoptosis were expressed in both male and female gonads. Most interestingly, early expressed male-specific genes included bindin and a dpy-30 homolog and female-specific genes included foxL2, nanos homolog 3, a pancreatic lipase related protein, cd63 and vitellogenin. Further functional analyses are now required in order to investigate their role in sex differentiation in oysters. Conclusions/Significance: This study allowed us to identify potential markers of early sex differentiation in the oyster C. gigas, an alternative hermaphrodite mollusk. We also provided new highly valuable information on genes specifically expressed by mature spermatozoids and mature oocytes

Highly Variable Immune-Response Proteins (185/333) from the Sea Urchin, Strongylocentrotus purpuratus: Proteomic Analysis Identifies Diversity within and between Individuals

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Principal component analysis.

<p>3D Score plot using the first 3PCs identified by principal components analysis of all 31,918 transcripts in the 32 individual oyster gonads sampled from Site 1.</p

Heat map of sex specific genes.

<p>Hierarchical clustering obtained using Pearson’s correlation on the 77 genes differentially expressed in males and females (T test, p<0.01, adjusted Bonferroni’s correction, rows) and on all individual gonad samples (columns). Three sample branches are observed, mainly clustering stage 0 individuals, males, or females. Two gene branches are observed, clustering genes more expressed in males (cluster 1∶9 genes) or in females (cluster 2∶68 genes). Color represents the transformed normalized Cy3 log value obtained for each sample. The variations in transcript abundance are depicted with a color scale, in which shades of red represent higher gene expression and shades of green represent lower gene expression. St3: stage 3; St2: stage 2; St1: stage 1; St0: stage 0.</p

Expression profile of selected genes.

<p>Expression of 14 genes was measured in individual gonad samples from Site 1 (Locmariaquer, Brittany, France) and Site 2 (Baie des Veys, Normandy, France). Are displayed, expression profiles obtained by real time qPCR (histograms, left axe) and microarray (crosses, right axe). Vertical bars represent standard deviation for microarray data (doted line) and real time qPCR (plain line). mRNA expression levels of the 14 genes estimated by real-time qPCR are relative to <i>gapdh</i> (expressed in AU). Microarray data are expressed in log center reduced normalized values. Are displayed, expression profiles obtained for a gene more expressed in stage 0 and stage 1 : <i>unc-93 like protein</i> [Genbank 686276], three genes that increase in expression over the course of both male and female gametogenesis: <i>protein regulator of cytokinesis 1</i> (<i>prc1</i>) [Genbank AM861527], <i>bloom syndrome protein homolog</i> (<i>mus309</i>) [Genbank AM859057], <i>G2/Mitotic-specific cyclin-B</i> (<i>cyclin B</i>) [Genbank CU683817], <i>centromere protein F</i> (<i>cenpf</i>) [GenbankAM862170], four genes that increase in expression over the course of spermatogenesis: two unknown proteins [Genbanks AM864807 and AM857898], hypothetical protein <i>BRAFLDRAFT_118409</i> (<i>bindin</i>) [Genbank EF219429] and <i>histone H4</i> [Genbank DW713865], and five genes that increase in expression over the course of oogenesis : <i>vitellogenin-2</i> (<i>vit-2</i>) [Genbank CX069168], <i>vitellogenin-6</i> (<i>vit-6</i>) [Genbank AB084783], <i>forkhead box L2</i> (<i>foxL2</i>) [Genbank AM860211], <i>nanos homolog 3</i> (<i>nanos3</i>) [Genbank CU994694] and <i>regulator of chromosome condensation</i> (<i>rcc1</i>) [Genbank CU996984]. The patterns of transcripts abundance detected for these genes in the array and by real time qPCR showed extremely similar profiles (R² = 0.80). For microarray, only Site 1 samples are shown. Developmental stage (St3: stage 3; St2: stage 2; St1: stage 1; St0: stage 0) and sex (M: male and F: female) are indicated at the bottom of each figure. Bars represent standard deviation.</p

Bilan de la saison 2021 de fièvre West Nile en Europe

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Genes differentially expressed during gametogenesis and their expression in somatic cells or oocytes.

<p>Genes differentially expressed during gametogenesis and their expression in somatic cells or oocytes.</p

Overview of experimental procedures.

<p>Innate immune memory experiments were carry out. For primo-infection, Brazilian <i>Biomphalaria glabrata</i> (BgBRE) snails were individually exposed to 10 miracidia of their sympatric Brazilian <i>Schistosoma mansoni</i> trematode parasite (SmBRE). Following infection depending on the compatibility status of the snail/parasite couples, some of the miracidia were encapsulated by the hemocytes (snail immune cells) or developed into primary sporocysts (intra-molluscan stage of the parasite). Intramolluscan parasite stages include two generations of sporocysts (primary sporocyst (SPI) and secondary sporocyst (SPII)) and the production of cercariae. SPII developed inside SPI and migrated to reach the snail hepato-pancrea. Cercariae developed inside SPI and migrated back into the snail to reach the aquatic environment. Twenty-five days after primo-infection, the snails were challenged for a second time with again 10 SmBRE miracidia. In this case all miracidia degenerated in snail tissues, demonstrating the activation of a humoral immune response. Immune phenotypes observed during innate immune memory process were analyzed using a histological approach (see <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1005361#ppat.1005361.g002" target="_blank">Fig 2A, 2B & 2C</a>). In order to explore the molecular mechanisms of innate immune memory several experimental procedures were designed. A RNAseq experiment was realized with samples recovered from uninfected snails (Naive 1, Naive 2), samples recovered at 1, 4, 15 and 25 days post primo-infection (DPPI) and at 1, 4 and 15 days post-secondary challenge (DPC) (see <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1005361#ppat.1005361.g003" target="_blank">Fig 3</a>). Based on RNaseq results, functional validation of the FREP immune recognition receptor was undergone. First, individual quantification were made for all FREPs annotated on transcriptomic analysis (see <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1005361#ppat.1005361.g004" target="_blank">Fig 4A</a>). FREP knockdown was then carried out by siRNA injection, normalized by siGFP and monitored by Q-RT-PCR (see <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1005361#ppat.1005361.g004" target="_blank">Fig 4B & 4C</a>). Finally, to confirm the involvement of plasmatic factors in innate immune memory, snail hemolymph was recovered (Naive, 15, 25 DPPI and 15 DPC) and plasmatic fraction was characterized by 2D-gel electrophoresis (see <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1005361#ppat.1005361.g005" target="_blank">Fig 5A & 5B</a>). Plasma samples were also injected to naïve snails to demonstrate that immune protection could be acquired following primed snail plasma transfer (see <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1005361#ppat.1005361.g005" target="_blank">Fig 5C</a>).</p