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Biomphalaria glabratais a fresh-water mollusk that serves as obligatory intermediate host toSchistosoma mansoni, agent of the neglected tropical disease schistosomiasis that affects roughly 250 Mio people. One of the ways to control the pathogenic agent is to interrupt the life cycle by eliminating the intermediate snail host though foal treatment of water bodies with molluscicides. Currently recommended molluscicides were developed in the 1950ths and lack sufficient specificity, e.g., they are toxic to fish. To provide new lead compounds for the development of a new type of molluscicides we used a rational approach based on the hypotheses that interfering with an important epigenetic mark, DNA methylation, would impede development of the snail host. We present here the compound 29, analogues-based compound that mimic substrates of DNA methyltransferases. We show that compound 29 has (i) low cytotoxicity for human cells, (ii) it inhibits DNA methylation, and (iii) it decreases fecundity inB.glabrata. It is therefore conceivable to produce compounds that act as specific epigenetic molluscicides.

Background 5-Methylcytosine (5mC) is an important epigenetic mark in eukaryotes. Little information about its role exists for invertebrates. To investigate the contribution of 5mC to phenotypic variation in invertebrates, alteration of methylation patterns needs to be produced. Here, we apply new non-nucleoside DNA methyltransferase inhibitors (DNMTi) to introduce aleatory changes into the methylome of mollusk species. Results Flavanone inhibitor Flv1 was efficient in reducing 5mC in the freshwater snails Biomphalaria glabrata and Physa acuta, and to a lesser degree, probably due to lower stability in sea water, in the oyster Crassostrea gigas. Flv1 has no toxic effects and significantly decreased the 5mC level in the treated B. glabrata and in its offspring. Drug treatment triggers significant variation in the shell height in both generations. A reduced representation bisulfite-sequencing method called epiGBS corroborates hypomethylation effect of Flv1 in both B. glabrata generations and identifies seven Differential Methylated Regions (DMR) out of 32 found both in Flv1-exposed snails and its progeny, from which 5 were hypomethylated, demonstrating a multigenerational effect. By targeted bisulfite sequencing, we confirmed hypomethylation in a locus and show that it is associated with reduced gene expression. Conclusions Flv1 is a new and efficient DNMTi that can be used to induce transient and heritable modifications of the epigenetic landscape and phenotypic traits in mollusks, a phylum of the invertebrates in which epigenetics is understudied.

International audience; The phenotypic plasticity of plants in response to change in their light environment, and in particularly, to shade is a schoolbook example of ecologically relevant phenotypic plasticity with evolutionary adaptive implications. Epigenetic variation is known to potentially underlie plant phenotypic plasticity. Yet, little is known about its role in ecologically and evolutionary relevant mechanisms shaping the diversity of plant populations in nature. Here we used a reference-free reduced representation bisulfite sequencing method for non-model organisms (epiGBS) to investigate changes in DNA methylation patterns across the genome in snapdragon plants (Antirrhinum majus L.). We exposed plants to sunlight versus artificially induced shade in four highly inbred lines to exclude genetic confounding effects. Our results showed that phenotypic plasticity in response to light versus shade shaped vegetative traits. They also showed that DNA methylation patterns were modified under light versus shade, with a trend towards global effects over the genome but with large effects found on a restricted portion. We also detected the existence of a correlation between phenotypic and epigenetic variation that neither supported nor rejected its potential role in plasticity. While our findings imply epigenetic changes in response to light versus shade environments in snapdragon plants, whether these changes are directly involved in the phenotypic plastic response of plants remains to be investigated. Our approach contributed to this new finding but illustrates the limits in terms of sample size and statistical power of population epigenetic approaches in non-model organisms. Pushing this boundary will be necessary before the relationship between environmentally induced epigenetic changes and phenotypic plasticity is clarified for ecologically relevant mechanisms with evolutionary implications

The study of epigenetic changes in natural and experimental populations has increased the need to find a cost-effective and high throughput method to analyze multiple samples to effectuate a population-wide screening to study epigenetic changes triggered by biotic or abiotic stress. One of the most studied epigenetic marks is global DNA methylation, its measurement is used as a first step to differentiate methylation between individuals. There is a wide range of methods designed to detect genome-wide 5 methyl-cytosine (5mC) that differ in sensitivity, price, level of expertise required, but as a general rule, require large amounts of DNA and are relatively expensive. This is a limit for the analysis of 5mC in a large number of individuals as a prerequisite to population-wide testing of methylation markers. In this work, we evaluated a method based on antibody recognition of 5mC to measure the DNA methylation level of individuals of the species Biomphalaria glabrata, the intermediate host of schistosomiases, a neglected tropical disease. We validated the method to complete a large screening in the genome of B. glabrata snails treated with a chemical inhibitor of DNA methylation; however, the method can be applied to any species containing 5mC. The dot blot assay is a suitable method to perform a large-scale screening of global DNA methylation to compare 5mC levels between individuals from different natural or experimental populations. The dot blot method compares favorably with methods with an equivalent sensitivity such as the Enzyme Linked Immunosorbent Assay (ELISA) kit since it requires a smaller amount of DNA (30 ng) is less expensive and allows many more samples to be analyzed.

Schistosomiasis is an important parasitic disease, touching roughly 200 million people worldwide. The causative agents are different Schistosoma species. Schistosomes have a complex life cycle, with a freshwater snail as intermediate host. After infection, sporocysts develop inside the snail host and give rise to human dwelling larvae. We present here a detailed step-by-step video instruction in English, French, Spanish and Portuguese that shows how these sporocysts can be manipulated and transferred from one snail to another. This procedure provides a technical basis for different types of ex vivo modifications, such as those used in functional genomics studies.

ResumenSe presenta el registro de las especies de invertebrados marinos que habitan la costa rocosa intermareal de Montepío, Veracruz, identificados hasta ahora. La información se obtuvo de las colectas realizadas en los últimos 10 años por parte de la Colección Nacional de Crustáceos y los registros adicionales se obtuvieron de la información publicada. El listado de especies incluye las formas de vida en relación con el sustrato, criptofauna o epifauna, así como su tipo de distribución en las 2 principales regiones zoogeográficas marinas para el golfo de México: Carolineana y Caribeña; se incluyen también las especies que sólo se encuentran en el golfo de México. El listado incluye 195 especies pertenecientes a 9 grupos, de los cuales Crustacea es el más diverso con 73 especies, seguido por Mollusca con 69 y Echinodermata con 18; los grupos con menor riqueza específica fueron: Chelicerata con 2 especies y Platyhelminthes y Sipuncula con una sola especie cada grupo. Del total de especies 74 son nuevos registros de localidad y 7 nuevos registros para Veracruz. Para la porción mexicana del golfo de México se han reportado 5 517 especies de invertebrados, y se estima entonces que el 3.5% de este total se puede encontrar en Montepío. La epifauna presentó mayor riqueza específica (70%) que la criptofauna (30%), que se compone principalmente de moluscos, poliquetos y sipuncúlidos. Se observó una mayor afinidad tropical en la composición de especies obtenida; sin embargo, un número importante de especies presenta una afinidad subtropical o Carolineana (86) y 51 especies se distribuyen únicamente en el golfo de México.AbstractA list of the marine invertebrate species identified until now from the rocky intertidal shore at Montepío, Veracruz, is presented. The information was obtained from 10 years of collections made by the Colección Nacional de Crustáceos and additional records were compiled from published information. The species list includes the life form in relation to the substrate, epifauna or criptofauna, as well as its type of distribution considering the 2 main zoogeographic provinces recognized for the Gulf of Mexico: Carolinean and Caribbean; the species found only in the Gulf of Mexico are also noted. The list includes 195 species belonging to 9 groups of which Crustacea is the most diverse with 73 species, followed by Mollusca with 69 and Echinodermata with 18; the less diverse groups were Chelicerata with 2 species and Platyhelminthes and Sipuncula with 1 species each. Seventy-four species represent new locality records and 7 are new records for Veracruz. A total of 5 517 invertebrate species have been reported for the Mexican portion of the Gulf of Mexico, thus 3.5% of this total can be found in Montepio. More species were part of the epifauna (70%) than the criptofauna (30%) which is composed mainly by molluscs, polychaetes and sipunculids. A larger tropical affinity was observed in the obtained species composition; however, an important number of species are more subtropical or Carolinean (86) and 51 species occur only in the Gulf of Mexico.