Gene silencing inFucusembryos: developmental consequences ofRNAi‐mediated cytoskeletal disruption

Abstract

Brown algae (Phaeophyceae) are an important algal class that play a range of key ecological roles. They are often important components of rocky shore communities. A number of members of the Fucales and Ectocarpales have provided models for the study of multicellular evolution, reproductive biology and polarized development. Indeed the fucoid algae exhibit the unusual feature of inducible embryo polarization, allowing many classical studies of polarity induction. The potential of further studies of brown algae in these important areas has been increasingly hindered by the absence of tools for manipulation of gene expression that would facilitate further mechanistic analysis and gene function studies at a molecular level. The aim of this study was to establish a method that would allow the analysis of gene function through RNAi-mediated gene knockdown. We show that injection of double-stranded RNA (dsRNA) corresponding to an α-tubulin gene into Fucus serratus Linnaeus zygotes induces the loss of a large proportion of the microtubule cytoskeleton, leading to growth arrest and disruption of cell division. Injection of dsRNA targeting β-actin led to reduced rhizoid growth, enlarged cells and the failure to develop apical hair cells. The silencing effect on actin expression was maintained for 3 months. These results indicate that the Fucus embryo possesses a functional RNA interference system that can be exploited to investigate gene function during embryogenesis.

DISTAG/TBCCd1 Is Required for Basal Cell Fate Determination in Ectocarpus

“…A protocol for genetic transformation does not exist for Ectocarpus (or for any other brown alga) but injection of double stranded RNA into zygotes of the brown alga Fucus has been shown to induce an RNA interference (RNAi) response, leading to knockdown of target gene expression (Farnham et al, 2013). We recently adapted this Fucus RNAi protocol for Ectocarpus, using synthetic siRNA molecules instead of long double-stranded RNA molecules and a lipofectant specifically adapted for dsRNA delivery to introduce the siRNAs into the cell rather than the microinjection procedure used for Fucus (Macaisne et al, 2017).…”

Abiotic regulation of growth and fertility in the sporophyte of Dictyota dichotoma (Hudson) J.V. Lamouroux (Dictyotales, Phaeophyceae)

“…Most of the research has focused on members of the Fucales. Despite promising technologies for molecular gene function analysis and forward genetics being developed recently (Farnham et al 2013), the use of fucoid algae in developmental biology has dwindled over the years, largely because of the poor amenability to genetic and molecular studies (Yang 2008). Because it is easily cultured (Vielhaben 1963;Müller 1962;Kumke 1973), Dictyota has been proposed as a possible model complementary to fucoids (Bogaert et al 2013).…”

The Ectocarpus IMMEDIATE UPRIGHT gene encodes a member of a novel family of cysteine-rich proteins with an unusual distribution across the eukaryotes

“…Recent work has demonstrated that injection of double-stranded RNA into zygotes of the brown alga Fucus induces an RNA interference (RNAi) response, leading to knockdown of target gene expression (Farnham et al, 2013). RNAi therefore represents a potential approach to investigate gene function in brown algae, but a modification to the Fucus protocol was required because microinjection is not feasible for Ectocarpus due to the small size of its cells.…”