RNA Interference Technology to Control Pest Sea Lampreys - A Proof-of-Concept

Abstract

The parasitic sea lamprey (Petromyzon marinus) has caused extensive losses to commercial fish stocks of the upper Great Lakes of North America. Methods of controlling the sea lamprey include trapping, barriers to prevent migration, and use of a chemical lampricide (3-trifluoromethyl-4-nitrophenol) to kill the filter-feeding larvae. Concerns about the non-specificity of these methods have prompted continued development of species-specific methods to control lampreys outside their native range. In this study, we considered the utility of RNA interference to develop a sea lamprey-specific lampricide. Injection of six different short interfering, double-stranded RNAs (siRNAs) into lamprey embryos first confirmed that the siRNAs could reduce the targeted transcript levels by more than 50%. Two size classes of lamprey larvae were then fed the siRNAs complexed with liposomes, and three of the siRNAs (targeting elongation factor 1α, calmodulin, and α-actinin) reduced transcript levels 2.5, 3.6, and 5.0–fold, respectively, within the lamprey midsections. This is not only the first demonstration of RNAi in lampreys, but it is also the first example of delivery of siRNAs to a non-mammalian vertebrate through feeding formulations. One of the siRNA treatments also caused increased mortality of the larvae following a single feeding of siRNAs, which suggests that prolonged or multiple feedings of siRNAs could be used to kill filter-feeding larvae within streams, following development of a slow-release formulation. The genes targeted in this study are highly conserved across many species, and only serve as a proof-of-concept demonstration that siRNAs can be used in lampreys. Given that RNA interference is a sequence-specific phenomenon, it should be possible to design siRNAs that selectively target gene sequences that are unique to sea lampreys, and thus develop a technology to control these pests without adversely affecting non-target species.

Characterization and identification of calmodulin and calmodulin binding proteins in hemocyte of the black tiger shrimp (Penaeus monodon)

“…Our silencing PmCaM without the pathogen infection showed no effect on shrimp mortality in comparison with the control shrimps. Similarly, in sea lamprey larvae, CaM gene silencing did not effect on the animal mortality (Heath et al, 2014). For other signaling proteins, silencing of Rab7 gene in P. monodon caused less than 5% shrimp mortality in comparison with GFP dsRNA and NaCl injection groups (Ongvarrasopone et al, 2008).…”

The Sea Lamprey as an Etiological Model for Biliary Atresia

“…Current animal models are unable to interrupt the progression of liver disease or improve long-term outcome with the native liver [ 119 ]. With the same ex utero development of large number of larvae, recent annotation of the sea lamprey genome [ 120 ], siRNA technique [ 121 ], a modified tissue clarification method [ 122 ], and advanced liquid chromatography tandem mass spectrometry (LC-MS/MS) bile acid analytical methods [ 123 – 126 ], sea lamprey can provide valuable insights on the molecular mechanisms of BA including the triggering factors for BA, lymphocyte infiltration, fibrogenesis, cholestasis, macrophage activation, and clearance of fibrosis. Utilizing sea lamprey as a BA model will provide much-needed mechanistic insights into the etiology and pathogenesis of BA, specifically the roles of immune system in the initiation and progression of the disease.…”

Functional genetic analysis in a jawless vertebrate, the sea lamprey: insights into the developmental evolution of early vertebrates

“…The long-term viability of both options is uncertain, however, which has prompted the Great Lakes Fishery Commission to explore other possibilities, including genetic biocontrol. In support of the latter, recent developments in gene editing techniques as described above demonstrate that lamprey gene sequences can be edited efficiently, and other genetic techniques such as RNA interference (RNAi) have been used to demonstrate efficient disruption of gene activity in adults (Heath et al, 2014). Transient expression of tissue-specific reporter genes has also been demonstrated in lamprey, allowing for direct tests of the role of different genes in sea lamprey development.…”