The evolution of small RNA pathways and the roles of microRNAs in Cnidaria
MicroRNAs are small RNAs which were discovered initially in nematodes at 1993. A decade later they were also identified in most other animals and in plants and were shown to play crucial roles in the development of many species. MicroRNAs act through a protein effector complex which binds to messenger RNAs in a specific manner via annealing of the microRNA to the mRNA target and affect the target expression levels. I initialized during my postdoc in Vienna a study on the roles of microRNAs in N. vectensis development. This study is still underway but we already obtained some very exciting findings regarding the involvement of microRNAs in the regulation of expression levels of proteins involved in development of the anemone. Moreover, we have interesting results regarding the mechanism of action of microRNAs in cnidarians suggesting new and unexpected links between the microRNA pathways of plants and animals see our papers in MBE and Genome Research about this topic. This project also received much hype (and somewhat disinformative presentation!) in popular media such as here, here (in English) and here (in Hebrew). You can also read our new review in Nature Ecology and Evolution here.
Evolution of sea anemone (and other strange animal) toxins
This is a study I initialized as a PhD student in Tel Aviv University at the lab of Prof. Michael Gurevitz and I pursue it further in my postdoc as a side project (toxinology is a very sad addiction). We published several papers about the unusual evolutionary patterns we discovered in sea anemone and scorpion toxins and speculated regarding the factors driving their selection. In general, animal toxins just like immunology-related proteins are a vast playground for strong adaptive selection as they are involved in a never-ending "arms-race" of prey and predator. We also found evidence for an unusual mode of evolution, called "concerted evolution" in the toxin genes of sea anemones. Further, in a recent paper we also show that the expression of neurotoxins happens in several anemone species such as Nematostella not only in nematocytes (stinging cells) but in gland cells. This finding challenges the common statement presented in many invertebrate zoology textbooks that peptide cnidarian toxins are produced exclusively in nematocytes. The ecological shifts which led to toxin expression in different cell populations of closely-related species are of great interest and open the field to eco-evo studies. We also employed proteomic methods for the study of the venom components of Nematosella nematocytes and recently published those results.
We are nowadays taking advantage on unique tools such as transgenesis techniques that are available in Nematostella for answering questions about the evolution of venom and venom-producing cells.
Evolution of voltage-gated sodium channels
Voltage-gated sodium channels are pivotal components in the conductance of neuronal signals. The unprecedented extent of sequencing of animal genomes in the last few years has enabled us to study in detail the evolution of these channels. We found that these channels have first appeared in unicellular organisms before the split of fungi and animals, but were independently lost in many lineages. Surprisingly cnidarians have a remarkable diversity of channel isoforms, but most of them cannot discern sodium from calcium and potassium. However, Cnidarians do have a selective channel isoform that evolved more than 540 million years ago in the ancestor of all extant cnidarians. The molecular basis of this selectivity is different from that found in selective sodium channels of bilaterians, indicating that sodium selectivity evolved twice independently in animals, probably in order to comply with the rising need for more complex and faster neuronal transmission. In this work we applied both electrophysiological and phylogenetic methods and a first publication came out in Cell Reports. It was followed by a review paper.
Our research is generously funded by the Binational Science Foundation (BSF), the European Research Council (ERC), German-Israeli Foundation for Scientific Research and Development (GIF), the Israel Council of Higher Learning, the Israel Science Foundation (ISF) and the Marie Curie Actions of the European Commission. We are grateful for this support.