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Batrachochytrium dendrobatidis(Bd), a causative agent of chytridiomycosis, is decimating amphibian populations around the world.Bdbelongs to the chytrid lineage, a group of early-diverging fungi that are widely used to study fungal evolution. Like all chytrids,Bddevelops from a motile form into a sessile, growth form, a transition that involves drastic changes in its cytoskeletal architecture. Efforts to studyBdcell biology, development, and pathogenicity have been limited by the lack of genetic tools with which to test hypotheses about underlying molecular mechanisms. Here, we report the development of a transient genetic transformation system forBd. We used electroporation to deliver exogenous DNA intoBdcells and detected transgene expression for up to three generations under both heterologous and native promoters. We also adapted the transformation protocol for selection using an antibiotic resistance marker. Finally, we used this system to express fluorescent protein fusions and, as a proof of concept, expressed a genetically encoded probe for the actin cytoskeleton. Using live-cell imaging, we visualized the distribution and dynamics of polymerized actin at each stage of theBdlife cycle, as well as during key developmental transitions. This transformation system enables direct testing of key hypotheses regarding mechanisms ofBdpathogenesis. This technology also paves the way for answering fundamental questions of chytrid cell, developmental, and evolutionary biology. 

Chytrid fungi play key ecological roles in aquatic ecosystems, and some species cause a devastating skin disease in frogs and salamanders. Additionally, chytrids occupy a unique phylogenetic position– sister to the well-studied Dikarya (the group including yeasts, sac fungi, and mushrooms) and related to animals– making chytrids useful for answering important evolutionary questions. Despite their importance, little is known about the basic cell biology of chytrids. A major barrier to understanding chytrid biology has been a lack of genetic tools with which to test molecular hypotheses. Medina and colleagues recently developed a protocol for Agrobacterium -mediated transformation of Spizellomyces punctatus . In this manuscript, we describe the general procedure including planning steps and expected results. We also provide in-depth, step-by-step protocols and video guides for performing the entirety of this transformation procedure on protocols.io (dx.doi.org/10.17504/protocols.io.x54v9dd1pg3e/v1). 

Understanding the origin of eukaryotic cells is one of the most difficult problems in all of biology. A key challenge relevant to the question of eukaryogenesis is reconstructing the gene repertoire of the last eukaryotic common ancestor (LECA). As data sets grow, sketching an accurate genomics-informed picture of early eukaryotic cellular complexity requires provision of analytical resources and a commitment to data sharing. Here, we summarise progress towards understanding the biology of LECA and outline a community approach to inferring its wider gene repertoire. Once assembled, a robust LECA gene set will be a useful tool for evaluating alternative hypotheses about the origin of eukaryotes and understanding the evolution of traits in all descendant lineages, with relevance in diverse fields such as cell biology, microbial ecology, biotechnology, agriculture, and medicine. In this Consensus View, we put forth the status quo and an agreed path forward to reconstruct LECA’s gene content. 

Abstract The chytrid fungusBatrachochytrium dendrobatidis(Bd) is a causative agent of chytridiomycosis, a skin disease associated with amphibian population declines around the world. Despite the major impactBdis having on global ecosystems, much ofBd’s basic biology remains unstudied. In addition to revealing mechanisms driving the spread of chytridiomycosis, studyingBdcan shed light on the evolution of key fungal traits because chytrid fungi, includingBd, diverged before the radiation of the Dikaryotic fungi (multicellular fungi and yeast). StudyingBdin the laboratory is, therefore, of growing interest to a wide range of scientists, ranging from herpetologists and disease ecologists to molecular, cell, and evolutionary biologists. This protocol describes how to maintain developmentally synchronized liquid cultures ofBdfor use in the laboratory, how to growBdon solid media, as well as cryopreservation and revival of frozen stocks. © 2021 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Reviving cryopreservedBdcultures Basic Protocol 2: Establishing synchronized liquid cultures ofBd Basic Protocol 3: Regular maintenance of synchronousBdin liquid culture Alternate Protocol 1: Regular maintenance of asynchronousBdin liquid culture Basic Protocol 4: Regular maintenance of synchronousBdon solid medium Alternate Protocol 2: Starting a culture on solid medium from a liquid culture Basic Protocol 5: Cryopreservation ofBd