Horizontal gene transfer in eukaryotic evolution

Keeling, Patrick J.; Palmer, Jeffrey D.

doi:10.1038/nrg2386

Cited by 1,156 publications

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“…The observation that a gene is uniquely shared by distantly related organisms can be attributed to multiple possible scenarios, in particular differential loss and HGT [19,20]. Although differential loss and HGT can always be invoked as alternative explanations to each other, each scenario becomes increasingly less likely if it requires considerably more corresponding (gene loss or HGT) events [19,21].…”

Section: Resultsmentioning

confidence: 99%

Evidence for acquisition of virulence effectors in pathogenic chytrids

et al. 2011

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BackgroundThe decline in amphibian populations across the world is frequently linked to the infection of the chytrid fungus Batrachochytrium dendrobatidis (Bd). This is particularly perplexing because Bd was only recently discovered in 1999 and no chytrid fungus had previously been identified as a vertebrate pathogen.ResultsIn this study, we show that two large families of known virulence effector genes, crinkler (CRN) proteins and serine peptidases, were acquired by Bd from oomycete pathogens and bacteria, respectively. These two families have been duplicated after their acquisition by Bd. Additional selection analyses indicate that both families evolved under strong positive selection, suggesting that they are involved in the adaptation of Bd to its hosts.ConclusionsWe propose that the acquisition of virulence effectors, in combination with habitat disruption and climate change, may have driven the Bd epidemics and the decline in amphibian populations. This finding provides a starting point for biochemical investigations of chytridiomycosis.

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Section: Resultsmentioning

confidence: 99%

Evidence for acquisition of virulence effectors in pathogenic chytrids

et al. 2011

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“…Many microbial eukaryotes appear to have genomes that are to some extent mosaic, with a significant number of genes laterally acquired, from organisms such as cyanobacteria, proteobacteria, and euglenoids (Keeling and Palmer, 2008;Waller et al, 2006;Wisecaver and Hackett, 2014). The genes sxtA and sxtG appear likely to have been acquired via an ancient transfer from a prokaryote into a dinoflagellate ancestor Orr et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Gene duplication, loss and selection in the evolution of saxitoxin biosynthesis in alveolates

Murray

Diwan

Orr

et al. 2015

Molecular Phylogenetics and Evolution

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a b s t r a c tA group of marine dinoflagellates (Alveolata, Eukaryota), consisting of $10 species of the genus Alexandrium, Gymnodinium catenatum and Pyrodinium bahamense, produce the toxin saxitoxin and its analogues (STX), which can accumulate in shellfish, leading to ecosystem and human health impacts. The genes, sxt, putatively involved in STX biosynthesis, have recently been identified, however, the evolution of these genes within dinoflagellates is not clear. There are two reasons for this: uncertainty over the phylogeny of dinoflagellates; and that the sxt genes of many species of Alexandrium and other dinoflagellate genera are not known. Here, we determined the phylogeny of STX-producing and other dinoflagellates based on a concatenated eight-gene alignment. We determined the presence, diversity and phylogeny of sxtA, domains A1 and A4 and sxtG in 52 strains of Alexandrium, and a further 43 species of dinoflagellates and thirteen other alveolates. We confirmed the presence and high sequence conservation of sxtA, domain A4, in 40 strains (35 Alexandrium, 1 Pyrodinium, 4 Gymnodinium) of 8 species of STX-producing dinoflagellates, and absence from non-producing species. We found three paralogs of sxtA, domain A1, and a widespread distribution of sxtA1 in non-STX producing dinoflagellates, indicating duplication events in the evolution of this gene. One paralog, clade 2, of sxtA1 may be particularly related to STX biosynthesis. Similarly, sxtG appears to be generally restricted to STX-producing species, while three amidinotransferase gene paralogs were found in dinoflagellates. We investigated the role of positive (diversifying) selection following duplication in sxtA1 and sxtG, and found negative selection in clades of sxtG and sxtA1, clade 2, suggesting they were functionally constrained. Significant episodic diversifying selection was found in some strains in clade 3 of sxtA1, a clade that may not be involved in STX biosynthesis, indicating pressure for diversification of function.

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“…However, the importance of this process in eukaryotic evolution has been questioned (except for gene transfers from mitochondria and plastid ancestors to the eukaryotic nucleus [4,5]) considering the barriers imposed on the spread of horizontally acquired genes by the presence of the germ line.…”

Section: Introductionmentioning

confidence: 99%

Horizontal gene transfer in the acquisition of novel traits by metazoans

2014

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Horizontal gene transfer is accepted as an important evolutionary force modulating the evolution of prokaryote genomes. However, it is thought that horizontal gene transfer plays only a minor role in metazoan evolution. In this paper, I critically review the rising evidence on horizontally transferred genes and on the acquisition of novel traits in metazoans. In particular, I discuss suspected examples in sponges, cnidarians, rotifers, nematodes, molluscs and arthropods which suggest that horizontal gene transfer in metazoans is not simply a curiosity. In addition, I stress the scarcity of studies in vertebrates and other animal groups and the importance of forthcoming studies to understand the importance and extent of horizontal gene transfer in animals.

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Horizontal gene transfer in eukaryotic evolution

Cited by 1,156 publications

References 156 publications

Evidence for acquisition of virulence effectors in pathogenic chytrids

Evidence for acquisition of virulence effectors in pathogenic chytrids

Gene duplication, loss and selection in the evolution of saxitoxin biosynthesis in alveolates

Horizontal gene transfer in the acquisition of novel traits by metazoans

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