A complex of polypeptides derived from a precursor is present on the surface of the malaria merozoite. During erythrocyte invasion only a small fragment from this complex is retained on the parasite surface and carried into the newly infected red cell. Antibodies to this fragment will interrupt invasion.

The Opisthokonta are a eukaryotic supergroup divided in two main lineages: animals and related protistan taxa, and fungi and their allies [1, 2]. There is a great diversity of lifestyles and morphologies among unicellular opisthokonts, from free-living phagotrophic flagellated bacterivores and filopodiated amoebas to cell-walled osmotrophic parasites and saprotrophs. However, these characteristics do not group into monophyletic assemblages, suggesting rampant convergent evolution within Opisthokonta. To test this hypothesis, we assembled a new phylogenomic dataset via sequencing 12 new strains of protists. Phylogenetic relationships among opisthokonts revealed independent origins of filopodiated amoebas in two lineages, one related to fungi and the other to animals. Moreover, we observed that specialized osmotrophic lifestyles evolved independently in fungi and protistan relatives of animals, indicating convergent evolution. We therefore analyzed the evolution of two key fungal characters in Opisthokonta, the flagellum and chitin synthases. Comparative analyses of the flagellar toolkit showed a previously unnoticed flagellar apparatus in two close relatives of animals, the filasterean Ministeria vibrans and Corallochytrium limacisporum. This implies that at least four different opisthokont lineages secondarily underwent flagellar simplification. Analysis of the evolutionary history of chitin synthases revealed significant expansions in both animals and fungi, and also in the Ichthyosporea and C. limacisporum, a group of cell-walled animal relatives. This indicates that the last opisthokont common ancestor had a complex toolkit of chitin synthases that was differentially retained in extant lineages. Thus, our data provide evidence for convergent evolution of specialized lifestyles in close relatives of animals and fungi from a generalist ancestor.

Which genomic innovations underpinned the origin of multicellular animals is still an open debate. Here, we investigate this question by reconstructing the genome architecture and gene family diversity of ancestral premetazoans, aiming to date the emergence of animal-like traits. Our comparative analysis involves genomes from animals and their closest unicellular relatives (the Holozoa), including four new genomes: three Ichthyosporea and Corallochytrium limacisporum. Here, we show that the earliest animals were shaped by dynamic changes in genome architecture before the emergence of multicellularity: an early burst of gene diversity in the ancestor of Holozoa, enriched in transcription factors and cell adhesion machinery, was followed by multiple and differently-timed episodes of synteny disruption, intron gain and genome expansions. Thus, the foundations of animal genome architecture were laid before the origin of complex multicellularity – highlighting the necessity of a unicellular perspective to understand early animal evolution.DOI: http://dx.doi.org/10.7554/eLife.26036.001

We report a ribosomal tag pyrosequencing study of the phylogenetic diversity of Archaea, Bacteria and Eucarya over a depth profile at the Hawaii Ocean Time-Series Station, ALOHA. The V9 region of the SSU rRNA gene was amplified from samples representing the epi-(10 m), meso-(800 m) and bathy-(4400 m) pelagia. The primers used are expected to amplify representatives of B80% of known phylogenetic diversity across all three domains. Comparisons of unique sequences revealed a remarkably low degree of overlap between communities at each depth. The 444 147 sequence tags analyzed represented 62 975 unique sequences. Of these, 3707 (5.9%) occurred at two depths, and only 298 (0.5%) were observed at all three depths. At this level of phylogenetic resolution, Bacteria diversity decreased with depth but was still equivalent to that reported elsewhere for different soil types. Archaea diversity was highest in the two deeper samples. Eucarya observations and richness estimates are almost one order of magnitude higher than any previous marine microbial Eucarya richness estimates. The associations of many Eucarya sequences with putative parasitic organisms may have significant impacts on our understanding of the mechanisms controlling host population density and diversity, and point to a more significant role for microbial Eucarya in carbon flux through the microbial loop. We posit that the majority of sequences detected from the deep sea that have closest matches to sequences from non-pelagic sources are indeed native to the marine environment, and are possibly responsible for key metabolic processes in global biogeochemical cycles.