Plant-on-chip: Core morphogenesis processes in the tiny plant Wolffia australiana.

A plant can be thought of as a colony comprising numerous growth buds, each developing to its own rhythm. Such lack of synchrony impedes efforts to describe core principles of plant morphogenesis, dissect the underlying mechanisms, and identify regulators. Here, we use the minimalist known angiosperm to overcome this challenge and provide a model system for plant morphogenesis. We present a detailed morphological description of the monocot Wolffia australiana, as well as high-quality genome information. Further, we developed the plant-on-chip culture system and demonstrate the application of advanced technologies such as single-nucleus RNA-sequencing, protein structure prediction, and gene editing. We provide proof-of-concept examples that illustrate how W. australiana can decipher the core regulatory mechanisms of plant morphogenesis.

Single-cell transcriptome sequencing of rumen ciliates provides insight into their molecular adaptations to the anaerobic and carbohydrate-rich rumen microenvironment.

Rumen ciliates are a specialized group of ciliates exclusively found in the anaerobic, carbohydrate-rich rumen microenvironment. However, the molecular and mechanistic basis of the physiological and behavioral adaptation of ciliates to the rumen microenvironment is undefined. We used single-cell transcriptome sequencing to explore the adaptive evolution of three rumen ciliates: two entodiniomorphids, Entodinium furca and Diplodinium dentatum; and one vestibuliferid, Isotricha intestinalis. We found that all three species are members of monophyletic orders within the class Litostomatea, with E. furca and D. dentatum in Entodiniomorphida and I. intestinalis in Vestibuliferida. The two entodiniomorphids might use H2-producing mitochondria and the vestibuliferid might use anaerobic mitochondria to survive under strictly anaerobic conditions. Moreover, carbohydrate-active enzyme (CAZyme) genes were identified in all three species, including cellulases, hemicellulases, and pectinases. The evidence that all three species have acquired prokaryote-derived genes by horizontal gene transfer (HGT) to digest plant biomass includes a significant enrichment of gene ontology categories such as cell wall macromolecule catabolic process and carbohydrate catabolic process and the identification of genes in common between CAZyme and HGT groups. These findings suggest that HGT might be an important mechanism in the adaptive evolution of ciliates to the rumen microenvironment.

Insights into the origin and evolution of Peritrichia (Oligohymenophorea, Ciliophora) based on analyses of morphology and phylogenomics.

Peritrichia is a large and distinctive assemblage of ciliated protists that was first observed by Antonie van Leeuwenhoek over 340 years ago. In the last two decades the evolutionary relationships of this subclass have been increasingly debated as morphological and molecular analyses have generated contrasting conclusions. In this study, we provide genomic-scale data from 12 typical representatives. We combine taxon- and gene-rich phylogenomic analyses, with up to 151 genes (43,956 amino acid residues) from 18 freshwater, brackish and marine isolates in order to assess the systematics and evolutionary history of the Peritrichia. The main findings were: (1) the subclass Peritrichia originates from the end of the Proterozoic to the Cambrian; (2) the monophyletic Peritrichia is sister to the Peniculia (represented by Paramecium) within the class Oligohymenophorea; (3) spasmin plays a significant role in peritrich evolution: we detected the spasmin gene in target ciliates and traced the molecular evolution of spasmin, a key spasmoneme component, together with phylogenetic relationships and morphology of the peritrichs. These findings provide evidence that spasmin is an important molecule to illustrate the phylogenetic position of Peritrichia within the class Oligohymenophorea, the monophyly of Peritrichia, and the diverse and rapid evolution of sessilid peritrichs.

Morphology of Nyctotheroides hubeiensis Li et al. 1998 from Frog Hosts with Molecular Phylogenetic Study of Clevelandellid Ciliates (Armophorea, Clevelandellida).

The morphology of Nyctotheroides hubeiensis (Acta Hydrobiol. Sin. 1998, 22(suppl.):187), collected from the rectum of Phelophylax nigromaculatus, is presented in this paper based on detailed morphological information and molecular data. Our phylogenetic analysis showed that N. hubeiensis fell into the Nyctotheroides clade, which was strongly supported as monophyletic and clustered as basal to the genera Nyctotherus and Clevelandella. Also, the monophyly of the Order Clevelandellida and the affinity of parasitic nyctotherids and free-living metopids were indicated in our work. The origin of clevelandellid ciliates as well as their possible evolutionary history was also discussed here; however, the analysis of more species from other vertebrate hosts (fish, reptiles) should be made before a well-supported conclusion can be drawn.