Cytokinin Perception in Ancient Plants beyond Angiospermae

Cytokinins (CKs) control many plant developmental processes and responses to environmental cues. Although the CK signaling is well understood, we are only beginning to decipher its evolution. Here, we investigated the CK perception apparatus in early-divergent plant species such as bryophyte Physcomitrium patens, lycophyte Selaginella moellendorffii, and gymnosperm Picea abies. Of the eight CHASE-domain containing histidine kinases (CHKs) examined, two CHKs, PpCHK3 and PpCHK4, did not bind CKs. All other CHK receptors showed high-affinity CK binding (KD of nM range), with a strong preference for isopentenyladenine over other CK nucleobases in the moss and for trans-zeatin over cis-zeatin in the gymnosperm. The pH dependences of CK binding for these six CHKs showed a wide range, which may indicate different subcellular localization of these receptors at either the plasma- or endoplasmic reticulum membrane. Thus, the properties of the whole CK perception apparatuses in early-divergent lineages were demonstrated. Data show that during land plant evolution there was a diversification of the ligand specificity of various CHKs, in particular, the rise in preference for trans-zeatin over cis-zeatin, which indicates a steadily increasing specialization of receptors to various CKs. Finally, this distinct preference of individual receptors to different CK versions culminated in vascular plants, especially angiosperms.

Paleobotany collections: fossil woods available at the Bandung Geological Museum

Indonesia is a country which has plants species diversity. The form of ancient plants that grew in the past are recorded as fossil woods. Several fossil woods from regions in Indonesia were collected and became exhibition collections at the Bandung Geological Museum. These fossil woods on display requires biology identity to provide more information to visitors. Identification of species of fossil woods were carried out based on the anatomical features on the smoothed cross-section. Observations were carried out by a loop hand (a magnification of 10 times and a digital loop (with a magnification of 16 times). The fossil woods anatomy features observed included vessel cells, parenchyma cells, rays cells, and the presence of resin channels. The fossil specimen which had unclear anatomy features compared by detailed description of wood anatomy available at the library and collections of wood samples owned by the Xylarium Bogoriense. The fossil woods species are Canarioxylon sp., Terminalioxylon sp., Anisopteroxylon sp., Dipterocarpoxylon sp., Dryobalanoxylon sp., Hopenium/Hopeoxylon sp., Shoreoxylon sp., Kompassioxylon sp., and Xanthophyllum sp. The mostly fossil woods species resvectively belonging to the Dipterocarpaceae, Combretaceae, Polygalaceae, Burseraceae, and Leguminosae. The fossil woods member of Dipterocarpaceae family are conspicuously characterized with the presence of resin canals.

The structure of the Physcomitrium Patens Photosystem I Reveals a Unique Lhca2 Paralogue replacing Lhca4

The moss Physcomitrium patens diverged from green algae shortly after the colonization of land by ancient plants. This colonization posed new environmental challenges which drove evolutionary processes. The photosynthetic machinery of modern flowering plants is adapted to the high light conditions on land. Red shifted Lhca4 antennae are present in the photosystem I light harvesting complex of many green lineage plants but absent from P. patens. The Cryo-EM structure of the P. patens photosystem I light harvesting complex I supercomplex (PSI-LHCI) at 2.8 Å reveals that Lhca4 is replaced by a unique Lhca2 paralogue in moss. This PSI-LHCI supercomplex also retains the PsaM subunit, present in cyanobacteria and several algal species but lost in higher plants, and the PsaO subunit responsible for binding light harvesting complex II. The blue shifted Lhca2 paralogue and chlorophyll b enrichment relative to higher plants make the P. patens PSI-LHCI spectroscopically unique among other green lineage supercomplexes. Overall, the structure represents an evolutionary intermediate PSI with the crescent shaped LHCI common in higher plants and contains a unique Lhca2 paralogue which facilitates the mosses adaptation to low light niches.

Pleistocene Park, and other designs on deep time in the Interwar United States

Precisely how to reconstruct the planetary past is not predetermined. This article compares three contemporary plans, dreamed up in the United States during the Interwar and Depression years, that deploy diverse techniques to evoke extinct environments. Building on Martin Rudwick's historicization of ‘scenes from deep time’, this article develops the concept of designs on deep time to explain how public displays of the planetary past circulate anything-but-neutral ideas about past and present to awed audiences. By detailing three contemporary designs on deep time—Pleistocene Park at the La Brea Tar Pits, a sensational World's Fair exhibit called ‘The World a Million Years Ago’, and a dinosaur park where living fossils and ancient plants approximated a Mesozoic atmosphere—this article captures diverse philosophies about how to construct persuasive encounters with the prehistoric past. It also demonstrates how, despite disparate approaches, these designers of deep time displays all used the planetary past to legitimate present regimes and foster faith in human progress. During the 1920s and 1930s, when the wounds of war, changing demographics, and economic depression collaborated to dispute a prevailing myth of American progress, deep time by design buoyed faith in a better future.

Paleozoic fossil plants of the north-east of the European part of Russia in the collections of the A. A. Chernov Geological museum

The article is devoted to the history of the study of fossil algae and plants in the Paleozoic sedimentary deposits developed in the north-east of the European part of Russia. The main locations of the fossilized flora in this area are indicated. The history of the study shows that the remains of ancient plants and algae have been studied unevenly, which is due to the nature of the distribution of the remains and their preservation, as well as the lack of specialists. The generalization of the available information made it possible to present a collection of fossil algae and plant remains of the Paleozoic in the A. A. Chernov Geological Museum, which are of scientific and educational interest.

Microbial biomarkers reveal a hydrothermally active landscape at Olduvai Gorge at the dawn of the Acheulean, 1.7 Ma

Landscape-scale reconstructions of ancient environments within the cradle of humanity may reveal insights into the relationship between early hominins and the changing resources around them. Many studies of Olduvai Gorge during Pliocene–Pleistocene times have revealed the presence of precession-driven wet–dry cycles atop a general aridification trend, though may underestimate the impact of local-scale conditions on early hominins, who likely experienced a varied and more dynamic landscape. Fossil lipid biomarkers from ancient plants and microbes encode information about their surroundings via their molecular structures and composition, and thus can shed light on past environments. Here, we employ fossil lipid biomarkers to study the paleolandscape at Olduvai Gorge at the emergence of the Acheulean technology, 1.7 Ma, through the Lower Augitic Sandstones layer. In the context of the expansion of savanna grasslands, our results represent a resource-rich mosaic ecosystem populated by groundwater-fed rivers, aquatic plants, angiosperm shrublands, and edible plants. Evidence of a geothermally active landscape is reported via an unusual biomarker distribution consistent with the presence of hydrothermal features seen today at Yellowstone National Park. The study of hydrothermalism in ancient settings and its impact on hominin evolution has not been addressed before, although the association of thermal springs in the proximity of archaeological sites documented here can also be found at other localities. The hydrothermal features and resources present at Olduvai Gorge may have allowed early hominins to thermally process edible plants and meat, supporting the possibility of a prefire stage of human evolution.

A comprehensive study on chloroplast RNA editing by performing a broad-spectrum RNA-seq analysis

Background RNA editing is a post-transcriptional modification that complement variation at the DNA level. Until now, different RNA editing systems were found in the major eukaryotic lineages. However, the evolution trajectory in plant chloroplast remains unclear. To gain a better understanding of RNA editing in plant chloroplast, in this study, based on publicly available RNA-seq data across three clades (fern, gymnosperm, and angiosperm), we provided a detailed analysis of RNA editing events in plant chloroplasts and discussed the evolution of RNA editing in land plants. Results There were a total of 5,389 editing sites located in leaf chloroplast identified across 21 plants after rigorous screening. We found that the cluster of RNA editing sites across 21 plants complied with the phylogenetic tree based on linked protein sequences approximately, there is a common phenomenon that more editing sites occurred in ancient plants for all the three clades. Statistics results revealed that majority (~ 95%) of the editing events resulted in non-synonymous codon changes, RNA editing occurred in second codon position was mainly the largest, and RNA editing caused an overall increase in hydrophobicity of the resulting proteins. The analyses also revealed that there was an uneven distribution of editing sites among species, genes, and codon positions, the average RNA editing extent varied among different plants as well as genes, a lowest RNA editing extent (0.43) was detected in Selaginella moellendorffii. Finally, we found that the loss of editing sites along angiosperm evolution is mainly occurring by reduce of cytosines content, where fern plants has the highest cytosine content. Conclusions Many of the RNA sites identified in our study have not been previously reported and provide a valuable data set for future research community. Our findings also provide valuable information for evolution of RNA editing in plants.

LIR Motif-Containing Hyperdisulfide β-Ginkgotide is Cytoprotective, Adaptogenic, and Scaffold-Ready

Grafting a bioactive peptide onto a disulfide-rich scaffold is a promising approach to improve its structure and metabolic stability. The ginkgo plant-derived β-ginkgotide β-gB1 is a highly unusual molecule: Small, hyperdisulfide, and found only in selected ancient plants. It also contains a conserved 16-amino-acid core with three interlocking disulfides, as well as a six-amino-acid inter-cysteine loop 2 suitable for grafting peptide epitopes. However, very little is known about this recently-discovered family of molecules. Here, we report the biophysical and functional characterizations of the β-ginkgotide β-gB1 from G. biloba. A circular dichroism spectroscopy analysis at 90 °C and proteolytic treatments of β-gB1 supported that it is hyperstable. Data mining revealed that the β-gB1 loop 2 contains the canonical LC3 interacting region (LIR) motif crucial for selective autophagy. Cell-based assays and pull-down experiments showed that β-gB1 is an adaptogen, able to maintain cellular homeostasis through induced autophagosomes formation and to protect cells by targeting intracellular proteins from stress-mediated damage against hypoxia and the hypoxia-reoxygenation of induced cell death. This is the first report of an LIR-containing peptide natural product. Together, our results suggest that the plant-derived β-ginkgotide is cytoprotective, capable of targeting intracellular proteins, and holds promise as a hyperdisulfide scaffold for engineering peptidyl therapeutics with enhanced structural and metabolic stability.