Intact ribosomal DNA arrays of Potentilla origin detected in Erythronium nucleus suggest recent eudicot-to-monocot horizontal transfer

Comparative Study of Two Erythronium sibiricum Bulb Polysaccharide Fractions in Alleviating Airway Remodeling by Affecting Autophagy and Apoptosis

Erythronium sibiricum (E. sibiricum), which is an indigenous herb in China, is gathered and consumed by nomads in Xinjiang due to its medicinal value. Only a few studies have evaluated its possible pharmacological activity. This study aims to examine and compare the ways in which two E. sibiricum bulb polysaccharide fractions (ESBP and E1P) alleviate airway remodeling based on apoptosis and autophagy. In a mouse model of chronic asthma produced by ovalbumin, the anti-asthmatic effects of E1P and ESBP were investigated. The expression levels of the proteins linked to autophagy and apoptosis (cleaved-caspase 3, Beclin1, LC3B, Bad, and Bax) as well as the activity of the PI3K/Akt/mTOR signaling pathway were assessed. Airway remodeling was alleviated by E1P and ESBP. While E1P could only prevent the increase in PI3K, ESBP was capable of inhibiting the PI3K/Akt/mTOR signaling pathway. Furthermore, ESBP decreased the levels of cleaved-caspase 3, Beclin1, LC3B, Bad, and Bax protein expressions. By modifying signaling pathways linked to autophagy and apoptosis, E. sibiricum bulb polysaccharides successfully improved the airway remodeling of asthma. Additionally, ESBP exhibited more potent inhibitory effects on asthmatic defective autophagy than E1P.

Intragenomic rDNA variation - the product of concerted evolution, mutation, or something in between?

The classical model of concerted evolution states that hundreds to thousands of ribosomal DNA (rDNA) units undergo homogenization, making the multiple copies of the individual units more uniform across the genome than would be expected given mutation frequencies and gene redundancy. While the universality of this over 50-year-old model has been confirmed in a range of organisms, advanced high throughput sequencing techniques have also revealed that rDNA homogenization in many organisms is partial and, in rare cases, even apparently failing. The potential underpinning processes leading to unexpected intragenomic variation have been discussed in a number of studies, but a comprehensive understanding remains to be determined. In this work, we summarize information on variation or polymorphisms in rDNAs across a wide range of taxa amongst animals, fungi, plants, and protists. We discuss the definition and description of concerted evolution and describe whether incomplete concerted evolution of rDNAs predominantly affects coding or non-coding regions of rDNA units and if it leads to the formation of pseudogenes or not. We also discuss the factors contributing to rDNA variation, such as interspecific hybridization, meiotic cycles, rDNA expression status, genome size, and the activity of effector genes involved in genetic recombination, epigenetic modifications, and DNA editing. Finally, we argue that a combination of approaches is needed to target genetic and epigenetic phenomena influencing incomplete concerted evolution, to give a comprehensive understanding of the evolution and functional consequences of intragenomic variation in rDNA.

Sidestepping Darwin: horizontal gene transfer from plants to insects

Horizontal transfer of genetic material (HT) is the passage of DNA between organisms by means other than reproduction. Increasing numbers of HT are reported in insects, with bacteria, fungi, plants, and insects acting as the main sources of these transfers. Here, we provide a detailed account of plant-to-insect HT events. At least 14 insect species belonging to 6 orders are known to have received plant genetic material through HT. One of them, the whitefly Bemisia tabaci (Middle East Asia Minor 1), concentrates most of these transfers, with no less than 28 HT events yielding 55 plant-derived genes in this species. Several plant-to-insect HT events reported so far involve gene families known to play a role in plant-parasite interactions. We highlight methodological approaches that may further help characterize these transfers. We argue that plant-to-insect HT is likely more frequent than currently appreciated and that in-depth studies of these transfers will shed new light on plant-insect interactions.