The first homosporous lycophyte genome revealed the association between the recent dynamic accumulation of LTR-RTs and genome size variation.

The contrasting genome size between homosporous and heterosporous plants is fascinating. Different from the heterosporous seed plants and mainly homosporous ferns, the lycophytes are either heterosporous (Isoetales and Selaginellales) or homosporous (Lycopodiales). Many lycophytes are the resource plants of Huperzine A (HupA) which is invaluable for treating Alzheimer's disease. For the seed-free vascular plants, several high-quality genomes of heterosporous Selaginella, homosporous ferns (maidenhair fern, monkey spider tree fern), and heterosporous ferns (Azolla) have been published and provided important insights into the origin and evolution of early land plants. However, the homosporous lycophyte genome has not been decoded. Here, we assembled the first homosporous lycophyte genome and conducted comparative genomic analyses by applying a reformed pipeline for filtering out non-plant sequences. The obtained genome size of Lycopodium clavatum is 2.30 Gb, distinguished in more than 85% repetitive elements of which 62% is long terminal repeat (LTR). This study disclosed a high birth rate and a low death rate of the LTR-RTs in homosporous lycophytes, but the opposite occurs in heterosporous lycophytes. we propose that the recent activity of LTR-RT is responsible for the immense genome size variation between homosporous and heterosporous lycophytes. By combing Ks analysis with a phylogenetic approach, we discovered two whole genome duplications (WGD). Morover, we identified all the five recognized key enzymes for the HupA biosynthetic pathway in the L. clavatum genome, but found this pathway incomplete in other major lineages of land plants. Overall, this study is of great importance for the medicinal utilization of lycophytes and the decoded genome data will be a key cornerstone to elucidate the evolution and biology of early vascular land plants.

Next-generation sequencing yields the complete chloroplast genome of Abies yuanbaoshanensis, an endangered species from South China.

Abies yuanbaoshanensis is critically endangered and restricted in the Yuanbao Mountain of China, with no more than 900 surviving individuals. Here, we reported the complete chloroplast (cp) genome of A. yuanbaoshanensis. The complete chloroplast genome is 121,795 bp in size. In total, 114 genes were identified, including 68 peptide-encoding genes, 35 tRNA genes, 4 rRNA genes, 6 open reading frames, and 1 pseudogene. Thirteen genes contain introns. In phylogenetic analysis, both the ML and BI analyses supported the monophyly of the genus Abies. Our study will provide potential genetic resources for further conservation and evolutionary studies of this highly endangered species.

Changes in liquid clearance of alveolar epithelium after oleic acid-induced acute lung injury in rats / 中华创伤杂志(英文版)

<p><b>OBJECTIVE</b>Impaired active fluid transport of alveolar epithelium may involve in the pathogenesis and resolution of alveolar edema. The objective of this study was to explore the changes in alveolar epithelial liquid clearance during lung edema following acute lung injury induced by oleic acid.</p><p><b>METHODS</b>Forty-eight Wistar rats were randomly divided into six groups, i.e., injured, amiloride, ouabain, amiloride plus ouabain and terbutaline groups. Twenty-four hours after the induction of acute lung injury by intravenous oleic acid (0.25 ml/kg), 5% albumin solution with 1.5 microCi (125)I-labeled albumin (5 ml/kg) was delivered into both lungs via trachea. Alveolar liquid clearance (ALC), extravascular lung water (EVLW) content and arterial blood gases were measured one hour thereafter.</p><p><b>RESULTS</b>At 24 h after the infusion of oleic acid, the rats developed pulmonary edema and severe hypoxemia, with EVLW increased by 47.9% and ALC decreased by 49.2%. Addition of either 2x10(-3) M amiloride or 5x10(-4) M ouabain to the instillation further reduced ALC and increased EVLW. ALC increased by approximately 63.7% and EVLW decreased by 46.9% with improved hypoxemia in the Terbutaline (10(-4) M) group, compared those in injured rats. A significant negative correlation was found between the increment of EVLW and the reduction of ALC.</p><p><b>CONCLUSIONS</b>Active fluid transport of alveolar epithelium might play a role in the pathogenesis of lung edema in acute lung injury.</p>