Functional phylogeny relates LET-756 to fibroblast growth factor 9

Fibroblast growth factors (FGFs) are secreted regulatory proteins involved in various developmental processes. In vertebrates, the FGF superfamily comprises 22 members. In non-vertebrates, six FGF genes have been identified in Ciona intestinalis, three in Drosophila melanogaster, and two (let-756 and egl-17) in Caenorhabditis elegans. The core of LET-756 shares a 30-50% sequence identity with the various members of the superfamily. The relationships between vertebrate and non-vertebrate FGFs are not clear. We made chimeric FGFs by replacing the core region of LET-756 by the cores of various mammalian, fly, and worm FGFs. LET-756 deleted in its core region was no longer able to rescue the lethal phenotype of a let-756 null mutant, and only chimeras containing the cores of FGFs 9, 16, and 20 showed rescue capacity. This core contains an internal motif of six amino acid residues (EFISIA) whose deletion or mutation abolished both the rescue activity and FGF secretion in the supernatant of transfected COS-1 cells. Chimera containing the core of C. intestinalis FGF9/16/20, a potential ortholog of FGF9 lacking the complete EFISIA motif, was not able to rescue the lethal phenotype or be secreted. However, the introduction of the EFISIA motif restored both activities. The data show that the EFISIA motif in the core of LET-756 is essential for its biological activity and that FGFs 9, 16, and 20, which contain that motif, are functionally close to LET-756 and may be evolutionary related. This non-classical mode of secretion using an internal motif is conserved throughout evolution.     

Plasma membrane depolarization induced by abscisic acid in Arabidopsis suspension cells involves reduction of proton pumping in addition to anion channel activation, which are both Ca2+ dependent

In Arabidopsis suspension cells a rapid plasma membrane depolarization is triggered by abscisic acid (ABA). Activation of anion channels was shown to be a component leading to this ABA-induced plasma membrane depolarization. Using experiments employing combined voltage clamping, continuous measurement of extracellular pH, we examined whether plasma membrane H(+)-ATPases could also be involved in the depolarization. We found that ABA causes simultaneously cell depolarization and medium alkalinization, the second effect being abolished when ABA is added in the presence of H+ pump inhibitors. Inhibition of the proton pump by ABA is thus a second component leading to the plasma membrane depolarization. The ABA-induced depolarization is therefore the result of two different processes: activation of anion channels and inhibition of H(+)-ATPases. These two processes are independent because impairing one did not suppress the depolarization. Both processes are however dependent on the [Ca2+]cyt increase induced by ABA since increase in [Ca(2+)](cyt) enhanced anion channels and impaired H(+)-ATPases.     

Dystrophin deficiency markedly increases enterovirus-induced cardiomyopathy: a genetic predisposition to viral heart disease

Both enteroviral infection of the heart and mutations in the dystrophin gene can cause cardiomyopathy. Little is known, however, about the interaction between genetic and acquired forms of cardiomyopathy. We previously demonstrated that the enteroviral protease 2A cleaves dystrophin; therefore, we hypothesized that dystrophin deficiency would predispose to enterovirus-induced cardiomyopathy. We observed more severe cardiomyopathy, worsening over time, and greater viral replication in dystrophin-deficient mice infected with enterovirus than in infected wild-type mice. This difference appears to be a result of more efficient release of the virus from dystrophin-deficient myocytes. In addition, we found that expression of wild-type dystrophin in cultured cells decreased the cytopathic effect of enteroviral infection and the release of virus from the cell. We also found that expression of a cleavage-resistant mutant dystrophin further inhibited the virally mediated cytopathic effect and viral release. These results indicate that viral infection can influence the severity and penetrance of the cardiomyopathy that occurs in the hearts of dystrophin-deficient individuals.     

Species delimitation of the liquorice tribe (Leguminosae: Glycyrrhizeae) based on phylogenomic and machine learning analyses

The liquorice tribe Glycyrrhizeae is a leguminous herbaceous group of plants comprised of the genera Glycyrrhiza and Glycyrrhizopsis. Some Glycyrrhiza taxa contain glycyrrhizin, a pharmacologically significant sweet substance that also has applications in crafting industrial materials. Here, we utilized an expanded taxon sampling of Glycyrrhizeae to reconstruct the phylogenetic relationships in the tribe based on genome skimming data, including whole chloroplast genomes, nuclear ribosomal DNA, and low-copy nuclear DNA. We also launched machine learning analysis (MLA) for one species pair with controversial taxonomic boundary. The integrated results indicated Glycyrrhizopsis should be split from Glycyrrhiza, while the former genus Meristotropis should be treated as part of Glycyrrhiza. Glycyrrhizopsis includes two species, Glycyrrhizopsis asymmetrica and Glycyrrhizopsis flavescens, and we recognize 13 species in Glycyrrhiza: Glycyrrhiza acanthocarpa, Glycyrrhiza astragalina, Glycyrrhiza bucharica, Glycyrrhiza echinata, Glycyrrhiza foetida, Glycyrrhiza glabra, Glycyrrhiza gontscharovii, Glycyrrhiza lepidota, Glycyrrhiza macedonica, Glycyrrhiza pallidiflora, Glycyrrhiza squamulosa, Glycyrrhiza triphylla, and Glycyrrhiza yunnanensis. We propose a broader G. glabra that includes former Glycyrrhiza aspera, G. glabra s.s., Glycyrrhiza inflata, and Glycyrrhiza uralensis, and represents the glycyrrhizin-contained medicinal group. Our ancestral state inferences show the ancestor of Glycyrrhiza lacked glycyrrhizin, and the presence of glycyrrhizin evolved twice within Glycyrrhiza during the last one million years. Our integrative phylogenomics-MLA study not only provides new insights into long-standing taxonomic controversies of Glycyrrhizeae, but also represents a useful approach for future taxonomic studies on other plant taxa.     

Rearrangements of integral membrane components during in vitro aging of sheep erythrocyte membranes

In vitro aged sheep erythrocytes and sheep erythrocyte ghosts spontaneously release vesicles that consist of long protrusions affixed to flattened headlike structures. The intramembranous particles seen on the protoplasmic face of freeze fracture electron micrographs of vesicle protrusions are arranged in paired particle rows. On the equivalent fracture face of headlike structures, the particle density is low; if particles are present, they are clustered along the rim of the flattened headlike structure and at the junction with the protrusion. The released vesicles are depleted of the intramembranous particles seen on the exoplasmic face of ghost but retain almost exclusively particles of the protoplasmic face. Correspondingly, the exoplasmic face of ghosts that have released vesicles reveals a 28 percent higher density of intramembranous particles than that of fresh ghosts. Purified vesicles are depleted of spectrin but retain integral membrane proteins, with one of an apparent mol wt of 160,000 accounting for nearly 50 percent of the total protein (Lutz, H.U.,R. Barber, and R.F. McGuire. 1976. J. Biol. Chem. 251:3500-3510). When vesicles are modified with the cleavable cross-linking reagent [(35)S]dithiobis (succinimidyl propionate)at 0 degrees C, the 160,000 mol wt protein is rapidly converted to disulfide-linked dimers and higher oligomers. Exposure of intact ghosts to the reagent in the same way fails to yield equivalent polymers. A comparison of the morphological and biochemical aspects of ghosts and vesicles suggest that a marked rearrangement of membrane proteins accompanies the supramolecular redistribution of intramembranous particles during spontaneous vesiculation. The results also suggest that the paired particles of the protoplasmic face of vesicle protrusions are arranged in paired helices and contain the 160,000 mol wt protein as dimers.     

Targeting residual inflammatory risk in coronary disease: to catch a monkey by its tail

Patients with coronary disease remain at high risk for future cardiovascular events, even with optimal risk factor modification, lipid-lowering drugs and antithrombotic regimens. A myriad of inflammatory pathways contribute to progression of the atherosclerotic burden in these patients. Only in the last few years has the inflammatory biology of atherosclerosis translated into clinical therapeutic options. Low-dose colchicine can provide a clinically relevant reduction in the risk for composite and individual major cardiovascular outcomes in patients with acute and chronic coronary syndromes. Among others, its anti-inflammatory effects in atherosclerosis seem to be related to neutrophil recruitment and adhesion, inflammasome inhibition, and morphological changes in platelets and platelet aggregation. Future research is aimed at further elucidating its particular mechanism of action, as well as identifying patients with the highest expected benefit and evaluating efficacy in other vascular beds. These data will help to formulate the role of colchicine and other anti-inflammatory drugs in patients with coronary disease and atherosclerosis in general in the near future.     

Mosaic: a position-effect variegation eye-color mutant in the mosquito Anopheles gambiae

The Mosaic (Mos) mutation, isolated in the F1 of 60Co-irradiated mosquitoes, confers variegated eye color to third and fourth instar larvae, pupae, and adults of the mosquito Anopheles gambiae. Mos is recessive in wild pink eye (p+) individuals, but is dominant and confers areas of wild-type pigment in mutant pink eye backgrounds. Mos is located 14.4 cM from pink eye on the X chromosome and is associated with a duplication of division 2B euchromatin that has been inserted into division 6 heterochromatin. Various combinations of Mos, pink eye alleles, and the autosomal mutation red eye were produced. In all cases, the darker pigmented regions of the eye in Mos individuals show the phenotypic interactions expected if the phenotype of those regions is due to expression of a p+ allele. Expression of Mos is suppressed by rearing larvae at 32 degrees C relative to 22 degrees C. All of these characteristics are consistent with Mos being a duplicated wild copy of the pink eye gene undergoing position-effect variegation.     

Herpes simplex virus 1 envelopment follows two diverse pathways

Herpesvirus envelopment is assumed to follow an uneconomical pathway including primary envelopment at the inner nuclear membrane, de-envelopment at the outer nuclear membrane, and reenvelopment at the trans-Golgi network. In contrast to the hypothesis of de-envelopment by fusion of the primary envelope with the outer nuclear membrane, virions were demonstrated to be transported from the perinuclear space to rough endoplasmic reticulum (RER) cisternae. Here we show by high-resolution microscopy that herpes simplex virus 1 envelopment follows two diverse pathways. First, nuclear envelopment includes budding of capsids at the inner nuclear membrane into the perinuclear space whereby tegument and a thick electron dense envelope are acquired. The substance responsible for the dense envelope is speculated to enable intraluminal transportation of virions via RER into Golgi cisternae. Within Golgi cisternae, virions are packaged into transport vacuoles containing one or several virions. Second, for cytoplasmic envelopment, capsids gain direct access from the nucleus to the cytoplasm via impaired nuclear pores. Cytoplasmic capsids could bud at the outer nuclear membrane, at membranes of RER, Golgi cisternae, and large vacuoles, and at banana-shaped membranous entities that were found to continue into Golgi membranes. Envelopes originating by budding at the outer nuclear membrane and RER membrane also acquire a dense substance. Budding at Golgi stacks, designated wrapping, results in single virions within small vacuoles that contain electron-dense substances between envelope and vacuolar membranes.