Sterol binding by OSBP-related protein 1L regulates late endosome motility and function

ORP1L is an oxysterol binding homologue that regulates late endosome (LE) positioning. We show that ORP1L binds several oxysterols and cholesterol, and characterize a mutant, ORP1L Δ560–563, defective in oxysterol binding. While wild-type ORP1L clusters LE, ORP1L Δ560–563 induces LE scattering, which is reversed by disruption of the endoplasmic reticulum (ER) targeting FFAT motif, suggesting that it is due to enhanced LE–ER interactions. Endosome motility is reduced upon overexpression of ORP1L. Both wild-type ORP1L and the Δ560–563 mutant induce the recruitment of both dynactin and kinesin-2 on LE. Most of the LE decorated by overexpressed ORP1L fail to accept endocytosed dextran or EGF, and the transfected cells display defective degradation of internalized EGF. ORP1L silencing in macrophage foam cells enhances endosome motility and results in inhibition of [³H]cholesterol efflux to apolipoprotein A-I. These data demonstrate that LE motility and functions in both protein and lipid transport are regulated by ORP1L.     

Genome-wide association study identifies multiple loci influencing human serum metabolite levels

Nuclear magnetic resonance assays allow for measurement of a wide range of metabolic phenotypes. We report here the results of a GWAS on 8,330 Finnish individuals genotyped and imputed at 7.7 million SNPs for a range of 216 serum metabolic phenotypes assessed by NMR of serum samples. We identified significant associations (P < 2.31 × 10(-10)) at 31 loci, including 11 for which there have not been previous reports of associations to a metabolic trait or disorder. Analyses of Finnish twin pairs suggested that the metabolic measures reported here show higher heritability than comparable conventional metabolic phenotypes. In accordance with our expectations, SNPs at the 31 loci associated with individual metabolites account for a greater proportion of the genetic component of trait variance (up to 40%) than is typically observed for conventional serum metabolic phenotypes. The identification of such associations may provide substantial insight into cardiometabolic disorders.     

Effects of ingested phytoecdysteroids in the female soft tickOrnithodoros moubata

The effects of the ingestion of some phytoecdysteroids were studied in the soft tickOrnithodoros moubata. Supernumerary moulting and malformations of first leg pairs were obtained with 22-oxo-20-hydroxyecdysone, 20-hydroxyecdysone-22-acetate, and 20-hydroxyecdysone-22-benzoate. Egg-yield was reduced with 20-hydroxyecdysone-22-acetate and carthamosterone. Finally, drying-out of eggs was observed with carthamosterone and 22-deoxy-20,26-dihydroxyecdysone. In addition, we demonstrated that there is a correlation between the number of completed gonotrophic cycles and the impossibility of inducing supernumerary moulting.     

Perspectives on executive information systems

Executives who consider the acquisition of Executive Information Systems (EIS) may encounter several major problems already in their selection and introduction stages. Key issues are the following: Can the EIS's really match our managerial needs and support decision making in our organizational contingencies? How widely in the leadership levels can they be introduced? Are they easy-to-learn, easy-to-use and easily customizable? Do they utilize the newest information technology, e.g. graphics and modern interface technology? Can they work in our computer network? In order to facilitate elegant solutions of the selection problems, we construct an evaluation framework which guides the selection of an EIS product to match the managerial needs according to the organizational contingencies. This framework is useful immediately after the specification of the decision making support requirements of the executive. The effectiveness of the framework is shown by applying it and analyzing 13 EIS products. We also offer introduction and use experiences from four English and four Finnish large companies covering the opinions of 132 EIS users. In this paper we give general answers to the questions above and discuss other relevant issues.     

Ligand-dependent localization and function of ORP–VAP complexes at membrane contact sites

Oxysterol-binding protein/OSBP-related proteins (ORPs) constitute a conserved family of sterol/phospholipid-binding proteins with lipid transporter or sensor functions. We investigated the spatial occurrence and regulation of the interactions of human OSBP/ORPs or the S. cerevisiae orthologs, the Osh (OSBP homolog) proteins, with their endoplasmic reticulum (ER) anchors, the VAMP-associated proteins (VAPs), by employing bimolecular fluorescence complementation and pull-down set-ups. The ORP–VAP interactions localize frequently at distinct subcellular sites, shown in several cases to represent membrane contact sites (MCSs). Using established ORP ligand-binding domain mutants and pull-down assays with recombinant proteins, we show that ORP liganding regulates the ORP–VAP association, alters the subcellular targeting of ORP–VAP complexes, or modifies organelle morphology. There is distinct protein specificity in the effects of the mutants on subcellular targeting of ORP–VAP complexes. We provide evidence that complexes of human ORP2 and VAPs at ER–lipid droplet interfaces regulate the hydrolysis of triglycerides and lipid droplet turnover. The data suggest evolutionarily conserved, complex ligand-dependent functions of ORP–VAP complexes at MCSs, with implications for cellular lipid homeostasis and signaling.     

Sympatric speciation in palms on an oceanic island

The origin of species diversity has challenged biologists for over two centuries. Allopatric speciation, the divergence of species resulting from geographical isolation, is well documented. However, sympatric speciation, divergence without geographical isolation, is highly controversial. Claims of sympatric speciation must demonstrate species sympatry, sister relationships, reproductive isolation, and that an earlier allopatric phase is highly unlikely. Here we provide clear support for sympatric speciation in a case study of two species of palm (Arecaceae) on an oceanic island. A large dated phylogenetic tree shows that the two species of Howea, endemic to the remote Lord Howe Island, are sister taxa and diverged from each other well after the island was formed 6.9 million years ago. During fieldwork, we found a substantial disjunction in flowering time that is correlated with soil preference. In addition, a genome scan indicates that few genetic loci are more divergent between the two species than expected under neutrality, a finding consistent with models of sympatric speciation involving disruptive/divergent selection. This case study of sympatric speciation in plants provides an opportunity for refining theoretical models on the origin of species, and new impetus for exploring putative plant and animal examples on oceanic islands.     

Neuronal ceroid lipofuscinosis protein CLN3 interacts with motor proteins and modifies location of late endosomal compartments

CLN3 is an endosomal/lysosomal transmembrane protein mutated in classical juvenile onset neuronal ceroid lipofuscinosis, a fatal inherited neurodegenerative lysosomal storage disorder. The function of CLN3 in endosomal/lysosomal events has remained elusive due to poor understanding of its interactions in these compartments. It has previously been shown that the localisation of late endosomal/lysosomal compartments is disturbed in cells expressing the most common disease-associated CLN3 mutant, CLN3?ex7-8 (c.462-677del). We report here that a protracted disease causing mutant, CLN3E295K, affects the properties of late endocytic compartments, since over-expression of the CLN3E295K mutant protein in HeLa cells induced relocalisation of Rab7 and a perinuclear clustering of late endosomes/lysosomes. In addition to the previously reported disturbances in the endocytic pathway, we now show that the anterograde transport of late endosomal/lysosomal compartments is affected in CLN3 deficiency. CLN3 interacted with motor components driving both plus and minus end microtubular trafficking: tubulin, dynactin, dynein and kinesin-2. Most importantly, CLN3 was found to interact directly with active, guanosine-5'-triphosphate (GTP)-bound Rab7 and with the Rab7-interacting lysosomal protein (RILP) that anchors the dynein motor. The data presented in this study provide novel insights into the role of CLN3 in late endosomal/lysosomal membrane transport.     

The earliest angiosperms: evidence from mitochondrial, plastid and nuclear genomes

Angiosperms have dominated the Earth's vegetation since the mid-Cretaceous (90 million years ago), providing much of our food, fibre, medicine and timber, yet their origin and early evolution have remained enigmatic for over a century. One part of the enigma lies in the difficulty of identifying the earliest angiosperms; the other involves the uncertainty regarding the sister group of angiosperms among extant and fossil gymnosperms. Here we report a phylogenetic analysis of DNA sequences of five mitochondrial, plastid and nuclear genes (total aligned length 8,733 base pairs), from all basal angiosperm and gymnosperm lineages (105 species, 103 genera and 63 families). Our study demonstrates that Amborella, Nymphaeales and Illiciales-Trimeniaceae-Austrobaileya represent the first stage of angiosperm evolution, with Amborella being sister to all other angiosperms. We also show that Gnetales are related to the conifers and are not sister to the angiosperms, thus refuting the Anthophyte Hypothesis. These results have far-reaching implications for our understanding of diversification, adaptation, genome evolution and development of the angiosperms.