The Inhibition of Nucleoside Transport in Human Erythrocytes by Mioflazine Analogues

Abstract

Kinetic analysis of the transport protein (both influx and efflux), usually performed with radiolabelled nucleosides such as adenosine and uridine, has provided a wealth of information regarding the various kinetic and equilibrium parameters (1).     

Comparative Genomics Elucidates the Origin of a Supergene Controlling Floral Heteromorphism

Supergenes are nonrecombining genomic regions ensuring the coinheritance of multiple, coadapted genes. Despite the importance of supergenes in adaptation, little is known on how they originate. A classic example of supergene is the S locus controlling heterostyly, a floral heteromorphism occurring in 28 angiosperm families. In Primula, heterostyly is characterized by the cooccurrence of two complementary, self-incompatible floral morphs and is controlled by five genes clustered in the hemizygous, ca. 300-kb S locus. Here, we present the first chromosome-scale genome assembly of any heterostylous species, that of Primula veris (cowslip). By leveraging the high contiguity of the P. veris assembly and comparative genomic analyses, we demonstrated that the S-locus evolved via multiple, asynchronous gene duplications and independent gene translocations. Furthermore, we discovered a new whole-genome duplication in Ericales that is specific to the Primula lineage. We also propose a mechanism for the origin of S-locus hemizygosity via nonhomologous recombination involving the newly discovered two pairs of CFB genes flanking the S locus. Finally, we detected only weak signatures of degeneration in the S locus, as predicted for hemizygous supergenes. The present study provides a useful resource for future research addressing key questions on the evolution of supergenes in general and the S locus in particular: How do supergenes arise? What is the role of genome architecture in the evolution of complex adaptations? Is the molecular architecture of heterostyly supergenes across angiosperms similar to that of Primula?     

Toward almost closed genomes with GapFiller

De novo assembly is a commonly used application of next-generation sequencing experiments. The ultimate goal is to puzzle millions of reads into one complete genome, although draft assemblies usually result in a number of gapped scaffold sequences. In this paper we propose an automated strategy, called GapFiller, to reliably close gaps within scaffolds using paired reads. The method shows good results on both bacterial and eukaryotic datasets, allowing only few errors. As a consequence, the amount of additional wetlab work needed to close a genome is drastically reduced. The software is available at http://www.baseclear.com/bioinformatics-tools/.     

Germination and pH of intracellular compartments in seeds of Phacelia tanacetifolia

³¹ P nuclear magnetic resonance spectroscope (NMR) was used to study the response of Phacelia tanacetifolia seeds to dark and light conditions during the first 72 h of incubation. Changes in the chemical shifts (δ) of the pH-dependent ³¹P-NMR signals from the vacuolar and the cytoplasmic orthophosphate pools were correlated with the different incubation conditions. In the dark (favorable to germination), the cytoplasmic pH remained nearly constant over the whole period considered, while the vacuolar pH shitted to more acidic values after the 24th h of incubation. In the light (inhibiting germination), the values of cytoplasmic pH tended to become more acidic than in the dark after the 24th h of incubation, while the vacuolar pH remained practically constant. When seed germination was inhibited in the dark by butyric acid (BA). a permeant weak acid, the values of cytoplasmic and vacuolar pH were similar to those of the ungerminated seeds incubated in the light. When, vice versa, seed germination was promoted in the light by fusicoccin (FC), the values of cytoplasmic and vacuolar pH were similar to those of the dark-germinated seeds. A progressive augmentation of P, metabolism occurred both in the dark and in the light up to the 24th h of incubation. Subsequently, light blocked any further evolution of this parameter. Treatment with butyric acid in the dark again mimicked the effect of light, while FC reversed the negative effect of light. The data show that in Phacelia tanacetifolia seeds germination is linked to a more alkaline cytoplasmic pH. The finding that the light-dependent metabolic inhibition occurs after an early activation of metabolism, i.e. after the first 24 h. suggests that the effects of light on the cytoplasmic and vacuolar pH depend on the early metabolic processes involved in the control of the homeostasis of cell pH and/or on the inhibition of the reactivation of the transport mechanisms.     

T-cell receptor gene rearrangements and expression in normal human large granular lymphocytes (LGL) and their pathological expansions

The lineage to which normal large granular lymphocytes/natural killer (LGL/NK) cells belong is controversial; in fact they share some surface markers and functional activities with monocytes, but also with T lymphocytes. The relationship of LGL to the T cell lineage by analysis with the T cell receptor (T-rec) gene has been investigated. Pure preparations of human LGL and their CD11⁺ CD8^- and CD11^- CD8⁺ subsets had the T gene in its unrearranged germline configuration. Expression of T and T genes was not detectable. The organization of T gene, which is of particular importance because it occurs early in T cell ontogeny, was also found in its germline configuration.A rare type of lymphoproliferative disorder, termed T-LPD, is characterized by expansion of cells very similar to LGL for morphology, phenotype, and functional activity. Of 17 patients with T-LPD studied for T-rec rearrangement, 15 displayed rearrangement of T and T loci and were CD3+ (14/15 had monoclonal rearrangement), while 2 cases were in germline configuration and were CD3–. Similarly to very small subsets of CD3+ LGL recently described, most T-LPD cases are CD3+ and have T-rec genes rearranged. These data suggest that either a subset of LGL or a particular step of differentiation may be related to the T cell lineage; they also demonstrate that, in contrast to previous views, most TLPD are monoclonal, presumably neoplastic, lymphoproliferative disorders.Abbreviations LGL large granular lymphocytes - NK natural killer - T-rec T-cell receptor - TLPD T lymphoproliferative disease