Analysis of the association between CD40 and CD40 ligand polymorphisms and systemic sclerosis

Introduction

The aim of the present study was to investigate the possible role of CD40 and CD40 ligand (CD40LG) genes in the susceptibility and phenotype expression of systemic sclerosis (SSc).

Methods

In total, 2,670 SSc patients and 3,245 healthy individuals from four European populations (Spain, Germany, The Netherlands, and Italy) were included in the study. Five single-nucleotide polymorphisms (SNPs) of CD40 (rs1883832, rs4810485, rs1535045) and CD40LG (rs3092952, rs3092920) were genotyped by using a predesigned TaqMan allele-discrimination assay technology. Meta-analysis was assessed to determine whether an association exists between the genetic variants and SSc or its main clinical subtypes.

Results

No evidence of association between CD40 and CD40LG genes variants and susceptibility to SSc was observed. Similarly, no significant statistical differences were observed when SSc patients were stratified by the clinical subtypes, the serologic features, and pulmonary fibrosis.

Conclusions

Our results do not suggest an important role of CD40 and CD40LG gene polymorphisms in the susceptibility to or clinical expression of SSc.     

ABA inhibits embryo cell expansion and early cell division events during coffee (Coffea arabica 'Rubi') seed germination

Background and Aims

Coffee seed germination represents an interplay between the embryo and the surrounding endosperm. A sequence of events in both parts of the seed determines whether germination will be successful or not. Following previous studies, the aim here was to further characterize the morphology of endosperm degradation and embryo growth with respect to morphology and cell cycle, and the influence of abscisic acid on these processes.

Methods

Growth of cells in a fixed region of the axis was quantified from light micrographs. Cell cycle events were measured by flow cytometry and by immunocytochemistry, using antibodies against β-tubulin. Aspects of the endosperm were visualized by light and scanning electron microscopy.

Key Results

The embryonic axis cells grew initially by isodiametric expansion. This event coincided with reorientation and increase in abundance of microtubules and with accumulation of β-tubulin. Radicle protrusion was characterized by a shift from isodiametric expansion to elongation of radicle cells and further accumulation of β-tubulin. Early cell division events started prior to radicle protrusion. Abscisic acid decreased the abundance of microtubules and inhibited the growth of the embryo cells, the reorganization of the microtubules, DNA replication in the embryonic axis, the formation of a protuberance and the completion of germination. The endosperm cap cells had smaller and thinner cell walls than the rest of the endosperm. Cells in the endosperm cap displayed compression followed by loss of cell integrity and the appearance of a protuberance prior to radicle protrusion.

Conclusions

Coffee seed germination is the result of isodiametric growth of the embryo followed by elongation, at the expense of integrity of endosperm cap cells. The cell cycle, including cell division, is initiated prior to radicle protrusion. ABA inhibits expansion of the embryo, and hence subsequent events, including germination.Key words: Abscisic acid, β-tubulin, Coffea arabica, coffee seed, cell morphology, germination, microtubules     

Pilot-scale conversion of lime-treated wheat straw into bioethanol: quality assessment of bioethanol and valorization of side streams by anaerobic digestion and combustion

Introduction  

The limited availability of fossil fuel sources, worldwide rising energy demands and anticipated climate changes attributed to an increase of greenhouse gasses are important driving forces for finding alternative energy sources. One approach to meeting the increasing energy demands and reduction of greenhouse gas emissions is by large-scale substitution of petrochemically derived transport fuels by the use of carbon dioxide-neutral biofuels, such as ethanol derived from lignocellulosic material.     

Metabolomic analysis of tomato seed germination

Introduction

Seed germination is inherently related to seed metabolism, which changes throughout its maturation, desiccation and germination processes. The metabolite content of a seed and its ability to germinate are determined by underlying genetic architecture and environmental effects during development.

Objective

This study aimed to assess an integrative approach to explore genetics modulating seed metabolism in different developmental stages and the link between seed metabolic- and germination traits.

Methods

We have utilized gas chromatography-time-of-flight/mass spectrometry (GC-TOF/MS) metabolite profiling to characterize tomato seeds during dry and imbibed stages. We describe, for the first time in tomato, the use of a so-called generalized genetical genomics (GGG) model to study the interaction between genetics, environment and seed metabolism using 100 tomato recombinant inbred lines (RILs) derived from a cross between Solanum lycopersicum and Solanum pimpinellifolium.

Results

QTLs were found for over two-thirds of the metabolites within several QTL hotspots. The transition from dry to 6 h imbibed seeds was associated with programmed metabolic switches. Significant correlations varied among individual metabolites and the obtained clusters were significantly enriched for metabolites involved in specific biochemical pathways.

Conclusions

Extensive genetic variation in metabolite abundance was uncovered. Numerous identified genetic regions that coordinate groups of metabolites were detected and these will contain plausible candidate genes. The combined analysis of germination phenotypes and metabolite profiles provides a strong indication for the hypothesis that metabolic composition is related to germination phenotypes and thus to seed performance.

     

Dispersal towards food: the singular limit of an Allen–Cahn equation

Journal of Mathematical Biology - The effect of dispersal under heterogeneous environment is studied in terms of the singular limit of an Allen–Cahn equation. Since biological organisms often...     

Mature B cells are required for acute splenic infection, but not for establishment of latency, by murine gammaherpesvirus 68.

Murine gammaherpesvirus 68 (gamma HV-68; also referred to as MHV-68) is a gammaherpesvirus which infects murid rodents. Previous studies showed that CD8 T cells are important for controlling gamma HV-68 replication during the first 2 weeks of infection and suggested a role for B cells in latent or persistent gamma HV-68 infection. To further define the importance of B cells and CD8 T cells during acute and chronic gamma HV-68 infection, we examined splenic infection in mice with null mutations in the transmembrane domain of the mu-heavy-chain constant region (MuMT; B-cell and antibody deficient) or in the beta2-microglobulin gene (beta2 -/-; CD8 deficient). Immunocompetent mice infected intraperitoneally with gamma HV-68 demonstrated peak splenic titers 9 to 10 days postinfection, cleared infectious virus 15 to 20 days postinfection, and harbored low levels of latent virus at 6 weeks postinfection. Beta2-/- mice showed peak splenic gamma HV-68 titers similar to those of normal mice but were unable to clear infectious virus completely from the spleen, demonstrating persistent infectious virus 6 weeks postinfection. These data indicate that CD8 T cells are important for clearing infectious gamma HV-68 from the spleen. Infected MuMT mice did not demonstrate detectable infectious gamma HV-68 in the spleen at any time after infection, indicating that mature B lymphocytes are necessary for acute splenic infection by gamma HV-68. Despite the lack of measurable acute infection, MuMT spleen cells harbored latent virus 6 weeks postinfection at a level about 100-fold higher than that in normal mice. These data demonstrate establishment of latency by a herpesvirus in an organ in the absence of acute viral replication in that organ. In addition, they demonstrate that gamma HV-68 can establish latency in a cell type other than mature B lymphocytes.     

Endo-β-mannanase isoforms are present in the endosperm and embryo of tomato seeds, but are not essentially linked to the completion of germination

A current hypothesis is that endo--mannanase activity in the endosperm cap of tomato (Lycopersicon esculentum Mill. cv. Moneymaker) seeds is induced by gibberellin (GA) and weakens the endosperm cap thus permitting radicle protrusion. We have tested this hypothesis. In isolated parts, the expression of endo--mannanase in the endosperm after germination is induced by GAs, but the expression of endo--mannanase in the endosperm cap prior to radicle protrusion is not induced by GAs. Also, abscisic acid (ABA) is incapable of inhibiting endo--mannanase activity in the endosperm cap, even though it strongly inhibits germination. However, ABA does inhibit enzyme activity in the endosperm and embryo after germination. There are several isoforms in the endosperm cap and embryo prior to radicle protrusion that are tissue-specific. Tissue prints showed that enzyme activity in the embryo spreads from the radicle tip to the cotyledons with time after the start of imbibition. The isoform and developmental patterns of enzyme activity on tissueprints are unaffected when seeds are incubated in ABA, even though germination is inhibited. We conclude that the presence of endo--mannanase activity in the endosperm cap is not in itself sufficient to permit tomato seeds to complete germination.Abbreviations ABA cis/trans-abscisic acid - GA(s) gibberellin(s) - IEF isoelectric focussing - pI(s) isoelectric point(s) We thank Dr. Bruce Downie for the seemingly endless but inspiring discussions.     

Protein transfer from an aqueous phase into reversed micelles. The effect of protein size and charge distribution

Proteins are spontaneously transferred from an aqueous solution into reversed micelles, provided the aqueous phase has the proper composition. Besides the composition of the aqueous phase, the composition of the organic phase and the properties of the proteins also play a role. We studied uptake profiles of 19 proteins as a function of pH of the aqueous solution. The organic phase consisted of trioctylmethylammonium chloride and nonylphenol pentaethoxylate (Rewopal HV5) as surfactant, octanol as cosurfactant and isooctane as continuous phase. In all cases, except for rubredoxin, proteins were transferred at pH values above their isoelectric point. The pH where maximal solubilization takes place can be described by the relationship: pHoptimum = isoelectric point +0.11 x 10(-3) Mr -0.97. So, the larger the protein, the more charge is needed to provide the energy required for the adaptation of the micellar size to the protein size. For protein transfer into sodium di-(2-ethylhexyl)sulphosuccinate (AOT) reversed micelles a similar relationship was found. The percentage of protein transferred could be related to the symmetry of charge distribution over the protein. This symmetry was expressed as the % of random electric moments on a protein that is larger than the effective electric moment of the protein (% S) [Barlow, D. J. and Thornton, J. M. (1986) Biopolymers 25, 1717]. The larger the value of % S, the more homogeneously the charges are distributed and the lower the percentage transfer.     

Seed dormancy and germination: the role of abscisic acid and gibberellins and the importance of hormone mutants

Over the past decades many studies have aimed at elucidating the regulation of seed dormancy and germination. Many hypotheses have been proposed and rejected but the regulatory principle behind changes in dormancy and induction of germination is still a black box. The majority of proposed mechanisms have a role for certain plant hormones in common. Abscisic acid and the gibberellins are the hormones most frequently suggested to control these processes. The development of hormone-deficient mutants made it possible to provide direct evidence for the involvement of hormones in germination and dormancy related processes.In the present paper an attempt is made to assess the role of abscisic acid and gibberellins in the transitions between dormant and non-dormant states and germination. First a conceptual framework is presented in which the different states of dormancy and germination are defined in order to contribute to a solution of the semantic confusion about these terms that has existed since the beginning of seed physiology.It is concluded that abscisic acid plays a pivotal role during the development of primary dormancy and gibberellins are involved in the induction of germination. Changes in sensitivity to these hormones occur during changes in dormancy. Both synthesis of and responsiveness to the hormones are controlled by natural environmental factors such as light, temperature and nitrate.