The Role of Viral Infection in Inducing Variability in Virus-Free Progeny in Tomato

The effect of virus-host interactions on subsequent generations is poorly understood. The evaluation of the effects of viral infection on inheritance of quantitative traits in the progeny of infected plants and elucidation of a possible relationship between chiasma frequency in the infected plants and variability of traits in the progeny were investigated. The current study involved genotypes of four intraspecific hybrids of tomato （Solanum lycopersicum L.）, their parental forms and two additional cultivars. Used as infection were the tobacco mosaic virus （TMV） and potato virus X （PVX）. The consequences of the effect of viral infection were evaluated based on chromosome pairing in diakinesis and/or by examining quantitative and qualitative traits in the progeny of the infected tomato plants. Tomato plants infected with TMV ＋ PVX were found to differ in chiasma frequency per pollen mother cell or per bivalent. Deviations have been observed for genotypes of both F1 hybrids and cultivars. At the same time, differences in mean values of the traits under study have only been found for progeny populations （F2-F4） derived from virus-infected F1 hybrids, but not in the case of progeny of the infected cultivars. The rate of recombinants combining traits of both parents increased significantly （2.22-8.24 times） in progeny populations of hybrids infected with TMV＋PVX. The above suggests that the observed effects could be the result of modification of recombination frequencies that can be manifested in heterozygous hybrids and make small contributions to variability in cases of ＇homozygous＇ tomato genotypes （i.e. cultivars）.     

Exploring the Factor Structure of Neurocognitive Measures in Older Individuals

Here we focus on factor analysis from a best practices point of view, by investigating the factor structure of neuropsychological tests and using the results obtained to illustrate on choosing a reasonable solution. The sample (n=1051 individuals) was randomly divided into two groups: one for exploratory factor analysis (EFA) and principal component analysis (PCA), to investigate the number of factors underlying the neurocognitive variables; the second to test the “best fit” model via confirmatory factor analysis (CFA). For the exploratory step, three extraction (maximum likelihood, principal axis factoring and principal components) and two rotation (orthogonal and oblique) methods were used. The analysis methodology allowed exploring how different cognitive/psychological tests correlated/discriminated between dimensions, indicating that to capture latent structures in similar sample sizes and measures, with approximately normal data distribution, reflective models with oblimin rotation might prove the most adequate.     

A robust two-way semi-linear model for normalization of cDNA microarray data

Background  

Normalization is a basic step in microarray data analysis. A proper normalization procedure ensures that the intensity ratios provide meaningful measures of relative expression values.     

Salt Tolerant and Sensitive Rice Varieties Display Differential Methylome Flexibility under Salt Stress

DNA methylation has been referred as an important player in plant genomic responses to environmental stresses but correlations between the methylome plasticity and specific traits of interest are still far from being understood. In this study, we inspected global DNA methylation levels in salt tolerant and sensitive rice varieties upon salt stress imposition. Global DNA methylation was quantified using the 5-methylcytosine (5mC) antibody and an ELISA-based technique, which is an affordable and quite pioneer assay in plants, and in situ imaging of methylation sites in interphase nuclei of tissue sections. Variations of global DNA methylation levels in response to salt stress were tissue- and genotype-dependent. We show a connection between a higher ability of DNA methylation adjustment levels and salt stress tolerance. The salt-tolerant rice variety Pokkali was remarkable in its ability to quickly relax DNA methylation in response to salt stress. In spite of the same tendency for reduction of global methylation under salinity, in the salt-sensitive rice variety IR29 such reduction was not statistically supported. In ‘Pokkali’, the salt stress-induced demethylation may be linked to active demethylation due to increased expression of DNA demethylases under salt stress. In ‘IR29’, the induction of both DNA demethylases and methyltransferases may explain the lower plasticity of DNA methylation. We further show that mutations for epigenetic regulators affected specific phenotypic parameters related to salinity tolerance, such as the root length and biomass. This work emphasizes the role of differential methylome flexibility between salt tolerant and salt sensitive rice varieties as an important player in salt stress tolerance, reinforcing the need to better understand the connection between epigenetic networks and plant responses to environmental stresses.     

Myosin thick filaments from adult rabbit skeletal muscles

Myosin subfragment 1 (S1) forms dimers in the presence of Mg(2+) or MgADP or MgATP. The entire myosin molecule forms head-head dimers in the presence of MgATP. The angle between the two subunits in the S1 dimer is 95 degrees. Assuming that the length of the globular part of S1 is approximately 12 nm and that the S1/S2 joint (lever arm approximately 7 nm) is clearly bent, the cylinder tangent to this dimer should have a diameter of approximately 18 nm, close to the approximately 16-20 nm suggested by many studies for the diameter of thick filaments in situ. These conclusions led us to re-examine our previous model, according to which two heads from two opposite myosin molecules are inserted into the filament core and interact as dimers. We studied synthetic filaments by electron microscopy, enzyme activity assays, controlled digestion and filament-filament interaction analysis. Synthetic filaments formed by rapid dilution in the presence of 1 mM EDTA at room temperature ( approximately 22 degrees C) had all their myosin heads outside the backbone. These filaments are called superfilaments (SF). Synthetic filaments formed by slow dilution, in the presence of either 2 mM Mg(2+) or 0.5 mM MgATP and at low temperature ( approximately 0 degrees C) had one myosin head outside the backbone and one head inside. These filaments are called filaments (F). Synthetic filaments formed by slow dilution, in the presence of 4 mM MgATP at low temperature ( approximately 0 degrees C) had most of their heads inserted in the filament core. These filaments are called antifilaments (AF). These experimental results provide important new information about myosin synthetic filaments. In particular, we found that myosin heads were involved in filament assembly and that filament-filament interactions can occur via the external heads. Native filaments (NF) from rabbit psoas muscle were also studied by enzyme assays. Their structure depended on the age of the rabbit. NF from 4-month-old rabbits were three-stranded, i.e. six myosin heads per crown, two of which were inside the core and four outside. NF from 18-month-old rabbits were two-stranded (similar to F).     

Effect of abscisic acid on the photosynthetic oxygen evolution in barley chloroplasts

In vivo effect of abscisic acid (ABA) on photosynthetic oxygen evolution was investigated in barley chloroplasts. The most important kinetic parameters of O₂-producing reactions were changed. The results show inhibition of the O₂-flash yields at ABA concentrations of 10 mol/l and 100 mol/l and an increase in the degree of damping of the oscillations. ABA has a marked effect on the distribution of the oxygenevolving centers in S₀ and S₁ states and on sum of the centers (S₀+S₁) estimated according to the Kok model. In addition, the amplitude and the shape of the initial oxygen burst under continuous illumination are also significantly altered. At a concentration of 100 mol/l, ABA strongly inhibits Hill reaction activity measured by DCPIP reduction. The results cannot be explained by the hypothesis of socalled stomata effect. On the other hand, no effects were observed on the investigated parameters in experiments involving ABA applied in vitro to isolated chloroplasts. It is hypothesized that ABA disrupts the granal chloroplasts structure and raises the degree of participation of the cooperative mechanism of O₂-evolution connected with the functioning of PS II centers in the stroma situated thylakoids.Abbreviations DCPIP 2,6-Dichlorophenolindophenol - DCMU 3-(3,4-dichlorophenil)-1,1-dimethylurea - HEPES N-2-Hydroxyethylpiperazine-N-2-ethane sulfonic acid - PSII photosystem II - RubisCO Ribulose-1,5-bis-phosphate carboxylase-oxygenase     

Impaired attribution of emotion to facial expressions in anxiety and major depression

Background

Recognition of others'' emotions is an important aspect of interpersonal communication. In major depression, a significant emotion recognition impairment has been reported. It remains unclear whether the ability to recognize emotion from facial expressions is also impaired in anxiety disorders. There is a need to review and integrate the published literature on emotional expression recognition in anxiety disorders and major depression.

Methodology/Principal Findings

A detailed literature search was used to identify studies on explicit emotion recognition in patients with anxiety disorders and major depression compared to healthy participants. Eighteen studies provided sufficient information to be included. The differences on emotion recognition impairment between patients and controls (Cohen''s d) with corresponding confidence intervals were computed for each study. Over all studies, adults with anxiety disorders had a significant impairment in emotion recognition (d = −0.35). In children with anxiety disorders no significant impairment of emotion recognition was found (d = −0.03). Major depression was associated with an even larger impairment in recognition of facial expressions of emotion (d = −0.58).

Conclusions/Significance

Results from the current analysis support the hypothesis that adults with anxiety disorders or major depression both have a deficit in recognizing facial expression of emotions, and that this deficit is more pronounced in major depression than in anxiety.     

Positive crosstalk between ERK and p38 in melanoma stimulates migration and in vivo proliferation

Melanoma is one of the most therapy-resistant cancers. Activating mutations in BRAF and NRAS are the source of extracellular signal regulated protein kinase (ERK) pathway activation. We show that melanoma cell lines, originating in different metastatic sites, with BRAF or NRAS mutations, in addition to active mitogen activated protein kinase (MAPK)-ERK, also have highly activated stress activated protein kinase (SAPK)-p38. This is in direct contrast to carcinoma cells in which the activity of the two kinases appears to be mutually exclusive; high level of p38 activity inhibits, through a negative feedback, ERK activity and prevents tumorigenesis. Melanomas are insensitive to ERK inhibition by p38 and utilize p38-signaling pathway for migration and growth in vivo. We found a positive functional loop linking the high ERK activity to surface expression of alphaVbeta3-integrin. This integrin, by interacting with vitronectin, induces p38 activity and increases IL-8 production, enhancing cell migration. Because the negative loop from p38 to ERK is lost, the two kinases can remain simultaneously activated. Inhibition of ERK and p38 activities is more effective in blocking in vivo growth than inhibition of each kinase individually. Future therapies might have to consider targeting of both pathways.