Regeneration of leaf mesophyll protoplasts of tomato cultivars (L. esculentum): factors important for efficient protoplast culture and plant regeneration

Conditions were established for efficient plant regeneration from four freshmarket cultivars of Lycopersicon esculentum. In order to increase the yield of viable protoplasts which are able to sustain cell divisions, the donor plants are preconditioned by incubation at 25°C in the dark for 18 hours, followed by a cold treatment at 4°C in the dark for the last 6 hours, prior to protoplast isolation. Browning of the dividing cell colonies can be prevented by culturing protoplasts in 100 l droplets of low-melting agarose, surrounded by liquid medium. Alternatively, protoplasts can be cultured in liquid medium. In both procedures the plating efficiencies and percentage of shoot regeneration are increased, only when dilutions were performed with auxin-free culture medium. Shoot regeneration is obtained by using a two step procedure: initiation of greening of microcalli on a medium containing 0.2 M mannitol and 7.3 mM sucrose, which is followed by shoot development on a mannitol-free medium containing 0.5 M sucrose. In this way, plants can be regenerated within 3 months from the hybrid cultivars Bellina, Abunda, Sonatine and also from the true seedline Moneymaker. The latter one showed the highest regeneration frequency (30%).Abbreviations BAP 6-Benzylamino purine - 2,4-D 2,4-dichlorophenoxy acetic acid - IAA indole acetic acid - MES 2-(N-morpholino)- ethane sulfonic acid - NAA naphthalene acetic acid - PE plating efficiency     

A general synthetic method toward uridylylated picornavirus VPg proteins

Small proteins called viral protein genome‐linked (VPg), attached to the 5′‐end of the viral RNA genome are found as common structure in the large family of picornaviruses. The replication of these viruses is primed by this VPg protein linked to a single uridylyl residue. We report a general procedure to obtain such nucleoproteins employing a pre‐uridylylated tyrosine building block in an on‐line solid phase‐based approach. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.     

Sex Differences in Mathematics and Reading Achievement Are Inversely Related: Within- and Across-Nation Assessment of 10 Years of PISA Data

We analyzed one decade of data collected by the Programme for International Student Assessment (PISA), including the mathematics and reading performance of nearly 1.5 million 15 year olds in 75 countries. Across nations, boys scored higher than girls in mathematics, but lower than girls in reading. The sex difference in reading was three times as large as in mathematics. There was considerable variation in the extent of the sex differences between nations. There are countries without a sex difference in mathematics performance, and in some countries girls scored higher than boys. Boys scored lower in reading in all nations in all four PISA assessments (2000, 2003, 2006, 2009). Contrary to several previous studies, we found no evidence that the sex differences were related to nations’ gender equality indicators. Further, paradoxically, sex differences in mathematics were consistently and strongly inversely correlated with sex differences in reading: Countries with a smaller sex difference in mathematics had a larger sex difference in reading and vice versa. We demonstrate that this was not merely a between-nation, but also a within-nation effect. This effect is related to relative changes in these sex differences across the performance continuum: We did not find a sex difference in mathematics among the lowest performing students, but this is where the sex difference in reading was largest. In contrast, the sex difference in mathematics was largest among the higher performing students, and this is where the sex difference in reading was smallest. The implication is that if policy makers decide that changes in these sex differences are desired, different approaches will be needed to achieve this for reading and mathematics. Interventions that focus on high-achieving girls in mathematics and on low achieving boys in reading are likely to yield the strongest educational benefits.     

Aberrant Levels of Hematopoietic/Neuronal Growth and Differentiation Factors in Euthyroid Women at Risk for Autoimmune Thyroid Disease

BackgroundSubjects at risk for major mood disorders have a higher risk to develop autoimmune thyroid disease (AITD) and vice-versa, implying a shared pathogenesis. In mood disorder patients, an abnormal profile of hematopoietic/neuronal growth factors is observed, suggesting that growth/differentiation abnormalities of these cell lineages may predispose to mood disorders. The first objective of our study was to investigate whether an aberrant profile of these hematopoietic/neuronal growth factors is also detectable in subjects at risk for AITD. A second objective was to study the inter relationship of these factors with previously determined and published growth factors/cytokines in the same subjects.MethodsWe studied 64 TPO-Ab-negative females with at least 1 first- or second-degree relative with AITD, 32 of whom did and 32 who did not seroconvert to TPO-Ab positivity in 5-year follow-up. Subjects were compared with 32 healthy controls (HCs). We measured serum levels of brain-derived neurotrophic factor (BDNF), Stem Cell Factor (SCF), Insulin-like Growth Factor-Binding Protein 2 (IGFBP-2), Epidermal Growth Factor (EGF) and IL-7 at baseline.ResultsBDNF was significantly lower (8.2 vs 18.9 ng/ml, P<0.001), while EGF (506.9 vs 307.6 pg/ml, P = 0.003) and IGFBP-2 (388.3 vs 188.5 ng/ml, P = 0.028) were significantly higher in relatives than in HCs. Relatives who seroconverted in the next 5 years had significantly higher levels of SCF than non-seroconverters (26.5 vs 16.7 pg/ml, P = 0.017). In a cluster analysis with the previously published growth factors/cytokines SCF clustered together with IL-1β, IL-6 and CCL-3, of which high levels also preceded seroconversion.ConclusionRelatives of AITD patients show aberrant serum levels of 4 hematopoietic/neuronal growth factors similar to the aberrancies found in mood disorder patients, suggesting that shared growth and differentiation defects in both the hematopoietic and neuronal system may underlie thyroid autoimmunity and mood disorders. A distinct pattern of four inter correlating immune factors in the relatives preceded TPO-Ab seroconversion in the next 5 years.     

Empty class II major histocompatibility complex created by peptide photolysis establishes the role of DM in peptide association

DM catalyzes the exchange of peptides bound to Class II major histocompatibility complex (MHC) molecules. Because the dissociation and association components of the overall reaction are difficult to separate, a detailed mechanism of DM catalysis has long resisted elucidation. UV irradiation of DR molecules loaded with a photocleavable peptide (caged Class II MHC molecules) enabled synchronous and verifiable evacuation of the peptide-binding groove and tracking of early binding events in real time by fluorescence polarization. Empty DR molecules generated by photocleavage rapidly bound peptide but quickly resolved into species with substantially slower binding kinetics. DM formed a complex with empty DR molecules that bound peptide with even faster kinetics than empty DR molecules just having lost their peptide cargo. Mathematical models demonstrate that the peptide association rate of DR molecules is substantially higher in the presence of DM. We therefore unequivocally establish that DM contributes directly to peptide association through formation of a peptide-loading complex between DM and empty Class II MHC. This complex rapidly acquires a peptide analogous to the MHC class I peptide-loading complex.     

Comparing mortality in renal patients on hemodialysis versus peritoneal dialysis using a marginal structural model

When comparing the causal effect of peritoneal dialysis (PD) and hemodialysis (HD) treatment on lowering mortality in renal patients, using observational data, it is necessary to adjust for different forms of confounding and informative censoring. Both the type of dialysis treatment that is started with and mortality are affected by baseline covariates. Longitudinal and baseline variables can affect both the probability of switching from one type of dialysis to the other, and mortality. Longitudinal and baseline variables can also affect the probability of receiving a kidney transplant, possibly causing informative censoring. Adjusting for longitudinal variables by including them as covariates in a regression model potentially causes bias, for instance by losing a possible indirect effect of dialysis on mortality via these longitudinal variables. Instead, we fitted a marginal structural model (MSM) to estimate the causal effect of dialysis type, adjusted for confounding and informative censoring. We used the MSM to compare the hazard of death as well as cumulative survival between the potential treatment trajectories "always PD" and "always HD" over time, conditional on age and diabetes mellitus status. We used inverse probability weighting (IPW) to fit the MSM.     

Synthesis and evaluation of strand and turn modified ring-extended gramicidin S derivatives

In this paper, we describe the crystal structure of previously reported ring-extended gramicidin S (GS) derivative 2 (GS14K4), containing a d-amino acid residue in one of the β-strand regions. This structure is in agreement with a previously reported modeling study of the same molecule. The polar side chain of the additional d-amino acid residue is positioned at the same face of the molecule as the hydrophobic side chains, and we believe that because of this compound 2 is considerably less hydrophobic than extended GS derivatives in which the strand regions are exclusively composed of l-amino acids. Using this backbone structure as our benchmark we prepared a small series of ring-extended GS analogues featuring sugar amino acid dipeptide isosteres of varied hydrophobicity at the turn region. We show that via this approach hydrophobicity of extended GS analogues can be tuned without affecting the secondary structure (as observed from NMR and CD spectra). Biological evaluation reveals that hydrophobicity correlates to cell toxicity, but still bacteriolysis is induced with GS analogues that are too hydrophilic to efficiently lyse human red blood cells.     

Sex differences in search and gathering skills

The hunter–gatherer theory of sex differences states that female cognition has evolutionarily adapted to gathering and male cognition to hunting. Existing studies corroborate that men excel in hunting-related skills, but there is only indirect support for women excelling in gathering tasks. This study tested if women would outperform men in laboratory-based computer tests of search and gathering skills. In Experiment 1, men found target objects faster and made fewer mistakes than women in a classic visual search study. In Experiment 2, participants gathered items (fruits or letters presented on screen), and again, men performed significantly better. In Experiment 3, participants' incidental learning of object locations in a search experiment was studied, but no statistically significant sex differences were observed. These findings found the opposite of what was expected based on the hypothesis that female cognition has adapted to gathering. Alternative interpretations of the role of object location memory, female gathering roles and the division of labor between the sexes are discussed.     

A phase-II study of pegylated interferon alfa-2b for patients with metastatic renal cell carcinoma and removal of the primary tumor

Twenty-two patients with metastatic renal cell carcinoma and removal of the primary tumor were treated with subcutaneous pegylated interferon alfa-2b (PEG-Intron) to evaluate toxicity and efficacy. Start dose was 3.0 g/kg/week, escalated to 6.0 g/kg/week. After 2 months, therapy was extended in case of response or stable disease (SD) until progressive disease (PD) or relapse for a maximum of 2 years. National Cancer Institute common toxicity criteria (NCI-CTC) were monitored every 2–4 weeks. After 2 months, nine patients did not continue (8 PD, 1 SD with grade 4 CTC) and 13 extended treatment [three partial response (PR), 10 SD], of these, 11 progressed. One patient with PR developed a durable complete response later. Overall response rate was 13.6% (3/22). Median overall survival is 13 months (range 3–35 months). Dosage was escalated to 6 g/kg/week in three patients . NCI-CTC grade 2 and 3 required dose attenuation in 12 patients during escalation, and reduction in 10 during the trial. Three patients discontinued because of grade 4 CTC (two fatigue, one hyperglycemia). Fatigue was the major dose-limiting toxicity. These results suggest an efficacy and toxicity of PEG-Intron comparable to standard interferon alfa-2b in patients with mRCC and removal of the primary tumor.Author disclosure declaration: None of the authors has a relationship with pharmaceutical companies, biomedical device manufacturers or other corporations whose products or services are related to the subject matter of the submission, nor do the authors have financial interests such as investments, licensing, or other commercial interest in any drugs, goods, or services in connection with the matter under consideration.     

Characteristics of bovine early puerperal uterine contractility recorded under farm conditions

A non-invasive, digital technique was used to measure and quantify intrauterine pressure (IUP) changes in early postpartum dairy cows kept under farm conditions in order to document physiological changes in uterine contractility after uncomplicated calvings. In addition, possible relationships between characteristics of uterine contractility and blood ionized calcium (Ca(2+))-concentrations were investigated. Recordings of uterine contractility were made by using a transcervically inserted open tip catheter in 12 healthy cows during their first 48h after calving. The IUP recording technique appeared easily applicable under farm conditions. Although mean frequency (FREQ), amplitude (AMP) and area under the curve (AUC) of the myometrial contractions significantly decreased due to time, untreated early postpartum cows showed a high variability in characteristics of uterine contractility. There was no correlation between blood Ca2+ -concentrations and any of the contractility parameters.