Some effects of chromium toxicity on bush bean plants grown in soil

Summary Chromium applied to a noncalcareous soil at 50 ppm did not decrease yields of bush beans (Phaseolus vulgaris L. var Improved Tendergreen), but when EDTA (ethylenediamine tetraacetic acid) was added with it, it did. Very little Cr was present in leaves. In solution culture 10^-5 M Cr and higher were toxic. With solution culture the highest level of Cr in leaves was about 30 ppm and in general there was a decreasing gradient in Cr from roots to stems to leaves. EDTA had less effect in solution cultures on Cr toxicity because the Cr was already in solution. Chromium toxicity decreased cation levels in plants.     

A combined LDL receptor/LDL receptor adaptor protein 1 mutation as the cause for severe familial hypercholesterolemia

Familial hypercholesterolemia (FH) results from impaired catabolism of plasma low density lipoproteins (LDL), thus leading to high cholesterol, atherosclerosis, and a high risk of premature myocardial infarction. FH is commonly caused by defects of the LDL receptor or its main ligand apoB, together mediating cellular uptake and clearance of plasma LDL. In some cases FH is inherited by mutations in the genes of PCSK9 and LDLRAP1 (ARH) in a dominant or recessive trait. The encoded proteins are required for LDL receptor stability and internalization within the LDLR pathway. To detect the underlying genetic defect in a family of Turkish descent showing unregular inheritance of severe FH, we screened the four candidate genes by denaturing gradient gel electrophoresis (DGGE) mutation analysis. We identified different combinatory mixtures of LDLR- and LDLRAP1-gene defects as the cause for severe familial hypercholesterolemia in this family. We also show for the first time that a heterozygous LDLR mutation combined with a homozygous LDLRAP1 mutation produces a more severe hypercholesterolemia phenotype in the same family than a homozygous LDLR mutation alone.     

Magnetoelectric nanocomposite scaffold for high yield differentiation of mesenchymal stem cells to neural-like cells

While the differentiation factors have been widely used to differentiate mesenchymal stem cells (MSCs) into various cell types, they can cause harm at the same time. Therefore, it is beneficial to propose methods to differentiate MSCs without factors. Herein, magnetoelectric (ME) nanofibers were synthesized as the scaffold for the growth of MSCs and their differentiation into neural cells without factors. This nanocomposite takes the advantage of the synergies of the magnetostrictive filler, CoFe₂O ₄ nanoparticles (CFO), and piezoelectric polymer, polyvinylidene difluoride (PVDF). Graphene oxide nanosheets were decorated with CFO nanoparticles for a proper dispersion in the polymer through a hydrothermal process. After that, the piezoelectric PVDF polymer, which contained the magnetic nanoparticles, underwent the electrospun process to form ME nanofibers, the ME property of which has the potential to be used in areas such as tissue engineering, biosensors, and actuators.     

Natural variation in decision-making behavior in Drosophila melanogaster

There has been considerable recent interest in using Drosophila melanogaster to investigate the molecular basis of decision-making behavior. Deciding where to place eggs is likely one of the most important decisions for a female fly, as eggs are vulnerable and larvae have limited motility. Here, we show that many natural genotypes of D. melanogaster prefer to lay eggs near nutritious substrate, rather than in nutritious substrate. These preferences are highly polymorphic in both degree and direction, with considerable heritability (0.488) and evolvability.Relative preferences are modulated by the distance between options and the overall concentration of ethanol, suggesting Drosophila integrate many environmental factors when making oviposition decisions. As oviposition-related decisions can be efficiently assessed by simply counting eggs, oviposition behavior is an excellent model for understanding information processing in insects. Associating natural genetic polymorphisms with decision-making variation will shed light on the molecular basis of host choice behavior, the evolutionary maintenance of genetic variation, and the mechanistic nature of preference variation in general.     

The influence of gibberellic acid and sulfur fertilization rate on growth and S-use efficiency of mustard (<Emphasis Type="Italic">Brassica juncea</Emphasis>)

Earlier research has shown that exogenous gibberellic acid (GA₃) application increases shoot growth, photosynthesis and soil nitrogen (N) utilisation in mustard (Brassica juncea L. Czern & Coss.). Mustard has a high sulfur (S) requirement. Its assimilatory pathway is well coordinated with N and dependent on photosynthesis. Thus, the higher photosynthate production and an efficient use of N with the use of GA₃ could result in an increase in S-use efficiency of the crop. The research was, therefore, carried out to study the effects of 10~M GA₃ spray on specific leaf area, plant dry mass, leaf carbon dioxide exchange rate (CER), plant growth rate (PGR), relative growth rate (RGR), net assimilation rate (NAR) and S-use efficiency (SUE) of mustard treated with 0, 100 or 200 mg S kg^–1 soil levels. Plants treated with 100~mg S kg^–1 soil and receiving GA₃ treatment showed increased specific leaf area and dry mass accumulation compared to the control. At 0~mg S kg^–1 soil, N and S concentrations were reduced. They increased with increasing S supply. GA₃ application significantly increased N and S concentrations further. A two-fold increase in SUE in GA₃-treated plants at 100~mg S kg^–1 soil was noted in comparison to the control. SUE was not increased under excess S conditions beyond 100~mg S kg^–1 soil. The increase in SUE was through increase in the growth, CER and use efficiency of N by the crop due to GA₃ application.     

Ultrafine carbon particles induce apoptosis and proliferation in rat lung epithelial cells via specific signaling pathways both using EGF-R

Apoptosis and proliferation are important causes of adverse health effects induced by inhaled ultrafine particles. The molecular mechanisms of particle cell interactions mediating these end points are therefore a major topic of current particle toxicology and molecular preventive medicine. Initial studies revealed that ultrafine particles induce apoptosis and proliferation in parallel in rat lung epithelial cells, dependent on time and dosage. With these end points, two antagonistic reactions seem to be induced by the same extracellular stimulus. It was therefore investigated whether proliferation is induced directly by the particles or as a compensation of particle-caused cell death. Experimental conditions excluding compensatory proliferation demonstrated that both end points are induced independently by specific signaling pathways. Events eliciting signaling cascades leading to apoptosis and proliferation were studied with specific inhibitors of membrane receptors. Epidermal growth factor receptor (EGF-R) kinase activity was identified as essential for apoptosis as well as for proliferation. As ultrafine particle-induced proliferation alone was dependent on the activation of beta1-integrins, these membrane receptors are suggested to mediate the specificity of EGF-R signaling concerning the decision as to whether apoptosis or proliferation is triggered. Accordingly, MAP kinase signaling downstream of EGF-R showed comparable specificity with regard to receptor-dependent induction of apoptosis and proliferation. As key mediators of signaling cascades, the activation of extracellular signal-regulated kinases 1 and 2 proved to be specific for proliferation in a beta1-integrin-dependent manner, whereas phosphorylation of c-Jun NH2-terminal kinases 1 and 2 was correlated with the induction of apoptosis.     

Fenretinide prevents lipid-induced insulin resistance by blocking ceramide biosynthesis

Fenretinide is a synthetic retinoid that is being tested in clinical trials for the treatment of breast cancer and insulin resistance, but its mechanism of action has been elusive. Recent in vitro data indicate that fenretinide inhibits dihydroceramide desaturase, an enzyme involved in the biosynthesis of lipotoxic ceramides that antagonize insulin action. Because of this finding, we assessed whether fenretinide could improve insulin sensitivity and glucose homeostasis in vitro and in vivo by controlling ceramide production. The effect of fenretinide on insulin action and the cellular lipidome was assessed in a number of lipid-challenged models including cultured myotubes and isolated muscles strips incubated with exogenous fatty acids and mice fed a high-fat diet. Insulin action was evaluated in the various models by measuring glucose uptake or disposal and the activation of Akt/PKB, a serine/threonine kinase that is obligate for insulin-stimulated anabolism. The effects of fenretinide on cellular lipid levels were assessed by LC-MS/MS. Fenretinide negated lipid-induced insulin resistance in each of the model systems assayed. Simultaneously, the drug depleted cells of ceramide, while promoting the accumulation of the precursor dihydroceramide, a substrate for the reaction catalyzed by Des1. These data suggest that fenretinide improves insulin sensitivity, at least in part, by inhibiting Des1 and suggest that therapeutics targeting this enzyme may be a viable therapeutic means for normalizing glucose homeostasis in the overweight and diabetic.     

Identification and regulation of a molecular module for bleb-based cell motility

Single-cell migration is a key process in development, homeostasis, and disease. Nevertheless, the control over basic cellular mechanisms directing cells into motile behavior in?vivo is largely unknown. Here, we report on the identification of a minimal set of parameters the regulation of which confers proper morphology and cell motility. Zebrafish primordial germ cells rendered immotile by knockdown of Dead end, a negative regulator of miRNA function, were used as a platform for identifying processes restoring motility. We have defined myosin contractility, cell adhesion, and cortex properties as factors whose proper regulation is sufficient for restoring cell migration of this cell type. Tight control over the level of these cellular features, achieved through a balance between miRNA-430 function and the action of the RNA-binding protein Dead end, effectively transforms immotile primordial germ cells into polarized cells that actively migrate relative to cells in their environment.     

Effect of short- and long-term strength exercise on cardiac oxidative stress and performance in rat

Increase in heart metabolism during severe exercise facilitates production of ROS and result in oxidative stress. Due to shortage of information, the effect of chronic strength exercise on oxidative stress and contractile function of the heart was assessed to explore the threshold for oxidative stress in this kind of exercise training. Male Wistar rats (80) were divided into two test groups exercised 1 and 3 months and two control groups without exercise. Strength exercise was carried by wearing a Canvas Jacket with weights and forced rats to lift the weights. Rats were exercised at 70% of maximum lifted weight 6 days/week, four times/day, and 12 repetitions each time. Finally, the hearts of ten rats/group were homogenized and MDA, SOD, GPX, and catalase (CAT) were determined by ELISA method. In other ten rats/group, left ventricle systolic and end diastolic pressures (LVSP and LVEDP) and contractility indices (LVDP and +dp/dt max) and relaxation velocity (−dp/dt max) were recorded. The coronary outflow was collected. Short- and long-term strength exercise increased heart weight and heart/BW ratio (P < 0.05). In the 3-month exercise group, basal heart rate decreased (P < 0.05). LVEDP did not change but LVDP, +dp/dt max, −dp/dt max, and coronary flow significantly increased in both exercise groups (P < 0.05). None of MDA or SOD, GPX, and CAT significantly changed. The results showed that sub-maximal chronic strength exercise improves heart efficiency without increase in oxidative stress index or decrease in antioxidant defense capacity. These imply that long-time strength exercise up to this intensity is safe for cardiac health.     

Photosynthetic Rate, Growth, and Yield of Mustard Plants Sprayed with 28-Homobrassinolide

Thirty-day-old plants of mustard (Brassica juncea L.) were sprayed with 10⁻¹⁰, 10⁻⁸, or 10⁻⁶ M aqueous solution of 28-homobrassinolide (HBR). The HBR-treated plants were healthier than those treated with water and yielded more. Maximum increase over control was found in 60-d-old, 10⁻⁸ M-HBR-treated plants in fresh and dry mass per plant, carbonic anhydrase (CA, E.C. 4.2.1.1) activity, and net photosynthetic rate (P _N), at harvest in number of pods per plant and seed yield per plant (the respective values were 25, 30, 34, 69, 24, and 29 %). A further increase in the concentration of HBR (10⁻⁶ M) did not make any additional impact on the growth and yield. Increased CA activity and P _N were correlated with growth and seed yield. This revised version was published online in August 2006 with corrections to the Cover Date.