Stokes' Drift of linear Defects

A linear defect, viz. an elastic string, diffusing on a planar substrate traversed by a travelling wave experiences a drag known as Stokes' drift. In the limit of an infinitely long string, such a mechanism is shown to be characterized by a sharp threshold that depends on the wave parameters, the string damping constant and the substrate temperature. Moreover, the onset of the Stokes' drift is signaled by an excess diffusion of the string center of mass, while the dispersion of the drifting string around its center of mass may grow anomalous.Comment: 14 pages, no figures, to be published in Phys.Rev.

Arthrobacter sp. Inoculation Improves Cactus Pear Growth, Quality of Fruits, and Nutraceutical Properties of Cladodes

A study was undertaken to determine the effects of a strain of Arthrobacter sp., a Plant Growth-Promoting Bacteria (PGPB), on plant phenology and qualitative composition of Opuntia ficus-indica (L.) Mill. fruits and cladodes. The strain was inoculated in soil, and its effects on cactus pear plants were detected and compared to nontreated plants. Compared to the latter, the treatment with bacteria promoted an earlier plant sprouting (2 months before the control) and fruitification, ameliorating fruit quality (i.e., improved fresh and dry weight: + 24% and + 26%, respectively, increased total solid content by 30% and polyphenols concentrations by 22%). The quality and quantity of monosaccharides of cladodes were also increased by Arthrobacter sp. with a positive effect on their nutraceutical value. In summer, the mean values of xylose, arabinose, and mannose were significantly higher in treated compared to not treated plants (+ 3.54; + 7.04; + 4.76 mg/kg d.w. respectively). A similar trend was observed in autumn, when the cladodes of inoculated plants had higher contents, i.e., 33% xylose, 65% arabinose, and 40% mannose, respect to the controls. In conclusion, Arthrobacter sp. plays a role in the improvement of nutritional and nutraceutical properties of cactus pear plants due to its capabilities to promote plant growth. Therefore, these results open new perspectives in PGPB application in the agro-farming system as alternative strategy to improve cactus pear growth, yield, and cladodes quality, being the latter the main by-product to be utilized for additional industrial uses

Polyamine oxidase is involved in spermidine reduction of transglutaminase type 2-catalyzed βh-crystallins polymerization in calcium-induced experimental cataract

In an in vitro Ca2+-induced cataract model, the progression of opacification is paralleled by a rapid decrease of the endogenous levels of spermidine (SPD) and an increase of transglutaminase type 2 (TG2, EC 2.3.2.13)-catalyzed lens crystallins cross-linking by protein-boundN(1)-N-8-bis(gamma-glutamyl) SPD. This pattern was reversed adding exogenous SPD to the incubation resulting in a delayed loss of transparency of the rabbit lens. The present report shows evidence on the main incorporation of SPD by the catalytic activity of TG2, toward beta H-crystallins and in particular to the beta B2- and mostly in beta B3-crystallins. The increase of endogenous SPD in the cultured rabbit lens showed the activation of a flavin adenine dinucleotide (FAD)-dependent polyamine oxidases (PAO EC 1.5.3.11). As it is known that FAD-PAO degrades theN(8)-terminal reactive portion ofN(1)-mono(gamma-glutamyl) SPD, the protein-boundN(8)-mono(gamma-glutamyl) SPD was found the mainly available derivative for the potential formation of beta B3-crystallins cross-links by protein-boundN(1)-N-8-bis(gamma-glutamyl)SPD. In conclusion, FAD-PAO degradation of theN(8)-terminal reactive residue of the crystallins boundN(1)-mono(gamma-glutamyl)SPD together with the increased concentration of exogenous SPD, leading to saturation of glutamine residues on the substrate proteins, drastically reducesN(1)-N-8-bis(gamma-glutamyl)SPD crosslinks formation, preventing crystallins polymerization and avoiding rabbit lens opacification. The ability of SPD and MDL 72527 to modulate the activities of TG2 and FAD-PAO involved in the mechanism of lens opacification suggests a potential strategy for the prevention of senile cataract

A transcription factor network specifying inhibitory versus excitatory neurons in the dorsal spinal cord

The proper balance of excitatory and inhibitory neurons is crucial for normal processing of somatosensory information in the dorsal spinal cord. Two neural basic helix-loop-helix transcription factors (TFs), Ascl1 and Ptf1a, have contrasting functions in specifying these neurons. To understand how Ascl1 and Ptf1a function in this process, we identified their direct transcriptional targets genome-wide in the embryonic mouse neural tube using ChIP-Seq and RNA-Seq. We show that Ascl1 and Ptf1a directly regulate distinct homeodomain TFs that specify excitatory or inhibitory neuronal fates. In addition, Ascl1 directly regulates genes with roles in several steps of the neurogenic program, including Notch signaling, neuronal differentiation, axon guidance and synapse formation. By contrast, Ptf1a directly regulates genes encoding components of the neurotransmitter machinery in inhibitory neurons, and other later aspects of neural development distinct from those regulated by Ascl1. Moreover, Ptf1a represses the excitatory neuronal fate by directly repressing several targets of Ascl1. Ascl1 and Ptf1a bind sequences primarily enriched for a specific E-Box motif (CAGCTG) and for secondary motifs used by Sox, Rfx, Pou and homeodomain factors. Ptf1a also binds sequences uniquely enriched in the CAGATG E-box and in the binding motif for its co-factor Rbpj, providing two factors that influence the specificity of Ptf1a binding. The direct transcriptional targets identified for Ascl1 and Ptf1a provide a molecular understanding of how these DNA-binding proteins function in neuronal development, particularly as key regulators of homeodomain TFs required for neuronal subtype specification.National Institutes of Health grants: ([F31NS705592, R01 HD037932, R01 NS032817, F31 NS06144

The Single-Particle Spectral Function of 16O^{16}{\rm O}

The influence of short-range correlations on the $p$-wave single-particle spectral function in $^{16}{\rm O}$ is studied as a function of energy. This influence, which is represented by the admixture of high-momentum components, is found to be small in the $p$-shell quasihole wave functions. It is therefore unlikely that studies of quasihole momentum distributions using the $(e,e'p)$ reaction will reveal a significant contribution of high momentum components. Instead, high-momentum components become increasingly more dominant at higher excitation energy. The above observations are consistent with the energy distribution of high-momentum components in nuclear matter.Comment: 5 pages, RevTeX, 3 figure

Maternal exposure to di(2-ethylhexyl)phthalate (DEHP) promotes the transgenerational inheritance of adult-onset reproductive dysfunctions through the female germline in mice

Endocrine disruptors (EDS) are compounds known to promote transgenerational inheritance of adult-onset disease in subsequent generations after maternal exposure during fetal gonadal development. This study was designed to establish whether gestational and lactational exposure to the plasticizer di(2-ethylhexyl)phthalate (DEHP) at environmental doses promotes transgenerational effects on reproductive health in female offspring, as adults, over three generations in the mouse. Gestating F0 mouse dams were exposed to 0, 0.05, 5 mg/kg/day DEHP in the diet from gestational day 0.5 until the end of lactation. The incidence of adult-onset disease in reproductive function was recorded in F1, F2 and F3 female offspring. In adult Fl females, DEHP exposure induced reproductive adverse effects with: i) altered ovarian follicular dynamics with reduced primordial follicular reserve and a larger growing pre-antral follicle population, suggesting accelerated follicular recruitment; ii) reduced oocyte quality and embryonic developmental competence; iii) dysregulation of the expression profile of a panel of selected ovarian and pre-implantation embryonic genes. F2 and F3 female offspring displayed the same altered reproductive morphological phenotype and gene expression profiles as Fl, thus showing transgenerational transmission of reproductive adverse effects along the female lineage. These findings indicate that in mice exposure to DEHP at doses relevant to human exposure during gonadal sex determination significantly perturbs the reproductive indices of female adult offspring and subsequent generations. Evidence of transgenerational transmission has important implications for the reproductive health and fertility of animals and humans, significantly increasing the potential biohazards of this toxicant

Enhancement of Brassica napus Tolerance to High Saline Conditions by Seed Priming.

Plants grown in saline soils undergo osmotic and oxidative stresses, affecting growth and photosynthesis and, consequently, the yield. Therefore, the increase in soil salinity is a major threat to crop productivity worldwide. Plant’s tolerance can be ameliorated by applying simple methods that induce them to adopt morphological and physiological adjustments to counteract stress. In this work, we evaluated the effects of seed priming on salt stress response in three cultivars of rapeseed (Brassica napus L.) that had different tolerance levels. Seed chemical priming was performed with 2.5 mM spermine (SPM), 5 mM spermidine (SPD), 40 mM NaCl and 2.5 mM Ca (NO3 )2 . Primed and not primed seeds were sown on saline and not saline (controls) media, and morphological and physiological parameters were determined. Since SPD treatment was effective in reducing salinity negative effects on growth, membrane integrity and photosynthetic pigments, we selected this priming to further investigate plant salt stress response. The positive effects of this seed treatment on growth and physiological responses were evident when primed plants were compared to not primed ones, grown under the same saline conditions. SPD priming ameliorated the tolerance towards saline stress, in a genotype-independent manner, by increasing photosynthetic pigments, proline amounts and antioxidant responses in all cultivars exposed to salt. These results may open new perspectives for crop productivity in the struggle against soil salinization

Flavonoids: a myth or a reality for cancer therapy?

Nutraceuticals are biologically active molecules present in foods; they can have beneficial effects on health, but they are not available in large enough quantities to perform this function. Plant metabolites, such as polyphenols, are widely diffused in the plant kingdom, where they play fundamental roles in plant development and interactions with the environment. Among these, flavonoids are of particular interest as they have significant effects on human health. In vitro and/or in vivo studies described flavonoids as essential nutrients for preventing several diseases. They display broad and promising bioactivities to fight cancer, inflammation, bacterial infections, as well as to reduce the severity of neurodegenerative and cardiovascular diseases or diabetes. Therefore, it is not surprising that interest in flavonoids has sharply increased in recent years. More than 23,000 scientific publications on flavonoids have described the potential anticancer activity of these natural molecules in the last decade. Studies, in vitro and in vivo, show that flavonoids exhibit anticancer properties, and many epidemiological studies confirm that dietary intake of flavonoids leads to a reduced risk of cancer. This review provides a glimpse of the mechanisms of action of flavonoids on cancer cells

PGPB Improve Photosynthetic Activity and Tolerance to Oxidative Stress in Brassica napus Grown on Salinized Soils.

Soil salinization, one of the most common causes of soil degradation, negatively affects plant growth, reproduction, and yield in plants. Saline conditions elicit some physiological changes to cope with the imposed osmotic and oxidative stresses. Inoculation of plants with some bacterial species that stimulate their growth, i.e., plant growth-promoting bacteria (PGPB), may help plants to counteract saline stress, thus improving the plant’s fitness. This manuscript reports the effects of the inoculation of a salt-sensitive cultivar of Brassica napus (canola) with five different PGPB species (separately), i.e., Azospirillum brasilense, Arthrobacter globiformis, Burkholderia ambifaria, Herbaspirillum seropedicae, and Pseudomonas sp. on plant salt stress physiological responses. The seeds were sown in saline soil (8 dS/m) and inoculated with bacterial suspensions. Seedlings were grown to the phenological stage of rosetta, when morphological and physiological features were determined. In the presence of the above-mentioned PGPB, salt exposed canola plants grew better than noninoculated controls. The water loss was reduced in inoculated plants under saline conditions, due to a low level of membrane damage and the enhanced synthesis of the osmolyte proline, the latter depending on the bacterial strain inoculated. The reduction in membrane damage was also due to the increased antioxidant activity (i.e., higher amount of phenolic compounds, enhanced superoxide dismutase, and ascorbate peroxidase activities) in salt-stressed and inoculated Brassica napus. Furthermore, the salt-stressed and inoculated plants did not show detrimental effects to their photosynthetic apparatus, i.e., higher efficiency of PSII and low energy dissipation by heat for photosynthesis were detected. The improvement of the response to salt stress provided by PGPB paves the way to further use of PGPB as inoculants of plants grown in saline soils