Inhibition of canonical Wnt signaling promotes gliogenesis in P0-NSCs

Wnt signaling plays an essential role in the development of mammalian central nervous system. We investigated the impact of activation/inhibition of the Wnt signaling pathway on neuronal/glial differentiation in neurospheres derived from neonatal mouse forebrains. For short term alterations, neurospheres were stimulated with recombinant Wnt-3a, Wnt-5a and the Wnt inhibitor Dickkopf-1 (Dkk1). Furthermore, neurospheres were transduced with retroviral vectors encoding Wnt-3a, Wnt-7a and their inhibitors Dkk1 and soluble Frizzled related protein-5 (sFRP5). Long-term activation of Wnt pathway by Wnt-7a or by treatment with GSK3 inhibitors promoted a moderate increase of the neuronal differentiation and blocked gliogenesis. In contrast, Wnt pathway inhibition in neurospheres, induced by retroviral overexpression of either Dkk1 or sFRP5, robustly increased the gliogenesis at the expense of neurogenesis. In summary, our data demonstrate that activation or inhibition of Wnt/β-catenin signaling in neurospheres regulates neuronal and glial differentiation, respectively. Thus, our results suggest that Wnt signaling may also contribute to regulate these processes in the neonatal brain.     

Land crabs as key drivers in tropical coastal forest recruitment

Plant populations are regulated by a diverse assortment of abiotic and biotic factors that influence seed dispersal and viability, and seedling establishment and growth at the microsite. Rarely does one animal guild exert as significant an influence on different plant assemblages as land crabs. We review three tropical coastal ecosystems–mangroves, island maritime forests, and mainland coastal terrestrial forests–where land crabs directly influence forest composition by limiting tree establishment and recruitment. Land crabs differentially prey on seeds, propagules and seedlings along nutrient, chemical and physical environmental gradients. In all of these ecosystems, but especially mangroves, abiotic gradients are well studied, strong and influence plant species distributions. However, we suggest that crab predation has primacy over many of these environmental factors by acting as the first limiting factor of tropical tree recruitment to drive the potential structural and compositional organisation of coastal forests. We show that the influence of crabs varies relative to tidal gradient, shoreline distance, canopy position, time, season, tree species and fruiting periodicity. Crabs also facilitate forest growth and development through such activities as excavation of burrows, creation of soil mounds, aeration of soils, removal of leaf litter into burrows and creation of carbon-rich soil microhabitats. For all three systems, land crabs influence the distribution, density and size-class structure of tree populations. Indeed, crabs are among the major drivers of tree recruitment in tropical coastal forest ecosystems, and their conservation should be included in management plans of these forests.     

PGC-1α Is a Key Regulator of Glucose-Induced Proliferation and Migration in Vascular Smooth Muscle Cells

Background

Atherosclerosis is a complex pathological condition caused by a number of mechanisms including the accelerated proliferation of vascular smooth muscle cells (VSMCs). Diabetes is likely to be an important risk factor for atherosclerosis, as hyperglycemia induces vascular smooth muscle cell (VSMC) proliferation and migration and may thus contribute to the formation of atherosclerotic lesions. This study was performed to investigate whether PGC-1α, a PPARγ coactivator and metabolic master regulator, plays a role in regulating VSMC proliferation and migration induced by high glucose.

Methodology/Principal Findings

PGC-1α mRNA levels are decreased in blood vessel media of STZ-treated diabetic rats. In cultured rat VSMCs, high glucose dose-dependently inhibits PGC-1α mRNA expression. Overexpression of PGC-1α either by infection with adenovirus, or by stimulation with palmitic acid, significantly reduces high glucose-induced VSMC proliferation and migration. In contrast, suppression of PGC-1α by siRNA mimics the effects of glucose on VSMCs. Finally, mechanistic studies suggest that PGC-1α-mediated inhibition of VSMC proliferation and migration is regulated through preventing ERK1/2 phosphorylation.

Conclusions/Significance

These results indicate that PGC-1α is a key regulator of high glucose-induced proliferation and migration in VSMCs, and suggest that elevation of PGC-1α in VSMC could be a useful strategy in preventing the development of diabetic atherosclerosis.     

Reversal of Small,Dense LDL Subclass Phenotype by Normalization of Adiposity

Excess adiposity and high‐carbohydrate diets have been associated with an atherogenic lipoprotein phenotype (ALP) characterized by increased concentrations of small, dense low‐density lipoprotein (LDL) particles (pattern B). We tested whether weight loss and normalization of adiposity could reverse ALP in overweight men with pattern B. After consuming a moderate‐carbohydrate, high‐fat diet for 3 weeks, pattern B and nonpattern B (pattern A) men were randomized to a weight loss (n = 60 and n = 36, respectively) or control weight‐stable arm (n = 20 and n = 17, respectively). Men in the weight loss arm consumed ～1,000 fewer calories per day over 9 weeks to induce an average ～9 kg weight loss. In the control group, weight stability was maintained for 4 weeks after randomization. Weight loss led to the conversion of pattern B to pattern A in 58% of baseline pattern B men. Among men who achieved BMIs of <25 kg/m² (62% of pattern B men vs. 83% of pattern A men), 81% of pattern B men converted to pattern A. Weight loss was associated with a significantly greater decrease in small, dense LDL subclass 3b in pattern B relative to pattern A men. The lipoprotein profiles of pattern A men who converted from pattern B were comparable to those of men with pattern A at baseline. Conversion of LDL subclass pattern B to pattern A and reversal of ALP can be achieved in a high proportion of overweight men by normalization of adiposity.     

Assembly of synthetic locked chromophores with agrobacterium phytochromes Agp1 and Agp2

Phytochromes are photoreceptors with a bilin chromophore in which light triggers the conversion between the red-absorbing form Pr and the far-red-absorbing form Pfr. Agrobacterium tumefaciens has two phytochromes, Agp1 and Agp2, with antagonistic properties: in darkness, Agp1 converts slowly from Pfr to Pr, whereas Agp2 converts slowly from Pr to Pfr. In a previous study, we have assembled Agp1 with synthetic locked chromophores 15Za, 15Zs, 15Ea, and 15Es in which the C15=C16 double bond is fixed in either the E or Z configuration and the C14-C15 single bond is fixed in either the syn (s) or anti (a) conformation. In the present study, the locked chromophores 5Za and 5Zs were used for assembly with Agp1; in these chromophores, the C4=C5 double bond is fixed in the Z configuration, and the C5-C6 single bond is fixed in either the syn or anti conformation. All locked chromophores were also assembled with Agp2. The data showed that in both phytochromes the Pr chromophore adopts a C4=C5 Z C5-C6 syn C15=C16 Z C14-C15 anti stereochemistry and that in the Pfr chromophore the C15=C16 double bond has isomerized to the E configuration, whereas the C14-C15 single bond remains in the anti conformation. Photoconversion shifted the absorption maxima of the 5Zs adducts to shorter wavelengths, whereas the 5Za adducts were shifted to longer wavelengths. Thus, the C5-C6 single bond of the Pfr chromophore is rather in an anti conformation, supporting the previous suggestion that during photoconversion of phytochromes, a rotation around the ring A-B connecting single bond occurs.     

Does restored plant diversity play a role in the reproductive functionality of Banksia populations?

Vegetation structure and plant species diversity of restoration sites are predicted to directly affect pollinator attraction, with potential impacts on gene flow, reproduction, genetic diversity of future generations, and ultimately restoration success. We compared Banksia attenuata R.Br. (Proteaceae) in a low species diversity restoration site and an adjacent natural remnant. We assessed fecundity genetic diversity in adult plants and their offspring, mating system parameters and pollen dispersal using paternity assignment. Results were compared to an earlier study of reproductive functionality within a high species diversity restoration site that was restored in a similar manner, enabling us to investigate any association between plant species diversity and fecundity. Seed set data indicated no significant differences between restored and adjacent natural sites; however, seed set data between restoration sites was significantly different (2.08 ± 0.39 and 6.89 ± 1.12, respectively). The mean number of fruits (follicles) per inflorescence was not significantly different between restoration sites. Genetic diversity of adult plants and their offspring were comparable in all sites. Higher allelic richness and genetic differentiation in one restored site reflected sourcing beyond local provenance. Low correlated paternity indicated high levels of multiple siring of seeds and paternity assignment demonstrated strong genetic connectivity between sites. Reproductive functionality, as measured by fecundity and genetic diversity in the offspring of B. attenuata, is resilient to low species diversity within a restored plant community. We consider our results in the context of establishing seed production areas (SPAs) that maximize the quantity and genetic quality of Banksia seeds for restoration.     

A framework for the practical science necessary to restore sustainable,resilient, and biodiverse ecosystems

Demand for restoration of resilient, self‐sustaining, and biodiverse natural ecosystems as a conservation measure is increasing globally; however, restoration efforts frequently fail to meet standards appropriate for this objective. Achieving these standards requires management underpinned by input from diverse scientific disciplines including ecology, biotechnology, engineering, soil science, ecophysiology, and genetics. Despite increasing restoration research activity, a gap between the immediate needs of restoration practitioners and the outputs of restoration science often limits the effectiveness of restoration programs. Regrettably, studies often fail to identify the practical issues most critical for restoration success. We propose that part of this oversight may result from the absence of a considered statement of the necessary practical restoration science questions. Here we develop a comprehensive framework of the research required to bridge this gap and guide effective restoration. We structure questions in five themes: (1) setting targets and planning for success, (2) sourcing biological material, (3) optimizing establishment, (4) facilitating growth and survival, and (5) restoring resilience, sustainability, and landscape integration. This framework will assist restoration practitioners and scientists to identify knowledge gaps and develop strategic research focused on applied outcomes. The breadth of questions highlights the importance of cross‐discipline collaboration among restoration scientists, and while the program is broad, successful restoration projects have typically invested in many or most of these themes. Achieving restoration ecology's goal of averting biodiversity losses is a vast challenge: investment in appropriate science is urgently needed for ecological restoration to fulfill its potential and meet demand as a conservation tool.     

Chromosome numbers and meiotic analysis in the pre-breeding of <Emphasis Type="BoldItalic">Brachiaria decumbens</Emphasis> (Poaceae)

A total of 44 accessions of Brachiaria decumbens were analysed for chromosome count and meiotic behaviour in order to identify potential progenitors for crosses. Among them, 15 accessions presented 2n = 18; 27 accessions, 2n = 36; and 2 accessions, 2n = 45 chromosomes. Among the diploid accessions, the rate of meiotic abnormalities was low, ranging from 0.82% to 7.93%. In the 27 tetraploid accessions, the rate of meiotic abnormalities ranged from 18.41% to 65.83%. The most common meiotic abnormalities were related to irregular chromosome segregation, but chromosome stickiness and abnormal cytokinesis were observed in low frequency. All abnormalities can compromise pollen viability by generating unbalanced gametes. Based on the chromosome number and meiotic stability, the present study indicates the apomictic tetraploid accessions that can act as male genitor to produce interspecific hybrids with B. ruziziensis or intraspecific hybrids with recently artificially tetraploidized accessions.     

Impact of valency of a glycoprotein B-specific monoclonal antibody on neutralization of herpes simplex virus

Herpes simplex virus (HSV) glycoprotein B (gB) is an integral part of the multicomponent fusion system required for virus entry and cell-cell fusion. Here we investigated the mechanism of viral neutralization by the monoclonal antibody (MAb) 2c, which specifically recognizes the gB of HSV type 1 (HSV-1) and HSV-2. Binding of MAb 2c to a type-common discontinuous epitope of gB resulted in highly efficient neutralization of HSV at the postbinding/prefusion stage and completely abrogated the viral cell-to-cell spread in vitro. Mapping of the antigenic site recognized by MAb 2c to the recently solved crystal structure of the HSV-1 gB ectodomain revealed that its discontinuous epitope is only partially accessible within the observed multidomain trimer conformation of gB, likely representing its postfusion conformation. To investigate how MAb 2c may interact with gB during membrane fusion, we characterized the properties of monovalent (Fab and scFv) and bivalent [IgG and F(ab')(2)] derivatives of MAb 2c. Our data show that the neutralization capacity of MAb 2c is dependent on cross-linkage of gB trimers. As a result, only bivalent derivatives of MAb 2c exhibited high neutralizing activity in vitro. Notably, bivalent MAb 2c not only was capable of preventing mucocutaneous disease in severely immunodeficient NOD/SCID mice upon vaginal HSV-1 challenge but also protected animals even with neuronal HSV infection. We also report for the first time that an anti-gB specific monoclonal antibody prevents HSV-1-induced encephalitis entirely independently from complement activation, antibody-dependent cellular cytotoxicity, and cellular immunity. This indicates the potential for further development of MAb 2c as an anti-HSV drug.     

Tyrosine-based endocytic motifs stimulate oligomerization of AP-2 adaptor complexes

The clathrin adaptor complex AP-2 functions in the assembly of clathrin-coated vesicles at the plasma membrane where it serves to couple endocytic vesicle formation to the selection of membrane cargo proteins. Recent evidence suggests that binding of tyrosine-based endocytic sorting motifs may induce a conformational change within the AP-2 adaptor complex that could enhance its interaction with other cargo molecules and with the membrane. We report here that soluble tyrosine-based endocytic sorting motif peptides facilitate clathrin/AP-2 recruitment to liposomal membranes and induce adaptor oligomerization even in the absence of a lipid bilayer. These effects are specific for endocytic motifs of the type Yxxphi whereas peptides corresponding to NPxY- or di-leucine-containing sorting signals are ineffective. Our data may help to explain how the highly cooperative assembly of clathrin and adaptors could be linked to the selection of membrane cargo proteins.