N-acetylcyteine and flavonoid rich diet:The protective effect of 15 different antioxidants on cigarette smoke-damaged primary human osteoblasts

Cigarette consumption increases oxidative stress in many organs. Increased oxidative stress harms bone cells, which negatively affects bone-matter and -stability. This leads to an increased fracture risk and delayed fracture healing in smokers. A supporting therapy with antioxidants could be of great benefit for surgeons dealing with delayed fracture healing due to increased oxidative stress. In this article we complement and compare our published data with hitherto unpublished data and show the protective effect of 15 different antioxidants on cigarette smoke induced damage in primary human osteoblasts. Exposure to cigarette smoke medium (CSM) rapidly induces formation of ROS in osteoblasts in a concentration- and time-dependent manner. Massive cell damage is seen already after 4 h (EC50 ≈ 0.75 OD320). Pre-, co- and post-incubation with the different antioxidants reduces the formation of ROS and consequently improves the viability of the CSM exposed osteoblasts. Small compounds, e.g. N-acetylcysteine, proved highly effective if pre- or co-incubated before exposure to the CSM. Thus, they are good candidates for acute therapy support as they can be administered in high doses. However, our data suggest that a balanced daily diet could lead to an accumulation of various natural antioxidants (flavonoids) that effectively protect osteoblasts from oxidative stress-induced damage in all three settings investigated. Together with their partly phytoestrogenic properties this may even abate alterations in bone and thus reduce fracture risk on the long run.

Nitrate Transport, Sensing, and Responses in Plants

Nitrogen （N） is an essential macronutrient that affects plant growth and development. N is an important component of chlorophyll, amino acids, nucleic acids, and secondary metabolites. Nitrate is one of the most abundant N sources in the soil. Because nitrate and other N nutrients are often limiting, plants have developed sophisticated mechanisms to ensure adequate supply of nutrients in a variable environment. Nitrate is absorbed in the root and mobilized to other organs by nitrate transporters. Nitrate sensing activates signaling pathways that impinge upon molecular, metabolic, physiological, and developmental responses locally and at the whole plant level. With the advent of genomics technologies and genetic tools, important advances in our understanding of nitrate and other N nutrient responses have been achieved in the past decade. Furthermore, techniques that take advantage of natural polymor- phisms present in divergent individuals from a single species have been essential in uncovering new components. However, there are still gaps in our understanding of how nitrate signaling affects biolog- ical processes in plants. Moreover, we still lack an integrated view of how all the regulatory factors iden- tified interact or crosstalk to orchestrate the myriad N responses plants typically exhibit. In this review, we provide an updated overview of mechanisms by which nitrate is sensed and transported throughout the plant. We discuss signaling components and how nitrate sensing crosstalks with hormonal pathways for developmental responses locally and globally in the plant. Understanding how nitrate impacts on plant metabolism, physiology, and growth and development in plants is key to improving crops for sustainable agriculture.

Arabidopsis thaliana AtUTr7 Encodes a Golgi-Localized UDP-Glucose/UDP-Galactose Transporter that Affects Lateral Root Emergence

Nucleotide sugar transporters （NSTs） are antiporters comprising a gene family that plays a fundamental role in the biosynthesis of complex cell wall polysaccharides and glycoproteins in plants. However, due to the limited number of related mutants that have observable phenotypes, the biological function（s） of most NSTs in cell wall biosynthesis and assembly have remained elusive. Here, we report the characterization of AtUTr7 from Arabidopsis （Arabidopsis thaliana （L.） Heynh.）, which is homologous to multi-specific UDP-sugar transporters from Drosophila melanogaster, humans, and Caenorhabditis elegans. We show that AtUTr7 possesses the common structural characteristics conserved among NSTs. Using a green fluorescent protein （GFP） tagged version, we demonstrate that AtUTr7 is localized in the Golgi apparatus. We also show that AtUTr7 is widely expressed, especially in the roots and in specific floral organs. Additionally, the results of an in vitro nucleotide sugar transport assay carried out with a tobacco and a yeast expression system suggest that AtUTr7 is capable of transferring UDP-Gal and UDP-GIc, but not a range of other UDP- and GDP-sugars, into the Golgi lumen. Mutants lacking expression of AtUTr7 exhibited an early proliferation of lateral roots as well as distorted root hairs when cultivated at high sucrose concentrations. Furthermore, the distribution of homogalacturonan with a low degree of methyl esterification differed in lateral root tips of the mutant compared to wild-type plants, although additional analytical procedures revealed no further differences in the composition of the root cell walls. This evidence suggests that the transport of UDP-Gal and UDP-GIc into the Golgi under conditions of high root biomass production plays a role in lateral root and root hair development.

Loss of Mgat5a-mediated N-glycosylation stimulates regeneration in zebrafish

Background:We are using genetics to identify genes specifically involved in hearing regeneration.In a large-scale genetic screening,we identified mgat5a,a gene in the N-glycosylation biosynthesis pathway whose activity negatively impacts hair cell regeneration.Methods:We used a combination of mutant analysis in zebrafish and a hair cell regeneration assay to phenotype the loss of Mgat5a activity in zebrafish.We used pharmacological inhibition of N-glycosylation by swansonine.We also used over-expression analysis by mRNA injections to demonstrate how changes in N-glycosylation can alter cell signaling.Results:We found that mgat5a was expressed in multiple tissues during zebrafish embryo development,particularly enriched in neural tissues including the brain,retina,and lateral line neuromasts.An mgat5a insertional mutation and a CRISPR/Cas9-generated truncation mutation both caused an enhancement of hair cell regeneration which could be phenocopied by pharmacological inhibition with swansonine.In addition to hair cell regeneration,inhibition of the N-glycosylation pathway also enhanced the regeneration of lateral line axon and caudal fins.Further analysis showed that N-glycosylation altered the responsiveness of TGF-beta signaling.Conclusions:The findings from this study provide experimental evidence for the involvement of N-glycosylation in tissue regeneration and cell signaling.

iPlant Systems Biology (iPSB): An International Network Hub in the Plant Community

sequenced genome of a multicellular organism (Arabidopsis Genome, 2000) completed just after those of the nematode Caenorhabditis elegans (C. elegans Sequencing Consortium, 1998) and the fruit fly Drosophila melanogaster (Adams et al., 2000). Availability of a full whole-genome sequence for the reference plant opened to plant biologists what is commonly called the post-genomic era.

Emerging Players in the Nitrate Signaling Pathway

Nitrogen （N）-based fertilizers are routinely used to increase agricultural productivity for both food and non-food uses of crops. Unfortunately, excess N fertilizers escape to the environment, leading to detrimental effects on the ecosystem and human health. Understanding how plants sense and respond to different N nutrients or metabolites to regulate metabolism, physiology, growth, and development is essential for sustained yields while reducing agriculture＇s environmental and economic costs.