The novel ethylene antagonist, 3-cyclopropyl-1-enyl-propanoic acid sodium salt (CPAS), increases grain yield in wheat by delaying leaf senescence

Orchid is a major floral crop around the world and Dendrobium hybrids are considered to be one of the most popular orchids. In vitro germination of hybrid seeds is a common practice among orchid growers, however, in many cross pollinations the embryos may not develop to maturity, leading to poor seed germination. The effect of seed maturity and sucrose concentration were investigated via asymbiotic germination of nobile Dendrobium hybrids. Capsules were harvested from two hybrids (Den. Lucky Girl × Den. Second Love ‘Kirameki’ and Den. Lucky Girl × Den. Hamana Lake ‘Kumi’) and one selfing of Den. Second Love ‘Kirameki’ at 2, 3, 4, and 5 months after pollination and immature seeds were taken. Immature seeds from 3- to 5-month old capsules could be successfully germinated on Hyponex based medium. Immature seeds from 4-month old capsules showed greatest germination rate of tested treatments, whereas 3-month old immature seeds showed the least germination. After 6 weeks of in vitro culture, protocorms derived from embryos developed on every concentration of sucrose, but germination was greater at lower concentrations. Greater concentration of sucrose decreased normal-developed protocorms.     

Cross-scale drivers of plant trait distributions in a fragmented forest landscape

During community assembly, plant functional traits are under selective pressure from processes operating at multiple spatial scales. However, in fragmented landscapes, there is little understanding of the relative importance of local-, patch- and landscape-scale processes in shaping trait distributions. Here, we investigate cross-scale influences of landscape change on traits that dictate plant life history strategies in re-assembling plant communities in a fragmented landscape in eastern China. Using forest dynamics plots (FDPs) on 29 land-bridge islands in which all woody plants have been georeferenced and identified to species, we characterized and derived two composite measures of trait variation, representing variation across the leaf economics spectrum and plant size. We then tested for trait shifts in response to local-, patch- and landscape-scale factors, and their potential cross-scale interactions. We found substantial community-wide trait changes along local-scale gradients (i.e. forest edge to interior): more acquisitive leaf economic traits and larger sized species occurred at edges, with a significant increase in trait means and trait range. Moreover, there were significant cross-scale interaction effects of patch and landscape variables on local-scale edge effects. Altered spatial arrangement of habitat in the surrounding landscape (i.e. declining habitat amount and increasing patch density), as well as decreasing area at the patch level, exacerbated edge effects on traits distributions. We suggest that synergistic interactions of landscape- and patch-scale processes, such as dispersal limitation, on local-scale environmental filtering at edges, together shape the spatial distributions of plant life history strategies in fragmented plant communities.     

A single-chain class II MHC-IgG3 fusion protein inhibits autoimmune arthritis by induction of antigen-specific hyporesponsiveness

T cells play a central role in many autoimmune diseases. A method to specifically target the function of autoreactive T cell clones would avoid the global immunosuppression associated with current therapies. To develop a molecule capable of inhibiting autoreactive T cell responses in vivo, single-chain peptide-I-A-IgG3 fusion proteins were constructed and expressed in both mammalian and insect cells. The fusion proteins were designed with an IgG3 Fc moiety to make them divalent, allowing TCR cross-linking, while lacking FcR binding and costimulation. The fusion proteins stimulated T cell hybridomas in vitro in a peptide-specific, MHC-restricted manner but failed to do so in soluble form. In vivo administration of an I-A(q) fusion protein, containing an immunodominant collagen II peptide, significantly delayed the onset and reduced the severity of collagen-induced arthritis in DBA/1 mice by induction of Ag-specific hyporesponsiveness. Such fusion proteins may be useful to study novel therapeutic approaches for T cell-mediated autoimmune diseases.     

Ischemic preconditioning decreases the reperfusion-related formation of hydroxyl radicals in a rabbit model of regional myocardial ischemia and reperfusion: the role of K(ATP) channels

The objective of this study was to assess the effects of ischemic preconditioning (IP) on hydroxyl free radical production in an in vivo rabbit model of regional ischemia and reperfusion. Another goal was to determine whether K_ATP channels are involved in these effects.

The hearts of anesthetized and mechanically ventilated New Zealand White rabbits were exposed through a left thoracotomy. After IV salicylate (100 mg/kg) administration, all animals underwent a 30-min stabilization period followed by 40 min of regional ischemia and 2 h of reperfusion. In the IP group, IP was elicited by 5 min of ischemia followed by 10 min of reperfusion (prior to the 40-min ischemia period). Glibenclamide, a K_ATP channel blocker, was administered prior to the preconditioning stimulus. Infarct size was measured by 2,3,5-triphenyl tetrazolium chloride (TTC) staining. We quantified the hydroxyl-mediated conversion of salicylate to its 2,3 and 2,5-dihydroxybenzoate derivatives during reperfusion by high performance liquid chromatography coupled with electro-chemical detection.

IP was evidenced by reduced infarct size compared to control animals: 22% vs. 58%, respectively. Glibenclamide inhibited this cardioprotective effect and infarct size was 53%. IP limited the increase in 2,3 and 2,5-dihydroxybenzoic acid to 24.3 and 23.8% above baseline, respectively. Glibenclamide abrogated this effect and the increase in 2,3 and 2,5-dihydroxybenzoic acid was 94.3 and 85% above baseline levels, respectively, similar to the increase in the control group. We demonstrated that IP decreased the formation of hydroxyl radicals during reperfusion. The fact that glibenclamide inhibited this effect, indicates that K_ATP channels play a key role in this cardioprotective effect of IP.     

Oncologic Trogocytosis of an Original Stromal Cells Induces Chemoresistance of Ovarian Tumours

Background

The microenvironment plays a major role in the onset and progression of metastasis. Epithelial ovarian cancer (EOC) tends to metastasize to the peritoneal cavity where interactions within the microenvironment might lead to chemoresistance. Mesothelial cells are important actors of the peritoneal homeostasis; we determined their role in the acquisition of chemoresistance of ovarian tumours.

Methodology/Principal Findings

We isolated an original type of stromal cells, referred to as “Hospicells” from ascitis of patients with ovarian carcinosis using limiting dilution. We studied their ability to confer chemoresistance through heterocellular interactions. These stromal cells displayed a new phenotype with positive immunostaining for CD9, CD10, CD29, CD146, CD166 and Multi drug resistance protein. They preferentially interacted with epithelial ovarian cancer cells. This interaction induced chemoresistance to platin and taxans with the implication of multi-drug resistance proteins. This contact enabled EOC cells to capture patches of the Hospicells membrane through oncologic trogocytosis, therefore acquiring their functional P-gp proteins and thus developing chemoresistance. Presence of Hospicells on ovarian cancer tissue micro-array from patients with neo-adjuvant chemotherapy was also significantly associated to chemoresistance.

Conclusions/Significance

This is the first report of trogocytosis occurring between a cancer cell and an original type of stromal cell. This interaction induced autonomous acquisition of chemoresistance. The presence of stromal cells within patient''s tumour might be predictive of chemoresistance. The specific interaction between cancer cells and stromal cells might be targeted during chemotherapy.     

Spray Nozzles,Pressures, Additives and Stirring Time on Viability and Pathogenicity of Entomopathogenic Nematodes (Nematoda: Rhabditida) for Greenhouses

The objective of this study was to evaluate different strategies for the application of entomopathogenic nematodes (EPN). Three different models of spray nozzles with air induction (AI 11003, TTI 11003 and AD-IA 11004), three spray pressures (207, 413 and 720 kPa), four different additives for tank mixtures (cane molasses, mineral oil, vegetable oil and glycerin) and the influence of tank mixture stirring time were all evaluated for their effect on EPN (Steinernema feltiae) viability and pathogenicity. The different nozzles, at pressures of up to 620 kPa, were found to be compatible with S. feltiae. Vegetable oil, mineral oil and molasses were found to be compatible adjuvants for S. feltiae, and stirring in a motorized backpack sprayer for 30 minutes did not impact the viability or pathogenicity of this nematode. Appropriate techniques for the application of nematodes with backpack sprayers are discussed.     

Bacterial Cellulose-Binding Domain Modulates in Vitro Elongation of Different Plant Cells

Recombinant cellulose-binding domain (CBD) derived from the cellulolytic bacterium Clostridium cellulovorans was found to modulate the elongation of different plant cells in vitro. In peach (Prunus persica L.) pollen tubes, maximum elongation was observed at 50 μg mL⁻¹ CBD. Pollen tube staining with calcofluor showed a loss of crystallinity in the tip zone of CBD-treated pollen tubes. At low concentrations CBD enhanced elongation of Arabidopsis roots. At high concentrations CBD dramatically inhibited root elongation in a dose-responsive manner. Maximum effect on root hair elongation was at 100 μg mL⁻¹, whereas root elongation was inhibited at that concentration. CBD was found to compete with xyloglucan for binding to cellulose when CBD was added first to the cellulose, before the addition of xyloglucan. When Acetobacter xylinum L. was used as a model system, CBD was found to increase the rate of cellulose synthase in a dose-responsive manner, up to 5-fold compared with the control. Electron microscopy examination of the cellulose ribbons produced by A. xylinum showed that CBD treatment resulted in a splayed ribbon composed of separate fibrillar subunits, compared with a thin, uniform ribbon in the control.