Functional diversity of microboring Ostreobium algae isolated from corals

The filamentous chlorophyte Ostreobium sp. dominates shallow marine carbonate microboring communities, and is one of the major agents of reef bioerosion. While its large genetic diversity has emerged, its physiology remains little known, with unexplored relationship between genotypes and phenotypes (endolithic versus free-living growth forms). Here, we isolated nine strains affiliated to two lineages of Ostreobium (>8% sequence divergence of the plastid gene rbcL), one of which was assigned to the family Odoaceae, from the fast-growing coral host Pocillopora acuta Lamarck 1816. Free-living isolates maintained their bioerosive potential, colonizing pre-bleached coral carbonate skeletons. We compared phenotypes, highlighting shifts in pigment and fatty acid compositions, carbon to nitrogen ratios and stable isotope compositions (δ¹³C and δ¹⁵N). Our data show a pattern of higher chlorophyll b and lower arachidonic acid (20:4ω6) content in endolithic versus free-living Ostreobium. Photosynthetic carbon fixation and nitrate uptake, quantified via 8 h pulse-labeling with ¹³C-bicarbonate and ¹⁵N-nitrate, showed lower isotopic enrichment in endolithic compared to free-living filaments. Our results highlight the functional plasticity of Ostreobium phenotypes. The isotope tracer approach opens the way to further study the biogeochemical cycling and trophic ecology of these cryptic algae at coral holobiont and reef scales.     

Effect of novel curcumin‐encapsulated chitosan–bioglass drug on bone and skin repair after gamma radiation: experimental study on a Wistar rat model

Radiation therapy contributes to a significant increase in bone osteoporosis and skin loss. Various natural health products might be beneficial to reduce bone and skin alterations. Curcumin (CUR) medicines derived from natural plants have played an important role in health care. This study aims at synthesizing and evaluating the performance therapy of CUR‐encapsulated bioglass–chitosan (CUR–BG–CH). In vitro, the antioxidant assay was evaluated by using 1,1‐diphenyl‐2‐picrylhydrazyl free‐radical (DPPH) scavenging and the nitroblue tetrazolium reduction. The CUR–BG–CH antimicrobial effects were tested in liquid media. In vivo, after rat ⁶⁰Co γ‐radiation, the tissue wound‐healing process was studied by grafting CUR and CUR–BG–CH in femoral condyle and dorsal skin rat tissue. The antioxidant studies indicated that CUR–BG–CH quenches free radicals more efficiently than unmodified CUR and had effective DPPH (91%) and superoxide anion (51%) radical scavenging activities. The CUR–BG–CH biomaterial exhibited an important antimicrobial activity against Staphylococcus aureus. The histomorphometric parameters showed amelioration in CUR–BG–CH‐treated rats. An improved mechanical property was noticed (33.16 ± 5.0 HV) when compared with that of unmodified CUR group (23.15 ± 4.9 HV). A significant decrease in tumour necrosis factor‐α cytokine production was noted in the CUR–BG–CH rats (90 pg/ml) as compared with that of unmodified CUR group (240 pg/ml). The total amount of hydroxyproline was significantly enhanced (33.5%) in CUR–BG–CH group as compared with that of control. Our findings suggested that CUR–BG–CH might have promising potential applications for wound healing. Copyright © 2015 John Wiley & Sons, Ltd.     

Assessment of population structure,genetic diversity and relationship of Mediterranean olive accessions using SSR markers and computational tools

Biotechnology Letters - Olive tree is an emblematic crop of the Mediterranean region, mainly renowned for its fruit oil, although the species provides several industrial purposes. The Mediterranean...     

Assessing the Potential Role of Zinc Oxide Nanoparticles for Mitigating Cadmium Toxicity in Capsicum annuum L. Under In Vitro Conditions

Journal of Plant Growth Regulation - The application of metal and metal-oxide nanoparticles (NPs) in agriculture to mitigate the abiotic environmental stress factors and pollutants has gained...     

Mpl ligand or thrombopoietin: Biological activities

Thrombopoietin (TPO) or Mpl ligand is the primary physiological regulator of platelet production. This cytokine is the most potent stimulator of the proliferation and differentiation of MK progenitor and precursor cellsin vitro. It also acts additively or synergistically with several cytokines on progenitor cells from various hematopoietic lineages, including the primitive stem cells. The factor is an extremely potent thrombocytopoietic agent when administrated to normal animals, and it accelerates platelet and erythropoietic recovery in several models of myelosuppression. Phase I/II clinical trials are ongoing with no detectable adverse effects. Mpl ligand does not induce platelet aggregation, but it lowers the platelet sensitivity to physiological dose of agonists. In experimental mouse models, high and chronic dose of Mpl ligand results in myelofibrosis. TPO is constantly produced by the liver and the kidney; its plasmatic clearance occurs by binding to its receptor expressed on megakaryocytes and platelets. However, the full spectrum of the biological effects of this new cytokine is not fully understood, in particular its the role in the terminal stage of platelet production. In the near future, it is likely that new insights will be obtained in the physiopathological mechanisms underlying abnormal platelet production in human.     

A G1 cell cycle arrest induced by ligands of the reovirus type 3 receptor is secondary to inactivation of p21ras and mitogen-activated protein kinase.

The reovirus type 3 S1 gene product (type 3 hemagglutinin; HA3) is the viral protein responsible for binding to a mammalian cell-surface receptor. It has been shown that HA3 binding to its receptor inhibits cell growth, even in the continuous presence of serum mitogens. Here, receptor-mediated signal transduction leading to growth arrest was studied after binding with synthetic or recombinant ligands in the absence of viral infection. Receptor ligation caused rapid inactivation of p21(ras), a decrease in Raf phosphorylation and in mitogen-activated protein kinase (MAPK) enzymatic activity, and G1 cell cycle arrest. Transfection and expression of constitutively active v-Has-ras prevented the G1 arrest, indicating that inactivation of p21(ras) is causative. Interestingly, v-Has-ras expression also decreased the efficiency of reoviridae replication, suggesting that inactivation of p21(ras) signals is required at some step of the viral cycle. This study may define new mechanisms regulating cell growth and support the approach of using viral proteins to identify and study cellular receptors. Synthetic receptor ligands with antiproliferative properties may be useful in drug development with the aim of blocking mitosis.