Rhizobacteria associated with Miscanthus x giganteus improve metal accumulation and plant growth in the flotation tailings

Plant and Soil - Flotation tailings represent an extremely unfriendly substrate for plant colonization due to toxic metal concentrations and marked macronutrient deficiencies. The perennial grass...     

Impact of abscisic acid in overcoming the problem of albinism in horse chestnut androgenic embryos

Horse chestnut (Aesculus hyppocastanum L., Hyppocastanacea) is a relict species with a slow and complex reproductive cycle considered to have horticultural and medical importance. The cycle maybe circumvented via in vitro androgenesis. Androgenesis of horse chestnut was induced in microspores and anther culture on MS media. Some of the horse chestnut androgenic embryos were albinos. Addition of abscisic acid in media (in concentrations of 0.01, 0.1, 0.5, 1, 2, 5, 10, and 20 mg l^?1) with horse chestnut androgenic embryos has circumvented the reproduction cycle barriers. The best results were achieved on medium with the lowest abscisic acid concentration (0.01 mg l^?1) in microspore culture. The microspore culture proved to be a better model system for embryo production and albino embryo reduction than anther culture. Flow cytometry analysis after maturation treatments induced by ABA showed that 88 % of green embryos originating from microspore culture were haploid. However, 50 % of green embryos from anther culture were haploid. The remaining analyzed androgenic embryos, from both types of cultures were diploid.     

Engineering Multi-Walled Carbon Nanotube Therapeutic Bionanofluids to Selectively Target Papillary Thyroid Cancer Cells

Background

The incidence of papillary thyroid carcinoma (PTC) has risen steadily over the past few decades as well as the recurrence rates. It has been proposed that targeted ablative physical therapy could be a therapeutic modality in thyroid cancer. Targeted bio-affinity functionalized multi-walled carbon nanotubes (BioNanofluid) act locally, to efficiently convert external light energy to heat thereby specifically killing cancer cells. This may represent a promising new cancer therapeutic modality, advancing beyond conventional laser ablation and other nanoparticle approaches.

Methods

Thyroid Stimulating Hormone Receptor (TSHR) was selected as a target for PTC cells, due to its wide expression. Either TSHR antibodies or Thyrogen or purified TSH (Thyrotropin) were chemically conjugated to our functionalized Bionanofluid. A diode laser system (532 nm) was used to illuminate a PTC cell line for set exposure times. Cell death was assessed using Trypan Blue staining.

Results

TSHR-targeted BioNanofluids were capable of selectively ablating BCPAP, a TSHR-positive PTC cell line, while not TSHR-null NSC-34 cells. We determined that a 2:1 BCPAP cell:α-TSHR-BioNanofluid conjugate ratio and a 30 second laser exposure killed approximately 60% of the BCPAP cells, while 65% and >70% of cells were ablated using Thyrotropin- and Thyrogen-BioNanofluid conjugates, respectively. Furthermore, minimal non-targeted killing was observed using selective controls.

Conclusion

A BioNanofluid platform offering a potential therapeutic path for papillary thyroid cancer has been investigated, with our in vitro results suggesting the development of a potent and rapid method of selective cancer cell killing. Therefore, BioNanofluid treatment emphasizes the need for new technology to treat patients with local recurrence and metastatic disease who are currently undergoing either re-operative neck explorations, repeated administration of radioactive iodine and as a last resort external beam radiation or chemotherapy, with fewer side effects and improved quality of life.     

A model for non-viral gene delivery: through syndecan adhesion molecules and powered by actin

BACKGROUND: Cell transfection requires cationic DNA complexes and heparan sulfate proteoglycans (HSPGs) at the cell surface. Syndecans are transmembrane HSPGs that are ubiquitously expressed on adherent cells. Their polyanionic heparan sulfate moieties are bound at the distal end of their ectodomain, thus facilitating interaction with large cationic particles. METHODS: We propose a model for cell entry involving syndecans as receptors for the DNA complexes by comparing transfection with bacteria uptake and using drug inhibition experiments along with confocal microscopy. RESULTS: When combined with results from the literature, our data suggest the following sequence of events: after initial particle binding, gradual electrostatic zippering of the plasma membrane onto the particle is sustained by lateral diffusion of syndecan molecules that cluster into cholesterol-rich rafts. Clustering in turn triggers PKC activity and linker protein-mediated actin binding to the cytoplasmic tail of the syndecans. Resulting tension fibers and a growing network of cortical actin may then pull the particle into the cell. CONCLUSIONS: Diversion of integrin- and syndecan-mediated cell adhesion processes for particle engulfment appears to be widely exploited by animals (chylomicrons), by pathogens (bacteria, viruses) and, as suggested here, by non-viral vectors.     

Vav1 and Ly-GDI two regulators of Rho GTPases,function cooperatively as signal transducers in T cell antigen receptor-induced pathways

The Rho family GTPases are pivotal for T cell signaling; however, the regulation of these proteins is not fully known. One well studied regulator of Rho GTPases is Vav1; a hematopoietic cell-specific guanine nucleotide exchange factor critical for signaling in T cells, including stimulation of the nuclear factor of activated T cells (NFAT). Surprisingly, Vav1 associates with Ly-GDI, a hematopoietic cell-specific guanine nucleotide dissociation inhibitor of Rac. Here, we studied the functional significance of the interaction between Vav1 and Ly-GDI in T cells. Upon organization of the immunological synapse, both Ly-GDI and Vav1 relocalize to T cell extensions in contact with the antigen-presenting cell. Ly-GDI is phosphorylated on tyrosine residues following T cell receptor stimulation, and it associates with the Src homology 2 region of an adapter protein, Shc. In addition, the interaction between Ly-GDI and Vav1 requires tyrosine phosphorylation. Overexpression of Ly-GDI alone is inhibitory to NFAT stimulation and calcium mobilization. However, when co-expressed with Vav1, Ly-GDI enhances Vav1 induction of NFAT activation, phospholipase Cgamma phosphorylation, and calcium mobilization. Moreover, Ly-GDI does not alter the regulation of these phenomena when coexpressed with oncogenic Vav1. Since oncogenic Vav1 does not bind Ly-GDI, this suggests that the functional cooperativity of Ly-GDI and Vav1 is dependent upon their association. Thus, our data suggest that the interaction of Vav1 and Ly-GDI creates a fine tuning mechanism for the regulation of intracellular signaling pathways leading to NFAT stimulation.     

Id2 negatively regulates B cell differentiation in the spleen

Early stages of B cell development occur in the bone marrow, resulting in formation of immature B cells. These immature cells migrate to the spleen where they differentiate into mature (B2 or marginal zone (MZ)) cells. This final maturation step is crucial for B cells to become responsive to Ags and to participate in the immune response. Id2 is a helix-loop-helix protein that lacks a DNA-binding region; and therefore, inhibits basic helix-loop-helix functions in a dominant negative manner. In this study, we show that Id2 expression is down-regulated during differentiation of immature B cells into mature B2 and MZ B cells. The high levels of Id2 expressed in the immature B cells result in inhibition of E2A binding activity to an E2 box site. Moreover, mice lacking Id2 show an elevation in the proportion of mature B2 cells in the spleen, while the MZ population in these mice is almost absent. Thus, Id2 acts as a regulator of the differentiation of immature B cells occurring in the spleen, it negatively controls differentiation into mature B2 cells while allowing the commitment to MZ B cells. In the absence of Id2 control, the unregulated differentiation is directed toward the mature B2 population.     

Preferential Th1 immune response in invariant chain-deficient mice

MHC class II molecules associate with the invariant chain (Ii) molecule during biosynthesis. Ii facilitates the folding of class II molecules, interferes with their peptide association, and is involved in MHC class II transport. In this study, we have investigated the in vitro and in vivo immune response of Ii-deficient mice (Ii(-/-)). Our results have demonstrated that CD4(+) T cells from Ii(-/-) mice proliferate normally in vitro after in vivo immunization with protein Ags. However, cytokine secretion profiles of Ag-primed CD4(+) T cells from Ii(-/-) mice differ from CD4(+) T cells from wild-type mice. Whereas cells from wild-type mice secrete IFN-gamma and IL-4, cells from Ii(-/-) mice secrete mostly IFN-gamma. Moreover, Ii(-/-) mice exhibit a normal Th1 response in the delayed-type hypersensitivity and trinitrobenzene sulfonic acid colitis models; however, these mice lack an in vivo Th2 response, as demonstrated in the asthma model. Therefore, we suggest that defective Ag presentation in Ii(-/-) mice leads selectively to a Th1 effector response.     

Fluorescence imaging of lipid peroxidation in isolated rat lungs during nonhypoxic lung ischemia

We have shown previously that ischemia results in reactive oxygen species production by lung endothelium that occurs within 3-5 s after flow cessation and is followed by lipid peroxidation at 15-30 min as determined by assay of thiobarbituric acid-reactive substances, conjugated dienes, and protein carbonyls in lung homogenate. The present study evaluated membrane lipid peroxidation in isolated, ventilated rat lungs using a fluorescence imaging method that permits continuous observation of pulmonary subpleural microvascular endothelial cells in situ. Diphenyl-1-pyrenylphosphine (DPPP), a fluorescent probe which localizes in the plasma membrane and shows increased fluorescence emission after its oxidation by lipid hydroperoxides, was used for detection of membrane lipid peroxidation. Compared to continuously perfused control lungs, endothelial cell DPPP fluorescence increased significantly within 1 min of ischemia (i.e., flow cessation); these changes were prevented by pretreatment with 0.5 mM alpha-tocopherol succinate (vitamin E) added to the perfusate. Increased DPPP fluorescence was confirmed by spectrofluorometry of lipid extracts of lung homogenates. These data indicate that DPPP can be used for the real-time detection of lipid peroxidation in an intact organ. Ischemia results in peroxidation of the pulmonary microvascular endothelial cell membrane and this insult can be detected as early as 1 min after the onset of ischemia compatible with a radical-mediated process.