Auxin-responsive ROS homeostasis genes display dynamic expression pattern during rice crown root primordia morphogenesis

Reactive oxygen species (ROS) are generated continuously as a by-product of aerobic metabolism in plants. While excessive ROS cause oxidative stresses in cells, they act as signaling molecules when maintained at an optimum concentration through the dynamic equilibrium of ROS metabolizing mechanisms to regulate growth, development and response to environmental stress. Auxin and its crosstalk with other signaling cascades are crucial for maintaining ROS homeostasis and orchestrating root architecture but dissecting the underlying mechanism requires detailed investigation at the molecular level. Rice fibrous root system is primarily composed of shoot-derived adventitious roots (also called crown roots). Here, we uncover auxin-ROS cross-talk during initiation and growth of rice roots. Potassium iodide treatment changes ROS levels that results in an altered rice root architecture. We reveal that auxin induction recover root growth and development defects by recouping level of hydrogen peroxide. By comparing global datasets previously generated by auxin induction and laser capture microdissection-RNA sequencing, we identify the redox-related antioxidants genes from peroxidase, glutathione reductase, glutathione S-transferase, and thioredoxin reductase families whose expression is regulated by the auxin signaling and also display dynamic expression patterns during crown root primordia morphogenesis. The auxin-mediated differential transcriptome data were validated by quantifying expression levels of a set of genes upon auxin induction. Further, in-depth spatio-temporal expression pattern analysis by RNA in situ hybridization shows the spatially restricted expression of selected genes in the developing crown root primordia. Together, our findings uncover molecular components of auxin-ROS crosstalk involved in root organogenesis.

EPR-TL correlation studies on Bi co-doped CaSO4:Dy phosphor

CaSO(4):Dy, CaSO(4):(Dy, Bi) and CaSO(4):Bi phosphors were prepared through re-crystallization method. Thermoluminescence (TL) characteristics of these phosphor samples were investigated. The radiation induced radical ions formed in these phosphors were investigated using electron paramagnetic resonance (EPR) spectroscopy. The main signals observed in both CaSO(4):(Dy, Bi) and CaSO(4):Bi were identified as SO(4)(-) (II), SO(4)(-) (⊥) and SO(3)(-) (isotropic) with "g" values 2.023, 2.0089 and 2.004, respectively. In order to understand the TL mechanism, CaSO(4):(Dy, Bi) phosphor samples were annealed between 100 and 250 °C and their EPR spectra were studied. It was observed that EPR signal intensities reduce drastically in 250 °C annealed phosphor confirming the role of SO(4)(-) and SO(3)(-) types of defect centers in the dosimetric peak. The reduction in the TL sensitivity with increase in Bi(3+) co-dopant in the phosphor samples was correlated with quenching of TL by Bi(3+) ions rather than the reduction in the concentration of the above defect centers. An effort was also made to use the Bi(3+) co-doped CaSO(4):Dy phosphor for dosimetry of chilled or frozen food irradiation.

Results of pediatric oncology group protocol 8104 for infants with stages D and DS neuroblastoma

PURPOSE

We determined the complete response and survival rates for infants with disseminated (stage D) neuroblastoma that followed therapy identical to that for regional disease. In those infants whose disease excluded cortical bone metastases (stage DS), we determined complete response rates achieved either spontaneously or with stage D therapy.

PATIENTS AND METHODS

Eighty-eight patients with metastatic disease received induction chemotherapy followed by a second operation, the results of which determined additional therapy. Twenty-five patients were observed after diagnosis, without chemotherapy, until a second operation.

RESULTS

The complete response (CR) rates for patients with stage D disease after induction chemotherapy and postinduction surgery were 26% and 52%, respectively, and for immediately treated patients with stage DS disease 69% and 77%, respectively. Fifty-four percent of initially observed patients with stage DS disease achieved CR after a second operation; 44% were never treated beyond these two operations. Five-year actuarial survival rates for patients with stage D and for all those with stage DS disease were 60% (SE = 6%) and 90% (SE = 5%), respectively.

CONCLUSIONS

Improved survival rates for patients with stage D disease were achieved on this protocol but remained considerably lower than those for infants with less extensive disease. Rates of survival for patients with stage DS disease were achieved with therapy less aggressive than in published series.

Cyclic nucleotide-dependent enzyme secretion in the rat lacrimal gland

To characterize the role of cyclic nucleotides in secretion of enzymes by the lacrimal gland, pieces of rat exorbital glands were perfused with (1) 8-bromoadenosine-3',5'-cyclic monophosphate (8 Br cyclic AMP), (2) 8-bromoguanosine-3',5'-cyclic monophosphate (8 Br cyclic GMP), (3) forskolin, a stimulator of adenylate cyclase activity, (4) 3-isobutyl-1-methylxanthine (IBMX), an inhibitor of phosphodiesterase activity, or (5) carbachol, a cholinergic agonist. As a measure of enzyme secretion, timed collections of the perifusate effluent were analysed for peroxidase, an enzyme secreted by the lacrimal gland. Control peroxidase secretion was 0.3-0.9 (u./min per milligram protein). Peroxidase secretion was stimulated by 8 Br cyclic AMP (1 mM), but not by 8 Br cyclic GMP (1 mM). A 2-fold increase was detected. Peroxidase secretion was also stimulated by forskolin (60 microM), IBMX (1 mM), and the cholinergic agonist carbachol, which all stimulated peroxidase secretion 2-or 3-fold. The effect of maximally effective concentrations of IBMX (1 mM) and carbachol (0.1 mM) on secretion was additive. Finally, Ca2+ depletion in the presence of EGTA (1 mM) inhibited both IBMX-and carbachol-induced secretion by 45% and 60% respectively. We conclude that cyclic AMP, but not cyclic GMP, can stimulate lacrimal gland enzyme secretion. Cyclic AMP appears to utilize a pathway separate from but convergent with cholinergic agonists.