Chronic administration of a nitric oxide synthase inhibitor,Nω-nitro-l-arginine,and drug-induced increase in cerebellar cyclic GMP in vivo

N-nitro-l-arginine (N^G-nitro-l-arginine) is a potent nitric oxide synthase inhibitor which crosses the blood brain barrier and does not undergo extensive metabolism in vivo. In this study, effect of chronic pretreatment of N-nitro-l-arginine (75 mg/kg, i.p., twice daily for 7 days) on the harmaline- (100 mg/kg, s.c.), picrotoxin- (4 mg/kg, s.c.), pentylenetetrazole- (50 mg/kg, i.p.), andl-glutamic acid- (400 g/10 l/mouse, i.c.v.) induced increase in cerebellar cGMP was assessed. All the four drugs produced significant increase in cerebellar cGMP in vehicle pretreated control animals. Cerebellar cGMP increase induced by harmaline, picrotoxin, andl-glutamic acid was attentuated in N-nitro-l-arginine pretreated animals. These results indicate that in vivo cerebellar cGMP levels are increased by the prototype excitatory amino acid receptor agonist,l-glutamic acid and also by the drugs which augment the excitatory amino acid transmission. Furthermore, parenteral chronic administration of N-nitro-l-arginine blocks NO synthase in the brain and hence cerebellar cGMP response in chronic N-nitro-l-arginine treated animals could be used as a tool to assess the physiological functions of nitric oxide in vivo.Part of this work was presented at the Experimental Biology 93 FASEB Meeting at New Orleans, March 1993.     

Identification of a UDP-glucosyltransferase conferring deoxynivalenol resistance in Aegilops tauschii and wheat

Aegilops tauschii is the diploid progenitor of the wheat D subgenome and a valuable resource for wheat breeding, yet, genetic analysis of resistance against Fusarium head blight (FHB) and the major Fusarium mycotoxin deoxynivalenol (DON) is lacking. We treated a panel of 147 Ae. tauschii accessions with either Fusarium graminearum spores or DON solution and recorded the associated disease spread or toxin-induced bleaching. A k-mer-based association mapping pipeline dissected the genetic basis of resistance and identified candidate genes. After DON infiltration nine accessions revealed severe bleaching symptoms concomitant with lower conversion rates of DON into the non-toxic DON-3-O-glucoside. We identified the gene AET5Gv20385300 on chromosome 5D encoding a uridine diphosphate (UDP)-glucosyltransferase (UGT) as the causal variant and the mutant allele resulting in a truncated protein was only found in the nine susceptible accessions. This UGT is also polymorphic in hexaploid wheat and when expressed in Saccharomyces cerevisiae only the full-length gene conferred resistance against DON. Analysing the D subgenome helped to elucidate the genetic control of FHB resistance and identified a UGT involved in DON detoxification in Ae. tauschii and hexaploid wheat. This resistance mechanism is highly conserved since the UGT is orthologous to the barley UGT HvUGT13248 indicating descent from a common ancestor of wheat and barley.     

Speed Breeding Opportunities and Challenges for Crop Improvement

Journal of Plant Growth Regulation - Crop improvement in light of the rapidly changing climate and the increasing human population continues to be one of the primary concerns for researchers across...     

Chemodiversity and α-Glucosidase Activity of Eucalyptus Species from Northwestern Himalaya,India

The aim of current work was to determine essential oils (EOs) composition from three Eucalyptus species, including E. citriodora, E. camaldulensis and E. globulus and assess their α-glucosidase inhibitory activity. The EOs were collected using the hydrodistillation technique and characterized by GC/MS, GC-FID and NMR. The isolated EOs from leaves parts of Eucalyptus species varied from 0.56 to 1.0 % on fresh weight basis. The content of the EOs was distinct according to the species. The most abundant metabolites were identified as citronellal (0–83.0 %), 1,8-cineole (0.2–44.8 %), spathulenol (0.4–16.1 %) α-pinene (0.4–15.9 %), p-cymene (3.7–11.9 %), citronellol (0–8.6 %), β-eudesmol (5.3–8.6 %) and β-pinene (0–7.1 %). The EOs obtained from targeted samples exhibited strong α-glucosidase inhibitory activity. These results are encouraging and underline that the EOs of Eucalyptus species may be a promising alternative source of natural antidiabetic.     

Production of ethanol from guava pulp by yeast strains

Guava pulp used for ethanol production by three yeast strains contained 10% (w/v) total sugars and was pH 4.1. Ethanol production at the optimum sugar concentration of 10%, at pH 4.1 and 30°C was 1.5%, 3.6% and 3.9% (w/v) by Saccharomyces cerevisiae MTCC 1972, Isolate-1 and Isolate-2, respectively, at 60 h fermentation. Higher sugar concentrations at 15 and 20% were inhibitory for ethanol production by all test cultures. The maximum production of ethanol at optimum natural sugar concentration (10%) of guava pulp, was 5.8% (w/v) at pH 5.0 by Isolate-2 over 36 h fermentation, which was only slightly more than the quantity of ethanol produced by Saccharomyces cerevisiae (5.0%) and Isolate-1 (5.3%) over 36 and 60h fermentation, respectively.     

Effect of boron on the pollen vitality and yield of rice plants (Oryza sativa L. var. Jaya)

Summary Rice plants were grown in sand cultures with nutrient solution including boron at 0, 1, 2.5 and 5 ppm concentrations.In general, supply of boron improved the pollen vitality of rice flowers. It was stimulating up to 2.5 ppm concentration in the nutrient solution, beyond which (i.e., at 5 ppm) inhibitory effects appeared. The availability of boron also increased the yield of rice grains in the same order.Stimulating effects of boron may be linked with greater availability of sugars, increased enzymatic activity and respiration which favoured better growth of pollen. Inhibitory effects of stronger concentration of boron (5 ppm) may be related with physiological depression and injury to protoplasm itself.     

Fluorine-18 labeling of monoclonal antibodies and fragments with preservation of immunoreactivity

A new method is reported for labeling proteins with the positron-emitting nuclide 18F. Initially, 4-[18F]-fluorobenzylamine was prepared in two steps from aqueous [18F]fluoride in high yield. The 18F acylation agent was formed by reaction of this product with disuccinimidyl suberate. Overall yields for the 4-[18F]fluorobenzylamine succinimidyl ester ([18F]SFBS), decay corrected to the end of cyclotron bombardment, were about 30% in a synthesis time of 60 min. After a 15-min reaction, 30-45% (decay corrected) of the [18F]SFBS could be coupled to intact antibodies and their F(ab')2 and Fab fragments. Coupling yields were dependent on protein concentration but not reaction time. HPLC purification of [18F]SFBS was necessary to obtain optimal coupling efficiency and immunoreactivity. The immunoreactivities of 18F-labeled F(ab')2 and Fab fragments of an antimyosin antibody were 89 +/- 5% and 75 +/- 9%, respectively. Biodistribution studies in normal mice demonstrated similar in vivo behavior of 18F-labeled antibody fragments and those labeled with 125I by using N-succinimidyl 3-[125I]iodobenzoate. These results indicate that this method may be useful for labeling monoclonal antibodies and other proteins and peptides with 18F.     

N-succinimidyl 5-(trialkylstannyl)-3-pyridinecarboxylates: a new class of reagents for protein radioiodination

N-Succinimidyl 5-(trialkylstannyl)-3-pyridinecarboxylates (alkyl = Me, Bu) have been prepared and used as a precursor to label N-succinimidyl 5-[131I]iodo-3-pyridinecarboxylate (SIPC). SIPC was obtained in greater than 80% yield from either the methyl or butyl precursor with N-chlorosuccinimide and heating at 60-65 degrees C. Significantly lower yields were observed with tert-butyl hydroperoxide. After a 30-min incubation with [131I]SIPC at pH 8.5, goat IgG, an intact monoclonal antibody (MAb), and a MAb F(ab')2 fragment were labeled in 60-65% yield. Specific binding of the MAb and MAb fragment after SIPC labeling was identical with that observed with N-succinimidyl 3-iodobenzoate and higher than that reported previously for these MAbs after labeling by using the Iodogen method. When 5-[131I]iodonicotinic acid was injected into normal mice, thyroid uptake was less than 0.2% of the injected dose, reflecting the inertness of this compound to deiodination. Paired-label biodistribution studies indicate that for both the MAb and the F(ab')2 labeled by using SIPC, accumulation of activity in the thyroid and other tissues is comparable to that observed when these proteins were labeled by using N-succinimidyl 3-iodobenzoate. The results of this study suggest that SIPC may be a reagent for labeling MAbs with halogen nuclides.