Elucidation of gastrointestinal dysfunction in response to irradiation using metabolomics

Gastrointestinal toxicity is frequently observed secondary to accidental or therapeutic radiation exposure. However, the variation in the intestinal metabolites after abdominal radiation exposure remains ambiguous. In the present study, C57BL/6 mice were exposed to 0, 2, and 20 Gy irradiation dose. The Head and chest of each mouse were covered with a lead shield before x-ray irradiation. 24 h post-irradiation treatment, intestinal tissue of each mouse was excised and prepared for metabolites measurement using gas chromatography-mass spectrometry (GC-MS). Our comprehensive analysis of metabolites in the intestinal tissues detected 44 metabolites after irradiation, including amino acids, carbohydrates, organic acids, and sugars. Amino acid levels in the intestinal tissue gradually rose, dependent on the radiation dose, perhaps as an indication of oxidative stress. Our findings raise the possibility that amino acid metabolism may be a potential target for the development of treatments to alleviate or mitigate the harmful effects of oxidative stress-related gastrointestinal toxicity due to radiation exposure.     

Insulin and glucagon share the same mechanism of neuroprotection in diabetic rats: role of glutamate

In patients with acute ischemic stroke, diabetes and hyperglycemia are associated with increased infarct size, more profound neurologic deficits and higher mortality. Notwithstanding extensive clinical and experimental data, treatment of stroke-associated hyperglycemia with insulin is controversial. In addition to hyperglycemia, diabetes and even early prediabetic insulin resistance are associated with increased levels of amino acids, including the neurotoxic glutamate, in the circulation. The pleiotropic metabolic effects of insulin include a reduction in the concentration of amino acids in the circulation. In this article, we show that in diabetic rats exposed to transient middle cerebral artery occlusion, a decrease of plasma glutamate by insulin or glucagon reduces CSF glutamate, improves brain histology, and preserves neurologic function. The neuroprotective effect of insulin and glucagon was similar, notwithstanding their opposite effects on blood glucose. The therapeutic window of both hormones overlapped with the short duration (~30 min) of elevated brain glutamate following brain trauma in rodents. Similar neuroprotective effects were found after administration of the glutamate scavenger oxaloacetate, which does not affect glucose metabolism. These data indicate that insulin and glucagon exert a neuroprotective effect within a very brief therapeutic window that correlates with their capacity to reduce glutamate, rather than by modifying glucose levels.     

A new lectin from the tuberous rhizome of Kaempferia rotunda: isolation, characterization, antibacterial and antiproliferative activities

A lectin (designated as KRL) was purified from the extracts of Kaempferia rotunda Linn. tuberous rhizome by glucose-sepharose affinity chromatography. KRL was determined to be a 29.0 ± 1.0 kDa polypeptide by SDS-PAGE under both reducing and non-reducing conditions. KRL was a divalent ion dependent glycoprotein with 4% neutral sugar which agglutinated different groups of human blood cells. Methyl-α-D-mannopyranoside, D-mannose and methyl-α-D-glucopyranoside were the most potent inhibitors. N-terminal sequence of KRL showed similarity to some mannose/ glucose specific lectins but the main differences with their molecular masses and sugar content. KRL lost its activity markedly in the presence of denaturants and exhibited high agglutination activity from pH 6.0 to 8.2 and temperature 30 to 60° C. The lectin showed toxicity against brine shrimp nauplii with the LC50 value of 18 ± 6 μg/ml and strong agglutination activity against seven pathogenic bacteria. KRL inhibited the growth of six bacteria partially and did not show antifungal activity. In addition, antiproliferative activity against Ehrlich ascites carcinoma (EAC) cells showed 51% and 67% inhibition in vivo in mice administered 1.25 mg/kg/day and 2.5 mg/kg/day of KRL respectively by injection for five days.     

Metabolic changes of iron uptake in N2-fixing common bean nodules during iron deficiency

Iron is an important nutrient in N₂-fixing legume nodules. The demand for this micronutrient increases during the symbiosis establishment, where the metal is utilized for the synthesis of various iron-containing proteins in both the plant and the bacteroid. Unfortunately, in spite of its importance, iron is poorly available to plant uptake since its solubility is very low when in its oxidized form Fe(III). In the present study, the effect of iron deficiency on the activity of some proteins involved in Strategy I response, such as Fe-chelate reductase (FC-R), H⁺-ATPase, and phosphoenolpyruvate carboxylase (PEPC) and the protein level of iron regulated transporter (IRT1) and H⁺-ATPase proteins has been investigated in both roots and nodules of a tolerant (Flamingo) and a susceptible (Coco blanc) cultivar of common bean plants. The main results of this study show that the symbiotic tolerance of Flamingo can be ascribed to a greater increase in the FC-R and H⁺-ATPase activities in both roots and nodules, leading to a more efficient Fe supply to nodulating tissues. The strong increase in PEPC activity and organic acid content, in the Flamingo root nodules, suggests that under iron deficiency nodules can modify their metabolism in order to sustain those activities necessary to acquire Fe directly from the soil solution.     

Variability in the response of six genotypes of N<Subscript>2</Subscript>-fixing <Emphasis Type="Italic">Medicago ciliaris</Emphasis> to NaCl

Genotypic variability was assessed within six Medicago ciliaris genotypes growing symbiotically with Sinorhizobium medicae in order to identify physiological criteria (growth, ion content, and plant health) associated with salt tolerance. Response to salt stress depended on the line and the level of salt. Two lines with lower dry biomass under non-saline conditions (TNC 1.8 from a semi-arid area and TNC 10.8 from a sub-humid area), were more tolerant to NaCl, whereas the most productive lines (TNC 11.5 and TNC 11.9 from a humid bioclime) were more sensitive in terms of growth and nitrogen fixation. Susceptibility of symbiotic nitrogen fixation to saline stress was not associated with a higher accumulation of Na⁺ in nodules, since the most tolerant lines TNC 1.8 and TNC 10.8 accumulated the highest Na⁺ amount in nodules. Leaf area and net photosynthate assimilation rate were conserved in line TNC 1.8 and to a lesser extent in line TNC 10.8 potentially owing to a greater ability to protect aerial organs and nodules from Na⁺ damage and to insure a better supply of leaves with nitrogen. Our results suggest that nodule growth and number and nodule Na⁺ content should not be used as selection tools for tolerance or susceptibility, since two of the tested lines maintained consistent growth in spite of reduced nodule and high Na⁺ content. Instead, the most reliable physiological indicators for tolerance appear to be consistent growth (i.e., no growth changes) and reduced leaf Na⁺ accumulation with increasing concentrations of NaCl.     

Molecular cloning and expression of long-wavelength-sensitive cone opsin in the brain of a tropical damselfish

Ovarian development of the sapphire devil, Chrysiptera cyanea, exhibits photoperiodism and is stimulated under long-day conditions. Previous studies suggest that red light is more effective than green and blue lights for inducing ovarian development. In addition, the extra-retinal photoreception involved in the ovarian development is suggested in this species. The present study aimed to clone the red-light-sensitive cone opsin (sdLWS) of this species, to demonstrate its expression in the brain, and to confirm the effectiveness of red light on the initiation of ovarian development. A phylogenetic analysis revealed that sdLWS belongs to the long-wavelength-sensitive opsin (LWS opsin) group, showing high identity (77–92%) with the LWS opsin of other fishes. RT-PCR showed that sdLWS is expressed in the eye, brain, and ovary. In situ hybridization indicated that sdLWS is expressed in the third ventricle periventricular area in the anterior hypothalamus. Exposing fish to long-day conditions of red light resulted in the appearance of vitellogenic oocytes in the ovary and an increase in the gonadosomatic index within 2 weeks, suggesting that fish immediately undergo oocyte development under red light conditions. These results indicate that sdLWS is a possible candidate of deep brain photoreceptor molecule involved in photoperiodic ovarian development in the sapphire devil.     

Proteomics Analysis of Embryo and Endosperm from Mature Common Buckwheat Seeds

We used proteomics analysis to generate the profiles of proteins in the endosperm and embryo of common buckwheat grains. These differentially expressed proteins are potentially involved in seed metabolism. Extractions were done by trichloroacetic acid (TCA) precipitation. The resulting proteins were separated using SDS-PAGE coupled to LC-ESI-Q/TOF-MS/MS. This allowed us to detect and identify 67 proteins with isoforms, making this the most inclusive protein profile. The proteins were determined to be functionally involved in the central metabolic pathway of the seed, with metabolic interest being reflected in the occurrence of a tissue-specific enzyme balance. For a case in point, we found a tissue-specific and subcellular compartment-specific isoform of granule-bound starch synthase 1 in the chloroplast/amyloplast. This provided proteomic verification of the presence of a distinct regulatory mechanism for the biosynthesis of glycan and starch, which produce amylase and amylopectin. Furthermore, several previously characterized allergenic proteins such as 11S and 13S globulin seed storage protein were acknowledged in our seed samples, thus representing the potential for proteomics techniques that survey food sources for any incidence of allergens. This protein profile of common buckwheat grain is a new avenue for understanding its seed physiology in dormant stage as well as suggesting commercial applications for the buckwheat industry as buckwheat flour.