Testing plant use of mobile vs immobile soil water sources using stable isotope experiments.

We tested for isotope exchange between bound (immobile) and mobile soil water, and whether there is isotope fractionation during plant water uptake. These are critical assumptions to the formulation of the 'two water worlds' hypothesis based on isotope profiles of soil water. In two different soil types, soil-bound water in two sets of 19-l pots, each with a 2-yr-old avocado plant (Persea americana), were identically labeled with tap water. After which, one set received isotopically enriched water whereas the other set received tap water as the mobile phase water. After a dry down period, we analyzed plant stem water as a proxy for soil-bound water as well as total soil water by cryogenic distillation. Seventy-five to 95% of the bound water isotopically exchanged with the mobile water phase. In addition, plants discriminated against 18 O and 2 H during water uptake, and this discrimination is a function of the soil water loss and soil type. The present experiment shows that the assumptions for the 'two water worlds' hypothesis are not supported. We propose a novel explanation for the discrepancy between isotope ratios of the soil water profile and other water compartments in the hydrological cycle.

L-arginine Attenuates Hypobaric Hypoxia-Induced Increase in Ornithine Decarboxylase 1.

BACKGROUND: Chronic hypoxia-induced pulmonary hypertension and vascular remodeling have been shown to be associated with ornithine decarboxylase 1 (ODC1). However, few animal studies have investigated the role of ODC1 in acute hypoxia. OBJECTIVES: We investigated ODC1 gene expression, morphologic and functional changes, and the effect of L-arginine as an attenuator in lung tissues of rats exposed to acute hypobaric hypoxia at a simulated altitude of 6000 m. METHODS: Sprague-Dawley rats exposed to simulated hypobaric hypoxia (6000 m) for 24, 48, or 72 hours were treated with L-arginine (L-arginine group, 20 mg/100 g intraperitoneal; n=15) or untreated (non-L-arginine group, n=15). Control rats (n=5) were maintained at 2260 m in a normal environment for the same amount of time but were treated without L-arginine. The mean pulmonary artery pressure was measured by PowerLab system. The morphologic and immunohistochemical changes in lung tissue were observed under a microscope. The mRNA and protein levels of ODC1 were measured by real-time polymerase chain reaction and Western-blot, respectively. RESULTS: Hypobaric hypoxia induced pulmonary interstitial hyperemia and capillary expansion in the lungs of rats exposed to acute hypoxia at 6000 m. The mean pulmonary artery pressure and the mRNA and protein levels of ODC1 were significantly increased, which could be attenuated by treatment with L-arginine. CONCLUSIONS: L-arginine attenuates acute hypobaric hypoxia-induced increase in mean pulmonary artery pressure and ODC1 gene expression in lung tissues of rats. ODC1 gene contributes to the development of hypoxic pulmonary hypertension.

cDNA sequence encoding metallothionein protein from Aegiceras corniculatum and its gene expression induced by Pb²âº and Cd²âº stresses.

Constructing various green wetland examples for mangrove wetland systems is a useful way to use natural power to remediate the polluted wetlands at intertidal zones. Metallothioneins (MT) are involved in heavy metal tolerance, homeostasis, and detoxification of intracellular metal ions in plants. In order to understand the mechanism of heavy metal uptake in Aegiceras corniculatum, we isolated its metallothionein gene and studied the MT gene expression in response to heavy metals contamination. Here, we report the isolation and characterization of MT2 genes from young stem tissues of A. corniculatum growing in the cadmium (Cd) and lead (Pb) polluted wetlands of Quanzhou Bay, southeast of China. The obtained cDNA sequence of MT is 512 bp in length, and it has an open reading frame encoding 79 amino acid residues with a molecular weight of 7.92 kDa and the theoretical isoelectric point of 4.55. The amino acids include 14 cysteine residues and 14 glycine residues. It is a non-transmembrane hydrophilic protein. Sequence and homology analysis showed the MT protein sequence shared more than 60% homology with other plant type 2 MT-like protein genes. The results suggested that the expression level of MT gene of A. corniculatum young stems induced by a certain range concentration of Cd(2+) and Pb(2+) stresses (0.2 mmol L(-1) Pb(2+), 1 mmol L(-1) Pb(2+), 0.2 mmol L(-1) Pb(2+), and 40 µmmol L(-1) Cd(2+); 1 mmol L(-1) Pb(2+) and 40 µmol L(-1) Cd(2+)) compared with control might show an adaptive protection. The expression levels of MT gene at 20 h stress treatment were higher than those at 480 h stress treatment. The expression levels of MT gene with 0.2 mmol L(-1) Pb(2+) stress treatment were higher than those with 0.2 mmol L(-1) Pb(2+) and 40 µmol L(-1) Cd(2+) stress treatment, and the MT gene expression levels with 1 mmol L(-1) Pb(2+) treatment were higher than those with 1 mmol L(-1) Pb(2+) and 40 µmol L(-1) Cd(2+) treatment. There exists an antagonistic action between Pb(2+) and Cd(2+) in the MT metabolization of A. corniculatum.

Genome wide identification, characterization and expression analysis of HD-ZIP gene family in Cucumis sativus L. under biotic and various abiotic stresses.

Information retrieved from genomic assembly may provide important clues and various molecular aspects in plants. Our research identified 40 CsHDZ genes in the Cucumber genome database. Subsequently; we performed the conserved motif and domain analysis of CsHDZ proteins. The phylogeny of the CsHDZ proteins further divides into 4 subfamilies (HD-ZIP I, HD-ZIP II, HD-ZIP III, and HD-ZIP IV) based on the structural similarities and functional diversities. The GO (Gene ontology) analysis of CsHDZ proteins showed that they are responsive to environmental stimuli and involved in numerous growth and developmental processes. The qRT-PCR analysis of 11 CsHDZ genes showed that they are expressed in all the tested tissues of Cucumis sativus. The differential expression pattern of CsHDZ genes unfolded their possible involvement in responding to various abiotic stresses and powdery mildew stress. It has been found that the CsHDZ22 localized in the nucleus which possibly participates in the regulatory mechanisms of various biological and cellular processes. In the light of above-mentioned outcomes, it has been deducted that CsHDZ genes in the Cucumis sativus genome play an important role in mediating the resistance to various abiotic stresses and powdery mildew stress as well as provide significant clues for functional studies.

Transcriptomic profiling reveals gene expression kinetics in patients with hypoxia and high altitude pulmonary edema.

OBJECTIVE: High altitude pulmonary edema (HAPE) is a life threatening condition occurring in otherwise healthy individuals who rapidly ascend to high altitude. However, the molecular mechanisms of its pathophysiology are not well understood. The objective of this study is to evaluate differential gene expression in patients with HAPE during acute illness and subsequent recovery. METHODS: Twenty-one individuals who ascended to an altitude of 3780 m were studied, including 12 patients who developed HAPE and 9 matched controls without HAPE. Whole-blood samples were collected during acute illness and subsequent recovery for analysis of the expression of hypoxia-related genes, and physiologic and laboratory parameters, including mean pulmonary arterial pressure (mPAP), heart rate, blood pressure, and arterial oxygen saturation (SpO2), were also measured. RESULTS: Compared with control subjects, numerous hypoxia-related genes were up-regulated in patients with acute HAPE. Gene network analyses suggested that HIF-1α played a central role in acute HAPE by affecting a variety of hypoxia-related genes, including BNIP3L, VEGFA, ANGPTL4 and EGLN1. Transcriptomic profiling revealed the expression of most HAPE-induced genes was restored to a normal level during the recovery phase except some key hypoxia response factors, such asBNIP3L, EGR1, MMP9 and VEGF, which remained persistently elevated. CONCLUSIONS: Differential expression analysis of hypoxia-related genes revealed distinct molecular signatures of HAPE during acute and recovery phases. This study may help us to better understand HAPE pathogenesis and putative targets for further investigation and therapeutic intervention.

Regulation effects on abnormal glucose and lipid metabolism of TZQ-F, a new kind of Traditional Chinese Medicine.

AIM OF THE STUDY: Based on the recipe of the traditional anti-diabetic formula TZQ, we developed TZQ-F, a new formula including 8 fractions isolated from Red Paeony root, Mulberry leaf, Lotus leaf, Danshen root and Hawthorn leaf with a good quality assurance. The study was aimed at fraction preparation and effects of the fractions on abnormal glucose and lipid metabolism. MATERIALS AND METHODS: The active fractions were obtained by macroporous resin, ion-exchange resin and polyamide resin column chromatographies. HPLC analyses were used for quality control. In vitro mechanism study included DPPH radical scavenging, AGEs formation inhibition, alpha-glucosidase inhibition and lipase inhibition, and rats on high-fat diet were used for in vivo study. RESULTS: In vitro mechanism study showed that among the 8 fractions, three of them had inhibition effects on intestinal disaccharase, three with inhibition effects on lipase, and five with effects of free radical scavenging. In vivo study showed that after 4 weeks of treatment, TZQ-F significantly decreased the levels of serum total cholesterol, TG, glucose, LDL-C and HDL-C in rats on high-fat diet. Consistent with the in vitro and in vivo results, histology study demonstrated that TZQ-F alleviated hepatic steatosis induced by high-fat diet. CONCLUSIONS: TZQ-F possesses the potential regulation effects on abnormal glucose and lipid metabolism.