Lifespan extension in hypomorphic daf-2 mutants of Caenorhabditis elegans is partially mediated by glutathione transferase CeGSTP2-2

Electrophilic stress caused by lipid peroxidation products such as 4-hydroxynonenal (4-HNE) and/or related compounds may contribute to aging. The major mode of 4-HNE metabolism involves glutathione conjugation catalyzed by specialized glutathione transferases. We have previously shown that glutathione transferase CeGSTP2-2, the product of the Caenorhabditis elegans gst-10 gene, has the ability to conjugate 4-HNE, and that its overexpression extends lifespan of C. elegans. We now demonstrate that the expression level of CeGSTP2-2 correlates highly with lifespan in a series of hypomorphic daf-2 mutants of C. elegans. The overexpression of CeGSTP2-2 in daf-2 is abrogated in daf-16; daf-2 mutants, indicating that expression of the gst-10 gene is modulated by insulin-like growth factor signaling. To determine whether the relationship between CeGSTP2-2 and lifespan is causal, we used RNAi to knock down CeGSTP2-2. Treatment with gst-10-specific dsRNA decreased CeGSTP2-2 protein in wild-type N2 and in daf-2 strains to an approximately equal level. The ability to conjugate 4-HNE was similarly decreased by RNAi, suggesting that the increment of that activity in daf-2 over N2 is due largely to the overexpression of CeGSTP2-2. RNAi-mediated knock-down of CeGSTP2-2 led to an increased susceptibility to 4-HNE, paraquat, and heat shock, and to a shortening of lifespan by 13% in both N2 and daf-2 strains. These results indicate that CeGSTP2-2 significantly contributes to the maintenance of the soma, and that this function is augmented in daf-2 mutants concordantly with other longevity assurance genes, probably via insulin-like growth factor signaling.     

Structural and luminescent studies of erbium‐doped CaZrO3 green‐emitting nanophosphors

Erbium (Er) (0.5, 1.0 and 1.5 wt%)‐doped CaZrO₃ nanophosphors were synthesized by the sol–gel method using poly(vinyl alcohol) as the chelating agent. Their structural and photoluminescence properties were studied using X‐ray diffraction (XRD), field emission scanning electron microscopy–energy dispersive spectroscopy (FESEM‐EDS), transmission electron microscopy (TEM), photoluminescence and Fourier transform infrared spectroscopy (FTIR). The XRD patterns of the samples confirm that nanoscale crystallite sizes. Agglomeration of the samples was observed using field emission scanning electron microscopy images. Energy dispersive spectroscopy measurements confirmed the existence of Ca, Zr, O and Er in the samples. Average particle sizes for the samples were calculated from transmission electron microscopy images. FTIR spectra clearly show characteristic absorption bands related to the metal oxides, as well as some other organic molecules. The photoluminescence spectra show bands in the green region. The Commission International de l'Eclairage coordinates were calculated and found to be in green region.     

Host plant genetic control of associated fungal and insect species in a Populus hybrid cross

Plants employ a diverse set of defense mechanisms to mediate interactions with insects and fungi. These relationships can leave lasting impacts on host plant genome structure such as rapid expansion of gene families through tandem duplication. These genomic signatures provide important clues about the complexities of plant/biotic stress interactions and evolution. We used a pseudo‐backcross hybrid family to identify quantitative trait loci (QTL) controlling associations between Populus trees and several common Populus diseases and insects. Using whole‐genome sequences from each parent, we identified candidate genes that may mediate these interactions. Candidates were partially validated using mass spectrometry to identify corresponding QTL for defensive compounds. We detected significant QTL for two interacting fungal pathogens and three insects. The QTL intervals contained candidate genes potentially involved in physical and chemical mechanisms of host–plant resistance and susceptibility. In particular, we identified adjoining QTLs for a phenolic glycoside and Phyllocolpa sawfly abundance. There was also significant enrichment of recent tandem duplications in the genomic intervals of the native parent, but not the exotic parent. Tandem gene duplication may be an important mechanism for rapid response to biotic stressors, enabling trees with long juvenile periods to reach maturity despite many coevolving biotic stressors.     

Analysis of 26 amino acids in human plasma by HPLC using AQC as derivatizing agent and its application in metabolic laboratory

The present study reports the simultaneous analysis of 26 physiological amino acids in plasma along with total cysteine and homocysteine by high-performance liquid chromatography (HPLC) employing 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) as precolumn derivatizing reagent. Separations were carried out using Lichrospher 100 RP-18e (5 μm) 250 × 4.0 mm column connected to 100 CN 4.0 × 4.0 mm guard column on a quaternary HPLC system and run time was 53 min. Linearity of the peak areas for different concentrations ranging from 2.5 to 100 pmol/μL of individual amino acids was determined. A good linearity (R ² > 0.998) was achieved in the standard mixture for each amino acid. Recovery of amino acids incorporated at the time of derivatization ranged from 95 to 106 %. Using this method we have established the normative data of amino acids in plasma, the profile being comparable to the range reported in literature and identified cases of classical homocystinuria, cobalamin defect/deficiency, non-ketotic hyperglycinemia, hyperprolinemia, ketotic hyperglycinemia, urea cycle defect and maple syrup urine disease.     

Molecular mapping of stripe rust resistance gene YrSN104 in Chinese wheat line Shaannong 104

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a serious yield-limiting factor for wheat production worldwide. The objective of this study was to identify and map a stripe rust resistance gene in wheat line Shaannong 104 using SSR markers. F(1) , F(2) and F(3) populations from Shaannong 104/Mingxian 169 were inoculated with Chinese Pst race CYR32 in a greenhouse. Shaannong 104 carried a single dominant gene, YrSN104. Six potential polymorphic SSR markers identified in bulk segregant analysis were used to genotype F(2) and F(3) families. YrSN104 was closely linked with all six SSR markers on chromosome 1BS with genetic distances of 2.0 cM (Xgwm18, Xgwm273, Xbarc187), 2.6 cM (Xgwm11, Xbarc137) and 5.9 cM (Xbarc240). Pedigree analysis, pathogenicity tests using 26 Pst races, haplotyping of associated markers on isogenic lines carrying known stripe rust resistance genes, and associations with markers suggested that YrSN104 was a new resistance gene or an allele at the Yr24/Yr26 locus on chromosome 1BS. Deployment of YrSN104 singly or in combination to elite genotypes could play an effective role to lessen yield losses caused by stripe rust.     

Feasible Bioremediation through Arbuscular Mycorrhizal Fungi Imparting Heavy Metal Tolerance: A Retrospective

Bioremediation is an integrated management of a polluted ecosystem where different organisms are employed to catalyze the natural processes that decontaminate the environment. The potential role of bioremediation, particularly higher terrestrial plants (phytoremediation) research in the remediation of metal-polluted sites, has been the focus of much research in recent years. Arbuscular mycorrhizal fungi are soil microorganisms that establish mutual symbiosis with the majority of higher plants, providing direct links between fungi and roots. This paper reviews the incidence of arbuscular mycorrhizal fungi in metal polluted sites, their role in imparting metal tolerance to plants, the factors affecting arbuscular mycorrhizal fungi in metal polluted sites, and their mechanism of heavy metal tolerance. Particular attention is given to the current methodologies and challenges in this field.     

Manipulation of Ethylene Synthesis in Roots Through Bacterial ACC Deaminase for Improving Nodulation in Legumes

Symbiotic association between rhizobia and legumes results in the development of unique structures on roots, called nodules. Nodulation is a very complex process involving a variety of genes that control NOD factors (bacterial signaling molecules), which are essential for the establishment, maintenance and regulation of this process and development of root nodules. Ethylene is an established potent plant hormone that is also known for its negative role in nodulation. Ethylene is produced endogenously in all plant tissues, particularly in response to both biotic and abiotic stresses. Exogenous application of ethylene and ethylene-releasing compounds are known to inhibit the formation and functioning of nodules. While inhibitors of ethylene synthesis or its physiological action enhance nodulation in legumes, some rhizobial strains also nodulate the host plant intensively, most likely by lowering endogenous ethylene levels in roots through their 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity. Co-inoculation with ACC deaminase containing plant growth promoting rhizobacteria plus rhizobia has been shown to further promote nodulation compared to rhizobia alone. Transgenic rhizobia or legume plants with expression of bacterial ACC deaminase could be another viable option to alleviate the negative effects of ethylene on nodulation. Several studies have well documented the role of ethylene and bacterial ACC deaminase in development of nodules on legume roots and will be the primary focus of this critical review.     

Potassium transport in developing fleshy fruits: the grapevine inward K+ channel VvK1.2 is activated by CIPK–CBL complexes and induced in ripening berry flesh cells

The grape berry provides a model for investigating the physiology of non‐climacteric fruits. Increased K⁺ accumulation in the berry has a strong negative impact on fruit acidity (and quality). In maturing berries, we identified a K⁺ channel from the Shaker family, VvK1.2, and two CBL‐interacting protein kinase (CIPK)/calcineurin B‐like calcium sensor (CBL) pairs, VvCIPK04–VvCBL01 and VvCIPK03–VvCBL02, that may control the activity of this channel. VvCBL01 and VvCIPK04 are homologues of Arabidopsis AtCBL1 and AtCIPK23, respectively, which form a complex that controls the activity of the Shaker K⁺ channel AKT1 in Arabidopsis roots. VvK1.2 remained electrically silent when expressed alone in Xenopus oocytes, but gave rise to K⁺ currents when co‐expressed with the pairs VvCIPK03–VvCBL02 or VvCIPK04–VvCBL01, the second pair inducing much larger currents than the first one. Other tested CIPK–CBL pairs expressed in maturing berries were found to be unable to activate VvK1.2. When activated by its CIPK–CBL partners, VvK1.2 acts as a voltage‐gated inwardly rectifying K⁺ channel that is activated at voltages more negative than –100 mV and is stimulated upon external acidification. This channel is specifically expressed in the berry, where it displays a very strong induction at veraison (the inception of ripening) in flesh cells, phloem tissues and perivascular cells surrounding vascular bundles. Its expression in these tissues is further greatly increased upon mild drought stress. VvK1.2 is thus likely to mediate rapid K⁺ transport in the berry and to contribute to the extensive re‐organization of the translocation pathways and transport mechanisms that occurs at veraison.     

IFNγ Signaling Endows DCs with the Capacity to Control Type I Inflammation during Parasitic Infection through Promoting T-bet+ Regulatory T Cells

IFNγ signaling drives dendritic cells (DCs) to promote type I T cell (Th1) immunity. Here, we show that activation of DCs by IFNγ is equally crucial for the differentiation of a population of T-bet+ regulatory T (Treg) cells specialized to inhibit Th1 immune responses. Conditional deletion of IFNγ receptor in DCs but not in Treg cells resulted in a severe defect in this specific Treg cell subset, leading to exacerbated immune pathology during parasitic infections. Mechanistically, IFNγ-unresponsive DCs failed to produce sufficient amount of IL-27, a cytokine required for optimal T-bet induction in Treg cells. Thus, IFNγ signalling endows DCs with the ability to efficiently control a specific type of T cell immunity through promoting a corresponding Treg cell population.