Mycorrhiza-Tree-Herbivore Interactions: Alterations in Poplar Metabolome and Volatilome.

Plants are continuously interacting with other organisms to optimize their performance in a changing environment. Mycorrhization is known to affect the plant growth and nutrient status, but it also can lead to adjusted plant defense and alter interactions with other trophic levels. Here, we studied the effect of -mycorrhization on the poplar ( x ) metabolome and volatilome on trees with and without a poplar leaf beetle () infestation.

Mycorrhiza-Triggered Transcriptomic and Metabolomic Networks Impinge on Herbivore Fitness.

Symbioses between plants and mycorrhizal fungi are ubiquitous in ecosystems and strengthen the plants' defense against aboveground herbivores. Here, we studied the underlying regulatory networks and biochemical mechanisms in leaves induced by ectomycorrhizae that modify herbivore interactions. Feeding damage and oviposition by the widespread poplar leaf beetle were reduced on the ectomycorrhizal hybrid poplar × Integration of transcriptomics, metabolomics, and volatile emission patterns via mass difference networks demonstrated changes in nitrogen allocation in the leaves of mycorrhizal poplars, down-regulation of phenolic pathways, and up-regulation of defensive systems, including protease inhibitors, chitinases, and aldoxime biosynthesis.

Isoprene emission by poplar is not important for the feeding behaviour of poplar leaf beetles.

Background: Chrysomela populi (poplar leaf beetle) is a common herbivore in poplar plantations whose infestation causes major economic losses. Because plant volatiles act as infochemicals, we tested whether isoprene, the main volatile organic compound (VOC) produced by poplars (Populus x canescens), affects the performance of C. populi employing isoprene emitting (IE) and transgenic isoprene non-emitting (NE) plants.

UV-B mediated metabolic rearrangements in poplar revealed by non-targeted metabolomics.

Plants have to cope with various abiotic stresses including UV-B radiation (280-315 nm). UV-B radiation is perceived by a photoreceptor, triggers morphological responses and primes plant defence mechanisms such as antioxidant levels, photoreapir or accumulation of UV-B screening pigments. As poplar is an important model system for trees, we elucidated the influence of UV-B on overall metabolite patterns in poplar leaves grown under high UV-B radiation.

Angiotensin II receptor blockade in TGR(mREN2)27: effects of renin-angiotensin-system gene expression and cardiovascular functions.

Objective: To study the effect of angiotensin II receptor AT1 blockade on blood pressure, gene expression and pathomorphology of transgenic rats harbouring the mouse Ren-2 gene [TGR(mREN2)27], that develop fulminant hypertension while exhibiting suppressed components of the circulating renin-angiotensin system.

Design: TGR(mREN2)27 were treated orally with the newly developed AT1-specific angiotensin receptor antagonist Telmisartan, 4'-[(1,4'-dimethyl-2'-propyl[2,6'-bi-1H-benzimidazol]-1'-yl) methyl]-[1,1'-biphenyl]-2-carboxylic acid, in three doses (0.1, 1 and 3 mg/kg body weight) for 9 weeks.

High blood pressure in transgenic mice carrying the rat angiotensinogen gene.

Transgenic mice were generated by injecting the entire rat angiotensinogen gene into the germline of NMRI mice. The resulting transgenic animals were characterized with respect to hemodynamics, parameters of the renin angiotension system, and expression of the transgene. The transgenic line TGM(rAOGEN)123 developed hypertension with a mean arterial blood pressure of 158 mmHg in males and 132 mmHg in females.

Basic methodology in the molecular characterization of genes.

Purpose: During the past two decades, molecular biology techniques have had an increasing impact upon hypertension research. This article will thus review the basic methodology in this field.

Contents: Protocols are described for the establishment of a genomic library and its use for the cloning of specific genes, as well as methods for the detection and sequencing of DNA.

Glucocorticoid- and estrogen-responsive elements in the 5'-flanking region of the rat angiotensinogen gene.

We investigated the 5'-flanking region of the rat angiotensinogen gene to define the DNA elements conferring inducibility by glucocorticoids and estrogens. Two putative glucocorticoid-responsive elements (GREs) based on sequence comparison were identified. Here we report the functional importance of these sequences.

Liver-specific gene expression: A-activator-binding site, a promoter module present in vitellogenin and acute-phase genes.

The A2 vitellogenin gene of Xenopus laevis, which is expressed liver specifically, contains an A-activator-binding site (AABS) that mediates high in vitro transcriptional activity in rat liver nuclear extracts. Footprint experiments with DNase I and gel retardation assays revealed the binding of several proteins to AABS. Using binding sites of known DNA-binding proteins as competitors in the gel retardation assay, we found that the transcription factor C/EBP and/or one of its "iso-binders" as well as LFB1/HNF1 bound AABS.

BAP, a rat liver protein that activates transcription through a promoter element with similarity to the USF/MLTF binding site.

The vitellogenin genes of Xenopus are liver-specifically expressed. An in vitro transcription system derived from rat liver nuclei allowed us to define the cis-element BABS (B-activator binding site) in the promoter of the B1 vitellogenin gene. An oligonucleotide encompassing the region from -53 to -44 linked to a TATA box is sufficient for a tenfold increase of the transcriptional activity.

Transcription factors different from the estrogen receptor stimulate in vitro transcription from promoters containing estrogen response elements.

The estrogen response element (ERE) directly linked to a TATA box induces CAT activity in a hormone-dependent manner in Fe 33 cells, the rat hepatoma cell line FTO-2B, stably transfected with the human estrogen receptor (ER). The same promoter construct mediates the stimulation of in vitro transcription. This stimulation is dependent on the presence of the ERE.

Liver cell specific gene transcription in vitro: the promoter elements HP1 and TATA box are necessary and sufficient to generate a liver-specific promoter.

The hepatocyte-specific promoter element HP1, which is present in several genes specifically expressed in the liver, is active in an in vitro transcription system. The liver-specificity is retained in the in vitro system, as the activity is found in extracts of rat liver or hepatoma cells but is absent in an L-cell extract. Mutational analysis identifies HP1 as a 13 bp element: Two point mutations abolish the function of HP1.

Synergism of closely adjacent estrogen-responsive elements increases their regulatory potential.

Recent gene transfer experiments have shown that an estrogen-responsive DNA element (ERE) GGTCANNNTGACC mediates the estrogen inducibility of the Xenopus laevis vitellogenin A1 and A2 genes as well as the chicken vitellogenin II gene. We report here on experiments that explain the estrogen regulation of the Xenopus vitellogenin B1 and B2 genes. In these genes, two ERE homologues, which have only low, if any, regulatory capacity on their own, act synergistically to achieve high estrogen inducibility.

In-vitro synthesis of phycobiliproteids and ribulose-1,5-bisphosphate carboxylase by non-poly-adenylated-RNA of Cyanidium caldarium and Porphyridium aerugineum.

Polyadenylated and nonpolyadenylated mRNa from the red algae Cyanidium caldarium Geitler and Porphyridium aerugineum Geitler were translated in a cell-free system. The α-and β-subunits of phycocyanin and allophycocyanin and also both subunits of ribulose-1,5-bisphosphate carboxylase-oxygenase (RuBPCase) were identified with the help of specific antibodies as translation products of non-polyadenylated mRNA. Both subunits of RuBPCase were synthesized with molecular weights in the range of the mature forms.