The serine-rich N-terminal region of Arabidopsis phytochrome A is required for protein stability.

Deletion or substitution of the serine-rich N-terminal stretch of grass phytochrome A (phyA) has repeatedly been shown to yield a hyperactive photoreceptor when expressed under the control of a constitutive promoter in transgenic tobacco or Arabidopsis seedlings retaining their native phyA. These observations have lead to the proposal that the serine-rich region is involved in negative regulation of phyA signaling. To re-evaluate this conclusion in a more physiological context we produced transgenic Arabidopsis seedlings of the phyA-null background expressing Arabidopsis PHYA deleted in the sequence corresponding to amino acids 6-12, under the control of the native PHYA promoter. Compared to the transgenic seedlings expressing wild-type phyA, the seedlings bearing the mutated phyA showed normal responses to pulses of far-red (FR) light and impaired responses to continuous FR light. In yeast two-hybrid experiments, deleted phyA interacted normally with FHY1 and FHL, which are required for phyA accumulation in the nucleus. Immunoblot analysis showed reduced stability of deleted phyA under continuous red or FR light. The reduced physiological activity can therefore be accounted for by the enhanced destruction of the mutated phyA. These findings do not support the involvement of the serine-rich region in negative regulation but they are consistent with a recent report suggesting that phyA turnover is regulated by phosphorylation.

The heat shock response in moss plants is regulated by specific calcium-permeable channels in the plasma membrane.

Land plants are prone to strong thermal variations and must therefore sense early moderate temperature increments to induce appropriate cellular defenses, such as molecular chaperones, in anticipation of upcoming noxious temperatures. To investigate how plants perceive mild changes in ambient temperature, we monitored in recombinant lines of the moss Physcomitrella patens the activation of a heat-inducible promoter, the integrity of a thermolabile enzyme, and the fluctuations of cytoplasmic calcium. Mild temperature increments, or isothermal treatments with membrane fluidizers or Hsp90 inhibitors, induced a heat shock response (HSR) that critically depended on a preceding Ca(2+) transient through the plasma membrane. Electrophysiological experiments revealed the presence of a Ca(2+)-permeable channel in the plasma membrane that is transiently activated by mild temperature increments or chemical perturbations of membrane fluidity. The amplitude of the Ca(2+) influx during the first minutes of a temperature stress modulated the intensity of the HSR, and Ca(2+) channel blockers prevented HSR and the onset of thermotolerance. Our data suggest that early sensing of mild temperature increments occurs at the plasma membrane of plant cells independently from cytosolic protein unfolding. The heat signal is translated into an effective HSR by way of a specific membrane-regulated Ca(2+) influx, leading to thermotolerance.

The fixation of locally beneficial alleles in a metapopulation.

Extinction, recolonization, and local adaptation are common in natural spatially structured populations. Understanding their effect upon genetic variation is important for systems such as genetically modified organism management or avoidance of drug resistance. Theoretical studies on the effect of extinction and recolonization upon genetic variance started appearing in the 1970s, but the role of local adaptation still has no good theoretical basis. Here we develop a model of a haploid species in a metapopulation in which a locally adapted beneficial allele is introduced. We study the effect of different spatial patterns of local adaptation, and different metapopulation dynamics, upon the fixation probability of the beneficial allele. Controlling for the average selection pressure, we find that a small area of positive selection can significantly increase the global probability of fixation. However, local adaptation becomes less important as extinction rate increases. Deme extinction and recolonization have a spatial smoothing effect that effectively reduces spatial variation in fitness.

No impact of Bt soybean that express Cry1Ac protein on biological traits of Euschistus heros (Hemiptera, Pentatomidae) and its egg parasitoid Telenomus podisi (Hymenoptera, Platygastridae)

No impact of Bt soybean that express Cry1Ac protein on biological traits of Euschistus heros (Hemiptera, Pentatomidae) and its egg parasitoid Telenomus podisi (Hymenoptera, Platygastridae). Biological traits of the stink bug Euschistus heros and its main biological control agent Telenomus podisi were evaluated under controlled environmental conditions (25 ± 2ºC; 60 ± 10% RH; and 14/10 h photoperiod) by placing first instar nymphs into Petri dishes with pods originating from two soybean isolines (Bt-soybean MON 87701 × MON 89788, which expresses the Cry1Ac protein, and its near non-Bt isoline A5547) where they remained until the adult stage. Due to gregarious behavior exhibited by first instar nymphs, they were individualized only when at the second instar. Adults were separated by sex and weighed, and pronotum width of each individual was subsequently measured. They were placed into plastic boxes containing soybean grains of the same soybean isoline as food source. Egg viability and female fecundity were assessed in adult individuals. Adult females of T. podisi (up to 24h old) were placed with eggs of E. heros from mothers reared on both soybean isolines. Nymphal development time, insect weight, pronotum width, sex ratio, female fecundity, and egg viability (% emergence) of Euschistus heros did not differ between treatments. Eggto-adult development time, female longevity, sex ratio, and percentage of parasitized eggs were not impacted by the Bt-soybean (expressing Cry1Ac protein). Results indicate that the Bt-soybean, MON 87701 × MON 89788, has no direct significant impact on the two studied species.

Does Bt maize cultivation affect the non-target insect community in the agro ecosystem?

ABSTRACT The cultivation of genetically modified crops in Brazil has led to the need to assess the impacts of this technology on non-target species. Under field conditions, the potential effect on insect biodiversity was evaluated by comparing a homogeneous corn field with conventional and transgenic maize, expressing different Bt proteins in seven counties of Minas Gerais, Brazil. The richness pattern of non-target insect species, secondary pests and natural enemies were observed. The results do not support the hypothesis that Bt protein affects insect biodiversity. The richness and diversity data of insects studied were dependent on the location and other factors, such as the use of insecticides, which may be a major factor where they are used.

Construction of Pseudomonas strains with improved biocontrol activity

Selected strains of fluorescent pseudomonads suppress various plant diseases caused by soil-borne pathogenic fungi, by a blend of several mechanisms including aggressive root colonization, antibiosis, competition for nutrients, induction of resistance in the plant, and enzymatic attack of the pathogen. These traits are amenable to genetic analysis and, therefore, to modification by genetic engineering. Biocontrol activities of Pseudomonas spp. have been enhanced in two ways: (i) by overexpression of traits known to involved in diseaese suppression, and (ii) by introduction of additional beneficial traits into strains having basal biocontrol activities. Under experimental conditions in microcosms, a number of genetically modified Pseudomonas strains have given promising results. It remains to be seen whether such strains will be superior to the best naturally occurring strains, applied singly or in combination, under greenhouse and field conditions.

The Social Value of Being Ambivalent: Self-Presentational Concerns in the Expression of Attitudinal Ambivalence

We tested whether individuals can exert control over the expression of attitudinal ambivalence and if this control is exerted with self-presentational concerns. Using the self-presentation paradigm, participants reported more ambivalence about Genetically Modified Organisms ("GMO") in a standard and a self-enhancement (present yourself positively) conditions than in a self-depreciation (present yourself negatively) condition, on both felt (Experiments 1a and 2a) and potential ambivalence, in its cognitive (Experiments 1b and 2b) and affective components (Experiments 1b and 2c). The role of ambivalent attitudes in conveying a positive social value was confirmed by the fact that the above effect was found on a controversial attitude object (GMOs) but the opposite appeared on a non-controversial one (e.g. tooth brushing, a truism; Experiment 3). Such a reversal was obtained by directly manipulating the perception of controversy on GMOs (Experiment 4). Attitudinal ambivalence may thus serve an adaptive function, i.e. achieving a positive social value.

Production of polyesters in transgenic plants.

Polyhydroxyalkanoates (PHAs) are bacterial polyesters having the properties of biodegradable thermoplastics and elastomers. Synthesis of PHAs has been demonstrated in transgenic plants. Both polyhydroxybutyrate and the co-polymer poly(hydroxybutyrate-co-hydroxyvalerate) have been synthesized in the plastids of Arabidopsis thaliana and Brassica napus. Furthermore, a range of medium-chain-length PHAs has also been produced in plant peroxisomes. Development of agricultural crops to produce PHA on a large scale and at low cost will be a challenging task requiring a coordinated and stable expression of several genes. Novel extraction methods designed to maximize the use of harvested plants for PHA, oil, carbohydrate, and feed production will be needed. In addition to their use as plastics, PHAs can also be used to modify fiber properties in plants such as cotton. Furthermore, PHA can be exploited as a novel tool to study the carbon flux through various metabolic pathways, such as the fatty acid beta-oxidation cycle.

Essais en plein champ avec du blé génétiquement modifié résistant à l'oïdium

Les bénéfices et les risques environnementaux du blé de printemps génétiquement modifié (GM), plus résistant à l'oïdium, ont été étudiés sur deux sites en plein champ de 2008 à 2010, dans le cadre d'un réseau de groupes de recherche suisses. Les lignées de blé GM, possédant une résistance spécifique à l'oïdium et aux maladies fongiques en général, ont été comparées à des variétés de blé commercialisées, à des lignées témoins ainsi qu'à de l'orge et du triticale. Outre la résistance à l'oïdium, l'étude a également porté sur les répercussions sur les insectes et les organismes du sol (bactéries, champignons mycorhiziens, faune du sol) ainsi que sur les croisements fortuits du blé. Plusieurs lignées de blé GM étaient nettement plus résistantes à l'oïdium que les témoins. Aucun impact significatif sur les organismes non-cibles n'a été constaté, sur leur biodiversité ou sur certaines fonctions sélectionnées des écosystèmes. Dans l'ensemble, les différences entre le blé GM et les lignées témoins étaient moindres qu'entre les variétés de blé commerciales ou les autres espèces de céréales. Les cas de croisement fortuits étaient rares et n'ont été trouvés qu'à faible distance des plantes GM de l'essai.

Chloroplastic phosphoadenosine phosphosulfate metabolism regulates basal levels of the prohormone jasmonic acid in Arabidopsis leaves.

Levels of the enzymes that produce wound response mediators have to be controlled tightly in unwounded tissues. The Arabidopsis (Arabidopsis thaliana) fatty acid oxygenation up-regulated8 (fou8) mutant catalyzes high rates of alpha -linolenic acid oxygenation and has higher than wild-type levels of the alpha -linolenic acid-derived wound response mediator jasmonic acid (JA) in undamaged leaves. fou8 produces a null allele in the gene SAL1 (also known as FIERY1 or FRY1). Overexpression of the wild-type gene product had the opposite effect of the null allele, suggesting a regulatory role of SAL1 acting in JA synthesis. The biochemical phenotypes in fou8 were complemented when the yeast (Saccharomyces cerevisiae) sulfur metabolism 3'(2'), 5'-bisphosphate nucleotidase MET22 was targeted to chloroplasts in fou8. The data are consistent with a role of SAL1 in the chloroplast-localized dephosphorylation of 3'-phospho-5'-adenosine phosphosulfate to 5'-adenosine phosphosulfate or in a closely related reaction (e.g. 3',5'-bisphosphate dephosphorylation). Furthermore, the fou8 phenotype was genetically suppressed in a triple mutant (fou8 apk1 apk2) affecting chloroplastic 3'-phospho-5'-adenosine phosphosulfate synthesis. These results show that a nucleotide component of the sulfur futile cycle regulates early steps of JA production and basal JA levels.

Level of accumulation of epoxy fatty acid in Arabidopsis thaliana expressing a linoleic acid delta12-epoxygenase is influenced by the availability of the substrate linoleic acid.

Arabidopsis thaliana (L.) Heynh. expressing the Crepis palaestina (L.) linoleic acid delta12-epoxygenase in its developing seeds typically accumulates low levels of vernolic acid (12,13-epoxy-octadec-cis-9-enoic acid) in comparison to levels found in seeds of the native C. palaestina. In order to determine some of the factors limiting the accumulation of this unusual fatty acid, we have examined the effects of increasing the availability of linoleic acid (9cis, 12cis-octadecadienoic acid), the substrate of the delta12-epoxygenase, on the quantity of epoxy fatty acids accumulating in transgenic A. thaliana. The addition of linoleic acid to liquid cultures of transgenic plants expressing the delta12-epoxygenase under the control of the cauliflower mosaic virus 35S promoter increased the amount of vernolic acid in vegetative tissues by 2.8-fold. In contrast, the addition to these cultures of linoelaidic acid (9trans, 12trans-octadecadienoic acid), which is not a substrate of the delta12-epoxygenase, resulted in a slight decrease in vernolic acid accumulation. Expression of the delta12-epoxygenase under the control of the napin promoter in the A. thaliana triple mutant fad3/fad7-1/fad9, which is deficient in the synthesis of tri-unsaturated fatty acids and has a 60% higher level of linoleic acid than the wild type, was found to increase the average vernolic acid content of the seeds by 55% compared to the expression of the delta12-epoxygenase in a wild-type background. Together, these results reveal that the availability of linoleic acid is an important factor affecting the synthesis of epoxy fatty acid in transgenic plants.

Re-thinking cell cycle regulators: the cross-talk with metabolism.

Analysis of genetically engineered mice deficient in cell cycle regulators, including E2F1, cdk4, and pRB, showed that the major phenotypes are metabolic perturbations. These key cell cycle regulators contribute to lipid synthesis, glucose production, insulin secretion, and glycolytic metabolism. It has been shown that deregulation of these pathways can lead to metabolic perturbations and related metabolic diseases, such as obesity and type II diabetes. The cyclin-cdk-Rb-E2F1 pathway regulates adipogenesis in addition to its well-described roles in cell cycle regulation and cancer. It was also shown that E2F1 directly participates in the regulation of pancreatic growth and function. Similarly, cyclin D3, cdk4, and cdk9 are also adipogenic factors with strong effects on whole organism metabolism. These examples support the emerging notion that cell cycle regulatory proteins also modulate metabolic processes. These cell cycle regulators are activated by insulin and glucose, even in non-proliferating cells. Most importantly, these cell cycle regulators trigger the adaptive metabolic switch that normal and cancer cells require in order to proliferate. These changes include increased lipid synthesis, decreased oxidative metabolism, and increased glycolytic metabolism. In summary, these factors are essential regulators of anabolic biosynthetic processes, blocking at the same time oxidative and catabolic pathways, which is reminiscent of cancer cell metabolism.

Differential effectiveness of microbially induced resistance against herbivorous insects in Arabidopsis.

Rhizobacteria-induced systemic resistance (ISR) and pathogen-induced systemic acquired resistance (SAR) have a broad, yet partly distinct, range of effectiveness against pathogenic microorganisms. Here, we investigated the effectiveness of ISR and SAR in Arabidopsis against the tissue-chewing insects Pieris rapae and Spodoptera exigua. Resistance against insects consists of direct defense, such as the production of toxins and feeding deterrents and indirect defense such as the production of plant volatiles that attract carnivorous enemies of the herbivores. Wind-tunnel experiments revealed that ISR and SAR did not affect herbivore-induced attraction of the parasitic wasp Cotesia rubecula (indirect defense). By contrast, ISR and SAR significantly reduced growth and development of the generalist herbivore S. exigua, although not that of the specialist P. rapae. This enhanced direct defense against S. exigua was associated with potentiated expression of the defense-related genes PDF1.2 and HEL. Expression profiling using a dedicated cDNA microarray revealed four additional, differentially primed genes in microbially induced S. exigua-challenged plants, three of which encode a lipid-transfer protein. Together, these results indicate that microbially induced plants are differentially primed for enhanced insect-responsive gene expression that is associated with increased direct defense against the generalist S. exigua but not against the specialist P. rapae.

Transglutaminase 1-deficient recessive lamellar ichthyosis associated with a LINE-1 insertion in Jack Russell terrier dogs.

BACKGROUND: Congenital, nonepidermolytic cornification disorders phenotypically resembling human autosomal recessive ichthyosis have been described in purebred dog breeds, including Jack Russell terrier (JRT) dogs. One cause of gene mutation important to humans and dogs is transposon insertions. OBJECTIVES: To describe an autosomal recessive, severe nonepidermolytic ichthyosis resembling lamellar ichthyosis (LI) in JRT dogs due to insertion of a long interspersed nucleotide element (LINE-1) in the transglutaminase 1 (TGM1) gene. METHODS: Dogs were evaluated clinically, and skin samples were examined by light and electron microscopy. Phenotypic information and genotyping with a canine microsatellite marker suggested TGM1 to be a candidate gene. Genomic DNA samples and cDNA generated from epidermal RNA were examined. Consequences of the mutation were evaluated by Western blotting, quantitative reverse transcription-polymerase chain reaction (RT-PCR) and enzyme activity from cultured keratinocytes. RESULTS: Affected dogs had generalized severe hyperkeratosis. Histological examination defined laminated to compact hyperkeratosis without epidermolysis; ultrastructurally, cornified envelopes were thin. Affected dogs were homozygous for a 1980-bp insertion within intron 9 of TGM1. The sequence of the insertion was that of a canine LINE-1 element. Quantitative RT-PCR indicated a significant decrease in TGM1 mRNA in affected dogs compared with wild-type. TGM1 protein was markedly decreased on immunoblotting, and membrane-associated enzyme activity was diminished in affected dogs. CONCLUSIONS: Based on morphological and molecular features, this disease is homologous with TGM1-deficient LI in humans, clinically models LI better than the genetically modified mouse and represents its first spontaneous animal model. This is the first reported form of LI due to transposon insertion.

Uncoupling phosphate deficiency from its major effects on growth and transcriptome via PHO1 expression in Arabidopsis.

Inorganic phosphate (Pi) is one of the most limiting nutrients for plant growth in both natural and agricultural contexts. Pi-deficiency leads to a strong decrease in shoot growth, and triggers extensive changes at the developmental, biochemical and gene expression levels that are presumably aimed at improving the acquisition of this nutrient and sustaining growth. The Arabidopsis thaliana PHO1 gene has previously been shown to participate in the transport of Pi from roots to shoots, and the null pho1 mutant has all the hallmarks associated with shoot Pi deficiency. We show here that A. thaliana plants with a reduced expression of PHO1 in roots have shoot growth similar to Pi-sufficient plants, despite leaves being strongly Pi deficient. Furthermore, the gene expression profile normally triggered by Pi deficiency is suppressed in plants with low PHO1 expression. At comparable levels of shoot Pi supply, the wild type reduces shoot growth but maintains adequate shoot vacuolar Pi content, whereas the PHO1 underexpressor maintains maximal growth with strongly depleted Pi reserves. Expression of the Oryza sativa (rice) PHO1 ortholog in the pho1 null mutant also leads to plants that maintain normal growth and suppression of the Pi-deficiency response, despite the low shoot Pi. These data show that it is possible to unlink low shoot Pi content with the responses normally associated with Pi deficiency through the modulation of PHO1 expression or activity. These data also show that reduced shoot growth is not a direct consequence of Pi deficiency, but is more likely to be a result of extensive gene expression reprogramming triggered by Pi deficiency.