" Arabidopsis Thaliana " response to insect feeding : new components controlling defense gene expression and plant resistance

Abstract: Plants cannot run away to escape attacking herbivores, but they defend themselves by producing anti-digestive proteins and toxic compounds (for example glucosinolates). The first goal of this thesis was to study changes in gene expression after insect attack using microarrays. The responses of Arabidopsis thaliana to feeding by the specialist Pieris rapae and the generalist Spodoptera liffora is were compared. We found that the transcript profiles after feeding by the two chewing insects were remarkably similar, although the generalist induced a slightly stronger response. The second goal was to evaluate the implication of the four signals jasmonic acid (JA), salicylic acid (SA), ethylene (ET), and abscisic acid (ABA) in the control of insect-regulated gene expression. Using signaling mutants, we observed that JA was the predominant signal and that ABA modulated defense gene expression. In contrast, SA and ET appeared to control slightly gene expression, but only after feeding by S. litforalis. The third goal was to establish whether plant responses are really effective against insects. In accordance with the transcript profile, both insects were affected by the JA-dependent defenses, as they performed better on the JA-insensitive mutant. S. littoralis also performed better on ABA-deficient mutants, providing evidence for the role of ABA in defense against insects. When testing indole or aliphatic glucosinolate deficient mutants, we found that they were also more susceptible to insect feeding, providing some of the first genetic evidence for the defensive role of glucosinolates in planta. Finally, a glutathione-deficient mutant, pad2-1, was also more susceptible to insect feeding and we could attribute this phenotype to a lowered accumulation of the major indole glucosinolate. In this thesis, we provide a comprehensive list of insect-regulated genes, including many transcription factors that constitute interesting candidate genes for the further study of insect-induced expression changes. Understanding how the plant responses to insects are regulated will provide tools for a better management of insect pest in the field. Résumé: Les plantes ne peuvent s'échapper pour fuir les insectes qui les attaquent, mais elles se défendent en produisant des protéines anti-digestives et des composés toxiques (par exemple des glucosinolates). Le premier but de cette thèse était d'étudier les changements de l'expression génétique lors d'attaque par des insectes en utilisant des puces à ADN. Nous avons comparé la réponse d'Arabidopsis thaliana à deux espèces d'insectes avec des habitudes alimentaires différentes : le spécialiste Pieris rapae et le généraliste Spodoptera littoralis. Nous avons trouvé que les profils de transcription après l'attaque par les deux insectes sont remarquablement similaires, bien que le généraliste induise une réponse légèrement plus forte. Le deuxième but était de déterminer l'implication de quatre signaux dans le contrôle de la réponse :l'acide jasmonique (JA), l'acide salicylique (SA), l'éthylène (ET), et l'acide abscissique (ABA). En utilisant de mutants de signalisation, nous avons montré que l'acide jasmonique était le signal prédominant et que l'acide abscissique modulait l'expression génétique. D'autre part, l'acide salicylique et l'éthylène contrôlent à un degré moindre l'expression génétique, mais seulement après l'attaque par S. littoralís. Le troisième but était d'établir si les réponses des plantes sont efficaces contre les insectes. En accord avec le profil de transcription, les deux espèces d'insectes se sont mieux développées sur un mutant insensible au JA, indiquant que les défenses contrôlées par ce signal sont cruciales pour la plante. De plus, les larves de S. littorales se sont mieux développées sur des mutants déficients en ABA, ce qui fournit une preuve du rôle de l'acide abscissique dans la défense contre les insectes. En testant des mutants déficients en glucosinolates de type indole ou aliphatique, nous avons trouvé qu'ils étaient plus sensibles aux insectes, démontrant ainsi le rôle défensif des glucosinolates in planta. Finalement, le mutant déficient en glutathion pad2-1 était aussi plus sensible à l'attaque des insectes, et nous avons pu attribuer ce phénotype à une plus faible augmentation d'un indole glucosinolate dans ce mutant. Dans cette thèse, nous avons mis en évidence un nombre important de gènes contrôlés par les insectes, comprenant de nombreux facteurs de transcription qui constituent des candidats intéressants pour`étudier plus en détail les changements d'expression génétique induits par les insectes. Une meilleure compréhension de la réponse des plantes contre l'attaque des insectes devrait nous permettre de développer de nouvelles stratégies pour mieux gérer les ravageurs des cultures.

Pédiatrie. 1. Comment favoriser le développement de l'oralité en néonatologie [Pediatrics. How can we improve oral feeding in the neonatal intensive care unit?].

Preterm or sick neonates are frequently hampered in establishing a safe and efficient oral feeding. This can delay hospital discharge and impact on parent-child bonding, growth or neurodevelopment. Recent researches identified a pattern of interventions that could allow to reduce these troubles and to shorten hospital stays.

Traitement de l'asthme et de la rhinite durant la grossesse et l'allaitement [Treatment of asthma and rhinitis during pregnancy and breast feeding]

Inhaled therapies are preferred to systemic ones during pregnancy and breast feeding. A real paradox exists however between the necessity to ensure an optimal treatment for pregnant women with asthma, in order to prevent fetal hypoxia, and the precaution linked to any drug prescription during pregnancy. Thus, the use of topical corticosteroids remains the first choice for asthma as well as rhinitis. Inhaled beta2-agonists are also recommended. Systemic corticosteroids may however be prescribed without hesitation when their use is required for asthma treatment. It is also interesting to note that oral second-generation antihistamines are currently allowed during pregnancy and breast feeding. This type of antihistamines is indeed to be preferred to first-generation ones that generate more side-effects and generally are thus not to be prescribed during breast feeding.

Association between protein feeding and reproductive efficiency in the dairy cow : specific emphasis on protein feeding in Finland

Selostus: Lypsylehmien valkuaisruokinnan ja hedelmällisyyden yhteys: kirjallisuustutkimus valkuaisruokinnan vaikutuksista Suomen olosuhteissa

Effect of feeding level and diet type on the performance of crossbred suckler cows and their calves

Selostus: Ureoidun oljen soveltuvuus risteytysemojen talviruokintaan kahdella eri ruokintatasolla

Feeding levels during the growing phase affect the production of primiparous Finnish Landrace ewes

Selostus: Ruokinnan voimakkuuden vaikutus siitosuuhikaritsan tuotantoon

The Limits of Issue Ownership Dynamics : The Constraining Effect of Party Preference

Issue ownership theory argues that when a voter considers a party to be the most competent amongst others to deal with an issue (that is, the party "owns" the issue), chances are the voter will vote for that party. Recent work has shown that perceptions of issue ownership are dynamic: they are affected by the media coverage of party messages. However, based on the broad literature on partisan bias, we predict that parties' efforts to change issue ownership perceptions will have a difficult time breaching the perceptual screen created by a voter's party preference. Using two separate experiments with a similar design we show that the effect of partisan issue messages on issue competence is moderated by party preference. The effect of issue messages is reinforced when people already like a party, and blocked when people dislike a party.

Effects of season, sex and body size on the feeding ecology of turtle-headed seasnakes (Emydocephalus annulatus) on IndoPacific inshore coral reefs

In terrestrial snakes, many cases of intraspecific shifts in dietary habits as a function of predator sex and body size are driven by gape-limitation - and hence, are most common in species that feed on relatively large prey, and exhibit a wide body-size range. Our data on seasnakes reveal an alternative mechanism for intraspecific niche partitioning, based on sex-specific seasonal anorexia induced by reproductive activities. Turtle-headed seasnakes (Emydocephalus annulatus) on coral reefs in the New Caledonian Lagoon feed entirely on the eggs of demersal-spawning fishes. DNA sequence data (cytochrome b gene) on eggs that we palpated from stomachs of 37 snakes showed that despite this ontogenetic-stage specialization, the prey come from a taxonomically diverse array of species including damselfish (41% of samples, at least 5 species), blennies (41%, 4 species) and gobies (19%, 5 species). The composition of snake diets shifted seasonally (with damselfish dominating in winter but not summer), presumably reflecting seasonality of fish reproduction. That seasonal shift affects male and female snakes differently, because reproduction is incompatible with foraging. Adult female seasnakes ceased feeding when they became heavily distended with developing embryos in late summer, and males ceased feeding while they were mate-searching in winter. The sex divergence in foraging habits may be amplified by sexual size dimorphism; females grow larger than males, and larger snakes (of both sexes) feed more on damselfish (which often lay their eggs in exposed sites) than on blennies and gobies (whose eggs are hidden within narrow crevices). Specific features of reproductive biology of coral-reef fish (seasonality and nest type) have generated intraspecific niche partitioning in these seasnakes, by mechanisms different from those that apply to terrestrial snakes.

Flight, feeding and reproductive behavior of Phyllophaga cuyabana (Moser) (Coleoptera: Melolonthidae) adults

Phyllophaga cuyabana is a univoltine species and its development occurs completely underground. Its control by conventional methods, such as chemical and biological insecticides, is difficult, so it is important to understand its dispersion, reproduction, and population behavior in order to determine best pest management strategies. The objective of this work was to study the behavior of adults of P. cuyabana. This study was carried out in the laboratory, greenhouse and field sites in Paraná State, Brazil (24º25' S and 52º48' W), during four seasons. The results obtained demonstrate that: a) P. cuyabana adults have a synchronized short-flight period when mating and reproduction occurs; b) adults tend to aggregate in specific sites for mating; c) the majority of adults left the soil on alternate nights; d) the choice of mating and oviposition sites was made by females before copulation, since after copulation adults did not fly from or bury themselves at nearby locations; e) females that fed on leaves after mating, oviposited more eggs than females that had not fed;f) plant species such as sunflower (Helianthus annuus) and the Crotalaria juncea are important food sources for adults.

Insulin induces long-term depression of ventral tegmental area dopamine neurons via endocannabinoids.

The prevalence of obesity has markedly increased over the past few decades. Exploration of how hunger and satiety signals influence the reward system can help us understand non-homeostatic feeding. Insulin may act in the ventral tegmental area (VTA), a critical site for reward-seeking behavior, to suppress feeding. However, the neural mechanisms underlying insulin effects in the VTA remain unknown. We demonstrate that insulin, a circulating catabolic peptide that inhibits feeding, can induce long-term depression (LTD) of mouse excitatory synapses onto VTA dopamine neurons. This effect requires endocannabinoid-mediated presynaptic inhibition of glutamate release. Furthermore, after a sweetened high-fat meal, which elevates endogenous insulin, insulin-induced LTD is occluded. Finally, insulin in the VTA reduces food anticipatory behavior in mice and conditioned place preference for food in rats. Taken together, these results suggest that insulin in the VTA suppresses excitatory synaptic transmission and reduces anticipatory activity and preference for food-related cues.

Is use of nifurtimox for the treatment of Chagas disease compatible with breast feeding? A population pharmacokinetics analysis.

Introduction Women with Chagas disease receiving treatment with nifurtimox are discouraged from breast feeding. Many patients who would receive treatment with nifurtimox live in extreme poverty, have limited access to resources such as clean water and baby formula and may not have safe alternatives to breast milk. Aim We aimed to estimate, using limited available pharmacokinetics data, potential infant exposure to nifurtimox through breast milk. Methods Original nifurtimox plasma concentrations were obtained from published studies. Pharmacokinetic parameters were estimated using non-linear mixed-effect modelling with NONMEM V.VI. A total of 1000 nifurtimox plasma-concentration profiles were simulated and used to calculate the amount of drug that an infant would be exposed to, if breast fed 150 ml/kg/day. Results Breast milk concentrations on the basis of peak plasma levels (1361 ng/ml) and milk-plasma ratio were estimated. We calculated infant nifurtimox exposure of a breastfed infant of a mother treated with this drug to be below 10% of the maternal weight-adjusted dose, even if milk-plasma ratio were overestimated. Simulation led to similar estimates. Discussion Risk for significant infant exposure to nifurtimox through breast milk seems small and below the level of exposure of infants with Chagas disease receiving nifurtimox treatment. This potential degree of exposure may not justify discontinuation of breast feeding.

Feeding of nauplii, copepodites and adults of Calanipeda aquaedulcis (Calanoida) in Mediterranean salt marshes

Feeding of the different developmental stages of Calanipeda aquaedulcis on natural particles (bacterio-, phyto- and microzooplankton) was measured in a Mediterranean salt marsh (Empordà wetlands, NE Iberian Peninsula). Bottle incubations were performed in the field both in autumn and spring. The results showed differences in the diet of the different developmental stages due to both prey type and size. In general, the size of the ingested prey increased with increasing size of the C. aquaedulcis stage. While C. aquaedulcis adults had high ingestion rates and selection coefficients for large prey (micro- and nanoplankton), nauplii preferentially consumed smaller prey items (picoplankton). Copepodites showed the widest prey size range, including pico-, nano- and microplankton. Nevertheless, the lower size limit for particle capture was similar for all stages, i.e. between 1.7 and 2.1 μm. Omnivory was observed in all stages of C. aquaedulcis. Heterotrophic prey (picoplankton, dinoflagellates and ciliates) were the most ingested items. The ability to partition the available food among the different developmental stages could represent an advantage in times of ood scarcity because it may reduce intraspecific competition. This may explain how C. aquaedulcis is able to predominate in the zooplankton community for several weeks during spring and summer ven in situations of low food availability

Feeding and arrestment responses of Diabrotica speciosa to cucurbitacin-content formulations

The objective of this work was to evaluate arrestant and stimulant feeding effects on Diabrotica speciosa (Ger.), using cucurbitacin-content starch-based formulations prepared with varying starch sources, and adding potassium lignate. In a glass slide assay, the wash off resistance of formulations was compared. Potassium lignate did not improve wash off resistance. Lagenaria vulgaris L. powder, in which cucurbitacin B concentration was determined as 0.28%, was added to the most adhesive formulation. The resultant material was used in a two-choice assay in which leaves of common bean, Phaseolus vulgaris L., treated with concentrations of 2.5%, 5%, 10%, 15% and 20% were offered to insects together with untreated control leaves. Greater number of insects and leaves consumed were found on leaves treated with cucurbitacin-content formulation (2.5%, 5% - greatest response -, 10% and 15% concentrations) than on untreated control leaves. The concentration, in which responses were higher, was sprayed in a bean field at 1,000, 1,900 and 3,000 g ha-1. Greater number of beetles was found in plots treated with the highest dosage, 3 and 6 days after spraying. Ten days after spraying, no significant differences were found among dosages, probably due to washoff of the bait.

Diverging Cave- and River-Dwelling Newts Exert the Same Mate Preference in their Native Light Conditions

When colonizing a new habitat, populations must adapt their sexual behaviour to new ecological constraints. Because caves display drastically different conditions from surface habitats and cave animals are deprived from visual information, hypogean populations are expected to have modified their mate preference and signalling behaviour after cave colonization. Here, we experimentally examined the female preference and the sexual behaviour of brook newts Calotriton asper from different cave and river populations, either in light or in darkness. Our results suggest that females prefer large individuals in both hypogean and epigean populations, but that this preference is only expressed in the light conditions of their native habitat. Hence, some mate choice criteria would be maintained across genetically divergent populations and throughout dissimilar habitats. However, this sexual behaviour is likely to be expressed via a different sensory pathway in the different habitats, suggesting that a sensory shift has occurred in cave populations, enabling animals to communicate through a non-visual channel.