Plants and tortoises: mutations in the Arabidopsis jasmonate pathway increase feeding in a vertebrate herbivore.

Photosynthetic tissues, the major food source of many invertebrates and vertebrates, are well defended. Many defence traits in leaves are controlled via the jasmonate signalling pathway in which jasmonate acts as a hormone by binding to a receptor to activate responses that lead to increased resistance to invertebrate folivores. We predicted that mutations in jasmonate synthesis might also increase the vulnerability of leaves to vertebrate folivores and tested this hypothesis using the Eastern Hermann's tortoise (Eurotestudo boettgeri) and an Arabidopsis thaliana (Brassicaceae) allene oxide synthase (aos) mutant unable to synthesize jasmonate. Tortoises preferred the aos mutant over the wild type (WT). Based on these results, we then investigated the effect of mutating jasmonate perception using a segregating population of the recessive A. thaliana jasmonate receptor mutant coronatine insensitive1-1 (coi1-1). Genotyping of these plants after tortoise feeding revealed that the homozygous coi1-1 receptor mutant was consumed more readily than the heterozygous mutant or the WT. Therefore, the plant's ability to synthesize or perceive jasmonate reduces feeding by a vertebrate herbivore. We also tested whether or not tortoise feeding behaviour was influenced by glucosinolates, the principal defence chemicals in Arabidopsis leaves with known roles in defence against many generalist insects. However, in contrast to what has been observed with such insects, leaves in which the levels of these compounds were reduced genetically were consumed at a similar rate to those of the WT.

Energy balance, physical activity, and thermogenic effect of feeding in premature infants.

In order to assess the contribution of the thermogenic effect of feeding and muscular activity to total energy expenditure, nine premature infants were studied for 2 consecutive days during which time repeated measurements of energy expenditure by indirect calorimetry were performed throughout the day, combined with a visual activity score based on body movement. The infants were growing at 16.6 +/- 4.0 g/kg/day (mean +/- SD) and received 110 +/- 8 kcal/kg/day metabolizable energy (milk formula) and 522 +/- 40 mgN/kg/day. Their total energy expenditure was 68 +/- 4 kcal/kg/day indicating that 41 +/- 7 kcal/kg/day was retained for growth. Based on the combination of energy + N balances it was estimated that 80% of the weight gain was fat-free tissue and 20% was fat tissue. The rate of energy expenditure measured minute-by-minute was significantly and linearly correlated with the activity score in both the premeal (r = 0.75;p less than 0.001) and the postmeal periods (r = 0.74; p less than 0.001) with no difference in the regression slope, but with a significant difference in intercept. In preset feeding schedules the latter allowed an estimation of the thermogenic effect without the confounding effect of activity. This was found to be 3.1 +/- 1.8% when expressed as a percentage of metabolizable energy intake. However when the "classical" approach was used as a comparison (integration of extra energy expenditure induced by the meal), the thermogenic effect was found to be greater, i.e. 9.5 +/- 3.8% of the meal's metabolizable energy, due to the superimposed effect of physical activity in the postprandial state.(ABSTRACT TRUNCATED AT 250 WORDS)

" 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.

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.

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.

Arabidopsis Basic Helix-Loop-Helix Transcription Factors MYC2, MYC3, and MYC4 Regulate Glucosinolate Biosynthesis, Insect Performance, and Feeding Behavior.

Arabidopsis thaliana plants fend off insect attack by constitutive and inducible production of toxic metabolites, such as glucosinolates (GSs). A triple mutant lacking MYC2, MYC3, and MYC4, three basic helix-loop-helix transcription factors that are known to additively control jasmonate-related defense responses, was shown to have a highly reduced expression of GS biosynthesis genes. The myc2 myc3 myc4 (myc234) triple mutant was almost completely devoid of GS and was extremely susceptible to the generalist herbivore Spodoptera littoralis. On the contrary, the specialist Pieris brassicae was unaffected by the presence of GS and preferred to feed on wild-type plants. In addition, lack of GS in myc234 drastically modified S. littoralis feeding behavior. Surprisingly, the expression of MYB factors known to regulate GS biosynthesis genes was not altered in myc234, suggesting that MYC2/MYC3/MYC4 are necessary for direct transcriptional activation of GS biosynthesis genes. To support this, chromatin immunoprecipitation analysis showed that MYC2 binds directly to the promoter of several GS biosynthesis genes in vivo. Furthermore, yeast two-hybrid and pull-down experiments indicated that MYC2/MYC3/MYC4 interact directly with GS-related MYBs. This specific MYC-MYB interaction plays a crucial role in the regulation of defense secondary metabolite production and underlines the importance of GS in shaping plant interactions with adapted and nonadapted herbivores.

Circadian and feeding rhythms differentially affect rhythmic mRNA transcription and translation in mouse liver.

Diurnal oscillations of gene expression are a hallmark of rhythmic physiology across most living organisms. Such oscillations are controlled by the interplay between the circadian clock and feeding rhythms. Although rhythmic mRNA accumulation has been extensively studied, comparatively less is known about their transcription and translation. Here, we quantified simultaneously temporal transcription, accumulation, and translation of mouse liver mRNAs under physiological light-dark conditions and ad libitum or night-restricted feeding in WT and brain and muscle Arnt-like 1 (Bmal1)-deficient animals. We found that rhythmic transcription predominantly drives rhythmic mRNA accumulation and translation for a majority of genes. Comparison of wild-type and Bmal1 KO mice shows that circadian clock and feeding rhythms have broad impact on rhythmic gene expression, Bmal1 deletion affecting surprisingly both transcriptional and posttranscriptional levels. Translation efficiency is differentially regulated during the diurnal cycle for genes with 5'-Terminal Oligo Pyrimidine tract (5'-TOP) sequences and for genes involved in mitochondrial activity, many harboring a Translation Initiator of Short 5'-UTR (TISU) motif. The increased translation efficiency of 5'-TOP and TISU genes is mainly driven by feeding rhythms but Bmal1 deletion also affects amplitude and phase of translation, including TISU genes. Together this study emphasizes the complex interconnections between circadian and feeding rhythms at several steps ultimately determining rhythmic gene expression and translation.