The Amidohydrolases IAR3 and ILL6 Contribute to Jasmonoyl-Isoleucine Hormone Turnover and Generate 12-Hydroxyjasmonic Acid Upon Wounding in Arabidopsis Leaves

Jasmonates (JAs) are a class of signaling compounds that mediate complex developmental and adaptative responses in plants. JAs derive from jasmonic acid (JA) through various enzymatic modifications, including conjugation to amino acids or oxidation, yielding an array of derivatives. The main hormonal signal, jasmonoyl-l-isoleucine (JA-Ile), has been found recently to undergo catabolic inactivation by cytochrome P450-mediated oxidation. We characterize here two amidohydrolases, IAR3 and ILL6, that define a second pathway for JA-Ile turnover during the wound response in Arabidopsis leaves. Biochemical and genetic evidence indicates that these two enzymes cleave the JA-Ile signal, but act also on the 12OH-JA-Ile conjugate. We also show that unexpectedly, the abundant accumulation of tuberonic acid (12OH-JA) after wounding originates partly through a sequential pathway involving (i) conjugation of JA to Ile, (ii) oxidation of the JA-Ile conjugate, and (iii) cleavage under the action of the amidohydrolases. The coordinated actions of oxidative and hydrolytic branches in the jasmonate pathway highlight novel mechanisms of JA-Ile hormone turnover and redefine the dynamic metabolic grid of jasmonate conversion in the wound response.     

Drivers of vegetative dormancy across herbaceous perennial plant species

Vegetative dormancy, that is the temporary absence of aboveground growth for ≥ 1 year, is paradoxical, because plants cannot photosynthesise or flower during dormant periods. We test ecological and evolutionary hypotheses for its widespread persistence. We show that dormancy has evolved numerous times. Most species displaying dormancy exhibit life‐history costs of sprouting, and of dormancy. Short‐lived and mycoheterotrophic species have higher proportions of dormant plants than long‐lived species and species with other nutritional modes. Foliage loss is associated with higher future dormancy levels, suggesting that carbon limitation promotes dormancy. Maximum dormancy duration is shorter under higher precipitation and at higher latitudes, the latter suggesting an important role for competition or herbivory. Study length affects estimates of some demographic parameters. Our results identify life historical and environmental drivers of dormancy. We also highlight the evolutionary importance of the little understood costs of sprouting and growth, latitudinal stress gradients and mixed nutritional modes.     

Trophic overlap between sexes in the dimorphic African black oystercatcher foraging on an alien mussel

Sex‐specific feeding segregation related to sexual bill dimorphism has been described in several oystercatcher species, including the African black oystercatcher. For the latter, studies concerned only a small number of breeding pairs and were done prior the invasion of the South African rocky shores by the Mediterranean mussel, which is believed to have benefited oystercatchers by increasing overall biomass. Here, we investigated geographic variability in the segregation of diet, biometrics and body condition between sexes in the African species, in relation to changes in foraging habitats along the South African coastline, using stable isotope analyses. Males and females and their potential prey (mussels, limpets, polychaetes and ascidians) were sampled on the southern African west, south‐west and south‐east coasts for stable isotope analyses and biometrics and body conditions of birds were measured. Bill dimorphism occurred throughout the study area and south‐west males had lower body conditions than other males and females in general. Sexes displayed little differences in their δ¹³C ratios and in the relative consumption of the different prey throughout the study area, except on the south‐east coast where males were slightly depleted in ¹³C relative to females and the most abundant prey elsewhere (the Mediterranean mussel) is rare. Females were slightly but significantly enriched in ¹⁵N by 0.3‰ compared to their breeding partners and this did not link clearly to differences in diet. We argue that the combined effect of biogeographic variations in rocky shores diversity and biomass, heterogeneous invasion by the Mediterranean mussel on the South African coastline and bill dimorphism may have altered the sex‐specific feeding behaviour of oystercatchers differently between coastal regions and possibly had an additional cost for male oystercatchers faced with lower prey biomass and diversity on the south‐west coast.     

Do ecologically close species shift their daily activities when in sympatry? A test on chamois in the presence of mouflon

Temporal partitioning of daily activities between species may promote coexistence within animal communities by reducing behavioural interference, particularly when species highly overlap in the use of space and resources. Such a strategy may be used by Alpine chamois (Rupicapra rupicapra rupicapra) when in the presence of mouflon (Ovis gmelini musimon × Ovis sp.), an introduced highly gregarious species with a broader ecological niche, overlapping with that of chamois. Using simultaneous monitoring of 29 Global Positioning System‐collared chamois and 12 mouflon, we assessed the temporal variation in activity patterns of chamois amongst two subpopulations: one without mouflon and one with mouflon, during January and August, which are the two most extreme periods of spatial overlap of mouflon with chamois distribution. Substantial differences in activity patterns between chamois and mouflon were observed (mean 13.8 ± 10.5% in January and 10.6 ± 11.6% in August). More subtle differences appeared between both subpopulations of chamois and persisted, regardless of the spatial overlap with mouflon (3.2 ± 1.8% in January and 2.6 ± 1.5% in August), thus highlighting that there is no behavioural interference from mouflon on chamois. Our findings suggest that the temporal partitioning of daily activities between chamois and mouflon, although probably a result of species‐specific adaptations to environmental conditions, may contribute to their coexistence. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 621–626.     

Local and Systemic Cytokine Expression in Patients with Postherpetic Neuralgia

Background

Postherpetic neuralgia (PHN) is the painful complication of a varicella zoster virus reactivation. We investigated the systemic and local gene expression of pro- and anti-inflammatory cytokine expression in patients with PHN.

Methods

Thirteen patients with PHN at the torso (Th4-S1) were recruited. Skin punch biopsies were obtained from the painful and the contralateral painless body area for intraepidermal nerve fiber density (IENFD) and cytokine profiling. Additionally, blood was withdrawn for systemic cytokine expression and compared to blood values of healthy controls. We analyzed the gene expression of selected pro- and anti-inflammatory cytokines (tumor necrosis factor-alpha [TNF] and interleukins [IL]-1β, IL-2, and IL-8).

Results

IENFD was lower in affected skin compared to unaffected skin (p<0.05), while local gene expression of pro- and anti-inflammatory cytokines did not differ except for two patients who had 7fold higher IL-6 and 10fold higher IL-10 gene expression in the affected skin compared to the contralateral unaffected skin sample. Also, the systemic expression of cytokines in patients with PHN and in healthy controls was similar.

Conclusion

While the systemic and local expression of the investigated pro- and anti-inflammatory cytokines was not different from controls, this may have been influenced by study limitations like the low number of patients and different disease durations. Furthermore, other cytokines or pain mediators need to be considered.     

A Spatially Explicit Metapopulation Model and Cattle Trade Analysis Suggests Key Determinants for the Recurrent Circulation of Rift Valley Fever Virus in a Pilot Area of Madagascar Highlands

Rift Valley fever (RVF) is a vector-borne zoonotic disease that causes high morbidity and mortality in ruminants. In 2008–2009, a RVF outbreak affected the whole Madagascar island, including the Anjozorobe district located in Madagascar highlands. An entomological survey showed the absence of Aedes among the potential RVF virus (RVFV) vector species identified in this area, and an overall low abundance of mosquitoes due to unfavorable climatic conditions during winter. No serological nor virological sign of infection was observed in wild terrestrial mammals of the area, suggesting an absence of wild RVF virus (RVFV) reservoir. However, a three years serological and virological follow-up in cattle showed a recurrent RVFV circulation. The objective of this study was to understand the key determinants of this unexpected recurrent transmission. To achieve this goal, a spatial deterministic discrete-time metapopulation model combined with cattle trade network was designed and parameterized to reproduce the local conditions using observational data collected in the area. Three scenarios that could explain the RVFV recurrent circulation in the area were analyzed: (i) RVFV overwintering thanks to a direct transmission between cattle when viraemic cows calve, vectors being absent during the winter, (ii) a low level vector-based circulation during winter thanks to a residual vector population, without direct transmission between cattle, (iii) combination of both above mentioned mechanisms. Multi-model inference methods resulted in a model incorporating both a low level RVFV winter vector-borne transmission and a direct transmission between animals when viraemic cows calve. Predictions satisfactorily reproduced field observations, 84% of cattle infections being attributed to vector-borne transmission, and 16% to direct transmission. These results appeared robust according to the sensitivity analysis. Interweaving between agricultural works in rice fields, seasonality of vector proliferation, and cattle exchange practices could be a key element for understanding RVFV circulation in this area of Madagascar highlands.     

Influence of joint constraints on lower limb kinematics estimation from skin markers using global optimization

In order to obtain the lower limb kinematics from skin-based markers, the soft tissue artefact (STA) has to be compensated. Global optimization (GO) methods rely on a predefined kinematic model and attempt to limit STA by minimizing the differences between model predicted and skin-based marker positions. Thus, the reliability of GO methods depends directly on the chosen model, whose influence is not well known yet.This study develops a GO method that allows to easily implement different sets of joint constraints in order to assess their influence on the lower limb kinematics during gait. The segment definition was based on generalized coordinates giving only linear or quadratic joint constraints. Seven sets of joint constraints were assessed, corresponding to different kinematic models at the ankle, knee and hip: SSS, USS, PSS, SHS, SPS, UHS and PPS (where S, U and H stand for spherical, universal and hinge joints and P for parallel mechanism). GO was applied to gait data from five healthy males.Results showed that the lower limb kinematics, except hip kinematics, knee and ankle flexion–extension, significantly depend on the chosen ankle and knee constraints. The knee parallel mechanism generated some typical knee rotation patterns previously observed in lower limb kinematic studies. Furthermore, only the parallel mechanisms produced joint displacements.Thus, GO using parallel mechanism seems promising. It also offers some perspectives of subject-specific joint constraints.     

Gaseous environments modify reserve carbohydrate contents and cell survival in the brewing yeast <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

The use of H₂, He and O₂ during batch fermentation of Saccharomyces cerevisiae BRAS291 increased the final intracellular glycogen contents of the cells from 2-fold to 10-fold compared with a gas-free condition, and this depended on the gas applied. Differently, the intracellular trehalose contents increased from 2-fold to 10-fold in reducing conditions compared with more oxidizing conditions. During storage at 4°C, the viability of cells cultivated with gas was twice that of cells cultivated without gas. These results could be explained by the intracellular carbohydrate contents as well as yeast ultrastructural modifications observed previously.