Forces,failles et opportunités de la recherche française en écologie trophique

The French National Institute of Ecology and Environment (INEE) aims at fostering pluridisciplinarity in Environmental Science and, for that purpose, funds ex muros research groups (GDR) on thematic topics. Trophic ecology has been identified as a scientific field in ecology that would greatly benefit from such networking activity, as being profoundly scattered. This has motivated the seeding of a GDR, entitled “GRET”. The contours of the GRET's action, and its ability to fill these gaps within trophic ecology at the French national scale, will depend on the causes of this relative scattering. This study relied on a nationally broadcasted poll aiming at characterizing the field of trophic ecology in France. Amongst all the unique individuals that fulfilled the poll, over 300 belonged at least partly to the field of trophic ecology. The sample included all French public research institutes and career stages. Three main disruptions within the community of scientist in trophic ecology were identified. The first highlighted the lack of interfaces between microbial and trophic ecology. The second evidenced that research questions were strongly linked to single study fields or ecosystem type. Last, research activities are still quite restricted to the ecosystem boundaries. All three rupture points limit the conceptual and applied progression in the field of trophic ecology. Here we show that most of the disruptions within French Trophic Ecology are culturally inherited, rather than motivated by scientific reasons or justified by socio-economic stakes. Comparison with the current literature confirms that these disruptions are not necessarily typical of the French research landscape, but instead echo the general weaknesses of the international research in ecology. Thereby, communication and networking actions within and toward the community of trophic ecologists, as planned within the GRET's objectives, should contribute to fill these gaps, by reintegrating microbes within trophic concepts and setting the seeds for trans- and meta-ecosystemic research opportunities. Once the community of trophic ecologists is aware of the scientific benefit in pushing its boundaries forwards, turning words and good intentions into concrete research projects will depend on the opportunities to obtain research funding.     

PtxtPME1 and homogalacturonans influence xylem hydraulic properties in poplar

While the xylem hydraulic properties, such as vulnerability to cavitation (VC), are of paramount importance in drought resistance, their genetic determinants remain unexplored. There is evidence that pectins and their methylation pattern are involved, but the detail of their involvement and the corresponding genes need to be clarified. We analyzed the hydraulic properties of the 35S::PME1 transgenic aspen that ectopically under‐ or over‐express a xylem‐abundant pectin methyl esterase, PtxtPME1. We also produced and analyzed 4CL1::PGII transgenic poplars expressing a fungal polygalacturonase, AnPGII, under the control of the Ptxa4CL1 promoter that is active in the developing xylem after xylem cell expansion. Both the 35S::PME1 under‐ and over‐expressing aspen lines developed xylem with lower‐specific hydraulic conductivity and lower VC, while the 4CL1::PGII plants developed xylem with a higher VC. These xylem hydraulic changes were associated with modifications in xylem structure or in intervessel pit structure that can result in changes in mechanical behavior of the pit membrane. This study shows that homogalacturonans and their methylation pattern influence xylem hydraulic properties, through its effect on xylem cell expansion and on intervessel pit properties and it show a role for PtxtPME1 in the xylem hydraulic properties.     

A chemotaxonomic survey of kaurene derivatives in the genus Alepidea (Apiaceae)

Lipophilic extracts from the roots of 16 species of Alepidea were studied by GC-MS for the presence of kaurenoic acids, dehydrokaurenoic acids, kaurenic lactones, hydroxykaurenoic acids and other kaurene derivatives. Various mixtures of these compounds are present in yields of up to 11.8% dry wt. in the rhizomes and roots. Two different isomers of kaurenoic acid occur in Alepidea, the one as a major compound in all the species, the other as a major compound only in some of them. The first isomer is clearly a useful chemical marker for the genus Alepidea, but the apparent chemical dichotomy is not obviously correlated with morphological patterns. Alepidea amatymbica, however, is part of a morphologically isolated group within the genus and also differs from other species in its chemical complexity and in the unique presence of kaurenoic lactones.     

Identification of Medicare Recipients at Highest Risk for Clostridium difficile Infection in the US by Population Attributable Risk Analysis

Background

Population attributable risk percent (PAR%) is an epidemiological tool that provides an estimate of the percent reduction in total disease burden if that disease could be entirely eliminated among a subpopulation. As such, PAR% is used to efficiently target prevention interventions. Due to significant limitations in current Clostridium difficile Infection (CDI) prevention practices and the development of new approaches to prevent CDI, such as vaccination, we determined the PAR% for CDI in various subpopulations in the Medicare 5% random sample.

Methods

This was a retrospective cohort study using the 2009 Medicare 5% random sample. Comorbidities, infections, and healthcare exposures during the 12 months prior to CDI were identified. CDI incidence and PAR% were calculated for each condition/exposure. Easy to identify subpopulations that could be targeted from prevention interventions were identified based on PAR%.

Findings

There were 1,465,927 Medicare beneficiaries with 9,401 CDI cases for an incidence of 677/100,000 persons. Subpopulations representing less than 15% of the entire population and with a PAR% ≥ 30% were identified. These included deficiency anemia (PAR% = 37.9%), congestive heart failure (PAR% = 30.2%), fluid and electrolyte disorders (PAR% = 29.6%), urinary tract infections (PAR% = 40.5%), pneumonia (PAR% = 35.2%), emergent hospitalization (PAR% = 48.5%) and invasive procedures (PAR% = 38.9%). Stratification by age and hospital exposures indicates hospital exposures are more strongly associated with CDI than age.

Significance

Small and identifiable subpopulations that account for relatively large proportions of CDI cases in the elderly were identified. These data can be used to target specific subpopulations for CDI prevention interventions.     

Is excessive running predictive of degenerative hip disease? Controlled study of former elite athletes.

OBJECTIVE--To determine the effects of regular long distance running on the state of the hips in later life. DESIGN--Retrospective study of a cohort of elite athletes and a group of normal, healthy, untrained controls examined 15 years after initial testing. SETTING--Research project at school for physical education and sports. SUBJECTS--27 Former long distance runners (mean age 42), nine former bobsleigh riders (mean age 42), and 23 normal, healthy, untrained men (mean age 35) who had been examined in 1973 and who agreed to re-examination in 1988. MAIN OUTCOME MEASURE--Radiological evidence of degenerative hip disease in 1988. RESULTS--Physiological and exercise characteristics of all subjects had been recorded in 1973, and in 1988 these measurements were repeated together with radiological examination of the hips. An additive radiological index of hip disease based on grades of subchondral sclerosis, osteophyte formation, and joint space narrowing was significantly increased among runners as compared with bobsleigh riders and untrained controls. After adjustment for age the significant effect of type of sports activity remained (p = 0.032). In multivariate analyses age and milage run in 1973 (97 km/week) emerged as independent, significant, and positive predictors of radiological signs of degenerative hip disease in 1988 (p = 0.017 and p = 0.024 respectively). Among runners alone running pace in 1973 rather than milage run was the stronger predictor of subsequent degenerative hip disease. The milage run in 1988 was not particularly predictive of the radiological index, but endurance in 1988 was inversely related to degenerative hip disease seen radiologically. CONCLUSION--Long term, high intensity, high milage running should not be dismissed as a potential risk factor for premature osteoarthritis of the hip.     

Specifically deuterated and tritiated auxins

Regiospecific syntheses of monodeuterated and monotritiated natural auxin (indole- 3-acetic acid), a synthetic auxin (naphthalene-1-acetic acid) and a photoaffinity labeling auxin (5-azidoindole-3-acetic acid) are described. These syntheses provide benzene-ring tritiated auxins for use in reversible and covalent binding studies.     

Persistent measles virus infection of a clonal line of neuroblastoma: Effect on neural differentiation

Murine neuroblastoma cells, chronically infected with measles virus were examined for changes in neural-specific function and structure as well as cellular growth and macromolecular synthesis. When exposed to neural differentiation-inducing culture conditions, neurite formation and acetylcholinesterase activity are significantly increased in control cultures but not in persistently infected cells. Infected cultures manifest a more rapid doubling time, but depressed RNA and protein synthesis at saturation densities. Higher concentrations of papavarine, a cyclic 3′–5′ AMP phosphodiesterase inhibitor, result in selective death of persistently infected cells.