Salicylic acid and ethylene pathways are differentially activated in melon cotyledons by active or heat-denatured cellulase from Trichoderma longibrachiatum

Infiltration of cellulase (EC 3.2.1.4) from Trichoderma longibrachiatum into melon (Cucumis melo) cotyledons induced several key defense mechanisms and hypersensitive reaction-like symptoms. An oxidative burst was observed 3 hours after treatment and was followed by activation of ethylene and salicylic acid (SA) signaling pathways leading to marked induction of peroxidase and chitinase activities. The treatment of cotyledons by heat-denatured cellulase also led to some induction of peroxidase and chitinase activities, but the oxidative burst and SA production were not observed. Co-infiltration of aminoethoxyvinil-glycine (an ethylene inhibitor) with the active cellulase did not affect the high increase of peroxidase and chitinase activities. In contrast, co-infiltration of aminoethoxyvinil-glycine with the denatured enzyme blocked peroxidase and chitinase activities. Our data suggest that the SA pathway (induced by the cellulase activity) and ethylene pathway (induced by heat-denatured and active protein) together coordinate the activation of defense mechanisms. We found a partial interaction between both signaling pathways since SA caused an inhibition of the ethylene production and a decrease in peroxidase activity when co-infiltrated with denatured cellulase. Treatments with active or denatured cellulase caused a reduction in powdery mildew (Sphaerotheca fuliginea) disease.     

3D realtime echography and echography assisted by a robotic arm for investigating astronauts in the ISS from the ground

As human will stay for long duration in isolated sites like ISS there will be a need to perform quick and reliable diagnosis to evaluate the gravity of the pathology in presence of clinical symptoms. Many pathological situations (abnormal heart rate, pericardic collection, mitral prolaps, cholecystis, renal lithiasis, normal and ectopic pregnancies, ovarian cyst, acute appendicitis, phlebitis ... ) may occur even if all the astronauts are absolutely normal and healthy preflight. Ultrasound echography and Doppler are non invasive methods easy to use in space and very well adapted and used in routine for such diagnosis at the hospital. The objective of the present project was to design a method that guarantee a reliable echographic diagnostic in an isolated site (space station or earth site) by a Medical Doctor located at the expert site that should be the Nasa control center for ISS. It is supposed that there is only a non sonographer person in the isolated site and that the transmission system (audio, video, numeric..) is the only link between the 2 sites. Two options are proposed: (a) A 3D realtime acquisition echograph that can record quickly all the echos of a volume containing the organ suspected to have a lesion, all these echo information being sent to the ground and processed by the ground experts, (b) A robotic arm that hangs the echo probe in the isolated site tele-operated (through sattelite network) from the ground by an expert in clinical ultrasound. (As the expert moves the joystick of his ground computer the robotic arm reproduces the same movements on the probe).     

Modulation, by transforming growth factor beta (TGF beta), of the mitogenic effect of fibroblast growth factor (FGF) on rat oligodendrocytes in culture

The transforming growth factor beta (TGF beta) is a weak mitogen for rat oligodendrocytes grown in serum-free chemically defined medium. When these cells were treated by basic fibroblast growth factor (bFGF), which is the most potent known mitogen for cultured oligodendrocytes, together with TGF beta we observed that at low doses TGF beta potentiates the mitogenic effect of bFGF while at higher concentrations it partly inhibits this effect.     

Activities of thiamine-dependent enzymes in two experimental models of thiamine-deficiency encephalopathy:

Chronic thiamine deprivation in the rat leads to selective neuropathological damage in brainstem structures whereas treatment with the central thiamine antagonist, pyrithiamine, results in more widespread damage. In order to further elucidate the neurochemical mechanisms responsible for this selective damage, the thiamine-dependent enzyme complex pyruvate dehydrogenase (PDHC) was measured in 10 brain structures in the rat during progression of thiamine deficiency produced by chronic deprivation or by pyrithiamine treatment. Feeding of a thiamine-deficient diet to adult rats resulted in 5–7 weeks in ataxia and loss of righting reflex accompanied by decreased blood transketolase activities. PDHC activities were selectively decreased by 15–30% in midbrain and pons (lateral vestibular nucleus). Thiamine treatment of symptomatic rats led to reversal of neurological signs and to concomitant reductions of the cerebral PDHC abnormalities. Daily pyrithiamine treatment led within 3 weeks to loss of righting reflex and convulsions and to decreased blood transketolase of a comparable magnitude to that observed in chronic thiamine-deprived rats. No significant regional alterations of PDHC, however, were observed in pyrithiamine-treated rats.     

Applying DNA barcoding for the study of geographical variation in host-parasitoid interactions

Studies on the biogeography of host-parasitoid interactions are scarce, mainly because of technical difficulties associated with rearing and species identification. DNA barcoding is increasingly recognized as a valuable tool for taxon identification, allowing to link different life history stages of a species. We evaluate the usefulness of a protocol based on cytochrome oxidase I (COI) sequencing for the study of geographical variation of host-parasitoid interactions. Larvae of Acroclita subsequana (Lepidoptera: Tortricidae) were collected in Macaronesia and dissected to search for parasitoid larvae. Both hosts and parasitoids were sequenced and assigned to molecular operational taxonomic units (MOTUs) based on pairwise genetic distances, tree-based and similarity-based methods. Hosts were grouped into six MOTUs, usually with an allopatric distribution, while parasitoids clustered into 12 MOTUs, each of which was mostly found attacking a single host MOTU. Available COI sequence databases failed to provide identification to species level for these MOTUs. Three challenges related to the applicability of DNA barcoding in this type of studies are identified and discussed: (i) more suitable primers need to be developed for both parasitoids and hosts; (ii) the most commonly used approaches for inferring MOTUs have different limitations (e.g. arbitrary nature of defining a threshold to separate MOTUs) and need to be improved or replaced by other techniques; and (iii) for the identification of MOTUs, it is imperative to increase the range of sequenced taxa in the currently available reference databases. Finally, in spite of these difficulties, we discuss how DNA barcoding will help ecological and biogeographical studies of host-parasitoid interactions.     

Population genetics of Mediterranean and Saharan olives: geographic patterns of differentiation and evidence for early generations of admixture

Background and Aims

The olive (Olea europaea subsp. europaea) was domesticated in the Mediterranean area but its wild relatives are distributed over three continents, from the Mediterranean basin to South Africa and south-western Asia. Recent studies suggested that this crop originated in the Levant while a secondary diversification occurred in most westward areas. A possible contribution of the Saharan subspecies (subsp. laperrinei) has been highlighted, but the data available were too limited to draw definite conclusions. Here, patterns of genetic differentiation in the Mediterranean and Saharan olives are analysed to test for recent admixture between these taxa.

Methods

Nuclear microsatellite and plastid DNA (ptDNA) data were compiled from previous studies and completed for a sample of 470 cultivars, 390 wild Mediterranean trees and 270 Saharan olives. A network was reconstructed for the ptDNA haplotypes, while a Bayesian clustering method was applied to identify the main gene pools in the data set and then simulate and test for early generations of admixture between Mediterranean and Saharan olives.

Key Results

Four lineages of ptDNA haplotypes are recognized: three from the Mediterranean basin and one from the Sahara. Only one haplotype, primarily distributed in the Sahara, is shared between laperrinei and europaea. This haplotype is detected once in ‘Dhokar’, a cultivar from the Maghreb. Nuclear microsatellites show geographic patterns of genetic differentiation in the Mediterranean olive that reflect the primary origins of cultivars in the Levant, and indicate a high genetic differentiation between europaea and laperrinei. No first-generation hybrid between europaea and laperrinei is detected, but recent, reciprocal admixture between Mediterranean and Saharan subspecies is found in a few accessions, including ‘Dhokar’.

Conclusions

This study reports for the first time admixture between Mediterranean and Saharan olives. Although its contribution remains limited, Laperrine''s olive has been involved in the diversification of cultivated olives.     

Density dependence in Golden Eagle Aquila chrysaetos fecundity better explained by individual adjustment than territory heterogeneity

Density-dependence effects acting on fecundity can be explained by two competing hypotheses. The individual adjustment hypothesis (IAH) states that, as population density increases, interference among individuals negatively affects their breeding performance. The second hypothesis, the habitat heterogeneity hypothesis (HHH), proposes that, as more individuals occupy the space available, lower quality habitats are increasingly used, causing average population fecundity to decline. In territorial species, it is often predicted that interference mechanisms (IAH) should be of less importance than spatial heterogeneity (HHH). Here, we test this prediction in Golden Eagles, using 35 years of reproduction monitoring data from a population that has been recolonizing the grounds of a French National Park (Ecrins) in the Alps. During the study period, the Eagle population increased from c. 11 to 41 territorial pairs, providing a good opportunity to explicitly assess fecundity across a gradient of densities. Under the IAH, we expect the fecundity of all territories to diminish as density rises. Under strict HHH, older territories should maintain higher fecundity across time, and a positive relationship between fecundity and the seniority of a territory should be observed. A density-dependent pattern was clearly detected at the population level. At the territory level, the decrease of fecundity was strongly related to population size but not to territory seniority. Fecundity decreased similarly in all territories, suggesting that the IAH better explains the observed pattern. Two alternative mechanisms, related to the IAH, could be at play in this population: (1) negative interference by neighbours and non-territorial Eagles and (2) the contraction of individual territories over time. Our results provide new insights into density dependence in territorial raptors, suggesting that, in addition to habitat heterogeneity, interference mechanisms might actually also play an important role.     

A first linkage map of olive (Olea europaea L.) cultivars using RAPD,AFLP, RFLP and SSR markers

The first linkage map of the olive (Olea europaea L.) genome has been constructed using random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphisms (AFLP) as dominant markers and a few restriction fragment length polymorphisms (RFLP) and simple-sequence repeats (SSR) as codominant markers. Ninety-five individuals of a cross progeny derived from two highly heterozygous olive cultivars, Leccino and Dolce Agogia, were used by applying the pseudo test-cross strategy. From 61 RAPD primers 279 markers were obtained - 158 were scored for Leccino and 121 for Dolce Agogia. Twenty-one AFLP primer combinations gave 304 useful markers - 160 heterozygous in Leccino and 144 heterozygous in Dolce Agogia. In the Leccino map 249 markers (110 RAPD, 127 AFLP, 8 RFLP and 3 SSR) were linked. This resulted in 22 major linkage groups and 17 minor groups with fewer than four markers. In the Dolce Agogia map, 236 markers (93 RAPD, 133 AFLP, 6 RFLP and 4 SSR) were linked; 27 major linkage groups and three minor groups were obtained. Codominant RFLPs and SSRs, as well as few RAPDs in heteroduplex configuration, were used to establish homologies between linkage groups of both parents. The total distance covered was 2,765 cM and 2,445 cM in the Leccino and Dolce Agogia maps, respectively. The mean map distance between adjacent markers was 13.2 cM in Leccino and 11.9 cM in Dolce Agogia, respectively. Both AFLP and RAPD markers were homogeneously distributed in all of the linkage groups reported. The stearoyl-ACP desaturase gene was mapped on linkage group 4 of cv. Leccino.