Total Synthesis of (Nor)illudalane Sesquiterpenes Based on a C(sp3)-H Activation Strategy

Three (nor)illudalane sesquiterpenes were synthesized from a common intermediate in racemic and enantioenriched forms using Pd0-catalyzed C(sp3)-H arylation as a key step. The configuration of the isolated, highly symmetric quaternary stereocenter of the target molecules was controlled through a matched combination of chiral substrate and catalyst. Moreover, the recently developed Ir-catalyzed C-H borylation/Cu-catalyzed methylation method was employed to install the methyl group on the benzene ring. This strategy allowed the efficient synthesis of both racemic and (S)-configured puraquinonic acid, deliquinone, and russujaponol F

Identification de seuils écologiques à partir des variations des communautés de phytoplancton entre les lacs : contribution à la définition de normes environnementales

International audienceIn aquatic ecosystems, the identification of ecological thresholds may be useful for managers as it can help to diagnose ecosystem health and to identify key levers to enable the success of preservation and restoration measures. A recent statistical method, gradient forest, based on random forests, was used to detect thresholds of phytoplankton community change in lakes along different environmental gradients. It performs exploratory analyses of multivariate biological and environmental data to estimate the location and importance of community thresholds along gradients. The method was applied to a data set of 224 French lakes which were characterized by 29 environmental variables and the mean abundances of 196 phytoplankton species. Results showed the high importance of geographic variables for the prediction of species abundances at the scale of the study. A second analysis was performed on a subset of lakes defined by geographic thresholds and presenting a higher biological homogeneity. Community thresholds were identified for the most important physico-chemical variables including water transparency, total phosphorus, ammonia, nitrates, and dissolved organic carbon. Gradient forest appeared as a powerful method at a first exploratory step, to detect ecological thresholds at large spatial scale. The thresholds that were identified here must be reinforced by the separate analysis of other aquatic communities and may be used then to set protective environmental standards after consideration of natural variability among lakes

Divergent Enantioselective Synthesis of (Nor)illudalane Sesquiterpenes via Pd-0-Catalyzed Asymmetric C(sp(3))-H Activation

A divergent enantioselective synthesis of (nor)-illudalane sesquiterpenes was designed by using a Pd-0-catalyzed asymmetric C(sp(3))-H arylation as a key step to control the isolated, highly symmetric quaternary stereocenter of the target molecules. A matched combination of chiral substrate and catalyst proved optimal to reach good levels of stereoselectivity. This approach enabled the synthesis of three (nor)illudalanes, including (S)-deliquinone and (S)-russujaponol F, which are synthesized for the first time in enantioenriched form

Comparison of urinary scents of two related mouse species, Mus spicilegus and Mus domesticus.

International audienceWhereas the house mouse (Mus domesticus) has been studied extensively in terms of physiology/behavior and pheromonal attributes, the evolutionarily related mound-building mouse (Mus spicilegus) has received attention only recently due to its divergent behavioral traits related to olfaction. To date, no chemical studies on urinary volatile compounds have been performed on M. spicilegus. The rationale for our investigations was to determine if there are differences in urinary volatiles of intact and castrated M. spicilegus males and to explore further whether this species could utilize the same or structurally similar pheromones as the male house mouse, M. domesticus. The use of capillary gas chromatography/mass spectrometry (GC-MS) together with sorptive stir bar extraction sampling enabled quantitative comparisons between the intact and castrated M. spicilegus urinary profiles. Additionally, through GC-MS and atomic emission (sulfur-selective) detection, we identified qualitative molecular differences between intact M. spicilegus and M. domesticus. A series of volatile and odoriferous lactones and the presence of coumarin were the unique features of M. spicilegus, as was the notable absence of 2-sec-butyl-4,5-dihydrothiazole (a prominent M. domesticus male pheromone) and other sulfur-containing compounds. Castration of M. spicilegus males eliminated several substances, including delta-hexalactone and gamma-octalactone, and substantially decreased additional compounds, suggesting their possible role in chemical communication. Some other M. domesticus pheromone components were also found in M. spicilegus urine. These comparative chemical analyses support the notion of metabolic similarities as well as the uniqueness of some volatiles for M. spicilegus, which may have a distinct physiological function in reproduction and behavior

Stochastic B\"acklund transformations

How does one introduce randomness into a classical dynamical system in order to produce something which is related to the `corresponding' quantum system? We consider this question from a probabilistic point of view, in the context of some integrable Hamiltonian systems

Relative frequencies of inherited retinal dystrophies and optic neuropathies in Southern France: assessment of 21-year data management

PURPOSE: Inherited retinal dystrophies (IRDs) and inherited optic neuropathies (IONs) are rare diseases defined by specific clinical and molecular features. The relative prevalence of these conditions was determined in Southern France. METHODS: Patients recruited from a specialized outpatient clinic over a 21-year period underwent extensive clinical investigations and 107 genes were screened by polymerase chain reaction/sequencing. RESULTS: There were 1957 IRD cases (1481 families) distributed in 70% of pigmentary retinopathy cases (56% non-syndromic, 14% syndromic), 20% maculopathies and 7% stationary conditions. Patients with retinitis pigmentosa were the most frequent (47%) followed by Usher syndrome (10.8%). Among non-syndromic pigmentary retinopathy patients, 84% had rod-cone dystrophy, 8% cone-rod dystrophy and 5% Leber congenital amaurosis. Macular dystrophies were encountered in 398 cases (30% had Stargardt disease and 11% had Best disease). There were 184 ION cases (127 families) distributed in 51% with dominant optic neuropathies, 33% with recessive/sporadic forms and 16% with Leber hereditary optic neuropathy. Positive molecular results were obtained in 417/609 families with IRDs (68.5%) and in 27/58 with IONs (46.5%). The sequencing of 5 genes (ABCA4, USH2A, MYO7A, RPGR and PRPH2) provided a positive molecular result in 48% of 417 families with IRDs. Except for autosomal retinitis pigmentosa, in which less than half the families had positive molecular results, about 75% of families with other forms of retinal conditions had a positive molecular diagnosis. CONCLUSIONS: Although gene discovery considerably improved molecular diagnosis in many subgroups of IRDs and IONs, retinitis pigmentosa, accounting for almost half of IRDs, remains only partly molecularly defined