Ultrastructure des spermatozoïdes mûrs de trois Bucephalidae (Prosorhynchus longisaccatus, Rhipidocotyle khalili et Bucephalus margaritae) et implications phylogénétiques.

International audienceWe describe here the mature spermatozoa of three species of bucephalids, namely Bucephalus margar-itae, Rhipidocotyle khalili and Prosorhynchus longisaccatus. This study provides the first ultrastructural data on the genera Bucephalus and Rhipidocotyle and enabled us to confirm the model of the mature spermatozoon in the Bucephalinae. The spermatozoon exhibits two axonemes with the 9 + ''1'' pattern of the Trepaxonemata, one of which is very short, lateral expansion, external ornamentation of the plasma membrane located in the anterior extremity of the spermatozoon and associated with cortical microtubules, spine-like bodies, a mitochondrion, and a nucleus. The maximum number of cortical microtubules is located in the anterior part of the spermatozoon. However, more studies are needed to elucidate if spine-like bodies are present in all the Bucephalinae or not. In the Prosorhynchinae, the mature spermatozoon exhibits a similar ultrastructural pattern. Some differences are observed, particularly the ax-oneme lengths and the arrangement of the spine-like bodies. The posterior extremity of the spermatozoon in the Bucephalinae exhibits only the nucleus, but prosorhynchines have microtubules.Dans cette étude, nous décrivons les spermatozoïdes mûrs de trois espèces de bucephalidés, à savoir Bucephalus margaritae, Rhipidocotyle khalili et Prosorhynchus longisaccatus. Ces premières données ultrastructurales pour les genres Bucephalus et Rhipidocotyle nous ont permis de confirmer le modèle du spermatozoïde chez les Bucephalinae. Le spermatozoïde comprend deux axonèmes de type 9 + ‘‘1’’ des Trepaxonemata, l’un d’entre eux étant très court, une expansion latérale, une ornementation externe de la membrane plasmique située au niveau de l’extrémité antérieure du spermatozoïde et associée avec des microtubules corticaux, des corps en forme d’épines, une mitochondrie et un noyau. Le nombremaximum de microtubules corticaux est situé dans la partie antérieure du spermatozoïde. Toutefois, des études supplémentaires seraient nécessaires pour vérifier si les corps en forme d’épines sont présents chez tous les Bucephalinae. Chez les Prosorhynchinae, le spermatozoïde mûr présente une structure similaire. Quelques différences sont toutefois observées, notamment au niveau de la longueur des axonèmes et de la disposition des corps en forme d’épines. L’extrémité postérieure du spermatozoïde chez les Bucephalidae est caractérisée par la présence du noyau seul, alors que les Prosorhynchinae ont des microtubules

Carotenoids of microalgae used in food industry and medicine

International audienc

Diatom milking? A review and new approaches

The rise of human populations and the growth of cities contribute to the depletion of natural resources, increase their cost, and create potential climatic changes. To overcome difficulties in supplying populations and reducing the resource cost, a search for alternative pharmaceutical, nanotechnology, and energy sources has begun. Among the alternative sources, microalgae are the most promising because they use carbon dioxide (CO2) to produce biomass and/or valuable compounds. Once produced, the biomass is ordinarily harvested and processed (downstream program). Drying, grinding, and extraction steps are destructive to the microalgal biomass that then needs to be renewed. The extraction and purification processes generate organic wastes and require substantial energy inputs. Altogether, it is urgent to develop alternative downstream processes. Among the possibilities, milking invokes the concept that the extraction should not kill the algal cells. Therefore, it does not require growing the algae anew. In this review, we discuss research on milking of diatoms. The main themes are (a) development of alternative methods to extract and harvest high added value compounds; (b) design of photobioreactors; (c) biodiversity and (d) stress physiology, illustrated with original results dealing with oleaginous diatoms

First spermatological study in the Atractotrematidae (Digenea, Haploporoidea): the case of Atractotrema sigani, intestinal parasite of Siganus lineatus

The ultrastructural organization of the mature spermatozoon of the digenean Atractotrema sigani(from Siganus lineatus off New Caledonia) was investigated by transmission electron microscopy. The male gamete of A. sigani exhibits the general morphology described in digeneans with the presence of two axonemes of different lengths showing the 9 + '1' pattern of the Trepaxonemata, a nucleus, two mitochondria, two bundles of parallel cortical microtubules, external ornamentation, spine-like bodies and granules of glycogen. However, the mature spermatozoon of A. sigani has some specific characters such as the morphology of its anterior region and the submembranous electron-dense material. Although similar structures have been reported in some digenean species, the presence of a submembranous electron-dense material describing a complete ring is reported here for the first time in the mature spermatozoon of A. sigani. In addition, sperm characteristics are compared between the Haploporoidea and their supposed close superfamilies, and possible phylogenetic implications of these findings for the Digenea are discussed

CommsChem

Connecting chemical properties to various wine characteristics is of great interest to the science of olfaction as well as the wine industry. We explored whether Bordeaux wine chemical identities and vintages (harvest year) can be inferred from a common and affordable chemical analysis, namely, a combination of gas chromatography (GC) and electron ionization mass spectrometry. Using 12 vintages (within the 1990–2007 range) from 7 estates of the Bordeaux region, we report that, remarkably, nonlinear dimensionality reduction techniques applied to raw gas chromatograms recover the geography of the Bordeaux region. Using machine learning, we found that we can not only recover the estate perfectly from gas chromatograms, but also the vintage with up to 50% accuracy. Interestingly, we observed that the entire chromatogram is informative with respect to geographic location and age, thus suggesting that the chemical identity of a wine is not defined by just a few molecules but is distributed over a large chemical spectrum. This study demonstrates the remarkable potential of GC analysis to explore fundamental questions about the origin and age of wine. © 2023, The Author(s)

Comparison of two Phaeodactylum tricornutum ecotypes under nitrogen starvation and resupply reveals distinct lipid accumulation strategies but a common degradation process

IntroductionPhaeodactylum tricornutum is a model species frequently used to study lipid metabolism in diatoms. When exposed to a nutrient limitation or starvation, diatoms are known to accumulate neutral lipids in cytoplasmic lipid droplets (LDs). Those lipids are produced partly de novo and partly from the recycle of plastid membrane lipids. Under a nitrogen resupply, the accumulated lipids are catabolized, a phenomenon about which only a few data are available. Various strains of P. tricornutum have been isolated around the world that may differ in lipid accumulation patterns.MethodsTo get further information on this topic, two genetically distant ecotypes of P. tricornutum (Pt1 and Pt4) have been cultivated under nitrogen deprivation during 11 days followed by a resupply period of 3 days. The importance of cytoplasmic LDs relative to the plastid was assessed by a combination of confocal laser scanning microscopy and cell volume estimation using bright field microscopy pictures.Results and discussionWe observed that in addition to a basal population of small LDs (0.005 μm3 to 0.7 μm3) present in both strains all along the experiment, Pt4 cells immediately produced two large LDs (up to 12 μm3 after 11 days) while Pt1 cells progressively produced a higher number of smaller LDs (up to 7 μm3 after 11 days). In this work we showed that, in addition to intracellular available space, lipid accumulation may be limited by the pre-starvation size of the plastid as a source of membrane lipids to be recycled. After resupplying nitrogen and for both ecotypes, a fragmentation of the largest LDs was observed as well as a possible migration of LDs to the vacuoles that would suggest an autophagic degradation. Altogether, our results deepen the understanding of LDs dynamics and open research avenues for a better knowledge of lipid degradation in diatoms

Serge Tousignant : jeux d'espaces, jeux de regards : le catalogue

L'exposition qui fait l'objet de ce catalogue a malheureusement été annulée à cause de la pandémie, mais elle aurait dû se tenir au Carrefour des arts et des sciences de l’Université de Montréal du 8 avril au 12 juin 2020.Catalogue d'exposition préparé à l'hiver 2020 dans le cadre du cours HAR 6080 / MSL 6509 : Muséologie et histoire de l'art, donné par la professeure Christine Bernier.Catalogue préparé sous la direction de Christine Bernie

Publisher Correction: A PRDX1 mutant allele causes a MMACHC secondary epimutation in cblC patients

The original version of this Article contained an error in the title, which was incorrectly given as 'APRDX1 mutant allele causes a MMACHC secondary epimutation in cblC patients'. This has now been corrected in both the PDF and HTML versions of the Article to read 'A PRDX1 mutant allele causes a MMACHC secondary epimutation in cblC patients'

Les droits disciplinaires des fonctions publiques : « unification », « harmonisation » ou « distanciation ». A propos de la loi du 26 avril 2016 relative à la déontologie et aux droits et obligations des fonctionnaires

The production of tt‾ , W+bb‾ and W+cc‾ is studied in the forward region of proton–proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98±0.02 fb−1 . The W bosons are reconstructed in the decays W→ℓν , where ℓ denotes muon or electron, while the b and c quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions.The production of $t\overline{t}$, $W+b\overline{b}$ and $W+c\overline{c}$ is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98 $\pm$ 0.02 \mbox{fb}^{-1}. The $W$ bosons are reconstructed in the decays $W\rightarrow\ell\nu$, where $\ell$ denotes muon or electron, while the $b$ and $c$ quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions

Observation of the B0 → ρ0ρ0 decay from an amplitude analysis of B0 → (π+π−)(π+π−) decays

Proton–proton collision data recorded in 2011 and 2012 by the LHCb experiment, corresponding to an integrated luminosity of 3.0 fb−1 , are analysed to search for the charmless B0→ρ0ρ0 decay. More than 600 B0→(π+π−)(π+π−) signal decays are selected and used to perform an amplitude analysis, under the assumption of no CP violation in the decay, from which the B0→ρ0ρ0 decay is observed for the first time with 7.1 standard deviations significance. The fraction of B0→ρ0ρ0 decays yielding a longitudinally polarised final state is measured to be fL=0.745−0.058+0.048(stat)±0.034(syst) . The B0→ρ0ρ0 branching fraction, using the B0→ϕK⁎(892)0 decay as reference, is also reported as B(B0→ρ0ρ0)=(0.94±0.17(stat)±0.09(syst)±0.06(BF))×10−6