Ontogenic effects of early feeding of sea bass (Dicentrarchus labrax) larvae with a range of dietary n-3 HUFA levels on the functioning of PUFA desaturation pathways

Four replicated groups of sea bass (Dicentrarchus labrax) larvae were fed diets containing an extra-high level of highly unsaturated fatty acids (HUFA) (XH; 3·7% EPA + DHA), a high level of HUFA (HH; 1·7 %), a low level of HUFA (LH; 0·7%) or an extra-low level of HUFA (XLH; 0·5%) from day 6 to day 45 (experiment 1; XH1, HH1, LH1, XLH1). After a subsequent 1-month period feeding a commercial diet (2·7% EPA + DHA), the capacity of the four initial groups to adapt to an n-3 HUFA-restricted diet (0·3% EPA + DHA; R-groups: XH2R, HH2R, LH2R, XLH2R) was tested for 35 d. Larval dietary treatments had no effect on larval and juvenile survival rates. The wet weight of day 45 larvae was higher in XH1 and HH1 (P < 0·001), but the R-juvenile mass gains were similar in all treatments. D-6-desaturase (D6D) mRNA level was higher in LH1 and XLH1 at day 45 (

Multidifferential study of identified charged hadron distributions in ZZ-tagged jets in proton-proton collisions at s=\sqrt{s}=13 TeV

Jet fragmentation functions are measured for the first time in proton-proton collisions for charged pions, kaons, and protons within jets recoiling against a $Z$ boson. The charged-hadron distributions are studied longitudinally and transversely to the jet direction for jets with transverse momentum 20 $< p_{\textrm{T}} < 100$ GeV and in the pseudorapidity range $2.5 < \eta < 4$. The data sample was collected with the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.64 fb$^{-1}$. Triple differential distributions as a function of the hadron longitudinal momentum fraction, hadron transverse momentum, and jet transverse momentum are also measured for the first time. This helps constrain transverse-momentum-dependent fragmentation functions. Differences in the shapes and magnitudes of the measured distributions for the different hadron species provide insights into the hadronization process for jets predominantly initiated by light quarks.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-013.html (LHCb public pages

Study of the B−→Λc+Λˉc−K−B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-} decay

The decay $B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-}$ is studied in proton-proton collisions at a center-of-mass energy of $\sqrt{s}=13$ TeV using data corresponding to an integrated luminosity of 5 $\mathrm{fb}^{-1}$ collected by the LHCb experiment. In the $\Lambda_{c}^+ K^{-}$ system, the $\Xi_{c}(2930)^{0}$ state observed at the BaBar and Belle experiments is resolved into two narrower states, $\Xi_{c}(2923)^{0}$ and $\Xi_{c}(2939)^{0}$, whose masses and widths are measured to be $$m(\Xi_{c}(2923)^{0}) = 2924.5 \pm 0.4 \pm 1.1 \,\mathrm{MeV}, \\ m(\Xi_{c}(2939)^{0}) = 2938.5 \pm 0.9 \pm 2.3 \,\mathrm{MeV}, \\ \Gamma(\Xi_{c}(2923)^{0}) = \phantom{000}4.8 \pm 0.9 \pm 1.5 \,\mathrm{MeV},\\ \Gamma(\Xi_{c}(2939)^{0}) = \phantom{00}11.0 \pm 1.9 \pm 7.5 \,\mathrm{MeV},$$ where the first uncertainties are statistical and the second systematic. The results are consistent with a previous LHCb measurement using a prompt $\Lambda_{c}^{+} K^{-}$ sample. Evidence of a new $\Xi_{c}(2880)^{0}$ state is found with a local significance of $3.8\,\sigma$, whose mass and width are measured to be $2881.8 \pm 3.1 \pm 8.5\,\mathrm{MeV}$ and $12.4 \pm 5.3 \pm 5.8 \,\mathrm{MeV}$, respectively. In addition, evidence of a new decay mode $\Xi_{c}(2790)^{0} \to \Lambda_{c}^{+} K^{-}$ is found with a significance of $3.7\,\sigma$. The relative branching fraction of $B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-}$ with respect to the $B^{-} \to D^{+} D^{-} K^{-}$ decay is measured to be $2.36 \pm 0.11 \pm 0.22 \pm 0.25$, where the first uncertainty is statistical, the second systematic and the third originates from the branching fractions of charm hadron decays.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-028.html (LHCb public pages

Measurement of the ratios of branching fractions R(D∗)\mathcal{R}(D^{*}) and R(D0)\mathcal{R}(D^{0})

The ratios of branching fractions $\mathcal{R}(D^{*})\equiv\mathcal{B}(\bar{B}\to D^{*}\tau^{-}\bar{\nu}_{\tau})/\mathcal{B}(\bar{B}\to D^{*}\mu^{-}\bar{\nu}_{\mu})$ and $\mathcal{R}(D^{0})\equiv\mathcal{B}(B^{-}\to D^{0}\tau^{-}\bar{\nu}_{\tau})/\mathcal{B}(B^{-}\to D^{0}\mu^{-}\bar{\nu}_{\mu})$ are measured, assuming isospin symmetry, using a sample of proton-proton collision data corresponding to 3.0 fb${ }^{-1}$ of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode $\tau^{-}\to\mu^{-}\nu_{\tau}\bar{\nu}_{\mu}$. The measured values are $\mathcal{R}(D^{*})=0.281\pm0.018\pm0.024$ and $\mathcal{R}(D^{0})=0.441\pm0.060\pm0.066$, where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is $\rho=-0.43$. Results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the Standard Model.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-039.html (LHCb public pages

Soil macrofauna communities in Brazilian land-use systems

Soil animal communities include more than 40 higher-order taxa, representing over 23% of all described species. These animals have a wide range of feeding sources and contribute to several important soil functions and ecosystem services. Although many studies have assessed macroinvertebrate communities in Brazil, few of them have been published in journals and even fewer have made the data openly available for consultation and further use. As part of ongoing efforts to synthesise the global soil macrofauna communities and to increase the amount of openly-accessible data in GBIF and other repositories related to soil biodiversity, the present paper provides links to 29 soil macroinvertebrate datasets covering 42 soil fauna taxa, collected in various land-use systems in Brazil. A total of 83,085 georeferenced occurrences of these taxa are presented, based on quantitative estimates performed using a standardised sampling method commonly adopted worldwide to collect soil macrofauna populations, i.e. the TSBF (Tropical Soil Biology and Fertility Programme) protocol. This consists of digging soil monoliths of 25 x 25 cm area, with handsorting of the macroinvertebrates visible to the naked eye from the surface litter and from within the soil, typically in the upper 0-20 cm layer (but sometimes shallower, i.e. top 0-10 cm or deeper to 0-40 cm, depending on the site). The land-use systems included anthropogenic sites managed with agricultural systems (e.g. pastures, annual and perennial crops, agroforestry), as well as planted forests and native vegetation located mostly in the southern Brazilian State of Paraná (96 sites), with a few additional sites in the neighbouring states of São Paulo (21 sites) and Santa Catarina (five sites). Important metadata on soil properties, particularly soil chemical parameters (mainly pH, C, P, Ca, K, Mg, Al contents, exchangeable acidity, Cation Exchange Capacity, Base Saturation and, infrequently, total N), particle size distribution (mainly % sand, silt and clay) and, infrequently, soil moisture and bulk density, as well as on human management practices (land use and vegetation cover) are provided. These data will be particularly useful for those interested in estimating land-use change impacts on soil biodiversity and its implications for below-ground foodwebs, ecosystem functioning and ecosystem service delivery.Quantitative estimates are provided for 42 soil animal taxa, for two biodiversity hotspots: the Brazilian Atlantic Forest and Cerrado biomes. Data are provided at the individual monolith level, representing sampling events ranging from February 2001 up to September 2016 in 122 sampling sites and over 1800 samples, for a total of 83,085 ocurrences

A year of genomic surveillance reveals how the SARS-CoV-2 pandemic unfolded in Africa.

The progression of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic in Africa has so far been heterogeneous, and the full impact is not yet well understood. In this study, we describe the genomic epidemiology using a dataset of 8746 genomes from 33 African countries and two overseas territories. We show that the epidemics in most countries were initiated by importations predominantly from Europe, which diminished after the early introduction of international travel restrictions. As the pandemic progressed, ongoing transmission in many countries and increasing mobility led to the emergence and spread within the continent of many variants of concern and interest, such as B.1.351, B.1.525, A.23.1, and C.1.1. Although distorted by low sampling numbers and blind spots, the findings highlight that Africa must not be left behind in the global pandemic response, otherwise it could become a source for new variants

Expression of genes involved in key metabolic processes during winter flounder (Pseudopleuronectes americanus) metamorphosis

L’étude avait pour but d’établir une meilleure compréhension des évènements moléculaires qui régissent l’ontogénèse chez la plie rouge (Pseudopleuronectes americanus (Walbaum, 1792)). L’expression de sept gènes intervenant dans des processus métaboliques clés durant la métamorphose a été mesurée au moment de la déposition (S0) et après 15 (S15) et 30 (S30) jours suivant cette dernière, et comparée à celle de larves pélagiques avant la déposition (PL). Deux stades critiques ont été cernés : (1) la transition des larves de l’habitat pélagique à l’habitat benthique (de PL à S0) et (2) la maturation de métamorphose, durant laquelle la larve demeure déposée sans croître (de S0 à S30). L’expression génique de l’hormone de croissance (gh) a augmenté de manière significative à S0. À S30, une augmentation de l’expression génique de la cytochrome oxydase (cox) a eu lieu, de concert avec une deuxième augmentation de l’expression génique de la gh, ce qui laisse croire qu’une capacité aérobie accrue supportait la croissance avant la baisse de température automnale. Les patrons d’expression des gènes de la pyruvate kinase (pk), de la glucose-6-phosphate déshydrogénase (g6pd) et de la lipase stimulée par les sels biliaires (bal) indiquaient que la synthèse énergétique pourrait être principalement assurée par la glycolyse au stade PL, par la voie pentose–phosphate à la déposition et par le métabolisme des lipides à S30. L’expression des gènes de la protéine de choc thermique 70 (hsp70), de la superoxyde dismutase (sod), de la cox et de la peroxyrédoxine-6 (prx6) a révélé que le stress oxydatif et le développement d’une protection anti-oxydation en découlant étaient limités durant le stade PL, renforcés à la déposition et très élevés à S30, sans doute en raison du taux de croissance accru observé à cette période. -- Mots-clés : métamorphose ; hormone de croissance ; enzymes antioxydantes ; métabolisme énergétique ; plie rouge ; Pseudopleuronectes americanus

Plasticity in the link between oxygen consumption and ATP production and its relevance for animal lifehistory.

International audienc

Characterization and modulation of gene expression and enzymatic activity of delta-6 desaturase in teleosts : a review

International audienceThere is currently considerable interest in understanding how the biosynthetic pathways of highly unsaturated fatty acids (HUFA) are regulated in fish. The aim is to know if it is possible to replace fish oils (FO), rich in HUFA, by vegetable oils (VO), poor in HUFA and rich in their 18 carbon fatty acid precursors, in the feed of cultured fish species of commercial importance. Thus many studies have focussed on delta-6 desaturase (Delta 6D) since it is the rate-limiting enzyme involved in HUFA biosynthesis from precursors. The aims of this paper were (i) to review and compare the structure, function, and tissue distribution of the Delta 6D gene in teleosts and (ii) to review the effect of nutrition and environment on the modulation of Delta 6D gene expression and on the activity of this enzyme in teleosts. Most existing studies have clearly shown that Delta 6D is modulated by nutrition and environment in freshwater fish. This modulation allows the control of lipid metabolism and the maintenance of cell membrane functionality. Delta 6D gene expression and enzymatic activity were higher in fish fed VO diets than in those fed FO diets, irrespective of their life cycle in seawater or freshwater; this concurs with expectations regarding the compensation for HUFA deficiency in VO. However, the magnitude of these increases was not great enough to maintain HUFA tissue content. Such a decrease in tissue content may result either from competition between substrates for Delta 6D or from the inhibition of subsequent steps in HUFA biosynthesis, such as elongation or delta-5 desaturation activity. Other studies showed that Delta 6D enzyme activity is stimulated at low temperatures and low salinities, which keep cell membranes fluid. In salmonids, Delta 6D would then play an important role in the adaptation to salinity changes at parr-smolt transformation. In marine fish, similar nutritional and environmental modulations may occur, although conflicting data exist. A low expression of the Delta 6D gene or the involvement of genetic, environmental, or hormonal factors could explain why Delta 6D appears to be barely functional in marine fish. This review shows that, despite the large number of studies investigating the regulation of Delta 6D, little is known about the molecular mechanisms involved. Furthermore, the nutritional and environmental regulation of other enzymes involved in HUFA biosynthesis still need to be investigated to obtain a better understanding of the regulation of HUFA biosynthetic pathways in teleosts, ultimately leading to improvements in fish production