Surveillance des patients sous AVK : les laboratoires s’impliquent

Un accord a été signé pour un meilleur suivi des patients sous antivitamine K (AVK) entre les syndicats de biologie libérale et la CNAM dans l’avenant à la convention nationale paru au Journal Officiel du 27 février 2003⋆. Le Pr Ludovic Drouet⋆⋆ nous fait part de sa réaction et de ses attentes suite à cet engagement de la profession.     

Alterations in Peripheral Blood B Cell Subsets and Dynamics of B Cell Responses during Human Schistosomiasis

Antibody responses are thought to play an important role in control of Schistosoma infections, yet little is known about the phenotype and function of B cells in human schistosomiasis. We set out to characterize B cell subsets and B cell responses to B cell receptor and Toll-like receptor 9 stimulation in Gabonese schoolchildren with Schistosoma haematobium infection. Frequencies of memory B cell (MBC) subsets were increased, whereas naive B cell frequencies were reduced in the schistosome-infected group. At the functional level, isolated B cells from schistosome-infected children showed higher expression of the activation marker CD23 upon stimulation, but lower proliferation and TNF-α production. Importantly, 6-months after 3 rounds of praziquantel treatment, frequencies of naive B cells were increased, MBC frequencies were decreased and with the exception of TNF-α production, B cell responsiveness was restored to what was seen in uninfected children. These data show that S. haematobium infection leads to significant changes in the B cell compartment, both at the phenotypic and functional level.     

Rhodamine B as a collective marker for studying movements of small mammals

We present a new method of collective marking (rhodamine B) of small mammals that can be used under natural conditions. We examine the acceptance of marked baits, detection and persistence of the signal on the different kinds of hairs of two small species of rodents. Rhodamine B was ingested by captive animals and their hairs were dyed a fluorescent red coloration and observed over more than 150 days. Preliminary results obtained under field conditions tend to demonstrate that winter and summer movements could be detected by this technique. This new collective marking technique may be of great interest to study population turnover and movements of small mammals between habitat patches; it may represent an important method of assessing connectivity and permeability of landscapes by small mammals.     

Real-life Lernaean Hydras: a practical activity about the effects of oxygen concentration on regenerative capabilities of planarians

ABSTRACT

Changes in environmental conditions can have a profound impact on organismal processes. For aquatic organisms, changes in dissolved oxygen concentration can have major repercussions, notably for physiological processes that have high long-term energetic costs and are more likely to rely on aerobic metabolic pathways. Here we propose a simple college or university-level low-cost laboratory activity that addresses the effect of differences in oxygen concentration on an important physiological property of planarian flatworms: their regeneration capacity. Students were asked to perform measurements and statistically compare the efficacy of the regeneration process between planarians kept in normoxic conditions and others kept in hypoxic conditions. The activity was evaluated by asking students to produce a short laboratory report with all of the sections that a scientific article generally comprises. This hands-on experiment has the benefit of going beyond how planarians are traditionally used in biodiversity classes (i.e. basic anatomy of flatworms) by combining behavioural, physiological and environmental observations while investigating the effects of an environmental variable on the regeneration response. We would further encourage professors to expand even more upon this framework by providing the students with an opportunity to actively engage in all steps inherent to the scientific process.     

13C-chloromethane incubations provide evidence for novel bacterial chloromethane degraders in a living tree fern

Chloromethane (CH₃Cl) is the most abundant halogenated volatile organic compound in the atmosphere and contributes to stratospheric ozone depletion. CH₃Cl has mainly natural sources such as emissions from vegetation. In particular, ferns have been recognized as strong emitters. Mitigation of CH₃Cl to the atmosphere by methylotrophic bacteria, a global sink for this compound, is likely underestimated and remains poorly characterized. We identified and characterized CH₃Cl-degrading bacteria associated with intact and living tree fern plants of the species Cyathea australis by stable isotope probing (SIP) with ¹³C-labelled CH₃Cl combined with metagenomics. Metagenome-assembled genomes (MAGs) related to Methylobacterium and Friedmanniella were identified as being involved in the degradation of CH₃Cl in the phyllosphere, i.e., the aerial parts of the tree fern, while a MAG related to Sorangium was linked to CH₃Cl degradation in the fern rhizosphere. The only known metabolic pathway for CH₃Cl degradation, via a methyltransferase system including the gene cmuA, was not detected in metagenomes or MAGs identified by SIP. Hence, a yet uncharacterized methylotrophic cmuA-independent pathway may drive CH₃Cl degradation in the investigated tree ferns.     

Roe deer on ice: Selection despite limited effective population size through the Pleistocene

Roe deer (Capreolus spp.) are a little odd. They are one of only a few placental mammals—and the only genus among even‐toed ungulates—capable of putting embryonic development “on ice”, also known as embryonic diapause (Figure 1). It would seem such an unusual trait is probably the product of natural selection, but a big question is, how does selection for important traits, such as diapause, interact with the historical demography of a species? In a ‘From the Cover’ article in this issue of Molecular Ecology, de Jong et al. (2020) demonstrate that selection is acting on genes associated with reproductive biology in roe deer, despite heightened genetic drift due to reduced effective population size through the Pleistocene.     

Secondary structure and NMR resonance assignments of the C-terminal DNA-binding domain of Uup protein

ATP-binding cassette (ABC) systems belong to a large superfamily of proteins that couple the energy released from ATP hydrolysis to a wide variety of cellular processes, including not only transport of various molecules, but also gene regulation, and DNA repair. Mutations in the bacterial uup gene, which encodes a cytosolic ABC ATPase, lead to an increase in the frequency of precise excision of transposons Tn10 and Tn5, suggesting a role of the Uup protein in DNA metabolism. Uup is a 72?kDa polypeptide which comprises two ABC domains, separated by a 75-residue linker, and a C-terminal domain (CTD) of unknown function. The Uup protein from Escherichia coli has been shown to bind DNA in vitro, and the CTD domain contributes to the DNA-binding affinity. We have produced and purified uniformly labeled ¹⁵N- and ¹⁵N/¹³C Uup CTD domain (region 528?C635), and assigned backbone and side-chains resonances using heteronuclear NMR spectroscopy. Secondary structure evaluation based on backbone chemical shifts is consistent with the presence of three ??-helices, including two long ones (residues 564?C590 and 601?C632), suggesting that Uup CTD may fold as an intramolecular coiled coil motif. This work provides the starting point towards determining the first atomic structure of a non-ATPase domain within the vast REG subfamily of ABC soluble ATPases.