Meiotic Maturation of the Mouse Oocyte Requires an Equilibrium between Cyclin B Synthesis and Degradation

AbstractAmong the proteins whose synthesis and/or degradation is necessary for a proper progression through meiotic maturation, cyclin B appears to be one of the most important. Here, we attempted to modulate the level of cyclin B1 and B2 synthesis during meiotic maturation of the mouse oocyte. We used cyclin B1 or B2 mRNAs with poly(A) tails of different sizes and cyclin B1 or B2 antisense RNAs. Oocytes microinjected with cyclin B1 mRNA showed two phenotypes: most were blocked in MI, while the others extruded the first polar body in advance when compared to controls. Moreover, these effects were correlated with the length of the poly(A) tail. Thus it seems that the rate of cyclin B1 translation controls the timing of the first meiotic M phase and the transition to anaphase I. Moreover, overexpression of cyclin B1 or B2 was able to bypass the dbcAMP-induced germinal vesicle block, but only the cyclin B1 mRNA-microinjected oocytes did not extrude their first polar body. Oocytes injected with the cyclin B1 antisense progressed through the first meiotic M phase but extruded the first polar body in advance and were unable to enter metaphase II. This suggested that inhibition of cyclin B1 synthesis only took place at the end of the first meiotic M phase, most likely because the cyclin B1 mRNA was protected. The injection of cyclin B2 antisense RNA had no effect. The life observation of the synthesis and degradation of a cyclin B1–GFP chimera during meiotic maturation of the mouse oocyte demonstrated that degradation can only occur during a given period of time once it has started. Taken together, our data demonstrate that the rates of cyclin B synthesis and degradation determine the timing of the major events taking place during meiotic maturation of the mouse oocyte

When Hypereosinophilia Leads to Stroke

AFIP1L1-PDGFRA fusion can only be confirmed through molecular and cytogenetic investigations causing a delay in the diagnosis. However, patients with this mutation need urgent treatment because they present hypereosinophilia which may be associated with short-term tissue damage. Thromboembolism is a known cause of death in hypereosinophilic syndrome. A case of Loeffler endocarditis due to FIP1L1-PDGFRA-associated chronic eosinophilic leukemia presenting hemiparesis with fever, which also mislead the initial diagnosis, is reported

CYP52X1, representing new cytochrome P450 subfamily, displays fatty acid hydroxylase activity and contributes to virulence and growth on insect cuticular substrates in entomopathogenic fungus Beauveria bassiana

Infection of insects by the entomopathogenic fungus Beauveria bassiana proceeds via attachment and penetration of the host cuticle. The outermost epicuticular layer or waxy layer of the insect represents a structure rich in lipids including abundant amounts of hydrocarbons and fatty acids. A member of a novel cytochrome P450 subfamily, CYP52X1, implicated in fatty acid assimilation by B. bassiana was characterized. B. bassiana targeted gene knockouts lacking Bbcyp52x1 displayed reduced virulence when topically applied to Galleria mellonella, but no reduction in virulence was noted when the insect cuticle was bypassed using an intrahemoceol injection assay. No significant growth defects were noted in the mutant as compared with the wild-type parent on any lipids substrates tested including alkanes and fatty acids. Insect epicuticle germination assays, however, showed reduced germination of ΔBbcyp52x1 conidia on grasshopper wings as compared with the wild-type parent. Complementation of the gene-knock with the full-length gene restored virulence and insect epicuticle germination to wild-type levels. Heterologous expression of CYP52X1 in yeast was used to characterize the substrate specificity of the enzyme. CYP52X1 displayed the highest activity against midrange fatty acids (C12:0 and C14:0) and epoxy stearic acid, 4–8-fold lower activity against C16:0, C18:1, and C18:2, and little to no activity against C9:0 and C18:0. Analyses of the products of the C12:0 and C18:1 reactions confirmed NADPH-dependent regioselective addition of a terminal hydroxyl to the substrates (ω-hydroxylase). These data implicate CYP52X1 as contributing to the penetration of the host cuticle via facilitating the assimilation of insect epicuticle lipids.Fil: Zhang, Shizhu. Nanjing Normal University; China. University of Florida; Estados UnidosFil: Widemann, Emilie. Université de Strasbourg; FranciaFil: Bernard, Grausem. Université de Strasbourg; FranciaFil: Lesot, Agnes. Université de Strasbourg; FranciaFil: Pinot, Franck. Université de Strasbourg; FranciaFil: Pedrini, Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner". Universidad Nacional de la Plata. Facultad de Ciencias Médicas. Instituto de Investigaciones Bioquímicas de La Plata "Prof. Dr. Rodolfo R. Brenner"; ArgentinaFil: Keyhani, Nemat O.. University of Florida; Estados Unido

Rotating disk electrodes to assess river biofilm thickness and elasticity

The present study examined the relevance of an electrochemical method based on a rotating disk electrode (RDE) to assess river biofilm thickness and elasticity. An in situ colonisation experiment in the River Garonne (France) in August 2009 sought to obtain natural river biofilms exhibiting differentiated architecture. A constricted pipe providing two contrasted flow conditions (about 0.1 and 0.45 m s−1 in inflow and constricted sections respectively) and containing 24 RDE was immersed in the river for 21 days. Biofilm thickness and elasticity were quantified using an electrochemical assay on 7 and 21 days old RDE-grown biofilms (t7 and t21, respectively). Biofilm thickness was affected by colonisation length and flow conditions and ranged from 36 ± 15 μm (mean ± standard deviation, n = 6) in the fast flow section at t7 to 340 ± 140 μm (n = 3) in the slow flow section at t21. Comparing the electrochemical signal to stereomicroscopic estimates of biofilms thickness indicated that the method consistently allowed (i) to detect early biofilm colonisation in the river and (ii) to measure biofilm thickness of up to a few hundred μm. Biofilm elasticity, i.e. biofilm squeeze by hydrodynamic constraint, was significantly higher in the slow (1300 ± 480 μm rpm1/2, n = 8) than in the fast flow sections (790 ± 350 μm rpm1/2, n = 11). Diatom and bacterial density, and biofilm-covered RDE surface analyses (i) confirmed that microbial accrual resulted in biofilm formation on the RDE surface, and (ii) indicated that thickness and elasticity represent useful integrative parameters of biofilm architecture that could be measured on natural river assemblages using the proposed electrochemical method

Meiotic spindle stability depends on MAPK-interacting and spindle-stabilizing protein (MISS), a new MAPK substrate

Vertebrate oocytes arrest in the second metaphase of meiosis (metaphase II [MII]) by an activity called cytostatic factor (CSF), with aligned chromosomes and stable spindles. Segregation of chromosomes occurs after fertilization. The Mos/…/MAPK (mitogen-activated protein kinases) pathway mediates this MII arrest. Using a two-hybrid screen, we identified a new MAPK partner from a mouse oocyte cDNA library. This protein is unstable during the first meiotic division and accumulates only in MII, where it localizes to the spindle. It is a substrate of the Mos/…/MAPK pathway. The depletion of endogenous RNA coding for this protein by three different means (antisense RNA, double-stranded [ds] RNA, or morpholino oligonucleotides) induces severe spindle defects specific to MII oocytes. Overexpressing the protein from an RNA not targeted by the morpholino rescues spindle destabilization. However, dsRNA has no effect on the first two mitotic divisions. We therefore have discovered a new MAPK substrate involved in maintaining spindle integrity during the CSF arrest of mouse oocytes, called MISS (for MAP kinase–interacting and spindle-stabilizing protein)

Impact of cone-beam computed tomography for the identification and management of an oral portal of entry in patients with infective endocarditis. A Delphi study

Infective endocarditis (IE) is a rare and life-threatening disease. Cutaneous portal of entry (POE) is predominant for IE, but an oral POE is the second most frequent source. Thus looking for and treating an oral POE in IE patients is of critical importance in order to reduce the risk of IE relapse or recurrence. The objectives of this study were: 1) To reach a consensus on decision-making following the detection of an oral POE on cone-beam computed tomography (CBCT) while they were not identified using the current recommended approach in IE patients (oral examination and orthopantomogram: OPT). 2) To determine whether this consensus differs when regarding the microbiology of IE. Twenty oral or maxillofacial surgeons participated to this Delphi study. The questionnaire was based on five radiological cases (OPT and matching CBCT) with two scenarios according to the objectives of detecting oral POE in an IE patient (curative in case of oral causative microorganism, and preventive if not) and different therapeutic approaches (surgical or conservative treatment, no treatment) for each of them. Consensus was defined as an agreement rate of ?75%. The response rate was?85%. After four rounds, consensus was achieved for all proposals. CBCT changed the decision-making of experts in four cases. In one case, the decision was influenced by the IE microbiology toward a more radical approach in case of oral causative microorganism. In IE patients, CBCT changed markedly the decision-making of experts by eradicating more oral POE than when using OPT. This could reduce the risk of IE relapse and recurrence

The Key Role of Epigenetics in the Persistence of Asexual Lineages

Asexual organisms, often perceived as evolutionary dead ends, can be long-lived and geographically widespread. We propose that epigenetic mechanisms could play a crucial role in the evolutionary persistence of these lineages. Genetically identical organisms could rely on phenotypic plasticity to face environmental variation. Epigenetic modifications could be the molecular mechanism enabling such phenotypic plasticity; they can be influenced by the environment and act at shorter timescales than mutation. Recent work on the asexual vertebrate Chrosomus eos-neogaeus (Pisces: Cyprinidae) provides broad insights into the contribution of epigenetics in genetically identical individuals. We discuss the extension of these results to other asexual organisms, in particular those resulting from interspecific hybridizations. We finally develop on the evolutionary relevance of epigenetic variation in the context of heritability