Pif1 Helicase Lengthens Some Okazaki Fragment Flaps Necessitating Dna2 Nuclease/Helicase Action in the Two-nuclease Processing Pathway

We have developed a system to reconstitute all of the proposed steps of Okazaki fragment processing using purified yeast proteins and model substrates. DNA polymerase δ was shown to extend an upstream fragment to displace a downstream fragment into a flap. In most cases, the flap was removed by flap endonuclease 1 (FEN1), in a reaction required to remove initiator RNA in vivo. The nick left after flap removal could be sealed by DNA ligase I to complete fragment joining. An alternative pathway involving FEN1 and the nuclease/helicase Dna2 has been proposed for flaps that become long enough to bind replication protein A (RPA). RPA binding can inhibit FEN1, but Dna2 can shorten RPA-bound flaps so that RPA dissociates. Recent reconstitution results indicated that Pif1 helicase, a known component of fragment processing, accelerated flap displacement, allowing the inhibitory action of RPA. In results presented here, Pif1 promoted DNA polymerase δ to displace strands that achieve a length to bind RPA, but also to be Dna2 substrates. Significantly, RPA binding to long flaps inhibited the formation of the final ligation products in the reconstituted system without Dna2. However, Dna2 reversed that inhibition to restore efficient ligation. These results suggest that the two-nuclease pathway is employed in cells to process long flap intermediates promoted by Pif1

Issue des accouchements sur utérus cicatriciel dans un hôpital universitaire au Burkina

Certains auteurs ont tendance à privilégier la césarienne comme méthode de prise en charge d’une parturiente porteuse d’un utérus cicatriciel.D’autres auteurs préconisent un accouchement par voie basse quand des paramètres cliniques précis sont observés. Le but de cette étude estd’analyser la prise en charge et l’issue des accouchements sur utérus cicatriciel au Centre Hospitalier Universitaire Souro Sanou de Bobo-Dioulasso et de la comparer aux différentes approches recommandées. Nous avons menés une étude transversale dans le Département de Gynécologie d’Obstétrique et de Médecine de la Reproduction du Centre Hospitalier Universitaire Sanou Souro de Bobo Dioulasso du 1er août 2006 au 1er août 2007 et a concerné 252 parturientes ayant un utérus cicatriciel parmi 4256 accouchements déroulés pendant la même période. Les accouchements sur utérus cicatriciels ont représenté 5,92 % de l’ensemble des accouchements dans notre département. La moyenne d'âge des patientes était de 26,2 ans et la parité moyenne de 4,3. Une césarienne d’emblée a été pratiquée chez 44% des parturientes ayant un utérus cicatriciel et 56 % parmi elles ont fait l'objet d'une épreuve utérine. Sur l’ensemble des épreuves utérines, 61% des parturientes ont accouché par voie basse. La mortalité maternelle était nulle et La mortalité périnatale était relativement importante. Les conditions d’acceptabilité de la voie basse ont été les mêmes chez toutes les patientes et un check liste a été proposé pour une meilleure prise en charge. L'épreuve utérine en salle d’accouchement doit être la règle à chaque fois que cela est possible chez une parturiente porteuse d’utérus cicatriciel. L’établissement d’un check liste pour accouchement par voie basse sur utérus cicatriciel facilite les prises de décision.Key words: Utérus cicatriciels, épreuve utérine, accouchement par voie basse, check-lis

Characterization of woody roots located in dikes by near-infrared spectroscopy and chemometrics

International audienceThe decomposition of tree stump and roots is highly detrimental for the safety of dikes. Root decomposition in the fills generates significant risks, particularly a risk of internal erosion by piping. In order to characterize root decomposition and assess decomposition rate, root samples were buried in experimental site. The Near-Infrared spectroscopy (NIR) and analysis of the spectral data by chemometric tools, allowed distinguishing and predicting decomposition times, tree species and root diameters

An Alternative Pathway for Okazaki Fragment Processing - Resolution of Fold-Back Flaps by Pif1 Helicase

Two pathways have been proposed for eukaryotic Okazaki fragment RNA primer removal. Results presented here provide evidence for an alternative pathway. Primer extension by DNA polymerase δ (pol δ) displaces the downstream fragment into an RNA-initiated flap. Most flaps are cleaved by flap endonuclease 1 (FEN1) while short, and the remaining nicks joined in the first pathway. A small fraction escapes immediate FEN1 cleavage and is further lengthened by Pif1 helicase. Long flaps are bound by replication protein A (RPA), which inhibits FEN1. In the second pathway, Dna2 nuclease cleaves an RPA-bound flap and displaces RPA, leaving a short flap for FEN1. Pif1 flap lengthening creates a requirement for Dna2. This relationship should not have evolved unless Pif1 had an important role in fragment processing. In this study, biochemical reconstitution experiments were used to gain insight into this role. Pif1 did not promote synthesis through GC-rich sequences, which impede strand displacement. Pif1 was also unable to open fold-back flaps that are immune to cleavage by either FEN1 or Dna2 and cannot be bound by RPA. However, Pif1 working with pol δ readily unwound a full-length Okazaki fragment initiated by a fold-back flap. Additionally, a fold-back in the template slowed pol δ synthesis, so that the fragment could be removed before ligation to the lagging strand. These results suggest an alternative pathway in which Pif1 removes Okazaki fragments initiated by fold-back flaps in vivo

Otomastoïdites aiguës dans le Service d’ORL du CHU Yalgadode Ouagadougou: à propos de 44 cas

Analyser les aspects diagnostiques et thérapeutiques des otomastoïdites dans le Service d’ORL du CHU-YO de Ouagadougou. Méthode : Il s’est agit d’une étude rétrospective de 10 ans, qui a porté sur 44 cas. Résultats: l’incidence annuelle était de 4,4 cas et l’âge moyen de 13,41 ans. Les mastoïdites étaient majoritairement fistulisées (59,09%) et les principaux germes incriminés étaient Staphylococcus aureus (35,29%), Proteus mirabilis (23,53%) et Pseudomonas aeruginosa (23,53%). Ils étaient surtout sensibles à la ciprofloxacine (82,35%) et la ceftriaxone (58,82%). Le traitement a été médico-chirurgical dans 86,36% des cas et l’évolution favorable dans 72,73%. Douze cas (27,27%) de décès par complication systémique et endocrânienne ont été enregistrés. Conclusion : Il convient de prioriser les mesures préventives et la prise en charge précoce des otites infectieuses.Mots clés: Otomastoïdite, épidémiologie, diagnostic, thérapeutique

Risk factors associated with HIV prevalence in pregnant women in Burkina Faso, from 2006 to 2014

Purpose of the study: To determine the socio-demographic factors influencing the dynamics of HIV prevalence among pregnant women in Burkina Faso.Material and methods: A total of 66,597 pregnant women from the 13 health regions of Burkina Faso were included in this study conducted between 2006 and 2014. Venous blood samples were collected and analyzed for the detection of HIV antibodies according to WHO / UNAIDS strategy II, using the mixed test Vironostika HIV Uniform II Plus O (Bio-Mérieux) and the test discriminating ImmunoCombII HIV-1 & 2 BiSpot (Orgenics). Samples with discordant results between the two tests, as well as those positive to HIV-2 or HIV-1 + 2, were retested with HIV BLOT 2.2 (MP Diagnostics). Sociodemographic data collected from the participants were correlated with their HIV status to determine key risk factors influencing HIV infection prevalence in Burkina Faso.Results: Sociodemographic data showed that the study population consisted mainly of married women (91.2%) at their first pregnancy (27.1%) with a large majority of them being housewives (86.2%) who did not attend any form of schooling (69.4%). About 88.4% had stayed longer than a year in the health region where they initially participated in the study and 55.8% were between 20 and 29 years of age. Overall HIV prevalence significantly dropped from 2.7 % in 2006 to 1.3% in 2014. However HIV seroprevalence in this study has varied significantly according to socio-demographic characteristics including marital status, parity, occupation, education, age group and the length of stay in the women's health community (p <0.0001). Factors sustaining HIV transmission included the status of being unmarried (OR=1.67 [1.42-1.97]), primigest (OR=1.64 [1.41-1.89]), having other occupations except being student (OR = 1.68 [1.20-2.33]), aged between 20-49 years (OR=3.14 [2.51-3.93]) and the duration of stay less than a year in their locality (OR=5.33 [4.61-10.16]) and these factors were identified as main risk factors associated with HIV prevalence.Conclusion: Burkina Faso remains among the countries with concentrated epidemics despite a significant reduction in the prevalence observed in this study. The inclusion of identified risk factors in the national HIV program could improve the quality of the response to the epidemic.Keywords: HIV-Pregnant Women-Risk Factors-Burkina Fas

Macrophage tropism of HIV-1 depends on efficient cellular dNTP utilization by reverse transcriptase

Retroviruses utilize cellular dNTPs to perform proviral DNA synthesis in infected host cells. Unlike oncoretroviruses, which replicate in dividing cells, lentiviruses, such as human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus, are capable of efficiently replicating in non-dividing cells (terminally differentiated macrophages) as well as dividing cells (i.e. activated CD4+ T cells). In general, non-dividing cells are likely to have low cellular dNTP content compared with dividing cells. Here, by employing a novel assay for cellular dNTP content, we determined the dNTP concentrations in two HIV-1 target cells, macrophages and activated CD4+ T cells. We found that human macrophages contained 130-250-fold lower dNTP concentrations than activated human CD4+ T cells. Biochemical analysis revealed that, unlike oncoretroviral reverse transcriptases (RTs), lentiviral RTs efficiently synthesize DNA even in the presence of the low dNTP concentrations equivalent to those found in macrophages. In keeping with this observation, HIV-1 vectors containing mutant HIV-1 RTs, which kinetically mimic oncoretroviral RTs, failed to transduce human macrophages despite retaining normal infectivity for activated CD4+ T cells and other dividing cells. These results suggest that the ability of HIV-1 to infect macrophages, which is essential to establishing the early pathogenesis of HIV-1 infection, depends, at least in part, on enzymatic adaptation of HIV-1 RT to efficiently catalyze DNA synthesis in limited cellular dNTP substrate environments

Characterizing cassava farmer typologies and their seed sourcing practices to explore opportunities for economically sustainable seed business models in Rwanda

Open Access Article; Published online: 30 Nov 2021The overdependency on local cassava varieties and informal seed sources by farmers in Rwanda has contributed to the spread of cassava viral diseases. The use of improved planting materials made available through formal seed sources, that assure seed quality, is one way to prevent future disease outbreaks. In order to increase the availability of, and farmers access to, such materials there is increasing interest to develop seed business models. This study aims to understand seed sourcing practices of different farm typologies to inform the development of tailored seed business models. A total of 390 farmers were interviewed and the collected data was analyzed into clusters, resulting in seven farm typologies. Seed sourcing strategies, seed replacement dynamics and purchasing behavior of these typologies were explored via a seed tracing study. We find that more commercial oriented farmers have better access to formal seed sources. Nevertheless, the majority of farmers in all typologies accessed new varieties and quality cassava seed via informal channels. At both formal and informal sources, cash investments in seed were mainly made by the categories of better-off farmers, and were one-time investments to acquire a new variety. Based on farmers current seed sourcing practices, clarifications on the differences between farmers and their willingness-to-pay, the roles of seed degeneration, cost-benefit analysis, value propositions and profit formulas seem important requirements for the further development of viable cassava seed business models. We conclude that tailoring seed business models can have a high potential as it acknowledges differences among farmers, but that careful coordination is needed to ensure that one approach or intervention does not contrast with and/or undermine the others

Level of Concordance of Pre-, Intra-, and Postoperative Staging in Cervical Cancers (TREYA Study)

Concomitant radiochemotherapy is the therapeutic standard for locally advanced (Ib2 to IVa stage FIGO) cervical cancer. In the absence of a radiotherapy in many of our Sub-Saharan African countries, surgical resection is the only therapeutic method available in hopes of achieving a definite cure. However, criteria for curative surgery are not always met due to preoperative understaging of most of our patients. In addition to socioeconomic factors, the causes for understaging are numerous. These include the lack of personnel or underqualified personnel and the absence of complete workup to assess the resectability of the tumor, but above all the lack of decision-making through multidisciplinary consultation meetings. This study makes a plea in order to provide our hospitals with qualified personnel and adequate technical platform to allow efficient management of our patients with cervical cancer

Contributions of the two accessory subunits, RNASEH2B and RNASEH2C, to the activity and properties of the human RNase H2 complex

Eukaryotic RNase H2 is a heterotrimeric enzyme. Here, we show that the biochemical composition and stoichiometry of the human RNase H2 complex is consistent with the properties previously deduced from genetic studies. The catalytic subunit of eukaryotic RNase H2, RNASEH2A, is well conserved and similar to the monomeric prokaryotic RNase HII. In contrast, the RNASEH2B and RNASEH2C subunits from human and Saccharomyces cerevisiae share very little homology, although they both form soluble B/C complexes that may serve as a nucleation site for the addition of RNASEH2A to form an active RNase H2, or for interactions with other proteins to support different functions. The RNASEH2B subunit has a PIP-box and confers PCNA binding to human RNase H2. Unlike Escherichia coli RNase HII, eukaryotic RNase H2 acts processively and hydrolyzes a variety of RNA/DNA hybrids with similar efficiencies, suggesting multiple cellular substrates. Moreover, of five analyzed mutations in human RNASEH2B and RNASEH2C linked to Aicardi-Goutières Syndrome (AGS), only one, R69W in the RNASEH2C protein, exhibits a significant reduction in specific activity, revealing a role for the C subunit in enzymatic activity. Near-normal activity of four AGS-related mutant enzymes was unexpected in light of their predicted impairment causing the AGS phenotype