Asynchronous spore germination in isogenic natural isolates of Saccharomyces paradoxus

Spores from wild yeast isolates often show great variation in the size of colonies they produce, for largely unknown reasons. Here we measure the colonies produced from single spores from six different wild Saccharomyces paradoxus strains. We found remarkable variation in spore colony sizes, even among spores that were genetically identical. Different strains had different amounts of variation in spore colony sizes, and variation was not affected by the number of preceding meioses, or by spore maturation time. We used time-lapse photography to show that wild strains also have high variation in spore germination timing, providing a likely mechanism for the variation in spore colony sizes. When some spores from a laboratory strain make small colonies, or no colonies, it usually indicates a genetic or meiotic fault. Here, we demonstrate that in wild strains spore colony size variation is normal. We discuss and assess potential adaptive and non-adaptive explanations for this variation

Recherche des facteurs les plus influents sur le rendement et la qualité de l’agar- agar de la rhodophycée Gelidium spinosum (S.G. Gmelin) P.C. Silva

Cinq (5) facteurs physico-chimiques : concentration en carbonate de sodium, température et durée de carbonatation, temps de digestion et pression, ont été étudiés simultanément pour voir leur effet sur l’extrait d’agar de Gelidium spinosum. L’étude a mis en évidence l’influence plus ou moins importante dechacun de ces facteurs sur les réponses recherchées (rendement d’extraction, force de gel, point de gélification et point de fusion). Différentes interactions plus ou moins importantes ont pu être également mises en évidence entre les facteurs étudiés.Mots-clés : gelidium spinosum, facteurs influents, interactions, agar-agar, rendement, qualité

Nanobiopesticides: Silica nanoparticles with spiky surfaces enable dual adhesion and enhanced performance

Biopesticides, such as spinosad, are a new-generation of ecofriendly pesticides in livestock industry. However, spinosad suffers from short duration of effectiveness and low potency in field conditions. Herein we report the development of a new nanospinosad design with dual adhesion and protection functions. Silica nanoparticles with spiky nanotopography loaded with spinosad possess rough surfaces. When applied topically, this nanospinosad formulation exhibited enhanced adhesion to both cattle hair and pest surface. The dual adhesion property led to significantly higher pest mortality toward tick (Rhipicephalus microplus, an ectoparasite) than a nanospinosad formulation using nanoparticles with smooth surface and a benchmark commercial product. The adhesion performance was further quantitatively measured using rainfastness test. Moreover, solar radiation test revealed that the nanospinosad exhibited >10 times higher photostability over the commercial product. This work paves the way toward the development of high performance nanobiopesticides for sustainable agricultural applications

Le Traitement Chirurgical Des Poches De Retraction Tympaniques De L\'enfant

Objectifs : Préciser les principes du traitement chirurgical et les particularités des poches de rétraction tympaniques (PDR) chez l\'enfant. Matériel et méthodes : Nous rapportons une étude rétrospective à propos de 37 PDR (28 enfants) opérés entre 1995 et 2006. Tous les patients avaient bénéficié d\'un examen clinique et un bilan audiométrique. Le traitement consistait en un renforcement tympanique par un greffon cartilagineux éventuellement associé à une attico-mastoïdectomie. Les résultats anatomiques et fonctionnels post opératoires ont été évalués avec un recul moyen de 29 mois. Résultats : L\'âge moyen des patients était de 10,5 ans et le sex-ratio de 1,33. Sept enfants avaient des antécédents d\'otite séromuqueuse bilatérale, avec pose d\'ATT. L\'hypoacousie était le signe fonctionnel le plus fréquent (67,8%). Les PDR étaient classées stade III, II et I (Charachon) respectivement dans 56,8%, 29,7% et 13,5% des cas. L\'audiométrie trouvait une surdité de transmission moyenne à 25 ± 15 dB. Une chirurgie de renforcement a été pratiquée dans tous les cas, associée à une mastoïdectomie chez 12 patients. Aucune récidive de rétraction n\'a été notée en post opératoire. Par ailleurs, l\'analyse des résultats fonctionnels a montré un gain auditif moyen de 10 dB et un Rinne résiduel < 15 dB dans 75,6% des cas. Conclusion : La chirurgie de renforcement tympanique par du cartilage, prend une place importante dans la prise en charge des PDR de l\'enfant et donne d\'excellents résultats anatomiques et fonctionnels.Objective: To precise the bases of surgical treatment and the particularities of tympanic retraction pockets (RP) in children. Materials and methods: We report a retrospective study about 37 RP (28 children) operated between 1995 and 2006. All patients had otological examination, nasal endoscopy and audiometric explorations. Treatment consists in reinforcement of the tympanic membrane with cartilage graft in all cases. After treatment, anatomical and functional results were evaluated with a mean follow-up of 29 months. Results: Mean-age was 10,5 years and sex-ratio 1,33. Seven children had bilateral seromucous otitis with ventilation tube insertion. Hearing-loss was the most frequent sign (67,8%). RP were classified (Charachon) stage III, II and I in 56,8%, 29,7% et 13,5%, respectively. Audiometery showed an average air conduction threshold of 25± 10 dB. Reinforcement tympanoplasty was performed in all cases, associated with canal wall-up mastoidectomy in 12 ears. No recurrence of retraction of the graft has been noted after treatment. Furthermore, analysis of functional results showed an average air conduction gain of 10 dB and air conduction gap < 15 dB in 75,6 % of cases. Conclusion: Reinforcement tympanoplasty with cartilage, takes a large place in the management of RP in children and achieves good anatomical and functional results. Keywords: Tympanic retraction – Surgery – Cartilage – Supervision Journal Tunisien d\'ORL et de chirurgie cervico-faciale Vol. 18 2007: pp. 12-1

Psychosocial adversity and socioeconomic position during childhood and epigenetic age: analysis of two prospective cohort studies

Psychosocial adversity in childhood (e.g. abuse) and low socioeconomic position (SEP) can have significant lasting effects on social and health outcomes. DNA methylation-based biomarkers are highly correlated with chronological age; departures of methylation-predicted age from chronological age can be used to define a measure of age acceleration, which may represent a potential biological mechanism linking environmental exposures to later health outcomes. Using data from two cohorts of women Avon Longitudinal Study of Parents and Children, (ALSPAC), N = 989 and MRC National Survey of Health and Development, NSHD, N = 773), we assessed associations of SEP, psychosocial adversity in childhood (parental physical or mental illness or death, parental separation, parental absence, sub-optimal maternal bonding, sexual, emotional and physical abuse and neglect) and a cumulative score of these psychosocial adversity measures, with DNA methylation age acceleration in adulthood (measured in peripheral blood at mean chronological ages 29 and 47 in ALSPAC and buccal cells at age 53 in NSHD). Sexual abuse was strongly associated with age acceleration in ALSPAC (sexual abuse data were not available in NSHD), e.g. at the 47-year time point sexual abuse associated with a 3.41 years higher DNA methylation age (95% CI 1.53 to 5.29) after adjusting for childhood and adulthood SEP. No associations were observed between low SEP, any other psychosocial adversity measure or the cumulative psychosocial adversity score and age acceleration. DNA methylation age acceleration is associated with sexual abuse, suggesting a potential mechanism linking sexual abuse with adverse outcomes. Replication studies with larger sample sizes are warranted

High field level crossing studies on spin dimers in the low dimensional quantum spin system Na2_2T2_2(C2_2O4_4)3_3(H2_2O)2_2 with T=Ni,Co,Fe,Mn

In this paper we demonstrate the application of high magnetic fields to study the magnetic properties of low dimensional spin systems. We present a case study on the series of 2-leg spin-ladder compounds Na$_2$T$_2$(C$_2$O$_4$)$_3$(H$_2$O)$_2$ with T = Ni, Co, Fe and Mn. In all compounds the transition metal is in the $T^{2+}$ high spin configuation. The localized spin varies from S=1 to 3/2, 2 and 5/2 within this series. The magnetic properties were examined experimentally by magnetic susceptibility, pulsed high field magnetization and specific heat measurements. The data are analysed using a spin hamiltonian description. Although the transition metal ions form structurally a 2-leg ladder, an isolated dimer model consistently describes the observations very well. This behaviour can be understood in terms of the different coordination and superexchange angles of the oxalate ligands along the rungs and legs of the 2-leg spin ladder. All compounds exhibit magnetic field driven ground state changes which at very low temperatures lead to a multistep behaviour in the magnetization curves. In the Co and Fe compounds a strong axial anisotropy induced by the orbital magnetism leads to a nearly degenerate ground state and a strongly reduced critical field. We find a monotonous decrease of the intradimer magnetic exchange if the spin quantum number is increased