Trace-gas metabolic versatility of the facultative methanotroph Methylocella silvestris

The climate-active gas methane is generated both by biological processes and by thermogenic decomposition of fossil organic material, which forms methane and short-chain alkanes, principally ethane, propane and butane1, 2. In addition to natural sources, environments are exposed to anthropogenic inputs of all these gases from oil and gas extraction and distribution. The gases provide carbon and/or energy for a diverse range of microorganisms that can metabolize them in both anoxic3 and oxic zones. Aerobic methanotrophs, which can assimilate methane, have been considered to be entirely distinct from utilizers of short-chain alkanes, and studies of environments exposed to mixtures of methane and multi-carbon alkanes have assumed that disparate groups of microorganisms are responsible for the metabolism of these gases. Here we describe the mechanism by which a single bacterial strain, Methylocella silvestris, can use methane or propane as a carbon and energy source, documenting a methanotroph that can utilize a short-chain alkane as an alternative to methane. Furthermore, during growth on a mixture of these gases, efficient consumption of both gases occurred at the same time. Two soluble di-iron centre monooxygenase (SDIMO) gene clusters were identified and were found to be differentially expressed during bacterial growth on these gases, although both were required for efficient propane utilization. This report of a methanotroph expressing an additional SDIMO that seems to be uniquely involved in short-chain alkane metabolism suggests that such metabolic flexibility may be important in many environments where methane and short-chain alkanes co-occur

Clinical practice: Breastfeeding and the prevention of allergy

The increase in allergic disease prevalence has led to heightened interest in the factors determining allergy risk, fuelled by the hope that by influencing these factors one could reduce the prevalence of allergic conditions. The most important modifiable risk factors for allergy are maternal smoking behaviour and the type of feeding. A smoke-free environment for the child (to be), exclusive breastfeeding for 4–6 months and the postponement of supplementary feeding (solids) until 4 months of age are the main measures considered effective. There is no place for restricted diets during pregnancy or lactation. Although meta-analyses suggest that hypoallergenic formula after weaning from breastfeeding grants protection against the development of allergic disease, the evidence is limited and weak. Moreover, all current feeding measures aiming at allergy prevention fail to show effects on allergic manifestations later in life, such as asthma. In conclusion, the allergy preventive effect of dietary interventions in infancy is limited. Counselling of future parents on allergy prevention should pay attention to these limitations

Comparison of the pathogenesis of the highly passaged MCMV Smith strain with that of the low passaged MCMV HaNa1 isolate in BALB/c mice upon oronasal inoculation

Murine cytomegalovirus (MCMV) Smith strain is widely used in mouse models to study HCMV infections. Due to high serial passages, MCMV Smith has acquired genetic and biological changes. Therefore, a low passaged strain would be more relevant to develop mouse models. Here, the pathogenesis of an infection with MCMV Smith was compared with that of an infection with a low passaged Belgian MCMV isolate HaNa1 in BALB/c adult mice following oronasal inoculation with either a low (10(4) TCID50/mouse) or high (10(6) TCID50/mouse) inoculation dose. Both strains were mainly replicating in nasal mucosa and submandibular glands for one to two months. In nasal mucosa, MCMV was detected earlier and longer (1-49 days post inoculation (dpi)) and reached higher titers with the high inoculation dose compared to the low inoculation dose (14-35 dpi). In submandibular glands, a similar finding was observed (high dose: 7-49 dpi; low dose: 14-42 dpi). In lungs, both strains showed a restricted replication. In spleen, liver and kidneys, only the Smith strain established a productive infection. The infected cells were identified as olfactory neurons and sustentacular cells in olfactory epithelium, macrophages and dendritic cells in NALT, acinar cells in submandibular glands, and macrophages and epithelial cells in lungs for both strains. Antibody analysis demonstrated for both strains that IgG(2a) was the main detectable antibody subclass. Overall, our results show that significant phenotypic differences exist between the two strains. MCMV HaNa1 has been shown to be interesting for use in mouse models in order to get better insights for HCMV infections in immunocompetent humans

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Περιέχει την περίληψηΜέσα στα πλαίσια της Κοινωνίας της Πληροφορίας οι βιβλιοθηκονόμοι διεκδικούν, άλλοτε πετυχημένα, άλλοτε όχι και τόσο, ένα πιο ενεργό και απαιτητικό ρόλο, προβάλλοντας το επιχείρημα πώς όσο μεγαλύτερη είναι η παραγωγή πληροφορίας και γνώσης και η παροχή πληροφόρησης τόσο mo απαιτητική είναι και η διαδικασία που αναγκάζεται να ακολουθήσει ο χρήστης ώστε να ικανοποιήσει τις ανάγκες του. Αλλά, η αναγκαιότητα του βιβλιοθηκονόμου (ως επιστήμονα της πληροφόρησης πλέον), του διαμεσολαβητή, δηλαδή, ανάμεσα στην πληροφορία και στον χρήστη, δικαιολογεί απαραιτήτως και την αναγκαιότητα για την ίδια τη Βιβλιοθήκη; Τεκμηριώνεται, δηλαδή, η ύπαρξη αυτού του οργανισμού ως μη κερδοσκοπικού, πολιτιστικού ιδρύματος που εξυπηρετεί όχι μόνο πληροφοριακές αλλά και ψυχαγωγικές, εκπαιδευτικές, κοινωνικοοικονομικές ανάγκες των επισκεπτών του; Και τότε, το έργο του βιβλιοθηκονόμου πώς προδιαγράφεται; Ποιο το περιεχόμενο και ο τρόπος της διαμεσολάβησης; Πρόκειται για σύνθεση ή μηχανιστική διάδοση της πληροφορίας; Αν η Πληροφορία διακινείται, στις μέρες μας κυρίως και πρωτίστως, με ηλεκτρονικά μέσα, τότε το αυτονόητο της ύπαρξης ενός απτού οικοδομήματος που στεγάζει την πληροφορία παύει να ισχύει και είτε πρέπει να καταλυθεί, είτε να εφευρεθεί από την αρχή, προσδίδοντας νέα επίκαιρα χαρακτηριστικά σε ένα αρχαιότατο κατασκεύασμα