Chitin in a dual role as substrate for Streptomyces griseus and as adsorbent for streptomycin produced during fermentation

Streptomycin production from chitin by Streptomyces griseus was compared using two different types of bioreactor. The first was equipped with a combined U-shaped paddle and Rushton impeller. Also employed was a bioreactor of novel design in which the chitin was contained in a wire mesh basket that was totally submerged in a liquid salts medium. During operation the chitin was gently fluidised by air admitted into the basket. Fermentation was continued in both bioreactors until maximum antibiotic titres were achieved whereupon operation was interrupted to allow the streptomycin adsorbed to the chitin substrate to be extracted into pH 3.0 buffer before continuing fermentation of the same batch of chitin a second time. At a chitin concentration of 10 % (w/v) the highest streptomycin yields (c. 5.5 mg/L) were obtained using the stirred bioreactor, however growth occurred more rapidly in the vertical basket bioreactor

Direct FTIR assay of streptomycin in agar

Streptomycin titres in samples of agar media on which various species of streptomycetes were cultured were obtained by Fourier Transform Infra Red (FTIR) spectroscopy. Titres were directly comparable to those obtained by bioassay based on Bacillus subtilis inhibition. Analysis by this method could be used to facilitate the isolation of high level antibiotic-producing mutants

Production of streptomycin from chitin using Streptomyces griseus in bioreactors of different configuration

Streptomyces griseus was cultured in three different bioreactors in a medium containing chitin flakes. When a conventional bioreactor stirred by two sets of Rushton impellers and operated at high speed was used, the yield of streptomycin (3.1 mg/l) was the highest observed and occurred at approximately 500 hours. Cultivation of S. griseus in a bioreactor stirred at low speed by a U-shaped paddle resulted in a lower yield of streptomycin (1.8 mg/l) but this was achieved in a shorter period of time (400 hours). Increasing the concentration of chitin from 5 to 10 % w/v had no significant effect on either of these two parameters. The use of a novel vertical basket bioreactor in which the chitin flakes were contained within a wire mesh basket and were gently fluidised by air, enabled comparatively high yields of streptomycin (2.8 mg/l) in the relatively short time of 300 hours

Shrinking into the big city: influence of genetic and environmental factors on urban dragon lizard morphology and performance capacity

Urban wildlife faces a novel set of challenges resulting in selective pressure that can lead to population-level changes. We studied Australian water dragons (Intellagama lesueurii) from urban and natural populations to test if urban populations differed in body size, shape, and performance capacity. If urban-derived morphology has arisen through selection, we predicted distinct morphological differences between wild dragons from urban and natural areas in both adult and hatchling life-stages. Urban hatchlings were morphologically distinct (shorter body lengths and longer limbs) from natural populations, while urban adult males continued this trend but only for body size (shorter body lengths). We then experimentally reared hatchlings originating from urban and natural populations within urban- and natural-style enclosures (2 x 2 factorial design) for a year to determine if differences in morphology and performance capacity (sprint speed, endurance, and clinging ability) were related to either the individual's origin population or developmental environment. Yearlings reared in urban-style enclosures, irrespective of population origin, had smaller body sizes compared to those from natural-style enclosures, suggesting developmental environment was affecting their morphology. Despite this difference in body size, yearling dragon performance capacity was not significantly different between treatments. Overall, this study provides evidence of a complex relationship driving urban-divergent morphology - whereby urban dragons emerge as smaller hatchlings with longer limbs (innate traits) and are then further influenced by the urban environments that they develop in (phenotypic plasticity); however, and potentially owing to behavioral, ecological, and demographical differences, these changes appear to be sex-specific

Using learning design as a framework for supporting the design and reuse of OER

The paper will argue that adopting a learning design methodology may provide a vehicle for enabling better design and reuse of Open Educational Resources (OERs). It will describe a learning design methodology, which is being developed and implemented at the Open University in the UK. The aim is to develop a 'pick and mix' learning design toolbox of different resources and tools to help designers/teachers make informed decisions about creating new or adapting existing learning activities. The methodology is applicable for designers/teachers designing in a traditional context – such as creation of materials as part of a formal curriculum, but also has value for those wanting to create OERs or adapt and repurpose existing OERs. With the increasing range of OERs now available through initiatives as part of the Open Courseware movement, we believe that methodologies, such as the one we describe in this paper, which can help guide reuse and adaptation will become increasingly important and arguably are an important aspect of ensuring longer term sustainability and uptake of OERs. Our approach adopts an empirically based approach to understanding and representing the design process. This includes a range of evaluation studies (capturing of case studies, interviews with designers/teachers, in-depth course evaluation and focus groups/workshops), which are helping to develop our understanding of how designers/teachers go about creating new learning activities. Alongside this we are collating an extensive set of tools and resources to support the design process, as well as developing a new Learning Design tool that helps teachers articulate and represent their design ideas. The paper will describe how we have adapted a mind mapping and argumentation tool, Compendium, for this purpose and how it is being used to help designers and teachers create and share learning activities. It will consider how initial evaluation of the use of the tool for learning design has been positive; users report that the tool is easy to use and helps them organise and articulate their learning designs. Importantly the tool also enables them to share and discuss their thinking about the design process. However it is also clear that visualising the design process is only one aspect of design, which is complex and multi-faceted

Leopard tortoise (Stigmochelys pardalis) road mortality and extralimital occurrence in Western Cape, South Africa

During field surveys in the Spring of 2018 we made two observations of Leopard Tortoises (Stigmochelys pardalis) on roadsides near Lambert's Bay, WC, South Africa. One was a deceased adult female, killed as a result of a tortoise-vehicle collision. The other was a live adult females, which was move off the road in the direction she was headed. These observations illustrate that even the largest tortoise species in the region can be suseptable to road mortlaity, a known threat of turtle and torioses populations globally. Furthermore, these observations occured well outside the species presumed native range and listed introduced range

Trajectory versus probability density entropy

We study the problem of entropy increase of the Bernoulli-shift map without recourse to the concept of trajectory and we discuss whether, and under which conditions if it does, the distribution density entropy coincides with the Kolmogorov-Sinai entropy, namely, with the trajectory entropy.Comment: 24 page

Application of regulatory sequence analysis and metabolic network analysis to the interpretation of gene expression data

We present two complementary approaches for the interpretation of clusters of co-regulated genes, such as those obtained from DNA chips and related methods. Starting from a cluster of genes with similar expression profiles, two basic questions can be asked: 1. Which mechanism is responsible for the coordinated transcriptional response of the genes? This question is approached by extracting motifs that are shared between the upstream sequences of these genes. The motifs extracted are putative cis-acting regulatory elements. 2. What is the physiological meaning for the cell to express together these genes? One way to answer the question is to search for potential metabolic pathways that could be catalyzed by the products of the genes. This can be done by selecting the genes from the cluster that code for enzymes, and trying to assemble the catalyzed reactions to form metabolic pathways. We present tools to answer these two questions, and we illustrate their use with selected examples in the yeast Saccharomyces cerevisiae. The tools are available on the web (http://ucmb.ulb.ac.be/bioinformatics/rsa-tools/; http://www.ebi.ac.uk/research/pfbp/; http://www.soi.city.ac.uk/~msch/)

Simulation numérique du couplage surface/canopée lors de la propagation d'un feu de cime en forêt boréale

Cette étude concerne la modélisation numérique de l'ignition et de la propagation d'un feu de cime dans une forêt de type boréale. La formulation mathématique est basée sur une approche multi-phasique, construite à partir des équations de conservation (masse, quantité de mouvement, énergie) gouvernant l'évolution du système couplé formé par la végétation et l'atmosphère ambiant. Le modèle a préalablement été testé à petite échelle, sur des feux de litière homogène et à plus grande échelle, sur des feux de prairie et en garrigue Méditerranéenne. Les résultats ont été comparés avec des données expérimentales de la littérature, et les prédictions des modèles empiriques opérationnels développés en Australie (MkV) et aux Etats Unis (BEHAVE). Le modèle a été étendu à un profil de végétation composé d'une couche arbustive et d'une canopée. Les résultats mettent en évidence le rôle joué par le combustible de surface sur la dynamique générale du feu de cime. Les résultats numériques ont été confrontés aux données collectées à l'occasion de campagnes expérimentales internationales réalisées au Canada