Desarrollo de un medio de cultivo para potenciar la producción de componentes bioactivos en la microalga autóctona Scenedesmus obliquus

Se estudió el efecto de fuentes de nitrógeno (nitrato de sodio y urea) y de carbono (acetato de sodio y glucosa), así como el estrés salino (cloruro de sodio) sobre cultivo de la microalga Scenedesmus obliquus que potencien la producción de carotenoides totales, proteínas totales y fenoles totales. Se empleó como medio de cultivo base Allen & Arnon y la microalga Scenedesmus obliquus autóctona del Embalse de Salto Grande. Las condiciones experimentales que favorecieron la obtención de biomasa de microalga Scenedesmus obliquus rica en componentes bioactivos fueron: para carotenoides totales 0,24g urea/L; 3,68g glucosa/L y 54,71µmol/(m2s); proteínas totales 0,24g urea/L; 5,02g acetato de sodio/L y 54,71µmol/(m2s) y fenoles totales 31,00g urea/L; 3,68g glucosa/L y 45,04µmol/(m2 s). La concentración de carotenoides totales obtenida fue 473,85±11,00mg β-caroteno/g ms; de proteínas totales 7,09±0,23mg ASB/g ms y de fenoles totales, 16,78±0,84mg EAG/g ms. El estrés salino se desestimó ya que provocó una disminución de la concentración de los componentes de interés. De lo expuesto se concluye que el cultivo de Scenedesmus obliquus, bajo las condiciones de estrés señaladas, representa un proceso biotecnológico atractivo para la obtención de biomasa rica en componentes bioactivos con potencialidad para ser utilizada como aditivo natural en la formulación de alimentos ARK: http://id.caicyt.gov.ar/ark:/s22504559/t9bmfmnb

The mating competence of geographically diverse Leishmania major strains in their natural and unnatural sand fly vectors

Invertebrate stages of Leishmania are capable of genetic exchange during their extracellular growth and development in the sand fly vector. Here we explore two variables: the ability of diverse L. major strains from across its natural range to undergo mating in pairwise tests; and the timing of the appearance of hybrids and their developmental stage associations within both natural (Phlebotomus duboscqi) and unnatural (Lutzomyia longipalpis) sand fly vectors. Following co-infection of flies with parental lines bearing independent drug markers, doubly-drug resistant hybrid progeny were selected, from which 96 clonal lines were analyzed for DNA content and genotyped for parent alleles at 4-6 unlinked nuclear loci as well as the maxicircle DNA. As seen previously, the majority of hybrids showed '2n' DNA contents, but with a significant number of '3n' and one '4n' offspring. In the natural vector, 97% of the nuclear loci showed both parental alleles; however, 3% (4/150) showed only one parental allele. In the unnatural vector, the frequency of uniparental inheritance rose to 10% (27/275). We attribute this to loss of heterozygosity after mating, most likely arising from aneuploidy which is both common and temporally variable in Leishmania. As seen previously, only uniparental inheritance of maxicircle kDNA was observed. Hybrids were recovered at similar efficiencies in all pairwise crosses tested, suggesting that L. major lacks detectable 'mating types' that limit free genetic exchange. In the natural vector, comparisons of the timing of hybrid formation with the presence of developmental stages suggest nectomonads as the most likely sexually competent stage, with hybrids emerging well before the first appearance of metacyclic promastigotes. These studies provide an important perspective on the prevalence of genetic exchange in natural populations of L. major and a guide for experimental studies to understand the biology of mating

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Personalisation: A theoretical possibility to reinvigorate children’s interest in storybook reading and facilitate greater book diversity

Since the early 2010s, there has been a proliferation of new platforms for children’s stories (e.g. storybook apps or iBooks), but not necessarily greater diversity of story content or children’s greater interest in reading. This article argues for a new approach to address the apparent paradox of a wider availability of children’s literature combined with children’s eroded reading interest. The issue is suggested to be addressed by considering the agency and aesthetic dimensions which lie at the heart of personalisation theory. Translating agency into reading practice means establishing children’s early authoring, which can result in an eclectic approach to content and increased reading motivation, as long as children’s aesthetic choices are fully supported. However, it is also argued that early authoring should not be conflated with achieving an overly child-centred literature, which would ignore the reciprocity dimension of community and society relations. Digital book-making is suggested to offer original concepts which might provide an alternative approach for future work in the area of early authoring

Infection levels at time of dissection in <i>P. duboscqi</i> midguts with and without hybrids.

<p>Midguts were dissected on the indicated times post-feeding and scored for the number of viable promastigotes. Bars represent the median numbers of promastigotes per midgut.</p

Summary of Fn/Sat×Lv39c5/Hyg crosses in <i>Lu. Longipalpis</i>.

<p>Summary of Fn/Sat×Lv39c5/Hyg crosses in <i>Lu. Longipalpis</i>.</p

Summary of <i>L. major</i> crosses in <i>P. duboscqi</i>.

<p>Summary of <i>L. major</i> crosses in <i>P. duboscqi</i>.</p

Summary of Fn/Sat×LV39c5/Hyg hybrid genotypes generated in <i>P. duboscqi</i>.

<p>H, hybrid; ND, not determined.</p

Summary of Fn/Sat×Sd/Hyg hybrid genotypes generated in <i>P. duboscqi</i>.

<p>H, hybrid; ND, not determined.</p