Protoplasting, regeneration and fusion of lactobacilli

Cells of two Lactobacillus strains were protoplasted by treatment with mutanolysin or combinations of mutanolysin and lysozyme for various incubation times. Almost all protoplastization treatments tested were suitable for reducing the number of osmotically stable cells two log cycles. Protoplasts were successfully regenerated on a complex medium containing McCl2, CaCl2, gelatin, raffinose and bovine serum albumin (BSA). Maximal regeneration frequencies ranged from 6 to 10 % for L. casei subsp. rhamnosus and L. lactis, respectively. The use of agar overlays did not affect the regeneration ability of either strain. Treatment of protoplasts of both strains with 40 % polyethylene glycol (PEG) resulted in a regeneration frequency decrease of several hundredfold. Using the different resistance levels of both strains to the antibiotics kanamycin and penicillin as selected genetic markers, attempts to fuse protoplasts of these lactobacilli in the presence of 40 % PEG were not successful

Building Babies - Chapter 16

In contrast to birds, male mammals rarely help to raise the offspring. Of all mammals, only among rodents, carnivores, and primates, males are sometimes intensively engaged in providing infant care (Kleiman and Malcolm 1981). Male caretaking of infants has long been recognized in nonhuman primates (Itani 1959). Given that infant care behavior can have a positive effect on the infant’s development, growth, well-being, or survival, why are male mammals not more frequently involved in “building babies”? We begin the chapter defining a few relevant terms and introducing the theory and hypotheses that have historically addressed the evolution of paternal care. We then review empirical findings on male care among primate taxa, before focusing, in the final section, on our own work on paternal care in South American owl monkeys (Aotus spp.). We conclude the chapter with some suggestions for future studies.Deutsche Forschungsgemeinschaft (HU 1746/2-1) Wenner-Gren Foundation, the L.S.B. Leakey Foundation, the National Geographic Society, the National Science Foundation (BCS-0621020), the University of Pennsylvania Research Foundation, the Zoological Society of San Dieg

Biogenic guanine crystals are solid solutions of guanine and other purine metabolites

Highly reflective crystals of the nucleotide base guanine are widely distributed in animal coloration and visual systems. Organisms precisely control the morphology and organization of the crystals to optimize different optical effects, but little is known about how this is achieved. Here we examine a fundamental question that has remained unanswered after over 100 years of research on guanine: what are the crystals made of? Using solution-state and solid-state chemical techniques coupled with structural analysis by powder XRD and solid-state NMR, we compare the purine compositions and the structures of seven biogenic guanine crystals with different crystal morphologies, testing the hypothesis that intracrystalline dopants influence the crystal shape. We find that biogenic “guanine” crystals are not pure crystals but molecular alloys (aka solid solutions and mixed crystals) of guanine, hypoxanthine, and sometimes xanthine. Guanine host crystals occlude homogeneous mixtures of other purines, sometimes in remarkably large amounts (up to 20% of hypoxanthine), without significantly altering the crystal structure of the guanine host. We find no correlation between the biogenic crystal morphology and dopant content and conclude that dopants do not dictate the crystal morphology of the guanine host. The ability of guanine crystals to host other molecules enables animals to build physiologically “cheaper” crystals from mixtures of metabolically available purines, without impeding optical functionality. The exceptional levels of doping in biogenic guanine offer inspiration for the design of mixed molecular crystals that incorporate multiple functionalities in a single material

Rearing without paternal help in the Bolivian owl monkey Aotus azarae boliviensis: a case study

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich. - This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively. - Primärausgabe im Karger-Verlag (www.karger.com/?doi=10.1159/000021572) erschienen

Rearing without Paternal Help in the Bolivian Owl Monkey <i>Aotus azarae boliviensis:</i> A Case Study¹

Objeto de aprendizaje: Presentación multimediaThis resource deals with how to address changes in software requirements, including prototyping and incremental deliveries.Este recurso trata sobre cómo abordar los cambios en los requerimientos del software, incluyendo el prototipado y las entregas incrementales.1. Introducción1.1. Hacer frente a los cambios1.1.1. Reducir los costos1.1.2. Prototipado del software1.1.3. Beneficios del prototipado1.1.4. Proceso de desarrollo de un prototipo1.1.5. Descartar prototipos1.2. Entregas incrementales1.2.1. Diferencias entre desarrollo y entrega incremental1.2.2. Gráfica1.2.3. Ventajas del desarrollo incremental1.2.4. Problemas del desarrollo incremental1.0Ingeniero(a) de SistemasPregrad

Electrostatic interplay: The interaction triangle of polyamines, silicic acid, and phosphate studied through turbidity measurements, silicomolybdic acid test, and 29Si NMR spectroscopy

The discovery of long-chain polyamines as biomolecules that are tightly associated to biosilica in diatom cell walls has inspired numerous in vitro studies aiming to characterize polyamine–silica interactions. The determination of these interactions at the molecular level is of fundamental interest on one hand for the understanding of cell wall biogenesis in diatoms and on the other hand for designing bioinspired materials synthesis approaches. The present contribution deals with the influence of amines and polyamines upon the initial self-assembly processes taking place during polyamine-mediated silica formation in solution. The influence of phosphate upon these processes is studied. For this purpose, sodium metasilicate solutions containing additives such as polyallylamine, allylamine and others in the presence/absence of phosphate were investigated. The analyses are based mainly on turbidity measurements yielding information about the early aggregation steps which finally give rise to the formation and precipitation of silica

Mineralogical Imaging for Characterization of the Per Geijer Apatite Iron Ores in the Kiruna District, Northern Sweden: A Comparative Study of Mineral Liberation Analysis and Raman Imaging

The Per Geijer iron oxide apatite deposits are important potential future resources for Luossavaara-Kiirunavaara Aktiebolag (LKAB) which has been continuously mining magnetite/hematite ores in northern Sweden for over 125 years. Reliable and quantitative characterization of the mineralization is required as these ores inherit complex mineralogical and textural features. Scanning electron microscopy-based analyses software, such as mineral liberation analyzer (MLA) provide significant, time-efficient analyses. Similar elemental compositions of Fe-oxides and, therefore, almost identical backscattered electron (BSE) intensities complicate their discrimination. In this study, MLA and Raman imaging are compared to acquire mineralogical data for better characterization of magnetite and hematite-bearing ores. The different approaches demonstrate advantages and disadvantages in classification, imaging, discrimination of iron oxides, and time consumption of measurement and processing. The obtained precise mineralogical information improves the characterization of ore types and will benefit future processing strategies for this complex mineralization

Acidified water glass in the selective flotation of scheelite from calcite, part II: species in solution and related mechanism of the depressant

Sodium silicate is one of the main depressants against calcite and fluorite in the scheelite flotation industry. In the first part of this article, the authors acidified sodium silicate (AWG) with three acids (sulfuric, oxalic and hydrochloric) to improve its performance. Results showed that acidified water glass outperforms alkaline water glass in terms of selectivity: it increases mainly the grade by further depressing silicates and calcium-bearing minerals. In most cases, AWG requires lower dosages to do so. The effect of acidified water glass is evaluated through Mineral Liberation Analysis (MLA), froth analysis, Raman and Nuclear Magnetic Resonance (NMR) spectroscopy in order to hypothesize its mechanism. MLA shows that AWG affects silicates and sulfides more intensely than semi-soluble salttype minerals. Froth observations indicate other species in solution associated to the acid having an impact on the flotation results. Raman spectroscopy and NMR measurements indicate that the solution undergoes deep depolymerization when water glass is acidified. Lower molecular weight silica species, specifically Si-O monomers such as SiO(OH)3- will be responsible for the depression of the gangue minerals and are the drivers of the selectivity of AWG, more than orthosilicic acid. Depolymerization is more or less effective depending on the mass ratio of the acid to water glass and depending on the acid

Directed assembly of nanoparticles to isolated diatom valves using the non-wetting characteristics after pyrolysis

A novel strategy for a directed nanoparticle coupling to isolated Stephanopyxis turris valves is presented. After pyrolysis, the valves exhibit incomplete wetting due to their characteristic T-shaped profiles as a prerequisite for a regioselective coupling reaction. A micromanipulation system allows for precise handling and their immobilization onto an adhesive substrate and manipulation into arrays