Selective detection of bacterial layers with terahertz plasmonic antennas

Current detection and identification of micro-organisms is based on either rather unspecific rapid microscopy or on more accurate complex, time-consuming procedures. In a medical context, the determination of the bacteria Gram type is of significant interest. The diagnostic of microbial infection often requires the identification of the microbiological agent responsible for the infection, or at least the identification of its family (Gram type), in a matter of minutes. In this work, we propose to use terahertz frequency range antennas for the enhanced selective detection of bacteria types. Several microorganisms are investigated by terahertz time-domain spectroscopy: a fast, contactless and damage-free investigation method to gain information on the presence and the nature of the microorganisms. We demonstrate that plasmonic antennas enhance the detection sensitivity for bacterial layers and allow the selective recognition of the Gram type of the bacteria

Possible import routes of proteins into the cyanobacterial endosymbionts/plastids of Paulinella chromatophora

The rhizarian amoeba Paulinella chromatophora harbors two photosynthetically active and deeply integrated cyanobacterial endosymbionts acquired ~60 million years ago. Recent genomic analyses of P. chromatophora have revealed the loss of many essential genes from the endosymbiont’s genome, and have identified more than 30 genes that have been transferred to the host cell’s nucleus through endosymbiotic gene transfer (EGT). This indicates that, similar to classical primary plastids, Paulinella endosymbionts have evolved a transport system to import their nuclear-encoded proteins. To deduce how these proteins are transported, we searched for potential targeting signals in genes for 10 EGT-derived proteins. Our analyses indicate that five proteins carry potential signal peptides, implying they are targeted via the host endomembrane system. One sequence encodes a mitochondrial-like transit peptide, which suggests an import pathway involving a channel protein residing in the outer membrane of the endosymbiont. No N-terminal targeting signals were identified in the four other genes, but their encoded proteins could utilize non-classical targeting signals contained internally or in C-terminal regions. Several amino acids more often found in the Paulinella EGT-derived proteins than in their ancestral set (proteins still encoded in the endosymbiont genome) could constitute such signals. Characteristic features of the EGT-derived proteins are low molecular weight and nearly neutral charge, which both could be adaptations to enhance passage through the peptidoglycan wall present in the intermembrane space of the endosymbiont’s envelope. Our results suggest that Paulinella endosymbionts/plastids have evolved several different import routes, as has been shown in classical primary plastids

Quality of life in families with a transition aged young adult on the autism spectrum

(Sc. D.) -- Towson University, 2012.The purpose of this study was to describe family quality of life (FQOL) from the perspective of families with youth on the autism spectrum at or nearing the age of transition from school to adulthood. A qualitative phenomenology approach was used. Participants included ten families made up of six mothers, two fathers, and two grandmothers. The primary form of data collection was two in- depth interviews. Observations and field notes supplemented interview data, and previously administered Maryland Autism Services Surveys (MASS) were examined to contribute to the triangulation of the data. Trustworthiness of the data was enhanced by the presence of a second researcher during data collection and analysis, peer debriefing, and member checking. Another purpose of this study was to explore sensory processing in these transition aged youth, and to investigate the influence of sensory processing difficulties on family life. This was explored through the interviews, and through administration of the Adolescent/ Adult Sensory Profile, which was filled out by the family members. Results of the qualitative study revealed three themes that describe FQOL from the participants' perspectives: changes associated with puberty and associated disorders that manifest or worsen during puberty affect autism and challenge quality of life; occupations are influenced and restricted when there is a family member on the autism spectrum; and the onus of responsibility for transition falls on the family. The investigation into sensory processing in young adults revealed the existence of difficulties in sensory processing, with trends noted in the types of difficulties seen in these young adults. Sensory processing influenced FQOL, with families modifying activities to accommodate their young adult's sensory needs. Implications of these results for the study of occupation and for the practice of occupational therapy are discussed

Sexuality and Spinal Cord Injury: The Lived Experiences of Intimate Partners

Although sexuality is an integral aspect of the human experience, individuals who sustain a spinal cord injury (SCI) often receive inadequate education to facilitate successful participation in sexual activities. Intimate partners are often not included in discussions related to sexuality during the rehabilitative process. The purpose of this study was to identify the lived experiences of intimate partners of individuals with SCI related to sexuality. Four intimate partners were selected to participate in semistructured interviews related to their lived experiences of sexuality. Participants identified aspects of SCI, extreme discomfort due to self-perceived sexual norms, and a lack of education as contributors to unsuccessful participation in sexual activity. Coupled sexual activity is a complex phenomenon which includes factors that influence both the injured individuals as well as their intimate partners. To provide effective interventions in addressing sexuality, practitioners should consider the entire issue, the couple. </jats:p

New version of the negative stain

We have developed a new version of the negative stain which is very quick, reliable, and easy to perform and which uses a waterproof marking pen instead of nigrosin. It is ideal for teaching the negative staining technique to beginning student microbiologists.</jats:p

Remote Teaching and Assessment of Professional Science Laboratory Skills

An approach and system for remote teaching and assessment of a range of science laboratory skills including use of pipettes, micropipettes, dispensing solids by mass and aseptic manipulations is described. This approach assures that students have a range of job-ready practical skills before undertaking a training placement in a commercial laboratory. The system allows two-way audio and video between the student and the educator, allows the educator to remotely know the reading on a digital laboratory balance and allows student and educator to view each other’s inputs in real time on a mock Laboratory Information Management System (simulating those used in professional laboratories).</jats:p

The permeability of the wall fabric of Escherichia coli and Bacillus subtilis.

To study the overall structure of the peptidoglycan fabric of the sacculi of gram-negative and gram-positive walls, actively growing cultures of Escherichia coli and Bacillus subtilis were treated with boiling sodium dodecyl sulfate solutions. The sacculi were then treated with enzymes to eliminate proteins and nucleic acids. These intact saccoli were probed with fluorescein-labeled dextrans with a range of known molecular weights. The penetration of the probes could be monitored by the negative-staining appearance in the fluorescence microscope. At several chosen times, the molecular weight fraction that allowed barely observable entry of the fluorescein-labeled probe and the molecular weight fraction that penetrated to achieve almost, but not quite, the concentration of probe in the solution external to the sacculi were determined. From three pairs of times and molecular weights that met one or the other of these two criteria, the effective pore size could be calculated. The minimum size of protein molecule that could diffuse through the pores was also calculated. Two mathematical models, which gave essentially the same results, were used to interpret the experimental data: one for the permeation of random coils through a surface containing holes and the other for rigid spheres diffusing through water-filled cylindrical pores. The mean estimate of the effective hole radius in walls from E. coli is 2.06 nm, and that of the effective hole size in walls from B. subtilis is 2.12 nm. These results are supported by experiments in which the loss of preloaded cells was monitored. Various fluorescein-labeled dextran samples were mixed with samples of intact cell walls, held for a long time, and then diluted. The efflux of the dextrans was monitored. Neither large nor small dextrans stained under these conditions. Only with dextran samples of a sufficiently small size were the sacculi filled during the preincubation period, and only with the largest of these could the probe not escape quickly. From the pore (or mesh) size, it can be concluded that the wall fabric of both organisms has few imperfections and that the major passageway is through the smallest possible pore, or "tessera," formed by the maximal cross-linking of the peptides from glycan chain to glycan chain compatible with the degree of rotational flexibility of the chains of repeating disaccharides of N-acetyl muramic acid and N-acetyl glucosamine. A tessera is composed of two chains of eight saccharides cross-linked by two octapeptides. The size of a globular hydrophilic molecule, if it did not bind to wall components, that could pass freely through the meshwork of an unstretched sacculus of either organism is roughly 25 kDa. We stress that this is only a rough estimate, and it may be possible for proteins of less than 50 kDa to pass through the native wall during normal growth conditions