University College Cork

About: University College Cork is a education organization based out in Cork, Ireland. It is known for research contribution in the topics: Population & Context (language use). The organization has 12056 authors who have published 28452 publications receiving 958414 citations. The organization is also known as: Coláiste na hOllscoile Corcaigh & National University of Ireland, Cork.

A DNA diagnostic biosensor: development, characterisation and performance

Abstract: The aim of this work is to develop a sensor for specific DNA sequences, using non-complex synthetic single-stranded oligonucleotides as a model system. A capacitance-based sensor for the direct detection of DNA sequences is described. Hybridisation of analyte DNA with immobilised DNA on the silicon surface induces charge effects, altering the dielectric properties of the biolayer, and can be detected by the associated change in the measured capacitance. DNA has been immobilised on a silicon electrode either by passive adsorption or covalent coupling via 4-aminobutyldimethylmethoxysilane (4-ABDMMS). The work presented here introduces a colourimetric immunodetection technique for the evaluation of the immobilisation process and describes the electrical characterisation and performance of three silicon-based sequence-specific DNA sensors. These sensors consisted of a standard electrolyte-insulator-semiconductor (EIS) structure with covalently bound probe DNA, a mechanically degraded structure with passively adsorbed probe DNA and a mechanically degraded structure with covalently bound probe DNA. The last device had an improved signal to noise ratio and was, therefore, used to construct a standard curve, revealing a detection Limit of 100 pmol DNA. On addition of analyte DNA, then was a decrease in measured capacitance. This response was fast, specific and required no addition of mediators to enhance or amplify the signal. This device can be optimised for the detection of complex sequences.

Biodiversity of the bacterial flora on the surface of a smear cheese.

Abstract: The bacteria on the surface of a farmhouse smear-ripened cheese at four stages of ripening (4, 16, 23, and 37 days) from inoculated (i.e., deliberately inoculated with Brevibacterium linens BL2) and noninoculated (not deliberately inoculated with B. linens BL2) cheese were investigated. The results show that, contrary to accepted belief, B. linens is not a significant member of the surface flora of smear cheese and no microbial succession of species occurred during the ripening of the cheeses. Of 400 isolates made, 390 were lactate-utilizing coryneforms and 10 were coagulase-negative Staphylococcus spp. A detailed analysis of the coryneforms was undertaken using phenotypic analysis, molecular fingerprinting, chemotaxonomic techniques, and 16S rRNA gene sequencing. DNA banding profiles (ramdom amplified polymorphic DNA [RAPD]-PCR) of all the coryneform isolates showed large numbers of clusters. However, pulsed-field gel electrophoresis (PFGE) of the isolates from the cheeses showed that all isolates within a cluster and in many contiguous clusters were the same. The inoculated and noninoculated cheeses were dominated by single clones of novel species of Corynebacterium casei (50.2% of isolates), Corynebacterium mooreparkense (26% of isolates), and Microbacterium gubbeenense (12.8% of isolates). In addition, five of the isolates from the inoculated cheese were Corynebacterium flavescens. Thirty-seven strains were not identified but many had similar PFGE patterns, indicating that they were the same species. C. mooreparkense and C. casei grew at pH values below 4.9 in the presence of 8% NaCl, while M. gubbeenense did not grow below pH 5.8 in the presence of 5 to 10% NaCl. B. linens BL2 was not recovered from the inoculated cheese because it was inhibited by all the Staphylococcus isolates and many of the coryneforms. It was concluded that within a particular batch of cheese there was significant bacterial diversity in the microflora on the surface.

Emerging applications of phosphorescent metalloporphyrins.

Abstract: The subject of phosphorescent metalloporphyrins is reviewed, focusing mainly on the development and application of Pt- and Pd-porphyrins. A summary of their general chemical and photophysical properties, and guidelines for rational design of the phosphorescent labels, bioconjugates and probes is given. Examples of different detection formats and particular bio-analytical applications developed in recent years are presented. The potential of phosphorescent porphyrin label methodology is discussed and compared to that of the long-decay fluorescent lanthanide chelates and other common fluorophores.

Arabidopsis thaliana plants acclimated to low dose rates of ultraviolet B radiation show specific changes in morphology and gene expression in the absence of stress symptoms

Abstract: Ultraviolet B (UV-B) acclimation comprises complex and poorly understood changes in plant metabolism. The effects of chronic and ecologically relevant UV-B dose rates on Arabidopsis thaliana were determined. The UV-B acclimation process was studied by measuring radiation effects on morphology, physiology, biochemistry and gene expression. Chronic UV-B radiation did not affect photosynthesis or the expression of stress responsive genes, which indicated that the UV-acclimated plants were not stressed. UV-induced morphological changes in acclimated plants included decreased rosette diameter, decreased inflorescence height and increased numbers of flowering stems, indicating that chronic UV-B treatment caused a redistribution rather than a cessation of growth. Gene expression profiling indicated that UV-induced morphogenesis was associated with subtle changes in phytohormone (auxins, brassinosteroids and gibberellins) homeostasis and the cell wall. Based on the comparison of gene expression profiles, it is concluded that acclimation to low, chronic dose rates of UV-B is distinct from that to acute, stress-inducing UV-B dose rates. Hence, UV-B-induced morphogenesis is functionally uncoupled from stress responses.