L'antitesi Diocleziano-martiri nel cristianesimo copto

A cura di Gherardo Gnoli e Giulia Sfameni Gasparro

Evaluation of NAD(+)-dependent DNA ligase of mycobacteria as a potential target for antibiotics

Mycobacteria contain genes for several DNA ligases, including ligA, which encodes a NAD+-dependent enzyme that has been postulated to be a target for novel antibacterial compounds. Using a homologous recombination system, direct evidence is presented that wild-type ligA cannot be deleted from the chromosome of Mycobacterium smegmatis. Deletions of native ligA in M. smegmatis could be obtained only after the integration of an extra copy of M. smegmatis or Mycobacterium tuberculosis ligA into the attB site of the chromosome, with expression controlled by chemically inducible promoters. The four ATP-dependent DNA ligases encoded by the M. smegmatis chromosome were unable to replace the function of LigA. Interestingly, the LigA protein from M. smegmatis could be substituted with the NAD+-dependent DNA ligase of Escherichia coli or the ATP-dependent ligase of bacteriophage T4. The conditional mutant strains allowed the analysis of the effect of LigA depletion on the growth of M. smegmatis. The protein level of the conditional mutants was estimated by Western blot analysis using antibodies raised against LigA of M. tuberculosis. This revealed that a strong overproduction or depletion of LigA did not affect the growth or survival of mycobacteria under standard laboratory conditions. In conclusion, although NAD+-dependent DNA ligase is essential for mycobacterial viability, only low levels of protein are required for growth. These findings suggest that very efficient inhibition of enzyme activity would be required if NAD+-dependent DNA ligase is to be useful as an antibiotic target in mycobacteria. The strains developed here will provide useful tools for the evaluation of the efficacy of any appropriate compounds in mycobacteria

Aquatic Animal Health Training Scheme. Fish disease diagnosis, biosecurity & disease management training for fish farming industry of Australia.

This workshop delivered new knowledge and technical skills with hands-on training to 24 participants representing of Australian fish-farming and government veterinarian sectors. The workshop focused on delivering training in both theory and practical aspects, with delivering hands-on technical skills, relating directly to fish disease detection, diagnosis, treatment, control, disease emergency response, disease reporting, fish health certification, fish toxicology and fish kills. The workshop was held in Townsville, Queensland on July 17th-18th, 2015, and was organized and delivered by Dr Rachel Bowater, Mr Andrew Fisk, Dr Kitman Dyrting, Dr Ian Anderson and Dr Roger Chong, with whom collectively have >100 years of experience in fish diagnostics, research, pathology, policy and aquaculture extension

Development and Evaluation of an Undergraduate Science Communication Module

This paper describes the design and evaluation of an undergraduate final year science communication module for the Science Faculty at the University of East Anglia. The module focuses specifically on science communication and aims to bring an understanding of how science is disseminated to the public. Students on the module are made aware of the models surrounding science communication and investigate how the science culture interfaces with the public. During the module they learn how to adapt science concepts for different audiences and how to talk confidently about science to a lay-audience. Student motivation for module choice centres on the acquisition of transferable skills and students develop these skills through designing, running and evaluating a public outreach event at a school or in a public area. These transferable skills acquired include communication, interaction with different organisations such as museums and science centres, developing understanding of both the needs of different audiences and the importance of time management. They also develop skills relating to self-reflection and how to use this as a tool for future self development. The majority of students completing the module go on to further study, either a PhD, MSc or teacher training. The module can be sustained in its present formed if capped at 40 students, however it is recognised that to increase cohort size, further investment of faculty time and resources would be required

Procedures for the salvage and necropsy of the Dugong (Dugong Dugon)-second edition 2007

This manual provides a detailed guide for dugong (Dugong dugon) carcass handling and necropsy procedures. It is intended to be used as a resource and training guide for anyone involved in dugong incidents including management officers, biologists, parks and wildlife field staff, and veterinarians and pathologists who may lack dugong expertise. Because of the wide range of professionals this book is targeting, information and the use of technical terms is extensive. Section 8.0 provides definitions of various terms used which are italicised throughout the text

Direct comparison of nick-joining activity of the nucleic acid ligases from bacteriophage T4

The genome of bacteriophage T4 encodes three polynucleotide ligases, which seal the backbone of nucleic acids during infection of host bacteria. The T4Dnl (T4 DNA ligase) and two RNA ligases [T4Rnl1 (T4 RNA ligase 1) and T4Rnl2] join a diverse array of substrates, including nicks that are present in double-stranded nucleic acids, albeit with different efficiencies. To unravel the biochemical and functional relationship between these proteins, a systematic analysis of their substrate specificity was performed using recombinant proteins. The ability of each protein to ligate 20 bp double-stranded oligonucleotides containing a single-strand break was determined. Between 4 and 37 °C, all proteins ligated substrates containing various combinations of DNA and RNA. The RNA ligases ligated a more diverse set of substrates than T4Dnl and, generally, T4Rnl1 had 50-1000-fold lower activity than T4Rnl2. In assays using identical conditions, optimal ligation of all substrates was at pH 8 for T4Dnl and T4Rnl1 and pH 7 for T4Rnl2, demonstrating that the protein dictates the pH optimum for ligation. All proteins ligated a substrate containing DNA as the unbroken strand, with the nucleotides at the nick of the broken strand being RNA at the 3'-hydroxy group and DNA at the 5'-phosphate. Since this RNA-DNA hybrid was joined at a similar maximal rate by T4Dnl and T4Rnl2 at 37 °C, we consider the possibility that this could be an unexpected physiological substrate used during some pathways of 'DNA repair'

Partial anomalous pulmonary venous drainage in patients presenting with suspected pulmonary hypertension: A series of 90 patients from the ASPIRE registry

Background and objective There are limited data regarding patients with PAPVD with suspected and diagnosed PH. Methods Patients with PAPVD presenting to a large PH referral centre during 2007–2017 were identified from the ASPIRE registry. Results Ninety patients with PAPVD were identified; this was newly diagnosed at our unit in 71 patients (78%), despite 69% of these having previously undergone CT. Sixty‐seven percent had a single right superior and 23% a single left superior anomalous vein. Patients with an SV‐ASD had a significantly larger RV area, pulmonary artery and L‐R shunt and a higher % predicted DLCO (all P  3 WU. Seven of these patients had isolated PAPVD, five of whom (8% of those patients with PH) had anomalous drainage of a single pulmonary vein. Conclusion Undiagnosed PAPVD with or without ASD may be present in patients with suspected PH; cross‐sectional imaging should therefore be specifically assessed whenever this diagnosis is considered. Radiological and physiological markers of L‐R shunt are higher in patients with an associated SV‐ASD. Although many patients with PAPVD and PH may have other potential causes of PH, a proportion of patients diagnosed with PAH have isolated PAPVD in the absence of other causative conditions

Real-time detection of cruciform extrusion by single-molecule DNA nanomanipulation

During cruciform extrusion, a DNA inverted repeat unwinds and forms a four-way junction in which two of the branches consist of hairpin structures obtained by self-pairing of the inverted repeats. Here, we use single-molecule DNA nanomanipulation to monitor in real-time cruciform extrusion and rewinding. This allows us to determine the size of the cruciform to nearly base pair accuracy and its kinetics with second-scale time resolution. We present data obtained with two different inverted repeats, one perfect and one imperfect, and extend single-molecule force spectroscopy to measure the torque dependence of cruciform extrusion and rewinding kinetics. Using mutational analysis and a simple two-state model, we find that in the transition state intermediate only the B-DNA located between the inverted repeats (and corresponding to the unpaired apical loop) is unwound, implying that initial stabilization of the four-way (or Holliday) junction is rate-limiting. We thus find that cruciform extrusion is kinetically regulated by features of the hairpin loop, while rewinding is kinetically regulated by features of the stem. These results provide mechanistic insight into cruciform extrusion and help understand the structural features that determine the relative stability of the cruciform and B-form states

Biophysical and electrochemical studies of protein-nucleic acid interactions

This review is devoted to biophysical and electrochemical methods used for studying protein-nucleic acid (NA) interactions. The importance of NA structure and protein-NA recognition for essential cellular processes, such as replication or transcription, is discussed to provide background for description of a range of biophysical chemistry methods that are applied to study a wide scope of protein-DNA and protein-RNA complexes. These techniques employ different detection principles with specific advantages and limitations and are often combined as mutually complementary approaches to provide a complete description of the interactions. Electrochemical methods have proven to be of great utility in such studies because they provide sensitive measurements and can be combined with other approaches that facilitate the protein-NA interactions. Recent applications of electrochemical methods in studies of protein-NA interactions are discussed in detail