Key Aspects for Implementing ISO/IEC 17025 Quality Management Systems at Materials Science Laboratories

Implementing a quality management system based on the requirements specified in ISO/IEC 17025 standard at materials science laboratories is challenging, mainly due to two main factors: (i) the high technical complexity degree of some tests used for materials characterization and (ii) the fact that most materials science laboratories provide materials characterization tests and also carry out research and development activities. In this context, this chapter presents key subjects while implementing a quality management system at materials science laboratories and some considerations on strategies for effectively implementing such systems

Development of a DNA-dosimeter system for monitoring the effects of solar-ultraviolet radiation

Solar radiation sustains and affects all life forms on Earth. In recent years, the increase in environmental levels of solar-UV radiation due to depletion of the stratospheric ozone layer, as a result of anthropogenic emission of destructive chemicals, has highlighted serious issues of social concern. This becomes still more dramatic in tropical and subtropical regions, where the intensity of solar radiation is higher. To better understand the impact of the harmful effects of solar-UV radiation on the DNA molecule, we developed a reliable biological monitoring system based on the exposure of plasmid DNA to artificial UV lamps and sunlight. The determination and quanti. cation of different types of UV photoproducts were performed through the use of specific DNA repair enzymes and antibodies. As expected, a significant number of CPDs and 6-4PPs was observed when the DNA-dosimeter system was exposed to increasing doses of UVB radiation. Moreover, CPDs could also be clearly detected in plasmid DNA when this system was exposed to either UVA or directly to sunlight. Interestingly, although less abundant, 6-4PPs and oxidative DNA damage were also generated after exposure to both UVA and sunlight. These results confirm the genotoxic potential of sunlight, reveal that UVA may also produce CPDs and 6-4PPs directly in naked DNA and demonstrate the applicability of a DNA-dosimeter system for monitoring the biological effects of solar-UV radiation.FAPESP (Sao Paulo, Brazil)CNPq (Brasilia, Brazil

DNA Repair Mechanisms of Antarctic Marine Bacteria in Extreme Environments

<p>The Antarctic continent presents a myriad of extreme environmental conditions and a unique isolation from the impacts of human society. Organisms in this region face constant threats to their genetic material, with various agents capable of damaging the DNA molecule, including the potent ultraviolet radiation (UV) emanating from sunlight. Additionally, the harsh environmental factors, particularly the extremely low temperatures, further contribute to the challenge of maintaining DNA stability. As a result, Antarctica serves as a compelling setting for studying how organisms navigate the preservation of genome integrity in such harsh conditions. In this study, we aim to delve into the mechanisms employed by microorganisms to survive in the face of these extreme Antarctic environments. To achieve this, we have conducted genome sequencing of three Antarctic marine bacteria. Two of these bacteria were isolated from sediment samples at depths of 280 meters, while the third was retrieved from a depth of 1500 meters in the Bransfield Strait. Deeper sea conditions entail higher concentrations of CO2 under elevated atmospheric pressure, adding an additional layer of environmental challenge for these bacteria. The DNA extracted from these isolates was sequenced using the Illumina platform. Subsequently, we performed de novo genome assembly utilizing <i>SPAdes v3.15.4</i>, and assessed assembly metrics with <i>QUAST v5.2.0</i>. Genome completeness was evaluated using <i>BUSCO v5.3.1</i>. Furthermore, we conducted annotation via the Prokaryotic Genome Annotation Pipeline (PGAP) and identified the species based on the 16S ribosomal RNA (rRNA) sequence, employing the software <i>GTDB-Tk 2.1.0</i>. Additionally, we scrutinized the presence of DNA repair genes in these organisms using blastp, with hits meeting criteria of e-value < 1E-5, coverage > 60%, and identity > 30% considered as orthologs. Hits not meeting these criteria had their conserved protein domains analyzed on InterPro to capture potential false-negatives. Preliminary findings indicate that the majority of DNA repair genes are indeed present in these bacteria, suggesting a diverse array of strategies they employ to combat DNA damage. Notably, nucleotide excision repair emerged as the most conserved pathway in these bacteria. These results underscore the significance of repair pathways involved in the removal of sunlight-induced lesions, indicating their crucial role in maintaining genome integrity in an environment characterized by high levels of UV radiation.</p&gt

Antibacterial T6SS effectors with a VRR-Nuc domain are structure-specific nucleases

The type VI secretion system (T6SS) secretes antibacterial effectors into target competitors. Salmonella spp. encode five phylogenetically distinct T6SSs. Here, we characterize the function of the SPI-22 T6SS of Salmonella bongori showing that it has antibacterial activity and identify a group of antibacterial T6SS effectors (TseV1–4) containing an N-terminal PAAR-like domain and a C-terminal VRR-Nuc domain encoded next to cognate immunity proteins with a DUF3396 domain (TsiV1–4). TseV2 and TseV3 are toxic when expressed in Escherichia coli and bacterial competition assays confirm that TseV2 and TseV3 are secreted by the SPI-22 T6SS. Phylogenetic analysis reveals that TseV1–4 are evolutionarily related to enzymes involved in DNA repair. TseV3 recognizes specific DNA structures and preferentially cleave splayed arms, generating DNA double-strand breaks and inducing the SOS response in target cells. The crystal structure of the TseV3:TsiV3 complex reveals that the immunity protein likely blocks the effector interaction with the DNA substrate. These results expand our knowledge on the function of Salmonella pathogenicity islands, the evolution of toxins used in biological conflicts, and the endogenous mechanisms regulating the activity of these toxins

Review of 21 cases of mycetoma from 1991 to 2014 in Rio de Janeiro, Brazil

Submitted by Janaína Nascimento ([email protected]) on 2019-07-22T13:08:15Z No. of bitstreams: 1 ve_Sampaio_Felipe_etal_INI_2017.pdf: 1737175 bytes, checksum: b56b57983669486175819846a0001025 (MD5)Approved for entry into archive by Janaína Nascimento ([email protected]) on 2019-07-22T13:19:09Z (GMT) No. of bitstreams: 1 ve_Sampaio_Felipe_etal_INI_2017.pdf: 1737175 bytes, checksum: b56b57983669486175819846a0001025 (MD5)Made available in DSpace on 2019-07-22T13:19:09Z (GMT). No. of bitstreams: 1 ve_Sampaio_Felipe_etal_INI_2017.pdf: 1737175 bytes, checksum: b56b57983669486175819846a0001025 (MD5) Previous issue date: 2017Fundação Oswaldo Cruz. Instituto Nacional de Infectologia Evandro Chagas. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Nacional de Infectologia Evandro Chagas. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Nacional de Infectologia Evandro Chagas. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Nacional de Infectologia Evandro Chagas. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Nacional de Infectologia Evandro Chagas. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Nacional de Infectologia Evandro Chagas. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Nacional de Infectologia Evandro Chagas. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Nacional de Infectologia Evandro Chagas. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Nacional de Infectologia Evandro Chagas. Rio de Janeiro, RJ, Brasil.Mycetoma is caused by the subcutaneous inoculation of filamentous fungi or aerobic filamentous bacteria that form grains in the tissue. The purpose of this study is to describe the epidemiologic, clinic, laboratory, and therapeutic characteristics of patients with mycetoma at the Oswaldo Cruz Foundation in Rio de Janeiro, Brazil, between 1991 and 2014. Twenty-one cases of mycetoma were included in the study. There was a predominance of male patients (1.3:1) and the average patient age was 46 years. The majority of the cases were from the Southeast region of Brazil and the feet were the most affected anatomical region (80.95%). Eumycetoma prevailed over actinomycetoma (61.9% and 38.1% respectively). Eumycetoma patients had positive cultures in 8 of 13 cases, with isolation of Scedosporium apiospermum species complex (n = 3), Madurella mycetomatis (n = 2) and Acremonium spp. (n = 1). Two cases presented sterile mycelium and five were negative. Six of 8 actinomycetoma cases had cultures that were identified as Nocardia spp. (n = 3), Nocardia brasiliensis (n = 2), and Nocardia asteroides (n = 1). Imaging tests were performed on all but one patients, and bone destruction was identified in 9 cases (42.68%). All eumycetoma cases were treated with itraconazole monotherapy or combined with fluconazole, terbinafine, or amphotericin B. Actinomycetoma cases were treated with sulfamethoxazole plus trimethoprim or combined with cycles of amikacin sulphate. Surgical procedures were performed in 9 (69.2%) eumycetoma and in 3 (37.5%) actinomycetoma cases, with one amputation case in each group. Clinical cure occurred in 11 cases (7 for eumycetoma and 4 for actinomycetoma), and recurrence was documented in 4 of 21 cases. No deaths were recorded during the study. Despite of the scarcity of mycetoma in our institution the cases presented reflect the wide clinical spectrum and difficulties to take care of this neglected disease

Radiography showing bone destruction.

<p>Radiography showing bone destruction.</p

HIV patient with actinomycetoma after treatment.

<p>HIV patient with actinomycetoma after treatment.</p

Right foot affected with actinomycetoma after treatment.

<p>Right foot affected with actinomycetoma after treatment.</p

Right foot affected with actinomycetoma and the left foot without disease.

<p>Right foot affected with actinomycetoma and the left foot without disease.</p