Various studies, including morpho-taxonomic identifications, have indicated that commercial spirulina cultures (Limnospira spp.) can be contaminated by other cyanobacteria without establishing a connection with the potential presence of cyanotoxins. The taxonomy and nomenclature of cyanobacteria has changed significantly since the usage of phylogenetic methods and reclassification could lead to confusion in the designation of taxa previously identified as toxin producers. It therefore appears necessary to characterize the cyanosphere of commercial spirulina cultures in the light of these recent developments. In a collection of six spirulina cultivars used in commercial biomass production, we detected a recurrent dominant cyanobacterial contaminant using 16S rRNA gene amplicon sequencing. Further, Next-Generation Sequencing as well as genetic and morphological characterization pointed towards the genus Sodalinema. A comprehensive analysis of five Sodalinema available genomes as well as our novel metagenome-assembled genome did not reveal any genes involved in the synthesis of cyanotoxins, which suggested that this contaminant is harmless. Still, to avoid valuable biomass related financial loss, we took advantage of spirulina capacity to utilize various forms of nitrogen to set up a procedure to control the proliferation of Sodalinema sp. Finally, a glimpse into heterotrophic contamination of those cultivars indicated that the bacterial composition is very diverse but still several phyla appeared to be very common in open-pond cultivation of spirulina in the Mediterranean region.
BACKGROUND:Intensity modulated proton therapy (IMPT) is the preferred option during pregnancy, as it reduces out-of-field doses compared to photon techniques. A physical pregnancy phantom was validated for in-field proton dosimetry and used to assess fetal dose across four IMPT plans. METHODS:The 18-week pregnancy Tena phantom was composed of bone, soft tissue, and lung substitutes. Proton relative stopping power (RSP) for Tena tissues was measured and compared with treatment planning system (TPS) and Monte Carlo (MC) calculations. Experimental TPS dose verification was performed using gamma index (GI). Fetal dose was measured for IMPT of glioma, Hodgkin lymphoma without (HL) and with a range shifter (HL-RS), and submandibular gland (neck) cancer using a Timepix and bubble detectors. RESULTS:Differences between TPS-assigned and MC-simulated relative to the measured RSP values were up to -7.4 %. GI(3 %/3 mm) values were above 93.38 %. The neutron dose equivalent in the fetus position ranged between 2.5 and 49.4 µSv/Gy(RBE) for glioma and HL-RS plans, respectively. The HL plan reduced neutron dose equivalent to 15.8 µSv/Gy(RBE), while for the neck 20 µSv/Gy(RBE) was measured. Neutrons were dominant with ∼ 80 % contribution to the total dose equivalent. A summed fetal dose was calculated considering the prescribed dose per treatment and ranged between 0.17 mSv and 1.89 mSv for glioma and HL-RS, respectively. CONCLUSIONS:The Tena phantom is suitable for proton dosimetry and enables accurate TPS calculations. The use of a range shifter increased the fetal dose by more than threefold. Fetal doses for all IMPT plans remained below 2 mSv.
Background: Improvement in radiation protection practice may be achieved by acquisition of reliable and accurate dosimetry data. Use of dosimeters with known properties provides insight into their performance in real radiation fields encountered in radiation monitoring practice. Aim: Performance evaluation in a wide range of radiation conditions provides insight into dosimeter behaviour, providing input for revision, update and harmonization of IEC type testing standards. Methods: A total of 32 active dosimeters were investigated, of which 26 are used for area workplace, and 6 for individual monitoring. Dosimeter performance was evaluated against the IEC 60846-1:2009 standard for portable workplace and environmental meters and monitors and the IEC 61526:2024 standard for active personal dosimeters in a wide range of photon energies, angles of incidence and dose equivalent rates. Performance was examined beyond the minimum rated range: 33.3 keV-1.25 MeV photon energy; (0 degrees; +/- 75 degrees) angle of incidence for personal dosimeters and (0 degrees; +/- 120 degrees with 180 degrees) for area dosimeters; 3 mu Sv h-1-7 Sv h-1 dose rate range. In addition, dosimeter short-term stability and overload properties were investigated. Results: State-of-the-art and commonly used dosimeters complied with the standard defined limits of variation with respect to the manufacturer stated specifications. Some dosimeters had significantly lower variations in terms of relative response than the current standard stated requirements. Conclusion: Potential update of the relevant IEC type testing standards was considered, with the possibility of introducing two distinct dosimeter classes, one of which would comply with reduced limits of variation.
Mass measurements of the ground and isomeric states of ^68-70Co have been performed using the JYFLTRAP Penning-trap mass spectrometer at the IGISOL facility. The masses were measured, either for the first time for the isomeric states of ^68Co and ^70Co, or with greatly improved precision for the others, removing ambiguities in the mass surface beyond N=40. The ordering of the low and high-spin states in ^68Co and ^70Co has also been established. The results, supported by Large-Scale Shell Model and Discrete Non-Orthogonal Shell-Model calculations, show a gradual lowering of intruder states with increasing neutron number, eventually leading to an inversion in ^70Co. These findings clarify previously proposed contradictory interpretations. Finally, we demonstrate the importance of including induced effective 3N forces for a consistent description of binding energies in the island of inversion near N=40.
Abstract Background Conifers like Scots pine ( Pinus sylvestris ) are a potential bioindicator species for radioactive contamination as they are among the most radiosensitive plant species. Phytohormones and amino acids are central to plant growth and stress signaling, but their roles in the pine radiation response, particularly in a tissue-specific context, have not been adequately studied. Results Here, we investigated the morphological, metabolic and transcriptional consequences of chronic gamma irradiation in pine seedlings under controlled laboratory conditions. We exposed P. sylvestris seedlings to 10 weeks of low-dose external gamma irradiation (682 µGy/h) and performed targeted metabolomic analysis of phytohormones and amino acids and RT-qPCR analysis of hormone-related gene expression in the shoot tip, root tip, young needles, and cotyledons, alongside a microscopic analysis of the shoot apical meristem. Irradiation induced a significant reduction in the height and area of the meristem. This morphological change coincided with a trend towards decreased abundance of growth-promoting hormones in the shoot tip, namely cytokinins and gibberellins. Our data also indicate the potential involvement of specific cytokinin and gibberellin signals in the young needles in the response to irradiation, and hint towards a tissue-specific role for jasmonyl-ACC conjugation in the young shoot. Concurrently, the cotyledons of irradiated seedlings displayed a massive and significant increase in free amino acid concentrations and decreased cytokinin abundance, consistent with accelerated senescence. Conclusions Taken together, these results reveal a tissue-specific pattern of metabolic and transcriptional changes in irradiated pine seedlings. The data are consistent with a scenario in which apical growth is hormonally suppressed and resources may be liberated from cotyledon tissue, which could then potentially be reallocated toward a stress response in developing organs. This study thereby provides an integrated view of the organ-level metabolic response to chronic radiation.
