HUMANIZED MODEL OF ISOLATED SUSPENSION CULTIVATION OF HEMATOPOIETIC PROGENITOR CELLS FOR THE INVESTIGATION OF IONIZING RADIATION INFLUENCE IN VIVO

Objective: development of the humanized system for cells cultivation outside the human organism (human–mouse) and investigation of the influence of ionizing radiation in increasing doses on the colony-forming ability of hematopoietic progenitor cells. Materials and methods. Bone marrow samples of individuals without blood system diseases were cultivated in gel diffusion chambers with semi-solid agar in the abdominal cavity of CBA mice exposed to ionizing radiation action. Cell aggregates, which were obtained in the culture of diffusion chambers in vivo, were counted and colony-forming efficiency of bone marrow cells was determined. Results. We revealed the stimulation of colony forming under the action of ionizing radiation in increasing doses on the animals-recipients of the chambers, which indirectly indicates the synthesis of colony-stimulating factor in the mice organism and its permeation into the diffusion chambers with human bone marrow cells. The effect of cytostatics action on the mice organism was investigated, which in experimentally selected dose cause stimulation of colony forming in cell cultures, both 24 hours and 2 hours after administration. Conclusions. The ability of hematopoietic progenitor cells of bone marrow to form colonies and clusters was evaluated during the cultivation in semi-solid agar in gel diffusion chambers in vivo, as well as the association with the number of explanted cells in the appropriate range was established, which indicates the clonal nature of cell aggregates growth in culture. It was shown that the treatment of animals the day prior to experiment with administration of cytostatics is comparable to the action of ionizing radiation and can be used to study hematopoiesis in «human–mouse» system. Key words: hematopoietic progenitor cells, internal roentgen radiation, cytostatics, cell culture in gel diffusion chambers in «human–mouse» system.

Metagenomic Evaluation of Bacterial and Fungal Assemblages Enriched within Diffusion Chambers and Microbial Traps Containing Uraniferous Soils

Despite significant technological advancements in the field of microbial ecology, cultivation and subsequent isolation of the vast majority of environmental microorganisms continues to pose challenges. Isolation of the environmental microbiomes is prerequisite to better understand a myriad of ecosystem services they provide, such as bioremediation of contaminants. Towards this end, in this culturomics study, we evaluated the colonization of soil bacterial and fungal communities within diffusion chambers (DC) and microbial traps (MT) established using uraniferous soils collected from a historically contaminated soil from Aiken, USA. Microbial assemblages were compared between the DC and MT relative to the native soils using amplicon based metagenomic and bioinformatic analysis. The overall rationale of this study is that DC and MT growth chambers provide the optimum conditions under which desired microbiota, identified in a previous study to serve as the “core” microbiomes, will proliferate, leading to their successful isolation. Specifically, the core microbiomes consisted of assemblages of bacteria (Burkholderia spp.) and fungi (Penicillium spp.), respectively. The findings from this study further supported previous data such that the abundance and diversity of the desired “core” microbiomes significantly increased as a function of enrichments over three consecutive generations of DC and MT, respectively. Metagenomic analysis of the DC/MT generations also revealed that enrichment and stable populations of the desired “core” bacterial and fungal microbiomes develop within the first 20 days of incubation and the practice of subsequent transfers for second and third generations, as is standard in previous studies, may be unnecessary. As a cost and time cutting measure, this study recommends running the DC/MT chambers for only a 20-day time period, as opposed to previous studies, which were run for months. In summation, it was concluded that, using the diffusion chamber-based enrichment techniques, growth of desired microbiota possessing environmentally relevant functions can be achieved in a much shorter time frame than has been previously shown.

Uncertainty in counting ice nucleating particles with continuous flow diffusion chambers

This study investigates the measurement of ice nucleating particle (INP) concentrations and sizing of crystals using continuous flow diffusion chambers (CFDCs). CFDCs have been deployed for decades to measure the formation of INPs under controlled humidity and temperature conditions in laboratory studies and by ambient aerosol populations. These measurements have, in turn, been used to construct parameterizations for use in models by relating the formation of ice crystals to state variables such as temperature and humidity as well as aerosol particle properties such as composition and number. We show here that assumptions of ideal instrument behavior are not supported by measurements made with a commercially available CFDC, the SPectrometer for Ice Nucleation (SPIN), and the instrument on which it is based, the Zurich Ice Nucleation Chamber (ZINC). Non-ideal instrument behavior, which is likely inherent to varying degrees in all CFDCs, is caused by exposure of particles to different humidities and/or temperatures than predicated from instrument theory of operation. This can result in a systematic, and variable, underestimation of reported INP concentrations. We find here variable correction factors from 1.5 to 9.5, consistent with previous literature values. We use a machine learning approach to show that non-ideality is most likely due to small-scale flow features where the aerosols are combined with sheath flows. Machine learning is also used to minimize the uncertainty in measured INP concentrations. We suggest that detailed measurement, on an instrument-by-instrument basis, be performed to characterize this uncertainty.