scholarly journals ChipSeg: an automatic tool to segment bacteria and mammalian cells cultured in microfluidic devices

2020 ◽  
Author(s):  
Irene de Cesare ◽  
Criseida G. Zamora-Chimal ◽  
Lorena Postiglione ◽  
Mahmoud Khazim ◽  
Elisa Pedone ◽  
...  
Keyword(s):  
Feedback Control ◽  
Mammalian Cells ◽  
Microfluidic Devices ◽  
Time Lapse ◽  
Cell Types ◽  
External Feedback ◽  
Quantitative Measurements ◽  
External Feedback Control ◽  
Automatic Tool ◽  
Cells Cultured

ABSTRACTExtracting quantitative measurements from time-lapse images is necessary in external feedback control applications, where segmentation results are used to inform control algorithms. While such image segmentation applications have been previously reported, there is in the literature a lack of open-source and documented code for the community. We describe ChipSeg, a computational tool to segment bacterial and mammalian cells cultured in microfluidic devices and imaged by time-lapse microscopy. The method is based on thresholding and uses the same core functions for both cell types. It allows to segment individual cells in high cell-density microfluidic devices, to quantify fluorescence protein expression over a time-lapse experiment and to track individual cells. ChipSeg enables robust segmentation in external feedback control experiments and can be easily customised for other experimental settings and research aims.

scholarly journals ChipSeg: An Automatic Tool to Segment Bacterial and Mammalian Cells Cultured in Microfluidic Devices

ACS Omega ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 2473-2476 ◽  
Author(s):  
Irene de Cesare ◽  
Criseida G. Zamora-Chimal ◽  
Lorena Postiglione ◽  
Mahmoud Khazim ◽  
Elisa Pedone ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Microfluidic Devices ◽  
Automatic Tool ◽  
Cells Cultured

scholarly journals Towards automated control of embryonic stem cell pluripotency

2019 ◽  
Author(s):  
Mahmoud Khazim ◽  
Lorena Postiglione ◽  
Elisa Pedone ◽  
Dan L. Rocca ◽  
Carine Zahra ◽  
...  
Keyword(s):  
Stem Cells ◽  
Feedback Control ◽  
Control Strategies ◽  
Embryonic Stem ◽  
Culture Conditions ◽  
Automatic Regulation ◽  
Human Stem Cells ◽  
Fluorescent Reporter ◽  
External Feedback ◽  
External Feedback Control

AbstractMouse embryonic stem cells (mESCs) have been shown to exist in three distinct pluripotent states (ground, naïve and primed pluripotent states), depending on culture conditions. External feedback control strategies have been, so far, mainly used to automatically regulate gene expression in bacteria and yeast. Here, we exploit a microfluidics/microscopy platform and segmentation and external feedback control algorithms for the automatic regulation of pluripotency phenotypes in mESCs. We show feasibility of automatically controlling, in living mESCs, levels of an endogenous pluripotency gene, Rex1, through a fluorescent reporter, used as control output, and drugs commonly used to modulate pluripotency (i.e. MEK kinase and Gsk3β inhibitors) as control inputs. Our results will ultimately aid in the derivation of superior protocols for pluripotency maintenance and differentiation of mouse and human stem cells.

Ultrastructural Changes in Three Different Mammalian Cells Following Ultraviolet Laser Irradiation

1972 ◽  
Vol 30 ◽  
pp. 350-351
Author(s):  
K. Shankar Narayan ◽  
Kailash C. Gupta ◽  
Tohru Okigaki
Keyword(s):  
Ultraviolet Light ◽  
Mammalian Cells ◽  
Biological Effects ◽  
Survival Rates ◽  
Chinese Hamster ◽  
Cell Types ◽  
Differential Sensitivity ◽  
Ultrastructural Changes ◽  
Ultraviolet Laser

The biological effects of short-wave ultraviolet light has generally been described in terms of changes in cell growth or survival rates and production of chromosomal aberrations. Ultrastructural changes following exposure of cells to ultraviolet light, particularly at 265 nm, have not been reported.We have developed a means of irradiating populations of cells grown in vitro to a monochromatic ultraviolet laser beam at a wavelength of 265 nm based on the method of Johnson. The cell types studies were: i) WI-38, a human diploid fibroblast; ii) CMP, a human adenocarcinoma cell line; and iii) Don C-II, a Chinese hamster fibroblast cell strain. The cells were exposed either in situ or in suspension to the ultraviolet laser (UVL) beam. Irradiated cell populations were studied either "immediately" or following growth for 1-8 days after irradiation.Differential sensitivity, as measured by survival rates were observed in the three cell types studied. Pattern of ultrastructural changes were also different in the three cell types.

scholarly journals Structural basis for proficient oxidized ribonucleotide insertion in double strand break repair

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Joonas A. Jamsen ◽  
Akira Sassa ◽  
Lalith Perera ◽  
David D. Shock ◽  
William A. Beard ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Time Lapse ◽  
Strand Break ◽  
Structural Basis ◽  
End Joining ◽  
Strand Breaks ◽  
Nucleotide Pools ◽  
Nucleotide Insertion ◽  
Non Homologous End Joining

AbstractReactive oxygen species (ROS) oxidize cellular nucleotide pools and cause double strand breaks (DSBs). Non-homologous end-joining (NHEJ) attaches broken chromosomal ends together in mammalian cells. Ribonucleotide insertion by DNA polymerase (pol) μ prepares breaks for end-joining and this is required for successful NHEJ in vivo. We previously showed that pol μ lacks discrimination against oxidized dGTP (8-oxo-dGTP), that can lead to mutagenesis, cancer, aging and human disease. Here we reveal the structural basis for proficient oxidized ribonucleotide (8-oxo-rGTP) incorporation during DSB repair by pol μ. Time-lapse crystallography snapshots of structural intermediates during nucleotide insertion along with computational simulations reveal substrate, metal and side chain dynamics, that allow oxidized ribonucleotides to escape polymerase discrimination checkpoints. Abundant nucleotide pools, combined with inefficient sanitization and repair, implicate pol μ mediated oxidized ribonucleotide insertion as an emerging source of widespread persistent mutagenesis and genomic instability.

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