title: Intracellular protein and nucleic acid measured in eight cell types using deep-ultraviolet mass mapping.
abstract: We present measurements by deep-ultraviolet mass mapping of nucleic acid (NA) and protein for five commonly cultured and three primary cell types. The dry mass distribution at submicron resolution was determined on a single-cell basis for 250-500 cells from each of these types. Since the method carries a direct reference to a spectrophotometric standard (molar extinction coefficient), we are able to calibrate the absolute weight distributions both on a cell-to-cell basis within each type and across types. We also provide a calibration in absolute mass units for fluorescence-based measurements (flow cytometry and fluorescence microscopy). As might be expected the cultured cell lines show a high concentration of nucleic acids in the nuclear compartment, much larger than the genomic 2C number even in the G1 stage. The whole-cell nucleic-acid/protein ratio was found to be a characteristic of cell lines that persists independent of cell cycle and, as a result, this ratio has some value for phenotyping. Primary chicken red blood cells (cRBC), often used as a cytometry standard, were determined to have a nuclear-isolated nucleic acid content much closer to the genomic number than the cultured cell lines (cRBC: 3.00 pg total NA, 2.30 pg DNA, and 0.70 pg RNA). The individual blastomeres (n = 54) from mouse embryos at eight-cell stage were measured and found to vary by more than a factor or two in total protein and nucleic acid content (0.8-2.3 ng total protein, 70-150 pg total NA). The ratio of nucleic acid to protein was more nearly constant for each blastomere from a particular embryo and this ratio was found to be an identifying characteristic that varies from embryo to embryo obtained from a single flushing of a mouse.
authors.affiliation: Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, USA. mc.cheung@gmail.com
authors.forename: Man C
authors.initials: MC
authors.lastname: Cheung
authors.forename: Rebecca
authors.initials: R
authors.lastname: LaCroix
authors.forename: Brian K
authors.initials: BK
authors.lastname: McKenna
authors.forename: Ling
authors.initials: L
authors.lastname: Liu
authors.forename: James
authors.initials: J
authors.lastname: Winkelman
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Ehrlich
mesh_terms: D000818:Animals; D001757:Blastomeres / Q000737:chemistry / Q000166:cytology; D016466:CHO Cells; D002138:Calibration; D045744:Cell Line, Tumor; D002645:Chickens; D003412:Cricetulus; D004247:DNA / Q000032:analysis*; D004622:Embryo, Mammalian / Q000737:chemistry / Q000166:cytology; D004912:Erythrocytes / Q000737:chemistry / Q000166:cytology; D005434:Flow Cytometry; D006801:Humans; D051379:Mice; D008856:Microscopy, Fluorescence; D041681:NIH 3T3 Cells; D011506:Proteins / Q000032:analysis*; D012313:RNA / Q000032:analysis*; D059010:Single-Cell Analysis
chemical_list: D011506:Proteins; D012313:RNA; D004247:DNA