A flow cytometric method for estimating S-phase duration in plants.
Ontology highlight
ABSTRACT:
SUBMITTER: Mickelson-Young L
PROVIDER: S-EPMC5100020 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BACKGROUND: A useful application of flow cytometry is the investigation of cell receptor-ligand interactions. However such analyses are often compromised due to problems interpreting changes in ligand binding where the receptor expression is not constant. Commonly, problems are encountered due to cell treatments resulting in altered receptor expression levels, or when cell lines expressing a transfected receptor with variable expression are being compared. To overcome this limitation we have developed a Microsoft Excel spreadsheet that aims to automatically and effectively simplify flow cytometric data and perform statistical tests in order to provide a clearer graphical representation of results. RESULTS: To demonstrate the use and advantages of this new spreadsheet method we have investigated the binding of the transmembrane adhesion receptor CD44 to its ligand hyaluronan. In the first example, phorbol ester treatment of cells results in both increased CD44 expression and increased hyaluronan binding. By applying the spreadsheet method we effectively demonstrate that this increased ligand binding results from receptor activation. In the second example we have compared AKR1 cells transfected either with wild type CD44 (WT CD44) or a mutant with a truncated cytoplasmic domain (CD44-T). These two populations do not have equivalent receptor expression levels but by using the spreadsheet method hyaluronan binding could be compared without the need to generate single cell clones or FACS sorting the cells for matching CD44 expression. By this method it was demonstrated that hyaluronan binding requires a threshold expression of CD44 and that this threshold is higher for CD44-T. However, at high CD44-T expression, binding was equivalent to WT CD44 indicating that the cytoplasmic domain has a role in presenting the receptor at the cell surface in a form required for efficient hyaluronan binding rather than modulating receptor activity. CONCLUSION: Using the attached spreadsheets and instructions, a simple post-acquisition method for analysing bivariate flow cytometry data is provided. This method constitutes a straightforward improvement over the standard graphical output of flow cytometric data and has the significant advantage that ligand binding can be compared between cell populations irrespective of receptor expression levels.
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Project description:The current report describes a newly devised method for automatically scoring the incidence of rat hepatocyte micronuclei (MNHEP) via flow cytometry, with concurrent assessments of hepatocyte proliferation-frequency of Ki-67-positive nuclei, and the proportion of polyploid nuclei. Proof-of-concept data are provided from experiments performed with 6-week old male Crl:CD(SD) rats exposed to diethylnitrosamine (DEN) or quinoline (QUIN) for 3 or 14 consecutive days. Non-perfused liver tissue was collected 4 days after cessation of treatment in the case of 3-day studies, or 1 day after last administration in the case of 14-day studies for processing and flow cytometric analysis. In addition to livers, blood samples were collected one day after final treatment for micronucleated reticulocyte (MN-RET) measurements. Dose-dependent increases in MNHEP, Ki-67-positive nuclei, and polyploidy were observed in 3- and 14-day DEN studies. Both treatment schedules resulted in elevated %MNHEP for QUIN-exposed rats, and while cell proliferation effects were subtle, appreciable increases to normalized liver weights were observed. Whereas DEN caused markedly higher %MNHEP when exposure was extended to two weeks, QUIN-induced MNHEP were slightly increased with protracted dosing. Parallel microscopy-based MNHEP frequencies were highly correlated with flow cytometry-based measurements (four study/aggregate R2 ?=?0.80). No increases in MN-RET were seen in any of the four studies. Collectively, these results suggest liver micronuclei are amenable to an automated scoring technique that provides objective analyses and higher information content relative to conventional microscopy. Additional work is needed to expand the number and types of chemicals tested, identify the most advantageous treatment schedules, and test the transferability of the method. Environ. Mol. Mutagen. 59:176-187, 2018. © 2018 Wiley Periodicals, Inc.
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Project description:UnlabelledHomogeneity of cell populations is a prerequisite for the analysis of biochemical and molecular events during male gamete differentiation. Given the complex organization of the mammalian testicular tissue, various methods have been used to obtain enriched or purified cell populations, including flow cell sorting. Current protocols are usually time-consuming and may imply loss of short-lived RNAs, which is undesirable for expression profiling. We describe an optimized method to speed up the preparation of suitable testicular cell suspensions for cytometric analysis of different spermatogenic stages from rodents. The procedure takes only 15 min including testis dissection, tissue cutting, and processing through the Medimachine System (Becton Dickinson). This method could be a substitute for the more tedious and time-consuming cell preparation techniques currently in use.Electronic supplementary materialThe online version of this article (DOI:10.1007/s12575-009-9003-2) contains supplementary material, which is available to authorized users.
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Project description:BackgroundConventional protocols utilize core needle biopsy (CNB) or fine needle aspiration (FNA) to produce cell suspension for flow cytometry (FCM) is a diagnostic challenge for lymphoid malignancies. We aim to develop an alternative CNB rinsing technique (RT) to produce cell suspension for FCM during this mini-invasive procedure of CNB for lymphoma diagnosis.MethodsFNA and CNB specimens from the same lesion of 93 patients with suspected lymphoma were collected under the guidance of B-ultrasound simultaneously. The fresh CNB samples were prepared to cell suspension by RT for FCM immunophenotyping analysis (Group CNB-RT). Then, the CNB tissues after performing the RT process and the fresh FNA tissues were processed by conventional tissue cell suspension (TCS) technique to obtain the cell suspensions (Groups of CNB-TCS & FNA-TCS), respectively, as comparison. The diagnostic efficacies, as well as the concordances of the FCM results with reference to the morphologic diagnoses were compared in these three groups.ResultsRT could yield sufficient cells for FCM immunophenotyping analysis, though a lower cell numbers compared to TCS technique. The diagnostic concordance was comparable in group CNB-RT (91.1%) to the group CNB-TCS (88.9%) and group FNA-TCS (88.4%) (p = 0.819). The diagnostic sensitivity and specificity of CNB-RT (91.1%; 100%) was not inferior to that of CNB-TCS (88.9%; 100%) and FNA-TCS (88.4%; 98.8%).ConclusionsThis study shows the CNB-RT presented non-inferior diagnostic concordance and efficacy as compared to the TCS technique. CNB-RT has the potential to produce cell suspension for FCM immunophenotyping while preserving tissue for lymphoma diagnosis and research.
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