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L Voet

Publications and source records attributed to L Voet.

8 recordsLinked to original sources
PubMed1985

Flow cytometer study of anterior-like cells in Dictyostelium discoideum.

The Dictyostelium discoideum asexual fruiting body consists of spores, stalk and basal disk cells. Recently, a fourth cell class has been proposed. It has been suggested that these cells originate from anterior-like cells that remain undifferentiated. Anterior-like cells are randomly distributed among prespore cells in the posterior part of the slug. Here monoclonal antibodies that recognize the surface of prespore cells (MUD1), and spores (MUD3) are used in a quantitative flow cytometer assay to demonstrate that this fourth cell class does not exist in the mature fruiting body. However, the tip cells are slow to differentiate, and hence immature fruiting bodies contain a small population of undifferentiated tip cells. We confirm that anterior-like cells represent a large percentage of the non-prespore cell population in the slug. In this report we were unable to distinguish these anterior-like cells from prestalk cells on the basis of size or monoclonal antibody staining.

Antibodies, Monoclonal↗
PubMed1985

Use of a monoclonal antibody recognizing a cell surface determinant to distinguish prestalk and prespore cells of Dictyostelium discoideum slugs.

Double labelling experiments on Dictyostelium discoideum cells at different developmental stages were carried out using monoclonal antibodies MUD1 (prespore specific), MUD9 (strong label on prestalk and anterior-like cells) and a fluorescence-activated cell sorter. The monoclonal antibody MUD9, which recognizes the surface of prestalk and anterior-like cells strongly and prespore cells weakly, is also present on the surface of vegetative amoebae and on mature stalk cells but not on the spore surface. Sharing of an antigenic determinant between vegetative, prestalk and anterior-like cells is consistent with these cells being 'less differentiated' than prespore cells.

Antibodies, Monoclonal↗
PubMed1984

An assay for pattern formation in dictyostelium discoideum using monoclonal antibodies, flow cytometry, and subsequent data analysis.

An assay for determining the proportions of prespore cells in a simple multicellular organism, the slug stage of Dictyostelium discoideum, was established using a prespore-specific monoclonal antibody and a fluorescence-activated cell sorter. Appropriate techniques for data analysis were developed. The effects of slug size and age were determined. Small slugs have a lower percentage of prespore cells than large slugs. The percentage of prespore cells increases and then decreases in slugs aged between a few hours and 9 days. Pronounced effects were observed on the size of cells in aging slugs. In particular unlabelled (mostly prestalk) cells were larger than prespore cells in young slugs, but after 6 days migration they became considerably smaller than prespore cells. The fact that all unlabelled cells were coordinately shifted in size, suggests that these cells (which comprise prestalk, prestalklike, and predisc cells) are related to each other.

Antibodies, Monoclonal↗
PubMed1983

Analysis of proportion regulation in slugs of Dictyostelium discoideum using a monoclonal antibody and a FACS-IV.

A quantitative assay for estimating the proportion of prespore cells in D. discoideum slugs was established by labelling disaggregated slug cells with a prespore specific monoclonal antibody and analysing the cell population with a FACS-IV. The method is validated using a wild-type strain and its stalky mutant. "Wild-type" strains have different proportions of prespore cells and it is demonstrated that slugs of some strains have an increased percentage of prespore cells when migrated in the dark compared to the light and in the presence of EGTA. The technique is rapid and will make possible genetic analysis of proportion regulation in D. discoideum.

Antibodies, Monoclonal↗
PubMed1982

Data acquisition and control system for multiparameter cell sorting based on DEC LSI-11 microprocessor.

A computer system has been developed to add data acquisition, display, storage, and processing capability to a multiparamenter flow cytometer/sorter. The system can handle one or two parameters in histogram mode. Alternatively one, two or more parameters are stored event-by-event on an external storage device in list-mode with a resolution of 12 bit. The processor can also control cell sorting. Usual multichannel analyzer features are implemented in software, using standard interface boards without special electronics. Data are accepted via Direct Memory Access (DMA), which depends only on hardware. Data acquisition deadtime is nearly independent of software routines such as graphics display and interactive work. Since more than 8000 events/sec are achieved for eight paramenter handling, the computer system has capacity for rapid data acquisition. Although there is no need for such high data acquisition rates in present flow cytometry, it gives the advantage of short single event acquisition and longer process control handling.

Cell Separation↗
PubMed1979

Cytofluorometric analysis of R-Thy-1. antigens in various rat lymphocytes with different electrophoretic mobility and organ distribution.

Small bone marrow lymphocytes, which had been previously enriched by velocity sedimentation, thymocytes, lymph node cells and spleen cells were electrophoretically separated, stained with fluorescein conjugated rabbit a-rat-Thy-1. globulin and their fluorescence intensities analyzed with a flow cytophotometer. Thy-1. antigens were found in 80% of the bone marrow small lymphocytes showing low electrophoretic mobility (EPM), in all thymocytes, about 80% of which show low and the rest medium to high EPM, and in a few lymph node cells of high EPM. Thy-1. positive cells were not observed in the spleen. All fluorescence intensity histograms obtained were modal and could be properly fitted with normal curves showing coefficients of variation (C.V.) in the range of 20% to 30%. It was observed that the thymocytes of low EPM had an antibody binding affinity significantly different from that of the other stained lymphocytes. Moreover the surface antigen density decreased in the sequence: thymocytes of low EPM, bone marrow lymphocytes of low EPM and thymocytes of high EPM. The fluorescence intensity of stained lymph node cells of high EPM appeared similar to that of thymocytes of high EPM but was not evaluated precisely. Thus the two dimensional cell analysis provided by a combination of EPM and surface fluorescence of Thy-1.+ cells, allows the characterization of different lymphocyte populations which cannot be clearly identified with normal one dimensional techniques. The biological significance of the results is discussed briefly.

Animals↗