• ALGAE
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• v.21 no.1
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• pp.103-107
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• 2006

Rhodochorton purpureum 4187 from Jeju Island, Korea may have a sexual life history similar to that seen by other investigators working on other strains around the world. In culture short days (8:16, 11:13, 12:12 LD) at 10-15°C induced tetrasporogenesis. Discharged spores were observed with time lapse videomicroscopy. They showed a slight amoeboid movement for 2-3 minutes before rounding up and settling. Tetrasporelings develop into male and female gametophytes. No fertilisation was observed. Tetrasporangia often were borne on carpogonial clusters of females but no discharged spores were seen. Isolate 4241 from San Juan I., Washington, USA grew well in most conditions tested but did not reproduce in short days (8:16, 11:13, 12:12 LD) at 10-15°C.

• IMMUNE NETWORK
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• v.6 no.2
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• pp.76-85
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• 2006

Background: Chemotaxis is one of the cardinal functions of leukocytes, which enables them to be recruited efficiently to the right place at the right time. Analyzing chemotactic activities is important not only for the study on leukocyte migration but also for many other applications including development of new drugs interfering with the chemotactic process. However, there are many technical limitations in the conventional in vitro chemotaxis assays. Here we applied a new optical assay to investigate chemotactic activities induced in differentiated HL-60 cells. Methods: HL-60 cells were stimulated with 0.8% dimethylformamide (DMF) for 4 days. The cells were analyzed for morphology, flow cytometry as well as chemotactic activities by a time-lapse videomicroscopic assay using a chemotactic microchamber bearing a fibronectin-coated cover slip and an etched silicon chip. Results: Videomicroscopic observation of the real cellular motions in a stable concentration gradient of chemokines demonstrated that HL-60 cells showed chemotaxis to inflammatory chemokines (CCL3, CCL5 and CXCL8) and also a homeostatic chemokine (CXCL12) after DFM-induced differentiation to granulocytic cells. The cells moved randomly at a speed of $6.99{\pm}1.24{\mu}m/min$ (n=100) in the absence of chemokine. Chemokine stimulation induced directional migration of differentiated HL-60 cells, while they still wandered very much and significantly increased the moving speeds. Conclusion: The locomotive patterns of DMF-stimulated HL-60 cells can be analyzed in detail throughout the course of chemotaxis by the use of a time-lapse videomicroscopic assay. DMF-stimulated HL-60 cells may provide a convenient in vitro model for chemotactic studies of neutrophils.