1997 Fiscal Year Final Research Report Summary
Chemical studies on plant cell growth factors of monocots and dicots
| Project/Area Number |
08456169
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied molecular and cellular biology
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| Research Institution | Nagoya University |
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Principal Investigator |
SAKAGAMI Youji Nagoya University, Department of Applied Biological Sciences, Professor, 農学部, 教授 (80107408)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Asparagus / Plant cell growth factor / Phytosulfokine / Conditioned medium / Binding site |
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| Research Abstract |
The cell proliferation of mechanically isolated asparagus mesophyll cells is very low at low cell densities. The conditioned medium from rapidly growing cells at high cell density stimulated well the cell proliferation of low cell density culture. Using this system, we isolated two plant cell growth factors. These two factors were peptides having five or four amino acids residues and side chains of two tyrosine residues were sulfated. Thus, we named these factors phytosulfokine-a and b (PSK-a and b). PSK-a and PSK-b showed biological activity at the concentration of 10-9 M and 10-8 respectively. Various kinds of PSK derivatives were synthesized and three amino acid residues at the amino terminal are important to be a biologically active peptide. PSK was also identified in condetioned media of monocots, rice and maize as a plant cell growth factor. We synthesized radio active PSK-a which sulfur atoms of sulfates was labeled by radio isotopes. Using this labeled peptide, we investigated the binding assay with asparagus mesoopyll cell and rice Oc cell line. Both cells showed the binding ability, but Oc cells had ten times higher ability. From the precise binding experiments with Oc cells, there are two binding sites specific to PSK and these cites are contained in the membrane fraction. The difference between monocots and dicots growth factor was suggested by past studies. Therefore, we investigate the plant cell growth factor of dicots using Zinea. PSK,however, was identified from the conditioned medium of Zinea as a growth factor. Thus PSK seems to be a general growth factor in plants.
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