Anatomy of the thermosensory mechanisms in C. elegans
| Project/Area Number |
11694215
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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 |
Biophysics
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
OHSHIMA Yasumi Kyushu University, Dept of Biology, Professor, 大学院・理学研究院, 教授 (90037606)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥5,900,000 (Direct Cost: ¥5,900,000)
Fiscal Year 2001: ¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 2000: ¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1999: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Keywords | Nematode C. elegans / Thermotaxis / Thermosensation / ttx-1 gene / ttx-2 gene / ttx-3 gene / AFD neuron / Movement analysis / 線虫C.elegans / C.elegans / ttx-2 / ttx-1 |
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| Research Abstract |
(1) Analysis of ttx-1 gene : Cryophilic mutation ttx-1 (p767) was mapped between unc-51 and rol-9 on LGV, and YAC clone Y113G7 rescued the phenotype of ttx-1. However, further attempts were withdrawn since P. Segupta informed us that ttx-1 gene had been clond in her laboratory. (2) Analysis of ttx-2 gene : Cryophlic mutation ttx-2 (ks 4) was mapped between dpy-17 and lon-1 on LGIII. Thermotaxis defect of ttx-2 was rescued with either YAC Y32H12, cosmid W03A5 or an 11kb fragment of W03A5. Strains deleting either of two ORFs. W03A5.1+5.2 and Y32H12A.8 were isolated by S. Mitani, and their phenotypes were normal. These results may suggest that ttx-2 gene is one of other ORFs in the YAC. (3) Analysis of the thermotaxis behavior : To analyze thermal responses of Caenorhabditis elegans in detail, distribution of a worm population and movement of individual worms were examined on a linear, reproducible and broad temperature gradient. Assay methods were improved also to ensure good motility an
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d dispersion of worms. Well fed worms distributed over a wide temperature range of up to 10 ℃, and within this range worms migrated in both directions of the gradient at similar frequencies, without any specific response to the growth temperature. In contrast, worms migrated down the gradient if put in a region warmer than the warm boundary. The distribution range changed depending on the growth temperature and starvation, but active avoidance of a starvation temperature was not detected. Thus, in contrast to previous suggestions, migration to the growth temperature in relation to food is obscure while avoidance of a warm temperature is clearly observed. The results favor a model of C. elegans thermal response that postulates a single drive based on warm sensation rather than one postulating downward and upward drives. Mutants in ttx-3, tax-2, tax-4 or egl-4 genes show abnormal thermal responses, suggesting that these genes are involved in warm avoidance. Laser ablation and gene expression studies suggest that AFD neurons are not important, and tax-4 expression in neurons other than AFD is required, for warm avoidance. Less
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Research Products
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