2001 Fiscal Year Final Research Report Summary
EVOLUTIONARY STUDY OF ENVIRONMENT-DEPENDENT MUTATIONS OF TRIMERESURUS FLAVOVIRIDIS VENOM-GLAND PHOSPHOLIPASE A2 ISOZYME GENES
| Project/Area Number |
12640689
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
系統・分類
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| Research Institution | SOJO UNIVERSITY |
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Principal Investigator |
OHNO Ryuichi SOJO UNIV., DEPT. APPLIED LIFE SCI.,PROF., 工学部, 教授 (30038434)
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| Co-Investigator(Kenkyū-buntansha) |
HATTORI Shosaku TOKYO UNIV., INST. MED. SCI., ASSOC. PROF, 医科学研究所, 助教授 (00164864)
UEDA Naoko SOJO UNIV., DEPT. APPLIED LIFE SCI., ASSOC. PROF, 工学部, 助教授 (70211828)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Southwestem islands of Japan / Trimeresurus flavoviridis / Isolated environments / Venom-gland phospholipase A2 isozymes / Gene mutation / Pseudogene / Feeding habit / Adaptive evolution |
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| Research Abstract |
Trimeresurus flavoviridis (Tf) snakes inhabit the southwestern islands of Japan : Amami-Oshima, Tokunoshima and Okinawa. These islands are thought to have been separated one to two million years ago by eustacy (changes in sea level) in the erogenic stage. This work is to correlate mutations of Tf venom-gland phospholipase A_2 (PLA_2) isozyme genes with their isolated environments. When the venoms of Amami-Oshima, Tokunoshima and Okinawa Tf snakes were chromatographed, two [Lys^<49>]PLA_2s called BPI and BPII are missing only in Okinawa Tf venom. Northern blot analysis showed the absence of BPI and BPII mRNAs in Okinawa Tf venom gland. Amplification by polymerase chain reaction (PCR) of the segments of BPI and BPII genes with specific primers against Okinawa Tf genomic DNA together with PCR amplification of the segments including polymorphic positions in the upstream and downstream regions of BPI and BPII genes and analysis of their sequences established that the upstream region of BPI
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gene and the downstream region of BPII gene are fused to form pseudogene in Okinawa Tfgenome. Since BPI and BPII have strong necrotic activity, it is thought that the lack of BPI and BPII is of great disadvantage to Okinawa Tf. However, they seem to subsist well. In Yambaru, a mountain area covered with forests in the northern part of Okinawa, Tf snakes mostly (90%) prey on Hoist's frogs (Rana holsti) inhabiting the streams in this area. This natural, wild area seems to reflect the environment in Okinawa in which Tfsnakes lived in ancient times. It could be assumed that these feeding habits over a long period affected the venom components in Okinawa Tf and the lack of necessity for a strong venom toxicity gave rise to inactivation of BPI and BPII genes in an adaptive manner. PLA-B from Tokunoshima Tf venom can produce edema. However, PL-Y in Okinawa Tf venom which has only three substituted residues, is inactive for edema. Such mutation is also dependent on the difference in their living environments. Less
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Research Products
(12 results)
