横分体形成、ストロビレーション
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出典(authority):フリー百科事典『ウィキペディア(Wikipedia)』「2013/05/05 10:13:51」(JST)
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Strobilation or transverse fission is a form of asexual reproduction consisting of the spontaneous transverse segmentation of the body. It is observed in certain cnidarians and helminths. This mode of reproduction is characterized by high offspring output, which, in the case of the parasitic tapeworms, is of great significance.
Contents
- 1 Strobilation in cnidarians
- 1.1 Examples
- 1.2 Induction in laboratory conditions
- 2 Strobilation in helminths
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Strobilation in cnidarians
- The process starts with preliminary morphological changes. In particular, the cnidarian's tentacles tend to be reabsorbed.
- Neck-formation: transverse constrictions appear near the upper extremity of the animal. A strobilating polyp is called a strobila while the non-strobilating polyp is called a scyphistoma or scyphopolyp.
- Segmentation: the number of constriction sites increases and migrates down the body length, transforming the body into a sequence of disks. The fissures intensify until the initial body is divided into equally spaced, separate segments. The oral end of the polyp becomes the oral end of the ephyra.
- Metamorphosis: The two previous processes involve neurosecretory products, which now disappear.
It is to be noted that neck-formation and segmentation are only separated for clarity purposes. In reality, the two processes are simultaneous, with segmentation to release new ephyras occurring at the upper end while neck formation spreads further down the body. Usually, a portion of the animal remains adhered to the substrate and regenerates the body.
Examples
- The moon jellyfish (Aurelia aurita) reproduces both sexually and by strobilation. This latter process occurs during the colonial polyp stage and produces either polyps or juvenile Medusae called ephyra. Strobilation tend to occur at specific periods, typically early spring. As ephyra size remains constant regardless of the polyp size, larger polyps produce more numerous ephyras.
- Some scyphozoans, such as Nausithoe aurea, cnidarians also strobilate in their solitary polyp form, producing either ephyra or planuloids. Strobilation does not happen periodically, but is thought to be induced by external stimuli, such as iodine, light regime, temperature, or food availability.
Induction in laboratory conditions
Strobilation is successfully induced in laboratory conditions by intensive feeding and temperature lowering, and also by the effect of artificial compounds.
Strobilation in helminths
In cestodes, the whole body except for the head and the neck undergoes strobilation continuously, reflecting the important role reproduction plays in the parasitic mode of life. The strobilating section is called strobila, or scolex, and each of its segment is a proglottid. As they mature, proglottids are disposed of in the feces of the host.
English Journal
- [Research advances in the effects of environmental factors on the growth and development of Aurelia spp].
- Wang JY, Yu ZG, Zhen Y, Mi TZ, Yao QZ, Wang GS.SourceCollege of Marine Life Sciences, Ocean University of China, Qingdao, Shandong, China. wjy198530@163.com
- Ying yong sheng tai xue bao = The journal of applied ecology / Zhongguo sheng tai xue xue hui, Zhongguo ke xue yuan Shenyang ying yong sheng tai yan jiu suo zhu ban.Ying Yong Sheng Tai Xue Bao.2012 Nov;23(11):3207-17.
- Aurelia spp. is a cosmopolitan coastal species, and also, one dominant species of large jellyfish in the coastal waters of China. In recent years, Aurelia spp. bloom events occur frequently in the world, causing severe damage to marine ecosystems, coastal economy, and society development. Aurelia sp
- PMID 23431810
- Jellyfish life histories: role of polyps in forming and maintaining scyphomedusa populations.
- Lucas CH, Graham WM, Widmer C.SourceOcean and Earth Science, National Oceanography Centre Southampton, University of Southampton Waterfront Campus, European Way, Southampton, United Kingdom. cathy.lucas@noc.soton.ac.uk
- Advances in marine biology.Adv Mar Biol.2012;63:133-96. doi: 10.1016/B978-0-12-394282-1.00003-X.
- Large population fluctuations of jellyfish occur over a variety of temporal scales, from weekly to seasonal, inter-annual and even decadal, with some regions of the world reported to be experiencing persistent seasonal bloom events. Recent jellyfish research has focussed on understanding the causes
- PMID 22877612
- Indomethacin induction of metamorphosis from the asexual stage to sexual stage in the moon jellyfish, Aurelia aurita.
- Kuniyoshi H, Okumura I, Kuroda R, Tsujita N, Arakawa K, Shoji J, Saito T, Osada H.SourceFaculty of Applied Biological Science, Graduate School of Biosphere Science, Hiroshima University, Higashi-hiroshima, Hiroshima, Japan. hkuni@hiroshima-u.ac.jp
- Bioscience, biotechnology, and biochemistry.Biosci Biotechnol Biochem.2012;76(7):1397-400. Epub 2012 Jul 7.
- We found while screening a chemical library that indomethacin, an inhibitor of prostaglandin biosynthesis, induced strobilation (metamorphosis from the asexual to sexual stage) in the moon jellyfish, Aurelia aurita. Indomethacin initiated strobilation in a dose-dependent manner, but was not involved
- PMID 22785488
Japanese Journal
- Natural predators of polyps of Aurelia aurita s.l. (Cnidaria: Scyphozoa: Semaeostomeae) and their predation rates
- Takao Mariko,Okawachi Hiroko,Uye Shin-ichi
- Plankton and Benthos Research 9(2), 105-113, 2014
- … Transplanting natural predators to substrates with dense polyp colonies, just prior to their seasonal strobilation, is a possible countermeasure to prevent recurrent medusa blooms. …
- NAID 130004685318
- Indomethacin Induction of Metamorphosis from the Asexual Stage to Sexual Stage in the Moon Jellyfish, Aurelia aurita
- KUNIYOSHI Hisato,OKUMURA Izumi,KURODA Rie,TSUJITA Natsumi,ARAKAWA Kenji,SHOJI Jun,SAITO Tamio,OSADA Hiroyuki
- Bioscience, biotechnology, and biochemistry 76(7), 1397-1400, 2012-07-23
- NAID 10030982335
- Indomethacin Induction of Metamorphosis from the Asexual Stage to Sexual Stage in the Moon Jellyfish, Aurelia aurita
- KUNIYOSHI Hisato,OKUMURA Izumi,KURODA Rie [他],TSUJITA Natsumi,ARAKAWA Kenji,SHOJI Jun,SAITO Tamio,OSADA Hiroyuki
- Bioscience, Biotechnology, and Biochemistry 76(7), 1397-1400, 2012
- … We found while screening a chemical library that indomethacin, an inhibitor of prostaglandin biosynthesis, induced strobilation (metamorphosis from the asexual to sexual stage) in the moon jellyfish, Aurelia aurita. … Indomethacin initiated strobilation in a dose-dependent manner, but was not involved in the progression of strobilation. … Pharmacological experiments suggested that indomethacin could induce strobilation independently of prostaglandin biosynthesis. …
- NAID 130001862721
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- strobilation 【名】《動物》横分体形成 - アルクがお届けする進化するオンライン英和・和英辞書データベース。一般的な単語や連語から、イディオム、専門用語、スラングまで幅広く収録。
- Definition of STROBILATION: asexual reproduction (as in various coelenterates and tapeworms) by transverse division of the body into segments which develop into separate individuals, zooids, or proglottids ADVERTISEMENT Origin ...
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