Male silver eels mature by swimming
BMC Physiology
2008, 8:14 doi:10.1186/1472-6793-8-14
Abstract
Background
If European silver eels are prevented from
reproductive migration, they remain in a prepubertal stage by dopaminergic
inhibition of pituitary activity. Because this inhibition is likely a
requirement for an extended female growth stage, we tested if it is sex-specific
by subjecting both sexes to stimulation by GnRHa (Gonadotropin-Releasing Hormone
agonist) – injection or 3-months swimming in seawater.
Results
In contrast to females, males showed a two- to
three-fold higher LHβ (luteinising hormone β subunit) – expression, a three- to
five-fold higher GSI (Gonadosomatic index) and induced spermatogenesis when
compared with the untreated control group.
Conclusion
Dopaminergic inhibition is thus not effective in
males and swimming results in natural maturation, probably via GnRH-release.
歐洲鰻（Anguilla anguilla）可遷移6000公里至位於馬尾藻海的產卵區。最近發現，雄性游泳比雌性更有效率，預測雄性也可以在六個月內游泳〜6000公里。此外，鰻魚不能自然的性成熟，是歸咎由於強烈的神經性抑制。之前，有人推測游泳可自然觸發誘導雄鰻性成熟，甚至有可使雄鰻完全成熟。在本研究中，養殖的雄銀鰻分兩組: 耐力游泳與休息長達6個月。發現，6個月內雄性鰻魚能夠連續遊的6670公里。6個月後，游泳和休息的雄鰻體重下降相似（<30克），顯示游泳的極端能耗低。但長期游泳也不會導致養殖雄鰻魚銀的性成熟，這表明，作為性成熟的觸發器，單純游泳是不夠的，。總之，雄性的鰻魚是有效的長距離游泳和可能能夠覆蓋6個月的預期時間跨度內的馬尾藻海的距離。
Comp Biochem Physiol A Mol Integr Physiol. 2013 Nov;166(3):522-7. doi: 10.1016/j.cbpa.2013.08.002. Epub 2013 Aug 17.
Male European eels are highly efficient long distance swimmers: effects of endurance swimming on maturation.
Abstract
European eels (Anguilla anguilla) migrate ~6000km towards their spawning area in the Sargasso Sea. Based on the recent discovery that males swim even more efficiently than females, it was predicted that males also would be able to swim ~6000km within six months. Additionally, eels do not mature naturally in captivity due to strong neural inhibition. Earlier, it was hypothesized that swimming exercise is a natural trigger to induce sexual maturation and may even result in full maturation. In the present study two groups of farmed male silver eels were subjected to either endurance swimming or resting for up to 6months. It was found that male eels were able to swim continuously for a total distance of 6670km within 6months. The body weight decrease in swimming and resting males after 6months was similar (<30g 6months.="" a="" able="" alone="" and="" are="" as="" conclusion="" contrast="" cost="" cover="" did="" distance="" eels="" efficient="" energy="" expectation="" expected="" extreme="" farmed="" for="" in="" induce="" is="" likely="" long-term="" long="" low="" male="" maturation.="" maturation="" not="" of="" our="" p="" sargasso="" sea="" sexual="" silver="" span="" sufficient="" suggesting="" swimmers="" swimming.="" swimming="" that="" the="" time="" to="" trigger="" underlining="" within="">© 2013.
No comments:
Post a Comment