本期Scientific Reports上發(fā)表的一篇文章提出,，不同種類的鯨利用不同機(jī)制來抵抗紫外線(UV)輻射的有害影響。還需要進(jìn)一步的研究來弄清UV輻射對(duì)鯨的長(zhǎng)期影響,。
以前的研究表明,，紫外線能對(duì)鯨造成皮膚損傷,。Mark Birch-Machin、Karina Acevedo-Whitehouse及其同事在基因?qū)用嫔涎芯苛薝V輻射對(duì)鯨的影響,，并將損傷與鯨的遷徙模式聯(lián)系了起來,。該小組測(cè)定了來自藍(lán)鯨、長(zhǎng)須鯨和抹香鯨的皮膚樣品中的線粒體DNA(mtDNA)水平,，將其作為DNA損傷的一個(gè)標(biāo)記,。
作者發(fā)現(xiàn)，較高的黑色素水平傾向于與較低的微損傷和mtDNA損傷水平相關(guān)聯(lián),，這說明黑色素可能對(duì)太陽輻射有保護(hù)作用,。他們發(fā)現(xiàn)，藍(lán)鯨可以響應(yīng)于紫外線而改變它們皮膚的色素沉積,。這種響應(yīng)于UV輻射而改變黑色素水平（來使皮膚變成象征健康的棕色）的能力可能與藍(lán)鯨的遷徙模式有關(guān),，因?yàn)樗鼈兠磕暌獜妮^高緯度地區(qū)遷徙到較低緯度地區(qū)，進(jìn)入到紫外線水平較高的環(huán)境中,。長(zhǎng)須鯨永久性地在一個(gè)紫外線水平高的區(qū)域生活,，它們改變皮膚色素沉積的能力降低，其皮膚中的黑色素水平始終保持較高,。在所研究過的鯨類中,，對(duì)長(zhǎng)須鯨所記錄到的曬傷發(fā)生數(shù)量最低。
抹香鯨（它們?cè)诤Ｑ蟊砻嫔弦淮慰梢源糸L(zhǎng)達(dá)六小時(shí)）的反應(yīng)方式不同,，它們會(huì)響應(yīng)于紫外線輻射激活基因毒性應(yīng)激通道,。較高水平的HSP70（作為這一反應(yīng)一部分而表達(dá)的蛋白之一）被發(fā)現(xiàn)與抹香鯨較低的mtDNA損傷發(fā)生率相關(guān)聯(lián)，說明這些通道也許能防護(hù)紫外線損傷,。（生物谷 Bioon.com）
生物谷推薦的英文摘要
Scientific Reports doi:10.1038/srep02386
Whales Use Distinct Strategies to Counteract Solar Ultraviolet Radiation
Laura M. Martinez-Levasseur,1, 2, 7 Mark A. Birch-Machin,3 Amy Bowman,3 Diane Gendron,4 Elizabeth Weatherhead,5 Robert J. Knell2 & Karina Acevedo-Whitehouse1, 6
A current threat to the marine ecosystem is the high level of solar ultraviolet radiation (UV). Large whales have recently been shown to suffer sun-induced skin damage from continuous UV exposure. Genotoxic consequences of such exposure remain unknown for these long-lived marine species, as does their capacity to counteract UV-induced insults. We show that UV exposure induces mitochondrial DNA damage in the skin of seasonally sympatric fin, sperm, and blue whales and that this damage accumulates with age. However, counteractive molecular mechanisms are markedly different between species. For example, sperm whales, a species that remains for long periods at the sea surface, activate genotoxic stress pathways in response to UV exposure whereas the paler blue whale relies on increased pigmentation as the season progresses. Our study also shows that whales can modulate their responses to fluctuating levels of UV, and that different evolutionary constraints may have shaped their response strategies.
