華中農(nóng)業(yè)大學(xué)在魚類溫度型性別分化領(lǐng)域取得進(jìn)展

　　近日，華中農(nóng)業(yè)大學(xué)魚類遺傳育種與繁育實(shí)驗(yàn)室沈志剛副教授團(tuán)隊(duì)研究成果以“High-temperature stress will put the thermo-sensitive teleost yellow catfish （Tachysurus fulvidraco） in danger through reducing reproductivity”為題在Ecotoxicology and Environmental Safety發(fā)表。研究以黃顙魚為研究對(duì)象，揭示了全球變暖背景下持續(xù)上升的高溫環(huán)境，將通過削弱種群繁殖力，而對(duì)性別分化熱敏魚類的種群維持產(chǎn)生潛在威脅。

 

　　全球溫度升高已成為不爭(zhēng)的事實(shí)，全球表面平均溫度在以每十年提升0.19℃的速度增長(zhǎng)，這可能在未來百年內(nèi)導(dǎo)致數(shù)千種物種滅絕。魚類作為低等脊椎動(dòng)物，物種數(shù)量多，生境分布廣，其性別分化最具多樣性和復(fù)雜性。目前普遍接受的觀點(diǎn)是，雌雄異體魚類的性別是由遺傳（GSD）、環(huán)境（ESD）或兩者的相互作用（GSD+EE）決定的。據(jù)報(bào)道，環(huán)境應(yīng)激包括極端溫度、種群密度、明亮的背景顏色、低溶氧、非中性pH值和食物豐度/質(zhì)量低等所有環(huán)境應(yīng)激源，普遍性地導(dǎo)致魚類雄性化或種群雄性比例增加。因此，全球環(huán)境變暖可能通過改變性別分化方向，打破種群有效性別比例，從而間接推動(dòng)熱敏魚類物種滅絕。團(tuán)隊(duì)前期研究發(fā)現(xiàn)，黃顙魚屬于GSD+EE魚類，高溫能誘導(dǎo)部分XX遺傳型雌性個(gè)體雄性化，是研究環(huán)境與性別分化關(guān)聯(lián)的極好對(duì)象。

 

　　該研究通過三個(gè)方面表明全球變暖（高溫環(huán)境）會(huì)削弱熱敏硬骨魚物種種群持續(xù)性。首先，沈志剛團(tuán)隊(duì)建立了多個(gè)黃顙魚家系，將不同家系幼魚在性別分化溫度敏感時(shí)期暴露于高溫環(huán)境，模擬極端升溫氣候。通過性別特異性分子標(biāo)記與性腺組織學(xué)分析，確定了高溫普遍誘導(dǎo)各家系XX遺傳型雌魚雄性化，但存在明顯的家系差異。其次，通過性腺組織學(xué)和計(jì)算機(jī)輔助精子分析系統(tǒng)，確定了XX偽雄魚繁殖性能顯著低于正常XY雄魚。最后，團(tuán)隊(duì)將XX與XY遺傳型個(gè)體暴露于環(huán)境脅迫中（包括高溫、寄生蟲和低氧脅迫），發(fā)現(xiàn)XY遺傳型在環(huán)境脅迫下表現(xiàn)出更低的存活率。

 

　　此外，該研究還結(jié)合數(shù)學(xué)模型，預(yù)測(cè)了性別分化熱敏魚類在全球變暖大背景下種群性比的變化規(guī)律。

 

　　綜上所述，全球變暖引發(fā)的高溫脅迫將從誘導(dǎo)XX遺傳型雌魚雄性化、削弱XX偽雄魚生殖性能和導(dǎo)致XY遺傳型雄性特異性高死亡率這三方面，使性別分化熱敏性硬骨魚類物種長(zhǎng)期處于潛在的生存威脅之中。

 

　　華中農(nóng)業(yè)大學(xué)碩士研究生于躍為論文的第一作者，沈志剛副教授為論文的通訊作者。本研究得到了中央高?；究蒲袠I(yè)務(wù)費(fèi)專項(xiàng)資金和湖北省自然科學(xué)基金的資助。

 

　　【英文摘要】

 

　　Recently, concerns for species that sex differentiation is influenced by temperature in the context of global warming have increased because disrupted operational sex ratios could threaten population maintenance. In contrast, little attention has been given to the reproductive ability of populations that experienced elevated temperatures. In this study, we demonstrated that high temperature （HT） would decrease population size via three different aspects of reproductive ability for the first time. We show that, in a thermo-sensitive teleost yellow catfish, a short period of HT （+3 ?C） exposure during the critical period of sex differentiation leads to a different percentage of masculinization of XX genotypic females （1–23%） in wet-lab and natural water bodies. Combining the results of gonadal appearance, histology, sperm parameters, and fertilization rate, we found that XX pseudo- males induced by HT display significantly discounted fertility and reproductive performance compared to XY normal males. We demonstrate that the survival of the XY genotype is lower than XX genotype under environmental stress, including HT, hypoxia, and parasite infection, and the differential survival seems unrelated to male-biased sexual size dimorphism. The mathematical model predicts that the phenotypic female percent will be stabilized at 50% and the population will be sustainably maintained when masculinizing force is less than 0.5, while HT will put the population in danger when the masculinizing force exceeds 0.5. However, when we combine the real-world data of reproductive ability and mathematic model, our results suggest the population size decreases and the long-term survival of the studied species are threatened under the projected pace of increasing temperature. These findings will be useful for understanding the long-term effects of increasing temperature on sex ratio, reproduction and population maintenance in teleost.

 

　　論文鏈接：https://www.sciencedirect.com/science/article/pii/S014765132200478X#bib79