生命是短暫的,，特別對(duì)那些成熟快,、死亡早的動(dòng)物來(lái)說(shuō),，更是如此。所以,，沒(méi)有理由不抓緊時(shí)間生活每一天,。美國(guó)科學(xué)家近日研究發(fā)現(xiàn)，生活速度快（壽命較短）的小鼠更愿意用發(fā)燒而不是發(fā)育完全的免疫響應(yīng)來(lái)應(yīng)對(duì)受到的感染,，這樣它們就不必打斷日常生活以從疾病中康復(fù),。相關(guān)論文10月29日在線發(fā)表于《功能生態(tài)學(xué)》（Functional Ecology）上。
動(dòng)物對(duì)付病菌的方法除了使用免疫系統(tǒng)外，還有其它多種方法,，比如提高身體溫度,、減少進(jìn)食、嗜睡,、減少性活動(dòng)和進(jìn)攻行為等,。但是這些方法都會(huì)帶來(lái)副作用，比如減少性活動(dòng)會(huì)損害健康,，而身體溫度每提高1攝氏度就要消耗身體多于10%的能量,。而關(guān)于不同動(dòng)物不同選擇的內(nèi)在原因，科學(xué)家所知甚少,。
在最新的研究中,，美國(guó)南佛羅里達(dá)大學(xué)的進(jìn)化生態(tài)學(xué)家Lynn Martin和同事向美國(guó)、加拿大和墨西哥的5種親緣關(guān)系很近的小鼠注射了脂多糖（lipopolysaccharide）,，使小鼠身體產(chǎn)生感染癥狀,。研究人員隨后監(jiān)測(cè)了這些小鼠24小時(shí)之內(nèi)的身體溫度和行為模式。
結(jié)果發(fā)現(xiàn),，快速生活的白足鼠（Peromyscus leucopus）和鹿鼠（P. maniculatus）很快就產(chǎn)生了發(fā)燒癥狀,；較慢速生活的阿茲臺(tái)克鼠（P. Aztec）和高原鼠（P. melanophrys）只有一點(diǎn)點(diǎn)發(fā)燒癥狀或者完全沒(méi)有；而生活節(jié)奏更慢的荒漠鼠（P. californicus）體溫不僅沒(méi)有提高,，反而有所下降,。
Martin認(rèn)為，這其中的原因在于,，發(fā)燒能夠幫助清除病原體,，效果較快,。但是發(fā)燒同樣會(huì)對(duì)身體組織造成長(zhǎng)期的損害,，這會(huì)縮短壽命。對(duì)于壽命較短的動(dòng)物來(lái)說(shuō),，發(fā)燒是更好的選擇,，因?yàn)槿绻麎勖嵌虝旱模敲淳筒粫?huì)在乎長(zhǎng)期的損害,，也不會(huì)愿意花上3到4周的時(shí)間來(lái)從疾病中康復(fù),。而對(duì)于壽命較長(zhǎng)的動(dòng)物來(lái)說(shuō)，它們更愿意依賴效果慢但副作用也小的抗體來(lái)對(duì)付感染,。這很好地解釋了,，為什么慢速生活的小鼠在實(shí)驗(yàn)中表現(xiàn)出疾病行為，而快速生活的小鼠很少表現(xiàn)或不表現(xiàn),。
美國(guó)加州大學(xué)戴維斯分校的動(dòng)物學(xué)家Kirk Klasing說(shuō),，之前有許多科學(xué)家猜測(cè)，動(dòng)物不同的生活策略會(huì)導(dǎo)致選擇不同的方式來(lái)抵御病原體,，而這次的研究第一次給出了明確的證據(jù),。（科學(xué)網(wǎng) 杰克·梅/編譯）
原始出處:
OnlineEarly Articles
To cite this article: Lynn B. Martin II, Zachary M. Weil, Randy J. Nelson
Fever and sickness behaviour vary among congeneric rodents
Functional Ecology (OnlineEarly Articles).
doi:10.1111/j.1365-2435.2007.01347.x
Fever and sickness behaviour vary among congeneric rodents
Lynn B. Martin II**Correspondence author. Division of Integrative Biology, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620, USA. E-mail: [email protected], Zachary M. Weil and Randy J. Nelson
Departments of Psychology, Neuroscience, and Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, OH 43210, USA
*Correspondence author. Division of Integrative Biology, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620, USA. E-mail: [email protected]
Key-words : acute phase response, immune, lipopolysaccharide, Peromyscus, trade-off
Functional Ecology (2007) doi: 10.1111/j.1365-2435.2007.01347.x
Functional Ecology (2007) xx, 000–000
1. Fever and sickness behaviour are immune defences that most organisms engage to control bacterial and viral infections. Although generally beneficial, these defences can be energetically expensive, which may lead to variation within and among species. Here, we asked whether fever and sickness behaviour differ among five species of mice in the genus, Peromyscus.
2. This comparison was motivated by our previous discovery of extensive, but systematic, immunological variation among many of these same rodent species. Some species were adept at controlling gram-negative bacteria whereas others were proficient at generating antibodies; no species was strongly capable of both. Such discrete variation suggested a continuum of immune defence strategies. We therefore predicted that variation in fever and sickness behaviour would mirror variation in bacterial killing capacity, as these defences are mediated by some of the same molecular pathways.
3. To test this hypothesis, we characterized responses to lipopolysaccharide (LPS), a component of gram-negative bacteria that activates febrile responses without causing infection. Peromyscus species that showed little sickness behaviour post-LPS engaged fever; species that engaged sickness behaviour, however, either did not mount fevers or became hypothermic post-LPS. As predicted, species that were adept at killing bacteria in vitro mounted the largest fevers; species that were not as proficient at killing bacteria did not engage fever.
4. These results further indicate a continuum of immunological strategies among Peromyscus species, which we expect applies to other taxa. We propose a few possible reasons for why species occupy specific points along an immune continuum; life-history orientation appears the most viable alternative at present.
