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翼手目回声定位相关功能基因的进化以及若干蝙蝠生殖研究

Study on the Evolution of Genes Related to Echolocation of Bats and Reproductive Strategy Analysis of Some Bats in China

【作者】 钟辉

【导师】 刘湘新; 张树义;

【作者基本信息】 湖南农业大学 , 基础兽医学, 2008, 硕士

【摘要】 一、翼手目(Chiroptera)是哺乳动物纲的第二大目,其种类和数量仅次于啮齿目。俗称蝙蝠,是惟一真正会飞翔的哺乳动物类群。分布几乎遍及两极以外的世界各地,而以热带地区最为丰富。翼手目可能和灵长目共同起源于类似食虫目的最原始的真兽类,现生翼手目分为大蝙蝠亚目和小蝙蝠亚。前者仅包括狐蝠科一个科,41属188种,不分亚科;分布于旧大陆热带、亚热带地区;后者种类繁多,包括17科160属919种,另有17个亚科,其分类系统如下:菊头蝠科1属76种;蹄蝠科9属80种;假吸血蝠科4属5种;鼠尾蝠科1属4种;凹脸蝠科1属1种;鞘尾蝠科包含2个亚科,13属51种;夜凹脸蝠科1属16种;吸足蝠科1属1种;短尾蝠科1属2种;兔唇蝠科1属2种;髯蝠科2属10种:叶口蝠科包含7个亚科,55属158种;烟蝠科2属2种;盘翼蝠科)1属3种;长腿蝠科3属6种;犬吻蝠科包含2个亚科,16属100种;蝙蝠科包含6个亚科,48属402种,分布范围广泛。二、精子储存是蝙蝠的生殖对策之一,有些种类的蝙蝠能将成熟精子在交配前(雄性)或交配后(雌性)储存在附睾或者输卵管及子宫内数月。我们采用冰冻切片和苏木精-伊红(H.E)染色法,观察了中国六种蝙蝠的睾丸、附睾、卵巢、输卵管和子宫等组织器官,发现其中5种蝙蝠有精子储存现象。同时,我们还讨论了不同生殖对策蝙蝠的地理分布情况。三、Foxp2基因是一个转录因子,很多研究结果表明该基因在口面部的协调运动的发育和调节方面扮演着重要的角色,尤其是对生物体在发声机制上有着不可或缺的关键作用。在进一步的对灵长类的Foxp2基因的研究中发现,尽管这个基因在高等灵长类中几乎没有变化,但是在人类祖先同黑猩猩在大约在1000万年前分离后,Foxp2基因在人类种群中只出现了两个氨基酸突变,而且对不同人种的研究显示这两个氨基酸突变稳定的固定在不同人类种群中。这个Foxp2基因在人类中的显著的进化加速被认为同人类语言能力的产生有密切的联系。同样,在蝙蝠类群中,因为回声定位这一特殊机制的客观要求,蝙蝠具有极高水平的感觉运动能力。为了研究Foxp2基因同蝙蝠回声定位能力之间的潜在联系,我们扩增并测序了10科43种不同蝙蝠物种和27种不同目的非翼手目哺乳动物代表物种、一种爬行类代表物种的全长或部分Foxp2基因,还从基因组文库中获得了已经测序的哺乳动物Foxp2基因的全长序列,并结合已发表的灵长类、小鼠、两种鸟类的Foxp2基因进行联合分析。我们研究结果显示,在哺乳动物中,Foxp2基因高度保守,但是在具有回声定位能力的不同蝙蝠物种中,Foxp2基因具有显著的多态性。利用最大似然法进行的Foxp2基因的进化研究指出,这一结果是由具有显著性的自然选择促使了Foxp2基因在翼手目中分化。我们的研究结果说明Foxp2基因调控功能对蝙蝠的回声定位能力的发展、进化都起到了相关的作用。同时,我们对翼手目和其他哺乳动物类群的Foxp2基因的比较进化研究也进一证明了Foxp2基因的功能同感觉运动的协调性这两者之间的不可分割的联系。

【Abstract】 1. Chiroptera is the second order in mammal class, its category and amount second only Rodentia. Commonly called bats, is really only mammal group to be hover. They are distributed the globe besides two poles,there are plentiful of it in torrid zone. Maybe Chiroptera and Primates are co-genesia the most primal genuine beasts what to be similar Insectivora, now Chiroptera divide into Megachiroptera and Microchiroptera. The former merely consist of Pteropodidae,41 genus 188 species,no subfamily,distributed by archcontinent tropics and subtropical zone;The latter have a kind of species,include 17 department 160 genus 919 species,and 17 subfamily,its classification system as follow: Rhinolophus,1 genus 76 species; Vespertilionidae,48genus 402 species,and 6 subfamily. Megadermatidae 4 genus 5 species;Rhinopomatidae 1 genus 4 species;Craseonycteridae 1 genus 1 species; Emballonuridae 13 genus 51 species and 2 subfamily; Nycteridae 1 genus 16 species;Mystacinidae 1 genus 2 species;Myzopodidae , 1 genus 1 species;Noctilionidae ,1 genus 2 species; Mormoopidae ,2 genus 10 species; Phyllostomidae ,55 genus 158 species,and 7 subfamily; Furipteridae 2 genus 2 species;Thyropteridae,l genus 3 species;Natalidae ,3 genus 6 species;Molossidae ,4 genus 5 species; Hipposideridae ,9 genus 80 species;its distribution range is widespread.2. Sperm storage is a reproductive strategy of bats. Some species of bats can store mature spermatozoa in epididymis (male) or oviducts and uterus (female) for months. We observed testes, epididymis, ovaries, oviducts and uteri for six species of microbats by the method of Haematoxylin and Eosin (H.E) staining for frozen tissue sections and found sperm storage in five of them. In addition, we discussed the distribution of bats with different reproductive strategies.3. Foxp2 is a transcription factor implicated in the development and neural control of orofacial coordination, particularly with respect to vocalisation. Observations that orthologues show almost no variation across vertebrates yet differ by two amino acids between humans and chimpanzees have led to speculation that recent evolutionary changes might relate to the emergence of language. Echolocating bats face especially challenging sensorimotor demands, using vocal signals for orientation and prey capture. To determine whether mutations in the Foxp2 gene could be associated with echolocation, we sequenced Foxp2 from 43 echolocating and non-echolocating bats as well as 27 other mammal species. With the sequences obtained form the BAC libraries and the published Foxp2 suquences from GenBnank, we analyses the data using the maximum likelihood method. We found that contrary to previous reports, Foxp2 is not highly conserved across all nonhuman mammals but is in fact extremely diverse in echolocating bats. We detected divergent selection at Foxp2 between bats with contrasting sonar systems, suggesting the intriguing possibility of a role in the evolution and development of echolocation. We speculate that observed accelerated evolution of Foxp2 in bats supports a previously proposed function in sensorimotor coordination.

【关键词】 精子储存Foxp2基因回声定位蝙蝠进化
【Key words】 Sperm storageFoxp2 geneEcholocateBatEvolution
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