Recent origin of a hominoid-specific splice form of neuropsin, a gene involved in learning and memory

Neuropsin is a secreted-type serine protease involved in learning and memory. The type II splice form of neuropsin is abundantly expressed in the human brain but not in the mouse brain. We sequenced the type II-spliced region of neuropsin gene in humans and representative nonhuman primate species. Our comparative sequence analysis showed that only the hominoid species (humans and apes) have the intact open reading frame of the type II splice form, indicating that the type II neuropsin originated recently in the primate lineage about 18 MYA. Expression analysis using RT-PCR detected abundant expression of the type II form in the frontal lobe of the adult human brain, but no expression was detected in the brains of lesser apes and Old World monkeys, indicating that the type II form of neuropsin only became functional in recent time, and it might contribute to the progressive change of cognitive abilities during primate evolution.

Origin and evolution of ubiquitin-conjugating enzymes from Guillardia theta nucleomorph to hominoid

The origin of eukaryotic ubiquitin-conjugating enzymes (E2s) can be traced back to the Guillardia theta nucleomorph about 2500 million years ago (Mya). E2s are largely vertically inherited over eukaryotic evolution [Lespinet, O., Wolf, Y.I., Koonin, E.V.,

灵长类大脑表达若干基因的分子进化研究

一百多年前，Huxley和Darwin提出人和非洲大猿的亲缘关系最近。虽然精确的成种时间还不能确定，不过目前已被广泛接受的是：人与黑猩猩的分歧时间是．5-6百万年前。相对几十亿年的生命进化历史而言，5-6百万年可以说是短暂的，但在系统发育树上的人猿超科（Hominoid）这支却由于大脑容量急剧扩张，复杂性迅速提高，导致他们的行为更加丰富，有了语言，工具和学习的本领，从而在生物界占据了统治地位。究竟是什么让我们在遗传水平上区别于其他灵长类，特别是我们的近亲－－一大猿？这个生物学问题不仅和人类的生命，道德，哲学观密不可分，而且也是困挠人类多年并仍是遗传学家和进化学家关心的问题。通过比较人和近缘物种黑猩猩的基因组序列，我们发现他们之间存在很强的序列相似性，达到近99％（在编码区）。因此我们推测，灵长类之间的功能差异尤其是认知功能的差异可能来自两个方面：1）脑部发育控制基因的序列差异；2）基因的差异表达，特别是脑部的基因。遗传差异存在于不同水平，如细胞结构总体改变、局部染色体重排、基因家族重复、单基因修饰（包括新基因的产生）、差异表达基因和RNA可变剪接等。人类基因有超过55％都存在可变剪接，它是蛋白质多样性的重要来源。相比较其他组织、器官而言，脑部拥有可变剪接形式的基因的数量是最多的。因此，我们利用高灵敏的PolonyexonProfiling技术寻找人和非人灵长类间可变剪接的差异，试图发现人特异的剪接异构体，了解可变剪接对人的认知功能的影响。另一方面，我们试图通过比较人和非人灵长类基因序列的差异，找到那些在人起源过程中受到强烈正选择的基因。我们从约51个有明显正选择迹象的基因中选取一个基因－－－一CXCRI，测定了全世界范围内的人群以及非人灵长类中的代表物种，结果显示CXCRI的配体受体结合位点处的序列在人这一支受到了强烈的适应选择作用，这一适应很有可能和人类起源过程中免疫系统的适应有关。

元谋地区晚新生代河湖相沉积物磁性地层学及古环境研究

Yuanmou area lies on the southeastern edge of the Tibetan Plateau, the middlesegment of Yunnan-Sichuan North-South Extending Tectonic Belt and the upper reaches of the Yangztze River, which is renowned for its thick late Cenozoic fluvial-lacustrine sequences that yield rich mammalian fossils including hominoid and early human. The sediments provides great potentials for understanding the relationships between uplift of the Tibetan Plateau, evolution of hominoids and other mammalian and evolution and formation of basins in Southwest China since late Miocene. However, lithostratigrphic and chronologic views on them are controversial and hinder further discussion of the relationships of them. To this end, we selected the Baozidongqing section and the Dapoqing section to carry out systematic lithostratigraphic, magnetostratlgraphic and environmental magnetism researches in this area.The Baozidongqing section was dated to about 10.95-7.17 Ma. The age estimation of the topmost hominoid-bearing layer was about 7.43-7.17 Ma. Rock magnetic results show that the dominant magnetic carrier is hematite, with minor amount of magnetite. Both the composition and concentration of magnetic minerals strongly correlate with the lithostratigraphy, indicating that Yuanmou basin is characterized by alternating of long-term torrid-humid climate and short-term dry-hot climate. But the pattern of these short-term hot-dry events, including both the lasting time and the frequency of their occurrence dramatically changed since -8.1 Ma. Our results infer that the drying process of the Asian west interior and a significant uplift of the Tibetan Plateau would have probably caused jointly the extinction of hominoids, or the emigration of hominoids from Yuanmou to adjacent relatively torrid-humid areas.The strata between the upper of the Dapoqing section, the Niujianbao Hill and Shangnabang area can be linked by three mark layers of conglomerate, which is rather continuous and coherent than physical disturbance by new tectonic activities. Rock magnetic studies indicate that hematite is the main magnetic carriers. The section is dated back to about 2.8-1.37 Ma. Its paleocurrent flowed northeastward, which was a close and stagnant river and swamp environment about 2.2 Ma ago. Then it ran northwestward and turned into an open overflown and braid river sedimentary face during 2.2 to 1.57 Ma. Since 1.57 Ma, the paleocurrent flowed intensely northwestern and about 1.37 Ma ago, it ended the basically continuous fluvial-lacustrine deposition.