In this paper, two studies on primates were conducted. Firstly, a bacterial artificial chromosome (BAC) library was constructed, which provided a valuable resource for primate genomic study. Secondly, the molecular evolution of neurotrypsin gene was dissected, which provided insight into the development of high-order cognition function in primates at molecular level. he Yunnan snub-nosed monkey (Rhinopithecus bieti), one of the rarest and most endangered primates in the world, is indigenous to china. Based on morphological study, it occupies an intermediate position between the Old World monkeys and the lesser apes, therefore, a keystone species in understanding primate evolution. We constructed a high redundancy bacterial artificial chromosome library of a seriously endangered Old World Monkey, the Yunnan snub-nosed monkey (Rhinopithecus bieti) from China. This library contains a total of 136,320 BAC clones. The average insert size of BAC clones was estimated to be 148 kb. The percentage of small inserts (50-100- kb) is 2. 74%, and only 2. 67% non-recombinant clones were observed. Assuming-a similar genome size with closely related primate species, the Yunnan snub-nosed monkey BAC library has at least six times genome-coverage. By end sequencing of randomly selected BAC clones, we generated 201 sequence tags for the library. A total of 139 end-sequenced BAG clones were mapped onto the chromosomes of Yunnan snub-nosed monkey by fluorescent in-situ hybridization, demonstrating a high degree of synteny conservation between humans and Yunnan snub-nosed monkeys. Blast search against human genome showed a good correlation between the number of hit clones and the size of the chromosomes, an indication of unbiased chromosomal distribution of the BAG library. This library and the mapped BAG clones will serve as a valuable resource in comparative genoinics study and large-scale genome sequencing of onhuman primates. eurotrypsin is one of the extra-cellular serine proteases that are predominantly expressed in the brain and involved in neuronal development and function. Its mutations in humans are associated with autosomal recessive non-syndromic mental retardation (MR). We studied the molecular evolution of neurotrypsin by sequencing the coding region of neurotrypsin in 11 representative non-human primate species covering great apes, lesser apes, Old World monkeys and New World monkeys. Our results demonstrated a strong functional constraint of neurotrypsin which was caused by strong purifying selection during primate evolution, an implication of an essential functional role of neurotrypsin in primate cognition. Further analysis indicated that the purifying selection was in fact acting on the SRCR domains of neurotrypsin, which mediate the binding activity of neurotrypsin to cell surface or extra-cellular proteins. In addition, by comparing primates with three other mammalian orders, we demonstrated that the absence of the first copy of the SRCR domain (exon 2 and 3) in mouse and rat was due to the deletion of this segment in the murine lineage.
修改评论