Tracing the Origins of Hakka and Chaoshanese by Mitochondrial DNA Analysis

Hakka and Chaoshanese are two unique Han populations residing in southern China but with northern Han (NH) cultural traditions and linguistic influences. Although most of historical records indicate that both populations migrated from northern China in the last two thousand years, no consensus on their origins has been reached so far. To shed more light on the origins of Hakka and Chaoshanese, mitochondrial DNAs (mtDNAs) of 170 Hakka from Meizhou and 102 Chaoshanese from Chaoshan area, Guangdong Province, were analyzed. Our results show that some southern Chinese predominant haplogroups, e.g. B, F, and M7, have relatively high frequencies in both populations. Although median network analyses show that Hakka/Chaoshanese share some haplotypes with NH, interpopulation comparison reveals that both populations show closer affinity with southern Han (SH) populations than with NH. In consideration of previous results from nuclear gene (including Y chromosome) research, it is likely that matrilineal landscapes of both Hakka and Chaoshanese have largely been shaped by the local people during their migration southward and/or later colonization in southern China, and factors such as cultural assimilation, patrilocality, and even sex-bias in the immigrants might have played important roles during the process. Am J Phys Anthropol 141:124-130, 2010. (C) 2009 Wiley-Liss, Inc.

Stepwise loss of motilin and its specific receptor genes in rodents

Specific interactions among biomolecules drive virtually all cellular functions and underlie phenotypic complexity and diversity. Biomolecules are not isolated particles, but are elements of integrated interaction networks, and play their roles through specific interactions. Simultaneous emergence or loss of multiple interacting partners is unlikely. If one of the interacting partners is lost, then what are the evolutionary consequences for the retained partner? Taking advantages of the availability of the large number of mammalian genome sequences and knowledge of phylogenetic relationships of the species, we examined the evolutionary fate of the motilin (MLN) hormone gene, after the pseudogenization of its specific receptor, MLN receptor (MLNR), on the rodent lineage. We speculate that the MLNR gene became a pseudogene before the divergence of the squirrel and other rodents about 75 mya. The evolutionary consequences for the MLN gene were diverse. While an intact open reading frame for the MLN gene, which appears functional, was preserved in the kangaroo rat, the MLN gene became inactivated independently on the lineages leading to the guinea pig and the common ancestor of the mouse and rat. Gain and loss of specific interactions among biomolecules through the birth and death of genes for biomolecules point to a general evolutionary dynamic: gene birth and death are widespread phenomena in genome evolution, at the genetic level; thus, once mutations arise, a stepwise process of elaboration and optimization ensues, which gradually integrates and orders mutations into a coherent pattern.

Molecular characterization of six Chinese families with m.3460G > A and Leber hereditary optic neuropathy

The primary mutation m.3460G > A occurs with a very low frequency (similar to 1%) in Chinese patients with Leber hereditary optic neuropathy (LHON). Up to now, there is no comprehensive study of Chinese patients harboring this mutation. We characterized six unrelated probands with m.3460G > A in this study, which were identified from 1,626 patients with LHON or suspected with LHON. The overall penetrance of LHON (25.6% [10/39]) in four pedigrees with m.3460G > A was substantially lower than those families with m.11778G > A (33.3% [619/1859]) as reported in our previous study. Intriguingly, family Le688 with a heteroplasmic m.3460G > A presented a lower penetrance (12.5%) than the other three families with a homoplasmic mutation. There is an elevated gender bias (affected male to affected female = 4:1) in the four families with m.3460G > A compared to those LHON families with m.11778G > A (2.4:1). Complete mtDNA sequencing indicated that the six matrilines belonged to haplogroups B4d1, F2, A5b, M12a, D4b2b, and D4b2, respectively. We did not identify any potential secondary mutation(s) that will affect or be associated with the penetrance of LHON in the six probands by using an evolutionary analysis and protein secondary-structure prediction. Taken together, our results suggested that the m.3460G > A mutation occurred multiple times in Chinese LHON patients. The heteroplasmic status of mutation m.3460G > A might influence the penetrance of LHON in family Le688.

The Acquisition of an Inheritable 50-bp Deletion in the Human mtDNA Control Region Does Not Affect the mtDNA Copy Number in Peripheral Blood Cells

The mitochondrial DNA (mtDNA) control region is believed to play an important biological role in mtDNA replication. Large deletions in this region are rarely found, but when they do occur they might be expected to interfere with the replication of the molecule, thus leading to a reduction of mtDNA copy number. During a survey for mtDNA sequence variations in 5,559 individuals from the general Chinese population and 2,538 individuals with medical disorders, we identified a 50-bp deletion (m.298_347del50) in the mtDNA control region in a member of a healthy Han Chinese family belonging to haplogroup B4c1b2, as suggested by complete mtDNA genome sequencing. This deletion removes the conserved sequence block II (CSBII; region 299-315) and the replication primer location (region 317-321). However, quantification of the mtDNA copy number in this subject showed a value within a range that was observed in 20 healthy subjects without the deletion. The deletion was detected in the hair samples of the maternal relatives of the subject and exhibited variable heteroplasmy. Our current observation, together with a recent report for a benign 154-bp deletion in the mtDNA control region, suggests that the control of mtDNA replication may be more complex than we had thought. Hum Mutat 31:538-543, 2010. (C) 2010 Wiley-Liss, Inc.

Anti-HIV-1 Activities of Hemslecins A and B

目的:研究从药用植物金佛山雪胆分离的雪胆素A和雪胆素B两个三萜类化合物的体外抗HIV活性.方法:应用合胞体抑制实验、p24抗原产生的抑制实验、慢性感染细胞和正常细胞间的细胞融合抑制实验等技术检测化合物的体外抗HIV-l活性;利用HIV-l逆转录酶、蛋白酶抑制实验,NCp7锌离子逐出实验探讨化合物的作用机制.结果:雪胆素A和雪胆素B在体外有较好的抑制HIV-l活性,其活性主要表现为:(1)抑制HIV-l诱导合胞体形成,EC50值分别为3.09 μg·mL-1和2.53μg·mL-1;(2)抑制HIV- 急性感染的C8106细胞p24抗原产生,EC50值分别为3.97μg·mL-1和18.90μg·mL-1;(3)抑制HIV-1 慢性感染H9与正常C8166细胞间融合,EC50分别为1.76μg·mL-1和11.95μg·mL-1.雪胆素A和雪胆素B对HIV-l逆转录酶、蛋白酶、NCp7锌离子逐出均没有抑制作用.雪胆素A对HIV-1整合酶有微弱的结合活性,而雪胆素B对HIV-1整合酶没有结合活性.在共培养实验中,雪胆素A和雪胆素B预处理C8166细胞组比未经预处理细胞组能够更有效的抑制HIV-l活性.结论:化合物雪胆素A和雪胆素B体外有较好的抗HIV-1活性,可能主要作用于HIV-1病毒进入细胞阶段.

On the origin and evolution of new genes-a genomic and experimental perspective

The inherent interest on the origin of genetic novelties can be traced back to Darwin. But it was not until recently that we were allowed to investigate the fundamental process of origin of new genes by the studies on newly evolved Young genes. Two indisp

Evolutionary characteristics of exons expressed at different abundance levels in mammals

With comparative genomics approaches, we evaluated the evolutionary characteristics of conservation of exons which are expressed abundantly, moderately or lowly in mammals. Using non-coding regions and pseudogenes as controls, sequence identity, phastCons