新石器时代人骨遗骸中古代DNA的提取及X—Y染色体同源基因片段的PCR扩增

从中国新石器时代人骨遗骸中提取出古代ＤＮＡ。通过聚合酶链式反应技术扩增得到Ｘ－Ｙ染色体上的单考贝同源基因片段。由于扩增的基因片段长度具有性别多态性,从而为古代人骨和牙齿提供了分子生物学的性别鉴定。     

The flickering genes of the last mammoths

Woolly mammoths, Mammuthus primigenius, are arguably the most iconic of the extinct Pleistocene megafauna, and an abundance of large permafrost‐embedded bone and ivory material ( Fig. 1 ) means they were also among the first to yield credible DNA sequences ( Hagelberg et al. 1994 ; Hoss et al. 1994 ). Despite mammoth remains being numerous throughout northern Eurasia and North America, both the earliest and most recent fossils are found in northeast Siberia, with the last known population being confined to Wrangel Island in the Arctic Ocean from around 10,000 years ago until their extinction around 4,000 years ago. The extent to which these Holocene mammoths were descended from the Pleistocene populations of Wrangel Island and the demographic nature of their terminal decline have, until now, remained something of a mystery. In this issue of Molecular Ecology, Nyström et al. (2012) report the first use of autosomal variation to track the decline of the last mammoths and, in doing so, take a significant step towards resolving these questions. The authors genotyped four microsatellite loci in 59 Pleistocene and Holocene mammoths from Wrangel Island and Chukotka in mainland northeastern Siberia and showed that while the Pleistocene‐to‐Holocene transition is associated with a significant reduction in genetic diversity, subsequent levels of variation remain constant until extinction. Such a pattern is somewhat surprising as it indicates that while the last mammoths were confined to only a few Arctic islands, their final extinction on Wrangel Island was not a gradual process resulting from loss of genetic diversity/inbreeding. Instead, it seems they maintained a viable effective population size of around 500 until near their presumably rapid extinction. While the ultimate agent of mammoth extinction remains unknown, the work of Nyström et al. (2012) . suggests that we should be looking for something sudden, like a rapid change in climate/ecology or perhaps the arrival of humans.

Figure 1 Open in figure viewer PowerPoint Sergey Vartanyan during field collection, holding a woolly mammoth tusk found along a river embankment in northeast Siberia (photographer: Diana Solovyeva).     

A system for sex determination from degraded DNA: a useful tool for palaeogenetics and conservation genetics of ursids

In this paper, we characterise three sex-specific genes (ZFX/Y, SRY, AMLX/Y) for all eight extant bear species and propose a new, robust and accurate molecular procedure to identify the sex of bears from non-invasive samples and fossil remains. These materials contain tiny amounts of poorly preserved deoxyribonucleic acid (DNA), leaving Polymerase Chain Reaction (PCR) amplification very prone to contamination and difficult to analyse. By taking into account the ancient DNA requirements, the duplex procedures that we developed are efficient not only on DNA extracted from bear faeces but also on ancient DNA extracted from a brown bear fossil 7,500 years old. Defined specifically for ursids, the procedure for faecal samples (co-amplification of ZFX/Y and SRY markers) appears more accurate than other published procedures, as it prevents cross-amplification of potential ingested prey and contamination (19 non-ursid species tested). This system can be applied to threatened bear populations to improve the reliability of sex-ratio and population-size estimates based on non-invasive samples. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorised users.     

Poly(A) tailing of ancient DNA: a method for reproducible microsatellite genotyping

Microsatellites could be of great potential use in the analysis of ancient remains, but so far such analyses have failed to be reproducible mainly because of the high degree of ancient DNA (aDNA) degradation. During PCR, annealing of the primers to the complementary sequences of microsatellites occurs together with cross-annealing of partially degraded repeated sequences. This could create chimeric alleles that do not correspond to the authentic ones. Here we report a simple method for processing aDNA fragments prior to PCR that greatly reduces the production of chimeric alleles. This approach eliminates aDNA molecules broken within the repeats as targets for Taq polymerase by adding poly(A) tails at the 3(') ends of the DNA fragments, which disrupts the homology in the region and thus prevents annealing out of register. We have analyzed one dinucleotide- (D6S337) and two trinucleotide-containing loci (IT15 and SCA1) using poly(A)-tailed and the same untreated aDNA as template. aDNAs were isolated from 28 human remains, 600 and 7000 years of age. In repeated experiments with untreated aDNAs we obtained three to five times more alleles compared to poly(A)-tailed aDNAs. According to our results, modification of aDNA by poly(A) tailing is an efficient pretreatment for accurate genotyping.     

荷花花蕾cDNA文库构建及质量评价

为理解荷花Nelumbo nucifera花器官转录组表达情况,分别选取不同花型的代表品种‘洪湖红莲’Nelumbo nucifera ‘Honghu Honglian’(单瓣)、‘唐招提寺莲’N. nucifera ‘Tangzhaotisi Lian’(重瓣)和‘千瓣莲’N. nucifera ‘Qianban Lian’(千瓣及全重瓣)的花蕾为材料分离mRNA,利用SMART技术合成双链cDNA,经限制性内切酶SfiI酶切后回收去掉接头和500 bp以下片段的cDNA。将cDNA与pUC19载体连接,构建荷花花蕾cDNA文库。经检测,该文库容量为1.12 × 106 pfu·mL-1,插入片段大小集中在500～2000 bp,重组率为95%。该文库的成功构建为荷花花蕾期转录组数据的开发及其花器官发育相关基因的功能研究奠定了分子基础。     

A two-way gas transport system in Nelumbo nucifera

Abstract The aquatic vascular plant Nelumbo nucifera Gaertn. is able to improve its oxygen supply to the submerged and buried organs by a thermo-osmotic gas transport. Investigations with tracer gas and oxygen measurements have shown that thermo-osmotic gas transport exists in N. nucifera when there is a temperature difference between the lacunar air of the leaves and the surrounding atmosphere. The gas transport was increased by up to 935% when a temperature difference of 2.9 ± 1.0 K was detected. Lacunar pressure of up to 166 ± 44 Pa was measured in both young and old leaves. In contrast to the flow-through ventilation system recently described for Nuphar lutea and Nymphoides peltata, a two-way flow in separate air canals in the petioles of both young and old Nelumbo leaves may carry oxygen-rich air down to the rhizome and excess air back to the atmosphere. Anatomical investigations have shown that, in Nelumbo, the two largest air canals of the petiole end directly under the mesh system of the centre plate. These large air canals are proposed to be predominant in the upward flow of air in sunlight. The other air canals of the petiole veer into the leaf blade well below the centre plate. The gas flow system through fresh leaves may carry as much as 10.3 ± 4.5 cm³ air per minute to the buried rhizome.     

牙齿残留物反映的闽西新石器时代人类食谱

本项目对福建闽西地区奇和洞与南山两处新石器时代遗址出土古人类牙齿进行了表面残留物提取与鉴定,通过对其中淀粉粒残留物的种类与数量对比,讨论了全新世初期至中期闽西地区古人类对植物资源的利用方式。这些古人类牙齿表面包含四大类形态不同的淀粉粒:1)多面体形;2)圆形或椭圆形;3)圆锥形;4)水滴形。这些淀粉粒分别代表了禾本科植物种子、植物地下根茎部分和疑似的坚果类,这些都是古人类容易获得的野生食物资源,在新石器时代古人类的饮食中占据着重要的地位。     

消息与动态

1989年2月,该县农民在西牛角峪村采石中,发现少量的动物化石。它们埋藏于石灰岩裂隙的红色粘土中,经中国科学院古脊椎动物与古人类研究所研究人员鉴定为哺乳动物化石的肢     

Mitochondrial DNA evidence for the spread of Pacific rats through Oceania

In the 10 years since we published our first full analysis of mitochondrial DNA (mtDNA) variation in Rattus exulans as a means for tracking human migration in Polynesia, we have extended the commensal approach through time and space with the use of ancient DNA (aDNA) and by analysing samples from across the Pacific. Not only can mtDNA phylogenies provide information regarding population origins and paths of migration, they have also provided information regarding degrees of contact and interaction between islands. An important extension of the R. exulans project is the creation and on-going development of a genetic database for the identification of Rattus species based on mtDNA sequences. The phylogenetic analysis of sequences from 18 species and 1 subspecies of Rattus thus far have raised some questions regarding species identification and species distributions in the Pacific.