PNAS：首个洞熊基因组测序完成

　　

生物通报道，来自法国能源委员会萨克莱生物学和技术研究所以及法国其他研究机构的科学家利用法国Chauvet的旧石器时代岩画洞中发现的已灭绝的欧洲洞熊的骨头，完成了洞熊线粒体DNA的测序工作。相关的成果公布在10月28日的PNAS上。

 

最近几年，基因组的研究涉及到已灭绝的动物，但是取样仍旧是研究已灭绝的动物基因组的难点之一。现在，获得完整线粒体DNA的只有moa（恐鸟，已灭绝的新西兰巨型鸟），moa在几百年前已经灭绝。在更新世里，猛犸象和乳齿象的基因组研究已经开展，它们的基因组样本可从永久冻土层获得。为了研究更多更新世里的动物线粒体基因组，研究者从法国的一个旧石器时代的岩画洞里找到了已灭绝的欧洲洞熊的骨头。

 

研究者选择了一些来自洞熊（Ursus spelaeus）的胸骨节，通过放射性同位素的检测发现，这些胸骨可追溯到32,000年以前。通过一些零散的DNA片段，研究者拼凑出一个完整的洞熊线粒体DNA序列。

将这些洞熊线粒体DNA序列与西部棕熊进行比对，结果发现，洞熊和棕熊以及北极熊是属于进化树上同一分支上的熊类物种。

 

这一结果对研究物种的进化具有重要意义。

 

原文摘要：Deciphering the complete mitochondrial genome and phylogeny of the extinct cave bear in the Paleolithic painted cave of Chauvet

 

【Abstract】

Retrieving a large amount of genetic information from extinct species was demonstrated feasible, but complete mitochondrial genome sequences have only been deciphered for the moa, a bird that became extinct a few hundred years ago, and for Pleistocene species, such as the woolly mammoth and the mastodon, both of which could be studied from animals embedded in permafrost. To enlarge the diversity of mitochondrial genomes available for Pleistocene species, we turned to the cave bear (Ursus spelaeus), whose only remains consist of skeletal elements. We collected bone samples from the Paleolithic painted cave of Chauvet-Pont d'Arc (France), which displays the earliest known human drawings, and contains thousands of bear remains. We selected a cave bear sternebra, radiocarbon dated to 32,000 years before present, from which we generated overlapping DNA fragments assembling into a 16,810-base pair mitochondrial genome. Together with the first mitochondrial genome for the brown bear western lineage, this study provides a statistically secured molecular phylogeny assessing the cave bear as a sister taxon to the brown bear and polar bear clade, with a divergence inferred to 1.6 million years ago. With the first mitochondrial genome for a Pleistocene carnivore to be delivered, our study establishes the Chauvet-Pont d'Arc Cave as a new reservoir for Paleogenetic studies. These molecular data enable establishing the chronology of bear speciation, and provide a helpful resource to rescue for genetic analysis archeological samples initially diagnosed as devoid of amplifiable DNA.

 

洞熊

    亦名穴熊。古哺乳动物。熊科。身体较现代的熊壮大，体重约一吨。生存于亚欧大陆北部的更新世。

那时的欧亚大陆的山地洞穴附近，往往生存着洞熊（Ursus spelaeus）或其近亲德宁格尔熊（Ursus deningeri），它们都是长达20英尺的大家伙，有着巨大的牙齿、剃刀般锋利的巨爪，性情非常凶猛。直到尼安德特人和较晚期的克鲁马农人在欧洲中东出现, 这些巨大的野兽仍不时骚扰着各个洞穴中的人们。