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【bio-news】在海洋中存在着成千上万的病毒种类
Hundreds Of Thousands Of Viral Species Present In The World's Oceans
The ocean is full of life--large, small, and microscopic. Bacteriophage (phage) viruses are minute, self-replicating bundles that alter microorganisms' genetic material and moderate their communities through predation and parasitism. Despite their small size, they are astoundingly abundant with about as many of them in a bucket full of seawater as there are humans on the planet. As a result, they can have a huge impact ecologically.
In a new study published online this week in the open access journal PLoS Biology, Florent Angly, Forest Rohwer, and colleagues detail their metagenomic study of the diversity of bacteriophage present in water samples collected from 68 sites over 10 years from four oceanic regions (the Sargasso Sea, the Gulf of Mexico, British Columbia coastal waters, and the Arctic Ocean). They use pyrosequencing (a technique that enables collection of many DNA sequence reads for less cost than conventional sequencing) to large samples, rather than individual organisms to gain insights into diversity, geography, taxonomy, and ecosystem functioning. This approach identified tremendous viral diversity with greater than 91% of DNA sequences not present in existing databases.
Angly and colleagues analyzed the distribution of marine phages among the sampling sites and found a correlation between geographic distance and genetic distance of viral species, supporting the idea that the marine virome varies from region to region. They also investigated how similar the viromes from each location were--in fact, the differences were mostly explained by variations in relative abundance of the viral species, and supports the notion that although everything is everywhere, the environment selects.
Overall, they saw that samples from the British Columbia coast were the most genetically diverse (consistent with its nutrient-rich environment). The other three samples showed increasing diversity with decreasing latitude, a trend that parallels previous findings from terrestrial ecosystems. In fact, the researchers predict that the world's oceans hold a few hundred thousand broadly distributed viral species, with some species-rich regions likely harboring the majority of these species. 本人认领本篇，48小时未交稿，其他战友自由认领 海洋中充满了生命－大的、小的和只有在显微镜下才能看到的生命。噬菌体病毒是一类微小的能够自我复制的囊泡，它们能够通过捕食和寄生改变微生物的遗传物质并节制它们的群落。虽然它们尺寸小，但是他们的数量非常丰富，在一个装满海水的桶里就有象地球上的人数量一样多的噬菌体。所以，从生态学的角度看，它们有着巨大的影响力。
在本周网络杂志PLoS Biology上，公开发表了Florent Angly, Forest Rohwer和他们的同事进行的一项新的研究。他们详细描述了对水标本中的噬菌体种类的多元性基因研究。这些水标本是历时10年从四个大洋（Sargasso海，墨西哥湾，英属哥伦比亚海岸和北冰洋）的68个地点采集的。他们对大样本使用了焦磷酸测序技术（一种能比传统的测序方法检测成本更低且能更多DNA序列的技术），而不是对单个微生物去研究其多样性、地理分布、生物分类和执行生态系(统)机能。这种方法发现大量的病毒种类，超过91%的DNA序列不存在于已知的数据库。
Angly和他的同事分析了取样地点海生噬菌体的分布情况，发现在病毒种类的遗传距离和地理距离间存在着相互关系，这支持了海生病毒体地区与地区间存在变异的观点。他们还调查了每个地点病毒体的相似程度，事实上，在相对丰富的病毒种类中，这些差别都可以用变异来解释，这也支持这样一种观点，即所有的物种普遍分布，但环境具有选择作用。
总之，他们在英属哥伦比亚海岸取得的样本最具遗传多样性（与其营养丰富的环境相符）。其它三个样本随纬度的降低生物多样性逐渐增加，这种趋势与以前在陆地生态系统中的发现类似。实际上，研究者推测在世界的大洋中分布着几十万种病毒物种，而一些物种丰富的地区可能占了这些物种的大部分。 [标签:content1][标签:content2]
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作者:admin@医学,生命科学 2011-06-06 21:39
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