What are the signals that allow the correct differentiation of neoblast stem cells during planarian regeneration?

研究简单动物的生物学一直是，并将继续，对人类生物学的理解是无价的。我们知道，简单的动物(如苍蝇和蠕虫)使用与人类相同的基本基因和分子来控制许多不同的生物过程。它们不同寻常的生物学使它们成为研究人类生物学某些基本方面的理想对象。简单的动物具有较短的生命周期，这使得进化速度比复杂的动物更快。此外，简单的动物容易接受对复杂的动物(特别是人类！)来说是不适当和不道德的实验方法。在这项研究中，将使用一条爬行动物蠕虫来了解干细胞的基本生物学。干细胞是保留了成为多种不同类型细胞的能力的细胞，如神经、肌肉或皮肤细胞。成年浮游生物的不同寻常之处在于，它们含有大量的干细胞，能够在蠕虫中产生其他所有类型的细胞。例如，上个世纪初的实验表明，如果将一只涡虫切成小块，这些成体干细胞将允许每一块蠕虫再生成一条全新的、尽管更小的蠕虫。长出新的头、胳膊或腿显然是人类做不到的。但我们确实有一些细胞有一定的能力在需要时产生其他类型的细胞，例如，对伤口或瘀伤的反应，我们能够修复和替换受损的细胞。这项研究的目的是了解涡虫的干细胞如何能够分裂，并在新蠕虫的正确位置产生正确的细胞。如果我们能够了解这一过程，我们可能就更接近于了解我们自己再生丢失或受损细胞的能力。这种类型的研究对于了解细胞丢失或受损而需要新细胞的疾病(如阿尔茨海默氏症)，或者像白血病这样的疾病特别重要，因为我们自己的干细胞失控，产生过快或产生错误类型的细胞。事实上，如此多的生物过程在简单的动物之间共享，而且我们已经开发出外部工具来详细研究一个在其生命过程中如此广泛地使用干细胞的动物，这是一个令人兴奋的机会，可以增加我们对干细胞生物学的基本理解。

Studying the biology of simple animals has been, and continues to be, invaluable to the understanding of human biology. We kno wthat simple animals (such as flies and worms) use the same basic genes and molecules that humans use for controlling many different biological processes. Their unusual biology makes them ideal subjects for studying certain basic aspects of our own biology. Simple animals have shorter lifecycles, allowing faster progress than in more complex animals. Additionally, simple animals are amenable to experimental approaches that are inappropriate and unethical in complex animals (particularly humans!). In this study, a planarian worm will be used to understand the basic biology of stem cells. Stem cells are cells that retain the ability to become lots of different types of cell such as nerve, muscle or skin cells. Adult planarians are unusual in that they contain a large number of stem cells which are capable of giving rise to every other cell type in the worm. For example experiments at the beginning of the last century showed that if a planarian is cut into small pieces, these prsence of adult stem cells will allow each piece of the worm to regenerate into a whole new, albeit smaller, worm. Growing a new head, arm or leg is something humans obviously can't do. But we do have cells that have some capacity to generate other cell types when they are needed, for example in response to cuts or bruises we are able to heal and replace damaged cells. The intention of this research is to understand how the planarian worm's stem cells are able to divide and give rise to the right cells at the right place in the new worm. If we can understand this process we may be closer to understanding our own capacity to regenerate lost or damaged cells. This type of research is particularly important for understanding diseases in which cells have been lost or damaged and new cells are needed (such as Alzheimers), or for diseases like leukemia where our own stem cells go haywire and produce too quickly or produce the wrong type of cells. The fact that so many bioogical processes are shared between simple animals and that we have developed exoerimental tools to study the in detail an animal that uses stem cells so extensively during its life course is an exciting opportunity to increase our basic understanding of stem cell biology.