Customised Surface Markers for the Separation of X and Y Bearing Mammalian Sperm

后代性别的预先选择在畜牧业中将是非常有益的。在许多农场物种中，如猪或奶牛，雌性后代在经济上比雄性重要得多，而在其他物种中，如赛马或肉牛，雄性是首选。例如，成年雄性野猪肉可能有一种被称为野猪臭味的“异味”，因此将完整的雄性猪饲养到高体重是不经济的。目前，通过早期屠宰或阉割公猪来避免公猪的污点，这在伦理上是不可取的，也是经济上的浪费。该项目旨在发现在受精发生之前分离携带X染色体（将产生雌性）和携带Y染色体（将产生雄性）的精子的方法。目前，唯一的方法是使用染料染色精子头部的DNA，并将DNA含量较高的精子与DNA含量较低的精子分开-这是因为X染色体略大于Y染色体。这种“流式分选”过程（a）缓慢而繁琐，并且对于某些物种（例如猪）来说在商业上不可行，因为猪需要大剂量的精液进行人工授精，并且（B）涉及对DNA进行染色并在其上照射紫外线激光，这两者都可能潜在地损害DNA。因此，迫切需要更有效和更安全的方法来分离X和Y精子。本项目旨在通过使用现代分子遗传转基因技术来创造产生表达人工表面标记的精子的动物来解决这个问题。这将以这样的方式进行，即只有携带X或Y的精子在表面上具有该标记。然后，标记物可以用于将携带X或Y的精子彼此分离。通过耗尽表达表面标记的精子的精液，这将留下富含不含人工表面标记基因的异性精子的射精群体，以用于繁殖下一代。在牲畜中，这将使精子选择，同时防止转基因生物进入食物链。

The pre-selection of offspring sex would be hugely beneficial in animal husbandry. In many farm species such as pigs or dairy cattle, female offspring are much more economically important than males, while in other species such as racehorses or beef cattle, males are preferred. For example, adult male boar meat can have an "off" flavour known as boar taint, thus making it uneconomical to raise intact male pigs to high weights. Currently, boar taint is avoided by early slaughter or castration of male pigs, which is ethically undesirable as well as economically wasteful. This project seeks to discover ways to separate sperm bearing an X chromosome (which will give females) and those bearing a Y chromosome (which will give males) before fertilisation occurs. Currently, the only way to do this is by using a dye to stain the DNA in the sperm head, and separating the sperm that have more DNA from those that have less - this works because the X chromosome is slightly larger than the Y. This "flow-sorting" process is (a) slow and cumbersome and not commercially viable for some species such as pig where large doses of semen are required for artificial insemination and (b) involves staining the DNA and shining an ultraviolet laser on it, both of which can potentially damage the DNA. There is thus a strong demand for more efficient and safer ways of separating X and Y sperm.This project aims to approach this issue by using modern molecular genetic transgenic techniques to create animals that produce sperm expressing an artificial surface marker. This will be done in such a way that either only X or Y bearing sperm have this marker on the surface. The marker can then be used to separate X or Y bearing sperm from each other. By depleting the semen of sperm that express the surface marker, this will leave an ejaculate population enriched in the sperm of the opposite sex that do not contain the artificial surface marker gene to be used to breed the next generation. In livestock, this would enable sperm selection while preventing genetically modified organisms entering the food chain.