Abstract: A preparation method for mutant cells with deletion of target genes, at least comprising the following steps: (1) transfecting a sgRNA group into same host cells, where the sgRNA group includes two sgRNAs that target different sites of a same target gene, and the number of the sgRNA group may be one or more than one. When the number of the sgRNA group is more than one, each different sgRNA group targets one different target gene. (2) Enriching the host cells expressing one or more sgRNA groups. (3) Culturing the host cells obtained from step (2) to produce mutant cells with deletion of target genes.

Abstract: This invention provides an isolated nucleic acid molecule which encodes a wildtype or mutated HOP-1. This invention also provides a purified wild-type HOP-1 protein or a purified mutated HOP-1 protein. This invention also provides a method for production of an antibody capable of binding to wild-type HOP-1 or mutated HOP-1 protein. This invention also provides an antibody capable of specifically binding to wild-type HOP-1 or mutated HOP-1. This invention also provides a transgenic animal comprising the isolated nucleic molecule encoding HOP-This invention also provides Caenorhabditis elegans mutants in the endogenous hop-1 gene and various method to produce such mutants. This invention also provides a method for identifying a compound which is capable of ameliorating Alzheimer's disease. This invention also provides a method for determining whether a compound is capable of ameliorating Alzheimer's disease. This invention also provides a method for producing suppressors of a hop-1 allele.