It is clear that the construction of large insert DNA libraries is important for map-based gene cloning, the assembly of physical maps, and simple screening for specific genomic sequences. The bacterial artificial chromosome (BAC) system is likely to be an important tool for map-based cloning of genes since BAC libraries can be constructed simply and analyzed more efficiently than yeast artificial chromosome (YAC) libraries. BACs have significantly expanded the size of fragments from eukaryotic genomes that can be cloned in Escherichia coli as plasmid molecules. To facilitate the isolation of molecular-biologically important genes in Ashbya gossypii, we constructed Ashbya chromosome-specific BAC libraries using pBeloBAC11 and pBACwich vectors with an average insert size of 100 kb, which is equivalent to 19.8X genomic coverage. pBACwich was developed to streamline map-based cloning by providing a tool to integrate large DNA fragments into specific sites in chromosomes. These chromosome-specific libraries have provided a useful tool for the further characterization of the Ashbya genome including positional cloning and genome sequencing.
Ascomycota* ; Chromosomes, Artificial, Bacterial ; Chromosomes, Artificial, Yeast ; Clone Cells ; Cloning, Organism ; DNA ; Escherichia coli ; Gene Library ; Genome ; Mass Screening ; Plasmids

The mammary gland bioreactor has great commercial value, but the examples for high level expression of foreign gene were so few that the most examples were not suitable for commercial program. The key resolution for improving the expression level of foreign gene is the construction of expression vector for mammary gland bioreactor. Nearly, many new ideas and new methods about the construction of expression vector were presented, the article summarized them.
Animals ; Animals, Genetically Modified ; Bioreactors ; Breast ; metabolism ; Chromosomes, Artificial, Yeast ; Gene Expression ; Gene Targeting ; methods ; Genetic Vectors ; Humans