The ability to conveniently construct gene disruptions is an important methodology for genetic analysis of the fission yeast Schizosaccharomyces pombe. Because of the limited number of selectable markers available for generating gene disruptions in fission yeast, the construction of strains that contain multiple gene disruptions can be quite difficult. This becomes a particular problem when epi...

A growth hormone minigene carrying its natural promoter (237 nucleotides of chromosomal DNA) was stably propagated in a murine retrovirus containing hypoxanthine-guanine phosphoribosyltransferase as a selectable marker. Glucocorticoid and thyroid hormone inducibility was transferred with the growth hormone gene. Recombinant virus with titers of 10(6) per milliliter was recovered. This demonstra...

Natural genetic transformation offers a direct route by which synthetic gene constructs can be placed into the single circular chromosome of Streptococcus pneumoniae. However, the lack of a general negative-selection marker has hampered the introduction of constructs that do not confer a selectable phenotype. A 1.3-kb cassette was constructed comprising a kanamycin (Kn) resistance marker (kan) ...

The propagation of recombinant plasmids in bacterial hosts, particularly in Escherichia coli, is essential for the amplification and manipulation of cloned DNA and the production of recombinant proteins. The isolation of bacterial transformants and subsequent stable plasmid maintenance have traditionally been accomplished using plasmid-borne selectable marker genes. Here we describe a novel sys...

We have tested whether the thymidine kinase gene of herpes simplex virus 1 (HSV-1 tk) could function as a negative selectable marker in Leishmania major. Several drug resistance markers have been used for positive selection of transfected DNA in trypanosomatids, including neomycin phosphotransferase (NEO; refs. 1-4) and hygromycin phosphotransferase (HYG; refs. 5,6). Negative selectable markers...

The ribosomal protein L41 gene of Phaffia rhodozyma was cloned and used as a dominant selectable marker for cycloheximide resistance in the transformation of P. rhodozyma. Electrotransformation with a plasmid containing a ribosomal DNA fragment as a targeting signal typically yielded 800 to 1,200 transformants/microgram of DNA with an integrated copy number of about seven per haploid genome.

We have constructed expression vectors for Chinese hamster ovary (CHO) cells that produce both selectable marker and recombinant cDNA from a single primary transcript via differential splicing. These vectors produce stable CHO cell clones that, when pooled, produce abundant amounts of secreted recombinant proteins compared with the amounts produced by conventional expression approaches that hav...