Drosophila melanogaster remains an excellent model system for understanding complex biological processes. This is in large part due to the many tools that can be applied experimentally. The control of transgene expression in Drosophila has been an extremely successful technique for assessing genetic function. P-element mediated germ-line transformation is routinely used to generate novel Drosop...

The introduction of defined mutations into open reading frames (ORF) or non-translated regions of the genome is important to study of the structure-function relationship of amino acid residues in proteins or that of sequence motifs at the genome level. We describe a simple two-step method for the introduction of defined single or multiple point mutations into the genome of Saccharomyces cerevis...

Candida albicans is the most common human fungal pathogen and causes significant morbidity and mortality worldwide. Nevertheless, the basic principles of C. albicans pathogenesis remain poorly understood. Of central importance to the study of this organism is the ability to generate homozygous knockout mutants and to analyze them in a mammalian model of pathogenesis. C. albicans is diploid, and...

A pyrithiamine (PT) resistance gene (ptrA) was cloned from a PT resistant mutant of Aspergillus oryzae and was useful as a dominant selectable marker for transformation of all A. oryzae wild type strain as well as A. nidulans. For further study, we examined whether or not ptrA could be used as the transformation marker in other species of filamentous fungi. Two types of plasmid, which contain p...

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...

The unicellular green alga Chlamydomonas reinhardtii is a model organism that provides an opportunity to understand the evolution and functional biology of the lineage that includes the land plants, as well as aspects of the fundamental core biology conserved throughout the eukaryotic phylogeny. Although many tools are available to facilitate genetic, molecular biological, biochemical, and cell...

Thyroglobulin gene expression was repressed in a rat thyroid cell line transformed with Kirsten murine sarcoma virus. Expression of a dominant selectable marker driven by the thyroglobulin promoter was also inhibited. Somatic cell hybridization of transformed and differentiated thyroid cells resulted in extinction of thyroglobulin gene expression. When transformed cells carrying a dominant sele...