Preparation of Solutions and Reagents

The ability to prepare accurate solutions, reagents, and buffers will determine the outcome of a successful experiment. Much time and effort spent in a lab will consist of making solutions, reagents, and buffers. This chapter introduces and refreshes the skill of making solutions including: molarity (M) concentration, percentage (%) concentration, mass/volume concentrations, X-factor concentration, working concentrations from stock solutions, conversions from percentage (%) to molarity (M) concentration, and conversions from molarity (M) to percentage (%) concentration. Basic formulas and examples for how to make solution concentrations are covered.

Identification of Tf1 integration events in S. pombe under nonselective conditions

Integration of retroviral elements into the host genome is a phenomena observed among many classes of retroviruses. Much information concerning the integration of retroviral elements has been documented based on in vitro analysis or expression of selectable markers. To identify possible Tf1 integration events within silent regions of the Schizosaccharomyces pombe genome, we focused on performing an in vivo genome-wide analysis of Tf1 integration events from the nonselective phase of the retrotransposition assay. We analyzed 1000 individual colonies streaked from four independent Tf1 transposed patches under nonselection conditions. Our analysis detected a population of G418(S)/neo(+) Tf1 integration events that would have been overlooked during the selective phase of the assay. Further RNA analysis from the G418(S)/neo(+) clones revealed 50% of clones expressing the neo selectable marker. Our data reveals Tf1's ability to insert within silent regions of S. pombe's genome.

A long terminal repeat retrotransposon of fission yeast has strong preferences for specific sites of insertion

The successful dispersal of transposons depends on the critical balance between the fitness of the host and the ability of the transposon to insert into the host genome. One method transposons may use to avoid the disruption of coding sequences is to target integration into safe havens. We explored the interaction between the long terminal repeat retrotransposon Tf1 and the genome of the yeast Schizosaccharomyces pombe. Using techniques that were specifically designed to detect integration of Tf1 throughout the genome and to avoid bias in this detection, we generated 51 insertion events. Although 60.2% of the genome of S. pombe is coding sequence, all but one of the insertions occurred in intergenic regions. We also found that Tf1 was significantly more likely to insert into intergenic regions that included polymerase II promoters than into regions between convergent gene pairs. Interestingly, 8 of the 51 insertion sites were isolated multiple times from genetically independent cultures. This result suggests that specific sites in intergenic regions are targeted by Tf1. Perhaps the most surprising observation was that per kilobase of nonrepetitive sequence, Tf1 was significantly more likely to insert into chromosome 3 than into one of the other two chromosomes. This preference was found not to be due to differences in the distribution or composition of intergenic sequences within the three chromosomes.

A gene for recessive nonsyndromic sensorineural deafness (DFNB18) maps to the chromosomal region 11p14-p15.1 containing the Usher syndrome type 1C gene

Autosomal recessive nonsyndromic sensorineural deafness segregating in a large consanguineous Indian family was mapped to chromosome 11p14-p15.1 defining a new locus, DFNB18. A maximum lod score of 4.4 at theta = 0 was obtained for the polymorphic micro-satellite marker D11S1888. Haplotype analysis localizes this gene between markers D11S1307 and D11S2368, which is approximately 1.6 cM and encompasses the region of Usher syndrome type 1C (USH1C). We postulate that DFNB18 and USH1C are allelic variants of the same gene.

The largest subunit of mouse RNA polymerase II (RPB1) functionally substituted for its yeast counterpart in vivo

The full-length mouse RNA polymerase II (pol II) largest subunit (RPB1) gene was used to replace 5070 bp of the yeast Saccharomyces cerevisiae RPB1 gene via homologous recombination and gene replacement in vivo. Transcription of the mouse RPB1 gene using the yeast promoter in the haploid state was confirmed by Northern analysis. This strain of yeast is viable, indicating that mouse RPB1 is able to interact functionally with the other yeast RNA pol II subunits in vivo.