Susan Jean Karcher

• Purdue University West Lafayette

Non-radioactive methods to label nucleic acids to be used as probes are being used more often. Non-radioactive detection methods offer several advantages over the usual radioactive methods. Non-radioactive detection methods eliminate the need to deal with the licensing, waste disposal, and safety concerns associated with the use radioactive materia...

picA is an Agrobacterium tumefaciens chromosomal locus, identified by Mu d11681 mutagenesis, that is inducible by certain acidic polysaccharides found in carrot root extract. Cloning and genetic analysis of a picA::lacZ fusion defined a region of the picA promoter that is responsible for the induction of this locus. Furthermore, we identified a pos...

We used the transposon Mu dI1681 to identify genes on the Agrobacterium tumefaciens chromosome that are inducible by extracts from carrot roots. One such locus (picA, for plant inducible chromosomal), harbored by A. tumefaciens At156, was inducible 10- to 50-fold by these extracts. Mutation of picA had no detectable effect upon bacterial growth or...

A series of plasmids have been constructed in which a promoter from the TR region of the Agrobacterium tumefaciens Ti-plasmid has been fused to genes encoding neomycin phosphotransferase II (NPT II) or a cDNA clone encoding a 22 kd zein protein. After recombination into the Ti-plasmid pTiA6, A. tumefaciens strains harboring these plasmids were used...

The sizes and map positions of five polyadenylated transcripts from the TR region of the octopine-type tobacco crown gall tumor E9 have been determined by Northern blot and S1 nuclease analyses. These RNAs range in size from 780 to 1,600 bases, and their relative abundancies vary according to the growth conditions of the tumor cultures. Different r...

Methylation of the T-DNA in Aqrobacterium tumefaciens and in four octopine-type (A6S/2, E9, 15955/1, 15955/01) and one nopaline-type (HT37#15) crown gall tumors was investigated using the isoschizomeric restriction endo-nucleases Msp I and Hpa II. T-DNA in the octop1ne-type Ti-plasmid pTiB6806 was not methylated at the sequence 5 ‘CCGG3’ in Agrobac...

Microbe Interactions (of which he is now Editor-in-Chief), and served on numerous grant panels for the USDA and NIH. His research interests include Agrobacterium tumefaciens and crown gall tumorigenesis, plant genetic engineering, and plant molecular biology. He has taught undergraduate and graduate level lecture and laboratory courses in plant mol...

where she teaches introductory and upper level genetics and molecular biology laboratory courses and an upper level human genetics lecture course. Her research interests include plant molecular biology, interactions between pathogenic microbes and their host plants, and Agrobacterium tumefaciens. She hosted the 17th annual ABLE workshop/conference...

An easy-to-perform exercise to demonstrate complementation is presented. Complementation tests are used to determine whether mutations affecting the same phenotype are within the same gene (allelic) or in different genes (non-allelic). In this exercise, mutations in the rII locus of bacteriophage T4 are studied. Host E. coli bacteria are co-infecte...

As biology educators, we seek to improve students' abilities to read scientific articles and evaluate them critically. Frequently, we also strive to improve students' writing skills. This mini workshop presented what has worked in a large sophomore-level laboratory in genetics and molecular biology class of 200 biology majors. At Purdue, we have ha...