Biomedical subjects

N Gutterson

Publications and source records attributed to N Gutterson.

4 recordsLinked to original sources

PubMed2003

Cost-effective in vitro propagation methods for pineapple.

We have developed an efficient and cost-effective method for commercial micropropagation of Smooth Cayenne pineapple. In vitro shoots were used as starting materials, and either longitudinal sections of the shoots or leaf bases were used as the explants to regenerate shoots. When these explants were used, the axillary meristems, which usually remain quiescent during shoot multiplication, were able to form new shoots. Subsequent to the regeneration step, additional multiplication was achieved inside a 10-l Nalgene vessel with shoots immersed in liquid medium for 5-10 min/h (periodic immersion bioreactor, PIB). The shoots were then induced to form roots and transferred to soil. Using the above micropropagation method and the PIB, we produced 6,000-8,000 shoots from two initial shoots in less than 6 months. The clonal fidelity of propagated plants was tested in Costa Rican and Indonesian pineapple farms.

Ananas↗

PubMed1999

A simple method to enrich an Agrobacterium-transformed population for plants containing only T-DNA sequences.

A simple modification to standard binary vector design has been utilized to enrich an Agrobacterium-transformed population for plants containing only T-DNA sequences. A lethal gene was incorporated into the non-T-DNA portion of a binary vector, along with a screenable marker. The resulting class of vectors is designated as NTL T-DNA vectors (non-T-DNA lethal gene-containing T-DNA vectors). The lethal gene used here is a CaMV 35S-barnase gene with an intron in the coding sequence (barnase-INT); the screenable marker is a pMAS-luciferase gene with an intron in the coding sequence (LUC-int). To evaluate the utility of this vector design, tobacco plants were transformed with either the NTL T-DNA vector or a control vector from which most of the barnase-INT gene was deleted. Populations of 50 transgenic plants were scored for LUC expression. The results indicated a dramatic reduction in the presence of non-T-DNA sequences in the transgenic population using the NTL T-DNA vector. Only one transgenic plant was found to be LUC+ using the NTL vector, compared with 42 of 50 plants using the control vector. Importantly, the efficiency with which transformed tobacco plants was obtained was reduced by no more than 30%. The reduction in LUC+ transgenics was partially reversed when a barstar-expressing tobacco line was transformed, indicating that barnase expression was responsible for the reduced frequency of incorporating non-T-DNA sequences. Similar transformation results were obtained with tomato and grape. The incorporation of a barnase-INT gene outside the left border appears to provide a generally applicable tool for enriching an Agrobacterium-transformed population for plants containing only T-DNA sequences.

Bacterial Proteins↗

PubMed1988

Genetic determinants for catabolite induction of antibiotic biosynthesis in Pseudomonas fluorescens HV37a.

Antibiotic biosynthesis is regulated by glucose in Pseudomonas fluorescens HV37a. Fusions between antibiotic biosynthetic operons (afu operons) and the Escherichia coli lac operon were isolated to evaluate the genetic determinants for the regulation of antibiotic biosynthesis. Four afu transcriptional units were defined, afuE, afuR, afuAB, and afuP. The afuE and afuR transcripts were promoted divergently at one locus and were catabolite induced, by 250-fold and 5-fold, respectively; the afuAB and afuP transcriptional units were not linked to the others and were not catabolite induced. Thus, regulation of afuE and afuR operon transcription is apparently the mechanism whereby glucose regulates antibiotic biosynthesis. Catabolite induction of the afuE and afuR transcriptional unit was dependent on the products of the afuA, afuB, and afuP genes. Expression of the afuE transcriptional unit was altered quantitatively in afuE mutants. Apparently the afuE transcriptional unit is regulated, at least in part, by its own gene products. Under inducing conditions, expression of the afuE, afuR, and afuP transcriptional units increased rapidly during a 6-h period.

Antifungal Agents↗

PubMed1987

An efficient mobilizable cosmid vector, pRK7813, and its use in a rapid method for marker exchange in Pseudomonas fluorescens strain HV37a.

We describe the construction and utilization of a new mobilizable cosmid vector. Using this vector, mobilizable libraries of bacterial DNA can be efficiently made without a need for size fractionation of target DNA. The low stability of this vector in Pseudomonas fluorescens makes it useful in a rapid strategy, which is not dependent on plasmid incompatibility, for recombining transposon-induced mutations into the bacterial chromosome.

Cosmids↗