Protoplast

Abstract: Intact yeast cells treated with alkali cations took up plasmid DNA. Li+, Cs+, Rb+, K+, and Na+ were effective in inducing competence. Conditions for the transformation of Saccharomyces cerevisiae D13-1A with plasmid YRp7 were studied in detail with CsCl. The optimum incubation time was 1 h, and the optimum cell concentration was 5 x 10(7) cells per ml. The optimum concentration of Cs+ was 1.0 M. Transformation efficiency increased with increasing concentrations of plasmid DNA. Polyethylene glycol was absolutely required. Heat pulse and various polyamines or basic proteins stimulated the uptake of plasmid DNA. Besides circular DNA, linear plasmid DNA was also taken up by Cs+-treated yeast cells, although the uptake efficiency was considerably reduced. The transformation efficiency with Cs+ or Li+ was comparable with that of conventional protoplast methods for a plasmid containing ars1, although not for plasmids containing a 2 microns origin replication. Images

Abstract: The transient gene expression system using Arabidopsis mesophyll protoplasts has proven an important and versatile tool for conducting cell-based experiments using molecular, cellular, biochemical, genetic, genomic and proteomic approaches to analyze the functions of diverse signaling pathways and cellular machineries. A well-established protocol that has been extensively tested and applied in numerous experiments is presented here. The method includes protoplast isolation, PEG-calcium transfection of plasmid DNA and protoplast culture. Physiological responses and high-throughput capability enable facile and cost-effective explorations as well as hypothesis-driven tests. The protoplast isolation and DNA transfection procedures take 6-8 h, and the results can be obtained in 2-24 h. The cell system offers reliable guidelines for further comprehensive analysis of complex regulatory mechanisms in whole-plant physiology, immunity, growth and development.

Abstract: The production and regeneration of bacterial protoplasts promoted the loss of three different plasmid-specified traits in Streptococcus lactis subsp. diacetylactis strains. The loss of five different plasmids, including small multicopy molecules, was readily detected in Streptococcus lactis 712 by screening lysates of random protoplast regenerants on agarose gels. In this strain sequential rounds of protoplast regeneration were used to produce a plasmid-free strain and derivatives carrying only single molecules from the plasmid complement. During these experiments a 33-megadalton plasmid, pLP712, was found to encode genes for lactose and protein utilization. Only this plasmid was required for normal growth and acid production in milk; the remaining four plasmids appeared to be cryptic. Lactose-defective derivatives of a strain carrying only pLP712 were readily isolated. Although these derivatives included instances of plasmid loss, deletions of pLP712 were frequently found. Many different deleted derivatives of pLP712, including some in which the lactose or protein utilization determinant or both were lost, were isolated. The molecular instability of pLP712 largely accounted for previous observations of plasmid complements in S. lactis 712 after lactose determinant curing or transfer by conjugation and transduction. Curing of cryptic molecules from multiple plasmid complements by protoplast regeneration may prove to be generally valuable in lactic streptococci and other gram-positive species.

Abstract: The luciferase gene from the firefly, Photinus pyralis, was used as a reporter of gene expression by light production in transfected plant cells and transgenic plants. A complementary DNA clone of the firefly luciferase gene under the control of a plant virus promoter (cauliflower mosaic virus 35S RNA promoter) was introduced into plant protoplast cells (Daucus carota) by electroporation and into plants (Nicotiana tabacum) by use of the Agrobacterium tumefaciens tumor-inducing plasmid. Extracts from electroporated cells (24 hours after the introduction of DNA) and from transgenic plants produce light when mixed with the substrates luciferin and adenosine triphosphate. Light produced by the action of luciferase was also detected in undisrupted leaves or cells in culture from transgenic plants incubated in luciferin and in whole transgenic plants "watered" with luciferin. Although light was detected in most organs in intact, transgenic plants (leaves, stems, and roots), the pattern of luminescence appeared to reflect both the organ-specific distribution of luciferase and the pathway for uptake of luciferin through the vasculature of the plant.

Abstract: We have recovered transgenic rice plants from a number of commercially important cultivars, including until now recalcitrant Indica varieties, using electric discharge particle acceleration Immature embryos from greenhouse–grown plants were bombarded with gold particles carrying DNA, and transgenic plants were recovered following a simple culture protocol Mendelian segregation of foreign genes was observed in R1 progeny and stable integration was demonstrated by Southern blot analysis of genomic DNA isolated from progeny plants Alternative transformation protocols that are dependent on the development of protoplast and suspension culture systems are no longer necessary as we have shown that a wide variety of diverse cultivars can be transformed Transgenic plants expressing agronomically useful traits such as herbicide resistance have been obtained and are currently undergoing further evaluation This report also demonstrates that it is possible to produce transgenic monocoty–ledonous plants by transforming scutellar tissue of immature embryos