Development of a highly efficient system for assessing recombinant gene expression in plant cell suspensions via Agrobacterium tumefaciens transformation

A transient gene-expression system was developed and used to characterize promoter strength, to verify suitability of bacterial gene modifications for expression in plant cells, and to express active antibody molecules. The system is based on suspension tobacco cells transformed by Agrobacterium in a transient way. Conditions such as pre-culture of tobacco cells and the co-cultivation period were identified as determinants to achieve high expression levels. Under established conditions the activity strength of CaMV (cauliflower mosaic virus) 35 S and ToMoTV (tomato mottle taino virus) AL1 promoters were compared. A modified cry gene sequence from Bacillus thuringiensis was expressed and detected by Western-blot analysis. A monoclonal antibody against anti-(hepatitis B virus surface antigen) was produced in such quantities as to allow testing of biological activity and preliminary characterization.

Immunoreactive leukotrienes in nettle plants (Urtica urens)

In order to clarify the mechanisms of urtication after contact with stinging plants, nettle (Urtica urens) hair and whole-plant extracts were examined for the presence of leukotriene (LT) B4 and LTC4 by reverse phase high-pressure liquid chromatography (RP-HPLC) and radioimmunoassay (RIA) and for in vitro neutrophil chemotactic activity and histamine contents. Both hair and plant extracts contained high levels of LTB4 and LTC4 by RIA as well as histamine. The presence of LTB4 was supported by RP-HPLC elution profiles and by in vitro chemotaxis. Nettle hairs therefore resemble insect venoms and cutaneous mast cells with regard to their spectrum of mediators.

Observations on the idioblasts of Dieffenbachia

The toxicity of the Arum genus, especially the Dieffenbachia, has long been a topic of controversy. Some believe that the injury inflicted is primarily mechanical, the result of needle like crystals of calcium oxalate (raphides) found in the stems and leaves. Others cite evidence supporting the existence of enzymatic and allergic injury. This paper describes a hitherto neglected third factor, specialized cells which can forcibly shoot the raphides and which may be necessary for the toxic effect since raphide containing plants devoid of these cells are not toxic. The effects of physical and chemical factors on the behavior of these cells are described.