Biological particles plant cells

Plant transformation techniques allow the delivery of the transforming DNA through the cell wall and plasma and nuclear membranes, without compromising the viability of the cell. Gene delivery can be performed either via a biological vector (plant viruses or bacteria) or by non-biological vector-free procedures (chemical methods, microinjection, particle bombardment, etc.) (Birch 1997). 

There seems to be little more evidence in the literature to allow a more coherent discussion of the effects of surfactants on herbicide activity and explanation of their intrinsic phytotoxicity. It may be that with such a diversity of plant structures the task of rationalizing the activity of surfactants (with the complex pattern of wetting effects, evaporation retardation, solubilization, particle size alteration of precipitated active ingredient, membrane permeability effects and intrinsic biological effects on enzyme systems) will be more daunting than with the relatively simple problem that must be faced with surfactant effects on the human organism. It is likely, however, that study of surfactant effects on plant cells will give useful information to help in the elimination of effects on mammalian cells. 

There is evidence that much of the soluble iron combined as stable organic complexes may not be available for plant growth and clearly the iron in sand, clay particles, volcanic ash, etc., will be biologically unreactive for rapidly growing plant cells. On the other hand particles of ferric hydroxide and phosphate can be utilized by growing algae (Harvey, J. Marine Biol. Assoc. VK., 22 205, 1937 Goldberg, Biol. Bull, 102 243, 1952). 

In Chapter 13, you learned that diffusion is the mixing of gases or liquids resulting from their random motions. Osmosis is the diffusion of solvent particles across a semipermeable membrane from an area of higher solvent concentration to an area of lower solvent concentration. Semipermeable membranes are barriers with tiny pores that allow some but not all kinds of particles to cross. The membranes surrounding all living cells are semipermeable membranes. Osmosis plays an important role in many biological systems such as kidney dialysis and the uptake of nutrients by plants. 

This technique, also referred to as biolistics (biology + ballistics), is a direct DNA delivery method developed by Sandford and co-workers [16-18]. This technique employs microprojectiles or high velocity particles coated with DNA to deliver exogenous genetic material into the target cell or tissue, which is subsequently in vitro cultured, and regenerated to produce mature transformed plants. 

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