Microinjection materials

Note Although the microinjected material wiU diffuse, we found that four images taken 20 seconds apart showed an average change in fluorescent integrated intensity of only 1.5% (three time points are shown in Figure 18.3b,c,d). This indicates that the total pixel gray-scale value remains essentially constant at early time points after injection and is a reliable indicator of the microinjected volume. 

D invasion of microinjection-derived spheroids in collagen 3-D from 3-D Reproducible, automated, adaptable to other ECM components or fresh tumor biopsy material. 96-well system containing multiple spheroids/weU can be used in HT Specialist equipment needed, multiple spheroids/weU can potentially lead to secreted chemo-attractants (33)... 

Armyworm caterpillars that have been dipped in a solution of the compound will feed normally when offered untreated leaves. Using microinjection techniques, a small amount of solution of 24,055 was placed inside the mouth cavity of the armyworms they fed normally. Injection of the material into the body cavity of the caterpillars also had no effect on their feeding. Thus, feeding seems to be affected only if the insect actually bites and/or tastes the material on its food. 

In some circumstances the introduction of a cloning vector into a host cell is a trivial process. For example, phage vectors are designed so they introduce recombinant DNA in an infective process called transfection, and some bacteria take up plasmids unaided. However, most host cells must be induced to take up foreign DNA. Several methods are used. In some prokaryotic and eukaryotic cells, the addition of Ca2+ to the medium promotes uptake. In others, a process called electroporation, in which cells are treated with an electric current, is used. One of the most effective methods for transforming animal and plant cells is the direct microinjection of genetic material. Transgenic animals, for example, are created by the microinjection of recombinant DNA into fertilized ova. 

Microinjection of flnorochromes, antibodies, proteins and genetic material is widely practiced by biologists despite negative effects on the target and disadvantages associated with insertion of microcapillaries. 

Microinjection Molding Machines, Auxiliary Equipment, and Polymer Materials... 

There are various polymer materials that can be processed by the microinjection molding process, which provides good design flexibilities. In the... 

Among the different gene transfer techniques, microinjection is by far the most efficient procedure. Only microinjection allows the transfer of a known number of test molecules either into the cytoplasm or into the nuclei of the recipient cell Up to 100% of the recipient cells support expression of the transferred material, and stable transformed cell lines can be isolated with a frequency of 20-30%. Biochemical studies can be performed with 50-100 injected cells, and the injected material (e.g., DNA, RNA) can be reisolated and further analyzed by standard techniques (e.g., Southern and Northern blots, electron microscopy) (for review, see Graessmann and Graessmann, 1983 Graessmann et al., 1983 Ceiis et al., 1986). 

Cells are brought into focus and a distinct field is chosen for injection. The capillary is lowered by the manipulator and an individual cell is approached. The cell is injected by further lowering the capillary, and the test material is transferred into the cell by a low pressure exerted with a 50-ml syringe (air-filled) or an automatic injection pump. A small dent is seen at the cell surface when the capillary touches the cell. When the capillary is lowered further, the tip enters into the cell and the dent disappears. Appearance of a white spot indicates that the capillary has penetrated the entire cell and killed the cell. Successful microinjection is marked by slight enlargement of the cell or of the nucleus. 

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