Variable diameter CO2 laser ring-cutting system adapted to a zoom microscope for applications on polymer tapes.

This paper presents the conception and implementation of a variable diameter ring-cutting system for a CO2 laser with a working wavelength of 10.6 µm. The laser-cutting system is adapted to an observation zoom microscope for combined use and is applicable for the extraction of small circular areas from polymer films, such as forensic adhesive tapes in a single shot. As an important characteristic for our application, the variable diameter ring-cutting system provides telecentricity in the target area. Ring diameters are continuously tunable between 500 µm and 2 mm. A minimum width of less than 20 µm was found for the ring profile edge. The basic characteristics of the system, including telecentricity, were experimentally evaluated and demonstrated by cutting experiments on different polymer tapes and further exemplary samples.

Isolation of viable multicellular glands from tissue of the carnivorous plant, Nepenthes.

Many plants possess specialized structures that are involved in the production and secretion of specific low molecular weight compounds and proteins. These structures are almost always localized on plant surfaces. Among them are nectaries or glandular trichomes. The secreted compounds are often employed in interactions with the biotic environment, for example as attractants for pollinators or deterrents against herbivores. Glands that are unique in several aspects can be found in carnivorous plants. In so-called pitcher plants of the genus Nepenthes, bifunctional glands inside the pitfall-trap on the one hand secrete the digestive fluid, including all enzymes necessary for prey digestion, and on the other hand take-up the released nutrients. Thus, these glands represent an ideal, specialized tissue predestinated to study the underlying molecular, biochemical, and physiological mechanisms of protein secretion and nutrient uptake in plants. Moreover, generally the biosynthesis of secondary compounds produced by many plants equipped with glandular structures could be investigated directly in glands. In order to work on such specialized structures, they need to be isolated efficiently, fast, metabolically active, and without contamination with other tissues. Therefore, a mechanical micropreparation technique was developed and applied for studies on Nepenthes digestion fluid. Here, a protocol is presented that was used to successfully prepare single bifunctional glands from Nepenthes traps, based on a mechanized microsampling platform. The glands could be isolated and directly used further for gene expression analysis by PCR techniques after preparation of RNA.

Single cells for forensic DNA analysis--from evidence material to test tube.

The purpose of this project was to develop a method that, while providing morphological quality control, allows single cells to be obtained from the surfaces of various evidence materials and be made available for DNA analysis in cases where only small amounts of cell material are present or where only mixed traces are found. With the SteREO Lumar.V12 stereomicroscope and UV unit from Zeiss, it was possible to detect and assess single epithelial cells on the surfaces of various objects (e.g., glass, plastic, metal). A digitally operated micromanipulator developed by aura optik was used to lift a single cell from the surface of evidence material and to transfer it to a conventional PCR tube or to an AmpliGrid(®) from Advalytix. The actual lifting of the cells was performed with microglobes that acted as carriers. The microglobes were held with microtweezers and were transferred to the DNA analysis receptacles along with the adhering cells. In a next step, the PCR can be carried out in this receptacle without removing the microglobe. Our method allows a single cell to be isolated directly from evidence material and be made available for forensic DNA analysis.

Micropreparation of single secretory glands from the carnivorous plant Nepenthes.

A rapid mechanical micropreparation technique has been developed to isolate multicellular glands, here from Nepenthes pitchers, based on a microdissection platform. The method is an alternative to laser capture dissection because fresh plant tissue can be used directly without previous fixation. Subsequent experiments, such as polymerase chain reaction (PCR)-based detection of an individual gene encoding a thaumatin-like protein and RNA extraction for gene expression analysis, have been successfully added to prove the quality of the prepared biological material. The procedure described is adaptable to a broad range of plant species and should find wide application in the preparation of multicellular glands or other tissues.