Sample information

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Methods

During the preperation in the Lab for the Gel electrophoresis, we committed the mistake of having moved the little DNA we had won from the Lasius many times. We believe that this process lead to an adulteration of the expected results, which are therefore invalid. To however understand our procedure and our results, we have noted the numbers of the gel and our full protocol in the following:

GEL:

1. Lasius

3. Sphaerophoria

4. Dermestidae

+. Wolbachia positiv tested Insect

-. Wolbachia negativ tested Insect

Technical Overview of the Procedure

This DNA extraction protocol is based on a widely used cell lysis technique described by Edwards et al. (1991). The purpose of each step is explained below.

Sample Preparation

Each sample is rinsed with water to remove any alcohol-based preservative.

Cell Lysis

Each sample is soaked in a cell lysis solution called Edwards Buffer, which breaks open the cell and nuclear membranes. This releases the DNA, but also exposes it to proteases such as nucleases that can degrade it. Therefore, the lysis buffer contains several components that both lyse the cells and inhibit nuclease activity:

• EDTA: Destabilizes the cell membrane and inhibits nuclease activity
• SDS: Disrupts membranes and denatures proteins
• NaCl: Separates proteins from DNA and keeps proteins and SDS dissolved to prevent co-precipitation with DNA
• Tris: Maintains a stable pH in the lysis buffer and helps destabilize membranes

Removal of Cellular Debris

To obtain purified DNA, cellular debris is removed by centrifugation. At this stage, the DNA remains dissolved in the lysis buffer and stays in the supernatant.

DNA Precipitation and Purification

This protocol includes both an isopropanol precipitation step and an ethanol wash. Cold isopropanol rapidly precipitates the DNA, while the ethanol wash removes excess salts and other alcohol-soluble biomolecules. The ethanol wash also reduces the time needed to air-dry the DNA pellet.

DNA Elution

The DNA elution buffer dissolves genomic DNA and protects it from degradation. For most laboratory applications, including PCR, a TE-based buffer (containing Tris and EDTA) is preferred over water because it dissolves DNA more efficiently and protects it from nuclease activity as well as repeated freeze–thaw cycles

Results

Due to errors that are likely to have occured during the extraction and procedure of the DNA, we believe that the Gel image showes a wrong depiction of the genetic information.