In this article a homemade spectrophotometer that can be made of inexpensive components available to everyone is presented. This apparatus can be used to implement several low cost standard biochemical and biological experiences like quantitation of biomolecules, the study of biological pigments, and following the time plot of an enzymatic reaction or the growing kinetics of microorganisms.Spectrophotometers are usually at hand at University teaching laboratories, but this is not always the case for high school institutions. The same is true of substances that are commonly available in biochemical teaching experiments. In this work, our aim is to show that basic biochemical colorimetric experiments and demonstrations can be done with a homemade spectrophotometer that is easy and inexpensive to build. In the same spirit, we provide examples of experiments that can be performed with ordinary and fairly inexpensive substances.A spectrophotometer is an apparatus intended to measure the degree of absorbance of light in specific wavelength ranges. It consists of three essential elements, a light source, a monochromator, and a detector. The light source and detector define the limits of wavelength and sensitivity of the apparatus, whereas the monochromator separates the light produced by the light source into different small ranges, usually in the nanometer scale. The sample, placed between the monochromator and the detector (usually in a transparent container called a cuvette), is illuminated by a specific range of wavelengths, and the intensity of the light not absorbed by the substances present in the sample can be quantified by the detector. A more detailed discussion on spectrophotometers and spectroscopy can be found in Refs. 1 and 2.

A specific multiplex PCR was developed for the rapid and highly sensitive quality control of the viral DNA during Epinotia aporema granulovirus (EpapGV) production. At the beginning of this work only 2.3% of the EpapGV genomic sequence was known. In order to increase the availability of specific information, the terminal sequences of the inserts of several selected clones of EpapGV genomic libraries were determined. These data comprised 8.4% of the total DNA sequence and corresponded to regions distributed throughout the genome. Based on the small fraction of known sequence available a set of 32 primers was designed, using information theory to set the basis for this study. Each pair of designed primers was initially tested in individual PCRs to assess the correct size of the expected product and the sensitivity of the amplification. The specificity was verified in multiplex PCRs, using alternatively 1-3 sets of selected 5-6 primer pairs and EpapGV DNA preparations from different sources and degrees of purity. The results indicate that the multiplex PCR could be used for quality control in the bioinsecticide production, as well as in other applications such as the detection of latent infections in E. aporema colonies, and studies related to virus distribution, vertical transmission, host range, or persistence in the field.

The preparation of 2', 3'-di-O-hexanoyluridine (2) by a Candida antarctica B lipase-catalysed alcoholysis of 2', 3', 5'-tri-O-hexanoyluridine (1) was optimised using an experimental design. At 25 ºC better experimental conditions allowed an increase in the yield of 2 from 80% to 96%. In addition to the yield improvement, the volume reaction could be diminished in a factor of 5 and the reaction time significantly shortened