Effects of post-translational modifications catalysed by pollen transglutaminase on the functional properties of microtubules and actin filaments

TGases (transglutaminases) are a class of calcium-dependent enzymes that catalyse the interactions between acyl acceptor glutamyl residues and amine donors, potentially making crosslinks between proteins. To assess the activity of apple (Malus domestica) pollen TGase on the functional properties of actin and tubulin, TGase was prepared from apple pollen by hydrophobic interaction chromatography and assayed on actin and tubulin purified from the same cell type. The enzyme catalysed the incorporation of putrescine in the cytoskeleton monomers. When tested on actin filaments, pollen TGase induced the formation of high-molecular-mass aggregates of actin. Use of fluorescein– cadaverine showed that the labelled polyamine was incorporated into actin by pollen TGase, similar to with guinea pig liver TGase. The pollen TGase also reduced the enzyme activity and the binding of myosin to TGase-treated actin filaments. Polymerization of tubulin in the presence of pollen TGase also yielded the formation of high molecular mass aggregates. Furthermore, the pollen TGase also affected the binding of kinesin to microtubules and reduced the motility of microtubules along kinesincoated slides. These results indicate that the pollen tube TGase can control different properties of the pollen tube cytoskeleton (including the ability of actin and tubulin to assemble and their interaction with motor proteins) and consequently regulate the development of pollen tubes

Assessment of the use of CAL to replace remedial biochemical calculation tutorials

A number of students at the early stages of our courses have problems with the correct use of units and basic concentration calculations. These problems are easily addressed by remedial tutorials. A PC Computer Assisted Learning (PCCAL) package from Bath University (UK) on "Basic calculations" was loaded onto the Erasmus Darwin network. The programs were used initially with a small group of second year part-time Bachelor of Science Biomedical students (11 students) to assess if the package could replace previously used remedial tutorial time. The part-time students received one introductory tutorial on how to access the programs and their content. In addition, they also undertook a short pre-program test. For the following three weeks the students used the PCCAL program in the Erasmus Darwin computer resource room (ED290) in place of the remedial tutorial. At the end of the tutorial sessions the students were again subjected to a short post-program test and a verbal feedback session. All the students showed an improved score on the test taken after using the computer programs. In the verbal feed back session the students enjoyed the fact that they could work at their own pace on the packages and that the material got progressively harder. It was decided to test the programs' effectiveness with a larger group of students and to link the assessment of the packages to a pre- and post-computer session multiple-choice question (MCQ) test