Eugen S. Gander

On the chromatin structure of Trypanosoma cruzi.

The chromatin structure of Trypanosoma cruzi was investigated. It was found that, as in other eukaryotes, the chromatin is organized in repeating units, the nucleosomes containing about 200 base pairs of DNA associated with histones. While there is no difference in the DNA size in nucleosomes from T. cruzi and from rat liver nuclei, the histone population of T. cruzi differs in various aspects. Of particular interest is the presence of two basic proteins, possibly histone H1 subcomponents, with very high electrophoretic mobilities.

A cDNA Sequence Coding for a Glutamic Acid-Rich Protein Is Differentially Expressed in Cassava Storage Roots

We report the isolation and characterization of a cDNA sequence (Mec1) coding for a glutamic acid-rich protein (Pt2L4) from cassava storage roots. Comparative sequence analysis showed a high identity of Pt2L4 with cassava protein C54, which is expressed in vascular tissues of storage roots. Northern blot analysis showed that the Mec1 transcript expression pattern might be related to the maturation of the storage parenchyma cells.

Ribosomes and ribosome-function in the midgut cells of Aedes aegypti L.

Abstract A method for the preparation of free and membrane-bound ribosomes from mosquito intestinal cells was developed and applied for the quantification of these two ribosome populations during an entire digestive cycle of female Aedes aegypti. It was found that the number of free ribosomes increases up to 24 hr after food uptake and then stays constant for a further 24 hr. The number of bound ribosomes increases up to 36 hr after food uptake. Then both populations decrease and reach the values of the unfed controls after 96 hr of digestive activity. The quantitative pattern of appearance of the membrane-bound ribosomes could be correlated with the enzymatic activity of a defined class of proteins, the trypsin-like enzyme.

Optimization of a protein synthesizing lysate system from Trypanosoma cruzi

A protein-synthesizing lysate system from Trypanosoma cruzi epimastigotes analogous to the rabbit reticulocyte lysate system was established. The system was optimized by the ‘classical’ method where one of the factors is varied while the others are kept constant. With this the following optima were found: [Mg2+]: 1.0 mM, [K+]: 60 mM, T: 25°C, pH: 7.5. This method was compared with the ‘sequential simplex’ method [Long, D.E. (1969) Anal. Chim. Acta 46, 93–100], a method designed to optimize rationally interdependent factors in biological systems. The optima as determined with this method were: [Mg2+]: 1.02 mM, [K+]: 63 mM, T: 25.5°C, pH: 7.25. At these values the system incorporated 43% more amino acids into proteins than a system optimized with the ‘classical’ method. Fluorographic analysis of the proteins synthesized by the system shows that while proteins in the molecular weight range between 14 000 and 45 000 are synthesized in amounts comparable to the in vivo situation, the higher molecular weight proteins (>45 000) are synthesized in lesser quantities.