Changes in cell morphology affect the quantification of intercellular communication

The scrape loading and dye transfer (SL/DT) method is a functional assay widely used to evaluate the level of the intercellular communication via gap junction. Initially, the evaluation of the degree of communication was done by counting the rows of fluorescent cells from the scrape. Its substitution by fluorescence distance or area, determinated by morphometric softwares, was proposed as the best way of communication measurement. Considering that normal cells change their morphology during different phases of growth in monolayer cultures we proposed to evaluate the possible influence of the cell morphology changes on the quantification of intercellular communication when the SL/DT method is used. The present data indicates that GJIC capacity should be rather quantified by counting the fluorescent cell rows than by the measurement of the fluorescence distance or area, when the goal is to evaluate the cell communication along different phases of cell culture. Normal cells growing in monolayer culture decrease their diameter according to their final density of saturation, impairing the quantification of GJIC capacity by morphometric analysis.     

Salivary system in leaf-cutting ants (Atta sexdens rubropilosa Forel, 1908) castes: a confocal study

The salivary system in ants is not only limited to digestory functions, but also has important role in the communication. The glands which compose the salivary complex are: the post-pharyngeal, hypopharyngeal, mandibular, and thoracic salivary gland, showing peculiar features which may vary according to the castes the individuals belong to and according to the functions they develop. The present study compared the morphological differences among the glands of Atta sexdens rubropilosa workers, males and queens focused on the organization of microfilaments and microtubules in these ants salivary system. Although the post-pharyngeal gland appeared to be more developed in queens, there were no significant gland differences among the analyzed castes. In what regards to the secretory units of the hypopharyngeal and mandibular glands, the association of F-actin with the collector duct seemed to be strong, being surrounded by a microtubules arrangement. The use of a laser scanning confocal microscopy with immunofluorescence whole mounting preparations revealed itself an efficient instrument for the understanding of the internal morphology of insects.     

Association of Molybdenum Ionic Species with Alumina Surface

The adsorption isotherms at 25, 45, and 65 degrees C of molybdenum solutions of concentration ranges between 10(-3) and 3x10(-2) M(Mo) (pH 4-5) on different alumina samples are investigated. The analysis is conducted using a modified Frumkin isotherm which takes a more realistic account of the lateral interaction between adsorbed species and considers that the adsorption takes place on the most basic OH groups on the surface of alumina. The results are discussed in view of the difference in solutions speciation, and the changes in the pH of the remaining supernatant solutions. The solution temperature, PZC of the used aluminas, the configuration of the basic OH groups on their surface, and the pore structure have been shown to intervene effectively. Copyright 2000 Academic Press.