Temporal Dynamics of Dialects in the Whistled Songs of Starlings

Previous studies revealed that whistled songs of starlings can be separated into different categories, among which five themes are found in the repertoires of all (or most) individuals. These “specific” themes show local variations but the different themes have different sizes of dialect areas. This study investigates the temporal evolution of this complex dialectal system. Observations were made in an area where dialects were mapped three years earlier. They reveal an obvious temporal evolution of dialects, although the degree of variation differs according to the theme. No structural change was observed for two themes (CC and ST), but some temporal dynamics in their dialect boundaries did appear. There were changes in the structures and boundaries of two other themes (IT and HT). However, they showed:

• — a relationship between new and old structures, either with persistence of the old variants or with an apparent drift. Almost no really new structures were observed.
• — all the 1980 variants recorded in 1983 were found at sites not far from the original one. The main changes consisted of extensions or regressions of variants along boundaries.

Lastly, the temporal evolution of RT dialects is unusual in that the changes are more sudden. The variants have been replaced by different ones in some cases, but in others they have remained stable. The complexity of the dialectal system is persistent on a temporal level, varying from stability for ST to sudden changes for RT, with IT and HT intermediate.     

Flow cytometry: technical description and some applications in France

After reviewing basic technical considerations, we discuss some applications of flow cytometry in French laboratories. This methodology is used in several areas: oncology, cellular pharmacotoxicology, molecular biology and genetics, immunology, as well as cellular biology and physiology. We also examine the evolution of this technique in two directions: on the one hand, the appearance of increasingly sophisticated instruments; on the other, the development of less expensive and less complicated apparatuses principally directed at clinical applications.     

Promotion of hyphal growth in Ustilago violacea by host factors from Silene alba

Ustilago violacea specifically parasitizes susceptible members of the Caryophyllaceae. We isolated water-soluble compounds from leaves of Silene alba which promoted hyphal development in the dimorphic pathogen. We also isolated hyphal growth promoting -tocopherol from S. alba. The water-soluble activity, which we term hyphal growth factor, or HGF, separated into four bands with gel filtration chromatography and represented over 40% of the total hyphal growth promoting activity isolated from S. alba. The water-soluble HGF activity may be host-specific and may function as a determinant of the host-parasite specificity between U. violacea and caryophyllaceous host plants.Abbreviations HGF Hyphal growth factor - BHT butylated hydroxytoluene     

Cell envelope phospholipid changes in a moderate halophile during phenotypic adaptation to altered salinity and osmotic stress

Abstract The increased content of negatively-charged phospholipids in membranes of Vibrio costicola grown at high salinities is mediated by increased phospholipid synthesis of phosphatidylglycerol relative to phosphatidylethanolamine. This phenomenon provides a system for investigating the factors involved in triggering and controlling haloadaptation in this moderately halophilic bacterium. We review recent experiments, which show that when subjected to sudden increases in external salinity, V. costicola senses both the absolute NaCl concentration and the magnitude of the salt shift. We show that the latter is sensed at least in part via osmotic pressure effects, since shift-up into sucrose-containing media triggers comparable changes in growth and in phospholipid composition and synthesis.     

Antigens associated with various cytotoxic activities of murine peripheral macrophages

BCG- or glucan-elicited murine peripheral macrophages released a cytotoxin in the presence of loach egg lectin, whereas proteose peptone-, glycogen-, or thioglycollate-elicited or resident macrophages did not. The macrophages that released cytotoxin coincided with those that showed lectin-dependent macrophage-mediated cytolysis (LDMC) in response to loach egg lectin. The cytotoxin released by BCG-elicited macrophages in response to loach egg lectin had a molecular weight of 55 K daltons. The macrophages that released cytotoxin and other cytotoxic macrophages such as those that showed LDMC- and antibody-dependent macrophage-mediated cytolysis (ADMC) were examined by using several antibodies to surface antigens of macrophages. The results showed that murine peripheral macrophages could be divided into three types. Resident macrophages (Type I) which had common macrophage antigens (Mac-1 and B12) showed only LDMC in response to wheat germ agglutinin. Some elicited macrophages (Type II) were asialo GM1-positive and showed both ADMC and LDMC in response to wheat germ agglutinin. Activated macrophages (Type III) showed LDMC in response to loach egg lectin and cytotoxin-release, but had no antigen detectable with monoclonal anti-macrophage antibody (C14). These three types of macrophages were clearly distinguished diagrammatically by their roof-shaped, rocket-shaped and irregular-shaped profiles of activities and antigens. These data suggest that several selected surface antigens of macrophages are associated with distinct cytotoxic stages of peripheral macrophages.     

The use of graph theory in analysis of cells and cell nuclei in particular

Application of graph theory to morphological analysis of cells described by n parameters is presented. The analysis takes advantage of the possibility of describing structures in a multi-dimensional space. The method may be useful in determining similarity or differences between studied structures.     

Transport theory for growing cell populations

The partial differential equation that describes the growth of cell populations whose maturation rate is random is developed. The equation resembles that used in classical transport theory but mitotic boundary conditions and the restriction of the maturation rate to non-negative values brings out new features and new problems. This is a generalization of a previously published formulation in which cells could make transitions at random between only two maturation velocities: a characteristic velocity and zero. Growth rates, cycle time distributions and pulsed labeled mitotic curves are calculated for a simple choice of parameters. A numerical algorithm that is suited to the solution of the transport equation is given.