Astrocladistics: A Phylogenetic Analysis of Galaxy Evolution I. Character Evolutions and Galaxy Histories

This series of papers is intended to present astrocladistics in some detail and evaluate this methodology in reconstructing phylogenies of galaxies. Being based on the evolution of all the characters describing galaxies, it is an objective way of understanding galaxy diversity through evolutionary relationships. In this first paper, we present the basic steps of a cladistic analysis and show both theoretically and practically that it can be applied to galaxies. For illustration, we use a sample of 50 simulated galaxies taken from the GALICS database, which are described by 91 observables (dynamics, masses and luminosities). These 50 simulated galaxies are indeed 10 different galaxies taken at 5 cosmological epochs, and they are free of merger events. The astrocladistic analysis easily reconstructs the true chronology of evolution relationships within this sample. It also demonstrates that burst characters are not relevant for galaxy evolution as a whole. A companion paper is devoted to the formalization of the concepts of formation and diversification in galaxy evolution.     

Somatic and germinal chimerism after the intracoelomic graft of quail splanchnic mesoderm to chick embryos]

The splanchnic mesoderm of the genital area can develop in coelomic graftings as soon as it is colonized by the primordial germ cells (stage 15 of H. and H.). Heterospecific associations between Chick and Quail embryos lead to the differentiation of gonads showing more or less pronounced somatic and germinal chimerisms.     

A cell line particularly susceptible to bovine enteric Coronavirus replication: HRT 18 cells

Bovine enteric Corona virus (BEC) multiplies spontaneously with very high efficiency in HRT 18 cells; this line established from human rectum adenocarcinoma presents some properties of the differentiated brush border cell of the intestinal villi. Titers obtained are very high (5 x 10(7) TCID 50/ml virus strain F15). The virus produced had the characteristic of BEC: shape, spikes, density 1.19, hemadsorption and hemagglutination of rat erythrocytes. Human and dog enteritic corona viruses replicate also in HRT 18 cells.