Nous étudions les grandes cartes aléatoires uniformes à une face dont le genre croît linéairement avec nombre d’arêtes, qui sont un modèle de géométrie hyperbolique discrète. Dans des travaux précédents, plusieurs propriétés géométriques hyperboliques ont été étudiées. présent travail, nous petits cycles dans carte unicellulaire uniforme grand genre, et montrons qu’il converge vers distribution...

The evolution of multicellular life requires cooperation among cells, which can be undermined by intra-group selection for selfishness. Theory predicts that selection to avoid non-cooperators limits social interactions among non-relatives, yet previous evolution experiments suggest that intra-group conflict is an outcome, rather than a driver, of incipient multicellular life cycles. Here we rep...

The intramandibular glands of workers and queens of Melipona quadrifasciata Lepeletier (Hymenoptera: Apidae), at different ages and from different functional groups, were studied using light and transmission electron microscopy. The results demonstrated that these glands are composed of two types of secretory structures: 1.A hypertrophied epidermis on the dorsal side of the mandible that is an ...

Unicellular organisms require more energy and materials for their survival than multicellular organisms. A unicellular organism is exposed to environments all around and thus has to protect itself against the effects of the environment on all sides. However, in multicellular organisms all the cells are not in direct contact with the environment and specific cells take up the protective function...

Although mitochondrial transformation is highly desirable in mammals and plants, it is only possible in two unicellular organisms, the budding yeast Saccharomyces cerevisiae and the unicellular green alga Chlamydomonas reinhardtii. Here, we give an overview of the attempts made to transform mitochondria of mammals and plants and the possible reasons for their failure. This review briefly descri...

The green plant lineage is the second major multicellular expansion among the eukaryotes, arising from unicellular ancestors to produce the incredible diversity of morphologies and habitats observed today. In the unicellular ancestors, secretion of material through the endomembrane system was the major mechanism for interacting and shaping the external environment. In a multicellular organism, ...