In addition to the visible complexity expressed in the morphogenesis of multicellular organisms, two levels of microscopic complexity may be discerned within every living cell. The first level is related to covalently bonded structures, namely molecules. The second level has to do with the generation of non-covalent molecular assemblies. Origin of life research has largely focused on the first ...

Immunofluorescent staining of the prespore cells of the cellular slime mould Dictyostelium discoideum was carried out using a heterologous spore antibody. The highly specific staining of the prespore vesicles (PSVs) within the prespore cells enabled quantitative determinations to be made of the rate and extent of development of these cells throughout the life cycle. The results showed that PSVs...

Despite the protracted history of life on earth spanning well over 3.8 Ga, fossil record of the Precambrian (>543 Ma) largely documents only microscopic life. The mostly simple Precambrian life forms were followed by a sudden explosive radiation of multicellular animals at the turn of the Cambrian period (543-490 Ma) between 530 and 520 Ma ago, when almost two-thirds of the animal phyla make th...

The advent of multicellularity was a watershed event in the history of life, yet the transition from unicellularity to multicellularity is not well understood. Multicellularity opens up opportunities for innovations in intercellular communication, cooperation, and specialization, which can provide selective advantages under certain ecological conditions. The unicellular alga Chlamydomonas reinh...

Choanoflagellates are the closest living relative of animals (Alegado, 2014; King, 2015; King 2016; Rokas, 2008). This has been confirmed through multiple lines of phylogenetic analyses, comparative genomics, and similarities in cell biology (Alegado, 2014; King, 2001). Previous studies of the choanoflagellate Salpingoeca rosetta suggest that bacteria may have played an important role in the ea...

Aging is a degenerative process characterized by a progressive deterioration of cellular components and organelles resulting in mortality. The budding yeast Saccharomyces cerevisiae has been used extensively to study the biology of aging, and several determinants of yeast longevity have been shown to be conserved in multicellular eukaryotes, including worms, flies, and mice. Due to the lack of ...

The history of life is punctuated by evolutionary transitions which engender emergence of new levels of biological organization that involves selection acting at increasingly complex ensembles of biological entities. Major evolutionary transitions include the origin of prokaryotic and then eukaryotic cells, multicellular organisms and eusocial animals. All or nearly all cellular life forms are ...

Reproduction is a defining feature of living systems. To reproduce, aggregates of biological units (e.g., multicellular organisms or colonial bacteria) must fragment into smaller parts. Fragmentation modes in nature range from binary fission in bacteria to collective-level fragmentation and the production of unicellular propagules in multicellular organisms. Despite this apparent ubiquity, the ...