The Evolution of Death: Why We Are Living Longer

Glossary

Glossary AC: adult cache: cells in adult expanding tissue. actual or functional stem cells: the traditional stem cells of steady-state tissues. AIDS: acquired immune deficiency syndromes. allele: a particular gene or locus on a chromosome. allometry: the correlation of growth of a part to the growth of a whole organism. APCs: antigen presenting cells. aptness: fitness; suitable integration of structure and function. AR: adult reserve: cells in adult static and steady-state tissue; cognate of stem cell. Archaea: one of the three domains of cellular life assigned originally on the basis of ribosomal RNAs; see prokaryote. autopoiesis: immanent, self-regulating, or emergent abilities of organisms for development and maintenance. Bacteria: one of the three domains of cellular life, including unicellular bacteria, biofilms, and blue-green bacteria, assigned currently on the basis of ribosomal RNAs; see prokaryote. bell-shaped curve: see normal distribution. bFGF: basic fibroblast growth factor. blastocyst: early stage in development of mammals following cleavage and prior to implantation; aka preembryo. blastomeres: cells formed by cleavage of the zygote and by further division of blastomeres prior to cell movement, rearrangement, and embryogenesis. BM: bone marrow. cache cells: differentiated chief cells of expanding tissues that retain capacity for proliferation . Caenorhabditis elegans (C. elegans): a species of roundworms considered a model system for various kinds of cell and integrative research including aging. chromatin: combination of DNA, and proteins within nucleus; strands of DNA wound around histones in nucleosomes. 197 chromosomes: [colored bodies] thread- or rod-like bodies that split and are equally distributed to the two cells formed in eukaryotes during cell division; linear nuclear bearers of genes and other DNA such as “junk” DNA and telomeres; also circular DNA of prokaryotes. cleavage: division of the zygote and blastomeres. cohort: all the members of a group born at the same time (typically a year for human beings; a day for fruit flies). conjugation: sexual coupling of protozoans during which nuclei are exchanged and a new generation of exconjugants is spawned. Darwinian evolution, theory of, or Darwinism: accounts for differences among species through the accumulation of small, quantitative variation; gradual change among species due to the accumulation of small, hereditary differences; differential rates of breeding among organisms with small, hereditary differences. dedifferentiate: the loss of a cell’s typical identity, typically associated with a change in a cell’s determination. deepithelialize: when an epithelial tissue gives rise to freely moving, independent cells. determination: loosely, an irreversible phase in the chain of events leading to differentiation . differentiate: a cell’s acquisition of its final morphology; the appearance and accumulation of a cell’s distinctive cellular content, typically intermediate filaments. diploid: eukaryotic cell containing dual, homologous nuclear chromosomes. DNA: deoxyribonucleic acid; genetic material of cellular life. Drosophila melanogaster (Drosophila): a species of flies usually called fruit flies and frequently considered a model system for aging research. EC: embryonic carcinoma. EG: embryonic germ; pluripotent cells derived from germinal ridge of fetus and raised in tissue culture. embryo transfer: see in vitro fertilization. endopterygote (holometabolous): insects with complete metamorphosis in pupa; insect develops wings during metamorphosis in pupa. environment: everything that impacts on an organism’s ability to live and reproduce, from its abode, availability of resources, and the weather. epiblast: one (unilaminar) or two (bilaminar) cell layers (also known as the embryonal plate) formed in the blastocyst from the inner cell mass and giving rise to the embryonic germ layers at gastrulation. epigenetic: the host of controls, including gene silencing through DNA methylation, with their greatest roles in modulating patterns of phenotypic determination, nonMendelian hereditary effects, and cytoplasmic influences on traits. 198 GLOSSARY epistasis: interactions among genes, usually promoting some aspect of fitness in the phenotype. EPL: early pregnancy loss. ES: embryonic stem; pluripotent cells derived from epiblast of embryo and raised in tissue culture. Escherichia coli (E. coli): model bacterium used in biotech industry; coliform; Gramnegative ; enteric. eukaryote: one of the three domains of cellular life; unicellular or multicellular organism whose cells are compartmentalized, containing membranous, and non-membranous organelles, a cytoskeleton, cytosol, and one or more nuclei bearing hereditary material in the form of nuclear genes; currently assigned on the basis of ribosomal RNAs. exopterygote (hemimetabolous): insects molting through several larval stages without a pupa; insects developing wings during larval stages. FACS: fluorescence-activated cell sorting. founder cells: embryonic blast or stem cells in C. elegans embryos; also the epiblast of mammals. fractal: structure with similar patterns recurring on different...