Month: September 2022

LAST ACT. "Semelparous animals show a similar pattern. Among vertebrates, the best studied examples of rapid senescence and death following semelparous reproduction are in fishes and marsupial mammals. Anadromous Pacific salmon (Oncorhynchus spp.), and catadromous eels (Anguilla spp.) and lampreys (Petromyzontidae) die shortly after spawning." View in LinkedIn

DEATH SIGNAL. "Males of several small marsupials die shortly after mating. Remarkably, the proximate molecular mechanisms of decline and death in all these distantly related vertebrates seem to be similar, with corticosteroid stress hormones playing the central role." View in LinkedIn

NO LAST REQUESTS. "Among invertebrates, cases of death following semelparous reproduction that clearly seem to be coded into the genome (and thus “programmed”) include the many insects in which adults entirely lack mouthparts or are otherwise incapable of feeding." View in LinkedIn

LAST FLING. "In some cephalopod molluscs, rapid senescence and death follow spawning (squids) or brooding (octopuses). For example, in Octopus hummelincki, brooding females alter and reduce feeding behavior and die shortly after their eggs hatch. These traits are influenced by endocrine secretions from the optic gland." View in LinkedIn

EXECUTIONER'S REPRIEVE. "In both plants and animals, life span can be is extended by experimental manipulations of physiology and/or reproduction, indicating that senescence is not the inevitable outcome of physical constraints." View in LinkedIn

GONADECTOMY EXTENSION. "For example, lifespan of semelparous annual plants can often be artificially extended by removing reproductive structures. Optic gland removal in O. hummelincki causes cessation of brooding, reinstates normal feeding behavior, and extends life. In fishes, removal of the gonads (Pacific salmon, lampreys) or of the pituitary gland (lampreys) and prevention of mating (eels) can substantially increase life span." View in LinkedIn

REFERENCE FOR TODAY: Are Internal, Death-Promoting Mechanisms Ever Adaptive?" "John W Pepper, Deborah E Shelton, Armin Rashidi, and Pierre M Duran. (This reference refuses to post normally on LI). View in LinkedIn

INTERNAL DEATH CLOCK. "Similarly in small marsupials, castration or prevention of mating can increase male life span up to that of females. These experiments indicate that rapid senescence and death following reproduction in at least some semelparous animals are genetically “programmed” and internally controlled." View in LinkedIn

SPARING THE PROLIFIC. "Iteroparous organisms have multiple reproductive episodes during the life cycle, as opposed to a solitary event. In these species, senescence leading to death is less abrupt and dramatic, but is ubiquitous nonetheless. General explanations for organismal senescence are varied and contentious, and the idea that iteroparous senescence is “programmed” is not the majority view." View in LinkedIn

GENETIC SENESCENCE. "There is substantial evidence for genetic control of senescence in some iteroparous animals, indicating that senescence is at least sometimes “programmed” (in the inclusive sense) and highlighting the question of the relationship between aging “programs” and selection. For example, in Drosophila melanogaster, selective breeding and other studies demonstrated a genetic, heritable component to senescence." View in LinkedIn