An Abnormality in the Life Cycle of Tokophrya infusionum

Abstract

SYNOPSIS. Tokophrya infusionum reproduces by endogenous budding, forming a ciliated embryo within a brood pouch. The embryo is released to the outside medium, where it swims for some time, then undergoes metamorphosis by the formation of a disk, stalk, and tentacles. In one of the clones (E22), 1–2% of the adults display abnormalities during reproduction. In some of the abnormal adults, the embryo is retained inside a greatly enlarged brood pouch and undergoes metamorphosis within the parent; in others, the embryo is not formed, and only a large empty brood pouch appears. Attempts to establish a separate clone composed only of abnormal organisms were unsuccessful, and led to the conclusion that all members of clone E22 are potentially abnormal. Experiments were performed to increase the percentage of abnormal organisms; it was found that overfeeding is one of the factors favoring abnormal reproduction. Physiological and genetic explanations of the abnormality are proposed and discussed.

Life History Responses to Resource Variation in a Sessile Predator, The Ciliate Protozoan Tokophrya Lemnarum Stein

“…Tokophrya lemnarum and other suctorians, i.e., T. infusionum (Millecchia and Rudzinska 1968), Solenophrya micraster (Hull 1954), and Podophrya collini (Hull 1956), reproduce only after food ingestion, and each bud receives a portion of the parental food vacuoles. Tokophrya lemnarum and other suctorians, i.e., T. infusionum (Millecchia and Rudzinska 1968), Solenophrya micraster (Hull 1954), and Podophrya collini (Hull 1956), reproduce only after food ingestion, and each bud receives a portion of the parental food vacuoles.…”

“…In a series of papers, Rudzinska (1951, 1952, 1953, 1961, 1962, and Millecchia and Rudzinska 1968 attributed this relationship to overfeeding stress. In a series of papers, Rudzinska (1951, 1952, 1953, 1961, 1962, and Millecchia and Rudzinska 1968 attributed this relationship to overfeeding stress.…”

“…The negative feedback between food stress and reproduction is probably an adaptation toward increasing bud, rather than adult, survival. Tokophrya lemnarum and other suctorians, i.e., T. infusionum (Millecchia and Rudzinska 1968), Solenophrya micraster (Hull 1954), and Podophrya collini (Hull 1956), reproduce only after food ingestion, and each bud receives a portion of the parental food vacuoles. These food vacuoles supply the nonfeeding bud with nutrients for its period of active movement and metamorphosis.…”

“…An inverse relationship exists between life span and fecundity-food level in T. lemnarum. In a series of papers, Rudzinska (1951, 1952, 1953, 1961, 1962, and Millecchia and Rudzinska 1968 attributed this relationship to overfeeding stress. Greatly overfed individuals of T. infusionum ceased reproduction and had shortened life spans.…”