Aging and its relation to cell growth and differentiation in Drosophila imaginal discs: developmental response to growth restricting conditions.

Abstract

The development of Drosophila organ discs can be arrested by culturing them in adult male flies. These aged discs lose some of their differentiation competence and form incomplete imaginal structures. The more advanced the aging, the greater the loss of competence. Discs made to differentiate prematurely show deficiencies similar to aged discs. The age-induced defects can be repaired in a larval milieu. Special hormonal conditions, but not cell multiplication, are apparently involved in the recovery process. The action of hormones as controlling mechanisms in the growth and differentiation of Drosophila development has been well established. Moreover, it has been known for a long time that the imaginal discs, i.e., the anlagen of the future adult organs, metamorphose and differentiate under the influence of a hormone released by the ring gland at the end of larval life; they finally form the various cuticular structures that make up the adult integument (1). In the interaction between hormone and tissues, two parameters are of particular significance: the hormone titer and the readiness of the target tissues to respond to the hormonal demands in a characteristic manner. Different developmental stages of a tissue can respond differently to the same hormonal environment. For instance, very young imaginal discs will continue to grow in the humoral milieu of a late larva, whereas the hormones of a larva of the same age will induce imaginal differentiation in older discs. Discs of intermediate age transplanted prematurely into metamorphosing hosts may exhibit partial imaginal differentiation (2). To acquire competence to metamorphose a young disc need not undergo its development solely in a larval environment, even though this is of course its norm. By appropriate experimental manipulation, a disc can become competent by developing in a pupal and/or pharate adult host. Mindek (3) transplanted incompetent eye-antenna discs from newly hatched larvae into older larvae ready to pupate. After metamorphosis of the host the discs were still undifferentiated, thus showing their incompetence to respond to the metamorphosis factors. Yet they had grown in their new host environment from pupation to emergence of the fly, to the size of a disc equivalent to an older larval stage. Such discs were transplanted for a second time into larvae ready to pupate. They were dissected after the emergence of the second host and found now to have differentiated to imaginal completion, exhibiting all their organ specific adult structures.

Farnesoid secretions of dipteran ring glands: What we do know and what we can know

“…Toward testing these hypotheses, Schweizer and Bodenstein (1975) endocrinologically confirmed that fully grown (proliferated) genital discs taken from larvae 4 h prior to pupariation, upon transplantation into back into a mature (same age) larval host, would then proceed to differentiate during the subsequent host pupariation through adult eclosion. If, instead, the fully proliferated disc was first cultured in an adult male host, the disc lost its competence to differentiate when then transplanted into mature 3rd instar larva.…”

Regeneration and transdetermination: The role of wingless and its regulation

“…One reason may be that the cells at the dorsal cut rarely contribute to the regenerate (Abbott et al, 1981), indicating that they are not participating in the proliferating blastema. The induction of proliferation however is a prerequisite for regeneration and TD (Schubiger, 1973; Schweizer and Bodenstein, 1975). In addition WG and Dpp must interact for TD to occur (Maves and Schubiger, 1998), but at the dorsal cut wg is not expressed.…”

Transdetermination in Drosophila imaginal discs: a model for understanding pluripotency and selector gene maintenance

“…Clonal analyses reveal that imaginal disc regeneration proceeds from blastema cells [28,31] and that transdetermined structures derive from, and are clonally related to, the newly regenerated tissue [23][24][25]. Transdetermination requires cell division because when disc fragments are cultured in conditions in which cell division is inhibited, no transdetermination is observed [33,34]. Vertebrate limb regeneration also proceeds through the formation of a blastema, in which cells undergo dedifferentiation and proliferation (reviewed in [1,2]).…”