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Size assessment and growth control: how adult size is determined in insects
Author(s) -
Mirth Christen Kerry,
Riddiford Lynn M.
Publication year - 2007
Publication title -
bioessays
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.175
H-Index - 184
eISSN - 1521-1878
pISSN - 0265-9247
DOI - 10.1002/bies.20552
Subject(s) - prothoracic gland , metamorphosis , biology , larva , drosophila melanogaster , ecdysone , nutrient sensing , insulin , microbiology and biotechnology , zoology , signal transduction , endocrinology , genetics , ecology , gene
Size control depends on both the regulation of growth rate and the control over when to stop growing. Studies of Drosophila melanogaster have shown that insulin and Target of Rapamycin (TOR) pathways play principal roles in controlling nutrition‐dependent growth rates. A TOR‐mediated nutrient sensor in the fat body detects nutrient availability, and regulates insulin signaling in peripheral tissues, which in turn controls larval growth rates. After larvae initiate metamorphosis, growth stops. For growth to stop at the correct time, larvae need to surpass a critical weight. Recently, it was found that the insulin‐dependent growth of the prothoracic gland is involved in assessing when critical weight has been reached. Furthermore, mutations in DHR4, a repressor of ecdysone signaling, reduce critical weight and adult size. Thus, the mechanisms that control growth rates converge on those assessing size to ensure that the larvae attain the appropriate size at metamorphosis. BioEssays 29:344–355, 2007. © 2007 Wiley Periodicals, Inc.