Fig. 5.

Tai isoforms and their role in metamorphosis and oogenesis. a In hemimetabolous Blattella germanica, four isoforms are produced through the combination of IN-1 and IN-2 domains. Depletion of all four isoforms in nymphs led to 100% mortality. Upon JH induction and Met binding, only BgTai-A and BgTai-B isoforms mediated the anti-metamorphic action of JH [49]. b Five splicing variants of Tai are found in holometabolous Bactrocera dorsalis. Specific knockdown of BdTai-E caused precocious metamorphosis, similar to that resulted from simultaneous depletion of all five isoforms [168]. c Two isoforms, LmTai-A and LmTai-B are identified in Locusta migratoria. Knockdown of both LmTai isoforms or LmTai-A alone but not LmTai-B resulted in defective phenotypes of oogenesis. Both isoforms dimerized with Met in the presence of JH and induced Kr-h1 transcription, but LmTai-A mediated a stronger transactivation than LmTai-B [44]. d In Aedes aegypti, the combinations of exon 12 (matching to IN-1) and exon 13 (matching to IN-2) produce 4 isoforms. JH acted via the RTK/PI3K/Akt and SRSF pathway to induce the production of AaTai-A and AaTai-B, which potentiated the 20E-EcR/USP transactivation and stimulated female reproduction [48]