RNA interference‐mediated functional characterization of aquaporin genes in Tribolium castaneum

Abstract

An obvious challenge faced by most terrestrial insects is maintaining water homeostasis in an arid environment. Current research suggests aquaporins may be evolved to meet the challenge. However, up to now, this suggestion has not been verified in any insect that feeds upon solid food with mandibulate mouthparts. In the present paper, nine putative aquaporin genes [Tribolium castaneum big brain, T. castaneum Drosophila integral protein (TcDrip), T. castaneum Pyrocoelia rufa integral protein (TcPrip), T. castaneum aquaporin 12-like, T. castaneum entomoglyceroporin 1 (TcEglp1), TcEglp2, TcEglp3, TcEglp4 and TcEglp5] were identified in T. castaneum. The transcripts of the nine genes were easily detectable in the foregut, midgut, hindgut-Malpighian tubule complex, fat body and carcass (except gut and fat body). Amongst them TcDrip, TcPrip, TcEglp1, TcEglp3 and TcEglp5 were highly transcribed in the hindgut-Malpighian tubule complex; TcEglp4 was abundantly expressed in both the fat body and hindgut-Malpighian tubule complex. RNA interference (RNAi)-mediated knockdown of TcEglp3 caused a grey larval cuticle, in contrast to a smooth and bright cuticle in control larvae. Approximately 40% of the TcEglp3 RNAi larvae had their hindguts protruding from the anus; their fresh wet faeces were attached to the hindgut. Another 20% of these treated larvae did not defaecate normally; wet brown faeces were adhered to the anal area. As a result, the larval growth was inhibited and about 60% larval lethality occurred. Silencing of TcEglp4 or TcDrip exhibited similar but weaker defective phenotypes as those of the TcEglp3-silenced larvae. Therefore, Eglp3, Eglp4 and Drip may contribute to the conductance of water in the alimentary canal and Malpighian tubules in T. castaneum.

An aquaporin mediates cell shape change required for cellular immunity in the beet armyworm, Spodoptera exigua

“…This suggests that RNAi treatment can increase the severity, resulting in detrimental effect. Similar detriment effects of RNAi against AQP genes have been reported in Tribolium castaneum that expresses nine AQPs 67 . Knockdown of TcEglp3 , TcEglp4 , or TcDRIP killed ~20% to ~60% of larvae before pupation 67 .…”

“…Because most AQPs of T . castaneum are expressed in HG and MT, the lethal effect of RNAi treatment can be explained by malfunctioning of excretory system 67 . This suggests that the high mortality observed in S .…”

Response of Tribolium castaneum to dietary mannitol, with remarks on its possible nutritive effects

“…Several aquaporin genes were expressed in the gut in T . castaneum [ 30 ], possibly allowing the aquaporin to transport mannitol from the gut cavity to the hemolymph. After being fed mannitol the hemolymph of T .…”

Sob gene is critical to wing development in Bombyx mori and Tribolium castaneum

“…S3). The targeted region of the Tcsob gene was further Basic Local Alignment Search Tool Nucleotide (BLASTN) searched against the T. castaneum genome to identify possible off-target sequences that had an identical match of 21 bp or more (Yao et al, 2018). The Tcsob fragment and EGFP fragment were amplified by PCR using specific primers conjugated with the T7 RNA polymerase recognition promoter sequence at the 5 end (primers are listed in Table S1).…”