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Title: Expression analysis of vitellogenins in the workers of the red imported fire ant ( Solenopsis invicta )

Vitellogenin has been proposed to regulate division of labor and social organization in social insects. The red imported fire ant (Solenopsis invicta) harbors four distinct, adjacent vitellogenin genes (Vg1, Vg2, Vg3, and Vg4). Contrary to honey bees that have a single Vg ortholog as well as potentially fertile nurses, and to other ant species that lay trophic eggs,S. invictaworkers completely lack ovaries or the ability to lay eggs. This provides a unique model to investigate whether Vg duplication inS. invictawas followed by subfunctionalization to acquire non-reproductive functions and whether Vg was co-opted to regulate behavior within the worker caste. To investigate these questions, we compared the expression patterns ofS. invictaVg genes among workers from different morphological subcastes or performing different tasks. RT-qPCRs revealed higher relative expression of Vg1 in major workers compared to both medium and minor workers, and of Vg2 in major workers when compared to minor workers. Relative expression of Vg1 was also higher in carbohydrate foragers when compared to nurses and protein foragers. By contrast, the level of expression of Vg2, Vg3, and Vg4 were not significantly different among the workers performing the specific tasks. Additionally, we analyzed the relationship between the expression of the Vg genes and S-hydroprene, a juvenile hormone analog. No changes in Vg expression were recorded in workers 12 h after application of the analog. Our results suggest that inS. invictathe Vg gene underwent subfunctionalization after duplication to new functions based on the expression bias observed in these data. This may suggest an alternative and still unknown function for Vg in the workers that needs to be investigated further.

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NSF-PAR ID:
10154996
Author(s) / Creator(s):
;
Publisher / Repository:
PeerJ
Date Published:
Journal Name:
PeerJ
Volume:
6
ISSN:
2167-8359
Page Range / eLocation ID:
Article No. e4875
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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