Dimorphic Ovary Differentiation in Honeybee (Apis mellifera) Larvae Involves Caste-Specific Expression of Homologs of Ark and Buffy Cell Death Genes

Author(s)

Dallacqua, Rodrigo Pires ^[1] ; Gentile Bitondi, Marcia Maria ^[2]

Affiliation

^[1] Univ Fed Mato Grosso do Sul, Setor Biol Geral, Mato Grosso - Brazil

^[2] Univ Sao Paulo, Fac Filosof, Dept Biol, BR-14049 Ribeirao Preto, SP - Brazil

• Document type: Journal article
• Source: PLoS One; v. 9, n. 5 MAY 20 2014.
• Web of Science Citations: 11

Abstract

The establishment of the number of repeated structural units, the ovarioles, in the ovaries is one of the critical events that shape caste polyphenism in social insects. In early postembryonic development, honeybee (Apis mellifera) larvae have a pair of ovaries, each one consisting of almost two hundred ovariole primordia. While practically all these ovarioles continue developing in queen-destined larvae, they undergo massive programmed cell death (PCD) in worker-destined larvae. So as to gain insight into the molecular basis of this fundamental process in caste differentiation we used quantitative PCR (qPCR) and fluorescent in situ hybridization (FISH) to investigate the expression of the Amark and Ambuffy genes in the ovaries of the two honeybee castes throughout the fifth larval instar. These are the homologs of ark and buffy Drosophila melanogaster genes, respectively, involved in activating and inhibiting PCD. Caste-specific expression patterns were found during this time-window defining ovariole number. Amark transcript levels were increased when ovariole resorption was intensified in workers, but remained at low levels in queen ovaries. The transcripts were mainly localized at the apical end of all the worker ovarioles, but appeared in only a few queen ovarioles, thus strongly suggesting a function in mediating massive ovariolar cell death in worker larvae. Ambuffy was mainly expressed in the peritoneal sheath cells covering each ovariole. The levels of Ambuffy transcripts increased earlier in the developing ovaries of queens than in workers. Consistent with a protective role against cell death, Ambuffy transcripts were localized in practically all queen ovarioles, but only in few worker ovarioles. The results are indicative of a functional relationship between the expression of evolutionary conserved cell death genes and the morphological events leading to caste-specific ovary differentiation in a social insect. (AU)

• FAPESP's process: 11/03171-5 - Causal analysis of Apis mellifera development: regulatory genes and hierachical networks of gene expression in the specification of tissue and organs
• Grantee: Zilá Luz Paulino Simões
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 09/15772-3 - Caste-specific molecular determinants of ovary development in the honey bee, Apis mellifera.
• Grantee: Rodrigo Pires Dallacqua
• Support Opportunities: Scholarships in Brazil - Post-Doctoral