Identification and expression of capa gene in the fire ant, Solenopsis invicta

PLoS One. 2014 Apr 9;9(4):e94274. doi: 10.1371/journal.pone.0094274. eCollection 2014.

Abstract

Recent genome analyses suggested the absence of a number of neuropeptide genes in ants. One of the apparently missing genes was the capa gene. Capa gene expression in insects is typically associated with the neuroendocrine system of abdominal ganglia; mature CAPA peptides are known to regulate diuresis and visceral muscle contraction. The apparent absence of the capa gene raised questions about possible compensation of these functions. In this study, we re-examined this controversial issue and searched for a potentially unrecognized capa gene in the fire ant, Solenopsis invicta. We employed a combination of data mining and a traditional PCR-based strategy using degenerate primers designed from conserved amino acid sequences of insect capa genes. Our findings demonstrate that ants possess and express a capa gene. As shown by MALDI-TOF mass spectrometry, processed products of the S. invicta capa gene include three CAPA periviscerokinins and low amounts of a pyrokinin which does not have the C-terminal WFGPRLa motif typical of CAPA pyrokinins in other insects. The capa gene was found with two alternative transcripts in the CNS. Within the ventral nerve cord, two capa neurons were immunostained in abdominal neuromeres 2-5, respectively, and projected into ventrally located abdominal perisympathetic organs (PSOs), which are the major hormone release sites of abdominal ganglia. The ventral location of these PSOs is a characteristic feature and was also found in another ant, Atta sexdens.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternative Splicing / genetics
  • Amino Acid Sequence
  • Animals
  • Ants / genetics*
  • Base Sequence
  • Female
  • Ganglia, Invertebrate / cytology
  • Ganglia, Invertebrate / metabolism
  • Gene Expression Profiling
  • Gene Expression Regulation*
  • Genes, Insect*
  • Insect Proteins / chemistry
  • Insect Proteins / genetics
  • Insect Proteins / metabolism
  • Molecular Sequence Data
  • Neurons / metabolism
  • Peptides / chemistry
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • Transcription, Genetic

Substances

  • Insect Proteins
  • Peptides
  • RNA, Messenger

Grants and funding

The authors acknowledge the financial assistance of the Deutsche Forschungsgemeinschaft (Predel 595/6-1, 2; 766/9-1) and Luxemburg Foundation (to RK). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.