Structural organization and expression analysis of the cdna encoding allatotropin in the cotton bollworm,Helicoverpa armigera

Abstract

The cDNA encoding allatotropin (AT), which stimulates juvenile hormone (JH) biosynthesis by the adult corpora allata (CA) of Lepidoptera, was cloned from Helicoverpa armigera (Har). Har-AT cDNA encodes a 135-amino acid polypeptide precursor containing a 13-amino acid AT sequence identical to Manduca sexta AT (Mas-AT). Three other H. armigera AT cDNAs encoding 172, 213, and 246 amino acids were also cloned. The four isoforms were produced by alternative splicing and termed Har-AT1, -AT2, -AT3, and -AT4, respectively. The basic organization of the Har-AT1 polypeptide precursor is similar to that of known ATs from other Lepidoptera with 80-97% identity at amino acid level. From the processing of the polypeptide precursor, three AT-like peptides named Har-ATL-I, -II, and -III were predicted. However, functions of the three AT-like peptides remain to be further elucidated. The evidence of Northern blots showed that a 0.7-kb Har-AT1 transcript is present in the brain and 0.7-kb Har-AT1 and 1.0-kb Har-AT4 transcripts are present in the abdominal ganglion (AG). Using quantitative RT-PCR, Har-AT mRNAs were detectable at much lower levels in other neural tissues, such as suboesophageal ganglion (SG) and thoracic ganglion (TG), but not in non-neural tissue, such as the epidermis, midgut, and fat body. We investigated the spatial and temporal expression of Har-AT gene in the central nervous system, and showed that expression patterns of four isoforms are distinct from each other. The results from immunocytochemistry showed that Har-AT transcript is located in the central nervous system, mainly in the brain and terminal abdominal ganglion (TAG). Thus, the AT gene products, besides affecting JH biosynthesis, might have broad influence on many biological processes in H. armigera.

Isolation and functional characterization of an allatotropin receptor from Manduca sexta

“…Alternative splicing of Manse-AT mRNAs is regulated in a stage-and tissue-specific manner and is predicted to yield a diverse set of peptide products that can vary in a dynamic manner during insect development (Horodyski et al, 2001;Lee et al, 2002). Similar alternative splicing of AT mRNAs and the existence of ATL peptides has been shown in several additional lepidopteran insects (Abdel-latief et al, 2003;Sheng et al, 2007;Yin et al, 2005).…”

“…Despite its widespread appearance in numerous insects, the AT sequence has not been identified in Drosophila melanogaster or other members of that genus (Hewes and Taghert, 2001;Vanden Broeck, 2001), or in the hymenopteran insects Apis mellifera (Hummon et al, 2006) or Nasonia vitripennis (Hauser et al, 2010). In some lepidopteran insects including M. sexta, multiple mRNAs that differ by alternative splicing are transcribed from the AT gene in a stage-and tissuespecific manner and predict the presence of peptides that are structurally related to Manse-AT [ATL peptides; (Abdel-latief et al, 2003;Horodyski et al, 2001;Sheng et al, 2007;Yin et al, 2005)], and whose biological activities overlap with those of Manse-AT (Lee et al, 2002).…”

Functional characterization of an allatotropin receptor expressed in the corpora allata of mosquitoes

“…The exceptions again are some species of Lepidoptera, where alternative splicing of a single AT mRNAs yields a diverse set of AT-like peptides (ATL) that can vary in a dynamic manner during insect development [1, 19, 26, 47, 59]. In M. sexta it was recently shown that these different ATL peptides present overlapping biological activities and act with different potencies through a common receptor [20].…”

Biochemical and molecular characterization of allatotropin and allatostatin from the Eri silkworm, Samia cynthia ricini

“…Similar to the AT genes in M. sexta (Taylor et al, 1996), S. frugiperda (Abdel-latief et al, 2003), and H. armigera (Yin et al, 2005), the Samcri-AT gene is expressed in at least three mRNA isoforms, termed Samcri-AT-1, -2, and -3 according to their ORF lengths. At first, Samcri-AT-2 (762 nt.)…”