In situ hybridization analysis of the FMRFamide neuropeptide gene in Drosophila. I. Restricted expression in embryonic and larval stages

Abstract

We have used in situ hybridization techniques to describe the cellular distribution of transcripts from a Drosophila gene that encodes multiple FMRFamide-related neuropeptides. The Drosophila FMRFamide gene consists of two exons and is expressed predominantly as a approximately 1.7 kb RNA throughout postembryonic stages (Nambu et al., '88; Schneider and Taghert, '88, '90). We used exon-specific oligonucleotide probes to assay transcription in both embryonic and larval stages and found a pattern of hybridization signals that was restricted to the central nervous system and, within that tissue, was cell-specific. The pattern included 36 distinct signals distributed throughout both the brain and segmental nerve cord (ventral ganglion). These observations suggest that the cell-specific pattern of FMRFamide-like neuropeptide expression in the Drosophila CNS (White et al., '86; Taghert and Schneider, '90) is due to the restricted expression of specific gene transcripts. The results also indicate that, with few exceptions, all previously identified FMRFamide-immunoreactive neurons in Drosophila larvae express FMRFamide gene transcripts. The 36 hybridization regions of the CNS could be divided into three categories, based on their signal intensities (strong, moderate, and weak). The differences in intensity were reproducible and suggest that steady-state levels of specific neuropeptide RNA differ among individual neurons. The two exon-specific probes produced patterns that were indistinguishable both in pattern and in intensity. This result supports the previous conclusion that the one detectable FMRFamide transcript contains both exons (Schneider and Taghert, '90). A single identifiable signal was detected during embryogenesis (beginning at stage 16), but the mature complement of signals was not fully established until the final larval stages.

FMRFamide neuropeptides and neuropeptide-associated enzymes inDrosophila

“…More recently, we have observed transient, pupal stage-specific labeling of these same six abdominal neurons with antibody to peptide 3; in larval stages, these same cells express a truncated dFMRF-lacZ fusion in multiple transformant lines (J. Silber and Taghert, unpublished data). They do not label with dFMRF-amide RNA by in situ hybridization at any stage Schneider et al, 1991). These observations are consistent with the hypothesis that these neurons have the capacity to express dFMRFamide but normally express at low levels or are completely repressed.…”

“…In general, the results were consistent with the hypothesis that this transmitter system is restricted to a small subset of neurons in the CNS and is not normally found in non-neural tissues. Histochemical methods were developed to study transcript distribution in tissue sections Schneider et al, 1991) and in wholemount (Schneider et al, 1993a). In brief, the first method employed frozen sections of whole animals and 35 S-radiolabeled oligonucleotide probes (24 to 41 bases in length).…”

Transcriptional regulation of neuropeptide and peptide hormone expression by theDrosophila dimmedandcryptocephalgenes

“…In addition, several of the neuropeptide transcripts measured in this study are expressed exclusively or primarily in the CNS (e.g. Fmrf and Dms) (Nichols, 2003;Schneider et al, 1991). Larval genotypes were distinguished by scoring for yellow (y) or UBI-GFP.…”

Retrograde Gbb signaling through the Bmp type 2 receptor Wishful Thinking regulates systemic FMRFa expression inDrosophila

“…Drosophila FMRFa is expressed in many neurosecretory cells, including the Tv neurons that innervate a specialized tissue known as the neurohemal organ (NHO). As the NHO releases products into the hemolymph, FaRPs probably act systemically in a hormone-like fashion to regulate NMJ synaptic activity in vivo Schneider et al, 1991;Schneider et al, 1993a;Schneider et al, 1993b). Elucidating the mechanisms that control the peptidergic phenotype and activity of particular neurosecretory cells is therefore important for understanding how NMJ activity may be modulated by the neuroendocrine system.…”