Abstract
ABSTRACTDuring development, HOX genes play critical roles in the establishment of segmental differences. In the Drosophila central nervous system, these differences are manifested in the number and type of neurons generated by each neuroblast in each segment. HOX genes can act either in neuroblasts or in postmitotic cells, and either early or late in a lineage. Additionally, they can be continuously required during development or just at a specific stage. Moreover, these features are generally segment-specific. Lately, it has been shown that contrary to what happens in other tissues, where HOX genes define domains of expression, these genes are expressed in individual cells as part of the combinatorial codes involved in cell type specification. In this report we analyse the role of the Bithorax-complex genes – Ultrabithorax, abdominal-A and Abdominal-B – in sculpting the pattern of crustacean cardioactive peptide (CCAP)-expressing neurons. These neurons are widespread in invertebrates, express CCAP, Bursicon and MIP neuropeptides and play major roles in controlling ecdysis. There are two types of CCAP neuron: interneurons and efferent neurons. Our results indicate that Ultrabithorax and Abdominal-A are not necessary for specification of the CCAP-interneurons, but are absolutely required to prevent the death by apoptosis of the CCAP-efferent neurons. Furthermore, Abdominal-B controls by repression the temporal onset of neuropeptide expression in a subset of CCAP-efferent neurons, and a peak of ecdysone hormone at the end of larval life counteracts this repression. Thus, Bithorax complex genes control the developmental appearance of these neuropeptides both temporally and spatially.
Highlights
Neuropeptides are small proteins, widespread in multicellular organisms, which act as chemical signals within the endocrine system
Requirements of Ubx and Abd-A in the specification of the crustacean cardioactive peptide (CCAP)-ENs Because of the segmental differences observed in the pattern of CCAP-ENs, we wondered whether HOX genes played a role in controlling the specification of CCAP-ENs
We obtained the same results when we stained for CCAP. These results suggested that Ubx is required to specify the CCAP-EN fate in segments T3–A4, and that in the absence of Ubx, Abd-A drives the specification of the ENs in segments A2−4
Summary
Neuropeptides are small proteins, widespread in multicellular organisms, which act as chemical signals within the endocrine system. *Present address: Department of Life Sciences, Imperial College London, Sir Ernst Chain Building, South Kensington Campus, London SW7 2AZ, UK. In Drosophila melanogaster, about 42 genes that encode precursors of neuropeptides, peptide hormones or protein hormones have been identified (Nässel and Winther, 2010). They are expressed in a stereotyped pattern of neurons and neurosecretory cells, mostly in the CNS. These are usually large cells identifiable by immunostaining (Park et al, 2008)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
