Search bioRxiv⌕ Search

Biology subjects

Shirangi, T. R.

Publications and source records attributed to Shirangi, T. R..

6 recordsLinked to original sources

Cis-regulatory fragments from the dissatisfaction gene identify novel mating behavior neurons in female Drosophila

During Drosophila courtship, males chase and sing to females, while females perform abdominal behaviors to indicate their willingness to mate. The nerve cord circuits in females that produce their abdominal behaviors are poorly characterized. We recently identified an anatomically diverse population of abdominal interneurons, the DDAG neurons, which express the Tlx-like nuclear receptor dissatisfaction (dsf) and influence several female mating behaviors. Here, we searched the dsf locus for cis-regulatory enhancer fragments that regulate its spatial expression in the adult and larval central nervous system. We found several enhancers, most located within two introns, that drove reporter expression in subsets of dsf-expressing neurons throughout the brain and nerve cord. Using one of these enhancers, we genetically isolated a single subtype of female-specific DDAG local interneurons. Optogenetic activation of these neurons triggered vaginal plate opening in both unmated and mated females, a behavior used by Drosophila females to signal receptivity to courting males. Our findings offer new reagents to target dsf-expressing cells and new insights into the neural substrates in Drosophila females that express their mating decisions during courtship.

neuroscience↗

An α-1,3-fucosyltransferase influences thermal nocifensive escape behaviors in Drosophila larvae

When exposed to noxious thermal or mechanical stimuli, Drosophila melanogaster larvae will aZempt to escape by performing a stereotypical nocifensive rolling behavior. Here, we report the identification of a mutation in Drosophila that specifically alters the thermal nocifensive escape behaviors of larvae. We provide genetic, molecular, and histological evidence that this mutation maps to the FucTA gene, which encodes an -1,3-fucosyltransferase. Our results suggest that fucosylation is important for the thermal nociception rolling behavior of Drosophila larvae.

genetics↗

Hierarchical diversification of instinctual behavior neurons by lineage, birth order, and sex

Brain regions that regulate motivated behaviors, including the vertebrate hypothalamus and arthropod cerebrum, house bespoke neural circuits dedicated to perceptual and internal regulation of many behavioral states1,2. These circuits are built to purpose from complex sets of cell types whose patterning has been challenging to elucidate. Here, we developed methods in Drosophila melanogaster to embed well-studied neurons that regulate mating in the transcriptional contexts of the neuronal lineages that generate them3-5. By comparing transcription within and between lineages, we identified a large set of transcription factors expressed in complex combinations that delineate cerebral hemilineages - classes of postmitotic neurons born from the same stem cell and sharing Notch status6,7. Hemilineages comprise the major anatomic classes in the cerebrum8-10 and these transcription factors are required to generate their gross features. We show that subtypes of the same hemilineage can provide a common computational module to circuits regulating different drives, and identify an orthogonal set of transcription factors that stratify hemilineage subtypes of differing birth order. Our findings suggest that distinct sets of transcription factors operate in a hierarchical system to build, diversify, and sexually differentiate lineally-related neurons that compose motivated behaviors circuits. By linking developmental patterning to separable transcriptional axes that produce gross versus fine aspects of information flow, we provide a logical framework for cerebral control of diverse drives.

neuroscience↗

Developmental remodeling repurposes larval neurons for sexual behaviors in adult Drosophila

Most larval neurons in Drosophila are repurposed during metamorphosis for functions in adult life, but their contribution to the neural circuits for sexually dimorphic behaviors is unknown. Here, we identify two interneurons in the nerve cord of adult Drosophila females that control ovipositor extrusion, a courtship rejection behavior performed by mated females. We show that these two neurons are present in the nerve cord of larvae as mature, sexually monomorphic interneurons. During pupal development, they acquire the expression of the sexual differentiation gene, doublesex, undergo doublesex-dependent programmed cell death in males, and are remodeled in females for functions in female mating behavior. Our results demonstrate that the neural circuits for courtship in Drosophila are built in part using neurons that are sexually reprogrammed from former sex-shared activities in larval life.

neuroscience↗

Combined in situ hybridization chain reaction and immunostaining to visualize gene expression in whole-mount Drosophila central nervous systems

Methods to visualize gene expression in the Drosophila central nervous system are important in fly neurogenetic studies. In this chapter, we describe a detailed protocol that sequentially combines in situ hybridization chain reaction (HCR) and immunostaining to detect mRNA and protein expression in whole-mount Drosophila larval and adult central nervous systems. We demonstrate the application of in situ HCR in comparisons of nervous system gene expression between Drosophila species, and in the validation of single-cell RNA-Seq results in the fly nervous system. Our protocol provides a simple, robust, multiplexable, and relatively affordable means to quantitatively visualize gene expression in the nervous system of flies, facilitating its general use in fly neurogenetic studies.

neuroscience↗

Regulation of sexually dimorphic abdominal courtship behaviors in Drosophila by the Tlx/tailless-like nuclear receptor, Dissatisfaction

Sexually dimorphic courtship behaviors in Drosophila melanogaster develop from the activity of the sexual differentiation genes, doublesex (dsx) and fruitless (fru), functioning with other regulatory factors that have received little attention. The dissatisfaction gene (dsf) encodes an orphan nuclear receptor homologous to vertebrate Tlx and Drosophila tailless that is critical for the development of several aspects of female- and male-specific sexual behaviors. Here, we report the pattern of dsf expression in the central nervous system and show that the activity of sexually dimorphic abdominal interneurons that co-express dsf and dsx is necessary and sufficient for vaginal plate opening in virgin females, ovipositor extrusion in mated females, and abdominal curling in males during courtship. We find that dsf activity results in different neuroanatomical outcomes in females and males, promoting and suppressing, respectively, female development and function of these neurons depending upon the sexual state of dsx expression. We posit that dsf and dsx interact to specify sex differences in the neural circuitry for dimorphic abdominal behaviors.

neuroscience↗