Biology subjects

Steck, K.

Publications and source records attributed to Steck, K..

4 recordsLinked to original sources

bioRxiv2026

Abdominal-B regulates the male seminal fluid transferome and new female fecundity factors required for sperm sex peptide binding

Seminal fluid proteins determine reproductive success in a wide range of animals. In the Drosophila male accessory gland, seminal fluid is mainly produced by two cell types, a vast majority of main cells and a small number of secondary cells that possess a specialized secretory apparatus with unusually enlarged dense core granule vesicles. Loss of Abdominal-B expression from secondary cells in the enhancer mutant iab-6cocu disrupts their transcriptional and secretory identity. Consequently, mutant males fail to induce the long-term post-mating response in females, which is characterized by a loss of receptivity and sustained egg laying. Here, we determine how secondary cells shape the seminal transferome and the female response by assessing iab-6cocu male accessory gland and female mate reproductive tract proteomes. We find downregulation of seminal fluid proteins that constitute a signaling network that enables sperm binding and the sustained action of the key regulator Sex peptide and identify two new Sex peptide network proteins crucial for female fecundity, Cornutus (CG1701) and Hanrej (CG42564). Cornutus is required for mating dependent dense core granule vesicle release, providing a link between the products of these compartments and the female long-term post-mating response. Our data highlights the importance of secondary cell signaling and secretion for overall seminal fluid composition and Sex peptide network function as well as the interdependence of main and secondary cells and their secretory products, advancing the general understanding of how seminal fluid signaling pathways modulate female physiology, sperm use and offspring production.

physiology↗

bioRxiv2023

A competitive disinhibitory network for robust optic flow processing in Drosophila

Many animals rely on optic flow for navigation, using differences in eye image velocity to detect deviations from their intended direction of travel. However, asymmetries in image velocity between the eyes are often overshadowed by strong, symmetric translational optic flow during navigation. Yet, the brain efficiently extracts these asymmetries for course control. While optic flow sensitive-neurons have been found in many animal species, far less is known about the postsynaptic circuits that support such robust optic flow processing. In the fly Drosophila melanogaster, a group of neurons called the horizontal system (HS) are involved in course control during high-speed translation. To understand how HS cells facilitate robust optic flow processing, we identified central networks that connect to HS cells using full brain electron microscopy datasets. These networks comprise three layers: convergent inputs from different, optic flow-sensitive cells, a middle layer with reciprocal, and lateral inhibitory interactions among different interneuron classes, and divergent output projecting to both the ventral nerve cord (equivalent to the vertebrate spinal cord), and to deeper regions of the fly brain. By combining two-photon optical imaging to monitor free calcium dynamics, manipulating GABA receptors and modeling, we found that lateral disinhibition between brain hemispheres enhance the selectivity to rotational visual flow at the output layer of the network. Moreover, asymmetric manipulations of interneurons and their descending outputs induce drifts during high-speed walking, confirming their contribution to steering control. Together, these findings highlight the importance of competitive disinhibition as a critical circuit mechanism for robust processing of optic flow, which likely influences course control and heading perception, both critical functions supporting navigation.

neuroscience↗

bioRxiv2018

optoPAD: a closed-loop optogenetics system to study the circuit basis of feeding behaviors

The regulation of feeding plays a key role in determining the fitness of animals through its impact on nutrition. Elucidating the circuit basis of feeding and related behaviors is an important goal in neuroscience. We recently used a system for closed-loop optogenetic manipulation of neurons contingent on the flys feeding behavior to dissect the impact of a specific subset of taste neurons on yeast feeding (Steck et al., 2018). Here we describe the development and validation of this system, which we term the optoPAD. We use the optoPAD to induce appetitive and aversive effects on feeding by activating or inhibiting gustatory neurons in closed loop - effectively creating virtual taste realities. The use of optogenetics allowed us to vary the dynamics and probability of stimulation in single flies and assess the impact on feeding behavior quantitatively and with high throughput. These data demonstrate that the optoPAD is a powerful tool to dissect the circuit basis of feeding behavior, allowing the efficient implementation of sophisticated behavioral paradigms to study the mechanistic basis of animals adaptation to dynamic environments.

neuroscience↗

bioRxiv2017

Internal amino acid state modulates yeast taste neurons to support protein homeostasis in Drosophila

To optimize fitness, animals must dynamically match food choices to their current needs. For drosophilids, yeast fulfils most dietary protein and micronutrient requirements. While several yeast metabolites activate known gustatory receptor neurons (GRNs) in Drosophila melanogaster, the chemosensory channels mediating yeast feeding remain unknown. Here we identify a class of proboscis GRNs required for yeast intake, and show that these GRNs act redundantly to mediate yeast feeding. While nutritional and reproductive states synergistically increase yeast appetite, we find a separation of these state signals at the level of GRN responses to yeast: amino acid but not mating state enhances yeast GRN gain. The sensitivity of sweet GRNs to sugar is not increased by protein deprivation, providing a potential basis for protein-specific appetite. The emerging picture is that different internal states act at distinct levels of a dedicated gustatory circuit to elicit nutrient-specific appetites towards a complex, ecologically relevant protein source.

neuroscience↗