Biology subjects

Sayin, S.

Publications and source records attributed to Sayin, S..

7 recordsLinked to original sources

bioRxiv2025

Habitat structure and social behavior - the development of social phenotypes in the desert locust

Habitat structure has fundamental implications for behavior, foraging dynamics, and the social organization of animals. Locusts, which exhibit both a sedentary solitarious morph and a gregarious swarm-forming one, provide a powerful model to investigate how environmental factors shape social phenotypes. We conducted long-term continuous monitoring of locusts raised in semi-natural arenas with either clumped or distributed resources. Our findings reveal that clumped overnight roosting led to an increased propensity for coordinated marching the following day, a key precursor of swarm formation. These patterns became clearer during larval development, driving divergence in social affinity and group dynamics between habitat groups. At the molecular level, transcriptomic analysis identified a narrow set of differentially expressed genes, with enrichment in neuromodulatory and metabolic pathways, including candidates linked to monoaminergic signaling and juvenile hormone biology, such as a takeout-like JH-binding gene. These results demonstrate that spatial resource configuration is sufficient for lasting differences in individual and group dynamics and offer insight into the molecular processes mediating spontaneous, habitat-driven, phenotypic changes in a devastating plague insect.

animal behavior and cognition↗

bioRxiv2025

Bacterial population dynamics during colonization of solid tumors

Bacterial colonization of tumors is widespread, yet the dynamics during colonization remain underexplored. Here we discover strong variability in the sizes of intratumor bacterial clones and use this variability to infer the mechanisms of colonization. We monitored bacterial population dynamics in murine tumors after introducing millions of genetically barcoded Escherichia coli cells. Results from intravenous injection revealed that roughly a hundred bacteria seeded a tumor and that colonizers underwent rapid, yet highly nonuniform growth. Within a day, bacteria reached a steady-state and then sustained load and clone diversity. Intratumor injections, circumventing infection bottlenecks, revealed that the nonuniformity persists and that the sizes of bacterial progenies followed a scale-free distribution. Theory suggested that our observations are compatible with a growth model constrained by a local niche load, global resource competition, and noise. Our work provides the first dynamical model of tumor colonization and may allow distinguishing genuine tumor microbiomes from contamination.

systems biology↗

bioRxiv2025

The Innexin 7 gap junction protein contributes to synchronized activity in the Drosophila antennal lobe and regulates olfactory function

In the mammalian olfactory bulb (OB), gap junctions coordinate synchronous activity among mitral and tufted cells to process olfactory information. In insects, gap junctions are also present in the Antennal Lobe (AL), a structure homologous to the mammalian OB. The invertebrate gap junction protein ShakB contributes to electrical synapses between AL Projections Neurons (PNs) in Drosophila. Other gap junction proteins, including Innexin 7 (Inx7), are also expressed in the Drosophila AL, but little is known about their contribution to intercellular communication during olfactory information processing. Here we report spontaneous calcium transients in PNs grown in cell culture that are highly synchronous when these neurons are physically connected. RNAi-mediated knock down of Inx7 in cultured PNs blocks calcium transient neuronal synchronization. In vivo, downregulation of Inx7 in the AL impairs both vinegar-induced electrophysiological calcium responses and behavioral responses to this appetitive stimulus. These results demonstrate that Inx7-encoded gap junctions functionally coordinate PN activity and modulate olfactory information processing in the adult Drosophila AL.

neuroscience↗

bioRxiv2023

Synergistic olfactory processing for social plasticity in desert locusts

1Desert locust plagues threaten the food security of millions. Central to their formation is crowding-induced social plasticity from solitarious to gregarious phenotypes. We investigated the impact of population density changes on locusts foraging choices and their neurobiology by examining how relevant food and social odors are coded in the antennal lobe. Our analysis shows that gregarious locusts are highly attentive to social cues during foraging, with olfaction playing an essential role. Using calcium imaging, we show that corresponding odors are encoded by projection neurons, revealing a stable combinatorial response map. Transient dynamics in the glomeruli converge into temporally evolving response motifs in the somata that differ between gregarious and solitarious insects. The dynamics of response motifs facilitate a crowding-dependent synergy between olfactory processing of food-related and social odors. Our study demonstrates the effectiveness of calcium imaging for locust olfaction, suggesting a crowding-induced adaptation to enhance food detection in swarms. 2 TeaserIn dense swarms, desert locusts optimize foraging efficiency by exhibiting an enhanced olfactory response to food odors.

neuroscience↗

bioRxiv2022

Evolved bacterial resistance to the chemotherapy gemcitabine modulates its efficacy

Drug metabolism by the microbiome can influence anti-cancer treatment success. We previously suggested that chemotherapies with antimicrobial activity can select for adaptations in bacterial drug metabolism that can inadvertently influence the hosts chemoresistance. We demonstrated that evolved resistance against fluoropyrimidine chemotherapy lowered its efficacy in worms feeding on drug-evolved bacteria (Rosener et al., 2020). Here we examine a model system that captures local interactions that can occur in the tumor microenvironment. Gammaproteobacteria colonizing pancreatic tumors can degrade the nucleoside-analog chemotherapy gemcitabine and, in doing so, can increase the tumors chemoresistance. Using a genetic screen in Escherichia coli, we mapped all loss-of-function mutations conferring gemcitabine resistance. Surprisingly, we found that one third of resistance mutations increase or decrease bacterial drug breakdown and therefore can either lower or raise the gemcitabine load in the local environment. Experiments in three E. coli strains revealed that evolved adaptation converged to inactivation of the nucleoside permease NupC, an adaptation that increased the drug burden on co-cultured cancer cells. The two studies provide complementary insights on the potential impact of microbiome adaptation to chemotherapy by showing that bacteria-drug interactions transpire locally and systemically and can influence chemoresistance in the host.

systems biology↗

bioRxiv2019

Salt Inducible Kinases as Novel Notch Interactors in the Developing Drosophila Retina

Developmental processes require strict regulation of proliferation, differentiation and patterning for the generation of final organ size. Aberrations in these fundamental events are critically important in understanding tumorigenesis and cancer progression. Salt inducible kinases (Siks) are evolutionarily conserved genes involved in diverse biological processes, including salt sensing, metabolism, muscle and skeletal development. Recent findings implicate SIKs in tumor suppression or progression. However, their role in development remains largely unknown.\n\nUsing a sensitized tumor model in the Drosophila eye, we show that perturbations of Sik function exacerbates tumor-like tissue overgrowth and metastasis. Furthermore, we show that both Drosophila Sik genes, Sik2 and Sik3, are required for proper eye development. We propose that an important target of Siks may be the Notch pathway, as we demonstrate epistasis between Siks and Notch pathway members and identify putative phosphorylation motifs on Notch, Delta and Fringe. Finally, we investigate Sik expression in the developing retina and show that Sik2 is expressed in all photoreceptors in close proximity to cell junctions, while Sik3 appears to be expressed specifically in R3/R4 cells in the developing eye. Combined, our data suggest that Sik genes are important in tissue specification, growth, and that their dysregulation may contribute to tumor formation.

developmental biology↗

bioRxiv2018

Specific octopaminergic neurons arbitrate between perseverance and reward in hungry Drosophila

In pursuit of palatable food, hungry animals mobilize significant energy resources and overcome obstacles, exhaustion and fear. Their perseverance depends on metabolic state, internal motivation and the expected benefit. Sustained commitment to a trying task is crucial, however, disengagement from one behavior to engage into another can be essential for optimal adaptation and survival. How neural circuits allow prioritizing perseverance over withdrawal based on the animals need is not understood. Using a single fly spherical treadmill, we show that hungry flies display increasing perseverance to track a food odor in the repeated absence of the predicted food reward. While this perseverance is mediated by a group of dopaminergic neurons, a subset of neurons expressing octopamine, the invertebrate counterpart of noradrenaline, provide reward feedback and counteract dopamine-motivated food seeking. Our data and modeling suggest that two important neuromodulators tally internal and external signals to coordinate motivation-dependent antagonistic behavioral drives: perseverance vs. change of behavior.\n\n\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=87 SRC=\"FIGDIR/small/259119_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (21K):\norg.highwire.dtl.DTLVardef@9833e1org.highwire.dtl.DTLVardef@7616d4org.highwire.dtl.DTLVardef@d4e8bforg.highwire.dtl.DTLVardef@1fc615c_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LILack of reward stimulates perseverance, and not quitting.\nC_LIO_LIDopaminergic neurons previously implicated in aversive learning promote perseverance.\nC_LIO_LISugar responsive octopaminergic neurons directly counteract perseverant odor tracking through a downstream inhibitory neuron.\nC_LIO_LIComputational modeling supports a simple neural circuit featuring antagonistic functions for dopamine and octopamine as tallies of expense and gain.\nC_LI

neuroscience↗