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Université de Fribourg

Circadian and genetic modulation of visually-guided navigation in Drosophila larvae

Asirim, Ece Z. ; Humberg, Tim-Henning ; Maier, G. Larisa ; Sprecher, Simon G.

In: Scientific Reports, 2020, vol. 10, no. 1, p. 2752

Organisms possess an endogenous molecular clock which enables them to adapt to environmental rhythms and to synchronize their metabolism and behavior accordingly. Circadian rhythms govern daily oscillations in numerous physiological processes, and the underlying molecular components have been extensively described from fruit flies to mammals. Drosophila larvae have relatively simple nervous...

Université de Fribourg

Of circuits and brains: the origin and diversification of neural architectures

Martinez, Pedro ; Sprecher, Simon G.

In: Frontiers in Ecology and Evolution, 2020, vol. 8, p. 82

Nervous systems are complex cellular structures that allow animals to interact with their environment, which includes both the external and the internal milieu. The astonishing diversity of nervous system architectures present in all animal clades has prompted the idea that selective forces must have shaped them over evolutionary time. In most cases, neurons seem to coalesce into specific ...

Université de Fribourg

Single cell transcriptome atlas of the Drosophila larval brain

Brunet Avalos, Clarisse ; Maier, G. Larisa ; Bruggmann, Rémy ; Sprecher, Simon G.

In: eLife, 2019, vol. 8, p. e50354

Cell diversity of the brain and how it is affected by starvation, remains largely unknown. Here, we introduce a single cell transcriptome atlas of the entire Drosophila first instar larval brain. We first assigned cell-type identity based on known marker genes, distinguishing five major groups: neural progenitors, differentiated neurons, glia, undifferentiated neurons and non-neural cells....

Université de Fribourg

Mechanisms of vision in the fruit fly

Andres-Bragado, Lucia de ; Sprecher, Simon G.

In: Current Opinion in Insect Science, 2019, vol. 36, p. 25–32

Vision is essential to maximize the efficiency of daily tasks such as feeding, avoiding predators or finding mating partners. An advantageous model is Drosophila melanogaster, since it offers tools that allow genetic and neuronal manipulation with high spatial and temporal resolution, which can be combined with behavioral, anatomical and physiological assays. Recent advances have expanded our...

Université de Fribourg

Serial electron microscopic reconstruction of the drosophila larval eye: Photoreceptors with a rudimentary rhabdomere of microvillar-like processes

Hartenstein, Volker ; Yuan, Michaela ; Younossi-Hartenstein, Amelia ; Karandikar, Aanavi ; Bernardo-Garcia, F. Javier ; Sprecher, Simon G. ; Knust, Elisabeth

In: Developmental Biology, 2019, vol. 453, no. 1, p. 56–67

Photoreceptor cells (PRCs) across the animal kingdom are characterized by a stacking of apical membranes to accommodate the high abundance of photopigment. In arthropods and many other invertebrate phyla PRC membrane stacks adopt the shape of densely packed microvilli that form a structure called rhabdomere. PRCs and surrounding accessory cells, including pigment cells and lens-forming cells,...

Université de Fribourg

Multilevel regulation of the glass locus during Drosophila eye development

Fritsch, Cornelia ; Bernardo-Garcia, F. Javier ; Humberg, Tim-Henning ; Mishra, Abhishek Kumar ; Miellet, Sara ; Almeida, Silvia ; Frochaux, Michael V. ; Deplancke, Bart ; Huber, Armin ; Sprecher, Simon G.

In: PLOS Genetics, 2019, vol. 15, no. 7, p. e1008269

Development of eye tissue is initiated by a conserved set of transcription factors termed retinal determination network (RDN). In the fruit fly Drosophila melanogaster, the zinc-finger transcription factor Glass acts directly downstream of the RDN to control identity of photoreceptor as well as non-photoreceptor cells. Tight control of spatial and temporal gene expression is a critical...

Université de Fribourg

Muscarinic acetylcholine receptor signaling generates OFF selectivity in a simple visual circuit

Qin, Bo ; Humberg, Tim-Henning ; Kim, Anna ; Kim, Hyong S. ; Short, Jacob ; Diao, Fengqiu ; White, Benjamin H. ; Sprecher, Simon G. ; Yuan, Quan

In: Nature Communications, 2019, vol. 10, no. 1, p. 1–16

ON and OFF selectivity in visual processing is encoded by parallel pathways that respond to either light increments or decrements. Despite lacking the anatomical features to support split channels, Drosophila larvae effectively perform visually- guided behaviors. To understand principles guiding visual computation in this simple circuit, we focus on investigating the physiological properties...

Université de Fribourg

The digestive system of xenacoelomorphs

Gavilán, B. ; Sprecher, Simon G. ; Hartenstein, Volker ; Martinez, Pedro

In: Cell and Tissue Research, 2019, vol. 377, no. 3, p. 369–382

Interest in the study of Xenacoelomorpha has recently been revived due to realization of its key phylogenetic position as the putative sister group of the remaining Bilateria. Phylogenomic studies have attracted the attention of researchers interested in the evolution of animals and the origin of novelties. However, it is clear that a proper understanding of novelties can only be gained in...

Université de Fribourg

Initiated by CREB: resolving gene regulatory programs in learning and memory: switch in cofactors and transcription regulators between memory consolidation and maintenance network

Kaldun, Jenifer C. ; Sprecher, Simon G.

In: BioEssays, 2019, vol. 41, no. 8, p. 1900045

Consolidation of long‐term memory is a highly and precisely regulated multistep process. The transcription regulator cAMP response element‐binding protein (CREB) plays a key role in initiating memory consolidation. With time processing, first the cofactors are changed and, secondly, CREB gets dispensable. This ultimately changes the expressed gene program to genes required to maintain the...

Université de Fribourg

Glass confers rhabdomeric photoreceptor identity in Drosophila, but not across all metazoans

Bernardo‑Garcia, F. Javier ; Syed, Maryam ; Jékely, Gáspár ; Sprecher, Simon G.

In: EvoDevo, 2019, vol. 10, no. 1, p. 4

Across metazoans, visual systems employ different types of photoreceptor neurons (PRs) to detect light. These include rhabdomeric PRs, which exist in distantly related phyla and possess an evolutionarily conserved phototransduction cascade. While the development of rhabdomeric PRs has been thoroughly studied in the fruit fly Drosophila melanogaster, we still know very little about how they...