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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

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

An emerging system to study photosymbiosis, brain regeneration, chronobiology, and behavior: the marine acoel symsagittifera roscoffensis

Arboleda, Enrique ; Hartenstein, Volker ; Martinez, Pedro ; Reichert, Heinrich ; Sen, Sonia ; Sprecher, Simon ; Bailly, Xavier

In: BioEssays, 2018, vol. 40, no. 10, p. 1800107

The acoel worm Symsagittifera roscoffensis, an early offshoot of the Bilateria and the only well-studied marine acoel that lives in a photosymbiotic relationship, exhibits a centralized nervous system, brain regeneration, and a wide repertoire of complex behaviors such as circatidal rhythmicity, photo/geotaxis, and social interactions. While this animal can be collected by the thousands and...

Université de Fribourg

Structure and development of the subesophageal zone of the Drosophila brain. II. Sensory compartments

Kendroud, Sarah ; Bohra, Ali A. ; Kuert, Philipp A. ; Nguyen, Bao ; Guillermin, Oriane ; Sprecher, Simon G. ; Reichert, Heinrich ; VijayRaghavan, Krishnaswamy ; Hartenstein, Volker

In: Journal of Comparative Neurology, 2018, vol. 526, no. 1, p. 33–58

The subesophageal zone (SEZ) of the Drosophila brain processes mechanosensory and gustatory sensory input from sensilla located on the head, mouth cavity and trunk. Motor output from the SEZ directly controls the movements involved in feeding behavior. In an accompanying paper (Hartenstein et al., 2017), we analyzed the systems of fiber tracts and secondary lineages to establish reliable...

Université de Fribourg

Functional brain regeneration in the acoel worm Symsagittifera roscoffensis

Sprecher, Simon G. ; Bernardo-Garcia, F. Javier ; Giesen, Lena van ; Hartenstein, Volker ; Reichert, Heinrich ; Neves, Ricardo ; Bailly, Xavier ; Martinez, Pedro ; Brauchle, Michael

In: Biology Open, 2015, vol. 4, no. 12, p. 1688–1695

The ability of some animals to regrow their head and brain after decapitation provides a striking example of the regenerative capacity within the animal kingdom. The acoel worm Symsagittifera roscoffensis can regrow its head, brain and sensory head organs within only a few weeks after decapitation. How rapidly and to what degree it also reacquires its functionality to control behavior however...

Université de Fribourg

A map of brain neuropils and fiber systems in the ant Cardiocondyla obscurior

Bressan, Joris M. A. ; Benz, Martin ; Oettler, Jan ; Heinze, Jürgen ; Hartenstein, Volker ; Sprecher, Simon G.

In: Frontiers in Neuroanatomy, 2015, vol. 8, p. 166

A wide spectrum of occupied ecological niches and spectacular morphological adaptations make social insects a prime object for comparative neuroanatomical studies. Eusocial insects have evolved complex societies based on caste polyphenism. A diverse behavioral repertoire of morphologically distinct castes of the same species requires a high degree of plasticity in the central nervous system. We...

Université de Fribourg

The Drosophila larval visual system: High-resolution analysis of a simple visual neuropil

Sprecher, Simon G. ; Cardona, Albert ; Hartenstein, Volker

In: Developmental Biology, 2011, p. -

The task of the visual system is to translate light into neuronal encoded information. This translation of photons into neuronal signals is achieved by photoreceptor neurons (PRs), specialized sensory neurons, located in the eye. Upon perception of light the PRs will send a signal to target neurons, which represent a first station of visual processing. Increasing complexity of visual processing...