Biology subjects

Buser, C.

Publications and source records attributed to Buser, C..

2 recordsLinked to original sources

bioRxiv2025

Loss of Vertically-Inherited Totiviruses and Toxin-Encoding Satellites in Killer Yeast Evidences Intracellular Conflict in Natural Populations

Saccharomyces cerevisiae is occasionally infected by totiviruses and their toxin-encoding satellites. Totiviruses and their satellites coexist but with an asymmetric dependence on the totivirus for maintenance inside the host cell. Satellites provide their yeast hosts with inhibitory toxins and the necessary self-immunity; loss of the satellite equates to loss of immunity. Because mycoviruses lack known extracellular stages, and sex is considered rare, mycoviruses are assumed to be transmitted vertically, implying infection states should correlate with host genotypes. However, totivirus-satellite coinfections are rarely examined in natural populations, leaving their associations with host genotypes poorly understood. We screened a multiyear population of S. cerevisiae isolates from New Zealand to examine the stability of host-virus associations over time, both within and across genotypes. While 55% of wild isolates harbored infections, only 37% of these included toxin-encoding satellites. Genotypes that persisted across years typically maintained consistent infection states. However, we observed stepwise transitions including acquisitions of totiviruses and satellites. Genotypes clustered strongly by infection state, supporting vertical transmission while suggesting that outcrossing is not responsible for the mycovirus acquisitions. Despite infection changes, genotype clustering by infection state remained intact, suggesting transitions are transient and that host genotypes may have optimal totivirus-satellite infection states.

evolutionary biology↗

bioRxiv2022

Botulinum neurotoxin accurately separates tonic vs phasic transmission and reveals heterosynaptic plasticity rules in Drosophila

In developing and mature nervous systems, diverse neuronal subtypes innervate common targets to establish and maintain functional neural circuits. A major challenge towards understanding the structural and functional architecture of neural circuits is to separate these inputs and determine their intrinsic and heterosynaptic relationships. The Drosophila larval neuromuscular junction is a powerful model system to study these questions, where two glutamatergic motor neurons, the strong phasic-like Is and weak tonic-like Ib, co-innervate individual muscle targets to coordinate locomotor behavior. However, complete neurotransmission from each input has never been electrophysiologically separated. We have developed a botulinum neurotoxin, BoNT-C, that eliminates both spontaneous and evoked neurotransmission without perturbing synaptic growth or structure, enabling the first approach that accurately isolates input-specific neurotransmission. Selective expression of BoNT-C in Is or Ib motor inputs disambiguates functional properties of each input. Importantly, the composite values of Is and Ib neurotransmission can be fully recapitulated by isolated physiology from each input. Finally, selective silencing by BoNT-C does not induce heterosynaptic structural or functional plasticity at the convergent input. Thus, BoNT-C establishes the first approach to cleanly separate neurotransmission between tonic vs phasic neurons and defines heterosynaptic plasticity rules in a powerful model glutamatergic circuit.

neuroscience↗