Biology subjects

Berger, S.

Publications and source records attributed to Berger, S..

3 recordsLinked to original sources

bioRxiv2018

The effects of drought and nutrient addition on soil organisms vary across taxonomic groups, but are constant across seasons

Anthropogenic global change alters the activity and functional composition of soil communities that are responsible for crucial ecosystem functions and services. Two of the most pervasive global change drivers are drought and nutrient enrichment. However, the responses of soil organisms to interacting global change drivers remain widely unknown. We tested the interactive effects of extreme drought and fertilization on soil biota ranging from microbes to invertebrates across seasons. We expected drought to reduce the activity of soil organisms and fertilization to induce positive bottom-up effects via increased plant productivity. Furthermore, we hypothesized fertilization to reinforce drought effects through enhanced plant growth, resulting in even dryer soil conditions. Our results revealed that drought had detrimental effects on soil invertebrate feeding activity and simplified nematode community structure, whereas soil microbial activity and biomass were unaffected. Microbial biomass increased in response to fertilization, whereas invertebrate feeding activity substantially declined. Notably, these effects were consistent across seasons. The dissimilar responses suggest that soil biota differ vastly in their vulnerability to global change drivers. As decomposition and nutrient cycling are driven by the interdependent concurrence of microbial and faunal activity, this may imply far-reaching consequences for crucial ecosystem processes in a changing world.

ecology↗

bioRxiv2017

Olfactory Receptors Are Required For Social Behavior And Neural Plasticity In Ants, As Evidenced By CRISPR-Mediated Gene Knockout

The chemosensory system is key to establishing and maintaining social structure in eusocial insects. Ants exhibit cooperative colonial behaviors reflective of an advanced form of sociality with an extensive dependency on communication. Cuticular hydrocarbons (CHCs) serve as pheromones and cues that regulate multiple aspects of social interactions and behaviors in ants. The perception of CHCs entails odorant receptor neurons (ORNs) that express specific odorant receptors (ORs) encoded by a dramatically expanded Or gene family in ants. Until recently, studies of the biological functions of ORs in eusocial insects were stymied by the lack of genetic tools. In most eusocial insect species, only one or a few queens in a colony can transmit the genetic information to their progeny. In contrast, any worker in the ant Harpegnathos saltator can be converted into a gamergate (pseudo-queen), and used as a foundress to engender an entire new colony and be crossed for genetic experiments. This feature facilitated CRISPR-Cas9 gene targeting to generate a germline mutation in the orco gene that encodes the obligate co-receptor whose mutation should significantly impact ant olfaction. Our results show that Orco exhibits a conserved role in the perception of general odorants but also a role in reproductive physiology and social behavior plasticity in ants. Surprisingly, and in contrast to other insect systems, the loss of OR functionality also dramatically reduces the development of the ant antennal lobe where ORNs project. Taken together, these findings open the possibility of studying the genetics of eusociality and provide inroads towards understanding the function of the expanded ORs family in eusocial insects in regulating caste determination, social communication and neuronal plasticity.

neuroscience↗

bioRxiv2017

High-Throughput Characterization of Protein-Protein Interactions by Reprogramming Yeast Mating

High-throughput methods for screening protein-protein interactions (PPIs) enable the rapid characterization of engineered binding proteins and interaction networks. While existing methods are powerful, none allow quantitative library-on-library characterization of PPIs in a modifiable extracellular environment. Here, we show that sexual agglutination of S. cerevisiae can be reprogrammed to link PPI strength with mating efficiency using yeast synthetic agglutination (YSA). Validation of YSA with 96 previously characterized interactions shows a strong log-linear relationship between mating efficiency and PPI strength for interactions with KDs ranging from 500 pM to 25 M. Using induced chromosomal translocation to pair barcodes representing interacting proteins, thousands of distinct interactions can be screened in a single pot. YSA binding interactions occur in a controllable extracellular environment, and thus studying the effects of environmental factors on PPI networks is possible. YSA enables the high-throughput, quantitative characterization of PPI networks in a fully defined extracellular environment at a library-on-library scale.

synthetic biology↗