Biology subjects

Rieger, J.

Publications and source records attributed to Rieger, J..

4 recordsLinked to original sources

bioRxiv2025

Domain-Specific Functional Network Adaptations Supporting Dual-Task Performance in Older Adults

Aging is associated with declines in both motor and cognitive functions, which are well captured by dual-task gait paradigms. However, the functional brain network mechanisms supporting motor and cognitive aspects of dual-task performance in aging remain unclear. We examined 40 older adults (50-80 years) and 20 younger adults (20-40 years) who performed a motor single-task (pedaling), a cognitive single-task (Go/NoGo), and a combined cognitive-motor dual-task during functional magnetic resonance Imaging (fMRI) using a custom-built MRI-compatible pedaling device. Behaviorally, older adults showed significant dual-task costs in motor performance, while cognitive performance was preserved. Neurally, older adults showed selective increases in connectivity within executive and motor-planning regions of cognitive networks, consistent with compensatory recruitment, whereas motor networks underwent broader reorganization, with strengthened frontoparietal control circuits but weakened cerebello-parietal and sensorimotor pathways. Multivariate analyses further revealed age-related differences in latent connectivity- behavior relationships: motor-network patterns in older adults were more dispersed, reflecting heterogeneous reorganization, whereas cognitive-network patterns were more overlapping across groups, suggesting relative preservation. These findings suggest that aging involves a domain-specific balance of resilience and vulnerability across brain networks and highlight motor-network adaption as a promising target for understanding why some older adults maintain function while others decline.

neuroscience↗

bioRxiv2025

Non-autonomous PMK-1/p38 MAPK signaling ensures homeostatic downregulation of germline stem cell proliferation in C. elegans

Stem cell underproliferation leads to tissue loss while over proliferation favors hyperplasia and tumorigenesis. Stem and progenitor proliferation rates are therefore usually coupled to the needs for their differentiated cellular progenies in the tissue(s) they serve. We used the C. elegans hermaphrodite reproductive system to understand how germline stem cell (GSC) proliferation is linked to sperm availability and oocyte usage. We developed a forward genetic screening method to identify genes required for the homeostatic downregulation of GSC proliferation when oocytes are not used, where germline homeostasis defective (ghd) mutants grow benign differentiated germline tumors. We provide evidence that the TIR-1/SARM1 metabolic sensor works together with the NIPI-3/TRIB1 pseudokinase to activate a canonical PMK-1/p38 MAPK signaling cascade in the somatic gonad, shut down the extracellular regulated kinase MPK-1/ERK, and couple GSC proliferation to oocyte needs. Similar multi-tissue signaling modules could underlie homeostatic stem cell regulation and prevent benign tumorigenesis in humans.

cell biology↗

bioRxiv2021

Single domain shark VNAR antibodies neutralize SARS-CoV-2 infection in vitro

Single domain shark VNAR antibodies can offer a viable alternative to conventional Ig-based monoclonal antibodies in treating COVID-19 disease during the current pandemic. Here we report the identification of neutralizing single domain VNAR antibodies selected against the SARS-CoV-2 spike protein derived from the Wuhan variant using phage display. We identified 56 unique binding clones that exhibited high affinity and specificity to the spike protein. Of those, 10 showed an ability to block both the spike protein receptor binding domain from the Wuhan variant and the N501Y mutant from interacting with recombinant ACE2 receptor in vitro. In addition, 3 antibody clones retained in vitro blocking activity when the E484K spike protein mutant was used. The inhibitory property of the VNAR antibodies was further confirmed for all 10 antibody clones using ACE2 expressing cells with spike protein from the Wuhan variant. The viral neutralizing potential of the VNAR clones was also confirmed for the 10 antibodies tested using live Wuhan variant virus in in vitro cell infectivity assays. Single domain VNAR antibodies due to their low complexity, small size, unique epitope recognition and formatting flexibility should be a useful adjunct to existing antibody approaches to treat COVID-19.

bioengineering↗

bioRxiv2018

Sentence processing is modulated by the current linguistic environment and a priori information: An fMRI study

Words are not processed in isolation but in rich contexts that are used to modulate and facilitate language comprehension. Here, we investigate distinct neural networks underlying two types of contexts. Firstly, the current linguistic environment, presented as the relative frequencies of two syntactic structures (prepositional object (PO) and double-object (DO)), which would either follow everyday linguistic experience or not. Secondly, preference towards one or the other structure depending on the verb; learned in everyday language use and stored in memory. German participants were reading PO and DO sentences in German while brain activity was measured with functional magnetic resonance imaging. Firstly, the anterior cingulate cortex (ACC) showed a pattern of activation that integrated the current linguistic environment with everyday linguistic experience. When the input did not match everyday experience, the unexpectedly frequent structure showed higher activation in the ACC than the other conditions and more connectivity from the ACC to posterior parts of the language network. Secondly, verb-based surprisal of seeing a structure given a verb (PO verb preference but DO structure presentation) resulted, within the language network (left inferior frontal and left middle/superior temporal gyrus) and the precuneus, in increased activation compared to a predictable situation. In conclusion, 1) beyond the canonical language network, brain areas engaged in cognitive control, such as the ACC, might use the statistics of syntactic structures to facilitate language comprehension, 2) the language network is directly engaged in processing verb preferences. These two networks show distinct influences on sentence processing.

neuroscience↗