Biology subjects

Jensen, A. M.

Publications and source records attributed to Jensen, A. M..

4 recordsLinked to original sources

bioRxiv2025

Dietary fibre promotes chronic whipworm infection through direct and time-dependent modulation of innate immunity

Dietary fibre regulates the microbiome and gut health but increases murine whipworm (Trichuris muris) infection through unclear mechanisms. We show that mice fed inulin-supplemented diets exhibit dysregulated innate antimicrobial defences and altered tryptophan metabolism during T. muris infection. Inhibiting tryptophan catabolism or neutralizing IL-27 and IL-18 in inulin-fed mice restored infection resistance. Notably, inulin led to chronic infection even in microbiota-depleted mice. Removing inulin within a critical immune development window rapidly restored anti-helminth immunity, indicating direct, time-dependent modulation of mucosal immune responses. Our findings reveal a previously unrecognized, direct influence of dietary fibre on mucosal immunity to parasitic infection, independent of the microbiome, highlighting the complex interplay between diet timing and host defence.

microbiology↗

bioRxiv2023

Overexpression of Rheb, a positive Tor regulator, reveals principles of rod outer segment size control

The outer segment of retinal rod photoreceptors is a highly modified cilium with the typical ciliary microtubular axoneme but additionally there are hundreds of densely packed, stacked, discrete intramembranous discs containing phototransduction machinery. The outer segment is continuously regenerated or renewed throughout the life of the animal through the combined processes of proximal growth and distal shedding. Since the pioneering experiments decades ago that demonstrated the process of rod outer segment renewal very little research has been directed towards understanding mechanistic principles of renewal and homeostasis, and many important questions remain unaddressed. The rod outer segment is a prime example of tight size control that is amenable to experimental and computational analyses. This study uses zebrafish molecular genetics with high resolution imaging, quantitative analyses, and computational modeling to uncover principles that regulate rod outer segment homeostatic length control. By genetically increasing rod outer segment growth, we show that outer segments lengthen and shedding does not accelerate to offset this added growth.

cell biology↗

bioRxiv2020

What happens to oak growth and survival when there is both competition and browsing?

Competition from neighboring vegetation and browsing by large herbivores are two of the most important factors affecting the structure and dynamics of temperate forests. While the previous literature has been able to identify individual negative effects from competition or browsing, no one has yet identified and quantified both the individual and the joint effects. Still, when plants face both competition and browsing, it is possible that the combined effect is not simply a sum of the individual negative effects, but perhaps a more complicated situation, where plants perform either better (in case there is also a facilitative effect from the neighboring vegetation) or worse (if the effects amplify each other) than they would if experiencing only one of the two factors. In this paper, we focus on regeneration of oak (Quercus robur L) to study these questions. We analyze a rich data set from a large long-term field experiment conducted at multiple sites in mixed temperate forests in southern Sweden over almost a decade. By the use of four separate treatments on each site - (i) neither competition, nor browsing, (ii) only competition, (iii) only browsing, and (iv) both competition and browsing - we can identify and quantify both the individual and combined effects of competition and browsing on oak growth and survival. We find that both competition and browsing individually affect growth and survival negatively. For growth, browsing has the largest effect, while competition is the larger problem from a survival point of view. When the plant experiences both competition and browsing, the combined, negative, effect is larger than either individual effect for survival, but for growth, the relationship is more complicated, and the surrounding woody vegetation offers at least some protection for the oak, reducing the negative effects from browsing.

ecology↗

bioRxiv2018

Kernel machine tests of association between brain networks and phenotypes

Applications of quantitative network analysis to functional brain connectivity have become popular in the last decade due to their ability to describe the general topological principles of brain networks. However, many issues arise when standard statistical analysis techniques are applied to functional magnetic resonance imaging (fMRI) connectivity maps. Frequently, summary measures of these maps, such as global efficiency and clustering coefficients, collapse the changing structures of graph topology from many scales to one. This can result in a loss of whole-brain spatio-temporal pattern information that may be significant in association and prediction analyses. Drawing from the electrical engineering field, the resistance perturbation distance is a quantification of similarity between graphs on the same vertex set that has been shown to identify changes in dynamic graphs, such as those from fMRI, while not being computationally expensive or result in a loss of information. This work proposes a novel kernel-based regression scheme that incorporates the resistance perturbation distance to better understand the association with biological phenotypes from fMRI using both simulated and real datasets.

neuroscience↗