Biology subjects

Carlsson, H.

Publications and source records attributed to Carlsson, H..

15 recordsLinked to original sources

bioRxiv2026

Dietary fibre responses emerge through host-dietary regime interplay: Apple pectin modulates immune reactivity in adult zebrafish

Dietary fibres are rarely consumed independently. Instead, they form part of an overall diet that includes dietary fibres from different sources, in varying amounts and consumed under different feeding patterns. Here, we tested how dietary regimes containing apple pectin, oat {beta}-glucan, or cellulose shaped the host. We analysed gut microbiome composition by 16S rRNA sequencing, measured brain and intestinal SCFA profiles by targeted metabolomics, and assessed immunomodulation by measuring gene expression systemically in the blood and locally in the spleen, as well as intestinal enzyme activity. The dietary intervention was conducted for 12 weeks on adult female and male zebrafish (Danio rerio). Our results show that the gut microbial composition can be relatively stable across different dietary fibre exposure patterns yet still vary significantly between the sexes. Additionally, the effect of sex on the gut microbiome may become more evident when dietary fibres are administered at high dosages, but intermittently. Dietary fibre regimes can alter intestinal short-chain fatty acid profiles more readily than brain profiles, which show a stronger sexually dimorphic response. Interestingly, apple pectin modulated the zebrafish immune response through interactions dependent on the overall regime, tissue, sex, and host immune status. Notably, tissue il1b gene expression differed depending on how apple pectin was administered and the host's physiological state. Collectively, our study emphasises the highly context-specific effects of dietary fibres, shaped by the dynamic interplay between the overall dietary regime and intertwined host factors.

systems biology↗

bioRxiv2025

Lifespan-extending downregulation of insulin signalling reduces germline mutation load

Reduced insulin/IGF-1 signalling (IIS) robustly extends lifespan and enhances somatic stress resistance across taxa, yet its consequences for germline genome integrity remain unclear. Here we combine multigenerational mutation accumulation with whole-genome sequencing in C. elegans to test whether adulthood-only IIS downregulation can simultaneously promote somatic maintenance and limit germline mutational burden. We reduced IIS by adult-onset daf-2 RNAi in wild-type and heritable RNAi-deficient (hrde-1) backgrounds, allowing either spontaneous or UV-induced germline mutations to accumulate over multiple generations. In wild-type animals, reduced IIS lowered germline single-nucleotide mutation rates by up to [~]50% and prevented the UV-induced elevation in mutation rate, without detectable costs to fecundity or lineage persistence. By contrast, in hrde-1 mutants the same intervention increased both point mutations and transposable-element-driven insertions under UV exposure, accelerating lineage extinction. Thus, the genome-protective effect of reduced IIS critically requires the germline nuclear Argonaute HRDE-1, which mediates small-RNA-guided epigenetic silencing. Functional annotation of germline variants revealed enrichment in pathways linked to development, cellular maintenance and conserved longevity regulators, including IIS and mTOR, and identified high-impact mutations in genes with human orthologs implicated in neurodegeneration and cancer. Our findings show that IIS can coordinate somatic and germline maintenance in concert, rather than in competition, through an HRDE-1-dependent epigenetic pathway. This work positions nutrient-sensing IIS as a central regulator of germline genome stability and suggests that IIS downregulation can reduce germline mutation load while extending lifespan, with broad implications for biogerontology and evolutionary biology.

evolutionary biology↗

bioRxiv2024

Microbially produced bile acids are associated with high levels of IgG autoantibodies and worse mental wellbeingin fibromyalgia subjects

Fibromyalgia (FM) is a disease primarily associated with chronic widespread pain, but other common symptoms are anxiety and depression. We previously proposed that autoimmunity contributes to FM based on findings of increased immunoglobulin G binding to satellite glial cells (anti-SGC IgG) in FM subjects compared to healthy controls (HC). Emerging research suggests that an altered gut microbiota composition is connected to psychological symptoms in FM rather than pain. Gut microbiota can produce or alter bile acids (BAs) and short-chain fatty acids (SCFAs), which have immune and inflammatory functions. Here, we investigate alterations in BA and SCFA concentrations in FM subjects compared to healthy controls (HC) and potential associations with FM symptoms and anti-SGC IgG levels. Bile acids and SCFAs were quantified using liquid chromatography coupled with high-resolution mass spectrometry and anti-SGC IgG levels were assessed with immunocytochemistry. The correlations between FM symptoms, anti-SGC IgG levels, and serum concentrations of 24 BAs and 11 SCFAs in 35 FM subjects and 32 matched HC were examined. Fibromyalgia subjects had significantly higher levels of microbially produced BAs than HC. Strikingly, 11 out of 24 BAs were significantly elevated in FM subjects with high, compared to those with low, anti-SGC IgG levels. Concentrations of specific BAs were associated with increased disease severity and worse mental well-being. These results revealed increased levels of secondary BAs in FM subjects compared to HC. The strong association between BAs, anti-SGC IgG levels, and mental well-being may help elucidate the importance of BAs in the psychological symptoms of FM. Significance statementFibromyalgia (FM) is a chronic pain syndrome that significantly impacts an individuals quality of life. In addition to persistent pain, people with FM often experience depression, anxiety, and irritable bowel syndrome. Previously, we identified autoantibodies that bind to satellite glial cells in the dorsal root ganglia associated with more severe FM symptoms. Our current results demonstrate a novel association between these autoantibodies in FM and bile acids (BAs). Bile acids are essential for lipid metabolism but also act as signaling molecules. We show that patients with elevated levels of autoantibodies also exhibit increased levels of BAs. Furthermore, the BAs strongly correlate with worse FM symptom severity, particularly affecting mental well-being. Our study suggests that lowering BA levels could alleviate the psychological symptoms associated with FM.

neuroscience↗

bioRxiv2024

Fibromyalgia patients have altered lipid concentrations associated with disease symptom severity and anti-satellite glial cell IgG antibodies

Autoimmunity and immunoglobulin G (IgG) autoantibodies may contribute to pain in a subset of fibromyalgia (FM) patients. Previously, we saw that IgG from FM patients induces pain-like behavior in mice and binds to satellite glial cells (anti-SGC IgG). The anti-SGC IgG levels were also associated with more severe symptomatology. Lipid metabolism in FM subjects is altered with lysophosphatidylcholines (LPCs) acting as pain mediators. The relationship between autoantibodies, lipid metabolism, and FM symptomatology remains unclear. We analyzed serum lipidomics with liquid chromatography mass spectrometry, anti-SGC IgG levels, and clinical measures in 35 female FM subjects and 33 age- and body mass index-balanced healthy controls (HC). Fibromyalgia subjects with higher anti-SGC IgG levels experienced more intense pain than those with lower levels. Sixty-three lipids were significantly altered between FM subjects and HC or between FM subjects with severe (FM severe) and mild symptoms (FM mild). Compared to HC, FM subjects had lower concentrations of lipid species belonging to the classes LPC (n = 10), lysophosphatidylethanolamine (n = 7), phosphatidylcholine (n = 4), and triglyceride (n = 5), but higher concentrations of diglyceride (n = 3). Additionally, FM severe had higher LPC 19:0, 22:0, and 24:1 and lower sphingomyelin (n = 9) concentrations compared to FM mild. A positive association was seen for LPC 22:0 and 24:1 with pain intensity and anti-SGC IgG levels in FM subjects. Taken together, our results suggest an association between altered lipid metabolism and autoimmune mechanisms in FM. PerspectiveOur results suggest an association between the postulated autoimmunity in FM and lipids that can act as pain mediators.

neuroscience↗

bioRxiv2023

Early-adulthood intermittent fasting and reduced insulin/IGF-1 signalling additively increase lifespan and slow down reproductive ageing

The developmental theory of ageing proposes that age-specific decline in the force of natural selection results in suboptimal levels of gene expression in adulthood, leading to functional senescence. This theory explicitly predicts that optimising gene expression in adulthood can ameliorate functional senescence and improve fitness. Reduced insulin/IGF-1 signalling (rIIS) extends the reproductive lifespan of Caenorhabditis elegans at the cost of reduced reproduction. Here, we show that adulthood-only rIIS improves late-life reproduction without any detrimental effects on other life-history traits in both benign and stressful conditions. Remarkably, we show that rIIS additively extends late-life reproduction and lifespan when animals are exposed to a fluctuating food environment - intermittent fasting (IF) - resulting in reduced food intake in early adulthood. Full factorial genome-wide RNA-Seq across the life course demonstrated that IF and rIIS modulate the age-specific expression of pro-longevity genes. IF, rIIS and combined IF + rIIS treatment downregulated genes involved in peptide metabolism in early life and differentially regulated immunity genes in later life. Importantly, combined IF + rIIS treatment uniquely regulated a large cluster of genes in mid-life that are associated with immune response. These results suggest that optimising gene expression in adulthood can decelerate reproductive ageing and increase fitness.

molecular biology↗

bioRxiv2023

Sex-specific growth and lifespan effects of germline removal in the dioecious nematode Caenorhabditis remanei

Germline regulates the expression of life-history traits and mediates the trade-off between reproduction and somatic maintenance. However, germline maintenance in itself can be costly, and the costs can vary between the sexes depending on the number of gametes produced across the lifetime. We tested this directly by germline ablation using glp-1 RNAi in a dioecious nematode Caenorhabditis remanei. Germline removal strongly increased heat-shock resistance in both sexes, thus confirming the role of the germline in regulating somatic maintenance. However, germline removal resulted in increased lifespan only in males. High costs of mating strongly reduced lifespan in both sexes and obliterated the survival benefit of germline-less males even though neither sex produced any offspring. Furthermore, germline removal reduced male growth before maturation but not in adulthood, while female growth rate was reduced both before and especially after maturation. Thus, germline removal improves male lifespan without major growth costs, while germline-less females grow slower and do not live longer than reproductively functional counterparts in the absence of environmental stress. Overall, these results suggest that germline maintenance is costlier for males than for females.

evolutionary biology↗

bioRxiv2021

Beneficial cumulative effects of old parental age on offspring fitness

Old parental age is commonly associated with negative effects on offspring life-history traits. Such parental effect senescence is predicted to have a cumulative detrimental effect over successive generations. However, old parents may benefit from producing high-quality offspring when these compete for seasonal resources. Thus, old parents may choose to increase investment in their offspring, thereby producing fewer but larger and more competitive progeny. We show that Caenorhabditis elegans hermaphrodites increase parental investment with advancing age, resulting in fitter offspring who reach their reproductive peak earlier. Remarkably, these effects increased over six successive generations of breeding from old parents and were subsequently reversed following a single generation of breeding from a young parent. These results contradict the theory that old parents transfer a cumulative detrimental "ageing factor" to their offspring. Instead, our findings support the hypothesis that offspring of old parents receive more resources and convert them into increasingly faster life-histories.

evolutionary biology↗

bioRxiv2020

Reduced insulin signalling in adulthood protects soma and germline under mutation accumulation

Adulthood-only downregulation of insulin/IGF-1 signalling (IIS), an evolutionarily conserved pathway regulating resource allocation between somatic maintenance and reproduction, increases lifespan without fecundity cost in the nematode, Caenorhabditis elegans. However, long-term multigenerational effects of reduced IIS remain unexplored and are proposed to carry costs for offspring quality. To test this hypothesis, we ran a mutation accumulation (MA) experiment and downregulated IIS in half of the 400 MA lines by silencing daf-2 gene expression using RNA interference (RNAi) across 40 generations. Contrary to the prediction, adulthood-only daf-2 RNAi reduced extinction of MA lines both under UV-induced and spontaneous mutation accumulation. Fitness of the surviving UV-induced MA lines was higher under daf-2 RNAi. Reduced IIS increased intergenerational F1 offspring fitness under UV stress but had no quantifiable transgenerational effects. Functional hrde-1 was required for the benefits of multigenerational daf-2 RNAi. Overall, we found net benefit to fitness from multigenerational reduction of IIS and the benefits became more apparent under stress. Because reduced daf-2 expression during development carries fitness costs, we suggest that our findings are best explained by the developmental theory of ageing, which maintains that the decline in the force of selection with age results in poorly regulated gene expression in adulthood.

evolutionary biology↗

bioRxiv2020

Transgenerational fitness effects of lifespan extension by dietary restriction in Caenorhabditis elegans

Dietary restriction increases lifespan in a broad variety of organisms and improves health in humans. However, long-term transgenerational consequences of dietary interventions are poorly understood. Here we investigated the effect of dietary restriction by temporary fasting (TF) on mortality risk, age-specific reproduction and fitness across three generations of descendants in C. elegans. We show that while TF robustly reduces mortality risk and improves late-life reproduction in the parental generation (P0), it has a wide range of both positive and deleterious effects on future generations (F1-F3). Remarkably, great-grandparental exposure to TF in early-life reduces fitness and increases mortality risk of F3 descendants to such an extent that TF no longer promotes a lifespan extension. These findings reveal that transgenerational trade-offs accompany the instant benefits of dietary restriction underscoring the need to consider fitness of future generations in pursuit of healthy ageing.

evolutionary biology↗

bioRxiv2020

Variable environments select for short lifespan

The role of environmental variation in the evolution of lifespan is contested. Classic theory predicts that variable environments favour the evolution of long life, but recent theoretical work suggests that environmental variation can instead select for shorter lifespan when the changes are rapid relative to generation time. Here, we used experimental evolution to study how lifespan evolves in response to temperature variation. Genetically diverse populations of the outcrossing nematode Caenorhabditis remanei, were exposed to a novel, stressful temperature for 30 generations, under stable, gradually warming or fluctuating thermal regimes. We found the evolution of shorter lifespan in populations exposed to environments that fluctuated within the individuals lifetime, compared to populations evolving in stable warm temperature. While climate warming is predicted to increase environmental stochasticity, our results show that fast temperature cycles can rapidly select for short lifespan.

evolutionary biology↗

bioRxiv2020

Evolutionary causes of lifespan extension by dietary restriction: linking theory and mechanisms

Dietary restriction (DR), reduced food intake without malnutrition, increases lifespan across a broad range of taxa, but the evolutionary underpinning of this phenomenon is poorly understood. The resource reallocation hypothesis proposes that dietary restricted animals divert resources from reproduction to somatic maintenance to increase survival in times of nutrient scarcity in favour of future reproduction. The "longevity by-product" hypothesis proposes instead that dietary restricted animals increase nutrient recycling via autophagy to maximise immediate reproduction, thereby reducing cellular toxic waste and leading to longer lifespan as an unselected by-product. The "longevity by-product" hypothesis makes a unique prediction that blocking autophagy in DR animals will simultaneously reduce lifespan and reproduction. To test the adaptive value of autophagy under dietary restriction, we inhibited autophagy using bec-1 RNAi knockdown in DR and fully-fed Caenorhabditis elegans nematodes. Our findings confirm that autophagic inhibition results in a significantly shorter lifespan under DR, suggesting that autophagy is important for survival in times of famine. Remarkably, we also show that inhibiting autophagy throughout adult life significantly increases reproduction in both dietary restricted and fully fed worms. Moreover, this did not come at a transgenerational cost to offspring fitness. Our results suggest that autophagy is an energetically costly process that reduces resources available for reproduction, but is necessary for survival during famine, and are thus consistent with the resource reallocation hypothesis.

evolutionary biology↗

bioRxiv2019

Cost-free lifespan extension via optimisation of gene expression in adulthood supports the developmental theory of ageing

Classic theory upholds that energy trade-offs between reproduction and somatic maintenance underpin the evolution of ageing and lifespan. In contrast, the developmental theory of ageing (DTA) suggests that organismal senescence is caused by dysregulated gene expression in adulthood due to decline in selection gradients with age. The DTA predicts that age-specific optimisation of gene expression can improve survival without fitness costs. Here we investigated consequences for survival, reproduction, egg size and fitness of early-life, adulthood and post-reproductive onset of RNAi knockdown of five well-described \"longevity\" genes involved in key biological processes in Caenorhabditis elegans nematodes: nutrient-sensing signalling via insulin/IGF-1 (age-1) and target-of-rapamycin (raga-1) pathways, global protein synthesis (ifg-1), global protein synthesis in somatic cells (ife-2) and mitochondrial respiration (nuo-6). Downregulation of these genes in adulthood and/or during post-reproductive period improves survival, while there was little evidence for a link between impaired reproduction and extended lifespan. Our findings demonstrate that hyper-function of diverse physiological processes after sexual maturation is detrimental for survival. Therefore, optimisation of gene expression in adult organisms can ameliorate ageing and increase fitness.

evolutionary biology↗

bioRxiv2019

Environmental variation mediates the evolution of anticipatory parental effects

Theory maintains that when future environment is predictable, parents should adjust the phenotype of their offspring to match the anticipated environment. The plausibility of positive anticipatory parental effects is hotly debated and the experimental evidence for the evolution of such effects is currently lacking. We experimentally investigated the evolution of anticipatory maternal effects in a range of environments that differ drastically in how predictable they are. Populations of the nematode Caenorhabditis remanei, adapted to 20{degrees}C, were exposed to a novel temperature (25{degrees}C) for 30 generations with either positive or zero correlation between parent and offspring environment. We found that populations evolving in novel environments that were predictable across generations evolved a positive anticipatory maternal effect, since they required maternal exposure to 25{degrees}C to achieve maximum reproduction in that temperature. In contrast, populations evolving under zero environmental correlation had lost this anticipatory maternal effect. Similar but weaker patterns were found if instead rate-sensitive population growth was used as a fitness measure. These findings demonstrate that anticipatory parental effects evolve in response to environmental change so that ill-fitting parental effects can be rapidly lost. Evolution of positive anticipatory parental effects can aid population viability in rapidly changing but predictable environments. Impact summaryParents can help their offspring by adjusting offsprings phenotype to match their environment. Such anticipatory parental effects would be beneficial, but only if parents can accurately predict the environment in which their offspring will develop and live. The plausibility of such anticipatory parental effects is hotly debated. The theory is clear that the predictability of the environment should play a defining role. We used an "experimental evolution" approach in a fast reproducing nematode worm Caenorhabditis remanei to tackle this question and follow the evolution of parental effects in different environments in real-time. We found that populations evolving in a novel but predictable environment indeed had anticipatory parental effects that increased fitness of their offspring in that environment. In contrast, when evolving in an unpredictable environment where such parental effects would be disadvantageous, the parental effect was rapidly lost in evolution. Our novel experimental environments were constructed by exposing worms to increased temperature. Anticipatory parental effects play an important role in adaptation to novel environments and will affect the viability of populations under climate heating.

evolutionary biology↗

bioRxiv2018

Reduced insulin/IGF-1 signalling in adult parents increases offspring fitness

Classical theory maintains that ageing evolves via energy trade-offs between reproduction and survival leading to accumulation of unrepaired cellular damage with age. In contrast, the emerging new theory postulates that ageing evolves because of deleterious late-life hyper-function of reproduction-promoting genes leading to excessive biosynthesis in late-life. The hyper-function theory uniquely predicts that optimizing nutrient-sensing molecular signalling in adulthood can simultaneously postpone ageing and increase Darwinian fitness. Here we show that reducing evolutionarily conserved insulin/IGF-1 nutrient-sensing signalling via daf-2 RNA interference (RNAi) fulfils this prediction in Caenorhabditis elegans nematodes. Long-lived daf-2 RNAi parents showed normal fecundity as self-fertilizing hermaphrodites and improved late-life reproduction when mated to males. Remarkably, the offspring of daf-2 RNAi parents had higher Darwinian fitness across three different genotypes. Thus, reduced nutrient-sensing signalling in adulthood improves both parental longevity and offspring fitness supporting the emerging view that sub-optimal gene expression in late-life lies at the heart of ageing. Impact StatementUnderstanding mechanisms underpinning ageing is fundamental to improving quality of life in an increasingly long-lived society. Recent breakthroughs have challenged the long-standing paradigm that the energy trade-off between reproduction and somatic maintenance causes organismal senescence via slow accumulation of unrepaired cellular damage with age. The emerging new theory of ageing provides a conceptually novel framework by proposing that ageing is a direct consequence of physiological processes optimized for early-life function, such as growth and early-life reproduction, that are running too high (i.e. at hyperfunction) in late adulthood. Contrary to the classic view based on damage accumulation, the hyperfunction theory proposes that suboptimal gene expression in late-life causes ageing via excessive biosynthesis. Thus, the hyperfunction theory uniquely predicts that longevity and Darwinian fitness can be simultaneously increased by reducing unnecessarily high levels of nutrient-sensing signalling in adulthood. Here we show that reducing evolutionarily conserved nutrient-sensing signalling pathway fulfils this prediction in Caenorhabditis elegans nematodes. We found that downregulation of the insulin/IGF-1 signalling in adult C. elegans nematodes not only improves longevity but, most intriguingly, increases fitness of the resulting offspring in the next generation. We found support for increase in offspring fitness across different genetic backgrounds. Our findings contradict the theoretical conjecture that energy trade-offs between growth, reproduction and longevity is the universal cause of senescence and provide strong experimental support for the emerging hyperfunction theory of ageing.

genetics↗

bioRxiv2018

Data-adaptive pipeline for filtering and normalizing metabolomics data.

IntroductionUntargeted metabolomics datasets contain large proportions of uninformative features and are affected by a variety of nuisance technical effects that can bias subsequent statistical analyses. Thus, there is a need for versatile and data-adaptive methods for filtering and normalizing data prior to investigating the underlying biological phenomena.\n\nObjectivesHere, we propose and evaluate a data-adaptive pipeline for metabolomics data that are generated by liquid chromatography-mass spectrometry platforms.\n\nMethodsOur data-adaptive pipeline includes novel methods for filtering features based on blank samples, proportions of missing values, and estimated intra-class correlation coefficients. It also incorporates a variant of k-nearest-neighbor imputation of missing values. Finally, we adapted an RNA-Seq approach and R package, scone, to select an appropriate normalization scheme for removing unwanted variation from metabolomics datasets.\n\nResultsUsing two metabolomics datasets that were generated in our laboratory from samples of human blood serum and neonatal blood spots, we compared our data-adaptive pipeline with a traditional filtering and normalization scheme. The data-adaptive approach outperformed the traditional pipeline in almost all metrics related to removal of unwanted variation and maintenance of biologically relevant signatures. The R code for running the data-adaptive pipeline is provided with an example dataset at https://github.com/courtneyschiffman/Data-adaptive-metabolomics.\n\nConclusionOur proposed data-adaptive pipeline is intuitive and effectively reduces technical noise from untargeted metabolomics datasets. It is particularly relevant for interrogation of biological phenomena in data derived from complex matrices associated with biospecimens.

bioinformatics↗