Journal of Neurogenetics

Misexpression of the E3 ubiquitin ligase UBE3Ais thought to contribute to a range of neurological disorders. In the context of Dup15q syndrome, excess genomic copies of UBE3A is thought to contribute to the autism, muscle tone and spontaneous seizures characteristic of the disorder. In a Drosophila model of Dup 15q syndrome, it was recently shown glial-driven expression of the UBE3A ortholog dube3a led to a "bang-sensitive" phenotype, where mechanical shock triggers convulsions, suggesting glial dube3a expression contributes to hyperexcitability in flies. Here we directly compare the consequences of glial- and neuronal-driven dube3a expression on motor coordination and neuronal excitability in Drosophila. We utilized IowaFLI tracker and developed a hidden Markov Model to classify seizure-related immobilization. Both glial and neuronal driven dube3a expression led to clear motor phenotypes. However, only glial-driven dube3a expression displayed spontaneous immobilization events, that were exacerbated at high-temperature (38 {degrees}C). Using a tethered fly preparation we monitored flight muscle activity, we found glial-driven dube3a flies display spontaneous spike discharges which were bilaterally synchronized indicative of seizure activity. Neither control flies, nor neuronal-dube3a overexpressing flies display such firing patterns. Prior drug screen indicated bang-sensitivity in glial-driven dube3a expressing flies could be suppressed by certain 5-HT modulators. Consistent with this report, we found glial-driven dube3a flies fed the serotonin reuptake inhibitor vortioxetine and the 5HT2A antagonist ketanserin displayed reduced immobilization and spike bursting. Together these findings highlight the potential for glial pathophysiology to drive Dup15q syndrome-related seizure activity.

ObjectivesPolygenic hazard score (PHS) models can be used to predict the age-associated risk for complex diseases, including Alzheimers disease (AD). In this study, we present an improved PHS model for AD that incorporates a large number of genetic variants and demonstrates enhanced predictive accuracy for age of onset in European populations compared to alternative models. MethodsWe used the genotyped European Alzheimer & Dementia Biobank (EADB) sample (n=42,120) to develop and evaluate the performance of the PHS model. We developed a PHS model building on 720 genetic variants, including Apolipoprotein E (APOE) {varepsilon}2 and {varepsilon}4 alleles. We used Elastic Net-regularized Cox regression approach to develop the PHS model. ResultsThe new PHS model (EADB720) improved prediction accuracy compared to alternative models in European populations, with the Odds Ratio OR80/20 from the highest quintile of risk (80th risk percentile and above) to the lowest quintile of risk (20th risk percentile and below) varying between 5.10 and 13.15 within the range of age of onset from 65 - 85 years. Our model also improved risk stratification across {varepsilon}3/3 individuals of European ancestry (OR80/20 ranges from 1.95 to 3.52). It was also successfully validated in independent datasets (HUSK, DemGene and ADNI) by achieving OR80/20 up to 10.00 in each independent dataset. ConclusionOur EADB720 model significantly improves the accuracy of age-associated risk of AD across European populations (pval<0.03). Accurately predicting the age of onset of AD is of large clinical importance to implementing new AD medication and early intervention in clinical settings.

The dauer decision in Caenorhabditis elegans is a critical developmental decision that ensures survival under harsh environmental conditions. Factors such as temperature, food availability, and pheromone strongly influence the decision to enter and exit dauer. Traditional assays that assess the dauer decision are often confounded by the influence of pheromones from the population, which are often dynamic and highly variable. To mitigate this issue, we developed a simple, single-housing assay for dauer quantification that is compatible with optogenetics. We show that insulin-like peptides (ILPs) from ASJ and other neurons strongly influence the decision to exit dauer, and that ASJ activity can be manipulated with optogenetics to influence the dauer decision in a temporally precise manner.

Drosophila is widely used to study the pathological mechanisms of human diseases in vivo, including metabolic and neurological disorders. In these models, disease-induced alterations in locomotion and stress resistance are generally monitored in comparison to healthy control flies, such the white-eyed strain w1118, used as a reference for normal physiology and behavior. Here we compared two independent w1118 lines and found that they differed strikingly in their susceptibility to oxidative stress and nutrient starvation, and less markedly in their locomotor performance. Interestingly, modulating the gut microbiome by rearing these flies under axenic conditions increased oxidative stress resistance of the more susceptible, but not the more resistant line, while it had no effect on starvation resistance for both lines. We also found that the stress-sensitive line had higher levels of Clostridiales bacteria and of the intracellular endosymbiont Wolbachia in the gut microbiota, as well as lower expression levels of immune effectors (antimicrobial peptides and lysozymes) in the head and gut. Both lines nevertheless showed similar susceptibility to pathogenic bacterial infections. In a transgenic Parkinsons disease model, the stress-resistant background strongly attenuated the progressive locomotor defects induced by pan-neuronal expression of human mutant -synuclein, but intriguingly not when -synuclein expression was restricted to a subset of brain dopaminergic neurons in the protocerebral anterior medial (PAM) cluster. These results suggest that taking into account unapparent features of the reference lines could improve the reproducibility and consistency of neurodegenerative disease models in Drosophila.

The genetic tractability, well-mapped circuitry, and diverse behavioral repertoire of the nematode C. elegans make it an ideal model for physiological and behavioral studies. A wide range of methods has been developed for analyzing C. elegans behaviors, evolving with advances in technology such as videography and computer-assisted analysis. However, unlike organisms with distinct body features such as limbs and wings, the contour of C. elegans is rather uniform, posing unique challenges for automated analyses of C. elegans behavior. Here, we introduce LabGym--an open-source, artificial intelligence (AI)-based platform we recently developed--to the C. elegans research community. We trained deep learning models in LabGym capable of automatically categorizing and quantifying multiple user-defined parameters of worm locomotion behavior in multi-worm videos with high accuracy. Furthermore, we demonstrated their efficacy in quantifying locomotion changes in aging worms. Our work offers a cost-effective, user-accessible, and comprehensive approach to behavioral analysis in C. elegans.

Understanding how diverse cell types come together to form a functioning brain relies on the ability to specifically target these cells. This is often done using genetic tools such as the GAL4/UAS system in Drosophila melanogaster. Surprisingly, despite its extensive usage during studies of the ageing brain, detailed spatio-temporal characterisation of GAL4 driver lines in adult flies has been lacking. Here we show that three commonly used neuronal drivers (elav[C155]-GAL4, nSyb[R57C10]-GAL4 and ChAT-GAL4) and the commonly used glial driver repo-GAL4 all show rapid and pronounced decreases in activity over the first 1.5 weeks of adult life, with activity becoming undetectable in some regions after 30 days. In addition to an overall decrease in GAL4 activity over time, we found notable differences in spatial patterns, mostly occurring soon after eclosion. Although all lines showed these changes, the nSyb-GAL4 line exhibited the most consistent and stable expression patterns over ageing. Our findings suggest that gene transcription of key loci decreases in the aged brain, a finding broadly similar to previous work in mammalian brains. Our results also raise questions over past work on long-term expression of disease models in the brain, and stress the need to find better genetic tools for ageing studies.

BackgroundPsycho-affective symptoms and repetitive negative thinking (RNT) may increase Alzheimers disease (AD) risk. As sleep plays a key role in emotional regulation, we investigated both cross-sectional and longitudinal associations between sleep disturbances and psycho-affective health, according to amyloid-beta (A{beta}) status. MethodsOne hundred and thirty-four cognitively unimpaired older adults from the Age-Well interventional study (mean age = 68.8 {+/-} 3.8 years; 82 women; 37 A{beta}+ individuals) completed psycho-affective (Geriatric Depression Scale, State-Trait Anxiety Inventory), RNT (Rumination Response Scale-brooding, Penn State Worry Questionnaire) and sleep questionnaires (Pittsburgh Sleep Quality Index, Insomnia Severity Index). Wrist actigraphy (n=131; mean recording duration = 7.7 {+/-} 0.5 nights) provided objective measures of sleep fragmentation (sleep fragmentation index, wake time after sleep onset) and their night-to-night variability. Cross-sectional multiple linear regressions and longitudinal linear mixed-effects models (mean follow-up = 3.98 {+/-} 1.15 years) examined associations between sleep and psycho-affective symptoms, adjusting for age, sex, continuous positive airway pressure use, and the non-pharmacological intervention group (for longitudinal analyses). ResultsIn the whole cohort and in A{beta}- individuals, higher self-reported sleep difficulties and insomnia symptoms were cross-sectionally associated with greater anxiety, depression and RNT (all pFDR-corr<0.05). In A{beta}+ individuals, objective sleep fragmentation and instability were cross-sectionally associated with higher anxiety, depression and RNT. Longitudinally, higher baseline insomnia severity, mean sleep fragmentation, and night-to-night sleep instability predicted brooding worsening in A{beta}+ individuals only, while poorer perceived sleep quality predicted depressive symptoms worsening (all pFDR-corr<0.05). ConclusionsIn cognitively unimpaired older adults, associations between sleep disturbances and psycho-affective symptoms differ according to A{beta} status. In A{beta}+ individuals specifically, objective sleep fragmentation and instability are linked to psycho-affective vulnerability and brooding worsening over time. Sleep disturbances could thus represent early modifiable targets to mitigate psycho-affective symptomatology in older adults.

Spousal caregivers of individuals with Alzheimers disease and related dementias frequently experience elevated perceived stress, caregiver burden, and loneliness, which are associated with adverse health outcomes. Early identification is therefore critical for timely intervention. Existing approaches commonly rely on wearable sensor data and standardized psychological questionnaires, while recent multimodal methods aim to improve prediction by integrating behavioral and linguistic information. In this study, we explored three modality configurations, wearable-derived features, interview-based text, and their combination, to classify caregiver psychological risk using the Perceived Stress Scale (PSS), Zarit Burden Interview, and UCLA Loneliness Scale. We compared traditional machine learning models and large language models (LLMs) (Gemini 2.0, Llama 4, and GPT-4o) under psychometrician-centered and caregiver-centered prompting strategies. Traditional machine learning models performed better under multimodal settings, while LLMs achieved stronger performance with Interview-Only input. We further demonstrate that PSS was the most predictable construct and prompting strategies substantially influenced LLM performance.

Genetic defects in AP2M1, which encodes the -subunit of the adaptor protein complex 2 (AP-2) essential for clathrin-mediated endocytosis (CME), cause a rare form of developmental and epileptic encephalopathy (DEE). In this study, we modeled AP2M1-DEE in Drosophila melanogaster to gain deeper insights into the underlying disease mechanisms. Pan-neuronal knock-down of the Drosophila AP2M1 ortholog, AP-2{micro}, resulted in a consistent heat-sensitive paralysis phenotype and altered morphology in class IV dendritic arborization (c4da) neurons. Unexpectedly, affected flies were resistant to antiseizure medications and exhibited increased resistance to electrically induced seizures. A CRISPR-engineered fly line carrying the recurrent human disease variant p.Arg170Trp displayed a milder seizure resistance phenotype. While these findings contrast with the human phenotype, they align with previous studies on other CME-related genes in Drosophila. Our results suggest that hyperexcitability and seizures in AP2M1-DEE may stem from broader defects in neuronal development rather than direct synaptic dysfunction.

Sleep gets worse with age and is correlated with risk for disease and mortality. The possibility that poor sleep causes aging to accelerate has prompted interest in improving sleep to slow aging and prevent disease. However, the existing evidence on the link between poor sleep and accelerated aging is unclear. Here, we tested for correlation and causation between poor sleep and accelerated aging using five independent datasets of adults (total N > 64,000). We found strong evidence for a correlation between poor sleep and fast aging that is consistent across young, middle, and late adulthood and across aging biomarkers derived from different tissues and modalities. We found that this correlation is robust to the influence of chronic disease burden, but not to the influence of shared genetic and early environmental factors among twins. Finally, we found mixed evidence for a causal influence of poor sleep on accelerated aging using Mendelian randomization. Our findings indicate that the correlation between poor sleep and accelerated aging is highly robust; however, the claim that poor sleep causes aging to accelerate is not consistently supported.

Recent research evidence demonstrates that the inability to orient oneself and navigate space is an early indicator of Alzheimers Disease. The video game Sea Hero Quest (SHQ) was designed to assess the players navigation ability, and several research works analysed the SHQ data using simple metrics such as length and time of navigation paths. Expanding these analyses, we propose new performance metrics that capture the geometry of paths, and analyse datasets of more than 60,000 navigators. The metrics identify players who failed the navigation task, the dementia patients, and carriers of the at-risk allele of the Apolipoprotein-E [APOE]. Furthermore the metrics detect weak navigation ability when only a fraction of navigation paths are used, with superior performance to baseline methods. Our findings demonstrate that the proposed performance metrics pave the way to a comprehensive pre-clinical screening toolbox for Alzheimers Disease. TEASERWe propose geometric methods to capture decline in navigation ability from dementia.

The slow progression of Alzheimers disease (AD) poses a challenge for the rapid and individual quantification of early disease-driven cognitive decline. Here, we show that frequently administered remote and unsupervised digital cognitive assessments can detect cognitive decline within 30 weeks in early AD. The sample comprised 202 individuals (52-85 years old), who were cognitively unimpaired (CU) or had mild cognitive impairment (MCI). Participants self-administered remote tasks testing object and scene memory precision, associative memory, and familiarity-dependent memory. A short-term decline in the familiarity-dependent task was observed in all patients with an MCI diagnosis, while both the familiarity-dependent task and memory precision for objects were sensitive to decline in amyloid-positive MCI patients specifically. Change in the remote familiarity-dependent task was correlated with multi-year change on annual in-person neuropsychological assessments. In conclusion, frequent remote cognitive testing is a promising tool to feasibly capture and monitor subtle and short-term cognitive decline.

While astrocytes are known to be important for development and nourishment of the nervous system, the field is just beginning to explore how astrocytes respond to environmental stimuli. Using Caenorhabditis elegans and their astrocyte-equivalent, CEPsh, we asked whether astrocyte-like glia respond to odor exposure. We found one day-old adult C. elegans decrease hlh-17 promoter (CEPsh glia marker) mediated fluorescent expression when trained with an innately attractive odor butanone. Moreover, the olfactory training paradigm itself affects phlh-17 expression, but in a different way. This suggests astrocyte-like CEPsh glia can integrate environmental information to respond to changes in the environment, which enhances survival.

Parkinsons disease is a complex and multifactorial disorder, but how its biological and clinical complexity emerge from molecular to macroscopic brain interactions remains poorly understood. Here, we use a personalized multiscale generative brain model to characterize direct spatiotemporal links between genes and multimodal neuroimaging-derived biological factors in PD. We identified a set of genes modulating PD-associated longitudinal changes in dopamine transporter level, neuronal activity, dendrite density and tissue atrophy. Inter-individual heterogeneity in the gene-mediated biological mechanisms is associated with five distinct configurations of PD motor and non-motor symptoms. Although characterized by distinctive biological pathways, all the symptom configurations are associated with cell cycle processes. Notably, the protein-protein interaction networks underlying these configurations revealed distinct hub genes including MYC, CCNA2, CCDK1, SRC, STAT3 and PSMD4. We also uncovered the biological mechanisms associated with physical activities performance in PD, and observed that leisure and work activities are principally related to neurotypical cholesterol homeostasis and inflammatory response processes, respectively. Finally, patient-tailored in silico gene perturbations revealed a set of putative disease-modifying drugs with potential to effectively treat PD, most of which are associated with dopamine reuptake and anti-inflammation. Our study constitutes the first self-contained multiscale approach providing comprehensive insights into the complex multifactorial pathogenesis of PD, unravelling key biological modulators of physical and clinical deterioration, and serving as a blueprint for optimum drug selection at personalized level.

In several neurodegenerative diseases including Alzheimers disease (AD), tau, a microtubule-associated protein (MAP) enriched in the axon, becomes hyperphosphorylated, detaches from microtubules, redistributes to the somato-dendritic compartment and self-aggregates. The mechanisms leading to neuronal dysfunction and death by tau pathology remain to be fully elucidated. C. elegans has been successfully used by several groups including ours to identify mechanisms involved in neurodegeneration. We generated three strains, one overexpressing wild-type human tau (WT Tau), one a tau mutant mimicking hyperphosphorylation (hyperP Tau) and one preventing phosphorylation (hypoP Tau) in GABA motor neurons. A significant reduction of body size and egg laying was noted in these tau strains. Starting at day 1, we found that the worms overexpressing hyperP Tau were smaller than the N2 control strain and the worms either overexpressing WT Tau or hypoP Tau. Starting at day 5, the worms overexpressing WT Tau were smaller than control and the worms overexpressing hypoP Tau. Egg laying was reduced in both hyperP Tau and WT Tau worms. Survival was only decreased in WT Tau worms. Motility deficits were also observed. For age-dependent paralysis, a difference was noted between control and hyperP Tau. Swimming activity and speed were increased in hypoP Tau and decreased in hyperP Tau strains. Axonal integrity was altered in all tau strains. In the case of synaptic activity, at day 1, it was increased in the hypoP Tau strain and decreased in the hyperP Tau one. Collectively, our data revealed that overexpression of tau exerted neuronal and peripheral defects indicating that tau dysfunction could affect cell-cell communication.

When exposed to noxious thermal or mechanical stimuli, Drosophila melanogaster larvae will aZempt to escape by performing a stereotypical nocifensive rolling behavior. Here, we report the identification of a mutation in Drosophila that specifically alters the thermal nocifensive escape behaviors of larvae. We provide genetic, molecular, and histological evidence that this mutation maps to the FucTA gene, which encodes an -1,3-fucosyltransferase. Our results suggest that fucosylation is important for the thermal nociception rolling behavior of Drosophila larvae.

Molecular tool development in traditionally non-tractable animals opens new avenues to study gene functions in the relevant ecological context. Entomopathogenic nematodes (EPN) Steinernema and their symbiotic bacteria of Xenorhabdus spp are a valuable experimental system in the laboratory and are applicable in the field to promote agricultural productivity. The infective juvenile (IJ) stage of the nematode packages mutualistic symbiotic bacteria in the intestinal pocket and invades insects that are agricultural pests. The lack of consistent and heritable genetics tools in EPN targeted mutagenesis severely restricted the study of molecular mechanisms underlying both parasitic and mutualistic interactions. Here, I report a protocol for CRISPR-Cas9 based genome-editing that is successful in two EPN species, S. carpocapsae and S. hermaphroditum. I adapted a gonadal microinjection technique in S. carpocapsae, which created on-target modifications of a homologue Sc-dpy-10 (cuticular collagen) by homology-directed repair. A similar delivery approach was used to introduce various alleles in S. hermaphroditum including Sh-dpy-10 and Sh-unc-22 (a muscle gene), resulting in visible and heritable phenotypes of dumpy and twitching, respectively. Using conditionally dominant alleles of Sh-unc-22 as a co-CRISPR marker, I successfully modified a second locus encoding Sh-Daf-22 (a homologue of human sterol carrier protein SCPx), predicted to function as a core enzyme in the biosynthesis of nematode pheromone that is required for IJ development. As a proof of concept, Sh-daf-22 null mutant showed IJ developmental defects in vivo (in insecta). This research demonstrates that Steinernema spp are highly tractable for targeted mutagenesis and has great potential in the study of gene functions under controlled laboratory conditions within the relevant context of its ecological niche.

BackgroundA growing body of research has found that neural representations of task stimuli are less distinctive in older adults relative to younger adults, a phenomenon known as age-related neural dedifferentiation. The original funding period of the Michigan Neural Distinctiveness (MiND) study aimed to investigate the scope, causes, and consequences of neural dedifferentiation. We recruited a sample of healthy older adults (aged 65+ years) and younger adults (aged 18-29) and administered fMRI (to measure neural distinctiveness), MRS (to measure GABA), and substantial behavioral testing (to measure cognitive, motor, and sensory functions). We found that neural distinctiveness was lower in older vs. younger adults, that reduced GABA was associated with this neural dedifferentiation, and that behavioral performance was associated with both neural dedifferentiation and reduced GABA. In this current paper, we describe the rationale and methods for the second phase of the MiND study, in which we: 1) investigate age-related trajectories of change in neural distinctiveness, GABA, and behavior longitudinally; and 2) explore how neural differentiation is related to Alzheimers disease pathology. MethodsIn the longitudinal aim, we are re-contacting participants from the original MiND funding period. We aim to test participants at two additional time points approximately 3-5 years apart using the same assessments (fMRI, MRS, and behavioral tests). We plan to have approximately 150 participants with two time points and 100 participants with three time points. We will also recruit new participants who will be tested twice, approximately 3-5 years apart in order to further increase our sample size and power. We predict to have approximately 250 new participants with one time point. We will then test whether neural distinctiveness, GABA, and behavioral performance decline longitudinally with age. To explore neural dedifferentiation in Alzheimers disease pathology, we plan to recruit 100 MCI participants who are already undergoing PET imaging to determine amyloid beta and tau burden. These patients are then completing our fMRI, MRS and behavioral testing sessions so that we can examine associations between Alzheimers pathology and our measures of neural distinctiveness, GABA, and behavior. DiscussionThis line of research has the potential to lead to new insights into how aging affects the mind. In particular, it could shed light on the role that neural dedifferentiation, GABA, and Alzheimers disease pathology play in age-related behavioral declines. Trial RegistrationThis study was registered with the ISRCTN registry on November 11, 2024. The registration number is ISRCTN16528440.

INTRODUCTIONLipid abnormalities have been observed in brain, CSF, and blood in association with late-onset Alzheimers disease (LOAD). It is unknown which abnormalities are precursors to LOAD and which are concomitants of illness or its treatment. Inherent abnormalities can be identified in induced pluripotent stem cell (iPSC)-derived neural lines. METHODSiPSC lines of patients with LOAD or healthy individuals were differentiated to astrocytes. Lipidomics analyses were performed on whole cell and mitochondrial extracts. RESULTSLarge reductions in cholesterol esters (CE) and imbalances in fatty acids (FA) were observed in LOAD-associated cells or their mitochondria. There were only modest differences in other lipid classes, including membrane structural lipids. DISCUSSIONThe findings identify abnormalities in CE and FA as likely precursors to LOAD. These differences implicate mechanisms contributing to disease pathogenesis. Further study may lead to early interventions to prevent or delay LOAD.

Drosophila adult and larvae exhibit sophisticated behaviors that are widely used in development, synaptic transmission, sensory physiology, and learning and memory research. Many of these behaviors depend on locomotion, the ability of an animal to move. However, the statistical analysis of locomotion is not trivial. Here we use an open-source Fiji plugin TrackMate to track the locomotion of Drosophila adults and larvae. We build optimal experimental setups to rapidly process recordings by Fiji and analyze by TrackMate. We also provide tips for analyzing non-optimal recordings. TrackMate extracts the X and Y positions of an animal on each frame of an image sequence or a video. This information allows for generating moving trajectories, calculating moving distances, and determining preference indices in two-choice assays. Notably, this free-cost analysis method does not require programming skills. Summary statementThis study uses an open-source Fiji plugin TrackMate to computationally analyze Drosophila adult and larval behavioral assays, which does not require programming skills.