Biology subjects

Qin, S.

Publications and source records attributed to Qin, S..

At least 73 records · Page 4Linked to original sources

bioRxiv2023

Positive coping supports children's emotional wellness: Behavioral evidence and neuroendocrine mechanisms

A positive coping style is recognized as a stable disposition to foster emotional wellness and resilience, enabling an adaptive process of assessing and dealing with environmental challenges. Such an adaptive process is believed to rely on a nuanced interplay of the hippocampal system and the primary stress hormone cortisol activity. As a hallmark of diurnal cortisol rhythm, cortisol awakening response (CAR) is sensitive to upcoming stress and subserves the preparation of the hippocampal system for rapid behavioral adaption. Yet, little is known about how the hippocampal system and CAR contribute to the merit of positive coping on emotional wellness. By two studies, we investigate the effects of positive coping on childrens emotional wellness and CAR, as well as longitudinal changes in hippocampal-neocortical functional systems involved in emotional processing. Behaviorally, positive coping predicted better emotional regulation ability, but lower anxiety and lower response caution in emotional decision-making. At the endocrine and neurocognitive level, positive coping was associated with greater CAR, which further predicted higher connectivity of the hippocampus with ventrolateral prefrontal cortex (vlPFC) and stimulus-sensitive neocortex one year later. Furthermore, CAR mediated an indirect association between positive coping and longitudinal increases in hippocampal-neocortical connectivity. Positive coping and CAR together could account for the maturity of vlPFC through longitudinal changes in hippocampal-neocortical connectivity. Overall, our findings suggest a cognitive-neuroendocrinal framework in which positive coping shapes hippocampal-neocortical maturation via stress hormone response to support emotional wellness. SignificanceThe role of the hippocampal system in regulating stress response is well recognized, but its contribution to emotional well-being is not yet understood. Here we show that the protective effects of positive coping on emotional well-being are contingent on two factors: the cortisol awakening response (CAR), which is sensitive to upcoming stress, and hippocampal development. We found that positive coping practices promoted emotional wellness, enhanced emotional decision-making and increased CAR in young children. Longitudinal neuroimaging analysis revealed that positive coping-related CAR predicted greater hippocampal connectivity with stimulus-sensitive neocortex one year later. Importantly, CAR acted as a mediator of the promotive influence of positive coping on the longitudinal development of hippocampal-neocortical connectivity, which contributed to the maturity of prefrontal control systems. Our findings emphasize the importance of hippocampal-neocortical development in resilient coping and emotional wellness.

neuroscience↗

bioRxiv2023

Surf4 deficiency reduces intestinal lipid absorption and secretion and decreases metabolism in mice

BackgroundPostprandial dyslipidemia is a causative risk factor for cardiovascular disease. The majority of absorbed dietary lipids are packaged into chylomicron and then delivered to circulation. Previous studies showed that Surfeit4 (Surf4) mediates very low-density lipoprotein secretion from hepatocytes. Silencing hepatic Surf4 markedly reduces the development of atherosclerosis in different mouse models of atherosclerosis without causing hepatic steatosis. However, the role of Surf4 in chylomicron secretion is unknown. MethodsWe developed inducible intestinal-specific Surf4 knockdown mice (Surf4IKO) using Vil1Cre-ERT2 and Surf4flox mice. Metabolic cages were used to monitor mouse metabolism. Enzymatic kits were employed to measure serum and tissue lipid levels. The expression of target genes was detected by qRT-PCR and Western Blot. Transmission electron microscopy and radiolabeled oleic acid were used to assess the structure of enterocytes and intestinal lipid absorption and secretion, respectively. Proteomics was performed to determine changes in protein expression in serum and jejunum. ResultsSurf4IKO mice, especially male Surf4IKO mice, displayed significant body weight loss, increased mortality, and reduced metabolism. Surf4IKO mice exhibited lipid accumulation in enterocytes and impaired fat absorption and secretion. Lipid droplets and small lipid vacuoles were accumulated in the cytosol and the endoplasmic reticulum lumen of the enterocytes of Surf4IKO mice, respectively. Surf4 colocalized with apoB and co-immunoprecipitated with apoB48 in differentiated Caco-2 cells. Intestinal Surf4 deficiency also significantly reduced serum triglyceride, cholesterol and free fatty acid levels in mice. Proteomics data revealed that diverse pathways were altered in Surf4IKO mice. In addition, Surf4IKO mice had mild liver damage, decreased liver size and weight, and reduced hepatic triglyceride levels. ConclusionOur findings demonstrate that intestinal Surf4 plays an essential role in lipid absorption and chylomicron secretion and suggest that the therapeutic use of Surf4 inhibition requires highly cell/tissue-specific targeting. HighlightsO_LIIntestinal Surf4 deficiency reduces chylomicron secretion. C_LIO_LILack of intestinal Surf4 reduces absorption of dietary lipids. C_LIO_LISilencing intestinal Surf4 reduces serum lipid levels. C_LIO_LIIntestinal Surf4 deficiency leads to lipid accumulation in intestinal villi. C_LIO_LIIntestinal Surf4 is essential for dietary lipid absorption and secretion. C_LI

physiology↗

bioRxiv2023

Predicting the Sequence-Dependent Backbone Dynamics of Intrinsically Disordered Proteins

How the sequences of intrinsically disordered proteins (IDPs) code for functions is still an enigma. Dynamics, in particular residue-specific dynamics, holds crucial clues. Enormous efforts have been spent to characterize residue-specific dynamics of IDPs, mainly through NMR spin relaxation experiments. Here we present a sequence-based method, SeqDYN, for predicting residue-specific backbone dynamics of IDPs. SeqDYN employs a mathematical model with 21 parameters: one is a correlation length and 20 are the contributions of the amino acids to slow dynamics. Training on a set of 45 IDPs reveals aromatic, Arg, and long-branched aliphatic amino acids as the most active in slow dynamics whereas Gly and short polar amino acids as the least active. SeqDYN predictions not only provide an accurate and insightful characterization of sequence-dependent IDP dynamics but may also serve as indicators in a host of biophysical processes, including the propensities of IDP sequences to undergo phase separation.

biophysics↗

bioRxiv2023

Plant selection and ecological microhabitat drive domestications of shrub-associated microbiomes in a revegetated shrub ecosystem

Shrubs are used for revegetation of degraded dryland ecosystem worldwide and could recruit large numbers of microbes from the soil; however, the plant-associated microbiome assembly and the effect of plant introduction on the soil microbiomes are not fully understood. We detected shrub-associated microbes from five ecological microhabitats, including the leaves, litter, roots, rhizosphere, and root zone, across four xeric shrub plantations (Artemisia ordosica, Caragana korshinskii, Hedysarum mongolicum, and Salix psammophila). To detect the patterns of shrub-associated microbiome assembly, 16S and ITS2 rRNA gene sequencing was performed. PERMANOVA and differential abundance analysis demonstrated that changes in the bacterial and fungal communities were more dependent on the microhabitats rather than on the plant species, with distinct niche differentiation. Moreover, source tracking and nestedness analysis showed that shrub-associated bacteria were primarily derived from bulk soils and slightly pruned in different microhabitats; however, a similar pattern was not found for fungi. Furthermore, the surrounding zone of roots was a hotpot for microbial recruitments of revegetated shrubs. Null model analysis indicated that homogeneous selection of determinism dominated the bacterial communities, whereas dispersal limitation and undominated process of stochasticity drove the assembly of fungal communities. Our findings indicate that ecological microhabitat of revegetated shrublands was the main predictor of the bacterial and fungal compositional variances. This study will help advance our understanding of the mechanism underlying the plant-soil microbiome feedbacks during the initial plant-establishment period in a dryland ecosystem. Further, this work provides theoretical reference for establishment and sustainable management of shrublands in drylands.

microbiology↗

bioRxiv2022

Structural connectome architecture shapes the maturation of cortical morphology from childhood to adolescence

Cortical thinning is an important hallmark of the maturation of brain morphology during childhood and adolescence. However, the connectome-based wiring mechanism that underlies cortical maturation remains unclear. Using neuroimaging, connectome, transcriptome, and computational modeling, we mapped cortical thinning patterns primarily located in lateral frontal and parietal heteromodal nodes during childhood and adolescence, which is structurally constrained by white matter network architecture and is particularly represented using a network-based diffusion model. Furthermore, connectome-based constraints are regionally heterogeneous, with the largest constraints residing in frontoparietal nodes, and are associated with gene expression signatures of microstructural neurodevelopmental events. These results are highly reproducible while using another independent dataset. Our findings advance our understanding of network-level mechanisms and the associated genetic basis that underlies the maturational process of cortical morphology during childhood and adolescence.

neuroscience↗

bioRxiv2022

Phase separation as high-order catalyst

The long-distance communication between multiple cis-regulatory elements (CREs), the self-limiting size and lifetime of regulatory condensates, are two puzzling phenomena in biology. To reconcile these puzzles, we introduce the concept of higher-order catalysis into chromatin-mediated reactions. Essentially, multi-way contact between the CREs defines a transition state that is required for the downstream cascade of chemical reactions. The entropic penalty of chromatin reorganization sets a high activation barrier to enter this transition state. Phase separation of trans-acting agents induced by the CREs reduces this barrier and stabilizes the transition state via forming a regulatory condensate. The downstream reaction then pays back energy to dissolve the condensate and resets the agents to a metastable single-phase state. Accelerating the reactions without consuming agents or changing their state, the cycled phase transitions construct a higher-order catalyst or super-enzyme that is beyond the form of a single molecule. We discuss how chromatin employs such super-enzymes to catalyze higher-order reactions mediated by itself.

biophysics↗

bioRxiv2022

Efficient repair of human homozygous genetic mutation by CRISPR/Cas9 mediated interlocus gene conversion

DNA double-strand breaks (DSBs) induced by gene editing tools are primarily resolved either by non-homologous end joining (NHEJ) or homology-directed repair (HDR) using exogenous synthetic DNA templates. Repaired by error-prone NHEJ may lead to unexpected indels at the targeted site. In the case of most genetic disorders, HDR-mediated precise correction using an exogenous homologous sequence is ideal. However, the therapeutic application of HDR might be especially challenging given the requirement for the codelivery of exogenous DNA templates with toxicity into cells, and the low efficiency of HDR could also limit its clinical application. Here, we used hematopoietic stem cells (HSCs) with genetic mutations to cause {beta}-thalassemia in HBB coding regions and discovered that many cells are actually repaired by CRISPR/Cas9-mediated gene conversion (GC) independent of exogenous synthetic DNA templates. We show that pathogenic mutations in the HBB coding regions of HSCs can be repaired efficiently through CRISPR/GC using the paralog gene HBD as the internal template. Electroporations of Cas9 for ribonucleoprotein with sgRNA into haematopoietic stem and progenitor cells (HSPCs) with a variety of pathogenic gene mutations also resulted in effective conversion of mutations to normal wild-type sequences without exogenous DNA template. Moreover, the edited HSCs can repopulate the haematopoietic system and generate erythroid cells with a greatly reduced propensity for thalassemia after transplantations. Thus, CRISPR/GC, independent of exogenous DNA templates, holds great promise for gene therapy of genetic diseases.

genetics↗

bioRxiv2022

Comparative genomic analyses of Lactococcus garvieae isolated from bovine mastitis in China

Lactococcus garvieae is an emerging zoonotic pathogen, but there are few reports regarding bovine mastitis. The recent prevalence of L. garvieae poses an increasing disease threat and global public health risk. A total of 39 L. garvieae isolates were obtained from 2899 bovine clinical mastitis milk samples in 6 provinces of China from 2017 to 2021. Five clonal complexes were determined from 32 MLST types of L. garvieae; ST46 was the predominant sequence type and 13 novel MLST types were identified. All isolates were resistant to chloramphenicol and clindamycin, but susceptible to penicillin, ampicillin, amoxicillin-clavulanic acid, imipenem, ceftiofur, enrofloxacin, and marbofloxacin. Based on genomic analyses, L. garvieae had 6310 genes, including 1015, 3641 and 1654 core, accessory and unique genes. All isolates had virulence genes coding for collagenase, fibronectin-binding protein, Glyceraldehyde-3-phosphate dehydrogenase, superoxide dismutase and NADH oxidase. Most isolates had lsaD and mdtA AMR genes. Based on COG results, the functions of defense, transcription and replication, recombination and repair were enhanced in unique genes, whereas functions of translation, ribosomal structure and biogenesis were enhanced in core genes. The KEGG functional categories enriched in unique genes included human disease and membrane transport, whereas COG functional categories enriched in core genes included energy metabolism, nucleotide metabolism and translation. No gene was significantly associated with host specificity. In addition, core genome SNPs analysis suggested potential host adaptation of some isolates in several sequence types. Therefore, this study characterized L. garvieae isolated from mastitis and assessed host adaptation of L. garvieae to various hosts. IMPORTANCEThis study provides important insights on bovine mastitis key topic pathogen Lactococcus garvieae, which constitutes mastitis concerns. However, comprehensive genomic analyses of L. garvieae from dairy farms have not been performed. This study gives a detailed and comprehensive novel feature in L. garvieae, an important but poorly characterized bacterium, recovered in the past 5 years in 6 Chinese provinces. We documented diverse contributory genetic processes, including predominant sequence type ST46 and 13 novel MLST types. L. garvieae had 6310 genes, including 1015, 3641 and 1654 core, accessory and unique genes. All isolates had virulence genes coding for collagenase, fibronectin-binding protein, Glyceraldehyde-3-phosphate dehydrogenase, superoxide dismutase and NADH oxidase, and resistant to chloramphenicol and clindamycin. Most isolates had lsaD and mdtA antimicrobial resistance genes. No gene was significantly associated with host specificity. This is the first absolute quantification of L. garvieae isolated from mastitis and identified host adaptation of L. garvieae to various hosts.

microbiology↗

bioRxiv2022

Growth mindset promotes children's working memory performance through cortico-striatal interaction and fronto-parietal activation

Growth mindset--the belief that abilities are malleable through effort--drives motivation, action and achievement. Yet, the underlying mechanisms remain elusive, necessitating a unified framework that integrates cognitive, neural, and developmental processes. Leveraging longitudinal neuroimaging and computational modeling to reveal moment-to-moment decision responses and brain state dynamics during working memory (WM), we show that growth mindset enhances WM development from middle childhood to adolescence via nuanced cortico-striatal network dynamics that balance between brain state flexibility and stability. Behaviorally, children with higher growth mindset exhibited better WM performance both cross-sectionally and longitudinally, attributed to faster evidence accumulation during moment-to-moment information updating, especially under high task demands. Neurally, a higher growth mindset was associated with greater activation of the dorsal striatum, cingulo-opercular (action-mode), and fronto-parietal networks during WM, which further accounted for longitudinal WM improvement and latent evidence accumulation. Such cortico-striatal activation covaried with neurochemical mediators critical for motivation and executive functioning. Analyzing non-stationary network dynamics revealed that growth mindset optimized dynamical organization of cortico-striatal networks, with an activated state highly flexible to support moment-to-moment information updating and a deactivated state remaining stable across blocks to suppress irrelevant information. This suggests a balanced allocation of resources for accumulating evidence while suppressing noise during WM. Together, our findings support a neurocognitive framework in which growth mindset enhances WM development via nuanced orchestration of cortico-striatal networks to enable efficient dynamic computations and foster far-reaching cognitive development.

neuroscience↗

bioRxiv2022

Functional imaging and quantification of multi-neuronal olfactory responses in C. elegans

Many animals perceive odorant molecules by collecting information from ensembles of olfactory neurons. Each neuron employs receptors that are tuned to recognize certain odorant molecules by chemical binding affinity. Olfactory systems are able, in principle, to detect and discriminate diverse odorants by using combinatorial coding strategies. Multineuronal imaging with high-throughput stimulus delivery allows comprehensive measurement of ensemble-level sensory representations. We have used microfluidics and multineuronal imaging to study ensemble-level olfactory representations at the sensory periphery of the nematode C. elegans. The collective activity of nematode chemosensory neurons reveals high-dimensional representations of olfactory information across a broad space of odorant molecules. We reveal diverse tuning properties and dose-response curves across chemosensory neurons and across odorants. We describe the unique contribution of each sensory neuron to an ensemble-level code for volatile odorants. We also show how natural stimuli, a set of nematode pheromones, are encoded by the sensory periphery. The integrated activity of the C. elegans chemosensory neurons contains sufficient information to robustly encode the intensity and identity of diverse chemical stimuli.

neuroscience↗

bioRxiv2022

FIB-SEM analysis on three-dimensional structures of growing organelles in wild Chlorella pyrenoidosa cells

To clarify dynamic changes of organelle microstructures in Chlorella pyrenoidosa cells during photosynthetic growth with CO2 fixation, three-dimensional organelle microstructures in three growth periods of meristem, elongation and maturity were quantitatively determined and comprehensively reconstructed with focused ion beam scanning electron microscopy (FIB-SEM). The single round-pancake mitochondria in each cell split into a dumbbell and then into a circular ring, while barycenter distance of mitochondria to chloroplast and nucleus was reduced to 45.5% and 88.3% to strengthen energy transfer, respectively. The single pyrenoid consisting of a large part and another small part in each chloroplast gradually developed to a mature state in which the two parts were nearly equal in size. The nucleolus progressively became larger with euchromatin replication. The number of starch grains gradually increased, but average grain volume remained nearly unchanged.

cell biology↗

bioRxiv2022

A genetic model for in vivo proximity labeling of the mammalian secretome

Organ functions are highly specialized and interdependent. Secreted factors regulate organ development and mediate homeostasis through serum trafficking and inter-organ communication. Enzyme-catalyzed proximity labeling enables the identification of proteins within a specific cellular compartment. Here, we report a BirA*G3 mouse strain that enables CRE-dependent promiscuous biotinylation of proteins trafficking through the endoplasmic reticulum. When broadly activated throughout the mouse, widespread labeling of proteins was observed within the secretory pathway. Streptavidin affinity purification and peptide mapping by quantitative mass spectrometry (MS) proteomics revealed organ-specific secretory profiles and serum trafficking. As expected, secretory proteomes were highly enriched for signal peptide-containing proteins, highlighting both conventional and non-conventional secretory processes, and ectodomain shedding. Lower-abundance proteins with hormone-like properties were recovered and validated using orthogonal approaches. Hepatocyte-specific activation of BirA*G3 highlighted liver-specific biotinylated secretome profiles. The BirA*G3 mouse model demonstrates enhanced labeling efficiency and tissue specificity over viral transduction approaches and will facilitate a deeper understanding of secretory protein interplay in development, and healthy and diseased adult states.

cell biology↗

bioRxiv2022

Medial prefrontal-hippocampal concordance in child-parent dyads underlies children's psychological wellbeing

Family emotional climate is fundamental to childs emotional wellbeing and mental health. Negative family emotional climate may lead to heightened psychopathological symptoms via dysfunctional child-parent interactions. Single-brain paradigms have uncovered changes in brain systems and networks related to negative family environments, but how neurobiological reciprocity between child and parent brains is associated with childrens psychopathological symptoms remains unknown. In study1, we investigated the relationship between family emotional climate and childrens psychopathological symptoms in 395 child-parent dyads. In study2, using a naturalistic movie-watching functional magnetic imaging technique in a subsample of 100 children and parents, we investigate the neurobiological underpinnings of how family emotional climate is associated with childrens psychopathological symptoms through child-parent neural synchrony. Children from negative family emotional climate experienced more severe psychopathological symptoms. We revealed significantly higher inter-subject correlations in the dorsal and ventral portions of the medial prefrontal cortex (mPFC), and greater concordance of activity with widespread brain regions critical for socioemotional skills in child-parent than child-stranger dyads. Critically, negative family emotional climate was associated with decreased inter-subject functional correlation between the ventral mPFC and the hippocampus in child-parent dyads, which further accounted for higher childrens internalizing symptoms especially for anxious and depressed aspects. Family emotional climate might transmit into the brain of parent-child dyads, which may associate with child development outcomes. The present study identified that child-parent vmPFC-hippocampal circuitry is linked to childrens psychopathological symptoms. Our findings suggest a neurobiological mechanism of how negative family emotional climate affects childrens psychopathological symptoms through altered child-parent neural synchrony.

neuroscience↗

bioRxiv2022

LTD-inducing low frequency stimulation enhances p-Tau181 and p-Tau217 in an age-dependent manner in live rats

The progressive cognitive decline in Alzheimers disease (AD) patients correlates with the extent of tau pathology, in particular tau hyperphosphorylation, which is strongly age-associated. Although elevation of phosphorylated tau (p-Tau) on residues Thr181 (p-Tau181), Thr217 (p-Tau217), and Thr231 (p-Tau231) in cerebrospinal fluid or blood are recently proposed to be particularly sensitive markers of early AD, the generation of p-Tau during brain activity is poorly understood. A major form of synaptic plasticity, long-term depression (LTD), has recently been linked to the enhancement of tau phosphorylation. Here we show that low frequency stimulation (LFS), used to induce LTD, enhances p-Tau181 and p-Tau217 in an age-dependent manner in the hippocampus of live rats. In contrast, phosphorylation at residues Thr231, Ser202/Thr205, and Ser396 is less sensitive to LFS. Pharmacological antagonism of either NMDA or metabotropic glutamate 5 (mGluR5) receptors inhibits the elevation of both p-Tau181 and p-Tau217. Targeting ageing with a small molecule cognitive enhancer ISRIB (trans-isomer) prevents the enhancement of p-Tau by LFS in aged rats. Together, our data provide an in vivo means to uncover brain plasticity-related cellular and molecular processes of tau phosphorylation in health and ageing conditions.

neuroscience↗

bioRxiv2021

Non-rapid eye movement sleep and wake neurophysiology in schizophrenia

Motivated by the potential of objective neurophysiological markers to index thalamocortical function in patients with severe psychiatric illnesses, we comprehensively characterized key NREM sleep parameters across multiple domains, their interdependencies, and their relationship to waking event-related potentials and symptom severity. In 130 schizophrenia (SCZ) patients and controls, we confirmed a marked reduction in sleep spindle density in SCZ and extended these findings to show that only slow spindles predicted symptom severity, and that fast and slow spindle properties were largely uncorrelated. We also describe a novel measure of slow oscillation and spindle interaction that was attenuated in SCZ. The main sleep findings were replicated in a demographically distinct sample, and a joint model, based on multiple NREM components, predicted disease status in the replication cohort. Although also altered in patients, auditory event-related potentials elicited during wake were unrelated to NREM metrics. Consistent with a growing literature implicating thalamocortical dysfunction in SCZ, our characterization identifies independent NREM and wake EEG biomarkers that may index distinct aspects of SCZ pathophysiology and point to multiple neural mechanisms underlying disease heterogeneity. This study lays the groundwork for evaluating these neurophysiological markers, individually or in combination, to guide efforts at treatment and prevention as well as identifying individuals most likely to benefit from specific interventions.

neuroscience↗

bioRxiv2021

Coordinated drift of receptive fields during noisy representation learning

Long-term memories and learned behavior are conventionally associated with stable neuronal representations. However, recent experiments showed that neural population codes in many brain areas continuously change even when animals have fully learned and stably perform their tasks. This representational "drift" naturally leads to questions about its causes, dynamics, and functions. Here, we explore the hypothesis that neural representations optimize a representational objective with a degenerate solution space, and noisy synaptic updates drive the network to explore this (near-)optimal space causing representational drift. We illustrate this idea in simple, biologically plausible Hebbian/anti-Hebbian network models of representation learning, which optimize similarity matching objectives, and, when neural outputs are constrained to be nonnegative, learn localized receptive fields (RFs) that tile the stimulus manifold. We find that the drifting RFs of individual neurons can be characterized by a coordinated random walk, with the effective diffusion constants depending on various parameters such as learning rate, noise amplitude, and input statistics. Despite such drift, the representational similarity of population codes is stable over time. Our model recapitulates recent experimental observations in hippocampus and posterior parietal cortex, and makes testable predictions that can be probed in future experiments.

neuroscience↗

bioRxiv2021

Preferential interactions of a crowder protein with the specific binding site of a native protein complex

The crowded cellular environments provide ample opportunities for proteins to interact with bystander macromolecules, yet direct evidence, let alone residue-specific information, for such nonspecific binding is rare. Here, by combining NMR spectroscopy and atomistic modeling, we investigated how crowders influence the association equilibrium and kinetics of two protein partners, EIN and HPr. Ficoll-70 increases the EIN-HPr binding affinity whereas bovine serum albumin (BSA) decreases the affinity. The opposite effects of the two crowders are quantitatively explained by atomistic modeling, which shows that the stabilizing effect of Ficoll-70 arises from volume exclusion favoring the bound state. In contrast, the destabilizing effect of BSA arises from preferential soft interactions with the free state; notably, BSA has favorable electrostatic interactions with positively charged HPr residues within the EIN-binding site. Some of the residues from this site indeed experience significant chemical shift perturbation when titrated with BSA, while the relaxation rates of HPr backbone amides exhibit overall elevation. Furthermore, relaxation dispersion data indicate that Ficoll-70 and BSA both slow down the EIN-HPr association rate, but change the dissociate rate in opposite directions. The observations on kinetics are accounted for by two effects of the crowders: increasing the solution microviscosity and reshaping the EIN-HPr interaction energy surface. The kind of preferential interactions between BSA and HPr that leads to competition with EIN should be prevalent in cellular environments. Our NMR results and atomistic modeling provide benchmarks, at both qualitative and quantitative levels, for the effects of crowded cellular environments on protein-protein specific interactions. Significance StatementAlthough nonspecific binding of crowder macromolecules with functional proteins is likely prevalent in vivo, direct evidence is rare. Here we present NMR characterizations showing that bovine serum albumin preferentially interacts with a specific binding site on HPr, leading to competition with the latters partner EIN. The preferential interactions result in destabilization of the EIN-HPr native complex and speedup of its dissociation, contrary to expectations from excluded-volume and viscosity effects. Atomistic modeling of macromolecular crowding rationalizes the experimental observations, and provides qualitative and quantitative insight into the influences of the crowded cellular environment on protein-protein specific interactions. Our work also has implications for evolution, regarding how nonspecific binding can be either minimized or exploited for gaining new functions.

biophysics↗

bioRxiv2021

Development of Functional Connectome Gradients during Childhood and Adolescence

Connectome mapping studies have documented a principal primary-to-transmodal gradient in the adult brain network, capturing a functional spectrum which ranges from perception and action to abstract cognition. However, how this gradient pattern develops and whether its development is linked to cognitive growth, topological reorganization, and gene expression profiles remain largely unknown. Using longitudinal resting-state functional magnetic resonance imaging data from 305 children (ages 6-14), we describe substantial changes in the primary-to-transmodal gradient between childhood and adolescence, including emergence as the principal gradient, expansion of global topography, and focal tuning in primary and default-mode regions. These gradient changes are mediated by developmental changes in network integration and segregation, and are associated with abstract processing functions such as working memory and expression levels of calcium ion regulated exocytosis, synaptic transmission, and axon and synapse part related genes. Our findings have implications for understanding connectome maturation principles in normal development and developmental disorders. TeaserOur study reported the maturation of the core connectome gradient and its association with cognitions and genes expression.

neuroscience↗