Biology subjects

Jian, S.

Publications and source records attributed to Jian, S..

8 recordsLinked to original sources

bioRxiv2026

Reduced precipitation alters microbial availability and redistribution of rhizosphere carbon

Climate change intensifies grassland drying, which is predicted to decrease soil organic carbon (SOC) storage. Yet how reduced soil water affects the transport and processing of carbon in the rhizosphere -- a major source of SOC supporting microbial activities -- remains poorly resolved under field conditions. We traced living root-derived carbon (rhizodeposit C) into soils and microbes using {superscript 1}3CO2 labeling in a multi-year precipitation manipulation experiment in a California Mediterranean annual grassland dominated by Avena barbata. Under halved precipitation, season-averaged soil water content was 20% lower and soil matric potential more than threefold lower, without inducing detectable signs of plant stress. Quantitative stable isotope probing (qSIP) of rhizosphere microbial DNA revealed that up to 68% more bacterial and 13% more fungal taxa incorporated rhizodeposit C, and that microbial uptake of rhizodeposit C increased more over time under reduced precipitation, even as total microbial biomass and community composition were unchanged. {superscript 1}3C-informed co-occurrence networks of these consumers were larger and more connected under reduced precipitation. The surrounding soils contained less 13C, and modeled solute transport by soil water was 32-40% lower, implying that rhizodeposit C was retained and intensively processed nearer to roots rather than transported to the wider soil matrix. Our evidence supports that reduced precipitation concentrates rhizodeposit C near roots, increasing the number of distinct consumers and intensifying associations among them. This represents an overlooked mechanism linking precipitation reduction to rhizodeposit C cycling. These findings show that precipitation reduction may reshape rhizosphere C processing before apparent plant stress response, with potential consequences for the fate of rhizodeposit C in grassland soils.

microbiology↗

bioRxiv2024

SOFisher: Reinforcement Learning-Guided Experiment Designs for Spatial Omics

Spatial omics technologies enable the precise detection of proteins and RNAs at high spatial resolution. Designing spatial omics experiments requires careful consideration of "what" targets to measure and "where" to position the field of views (FOVs). Current FOV sampling strategies often involve acquiring densely sampled FOVs and stitching them together, which is time-consuming, resource-intensive, and sometimes impossible. To optimize FOV sampling strategies, we developed SOFisher, a reinforcement learning-based framework that harnesses the knowledge gained from the sequence of previously sampled FOVs to guide the selection of the next FOV position, to improve the efficiency of capturing more regions of interest. We rigorously evaluated SOFishers performance using comprehensive simulations based on real spatial datasets, and our results clearly demonstrated that SOFisher consistently outperformed the conventional approach across various metrics. SOFishers robustness and generalizability were further validated through cross-domain generalization tests and its adaptability to varying FOV sizes. On a real Alzheimers Disease (AD) dataset, SOFisher successfully guided the selection of FOVs containing neurofibrillary tangles and amyloid-{beta} plaques in both single and dual target tissue landmark scenarios. Remarkably, SOFisher-guided experiment design of spatial single-omics on limited tissue areas yielded insights into AD-related cell states, subtypes, and gene programs previously obtained through extensive spatial multi-omics experiments. SOFisher has the potential to revolutionize the experiment design of spatial biology.

bioinformatics↗

bioRxiv2023

Chromosome-level genome assembly for hucho bleekeri reveals the extraordinary tandem repeat proportions and its persistent population shrinkage

Salmonid fishes are globally renowned and valuable, with most members of the Salmonidae family living in seawater and exhibiting migratory behavior. In contrast, huchonid fishes (Hucho spp.and Brachymystax spp.), an ancient evolutionary branch within Salmoninae, are entirely landlocked. The Sichuan taimen (Hucho bleekeri Kimura) is a critically endangered fish that has attracted widespread concern and is one of eleven national first-level protected fishes in China. However, genome resources for all Hucho spp., including H. bleekeri, are scarce, and the genomic characteristics of this ancient evolutionary lineage remain unclear, hindering conservation biology efforts. Here, we present the first chromosome-level genome for the Sichuan taimen, with a final genome size of approximately 3.45 Gb across 44 chromosomes. The Sichuan taimen genome contains 44.15% tandem repetitive sequences, exceeding those of all sequenced salmonid fishes. We also identified 44 Ss4R homeologous block pairs in the assembled genome. Genome synteny analysis suggested a [~]5 fold tandem repeat expansion in the Sichuan taimen compared to the Salmonidae ancestor Northern pike. Phylogenetic analysis estimated the divergence time between huchonid and other Salmoninae fishes at approximately 33.29 million years ago (Mya). The divergence time between Siberia taimen and Sichuan taimen was estimated at around 2.29 Mya, with their effective population size declining from around 1 Mya. The genomic resource provided in this article will promote the protection of the Sichuan taimen and evolutionary genetics studies of salmonids.

genomics↗

bioRxiv2021

The genetic architecture of phenotypic diversity in the betta fish (Betta splendens)

The Betta fish displays a remarkable variety of phenotypes selected during domestication. However, the genetic basis underlying these traits remain largely unexplored. Here, we report a high-quality genome assembly and re-sequencing of 727 individuals representing diverse morphologies of the betta fish. We show that current breeds have a complex domestication history with extensive introgression with wild species. Using GWAS, we identify the genetic basis of multiple traits, including several coloration phenotypes, sex-determination which we map to DMRT1, and the long-fin phenotype which maps to KCNJ15. We identify a polygenic signal related to aggression with many similarities to human psychiatric traits, involving genes such as CACNB2 and DISC1. Our study provides a resource for developing the Betta fish as a genetic model for morphology and behavior in vertebrates.

genetics↗

bioRxiv2021

Cryo-EM Structure of Bacterioferritin Nanocages Provides Insight into the Bio-mineralization of Ferritins

Iron is an essential element involved in various metabolic processes. The ferritin family of proteins forms nanocage assembly and are involved in iron oxidation, storage and mineralization. Although several structures of human ferritin and bacterioferritin subunits have been resolved, there is still no complete structure that shows both the trapped Fe-biomineral cluster along with the nanocage. Furthermore, whereas the mechanism of iron trafficking has been explained using various approaches, an atomic-level description of the pathway and the biomineralization that occurs inside the cavity are lacking. Here, we report three cryo-EM structures of different states of the Streptomyces coelicolor bacterioferritin nanocage (i.e., apo, holo) at 3.4 [A] to 4.6 [A] resolution and the subunit crystal structure at 2.6 [A] resolution. The holo forms show different stages of Fe-biomineral accumulation inside the nanocage and suggest the possibility of a different Fe biomineral accumulation process. The cryo-EM map shows connections between the Fe-biomineral cluster and residues such as Thr157 and Lys42 from the protein shell, which are involved in iron transport. Mutation and truncation of the bacterioferritin residues involved in these connections can significantly reduce iron binding as compared with wild type bacterioferritin. Moreover, S. coelicolor bacterioferritin binds to various DNA fragments, similar to Dps (DNA-binding protein from starved cells) proteins. Collectively, our results represent a prototype for the ferritin nanocage, revealing insight into its biomineralization and the potential channel for ferritin-associated iron trafficking.

biophysics↗

bioRxiv2020

CGMTSA: An R package for continuous glucose monitoring time series data analysis

The R package CGMTSA was developed to facilitate investigations that examine the continuous glucose monitoring (CGM) data as a time series. Accordingly, novel time series functions were introduced to: 1) enable more accurate missing data imputation and outlier identification; 2) calculate recommended CGM metrics as well as key time series parameters; 3) plot interactive and 3D graphs that allow direct visualizations of temporal CGM data and time series model optimization. The software was designed to accommodate all popular CGM devices and support all common data processing steps.Competing Interest StatementThe authors have declared no competing interest.View Full Text

bioinformatics↗

bioRxiv2019

KIT ligand protects against both light-induced and genetic photoreceptor degeneration

Photoreceptor cell degeneration is a major cause of blindness and a considerable health burden during aging but effective therapeutic or preventive strategies have not so far become commercially available. Here we show in mouse models that signaling through the tyrosine kinase receptor KIT protects photoreceptor cells against both light-induced and inherited retinal degeneration. Upon light damage, photoreceptor cells upregulate Kit ligand (KITL) and activate KIT signaling, which in turn induces nuclear accumulation of the transcription factor NRF2 and stimulates the expression of the antioxidant gene Hmox1. Conversely, a viable Kit mutation promotes light-induced photoreceptor damage, which is reversed by experimental expression of Hmox1. Furthermore, overexpression of KITL from a viral AAV8 vector prevents photoreceptor cell death and partially restores retinal function after light damage or in genetic models of human retinitis pigmentosa. Hence, application of KITL may provide a novel therapeutic avenue for prevention or treatment of retinal degenerative diseases.

neuroscience↗

bioRxiv2017

NRT1.1-dependent NH4+ toxicity in Arabidopsis is associated with disturbed balance between NH4+ uptake and assimilation

A high concentration of a sole ammonium (NH4+) source in growth media is often toxic to plants. The nitrate transporter NRT1.1 is involved in plant NH4+ toxicity; however, its mechanism remains undefined. In this study, wild-type Arabidopsis (Col-0) and NRT1.1 mutants (chl1-1 and chl1-5) were grown hydroponically in NH4NO3 and (NH4)2SO4 media to evaluate NRT1.1 function in NH4+ stress responses. All plants grew normally in mixed N sources, but Col-0 displayed more chlorosis, and lower biomass and photosynthesis than the NRT1.1 mutants in the (NH4)2SO4 condition. Grafting experiments between Col-0 and chl1-5 further confirmed that NH4+ toxicity is NRT1.1-dependent. In (NH4)2SO4 medium, NRT1.1 facilitated the higher expression of NH4+ transporters, increasing NH4+ uptake. Additionally, glutamine synthetase (GS) and glutamate synthetase (GOGAT) in roots of Col-0 plants decreased and soluble sugar accumulated significantly, whereas pyruvate kinase (PK)-mediated glycolysis was not affected, all of which contributed to NH4+ accumulation. In contrast, the NRT1.1 mutants reduced NH4+ accumulation and enhanced NH4+ assimilation through glutamate dehydrogenase (GDH) and glutamate-oxaloacetate transamination (GOT) activity. In addition, the upregulation of genes involved in senescence in Col-0 plants treated with (NH4)2SO4 suggests that ethylene could be involved in NH4+ toxicity responses. Our results indicate that NH4+ toxicity is dependent on NRT1.1 in Arabidopsis, characterized by enhanced NH4+ accumulation and by perturbed NH4+ metabolism, which stimulated ethylene-induced plant senescence.\n\nHighlight: Nitrate transporter NRT1.1 enhances NH4+ accumulation, disturbs the NH4+ metabolism, and aggravates NH4+ toxicity in Arabidopsis when grown under sole NH4+ condition.

plant biology↗