Biology subjects

Jin, D.

Publications and source records attributed to Jin, D..

31 records · Page 2Linked to original sources

bioRxiv2021

Ratiometric 4Pi single molecule localization with optimal resolution and color assignment

4Pi single molecule localization microscopy (4Pi-SMLM) with two opposing objectives achieves sub-10 nm isotropic 3D resolution with as few as 250 photons collected by each objective. Here, we developed a new ratiometric multi-color imaging strategy for 4Pi-SMLM which employed the intrinsic multi-phase interference intensity without increasing the complexity of the system and achieved both optimal 3D resolution and color separation. By partially linking the photon parameters between channels with interference difference of {pi} during global fitting of the multi-channel 4Pi single molecule data, we showed on simulated data that the loss of the localization precision is minimal compared with the theoretical minimum uncertainty, the Cramer-Rao lower bound (CRLB).

biophysics↗

bioRxiv2021

Brain networks in human conscious visual perception

Consciousness is not explained by a single mechanism, rather it involves multiple specialized neural systems overlapping in space and time. We hypothesize that synergistic, large-scale subcortical and cortical attention and signal processing networks encode conscious experiences. To identify brain activity in conscious perception without overt report, we classified visual stimuli as perceived or not using eye measurements. Report-independent event-related potentials and functional magnetic resonance imaging (fMRI) signals both occurred at early times after stimuli. Direct recordings revealed a novel thalamic awareness potential linked to conscious visual perception based on report. fMRI showed thalamic and cortical detection, arousal, attentional salience, task-positive, and default mode networks were involved independent of overt report. These findings identify a specific sequence of neural mechanisms in human conscious visual perception. One-Sentence SummaryHuman conscious visual perception engages large-scale subcortical and cortical networks even without overt report.

neuroscience↗

bioRxiv2021

Renal Interstitial Cells Promote Nephron Regeneration by Secreting Prostaglandin E2

In organ regeneration, progrnitor and stem cells reside in their native microenvironment, which provides dynamic physical and chemical cues essential to their survival, proliferation and differentiation. However, what kind of cells provide a native microenvironment for renal progenitor cells has not been clarified. Here, single-cell sequencing of zebrafish kidney revealed that fabp10 was a marker of renal interstitial cells (RICs), and the Tg(fabp10a:GFP) transgenic line can specifically label RICs in zebrafish kidney. The formation of RICs and nephrons are closely accompanied during nephron regeneration. RICs form a network to wrap the renal progenitor cell aggregates. RICs in close contact with cell aggregates express cyclooxygenase 2 and secrete prostaglandin 2 (PGE2). Inhibiting PGE2 production prevented nephrogenesis by reducing the proliferation and differentiation of progenitor cell aggregates. PGE2 promoted maturation of the nephron by activating the WNT signaling pathway in progenitor cell aggregates in cooperation with Wnt4a. These findings suggest that RICs provide a necessary microenvironment for rapid nephrogenesis during nephron regeneration.

developmental biology↗

bioRxiv2020

Quantitatively Monitoring in situ Mitochondrial Thermal Dynamics by Upconversion Nanoparticles

Temperature dynamics reflect the physiological conditions of cells and organisms. Mitochondria regulates temperature dynamics in living cells, as they oxidize the respiratory substrates and synthesize ATP, with heat being released as a by-product of active metabolism. Here, we report an upconversion nanoparticles based thermometer that allows in situ thermal dynamics monitoring of mitochondria in living cells. We demonstrate that the upconversion nanothermometers can efficiently target mitochondria and the temperature responsive feature is independent of probe concentration and medium conditions. The relative sensing sensitivity of 3.2% K-1 in HeLa cells allows us to measure the mitochondrial temperature difference through the stimulations of high glucose, lipid, Ca2+ shock and the inhibitor of oxidative phosphorylation. Moreover, cells display distinct response time and thermal dynamic profiles under different stimulations, which highlights the potential applications of this thermometer to study in situ vital processes related to mitochondrial metabolism pathways and interactions between organelles.

cell biology↗

bioRxiv2020

Popularizing recombinant baculovirus-derived OneBac system for scaling-up production of all recombinant adeno-associated virus vector serotypes

Recombinant adeno-associated virus (rAAV) has been widely used as an efficient transgenic vector in biomedical research, as well as gene therapy. Serotype-associated transduction efficiency, tissue- or cell-type tropism and immunological profile are major considerations in the various applications of rAAVs. There are increasing needs for different serotypes of rAAV, either naturally isolated or artificially engineered. However, affordable and scalable production of a desired serotype of rAAV remains very difficult, especially for researchers lacking relevant experience. On the basis of our previously established single recombinant baculovirus expression vector (BEV)-derived OneBac system, we have optimized the process and expanded the rAAV production range to the full range of serotypes rAAV1-13. Firstly, the AAV Cap gene was optimized to translate by ribosome leaky scanning and the gene of interest (GOI) was cloned into the pFD/Cap-(ITR-GOI)-Rep2 shutte plasmid. Following the classical Bac-to-Bac method, sufficient BEV stock containing all rAAV packaging elements can be quickly obtained. Finally, we can repeatedly scale up production of rAAVs in one week by using a single BEV to infect suspension-cultured Sf9 cells. The rAAV1-13 show relatively high yields ranging from 5x104 to 4x105 VG/cell. More than 1x1015 VG purified rAAVs can be easily obtained from 5 L suspension-cultured Sf9 cells. As expected, rAAV serotypes 1-13 show different potencies for in vitro transduction and cell-type tropisms. In summary, the single BEV-derived OneBac system should prove popular for laboratory scaling-up production of any serotype of rAAV.

microbiology↗

bioRxiv2020

A Single Nucleotide Polymorphism assay sheds light on the extent and distribution of genetic diversity, population structure and functional basis of key traits in cultivated North American Cannabis

BackgroundThe taxonomic classification of the Cannabis genus has been delineated through three main types: sativa (long and less branched plant with long and narrow leaves), indica (short but highly branched plant with broader leaves) and ruderalis (wild type with short stature, less branching and small thick leaves). While still under discussion, particularly whether the genus is polytypic or monotypic, this broad classification reflects putative geographical origin of each group and putative chemotypic and pharmacology. MethodsHere we describe a thorough investigation of cannabis accessions using a set of 22 highly informative and polymorphic SNP markers associated with important traits such as cannabinoid and terpenoid expression as well as fibre and resin production. The assay offers insight into cannabis population structure, phylogenetic relationship, population genetics and correlation to secondary metabolite concentrations and demonstrate the utility of this assay for rapid, repeatable and cost-efficient genotyping of commercial and industrial cannabis accessions for use in product traceability, breeding programs, regulatory compliance and consumer education. ResultsThe main outcomes are the identification of 5 clusters in the sample set available, including industrial hemp, resin hemp which likely underwent a bottleneck to stabilize CBDA accumulation (Type II & III). THC resin (type I) make up the other three clusters with terpinolene (colloquial "sativa" or "NLD"), myrcene/pinene and myrcene/limonene (colloquial "indica", "BLD"), which also putatively harbour an active CBCAS. ConclusionThe functional basis of key traits is also discussed as recently enabled by the NCBI Cannabis sativa Annotation Release 100, allowing for hypothesis testing with regards to secondary metabolite production as well as other key traits of importance for adaptable and compliant large-scale seed production under the new US Domestic Hemp Production Program.

plant biology↗

bioRxiv2020

Escherichia coli σ38 promoters use two UP elements instead of a -35 element: resolution of a paradoxand discovery that σ38 transcribes ribosomal promoters

1In E. coli, one RNA polymerase (RNAP) transcribes all RNA species, and different regulons are transcribed by employing different sigma ({sigma}) factors. RNAP containing{sigma} 38 ({sigma}S) activates genes responding to stress conditions such as stationary phase. The structure of{sigma} 38 promoters has been controversial for more than two decades. To construct a model of{sigma} 38 promoters using information theory, we aligned proven transcriptional start sites to maximize the sequence information, in bits, and identified a -10 element similar to{sigma} 70 promoters. We could not align any -35 sequence logo; instead we found two patterns upstream of the -35 region. These patterns have dyad symmetry sequences and correspond to the location of UP elements in ribosomal RNA (rRNA) promoters. Additionally the UP element dyad symmetry suggests that the two polymerase subunits, which bind to the UPs, should have two-fold dyad axis of symmetry on the polymerase and this is indeed observed in an X-ray crystal structure. Curiously the CTDs should compete for overlapping UP elements. In vitro experiments confirm that{sigma} 38 recognizes the rrnB P1 promoter, requires a -10, UP elements and no -35. This clarifies the long-standing paradox of how{sigma} 38 promoters differ from those of{sigma} 70.

molecular biology↗

bioRxiv2019

Diurnal variations in the motility of algal populations

The motility of microalgae has been studied extensively, particularly in model microorganisms such as Chlamy-domonas reinhardtii. For this and other microalgal species, diurnal cycles are well-known to control the metabolism, growth and cell division. Diurnal variations, however, have been largely neglected in quantitative studies of motility. Here, we demonstrate using tracking microscopy how the motility statistics of C. reinhardtii are modulated by diurnal cycles. We discovered that the mean swimming speed is greater during the dark period of a diurnal cycle. From this measurement, using a hydrodynamic power balance, we conjecture that this is a result of the mean flagellar beat frequency being modulated by the flagellar ATP. Our measurements also quantify the diurnal variations of the orientational and gravitactic transport of C. reinhardtii. We discuss the implications of our frequency results in the context of cellular bioenergetics. Further, we explore the population-level consequences of diurnal variations of motility statistics by evaluating a prediction for how the gravitactic steady state changes with time during a diurnal cycle. SIGNIFICANCEWe report tracking microscopy measurements which demonstrate that the mean swimming speed of C. reinhardtii is significantly greater during the dark period of a diurnal cycle. Using hydrodynamic (low Reynolds number) power balance, we also inferred the mean flagellar beat frequency from the swimming speed, hypothesising that the observed variations in this frequency correlate with the diurnal regulation of flagellar ATP. Diurnal variations of the orientational and gravitactic transport of C. reinhardtii were also quantified and used in a continuum model to predict that, at the population scale, the steady state vertical distribution of C. reinhardtii is broader during the dark period. Our findings could have significant implications for microalgal biotechnologies, e.g. microalgal harvesting, and plankton migration in the ocean.

biophysics↗

bioRxiv2019

ALI-1, candidate gene of B1 locus, is associated with awn length and grain weight in common wheat

Awn plays a vital role in the photosynthesis, grain production and drought tolerance of common wheat; however, works on the systematic identification or cloning of genes controlling wheat awn length (AL) were seldom reported. Here, we conducted the Genome-wide association study (GWAS) in 364 wheat accessions and identified 25 loci involved in the AL, including dominant awn suppressors B1, B2 and four homologs of awn controlling genes in rice and barley. Furthermore, the B1 locus was mapped to a 125-kb physical interval harboring two genes on chromosome 5AL through map-based cloning. As the candidate gene for B1 locus, a C2H2 zinc finger gene Awn Length Inhibitor 1 (ALI-1) expressed predominantly in the developing spike of awnless individuals and suppresses downstream genes transcriptionally. ALI-1 reduces cytokinin content and simultaneously restrains cytokinin signal transduction, which leads to a stagnation of cell proliferation and reduction of cell number in awn. Noteworthily, ali-1 was the first awn controlling locus that observed increasing grain length in wheat, which is a valuable supplemental attribution of awn on grain weight besides photosynthesis. Thus, ALI-1 pleiotropically regulates awn and grain development, and this work provides a strategy to achieve improved grain yield and address future extreme climate.\n\nHighlightALI-1, candidate gene of awn suppressing B1 locus, associates with awn length and grain length, providing a reacquaint of the effect of wheat awn on grain production.

plant biology↗

bioRxiv2019

Phenological matching drives wheat pest range shift under climate change

Shifting geographical ranges of crop pests and pathogens in response to climate change pose a threat to food security (1, 2). The orange wheat blossom midge (Sitodiplosis mosellana Gehin) is responsible for significant yield losses in China (3), the worlds largest wheat producer. Here we report that rising temperatures in the North China Plain have resulted in a mean northward range shift of 3.3{degrees} (58.8 km per decade) from the 1950s to 2010s, which accelerated to 91.3 km per decade after 1985 when the highly toxic pesticide hexachlorocyclohexane (HCH) was banned (4). Phenological matching between wheat midge adult emergence and wheat heading in this new expanded range has resulted in greater damage to wheat production. Around $286.5 million worth of insecticides were applied to around 19 million hectares in an attempt to minimize wheat midge damage to crops between 1985 and 2016. Despite use of these pesticides, wheat midge caused losses of greater than 0.95 million metric tons of grain during this period. Our results demonstrate the potential for indirect negative impacts of climate change on crop production and food security, and constitute the first large scale example of plant pest range shift due to global warming.

ecology↗

bioRxiv2019

Imaging chromatin interactions at sub-kilobase resolution Via Tn5-FISH

There is increasing interest in understanding how the three-dimensional organization of the genome is regulated. Different strategies have been employed to identify chromatin interactions genome wide. However, due to the current limitations in resolving genomic contacts, visualization and validation of these genomic loci with sub-kilobase resolution remain the bottleneck for many years. Here, we describe Tn5 transposase-based Fluorescence in situ Hybridization (Tn5-FISH), a Polymerase Chain Reaction (PCR)-based, cost-effective imaging method, which achieved the co-localization of genomic loci with sub-kilobase resolution, to fine dissect genome architecture at sub-kilobase resolution and to verify chromatin interactions detected by Chromatin Configuration Capture (3C)-derivative methods. Especially, Tn5-FISH is very useful to verify short-range chromatin interactions inside of contact domain and Topologically Associated Domain (TAD). It also offers one powerful molecular diagnosis tool for clinical detection of cytogenetic changes in cancers.

cell biology↗

bioRxiv2018

Enrichment of short mutant cell-free DNA fragments enhanced detection of pancreatic cancer

Analysis of cell-free DNA (cfDNA) is promising for broad applications in clinical settings, but with significant bias towards late-stage cancers. Although recent studies have discussed the diverse and degraded nature of cfDNA molecules, little is known about its impact on the practice of cfDNA analysis. Here we reported a new targeted sequencing by combining single-strand library preparation and target capture (SLHC-seq). By applying the new technology in plasma cfDNA from pancreatic cancer patients, we achieved higher efficiency in analysis of mutations than previously reported using other detection assays. SLHC-seq rescued short or damaged cfDNA fragments along to increase the sensitivity and accuracy of circulating-tumor DNA detection. Most importantly, we found that the small mutant fragments are prevalent in early-stage patients, which provides strong evidence for fragment size-based early detection of pancreatic cancer. Collectively, the new pipeline enhanced our understanding of cfDNA biology and provide new insights for liquid biopsy.

cancer biology↗

bioRxiv2018

Generative adversarial network (GAN) enabled on-chip contact microscopy

We demonstrate a deep learning based contact imaging on a CMOS chip to achieve [~]1 m spatial resolution over a large field of view of [~]24 mm2. By using regular LED illumination, we acquire the single lower-resolution image of the objects placed approximate to the sensor with unit fringe magnification. For the raw contact-mode lens-free image, the pixel size of the sensor chip limits the spatial resolution. We apply a generative and adversarial network (GAN), a type of deep learning algorithm, to circumvent this limitation and effectively recover much higher resolution image of the objects, permitting sub-micron spatial resolution to be achieved across the entire sensor chip active area, which is also equivalent to the imaging field-of-view (24 mm2) due to unit magnification. This GAN-contact imaging approach eliminates the need of either lens or multi-frame acquisition, being very handy and cost-effective. We demonstrate the success of this approach by imaging the proliferation dynamics of cells directly cultured on the chip.

biophysics↗