Biology subjects

Chand, R.

Publications and source records attributed to Chand, R..

7 recordsLinked to original sources

bioRxiv2026

A Universal Free-Degree Orientation Extrusion Head Enables Conformal and Non-Planar Bio-Additive Manufacturing toward Adaptive and Future-Ready Bioprinting

Conventional extrusion-based 3D bioprinting encounters limitations in fabricating intricate tissue architectures due to fixed nozzle diameters and fixed deposition orientations. These constraints restrict conformal printing on curved or non-planar surfaces and often necessitate support-intensive fabrication strategies. This work introduces a mechanically simplified extrusion platform inspired by the swivel jet nozzle, featuring a free-degree-of-orientation extrusion head termed the universal extrusion head (Univ-Ex head), coupled with a modular nozzle architecture. The Univ-Ex head employs a swivel-like mechanical design that enables orientation freedom without external actuation in its current implementation, thereby minimizing mechanical complexity while supporting deposition on physiologically relevant, non-planar geometries. Multiple nozzle concepts were developed through comparative CAD iterations, with two representative geometries--a flat nozzle and a conical nozzle--selected for experimental validation. The platform is evaluated through parametric CAD design, stereolithography-printed prototypes, proof-of-concept extrusion experiments, and fluid dynamics simulations performed using FLOW-3D software. Numerical and experimental results demonstrate stable filament formation and clear diameter-dependent extrusion behavior, while simulations further confirm the feasibility of angled and non-planar deposition. A variable-diameter nozzle concept is proposed as a forward design direction to enable real-time adjustment of bioink flow rate and deposition resolution in principle; however, the present study intentionally validates the system using fixed-diameter nozzle variants to maintain stable numerical and experimental boundary conditions. A gear-integrated Univ-Ex head is also presented as a forward upgrade and demonstrated as a single-piece prototype. Collectively, this work establishes a scalable, hardware-focused pathway toward conformal bio-additive manufacturing. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=96 SRC="FIGDIR/small/734010v1_ufig1.gif" ALT="Figure 1"> View larger version (63K): org.highwire.dtl.DTLVardef@7a3213org.highwire.dtl.DTLVardef@6d9748org.highwire.dtl.DTLVardef@e733aforg.highwire.dtl.DTLVardef@f24a86_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2026

A rare human TNFAIP3 variant reveals how A20 abundance is regulated by TAX1BP1

Variants in TNFAIP3 (encoding A20) are among the most consistent non-MHC genetic associations with human autoimmune disease. Moreover, TNFAIP3 haploinsufficiency confers an autosomal dominant autoinflammatory and autoimmune disease. Whilst these findings strongly suggest that quantitative changes in A20 predispose to pathology, there is currently no evidence that post-transcriptional modifications regulate A20 abundance. We used human reverse genetics approach to investigate this question. From a cohort of patients with complex immune diseases, we identified an ultrarare hypomorphic TNFAIP3 variant (A20S254R) that is both hypomorphic and prone to phosphorylation. One of five carriers of this variant was distinguished by autoimmunity and an NF-kB gain-of-function transcriptional signature. A search for modifiers identified a variant in TAX1BP1 (p.Leu207Ile). We discovered that TAX1BP1 normally retrains A20 phosphorylation. Furthermore, TAX1BP1 preferentially binds phospho-A20, which explains the enhanced interaction between TAX1BP1L207I and A20S254R. A20 phosphorylation regulates its abundance, not by MALT1-mediated degradation, but probably via autophagy. Thus, while A20 phosphorylation has been implicated in A20 protease activity, an epistatic interaction between rare human genetic variants reveals how phosphorylation also regulates A20 abundance.

immunology↗

bioRxiv2026

Proteo-transcriptomics and morphometrics of teleost cardiac cells define regulatory networks and exercise-induced cardiomyocyte hypertrophy and hyperplasia

Zebrafish and medaka are powerful cardiovascular models, yet cellular and molecular investigations of adult heart cells have been constrained by suboptimal dissociation and characterization methods. To overcome these barriers, we developed a physiological-temperature workflow that generates high-yield, viable single-cell suspensions for FACS, imaging, and low-input molecular profiling. Using transgenic fluorescent reporters, we consistently isolate [~]6,000 cardiomyocytes per adult zebrafish ventricle and [~]12,000 from medaka, preserving cellular, structural, and molecular integrity. Single-cell morphometrics revealed cardiomyocyte heterogeneity and demonstrated that swimming exercise induces both hypertrophy and hyperplasia, while ventricular injury triggers expansion of regenerative gata4 cardiomyocytes. We integrated proteomics and RNA-seq from FACS-purified cells to construct cell-type-specific proteo-transcriptomic atlases. Functional enrichment, transcription factor, and network analyses identified protein hubs and regulatory circuits defining cardiomyocyte and endothelial cell identity. Our platform delivers cell-type-resolved molecular datasets of adult teleost cardiac cells, establishing a systems-level resource for heart regeneration research, cardiovascular disease modeling, and drug discovery. TeaserA robust workflow for isolation, FACS, imaging, and multi-omics profiling of cardiomyocytes and cardiac endothelial cells in fish. HIGHLIGHTSO_LITemperature-optimized dissociation and standardized FACS enable high-yield isolation of viable cardiac cells. C_LIO_LISingle-cell imaging uncovers morphological heterogeneity in adult ventricular cardiomyocytes. C_LIO_LISustained exercise induces both hypertrophy and hyperplasia of zebrafish cardiomyocytes. C_LIO_LIProteo-transcriptomics defines core molecular programs and interaction networks in cardiomyocytes and endothelial cells. C_LI

systems biology↗

bioRxiv2024

Location-Dependent Differences in Cardiac and Skeletal Muscle Dysfunction Associated With Truncating Titin (ttn.2) Variants

BackgroundTruncating variants (TTNtv) in the TTN gene, encoding the giant sarcomeric protein titin, cause a range of human cardiac and skeletal muscle disorders of varying penetrance and severity. The effects of variant location on clinical manifestations are incompletely understood. MethodsWe generated six zebrafish lines carrying tv in the ttn.2 gene at the Z-disk, I-band, A-band, and M-band titin regions. Expression of titin transcripts was evaluated using qPCR. Phenotype analysis was performed during embryonic development and in adult hearts. ResultsUsing location-specific primers, we found a significant reduction of Z-disk and I-band ttn.2 transcripts in all homozygous embryos but levels of A-band and M-band transcripts were reduced only in lines with truncations distal to the cronos promoter. Homozygous embryos uniformly died by 7-10 days post fertilization with marked impairment of cardiac morphology and function. Skeletal muscle motility and sarcomere organization were more disrupted in mutants with truncations distal to the cronos promoter compared to those proximal. The most C-terminal line (e232), which lacked only the titin kinase and M-band regions, differed from other lines, with homozygous embryos showing incorporation of truncated Ttn.2/Cronos protein and normal sarcomere assembly, but selective degradation of fast skeletal muscle sarcomeres. Heterozygous embryos were phenotypically indistinguishable from wild-type. High-frequency echocardiography in adult heterozygous fish showed reduced ventricular contraction under resting conditions in A-band mutants. Heterozygous Z-disk and I-band mutants had no significant baseline impairment but were unable to augment ventricular contraction in response to acute adrenaline exposure, indicating a lack of cardiac reserve. ConclusionsOur data suggest that cardiac and skeletal muscle dysfunction associated with truncating ttn.2 variants is influenced by age, variant location, and the amount of functional titin protein. The distinctive phenotype associated with distal C-terminal truncations may reflect different requirement for C-terminal titin for maintenance of fast, slow and cardiac muscle sarcomeres.

cell biology↗

bioRxiv2023

Heterologous Expression and Characterization of ToxA1 haplotype from India and its interaction with for Spot Blotch Susceptibility in spring wheat

BackgroundToxA, a necrotrophic effector protein, is present in the genome of fungal species like Parastagnospora nodorum, Pyrenophora tritici-repentis and Bipolaris sorokiniana. Tsn1 is the sensitivity gene in the host whose presence indicates more susceptibility to ToxA carrying pathogen, and ToxA-Tsn1 interaction follows an inverse gene-for-gene relationship. Methods and ResultsThe present study involved cloning and expressing the ToxA1 haplotype from B. sorokiniana. It was found that the amplicon exhibited an expected product size of 471 bp. Sequence analysis of the ToxA1 nucleotide sequence revealed the highest identity, 99.79%, with P. tritici-repentis. The protein expression analysis showed peak expression at 16.5kDa. Phylogenetic analysis of the ToxA1 sequence from all the Bipolaris isolates formed an independent clade along with P. tritici-repentis and diverged from P. nodorum. ToxA-Tsn1 interaction was studied in 18 wheat genotypes (11 Tsn1 and 7 tsn1) at both seedling and adult stages, validating the inverse gene-for-gene relationship, as the toxin activity was highest in the K68 genotype (Tsn1) and lowest in WAMI280 (tsn1). ConclusionThe study indicates that the haplotype ToxA1 is prevailing in the Indian population of B. sorokiniana. It would be desirable for wheat breeders to select genotypes with tsn1 locus for making wheat resistant to spot blotch.

plant biology↗

bioRxiv2019

Unveiling the transcriptome complexity of the High- and Low- Zinc & Iron accumulating Indian wheat (Triticum aestivum L.) cultivars

Development of Zinc (Zn), Iron (Fe) and other minerals rich grains along with various stress tolerance and susceptible (STR) wheat genotype, will help to reduce globally spread malnutrition problem. Current study deals with transcriptome profiling of 4 high- and 3 low- Zn & Fe accumulating wheat genotypes (HZFWGs) and (LZFWGs). Functional characterization of expressed and high and low specific genes, accompanied by metabolic pathways analysis reveals, phenylpropanoid biosynthesis, and other associated pathways are mainly participating in plant stress defense mechanism in both genotypes. Chlorophyll synthesis, Zn & Fe binding, metal ion transport, and ATP-Synthase coupled transport mechanism are highly active in HZFWGs while in LZFWGs ribosomal formation, biomolecules binding activities and secondary metabolite biosynthesis. Transcripts accountable for minerals uptake and purine metabolism in HZFWGs are highly enriched. Identified transcripts may be used for marker-assisted selection and breeding to develop minerals rich crops.

bioinformatics↗

bioRxiv2018

Direct immunosensing of avian influenza A virus in whole blood using hybrid nanocomposites

A sandwich-based electrochemical immunosensor was designed for detection of avian influenza virus (AIV) strains H5N1 and H4N6. This sensor was developed using gold-graphene nanocomposites, immobilized viral antibodies, and CdTe quantum dot electrochemical tagging. The nanocomposites were formed by the simultaneous reduction of a gold salt and graphene using hydroquinone as the reducing agent, thus producing non-spherical gold nanoparticles on graphene sheets. Viral antibodies were immobilized on nanocomposites and CdTe quantum dots through N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide and N-hydroxysuccinimide chemistry. Cyclic voltammetry studies were used to validate the detection of H5N1 surface protein and H4N6 inactivated virus. The immunosensor detected H5 protein in phosphate buffer solution (pH 7.4) with a limit of detection (LOD) of 10 fg/mL and a linear detection range was established for 10 ng/mL to 10 pg/mL. The biosensor detected H4N6 in three parts diluted whole chicken blood with a LOD of 1.28x10-7 hemagglutinating units (HAU). Commercial ELISA testing for H5N1 and H4N6 showed limits of detection of 10 ng/mL and 0.128 HAU, respectively. The sensor showed 106-fold increased detection of H4N6 virus in blood in comparison to its commercial ELISA kit counterpart. The developed immunosensor effectively change the way avian influenza is detected, monitored, and controlled; transforming time-consuming reactive methods, into rapid predictive technology.

bioengineering↗