Biology subjects

Zhang, R.

Publications and source records attributed to Zhang, R..

At least 559 records · Page 31Linked to original sources

bioRxiv2020

Alterations of human lung and gut microbiome in non-small cell lung carcinomas and distant metastasis

BackgroundNon-small cell lung cancer (NSCLC) is the leading cause of cancer-related deaths worldwide. Although dysbiosis of lung and gut microbiota have been associated with NSCLC, their relative contributions are unclear; in addition, their roles in distant metastasis (DM) are still illusive. ResultsWe surveyed the fecal and sputum (as a proxy for lung) microbiota in healthy controls and NSCLC patients of various stages, and found significant perturbations of gut- and sputum-microbiota in patients with NSCLC and DM. Machine-learning models combining both microbiota (mixed models) performed better than either dataset in patient stratification, with the highest area under the curve (AUC) value of 0.842. Sputum-microbiota contributed more than the gut in the mixed models; in addition, sputum-only models performed similarly to the mixed models in most cases. Several microbial-biomarkers were shared by both microbiota, indicating their similar roles at distinct body sites. Microbial-biomarkers of distinct disease stages were mostly shared, suggesting biomarkers for distant metastasis could be acquired early. Furthermore, Pseudomonas aeruginosa, a species previously associated with wound infections, was significantly more abundant in brain metastasis, indicating distinct types of DMs could have different microbial-biomarkers. ConclusionOur results indicate that alterations of sputum-microbiota have stronger relationships with NSCLC and distant metastasis than the gut, and strongly support the feasibility of metagenome-based non-invasive disease diagnosis and risk evaluation.

microbiology↗

bioRxiv2020

Dual-localized enzymatic components that constitute the mitochondrial and plastidial fatty acid synthase systems

We report the identification and characterization of genes encoding three enzymes that are shared between the mitochondrial and plastidial-localized Type II fatty acid synthase systems (mtFAS and ptFAS, respectively). Two of these enzymes, {beta}-ketoacyl-ACP reductase (pt/mtKR) and enoyl-ACP reductase (pt/mtER) catalyze two of the reactions that constitute the core, 4-reaction cycle of the FAS system, which iteratively elongate the acyl-chain by 2-carbon atoms per cycle. The third enzyme, malonyl-CoA:ACP transacylase (pt/mtMCAT) catalyzes the reaction that loads the mtFAS system with substrate, by malonylating the phosphopantetheinyl cofactor of acyl carrier protein (ACP). GFP-transgenic experiments determined the dual localization of these enzymes, which were validated by the characterization of mutant alleles, which were transgenically rescued by transgenes that were singularly retargeted to either plastids or mitochondria. The singular retargeting of these proteins to plastids rescued the embryo-lethality associated with disruption of the essential ptFAS system, but these rescued plants display phenotypes typical of the lack of mtFAS function. Specifically, these phenotypes include reduced lipoylation of the H subunit of the glycine decarboxylase complex, the hyperaccumulation of glycine, and reduced growth; all these traits are reversible by growing these plants in an elevated CO2 atmosphere, which suppresses mtFAS-associated, photorespiration-dependent chemotypes.

biochemistry↗

bioRxiv2019

QTL Mapping and integration as well as candidate gene prediction for branch number in soybean

Branch number is an important factor that affects crop plant architecture and yield in soybean. With the aim of elucidating the genetic basis of branch number, we identified 10 consensus quantitative trait loci (QTLs) through preliminary mapping, which were on chromosome A1, B2, C1, C2, D1a, D1b, F, L and N, explained 0.3-33.3% of the phenotypic variance. Of these, three QTLs were identical to previously identified ones, whereas the other seven were novel. In addition, one major QTL-qBN.C2 (R2=33.3%) was detected in all three environments and another new major QTL-qBN.N (R2=19.6%) was detected in two environments (Taiyuan 2017 and Taiyuan 2018), but only in Taiyuan. Thus, the QTL x environment interaction analysis confirmed that QTL-qBN.N was strongly affected by the environment. We compared the physical positions of the QTL intervals of the candidate genes potentially involved in branching development, and five orthologous genes were ultimately selected and related to the establishment of axillae meristem organization and lateral organs, qBN.A1 (SoyZH13_05G177000.m1), qBN.C2 (SoyZH13_06G176500.m1, SoyZH13_06G185600.m1), and qBN.D1b-1 (SoyZH13_02G035400.m1, SoyZH13_02G070000.m3). The results of our study reveal a complex and relatively complete genetic architecture and can serve as a basis for the positional gene cloning of branch number in soybean.

genetics↗

bioRxiv2019

Phase separation-mediated formation of condensed GIT/PIX enzyme complex module for compartmentalized signaling

Cells compartmentalize enzymes for broad physiological functions such as efficient metabolic reactions and spatiotemporally controlled signaling. A given enzyme or enzyme complex can participate in multiple cellular processes in response to different signal inputs by forming different cellular compartments. Here, we demonstrate that association of GIT1 and {beta}-Pix, a pair of GTPase regulatory enzymes involved in diverse cellular processes, leads to autonomous condensation of the complex via phase separation without additional scaffolding molecules. The atomic structure of the GIT/PIX complex reveals the molecular basis governing the phase separation-mediated condensation of the GIT1/{beta}-Pix complex. Importantly, the GIT1/{beta}-Pix condensates can function as a versatile modular membrane-less organelle- like structure for distinct cellular compartmentalization by binding to upstream proteins such as Paxillin in focal adhesions, Shank3 in neuronal synapses, and Scribble in cellular junctions. Thus, phase separation-mediated formation of condensed enzyme complexes provides a powerful way of dynamically concentrating limited amounts of cooperating enzymes to specific cellular compartments for optimal signaling.

cell biology↗

bioRxiv2019

Novel pelagiphages prevail in the ocean

Viruses play a key role in biogeochemical cycling and host mortality, metabolism, physiology and evolution in the ocean. Viruses that infect the globally abundant marine SAR11 bacteria (pelagiphages) were reported to be an important component of the marine viral community. In this study, ten pelagiphages that infect three different Pelagibacter strains were isolated from various geographical locations and were genomically characterized. All ten pelagiphages are novel, representing four new lineages of the Podoviridae family. Although they share limited homology with cultured phage isolates, they are all closely related to some environmental viral fragments. Two HTVC023P-type pelagiphages are shown to be related to the abundant VC_6 and VC_8 viral populations of the Global Oceans Viromes (GOV) datasets. Interestingly, HTVC103P-type pelagiphages contain a structural module similar to that in SAR116 phage HMO-2011. Three HTVC111P-type pelagiphages and HTVC106P are also novel and related to GOV VC_41 and VC_67 viral populations, respectively. Remarkably, these pelagiphage represented phage groups are all globally distributed and predominant. Half of the top ten most abundant known marine phage groups are represented by pelagiphages. The HTVC023P-type group is the most abundant known viral group, exceeding the abundance of HTVC010P-type and HMO-2011-type groups. Furthermore, the HTVC023P-type group is also abundant throughout the water column. Altogether, this study has greatly broadened our understanding of pelagiphages regarding their genetic diversity, phage-host interactions and the distribution pattern. Availability of these newly isolated pelagiphages and their genome sequences will allow us to further explore their phage-host interactions and ecological strategies.

ecology↗

bioRxiv2019

TDM: a temporal decomposition method for removing venous effects from task-based fMRI

Most functional magnetic resonance imaging (fMRI) is conducted with gradient-echo pulse sequences. Although this yields high sensitivity to blood oxygenation level dependent (BOLD) signals, gradient-echo acquisitions are heavily influenced by venous effects which limit the ultimate spatial resolution and spatial accuracy of fMRI. While alternative acquisition methods such as spin-echo can be used to mitigate venous effects, these methods lead to serious reductions in signal-to-noise ratio and spatial coverage, and are difficult to implement without leakage of undesirable non-spin-echo effects into the data. Moreover, analysis heuristics such as masking veins or sampling inner cortical depths using high-resolution fMRI may be helpful, but sacrifice information from many parts of the brain. Here, we describe a new analysis method that is compatible with conventional gradient-echo acquisition and provides venous-free response estimates throughout the entire imaged volume. The method involves fitting a low-dimensional manifold characterizing variation in response timecourses observed in a given dataset, and then using identified early and late timecourses as basis functions for decomposing responses into components related to the microvasculature (capillaries and small venules) and the macrovasculature (veins), respectively. We show that this Temporal Decomposition through Manifold Fitting (TDM) method is robust, consistently deriving meaningful timecourses in individual fMRI scan sessions. Moreover, we show that by removing late components, TDM substantially reduces the superficial cortical depth bias present in gradient-echo BOLD responses and eliminates artifacts in cortical activity maps. TDM is general: it can be applied to any task-based fMRI experiment, can be used with standard- or high-resolution fMRI acquisitions, and can even be used to remove residual venous effects from specialized acquisition methods like spin-echo. We suggest that TDM is a powerful method that improves the spatial accuracy of fMRI and provides insight into the origins of the BOLD signal.

neuroscience↗

bioRxiv2019

Functional dissection of basal ganglia inhibitory input onto SNc dopaminergic neurons

Substania nigra (SNc) dopaminergic neurons show a pause-rebound firing pattern in response to aversive events. Because these neurons integrate information from predominately inhibitory brain areas, it is important to determine which inputs functionally inhibit the dopamine neurons and whether this pause-rebound firing pattern can be produced by a solely inhibitory input. Here, we functionally map genetically-defined inhibitory projections from the dorsal striatum (striosome and matrix) and globus pallidus (GPe; parvalbumin and Lhx6) onto SNc neurons. We find that GPe and striosomal inputs both pause firing in SNc neurons, but rebound firing only occurs after inhibition from striosomes. Indeed, we find that striosomes are synaptically optimized to produce rebound and preferentially inhibit a subpopulation of ventral, intrinsically rebound-ready SNc dopaminergic neurons on their reticulata dendrites. Therefore, we describe a self-contained dendrite-specific striatonigral circuit that can produce pause-rebound firing in the absence of excitatory input.

neuroscience↗

bioRxiv2019

Structural Insights into Negative Cooperativity between Gemin2 and RNA in Sm-class snRNP Assembly

Sm-class ribonucleoprotein particles (RNPs) are ring-shaped structures (Sm cores) formed by Sm hetero-heptamer around a segment of RNA, containing a nonameric oligoribonucleotide, PuAUUUNUGPu, followed by a stem-loop, and are basic structural modules critical for stability and functions of spliceosomal, telomerase and U7 RNPs. In the chaperones-assisted Sm core assembly, Gemin2 of the SMN complex, not only binds SmD1/D2/F/E/G (5Sm), but also serves as a checkpoint via a negative cooperativity mechanism uncovered in our recent study: Gemin2 constricts the horseshoe-shaped 5Sm in a narrow conformation from outside, preventing non-cognate RNA and SmD3/B from joining; only cognate RNA can bind inside 5Sm and widen 5Sm, dissociating Gemin2 from 5Sm and recruiting SmD3/B. However, the structural mechanics is unknown. Here I describe a coordinate-improved structure of 5Sm bound by Gemin2/SMN. Moreover, via new analysis, comparison of this structure with those of newly coordinate-improved Sm cores reveals the negative cooperativity mechanism between Gemin2 and RNA in binding 5Sm at atomic resolution level and provides structural insights into RNA selection and Gemin2s release in Sm core assembly. Finally, implications in the evolution of the Sm-core assembly chaperoning machinery and the neurodegenerative disease spinal muscular atrophy caused by SMN deficiency are discussed.

molecular biology↗

bioRxiv2019

TGS-GapCloser: fast and accurately passing through the Bermuda in large genome using error-prone third-generation long reads

The completeness and accuracy of genome assemblies determine the quality of subsequent bioinformatics analysis. Despite benefiting from the medium/long-range information of third-generation sequencing techniques, current gap-closing tools to enhance assemblies suffer multi-alignments and high error rates, resulting in huge time and money costs.\n\nWe developed a software tool, TGS-GapCloser that uses the low depth (>=10X) single molecule sequencing long reads without any error correction to close gaps. The algorithm distinguishes gap regions from the alignments of long reads against original scaffolds, corrects only the candidate regions, and assigns the best sequences to each gap. We demonstrate that TGS-GapCloser improves the contig N50 value of draft assembly by 25-fold on average, updating above 90% gaps with 93.96% positive predictive value. Despite of high error rate of raw long reads, improved assemblies archive Q50 (99.999%) single-base accuracy with only 11.8% decrement to inputs. Besides it could complete more gaps, and is also [~]29-fold faster than mainstream gap-closing tools. BUSCO analysis revealed that 3.4%-13.1% more expected genes were complete. TGS-GapCloser also shows its power to fill gaps for ultra large genome assembly of ginkgo ([~]12Gb) with 71.6% of gaps closed. The validation of inserted or merged gap sequences was conducted with NGS reads and reference genomes, respectively. The updated genome assemblies may promote the gene annotation, structure variant calling and thus improving the downstream analysis of ontogeny, phylogeny, and evolution.

bioinformatics↗

bioRxiv2019

Enzalutamide-induced PTH1R-mediated TGFBR2 decrease in osteoblasts contributes to resistance in bone-metastatic prostate cancer

Over 80% of prostate cancer (PCa) patients in the United States die with bone metastases. Second-line hormonal therapies, such as enzalutamide, improve overall survival in about 50% of patients with bone metastases, but almost all responsive patients eventually develop enzalutamide resistance. Our study showed that although enzalutamide significantly inhibited the tumor growth of subcutaneously or orthotopically grafted PCa C4-2B cells, it had no effect on the bone lesion development when C4-2B tumors were grafted in the bone, suggesting a crucial role of the microenvironment in enzalutamide resistance in PCa bone metastasis. We found that enzalutamide significantly decreased the amount of the TGFBR2 (TGF-{beta} type II receptor) in osteoblasts, both in vitro and in patient samples. The osteoblast-specific knockout of Tgfbr2 significantly induced bone metastasis. We showed that the enzalutamide-induced TGFBR2 decrease in osteoblasts was mediated by increased PTH1R (parathyroid hormone/parathyroid hormone-related peptide receptor), which resulted in TGFBR2 degradation, and that blocking PTH1R rescued the TGFBR2 decrease. Furthermore, we found that PTH1R up-regulation by enzalutamide was correlated with increased Pth1r promoter occupancy by transcription factor NR2F1. Our findings highlight a potential enzalutamide-resistance mechanism through TGFBR2 decrease in osteoblasts, thus suggesting future PTH1R-blocking approaches to overcome enzalutamide resistance in PCa bone metastasis.

cancer biology↗

bioRxiv2019

Prevalence of beta-lactam drug-resistance genes in commensal Escherichia coli contaminating ready-to-eat lettuce

The objective of this study was to evaluate the prevalence of antibiotic resistance and beta-lactam drug resistance genes in Escherichia coli isolated from ready-to-eat lettuce, obtained from local supermarkets in Northern California. Bags of lettuce were purchased from 4 chain supermarkets during three different periods--Oct 2018-Jan 2019, Feb 2019-Apr 2019 and May 2019-July 2019. From 91 packages of lettuce, we recovered 34 E. coli isolates from 22 (24%) lettuce samples. All E. coli isolates were genotyped by multilocus sequence typing (MLST), and we found 15 distinct sequence types (STs). Five of these genotypes (ST2819, ST4600, ST2432, ST1198 and ST5143) have been reported to cause infection in humans. Twenty (59%) E. coli isolates were found resistant to at least one of the antibacterial drugs. They included resistance to ampicillin (AMP, 85%) and ampicillin/sulbactam (SAM, 50%), cefoxitin (FOX, 40%) and cefuroxime (CXM, 35%). We found 8 (40%) of 20 beta-lactam resistant E. coli isolates to carry blaCTX-M; 5 (25%) tested positive for blaSHV, while only 4 (20%) tested positive for blaTEM. Additionally, we identified a class A broad-spectrum beta-lactamase SED-1 gene, blaSED, reported by others in Citrobacter sedlakii isolated from bile of a patient. This study found that a large proportion of fresh lettuce carry beta-lactam drug-resistant E. coli, which could serve as a reservoir for drug resistance genes that could potentially enter pathogens to cause human infections.

microbiology↗

bioRxiv2019

Nanog safeguards early embryogenesis against global activation of maternal β-catenin activity by interfering with TCF factors

Maternal {beta}-catenin activity is essential and critical for dorsal induction and its dorsal activation has been thoroughly studied. However, how the maternal {beta}-catenin activity is suppressed in the non-dorsal cells remains poorly understood. Nanog is known to play a central role for maintenance of the pluripotency and maternal-to-zygotic transition. Here we reveal a novel role of Nanog as a strong repressor of maternal Wnt/{beta}-catenin signaling to safeguard the embryo against hyper-activation of maternal {beta}-catenin activity and hyper-dorsalization. Knockdown of nanog at different levels led to either posteriorization or dorsalization, mimicking zygotic or maternal activation of Wnt/{beta}-catenin activities, and the maternal-zygotic mutant of nanog (MZnanog) showed strong activation of maternal {beta}-catenin and hyper-dorsalization. Although a constitutive-activator-type Nanog (Vp16-Nanog, lacking the N-terminal) perfectly rescued the defects of maternal to zygotic transition in MZnanog, it did not rescue the phenotypes resulting from {beta}-catenin activation. Mechanistically, the N-terminal of Nanog directly interacts with TCF and interferes with the binding of {beta}-catenin to TCF, thereby attenuating the transcriptional activity of {beta}-catenin. Therefore, our study establishes a novel role for Nanog in repressing maternal {beta}-catenin activity and demonstrates a transcriptional switch between {beta}-catenin/TCF and Nanog/TCF complexes, which safeguards the embryo from global activation of maternal {beta}-catenin activity.

developmental biology↗

bioRxiv2019

Chlamydomonas sp. UWO241 exhibits high cyclic electron flow and rewired metabolism under high salinity

The Antarctic green alga Chlamydomonas sp. UWO241 (UWO241) was isolated from the deep photic zone of a permanently Antarctic ice-covered lake. Adaptation to permanent low temperatures, hypersalinity, and extreme shade has resulted in survival strategies in this halotolerant psychrophile. One of the most striking phenotypes of UWO241 is an altered photosystem I (PSI) organization and constitutive PSI cyclic electron flow (CEF). To date, little attention has been paid to CEF during long-term stress acclimation and the consequences of sustained CEF in UWO241 are not known. In this study, we combined photobiology, proteomics, and metabolomics to understand the underlying role of sustained CEF in high salinity stress acclimation. High salt-grown UWO241 exhibited increased thylakoid proton motive flux and an increased capacity for NPQ. A Bestrophin-like Cl- channel was identified in the whole cell proteomes and transcriptome of UWO241 which likely supports ion homeostasis during high transthylakoid pH. Under high salt, a significant proportion of the upregulated enzymes were associated with the Calvin Benson Bassham Cycle (CBB), secondary metabolite biosynthesis, and protein translation. Two key enzymes of the Shikimate pathway, DAHP synthase and chorismate synthase, were also upregulated, as well as indole-3-glycerol phosphate synthase, an enzyme involved in biosynthesis of L-tryptophan and indole acetic acid. In addition, several compatible solutes (glycerol, proline and sucrose) accumulated to high levels in high salt-grown UWO241 cultures. We suggest that UWO241 maintains constitutively high CEF with associated PSI-cytb6f supercomplex to support robust growth and strong photosynthetic capacity under a constant growth regime of low temperatures and high salinity.

plant biology↗

bioRxiv2019

Riboflavin Directly Mediates the Dealkylation by Microbial Cytochrome P450 Monooxygeneses

As a vast repertoire of enzymes in nature, microbial cytochrome P450 monooxygenases require an activated form of flavin as a cofactor for the catalytic activity. Riboflavin is the precursor of FAD and FMN that serve as indispensable cofactors for flavoenzymes. In contrast to previous notion, here we describe the identification of an electron transfer process directly mediated by riboflavin for the N-dealkylation by microbial P450 monooxygenases. The electron relay from NADPH to riboflavin and then via activated oxygen to heme was proposed based on the combination of X-ray crystallography, molecular modeling and molecular dynamics simulation, site-directed mutagenesis and biochemical analysis of representative microbial P450 monooxygenases. This study provides new insights into the electron transfer mechanism in microbial P450 enzyme catalysis and likely in plants and mammals.

biochemistry↗

bioRxiv2019

The Manganese Salt (MnJ) Functions as A Potent Universal Adjuvant

Aluminum adjuvants have been used for a century in various vaccines due to its ability to potentiate humoral immunity and safety records since 1920s. Manganese is an essential micronutrient required for diverse biological activities in cells. We previously found that Mn2+ is a strong type I-interferon stimulator activating the cGAS-STING pathway. Herein we report that a colloidal manganese salt (MnJ) is a potent adjuvant to induce both humoral and cellular immune responses, particularly CTL activation. When administrated intranasally, MnJ was also a strong mucosal adjuvant, inducing high levels of IgA antibodies. MnJ strongly promoted dendritic cell maturation and antigen-specific T cell activation. Interestingly, IL-1/-18 induction and release by Mn2+-activated ASC-mediated inflammasomes were not observed. MnJ showed great adjuvant effects to all tested antigens including inactivated viruses, recombinant proteins and peptides by either intramuscular or intranasal immunization. These findings may have implications in developing potent but safe Mn2+-containing vaccines.

immunology↗

bioRxiv2019

MACF1 Facilitates SMAD7 Nuclear Translocation to Drive Bone Formation in Mice

MACF1 is a large crosslinker that contributes to cytoskeleton integrity and cell differentiation. Loss of MACF1 impairs multiple cellular functions in neuron development and epidermal migration, and is the molecular basis for many diseases such as heart failure and Parkinsons disease. MACF1 is highly abundant in bones, however, its involvements in osteogenic differentiation and bone formation are still unknown. In this study, by conditional gene targeting to delete the Macf1 gene specifically in MSCs, we observed ossification retardation and bone loss in MACF1 deficient mice in different developmental stages, which we traced to disorganized cytoskeleton and decreased osteogenic differentiation capability in MSCs. Further, we show that MACF1 interacts and facilitates SMAD7 nuclear translocation to initiate downstream transcription. These findings are hopefully to expand the biological scope of MACF1 in bones, and provide experimental basis for targeting MACF1 in degenerative bone diseases such as osteoporosis.

developmental biology↗

bioRxiv2019

Directed robust generation of functional retinal ganglion cells from Muller glia

Glaucoma and optic neuropathies cause progressive and irreversible degeneration of retinal ganglion cells (RGCs) and the optic nerve and are currently without any effective treatment. Previous research into cell replacement therapy of these neurodegenerative diseases has been stalled due to the limited capability for grafted RGCs to integrate into the retina and project properly along the long visual pathway to reach their brain targets. In vivo RGC regeneration would be a promising alternative approach but mammalian retinas lack regenerative capacity even though cold-blood vertebrates such as zebrafish have the full capacity to regenerate a damaged retina using Muller glia (MG) as retinal stem cells. Nevertheless, mammalian MG undergo limited neurogenesis when stimulated by retinal injury. Therefore, a fundamental question that remains to be answered is whether MG can be induced to efficiently regenerate functional RGCs for vision restoration in mammals. Here we show that without stimulating proliferation, the transcription factor (TF) Math5 together with a Brn3 TF family member are able to reprogram mature mouse MG into RGCs with exceedingly high efficiency while either alone has no or limited capacity. The reprogrammed RGCs extend long axons that make appropriate intra-retinal and extra-retinal projections through the entire visual pathway including the optic nerve, optic chiasm and optic tract to innervate both image-forming and non-image-forming brain targets. They exhibit typical neuronal electrophysiological properties and improve visual responses in two glaucoma mouse models: Brn3b null mutant mice and mice with the optic nerve crushed (ONC). Together, our data provide evidence that mammalian MG can be reprogrammed by defined TFs to achieve robust in vivo regeneration of functional RGCs as well as a promising new therapeutic approach to restore vision to patients with glaucoma and other optic neuropathies.

neuroscience↗

bioRxiv2019

Topology-Dependent Interference of Synthetic Gene Circuits by Growth Feedback

Growth-mediated feedback between synthetic gene circuits and host organisms leads to diverse emerged behaviors, including growth bistability and enhanced ultrasensitivity. However, the range of possible impacts of growth feedback on different gene circuits remains underexplored. Here, we mathematically and experimentally demonstrated that growth feedback affects the functions of memory gene circuits in a network topology-dependent way. Specifically, the memory of the self-activation circuit is quickly lost due to the fast growth-mediated dilution of the circuit products. Decoupling of growth feedback reveals its memory, manifested by its hysteresis property across a broad range of stimulus. On the contrary, the toggle switch is more refractory to the growth-mediated dilution and can retrieve its memory after the fast-growth phase. The underlying principle lies in the different dependence of active and repressive regulations in these circuits on the growth-mediated dilution. Our results unveil the topology-dependent mechanism on how growth-mediated feedback influences the behaviors of gene circuits.

synthetic biology↗